Computer Simulation of Current Forces on Motion of Floating Production Storage and Offloading in Irregular Waves

This paper presents the effect of current forces on the motion of forces on Floating Production Storage and Offloading (FPSO) in irregular waves. The objective of this research is to compute the motion of FPSO in irregular waves by time domain simulation including the effect of current forces. A study is made on the slowly varying oscillations of a moored single body system in a current and waves. Linear potential theory is used to describe the fluid motion, and three-dimensional source distribution techniques are applied to obtain the hydrodynamic forces and transfer function of the wave exciting forces. OCIMF (1994) data are used for estimation of the current forces. The non-linear time domain simulations have been carried out in irregular waves. Based on it, slowly varying motion responses are examined including the effect of the current forces. Several environmental conditions, such as the current angle of attack, current velocity, significant wave height and mean wave period are considered, which may significantly affect FPSO motion in surge, sway and yaw moments. It is found that the effect of current forces is quite significant when the current velocity is increased. In this simulation, while the current velocity is increased to 3.0 meter/seconds, the impact on FPSO motion is quite significant, which should be taken into consideration from the point of view of safety, failure of mooring systems, operating responses and the dynamic positioning of the FPSO

An innovative approach to heat extraction from a salinity gradient solar pond to enhance overall efficiency

A solar pond is a simple and low-cost solar collector with long-term thermal storage. It utilizes a large body of salinity gradient water to absorb radiation from the sun and stores it in the form of heat at the bottom of the pond with temperature between 70-90oC. The pond consists of three different layers. The cold thin upper layer is known as the upper convective zone (UCZ) and consists of low salinity water and has temperature close to the local average ambient temperature. The second layer is the gradient layer known as the non-convective zone (NCZ), where salinity increases from the top of the NCZ to the bottom of the NCZ. The bottom layer or lower convective zone (LCZ) has homogenous high salinity water which absorbs and stores solar thermal energy which reaches the bottom of the pond. Conventionally, heat has been successfully extracted from the LCZ. This study concerns an attempt to extract the absorbed heat from the NCZ using external heat exchangers with the aim of enhancing the overall efficiency of the solar pond. External heat exchangers were fabricated and installed to extract heat from different levels in the NCZ. The process used a 12V pump to withdraw hot brine from the NCZ and re-inject it to the same level. Cold brine from the UCZ was used as a cold heat transfer fluid to extract heat from each of the heat exchangers. The results show that by extracting heat from the NCZ, the thermal efficiency of a solar pond could potentially be improved to 50% as compared with the conventional heat extraction method from the LCZ only. An adverse effect associated with active heat extraction from the NCZ was the development of instability in the salinity gradient layer. Optimisation of the technique for withdrawal and re-injection of the cooled brine into the NCZ is essential to overcome this issue. It needs to be addressed as a future study. The other part of the present study was the investigation of a semi-passive thermosiphon heat extraction system for heat removal from the NCZ or LCZ of a solar pond. The thermosiphon heat extraction system relies on buoyancy effects to remove heat by the effect of temperature difference. Theoretical governing equations have been developed based on principles of conservation of energy and mass. Theoretical analysis revealed great potential for this system to be implemented in solar ponds. Experimental results from a single thermosiphon heat extraction system have been presented for various cooling water mass flow rates. The experimental and theoretical performance estimates were compared and the results showed a good agreement. The experimental findings showed that a thermosiphon heat exchanger has the potential to minimize the use of pumps in heat extraction from solar ponds

Gunung Tahan Trail: a historical review

There are still a lot of information on the history of Gunung Tahan Trail which remain unknown to the Malaysian public; some were buried with the demise of the elderly living around this mountain. This paper attempts to reveal the history of this famous trail which is located in Taman Negara in relation to the origin of its name, local belief and folklore of the mountain, colonial proposal for the establishment of grand hill station and early attempts to explore the mountain. Most of the data and information for this review were gathered from field notes and expedition reports published in various journals between 1880 and 1940. These information would be useful to Taman Negara Park Management in enriching recreational and nature tourism experiences among users of Gunung Tahan Trail

