To analyze the influence of the transit accessibility of stops on the travel mode choices of suburban residents,the number of the lines passing by the stops within an accessible range of the resident origin and destin...To analyze the influence of the transit accessibility of stops on the travel mode choices of suburban residents,the number of the lines passing by the stops within an accessible range of the resident origin and destination(OD)points and the average waiting time are used as the indexes of the transit accessibility of stops.Due to the correlation between travel time and accessible range,the transit accessibility of stops is contrasted as piecewise variables constrained by travel time.Taking the Jimei District of Xiamen,China,as an example,a binary logistic regression model of the suburban travel mode choice is constructed.The results show that it is necessary to construct transit accessibility of stops as piecewise variables.With a higher transit accessibility of stops,more residents will choose public transport.The choice of the travel mode is correlated with family attributes and personal characteristics.Morning and evening peak hours and travel distance have little effect on the choice of travel mode.Compared with the travel in urban areas,residents often chose public transport for travel within the suburbs.This research provides a basis for encouraging public transportation priority policies and decision making for transport planners in the suburbs.展开更多
Currently,it is difficult to extract the depth feature of the frontal emergency stops dangerous activity signal,which leads to a decline in the accuracy and efficiency of the frontal emergency stops the dangerous acti...Currently,it is difficult to extract the depth feature of the frontal emergency stops dangerous activity signal,which leads to a decline in the accuracy and efficiency of the frontal emergency stops the dangerous activ-ity.Therefore,a recognition for frontal emergency stops dangerous activity algorithm based on Nano Internet of Things Sensor(NIoTS)and transfer learning is proposed.First,the NIoTS is installed in the athlete’s leg muscles to collect activity signals.Second,the noise component in the activity signal is removed using the de-noising method based on mathematical morphology.Finally,the depth feature of the activity signal is extracted through the deep transfer learning model,and the Euclidean distance between the extracted feature and the depth feature of the frontal emergency stops dangerous activity signal is compared.If the European distance is small,it can be judged as the frontal emergency stops dangerous activity,and the frontal emergency stops dangerous activity recognition is realized.The results show that the average time delay of activity signal acquisition of the algorithm is low,the signal-to-noise ratio of the action signal is high,and the activity signal mean square error is low.The variance of the frontal emergency stops dangerous activity recognition does not exceed 0.5.The difference between the appearance time of the dangerous activity and the recognition time of the algorithm is 0.15 s,it can accurately and quickly recognize the frontal emergency stops the dangerous activity.展开更多
Languages differ in their phoneme inventories. Some phonemes exist in more than one language but others exist in relatively few languages. More specifically, English Language has some sounds that Arabic does not have ...Languages differ in their phoneme inventories. Some phonemes exist in more than one language but others exist in relatively few languages. More specifically, English Language has some sounds that Arabic does not have and vice versa. This paper focuses on the perception of the English bilabial stops/b/and/p/in contrast to the perception of the English alveolar stops/t/and/d/by some Saudi linguists who have been speaking English for more than six years and who are currently in an English speaking country, Australia. This phenomenon of perception of the English bilabial stops/b/and/p/will be tested mainly by virtue of minimal pairs and other words that may better help to investigate this perception. The paper uses some minimal pairs in which the bilabial and alveolar stops occur initially and finally. Also, it uses some verbs that end with the suffix/-ed/, but this/-ed/suffix is pronounced [t] or [d] when preceded by /p/ or /b/ respectively. Notice that [t] and [d] are allophones of the English past tense morpheme/-ed/（for example, Fromkin, Rodman, ＆ Hyams, 2007）. The pronunciation of the suffix as It] and [d] works as a clue for the subjects to know the preceding bilabial sound.展开更多
To determine how bus stop design influences mixed traffic operation near Chinese bus stops,a new theoretical method was developed by using additive-conflict-flows procedure.The procedure was extended from homogeneous ...To determine how bus stop design influences mixed traffic operation near Chinese bus stops,a new theoretical method was developed by using additive-conflict-flows procedure.The procedure was extended from homogeneous traffic flow to mixed traffic flow.Based on the procedure and queuing theory,car capacity and speed models were proposed for three types of bus stops including curbside,bus bay and bicycle detour.The effects of various combinations of bus stop type,traffic volume,bus dwell time,and berth number on traffic operations were investigated.The results indicate that traffic volume,bus dwell time and berth number have negative effects on traffic operations for any type of bus stops.For different types of bus stops,at car volumes above approximately 200 vehicles per hour,the bus bay and bicycle detour designs provide more benefits than the curbside design.As traffic volume increases,the benefit firstly increases in uncongested conditions and then decreases in congested conditions.It reaches the maximum at car volumes nearly 1 100 vehicles per hour.The results can be used to aid in the selection of a preferred bus stop design for a given traffic volume in developing countries.展开更多
