Records Added in October 2019
Records added in October 2019
Change year: 2018 | 2019
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Showing records 1 to 25 of 36. [First] Page: 1 2 Last
Numerical Simulation of Effects of Different Operational Parameters on the Carbon Solution Loss Ratio of Coke inside Blast Furnace
Mingyin Kou, Heng Zhou, Li Pang Wang, Zhibin Hong, Shun Yao, Haifa Xu, Shengli Wu
October 26, 2019 (v1)
Keywords: blast furnace, carbon solution loss, coke, numerical simulation
Carbon solution loss reaction of coke gasification is one of the most important reasons for coke deterioration and degradation in a blast furnace. It also affects the permeability of gas and fluids, as well as stable working conditions. In this paper, a three dimensional model is established based on the operational parameters of blast furnace B in Bayi Steel. The model is then used to calculate the effects of oxygen enrichment, coke oven gas injection, and steel scrap charging on the carbon solution loss ratio of coke in the blast furnace. Results show that the carbon solution loss ratio of coke gasification for blast furnace B is almost 20% since the results of a model are probably only indicative. The oxygen enrichment and the addition of steel scrap can reduce the carbon solution loss ratio with little effect on the working condition. However, coke oven gas injection increases the carbon solution loss ratio. Therefore, coke oven gas should not be injected into the blast furnace unl... [more]
Modeling and Simulation of Crystallization of Metal−Organic Frameworks
Anish V. Dighe, Roshan Y. Nemade, Meenesh R. Singh
October 26, 2019 (v1)
Keywords: mechanism of MOF synthesis, modeling and simulation of MOF synthesis, population balance modeling
Metal−organic frameworks (MOFs) are the porous, crystalline structures made of metal−ligands and organic linkers that have applications in gas storage, gas separation, and catalysis. Several experimental and computational tools have been developed over the past decade to investigate the performance of MOFs for such applications. However, the experimental synthesis of MOFs is still empirical and requires trial and error to produce desired structures, which is due to a limited understanding of the mechanism and factors affecting the crystallization of MOFs. Here, we show for the first time a comprehensive kinetic model coupled with population balance model to elucidate the mechanism of MOF synthesis and to estimate size distribution of MOFs growing in a solution of metal−ligand and organic linker. The oligomerization reactions involving metal−ligand and organic linker produce secondary building units (SBUs), which then aggregate slowly to yield MOFs. The formation of secondary building u... [more]
Mathematical Modeling and Simulation on the Stimulation Interactions in Coalbed Methane Thermal Recovery
Teng Teng, Yingheng Wang, Xiang He, Pengfei Chen
October 26, 2019 (v1)
Keywords: coalbed methane thermal recovery, heat-gas-coal model, modeling and simulation, thermal stimulation interaction
Heat stimulation of coalbed methane (CBM) reservoirs has remarkable promotion to gas desorption that enhances gas recovery. However, coalbed deformation, methane delivery and heat transport interplay each other during the stimulation process. This paper experimentally validated the evolutions of gas sorption and coal permeability under variable temperature. Then, a completely coupled heat-gas-coal model was theoretically developed and applied to a computational simulation of CBM thermal recovery based on a finite element approach of COMSOL with MATLAB. Modeling and simulation results show that: Although different heat-gas-coal interactions have different effects on CBM recovery, thermal stimulation of coalbed can promote methane production effectively. However, CBM thermal recovery needs a forerunner heating time before the apparent enhancement of production. The modeling and simulation results may improve the current cognitions of CBM thermal recovery.
