Chemical Engineering Commons^™

Performance Of Air Breathing Direct Methanol Fuel Cell Under Ambient Condition, Jian-Guo Liu, Jun Gu, Tao Yu, Zhi-Gang Zou, T.S Zhao

Journal of Electrochemistry

The performance of the passive DMFC was systematically investigated under an ambient condition by simulating a wide range of temperature and humidity in a high-quality environmentally controlled room.The results indicated that the performance of the passive DMFC was nearly independent of ambient humidity from 30% to 90% RH and water produced in the cathode was expelled mostly from the cell in a liquid state.Compared with the humidity,the ambient temperature has a significant effect on the performance of the passive DMFC.The power density of 30 mW·cm^-2 were obtained at 40℃,while only 10 mW·cm^-2 at 10 ℃.

The Development Of Inverter Fuzzy Logic Control For Induction Motor Control By Vector Control Method In Electric Vehicle, Era Purwanto, Mohammad Ashary, Subagio Subagio, Mauridhi Heri Purnomo

Makara Journal of Technology

The development of Inverter Fuzzy Logic Control for Induction Motor Control by Vector Control Method in Electric Vehicle. In response to concerns about energy cost, energy dependence, and environmental damage, a rekindling of interest in electric vehicles (EV’s) has been obvious. Thus, the development of power electronics technology for EV’s will take an accelerated pace to fulfill the market needs, regarding with the problem in this paper is presented development of fuzzy logic inverter in induction motor control for electric vehicle propulsion. The Fuzzy logic inverter is developed in this system to directed toward developing an improved propulsion system for …

Internet Congestion Control System, Pranoto Hidaya Rusmin, Carmadi Machbub, Agung Harsoyo, Hendrawan Hendrawan

Makara Journal of Technology

Internet Congestion Control System. Internet congestion occurs when resource demands exceeds the network capacity. But, it is not the only reason. Congestion can happen on some users because some others user has higher sending rate. Then some users with lower sending rate will experience congestion. This partial congestion is caused by inexactly feedback. At this moment congestion are solved by the involvement of two controlling mechanisms. These mechanisms are flow/congestion control in the TCP source and Active Queue Management (AQM) in the router. AQM will provide feedback to the source a kind of indication for the occurrence of the congestion …

A Study Of Co2 Absorption Using Jet Bubble Column, Setiadi Setiadi, Nita Tania Hadiyani, Hantizen Hantizen, Dijan Supramono

Makara Journal of Technology

A Study of CO2 Absorption Using Jet Bubble Column. The phenomenon of plunging jet gas-liquid contact occurs quite often in nature, it's momentum carries small air bubbles with it into the reactor medium. The momentum of the liquid stream can be sufficient to carry small bubbles completely to the bottom of the vessel. A stream of liquid falling toward a level surface of that liquid will pull the surrounding air along with it. It will indent the surface of the liquid to form a trumpet-like shape. If the velocity of the stream is high enough, air bubbles will be pulled …

The Role Of 1 And 9 Wt.% Zn In Precipitation Hardening Of Aa319 Aluminium, Bondan Tiara Sofyan, Sari Susanti, Ridwan R. Yusfranto

Makara Journal of Technology

The Role of 1 and 9 wt.% Zn in Precipitation Hardening of AA319 Aluminium. Aluminium alloys are widely used for automotive application due to its low density and high corrosion resistance. For economic reason, casting of automotive products always uses aluminium scrap as charging materials that may result in fluctuation of content of alloying element, such as Zn. This research studies the role of Zn in precipitation hardening of AA319 aluminium alloys. Hardness and tensile testing were conducted to study the mechanical properties of the alloys, while ageing response was followed by hardness measurements. Evolution of microstructures was observed by …

Biomass Production Chlorella Vulgaris Buitenzorg Using Series Of Bubble Column Photo Bioreactor With A Periodic Illumination, Anondho Wijanarko, Dianursanti Dianursanti, Muryanto Muryanto, Josia Simanjuntak, Praswasti Pembangun Dyah Kencana Wulan, Heri Hermansyah, Misri Gozan, Roekmijati Widaningroem Soemantojo

Makara Journal of Technology

Chlorella vulgaris Buitenzorg cultivation using three bubble column photo bioreactors arranged in series with a volume of 200 mL for 130 hours shows an increase of biomass production of Chlorella vulgaris Buitenzorg up to 1.20 times and a decrease of the ability of CO2 fixation compared to single reactor at a periodic sun illumination cycle. The operation conditions on cultivation are as following: T, 29.0oC; P,1 atm.; UG, 2.40 m/h; CO2, 10%; Benneck medium; and illumination source by Phillip Halogen Lamp 20W /12V/ 50Hz. Other research parameters such as microbial carbon dioxide transferred rate (qco2), CO2 transferred rate (CTR), energy …

