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Observation on Responsive OCV Variation od Zinc-Air Cell with Relative Humidity Content
Get PDFZinc/MCM-41/air cell, in its dry form without the electrolyte,demonstrates humidity sensing property. A good linear correlation between the cell's open circuit voltage (OCV) and the relative humidity content is observed. The systempossesses the potential to be developed into a low cost microhumidity sensor. An ultra thin cell of thickness not more than 40 μm has been fabricated and its use as a humiditysensor is substantiated.ABSTRAK: Sel zinc/MCM-41/udara, dalam keadaan kering tanpa elektrolit, menunjukkan sifat pencirian kelembapan. Voltan litar terbuka sel didapati menunjukkan korelasi linear yang baik terhadap kandungan kelembapan relatif. Sistem ini berpotensi untuk dibangunkan menjadi penciri kelembapan mikro yang murah. Sel yang amat nipis dengan ketebalan tidak melebihi 40 μm telah difabrikasi and kegunaannya sebagai penciri kelembapan dibuktikan
Performance Analysis of a Free Space Optics Link with Multiple Transmitters/Receivers
Get PDFABSTRACT:  Multiple transmitters/receivers (TX/RX) are used to improve the quality of Free Space Optics (FSO) communication systems. With the current needs of this technology for longer distance communication, the qualitative analysis of the system has become essential. In this work, the received power level (PR) and bit error rate (BER) are considered to influence the FSO link performance. The relationship between the two parameters are investigated and analysed. Furthermore, the received power for various numbers of TXs and RXs are experimentally measured and compared with the values obtained from theoretical calculations. The first part of the work deals with the theoretical calculation and simulation designs of multiple laser beams based on the commercial FSO used in actual sites. The second part describes the practical work and analysis of the system’s performance.ABSTRAK: Pemancar/penerima berganda (TX/RX) digunakan bagi meningkatkan kualiti sistem komunikasi Ruang Optik Bebas (FSO). Analisis kualitatif ke atas sistemnya adalah penting bagi keperluan semasa teknologi ini untuk jarak jauh. Di dalam kajian ini, aras kuasa penerima (PR) dan kadar ralat bit (BER) telah diambilkira bagi menentukan prestasi rangkaian FSO. Hubungan di antara kedua-dua parameter telah dikaji dan dianalisis. Seterusnya, kuasa penerima untuk pelbagai nombor TXs dan RXs diukur secara eksperimen dan dibandingkan dengan nilai teori yang dikira. Bahagian pertama skop kajian berkaitan dengan pengiraan teori dan rekabentuk simulasi sinaran laser berdasarkan FSO komersial di lapangan. Bahagian kedua kajian adalah kerja lapangan dan analisis prestasi sistem.KEY WORDS: Free Space Optics (FSO) link; Multiple TX/RX FSO; bit error rate (BER); eye diagram
Rational Cubics and Conics Representation: A Practical Approach
Get PDFA rational cubic spline, with one family of shape parameters, has been discussed with the view to its application in Computer Graphics. It incorporates both conic sections and parametric cubic curves as special cases. The parameters (weights), in the description of the spline curve can be used to modify the shape of the curve, locally and globally, at the knot intervals. The rational cubic spline attains parametric smoothness whereas the stitching of the conic segments preserves visually reasonable smoothness at the neighboring knots. The curve scheme is interpolatory and can plot parabolic, hyperbolic, elliptic, and circular splines independently as well as bits and pieces of a rational cubic spline.Key Words: Computer Graphics, Interpolation, Spline, Conic, Rational Cubi
A Comprehensive Computational Design for Microstrip Passive and Active Linear Circuits
No full textIn this paper, a complete program called HHSS2 is introduced which is a user-oriented program capable of designing linear active and passive microstrip circuits such as amplifiers, oscillators, mixers, lowpass filters, and couplers. The substrate parameters and the characteristic impedance of the microstrip lines are given to the program as a common statement. Examples for the design of a 3-GHz high gain amplifier, 2.6-GHz oscillator, ring coupler operated at 3.33 GHz, Lange coupler operated at 3.3 GHz, and maximally-flat lowpass filter operated at 2 GHz with 0.75 GHz cutoff frequency are introduced. Key Words: Computational Microstrip Circuit Design, Microwave Circuits, Computer Aided Design
Catalytic Cracking of Palm Oil Over Zeolite Catalysts: Statistical Approach
