铁碳微电解法处理生活污水工艺参数的优化

用自制的滚压振动磨对活性炭进行研磨,观察研磨后活性炭的形貌、比表面积和孔径;用铁碳微电解法对生活污水进行处理,研究污水pH值、铁碳质量比、反应时间、H2O2加入量对降低COD的影响.结果表明:活性炭经研磨处理后,粒径减小到1～2μm,比表面积增加了27%;在铁碳质量比为1:1、污水pH值为3.0、H2O2加入量为400...     

粉体粒径对氧化锆陶瓷断裂韧性的影响

利用放电等离子烧结技术,在温度1 400℃、压力15 MPa条件下烧结5min制备了氧化钇稳定的四方多晶氧化锆陶瓷(Y-TZP),研究了原料粉体的粒径(301.9~444.8nm)对该陶瓷晶粒尺寸和断裂韧性的影响。结果表明:随着粉体粒径的减小,Y-TZP陶瓷的晶粒尺寸逐渐增大,应力诱导相变量增加,断裂韧性增大;当粉体粒径为301.9nm时,应力诱导相变量和断裂韧度均达到最大,分别为16.18%(体积分数)和7.06 MPa·m~(1/2)。     

ZrO_2与HA复合粉体的烧结行为

将Ca3(PO4)2和Ca(OH)2粉以不同的比例混合后,加入不同量的ZrO2粉,制成料浆后球磨,然后压制,经预烧结合成HA,再在不同温度烧结来合成ZrO2/HA复合材料;用X射线衍射仪进行了物相分析。结果表明:原料粉在1 000℃预烧结10 h后,ZrO2/HA复合粉体中出现了-βCa3(PO4)2和t-ZrO2相;复合粉体在1 050~1 350℃烧结4 h后,当ZrO2加入量低(<10%)时,在相对高的温度下(>1 200℃),复合材料中只有CaZrO3相存在;当ZrO2加入量高(30%)时,在各个温度段t-ZrO2相随着CaZrO3相的减少而增加;在1 050~1 200℃范围内,HA的分解加快,t-ZrO2的稳定性增强,但在1 200~1 300℃,HA的分解停滞;不同相的出现导致没有得到理想的ZrO2/HA复合材料,并使得复合材料的密度远小于纯HA的。     

碳热/硼热还原法制备ZrB_2-SiC复合粉体

以氧化锆、氧化硅、氧化硼及活性炭为原料,采用碳热/硼热还原法制备了ZrB_2-SiC复合粉体,并对合成过程进行了热力学分析,研究了反应温度以及活性炭含量对复合粉体物相组成和显微结构的影响。结果表明:在1 400~1 450℃温度范围可以合成ZrB_2-SiC复合粉体;提高反应温度有利于合成ZrB_2-SiC复合粉体,经1 450℃保温3h反应可以得到较纯的ZrB_2-SiC复合粉体;活性炭过量50%和75%(物质的量分数)条件下制备的复合粉体的物相组成基本相同。     

不同Al2O3含量ZrO2(3Y)/Al2O3纳米复合粉体的制备与表征

采用化学共沉淀法制备了Al2O3数量分数为0%～30%的ZrO2(3Y)/Al2O3纳米复合粉体,研究了Al2O3含量和煅烧温度对粉体相结构、晶粒尺寸和晶格畸变的影响.结果表明800℃×2 h煅烧的复合粉体只出现t-ZrO2相,不出现Al2O3的任何晶相;Al2O3的添加抑制了ZrO2(3Y)晶粒的增长和四方相向单斜相的结构相变,使相变温度显著提高,晶格畸变增大.     

