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Plastics have remained the material of choice, and after serving their intended purpose, a large proportion ends up in the environment where they persist for centuries. The packaging industry is the largest and growing consumer of synthetic plastics derived from fossil fuels. Food packaging plastics account for the bulk of plastic waste that are polluting the environment. Additionally, given the fact that petroleum reserves are finite and facing depletion, there is a need for the development of alternative materials that can serve the same purpose as conventional plastics. This paper reviews the function of packaging materials and highlights the future potential of the adoption of green materials. Biopolymers have emerged as promising green materials although they still have very low market uptake. Polylactic acid (PLA) has emerged as the most favoured bioplastic. However, it is limited by its high cost and some performance drawbacks. Blending with agricultural waste and natural fillers can result in green composites at low cost, low greenhouse gas emissions, and with improved performance for food packaging applications. The continent of Africa is proposed as a rich source of fibres and fillers that can be sustainably exploited to fabricate green composites in a bid to achieve a circular economy.

This paper presents the experimental and analytical investigation of four air-based bifacial photovoltaic thermal collectors. The experiments were performed on four bifacial PV panels with four different packing factors and four different configurations of air-based PVT collectors. A mathematical model was developed to evaluate the energy and exergy performance of the collectors. The four designs were studied in under the steady-state conditions. All four models of photovoltaic thermal collectors were fabricated and indoor experimental studies were conducted using the solar simulator. The double-path parallel flow design indicated the highest total energy efficiency of 51%–67%, and the single-path design indicated the lowest total energy efficiency of 28%–49%, at a 0.7 packing factor. The single-path collector design is the best option if electrical energy is the dominant desired output energy. However, double-path parallel flow design is the best option if the thermal energy is the dominant desired output energy. In addition, the single-path design had the highest exergy efficiency (8.2%–8.4%) followed by double-path parallel flow design (7.2%–8%).

Over the years, the world was not paying strict attention to the impact of rapid growth in plastic use. This has led to unprecedented amounts of mixed types of plastic waste entering the environment unmanaged. Packaging plastics account for half of the global total plastic waste. This paper seeks to give an overview of the use, disposal, and regulation of food packaging plastics. Demand for food packaging is on the rise as a result of increasing global demand for food due to population growth. Most of the food packaging are used on-the-go and are single use plastics that are disposed of within a short space of time. The bulk of this plastic waste has found its way into the environment contaminating land, water and the food chain. The food industry is encouraged to reduce, reuse and recycle packaging materials. A wholistic approach to waste management will need to involve all stakeholders working to achieve a circular economy. A robust approach to prevent pollution today rather than handling the waste in the future should be adopted especially in Africa where there is high population growth.

The effects of hybridization between woven mengkuang fiber/woven silk on mode II delamination (GIIC) of laminated composites were investigated by performing the end-notched flexure (ENF) test. Various configurations of woven mengkuang/woven silk layers were considered. The composite samples were prepared using hand lay-up, along with the cold press method. After fabrication, the test specimens were subjected to end-notch flexure testing for mode II delamination based on ASTM D790-03. During the test, the crack propagation was observed; the sudden drop in load meant that the sample experienced crack growth. The configuration of woven silk in between the pre-crack provided an excellent improvement in GIIC. Further addition of woven silk layers for similar configuration also yielded significant improvements in the GIIC result. The rate of critical strain energy release increases with an increase in number of woven silk layers for the configuration of silk in between the pre-crack. The scanning electronic microscopy (SEM) result shows the cross-section of the samples. The study also demonstrated that surface interaction between woven silk/epoxy/woven silk was better than woven mengkuang/epoxy/woven mengkuang lamination.

This study investigated the energy absorption response and load carrying capability of woven natural silk/epoxy–triggered composite rectangular tubes subjected to an axial quasi-static crushing test. The rectangular composite tubes were prepared by hand lay-up technique. The tubes consisted of 12, 24, and 30 layers of natural woven silk/epoxy laminate and were 50, 80, and 120 mm long. The crashworthiness of the tubes was evaluated by measuring the specific energy absorption in quasi-static axial compression. Specific energy absorption was obtained from the load–displacement curve during testing. The failure mode of the tubes was analyzed from high resolution photographs obtained. Overall, the tube with 50 mm length and 30 layers showed the best crashworthiness among the tubes. The failure morphology showed that the specimens failed in two distinct modes: local and mid-length buckling. The triggered composite tubes exhibited progressive failure.

