bluuebunny/crossref_metadata_2025 huggingface dataset:
Fuzzy Sets in the Social Sciences: An Overview of Related Researches
Authors: Abdullah Mohd. Lazim , Wong Abdullah Wan Salihin , Md. Tap Abu Osman
Published: January 2013

Pemodelan matematik yang berasaskan set kabur selalunya dikaitkan dengan pengajian dalam bidang kejuruteraan dan sains komputer. Oleh kerana fenomena kekaburan dalam kehidupan dikaitkan dengan kemanusiaan, maka kertas kerja ini membincangkan penggunaan set kabur dalam sains sosial. Satu kajian berkaitan dibentangkan di mana contoh menggunakan model kabur untuk mengukur data kabur daripada soal selidik dikemukakan. Kertas kerja ini turut membincangkan soal selidik yang banyak digunakan dalam penyelidikan sains sosial serta unsur kekaburan yang terlibat. Atribut dan label bagi pembolehubah linguistik daripada soal selidik yang tidak jelas diubah kepada yang ada nilai matematik. Model kabur ini menyediakan pembaikan dalam analisis data serta memberi kesimpulan yang lebih tepat. Kertas kerja ini memberi satu kefahaman baru tentang penggunaan meluas dan sumbangan set kabur dalam sains sosial.

Kata kunci: Set kabur, sains sosial, model kabur, pembolehubah linguistik, konjoin kabur

A mathematical modelling based on the fuzzy sets theory is synonymous with the fields of engineering and computer science. Since the phenomena of fuzziness in the real world is also closely related with human beings, this paper discusses the application of fuzzy sets in social sciences. An overview of related research is presented, which focuses on an example of social research using a fuzzy model to measure the fuzzy data from a questionnaire. This paper also discusses the questionnaire that is used to collect data by many researchers in social sciences and the elements of fuzziness in it. The vague attributes and labels of a linguistic variable from the questionnaire would be transformed into standard mathematical values. This fuzzy model offers a substantial improvement in data analyses and gives more accurate conclusions. In short, this paper gives a new insight of the vast contribution of fuzzy sets in social sciences.

Key words: Fuzzy sets, social sciences, fuzzy model, linguistic variables, fuzzy conjoint
Perkembangan, Pembangunan dan Penerimaan E–Pembelajaran di Institusi Pengajian Tinggi Malaysia
Authors: Mohd. Balwi Mohd. Koharuddin , Sanapi Rozita
Published: January 2013

Kertas ini mendedahkan perkembangan, pembangunan dan penerimaan pelaksanaan program e–pembelajaran di pelbagai universiti di Malaysia. Agenda Teknologi Maklumat Kebangsaan (NITA) telah dilancarkan oleh bekas Perdana Menteri Malaysia, Tun Dr. Mahathir Mohamad yang juga merupakan pengerusi Majlis Teknologi Maklumat Kebangsaan (NITC). Di antara inisiatif NITA ialah pembangunan Koridor Raya Multimedia (MSC). NITC mempunyai Agenda Strategik Teras yang antara lain merupakan objektif terpenting bagi memastikan penglibatan masyarakat secara menyeluruh dalam jaringan global seperti e–ekonomi, e–perhidmatan awam, e–komuniti, e–pembelajaran dan e–kedaulatan. Kementerian Pendidikan Malaysia dan sektor swasta telah diberikan tanggungjawab untuk merealisasikan Agenda E–Pembelajaran Kebangsaan. Lantaran itu beberapa Universiti di Malaysia telah memulakan inisiatif program e–pembelajaran untuk pelajar–pelajar mereka. Melalui program e–pembelajaran ini, pelajar didedahkan dengan bentuk pembelajaran yang baru kerana bahan pembelajaran dapat dicapai di mana–mana dan pada bila–bila masa.

Kata kunci: e-pembelajaran, universiti-universiti Malaysia, Agenda Teknologi Maklumat Kebangsaan, Koridor Raya Multimedia (MSC), e-ekonomi, e-perkhidmatan awam, e-komuniti, e-kedaulatan, alat pembelajaran

This paper attempts to reveal the progress, development, and acceptance of the implimentation of e–learning programme by various Malaysian Universities. The National Information Technology Agenda (NITA) was launched in December 1996 by the National Information Technology Council (NITC), chaired by the former Prime Minister, Tun Dr Mahathir Mohamed. Amongst the initiative of the NITC is the establishment of the Multimedia Super Corridor (MSC). NITC has also launched its Core Strategic Agenda with its prime objective to enhance the people’s involvement and use of global networks such as e–economy, e–public services, e–community, e–learning and e–sovereignty. The Malaysian Ministry of Education and the private sector have been given the responsibility to realise the National E–Learning Agenda. A few Malaysian universities have started e–learning initiative programmes for their students. Through e–learning, teaching–learning materials can be accessed by students from anywhere, at anytime.

Key words: e-learning; Malaysia universities; National Information Technology Agenda; the Multimedia Super Corridor (MSC); e-economy; e-public services; e-community; e-sovereignty; learning tool
A New Prediction Methodology For Dynamic Contact Pressure Distribution In A Disc Brake
Authors: Abu Bakar Abd Rahim , Abdul Hamid Mohd Kameil , Ouyang Huajiang
Published: January 2013

Taburan tekanan sentuhan dinamik masih lagi tidak dapat diukur secara uji kaji. Ini menjadikan kaedah berangka melalui analisis unsur terhingga merupakan pilihan alternatif yang terbaik bagi tujuan tersebut. Namun begitu, model unsur terhingga yang dibina perlu terlebih dahulu diujisahkan agar hasil ramalan yang diperolehi memuaskan dan realistik. Kertas kerja ini mencadangkan dan menjalankan pengujisahan ke atas model secara tiga peringkat iaitu mengujisahkan aspek kelakuan dinamik pada setiap komponen brek cakera dan juga pemasangan selain daripada pengujisahan tekanan sentuhan statik dengan keputusan daripada pengujian. Model 3-dimensi telah dibina berdasarkan komponen sebenar. Permukaan topografi bahan geseran diambilkira dan dimodelkan dalam model unsur terhingga. Hasil analisis mencatatkan keputusan yang memberangsangkan di mana model menunjukkan persamaan dengan keputusan uji kaji bagi kelakukan dinamik dan juga tekanan sentuhan statik. Setelah model diujisahkan, analisis tekanan sentuhan dinamik dilakukan.

