Improving Reconstructed Image Quality via Hybrid Compression Techniques

Data compression is one of the core fields of study for applications of image and video processing.The raw data to be transmitted consumes large bandwidth and requires huge storage space as a result,it is desirable to represent the information in the data with considerably fewer bits by the mean of data compression techniques,the data must be reconstituted very similarly to the initial form.In this paper,a hybrid compression based on Discrete Cosine Transform(DCT),DiscreteWavelet Transform(DWT)is used to enhance the quality of the reconstructed image.These techniques are followed by entropy encoding such as Huffman coding to give additional compression.Huffman coding is optimal prefix code because of its implementation is more simple,faster,and easier than other codes.It needs less execution time and it is the shortest average length and the measurements for analysis are based upon Compression Ratio,Mean Square Error(MSE),and Peak Signal to Noise Ratio(PSNR).We applied a hybrid algorithm on(DWT–DCT 2×2,4×4,8×8,16×16,32×32)blocks.Finally,we show that by using a hybrid(DWT–DCT)compression technique,the PSNR is reconstructed for the image by using the proposed hybrid algorithm(DWT–DCT 8×8 block)is quite high than DCT.

Dynamic Compression Behavior of Ultra-high Performance Cement-based Composite with Hybrid Steel Fiber Reinforcements

Ultra-high performance cement-based composites (UHPCC) is promising in construction of concrete structures that suffer impact and explosive loads.In this study,a reference UHPCC mixture with no fiber reinforcement and four mixtures with a single type of fiber reinforcement or hybrid fiber reinforcements of straight smooth and end hook type of steel fibers were prepared.Split Hopkinson pressure bar (SHPB) was performed to investigate the dynamic compression behavior of UHPCC and X-CT test and 3D reconstruction technology were used to indicate the failure process of UHPCC under impact loading.Results show that UHPCC with 1% straight smooth fiber and 2% end hook fiber reinforcements demonstrated the best static and dynamic mechanical properties.When the hybrid steel fiber reinforcements are added in the concrete,it may need more impact energy to break the matrix and to pull out the fiber reinforcements,thus,the mixture with hybrid steel fiber reinforcements demonstrates excellent dynamic compressive performance.

Energy Absorption of Pultruded Hybrid GlassGraphite Epoxy Composites under High Strain-Rate SHPB Compression Loading

In this study, the dynamic response and energy absorption characteristics of different combinations of fiber-reinforced pultruded hybrid composites made of unidirectional glass and graphite fiber/epoxy, have been investigated. High strain-rate compression experiments were conducted on cylindrical specimens at an average strain rate of 700 /s using a modified Split Hopkinson Pressure Bar (SHPB). Failure was monitored with a high-speed video camera, and effects of hybridization on the dynamic behavior of pultruded composites were evaluated. It was found that for a given fiber volume fraction, placing glass fibers in the inner core results in a higher ultimate compressive strength, specific energy absorption, and in general a better dynamic performance with lower density.

Low-Velocity Impact and Compression after Impact(CAI)Behaviors of Carbon-Aramid/Epoxy Hybrid Braided Composite Laminates

Low-velocity impact and in-plane axial compression after impact(CAI)behaviors of carbon-aramid/epoxy hybrid braided composite laminates were investigated experimentally.The following three different types of carbon-aramid/epoxy hybrid braided composite laminates were produced and tested:(a)inter-hybrid laminates,(b)sandwich-like inter-hybrid laminates,and(c)unsymmetric-hybrid laminates.At the same time,carbon/epoxy braided composite laminates were used for comparisons.Impact properties and impact resistance were studied.Internal damages and damage mechanisms of laminates were detected by ultrasonic C-scan and B-scan methods.The results show that the ductility index(DI)values of three kinds of hybrid laminates aforementioned are 37%,4%and 120%higher than those of carbon/epoxy laminates,respectively.The peak load of inter-hybrid laminates is higher than that of sandwich-like inter-hybrid laminates and unsymmetric-hybrid laminates.The average damage area and dent depths of inter-hybrid laminates are 64%and 69%smaller than those of carbon/epoxy laminates.Those results show that carbon-aramid/epoxy hybrid braided composite laminates could significantly improve the impact properties and toughness of non-hybrid braided composite laminates.

