Very Low Bit-Rate Video Coding Based on Wavelet Transform

Two video coding schemes based on wavelet transform achieving very low bit rate are presented in this paper. The first is a hybrid motion compensated wavelet transform(MC WT)system which behaves better at very low bit rates than the block DCT residual coder. The second is a new efficient coding system based on a simple frame differencing wavelet transform(FD WT)which performs well in both PSNR and visual quality with substantially reduced complexity.

3-D Wavelet Transform for Very Low Bit-Rate Video Coding

A new improved Goh's 3 D wavelet transform(WT) coding scheme is presented in this paper. The new scheme has great advantages including a simple code structure, low computation cost and good performance in PSNR, compression ratios and visual quality of reconstructions, when compared to the other existing 3 D WT coding methods and the 2 D WT based coding methods. The new 3 D WT coding scheme is suitable for very low bit rate video coding.

A Comparative Study of High-viscosity Cement Percutaneous Vertebroplasty vs. Low-viscosity Cement Percutaneous Kyphoplasty for Treatment of Osteoporotic Vertebral Compression Fractures

The clinical effects of two different methods–high-viscosity cement percutaneous vertebroplasty（PVP） and low-viscosity cement percutaneous kyphoplasty（PKP） in the treatment of osteoporotic vertebral compression fractures（OVCFs） were investigated. From June 2010 to August 2013, 98 cases of OVCFs were included in our study. Forty-six patients underwent high-viscosity PVP and 52 patients underwent low-viscosity PKP. The occurrence of cement leakage was observed. Pain relief and functional activity were evaluated using the Visual Analog Scale（VAS） and Oswestry Disability Index（ODI）, respectively. Restoration of the vertebral body height and angle of kyphosis were assessed by comparing preoperative and postoperative measurements of the anterior heights, middle heights and the kyphotic angle of the fractured vertebra. Nine out of the 54 vertebra bodies and 11 out of the 60 vertebra bodies were observed to have cement leakage in the high-viscosity PVP and low-viscosity PKP groups, respectively. The rate of cement leakage, correction of anterior vertebral height and kyphotic angles showed no significant differences between the two groups（P〉0.05）. Low-viscosity PKP had significant advantage in terms of the restoration of middle vertebral height as compared with the high-viscosity PVP（P〈0.05）. Both groups showed significant improvements in pain relief and functional capacity status after surgery（P〈0.05）. It was concluded that high-viscosity PVP and low-viscosity PKP have similar clinical effects in terms of the rate of cement leakage, restoration of the anterior vertebral body height, changes of kyphotic angles, functional activity, and pain relief. Low-viscosity PKP is better than high-viscosity PVP in restoring the height of the middle vertebra.

An Improved SPIHT Algorithm for Image Compression in Low Bit Rate

Aiming at shortage of the SPIHT algorithm, an improved image compression algorithm is proposed, in order to overcome the shortcomings of decoding image quality and coding time, LS9/7 lifting wavelet transform is adopted. According to the characteristics of the human visual system (HVS), the scanning mode and the method to determine the threshold of algorithm are changed to improve the quality of reconstruction image. On the question of repeating scan of SPIHT algorithm, using maximum list thought, greatly reduce the computation and save operating time. The experimental results have proved that the improved algorithm of image decoding time and the quality of reconstruction images are better than the original algorithm , especially in the case of low bit rate.

COMPUTER SIMULATION FOR AN ULTRA-LOW RANGE SIDELOBE PULSE COMPRESSION SCHEME

A canceling range sidelobes scheme has been suggested by Yang Guangzheng, et al.,(1997) this technology is based on the fact that all sidelobe of group correlation function of ideal sets are zero. At first, this paper gives the best ideal sets (i. e. the best biphase code sets whose maximal sidelobe not more than 2) for all code length N≤12, which have been obtained from binary sequences by means of the best codes sieving method suggested by Yang Guangzheng, et al.(1997) Computer simulation for group correlation property of best ideal sets for code length N=12 on various conditions is made. Simulation result shows that the sidelobe level of best ideal set with no weighting is zero, under condition of zero-Doppler shift and has ultra-low sidelobe on Doppler up to 5kHz with no weighting and whose tolerance of phase and amplitude distortion is bigger too.

