空调水系统变流量节能控制及实验研究

本文研究了阀位控制，设计了可实现变流量控制的实验平台。通过对阀位控制实验数据及其他控制理论结果的对比分析，认为该控制法具有节能性强的特点，易于推广。     

Electrocatalytic oxidation of methanol on mono and bimetallic composite films: Pt and Pt–M (M = Ru,Ir and Sn) nano-particles in poly(o-aminophenol)

Mono and bimetallic composite catalysts have been formed by a three-step process, whereby the surface of aluminum electrode was pretreated upon immersion into a Pd(NH₃)₄Cl₂ solution (p-Al), was subsequently coated with a thin poly(o-aminophenol) (PoAP) layer by potentiodynamic electropolymerization of o-aminophenol and Pt and Pt alloys nano-particles were finally dispersed into the PoAP film by electrochemical methods. The electrocatalytic properties of the platinum doped (Pt/PoAP/p-Al) and Pt alloys doped (Pt–M/PoAP/p-Al, M = Ru, Ir and Sn) electrodes towards the methanol oxidation were investigated by cyclic voltammetry and compared with the electrocatalytic properties of pristine Pt and Pt particles on pretreated Al (Pt/p-Al) electrodes. The enhancement of the electrocatalytic activity of the Pt nano-particles, when Ru, Ir and Sn, are co-deposited in the polymer is also studied in detail. The effects of various parameters on the electrooxidation of methanol as well as the long-term stability of doped electrodes have also been investigated.     

A model‐based fault detection and diagnosis strategy for HVAC systems

A strategy of fault detection and diagnosis (FDD) for HVAC sub‐systems at the system level is presented in this paper. In the strategy, performance indices (PIs) are proposed to indicate the health condition of different sub‐systems including cooling tower system, chiller system, secondary pump systems before heat exchangers, heat exchanger system and secondary pump system after heat exchangers. The regression models are used to estimate the PIs as benchmarks for comparison with monitored PIs. The online adaptive threshold determined by training data and monitored data is used to determine whether the PI residuals between the estimation and calculation or monitoring are in the normal working range. A dynamic simulation platform is used to simulate the faults of different sub‐systems and generate data for training and validation. The proposed FDD strategy is validated using the simulation data and proven to be effective in the FDD of heating, ventilating and air‐conditioning (HVAC) sub‐systems. Copyright © 2009 John Wiley & Sons, Ltd.     

Novel clay‐based nanobiocomposites of biopolyesters with synergistic barrier to UV light,gas, and vapour

This article presents novel solvent cast biocomposites of poly(lactic acid) (PLA), polyhydroxybutyrate‐co‐valerate (PHBV), and polycaprolactone (PCL) with enhanced barrier properties to UV light, oxygen, water, and limonene by means of incorporating an organomodified mica‐based clay grade. The TEM results suggested a good clay dispersion but with no exfoliation in the three biopolyesters. In agreement with the crystallinity data, which was found to generally increase with increasing filler content, oxygen but specially water and d ‐limonene permeability coefficients were seen to decrease to a significant extent in the biocomposites and an optimum property balance was found for 5 wt % of clay loading in the three biopolymers. With increasing clay content, the light transmission of these biodegradable biocomposites decreased by up to 90% in the UV wavelength region due to the specific UV blocking nature of the clay used. As a result, these new biocomposites can have significant potential to develop packaging films, coatings and membranes with enhanced gas and vapor barrier properties and UV blocking performance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A backoff strategy for model‐based experiment design under parametric uncertainty