High Pressure Injection of Chemicals in a Gravel Beach
Xiaolong Geng, Ali Abdollahi-Nasab, Chunjiang An, Zhi Chen, Kenneth Lee, Michel C. Boufadel
October 26, 2019 (v1)
Subject: Other
Keywords: bioremediation, Exxon Valdez oil spill, high pressure injection, tidal beach, tracer study
The remediation of beaches contaminated with oil includes the application of surfactants and/or the application of amendments to enhance oil biodegradation (i.e., bioremediation). This study focused on evaluating the practicability of the high pressure injection (HPI) of dissolved chemicals into the subsurface of a lentic Alaskan beach subjected to a 5 m tidal range. A conservative tracer, lithium, in a lithium bromide (LiBr) solution, was injected into the beach at 1.0 m depth near the mid-tide line. The flow rate was varied between 1.0 and 1.5 L/min, and the resulting injection pressure varied between 3 m and 6 m of water. The concentration of the injected tracer was measured from four surrounding monitoring wells at multiple depths. The HPI associated with a flow rate of 1.5 L/min resulted in a Darcy flux in the cross-shore direction at 1.15 × 10−5 m/s compared to that of 7.5 × 10−6 m/s under normal conditions. The HPI, thus, enhanced the hydraulic conveyance of the beach. The resul... [more]
Computational Fluid Dynamics Simulation of Gas−Solid Hydrodynamics in a Bubbling Fluidized-Bed Reactor: Effects of Air Distributor, Viscous and Drag Models
Ramin Khezri, Wan Azlina Wan Ab Karim Ghani, Salman Masoudi Soltani, Dayang Radiah Awang Biak, Robiah Yunus, Kiman Silas, Muhammad Shahbaz, Shiva Rezaei Motlagh
October 26, 2019 (v1)
Keywords: Computational Fluid Dynamics, fluidized bed, gasification, hydrodynamics, multiphase flow
In this work, we employed a computational fluid dynamics (CFD)-based model with a Eulerian multiphase approach to simulate the fluidization hydrodynamics in biomass gasification processes. Air was used as the gasifying/fluidizing agent and entered the gasifier at the bottom which subsequently fluidized the solid particles inside the reactor column. The momentum exchange related to the gas-phase was simulated by considering various viscous models (i.e., laminar and turbulence models of the re-normalisation group (RNG), k-ε and k-ω). The pressure drop gradient obtained by employing each viscous model was plotted for different superficial velocities and compared with the experimental data for validation. The turbulent model of RNG k-Ɛ was found to best represent the actual process. We also studied the effect of air distributor plates with different pore diameters (2, 3 and 5 mm) on the momentum of the fluidizing fluid. The plate with 3-mm pores showed larger turbulent viscosities above th... [more]
Special Issue: Modeling and Simulation of Energy Systems
Thomas A. Adams
October 26, 2019 (v1)
Keywords: Energy, energy systems, Modelling, operations, Optimization, process design, process systems engineering, Simulation
This editorial provides a brief overview of the Special Issue “Modeling and Simulation of Energy Systems.” This Special Issue contains 21 research articles describing some of the latest advances in energy systems engineering that use modeling and simulation as a key part of the problem-solving methodology. Although the specific computer tools and software chosen for the job are quite variable, the overall objectives are the same—mathematical models of energy systems are used to describe real phenomena and answer important questions that, due to the hugeness or complexity of the systems of interest, cannot be answered experimentally on the lab bench. The topics explored relate to the conceptual process design of new energy systems and energy networks, the design and operation of controllers for improved energy systems performance or safety, and finding optimal operating strategies for complex systems given highly variable and dynamic environments. Application areas include electric powe... [more]
Qualitative Fingerprint Analysis and Multidirectional Assessment of Different Crude Extracts and Essential Oil from Wild Artemisia santonicum L.