Low-Level Laser Therapy versus Four Layers Compression Technique in the Treatment of Venous Ulcers

Objective: The aim of the study is to evaluate the effect of low-level laser therapy in comparison to compression bandage therapy in the treatment of venous ulcers. Subjects & Methods: This study was carried out in the period from March 2013 to March 2014. The study included 40 adult patients with a diagnosis of venous ulcer classified as C6 according to the clinical classification of CEAP classification. The patients were divided into 2 groups: the first one included 20 patients treated by low-level laser therapy at the Rheumatology and Rehabilitation department, and the second group included 20 patients in whom we use four layers compression bandaging at the vascular surgery department. Results: 32 ulcers were treated in group I and 35 ulcers were treated in group II. The patients of group I were 7 (35%) females and 13 (65%) males, their age range were (24 - 56) years. The patients of group II were 11 (55%) males and 9 (45%) females;their age ranges were (32 - 50) years. Measurements of the ulcers size by (cm2) were taken at the beginning of therapy, at 1 month, at 2 months and at 3 months later on. The calculation of the area of the ulcer was done by using the graph papers to document the ulcer’s perpendicular linear dimensions. According to the size of the ulcer, some ulcers heal within 1 month (15.6%) ulcers in group I, and (28.5%) in group II. Some ulcers heal within 2 months (28%) in group I, and (37%) in group II. The remaining ulcers heal within 3 months or more which are (56%) ulcers in group I, and (34.2%) ulcers in group II. The recurrence rate of chronic venous leg ulcer in compression bandage technique used in group II was the least one as the total number of recurrent cases were 5 (25%), followed by laser therapy used in group I. Conclusion: There was no significant efficacy of the low-level laser therapy over the four layers compression technique in the management of chronic venous ulcers.

A NOVEL SLIGHTLY COMPRESSIBLE MODEL FOR LOW MACH NUMBER PERFECT GAS FLOW CALCULATION

By analyzing the characteristics of low Mach number perfect gas flows, a novel Slightly Compressible Model (SCM) for low Mach number perect gas flows is derived. In view of numerical calculations, this model is proved very efficient, for it is kept within thep-v frame but does not have to satisfy the time consuming divergence-free condition in order to get the incompressible Navier-Stokes equation solution. Writing the equations in the form of conservation laws, we have derived the characteristic systems which are necessary for numerical calculations. A cell-centered finite-volume method with flux difference upwind-biased schemes is used for the equation solutions and a new Exact Newton Relaxation (ENR) implicit method is developed. Various computed results are presented to validate the present model. Laminar flow solutions over a circular cylinder with wake developing and vortex shedding are presented. Results for inviscid flow over a sphere are compared in excellent agreement with the exact analytic incompressible solution. Three-dimensional viscous flow solutions over sphere and prolate spheroid are also calculated and compared well with experiments and other incompressible solutions. Finally, good convergent performances are shown for sphere viscous flows.

LOW MACH NUMBER LIMIT OF A COMPRESSIBLE NON-ISOTHERMAL NEMATIC LIQUID CRYSTALS MODEL

In this paper, we study the low Mach number limit of a compressible nonisothermal model for nematic liquid crystals in a bounded domain. We establish the uniform estimates with respect to the Mach number, and thus prove the convergence to the solution of the incompressible model for nematic liquid crystals.

Effect of Triisopropanolamine on the Compressive Strength and Early Hydration of Cement at Low Temperature

Triisopropanolamine (TIPA) was used as an early strength component to study its effects on mortar strength, cement paste setting time and early hydration characteristic of cement. And the early strength mechanism of TIPA at low temperature of 5 ℃ was also discussed. The results showed that, at 5 ℃, the incorporation of TIPA promoted the condensation of cement paste, shortened the initial and final setting time, and accelerated the strength development of specimens at all ages, among which the strength after 3 d increased significantly. The 1, 3, 7, and 28 d compressive strength ratios of the mortars mixed with 1% TIPA could reach 196%, 179%, 160% and 110% respectively, and the mortar strength after 3 d exceeded that of the contrast sample cured at 20 ℃. Under low temperature condition, TIPA could promote the hydration reaction of cement, shorten the induction period and advance the acceleration period. Furthermore, the maximum heat release rate and cumulative heat release quantity would be all increased, and the cumulative heat release of the cement mixed with TIPA hydrated for 12 h and 7 d increased 73% and 38% respectively. TIPA could shorten the nucleation and crystal growth (NG) stage and increase its hydration degree significantly, so it promoted cement hydration reaction. Additionally, the hydration reaction rates in phase boundary reaction (I) phase and diffusion reaction (D) phase were increased, and the duration of I process was prolonged, thereby the development of specimen strength would be accelerated. TIPA did not obviously change the types of hydration products, but increased the content of Ca(OH)2 in the samples and the degree of cement hydration. After hydration to 7 d, large amounts of hydration products, whose surface was smooth, were formed and bonded into sheets, and the structural density of samples improved significantly.

Effect of SACMA and QMW Test Methods on Compressive Properties of Composite Laminates after Low Velocity Impact

Experimental studies on the compressive behavior of composite laminates after low velocity impact was carried out with two test methods.One is SACMA Standard,and the other is a small dimensional specimen test method.Impact damage distributions,compressive failure process after impact,quasi static indentation and compression of laminates with a hole were brought into comparison between these two test methods.The results showed that there is a great difference between these two test methods.Compressive behavior of laminates after impact varies with different test methods.Residual compressive strength of laminates after low velocity impact measured with SACMA Standard can reflect stiffness properties of composite resins more wholely than that measured with the other method can do.Small dimensional specimen test method should be improved on as an experimental standard of compressive strength after impact.

