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Articles 10081 - 10110 of 16756

Full-Text Articles in Engineering

Finite Element Analysis Of Bolted Connections Under Fire, Ke Liu, Qiaqia Zhu, Amit H. Varma Aug 2014

Finite Element Analysis Of Bolted Connections Under Fire, Ke Liu, Qiaqia Zhu, Amit H. Varma

The Summer Undergraduate Research Fellowship (SURF) Symposium

Over the course of human history, fire disasters are one of the major catastrophes that causes loss of lives and properties. In order to ensure building safety against fire, civil engineers seek to understand the behavior of structures at high temperatures. Moreover, they need to study the behavior of bolted connections, given the important role it plays in steel structures. Sarraj (2007) proposed a plate-bearing computational model used to describe this behavior; however, it has never been experimentally verified. Prior to this specific project, a series of single-bolted connection tests at 400°C and 600°C were conducted in the Bowen Laboratory …

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Development Of A Nanomanufacturing Process To Produce Atomically Thin Black Phosphorus, Andrew Stephens, Zhe Luo, Xianfan Xu Aug 2014

Development Of A Nanomanufacturing Process To Produce Atomically Thin Black Phosphorus, Andrew Stephens, Zhe Luo, Xianfan Xu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Atomically thin black phosphorus (phosphorene) has both unique and desirable properties that differ from bulk black phosphorus. Unlike graphene, phosphorene has a bandgap, which makes it potentially useful for applications in the next generation of transistors. Large-scale applications of phosphorene, like other 2D materials, are limited by current production methods. The most common method of making phosphorene is mechanical exfoliation, which can only produce small and irregular quantities. In this work we investigate a top-down method of producing phosphorene by using a scanning ultrafast laser to thin black phosphorus flakes. Because the bandgap of phosphorene increases as layers are removed, …

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Molecular Exploration Tool, Weiyi Cao, Nicolas Onofrio, Alejandro Strachan Aug 2014

Molecular Exploration Tool, Weiyi Cao, Nicolas Onofrio, Alejandro Strachan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Density Functional Theory (DFT) which is based on quantum mechanics theory has been broadly used to compute the energy and the structure of molecules and solids. However, the DFT method is limited when running calculations for a large system and only thousands of atoms can be solved. Alternatively, Molecular Dynamics (MD) simulation can be used to investigate the properties of the atomic system for large systems in the classical mechanics approximation. When running the MD simulation, the electronic structure is approximated by Force Fields (FF) which can be parametrized against DFT calculations. Nevertheless, the accuracy of the MD results and …

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Bio-Inspired Helicoidal Composites: 3d Printing And Experiments, Michael E. Jones, Pablo Zavattieri, Nobphadon Suksangpanya Aug 2014

Bio-Inspired Helicoidal Composites: 3d Printing And Experiments, Michael E. Jones, Pablo Zavattieri, Nobphadon Suksangpanya

The Summer Undergraduate Research Fellowship (SURF) Symposium

Materials that are impact resistant enough for personal protection in sports, transport, and combat are not also lightweight, strong, tough, and impact tolerant. Nature can provide inspiration for novel materials that can meet these needs. The hierarchical composite of the stomatopod’s, or mantis shrimp’s, dactyl club has been shown to have high impact resistance and damage tolerance due to its helicoidal fiber reinforcement(1,2). Analyzing helicoidal composites of different pitch angles (angles between adjacent rows of fibers) under quasi-static, displacement-controlled loading has provided insights into the fracture mechanisms of the composite structure and how they affect the macroscopic properties of the …

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Development Of Electron Microscopy Analysis And Simulation Tools For Nanohub, Mingxuan Lu, Chang Wan Han, Benjamin P. Haley, Volkan Ortalan Aug 2014

Development Of Electron Microscopy Analysis And Simulation Tools For Nanohub, Mingxuan Lu, Chang Wan Han, Benjamin P. Haley, Volkan Ortalan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Electron microscopy has a crucial role in the field of materials science and structural biology. Although electron microscopy gives lots of important results and findings, some additional simulations and image processing/reconstruction is required to get more information from the data that are collected from the experiments. For this purpose, researchers are using IMOD1 and QSTEM2 for electron microscopy analysis and simulation. IMOD is a set of programs used for tomographic reconstruction and 3D visualization and QSTEM is used for quantitative simulations of TEM and STEM images. However, IMOD and QSTEM are hard to install or use for beginners …

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Micro-Mechanics Simulation Tool Optimization, Ruixuan Ren, Marisol Koslowski Aug 2014

Micro-Mechanics Simulation Tool Optimization, Ruixuan Ren, Marisol Koslowski

The Summer Undergraduate Research Fellowship (SURF) Symposium

Crystalline films grown epitaxially on substrates consisting of a different crystalline material are of considerable interest in optoelectronic devices and the semiconductor industry. One way to progress in this field is to develop simulation tools based on specially designed numerical method. A nanoHUB simulation tool was developed based on the phase field theory, which considers the propagation of dislocations inside the crystalline film. However, the current tool needs several improvements to be more realistic and user-friendly. First, the inputs of the simulation tool are adjusted so that the user can use this tool directly without any additional calculation. The output …

