Efficient colour image compression using fusion approach

The aim of image compression endeavour is to reduce the total data required to represent the image, which, in turn, decreases the demand of transmission bandwidth and storage space. In this work, we propose an image fusion based idea that can be exploited extensively to reduce the file size of JPEG compressed image further. Before performing the JPEG compression, we compute both intensity and a subsampled colour representation of the image undergoing compression. Then, similar to the JPEG compression, discrete cosine transformation, quantisation and entropy coding processes are applied on these images and stored in a single image file container. In the decoder, these two images are reconstructed and fused to obtain the resultant decoded image. Our experiments show that the proposed method does meet the lower storage and bandwidth requirement by reducing the average bits per pixel of the encoded image than that of the JPEG compressed image.     

一种适用于随机检测的稳健性视频水印方法

随机检测是视频水印需要解决的关键问题之一,目前的视频水印缺乏有效的随机检测技术.对此,文中提出了一种适用于随机检测的稳健性视频水印方法.该方法先将水印信号进行BCH编码并按密钥置换,然后将编码后的数据和同步码依次嵌入到DCT块的候选中频系数中,并通过同步码来实现水印的快速随机检测.实验表明,该方法具有良好的抗噪声、视频压缩编码和裁剪性,并能实现了水印的随机检测和水印信息的字节对齐.     

Microstructure, Compression Property and Shape Memory Effect of Equiatomic TaRu High Temperature Shape Memory Alloy

The microstructure, phase transformation, compression property and strain recovery characteristics of equiatomic TaRu super high temperature shape memory alloy have been studied by optical microscope, XRD, DTA, compression tests and TEM observations. When cooling the alloy specimen from high temperature to the room temperature,β(parent phase)→β′(interphase) →β"(martensite) two-step phase transformations occur. The microstructure at room temperature show regularly arranged band morphology, with the monoclinic crystal structure. The twinning relationship between the martensite bands is determined to be (101) of Type I. Reorientation and coalescence of the martensite bands inside the variant happened during compression at room temperature. The β′→β reversible transformation contributes mainly the shape memory effect, with the maximum completely recovery strain of 2%.     

Bit rate reduction techniques for absolute moment block truncation coding

Abstract

Block Truncation Coding uses a two‐level moment preserving quantizer that adapts to local properties of the images. It has the features of low computation load and low memory requirement while its bit rate is only 2.0 bits per pixel. A more efficient algorithm, the absolute moment BTC (AMBTC) has been extensively used in the field of signal compression because of its simple computation and better MSE performance. We propose postprocessing methods to further reduce the entropy of two output data of AMBTC, including the bit map and two quantization data (a, b). A block of a 2×4 bit map is packaged into a byte‐oriented symbol. The entropy can be reduced from 0.965 bpp to 0.917 bpp on average for our test images. The two subimages of quantization data (a, b) are postprocessed by the Peano Scan. This postprocess can further reduce differential entropy about 0.4 bit for a 4×4 block. By applying arithmetic coding, the total bit reduction is about 0.3～0.4 bpp. The bit rate can reach 1.6～1.7 bpp with the same quality as traditional AMBTC.     

基于字节码例化的程序优化原理与分析

为从根本上改善Java程序运行效率,充分发挥其跨平台和分布式计算的特点,促进网络计算更快发展,本文讨论了基于部分计值的字节码例化技术,提出了将通用的应用程序代码例化为更有效的面向领域和体系结构的机制,并实现一个面向hva字节码的部分计值器Jmix。实验表明,Jmix能有效缩短字节码长度,提高应用的运行效率。     

Fiber delivered two-color picosecond source through nonlinear spectral transformation for coherent Raman scattering imaging

We demonstrate a two-color, fiber-delivered picosecond source for coherent Raman scattering (CRS) imaging through nonlinear spectral transformation. The wavelength tunable picosecond pump is generated by nonlinear spectral compression of a prechirped femtosecond pulse in a fiber wavelength division multiplexer (WDM). The 1064-nm synchronized picosecond Stokes pulse is generated through pulse carving of a continuous wave laser, nonlinear spectral broadening in 100-m standard single-mode fiber, and subsequent dispersive compression with a fiber compressor. The pump and Stokes beams are combined and delivered by the fiber WDM. CRS imaging of mouse skin is performed to demonstrate the practicality of this source.     