Edge Oriented Compression Coding on Image Sequence

An edge oriented image sequence coding scheme is presented. On the basis of edge detecting, an image could be divided into the sensitized region and the smooth region. In this scheme, the architecture of sensitized region is approximated with linear type of segments. Then a rectangle belt is constructed for each segment. Finally, the gray value distribution in the region is fitted by normal forms polynomials. The model matching and motion analysis are also based on the architecture of sensitized region. For the smooth region we use the run length scanning and linear approximating. By means of normal forms polynomial fitting and motion prediction by matching, the images are compressed. It is shown through the simulations that the subjective quality of reconstructed picture is excellent at 0.0075 bit per pel.

Influence of prior austenite grain size on the critical strain for completion of DEFT through hot compression test

A low carbon steel was used to determine the critical strain εc for completion of deformation enhanced ferrite transformation （DEFT） through a series of hot compression tests. In addition, the influence of prior austenite grain size （PAGS） on the critical strain was systematically investigated. Experimental results showed that the critical strain is affected by PAGS. When γ→α transformation completes, the smaller the PAGS is, the smaller the critical strain is. The ferrite grains obtained through DEFT can be refined to about 3 μm when the DEFT is completed.

Effect of High Pressure Heat Treatment on Microstructure and Compressive Properties of Low Carbon Steel

The effect of high pressure heat treatment on microstructure and compressive properties of low carbon steel were investigated by optical microscope,transmission electron microscope,hardness tester and compression test methods.The results show that martensite appears in low carbon steel at 1-5GPa GPa and 950°C for 15 minutes treatment,high pressure heat treatment can improve the hardness and compressive properties of the steel,the yield strength of the steel increases with increasing pressure,and its compressive properties are better than that treated under normal pressure quenching.

THE LOW MACH NUMBER LIMIT FOR ISENTROPIC COMPRESSIBLE NAVIER-STOKES EQUATIONS WITH A REVISED MAXWELL'S LAW

We investigate the low Mach number limit for the isentropic compressible NavierStokes equations with a revised Maxwell's law(with Galilean invariance) in R^(3). By applying the uniform estimates of the error system, it is proven that the solutions of the isentropic Navier-Stokes equations with a revised Maxwell's law converge to that of the incompressible Navier-Stokes equations as the Mach number tends to zero. Moreover, the convergence rates are also obtained.

Low rank optimization for efficient deep learning:making a balance between compact architecture and fast training

Deep neural networks(DNNs)have achieved great success in many data processing applications.However,high computational complexity and storage cost make deep learning difficult to be used on resource-constrained devices,and it is not environmental-friendly with much power cost.In this paper,we focus on low-rank optimization for efficient deep learning techniques.In the space domain,DNNs are compressed by low rank approximation of the network parameters,which directly reduces the storage requirement with a smaller number of network parameters.In the time domain,the network parameters can be trained in a few subspaces,which enables efficient training for fast convergence.The model compression in the spatial domain is summarized into three categories as pre-train,pre-set,and compression-aware methods,respectively.With a series of integrable techniques discussed,such as sparse pruning,quantization,and entropy coding,we can ensemble them in an integration framework with lower computational complexity and storage.In addition to summary of recent technical advances,we have two findings for motivating future works.One is that the effective rank,derived from the Shannon entropy of the normalized singular values,outperforms other conventional sparse measures such as the?_1 norm for network compression.The other is a spatial and temporal balance for tensorized neural networks.For accelerating the training of tensorized neural networks,it is crucial to leverage redundancy for both model compression and subspace training.

Numerical Study on Low-Reynolds Compressible Flows around Mars Helicopter Rotor Blade Airfoil

High-speed rotor rotation under the low-density condition creates a special low-Reynolds compressible flow around the rotor blade airfoil where the compressibility effect on the laminar separated shear layer occurs. However, the compressibility effect and shock wave generation associated with the increase in the Mach number (M) and the trend change due to their interference have not been clarified. The purpose is to clear the compressibility effect and its impact of shock wave generation on the flow field and aerodynamics. Therefore, we perform a two-dimensional unsteady calculation by Computational fluid dynamics (CFD) analysis using the CLF5605 airfoil used in the Mars helicopter Ingenuity, which succeeded in its first flight on Mars. The calculation conditions are set to the Reynolds number (Re) at 75% rotor span in hovering (Re = 15,400), and the Mach number was varied from incompressible (M = 0.2) to transonic (M = 1.2). The compressible fluid dynamics solver FaSTAR developed by the Japan aerospace exploration agency (JAXA) is used, and calculations are performed under multiple conditions in which the Mach number and angle of attack (α) are swept. The results show that a flow field is similar to that in the Earth’s atmosphere above M = 1.0, such as bow shock at the leading edge, whereas multiple λ-type shock waves are observed over the separated shear layer above α = 3° at M = 0.80. However, no significant difference is found in the Cp distribution around the airfoil between M = 0.6 and M = 0.8. From the results, it is found that multiple λ-type shock waves have no significant effect on the airfoil surface pressure distribution, the separated shear layer effect is dominant in the surface pressure change and aerodynamic characteristics.

