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Prof. Aristotle Ubando
Mechanical Engineering Department, De La Salle University, 2401 Taft Avenue, 0922, Manila, Philippines

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0 Bioenergy
0 Process Optimization
0 Biorefinery
0 Systems Integration
0 Microalgal processes

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Original paper
Published: 03 June 2021 in Clean Technologies and Environmental Policy
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Urban systems have a central role in the transition toward circular economy. Systematic analysis of drivers is needed because of the complex interplay of social, economic, and political factors. Such analysis requires a good understanding of direct and indirect influences on urban circularity. Because of the presence of indirect influences, visualizing the causal networks is necessary for systematic analysis. Existing methods for formulating causal network maps (CNMs) rely on subjective approaches which inhibit robust assessment. The generation of robust CNMs can provide more accurate representation of direct and indirect influences. Therefore, this study generates a robust CNM for drivers of urban circular economy through a hybrid decision-making and trial laboratory-fuzzy cognitive map (DEMATEL-FCM) framework. DEMATEL is used for building the initial structure of the network map. The network is then trained using FCM with data obtained from the Sustainable Cities Index. A 70:30 training–testing ratio is used to partition the training and testing datasets. The trained CNM has 92.75% accuracy during training and 96.77% accuracy during testing. The trained CNM provides an empirical depiction of driver interrelationships in urban circular economies. It indicates the importance of ‘affordability’ and ‘economic development’ in the network structure. The network yields significant insights for the development of city-level plans and policies to stimulate a transition to a more circular economy. Data-driven visualization of interactions among drivers give stakeholders insights on the most effective measures to implement.

ACS Style

Ivan Henderson V. Gue; Raymond R. Tan; Aristotle T. Ubando. Causal network maps of urban circular economies. Clean Technologies and Environmental Policy 2021, 1 -12.

AMA Style

Ivan Henderson V. Gue, Raymond R. Tan, Aristotle T. Ubando. Causal network maps of urban circular economies. Clean Technologies and Environmental Policy. 2021; ():1-12.

Chicago/Turabian Style

Ivan Henderson V. Gue; Raymond R. Tan; Aristotle T. Ubando. 2021. "Causal network maps of urban circular economies." Clean Technologies and Environmental Policy , no. : 1-12.

Journal article
Published: 28 April 2021 in Environmental Pollution
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A green approach using hydrogen peroxide (H2O2) to intensify the fuel properties of spent coffee grounds (SCGs) through torrefaction is developed in this study to minimize environmental pollution. Meanwhile, a neural network (NN) is used to minimize bulk density at different combinations of operating conditions to show the accurate and reliable model of NN (R2 = 0.9994). The biochar produced from SCGs torrefied at temperatures of 200–300 °C, duration of 30–60 min, and H2O2 concentrations of 0–100 wt% is examined. The results reveal that the higher heating value (HHV) of biochar increases with rising temperature, duration, or H2O2 concentration, whereas the bulk density has an opposite trend. The HHV, ignition temperature, and bulk density of biochar from torrefaction at 230 °C for 30 min with a 100 wt% H2O2 solution (230-100%-TSCG) are 27.00 MJ∙kg−1, 292 °C, and 120 kg∙m−3, respectively. This HHV accounts for a 29% improvement compared to that of untorrefied SCG. The contact angle (126°), water activity (0.51 aw), and moisture content (7.69%) of the optimized biochar indicate that it has higher resistance against biodegradation, and thereby can be stored longer. Overall, H2O2 is a green treatment additive for SCGs solid fuel. This study has successfully produced biochar with greater HHV and low bulk density at low temperatures. The green additive development can effectively reduce environmental pollutants and upgrade wastes into resources, and achieve “3E”, namely, environmental (non-polluting green additives), energy (biofuel), and circular economy (waste upgrade). In addition, the produced biochar has great potential in the fields of bioadsorbents and soil amendments.

ACS Style

Kuan-Ting Lee; Jyun-Ting Du; Wei-Hsin Chen; Aristotle T. Ubando; Keat Teong Lee. Green additive to upgrade biochar from spent coffee grounds by torrefaction for pollution mitigation. Environmental Pollution 2021, 285, 117244 .

AMA Style

Kuan-Ting Lee, Jyun-Ting Du, Wei-Hsin Chen, Aristotle T. Ubando, Keat Teong Lee. Green additive to upgrade biochar from spent coffee grounds by torrefaction for pollution mitigation. Environmental Pollution. 2021; 285 ():117244.

Chicago/Turabian Style

Kuan-Ting Lee; Jyun-Ting Du; Wei-Hsin Chen; Aristotle T. Ubando; Keat Teong Lee. 2021. "Green additive to upgrade biochar from spent coffee grounds by torrefaction for pollution mitigation." Environmental Pollution 285, no. : 117244.

