Feasibility Analysis of Vehicle-to-vehicle Communication on Suburban Road

With the evolution of advanced wireless communication technologies, tremendous efforts have been invested in vehicular networking, particularly the construction of a vehicle-to-vehicle communication system that supports high speed and mobility. In vehicle-to-vehicle communication environment, vehicles constantly exchange information using wireless technology. This paper aims to propose a vehicle-to-vehicle communication system and validate the feasibility of the system on a suburban road in China. Two vehicles were used equipped with IEEE 802.11p based DSRC (Dedicated Short Range Communications) device to construct a vehicle-to-vehicle communication platform. The system architecture consisting of hardware and software was described in details. Then, communication characteristics such as RSSI (Received Signal Strength Indicator), latency and PLR (packet loss rate) were analyzed. Additionally, GPS-related information (such as ground speed and location) was obtained through field test on a suburban road in Shanghai and Taicang City. The test results demonstrate satisfactory performance of the proposed system

Research Advance on Prediction and Optimization for Fracture Propagation in Stimulated Unconventional Reservoirs

AbstractMultistage stimulation horizontal wells are prerequisite technologies for efficient development of unconventional reservoir. However, the induced fracture network morphology from hydraulic fracturing is very complex and affected by many factors, such as the in situ stress, rock mechanical properties, and natural fracture distribution. The large numbers of natural fractures and strong reservoir heterogeneity in unconventional reservoirs result in enhanced complexity of induced fractures from hydraulic fracturing. Accurate description of fracture network morphology and the flow capacity in different fractures form an important basis for production forecasting, evaluation (or optimization) of stimulation design, and development plan optimization. This paper focuses on hydraulic fracturing in unconventional reservoirs and discusses the current research advances from four aspects: (1) the prediction of induced fracture propagation, (2) the simulation of fluid flow in complex fracture networks, (3) the inversion of fracture parameter (fracture porosity, fracture permeability, etc.), and (4) the optimization of hydraulic fracturing in unconventional reservoirs. In addition, this paper provides comparative analysis of the characteristics and shortcomings of the current research by outlining the key technical problems in the study of flow characterization, parameter inversion, and optimization methods for stimulation in unconventional reservoirs. This work can provide a certain guiding role for further research

Generation of pressures over 40 GPa using Kawai-type multi-anvil press with tungsten carbide anvils

We have generated over 40 GPa pressures, namely, 43 and 44 GPa, at ambient temperature and 2000 K, respectively, using Kawai-type multi-anvil presses (KMAP) with tungsten carbide anvils for the first time. These high-pressure generations were achieved by combining the following pressure-generation techniques: (1) precisely aligned guide block systems, (2) high hardness of tungsten carbide, (3) tapering of second-stage anvil faces, (4) materials with high bulk modulus in a high-pressure cell, and (5) high heating efficiency

Design and Implementation of an Emergency Vehicle Signal Preemption System Based on Cooperative Vehicle-Infrastructure Technology

Emergency vehicle is an important part of traffic flow. The efficiency, reliability, and safety of emergency vehicle operations dropped due to increasing traffic congestion. With the advancement of the wireless communication technologies and the development of the vehicle-to-vehicle (v2v) and vehicle-to-infrastructure (v2i) systems, called Cooperative Vehicle-Infrastructure System (CVIS), there is an opportunity to provide appropriate traffic signal preemption for emergency vehicle based on real-ime emergency vehicle data, traffic volume data, and traffic signal timings. This paper describes the design and implementation of an Emergency Vehicle Signal Preemption System (TJ-EVSP) in CVIS environment. The system function, system architecture, and operation strategies were presented. Then, the system was deployed and validated at two adjacent intersections in Taicang City, Jiangsu Province, China. Results show that the proposed system can improve the efficiency of emergency vehicle operations with less waste of traffic resources

Lane-Level Vehicle Trajectory Reckoning for Cooperative Vehicle-Infrastructure System

