微波在煤泥低温脱水提质的应用研究

利用微波能对煤泥低温脱水提质,探讨了微波干燥的影响因素;分析了微波干燥对煤泥性质的影响;寻求煤泥资源化利用的途径。微波时间、功率和煤泥形状、质量对微波干燥效果影响显著。在微波作用下,煤中水分的蒸发过程分三个阶段:煤加热,外在水分减少,内在水分减少,因而干燥速度较快。烘干重量为200g,水分25%的煤样所需时间不超过700s。试验表明:干燥200s后,煤样温度可达110℃;600s后,温度可达240℃。不仅蒸发了水,也排出了挥发成分。煤泥在微波低温干燥条件下具有较好的脱水效果,干燥后煤泥的含水率和热值提升幅度均达到了预期目标,证明了微波在煤泥干燥提质方面应用的可行性。煤泥微波脱水后,由于微波加热在加热物料内形成的特殊传热传质机理,煤泥内部的矿物盐等会在煤泥表面积聚,形成"硬壳",煤泥不易粉化、破碎,且水分回吸不明显,有助于后续运输和利用。     

介电特性在苹果品种识别中应用的初步探究

本文介绍利用介电特性进行水果品质检测的现状和电介质及介电特性的基本概念,并并提出基于介电特性的检测装置、测试原理,以及测试需要设置的主要参数。以苹果这一水果品种为例,对其进行了介电特性检测,测试结果表明,利用此方法进行品种识别,识别率在93%左右。     

微波干燥中介质温度梯度与含水率变化关系的研究

含水薄层多孔介质的微波干燥处理是实现长期保存的有效方法之一。本文推导了微波干燥含水薄层介质过程中温度梯度与含水率变化的关系，可以适用于多种不同材质的含水薄层多孔介质；利用多物理场仿真软件，建立了电磁场、温度场及速度场的耦合模型，仿真了薄层多孔介质在微波干燥过程中温度梯度与含水率变化的关联关系。选取黄豆作为薄层多孔介质样本进行微波干燥的实验，测量其在微波干燥过程中温度梯度变化和含水率变化的关系及不同干燥阶段对黄豆发芽率的影响。实验结果表明黄豆在微波干燥过程中，温度梯度与干燥程度存在固定关系，通过控制梯度趋于0时的干燥时间可以达到设定的干燥程度，并且对其发芽率影响较小。     

包裹A1_2O_3对BaTiO_3基陶瓷性能的影响

采用固相法制备掺杂有稀土元素Nd和Y的BaTiO3基陶瓷粉体,在该粉体表面包裹A12O3。研究了包裹A12O3对BaTiO3基陶瓷的微观结构、微观形貌、介电性能、击穿电压和介电非线性的影响。结果表明:包裹A12O3后,BaTiO3基陶瓷的相对介电常数达到4000,绝缘电阻率达到1011?.cm,耐压提高到20×103V/mm,介电非线性得到改善,有望在储能领域中得到应用。     

利用冻干技术开发蔬菜及畜禽水产品出口

1　什么是冻干食品随着食品的冷藏处理量日趋增长 ,且其复杂的分销系统以及病菌易混入等缺点 ,使人们需求一种不需冷藏 ,更易保存且又能长时间保鲜的方法 ,真空冷冻干燥技术迎合了这种需求。将经过前处理的物料 (菜、肉、药材等 )速冻后 ,在真空条件下使其中的水分由固态冰升华成气 ,从而使物料脱水干燥 ,这就是真空冷冻干燥 ,简称冻干。冻干技术可加工、蔬菜、水果、鱼肉、方便面食品、调味品、茶叶、速溶咖啡、酶素、菌种、生物制品等。冻干食品生产线以JDC型为例 ,主要包括前处理、速冻、升华干燥和包装等环节。为了给速冻库和升华干燥…     

