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Ulasan: pembangunan teknologi penggasan dan penggunaan
No full textTeknologi penggasan berpotensi menghasilkan sumber tenaga bersih dan cekap. Teknologi ini berkeupayaan menghasilkan gas sintesis dari pada bahan mentah berasaskan karbon bernilai rendah atau negatif seperti arang batu, kok petroleum, minyak bahan api bersulfur tinggi, bahan buangan atau sisa dan biojisim. Gas yang dihasilkan daripada proses tersebut digunakan menggantikan gas asli, bertujuan menjana kuasa elektrik, atau sebagai bahan mentah asas untuk menghasilkan bahan kimia dan bahan api cecair. Penggasan merupakan proses yang menggunakan haba, tekanan, dan wap untuk mengubah bahan secara langsung menjadi gas, seperti gas karbon monoksida dan hidrogen. Teknologi penggasan mempunyai perbezaan dalam pelbagai aspek namun terdapat empat faktor kejuruteraan yang menjadi teras kepada sistem penggasan seperti reaktor penggasan atmosfera (tahap kandungan oksigen atau udara), pemanasan dalaman dan luaran, rekabentuk reaktor dan suhu operasi. Bahan mentah yang digunakan, disediakan dan dimasukkan dalam bentuk kering atau butiran kecil, ke ruang reaktor yang disebut sebagai penggas. Bahan mentah mengalami keadaan panas, tekanan serta persekitaran yang kaya atau rendah dengan kandungan oksigen di dalam penggasan. Terdapat tiga produk utama dari proses penggasan iaitu gas hidrokarbon (juga disebut singas), cecair hidro karbon (minyak) dan arang (karbon hitam dan abu). Singas dapat digunakan sebagai bahan api untuk menghasilkan tenaga elektrik atau wap, sebagai blok asas untuk pelbagai jenis bahan kimia. Apabila bercampur dengan udara, singas dapat digunakan dalam enjin petrol atau diesel dengan sedikit pengubahsuaian pada enjin
Bamboo residue as a potential activated carbon for removal of water pollutants: a commentary
No full textBamboo is one of the fastest-growing plants that exist on earth and can be found in many countries. Its application generally ranges across both the engineering and non-engineering sectors. Traditionally, bamboo is mainly used in the construction field, but recent trends and studies have also shown its potential in the water treatment industry as a low-cost adsorbent. Thus, this paper aims to highlight the recent studies on bamboo residue as a potential precursor for activated carbon as well as its performance in treating water pollutants. Apart from that, the current limitations, and suggestions on the further development of bamboo activated carbon, are also integrated to provide insight on its potential usage in the industrial process
Water-cement ratio on high-cycle fatigue in the theory of critical distances of plain concrete
No full textThe theory of critical distances (TCD) represents a new area of research on fatigue damage in concrete that is primarily used to characterise fatigue and fracture behaviours. Although TCD is accurate, it appears inconsistent when considering the water–cement ratio of concrete. Such inconsistency is related to the tendency to overlook the effects of the water–cement ratio owing to the small differences observed in tensile strength. The study’s main objective is to explore how sensitive fatigue characteristics in concrete are to different water–cement ratios. This research is important because information on concrete’s fatigue limits—especially regarding comparisons between different concrete mixes—is scarce. There is a lack of standard procedures for testing the fatigue and fracture behaviour of plain concrete, thus being inconsistent and slow. Thus, the current study has utilised the TCD concept to assess fatigue. However, TCD seems to be susceptible to changes in the water–cement ratio of concrete. Water–cement ratios of 0.3, 0.4, and 0.5 increased concrete’s fatigue limit to 2.883, 3.022, and 3.903 MPa, respectively. These increases were confirmed to be significant. Thus, this research will improve the current understanding of TCD’s value in fatigue analyses of concrete structures
Analytical solutions for fractional caputo-fabrizio casson nanofluid on riga plate with newtonian heating
No full textIntroduction of fractional derivatives to the mechanics of fluid flow is relatively new. Even though the exact geometrical representations of fractional derivatives on fluid mechanics have not been discovered, recent literatures have proven that it is a paradox that will be useful in the future. Meanwhile, Riga plates are actuators that is convenient for controlling the velocity of fluid flows. Widely used in the field of marine engineering, the properties of fluid flowing over Riga plates are worth investigating. Thus, the aim of this study is to investigate the analytical solutions of an unsteady incompressible Casson nanofluid flowing over a Riga plate with presence of Newtonian heating. Carboxymethyl Cellulose (CMC) water was used as a prime example of Casson fluid with Copper-Oxide (CuO) nanoparticles. Coupled with a non-Newtonian fluid, the Casson fluid, and the Caputo-Fabrizio fractional derivative, the analytical solutions obtained will be beneficial in the engineering world as a tool for validating experimental and numerical studies. Through this study, analytical solutions were obtained and the profiles of both velocity and temperature of fluid with variations in parameters were investigated. It is observed that variations in the fractional derivative parameter produces a spectrum of solutions that abides the initial and boundary conditions set. An amplification of the modified Hartmann number increases both the velocity and temperature profiles, while an amplification of the nanoparticle volume fraction decreases the velocity profile but increase the temperature profile
