bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of Heat and Mass Transfer in Moist Porous Materials
Authors: Haghi A. K.
Published: January 2013

A mathematical simulatin carried out to study the physical mechanisms of moisture diffusion into hygroscopic fabric during humidity transients. On the basis of a mathematical model developed to describe the coupled heat and moisture transfer in wool fabric, the moistureâ€“sorption mechanisms are investigated for fabrics made from fibers with different degrees of hygroscopicity. Theoretical predictions on the moisture uptake and temperature changes under humidity transients are compared with those measured previously in a sorptionâ€“cell experiment for fabrics made from wool, cotton, acrylic fiber, and polypropylene fiber. It is concluded that hte physical mechanism of moisture diffusion into highly hygroscopic fibers such as wool and cotton can be described by a two stage moisture diffusion process: a fast Fickian diffusion with a concentrationâ€“dependent diffusion coeffecient and slow diffusion with a timeâ€“dependent diffusion coefficient. For weakly hygroscopic fibers such as polypropylene fiber, the moisture sorption process can be described by a single Fickian diffusion with a constant diffusion coefficient. Heat transfer in moist textiles takes place by conduction, infraâ€“red radiation, and distillation. Until the fiber is saturated, the evaporation process is determined mainly by the fiberâ€™s sorption properties. Conductivity increases with water content and also depends on a fiberâ€™s sorption properties.

Key words: Moisturediffusion; hygrospic fabrics; humidity transients
Control of a Robot Arm Using Iterative Learning Algorithm with a Stopping Criterion
Authors: Mailah Musa , Jonathan Chong Wun Shiung
Published: January 2013

Prestasi lasak bagi skema kawalan robot sangat perlu untuk memastikan robot dapat bekerja dengan berkesan seperti yang dikehendaki dalam persekitaran terbatas melibatkan gangguan, perubahan parameter, ketidaktentuan dan kepelbagaian keadaan operasi. Kajian yang dibuat adalah berkaitan dengan satu skema kawalan daya aktif dan algoritma pembelajaran berlelaran (AFCAIL) yang melibatkan satu ciri pembaikan dalam bentuk penggunaan kriteria memberhenti yang sesuai dimuatkan dalam strategi kawalan. Skema tersebut digunapakai terhadap sistem pengolah robotik planar berlengan–dua yang beroperasi secara mendatar. Kriteria memberhenti yang dicadangkan adalah reka bentuk untuk memberhentikan proses pembelajaran berlelaran apabila syarat atau keadaan berkaitan dengan kejituan ketika melakukan tugas serta perolehan matriks inersia anggaran pengolah yang dikehendaki dapat dipenuhi. Dengan cara demikian, robot dikatakan dapat beroperasi dengan baik sebagaimana yang diarahkan. Keberkesanan skema juga dikaji dengan mengambil kira beberapa keadaan bebanan dan operasi.

Kata kunci: Robot; kawalan daya aktif; algoritma pembelajaran berlelaran; kriterion memberhenti

The robust performance of a robot control scheme is vital to ensure that the robot accomplishes its tasks desirably in a constraint environment involving disturbances, parametric changes, uncertainties and varied operating conditions. The study introduces the Active Force Control and Iterative Learning Algorithm (AFCAIL) scheme with an improved feature in the form of a suitably designed stopping criterion incorporated in the control strategy. The scheme is applied to the control of a horiziontally operated robotic two–link planar manipulator. The proposed stopping criterion is specifically designed to halt the iterative learning process when the conditions related to the accuracy of the performed tasks and the acquisition of appropriate estimated inertia matrix of the robot arm are favourably met. In this way, the robot is said to perform desirably and excellently. The effectiveness of the scheme is also investigated by considering a number different loading and operating conditions.

Key words: Robot; active force control; iterative learning algorithm; stopping criterion
Transformasi Terhadap Min bagi Menguji Taburan Terpencong
Authors: Sarmin Nor Haniza , Md Zin Md Hanafiah , Hussin Rasidah
Published: January 2013

Suatu transformasi terhadap min dilakukan menggunakan penganggar pembetulan kepincangan bagi mendapatkan statistik untuk menguji min hipotesis taburan terpencong. Penghasilan statistik ini melibatkan pengubahsuaian pemboleh ubah . Kajian simulasi yang dijalankan terhadap taburan yang terpencong iaitu taburan eksponen, kuasa dua khi dan Weibull ke atas Kebarangkalian Ralat Jenis I menunjukkan bahawa statistik t3 sesuai untuk ujian satu hujung sebelah kiri dan saiz sampel yang kecil (n=5).

Kata kunci: Min; statistik; taburan terpencong; penganggar pembetulan kepincangan; kebarangkalian Ralat Jenis I

A transformation of mean has been done using a bias correction estimator to produce a statistic for mean hypothesis of skewed distributions. The statistic found involves a modification of the variable . A simulation study that has been done on some skewed distributions i.e. esponential, chi-square and Weibull on the Type I Error shows that t3 is suitable for the left-tailed test and a small sample size (n=5).

