酸性离子液体催化花生壳制备还原糖条件的优化

论文以离子液体1-丁基-3-甲基咪唑氯([Bmim]Cl)为溶剂,酸性离子液体1-磺酸丁基-3-甲基咪唑硫氢酸盐([HSO3-(CH2)4-mim][HSO4])为催化剂,直接应用于花生壳进行水解反应制备还原糖,采用二硝基水杨酸法(DNS)测得体系中还原糖的含量。在单因素实验基础上,选择催化剂用量、反应温度、反应时间为自变量,还原糖产率为响应面值,利用Box-Behnken中心组合试验和响应面分析法,建立二次回归模型,得到最佳水解工艺条件:反应温度123℃,反应时间39 min,催化剂用量10%。在此优化条件下,还原糖产率达到70.38%。并且该离子液体反应体系重复使用5次后仍保持较高的催化活性。     

常压下Ag-TiO2纳米管制备及光催化反应动力学研究

首次在常压下,以试剂TiO2、NaOH和AgNO3为原料,碱熔温度为700℃,水热法制备了Ag-TiO2复合纳米管光催化剂。TEM和XRD用于纳米管组织与形貌表征。研究了纳米管制备以及用于模拟污染物甲基橙(MO)光催化降解的实验条件。结果表明,原料是否碱熔,水热温度高低和时间长短,对光催化剂性能影响明显;当MO溶液初始浓度Co为4mg/L、光催化降解反应持续4h,光催化降解率达到99%。降解反应的速率常数k与Co呈0.9966级的动力学关系。     

基于实验设计建模优化纳米复合光催化剂ZnO/SnO2的制备条件

采用序贯实验思路,首先基于Plackett-Buman(PB)设计实验数据,经主效应分析和逐步回归筛选出影响制备ZnO/SnO2 粉体性能的主要因素;再以筛选出的Zn/Sn摩尔比及反应时间2个因素设计U12(4×3)均匀设计实验,用PSO-2次回归方法基于该实验数据建立制备ZnO/SnO2粉体光催化降解甲基橙脱色率DC的预测模型,通过非线性规划求模型最优解获得优化的ZnO/SnO2制备条件.将在优化条件下制备获得的ZnO/SnO2粉体用于光催化降解甲基橙,降解30min的DC实验平均值为96.17,模型预测值则为DC=95.66,DC实验值与预测值相对误差仅为0.53%,表明模型可靠.对该粉体采用XRD和SEM进行形貌、粒径及组成分析,表征结果显示该粉体大致呈球形、粒径主要分布在(20～30)nm,粉体中有少量Zn2SnO4产生.     

响应面优化—超声辅助提取丹参多糖工艺

响应面优化超声波法提取丹参多糖工艺;方法:在单因素试验的基础上,采用三因素三水平响应面分析法,利用软件Design Expert试验设计原理得到二次线性回归方程,以多糖产率为响应面值作响应面图;结果:确定超声提取丹参多糖最佳工艺条件为:超声功率90 W、超声温度50℃、提取时间30 min、液固比为55:1,提取次数为2次,丹参多糖产率为8.23%。统计结果表明,模型相关系数R~2=0.8398。变异系数C.V值较低,说明实验有较好的稳定性;超声功率的二次项和液料比的二次项均达到极显著水平(P0.01)。验证实验表明,所得模型方程能较好地预测实验结果,拟合度较好。结论:超声提取法与传统水煮法相比,不仅能耗低、产率高,且提取时间缩短16倍。     

环己烷/正丁醇/Tween80/水体系中纳米二氧化钛的合成及其可见光下光催化降解甲基橙性能的研究

本研究以浓硫酸作抑制剂,以钛酸四丁酯为钛源,在环己烷/Tween80/正丁醇/水微乳液体系中成功制备出粒径小、分散性高的纳米二氧化钛(TiO_2)。采用XRD、SEM和TEM等手段对所制备的材料进行表征,结果表明:所制备的TiO_2均为单一的锐钛矿型纳米TiO_2颗粒,且形状为规则的球形、尺寸分布均匀,团聚度小,颗粒粒径为14 nm左右。光催化性能的研究结果表明所制备的TiO_2在可见光下6 h之内对甲基橙的降解效率可达到94%。对光催化机理进行了探讨,初步证明了在TiO_2光催化降解甲基橙的体系中,起主要作用的是光生电子的还原作用。     

