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Records Added in December 2019
Records added in December 2019
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Showing records 398 to 422 of 423. [First] Page: 1 13 14 15 16 17 18 Last
Water-Gas Two-Phase Flow Behavior of Multi-Fractured Horizontal Wells in Shale Gas Reservoirs
Lei Li, Guanglong Sheng, Yuliang Su
December 3, 2019 (v1)
Keywords: flow behavior, fracturing horizontal wells, multi-porosity, shale gas reservoirs, water-gas two-phase flow
Hydraulic fracturing is a necessary method to develop shale gas reservoirs effectively and economically. However, the flow behavior in multi-porosity fractured reservoirs is difficult to characterize by conventional methods. In this paper, combined with apparent porosity/permeability model of organic matter, inorganic matter and induced fractures, considering the water film in unstimulated reservoir volume (USRV) region water and bulk water in effectively stimulated reservoir volume (ESRV) region, a multi-media water-gas two-phase flow model was established. The finite difference is used to solve the model and the water-gas two-phase flow behavior of multi-fractured horizontal wells is obtained. Mass transfer between different-scale media, the effects of pore pressure on reservoirs and fluid properties at different production stages were considered in this model. The influence of the dynamic reservoir physical parameters on flow behavior and gas production in multi-fractured horizontal... [more]
The Impact of Authorized Remanufacturing on Sustainable Remanufacturing
Xiqiang Xia, Cuixia Zhang
December 3, 2019 (v1)
Subject: Energy Policy
Keywords: authorized remanufacturing, game, remanufacturing, sustainability supply chain
Remanufacturing could effectively solve resource shortage and environment crisis and achieve sustainable development of the economy. The original equipment manufacturer (OEM) could not only focus on its core business (i.e., producing new products), but also get profit from remanufacturing through the intellectual property rights. Based on the authorized remanufacturing, the game model between a manufacturer and a remanufacturer was constructed. Based on the game model, the impact of authorized remanufacturing on sustainable remanufacturing is analysed, and the coordination mechanism between manufacturer and remanufacturer is given. The main results are as follows: the OEM could increase its profit and change its unfavourable market competition status by authorizing remanufacturing; a franchise contract could make the sustainability supply chain optimized; when the ratio of the environment effect is greater than a certain threshold, centralized decision-making could not only increase th... [more]
Comparison of Irregularity Indices of Several Dendrimers Structures
Dongming Zhao, Zahid Iqbal, Rida Irfan, Muhammad Anwar Chaudhry, Muhammad Ishaq, Muhammad Kamran Jamil, Asfand Fahad
December 3, 2019 (v1)
Subject: Materials
Keywords: dendrimers, irregularity indices, molecular graph
Irregularity indices are usually used for quantitative characterization of the topological structures of non-regular graphs. In numerous problems and applications, especially in the fields of chemistry and material engineering, it is useful to be aware of the irregularity of a molecular structure. Furthermore, the evaluation of the irregularity of graphs is valuable not only for quantitative structure-property relationship (QSPR) and quantitative structure-activity relationship (QSAR) studies but also for various physical and chemical properties, including entropy, enthalpy of vaporization, melting and boiling points, resistance, and toxicity. In this paper, we will restrict our attention to the computation and comparison of the irregularity measures of different classes of dendrimers. The four irregularity indices which we are going to investigate are σ irregularity index, the irregularity index by Albertson, the variance of vertex degrees, and the total irregularity index.