Key words: Mean; statistic; skewed distribution; bias correction estimator; Type I Error
Degradasi Tirosina Menggunakan Mangkinfoto Berasaskan TiO2
Authors: Ali Rusmidah , Maisoan @ Selamat Siti Salamah
Published: January 2013

Asid amino merupakan bahan asas dalam tisu tumbuhan dan haiwan. Tirosina (Tr) salah satu jenis asid amino yang mengandungi gelang aromatik, telah dipilih sebagai sampel untuk proses degradasi dalam medium akueus. Ini bertujuan melihat kesan penggunaan mangkinfoto dalam sinaran ultralembayung (λ < 400 nm) atau cahaya matahari ke atas molekul tirosina. Kajian telah dijalankan menggunakan sistem cahaya, mangkin serbuk TiO2, hidrogen peroksida, H2O2 dan ion logam. Penambahan ion logam seperti Ni2+, Cu2+, Ag+, Mn2+, Co2+, Fe2+ dan Cd2+ dan agen pengoksidaan, iaitu hidrogen peroksida adalah untuk mendapatkan kaedah yang paling cekap. Keputusan menunjukkan penambahan H2O2 dan ion Fe2+ dan Ni2+ berjaya meningkatkan kecekapan proses degradasifoto tirosina. Ion Ni2+ memberikan keputusan terbaik berbanding ion-ion lain. Ion Cu2+, Ag+, Mn2+ dan Cd2+ merencat proses degradasi. Keputusan juga menunjukkan cahaya matahari adalah setanding dengan cahaya ultralembayung. Kepekatan H2O2 terbaik adalah 5.0 x 10-2M dan semakin banyak TiO2 digunakan semakin baik peratus degradasi tirosina. Oleh itu kaedah optimum untuk proses degradasifoto ialah Tr 2.5 x 10-4 M + TiO2 + H2O25.0 x 10-3 M + Mn+ 1.0 x 10-2 M. Proses degradasifoto dikaji menggunakan spektroskopi ultralembayung-nampak pada julat panjang gelombang 400-200 nm.

Kata kunci: Tirosina; degradasifoto; serbuk TiO; akueus

Amino acid is a basic component in plant or animal tissue. Tyrosine (Tr), an amino acid which contains aromatic ring, was chosen as a sample for a photodegradation process in an aqueous system. The purpose of the experiment is to study the effect of photocatalysis under UV (λ < 400 nm) or sunlight on tyrosine. The experiment was carried out by using UV light, catalyst powder (TiO2), hidrogen peroxide H2O2 and metal ions system. The addition of oxidising agent H2O2 and metal ions such as Ni2+, Cu2+, Ag+, Mn2+, Co2+, Fe2+ and Cd2+ were used in order to achieve the most efficient system. Results showed that the system with added H2O2 and metal ions such as Ni2+ and Fe2+ had successfully enhanced the process of the tyrosine photodegradation. Other metal ions system such as Cu2+, Ag+, Mn2+ and Cd2+ were found to inhibit the degradation process. The results also showed that sunlight was comparable to ultraviolet light. The best H2O2 concentration was 5.0 x 10-2 M and the percentage of tyrosine degradation increased with the addition of more TiO2) by mass. Therefore, the optimum condition for tyrosine photodegradation process was in Tr 2.5 x 10-4 M + TiO2 + H2O2 5.0 x 10-3 M + H2O2 1.0 x 10-2 M. The dissappearance of tyrosine in the photo degradation process was monitored by UV-visible spectroscopy between 400-200 nm.

Key words: Tyrosine; photodegradation; TiO2 powder; akueus
Sliding Mode Control of Active Suspension System
Authors: Md. Sam Yahaya , Osman Johari Halim Shah , Abd. Ghani Mohd. Ruddin
Published: January 2013

Kertas kerja ini mempersembahkan suatu pendekatan baru dalam mengawal sistem gantungan aktif. Pendekatan yang dicadangkan ialah menggunakan skim kawalan mod gelangsar perkadaran-pengkerbedaan. Menggunakan permukaan gelangsar jenis ini, kestabilan asimptotik sistem adalah lebih pasti berbanding dengan jenis permukaan gelangsar konvensional. Skim kawalan yang dicadangkan diaplikasikan penggunaannya dalam mereka bentuk sistem gantungan aktif automotif model kereta suku. Keupayaan sistem kawalan yang direka bentuk akan dibandingkan dengan sistem gantungan pasif yang sedia ada. Kajian dalam bentuk penyelakuan dijalankan untuk membuktikan keberkesanan reka bentuk sistem kawalan berkenaan.

Kata kunci: Kawalan automotif; kawalan mod gelangsar; kawalan tegap; ketakpastian tak terpadan

The purpose of this paper is to present a new approach in controlling an active suspension system. This approach utilized the proportional integral sliding mode control scheme. Using this type of sliding surface, the asymptotic stability of the system during sliding mode is assured compared to the conventional sliding surface. The proposed control scheme is applied in designing an automotive active suspension system for a quarter-car model and its performance is compared with the existing passive suspension system. A simulation study is performed to prove the effectiveness of this control design.

Key words: Automotive control; sliding mode control; robust control; mismatched uncertainties
Skew Detection and Correction of Jawi Images Using Gradient Direction
Authors: Omar Khairuddin , Ramli Abd. Rahman , Mahmod Ramlan , Sulaiman Md. Nasir
Published: January 2013

Kertas kerja ini dikemukakan untuk menjelaskan tentang pembetulan pencongan dan erotan imej jawi. Satu algoritma mudah dan pantas ini menggunakan histogram orientasi cerunan sama seperti yang telah dicadangkan oleh Sun dan Si(1997) terhadap teks Latin telah dicadangkan untuk mengatasi masalah pencongan dan erotan terhadap teks Jawi. Algoritma bermula dengan melaksanakan operasi cerunan imej; diikut oleh penentuan histogram orientasi dan licinkannya menggunakan penapis median. Nilai maksimum histogram dicari untuk mendapatkan sudut pencong; diikuti oleh pembetulan awal dengan menggunakan fungsi polinominal. Sudut dihitung secara analitik; dan akhir sekali imej diputarkan mengikut sudut pencong yang diperoleh. Erotan teks Jawi juga telah menggunakan kaedah yang sama untuk mendapatkan sudut erotan dan kemudian diricih supaya dapat menghasilkan imej yang betul. Hasil daripada algoritma ini menjanjikan keputusan yang baik.