试验设计优化Mn掺杂ZnO纳米催化剂的制备

按2⁵部分因子试验设计安排实验,以光催化降解甲基橙（MO）溶液脱色率DC（%）为目标值,考察掺锰量V_MnNO3、熟化温度T₁、熟化时间t₁、煅烧温度T₂和煅烧时间t₂对制备的Mn掺杂纳米ZnO光催化性能的影响,经分析确定影响产品光催化性能的主要因素为V_MnNO3、T₁和T₂。以此3因素按3²全因子试验设计进行实验并分析试验结果,获得Mn掺杂纳米ZnO光催化剂的优化制备条件为V_MnNO3=0.5mL、T₁=70℃、t₁=15min、T₂=600℃和t₂=2.5h。0.05g优化制备产品在紫外光照射下光催化降解100mL10mg/L的MO溶液30min的DC实验平均值为95.58,与Minitab软件对产品的优化预测值95.75的相对误差仅为-0.18%;在可见光下降解MO溶液120min的DC实验平均值为65.11。XRD和SEM对优化产品的表征表明,其主要由粒径分布在（20～30）nm的不规则的颗粒状纳米ZnO组成。由紫外-可见分光光度计测定并计算得出优化产品的带隙能E_g约为3.25eV,较同等条件下制得的纳米ZnO带隙能E_g（3.36eV）低0.11eV。     

基于SAS9.1的芽孢杆菌发酵条件优化

为了提高菌株Bacillus sp.ULi-11生物合成(R)-α-羟基苯乙酸的产率,本文采用响应面法对其发酵条件进行优化。首先采用Plackett-Burman试验设计对影响产率的7个初始发酵条件进行评价,筛选出3个主要因素:温度、装液量和接种量。再用最陡爬坡方法逼近最大响应区域后,用Box-Behnken试验设计及响应面分析法进行回归分析,确定出最佳发酵条件分别为:温度35℃、装液量21.6 mL、接种量0.55%、种龄16 h、pH 7.2、底物加入时间19 h、转速200 r/min。在此条件下,进行3批次的摇瓶实验,得到的(R)-α-羟基苯乙酸产率达81.71%,比优化前提高了12.7%。结果表明采用响应面试验设计优化方法有效提高了(R)-α-羟基苯乙酸的产率,为(R)-α-羟基苯乙酸的工业化应用提供了依据。     

负载亚甲基蓝的纳米磁性碳粉修饰电极研制及DNA的测定

采用化学沉积法在碳粉上负载纳米Fe3O4颗粒,吸附亚甲基蓝后吸着在固体石蜡碳糊电极上,制成了亚甲基蓝修饰的磁性电极.研究了在0.1 mol/L的NH4Cl溶液中,DNA对电极上修饰物亚甲基蓝的电氧化还原作用,考察了多种实验条件对峰电流的影响.在-0.6～0.3 V电压下,在0～12 mg/L范围内DNA浓度与Δia成反比,从而实现对DNA的测定.研究了亚甲基蓝修饰的磁性电极的电化学行为.该磁性修饰电极集分离、富集和测定于一身,且所得的修饰电极具有灵敏度高、稳定性好、表面易更新等优点.     

拟因素法正交试验设计优化纳米ZnO-SnO_2的制备

以沉淀反应时间(A)、Zn/Sn反应剂量摩尔比(B)、沉淀剂与总金属离子溶液(ZnSO_4溶液和SnCl_4溶液)的体积比(C)、熟化时间(D)、煅烧时间(E)、煅烧温度(F)6个因素作为影响制备复合催化剂ZnO-SnO_2的主要因素,采用拟因素法正交试验设计按正交试验设计表L_(16)(2~(15))安排纳米ZnO-SnO_2的制备实验。获得纳米ZnO-SnO_2复合催化剂的优化制备条件为:A=8min、B=85:15、C=2:1、D=6 min、E=1h、F=700℃。将优化制备产品用于光催化降解10mg/L的甲基橙溶液30 min,3次实验结果溶液脱色率DC平均值为99.05%,与按效应计算的估计值97.78%的相对误差仅为1.27%。通过XRD谱图分析优化制备产品的组成和粒径,确定该复合催化剂的主要成分是ZnO和SnO_2,另有少量的Zn_2SnO_4;粒径主要分布在15-35纳米之间。根据紫外-可见分光光度计的测定结果,计算获得优化制备产品的带隙能(Eg)为3.30 eV,比纳米ZnO的带隙能低0.07 eV。     

基于支持向量机的TiO_2/C复合气凝胶光催化性能预报

TiO_2/C复合气凝胶光催化性能与材料的组成、孔结构参数密切相关,本文利用支持向量机的方法建立材料原始合成配方与TiO_2/C复合气凝胶光催化性能之间的定量预报模型。SVR建模和留一法交叉验证所得材料降解率计算值与实验值之间的相关系数平方(R~2)分别为0.929和0.884。利用该模型预报了2个新的实验样本,其降解率预报结果和实验结果非常接近,相对误差小于4%。     

Performance of a-WO3/LiClO4-PC electrochromic displays

This paper deals with the improvements in response time and reliability of the aWO₃/LiClO₄-PC (propylene carbonate) electrochromic display. Response time was improved by adopting the highly porous a-WO₃ film, the porous reflector and the high surface area non-polarizable counter-electrode. Results from the reliability tests indicated that the ECD had a sufficient lifetime for practical applications such as in watches, clocks and calculators. The mechanism of performance drift upon cycling the display is investigated using ESCA, AES and atomic absorption methods.     

