This paper presents a novel experiment to observe the whole water entry process of a free-falling sphere into a regular wave.A time-accurate synchronizing system modulates the moment elaborately to ensure the sphere i...This paper presents a novel experiment to observe the whole water entry process of a free-falling sphere into a regular wave.A time-accurate synchronizing system modulates the moment elaborately to ensure the sphere impacting onto the water surface at the desirable wave phase.Four high-speed cameras focus locally to measure the high-precision size of the cavity evolution.Meanwhile,the aggregated field view of the camera array covers both the splash above the free surface and the entire cavity in the wave.The detailed methodologies are described and verified for the hardware set-up and the image post-processing.The theoretical maximum deviation is 1.7%on the space scale.The integral morphology of the cavity is captured precisely in the coordinate system during the sphere penetrates through the water at four representative wave phases and the still water.The result shows that the horizontal velocity of the fluid particle in the wave impels the cavity and changes the shape distinctly.Notably,the wave motion causes the cavity to pinch offearlier at the wave trough phase and later at the wave crest phase than in the still water.The wave motion influences the falling process of the sphere slightly in the present parameters.展开更多
Granular debris plays a significant role in determining damming deposit characteristics. An indepth understanding of how variations in grain size distribution(GSD) and geometric configurations impact the behavior of g...Granular debris plays a significant role in determining damming deposit characteristics. An indepth understanding of how variations in grain size distribution(GSD) and geometric configurations impact the behavior of granular debris during the occurrence of granular debris is essential for precise assessment and effective mitigation of landslide hazards in mountainous terrains. This research aims to investigate the impact of GSD and geometric configurations on sliding and damming properties through laboratory experiments. The geometric configurations were categorized into three categories based on the spatial distribution of maximum volume: located at the front(Type Ⅰ), middle(Type Ⅱ), and rear(Type Ⅲ) of the granular debris. Our experimental findings highlight that the sliding and damming processes primarily depend on the interaction among the geometric configuration, grain size, and GSD in granular debris. Different sliding and damming mechanisms across various geometric configurations induce variability in motion parameters and deposition patterns. For Type Ⅰ configurations, the front debris functions as the critical and primary driving component, with energy dissipation primarily occurring through inter-grain interactions. In contrast, Type Ⅱ configurations feature the middle debris as the dominant driving component, experiencing hindrance from the front debris and propulsion from the rear, leading to complex alterations in sliding motion. Here, energy dissipation arises from a combination of inter-grain and grain-substrate interactions. Lastly, in Type Ⅲ configurations, both the middle and rear debris serve as the main driving components, with the rear sliding debris impeded by the front. In this case, energy dissipation predominantly results from grainsubstrate interaction. Moreover, we have quantitatively demonstrated that the inverse grading in damming deposits, where coarse grain moves upward and fine grain moves downward, is primarily caused by grain sorting due to collisions among the grains and between the grain and the base. The impact of grain on the horizontal channel further aids grain sorting and contributes to inverse grading. The proposed classification of three geometric configurations in our study enhances the understanding of damming properties from the view of mechanism, which provides valuable insights for related study about damming granular debris.展开更多
In the design of wind turbine foundations for offshore wind farms, the wave load and run-up slamming on the supporting structure are the quantities that need to be considered. Because of a special arc transition, the ...In the design of wind turbine foundations for offshore wind farms, the wave load and run-up slamming on the supporting structure are the quantities that need to be considered. Because of a special arc transition, the interaction between the wave field and the composite bucket foundation(CBF) becomes complicated. In this study, the hydrodynamic characteristics, including wave pressure, load, upwelling, and run-up, around the arc transition of a CBF influenced by regular waves are investigated through physical tests at Shandong Provincial Key Laboratory of Ocean Engineering, Ocean University of China. The distributions of the wave pressures and upwelling ratios around the CBF are described, and the relationship between the wave load and the wave parameters is discussed. New formulae based on the velocity stagnation head theory with linear wave theory and the second-order Stokes wave theory for wave kinematics are proposed to estimate the wave run-up. Moreover, the multiple regression method with nonlinear technology is employed to deduce an empirical formula for predicting run-up heights. Results show that the non-dimensional wave load increases with the increase in the values of the wave scattering parameter and relative wave height. The wave upwelling height is high in front of the CBF and has the lowest value at an angle of 135? with the incoming wave direction. The performance of the new formulae proposed in this study is compared using statistical indices to demonstrate that a good fit is obtained by the multiple regression method and the analytical model based on the velocity stagnation head theory is underdeveloped.展开更多
A fault accommodation zone is a type of structure that is defined as regulating displacement and strain between faults structure.Increasing numbers of fault accommodation zones are being identified in graben basins,in...A fault accommodation zone is a type of structure that is defined as regulating displacement and strain between faults structure.Increasing numbers of fault accommodation zones are being identified in graben basins,indicating the potential exploration target and petroleum accumulation areas.This study aims to analyze the formation mechanism and development of fault accommodation zones under combined stress by a numerical simulation method considering geomechanical modeling.Using three-dimensional(3-D)seismic interpretation and fractal dimension method,exampled with the Dongxin fault zone,the fault activity and fault combination pattern were conducted to quantitatively characterize the activity difference in fault accommodation zones.Combined with mechanical experiment test,a geomehcanical model was established for fault accommodation zones in a graben basin.Integrating the paleostress numerical simulations and structural physical simulation experiment,the developmental characteristics and genetic mechanism of fault accommodation zones were summarized.Influenced by multi movements and combined stresses,three significant tectonic evolution stages of the Dongxing Fault Zone(DXFZ)were distinguished:During the E_(s)^(3)sedimentary period,the large difference in the stress,strain,and rupture distribution in various faults were significant,and this stage was the key generation period for the prototype of the DXFZ,including the FAZ between large-scale faults.During the E_(s)^(2)sedimentary period,the EW-trending symmetric with opposite dipping normal faults and the NE-SW trending faults with large scale were furtherly developed.The junction area of two secondary normal faults were prone to be ruptured,performing significant period for inheriting and developing characteristics of fault accommodation zones.During the Es1 sedimentary period,the high-order faults in the DXFZ exhibited the obvious fault depressions and strike-slip activity,and the fault accommodation zones were furtherly inherited and developed.This stage was the molded and formative period of the FAZ,the low-order faults,and the depression in the DXFZ.展开更多
