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Articles 31 - 44 of 44

Full-Text Articles in Engineering

Development Of Seebeck-Coefficient Measurement Systems Using Kelvin-Probe Force Microscopy, Kazutoshi Miwa, Faiz Salleh, Hiroya Ikeda Apr 2013

Development Of Seebeck-Coefficient Measurement Systems Using Kelvin-Probe Force Microscopy, Kazutoshi Miwa, Faiz Salleh, Hiroya Ikeda

Makara Journal of Technology

Thermoelectric device is investigated by a number of researchers in order to enhance the thermoelectric efficiency. It is known that the efficiency can be improved by quantum effect. However, it is difficult to measure the thermoelectric characteristics of nanometer-scale structures. Thus a new measurement method is expected to be developed. We propose to apply Kelvin-probe force microscopy (KFM) to characterization of thermoelectric materials. KFM can locally observe surface potential of Fermi energy of a sample without touching the sample surface. In the present paper, we estimate the Seebeck coefficient of thin Si-on-insulator layers using KFM.


Recognition System Of Indonesia Sign Language Based On Sensor And Artificial Neural Network, Endang Supriyati, Mohammad Iqbal Apr 2013

Recognition System Of Indonesia Sign Language Based On Sensor And Artificial Neural Network, Endang Supriyati, Mohammad Iqbal

Makara Journal of Technology

Sign language as a kind of gestures is one of the most natural ways of communication for most people in deaf community. The aim of the sign language recognition is to provide a translation for sign gestures into meaningful text or speech so that communication between deaf and hearing society can easily be made. In this research, the Indonesian sign language recognition system based on flex sensors and an accelerometer is developed. This recognition system uses a sensory glove to capture data. The sensor data that are processed into feature vector are the 5-fingers bending and the palm acceleration when …


Performance Optimization Of Microbial Fuel Cell (Mfc) Using Lactobacillus Bulgaricus, Rita Arbianti, Tania Surya Utami, Heri Hermansyah, Deni Novitasari, Ester Kristin, Ira Trisnawati Apr 2013

Performance Optimization Of Microbial Fuel Cell (Mfc) Using Lactobacillus Bulgaricus, Rita Arbianti, Tania Surya Utami, Heri Hermansyah, Deni Novitasari, Ester Kristin, Ira Trisnawati

Makara Journal of Technology

Electrical energy needs in Indonesia are expected to continue to rise. The use of petroleum as a source of energy still dominates, although oil reserves in Indonesia are increasingly being depleted. Therefore, there is a need to develop alternative sources of sustainable energy, such as microbial fuel cell (MFC). In this study, Lactobacillus bulgaricus was used as an electricity producer in a dual-chamber MFC reactor. We investigated the maximum electrical energy by varying the bacterial optical density (OD), the operational time of MFC, the reactor volume, the electrolyte solution, and the configuration of MFC reactor. In this study, the maximum …


Biological Pretreatment Of Oil Palm Frond Fiber Using White-Rot Fungi For Enzymatic Saccharification, Euis Hermiati, Sita Heris Anita, Lucky Risanto, Dyah Styarini, Yanni Sudiyani, Achmad Hanafi, Haznan Abimanyu Apr 2013

Biological Pretreatment Of Oil Palm Frond Fiber Using White-Rot Fungi For Enzymatic Saccharification, Euis Hermiati, Sita Heris Anita, Lucky Risanto, Dyah Styarini, Yanni Sudiyani, Achmad Hanafi, Haznan Abimanyu

Makara Journal of Technology

Oil palm frond is one type of lignocellulosic biomass abundantly and daily available in Indonesia. It contains cellulose which can be converted to glucose, and further processed to produce different kinds of value –added products. The aim of this research is to study the effects of biological pretreatment of oil palm frond (OPF) fiber using Phanerochaete chrysosporium and Trametes versicolor on the enzymatic saccharification of the biomass. The OPF fiber (40-60 mesh sizes) was inoculated with cultures of the two fungi and incubated at 27 °C for 4 weeks. The samples were taken after 1, 2, 3, and 4 weeks …


Agricultural Drought Pattern In West Java Using Thermal Vegetation Index From Modis-Terra Satellite, Dini Daruati, Rahmatulloh Rahmatulloh, Sri Hardiyanti Purwadhi Apr 2013

