基于MEMS技术的新型变形反射镜

基于MEMS技术体硅工艺,提出一种新型大有效面积的连续变形反射镜的设计制造方法。依工艺流程中的实际情况与结果,分析了在制造过程中遇到的大面积腔体深腐蚀中凸角腐蚀和键合中小空隙粘合等关键问题,设计实施了T形补偿角、延长驱动线等解决方案。用此方法制造出有效反射面积30mm×30mm,最大变形量1.2μm,49驱动电极的新型变形反射镜。10-200V电压范围内得到的该变形反射镜镜面变形数据与模拟结果具有很好的一致性。     

Optical zoom module based on two deformable mirrors for mobile device applications

In recent years, optical zoom functionality in mobile devices has been studied. Traditional zoom systems use motors to change separation of lenses to achieve the zoom function, but these systems result in long total length and high power consumption, which are not suitable for mobile devices. Adopting micromachined polymer deformable mirrors in zoom systems has the potential to reduce thickness and chromatic aberration. In this paper, we propose a 2× continuous optical zoom system with five-megapixel image sensors by using two deformable mirrors. In our design, the thickness of the zoom system is about 11 mm. The effective focal length ranges from 4.7 mm at a field angle of 52° to 9.4 mm. The f-number is 4.4 and 6.4 at the wide-angle and telephoto end, respectively.     

Uncertainty in probabilistic risk assessment

Dealing with uncertainty is an important and difficult aspect of analyses for complex systems. Such systems involve many uncertainties, and assessing probabilities to represent these uncertainties is itself a complex undertaking utilizing a variety of information sources. At a very basic level, uncertainty is uncertainty, and attempting to distinguish between ‘types of uncertainty’ is questionable. At a practical level, on the other hand, a close look at such distinctions suggests that they are driven by important modelling issues related to model structuring, probability assessment, information gathering, and sensitivity analysis. Anything that brings more attention to these issues should improve the state of the art. However, I would prefer to attack the issues directly instead of working indirectly through the notion of ‘types of uncertainty.’     

基于可变形空腔的起落架舱体噪声抑制研究EI北大核心CSCD

提出了一种基于可变形空腔的起落架舱体结构,通过机械装置调节舱体底板及后壁倾斜角度,不需要额外增加舱体体积,使用声学有限元法探讨了该结构在低马赫数下的噪声抑制效果。研究发现:随着舱体后壁倾斜角度的增大,舱体内部及外部的噪声明显减小,同时模态频率逐渐增大,有助于避免舱体结构发生共振破坏;舱体后壁倾斜一个较小的角度就能有效地改善内部的声反射环境,进而抑制舱体内部的高频模态噪声、总声压级。当后壁倾斜角度大于某个临界值时,继续增大倾斜角度对于舱体内部高频模态噪声以及总声压级的抑制效果不再明显,在当前的仿真条件下,舱体后壁最佳倾斜角度范围为10°~16°。     

基于MCM的不确定度评定软件开发

蒙特卡洛法(MCM)是基于对输入量的概率分布进行统计模拟的一种不确定度评定方法,主要应用于不适合使用GUM法评定测量不确定度的场合,并可对GUM法评定结果进行验证。提出一种用VB6实现自适应蒙特卡洛试验的软件实现方法,根据用户录入的输入量参数生成符合相应分布规律的伪随机数,代入用户录入的测量模型,得到一组输出量的蒙特卡洛试验数据,对这些数据进行统计处理得到输出量的测量不确定度评定结果及其概率密度分布曲线。该文简要介绍了软件的系统架构、测量不确定评定中常见分布的伪随机数算法及统计试验关键算法。     

Full Eulerian deformable solid-fluid interaction scheme based on building-cube method for large-scale parallel computing

We propose a full Eulerian incompressible solid-fluid interaction scheme capable of achieving high parallel efficiency and easily generating meshes for complex solid geometries. While good scalability of a full Eulerian solid-fluid interaction formulation has been reported by Sugiyama et al, their analysis was carried out using uniform Cartesian mesh and an artificial compressibility method. Typically, it is more challenging to achieve good scalability for hierarchical Cartesian meshes and a fully incompressible formulation. In addition, the conventional full Eulerian methods require a large computational cost to resolve complex solid geometries due to the usage of uniform Cartesian meshes. In an attempt to overcome the aforementioned issues, we employ the building-cube method, where the computational domain is divided into cubic regions called cubes. Each cube is divided at equal intervals, the same number of cubes is assigned to each core, and the spatial loop processing is executed for each cube. The numerical method is verified by computing five numerical examples. In the weak scaling test, the parallel efficiency at 32768 cores with 32 cores as a reference is 93.6%. In the strong scaling test, the parallel efficiency at 32768 cores with 128 cores as a reference is 70.2%.     