Kata kunci: Histogram orientasi cerunan; topeng penjejak sisi sobel; pencong; erotan; penapis median; dan sudut pencong

This paper discusses an enhancement algorithm of skew and slant orientation of the Jawi images. A simple and quick algorithm that uses a gradient orientation histogram, similar to the one proposed by Sun and Si(1997) for the Latin text is suggested to overcome this skew and slant problem in Jawi text. This algorithm start by carrying out the image gradient operation, followed by determining the orientation histogram and smoothing algorithm with a median filter. The histogram´s maximum value is generated to obtain the skew angle followed by the correcting procedure of the early value obtained by using polynomial function. The angle is calculated analytically and finally converting the image accordingly. The slanted Jawi text uses the same approach as the above to get the slant angle. This image is sheared in order to get the righ image. The outputs of this study show promising and convincing results.

Key words: Gradient orientation histogram; the mask of sobel edge detector; skew; slant; median filter; and skew angle
Fabrication of Fiber Bragg Gratings in High Germania Boron Co-doped Optical Fiber by the Phase Mask Method
Authors: Harun Sulaiman Wadi , Poopalan Prabakaran , Ahmad Harith
Published: January 2013

Kaedah untuk menghasilkan peranti FBG yang mempunyai peratus pantulan yang tinggi diperkenalkan. Peranti FBG telah dicetak dalam gentian optik khas yang mengandungi germanium dan boron yang tinggi. Kandungan germanium ion di dalam gentian optik teras adalah sebanyak mol 20%. Cara yang digunakan ialah cara percetakan topeng fasa dengan menggunakan cahaya ultra ungu ion yang mempunyai panjang gelombang 244 nm sebagai sumber cahaya. Kami telah berjaya menghasilkan FBG yang mempunyai peratus pantulan setinggi 99.9% dan masa yang diambil untuk cetakan adalah kurang daripada 10 minit.

Kata kunci: gentian optik; peranti FBG; laser UV; panjang gelombang Bragg; topeng fasa

A technique to fabricate high reflectivity fiber Bragg gratings (FBGs) with minimal optics is presented. The FBG is written in high germania boron co-doped optical fiber using a phase mask with a 244 nm continuous-wave UV light as the printing source. The mol percentage of germania ion in the fiber core is about 20%. We have successfully fabricated FBGs with reflectivity as high as 99.9% in less than 10 minutes of exposure time.

Key words: Optical fiber; fiber Bragg grating; UV laser; Bragg wavelength; phase mask
Bluetooth Transceivers for Full Duplex Communications in Mobile Robots
Authors: S. H. Choo , M. Amin Shamsudin H , Fisal N. , Yeong C. F. , Abu Bakar J.
Published: January 2013

Projek ini mengeksplotasi penggunaan Teknologi Bluetooth dalam robot mudah alih. Robot mudah alih mempunyai kebolehan untuk bergerak secara automasi menggunakan algoritma yang rumit dan canggih. Algoritma disimpan dalam sebuah komputer sebagai tuan dan juga “server”. Segala bacaan penderia daripada robot mudah alih akan dihantar kepada tuan dan diproses. Kemudian, arahan untuk langkah seterusnya akan dihantar dari “server” kepada robot mudah alih dalam mode komunikasi dua hala dan dupleks penuh. Maka, “otak” utama berada di "server" dan bukannya pada robot mudah alih. Kertas ini akan memfokus pada perantaraan muka antara Bluetooth transceiver dan Handy Board MC68HC11 mikro pengawal pada robot mudah alih. Untuk kes biasa, satu penerima dan penghantar diperlukan untuk setiap alat (server dan client) masing-masing, tetapi dengan Teknologi Bluetooth, hanya dua Bluetooth transceiver diperlukan untuk mencapai perhubungan dupleks penuh. Projek ini telah menghasilkan robot mudah alih dengan kebolehan Bluetooth. Robot tersebut boleh dikawal secara “wirelessly” melalui Bluetooth transceiver.

Kata kunci: Teknologi Bluetooth; dua hala; duplex penuh; automasi; Handy Board

This work explores the implementation of Bluetooth technology in mobile robots. The mobile robot has the capability to move around autonomously using complicated and powerful algorithm. The algorithms are stored in the master as the server. All sensor readings from the mobile robot will be transmitted to the master and processed. Then, command or instruction for further action is transmitted from the server to the mobile robot in a bi-directional full duplex communication mode. Hence, the main “brain” is in the server instead of the mobile robot. This paper will focus on the interfacing between Bluetooth tranceiver and Handy Board MC68HC11 micro-controller of mobile robot. For common case, a receiver and transmitter are needed for each device (robot and control unit), but with Bluetooth technology, only two Bluetooth transceivers are needed to achieve full duplex connection. This project has provided a Bluetooth enabled mobile robot. The mobile robot can be controled wirelessly via Bluetooth transceiver.

Key words: Bluetooth Technology; bi-directional; full duplex; autonomously; Handy Board
Automic Edge Detection in Noisy Fringe Patterns: A Practical Approach
Authors: Ratnam Mani Maran
Published: January 2013

Corak-corak pinggir biasanya dikaji dengan menggunakan tingkap yang ditakrifkan awal kerana kesukaran mencari sempadannya. Hal ini berlaku kerana pinggir-pinggir tersebut biasanya mempunyai keamatan minimum yang serupa dengan keamatan latar belakang dan adalah sukar untuk menentukan di mana sesuatu pinggir bermula dan berakhir. Kehadiran pinggir-pinggir boleh menyebabkan ralat dalam pengesanan sempadan dengan menggunakan kaedah-kaedah pengesanan sempadan yang sedia ada. Kertas kerja ini membentangkan suatu pendekatan praktik ke arah pengesanan automatik sempadan corak pinggir berhingar dengan paras hingar yang berbeza. Teknik tersebut menggunakan operasi-operasi morfologi pengembangan dan penghakisan serta pengesan sempadan binari kejiranan mudah. Nilai ambang yang diperlukan dalam operasi binarisasi ditentukan daripada hubungkait linear antara nilai ambang dengan sisihan piawai hingar Gaussian daripada kajian simulasi. Teknik tersebut kemudian dilaksanakan dengan jayanya pada corak-corak pinggir pada beberapa objek sebenar yang didapati melalui kaedah pengunjuran pinggir. Beberapa kelemahan kaedah tersebut dibincangkan.

