Md. Rajibul Islam

Chronology of Fabry-Perot Interferometer Fiber-Optic Sensors and Their Applications: A Review

Optical fibers have been involved in the area of sensing applications for more than four decades. Moreover, interferometric optical fiber sensors have attracted broad interest for their prospective applications in sensing temperature, refractive index, strain measurement, pressure, acoustic wave, vibration, magnetic field, and voltage. During this time, numerous types of interferometers have been developed such as Fabry-Perot, Michelson, Mach-Zehnder, Sagnac Fiber, and Common-path interferometers. Fabry-Perot interferometer (FPI) fiber-optic sensors have been extensively investigated for their exceedingly effective, simple fabrication as well as low cost aspects. In this study, a wide variety of FPI sensors are reviewed in terms of fabrication methods, principle of operation and their sensing applications. The chronology of the development of FPI sensors and their implementation in various applications are discussed.

Biometric template protection using watermarking with hidden password encryption

For quite a few years the biometric recognition techniques have been developed. Here, we briefly review some of the known attacks that can be encountered by a biometric system and some corresponding protection techniques. We explicitly focus on threats designed to extract information about the original biometric data of an individual from the stored data as well as the entire authentication system. In order to address security and privacy concerns, we present a biometric authentication scheme that uses two separate biometric features combined by watermark embedding with hidden password encryption to obtain a non-unique identifier of the personage. Furthermore, to present the performance of the authentication system we provide experimental results. The transformed features and templates trek through insecure communication line like the Internet or intranet in the client-server environment. Our projected technique causes security against attacks and eavesdropping because the original biometric will not be exposed anywhere in the authentication system.

Characterization of Mode Coupling in Few-Mode FBG With Selective Mode Excitation

We present the results on fabrication and the characterization of few-mode fiber Bragg gratings (FM-FBGs) inscribed in two mode and four mode step-index fibers. Under the conditions of selective input mode launching, coupling between specific modes of interest can be selectively excited and the self-coupling and cross-coupling properties at the associated resonant wavelengths can be clearly identified and verified by observing the reflected mode intensity profiles. Such FM-FBGs can potentially be used as reflective mode-converters for mode division multiplexed data transmission systems.

Optical Fiber Sensing of Salinity and Liquid Level

This letter reports a fiber optic sensing technology for the detection of salinity and liquid level of a given solution. The operation principle is based on the displacement measurement in a large measuring range by generating a variety of outputs for various sensing objectives. The proposed sensor is investigated analytically and experimentally. The achieved salinity sensitivity is 8.589/%, in addition, the proposed sensor exhibits an excellent liquid level sensitivity of 0.4421/mm in the experiment.

Tilted Fiber Bragg Grating Sensors for Reinforcement Corrosion Measurement in Marine Concrete Structure

In this paper, the tilted fiber Bragg grating is proposed as a corrosion sensor and experimentally demonstrated for measuring and evaluating corrosion of steel rebars in wet conditions. To expedite the corrosion process, the impressed current technique was used to achieve a 28.9% mass loss in the rebar for a total time of 24 h. It is observed that the cladding resonant wavelengths red-shift during the corrosion process and the wavelength shifts are greater for higher order resonances. The proposed technique can be used for monitoring steel corrosion.

Some Numerical Methods for Temperature and Mass Transfer Simulation on the Dehydration of Herbs