Earlycite article
Published: 11 March 2021 in Built Environment Project and Asset Management
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Purpose The self-cleaning properties of nanostructured titanium dioxide facade coatings are useful in Singapore's tropical climate. However, its potential maintenance issues need to be determined right at the design stage. The purpose of this paper is to highlight the development of the design for maintainability tool which is a multicriteria design decision score sheet that evaluates the maintainability potential of nano-facade coating applications on high-rise façades with concrete and stonemasonry finishes and curtain walls. Design/methodology/approach Quantitative methods (expert and practitioner surveys) are conducted in this research study. Analytic hierarchy process (AHP) and sensitivity analysis were used to develop a robust Design for Maintainability tool. Findings Safety measures indicator received the highest weighted score by experts, while the maximizing performance, minimizing risk, minimizing negative environmental impact and minimizing consumption of matter and energy were the top ranking main criteria by both experts and practitioners. The top ranked design for maintainability sub-criteria identified by practitioners and experts were risk management, maintenance considerations, climatic conditions, safety measures, lifecycle cost and maintenance access, sun's path, rainfall intensity, biological growth measures and building age profile. Originality/value Most researches on the maintainability of nano-façade coatings uses experimentation to test the durability of nano-façade coatings, while this study focuses on design based empirical data such as establishing and ranking the list of design for maintainability criteria or indicators to minimize future defects and maintenance issues. The design for maintainability tool contributes to the maintainability of nano-façade coatings leading to maximizing its performance while minimizing cost, risks, resource consumption and negative environmental impact.

ACS Style

Sheila Conejos; Aristotle Ubando; Michael Yit Lin Chew. Design for maintainability tool for nano-façade coating applications on high-rise facades in the tropics. Built Environment Project and Asset Management 2021, ahead-of-p, 1 .

AMA Style

Sheila Conejos, Aristotle Ubando, Michael Yit Lin Chew. Design for maintainability tool for nano-façade coating applications on high-rise facades in the tropics. Built Environment Project and Asset Management. 2021; ahead-of-p (ahead-of-p):1.

Chicago/Turabian Style

Sheila Conejos; Aristotle Ubando; Michael Yit Lin Chew. 2021. "Design for maintainability tool for nano-façade coating applications on high-rise facades in the tropics." Built Environment Project and Asset Management ahead-of-p, no. ahead-of-p: 1.

Journal article
Published: 04 March 2021 in Energies
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Biofuel production from microalgae biomass has been considered a viable alternative to harmful fossil fuels; however, challenges are faced regarding its economic sustainability. Process integration to yield various high-value bioproducts is implemented to raise profitability and sustainability. By incorporating a circular economy outlook, recirculation of resource flows is maximized to yield economic and environmental benefits through waste minimization. However, previous modeling studies have not looked into the opportunity of integrating productivity reduction related to the continuous recirculation and reuse of resources until it reaches its end of life. In this work, a novel multi-objective optimization model is developed centered on an algal biorefinery that simultaneously optimizes cost and environmental impact, adopts the principle of resource recovery and recirculation, and incorporates the life cycle assessment methodology to properly account for the environmental impacts of the system. An algal biorefinery involving end-products such as biodiesel, glycerol, biochar, and fertilizer was used for a case study to validate the optimization model. The generated optimal results are assessed and further analyzed through scenario analysis. It was seen that demand fluctuations and process unit efficiencies have significant effect on the optimal results.

ACS Style

Celine Solis; Jayne San Juan; Andres Mayol; Charlle Sy; Aristotle Ubando; Alvin Culaba. A Multi-Objective Life Cycle Optimization Model of an Integrated Algal Biorefinery toward a Sustainable Circular Bioeconomy Considering Resource Recirculation. Energies 2021, 14, 1416 .

AMA Style

Celine Solis, Jayne San Juan, Andres Mayol, Charlle Sy, Aristotle Ubando, Alvin Culaba. A Multi-Objective Life Cycle Optimization Model of an Integrated Algal Biorefinery toward a Sustainable Circular Bioeconomy Considering Resource Recirculation. Energies. 2021; 14 (5):1416.

Chicago/Turabian Style

Celine Solis; Jayne San Juan; Andres Mayol; Charlle Sy; Aristotle Ubando; Alvin Culaba. 2021. "A Multi-Objective Life Cycle Optimization Model of an Integrated Algal Biorefinery toward a Sustainable Circular Bioeconomy Considering Resource Recirculation." Energies 14, no. 5: 1416.

Conference paper
Published: 01 March 2021 in IOP Conference Series: Materials Science and Engineering
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Proper design of semiconductors is the most essential step in ensuring electronic product reliability during manufacturing. The adoption of design optimization approach enhances the performance and reliability of the semiconductor package, hence, minimizes product failure. Semiconductor reliability especially in the application to automobiles is very crucial. High product failure tolerance in semiconductors in automobiles is required due to problems such as defects and malfunctions that are directly linked to casualty accidents. Such high tolerance requires keen quality control up to the semiconductor solder component level. This study aims to do a sensitivity analysis of the solder balls' material properties and its effect on the stresses experienced by the semiconductor component with respect to its reliability using drop test. A drop test analysis was simulated wherein a shorter distance of 5 mm between the package and platform was implemented to make the simulation time faster. The density and modulus of elasticity of the solder ball material were identified as the independent factors while the stresses experienced by the BGA package during the drop test is the dependent variable. The results have shown that the maximum stress for all runs was found in the same area in the package. Changing the modulus of elasticity showed greater effect on the impact stress compared to the alteration of material density.

ACS Style

J Gonzaga; A T Ubando; E Arriola; R L Moran; N R E Lim; J P Mercado; A Conversion; D Belarmino. Drop test analysis of ball grid array package using finite element method. IOP Conference Series: Materials Science and Engineering 2021, 1109, 012023 .