In this study, lamination panels were fabricated using chopped strand mat (CSM) and woven roving fabric (WR) as reinforcement for two different types of specimens, type Eb and type Pb, respectively. By a combination of plain materials composite lamination structures were formed, with [CSM/0/90/CSM]2s as an orientation layer for the structures. In this research study, the structural panel was produced by hand lay-up technique with a combination of unsaturated epoxy and polyester resin, separately. Therefore, with this publication, a characteristic combination of chopped strand mat/woven roving fabric, are presented. The experimental work for both types of specimens were performed by bending until the structure fails. The characteristics of different materials, i. e. the chemicals used and the composite lamination structure, were studied, because there are different types of damages in the structure of composite materials, such as delamination, matrix cracking, fiber-matrix damage and fiber pull-out. Furthermore, it can affect the behavior of composite materials in the whole structure. As a result, this process contributes to failure prevention, as the capabilities of the structures are known, before it can be used for any part, component or area. It was also shown that different configuration lamination layers influence the strength properties of the composite materials.

Various noise-absorbing materials and apparatus were developed not only for industry purposes but also for increased personal convenience through the absorption of unwanted sound. Absorbing products are typically passive mediums, whereas active-control absorption is expensive and complicated to install. Thus, in this study, a semi-active panel design for the sound absorber is developed to ensure operation at a required absorption level for a particular environment and to allow manual control. This study focused on producing an optimum design from several blueprints by using the simulation program, WinFlag. Simulation results are validated by using the impedance tube method. The samples used are perforated plates with open areas of 5%, 7.5%, 10%, 12.5%, ​​and 15%. The second layer is a 35-mm thick coconut coir fiber as the main absorbing material. The third layer is air cavity. Simulation results indicate that the panel with perforation plates with 15% open areas gained the highest peak of sound absorption coefficient (0.851) at 5000 Hz. By using 30 mm thick air cavities, the highest peak is 0.963 at 3129 Hz. Experimental results indicate that the highest peak of sound absorption coefficient is 0.847 for the 15% open area of perforated plates, whereas the highest peak is 0.934 when 30 mm thick air cavities are used. The same pattern in the overall results denotes that the experiment result agrees with that of the simulation

Noise pollution is a workplace hazard which causes loss of hearing, depending on the sound pressure level and duration of exposure. Because duration of exposure is usually uncontrollable, sound absorbers are used to reduce the value of sound pressure level. A common method to reduce noise is to use porous sound absorbers made out of mineral wools or glass fibres. However, these materials pose health risks and are non-recyclable. This project aimed to fabricate a sound absorber using recycled paper which is in the form of egg cartons as an alternative to the abovementioned fibres. Paper fibres posses high fibre porosity and can be manufactured in a manner which the properties can be easily controlled, making them ideal to be made into sound absorbers. Furthermore, they are biodegradable, do not pose health risks and can be manufactured into different shapes easily. Recycled paper was first turned into pulp, blended and poured into moulds. Different amounts of pulp was compressed until the sample size was approximately 20 mm thick and then dried in a furnace dryer at 600C for 12 hours. The samples were tested using a two-microphone, transfer function impedance tubes according to the ISO 10534-2 standard. Its porosity was determined using a modified wash basin method. The results indicate that the optimum panel has an average noise reduction coefficient, (NRC) of 0.50, which qualifies it to be used as a sound absorbing material. It also encounters its maximum value of 0.98 which occurred at the 1575-1675 Hz range. When compared to other materials, recycled paper has similar properties as coir fibre and is quite comparable to other commercial sound absorbers at the same thickness.

Thermoelectric cogeneration may be applied to the exhaust of an automobile to generate additional electric power, by applying a temperature differential across the thermoelectric power generation modules. To obtain maximum net power, the highest allowable temperature difference should be obtained. Therefore, a cooling system should be employed to ensure that the cold side of the thermoelectric modules remain as cold as possible. An evaporative cooling system patented by Einstein and Szilard is used as a base for a non-parasitic cooling system to be used together with thermoelectric modules. The cooling system utilizes the same heat which powers the thermoelectric modules as a power source. By utilizing the high solubility of ammonia in water, the solubility dependency with temperature, and usage of polar and non-polar solvents to direct the flow of ammonia as a coolant, it is possible to create a cooling system which performs better than passive heat sinks, but negates the power requirements of active cooling systems.