Kata kunci: brek cakera, tekanan sentuhan dinamik, topografi permukaan, ujian sentuhan, analisis modal, unsur terhingga

The dynamic contact pressure distribution in a disc brake system remains impossible to measure through experimental methods. This makes numerical analysis using the finite element method an indispensable alternative tool to its prediction. However, the finite element model must first be validated through appropriate analyses so that realistic predicted results can be obtained. This paper proposes and carries out a three-stage validation methodology: validating the dynamic aspect of each brake component and the brake assembly using modal testing data and the contact aspect using the experimental results of static contact pressure. A detailed 3-dimensional finite element model of an actual disc brake was developed. Brake pad surface topography is also taken into consideration. Good agreement is achieved between predicted and experimental results both in modal analysis and static contact pressure distributions. Once a validated model was obtained, contact analysis for dynamic condition of the disc brake is performed.

Key words: disc brake, dynamic contact pressure, surface topography, contact tests, modal analysis, finite element
Mixed Convection Boundary Layer Flow Over A Vertical Permeable Plate In A Porous Medium: Opposing Flow Case
Authors: Nazar Roslinda , Pop Ioan
Published: January 2013

Kajian aliran menentang bagi aliran lapisan sempadan olakan campuran mantap terhadap permukaan menegak telap dalam medium berliang dengan syarat–syarat permukaan terma yang seragam, iaitu apabila kedua–dua suhu dan fluks haba dinding adalah malar, dipertimbangkan. Nilai nombor Rayleigh bagi medium berliang diandaikan besar supaya penghampiran lapisan sempadan boleh dipertimbangkan. Dengan andaian ini, didapati masalah ini bergantung pada parameter pemindahan jisim dan parameter olakan campuran. Seterusnya, ditunjukkan bahawa persamaan–persamaan menakluk boleh diturunkan kepada bentuk keserupaan, iaitu bentuk persamaan pembezaan biasa. Persamaan–persamaan tersebut diselesaikan secara berangka menggunakan suatu skim beza terhingga tersirat yang efisien, dikenali sebagai kaedah kotak Keller. Keputusan berangka bagi geseran kulit terturun dan suhu dinding tanpa matra dibincangkan bagi nilai–nilai parameter yang dipertimbangkan. Penemuan penting dalam masalah ini adalah terdapatnya penyelesaian dual bagi persamaan menakluk lapisan sempadan dan pemisahan lapisan sempadan berlaku untuk beberapa kes.

Kata kunci: Olakan campuran, lapisan sempadan, plat telap, medium berliang, aliran menentang

The opposing flow case of steady mixed convection boundary layer flow over a vertical permeable surface in a porous medium with uniform thermal wall conditions, i.e. when both the wall temperature and the wall heat flux are constants, is considered. The Rayleigh number for the porous medium is assumed to be large so that the boundary layer approximation can be considered. Under these assumptions, it is found that the problem depends both on the mass transfer parameters and the mixed convection parameters. It is shown that the governing equations can be reduced to a similarity form, i.e. to ordinary differential equations. These equations are solved numerically using a very efficient implicit finite difference scheme known as the Keller–box method. Numerical results for the reduced skin friction and non–dimensional wall temperature are presented and discussed in detail for various values of the parameters of interest. An important finding of this problem is that there are dual solutions of the governing boundary layer equations and the separation of boundary layer occurs for certain cases.

Key words: Mixed convection, boundary layer, permeable plate, porous medium, opposing flow
Weld Extraction From Digitised Radiographs Using Graphical Analysis Of Weld Intensity Profiles
Authors: Leong Soo Say , Samad Zahurin , Ratnam Mani Maran , Khalid Mohd Ashhar
Published: January 2013

Kertas kerja ini membentangkan suatu kaedah yang berkesan untuk menyari kimpalan secara automatik daripada radiograf yang telah didigitkan. Suatu algoritma untuk menentukan kedudukan dan menyari kimpalan daripada profil keamatan melintasi imej dengan menggunakan kaedah analisis grafik yang mudah telah dibangunkan. Algorithma tersebut telah diaplikasi untuk menyari kimpalan daripada 45 imej radiograf yang didigitkan. Kaedah segmentasi kimpalan yang dicadangkan didapati beroperasi dengan baik pada radiograf yang mempunyai taburan keamatan melintasi kawasan kimpalan.

Kata kunci: Ujian takmusnah, radiografi kimpalan, penyarian kimpalan.
Optical Waveguide Modelling Based On Scalar Finite Difference Scheme
Authors: Mohd Kassim Norazan , Mohammad Abu Bakar , Ibrahim Mohd Haniff
Published: January 2013

Pemodelan pandu gelombang optik telah dilakukan dengan kaedah berangka berasaskan pembezaan skalar terhingga menggunakan peraturcaraan MATLAB(r). Perbandingan dengan kaedah lain telah dijalankan bagi menilai kebolehupayaannya dalam pemodelan tersebut. Keputusan perbandingan menunjukkan ciri-ciri kualitatif yang sama antara kaedah tersebut. Prestasi kaedah ini juga telah dinilai berdasarkan kepada kerumitan pengiraan, saiz jaring dan kesan faktor cepatan. Kerumitan pengiraan boleh dikurangkan dengan menambahkan saiz jaring tetapi ini akan menambahkan ralat pengiraan. Masalah ini boleh diatasi dengan memperkenalkan faktor cepatan iaitu parameter SOR. Telah dibuktikan bahawa julat SOR di antara 1.3 dan 1.7 akan menghasilkan masa pengiraan yang lebih singkat dan keputusan simulasi yang lebih konsisten.

