Proximity in concave integer quadratic programming

Mathematical Programming - A classic result by Cook, Gerards, Schrijver, and Tardos provides an upper bound of $$n \Delta $$ on the proximity of optimal solutions of an Integer Linear Programming...     

分类问题的在线顺序双并联快速学习机

双并联前馈神经网络模型是单层感知机和单隐层前馈神经网络的混合结构,本文构造了一种双并联快速学习机算法,与其他类似算法比较,提出的算法能利用较少的隐层单元及更少的待定参数,获得近似的学习性能.数值实验表明,对很多实际分类问题,提出的算法具备更佳的泛化能力,因而可以作为快速学习机算法的有益补充.     

无人机健康诊断知识库建立研究

针对无人机健康诊断系统的设计,研究了健康诊断专家知识库的建立方法。介绍了基于规则的专家知识库的含义及其对无人机设计的要求,阐述了故障树与故障模式判据表的形成方法。故障树分析基于故障因果逻辑,逐层找出故障事件的原因,保证专家知识逻辑上的完备性。故障模式判据表将抽象的专家知识具体化为多个能够在工程上应用的要素。提出了一种故障树分析与故障判据规则相结合的建立健康诊断专家知识库的方法。从某型大气数据系统的组成及原理出发,以大气数据系统真空速失效为顶事件,构造了故障树和故障模式判据表。结果表明,结合故障树和故障模式判据表格构造的专家知识库清晰、简洁,具有很高的工程实用价值,能够应用于无人机健康诊断系统的设计。     

偶联酶催化分光光度法测定黄嘌呤

研究了以黄嘌呤氧化酶-辣根过氧化物酶-苯酚-4-氨基安替比林反应为显色体系测定不同样液中黄嘌呤浓度的新方法。确定该测定方法的最佳反应条件为:黄嘌呤氧化酶(XO)0·32U/mL,辣根过氧化物酶(HRP)7·0U/mL,4-氨基安替比林(AAP)1mmol/L,苯酚(PA)6mmol/L溶于100mmol/LTris-HCl缓冲液(pH8·4);反应温度为37℃,保温时间为20min;检测波长为508nm。本方法测定黄嘌呤浓度的线性范围为0·2～10·0mmol/L,线性关系良好(R=0·9978),检测限为0·05mmol/L。方法操作简单易行,测定结果准确可靠,可有效应用于普通实验室和常规临床血液生化检测。     

关于盐在混合溶剂中的活度系数和溶剂化

李芝芬等人^[1]测定了盐在甲醇混合溶剂中的溶解度,得到经验公式: lg(S_o/S_s-kX_Ne)(1)式中S_o和S_s分别为盐在甲醇和混合溶剂中的溶解度,X_Ne为第二组分溶剂的摩尔分数,k为第二介质常数。     

Interaction between polymer and anionic/nonionic surfactants and its mechanism of enhanced oil recovery

Various experimental methods were used to investigate interaction between polymer and anionic/nonionic surfactants and mechanisms of enhanced oil recovery by anionic/nonionic surfactants in the present paper. The complex surfactant molecules are adsorbed in the mixed micelles or aggregates formed by the hydrophobic association of hydrophobic groups of polymers, making the surfactant molecules at oil-water interface reduce and the value of interfacial tension between oil and water increase. A dense spatial network structure is formed by the interaction between the mixed aggregates and hydrophobic groups of the polymer molecular chains, making the hydrodynamic volume of the aggregates and the viscosity of the polymer solution increase. Because of the formation of the mixed adsorption layer at oil and water interface by synergistic effect, ultra-low interfacial tension (～2.0?×?10^?3 mN/m) can be achieved between the novel surfactant system and the oil samples in this paper. Because of hydrophobic interaction, wettability alteration of oil-wet surface was induced by the adsorption of the surfactant system on the solid surface. Moreover, the studied surfactant system had a certain degree of spontaneous emulsification ability (D50?=?25.04?µm) and was well emulsified with crude oil after the mechanical oscillation (D50?=?4.27?µm).     

(NH4)2V7O16 Microbricks as a Novel Anode for Aqueous Lithium-Ion Battery with Good Cyclability

Searching for novel anode materials to address the issues of poor cycle stability in the aqueous lithium-ion battery system is highly desirable. In this work, ammonium vanadium bronze (NH₄)₂V₇O₁₆ with brick-like morphology has been investigated as an anode material for aqueous lithium-ion batteries and Li⁺/Na⁺ hybrid ion batteries. The two novel full cell systems (NH₄)₂V₇O₁₆||Li₂SO₄||LiMn₂O₄ and (NH₄)₂V₇O₁₆||Na₂SO₄||LiMn₂O₄ both demonstrate good rate capability and excellent cycling performance. A capacity retention of 78.61 % after 500 cycles at 300 mA g⁻¹ was demonstrated in the (NH₄)₂V₇O₁₆||Li₂SO₄||LiMn₂O₄ system, whereas no capacity attenuation is observed in the (NH₄)₂V₇O₁₆||Na₂SO₄||LiMn₂O₄ system. The reaction mechanisms of the (NH₄)₂V₇O₁₆ electrode and impedance variation of the two full cells were also researched. The excellent cycling stability suggests that layered (NH₄)₂V₇O₁₆ can be a promising anode material for aqueous rechargeable lithium-ion batteries.     

Migration-plugging properties and plugging mechanism of microfoam

To gain a better understanding of the migration-plugging properties and plugging mechanism of microfoam, micromodel tests were conducted to investigate the factors controlling the bubble size and plugging mechanism of microfoam. The resistance factor, plugging ratio, and matching factor between average bubble diameter of microfoam and pore-throat diameter of core were introduced to characterize the migration-plugging properties of microfoam by core displacement experiments. The results showed that the average bubble diameter of microfoam could be tuned from 8.6 to 57.9?µm by changing the gas liquid ratio and the sandpack foam generator permeability. Microfoam showed both better injectivity and deep plugging capacity when the matching factor was 1.35–1.87 and the gas liquid ratio was 1:2–1:1. Microfoam would create a temporary blocking zone in the high permeable region through bubble accumulation, and the subsequent microfoam would flow through the low permeable region directly or by means of elastic deformation. With the increase of the gas liquid ratio, the flow pattern of the microfoam was changed from dispersed and isolated bubbles to dense and surface contact bubbles. The blocking mode of microfoam at the pore-throat was shown to shift from intermittent plugging to continuous plugging, leading to the enhancement of plugging capacity and deformability of microfoam.     

用单块激光器和环形外腔获得稳定的532 nm激光

采用单块半非平面Nd:YAG单频环形激光器和环形外腔倍频技术，获得了单频功率249.5mW的532nm波长的绿光输出，倍频效率43.2%，实现了倍频腔与激光器之间的跟踪锁定，倍频光功率稳定性优于1％，理论计算与实验结果一致。