Gaussian Process Methodology for Multi-Frequency Marine Controlled-Source Electromagnetic Profile Estimation in Isotropic Medium
Muhammad Naeim Mohd Aris, Hanita Daud, Sarat Chandra Dass, Khairul Arifin Mohd Noh
December 3, 2019 (v1)
Keywords: computer experiment, electromagnetic profile estimation, Gaussian process, multiple frequency marine controlled-source electromagnetic technique, uncertainty quantification
The marine controlled-source electromagnetic (CSEM) technique is an application of electromagnetic (EM) waves to image the electrical resistivity of the subsurface underneath the seabed. The modeling of marine CSEM is a crucial and time-consuming task due to the complexity of its mathematical equations. Hence, high computational cost is incurred to solve the linear systems, especially for high-dimensional models. Addressing these problems, we propose Gaussian process (GP) calibrated with computer experiment outputs to estimate multi-frequency marine CSEM profiles at various hydrocarbon depths. This methodology utilizes prior information to provide beneficial EM profiles with uncertainty quantification in terms of variance (95% confidence interval). In this paper, prior marine CSEM information was generated through Computer Simulation Technology (CST) software at various observed hydrocarbon depths (250−2750 m with an increment of 250 m each) and different transmission frequencies (0.12... [more]
Rice Husk Biochars Modified with Magnetized Iron Oxides and Nano Zero Valent Iron for Decolorization of Dyeing Wastewater
Bao-Son Trinh, Phung T. K. Le, David Werner, Nguyen H. Phuong, Tran Le Luu
December 3, 2019 (v1)
Subject: Materials
Keywords: biochar, full-scale gasification, nano zero-valent iron, pyrolysis, rice husk
This study investigated if biochar, a low-cost carbon-rich material, can be modified with reactive materials for decolorization of dyeing wastewater. Two types of rice husk biochars were produced by using different processes of gasification and pyrolysis in limited air condition. The biochars were first magnetized and then modified with nano-scale zero-valent iron (nZVI) to achieve the final products of magnetic-nZVI biochars. Batch experiments were conducted to investigate the efficiency of the modified biochars for reducing color of the reactive dyes yellow (RY145), red (RR195), and blue (RB19) from dyeing solutions. Results showed that color removal efficiency of the modified biochars was significantly enhanced, achieving the values of 100% for RY145 and RR195 and ≥65% for RB19, while the effectiveness of the original biochar was significantly lower. In addition, with increasing dose of the modified biochars, the color removal efficiency increased accordingly. In contrast, when the... [more]
Advanced Methodologies for Biomass Supply Chain Planning
Duy Nguyen Duc, Narameth Nananukul
December 3, 2019 (v1)
Keywords: biomass supply chain planning, hybrid methodology, parameter search optimization, simulation-based optimization, stochastic programming
Renewable energy resources have received increasing attention due to environmental concerns. Biomass, one of the most important renewable energy resources, is abundant in agricultural-based countries. Typically, the biomass supply chain is large due to the huge amount of relevant data required for building the model. As a result, using a standard optimization package to determine the solution for the biomass supply chain model might not be practical. In this study, the focus is on developing and applying advanced methodologies that can be used to determine a solution for the biomass supply chain model efficiently. The decisions related to plant selection, and distribution of biomass from suppliers to plants require optimization. The methodologies considered in this research are based on stochastic programming, parameter search, and simulation-based optimization. Computational results and managerial insights based on case studies from different regions of Vietnam are provided. The resul... [more]
An Overview of Temperature Issues in Microwave-Assisted Pyrolysis
Mattia Bartoli, Marco Frediani, Cedric Briens, Franco Berruti, Luca Rosi
December 3, 2019 (v1)
Keywords: microwave, pyrolysis, temperature control
Microwave-assisted pyrolysis is a promising thermochemical technique to convert waste polymers and biomass into raw chemicals and fuels. However, this process involves several issues related to the interactions between materials and microwaves. Consequently, the control of temperature during microwave-assisted pyrolysis is a hard task both for measurement and uniformity during the overall pyrolytic run. In this review, we introduce some of the main theoretical aspects of the microwaves−materials interactions alongside the issues related to microwave pyrolytic processability of materials.