Kata kunci: Gelombang optik pandu, pemodelan pandu gelombang

A numerical method based on scalar finite difference scheme is adopted and programmed on MATLAB(r) platform for optical waveguide modeling purpose. Comparisons with other established methods in terms of normalized propagation constant are included to verify its applicability. The comparison results obtained are proven to have the same qualitative behaviour. Furthermore, the performances are evaluated in terms of computation complexity, mesh size and effect of acceleration factor. Computation complexity can be reduced by increasing the mesh size which will then produce more error. The problem can be rectified by introducing the acceleration factor, Successive Over Relaxation (SOR) parameter. It shows that SOR range between 1.3 and 1.7 can give shorter computation time, while producing constant value of simulation results.

Key words: Optical waveguide, waveguide modelling, finite difference technique, successive over relaxation
PC Controlled Function Generator Using Direct Digital Synthesis (DDS) Technology For Electrical Capacitance Tomography
Authors: Abdul Rahim Ruzairi , Teo Chin Heng , Sulaiman S. , Abdul Manaf M. S.
Published: January 2013

Penjana frekuensi telah digunakan secara meluas dalam pelbagai jenis ujikaji. Ia digunakan untuk menjana pelbagai bentuk gelombang (gelombang sin, gelombang segiempat dll) pada frekuensi dan lebar jalur tertentu. Satu daripada aplikasinya ialah dalam Proses Tomografi jenis Kapasitif (ECT) di mana ia digunakan untuk menyalurkan maklumat mengenai keadaan aliran. Kertas kerja ini menjelaskan bagaimana mereka bentuk sebuah Penjana Fungsi yang Dikawal oleh Komputer Peribadi yang ekonomi untuk kegunaan ujikaji makmal. Rekaan ini berbeza dengan penjana fungsi manual kerana ia hendaklah dikawal secara digital. Dalam kes ini, teknologi DDS (Direct Digital Synthesis) digunakan kerana cip DDS adalah digital secara semulajadinya. Analisis telah dibuat untuk memeriksa ketepatan keluaran fungsi dari segi frekuensi dan amplitudnya.

Kata kunci: Penjana frekuensi, sintesis secara terus (DDS)

A function generator is widely used for experimental work and testing to generate various types of waveform (sine, square, triangle, etc) with a particular frequency bandwidth. One of its applications is in generating waveform for the ECT (Electrical Capacitance Tomography) system. ECT is used to retrieve the details of material in a flow system. An economical PC Controlled Function Generator was designed for the use of waveform generating in ECT. For the ECT system, high accuracy and frequency waveforms are needed. Three basic waveforms are required; the sine wave, square wave, and triangular wave. The objective is to build a function generator which is capable of generating high accuracy waveforms with acceptable distortion and stability. An interfacing system between a PC and the function generator was also selected and developed with the purpose of producing accurate amplitude and frequency of the waveforms. This interfacing allows remote control to the function generator for a wider usage.

Key words: Function generator, direct digital synthesis (DDS)
A Fuzzy–Expert System For Classification Of Short Duration Voltage Disturbances
Authors: Mahdiraji Ghafour Amouzad , Mohamed Azah
Published: January 2013

Satu aspek penting dalam penilaian kualiti kuasa adalah pengesanan dan pengkelasan gangguan kualiti kuasa secara automatik yang memerlukan penggunaan teknik kepintaran buatan. Kertas kerja ini membentangkan penggunaan sistem pakar-kabur untuk pengkelasan gangguan voltan jangka masa pendek yang termasuk lendut voltan, ampul dan sampukan. Untuk memperolehi sifat unik bagi gangguan voltan, analisis jelmaan Fourier pantas dan teknik purataan punca min kuasa dua digunakan untuk menentukan parameter gangguan seperti tempoh masa, magnitud voltan pmk maksimum dan minimum. Berasaskan pada parameter ini, sebuah sistem pakar–kabur telah dibangunkan dengan mengset aturan kabur yang menimbangkan lima masukan dan tiga keluaran. Sistem ini direka bentuk untuk mengesan dan mengkelaskan tiga jenis gangguan voltan tempoh masa pendek dengan menentukan sama ada gangguan adalah gangguan ketika, gangguan seketika dan bukan gangguan lendut, ampul dan sampukan. Untuk mengesahkan kejituan sistem yang dicadangkan, ia telah diuji dengan gangguan voltan yang diperolehi dari pengawasan. Keputusan ujian menunjukkan bahawa sistem pakar–kabur yang dibangunkan telah memberikan kadar pengkelasan yang betul sebanyak 98.4 %.

Kata kunci: Kualiti kuasa, sistem pakar–kabur, lendut, ampul dan sampukan

One of the important aspects in power quality assessment is automated detection and classification of power quality disturbances which requires the use of artificial intelligent techniques. This paper presents the application of fuzzy–expert system for classification of short duration voltage disturbances which include voltage sag, swell and interruption. To obtain unique features of the voltage disturbances, fast Fourier transform analysis and root mean square averaging technique are utilized so as to determine the disturbance parameters such as duration, maximum and minimum rms voltage magnitudes. Based on these parameters, a fuzzy-expert system has been developed to set the fuzzy rules incorporating five inputs and three outputs. The system is designed for detecting and classifying the three types of short duration voltage disturbances, so as to determine whether the disturbance is instantaneous, momentary and non sag, swell and interruption. To verify the accuracy of the proposed system, it has been tested with recorded voltage disturbances obtained from monitoring. Tests results showed that the developed fuzzy–expert system gives a correct classification rate of 98.4 %.

