Hydrological models are very useful tools for evaluating water resources, and the hydroclimatic hazards associated with the water cycle. However, their calibration and validation require the use of performance criteri...Hydrological models are very useful tools for evaluating water resources, and the hydroclimatic hazards associated with the water cycle. However, their calibration and validation require the use of performance criteria which choice is not straightforward. This paper aims to evaluate the influence of the performance criteria on water balance components and water extremes using two global rainfall-runoff models (HBV and GR4J) over the Ouémé watershed at the Bonou and Savè outlets. Three (3) Efficacy criteria (Nash, coefficient of determination, and KGE) were considered for calibration and validation. The results show that the Nash criterion provides a good assessment of the simulation of the different parts of the hydrograph. KGE is better for simulating peak flows and water balance elements than other efficiency criteria. This study could serve as a basis for the choice of performance criteria in hydrological modelling.展开更多
This research explores the potential for the evaluation and prediction of earth pressure balance shield performance based on a gray system model.The research focuses on a shield tunnel excavated for Metro Line 2 in Da...This research explores the potential for the evaluation and prediction of earth pressure balance shield performance based on a gray system model.The research focuses on a shield tunnel excavated for Metro Line 2 in Dalian,China.Due to the large error between the initial geological exploration data and real strata,the project construction is extremely difficult.In view of the current situation regarding the project,a quantitative method for evaluating the tunneling efficiency was proposed using cutterhead rotation(R),advance speed(S),total thrust(F)and torque(T).A total of 80 datasets with three input parameters and one output variable(F or T)were collected from this project,and a prediction framework based gray system model was established.Based on the prediction model,five prediction schemes were set up.Through error analysis,the optimal prediction scheme was obtained from the five schemes.The parametric investigation performed indicates that the relationships between F and the three input variables in the gray system model harmonize with the theoretical explanation.The case shows that the shield tunneling performance and efficiency are improved by the tunneling parameter prediction model based on the gray system model.展开更多
Increasing renewable energy targets globally has raised the requirement for the efficient and profitable operation of solar photovoltaic(PV)systems.In light of this requirement,this paper provides a path for evaluatin...Increasing renewable energy targets globally has raised the requirement for the efficient and profitable operation of solar photovoltaic(PV)systems.In light of this requirement,this paper provides a path for evaluating the operating condition and improving the power output of the PV system in a grid integrated environment.To achieve this,different types of faults in grid-connected PV systems(GCPVs)and their impact on the energy loss associated with the electrical network are analyzed.A data-driven approach using neural networks(NNs)is proposed to achieve root cause analysis and localize the fault to the component level in the system.The localized fault condition is combined with a parallel operation of adaptive neurofuzzy inference units(ANFIUs)to develop a power mismatch-based control unit(PMCU)for improving the power output of the GCPV.To develop the proposed framework,a 10-kW single-phase GCPV is simulated for training the NN-based anomaly detection approach with 14 deviation signals.Further,the developed algorithm is combined with the PMCU implemented with the experimental setup of GCPV.The results identified 98.2%training accuracy and 43000 observations/sec prediction speed for the trained classifier,and improved power output with reduced voltage and current harmonics for the grid-connected PV operation.展开更多
Learning Management System(LMS)is an application software that is used in automation,delivery,administration,tracking,and reporting of courses and programs in educational sector.The LMS which exploits machine learning...Learning Management System(LMS)is an application software that is used in automation,delivery,administration,tracking,and reporting of courses and programs in educational sector.The LMS which exploits machine learning(ML)has the ability of accessing user data and exploit it for improving the learning experience.The recently developed artificial intelligence(AI)and ML models helps to accomplish effective performance monitoring for LMS.Among the different processes involved in ML based LMS,feature selection and classification processesfind beneficial.In this motivation,this study introduces Glowworm-based Feature Selection with Machine Learning Enabled Performance Monitoring(GSO-MFWELM)technique for LMS.The key objective of the proposed GSO-MFWELM technique is to effectually monitor the performance in LMS.The pro-posed GSO-MFWELM technique involves GSO-based feature selection techni-que to select the optimal features.Besides,Weighted Extreme Learning Machine(WELM)model is applied for classification process whereas the parameters involved in WELM model are optimallyfine-tuned with the help of May-fly Optimization(MFO)algorithm.The design of GSO and MFO techniques result in reduced computation complexity and improved classification performance.The presented GSO-MFWELM technique was validated for its performance against benchmark dataset and the results were inspected under several aspects.The simulation results established the supremacy of GSO-MFWELM technique over recent approaches with the maximum classification accuracy of 0.9589.展开更多
