In this study, a morphodynamic numerical model is established with the Regional Ocean Modeling System(ROMS)to investigate the transient behavior of sand waves under realistic sea conditions. The simulation of sand wav...In this study, a morphodynamic numerical model is established with the Regional Ocean Modeling System(ROMS)to investigate the transient behavior of sand waves under realistic sea conditions. The simulation of sand wave evolution comprises two steps: 1) a regional-scale model is configured first to simulate the ocean hydrodynamics, i.e., tides and tidal currents, and 2) the transient behavior of sand waves is simulated in a small computational domain under the time-variant currents extracted from the large model. The evolution of sand waves on the continental shelf in the Beibu Gulf is specifically investigated. The numerical results of the two-year evolution of sand waves under normal sea conditions compare well with the field survey data. The transient behavior of sand waves in individual months shows that the sand waves are more stable in April and October than that in other months, which can be selected as the windows for seabed operations. The effects of sediment properties, including settling velocity, critical shear stress and surface erosion rate, on sand wave evolution are also analyzed. Then, the typhoon-induced currents are further superimposed on the tidal currents as the extreme weather conditions. Sand waves with the average wavelength generally have more active behavior than smaller or larger sand waves. The characteristics of the evolution of sand waves in an individual typhoon process are quite different for different hydrodynamic combinations. For the storm conditions, i.e., the real combination and maximum combination cases, the sand waves experience a significant migration together with a damping in height due to the dominant suspended sediment transport. For the mild conditions, i.e., the pure tidal current and minimum combination cases, the sand waves migrate less, but the heights continue growing due to the dominant bedload transport.展开更多
Offshore wind farm construction is nowadays state of the art in the wind power generation technology.However,deep water areas with huge amount of wind energy require innovative floating platforms to arrange and instal...Offshore wind farm construction is nowadays state of the art in the wind power generation technology.However,deep water areas with huge amount of wind energy require innovative floating platforms to arrange and install wind turbines in order to harness wind energy and generate electricity.The conventional floating offshore wind turbine system is typically in the state of force imbalance due to the unique sway characteristics caused by the unfixed foundation and the high center of gravity of the platform.Therefore,a floating wind farm for 3×3 barge array platforms with shared mooring system is presented here to increase stability for floating platform.The NREL 5 MW wind turbine and ITI Energy barge reference model is taken as a basis for this work.Furthermore,the unsteady aerodynamic load solution model of the floating wind turbine is established considering the tip loss,hub loss and dynamic stall correction based on the blade element momentum(BEM)theory.The second development of AQWA is realized by FORTRAN programming language,and aerodynamic-hydrodynamic-Mooring coupled dynamics model is established to realize the algorithm solution of the model.Finally,the 6 degrees of freedom(DOF)dynamic response of single barge platform and barge array under extreme sea condition considering the coupling effect of wind and wave were observed and investigated in detail.The research results validate the feasibility of establishing barge array floating wind farm,and provide theoretical basis for further research on new floating wind farm.展开更多
As the key equipment of floating liquefied natural gas(FLNG)process,the performance of spiral wound heat exchanger(SWHE)influences operation costs and reliability of the whole system.The sea conditions destroy the fal...As the key equipment of floating liquefied natural gas(FLNG)process,the performance of spiral wound heat exchanger(SWHE)influences operation costs and reliability of the whole system.The sea conditions destroy the falling film flow state of the refrigeration and then affect the heat transfer performance of FLNG SWHE.In order to design and optimize the SWHE,a cryogenic experimental device of FLNG process and a numerical model of falling film flow have been constructed to study the effects of sea conditions on the falling film flow and heat transfer characteristics of SWHE.The cryogenic experimental results show that the pitching conditions have larger effects on the heat transfer performance than yawing.Under the pitching angle of 7°,the natural gas temperature and gaseous refrigerant temperature increase by 3.22°C and 7.42°C,respectively.The flow rates of refrigerant and feed natural gas have a great impact on the heat transfer performance of SWHE under pitching and compound sloshing conditions.When the tilt angle increases to 9°,the tube structure with outer diameter D=8 mm and pipe spacing S=4 mm is recommended to reduce the drying area of the pipe wall surface.展开更多
In this study, the statistical characterization of sea conditions in the East China Sea(ECS) is investigated by analyzing a significant wave height and wind speed data at a 6-hour interval for 30 years(1980–2009), wh...In this study, the statistical characterization of sea conditions in the East China Sea(ECS) is investigated by analyzing a significant wave height and wind speed data at a 6-hour interval for 30 years(1980–2009), which was simulated and computed using the WAVEWATCH Ⅲ(WW3) model. The monthly variations of these parameters showed that the significant wave height and wind speed have minimum values of 0.73 m and 5.15 ms^(-1) and 1.73 m and 8.24 ms^(-1) in the month of May and December, respectively. The annual, seasonal, and monthly mean sea state characterizations showed that the slight sea generally prevailed in the ECS and had nearly the highest occurrence in all seasons and months. Additionally, the moderate sea prevailed in the winter months of December and January, while the smooth(wavelets) sea prevailed in May. Furthermore, the spatial variation of sea states showed that the calm and smooth sea had the largest occurrences in the northern ECS. The slight sea occurred mostly(above 30%) in parts of the ECS and the surrounding locations, while higher occurrences of the rough and very rough seas were distributed in waters between the southwest ECS and the northeast South China Sea(SCS). The occurrences of the phenomenal sea conditions are insignificant and are distributed in the northwest Pacific and its upper region, which includes the Southern Kyushu-Palau Ridge and Ryukyu Trench.展开更多
Autonomous underwater vehicles (AUVs) navigating in complex sea conditions usually require a strong control system to keep the fastness and stability. The nonlinear trajectory tracking control system of a new AUV in c...Autonomous underwater vehicles (AUVs) navigating in complex sea conditions usually require a strong control system to keep the fastness and stability. The nonlinear trajectory tracking control system of a new AUV in complex sea conditions was presented. According to the theory of submarines,the six-DOF kinematic and dynamic models were decomposed into two mutually non-coupled vertical and horizontal plane subsystems. Then,different sliding mode control algorithms were used to study the trajectory tracking control. Because the yaw angle and yaw angle rate rather than the displacement of the new AUV can be measured directly on the horizontal plane,the sliding mode control algorithm combining cross track error method and line of sight method was used to fulfill its high-precision trajectory tracking control in the complex sea conditions. As the vertical displacement of the new AUV can be measured,in order to achieve the tracking of time-varying depth signal,a stable sliding mode controller was designed based on the single-input multi-state system,which took into account the characteristic of the hydroplane and the amplitude and rate constraints of the hydroplane angle. Moreover,the application of dynamic boundary layer can improve the robustness and control accuracy of the system. The computational results show that the designed sliding mode control systems of the horizontal and vertical planes can ensure the trajectory tracking performance and accuracy of the new AUV in complex sea conditions. The impacts of currents and waves on the sliding mode controller of the new AUV were analyzed qualitatively and quantitatively by comparing the trajectory tracking performance of the new AUV in different sea conditions,which provides an effective theoretical guidance and technical support for the control system design of the new AUV in real complex environment.展开更多