An Efficient Test Data Compression Technique Based on Codes

This paper presents a new test data compression/decompression method for SoC testing,called hybrid run length codes. The method makes a full analysis of the factors which influence test parameters：compression ratio,test application time, and area overhead. To improve the compression ratio, the new method is based on variable-to-variable run length codes,and a novel algorithm is proposed to reorder the test vectors and fill the unspecified bits in the pre-processing step. With a novel on-chip decoder, low test application time and low area overhead are obtained by hybrid run length codes. Finally, an experimental comparison on ISCAS 89 benchmark circuits validates the proposed method

HYBRID SCHEME FOR COMPRESSIBLE TURBULENT FLOW AROUND CURVED SURFACE BODY

A hybrid central-upwind scheme is proposed. Two sub-schemes, the central difference scheme and the Roets flux difference splitting scheme, are hybridized by means of a binary sensor function. In order to examine the capability of the proposed hybrid scheme in computing compressible turbulent flow around a curved surface body, especially the flow involving shock wave, three typical eases are investigated by using detached-eddy simulation technique. Numerical results show good agreements with the experimental measurements. The present hybrid scheme can be applied to simulating the compressible flow around a curved surface body involving shock wave and turbulence.

Fractal image compression based on fuzzy theory

Though progress has been made in fractal compression techniques, the longencoding times still remain the main drawback of this technique, which results from the need ofperforming a large number of range-domain matches. The total encoding time is the sum of the timerequired to perform each match. In order to make this method more efficient in practical use, thefuzzy theory based on feature extraction of the projection and normalized codebook method has beenprovided to optimize the encoding time, based on the c-means clustering approach. The results of theimplementation of Rate Mean Square (RMS), Peak signal noise ratio (PSNR) and the encoding time ofthis proposed method have been compared to other methods like the Feature Extraction andSelf-orgarnization methods to show its efficiency.

Evaluation of the Compressive Strength of Hybrid Clay Bricks

This work has presented the evaluation of the compressive strength of hybrid clay bricks from interlocking brick making machine. The mixture of clay and cement at varying proportions was loaded into the mould compartment, mechanically rammed and hydraulically controlled. The raw clay was sourced from Ilesa and Akure in the south-western part of Nigeria. The results showed that when the cement content was 6%, the highest compressive load and energy at break were obtained in hybrid bricks from both Ilesa and Akure samples. However, the optimum service performance under compressive loading was attained at 6% cement in Ilesa hybrid bricks. Ilesa hybrid bricks possess better reliability and workability under loading than the Akure bricks.

Supercharging of Diesel Engine with Compressed Air: Experimental Investigation on Greenhouse Gases and Performance for a Hybrid Wind-Diesel System

Supercharging is the process of supplying air for combustion at a pressure greater than that achieved by natural or atmospheric induction, as applied to internal combustion engines. As a consequence of demonstrated technological, economical and energetic advantages in multiple literature evaluations concerning the large scale wind-compressed air hybrid storage system with gas turbines, the utilization of a hybrid wind-diesel system with compressed air storage (HWDCAS) has been frequently explored. These will mainly have average or small scale application such as the powering of isolated sites. It has been proven in numerous studies that the HWDCAS combined with an additional supercharging of the diesel engines will contribute to the increase of the power and efficiency of the diesel engine, the reduction of both fuel consumption and the emission of greenhouse gases (GHG). This article presents the obtained results from experimental validation of the selected design with an aim to valorize this innovative solution and become trustworthy.

Development of a Hybrid Pin Joint with a Compressed Wooden Dowel and Metal Pipe

A newly developed hybrid pin (HP), composed of a compressed wooden dowel inserted into a stainless steel pipe is suggested in this research. This configuration is expected to grant high stiffness by bending performance of the metal pipe and rich ductility through shear deformation of compressed wooden dowel without brittle split of the joint member. Experimental tests were performed in order to verify your assumptions and pursue an optimum design. Double shear test perpendicular to the grain of HP was conducted with parameter of thickness and loading direction for base member for pin’s diameter. Rotational test for mortise and tenon joint inserted with HP was performed in order to evaluate the moment resisting performance. Consequently, the hybrid pin showed satisfactory performance as shear type fastener by virtues of not only relatively high stiffness but also rich ductility originated from the properties of each component, stain less steel pipe and compressed wood.

Transverse Compressive Properties of Carbon/Glass Hybrid Thermoplastic Composite Rods

Novel carbon/glass hybrid thermoplastic composite rods having different carbon/glass ratios (24K1P,24K2P,and 24K3P) are commercially fabricated.The transverse compressive properties of these three hybrid rods were investigated.The load-displacement curve showed large nonlinear behavior and a complicated shape.In the initial stage,the load gradually increased by increasing the deformation.In the second stage,the load-displacement relation was almost linearly proportional to the displacement (stable deformation region).Subsequently,the slope decreased slightly,before the load-displacement curve showed a clear slope increase as the deformation proceeded.The fracture behavior of the hybrid rods was examined using a digital microscope.The observed fracture paths formed almost straight lines running through the loading point,the center of the cross section of carbon fiber bundles/thermoplastic epoxy,as well as the interface between the glass fiber bundles/thermoplastic epoxy and the carbon fiber bundles/thermoplastic epoxy.