Large-scale dense wavelength division multiplexing(DWDM)multi-channel performance monitoring is one of the indispensable technologies for the flexible optical networks.The existing Labelbased monitoring scheme require...Large-scale dense wavelength division multiplexing(DWDM)multi-channel performance monitoring is one of the indispensable technologies for the flexible optical networks.The existing Labelbased monitoring scheme requires expensive optical demultiplexing components/equipment to avoid the influence of stimulated Raman scattering(SRS),which is not only costly and bulky,but also could not monitor the wavelength channels simultaneously.In this paper,a low-cost,high-accuracy monitoring scheme based on Optical Label Method is proposed for DWDM networks,where the optical channel power and node identification(ID),as the main monitoring targets that both can indicate or evaluate the channel connection status,could be efficiently monitored.In the scheme,a novel digital signal processing(DSP)method of SRS mitigation is proposed and demonstrated,and an asynchronous code-division multiple access(A-CDMA)based digital label encoding and decoding method is adopted to distinguish the node ID so that channel initial added node can be accurately verified,thereby wavelength connection status can be reliably monitored by combining the channel power and node ID information.The simulation results show that each wavelength channel power and node ID can be accurately monitored only by low bandwidth photoelectric detector(PD)under the condition of 80 wavelengths and 10 spans at C-band.展开更多
Strategic maintenance plays a key role in ensuring high availability and utilization of the haul trucks,and as equipment began to grow more complex towards the end of the 20th century,there was a need for a proactive ...Strategic maintenance plays a key role in ensuring high availability and utilization of the haul trucks,and as equipment began to grow more complex towards the end of the 20th century,there was a need for a proactive maintenance strategy,which led to the development of condition-based maintenance.Realtime condition monitoring(RTCM)is the ability to perform condition monitoring in real-time and has the ability to alert maintenance and operations of abnormal conditions.These alarms can be used as an indication leading to a problem,and if a suitable corrective action is initiated in time,it could result in significant savings of equipment downtime and repair costs.This study aims to compare some maintenance performance indicators prior to and after implementation of RTCM strategy at a mine site using some tests of statistical significance.The study also indicated the presence of seasonality in the data,and thus the data was deseasonalized and detrended prior to being subjected to the statistical tests.Finally,the results indicated that RTCM strategy has proven to be successful in improving the availability for some of the failure categories chosen in this study.展开更多
A statistic-based benchmark was proposed for performance assessment and monitoring of model predic- tive control; the benchmark was straightforward and achievable by recording a set of output data only when the contro...A statistic-based benchmark was proposed for performance assessment and monitoring of model predic- tive control; the benchmark was straightforward and achievable by recording a set of output data only when the control performance was good according to the user’s selection. Principal component model was built and an auto- regressive moving average filter was identified to monitor the performance; an improved T2 statistic was selected as the performance monitor index. When performance changes were detected, diagnosis was done by model validation using recursive analysis and generalized likelihood ratio (GLR) method. This distinguished the fact that the per- formance change was due to plant model mismatch or due to disturbance term. Simulation was done about a heavy oil fractionator system and good results were obtained. The diagnosis result was helpful for the operator to improve the system performance.展开更多
The energy efficiency monitoring is an essential precondition for ground source heat pump system's controlling and energy saving operation. Based on the data monitoring applied in the school building, this work is...The energy efficiency monitoring is an essential precondition for ground source heat pump system's controlling and energy saving operation. Based on the data monitoring applied in the school building, this work is focused on the parameters acquisition and operation analysis of the GSHP system in Tangshan. Results show the average COPs(coefficient of performance) are2.85 and 2.70 in summer and winter, respectively, and heat(cold) unbalance underground existed after whole year operation. The analysis of data also indicates that the direct borehole air-conditioning saved some power consumption obviously in the early stage of summer and energy saving of the GSHP system depended remarkably on its operation and management level. Besides the observation points of ground temperature are laid for a large-scale GSHP system, and the hydraulic balance of the pipes group needs to be concerned specially in safeguarding better reliability.展开更多
The fatigue of concrete structures will gradually appear after being subjected to alternating loads for a long time,and the accidents caused by fatigue failure of bridge structures also appear from time to time.Aiming...The fatigue of concrete structures will gradually appear after being subjected to alternating loads for a long time,and the accidents caused by fatigue failure of bridge structures also appear from time to time.Aiming at the problem of degradation of long-span continuous rigid frame bridges due to fatigue and environmental effects,this paper suggests a method to analyze the fatigue degradation mechanism of this type of bridge,which combines long-term in-site monitoring data collected by the health monitoring system(HMS)and fatigue theory.In the paper,the authors mainly carry out the research work in the following aspects:First of all,a long-span continuous rigid frame bridge installed with HMS is used as an example,and a large amount of health monitoring data have been acquired,which can provide efficient information for fatigue in terms of equivalent stress range and cumulative number of stress cycles;next,for calculating the cumulative fatigue damage of the bridge structure,fatigue stress spectrum got by rain flow counting method,S-N curves and damage criteria are used for fatigue damage analysis.Moreover,it was considered a linear accumulation damage through the Palmgren-Miner rule for the counting of stress cycles.The health monitoring data are adopted to obtain fatigue stress data and the rain flow counting method is used to count the amplitude varying fatigue stress.The proposed fatigue reliability approach in the paper can estimate the fatigue damage degree and its evolution law of bridge structures well,and also can help bridge engineers do the assessment of future service duration.展开更多
