Journal Articles

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https://hdl.handle.net/20.500.14170/296

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  • Publication
    A BIM-based model checking in the green building maintenance: a review
    (Emerald Publishing, 2023)
    Zul-Atfi Ismail
    Purpose: This paper aims to identify the different system approach using building information modelling (BIM) technology that is equipped with automated evaluation processes. BIM research has mainly focused on theoretical models of acceptance in the green building (GB) maintenance industry. However, BIM has the potential to the competency’s performance and design knowledge of building control instrument. Realising this potential requires a study of BIM at the maintenance planning level, which is considered to be BIM-based model checking (BMC). BMC and its effect in the maintenance planning have not been sufficiently investigated. Design/methodology/approach: The aim of this paper is to present a critical review of literature on the theoretical background of BMC practices and the main features of information and communication technology tools and techniques in the GB maintenance projects. Findings: A theoretical framework of BMC is developed and presented. The proposed model incorporates requirement for maintaining a competency’s performance on maintenance planning schemes of GB projects and the importance of early integration of BMC in the design phase to identify alternative methods to cogenerate, monitor and optimise BMC. Originality/value: It is found that variables facilitating BMC are integrated at different GB maintenance environments levels and are shaped by the context. Directions for future research are presented.
  • Publication
    A critical study of the existing issues in circular economy practices during movement control order: can BIM fill the gap?
    (Emerald, 2022)
    Zul-Atfi Ismail
    The improper evaluation and information management of circular economy (CE) (i.e. design, planning, supply chain, waste pile and material hazard) is critical for public health and is a major problem in the waste management of precast concrete (PC) building manufacture and construction and demolition wastes industry. The CE model is particularly problematic for PC building construction projects where the standard practices for the total number of waste building materials are not appropriate and do not match the safe disposal design specification, such as the recent number increase in the Malaysian illegal construction waste pile during the Movement Control Order (11 March 2021, about 5 out of 29 landfills related to states enforcing Act 672). The study aims to develop a framework application (i.e. Building Information Modelling [BIM]) that supports intelligent waste recycling management and sophisticated CE model system solutions. Design/methodology/approach: Thus, the development of a new BIM-based programming algorithm approach is proposed for optimising CE in accordance with the needs of the current PC building construction schemes. As a precursor to this study, the concepts of CE practices are reviewed and the main features of BIM tools and techniques currently being employed on such projects are presented. Findings: Sophisticated CE system solutions are described as an essential component of this optimisation to reduce the amount of waste generated at the end of the life cycle of PC building construction projects and to better manage the resources used throughout it. Originality/value: Finally, the potential for a research framework for developing such a system in the future is presented.
  • Publication
    A hydrosuction siphon system to remove particles using fan blades
    (MDPI, 2023-01)
    Mohammed Hamid Rasool
    ;
    Mohd Remy Rozainy Mohd Arif Zainol
    ;
    Norazian Mohamed Noor
    ;
    Mohd Sharizal Abdul Aziz
    ;
    Mohd Hafiz Zawawi
    ;
    Muhammad Khairi A. Wahab
    ;
    Mohd Azmeer Abu Bakar
    Sedimentation in dam reservoirs can cause problems that lead to loss of storage capacity and decrease in the flood control volume. Hydrosuction sediment removal is one of the methods used to remove sediments from within a reservoir using the suction energy provided by the effective head. In this study, a new tool has been developed by attaching the reservoir to a suction pipe intake point and using a simple fan blade mechanism for the hydrosuction sediment removal system. This mechanism is used to create a vortex flow to suspend the settled particles. This paper investigated the effects of the fan blade angles, effective head, and inlet height from the surface of layer particles on the performance and efficiency of fan blades hydrosuction sediment removal (FBHSSR) and hydrosuction sediment removal (HSSR) systems based on the geometric scour hole parameters. Results from the experimental tests indicated the effectiveness of the FBHSSR system, with the fan blade angles of 30°, 45°, and 60° leading to approximately 800%, 200%, and 117%, respectively, removed particles greater than those of the HSSR system. Furthermore, the maximum depth and diameter of the scour hole were increased by 206%, 200%, and 137% and 135, 112%, and 117%, respectively, for each angle. The effective head or experiment time also enhanced system performance by increasing the suction discharge, but no change was observed in terms of efficiency. The critical inlet heights for the FBHSSR and HSSR systems are 1 time and 2.54 times, respectively, more than the diameter of the suction pipe. Thus, it can be concluded that using fan blades in HSSR systems is a good approach to improve the properties of the scour hole.
