IIUM Engineering Journal
Not a member yet
783 research outputs found
Sort by
Review of Wavelet Theory and Its Application Toimage Data Compression
Get PDFThe fast development of computing multimedia has led to the demand of using digital images. The manipulation, storage and transmission of these images in their raw form is very expensive, it significantly slows the transmission and makes storage costly. In this paper, a brief review of wavelet transform theory is given using filters as examples to show the related multiresolution analysis. Advantages over Fourier transform is investigated and several results are derived. The pyramid algorithm is also presented and some features of wavelets in image data compression are given. A modified version of Lind Boze and Gray (LBG) algorithm using Partial Search Partial Distortion (PSPD) is presented for coding the wavelet coefficients to speed up the codebook generation and the search required for nearest neighbour codevector of input image. The proposed scheme can save 70 - 80 % of the Vector Quantization (VQ) encoding time as compared to fully search VQ and reduced arithmetic complexity with less sacrificing performance.Key Words: Image compression, Wavelets transform, Vector qQuantizatio
On The Settling And Response Times Of Underdamped Second-Order Systems
Get PDFThe normalized settling time (ts /?) values of oscillatory 2nd-order systems, when subjected to a step-change forcing function (SCFF), depend on the sensitivity of the measuring instrument employed to indicate the response (± x%). An attempt is made to mathematically relate ts /? to ± x% utilizing the exact, and a simplified, expression for the lower boundary of the decay envelope (LBDE). The two obtained relationships were tested against the actual ts /? values for a settling band range of ±1% ? ±x% ? ±6%, covering a damping coefficient range of 0.1 ? ? ? 0.65. Although the relationships are not exact, their general trend is a marginal overestimation of ts /?. The relationship based on the simplified LBDE was chosen for being simpler and slightly more accurate of the two. This led to a suggested distinction between ts /? and the normalized response time (tR /?) with the latter assigned the value 5/ ? . The ratio ts /tR can thus be readily established for any ± x% value.
ABSTRAK: Masa enapan ternormal (ts/?) nilai ayunan system terbit kedua, apabila fungsi memaksa ubah berperingkat (step-change forcing function (SCFF)) dijalankan ke atasnya, bergantung kepada kepekaan alat pengukur yang digunakan untuk mengukur respons (± x%). Satu percubaan dijalankan secara matematik untuk mengaitkan ts/? to ± x% dengan mempergunakan ekspresi yang tepat dan mudah, pada sempadan bawah sampul reputan (lower boundary of the decay envelope (LBDE)). Dua hubungan yang diperolehi dikaji terhadap nilai ts/t sebenar untuk julat jalur enapan ±1% ? ±x% ? ±6%, melingkungi julat pekali redaman 0.1 ? ? ? 0.65. Walaupun hubungannya tidak tepat, trend umum merupakan penganggaran marginal ts/?. Hubungan berdasarkan LBDE adalah berdasarkan LBDE yang telah dipermudahkan, ia dipilih kerana ianya senang dan agak tepat antara keduanya. Ini mendorong kepada perbezaan yang disarankan antara ts/? dan waktu respons ternormal (tR/?), dengan nilai 5/ ? yang ditetapkan kemudiannya
NUMERICAL SIMULATIONS OF FLOW BEHAVIOR IN DRIVEN CAVITY AT HIGH REYNOLDS NUMBERS
Get PDFIn recent years, due to rapidly increasing computational power, computational methods have become the essential tools to conduct researches in various engineering fields. In parallel to the development of ultra high speed digital computers, computational fluid dynamics (CFD) has become the new third approach apart from theory and experiment in the philosophical study and development of fluid dynamics. Lattice Boltzmann method (LBM) is an alternative method to conventional CFD. LBM is relatively new approach that uses simple microscopic models to simulate complicated microscopic behavior of transport phenomena. In this paper, fluid flow behaviors of steady incompressible flow inside lid driven square cavity are studied. Numerical calculations are conducted for different Reynolds numbers by using Lattice Boltzmann scheme. The objective of the paper is to demonstrate the capability of this lattice Boltzmann scheme for engineering applications particularly in fluid transport phenomena. Keywords-component; lattice Boltzmann method, lid driven cavity, computational fluid dynamics
Theoretical Modeling and Simulation of Phase-Locked Loop (PLL) for Clock Data Recovery (CDR)
Get PDFModern communication and computer systems require rapid (Gbps), efficient and large bandwidth data transfers. Agressive scaling of digital integrated systems allow buses and communication controller circuits to be integrated with the microprocessor on the same chip. The Peripheral Component Interconnect Express (PCIe) protocol handles all communcation between the central processing unit (CPU) and hardware devices. PCIe buses require efficient clock data recovery circuits (CDR) to recover clock signals embedded in data during transmission. This paper describes the theoretical modeling and simulation of a phase-locked loop (PLL) used in a CDR circuit. A simple PLL architecture for a 5 GHz CDR circuit is proposed and elaborated in this work. Simulations were carried out using a Hardware Description Language, Verilog-AMS. The effect of jitter on the proposed design is also simulated and evaluated in this