Institutional Repository (UniKL IR) (Univ. Kuala Lumpur)
Not a member yet
17810 research outputs found
Sort by
PHOTODEGRADATION PATHWAY OF BISPHENOL S BY TITANIUM DIOXIDE UNDER UVA IRRADIATION
No full textPlastic pollution has emerged as a significant global challenge in recent years. It is estimated that 5-10% of the
worldwide plastic production ends up in the oceans annually1. In 2020, Malaysia’s plastic consumption amounted
to 148 thousand metric tons, with an annual per capita of 16.78 kg2. The “Malaysia Roadmap Towards Zero Single-
Use Plastics 2018-2030” was introduced as a three-phase national plan to eliminate single-use plastics3. However,
existing plastic waste can snowball into an environmental crisis, as plastic and microplastic waste release various
additives during fragmentation. Among these additives, Bisphenol S (BPS) has been identified as an emerging
pollutant with the potential to adversely affect humans and animals. Therefore, the removal of this analog from
wastewater is essential. This study evaluated the effectiveness of titanium dioxide (TiO2) in photodegrading BPS
in an aqueous solution under UVA light while elucidating the photodegradation pathways. Key photodegradation
parameters, including the initial pH of the solution, photocatalyst dosage, and illumination period, were optimized.
UV-visible spectrophotometer results showed that at an initial concentration of 5 mg/mL, complete photodegradation
of BPS occurred within 180 minutes under UVA exposure. Kinetic study showed that the photodegradation process
followed the Langmuir-Hinshelwood kinetic model, with a rate constant of 0.0133 min-1. High-performance liquid
chromatography (HPLC) analysis identified a single intermediate persisting in the solution after 180 minutes of
photodegradation. However, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis detected four
distinct photodegradation peaks and elucidated their formation pathways, revealing a complex degradation pathway.
Overall, this study provides valuable insights into the photocatalytic degradation of BPS using TiO2 under UVA
irradiation. HPLC and LC-MS/MS analyses confirmed that while BPS undergoes significant degradation under UVA
light in the presence of TiO2, its degradation products persist as intermediate in the solution
IMPACT OF EFFLUENT WASTE FROM MACHINING PROCESS ON THE ENVIRONMENT THROUGH WATER ANALYSIS.
No full textLarge quantities of ferrous block metals are used every day in various sectors of industry to make body parts for automotive, furniture, electrical and mechanical items. During the manufacturing stage, the block metals are subjected to some form of material removal processes either through turning, milling, grinding, or drilling operations to obtain the final product. Various forms of wastes are generated during the machining operations in the form of effluent waste, solid waste, atmospheric emission and energy emission. If these wastes are not recycled or treated properly before disposal, there is a possibility that it can cause a detrimental impact on the environment through water and soil pollution.
This research aims to determine the impact of the effluent waste from the machining process on the environment through water analysis. A fivefold study is carried out to determine the impact of the effluent waste on the water stream. The preliminary study consists of a Scenario Analysis where five scenarios of effluent waste are drawn out using substances such as used coolant, tramp oil, solvent, powdered chips and sludge which are commonly found in the effluent waste. The wastes are prepared according to the scenarios and are disposed through the IPROM storm water drain. Samples of effluent waste are collected at specific locations according to APHA method and are tested for the WQI parameters. Following this, a comparative study is conducted by collecting samples of the effluent waste from seven SME locations and from IPROM workshop to test the quality of effluent water. The samples are also tested for the presence of metals such as Nickel, Chromium, Zinc, Boron, Molybdenum, Ferum, Cadmium, Manganese and Selenium. The results obtained from the tests are compared with the Environmental Quality (Sewage and Industrial Effluents) Regulations, 1979 Standard B specification for the inland water body. The results obtained from the tests showed high values of Chemical Oxygen Demand, Ammoniacal Nitrogen and Total Suspended Solids. An Acute toxicology test was also conducted with live Minnows and juvenile Koi fishes according to United States Environmental Protection Agency, to determine the LCso of the effluent waste. Observations are made to study the behaviour of the fishes when it is in contact with the effluent waste. An Environmental Quality Tool is developed for the small and medium scale enterprises as a preventive control measure for the planning phase of the environmental management system to reduce the environmental impact due to machining waste
PERFORMANCE ANALYSIS OF FRANCIS PUMP-TURBINE RUNNER WITH ADJUSTABLE BLADE USING COMPUTATIONAL FLUID DYNAMICS
No full textOne of the most common energy storage system that is used for stabilising the grid is Pumped Hydroelectric Storage (PHES) system. Although PHES has been used for a long time, most of the existing PHES cannot vary the amount of electricity that they can store from the grid. This will cause a problem when the grid has a high penetration of wind and solar energy. There are few solutions that have been suggested, but all of them require additional big machine and space which make it not a practical solution for existing PHES power plant.