AMA Style

J Gonzaga, A T Ubando, E Arriola, R L Moran, N R E Lim, J P Mercado, A Conversion, D Belarmino. Drop test analysis of ball grid array package using finite element method. IOP Conference Series: Materials Science and Engineering. 2021; 1109 (1):012023.

Chicago/Turabian Style

J Gonzaga; A T Ubando; E Arriola; R L Moran; N R E Lim; J P Mercado; A Conversion; D Belarmino. 2021. "Drop test analysis of ball grid array package using finite element method." IOP Conference Series: Materials Science and Engineering 1109, no. 1: 012023.

Conference paper
Published: 01 March 2021 in IOP Conference Series: Materials Science and Engineering
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Semiconductors and electronics have been found to have an increasing use in automobile design. One key component of an automobile is the power module, which is a high voltage component that finds itself in extreme operating conditions. Due to this condition, the power module demands for highly effective terminal connections that can withstand the extreme operating condition specifically on the terminals that will connect the power module to the automobile system. Press fit technology has been a solution for cheap and reliable methods of creating interconnections since the 1980s; however, necessary innovations exist for more environmental design, and increase demand in quality and quantity. Press fits are simple, force-fitting connectors that allow permanent bonds without solder or adhesive bonding and a shortened process time. This research presents a unique methodology on the evaluation of the effects of the geometry to the insertion force and retention force using finite element analysis. The result showed that the geometry of the pin in a press fit pin configuration has a significant effect on the insertion force, retention force, as well as in the equivalent stress.

ACS Style

A T Ubando; J Gonzaga; E Arriola; R L Moran; N R E Lim; J P Mercado; A Conversion; D Belarmino. Analysis of the effects of geometry on the press fit application in automotive power modules. IOP Conference Series: Materials Science and Engineering 2021, 1109, 012019 .

AMA Style

A T Ubando, J Gonzaga, E Arriola, R L Moran, N R E Lim, J P Mercado, A Conversion, D Belarmino. Analysis of the effects of geometry on the press fit application in automotive power modules. IOP Conference Series: Materials Science and Engineering. 2021; 1109 (1):012019.

Chicago/Turabian Style

A T Ubando; J Gonzaga; E Arriola; R L Moran; N R E Lim; J P Mercado; A Conversion; D Belarmino. 2021. "Analysis of the effects of geometry on the press fit application in automotive power modules." IOP Conference Series: Materials Science and Engineering 1109, no. 1: 012019.

Conference paper
Published: 01 March 2021 in IOP Conference Series: Materials Science and Engineering
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The automotive industry places electronic components in vastly different conditions compared to that for residential purposes. Thus, there are certain components that have found an essential use in this industry. One such component is the press fit pin. The press fit pin is seen as an alternative to soldering because it is cheaper to implement and more reliable at times. All technologies however, come with disadvantages. One of the common issues encountered by press fit pins are the excessive stresses on both the pin and the hole during insertion which tend to cause deformation or cracks in the substrate material. Because of this, the main topics of research on press fit pins are most commonly on the insertion forces and retention forces present. These forces occur on the interfaces between the pin and the hole where it is inserted. Therefore, there have been several studies on the friction between the two components. The studies however, only explored the frictional coefficient of their present system which reduces its applicability on other designs. This work seeks to present an in-depth finite element analysis on the effects of varying frictional coefficients would have on the equivalent stress and retention forces present on the press fit pins.

ACS Style

J Gonzaga; A T Ubando; E Arriola; R L Moran; N R E Lim; J P Mercado; A Conversion; D Belarmino. Finite element analysis of frictional coefficients in press fit pins. IOP Conference Series: Materials Science and Engineering 2021, 1109, 012027 .

AMA Style

J Gonzaga, A T Ubando, E Arriola, R L Moran, N R E Lim, J P Mercado, A Conversion, D Belarmino. Finite element analysis of frictional coefficients in press fit pins. IOP Conference Series: Materials Science and Engineering. 2021; 1109 (1):012027.

Chicago/Turabian Style

J Gonzaga; A T Ubando; E Arriola; R L Moran; N R E Lim; J P Mercado; A Conversion; D Belarmino. 2021. "Finite element analysis of frictional coefficients in press fit pins." IOP Conference Series: Materials Science and Engineering 1109, no. 1: 012027.

Conference paper
Published: 01 March 2021 in IOP Conference Series: Materials Science and Engineering
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- Automotive electronics can produce an unprecedented level of passenger comfort and optimized performance of engine and components. However, the increasing intricacy of these electronic devices makes them more susceptible to damage due to thermal loads, mechanical drops, and engine vibrations. While physical handling of automotive components is comparatively rare, the weight and complexity of specific components such as the ECU, power module, and sensor modules, makes any drop functionally fatal. Simulation approach is considered to be essential in solving these problems by minimizing costs and effort. This paper attempts to solve the issue of mechanical drops using an explicit dynamics finite element analysis solver. Moreover, simplification methods are applied to further minimize solution costs.

ACS Style

A T Ubando; J Gonzaga; N R E Lim; J P Mercado; E Arriola; R L Moran; A Conversion; D Belarmino. Exploring simplification methods in reducing simulation time for drop test analysis. IOP Conference Series: Materials Science and Engineering 2021, 1109, 012026 .