Fine-Tuning Meta-Heuristic Algorithm for Global Optimization
Ziyad T. Allawi, Ibraheem Kasim Ibraheem, Amjad J. Humaidi
December 3, 2019 (v1)
Subject: Optimization
Keywords: benchmark functions, exploitation, exploration, global minimum, global optimization, local minimum, meta-heuristics, swarm intelligence
This paper proposes a novel meta-heuristic optimization algorithm called the fine-tuning meta-heuristic algorithm (FTMA) for solving global optimization problems. In this algorithm, the solutions are fine-tuned using the fundamental steps in meta-heuristic optimization, namely, exploration, exploitation, and randomization, in such a way that if one step improves the solution, then it is unnecessary to execute the remaining steps. The performance of the proposed FTMA has been compared with that of five other optimization algorithms over ten benchmark test functions. Nine of them are well-known and already exist in the literature, while the tenth one is proposed by the authors and introduced in this article. One test trial was shown to check the performance of each algorithm, and the other test for 30 trials to measure the statistical results of the performance of the proposed algorithm against the others. Results confirm that the proposed FTMA global optimization algorithm has a competi... [more]
Method of Moments Applied to Most-Likely High-Temperature Free-Radical Polymerization Reactions
Hossein Riazi, Ahmad Arabi Shamsabadi, Michael C. Grady, Andrew M. Rappe, Masoud Soroush
December 3, 2019 (v1)
Keywords: free-radical polymerization, high-temperature polymerization, method of moments, methyl acrylate, thermal polymerization
Many widely-used polymers are made via free-radical polymerization. Mathematical models of polymerization reactors have many applications such as reactor design, operation, and intensification. The method of moments has been utilized extensively for many decades to derive rate equations needed to predict polymer bulk properties. In this article, for a comprehensive list consisting of more than 40 different reactions that are most likely to occur in high-temperature free-radical homopolymerization, moment rate equations are derived methodically. Three types of radicals—secondary radicals, tertiary radicals formed through backbiting reactions, and tertiary radicals produced by intermolecular chain transfer to polymer reactions—are accounted for. The former tertiary radicals generate short-chain branches, while the latter ones produce long-chain branches. In addition, two types of dead polymer chains, saturated and unsaturated, are considered. Using a step-by-step approach based on the me... [more]
An Intensified Reactive Separation Process for Bio-Jet Diesel Production
Miriam García-Sánchez, Mauricio Sales-Cruz, Teresa Lopez-Arenas, Tomás Viveros-García, Eduardo S. Pérez-Cisneros
December 3, 2019 (v1)
Keywords: bio-jet diesel, co-hydrotreating, hydrodeoxigenation, hydrodesulphurisation, Reactive Distillation
An intensified three-step reaction-separation process for the production of bio-jet diesel from tryglycerides and petro-diesel mixtures is proposed. The intensified reaction-separation process considers three sequentially connected sections: (1) a triglyceride hydrolysis section with a catalytic heterogeneous reactor, which is used to convert the triglycerides of the vegetable oils into the resultant fatty acids. The separation of the pure fatty acid from glycerol and water is performed by a three-phase flash drum and two conventional distillation columns; (2) a co-hydrotreating section with a reactive distillation column used to perform simultaneously the deep hydrodesulphurisation (HDS) of petro-diesel and the hydrodeoxigenation (HDO), decarbonylation and decarboxylation of the fatty acids; and (3) an isomerization-cracking section with a hydrogenation catalytic reactor coupled with a two-phase flash drum is used to produce bio-jet diesel with the suitable fuel features required by t... [more]
Simulation and Experimental Study of a Single Fixed-Bed Model of Nitrogen Gas Generator Working by Pressure Swing Adsorption
Pham Van Chinh, Nguyen Tuan Hieu, Vu Dinh Tien, Tan-Y Nguyen, Hoang Nam Nguyen, Ngo Thi Anh, Do Van Thom
December 3, 2019 (v1)
Keywords: Adsorption, carbon molecular sieve (CMS), nitrogen, nitrogen generator, pressure swing adsorption (PSA)
Nitrogen is an inert gas available in the air and is widely used in industry and food storage technology. Commonly, it is separated by air refrigerant liquefaction and fractional distillation techniques based on different boiling temperatures of components in the mixed air. Currently, selective adsorption techniques by molecular sieve materials are studied and applied to separate gases based on their molecular size. In this paper, we simulate and investigate the effect parameters in a single fixed-bed model of a nitrogen gas generator using carbon molecular sieves, following pressure swing adsorption. This study aims to identify the effect of changing parameters so as to select the optimal working conditions of a single fixed-bed model, used as a basis for equipment optimization. This equipment was designed, manufactured, and installed at the Institute of Technology, General Department of Defense Industry, Vietnam to investigate, simulate, and optimize the industrial scale-up.