Kata kunci: Pengesanan sempadan, corak pinggir

Fringe patterns are usually analyzed using a predefined window due to the difficulty associated with finding their edges. This is because, the fringes usually have minimum intensities similar to that of the background and it is difficult to determine where a fringe starts or ends. The presence of the fringes can therefore lead to errors in detecting the edges of the object when using existing edge detection techniques. This paper presents a practical approach towards the automatic detection of the edges of a noisy fringe pattern having different noise levels. The technique uses the dilation and erosion morphological operators combined with a simple neighborhood binary edge detector. The threshold required for the binarization operation is determined from a linear relationship between the threshold value and the standard deviation of Gaussian noise from a simulation study. The proposed technique has been successfully applied to fringe patterns on real objects obtained using the fringe projection method. Some of the limitations of the technique are discussed.

Key words: Edge detection; fringe patterns
Penyelakuan Reka Bentuk Antena Tampal Segi Tiga Sama Suapan Sisi Beserta Segmen Gangguan Untuk Penerimaan GPS
Authors: Esa Mazlina , Ab. Rashid Muhadzir
Published: January 2013

Struktur mikrojalur adalah antara struktur antena bagi penerimaan isyarat Sistem Penentududukan Global (Global Positioning System, GPS) 1.57542 GHz. Antara fokus penyelidikan masa kini adalah reka bentuk antena bersaiz kecil. Kertas kerja ini membentangkan reka bentuk dan penyelakuan elektromagnet antena tampal mikrojalur suapan tunggal segi tiga sisi sama pada frekuensi kendalian 1.57542 GHz. Teknik suapan yang digunakan adalah suapan sisi mikrojalur. Penyelakuan juga dilakukan bagi struktur dengan segmen gangguan yang melibatkan satu dan dua bukaan pada sisi antena. Prestasi bagi ketiga-tiga struktur ini dibandingkan. Antena dengan bukaan berkendali pada frekuensi lebih rendah, sekaligus mengurangkan saiz struktur. Dua kendalian wujud bila dua bukaan dikenakan terhadap struktur antena. Taburan ketumpatan arus melintangi antena adalah rupa sinus setengah gelombang.

Kata kunci: antena segi tiga sisi sama; penyelakuan; gangguan; bukaan
Reference Pulse CNC Interpolator Based on Enclosing Line for 2D Parametric Curve
Authors: Samad Zahurin , Wan Yusof Wan Azhar
Published: January 2013

Kertas kajian ini mengemukakan algoritma interpolasi CNC bagi lengkok parametrik umum 2D. Interpolasi yang dikemukakan ini menggunakan teknik rujukan-dedenyut ataupun teknik langkah-tambahan. Algoritma ini berasaskan kepada pencarian secara berterusan garisan-lingkungan yang bersilang dengan lengkok parametrik. Setelah garisan-lingkungan dikenalpasti, kawasan jarak-terdekat digunakan untuk memilih titik interpolasi tanpa melaksanakan pengiraan. Simulasi komputer secara real-time menunjukkan bahawa interpolasi yang dikemukakan ini telah meningkatkan halaju maksimum yang dibenarkan dan pada waktu yang sama mengekalkan kejituan yang tinggi.

Kata kunci: interpolator; CNC; rujukan-dedenyut; peralatan mesin

This paper proposes an efficient CNC interpolation algorithm for general 2D parametric curves. The proposed interpolator uses reference-pulse or incremental step technique. The algorithm is based upon finding the successive enclosing-lines that the parametric curve intersects. Once the intersected line is identified, the pre-defined closest distance region is used to select the interpolating point without resorting to calculation. Real-time computer simulations indicate that the proposed algorithm increases maximum allowable velocity while still maintaining high precision.

Key words: interpolators, computerized numerical control (CNC), reference pulse, machine tools
Coarse Resolution Defect Localization Algorithm for an Automated Visual PCB Inspection
Authors: Ibrahim Zuwairie , Al-Attas Syed Abdul Rahman , Aspar Zulfakar
Published: January 2013

Satu daripada asas utama dalam industri pembuatan elektronik ialah pembuatan papan litar bercetak (PCB). Pembuatan PCB pada masa kini perlu melalui proses kikisan. Ini adalah proses satu hala. Proses cetakan yang dilakukan sebelum proses kikisan adalah penyebab utama kepada kecacatan pada PCB. Setelah PCB dikikis, kecacatan itu, jika ada menyebabkan PCB menjadi tidak berguna lagi. Disebabkan oleh keletihan dan keperluan kecepatan, pemeriksaan secara manual tidak efektif dilakukan untuk memeriksa setiap PCB. Oleh itu, pengilang memerlukan sebuah sistem automatik untuk mengesan kecacatan secara masa nyata yang mungkin berlaku semasa proses percetakan. Kecacatan itu akan dikesan dengan menggunakan algoritma pembezaan imej berasaskan wavelet. Seterusnya, kertas kerja ini mencadangkan satu algoritma untuk pemeriksaan visual PCB secara automatik yang berupaya mengesan dan menyari kecacatan pada PCB. Algoritma ini dijalankan pada resolusi kasar pembezaan imej bertujuan untuk mengesan kawasan kecacatan pada resolusi halus imej PCB yang di periksa.

