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891.
在成型燃料内部构建固体桥结构可有效改善其物理品质,利用不同粒径桉木屑构建了具有固体桥结构的颗粒燃料,并进一步研究了颗粒燃料的燃烧特性。提出的构建方法为同种原料不同粒径混配成型,在电子压力机上进行了粒径(0,1mm]原料混配粒径(4mm,5mm]原料的颗粒压缩成型实验,结果显示混配量5%~10%时颗粒内部长粒径粒子的交叉缠绕,可形成适量的固体桥结构,短粒径粒子填充饱满,粒子间结合紧密。较佳的混配量为5%,〖JP2〗颗粒具有较高的松弛密度,为1074.79kg/m3,最高的Meyer强度,为23.93MPa,最低的比能耗,为27.06kJ/kg,平衡含水率为11.65%,吸水速率k为0.0153min-1。在热分析仪上进行了成型颗粒燃烧实验,颗粒燃烧过程较为平稳且有所延长,在升温速率10~40℃/min的范围内,着火温度Ti在246.60~265.00℃之间,最大失重速率(dm/dτ)1max在-6.84~-29.10%/min之间,综合燃烧指数S在7.26×10-12~1.09×10-10min-2·K-3之间。在X射线荧光光谱仪上分析了颗粒灰分的元素组成,预测颗粒燃烧时具有中等或较高的结渣沾污趋势。 相似文献
892.
893.
微细铣削表面粗糙度预测与试验 总被引:6,自引:0,他引:6
分别采用正交试验回归分析法和基于正交旋转组合设计的二次响应曲面法(RSM)建立了微细铣削表面粗糙度预测模型,并在微小型车铣中心上对硬铝合金进行了试验研究,分析了铣削参数对表面粗糙度的影响.分别对两种预测模型进行了显著性检验并进行对比分析后发现:二阶响应曲面法的预测精度明显优于正交回归分析法.根据二次响应曲面法的试验结果,对回归方程中的回归系数进行了显著性检验,得出了铣削参数影响表面粗糙度的线性效应、二次效应和交互效应的显著性并进行了排序.试验结果表明:在试验采用的工艺参数范围内,对微细铣削表面粗糙度影响重要程度依次是铣削速度、每齿进给量、切削深度. 相似文献
894.
基于远程监控的农业气象自动采集系统设计 总被引:4,自引:1,他引:3
针对传统农业气象观测和当前传感器技术系统、方法存在的不足,设计了一套基于远程监控的农业气象自动采集系统,其硬件设备由农田小气候信息采集前端、视频图像信息采集前端、数据采集装置、数据传输装置和供电设备组成。该系统实现了农田小气候和视频图像信息参数采集与传输的高度集成,自动采集降水量、气温、空气湿度、风速、风向、光合有效辐射、土壤温度、土壤湿度和农作物视频图像信息,并通过远程客户端软件实现各要素信息的实时动态显示和远程监控。通过在郑州市、鹤壁市、温江市和荆州市开展的采集试验和系统试运行表明,系统显示出较好的稳定性,农田小气候和视频图像要素数据的采集、传输、动态实时显示与远程监控等各项功能均可满足各级用户需求。 相似文献
895.
将导向管喷动床改进为煤粒和稻秸粒混料气化设备,通过导向管喷动床内进行的稻秸粒与煤粒混合物料冷态流动特性试验,给出喷动的流体力学条件。研究了床层压降随表观风速的变化规律,稻秸粒和煤粒混合比例、喷口直径和导向管喷口间距3因素对床层压降与表观风速关系曲线的影响以及对物料循环速率与风量关系曲线的影响。进行了3因素12拟水平的均匀设计试验,采用SPSS软件进行回归分析,分别得到了物料循环速率、单位床高压降及单位有效功率的物料循环速率3个因变量各自与稻秸粒和煤粒混合比例、导向管喷口间距及喷口直径3个自变量之间关系的多元回归方程,用于预测稻秸煤粒混料在导向管喷动床中喷动时的流体力学参数。 相似文献
896.
897.
The influences of dissolved oxygen (DO) on the removal process of nitrogen and phosphorous in a sludge reduction system had been studied by controlling aeration amounts. It was found that under the conditions of low doses of 2,4,5trichlorophenol (TCP), endogenous sour values of activated sludge increased with the extension of low DO state duration in SBR system and the decrease of cyclic average DO, which led to a low DO environment favored the formation of simultaneous nitrification and denitrification(SND).TCP concentration was recommended as 2mg / L and cyclic average DO value in SBR system was kept at 2mg / L based on the impacts of TCP concentration on sludge reduction, removal of nitrogen and phosphorous and sludge performance. Compared with the control system, aeration amounts increased by 23% and the discharge of excess sludge decreased by 34.6%. The water quality in effluents was equivalent in the aeration sludge reduction system with 2mg/LTCP, which met the discharge standards. Therefore, it was indicated that the removal of nitrogen and phosphorous and sludge reduction can obtain excellent performance in TCP system under low DO state with removing Phosphrous rich sewage. 相似文献
898.
A new generalized conforming quadrilateral membrane element is developed by introducing additional rigid vertex rotational freedoms to the normal 4 node quadrilateral membrane element. The rotational stiffness of the present element is not zero so that the singularity of the stiffness matrix is avoided. Numerical analysis of the Cook problem cantilever beam shows that the EAE/Mem element passes the patch test and possesses good convergence, reliability, and precision without a zero energy mode. It provides a lock free solution to the MacNeal beam problem. Numerical results also show that the EAE/Mem element is insensitive to mesh distortion. The results demonstrate that the generalized conforming technique is an efficient tool for developing high performance finite element models. 相似文献
899.
LUO Xiao gang HUANG Qian PEN Cheng lin LIU Ting YIN Peng WEN Li GAO Yun hua 《保鲜与加工》2009,(1):116-120
Due to weak edges and low contrast areas in digital images, such as a left ventricle in Magnetic Resonance Imaging (MRI) images, a deformation curve may leak from the outer boundary when images are segmented using the traditional snake model. An improved algorithm based on the water balloons snake model is introduced to solve this problem. Firstly, the barycenter and the boundary shape area of the left ventricle in a digital MRI image are obtained through mathematical morphology. The left ventricular watershed line is obtained next using a watershed transform algorithm, which is taken as the initial deformation curve in a balloon snake model to capture the contour. Different snake models are tested to digitally tagged MRI images of left ventricles of small pigs. Contrast results indicate that the water balloons snake model can solve the leakage problem in traditional snake and balloon snake models. In addition, the processing speed is improved significantly. 相似文献
900.
Since P. R. China has experienced extensive land resource use, environmental degradation, lagging rural development and other difficulties in 20th century, urban countryside integration and ecological planning has become an important subject to build a harmonious society in the 21st century. The country attempted to use complexity science and ecological thinking based on recognizing the relationship between the city and countryside and raising the city countryside space ecology coupling concept to construct a city countryside space planning methods system consisting of the identification of urban and rural land uses, urban and rural non construction land planning, city countryside coupled environmental conditions assessment, coordinated city countryside space development and city countryside space system fractal optimization, and more. 相似文献