Xudong Ding

PMV-based fuzzy algorithms for controlling indoor temperature

A fuzzy control strategy of the indoor temperature while maintaining the occupants thermal comfort is presented using the concept of the predicted mean vote (PMV) index. The PMV index is taken as the setting point of the controller and its feedback value is calculated from the PMV model based on the measured temperature and humidity. The difference value of PMV between the setting point and the feedback value is employed as the input of Fuzzy controller. Compared with the traditional temperature control methods, the proposed algorithm takes into account the influences of humidity parameters and wind parameters. It can achieve the energy saving by raising or reducing the indoor temperature according to the variant ambient conditions while maintaining the occupants thermal comfort.

Cooling Coil Unit dynamic control of in HVAC system

In this paper, a dynamic Cooling Coil Unit (CCU) model is firstly developed by extending the CCU engineering model [1], and by combining the model with the mass and energy balance equations. Unlike other existing CCU models for dynamic control, this modeling method with only six model parameters is relatively simple and exactly captures the nonlinear characteristics over a wide operating range of CCU without requiring much calibration effort and geometric specification, which is very convenient in real time engineering control practice. Afterward, the nonlinear model of CCU is linearized using Jacobian matrix method and PID-action controller as linear control systems are developed on linear model to adjust the outlet air temperature and outlet chilled water temperature. Experiments on a centralized Heating, Ventilation and Air Conditioning (HVAC) pilot plant are conducted to show that the method is robust and gives an accurate match to real performance over the wide operating conditions.

An arc fault diagnostic method for low voltage lines using the difference of wavelet coefficients

It is difficult to distinguish between fault arc and similar arc generated by the special load during normal working condition using the existing arc fault detection method. In this paper, a new arc fault detecting method of fast wavelet transform based on multi-resolution analysis is proposed. In the method, the sampling loads current was decomposed to low frequency signal and high frequency signals using the Mallat algorithm, and the mean and its difference of the reconstructed wavelet high frequency coefficients are treated as the criteria for arc fault diagnosis. Compared with the existing detection methods, this method can significantly reduce the computational burden and has high diagnostic reliability. The current characteristics of various loads are analyzed in normal or abnormal situations by the experiment to verify the accuracy of the method. The experimental results show that, the detection method can differentiate between fault arc and similar arc accurately, and the identification ability for specific loads is enhanced. The detection method can be widely used in low voltage power supply and distribution system to improve the diagnostic accuracy of the arc fault circuit interrupter.

A hybrid water-cooled centrifugal chiller model

This paper proposed a hybrid model for water cooled centrifugal chiller. The modeling method takes advantages of both physical and empirical modeling approaches and can accurately predict performance in wide operating range and in real-time, which can significantly reduce the computational burden and increase the prediction accuracy. The model is verified with the experimental data taken from a testing system. The testing results show that the proposed model can predict accurately the performance of the real-time operating chiller. The developed models will have wide applications in operational optimization, performance assessment, fault detection and diagnosis.

Design of an ARM9-based embedded industrial personal computer system

A design method of slot-embedded industrial personal computer (IPC) system based on ARM9 is presented in this paper. This method includes the design of hardware structure and software management platform of the IPC system. The hardware structure, which includes PCI communication module, man-machine interface module, Ethernet communication module and CAN bus communication module, is addressed in detail. The Linux operating system is employed as the software management platform, and a dual-core structure is used to study its real-time performance. The proposed system has the merit of low cost, strong versatility, stable and friendly interface. It will be widely used in the field of industrial control.

Hybrid dynamic modeling of the evaporator for the development of the advanced optimal control strategies

A hybrid model of evaporator used in air conditioning and refrigeration systems is proposed to present the dynamic behavior of the two phase flow evaporators. The model is formulated as process fundamental governing equations based on the energy and mass balance, and thermodynamic principles, while some constants and some variables which vary very little as time goes on, such as cross-sectional areas, mean void fraction, the derivative of the saturation enthalpy with respect to pressure, etc., are lumped into several unknown parameters, which are obtained by identifying the experimental data using nonlinear least squares method. The method takes advantages of both physical and empirical modeling approaches and can accurately predict the transient behaviors in real-time, which can significantly reduce the computational burden. The greatest merits of this model are the order of the model is very low and all the state variables can easily be measured, which are very suitable for model based controller design. The model validation studies on an experimental system show that the complete dynamic model developed in Matlab/Simulink can well predict the system dynamics. The developed models will have wide applications not only in controller design, but also in transient behavior analysis.

McCTRP: A cross-layer tree routing protocol for multichannel wireless sensor networks

Single channel wireless sensor networks may be unreliable when the channel of choice is either unstable or interfered. Previous work has shown that multi-channel solutions could effectively improve network reliability and deliver higher throughput as well. While a number of multi-channel medium access control schemes have been proposed, there are not much work on routing protocol design addressing the unique challenges multi-channel schemes are facing. In this paper we present a multi-channel cross-layer tree routing protocol. Our contribution includes: Adaptive beaconing corresponding to network topology; Beacon-driven, send-data and receive-data driven link quality estimations; and synchronized MAC and routing table management. Our protocol has been implemented on a testbed consisting of 53 nodes deployed in a 5-story building. Experimental results show that our approach provides fast convergence rate, stable topology and over 99.8% data transmission reliability.

A design of Network Prepayment Meter Reading System based on ESAM

A design of Network Prepayment Meter Reading System based on Embedded Secure Access Module (ESAM) is presented in this paper. Instead of user card which is used widely in the design scheme of prepayment system in recent years, ESAM module is introduced to act as e-wallet and the security module in the meanwhile to avoid the problems caused by information mediums such as IC card. The paper discusses the basic structure of the design, analyses its constituents, and elaborates strategy of data transfer. Real-time data transfer and secure method of transmission realize the functions of remote meter reading and remote recharge, improve systems security and reliability, and form a kind of highly efficient prepayment management mode.

A novel TDMA and multi-hop MAC protocol in cluster-based wireless sensor networks

In this paper, a novel TDMA and multi-hop medium access control protocol for cluster-based wireless sensor networks is presented. The communication protocol between cluster head and cluster nodes is developed from the Lightweight Medium Access Protocol (LMAC), but it makes up the defect of the poor network scalability of LMAC which cause from the fixed number of sensor nodes by adding a request slot in time frame and a request section in each work slot. The advantage of the protocol is the inherent energy-efficiency due to the lack of collisions. In addition, the multi-hop mechanism has been developed between cluster head nodes and base station to ensure long-distance information transmission.

A modified hybrid model of heat exchanger based on fouling effect

Hybrid model is a simple and accurate model for stable heat transfer process. Its theoretical basis shows that it is inappropriate to be applied to system with severe coefficient drifting. However, coefficient drifting is normal phenomenon in power and chemical industrial due to fouling. In this paper, a modified hybrid model of heat exchanger is proposed. The derivation of system is based on heat transfer balance and fouling principle of the heat exchanger. Considering fouling effect, a comprehensive model is derived. The catalog results with experiment data show that the proposed model can predict accurately the real-time performance of heat exchanger with error less than 3%. This model can be used in heat exchanger with high fouling risk for operational optimization, performance assessment and device maintaining.