Minia University, 61519 El-Minia. Egypt
Kanazawa University, Japan
We report on analyses of the operation characteristics and intensity noise of semiconductor lasers utilized as pumping sources of optical fiber amplifiers. The phenomenon of strong optical feedback (OFB) suffered by the pumping laser is analyzed. The analyses are based on a numerical approach of time-delay laser rate equations. The analyses are performed in terms of the instantaneous fluctuations of the laser intensity, bifurcation diagrams, phase portraits, and the relative intensity noise (RIN) spectra. Influences of the external fiber-cavity length on the laser dynamics and RIN are explored. The results indicate that the low-frequency RIN is well suppressed even under the levels of the solitary laser when the length of the fiber cavity decreases, where the laser operates in either pulsation or continuous wave. The operation becomes almost chaotic associated with enhanced RIN levels in the extreme end of long external cavities.
Technical University of Moldova, Republic of Moldova
Kanazawa University, Japan
University of Durham, UK
An investigation of phenomena of self-pulsation and excitability of blue-violet tandem lasers with saturable absorber has been carried out. Bifurcations, which are at the origin of these phenomena, have been identified. In order to control the laser dynamics, different laser designs have been presented. Finally, an agreement between results of numerical calculations and experimental data on self-pulsating laser operation was shown.
Multimedia University, Melaka Campus, Malaysia
This paper proposes modeling of a shunt active power filter (APF) for harmonic and reactive power compensation in three-phase system using power system blockset (PSB). Existing complex mathematical or Simulink simulation model of an APF system has been replaced by PSB model. Novelty of this paper lies in the generation instantaneous line reference current waveform using virtual phase-locked loop (PLL) block. The compensation scheme based on sensing instantaneous load and compensation currents only, an approach different from conventional methods, which require the knowledge of harmonics and reactive volt-ampere requirements of the load. Pulse width modulation (PWM) pattern generation is based on carrierless hysteresis based current control to obtain switching signals. Simulation results demonstrate the applicability of the PSB approach. The proposed system improves supply power-factor to units and reduces total harmonic distortion (THD) of supply currents below 5 %, the limit imposed by IEEE-519 standard. even with unbalanced source voltage.
Tokyo Metropolitan University, Japan
Tokyo Metropolitan University, Japan
Interpretation of surface electrostatic potential measurement by Kelvin probe force microscopy (KFM) is discussed and a technique of evaluating accurate contact potential difference is reported. It is essential to estimate variation of effective contact potential difference varied with probe-sample distance. It is also important to set the scanning frequency as low as possible. By using this method, the contact potential difference of Al against Au coated probe was evaluated by fitting measured data to a theoretical calculation taking the cantilever effect into account.
Sher-e-Bangla Agricultural University, Bangladesh
The convergence characteristics of the complex least-mean-squares (LMS) algorithm are subject to the distribution of the eigenvalues of the covariance matrix of the filtered reference signal. In general, the length of the adaptive filter chosen is as long as possible to achieve a better cancellation. Often it is practically impossible to calculate the eigenvalues and to investigate the convergence characteristics of the adaptive filter for actual applications because it requires a great deal of computations when the length of the adaptive filter is long. In this paper we treat a triple reference complex LMS algorithm countering three independent periodic noise source through adaptation. We presented a theoretical analysis (an explicit expression of reflection coefficients controlling the convergence behavior has been derived based on input covariance matrix and product matrix) in order to show the condition required to ensure the convergence in the mean-square error. The convergence is derived using Inverse Levinson-Derbin Algorithm and minimum phase property of prediction-error polynomials. Results of computer simulations of the convergence analysis of triple-reference complex EMS algorithm agreed well with the theoretical results.
University of Science, Malaysia
Uiversity of Science, Malaysia
Uiversity of Science, Malaysia
This paper describes a design of a multihop WDM router for ring networks and its implementation on FPGA (Field Programmable Gate Array). It is implemented on FPGA to evaluate the complexities of the algorithm on hardware. The design is divided into 3 main blocks; input module, path controller module and output switching module. The throughput of the system designed is 2.285Gbps and it can operate up until 5GHz of data input. Using Xilinx ISE software, the designs are successfully translated, mapped, routed and placed onto BurchED FPGA Demo Board. A test bed for evaluating the design is constructed on B5-X300 Board that occupies 300K gates XC2S300E FPGA which is supported by Xilinx Webpack tools. In the prototype, optical interconnection is replaced with an electrical interconnection. The FPGA chip is equipped with a lookup table that generates input data to supply data vectors. The outputs are subsequently observed for the corresponding data signal using a logic analyzer.