Analogous mechanical behaviors in [Formula: see text] and [Formula: see text] directions of Cu nanowires under tension and compression at a high strain rate

This study analyzes the plastic deformation on the atomic scale of Cu nanowires (NWs) with [Formula: see text] and [Formula: see text] orientations during uniaxial tension and compression, using a molecular dynamic simulation. The maximum local stress (MLS) method is employed to evaluate mechanical behavior during deformation. Following yielding, the flow stress strongly depends on the variation in the degree of orientation caused by twinning. Both the tension of the [Formula: see text] NW and the compression of the [Formula: see text] NW cause twin deformation and consequent geometrical softening. In contrast, the compression of the [Formula: see text] NW and the tension of the [Formula: see text] NW form twin bands and cause geometrical hardening. These behaviors result in the stress-strain curves that reveal the pseudo-skew-symmetry characteristic. With respect to the difference between the critical resolved shear stress (τ(c)) associated with the distinct orientations, τ(c) depends strongly on the surface critical resolved stress (τ(sc)). Under tension, τ(sc) depends on the degree of lattice distortion. A larger lattice distortion (pre-tensile stress) corresponds to higher τ(sc). However, under compression, a geometrical factor can be used to describe the difference in τ(sc) between the different orientations. A larger geometrical factor corresponds to a larger τ(sc).     

Molecular dynamics study on surface formation and phase transformation in nanometric cutting of β-Sn

Atomic motion and surface formation in the nanometric cutting process of β-Sn are investigated using molecular dynamics (MD). A stagnation region is observed that changes the shape of the tool edge involved in nanometric cutting, resulting in a fluctuation in the cutting forces. It is found that single-crystal tin releases the high compressive stress generated under the tool pressure through slip and phase transformation. The tin transformation proceeds from a β-Sn structure to a bct-Sn structure. The effects of the cutting speed, undeformed chip thickness (UCT) and tool edge radius on material removal are also explored. A better surface is obtained through material embrittlement caused by a higher speed. In addition, a smaller UCT and sharper tool edge help reduce subsurface damage.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00399-w     

Martensite and Reverse Transformation during Complete Cycle of Simple Shear of NiTi Shape Memory Alloy

Abstract:  Investigation into the quasi-static simple shear of shape memory alloy (SMA) was carried out. A special grip was designed which allowed replacing compression into the shear process on testing machine. At the same time the shear zone temperature was observed by an infrared camera. The mechanical and thermal characteristics of sheet specimens of NiTi subjected to superelastic shear deformation due to reversible stress-induced phase transformation were clarified. By comparison of the data, the processes of martensite and reverse transformations during the shear deformation were analysed. The investigation shows that stages of the phase transformations during the simple shear process are similar like those observed during tension test. Moreover, during the simple shear deformation no uniform temperature distributions were noticed, especially at higher shear rate, manifesting that the stress-induced phase transformation during the shear process is also inhomogeneous. The thermomechanical properties of the NiTi SMA for various shear rates were investigated. It was found that an increase in the strain rate results in an increase in temperature variation, the shear stresses and the magnitude of hysteresis loops between the forward and reverse transformations.     

缓冲材料动态压缩试验的虚拟仪器设计

基于虚拟仪器思想．用VC 开发出了材料缓冲特性测试虚拟仪器系统。系统使用搜索技术，能可靠采集显示瞬时冲击信号；使用多种数字滤波技术能有效去除信号中的噪声，采取多种曲线拟合技术以得到各种描述材料缓冲特性的曲线。并以各种方式显示之。采用曲线位图转换存储技术抓取曲线图形。以拷贝到文本文件中；能自动按要求模板生成实验报告；采用文件自动管理技术管理数据文件．提高了它的可操作性。     

Mechanical properties of alloys with reversible martensitic transformation

Characteristics of the formation of properties of alloys with reversible martensitic transformation are examined from positions of the theory of structure formation in open, highly nonequilibrium, thermodynamic systems. It is shown that strain hardening of a metal is linearly connected with change in entropy and is a measure of the nonequilibrium state of the system and that it can be used for calculating the entropy change. Based on analysis of the energy state of the material, the article establishes that it is possible to determine stress levels corresponding to instant of loss of the form memory effect with plastic deformation and to failure under a simple type of stress. Calculated values of these characteristics of alloys are in good agreement with experimental data of the authors and other published data. The thermodynamics of reversible martensitic transformation are examined.Translated from Problemy Prochnosti, No. 3, pp. 34–42, March, 1992.     