Some principles and methods for the dynamic monitoring of forage-livestock bal-ance in the grazing system on the temperate grassland of China were discussed in thispaper. To prepare a dynamic monitoring system or the ...Some principles and methods for the dynamic monitoring of forage-livestock bal-ance in the grazing system on the temperate grassland of China were discussed in thispaper. To prepare a dynamic monitoring system or the forage livestock balance of grazingrangeland system, the following theoretical bases will be observed in this work.展开更多
Energy intake prepartum is critically important to health,milk performance,and profitability of dairy cows.The objective of this study was to determine the effect of reduced energy density of close-up diets on dry mat...Energy intake prepartum is critically important to health,milk performance,and profitability of dairy cows.The objective of this study was to determine the effect of reduced energy density of close-up diets on dry matter intake(DMI),lactation performance and energy balance(EB) in multiparous Holstein cows which were housed in a free-stall bam and fed for ad libitum intake.Thirty-nine dry cows were blocked and assigned randomly to three groups fed a high energy density diet[HD,n = 13;6.8 MJ of net energy for lactation(NE_L)/kg;14.0%crude protein(CP)],or a middle energy density diet(MD,n = 13;6.2 MJ NE_L/kg;14.0%CP),or a low energy density diet(LD,n = 13;5.4 MJ NE_L/kg;14.0%CP) from d 21 before expected day of calving.After parturition,all cows were fed the same lactation diet to d 70 in milk(DIM).The DMI and NE_L intake prepartum were decreased by the reduced energy density diets(P< 0.05).The LD group consumed 1.3 kg/d(DM) more diet compared with HD group in the last 24 h before calving.The milk yield and the postpartum DMI were increased by the reduced energy density diet prepartum(P< 0.05).The changes in BCS and BW prepartum and postpartum were not affected by prepartum diets.HD group had higher milk fat content and lower lactose content compared with LD group during the first 3 wk of lactation(P< 0.05).The energy consumption for HD,MD and LD groups were 149.8%,126.2%and 101.1%of their calculated energy requirements prepartum(P< 0.05),and 72.7%,73.1%and 75.2%during the first 4 wk postpartum,respectively.In conclusion,the low energy density prepartum diet was effective in controlling NE_L intake prepartum,and was beneficial in increasing DMI and milk yield,and alleviating negative EB postpartum.展开更多
An understanding of the influence of contractor monitoring on performance of road infrastructural projects in Uganda provided an impetus for this study. The objectives of the study were to: assess the relationship bet...An understanding of the influence of contractor monitoring on performance of road infrastructural projects in Uganda provided an impetus for this study. The objectives of the study were to: assess the relationship between contractors monitoring and performance of national road infrastructure projects and the relationship between contractor monitoring components and performance of national road infrastructure projects in Uganda. Purposive sampling was employed in selecting the procurement professionals, engineers and simple random sampling was adopted in selecting private consultants, members of parliament and respondents from the civil society organizations. Data for this study were collected using a closed ended questionnaire and interviews. Some of the major finding from this study include: weak procurement rules which lead to awarding road projects to incompetent contractors;contractor monitoring being handled by unqualified, incompetent and inexperienced professionals;lack of contractors and contract supervisors appraisal system;delay of contractors payments which affects timelines in services delivery;lack of a strong internal project monitoring and evaluation mechanism at the Uganda National Roads Agency (UNRA). The research therefore recommends the establishment of an Independent Public Infrastructure Development and Monitoring Unit by government and adoption of systems that appraise both contractors and contract supervisors with clear disciplinary actions for unsatisfactory performance by the UNRA.展开更多
Implementing a CO2 flooding scheme successfully requires the capacity to get accurate information of reservoir dynamic performance and fluids injected. Despite some numerical simulation studies, the complicated drive ...Implementing a CO2 flooding scheme successfully requires the capacity to get accurate information of reservoir dynamic performance and fluids injected. Despite some numerical simulation studies, the complicated drive mechanisms and actual reservoir performance have not been fully understood. There is a strong need to develop models from different perspectives to complement current simulators and provide valuable insights into the reservoir performance during CO2 flooding. The aim of this study is to develop a model by using an improved material balance equation (MBE) to analyze quickly the performance of CO2 flooding. After matching the historical field data the proposed model can be used to evaluate, monitor and predict the overall reservoir dynamic performance during CO2 flooding. In order to account accurately for the complex displacement process involving compositional effect and multiphase flow, the PVT properties and flowability of reservoir fluids are incorporated in the model. This study investigates the effects of a number of factors, such as reservoir pressure, the amount of CO2 injected, the CO2 partition ratios in reservoir fluids, the possibility of the existence of a free CO2 gas cap, the proportion of reservoir fluids contacted with CO2, the starting time of CO2 flooding, oil swelling, and oil flowability improvement by mixing with CO2. The model was used to analyze the CO2 flooding project in Weyburn oil field, Saskatchewan, Canada. This study shows that the proposed model is an effective complementary tool to analyze and monitor the overall reservoir performance during CO2 flooding.展开更多