Inverse geometry heat transfer problem based on a radial basis functions geometry representation

We present a methodology for solving a non‐linear inverse geometry heat transfer problem where the observations are temperature measurements at points inside the object and the unknown is the geometry of the volume where the problem is defined. The representation of the geometry is based on radial basis functions (RBFs) and the non‐linear inverse problem is solved using the iteratively regularized Gauss–Newton method. In our work, we consider not only the problem with no geometry restrictions but also the bound‐constrained problem. The methodology is used for the industrial application of estimating the location of the 1150°C isotherm in a blast furnace hearth, based on measurements of the thermocouples located inside it. We validate the solution of the algorithm against simulated measurements with different levels of noise and study its behaviour on different regularization matrices. Finally, we analyse the error behaviour of the solution. Copyright © 2005 John Wiley & Sons, Ltd.     

Uncertainty assessment of the road safety index

Composite indicators aggregate domain-specific information in one index, on the basis of which countries can be assigned a relative ranking. Recently, the road safety community got convinced of the policy supporting role of indicators in terms of benchmarking, target setting and selection of measures. However, combining the information of a set of relevant risk indicators in one index presenting the whole picture turns out to be very challenging. In particular, the rank of a country can be largely influenced by the methodological choices made during the composite indicator building process. Decisions concerning the selection of indicators, the normalisation of the indicator values, the weighting of indicators and the way of aggregating can influence the final ranking. In this research, it is shown that the road safety ranking of countries differs significantly according to the selected weighting method, the expert choice and the set of indicators. From these three input factors, the selection of the set of indicators is most influential. A well considered selection of indicators will therefore establish the largest reduction in ranking uncertainty. With a set of appropriate indicators, the proposed framework reveals the major sources of uncertainty in the creation of a composite road safety indicator.     

The formation of features for recognizing complex images based on stochastic geometry

The theory of obtaining the features of pattern recognition based on stochastic geometry and having a three-functional structure (triplet features) is presented. The effectiveness of the proposed method of forming features for recognizing complex-structured and semantically saturated images is proved. A practical example of the formation of features for images from the area of medical diagnostics is considered. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 56–61, February, 2008.     

基于变形离散元法的重力坝地震开裂分析

考虑脆性材料Ⅰ型和Ⅱ型复合断裂情况,基于渐进破坏理论建立了混凝土损伤破坏模型,提出一种损伤开裂模型与变形离散单元法耦合的分析方法。模拟了Koyna坝在强烈地震作用下的渐进破坏过程,通过与室内模型试验及其他方法所得结果的对比,验证了该方法的可靠性和正确性。研究表明：坝体初始裂缝是由地震拉应力集中所致,坝体开裂后,裂缝周围应力重新分布,但缝端仍存在拉应力集中现象,导致裂缝不断扩张;裂缝发展可分4个阶段;裂缝贯通后,坝头与底部剧烈错动,坝体动能减小,摩擦功急剧增加。     

Stroke amplifier for deformable mirrors

We demonstrate a simple optical configuration that amplifies the usable stroke of a deformable mirror. By arranging for the wavefront to traverse the deformable mirror more than once, we correct it more than once. The experimental implementation of the idea demonstrates a doubling of 2.0 and 2.04 by two different means.     

基于三角形几何相似性的图像配准与拼接

介绍了一种基于三角形几何相似性的图像配准方法.提取两幅待拼接图像的特征点,将每幅图像各自的重叠区域内或图像内容复杂情况下的选定区域内的特征点任意组合为三角形,得到分别对应于每一幅图像的三角形集合.然后根据定义的新的三角形表示方法,包括最大角方向和最小角方向,在两组三角形集合内层层筛选任意组合的三角形对,最终找到其中的匹配三角形对,即相似三角形对,从而找到匹配的点对.最后计算图像间变换矩阵,对图像进行拼接,得到了一张具有更宽视野的无缝拼接图.该方法只与特征点间相互几何位置有关,所以对两幅图像间的灰度差异、任意的旋转、缩放等都表现了很强的鲁棒性.     