成型压力对CuFeO_2陶瓷材料结构和介电性能的影响

采用传统固相反应法在不同成型压力下(10~800 MPa)制备系列CuFeO_2陶瓷样品,利用X-射线衍射(XRD)、扫描电子显微镜(SEM)和阻抗分析仪等技术手段对陶瓷样品的晶体结构、微观形貌和介电性能进行测试和表征。实验结果表明,实验成型压力范围内体系未发生结构相变,但成型压力对其微观形貌有较明显的影响。成型压力为100 MPa时,样品的晶粒得到充分生长,晶粒尺寸最大,且晶界清晰。电性能测试结果表明,适当的增加成型压力可提高体系的介频稳定性;成型压力为100 MPa时,样品具有较高的介电常数和较低的介电损耗,显示出良好的介电性能。对CuFeO_2陶瓷样品的微观结构与介电性能的关联规律进行了初步解释。     

Bi_2O_3掺入对CLST微波介质陶瓷性能的影响

研究了Bi2O3掺入对CaO-Li2O-Sm2O3-TiO2(简写为CLST)系微波介质陶瓷介电性能的影响。用XRD和SEM研究其晶体结构及微观形貌。结果表明:Bi2O3掺入能显著降低CLST陶瓷的烧结温度,由1300℃降至1200℃,1200℃烧结2h后,仍形成了斜方钙钛矿结构,但原有金红石相消失。掺入5%(质量分数)Bi2O3的CLST陶瓷取得了较好的介电性能:εr为93,tanδ为0.0078,τf为–29×10–6℃–1。     

湿法成型坯件的干燥工艺

<正> 湿法成型的陶瓷坯件含水率较高,若要提高产品合格率,必须确定合理的干燥工艺制度。 水分从泥坯中蒸发的速度取决于温度和湿度,所以干燥过程不仅与升温曲线有关,还与各温度区间的空气相对湿度有关。烘房的设计若只考虑温度梯度的控制而忽略对相     

飞秒激光制备超疏水铜表面及其抗结冰性能

超疏水表面的制备及其抗结冰性能受到广泛关注,但超疏水表面的微观结构及浸润性能对其抗结冰性能的影响规律仍无定论。利用飞秒激光在金属铜表面制备了一系列具有不同微观特征的微纳米结构,这些表面经过化学修饰后都具有超疏水性,同时对水具有不同的粘附性。系统研究了这些超疏水表面的抗结冰性能,结果表明,这些超疏水表面在低温(-5℃,-10℃)下都能延缓表面水滴的结冰过程。超疏水表面对水的粘附性对其抗结冰性能有显著影响,粘附性较小的超疏水表面比高粘附的超疏水表面具有更为优异的抗结冰性能。     

富Li对LiZn铁氧体微观结构和磁电性能的影响

采用氧化物陶瓷工艺,按组分Li0.35+xZn0.3Mn0.06Fe2.29O4+δ+2%Bi2O3(x=0~0.180)在1 000℃下制备LiZn铁氧体,研究了不同富Li量对LiZn铁氧体微观结构、磁性能和介电性能的影响。结果表明,当富Li量x≤0.015时样品断面的微观形貌变化不大,晶粒均匀致密,而x≥0.045时,气孔和缺陷增多,晶粒尺寸减小;随着富Li量的增加,饱和磁化强度和剩磁比先略微增大后明显减小,矫顽力呈先缓慢后迅速增大趋势,而电阻率单调上升,介电损耗先下降后上升。当x=0.045时,LiZn铁氧体微观结构和磁性能较好,介电损耗角正切下降至5.25×10-4。     

全光纤微型土壤水分含量传感器

基于掺杂光纤光热转换效应和光纤光栅测温原理研发了一种全光纤微型土壤水分含量传感器。利用1480 nm泵浦激光对埋设在土壤中的掺钴光纤加热，同时利用刻写在掺钴光纤上的布拉格光栅测定其温度变化，根据加热过程中温度特征值与含水率之间存在的线性关系实现土壤水分含量的原位测量。为了验证该方法的可行性和传感器准确度，搭建了土壤水分含量测试平台并进行实验，实验表明温度特征值与土壤含水率之间存在线性关系；且研发的全光纤微型土壤水分含量传感器所测土壤含水率与烘干法有较好的一致性，最大误差?1.41%，明显优于电导率法。这种新型的土壤水分含量测量方法具有微型化、低功耗的特点。     

