CAN总线在粮情测控系统中的应用

现场总线的发展与应用引起了传统控制系统结构的改变,CAN总线因其自身的特点被广泛应用于自动控制领域。本文介绍了一种基于CAN总线的粮情测控系统,给出了系统的总体结构,并对系统的硬件配置和软件功能作了详细的说明。实际应用表明本系统具有结构简单、可靠性高、灵活方便等优点,并且具有较好的性能价格比,有着广泛的应用前景。     

Texture development and dielectric relaxor behavior of 0.80Na0.5Bi0.5TiO3–0.20K0.5Bi0.5TiO3 ceramics templated by plate-like NaNbO3 particles

Plate-like NaNbO₃ particles were used as templates to fabricate grain-oriented 0.96(0.8Na_0.5Bi_0.5TiO₃–0.2 K_0.5Bi_0.5TiO₃)–0.04NaNbO₃ (NKBT) ceramics. The effects of the sintering temperature and the soaking time on the grain orientation and the microstructure of the textured NKBT ceramics were investigated, and the dielectric relaxor behavior is discussed. The results show that textured ceramics were successfully obtained with orientation factor more than 0.8. The textured ceramics have a microstructure with strip-like grains aligning in the direction parallel to the casting plane. The degree of grain orientation increases initially, then decreases with increasing sintering temperature, and increases continuously with increasing soaking time. The textured NKBT ceramics shows obvious dielectric relaxor characteristics which can be well explained by microdomain–macrodomain transition theory with calculating criterion K. The results show that formation of texture is beneficial to microdomain–macrodomain transition, which lead to weaken relaxor behavior and raise the dielectric constant at T_tr.     

Dehydration by Successive Pressure Drops for Drying Paddy Rice Treated by Instant Controlled Pressure Drop

The aim of the present work was to study the application of the dehydration by successive pressure drops (DDS) process to different varieties of paddy rice initially treated by the instantaneous controlled pressure drop (DIC), which is a high-temperature, short time postharvest treatment (moisture content about 20–25% dry basis) and takes less than 30 s. DIC paddy rice is dried by DDS in a relatively short time and a high milling quality is obtained (12–13% db in about 2 h). The final rice is white, easily distinguishing it from the standard parboiled one. Without a tempering period, DDS rice has less than 3% of broken grains, with a high organoleptic quality (preservation of the natural aroma with a firm and non-sticky texture), and the cooking time of both brown (whole) and white DIC rice is very short (15 and 7 min, respectively).     

Dielectric relaxation behavior and energy storage properties in Ba0.4Sr0.6Zr0.15Ti0.85O3 ceramics with glass additives

Ba_0.4Sr_0.6Zr_0.15Ti_0.85O₃ ceramics with SrO–B₂O₃–SiO₂ glass additives were prepared via the solid state reaction route. The effects of glass contents on the sintering behavior, dielectric properties, microstructures, and energy storage properties of BSZT ceramics were investigated. Dielectric breakdown strength of 22.4 kV/mm was achieved for BSZT ceramics with 20 wt% glass addition. Dielectric relaxation behavior was observed in dielectric loss versus temperature plots. In order to investigate the mechanism of dielectric breakdown performance, the relationship between dielectric breakdown strength and grain boundary barrier was studied by the measurements of breakdown strength and activation energy. A discharged energy density of 0.45 J/cm³ with an energy efficiency of 88.2% was achieved for BSZT ceramics with 5 wt% glass addition.     

Soybean Drying by Two-Dimensional Spouted Bed

Abstract

Urease activity, cracking, and breakage are important factors in considering the quality of raw soybean for feed meal industries. A two-dimensional spouted bed dryer was investigated to determine its capability for thermally inactivating the urease enzyme and maintaining its other qualities. The experimental results have shown that the drying kinetics of soybean in a two-dimensional spouted bed dryer are of the form described in the thin layer drying. The expression for the model parameter in Newton's law of cooling equation accounting for the moisture contents and inlet air temperatures was developed. The initial moisture content and inlet air temperature conditions cause cracks in the kernels. The strong collision between kernels and deflector because of high superficial velocity leads to high percentage of broken soybeans in the spout region. However, the velocity of 15.9 m/s can reduce the breakage below 5%. The inactivation of urease at low-to-moderate moisture content is suitably described by the first order kinetics. The modified Monod equation is applied when the moisture content is higher than 26% dry basis due to the inhibitory effect of water content on the inactivation rate. To complete urease inactivation and maintain protein quality, the temperatures of 150°C should be used.     

