用均匀设计优化分散聚合法制备P(St/nBA)微球体

用均匀设计法设计苯乙烯和丙烯酸正丁酯的分散共聚合反应的试验,用DPS数据处理软件进行线性和二次逐步回归分析,建立聚合物粒子转化率、粒径及粒径分布这3个指标和各因素(单体总量及不同单体配比、稳定剂用量、引发剂用量、反应介质极性和温度)之间的回归方程,比较线性回归与二次回归的拟合度,考察各因素对3个指标影响的大小;然后用MATLAB软件优化二次回归方程,得到在约束条件下的最优配方和预测值,并进行实验验证。结果表明:二次回归方程的相关系数R=0.999997,明显优于线性回归的结果R=0.795144;各因素对3个指标的影响存在着交互作用,对各指标影响最显著的单因素及影响顺序如下:对转化率为引发剂用量>分散介质极性,对粒径大小为稳定剂用量>温度>单体中丙烯酸丁酯浓度>初始单体总质量;对粒径分布为分散介质极性>稳定剂浓度>温度;在最优配方下用二次回归方程得到的预测值与实验值之间各指标的误差分别为:转化率|△K|<0.6%,平均粒径|△(?)|<6%,粒子分散系数|△ε|<30%。     

玻璃体系对铜浆性能的影响

本文采用熔融-水淬法制备了SiO2-B2O3-Bi2O3、SiO2-B2O3-ZnO和SiO2-B2O3-CaO 3种体系的无铅玻璃粉,根据玻璃粉的XRD和差热分析结果,分析并讨论了玻璃析晶、成玻化程度及玻璃转化温度Tg对铜浆性能的影响,并通过SEM观察了铜膜的表面形貌,验证了以上分析。结果表明:SiO2-B2O3-CaO体系的无铅玻璃粉具有良好的成玻性和合适的玻璃转化温度,采用该体系作为铜浆的玻璃相,铜浆性能较好。     

同心圆柱环型电容式肥液浓度传感器设计与试验

设计了一种同心圆柱环型电容式肥液浓度传感器,主要由稳压器、10MHz有源晶振、施密特触发器、电容传感器和真有效值检测器组成,检测结果以直流电压形式输出.在8×10 -1~1×10 -3mol/L浓度范围内,配置一系列待测肥液对传感器进行了试验:1)标定试验结果表明传感器输出电压与浓度对数呈线性负相关,决定系数R2>0.987;2)温度变异性试验结果表明传感器输出电压与肥液温度呈线性正相关,其决定系数R2=0.98417;3)稳定性试验结果表明同一浓度下连续测量10 h内测量最大差值为0.0003 mol/L,传感器稳定性良好;4)验证试验结果表明最大检测误差为9.8%.满足在线检测的实际应用要求.     

废次烟叶中茄尼醇的提取工艺研究

本实验以废次烟叶为原料对茄尼醇的提取工艺进行了研究。以茄尼醇的得率为考察目标,在单因素试验基础上,通过五因素、五水平2次旋转正交组合试验设计,研究了原料粒度,粒液比,pH值,提取温度,提取时间五因素对茄尼醇提取的影响。结果表明pH值和料液比对茄尼醇得率有极显著影响,原料粒度和提取时间对茄尼醇得率有显著影响,其他因素对茄尼醇得率无显著影响。得到茄尼醇的最佳提取工艺为:原料粒度60目,料液比1:20,pH11,提取温度50℃,提取时间1.5 h,茄尼醇提取率和含量分别达3.69%和26.5%。该工艺提取茄尼醇效果好,提取率和含量均高于传统提取法,工艺重复性和稳定性好,适合于工业化生产。     

LSCO厚膜电阻浆料的制备与电性能研究

采用传统固相合成法制成的LSCO作为功能相,并用钙硼硅玻璃作为无机粘结相制备了厚膜电阻浆料。研究了玻璃相的含量、峰值烧结温度对厚膜方阻及电阻温度系数的影响。结果表明:当浆料固相成分中玻璃相的质量分数为3%～9%(体积分数为11.11%～28.56%)时,制备的厚膜电阻浆料方阻变化范围为1kΩ/□～10MkΩ/□。电阻温度系数为-8000×10-6/℃～-5000×10-6/℃。     