This research proposes a new mechanism that can be introduced to a Francis pump-turbine runner which can improve the operational flexibility of the machine when it is operating as a pump at PHES plant. The design started off from an existing turbine runner and some modifications were made to allow the blade tip to be adjusted, enabling the turbine to change the pump power whilst operating at a fixed rotational speed. All the research works are based on Computational Fluid Dynamics (CFD) simulation. Based on the research done,this mechanism does not affect significantly the efficiency of the runner in turbine mode and was able to vary the pump power ranging from -30.77% to 16.67% without cavitation. The round-trip efficiency obtained in this research was 78.33% - 78.62% which is comparable to the existing PHES power plant of 75%- 85%
LEAN MAINTENANCE FRAMEWORK FOR ARMY VEHICLES SERVICEABILITY
No full textServiceability refers to maintenance, repair activities and is imperative in all organizations. In the context of Military organizations, these maintenance activities encompass the maintenance of equipment, weapons, vehicles, electronic items and other equipment. In planning maintenance, the Malaysian Army needs to consider the supply of supporting hardware so that it can be deployed to any area to where the Armed forces are conveyed. In any case, execution is troublesome when the Malaysian armed force is confronted with the issue of having Type-B military vehicles that do not meet the mandatory 80% serviceability rate that is required in workshop brigade. Type-B military vehicles in military organizations include all vehicles including trailers are not functioned as armored vehicles but are used to carry passengers, all types weapons, bullets, equipments and as a cargo. Type-B military vehicles are divided into operational and non-operational functions. The objectives for this research are threefold: (i) to identify the extent to which Type-B military vehicles in Royal Electrical and Mechanical Engineering Corps (REME) workshops achieve the mandatory 80% state of readiness serviceability level (ii) to investigate the perceived factors that contribute to the level of serviceability of Type-B military vehicles in REME workshops and {iii) to plan and propose a lean maintenance approach that would augment the serviceability level of Type-B military vehicles in REME workshops.
The findings reveal that in the sample period of 2012 to 2015, the average serviceability level of 80% was only achieved in year 2012; yet for years 2013 till 2015, the mandatory serviceability levels were not achieved. Meanwhile, the perceived factors that contribute to the serviceability level are human factors, spare parts and financial factors, as shown from the results of a multiple regression analysis using SPSS.
The simulation approach employed a three stage system, involving three experiments. Results show that using the simulation approach, a serviceability level of 80% can be achieved. From the findings of this study, the researcher recommends that the mathematical model, conceptual model and optimization table be adapted to suit distinctive maintenance operations in military organizations. This is because these models are important to gauge and build serviceability in repair and maintenance activities and may be useful to top management as an indicator for future activities and for the improvement of serviceability levels of military equipment
SURFACE ROUGHNESS OPTIMIZATION IN MILLING OPERATION OF POLYURETHANE BLOCK
No full textThe polyurethane block also known as PB is widely used in the automotive industry to manufacture checking fixtures (CF's). This material has high machinability and a low hardness that ranges from 3 7 to 84 at the shore D hardness value. Acquiring the desired surface roughness for this material has always been a challenge for the manufacturing industry due to its high porosity, especially when it comes to machining of complex shapes. This study focuses on the optimization of the milling parameters for a radial profile on a CF for a car seat belt bracket. DoE is used to investigate the effect of the milling parameters on the PB. Five variables namely Feed rate, Depth of cut, Spindle speed, Step over and Plunge rate are considered for this experiment. Surface roughness tester is used to evaluate the surface finish whereas the composition of the PB is determined by Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). Through the preliminary experiment phase of this study, it is found that the surface roughness of the PB is severely affected when machined under a water based cooling medium instead of a dry condition. The most common chemical elements found in the Necuron 651 are carbon, silicon, oxygen and sodium. In addition to these, traces of other chemical elements were also detected but in negligible amount in all 16 work pieces. The step over was found to be the most significant milling parameter that influenced the surface quality of the PB. Finally, a set of optimized parameters is proposed to machine complex geometries of surfaces on PB (Necuron 651) that serves as a base material for manufacturing checking fixtures
DESIGN OPTIMISATION OF SAVONIUS WIND TURBINE OPERATING AT LOW SPEEDS USING CFDFOR WIND FARM APPLICATION
No full textThe low wind speed condition in Malaysia poses a great challenge for generation of useful energy via wind turbine applications. Even though the Savonius wind turbine is proven to be able to operate well at low wind speed conditions, the low power efficiency has hindered its potential of commercialisation. This research investigated the feasibility of generating power at wind speeds of below 6 mis using a commercial computational fluid dynamics (CFD) solver. A standalone Savonius wind turbine was optimised by considering its blade twist angle, overlap ratio, and end plates design. The numerical methodology was validated first against the published wind turbine data. Optimum numerical parameters were obtained via a sensitivity study. The turbine performance was measured based on the ratio of power predicted by the simulation to the theoretical power available. The standalone helical Savonius turbine with 90° twist achieved up to 0.128 of power efficiency about 45% higher than conventional S-shape Savonius turbine. To further increase the turbine power efficiency, the effects of multiple turbines in several configurations were also studied. CFD results show that a proper location of the downstream turbine can enhance the overall power generation. Factors such as the gap distance and turbine direction of rotation were evaluated. Several cases of oblique two-turbine, oblique three-turbine and cluster turbine were analysed. At this stage, the effect of the turbine gap distance and rotational coupling on turbine performance were observed. Positive flow interaction between turbines at 0. 5-Diameter and I-Diameter gap distance enhanced the co-rotating turbine performance by 10% and 5% respectively. Furthermore, the application of contrarotating downstream turbine shows better performance when placed on returning blade region of the upstream turbine. The turbine power efficiency improved by 2% at ]Diameter gap distance for oblique three turbines. The optimum oblique layout was used to design triangular cluster configuration of three turbines. The overall performance improved up to 9%. Thus, the oblique and cluster turbine configuration were extended to a wind farm layout comprising nine turbines in V-formation. The implementation of contra-rotating turbine in wind farm layout resulted power efficiency enhancement up 11 %. The flow interaction between the neighbouring turbine contributes into an improvement of driving torque on each turbine in the system, hence improved the overall turbine performance. As far as the wind farm performance is concerned, the wind power density of the V-formation yielded four to five times higher than nine isolated turbines. Therefore, the placement of the multiple wind turbines in an optimised V-formation layout is the best choice in terms of space utilisation in limited wind farm area and its overall power enhancement