Microfluidic based impedance flow cytometry-dual microneedles for red blood cell detection
No full textThis thesis presents a microfluidic impedance flow cytometry-dual microneedle device for cell detection. Single-cell detection plays a significant role in biomedical diagnostics, such as early cancer cell detection and pathogenic bacteria cells in the blood. The growing need for simple and low-cost microfluidic device fabrication led to the invention of numerous microfluidic-based impedance flow cytometry (IFC) techniques. The current method for impedance flow cytometry technique is limited to an expensive and complex fabrication process of gold microelectrode. Therefore, the IFC-dual microneedle device with a simple design structure and uncomplicated fabrication process for cell detection is presented. The device utilized the two Tungsten microneedles with 25 |im of tip diameter, placed at the half-height of the microchannel as the measurement electrode. The design was characterized and optimized in terms of physical dimension, leakage conditions and sensitivity. The polystyrene (PS) microbeads with three different sizes (5 |im, 7 |im and 10 |im), yeast cells with different concentrations and red blood cells (RBC) were utilized to perform the cell detection of this IFC device. This IFC device was able to detect as low as 1 .2 x 1 04 cfu/mL cells of yeast cells in a solution medium. Moreover, the ratio of the impedance at high frequency vs. low frequency, known as opacity, was used to discriminate between the PS microbeads and RBC. In addition, the proposed device demonstrated that the specific membrane capacitance of an RBC is 9.42 mF/m- , with the regression coefficients, p at 0.9895. Measured results were found to lie in the comparable range with the previous technique (7-14.3 mF/m ). The presented IFC-dual microneedle device provides an opportunity for simple medical and food safety screening processes in developing countries
Comparison of diesel engine performance between a mechanical pump and a common rail fuel injection system equipped with real-time nonsurfactant emulsion fuel supply system
No full textThe global focus in emulsion fuels is due to the advantages over conventional diesel fuels. It has the capabilities to simultaneously reduce the emissions of NOx and smoke. It also said to reduce the fuel consumption of diesel engine by significant percentages. However, due to the interdependency on surfactant, emulsion fuel does not seem to be possible as alternative fuel in an economic perspective. This is because of the high market price of the commercial surfactant. Therefore, this research focused on non-surfactant W/D that produced by a system known as Real-Time Non-Surfactant Emulsion Fuel Supply System (RTES). RTES has been applied with the goal of investigating the impact on exhaust emissions and fuel consumption of a mechanical pump fuel injection system diesel vehicle (MP) and a common rail fuel injection system diesel vehicle (CR). A one-ton truck represents as MP (Mechanical Pump) and an SUV represent as CR (Common rail) are the test vehicles for the said research. The non-surfactant W/D with 6.5 wt.% of water produced by the RTES used as the test fuel and named as E6.5. It has been emulsified in the RTES right before being injected into the diesel vehicles. The testing was performed on a chassis dynamometer following the West Virginia University 5-peak cycles. The findings show that the utilization of non-surfactant W/D has increased the fuel consumption by 7.39% for MP and 3.2% for CR respectively as compared with base diesel fuel. NOx, smoke emissions and exhaust temperature have significantly reduced by the MP relative to CR vehicles. Overall, the concept of non-surfactant W/D seems to have implementation potential for reducing harmful emissions from both diesel-powered vehicles
Numerical analysis on the crosswind influence around a generic train moving on different bridge configurations
No full textIn this article, a numerical approach is applied to study the flow regimes surround a generic train model travelling on different bridge configurations under the influence of crosswind. The bridge is varies based on the different geometry of the bridge girder. The crosswind flow angle (Ψ) is varied from 0° to 90°. The incompressible flow around the train was resolved by utilizing the Reynolds-averaged Navier-Stokes (RANS) equations combined with the SST k-ω turbulence model. The Reynolds number used, based on the height of the train and the freestream velocity, is 3.7 × 105. In the results, it was found that variations of the crosswind flow angles produced different flow regimes. Two unique flow regimes appear, representing (i) slender body flow behaviour at a smaller range of Ψ (i.e. Ψ ≤ 45°) and (ii) bluff body flow behaviour at a higher range of Ψ (i.e. Ψ ≥ 60°). As the geometries of the bridge girder were varied, the bridge with the wedge girder showed the worst aerodynamic properties with both important aerodynamic loads (i.e. side force and rolling moment), followed by the triangular girder and the rectangular girder. This was due to the flow separation on the windward side and flow structure formation on the leeward side, both of which are majorly influenced by the flow that moved from the top and below of the bridge structures
The 4W framework of the online social community model for satisfying the unmet needs of older adults