The effects of supplemental carbohydrate (CHO) sources on milk yield and composition, nitrogen (N) balance,and ruminal fermentation were evaluated in lactating dairy cows fed energy-deficient total mixed rations (TMR)...The effects of supplemental carbohydrate (CHO) sources on milk yield and composition, nitrogen (N) balance,and ruminal fermentation were evaluated in lactating dairy cows fed energy-deficient total mixed rations (TMR) . Fifty-six lactating Holstein cows (36. 8 ± 3. 4 kg / d of milk yield; 152 ± 26 days in milk [DIM]) were randomly assigned to one of four diets: (1) basal TMR (control) ; (2) basal TMR + 1. 25 kg / d sucrose (SUC) ; (3) basal TMR + 2. 12 kg /d steam-flaked corn (SFC) ; (4) basal TMR + 2. 23 kg / d wheat (WHE) . The trial lasted 70 days,including the first 10 days of adaptation. Simultaneously, a 4 × 4 Latin square trial was conducted with four ruminally cannulated cows of similar DMI (Dry Matter Intake) fed on the above four diets. Each testing period lasted 18 days: 15 days for adaptation and 3 days for sampling. Cows fed SUC-,SFC-,and WHE-supplemented diets produced 1. 6,2. 9,and 0. 8 kg / d,respectively,more milk than those on the basal TMR control diet,but the difference was not significant (P = 0. 160) . However,the production of energy-corrected milk of cows fed CHO-supplemented diets improved significantly (P = 0. 020) ,and the yield of 4% fatcorrected milk tended to be higher (P = 0. 063) than in control animals. Percentages of milk protein,lactoseand solids-not-fat (SNF) increased significantly in cows fed CHO-supplemented diets (P < 0. 05) ,and yields of milk protein and SNF were significantly higher (P <0. 05) ; yields of milk fat and lactose were somewhat higher (P < 0. 10) . Cows receiving supplementary CHO diets consumed more DM (Dry Matter) (P = 0. 023) ; however,there was no significant difference in N retention,digestibility,or utilization efficiency among the treatments (P > 0. 10) . The average ruminal pH was lowest in cows supplemented with SUC,while that in cows supplemented with SFC and WHE was only slightly reduced (P = 0. 025) . Ruminal NH 3 -N concentration was highest with no supplementary CHO (P = 0. 017) ,and changes in postfeeding time were similar across the diets. Total volatile fatty acid concentration was significantly lower in control animals than in those on SUCand WHE-supplemented diets (P = 0. 001) ; significant dietary responses were observed in the concentrations of acetate,butyrate,and branchedchain fatty acids and in the acetate-to-propionate ratio (P <0. 001) . These results indicate that supplementation with different CHO sources in energy-deficient diets substantially improved the balance of energy and N in the rumen,altered ruminal fermentation,and improved lactation performance in dairy cows.展开更多
Background:Patients undergoing hemodialysis suffer from deteriorating physical health,impaired physical function,and have a low quality of life,that explained by insufficient metabolic clearance.To overcome these obst...Background:Patients undergoing hemodialysis suffer from deteriorating physical health,impaired physical function,and have a low quality of life,that explained by insufficient metabolic clearance.To overcome these obstacles,cost-effective strategies must be developed,including exercise as a complement to hemodialysis therapy.Objective:To determine the effectiveness of exercise therapy on functional balance,physical performance,and quality of life among patients undergoing hemodialysis:a randomized controlled trial.Methods:This randomized controlled trial study was carried out on 68 patients with chronic kidney disease undergoing hemodialysis for at least six months and had a medically stable condition who were randomly divided into training(n=32)exercise therapy and(n=31)control,groups.The training group participated in 8-week(3 sessions per week)resistance exercise therapy in three sets of 10 repetitions of knee extension,hip flexion,and hip abduction with the use of an elastic band under the supervision of a training physiotherapist and researcher during the first hour of the three routine hemodialysis treatment session per week.But the control group did not experience any intervention.To analyze the data,two-way analysis of variance and Bonferroni statistical tests were used at the significant level of(P=0.05).Results:6 Minute-Walk Test(6MWT)(0.013),and in the Physical Activity Scale for the Elderly(PASE)(0.014),and Short Survey Form 36(SF-36)questionnaires and health-related quality of life(HRQOL)(0.001)had significant improvements in the training group in comparison to the control group from pre to post-test,also physical performance(0.001)was improving as compared with control group(0.89)at(P=0.05).Conclusion:Resistance exercise therapy interventions for eight weeks effectively improve the physical function and performance,activity levels,and health-related quality of life of patients with chronic kidney disease and undergoing regular hemodialysis compared with a control group.展开更多
Performance of quality monitor models in spot welding determines the monitor precision directly, so it’s crucial to evaluate it. Previously, mean square error (MSE) is often used to evaluate performances of models, b...Performance of quality monitor models in spot welding determines the monitor precision directly, so it’s crucial to evaluate it. Previously, mean square error (MSE) is often used to evaluate performances of models, but it can only show the total errors of finite specimens of models, and cannot show whether the quality information inferred from models are accurate and reliable enough or not. For this reason, by means of measure error theory, a new way to evaluate the performances of models according to the error distributions is developed as follows: Only if correct and precise enough the error distribution of model is, the quality information inferred from model is accurate and reliable.展开更多
文摘Hydrological models are very useful tools for evaluating water resources, and the hydroclimatic hazards associated with the water cycle. However, their calibration and validation require the use of performance criteria which choice is not straightforward. This paper aims to evaluate the influence of the performance criteria on water balance components and water extremes using two global rainfall-runoff models (HBV and GR4J) over the Ouémé watershed at the Bonou and Savè outlets. Three (3) Efficacy criteria (Nash, coefficient of determination, and KGE) were considered for calibration and validation. The results show that the Nash criterion provides a good assessment of the simulation of the different parts of the hydrograph. KGE is better for simulating peak flows and water balance elements than other efficiency criteria. This study could serve as a basis for the choice of performance criteria in hydrological modelling.