The mobility of the vectored thruster AUV in different environment is the important premise of control system design. The new type of autonomous underwater vehicle (AUV) equipped with rudders and vectored thrusters wh...The mobility of the vectored thruster AUV in different environment is the important premise of control system design. The new type of autonomous underwater vehicle (AUV) equipped with rudders and vectored thrusters which are combined to control the course is studied. Firstly, Euler angles representation and quaternion method are applied to establish six-DOF kinematic model respectively, then Newton second law and Lagrangian approach are used to deduce the vectored thruster AUV's nonlinear dynamic equations with six degrees of freedom (DOF) respectively in complex sea conditions based on the random wave theory according to the structural and kinetic characteristics of the vectored thruster AUV in this paper. The kinematic models and dynamic models based on different theories have the same expression and conclusion, which shows that the kinematic models and dynamic models of the vectored thruster AUV are accurate. The Runge-Kutta arithmetic is used to solve the dynamic equations, which not only can simulate the motions such as cruise and hover but also can describe the vehicle's low-frequency and high-frequency motion. The results of computation show that the mobility of the vectored thruster AUV in interference-free environment and the integrated signals including low-frequency motion signal and high-frequency motion signal in environmental disturbance accord with practical situation, which not only solve the problem of especial singularities when the pitch angle θ = ±90° but also clears up the difficulties of computation and display of the coupled nonlinear motion equations in complex sea conditions. Moreover, the high maneuverability of the vectored thruster AUV equipped with rudders and vectored thrusters is validated, which lays a foundation for the control system design.展开更多
Sea ice conditions in Liaodong Bay of China are often described by sea ice grades,which classify annual sea ice conditions based on the annual maximum sea ice thickness(AM-SIT)and annual maximum floating ice extent(AM...Sea ice conditions in Liaodong Bay of China are often described by sea ice grades,which classify annual sea ice conditions based on the annual maximum sea ice thickness(AM-SIT)and annual maximum floating ice extent(AM-FIE).The joint probability distribution of AM-SIT and AM-FIE was established on the basis of their data pairs from 1949/1950 to 2019/2020 in Liaodong Bay.The joint intensity index of the sea ice condition in the current year is calculated,and the joint classification criteria of the sea ice grades in past years are established on the basis of the joint intensity index series.A comparison of the joint criteria with the 1973 and 2022 criteria revealed that the joint criteria of the sea ice grade match well,and the joint intensity index can be used to quantify the sea ice condition over the years.A time series analysis of the sea ice grades and the joint intensity index sequences based on the joint criteria are then performed.Results show a decreasing trend of the sea ice condition from 1949/1950 to 2019/2020,a mutation in 1990/1991,and a period of approximately 91 years of the sea ice condition.In addition,the Gray-Markov model(GMM)is applied to predict the joint sea ice grade and the joint intensity index of the sea ice condition series in future years,and the error between the results and the actual sea ice condition in 2020/2021 is small.展开更多
Conditioning regimens employed in autologous stem cell transplantation have been proven useful in various hematological disorders and underlying malignancies;however,despite being efficacious in various instances,nega...Conditioning regimens employed in autologous stem cell transplantation have been proven useful in various hematological disorders and underlying malignancies;however,despite being efficacious in various instances,negative consequences have also been recorded.Multiple conditioning regimens were extracted from various literature searches from databases like PubMed,Google scholar,EMBASE,and Cochrane.Conditioning regimens for each disease were compared by using various end points such as overall survival(OS),progression free survival(PFS),and leukemia free survival(LFS).Variables were presented on graphs and analyzed to conclude a more efficacious conditioning regimen.In multiple myeloma,the most effective regimen was high dose melphalan(MEL)given at a dose of 200/mg/m2.The comparative results of acute myeloid leukemia were presented and the regimens that proved to be at an admirable position were busulfan(BU)+MEL regarding OS and BU+VP16 regarding LFS.In case of acute lymphoblastic leukemia(ALL),BU,fludarabine,and etoposide(BuFluVP)conferred good disease control not only with a paramount improvement in survival rate but also low risk of recurrence.However,for ALL,chimeric antigen receptor(CAR)T cell therapy was preferred in the context of better OS and LFS.With respect to Hodgkin’s lymphoma,mitoxantrone(MITO)/MEL overtook carmustine,VP16,cytarabine,and MEL in view of PFS and vice versa regarding OS.Non-Hodgkin’s lymphoma patients were administered MITO(60 mg/m2)and MEL(180 mg/m2)which showed promising results.Lastly,amyloidosis was considered,and the regimen that proved to be competent was MEL 200(200 mg/m2).This review article demonstrates a comparison between various conditioning regimens employed in different diseases.展开更多
The noise that comes from finite element simulation often causes the model to fall into the local optimal solution and over fitting during optimization of generator.Thus,this paper proposes a Gaussian Process Regressi...The noise that comes from finite element simulation often causes the model to fall into the local optimal solution and over fitting during optimization of generator.Thus,this paper proposes a Gaussian Process Regression(GPR)model based on Conditional Likelihood Lower Bound Search(CLLBS)to optimize the design of the generator,which can filter the noise in the data and search for global optimization by combining the Conditional Likelihood Lower Bound Search method.Taking the efficiency optimization of 15 kW Permanent Magnet Synchronous Motor as an example.Firstly,this method uses the elementary effect analysis to choose the sensitive variables,combining the evolutionary algorithm to design the super Latin cube sampling plan;Then the generator-converter system is simulated by establishing a co-simulation platform to obtain data.A Gaussian process regression model combing the method of the conditional likelihood lower bound search is established,which combined the chi-square test to optimize the accuracy of the model globally.Secondly,after the model reaches the accuracy,the Pareto frontier is obtained through the NSGA-II algorithm by considering the maximum output torque as a constraint.Last,the constrained optimization is transformed into an unconstrained optimizing problem by introducing maximum constrained improvement expectation(CEI)optimization method based on the re-interpolation model,which cross-validated the optimization results of the Gaussian process regression model.The above method increase the efficiency of generator by 0.76%and 0.5%respectively;And this method can be used for rapid modeling and multi-objective optimization of generator systems.展开更多
Objective:To analyze the effects of providing extended rehabilitation nursing services at home to patients with coronary heart disease(CHD)combined with heart failure(CHF)on psychological improvement and adherence to ...Objective:To analyze the effects of providing extended rehabilitation nursing services at home to patients with coronary heart disease(CHD)combined with heart failure(CHF)on psychological improvement and adherence to medical compliance behavior.Methods:79 patients with CHD with CHF admitted to Sijia Town Central Health Hospital,Haimen District,Nantong City,Jiangsu Province,between June 2021 and June 2023 were selected and grouped according to the randomized numerical table method.The control group(39 cases)was provided with conventional nursing care and extended rehabilitation nursing care at home was provided to the observation group(40 cases).The psychological status,adherence to medical behaviors,cardiac function,and complications between both groups were compared.Results:The scores of anxieties and depression self-assessment scales(SAS,SDS)of patients in the observation group were lower than those of the control group(t=2.954,3.212;P<0.05);the compliance of patients in the observation group was higher than that of the control group(P<0.05).The levels of left ventricular ejection fraction,end-systolic and end-diastolic internal diameters(LVEF,LVESD,LVEDD)of patients in the observation group at 58.02±5.34%,44.49±5.16 mm,and 49.16±5.76 mm respectively were better than those of the control group after nursing care(t=3.205,3.288,2.633;P<0.05);the complication rate of the observation group was lower than that of the control group(P<0.05).Conclusion:Extended rehabilitation nursing at home exhibited a psychological regulation effect on CHD with CHF patients,improved their medical compliance,improved cardiac function,reduced the incidence of complications,and had significant application value.展开更多
