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Abstract: In this paper the comparison between the performance of a cross flow heat exchanger in wet and dry operation for air handling process has been investigated. In addition, a case study of application of the component to perform indirect evaporative cooling in a AHU was studied with the software TRNSYS.Using experimental data and an appropriate analytical method, energy saving performances of the system has been evaluated through the entire cooling season for a typical Mediterranean site. Results show that high energy saving potential can be obtained if the component is operated in wet operation in term of reduction of electricity consumption. [Copyright &y& Elsevier]

Abstract: The availability of solar radiation in phase with the seasonal as well as hourly cooling load profiles in most of the office buildings in the Mediterranean region, in addition to the large share of primary energy consumed for air- conditioning applications in office buildings create a high motivation for the utilization of solar cooling technology for such type of buildings. A solar heating and cooling system for an office building in Italy has been designed, installed and monitored within the framework of the EC co-funded project SOLERA aiming at developing highly integrated solar thermal heating and cooling system that is able to achieve a high solar fraction both for the heating and cooling seasons. The analysis of the system performance during 2011 is presented in this paper, with main focus on electricity consumption during summer. The analysis has been carried out according to the monitoring procedure developed within the frame of the IEA SHC Task 38. [Copyright &y& Elsevier]

Abstract: In this paper, the effect of material composition on the overheating protection performance of thermotropic systems with fixed domains (TSFD) is studied. Several thermotropic layers were formulated by variation of both, matrix material and thermotropic additive. Refractometry was applied in order to obtain refractive index data as a function of temperature of all material constituents and to screen wether material combinations are promising to formulate or not. Investigations concerning optical properties, switching temperature and switching process were carried out applying UV/Vis/NIR spectrometry. Morphological analysis was conducted with a Scanning Electron Microscope (SEM). Several TSFD showed reasonable light-shielding efficiency. Nevertheless further optimization of scattering domain size and shape is necessary to improve the light shielding performance. [Copyright &y& Elsevier]

Abstract: Nowadays, European policies are promoting low energy buildings because of the high amount of energy consumption of the building sector. Phase change materials (PCM) have been studied in building implementation as a passive system to reduce the energy demand. Based in the experience obtained in the experimental set-up of Puigverd de Lleida (Spain), this paper pretends to analyze experimentally the PCM performance in a scenario with internal thermal gains. The experiments were done in three different cubicles with the same internal dimensions. The selection of the constructive systems used in these three cubicles allows the authors to evaluate the impact of using PCM in a typical Mediterranean building. A domestic heat pump for summer and an electric radiator for winter were installed to control the internal temperature of the cubicles. The results of summer period experiments show that the PCM cubicle stored the heat produced by the internal loads limiting the heat dissipation to the outer environment. Therefore, the energy consumed by the HVAC system of the PCM cubicle during the cooling period is higher than that of the other cubicles that dissipated the thermal loads according to the thermal resistance of their envelopes. Therefore, the PCM selection should take into account not only the comfort temperature but also the activity and functionality of the building. [Copyright &y& Elsevier]

Abstract: Previous research studies conducted on building components containing a phase-change material (PCM) have shown a great potential for direct and indirect energy and cost savings in the building envelopes. In particular, PCM impregnated gypsum boards, one of the most popular application of PCMs in buildings, have been reported to reduce building cooling loads by 7−20%. However, in order to best design and optimize the PCM-enhanced building materials, it is critical to accurately characterize the dynamic thermal properties such as enthalpy curve, volumetric heat capacity, sub-cooling, hysteresis − of these PCM-enhanced components. In addition, test data on these dynamic characteristics is necessary for whole-building simulations, energy analysis, and energy code work. In the past, the only existing readily-available method of thermal evaluation of PCMs utilized the Differential Scanning Calorimeter (DSC) methodology. Unfortunately, this method required small and relatively uniform test specimens. This requirement is unrealistic in the case of many PCM-enhanced building envelope products. Small specimens are not representative of PCM-based blends with gypsum, concretes, fiber insulations, plastic foams etc., since these materials are often not homogeneous. In this paper, dynamic thermal properties such of a ½” thick PCM impregnated gypsum board are analyzed based on a novel dynamic experimental procedure: using the conventional HFMA. The gypsum board tested in this work contained 20−25% by weight of a microencapsulated PCM with latent heat of ∼120kJ/kg. First, the theoretical details of the dynamic HFMA (DHFMA) are described. In essence, top and bottom plates of the HFMA are set to the same temperature and heat flow signals from the corresponding heat flux meters are integrated over time to compute the enthalpy changes during a temperature step change. Volumetric heat capacity profile is determined by taking the slope of the enthalpy curve. A negligible sub-cooling and hysteresis is observed for the PCM impregnated gypsum board. In addition, thermal properties such as onset of melting and solidification, and sensible heat of the specimen when PCM was in solid and liquid state were also determined. Dynamic properties such as heat capacity profiles and peaks of melting and solidification cycles, and amount of sub -cooling as measured by DHFMA were found to be relatively close to the DSC results on the same microencapsulated PCM. [Copyright &y& Elsevier]