Signal timings at signalized intersections are frequently optimized by considering com monlyusedvehicle delay models.It is generally believed that reducing the average number of stops can also decrease the average veh...Signal timings at signalized intersections are frequently optimized by considering com monlyusedvehicle delay models.It is generally believed that reducing the average number of stops can also decrease the average vehicle delay.Therefore,the aim of this research is to address the question:“Can similar performance outcomes be achieved through the Minimization of Average Vehicle Delay(MAVD)and the Minimization of Average Number of Stops(MANS)?”The first phase of the study entails the creation of two distinct signal timing optimization models based on the Akcelik average vehicle delay and average number of stops models.Subsequently,scripts were developed in MATLAB to identify the optimal signal timings for both approaches utilizing the Differential Evolution Algorithm.In the third phase,30 traffic scenarios were generated,each varying in overall traffic vol umes at the intersection.Subsequently,the signal timings derived from the MAVD and MANSapproaches were applied independently to these scenarios,and performance indica tors(average vehicle delay and average number of stops)were compared.The results reveal that the utilization of MANS-based signal timings instead of MAVD may lead to an increase in average vehicle delays of up to 113.55%.Additionally,it is demonstrated that when MAVD-based signal timings are applied instead of MANS,the average number of stops can increase by up to 16.28%.Finally,it is concluded that as the overall traffic volume at the intersection increases,these growth rates tend to decrease.展开更多
When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling o...When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling of driving.Ifs fun!展开更多
This paper aims to answer how to use traffic information to design energy management strategies for fuel cell buses in a networked environment.For the buses entering the bus stops scenario,this paper proposes a hierar...This paper aims to answer how to use traffic information to design energy management strategies for fuel cell buses in a networked environment.For the buses entering the bus stops scenario,this paper proposes a hierarchical energy management strategy for fuel cell buses,which considers the traffic information near the bus stops.In the upper-level trajectory planning stage,the optimal SOC trajectory under various historical traffic conditions is solved through dynamic planning.The traffic information and the best SOC trajectory are mapped through BiLSTM,which can achieve fast,real-time long-term SOC reference.In the lower-level real-time predictive energy management strategy,the optimal SOC is used as the state reference to guide the predictive energy management of fuel cell buses when entering the bus stops.Simulation results show that compared with the strategy without SOC trajectory reference,the life cost of the proposed strategy is reduced by 13.8%,and the total cost is reduced by 3.61%.The SOC of the proposed strategy is closer to the DP optimal solution.展开更多
This paper investigates the start-up and shutdown phases of a five-bladed closed-impeller centrifugal pump through experimental analysis,capturing the temporal evolution of its hydraulic performances.The study also pr...This paper investigates the start-up and shutdown phases of a five-bladed closed-impeller centrifugal pump through experimental analysis,capturing the temporal evolution of its hydraulic performances.The study also predicts the transient characteristics of the pump under non-rated operating conditions to assess the accuracy of various machine learning methods in forecasting its instantaneous performance.Results indicate that the pump’s transient behavior in power-frequency mode markedly differs from that in frequency-conversion mode.Specifically,the power-frequency mode achieves steady-state values faster and exhibits smaller fluctuations before stabilization compared to the other mode.During the start-up phase,as the steady-state flow rate increases,inlet and outlet pressures and head also rise,while torque and shaft power decrease,with rotational speed remaining largely unchanged.Conversely,during the shutdown phase,no significant changes were observed in torque,shaft power,or rotational speed.Six machine learning models,including Gaussian Process Regression(GPR),Decision Tree Regression(DTR),and Deep Learning Networks(DLN),demonstrated high accuracy in predicting the hydraulic performance of the centrifugal pump during the start-up and shutdown phases in both power-frequency and frequency-conversion conditions.The findings provide a theoretical foundation for improved prediction of pump hydraulic performance.For instance,when predicting head and flow rate during power-frequency start-up,GPR achieved absolute and relative errors of 0.54 m(7.84%)and 0.21 m3/h(13.57%),respectively,while the Feedforward Neural Network(FNN)reported errors of 0.98 m(8.24%)and 0.10 m3/h(16.71%).By contrast,the Support Vector Machine Regression(SVMR)and Generalized Additive Model(GAM)generally yielded less satisfactory prediction accuracy compared to the other methods.展开更多