  • Publication
    A Properties of Municipal Solid Waste Incineration Fly Ash (IFA) And Cement Used in The Manufacturing of New Inventive Blended Cement
    ( 2022-01-01)
    Norlia Mohamad Ibrahim
    ;
    Roshazita Che Amat
    ;
    Nur Liza Rahim
    ;
    Izzatul Nurain Che Sang Beri
    ;
    Syakirah Afiza Mohammed
    ;
    Zailani W.W.A.
    Municipal solid waste incinerator fly (IFA) ash is prone to accumulate high concentration heavy metals. Due to the increasing costs to treat remaining fly ash at the landfill, a lot of research has been done to recycle IFA. This study was focusing on the properties of IFA and cement as main raw materials in new inventive blended cement. The properties of blended cement were also being investigated. Properties of IFA and cement were examined through several test which includes density, specific gravity, X-Ray Fluorescence (XRF), Loss of Ignition (LOI) and through Toxicity Characteristic Leaching Procedure (TCLP) test. The density test and LOI test were also being done for the blended cement. From the tests for IFA and cement, it can be found that density the density of fly ash and cement that has been used for this study were found to be 0.76 g/cm3 and 3.67 g/cm3 respectively. Then, the specific gravity of fly ash and cement were 1.69 and 2.98, accordingly. XRF results shows that both materials have highest content of aluminium, silica and iron, as expected. LOI of fly ash and cement were found to be 17.33 % and 12.33 %, respectively. In terms of the leaching rates of heavy metals (Mn, Ni, Cd, Cr, Cu), only Cd leached at rate 2.39 mg/L, which is above the USEPA's regulatory level, 1.0 mg/L. 5 %, 10 % and 15 % of IFA was mixed with cement to produced blended cement. As the density of blended cement, it was found to be 1.12 g/cm3, 1.08 g/cm3 and 1.09 g/cm3 for each of 5 %, 10 % and 15 % of fly ash in blended cement.
      5  23
  • Publication
    A proposed aerobic granules size development scheme for aerobic granulation process
    ( 2015-04)
    Farrah Aini Dahalan
    ;
    Norhayati Abdullah
    ;
    Ali Yuzir
    ;
    Gustaf Olsson
    ;
    Myzairah Salmiati
    ;
    Mohd Fadhil Mohd Hamdzah
    ;
    Siti Aqlima Din
    ;
    Khalilah Abdul Ahmad
    ;
    Aznah Nor Khalil
    ;
    Zainura Zainon Anuar
    ;
    Zaini Noor
    Aerobic granulation is increasingly used in wastewater treatment due to its unique physical properties and microbial functionalities. Granule size defines the physical properties of granules based on biomass accumulation. This study aims to determine the profile of size development under two physicochemical conditions. Two identical bioreactors namely Rnp and Rp were operated under non-phototrophic and phototrophic conditions, respectively. An illustrative scheme was developed to comprehend the mechanism of size development that delineates the granular size throughout the granulation. Observations on granules’ size variation have shown that activated sludge revolutionised into the form of aerobic granules through the increase of biomass concentration in bioreactors which also determined the changes of granule size. Both reactors demonstrated that size transformed in a similar trend when tested with and without illumination. Thus, different types of aerobic granules may increase in size in the same way as recommended in the aerobic granule size development scheme.