Claudio Ferrante, Gokhan Zengin, Luigi Menghini, Alina Diuzheva, József Jekő, Zoltán Cziáky, Lucia Recinella, Annalisa Chiavaroli, Sheila Leone, Luigi Brunetti, Devina Lobine, Ismail Senkardes, Mohamad Fawzi Mahomoodally, Giustino Orlando
October 26, 2019 (v1)
Subject: Biosystems
Keywords: antioxidant, Artemisia, bioactive compounds, enzyme inhibition, essential oil
Artemisia species are used as folk medicines in several countries. This work was aimed to shed more light on the effect of methanol, water, ethyl acetate extracts, and essential oil (EO) of A. santonicum on selected enzymes (cholinesterase, tyrosinase α-amylase, and α-glucosidase) as well of their antioxidant and pharmacological effects. The chemical profile of the essential oil was determined using gas chromatography coupled to mass spectrometry (GC-MS) analysis, while the extracts were chemically characterized by high performance liquid chromatography coupled to mass spectrometry (HPLC-MS). Forty-nine constituents were identified and camphor (36.6%), 1,8-cineole (10.2%), α-thujone (10.1%), borneol (4.5%), and β-thujone (3.6%) were the major components. Overall, 45, 74, and 67 components were identified from the ethyl acetate, methanol, and water extracts, respectively. The EO and extracts showed significant antioxidant properties, in a cell-free model; particularly, methanol and wate... [more]
Understanding the Lack of Reactivity of 2,4-Dihydroxybenzaldehyde Towards the Biginelli Adduct Using Density Functional Theory Molecular Modeling
Virginia Flores-Morales, Eduardo D. Ayala-Medrano, José García-Elías, Margarita L. Martínez-Fierro, Edgar Marquez, José Mora
October 26, 2019 (v1)
Keywords: density functional theory, dihydropyrimidinthione derivatives, intermediaries, mechanism reaction, one-pot reaction
The Biginelli reaction is a multicomponent reaction for obtaining dihydropyrimidinthiones quickly, with multiple substitution patterns. The reaction mechanism remains unclear. Three possible pathways proposed for the reaction are the iminium route, an enamine intermediate, and the Knoevenagel pathway. However, when thiourea was used, no theoretical calculations were reported. Thus, based on the literature, the iminium pathway was used to obtain evidence explaining the lack of reactivity of 2,4-dihydroxybenzaldehyde towards the Biginelli adduct, compared with 4-hydroxybenzaldehyde. This computational study, carried out using the B3LYP/6-31++G(d,p) level of theory, showed an increment of 150 kJ/mol in the activation energy of the slowest pathway, due to the presence of a hydroxyl group in position 2 (ortho) of the aromatic aldehyde, decreasing its reactivity. Natural bond orbital (NBO) calculations suggest that the determinant steps are simultaneous, i.e., the polarization of the carbony... [more]
Evaluation of Oleic Acid and Polyethylene Glycol Monomethyl Ether Conjugate (PEGylated Oleic Acid) as a Solubility Enhancer of Furosemide
Rahul S. Kalhapure, Pradeep Kumar Bolla, Sai HS. Boddu, Jwala Renukuntla
October 26, 2019 (v1)
Subject: Biosystems
Keywords: BCS class IV, furosemide, mPEG, OA-mPEG5000, oleic acid, PEGylated oleic acid, polymersomes, solubility
Poor aqueous solubility limits the therapeutic efficacy of many marketed and investigational drugs. Synthesis of new drugs with improved solubility is challenging due to time constraint and expenses involved. Therefore, finding the solubility enhancers for existing drugs is an attractive and profitable strategy. In this study, PEGylated oleic acid (OA-mPEG5000), a conjugate of oleic acid and mPEG5000 was synthesized and evaluated as a solubilizer for furosemide. OA-mPEG5000 was evaluated as a nanocarrier for furosemide by formulating polymersomes. Solubility of furosemide in milli-Q water and aqueous OA-mPEG5000 solution was determined using shake flask method. At 37 °C, the solubility of furosemide in OA-mPEG5000 (1% w/w) and milli-Q water was 3404.7 ± 254.6 µg/mL and 1020.2 ± 40.9 µg/mL, respectively. Results showed there was a 3.34-fold increase in solubility of furosemide in OA-mPEG5000 compared to water at 37 °C. At 25 °C, there was a 3.31-fold increase in solubilization of furose... [more]
Principal Component Analysis of Blast Furnace Drainage Patterns
Mauricio Roche, Mikko Helle, Henrik Saxén
October 26, 2019 (v1)
Keywords: analysis tool, drainage, hearth, pattern, PCA, tapholes
Monitoring and control of the blast furnace hearth is critical to achieve the required production levels and adequate process operation, as well as to extend the campaign length. Because of the complexity of the draining, the outflows of iron and slag may progress in different ways during tapping in large blast furnaces. To categorize the hearth draining behavior, principal component analysis (PCA) was applied to two extensive sets of process data from an operating blast furnace with three tapholes in order to develop an interpretation of the outflow patterns. Representing the complex outflow patterns in low dimensions made it possible to study and illustrate the time evolution of the drainage, as well as to detect similarities and differences in the performance of the tapholes. The model was used to explain the observations of other variables and factors that are known to be affected by, or affect, the state of the hearth, such as stoppages, liquid levels, and tap duration.