Abstract: The objective of Task 44 of the Solar Heating and Cooling program of the IEA is to assess performances and relevance of combined systems using solar thermal and heat pumps, to provide a common definition of performances of such systems, and to contribute to successful market penetration of these new promising combinations of renewable technologies. The Task is also Annex 38 of the Heat pump program and thus called T44A38. It gathers 12 countries and 55 participants.This paper presents the mid term results of the activity, which started in January 2010 and will last until December 2013. [Copyright &y& Elsevier]

Abstract: Large solar thermal systems (LSTS) are a promising market segment for solar energy. However, the realization of LSTS is more challenging compared to smaller plants, in both technical and economical terms. Permanent monitoring, data evaluation and fault detection during the operation of LSTS has shown by Fink et al. [3] and Peuser et al. [13] to be crucial for ensuring optimal performance. The only cost-effective way for permanent surveillance of LSTS operation is to make use of a computer-aided tool that performs as many steps as possible in an automated mode. The R&D project ‘IP-Solar’ developed the scientific basis and the technical fundamentals for such a system. This paper presents the current state of development emphasizing the methodology of the operation diagnostics. In particular, the algorithm-based approach, its implementation and testing are described in detail. [Copyright &y& Elsevier]

Abstract: Low emissivity coatings can significantly reduce radiative heat losses of glass panes for solar energy use. Their effectiveness is strongly dependent on their optical properties, which need to meet the requirements for the specific application. The paper analyses the performance of newly developed, highly transmitting and spectrally selective glass coatings based on transparent conductive oxides (TCO) for the use in flat plate collectors: Uncovered, single- glazed and double-glazed designs are taken into consideration. As functional layers both tin-doped indium oxide and aluminum-doped zinc oxide have been investigated. Collector efficiencies and annual collector yields are presented and compared to those of state-of-the-art collectors. Theoretical calculations are complemented by measurements on collector prototypes. The results show that a significant performance increase is accessible both in single-glazed collectors with low or non-selective absorbers and in double-glazed collectors with highly selective absorbers. [Copyright &y& Elsevier]

Abstract: Energy efficient HVAC solutions may be obtained by combining different energy sources – fossil and renewable – into single hybrid systems. This leads to a variety of system concepts with specific boundary conditions. As a consequence, the definition of a unique representation method and a standardized performance evaluation procedure is a challenging task. Currently, two international projects promoted by the IEA are dealing with the representation and the performance calculation of a particular category of hybrid systems, i.e. integrated solar assisted systems. The HPP Annex 34 “Thermally Driven Heat Pumps for Heating and Cooling”, whose goal is to reduce the environmental impact of heating and cooling by the use of thermally driven heat pumps, has solar cooling as one of the systems under investigation. The joint project between SHC and HPP Task 44/Annex 38 “Solar and Heat Pump Systems” is focused on different system combinations of solar thermal collectors and heat pumps. The scope of the present paper is to show a systematic methodology to represent and evaluate the energy performance of complex hybrid systems. The proposed approach is a joint effort of the on-going IEA activities and will be discussed regarding the mentioned solar hybrid systems. However, the final goal of the work is to provide a basis for a simple, fair and transparent comparison of all systems for heating and cooling, regardless of the technology. [Copyright &y& Elsevier]

Abstract: This study was to investigate the CO2 reforming under isothermal condition. The fuel conversion efficiency and hydrogen-rich gas production were enhanced via the oxidative dry reforming (ODR) from simulated biogas (50%-CH4+50%-CO2). This paper covers two subjects. The first was to investigate the CO2 conversion characteristics under various feeding molar ratios (e.g. H2/CO2 and O2/CH4 molar ratio). In the second, the whole performance index of the reformer was investigated. The experimental results demonstrate that the CO2 reduction capacity of methane is superior to that of hydrogen. This effect is clearer under higher reaction temperatures. The ODR reaction experiment results indicate that adding appropriate amounts of oxidants can increases the methane conversion and reforming efficiency. But, the excessive oxidizes could be reduce the CO2 conversion efficiency. Additionally, at high DR/ODR reaction temperatures, reverse water-gas shifting (RWGS) side reactions become signification, which can reduce CO2 to CO efficiently, thereby improving the CO2 conversion efficiency. Overall, the optimal methane conversion efficiency can reach 100% in ODR reaction (O2/CH4 molar ratio=0.5). The CO2 conversion efficiency is based on DR reactions (CO2/CH4 molar ratio=1) reaching between 57% and 95%. [Copyright &y& Elsevier]

