Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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A Circular Economy Framework based on Organic Wastes Upcycling for Biodiesel Production from Hermetia illucens
Get PDFThe present waste management practices have adverse environmental impacts at the same time costly. Approximately, 80 % of the Malaysian municipal wastes including organic wastes are usual disposed into landfills. Hence, transformation organic wastes not only providing economic and environmental benefits but has given waste a value. This study focused on synthesis of biodiesel from H. illucens pre-pupae fed with fruit waste and food waste. The objective was to evaluate interactions between the variables including catalyst loading, reaction time versus fatty acid methyl esters (FAME) yield (wt %), temperature and methanol to sample mass ratio. The response surface methodology (RSM) was used to investigate the bioconversion optimization process. Optimal biodiesel yield based on fruit waste achieved was 96.15 % at 51ºC; 8.3:1 methanol: mass ratio; 253 min and 15.1 % catalyst. Furthermore, the optimal yield obtained from the second set of optimization using lipids of pre-pupae derived from food waste was achieved at 94.63 %. The optimum conditions for reaction temperature was 71°C, with methanol to mass ratio of 6.8:1, at reaction time of 254 min and catalyst loading of 7.0 v/v%. The properties of FAME produced were in accordance with EN 14214 and ASTM 6751 biodiesel standards
PEDOT:PSS Film Preparation and Characterization Using Convective Deposition System Controlled by Arduino Microcontroller for Organic Photovoltaic Application
Get PDFPEDOT:PSS films are prepared using convective deposition system. The convective deposition system is designed and controlled by a low-cost Arduino microcontroller. The microcontroller shows suitable potential for the system operation with good performance. Then, the system was applied to prepare PEDOT:PSS films and the prepared films are characterized. The prepared films reveal the increase in roughness and thickness for the high-velocity operation which could be occurred due to turbulent flows of PEDOT:PSS molecules. The result causes a decrease in transmittance, resistance, and water contact angle. For organic photovoltaic application, the enhanced power conversion efficiency is observed in corresponding to the increased short-circuit current density due to carrier transport efficiency improvement in organic photovoltaic devices provided by rough surfaces and thick films. The success of organic photovoltaic fabrication confirms the accepting ability of the convective deposition system controlled by Arduino microcontroller for non-vacuum thin film deposition. Thus, it should be considered as a usefulness system for thin-film based device fabrication with a low-cost operation
Development of Aeration-Assisted Combined Nitrification and Solid Removal Unit for a Compact Recirculating Aquaculture System
Get PDFThis work focused on the development of water treatment unit, called aeration-assisted combined nitrification and solid removal (ACNS), for compact aquaculture system. Results of preliminary study indicated that aerated filtration could extend filtration time significantly and capture more solids as compared to non-aerated filtration. Operating parameters of ACNS, including screen pore size, influent flow rate, aeration rate and position of air diffuser, were determined at 130 µm, 750 L/h, 120 L/h and 1.0 cm below the base of screen, respectively. ACNS was subsequently evaluated for its performance in nitrogen and solid removal during the 60-days closed-water tilapia cultivation. Performance of aquaculture system with ACNS, as the only treatment unit, was comparable to the aquaculture system having both nitrifying biofilter and ACNS, as separated units. Specifically, ACNS could maintain suspended solids (28 ± 7.6 mg SS/L), ammonia (< 0.5 mg N/L) and nitrite (< 0.5 mg N/L) concentration below the recommended limits for extended period. ACNS also produced relatively high and constant effluent flux close to initial value despite increasing the filtration time in aerated compartment up to 7 days. This led to continuous filtration, without stopping the system to remove solids on screen, for 50 days
Assessing BIM Adoption towards Reliability in QS Cost Estimates
Get PDFBIM technology has been evolving around the world in recent years. As in Malaysia, the country has initiated BIM in its current Construction Industry Transformation Programme (CITP) 2016-2020. One of the CITP agenda is to encourage BIM usage to assist the construction players in improving their current practices towards better productivity, hence better sustainability within the construction industry. In quantity surveying field, the technology potentially helps the Quantity Surveyors to accelerate the process of taking-off building quantities, subsequently establishing more reliable and sustainable cost estimates. Although BIM is claimed to upgrade the conventional methods of the measurement tasks, there are still some limitations of BIM innovation, with previous studies lacking explanation in identifying those issues. Therefore, this study aims to investigate the effectiveness of using BIM to aid Malaysian Quantity Surveyors primarily in cost estimating towards composing sustainability elements in the construction industry. To achieve this, a series of focus group discussions were conducted amongst BIM and non-BIM users. Through content analysis, it resulted that the capabilities of estimators in occupying BIM is critical to accomplish the sustainable benefits of the technology. It engages skills in both technology usage and traditional methods of measurement to achieve holistic knowledge of building construction. Thus, it enhances the performance of the estimators to likely generate reliability and sustainability in their cost estimates. This study contributes towards better understanding of cost estimating incorporating BIM and sustainability settings in quantity surveying practice
