Mobile Crowd Sensing(MCS)is an emerging paradigm that leverages sensor-equipped smart devices to collect data.The introduction of MCS also poses some challenges such as providing highquality data for upper layer MCS a...Mobile Crowd Sensing(MCS)is an emerging paradigm that leverages sensor-equipped smart devices to collect data.The introduction of MCS also poses some challenges such as providing highquality data for upper layer MCS applications,which requires adequate participants.However,recruiting enough participants to provide the sensing data for free is hard for the MCS platform under a limited budget,which may lead to a low coverage ratio of sensing area.This paper proposes a novel method to choose participants uniformly distributed in a specific sensing area based on the mobility patterns of mobile users.The method consists of two steps:(1)A second-order Markov chain is used to predict the next positions of users,and select users whose next places are in the target sensing area to form a candidate pool.(2)The Average Entropy(DAE)is proposed to measure the distribution of participants.The participant maximizing the DAE value of a specific sensing area with different granular sub-areas is chosen to maximize the coverage ratio of the sensing area.Experimental results show that the proposed method can maximize the coverage ratio of a sensing area under different partition granularities.展开更多
Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of off...Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.展开更多
It is inevitable that Connected and Autonomous Vehicles (CAVs) will be a major focus of transportation and the automotive industry with increased use in future traffic system analysis. Numerous studies have focused on...It is inevitable that Connected and Autonomous Vehicles (CAVs) will be a major focus of transportation and the automotive industry with increased use in future traffic system analysis. Numerous studies have focused on the evaluation and potential development of CAVs technology;however, pedestrians and bicyclists, as two essential and important modes of the road users have seen little to no coverage. In response to the need for analyzing the impact of CAVs on non-motorized transportation, this paper develops a new model for the evaluation of the Level of Service (LOS) for pedestrians in a CAVs environment based on the Highway Capacity Manual (HCM). The HCM provides a methodology to assess the level of service for pedestrians and bicyclists on various types of intersections in urban areas. Five scenarios were created for simulation via VISSIM (a software) that corresponds to the different proportions of the CAVs and different signal systems in a typical traffic environment. Alternatively, the Surrogate Safety Assessment Model (SSAM) was selected for analyzing the safety performance of the five scenarios. Through computing and analyzing the results of simulation and SSAM, the latter portion of this paper focuses on the development of a new model for evaluating pedestrian LOS in urban areas which are based upon HCM standards which are suitable for CAVs environments. The results of this study are intended to inform the future efforts of engineers and/or policymakers and to provide them with a tool to conduct a comparison of capacity and LOS related to the impact of CAVs on pedestrians during the process of a transportation system transition to CAVs.展开更多
Bicycling is an important way for college students and employees to get around campuses. With a rise in bicycling on campuses there comes a rise in bicycle collisions with pedestrians walking to and from classes and w...Bicycling is an important way for college students and employees to get around campuses. With a rise in bicycling on campuses there comes a rise in bicycle collisions with pedestrians walking to and from classes and work. The literature review showed many papers involving bicycle conflict modeling but on roads with motor vehicles. While some aspects of this research can be applied to non-motorized paths, there is a lack of research strictly focusing on only bicycles and pedestrians. This study aims to fill this knowledge gap by developing a model to identify locations on roads and paths (hotspots) on college campuses that are likely to have a bicycle collision and predict the likelihood of a serious bicycle crash on a non-motorized path based on the characteristics of the path. This study identifies those interactions between bicyclists and pedestrians on non-motorized paths on a suburban college campus in Newark, USA. Findings suggest that pedestrian density of a path is a major factor in the maximum speed bicyclists can achieve. The wider the path is, the higher the maximum speed is that a bicyclist can obtain. This is because a wider path width decreases the pedestrian density. The grade of the path has little effect on bicycle speeds. The results of the models were displayed on a GIS map that is visually appealing to a viewer. The paths were color coded based on their level of safety, so it is easy to observe problematic areas of the network. This technique can be applied to the entire campus network of non-motorized paths to study the whole system. This can then be used by planners and designers to identify areas that need upgrading and improve the overall safety of the non-motorized path system.展开更多
This paper introduces the solidworks design flow, design methods and design principles of desk lamp. And we use the ergonomics principle, analysis the function of each part of the lamp, and analyses the design of lamp...This paper introduces the solidworks design flow, design methods and design principles of desk lamp. And we use the ergonomics principle, analysis the function of each part of the lamp, and analyses the design of lamp components, to meet user needs in the bedroom, do practical, human nature and convenient lamp. The application shows that the use of this software can make easier the realization of the design of the parts with complex shape, raise the design efficiency, optimize the product structure and save the cost.展开更多
