Overall control strategy of a coupled reactor/columns process for the production of ethyl acrylate

Ethyl acrylate (EA) is widely used in industry as a precursor for varnishes, adhesive, and finishes of papers and textiles. This important ester can be produced directly from ethanol (EtOH) and acrylic acid (AA) via esterification reaction with the presence of sulphuric acid as homogeneous catalyst. The proposed design flowsheet of this process includes a CSTR reactor coupled with a rectifier and an overhead decanter. In order to further purify the final EA product, another stripper is needed with its top vapor recycled back to decanter. The simplest and industrial easily applicable overall control strategy will be investigated with only one tray temperature control loop in each of the two columns. The final proposed overall control strategy of this process is found to be different than another similar coupled reactor/columns process published earlier [I-L. Chien, Y.P. Teng, H.P. Huang, Y.T. Tang, Design and control of an ethyl acetate process: coupled reactor/column configuration, J. Proc. Cont. 15 (2005) 435–449]. Both EtOH and AA feed flow rates are used as manipulated variables in the overall control strategy with CSTR heat duty left as throughput manipulator for the overall process. The final EA product with stringent specifications of 0.1 wt% EtOH and 0.005 wt% AA impurities can be achieved with this proposed overall control strategy despite feed flow rate and feed composition disturbances.     

Enhancement of condominium management based on the effect of quality attributes on satisfaction improvement

Condominium management (CM) businesses rely on continuous improvements to service quality (SQ) to increase consumer satisfaction (CS) and thereby improve operations. Lacking knowledge of SQ and CS results in poor efficiency. To develop cost-effective strategies for improvements, the relationship between SQ and CS must be investigated. This work proposes novel procedures to explore the relationship between identified SQ attributes and CS in the CM business. First, we conduct exploratory factor analysis to cluster intrinsically similar attributes into three constructs and identify significant attributes for subsequent assessment. Furthermore, resident satisfaction scores (RSSs) are computed to assess the relative importance rate (RIR) of investigated attributes by applying an adapted multivariate method to regress the RSSs on the performance of SQ attributes. To facilitate the decision-making process, the service-quality model evolved from the integration of an improved Kano’s approach and importance-performance analysis (IPA) is utilized to develop a prioritized strategy for satisfaction improvements in the CM business.     

基于加权朴素贝叶斯算法的调度指挥态势感知模块设计

针对调度与现场频繁电话沟通调度操作进程信息,以及无法提供给现货市场较精确的设备停复电时间作为边界条件的问题,将大数据挖掘理念引入了调度指挥领域,在南方电网调度指挥控制系统（Power Dispatch Command Control System,DCCS）的基础上,设计了一种对调度指挥态势进行实时感知的功能模块。该模块可通过DCCS获取调度员在业务准备关键节点的业务环境特征数据,采用加权朴素贝叶斯算法对调度员的实时忙碌程度进行挖掘,结合历史数据对忙碌系数进行匹配,并动态更新预计开展时间,得到结果后可传输至现货系统,作为节点电价计算的边界条件。此外,该模块还具备操作预约、操作通知、智能编排、态势展示等功能。模块上线后,减少了调度与现场有关操作信息的无谓沟通,所构建的数据模型也取得了较好的预测准确率。     

Real-time concurrency control in a multiprocessor environment

Although many high-performance computer systems are now multiprocessor-based, little work has been done in real-time concurrency control of transaction executions in a multiprocessor environment. Real-time concurrency control protocols designed for uniprocessor or distributed environments may not fit the needs of multiprocessor-based real-time database systems because of a lower concurrency degree of transaction executions and a larger number of priority inversions. This paper proposes the concept of a priority cap to bound the maximum number of priority inversions in multiprocessor-based real-time database systems to meet transaction deadlines. We also explore the concept of two-version data to increase the system concurrency level and to explore the abundant computing resources of multiprocessor computer systems. The capability of the proposed methodology is evaluated in a multiprocessor real-time database system under different workloads, database sizes and processor configurations. It is shown that the benefits of the priority cap in reducing the blocking time of urgent transactions are far greater than the losses involved in committing less urgent transactions. The idea of two-version data also greatly improves the system performance because of a much higher concurrency degree in the system     

Supplier selection using analytic network process and data envelopment analysis

The present study intends to present a supplier selection method, which also considers green indicators due to environmental protection issues, by using an analysis network process (ANP) as well as data envelopment analysis (DEA). ANP which is able to consider the interdependency between criteria releases the constraint of DEA that the users cannot set up criteria weight preferences. The model evaluation results for high-tech industry show that the proposed method can provide not only reasonable outcomes with a smaller number of decision making units, but can also provide more consistent results.     

The relationship between the eigenstructures and trajectory sensitivity of autonomous linear time‐invariant systems

Abstract

In this paper we examine the relationship between the state trajectory deviation caused by system parameter variation and the normality of the system matrix for autonomous linear time‐invariant systems. Starting from two rational definitions of the state trajectory deviation, we derive upper bounds for the state trajectory deviation. All the results developed indicate that the normality of the system matrix is the dominant factor in the trajectory sensitivity to the system parameter variation.     

Stability of schur polynomials under coefficient perturbation

Abstract

In this paper, we are concerned with the stability robustness of characteristic polynomials with perturbed coefficients for linear discrete‐time systems. An upper bound on the allowable coefficient perturbation of a Schur polynomial with retaining stability is obtained. The proposed upper bound is directly formulated in terms of the polynomial under consideration and its value can be determined by numerical computation. We also provide a sufficient condition for the stability of interval polynomials.     

Magnetic-to-digital converters using single-amplifier-based second-order delta-sigma modulators

In this paper, two magnetic-to-digital converters (MDCs) using single-amplifier-based second-order delta-sigma modulators (DSMs) are presented to detect the dc magnetic field. The proposed second-order DSM required only a single-operational amplifier to achieve the second-order noise shaping. Both the proposed circuits have been fabricated in a 0.5-/spl mu/m CMOS DPDM process, and the resolution of 11 bits can be achieved. The measured sensitivities are 1.486 and 0.459 mV/mT, and the minimum detectable magnetic fields are 0.6 mT and 0.4 mT for the MDC with and without the pre-amplifier, respectively. Both the measured nonlinearities are smaller than 1.3% within the range of /spl plusmn/ 100 mT.     

Material and technology developments of the totally sputtering-made p/n GaN diodes for cost-effective power electronics

Mg-doped GaN (Mg–GaN) films have been deposited on Si (100) substrates by radio-frequency reactive sputtering technique with single cermet targets. The targets can be made by hot pressing the mixture of metallic Ga and Mg powders and ceramic GaN powder. X-ray diffraction results showed that Mg–GaN films had a wurtzite structure with a preferential nonpolar $ m - \left( {10\bar{1}0} \right) $ growth plane. Mg–GaN with 10.2 % Mg has transformed into p-type conductivity and has the carrier concentration of 9.37 × 10¹⁶ cm^?3, the highest mobility of 345 cm² V^?1 s^?1, and the highest conductivity of 3.23 S cm^?1. The band gap of Mg–GaN films retrieved from the absorption spectra is 2.93–3.06 eV. Furthermore, we have also fabricated a totally sputtering-made and cost-effective GaN diode with the ideality factors of 5.0 and 4.9 for the as-deposited and the annealed, respectively.