Abstract: Benchmark refrigerated systems in the road transportation sector are powered by diesel, having operation costs of up to 6,000 €/y. This paper presents the development of an alternative refrigeration system based on fuel cells, with higher efficiency, reduced costs and independent of diesel price fluctuations. Energy load profiles have been analyzed and the fuel cell stack and auxiliaries are being modeled in order to dimension and design a balance of plant and control algorithms that ensure a safe and easy utilization. Additionally, a prototype shall be tested under different load profiles to validate the control strategies and to characterize the performance of the system. [Copyright &y& Elsevier]

Abstract: The gain of Metal Wrap Through (MWT) cells and modules in comparison to standard modules has been extensively reported in the past. Most studies are limited to Standard Test Conditions (STC), and outdoor performance is not regarded. This paper studies the outdoor performance and energy yield of back contact foil based MWT modules in comparison to standard modules.A big advantage is the very low series resistance of the MWT modules; its influence on energy yield is simulated and compared to standard modules for different locations throughout Europe. It is shown that the gain at STC conditions is largely translated into a gain in the produced energy.The gain is confirmed by outdoor measurements on two locations in Europe. It is shown that the monthly performance ratios of the MWT and H-pattern modules do not differ and thus the gain at STC is a good measure for the eventual gain in energy yield. [Copyright &y& Elsevier]

Abstract: Our commitment is the development of an industrial-grade Class AAA solar simulator based on LED technology . Presently, the LEDSim™ covers the full wavelength range of interest for Si-PV with an extension in the UV, matching AM1.5g from 350nm to 1100nm. To achieve user-defined target spectra we apply 22 different LED packages including several uncommon types. We present a measured spectrum tuned to AM1.5g. It follows from rare lifetime information for some LED species that we need to set a strong focus on reliability determination for our lightheads. In this paper we show how we confirm the lifetime promise of the LED technology with reliability testing. Modern design-for-reliability methods are taken into account in order to increase the reliability of the LEDSim™. Beam shaping and homogeneity are key functions of a sun simulator, and a large effort is made on achieving Class A homogeneity for each wavelength interval as specified in IEC 60904-9 . We are testing different kinds of LED optics and add mirror channels to achieve the best relation between homogeneity and intensity. [Copyright &y& Elsevier]

Abstract: The feasibility of the application of a spar-type wind turbine at a moderate water depth is studied in this paper. In the oil and gas industries, spar-type offshore platforms are widely applied in deep water. The same idea is used in offshore wind technology to present the Hywind concept based on a catenary moored spar in deep water. The draft of the spar limits the application of spar-type wind turbines in shallow water. However, it is possible to design spar-type wind turbines for moderate water depths. The present article studies the feasibility and performance of such a design. A spar-type wind turbine at a moderate water depth called “ShortSpar” is introduced in the present article. A catenary moored spar-type support structure is applied as a base for the 5-MW NREL land-based turbine. The power performance, structural integrity and dynamic responses of a 5-MW catenary moored spar-type wind turbine in deep water (DeepSpar) have previously been studied. In the present article, the responses of the spar-type wind turbines, ShortSpar and DeepSpar, are compared. The HAWC2 code is used to carry out the coupled aero-hydro-servo-elastic analyses. Different environmental conditions are used to compare the responses. A dynamic link library (DLL) is used to feed the mooring forces at each time step into the HAWC2 code. The force-displacement relationships are obtained from the Simo-Riflex code. The comparison of the responses of ShortSpar and DeepSpar in different load cases indicates the feasibility of implementation of spar-type wind turbine in moderate water depths. The results show that the spar-type wind turbine at a moderate water depth exhibits good performance, and its responses are reasonable compared with those associated with a spar-type wind turbine in deep water. The total mass (the structural mass plus the ballast) of ShortSpar is 35% less than the mass of DeepSpar, while the statistical characteristics of the generated power are almost the same for both spars. This mass reduction for ShortSpar helps to achieve a more cost-effective solution for floating wind turbines at a moderate water depth. [Copyright &y& Elsevier]

Abstract: The structural aspects of a 70 meter long blade in an upwind, horizontal-axis wind turbine were developed in this paper for use in a high wind speed location. A hybrid composite structure using glass and carbon fiber plies was created yielding a light-weight design with a low tip deflection. The blade was subjected to FEA studies to demonstrate its ability to withstand the extreme loading conditions as defined in the international offshore wind standard. The results confirmed the design to have acceptable performance with regard to tip deflection, maximum and minimum strains, and critical buckling load. Detailed descriptions of the structural components and ply layups are presented along with the resulting maximum and minimum strains and deflections. In addition, optimization techniques were introduced to provide insight for future studies with the blade. [Copyright &y& Elsevier]