Using the high spatiotemporal resolution(2 km-and-10 min)data from the Advanced Himawari Imager onboard the Himawari-8 satellite,this study documents the fine-scale characteristics of daytime cloud regimes(CRs)over co...Using the high spatiotemporal resolution(2 km-and-10 min)data from the Advanced Himawari Imager onboard the Himawari-8 satellite,this study documents the fine-scale characteristics of daytime cloud regimes(CRs)over coastal South China during the pre-summer rainy season(April–June).Six CRs(CR1–CR6)are identified based on the joint frequency distribution of cloud top brightness temperature and cloud optical thickness,namely,the optically thin-to-moderate cloud mixture,optically thin warm clouds with cirrus,optically thick warm clouds,weak convective cloud mixture,strong convective clouds,and extreme,deep convective clouds.The optically thick warm clouds are the major CR during April and May,with higher frequencies over land,especially along the urban agglomeration,rather than the offshore which may be an indicator of the higher aerosol concentrations being a contributing factor over the cities.The CRs with weak convective cloud mixtures and strong convective clouds appear more frequently over the land,while the two CRs with optically thinner clouds occur mainly offshore.Synoptic flow patterns(SPs)are objectively identified and examined focusing on those favoring the two major rainproducing CRs(CR5 and CR6)and the highly reflective CR with optically thick warm clouds(CR3).The two SPs favoring CR5 and CR6 are characterized by abundant moisture with low-level jets after monsoon onset,and a northwest highsoutheast low pattern with strong dynamic convergence along the coastline,respectively.The non-convective CR3 with high reflectance is related to a SP that features the western North Pacific subtropical high extending more westward,leading to a moderate moisture supply and a wide range of convective available potential energy,but also,large convective inhibition.展开更多
This work proposes a novel heating and cooling system,with incorporated thermoelectric module,that can achieve energy balance using a self-water supply heat exchange subsystem.The thermoelectric effect is used to achi...This work proposes a novel heating and cooling system,with incorporated thermoelectric module,that can achieve energy balance using a self-water supply heat exchange subsystem.The thermoelectric effect is used to achieve controlled and adjustable heating of the circulating water.Simulations were conducted to study the thermal performance of the system while it simultaneously produces hot and cold water,with different working conditions for the hot-and cold-side water outlets.The results show that the water temperature at the hot side outlet increases from 32℃to 75℃when the power increases from 4.5 to 50 W.Additionally,the use of thermoelectric modules to heat water and recover waste heat is 22%more efficient than ordinary electric water heating systems.展开更多
In addition to experiencing shortage in LTC workforce, some existing facilities are unable to provide quality service, since they were designed and built decades ago. Thus, the renovation of outdated LTC facilities is...In addition to experiencing shortage in LTC workforce, some existing facilities are unable to provide quality service, since they were designed and built decades ago. Thus, the renovation of outdated LTC facilities is currently an unavoidable issue. In this paper, some contemporary practices are presented related to renovating old LTC facilities to improve the quality of service. The most important concept is the person-centered design. Some other elements include the importance of natural lighting for residents, proper practices of flooring and picking doors, some details in home-like design, new guidelines for resident rooms’ design, and other miscellaneous issues. Furthermore, the latest Americans with Disabilities Act (ADA) compliance protocols are reviewed, and some crucial elements are discussed to ensure the renovations will make the facilities compliant with the current standards.展开更多
A sustained heavy rainfall event occurred over the Sichuan basin in southwest China during 10–18 August 2020,showing pronounced diurnal rainfall variations with nighttime peak and afternoon minimum values,except on t...A sustained heavy rainfall event occurred over the Sichuan basin in southwest China during 10–18 August 2020,showing pronounced diurnal rainfall variations with nighttime peak and afternoon minimum values,except on the first day.Results show that the westward extension of the anomalously strong western Pacific subtropical high was conducive to the maintenance of a southerly low-level jet(LLJ)in and to the southeast of the basin,which favored continuous water vapor transport and abnormally high precipitable water in the basin.The diurnal cycle of rainfall over the basin was closely related to the periodic oscillation of the LLJ in both wind speed and direction that was caused by the combination of inertial oscillation and terrain thermal forcing.The nocturnally enhanced rainfall was produced by moist convection mostly initiated during the evening hours over the southwest part of the basin where high convective available potential energy with moister near-surface moist air was present.The convective initiation took place as cold air from either previous precipitating clouds from the western Sichuan Plateau or a larger-scale northerly flow met a warm and humid current from the south.It was the slantwise lifting of the warm,moist airflow above the cold air,often facilitated by southwest vortices and quasi-geostrophic ascent,that released the convective instability and produced heavy rainfall.展开更多
Heavy ion beams with high linear energy transfer exhibit more beneifcial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of canc...Heavy ion beams with high linear energy transfer exhibit more beneifcial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irra-diation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy;subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunolfuorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was signiifcantly decreased, and there was ev-idence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our ifnd-ings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation.展开更多
Traditionally, the process used by public transportation entities to determine the acquisition strategy for new vehicle asset is based upon a broad range of criteria. Vehicle cost has been cited as one of the more cri...Traditionally, the process used by public transportation entities to determine the acquisition strategy for new vehicle asset is based upon a broad range of criteria. Vehicle cost has been cited as one of the more critical factors which decision makers consider. It is currently a common practice to consider other factors (life-cycle cost, fuel efficiency, vehicle reliability, environmental effects, etc.) that contribute to a more comprehensive approach. This study investigates the next generation of advancements in decision making tools in the area of the application of methods to quantify and manage uncertainty. In particular, the uncertainty comes from the public policy arena where future policy and regulations are not always based upon logical and predictable processes. The fleet decision making process in most governmental agencies is a very complex and interdependent activity. There are always competing forces and agendas within the view of the decision maker. Rarely is the decision maker a single person although, within the transit environment, there is often one person charged with the responsibility of fleet management. The focus of this research examines the decision making of the general transit agency community via the development of an expert systems prototype tool. A computer-based prototype system is developed which provide an expert knowledge-based recommendation, based upon variable user inputs. The results shown in this study show that a decision making tool for the management of transit system alternate fuel vehicle assets can be modeled and tested. The direct users of this research are the transit agency administrations. The results can be used by the management teams as a reliable input to inform their urban transit buses expansion decision making process.展开更多