超临界CO_2微乳液法制备纳米氧化锆

采用超临界CO2微乳液法制备了纳米ZrO2颗粒,利用XRD、TEM、BET、TG-DSC、激光粒度分析等方法对所得的样品进行表征。结果表明:经超临界CO2微乳液过程可制得非晶相ZrO2前躯体,前躯体经550℃煅烧后转变为四方相ZrO2,900℃煅烧后转变为单斜相ZrO2,ZrO2颗粒分布均匀,粒径为40 nm左右。     

锆溶胶的制备、稳定及氧化锆粉体的特性

以氧氯化锆为前驱体,采用溶胶-凝胶法快速制备锆溶胶,凝胶后经煅烧制得氧化锆粉体,分析了锆溶胶的制备、稳定和氧化锆粉体的特性。结果表明：随着H_2O_2与ZrOCl_2·8H_2O摩尔数的比值m的增大,锆溶胶形成所需的pH值也逐渐增大;m为4～6,且pH值为3～4．5时,所得的溶胶最稳定;随m值的增大,凝胶干燥后氧化锆粉体粒径减小,分布变窄;m为4时,氧化锆粉体的平均粒径为21．4μm。粉体在450℃热处理时有四方相ZrO_2析出,随着温度升高,四方相ZrO_2结晶趋于完整,并开始析出少量单斜相;900℃时亚稳态四方相大部分转化成单斜相;1020℃时转变完成,此时得到粉体粒径在100nm左右。     

低温固相反应法合成铝酸镧粉体及表征

以九水合硝酸铝、六水合硝酸镧为原料,柠檬酸为络合剂,通过低温固相反应法制备铝酸镧前驱体,分析了该前驱体的组成及热分解过程;将铝酸镧前驱体在不同温度下煅烧制备铝酸镧粉体,研究了铝酸镧粉体的合成温度以及煅烧温度对铝酸镧粉体形貌、粒径和比表面积的影响。结果表明:铝酸镧前驱体中形成了含有La-O-Al键的络合物,当煅烧温度达到700℃时开始生成铝酸镧晶体;随着煅烧温度的升高,铝酸镧晶体的晶格畸变程度减小,晶粒逐渐长大,粉体结晶度不断提高,粒径则逐渐减小;在1 000℃煅烧得到铝酸镧粉体的粒径最小,为0.310μm,比表面积最大,为16.58m~2·g~(-1)。     

雾滴微反应器法制备纳米氧化铝粉体

以硫酸铝铵和碳酸氢铵为原料,用新技术--雾滴微反应器法制备了纳米氧化铝粉体,并与用传统沉淀法制备的纳米氧化铝粉体进行比较,用SEM和TEM等方法对制备的前驱体和最终粉体进行表征,用XRD法对最终粉体进行物相分析.结果表明:雾滴微反应器法制备的纳米氧化铝粉体比传统沉淀法制备粉体的颗粒尺寸较小,粒径分布窄,分散性好,比表面积达到138.1cm2·g-1;前驱体在1 150℃煅烧20 min可完全转化为α-Al2O3.     

Eu~(3+)掺杂Lu_2SiO_5发光粉体的制备及发光性能

分别采用尿素辅助共沉淀法和溶胶凝胶法制备Eu~(3+)掺杂Lu_2SiO_5(Lu_2SiO_5∶Eu~(3+))粉体,对比分析了煅烧温度对粉体物相组成和微观形貌的影响以及Eu~(3+)掺杂量对粉体发光性能的影响.结果表明:两种方法均可制得纯度较高的Lu_2SiO_5粉体,但溶胶凝胶法可以得到单相纯Lu_2SiO_5粉体,而尿素辅助共沉淀法所得粉体中含有少量Lu2O3杂质相;溶胶凝胶法所得粉体的粒径为200~300nm,且粉体颗粒的表面比尿素辅助共沉淀法制得的粗糙;当Eu~(3+)掺杂量(物质的量分数)为5%时,两种方法所得Lu_2SiO_5∶Eu~(3+)粉体的发光强度均达到最大,且溶胶凝胶法所得Lu_2SiO_5∶Eu~(3+)粉体的发光强度更高.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.