Abstract: In this paper, the characteristics of long-wavelength vertical-cavity surface-emitting laser (VCSEL) lasing at 1550 nm have been studied based on the influence of the oxide aperture radius. Using the oxide confined VCSEL model, we examine the static operations taking into account the carrier-noise, photon-noise and phase-noise including feedback of the external cavity. From the simulation, several important laser characteristics such as threshold gain, threshold current density and external quantum efficiency have been evaluated. Our results show that by scaling the oxide aperture radius, we are able to obtain an optimal oxide aperture radius in enhancing the VCSEL’s characteristics.

Abstract: Discharging the ANG storage tank from 3.5 MPa to a depletion pressure results in temperature fall within the ANG vessel. The fall of storage pressure was from a rapid to slow rate along with constant rate of gas removal while the temperature was falling drastically with depressurization as a result of heat of desorption and partly due to pressure drop. In the present study the characteristics of ANG storage system during discharge has been studied. When gas was discharged at discharge rate 1, 5, 10 l/min, a much drop in bed temperature occurred. Bed Preheating was investigated as a solution to enhance the discharge process and to avoid much amount of gas retained (not desorbed). Improvement in the amount desorbed and capacity was recorded as a result.

Abstract: Elementary mathematical formulas governing the power developed by the Pelton turbine and design were deduced in early 1883. At that time the principal sources of loss are identified as the energy remaining in water after being discharged from the bucket, The heat developed by impact of water in striking the bucket, The fluid friction of the water in passing over the surface of the bucket, The loss of head in the nozzle, The journal friction the resistance of the air. It was assumed that the effect from of above all the losses were negligible when deriving the Mathematical formula governing the performance of the Pelton wheels. And also it was assumed that the all the water escapes from the bucket with the same velocity. Among the various analytical studies that had been done on Pelton turbine hydraulics less attention has been paid to the friction along the buckets. In this paper the effect of bucket friction was analyzed using Boundary Layer theory.

Abstract: We propose a scalable architecture for a Discrete Cosine Transform (DCT) computation engine based on Single Instruction stream and Multiple Data stream (SIMD) - Array Processors. Each pixel of an input matrix is distributed across a 4-way connected Processing Element (PE); and a frame comprises several such PEs making it possible to compute as many pixels as the number of PEs in a frame. Tripling such frames allows us to compress a colored image as efficiently as any gray-scale image. We specifically target least possible computations by completely replacing a floating-point unit by Look-up-Tables (LUTs) and an efficient implementation of an 8-bit multiplier is presented. By making use of nine processors, arranged in a matrix of the order 3x3, we manage to compute nine coefficients in less than nine clock cycles resulting in a tremendous Data-Rate (DR) of 1.4Gbps at the cost of 967 slices. Performance is analyzed using SPARTAN III FPGA (Field Programmable Gate Array) and a comparison with a previously proposed systolic architecture is presented.

Abstract: One way to reduce uncertainty in problem solving and decision making is by seeking the advice of an expert in related field. On the other hand, when we use computers to reduce uncertainty, the computer itself can become an expert in a specific field through a variety of methods. One such method is machine learning, which involves computer algorithm to capture hidden knowledge from data. In this research, a problem solving scenario for a metal cutting industry which faces some problems in determining the end product quality of Manganese Molybdenum (Mn-Mo) pressure vessel plate is investigated. Therefore, several real life machining scenarios with some expert knowledge input and machine technology features were incorporated. Three significant design parameters were used, namely; cutting speed, gas pressure and power. Artificial Neural network (ANN) has an ability to derive meaning from complicated data, and can be used to extract patterns and detect trends that are too complex to be noticed by either humans or other computational techniques. Therefore, prediction of laser machining cut quality, namely surface roughness was carried out using machine learning techniques based on Quick Back Propagation Algorithm using ANN. Experimentally observed responses were used to train, map and optimize the network algorithms before the best architecture was selected. Ten different architectures and models were tested and finally the best 3-8-1 model was finalized based on R square values. The model was then fed with new sets of machining parameters to experimentally validate the model’s ability in predicting the cut quality. The findings were found to be very promising and yielded excellent accuracy for both model and experimental validation reaching almost 88% and 92% respectively.

Abstract: Reactor components including fuel assemblies and heat exchanger tubes are beam-type structures with natural or forced boundary conditions or mixed type boundary conditions. It is difficult to model such systems accurately as it consists of both thermal fluid flow behavior and structure of hollow fuel rods. An attempt is made to de-couple the problem into thermal fluid flow and structures. First, a vibration analysis of the fuel rod is carried out resulting in the form of natural frequencies and corresponding mode shapes. Then, three-dimensional transient thermal fluid flow transport equations are solved across a hollow cylinder with specified boundary conditions. This gives a transient temperature profile or the vorticity of flow around the fuel rod in the form of fluctuating force having a certain frequency. A comparison is made between the fluctuating force frequency of the coolant fluid and the hollow rod natural frequency; a phenomenon called lock-in is obtained in both directions, resulting in much larger amplitude of resonance vibration of the rod. The natural frequencies of the fuel rod for a 300 Mwe PWR Nuclear Power Plant are calculated and compared with numerically calculated Turbulence Induced Vibration (TIV) fluctuating force frequencies. The present paper is very useful to evaluate the fuel rod vibration with various boundary conditions. An important result is obtained for the variation in the vorticity along the axis; it is found that in the range 0-700 mm, the vorticity is in the range 0-5 Hz i.e. it approaches the first-mode natural frequency. A similar trend is seen towards the end of the flow channel when the vorticity is 25 Hz corresponding to the third mode of natural frequency. Further numerical investigation is needed with variable coolant velocity and temperature.

