Showing papers by "Universiti Teknologi Petronas published in 2006"

Inherent safety tool for explosion consequences study

Abstract: The lack of formal integration between process design stages with risk and consequence estimation is a hurdle to designing inherently safe process plants. Conventional risk assessment methodologies are often not carried out concurrently with process design. Therefore, process designers lack the information about risk levels and consequence that may result from the process conditions being considered in a particular process route until the design is completed. Hence, effects of changes in process conditions on risk levels and consequence cannot be studied in a time effective manner during the design stages. Few studies have been identified on the possibility and viability of integrating risk estimation with process design. But viable framework and methodology for doing so has not yet been reported. This paper presents a feasible framework in which risk and consequences estimation can be part of design stages. A demonstrative tool named as integrated risk estimation tool (iRET) was developed by using process simulation software, HYSYS and spreadsheet, MS Excel as the platforms. iRET estimates risk due to explosions by using TNT equivalence method and the TNO correlation method. iRET has a potential to be extended to include all forms of risk such as fire, explosion, toxic gas releases and boiling liquid expanding vapour explosion (BLEVE). The paper also presents case studies to demonstrate the functionality and viability of using iRET in conjunction with process design. The results of these case studies have successfully shown that the risk due to explosion can be assessed during the initial design stage ensuring a safer plant. The framework and iRET there by presented here provide systematic methodology and technology to design inherently safer plants.

Recycle Polypropylene (RPP) - Wood Saw Dust (WSD) Composites - Part 1: The Effect of Different Filler Size and Filler Loading on Mechanical and Water Absorption Properties

Abstract: The compounding of recycled polypropylene (RPP) and wood saw dust (WSD) are carried out using five different filler loadings (0, 10, 20, 30, 40, and 50%) with three WSD filler sizes (100, 212, and 300 mm). The composites are mixed and extruded using Haake Rheodrive 500 twin screw extruder. The mechanical and water absorption properties of composites are characterized accordingly. The results show that composites with a smaller particle size (100 mm) have remarkably higher properties compared to others (212 and 300 mm). Composites filled up to 30% WSD exhibits improved mechanical properties but the value dramatically decreased above 30% filler loading. The evidence of fiber-matrix interphase is analyzed using scanning electron microscope (SEM).

Structure and Dynamic Mechanical Properties of Melt Intercalated Polyamide 6—Montmorillonite Nanocomposites

Abstract: Polymer-layered silicate nanocomposites (PLSN), based on polyamide 6 (PA6) and montmorillonite (MMT) modified with an octadecylammonium salt, were produced via melt compounding in a co-rotating twin-screw extruder. Wide angle X-ray diffraction (WAXD) and TEM revealed a PLSN containing 3.3% by weight (wt.-%) of MMT to exhibit a mixed exfoliated/intercalated morphology, consisting mainly of individual silicate lamellae together with some intercalated stacks, resulting in a mean value of 1.8 lamellae per particle. In contrast, a PLSN containing a higher level of 7.2 wt.-% MMT exhibited a more ordered intercalated structure, consisting mainly of a distribution of lamellae stacks with a mean value of 3.8 lamellae per particle. The dispersion of MMT in the PLSN generated very large polymer-filler interfacial areas, resulting in significant increase in the volume of constrained PA6 chain segments. Consequently, significant changes in the ratio of α/γ crystallites and in the thermal behaviour of the matrix PA6 were observed during WAXD, DSC and dynamic-mechanical thermal analysis (DMTA) studies of the PLSN. In particular, damping data from DMTA showed relaxations between T g and T m resulting from amorphous polymer chain segments constrained at the polymer-filler interface, indicating the formation of a continuous phase of constrained polymer. In contrast, a PA6 microcomposite formed using unmodified MMT generated much lower polymer-filler interfacial area, with most of the MMT residing within large, poorly wetted aggregates. Consequently, changes to the thermal behaviour of the matrix PA6 were much less significant than those induced in the PLSN.

Fuzzy Production Planning and its Application to Decision Making

Abstract: This paper presents new methods for solving a production-planning problem. First the modified s-curve membership function as a methodology is constructed. Then fuzzy production planning problems with vagueness parameters alpha and fuzzy objective coefficients, fuzzy technical coefficients and fuzzy resource variables are outlined. The objective of this paper is to find a satisfactory solution for optimal profit in which vagueness is playing major factor in selecting the solution. Finally a practical application of decision-making in production planning is illustrated.