Aptian is characterized by widespread deposition of organic-rich sediment.The Aptian bitumen limestone horizon,which is thin decimetre-thick sequences,locally crops out in the Kircaova area,Eastern Black Sea Region(Ea...Aptian is characterized by widespread deposition of organic-rich sediment.The Aptian bitumen limestone horizon,which is thin decimetre-thick sequences,locally crops out in the Kircaova area,Eastern Black Sea Region(Eastern Pontides).They are well correlated with Aptian bitumen limestone in the other Tethys Reams.They are proposed as episodes of increased organic matter.However,background factors controlling organic matter enrichment are poorly known.In this study,we present new inorganic geochemistry,including trace elements,rare earth elements(REE),redox-sensitive elements(RSE),stable-isotopes(δ~(18)O andδ~(13)C),and total organic carbon(TOC).We integrated new geochemical data with existing stratigraphy,paleontology,and organic chemistry data to provide new insight into the depositional environment and paleoclimate conditions during Aptian.The lacustrine bitumen limestone(LBL)samples have variedδ~(13)C(ave.-1.45‰)andδ~(18)O(ave.-4.50‰).They possess distinct REE patterns,with an average of REE(ave.14.45 ppm)and Y/Ho(ave.35)ratios.In addition,they have variable Nd/YbN(0.28-0.81;ave.0.56)and Ce/Ce*(0.68-0.97;ave.0.86),and relatively high Eu^(*)/Eu(1.23-1.53;ave.1.35).They display seawater signatures with reduced oxygen conditions.The enrichment in RSE(Mo,Cu,Ni,and Zn)and the low Mo/TOC(0.70-3.69;ave.2.41)support a certain degree of water restriction.The high Sr/Ba,Sr/Cu,Ga/Rb,and K/Al records of the LBL facies suggest hot house climatic conditions.The sedimentary environment was probably an isolated basin that is transformed from the marine basin.In addition to depositional conditions,the regional parameters such as the climate,increased run-off period,nutrient levels,alkalinity level,and dominant carbonate producers favored the enrichment in organic matter of LBL facies.Thus,extreme greenhouse palaeoclimate conditions have an important role in organic matter enrichment in the isolated basin.Our results are conformable with the published data from marine,semi-restricted basin,and lacustrine settings in the different parts of the Tethys margin.Thus,this approach provides the first insight into the Aptian greenhouse paleo-climate conditions of the Eastern Black Sea Region,NE Turkey.展开更多
Reliable wave information is critical for marine engineering.Numerical wave models are useful tools to obtain wave information with continuous spatiotemporal distributions.However,the accuracy of model results highly ...Reliable wave information is critical for marine engineering.Numerical wave models are useful tools to obtain wave information with continuous spatiotemporal distributions.However,the accuracy of model results highly depends on the quality of wind forcing.In this study,we utilize observations from five buoys deployed in the northern South China Sea from August to September 2017.Notably,these buoys successfully recorded wind field and wave information during the passage of five tropical cyclones of different intensities without sustaining any damage.Based on these unique observations,we evaluated the quality of four widely used wind products,namely CFSv2,ERA5,CCMP,and ERAI.Our analysis showed that in the northern South China Sea,ERA5 performed best compared to buoy observations,especially in terms of maximum wind speed values at 10 m height(U10),extreme U10 occurrence time,and overall statistical indicators.CFSv2 tended to overestimate non-extreme U10 values.CCMP showed favorable statistical performance at only three of the five buoys,but underestimated extreme U10 values at all buoys.ERAI had the worst performance under both normal and tropical cyclone conditions.In terms of wave hindcast accuracy,ERA5 outperformed the other reanalysis products,with CFSv2 and CCMP following closely.ERAI showed poor performance especially in the upper significant wave heights.Furthermore,we found that the wave hindcasts did not improve with increasing spatiotemporal resolution,with spatial resolution up to 0.5°.These findings would help in improving wave hindcasts under extreme conditions.展开更多
As a type of reciprocating machine, the reciprocating compressor has a compact structure and many excitation sources.Once the small end bearing of the connecting rod is worn, it is easy to cause the sintering of the b...As a type of reciprocating machine, the reciprocating compressor has a compact structure and many excitation sources.Once the small end bearing of the connecting rod is worn, it is easy to cause the sintering of the bearing and the abnormal vibration of the body.Based on the characteristics of poor lubrication state and complex force of connecting rod small head bearing, a mixed lubrication model considering oil groove feed was established, and the dynamic simulation of the reciprocating compressor model with lubricated bearings was carried out;considering different speeds and gas load conditions, the law of the impact of the eigenvalues changing with working conditions was explored.The fault simulation experiment was carried out by selecting representative working conditions, which verified the correctness of the simulation method.The study found that two contact collisions between the pin and the bearing bush occurred in one cycle, the collision impact was more severe under the wear fault, and the existence of the gap made the dynamic response more sensitive to the change of working conditions.This research provides ideas for the location and feature extraction of fault symptom signal angular segments in the process of complex measured signal processing.展开更多
The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size...The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size structure in summer 2017 in the YS and ECS were assessed using ZooScan imaging analysis.Zooplankton abundance and biovolume ranged 2.94–1187.14 inds./m^(3)and 3.13–3438.51 mm^(3)/m^(3),respectively.Based on the biovolume data of the categorized size classes of 26 identified taxonomic groups,the zooplankton community was classified into five groups,and each group was coupled with distinctive oceanographic features.Under the influence of the Yellow Sea Cold Water Mass,the Yellow Sea offshore group featured the lowest bottom temperature(10.84±3.42℃)and the most abundant Calanoids(mainly in the 2–3 mm size class).In the Yellow Sea inshore group,Hydrozoans showed the largest biovolume and dominated in the 3–4-mm and>5-mm size classes.The East China Sea offshore group,which was affected by the Kuroshio Branch Current,featured high temperature and salinity,and the lowest bottom dissolved oxygen(2.58±0.5 mg/L).The lowest values of zooplankton abundance and biovolume in the East China Sea offshore group might be attributed to the bottom dissolved oxygen contents.The East China Sea inshore group,which was mainly influenced by the Zhejiang-Fujian Coastal Current and Changjiang Diluted Water,was characterized by high chlorophyll a and the largest biovolume of carnivorous Siphonophores(280.82±303.37 mm^(3)/m^(3)).The Changjiang River estuary offshore group showed the most abundant Cyclopoids,which might be associated with the less turbid water mass in this region.Seawater temperature was considered the most important factor in shaping the size compositions of Calanoids in different groups.展开更多
This study was conducted to provide a preliminary assessment of the sea cucumber fishery in Aurora, Philippines. This was conducted from February to June 2013. All sea cucumber gatherers and traders, obtained through ...This study was conducted to provide a preliminary assessment of the sea cucumber fishery in Aurora, Philippines. This was conducted from February to June 2013. All sea cucumber gatherers and traders, obtained through snowball sampling, in each identified sea cucumber fishery area in six coastal municipalities (Baler, Dipaculao, Dinalungan, Casiguran, Dilasag and Dingalan) were interviewed using a structured interview schedule and focused group discussions (FGD). Results revealed that gathering sea cucumbers were accomplished by handpicking, skin diving or compressor diving. A total of 15 commercial species were regularly gathered. Out of this, three species are of very high economic value (≥Php 4000/kg) (Holothuria nobilis, Holothuria scabra, and Actinopyga lecanora). The average number of kilograms harvested per hour per trip ranges from 0.21 (Holothuria fuscopunctata) to 2.71 (Holothuria scabra), while the average size of commonly gathered sea cucumber varies among species with Holothuria lecanora showed an average length (29.26 cm) greater than recorded 24 cm. Processing mainly involves washing, slicing, boiling, drying and packing. Processed sea cucumbers or trepan were sold to middlemen or direct buyers who usually offered higher prices (36.36% up to 69.20%) than the former. Problems encountered by sea cucumber gatherers and traders include a decline in total catch, a shift in area of collection from intertidal zones to deeper waters, an increase in the number of hours spent in finding and gathering sea cucumbers, the use of compressors in gathering, the decline of larger species and gathering of smaller sizes in huge amount, the absence of conservation program for sea cucumber, and the lenient implementation of government policies with regards to coastal resources management.展开更多