溶胶-凝胶膜修饰碘电极测定食物中Vc含量

用溶胶-凝胶包埋硝酸银制备了碘电极,并研究了其性能、测定条件及干扰物质的影响。提出了用碘电极指示Vc与I2定量反应释放的I-的浓度来测定Vc含量的方法。该电极在0.1mol/LKNO3,pH=2.0～6.0溶液中,对Vc浓度在10-1～10-5mol/L范围内呈Nernst响应,响应斜率为59.8mV/pVc,检测下限为7.9×10-6mol/L,回收率为95.4%～103.1%,可广泛用于医药、食品等行业对Vc含量的测定。     

固态pH 探测电极的制备及其性能表征

我们采用熔融碳酸锂(LiCO3)氧化法制备了固态Ir／IrO2 pH电极，同时制备了改进型固态Ag／AgCl参比电极，并对它们的性能进行了表征。实验结果显示，在pH=0-14的溶液中，Ir／IrO2电极与参比电极电位差与pH值呈现良好的线性关系，直线斜率为-62．429mV／pH，截距为607．97mV，相关系数R2=0．993。温度对新型pH传感器响应信号的影响符合Nernst方程，易于进行温度校正。盐度对电信号强度的影响是线性的，在介质盐度已知，或向步测定介质盐度的前提下，可从响应电信号强度及盐度确定待测介质的pH值。     

木霉T21和T22原生质体制备和再生研究初报

采用不同菌龄、酶液配比、缓冲液-稳定剂系统、酶解时间等条件对木霉T21、T22原生质体制备和再生影响的试验表明,木霉T21和T22原生质体制备和再生的最适条件为:以纤维素酶:蜗牛酶:溶菌酶=5.0:2.5:2.5(g·L-1)的酶液配比,0.2mol·L-1磷酸缓冲液(phosphatebuffersolution,PBS),pH值5.8和0.6mol·L-1蔗糖组成的缓冲液稳定剂系统,将培养了20h的菌丝体在30℃下,酶解3h,最后获得原生质体数量平均约为2.7×1010个·L-1。     

基于SEBS/纳米炭黑复合膜的电阻式应变传感材料制备及其性能研究

以热塑性弹性体苯乙烯/乙烯/丁烯-苯乙烯(SEBS)和炭黑纳米颗粒为原料,采用熔融共混-模压成型法制备了SEBS/纳米炭黑复合电阻式应变传感膜.实验中,研究了该薄膜的力学性能及其电阻应变的传感性能.力学测试表明,该复合应变传感膜具有优异的弹性力学特性,断裂伸长率达410.8%,断裂强度达2.5 MPa,经1000次循环拉伸后,其形变率仅为3.0%.应变传感测试显示,随着复合膜拉伸倍率增大其电阻变化呈线性提高,并且动态拉伸电阻变化速率高于静态条件下的电阻变化速率.该复合应变传感膜应用于人体胳膊弯曲试验显示,可较为精准的记录胳膊弯曲量和弯曲次数,进而得知人体的运动活动量,在健身和康复等领域有重要的潜在应用价值.     

环糊精-卟啉与二苯乙烯衍生物包结作用的分子动力学模拟研究

为了考察环糊精-卟啉与二苯乙烯所形成包结物的稳定性对环糊精-卟啉催化二苯乙烯环氧化选择性的影响,本文采用分子动力学方法研究了环糊精-卟啉与一系列二苯乙烯衍牛物所形成的包结物,并从主客体之间的相互作用能、相对距离的变化及包结结构3个方面考察了包结物的稳定性.计算结果表明,不同的二苯乙烯衍生物与环糊精-卟啉所形成包结物的稳定性不同,二苯乙烯两端的取代基与卟啉两端环糊精空腔的几何尺寸越匹配,环糊精-卟啉与二苯乙烯衍生物所形成包结物的结合稳定性越强,越有利于环糊精-卟啉对二苯乙烯进行选择性催化环氧化.     

