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AbstractThis study investigates the impacts of various factors on e-bike riders’ injury severity in crashes with motor vehicles, based on the in-vehicle recording video crash data in China. Variables from human factors, vehicle characteristics, road conditions, and environmental attributes are extracted from the video, especially for drivers and riders’ illegal and avoidance behaviour before the crash, and sun shade canopy use. Results of mixed logit models reveal that drivers’ speeding, running red lights, slow-down and swerve behaviour, light trucks, heavy trucks, and buses have significantly varied impacts on riders’ injury. Moreover, both drivers and riders’ illegal behaviour leads to an increased injury, while their avoidance behaviour before crashes can protect riders. In addition, types of visual obstacles, accidents occurring at night, large vehicles’ involvement, and the application of sunshade canopies by riders increased the probability of severe injury, while helmet use can protect riders in accidents with motor vehicles. [ABSTRACT FROM AUTHOR]

Work zone areas are frequent congested sections considered as the freeway bottleneck. Connected and autonomous vehicle (CAV) trajectory optimization can improve the operating efficiency in bottleneck areas by harmonizing vehicles' manipulations. This study presents a joint trajectory optimization of cooperative lane changing, merging, and car-following actions for CAV control at a local merging point together with upstream points. The multiagent reinforcement learning (MARL) method is applied in this system, with one agent providing a merging advisory service at the merging point and controlling the inner-lane vehicles' headway for smooth outer-lane vehicle merging, while other agents provide lane-changing advisory services at advance lane-changing points to control how vehicles make lane changes in advance and perform corresponding headway adjustment, similar to and jointly with the merging advisory service. Uniting all agents, the coordination graph (CG) method is applied to seek the global optimum, overcoming the exponential growth problem in MARL. Using MATLAB and the VISSIM COM interface, an online simulation platform is established. The simulation results show that MARL is effective for online computation with in-timing response. More importantly, comparisons of the results obtained in various scenarios demonstrate that the proposed system obtained smoother vehicle trajectories in all controlled sections, rather than only in the merging area, indicating that it can achieve better traffic conditions in freeway work zone areas., Author(s): Tong Zhu (corresponding author) [1]; Xiaohu Li [2]; Wei Fan [3]; Changshuai Wang [4]; Haoxue Liu [5]; Runqing Zhao [6] 1. Introduction Work zone areas are bottleneck sections affecting [...]

Electric bicyclists are vulnerable road users and play an important role in traffic safety. The focus of this research is on analyzing cyclists' injury severity in vehicle-electric bicycle collisions. It is an exploratory analysis that was conducted based on samples obtained from video data provided by the police of Xi'an China. Three types of severity include fatal, injury, and property-damage-only (PDO). A random parameter logit (RPL) model was specified to gain more insights into factors related to the injury severity level, including human behaviors, vehicle characteristics, roadway attributes, and environmental conditions. Some factors not included in previous research were introduced into this study, especially precrash behaviors of drivers and cyclists. The direct pseudo-elasticity effects of variables were compared to investigate the stability of individual parameter estimates on the severity categories. The results indicated that variables that significantly increment the probability of fatal accidents were as follows: driver violation behaviors (speeding, red-light violation, driving in the opposite direction), cyclist violation behaviors (speeding, red-light violation), day of time (nighttime), visibility restrictions (fixed obstacles), and vehicle type (larger bus, small truck, and larger truck). Based on these findings, we suggested measures such as strengthening law enforcement by installing cameras, implementing zero tolerance for cyclist violations, promoting education by completing training courses for cyclists, and enhancing traffic safety awareness through educational activities. The research results can provide a theoretical basis for formulating strategies to improve cyclist safety., Author(s): Fei Ye (corresponding author) [1,2]; Changshuai Wang [3]; Wen Cheng [1,2]; Haoxue Liu [1] 1. Introduction Electric bicycle has become a popular travel tool due to the advantages of [...]

The freeway's operation safety has attracted wide attention. In order to mitigate the losses brought on by traffic accidents on freeways, discrete choice models were constructed based on the statistical analysis method to quantitatively analyze the significance and magnitude of the impact of multiple dimensional factors on crash severity. Based on 1154 accidents that occurred on Zhejiang Province's Hang-Jin-Qu Fressway from 2013 to 2018, the distribution characteristics of crash severity were analyzed. The dependent variable was the crash injury severity, which was categorized into property damage only (PDO), injury, and fatal. As independent variables, 15 candidate variables representing four aspects, including driver, vehicle, road, and environmental conditions, were chosen. Considering the ordered characteristics of the variables, the models developed included the ordered logit, the generalized ordered logit, and the partial proportional odds models. The Brant test found that the previous two models had difficulty dealing with the problem of partial variables that did not fit the parallel-lines assumption, and the conclusions were finally discussed through the partial proportional odds model results. The findings indicate that 11 factors have significant consequences. Five variables, namely "mountainous", "female", "driving experience 2- years", "large vehicle responsible", and "vehicle not going straight", violated the parallel-lines assumption. Female drivers and drivers aged 55+ years were more likely to suffer injuries and fatalities in collisions with guardrails and other objects. Large vehicles being involved and vehicles not going straight enhanced the likelihood of injury and fatal outcomes when drivers had 2- years of experience. Wet-skid road conditions enhanced the likelihood of injury accidents, and driving at nighttime without lighting increased the likelihood of fatal accidents. Departments responsible for traffic management can take full account of these variations and develop focused proposals for improvement. [ABSTRACT FROM AUTHOR]