Thermo-Ultrasound-Based Sterilization Approach for the Quality Improvement of Wheat Plantlets Juice
Zahoor Ahmed, Muhammad Faisal Manzoor, Nabila Begum, Abbas Khan, Imranullah Shah, Umar Farooq, Rabia Siddique, Xin-An Zeng, Abdul Rahaman, Azhari Siddeeg
October 26, 2019 (v1)
Subject: Biosystems
Keywords: bioactive compounds, microbial loads, nutritional, thermo–ultrasound, wheat plantlets juice
The impact of thermo−ultrasound (TU) on the quality of fresh wheat plantlets juice is described in this study. Fresh wheat plantlets juice was treated with TU using ultrasound (US) bath cleaner with different treatment variables, including power (70%, 420 W), frequency (40 kHz), processing time (20 and 40 min) and temperature (30, 45 and 60 °C) for the determination of free amino acids, minerals, microbial loads and bioactive compounds. The treatments have non-significant effects in ºBrix, pH, and titratable acidity while a significant increase in non-enzymatic browning, viscosity, and cloud value. The TU treatment at 30 °C for 20 and 40 min has achieved the highest value of total phenolics, flavonoids, total antioxidant capacity, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), carotenoids, anthocyanin contents, chlorophyll (a + b), minerals and free amino acids than other treatments as well as untreated sample. A lightly visible variation in the color was observed among all treatments. TU trea... [more]
Imbalance-Based Irregularity Molecular Descriptors of Nanostar Dendrimers
Zafar Hussain, Mobeen Munir, Shazia Rafique, Tayyab Hussnain, Haseeb Ahmad, Young Chel Kwun, Shin Min Kang
October 26, 2019 (v1)
Subject: Materials
Keywords: complexity of structure, irregularity measure, nanostar dendrimer, NS1[p], NS2[p], NS3[p]
Dendrimers are branched organic macromolecules with successive layers of branch units surrounding a central core. The molecular topology and the irregularity of their structure plays a central role in determining structural properties like enthalpy and entropy. Irregularity indices which are based on the imbalance of edges are determined for the molecular graphs associated with some general classes of dendrimers. We also provide graphical analysis of these indices for the above said classes of dendrimers.
An Investigation on the Effect of the Total Efficiency of Water and Air Used Together as a Working Fluid in the Photovoltaic Thermal Systems
Mustafa Atmaca, İmdat Zafer Pektemir
October 26, 2019 (v1)
Keywords: natural ambient conditions, solar energy, total efficiency, water based PV/T system, water- and air-based PV/T system
The temperature of a PV (photovoltaic) panel increases when it produces electricity but its electrical efficiency decreases when the temperature increases. In addition, the electrical efficiency of the PV panel is very limited. To increase the PV efficiency, the rest of the solar irradiance must be used, together with the temperature being kept at an optimum value. With this purpose, an experimental study was conducted. Firstly, two specific photovoltaic-thermal (PV/T) systems were designed. The first was the PV/T system which used only a water heat exchanger. The other one was the PV/T system that used a water and air heat exchanger. In the latter PV/T system, air passed through both the top of the PV panel and the bottom of it while water passed through only the bottom of the panel in a separate heat exchanger. In this way, the water and air absorbed the thermal energy of the panel by means of separate heat exchangers, simultaneously. In addition to the two systems mentioned above, a... [more]
Computational Fluid Dynamic Simulation of Inhaled Radon Dilution by Auxiliary Ventilation in a Stone-Coal Mine Laneway and Dosage Assessment of Miners
Bin Zhou, Ping Chang, Guang Xu
October 26, 2019 (v1)
Keywords: coal mining, Computational Fluid Dynamics, occupational exposure assessment, radon concentration, ventilation
Inhaled radon status in the laneways of some Chinese stone-coal mines is a cause of concern. In this study, computational fluid dynamics simulations were employed to investigate three flowrates of the dilution gas (2.5, 5, and 7.5 m3/s) and radon distributions at realistic breathing levels (1.6, 1.75, and 1.9 m). The results showed that there are obvious jet-flow, backflow, and vortex zones near the heading face, and a circulation flow at the rear of the laneway. A high radon concentration area was found to be caused by the mining machinery. As the ventilation rate increased, the radon concentrations dropped significantly. An airflow of 7.5 m3/s showed the best dilution performance: The maximum radon concentration decreased to 541.62 Bq/m3, which is within the safe range recommended by the International Commission on Radiological Protection. Annual effective doses for the three air flowrates were 8.61, 5.50, and 4.12 mSv.
