矿井中频感应通信系统研究

分析与研究矿井中频感应通信系统 ,并提出了一种新型的矿井中频数字感应通信系统。这种系统采用连续可变斜率增量调制 (CVSD)来实现语音信号的编码、GFM调制解调方式、FDMA、PLL频率合成器技术。本系统具有通话质量好、设备简单、抗衰减能力强等特点 ,适于矿井通信。     

高纯四溴双酚A双(2,3-二溴丙基)醚合成新工艺

研究了合成阻燃剂四溴双酚A双(2，3-二溴丙基)醚的新工艺，特点是通过加入表面活性剂TABS、催化剂SB和表面活性剂A的方法，提高产品纯度和降低游离酸的含量，成品的炭化温度为295℃，纯度大于95％。     

cdSe_xTe_(1-x)薄膜电极光溶解性能的研究

用循环伏安法对半导体Cdse_xTe_(1-x)薄膜电池的光溶解性能进行了研究。在1mol/L KCl溶液中测量光溶解产物的阴极还原特性,考察了在多硫化钠,多硫化钾及铁氰化钾溶液中的光腐蚀行为。用此方法还研究了薄膜电极表面的光刻蚀过程和pH的影响,并用X射线光电子能谱分析光刻进行不同时间后,电极表面发生的变化。     

Multidisciplinary design optimization of adaptive wing leading edge

Adaptive wing can significantly enhance aircraft aerodynamic performance, which refers to aerodynamic and structural opti-mization designs. This paper introduces a two-step approach to solve the interrelated problems of the adaptive leading edge. In the first step, the procedure of airfoil optimization is carried out with an initial configuration of NACA 0006. On the basis of the combination of design of experiment (DOE), response surface method (RSM) and genetic algorithm (GA), an adaptive air-foil can be obtained whose lift-to-drag ratio is larger than the baseline airfoil’s at the given angle of attack and subsonic speed.The next step is to design a compliant structure to achieve the target airfoil shape, which is the optimization result of the previous step. In order to minimize the deviation of the deformed shape from the target shape, the load path representation topology method is presented. This method is developed by way of GA, with size and shape optimization incorporated in it simul-taneously. Finally, a comparison study with the Solid Isotropic Material with Penalization (SIMP) method in Altair OptiStruct is conducted, and the results demonstrate the validity and effectiveness of the proposed approach.     

Low-frequency wide-band hybrid energy harvester based on piezoelectric and triboelectric mechanism

Recently,hybrid energy harvester has been considered as an attractive potential approach to response the worldwide energy crisis due to the combination of advantages from different harvesting mechanism.In this paper,a novel low-frequency wide-band hybrid energy harvester based on piezoelectric and triboelectric mechanism is presented and systematically studied including structural design,fabrication process,working principle simulation and measurement.With a vibrational excitation,the polyvinylidene fluoride(PVDF) cantilevers will vibrate and impact the polydimethylsiloxane(PDMS) film on the substrate,producing a piezoelectric output as well as a triboelectric output.The structural parameters of each cantilever are optimized using finite element simulation,and the well-designed PVDF cantilevers with controllable PDMS mass not only reduce the device working frequency but also enlarge the bandwidth.Under a sweep-frequency test,three voltage peaks induced by the piezoelectric part are observed at 15,32.5 and 47.5 Hz,with the value of 320,288 and 264 mV,respectively.With the combined triboelectric part,a 20 V peak-peak voltage is generated at 15 Hz.The electrical driving ability of this hybrid energy harvester also has been demonstrated by lighting up a commercial light emitting diode(LED).     

Modeling deterministic echo state network with loop reservoir

Echo state network (ESN),which efficiently models nonlinear dynamic systems,has been proposed as a special form of recurrent neural network.However,most of the proposed ESNs consist of complex reservoi...     

基于SVD、DCT和RSA加密数字水印算法研究

提出了一种基于SVD、DCT、RSA加密数字水印算法,该方法是将载体文档图像做8＊8块的DCT变换,水印图像进行了Arnold处理,将水印图像嵌入到变换的SVD正定矩阵中,修改中频域频谱系数,同时对文档使用RSA算法进行加密,含有水印的图像经IDCT变换存成嵌入水印的图像。通过提取变换域的SVD,提取数字水印,经过RSA算法加密后解密该文档,在经过猫脸逆变换处理得到数字水印图像,水印图像的提取IDCT实验结果表明,本文算法具有安全性高、鲁棒性强以及嵌入水印较好的视觉隐蔽特性、算法处理速度快等特点。     

自行车椭圆链轮传动机构的分析设计

分析了自行车的连续圆周运动不能使脚蹬力均匀变化的特性,对传统自行车的传动机构中存在的问题进行了改进。本文基于人机工程学原理用椭圆链轮代替主动圆链轮作为自行车的不等速传动装置,对该传动机构进行了优化,克服了自行车传动过程中出现的缺点,能最大限度的发挥人体结构的用力功能,从而推广了自行车的新应用。     

提高机械基础课教学效果的实践与探索

机械基础课因其内容通俗、知识面覆盖广的特点,对此本文通过多年来的教学实践,在如何有效组织本课程的教学,提高教学质量和教学效果,既能使学生轻松而又系统地掌握知识点,又能激发学生主动学习机械类相关专业知识的积极性进行了深入探索和实践,从而确定了较为合理的教学手段和方法。