Design of a Class of LDPC Encoder and Decoder

Low-Density Parity-Check(LDPC) codes are first introduced by Gallagerin 1960's,and independently rediscovered by both MacKay and Neal. In past few years, LDPC codes have received a lot of attention and many new developments have been brought in this area. This paper has designed a class of Low Density Parity Check(LDPC)codes based on ITU. Our design is for 6-bit quantizaton with a code rate of 0.7572 and a block size of 276 bits. This paper brings forward the architecture of the partly parallel decoder and the corresponding parallel encoder based on CPLD technology. Also we have derived the encoder scheme. And this LDPC code is used for ADSL transmission.     

地铁用间接蒸发冷却器换热性能影响因素

为解决地铁站冷却塔设置难题,提出了一种采用低速电机驱动旋转布水装置的间接蒸发冷却器,在两种布置方式下,对其换热性能进行了单因素实验,并运用正交实验法对较优布置方式下影响换热器换热的因素进行了分析。结果表明：两种布置方式下,喷嘴与蒸发冷却器的间距、两组换热管束间距均存在最佳值,喷嘴双侧旋转布水优于单侧旋转布水;换热器平行气流布置且喷嘴双侧旋转布水为较优布置方式,此时,换热器换热量随喷水量、转速、空气速度、冷却水进口温度的增加以及喷水温度、空气温度的降低而增大,其中,冷却水进口温度对换热器换热影响最为显著,其他因素对其换热的影响从主到次顺序为：喷水量、空气温度、空气速度、喷水温度、转速、冷却水流量。     

Study on the Reduction of Thermocapillary Convection of the Single-crystal Growth of Silicon under Microgravity

Float-zone method for growth of semi-conductor silicon is considering very promising under microgravity,but the effect of thermocapillary convection induced by surface tension gradient on the crystal quality is quite highlight.In the present work,a nwe method referred to as surface-cut method is suggested to reduce the melt flow.A mathmatical model to describe the thermocapillary convection in a half float-zone with surface-cut is proposed and numerical simulation for the temperature and the flow field under different surface-cut way is conducted using the finite element method.The results show that the effective reduction can be achieved and the flow will be weaked by 70% by proper increase of the surface-cut time.     

A Prediction Model Using Parallel Kernel RBF Neural Networks

Radial Basis Function Neural Networks(RBF NN) are frequently used for regression prediction.But kernel matrix computation for high dimensional data source demands heavy computing power.To shorten computing time,the paper designs a parallel algorithm to compute the kernel function matrix of RBF NN and applies it to the prediction of converter re-vanadium modeling.The paper then implements the algorithm on a cluster of computing workstations using MPI.Finally,experiment is done with the practical data to study the speedups and accuracy of the algorithm.     

Seismic Performance of Regular RC Frame with Specially Shaped Columns

According to the code and technical regulation,an irregular RC frame with specially shaped columns has been designed,which situated at the area of fortification intensity 8. Subsequently,the nonlinear dynamic analysis has been carried out for the structure by inputting ground motions in two directions. After summing up the calculation results,this paper has examined seismic performance of the structure under the rare seismic actions and given a primary evaluation on the structure to see if it could achieve the predetermined anti-seismic aims. It indicates that the structure designed according to the codes can achieve the predetermined anti-seismic aim under the rare earthquake.     

Inelastic Seismic Response of Ordinary Reinforced Concrete Regular Frames

With an inelastic dynamic analysis program developed by the authors, seismic response analysis of regular RC frames designed to Chinese codes in different earthquake fortification zones are carried out. The results indicate that the displacement responses of structures are improved due to the more rigorous limitation on the inter-story drift under frequent earthquakes in the revised codes. The frames in seismic-intensity-9 zone designed to the former codes and the revised codes form plastic energy-dissipated mechanisms mostly With beam hinges, which can satisfy the requirement of seismic performance expectably. The frame in seismic-intensity-8 zone designed to the former code forms a plastic energy- dissipated mechanisms mostly with column hinges and shows a risk of occurrence of story-sway mechanism, while the frame in seismic-intensity-8 zone designed to the revised codes exhibits a relatively improved seismic performance but still with excessive column hinges, which suggests a need to further increase the column moment amplification measures for this kind of frames. The frame in seismic-intensity-7 zone shows a somewhat improved seismic performance than the frames in seismic-intensity-8 zone, but the protection to columns by the seismic measures is sill insufficient, which indicates that the column moment amplification measures for this kind of frames should be enhanced further.     