Get PDFThe catalytic cracking of palm oil was conducted in a fixed bed micro-reactor over HZSM-5, zeolite ? and ultrastable Y (USY) zeolite catalysts. The objective of the present investigation was to study the effect of cracking reaction variables such as temperature, weight hourly space velocity, catalyst pore size and type of palm oil feed of different molecular weight on the conversion, yield of hydrocarbons in gasoline boiling range and BTX aromatics in the organic liquid product. Statistical Design of Experiment (DOE) with 24 full factorial design was used in experimentation at the first stage. The nonlinear model and Response Surface Methodology (RSM) were utilized in the second stage of experimentation to obtain the optimum values of the variables for maximum yields of hydrocarbons in gasoline boiling range and aromatics. The HZSM-5 showed the best performance amongst the three catalysts tested. At 623 K and WHSV of 1 h-1, the highest experimental yields of gasoline and aromatics were 28.3 wt.% and 27 wt.%, respectively over the HZSM-5 catalyst. For the same catalyst, the statistical model predicted that the optimum yield of gasoline was 28.1 wt.% at WHSV of 1.75 h-1 and 623 K. The predicted optimum yield of gasoline was 25.5 wt.% at 623 K and WHSV of 1 h-1.KEY WORDS: Catalytic Cracking, Palm Oil, Zeolite, Design Of Experiment, Response Surface Methodology
Coagulation-Sedimentation-Extraction Pretreatment Methods for The Removal of Suspended Solids and Residual Oil From Palm Oil Mill Effluent (Pome)
Get PDFSuspended solids and residual oil removal in a liquid are relevant to numerous research areas and industry. The suspended solid cannot be removed completely by plain settling. Large and heavy particles can settle out readily, but smaller and lighter particles settle very slowly or in some cases do not settle at all. Because of this, it requires efficient physical-chemical pretreatment methods. Our current research is to study the pretreatment methods in the removal of suspended solids and residual oil content in POME. Preliminary analysis shows that POME contains 40,000 mg/L suspended solid and 4,000 mg/L oil and grease content that relatively very high compared to the maximum allowable limit by the Malaysian Department of Environment which are only 400 mg/L and 50 mg/L respectively. The methods chosen were coagulation-sedimentation method for suspended solids removal and solvent extraction for residual oil removal. Jar test apparatus was used as the standard procedure for bench-scale testing and alum was used as the coagulant. Parameters studied were alum dosage, mixing time, mixing speed, sedimentation time and pH. For removal of residual oil, six different organic solvents; n-hexane, n-heptane, benzene, petroleum ether, pentane and petroleum benzene were used. For every solvent the effect of solvent ratio, mixing time, mixing speed and pH were analyzed. The results show that the optimum conditions in removal of suspended solid from POME were at pH 4.11, sedimentation time of 100 minutes and 150 rpm mixing speed with 1.5 hr mixing time. N-hexane give the best performance in extracting residual oil from POME with solvent to POME ratio of 6:10. It was estimated about 0.54 grams of oil and grease can be extracted with optimum variables at pH 4, mixing speed of 200 rpm, and 20 minutes mixing time. Key Words: palm oil mill effluent, coagulation, suspended solid, residual oil, solvent extraction
Remarks On Deformation In Snow With Residual Stress And Gravitational Force By Detonation Impact
Get PDFEstimation of strain (deformation) and strain energy at the time of an explosion has been undertaken in the present investigation. A basic concept of explosive pressure which is required for the estimation of strain and strain energy has been drawn from the underwater explosion with suitable modification to the present studies. One of the most significant aspects of the present investigation is to augment the model by accounting it for gravitational force and residual stresses which are of realistic in nature. Studies consist of computational aspect by observing the variation of strain and strain energy with respect to material parameters such as Elastic modulus (E), poisons ratio (?), density (?), and flow parameters such as peak pressure (Pm), sound velocity (Vs), and length of snow slab (L). One of the interesting observation found in the computational aspect is, the deformation is found to decrease as the velocity of sound (Vs) in snow increases which appears to be strange but found factual. The model has been compared with the other existing papers in the literature and found that, the present model yields to better results. ABSTRAK: Anggaran regangan (canggaan) dan tenaga regangan pada masa letupan diambil kira dalam kajian ini. Konsep asas tekanan letupan yang diperlukan untuk anggaran regangan dan tenaga regangan diperolehi daripada letupan bawah air dengan pengubahsuaian yang sesuai dalam kajian terkini. Antara aspek penting dalam kajian ini adalah penambahan model dengan mengambil kira daya graviti dan tegasan sisa yang sebenar. Kajian terdiri daripada aspek pengiraan, dengan memerhatikan variasi regangan dan tenaga regangan terhadap parameter bahan seperti modulus anjal (E), nisbah Poisson’s (?), ketumpatan (?), dan parameter aliran seperti tekanan puncak (Pm), halaju bunyi (Vs), dan panjang papak salji (L). Antara pemerhatian menarik yang ditemui dalam aspek pengiraan ialah, canggaan didapati berkurangan ketika halaju bunyi (Vs) salji bertambah. Walaupun ini nampak asing, tetapi ianya terbukti benar. Model dibandingkan dengan kertas kerja lain dan didapati bahawa, model terkini memberikan keputusan yang lebih tepat.KEYWORDS: avalanche dynamics; fracture mechanics; detonation pressur