基金support by the National Natural Science Foundation of China(Grant Nos.52108377,52090084,and 51938008).
文摘This research explores the potential for the evaluation and prediction of earth pressure balance shield performance based on a gray system model.The research focuses on a shield tunnel excavated for Metro Line 2 in Dalian,China.Due to the large error between the initial geological exploration data and real strata,the project construction is extremely difficult.In view of the current situation regarding the project,a quantitative method for evaluating the tunneling efficiency was proposed using cutterhead rotation(R),advance speed(S),total thrust(F)and torque(T).A total of 80 datasets with three input parameters and one output variable(F or T)were collected from this project,and a prediction framework based gray system model was established.Based on the prediction model,five prediction schemes were set up.Through error analysis,the optimal prediction scheme was obtained from the five schemes.The parametric investigation performed indicates that the relationships between F and the three input variables in the gray system model harmonize with the theoretical explanation.The case shows that the shield tunneling performance and efficiency are improved by the tunneling parameter prediction model based on the gray system model.
基金Funding for this study was received from the Deputyship for Research&Innovation,Ministry of Education in Saudi Arabia through the project number“IFPHI-021–135–2020”and King Abdulaziz University,DSR,Jeddah,Saudi Arabia.
文摘Increasing renewable energy targets globally has raised the requirement for the efficient and profitable operation of solar photovoltaic(PV)systems.In light of this requirement,this paper provides a path for evaluating the operating condition and improving the power output of the PV system in a grid integrated environment.To achieve this,different types of faults in grid-connected PV systems(GCPVs)and their impact on the energy loss associated with the electrical network are analyzed.A data-driven approach using neural networks(NNs)is proposed to achieve root cause analysis and localize the fault to the component level in the system.The localized fault condition is combined with a parallel operation of adaptive neurofuzzy inference units(ANFIUs)to develop a power mismatch-based control unit(PMCU)for improving the power output of the GCPV.To develop the proposed framework,a 10-kW single-phase GCPV is simulated for training the NN-based anomaly detection approach with 14 deviation signals.Further,the developed algorithm is combined with the PMCU implemented with the experimental setup of GCPV.The results identified 98.2%training accuracy and 43000 observations/sec prediction speed for the trained classifier,and improved power output with reduced voltage and current harmonics for the grid-connected PV operation.
基金supported by the Researchers Supporting Program(TUMA-Project2021-27)Almaarefa University,RiyadhSaudi Arabia.Taif University Researchers Supporting Project number(TURSP-2020/161)Taif University,Taif,Saudi Arabia.
文摘Learning Management System(LMS)is an application software that is used in automation,delivery,administration,tracking,and reporting of courses and programs in educational sector.The LMS which exploits machine learning(ML)has the ability of accessing user data and exploit it for improving the learning experience.The recently developed artificial intelligence(AI)and ML models helps to accomplish effective performance monitoring for LMS.Among the different processes involved in ML based LMS,feature selection and classification processesfind beneficial.In this motivation,this study introduces Glowworm-based Feature Selection with Machine Learning Enabled Performance Monitoring(GSO-MFWELM)technique for LMS.The key objective of the proposed GSO-MFWELM technique is to effectually monitor the performance in LMS.The pro-posed GSO-MFWELM technique involves GSO-based feature selection techni-que to select the optimal features.Besides,Weighted Extreme Learning Machine(WELM)model is applied for classification process whereas the parameters involved in WELM model are optimallyfine-tuned with the help of May-fly Optimization(MFO)algorithm.The design of GSO and MFO techniques result in reduced computation complexity and improved classification performance.The presented GSO-MFWELM technique was validated for its performance against benchmark dataset and the results were inspected under several aspects.The simulation results established the supremacy of GSO-MFWELM technique over recent approaches with the maximum classification accuracy of 0.9589.