If Michelson were to answer the question posed in the title, given the line of reasoning he used in 1881, Michelson would seat at his desktop computer to calculate the expected fringeshifts for several solar speeds ar...If Michelson were to answer the question posed in the title, given the line of reasoning he used in 1881, Michelson would seat at his desktop computer to calculate the expected fringeshifts for several solar speeds around 400 km/s and various directions of motion. Present author did exactly the same in 2001 to plan his repetition of Michelson and Morley’s (MM) 1887 experiment. The paper sketchedly summarizes the procedure to calculate expected fringeshifts in the MM interferometer for solar speeds available at Miller’s epoch. In a pre-relativistic context, amplitudes of several fringeshifts may be expected in both MM and Miller experiments. However, all interferometer experiments up to 1930 were designed under the (incorrect from a modern viewpoint) assumption that fringeshifts would be smaller than one fringe-width. The inescapable conclusion is that those experiments were not appropriate to measure the true value of solar motion, always yielding a small, but lower than expected, value for solar speed. The ensuing “negative” interpretation led to the birth of relativity theory and to a new series of experiments implicitly designed to test the relativistic hypothesis of length-contraction, while the earlier “positive” experiments were designed to test a different hypothesis: whether the motion of Earth relative to some preferred frame can be measured using an interferometer of constant dimensions. With the benefit of hindsight this writer repeated the MM experiment, correcting main weaknesses identified up to the Michelson-Morley-Miller (MMM) measurements at Mount Wilson from April 1925 to February 1926. A new possible reinterpretation of the MMM data as a sequence of stationary measurements is pointed out. Our Michelson-Morley-Miller-Munera (MMMM) experiment at Bogota (Colombia) from January 2003 to June 2005 gave values for solar absolute velocity in the same range as those obtained by astronomical means. Surprisingly, our results are compatible with modern third-party MM-type experiments designed and interpreted within relativistic contexts. Thus, a so far unexplored possibility arises: can interferometric experiments distinguish between pre-relativistic and relativistic theories? Our answer is negative.展开更多
The prediction of continental tight sandstone gas sweet spots is an obstacle during tight sandstone gas exploration. In this work, the classic physical fluid charging experimental equipment is improved, the combinatio...The prediction of continental tight sandstone gas sweet spots is an obstacle during tight sandstone gas exploration. In this work, the classic physical fluid charging experimental equipment is improved, the combination of the gas migration and accumulation process with the pore network numerical simulation method is investigated, and application of the permeability/porosity ratio is proposed to predict the gas saturation and sweet spots of continental formations. The results show that (1) as the charging pressure increases, the permeability of the reservoir increases because more narrow pore throats are displaced in the percolation process;and (2) based on pore network numerical simulation and theoretical analysis, the natural gas migration and accumulation mechanisms are revealed. The gas saturation of tight sandstone rock is controlled by the gas charging pressure and dynamic percolation characteristics. (3) The ratio of permeability/porosity and fluid charging pressure is proposed to predict the gas saturation of the formation. The ratio is verified in a pilot and proven to be applicable and practical. This work highlights the tight sandstone gas migration and accumulation mechanisms and narrows the gap among microscale physical experiments, numerical simulation research, and field applications.展开更多
As an important wave energy converter(WEC),the double-buoy device has advantages of wider energy absorption band and deeper water adaptability,which attract an increasing number of attentions from researchers.This pap...As an important wave energy converter(WEC),the double-buoy device has advantages of wider energy absorption band and deeper water adaptability,which attract an increasing number of attentions from researchers.This paper makes an in-depth study on double-buoy WEC,by means of the combination of model experiment and numerical simulation.The Response Amplitude Operator(RAO)and energy capture of the double-buoy under constant power take-off(PTO)damping are investigated in the model test,while the average power output and capture width ratio(CWR)are calculated by the numerical simulation to analyze the influence of the wave condition,PTO,and the geometry parameters of the device.The AQWA-Fortran united simulation sy stem,including the secondary developme nt of AQWA software coupled with the flowchart of the Fortran code,models a new dynamic system.Various viscous damping and hydraulic friction from WEC system are measured from the experimental results,and these values are added to the equation of motion.As a result,the energy loss is contained in the final numerical model the by united simulation system.Using the developed numerical model,the optimal period of energy capture is identified.The power capture reaches the maximum value under the outer buoy's natural period.The paper gives the peak value of the energy capture under the linear PTO damping force,and calculates the optimal mass ratio of the device.展开更多
A new real-time underwater equipment location method adopting an electric field induced by a standard current source is proposed.Our goals were real-time tracking and location of stationary or moving underwater equipm...A new real-time underwater equipment location method adopting an electric field induced by a standard current source is proposed.Our goals were real-time tracking and location of stationary or moving underwater equipment both in shallow and deep seas,under noisy conditions.The main features of this method are as follows:(1)a standard current source on the water surface,which can be towed by a vehicle,consisting of two electrodes,a signal generator,and a GPS unit;(2)measurement of the extremely low frequency(ELF)electric field emitted by the current source,made possible by electric field sensors on the underwater equipment;(3)position of the underwater equipment is estimated in real time based on a progressive update extended Kalman filter(PUEKF),which is carried out using the propagation model of an ELF electric field because the electric field at the position of the underwater equipment and the current source position are known.We verified the accuracy of our method and confirmed real-time location feasibility through numerical,physical scale,and real-time sea experiments.Through numerical experiments,we verified that our method works for underwater equipment location in real-world conditions,and the location error can be less than 0.2 m.Next,real-time location experiments for stationary underwater measuring equipment in water tank were conducted.The result shows that the location error can be less than 0.1 m.We also confirmed real-time location feasibility through the use of offshore experiment.We expect that our method will complement conventional underwater acoustic location methods for underwater equipment in acoustically noisy environments.展开更多
The high investment and low return of wave energy converters(WECs)seriously hamper their large-scale commercial application.The integration of WECs and floating breakwaters is conducive to enhance the competitiveness ...The high investment and low return of wave energy converters(WECs)seriously hamper their large-scale commercial application.The integration of WECs and floating breakwaters is conducive to enhance the competitiveness of wave energy conversion.The objective of this paper is to investigate the hydrodynamic performance of a WEC-breakwater integrated system combining an upstream oscillating water column(OWC)and a downstream oscillating buoy(OB)via numerical simulations and physical experiments.A nonlinear numerical wave flume using Star-CCM+software is employed to obtain calculated results,where a tiny transverse gap is set between the flume wall and the block surface to simulate a similar two-dimensional(2D)model.The corresponding physical experiments are also carried out in a practical wave flume to verified the numerical results.The comparison of the isolated and hybrid system shows that the hybrid design leads to the decreased conversion efficiency of each WEC,but improves the transmission performance of the hybrid system.The wave resonance between two devices causes the abrupt reduction of OWC efficiency and a positive correlation exists with the OB efficiency.The total efficiency of the hybrid system is raised by an optimal opening ratio,a shallow OWC draft and a short spacing distance.Except for the OWC draft,other design parameters have weak effect on the wave attenuation of the hybrid system.This paper can help understand hydrodynamics of the hybrid WECs integrated with breakwaters and improve their performances.展开更多