Effects of Conventional Flotation Frothers on the Population of Mesophilic Microorganisms in Different Cultures
Mohammad Jafari, Mehdi Golzadeh, Sied Ziaedin Shafaei, Hadi Abdollahi, Mahdi Gharabaghi, Saeed Chehreh Chelgani
December 3, 2019 (v1)
Subject: Biosystems
Keywords: bioleaching, flotation, frother, Machine Learning, mixed culture
Bioleaching is an environment-friendly and low-investment process for the extraction of metals from flotation concentrate. Surfactants such as collectors and frothers are widely used in the flotation process. These chemical reagents may have inhibitory effects on the activity of microorganisms through a bioleaching process; however, there is no report indicating influences of reagents on the activity of microorganisms in the mixed culture which is mostly used in the industry. In this investigation, influences of typical flotation frothers (methyl isobutyl carbinol and pine oil) in different concentrations (0.01, 0.10, and 1.00 g/L) were examined on activates of bacteria in the mesophilic mixed culture (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Acidithiobacillus thiooxidans). For comparison purposes, experiments were repeated by pure cultures of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in the same conditions. Results indicated that increasing... [more]
Characterizing the Suitability of Granular Fe0 for the Water Treatment Industry
Rui Hu, Xuesong Cui, Minhui Xiao, Pengxiang Qiu, Mesia Lufingo, Willis Gwenzi, Chicgoua Noubactep
December 3, 2019 (v1)
Subject: Materials
Keywords: 1,10-phenanthroline, ethylenediaminetetraacetic acid, intrinsic reactivity, material selection, quality control, zero-valent iron
There is a burgeoning interest in reliably characterizing the intrinsic reactivity of metallic iron materials (Fe0) or zero-valent iron materials (ZVI) used in the water treatment industry. The present work is a contribution to a science-based selection of Fe0 for water treatment. A total of eight (8) granular ZVI materials (ZVI1 to ZVI8) were tested. Fe0 dissolution in ethylenediaminetetraacetic acid (EDTA test) and 1,10-Phenanthroline (Phen test) is characterized in parallel experiments for up to 250 h (10 days). 50 mL of each solution and 0.1 g of each Fe0 material are equilibrated in quiescent batch experiments using 2 mM EDTA or Phen. Results indicated a far higher extent of iron dissolution in EDTA than in Phen under the experimental conditions. The tested materials could be grouped into three reactivity classes: (i) low (ZVI4, ZVI6, ZVI7, and ZVI8), (ii) moderate (ZVI1 and ZVI5) and (iii) high (ZVI2 and ZVI3). The order of reactivity was the same for both tests: ZVI2 ≅ ZVI3 > ZV... [more]
Bioenvironmental Zonal Controlling of Incubated Avian Embryo Using Localised Infrared Heating
Ali Youssef, Tomas Norton, Daniel Berckmans
December 3, 2019 (v1)
Keywords: bioenvironmental control, Dynamic Modelling, model-predictive controller, zonal controlling
The main objective of any bioenvironmental controller is to create favourable bioenvironmental conditions around the living-system. In industrial incubation practice of chicken embryo, it is sometimes difficult to fill large incubators with uniform eggs, which leads to suboptimal results. The ideal incubation solution is a machine that is capable of coping with all sorts of variabilities in eggs. This can be realised in practice by creating different zones of different environmental conditions within the same machine. In the present study, a two-levels controller was designed and implemented to combine both convective and radiative heating to incubate eggs. On the higher level, three model-predictive-control (MPC) constrained controllers were developed to regulate the power applied to nine IR-radiators divided into three zones based on continuous feedback of the eggshell temperatures in each zone. On the lower level, a PID controller was used to maintain the air temperature within an e... [more]
The Study of a Multicriteria Decision Making Model for Wave Power Plant Location Selection in Vietnam
Chia-Nan Wang, Nguyen Van Thanh, Chih-Chiang Su
December 3, 2019 (v1)
Keywords: FANP, fuzzy logics, MCDM, Renewable and Sustainable Energy, TOPSIS, Wave Energy
