神经网络-光度法同时测定食品中防腐剂和甜味剂

根据食品中常用防腐剂本甲酸和山梨酸及甜味剂糖精钠在紫外区均有吸收的特点，建立了一种以紫外分光光度法为基础对该三组分同时测定的方法，光谱数据采用作者自编的径向人工神经网络MATLAB程序进行处理，苯甲酸、山梨酸和糖精钠的平均标准偏差分别为1.60%、5.23%和1.21%，回收率大为95.0-102.0%之间，将该法应用于食品中二组分的测定，获得较为满意的结果。     

三峡工程用中热硅酸盐水泥品质指标控制的意义及方法

为确保用于大坝工程中水泥的质量, 1998年中国长江三峡工程开发总公司 (以下简称"总公司" )委托国家水泥质量监督检验中心对供应三峡大坝水泥的生产厂进行驻厂监督三峡工程用中热硅酸盐水泥 R2O和 MgO指标,并根据各厂的实际情况订出具体监控办法。笔者作为国家水泥质量监督检     

20%单氰乳剂剂型研究

本文所叙述的单氰乳剂，是一种新的复配农药制剂。它不仅增效作用显著，对为害农作物的蚜虫和红蜘蛛有很强的杀灭作用；而且其剂型独特，为国内尚不多见的水包油型的复配农药新制剂－微乳剂。该制剂生产工艺简单，产品性能稳定，常温贮存一年，有效成分分解率低于１．５％；在６０℃至－５℃范围内，其产品均为均相透明的液体，且乳化性能十分优良。目前该品种已取得农药登记，正式投产。     

Kinetics of the peracetic acid decomposition: Part II: pH effect and alkaline hydrolysis

The effect of pH on the decomposition of peracetic acid in an aqueous solution was studied. It was found that three potential reactions, namely i) the spontaneous decomposition, ii) the hydrolysis and iii) the transition metal catalysed decomposition, are responsible for the consumption of peracetic acid. The spontaneous decomposition reaches its maximum at pH 8.2, while both the hydrolysis and metal ion catalysed decomposition increase as the pH increases. At pH 10.5 and higher, the hydrolysis becomes dominant when the metal ion catalysed decomposition is minimized by the addition of DTMPA. The kinetics of the peracetic acid hydrolysis was developed, which can very well predict the development of peracetic acid and hydrogen peroxide during the decomposition reaction.     

Stresses of cohesionless granular flows in liquids

We construct constitutive relations for friction stress, slide stress and collision stress of cohesionless granular flows. We propose that the friction stress and slide stress could be neglected when τ_c/τ_e < 0.02, where τ_c represents the interval time experienced by a given particle between two consecutive binary collisions and τ_e the particle relaxation time. We applied these constitutive relations to a simulation of solid-liquid flow in an inclined chute and found the simulation results agree with experimental data.     

Preparations and properties of thermosensitive terpolymers of N‐isopropylacrylamide,sodium 2‐acrylamido‐2‐methyl‐propanesuphonate,and N‐tert‐butylacrylamide

Terpolymers based on N‐isopropylacrylamide, sodium 2‐acrylamido‐2‐methyl‐propanesulfonate, and N‐tert‐butylacrylamide were synthesized by free‐radical copolymerization with 2,2′‐azobisisobutyronitrile as an initiator. The lower critical solution temperatures (LCSTs) of the linear polymer aqueous solutions were determined by the measurement of the transmittance on UV at different temperatures. The influence of the polymer concentration, polymer composition, and ionic strength on the LCSTs of the linear polymers was investigated. The LCST decreased with increases in the hydrophobic monomer N‐tert‐butylacrylamide, polymer concentration, and ionic strength. The phase transition became sharp when the polymer concentration and ionic strength increased. Meanwhile, the crosslinked hydrogels were prepared with the same recipe used for the linear terpolymers, but a crosslinker was added to the reaction system. The swelling ratios of the hydrogels at various temperatures and salt solutions were determined. The hydrogels possessed both high swelling ratios and thermosensitivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

HS－900有机硅密封抗渗防水剂性能的研究

ＨＳ－９００有机硅密封抗渗防水剂是一种新型的有机硅改性硅酸盐防水材料。具有良好的抗渗性能和耐酸碱腐蚀能力。将其涂于低标号混凝土材料上，效果尤其明显。     

高温浓硫酸液下泵的故障分析及处理

安徽铜都铜业股份有限公司金昌冶炼厂新建 300 kt／a铜冶炼烟气制酸装置干燥塔入口烟气温度(30±2)℃,烟气ψ(SO_2)9％±1％。干燥塔循环槽采用2台单级单吸离心立式悬臂液下泵,型号为LSB780-30B,一开一备。吸收塔循环槽液下泵型号也为LSB780-30B,为2台泵并联。     

Kinetics of hydrogen peroxide bleaching of ALCELL® derived pulp

In this study, a kinetic model of the final bleaching stage with hydrogen peroxide in a totally chlorine free (TCF) bleaching sequence for ALCELL® processed pulp was developed. The model was based on the rate of chromophore destruction characterized by the decrease in the light absorption coefficient of bleached pulp at 457 nm, C_K. Based on the fact that the chromophore destruction proceeds rapidly in an initial phase followed by a much slower reaction during which a “floor-level” chromophore concentration is approached asymptotically, we propose that the hydrogen peroxide stage of the ALCELL® derived pulp in the studied TCF sequence consists of two distinct phases. The initial phase is a very fast reaction. The rate equation of the second phase was determined as: which is valid in a pH range of 10.5 to 11.5 and a temperature range of 60 to 92.5°C.     

Integrated size and topology optimization of skeletal structures with exact frequency constraints

The present paper studies the integrated size and topology optimization of skeletal structures under natural frequency constraints. It is found that, unlike the conventional compliance-oriented topology optimization problems, the considered problem may be strongly singular in the sense that the corresponding feasible domain may be disconnected and the global optimal solutions are often located at the tips of some separated low dimensional sub-domains when the cross-sectional areas of the structural components are used as design variables. As in the case of stress-constrained topology optimization, this unpleasant behavior may prevent the gradient-based numerical optimization algorithms from finding the true optimal topologies. To overcome the difficulties posed by the strongly singular optima, some particular forms of area/moment of inertia-density interpolation schemes, which can restore the connectedness of the feasible domain, are proposed. Based on the proposed optimization model, the probability of finding the strongly singular optimum with gradient-based algorithms can be increased. Numerical examples demonstrate the effectiveness of the proposed approach.