Bayesian inference for an item response model for modeling test anxiety

We develop a Bayesian binary Item Response Model (IRM), which we denote as Test Anxiety Model (TAM), for estimating the proficiency scores when individuals might experience test anxiety. We consider order restricted item parameters conditionally to the examinees’ reported emotional state at the testing session. We consider three test anxiety levels: calm, anxious and very anxious. Using simulated data we show that taking into account test anxiety levels in an IRM help us to obtain fair proficiency estimates as opposed to the ones obtained with three two-parameter logistic IRM (3PM) by Birnbaum (1957, 1968). For the 3PM, the proficiency estimates tend to be positively biased for both, calm and anxious examinees.     

基于ZnO/Glass声表面波器件的高速紫外传感特性研究

基于氧化锌/玻璃(ZnO/Glass)结构的声表面波(SAW)器件可以用来制作性能优良的紫外探测器。使用有限元分析软件COMSOL Multiphysics仿真了该种结构的声表面波器件,并得到其S11参数。基于仿真结果,制备了相应的SAW器件,实验所用ZnO薄膜采用直流反应磁控溅射方法沉积,所制备的ZnO薄膜呈(0002)取向。基于该种结构的SAW紫外探测器对紫外光的反应时间仅3 s,其紫外探测的灵敏度高达36.4×10-6/mW/cm2。     

二维连续体结构形状优化及其在MSC Nastran上的二次开发

将响应面方法引入到二维连续体结构形状优化中,结合有限元方法,通过一系列的结构分析,近似拟合出状态约束(应力和位移)对设计变量的显函数,代替复杂的解析灵敏度分析,以MSC Patran为平台采用PCL语言开发二维连续体形状优化的程序. 文中算例通过与差分法的比较表明这一方法的有效性和可靠性.     

Multi-objective robust design of helical milling hole quality on AISI H13 hardened steel by normalized normal constraint coupled with robust parameter design

Helical milling is a hole-making process which has been applied in hardened materials. Due to the difficulties on achieving high-quality boreholes in these materials, the influence of noise factors, and multi-quality performance outcomes, this work aims the multi-objective robust design of hole quality on AISI H13 hardened steel. Experiments were carried out through a central composite design considering process and noise factors. The process factors were the axial and tangential feed per tooth of the helix, and the cutting velocity. The noise factors considered were the tool overhang length, the material hardness and the borehole height of measurement. Response models were obtained through response surface methodology for roughness and roundness outcomes. The models presented good explanation of data variability and good prediction capability. Mean and variance models were derived through robust parameter design for all responses. Similarity analysis through cluster analysis was performed, and average surface roughness and total roundness were selected to multi-objective optimization. Mean square error optimization was performed to achieve bias and variance minimization. Multi-objective optimization through normalized normal constraint was performed to achieve a robust Pareto set for the hole quality outcomes. The normalized normal constraint optimization results outperformed the results of other methods in terms of evenness of the Pareto solutions and number of Pareto optimal solutions. The most compromise solution was selected considering the lowest Euclidian distance to the utopia point in the normalized space. Individual and moving range control charts were used to confirm the robustness achievement with regard to noise factors in the most compromise Pareto optimal solution. The methodology applied for robust modelling and optimization of helical milling of AISI H13 hardened steel was confirmed and may be applied to other manufacturing processes.     

New formulation of minimum-bias central composite experimental design and Gauss quadrature

Response surface methods provide a powerful tool for constructing approximations to complex response functions. Statistical design of experiments is usually used to select optimal points that minimize the error in the resulting response surface approximation. Traditionally, data points are selected using minimum-variance designs, for example the D-optimal design, which may result in large bias errors for low-order approximation. Minimum-bias criteria have been developed for selecting data points to minimize the bias error of a response surface approximation. The present work developed a minimum-bias counterpart to the popular minimum-variance central composite designs. In addition, a new formulation of the minimum-bias design that assigns unequal weights to the design points, based on Gauss quadrature, is explored. Example problems are evaluated and the results obtained from D-optimal, the traditional minimum-bias, and the new Gauss-quadrature-based minimum-bias designs are compared. It is shown that the Gauss-quadrature-based minimum-bias design criterion results in the most accurate approximations and provides analytical solutions to a wider range of approximation domains than the traditional minimum-bias design. Response surface approximations based on minimum-bias central composite designs are more accurate than those constructed from traditional central composite design. Moreover, it is shown that using weights in regression has little influence on the accuracy of the response surface approximation in Gauss-quadrature minimum-bias designs.     

