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In this paper, the semi-theoretical kinetics equations were proposed and the electro-dewatering experiments of sludge were conducted to analyze the kinetics laws of electro-dewatering under constant voltage and constant current. The results showed that the decline rate of moisture content remained stable under constant current, while the decline rate of moisture content kept decaying in the operating mode of constant voltage. No matter in what kind of operating mode, the change in decline rate of moisture content was consistent with that of filtrate flow rate, both of which were essentially dependent on the current. The follow-up electro-dewatering tests under constant voltage were carried out by using three different kinds of sludge to understand the mechanism of electro-dewatering. The results showed that the main parameters that controlled the electro-dewatering behavior were measured current, conductivity and zeta potential of sludge. When treated at 30 V, sludge C reached the lowest moisture content, owing to its higher conductivity and zeta potential. However, the poorer electro-osmotic effect of sludge C led to its higher average unit energy consumption. By comparison, an increase of applied voltage was more effective for electro-dewatering process of sludge C but at the expense of higher energy consumption, while sludge A and B were more inclined to improve the electro-dewatering effect by extending the dewatering time. Finally, the derived equations were demonstrated by the experiments, which could provide guidance for the practical applications.

Variable refrigerant flow (VRF) systems are easily subjected to performance degradation due to refrigerant leakage, mechanical failure or improper maintenance after years of operation. Ideal VRF systems should equip with fault detection and diagnosis (FDD) program to sustain its normal operation. This paper presents the fault diagnosis method for refrigerant charge faults of variable refrigerant flow (VRF) systems. It is developed based on the principal component analysis (PCA) feature extraction method and the decision tree (DT) classification algorithm. Nine refrigerant charge schemes are implemented on the VRF system in the laboratory, which contain the normal and faulty refrigerant charge conditions. In addition, data of the online operating VRF systems are collected in this work. Firstly, data from both experimental VRF system and online operating systems are pre-processed by outlier cleaning, feature extraction and data normalization, because the original data of the VRF system usually has poor quality and complex structure. Secondly, the fault diagnosis model based on the PCA-DT method is built using the data of the experimental VRF system. In this step, the PCA method is used to obtain a new data sample which includes four comprehensive features, then the new data sample are randomly split into training and testing sets as the input of DT classifier for fault diagnosis. Thirdly, the advantages of the PCA-DT method is validated using the experimental data of different fault severity levels. Results show that the combined use of PCA and DT methods can achieve better fault diagnosis efficiency than the single decision tree method. Further, the robustness of the PCA-DT method in online fault diagnosis is verified using the data from online VRF systems. The online VRF systems have the same or different number of indoor units as the trained (experimental) VRF system. The PCA-DT method also shows desirable goodness on the online fault diagnosis process. In this sense, this work provides a promising fault diagnosis strategy for refrigerant charge faults of VRF system application.

Construction model for traditional performance appraisal index pay attention to financial perspective and Disregard corporate social responsibilities cannot adapt to enterprises development. To meet the need of overall evaluating enterprises sustainable development ability, this paper first proposed the idea to introduce a corporate social responsibility strategy into performance evaluation, analyzed the basic principles of overall evaluating Enterprises strategic performance in the view of social responsibility. Then proposed three dimensions include corporate social responsibility, internal processes; at last bring social responsibility into Balanced Scorecard as an important dimension to build a new three-dimensional Evaluation model.