The NAFE'05/CoSMOS Data Set: Toward SMOS Soil Moisture Retrieval, Downscaling, and Assimilation

The National Airborne Field Experiment 2005 (NAFE'05) and the Campaign for validating the Operation of Soil Moisture and Ocean Salinity (CoSMOS) were undertaken in November 2005 in the Goulburn River catchment, which is located in southeastern Australia. The objective of the joint campaign was to provide simulated Soil Moisture and Ocean Salinity (SMOS) observations using airborne L-band radiometers supported by soil moisture and other relevant ground data for the following: (1) the development of SMOS soil moisture retrieval algorithms; (2) developing approaches for downscaling the low-resolution data from SMOS; and (3) testing its assimilation into land surface models for root zone soil moisture retrieval. This paper describes the NAFE'05 and CoSMOS airborne data sets together with the ground data collected in support of both aircraft campaigns. The airborne L-band acquisitions included 40 km times 40 km coverage flights at 500-m and 1-km resolution for the simulation of a SMOS pixel, multiresolution flights with ground resolution ranging from 1 km to 62.5 m, multiangle observations, and specific flights that targeted the vegetation dew and sun glint effect on L-band soil moisture retrieval. The L-band data were accompanied by airborne thermal infrared and optical measurements. The ground data consisted of continuous soil moisture profile measurements at 18 monitoring sites throughout the 40 km times 40 km study area and extensive spatial near-surface soil moisture measurements concurrent with airborne monitoring. Additionally, data were collected on rock coverage and temperature, surface roughness, skin and soil temperatures, dew amount, and vegetation water content and biomass. These data are available at www.nafe.unimelb.edu.au.     

Particle-free wafer cleaning and drying technology

It is reported that an NH₄OH-H₂O₂ solution is excellent for removing particulate contaminants from VLSI silicon wafers after chemical solution treatment. The ratio of NH₄ OH in the solution can be reduced down to 1/10 of the standard ratio while keeping high removal efficiency. By decreasing the NH₄ OH content, wafer damage which appears as a so-called haze during the NH₄OH-H₂O₂ treatment is reduced. To establish a particle-free wafer drying system, a particle-generation-free isopropanol (IPA) vapor drying system has been developed. By eliminating all possible particle generation sources from the drying system, ultraclean wafer drying equipment has been realized. A number of parameters to be controlled have been thoroughly investigated. Three were found to seriously influence surface cleanliness after drying: the water content in the IPA, temperature distribution around the wafers, and the IPA vapor velocity. The optimum drying conditions in which high quality of wafer surface cleanliness can be realized were confirmed experimentally     

多孔硅新的表面处理技术

对多孔硅施加阳极氧化表面处理技术,可有效解决多孔硅干燥时出现龟裂及坍塌，破坏原有多孔硅的形貌和本质的问题．阳极氧化表面处理技术就是使用少量的负离子作用于多孔硅表面，满足SI分子化合价的需要,消除悬空键,促使多孔硅表面性能稳定，避免结构重组产生分子间的不均匀内应力，从而获得性能稳定、可靠、在空气中可以长期干燥保存的多孔硅．     

气密性金属封装内的水汽及气氛研究

从封装管壳、贴片材料、固化烘烤处理方式等方面,研究了封装内部的水汽和气氛。结果表明,管壳清洗后烘焙的水汽含量低于清洗后不烘焙的水汽含量。粘结材料(环氧树脂、氰酸酯树脂等)吸附于器件表面,其排放对封装内的水汽有严重的影响。对于环氧树脂H35和氰酸酯树脂JM7000两种导电胶,烘焙后的效果要好于未烘焙,且随着烘焙时间的延长,水汽含量逐步降低。对外壳清洗后进行150℃/8h的烘焙,对水汽和气氛都有好处。由于储能焊对导电胶的热冲击不大,两种导电胶的水汽和气氛排放并无明显差别。     

A method of the measurement of moisture in IC packages using microwaves

A new method to measure the moisture content of integrated circuit (IC) packages is demonstrated. The moisture contained in the encapsulant resin was determined by using microwaves. The microwave signal was transmitted into the encapsulant resin and reflected at the surface of the chip pad. The amplitude and phase of the reflection coefficient of the microwave signal, which varied with the moisture content of the encapsulant resin, were measured in order to determine the moisture content. A preliminary experiment was carried out, and the calibration equation was developed. The present technique indicates the possibility of determining the moisture content directly without drying and weighing IC packages.     