The Development Control Process for Residential and Serviced Apartments in Shah Alam, Selangor
Get PDFThe lack of understanding on the development control process for residential and serviced apartments causes developers took advantage by placing unreasonable house prices leaving negative impacts to the purchasers. This becomes a growing concern whereby the growth of apartments has increased throughout the years in Malaysia. Therefore, the objectives of this study are to compare the serviced apartment and residential apartment in Shah Alam from the aspects of design guidelines and planning standards, the development requirements including the density and plot ratio, the submission requirements, and the legal matters involved in the development of these apartments. An analysis is done based on the data obtained from relevant Acts, Manuals, Checklists and interviews with fourteen (14) representatives from Shah Alam City Council, developers and apartments management body that is involved in the process. The results of the study indicate the differences between the serviced apartment and residential apartment. The findings present a synthesis of results for town planners, architects, developers and, government agencies to have a better understanding on the development control process for apartments that further can rationalize the success of property development sector
Post Occupancy Evaluation of Space Energy Intensity on Green Building Index Energy Efficiency (EE) Criteria
Get PDFGreen interior tool sustainable benchmarking system in Malaysian is relatively new. Despite of the launch of Malaysian Green Building Councils very own Green Interior Tools (GBI-IT) and implementation, there is still deficiency in post-occupancy measure being conducted in evaluating the holistic sustainability level on the post-certified interior project. The lacking is in particular related to the Space Energy Intensity (SEI). Thus, embark the study problem whether the certified project sustainability level is in accord to pre-occupancy rating score as parallel to vision by the designers upon occupation, in particular on Energy Efficiency (EE). The study objectives is to examine the SEI, to identify similarities and discrepancies of SEI and to weigh the main EE sub-criteria which effect SEI in order to enhance continuing sustainable EE after one year occupation. The SEI equation method and implementation approach are conducted in this concept paper by measuring the total space energy consumption per year/interior space area. The study design are devised into three key phases; 1. Content analysis of GBI-IT EE core criteria; 2. Comparative data analysis between post-occupancy and simulated pre-occupancy scoring level and; 3. Evaluation of key EE sub-criteria that affect SEI in order to improve continuing sustainability after occupation. The findings and discussions based on SEI comparative analysis will improve sustainability practice towards continuing sustainable agenda and will facilitate further enhancement for future sustainable approach in interior SEI
Effects of Carbonation on Corrosion Rate of Reinforcing Steel in Different Concrete and Repair Materials
Get PDFReinforced concrete with different concrete mix proportions, i.e. binder types or w/b ratio, would provide different quality to protect the reinforcing steel from corrosion. When carbonation occurred, corrosion of steel embedded in concrete can be initiated. This paper reports effects of carbonation on electrochemical properties of steel embedded in concrete with different mix proportions as w/b ratio of 0.4 and 0.6, fly ash added up to 30% by weight of binder, and also in six repair materials. All samples was exposed to accelerated carbonation (4% CO2, 50 ± 5% relative humidity (RH), and 40 0C temperature) and laboratory environment (0.04% CO2, 75 ± 5% RH, and 28 0C). The electrical resistivity was monitored by using four-point Wenner probe. The Linear polarization resistance (LPR) was used to characterize the corrosion rate of embedded steel at different exposure time. The carbonation depth of specimens was also tested by using the phenolphthalein indicator. The void contents of repair material specimens were also determined. The results showed that the electrical resistivity of concretes and repair materials increased along with an increase of carbonation depth. However, in case of fly ash concrete, the electrical resistivity decreased at longer exposure period in accelerated carbonation due to decomposition of C-S-H by carbonation. It was also found that the corrosion rate of steel embedded in concrete and repair materials increased as an increase of carbonation depth, even the carbonation depth was less than the covering depth. Steel embedded in ordinary Portland cement (OPC) concrete or low w/b concrete shows lower corrosion rate due to higher pH of concrete. The guideline for evaluation of corrosion initiation and severity due to carbonation is also proposed