Key words: Power quality, fuzzy–expert system, sag, swell and interruption.
An Active Learning Approach For Radial Basis Function Neural Networks
Authors: Abdullah S. S. , Allwright J. C.
Published: January 2013

Kertas kerja ini membentangkan satu kaedah Pembelajaran Aktif yang baru untuk melatih Jaringan Saraf Buatan ( JSB) yang berasaskan Fungsi Asas Jejarian (FAJ) apabila JSB tersebut digunakan untuk menyelesaikan masalah Penurunan Model. Kaedah baru ini berasaskan andaian bahawa data yang diperlukan, y, pada input x, berada dalam sebuah set di mana F(x) boleh dibentuk menggunakan pengalaman atau pengetahuan awal tentang satu masalah. Kaedah baru ini akan mendapatkan lokasi data baru dengan meminimumkan ralat kes paling buruk antara keluaran JSB dengan had data seperti yang telah ditakrifkan oleh set F(x). Adalah didapati bahawa kaedah yang dicadangkan ini mampu memberikan kedudukan data baru yang baik pada kes-kes tertentu, berbanding dengan data yang diperolehi daripada kaedah sedia ada. Hasil kajian perbandingan antara kaedah yang dicadangkan dengan kaedah yang sedia ada juga disertakan dalam kertas kerja ini yang menunjukkan bahawa kaedah pembelajaran aktif yang dicadangkan merupakan satu penambahan yang baik kepada kaedah pembelajaran aktif yang sedia ada seperti kaedah reka bentuk maksimum minimum atau kaedah cross validation.

Kata kunci: Jaringan saraf buatan, fungsi asas jejarian, penurunan model, kaedah pembelajaran aktif, reka bentuk eksperimen, metamodel

This paper presents a new Active Learning algorithm to train Radial Basis Function (RBF) Artificial Neural Networks (ANN) for model reduction problems. The new approach is based on the assumption that the unobserved training data y at input x, lies within a set where F(x) is known from experience or past simulations. The new approach finds the location of the new sample such that the worst case error between the output of the resulting RBF ANN and the bounds of the unknown data as specified by F(x) is minimized. This paper illustrates the new approach for the case when . It was found that it is possible to find a good location for the new data sample by using the suggested approach in certain cases. A comparative study was also done indicating that the new experiment design approach is a good complement to the existing ones such as cross validation design and maximum minimum design.

Key words: Artificial neural networks, radial basis functions, model reduction, active learning, experiment design, metamodeling
Complex Shape Measurement Using 3D Scanner
Authors: O.K. Rahmat Rahmita Wirza , Ng Seng Beng , Sangaralingam Kamini
Published: January 2013

Sistem Pemeriksaan Automatik biasanya bermula dengan teknik Reka bentuk Berbantukan Komputer (CAD) dan berakhir dengan janaan arahan mesin untuk menukarkan bahan mentah kepada produk akhir, memperolehi data tiga dimensi untuk membina model permukaan berparameter bagi tujuan analisis ralat, duplikasi atau memperbaiki objek tersebut. Ia melibatkan pendigitalan permukaan objek yang perlu diperiksa, janaan model CAD dan analisis keputusan pemeriksaan. Pendigitalan boleh dilakukan dengan teknik kuar sentuh atau pengesan tanpa sentuh. Biasanya, tanpa bantuan daripada pengeluar, adalah sukar untuk memantau dan mengenal pasti perubahan produk selepas digunakan. Tambahan pula, reka bentuk cetakan asal tidak didedahkan. Objektif utama kertas ini ialah mencadangkan suatu algoritma yang mampu mengekstrak maklumat daripada objek berbentuk kompleks yang telah didigitalkan (dengan menggunakan pengimbas laser), misalnya cangkukan lutut, untuk menjanakan reka bentuk cetakannya. Diharapkan penyelidik lain, terutamanya dalam bidang perubatan dan bio-kejuruteraan mendapat manfaat daripada algoritma ini untuk meramal dan menganggar perubahan bekas cangkukan perubatan dan seterusnya mengubah reka bentuknya untuk memenuhi kehendak pesakit.

Kata kunci: Pemeriksaan automatik, reka bentuk cetakan, cangkukan lutut, pengimbas 3D, gantian lutut total

Automated inspection systems usually start from computer-aided design (CAD) techniques, and end with either generation of machining instructions required to convert a raw material into a finished product, or to obtain three-dimensional data for constructing a parametric surface model of the product for the purpose of error analysis, or to duplicate or enhance the object. It involves surface digitization of an existing part that needs inspection, CAD model creation and analyzing the inspection results. Most of the time, without the help from the manufacturer, it is very difficult to do inspection and to detect any changes of the product after being used. In addition, the original blueprints of most manufacturing products are not being revealed to the public. The main objective of this paper is to propose an algorithm that is able to extract information from digitized complex shape objects (using laser scanner), such as the medical knee implant (knee prosthesis), to generate their blueprint. It is hoped that other researchers, especially in the medical and bioengineering field, can benefit from this proposed algorithm to predict or approximate the changes of the medical ex-plant and modify its design to suit the patient needs.

Key words: Automated inspection, blueprint, prosthesis, 3D scanner, total knee replacement
Optimization of Critical Medium Components for the Expression of Recombinant Human Transferrin in Insect Cells Baculovirus System
Authors: Ongkudon Clarence M. , Abdul Rahman Badarulhisam , Abd. Aziz Azila
Published: January 2013

Transferin manusia (hTf) memainkan peranan yang penting dalam fungsi bakteriostatik dan pengangkutan ferum dari bahagian penyimpanan ke sel–sel yang membiak melalui proses endositosis janaan reseptor. Sistem ekspresi bakulovirus sel serangga telah dipakai secara meluas sebagai sistem alternatif dalam penghasilan Transferin manusia rekombinan (rhTf). Kajian ini ditumpukan ke atas pengoptimuman glutamina, glukosa dan campuran lipid 1000x yang dapat meningkatkan penghasilan rhTf. Reka bentuk eksperimen yang melibatkan 17 eksperimen reka bentuk komposit berpusat (CCD) telah digunakan dan hasil kajian dianalisis oleh Statistika (Statsoft v. 5.0). Metodologi permukaan tindak balas (RSM) telah mengenalpasti nilai optimum parameterparameter yang dikaji iaitu glutamina=2211.20 mg/L, glukosa=1291.95 mg/L, dan campuran lipid 1000x=0.64 %v/v. Hasil optimasi menunjukkan peningkatan hasil rhTf sebanyak tiga kali ganda, iaitu daripada 19.89 μg/ml kepada 65.12 μg/ml.

