Partitioned half-explicit Runge-Kutta methods for differential-algebraic systems of index 2

A class of half-explicit methods for index 2 differential-algebraic systems in Hessenberg form is proposed, which takes advantage of the partitioned structure of such problems. For this family of methods, which we call partitioned half-explicit Runge-Kutta methods, a better choice in the parameters of the method than for previously available half-explicit Runge-Kutta methods can be made. In particular we construct a family of 6-stage methods of order 5, and determine its parameters (based on the coefficients of the successful explicit Runge-Kutta method DOPRI5) in order to optimize the local error coefficients. Numerical experiments demonstrate the efficiency of this method for the solution of constrained multi-body systems.     

PIC单片机在中央空调控制器中的应用

基于PIC 16F877/16C74单片机，设计了一种能满足用户尺寸要求的中央空调控制器。     

Effect of Iron on the Color of Barley and Other Cereal Porridges

ABSTRACT: Iron added as ferrous sulfate at 500 mg*kg⁻¹ to rice, oats, whole grain wheat, or proanthocyanidin-free barley porridge caused significant changes in the Hunter "L", "a", and "b" values but the visual appearance of these porridges remained satisfactory. Porridge made with normal barley flour fortified with 500 mg*kg⁻¹ of iron developed an unappealing gray color with ferrous sulfate, ferrous fumarate, or electrolytic iron, 3 salts differing in solubility. At 100 and 250 mg*kg⁻¹ of iron, the discoloration of normal barley porridge was less pronounced, but still objectionable. When fortified with 50 mg*kg⁻¹ of iron, normal barley porridge had a slight color change but was not noticeably gray. Thus barley-containing foods can be fortified with a soluble iron compound at the level of iron used in enriched flour and similar cereal-grain foods for the general population without developing an unattractive color.     

Purification and Characterization of an Endoprotease from Melon Fruit

An endoprotease was purified from melon fruit (Cucumis melo L.) by ammonium sulfate precipitation, gel filtration and ion-exchange chromatography using t-butyloxycarbonyl-Ala-Ala-Pro-Leu p-nitroanilide as a substrate. The molecular weight was estimated as 26,000 and isoelectric point pH 9.5. It preferentially hydrolyzed peptide bonds of the carboxyl terminal sides of Leu, Ala, His, Gin, and Am. Activity was strongly inhibited by diisopropyl phosphofluoridate, indicating the serine protease nature of the enzyme. The migration distance on electrophoresis, molecular weight and substrate specificity differed from cucumisin, a known protease from melon. This unusual protease may have potential for special food treatment applications.     

A study of solid circulation rate in a circulating fluidized bed

An experimental investigation under cold condition was made to study the effects of some operating/design parameters and non-mechanical L valve configuration on the solid circulation rate in a 4.5 m tall, 0.15 m diameter circulating fluidized bed with riser flow rate varying from 1400 litres/min to 2000 litres/min and bed inventory from 15 kg to 25 kg of sand of average sizes 200 μm, 400 μm and 500 μm. Solid circulation rate was estimated by measuring velocity of sand particle travelling through a vertical Perspex tube section at the bottom of the return leg. It was found to be in the range of 2.8 to 12.3kg/m²s, 0.07 to 9.1kg/m²s and 0.12 to 2.23kg/m²s for sand sizes of 200 μm, 400 μm and 500 μm, respectively for a horizontal L valve. Two mathematical correlations have been developed from the experimental results to predict solid circulation rate as a function of riser flow rate, aeration flow rate, total bed inventory and particle size used.     

基于L298N芯片对离子渗氮中压强的控制

离子渗氮工艺对炉体内压强的控制要求比较高，本文设计了一种基于L298N芯片驱动直流电动机控制的气体流量控制器，可用于控制反应炉的抽气气体流量，提高了炉体压强控制精度，降低了生产成本。     

高速数字光电耦合器HCPL-260L/060L及其应用

HCPL-260L/060L是美国安捷伦科技有限公司推出的高速数字光电耦合器。该器件的逻辑电平与LVTTL/LVCMOS兼容 ,并具有输出使能端。文中详细介绍了HCPL -260L/060L的引脚功能、内部结构、主要特点、使用要求和注意事项 ,给出了它与LVTTL器件的典型接口电路及隔离的3.3VRS232接口电路。     

基于互信息域的L2S接口方法研究

分析了基于互信息域的有效信噪比映射的L2S(link level to system level)接口方法,研究了信道相关带宽对接口复杂度的影响,在不明显降低预测准确度的前提下,验证了利用信道相关带宽来简化接口计算复杂度的可能性。     

Anthocyanins characterization of 15 Iranian pomegranate (Punica granatum L.) varieties and their variation after cold storage and pasteurization

Anthocyanins (ACs) are phenolic compounds that are distributed widely in fruits and vegetables. Apart from imparting color to plants, ACs also have an array of health-promoting benefits. In this research, the amounts of major ACs of 15 pomegranate (Punica granatum L.) varieties obtained from Yazd province were determined. The major ACs detected in the studied varieties were as follows: delphinidin 3-glucoside (2.19–16.29 mg/L), delphinidin 3,5-diglucoside (2.36–63.07 mg/L), pelargonidin 3-glucoside (0.26–1.36 mg/L), pelargonidin 3,5-diglucoside (0.01–8.11 mg/L), cyanidin 3-glucoside (5.78–30.38 mg/L), and cyanidin 3,5-diglucoside (4.39–166.32 mg/L). The effect of storage time of unprocessed and pasteurized juices on ACs content of four selected varieties was also studied. Average degradation percentage of each AC was between 23.0 and 83.0% during 10 days at 4 °C. Moreover, in pasteurized juices average degradation of ACs was 42.8 ± 0.5% after 10 weeks storage at 4 °C.