Analysis of Solar Direct-Driven Organic Rankine Cycle Powered Vapor Compression Cooling System Combined with Electric Motor for Office Building Air-Conditioning

Solar energy powered organic Rankine cycle vapor compression cycle(ORC-VCC)is a good alternative to convert solar heat into a cooling effect.In this study,an ORC-VCC system driven by solar energy combined with electric motor is proposed to ensure smooth operation under the conditions that solar radiation is unstable and discontinuous,and an office building located in Guangzhou,China is selected as a case study.The results show that beam solar radiation and generation temperature have considerable effects on the system performance.There is an optimal generation temperature at which the system achieves optimum performance.Also,as a key indicator,the cooling power per square meter collector should be considered in the hybrid solar cooling system in design process.Compared to the vapor compression cooling system,the hybrid cooling system can save almost 68.23%of electricity consumption.

配筋PVA-钢混杂纤维增强水泥基复合材料梁柱边节点抗震性能试验研究

改善工程材料韧性和耐久性,提高框架梁柱节点抵抗变形和破坏的能力,是提高框架结构抗震韧性的有效途径之一。采用PVA-钢混杂纤维增强水泥基复合材料代替普通混凝土应用到梁柱边节点,考虑轴压比和加密区体积配箍率的影响,设计6个配筋PVA-钢混杂纤维增强水泥基复合材料、1个配筋单掺PVA纤维增强水泥基复合材料和1个钢筋混凝土梁柱边节点试件进行拟静力试验,分析其破坏形态、滞回曲线、骨架曲线、延性、耗能能力、钢筋应变和梁端塑性铰区转角,探讨混杂纤维的加入对梁柱边节点抗震性能的影响。结果表明:与钢筋混凝土节点和单掺PVA纤维增强水泥基复合材料节点相比,PVA-钢混杂纤维增强水泥基复合材料节点的承载力高、变形能力大、延性好、耗能能力强,抗震性能显著提升。当试验轴压比从0.12增加到0.24,梁端塑性铰区产生一定的外移,塑性性能发挥更充分,同时试件的变形能力、延性、耗能能力增加。在加密区体积配箍率减小的情况下,试件仍表现出良好的抗震性能。

玄武岩织物-钢-PVA工程水泥基复合材料单轴受压力学性能研究

本文研究了玄武岩织物和混杂短切纤维(钢纤维及PVA纤维,短切纤维总体积掺量为2%)复合作用对玄武岩织物-钢-PVA工程水泥基复合材料(BTR-HyECC)单轴受压力学性能的影响,并通过圆柱体单轴受压试验测得各试件受压性能指标,并绘制出应力-应变曲线。结果表明:当钢纤维掺量为0%(体积分数,下同)时,随着玄武岩织物的加入,试件的抗压强度、峰值应变以及抗压韧性显著提高;当钢纤维掺量增加到1%时,试件抗压强度和弹性模量达到最大;当钢纤维掺量为1.5%时,试件变形能力和抗压韧性达到最佳。基于试验数据,建立了适用于BTR-HyECC的单轴受压本构方程,拟合曲线与试验曲线吻合较好。

基于排序蒸馏的序列化推荐算法

为解决当前基于知识蒸馏的推荐算法排名有效性和效率低,以及现有知识蒸馏模型更强调的是静态和单一知识迁移的问题,提出一种基于排序蒸馏的序列化推荐算法。训练一个性能优越、规模大的教师模型,训练一个符合移动终端设备的小模型即学生模型,使学生模型在教师模型的指导下学习排序。学生模型实现了与教师模型相似的排名性能,且学生模型规模较小提高了在线推荐效率。通过在数据集MovieLens和Gowalla上的实验,验证了该模型增强了学生模型的学习效果,缓解了学生模型学习不充分导致排名不佳的问题。模型可以自然地运用于序列化推荐的模型中,具有很好的通用性。

基于风光互补发电系统的压缩空气混合储能系统容量优化

压缩空气储能系统可以有效减少因风能和太阳能随机性造成的弃风弃光现象,但其动态响应时间长,且存储规模配置不合理会影响其发展。为此首先提出液流电池与压缩空气储能组成混合储能系统解决并网型风光互补发电系统输出波动不稳定的问题;其次基于典型小时负荷、风力机发电功率和光伏发电功率,针对不同场景,以系统最大收益为目标函数,利用猫群算法优化压缩空气储能系统的容量配置;最后分析压缩空气储能系统的额定容量与额定功率对系统最大收益的影响,验证算法可靠性。结果表明,基于风力机与光伏系统的装机功率分别为20 MW和3.42 MW的场景,压缩空气储能系统容量配置为4 MW和46.5 MW∙h时,其经济性最佳,每周可节约购电成本183688.24元,周最大收益为30543.86元。