The aquaculture industry has developed significantly over the past few decades and has had a substantial impact on the global food supply and marine fisheries resources.However,some problems arise behind the scenes du...The aquaculture industry has developed significantly over the past few decades and has had a substantial impact on the global food supply and marine fisheries resources.However,some problems arise behind the scenes due to excessive intensive farming,such as slow animal growth,frequent disease,and lipid metabolism disorders.These problems have limited the sustainable development of the aquaculture industry,and a continuable solution is required.The use of fungal polysaccharide appears to provide a solution to these problems.Therefore,different supplemented levels of Poria cocos polysaccharide(PCP)(0,0.4,0.8,1.2,1.6,and 2.0 g/kg,respectively)were fed to spotted sea bass(Lateolabrax maculatus)in similar size(30.28±0.18 g)in current study.The effects of PCP on growth,physiological parameters,and lipid metabolism of spotted sea bass were investigated after a 4-week rearing period.Results showed,fish with PCP intake presented a significantly higher weight gain,specific growth rate,and a significantly lower feed conversion ratio.Significantly higher trypsin activity in liver and intestine were observed in fish with PCP intake.The superoxide dismutase activity in serum and liver of fish with PCP intake were significantly improved,while significantly higher serum total antioxidant capacity and hepatic catalase activity were also observed.However,no significant differences in lysozyme and alkaline phosphatase activity were evident among groups.Fish with PCP intake showed a significantly lower total cholesterol,but no noteworthy change in triglyceride and lipid-metabolismrelated genes expression were observed among groups.Results indicated that intake of PCP has a positive effect on growth and antioxidant capacity of spotted sea bass,but seems to have a limited effect on the non-specific immunity and lipid metabolism of spotted sea bass.Based on the regression analysis results,1.4 g/kg of PCP is the optimal dose for spotted sea bass in size(30.28±0.18 g).展开更多
The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to s...The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately 0.93.The water temperature measured from the Advanced Research and Global Observation Satellite was applied to validate the model simulation.Accordingly,the RMSE of the SST is 0.92℃ with a COR of approximately 0.99.As revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively high.The variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak SWH.Moreover,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio Current.The sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the ocean.The variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in May.Moreover,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current.展开更多
The abundance, distribution and diversity of epibenthic echinoderm were investigated at Dungonab Bay in the Red Sea coastal water of the Sudan. Four permanent line transects were chosen. Eight (30 × 2) square met...The abundance, distribution and diversity of epibenthic echinoderm were investigated at Dungonab Bay in the Red Sea coastal water of the Sudan. Four permanent line transects were chosen. Eight (30 × 2) square metre belt transects along each permanent line transect at 20 metre intervals were used to collect data. The data were subjected to univariate and multivariate analyses. Spatial variations of epibenthic echinoderm abundance were assessed with one-way analysis of variance. Hierarchical agglomerative clustering was used to identify and illustrate the similarities in echinoderm abundance between line transects and between belt transects. Indices of richness (d), diversity (H'), evenness (J') and dominance (C) were used to explain the diversity of epibenthic echinoderm species. The distribution pattern of each echinoderm species was determined in each permanent line transect. A total of 986 individuals were recorded within sixteen species of epibenthic echinoderms in the four line transects. Holothuriidae was the dominant family (5 species and 342 individuals). The most abundant echinoderms species was Pearsonothuria graeffei (77 individuals, about 7.81%). Abundances intra-transects and intra-families were insignificant (f = 1.67, p = 0.183, df = 3 and f = 3.24, p = 0.083, df = 9, respectively). The highest values of Shannon-Wiener diversity index (H'), Pielou evenness index (J'), Margalef species richness index (d), and Simpson Dominance index (C) were 2.738, 0.9875, 2.791 and 0.07159, respectively. The distribution patterns of all species in the study transects varied between clumped and uniform, with the exception of Asthenosoma varium of the Echinothuridae family, which had clumped distribution patterns in all transects. The study concluded that Dungonab Bay supports rich and diverse communities of epibenthic echinoderms.展开更多
Chlorophyll-a(Chl-a)concentration is a primary indicator for marine environmental monitoring.The spatio-temporal variations of sea surface Chl-a concentration in the Yellow Sea(YS)and the East China Sea(ECS)in 2001-20...Chlorophyll-a(Chl-a)concentration is a primary indicator for marine environmental monitoring.The spatio-temporal variations of sea surface Chl-a concentration in the Yellow Sea(YS)and the East China Sea(ECS)in 2001-2020 were investigated by reconstructing the MODIS Level 3 products with the data interpolation empirical orthogonal function(DINEOF)method.The reconstructed results by interpolating the combined MODIS daily+8-day datasets were found better than those merely by interpolating daily or 8-day data.Chl-a concentration in the YS and the ECS reached its maximum in spring,with blooms occurring,decreased in summer and autumn,and increased in late autumn and early winter.By performing empirical orthogonal function(EOF)decomposition of the reconstructed data fields and correlation analysis with several potential environmental factors,we found that the sea surface temperature(SST)plays a significant role in the seasonal variation of Chl a,especially during spring and summer.The increase of SST in spring and the upper-layer nutrients mixed up during the last winter might favor the occurrence of spring blooms.The high sea surface temperature(SST)throughout the summer would strengthen the vertical stratification and prevent nutrients supply from deep water,resulting in low surface Chl-a concentrations.The sea surface Chl-a concentration in the YS was found decreased significantly from 2012 to 2020,which was possibly related to the Pacific Decadal Oscillation(PDO).展开更多
In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as an...In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51579232 and 51890913)the Open Funding of State Key Laboratory of Hydraulic Engineering Simulation and Safety (Grant No. HESS-1712)。
文摘In this study, a morphodynamic numerical model is established with the Regional Ocean Modeling System(ROMS)to investigate the transient behavior of sand waves under realistic sea conditions. The simulation of sand wave evolution comprises two steps: 1) a regional-scale model is configured first to simulate the ocean hydrodynamics, i.e., tides and tidal currents, and 2) the transient behavior of sand waves is simulated in a small computational domain under the time-variant currents extracted from the large model. The evolution of sand waves on the continental shelf in the Beibu Gulf is specifically investigated. The numerical results of the two-year evolution of sand waves under normal sea conditions compare well with the field survey data. The transient behavior of sand waves in individual months shows that the sand waves are more stable in April and October than that in other months, which can be selected as the windows for seabed operations. The effects of sediment properties, including settling velocity, critical shear stress and surface erosion rate, on sand wave evolution are also analyzed. Then, the typhoon-induced currents are further superimposed on the tidal currents as the extreme weather conditions. Sand waves with the average wavelength generally have more active behavior than smaller or larger sand waves. The characteristics of the evolution of sand waves in an individual typhoon process are quite different for different hydrodynamic combinations. For the storm conditions, i.e., the real combination and maximum combination cases, the sand waves experience a significant migration together with a damping in height due to the dominant suspended sediment transport. For the mild conditions, i.e., the pure tidal current and minimum combination cases, the sand waves migrate less, but the heights continue growing due to the dominant bedload transport.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.52006148 and 51976131)the Capacity Building Project of Local Institutions of Shanghai“Action Plan for Scientific and Technological”(Grant Nos.19060502200).