The influence of temperature on adsorption capacity of Malaysian coal

Abstract: The paper highlights the study of carbon dioxide (CO2) adsorption profiles of local coal samples of varying mean size distributions (1000 and 2000 μm) obtained from Miri, Sarawak situated in the East of Malaysia, at different temperatures (24.6, 30, 40 and 55 °C). Parameters such as the moisture content, ash content, carbon content and mineral content of the coal sample are investigated. Based on the physical analysis of the coal, it was classified as lignite, which exhibits a better adsorptive capability of CO2. In addition, the coal sample having the smaller mean particle size distribution of 1000 μm shows a better rate of adsorption compared to the 2000 μm size distribution. The adsorption capacity of the coal sample shows an inverse relationship with temperature. These findings open a platform for CO2 sequestration to be implemented in Malaysia.

Kinetics and Modelling of Cell Growth and Substrate Uptake in Centella asiatica Cell Culture

Abstract: In this study, we have conducted kinetics and modelling studies ofCentella asiatica cell growth and substrate uptake, in an attempt to evaluate cell growth for a better understanding and control of the process. In our bioreactor cultivation experiment, we observed a growth rate of 0.18/day, a value only 20% higher than was seen in the shake flask cultivation trial. However, the observed maximum cell dry weight in the shake flask, 10.5 g/L, was 14% higher than was achieved in the bioreactor. Ninety seven percentage confidence was achieved via the fitting of three unstructured growth models; the Monod, Logistic, and Gompertz equations, to the cell growth data. The Monod equation adequately described cell growth in both cultures. The specific growth rate, however, was not effectively predicted with the Logistic and Gompertz equations, which resulted in deviations of up to 73 and 393%, respectively. These deviations in the Logistic and Gompertz models may be attributable to the fact that these models were developed for substrate-independent growth and fungi growth, respectively.

Fuzzy optimization of units products in mix-product selection problem using fuzzy linear programming approach

Abstract: In this paper, the modified S-curve membership function methodology is used in a real life industrial problem of mix product selection. This problem occurs in the production planning management where by a decision maker plays important role in making decision in an uncertain environment. As analysts, we try to find a good enough solution for the decision maker to make a final decision. An industrial application of fuzzy linear programming (FLP) through the S-curve membership function has been investigated using a set of real life data collected from a Chocolate Manufacturing Company. The problem of fuzzy product mix selection has been defined. The objective of this paper is to find an optimal units of products with higher level of satisfaction with vagueness as a key factor. Since there are several decisions that were to be taken, a table for optimal units of products respect to vagueness and degree of satisfaction has been defined to identify the solution with higher level of units of products and with a higher degree of satisfaction. The fuzzy outcome shows that higher units of products need not lead to higher degree of satisfaction. The findings of this work indicates that the optimal decision is depend on vagueness factor in the fuzzy system of mix product selection problem. Further more the high level of units of products obtained when the vagueness is low.

A Theoretical and Experimental Investigation into the Development of Coverage in Shot Peening

Abstract: Shot peening is a mechanical surface treatment process used mainly for the improvement of the fatigue structural integrity of metallic components. In this process, the surface of a part is bombarded with small spherical media called shot, at high velocity, to induce desirable residual compressive stresses and strains within the surface layers of the component The effectiveness of the shot peemng process 1s dependent upon the uniformity of the induced compressive residual stresses and the energy transfer that occurs during the impact of the shots with the target surface. In practice, the process efficiency is established by means of coverage, intensity and saturation. Therefore, the scope of this study is to investigate the development of coverage and its relationship to intensity and saturation of peening. Within the scope, the objectives of the study are to compare and contrast the coverage results obtained experimentally with theoretical models, to establish a relationship between coverage and intensity and to obtain an empirical relationship to predict coverage. Theoretical models used to predict coverage give mixed results compared to experimental results. The Holdgate model gives a very good coverage prediction whereas the A vrami equation does not Coverage development is found to be a function of shot size, impingement angle and target material properties. Intensity and saturation time is found to be dependent upon shot size and impingement angle. Complete coverage is achieved earlier than the saturation point which 1s a contrast to the usual assumption that coverage and saturation occurs at the same time. However, a clear relationship could not be established. An empirical relationship can be used to predict coverage. This relationship, which is a function of the process parameters such as shot size and impingement angle, is established by using multiple regression analysis.

