Manila, Philippines
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Functionalization of zigzag graphene nanoribbon (ZGNR) segment containing 120 C atoms with pyridine (3NV-ZGNR) defects was investigated on the basis of density-functional theory (DFT) calculations, results show that edge-modified ZGNRs by Sc can adsorb multiple hydrogen molecules in a quasi-molecular fashion, thereby can be a potential candidate for hydrogen storage. The stability of Sc functionalization is dictated by a strong binding energy, suggesting a reduction of clustering of metal atoms over the metal-decorated ZGNR.

Tan R.R.,De La Salle University - Manila
Applied Energy | Year: 2011

The concept of inoperability was originally introduced as a means of quantifying risk in systems comprised of interdependent subsystems, using a modified input-output framework. This paper describes a novel robust optimization model for energy planning with inoperability constraints. The formulation is based on the established source-sink framework, which has been used extensively for energy planning applications under various environmental footprint constraints. The proposed model determines the optimal allocation of various energy sources within a system to corresponding energy sinks or demands, while ensuring that inoperability limits of the latter are satisfied for multiple enumerated scenarios. The basic formulation results in a linear program (LP), while a mixed integer linear programming (MILP) extension is also described. In either case, a globally optimal solution can be easily determined if one exists. Illustrative case studies are then given to demonstrate this new method. © 2011.

Razon L.F.,De La Salle University - Manila | Tan R.R.,De La Salle University - Manila
Applied Energy | Year: 2011

Microalgae have been proposed as possible alternative feedstocks for the production of biodiesel because of their high photosynthetic efficiency. The high energy input required for microalgal culture and oil extraction may negate this advantage, however. There is a need to determine whether microalgal biodiesel can deliver more energy than is required to produce it. In this work, net energy analysis was done on systems to produce biodiesel and biogas from two microalgae: Haematococcus pluvialis and Nannochloropsis. Even with very optimistic assumptions regarding the performance of processing units, the results show a large energy deficit for both systems, due mainly to the energy required to culture and dry the microalgae or to disrupt the cell. Some energy savings may be realized from eliminating the fertilizer by the use of wastewater or, in the case of H. pluvialis, recycling some of the algal biomass to eliminate the need for a photobioreactor, but these are insufficient to completely eliminate the deficit. Recommendations are made to develop wet extraction and transesterification technology to make microalgal biodiesel systems viable from an energy standpoint. © 2010 Elsevier Ltd.

Tseng M.-L.,University of Business and Technology | Chiu A.S.F.,De La Salle University - Manila
Journal of Cleaner Production | Year: 2013

There has been an increasing interest towards firms' environmental sustainability activities to improve practices in their supply chain. Stringent environmental regulations in Europe and US challenge manufacturers to comply with these without losing their competitiveness. This study illustrates the case of a printed circuit board manufacturer in Taiwan that seeks to implement green supply chain management (GSCM) and selects a green supplier to meet its requirements. Choosing the suitable supplier is a key strategic direction in eliminating environmental impact on supply chain management for manufacturing firms. The firm's criteria and supplier selection need to be unified as a system to improve the firm's performance. This study identified the appropriate environmental and non-environmental GSCM criteria for the case firm and developed the following selection method: (i) evaluate the weights of criteria and alternatives as described both by qualitative and quantitative information; and (ii) rank alternative suppliers using a grey relational analysis. The result shows Alternative 3 ranks first among the four evaluated suppliers and demonstrated strong performance in the top three important criteria, namely, environmental management systems, profitability of supplier and relationship supplier closeness. Additionally, the perception weights on criteria itself are same as the most top five in weighted alternative. © 2010 Elsevier Ltd. All rights reserved.

Tan R.R.,De La Salle University - Manila
International Journal of Life Cycle Assessment | Year: 2010