Kata kunci: Transferin manusia; bakulovirus sel serangga; reka bentuk eksperimen; reka bentuk komposit berpusat; metodologi permukaan tindak balas

Human Transferrin (hTf) plays a big role in providing bacteriostatic functions as well as to transport iron from the storage part to all proliferating cells by receptor mediated endocytosis. Insect cells baculovirus expression system has been widely used as an alternative expression system for the production of recombinant human Transferrin (rhTf). This work focused mainly on the optimization of glutamine, glucose and lipid mixtures 1000x to increase rhTf yield. An experimental design involving 17 central composite design (CCD) experiments was employed and results were analyzed by Statistica (Statsoft v. 5.0). The response surface methodology (RSM) had identified the optimum values where glutamine=2211.20 mg/L, glucose=1291.95 mg/L, and lipid mixtures 1000x=0.64 %v/v. Using the optimized parameters, the studies demonstrated an increase in the rhTf yield by three–fold from 19.89 μg/ml to 65.12 μg/ml.

Key words: Human transferrin; insect cells baculovirus; experimental design; central composite design; response surface methodology
Photodegradation of New Methylene Blue N in Aqueous Solution Using Zinc Oxide and Titanium Dioxide as Catalyst
Authors: Ali Rusmidah , Ooi Boon Siew
Published: January 2013

Dalam kajian ini, ZnO dan TiO2 digunakan sebagai fotomangkin dalam pendegradasian pewarna New Methylene Blue N (NMBN). Kadar fotodegradasi diukur menggunakan alat spektrofotometer UV-Vis. Dalam kajian ini, New Methylene Blue N menunjukkan nilai serapan pada λ = 590 nm dan λ = 286 nm. Lampu UV (λ = 354 nm) digunakan dalam proses fotodegradasi. Dalam proses degradasi menggunakan ZnO menunjukkan 81.42% NMBN terdegradasi pada λ = 590 nm dan 77.75% pada λ = 286 nm. Sebaliknya, degradasi menggunakan TiO2 adalah 25.68% pada λ = 590 nm dan 26.37% pada λ = 286 nm. Peratus degradasi New Methylene Blue N ialah 88.89% dan 68.94% pada masing-masing λ = 590 nm dan λ = 286 nm apabila ditambahkan dengan H2O2. Campuran ZnO dan TiO2 dalam nisbah 85: 15 (0.085 g; 0.015 g) merupakan campuran fotomangkin yang paling optimum iaitu dengan peratus degradasi NMBN sebanyak 96.97% dan 93.61% pada λ = 590 nm dan λ = 286 nm. Penambahan ion logam Cu2+ memberikan peratus degradasi tertinggi berbanding ion logam lain iaitu 83.83% pada λ = 590 nm. Penambahan ion logam Pb2+ memberikan peratus degradasi tertinggi pada λ = 286 nm iaitu 81.25% pewarna terdegradasi. Keadaan optimum dicapai pada pH 5.90, dengan peratus degradasi tertinggi iaitu 92.84% dan 89.30% pada masing-masing λ = 590 nm dan λ = 286 nm.

Kata kunci: New Methylene Blue N; fotodegradasi; larutan; ZnO; TiO2

In this study, ZnO and TiO2 are used as photocatalyst to degrade the dye, New Methylene Blue N (NMBN). The photodegradation rate was measured using UV-Visible spectrophotometer. In this study, New Methylene Blue N showed absorption values at λ = 590 nm and λ = 286 nm. UV lamp (λ = 354 nm) is used in the photodegradation process. Results showed that ZnO is a better photocatalyst compared to TiO2. The degradation by ZnO showed that 81% of NMBN was degraded at λ = 590 nm and 77.75% at λ = 286 nm. In contratst, the degradation using TiO2 was 25.68% at λ = 590 nm and 26.37% at λ = 286 nm. The percent degradation of New Methylene Blue N is 88.89% and 68.94% at λ = 590 nm and λ = 286 nm respectively when H2O2 was added. A mixture of ZnO and TiO2 in the ratio of 85: 15 (0.085 g: 0.015 g) is the most optimum ratio for the mixed photocatalyst where the degradation percentage of NMBN are 96.97% and 93.61% at λ = 590 nm and λ = 286 nm. The addition of Cu2+ metal ion gave the highest percentage of degradation (83.83% at λ = 590 nm) compared to other metal ions. The addition of Pb2+ gave the highest percentage of degradation at λ = 286 nm with 81.25% degradation of the dye. The optimum condition was achieved at pH 5.90, which gave the highest percentage degradation, 92.84% and 89.30% at λ = 590 nm and λ = 286 nm respectively.

Key words: New Methylene Blue N; photodegradation; aqueous; ZnO; TiO2
Comperative Performances of Single and Dual Media Filters of Sand and Burnt Oil Palm Shell
Authors: Jusoh Ahmad , S. Goh Eng Giap , Nora’aini A. , Halim A. G. , Noor M. J. M. M. , Zakaria M. P.
Published: January 2013

Penurasan merupakan unit operasi utama bagi loji olahan air. Media penuras yang lazim digunakan adalah berbentuk butiran seperti pasir, antrasit, arang, magnetik, garnit dan tempurung kelapa. Prestasi penuras media berbentuk butiran telah terbukti berkesan. Walau bagaimanapun, keperluan media penuras alternatif yang kos efektif masih diperlukan memandangkan kos operasi dan kos pengeluaran air sentiasa meningkat dari semasa ke semasa. Dewasa ini kajian telahpun dijalankan terhadap potensi butiran arang tempurung kelapa sawit sebagai media penuras. Bahan ini merupakan sisa buangan pepejal yang terdapat dengan banyaknya hasil dari pemprosesan industri minyak sawit. Dalam kajian ini, pasir dan butiran arang tempurung kelapa sawit (BOPS) telah digunakan sebagai penuras satu-media dan penuras dua-media pada beberapa saiz efektif, Es (iaitu Es 0.4 dan 0.6 untuk pasir, Es 1.0 dan 2.0 untuk BOPS) dan kadar alir (iaitu 10 dan 15 m3/m2.jam). Prestasi penurasan adalah dipengaruhi oleh ketebalan penuras, kualiti air influen, kadar alir air dan saiz efektif media penuras. Keputusan menunjukkan bahawa penuras mampu menghasilkan kualiti air yang tinggi (
Effect of Nano–Precipitated Calcium Carbonate on Mechanical Properties of PVC–U/Acrylic Blend
Authors: Abu Bakar Aznizam , Mohmed Rosli Nurul Nazihah
Published: January 2013