压缩空气与热化学复合储能系统反应器动态性能研究

针对压缩空气与热化学复合储能系统中,由于压缩机的波动运行而导致的反应器不稳定运行问题,通过建立热化学反应过程完备的数理模型,探究了不同工况参数对反应器内工质传热特性和甲醇裂解性能的影响规律,进而建立了反应器的运行调控策略,以实现其内部热能到化学能的高效稳定转化。研究结果表明:在反应器的变工况运行过程中,反应器内反应物和空气温度在气体流动方向分别呈现升高和降低的趋势;甲醇裂解率随空气流量和反应器空气侧入口温度的增加而增加,随甲醇流量的升高而逐渐降低,反应器空气侧入口温度的扰动对甲醇裂解率的影响程度最大,而反应器内甲醇裂解率对甲醇流量扰动的响应速度最快;通过建立前馈加反馈调控策略,分别控制进入反应器和压缩机的工质流量,在压缩机85%~110%的输入功率范围内,反应器可在1000 s内实现95%的甲醇裂解率,证明了所提出调控策略的快速响应性和有效性。

多壁碳纳米管杂化改性苯乙烯-二乙烯基苯共聚物载体的制备及性能

苯乙烯-二乙烯基苯共聚物(SDB)为载体的Pt/SDB疏水催化剂是氢-水液相催化交换(LPCE)技术的重要材料。针对SDB载体疏水性不强和强度低等问题,通过KH570,KH560和KH550硅烷偶联剂改性多壁碳纳米管(MWCNTs),再杂化改性SDB载体。结果表明:杂化改性的SDB载体的水接触角提高了20°以上,抗压强度为基础SDB载体的1.6~3.8倍,热重分析的初始热分解温度提高了4.6~15.8℃。KH570处理的MWCNTs含有双键,可实现与苯乙烯、二乙烯基苯的三元共聚且掺杂均匀,杂化改性SDB载体效果最佳。

高温后混杂纤维增强人工砂混凝土力学性能试验研究

为研究高温后纤维增强人工砂混凝土的力学性能,以历经最高温度、人工砂取代率、纤维总掺量和纤维种类为变化参数,设计并完成了40个高温后纤维增强人工砂混凝土立方体试件的轴压试验。通过试验观察了试件烧失率变化和试件的破坏过程及形态,获取了试件应力应变曲线,重点分析了历经最高温度、人工砂取代率、纤维总掺量和纤维种类对纤维增强人工砂混凝土试件抗压强度及延性的影响规律。研究结果表明,对于不同历经最高温度,试件内部结构随温度升高而破坏严重,抗压强度及延性下降明显;对于不同人工砂取代率,50%取代率的试件有着相对最优的抗压强度和延性;对于不同的纤维总掺量,1.1%纤维总掺量的试件有着相对最优的抗压强度和延性;对于不同的纤维种类,在钢纤维掺量一定时,掺入玄武岩纤维可以提升试件的抗压强度,掺入聚丙烯纤维可以提升试件的延性。

钢-PE混杂纤维水泥基复合材料动态压缩性能试验研究

将钢纤维和PE纤维混杂掺入水泥基基体材料中,控制纤维体积总掺量为2%,通过改变两种纤维比例,制成E2、E1.5S0.5、E1S1、E0.5S1.5和S2试件,应用分离式霍普金森压杆(Split Hopkinson Pressure Bar, SHPB)装置,开展了钢-PE混杂纤维水泥基复合材料在高应变率(30~120 s^(-1))条件下的动态压缩试验,从试件破坏形态、材料的动态抗压强度、韧性及其应变率效应等方面进行了分析研究。试验结果表明:①钢-PE混杂纤维水泥基复合材料表现出明显的应变率效应,其动态抗压强度、韧性以及动态抗压强度增长因子(Dynamic Increase Factor of Compressive Strength, DIF)随着应变率的增加而提高。应变率为60-80 s^(-1)时,PE纤维增韧效果更好;而应变率为100s^(-1)时,钢纤维增韧效果更优。②随着PE纤维掺量的增加,材料应力-应变曲线的应变硬化现象更明显。而钢纤维掺量达到1.5%以上且继续增大时,材料的动态抗压强度和韧性得到提高,表明一定掺量的钢纤维可以提高材料动态抗压强度的应变率敏感性。③两种纤维混杂的试件其动态压缩力学性能要优于单掺PE或钢纤维的试件,综合动态抗压强度、韧性以及DIF,得出抵抗冲击压缩荷载的最优纤维配比是0.5%的PE纤维+1.5%的钢纤维。