The hot deformation behavior of a Fe–Ni–Cr‐based superalloy is investigated by electron backscattered diffraction (EBSD) and processing map. The results show that the strain has an obvious effect on hot deformation. The flow instability domain at low temperature decreases with increasing strain. However, it expands with the increasing strain at high temperature. The optimized hot working domain at high temperature moves from low strain rate to high strain rate with the increase in strain. The hot deformation behavior of the alloy is correlated with dynamic recrystallization (DRX). The low fraction of DRX and local flow are responsible for the flow instability at low temperature. The DRX fraction rises with the increase in strain, which results in the reduction of flow instability domain at low temperature. The DRX grains grow rapidly at high temperature and low strain rate with increasing strain. The poor deformation compatibility between the large grains at high strain hinders the multiround DRX, which expands the flow instability at low strain rate and high temperature. The optimized hot working domain transforms from low strain rate to 2.0–10 s−1 at 1050–1170 °C with the true strain of 1.2 due to the appropriate DRX process. [ABSTRACT FROM AUTHOR]

Cast alloy IN625 is a candidate Ni-base alloy for advanced ultra-supercritical (A-USC) power plants. The aim of this study was to investigate the influences of Nb on δ phase precipitation and the tensile properties in this alloy. The results show that the δ phase is easy to precipitate after long-term aging at 700 °C (the service temperature of A-USC power plants) and it is strongly affected by the content of Nb in the alloy. The strength of alloys after aging at 700 °C for 10,000 h increases with the increasing Nb content and also increases sharply when compared to that of as-heat-treated alloys. The increase in strength is found to be primarily associated with the precipitation of the δ phase. [ABSTRACT FROM AUTHOR]

The effects of Mo content on the microstructural characteristics and mechanical properties of a Ni–Fe–Cr based alloy with low gamma prime (γ′) volume fraction, considered as boiler materials in 700 °C advanced ultra-supercritical (A-USC) coal-fired power plants, were studied in this paper. Detailed investigations reveal that the alloys with different Mo contents have similar microstructural characteristics, except the γ–γ′ misfit after standard heat treatment. The major precipitates of the alloys are all spherical γ′, blocky MC and discrete M23C6. During long-term thermal exposure at 700–750 °C, the variation of Mo content has no notable influence on primary MC degeneration, precipitation and growth of M23C6 carbide. The coarsening behavior of γ′ phase of the alloys with different Mo contents all follows Ostwald ripening kinetics. The higher Mo content can decrease γ′ coarsening rate due to the increase of the activation energy for γ′ coarsening. After standard heat treatment, the tensile properties of the alloys with different Mo contents are almost same. However, the stress rupture life increases significantly with increasing Mo content, but the ductility has no obvious change. The effects of Mo on the diffusion processes, the stacking fault energy and γ–γ′ misfit are assumed to cause the increase of the stress rupture life. [ABSTRACT FROM AUTHOR]

Microstructural changes and their effect on tensile properties of a Ni-Fe based alloy, considered as boiler materials in 700 °C advanced ultra-supercritical (A-USC) coal-fired power plants, were investigated during exposure at 700–800 °C for up to 30000 h. The results show that the major precipitates are still spherical γ׳, blocky MC and discrete particle-like M 23 C 6 after long-term thermal exposure. No η or σ and other detrimental phases were observed. The main changes in microstructure are γ′ coarsening and the precipitation and growth of M 23 C 6 carbide. The coarsening behavior of γ′ precipitates is in good accordance with the prediction of the Lifshitz-Slozov-Wagner (LSW) theory during exposure at 700 °C. However, it deviates from the prediction of LSW theory at 750 and 800 °C and an anomalous coarsening behavior of γ′ precipitates was observed. For M 23 C 6 carbide, the size and amount first increase, and then keep almost constant with increasing exposure time at 700 and 750 °C, but the dissolution of M 23 C 6 carbide appears at 800 °C. The yield strength first increases and then slightly decreases with increasing exposure time at 700 °C, while it decreases gradually at 750 °C and decreases drastically and then keeps almost constant at 800 °C. However, the yield strength almost keeps the same level as that of the samples after standard heat treatment even if after exposure at 700 °C for 30000 h. The elongation has no obvious change with increasing exposure time at 700 and 750 °C, but it increases gradually at 800 °C. The changes in yield strength and ductility can be attributed to the γ′ coarsening and the evolution of M 23 C 6 carbide. [ABSTRACT FROM AUTHOR]