Perkembangan nanokomposit berasaskan polimer dan pengisi bersaiz nano telah menjadi pendekatan yang menarik untuk mencapai sifat komposit yang baik. Kesan nano–termendak kalsium karbonat (NPCC) terhadap sifat mekanikal matrik berlainan kemuluran telah dikaji. Poli(vinil klorida) tanpa pemplastik (PVC–U) dan PVC–U/akrilik telah digunakan sebagai matrik pada kajian ini. Untuk menghasilkan komposit, resin PVC, additif, akrilik dan NPCC pada mulanya diadun-kering menggunakan pencampur berkelajuan–tinggi berskala makmal sebelum diadun menjadi kepingan dengan menggunakan pengadun dua pengguling. Spesimen–spesimen ujian kemudiannya ditekan panas, selepas itu sifat mekanikal komposit dan morfologi permukaan patah komposit ditentukan. Modulus lenturan dan modulus Young meningkat dengan penambahan NPCC, tetapi telah menurunkan kekuatan regangan. NPCC telah menunjukkan kesan pengukuhan yang baik pada matrik PVC–U/ akrilik dan kesan kekakuan yang baik pada matrik PVC–U. Kekuatan lenturan kedua–dua komposit tidak dipengaruhi dengan penambahan NPCC. Kekuatan hentaman kedua–dua komposit telah mencapai nilai maksimum apabila 15 phr NPCC ditambah.

Kata kunci: Poli(vinil klorida), nano–termendak kalsium karbonat, sifat–sifat mekanikal, akrilik

Developing nanocomposites based upon polymers and nano–sized fillers has been an attractive approach to achieving good properties. Effects of nano–precipitated calcium carbonate (NPCC) on the mechanical properties of different ductile matrices were investigated. Unplasticised Poly(vinyl chloride) (PVC–U) and PVC–U/acrylic were used as the matrix in this study. To produce the composites, PVC resins, additives, acrylic and NPCC were first dry–blended using a laboratory high–speed mixer before being milled into sheets on a two–roll mill. Test specimens were then hot pressed, after that the mechanical properties and morphology of fracture surface of composites were determined. The flexural modulus and Young modulus of both the composites were enhanced after the addition of NPCC, but the tensile strength was decreased. The NPCC showed good toughening effect and stiffening effect on PVC–U/acrylic and PVC–U matrix, respectively. The flexural strength of both the composites was not significantly affected by the addition of NPCC. The impact strength of both the composites reached the maximum value when 15 phr NPCC was incorporated.

Key words: Poly(vinyl chloride), nano–precipitated calcium carbonate, mechanical properties, acrylic
The Dynamics of Fundamentals in Currency Crisis in Indonesia and Malaysia
Authors: Lim Guan Choo
Published: January 2013

Kesan makroekonomi fundamental ke atas tekanan pasaran (MP) ditafsir menggunakan model generasi ketiga berasaskan jangkaan ‘adaptif’ Dusenberry. Hasil kajian ini tekal dengan anggapan umum bahawa fundamental makroekonomi yang lemah telah mengakibatkan serangan ke atas matawang negara–negara Asia. Walau bagaimanapun, variabel makroekonomi serta dinamik variabel tersebut yang membawa kepada krisis agak berbeza di Malaysia dan Indonesia. Serangan spekulatif terhadap rupiah berlaku dalam keadaan makroekonomi yang lemah manakala tekanan terhadap Ringgit Malaysia dikaitkan dengan pertumbuhan kredit, defisit fiskal dan kadar pertukaran benar. Kesimpulannya, fundamental yang mempengaruhi jangkaan pasaran dan seterusnya tekanan pasaran (MP) mungkin sama tetapi dinamik yang membentuk jangkaan pasaran amat berbeza. Oleh yang demikian, anggapan bahawa ekonomi Asian mempunyai ciri–ciri yang sama sehingga mengakibatkan krisis matawang 1997 mungkin tidak benar.

Kata kunci: krisis matawang; Indonesia; Malaysia; fundamental

The impact of selected macroeconomic fundamentals on the market pressure (MP) is assessed using the third generation models based on ‘Dusenberry’ adaptive expectations. The findings are consistent with the general belief that weak macroeconomic fundamentals had triggered the speculative attacks against the Asian currencies. However, the macroeconomic variables and their dynamics that set the groundwork for a currency crisis differ considerably in Malaysia and Indonesia. A speculative attack against the Rupiah occurred in a generalized state of macroeconomic weakness while domestic credit growth, the fiscal balances–GDP ratio and the real exchange rate exerted strong influence on the exchange market pressure for Malaysia. In conclusion, while there are some common fundamentals matter for shifting market expectations and hence, market pressure in both countries, the dynamics that formed market expectations are divergent. Therefore, the belief that the Asian economies had the same characteristics that triggered the currency crisis in 1997 may be incorrect.

Key words: currency crisis; Indonesia; Malaysia; fundamentals
The Performance Of Semi–Metallic Friction Materials For Passenger Cars
Authors: Talib Ria Jaafar , Muchtar Andanastuti , Azhari Che Husna
Published: January 2013

Dalam kajian ini, penilaian haus mekanikal ke atas bahan geseran separa logam untuk kegunaan kereta penumpang dikaji dengan menekan sampel kepada piring yang berpusing diperbuat daripada besi tuang kelabu pearlitik. Bagi setiap ujian, sampel dikenakan empat jangka masa pembrekan (3, 6, 9, dan 12 minit) dan empat beban kenaan (200, 400, 600 dan 800 N) yang berlainan. Kelajuan putaran piring brek dikekalkan malar sepanjang pengujian geseran pada 750 psm. Selepas setiap ujian, perubahan morfologi permukaan dan subpermukaan diperhatikan dengan menggunakan mikroskop elektron imbasan (MEI). Hasil kajian menunjukkan ciri-ciri berikut: (i) suhu permukaan meningkat dengan masa pembrekan dan selepas mencapai nilai maksimum, akhirnya sampai kepada keadaan stabil, (ii) pekali geseran telah meningkat pada permulaan pembrekan, kemudian menurun dengan masa pembrekan, dan seterusnya sampai kepada keadaan stabil, dan (iii) isipadu haus meningkat secara lelurus apabila beban kenaan di bawah 200 N dan/atau masa pembrekan di bawah 3 minit dan kedua-duanya seterusnya meningkat secara eksponen. Pemeriksaan mikrostruktur menunjukkan mekanisme haus beralih dengan peningkatan jangka masa pembrekan dan beban kenaan. Fenomena ini juga menyebabkan perubahan kepada sifat haus.

