Advanced Materials Research Vols. 875-877

Abstract: There are many methods of diamond wheel dressing,broadly divided into mechanical dressing and special processing trimmed two categories.This article describes several different EDM dressing diamond grinding wheel technology and divided into two categories namely:different medium EDM dressing diamond grinding wheel and EDM assisted dressing diamond grinding wheel technology. Summarize recent wheel dressing technology research advances at home and abroad.Elaborated EDM dressing key issues to be addressed, and further research.

Abstract: A novel way of three dimensional (3D) chip stacking has been designed in a view to improve heat dissipation across the layers. Chip stacking using vertical interconnections forms microscale channels for coolant to circulate through the gaps. Solder-based self-assembled (SBSA) 3D structures have been designed as posts on simulated through silicon vias (TSVs) to prove the processing concept. The processing of SBSA structures using a low temperature solder alloy and dip soldering method is described. Additional processing steps to fabricate interconnected 3D structures were demonstrated. Mechanical grinding of the 3D structures shows that soldered SBSA structures were void free and robust enough to be used as a connection post for chip stacking. SBSA structures provide a solder bump that serves as a connection path in the integration of dissimilar electronic technologies. Conventional copper posts, developed in a previous project, can be an effective approach to integrated circuit (IC) stacking. However, the SBSA post provides more variety in size and shape with a potential to serve as a reservoir for solder to aid in chip bonding. The solder bumps are heat resistant and uniform thicknesses were obtained across a large array of SBSA structures. The electrical durability of SBSA posts were determined by completing I-V measurements after thermal treatments. Fabricated SBSA posts were subjected to thermal cycling with temperatures ranging from room temperature to 300 °C. The interconnected SBSA posts are shown to be stable until 165 °C with little variation in measured resistance.

Abstract: This paper presents modelling techniques for Lithium Iron Phosphate (LiFePO4) battery in an electric vehicle. Artificial intelligence techniques namely multi-layered perceptron neural network (MLPNN) and Elman recurrent neural network are devised to estimate the energy remained in the battery bank which referred to state of charge (SOC). The New European Driving Cycle (NEDC) test data is used to excite the cells in driving cycle-based conditions under varied temperature range [0-55]°C. Accurate SOC prediction is a key function for satisfactory implementation of Battery Supervisory System (BSS). It is demonstrated that artificial intelligence methods can be effectively used with highly accurate results. The accuracy of the modeling results is demonstrated through validation and correlation tests.

Abstract: Green energy (GE) is natural energy that does not endanger humankind. Thus, precise knowledge about GE is very important to the future of humanity. The development of GE has been focused on renewable energy that avoids the emission of greenhouse gases. This paper proposes a technology forecasting (TF) model of GE technology that accurately explains GE. In this study, we retrieve patent documents concerning GE for application in our experiment, and we conduct patent analysis and simulation modeling in order to construct a TF model of GE technology. To verify the performance of our model, we forecast future aspects of GE technology.

Abstract: The need of energy is increasing enormously day by day and presently it is being fulfilled mostly by depleting energy resources like coal and petroleum based fuels. This situation pushes mankind to search for novel green technologies which can convert efficiently even low grade heat energy into useful energy. Thermoelectric generator (TEG) promises to be clear technology to generate electricity. TEG uses temperature gradient between source and sink to generate electricity. In this study, performance of commercially available thermoelectric module was studied using a specially designed cross flow heat exchanger. The heat exchanger was optimized previously using commercially available CFD package Ansys CFX. The efficiency of thermoelectric module was calculated by taking figure of merit and Carnot efficiency into consideration. The results indicate that the commercially available TEG used in this study, which is made of Bismuth Telluride performs efficiently at higher temperature difference and value of figure of merit is around one at maximum efficiency.

Abstract: Decreasing energy consumption and advancing thermal comfort are the most important aims of building engineering. Previously reported studies by many researchers have found that different usages of convective heat transfer coefficient (CHTC) correlations in heating system simulations have considerable impacts on calculated heating load in buildings. Hence, correct utilization of CHTCs in real size room enclosures has great importance for both energy consumption and thermal comfort. In this study, a modeled room was numerically heated from one vertical wall and cooled from the opposite wall in order to create a real room simulation. While cooled wall simulate heat losses of the room, heated wall simulates the heat source of enclosure. Effects of heated and cooled wall temperatures and characteristic length on CHTC and Nusselt number in the enclosure were numerically investigated for two (2-D) and three dimensional (3-D) modeling states. CHTCs and Nusselt numbers of a real size room with the dimensions of 6.00 by 2.85 by 6.00 were found with FLUENT CFD and graphics of change were drawn. As result, difference between 2-D and 3-D solutions was found approximately 10%. This was attributed as the effect of air flow pattern effects over other surfaces in the enclosure that can not be counted at 2-D solutions. The change of CHTC at different characteristic lengths was illustrated as well.