A Multi-Objective Evolutionary Approach for Fuzzy Optimization in Production Planning

Abstract: This paper outlines, first, a real-world industrial problem for product-mix selection involving 8 variables and 21 constraints with fuzzy coefficients and thereafter, a multi-objective optimization approach to solve the problem. This problem occurs in production planning in which a decision-maker plays a pivotal role in making decision under fuzzy environment. Decision-maker should be aware of his/her level-of-satisfaction as well as degree of fuzziness while making the product-mix decision. Thus, the authors have analyzed using a modified S-curve membership function the fuzziness patterns and fuzzy sensitivity of the solution found from the multi-objective optimization methodology. An ad hoc Pareto-based multi-objective evolutionary algorithm is proposed to capture multiple non dominated solutions in a single run of the algorithm. Results obtained have been compared with the well-known multi-objective evolutionary algorithm NSGA-II.

Meta-Learning evolutionary artificial neural network for selecting flexible manufacturing systems

Abstract: This paper proposes the application of Meta-Learning Evolutionary Artificial Neural Network (MLEANN) in selecting flexible manufacturing systems (FMS) from a group of candidate FMS’s. First, multi-criteria decisionmaking (MCDM) methodology using an improved S-shaped membership function has been developed for finding out the ‘best candidate FMS alternative’ from a set of candidate-FMSs. The MCDM model trade-offs among various parameters, namely, design parameters, economic considerations, etc., affecting the FMS selection process in multi-criteria decision-making environment. Genetic algorithm is used to evolve the architecture and weights of the proposed neural network method. Further, a back-propagation (BP) algorithm is used as the local search algorithm. The selection of FMS is made according to the error output of the results found from the MCDM model.

Sorption of Lead Ions from Aqueous Solution by Chickpea Leaves, Stems and Fruit Peelings

Abstract: Leaves, stems and fruit peelings of chickpea (Cicer arientinum L.) were successfully utilized for the accumulation of lead ions from aqueous solutions onto their surfaces. The rate and extent of accumulation were affected by pH, particle size, contact time and the initial concentration of Pb(II) ions, respectively. The sorption capacities of leaves, stems and fruit peelings towards Pb(II) ions were found to be 81.30, 80.10 and 53.26%, respectively, at an initial Pb(II) ion concentration of 200 mg/dm3, optimum pH conditions of 6.0, a particle size of 0.354 mm and a contact time of 120 min. Most of the sorption occurred within the first 15 min and attained a maximum value after 120 min. The Bangham equation was used to express the adsorption mechanism. The adsorption rates of Pb(II) ions were found to decrease in the order: leaves > stems > fruit peelings. Possible cell–metal ion interactions may be due to the involvement of –COOH, –OH and –NH groups in the sorption process. The obtained sorption data were ...

Modeling and optimization of Ammonia reactor using shooting methods

Abstract: Ammonia production depends on temperature of feed gas at the top of the reactor (top temperature), the partial pressures of the reactants and the reactor length The optimal design problem requires obtaining the optimal reactor length with maximum economic returns corresponding to a top temperature of 694K This paper presents an alternative approach in solving the boundary value problem and at the same time determines the optimal solution Shooting methods, namely single and multiple-shooting methods are used The software used for this modeling is MATLAB version 61 The ordinary differential equation (ODE) integration routine technique used is 'ode45' and the optimization routine of 'FMINCON' is selected for multiple-shooting The profiles of NN2, Tf and Tg at a top temperature of 694K were generated From the results obtained, this temperature yields an objective function value of $5015 × 106 per year at an optimum reactor length of 6695m The objective function and reactor length values agree with the latest literature work using Differential Evolution (DE) approach, and multiple-shooting performs better than single-shooting under bad initial guesses of the reactor length