Ad Hoc On-Demand Distance Vector (Aodv) Routing Protocol Performance Evaluation On Hybrid Ad Hoc Network: Comparison Of Result Of Ns-2 Simulation And Implementation On Testbed Using Pda, Riri Fitri Sari, Abdusy Syarif, Bagio Budiardjo

Makara Journal of Technology

Ad Hoc on-Demand Distance Vector (AODV) Routing Protocol Performance Evaluation on Hybrid Ad Hoc Network: Comparison of Result of Ns-2 Simulation and Implementation on Testbed using PDA. In Mobile Ad hoc NETwork (MANET), node supplemented with wireless equipment has the capacity to manage and organise autonomously, without the presence of network infrastructures. Hybrid ad hoc network, enable several nodes to move freely (mobile) to create instant communication. Independent from infrastructure. They could access the Local Area Network (LAN) or the Internet. Functionalities of ad hoc network very much dependent on the routing protocol that determines the routing around node. Ad …

Substrates Preparation From Woody Tropical Waste Biomass For Biohydrogen Production, Dwi Susilaningsih, Theresia Umi Harwati, Khairul Anam, Yopi Yopi

Makara Journal of Technology

Substrates Preparation from Woody Tropical Waste Biomass for Biohydrogen Production. Addressing to the global warming problem, energy crisis and pollution, hydrogen production by micro-organisms using biotechnological approach should be considered, since it fulfils the recent society requirement to safely produce, renewable and environmental friendly energy. Hydrogen is one of the most promising green energy sources, because it is easily converted to electricity and cleanly combustible. There are three types of micro-organisms for hydrogen production, the first is cyanobacteria through the photosynthesis process, the second is anaerobic bacteria, which use organic substances as electron donor and energy and convert them to …

The Effect Of Ozone And Zeolite Concentration To The Performance Of The Treatment Of Wastewater Containing Heavy Metal Using Flotation Process, Eva Fathul Karamah, Setijo Bismo, Hotdi M. Simbolon

Makara Journal of Technology

The Effect of Ozone and Zeolite Concentration to the Performance of the Treatment of Wastewater Containing Heavy Metal Using Flotation Process. Industrial wastewater which contains heavy metal cannot be disposed to the environment directly, due to its toxicity. In this research, separation of metal from wastewater was conducted by sorptive flotation method, using Lampung natural zeolite as bonding agent. The most common diffuser used in the flotation process is air or oxygen. In this research, ozone is used as diffuser because it is a stronger oxidant and more dissolvable in water than oxygen. Besides, ozone is a coagulant aid and …

Building Fire Safety Audit At Faculty X, University Of Indonesia, Year 2006, Fatma Lestari, Rm. Yodan Amaral Panindrus

Makara Journal of Technology

Building Fire Safety Audit at Faculty X, University of Indonesia, Year 2006. Fire may cause loss of life, material and valuable assets. The objective of this study is to conduct audit for fire safety and emergency response in the building at Faculty X, University of Indonesia, Depok. The audit results on the building fire safety facilities including emergency response and preparedness are then compared to the Building Code Australia (BCA) and Indonesian regulation on the building fire safety (Kep.MenPU.No 10 and 11/KPTS/2000). The building selected are Building A, B, C, D, F and G. Building classification for A, B, D, …

Mechanism Of The Cathode Reduction Of Ti(Ⅳ) In Molten Na3Alf6-Alf3, Hai-Bin Sun, Xiu-Rong Zuo, Zhi-Guo Zhong, Xue-Hui Hu

Journal of Electrochemistry

The mechanism of TiO₂ electrode process has been investigated by cyclic voltammetry and chronopotentiometry on the tungsten filament in molten Na₃AlF₆-AlF₃ salts at 990 ℃.The experimental results showed that electrochemical reduction of Ti(Ⅳ) precede were two steps,firstly Ti(Ⅳ) was reduced to Ti(Ⅱ),then Ti(Ⅱ) was reduced to Ti,namely: Ti(Ⅳ)→Ti(Ⅱ)→Ti.