The travel time data collection method is used to assist the congestion management. The use of traditional sensors (e.g. inductive loops, AVI sensors) or more recent Bluetooth sensors installed on major roads for coll...The travel time data collection method is used to assist the congestion management. The use of traditional sensors (e.g. inductive loops, AVI sensors) or more recent Bluetooth sensors installed on major roads for collecting data is not sufficient because of their limited coverage and expensive costs for installation and maintenance. Application of the Global Positioning Systems (GPS) in travel time and delay data collections is proven to be efficient in terms of accuracy, level of details for the data and required data collection of man-power. While data collection automation is improved by the GPS technique, human errors can easily find their way through the post-processing phase, and therefore data post-processing remains a challenge especially in case of big projects with high amount of data. This paper introduces a stand-alone post-processing tool called GPS Calculator, which provides an easy-to-use environment to carry out data post-processing. This is a Visual Basic application that processes the data files obtained in the field and integrates them into Geographic Information Systems (GIS) for analysis and representation. The results show that this tool obtains similar results to the currently used data post-processing method, reduces the post-processing effort, and also eliminates the need for the second person during the data collection.展开更多
Travel time and delay are among the most important measures for gauging a transportation system’s performance. To address the growing problem of congestion in the US, transportation planning legislation mandated the ...Travel time and delay are among the most important measures for gauging a transportation system’s performance. To address the growing problem of congestion in the US, transportation planning legislation mandated the monitoring and analysis of system performance and produced a renewed interest in travel time and delay studies. The use of traditional sensors installed on major roads (e.g. inductive loops) for collecting data is necessary but not sufficient because of their limited coverage and expensive costs for setting up and maintaining the required infrastructure. The GPS-based techniques employed by the University of Delaware have evolved into an automated system, which provides more realistic experience of a traffic flow throughout the road links. However, human error and the weaknesses of using GPS devices in urban settings still have the potential to create inaccuracies. By simultaneously collecting data using three different techniques, the accuracy of the GPS positioning data and the resulting travel time and delay values could be objectively compared for automation and statistically compared for accuracy. It was found that the new technique provided the greatest automation requiring minimal attention of the data collectors and automatically processing the data sets. The data samples were statistically analyzed by using a combination of parametric and nonparametric statistical tests. This analysis greatly favored the GeoStats GPS method over the rest methods.展开更多
Corn to sugar process has long faced the risks of high energy consumption and thin profits.However,it’s hard to upgrade or optimize the process based on mechanism unit operation models due to the high complexity of t...Corn to sugar process has long faced the risks of high energy consumption and thin profits.However,it’s hard to upgrade or optimize the process based on mechanism unit operation models due to the high complexity of the related processes.Big data technology provides a promising solution as its ability to turn huge amounts of data into insights for operational decisions.In this paper,a neural network-based production process modeling and variable importance analysis approach is proposed for corn to sugar processes,which contains data preprocessing,dimensionality reduction,multilayer perceptron/convolutional neural network/recurrent neural network based modeling and extended weights connection method.In the established model,dextrose equivalent value is selected as the output,and 654 sites from the DCS system are selected as the inputs.LASSO analysis is first applied to reduce the data dimension to 155,then the inputs are dimensionalized to 50 by means of genetic algorithm optimization.Ultimately,variable importance analysis is carried out by the extended weight connection method,and 20 of the most important sites are selected for each neural network.The results indicate that the multilayer perceptron and recurrent neural network models have a relative error of less than 0.1%,which have a better prediction result than other models,and the 20 most important sites selected have better explicable performance.The major contributions derived from this work are of significant aid in process simulation model with high accuracy and process optimization based on the selected most important sites to maintain high quality and stable production for corn to sugar processes.展开更多
This study examined the rainfall characteristics and related synoptic processes of two extreme rainfall events that affected North China during 29 July–1 August 2023(“23·7”rainstorm)and 3–5 August 1996(“96&#...This study examined the rainfall characteristics and related synoptic processes of two extreme rainfall events that affected North China during 29 July–1 August 2023(“23·7”rainstorm)and 3–5 August 1996(“96·8”rainstorm),respectively.A stable dual-typhoon circulation pattern was observed in both rainstorm events.The surviving vortex of a landed typhoon,slowly approaching the rainstorm region,was blocked by a high-pressure system as it moved northwestward.Meanwhile,the second typhoon over the western Pacific Ocean facilitated remote northward transport of moisture.The low-level jet between the surviving vortex and the western Pacific subtropical high relayed moist warm air from the area of the South China Sea and western Pacific into the rainstorm region.Although the circulation patterns are similar,the stratification conditions,driving factors,and moisture budget of