Advances in herbs based products preservation and technologies are very significant in order to reduce post-harvest losses. The dynamic mathematical model of concurrent heat and moisture transfer are being established for the simulation of temperature and moisture distributions inside the herbs material during dehydration potential of herbs in a slab-shaped solid. Mathematical modeling presents the exchange of heat and mass transfer between material and drying air. Finite-difference method (FDM) based on Crank-Nicolson was used to discretise a parabolic type partial differential equations (PDE). The key purpose of this study is to illustrate the simulation of tropical herbs’ dehydration through some numerical methods such as Jacobi, Gauss-Seidel and Red-Black Gauss-Seidel. This study focuses on the implementation of sequential algorithms on the simulation. 3D geometric visualization by COMSOL Multiphysics and graphical numerical results of FDM approximation in mass and heat transfer demonstrate the results of this study. The contribution of this study is a flourishing and modified mathematical simulation in representing the concrete process of dehydration in herbs product based industry. Most thermal and moisture models are empirical rather than theoretical. Therefore, the novelty of this paper is the best sources of thermal and moisture data for the commercial tropical herbs dehydration derived from the mathematical model in order to avoid high prototype costs and to improve inaccurate conditions and process parameters with the advancement of dryer technologies. The computational platform is based on Intel®Core™2Quad processors with MATLAB software. The performance analyses of Numerical methods are presented in terms of execution time, computational complexity, number of iterations, errors, accuracy and convergence rate.

Effect of CO 2 Laser Annealing on Stress Applying Parts Contributing Toward Birefringence Modification in Regenerated Grating in Polarization Maintaining Fiber

In this paper, we have demonstrated birefringence modification in regenerated grating in polarization maintaining fiber (RGPMF) by using a CO2 laser annealing technique. After conducting an isothermal annealing procedure followed by a slow cooling process, the birefringence of the RGPMF has been increased. This phenomenon can be explained by the changes in the thermal expansion coefficient and glass transition temperature of the stress applying part at different cooling rates. This process was reversible by reannealing with a subsequent fast cooling process. In our observation, the birefringence exponentially increases with a decreasing cooling rate. The highest and lowest records in the birefringence throughout the annealing process are 4.72 × 10-4 and 3.46 × 10-4, respectively (a difference of 1.26 × 10-4). This finding is useful for the study of the birefringence modification, measurement range, sensitivity, and accuracy of PMF or PMF-related devices.

Performance evaluation of multidimensional parabolic type problems on distributed computing systems

Parabolic Partial Differential Equations (PDE) are well suited to multiprocessor implementation. However, the performance of a parallel program can be damaged by the mismatches between the parallelism available in the application and that available in the architecture. Communication cost, memory requirements, execution time, implementation cost, and others from a problem specific function should be considered to estimate a parallel program. In this paper, we present an optimizing technique called granularity analysis to evaluate the parallel algorithms particularly AGE families without degrading the performances. The resultant granularity analysis scheme is appropriate for developing adaptive parallelism of declarative programming languages on multiprocessors. The results recommend that the proposed method can be used for performance estimation of parallel programs. Red Black Gauss Seidel (GSRB) is selected as the benchmark for the differences numerical methods.

LP 01 –LP 11 Cross-Mode Interference in a Chirped Grating Inscribed in Two-Mode Fiber

We have demonstrated LP01-LP11 cross-mode interference in a single chirped grating (CG) inscribed in a two-mode fiber (TMF). With the aid of a binary phase plate, LP01 mode and LP11 mode can be selectively excited in the CG. By offsetting the position of the phase plate from the center of the input beam, we can simultaneously excite both the spatial modes at different LP01:LP11 intensity ratios in the TMF. The excited modes lead to the formation of different interference patterns in the output spectra. The measured output spectra are found to be in good agreement with the simulation based on a coupled mode theory.

Some parallel numerical methods in solving partial differential equations

This paper will discuss the solution of twodimensional partial differential equations (PDEs) using some parallel numerical methods namely Gauss Seidel and Red Black Gauss Seidel. The selected two-dimensional PDE to solve in this paper are of parabolic and elliptic type. Parallel Virtual Machine (PVM) is used in support of the communication among all microprocessors of Parallel Computing System. PVM is well known as a software system that enables a collection of heterogeneous computers to be used as coherent and flexible concurrent computational resource. The numerical results will be presented graphically and parallel performance measurement by Gauss Seidel and Red Gauss Seidel methods will be evaluated in terms of execution time, speedup, efficiency, effectiveness and temporal performance. Performance evaluations are critical as this paper aimed to fabricate an efficient Two-Dimensional PDE Solver (TDPDES). This new well-organized TDPDES technique will enhance the research and analysis procedure of many engineering and mathematic fields.