Agricultural Drought Pattern In West Java Using Thermal Vegetation Index From Modis-Terra Satellite, Dini Daruati, Rahmatulloh Rahmatulloh, Sri Hardiyanti Purwadhi

Makara Journal of Technology

This study examines agricultural drought paddy fields in West Java. The aims of this research are to know the pattern and distribution of paddy field drought in West Java and the correlation between drought and the physical characteristics. The agricultural drought is obtained from TVI (Thermal Vegetation Index) model. TVI is derived from MODIS Terra satellite image, which is the ratio between the LST (Land Surface Temperature) and EVI (Enhanced Vegetation Index). Physical factors studied are rainfall, l slope, geomorphology, soil drainage, and irrigation areas. The most severe drought occurred in September 2006 because of El Nino, covering 806,564 ha, …


Growth Of Crsi2 Nanostructures Using Crcl2 Powder On Si Substrates, Wen Li, Meng Erchao, Tomoji Matsushita, Shingo Oda, Daisuke Ishikawa, Kaito Nakane, Hirokazu Tatsuoka Apr 2013

Growth Of Crsi2 Nanostructures Using Crcl2 Powder On Si Substrates, Wen Li, Meng Erchao, Tomoji Matsushita, Shingo Oda, Daisuke Ishikawa, Kaito Nakane, Hirokazu Tatsuoka

Makara Journal of Technology

Chromium disilicide (CrSi2) nanostructures were grown by the exposure of Si (111) substrates to CrCl2 vapor in an argon gas flow at atmospheric pressure without using any metal catalyst. Dependence of the growth condition on the structural property was investigated. Hexagonal-shaped CrSi2 microrods were grown at 750 °C with 0.05 g of CrCl2. As the quantity of CrCl2 increased to 0.1 g, the bundle of CrSi2 nanowires with microrods and web-liked CrSi2 nanostructure with turning angles were grown at 750 °C and 700 °C, respectively. The preliminary discussion on the growth mechanism of CrSi2 micro- and nanostructures was carried out.


Carbonation Service Life Prediction Of Existing Concrete Viaduct/Bridge Using Time-Dependent Reliability Analysis, Ming-Te Liang, Ran Huang, Shen-Ann Fang Feb 2013

Carbonation Service Life Prediction Of Existing Concrete Viaduct/Bridge Using Time-Dependent Reliability Analysis, Ming-Te Liang, Ran Huang, Shen-Ann Fang

Journal of Marine Science and Technology

This paper examines the predicted carbonation life of an existing concrete viaduct/bridge in the atmospheric environment based on probability and reliability indices. The probability is dependent upon the carbonation rate, carbonation remainder, concrete quality, and concrete cover. The carbonation life is defined as the service life of reinforced concrete (RC) or prestressed concrete (PC) structure at the beginning of time of steel corrosion when concrete cover surfers from carbonation and loses the protection function to steel. The carbonation life is equivalent to the initiation time of corrosion of reinforcement. Both the Chorng-ching viaduct and Wannfwu bridge were offered as illustrative …


Criteria For The Initiation Of Modes Of Response Of A Caisson Subjected To A Breaking Wave Force, Jaw Guei Lin, Chi Chao David Tung Feb 2013

Criteria For The Initiation Of Modes Of Response Of A Caisson Subjected To A Breaking Wave Force, Jaw Guei Lin, Chi Chao David Tung

Journal of Marine Science and Technology

This paper concerns problems of a caisson subjected to a breaking wave force: (1) what are the possible modes of response and (2) the conditions initiate into these modes. These two questions have not been studied. The objective of this paper is to answer these two questions. However, the actual response of a caisson that takes place in each mode is not addressed in this study. A caisson placed on a horizontal frictional base, subjected to a concentrated horizontal force of short duration, applied to the seaward side face of the caisson and accompanied by a corresponding uplift force on …


Analysis Of Corn Stover Structural Properties For Mechanical Processing Applications, Taylor Suess Jan 2013

Analysis Of Corn Stover Structural Properties For Mechanical Processing Applications, Taylor Suess

The Journal of Undergraduate Research

The research objective of this study is to examine the behavior of chopped corn stover biomass as it undergoes a variety of mechanical loading conditions. Biomass materials, including corn stover, have unique properties that make it challenging to effectively and efficiently feed into thermochemical conversion systems that produce biofuels and bioproducts. These properties include large particle size, fibrous structure, and low density, to name a few. The most common difficulty in creating a system like this for corn stover is plugging within mechanical and pneumatic feeding systems. It is hypothesized that the material properties of fibrous corn stover contribute to …