the two rainstorms differed during the main period of rainfall.The“23·7”rainstorm was categorized as warm-sector rainfall,as a result of the lifting of warm moist air over the eastern foothills of Taihang Mountains.In comparison with the situation of the“96·8”rainstorm,the surviving vortex of the“23·7”rainstorm traveled further northeastward and directly impacted the occurrence and progression of the rainfall,leading to relative northward displacement of the rainfall center,while the stronger net inward moisture flux caused greater regional average rainfall.The“96·8”rainstorm was broadly analogous to precipitation of a cold front,and the rainfall center was observed in the convergence area of warm and cold air masses before the mountains;the surviving vortex did not exert direct impact on the rainfall;and the more unstable stratification led to stronger hourly rainfall.The results derived through comparison of the two rainstorms could serve as valuable scientific reference for operational forecasting of heavy rainfall under similar environmental conditions over North China.展开更多
North China experienced devastating rainfall from 29 July to 1 August 2023,which caused substantial flooding and damage.This study analyzed observations from surface rain gauges and S-band dual-polarization radars to ...North China experienced devastating rainfall from 29 July to 1 August 2023,which caused substantial flooding and damage.This study analyzed observations from surface rain gauges and S-band dual-polarization radars to reveal the following unique features of the precipitation evolution from the plain to the mountains during this event.(1) The total rainfall was found concentrated along the Taihang Mountains at elevations generally > 200 m,and its spatiotemporal evolution was closely associated with northward-moving low-level jets.(2) Storms propagated northwestward with southeasterly steering winds,producing continuous rainfall along the eastern slopes of the Taihang Mountains owing to mountain blocking,which resulted in the formation of local centers of precipitation maxima.However,most rainfall episodes with an extreme hourly rainfall rate(HRR),corresponding to large horizontal wind shear at low levels,actively occurred in the plain area to the east of the Taihang Mountains.(3) The western portion of the extreme heavy rain belt in the north was mainly caused by long-lasting cumulus–stratus mixed precipitation with HRR< 20 mm h~(-1);the eastern portion was dominated by short-duration convective precipitation with HRR > 20 mm h~(-1).The contributions of convective precipitation and cumulus–stratus mixed precipitation to the total rainfall of the southern and middle rain belts were broadly equivalent.(4) The local HRR maxima located at the transition zone from the plain to the mountains were induced by moderate storm-scale convective cells with active warm-rain processes and large number of small-sized rain droplets.(5) During the devastating rainfall event,it was observed that the rainfall peaked at around 1800 local time(LT) every day over the upstream plain area(no diurnal cycle of rainfall was observed in relation to the accumulated rainfall centers over mountain areas).This was attributable to convective activities along the storm propagation path,which was a result of the more unstable stratification with a suitable steering mechanism that was related to afternoon solar heating and enhanced water vapor.The findings of this study improve our understanding and knowledge of the extreme precipitation that can develop from the plain to the mountains in North China.展开更多
Hydrazine is extremely toxic and causes severe harm to human body.Herein,a novel fluorescent probe 4-oxo-2-styryl-4H-chromen-3-yl thiophene-2-carboxylate(FHT)was synthesized for detecting hydrazine by using natural ci...Hydrazine is extremely toxic and causes severe harm to human body.Herein,a novel fluorescent probe 4-oxo-2-styryl-4H-chromen-3-yl thiophene-2-carboxylate(FHT)was synthesized for detecting hydrazine by using natural cinnamaldehyde as starting material.This probe exhibited significantly enhanced fluorescence response towards hydrazine over various common metal ions,anions,and amine compounds.The detection limit of probe FHT for hydrazine was as low as 0.14μmol·L^(-1),significantly lower than that of the threshold value of 0.312μmoi·L^(-1),imposed by the Environmental Protection Agency.Moreover,the proposed probe was able to detect hydrazine within wide pH(5-10)and linear detection ranges(0-110μmol·L^(-1)).This probe was employed for determining trace hydrazine in different environmental water samples.The probe FHT-loaded filter paper strips werea able to conveniently detect hydrazine of low concentration through distinct naked-eye and fluorescent color changes.Importantly,the probe FHT with low cytotoxicitywas successfullyapplied to visualize hydrazine in living Hela cells and zebrafish.展开更多
This paper reviews the major progress on development of the science and prediction of heavy rainfall over China since the beginning of the reform and opening-up of new China(roughly between 1980 and 2019).The progress...This paper reviews the major progress on development of the science and prediction of heavy rainfall over China since the beginning of the reform and opening-up of new China(roughly between 1980 and 2019).The progress of research on the physical mechanisms of heavy rainfall over China is summarized from three perspectives:1)the relevant synoptic weather systems,2)heavy rainfall in major sub-regions of China,and 3)heavy rainfall induced by typhoons.The development and application of forecasting techniques for heavy rainfall are summarized in terms of numerical weather prediction techniques and objective forecasting methods.Greatly aided by the rapid progress in meteorological observing technology and substantial improvement in electronic computing,studies of heavy rainfall in China have advanced to investigating the evolution of heavy-rain-producing storms and observational analysis of the cloud microphysical features.A deeper and more systematic understanding of the synoptic systems of importance to the production of heavy rainfall has also been developed.Operational forecast of heavy rainfall in China has changed from subjective weather event forecasts to a combination of both subjective and objective quantitative precipitation forecasts,and is now advancing toward probabilistic quantitative precipitation forecasts with the provision of forecast uncertainty information.展开更多
基金supported by the Open Foundation of State key Laboratory of Networking and Switching Technology(Beijing University of Posts and Telecommunications)(SKLNST-2021-1-18)the General Program of Natural Science Foundation of Chongqing(cstc2020jcyj-msxmX1021)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(KJZD-K202000602)Chongqing graduate research and innovation project(CYS22478).