基金supported by the National Natural Science Foundation of China(No.62001045)Fund of State Key Laboratory of IPOC(BUPT)(No.IPOC2021ZT17)。
文摘Large-scale dense wavelength division multiplexing(DWDM)multi-channel performance monitoring is one of the indispensable technologies for the flexible optical networks.The existing Labelbased monitoring scheme requires expensive optical demultiplexing components/equipment to avoid the influence of stimulated Raman scattering(SRS),which is not only costly and bulky,but also could not monitor the wavelength channels simultaneously.In this paper,a low-cost,high-accuracy monitoring scheme based on Optical Label Method is proposed for DWDM networks,where the optical channel power and node identification(ID),as the main monitoring targets that both can indicate or evaluate the channel connection status,could be efficiently monitored.In the scheme,a novel digital signal processing(DSP)method of SRS mitigation is proposed and demonstrated,and an asynchronous code-division multiple access(A-CDMA)based digital label encoding and decoding method is adopted to distinguish the node ID so that channel initial added node can be accurately verified,thereby wavelength connection status can be reliably monitored by combining the channel power and node ID information.The simulation results show that each wavelength channel power and node ID can be accurately monitored only by low bandwidth photoelectric detector(PD)under the condition of 80 wavelengths and 10 spans at C-band.
文摘Strategic maintenance plays a key role in ensuring high availability and utilization of the haul trucks,and as equipment began to grow more complex towards the end of the 20th century,there was a need for a proactive maintenance strategy,which led to the development of condition-based maintenance.Realtime condition monitoring(RTCM)is the ability to perform condition monitoring in real-time and has the ability to alert maintenance and operations of abnormal conditions.These alarms can be used as an indication leading to a problem,and if a suitable corrective action is initiated in time,it could result in significant savings of equipment downtime and repair costs.This study aims to compare some maintenance performance indicators prior to and after implementation of RTCM strategy at a mine site using some tests of statistical significance.The study also indicated the presence of seasonality in the data,and thus the data was deseasonalized and detrended prior to being subjected to the statistical tests.Finally,the results indicated that RTCM strategy has proven to be successful in improving the availability for some of the failure categories chosen in this study.
基金Supported by the National Natural Science Foundation of China (Nos.60474051, 60534020), the Key Technology and Devel-opment Program of Shanghai Science and Technology Department (No.04DZ11008), and the Program for New Century Ex-cellent Talents in the University of China (NCET).
文摘A statistic-based benchmark was proposed for performance assessment and monitoring of model predic- tive control; the benchmark was straightforward and achievable by recording a set of output data only when the control performance was good according to the user’s selection. Principal component model was built and an auto- regressive moving average filter was identified to monitor the performance; an improved T2 statistic was selected as the performance monitor index. When performance changes were detected, diagnosis was done by model validation using recursive analysis and generalized likelihood ratio (GLR) method. This distinguished the fact that the per- formance change was due to plant model mismatch or due to disturbance term. Simulation was done about a heavy oil fractionator system and good results were obtained. The diagnosis result was helpful for the operator to improve the system performance.
基金Project(2012BAJ06B04)supported by"12th Five-Year Plan"National science and Technology,ChinaProject(2014-228)supported by Department of Housing and Urban Rural Development of Hebei,China
文摘The energy efficiency monitoring is an essential precondition for ground source heat pump system's controlling and energy saving operation. Based on the data monitoring applied in the school building, this work is focused on the parameters acquisition and operation analysis of the GSHP system in Tangshan. Results show the average COPs(coefficient of performance) are2.85 and 2.70 in summer and winter, respectively, and heat(cold) unbalance underground existed after whole year operation. The analysis of data also indicates that the direct borehole air-conditioning saved some power consumption obviously in the early stage of summer and energy saving of the GSHP system depended remarkably on its operation and management level. Besides the observation points of ground temperature are laid for a large-scale GSHP system, and the hydraulic balance of the pipes group needs to be concerned specially in safeguarding better reliability.
文摘The fatigue of concrete structures will gradually appear after being subjected to alternating loads for a long time,and the accidents caused by fatigue failure of bridge structures also appear from time to time.Aiming at the problem of degradation of long-span continuous rigid frame bridges due to fatigue and environmental effects,this paper suggests a method to analyze the fatigue degradation mechanism of this type of bridge,which combines long-term in-site monitoring data collected by the health monitoring system(HMS)and fatigue theory.In the paper,the authors mainly carry out the research work in the following aspects:First of all,a long-span continuous rigid frame bridge installed with HMS is used as an example,and a large amount of health monitoring data have been acquired,which can provide efficient information for fatigue in terms of equivalent stress range and cumulative number of stress cycles;next,for calculating the cumulative fatigue damage of the bridge structure,fatigue stress spectrum got by rain flow counting method,S-N curves and damage criteria are used for fatigue damage analysis.Moreover,it was considered a linear accumulation damage through the Palmgren-Miner rule for the counting of stress cycles.The health monitoring data are adopted to obtain fatigue stress data and the rain flow counting method is used to count the amplitude varying fatigue stress.The proposed fatigue reliability approach in the paper can estimate the fatigue damage degree and its evolution law of bridge structures well,and also can help bridge engineers do the assessment of future service duration.