A Simplified Model Of The Internal Combustion Engine, Christofer Neff Jan 2013

A Simplified Model Of The Internal Combustion Engine, Christofer Neff

Undergraduate Journal of Mathematical Modeling: One + Two

This project further investigates a model of a simplified internal combustion engine considered by Kranc in 1977. Using Euler’s method for ordinary differential equations, we modeled the interaction between the engine’s flywheel and thermodynamic power cycle. Approximating with sufficiently small time intervals (0.001 seconds over a period of 12 seconds) reproduced Kranc’s results with the engine having an average angular velocity of 72/sec.


Trajectory Generation For Stair Ascent Walking Using Rayleigh Oscillator, T. Afzal, Andrew B. Wright, Kamran Iqbal Jan 2013

Trajectory Generation For Stair Ascent Walking Using Rayleigh Oscillator, T. Afzal, Andrew B. Wright, Kamran Iqbal

Journal of the Arkansas Academy of Science

This paper describes a trajectory generation technique for stair-ascent walking. The knee, hip and ankle joint trajectory during stair ascent are generated using mutually coupled, nonlinear oscillators. The parameters of the oscillators are tuned using the harmonic balance method, which converts the nonlinear differential equations to a set of algebraic equations. Fourier analysis of data generated by stair-ascent walking is performed to extract the amplitude and the phase of the dominant frequency components for each joint trajectory. The solution for the oscillator is assumed to be a sinusoidal wave and then by harmonic balance method the parameters of the oscillator …


Valence-Length Correlations For Chemical Bonds From Atomic Orbital Exponents, F. D. Hardcastle Jan 2013

Valence-Length Correlations For Chemical Bonds From Atomic Orbital Exponents, F. D. Hardcastle

Journal of the Arkansas Academy of Science

Pauling’s empirical bond valence-length correlation has proven valuable because it offers a quick and convenient way of checking and evaluating molecular structures and determining oxidation states from measured bond lengths. In this study, a simplified quantum-mechanical approach was used to derive Pauling’s empirical bond valence-length relationship by considering overlap of hydrogen-like orbitals. An expression for the b “empirical” fitting parameter was derived in terms of atomic-orbital exponents. A new set of orbital exponents is presented using published atomic/covalent radii and a continuous function for the effective principal quantum. The b parameters calculated from the orbital exponents are consistent with bond …


Design, Fatigue, And Strength Analysis Of A Tie Rod Hydraulic Cylinder Bolt, Jacob Roemen, Donald Webber Jan 2013

Design, Fatigue, And Strength Analysis Of A Tie Rod Hydraulic Cylinder Bolt, Jacob Roemen, Donald Webber

The Journal of Undergraduate Research

This report illustrates strength and fatigue analysis completed on a tie rod hydraulic cylinder bolt from a Lion TX 2500 tie rod hydraulic cylinder. The goal was to: solve for total clamping force, damping force per bolt at 90% proof load strength, amount of force per bolt, find the required number of bolts to hold the hydraulic cylinder together, solve for bolt spacing requirements, estimate a safety factor based on proof load strength, nut shear strength, required nut thickness, the least number of threads that must be engaged, estimate R.R. Moore Bending Fatigue Strengths, estimate the maximum value of P …


Enhanced Tribological Properties Of Surfaces Patterned With Su8/Dlc Microstructures, Luke Osborn Jan 2013

Enhanced Tribological Properties Of Surfaces Patterned With Su8/Dlc Microstructures, Luke Osborn

Inquiry: The University of Arkansas Undergraduate Research Journal

In tribology (the study of friction, wear, and lubrication), it is known that micro-textured surfaces can reduce friction due to decreased contact area between two surfaces. The problem with many micro-textures, however, is their inability to withstand significant amounts of wear, thus limiting their potential uses and overall effectiveness. In this study, connected and isolated microstructures of SU8, a negative tone photoresist, coated with and without diamond-like carbon (DLC), were designed to investigate the effects of these microstructures and DLC coating on the tribological performance of a surface. Friction and wear studies were conducted using a tribometer; surface topography and …