油溶性纳米TiO2粒子的制备及其结构表征

利用液相沉积法制备十二烷基三甲氧基硅烷(DTMS)修饰的油溶性纳米TiO2粒子,研究修饰温度、修饰时间和修饰剂用量对TiO2油溶性以及在基础油中分散稳定性的影响,采用红外光谱仪(FT-IR)、透射电子显微镜(TEM)进行了结构表征.结果表明:修饰温度为40℃、修饰时间为12 h、修饰剂与TiO2比例为2∶1(摩尔比)时,所得粒子具有最佳亲油化度和分散稳定性;纳米TiO2粒子表面的DTMS修饰膜,可有效控制粒径的过度增长,避免粒子间的团聚,增强了纳米TiO2在基础油中的分散稳定性.     

用正交实验法优化纳米铋粉制备工艺参数

采用高能球磨的方法，直接分散铋粒制备纳米铋粉。实验选用无水乙醇为液相介质、聚乙烯吡咯烷酮（PVP）和硬脂酸作为复合修饰剂，通过正交实验研究铋粒的加入量、复合修饰剂的相对用量、转速和时间等工艺参数对纳米铋粉的产量、产率和粉体的特征数据D50的影响。研究表明：本方法能够制备出纯净的纳米铋粉；适当增加铋粒的加入量，减少修饰剂的相对用量，降低转速，适当缩短时间，有利于降低颗粒的平均粒径，提高纳米铋粉的产量和产率。在本试验条件下，制备纳米铋粉的优化参数为铋粒加入量取0．06mol，复合修饰剂与铋粒的质量比为1：3，转速取250r／min，时间为4h。     

溶剂萃取法制备纳米铜均匀分散的植物型绿色润滑油

采用溶剂萃取法在油相中以水合肼为还原剂还原醋酸铜,将十二烷基苯磺酸钠作为修饰剂以制备纳米铜均匀分散的植物型绿色润滑油。采用傅立叶变换红外光谱仪和扫描电镜表征修饰的纳米铜材料。采用MQ-800型四球摩擦磨损试验机考察了纳米铜均匀分散的绿色润滑油的摩擦学性能。实验结果表明,纳米铜能明显改善植物型绿色润滑油的性能,提高最大无卡咬负荷,采用溶剂萃取法制备的纳米铜均匀分散的植物型绿色润滑油能长时间稳定保存。     

纳米TiO_2敏感膜修饰的QCM气体传感器检测氨气的研究

主要介绍了纳米TiO2修饰的QCM(Quartz Crystal Microbalance)气体传感器的制备与测试。在石英晶振片表面制备纳米TiO2敏感膜,构成QCM氨气传感器。检测系统为自主研发的基于LabVIEW平台的QCM气体传感器频率测试软件。检测氨气的体积分数为1×10-5~5×10-5,响应时间均在10 s以内,响应最大频差值与氨气浓度呈现良好的线性关系,相关系数为0.999 4。室温条件下,纳米TiO2敏感膜可以完全实现吸附解吸过程,具有可逆性。该传感器性能稳定,响应灵敏,具有重复性。     

不同极性基团表面修饰剂对纳米氟化镧摩擦学性能的影响

以不同极性基团的十八酸二乙醇胺、双β羟乙基十八胺及二辛基二硫代磷酸二乙醇胺为表面修饰剂,在醇-水体系中制备了3种纳米氟化镧粒子,通过透射电镜（TEM）及热重仪（TG）研究了纳米氟化镧粒子的形貌及表面修饰情况,采用离心沉降法考察了纳米粒子在基础油中的分散稳定性,用四球机考察了它们的摩擦学性能,最后采用扫描电子显微镜（SEM）和俄歇电子能谱仪（AES）分析了磨痕表面。结果表明：二烷基二硫代磷酸胺盐修饰的纳米粒子粒径更小,更均匀。表面修饰剂极性基团同无机纳米核强的化学作用且极性基团具有多长侧链更有利于纳米粒子在基础油中分散稳定。含牺牲性润滑元素硫和磷的表面修饰剂纳米粒子因极压膜的生成而有更好的极压抗磨性能。表面修饰剂的亲油链越长越有利于发挥纳米粒子的减摩作用。     