We investigate the influence of gold doping on the transport range of a relativistic electron beam in high-density deuterium–tritium(DT)fuel,which could be encountered in the double-cone ignition laser fusion.We deve...We investigate the influence of gold doping on the transport range of a relativistic electron beam in high-density deuterium–tritium(DT)fuel,which could be encountered in the double-cone ignition laser fusion.We develop the stopping power model to include gold doping and then analyze the influence of Coulomb collision and bremsstrahlung on the electron transport range with different gold doping ratios,consistent with the Geant4 simulations.When the gold doping ratio increases from 0.5%to 30%,the transport range of a 10 Me V electron beam is decreased by 9.6%and 18.5%via the bremsstrahlung.For the 1 Me V beam,the decrease of the range becomes 0.7%and 1.0%.We also investigate the transverse broadening of the electron beam and radiated photon energy reabsorption in a spherical target.When the gold doping ratio is 2%and the beam energy is increased from 1 Me V to 5 Me V,the bremsstrahlung photons cover 2.6%to 10.3%of the total beam energy.Meanwhile,the reabsorbed photon energy is reduced from 31.6%to 8.9%.展开更多
To address the sensitive and uncertain limitations of single-energy computed tomography(CT)calibration methods in computing proton stopping power ratio during treatment planning,different methods have been proposed us...To address the sensitive and uncertain limitations of single-energy computed tomography(CT)calibration methods in computing proton stopping power ratio during treatment planning,different methods have been proposed using a dual energy CT approach.This paper reviews the most recent dual-energy CT approaches for computing proton stopping power ratio.These include image domain and projection domain methods.The advantages and uncertainties of these methods are analyzed based on existing studies.This paper highlights recent advances in dual energy CT,discussing their implementation,advantages,limitations,and potential for clinical adoption.展开更多
Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-dope...Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-doped double perovskites are common,research on their thermoluminescence(TL)properties is less extensive.This study synthesized a series of Y_(2-x)Sm_(x)MgTiO_(6)(0≤x≤0.1)samples using a high-temperature solid-state method.X-ray diffraction(XRD)analysis confirmed a monoclinic crystal structure(space group P2_(1)∕n),with Sm^(3+)ions substituting for Y^(3+)ions in Y_(2)MgTiO_(6).The PL results indicated that the optimal doping concentration was Y_(1.95)Sm_(0.05)MgTiO_(6),exhibiting emission peaks at 568,605,652,and 715 nm under 409 nm blue light excitation.The TL measurements for different doping concentrations showed that the Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors exhibited the strongest TL signals.The TL peaks observed at 530 and 610 K correspond to defects in the matrix and Sm^(3+)dopants,respectively.The T_(m)-T_(stop)analysis revealed that the TL curve of Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors was a superposition of seven peaks.Computerized glow curve deconvolution(CGCD)was performed on the TL of the sample according to the results of three-dimensional thermoluminescence spectra(3D-TL)and T_(m)-T_(stop),and the trap depths in the sample were estimated to range from 0.69 to 1.49 eV.Additionally,the lifetimes of each overlapping peak were calculated using the fitting parameters.Furthermore,the dose-response test showed that the saturation dose of the sample was high(9956 Gy).Therefore,this material can serve as a thermoluminescent dosimeter for high-dose measurements.The saturation dose for the lowest-temperature overlapping peak was 102 Gy,which correlated with its specific energy-level lifetime,whereas the other overlapping peaks also exhibited favorable linear relationships.展开更多
Beijing has been making preparations to present a dope-free Olympics next yearThe China Anti-Doping Agency,set up to replace the 17-year-old China Doping Control Center,was offi- cially unveiled in Beijing on November...Beijing has been making preparations to present a dope-free Olympics next yearThe China Anti-Doping Agency,set up to replace the 17-year-old China Doping Control Center,was offi- cially unveiled in Beijing on November 12.Between July 27 next year,when the Olympic Village is opened to athletes,and August 24,the last day of the Olympic Games,a total of 4,500 doping tests will be conducted in the build- ing.This number is 25 percent higher than that of the Athens Olympic Games in 2004 and 63 percent higher than at the Sydney Olympics in 2000.展开更多
Amid the fuss and jitters over a $700-billion emergency bailout package going through the U.S. Congress, meant to rescue America’s ailing economy, and panic and plunges across stock exchanges world-