An experimental study on the effect of panel density on the sound absorption properties of a date palm fiber panel has been presented in this paper. The experiments were carried out by using impedance tube at the Acoustic Lab, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. The date palm fiber was tested for densities of 77 kg/m3, 100 kg/m3 and 125 kg/m3.The results show that the values of absorption coefficient improve when increasing the density of the panel. Noise reduction coefficient (NRC) was computed to compare the performance of the palm date fiber samples for the different densities. The NRC increases by increasing the density.

This paper presents the investigation of the characteristic behaviour of polymer matrix composites under Charpy impact conditions with different design configurations of the laminate structure. The aim of this study was to evaluate the capability of different lamination designs for composite materials, in term of contact load, energy absorption, deflection and damage behaviour. In this study, laminated panels were fabricated using chopped strand mat (CSM), woven roving fabric (WR) and foam-PVC Klegecell as reinforcement with a combination of epoxy or polyester resin, respectively. Structural panels of composite laminates were produced using a hand lay-up technique. Each configuration design was impact tested to failure. Finite element analyses (FEA) were employed in this study to correlate the experimental value of energy absorption with simulation results. The characteristics of different reinforcement types, matrix type, hybrid type, architecture and orientation type were studied. These characteristics need to be considered, due to their affecting the characteristic behaviour of the composite lamination structures. Based on the results, it was found that differences in configuration design of the lamination structure of the polymer matrix composites do influence the strength and weakness of the materials.

Pulsating twin jets mechanism (PTJM) was developed in the present work to study the effect of pulsating twin jets mixing region on the enhancement of heat transfer. Controllable characteristics twin pulsed jets were the main objective of our design. The variable nozzle-nozzle distance was considered to study the effect of two jets interaction at the mixing region. Also, the phase change between the frequencies of twin jets was taken into account to develop PTJM. All of these factors in addition to the ability of producing high velocity pulsed jet led to more appropriate design for a comprehensive study of multijet impingement heat transfer problems. The performance of PTJM was verified by measuring the pulse profile at frequency of 20 Hz, where equal velocity peak of around 64 m/s for both jets was obtained. Moreover, the jet velocity profile at different pulsation frequencies was tested to verify system performance, so the results revealed reasonable velocity profile configuration. Furthermore, the effect of pulsation frequency on surface temperature of flat hot plate in the midpoint between twin jets was studied experimentally. Noticeable enhancement in heat transfer was obtained with the increasing of pulsation frequency.

In the current study, the quasi-static compression test over natural silk epoxy composite tubes was performed using two different trigger mechanisms. The natural silk epoxy composite tubes used in this study consisted of 12 layers of woven natural silk as reinforcement and a thermoset epoxy resin as matrix. The natural silk epoxy composite tubes had lengths of 50 mm, and they were associated with external triggers, including four steel pieces located on the downside flat plate fixture and a plug trigger. The failure modes of the natural silk epoxy composite tubes were investigated using representative photographs taken during the quasi-static compression test. In addition to the load-displacement graphs, the crashworthiness characteristics of the natural silk epoxy composite tubes were exported. The results showed that the four-piece trigger mechanism changed the manner in which failure progressed i.e. from catastrophic to progressive. Plug trigger caused a significant reduction in load carrying capacity and energy absorption capability of specimens. The four-piece trigger retained energy absorption capability of specimens similar to the non-triggered ones, while both the reduction of peak load and increase in crash efficiency of these were observed to be significant.

Pulsed air jet impingement heat transfer is one of the most important area of heat transfer studies due to its wide engineering applications in heating and cooling such as in textile drying and electronics cooling. In this paper, the tests parameters used are a constant Reynolds number of 16000, copper impingement plate surface temperature of 100C, radial distance to nozzle outlet diameter ratio (r/d) in the range of 0 and 6 and different pulse frequencies between 0 Hz and 60 Hz. The nozzles have duty cycles of 0.18, 0.27, 0.31 and 0.35, the cylindrical pulse mechanism shape with four different circular areas of 314.16, 514.16, 614.16, and 714.16 mm and two different nozzle diameters of 15 and 20 mm are used. The objectives of this paper are to determine the effect of pulse shape and the nozzle diameter towards the heat transfer enhancement. Results obtained show that for nozzle with diameter of 20 mm (pulse shape 4), the maximum heat transfer rate is recorded at plate distance to nozzle outlet ratio (z/d) equals to 4 and for 15 mm nozzle diameter (pulse shape 1), the maximum heat transfer rate is recorded at z/d equals to 2. Optimum frequency is between 30 Hz and 50 Hz while highest heat transfer enhancement is between z/d of 2 and 4.