Evaluation and Improvement of the Efficiency of Logistics Companies with Data Envelopment Analysis Model
Get PDFThe performance of global trade depends on the logistics industry to move products, information, finances, technology and human resources along the supply chain. The current situation during the pandemic relies on the logistics industry particularly in the courier, parcel and express service providers to deliver daily essentials. Product customization, customer demand, technological sophistication, threat of new entrants, border closure, compliance to Covid-19 regulations and global economic crisis have taken the logistics industry by storm. For the sustainment and growth of these companies, strategic decision making shall take place. A huge determinant of these decisions is the financial efficiency of the companies. Therefore, this paper aims to determine the efficiency of the logistics companies in Malaysia by analyzing their financial performances using current ratio, debt to assets ratio, debt to equity ratio, earnings per share, return on assets and return on equity with data envelopment analysis model. The results of this study found that five companies, COMPLET, GDEX, MISC, SURIA and WPRTS are efficient. This study fills the research gap by determining the efficiency scores of these companies and suggesting potential improvements for inefficient companies to enhance and optimize their financial positions
Coating Gold Nanoparticles Synthesized from Spent Coffee Ground Extract to Enhance Their Stability
Get PDFGold nanoparticles (AuNPs) were synthesized using the extract from cold-brew spent coffee grounds. The colloids were characterized by UV-vis spectrophotometry and transmission electron microscopy. When using 1.8 mM and 4.0 mM HAuCl4, the average diameter of AuNPs was 10.51 and 13.75 nm, corresponding to the peak at 533 and 539, respectively. The colloidal stability was studied using the results from spectrophotometry. The aggregation of as-synthesized AuNPs, reflected by the red shift of the spectrum, occurred after the centrifugation at 10000 rpm for 10 minutes but this was prevented after coating with 5%w/v PEG400, 5%w/v PEG6000, 0.1%w/v alginate, and 0.5%w/v SDS solutions. Electrostatic stabilization using alginate and SDS could withstand up to three times of centrifugation, while steric stabilization using PEG400 and PEG6000 could withstand the disturbance of Ca2+ more effectively. The smaller AuNPs were more affected by Ca2+ than the larger ones. In highly acidic solutions, all coated AuNPs showed the red shift and SDS-coated AuNPs were the most effective against acid disturbance, and in highly basic solutions, all coated AuNPs showed the blue shift. Besides, the coated AuNPs were still stable at 52ºC. This study could be applied in situations where mechanical, chemical, thermal and acid disturbances are concerned
New Product Development Processes for IOT-Enabled Home Use Medical Devices: A Systematic Review
Get PDFBackground: In the new forefront of healthcare at patients’ homes, medical devices developed to use at home setting by lay users are essential. The adoption of home-use medical devices will benefit both patients and public healthcare services in terms of quality of life, enhanced outcomes, and reduced cost of care. Home use medical devices associated with Internet-Of-Things (IOT) technology assists patients in performing self-care as well as providing health information remotely to health care professionals. However, adopting technology requires understanding the nature of the medical device and medical device development (MDD). Existing studies concerning the new product development (NPD) processes or design processes were systematically reviewed to explore knowledge and expertise to provide a framework for IOT engineers or designers to adopt IOT technology to home use medical devices.
Objective: This study aimed to review the published literature to explore the current studies in the field of the NPD process, design process, design methodology, and outcome of the device affecting user acceptance.
Methods: A systematic review following PRISMA guidelines of the English language literature from four electronic databases and academic search engines published from 2007 to 2018 was conducted. The papers were screened and assessed following predefined inclusive and exclusive criteria. The results were analyzed according to the research questions.
Results: The findings revealed state-of-the-art in the NPD process and design process (n=4), the design methodology (n=23), and the resultant outcomes of empirical or clinical research in the validation stage (n=14) of medical device development (MDD). The findings also delineated existing studies in NPD, design process, and design methodologies aimed to ensure that medical devices would be effective and safe. Human factor engineering (HFE), cognitive method, ethnographic, and other methodologies were proposed to understand users, uses and context of use. Barriers, constraints, and multidisciplinary communication were addressed. Tools, processes, and methodologies were proposed to overcome the barriers.
Conclusion: As home-use medical device development (MDD) and the adoption of IOT technology is now at a crossroads. This study addresses the necessity for future academic studies related to IOT adoption to MDD, including unique risks, multidisciplinary problems, emerging from IOT technology. Finally, future studies aimed at fabricating the NPD process or design process for IOT home-use medical devices to gain user acceptance were outlined