The ability of information systems development project teams to respond to business and technology changes: a study of flexibility measures

The socio-technical perspective suggests that information systems development projects (ISDPs) involve both organizational and technical dimensions. As both the organizational and technical aspects of ISDPs frequently change, the ISDP team's flexibility in responding to these changes has become a critical success factor for system development. While the importance of ISDP team flexibility has increased, the research literature lacks a consistent definition and validated measures of the construct. Drawing upon the socio-technical and the capability-based perspectives and using a systematic multi-stage approach, we identified major business and technology changes and developed measurement scales of ISDP team flexibility along two dimensions: Response Extensiveness and Response Efficiency. The results of a confirmatory factor analysis using survey data from 505 ISDP managers suggested that the final measurement scales exhibited adequate levels of measurement properties including unidimensionality, reliability, discriminant validity, factorial invariance and nomological validity. In addition, our results revealed an interesting negative relationship between Response Extensiveness and Response Efficiency, indicating a trade-off between the two dimensions of flexibility. Our result indicated that while the ISDP teams experienced and responded more extensively to business changes than technology changes, they were much less efficient in dealing with business changes than technology changes.     

Comparison and classification of 3D objects surface point clouds on the example of feet

One of the main tasks of shoe manufacturing is the production of well fitting shoes for different specialized markets. The key to conduct this properly is the analysis of the factors that influence the variations of the foot shape. In this paper methods and results of clustering and analysis of 3D foot surfaces are presented. The data were collected from a study with more than 12,000 feet that have been laser-scanned. The database contains point clouds acquired from persons coming from different regions of the world. Furthermore, additional personal data were collected. Two different methods for quantifying the similarity of 3D surface point clouds are therefore developed. The first method generally works on nearly arbitrary 3D surface point clouds, while the second one is specialized on foot data sets. These similarity measures were used on the data sets of the foot-shape study, together with clustering and feature quality evaluation methods. The purpose was to obtain information about the impact of, and the relationship among, the different factors influencing the shape of a foot. Through the observations of the experiments presented here it was possible to build up a hierarchy of different levels of feature-groups determined by their impact on the foot shape. Furthermore, an investigation of the quality and amount of impact of the features, according to their ability to separate specific subgroups of persons, is shown. Based on these results it was possible to select those features, which result in the largest effect when designing shoes for e.g. the Asian versus European markets.     

Computer response time measurements of mood,fatigue and symptom scale items: Implications for scale response time uses

Response time (RT) to computer-administered questionnaire items were measured in two studies to evaluate how useful it might be in various research areas. These studies had different start-of-day times and each had two exercise levels. Thirty subjects were tested over two continuous 20 hour days (CW1 and CW2) with three hours of nap time allowed between days. The scales analyzed were the Vigor and Fatigue scales of the Profile of Mood States (POMS), a symptom checklist, a Guttman type fatigue scale, and a Negative and Positive mood scale. Response time to most scales were faster on CW2, whereas the symptom, negative mood and fatigue scales increased and the vigor and positive scale values were lower CW2. There were no differences between exercise levels or start time studies in scale RT. Reaction time on a simple psychomotor task was significantly slower on CW2, but was not correlated with any scale RT either day, indicating that response speed was not involved in scale RT. Also, there were no significant correlations between reading speed or reading grade level with scale RTs. Mean POMS Fatigue scale RT was highly correlated with the mean scale value both days, showing slower RT with higher fatigue scale values. The Positive Scale took longer than the Negative Scale, and the POMS Vigor took longer than Fatigue both days showing some support for the theory that moods congruent with the present state are more prominent in memory as indicated by faster FT. The most complex scale (Guttman) had the longest RT while the most simple (dichotomous) had the shortest RT. Scale RT showed some usefulness as a measure in a variety of research areas.     

Exploring undergraduates' perspectives and flipped learning readiness in their flipped classrooms

This study surveyed 84 undergraduate students, majoring in education, in order to gather their perspectives regarding flipped classrooms and investigate their readiness levels for flipped learning. After the implementation of flipped learning for an entire semester, surveys were distributed in two flipped classrooms that were taught by the same instructor. Students showed particular preferences for the “Bring Your Own Device” and the Instant Response System features of the flipped classroom. Approximately 60% agreed with the idea of flipped classrooms, but only 39% agreed that the flipped classrooms met their learning needs. Their readiness levels for flipped learning were moderately above the average levels, and males or juniors (compared with freshmen), felt more prepared for flipped learning. In general, course grades, self-directed learning readiness, and group work preference can predict the different readiness dimensions. The findings may enhance educators' understanding in how to apply the flipped learning model in ways that are most beneficial for their own students.