Abstract: The purpose of this work is to develop a pretreatment process of lingo-cellulosic ethanol production from narrow leaves cattail (Typha angustifolia) by using alkali catalysis with the response surface methodology (RSM) as a central composite design (CCD). The first step, LiOH, NaOH, and KOH were used as catalytic alkali for preliminary test. Second, the suitable alkali from first step was selected to optimize of pretreatment condition of three independent variables (alkali concentration, temperature, and residence time) that varies at CCD five codes (-2, -1, 0, 1, 2). Sodium hydroxide (NaOH) is the proper alkali because it could increase cellulose more than KOH and nearby LiOH while it is cheapest. RSM result shows the optimized pretreatment condition based on cellulose increased which obtained from this study that is NaOH 5 % w/v at 100 °C and residence time for 120 min. Beside, this condition was analyzed using an ANOVA with a second order polynomial equation after eliminated non-significant terms. At the optimized conditions, cellulose increased, hemicellulose decreased and weight recovery were achieved 77.81%, 80.59, and 41.65%, respectively. Moreover, the model was reasonable to predict the response of strength with less than 5% error.

Abstract: Alumina and zirconia are important materials for energy and optical applications. In this study, the effect of thermal cycling on grain size and residual stress was reported. Residual stress was measured using X-ray diffraction (XRD) sin2ψ method for the as-received and the samples after thermal cycling up to 900 cycles. For alumina, the measured residual stress is approximately 96 MPa in tensile for the as-received material, and increases to its highest value of 480 MPa after 650 thermal cycles. The residual stress decreases from 480 MPa to 96 MPa in tensile with increased thermal cycling from 650 to 900 cycles. The crystallized grain size calculated from the diffraction pattern shows that the mean crystallized grain size is about 93 nm for the as-received and increases to 232 nm after 650 thermal cycles. This result is consistent with the enlarged grain size observed by scanning electron microscopy for the alumina after 650 thermal cycles reported earlier. With continued thermal cycling up to 900 cycles, the crystallized grain size is greatly reduced to 104 nm. It suggests that evolution of the crystallized grain size is correlated with the residual stress. For yttria-stabilized tetragonal zirconia (Y-TZP), the mechanical properties at room temperature, are consistent with the property values provided by the manufacturer. The Young’s modulus of shows a non-linear inverse relationship with increasing temperature. The degradation of the Young’s modulus mostly occurs prior to 400 °C and to a less extent in the temperature range of 400 °C up to 850 °C. The Vickers hardness number for the as-received Y-TZP material decreases to a very small extent after 560 thermal cycles and increases approximately 2%, after 1200 thermal cycles. This is consistent with the trend of the Young’s modulus for thermal-cycled specimens.

Abstract: On the perspective of constant development, a major objective of today’s international strategies – the exploitation of nonpolluting resources becomes a very important aspect. Geothermal energy represents one of the renewable energy resources. The exploitation of geothermal resources of low enthalpy with the aim of producing electric energy is a well extended direction of development. The paper is dedicated to the simulation of processes and performances within equipments which build up a GPP having as a destination the exploitation of low enthalpy geothermal deposits. After the short presentation of the actuality subject and the structure of GPP we pass on to the draft modules for the equipments from the GPP structure, with the aim of specific processes simulation. By using the programming medium Matlab/Simulink we apply the model for a GPP which will function according to pre-established conditions. The obtained result after simulation are verry good, and the most important parameter wich is followed is the efficiency of the plant. The results for this parameter is high for this type of power plants.

Abstract: In this paper, a mode control strategy for a two-mode EVT hybrid electric vehicle (HEV) is proposed,considering transmission efficiency and mode change quality. First,speed and torque characteristics are analyzed by establishing relevant equations of two transmission mode. Next,the optimal operation mode is selected from the viewpoint of the transmission efficiency,when it is higher at a given speed ratio.Then,two scheme of operation sequence of clutch/brake are compared,and a control algorithm of synchronous control of two MGs and engine is suggested to reduce speed difference between both end of the clutch and torque fluctuation. A vehicle simulation based on Matlab/Simulink was performed to testify the mode change control algorithm of the dual-mode EVT HEV,and the simulation results showed that the mode control strategy for the dual-mode EVT HEV gave acceptable performance.