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Microstructure evolution of polycrystalline nickel based superalloy C1023 casting was investigated by comparing as cast superalloy and heat treated superalloy in the paper. Influences of strengtheners and carbides on the tensile behaviors of heat treated superalloy at different temperatures (20 °C, 650 °C, and 850 °C) were studied. Resulting data from deep corrosion suggested that growth mode of scripted carbide included nucleation on the vertex of blocky carbonitride, expansion of dendrite arm in C-rich area, and enlargement of dendrite cap. Decomposition of MC carbide generated numerous octahedral M23C6 carbide as well as nanoscale Cr-Mo-rich nuclei. Diffusion of Mo from γ to precipitates such as γ', MC, and M23C6, occurred during the heat treatment while irregular γ' (4 nm–500 nm) transformed into cuboidal particles. At 650 °C, no significant deterioration of tensile strength was found while plastic deformation ability of γ base was improved. Oxidation of grain boundaries (GBs) dominated the crack behavior of the superalloy at 850 °C.

A generalized framework consisting of a stochastic model, a responsive control method, and typical scenarios using vehicle-to-pedestrian (V2P) communication is proposed to improve pedestrian safety. The proposed stochastic model formulates various effects of uncertainties in a V2P communication system. The responsive control method is used to improve pedestrian safety under V2P communication conditions. Results show that adopting only Bluetooth or Wi-Fi (wireless local area network) technology, which has a high establishment time, is not sufficient for V2P communication, whereas dedicated short-range communication (DSRC) featuring low latencies meets requirements. A case study in the field was conducted to evaluate the feasibility of responsive control; it was concluded that with the use of the proposed model and the responsive control method, Bluetooth technology combined with DSRC could be workable for active pedestrian protection.

Intelligent Transportation System (ITS) is recognized as one of the most effective means to solve the problem of modern traffic, and connected vehicle technology is a key link in the intelligent transportation system, which plays a Decisive role in the impact of intelligent transportation. This paper introduces the architecture of connected vehicle which based on DSRC technology, the operating mechanism, and its application. Finally, the connected vehicle platform we have been building is introduced, and it needs further research.

Traffic state estimation is important for active traffic planning, management, and control. By utilizing traffic status over time and space, a key theoretical analysis tool, i.e., shockwave theory, can be adopted as efficient tools to solve bottleneck or congestion problems. Two methods, who are fixed point observations and mobile probe vehicle observations, are typical methods and popular in traffic analytical agencies and projects. But both of them has their problems and new insights are needed for current proactive and online traffic implementations. In this paper, a dynamic traffic shockwave estimation method with both high temporal resolution and high spatial resolution is proposed based on integrating vehicle detecting system data from fixed loop detectors and trajectory data from probe vehicles in a connected vehicle environment. The proposed method was validated in a prevailing dataset. Results showed that the proposed method combined the advantages of mobile and fixed data. As a result, the proposed method is effective in improving the spatial and temporal resolution of the shockwave estimation in the considered general scenario.

Traffic safety has been one of the most primary social problems puzzling big cities over the world. It is widely believed that connected vehicle technology will tackle this problem. To achieve that, we installed RSE (Road Side Equipment) in urban road environment to communicate with OBE (On Board Equipment) through DSRC (dedicated short-range communication) to organize a DSRC network system. However, as a fundamental communication device, RSE may lose connections, which will have impacts on the quality of collected data and finally this might lead to failures of traffic applications. Therefore, it is necessary to validate the connection status of DSRC network environment. In this paper, based on analyzing non-continuous DSRC network system, a field test method for connected vehicle technology (CVT) application is proposed to verify whether such a network system is in good condition to ensure normal usages of traffic applications or not. Then, a case study in the field is conducted to evaluate the validities of some important parameters (i.e., latency, distance, and speed). We draw a conclusion that the network system was available for CVT application; but was desired to be improved.

The influence of 1.3 wt.% Gd on microstructure and mechanical properties of cast and hot-extruded ZK60 (Mg–6Zn–0.4Zr) alloy was studied in different conditions, including as-cast, cast-T4, cast-T6 and extruded-T5 and extruded-T6 at the extrusion temperatures of 623, 673 and 723 K. The results show that the addition of Gd leads to a considerable reduction of the age-hardening response and a small decrease of tensile yield strength (TYS) and ultimate tensile strength (UTS) in cast-T6 and extruded-T5 conditions, owing to the formation of Mg–Zn–Gd intermetallic compound which consumes some of Zn atoms in the matrix. However, the grain refinement caused by the addition of Gd is remarkable, which compensates partly for the loss of TYS and UTS due to the consumption of Zn in the matrix and improves the elongation of the alloy, especially at the elevated temperature.

In order to increase the casting quality and material plasticity of hypoeutectic Al–Si alloys, the effects of melt thermal treatment on the solidification structure of the A356 alloy were analyzed. Unlike the conventional melt addition treatment, no refinements are required during this novel processing. The structural characteristics and mechanical properties (plasticity and strength) were demonstrated. Results of quantitative metallorgraphic analysis showed that the primary dendrite size obviously reduces and the dendrite grains change into equiaxed ones. However, the secondary dendrite arm spacing changes little. Experimental results show that there is an optimal cooling rate range for thermal treatment, in which a maximum microstructure refining effect can be obtained. By the optimized parameters obtained with orthogonal experiments, the elongation ratio of the castings increases by 46.2% and the tensile strength by 8.6%. These results are explained by means of microheterogeneous melt theory, which is a result of the multiplication of the nuclei in the melt thermal treating procedure.

In order to obtain better mechanical properties, fine particles in several micron or submicron diameter are used as reinforcement to reduce stress concentration which are usually induced by larger particles. Zn–22% Al matrix composites with fine alumina particulate reinforcement are fabricated by high intensity ultrasonic treatment. The particulate sizes are chosen with the minimum 0.5 μm. Comparing the height change of composite samples before and after remelted, which have been degassed with semisolid compression, the relation between apparent viscosity and reinforcement diameter is obtained. Experimental results show that there is no interface reactive product involved in the apparent viscosity change. With smaller particulate size, the viscous force is enhanced. That is the dominating reason for the composite melt apparent viscosity increment. An additional reason is the gas introduced with the particulates.

A new refining method—melt thermal treatment without additive to melt is studied in this paper. Microstructure analysis and property evaluation of hypoeutectic Al–Si alloys treated with this method show that the solidification microstructure can be refined significantly with a considerable increase in elongation ratio and strength. Effects such as cooling rate, holding time and alloy composition on the solidification microstructure and mechanical properties have been evaluated. It is shown that the strengthening and toughening effects on the treated samples vary with alloy composition. The property increment of the alloy rich of iron is relatively more remarkable than those rich of Cu or Mg element. Specifically, the structure of the low temperature melt is identified as a primary factor, on which the solidification structure of the treated melt is dependent.