To address the problems of difficult leveling and poor stability of hill crawler tractors,an attitude adjustment device based on a parallel four-bar mechanism was designed,and the mechanical reasons for the sideslip i...To address the problems of difficult leveling and poor stability of hill crawler tractors,an attitude adjustment device based on a parallel four-bar mechanism was designed,and the mechanical reasons for the sideslip instability of hill crawler tractors were analyzed.On this basis,a posture adjustment mechanism based on a parallel four-bar mechanism was proposed,and the structure of the complete attitude adjustment device was designed.To ensure that this device meets the strength requirements during operation,a mechanical analysis of the key components(active rocker and slave rocker)was carried out to accommodate the load during leveling.Based on ANSYS software,a finite element simulation analysis was used to determine the maximum stress position of the active and slave rockers.Finally,to verify the accuracy of the above simulation analysis results and determine the influence rules of the lateral slope angle,longitudinal slope angle and loading quality on the abovementioned maximum stress,a physical model test bench of the attitude adjustment device was built.An orthogonal regression experiment was carried out with the maximum stresses of the active and slave rockers as the test indices.The experimental data were analyzed by Design-Expert 10 software,and the results show that the order of the primary and secondary factors influencing the maximum stress of the active rocker was the loading mass,lateral slope angle and longitudinal slope angle.The order of the factors influencing the maximum stress of the slave rocker was the longitudinal slope angle,lateral slope angle and loading mass.The active and slave rockers meet the strength requirements.This work provides technical support for the production of hill crawler tractor physical prototypes.展开更多
Phyllite fragments are essential for accumulating and generating talus slope at the toes of hillslopes,however,how they are linked to slope failure remains unknown.This paper reports the directional arrangement of phy...Phyllite fragments are essential for accumulating and generating talus slope at the toes of hillslopes,however,how they are linked to slope failure remains unknown.This paper reports the directional arrangement of phyllite fragments(DAPF)in phyllite talus slope at the eastern margin of the Tibetan Plateau.Field investigation,mathematical statistics and model experiments were performed in order to systematically understand the influencing factors,which include fragment shape,flat ratio,dip angle(α),and fine particle content(c).The results show that the quadrilateral fragmentgenerates a similar imbricate structure more easily than the triangular and rod fragments in the phyllite talus slope.Additionally,the flat phyllite fragments easily accumulate as imbricated structures on the phyllitetalus slope.When the dip angle(α)is in the range of 20°–30°,the minimum orientation ratio(P)is more than 50%,which means thatthe DAPF phenomenon is more obviousin the phyllite talus slope.For the fine particle content(c)at the same dip angle(α),the minimum orientation ratio(P)is 54%,and the minimum orientation ratio(P)correlates positively with the fine particle content(c).Therefore,compared with the homogeneous talusslope,the phyllite talusslopedisplays a special DAPF phenomenon.This study provides a valuable reference and presents novel knowledgefor risk assessment and engineering design against the phyllite talus slope failure mechanism.展开更多
There is an urgent need for high-quality and high-frequency clock generators for high-energy physics experiments.The transmission data rate exceeds 10 Gbps for a single channel in future readout electronics of silicon...There is an urgent need for high-quality and high-frequency clock generators for high-energy physics experiments.The transmission data rate exceeds 10 Gbps for a single channel in future readout electronics of silicon pixel detectors.Others,such as time measurement detectors,require a high time resolution based on the time-to-digital readout architecture.A phase-locked loop(PLL)is an essential and broadly used circuit in these applications.This study presents an application-specific integrated circuit of a low-jitter,low-power LC-tank that is PLL fabricated using 55-nm CMOS technology.It includes a 3rd-order frequency synthesis loop with a programmable bandwidth,a divide-by-2 pre-scaler,standard low-voltage differential signaling interfaces,and a current mode logic(CML)driver for clock transmissions.All the d-flip-flop dividers and phase-frequency detectors are protected from single-event upsets using the triple modular redundancy technique.The proposed VCO uses low-pass filters to suppress the noise from bias circuits.The tested LC-PLL covers a frequency locking range between 4.74 GHz and 5.92 GHz with two sub-bands.The jitter measurements of the frequency-halved clock(2.56 GHz)are less than 460 fs and 0.8 ps for the random and deterministic jitters,respectively,and a total of 7.5 ps peak-to-peak with a bit error rate of 10^(-12).The random and total jitter values for frequencies of 426 MHz and 20 MHz are less than 1.8 ps and 65 ps,respectively.The LC-PLL consumed 27 mW for the core and 73.8 mW in total.The measured results nearly coincided with the simulations and validated the analyses and tests.展开更多
Based on seismic and drilling data,the reactivation mechanism of the pre-existing basement F4 strike-slip faultin Nanpu sag and its controlling effect on hydrocarbon accumulation difference are systematically studied....Based on seismic and drilling data,the reactivation mechanism of the pre-existing basement F4 strike-slip faultin Nanpu sag and its controlling effect on hydrocarbon accumulation difference are systematically studied.By defining fault activation stages,back-stripping fault throw and physical modeling,it is found that the Nanpu No.4 structural zone formed by the Cenozoic reactivity of the F4 fault grew from south to north,with strike-slip deformation dominated in the south and extensional deformation dominated in the north.Faults in the No.4 structural zone and those in the adjacent No.2 and No.3 structural zones were different fault systems,which grew separately,contacted and connected,and finally interwove under the action of unified stress field.By constructing the identification chart of deformation mechanisms of reactivation of pre-existing faults,it is concluded that during the sedimentary period of the Paleogene Shahejie Formation,F4 fault was reactivated by strike-slip faulting,and during the sedimentary period of Paleogene Dongying Formation and Neogene Guantao-Minghuazhen formations,it was reactivated by oblique extension.The controlling effects of Cenozoic reactivation of F4 fault on hydrocarbon accumulation include:(1)As the oil-source fault,it controlled the vertical cross-layer migration of oil and gas.(2)It gave rise to strike-slip transfer zone to control the distribution of sand bodies.(3)It grew upward and interacted with faults in the neighboring area,controlling the formation of two types of traps,and was favorable for oil and gas accumulation.展开更多
Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs,nine groups of experiments were designed and performed to analyze the interference characteristics and their influenci...Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs,nine groups of experiments were designed and performed to analyze the interference characteristics and their influencing factors during water flooding.Based on percolation theory,an inversion model for simulating waterflooding interferences was proposed to study the influence laws of different factors on interference characteristics.The results show that well spacing,permeability ratio,cave size,and cave location all affect the interference characteristics of water flooding.When the cave is located in high permeability fractures,or in the small well spacing direction,or close to the producer in an injection-production unit,the effects of water flooding are much better.When the large cave is located in the high-permeability or small well spacing direction,the well in the direction with lower permeability or smaller well spacing will see water breakthrough earlier.When the cave is in the higher permeability direction and the reserves between the water injector and producer differ greatly,the conductivity differences in different injection-production directions are favorable for water flooding.When the injection-production well pattern is constructed or recombined,it’s better to make the reserves of caves in different injection-production directions proportional to permeability,and inversely proportional to the well spacing.The well close to the cave should be a producer,and the well far from the cave should be an injector.Different ratios of cave reserves to fracture reserves correspond to different optimal well spacings and optimal permeability ratios.Moreover,both optimal well spacing and optimal permeability ratio increase as the ratio of cave reserves to fracture reserves increases.展开更多
The ultra-low porosity and permeability,as well as complex occurrence and transport state of shale reservoir make it possess special L-type production characteristic curve and complicated shale gas flow mechanism.To s...The ultra-low porosity and permeability,as well as complex occurrence and transport state of shale reservoir make it possess special L-type production characteristic curve and complicated shale gas flow mechanism.To solve the difficulty of collecting complete production data due to short production time and operation discontinuity,a full-diameter core physical simulation experiment on the full lifecycle production process of shale gas well depletion is conducted with the purpose of obtaining many important production data including complete pressure and daily gas output in the simulated production process of shale gas well.The experimental results show the production characteristic from simulation is consistent with those from gas well.Based on the simulation data,the critical desorption pressure(12 MPa)of core,free gas production(3820.8 mL),adsorbed gas production(2151.2 mL),the proportion of the daily gas production between free and absorbed gas under different time and formation pressure,as well as the production time and final recovery rate corresponding to abandoned pressure,can be determined accurately.Numerical inversion is carried out to calculate the production performance curve of shale gas well and predict the development effect of gas well based on well testing and similarity analysis of the dimensionless time between core experiment and gas well production.Finally,the permeability and the fracturing effect(fracture network density)as the keys to the effective development of shale gas reservoirs are proposed.The permeability is the fundamental factor and the fracturing technology is the major means.展开更多
In this study, a simple Arduino-based experiment was designed to examine the acceleration of the object during free fall and to calculate the value of “g” (acceleration due to gravity). Experimental data on the free...In this study, a simple Arduino-based experiment was designed to examine the acceleration of the object during free fall and to calculate the value of “g” (acceleration due to gravity). Experimental data on the free fall of a plastic box through the air was gathered with the help of an ultrasonic distance sensor (HC-SR04). Readings were taken at different intervals during the fall to obtain distance time curves. Acceleration during the free fall was then determined by applying the standard kinematic equations. The shape of the distance-time graphs obtained from the experimental setup was in good agreement with the predicted graphs and the calculated values of g lie within the expected range. After repeated experiments, value of gravitational acceleration was found to be 9.805 m/s2. Hardware and software prepared for the experiment are sufficient to examine movement of ordinary objects during free fall, therefore the experiment can be easily settled in a laboratory for the purpose of learning and teaching.展开更多
In the course of the propagation of waves from the offshore to the nearshore zone, the wave may break due to the shoaling effect. Strong impact forces are observed when the breaking wave acts on the pier of the bridge...In the course of the propagation of waves from the offshore to the nearshore zone, the wave may break due to the shoaling effect. Strong impact forces are observed when the breaking wave acts on the pier of the bridge. This impact force might not only change the dynamic load pattern on the pier but also cause strong structural vibration, which may threaten the driving and structural safety of the bridge. Many studies have been carried out to study the issues in the aspect of wave flume experiment, numerical simulation, calculation of breaking wave force, and random vibration response of the structure. Considering the studies of breaking wave load on bridge piers are lack of systematic summaries, this paper presents a comprehensive and up-to-date literature review of breaking wave research and practice related to bridges. Firstly, a brief introduction is given, which includes recent cases of bridge failures caused by breaking waves. Then, both scientific and technical studies are reviewed, categorized into four aspects: experimental study, numerical simulation, analytical calculation of breaking wave force, and the structural response under breaking wave. Finally, Discussion is provided on four emerging ideas to investigate breaking wave forces on the pier from both science and engineering perspectives.展开更多
Background The China Spallation Neutron Source(CSNS)accelerator consists of an 80 MeV H-LINAC,a 1.6 GeV rapid cycling synchrotron(RCS)and two beam transport lines.The uncontrolled beam may permanently damage the compo...Background The China Spallation Neutron Source(CSNS)accelerator consists of an 80 MeV H-LINAC,a 1.6 GeV rapid cycling synchrotron(RCS)and two beam transport lines.The uncontrolled beam may permanently damage the components or lead to very high residual radiation dose along the beam line.So the equipment protection must be deliberately designed and implemented.Purpose The machine protection system(MPS)protects components from being damaged by the beam.The response time requirement for the CSNS MPS is less than 20 ms,so the PLC(programmable logic controller)was adopted to implement the interlock logic.Methods The MPS was implemented as a two-tier architecture system,and developed through utilizing PLC and Experimental Physics and Industrial Control System(EPICS)software toolkits.The application logic was taken into careful consideration during the implementation stage.An embedded CPU module can function as an IOC accessing PLC I/O modules through the sequence CPU,with an embedded Linux operation system.Results The interlock logic and heartbeat functions were tested with all functions ok.Time consumption has been measured thoroughly since the important requirement,which is around 15 ms to stop the beam.Conclusions MPS was completed in Sep.2017 and then put into operation.It has been operating smoothly for more than 3 years.MPS has played an important role in every stage of CSNS’s commissioning and operation and achieved high reliability during the user’s experiment operation.The accelerator recently runs stably with low equipment failure.展开更多
Laser target components consist of multicomponent porous and nonporous materials that are adhesively bonded together.In order to assess the extent and quantity of adhesive wicking into porous foam, micro X-ray compute...Laser target components consist of multicomponent porous and nonporous materials that are adhesively bonded together.In order to assess the extent and quantity of adhesive wicking into porous foam, micro X-ray computed tomography(CT)and image processing software have been utilized. Two different laser target configurations have been assessed in situ and volume rendered images of the distribution and quantities of adhesive have been determined for each.展开更多
基金sponsored by the National Natural Sci-ence Foundation of China(Grant Nos.12102262,U22136010 and 11632012).