Background, aim, and scope: Propagation of parametric uncertainty in life cycle inventory (LCI) models is usually performed based on probabilistic Monte Carlo techniques. However, alternative approaches using interval or fuzzy numbers have been proposed based on the argument that these provide a better reflection of epistemological uncertainties inherent in some process data. Recent progress has been made to integrate fuzzy arithmetic into matrix-based LCI using decomposition into α-cut intervals. However, the proposed technique implicitly assumes that the lower bounds of the technology matrix elements give the highest inventory results, and vice versa, without providing rigorous proof. Materials and methods: This paper provides formal proof of the validity of the assumptions made in that paper using a formula derived in 1950. It is shown that an increase in the numerical value of an element of the technology matrix A results in a decrease of the corresponding element of the inverted matrix A -1, provided that the latter is non-negative. Results: It thus follows that the assumption used in fuzzy uncertainty propagation using matrix-based LCI is valid when A -1 does not contain negative elements. Discussion: In practice, this condition is satisfied by feasible life cycle systems whose component processes have positive scaling factors. However, when avoided processes are used in order to account for the presence of multifunctional processes, this condition will be violated. We then provide some guidelines to ensure that the necessary conditions for fuzzy propagation are met by an LCI model. Conclusions: The arguments presented here thus provide rigorous proof that the algorithm developed for fuzzy matrix-based LCI is valid under specified conditions, namely when the inverse of the technology matrix is non-negative. Recommendations and perspectives: This paper thus gives the conditions for which computationally efficient propagation of uncertainties in fuzzy LCI models is strictly valid. © 2010 The Author(s).

Soriano C.R.R.,De La Salle University - Manila
Information Society | Year: 2016

This article analyzes the transmedia strategies of three ethnic minority activist organizations in the Philippines: Cordillera Peoples Alliance, Tebtebba, and the Moro Islamic Liberation Front. The fieldwork entailed interviews with leaders of these organizations and their media teams, scholars who study these movements, and social commentators. The analysis shows the complexities of identity construction in the age of spreadable media and the importance of transmedia literacy for activists who have to navigate these complexities to effectively advance their cause. © 2016, Published with license by Taylor & Francis.

Aviso K.B.,De La Salle University - Manila
Process Safety and Environmental Protection | Year: 2014

The field of industrial ecology promotes the establishment of resource exchange networks in eco-industrial parks (EIPs) as an approach toward resource conservation. Previous studies have shown that full blown resource integration can be encouraged through the exchange of common utilities such as energy and water. Different approaches such as mathematical programming, pinch analysis and game theory have been used to identify the optimal network designs, which can simultaneously reduce the utilization of freshwater resources and the generation of wastewater streams. Since water exchange in an EIP involves multiple independently operating plants, information exchange between the participants is not completely transparent and multiple future scenarios are expected to happen as the fate and plans of other participants are not completely divulged. These future scenarios may bring about changes in the capacity or characteristic of industrial processes and may also involve the entry of additional companies and the closure of previously operating ones. Such aspects have not been fully addressed in previous studies. A robust optimization model is thus developed in this work to determine the optimal network design which can effectively operate in anticipation of multiple probable scenarios. Case studies are solved to demonstrate the capability of the model. © 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Camacho D.H.,De La Salle University - Manila | Guan Z.,University of California at Irvine
Chemical Communications | Year: 2010

The innovation of polyolefin with unique architecture, composition and topology continues to inspire polymer chemists. An exciting recent direction in the polyolefin field is the design of new catalysts based on late-transition metals. In this review, we highlight recent developments in rationally designing late-transition metal catalysts for olefin polymerization. The examples described in this review showcase the power of the design of well-defined late-metal catalysts for tailored polyolefin synthesis, which may usher in a new era in the polymer industry. © 2010 The Royal Society of Chemistry.

In this paper, an alternative means for nitrogen fixation that may consume less energy and release less greenhouse gases than the Haber-Bosch process is explored. A life-cycle assessment was conducted on a process to: culture the cyanobacterium, Anabaena sp. ATCC 33047, in open ponds; harvest the biomass and exopolysaccharides and convert these to biogas; strip and convert the ammonia from the biogas residue to ammonium sulfate; dry the ammonium sulfate solution to ammonium sulfate crystals and transport the finished product. The results suggest that substantial reductions in non-renewable energy use and greenhouse gas emissions may be realized. The study opens the possibility that Haber-Bosch ammonia may be replaced with ammonia from a biomass process which simultaneously generates renewable energy. The process is intrinsically safer than the Haber-Bosch process. However, there are trade-offs in terms of land use and possibly, water. © 2011 Elsevier Ltd.

Tan R.R.,De La Salle University - Manila
Industrial and Engineering Chemistry Research | Year: 2011

Source-sink problems occur in various process systems engineering applications, such as the design of water reuse systems and resource conservation networks. Such problems may be solved using alternative approaches, including graphical pinch analysis and linear programming. In most cases, it is normally assumed that the stream flow rates and quality levels are deterministic. This paper presents a fuzzy mathematical programming model for the synthesis of water networks when the model parameters exhibit fuzzy uncertainties. The modeling approach is illustrated for three water network case studies adapted from literature. These illustrative examples cover concentration- and property-based stream quality indices, as well as single- and multiple-plant water integration. © 2010 American Chemical Society.

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