变量化约束草图驱动的药柱三维特征设计研究

为了直观而准确地支持固体火箭发动机药柱设计,提出了一种约束草图驱动的药柱三维特征造型方法。该设计方法首先通过变量化约束求解引擎对设计人员模糊的设计概念进行精确的几何坐标定位,形成一幅设计变量驱动的约束草图。然后,经过药柱特征定义,在设计规则和基于设计历史的燃面追溯统计算法的支持下,设计人员能够在约束草图上进行任意形式复杂药柱的特征定义、造型设计、燃面推移仿真与燃面统计。最后,开发了相应的药柱设计系统,并以一个管槽形药柱的设计过程,验证了本设计方法的计算效率、直观性、准确性和有效性。

基于改进量化约束集的压缩视频超分辨率重建算法

超分辨率技术是使用低分辨率图像序列来重建高分辨率图像的技术。在压缩视频的超分辨率重建中,量化约束集(QCS)作为编码模型的先验信息被广泛采用。根据窄量化约束集(NQCS)理论,利用量化误差的统计特性,提出了一种改进量化约束集(AQCS)。根据离散余弦变换(DCT)后块边界特性,提出了平滑约束集。通过对量化约束集和平滑约束集的投影进行超分辨率重建。实验结果表明,提出的基于改进量化约束集的压缩视频超分辨率重建算法较传统的量化约束集,在峰值信噪比(PSNR)和主观图像质量上有不同程度的提高,适合压缩视频的应用。

基于改进量化约束集的块效应消除算法

低比特率时,基于块离散余弦变换(BDCT)的图像压缩方法常常会引起块效应。量化约束集(QCS)作为关于编码模型的重要先验信息在块效应消除方法中被广泛地采用。利用量化误差的统计特性,提出了一种改进的量化约束集(MQCS)。实验结果表明当在现有的基于凸集投影(POCS)的去块算法中以新的约束集代替传统量化约束集,峰值信噪比(PSNR)和主观图像质量有不同程度的提高,性能与窄量化约束集(NQCS)相当。

信贷行为量化约束方法研究

用线性规划和模糊数学方法，建立了银行对企业贷款量化约束模型，研究了企业经营风险系数的确定方法。

基于非局部低秩和自适应量化约束先验的HEVC后处理算法

经高效视频编解码标准HEVC压缩后的视频在高压缩比、低码率的情况下存在明显的压缩效应。针对该问题,提出了一种基于非局部低秩(Non-local Low-rank,NLLR)和自适应量化约束(Adaptive Quantization Constraint,AQC)先验的HEVC后处理算法。该算法首先构造在最大后验概率框架下的优化问题,然后利用解码后的压缩视频和量化参数QP获取非局部低秩和自适应量化约束先验信息,最后利用split-Bregman迭代算法来解决所提的优化问题,从而有效去除压缩效应,提升重建视频质量。其中,非局部低秩先验通过构建基于相似块聚类的非局部低秩模型来获得;自适应量化约束先验通过联合不同量化参数QP下的约束特性与视频的DCT域块活动性来获得。实验结果表明,在同等码率的情况下,与HEVC标准相比,所提算法在帧内编码模式下可以达到平均0.2597 dB的PSNR提升,在帧间编码模式下可以达到平均0.2828 dB的PSNR提升。

ICU病人身体约束的影响因素分析及量化指标的构建

目的:通过调查新疆地区某三级甲等医院重症监护室(intensive care unit,ICU)约束病人情况,了解约束病人临床特点并分析其影响因素。运用风险诊断效能分析法,探讨不同影响因素对约束病人的诊断效能。以期在监护室约束病人时能够使用量化指标有目的、有效识别需要约束的病人。方法:运用约束决策轮及等级评估表对新疆某三级甲等医院ICU 280例有约束指证的病人进行评估,同时用自制的调查表进行量化评分调查;应用风险诊断效能分析法分析各变量对约束病人的诊断效能。结果:病人约束时和解除约束时镇静-躁动评分(SAS)、重症监护疼痛观察量表(CPOT)评分、谵妄评分(CAM-ICU)、非计划拔管风险评分、Morse跌倒评分、日常生活活动能力评分表评分(ADL)比较均有统计学意义(P<0.001);Logistic回归显示CAM-ICU评分、ADL评分、SAS评分、CPOT评分、非计划拔管风险评分,Morse跌倒评分是影响病人约束的独立因素(P<0.05)。筛选变量构建ICU病人身体约束量化指标用于判断病人约束与否,结果显示ROC曲线下的面积为0.993,风险诊断效能和ROC曲线分析法得出约束量表截点值为13.5分。结论:对于有约束指证病人,使用约束量化指标进行评估,若评分≥13.5分,提示病人有约束必要,需采取保护性约束。