To determinate car capacity at bus stops with mixed traffic, a new theoretical approach was developed on the basis of additive-conflict-flows procedure. The procedure was extended from homogeneous traffic flow to mixe...To determinate car capacity at bus stops with mixed traffic, a new theoretical approach was developed on the basis of additive-conflict-flows procedure. The procedure was extended from homogeneous traffic flow to mixed traffic flow. The conflicts among cars, buses and bicycles near the stop can be described by the extended procedure. The procedure can be understood more easily than the theory of gap acceptance. Car capacity near the stop is the function of both bus stream and bicycle stream. The proposed model can also analyze the cases of pedestrian effects and limited priority of bicyclists. Numerical results show that the car capacity decreases with the increasing flow rates of other streams. In addition, pedestrian effects and bicyclist's limited priority have negative effects on car capacity near bus stops with mixed traffic flow.展开更多
Waiting time at transit stops is found to be an influential policy variable for a passenger’s decision on whether to undertake a given transit service. With regard to policy framework for improvement of operational s...Waiting time at transit stops is found to be an influential policy variable for a passenger’s decision on whether to undertake a given transit service. With regard to policy framework for improvement of operational service headway of a transit service and thereby its waiting time, the necessity to have knowledge on its critical value becomes inevitable. The critical value of waiting time for passengers waiting at transit stops is that duration beyond which passengers are found to be no more interested to wait for a that transit service. The paper demonstrates an approach for estimating the critical value of waiting time at urban transit stops with reference to public transport services such as city bus and shared-auto operational in Bhubaneswar, India. The critical value of waiting time is estimated from the point on cumulative distribution curve of waiting time frequency distribution, at which the maximum rate of change of the slope of curve occurs. The work assumes two positively skewed distributions such as gamma and log-normal for observed distributional pattern of waiting time. The work identifies that gamma distribution is comparatively fitting the observed data better than log-normal distribution. The study reveals that the critical value of waiting time for city bus passengers is about twice than that of shared auto passengers.Though, the study presents new information on critical values of waiting time with reference to an urban area of a developing country, it also demonstrates an experience on application of probability distribution functions for understanding distributional pattern of waiting time.展开更多
This study develops a methodology to consohdate transit stops. It develops a mathematical model and a program which takes stop consolidation decision（s） according to users gener- alized travel time savings and desir...This study develops a methodology to consohdate transit stops. It develops a mathematical model and a program which takes stop consolidation decision（s） according to users gener- alized travel time savings and desired accessibility. The model iterates until the users generalized travel time savings are maximized. The study tests this mathematical model in different hypothetical scenarios. Six factors （distance between stops, passenger activity, average cruising speed, maximum walking distance, service frequency, and percentage of decreased passengers） with multiple levels were set to build the scenarios. Three responses {percentage of consolidated stops, percentages of travel time and operating time savings） were observed. The findings showed that the distance between the stops the passenger ac- tivity, and the probable demand change （or the percentage of decreased passengers） are the most influential factors. The frequency of service was found to be influential as well. The average cruising speed has very little influence on the response variables. Finally, the model is tested on two routes （route 900 and 930） ofAl Ain City public bus service. It shows that 22 and 32 out of 98 and 126 stops can be consolidated in route 900 and 930 respectively. This can save considerable amounts of users travel and operating times. In monetary values, the savings are about $329,827 and $491,094 per year for routes 900 and 930, respectively.展开更多
On July 29<sup>th</sup>,2004,Lanzhou Aluminum Co.Ltd.stopped its 28 sets of 60 KA self-bakingpots that had been applied for 38 years.This isthe end of the application of self-baking potsand equipment that ...On July 29<sup>th</sup>,2004,Lanzhou Aluminum Co.Ltd.stopped its 28 sets of 60 KA self-bakingpots that had been applied for 38 years.This isthe end of the application of self-baking potsand equipment that had played an importantrole in the development of Lanzhou AluminumCo.Ltd.Since the Company （the former Lan-zhou Aluminum Plant） was put into reproduc-tion in 1966,the Soderberg technology hadbeen applied for producing primary aluminum.This type of backward technology had not beenfully stopped since August 2002 when the100,000-ton pre-baked pots with 200 KAcommenced production.Since February展开更多
基金The National Natural Science Foundation of China(No.52078224)Promotion Program for Young and Middle-Aged Teachers in Science and Technology Research at Huaqiao University(No.600005-Z17X0170).
