Feedback spreading control laws for semilinear distributed parameter systems

The paper shows, for the first time that a feedback spreading control law for semilinear distributed parameter systems with compact linear operator can be provided by a selection procedure which involves both the dynamics of the system and the property to be spread. In the case of affine dependence upon the control a minimum energy feedback spreading control law will be derived by using a parametrized constrained optimization technique along with some facts of set-valued analysis.     

钴对Ag—Cu—Pd合金钎料性能的影响

研究结果表明,在Ａｇ－Ｃｕ－Ｐｄ合金钎料中添加０．２－１．０ｗｔ％Ｃｏ后,对钎料的物理性能,电学性能以及力学性能无明显影响,但对ＢＡｇ６５ＣｕＰｄ钎料在某些母材上过度的铺展性确有显著地抑制作用,Ａｇ６５Ｃｕ２０Ｐｄ１５－ｘＣｏｘ钎料可以部分地取代电子器件中的金基纤料。     

Peanut skins-fortified peanut butters: Effects on consumer acceptability and quality characteristics

Peanut skins (PS), high phenolics by-products from peanut processing, are potential functional ingredients. Effects of fortification with ground PS (3 types: dry-blanched, light- and medium-roasted) on peanut butter (PB) quality characteristics and consumer acceptability were evaluated. PS were added in concentrations of 0 (control), 2.5 and 5.0 g PS/100 g PB. Data were analyzed with Mixed Model ANOVA. Significant effects (P < 0.05) on product appearance and physical characteristics depended on level of incorporation and type of skins used; the greatest impact on objective appearance (L*, a*, b* color and particulate presence) and instrumental physical properties (spreadability and texture profile analysis parameters) occurred with incorporation of 5.0 g medium roasted PS/100 g PB. Consumer sensory panelists (P < 0.05) noted an increase in stiffness with incorporation of roasted PS at both levels, and less acceptable spreadability with incorporation of 5.0 g light or medium-roasted PS/100 g PB when compared to the control. Panelists also found PS addition affected acceptability of appearance more than flavor, texture or overall acceptability. With incorporation of 2.5 g PS/100 g PB, PS addition produced PBs that equaled the control in overall acceptability, regardless of heat treatment. At the 5.0 g PS/100 g PB incorporation level, PBs containing medium-roasted PS were less acceptable (P < 0.05) than all other formulations.     

2000年问题的技术解决方案

社会对计算机的依赖到达如此程度，以至于要花6000亿美金去解决40年前只需100美金就能解决的2000年问题，计算机2000年问题已是一个社会问题，但解决问题的手段是技术性的。     

松香树脂对SnAgCu焊膏性能的影响

通过焊膏回流焊接铺展性能及其抗塌落能力测试分析.研究了助焊剂中氢化松香和聚合松香的总含量以及它们的复配比例对SnAgCu焊膏性能的影响.结果表明:当助焊剂中松香质量分数在20%～60%的范围时,增加松香含量可提高焊膏的铺展性能,改善焊点形貌,并显著增强抗塌落能力.当助焊剂中松香总质量分数为40%时,不同松香复配比例的焊膏铺展试验均表现出焊点饱满、表面光亮、周边规则的特征,铺展率基本相当,约为82%,而焊膏的抗塌落性能随聚合松香比例提高而提高.元件试焊表明焊膏具有良好的焊接性能,可用于一般电子产品的焊接.     

Spreadability and vulnerability of distributed parameter systems

In this article we focus on the mathematical development of vulnerability concept and vulnerability index and analyze the dependence of the vulnerability concept definition on that of spreadability [A. El Jai and K. Kassara, “Spreadable distributed systems”, Mathem. and Comp. model., 20, pp. 47--64, 1994; A. Bernoussi and A. El Jai, “New approach of spreadability”, Journal of Mathematical and Computer Modelling 31, pp 93--109, 2000; A. Bernoussi, A. El Jai and A. J. Pritchard, “Spreadability and evolving interfaces”, Inter. J. Syst. Sci., 32, pp. 1217--1232, 2001]. It is found that the mathematical approach of the vulnerability concept is rather attractive and can be applied to many engineering problems. To illustrate this, some examples and applications are considered.     

Experimental investigation on the spreadability of cohesive and frictional powder

Spreadability of cohesive and frictional powder is critical in powder spreading of additive manufacturing. Different to flowability, the experimental test techniques and underlying powder mechanics of spreadability have not yet been thoroughly acknowledged. In this work, the effects of operation conditions and particle properties on the spreadability of metal powder are experimentally investigated. A measure of relative spreadability based on D₉₀ is proposed, considering the effect of size classes of powder. The results show that the spreadability is a non-monic function of the spreading speed, and there is an optimal spreading speed. A concept of dynamic spreadability is also proposed to consider the demand of a high manufacturing rate in AM. The spreadability is strongly affected by the detachment of particles from the heap and the re-filling process of the depletion region. Excellent spreadability could only be obtained in a specified range of flowability, where the powder should neither extremely cohesive nor excessively free-flowing with little frictional resistance.     

人造奶油常见缺陷及对策

从外观、口感及涂抹性能３方面描述了人造奶油常见的缺陷及其原因，并针对这些缺陷提出了相应的解决办法。     

(AgCu28)80InxSn(20-x)焊料合金的显微组织与性能

通过微合金化的方法,采用XRD、SEM/EDS、DSC和铺展性分析等测试手段研究了不同In、Sn添加量的(AgCu28)80InxSn(20-x)焊料合金的显微组织、熔化特性和铺展性能.结果表明:(AgCu28)80In11Sn9合金具有较低的固相线温度和熔程、简单的物相结构、适中的铺展率.其综合性能在添加11%的In时最好.