文摘This paper presents a novel experiment to observe the whole water entry process of a free-falling sphere into a regular wave.A time-accurate synchronizing system modulates the moment elaborately to ensure the sphere impacting onto the water surface at the desirable wave phase.Four high-speed cameras focus locally to measure the high-precision size of the cavity evolution.Meanwhile,the aggregated field view of the camera array covers both the splash above the free surface and the entire cavity in the wave.The detailed methodologies are described and verified for the hardware set-up and the image post-processing.The theoretical maximum deviation is 1.7%on the space scale.The integral morphology of the cavity is captured precisely in the coordinate system during the sphere penetrates through the water at four representative wave phases and the still water.The result shows that the horizontal velocity of the fluid particle in the wave impels the cavity and changes the shape distinctly.Notably,the wave motion causes the cavity to pinch offearlier at the wave trough phase and later at the wave crest phase than in the still water.The wave motion influences the falling process of the sphere slightly in the present parameters.
基金support of the National Natural Science Foundation of China(U20A20111,42107189).
文摘Granular debris plays a significant role in determining damming deposit characteristics. An indepth understanding of how variations in grain size distribution(GSD) and geometric configurations impact the behavior of granular debris during the occurrence of granular debris is essential for precise assessment and effective mitigation of landslide hazards in mountainous terrains. This research aims to investigate the impact of GSD and geometric configurations on sliding and damming properties through laboratory experiments. The geometric configurations were categorized into three categories based on the spatial distribution of maximum volume: located at the front(Type Ⅰ), middle(Type Ⅱ), and rear(Type Ⅲ) of the granular debris. Our experimental findings highlight that the sliding and damming processes primarily depend on the interaction among the geometric configuration, grain size, and GSD in granular debris. Different sliding and damming mechanisms across various geometric configurations induce variability in motion parameters and deposition patterns. For Type Ⅰ configurations, the front debris functions as the critical and primary driving component, with energy dissipation primarily occurring through inter-grain interactions. In contrast, Type Ⅱ configurations feature the middle debris as the dominant driving component, experiencing hindrance from the front debris and propulsion from the rear, leading to complex alterations in sliding motion. Here, energy dissipation arises from a combination of inter-grain and grain-substrate interactions. Lastly, in Type Ⅲ configurations, both the middle and rear debris serve as the main driving components, with the rear sliding debris impeded by the front. In this case, energy dissipation predominantly results from grainsubstrate interaction. Moreover, we have quantitatively demonstrated that the inverse grading in damming deposits, where coarse grain moves upward and fine grain moves downward, is primarily caused by grain sorting due to collisions among the grains and between the grain and the base. The impact of grain on the horizontal channel further aids grain sorting and contributes to inverse grading. The proposed classification of three geometric configurations in our study enhances the understanding of damming properties from the view of mechanism, which provides valuable insights for related study about damming granular debris.
基金financially supported by the funds for the National Natural Science Foundation of China (Nos. 51509230 and 52071304)the Primary Research&Development Plan of Shandong Province (No. 2019GHY 112044)。
文摘In the design of wind turbine foundations for offshore wind farms, the wave load and run-up slamming on the supporting structure are the quantities that need to be considered. Because of a special arc transition, the interaction between the wave field and the composite bucket foundation(CBF) becomes complicated. In this study, the hydrodynamic characteristics, including wave pressure, load, upwelling, and run-up, around the arc transition of a CBF influenced by regular waves are investigated through physical tests at Shandong Provincial Key Laboratory of Ocean Engineering, Ocean University of China. The distributions of the wave pressures and upwelling ratios around the CBF are described, and the relationship between the wave load and the wave parameters is discussed. New formulae based on the velocity stagnation head theory with linear wave theory and the second-order Stokes wave theory for wave kinematics are proposed to estimate the wave run-up. Moreover, the multiple regression method with nonlinear technology is employed to deduce an empirical formula for predicting run-up heights. Results show that the non-dimensional wave load increases with the increase in the values of the wave scattering parameter and relative wave height. The wave upwelling height is high in front of the CBF and has the lowest value at an angle of 135? with the incoming wave direction. The performance of the new formulae proposed in this study is compared using statistical indices to demonstrate that a good fit is obtained by the multiple regression method and the analytical model based on the velocity stagnation head theory is underdeveloped.
基金This research was supported by the Major Scientific and Technological Projects of CNPC under grant ZD2019-183-006the National Natural Science Foundation of China(42072234).The authors would like to appreciate all the people,who supported the data,testing,and analyses.Many thanks to the anonymous reviewers,whose comments improve the quality of our manuscript.
文摘A fault accommodation zone is a type of structure that is defined as regulating displacement and strain between faults structure.Increasing numbers of fault accommodation zones are being identified in graben basins,indicating the potential exploration target and petroleum accumulation areas.This study aims to analyze the formation mechanism and development of fault accommodation zones under combined stress by a numerical simulation method considering geomechanical modeling.Using three-dimensional(3-D)seismic interpretation and fractal dimension method,exampled with the Dongxin fault zone,the fault activity and fault combination pattern were conducted to quantitatively characterize the activity difference in fault accommodation zones.Combined with mechanical experiment test,a geomehcanical model was established for fault accommodation zones in a graben basin.Integrating the paleostress numerical simulations and structural physical simulation experiment,the developmental characteristics and genetic mechanism of fault accommodation zones were summarized.Influenced by multi movements and combined stresses,three significant tectonic evolution stages of the Dongxing Fault Zone(DXFZ)were distinguished:During the E_(s)^(3)sedimentary period,the large difference in the stress,strain,and rupture distribution in various faults were significant,and this stage was the key generation period for the prototype of the DXFZ,including the FAZ between large-scale faults.During the E_(s)^(2)sedimentary period,the EW-trending symmetric with opposite dipping normal faults and the NE-SW trending faults with large scale were furtherly developed.The junction area of two secondary normal faults were prone to be ruptured,performing significant period for inheriting and developing characteristics of fault accommodation zones.During the Es1 sedimentary period,the high-order faults in the DXFZ exhibited the obvious fault depressions and strike-slip activity,and the fault accommodation zones were furtherly inherited and developed.This stage was the molded and formative period of the FAZ,the low-order faults,and the depression in the DXFZ.