work. It was found that the proposed design is robust against both input and VCO jitter.ABSTRAK: Sistem komunikasi dan komputer moden memerlukan pemindahan data yang cekap (Gbps), dan bandwidth yang besar. Pengecilan agresif menggunakan teknik sistem digital bersepadu membenarkan bas dan litar pengawal komunikasi disatukan dengan mikroprocessor dalam cip yang sama. Protokol persisian komponen sambung tara ekspres (PCIe) mengendalikan semua komunikasi antara unit pemprosesan pusat (CPU) dan peranti perkakasan. Bas PCIe memerlukan litar jam pemulihan data (CDR) yang cekap untuk mendapatkan kembali isyarat jam yang tertanam dalam data semasa transmisi. Karya ini menerangkan teori pemodelan dan simulasi gelung fasa terkunci (PLL) untuk CDR. Rekabentuk 5 GHz PLL yang mudah telah dicadangkan dalm kertas kerja ini. Simulasi telah dijalankan menggunakan perisian verilog-AMS. Simulasi mengunnakan kesan ketar dalam reka bentuk yang dicadangkan telah dinilai. Reka bentuk yang dicadangkan terbukti teguh mengatasi ganguan ketar di input dan VCO.KEY WORDS: phase-locked loop (PLL); jitter; phase detector; low-pass filter; voltage-controlled oscillato
Investigation of Residual Stresses and Distortion in Welded Pipe-Flange Joint of Different Classes
Get PDFABSTRACT: Pipe and flange joints are commonly used in petrochemical, nuclear and process industries. Commonly, welding is used to make these joints which produces residual stresses and distortions. These stresses have detrimental effects on the structural integrity and service performance of the welded pipe joints. The objective of this study is to investigate the residual stresses and distortions during Gas Metal Arc Welding of pipe of schedule 40, nominal diameter 200 mm with different ANSI flanges of class numbers 150, 300, 600, 900, 1500, and 2500. Welding parameters including: voltage, current and heat as inputs were selected based on the literature available. The behaviour of the flanges of different classes is also discussed. In addition, the finite element methodology presented, in this paper, can be helpful for developing welding procedures for a range of pipe flange welded joint sizes in order to control the residual stresses and deformations. This will lead to optimised performance during bolt up and operating conditions.ABSTRAK: Paip dan sambungan flan biasanya digunakan dalam industri petrokimia, nuklear dan proses. Kimpalan menghasilkan tegasan sisa dan herotan, yang memberikan kesan yang merbahaya ke atas integriti struktur dan prestasi servis sambungan kimpalan paip. Objektif kajian ini adalah untuk mengkaji tegasan sisa dan herotan ketika kimpalan arka logam gas paip berjadual 40, diameter nominal 200mm dengan flan ANSI yang berbeza kelas # 150, 300, 600, 900, 1500, dan 2500. Parameter kimpalan termasuklah; voltan, arus dan haba input yang dipilih berdasarkan literatur sediada. Kelakuan flan yang berbeza kelas telah dibincangkan. Kaedah elemen finit yang dibentangkan adalah berguna dalam membangunkan prosedur kimpalan bagi julat saiz kimpalan flan paip unutk mengawal tegasan sisa dan canggaan i.e. bagi mengoptimakan prestasi ketika bolt up dan sedang beroperasi.                                                                 KEYWORDS: finite element; residual stresses; distortion; welding; pipe-flange joint; different classe
High Speed Submarine Optical Fiber Communication System:Pressure and Temperature Effects
Get PDFIn the present paper, the performance of high speed submarine optical fiber cable systems is investigated, taking into account both the pressure and the temperature effects. Both the pressure and the temperature are depth-dependent variables, while both the spectral losses and the dispersion effects are temperature as well as wavelength dependent variables. Two important cases with real fibers are processed: a case with dispersion cancellation and a case without dispersion cancellation. It is found that the ocean pressure (due to the depth) shifts the dispersion-free wavelength towards the third communication window. In general, as the depth increases the maximum transmitted bit rate increases in the range of interest. The system capacity as well as the spectral losses, and the dispersion effects are parametrically investigated over wide-range ranges of the set of affecting parameters {wavelength, ocean depth (and consequently the ocean pressure and temperature), and the chemical structure}. Key Words: Submarine Optical Fiber, Undersea Optical Communication, Pressure and Temperature Effects, Transoceanic Optical Communication
Application of Ion Beam Processing Technology in Production of Catalysts
Get PDFIn this paper, the applicability of Ion Beam Processing Technology for making catalysts has been inves-tigated. Ceramic substrates of different shapes and metal fibre tablets were implanted by platinum ions and tested in nitrogen oxides (NOx) and carbon monoxide (CO) conversion reactions. Effectiveness of the implanted catalysts was compared to that of the commercially produced platinum catalysts made by impregnation. Platinum-implanted catalyst having fifteen times less platinum content showed the same CO conversion efficiency as the commercially pro-duced catalyst. It was revealed that the effectiveness of the platinum-implanted catalyst has complex dependence on the process parameters and the optimum can be achieved by varying the ions energy and the duration of implantation. Investigation of the pore structure showed that ion implantation did not decrease the specific surface area of the catalyst.Key Words: Catalyst, Ion Implantation, Noble metals