Kata kunci: Pad brek, suhu permukaan, pekali geseran, haus, mekanisme haus

In this work, a semi-metallic friction material for passenger cars was evaluated for mechanical wear by pressing the material against a rotating pearlitic gray cast iron brake disc. In each test, the sample was subjected to four different braking times (3, 6, 9, and 12 minutes) and four applied loads (200, 400, 600 and 800 N). The rotating velocity of the disc was kept constant throughout the friction tests at 750 rpm. After each test, the morphological changes on the surface and subsurface of the material were observed using Scanning Electron Microscopy (SEM). The following characteristics were observed: (i) the surface temperature increased with braking time and after reaching a maximum value, eventually arrived at a steady state, (ii) the friction coefficient increased at the early stages of braking, then decreased with braking time and thereafter reached steady state, and (iii) the wear volume increased linearly when the applied load was below 200 N and/or braking time was below 3 minutes or both, thereafter the volume increased exponentially. Microstructural examinations showed that the wear mechanism transisted with increase in braking times as well as applied loads. This phenomenon also resulted in changes of the wear behaviour.

Key words: Brake pad, surface temperature, friction coefficient, wear, wear mechanism
Wetting Properties of Sn–Pb, Sn–Zn and Sn–Zn–Bi Lead–Free Solders
Authors: Appan Ramani May , Ismail Ahmad Badri , Ahmad Zainal Arifin , Ariga Tadashi , Hussain Luay Bakir
Published: January 2013

Tiga kajian terhadap Sn–40Pb, Sn–9Zn dan Sn–8Zn–3Bi pateri tanpa plumbum telah dijalankan. Penyebaran pateri–pateri ini dikaji terhadap substrat Cu yang mempunyai kekasaran 0.13 μm pada suhu 250°C. Sn–40Pb mempunyai sudut sentuhan bernilai °6, iaitu tujuh kali lebih baik berbanding pateri–pateri Sn–Zn dan Sn–8Zn–3Bi. Tetimbang basahan digunakan untuk mengkaji tempoh dan daya basahan serta ketegangan permukaan pada suhu yang berlainan menggunakan dua fluks yang berbeza. Untuk pateri Sn–8Zn–3Bi, fluks MHS (nama komersial) memberi daya dan tempoh basahan yang lebih tinggi berbanding dengan fluks HCl untuk suhu yang meningkat. Ketegangan permukaan untuk pateri Sn–40Pb berkurangan apabila suhu meningkat tetapi suhu tidak mempengaruhi ketegangan permukaan untuk pateri Sn–9Pb dan Sn–8Zn–3Bi. Walau bagaimanapun, tambahan 3% Bi mengurangkan ketegangan permukaan sistem Sn–Zn–Bi. Satu kajian dilakukan mengenai penyebaran pateri aloi Sn-9Pb ke atas permukaan Cu bagi kekasaran permukaan antara 0.33 dengan 1.53 μm. Didapati bahawa kekasaran permukaan di bawah 0.62 μm tidak membantu dalam peningkatan basahan, tetapi kekerasan melebihi 0.62 μm meningkatkan sudut basahan dan luas penyebaran.

Kata kunci: Pateri tanpa plumbum, penyebaran, kekasaran, sifat–sifat basahan, ketegangan permukaan

Three studies on Sn–40Pb, Sn–9Zn and Sn–8Zn–3Bi Pb–free solders were conductwd. Spreading of the solders was investigated on 0.13 μm roughness Cu subrate at 250°C. Sn–40Pb has a contact angle of 6°, which is seven times better than Sn–9Zn and Sn–8Zn–3Bi solders. Wetting balance was uesd to study the wetting time, wetting force and surface tension at different temperatures using two different fluxes. For Sn–8Zn–3Bi solder, MHS (commercial name) flux gives higher wetting force and wetting time compared to HCl flux for increasing temperatures. The surface tension of Sn–40Pb solder decreased with increasing temperature whereas the surface tension of Sn–9Zn and Sn–8Zn–3Bi solders is not influenced by the temperature. However, the addition of 3% Bi reduces the surface tension of the Sn–Zn–Bi system. A study on the spreading of Sn–9Zn solder alloy on Cu with surface roughness between 0.33 and 1.53 μm was also conducted. Surface roughness below 0.62 μm, there was an improvemenet in the contact angle and spreading area.

Key words: Pb–free solder, spreading, rougness, wetting properties, surface tension
Unsteady Boundary Layer Flow of A Micropolar Fluid Near A Stagnation Point With Uniform Suction Or Injection
Authors: Lok Yian Yian , Amin Norsarahaida , Pop Ioan
Published: January 2013

Kertas kerja ini mengkaji kesan sedutan dan suntikan ke atas aliran lapisan sempadan tak mantap di titik genangan depan dinding boleh telap bagi bendalir mikropolar. Halaju aliran luar serta halaju sedutan dan suntikan diandaikan bermula secara dedunyut, seterusnya manjadi malar selepas aliran mula bergerak. Masalah ini dimodelkan oleh persamaan terbitan separa yang perlu diselesaiakn secara berangka untuk beberapa nilai sedutan, suntikan dan parameter bahan. Taburan halaju, mikroputaran dan pekali geseran permukaan dipersembahkan dalam bentuk jadual dan gambar rajah. Hasil kajian menunjukkan kesan sedutan dapat meningkatkan nilai sedutan dan suntikan, kesan mikroputaran berdekatan dinding dapat diperlambatkan. Di samping itu, suntikan didapati memerlukan lebih banyak masa untuk mencapai aliran mantap berbanding sedutan.