Kata kunci: pengesanan kecacatan; resolusi kasar; wavelets; pemeriksaan PCB

One of the backbones in electronic manufacturing industry is the printed circuit board (PCB) manufacturing. Current practice in PCB manufacturing requires an etching process. This process is an irreversible process. Printing process, which is done before the etching process, caused most of the destructive defects found on the PCB. Once the laminate is etched, the defects, if exist would cause the PCB laminate to become useless. Due to the fatigue and speed requirement, manual inspection is ineffective to inspect every printed laminate. Therefore, manufacturers require an automated system to detect the defects online which may occur during the printing process. The defect is detected by utilizing wavelet-based image difference algorithm. Hence, this paper proposes an algorithm for an automated visual PCB inspection that is able to automatically locate and extract any defect on a PCB laminate. The algorithm works on the coarse resolution differenced image in order to locate the defective area on the fine resolution tested PCB image.

Key words: defect localization; coarse resolution; wavelets; PCB inspection
Effect of Rheological Behaviour of Cellulose Acetate Spinning Solutions on Performance of Reverse Osmosis Hollow Fiber Membranes
Authors: Idris Ani , Ismail A. F. , Gordeyev S. A. , Shilton S. J.
Published: January 2013

Kajian ini bertujuan untuk menyelidik kesan reologi semperitan terhadap membran gentian geronggang osmosis balikan. Ini dilakukan dengan penilaian reologi larutan semperitan selulosa asetat menggunakan sebuah reometer putaran dan sel optik ricih. Sifat hukum kuasa, daya normal dan profil aliran yang terjana memberi penjelasan mengenai fasa balikan dan orientasi molekul. Keputusan reologi ini kemudiannya dihubungkaitkan dengan prestasi membran gentian geronggang osmosis balikan dari segi kadar buangan dan kadar fluks. Keputusan kajian menunjukkan bahawa kadar buangan dan kadar fluks meningkat apabila kadar semperitan larutan meningkat dan ini mungkin disebabkan oleh orientasi molekul.

Kata kunci: reologi semperitan; osmosis balikan; gentian geronggang; orientasi molekul

Rheological assessment of cellulose acetate spinning solution using a rotational rheometer and an optical shear cell in carried out so as to study the cause and effect relationship between membrane preparation, polymer morphology and membrane performance. The power law behaviour, normal force and flow profiles generated provided clues regarding phase inversion and molecular orientation. These rheological results are then related to the separation performance of cellulose acetate reverse osmosis (RO) hollow fibers membranes; both the rejection rate and the flux rate increased with increasing dope extrusion arate, possibly due to the molecular orientation.

Key words: spinning rheology; reverse osmosis; hollow fiber; molecular orientation
Mathematical Modelling and Simulation of Heat Dispersion Due to Fire and Explosion
Authors: Lim Wan Piang , Ahmad Arshad
Published: January 2013

Kebakaran dan letupan adalah antara bahaya yang kerap berlaku dalam operasi loji kimia. Dalam kertas kerja ini, perbincangan ditumpukan terhadap model matematik serakan haba yang berpunca daripada kebakaran dan letupan. Model yang diselaku berasaskan MATLAB ini menggunakan kaedah perbezaan terhingga bagi menyelesaikan masalah yang berkaitan dengan fluks haba dan suhu. Tiga kelas kebakaran telah dipertimbangkan, iaitu kebakaran kolam, kebakaran kilat dan bebola api yang berkait dengan Cecair Didih mengembangkan Wap (BLEVE). Program penyelakuan ini digunakan untuk mengkaji kesan ketiga-tiga bahaya kebakaran tersebut yang diandaikan berlaku di kemudahan storan LPG, Loji Pandu Kejuruteraan Kimia, Universiti Teknologi Malaysia. Keputusan penyelakuan menunjukkan bahawa bebola api menyebabkan berlakunya mala petaka yang paling serius dengan kematian mencapai sehingga jarak 300 meter.

Kata kunci: kebakaran; model pemindahan haba; penyelakuan; pengagihan fluks haba dan suhu.

Fire and explosion are among the commonly occurring major hazards in the operation of chemical plants. In this paper, a mathematical model for heat dispersion in the event of an industrial fire and explosion is presented. The model is simulated numeracally within MATLAB environment to provide both the time and space dependence of the heat flux and temperature using a finite difference method. Three classes of fire were considered. These are pool fire, flash fire and fireball following the event of Boiling Liquid Expanding Vapour (BLEVE). The simulation program that has been developed is employed to study the impact of the three types of fire hazard on a LPG storage facility at the Chemical Engineering Pilot Plant in The Universiti Teknologi Malaysia. Thre results obtained highlights the various hazard condition for all the three events, with fireball imiposing the most severe condition by having safety distance of 300 meters away from the source of release, within which fatalities are expected.

Key words: Fire; heat transfer model; simulation; temperature and heat flux distribution; finite difference
Sains dan Teknologi Asia: Hadiah Asia kepada Dunia
Authors: Mohd. Balwi Mohd Koharuddin
Published: January 2013