Effects Of Oxidation Methods On The Stability Of Coooh Conductive Network In Foam Nickel Electrodes, Xiao-Feng Li, Yan-Wei Wei, Hui-Chao Dong

Journal of Electrochemistry

Two kinds of the cobalt oxyhydroxide conductive networks in foam nickel electrodes were prepared by different methods i.e.the electrochemical-oxidation(EO) and chemical-oxidation(CO) and which redox behaviors were studied by using cyclic voltammetry and X-ray diffraction measurements.The results show that the CoOOH(CO) has better redox reversibility than CoOOH(EO) and the structure of the former can be kept when nickel electrodes are subjected to a negative potential.Thus,98.7% capacity retention is demonstrated on nickel/metal-hydride batteries with CoOOH(CO) conductive network after being imposed over-discharge state storage;on the contrary,only 83.3% capacity retention is found on the batteries with CoOOH(EO) conductive network.

Synthesis Of 2,2′-Dichlorohydrazobenzene Using An Ion Exchange Membrane, Chao Zhang, Pei-Jin Li

Journal of Electrochemistry

Using an ion exchange membrane as a separator,the 2,2′-Dichlorohydrazobenzene is synthesized by the electrolytic reduction of o-chloronetrobenzene.The effects of electrode activation condition,current density,electrolyte temperature on electrolytic reduction are discussed.It was found that the optimum reaction temperature is 80 ℃.When the electrolyte concentration was 30% NaOH at the anode and 10% NaOH at the cathode,current density is 4.2A/dm²,the current efficiency reached 73% and yield is 83%.

Effect Of Au At Different States On Electrocatalytic Performance Of Pd Catalyst For Oxidation Of Formic Acid, Xin Wang, Ya-Wen Tang, Tian-Hong Lu

Journal of Electrochemistry

Using liquid-reduction or complex-redution method,four catalysts,i.e,the Au/C,Pd/C,Pd-Au/C-T and Pd-Au/C-H were preparated and which electroanalytic activities and stabilities for the oxidation of formic acid were compares.It was found that the Au/C catalyst has no electrocatalytic activity,and the Pd/C catalyst possesses the good electrocatalytic performance for the oxidation of formic acid.The addition of Au into the Pd/C catalyst can increase the electrocatalytic activity and stability.Especially,the electrocatalytic activity and stability of the Pd-Au/C-T catalyst with the alloy of Pd and Au are better than that of the of the Pd-Au/C-H catalyst,in which,Pd and Au do not form the alloy.The investigation of its reason …

Synthesis Of Adipic Acid From Cyclohexanol By Electrochemical Oxidation Using Cr2O72-/Cr3+ As Indirect Oxidant, Zhen-Hai Liang, Yu-Qing Cui, Hong-Yan Sun

Journal of Electrochemistry

Adipic acid was synthesized by electro-oxidation of cyclohexanol taking Cr₂O₇^2-/Cr³⁺ as indirect oxidant.The best technological conditions were optimized by orthogonal experiment.The optimum condition are as follows: the temperature is 35 ℃,ratio of crude material is n(cyclohexanol)∶n(Cr₂O₇^2-)=0.4∶1 and concentration of H₂SO₄ is 4 mol·L^-1.Under these conditions,the yield of adipic acid can reach 70.29%.Moreover,The effects of concentration of Ag₂SO₄,(NH₄)₂SO₄,H₂SO₄and current density on the formation of Cr₂O₇^2-were also …

The Influence Of The Sputtering Power On The Structural And Electrochemical Properties Of Tin Oxide Films, Min-Zhen Cai, Jie Song, Ming-Sen Zheng, Qi-Hui Wu, Sun-Tao Wu, Quan-Feng Dong

Journal of Electrochemistry

Tin oxide films were deposited on silicon substrates at room temperature using the radio frequency(RF) magnetron sputtering with different sputtering power.The influence of sputtering power upon the crystal structure,surface morphology and electrochemical properties of tin oxide films were then investigated.The XRD and SEM results illustrate that the phase of tin oxide thin films changed from amorphous to crystalline and the grain size augments with the increase of the sputtering power.The constant current charge and discharge cycle tests imply that the initial irreversible capacity loss of Li/tin oxide batteries increase and which capacity decrease as the sputtering power increases.The sputtering power …

Thermal Damage Approach Of Concrete: Application To Specimens Subjected To Combined Compressive And High Temperature Loads, Abdellah Menou, Ghassan Mounajed, Hocine Boussa, Christian La Borderie, Khalid Lafdi

Chemical and Materials Engineering Faculty Publications

Within the framework of study of concrete structures subjected to fire, .a theoretical and experimental work was conducted. The aim of this study was to investigate and to model the damage mechanisms of concrete after their exposure to high temperatures. The multiphase Digital Concrete Model as well as the damage model, MOD EV, which were both implemented on the finiteelem~ rit software package, SYMPHONIE, were used simμltaneously to assess the thermal damage of the concrete. In order to validate the thermal damage model, an experimental investigation was performed. The mechanical characteristics of 5 cementitious materials, which included cement paste, mortar, …

