玉米秸秆干燥特性的试验研究

为获取玉米秸秆干燥机设计的基础数据，对我国北方产的玉米秸秆进行工业分析、热重分析及等温干燥特性试验研究，得到了玉米秸秆水分、挥发分的相对含量、不同升温速率下的失重曲线以及各种温度下不同含水量的失重曲线。实验结果表明：玉米秸秆干燥过程中的湿球温度应控制在150℃以下，干燥时间为20～30min。     

基于气体流动计算的摩托车净化系统设计

排气管内的流场和温度场分布对排气净化系统的性能具有很大的影响,因此弄清楚摩托车排气 管内流场的分布情况十分必要。本文利用FLUENT软件对152QMI摩托车排气管内的流场进行模拟计 算。根据得到的流场分布合理布置催化转化器和二次空气喷射的位置,从而获得比较好的催化净化效 果以降低有害物的排放。     

通用变频器控制系统的探讨

本文分析了目前流行的通用变频器的两种控制方式,并对矢量控制和直接转矩控制方案作了比较和探讨,最后给出实现高性能通用变频器的途径.     

Hygrothermomechanical Effects on Laminated Composite Plates in Terms of a Higher-Order Global-Local Model

Results analytical or numerical on transverse shear stresses of laminated composite plates subjected to hygrothermomechanical effects are scarce in literature. To fill this gap, a higher-order global-local model (HGLM) satisfying the continuity conditions of transverse shear stresses at interfaces is proposed. Based on stress continuity condition between layers, the number of variables in the proposed model is independent of the number of layers of the laminate. Applying Navier's technique to equilibrium equations obtained using the principle of minimum potential energy, analytical solution of the model HGLM is derived for simply supported composite plates. Comparing the results from available three-dimensional elasticity theory and those computed from the first-order and the higher-order models, it is found that the proposed model can produce promising transverse shear stresses directly from constitutive equations without any smoothing technique. The effects of material properties, aspect ratio, side-to-thickness ratio, stacking sequence and thermal expansion coefficients on the hygrothermomechanical response have also been studied.     

气保药芯焊丝用于低温钢压力容器制造的性能研究

焊接是石油化工低温钢压力容器制造的重要工序,随着石油化工装置规模不断扩大,对低温钢压力容器的焊接质量和焊接效率提出了越来越高的要求。气保药芯焊接材料因其高质量、高效率、易于同母材匹配等优点而应用广泛,但在低温钢压力容器制造领域还应用较少。以典型的HOBART XL550气保药芯焊丝为例,根据低温钢压力容器制造的焊接要求,进行了熔敷金属扩散氢检测试验、焊丝吸潮性试验、热处理性能测试、CTOD测试。测试结果表明:XL550气保药芯焊丝最高扩散氢含量均小于4m L/100g熔敷金属,满足低氢焊接要求;焊态和热处理状态下的强度、硬度和冲击韧性也均满足压力容器的焊接要求;具有良好的止裂性能。在性能测试的基础上进行的现场对接焊试验结果表明,XL550气保药芯焊丝满足低温钢压力容器低氢焊接和热处理前后机械性能稳定的要求。     

Low-temperature Properties of Biodiesel： Rheological Behavior and Crystallization Morphology

A soybean oil derived biodiesel was prepared and blended with a conventional No. 0 petrodiesel. The pour points (PP) and the cold filter plugging points (CFPP) of biodiesel blends were evaluated on a low-temperature flow tester. Dynamic viscosities of the blends at different temperatures and different shear rates were measured on a rotary rheometer. The crystal morphologies of biodiesel blends at low temperatures were analyzed using a polarizing microscope. The results indicated that blended fuels demonstrated slight decrease in PPs and CFPPs as compared with those of neat soybean oil derived biodiesel and pure petrodiesel. Below the temperatures of PPs or CFPPs, the dynamic viscosity of biodiesel blends dramatically increased with a decreasing temperature, but decreased with an increasing shear rate, so that biodiesel blends exhibited non-Newtonian behavior. At temperatures higher than PPs or CFPPs, a linear relationship appeared between the dynamic viscosity and shear rate and biodiesel blends became Newtonian fluids. At low temperatures, wax crystals of biodiesel blends grew and agglomerated rapidly. Loss of fluidity for biodiesel blends at low temperatures could therefore be attributed on one hand to the sharp increase of viscosity and on the other hand to the rapid growth and agglomeration of wax crystals.     