文摘If Michelson were to answer the question posed in the title, given the line of reasoning he used in 1881, Michelson would seat at his desktop computer to calculate the expected fringeshifts for several solar speeds around 400 km/s and various directions of motion. Present author did exactly the same in 2001 to plan his repetition of Michelson and Morley’s (MM) 1887 experiment. The paper sketchedly summarizes the procedure to calculate expected fringeshifts in the MM interferometer for solar speeds available at Miller’s epoch. In a pre-relativistic context, amplitudes of several fringeshifts may be expected in both MM and Miller experiments. However, all interferometer experiments up to 1930 were designed under the (incorrect from a modern viewpoint) assumption that fringeshifts would be smaller than one fringe-width. The inescapable conclusion is that those experiments were not appropriate to measure the true value of solar motion, always yielding a small, but lower than expected, value for solar speed. The ensuing “negative” interpretation led to the birth of relativity theory and to a new series of experiments implicitly designed to test the relativistic hypothesis of length-contraction, while the earlier “positive” experiments were designed to test a different hypothesis: whether the motion of Earth relative to some preferred frame can be measured using an interferometer of constant dimensions. With the benefit of hindsight this writer repeated the MM experiment, correcting main weaknesses identified up to the Michelson-Morley-Miller (MMM) measurements at Mount Wilson from April 1925 to February 1926. A new possible reinterpretation of the MMM data as a sequence of stationary measurements is pointed out. Our Michelson-Morley-Miller-Munera (MMMM) experiment at Bogota (Colombia) from January 2003 to June 2005 gave values for solar absolute velocity in the same range as those obtained by astronomical means. Surprisingly, our results are compatible with modern third-party MM-type experiments designed and interpreted within relativistic contexts. Thus, a so far unexplored possibility arises: can interferometric experiments distinguish between pre-relativistic and relativistic theories? Our answer is negative.
基金supported by CNPC Scientific Research and Technology Development Project“Whole petroleum system theory and unconventional hydrocarbon accumulation mechanism”(2021DJ0101).
文摘The prediction of continental tight sandstone gas sweet spots is an obstacle during tight sandstone gas exploration. In this work, the classic physical fluid charging experimental equipment is improved, the combination of the gas migration and accumulation process with the pore network numerical simulation method is investigated, and application of the permeability/porosity ratio is proposed to predict the gas saturation and sweet spots of continental formations. The results show that (1) as the charging pressure increases, the permeability of the reservoir increases because more narrow pore throats are displaced in the percolation process;and (2) based on pore network numerical simulation and theoretical analysis, the natural gas migration and accumulation mechanisms are revealed. The gas saturation of tight sandstone rock is controlled by the gas charging pressure and dynamic percolation characteristics. (3) The ratio of permeability/porosity and fluid charging pressure is proposed to predict the gas saturation of the formation. The ratio is verified in a pilot and proven to be applicable and practical. This work highlights the tight sandstone gas migration and accumulation mechanisms and narrows the gap among microscale physical experiments, numerical simulation research, and field applications.
基金financially supported by the National Key R&D Program of China (Grant No.2018YFB1501900)the Shandong Provincial Natural Science Foundation (Grant No.ZR2021ZD23)+3 种基金Qingdao Postdoctoral Program (Grant No.QDBSH20220201015)the Fundamental Research Funds for the Central Universities (Grant No.202313031)the National Natural Science Foundation of China (Grant No.52071303)the Taishan Scholars Program of Shandong Province (Grant No.ts20190914)。
文摘As an important wave energy converter(WEC),the double-buoy device has advantages of wider energy absorption band and deeper water adaptability,which attract an increasing number of attentions from researchers.This paper makes an in-depth study on double-buoy WEC,by means of the combination of model experiment and numerical simulation.The Response Amplitude Operator(RAO)and energy capture of the double-buoy under constant power take-off(PTO)damping are investigated in the model test,while the average power output and capture width ratio(CWR)are calculated by the numerical simulation to analyze the influence of the wave condition,PTO,and the geometry parameters of the device.The AQWA-Fortran united simulation sy stem,including the secondary developme nt of AQWA software coupled with the flowchart of the Fortran code,models a new dynamic system.Various viscous damping and hydraulic friction from WEC system are measured from the experimental results,and these values are added to the equation of motion.As a result,the energy loss is contained in the final numerical model the by united simulation system.Using the developed numerical model,the optimal period of energy capture is identified.The power capture reaches the maximum value under the outer buoy's natural period.The paper gives the peak value of the energy capture under the linear PTO damping force,and calculates the optimal mass ratio of the device.
基金supported by the Youth Foundation of the National Natural Science Foundation of China(Grant No.51509252)。
文摘A new real-time underwater equipment location method adopting an electric field induced by a standard current source is proposed.Our goals were real-time tracking and location of stationary or moving underwater equipment both in shallow and deep seas,under noisy conditions.The main features of this method are as follows:(1)a standard current source on the water surface,which can be towed by a vehicle,consisting of two electrodes,a signal generator,and a GPS unit;(2)measurement of the extremely low frequency(ELF)electric field emitted by the current source,made possible by electric field sensors on the underwater equipment;(3)position of the underwater equipment is estimated in real time based on a progressive update extended Kalman filter(PUEKF),which is carried out using the propagation model of an ELF electric field because the electric field at the position of the underwater equipment and the current source position are known.We verified the accuracy of our method and confirmed real-time location feasibility through numerical,physical scale,and real-time sea experiments.Through numerical experiments,we verified that our method works for underwater equipment location in real-world conditions,and the location error can be less than 0.2 m.Next,real-time location experiments for stationary underwater measuring equipment in water tank were conducted.The result shows that the location error can be less than 0.1 m.We also confirmed real-time location feasibility through the use of offshore experiment.We expect that our method will complement conventional underwater acoustic location methods for underwater equipment in acoustically noisy environments.
基金supported by the National Natural Science Foundation of China(Grant Nos.52111530137 and 52025112)the State Key Laboratory of Ocean Engineering,China(Shanghai Jiao tong University)(Grant No.1905).
文摘The high investment and low return of wave energy converters(WECs)seriously hamper their large-scale commercial application.The integration of WECs and floating breakwaters is conducive to enhance the competitiveness of wave energy conversion.The objective of this paper is to investigate the hydrodynamic performance of a WEC-breakwater integrated system combining an upstream oscillating water column(OWC)and a downstream oscillating buoy(OB)via numerical simulations and physical experiments.A nonlinear numerical wave flume using Star-CCM+software is employed to obtain calculated results,where a tiny transverse gap is set between the flume wall and the block surface to simulate a similar two-dimensional(2D)model.The corresponding physical experiments are also carried out in a practical wave flume to verified the numerical results.The comparison of the isolated and hybrid system shows that the hybrid design leads to the decreased conversion efficiency of each WEC,but improves the transmission performance of the hybrid system.The wave resonance between two devices causes the abrupt reduction of OWC efficiency and a positive correlation exists with the OB efficiency.The total efficiency of the hybrid system is raised by an optimal opening ratio,a shallow OWC draft and a short spacing distance.Except for the OWC draft,other design parameters have weak effect on the wave attenuation of the hybrid system.This paper can help understand hydrodynamics of the hybrid WECs integrated with breakwaters and improve their performances.
