Cambridge University, UK
Using Geometric Algebra, Maxwell's classic equations with sources are derived as a necessary consequence of the symmetry of embedding a '3+1' spacetime into a '3+3' spacetime. In this work, two orthogonal temporal dimensions linking time to mass energy augment traditional time. These extra dimensions form a plane defined by a bi-vector i which acts as a classic imaginary i for '3+1' spacetime. 'Harmonic' variations in transverse time give zero rest mass in free space for complex electromagnetic fields E and B. Real fields and sources arise from averaging over a contour in the transverse time enclosing poles and zeros that are linked to positive and negative charges. Possible applications are considered.
Minia University, Egypt
Kanazawa University, Japan
Intensity and frequency noises of semiconductor lasers in optical disc systems are analyzed. We focus on optical feedback noise generated clue to reflection of laser radiation from an optical disc. The analysis is based on numerical integration of time-delay rate equations of lasers. The bifurcation diagrams and spectral profiles of noise are used to characterize the noise problem. Influences of injection current, distance of the disc-to-laser, and optical feedback-induced phase change on noise properties arc discussed. The results show that noise levels are significantly enhanced when chaos is induced, and are sensitive to the feedback-induced phase change.
University of Toronto, Canada
McMaster University, Ootario, Canada
The article presents a comparative study of the Kaplan-Meier nonparametric approach with the two well-known parametric lifetime distributions, namely, log-normal and two-parameter Weibull distribution. To illustrate the methods of estimation and for the purpose of comparison, two numerical examples have been presented after generating two type I censored samples by simulation. The conclusions from examining our two examples suggests that a parametric approach produces better estimates in terms of the standard deviation of the estimates, provided that one can nofind a distribution that fits the data well. The findings will motivate the researchers analysing their survival statistics not to blindly go for nonparametric approach without first giving some effort to cheek their data against parametric models.
Humboldt-University Berlin, Germany and
Technical University of Moldova
Kanazawa University, Japan
University of Durham, UK
Phenomenon of excitability of blue-violet lasers with saturable absorbers has been discussed. A bifurcation analysis of laser dynamics demonstrates the existence of the excitability. The optimum conditions for this phenomenon are investigated and the possibilities for applications are discussed.
University Teknologi Malaysia
Universiti Industri Selangor, Jalan Zirkon, Malaysia
Putrajaya. Malaysia.
Future telecommunications systems demand space-limited application. Hence, the research work on antenna has grown tremendously. In addition, there is a need for a single antenna that can operate for more than one frequency. The existence of a single, rather than two antennas for transmitting and receiving, is highly desirable. Thus, the problem of limited space can be overcome. Consequently, the total manufacturing cost can be reduced. One example of a dual-operation antenna is on a moving vehicle where the user can detect his/her location while simultaneously communicating with another user. The relevant frequencies could be Global Positioning System (GPS) of 1.575 GHz and Global System for Mobile (GSM) 1.8 GHz. The tri-operation antenna is needed for access Wireless Local Area Network (WLAN) of 2.45 GHz and two GPS frequencies of 1.227 G1-Iz and 1.575 GHz. This paper presents two designs of such single dual operation (RPRem) and tri-operation (Rsn) antennas having printed low profile configurations. The MathCAD software has been used for computing and correlating the relevant design formulations. A simple expression for each design has also been successfully developed. The basis of the designs is the basic rectangular patch. The RPRem antenna is a rectangular patch of size 48 mm by 35 mm perturbed with embedded two L-section structures. The optimum feed location was determined to be 14.5 mm from the antenna edge. The measured antenna operates well near the designed frequency of operations. The Rsn antenna is a multilayer rectangular patch having three equal-size radiating elements; each operates at a different frequency within the specified bands. The feed line is located at the non-radiating edge. The three layers of the antenna have identical radiating sizes of 48 mm by 37 mm. The measured antennas exhibit well-matched frequencies of operations that correspond to the simulated antennas and theory.
National University of Singapore, Singapore
National University of Singapore, Singapore
National University of Singapore, Singapore
This paper is an introduction to application Response Surface 11ethodology (RSM) in optimization of designs. The princ1es of the method are explained and a procedure to build a second order RSM model is described. An example of application in motor design is given. It shows how RSM can be combined with Finite Element Method (FEM) to model the motor parameters of an Interior Permanent Magnet Synchronous Motor for optimization constant power speed range. A very wide speed range has been achieved using this method in an Interior Permanent Magnet Synchronous Motor (IPMSM).
Multimedia University, Malaysia
Multimedia University, Malaysia
Multimedia University, Malaysia
This paper introduces a three-level hierarchical production planning and scheduling approach developed and implemented in a resin factory. Our approach extends the existing formulation and determines optimal number of monthly batches that need to be scheduled, a process known in this industry as batching of orders. At the first level, a mixed-integer linear programming model is used to solve the aggregate plans where setups occur. At the second level, a weighted-integer goal-programming model is developed to disaggregate the aggregate plans. At the third level, a job-sequencing model formulated as mixed-integer programming model that deals with sequencing of batches. Real industrial data is used to test and validate the proposed models.
Sathyabama Deemed University, Chennai, India
Sathyabama Deemed University, C'hennai, India
Sathyabama Deemed University, Chennai, India
Microwaves are used in industrial applications which would greatly reduce the time consumption encountered by conventional method. One of the industrial applications of microwave is in the detection of dry rubber content in the natural latex obtained from Hevea brasiliensis. This application becomes relevant in the current scenario of fast rising price of rubber. The conventional method of finding dry rubber content is highly time consuming and rubber growers find it expensive. The cost of the rubber directly depends on the dry rubber content. This paper deals with a sample linear relationship between the dry rubber content and the attenuation of microwave signal using free space technique.
Multimedia University, Malaysia
Multimedia University, Malaysia
This paper presents a modified analytical model based on mean value analysis (MVA) technique and virtual lot clustering method for a probabilistic re-entrant stress testing line. The objective is to determine the total cycle time and the mean throughput rate of the reflow screening process for a given number of lots. We analysed a five-stage queuing system with re-entrant lines into the second stage under various probabilistic routing conditions. The analytical and simulation results were compared. The results obtained can be used by operation managers for their decision making.
Science College, Suez Canal Univ., Ismailia 41522, Egypt
Zagazig Univ., Zagazig, Egypt
Science College, Suez Canal Univ. -Ismailia 41522, Egypt.
Digital mammogram is currently one of the most important tools used for early detection of breast cancer. For achieving the best performance of using digitized mammograms in cancer diagnosis, two main problems may be investigated. The first problem Is the classification of benign, malignant, and normal mammograms. The second one is related to the classification of cancerous lesions. In this paper, supervised classifier for these problems is developed. The diagnosis processes are done by transforming the data images into a feature vector using multiresolution wavelet basis. This vector is used as the feature tailored toward separating each of those classes. The suggested model consists of artificial neural networks designed for classification of the mammograms. Radiologist-labeled images were used to evaluate the diagnosis system. The results are very promising and show possible guide for future work.
Faculty of Computer and Informatics, Zagazig University, Egypt
Science College, Suez Canal Univ. -Ismailia 41522, Egypt
Suez Canal University, Arish. Egypt
Suez Canal University, Arish. Egypt
The objective of this research is to demix number of input data vectors or streams that are mixed and demix them back to their original dimension. In this paper the independent component analysis (ICA) was adopted with the classical Gram-Schmidt orthogonalization process.