文摘Mobile Crowd Sensing(MCS)is an emerging paradigm that leverages sensor-equipped smart devices to collect data.The introduction of MCS also poses some challenges such as providing highquality data for upper layer MCS applications,which requires adequate participants.However,recruiting enough participants to provide the sensing data for free is hard for the MCS platform under a limited budget,which may lead to a low coverage ratio of sensing area.This paper proposes a novel method to choose participants uniformly distributed in a specific sensing area based on the mobility patterns of mobile users.The method consists of two steps:(1)A second-order Markov chain is used to predict the next positions of users,and select users whose next places are in the target sensing area to form a candidate pool.(2)The Average Entropy(DAE)is proposed to measure the distribution of participants.The participant maximizing the DAE value of a specific sensing area with different granular sub-areas is chosen to maximize the coverage ratio of the sensing area.Experimental results show that the proposed method can maximize the coverage ratio of a sensing area under different partition granularities.
文摘Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.
文摘It is inevitable that Connected and Autonomous Vehicles (CAVs) will be a major focus of transportation and the automotive industry with increased use in future traffic system analysis. Numerous studies have focused on the evaluation and potential development of CAVs technology;however, pedestrians and bicyclists, as two essential and important modes of the road users have seen little to no coverage. In response to the need for analyzing the impact of CAVs on non-motorized transportation, this paper develops a new model for the evaluation of the Level of Service (LOS) for pedestrians in a CAVs environment based on the Highway Capacity Manual (HCM). The HCM provides a methodology to assess the level of service for pedestrians and bicyclists on various types of intersections in urban areas. Five scenarios were created for simulation via VISSIM (a software) that corresponds to the different proportions of the CAVs and different signal systems in a typical traffic environment. Alternatively, the Surrogate Safety Assessment Model (SSAM) was selected for analyzing the safety performance of the five scenarios. Through computing and analyzing the results of simulation and SSAM, the latter portion of this paper focuses on the development of a new model for evaluating pedestrian LOS in urban areas which are based upon HCM standards which are suitable for CAVs environments. The results of this study are intended to inform the future efforts of engineers and/or policymakers and to provide them with a tool to conduct a comparison of capacity and LOS related to the impact of CAVs on pedestrians during the process of a transportation system transition to CAVs.
文摘Bicycling is an important way for college students and employees to get around campuses. With a rise in bicycling on campuses there comes a rise in bicycle collisions with pedestrians walking to and from classes and work. The literature review showed many papers involving bicycle conflict modeling but on roads with motor vehicles. While some aspects of this research can be applied to non-motorized paths, there is a lack of research strictly focusing on only bicycles and pedestrians. This study aims to fill this knowledge gap by developing a model to identify locations on roads and paths (hotspots) on college campuses that are likely to have a bicycle collision and predict the likelihood of a serious bicycle crash on a non-motorized path based on the characteristics of the path. This study identifies those interactions between bicyclists and pedestrians on non-motorized paths on a suburban college campus in Newark, USA. Findings suggest that pedestrian density of a path is a major factor in the maximum speed bicyclists can achieve. The wider the path is, the higher the maximum speed is that a bicyclist can obtain. This is because a wider path width decreases the pedestrian density. The grade of the path has little effect on bicycle speeds. The results of the models were displayed on a GIS map that is visually appealing to a viewer. The paths were color coded based on their level of safety, so it is easy to observe problematic areas of the network. This technique can be applied to the entire campus network of non-motorized paths to study the whole system. This can then be used by planners and designers to identify areas that need upgrading and improve the overall safety of the non-motorized path system.
文摘This paper introduces the solidworks design flow, design methods and design principles of desk lamp. And we use the ergonomics principle, analysis the function of each part of the lamp, and analyses the design of lamp components, to meet user needs in the bedroom, do practical, human nature and convenient lamp. The application shows that the use of this software can make easier the realization of the design of the parts with complex shape, raise the design efficiency, optimize the product structure and save the cost.
基金supported by Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030004)National Natural Science Foundation of China(Grant Nos.41775050,42030610,41775002,42005008,41975031)the Basic Research Fund of the Chinese Academy of Meteorological Sciences(Grant No.2020Z010).