8031单片机在绝缘材料真空干燥中的应用

准确测定电工绝缘材料真空干燥过程中的含水量,并实现实时在线控制,在绝缘材料真空干燥工艺中具有重要的实践意义,本文论述以8031单片机为核心的微机系统对电工绝缘材料真空干燥过程中水分含量进行了实时在线监测的方法,并给出了硬件结构框图及软件流程图。     

真空干燥参数对TFT栅极光刻性能的影响

液晶显示器薄膜晶体管(TFT)的栅极需经光刻工艺制得.在光刻工艺中,除曝光与显影环节外,光刻胶显影后的关键尺寸(DICD)和锥角(Taper)还受到真空干燥参数的影响.为此,文章以干燥制程的慢抽时间、保压时间和底压为自变量,DICD和Taper为因变量,采用全因子实验,研究了真空干燥制程对光刻胶DICD和Taper的影响.结果表明:慢抽时间和底压产生的影响较小,保压时间则是关键参数:随着保压时间增加,DICD增加、Taper降低.这是因为随着保压时间增加,光刻胶中的溶剂挥发总量增加,光刻胶更致密,显影速度下降,导致DICD增加;同时,光刻胶顶部溶剂挥发量增加,顶部感光剂浓度增加,导致顶部侧向显影程度增加,最终造成光刻胶Taper下降.此外,建立了 DICD和Taper与保压时间的回归方程,可以预测光刻效果,或者由预期的光刻效果反推出所需的保压时间.此工作可为薄膜晶体管光刻产线的参数优化和产品良率提升提供参考.     

Moisture assessment in transformers including overloading limits

Summary  A moisture model determines the moisture distribution in cellulose and oil. The model focuses on oil flow, moisture vapour pressure and the saturation properties of oil and cellulose. Measurements of material properties form the basis of each computation model. Direct measurements were performed. Samples of paper and pressboard were aged in oil. The measurements of moisture absorption were performed in air. For given moisture content the moisture vapour pressure reaches lower values than in previous results. Consequently, moisture values in oil reach lower values and the risk of bubbling at rising temperatures reduces. It has, for the first time, been established that bubbling requires a contribution of dissolved gas like air to reach critical vapour pressure levels to obtain bubbling at 150 °C hotspot and with 3% average moisture content and 1.2% in the hotspot respectively. Here oil must absorb on atmosphere air at 70 °C. Without dissolved gas an average moisture content of 4% and a hot spot temperature of about 165 °C would be necessary to come close to a risky condition. The low tendency to bubbling is also favoured by the reduced moisture content in the winding hotspot insulation which is caused by the temperature distribution due to axial oil gradient and winding gradient. The general calculation for individual spots in the transformer insulation like the hotspot is based on the moisture vapour pressure of cellulose and oil as the driving force of moisture migration. The axial temperature distribution, however, generates an axial gradient of moisture vapour pressures in oil. The cellulose insulation reaches the moisture pressure level of its neighbouring oil. The average cellulose moisture content provides basic information about the moisture condition. The calculation model is required to determine the moisture values in a transformer under operation conditions. Aging and bubbling considerations are based on the moisture content of the hotspot. Filling of a transformer with oil often happens at a moisture content of 5 ppm. At low temperatures and slow moisture diffusion into the bulk material the cellulose surface can develop extremely high moisture values. Therefore, a high temperature during filling is recommended. Furthermore, a transformer can, in principle, absorb moisture from the atmosphere or vice verse. The direction of migration is determined by the difference of local moisture vapour pressure between oil and atmosphere which depends on temperature and moisture. The slow migration velocity at low temperatures and tightness of the tank limits the value to below 7% moisture content in cellulose.