Abstract: In the future, large offshore wind turbines are expected to reach a rating of 10 MW. To reduce the corresponding weight increase of the nacelle, research has started to focus on solutions to omit the step-up transformer in each turbine. Therefore this paper investigates a modular converter suitable for a special high power, transformer-less generator drive with 36 kV output DC-voltage. The drive consists of nine converter modules connected in series on the DC-side to obtain a high output voltage. Due to the series connection, extra care has to be taken to achieve equal voltage division between the converter modules. Therefore, a DC-voltage balancing scheme based on a droop control is proposed. The performance of the system will be demonstrated through simulations in EMTDC/PSCAD. [Copyright &y& Elsevier]

Abstract: The potential of contact passivation for increasing cell performance is indicated by several results reported in the literature. However, scant characterization of the tunneling layers used for that purpose has been reported. In this paper, contact passivation is investigated by insertion of an ultra-thin AlOx layer between an n-type emitter and a Ti/Pd/Ag contact. By using a 1.5nm thick layer, an increase of the minority carrier lifetime by a factor of 2.7 is achieved. Since current-voltage measurements indicate that an ohmic behavior is conserved for AlOx layers as thick as 1.5nm, a 1.5nm AlOx layer is found to be a candidate of choice for contact passivation. [Copyright &y& Elsevier]

Abstract: Linear Quadratic Gaussian (LQG) control methodology shows useful properties of good performance and robust-ness in controller design applied to wind turbine. Typically, in the design procedure LQG method is necessary to select weighting matrices in order to solve the Algebraic Riccati Equations and then get the matrices Kalman Filter gain and optimal state-feedback. In order to optimize a LQG control applied to Double-Fed Induction Generator in wind power system, a Genetic Algorithms (GA) adapted to get the best values of the element of weighting matrices is proposed in this paper. The performance indices ISE and ITSE are a good alternative to obtain the fitness function to design LQG controllers with GA. The simulation results show the high effectiveness of this optimal design method. [Copyright &y& Elsevier]

Abstract: Recently, various control models have been developed to optimize the performance of wave energy converters in order to enhance their long term economic value. Among others, the control of the all-electric Power Take Off (PTO) has been actively studied. This paper introduces the application of bio-inspired Ant Colony Optimization (ACO) metaheuristic as decision support for real-time wave energy extraction. It is found that the performance of the proposed algorithm is appealing as it is able to provide optimal parameter values to the control model within short interval. This provides fast-tuning capability to the PTO while sparing suffcient time for the WEC to respond to the continuously changing sea states. [Copyright &y& Elsevier]

Abstract: The synthetic jets have been identified as a promising technique for various fields of both dynamic fluid and aerodynamics, by using different numerical simulations which recently have been played an important role in their development. In the aim to provide the flow mechanisms by influencing both their visualization and their theoretical analysis provided by the implementation of the different validation code, several passive and active techniques have been studied to explore particularly their characteristics. The present work investigates the performance of the Moving Boundary technique which is one of many different computational tools implemented to reproduce the flow behavior of a 3D synthetic jet. The experimental work is a well stabilized test case used as a CFD benchmark by the CFDVAL 2004 workshop. The main feature of the present work is in use of a moving boundary implemented by use of generating computational mesh at every time step of the unsteady computation. Results are first intended to calibrate versus the measurement in order to be sure that phases are accordance. Several points and lines positions are chosen to compare the averaged velocity components. The preliminary results are encouraging and allow reproducing at least qualitatively the flow behavior animations of the synthetic jet. Nevertheless further improvements have to be added, mainly in grid generation and probably in turbulence model selection. The results given in this paper will be used for validating perspective computational studies to control the boundary layer separation. [Copyright &y& Elsevier]

Abstract: Nowadays a way to optimize photovoltaic systems consists in implementing distributed structures, implying the use of electronic devices. In this paper we show performances of improved DC-DC converters able to feed an inverter. Resulting efficiency allow us to consider parallel HVDC architecture connecting independently PV modules with low section wiring. [Copyright &y& Elsevier]

Abstract: The hybrid controls are the controls combining several techniques. Their purpose is to benefit from performance of each of these techniques. The control proposed in this paper is based on this hybrid approach; combining the performances of the controls which are based on the tools of the artificial intelligence (artificial neural networks and fuzzy logic) applied to control the single-phase induction machine without capacitor supplied by voltage source inverter. The application of this approach to the single-phase induction machine is a contribution to the study of this machine. Indeed, this type of machine has not yet taken its whole share from various works present until now, compared to the three-phase induction machine. The simulation results show the feasibility and good performance obtained by the proposed control. [Copyright &y& Elsevier]