建立银行贷款 量化约束机制的探讨

在计划经济向市场经济转换之际,专业银行向国有商业银行过渡已作为金融改革的主方向。为确保银行贷款的流动性、安全性和效益性,银行对企业发放贷款必须以企业资本金为依托,建立量化约束机制。一、问题的提出银行对企业发放贷款的管理办法,由于长期延用苏联计划经济的模式,虽经多次改革,但供给制、包下来、无量化的状况,至今仍未改变,企业依然吃银行'大锅饭'。40多年来,有两个最基本的问题没有解决:一是贷款没有'量'的界限;二是贷款没有法定偿还期和科学的计算方法。生产经营规模、资本金差异不大的企业,取得银行贷款的量却悬殊很大。企业贷款像滚雪球似地年年增量,变为企业长期占用的铺底资金。

一种基于索引约束矢量量化的脆弱音频水印算法

与传统矢量量化不同,索引约束矢量量化在量化过程中通过约束码字索引二进制形式中某一位的值来限定码字的搜索范围。利用了其特殊的码字搜索方法,提出的算法达到了在音频信号中添加水印的目的。将原始音频信号分段,每段进行DCT并提取若干中频系数构成矢量。水印嵌入时根据水印比特信息和预先设定的索引约束位的值找到匹配码字修改各段DCT中频系数。水印提取时利用传统矢量量化方法得到各量化索引值后,提取出各索引值中与嵌入端相同位的比特值即为水印信息。该方法在量化过程中嵌入水印信息,有很好的实时性。实验结果表明,利用该方法嵌入的水印为一种脆弱水印,可用于认证。

基于自适应高维度非局部总变分的压缩图像去块效应算法

经JPEG压缩后的图像存在着块效应,尤其在低码率段块效应更加明显,严重影响了图像质量和视觉效果。通过引入压缩噪声的概念,利用压缩图像及压缩比特流中获得的信息,对压缩过程进行建模。然后在最大后验框架下,联合自适应高维度非局部总变分先验及窄量化约束先验构建代价函数,提出了一种能有效去除压缩图像块效应的后处理算法。实验结果表明,相比于一些主流的去压缩效应的算法,本文算法的处理结果有更高的客观参数及更好的主观视觉效果。

基于核范数的JPEG解码算法

针对低比特JPEG图像因量化过程中产生的量化噪声问题,提出一种核范数JPEG解码算法.首先基于自然图像的低秩性得到一个带无穷范数约束问题的低秩矩阵恢复模型,其次将约束凸优化问题转换为无约束优化问题,降低其计算难度.最后,利用经典的原对偶算法结合块匹配方法处理低秩矩阵模型,得到后处理JPEG解码图像.实验结果表明,该文算法比基于总变分后处理方法在去除量化噪声方面具有优越性.

干涉SAR原始数据压缩算法的比较研究

为了更合理地选择有利于星载合成孔径雷达干涉技术的原始数据压缩算法,文章仿真了三种合成孔径雷达原始数据压缩算法,并从信号量化噪声比、相对高程误差等角度分析比较了算法的性能。仿真结果表明三种算法各有其适用范围,块自适应量化(BAQ)仍是压缩比不高时的首选,块自适应矢量量化(BAVQ)在压缩比高时性能较好,而约束式极坐标量化(RPQ)的复杂度和性能均介于二者之间。

A NOVEL ALGORITHM OF SUPER-RESOLUTION RECONSTRUCTION FOR COMPRESSED VIDEO

Super-Resolution (SR) technique means to reconstruct High-Resolution (HR) images from a sequence of Low-Resolution (LR) observations,which has been a great focus for compressed video. Based on the theory of Projection Onto Convex Set (POCS),this paper constructs Quantization Constraint Set (QCS) using the quantization information extracted from the video bit stream. By combining the statistical properties of image and the Human Visual System (HVS),a novel Adaptive Quantization Constraint Set (AQCS) is proposed. Simulation results show that AQCS-based SR al-gorithm converges at a fast rate and obtains better performance in both objective and subjective quality,which is applicable for compressed video.

Optimal distributed resource allocation in a wireless sensor network for control systems

Wireless technology is applied increasingly in networked control systems. A new form of wireless network called wireless sensor network can bring control systems some advantages, such as flexibility and feasibility of network deployment at low costs, while it also raises some new challenges. First, the communication resources shared by all the control loops are limited. Second, the wireless and multi-hop character of sensor network makes the resources scheduling more difficult. Thus, how to effectively allocate the limited communication resources for those control loops is an important problem. In this paper, this problem is formulated as an optimal sampling frequency assignment problem, where the objective function is to maximize the utility of control systems, subject to channel capacity constraints. Then an iterative distributed algorithm based on local buffer information is proposed. Finally, the simulation results show that the proposed algorithm can effectively allocate the limited communication resource in a distributed way. It can achieve the optimal quality of the control system and adapt to the network load changes.