Refrigeration Carnot-type cycle based on isothermal vapour compression

A refrigeration Carnot-type cycle based on isothermal compression and two reversible expansions is proposed. Although ideal, this cycle is close to a realistic one which could be designed with existing hardware.     

University Learning and Anti-Plagiarism Back-End Services

Plagiarism refers to the use of other people’s ideas and information without acknowledging the source. In this research, anti-plagiarism software was designed especially for the university and its campuses to identify plagiarized text in students’ written assignments and laboratory reports. The proposed framework collected original documents to identify plagiarized text using natural language processing. Our research proposes a method to detect plagiarism by applying the core concept of text, which is semantic associations of words and their syntactic composition. Information on the browser was obtained through Request application programming interface by name Url.AbsoluteUri, and it is stored in a centralized Microsoft database Server. A total of 55,001 data samples were collected from 2015 to 2019. Furthermore, we assimilated data from a university website, specifically from the psau.edu.sa network, and arranged the data into students’ categories. Furthermore, we extracted words from source documents and student documents using the WordNet library. On a benchmark dataset consisting of 785 plagiarized text and 4,716 original text data, a significant accuracy of 90.2% was achieved. Therefore, the proposed framework demonstrated better performance than the other available tools. Many students mentioned that working on assignments using the framework was suitable because they were able to work on the assignments in harmony, as per their timeframe and from different network locations. The framework also recommends procedures that can be used to avoid plagiarism.     

Effects of Environmental Temperature and Compression Energy on Polymorphic Transformation During Tabletting

The effects of temperature on the polymorphic transformation and the compression of chlorpropamlde forms A and C during tabletting were investigated by X-ray diffractometry. The X-ray diffraction profiles of the sample powders deagglomerated after compression were recorded to calculate the degree of polymorphic transformation. A single punch eccentric tabletting machine equipped with two load cells (upper and lower punches) and with a noncontact displacement transducer was used to measure the compression stress, energy and distance between punches. A heater and a liquid nitrogen pool were mounted on the die of the tabletting machine, and the die temperature was controlled with a thermocontroller. Two types of compression methods, multi-tabletting at room temperature and single tabletting at 0-45°C, were used in the present study. In the first method, the stable form A or metastable form C was loaded in to the die and the sample was compressed with a compression stress of 196 MPa. Compression was repeated from 1 to 30 times. The results for forms A and C suggested that both forms were mutually transformed, and that the content of forms A and C reached equilibrium above 100 J/g of compression energy after more than 10-times compression. After 30-times compression, the content of A, C, and the noncrystalline solid form were almost constant at about 45%, 25% and 30%, respectively. The compression energy was estimated to be 500-600 J/g. In the second method, single tabletting at 0° and 45°C, the amount of form C transformed from form A at 45°C was about two times larger than that at 0°C at the same compression energy. The amount of form A transformed from form C at 45°C was almost the same as that transformed at 0°C. This suggests that the mechanochemical stability of form A was affected by compression temperature, while that of form C was independent of temperature. The crushing strength (CS) of from A tablet was about two times higher than that of form C even at the same porosity. The relationships between log (CS) of form A tablets compressed at 0 or 45°C and porosity showed straight lines with the same slope, but the slope for form C tablets compressed at 45°C was smaller than that for those compression at 0°C. From these results it appears that the transformation mechanism of forms A and C during compression was as follows: Form A or C was converted to a noncrystalline solid by mechanical energy, and then the solid was transformed into form A or C. The transformation of every form was affected by the environmental temperature.     

The interfacial behavior of water/PMMA thin film under normal compression

Molecular dynamics simulation (MD) has been used to investigate the structure property of water/PMMA interface under compression and compression release. A virtual repulsive wall was employed to generate a normal compression strain on the simulation model, leading a compressive system. In order to understand the difference of interfacial phenomenon between the system under strain and under release, the hydrogen bond and density distributions of water and PMMA along the normal direction are calculated. The results show that the hydrogen bond distribution profile of compressive system is different from that of the release system at the same strain. It demonstrates that the characteristic structure of water/PMMA interface under a compression-release cycle is not reversible.     