Abstract: This paper presents the development of a novel solar-powered adsorption cooling tube. The tube consists of adsorbent bed (solar collector), condenser, and evaporator, all in one unit. Activated Carbon-Methanol is used as a working pair to suit cooling and refrigeration applications. From the experimental studies of the tube results all year round, performance and produced cooling are evaluated as well as recommendations and conclusions for best performance are presented [Copyright &y& Elsevier]

Abstract: The here presented applied research and development project is targeted to the development and application of new and improved techniques in plant design, performance analysis and process control. Hereto following the required steps are illustrated and the goals are outlined. The project covers the development of a previously patented anaerobic digestion process, adaption of flow cytometry as an analytical instrument and investigation of innovative ways of disposal of solid fermentation wastes. The preliminary experiences with a newly built research plant employing a novel anaerobic biogas digestion technique are discussed. In this paper the first outcomes concerning the construction and operation are discussed. A novel method of disposal of the fermentation wastes is also discussed and first results are shown. [Copyright &y& Elsevier]

Abstract: This paper shows that we can improve the performance of the auto-adjustable electric machines if a fractional dynamic is considered in the algorithm of the controlling order. This structure is particularly interested in the separate control of active and reactive power of the double-fed induction generator (DFIG) of wind power conversion chain. Fractional regulators are used in the regulation of chain of powers. Knowing that, usually, the source of DFIG is provided by converters through controlled rectifiers, all this system makes the currents of lines strongly polluted that can have a harmful effect for the connected loads and sensitive equipment nearby. The solution to remedy these problems is to replace the power of the rotor DFIG by a matrix converter which represents a THD less important. The structure of the adopted adjustment is tested using Matlab/Simulink and the results are presented and analyzed for a variable wind. [Copyright &y& Elsevier]

Abstract: Since its discovery, electrical energy represents one of the most decisive fields in any technology. In this paper, a comparative study between fixed hysteresis band current control (HBCC) and adaptive hysteresis band current control techniques in speed drive system is presented. These techniques control the variation of output voltage of the three phase rectifier. The theory and analysis of both the conventional fixed-HBCC and the adaptive HBCC which are the control techniques that operate at any condition with variable and constant switching frequency, are respectively developed. At the end, the performance of such control technique has been observed and discussed thanks to a simulation study carried with Matlab Simulink environnement. [Copyright &y& Elsevier]

Abstract: This article has carried on the analysis in view of the coal mine old communication network and the relay protection installment existence''s question, Proposed based on the OMAP platform to build a coal mine power system relay protection program, elaborated the OMAP platform coal mine relay protection principle, To design this equipment''s schematic diagram, and has carried on the performance introduction to this equipment''s main hardware constitution, this paper has developed the data acquisition function software flow chart, it provided the basis for the development new coal mine distribution network relay protection installment. [Copyright &y& Elsevier]

Abstract: In order to enhance the coefficient of performance of solar absorption refrigerator and analyse the system performance, it was necessary to collect the operation parameters in the system. This paper put forward to combine the technique of visual instrument and the characteristic of solar absorption refrigerator, using National Instrument''s product LabVIEW, to develop an effective data acquisition(DAQ) system. This DAQ system can realize the real-time data acquisition of temperature, water flow rate and pressure as well as data transmission, processing, and display, in addition to provide users with historic data inquire. It saved a lot of labor power and material resources so that it made measurement more convenient and fast. [Copyright &y& Elsevier]

Abstract: In order to improve the photoelectric efficiency and solar energy utilization of PV module, a set of photovoltaicdouble resource heat pump (PV-DHP) is designed in this paper. Through calculation of system performance, the result shows that the efficiency of PV-DHP system can be up to 4.86 and photoelectric efficiency increases highly. According to economic compare, it is known that the operation cost of PV-DHP is 61.6% of air source heat pump, 16.6% of oil-fired boiler and 19.5% of electric heater. [Copyright &y& Elsevier]

Abstract: This paper presents a practical multicast routing, which dynamically transforms a conventional multicast tree into a multicast mesh and increases the opportunities for coding by applying double direction network coding scheme. The simulation shows the proposed algorithm is a practical multicast routing, and it has better performances by comparing with ODMRP and MORE-M in terms of coding gain and packet delivery ratio. [Copyright &y& Elsevier]

Abstract: There is increasing interest in micellar-polymer flooding because of the need to increase oil production from depleted and waterflooded reservoirs. Using horizontal wells for injection and production in a micellar-polymer flood process, higher sweep efficiency is expected compared with the use of conventional patterns by vertical wells. This paper presents an analysis of how the overall performance of a micellar-polymer flood process is influenced by the well pattern using horizontal injector and producer in different configurations. Results from the study have demonstrated that significant amount of oil can be recovered additionally and injectivity was remarkably improved by utilizing a combination of horizontal wells. The improvement of injectivity through a horizontal injection well was higher when it was combined with horizontal producer parallel to the injector. [Copyright &y& Elsevier]