Silicon wafer accounts for almost one-half the cost of a photovoltaic (PV) panel. A bifacial silicon solar cell is attractive due to its potential of enhancing power generation from the same silicon wafer in comparison with a conventional monofacial solar cell. The bifacial PV cell is able to capture solar radiation by back surface. This ability requires a suitable reflector appropriately oriented and separated from the cell’s rear surface. In order to optimize the bifacial solar cell performance with respect to an external back surface reflector, diffuse and semimirror reflectors were investigated at various angles and separations from the back surface. A simple bifacial solar panel, consisting of four monocrystalline Si solar cells, was designed and built. Reflection from the rear surface was provided by an extended semimirror and a white-painted diffuse reflector. Maximum power generation was observed at 30° with respect to ground for the semimirror reflector and 10° for diffuse reflector at an optimized reflector-panel separation of 115 mm. Output power enhancement of 20% and 15% from semimirror and diffuse reflectors, respectively, were observed. This loss from diffuse reflector is attributed to scattering of light beyond the rear surface capture cross-section of the bifacial solar panel.

This manuscript contains the development stages of a multi-purpose wind tunnel built at the Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. The fully automated wind tunnel is named Pangkor after an island in Perak, Malaysia. The development of the wind tunnel consists of three stages namely the design, fabrication and testing & commissioning. The computational fluids dynamic (CFD) approach was employed to ascertain the main geometries to optimize space utilization. Calculations are made based on typical wind tunnel design guidelines. Pitot tubes-pressure transducer, hotwire anemometry, temperature, room humidity and barometric sensors were used to verify actual flow of our construction. A traverse installed at the wind tunnel is capable of a two dimensional movements. The 15 kW axial fan used is especially selected because of space limitation. A variable frequency drive (VFD) connected to fan’s motor allows velocity control from a computer. All devices are connected a computer with one single controlling software; Scilab – ensuring ease of operation. The project shows that, with a limited budget, a wind tunnel with full functionalities could be constructed

Bloom's Taxonomy is a classification of learning objectives within education that educators set for students. The cognitive domain within this taxonomy is designed to verify a student's cognitive level during a written examination. Educators may sometimes face the challenge in analysing whether their examination questions comply within the requirements of the Bloom’s taxonomy at different cognitive levels. This paper proposes an automated analysis of the exam questions to determine the appropriate category based on this taxonomy. This rule-based approach applies Natural Language Processing (NLP) techniques to identify important keywords and verbs, which may assist in the identification of the category of a question. This work focuses on the computer programming subject domain. At present, a set of 100 questions (70 training set and 30 test set) is used in the research. Preliminary results indicate that the rules may successfully assist in the identification of the Bloom’s taxonomy category correctly in the exam questions. © 2011 Published by Elsevier Ltd. Selection and/or peer reviewed under responsibility of the UKM Teaching and Learning Congress 2011.

Problem statement: Thermal comfort has a great influence on the productivity and satisfaction of indoor building occupants. The exposure to excessive heat during work may cause discomfort and contributed to low productivity among workers. Malaysia known with its hot and humid weather where in most of the survey study published indicated that workers in Malaysia automotive industries had exposed to excessive temperature while working. The study investigated the thermal comfort level experienced by workers at Malaysian automotive industry. Approach: The study had been conducted at one automotive parts assembly factory in Malaysia. The human subjects for the study constitute operators at tire receiving section of the factory. The environment examined was the relative humidity (%), WBGT, air temperature and radiant temperature (°C) of the surrounding workstation area. The environmental factors were measured using Babuc apparatus, which is capable to measure simultaneously those mentioned environmental factors. The time series data of fluctuating level of factors were plotted to identify the significant changes of factors. Then thermal comfort of the workers was assessed by using ASHRAE thermal sensation scale by using Predicted Mean Vote (PMV). Further Predicted Percentage Dissatisfied (PPD) was used to estimate the thermal comfort satisfaction of the occupant. Finally the PPD versus PMV were plotted to present the thermal comfort scenario of workers involved in related workstation. Results: The trend of relative humidity curve from the graph also indicated the increasing level of discomfort. The radiant temperature observed seems consistent during the study while there was decreasing of WBGT start from afternoon due to the rain. The study revealed that the PPD value of 54% of the workers population at the workstation are likely to be satisfied with thermal comfort at this station while the PMV index from ASHRAE indicated the value 1.07-1.41. Conclusion: The empirical study from the PPD and PMV index indicated that workers working at this were influenced by the heat. The less of PPD value from 80% of the population satisfied with the thermal comfort showed the environment factors that were not good for worker while the PMV index showed the area of work is slightly warm.