Optical fiber sensing element based on luminescence quenching of silica nanowires modified with cryptophane-A for the detection of methane

An optical fiber sensing element based on luminescence quenching of cryptophane-A/silica nanowires was successfully constructed and used to dynamically monitor methane gas at low concentration below 3.5% (v/v). The optical fiber device was designed to operate via luminescence reflection. The sensing properties of optical sensing element to methane at room temperature were characterized. The sensing element shows an intensive and stable blue luminescence when excited by UV light source at wavelength of 380 nm, and it is efficiently quenched by molecular methane. The response of the sensing element demonstrates excellent linear Stern-Volmer behavior at the fixed wavelength 439 nm within the methane concentration range between 0.1% and 3.5% (v/v). A detection limit of below 0.1% (v/v) is estimated for the methane sensing element. This newly developed methane sensing element has significant advantages over the currently available methane sensors such as fast response and recovery (within seconds), good repeatability, selectivity, and long-term stability.     

Is information systems a discipline? Foucauldian and Toulminian insights

Following the Kleinian spirit, this study takes a critical view of the existing orthodoxy within information systems (IS) and reframes the ongoing discussion concerning the intellectual core, identity and disciplinary status of IS using the disciplinary analysis of Michel Foucault and Stephen Toulmin. Instead of limiting the discussion to specific paradigms, topics, subjects or content, it focuses on the characteristics, rules and goals of IS as an academic field. A disciplinary lens is used to frame what it means to be a field, discipline and science, and in the process the study uncovers four doxas that have shaped the development of the IS field: (1) the IS research community sees no difference between fields, disciplines or sciences; (2) IT changes so rapidly, and thus the IS field needs to change to remain relevant; (3) disciplines are by definition rigid, inflexible and uni-theoretical and (4) because IS is pluralistic, IS should not become a discipline. This study's analyses of the IS field's discursive formation and intellectual ideals offer novel perspectives that allow for the integration of the IS field's plurality and diversity. To transform the IS field from its multimodal existence into a vibrant, diverse, academically and socially relevant and influential discipline, the study proposes actionable strategies that include (1) agreeing on the intellectual ideals for IS, (2) focusing on conceptual formation, (3) focusing on theory construction, (4) erecting genealogical boundaries and (5) fostering the development of professional bodies.     

An automated framework for software test oracle

Context

One of the important issues of software testing is to provide an automated test oracle. Test oracles are reliable sources of how the software under test must operate. In particular, they are used to evaluate the actual results that produced by the software. However, in order to generate an automated test oracle, oracle challenges need to be addressed. These challenges are output-domain generation, input domain to output domain mapping, and a comparator to decide on the accuracy of the actual outputs.

Objective

This paper proposes an automated test oracle framework to address all of these challenges.

Method

I/O Relationship Analysis is used to generate the output domain automatically and Multi-Networks Oracles based on artificial neural networks are introduced to handle the second challenge. The last challenge is addressed using an automated comparator that adjusts the oracle precision by defining the comparison tolerance. The proposed approach was evaluated using an industry strength case study, which was injected with some faults. The quality of the proposed oracle was measured by assessing its accuracy, precision, misclassification error and practicality. Mutation testing was considered to provide the evaluation framework by implementing two different versions of the case study: a Golden Version and a Mutated Version. Furthermore, a comparative study between the existing automated oracles and the proposed one is provided based on which challenges they can automate.

Results

Results indicate that the proposed approach automated the oracle generation process 97% in this experiment. Accuracy of the proposed oracle was up to 98.26%, and the oracle detected up to 97.7% of the injected faults.

Conclusion

Consequently, the results of the study highlight the practicality of the proposed oracle in addition to the automation it offers.     

Input/Output Decoupling of Square Linear Systems by Dynamic Two‐Parameter Stabilizing Control

Analytical expressions of the free parameters of a two‐parameter stabilizing control (TPSC), solving an input/output (I/O) decoupling problem, are presented, and stability conditions are given. Multi‐input‐multi‐output (MIMO), proper, lumped and linear time invariant (LTI) systems are considered. These systems have stabilizable and detectable realizations. The separation principle is applied to design a dynamic output control in a controller‐observer feedback configuration. The I/O relation of the overall system is equivalent to a subsystem, in which the I/O decoupling problem has a solution. Also, if the state dimension of the plant is even, and is double the input dimension of the plant, then coprime factorizations of the plant used for the stabilizing controllers are proposed. The results are illustrated through an example.     

