The Classification Performance of a Three-Product Cyclone

Providing successful data collection in transmitter-initiated wireless sensor networks with mobile Sink (WSN-MS) scenarios is a primary goal of a myriad of critical applications in real world. Unfortunately, the problem of broken links which may occur during data transmission between a source node and a mobile Sink may cause inevitably incomplete data collection. To overcome this challenging issue, we propose in this paper a seamless handover mechanism performed on asynchronous duty cycled MAC protocol on the basis of neighborhood information. By measuring continuously the signal quality of ACKnowledgment messages of transmitted Data during a 1-hop communication, this mechanism allows the source node to continue transmitting data to the mobile Sink using a suitable neighbor node as relay in the case where the Sink node leaves the radio range in direction of that neighbor node. The asynchronous protocol XMAC (without handover) has been chosen as a basic protocol on which we designed our contribution named HXMAC (XMAC with handover). The later was implemented and evaluated using a powerful simulation tool. Experimental results based on the comparison between HXMAC and XMAC clearly showed that handover mechanism is a suitable technique to promote significantly reliability in WSN-MS data collection operation.     

Convective heat transfer characters of nanoparticle enhanced latent functionally thermal fluid

The latent heat of the microencapsulated phase change material (MPCM) increases the effective thermal capacity of latent functionally thermal fluid. However, researchers found that the heat transfer performance of such fluids was diminished due to the reduction of the low thermal conductivity of MPCM. For this reason, the nanoparticle enhanced latent functionally thermal fluids were formulated and the heat transfer behaviors of these fluids in a vertical circular tube at the laminar regime were conducted. The result showed that slurries containing 0.5% TiO₂ nanoparticles by mass and 5%–20% MPCM by mass exhibited improved heat transfer rates in comparison with the conventional latent functionally thermal fluid and that the enhancement increased with the increasing MPCM concentration and up to 18.9% of the dimensionless wall temperature was reduced. Supported by the National Natural Science Foundation of China (Grant No. 50076020)     

Preface

正In order to exchange the academic achievements on the impact dynamics in recent years,we are organizing the special issue on the Impact Dynamics of Structures/Materials.We have gladly collected five high-quality papers in this area,including"Atomic-level mechanism of spallation microvoid nucleation in medium entropy alloys under shock loading","Dynamic response of ultralight all-metallic sandwich panel with 3D tube cellular core to shallow-buried explosives","Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading","Mechanical behaviors of polycrystalline NiTi SMAs of various grain sizes under impact loading",and"Experimental investigation on the yield behavior of metal foam under shear-compression combined loading".     

焊缝结构微区材料力学性能研究

介绍三种对微区材料力学性能进行测试的方法,微拉伸试验、微剪切试验和维氏硬度试验,并分析其各自的优缺点。采用这三种方法对0Cr18Ni10Ti焊接接头不同区域材料进行力学性能测试,并对试验结果进行比较分析。研究指出,采用微小拉伸试样的微拉伸试验方法测定微区材料的力学性能更为准确可靠。     

Performance evaluation of half-duplex relay-based opportunistic cooperation diversity

Cooperative diversity is proposed as a means to improve the wireless transmission performance, which can effectively combat the wireless fading through sharing the antennas between source and relay nodes. In this paper, considering the practicability, we investigate the use of half-duplex relay, rather than full-duplex relay, for the opportunistic cooperation diversity. Two combining methods, namely selection diversity combining (SDC) and maximum ratio combining (MRC), are utilized for the implementation of...     

Investigation of thermal behavior on cylinder liner during its boring process

Research was conducted on the effect of cutting conditions on temperature rise of cylinder liner during cylinder-boring process. A finite element method (FEM) model was developed to confirm suitable cutting conditions by predicting the temperature distribution in a cylinder liner and thermal expansion of the cylinder liner. To analyze the temperature distribution in the cylinder liner during machining, the partition of the total heat generated during machining which flows into the cylinder liner has to be investigated. A method combining experiment with analysis, called an “inverse heat transfer method”, was used to estimate the heat percentage flowing to the cylinder liner in this paper. To capture the required data for the inverse heat transfer method, sets of dry and wet boring experiments were conducted to estimate the temperature distribution in the cylinder liner wall and the cutting force during machining. The influence of the cutting conditions (for example: cutting speed, feed rate, depth of cut, cutting fluid) on the cutting force and temperature distribution in a cylinder during machining was investigated, and the heat partition flowing to the workpiece under various cutting conditions (especially, under high-speed cutting, with a maximum cutting speed up to 900 m/min) was then determined. A three-dimensional FEM analysis model was developed to simulate the temperature distribution in the cylinder liner and thermal expansion of the cylinder liner during machining. Then, the suitable cutting conditions in cylinder boring were confirmed by FEM analysis. To investigate the influence of the air cooling on the temperature distribution in the cylinder liner after machining, the change of temperature distribution in the cylinder liner under air cooling was predicted.     

连续等径通道挤压三维有限元模拟

利用三维有限元模型研究等径通道挤压工艺不同挤压路线的连续挤压过程对变形组织均匀性的影响.通过两次挤压后试样横截面等效塑性应变分布比较发现, 采用工艺路线C连续挤压两次所得的试样横截面的等效塑性应变分布似乎最均匀.但是根据不同挤压路线连续两次挤压后横截面变形分布特点推测,若采用挤压路线BC经过多次挤压后(挤压次数为4的倍数),试样横截面上的变形分布将是最均匀的,即最有利于得到微观结构均匀的超细晶材料,这一推测被四次连续挤压有限元模拟结果所证实.     

海洋探测仪耐压壳体结构强度特性研究

参考标准设备及经典设计公式,根据设计要求研究非标设备耐压壳体结构强度,推导经典耐压壳体结构形式,采用修正弧长法进行屈曲失稳分析,考核了经典耐压壳体的强度及破坏形式。考虑实际耐压壳体结构的连接形式,分析封头的结构形式对耐压壳体强度特性的影响,研究表明,耐压壳体的稳定性、破坏形式及极限强度与封头和筒壁的重合度有关,增大重合度可有效提高耐压壳体的稳定性;重合度增大到一定程度时,破坏形式由失稳破坏变为屈服破坏;重合度和极限强度安全储备系数呈准线性关系,重合度越大,安全储备系数越高。     

基于单极调制的正弦脉宽幅度调制光伏逆变器死区时间的研究

针对死区时间对单极调制的正弦脉宽幅度调制(SPWM)光伏逆变器输出电压波形的影响,根据开关管的开关特性,提出了在正弦基波换相处设置死区时间的方法,并对死区时间的计算给出理论推导.最后通过Matlab/simulink仿真验证,该方法可以获得良好的输出电压波形,有效地降低输出电压波形失真度.     

国外珠宝款式流行走向

众所周知，由于文化习俗，消费能力以及意识形态上的差异，国内外珠宝在款式，材质上有很大的不同，现今国内珠宝主流市依然是素金、镶嵌类产品的天下，而在镶嵌类产品中，钻石产品具有垄断性的优势地位。