Effects of Environmental Temperature and Compression Energy on Polymorphic Transformation During Tabletting

Abstract

The effects of temperature on the polymorphic transformation and the compression of chlorpropamlde forms A and C during tabletting were investigated by X-ray diffractometry. The X-ray diffraction profiles of the sample powders deagglomerated after compression were recorded to calculate the degree of polymorphic transformation. A single punch eccentric tabletting machine equipped with two load cells (upper and lower punches) and with a noncontact displacement transducer was used to measure the compression stress, energy and distance between punches. A heater and a liquid nitrogen pool were mounted on the die of the tabletting machine, and the die temperature was controlled with a thermocontroller. Two types of compression methods, multi-tabletting at room temperature and single tabletting at 0–45°C, were used in the present study. In the first method, the stable form A or metastable form C was loaded in to the die and the sample was compressed with a compression stress of 196 MPa. Compression was repeated from 1 to 30 times. The results for forms A and C suggested that both forms were mutually transformed, and that the content of forms A and C reached equilibrium above 100 J/g of compression energy after more than 10-times compression. After 30-times compression, the content of A, C, and the noncrystalline solid form were almost constant at about 45%, 25% and 30%, respectively. The compression energy was estimated to be 500–600 J/g. In the second method, single tabletting at 0° and 45°C, the amount of form C transformed from form A at 45°C was about two times larger than that at 0°C at the same compression energy. The amount of form A transformed from form C at 45°C was almost the same as that transformed at 0°C. This suggests that the mechanochemical stability of form A was affected by compression temperature, while that of form C was independent of temperature. The crushing strength (CS) of from A tablet was about two times higher than that of form C even at the same porosity. The relationships between log (CS) of form A tablets compressed at 0 or 45°C and porosity showed straight lines with the same slope, but the slope for form C tablets compressed at 45°C was smaller than that for those compression at 0°C. From these results it appears that the transformation mechanism of forms A and C during compression was as follows: Form A or C was converted to a noncrystalline solid by mechanical energy, and then the solid was transformed into form A or C. The transformation of every form was affected by the environmental temperature.     

Numerical system utilising a Monte Carlo calculation method for accurate dose assessment in radiation accidents

A system utilising radiation transport codes has been developed to derive accurate dose distributions in a human body for radiological accidents. A suitable model is quite essential for a numerical analysis. Therefore, two tools were developed to setup a 'problem-dependent' input file, defining a radiation source and an exposed person to simulate the radiation transport in an accident with the Monte Carlo calculation codes-MCNP and MCNPX. Necessary resources are defined by a dialogue method with a generally used personal computer for both the tools. The tools prepare human body and source models described in the input file format of the employed Monte Carlo codes. The tools were validated for dose assessment in comparison with a past criticality accident and a hypothesized exposure.     

Polymorphic Transformation of Some Drugs Under Compression

Abstract

The existence of various crystalline forms in drugs is a phenomenon frequently encountered (about 40% of the USP XX tablet monographs with dissolution tests are concerned with such compounds). Some studies concerning trituration or grinding of polymorphs have been published; surprisingly little information is available on the transformation under compression, although of great relevance. In this work, thirty-two drugs known to exist as polymorphs were submitted to a trituration test for possible transitions. Out of the eleven transforming substances (approximately 34%), three model drugs, namely caffeine, sulfabenzamide and maprotiline hydrochloride were chosen for tabletting tests. Differential scanning calorimetry and hot stage microscopy were used to investigate polymorphic changes on the upper and lower surfaces, middle region and side of the compacts. The relationships between the extent of transformation and the compression pressure, and the energy of compression were examined, as well as the effect of drug particle size.     

Single-step fabrication of CaCO3 complex architectures

Self-organized calcite hierarchical structures are obtained by a template-and surfactant-free approach in a single step using biuret as carbonate source precursors in a solvothermal system. The calcite crystals exhibit two kinds of patterns, one of which is composed of small rhombohedron subunits with a mean scale of 5–10 μm. A possible formation mechanism is proposed. The text was submitted by the authors in English.