石英砂的塑性机理研究

研究了石英砂的塑性并对其进行改善,得出石英砂颗粒大小、砖坯含水率、砖坯p H值和增塑剂含量对砖坯塑性的影响规律及机理,并且为利用石英砂而采用可塑成型去制备高性能的烧结砖探索出了合适的成型工艺条件:球磨时间24h、含水率为29%、坯料p H=9和增塑剂含量为5%。     

色谱反应分离器研究进展

本文介绍色谱反应分离器的原理及研究进展，概述在化学和生物工程产品制备方面的应用，并指出进一步研究的方向。     

A Truncated Sum of Processing‐Times–Based Learning Model for a Two‐Machine Flowshop Scheduling Problem

Scheduling with learning effects has gained increasing attention in recent years. A well‐known learning model is called “sum‐of‐processing‐times‐based learning” in which the actual processing time of a job is a nonincreasing function of the jobs already processed. However, the actual processing time of a given job drops to zero precipitously when the normal job processing times are large. Moreover, the concept of learning process is relatively unexplored in a flowshop environment. Motivated by these observations, this article addresses a two‐machine flowshop problem with a truncated learning effect. The objective is to find an optimal schedule to minimize the total completion time. First, a branch‐and‐bound algorithm incorporating with a dominance property and four lower bounds is developed to derive the optimal solution. Then three simulated annealing algorithms are also proposed for near‐optimal solution. The experimental results indicated that the branch‐and‐bound algorithm can solve instances up to 18 jobs, and the proposed simulated annealing algorithm performs well in item of CPU time and error percentage. © 2011 Wiley Periodicals, Inc.     

Dynamic deviation reduction‐based concurrent dual‐band digital predistortion

This article introduces the concurrent dual‐band digital predistortion (DPD) architecture with only one upconvertion unit, which is suitable for the linearization of wideband power amplifiers (PAs) excited by concurrent dual‐band signals. By extending the conventional dynamic deviation reduction (DDR) model to the concurrent dual‐band mode, we propose two DDR‐based concurrent dual‐band models, the dual‐band DDR (DB‐DDR) model and the simplified dual‐band DDR (SDB‐DDR) model. The performance of these two models is experimentally assessed with two types of wideband PAs (a GaN Class F PA and a GaN Doherty PA) driven by the concurrent dual‐band signal, and compared with the prior two‐dimensional digital predistortion (2D‐DPD) model and the two‐dimensional modified memory polynomial (2D‐MMP) model. The results prove the good DPD performance and low computational complexity of the proposed models. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:401–411, 2014.     

Influence of Non-Stoichiometry on the Structure and Properties of Ba(Zn1/3Nb2/3)O3 Microwave Dielectrics: II. Compositional Variations in Pure BZN

The formation of non-stoichiometric cubic perovskite solid solutions based on BaZn_1/3Nb_2/3O₃ (BZN) was examined along 10 different directions in the BaO–ZnO–Nb₂O₅ ternary system. Limited ranges of non-stoichiometry were observed along several pseudo-binaries and the BZN structure can accommodate a variety of different types of defects. Although the deviations from stoichiometry are quite small, typically ∼1 mole%, they induce large changes in the extent and stability of the 1:2 B-site ordering, the sintering and microstructure, and the dielectric loss properties. The highest Q × f s (∼110 000 at 8 GHz) in the system, which coincide with the highest degree of order, were located in two regions along the BZN–Ba₅Nb₄O₁₅ and BZN–BaNb₂O₆ lines. The results of this study provide an explanation for the large variations in crystal structure and Q × f s previously reported for BZN and other related systems (e.g., Ba(Zn_1/3Ta_2/3)O₃), and demonstrate that non-stoichiometric starting compositions provide a route to the highest Q values.     

铸造用“TD”系列粘结剂的研究

本研究以浮油沥青、木素塔尔油混合液和辅助材料“ZL”为主要原材料，以工厂残渣“DZ”为酯化剂暨改性剂，合成铸造用油类粘结剂TDI。其性能与合脂油相仿，某些性能优于合服粘结剂．由于这些原料都是工业下明料，来源丰富，合成工艺简单，成本低廉．     

采暖系统的化学清洗

叙述了采暖系统中污垢沉积的原因以及这些污垢的危害性说明通过化学清洗的方法可以有效地去除这些污垢，同时还给出了化学清洗过程中需要注意的几个要点     

A DNA-based data hiding technique with low modification rates

In 2010, Shiu et al. proposed three DNA-based reversible data hiding schemes with high embedding capacity. However, their schemes were not focused on DNA modification rate or the expansion problem. Therefore, we propose a novel reversible data hiding scheme based on histogram technique to solve the weaknesses of Shiu et al.’s schemes. The proposed scheme transforms the DNA sequence into a binary string and then combines several bits into a decimal integer. These decimal integers are used to generate a histogram. Afterwards, the proposed scheme uses a histogram technique to embed secret data. The experimental results show that the modification rate of our proposed scheme is 69 % lower than that of Shiu et al.’s schemes for the same embedding capacity. In addition, the length of the DNA sequence remains unchanged in the proposed scheme.     

Rate control of hierarchical B prediction structure for multi-view video coding

Rate control plays an important role in regulating bit streams in video coding. In order to obtain good coding performance, the hierarchical B prediction structure has been adopted in Multi-view Video Coding (MVC). However, the conventional rate control scheme is not efficient in the hierarchical B prediction structure. In this paper, we propose a rate control algorithm to address this problem. First, the accurate estimation of Mean Absolute Distortion (MAD) of the current frame is desired for both quantization parameter (QP) selection and Rate Distortion Optimization (RDO). Considering the hierarchical B structure, a bi-directional MAD prediction model is proposed to predict the MAD of the current frame by using the actual MADs of the encoded frames in the lower Temporal Layers (TLs). Second, the number of header bits has a close relationship with the TLs in the hierarchical B prediction structure. Therefore, we propose an enhanced prediction method in which a proportional relationship of the header bits is introduced if the frames are located in different TLs. Experimental results show that our proposed algorithm can achieve both accurate target bit rate and good coding performance.     

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.