文摘Using the high spatiotemporal resolution(2 km-and-10 min)data from the Advanced Himawari Imager onboard the Himawari-8 satellite,this study documents the fine-scale characteristics of daytime cloud regimes(CRs)over coastal South China during the pre-summer rainy season(April–June).Six CRs(CR1–CR6)are identified based on the joint frequency distribution of cloud top brightness temperature and cloud optical thickness,namely,the optically thin-to-moderate cloud mixture,optically thin warm clouds with cirrus,optically thick warm clouds,weak convective cloud mixture,strong convective clouds,and extreme,deep convective clouds.The optically thick warm clouds are the major CR during April and May,with higher frequencies over land,especially along the urban agglomeration,rather than the offshore which may be an indicator of the higher aerosol concentrations being a contributing factor over the cities.The CRs with weak convective cloud mixtures and strong convective clouds appear more frequently over the land,while the two CRs with optically thinner clouds occur mainly offshore.Synoptic flow patterns(SPs)are objectively identified and examined focusing on those favoring the two major rainproducing CRs(CR5 and CR6)and the highly reflective CR with optically thick warm clouds(CR3).The two SPs favoring CR5 and CR6 are characterized by abundant moisture with low-level jets after monsoon onset,and a northwest highsoutheast low pattern with strong dynamic convergence along the coastline,respectively.The non-convective CR3 with high reflectance is related to a SP that features the western North Pacific subtropical high extending more westward,leading to a moderate moisture supply and a wide range of convective available potential energy,but also,large convective inhibition.
文摘This work proposes a novel heating and cooling system,with incorporated thermoelectric module,that can achieve energy balance using a self-water supply heat exchange subsystem.The thermoelectric effect is used to achieve controlled and adjustable heating of the circulating water.Simulations were conducted to study the thermal performance of the system while it simultaneously produces hot and cold water,with different working conditions for the hot-and cold-side water outlets.The results show that the water temperature at the hot side outlet increases from 32℃to 75℃when the power increases from 4.5 to 50 W.Additionally,the use of thermoelectric modules to heat water and recover waste heat is 22%more efficient than ordinary electric water heating systems.
文摘In addition to experiencing shortage in LTC workforce, some existing facilities are unable to provide quality service, since they were designed and built decades ago. Thus, the renovation of outdated LTC facilities is currently an unavoidable issue. In this paper, some contemporary practices are presented related to renovating old LTC facilities to improve the quality of service. The most important concept is the person-centered design. Some other elements include the importance of natural lighting for residents, proper practices of flooring and picking doors, some details in home-like design, new guidelines for resident rooms’ design, and other miscellaneous issues. Furthermore, the latest Americans with Disabilities Act (ADA) compliance protocols are reviewed, and some crucial elements are discussed to ensure the renovations will make the facilities compliant with the current standards.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.41775050,91937301,41775002,42005008)the Science Development Fund of Chinese of Academy of Meteorological Sciences(2020KJ022).
文摘A sustained heavy rainfall event occurred over the Sichuan basin in southwest China during 10–18 August 2020,showing pronounced diurnal rainfall variations with nighttime peak and afternoon minimum values,except on the first day.Results show that the westward extension of the anomalously strong western Pacific subtropical high was conducive to the maintenance of a southerly low-level jet(LLJ)in and to the southeast of the basin,which favored continuous water vapor transport and abnormally high precipitable water in the basin.The diurnal cycle of rainfall over the basin was closely related to the periodic oscillation of the LLJ in both wind speed and direction that was caused by the combination of inertial oscillation and terrain thermal forcing.The nocturnally enhanced rainfall was produced by moist convection mostly initiated during the evening hours over the southwest part of the basin where high convective available potential energy with moister near-surface moist air was present.The convective initiation took place as cold air from either previous precipitating clouds from the western Sichuan Plateau or a larger-scale northerly flow met a warm and humid current from the south.It was the slantwise lifting of the warm,moist airflow above the cold air,often facilitated by southwest vortices and quasi-geostrophic ascent,that released the convective instability and produced heavy rainfall.
文摘Heavy ion beams with high linear energy transfer exhibit more beneifcial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irra-diation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy;subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunolfuorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was signiifcantly decreased, and there was ev-idence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our ifnd-ings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation.
文摘Traditionally, the process used by public transportation entities to determine the acquisition strategy for new vehicle asset is based upon a broad range of criteria. Vehicle cost has been cited as one of the more critical factors which decision makers consider. It is currently a common practice to consider other factors (life-cycle cost, fuel efficiency, vehicle reliability, environmental effects, etc.) that contribute to a more comprehensive approach. This study investigates the next generation of advancements in decision making tools in the area of the application of methods to quantify and manage uncertainty. In particular, the uncertainty comes from the public policy arena where future policy and regulations are not always based upon logical and predictable processes. The fleet decision making process in most governmental agencies is a very complex and interdependent activity. There are always competing forces and agendas within the view of the decision maker. Rarely is the decision maker a single person although, within the transit environment, there is often one person charged with the responsibility of fleet management. The focus of this research examines the decision making of the general transit agency community via the development of an expert systems prototype tool. A computer-based prototype system is developed which provide an expert knowledge-based recommendation, based upon variable user inputs. The results shown in this study show that a decision making tool for the management of transit system alternate fuel vehicle assets can be modeled and tested. The direct users of this research are the transit agency administrations. The results can be used by the management teams as a reliable input to inform their urban transit buses expansion decision making process.