  • Publication
    A State-of-the-Art review on innovative geopolymer composites designed for water and wastewater treatment
    ( 2021)
    Ismail Luhar
    ;
    Salmabanu Luhar
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Rafiza Abd Razak
    ;
    Petrica Vizureanu
    ;
    Andrei Victor Sandu
    ;
    Petre-Daniel Matasaru
    There is nothing more fundamental than clean potable water for living beings next to air. On the other hand, wastewater management is cropping up as a challenging task day-by-day due to lots of new additions of novel pollutants as well as the development of infrastructures and regulations that could not maintain its pace with the burgeoning escalation of populace and urbanizations. Therefore, momentous approaches must be sought-after to reclaim fresh water from wastewaters in order to address this great societal challenge. One of the routes is to clean wastewater through treatment processes using diverse adsorbents. However, most of them are unsustainable and quite costly e.g. activated carbon adsorbents, etc. Quite recently, innovative, sustainable, durable, affordable, user and eco-benevolent Geopolymer composites have been brought into play to serve the purpose as a pretty novel subject matter since they can be manufactured by a simple process of Geopolymerization at low temperature, lower energy with mitigated carbon footprints and marvellously, exhibit outstanding properties of physical and chemical stability, ion-exchange, dielectric characteristics, etc., with a porous structure and of course lucrative too because of the incorporation of wastes with them, which is in harmony with the goal to transit from linear to circular economy, i.e., “one’s waste is the treasure for another”. For these reasons, nowadays, this ground-breaking inorganic class of amorphous alumina-silicate materials are drawing the attention of the world researchers for designing them as adsorbents for water and wastewater treatment where the chemical nature and structure of the materials have a great impact on their adsorption competence. The aim of the current most recent state-of-the-art and scientometric review is to comprehend and assess thoroughly the advancements in geo-synthesis, properties and applications of geopolymer composites designed for the elimination of hazardous contaminants viz., heavy metal ions, dyes, etc. The adsorption mechanisms and effects of various environmental conditions on adsorption efficiency are also taken into account for review of the importance of Geopolymers as most recent adsorbents to get rid of the death-defying and toxic pollutants from wastewater with a view to obtaining reclaimed potable and sparkling water for reuse offering to trim down the massive crisis of scarcity of water promoting sustainable water and wastewater treatment for greener environments. The appraisal is made on the performance estimation of Geopolymers for water and wastewater treatment along with the three-dimensional printed components are characterized for mechanical, physical and chemical attributes, permeability and Ammonium (NH4+) ion removal competence of Geopolymer composites as alternative adsorbents for sequestration of an assortment of contaminants during wastewater treatment.
  • Publication
    Adsorption and toxicity of heavy metals on activated sludge
    ( 2010)
    Ong Soon An
    ;
    Eiichi Toorisaka
    ;
    Makoto Hirata
    ;
    Tadashi Hano
    The adsorption of Cu, Cd, Ni, Zn, and Cr from synthetic solutions on powdered activated carbon (PAC), activated sludge, and dried sludge were investigated under laboratory conditions to assess its ability to remove heavy metals. The adsorption efficiency increased rapidly within the first 30 min and then slowed down as it approached a steady state after 5 h of contact time. The results showed that activated sludge and PAC had a higher adsorption capacity than dried sludge. However, PAC showed a better adsorption capacity for Cu, Zn, and Ni than activated sludge. The maximum adsorption capacity, as quantified by the Langmuir parameter Q for activated sludge was 44, 30, 24, 23, and 18 mg/g for Cu, Ni, Cd, Cr, and Zn, respectively. In the case of dried sludge, the respective values of Q were 20, 13, 11, 3, and 10 mg/g. The acute toxicity of these five heavy metals to the activated sludge microorganisms was determined on the basis of the reduction in the specific oxygen uptake rate (SOUR). The results obtained from the SOUR measurements indicated a decreasing toxicity scale, Cu > Cd > Ni ' Cr > Zn on activated sludge microorganisms.
      1  12
  • Publication
    Adsorption of diclofenac sodium using low-cost activated carbon in a fixed-bed column
    ( 2022-12-15)
    Fadirah Fadzail
    ;
    Masitah Hasan
    ;
    Naimah Ibrahim
    ;
    Zulfakar Mokhtar
    ;
    Asih A.Y.P.
    ;
    Syafiuddin A.