AMA Style

A T Ubando, J Gonzaga, N R E Lim, J P Mercado, E Arriola, R L Moran, A Conversion, D Belarmino. Exploring simplification methods in reducing simulation time for drop test analysis. IOP Conference Series: Materials Science and Engineering. 2021; 1109 (1):012026.

Chicago/Turabian Style

A T Ubando; J Gonzaga; N R E Lim; J P Mercado; E Arriola; R L Moran; A Conversion; D Belarmino. 2021. "Exploring simplification methods in reducing simulation time for drop test analysis." IOP Conference Series: Materials Science and Engineering 1109, no. 1: 012026.

Journal article
Published: 18 January 2021 in Biomass and Bioenergy
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Microbial fuel cells (MFCs) provide an efficient way to utilize energy from biomass while it offer advantages such as pollution avoidance, high energy conversion efficiency, and flexibility for a wide range of applications. MFCs have gained much attention and are considered as current research hotspot in bioenergy. To further improve the reaction area, microbial compatibility, and to increase the power generation efficiency in the design and manufacturing of a small-scale MFC, the use of 3D printing technology and the employment of a high-efficiency mixing area are proposed in this work. Carbon cloth is employed as the electrode substrate of the MFC. Moreover, the carbon nanotubes and graphene dispersions are used to modify the carbon electrode plates. The results show that the graphene modified carbon cloth electrode MFC has a maximum power density of 199.24 mW m−2 at a current density of 1.52 A m−2. While the unmodified carbon cloth electrode MFC has a current density of 0.63 A m−2. This indicates that the graphene modified carbon cloth electrode MFC achieved a maximum power density of about 232% compared with the unmodified carbon cloth electrode MFC. The lowest internal resistance obtained was 0.66 kΩ when the electron transfer medium was accounted. This indicated a low anode impedance which is desired in MFC systems. Result revealed that the graphene modified carbon cloth electrode is the best electrode material based on the enhanced power density and lowered internal resistance. The results of the work aims to provide insight in the improvement of the MFC electrode modification technology.

ACS Style

Song-Jeng Huang; Aristotle T. Ubando; Chuan-Yun Wang; Yi-Xun Su; Alvin B. Culaba; Yu-An Lin; Chin-Tsan Wang. Modification of carbon based cathode electrode in a batch-type microbial fuel cells. Biomass and Bioenergy 2021, 145, 105972 .

AMA Style

Song-Jeng Huang, Aristotle T. Ubando, Chuan-Yun Wang, Yi-Xun Su, Alvin B. Culaba, Yu-An Lin, Chin-Tsan Wang. Modification of carbon based cathode electrode in a batch-type microbial fuel cells. Biomass and Bioenergy. 2021; 145 ():105972.

Chicago/Turabian Style

Song-Jeng Huang; Aristotle T. Ubando; Chuan-Yun Wang; Yi-Xun Su; Alvin B. Culaba; Yu-An Lin; Chin-Tsan Wang. 2021. "Modification of carbon based cathode electrode in a batch-type microbial fuel cells." Biomass and Bioenergy 145, no. : 105972.

Research article
Published: 08 December 2020 in International Journal of Energy Research
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Microbial fuel cells (MFCs) are considered as power generation devices for sustainable energy. However, the power generated is insignificant compared to other energy production devices. In this study, a mini autonomous biosensor (MAB) based on MFCs has been designed for detecting hazardous hexavalent chromium in wastewater. Hexavalent chromium has been classified as a human carcinogen causing serious birth defects due to its mutagenic and teratogenic properties. The power generated by the MAB has been investigated to study the feasibility of providing power to itself. In addition, electrochemical analyses of conductive silver paste and carbon cloth as the anode were conducted in the MAB for detecting hexavalent chromium in the anode chamber. Results show that a maximum voltage of 518.17 mV and a power density of 1.075 mW/cm2 could be achieved using carbon cloth with an external resistance of 1000 Ω, while a higher limiting current density of 0.015 mA/cm2 could be achieved with conductive silver glue as the anode electrode. Besides, the voltage output of the MAB decreased rapidly with the addition of hexavalent chromium into the wastewater. Also, the recovery time for the MAB was much shorter than found in previous studies. The MAB demonstrated potential for simultaneous production of electricity and detection of hexavalent chromium, which would open up avenues for autosensing applications in the environment as well as smart powering devices. Results indicate that the MAB with conductive silver glue as anode electrode is feasible for detecting hexavalent chromium in wastewater.

ACS Style

Chin‐Tsan Wang; Aristotle T. Ubando; Vimal Katiyar; T‐Ting Li; Yu‐An Lin; Alvin B. Culaba; Jer‐Huan Jang. Feasibility study on a mini autonomous biosensor based on microbial fuel cell for monitoring hexavalent chromium in wastewater. International Journal of Energy Research 2020, 45, 6293 -6302.

AMA Style

Chin‐Tsan Wang, Aristotle T. Ubando, Vimal Katiyar, T‐Ting Li, Yu‐An Lin, Alvin B. Culaba, Jer‐Huan Jang. Feasibility study on a mini autonomous biosensor based on microbial fuel cell for monitoring hexavalent chromium in wastewater. International Journal of Energy Research. 2020; 45 (4):6293-6302.