Full text linkHuman's cherished and respectable desires could be fulfilled by social integration through interaction with their friends and families. These kinds of interactions are critical for the elderly, particularly for someone who has retired. Online social communities could assist them and offer a beneficial impact on the elderly. However, because the elderly people are hesitant to use new technology, researchers have attempted to integrate specially built social networking applications into simple user-interface gadgets for the elderly through the context aware systems. A proper understanding amongst the aged and the supporting community people is needed for optimal execution of the platform. The study presents a 4W framework (Who, What, Where, When) to effectively comprehend and portray the online social interaction community model's application in assisting the elderly in satisfying their unmet needs, as well as to improve the system's efficiency in addressing the elderly's unfulfilled demands. It is essential to discover what the users are keen on and provide a chance for the community group to take good decisions by utilizing the insights gained from these events
Guidelines for tracheal stent costumization and implantation
Full text linkOne of the treatments of tracheal stenosis is by stent implantation to reopen the constricted trachea lumen. However, post-stenting complications such as stent migration has been reported. This migration is due to undersized implanted stent. On the other hand, oversized implanted stent may pose excessive stress onto the wall of the trachea. Therefore, there is a need to customize the stent size according to the patients’ requirements. Thus, this thesis proposes a correlation of a customized stent that addresses the two problems mentioned. The analysis of a healthy trachea is performed and the effect of the different locations of the stenosis is investigated. Then, the effects of implantations of selected stents are numerically studied. The stents are also subjected to several mechanical testing for failure analysis. The results show that the developed stent is able to withstand various mechanical loads and deformation. The currently developed stent performed better than that of the commercial stent by at least 60 percent in bending test, 10 percent in radial compression test and 15 percent in torsional test. The stent is then tested at various tracheal stenosis locations. For a stenosed trachea, the location of the stenosis at the bottom part will pose the highest risk to breathing problems. Post-stenting results show that the developed stent is able to revert the flow inside the trachea to the original flow conditions. The flow rate distributions to the right bronchus were reduced by more than 30 percent as compared to flow rate distributions in healthy trachea. Finally, a correlation is proposed to enable stent customization that best fits patients’ requirements. This customized stent is predicted to be able to address the stent migration problem and excessive stress exerted to the trachea wall
Hull resistance and air-injected ballast free system performance for liquified natural gas ship
No full textBallast water discharge may introduce and transport unwanted marine organisms to the discharging area. The Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) considers ballast water hazardous due to possibly have a negative impact on the receiving ecosystems. Many researchers have investigated possible solutions for the management of ballast water to minimize the risks, including the ballast-free system. However, the application of the ballast-free system has created a new issue on the hull resistance. Many techniques have been developed in order to reduce the frictional resistance of ship navigation. The need to have an advanced Liquefied Natural Gas (LNG) ship with environmentally friendly and low fuel consumption has brought to the application of an LNG ship with an air-injection ballast-free system. This research aims to determine the effect of resistance on the LNG ship which has been fitted with ballast-free system and to evaluate how the air-injected pressured bubbles reduce ship resistance and improve the system performance. Firstly, the total hull resistance of the LNG model with a onesided system was determined by simulation using ANSYS CFX and validated by laboratory experiment. Secondly, the resistance of the two-sided system was generated using ANSYS CFX. The experiment and simulation were limited to Froude number Fr=0.17 to Fr=0.22 at the ballast draft. The total resistance in the model’s scale was extrapolated to the ship’s scale according to the International Towing Tank Conference (ITTC – 1957) equations. From the extrapolated result, the LNG hull with the ballastfree system has increased the total bare hull resistance by 7.58% and 23.71% for onesided and two-sided systems, respectively. The increment of resistance is due to the additional wetted surface area of the ballast tanks and pipes. Meanwhile, the 0.5 bar air injection shows the optimum resistance reduction compared to the other air injection pressures. The 0.5 bar air injection has reduced the total bare hull resistance by 20.17% and 24.67% for one-sided and two-sided systems, respectively. The reduction of resistance from the two systems is due to more area on the hull’s bottom surface has been surrounded by air bubbles. Thus, these findings can be a guideline for the estimation of power calculation and future improvement from the current works