Recently, natural fibers become an attractive to automotive industry as an alternative reinforcement for glass fiber reinforced thermoplastics. Additionally, natural fiber components in the automotive industry can provide numerous advantages compared to synthetic conventional such as reduction of weight and cost, recyclability, renewability and in addition to eco-efficiency. Thus, the use of natural fibers in automotive industry has shown increasingly stringent environmental criteria. Furthermore, amongst grouped bast fibers such as flax, hemp, jute, ramie and kenaf; kenaf fiber seen as potential natural fiber with robust mechanical properties. Kenaf fiber had been explored to enhance desired mechanical properties as an automotive structural components. As usual, natural fibres have some issues and disadvantages when used as reinforcements for polymeric composites. Therefore, some modification performed on fibers such as chemical treatment was carried out. In addition, the use of a coupling agent and a plasticizer can also increase fiber-matrix adhesive bonding.

Thermoelectric modules are a useful way to extract waste energy from a readily available low quality heat source. However, the voltage generated by these modules varies with the temperature difference across its surfaces which are prone to fluctuations. Furthermore, the amount of voltage generated by individual modules is low. This can be rectified using voltage converters to stabilise the output voltage at the expense of some efficiency. In the case where a minimal number of modules are being used, a boost converter can be used to increase the input voltage from the thermoelectric modules to a higher level. Our previous study showed the results of the boost conversion process for multiple temperature differences, resulting in multiple input voltages and currents and found that the conversion efficiency increases with increasing input voltage at an almost constant input current. In this paper, we compare the experimental results for conversion efficiency against the expected values provided by the manufacturer, and find that when the input voltage is closer to the desired output voltage, the conversion efficiency increases.

Md. Ayub, Mohammad Hosseini Fouladi, Masomeh Ghassem, Mohd Jailani Mohd Nor, Hamidreza Soheili Najafabadi, Nowshad Amin and Rozli Zulkifli

In this world of advanced technology, many global organizations are realizing that the importance of their worker’s comfort level towards their performance in order to be competitive. The studies in thermal comfort allow enhancing the understanding the importance of working environment among workers and occupants from various fields. This paper is focuses on reviews of the recent studies on thermal comfort assessments at the industries in Malaysia. The findings from other researchers’ thermal comfort assessments at worldwide also reviewed together. This review would help the researchers, academicians and practitioners to take a closer look on how environmental factors affect human performance in industries and help to enhance the awareness on human comfort among all Malaysians.

This paper examines the first and second law efficiency of bifacial photovoltaic thermal (PVT) solar collectors. A mathematical model was developed to evaluate the system performance. Four air-based bifacial photovoltaic thermal panels were also designed based on the bifacial PV cell requirement. Most of the existing PVT designs contain an absorber plate, which in this research is replaced by a reflector to avoid blocking the rear aperture of bifacial cells. The following four air-based panel configurations were considered: single-path; double-path, parallel; double-path, counter flow; and double-path, returning flow. All four panel designs evaluated based on the first law and second law of thermodynamic, at steady state mode. Energy and exergy efficiencies of aforementioned designs strongly depend on packing factor and air mass flow rate. From an energy point of view (first law), the bifacial photovoltaic thermal panel with two parallel air streams exhibited the best efficiency (51%–67%) compared with that of the other three models. However, the exergy analysis indicated that a single air stream panel is preferable with 4.43%–10.15% exergy efficiency. The single-path panel design is the best option if electrical energy is the dominant desired output energy. But double-path parallel design is the best option if thermal energy is the dominant desired output energy.