Kecemerlangan tamadun asia seringkali ditenggelami oleh kejayaan tamadun barat. Tamadun dunia hari ini sebenarnya terhutang budi kepada kecemerlangan pencapaian tamadun Asia. Malahan tamadun Asialah yang menyediakan asas kepada pencapaian sains dan teknologi dalam pelbagai bidang hingga memungkinkan manusia hari ini mendapat manfaat yang besar. Tamadun Asia ini meliputi tamadun Arab-Islam, Mesir, India, China dan Melayu. Pencapaian tamadun Asia ini meliputi bidang sains dan matematik seperti astronomi, perubatan, kimia dan fizik. Manakala dalam bidang teknologi pula pencapaian tamadun ini telah diakui sangat tinggi dalam bidang pembinaan atau architecture. Selain itu sejarah telah mencatatkan pencapaian tamadun Asia dalam bidang penciptaan seperti penciptaan kertas, kompas, alat-alat pembedahan, sutera dan teknologi seni bina. Pada masa kini Asia juga telah membuktikan keupayaan mereka dalam bidang kejuruteraan elektrik dan mekanikal. Lantaran itu dapatlah dikatakan bahawa sarjana-sarjana hari ini sebenarnya menyambung kecemerlangan sarjana-sarjana Asia dalam melakukan penerokaan, pengubahsuaian dan penciptaan, (Research and Development). Bukanlah sesuatu yang mustahil pada masa akan datang dengan semangat dan kesungguhan yang pernah dimiliki oleh leluhur nenek moyang mereka dahulu, Asia akan bangkit sebagai pusat ketamadunan sains dan teknologi dunia.

Kata kunci: tamadun; asia; pengubahsuaian; penyesuaian; penciptaan dan Research and Development (R & D)
Economic Approach On Externalities And Enviromental Protection Policy
Authors: Ibrahim Mansor
Published: January 2013

Kertas in membincangkan cara untuk menyelesaikan masalah kesan sampingan (externalities)atau pencemaran alam sekitar akibat daripada sesuatu aktibiti ekonomi. Antara pendekatan popular yang digunakan di negara-negara maju ialah Kaedah Pasaran Coase, Kaedah Cukai-Subsidi, Kaedah Piawaian dan Sijil Pencemaran. Secara praktik, Kaedah Piawaian adalah lebih sesuai sebagai polisi pengawalan alam sekitar, jika ianya holeh dilaksanakan dan dikuatkuasakan selwgai saw undang-undang.
Hydrodynamic and Thermal Characteristics of Laminar Slip Flow Over a Horizontal Isothermal Flat Plate
Authors: Lahjomri Jawad , Oubarra Abdelaziz
Published: January 2013

In this paper, hydrodynamic and thermal characteristics of laminar incompressible slip flow over an isothermal semi-infinite flat plate at a relatively low Mach number are considered and revised. The nonsimilar and local similarity solutions of the boundary layer equations with velocity-slip and temperature-jump boundary conditions are obtained numerically for the gaseous slip flow. The numerical calculations are made by assuming no thermal jump for the liquid flow. In addition, the approximate analytical solution of the boundary layer equations for high slip parameter is presented. Results from nonsimilar solution, local similarity approach, and approximate analytical solution are compared. We show that the local similarity approach used by several authors in the last decades produces substantial errors in hydrodynamic and thermal characteristics of the flow. Furthermore, accurate correlations of these characteristics are proposed for gaseous and liquid slip flows. The results of nonsimilar solution show, unlike the previous studies, that the overall skin friction coefficient presents a very slight decrease (indistinguishable) in the interval of the slip flow regime, whereas it decreases significantly as the flow becomes more rarefied. Moreover, with increasing slip condition, the results of overall Nusselt number, for gaseous flow, show that the heat transfer at the plate decreases slightly in the interval of slip flow regime while it increases in the case of liquids flow. This study confirms that for the accurate prediction of characteristics of slip flow, the slip parameter must be treated as a variable rather than a constant in the boundary layer.
Simultaneous Estimation of Principal Thermal Conductivities of an Anisotropic Composite Medium: An Inverse Analysis
Authors: Chanda Samarjeet , Balaji C. , Venkateshan S. P. , Ambirajan Amrit , Ramakrishnan V.
Published: January 2013

This paper reports the results of an experimental study to determine the principal thermal conductivities (kx,ky, and kz) of an anisotropic composite medium using an inverse heat transfer analysis. The direct problem consists of solving the three dimensional heat conduction equation in an orthotropic composite medium with the finite difference method to generate the required temperature distribution for known thermal conductivities. The measurement technique involves dissipating a known heat flux at the central region of a square sample and allowing it to conductively transfer the heat to an aluminium cold plate sink via a square copper ring. At steady state, temperatures at 28 (19 are used for retrievals due to symmetry) discrete locations are logged and used for parameter estimation. The entire measurement process is conducted in a vacuum environment. The inverse heat conduction problem (IHCP) for retrieving the orthotropic thermal conductivity tensor(parameter estimation) is then solved using a two layer feed forward back propagation artificial neural network (ANN) trained using the Levenberg–Marquardt algorithm (LMA), with temperatures as input and thermal conductivity values kx,ky, and kz as the output. The method is first validated against a stainless steel(SS-304) sample of known thermal properties followed by the determination of the orthotropic conductivities of the honeycomb composite material.
Electrokinetic-Driven Flow and Heat Transfer of a Non-Newtonian Fluid in a Circular Microchannel
Authors: Moghadam Ali Jabari
Published: January 2013

An analytical analysis is presented to explore the transport characteristics of electroosmotic flow and associated heat transfer of non-Newtonian power-law fluids in a circular microchannel. The approach selected here is based on the linearized Poisson–Boltzmann distribution equation to get analytical expressions for velocity and temperature profiles, the friction coefficient, and the fully-developed Nusselt number. The key parameters governing the problem include the flow behavior index, the length scale ratio (ratio of half channel diameter to Debye length), and the thermal scale ratio. The results reveal that increasing the length scale ratio tends to increase the friction coefficient. For surface heating, increasing the flow behavior index amplifies the temperature difference between the wall and the fluid, and thus the temperature distribution broadens; while the opposite trend is observed for surface cooling. Depending on the value of the thermal scale ratio, the fully-developed Nusselt number can be either increased or decreased by increasing the flow behavior index and/or the length scale ratio. The effect of flow behavior index on the Nusselt number vanishes as the length scale ratio approaches infinity.
Novel techniques for modifying microtube surfaces with various periodic structures ranging from nano to microscale
Authors: Liu Zhaoqian , Li Jinxing , Lu Bingrui , Chen Yifang , Liu Ran , Huang Gaoshan , Mei Yongfeng
Published: January 2013