    In recent years, the presence of pharmaceutical contaminants, such as diclofenac sodium (DCF) in water bodies and their potential influence on aquatic organisms gained much attention. As a result of high demand and usage by consumers, in addition to incomplete removal during wastewater treatment, pharmaceutical contaminants will end up on water surfaces. To mitigate this problem, the elimination of DCF by employing activated carbon derived from Dillenia Indica peels was evaluated. The adsorption of DCF was performed in a continuous process. The findings showed that the adsorption of DCF was favorable at a lower flow rate, greater bed height, and initial DCF concentration, with the highest removal percentage of 44.93%. To assess the characteristics of the breakthrough curve of DCF, the adsorption data were used to match three distinct adsorption models, namely, Boharts and Adam, Yoon-Nelson, and Thomas. The breakthrough results were well-fitted with these models, as the values of R2 for all models and parameters were higher than 0.88. Thus, it was concluded that the activated carbon from Dillenia Indica can effectively remove DCF from an aqueous solution.
      4  27
  • Publication
    Anaerobic co-digestion of different types of cow dung with food waste
    (Universitatea Gheorghe Asachi din Iasi, 2023)
    Irnis Azura Zakaria
    ;
    Nur Adlina Mohd Hilmi
    ;
    Muhd Fakhrul Samah
    ;
    Zaki Abdul Aziz Mh Daud
    ;
    Madalina Boboc
    The value of manure as a source of clean energy can be increased through the conversion of animal waste into energy, which can also reduce the negative effects that animal waste disposal has on the environment. Anaerobic digestion (AD) is a potential bioprocess for the utilisation of waste biomass and the conservation of energy. It is also an alternative method of energy recovery and waste treatment that produces biogas, which can be used to generate either electricity or heat and is a byproduct of the digestion process. In this study, different types of cow dung in terms of nutritional processes (grass: bran); 100 % grass, 95 % grass: 5 % bran, and 80 % grass: 20 % bran were taken for anaerobic co-digestion with food waste. The purpose of this study is to investigate the production of biogas as well as the properties of anaerobic co-digestion using different types of cow dung under mesophilic temperature (37°C). Biogas production was measured by the water displacement method. The pH value, Organic Matter (OM) content, C/N ratio, and Volatile Acid (VA) were recorded throughout the experiment. Samples of 100 % grass accumulated the highest biogas production (1250 ml) followed by samples of 80 % grass: 20 % bran (1080 ml) and samples of 95 % grass: 5% bran (780 ml) between the 20th and 23rd days. This shows the sample of 100 % grass-feeding has a better performance on biogas production among the samples.
      11  1
  • Publication
    Analysis of short time period of operation of horizontal ground heat exchangers
    ( 2015)
    Salsuwanda Selamat
    ;
    Akio Miyara
    ;
    Keishi Kariya
    Ground source heat pump (GSHP) systems have been proven to have higher efficiency compared to conventional air source heat pump systems for space heating and cooling applications. While vertical ground heat exchangers (GHE) are favorable in GSHP installation, this type of configuration requires higher capital costs as opposed to horizontal configuration. Numerical simulation has been used to accurately predict the thermal performance of GHE. In this paper, numerical analysis of thermal performance for slinky horizontal GHE loops in different orientations and operation modes is discussed. It was found that the loop orientation is not so important due to the little effect it has on thermal performance. While the mean heat exchange rate of copper loop increases 48% compared to HDPE loop, the analysis supports the common claim that heat exchange rate is predominantly limited by the thermal conductivity of the ground. With the same amount of circulation work, the mean heat exchange rate increases by 83%–162% when operated in parallel loops operations. The performance in these operations can be further optimized to 10%–14% increase when spacing between adjacent loops was provided. The spacing helps to minimize interference of heat flow that would penalize the overall thermal performance.
      2  17
  • Publication
    Assessment of the suitability of ceramic waste in geopolymer composites: an appraisal
    ( 2021)
    Ismail Luhar
    ;
    Salmabanu Luhar
    ;
    Mohd. Mustafa Al Bakri Abdullah
    ;
    Marcin Nabiałek
    ;
    Andrei Victor Sandu
    ;
    Janusz Szmidla
    ;
    Anna Jurczyńska
    ;
    Rafiza Abdul Razak
    ;
    Ikmal Hakem A Aziz
    ;
    Noorina Hidayu Jamil
    ;
    Laila Mardiah Deraman
    Currently, novel inorganic alumino-silicate materials, known as geopolymer composites, have emerged swiftly as an ecobenevolent alternative to contemporary ordinary Portland cement (OPC) building materials since they display superior physical and chemical attributes with a diverse range of possible potential applications. The said innovative geopolymer technology necessitates less energy and low carbon footprints as compared to OPC-based materials because of the incorporation of wastes and/or industrial byproducts as binders replacing OPC. The key constituents of ceramic are silica and alumina and, hence, have the potential to be employed as an aggregate to manufacture ceramic geopolymer concrete. The present manuscript presents a review of the performance of geopolymer composites incorporated with ceramic waste, concerning workability, strength, durability, and elevated resistance evaluation.