Finite Element Simulation of Blanking Process
Get PDFABSTRACT: The blanking process can be simulated by ABAQUS v 6.4 to select punch, die and press and ascertain punch wear and bur height. The experimental and the simulation results agree well with rising punch force up to the point of creation of crack. For a 2mm mild steel sheet, the simulation shows that for the punch force of 240 kN, the crack starts at 30% punch penetration depth and punch force suddenly drops to a value of 70 kN and remains steady till the blanking is complete. Comparing simulation and experimental results for a 3mm mild steel sheet, results agree well in the elastic range with the punch force rising up to point of crack creation. However, a discrepancy appears in punch force which increases with punch penetration. At 32% depth of penetration, the discrepancy is 12 % which increases to 60 % at punch penetration of 42%. Punch force for experimental and simulation results remains about 90kN beyond punch penetration of 62%. Also, increase of the thickness of sheet results in reduced crack height and improved quality of blank.ABSTRAK: Proses pengosongan boleh disimulasikan oleh ABAQUS versi 6.4 untuk memilih tebuk, alat dan tekan; dan menentukan haus tebuk dan ketinggian duri. Keputusan ujikaji dan simulasi adalah serupa dengan kenaikan daya tebuk hingga titik retakan diperolehi. Bagi kepingan keluli ringan 2mm simulasi menunjukkan bahawa untuk tenaga tebukan sebanyak 240 kN, retak bermula pada 30% kedalaman penembusan 30% tebukan dan daya tebuk tiba-tiba jatuh kepada 70 kN dan jumplah ini kekal sehingga proses pengosongan selesai.  Apabila hasil simulasi dan eksperimen dibandingkan, keputusan experimen untuk keluli lembut 3mm, bersetuju dengan baik dalam julat anjal dan daya tebukan meningkat sehingga titik penciptaan retak diperolehi. Walau bagaimanapun percanggahan muncul apabila daya tebukan meningkat dengan daya penembusan. Pada kedalaman penembusan 32% percanggahan adalah 12% dan nilai ini meningkat kepada 60% apabila daya penembusan sebanyak 42%. Daya tebukan yang diukur melalui eksperimen dan simulasi kekal pada kira-kira 90kN melepasi penembusan punch sebanyak 62%. Apabila ketebalan keputusan kunci ditambah, ketinggian retak dikurangkan dan ini meningkatkan kualiti pengosongan.KEYWORDS: simulation; finite element simulation; blanking; computer aided manufacturin
Experimental and Numerical Analysis of Electronics Heat Sink
Get PDFCooling of electronic components continues to attract many research and development activities towards achieving an effective way of cooling. Computational fluid dynamics (CFD) tools may be considered as a cheap substitute for expensive experimental testing methods. In this work the cooling of a simulated electronic board was modeled using FLUENTTM CFD software, and experimental procedures were followed to validate the estimated results, and to understand the factors that would affect the software capability to predict the actual measured values. Results showed good agreement between the simulation and experimental results. The software was found to be capable to predict the exact values at the locations where the temperature values were similar to the board mean temperature. The maximum percentage error was found to be limited to 4.7%, and the capability of the software to estimate the exact measured values was found to be affected by the function of thermal wake generation.
Keywords: CFD, Electronic cooling, Heat sink, Simulatio
Wear Behavior of Woven Roving Aramid / Epoxy Composite under Different Conditions
Get PDFWear behavior studies of aramid woven roving /epoxy composite has been conducted. Sliding the material against smooth steel counter face under dry and lubricated with oil conditions has been investigated. Powder of Silicon carbide has been mixed with the epoxy resin and tested also. The powder was mixed in a volumetric fraction of 10% with the epoxy resin. Four Laminates of six layers were fabricated by hand lay up method. A pin on disc apparatus has been fabricated to conduct the sliding wear tests on specimens of (4 mm 4 mm 12 mm) in size have been cut from the four laminates. The effect of sliding condition including dry, lubricated, dry with additives and lubricated with additives have been studied. Wear rate tests have been conducted at different sliding speeds and loads. Results show that the wear characteristics are influenced by the operating conditions and the construction of the composite material used. It was also found that the wear of aramid /epoxy composite onto the steel counter face were significantly reduced by using lubricant and additives but still took place.Keywords: Wear, Composite materials, Woven roving aramid, Epoxy, Additives, Lubricant