Morphologies And Kinetics Of A Dewetting Ultrathin Solid Film, Mikhail Khenner

Mathematics Faculty Publications

The surface evolution model based on geometric partial differential equation is used to numerically study the kinetics of dewetting and dynamic morphologies for the localized pinhole defect in the surface of the ultrathin solid film with the strongly anisotropic surface energy. Depending on parameters such as the initial depth and width of the pinole, the strength of the attractive substrate potential and the strength of the surface energy anisotropy, the pinhole may either extend to the substrate and thus rupture the film, or evolve to the quasiequilibrium shape while the rest of the film surface undergoes phase separation into a …

Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Mikhail Khenner

Mathematics Faculty Publications

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonlinear amplitude equation for the averaged film thickness. We show that there exists a window in the frequency-amplitude domain where the parametric and shear-flow instabilities of the pulsatile flow do not emerge. As a consequence, in this window the averaged description …

Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonlinear amplitude equation for the averaged film thickness. We show that there exists a window in the frequency-amplitude domain where the parametric and shear-flow instabilities of the pulsatile flow do not emerge. As a consequence, in this window the averaged description …

Enhanced Stability Of A Dewetting Thin Liquid Film In A Single-Frequency Vibration Field, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

Dynamics of a thin dewetting liquid film on a vertically oscillating substrate is considered. We assume moderate vibration frequency and large (compared to the mean film thickness) vibration amplitude. Using the lubrication approximation and the averaging method, we formulate the coupled sets of equations governing the pulsatile and the averaged fluid flows in the film, and then derive the nonlinear amplitude equation for the averaged film thickness. We show that there exists a window in the frequency-amplitude domain where the parametric and shear-flow instabilities of the pulsatile flow do not emerge. As a consequence, in this window the averaged description …

Morphologies And Kinetics Of A Dewetting Ultrathin Solid Film, Mikhail Khenner

Mathematics Faculty Publications

The surface evolution model based on geometric partial differential equation is used to numerically study the kinetics of dewetting and dynamic morphologies for the localized pinhole defect in the surface of the ultrathin solid film with the strongly anisotropic surface energy. Depending on parameters such as the initial depth and width of the pinole, the strength of the attractive substrate potential and the strength of the surface energy anisotropy, the pinhole may either extend to the substrate and thus rupture the film, or evolve to the quasiequilibrium shape while the rest of the film surface undergoes phase separation into a …

High Performance Zno Varistors Prepared From Nanocrystalline Precursors For Miniaturised Electronic Devices, Suresh Pillai, Declan Mccormack, John Kelly, Raghavendra Ramesh

Articles

An industrially viable solution-based processing route using minimal amounts of solvent has been used to prepare bulk quantity nanopowders (average particle size 15.3 nm) for the fabrication of ZnO varistors. The xerogels, calcined powders and sintered materials were fully characterised. The preparation of varistors from nanopowders has been optimised by studying the effect of temperature on grain growth, densification and breakdown voltage. The varistors are prepared by sintering at 1050 C for 2 hours, a temperature that is significantly lower than that used in the current industrial process. Highly dense varistor discs prepared from the sintered material produce devices, with …

Effect Of Carbon Nanofiber-Matrix Adhesion On Polymeric Nanocomposite Properties—Part Ii, Khalid Lafdi, William Fox, Matthew Matzek, Emel Yildiz

Chemical and Materials Engineering Faculty Publications

A successful integration of two independent phases with good adhesion is imperative for effective translation of superior carbon nanofiber filler properties into a physically superior carbon nanocomposite. Carbon nanofibers were subjected to electrochemical oxidation in 0.1 M nitric acid for varying times.

The strength of adhesion between the nanofiber and an epoxy matrix was characterized by flexural strength and modulus. The surface functional groups formed and their concentration of nanofibers showed a dependence on the degree of oxidation. The addition of chemical functional groups on the nanofiber surface allows them to physically and chemically adhere to the continuous resin matrix. …

Enhanced Dielectric Properties In Single Crystal-Like Bifeo3 Thin Films Grown By Flux-Mediated Epitaxy, S.-H. Lim, M. Murakami, J. H. Yang, S.-Y. Young, Jason R. Hattrick-Simpers, M. Wuttig, L. G. Salamanca-Riba, I. Takeuchi

Faculty Publications

We have fabricated single crystal-like BiFeO₃ (BFO) thin films by flux-mediated epitaxy using pulsed laser deposition(PLD). The Bi–Cu–O flux composition and its thickness were optimized using composition spread, thickness gradient, and temperature gradient libraries. The optimized BFO thin films grown with this technique showed larger grain size of ∼2μm and higher dielectric constant in the range of 260–340 than those for standard PLD grown films. In addition, the leakage current density of the films was reduced by two orders of magnitude compared to that of standard PLD grown films.

