Efficient one pot synthesis of chitosan-induced gold nanoparticles by microwave irradiation

An efficient and rapid method for the preparation of gold nanoparticles (AuNPs) within a few minutes has been developed by direct microwave irradiation of HAuCl₄ and chitosan mixed solution in one pot. Herein, chitosan molecules acted as both the reducing and stabilizing agent for the preparation of AuNPs. The obtained AuNPs have different shapes, such as the spherical nanoparticles, triangular nanoplates and nanorods, which were characterized by ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FTIR). Additionally, the results showed that microwave power could affect the required time for preparing the AuNPs arising from the distinction of heating rate, and long irradiation time was favorable for complete reduction of HAuCl₄ when a low microwave power was applied.     

超声电沉积制备Cu-In合金膜

采用超声电沉积-热处理两步法和超声共沉积一步法在钼基底上制备了致密的Cu-In合金薄膜。分别用SEM,EDS和XRD分析了Cu/In双层膜以及Cu-In合金膜的表面形貌、成分及相组成。结果表明:采用不同的电沉积工艺参数可以调节合金膜的Cu/In比率;超声电沉积可以得到晶粒细小、均匀致密的Cu,In以及Cu-In合金薄膜;两步法中超声电沉积得到的双层膜为CuIn和Cu或In相,经过热处理后转变为Cu11In9和Cu或In相;一步法超声共沉积得到的合金膜主要为CuIn相,根据Cu/In比率的不同,还会含有少量的Cu11In9或In相。     

RM1070导航雷达调制器电路原理分析

调制器是收发机中的一个重要的组成部分,本文对调制器电路原理进行了详细分析。实践证明,深入理解调制器电路原理对雷达的故障检修是十分有益的。     

Effects of transition metal (Cu,Zn, Mn) doped on leakage current and ferroelectric properties of BiFeO<Subscript>3</Subscript> thin films

BiFeO₃ (BFO) and transition metal (Cu, Zn, Mn) doped BFO thin films were successfully fabricated on indium tin oxide (ITO)/glass substrate using sol–gel process, spin coating and layer by layer technique. Compared to the pure BFO thin film, improved ferroelectric and leakage current properties were observed in the transition metal doped BFO thin films. The transition metal (Cu, Zn, Mn) doped BFO thin films have varying degrees of lower leakage current compared with the pure BFO film. The substitution of Cu and Zn increase the remnant polarization of BFO thin films. The values of remnant polarization (2Pr) were 120.6 and 126.7 μC/cm² at 933 kV/cm for Cu-doped and Zn-doped BFO thin film, respectively.     

基于IAHP与模糊重心(矩)的制造执行系统综合业绩分析与评价模型

制造执行系统在生产管理信息系统与设备控制系统之间构筑了一座桥梁，连接了企业上层管理与下层控制之间的信息断层。为了提高制造执行系统的整体执行性能，需要对各单元的生产业绩进行分析与评价。提出了分析与评价指标体系并重点阐述了改进的层次分析法及基于模糊重心和模糊重心矩的综合评价理论在制造执行系统业绩分析与评价中的应用。     

Mo–V–M–O (M = Te, W, Fe, Ga) catalysts for selective ammoxidation of propane

We report the incorporation of Ga, Fe, and W, well-known activity and selectivity promoters in lower alkane activation, into Te-free Mo–V–O M1 phase in order to improve its stability under propane ammoxidation conditions. The Mo–V–M–O (M = W, Fe, Ga) M1 phases displayed improved stability as compared to the parent Mo–V–Te–O M1 phase due to higher Tammann temperatures of M oxides and activity for direct conversion of propane to propene and acrylonitrile.     

新型直动式压电伺服阀

提出一种新型压电驱动单级电液伺服阀,其特点是可以提供比传统电磁式电液伺服阀更高的频宽与分辨率,而且结构紧凑、抗污染能力强。该阀采用大行程的压电叠堆(积层式压电驱动器)作为驱动元件直接驱动滑阀,通过基于弹性变形原理的弹性板机构,结合电阻应变式微位移传感器,实现机构及检测一体化。应用有限元法对弹性板机构进行分析优化,试制了直动式压电伺服阀样机并对样机进行了试验研究,得出该阀的频宽约为1 kHz。新型伺服阀可以应用于振动试验台、疲劳试验台及需要快速反应的流体控制系统中,提高系统的响应特性。     

Traffic Prediction Using Multifaceted Techniques: A Survey

Road transportation is the largest and complex nonlinear entity of the traffic management system. Accurate prediction of traffic-related information is necessary for an effective functioning of Intelligent Transportation System (ITS). It is still a challenge for the departments of transportation to choose an appropriate prediction technique for the ITS applications. That is, a user must be able to utilize the disseminated information effectively by the forecasting models. This paper provides a detailed survey of the latest forecasting technologies and contributes to understand the key concept behind the prediction approaches. To provide guidelines to the decision-maker, this paper reviews multifaceted techniques developed by various authors for traffic prediction. We start classifying each technique into four categories namely, Machine Learning (ML), Computational Intelligence (CI), Deep Learning (DL), and hybrid algorithms. Many have conducted survey using model-driven or data-driven methods. We are the first to explore the area of traffic prediction based on the advances in multifaceted techniques proposing algorithmic approaches for key traffic characteristics in the forecasting process. The role of dependent factors in the prediction are analyzed thoroughly. We have analyzed each algorithm chronologically based on various traffic traits. The approaches are summarized based on the rational usage and performance of each technique. The analysis led to several research queries, and the appropriate  responses are provided based on our detail survey. Finally, it is confirmed that currently, CI-MLs and DL hybrid techniques outperforms the rest in the field of traffic prediction. Ultimately suggested open challenges and future direction to explore the capability of DL and hybrid techniques further in the field of traffic prediction. 

     

离心风机振动噪声及压力脉动实验研究

利用传声器、加速度计、微型精密压力传感器对离心风机噪声、管道振动及压力脉动进行测量分析。结果表明，在风机噪声、管道振动、压力脉动频谱中与叶轮转动相关的离散分量明显，旋转频率分量最大；离散频率处噪声、振动与压力脉动相干函数值在0.5以上，而宽频分量处的相干函数值较小；管道内强烈压力脉动主要在距离风机出口5D(D为管道水力直径)的范围内，强度与参考动压ρv2b/2（ρ为流体密度，v为体积速度）相当；在10D以后，管内流场趋于均匀，压力脉动值约为参考动压的20%;压力脉动频谱中旋转频率分量最为明显，其幅度在风机出口2D~4D附近达到最大，为参考动压的25%左右。     

新型环形内燃室顶燃式热风炉燃烧过程模拟及分析

针对内燃式热风炉隔墙温差大的缺点,设计了一种新型环形内燃室顶燃式热风炉,采用Fluent软件建立了这种新型顶燃式热风炉环形燃烧室流动、传热、燃烧及辐射三维数学模型,对不同内燃室高度下的热风炉的燃烧过程进行了数值计算,并对其空、煤气燃烧过程中燃烧室内的流场、浓度场、温度场及火焰形状进行了分析.结果表明:内燃室高度的增加可...