  • Publication
    Bridging the gap between health and safety performance and owner’s satisfaction in construction projects adopting pro-environmental construction practices: role of economic performance
    (Springer, 2023)
    Hilary Omatule Onubi
    ;
    Manuel Carpio
    ;
    Fatin Umaira Muhamad Azian
    ;
    Pirmah Binwai
    The satisfaction of clients/owners, though very important as a determinant of construction project performance, has often been given very little attention in pro-environmental-related studies. To this end, this study’s aim is to determine how owner’s satisfaction (OS) can be realized via health and safety performance (HSP) and economic performance (EP) on construction projects that adopt pro-environmental construction practices (PCP) in Nigeria and to determine how the impact of HSP on OS can vary contingent on the level of EP. This study’s aim was realized through data obtained from a survey of 249 construction projects and analyzed by adopting the partial least squares structural equation modeling (PLS-SEM) technique. The results of this study signify that HSP has a significant positive effect on OS; the nexus between HSP and OS is partially mediated by EP, while EP moderates the HSP–OS link with high EP producing the stronger effect. The practical contributions of this research emanate from the fact that its findings show that the existing gap between the level of HSP and OS is partly due to EP. Also, projects with high EP have a greater influence on the HSP–OS relationship. Therefore, to bridge the gap between HSP and OS in construction projects that adopt PCP, due attention should be given to EP.
      7  11
  • Publication
    Characterisation and evaluation of trimesic acid derivatives as disulphide cross-linked polymers for potential colon targeted drug delivery
    ( 2017)
    Siti Nur Aishah Mat Yusuf
    ;
    Ng, Yoke Mooi
    ;
    Ayub, Asila Dinie
    ;
    Ngalim, Siti Hawa
    ;
    Vuanghao Lim
    Discovery and use of biocompatible polymers offers great promise in the pharmaceutical field, particularly in drug delivery systems. Disulphide bonds, which commonly occur in peptides and proteins and have been used as drug-glutathione conjugates, are reductively cleaved in the colon. The intrinsic stability of a disulphide relative to thiol groups is determined by the redox potential of the environment. The objective of this study was to synthesise a trimesic acid-based disulphide cross-linked polymer that could potentially be used for targeted delivery to the colon. The monomer was synthesised by an amide coupling reaction between trimesic acid and (triphenylmethyl) thioethylamine using a two-step synthesis method. The s-trityl group was removed using a cocktail of trifluoroacetic acid and triethylsilane to expose the thiols in preparation for further polymerisation. The resulting polymers (P10, P15, P21, P25, and P51, generated using different molar ratios) were reduced after 1.5 h of reduction time. Scanning electron microscopy images of the polymers showed spherical, loose, or tight patterns depending on the molar ratio of polymerisation. These polymers also exhibited efficient dissolution under various gastrointestinal conditions. Of the five polymers tested, P10 and P15 appeared to be promising drug delivery vehicles for poorly soluble drugs, due to the hydrophobic nature of the polymers.