Near-Wall Flow Characteristics of a Centrifugal Impeller with Low Specific Speed
Weidong Cao, Zhixiang Jia, Qiqi Zhang
October 26, 2019 (v1)
Keywords: centrifugal pump, flow characteristics, impeller, low specific speed, near-wall region
In order to study the near-wall region flow characteristics in a low-specific-speed centrifugal impeller, based on ANSYS-CFX 15.0 software, Reynolds averaged Navier-Stokes (RANS) methods and renormalization group (RNG) k-ɛ turbulence model were used to simulate the whole flow field of a low specific speed centrifugal pump with five blades under different flow rates. Simulation results of external characteristics of the pump were in good agreement with experimental results. Profiles were set on the pressure side and suction side of impeller blades at the distances of 0.5 mm and 2 mm, respectively, to study the distributions of flow characteristics near the wall region of five groups of blades. The results show that the near-wall region flow characteristics of five groups of blades were similar, but the static pressure, relative velocity, cross flow velocity, and turbulent kinetic energy of profiles on the pressure side were quite different to those on the suction sides, and these charac... [more]
Glycoalkaloids: Structure, Properties, and Interactions with Model Membrane Systems
Bishal Nepal, Keith J. Stine
October 26, 2019 (v1)
Subject: Materials
Keywords: glycoalkaloid, liposome, membrane, monolayer
The glycoalkaloids which are secondary metabolites from plants have proven to be of significant interest for their biological properties both in terms of their roles in plant biology and the effects they exhibit when ingested by humans. The main feature of the action of glycoalkaloids is their strong binding to 3β-hydroxysterols, such as cholesterol, to form complexes with the consequence that membrane structure is significantly perturbed, and leakage or release of contents inside cells or liposomes becomes possible. The glycoalkaloids have been studied for their ability to inhibit the growth of cancer cells and in other roles such as vaccine adjuvants and as synergistic agents when combined with other therapeutics. The glycoalkaloids have rich and complex physical behavior when interacting with model membranes for which many aspects are yet to be understood. This review introduces the general properties of glycoalkaloids and aspects of their behavior, and then summarizes their effects... [more]
Determination of the Potential Impact of Domestic Anaerobic Digester Systems: A Community Based Research Initiative in Rural Bangladesh
Khondokar M. Rahman, Lynsey Melville, David J. Edwards, David Fulford, Wellington Didibhuku Thwala
October 26, 2019 (v1)
Subject: Energy Policy
Keywords: anaerobic digestion, Bangladesh, biogas, Energy, feedstock, impact
This research examines the potential impact of domestic anaerobic digester (AD) systems adopted in Bangladesh and similar developing countries. Cattle dung and poultry litter feed stocks were specifically investigated, because these were freely available and plentiful to people living within agricultural areas of rural Bangladesh. Data was collected to ascertain whether these two representative AD facility types provide tangible social, economic and environmental impact that benefits homeowners. Primary quantitative and qualitative data was obtained by field data collection, and meeting with expert groups and stakeholders. Empirical analysis conducted revealed that variations were found in the biomass feedstocks available on different sites but also differences were apparent in terms of the operations and maintenance (O and M) systems of the biogas plants operated. The biogas and methane yield variation was also measured, and variations were found in the cattle dung and poultry litter... [more]
Special Issue on “Process Modelling and Simulation”
César de Prada, Constantinos C. Pantelides, José Luis Pitarch
October 26, 2019 (v1)
Collecting and highlighting novel developments that address existing as well as forthcoming challenges in the field of process modelling and simulation was the motivation for proposing this special issue on “Process Modelling and Simulation” in the journal Processes [...]