Two dimensional (2-D) structured membranes have been well developed and widely studied to find potential applications in broad realms like optics, mechanics, fluidics, and electronics. In this work, the authors have successfully combined the top–down patterning techniques with the roll-up process to convert various structured flat membranes into three dimensional (3-D) microtubes with textured tube-walls. These 3-D textured microtubes may exhibit novel properties different from the original 2-D films and, thus, can be applied in wider research disciplines such as modern material sciences, biology, electrochemistry, etc. Depending on the parameters of the periodic templates including nanoscale porous anodic alumina and microscale imprinted templates in this work, the authors can curve these textured films into 3-D microtubes with structures on the tube-walls by the rolled-up nanotechnique. The specially designed microtubes here have the potential of interesting optical, electrical, and mechanical characteristics as well as possible applications in micro/nanoelectronics, optics, fludics, and bioengineering.
Chemical kinetics of the hydrogen-GePb1 defect interaction at the (100)GexSi1−x/SiO2 interface
Authors: Thoan Nguyen Hoang , Stesmans Andre , Nguyen Anh Phuc Duc , Keunen Koen , Afanas'ev Valery V.
Published: January 2013

A study of the hydrogen passivation/dissociation kinetics of the GePb1 (Ge dangling bond) defect at the (100) GexSi1−x/SiO2 interface shows that the data can be well described by the same generalized simple thermal model as applied to the Si Pb dangling bond defect at the Si/SiO2 interface, enabling inference of the relevant kinetic parameters. It is found that even for optimized treatment, only ∼60% of the GePb1 system can be electrically inactivated through binding to H, which is well below device grade level. This is concluded to be a direct consequence of the existence of excessive spreads in activation energies for GePb1 passivation/reactivation dissociation.
The development of motor synergies in children: Ultrasound and acoustic measurements
Authors: Noiray Aude , Ménard Lucie , Iskarous Khalil
Published: January 2013

The present study focuses on differences in lingual coarticulation between French children and adults. The specific question pursued is whether 4–5 year old children have already acquired a synergy observed in adults in which the tongue back helps the tip in the formation of alveolar consonants. Locus equations, estimated from acoustic and ultrasound imaging data were used to compare coarticulation degree between adults and children and further investigate differences in motor synergy between the front and back parts of the tongue. Results show similar slope and intercept patterns for adults and children in both the acoustic and articulatory domains, with an effect of place of articulation in both groups between alveolar and non-alveolar consonants. These results suggest that 4–5 year old children (1) have learned the motor synergy investigated and (2) have developed a pattern of coarticulatory resistance depending on a consonant place of articulation. Also, results show that acoustic locus equations can be used to gauge the presence of motor synergies in children.
Measuring subjective response to aircraft noise: The effects of survey context
Authors: Kroesen Maarten , Molin Eric J. E. , van Wee Bert
Published: January 2013

In applied research, noise annoyance is often used as indicator of subjective reaction to aircraft noise in residential areas. The present study aims to show that the meaning which respondents attach to the concept of aircraft noise annoyance is partly a function of survey context. To this purpose a survey is conducted among residents living near Schiphol Airport, the largest airport in the Netherlands. In line with the formulated hypotheses it is shown that different sets of preceding questionnaire items influence the response distribution of aircraft noise annoyance as well as the correlational patterns between aircraft noise annoyance and other relevant scales.
Analysis of the time reversal operator for a scatterer undergoing small displacements
Authors: Philippe Franck D. , Prada Claire , Fink Mathias , Garnier Josselin , de Rosny Julien
Published: January 2013

The method of the time reversal operator decomposition is usually employed to detect and characterize static targets using the invariants of the time reversal operator. This paper presents a theoretical and experimental investigation into the impact of small displacements of the target on these invariants. To find these invariants, the time reversal operator is built from the multistatic response matrix and then diagonalized. Two methods of recording the multistatic response matrix while the target is moving are studied: Acquisition either element by element or column by column. It is demonstrated that the target displacement generates new significant eigenvalues. Using a perturbation theory, the analytical expressions of the eigenvalues of the time-reversal operator for both acquisition methods are derived. We show that the distribution of the new eigenvalues strongly depends on these two methods. It is also found that for the column by column acquisition, the second eigenvector is simply linked to the scatterer displacements. At last, the implications on the Maximum Likelihood and Multiple Signal Classification detection are also discussed. The theoretical results are in good agreement with numerical and 3.4 MHz ultrasonic experiments.
The three-channel model of sound localization mechanisms: Interaural time differences
Authors: Dingle Rachel N. , Hall Susan E. , Phillips Dennis P.
Published: January 2013

Previous psychophysical work on sound localization in humans has proposed that a midline channel be added to the current two-channel model of mammalian sound localization mechanisms. Evidence for this third channel has been found in interaural time difference (ITD) studies with low-frequency tones, and interaural level difference (ILD) studies with both high- and low-frequency tones. The latter is interesting because it suggests that, despite the fact that low frequencies do not generate significant ILDs for humans in natural settings, there is a constancy of ILD coding mechanisms across the frequency domain. To complement this finding, the present study sought to determine whether the three-channel model holds for ITDs at high frequencies. In three experiments, a selective adaptation paradigm was used in combination with transposed tones to probe for the existence of three (left, right, and midline) perceptual channels for sound source azimuth. The experiments provided evidence for lateral hemifield ITD channels but little evidence for a midline ITD channel at high frequencies.
Multi-component separation and analysis of bat echolocation calls
Authors: DiCecco John , Gaudette Jason E. , Simmons James A.
Published: January 2013