Sn–Sb–Se crystalline phases formed by melt-quenching technique

Abstract: Preperation of alloy percentages of Sn-Sb-Se(TAS) of shaking furnace and melt sealing evacuated quartz ampoule using melt quenching technique (MQT) was analyzed. XRD measurement was carried out to identify whether the prepared samples were amorphous or crystalline structure and to determine the boundary between the two states. SEM morphological studies revealed that increasing Sn and Sb mole % modify the microstructure of the ternary Sn-Sb-Se based systems. Under the same conditions of preparation and maintaining Sn mol% at 15, the dendrite shapes of crystals were enlarged when Sb mol% increased. The Sn occurred in ternary compositions and supports the theoretical argument which considered Sb-mol %=14.3 is the boundary line between the crystalline and crystalline phase is dominant in the region with Sb-mol% more than or equal to 15. MQT proved its ability in preparing alloy of Sn-Sb-Se in crystalline structure and there was no excessive loss of the materials during the preparation.

Optimal Design of a Furnace Transformer by Genetic Algorithm

Abstract: This paper presents design optimization of a class of special purpose transformers used in direct-arc melting furnace, adopting genetic algorithm (GA) The operation and performance characteristics of a furnace transformer connected to a large direct arc furnace formed the basis for realizing the rating of the transformer The nonlinear mathematical model of the transformer is based on the core geometry available from manufacturer's published data In order to verify the effectiveness of GA method, an example is considered The results show the potential for implementation of GA as an efficient search technique for design optimization of transformers A discussion on the variation of GA parameters while minimizing the single and multi-objective functions satisfying the performance constraints concludes the paper

Slotted Triangular Patch Antenna for Reduced Reflection Loss

Abstract: In this paper, the reflection loss of a slotted triangular patch antenna is studied. The slotted triangular patch shows lower reflection loss compared to a conventional triangular patch antenna. Emphasize is given to lower the reflection loss at the broadside modes. Using this method, the potential of using a slotted triangular patch as a multiband patch antenna is further enhanced. Reduced reflection loss can be obtained not only at the broadside modes' resonant frequencies but also other higher order resonant frequencies. This is achieved by placing triangular slots nearby the magnetic field nulls. The patch antennas are simulated using HP High Frequency Structure Simulator (HFSS).

DWT based FFT in Practical OFDM Systems

Abstract: OFDM is a multi-carrier technique based on a very simple modulation scheme that uses IFFT and FFT at its core for transmission and reception respectively. The performance of the OFDM receiver is significantly affected in the presence of noise in the wireless channel. In this work a receiver that has built-in denoising capacity with little additional computation is proposed. It is based on a DWT based FFT algorithm. Experiments using MATLAB are conducted to verify the feasibility of this denoising algorithm on OFDM signals. The result shows noise suppression thus supports our claim.

Distance estimations in static images: does viewing distance matter?

Abstract: Previous research has examined the effect of display size on distance estimation in static images and demonstrated that display size affects participant's distance estimate task performance. Several other researches have also reported similar outcomes. Examination of the experimental setups of these early researchers suggests that other factors may also contribute to the effect. In this paper, we report our investigations that extend the earlier research by examining the contribution of other factor such as viewing distance and physiological cues. By fixing the viewing distance of the observer, our research indicates that viewing distance (and physiological cues) does influence distance estimation. The large magnitude of effect size for display size factor however suggested that display size still constitutes a major influence in distance estimation task

Fuzzy LP with a non-linear MF for product-mix solution: A case-based re-modelling and solution

Abstract: Makalah dipresentasikan pada The 9th Joint Conference on Information Sciences (JCIS). Kaohsiung, Taiwan, ROC, October 8 – 11, 2006

Optical Spectrum CDMA: A New Code Construction for Double Weight Code Family

Abstract: This paper handles the Double Weight (DW) Code family, one of the proposed codes used in Spectral-Amplitude-Coding Optical Code Division Multiple Access (OCDMA). The DW code family is constructed using a matrix technique which produces the whole basic code matrix in order to get a specified codeword. An additional mapping technique is used to increase the number of users. Both techniques add more complication to the code construction. A general equation is derived and analyzed in order to compare with the conventional method. Detailed examples are given on how to generate codes using a general equation. We also show in this paper the advantages of this formula compared to the existing construction technique. This newly designed technique allows us to use an equation-based constructing method to build any specified codeword for the DW code family.