基于变形模型的心血管三维运动跟踪

提出一种心血管造影图像序列的三维运动跟踪方法。按照自顶向下的方式,采用三维变形模型,通过使适当的能量函数最小,表示血管骨架的曲线直接在三维空间中变形,完成血管骨架序列的三维重建。该方法将序列图像中血管的二维中心线提取、三维重建和运动跟踪集成到一个框架中完成,提高了重建精度和运算速度。     

平面度误差粒子群算法评定的不确定度评估

形状误差智能评定采用概率化随机搜索,评定结果存在分散性,针对此问题提出一种不确定度评估方法。以平面度误差粒子群算法评定为例,根据智能评定结果概率分布特性,采用β分布统示法拟合其概率分布,并对平面度误差进行区间估计,最后选取仿真平面测量数据进行不确定度评估实验。结果表明,样本个数NS=100、截取百分位数Qp=20时,估计区间能够有效包容平面度误差值,且平均宽度较小,验证基于β分布统示法的智能评定不确定度评估可行性。     

Uncertainty in cost-benefit analysis based on referendum contingent valuation

Using contingent valuation methods (CVM) is increasingly common in project analysis. Referendum-type questions are thought to be easier to answer than the open-ended variety, but there is a downside: econometric techniques must be applied to the referendum data to infer the mean or median willingness to pay (WTP) of the sample and, thus, of the population of potential beneficiaries. This is not just a technical point as is demonstrated with data from a referendum CV study of a sewage and wastewater treatment project in Brazil. A factor of 4 separates lowest from highest central tendency estimates, ignoring the outlier that is 14 times larger than the largest of the other figures. This is ample variation to make a difference in the cost-benefit analysis. Analysts using referendum CV must be sensitive to the problems they buy into, and must decide how to deal with the uncertainty in the results.     

Self-healing,elastic and deformable novel composite phase change polymer based on thermoplastic elastomer SEBS for wearable devices

Journal of Materials Science - Form-stable composite phase change materials (C-PCMs) prepared by microencapsulation method and porous matrix adsorption method need for compression molding after...     

基于微分几何的非完整移动操作臂解耦控制

针对在非完整移动操作臂(NMM)系统协调控制中传统解耦线性化方法所带来的局部线性化及近似线性化等问题,采用微分几何方法,通过适当的微分同胚和非线性反馈实现NMM系统多输入多输出非线性解耦控制,将多变量、强耦合、非线性的复杂系统精确转换为线性解耦系统.由NMM系统的状态方程建立其仿射非线性系统模型,并进行解耦条件验证,通...     

Uncertainty budget for a whole body counter in the scan geometry and computer simulation of the calibration phantoms

At the Austrian Research Centers Seibersdorf (ARCS), a whole body counter (WBC) in the scan geometry is used to perform routine measurements for the determination of radioactive intake of workers. The calibration of the WBC is made using bottle phantoms with a homogeneous activity distribution. The same calibration procedures have been simulated using Monte Carlo N-Particle (MCNP) code and FLUKA and the results of the full energy peak efficiencies for eight energies and five phantoms have been compared with the experimental results. The deviation between experiment and simulation results is within 10%. Furthermore, uncertainty budget evaluations have been performed to find out which parameters make substantial contributions to these differences. Therefore, statistical errors of the Monte Carlo simulation, uncertainties in the cross section tables and differences due to geometrical considerations have been taken into account. Comparisons between these results and the one with inhomogeneous distribution, for which the activity is concentrated only in certain parts of the body (such as head, lung, arms and legs), have been performed. The maximum deviation of 43% from the homogeneous case has been found when the activity is concentrated on the arms.     

Compact adaptive optical system based on blind optimization and a micromachined membrane deformable mirror

We describe and demonstrate an adaptive optical system based on the combination of a micromachined membrane deformable mirror and the stochastic parallel gradient descent control algorithm. This compact and relatively inexpensive adaptive optical system is used to maximize the coupling of a distorted laser beam into a single-mode optical fiber. The coupling efficiency is improved by 12 dB, and the coupling efficiency after correction is 64% of the diffraction-limited coupling efficiency.     

Zernike polynomial based Rayleigh-Ritz model of a piezoelectric unimorph deformable mirror

Piezoelectric bimorph- or unimorph-type deformable mirrors are commonly used in adaptive optics to correct for time-dependent phase aberrations. In the optics community, the surface deformations that deformable mirrors are required to achieve, are routinely and conveniently described using Zernike polynomials. A Rayleigh-Ritz structural model, which uses Zernike polynomials directly to describe the displacements, is proposed in this paper. The proposed formulation produces a numerically inexpensive model that predicts deformations with remarkable accuracy. Since design variables, such as electrode layout, material properties, and mirror dimensions, are represented analytically, the model is well suited to optimization or sensitivity analysis applications. Furthermore, since the numerical implementation is very efficient, it could be employed in closed-loop control applications. Results achieved with the proposed model compare well with results from a traditional finite element analysis as well as experimental results of a representative design.