MoS2的表面修饰与摩擦学性能研究

分别用油酸（OA）、司班-60（Span-60）、十六烷基三甲基溴化铵（CTAB）-二烷基二硫代磷酸吡啶盐（Py-DDP）对MoS2纳米微粒进行表面修饰，考察了修饰后微粒的形貌、在液体石蜡中的分散稳定性和润滑性能，并采用四球摩擦磨损机测试了其摩擦学性能。结果表明，选用不同修饰剂所得到的修饰MoS2纳米微粒的稳定性和摩擦学性能均有不同程度的提高，其中以CTAB—PyDDP修饰MoS2纳米微粒的分散稳定性更佳，摩擦学性能最好。     

表面修饰FeS纳米微粒的研究（Ⅰ）——合成及表征

采用表面修饰的方法，以双十八烷基二硫代磷酸盐（DDP）为表面修饰剂，制备了双十八烷氧基二硫代磷酸（DDP）表面修饰的FeS纳米微粒。采用TEM，DSC，XRD和FT-IR对表面修饰FeS纳米微粒进行结构分析。结果表明：表面修饰FeS纳米微粒是由DDP表面修饰层和FeS纳米核心所构成，微粒尺寸在4—6nm之间。DDP表面修饰FeS纳米微粒在氯仿、苯和甲苯等有机溶剂中都具有良好的分散性。     

纳米TiO2/ATP复合光催化剂的合成及其表征

以凹凸棒石黏土（Attapulgite，缩写为ATP）为载体，通过酸性溶胶法制备纳米Tio2／ATP前驱体，再经过高温煅烧得到其复合体。利用X射线衍射（XRD）、扫描电镜（SEM）、差热（DTA-TG）手段对其组成、尺寸、结构等进行分析和表征。结果表明，该复合光催化剂中的纳米TiO2在凹凸棒石黏土表面分布均匀，TiO2纳米颗粒间不发生团聚，TiO2粒径比相同工艺获得的纯TiO2小。     

硅油基纳米Fe_3O_4磁性液体的制备

采用化学共沉淀法,成功制备了纳米Fe3O4微粒,主要研究了Fe2+与Fe3+不同物质的量比对Fe3O4微粒、粒径及磁化强度的影响,采用不同表面活性剂制备了硅油基纳米Fe3O4磁性液体。结果表明:Fe2+与Fe3+物质的量比对Fe3O4微粒性能影响显著,对微粒尺寸影响不大,均为纳米级,当Fe2+与Fe3+物质的量比为0.6时,其饱和磁化强度达到最大,为52.1 A.m2.kg-1;在无水乙醇中,聚乙烯吡咯烷酮(PVP)的分散效果虽优于油酸,但与硅油相溶性差、增粘作用明显的缺点限制了PVP的使用;而油酸由于亲油性好,更适合作为制备硅油基Fe3O4磁性液体的表面活性剂。     

Fe^（3＋）掺杂TiO2的制备、表征与光催化性能研究

以空心玻璃微球（GMBs）为载体,钛酸四丁酯（Ti（OC4H9）4）为原料,采用浸涂法制备可漂浮附载型复合光催化剂Fe-TiO2/GMBs。样品的结构、成分、形貌和核壳厚度分别用X射线衍射仪（XRD）、X射线能谱仪（EDS）和场发射扫描电子显微镜（FESEM）进行表征。并研究样品在紫外光照射下催化降解罗丹明B（RhB）的性质。结果表明,Fe元素的存在既没有影响TiO2由锐钛矿相向金红石相转变,也没有增加新的晶相,而是使TiO2的光催化活性明显增强,本文对TiO2光催化机理也进行讨论。     

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。     

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.     

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....     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.