This paper presents a lane-level positioning method by trajectory reckoning without Global Positioning System (GPS) equipment in the environment of Cooperative Vehicle-Infrastructure System (CVIS). Firstly, the accuracy requirements of vehicle position in CVIS applications and the applicability of GPS positioning methods were analyzed. Then, a trajectory reckoning method based on speed and steering data from vehicle’s Control Area Network (CAN) and roadside calibration facilities was proposed, which consists of three critical models, including real-time estimation of steering angle and vehicle direction, vehicle movement reckoning, and wireless calibration. Finally, the proposed method was validated through simulation and field tests under a variety of traffic conditions. Results show that the accuracy of the reckoned vehicle position can reach the lane level and match the requirements of common CVIS applications

Effect of Slag Compositions on Change Behavior of Nitrogen in Molten Steel

The problem of nitrogen pickup in the smelting process of the electric arc furnace (EAF) has not been solved well. Using seven slag–steel equilibrium experiments and theoretical analysis, the relation of the foaming index and optical basicity with the nitrogen capacity of slag was clarified. Meanwhile, the effect of slag composition on the equilibrium distribution ratio of nitrogen and the mass transfer coefficient of nitrogen pickup was also studied. The results show that, with the increase in slag basicity, the nitrogen pickup amount, nitrogen pickup rate, and nitrogen equilibrium distribution ratio LN increase. Increasing the foaming index of slag and reducing its optical basicity will increase the nitrogen capacity of slag, which is conducive to hindering the nitrogen pickup of molten steel. The relationship between slag optical basicity and nitrogen capacity can be expressed as lgCN = −5.59lgΛ − 12.41. With the increase in the Al2O3 content of slag, the nitrogen pickup amount of molten steel decreases and the nitrogen pickup rate decreases. The test with MgO = 7.5% showed the highest nitrogen pickup rate and the highest nitrogen pickup mass transfer coefficient, which were 0.21 × 10−4%/min and 1.97 × 10−4 cm/s, respectively. The test with Al2O3 = 7.5% in slag showed the lowest nitrogen pickup rate and the lowest nitrogen pickup mass transfer coefficient, which were 0.08 × 10−4%/min and 1.35 × 10−4 cm/s, respectively

Effect of Slag Compositions on Change Behavior of Nitrogen in Molten Steel

The problem of nitrogen pickup in the smelting process of the electric arc furnace (EAF) has not been solved well. Using seven slag–steel equilibrium experiments and theoretical analysis, the relation of the foaming index and optical basicity with the nitrogen capacity of slag was clarified. Meanwhile, the effect of slag composition on the equilibrium distribution ratio of nitrogen and the mass transfer coefficient of nitrogen pickup was also studied. The results show that, with the increase in slag basicity, the nitrogen pickup amount, nitrogen pickup rate, and nitrogen equilibrium distribution ratio LN increase. Increasing the foaming index of slag and reducing its optical basicity will increase the nitrogen capacity of slag, which is conducive to hindering the nitrogen pickup of molten steel. The relationship between slag optical basicity and nitrogen capacity can be expressed as lgCN = −5.59lgΛ − 12.41. With the increase in the Al2O3 content of slag, the nitrogen pickup amount of molten steel decreases and the nitrogen pickup rate decreases. The test with MgO = 7.5% showed the highest nitrogen pickup rate and the highest nitrogen pickup mass transfer coefficient, which were 0.21 × 10−4%/min and 1.97 × 10−4 cm/s, respectively. The test with Al2O3 = 7.5% in slag showed the lowest nitrogen pickup rate and the lowest nitrogen pickup mass transfer coefficient, which were 0.08 × 10−4%/min and 1.35 × 10−4 cm/s, respectively

Impact of Knowledge Spillover on Regional Club Convergence in China

Knowledge spillover theory introduces specialized knowledge and human capital accumulation into the production function, breaks through the limitations of traditional economic theory, and illustrates the continuous and permanent source and power of economic growth. This article attempts to study the “club phenomenon” of the uneven development of China’s regional economy from the perspective of knowledge spillover, using the Spatial Dubin Model (SDM) to process China’s provincial data from 1991 to 2015. Studies have shown that knowledge spillovers are conducive to narrowing the gap in the level of economic development between the eastern and central regions of China, but the gap in the level of economic development between the two regions is gradually widening, and there is a “club phenomenon”. Therefore, developing regional cooperation models and focusing on cultivating talents for innovation can improve China’s uneven regional economic development to a certain extent