Abstract: The melt superheating treatment is carried out for DZ125 superalloy during directional solidification. Under the same thermal gradient and solidification velocity, the microstructure evolution of directionally solidified DZ125 superalloy is systematically investigated by changing the melt superheating temperature. The results show that the dendrite is refined with the melt superheating temperature increasing from 1500°C to 1650°C. However, it becomes coarse after the melt superheating treatment at 1750°C. The dendrite segregation first reduces with the increase of melt superheating temperature between 1500°C and 1650°C, but becomes more severe when the superheating temperature is higher than 1650°C. The carbide morphology presents script-like when the melt superheating temperature is below 1600°C. Further increasing the melt superheating temperature, it is mainly blocky and nodular. Moreover, the reason of microstructure evolution with melt superheating treatment is discussed. The results are useful for promoting the development of high quality directionally solidified superalloy. [ABSTRACT FROM AUTHOR]

This study is focused on the effect of boron additions on the microstructure stability and mechanical properties of a Ni-Cr based superalloy designed for application of 700 °C advanced ultra-supercritical units component. The results show that boron in the content range of 25–75 ppm has no obvious influence on as-cast and heat-treated microstructure characteristics compared with that of the alloy without boron. During long-term thermal exposure, the variation of B content has no obvious effect on γ′′ coarsening, δ phase precipitation and MC carbide degeneration, but inhibits the agglomeration of M 23 C 6 carbide along grain boundary. According to the mechanical property analysis, the boron additions contribute to mainly tensile ductility especially the elongation of whether the heat treated alloy or the long-term thermal exposed alloy. The strength especially yield strength of the B doped alloy almost keeps the same level as that of the B-free alloy. Furthermore, the SEM fractography shows a change from intergranular fracture to a mixed fracture and the dimples on fracture surface obviously increase with the addition of boron. The mechanism discussion reveals that the segregation of boron at grain boundary resulted in the improvement of grain boundary cohesion and the optimization of carbides distribution at grain boundary. The strengthening mechanism of δ phase is confirmed as its obstacle effect to dislocation movement. [ABSTRACT FROM AUTHOR]

Intracrine androgen synthesis plays a critical role in the development of castration-resistant prostate cancer (CRPC). Aldo-keto reductase family 1 member C3 (AKR1C3) is a vital enzyme in the intracrine androgen synthesis pathway. In this study, mesoporous silica nanoparticles (MSNs) were employed to deliver small interfering RNA targeting AKR1C3 (siAKR1C3) to downregulate AKR1C3 expression in CPRC cells. The optimal weight ratio of MSNs/siAKR1C3 was determined by a gel retardation assay. Prostate cancer cells such as VCaP cells, which intracrinally express AKR1C3, and LNCaP-AKR1C3 cells stably transfected with AKR1C3 were used to investigate the antitumour effect of MSNs-siAKR1C3. Fluorescence detection and Western blot analyses were applied to confirm the entrance of MSNs-siAKR1C3 into the cells. A SRB (Sulforhodamine B) assay was employed to assess the cell viability, and a radioimmunoassay was used to measure the androgen concentration. Moreover, real-time PCR (RT-PCR), Western blot analysis and ELISA were used to determine the transcription and expression of prostate-specific antigen (PSA), AKR1C3 and androgen receptor (AR). Meanwhile, a reporter gene assay was performed to determine the AR activity. Additionally, a castrated nude mouse xenograft tumour model was produced to verify the inhibitory effect of MSNs-siAKR1C3 in vivo. The results showed that the optimal weight ratio of MSNs/siAKR1C3 was 140:1, and the complex could effectively enter cells, downregulate AKR1C3 expression, reduce the androgen concentration, inhibit AR activation, and inhibit CRPC development both in vitro and in vivo. These results indicate that decreasing intracrine androgen synthesis and inactivating AR signals by MSNs-siAKR1C3 may be a potential effective method for CRPC treatment. • Mesoporous Silica Nanoparticles can carry siRNA targeting AKR1C3 (MSN-siAKR1C3). • MSN-siAKR1C3 inhibits castration-resistant prostate cancer in vitro and in vivo. • MSN-siAKR1C3 decreases androgen synthesis and inactivates androgen receptor signals. • MSN-siAKR1C3 is a simple, low-cost, and safe drug in prostate cancer treatment. • Provide new therapeutic strategy for castration-resistant prostate cancer. [ABSTRACT FROM AUTHOR]