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In ship motion stability, generally, capsizing occurs due to the following effects: loss in directional control such as in broaching-to; loss in stability (pure loss of stability) and transient effect like parametric excitation. It is generally accepted that hydrodynamic forces due to waves are dominant that cause vessels' capsizing. It is generally accepted that numerical simulation using computers are reliable to study the ship motions. As a result, the 6 degrees-of-freedom time domain simulation will be used to study the ship motions especially the large amplitude motions. In this paper, we adopt three classes of numerical approach namely explicit Runge-Kutta, implicit Runge-Kutta and Rosenbrock-type Runge-Kutta methods in order to verify the effect of stiffness in ship motion simulation.
Purpose – The purpose of this paper is to study the unsteady boundary layer flow of a micropolar fluid past a circular cylinder which is started impulsively from rest. Design/methodology/approach – The nonlinear partial differential equations consisting of three independent variables are solved numerically using the 3D Keller-box method. Findings – Numerical solutions for the velocity profiles, wall skin friction and microrotation profiles are obtained and presented for various values of time t and material parameter K with the boundary condition for microrotation n=0 (strong concentration of microelements) and n=1/2 (weak concentration of microelements). The results are presented along the points on the cylinder surface, starting from the forward to the rear stagnation point, for small time up to the time when the bounda...
The performance of the Box-Jenkins methods is compared with that of the neural networks in forecasting time series. Five time series of different complexities are built using back propagation neural networks were compared with the standard Box-Jenkins model. It is found that for time series with seasonal pattern, both methods produced comparable results. However, for series with irregular pattern, the Box-Jenkins outperformed the neural networks model. Results also show that neural networks are robust, provide good long-term forecasting, and represent a promising alternative method for forecasting.
A nonparametric kernel methods is proposed and evaluated performance for estimating annual maximum stream flow quantiles. The bandwidth of the estimator is estimated by using an optimal technique and a cross-validation technique. Results obtained from a limited amount of real data from Malaysia show that quantiles estimated by nonparametric method using these techniques have small root mean square error and root mean absolute error. Based on correlation coefficient test shown that the nonparametric model approach is accurate, uniform and flexible alternatives to parametric models for flood frequency analysis.
Due to high cost of data acquisition card in the market, this research concentrates on developing a high speed, low cost microprocessor and Ethernet controller based data acquisition for optical tomography system. Microprocessor is the main core to control the sensor circuitry while the Ethernet controller has the responsibility of transmitting data to PC and thus insuring the reliability of data. The data transfer rate will be up to Megabit per second (Mbps). In this optical tomography system, a projection geometry combining two orthogonal and two rectilinear in one layer is modeled.
Biofuel is known as a potential replacement of fossil fuel nowadays. In Malaysia, one of the simplest ways to produce Biodiesel is mainly by blending palm oil together with conventional diesel fuel (CDF). The performance study of the Biodiesel is essential in order to justify that Biodiesel is better than CDF as fuel. The temperature profiles along the combustor have been studied in this research. The reduction of exhaust pollutants is also studied by using gas emission analysis of Biodiesel. The objective of this study is to determine the optimum blend for best performance while producing less emission compared to CDF; and also to investigate the flame pattern of the blend. The results show that Biodiesel blend of B5 perform better at stoichiometric mixture and that all the emissions of Biodiesel blends are lower than that for CDF.
The system developed in this research has the objective of measuring mass flow rate in an online mode. If a single computer is used as data processing unit, a longer time is needed to produce a measurement result. In the research carried out by previous researcher shows about 11.2 seconds is needed to obtain one mass flow rate result in the offline mode (using offline data). This insufficient real-time result will cause problems in a feedback control process when applying the system on industrial plants. To increase the refreshing rate of the measurement result, an investigation on a data distribution system is performed to replace the existing data processing unit.
The corrosion potential of AISI 304 stainless steel coupons influenced by sulphate-reducing bacteria (SRB) has been studied. Pure colony of SRB was isolated from the Malaysia Marine and Heavy Engineering, Pasir Gudang, Johor. Open circuit potential measurements were carried out in variable types of culturing solutions with SRB1, SRB2, combination of SRB1 & SRB2 and without SRBs inoculated. The results showed that the corrosion potential, Eoc increased in the presence of SRBs (in pure and mixed culture) compared to that of control. EDS analysis showed the strong peak of sulphur in coupon containing SRB cultures compared to the control. Environment Scanning Electron Microscope (ESEM) data showed that the high density cell of SRBs were associated with corroding sections of surface steel comparing with non-corroding sections for coup...
Skidding is one of the major contributions to road accidents during wet weather condition. Therefore, a study is conducted to investigate the factors affecting Pendulum Test Value on Asphaltic Concrete surfaces. The main objective of this study is to determine the mix type and the crossfall percentage that best resist skid during wet weather condition. Three different types of dense graded mixes were used in this study which are AC10, AC14 and AC20. Those three mixes are tested using Sand Patch Test (SPT) and are then subjected to various rainfall conditions and crossfall percentages using Rainfall Simulator. The rainfall conditions are categorized as low rainfall, medium rainfall and high rainfall while the crossfalls were increased 2% from 0% to 10% crossfalls. During the event of rainfall on each mix surfaces, a Portable Skid Resist...
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