Abstract: In traditional method of farming, human labors were required to visit the greenhouse at specific time and need to check the humidity level and temperature level manually. This conventional method is considered time consuming and needs a lot of work and effort. Therefore this research focuses on developing a system that can remotely monitor and predict changes of temperature level in agricultural greenhouse. The objective of the research is to develop a remote temperature monitoring system using wireless sensor and Short Message Service (SMS) technology. The proposed system has a measurement which capable of detecting the level of temperature. This system also has a mechanism to alert farmers regarding the temperature changes in the greenhouse so that early precaution steps can be taken. In this research, several tests had been conducted in order to prove the viability of the system. Test results indicated that the reliability of the system in propagating information directly to the farmers could be gained excellently in various conditions. increases the value of resistance. But it not happens in capacitance behavior as firmness change. The capacitances were decreased as firmness improved.

Abstract: One of the main objectives of aircraft and automotive manufacturers is related to improvement of the crash behaviour of lightweight structures. The absorbed energy is an important parameter for the development of the vehicle passive security concept. In present paper, the composite laminate of conical shell structures subjected to slip loading are studied by using finite element method. ANSYS/LS-DYNA finite element software was used in this analysis, the effect of geometrical on energy absorption chrematistics and failure modes are investigated. The kinetic energy and energy absorption capability is calculated. In the case of composite, the crush-induced damage including matrix cracking and delamination are predicted by the failure mechanism and damage history is plotted. Five types of semi-vertex angle (?) of conical tubes of 4, 8, 12, 16 and 20 degrees are considered in this work. The effects of various semi-vertex angles of conical shell on the energy absorption capability and failure mechanism are considered. Results of energy absorption and failure modes of composite collapsible structures demonstrated that the conical shell it has semi-vertex angle (?) of 8 degrees absorb high specific energy and different crushing failure modes during the crushing analysis under slip loading.

Abstract: Optical solitons are considered as natural bits for telecommunications as they have the tendency to maintain their shape over transoceanic distances because of interaction between nonlinearity and anomalous group velocity dispersion. However, depending upon the individual pulse width, inter-pulse spacing and loss in the fiber, co-propagating solitons do interact and share energy. It is therefore imperative to investigate the soliton pulse interaction before implementing them in a high speed optical communication system. Incorporating the mathematical model based on the Nonlinear Schrödinger (NLS) equation and using the split-step Fourier transform method; we have conducted various simulation experiments to investigate the interaction between adjacent pulses of equal amplitude, in-phase solitons co-propagating in dispersion shifted fibers. The simulation results show that, solitons after traveling a certain distance get attracted and evolve as a giant pulse of double the amplitude of the individual pulse and if propagated further, simply get separated as if they have walked through each other. The simulation results reveal that, a careful choice of the pulse and fiber parameters can be helpful in avoiding the soliton interaction which limits the channel capacity .

Abstract: An integrated farming system is probably the most benign agricultural production system from the environmental perspective, where crop and livestock production are in balance with nature. However, over the years the increased applications of fertilizers, pesticides and grazing intensities, have undoubtedly led to significant potential of river pollution. This study was carried out to determine the impacts of integrated farming towards Langgas River water quality. The frequency of sampling was three times per day in three months continuously. The physical and chemical water quality analyses were carried out according to the APHA procedures. The water quality parameters studied were phosphate, ammonia-nitrogen, biological oxygen demand (BOD), chemical oxygen demand (COD), turbidity, temperature, dissolved oxygen (DO), pH, conductivity and total suspended solid (TSS). From the overall finding, the study indicated that integrated farming effected Langgas River water quality but in the value is still within the acceptable limit. From the mean concentration results, Langgas River is free from organic contamination. Meanwhile, from the statistical analysis, only five parameters showed significant differences (p<0.05).

Abstract: Yttrium iron garnet (YIG) substituted lanthanum ions (La3+) Y3-xLaxFe5O12 were synthesized at different temperatures. The effect of calcination temperature on crystalline structures was investigated by using X-ray diffraction (XRD). The results show that the crystallization of the samples La-substituted YIG x=0.0 and x=0.5 is more completed when the calcination temperature increases. However, Fe2O3 phase was formed in the sample with La substitution of x=1.0 when the temperature increases. The sizes of substituted YIG particles calculated from Scherrer equation were ranged from 29 to 71 nm and it was found increased with the increasing of calcination temperature.

Abstract: Brakes and tires are the major contributors for catastrophic failure of ground vehicles. Braking system is the utmost important besides tire to ensure the safety of users and vehicle. Ensuring good condition of brake lining is very crucial to ensure the efficiency of the braking system, where, the worn off brake lining not only endangers life but also damages the entire brake associated parts such as hub, disk, shaft, etc. In this paper, Malaysian made luxury car Proton Perdana V6 brake pads were investigated to be embedded with a lining wear limit alert system. The current spring steel alert system has some drawbacks where, the alerting sound is only activated while the car moves and secondly, when the car is on move, rarely the alerting sound reaches the driver. Therefore, a critical investigation of the existing pads manufactured in Malaysia and their characterizations are conducted to identify the most suitable sensor spot on the brake pad. Later, a micro sensor is embedded into the pad and fully tested on a specially designed test rig. The evaluation of thickness, hardness, layer properties and critical wear region has enabled the spotting of exact sensor location. The embedment of the micro switch was successfully done and tested to be very efficient in alerting the driver upon reaching the maximum lining wear limit.