Chicago/Turabian Style

Chin‐Tsan Wang; Aristotle T. Ubando; Vimal Katiyar; T‐Ting Li; Yu‐An Lin; Alvin B. Culaba; Jer‐Huan Jang. 2020. "Feasibility study on a mini autonomous biosensor based on microbial fuel cell for monitoring hexavalent chromium in wastewater." International Journal of Energy Research 45, no. 4: 6293-6302.

Journal article
Published: 31 October 2020 in Environmental Technology & Innovation
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This study investigated the synergistic effect of co-torrefaction with intermediate waste epoxy resins and fir in a batch-type reactor towards biochar improvement. The synergistic effect ratio was used to judge the interaction between the two materials assisted by statistical tools. The main interaction between the feedstocks was the catalytic reaction and blocking effect. Sodium presented in the intermediate waste had a pronounced catalytic effect on the liquid products during torrefaction. It successfully enhanced the volatile matter emissions and exhibited an antagonistic effect on the solid yield. Different from the catalytic reaction that occurred during short retention time, the blocking effect was more noticeable with a longer duration, showing a synergistic effect on the solid yield. Alternatively, a significantly antagonistic effect was exerted on oxygen content, while the carbon content displayed a converse trend. This gave rise to a major antagonistic effect on the O/C ratio which was closer to coal for pure materials torrefaction. The other spotlight in this study was to reuse the tar as a heating value additive. After coating it onto the biochar, the higher heating value could be increased by up to 5.4%. Although tar is considered as an unwanted byproduct of torrefaction treatment, the presented data show its high potential to be recycled into useful calorific value enhancer. It also fulfills the scope of waste-to-energy in this study.

ACS Style

Chia-Yang Chen; Wei-Hsin Chen; Steven Lim; Hwai Chyuan Ong; Aristotle T. Ubando. Synergistic interaction and biochar improvement over co-torrefaction of intermediate waste epoxy resins and fir. Environmental Technology & Innovation 2020, 21, 101218 .

AMA Style

Chia-Yang Chen, Wei-Hsin Chen, Steven Lim, Hwai Chyuan Ong, Aristotle T. Ubando. Synergistic interaction and biochar improvement over co-torrefaction of intermediate waste epoxy resins and fir. Environmental Technology & Innovation. 2020; 21 ():101218.

Chicago/Turabian Style

Chia-Yang Chen; Wei-Hsin Chen; Steven Lim; Hwai Chyuan Ong; Aristotle T. Ubando. 2020. "Synergistic interaction and biochar improvement over co-torrefaction of intermediate waste epoxy resins and fir." Environmental Technology & Innovation 21, no. : 101218.

Journal article
Published: 28 September 2020 in Sustainability
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As the demand for biofuels increases globally, microalgae offer a viable biomass feedstock to produce biofuel. With abundant sources of biomass in rural communities, these materials could be converted to biodiesel. Efforts are being done in order to pursue commercialization. However, its main usage is for other applications such as pharmaceutical, nutraceutical, and aquaculture, which has a high return of investment. In the last 5 decades of algal research, cultivation to genetically engineered algae have been pursued in order to push algal biofuel commercialization. This will be beneficial to society, especially if coupled with a good government policy of algal biofuels and other by-products. Algal technology is a disruptive but complementary technology that will provide sustainability with regard to the world’s current issues. Commercialization of algal fuel is still a bottleneck and a challenge. Having a large production is technical feasible, but it is not economical as of now. Efforts for the cultivation and production of bio-oil are still ongoing and will continue to develop over time. The life cycle assessment methodology allows for a sustainable evaluation of the production of microalgae biomass to biodiesel.

ACS Style

Alvin Culaba; Aristotle Ubando; Phoebe Ching; Wei-Hsin Chen; Jo-Shu Chang. Biofuel from Microalgae: Sustainable Pathways. Sustainability 2020, 12, 8009 .

AMA Style

Alvin Culaba, Aristotle Ubando, Phoebe Ching, Wei-Hsin Chen, Jo-Shu Chang. Biofuel from Microalgae: Sustainable Pathways. Sustainability. 2020; 12 (19):8009.

Chicago/Turabian Style

Alvin Culaba; Aristotle Ubando; Phoebe Ching; Wei-Hsin Chen; Jo-Shu Chang. 2020. "Biofuel from Microalgae: Sustainable Pathways." Sustainability 12, no. 19: 8009.

Journal article
Published: 21 September 2020 in Sustainability
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Given increasing energy demand and global warming potential, the advancements in bioenergy production have become a key factor in combating these issues. Biorefineries have been effective in converting biomass into energy and valuable products with the added benefits of treating wastewater used as a cultivation medium. Recent developments enable relationships between sewage sludge and microalgae that could lead to higher biomass and energy yields. This study proposes a multi-objective optimization model that would assist stakeholders in designing an integrated system consisting of wastewater treatment systems, an algal-based bioenergy park, and a sludge-based bioenergy park that would decide which processes to use in treating wastewater and sludge while minimizing cost and carbon emissions. The baseline run of the model showed that the three plants were utilized in treating both sludge and water for the optimal answer. Running the model with no storage prioritizes water disposal, while having storage can help produce more energy. Sensitivity analysis was performed on storage costs and demand. Results show that decreasing the demand is directly proportional to the total costs while increasing it can help reduce expected costs through storage and utilizing process capacities. Costs of storage do not cause a huge overall difference in costs and directly follow the change.