The vast majority of animal vocalizations contain multiple frequency modulated (FM) components with varying amounts of non-linear modulation and harmonic instability. This is especially true of biosonar sounds where precise time–frequency templates are essential for neural information processing of echoes. Understanding the dynamic waveform design by bats and other echolocating animals may help to improve the efficacy of man-made sonar through biomimetic design. Bats are known to adapt their call structure based on the echolocation task, proximity to nearby objects, and density of acoustic clutter. To interpret the significance of these changes, a method was developed for component separation and analysis of biosonar waveforms. Techniques for imaging in the time–frequency plane are typically limited due to the uncertainty principle and interference cross terms. This problem is addressed by extending the use of the fractional Fourier transform to isolate each non-linear component for separate analysis. Once separated, empirical mode decomposition can be used to further examine each component. The Hilbert transform may then successfully extract detailed time–frequency information from each isolated component. This multi-component analysis method is applied to the sonar signals of four species of bats recorded in-flight by radiotelemetry along with a comparison of other common time–frequency representations.
A three-parameter model for classifying anurans into four genera based on advertisement calls
Authors: Gingras Bruno , Fitch William Tecumseh
Published: January 2013

The vocalizations of anurans are innate in structure and may therefore contain indicators of phylogenetic history. Thus, advertisement calls of species which are more closely related phylogenetically are predicted to be more similar than those of distant species. This hypothesis was evaluated by comparing several widely used machine-learning algorithms. Recordings of advertisement calls from 142 species belonging to four genera were analyzed. A logistic regression model, using mean values for dominant frequency, coefficient of variation of root-mean square energy, and spectral flux, correctly classified advertisement calls with regard to genus with an accuracy above 70%. Similar accuracy rates were obtained using these parameters with a support vector machine model, a K-nearest neighbor algorithm, and a multivariate Gaussian distribution classifier, whereas a Gaussian mixture model performed slightly worse. In contrast, models based on mel-frequency cepstral coefficients did not fare as well. Comparable accuracy levels were obtained on out-of-sample recordings from 52 of the 142 original species. The results suggest that a combination of low-level acoustic attributes is sufficient to discriminate efficiently between the vocalizations of these four genera, thus supporting the initial premise and validating the use of high-throughput algorithms on animal vocalizations to evaluate phylogenetic hypotheses.
Modeling within- and across-channel processes in comodulation masking release
Authors: Dau Torsten , Piechowiak Tobias , Ewert Stephan D.
Published: January 2013

The relative contributions of within-channel and across-channel processes to perceptual comodulation masking release (CMR) were investigated in the framework of an auditory processing model. A generalized version of the computational auditory signal processing and perception model [CASP; Jepsen et al., J. Acoust. Soc. Am. 124, 422–438 (2008)] was used and extended by an across-channel modulation processing stage according to Piechowiak et al. [J. Acoust. Soc. Am. 121, 2111–2126 (2007)]. Five experimental paradigms were considered: CMR with a broadband noise masker as a function of the masker spectrum level; CMR with four widely spaced flanking bands (FBs) varying in overall level; CMR with one FB varying in frequency and level relative to the on-frequency band (OFB); CMR with one FB varying in frequency; and CMR as a function of the number of FBs. The predictions suggest that at least three different mechanisms contribute to overall CMR in the considered conditions: (1) a within-channel process based on changes in the envelope characteristic due to the addition of the signal to the masker; (2) a within-channel process based on nonlinear peripheral processing of the OFB's envelope caused by the FB(s); and (3) an across-channel process that is robust across presentation levels but relatively small (2–5 dB).
Comment on “A theoretical framework for quantitatively characterizing sound field diffusion based on scattering coefficient and absorption coefficient of walls” [J. Acoust. Soc. Am. 128, 1140–1148 (2010)] (L)
Authors: Omoto Akira
Published: January 2013

The relationship between the acoustic scattering characteristics of materials and the degree of diffusion in enclosed acoustic spaces has recently attracted considerable research attention. Hanyu [J. Acoust. Soc. Am. 128(3), 1140–1148 (2010)] introduced a theoretical framework, in which the diffusion time in an enclosure is expressed as a function of a material's average scattering coefficient. In this letter, a modification of this theory is proposed. The decay process of the sound energy through scattering is divided into discrete sub-processes, specifically, a purely scattering process, and alternating scattering and specular reflections. The behavior of each process is examined for different scattering coefficients.
Validation of finite element computations for the quantitative prediction of underwater noise from impact pile driving
Authors: Zampolli Mario , Nijhof Marten J. J. , de Jong Christ A. F. , Ainslie Michael A. , Jansen Erwin H. W. , Quesson Benoit A. J.
Published: January 2013

The acoustic radiation from a pile being driven into the sediment by a sequence of hammer strikes is studied with a linear, axisymmetric, structural acoustic frequency domain finite element model. Each hammer strike results in an impulsive sound that is emitted from the pile and then propagated in the shallow water waveguide. Measurements from accelerometers mounted on the head of a test pile and from hydrophones deployed in the water are used to validate the model results. Transfer functions between the force input at the top of the anvil and field quantities, such as acceleration components in the structure or pressure in the fluid, are computed with the model. These transfer functions are validated using accelerometer or hydrophone measurements to infer the structural forcing. A modeled hammer forcing pulse is used in the successive step to produce quantitative predictions of sound exposure at the hydrophones. The comparison between the model and the measurements shows that, although several simplifying assumptions were made, useful predictions of noise levels based on linear structural acoustic models are possible. In the final part of the paper, the model is used to characterize the pile as an acoustic radiator by analyzing the flow of acoustic energy.