With about a 7% average annual economic growth rate in Vietnam, the demand for electricity production is increasing, and, with more than 3000 km of coastline, the country has great potential for developing wave energy sources to meet such electricity production. This energy source, also known as renewable energy, comes from tides, wind, heat differences, flows, and waves. Both wind and wave energy are considered to have the most potential for energy sources in Vietnam. Just as hydropower projects are controversial due to depleting water resources and regulating floods, nuclear power projects cause safety concerns. To overcome this problem, Vietnamese scientists are considering using abundant wave energy resources for electricity. Nowadays, the ocean energy sector offers many new technologies to help minimize carbon dioxide emissions (CO2) in the living environment. Further, many countries already have wave power plants. In this research, an integrated model, combining the fuzzy analyti... [more]
Experimental and Numerical Simulation Study on Co-Incineration of Solid and Liquid Wastes for Green Production of Pesticides
Bin Zhang, Jinjie He, Chengming Hu, Wei Chen
December 3, 2019 (v1)
Keywords: co-incineration, emission reduction, green production, rotary kiln, waste disposal
A large amount of solid and liquid waste is produced in pesticide production. It is necessary to adopt appropriate disposal processes to reduce pollutant emissions. A co-incineration scheme for mixing multi-component wastes in a rotary kiln was proposed for waste disposal from pesticide production. According to the daily output of solid and liquid wastes, the proportion of mixing was determined. An experiment of the co-incineration of solid and liquid wastes was established. Experimental results showed that the mixed waste could be completely disposed at 850 °C, and the residence time in the kiln exceeded 1 h. A model method for mixture and diesel oil-assisted combustion was proposed. Numerical simulation was performed to predict the granular motion and reveal the combustion interactions of the co-incineration of mixed wastes in the rotary kiln. Simulation results reproduced movements, such as rolling and cascading, and obtained the optimum rotational speed and diesel oil flow for the... [more]
An Integration Method Using Kernel Principal Component Analysis and Cascade Support Vector Data Description for Pipeline Leak Detection with Multiple Operating Modes
Mengfei Zhou, Qiang Zhang, Yunwen Liu, Xiaofang Sun, Yijun Cai, Haitian Pan
December 3, 2019 (v1)
Keywords: cascade support vector data description, K-means, kernel principal component analysis, leak detection, multiple operating modes
Pipelines are one of the most efficient and economical methods of transporting fluids, such as oil, natural gas, and water. However, pipelines are often subject to leakage due to pipe corrosion, pipe aging, pipe weld defects, or damage by a third-party, resulting in huge economic losses and environmental degradation. Therefore, effective pipeline leak detection methods are important research issues to ensure pipeline integrity management and accident prevention. The conventional methods for pipeline leak detection generally need to extract the features of leak signal to establish a leak detection model. However, it is difficult to obtain actual leakage signal data samples in most applications. In addition, the operating modes of pipeline fluid transportation process often have frequent changes, such as regulating valves and pump operation. Aiming at these issues, this paper proposes a hybrid intelligent method that integrates kernel principal component analysis (KPCA) and cascade suppo... [more]
Effect of Cellulosic Waste Derived Filler on the Biodegradation and Thermal Properties of HDPE and PLA Composites
Alessia Quitadamo, Valerie Massardier, Valeria Iovine, Ahmed Belhadj, Rémy Bayard, Marco Valente
December 3, 2019 (v1)
Subject: Materials
Keywords: bio-derived polymer, biodegradation, composites
Composites with high density polyethylene (HDPE) and poly(lactic) acid (PLA) matrix have been tested to analyze the effect of natural fillers (wood flour, recycled wastepaper and a mix of both fillers) and temperature on polymer degradation. Composting tests have been performed in both mesophilic (35 °C) and thermophilic (58 °C) conditions. Degradation development has been evaluated through mass variation, thermogravimetric analysis and differential scanning calorimetry. HDPE, as expected, did not display any relevant variation, confirming its stability under our composting conditions. PLA is sensibly influenced by temperature and humidity, with higher reduction of Mw when composting is performed at 58 °C. Natural fillers seem to influence degradation process of composites, already at 35 °C. In fact, degradation of fillers at 35 °C allows a mass reduction during composting of composites, while neat PLA do not display any variation.