      1  22
  • Publication
    Characteristics of PM10 Level during haze events in Malaysia based on quantile regression method
    (MDPI, 2023)
    Siti Nadhirah Redzuan
    ;
    Norazian Mohamed Noor
    ;
    Nur Alis Addiena A. Rahim
    ;
    Izzati Amani Mohd Jafri
    ;
    Syaza Ezzati Baidrulhisham
    ;
    Ahmad Zia Ul-Saufie
    ;
    Andrei Victor Sandu
    ;
    Petrica Vizureanu
    ;
    Mohd Remy Rozainy Mohd Arif Zainol
    ;
    György Deák
    Malaysia has been facing transboundary haze events repeatedly, in which the air contains extremely high particulate matter, particularly PM10, which affects human health and the environment. Therefore, it is crucial to understand the characteristics of PM10 concentration and develop a reliable PM10 forecasting model for early information and warning alerts to the responsible parties in order for them to mitigate and plan precautionary measures during such events. This study aims to analyze PM10 variation and investigate the performance of quantile regression in predicting the next-day, the next two days, and the next three days of PM10 levels during a high particulate event. Hourly secondary data of trace gases and the weather parameters at Pasir Gudang, Melaka, and Petaling Jaya during historical haze events in 1997, 2005, 2013, and 2015. The Pearson correlation was calculated to find the correlation between PM10 level and other parameters. Moderate correlated parameters (r > 0.3) with PM10 concentration were used to develop a Pearson–QR model with percentiles of 0.25, 0.50, and 0.75 and were compared using quantile regression (QR) and multiple linear regression (MLR). Several performance indicators, namely mean absolute error (MAE), root mean squared error (RMSE), coefficient of determination (R2), and index of agreement (IA), were calculated to evaluate and compare the performances of the predictive model. The highest daily average of PM10 concentration was monitored in Melaka within the range of 69.7 and 83.3 µg/m3. CO and temperature were the most significant parameters associated with PM10 level during haze conditions. Quantile regression at p = 0.75 shows high efficiency in predicting PM10 level during haze events, especially for the short-term prediction in Melaka and Petaling Jaya, with an R2 value of >0.85. Thus, the QR model has high potential to be developed as an effective method for forecasting air pollutant levels, especially during unusual atmospheric conditions when the overall mean of the air pollutant level is not suitable for use as a model.
      1  3
  • Publication
    Effect of operating temperature in the anaerobic degradation of palm oil mill effluent: Process performance, microbial community, and biokinetic evaluation
    ( 2022-09-01)
    Audrey Chai Yee Chieh
    ;
    Wong Yee Shian
    ;
    Ong Soon An
    ;
    Nabilah Aminah Lutpi
    ;
    Sam Sung Ting
    ;
    Kee Wei Chin
    This research paper presents the thermophilic anaerobic digestion (TAD) of palm oil mill effluent (POME), which is an extension of a previously conducted mesophilic anaerobic digestion (MAD) study. An anaerobic suspended growth closed bioreactor was operated at various hydraulic retention times (HRT) between 24 and 8 days. The effect of operating temperature on the performance, microbial identification, and biokinetic coefficients was evaluated. Performance was quantified by the production of biogas and the chemical oxygen demand (COD) reduction efficiency. Biogas production in TAD (64.56 L/day) was higher than MAD (46.76 L/day). A higher COD reduction efficiency was also achieved in TAD (90.90%) compared to MAD (89.66%). Other than that, more species of methanogenic bacteria were also identified in TAD through 16S rDNA. Furthermore, the modified Monod model implemented in the biokinetic evaluation revealed that higher values of maximum substrate utilization rate (rx,max) and maximum specific biomass growth rate (μmax) contributed to the better performance in TAD. The high rx,max value explains the higher COD reduction efficiency obtained in TAD. The critical retention time (θC) in TAD is also higher than MAD, making it less prone to the washout of active microbes when operating near low retention times. Additionally, TAD also achieved higher methane yield (YCH4) as opposed to MAD. The extension study concluded that the TAD of POME demonstrated improved performance in terms of biogas production and COD reduction when evaluated against the previously conducted MAD.