文摘The travel time data collection method is used to assist the congestion management. The use of traditional sensors (e.g. inductive loops, AVI sensors) or more recent Bluetooth sensors installed on major roads for collecting data is not sufficient because of their limited coverage and expensive costs for installation and maintenance. Application of the Global Positioning Systems (GPS) in travel time and delay data collections is proven to be efficient in terms of accuracy, level of details for the data and required data collection of man-power. While data collection automation is improved by the GPS technique, human errors can easily find their way through the post-processing phase, and therefore data post-processing remains a challenge especially in case of big projects with high amount of data. This paper introduces a stand-alone post-processing tool called GPS Calculator, which provides an easy-to-use environment to carry out data post-processing. This is a Visual Basic application that processes the data files obtained in the field and integrates them into Geographic Information Systems (GIS) for analysis and representation. The results show that this tool obtains similar results to the currently used data post-processing method, reduces the post-processing effort, and also eliminates the need for the second person during the data collection.
文摘Travel time and delay are among the most important measures for gauging a transportation system’s performance. To address the growing problem of congestion in the US, transportation planning legislation mandated the monitoring and analysis of system performance and produced a renewed interest in travel time and delay studies. The use of traditional sensors installed on major roads (e.g. inductive loops) for collecting data is necessary but not sufficient because of their limited coverage and expensive costs for setting up and maintaining the required infrastructure. The GPS-based techniques employed by the University of Delaware have evolved into an automated system, which provides more realistic experience of a traffic flow throughout the road links. However, human error and the weaknesses of using GPS devices in urban settings still have the potential to create inaccuracies. By simultaneously collecting data using three different techniques, the accuracy of the GPS positioning data and the resulting travel time and delay values could be objectively compared for automation and statistically compared for accuracy. It was found that the new technique provided the greatest automation requiring minimal attention of the data collectors and automatically processing the data sets. The data samples were statistically analyzed by using a combination of parametric and nonparametric statistical tests. This analysis greatly favored the GeoStats GPS method over the rest methods.
基金supports of Special Foundation for State Major Basic Research Program of China(Grant No.2021YFD2101000).
文摘Corn to sugar process has long faced the risks of high energy consumption and thin profits.However,it’s hard to upgrade or optimize the process based on mechanism unit operation models due to the high complexity of the related processes.Big data technology provides a promising solution as its ability to turn huge amounts of data into insights for operational decisions.In this paper,a neural network-based production process modeling and variable importance analysis approach is proposed for corn to sugar processes,which contains data preprocessing,dimensionality reduction,multilayer perceptron/convolutional neural network/recurrent neural network based modeling and extended weights connection method.In the established model,dextrose equivalent value is selected as the output,and 654 sites from the DCS system are selected as the inputs.LASSO analysis is first applied to reduce the data dimension to 155,then the inputs are dimensionalized to 50 by means of genetic algorithm optimization.Ultimately,variable importance analysis is carried out by the extended weight connection method,and 20 of the most important sites are selected for each neural network.The results indicate that the multilayer perceptron and recurrent neural network models have a relative error of less than 0.1%,which have a better prediction result than other models,and the 20 most important sites selected have better explicable performance.The major contributions derived from this work are of significant aid in process simulation model with high accuracy and process optimization based on the selected most important sites to maintain high quality and stable production for corn to sugar processes.
基金Supported by the National Key Research and Development Program of China(2022YFC3003903)National Natural Science Foundation of China(42030610)+1 种基金Basic Research Fund of Chinese Academy of Meteorological Sciences(2023Z001 and 2023Z020)Development Fund of Chinese Academy of Meteorological Sciences(2023KJ026)。
文摘This study examined the rainfall characteristics and related synoptic processes of two extreme rainfall events that affected North China during 29 July–1 August 2023(“23·7”rainstorm)and 3–5 August 1996(“96·8”rainstorm),respectively.A stable dual-typhoon circulation pattern was observed in both rainstorm events.The surviving vortex of a landed typhoon,slowly approaching the rainstorm region,was blocked by a high-pressure system as it moved northwestward.Meanwhile,the second typhoon over the western Pacific Ocean facilitated remote northward transport of moisture.The low-level jet between the surviving vortex and the western Pacific subtropical high relayed moist warm air from the area of the South China Sea and western Pacific into the rainstorm region.Although the circulation patterns are similar,the stratification conditions,driving factors,and moisture budget of the two rainstorms differed during the main period of rainfall.The“23·7”rainstorm was categorized as warm-sector rainfall,as a result of the lifting of warm moist air over the eastern foothills of Taihang Mountains.In comparison with the situation of the“96·8”rainstorm,the surviving vortex of the“23·7”rainstorm traveled further northeastward and directly impacted the occurrence and progression of the rainfall,leading to relative northward displacement of the rainfall center,while the stronger net inward moisture flux caused greater regional average rainfall.The“96·8”rainstorm was broadly analogous to precipitation of a cold front,and the rainfall center was observed in the convergence area of warm and cold air masses before the mountains;the surviving vortex did not exert direct impact on the rainfall;and the more unstable stratification led to stronger hourly rainfall.The results derived through comparison of the two rainstorms could serve as valuable scientific reference for operational forecasting of heavy rainfall under similar environmental conditions over North China.