文摘To analyze the influence of the transit accessibility of stops on the travel mode choices of suburban residents,the number of the lines passing by the stops within an accessible range of the resident origin and destination(OD)points and the average waiting time are used as the indexes of the transit accessibility of stops.Due to the correlation between travel time and accessible range,the transit accessibility of stops is contrasted as piecewise variables constrained by travel time.Taking the Jimei District of Xiamen,China,as an example,a binary logistic regression model of the suburban travel mode choice is constructed.The results show that it is necessary to construct transit accessibility of stops as piecewise variables.With a higher transit accessibility of stops,more residents will choose public transport.The choice of the travel mode is correlated with family attributes and personal characteristics.Morning and evening peak hours and travel distance have little effect on the choice of travel mode.Compared with the travel in urban areas,residents often chose public transport for travel within the suburbs.This research provides a basis for encouraging public transportation priority policies and decision making for transport planners in the suburbs.
文摘Currently,it is difficult to extract the depth feature of the frontal emergency stops dangerous activity signal,which leads to a decline in the accuracy and efficiency of the frontal emergency stops the dangerous activ-ity.Therefore,a recognition for frontal emergency stops dangerous activity algorithm based on Nano Internet of Things Sensor(NIoTS)and transfer learning is proposed.First,the NIoTS is installed in the athlete’s leg muscles to collect activity signals.Second,the noise component in the activity signal is removed using the de-noising method based on mathematical morphology.Finally,the depth feature of the activity signal is extracted through the deep transfer learning model,and the Euclidean distance between the extracted feature and the depth feature of the frontal emergency stops dangerous activity signal is compared.If the European distance is small,it can be judged as the frontal emergency stops dangerous activity,and the frontal emergency stops dangerous activity recognition is realized.The results show that the average time delay of activity signal acquisition of the algorithm is low,the signal-to-noise ratio of the action signal is high,and the activity signal mean square error is low.The variance of the frontal emergency stops dangerous activity recognition does not exceed 0.5.The difference between the appearance time of the dangerous activity and the recognition time of the algorithm is 0.15 s,it can accurately and quickly recognize the frontal emergency stops the dangerous activity.
文摘Languages differ in their phoneme inventories. Some phonemes exist in more than one language but others exist in relatively few languages. More specifically, English Language has some sounds that Arabic does not have and vice versa. This paper focuses on the perception of the English bilabial stops/b/and/p/in contrast to the perception of the English alveolar stops/t/and/d/by some Saudi linguists who have been speaking English for more than six years and who are currently in an English speaking country, Australia. This phenomenon of perception of the English bilabial stops/b/and/p/will be tested mainly by virtue of minimal pairs and other words that may better help to investigate this perception. The paper uses some minimal pairs in which the bilabial and alveolar stops occur initially and finally. Also, it uses some verbs that end with the suffix/-ed/, but this/-ed/suffix is pronounced [t] or [d] when preceded by /p/ or /b/ respectively. Notice that [t] and [d] are allophones of the English past tense morpheme/-ed/（for example, Fromkin, Rodman, ＆ Hyams, 2007）. The pronunciation of the suffix as It] and [d] works as a clue for the subjects to know the preceding bilabial sound.
基金Project(2012CB725400) supported by the National Basic Research Program of ChinaProjects(70901005, 71071016, 71131001) supported by the National Natural Science Foundation of ChinaProject(2011JBM055) supported by the Fundamental Research Funds for the Central Universities of China
文摘To determine how bus stop design influences mixed traffic operation near Chinese bus stops,a new theoretical method was developed by using additive-conflict-flows procedure.The procedure was extended from homogeneous traffic flow to mixed traffic flow.Based on the procedure and queuing theory,car capacity and speed models were proposed for three types of bus stops including curbside,bus bay and bicycle detour.The effects of various combinations of bus stop type,traffic volume,bus dwell time,and berth number on traffic operations were investigated.The results indicate that traffic volume,bus dwell time and berth number have negative effects on traffic operations for any type of bus stops.For different types of bus stops,at car volumes above approximately 200 vehicles per hour,the bus bay and bicycle detour designs provide more benefits than the curbside design.As traffic volume increases,the benefit firstly increases in uncongested conditions and then decreases in congested conditions.It reaches the maximum at car volumes nearly 1 100 vehicles per hour.The results can be used to aid in the selection of a preferred bus stop design for a given traffic volume in developing countries.
