航空底片测试仪的恒张力数字控制系统研制

在航空底片测试仪的运动过程中,底片张力的变化对底片的位移和定位精度影响很大,从而导致测试结果的稳定性.在对测试仪传动机构的运动学和动力学分析的基础上,建立了全数字闭环控制模型.为了实现张力的实时采样和控制,采用数字信号处理技术(DSP)控制底片在运动过程中的张力,使张力趋于设定的最佳值.使得测试仪获取稳定的、真实的图像数据,为正确测评航空感光胶片成像质量提供了基础.实验结果表明底片平均移动速度最高可达到23m/min;张力设定范围是F_min=0N,F_max=30N;张力变化控制量为ΔF=±0.05N;重复定位精度为±10μm;满足了设计要求.     

汽车尾气温差发电装置中热电器件的试验研究

为了利用热电器件回收汽车尾气的废热进行发电,构建了一个可模拟汽车尾气温差发电装置的热电器件测试平台,测试了不同热源温度、冷源温度、安装压力以及相同冷热源温差而不同冷热源温度下国产某型Bi2Te3基低温热电器件的输出性能。结果表明,单个热电器件的输出性能与其安装压力和冷热源温差成正比,在相同冷热源温差条件下可适当降低冷源温度以提高其性能;随着冷热源温差增大,热电器件的最大功率所对应的输出电流明显增大;利用汽车发动机自身冷却系统中约90℃的冷却水对汽车尾气温差发电装置进行冷却时,当热端温度达到350℃的最大耐温值,安装压力大于57kPa时,单个热电器件的最大输出功率在3W以上。最后,基于该热电器件提出了汽车尾气温差发电装置的优化设计策略及其工作条件。     

柔性制造系统切削稳定性在线监测技术的研究

主要讨论柔性制造系统(FMS)切削稳定性的在线监测方法,在研究FMS切削过程中振动信号变化规律的基础上^[1],提出了用μ_a=E(a)/F(a)作为FMS切削稳定性的监测参数,并进行了理论分析和试验验证.     

铌硼镧锌系统玻璃的研究

根据X射线、差热分析与扫描电镜等测定数据,获得了以下实验结果:1)Nb₂O₅的引入显著扩展了硼镧锌系统玻璃生成范围。其方向主要出现在B₂O₃含量降低或La₂O₃含量增加的区域Nb₂O₅形成了玻璃网络。     

基于区域分割的自适应反锐化掩模算法

针对线性反锐化掩模法的缺点,提出一种基于区域分割的自适应反锐化掩模法,利用像素局部方差将输入图像划分为平滑区、中等对比度区和高对比度区,根据像素(x,y)所属的区域类型,自适应确定其局部灰阶变化率增益系数α(x,y)及期望的输出局部灰阶变化率H_d(x,y),并导出增强系数K(x,y)。对一幅胸片图像进行处理,并与其它几种反锐化掩模法的处理结果进行比较,结果显示该方法获得较好的边缘增强效果,且有较强的噪声抑制能力。     

工作波长短于10nm的软X射线多层膜

本文对工作波长短于10nm的软X射线多层膜正入射反射镜的国内外现状作了简单的介绍和分析,给出选择多层膜材料的一些原则,并结合本组情况选择了Ru/B₄C、Rh/B₄C和MO/B₄C三种材料组,在波长8.0nm附近设计并计算出多层膜的结构和反射率等性能参数.     

光折变晶体两波耦合增益系数强度特性理论研究

对两中心模型光折变晶体两波耦合增益系数Γ,总的有效陷阱密度N_eff和强度特性因子η(I)的强度特性进行了理论研究。结果显示在两中心模型的光折变晶体中,Γ,N_eff和η(I)有着复杂的特性。当S_Dγ_T/S_Tγ_D小时,对于A类和B类两中心晶体,N_eff随强度的增加而增加最终趋于饱和,当S_Dγ_T/S_Tγ_D大时,对于A类晶体N_eff增加到一个最大值后稍有减少,而对于B类晶体,N_eff增加到最大值后然而有较大的减少。不同类型晶体增益系数Γ有着不同的强度特性是由于晶体中有着不同的能级结构。     

ZnO薄膜非线性光学特性的实验研究

利用金属有机化学气相沉积(MOCVD)技术在蓝宝石衬底上生长一层高质量的ZnO薄膜。为了考察沉积温度对样品的非线性特性的影响,在200~500 ℃生长了一系列ZnO薄膜。用X射线衍射谱(XRD)及扫描电镜(SEM)对样品结构进行了评价。以Nd:YAG激光器输出的1.06 μm的激光为基频光,对ZnO薄膜样品的二阶及三阶非线性光学特性进行了实验研究。实验发现,对于250 ℃沉积温度的样品有较强的非线性效应,实验测得的二阶非线性极化张量 χ ⁽²⁾_ZZZ=9.2 pm/V, 三阶有效非线性系数χ⁽³⁾=5.28×10^－20 m²/V²。     

铝合金搅拌摩擦焊液冷流道承压力学模型

为了实现液冷组件的可靠性设计,并且缩短液冷流道结构的设计周期,文中在通过力学仿真计算获得大量仿真数据的基础上,探索了流道承压共性规律,明确了液冷流道承压最大应力响应的影响因素及影响规律。结果表明,搅拌摩擦焊液冷流道内部的最大等效应力与盖板厚度呈反比,与盖板承压宽度的平方呈正比,与内压呈正比,在此基础上,建立了液冷流道承压力学模型 σ = KPL ² H ^-1,其中,对于铝合金液冷组件,K=0. 243 mm^-1。该承压力学模型为液冷组件提供了力学设计依据,根据液冷组件流道内压可以快速明确其几何尺寸,大大提高了设计效率,且广泛适用于采用其他焊接方法制造的同结构类型的液冷组件。     

寒区高边坡机场坡顶土体振动响应研究

为解决寒区高填方机场坡顶土体安全问题,通过引入土体并联振动模型和快速傅里叶变换（fast Fourier transform, 简称FFT）,分析了振动台试验中冻结土样振动响应在时域和频域内的变化规律,提出了基于响应频率的冻结土样动力稳定性分析方法。研究表明：冻结土样在融化过程中的加速度增长比R_a、频率和频率增长比R_f均明显变大,但加速度幅值变化规律不明显;土样含水率越高,融化时间越短,R_f越大,完全融化后的响应频率值越大,但对加速度放大系数影响不大;在高温冻结阶段,R_f出现突变但R_a变化不显著,表明在频域中分析冻结土样振动响应变化比时域分析中灵敏度更高。振动台试验结果验证了土体振动并联模型的可靠性,对寒区高填方机场坡顶土体安全监测具有一定参考价值。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...