      3
  • Publication
    Effect of temperature on flexible printed circuit board layout during reflow soldering process
    (AIP Publishing Ltd., 2023)
    Muhammad Hafifi Hafiz Ishak
    ;
    Mohd Sharizal Abdul Aziz
    ;
    Mohd Zulkifly Abdullah
    ;
    Muhammad Iqbal Ahmad
    ;
    Khor Chu Yee
    ;
    Siahaan Erwin
    High demands on flexibility, lighter weight, thinner size and low-cost electronic product had increased the application of Flexible Printed Circuit Board (FPCB) over Rigid Printed Circuit Board (RPCB). However, the thermal factor affects FPCB significantly during the reflow soldering process. The temperature of the reflow soldering process causes the FPCB to encounter significant deflection and thermal stress compared to the RPCB. Therefore, the present experiment investigates the effect of temperature on FPCB layout during the reflow soldering process. The deformation of RPCB and FPCB was measured using a KEYENCE LK-G152 laser sensor placed at the entrance and outlet of the reflow oven. Two temperature profiles were used as a variable for the experiment: soaking temperature profile and ramp temperature profile. The investigation shows that component placements pattern influences the deformation of FPCB. The FPCB component placements reduce the deformation due to low wetting angle and component weight. FPCB solder joint has a good wetting angle (<90°), indicating good solder paste deposited on the FPCB. However, several solder joints on FPCB are irregular in shape due to high deformation. Therefore, it is essential to study the effect of temperature on FPCB during the reflow soldering process for industries guideline for mass production of FPCB products.
      5  7
  • Publication
    Effects of magnesium ions in microbial cells adhesion of attached growth system for the enhancement of biogas production
    (Penerbit UTM Press, 2020)
    Nabilah Aminah Lutpi
    ;
    Wong Yee Shian
    ;
    Tengku Nuraiti Tengku Izhar
    ;
    Yiek Wee Kiong
    This research aims to improve the biogas production by employing cell immobilisation technique under thermophilic conditions. The thermophilic fermentative biogas production was carried out by immobilising the anaerobic sludge obtained from palm oil mill treatment plant on granular activated carbon (GAC) in repeated batch mode. Different concentration of magnesium ions (Mg2+) (0.25, 0.5, 0.75, 1.0 and 1.5 g/l) on biogas production was investigated at 60°C with an initial sucrose concentration of 5 g/l as feedstock. The effect of Mg2+ supplementation at the initial stage of immobilisation process is important to increase the formation of biofilm in the attached growth system. This study had found that Mg2+ could enhance the biogas production capacity with optimum Mg2+ concentration of 0.75 g/l.
  • Publication
    Enhancing ecosystem biodiversity through air pollution concentrations prediction using support vector regression approaches
    (Universitatea Gheorghe Asachi din Iasi, 2023)
    Syaidatul Umairah Solehah
    ;
    Aida Wati Zainan Abidin
    ;
    Saiful Nizam Warris
    ;
    Wan Nur Shaziayani
    ;
    Balkish Mohd Osman
    ;
    Nurain Ibrahim
    ;
    Norazian Mohamed Noor
    ;
    Ahmad Zia Ul-Saufie
    Air is the most crucial element for the survival of life on Earth. The air we breathe has a profound effect on our ecosystem biodiversity. Consequently, it is always prudent to monitor the air quality in our environment. There are few ways can be done in predicting the air pollution index (API) like data mining. Therefore, this study aimed to evaluate three types of support vector regression (linear, SVR, libSVR) in predicting the air pollutant concentration and identify the best model. This study also would like to calculate the API by using the proposed model. The secondary daily data is used in this study from year 2002 to 2020 from the Department of Environment (DoE) Malaysia which located at Petaling Jaya monitoring station. There are six major pollutants that have been focusing in this work like PM10, PM2.5, SO2, NO2, CO, and O3. The root means square error (RMSE), mean absolute error (MAE) and relative error (RE) were used to evaluate the performance of the regression models. Experimental results showed that the best model is linear SVR with average of RMSE = 5.548, MAE = 3.490, and RE = 27.98% because had the lowest total rank value of RMSE, MAE, and RE for five air pollutants (PM10, PM2.5, SO2, CO, O3) in this study. Unlikely for NO2, the best model is support vector regression (SVR) with RMSE = 0.007, MAE = 0.006, and RE = 20.75% in predicting the air pollutant concentration. This work also illustrates that combining data mining with air pollutants prediction is an efficient and convenient way to solve some related environment problems. The best model has the potential to be applied as an early warning system to inform local authorities about the air quality and can reliably predict the daily air pollution events over three consecutive days. Besides, good air quality plays a significant role in supporting biodiversity and maintaning healthy ecosystems. © 2023 Universitatea "Alexandru Ioan Cuza" din Iasi. All rights reserved.