基于6LoWPAN的物联网寻址策略研究

在6LoWPAN(IPv6 over Low-power Wireless Personal Area Network)的基础上,该文提出应用于物联网的寻址策略,实现基于IEEE 802.15.4协议的底层异构网络与互联网的实时通信。寻址策略包括IPv6地址自动配置和报头压缩。采用的分层地址自动配置策略,首先在底层网络内部允许节点使用16位短地址导出的链路本地地址进行数据分组传输,该链路本地地址需通过执行基于分簇的重复地址检测机制保证唯一性;其次,每个底层网络中的Sink节点通过上层IP路由器获取全球路由前缀,并与接口标识符相结合,形成Sink节点的全球地址,实现底层网络与互联网的数据交换。同时,通过在报头压缩编码中植入链路本地地址和全球地址控制位,提出了一种适用于物联网应用的报头压缩方案IIPHC(IoTs IPv6 Header Compression)。如果地址类型为链路本地地址,则采用简单灵活的IIPHC1方案,如果地址类型为全球地址,则采用相对复杂但有效的IIPHC2方案。仿真及测试结果表明,基于6LoWPAN的物联网寻址策略在网络开销、时延、吞吐量、能耗等性能方面存在一定的优越性。

二维三轴编织碳纤维复合材料的冲击响应及冲击后压缩行为

采用树脂传递塑膜工艺制备碳纤维二维三轴编织复合材料,分别通过空气炮系统和落锤冲击实验系统开展了二维三轴编织复合材料在不同冲击能量下的高、低速冲击实验,并通过超声C扫描获取了不同冲击能量下的分层损伤情况,分析了二维三轴编织复合材料的高、低速冲击响应及损伤失效特性。然后,对低速冲击试样开展压缩实验,结合数字图像同步测试技术,阐明了不同冲击能量下二维三轴编织复合材料的冲击后压缩性能。结果表明,在低速冲击载荷下,随着冲击能量的增加,二维三轴编织复合材料的损伤面积等比例增大,但能量吸收增大了近2倍,在6.7 J/mm的冲击能量下,材料内部产生严重的损伤,导致其剩余强度大幅下降。二维三轴编织复合材料的弹道极限速度约为138.5 m/s,当弹体入射速度大于弹道极限速度时,其损伤面积随弹体入射速度的增大而降低。

Effect of Strain Rate on the Ferrite Grain Refinement in a Low Carbon Nb-Ti Microalloyed Steel during Low Temperature Deformation

Grain refinement is one of the effective methods to develop new generation low carbon microalloyed steels possessing excellent combination of mechanical properties. The microstructural evolution and ferrite grain refinement at the deformation temperature of 865℃, above Ar3, with different strain rates were investigated using single pass isothermal hot compression experiments for a low carbon Nb-Ti microalloyed steel. The physical processes that occurred during deformation were discussed by observing the optical microstructure and analyzing the true stress-true strain responses. At strain rates of 0.001 and 0.01s^-1, there is no evidence of work hardening behavior during hot deformation and strain-induced transformation （SIT） leads to dynamic flow softening in flow curves. Optical microscopy observation shows that ultrafine and equiaxed ferrite with grain sizes of 2μm can be obtained by applying deformation with strain rate of 0.1 s^-1 due to SIT just after deformation. Furthermore, increasing the strain rate from 0.001 to 0.1 s^-1 reduces both the grain size of the equiaxed ferrite and the amount of deformed ferrite.

Alumina/Polyimide Composite Porous Nanosolid:Dielectric Characteristics and Compressive Strength

Al2O3 porous nanosolid was prepared via solvothermal hot-press（SHP） method.The dielectric constant of Al2O3 porous nanosolid is as low as 2.34,while its compressive strength is very poor.In order to improve the compressive strength and maitain low dielectric constant,polyimide was introduced to prepare Al2O3 /polyimide composite porous nanosolid.Compared to Al2O3 porous nanosolid,Al2O3 /polyimide composite porous nanosolid possesses much higher compressive strength,which reaches its saturation value when the mass loading of polyimide is 7.75%.In addition,the in situ Fourier transformation infrared（FTIR） monitoring result reveals that Al2O3 /polyimide composite porous nanosolid is stable up to 400 °C.