文摘Some principles and methods for the dynamic monitoring of forage-livestock bal-ance in the grazing system on the temperate grassland of China were discussed in thispaper. To prepare a dynamic monitoring system or the forage livestock balance of grazingrangeland system, the following theoretical bases will be observed in this work.
基金Supported by National Basic Research Program of China（973 Program）（2013CB035500） National Natural Science Foundation of China（61233004,61221003,61074061）+1 种基金 International Cooperation Program of Shanghai Science and Technology Commission （12230709600） the Higher Education Research Fund for the Doctoral Program of China（20120073130006）
基金financially supported by National Natural Science Foundation of China(31272469,31372334)China Agriculture Research System(CARS-37)
文摘Energy intake prepartum is critically important to health,milk performance,and profitability of dairy cows.The objective of this study was to determine the effect of reduced energy density of close-up diets on dry matter intake(DMI),lactation performance and energy balance(EB) in multiparous Holstein cows which were housed in a free-stall bam and fed for ad libitum intake.Thirty-nine dry cows were blocked and assigned randomly to three groups fed a high energy density diet[HD,n = 13;6.8 MJ of net energy for lactation(NE_L)/kg;14.0%crude protein(CP)],or a middle energy density diet(MD,n = 13;6.2 MJ NE_L/kg;14.0%CP),or a low energy density diet(LD,n = 13;5.4 MJ NE_L/kg;14.0%CP) from d 21 before expected day of calving.After parturition,all cows were fed the same lactation diet to d 70 in milk(DIM).The DMI and NE_L intake prepartum were decreased by the reduced energy density diets(P< 0.05).The LD group consumed 1.3 kg/d(DM) more diet compared with HD group in the last 24 h before calving.The milk yield and the postpartum DMI were increased by the reduced energy density diet prepartum(P< 0.05).The changes in BCS and BW prepartum and postpartum were not affected by prepartum diets.HD group had higher milk fat content and lower lactose content compared with LD group during the first 3 wk of lactation(P< 0.05).The energy consumption for HD,MD and LD groups were 149.8%,126.2%and 101.1%of their calculated energy requirements prepartum(P< 0.05),and 72.7%,73.1%and 75.2%during the first 4 wk postpartum,respectively.In conclusion,the low energy density prepartum diet was effective in controlling NE_L intake prepartum,and was beneficial in increasing DMI and milk yield,and alleviating negative EB postpartum.
文摘An understanding of the influence of contractor monitoring on performance of road infrastructural projects in Uganda provided an impetus for this study. The objectives of the study were to: assess the relationship between contractors monitoring and performance of national road infrastructure projects and the relationship between contractor monitoring components and performance of national road infrastructure projects in Uganda. Purposive sampling was employed in selecting the procurement professionals, engineers and simple random sampling was adopted in selecting private consultants, members of parliament and respondents from the civil society organizations. Data for this study were collected using a closed ended questionnaire and interviews. Some of the major finding from this study include: weak procurement rules which lead to awarding road projects to incompetent contractors;contractor monitoring being handled by unqualified, incompetent and inexperienced professionals;lack of contractors and contract supervisors appraisal system;delay of contractors payments which affects timelines in services delivery;lack of a strong internal project monitoring and evaluation mechanism at the Uganda National Roads Agency (UNRA). The research therefore recommends the establishment of an Independent Public Infrastructure Development and Monitoring Unit by government and adoption of systems that appraise both contractors and contract supervisors with clear disciplinary actions for unsatisfactory performance by the UNRA.
文摘Implementing a CO2 flooding scheme successfully requires the capacity to get accurate information of reservoir dynamic performance and fluids injected. Despite some numerical simulation studies, the complicated drive mechanisms and actual reservoir performance have not been fully understood. There is a strong need to develop models from different perspectives to complement current simulators and provide valuable insights into the reservoir performance during CO2 flooding. The aim of this study is to develop a model by using an improved material balance equation (MBE) to analyze quickly the performance of CO2 flooding. After matching the historical field data the proposed model can be used to evaluate, monitor and predict the overall reservoir dynamic performance during CO2 flooding. In order to account accurately for the complex displacement process involving compositional effect and multiphase flow, the PVT properties and flowability of reservoir fluids are incorporated in the model. This study investigates the effects of a number of factors, such as reservoir pressure, the amount of CO2 injected, the CO2 partition ratios in reservoir fluids, the possibility of the existence of a free CO2 gas cap, the proportion of reservoir fluids contacted with CO2, the starting time of CO2 flooding, oil swelling, and oil flowability improvement by mixing with CO2. The model was used to analyze the CO2 flooding project in Weyburn oil field, Saskatchewan, Canada. This study shows that the proposed model is an effective complementary tool to analyze and monitor the overall reservoir performance during CO2 flooding.
