酉变换准正交空时编码

设计了一种采用预编码方式的准正交空时编码(quasi-orthogonal space time code, QOSTC),其编码方案是首先对发送信号向量进行与信道状态信息无关的酉变换,然后再进行正交编码.酉变换可将QOSTC信道能转化为并行复用传输信道,实现无符号间干扰的高速率并行传输,且接双端信号的最大似然(maximum likelihood,ML)符号译码可简化成线性译码,从而可采用简单的线性检测降低译码复杂度.仿真结果表明,在高信噪比下,酉变换的QOSTC线性检测比没有酉变换的QOSTC的ML检测差2dB左右,但其分集度几乎相同.     

Properties of the linear canonical integral transformation

We provide a general expression and different classification schemes for the general two-dimensional canonical integral transformations that describe the propagation of coherent light through lossless first-order optical systems. Main theorems for these transformations, such as shift, scaling, derivation, etc., together with the canonical integral transforms of selected functions, are derived.     

仿射变换下的分类识别

特征提取和分类识别是统计模式识别中两大关键步骤。显然,不同的特征提取方法与不同的分类器相结合,识别性能往往是不同的。从微分几何的角度出发,可将特征系数的获得看成线性几何变换,即仿射变换,据此在黎曼空间提出一种基于黎曼度量的分类识别方法。通过对经典最近邻分类器的线性加权,达到更有效地分类识别。不但在理论上将特征系数提取与分类识别合理的结合起来,而且由人脸识别实验表明该方法的有效性,该方法比传统方法的识别率有约 3%的提高。     

线性正则域的Hartley变换及其不确定性原理

Hartley变换是傅里叶变换的推广, 它的一个非常好的性质就是把实信号变换成实信号, 从而减少计算量。近些年, 随着分数阶傅里叶变换在信号处理中被广泛的应用, 线性正则变换也逐渐被应用到信号处理, 所以把Hartley变换推广到正则域是一个有研究价值的问题。本文首先通过变化傅里叶变换域Hartley变换的核函数, 得到了一个具有共轭性的核函数, 之后, 通过把该核函数替换成线性正则变换的核函数, 从而得到了正则域的Hartley变换, 在这个定义的基础上, 得到了正则域Hartley变换满足实数性质和奇偶不变性, 之后再利用线性正则变换的Heisenberg不确定性原理, 得到了正则域Hartley变换的Heisenberg不确定性原理。     

Analysis of random transformation errors for linear electronic systems

Transformation errors for linear electronic systems are analyzed that lead to presence in systems of natural low-frequency noise showing properties of local uniform random processes. __________ Translated from Metrologiya, No. 10. pp. 10–14, October, 2007.     

Milling parameter optimization through a discrete variable transformation

Although milling is one of the most common chip metal removal processes, little has been done to aid in identifying the optimum operational conditions for milling processes. In this paper, a mathematical model for milling operations is developed and the five primary control variables identified. The model is then decomposed and an efficient optimization procedure developed for control variable identification.     

Optimising end-of-life system dismantling strategy

The management of end-of-life systems is becoming a major concern for systems manufacturers, as the negative impact of these systems on the environment is a matter of increasing public awareness, and their appropriate treatment offers economic opportunities. In this context, the disassembly of these systems in order to recycle their components is a possible and sound option that can make it possible to sustain economical progress while respecting environment requirements. The work undertaken in this paper considers modelling and optimising issues of such disassembly activities. An integrated approach is proposed to model and optimise the selection of valuable components of end-of-life systems, their recycling options and the way to obtain them. Because the framework of such problems is highly uncertain, we propose the use of Bayesian networks and their extension in terms of influence diagrams as mathematical tools for structuring and managing uncertainties. With this approach, one can take into account uncertainties rising from different sources on one hand and as a support for optimisation on the other hand.     