文摘Signal timings at signalized intersections are frequently optimized by considering com monlyusedvehicle delay models.It is generally believed that reducing the average number of stops can also decrease the average vehicle delay.Therefore,the aim of this research is to address the question:“Can similar performance outcomes be achieved through the Minimization of Average Vehicle Delay(MAVD)and the Minimization of Average Number of Stops(MANS)?”The first phase of the study entails the creation of two distinct signal timing optimization models based on the Akcelik average vehicle delay and average number of stops models.Subsequently,scripts were developed in MATLAB to identify the optimal signal timings for both approaches utilizing the Differential Evolution Algorithm.In the third phase,30 traffic scenarios were generated,each varying in overall traffic vol umes at the intersection.Subsequently,the signal timings derived from the MAVD and MANSapproaches were applied independently to these scenarios,and performance indica tors(average vehicle delay and average number of stops)were compared.The results reveal that the utilization of MANS-based signal timings instead of MAVD may lead to an increase in average vehicle delays of up to 113.55%.Additionally,it is demonstrated that when MAVD-based signal timings are applied instead of MANS,the average number of stops can increase by up to 16.28%.Finally,it is concluded that as the overall traffic volume at the intersection increases,these growth rates tend to decrease.
文摘When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling of driving.Ifs fun!
基金supported by the National Natural Science Foundation of China(Grand No.52202484)the Hebei Natural Science Foundation(Grand No.F2021203118)+1 种基金the Beijing Natural Science Foundation(Grand No.J210007)the Science and Technology Project of Hebei Education Department(Grand No.QN2022093).
文摘This paper aims to answer how to use traffic information to design energy management strategies for fuel cell buses in a networked environment.For the buses entering the bus stops scenario,this paper proposes a hierarchical energy management strategy for fuel cell buses,which considers the traffic information near the bus stops.In the upper-level trajectory planning stage,the optimal SOC trajectory under various historical traffic conditions is solved through dynamic planning.The traffic information and the best SOC trajectory are mapped through BiLSTM,which can achieve fast,real-time long-term SOC reference.In the lower-level real-time predictive energy management strategy,the optimal SOC is used as the state reference to guide the predictive energy management of fuel cell buses when entering the bus stops.Simulation results show that compared with the strategy without SOC trajectory reference,the life cost of the proposed strategy is reduced by 13.8%,and the total cost is reduced by 3.61%.The SOC of the proposed strategy is closer to the DP optimal solution.
基金financially supported by Science and Technology Project of Quzhou(Grant Nos.2023K256,2023NC08)Research Grants Program of Department of Education of Zhejiang Province(No.Y202455709)+1 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LZY21E050001)University-Enterprise Cooperation Program for Visiting Engineers in Higher Education Institutions in Zhejiang Province(No.FG2020215).
文摘This paper investigates the start-up and shutdown phases of a five-bladed closed-impeller centrifugal pump through experimental analysis,capturing the temporal evolution of its hydraulic performances.The study also predicts the transient characteristics of the pump under non-rated operating conditions to assess the accuracy of various machine learning methods in forecasting its instantaneous performance.Results indicate that the pump’s transient behavior in power-frequency mode markedly differs from that in frequency-conversion mode.Specifically,the power-frequency mode achieves steady-state values faster and exhibits smaller fluctuations before stabilization compared to the other mode.During the start-up phase,as the steady-state flow rate increases,inlet and outlet pressures and head also rise,while torque and shaft power decrease,with rotational speed remaining largely unchanged.Conversely,during the shutdown phase,no significant changes were observed in torque,shaft power,or rotational speed.Six machine learning models,including Gaussian Process Regression(GPR),Decision Tree Regression(DTR),and Deep Learning Networks(DLN),demonstrated high accuracy in predicting the hydraulic performance of the centrifugal pump during the start-up and shutdown phases in both power-frequency and frequency-conversion conditions.The findings provide a theoretical foundation for improved prediction of pump hydraulic performance.For instance,when predicting head and flow rate during power-frequency start-up,GPR achieved absolute and relative errors of 0.54 m(7.84%)and 0.21 m3/h(13.57%),respectively,while the Feedforward Neural Network(FNN)reported errors of 0.98 m(8.24%)and 0.10 m3/h(16.71%).By contrast,the Support Vector Machine Regression(SVMR)and Generalized Additive Model(GAM)generally yielded less satisfactory prediction accuracy compared to the other methods.