Implementation of Production Process Standardization—A Case Study of a Publishing Company from the SMEs Sector
Arturo Realyvásquez-Vargas, Francisco Javier Flor-Moltalvo, Julio Blanco-Fernández, Joanna Denisse Sandoval-Quintanilla, Emilio Jiménez-Macías, Jorge Luis García-Alcaraz
December 3, 2019 (v1)
Keywords: inefficient movements, line balancing, optimization of productivity, work standardization, workstations redesign
This paper reports a case study using a standardization process for increasing efficiency and a better optimization of resources in a printing company with 150 operators having manual and mechanical tasks in the box assembly department along with four production lines. The current capacity is 350 boxes per day, while the demand is 650 units, where the company is expected to pay large sums for overtime. Using work standardization, studying worker movements, timing, and workstations redesign, the main goal was to increase the efficiency and productivity indexes. After applying those tools, the inefficient movements in operators decreased from 230 to 78, eliminating 66% of the unnecessary movements, as well as the standard time in a workstation decreased from 244 to 199 s (18.44%) per each assembled box, and the production rate increased by 63.2%, that is, 229 units per assembly line a day, where overtime was reduced to zero.
BISSO: Biomass Interface for Superstructure Simulation and Optimization
Franco Mangone, Jimena Ferreira, Ana I. Torres
December 3, 2019 (v1)
Keywords: biomass conversion processes, biorefineries, optimization web-based tool
This paper presents a web-based tool for the optimization of biomass-to-chemicals processing pathways. The tool provides a user-friendly grpahical user interface (GUI) for building a process superstructure, offers the possibility of uploading data from Aspen Plus simulations and generates an optimization code to find the pathway that minimizes the annualized costs or maximizes the net present value. A processing pathway from residues to lactic acid is used to discuss and illustrate the main features of the tool.
Enhancement of Bacillus subtilis Growth and Sporulation by Two-Stage Solid-State Fermentation Strategy
Zhi-Min Zhao, Jun-Ting Xi, Ji-Fei Xu, Li-Tong Ma, Ji Zhao
December 3, 2019 (v1)
Subject: Biosystems
Keywords: agro-industrial residues, Bacillus subtilis, low-field nuclear magnetic resonance (LF-NMR), microbial ecological agents, solid-state fermentation, sporulation
Two-stage solid-state fermentation strategy was exploited and systematically optimized to enhance Bacillus subtilis growth and sporulation for increasing effective cell number in B. subtilis microbial ecological agents. The first stage focused on improving cell growth followed by the second stage aiming to enhance both cell growth and sporulation. The optimal fermentation condition was that temperature changed from 37 °C to 47 °C at a fermentation time of 48 h and Mn2+ content in medium was 4.9 mg MnSO4/g dry medium. Solid medium properties were improved by the optimal two-stage fermentation. HPLC results demonstrated that glucose utilization was facilitated and low-field nuclear magnetic resonance (LF-NMR) results showed that more active sites in medium for microbial cells were generated during the optimal two-stage fermentation. Moreover, microbial growth and sporulation were enhanced simultaneously during the second stage of fermentation through delaying microbial decline phase and... [more]
What Is the Right Innovation Type for Your Industry? Evidence from Chemical Firms in Korea
Jaeho Shin, Yeongjun Kim, Hongsuk Yang, Changhee Kim
December 3, 2019 (v1)
Keywords: chemical industry, data envelopment analysis, efficiency measurement, innovation efficiency, process innovation, product innovation
The literature has two different perspectives on which innovation types should be implemented to achieve innovation performance; some argue that they should pursue process-oriented innovation, while others maintain that both product- and process-oriented innovation should be performed. Though innovation efficiency should be measured, which takes both input and output variables into account, the research so far has been measured only with the performance of the innovation. Accordingly, this study identifies which innovation type is the most advantageous in terms of innovation efficiency for the chemical firms. We use data of 64 Korean chemical companies from a 2016 Korean innovation survey and perform data envelopment analysis to calculate innovation efficiency. Kruskal−Wallis one-way ANOVA and bootstrap DEA were also conducted to compare the difference of innovation efficiency among groups, depending on which innovation types are oriented. The result shows that focusing on process inno... [more]