Modeling Of A Reactive Distillation Column: Methyl Tertiary Butyl Ether (Mtbe) Simulation Studies
Get PDFA process simulation stage-wise reactive distillation column model formulated from equilibrium stage theory was developed. The algorithm for solving mathematical model represented by sets of differential-algebraic equations was based on relaxation method. Numerical integration scheme based on backward differentiation formula was selected for solving the stiffness of differential-algebraic equations. Simulations were performed on a personal computer (PC Pentium processor) through a developed computer program using FORTRAN90 programming language. The proposed model was validated by comparing the simulated results with the published simulation results and with the pilot plant data from the literature. The model was capable of predicting high isobutene conversion for heterogeneous system, as desirable in industrial MTBE production process. The comparisons on temperature profiles, liquid composition profile and operating conditions of reactive distillation column also showed promising results. Therefore the proposed model can be used as a tool for the development and simulation of reactive distillation column.Keywords: Modeling, simulation, reactive distillation, relaxation method, equilibrium stage, heterogeneous, MTB
Antnet: A Robust Routing Algorithm for Data Networks
Get PDFSuccessful implementation and operation of a network largely depends on the routing algorithm in use. To date, several routing algorithms are in use but the problem with these algorithms is that they are either not adaptive or not robust enough, thus limiting the proper use of bandwidth. AntNet is an innovative algorithm that may be used for data networks. It is a combination of both static and dynamic routing algorithms. In this algorithm, a group of mobile agents (compared to real ants) form paths between source and destination nodes. They explore the network continuously and exchange obtained information indirectly, in order to update the routing tables at different nodes. Our version of AntNet (hereinafter referred to as AntNet2.0) has been improved to overcome the problems with other algorithms. This paper compares the performance of AntNet2.0 against two other commercially popular algorithms, viz. link state routing algorithm and distant vector routing algorithm. The performance matrix used to compare the algorithms is based on average throughput, packet loss, packet drop and end-to-end delay. Convergence time for this algorithm on a nation-wide telecommunications network will also be discussed. Conclusions and areas of further work will also be presented in lucid manner, so that it may be transformed into real practice in the future.Key Words: mobile agents, swarm intelligence, networks and constant bit rat
Biotransformation of Domestic Wastewater Treatment Plant Sludge by Two-Stage Integrated Processes -Lsb & Ssb
Get PDFThe study of biotransformation of domestic wastewater treatment plant (DWTP) sludge was conducted in laboratory-scale by two-stage integrated process i.e. liquid state bioconversion (LSB) and solid state bioconversion (SSB) processes. The liquid wastewater sludge [4% w/w of total suspended solids (TSS)] was treated by mixed filamentous fungi Penicillium corylophilum and Aspergillus niger, isolated, screened and mixed cultured in terms of their higher biodegradation potential to wastewater sludge. The biosolids was increased to about 10% w/w. Conversely, the soluble [i.e. Total dissolve solid (TDS)] and insoluble substances (TSS) in treated supernatant were decreased effectively in the LSB process. In the developed LSB process, 93.8 g kg-1of biosolids were enriched with fungal biomass protein and nutrients (NPK), and 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of chemical oxygen demand (COD) in treated sludge supernatant were removed after 8 days of treatment. Specific resistance to filtration (1.39x1012 m/kg) was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation. The treated biosolids in DWTP sludge was considered as pretreated resource materials for composting and converted into compost by SSB process. The SSB process was evaluated for composting by monitoring the microbial growth and its subsequent roles in biodegradation in composting bin (CB). The process was conducted using two mixed fungal cultures, Trichoderma harzianum with Phanerochaete chrysosporium 2094 and (T/P) and T. harzianum and Mucor hiemalis (T/M); and two bulking materials, sawdust (SD) and rice straw (RS). The most encouraging results of microbial growth and subsequent solid state bioconversion were exhibited in the RS than the SD. Significant decrease of the C/N ratio and germination index (GI) were attained as well as the higher value of glucosamine was exhibited in compost; which clearly implied that the increased bioconversion occurred in the treated process. Comparatively, superior composts were produced by T/P at 50-60 days of SSB. Significantly lower heavy metals (Pb, Cd, Cr, Ni, Cu and Zn) were recorded in chemical analysis of the end products (composts) after SSB, in comparison to the USA’s recognized limits for application in municipal solid waste (MSW).Keywords: Liquid state bioconversion, solid state bioconversion, domestic wastewater sludge, filamentous fungi, biosolids and compost