Classification of lossless first-order optical systems and the linear canonical transformation

Based on the eigenvalues of the ray transformation matrix, a classification of ABCD systems is proposed and some nuclei (i.e., elementary members) in each class are described. In the one-dimensional case, possible nuclei are the magnifier, the lens, and the fractional Fourier transformer. In the two-dimensional case we have-in addition to the obvious concatenations of one-dimensional nuclei-the four combinations of a magnifier or a lens with a rotator or a shearing operator, where the rotator and the shearer are obviously inherently two-dimensional. Any ABCD system belongs to one of the classes described in this paper and is similar (in the sense of matrix similarity of the ray transformation matrices) to the corresponding nucleus. Knowledge of a nucleus may be helpful in finding eigenfunctions of the corresponding class of first-order optical systems: one only has to find eigenfunctions of the nucleus and to determine how these functions propagate through a first-order optical system.     

A generalized non‐linear transformation for evaluating singular integrals

In this paper, we propose a function which, according to a parameter included therein, generates a new sigmoidal transformation and converges to the well‐known Sato polynomial transformation. Following well‐established procedures in the literature, we employ the present transformation in the numerical evaluation of weakly singular integrals, Cauchy principal value integrals and Hadamard finite‐part integrals. By several numerical examples it is shown that the present transformation is available for all kinds of singular integrals mentioned above and, in some cases, gives better results compared with those of traditional non‐linear transformations. Copyright © 2005 John Wiley & Sons, Ltd.     

实施技术改造 确保气体装置平稳运行

为减少空压机的非计划停机次数 ,采取了改造测量及联锁方式、增设断电延迟停机和改进监测等手段 ;为实现供氮和供风系统的联网运行 ,采用了增设气体跨线的方案。实施这些改进方法后 ,达到了确保气体装置稳定运行的目的。     

硅微陀螺信号处理方法——基于前向线性预测小波变换方法

为补偿漂移误差对硅微陀螺的测量精度造成的损失,针对漂移误差易受外部环境噪声影响的特点,提出了一种基于前向线性预测（FLP）的小波变换（WT）处理方法——DWT-FLP算法,并通过硅微陀螺试验对其进行了验证。该方法利用快速小波变换算法进行信号的小波分解和小波重构,并将FLP方法用于小波分解系数的重构,比较显著地提高了重构信号的精度。对于4尺度的db4小波变换,40阶FLP的滤波方法可以将硅微陀螺静态漂移的标准差提高4.8倍,动态测量过程信噪比可以提高6.5dB,并且该算法的实时性也可以满足实际工程的需要。     

Analysis of left-truncated right-censored or doubly censored data with linear transformation models

We analyze left-truncated right-censored (LTRC) data or doubly censored data using semiparametric transformation models. It is demonstrated that the extended estimating equations of both?Cheng et al. (Biometrika 82:835?C845,?1995) and?Chen et al. (Biometrika 89:659?C668,?2002) can be used to analyze LTRC data or doubly censored data when left-censored variables are always observed. The asymptotic properties of the proposed estimators are derived. A simulation study is conducted to investigate the performance of the proposed estimators.     

Reconstruction of chaotic oscillations after passage through linear filters

An analysis is made of the diagnostics of chaotic oscillations generated by a dynamic system and distorted by some linear inertial circuit. A method is developed to reconstruct the initial signal and determine the characteristics of the distorting filter using a time series of the process under study. Pis’ma Zh. Tekh. Fiz. 25, 55–60 (February 26, 1999)     

Optimising industrial hemp fibre for composites

The optimisation of New Zealand grown hemp fibre for inclusion in composites has been investigated. The optimum growing period was found to be 114 days, producing fibres with an average tensile strength of 857 MPa and a Young’s modulus of 58 GPa. An alkali treatment with 10 wt% NaOH solution at a maximum processing temperature of 160 °C with a hold time of 45 min was found to produce strong fibres with a low lignin content and good fibre separation. Although a good fit with the Weibull distribution function was obtained for single fibre strength, this did not allow for accurate scaling to strengths at different lengths. Alkali treated fibres, polypropylene and a maleated polypropylene (MAPP) coupling agent were compounded in a twin-screw extruder, and injection moulded into composite tensile test specimens. The strongest composite consisted of polypropylene with 40 wt% fibre and 3 wt% MAPP, and had a tensile strength of 47.2 MPa, and a Young’s modulus of 4.88 GPa.     