Abstract: In view of sustainable development, it is imperative that mineral admixtures be used to replace cement in the concrete industry. This paper presents a laboratory study on the performance of steam cured concrete by adding mineral admixtures. Performance of the concrete mixes was determined with short and longterm tests, which include compressive strength, dry shrinkage, anti-chloride permeability and pore structure. The test results, in general, showed that mineral admixtures improved the performance of concretes. Ground granular blast furnace slag (GGBS) contributed to both short and long-term properties of concrete, whereas Fly ash (FA) shows its beneficial effect in a relatively longer time. Adding of both GGBS and FA significantly improved the microstructure of steam cured concrete, and contributed more to the improvement of transport properties of concretes. [Copyright &y& Elsevier]

Abstract: According to a majority of static evaluation and without common significance problems of regional environmental performance evaluation, evaluation indicator system of regional environmental performance is established in view of evaluation indicator system design principle, which is composed of environmental investment, operational performance, environmental condition and environmental profit. A dynamical model on regional environmental performance evaluation is put forward in this paper, which is combined with the basic idea of DEA and fuzzy integral assessment method. In order to provide the reasonable basis for local government to take corresponding measures to improve their environmental performance level, we carry through empirical analysis about regional environmental performance of 8 typical western regions in china and draw conclusion. [Copyright &y& Elsevier]

Abstract: In view of characteristics of working medium and villages buildings, the paper took pebble as material to store collected solar energy and studied the regenerator performance by numerical simulation (Matlab Programming) and experimental research. To comprehensively consider heat-exchange performance and operating cost, average regenerative power and air flow resistance were taken as target functions. Research results showed that the larger cross section velocity and length of pebble bed, the larger average heat storage power and air flow resistance. However, it''s different for pebble diameter. The smaller pebble diameter, the larger average heat storage power and air flow resistance. So, pebble diameter was suggested to be 0.04∼0.08m. The determination of cross section velocity and length of pebble bed would need to take into account volume flow and regenerator structure. [Copyright &y& Elsevier]

Abstract: There are many methods available for Load frequency control in an interconnected power system. This paper deals with tuning of PID controller for Load frequency control. A two area thermal power system is considered for study. Both the areas are equipped with PID controller. Parameters of these PID controllers are obtained using Particle Swarm Optimization. A comparative study on tuned values has been presented to verify effectiveness. Ziegler-Nichols method is used for tuning of parameters for comparative study. The simulation results demonstrate the effectiveness of the designed system in terms of reduced settling time and oscillations. MATLAB/SIMULINK was used as simulation tool. [Copyright &y& Elsevier]

Abstract: Wireless communication is currently the most dynamic field with the invention of new technologies. Presently one of the main challenges in the wireless communication field is to combat fading. At the receiver, the signal may be lost completely due to destructive addition of multi paths signal components. Generally effect of fading is analyzed with channel compensation using different diversity combining schemes such as selection diversity, equal gain combining and maximal ratio combining techniques. Selection diversity is one of the preferred schemes due to its simplest implementation process. However, often channel estimation may not be perfect because of changing nature and other factors like correlation between the signals etc. The main aim of this paper is to observe the effect of imperfect channel estimation on the performance of the receiver. Analysis has been done for channel estimation along with selection diversity combining. Also, receiver may not be synchronized always with transmitter giving some phase errors. Such error is also incorporated along with selection diversity for performance evaluation of the system. [Copyright &y& Elsevier]

Abstract: The significant amount of kinetic energy comes out of runner in reaction turbines and the draft tube is used to recover this kinetic energy into useful pressure energy. The energy recovery in draft tube depends on its design and magnitude of velocity components at runner exit. Further the amount of kinetic energy coming out of runner depends on the solidity of runner as well as its rotational speed. Hence draft tube is important component of turbine next to runner. In this paper, 3D viscous turbulent flow simulation has been done in the complete flow passage of Francis turbine using commercial Computational Fluid Dynamics (CFD) code for three runner solidities at different rotational speeds. The draft tube performance parameters in non-dimensional form are computed from simulation results and the effects of runner solidity and operating speed on draft tube performance are discussed. The simulation results are also compared with the experimental results for validation and are found to be within reasonable accuracy. [Copyright &y& Elsevier]

Abstract: The hybrid power sources, particularly type renewable is one of advanced solutions in the field of energy including wind-photovoltaic type, designed to ensure reliability of system operation or chain energy conversion with better management and control. In this paper, we analyze the modeling and simulation of an energy conversion system based on a double-fed induction machine (DFIM) powered by a hybrid renewable source. The results obtained are very advanced and satisfactory. [Copyright &y& Elsevier]