Effects of transverse rotating magnetic field on thermocapillary flow under microgravity

Semiconductor melt is electrically conducting, which makes it possible to apply magnetic fields to control the thermocapillary convection induced by surface tension in the floating zone under microgravity, and ultimately to control grown crystal quality. In the present paper, based on the comparison between the transverse static magnetic field and the rotating magnetic field(RMF), we focuses on the effects of RMF on thermocapillary convection. Results indicate that in the RMF, the induced Lorentz force is effective in stirring the melt in the azimuthal direction and suppressing axial convection, and both effects are beneficial for the three-dimensional melt convection returning to a steady axisymmetric flow. The RMF is a promising method for convection control in floating zone for semiconductor crystal growth.     

Influences of Microgravity and Simulated Microgravity on Plant Growth and Development

How plants survive and adapt to microgravity environments is highlight problem in space biology. Research progress on influences of microgravity and simulated micrograviy on plant growth and development is reviewed. The advance in studies on physiological and biochemical characteristic changes in microgravity or simulated microgravity environments is specially discussed. Experment evidence shows that calcium concentration and distribution changed under microgravity stimulate and then Ca2+ as a second message in transmission related enzyme activity. It is pointed out that further researches should focus on difference express of involved genes and mechanism and applications in such fields as germination of aging seed , accumulation of secondary metabolite and protoplasm fusion under microgravity environments.     

Experiments on Convective Heat Transfer for Various Media Flowing Turbulently in Tubes with Three Dimensional Internally Extended Surface

This paper presents the experimental results of convective heat transfer performance in 5 copper tubes with three dimensional internally extended surface, with flow of various test fluid in the Reynolds number range of 8,000 to 80,000. Water and mixture of ethylene glycol with water (the ethylene glycol weight content equals 55%) are chosen as test fluid. The effect of the physical properties for test fluid on heat transfer performance in the tubes with three dimensional internally extended surface is discussed. The heat transfer correlation is obtained by the experimental data.     

A Method to Improve the Decoding Iteration Convergence Performance of Turbo Codes

Turbo codes is an effective method for digital communication systems to get near channel capacity error correcting performance, its iteration convergence performance is the key factor for practicability. Based on the universal decoding method of Turbo codes, a step increment factor was introduced in the paper to improve the iteration convergence performance. The method to generate the step increment factor was also presented as well as its' computer simulations. Simulation results show the method proposed can improve the convergence performance efficiency for Turbo codes with short interleaver.     

Seismic Assessment of RC Frame Structure Based on New Design Codes

The national structural codes GB50010-2002 and GB 50011-2001 have been modified in many aspects compared with the old ones. To verify the effectiveness of structural capacity design provisions in the new codes, firstly, two typical RC frame structures of Grade 2 in intensity-category 8 and Grade 1 in intensity-category 9 are designed according to the new codes. Then, nonlinear dynamic analyses of the two structures are carried out under excitations of several ground motions with the fortification and rare intensity levels. With the analysis results the availability of strong column weak beam is checked carefully, which is desirable with capacity design measures of RC frame in Chinese new structural design code. The conclusions drawn from the analysis are helpful to structural design and local modification of the codes.     

Conversion of flow pattern in the slender crucible by detached solidification

When the top surface is non-slip solid and the ratio between height and radius of crucible equals 2, the finite-difference method is adopted to carry on three-dimensional numerical simulation on the thermocapillary convection in detached solidification under microgravity. The distributions of velocity and temperature in the melt are obtained as the width of gap in crucible is selected as 0.1, 0.075 and 0.05, respectively. The results show that when the Marangoni number is small, there is one steady toroidal roll cell near the lower free surface, and the flow of melt is steady and weak. With the increase of Marangoni number, the flow is expanded toward the inner part of melt gradually and the velocity of flow on the lower free surface increases. When the Marangoni number exceeds the critical value, the flow of melt becomes unstable.     

雷蒙德氏棉DnaJ蛋白的生物信息学预测及盐胁迫下的表达分析

Dna J蛋白是一类很大的蛋白家族,是近年来研究较多的与胁迫反应等相关的蛋白。本文利用生物信息学手段,系统研究了雷蒙德氏棉(Gossypium raimondii)Dna J蛋白的数目、分类、染色体定位、亚细胞定位、进化以及在旱地棉(Gossypium aridum)和克劳茨基棉(G.klotzschianum)盐胁迫下的表达模式。结果显示:雷蒙德氏棉基因组有119个Dna J蛋白,长度从73个氨基酸到2574个氨基酸不等;在13条染色体上不均匀分布,且具有不同的亚细胞定位;Dna J结构域大致被分为9个小组,每个小组都有与拟南芥同源的基因;盐胁迫下,鉴定到旱地棉和克劳茨基棉共同差异表达的Dna J基因3个,在旱地棉盐胁迫整个过程中差异表达的基因2个。雷蒙德氏棉Dna J基因家族的鉴定和分析,将为进一步研究Dna J基因家族的功能奠定一定的基础。     