Model‐based experiment design techniques are an effective tool for the rapid development and assessment of dynamic deterministic models, yielding the most informative process data to be used for the estimation of the process model parameters. A particular advantage of the model‐based approach is that it permits the definition of a set of constraints on the experiment design variables and on the predicted responses. However, uncertainty in the model parameters can lead the constrained design procedure to predict experiments that turn out to be, in practice, suboptimal, thus decreasing the effectiveness of the experiment design session. Additionally, in the presence of parametric mismatch, the feasibility constraints may well turn out to be violated when that optimally designed experiment is performed, leading in the best case to less informative data sets or, in the worst case, to an infeasible or unsafe experiment. In this article, a general methodology is proposed to formulate and solve the experiment design problem by explicitly taking into account the presence of parametric uncertainty, so as to ensure both feasibility and optimality of the planned experiment. A prediction of the system responses for the given parameter distribution is used to evaluate and update suitable backoffs from the nominal constraints, which are used in the design session to keep the system within a feasible region with specified probability. This approach is particularly useful when designing optimal experiments starting from limited preliminary knowledge of the parameter set, with great improvement in terms of design efficiency and flexibility of the overall iterative model development scheme. The effectiveness of the proposed methodology is demonstrated and discussed by simulation through two illustrative case studies concerning the parameter identification of physiological models related to diabetes and cancer care. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Influence diagnostics for multivariate GARCH processes

This article presents diagnostics for identifying influential observations when estimating multivariate generalized autoregressive conditional heteroscedasticity (GARCH) models. We derive influence diagnostics by introducing minor perturbations to the conditional variances and covariances. The derived diagnostics are applied to a bivariate GARCH model of daily returns of the S&P500 and IBM. We find that univariate diagnostic procedures may be unable to identify the influential observations in a multivariate model. Importantly, the proposed curvature‐based diagnostic identified influential observations where the correlation between the two series had a major change. These observations were not identified as influential using the univariate diagnostics for each asset separately. When estimating the bivariate GARCH model allowing for weights at influential observations, we found that the time‐varying correlations behaved differently from that implied by the model ignoring influential observations. The application therefore highlights the importance of extending univariate diagnostic procedures to multivariate settings.     

Towards Dynamic Drug Design: Identification and Optimization of β‐Galactosidase Inhibitors from a Dynamic Hemithioacetal System

A discovery strategy relying on the identification of fragments through resolution of a constitutional dynamic system, coupled to subsequent static ligand design and optimization, is demonstrated. The strategic design and synthesis of the best molecular fragments identified from a dynamic hemithioacetal system into static ligand structures yielded a range of β‐galactosidase inhibitors. Two series of structures mimicking the hemithioacetal motif were envisaged: thioglycosides and C‐glycosides. Inhibition studies provided important structural information for the two groups, and 1‐thiobenzyl‐β‐D ‐galactopyranoside demonstrated the best inhibitory effects.     

一种多功能频率测量系统

运用信号检测、控制与信息存储技术，用8位AVR单片机实现信号源的频率测试与电机控制。根据所测信号频率，采用PWM波实时调节电机的转速，实现光圈的开度控制。系统中PC机与AVR单片机间采用RS232串口进行数据通信．系统具有密码验证功能，满足安全要求。首先AVR单片机通过I^2C总线读取存储器中的密码信息，然后将其与PC机传来的密码数据进行比较。如果密码正确，则启动系统。设计语音播报功能，采用凌阳SPCE061单片机进行语音处理。系统以C语言编程，可读性较好，可移植性强．实验表明系统设计合理可靠，满足设计要求。     

Kinetic and morphological study of a magnesium ethoxide‐based Ziegler–Natta catalyst for propylene polymerization

BACKGROUND: Kinetic and morphological aspects of slurry propylene polymerization using a MgCl₂‐supported Ziegler–Natta catalyst synthesized from a Mg(OEt)₂ precursor are investigated in comparison with a ball‐milled Ziegler–Natta catalyst. RESULTS: The two types of catalyst show completely different polymerization profiles: mild activation and long‐standing activity with good replication of the catalyst particles for the Mg(OEt)₂‐based catalyst, and rapid activation and deactivation with severe fragmentation of the catalyst particles for the ball‐milled catalyst. The observed differences are discussed in relation to spatial distribution of TiCl₄ on the outermost part and inside of the catalyst particles. CONCLUSION: The Mg(OEt)₂‐based Ziegler–Natta catalyst is believed to show highly stable polymerization activity and good replication because of the uniform titanium distribution all over the catalyst particles. Copyright © 2008 Society of Chemical Industry