Abstract: In order to control the position of hybrid stepper motor and improve its performance, direct torque control strategy is adopted. The main idea of this paper is to present the implementation of an emotional controller for position control of hybrid stepper motor drive. The proposed controller is called Brain Emotional Learning Based Intelligent Controller (BELBIC). This controller is a computational model of emotional processing mechanism in the brain. The effectiveness of the proposed BELBIC controller-based hybrid stepper motor drive is verified by simulation results. [Copyright &y& Elsevier]

Abstract: In classical methods only average torque of the stepper motors is controlled which causes high speed and torque ripple. In order to control the torque instantaneously and improve the performance of the hybrid stepper motor, direct torque control strategy is used in this paper. Then by taking model reference adaptive system scheme, which uses the hybrid stepper motor itself as the reference model, speed of the motor is estimated. The sensorless control of hybrid stepper motor based on MRAS is built and simulated with Matlab software. The results show that this control technology is simple and effective and accuracy of the estimation is considerably high. [Copyright &y& Elsevier]

Abstract: Considering the increasing role of microturbines in distributed generation of combined heat and power (CHP), the localization of microturbine design and manufacturing technology has received great importance in Iran. Providing a complete and comprehensive algorithm can be a major step in reaching the goal. In this paper, we present the cycle for the thermofluids design of a 100 KW microturbine which is carried out at the Niroo Research Institute of Iran to simultaneously generate both electricity and useful heat. The characteristics of this system are as follows: revolution speed of 47750rpm, single shaft, natural gas as fuel, single stage radial turbine/compressor and annular combustion chamber. Based on the thermodynamic characteristics of the cycle, the characteristics of different components of microturbine are determined throughout the study. According to the determined values, we expect the cycle to achieve an efficiency of approximately 13% without the recuperator and 25% with the recuperator. It must be noted that the designed microturbine is going through the final assembly stages at the time and the performance test has not been conducted yet. Therefore, the over-all characteristics curve of the system was not available at the time of preparing this article. [Copyright &y& Elsevier]

Abstract: In this paper, performance of the liquid desiccant dehumidification system in evaporation coolers was investigated by the Second Law of Thermodynamics analysis. This system was designed and manufactured for this purpose. Lithium chloride (LiCl), as liquid desiccant, and a packed bed column were used for dehumidification. The described system includes a part for processed air simulation in various temperatures and humidities. Entropy generation of the liquid desiccant dehumidifier was analyzed based on the second thermodynamic law. The effect of inlet parameters of the dehumidification column on the entropy generation was also investigated. The results showed that the entropy generation was highly dependent to operational conditions and inlet parameters of the desiccant dehumidification column. [Copyright &y& Elsevier]

Abstract: Water-saving retrofitting of existing residential buildings can not only ease the country''s water shortage, but also owns strategic significance to keep sustainable development of construction industry. Firstly, this paper described the currently used water-saving measures of buildings. And then, according to the analysis of domestic and international water-saving retrofitting of buildings and related evaluation, using AHP and Gray Comprehensive Evaluation, it developed a comprehensive evaluation index system of water-saving retrofitting of buildings,and provided a more comprehensive and objective evaluation method for water-saving retrofitting of exiting residential buildings. [Copyright &y& Elsevier]

Abstract: The results of an experimental work carried out to evaluate the effect of palm oil methyl esters, also known as palm oil diesel (POD) and its emulsions as alternative fuel on unmodified indirect injection diesel engine''s wear and lube oil performance are presented in this paper. Half throttle engine with constant 2500 rpm setting was maintained throughout the wear debris and lube oil analysis such as for a period of twenty hours for each fuel system. The sample of lube oil was collected through a one - way valve connected to the crankcase sump at the interval of four hours. When the engine warmed up, first sample has collected immediately. The same conventional lubricating oil SAE 30 was used for each fuel system. To measure wear metal debris and lubricating oil additives depletion of used lubricating oil, Multi element oil analyzer (MOA) was used. To measure the viscosity of lub oil an ISL automatic houillon viscometer (ASTM D445) has been used. Very satisfactory results have been obtained by comparing the lub oil analysis results of Ordinary Diesel and Palm Oil Diesel and their emulsions with 10 percent water by volume. In crankcase oil samples, accumulation of wear metal debris was lower with Palm Oil Diesel and emulsified fuels compare to baseline Ordinary Diesel fuel. Both Ordinary Diesel and Palm Oil Diesel emulsions with 10 per cent water by volume showed promising trends for resisting wear. [Copyright &y& Elsevier]