基金supported by an earmarked fund for the Modern Agro-industry Technology Research System and National Natural Science Foundation of China (30901030)
文摘The effects of supplemental carbohydrate (CHO) sources on milk yield and composition, nitrogen (N) balance,and ruminal fermentation were evaluated in lactating dairy cows fed energy-deficient total mixed rations (TMR) . Fifty-six lactating Holstein cows (36. 8 ± 3. 4 kg / d of milk yield; 152 ± 26 days in milk [DIM]) were randomly assigned to one of four diets: (1) basal TMR (control) ; (2) basal TMR + 1. 25 kg / d sucrose (SUC) ; (3) basal TMR + 2. 12 kg /d steam-flaked corn (SFC) ; (4) basal TMR + 2. 23 kg / d wheat (WHE) . The trial lasted 70 days,including the first 10 days of adaptation. Simultaneously, a 4 × 4 Latin square trial was conducted with four ruminally cannulated cows of similar DMI (Dry Matter Intake) fed on the above four diets. Each testing period lasted 18 days: 15 days for adaptation and 3 days for sampling. Cows fed SUC-,SFC-,and WHE-supplemented diets produced 1. 6,2. 9,and 0. 8 kg / d,respectively,more milk than those on the basal TMR control diet,but the difference was not significant (P = 0. 160) . However,the production of energy-corrected milk of cows fed CHO-supplemented diets improved significantly (P = 0. 020) ,and the yield of 4% fatcorrected milk tended to be higher (P = 0. 063) than in control animals. Percentages of milk protein,lactoseand solids-not-fat (SNF) increased significantly in cows fed CHO-supplemented diets (P < 0. 05) ,and yields of milk protein and SNF were significantly higher (P <0. 05) ; yields of milk fat and lactose were somewhat higher (P < 0. 10) . Cows receiving supplementary CHO diets consumed more DM (Dry Matter) (P = 0. 023) ; however,there was no significant difference in N retention,digestibility,or utilization efficiency among the treatments (P > 0. 10) . The average ruminal pH was lowest in cows supplemented with SUC,while that in cows supplemented with SFC and WHE was only slightly reduced (P = 0. 025) . Ruminal NH 3 -N concentration was highest with no supplementary CHO (P = 0. 017) ,and changes in postfeeding time were similar across the diets. Total volatile fatty acid concentration was significantly lower in control animals than in those on SUCand WHE-supplemented diets (P = 0. 001) ; significant dietary responses were observed in the concentrations of acetate,butyrate,and branchedchain fatty acids and in the acetate-to-propionate ratio (P <0. 001) . These results indicate that supplementation with different CHO sources in energy-deficient diets substantially improved the balance of energy and N in the rumen,altered ruminal fermentation,and improved lactation performance in dairy cows.
文摘Background:Patients undergoing hemodialysis suffer from deteriorating physical health,impaired physical function,and have a low quality of life,that explained by insufficient metabolic clearance.To overcome these obstacles,cost-effective strategies must be developed,including exercise as a complement to hemodialysis therapy.Objective:To determine the effectiveness of exercise therapy on functional balance,physical performance,and quality of life among patients undergoing hemodialysis:a randomized controlled trial.Methods:This randomized controlled trial study was carried out on 68 patients with chronic kidney disease undergoing hemodialysis for at least six months and had a medically stable condition who were randomly divided into training(n=32)exercise therapy and(n=31)control,groups.The training group participated in 8-week(3 sessions per week)resistance exercise therapy in three sets of 10 repetitions of knee extension,hip flexion,and hip abduction with the use of an elastic band under the supervision of a training physiotherapist and researcher during the first hour of the three routine hemodialysis treatment session per week.But the control group did not experience any intervention.To analyze the data,two-way analysis of variance and Bonferroni statistical tests were used at the significant level of(P=0.05).Results:6 Minute-Walk Test(6MWT)(0.013),and in the Physical Activity Scale for the Elderly(PASE)(0.014),and Short Survey Form 36(SF-36)questionnaires and health-related quality of life(HRQOL)(0.001)had significant improvements in the training group in comparison to the control group from pre to post-test,also physical performance(0.001)was improving as compared with control group(0.89)at(P=0.05).Conclusion:Resistance exercise therapy interventions for eight weeks effectively improve the physical function and performance,activity levels,and health-related quality of life of patients with chronic kidney disease and undergoing regular hemodialysis compared with a control group.
文摘Performance of quality monitor models in spot welding determines the monitor precision directly, so it’s crucial to evaluate it. Previously, mean square error (MSE) is often used to evaluate performances of models, but it can only show the total errors of finite specimens of models, and cannot show whether the quality information inferred from models are accurate and reliable enough or not. For this reason, by means of measure error theory, a new way to evaluate the performances of models according to the error distributions is developed as follows: Only if correct and precise enough the error distribution of model is, the quality information inferred from model is accurate and reliable.