Green Synthesis of Potent Antimicrobial Silver Nanoparticles Using Different Plant Extracts and Their Mixtures
May Reda, Akram Ashames, Zehra Edis, Samir Bloukh, Richie Bhandare, Hamed Abu Sara
October 26, 2019 (v1)
Subject: Materials
Keywords: AgNPs, antibacterial, antifungal, chemical methods, green synthesis, plant extract
Nano-sized metals have been introduced as a promising solution for microbial resistance to antimicrobial agents. Silver nanoparticles (AgNPs) have been proven to possess good antimicrobial activity. Green synthesis of AgNPs has been reported as safe, low cost and ecofriendly. This methodology uses extracts originating from different plants to reduce silver ions from AgNO3 into nano-sized particles. In this study, extracts of several plants including ginger, garlic, capsicum and their mixtures were successfully used to produce AgNPs. Numerous spectroscopic, light scattering and microscopic techniques were employed to characterize the synthesized AgNPs. Agar well diffusion assay was performed to investigate the antimicrobial activity of AgNPs. The biosynthesized AgNPs have spherical shape with a size range of 20−70 nm. Garlic extract, pure or in mixture with ginger extract, generated AgNPs of the smallest size. The presence of the plant-origin capping agents surrounding AgNPs was proven... [more]
Robust Process Design in Pharmaceutical Manufacturing under Batch-to-Batch Variation
Xiangzhong Xie, René Schenkendorf
October 26, 2019 (v1)
Keywords: batch-to-batch variation, freeze-drying, parametric probability-box, pharmaceutical manufacturing, point estimate method, robust process design
Model-based concepts have been proven to be beneficial in pharmaceutical manufacturing, thus contributing to low costs and high quality standards. However, model parameters are derived from imperfect, noisy measurement data, which result in uncertain parameter estimates and sub-optimal process design concepts. In the last two decades, various methods have been proposed for dealing with parameter uncertainties in model-based process design. Most concepts for robustification, however, ignore the batch-to-batch variations that are common in pharmaceutical manufacturing processes. In this work, a probability-box robust process design concept is proposed. Batch-to-batch variations were considered to be imprecise parameter uncertainties, and modeled as probability-boxes accordingly. The point estimate method was combined with the back-off approach for efficient uncertainty propagation and robust process design. The novel robustification concept was applied to a freeze-drying process. Optimal... [more]
Formation and Evolution Mechanism for Carbonaceous Deposits on the Surface of a Coking Chamber
Hao Wang, Baosheng Jin, Xiaojia Wang, Gang Tang
October 26, 2019 (v1)
Keywords: carbonaceous deposits, coke oven, mechanism, spectral analysis
This work aimed to investigate the carbonaceous deposits on the surface of the coking chamber. Scanning electron microscopy (SEM), X-ray fluorescence spectrum (XRF), Fourier transform infrared spectrometer (FTIR), Raman spectroscopy, X-ray diffraction spectrum (XRD), and X-ray photoelectron spectroscopy (XPS) were applied to investigate the carbonaceous deposits. FTIR revealed the existence of carboxyl, hydroxyl, and carbonyl groups in the carbonaceous deposits. SEM showed that different carbonaceous deposit layers presented significant differences in morphology. XRF and XPS revealed that the carbonaceous deposits mainly contained C, O, and N elements, with smaller amounts of Al, Si, and Ca elements. It was found that in the formation of carbonaceous deposits, the C content gradually increased while the O and N elements gradually decreased. It was also found that the absorbed O2 and H2O took part in the oxidation process of the carbon skeleton to form the =O and −O− structure. The oxid... [more]
Adjustable Robust Optimization for Planning Logistics Operations in Downstream Oil Networks
Camilo Lima, Susana Relvas, Ana Barbosa-Póvoa, Juan M. Morales
October 26, 2019 (v1)
Keywords: distribution, oil supply chain, Planning, robust optimization, uncertainty
The oil industry operates in a very uncertain marketplace, where uncertain conditions can engender oil production fluctuations, order cancellation, transportation delays, etc. Uncertainty may arise from several sources and inexorably affect its management by interfering in the associated decision-making, increasing costs and decreasing margins. In this context, companies often must make fast and precise decisions based on inaccurate information about their operations. The development of mathematical programming techniques in order to manage oil networks under uncertainty is thus a very relevant and timely issue. This paper proposes an adjustable robust optimization approach for the optimization of the refined products distribution in a downstream oil network under uncertainty in market demands. Alternative optimization techniques are studied and employed to tackle this planning problem under uncertainty, which is also cast as a non-adjustable robust optimization problem and a stochasti... [more]