Lie- and chronologico-algebraic tools for studying stability of time-varying systems

We will study stability and asymptotic stability for time-varying systems described by ODEs of the form , where f(t,x) is 1-periodic with respect to t and >0 is a small parameter. Since the discovery of stabilizing effect of vibration in the reverse pendulum example, there have been a lot of study regarding stability of such systems and design of fast-oscillating stabilizing feedback laws. In this paper we suggest an approach which is kind of high-order averaging procedure based on Lie algebraic formalism and the formalism of chronological calculus. This latter is a method of asymptotic analysis for flows generated by time-variant ODE. We apply the approach to study stability issues for linear and nonlinear systems. In particular, we derive conditions of stability for the second- and third-order linear differential equations with periodic fast-oscillating coefficients, we study output-feedback stabilization of bilinear systems and consider high-order averaging procedure for nonlinear systems under homogeneity assumptions. At the end we study the problem of stabilization of nonholonomic (control-linear) systems by means of time-varying feedbacks.     

From Youla–Kucera to Identification, Adaptive and Nonlinear Control

Some 20 years ago, formulae were presented for the set of all linear time-invariant controllers stabilizing a linear time-invariant plant. This paper traces the development of many ideas from these formulae, covering linear and control, identification, adaptive control and nonlinear systems.     

基于金属—有机骨架材料的C反应蛋白传感器研制

在常温下合成了Au纳米颗粒负载的超纳米结构金属有机骨架化合物(Au NPs/SNHKUST—1),并以其为标记材料标记C反应蛋白抗体.同时合成了中空状石墨烯纳米材料和Au纳米颗粒作为固定基质,制备了夹心型的C反应蛋白免疫传感器.通过检测标记物对H2 O2还原反应的催化电流,实现了对C反应蛋白的定量测定.传感器在C反应蛋白浓度为0.2~200 ng/mL的范围内线性良好的,线性相关系数R2=0.9947,检测下限为0.05 ng/mL,为C反应蛋白测定提供了一种新的简单快速的检测方法.     

A time-delay control algorithm for an industrial electric heater

This paper discusses stabilizing control for discrete systems with a time delay in the state variables. The control algorithms are based on the Lyapunov stability theory. For an industrial electric heater, a time-delay discrete model is identified using a recursive least squares technique, and real-time control via the proposed control algorithm to the heater is performed. The performance of the industrial application shows that the temperature variation in the heater is within ± 1.5°C (0.5%), and the system has good load change rejection and shorter recovery time.     

Effects of wall temperature on boundary layer stability over a blunt cone at Mach 7.99

Effects of wall temperature on stabilities of hypersonic boundary layer over a 7° half-cone-angle blunt cone are studied by using both direct numerical simulation (DNS) and linear stability theory (LST) analysis. Four isothermal wall cases with , as well as an adiabatic wall case are considered. Results of both DNS and LST indicate that wall temperature has significant effects on the growth of disturbance waves. Cooling the surface accelerates unstable Mack II mode waves and decelerates the first mode (Tollmien-Schlichting mode) waves. LST results show that growth rate of the most unstable Mack II mode waves for the cases of cold wall are about 45% and 25% larger than that for the adiabatic wall, respectively. Numerical results show that surface cooling modifies the profiles of and temperature in the boundary layers, and thus changes the stability characteristic of the boundary layers, and then effects on the growth of unstable waves. The results of DNS indicate that the disturbances with the frequency range from about 119.4 to 179.1 kHz, including the most unstable Mack modes, produce strong mode competition in the downstream region from about 11 to 100 nose radii. And adiabatic wall enhances the amplitudes of disturbance according to the results of DNS, although the LST indicates that the growth rate of the disturbance of cold wall is larger. That because the growth of the disturbance does not only depend on the development of the second unstable mode.     

Synthesis of robust discrete systems based on comparison with stochastic model

The problem of synthesis of the stabilizing control for a discrete linear system with uncertain parameters is considered. The stochastic model of comparison with parametric noise is constructed; the mean-square stability of this model implies the stability of the system with uncertain parameters varying in a given domain. For the case of the state feedback, the methods of synthesis of the robust stabilizing control based on the solution of either linear matrix inequalities or an auxiliary optimization problem with constraints in the form of linear matrix inequalities are proposed. The converging iterative algorithm of synthesis of the robust stabilizing control for the case of the output feedback is proposed. An example is given.