基金This research was conducted at the College of Mechanical and Electronic Engineering,Northwest A&F University and was supported by the National Key Research and Development Plan Program(2016YFD0700503).
文摘To address the problems of difficult leveling and poor stability of hill crawler tractors,an attitude adjustment device based on a parallel four-bar mechanism was designed,and the mechanical reasons for the sideslip instability of hill crawler tractors were analyzed.On this basis,a posture adjustment mechanism based on a parallel four-bar mechanism was proposed,and the structure of the complete attitude adjustment device was designed.To ensure that this device meets the strength requirements during operation,a mechanical analysis of the key components(active rocker and slave rocker)was carried out to accommodate the load during leveling.Based on ANSYS software,a finite element simulation analysis was used to determine the maximum stress position of the active and slave rockers.Finally,to verify the accuracy of the above simulation analysis results and determine the influence rules of the lateral slope angle,longitudinal slope angle and loading quality on the abovementioned maximum stress,a physical model test bench of the attitude adjustment device was built.An orthogonal regression experiment was carried out with the maximum stresses of the active and slave rockers as the test indices.The experimental data were analyzed by Design-Expert 10 software,and the results show that the order of the primary and secondary factors influencing the maximum stress of the active rocker was the loading mass,lateral slope angle and longitudinal slope angle.The order of the factors influencing the maximum stress of the slave rocker was the longitudinal slope angle,lateral slope angle and loading mass.The active and slave rockers meet the strength requirements.This work provides technical support for the production of hill crawler tractor physical prototypes.
基金This study has been supported by the National Natural Science Foundation of China(Grant No.41672295)Science and Technology Project of Department of Transportation of Sichuan Province(Grant No.2015B1-1)+1 种基金Sichuan Provincial Science and Technology Plan Project(Grant No.2017JY0264)Scientific and Technological Research and Development Plan of China Railway Corporation(Grant No.P2018G047).
文摘Phyllite fragments are essential for accumulating and generating talus slope at the toes of hillslopes,however,how they are linked to slope failure remains unknown.This paper reports the directional arrangement of phyllite fragments(DAPF)in phyllite talus slope at the eastern margin of the Tibetan Plateau.Field investigation,mathematical statistics and model experiments were performed in order to systematically understand the influencing factors,which include fragment shape,flat ratio,dip angle(α),and fine particle content(c).The results show that the quadrilateral fragmentgenerates a similar imbricate structure more easily than the triangular and rod fragments in the phyllite talus slope.Additionally,the flat phyllite fragments easily accumulate as imbricated structures on the phyllitetalus slope.When the dip angle(α)is in the range of 20°–30°,the minimum orientation ratio(P)is more than 50%,which means thatthe DAPF phenomenon is more obviousin the phyllite talus slope.For the fine particle content(c)at the same dip angle(α),the minimum orientation ratio(P)is 54%,and the minimum orientation ratio(P)correlates positively with the fine particle content(c).Therefore,compared with the homogeneous talusslope,the phyllite talusslopedisplays a special DAPF phenomenon.This study provides a valuable reference and presents novel knowledgefor risk assessment and engineering design against the phyllite talus slope failure mechanism.
基金supported in part by the National Natural Science Foundation of China(Nos.12005245,12075100,and 11775244)by the Scientific and Technological Innovation Project(No.2020000165)from the Institute of High Energy Physics,Chinese Academy of Sciences+1 种基金partially funded by the Scientific Instrument Development Project of the Chinese Academy of Sciences(No.ZDKYYQ20200007)Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y201905).
文摘There is an urgent need for high-quality and high-frequency clock generators for high-energy physics experiments.The transmission data rate exceeds 10 Gbps for a single channel in future readout electronics of silicon pixel detectors.Others,such as time measurement detectors,require a high time resolution based on the time-to-digital readout architecture.A phase-locked loop(PLL)is an essential and broadly used circuit in these applications.This study presents an application-specific integrated circuit of a low-jitter,low-power LC-tank that is PLL fabricated using 55-nm CMOS technology.It includes a 3rd-order frequency synthesis loop with a programmable bandwidth,a divide-by-2 pre-scaler,standard low-voltage differential signaling interfaces,and a current mode logic(CML)driver for clock transmissions.All the d-flip-flop dividers and phase-frequency detectors are protected from single-event upsets using the triple modular redundancy technique.The proposed VCO uses low-pass filters to suppress the noise from bias circuits.The tested LC-PLL covers a frequency locking range between 4.74 GHz and 5.92 GHz with two sub-bands.The jitter measurements of the frequency-halved clock(2.56 GHz)are less than 460 fs and 0.8 ps for the random and deterministic jitters,respectively,and a total of 7.5 ps peak-to-peak with a bit error rate of 10^(-12).The random and total jitter values for frequencies of 426 MHz and 20 MHz are less than 1.8 ps and 65 ps,respectively.The LC-PLL consumed 27 mW for the core and 73.8 mW in total.The measured results nearly coincided with the simulations and validated the analyses and tests.
基金Supported by the Heilongjiang Outstanding Young Talents Support Project(140119002)Research Project of PetroChina Science and Technology Innovation Fund(2020D-5007-0108)PetroChina"14th Five-Year Plan"Science and Technology Project(2021DJ0701).
文摘Based on seismic and drilling data,the reactivation mechanism of the pre-existing basement F4 strike-slip faultin Nanpu sag and its controlling effect on hydrocarbon accumulation difference are systematically studied.By defining fault activation stages,back-stripping fault throw and physical modeling,it is found that the Nanpu No.4 structural zone formed by the Cenozoic reactivity of the F4 fault grew from south to north,with strike-slip deformation dominated in the south and extensional deformation dominated in the north.Faults in the No.4 structural zone and those in the adjacent No.2 and No.3 structural zones were different fault systems,which grew separately,contacted and connected,and finally interwove under the action of unified stress field.By constructing the identification chart of deformation mechanisms of reactivation of pre-existing faults,it is concluded that during the sedimentary period of the Paleogene Shahejie Formation,F4 fault was reactivated by strike-slip faulting,and during the sedimentary period of Paleogene Dongying Formation and Neogene Guantao-Minghuazhen formations,it was reactivated by oblique extension.The controlling effects of Cenozoic reactivation of F4 fault on hydrocarbon accumulation include:(1)As the oil-source fault,it controlled the vertical cross-layer migration of oil and gas.(2)It gave rise to strike-slip transfer zone to control the distribution of sand bodies.(3)It grew upward and interacted with faults in the neighboring area,controlling the formation of two types of traps,and was favorable for oil and gas accumulation.