文摘Offshore wind farm construction is nowadays state of the art in the wind power generation technology.However,deep water areas with huge amount of wind energy require innovative floating platforms to arrange and install wind turbines in order to harness wind energy and generate electricity.The conventional floating offshore wind turbine system is typically in the state of force imbalance due to the unique sway characteristics caused by the unfixed foundation and the high center of gravity of the platform.Therefore,a floating wind farm for 3×3 barge array platforms with shared mooring system is presented here to increase stability for floating platform.The NREL 5 MW wind turbine and ITI Energy barge reference model is taken as a basis for this work.Furthermore,the unsteady aerodynamic load solution model of the floating wind turbine is established considering the tip loss,hub loss and dynamic stall correction based on the blade element momentum(BEM)theory.The second development of AQWA is realized by FORTRAN programming language,and aerodynamic-hydrodynamic-Mooring coupled dynamics model is established to realize the algorithm solution of the model.Finally,the 6 degrees of freedom(DOF)dynamic response of single barge platform and barge array under extreme sea condition considering the coupling effect of wind and wave were observed and investigated in detail.The research results validate the feasibility of establishing barge array floating wind farm,and provide theoretical basis for further research on new floating wind farm.
基金supported by the National Natural Science Foundation of China(U21B2085)the Natural Science Foundation of Shandong Province of China(ZR2021QE073)+2 种基金the China Postdoctoral Science Foundation(2021M703587)the Qingdao Postdoctoral Applied Research Project(qdyy20200096)Fundamental Research Funds for the Central Universities(20CX06076A)
文摘As the key equipment of floating liquefied natural gas(FLNG)process,the performance of spiral wound heat exchanger(SWHE)influences operation costs and reliability of the whole system.The sea conditions destroy the falling film flow state of the refrigeration and then affect the heat transfer performance of FLNG SWHE.In order to design and optimize the SWHE,a cryogenic experimental device of FLNG process and a numerical model of falling film flow have been constructed to study the effects of sea conditions on the falling film flow and heat transfer characteristics of SWHE.The cryogenic experimental results show that the pitching conditions have larger effects on the heat transfer performance than yawing.Under the pitching angle of 7°,the natural gas temperature and gaseous refrigerant temperature increase by 3.22°C and 7.42°C,respectively.The flow rates of refrigerant and feed natural gas have a great impact on the heat transfer performance of SWHE under pitching and compound sloshing conditions.When the tilt angle increases to 9°,the tube structure with outer diameter D=8 mm and pipe spacing S=4 mm is recommended to reduce the drying area of the pipe wall surface.
基金supported by the National Key Research and Development Program of China(No.2016YFC1401405)the National Natural Science Foundation of China(No.41376010)
文摘In this study, the statistical characterization of sea conditions in the East China Sea(ECS) is investigated by analyzing a significant wave height and wind speed data at a 6-hour interval for 30 years(1980–2009), which was simulated and computed using the WAVEWATCH Ⅲ(WW3) model. The monthly variations of these parameters showed that the significant wave height and wind speed have minimum values of 0.73 m and 5.15 ms^(-1) and 1.73 m and 8.24 ms^(-1) in the month of May and December, respectively. The annual, seasonal, and monthly mean sea state characterizations showed that the slight sea generally prevailed in the ECS and had nearly the highest occurrence in all seasons and months. Additionally, the moderate sea prevailed in the winter months of December and January, while the smooth(wavelets) sea prevailed in May. Furthermore, the spatial variation of sea states showed that the calm and smooth sea had the largest occurrences in the northern ECS. The slight sea occurred mostly(above 30%) in parts of the ECS and the surrounding locations, while higher occurrences of the rough and very rough seas were distributed in waters between the southwest ECS and the northeast South China Sea(SCS). The occurrences of the phenomenal sea conditions are insignificant and are distributed in the northwest Pacific and its upper region, which includes the Southern Kyushu-Palau Ridge and Ryukyu Trench.
基金Project(2006AA09Z235) supported by the National High Technology Research and Development Program of ChinaProject(CX2009B003) supported by Hunan Provincial Innovation Foundation For Postgraduates,China
文摘Autonomous underwater vehicles (AUVs) navigating in complex sea conditions usually require a strong control system to keep the fastness and stability. The nonlinear trajectory tracking control system of a new AUV in complex sea conditions was presented. According to the theory of submarines,the six-DOF kinematic and dynamic models were decomposed into two mutually non-coupled vertical and horizontal plane subsystems. Then,different sliding mode control algorithms were used to study the trajectory tracking control. Because the yaw angle and yaw angle rate rather than the displacement of the new AUV can be measured directly on the horizontal plane,the sliding mode control algorithm combining cross track error method and line of sight method was used to fulfill its high-precision trajectory tracking control in the complex sea conditions. As the vertical displacement of the new AUV can be measured,in order to achieve the tracking of time-varying depth signal,a stable sliding mode controller was designed based on the single-input multi-state system,which took into account the characteristic of the hydroplane and the amplitude and rate constraints of the hydroplane angle. Moreover,the application of dynamic boundary layer can improve the robustness and control accuracy of the system. The computational results show that the designed sliding mode control systems of the horizontal and vertical planes can ensure the trajectory tracking performance and accuracy of the new AUV in complex sea conditions. The impacts of currents and waves on the sliding mode controller of the new AUV were analyzed qualitatively and quantitatively by comparing the trajectory tracking performance of the new AUV in different sea conditions,which provides an effective theoretical guidance and technical support for the control system design of the new AUV in real complex environment.