Parallel Operating the 13-Bit Lattice Gas Automata Model

The parallel operation mechanism of 13 Bit lattice gas automata model, which can quickly compute and include more sites, is presented. Via coding and computing for particles of sites by bit, the parallel computing is achieved by transfering the particles propagation and collision into its backup and reloading. This mechanism can simulate correctly and validly some fluid motion with complex geometry boundary, such as flow through coke porous media. [WT5HZ]     

Two Dimensional Bar Code in medicine Trade Logistic Management System

The characteristics of two dimensional bar code are analyzed, then the technological characteristics and the composition of logistic bar code are discussed.Through the analysis of application in medicine trade logistics management system,the PDF417 two dimensional bar code is used to make out a selling invoice, medicines stock,etc. With PDF417 two dimensional bar code , the medicine trade logistics management system overcomes many difficult problems, makes the whole system to be more efficient, completes the plan, organization, coordination and control of trade partners, logistic, information ,business,finance etc., and strengthens the connection between the trade partners.     

Rut resistance Properties of a Large stone Flexible Base under Heavy Loads

The rut resistance properties of large stone flexible bases are studied, taking into consideration heavy loads and using computer simulation and numerous indoor tests. In computer simulations of large stone flexible bases, a calculation method was formulated for predicting asphalt pavement rut under dynamic loads. The method was based on the coupling of vehicle dynamic loads and pavement surface unevenness. The results of indoor testing and three dimensional numeric calculation under dynamic loads are confirmed by tracking observation results of a test road. We conclude that the rut resistance properties of large stone flexible base asphalt pavement built using low grade asphalt and low crush value high performance aggregate with reasonable gradation is no worse than that of the semirigid base asphalt pavement, and that ruts mainly are caused by the lateral shear.     

Improved CMI code in passive induction setting system 〖JP〗

Aiming at the low energy transmission efficiency of the passive induction setting system with the existing codes, an improved CMI code is proposed as baseband code by changing the equivalent average time of high level during a code cycle under 2ASK modulation. The properties are analyzed, such as energy transmission efficiency, power spectrum and the error probability in incoherent demodulation in AWGN channel. The code is successfully applied to passive induction setting system, and the decoding method and measured voltage waveform are given. With the code, the energy transfer efficiency is improved by 60% than that of CMI code. It is not only beneficial to energy transmission, but also has the merit of CMI code that the bit timing information is extracted easily, which is fully utilized in incoherent demodulation to solve the sampling moment error accumulation problem resulted from the instability of internal oscillator.     

Multiple Turbo Codes for Satellite Communications

Satellite communication channel has the characteristic of power limited, band abundance, and powerful error correcting ability FEC scheme is needed. For its near Shannon limit error correcting capability, Turbo codes may be suitable for satellite communication systems. The multiple Turbo codes can utilize channel capacity sufficiency and overcome the disadvantages of power limited for satellite communication systems. Force on the needed for satellite communication systems, multiple Turbo codes is adopted and server decoding schemes were proposed with simulation. Simulation results show that, the schemes proposed can get near channel capacity error correcting performance with short code block.     

Direct generation of rough cut numerical control code from industrial CT slice images

This paper proposes a new method of generating a rough cut Numerical Control(NC) codes directly from industrial computerized tomography(CT) slice images for the products which work-piece did not need to be redesigned.The contour structure data of the work-piece are obtained by the threshold segmentation,edge extraction and contour tracing. The inner and outer contours are judged,and the tool radius compensation and the allowance reservation are performed by offsetting the contours according to the judgments. The authors generate the rough cut NC code cut area distinguishing and rough cut path generating in a slice by slice manner. In contour offsetting step, a new approach is proposed to judge inner and outer contours. A software system is developed to generate NC codes. An example is used to verify this approach and results show the feasibility and validity of the approach.     

Stochastic Response Surface Method Based on Radial Basis Functions

For non-ideal interpolation results of complex implicit nonlinear functions between non-normal distribution response and standard normal distribution inputs using stochastic response surface method, radial basis functions was used to replace Hermite polynomials so as to solve complex implicit nonlinear function interpolation problem for its excellent performance on scattered data interpolation. A few nonlinear analytical functions and uncertainty problems of the load carrying capacity of single circular concrete filled steel tubule (CFST) arch were used as examples to test and verify the precision of proposed method in non-normal distribution response interpolation and its engineering applicability. The results show that stochastic response surface method based on radial basis functions performs well in fitting highly nonlinear input implicit functions, and can achieve high precision on multi-parameters CFST arch load carrying capacity uncertainty problems. Meanwhile, the method has less sample points compared to the Hermite polynomials method.