Augmented diffuser for horizontal axis marine current turbine

The potential of renewable energy sources is enormous as they can make a major contribution to the future of energy needs. The ocean has a great potential to become a practicaland predictable energy source compared to other energy resources such as solar, wind, and nuclear. It offers different sources of energy which can be utilized namely wave, tidal, offshore wind, thermal, and tidalcurrent. Among these sources, marine tidal current has major advantages such as higher power availability and predictability. The main objective of this research work is to design and develop a horizontal axis marine current turbine (HAMCT) that suitable for operating within Malaysian ocean, which has low speed current (0.5 – 1 m/s average). A prototype of augmented diffuser 4-bladed HAMCT applying NACA 0014 was proposed in the current study. The turbine model has 0.666 m diameter, and it was designed to produce as much as power from flowing water current. Model was constructed and tested at Marine Technology Center (MTC) in three conditions, namely, free tow testing, ducted tow testing, and ducted diffuser tow testing in order to predict the power and efficiency of the turbine system. The results showed that the application of duct was significant to concentrate the flow and diffuser arrangement was effective when it was placed behind of the rotor in this condition of low water current speed. The maximum efficiency Cp obtained in the current system was 0.58

Influence of retrogression and re-aging heat treatment to stress corrosion cracking resistance on Al-Zn-Mg-Cu alloy / Deraman R., Aziz M. R. And Y. Yaakob

The Al-Zn-Mg-Cu alloy is classified as a high strength to weight ratio material and is widely used in the aerospace structures. This alloy is susceptible to severe localized corrosion induced by heat treatment. The objective of this study is to elucidate alternative heat treatment techniques, which reduce the alloys susceptibility to Stress Corrosion Cracking (SCC). A series of different heat treatments have been performed in the Al-Zn-Mg-Cu alloy using cube shaped and C-ring specimens that had been T6- and T7-tempered and undergone Retrogression and Re-aging (RRA) heat treatments. The specimens were exposed to hardness testing, optical testing and immersion testing in a corrosive environment. The effectiveness of the heat treatments was evaluated with respect to improvements in corrosion resistance and the longevity of the Al-Zn-Mg-Cu alloy. The susceptibility of the Al-Zn-Mg-Cu alloy to SCC has been directly related to the precipitation of MgZn2 particles at the grain boundaries. Precipitation hardening of Al-Zn-Mg-Cu alloy increases the hardness of the material, but increases susceptibility to SCC failure. RRA treatment greatly improved the corrosion resistance and longevity of the alloy combined with minimal strength reduction

Rheological, chemical and DSC thermal characteristics of different types of palm oil/palm stearin-based shortenings

This study was carried out to evaluate the physical and chemical properties of different types of shortenings, formulated by mixing refined, bleached, and deodorized palm oil and palm stearin (PO:PS) in the following ratios: 100:0, 80:20, 60:40, 50:50, 40:60 and 20:80 and 0:100. The properties of experimental and commercial shortenings were investigated using four different analytical techniques, namely high performance liquid chromatography (HPLC), gas chromatography (GC), differential scanning calorimetry (DSC) and controlled stress rheometer. In addition, iodine value (IV) analysis was carried out. The results revealed that the prominent fatty acids in the products were palmitic (44.88-61.91%), oleic (26.24-39.14%) and linoleic (6.13-11.68%). At the same time, triacyglycerols (TAG), such as OOO, OOP and OOS, were found to decrease, while PPO increased due to the increase in the palm stearin content of the shortenings. Higher viscosity and more storage (G′) or loss (G″) modulus properties were noted in the experimental and commercial shortenings containing higher and lower concentrations of palm stearin and palm oil, respectively. Certain parameters such as the onset, peak and endset temperatures (ºC) were detected for both the melting and cooling data. However, increasing the palm stearin concentrations in the samples was shown to have caused increases in the endset temperature and peak height, and vice versa. Thus, chemical and physical properties of the formulated shortenings may influence the quality of baked products