基金Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA25050300 and XDA25010100)the National Key R&D Program of China(Grant No.2018YFA0404801)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant No.20XNLG01)。
文摘We investigate the influence of gold doping on the transport range of a relativistic electron beam in high-density deuterium–tritium(DT)fuel,which could be encountered in the double-cone ignition laser fusion.We develop the stopping power model to include gold doping and then analyze the influence of Coulomb collision and bremsstrahlung on the electron transport range with different gold doping ratios,consistent with the Geant4 simulations.When the gold doping ratio increases from 0.5%to 30%,the transport range of a 10 Me V electron beam is decreased by 9.6%and 18.5%via the bremsstrahlung.For the 1 Me V beam,the decrease of the range becomes 0.7%and 1.0%.We also investigate the transverse broadening of the electron beam and radiated photon energy reabsorption in a spherical target.When the gold doping ratio is 2%and the beam energy is increased from 1 Me V to 5 Me V,the bremsstrahlung photons cover 2.6%to 10.3%of the total beam energy.Meanwhile,the reabsorbed photon energy is reduced from 31.6%to 8.9%.
文摘To address the sensitive and uncertain limitations of single-energy computed tomography(CT)calibration methods in computing proton stopping power ratio during treatment planning,different methods have been proposed using a dual energy CT approach.This paper reviews the most recent dual-energy CT approaches for computing proton stopping power ratio.These include image domain and projection domain methods.The advantages and uncertainties of these methods are analyzed based on existing studies.This paper highlights recent advances in dual energy CT,discussing their implementation,advantages,limitations,and potential for clinical adoption.
基金supported by the Zhanjiang Science and Technology Plan Project(No.2022A05022)Science and Technology Development Special Project of Zhanjiang(No.2023A21616)Research Project of Guangdong Ocean University(No.060302112102).
文摘Double perovskite matrix materials have recently attracted considerable interest due to their structural flexibility,ease of doping,and excellent thermal stability.While photoluminescence(PL)studies of rare-earth-doped double perovskites are common,research on their thermoluminescence(TL)properties is less extensive.This study synthesized a series of Y_(2-x)Sm_(x)MgTiO_(6)(0≤x≤0.1)samples using a high-temperature solid-state method.X-ray diffraction(XRD)analysis confirmed a monoclinic crystal structure(space group P2_(1)∕n),with Sm^(3+)ions substituting for Y^(3+)ions in Y_(2)MgTiO_(6).The PL results indicated that the optimal doping concentration was Y_(1.95)Sm_(0.05)MgTiO_(6),exhibiting emission peaks at 568,605,652,and 715 nm under 409 nm blue light excitation.The TL measurements for different doping concentrations showed that the Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors exhibited the strongest TL signals.The TL peaks observed at 530 and 610 K correspond to defects in the matrix and Sm^(3+)dopants,respectively.The T_(m)-T_(stop)analysis revealed that the TL curve of Y_(1.98)Sm_(0.02)MgTiO_(6)phosphors was a superposition of seven peaks.Computerized glow curve deconvolution(CGCD)was performed on the TL of the sample according to the results of three-dimensional thermoluminescence spectra(3D-TL)and T_(m)-T_(stop),and the trap depths in the sample were estimated to range from 0.69 to 1.49 eV.Additionally,the lifetimes of each overlapping peak were calculated using the fitting parameters.Furthermore,the dose-response test showed that the saturation dose of the sample was high(9956 Gy).Therefore,this material can serve as a thermoluminescent dosimeter for high-dose measurements.The saturation dose for the lowest-temperature overlapping peak was 102 Gy,which correlated with its specific energy-level lifetime,whereas the other overlapping peaks also exhibited favorable linear relationships.
文摘Beijing has been making preparations to present a dope-free Olympics next yearThe China Anti-Doping Agency,set up to replace the 17-year-old China Doping Control Center,was offi- cially unveiled in Beijing on November 12.Between July 27 next year,when the Olympic Village is opened to athletes,and August 24,the last day of the Olympic Games,a total of 4,500 doping tests will be conducted in the build- ing.This number is 25 percent higher than that of the Athens Olympic Games in 2004 and 63 percent higher than at the Sydney Olympics in 2000.