ACS Style

Jayne Juan; Carlo Caligan; Maria Garcia; Jericho Mitra; Andres Mayol; Charlle Sy; Aristotle Ubando; Alvin Culaba. Multi-Objective Optimization of an Integrated Algal and Sludge-Based Bioenergy Park and Wastewater Treatment System. Sustainability 2020, 12, 7793 .

AMA Style

Jayne Juan, Carlo Caligan, Maria Garcia, Jericho Mitra, Andres Mayol, Charlle Sy, Aristotle Ubando, Alvin Culaba. Multi-Objective Optimization of an Integrated Algal and Sludge-Based Bioenergy Park and Wastewater Treatment System. Sustainability. 2020; 12 (18):7793.

Chicago/Turabian Style

Jayne Juan; Carlo Caligan; Maria Garcia; Jericho Mitra; Andres Mayol; Charlle Sy; Aristotle Ubando; Alvin Culaba. 2020. "Multi-Objective Optimization of an Integrated Algal and Sludge-Based Bioenergy Park and Wastewater Treatment System." Sustainability 12, no. 18: 7793.

Review
Published: 06 August 2020 in International Journal of Energy Research
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Sustainable energy production has been one of the contemporary concerns of society. In order to mitigate carbon dioxide emissions while generating the required demand for energy, various energy technologies, and production systems must be considered. In the consideration of different energy technologies, optimization is one of the important tools to optimally design energy systems. This study aims to analyze the progress of current research related to energy and sustainability that utilizes fuzzy optimization approach. Bibliometric methods based on the database of Web of Science core collection are used for the analysis. Of the 96 retrieved publications, 87% were journal articles. Analysis on the patterns for these articles were conducted such as highly cited articles, journals, subject categories, institutions, countries, and impact factor. The articles are evaluated into three categories such as technological, environmental, and economy and are comprehensively reviewed. The results showed a significant increase in publication related to fuzzy optimization in sustainability and energy technologies. The analysis showed China with 26 publications, which has the largest contribution in terms of the number of articles published. North China Electric Power University ranked as the number 1 institution with 10 publications. Based on the comprehensive analysis, fuzzy optimization showed significant results on technological, environmental, and economical factors. These findings help to identify hotspots in energy technology optimization for sustainability research. Similarly, the study gives useful inputs for selecting subtopics and strategy on publication related to fuzzy optimization on energy technologies.

ACS Style

Emmanuel R. Arriola; Aristotle T. Ubando; Wei‐Hsin Chen. A bibliometric review on the application of fuzzy optimization to sustainable energy technologies. International Journal of Energy Research 2020, 1 .

AMA Style

Emmanuel R. Arriola, Aristotle T. Ubando, Wei‐Hsin Chen. A bibliometric review on the application of fuzzy optimization to sustainable energy technologies. International Journal of Energy Research. 2020; ():1.

Chicago/Turabian Style

Emmanuel R. Arriola; Aristotle T. Ubando; Wei‐Hsin Chen. 2020. "A bibliometric review on the application of fuzzy optimization to sustainable energy technologies." International Journal of Energy Research , no. : 1.

Journal article
Published: 16 July 2020 in Journal of Cleaner Production
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The shift to a circular economy requires careful planning, the first step of which is to understand the drivers of the transition. There have been few papers in the literature that have analyzed and mapped interrelationships of these transition drivers from the perspective of different sectors. This work presents a methodological framework for mapping causality networks for macro-level transition towards circular economy based on sector perceptions. Fuzzy DEMATEL is used to allow linguistic inputs to be quantified. This procedure allows drivers to be characterized as causes or effects based on their position in the causality network. A case study presents the Philippines as a representative developing country for circular economy transition. The inputs of seventeen respondents from retail and trade, manufacturing, construction, water services, food services, electricity services, academic services, and health services were elicited through a survey. These responses were then aggregated into the industry and service sectors. The drivers considered were government support, company culture, social recognition, economic attractiveness, and information to practitioners. Results show that economic attractiveness and consumer demand are unanimously seen as the causal drivers. All sectors identify company culture as an effect driver. The findings also indicate varying perceptions among sectors. Although these findings apply specifically to the Philippines, this methodology itself can be used for mapping driver interrelationships of other countries and regions.

ACS Style

Ivan Henderson V. Gue; Michael Angelo B. Promentilla; Raymond R. Tan; Aristotle T. Ubando. Sector perception of circular economy driver interrelationships. Journal of Cleaner Production 2020, 276, 123204 .

AMA Style

Ivan Henderson V. Gue, Michael Angelo B. Promentilla, Raymond R. Tan, Aristotle T. Ubando. Sector perception of circular economy driver interrelationships. Journal of Cleaner Production. 2020; 276 ():123204.

Chicago/Turabian Style

Ivan Henderson V. Gue; Michael Angelo B. Promentilla; Raymond R. Tan; Aristotle T. Ubando. 2020. "Sector perception of circular economy driver interrelationships." Journal of Cleaner Production 276, no. : 123204.

