Optimal entropy-constrained non-uniform scalar quantizer design for low bit-rate pixel domain DVC

In this paper, an optimal entropy-constrained non-uniform scalar quantizer is proposed for the pixel domain DVC. The uniform quantizer is efficient for the hybrid video coding since the residual signals conforming to a single-variance Laplacian distribution. However, the uniform quantizer is not optimal for pixel domain distributed video coding (DVC). This is because the uniform quantizer is not adaptive to the joint distribution of the source and the SI, especially for low level quantization. The signal distribution of pixel domain DVC conforms to the mixture model with multi-variance. The optimal non-uniform quantizer is designed according to the joint distribution, the error between the source and the SI can be decreased. As a result, the bit rate can be saved and the video quality won’t sacrifice too much. Accordingly, a better R-D trade-off can be achieved. First, the quantization level is fixed and the optimal RD trade-off is achieved by using a Lagrangian function J(Q). The rate and distortion components is designed based on P(Y|Q). The conditional probability density function of SI Y depend on quantization partitions Q, P(Y|Q), is approximated by a Guassian mixture model at encocder. Since the SI can not be accessed at encoder, an estimation of P(Y|Q) based on the distribution of the source is proposed. Next, J(Q) is optimized by an iterative Lloyd-Max algorithm with a novel quantization partition updating algorithm. To guarantee the convergence of J(Q), the monotonicity of the interval in which the endpoints of the quantizer lie must be satisfied. Then, a quantizer partition updating algorithm which considers the extreme points of the histogram of the source is proposed. Consequently, the entropy-constrained optimal non-uniform quantization partitions are derived and a better RD trade-off is achieved by applying them. Experiment results show that the proposed scheme can improve the performance by 0.5 dB averagely compared to the uniform scalar quantization.     

过氧化甲乙酮合成研究

研究了在酸性催化剂存在下，以邻苯二甲酸二丁酯作溶剂，由双氧水和甲乙酮作用制取过氧化甲乙酮溶液的工艺，并得到最佳工艺条件。结果表明，产品性能优良。     

氯氧化锆生产中除钠工艺的研究

概述烧碱生产氯氧化锆工艺的传统方法，介绍新的除钠方法，该法比传统方法具有明显的优势。     

用MH-81′状态方程模拟液氮洗涤塔

本文采用MH-81′状态方程和与密度无关的局部组成型混合法则,从二元汽-液平衡数据得到的二元相互作用参数,预测了部分液氮洗过程中的二元体系的混合焓,结果满意。采用三对角矩阵方法,对两种不同工况的液氮洗涤塔进行了模拟,计算结果与设计值和实测值符合较好。     

简析计算机网络桌面安全管理系统在企业内网中的实践

目前,众多企业构建了计算机网络管理系统,企业内网在企业发展过程中发挥了巨大的作用,但其中也存在一些安全问题。因此,我们需要应用计算机网络桌面安全管理系统,以保证数据的安全、稳定。通过分析计算机网络桌面安全管理系统在企业内网中的运作情况,提出了一些有价值的参考意见。     

硼酸镁晶须的合成研究

报道了硼酸镁晶须的合成研究结果。硼酸镁晶须是一种性能价格比高的晶须产品，利用熔盐法合成出长10—50μm、直径0．5—2μm的硼酸镁晶须。还就硼酸镁晶须增强复合材料的研究和硼酸镁晶须工业化的前景作了展望。     

Influence of fly ash and its mean particle size on certain engineering properties of cement composite mortars

An experimental investigation on the effects of incorporating large volumes of fly ash on the early engineering properties and long-term strength of masonry mortars is reported. The effect of fly ash and its mean particle size (PD) on the variation of workability and strength has been studied. It was found that fly ash and its mean particle size play a very significant role on the strength of masonry mortars. It has been observed that the early-term strength, except the mortars incorporating coarse fly ash (CFA), was slightly influenced by the replacement with fly ash. The long-term strength (both the bond strength and the compressive strength) will significantly increase, especially for the bond strength of mortars incorporating coarse fly ash. It was also found that the bond strength significantly increased as the mean particle size of fly ash decreases after 28 days curing. However, the 7-day strength was little influenced by fly ash particle size. The fluidity of composite mortar enhanced due to replace cement and lime with fly ash, and the mean PD of fly ash significantly influenced the workability.     

水煤浆添加剂及其研究进展

介绍了水煤浆添加剂结构特征对煤成浆性能影响的研究情况及新型高效添加剂的研究进展。目前制浆添加剂主要分为阴离子表面活性剂和非离子表面活性剂;我国与国外的水煤浆添加剂技术相比,还存在一定的差距,特别是分散降粘性质方面,高效、价廉、适用性广的添加剂为数并不多。     

基于ExtJS+SSH架构的民政服务信息系统设计与实现

针对传统民政办公系统结构复杂,不易维护和不易扩展的情况,提出了一种基于Ext JS+SSH(Struts2、Spring和Hibernate)架构的民政服务信息系统。按照Java EE的分层思想,通过Struts2框架实现了MVC模式,将用户界面、业务处理和数据访问三者分离,利用Spring框架统一管理系统对象以降低系统的耦合性,采用Hibernate框架实现业务数据的持久化以降低开发难度。实验结果表明,基于Ext JS和SSH架构的系统具有易维护、可扩展和运行稳定的特性。     

等离子喷涂羟基磷灰石涂层

羟基磷灰石由于具有优良的生物性能，被广泛应用于生物材料领域，而等离子喷涂制备羟基磷灰石涂层是应用最为广泛的制备方法之一。在综合国内外献的基础上，本从羟基磷灰石的本征性能、喷涂工艺的影响、结合强度和梯度涂层等方面进行综述。