文摘Amid the fuss and jitters over a $700-billion emergency bailout package going through the U.S. Congress, meant to rescue America’s ailing economy, and panic and plunges across stock exchanges world-
基金supported by the National Basic Research Program of China (Grant No. 2006CB705503)National Natural Science Foundation of China (Grant Nos. 70901005, 70631001, 71071016)Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090009120015)
文摘To determinate car capacity at bus stops with mixed traffic, a new theoretical approach was developed on the basis of additive-conflict-flows procedure. The procedure was extended from homogeneous traffic flow to mixed traffic flow. The conflicts among cars, buses and bicycles near the stop can be described by the extended procedure. The procedure can be understood more easily than the theory of gap acceptance. Car capacity near the stop is the function of both bus stream and bicycle stream. The proposed model can also analyze the cases of pedestrian effects and limited priority of bicyclists. Numerical results show that the car capacity decreases with the increasing flow rates of other streams. In addition, pedestrian effects and bicyclist's limited priority have negative effects on car capacity near bus stops with mixed traffic flow.
基金project grant under the IMPacting Research, INnovation and Technology (IMPRINT)-India initiative (Project code #7094).The grant is jointly supported by the Ministry of Human Resource Development (MHRD), Govt.of India and the Ministry of Housing and Urban Affairs (MoHUA), Govt.of India。
文摘Waiting time at transit stops is found to be an influential policy variable for a passenger’s decision on whether to undertake a given transit service. With regard to policy framework for improvement of operational service headway of a transit service and thereby its waiting time, the necessity to have knowledge on its critical value becomes inevitable. The critical value of waiting time for passengers waiting at transit stops is that duration beyond which passengers are found to be no more interested to wait for a that transit service. The paper demonstrates an approach for estimating the critical value of waiting time at urban transit stops with reference to public transport services such as city bus and shared-auto operational in Bhubaneswar, India. The critical value of waiting time is estimated from the point on cumulative distribution curve of waiting time frequency distribution, at which the maximum rate of change of the slope of curve occurs. The work assumes two positively skewed distributions such as gamma and log-normal for observed distributional pattern of waiting time. The work identifies that gamma distribution is comparatively fitting the observed data better than log-normal distribution. The study reveals that the critical value of waiting time for city bus passengers is about twice than that of shared auto passengers.Though, the study presents new information on critical values of waiting time with reference to an urban area of a developing country, it also demonstrates an experience on application of probability distribution functions for understanding distributional pattern of waiting time.
基金part of an MSc study thesis sponsored by the Roadway,Transportation and Traffic Safety Research Center at the UAE University
文摘This study develops a methodology to consohdate transit stops. It develops a mathematical model and a program which takes stop consolidation decision（s） according to users gener- alized travel time savings and desired accessibility. The model iterates until the users generalized travel time savings are maximized. The study tests this mathematical model in different hypothetical scenarios. Six factors （distance between stops, passenger activity, average cruising speed, maximum walking distance, service frequency, and percentage of decreased passengers） with multiple levels were set to build the scenarios. Three responses {percentage of consolidated stops, percentages of travel time and operating time savings） were observed. The findings showed that the distance between the stops the passenger ac- tivity, and the probable demand change （or the percentage of decreased passengers） are the most influential factors. The frequency of service was found to be influential as well. The average cruising speed has very little influence on the response variables. Finally, the model is tested on two routes （route 900 and 930） ofAl Ain City public bus service. It shows that 22 and 32 out of 98 and 126 stops can be consolidated in route 900 and 930 respectively. This can save considerable amounts of users travel and operating times. In monetary values, the savings are about $329,827 and $491,094 per year for routes 900 and 930, respectively.
文摘On July 29<sup>th</sup>,2004,Lanzhou Aluminum Co.Ltd.stopped its 28 sets of 60 KA self-bakingpots that had been applied for 38 years.This isthe end of the application of self-baking potsand equipment that had played an importantrole in the development of Lanzhou AluminumCo.Ltd.Since the Company （the former Lan-zhou Aluminum Plant） was put into reproduc-tion in 1966,the Soderberg technology hadbeen applied for producing primary aluminum.This type of backward technology had not beenfully stopped since August 2002 when the100,000-ton pre-baked pots with 200 KAcommenced production.Since February