Journal article
Published: 09 July 2020 in Engineering Failure Analysis
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Ball grid array (BGA) is one of the most innovative semiconductor packaging technologies which is capable of high input-output capacities while addressing handling and coplanarity compared with other packages. However, the BGA package is subjected to thermo-mechanical load which makes it susceptible to quality and reliability issues such as die crack. The occurrence of die crack is difficult to monitor as it is considered as an internal package issue and can be catastrophic to the electronic device which may lead to its failure. This study aims to investigate the various factors affecting die crack propagation using finite element analysis (FEA) model under thermo-mechanical loads. The energy release rate in the silicon die was used to quantify the propagation of die crack in the BGA package. The influence of the various factors on the propagation of die crack was determined through a design of experiment approach consisting of the definitive screening for initial factor screening, and response surface method through the central composite design. The results have shown that the die thickness, the glass transition temperature, the in-plane CTE of the substrate, and the initial crack length are the factors significantly affecting the die crack propagation in a BGA package. Moreover, at critical parameter conditions, the results have identified a critical crack length of 0.02236 mm. The study is aimed to benefit the research, design, development, assembly, and material engineers in the semiconductor industry providing insight to the die crack propagation of a BGA package.

ACS Style

Niño Rigo Emil G. Lim; Aristotle T. Ubando; Jeremias A. Gonzaga; Richard Raymond N. Dimagiba. Finite element analysis on the factors affecting die crack propagation in BGA under thermo-mechanical loading. Engineering Failure Analysis 2020, 116, 104717 .

AMA Style

Niño Rigo Emil G. Lim, Aristotle T. Ubando, Jeremias A. Gonzaga, Richard Raymond N. Dimagiba. Finite element analysis on the factors affecting die crack propagation in BGA under thermo-mechanical loading. Engineering Failure Analysis. 2020; 116 ():104717.

Chicago/Turabian Style

Niño Rigo Emil G. Lim; Aristotle T. Ubando; Jeremias A. Gonzaga; Richard Raymond N. Dimagiba. 2020. "Finite element analysis on the factors affecting die crack propagation in BGA under thermo-mechanical loading." Engineering Failure Analysis 116, no. : 104717.

Review
Published: 02 July 2020 in Clean Technologies and Environmental Policy
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Computational and statistical tools help manage the prevailing challenges of the 17 Sustainable Development Goals (SDGs) by providing meticulous understanding of contemporary issues. However, complex challenges are difficult to handle with conventional techniques, resulting to the need for more advanced methods. Artificial neural networks (ANNs) are often used as an advanced approach in modelling complex behaviour of systems. Evaluating the current utilization of ANNs helps researchers gauge their applicability to SDG-related issues. The gaps among the studied SDGs need to be addressed through a comprehensive survey of the state-of-the-art literature. Hence, this work reviews published journal articles on the application of ANNs in resolving issues of the SDGs. This review identifies the current trends and limitations of ANN for SDG, and discusses its prominent applications and field of utilization. Descriptive and content analysis of journal articles is performed for this review. Journal articles from the Scopus database reveal Clean Water and Sanitation, Affordable and Clean Energy, Sustainable Cities and Communities, and Responsible Consumption and Production are the most popular subject matter for modelling and forecasting. New innovative functions include feature selection, kriging, and simulation. The main contribution of this work is a comprehensive mapping of the current state of this area of research. This work aims to aid future researchers to recognize further possible uses of ANNs with respect to the SDGs.

ACS Style

Ivan Henderson V. Gue; Aristotle T. Ubando; Ming-Lang Tseng; Raymond R. Tan. Artificial neural networks for sustainable development: a critical review. Clean Technologies and Environmental Policy 2020, 22, 1449 -1465.

AMA Style

Ivan Henderson V. Gue, Aristotle T. Ubando, Ming-Lang Tseng, Raymond R. Tan. Artificial neural networks for sustainable development: a critical review. Clean Technologies and Environmental Policy. 2020; 22 (7):1449-1465.

Chicago/Turabian Style

Ivan Henderson V. Gue; Aristotle T. Ubando; Ming-Lang Tseng; Raymond R. Tan. 2020. "Artificial neural networks for sustainable development: a critical review." Clean Technologies and Environmental Policy 22, no. 7: 1449-1465.

Special issue research article
Published: 18 May 2020 in International Journal of Energy Research
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Mixed‐use buildings contribute to the sustainable development of cities by providing economic, environmental, and social benefits. Energy management of these buildings still remains a challenge due to their unpredictable energy consumption characteristics and the lack of design guidelines for energy efficiency and sustainability solutions. Energy consumption forecasting models have been crucial to the improvement of energy efficiency and sustainability of buildings but its application to mixed‐use buildings are limited. Hence, this study aims to develop a prediction model to characterize and forecast the energy consumption of mixed‐use buildings. Machine learning techniques are employed in the proposed prediction model which used k‐means algorithm for clustering and support vector machines for forecasting. The prediction model was developed and demonstrated on simulated energy consumption of 30 mixed‐use buildings from the open energy information database. The clustering results have found major differences in the consumption behavior of building clusters, especially on peaking characteristics. The differences were highlighted in terms of the domain knowledge on residential and commercial energy consumption behavior. The forecasting model results showed that the proposed integration of the clustering model was able to capture unique variations in the energy consumption of mixed‐use buildings. This led to a 46% decrease in the mean bias error and a 10% decrease in the coefficient of variation root mean square error wherein both indicators are commonly used in building energy modeling standards.