基金Supported by the China National Science and Technology Major Project(2016ZX05014-003-004)
文摘Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs,nine groups of experiments were designed and performed to analyze the interference characteristics and their influencing factors during water flooding.Based on percolation theory,an inversion model for simulating waterflooding interferences was proposed to study the influence laws of different factors on interference characteristics.The results show that well spacing,permeability ratio,cave size,and cave location all affect the interference characteristics of water flooding.When the cave is located in high permeability fractures,or in the small well spacing direction,or close to the producer in an injection-production unit,the effects of water flooding are much better.When the large cave is located in the high-permeability or small well spacing direction,the well in the direction with lower permeability or smaller well spacing will see water breakthrough earlier.When the cave is in the higher permeability direction and the reserves between the water injector and producer differ greatly,the conductivity differences in different injection-production directions are favorable for water flooding.When the injection-production well pattern is constructed or recombined,it’s better to make the reserves of caves in different injection-production directions proportional to permeability,and inversely proportional to the well spacing.The well close to the cave should be a producer,and the well far from the cave should be an injector.Different ratios of cave reserves to fracture reserves correspond to different optimal well spacings and optimal permeability ratios.Moreover,both optimal well spacing and optimal permeability ratio increase as the ratio of cave reserves to fracture reserves increases.
基金The work was supported by the National Science and Technology Major Project(2016ZX05062,2017ZX05037-001).
文摘The ultra-low porosity and permeability,as well as complex occurrence and transport state of shale reservoir make it possess special L-type production characteristic curve and complicated shale gas flow mechanism.To solve the difficulty of collecting complete production data due to short production time and operation discontinuity,a full-diameter core physical simulation experiment on the full lifecycle production process of shale gas well depletion is conducted with the purpose of obtaining many important production data including complete pressure and daily gas output in the simulated production process of shale gas well.The experimental results show the production characteristic from simulation is consistent with those from gas well.Based on the simulation data,the critical desorption pressure(12 MPa)of core,free gas production(3820.8 mL),adsorbed gas production(2151.2 mL),the proportion of the daily gas production between free and absorbed gas under different time and formation pressure,as well as the production time and final recovery rate corresponding to abandoned pressure,can be determined accurately.Numerical inversion is carried out to calculate the production performance curve of shale gas well and predict the development effect of gas well based on well testing and similarity analysis of the dimensionless time between core experiment and gas well production.Finally,the permeability and the fracturing effect(fracture network density)as the keys to the effective development of shale gas reservoirs are proposed.The permeability is the fundamental factor and the fracturing technology is the major means.
文摘In this study, a simple Arduino-based experiment was designed to examine the acceleration of the object during free fall and to calculate the value of “g” (acceleration due to gravity). Experimental data on the free fall of a plastic box through the air was gathered with the help of an ultrasonic distance sensor (HC-SR04). Readings were taken at different intervals during the fall to obtain distance time curves. Acceleration during the free fall was then determined by applying the standard kinematic equations. The shape of the distance-time graphs obtained from the experimental setup was in good agreement with the predicted graphs and the calculated values of g lie within the expected range. After repeated experiments, value of gravitational acceleration was found to be 9.805 m/s2. Hardware and software prepared for the experiment are sufficient to examine movement of ordinary objects during free fall, therefore the experiment can be easily settled in a laboratory for the purpose of learning and teaching.
基金financial support from the National Natural Science Foundation of China(No.51978578)。
文摘In the course of the propagation of waves from the offshore to the nearshore zone, the wave may break due to the shoaling effect. Strong impact forces are observed when the breaking wave acts on the pier of the bridge. This impact force might not only change the dynamic load pattern on the pier but also cause strong structural vibration, which may threaten the driving and structural safety of the bridge. Many studies have been carried out to study the issues in the aspect of wave flume experiment, numerical simulation, calculation of breaking wave force, and random vibration response of the structure. Considering the studies of breaking wave load on bridge piers are lack of systematic summaries, this paper presents a comprehensive and up-to-date literature review of breaking wave research and practice related to bridges. Firstly, a brief introduction is given, which includes recent cases of bridge failures caused by breaking waves. Then, both scientific and technical studies are reviewed, categorized into four aspects: experimental study, numerical simulation, analytical calculation of breaking wave force, and the structural response under breaking wave. Finally, Discussion is provided on four emerging ideas to investigate breaking wave forces on the pier from both science and engineering perspectives.
基金supported by the National Natural Science Foundation of China(Grant Nos.11832009,12172095,and 11902085)the Natural Science Foundation of Guangdong Province(Grant No.2021A1515010320)We are also very grateful to the anonymous reviewers for their contributions.
基金the China Spallation Neutron Source project,the National Science Foundation of China(Grant Nos.11575289)the Key Laboratory of Particle Acceleration Physics&Technology and State Key Laboratory of Particle Detection and Electronics.
文摘Background The China Spallation Neutron Source(CSNS)accelerator consists of an 80 MeV H-LINAC,a 1.6 GeV rapid cycling synchrotron(RCS)and two beam transport lines.The uncontrolled beam may permanently damage the components or lead to very high residual radiation dose along the beam line.So the equipment protection must be deliberately designed and implemented.Purpose The machine protection system(MPS)protects components from being damaged by the beam.The response time requirement for the CSNS MPS is less than 20 ms,so the PLC(programmable logic controller)was adopted to implement the interlock logic.Methods The MPS was implemented as a two-tier architecture system,and developed through utilizing PLC and Experimental Physics and Industrial Control System(EPICS)software toolkits.The application logic was taken into careful consideration during the implementation stage.An embedded CPU module can function as an IOC accessing PLC I/O modules through the sequence CPU,with an embedded Linux operation system.Results The interlock logic and heartbeat functions were tested with all functions ok.Time consumption has been measured thoroughly since the important requirement,which is around 15 ms to stop the beam.Conclusions MPS was completed in Sep.2017 and then put into operation.It has been operating smoothly for more than 3 years.MPS has played an important role in every stage of CSNS’s commissioning and operation and achieved high reliability during the user’s experiment operation.The accelerator recently runs stably with low equipment failure.
文摘Laser target components consist of multicomponent porous and nonporous materials that are adhesively bonded together.In order to assess the extent and quantity of adhesive wicking into porous foam, micro X-ray computed tomography(CT)and image processing software have been utilized. Two different laser target configurations have been assessed in situ and volume rendered images of the distribution and quantities of adhesive have been determined for each.