Optimising product configurations with a data-mining approach

Customers benefit from the ability to select their desired options to configure final products. Manufacturing companies, however, struggle with the dilemma of product diversity and manufacturing complexity. It is important, therefore, for them to capture correlations among the options provided to the customers. In this paper, a data mining approach is applied to manage product diversity and complexity. Rules are extracted from historical sales data and used to form sub-assemblies as well as product configurations. Methods for discovering frequently ordered product sub-assemblies and product configurations from ‘if-then’ rules are discussed separately. The development of the sub-assemblies and configurations allows for effective management of enterprise resources, contributes to the innovative design of new products, and streamlines manufacturing and supply chain processes. The ideas introduced in this paper are illustrated with examples and an industrial case study.     

Optimising the bioactivity of alkaline-treated titanium alloy

A layer of sodium titanate hydrogel on titanium alloy (Ti6Al4V) induces apatite formation in simulated body fluid (SBF). This paper seeks to determine the parameters of alkaline-treated and subsequent heat treatment which lead to the most rapid formation of apatite. Specimens were soaked in 3, 5, 10 or 15 M solutions of NaOH at temperatures of 60 or 80 °C for 1, 3 or 7 days. It was found that the optimum treatment for the Ti6Al4V alloy was a 3-day soak in 5 M NaOH solution at 80 °C. Specimens treated under these optimum conditions were subsequently heat-treated at 500, 600, and 700 °C for 1 h so as to consolidate the sodium titanate hydrogel layer and improve its bonding to the substrate. Treatment at 600 °C resulted in the best bonding and the optimum rate of apatite formation. On soaking in simulated body fluid (SBF), apatite formed within 3 days, as compared to the 7-day formation, which was the best rate previously reported. The acceleration in the rate of apatite formation is significant, as it should allow for earlier load bearing of prostheses following implantation.     

Optimising the energy consumption on pultrusion process

This study is based on a previous experimental work in which embedded cylindrical heaters were applied to a pultrusion machine die, and resultant energetic performance compared with that achieved with the former heating system based on planar resistances. The previous work allowed to conclude that the use of embedded resistances enhances significantly the energetic performance of pultrusion process, leading to 57% decrease of energy consumption. However, the aforementioned study was developed with basis on an existing pultrusion die, which only allowed a single relative position for the heaters.In the present work, new relative positions for the heaters were investigated in order to optimise heat distribution process and energy consumption. Finite Elements Analysis was applied as an efficient tool to identify the best relative position of the heaters into the die, taking into account the usual parameters involved in the process and the control system already tested in the previous study. The analysis was firstly developed based on eight cylindrical heaters located in four different location plans. In a second phase, in order to refine the results, a new approach was adopted using sixteen heaters with the same total power. Final results allow to conclude that the correct positioning of the heaters can contribute to about 10% of energy consumption reduction, decreasing the production costs and leading to a better eco-efficiency of pultrusion process.     

Optimising space utilisation in block stacking warehouses

Block stacking storage is an inexpensive storage system widely used in manufacturing systems where pallets of stock keeping units (SKUs) are stored in a warehouse at the finite production rates. However, determining the optimal lane depth that maximises space utilisation under a finite production rate constraint has not been adequately addressed in the literature and is an open problem. In this research, we propose mathematical models to obtain the optimal lane depth for single and multiple SKUs where the pallet production rates are finite. A simulation model is used to evaluate performance of the proposed models under stochastic uncertainty in the major production parameters and the demand.     

Optimising the palletisation of cylinders in cases

Summary This paper is concerned with the analysis of the packing arrangements of cylindrical objects into a rectangular case with respect to the palletisation efficiency of the resultant case. A set of regular arrangements are considered. The size and shape of the surrounding case depends not only on the number of rows and the number of cylinders per row but also on the angle between the centres of cylinders in adjacent rows. Previous theoretical results on the palletisation of rectangular boxes are used to develop an algorithm for determining the optimal angle for any arrangement. Arrangements with angles of 0° or 30° are often used in practice as they are easy to load. The expected optimality of this practice is investigated by an empirical study.