基金Supported by the National Key Research and Development Program of China (2022YFC3003903)National Natural Science Foundation of China (42005008)+1 种基金Joint Research Project for Meteorological Capacity Improvement (23NLTSZ007)Basic Research Fund of Chinese Academy of Meteorological Sciences (2023Z001)。
文摘North China experienced devastating rainfall from 29 July to 1 August 2023,which caused substantial flooding and damage.This study analyzed observations from surface rain gauges and S-band dual-polarization radars to reveal the following unique features of the precipitation evolution from the plain to the mountains during this event.(1) The total rainfall was found concentrated along the Taihang Mountains at elevations generally > 200 m,and its spatiotemporal evolution was closely associated with northward-moving low-level jets.(2) Storms propagated northwestward with southeasterly steering winds,producing continuous rainfall along the eastern slopes of the Taihang Mountains owing to mountain blocking,which resulted in the formation of local centers of precipitation maxima.However,most rainfall episodes with an extreme hourly rainfall rate(HRR),corresponding to large horizontal wind shear at low levels,actively occurred in the plain area to the east of the Taihang Mountains.(3) The western portion of the extreme heavy rain belt in the north was mainly caused by long-lasting cumulus–stratus mixed precipitation with HRR< 20 mm h~(-1);the eastern portion was dominated by short-duration convective precipitation with HRR > 20 mm h~(-1).The contributions of convective precipitation and cumulus–stratus mixed precipitation to the total rainfall of the southern and middle rain belts were broadly equivalent.(4) The local HRR maxima located at the transition zone from the plain to the mountains were induced by moderate storm-scale convective cells with active warm-rain processes and large number of small-sized rain droplets.(5) During the devastating rainfall event,it was observed that the rainfall peaked at around 1800 local time(LT) every day over the upstream plain area(no diurnal cycle of rainfall was observed in relation to the accumulated rainfall centers over mountain areas).This was attributable to convective activities along the storm propagation path,which was a result of the more unstable stratification with a suitable steering mechanism that was related to afternoon solar heating and enhanced water vapor.The findings of this study improve our understanding and knowledge of the extreme precipitation that can develop from the plain to the mountains in North China.
基金the National Natural Science Foundation of China(Grant Nos.32071707 and 32101466)the Natural Science Foundation of Jiangsu Province(No.BK20210624).
文摘Hydrazine is extremely toxic and causes severe harm to human body.Herein,a novel fluorescent probe 4-oxo-2-styryl-4H-chromen-3-yl thiophene-2-carboxylate(FHT)was synthesized for detecting hydrazine by using natural cinnamaldehyde as starting material.This probe exhibited significantly enhanced fluorescence response towards hydrazine over various common metal ions,anions,and amine compounds.The detection limit of probe FHT for hydrazine was as low as 0.14μmol·L^(-1),significantly lower than that of the threshold value of 0.312μmoi·L^(-1),imposed by the Environmental Protection Agency.Moreover,the proposed probe was able to detect hydrazine within wide pH(5-10)and linear detection ranges(0-110μmol·L^(-1)).This probe was employed for determining trace hydrazine in different environmental water samples.The probe FHT-loaded filter paper strips werea able to conveniently detect hydrazine of low concentration through distinct naked-eye and fluorescent color changes.Importantly,the probe FHT with low cytotoxicitywas successfullyapplied to visualize hydrazine in living Hela cells and zebrafish.
基金Supported by the National Key Research and Development Program of China(2018YFC1507400)National Natural Science Foundation of China(41775050).
文摘This paper reviews the major progress on development of the science and prediction of heavy rainfall over China since the beginning of the reform and opening-up of new China(roughly between 1980 and 2019).The progress of research on the physical mechanisms of heavy rainfall over China is summarized from three perspectives:1)the relevant synoptic weather systems,2)heavy rainfall in major sub-regions of China,and 3)heavy rainfall induced by typhoons.The development and application of forecasting techniques for heavy rainfall are summarized in terms of numerical weather prediction techniques and objective forecasting methods.Greatly aided by the rapid progress in meteorological observing technology and substantial improvement in electronic computing,studies of heavy rainfall in China have advanced to investigating the evolution of heavy-rain-producing storms and observational analysis of the cloud microphysical features.A deeper and more systematic understanding of the synoptic systems of importance to the production of heavy rainfall has also been developed.Operational forecast of heavy rainfall in China has changed from subjective weather event forecasts to a combination of both subjective and objective quantitative precipitation forecasts,and is now advancing toward probabilistic quantitative precipitation forecasts with the provision of forecast uncertainty information.