基金supported by National Hi-tech Research and Development Program of China(863 Program, Grant No. 2006AA09Z235)Hunan Provincial Innovation Foundation For Postgraduate of China(Grant No. CX2009B003)
文摘The mobility of the vectored thruster AUV in different environment is the important premise of control system design. The new type of autonomous underwater vehicle (AUV) equipped with rudders and vectored thrusters which are combined to control the course is studied. Firstly, Euler angles representation and quaternion method are applied to establish six-DOF kinematic model respectively, then Newton second law and Lagrangian approach are used to deduce the vectored thruster AUV's nonlinear dynamic equations with six degrees of freedom (DOF) respectively in complex sea conditions based on the random wave theory according to the structural and kinetic characteristics of the vectored thruster AUV in this paper. The kinematic models and dynamic models based on different theories have the same expression and conclusion, which shows that the kinematic models and dynamic models of the vectored thruster AUV are accurate. The Runge-Kutta arithmetic is used to solve the dynamic equations, which not only can simulate the motions such as cruise and hover but also can describe the vehicle's low-frequency and high-frequency motion. The results of computation show that the mobility of the vectored thruster AUV in interference-free environment and the integrated signals including low-frequency motion signal and high-frequency motion signal in environmental disturbance accord with practical situation, which not only solve the problem of especial singularities when the pitch angle θ = ±90° but also clears up the difficulties of computation and display of the coupled nonlinear motion equations in complex sea conditions. Moreover, the high maneuverability of the vectored thruster AUV equipped with rudders and vectored thrusters is validated, which lays a foundation for the control system design.
基金supported by the National Natural Science Foundation of China(No.52171284).
文摘Sea ice conditions in Liaodong Bay of China are often described by sea ice grades,which classify annual sea ice conditions based on the annual maximum sea ice thickness(AM-SIT)and annual maximum floating ice extent(AM-FIE).The joint probability distribution of AM-SIT and AM-FIE was established on the basis of their data pairs from 1949/1950 to 2019/2020 in Liaodong Bay.The joint intensity index of the sea ice condition in the current year is calculated,and the joint classification criteria of the sea ice grades in past years are established on the basis of the joint intensity index series.A comparison of the joint criteria with the 1973 and 2022 criteria revealed that the joint criteria of the sea ice grade match well,and the joint intensity index can be used to quantify the sea ice condition over the years.A time series analysis of the sea ice grades and the joint intensity index sequences based on the joint criteria are then performed.Results show a decreasing trend of the sea ice condition from 1949/1950 to 2019/2020,a mutation in 1990/1991,and a period of approximately 91 years of the sea ice condition.In addition,the Gray-Markov model(GMM)is applied to predict the joint sea ice grade and the joint intensity index of the sea ice condition series in future years,and the error between the results and the actual sea ice condition in 2020/2021 is small.
文摘Conditioning regimens employed in autologous stem cell transplantation have been proven useful in various hematological disorders and underlying malignancies;however,despite being efficacious in various instances,negative consequences have also been recorded.Multiple conditioning regimens were extracted from various literature searches from databases like PubMed,Google scholar,EMBASE,and Cochrane.Conditioning regimens for each disease were compared by using various end points such as overall survival(OS),progression free survival(PFS),and leukemia free survival(LFS).Variables were presented on graphs and analyzed to conclude a more efficacious conditioning regimen.In multiple myeloma,the most effective regimen was high dose melphalan(MEL)given at a dose of 200/mg/m2.The comparative results of acute myeloid leukemia were presented and the regimens that proved to be at an admirable position were busulfan(BU)+MEL regarding OS and BU+VP16 regarding LFS.In case of acute lymphoblastic leukemia(ALL),BU,fludarabine,and etoposide(BuFluVP)conferred good disease control not only with a paramount improvement in survival rate but also low risk of recurrence.However,for ALL,chimeric antigen receptor(CAR)T cell therapy was preferred in the context of better OS and LFS.With respect to Hodgkin’s lymphoma,mitoxantrone(MITO)/MEL overtook carmustine,VP16,cytarabine,and MEL in view of PFS and vice versa regarding OS.Non-Hodgkin’s lymphoma patients were administered MITO(60 mg/m2)and MEL(180 mg/m2)which showed promising results.Lastly,amyloidosis was considered,and the regimen that proved to be competent was MEL 200(200 mg/m2).This review article demonstrates a comparison between various conditioning regimens employed in different diseases.
基金supported in part by the National Key Research and Development Program of China(2019YFB1503700)the Hunan Natural Science Foundation-Science and Education Joint Project(2019JJ70063)。
文摘The noise that comes from finite element simulation often causes the model to fall into the local optimal solution and over fitting during optimization of generator.Thus,this paper proposes a Gaussian Process Regression(GPR)model based on Conditional Likelihood Lower Bound Search(CLLBS)to optimize the design of the generator,which can filter the noise in the data and search for global optimization by combining the Conditional Likelihood Lower Bound Search method.Taking the efficiency optimization of 15 kW Permanent Magnet Synchronous Motor as an example.Firstly,this method uses the elementary effect analysis to choose the sensitive variables,combining the evolutionary algorithm to design the super Latin cube sampling plan;Then the generator-converter system is simulated by establishing a co-simulation platform to obtain data.A Gaussian process regression model combing the method of the conditional likelihood lower bound search is established,which combined the chi-square test to optimize the accuracy of the model globally.Secondly,after the model reaches the accuracy,the Pareto frontier is obtained through the NSGA-II algorithm by considering the maximum output torque as a constraint.Last,the constrained optimization is transformed into an unconstrained optimizing problem by introducing maximum constrained improvement expectation(CEI)optimization method based on the re-interpolation model,which cross-validated the optimization results of the Gaussian process regression model.The above method increase the efficiency of generator by 0.76%and 0.5%respectively;And this method can be used for rapid modeling and multi-objective optimization of generator systems.
文摘Objective:To analyze the effects of providing extended rehabilitation nursing services at home to patients with coronary heart disease(CHD)combined with heart failure(CHF)on psychological improvement and adherence to medical compliance behavior.Methods:79 patients with CHD with CHF admitted to Sijia Town Central Health Hospital,Haimen District,Nantong City,Jiangsu Province,between June 2021 and June 2023 were selected and grouped according to the randomized numerical table method.The control group(39 cases)was provided with conventional nursing care and extended rehabilitation nursing care at home was provided to the observation group(40 cases).The psychological status,adherence to medical behaviors,cardiac function,and complications between both groups were compared.Results:The scores of anxieties and depression self-assessment scales(SAS,SDS)of patients in the observation group were lower than those of the control group(t=2.954,3.212;P<0.05);the compliance of patients in the observation group was higher than that of the control group(P<0.05).The levels of left ventricular ejection fraction,end-systolic and end-diastolic internal diameters(LVEF,LVESD,LVEDD)of patients in the observation group at 58.02±5.34%,44.49±5.16 mm,and 49.16±5.76 mm respectively were better than those of the control group after nursing care(t=3.205,3.288,2.633;P<0.05);the complication rate of the observation group was lower than that of the control group(P<0.05).Conclusion:Extended rehabilitation nursing at home exhibited a psychological regulation effect on CHD with CHF patients,improved their medical compliance,improved cardiac function,reduced the incidence of complications,and had significant application value.