A topology optimization method based on element independent nodal density

A methodology for topology optimization based on element independent nodal density(EIND) is developed.Nodal densities are implemented as the design variables and interpolated onto element space to determine the density of any point with Shepard interpolation function.The influence of the diameter of interpolation is discussed which shows good robustness.The new approach is demonstrated on the minimum volume problem subjected to a displacement constraint.The rational approximation for material properties(RAMP) method and a dual programming optimization algorithm are used to penalize the intermediate density point to achieve nearly 0-1 solutions.Solutions are shown to meet stability,mesh dependence or non-checkerboard patterns of topology optimization without additional constraints.Finally,the computational efficiency is greatly improved by multithread parallel computing with OpenMP.

An Improved Control Vector Iteration Approach for Nonlinear Dynamic Optimization. II. Problems with Path Constraints

This paper considers dealing with path constraints in the framework of the improved control vector iteration （CVI） approach. Two available ways for enforcing equality path constraints are presented, which can be directly incorporated into the improved CVI approach. Inequality path constraints are much more difficult to deal with, even for small scale problems, because the time intervals where the inequality path constraints are active are unknown in advance. To overcome the challenge, the ll penalty function and a novel smoothing technique are in-troduced, leading to a new effective approach. Moreover, on the basis of the relevant theorems, a numerical algo-rithm is proposed for nonlinear dynamic optimization problems with inequality path constraints. Results obtained from the classic batch reaCtor operation problem are in agreement with the literature reoorts, and the comoutational efficiency is also high.

Bipolaron in different configuration of quantum confinement

The authors used Landau-Pekar variational method to investigate a strong-coupling singlet optical bipolaron in different configuration of quantum confinement. Numerical and analytical results showed that when configuration changes from quantum dot and wire to well, confinement shows different effect on the formation of a bipolaron. In contrast to a bipolaron in a quantum dot or wire, the binding energy of a bipolaron in a quantum well increases with increasing con-finement, indicating that confinement favors bipolaron formation in a quantum well.

Vibration Spectra of Quasi-confined Optical Phonon Modes in an Asymmetric Wurtzite AlxGa1-xN/GaN/AlyGa1-yN Quantum Well

Based on the dielectric continuum model and Loudon＇s uniaxial crystal model, the properties of the quasi. confined （QC） optical phonon dispersions and the electron-QC phonons coupling functions in an asymmetric wurtzite quantum well （QW） are deduced via the method of electrostatic .potential expanding. The present theoretical scheme can naturally reduce to the results in symmetric wurtzite QW once a set of symmetric structural parameters are chosen. Numerical calculations on an asymmetric AlN/GaN/AIo,15 Gao.85N Wurtzite Q W are performed. A detailed comparison with the symmetric wurtzite QW was also performed. The results show that the structural asymmetry of wurtzite QW changes greatly the dispersion frequencies and the electrostatic potential distributions of the QC optical phonon modes.

Two-Hop Gaussian Relay Channel with Linear Relaying： Achievable Rate and Optimization Design

The relay node with linear relaying transmits the linear combination of its past received signals.The optimization of two-hop relay channel with linear relaying is discussed in this paper.The capacity for the two-hop Gaussian relay channel with linear relaying is derived,which can be formulated as an optimization problem over the relaying matrix and the covariance matrix of the signals transmitted at the source.It is proved that the solution to this optimization problem is equivalent to a "single-letter" optimization problem.We also show that the solution to this "single-letter" optimization problem has the same form as the expression of the rate achieved by Time-Sharing Amplify and Forward(TSAF).In order to solve this equivalent problem,we proposed an iterative algorithm.Simulation results show that if channel gain of one hop is relatively smaller,the achievable rate with TSAF is closer to the max-flow min-cut capacity bound,but at a lower complexity.

QoS Routing Algorithm with Multi-Dimensions for Overlay Networks

Overlay networks have emerged as a useful approach to providing a general framework for new applications and services that are to be implemented without significantly changing the IP-layer network infrastructure.Overlay routing has been used as an alternative to the default best effort Internet routing for the absence of end-to-end Quality of Service(QoS). While the former has recently been investigated, the conflict of QoS restraints and resource optimization remains unsolved. Recent studies have shown that overlay paths can give better latency, loss rate and TCP throughput. In this paper, a multi-dimensional QoS objective model based on the analysis of multiple QoS constraints has been presented, and a routing algorithm to optimise the overlay resource of its nodes and links is then proposed.In fact, the algorithm obtained multiple QoS values using probability theory to achieve the routing according to the multi-dimensional QoS objective vector of the QoS objective model. Simulation results reveals that the algorithm works better than other existing algorithms in balancing the network resources, and applications with stringent QoS requirements could be run.