Kata kunci: Aliran lapisan sempadan tak mantap, bendalir mikropolar, titik genangan depan, sedutan, suntikan

This paper studies the effect of suction or injection on unsteady boundary layer flow of micropolar fluid near the forward stagnation point of a permeable wall. The velocity of the external flow as well as that of suction or injection are assumed to start impulsively from rest and are maintained thereafter. The model is governed by a set of coupled partial different equations that is solved numerically for some values of the suction, injection and material parameters. Profiles for the velocity, microrotation and skin friction coenfficient are determined and presented in tables and graphical forms. The results show that suction increases the skin friction while the opposite behaviour is observed for the case of injection. It is also found that an increase in the material parameter will enchance the flow near the wall. On the other hand, it can be seen that in the case of injection, longer time is required to approach the steady flow than in the case of suction.

Key words: Unsteady boundary layer flow, micropolar fluid, forward stagnation point, suction, injection
Fitting The Best–Fit Distribution For The Hourly Rainfall Amount In The Wilayah Persekutuan
Authors: Y. Fadhilah , Md. Zalina , V–T–V. Nguyen , S. Suhaila , Y. Zulkifli
Published: January 2013

Dalam mengenal pasti model yang terbaik untuk mewakili taburan jumlah hujan bagi data selang masa satu jam di 12 stesen di Wilayah Persekutuan empat taburan digunakan iaitu Taburan Eksponen, Gamma, Weibull dan Gabungan Eksponen. Parameter–parameter dianggar menggunakan kaedah kebolehjadian maksimum. Model yang terbaik dipilih berdasarkan nilai minimum yang diperolehi daripada ujian–ujian kebagusan penyuaian yang digunakan dalam kajian ini. Ujian ini dipertahankan lagi dengan plot kebarangkalian dilampaui. Taburan Gabungan Eksponen di dapati paling baik untuk mewakili taburan jumlah hujan dalam selang masa satu jam. Daripada anggaran parameter bagi taburan Gabungan Eksponen ini, boleh diterjemah bahawa jumlah hujan tertinggi yang direkodkan diperolehi daripada hujan yang dikategorikan sebagai hujan lebat, walaupun hujan renyai–renyai berlaku lebih kerap.

Kata kunci: Jumlah hujan dalam selang masa sejam, ujian kebagusan penyuaian, kebolehjadian maksimum

In determining the best–fit model for the hourly rainfall amounts for the twelve stations in the Wilayah Persekutuan, four distributions namely, the Exponential, Gamma, Weibull and Mixed–Exponential were used. Parameters for each distribution were estimated using the maximum likelihood method. The best–fit model was chosen based upon the minimum error produced by the goodness–offit tests used in this study. The tests were justified further by the exceedance probability plot. The Mixed–Exponential was found to be the most appropriate distribution in describing the hourly rainfall amounts. From the parameter estimates for the Mixed–Exponential distribution, it could be implied that most of the hourly rainfall amount recorded were received from the heavy rainfall even though there was a high occurrences of light rainfall.

Key words: Hourly rainfall amount, goodness-of-fit test, exceedance probability, maximum likelihood
Comparison Analysis Of Stream Cipher Algorithms For Digital Communication
Authors: Mat Sidek Abd Rahim , Sha’ameri Ahmad Zuri
Published: January 2013

Penghantaran maklumat dalam sistem komunikasi radio seperti frekuensi tinggi akan mendedahkan maklumat itu kepada pihak–pihak yang tidak berkaitan. Untuk memastikan maklumat tersebut selamat, ia haruslah dienkodkan terlebih dahulu sebelum dihantar. Bagi maklumat bersaiz besar, pengenkod jenis satu bit adalah lebih sesuai berbanding pengenkod jenis blok kerana ia lebih cepat dan tidak mempengaruhi bit bersebelahan jika berlakunya kesilapan semasa penghantaran. Pengenkod satu bit biasanya dihasilkan menggunakan kaedah anjakan balik secara linear dan juga penggabungan secara tidak linear. Dengan menggunakan panjang kunci yang sama untuk setiap pengenkod iaitu 64 bit, kekuatan pengenkod ditentukan dengan menggunakan beberapa jenis ujian piawaian. Pengenkod yang melepasi kesemua ujian adalah yang paling baik dan sesuai untuk digunakan dalam penghantaran maklumat digital.

Kata kunci: Penghantaran, pengenkod, komunikasi, selamat, linear

The broadcast nature of radio communication such as in the HF (High Frequency) spectrum exposes the transmitted information to unauthorized third parties. Confidentiality is ensured by employing cipher system. For bulk transmission of data, stream ciphers are ideal choices over block ciphers due to faster implementation speed and not introducing error propagation. The stream cipher algorithms evaluated are based on the linear feedback shift register (LFSR) with nonlinear combining function. By using a common key length and worst case conditions, the strength of several stream cipher algorithms are evaluated using statistical tests, correlation attack, linear complexity profile and nonstandard test. The best algorithm is the one that exceeds all of the tests.

Key words: Confidential, LFSR, stream, block, correlation
Active Log Periodic Antenna
Authors: A. Rahim Mohamad Kamal
Published: January 2013

This paper describes four different configurations of active devices integration into log periodic antennas (LPAs). The first configuration involves the integration of a single amplifier at the input feed line of a five element log periodic antenna (LPA). The second configuration involves the integration of an amplifier in the middle of the five elements LPA. The third configuration is the five element LPA with individual amplifiers in each element. The last configuration involves the integration of the individual amplifiers and filters with five element LPA in each element. The performance of these configurations have been investigated and compared in terms of the bandwidth, gain relative to a passive LPA, cross polar isolation and half power beamwidth.

Key words: Log periodic antenna, active integrated antenna, microstrip antenna, wideband antenna