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This study selected the Yangtze River Delta urban agglomeration as the research area, considering the current status of its transportation development to construct an urban agglomeration land transportation integration index system and to evaluate the development of the area's transportation integration. The study examined the influence mechanism of transportation infrastructure on service industry agglomeration. The results were as follows: (1) From 2011 to 2020, the Yangtze River Delta urban agglomeration land transportation integration index showed a clear upward trend. (2) The development of the integration level of local transportation has a certain inhibitory effect on the agglomeration of local service industries. The transportation integration of the Yangtze River Delta urban agglomeration played an important role in promoting the agglomeration of local wholesale and retail industries and transportation, storage, and postal services. The labor force and market size also have a significant impact on service agglomeration. (3) The integration of land transport in the urban agglomeration affects the agglomeration of service industries through the knowledge spillover effect caused by the improvement of accessibility, and the impact is heterogeneous. The Yangtze River Delta urban agglomeration needs to accelerate the construction of trans-provincial and trans-municipal transportation infrastructure and to further improve its connectivity level to promote the integrated development of high-quality transportation in this area. [ABSTRACT FROM AUTHOR]

Exploring travel time distribution and variability patterns is essential for reliable route choices and sophisticated traffic management and control. State-of-the-art studies tend to treat different types of roads equally, which fails to provide more detailed analysis of travel time characteristics for each specific road type. In this study, based on a vast amount of probe vehicle data, 200 links inside the Third Ring Road of Beijing, China, were investigated. Four types of roads were covered including urban expressways, auxiliary roads of urban expressways, major roads, and secondary roads. The day-of-week distributions of unit distance travel time were first analyzed. Kolmogorov-Smirnov test, Anderson-Darling test, and chi-squared test were employed to test the goodness-of-fit of different distributions and the results showed lognormal distribution was best-fitted for different time periods and road types compared with normal, gamma, and Weibull distribution. In addition, four reliability measures, that is, unit distance travel time, coefficient of variation, buffer time index, and punctuality rate, were used to explore the day-of-week travel time variability patterns. The results indicated that urban expressways, auxiliary roads of urban expressways, and major roads have regular and distinct morning and afternoon peaks on weekdays. It is noteworthy that in daytime the travel times on auxiliary roads of urban expressways and major roads share similar variability patterns and appear relatively stable and reliable, while urban expressways have most reliable travel times at night. The results of analysis help enable a better understanding of the volatile travel time characteristics of each road type in urban network., 1. Introduction Nowadays, high traffic demand and limited road capacities make people spend much more time on their daily journeys. Travel time reliability (TTR), defined as the level of consistency [...]

Drivers’ risk perception is vital to driving behavior and traffic safety. In the dynamic interaction of a driver-vehicle-environment system, drivers’ risk perception changes dynamically. This study focused on drivers’ risk perception at unsignalized intersections in China and analyzed drivers’ crossing behavior. Based on cognitive psychology theory and an adaptive neuro-fuzzy inference system, quantitative models of drivers’ risk perception were established for the crossing processes between two straight-moving vehicles from the orthogonal direction. The acceptable risk perception levels of drivers were identified using a self-developed data analysis method. Based on game theory, the relationship among the quantitative value of drivers’ risk perception, acceptable risk perception level, and vehicle motion state was analyzed. The models of drivers’ crossing behavior were then established. Finally, the behavior models were validated using data collected from real-world vehicle movements and driver decisions. The results showed that the developed behavior models had both high accuracy and good applicability. This study would provide theoretical and algorithmic references for the microscopic simulation and active safety control system of vehicles.

A large number of road traffic accidents occur each year in China, which results in huge losses to the safety of people’s lives and property. Among all accidents, the accident with over 10 fatalities in one accident is extraordinarily serious, which has immeasurable impact on the security. In this paper, we defined these accidents as serious fatal road traffic accidents (SF-RTAs). The aim of this study was to analyze SF-RTAs in China and its provinces and investigate the causes of SF-RTAs. Firstly, we described and analyzed the annual trend of SF-RTAs based on the data from 1990 to 2014. Then we analyzed region, time and accident type distribution characteristics of SF-RTAs during 2004-2014. Then the main factors influencing SF-RTAs were analyzed by linear regression and decision tree methods. Finally, we proposed corresponding control strategies for preventing SF-RTAs according to the analysis results. It is expected that the findings of this study are useful in indentifying effective prevention measures for serious fatal accidents in China, and protecting human lives and properties.

The effect of connected vehicle environment on the transportation systems and the relationship between the penetration rate of connected vehicle and its efficiency are investigated in this study. An example based on the classical two-route network is adopted in this study, in which the drivers consist of two types: informed and uninformed. The advantages and disadvantages of the connected vehicle environment are analyzed, and the concentration phenomenon is proposed and found to be mitigated when only a fraction of drivers are informed. The simulation tool embodying the characteristics of the connected vehicle environment is developed using the multiagent technology. Finally, different scenarios are simulated, such as the zero-information environment, the full-information environment, and the connected vehicle environment with various penetration rates. Moreover, simulation results of the global performance of the transportation system are compared. The results show that the connected vehicle environment can efficiently improve the performance of the transportation system, while the adverse effects due to concentration rise out from the excessive informed drivers. An optimal penetration rate of the connected vehicles is found to characterize the best performance of the system. These findings can aid in understanding the effect of the connected vehicle environment on the transportation system., 1. Introduction Traffic congestion imposes a high cost on individuals and communities with the rapid growth of vehicle ownership. In addition, the resulting problems, such as vehicle emissions and environmental [...]