ACS Style

Alvin B. Culaba; Aaron Jules R. Del Rosario; Aristotle T. Ubando; Jo‐Shu Chang. Machine learning‐based energy consumption clustering and forecasting for mixed‐use buildings. International Journal of Energy Research 2020, 44, 9659 -9673.

AMA Style

Alvin B. Culaba, Aaron Jules R. Del Rosario, Aristotle T. Ubando, Jo‐Shu Chang. Machine learning‐based energy consumption clustering and forecasting for mixed‐use buildings. International Journal of Energy Research. 2020; 44 (12):9659-9673.

Chicago/Turabian Style

Alvin B. Culaba; Aaron Jules R. Del Rosario; Aristotle T. Ubando; Jo‐Shu Chang. 2020. "Machine learning‐based energy consumption clustering and forecasting for mixed‐use buildings." International Journal of Energy Research 44, no. 12: 9659-9673.

Special issue research article
Published: 23 April 2020 in International Journal of Energy Research
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The rise of mixed‐use buildings contributes to the sustainable development of cities but are still met with challenges in energy management due to the lack of energy efficiency and sustainability guidelines. The use of integrated renewable‐storage energy systems is a more beneficial solution to this problem over individual solutions; however, most design studies only focused on single‐type buildings. Thus, this study aims to optimally design an integrated energy system for mixed‐use buildings using HOMER Grid. The objective is to minimize the net present costs, subject to capacity limits, energy balances, and operational constraints. Economic metrics were used to evaluate and compare the proposed system to the varying design cases such as business‐as‐usual, stand‐alone renewable source, and stand‐alone energy storage. The case study considered a mixed‐use building in a tropical area, with a solar photovoltaic system as the renewable energy source and lithium‐ion battery as the energy storage system technology. The results show that the integrated system is the most financially attractive design case. It has a levelized cost of electricity of 0.1384 US$ kWh−1, which is significantly less than the 0.2580 US$ kWh−1 baseline. The system also provides electricity cost savings of 294 698 US$ y−1, excess electricity of 35 746 kWh, and carbon emission reduction of 550 tons annually for a mixed‐use building with daily average consumption of 4557‐kWh and 763‐kW peak demand.

ACS Style

Alvin B. Culaba; Aaron Jules R. Del Rosario; Aristotle T. Ubando; Jo‐Shu Chang. Optimal design of an integrated renewable‐storage energy system in a mixed‐use building. International Journal of Energy Research 2020, 44, 9646 -9658.

AMA Style

Alvin B. Culaba, Aaron Jules R. Del Rosario, Aristotle T. Ubando, Jo‐Shu Chang. Optimal design of an integrated renewable‐storage energy system in a mixed‐use building. International Journal of Energy Research. 2020; 44 (12):9646-9658.

Chicago/Turabian Style

Alvin B. Culaba; Aaron Jules R. Del Rosario; Aristotle T. Ubando; Jo‐Shu Chang. 2020. "Optimal design of an integrated renewable‐storage energy system in a mixed‐use building." International Journal of Energy Research 44, no. 12: 9646-9658.

Research article
Published: 04 February 2020 in International Journal of Energy Research
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Chemical‐looping combustion (CLC) provides a platform to generate energy streams while mitigating CO2 using iron oxide as a carrier of oxygen. Through the reduction process, iron oxide experiences phase transformation to ultimately produce metallic iron. To understand iron oxide reduction characteristics and optimally design the fuel reactor, kinetic and thermodynamic analyses were proposed, utilizing graphite. This study aims to evaluate the reduction behavior under the non‐isothermal process of various mixture ratios of hematite and graphite via thermogravimetric analysis with simultaneously evaluating evolved gases using a Fourier transform infrared spectrometer. The Coats‐Redfern model was employed to approximate the kinetic and thermodynamic parameters which assessed the different reaction mechanisms together with the distributed activation energy model (DAEM). The results revealed that the hematite‐to‐graphite ratio of 4:1 had the highest reduction degree and had three distinct peaks representing three iron oxide reduction phases. The zero‐order reaction mechanism agreed with the experimental results compared with other reaction models. The thermodynamic analysis showed an overall endothermic spontaneous reaction for the three phases which signified the direct reduction of the iron oxides. The DAEM result validated a stepwise reduction of iron oxides to metallic iron. The study aids the optimal design of the CLC fuel reactor for enhanced system performance.

ACS Style

Aristotle T. Ubando; Wei‐Hsin Chen; Pau‐Loke Show; Hwai Chyuan Ong. Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO 2 mitigation in chemical‐looping combustion. International Journal of Energy Research 2020, 44, 3865 -3882.

AMA Style

Aristotle T. Ubando, Wei‐Hsin Chen, Pau‐Loke Show, Hwai Chyuan Ong. Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO 2 mitigation in chemical‐looping combustion. International Journal of Energy Research. 2020; 44 (5):3865-3882.

Chicago/Turabian Style

Aristotle T. Ubando; Wei‐Hsin Chen; Pau‐Loke Show; Hwai Chyuan Ong. 2020. "Kinetic and thermodynamic analysis of iron oxide reduction by graphite for CO 2 mitigation in chemical‐looping combustion." International Journal of Energy Research 44, no. 5: 3865-3882.