硅质耐火泥施工性能的探讨

探讨了硅质耐火泥施工性能的具体要求,根据现有的国家技术标准进行样品试验,对原料的粒度配级和施工性能赋予剂上进行研究。最终得出结论,合理的粒度级配是焦炉用硅质火泥获得优良的施工性能的基础。必须添加水溶性有机物和无机盐组合添加剂,才能使火泥获得良好的施工性能。     

Microstructure of Ba1−xLaxTiO3−δ ceramics sintered by Spark Plasma Sintering

Nano-sized Ba_1−xLa_xTiO₃ (0.00 ≤ x ≤ 0.14) powders were prepared by a coprecipitation method and calcined at 850 °C in air. The corresponding ceramics were obtained by Spark Plasma Sintering (SPS) at 1050 °C. These ceramics are oxygen deficient and are marked as Ba_1−xLa_xTiO_3−δ. Both powders and ceramics were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The effect of lanthanum concentration on the densification behavior, on the structure and the microstructure of the oxides was investigated. Average grain sizes are comprised between 54 (3) nm and 27 (2) nm for powders, and 330 (11) nm and 36 (1) nm for ceramics according to the La-doping level. Powders crystallize in the cubic (or pseudo-cubic) perovskite phase. The structure of ceramics consists in a mixture of cubic (or pseudo-cubic) and tetragonal perovskite type phases. As the lanthanum content increases, the tetragonality of the samples decreases, as well as the grain size.     

连续铸挤Al-5Ti-1B合金线的组织与晶粒细化效果

采用连续铸挤成形Al-5Ti-1B合金线,采用光学显微镜和扫描电镜分析了Al-5Ti-1B合金线的显微组织和晶粒细化效果,并与A1-5Ti-1B合金锭进行了比较.结果表明,连续铸挤 Al-5Ti-1B合金线中TiAl3 相呈细小圆块状,分布均匀,TiB2粒子弥散分布于铅基体;而Al-5Ti-1B合金锭中TiA13相呈粗大板条状,TiB2 粒子偏聚于铝晶界呈粗大团块状.Al-5Ti-1B合金线对纯铝的晶粒细化效果优于Al-5Ti-1B合金锭,纯铝加入A1-5Ti-1B合金线5 min后,晶粒尺寸达到最小.     

Al-Ti、Al-Ti-C中间合金对AZ91D镁合金组织和性能的影响

研究了Al-5Ti、Al-5Ti-0．25C和Al-8Ti-2C中间合金对AZ91D镁合金的组织、力学性能和耐腐蚀性能的影响。结果表明,添加Al-5Ti中间合金使晶粒粗化,而添加Al-5Ti-0．25C和Al-8Ti-2C中间合金使晶粒细化,Al-8Ti-2C中间舍金的细化效果明显且细化后组织细小均匀;添加Al-5Ti中间合金使合金的力学性能降低,而添加Al-5Ti-0．25C和Al-8Ti-2C中间合金均使合金的拉伸强度和伸长率得到了提高;添加Al-5Ti、Al-5Ti-0．25C和Al-8Ti-2C中间合金均使合金的耐腐蚀性能得到了改善。对于AZ91D合金而言,Al-8Ti-2C中间合金是一种良好的晶粒细化剂。     

等通道转角挤压(ECAP)工艺的研究现状

等通道转角挤压(ECAP)是一种大塑形加工技术,可细化合金组织,改善性能,提高材料的成形性.本文概述ECAP法的基本原理、剪切模式与变形规律,分析摩擦因素对变形的影响,综述中国在ECAP合金组织、性能方面的一些研究成果.