Economic Analysis of Cellulosic Ethanol Production from Sugarcane Bagasse Using a Sequential Deacetylation, Hot Water and Disk-Refining Pretreatment
Ming-Hsun Cheng, Zhaoqin Wang, Bruce S. Dien, Patricia J. W. Slininger, Vijay Singh
December 3, 2019 (v1)
Keywords: minimum ethanol selling price, production cost, sequential three-stage pretreatment, simultaneous saccharification and co-fermentation (SScF), sugarcane bagasse
A new process for conversion of sugarcane bagasse to ethanol was analyzed for production costs and energy consumption using experimental results. The process includes a sequential three-stage deacetylation, hot water, and disk-refining pretreatment and a commercial glucose-xylose fermenting S. cerevisiae strain. The simultaneous saccharification and co-fermentation (SScF) step used was investigated at two solids loadings: 10% and 16% w/w. Additionally, a sensitivity analysis was conducted for the major operating parameters. The minimum ethanol selling price (MESP) varied between $4.91and $4.52/gal ethanol. The higher SScF solids loading (16%) reduced the total operating, utilities, and production costs by 9.5%, 15.6%, and 5.6%, respectively. Other important factors in determining selling price were costs for fermentation medium and enzymes (e.g., cellulases). Hence, these findings support operating at high solids and producing enzymes onsite as strategies to minimize MESP.
Leaching of Organic Toxic Compounds from PVC Water Pipes in Medina Al-Munawarah, Kingdom of Saudi Arabia
Muhammad Mansoor Shaikh, Marlia Mohd Hanafiah, Alfarooq O. Basheer
December 3, 2019 (v1)
Subject: Materials
Keywords: drinking water, polyvinylchloride (PVC), solid phase extraction (SPE), volatile compounds
It is well established that the use of synthetic material in water pipes significantly affects the quality of domestic water, especially trace organics that are leached through with the flow of water. In the present study, the migration of volatile organic compounds (VOCs) from water pipes manufactured of polyvinyl chloride (PVC) has been investigated using static laboratory conditions and in residential areas. The contact of deionized water with various PVC pipes for three successive test periods of 24, 48, and 72 h duration has been made. Twenty water samples were collected from houses within Medina Al-Munawarah residential area and were analyzed by using solid phase extraction, followed by high resolution gas chromatography with flame ionized detector (GC-FID). The presence of carbon tetrachloride (CTC), toluene, chloroform, styrene, o-xylene, bromoform (BF), dibromomethane (DBM), cis-1,3-dichloropropane (Cis-1,3-DCP), and trans-1,3-dichloropropane (Trans-1,3-DCP) was initially conf... [more]
Using Parallel Genetic Algorithms for Estimating Model Parameters in Complex Reactive Transport Problems
Jagadish Torlapati, T. Prabhakar Clement
December 3, 2019 (v1)
Keywords: genetic algorithms, groundwater, parallel computing, parallel genetic algorithm, reactive transport, water quality
In this study, we present the details of an optimization method for parameter estimation of one-dimensional groundwater reactive transport problems using a parallel genetic algorithm (PGA). The performance of the PGA was tested with two problems that had published analytical solutions and two problems with published numerical solutions. The optimization model was provided with the published experimental results and reasonable bounds for the unknown kinetic reaction parameters as inputs. Benchmarking results indicate that the PGA estimated parameters that are close to the published parameters and it also predicted the observed trends well for all four problems. Also, OpenMP FORTRAN parallel constructs were used to demonstrate the speedup of the code on an Intel quad-core desktop computer. The parallel code showed a linear speedup with an increasing number of processors. Furthermore, the performance of the underlying optimization algorithm was tested to evaluate its sensitivity to the va... [more]
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