文摘Aptian is characterized by widespread deposition of organic-rich sediment.The Aptian bitumen limestone horizon,which is thin decimetre-thick sequences,locally crops out in the Kircaova area,Eastern Black Sea Region(Eastern Pontides).They are well correlated with Aptian bitumen limestone in the other Tethys Reams.They are proposed as episodes of increased organic matter.However,background factors controlling organic matter enrichment are poorly known.In this study,we present new inorganic geochemistry,including trace elements,rare earth elements(REE),redox-sensitive elements(RSE),stable-isotopes(δ~(18)O andδ~(13)C),and total organic carbon(TOC).We integrated new geochemical data with existing stratigraphy,paleontology,and organic chemistry data to provide new insight into the depositional environment and paleoclimate conditions during Aptian.The lacustrine bitumen limestone(LBL)samples have variedδ~(13)C(ave.-1.45‰)andδ~(18)O(ave.-4.50‰).They possess distinct REE patterns,with an average of REE(ave.14.45 ppm)and Y/Ho(ave.35)ratios.In addition,they have variable Nd/YbN(0.28-0.81;ave.0.56)and Ce/Ce*(0.68-0.97;ave.0.86),and relatively high Eu^(*)/Eu(1.23-1.53;ave.1.35).They display seawater signatures with reduced oxygen conditions.The enrichment in RSE(Mo,Cu,Ni,and Zn)and the low Mo/TOC(0.70-3.69;ave.2.41)support a certain degree of water restriction.The high Sr/Ba,Sr/Cu,Ga/Rb,and K/Al records of the LBL facies suggest hot house climatic conditions.The sedimentary environment was probably an isolated basin that is transformed from the marine basin.In addition to depositional conditions,the regional parameters such as the climate,increased run-off period,nutrient levels,alkalinity level,and dominant carbonate producers favored the enrichment in organic matter of LBL facies.Thus,extreme greenhouse palaeoclimate conditions have an important role in organic matter enrichment in the isolated basin.Our results are conformable with the published data from marine,semi-restricted basin,and lacustrine settings in the different parts of the Tethys margin.Thus,this approach provides the first insight into the Aptian greenhouse paleo-climate conditions of the Eastern Black Sea Region,NE Turkey.
基金The Major Projects of the National Natural Science Foundation of China under contract No.U21A6001the Program of Marine Economy Development Special Fund under Department of Natural Resources of Guangdong Province under contract No.GDNRC[2022]18+1 种基金the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.SML2021SP207the Fund of State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences under contract No.LTO2001.
文摘Reliable wave information is critical for marine engineering.Numerical wave models are useful tools to obtain wave information with continuous spatiotemporal distributions.However,the accuracy of model results highly depends on the quality of wind forcing.In this study,we utilize observations from five buoys deployed in the northern South China Sea from August to September 2017.Notably,these buoys successfully recorded wind field and wave information during the passage of five tropical cyclones of different intensities without sustaining any damage.Based on these unique observations,we evaluated the quality of four widely used wind products,namely CFSv2,ERA5,CCMP,and ERAI.Our analysis showed that in the northern South China Sea,ERA5 performed best compared to buoy observations,especially in terms of maximum wind speed values at 10 m height(U10),extreme U10 occurrence time,and overall statistical indicators.CFSv2 tended to overestimate non-extreme U10 values.CCMP showed favorable statistical performance at only three of the five buoys,but underestimated extreme U10 values at all buoys.ERAI had the worst performance under both normal and tropical cyclone conditions.In terms of wave hindcast accuracy,ERA5 outperformed the other reanalysis products,with CFSv2 and CCMP following closely.ERAI showed poor performance especially in the upper significant wave heights.Furthermore,we found that the wave hindcasts did not improve with increasing spatiotemporal resolution,with spatial resolution up to 0.5°.These findings would help in improving wave hindcasts under extreme conditions.
基金Supported by the National Natural Science Foundation of China (No.52101343)。
文摘As a type of reciprocating machine, the reciprocating compressor has a compact structure and many excitation sources.Once the small end bearing of the connecting rod is worn, it is easy to cause the sintering of the bearing and the abnormal vibration of the body.Based on the characteristics of poor lubrication state and complex force of connecting rod small head bearing, a mixed lubrication model considering oil groove feed was established, and the dynamic simulation of the reciprocating compressor model with lubricated bearings was carried out;considering different speeds and gas load conditions, the law of the impact of the eigenvalues changing with working conditions was explored.The fault simulation experiment was carried out by selecting representative working conditions, which verified the correctness of the simulation method.The study found that two contact collisions between the pin and the bearing bush occurred in one cycle, the collision impact was more severe under the wear fault, and the existence of the gap made the dynamic response more sensitive to the change of working conditions.This research provides ideas for the location and feature extraction of fault symptom signal angular segments in the process of complex measured signal processing.
基金the International Science Partnership Program of the Chinese Academy of Sciences(No.133137KYSB20200002)the Laoshan Laboratory(No.LSKJ202204005)+3 种基金the State Key Program of National Natural Science of China(No.42130411)the International Science Partnership Program of the Chinese Academy of Sciences(No.121311KYSB20190029)the Aoshan Science and Technology Innovation Program(No.2016ASKJ02-4)the Taishan Scholars Project(to Song SUN)。
文摘The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size structure in summer 2017 in the YS and ECS were assessed using ZooScan imaging analysis.Zooplankton abundance and biovolume ranged 2.94–1187.14 inds./m^(3)and 3.13–3438.51 mm^(3)/m^(3),respectively.Based on the biovolume data of the categorized size classes of 26 identified taxonomic groups,the zooplankton community was classified into five groups,and each group was coupled with distinctive oceanographic features.Under the influence of the Yellow Sea Cold Water Mass,the Yellow Sea offshore group featured the lowest bottom temperature(10.84±3.42℃)and the most abundant Calanoids(mainly in the 2–3 mm size class).In the Yellow Sea inshore group,Hydrozoans showed the largest biovolume and dominated in the 3–4-mm and>5-mm size classes.The East China Sea offshore group,which was affected by the Kuroshio Branch Current,featured high temperature and salinity,and the lowest bottom dissolved oxygen(2.58±0.5 mg/L).The lowest values of zooplankton abundance and biovolume in the East China Sea offshore group might be attributed to the bottom dissolved oxygen contents.The East China Sea inshore group,which was mainly influenced by the Zhejiang-Fujian Coastal Current and Changjiang Diluted Water,was characterized by high chlorophyll a and the largest biovolume of carnivorous Siphonophores(280.82±303.37 mm^(3)/m^(3)).The Changjiang River estuary offshore group showed the most abundant Cyclopoids,which might be associated with the less turbid water mass in this region.Seawater temperature was considered the most important factor in shaping the size compositions of Calanoids in different groups.