University of Science, Malaysia
Uiversity of Science, Malaysia, Engineering Campus, Malaysia
This paper describes the design of a digital front-end implemented in a software defined radio terminal. The designed and implemented digital front-end is to be used in a multi-standard wideband receiver. The simulation undertaken demonstrated that GSM and DECT standards specifications are met by a multiplier less digital quadrature down-conversion and multi-rate filtering composed of a 5th order comb filter, an inverse sine filter and a generic FIR filter. A fixed point architectural design was defined and a hardware resource efficient FPGA implementation results are reported.
Multimedia University, Cyberjaya, Selangor, Malaysia
Multimedia University, Cyberjaya, Selangor, Malaysia
Multimedia University, cyberjaya, Selangor, Malaysia
This paper proposes an application of emotion recognizer system in telecommunications entitled Voice Driven Emotion Recognizer Mobile Phone. This design implements voice to image media conversion scheme. The idea behind this system is to combine speech processing and AI to convert the emotion in voice information to facial expressions. This is realized by using emotion recognizer system that extract emotion features in the voice, recognize it and select the corresponding facial expression images from image bank. Since it only requires audio transmission, thus it can support video communication at much lower bit rate than the conventional videophone. Two subjective evaluations have been conducted to verify that voice can be used to detect emotion and to find out the importance of voice and facial expressions information in emotion recognition by human. The result of these experiments would justify the importance of the proposed system.
University Sains Malaysia, Engineering Campus, Malaysia
University of Science, Malaysia, Engineering Campus, Malaysia
An ion-sensitive field effect transistor (ISFET) based pH sensor has been designed for biomedical applications. In the design and characterization of an ISFET pH sensor, the ISFET model was characterized and a final design has been evolved with the assistance of the Tanner tools software. To provide a better understanding of pH ISFET as a biosensor, the C-V characteristics, and temperature dependence of an ISFET and pH sensitivity of Electrolyte-Insulator-Semiconductor in response to different pH was examined. The insulator, Aluminum oxide (AI203) has been applied as a pH sensitive layer. The ISFET was matched with a metal oxide field effect transistor (MOSFET) at a differential input stage of a CMOS operational amplifier and realized in a 0.8 m CMOS technology. From the output of an ISFET operational amplifier, the pH sensitivity is approximately 54.8 mV per pH.
Multimedia University, Malaysia
Multimedia University, Malaysia
This paper focuses on developing a scheduling method using linear programming for an Environmental Stress Testing (EST) operation. It has several tests and a schedule is developed by using minimized time at various operation stages. This is done by using typical linear programming and subsequently a schedule is arranged in a Gantt chart form. Constraints pertaining to the operation have also been developed. The schedule developed from the model has been tested in a real EST operation with favorable results obtained. Seventeen jobs were evaluated and the difference between calculated schedule and actual total flow time is less than 0.6 hrs. which computes to a very small error percentage. Thus this LP model can be used to schedule more jobs for this type of operation and determine the entire completion time.
Zagazig University, Egypt
Suez Canal University, Ismailia, Egypt
Traditional feed-forward neural networks are static structures, which simply map input to output. A method for predicting a new artificial network weighting function is devised. Using these predicted weighting functions, time series are derived. In the applications investigated, forecasting country population and May equation, this method outperformed all standard methods of neuralnetwork prediction.
Multimedia University, Malaysia
Multimedia University, Malaysia
Multimedia University, Malaysia
Drilling is the most important and frequently performed cutting procedure in the machining process. Metal removing process is becoming increasingly more complex, demanding and experiences an unprecedented growth. It has been reported that, one-third operation of material removal processes performed in industry is drilling operation. The paper deals with the measurement and the analysis of tool wear at different cutting conditions and parameters as per the model designed and tested according to factorial design method. Total of sixteen experiments were carried out to complete the research by using two different make twist drills (tool X and tool Y) possessing same specifications. The variables selected for tool wear were cutting speed, feed, machining time and thrust force. The designed model is to be tested by the R square analysis. The aim of the present work is to identify suitable parameters, the monitoring of which will enable the prediction of drill failure. The relative comparison of tool wear for tool X and V is to be done by observed values and analytical values, namely by statistical analysis and inverse coefficient matrix method. Later, tool validation is to be carried out to verify which is the better tool (X or Y) by residual analysis.