Effect of reactor configuration on the yields and structures of pine-wood derived pyrolysis liquids: A comparison between ablative and wire-mesh pyrolysis

Product distributions from the pyrolysis of a common sample of pine-wood have been determined for two reactors with different configurations. The ablative pyrolysis reactor operates on the principle of “scraping” a continuous stream of biomass particles onto a heated surface under conditions of high relative motion and high applied pressure. In the wire-mesh reactor configuration, fine dispersion of a small quantity [4–6 mg] of sample and the rapid removal of volatiles from the reaction zone ensures that volatiles released during pyrolysis are captured under conditions minimising extra particle secondary reactions.

Comparison of liquid yields determined for the two reactors has been undertaken in order to assess the effect of secondary reactions on yields during ablative pyrolysis. Structural characterisations and comparison of liquids produced in the two reactors have been carried out by size exclusion chromatography, UV-fluorescence spectroscopy and FTIR spectroscopy. Slight differences in structures were apparent either due to cracking of lignin-derived macromolecules on the heated reactor surface or low molecular weight components formed during slow pyrolysis reactions of a small proportion of the feed material. Comparison of the ablative liquids with those from other ablative pyrolysis reactors show similar trends in molecular mass distributions and structures suggesting that the ablative pyrolysis process inherently cracks some liquids during volatilisation. Dry organic liquid yields from the ablative pyrolysis reactor were between 2.5 and 5.3% lower than the wire-mesh reactor between 55° and 600°C. This is believed to be a result of non-optimised reactor operation of the ablative pyrolysis reactor.     

Life assessment activities of fossil fuel power plant in the Republic of China

A service-life evaluation program on the electricity generation units of Taipower Company (TPC) has been inaugurated since 1985. Based on a survey of five different types of boiler units generated by fossil fuel, a generic procedure for the component evaluation and service-life assessment was established. The major degradation mechanisms of each of the key components/systems of the fossil fuel power units are discussed. The elements of the database software are described which are relevant in carrying out life assessment work. The limitations of applying these methods are addressed based on the experiences in performing the life assessment work for the fossil power plants of Taipower Company in the ROC.     

A Novel SAO-based Filtering Technique for Reduction in Temporal Flickering Artifacts in H.265/HEVC

This paper presents a novel filtering technique based on sample adaptive offset (SAO) in H.265/high-efficiency video coding (HEVC) for reduction in the temporal flickering artifacts and improving the coding performance. SAO is a newly introduced technique for in-loop filtering in H.265/HEVC, which derives the offsets independently for each frame in the spatial domain without considering temporal frame correlation. As a result, the temporal distortion artifacts which will have a negative effect on the subjective quality, such as flickering artifacts, cannot be effectively addressed. In this paper, the rate-distortion optimization of the newly developed SAO method, referred to as Inter-SAO, is performed on the residual samples between adjacent frames. Inter-SAO and SAO in the reference software of H.265/HEVC (i.e., the test model HM) are then combined to form the novel in-loop filter-based method, denoted as 3D-SAO filtering method, where both spatial information and temporal information are effectively utilized to reduce the overall distortion in reconstructed videos. Compared with the SAO in HM, 3D-SAO has demonstrated its advanced performance for flickering artifacts suppression. Furthermore, 3D-SAO improves the coding efficiency compared with the SAO in HM with a performance gain of up to 0.91 dB in \(\Delta PSNR\), 1.74 dB in \(\Delta PSPNR\) and 7.33 % in BD-rate reduction.