文摘This study was conducted to provide a preliminary assessment of the sea cucumber fishery in Aurora, Philippines. This was conducted from February to June 2013. All sea cucumber gatherers and traders, obtained through snowball sampling, in each identified sea cucumber fishery area in six coastal municipalities (Baler, Dipaculao, Dinalungan, Casiguran, Dilasag and Dingalan) were interviewed using a structured interview schedule and focused group discussions (FGD). Results revealed that gathering sea cucumbers were accomplished by handpicking, skin diving or compressor diving. A total of 15 commercial species were regularly gathered. Out of this, three species are of very high economic value (≥Php 4000/kg) (Holothuria nobilis, Holothuria scabra, and Actinopyga lecanora). The average number of kilograms harvested per hour per trip ranges from 0.21 (Holothuria fuscopunctata) to 2.71 (Holothuria scabra), while the average size of commonly gathered sea cucumber varies among species with Holothuria lecanora showed an average length (29.26 cm) greater than recorded 24 cm. Processing mainly involves washing, slicing, boiling, drying and packing. Processed sea cucumbers or trepan were sold to middlemen or direct buyers who usually offered higher prices (36.36% up to 69.20%) than the former. Problems encountered by sea cucumber gatherers and traders include a decline in total catch, a shift in area of collection from intertidal zones to deeper waters, an increase in the number of hours spent in finding and gathering sea cucumbers, the use of compressors in gathering, the decline of larger species and gathering of smaller sizes in huge amount, the absence of conservation program for sea cucumber, and the lenient implementation of government policies with regards to coastal resources management.
基金the Science and Technology Planning Project in FujianChina(No.2015N0010)+1 种基金the Science and Technology Planning Project in XiamenChina(No.3502Z20143017)。
文摘The aquaculture industry has developed significantly over the past few decades and has had a substantial impact on the global food supply and marine fisheries resources.However,some problems arise behind the scenes due to excessive intensive farming,such as slow animal growth,frequent disease,and lipid metabolism disorders.These problems have limited the sustainable development of the aquaculture industry,and a continuable solution is required.The use of fungal polysaccharide appears to provide a solution to these problems.Therefore,different supplemented levels of Poria cocos polysaccharide(PCP)(0,0.4,0.8,1.2,1.6,and 2.0 g/kg,respectively)were fed to spotted sea bass(Lateolabrax maculatus)in similar size(30.28±0.18 g)in current study.The effects of PCP on growth,physiological parameters,and lipid metabolism of spotted sea bass were investigated after a 4-week rearing period.Results showed,fish with PCP intake presented a significantly higher weight gain,specific growth rate,and a significantly lower feed conversion ratio.Significantly higher trypsin activity in liver and intestine were observed in fish with PCP intake.The superoxide dismutase activity in serum and liver of fish with PCP intake were significantly improved,while significantly higher serum total antioxidant capacity and hepatic catalase activity were also observed.However,no significant differences in lysozyme and alkaline phosphatase activity were evident among groups.Fish with PCP intake showed a significantly lower total cholesterol,but no noteworthy change in triglyceride and lipid-metabolismrelated genes expression were observed among groups.Results indicated that intake of PCP has a positive effect on growth and antioxidant capacity of spotted sea bass,but seems to have a limited effect on the non-specific immunity and lipid metabolism of spotted sea bass.Based on the regression analysis results,1.4 g/kg of PCP is the optimal dose for spotted sea bass in size(30.28±0.18 g).
基金supported by the National Natural Science Foundation of China(Nos.42076238,42176012,and 42130402)the National Key Research and Development Program of China(No.2021YFC3101702)the Shanghai Frontiers Research Center of the Hadal Biosphere.
文摘The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately 0.93.The water temperature measured from the Advanced Research and Global Observation Satellite was applied to validate the model simulation.Accordingly,the RMSE of the SST is 0.92℃ with a COR of approximately 0.99.As revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively high.The variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak SWH.Moreover,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio Current.The sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the ocean.The variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in May.Moreover,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current.
文摘The abundance, distribution and diversity of epibenthic echinoderm were investigated at Dungonab Bay in the Red Sea coastal water of the Sudan. Four permanent line transects were chosen. Eight (30 × 2) square metre belt transects along each permanent line transect at 20 metre intervals were used to collect data. The data were subjected to univariate and multivariate analyses. Spatial variations of epibenthic echinoderm abundance were assessed with one-way analysis of variance. Hierarchical agglomerative clustering was used to identify and illustrate the similarities in echinoderm abundance between line transects and between belt transects. Indices of richness (d), diversity (H'), evenness (J') and dominance (C) were used to explain the diversity of epibenthic echinoderm species. The distribution pattern of each echinoderm species was determined in each permanent line transect. A total of 986 individuals were recorded within sixteen species of epibenthic echinoderms in the four line transects. Holothuriidae was the dominant family (5 species and 342 individuals). The most abundant echinoderms species was Pearsonothuria graeffei (77 individuals, about 7.81%). Abundances intra-transects and intra-families were insignificant (f = 1.67, p = 0.183, df = 3 and f = 3.24, p = 0.083, df = 9, respectively). The highest values of Shannon-Wiener diversity index (H'), Pielou evenness index (J'), Margalef species richness index (d), and Simpson Dominance index (C) were 2.738, 0.9875, 2.791 and 0.07159, respectively. The distribution patterns of all species in the study transects varied between clumped and uniform, with the exception of Asthenosoma varium of the Echinothuridae family, which had clumped distribution patterns in all transects. The study concluded that Dungonab Bay supports rich and diverse communities of epibenthic echinoderms.
基金Supported by the Fundamental Research Funds for the Central Universities(Nos.202341017,202313024)。
文摘Chlorophyll-a(Chl-a)concentration is a primary indicator for marine environmental monitoring.The spatio-temporal variations of sea surface Chl-a concentration in the Yellow Sea(YS)and the East China Sea(ECS)in 2001-2020 were investigated by reconstructing the MODIS Level 3 products with the data interpolation empirical orthogonal function(DINEOF)method.The reconstructed results by interpolating the combined MODIS daily+8-day datasets were found better than those merely by interpolating daily or 8-day data.Chl-a concentration in the YS and the ECS reached its maximum in spring,with blooms occurring,decreased in summer and autumn,and increased in late autumn and early winter.By performing empirical orthogonal function(EOF)decomposition of the reconstructed data fields and correlation analysis with several potential environmental factors,we found that the sea surface temperature(SST)plays a significant role in the seasonal variation of Chl a,especially during spring and summer.The increase of SST in spring and the upper-layer nutrients mixed up during the last winter might favor the occurrence of spring blooms.The high sea surface temperature(SST)throughout the summer would strengthen the vertical stratification and prevent nutrients supply from deep water,resulting in low surface Chl-a concentrations.The sea surface Chl-a concentration in the YS was found decreased significantly from 2012 to 2020,which was possibly related to the Pacific Decadal Oscillation(PDO).
基金the University of French Polynesiafunding by several successive“Decision Aide a la Recherche”(DAR)grants to the Geodesy Observatory of Tahiti from the French Space Agency(CNES)+2 种基金fundings from the local government of French Polynesia(Observatoire Polynesien du Rechauffement Climatique)funding by“National Natural Science Foundation of China”(Grand No.41931075)funding by“the Fundamental Research Funds for the Central Universities"(Grand No.2042022kf1198)。
文摘In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia.