A physically-based dynamic simulator has been constructed to investigate the time-dependent behavior of equipment, process, sensor, and control systems for rapid thermal chemical vapor deposition (RTCVD) of polysilicon from Si[H.sub.4]. The simulator captures the essential physics and chemistry of mass transport, heat transfer, and chemical kinetics of the RTCVD process as embodied in equipment. In order to complete the system-level description, reduced-order models are also employed to represent processes involving high complexity of physics. Integration of individual simulator elements for equipment, process, sensors, and control systems enables the evaluation of not only the deposition rate and film thickness, but also of a broad range of dynamic system properties such as equipment performance, gas flow conditions, wafer temperature variation, wafer optical properties (absorptivity/emissivity), reaction gas composition, total process cycle time, consumables volume, and reactant utilization. This makes the simulator directly applicable to the optimization of process recipes and equipment design, to process control strategy, and to fault classification. This case study of polysilicon RTCYD demonstrates 1) that integrated dynamic simulation is a versatile tool for representing system-level dynamics and 2) that such representation is pivotal in successful applications of modeling and simulation for manufacturing optimization and control. Index Terms - CVD, semiconductor process modeling, simulation.

Gas delivery from a liquid source, common in semiconductor manufacturing, raises contamination control concerns not only due to impurity levels in the source. In addition, the lower vapor pressure of impurity species compared to that of the host (source) species causes impurity concentrations in delivered gas to increase as the source is used up. A physics-based dynamic simulator to describe the time-dependent variation of impurity level in such a gas delivery system has been developed and applied to the important case of CHCl[F.sub.2] impurities in host CH[F.sub.3] liquid, as routinely used for dry etching processes. For a cylinder of CH[F.sub.3] liquid with 100 ppm of CHCl[F.sub.2] at 21.1 [degrees] C (70 [degrees] F), the concentration of CHCl[F.sub.2] in the delivered gas is initially [approximately]21 ppm, and rises slowly to [approximately]100 ppm with [approximately]25% of the initial material remaining. With further usage, the CHCl[F.sub.2] level increases quickly to [approximately]350 ppm when [approximately]15% of the initial source material is left; at this point, the source has reached the liquid-dry point, i.e., all the remaining source material is gaseous, and the impurity concentration in delivered gas remains constant at 350 ppm until all material is gone. The time-dependence of CHCl[F.sub.2] impurity concentration is also dependent on the operating temperature of the liquid source: for higher temperatures, the fast rise in impurity concentration and the liquid-dry point occur earlier, while the final impurity level after this point is lower. The dynamic simulator represents a useful tool for avoiding contamination problems with liquid delivery systems and for optimizing materials usage (for cost and environmental benefits) by structuring source usage procedures consistent with contamination-sensitivity of the process. The results also suggest benefits in materials usage if specific source temperatures (different from room temperature) were imposed. The physical basis of the dynamic simulator allows more general application to other systems. Index Terms - CVD, environmental factors, etching, semiconductor manufacturing, simulation.

In the semiconductor manufacturing industry, optimization of advanced equipment and process designs must include both manufacturing metrics (such as cycle time, consumables cost, and product quality) and environmental consequences (such as reactant utilization and by-product emission). We have investigated the optimization of rapid thermal chemical vapor deposition (RTCVD) of polysilicon from Si[H.sub.4] as a function of process parameters using a physically-based dynamic simulation approach. The simulator captures essential time-dependent behaviors of gas flow, heat transfer, reaction chemistry, and sensor and control systems, and is validated by our experimental data. Significant improvements in Si[H.sub.4] utilization (up to 7x) and process cycle time (up to 3x) can be achieved by changes in 1) timing for initiating wafer heating relative to starting process gas flow; 2) process temperature (650-750 [degrees] C); and 3) gas flow rate (100-1000 sccm). Enhanced gas utilization efficiency and reduced process cycle time provide benefits for both environmental considerations and manufacturing productivity (throughput). Dynamic simulation proves to be a versatile and powerful technique for identifying optimal process parameters and for assessing tradeoffs between various manufacturing and environmental metrics. Index Terms - CVD, environmental factors, semiconductor process modeling, simulation.

Background: Quinine (QN) remains an effective drug for malaria treatment. However, quinine resistance (QNR) in Plasmodium falciparum has been reported in many malaria-endemic regions particularly in African countries. Genetic polymorphism of the P. falciparum Na+/H+ exchanger (pfnhe1) is considered to influence QN susceptibility. Here, ms4760 alleles of pfnhe1 were analysed from imported African P. falciparum parasites isolated from returning travellers in Wuhan, Central China.Methods: A total of 204 dried-blood spots were collected during 2011-2016. The polymorphisms of the pfnhe1 gene were determined using nested PCR with DNA sequencing.Results: Sequences were generated for 99.51% (203/204) of the PCR products and 68.63% (140/204) of the isolates were analysed successfully for the pfnhe1 ms4760 haplotypes. In total, 28 distinct ms4760 alleles containing 0 to 5 DNNND and 1 to 3 NHNDNHNNDDD repeats were identified. For the alleles, ms4760-1 (22.86%, 32/140), ms4760-3 (17.86%, 25/140), and ms4760-7 (10.71%, 15/140) were the most prevalent profiles. Furthermore, 5 undescribed ms4760 alleles were reported.Conclusions: The study offers an initial comprehensive analysis of pfnhe1 ms4760 polymorphisms from imported P. falciparum isolates in Wuhan. Pfnhe1 may constitute a good genetic marker to evaluate the prevalence of QNR in malaria-endemic and non-endemic regions. [ABSTRACT FROM AUTHOR]