Carbon Nanoadditives To Enhance Latent Energy Storage Of Phase Change Materials, Shadab Shaikh, Khalid Lafdi, Kevin P. Hallinan

Chemical and Materials Engineering Faculty Publications

Latent energy storage capacity was analyzed for a system consisting of carbon nanoparticlesdopedphase changematerials (PCMs). Three types of samples were prepared by doping shell wax with single wall carbon nanotubes(SWCNTs), multiwall CNTs, and carbon nanofibers. Differential scanning calorimetry was used to measure the latent heat of fusion. The measured values of latent heat for all the samples showed a good enhancement over the latent heat of pure wax. A maximum enhancement of approximately 13% was observed for the wax/SWCNT composite corresponding to 1% loading of SWCNT. The change in latent heat was modeled by using an approximation for the intermolecular …

Nitrogen And Hydrogen Plasma Treatments Of Multiwalled Carbon Nanotubes, John G. Jones, A. R. Waite, Christopher Muratore, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

This article investigates plasma treatment of vertically aligned multiwall carbon nanotube (CNT) films in different plasma environments for modification of surface chemistry and morphology. The surfaces of the CNTs were functionalized with a pulsed dc plasma treatment, where the power was directly applied to the nanotube film in low pressure argon/nitrogen and argon/hydrogen backgrounds. Optical emission spectroscopy was used to detect atomic and molecular excitations in the gas mixtures as well as in pure gases in the vicinity of the CNT films. In situx-ray photoelectron spectroscopy was performed on the treated samples to examine CNT surface chemistry after treatment. …

Using Science, Engineering, And Education To Address Water Supply Challenges In The Highlands Of Guatemala, Andrew Curtis Elmore, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

The Guatemalan Highlands is a Popular Destination for Non-Government Organizations Interested in Performing Relief Projects. U.S.-Based Organizations Such as Rotary International, Engineers Without Borders, and Various Religious Organizations Travel to Guatemala to Conduct Humanitarian Activities Which May Be Effective for the Short Term, But It is Not Clear that the Efforts Have a Systematic Impact. Students and Faculty at the University of Missouri-Rolla Have Systematically Studied Water Supply Issues Including Undergraduate and Graduate Research Projects and Undergraduate Engineering Courses Such as International Capstone Design. Materials Engineers Have Been Involved in the Study of Ceramic-Based Water Treatment Devices. These Microfilters Have …

Electrochemical Oxidization Of Herring Sperm Dna And Its Interaction With Histone, Juan Xu, Gui-Ping Huang, Hong Li, Wei Zhu

Journal of Electrochemistry

The voltammetric behavior of herring sperm DNA at glassy carbon electrode and its interaction with histone have been investigated by using cyclic voltammetry,differential pulse voltammetry,and fluorescence measurement.In the potential range of 0.20 V to 1.25 V,it is found that an irreversible oxidative peak is exhibited in acid solution,but in the neutral or alkaline solution two oxidative peaks are observed.Oxidative peak potential values show a negative shift with increasing pH via a slope of-57 mV·pH-1 and a linear relation with DNA concentration in the range of 0.45 to 8.20 mmol·L^-1.In the presence of histone,the oxidative peak current of DNA …

Eiectro-Oxidation Of Methanol On Pdnio/C Catalyst In Alkaline Medium, Mei-Li Wang, Lin Sang, Cheng-De Huang

Journal of Electrochemistry

The electro-oxidation of methanol in alkaline electrolyte at in-house synthesized PdNiO/C and Pd/C catalysts and the effect of heat treatment on the structure and performance of catalysts were studied by cyclic voltammetry,chronoamperometry,chronopotentiometry and X-ray diffraction methods.It is shown that when the reduction temperature is 70℃ and the ratio between Pd and Ni is 8∶2,The PdNiO/C catalyst presents a highest activity for methanol electrooxidation.Calcining can increase the particle size and crystallinity of catalysts,but decrease the dispersion and activity of catalysts, too.Besides,the NiO is disengaged from Pd lattice by heat-treatment.The optimal PdNiO/C catalyst shows higher catalytic activity and much better poisoning resistance …