基于线性迭代的DFT调制滤波器组的设计算法

该文研究了单原型的DFT调制滤波器组的设计方法。在该方法中,滤波器组的设计问题被归结为一个无约束的优化问题,其目标函数为滤波器组的传递失真、混叠失真和原型滤波器的阻带能量的加权和。结合线性化方法,原型滤波器通过迭代求解。在单步迭代中,原型滤波器的系数通过解析式求解得到。仿真表明,与传统的设计算法相比,本文方法设计所得的DFT调制滤波器组重构误差减小了约40dB,阻带衰减提高了约2dB。并且新算法的计算复杂度明显低于传统算法。     

Mechatronic design of a self-balancing three-dimensional inertia wheel pendulum

In this paper a three-dimensional self-balancing cube is introduced. For stabilization and swing-up, reaction wheels are placed within the cube along with the actuation, electronics and sensors. This allows the cube to swing up from a rest position and to balance around the unstable steady-state positions. We conducted a design assessment to review different design approaches. For the most promising design, we formulated a parameter optimization to calculate the most suitable dimensions for the cube and the inertia elements. These results were used in the mechanical design stage to obtain the optimal design parameters for the cube in an iterative process. To show the effectiveness of the test bench we considered a proportional control law for swing-up and stabilization at the various steady state positions.     

Adaptive–interpolative binarization with stroke preservation for restoration of faint characters in degraded documents

A novel technique for binarization with stroke preservation of faint characters in degraded documents is proposed. It works in a multi-scale framework with an adaptive–interpolative thresholding technique. Instead of computing a global threshold value, it computes the local threshold values for a small set of grid points by observing the intensity pattern of the pixels lying in the concerned grid cells. Estimated thresholds are used, in turn, to compute the threshold values of all the remaining pixels using a fast-yet-efficient interpolation procedure. To handle noises in degraded images, this grid-based adaptive thresholding is applied in successively reducing scales to obtain the near-optimal binarization as a set of connected components. After a post-processing meant for stroke preservation with these connected components, we get the final output. Exhaustive experimentation and comparison with other existing methods have been successfully carried out with benchmark datasets and also with our own datasets.     

设计余弦调制QMF组的一种新方法

通过适当矩阵变换，本文首先将精确重建余弦调制正交镜像滤波器组的设计转化为一种带约束的非线性优化问题，它是一种带二次型约束的最小二乘（ＱＣＬＳ）优化问题，然后，我们提出了一种变参量的罚函数方法来有效求解该类ＱＣＬＳ优化问题，通过直接采用原型滤波器系数为优化变量，我们构造了一个特殊的凸函数作优化代价函数，故可获得该问题的全局最小点，最后，采用本文提出的设计方法进行了一个具体实例设计，结果表明我们的方法     

Optimum tilt of solar collector for maximum natural flow

A theoretical treatment to determine the natural flow rate through a flat plate collector having heat losses is made. The governing equations have been expressed in terms of Grashof and Prandtl numbers and a dimensionless heat loss parameter. The method predicts the optimum tilt of the flat plate collector for the maximum draught for a given latitude and insolation. The experimental verification of the theoretical results shows a fair agreement.

A method to calibrate the hot wire anemometer at the desired temperature is evolved for the range of velocities encountered in practice for the flat plate solar collector.     

Grey scale, the “crispening effect”, and perceptual linearization

One way of optimizing a display is to maximize the number of distinguishable grey levels, which in turn is equivalent to perceptually linearizing the display. Perceptual linearization implies that equal steps in grey value evoke equal steps in brightness sensation. The key to perceptual linearization is hence to understand the relationship between screen luminance (differences) and perceived brightness (differences). We start with an overview of psychophysical laws on the brightness-luminance relationship. We present alternative models from the literature for describing this relationship. Existing models are compared with our human-performance data that were discussed in an earlier paper. We show that Whittle’s model provides a good fit to our experimental data, provided that some of the model parameters are allowed to depend on the surround luminance. An alternative model by Kingdom and Moulden, however, needs to be modified in order to accomplish agreement with experimental data.     

微波单片集成电路的成品率优化

采用建立管芯等效电路模型、灵敏度分析以及统计勘探法对微波单片集成电路进行成品率优化，并编制了软件，加入到ＧａＡｓＩＣＣＡＤ系统中。应用该软件对Ｘ波段低噪声ＭＭＩＣ、超宽带ＭＭＩＣ放大器进行了设计，成品率有较大的提高，电路性能有所改善。     

基于序贯模块法的天然气乙烷回收工艺参数优化

随着乙烷产品价值的进一步提升,国内各大油田正大力开展天然气乙烷回收,以提高油田的综合收益。以克拉美丽气田天然气乙烷回收工艺为例,基于序贯模块法建立了天然气乙烷回收系统模型;求解得到该系统的模拟顺序后,采用HYSYS软件建立了计算模型,分析了乙烷回收工艺中各关键参数的影响,并基于?分析方法对该乙烷回收系统进行了评价;最后,以乙烷产品最小比功耗为目标函数,采用序列二次规划(SQP)优化方法对乙烷回收工艺参数进行了优化。结果表明:采用序贯模块法模拟天然气乙烷回收系统具有较好的适用性;经参数优化后,乙烷收率由92.62%提高到97.01%,乙烷产品比功耗降低了约5.4%。     

运用过程方法做好产品加工质量控制

推行GB/T19001-2000质量体系管理,运用过程方法指导产品实现过程,做好过程策划工作,对产品加工过程中从设计、工艺、人员、设备、工装、监控、环境等诸多方面进行有效的控制,达到控制产品加工质量、提高工艺工作的准确性、提高工艺管理水平的目的.     

有强内电场的GaN-基阶梯量子阱中的线性与非线性光吸收

采用密度矩阵方法,考察了带强内建电场GaN-基阶梯量子阱中的线性与非线性光吸收系数.基于能量依赖的有效质量方法,在考虑了带的非抛物性情况下,推导了结构中的精确解析的电子本征态,给出了系统中简单解析的线性与非线性光吸收系数表达式.以AlN/GaN/AlxGa1-xN/AlN阶梯量子阱为例进行了数值计算.结果发现阶梯量子阱的阱宽Lw、阶梯垒宽Lb、阶梯垒的掺杂浓度x的减小将提高体系的吸收系数.而且,随着Lw,Lb和x减小,吸收光子的能量有明显的蓝移,总吸收系数的半宽度及饱和吸收强度均减小.计算获得的部分结果与最近的实验观察完全一致.