ASSESSMENT OF THE ACOUSTICAL PERFORMANCE IN MALACCA MOSQUE,MALAYSIA: A CASE STUDY ON THE SAYYIDINA ABU BAKAR MOSQUE

As a building for worship and one of the important symbols in Islam, a mosque is usually designed with its architectural grandeur. Among of the characteristics is its spacious interior to create a perception so that people will feel ’small’ when entering the house of God. Most mosques therefore have high ceiling and are usually constructed with dome shape. In Malacca, Malaysia however, the architectural of the mosque resembles the traditional Malay house where the ceiling follows a pyramidal shape. This paper discusses the acoustical condition of the mosque in Malacca. The Sayyidina Abu Bakar Mosque is presented here for a case study. Measurement of its reverberation time was conducted and the results are validated with simulation data from CATT room acoustics software. Other important acoustical parameters are evaluated such as the early decay time, clarity, definition, lateral fraction and speech transmission index

CFD simulation of water gravitation vortex pool flow for mini hydropower plants

Mini hydropower plants can be expected to have a good potential to provide electricity to remote communities. An important part of this economic and clean energy system is the conversion of the low-head potential energy into kinetic energy to drive the power turbines. One way of converting the low-head potential energy is using a gravitation vortex pool. This paper describes work to optimize the vortex pool to improve energy conversion and hence generate electricity from low heads of between 0.7 m to 3 m. The commercial Computational Fluid Dynamics (CFD) code ANSYS Fluent was used in this study to investigate the optimum configuration of the vortex pool system. The free surface flow of this system was mathematically described. A parametric study was carried out using the software to determine the main parameters affecting the efficiency of the energy conversion. This parametric study utilized Fluent, which focused on the effect of changing water depth and outlet diameter on inlet/outlet speed; which is novel approach. The results from this study could help in the investigation of the optimum configuration of the vortex pool system

Potential use of Fourier transform infrared spectroscopy for differentiation of bovine and porcine gelatins

In order to classify unknown gelatin into their species of origin, a simple and rapid method for the qualitative determination was developed using Fourier transform infrared (FTIR) in combination with attenuated total reflectance (ATR) and discriminant analysis. The spectra were analysed using a chemometric method, principal component analysis (PCA), to classify and characterise gelatin compounds using regions of the FTIR spectra in the range of 3290–3280 cm−1 and 1660–1200 cm−1 as calibration models. Results from PCA, which were subsequently represented by the Cooman’s plot showed a clear distinction between gelatin samples of bovine and porcine origins. This qualitative approach, besides providing a rapid determination of the source of gelatin, may also be established based on a second derivative study of the FTIR spectrum to alleviate any doubt of the gelatin source for applications in the food and pharmaceutical industries

Influence Of MWCNTs Addition On Mechanical And Thermal Behavior Of Epoxy/Kenaf Multi-Scale Nanocomposite

This research was conducted to develop kenaf reinforced epoxy/MWCNTs multi-scale composite using kenaf fibre and MWCNTs as the reinforcement in epoxy as the hosted matrix. The composites were produced by using a combination of hand lay-up and vacuum bagging process. The selection of optimum composition of epoxy-MWCNTs is based on the MWCNTs loading and the resulted mixture viscosity. Lower resin viscosity is required to allow good wetting and interaction between matrix and filler, which will yielded superior final performance of the fabricated composites. Therefore, different loading of MWCNTs (0.0 wt. %, 0.5 wt. %, 1.0 wt. %, 3.0 wt. %, 5.0 wt. %, 7.0 wt. %) were used to investigate the mechanical and thermal properties of the composites. As a result, the epoxy/kenaf/MWCNTs multi-scale composite at 1.0 wt. % of MWCNTs addition had yielded substantial improvement by 15.54 % in tensile strength and 90.54 % in fracture toughness. Besides, the fracture surface morphology of the selected samples were analysed via scanning electron microscopy (SEM) observation to further support the reinforcement characteristic of epoxy/kenaf/MWCNTs multi-scale composite