The Influence of Nitrogen Absorption on Microstructure, Properties and Cytotoxicity Assessment of 316L Stainless Steel Alloy Reinforced with Boron and Niobium
Sadaqat Ali, Ahmad Majdi Abdul Rani, Riaz Ahmad Mufti, Farooq I. Azam, Sri Hastuty, Zeeshan Baig, Murid Hussain, Nasir Shehzad
October 26, 2019 (v1)
Subject: Materials
Keywords: cytotoxicity, implant, leaching, nickel, nitrogen, stainless steel
In the past, 316L stainless steel (SS) has been the material of choice for implant manufacturing. However, the leaching of nickel ions from the SS matrix limits its usefulness as an implant material. In this study, an efficient approach for controlling the leaching of ions and improving its properties is presented. The composition of SS was modified with the addition of boron and niobium, which was followed by sintering in nitrogen atmosphere for 8 h. The X-ray diffraction (XRD) results showed the formation of strong nitrides, indicating the diffusion of nitrogen into the SS matrix. The X-ray photoelectron spectroscopy (XPS) analysis revealed that a nitride layer was deposited on the sample surface, thereby helping to control the leaching of metal ions. The corrosion resistance of the alloy systems in artificial saliva solution indicated minimal weight loss, indicating improved corrosion resistance. The cytotoxicity assessment of the alloy system showed that the developed modified stai... [more]
Multi-Attribute Decision-Making: Applying a Modified Brown−Gibson Model and RETScreen Software to the Optimal Location Process of Utility-Scale Photovoltaic Plants
Nasser Yimen, Mustafa Dagbasi
October 26, 2019 (v1)
Keywords: analytic hierarchy process (AHP), Brown–Gibson model, Cameroon, multi-criteria decision-making (MCDM), optimal location, photovoltaic, Renewable and Sustainable Energy, RETScreen
Due to environmental and economic drawbacks of fossil fuels, global renewable energy (RE) capacity has increased significantly over the last decade. Solar photovoltaic (PV) is one of the fastest-growing RE technologies. Selecting an appropriate site is one of the most critical steps in utility-scale solar PV planning. This paper aims at proposing a rational multi-criteria decision-making (MCDM) approach based on the Brown−Gibson model for optimal site selection for utility-scale solar PV projects. The proposed model considers the project’s net present value (NPV) along with seven suitability factors and six critical (constraint) factors. The RETScreen software was applied in calculating the NPV, the simple payback period and the carbon emission savings of the project at each alternative site. The weights of the suitability factors were determined using the analytical hierarchy process. Applied to the case study of finding the best location for a 5 MW solar PV project in northern Camero... [more]
A Review of the Chemistry of Anaerobic Digestion: Methods of Accelerating and Optimizing Process Efficiency
Anthony Anukam, Ali Mohammadi, Muhammad Naqvi, Karin Granström
October 26, 2019 (v1)
Keywords: anaerobic digestion, feedstock, methane yield, process chemistry, syntrophic interaction
The anaerobic digestion technology has been in existence for centuries and its underlying theory established for decades. It is considered a useful technology for the generation of renewable energy, and provides means to alleviate problems associated with low access to energy. However, a great deal of current research is targeted towards the optimization of this technology under diverse digestion process conditions. This review presents an in-depth analysis of the chemistry of anaerobic digestion and discusses how process chemistry can be used to optimize system performance through identification of methods that can accelerate syntrophic interactions of different microorganisms for improved methanogenic reactions. Recent advances in addition to old research are discussed in order to offer a general but comprehensive synopsis of accumulated knowledge in the theory of anaerobic digestion, as well as an overview of previous research and future directions and opportunities of the AD techno... [more]
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