Block Motion Estimation Using Directional Adaptive Search Window

Abstract: Motion estimation (ME) is the exploitation of similarities between adjacent frames in a video sequences, and is an essential part of the H.264 and other video compression standards. However, it introduces an increase of computation complexity resulting in longer execution time. In this paper, the search range for block-matching ME is made adaptive, based on the motion vectors present in preceding frames. The proposed algorithm determines the amount of motion in past frames and classifies the video sequence as having low, medium or high motion. This classification and the direction of the motion vectors, are used to dynamically adjust the search window size and general orientation. Simulation results show that execution time could be reduced by 42% - 60% with a small degradation in PSNR value, to that of non-adaptive ME.

Correction of Under-reaching in Twin circuit Parallel Overhead Lines without Residual Current input from the Parallel Line

Abstract: Mutual coupling poses one of the most difficult problems witnessed during single phase to earth fault, in transmission line protection. In lines, on multiple circuit towers or on the same right of way, the zero-sequence circuits of the lines get mutually coupled causing an error in the apparent impedance seen by the relay. This causes the distance protection relay at one end of the faulty line to over-reach while the one at the other end to under-reach. Also, incorrect sensing of the ground fault due to zero-sequence voltage inversion caused by mutual coupling in the zero-sequence network may lead to false trip of the neighbouring healthy line. This paper presents a non-iterative microprocessor based algorithm, not requiring residual current measurement from the parallel circuit, for computing fault distance and zero sequence compensation in basic distance relaying scheme.

Design of Harmonic Filter and Antenna Switch for Two-way Mobile Radio

Abstract: The design of a harmonic filter and an antenna switch for a two-way mobile radio system is reported here. The harmonic filter is a filter that makes sure that the higher order harmonics from the power amplifier stage are sufficiently attenuated so the transmitted signal is as pure as possible. Then an antenna switch must switch between transmitter and receiver in a half-duplex radio. In this work, the design of a harmonic filter and an antenna switch that meet the TIA specifications is reported. The ADS based design has been prototyped and tested. Some optimization has been performed to improve the radio performance.

Product-mix Design Decision under TOC by Soft-sensing of Level of Satisfaction using Modified Fuzzy-LP

Abstract: This chapter outlines an intelligent fuzzy linear programming (FLP) having a flexible logistic membership function (MF) in finding out fuzziness patterns at disparate level of satisfaction for theory of constraints-based (TOC) product-mix design problems. One objective of the present work is to find out degree of fuzziness of product-mix decisions having disparate level of satisfaction of decision-maker (DM). Another objective is to provide a robust, quantified monitor of the level of satisfaction of DMs and to calibrate these levels of satisfaction against DMs' expectations. Fuzzy-sensitivity of the decision has been focused for a bottle-neck-free, optimal product-mix solution of TOC problem.

Changes in the pushover analysis results of offshore jacket platforms due to the incorporation of the aging effect of piles

Abstract: The pushover analysis of jacket platforms in the past has revealed that most of the collapse failures occur due to the lack of strength of the pile foundation. However, when the jacket platforms which have been collapsed due to extreme conditions were looked into, it was found that most of them had their foundations intact. These contrasting facts can be explained with the help of the phenomenon called ‘aging of piles’. Aging effects of piles have been experimentally proven to improve the pile capacity with time, but due to lack of proper understanding and suitable techniques to incorporate them, these aging effects were ignored when the pushover analysis was done. In this study, a simple technique of stepping up of the soil curves in order to accommodate the increase in capacity of pile foundation due to aging is utilised. Three different jacket platforms are employed to study the changes to Reserve Strength Ratio after the pushover analysis incorporating piles’ aging effect. The adequacy of the new pushover analysis results in explaining the actual case scenarios are also discussed. The study has provided a deeper knowledge into the behaviour of aged offshore jacket platforms.

Design of Power Amplifier for a Two-way Mobile Radio

Abstract: The design and prototyping of a power amplifier for a two-way mobile radio is reported here. Mobile radios usually have transmitter whose power output ranges from 1 W to 50 W. Design of transmitter line-up for mobile radio involves the design of appropriate matching network for driver and power amplifier. The power and voltage control of these devices are equally important. Designing a mobile radio transmitter is regarded tricky due to difficulty in getting a robust transmitter that is stable with minimum oscillation. In this work, the design of a power amplifier with appropriate matching network for application in 216 MHz to 247 MHz is attempted using Advanced Design Simulator (ADS) and prototyped.