集成电路封装陶瓷外壳埋线电阻的设计

本文介绍了集成电路封装外壳埋线电阻的设计方法以及在工艺上如何应用浆料配比、间隙填充、通孔穿层等途径来降低外壳埋线电阻值。     

A measure of bullwhip effect in supply chains with a mixed autoregressive-moving average demand process

In this paper, we quantify the impact of the bullwhip effect – the phenomenon in which information on demand is distorted as moving up a supply chain – for a simple two-stage supply chain with one supplier and one retailer. Assuming that the retailer employs a base stock inventory policy, and that the demand forecast is performed via a mixed autoregressive-moving average model, ARMA(1, 1), we investigate the effects of the autoregressive coefficient, the moving average parameter, and the lead time on the bullwhip effect.     

Matroids on convex geometries (cg-matroids)

We consider matroidal structures on convex geometries, which we call cg-matroids. The concept of a cg-matroid is closely related to but different from that of a supermatroid introduced by Dunstan, Ingleton, and Welsh in 1972. Distributive supermatroids or poset matroids are supermatroids defined on distributive lattices or sets of order ideals of posets. The class of cg-matroids includes distributive supermatroids (or poset matroids). We also introduce the concept of a strict cg-matroid, which turns out to be exactly a cg-matroid that is also a supermatroid. We show characterizations of cg-matroids and strict cg-matroids by means of the exchange property for bases and the augmentation property for independent sets. We also examine submodularity structures of strict cg-matroids.     

Parametrized spaces model locally constant homotopy sheaves

We prove that the homotopy theory of parametrized spaces embeds fully and faithfully in the homotopy theory of simplicial presheaves, and that its essential image consists of the locally homotopically constant objects. This gives a homotopy-theoretic version of the classical identification of covering spaces with locally constant sheaves. We also prove a new version of the classical result that spaces parametrized over X are equivalent to spaces with an action of ΩX. This gives a homotopy-theoretic version of the correspondence between covering spaces and π₁-sets. We then use these two equivalences to study base change functors for parametrized spaces.     

Direct synthesis of amino-functionalized monodispersed mesoporous silica spheres and their catalytic activity for nitroaldol condensation

New amino-functionalized monodispersed mesoporous silica spheres (MMSS) were synthesized directly by co-condensation of 3-aminopropyltrimethoxysilane (AP-TMS), [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAP-TMS) or 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AEAEAP-TMS) with tetramethoxysilane. By changing the methanol ratio or adding extra silica source, amino-functionalized MMSS with different particle diameter (310–780 nm) and the same mesopore size were successfully synthesized. TEM observations revealed that the mesopores were aligned radially from the center towards the outside of the spheres even in the amino-functionalized MMSS. The effect of particle diameter on base catalytic activity was investigated using the amino-functionalized MMSS. In addition, the amino-functionalized MMSS were found to be excellent base catalysts in the nitroaldol condensation reactions. The effectiveness factor was evaluated to be 0.8–0.82 and improved substantially compared with MMSS prepared by grafting method.     

便携式温场测量仪的设计与实现

温场测量是应用非常广泛的物理量测量方法。文章介绍了一种测量精度比较高的温场测量仪器的硬件设计和软件实现。阐述了温度从采集到测量、处理的各个环节;分析了影响仪器测量精度的各种因素,介绍了从软硬件方面进行处理,提高测量精度的方法。     

变频调速应用技术（六）第三讲 选好系统上变频（下）

本文介绍了能耗电路的选择和自制；变频器电路的测量问题：以及改变传动比的作用等。     

试论移动基站的交流稳压技术

简介了移动通信基站交流供电的状况及交流稳压器的市场情况，并对各种交流稳压技术进行了分析，最后给出了基站对交流稳压器的技术要求以及交流稳压器选型时应注意的几个问题。     

一种新的电阻元件等效方法及其应用

摘要：利用串联电阻的等效电阻等于各电阻之和、并联电阻的等效电导等于各电导之和的结论．导出了电阻等效的新结论,即任意电阻可以等效为一个电阻与一个电压控制电压源的串联,也可以等效为一个电阻和一个电流控制电压源的串联;任意电阻可以等效为一个电阻和一个电流控制电流源的并联,也可以等效为一个电阻和一个电压控制电流源的并联。本文给出了这种等效方法的理论证明,并以实例说明了电阻等效的应用。