Abstract: The robustness of multiple access schemes such as Orthogonal Frequency Division Multiplexing (OFDM) as needed for the wireless communication system is well proven. There is now an increasing demand to transmit digital video signals and other digital information in an indoor environment. A solution to avoid the prohibitive cost of installing dedicated wires for this application is to transmit data over the power line. As the medium voltage and low voltage power lines transmit such high frequency communication signals, these signals undergo attenuation due to line loss and impedance mismatch because of branches and loads. Thus a signal which is received at the receiver end is not a replica of transmitter end signal, signifying of symbol error. In order to understand more about OFDM technique of transmission of data, in this paper we have carried out the performance analysis of transmission of digital data over indoor power lines using OFDM. The simulation results of the performance analysis show that 16-QAM symbol constellation is fully recovered and symbol error can be reduced significantly by suppressing some weak carriers. [Copyright &y& Elsevier]

Abstract: The performance evaluation plays a more and more important role in the modern enterprise management, and the method of evaluation system on enterprise performance is always an important question in the theory and practice. So this paper set up a scientific, reasonable performance evaluation index system which was especially suitable for the small and medium third party logistics enterprise from the four levels of financial, customers, business and innovation. Meanwhile, according to the index system, it gave a performance evaluation with the Chinese access logistics corporation. The results showed that the construction of the index system was reasonable, and the evaluation results also were reliable. [Copyright &y& Elsevier]

Abstract: For the shortcoming of single air source heat pump, single solar energy heat pump and switch solar-air dual heat source heat pumps, a new solar air two source heat pump was proposed. Then, the performance of the solar air two sources heat pump was studied by experiment. According to the characteristics of heating performance of the solar air two sources heat pump, two important concepts were proposed. The two concepts were “the two heat sources effectively compound heat transfer temperature difference” and “the max two heat sources effectively compound heat transfer temperature difference”. And in this paper, the influence on the heating performance of the two heat sources effectively compound heat transfer temperature difference in different solar hot water flows, and the effect of the two heat sources effectively compound heat transfer temperature difference were researched by experiment and analyzed. The experimental results show, the max two heat sources effectively compound heat transfer temperature difference increased with solar hot water flow decreasing and it decreased with the outdoor air temperature increasing. The solar hot water flow has more influence than the outdoor air flow. [Copyright &y& Elsevier]

Abstract: In this paper, a practical method to design a robust controller for pressure of boiler in Mashhad Power plant using H∞ is proposed. To achieve a good performance of an industrial boiler in order to reduce fuel consumption rate and reaching higher efficiency, dynamic variables such as fuel flow, air flow and pressure of boiler must be controlled. However this dynamic model may associate with uncertainties. Uncertainties in mentioned model are caused by lack of knowledge about the dynamics of the system, pay load changes, and air flow. Thus, application of robust control methods for high precise control of pressure is inevitable. In the first step plant is identified by using experimental data by the mean of converting into a group of linear time invariant (LTI) uncertain plants. After representation of the uncertain dynamic system in general control configuration and modelling the parametric uncertainties, nominal performance, robust stability and robust performance against disturbances are analyzed by the concept of structured singular value μ. Then, using genetic algorithm an optimal controller is designed for tracking problem and disturbance rejection. This procedure gives a satisfactory controller at the presence of model perturbations. For more comparisons, quantitative feedback theory (QFT) as a well known robust control approach is also applied to the plant. Finally, nonlinear simulation has been carried out and two controllers are compared. Both optimal robust controllers guarantee robust performance of the system against the uncertainties and result in desired time responses of the output variables. By applying H∞ robust control, system tracks the desire reference inputs in a less time and with smoother time responses. [Copyright &y& Elsevier]

Abstract: There are two winding methods for the interior permanent-magnet synchronous motor for vehicle traction: concentrated winding and distributed winding. Both have merits and demerits, and both influences the motor''s performance. In this paper, designs of concentrated- and distributed-winding motors with the same capacities are presented, and each motor''s characteristics were analyzed using the finite-element method. [Copyright &y& Elsevier]

Abstract: Reactive power optimization plays a significant role in the operation of wind farm grid intern connection to maintaining voltage stability and system reliability. Genetic algorithm (GA) is an efficient method which can be applied in reactive power optimization to reduce power loss and improve power quality. However, traditional GA has some defects, such as slow convergence and prematurity. For improvement, the paper modified decoding method, genetic operators, crossover and mutation probability, iteration stopping criterion based on the theory of Catastrophism. A reactive power optimization techniques based on improved genetic algorithm (IGA) of wind farm is such presented. Simulation results for Chinese Mongolia Huitengliang Power Plant show that the proposed method has satisfied global performance, high convergence speed and stable convergence performance, so it is suitable to solve the optimal reactive power planning. [Copyright &y& Elsevier]