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He+ Ion Irradiation On Tungsten Surface In Extreme Conditions, George I. Joseph, Jitendra Tripathi, Sivanandan S. Harilal, Ahmed Hassanein Aug 2014

He+ Ion Irradiation On Tungsten Surface In Extreme Conditions, George I. Joseph, Jitendra Tripathi, Sivanandan S. Harilal, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Higher melting point (3695K), lower sputtering yield and most importantly, lower in-bulk, and co-deposit retention at elevated temperature makes tungsten (W) as a potential candidate for plasma-facing component (PFC) in the international thermonuclear experimental reactor (ITER)-divertor. Helium ion (He+) bombardment on W can cause wide variety of microstructural evolution, such as dislocation loops, helium holes/bubbles and fibre-form nanostructures (Fuzz) etc. In this work, 100 eV He+ ion irradiation, at temperature ranges from 500°C to 1000°C, will be performed on mechanically polished mirror like W surfaces. The surface modification and compositional analysis, due to ion irradiation, will be …

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Microstructure Development Of Granular System During Compaction, Chen Shang, Marcial Gonzalez Aug 2014

Microstructure Development Of Granular System During Compaction, Chen Shang, Marcial Gonzalez

The Summer Undergraduate Research Fellowship (SURF) Symposium

Granular materials is the second most manipulated material in the industry today. They are easy to transport and more and more newly developed materials cannot stand the process of traditional casting, like energetic materials and bio-materials, but will survive the powder compaction process. Having a better understanding of the microstructure development of granular systems during compaction process, especially for particles that will heavily deform under loading, will give an insight of how to better process the powders to produce materials with overall better performance comparing to bulk materials. The main theory and mechanism applied are Hertz law and nonlocal contact …

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Simulation Of Bio-Inspired Porous Battery Electrodes, Raju Gupta, R. Edwin Garcia, Rui Tu Aug 2014

Simulation Of Bio-Inspired Porous Battery Electrodes, Raju Gupta, R. Edwin Garcia, Rui Tu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Advancement of technology has led to the increase in use of electronic devices. However, longer life of the rechargeable battery used in electronic devices is one of the biggest issue and demand in the world of electronic devices at present. Battery's performance is affected by the orientation, arrangement, shape and size, and porosity of the materials out of which battery electrodes are made. The goal of this project is to develop a set of numerical libraries that allow developing material micro structures that will allow increasing the performance of rechargeable batteries. We focused on the development of an algorithm that …

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Crack Propagation Simulation Tool, Nilofer Rajpurkar, Hojin Kim, Alejandro Strachan Aug 2014

Crack Propagation Simulation Tool, Nilofer Rajpurkar, Hojin Kim, Alejandro Strachan

The Summer Undergraduate Research Fellowship (SURF) Symposium

In the massively engineered world that exists today, understanding material behavior is of paramount importance in caring for human safety in design. Molecular dynamic simulations on crack propagation through materials allow visualization of material behavior under stress. The tool, developed by the nanoHUB group as a part of the Network for Computational Nanotechnology at Purdue University, makes performing such simulations accessible to undergraduate students, highly qualified researchers, and all those in between. First, the input deck for the simulation parameters was simplified from the complex, language-specific code into a simple, user-friendly Graphic User Interface (GUI). Several interesting example cases were …

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Characterization Of Mechanical Properties Displayed In Body Armor Ballistic Fibers, Dawei Li, Matthew Hudspeth, Weinong Wayne Chen Aug 2014

Characterization Of Mechanical Properties Displayed In Body Armor Ballistic Fibers, Dawei Li, Matthew Hudspeth, Weinong Wayne Chen

The Summer Undergraduate Research Fellowship (SURF) Symposium

The current body armor systems manufactured using ballistic fibers are not performing as theoretical results predict and are causing injuries. The actual maximum projectile penetration speed that the body armor can endure is significantly lower than the theoretical maximum speed, thus causing a costly build-test relationship that is not aided with modeling design efforts. The main aim of this research is to determine the maximum penetration speeds for ballistic yarns and fabrics. Secondary aim is to examine the common assumption that during transverse impact, single fiber is under pure tension and shear stress is negligible. To examine aforementioned assumption, fibers …

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Dynamic Response Of Textile Material Under Transverse Impact, Yuchen Zheng, Matthew C. Hudspeth, Weinong W. Chen Aug 2014

Dynamic Response Of Textile Material Under Transverse Impact, Yuchen Zheng, Matthew C. Hudspeth, Weinong W. Chen

The Summer Undergraduate Research Fellowship (SURF) Symposium

Textile materials, such as Dyneema and Kevlar, are the major raw materials for state of the art military or personal security armor vests. However, in impact experiments, actual observed penetration speed is much lower than theoretically predicted penetration speed. Each armor vest is composed of high performance yarns which are woven together to form fabrics, which when stacked together form a vest. Understanding penetration behavior of yarns is essential to evaluate the performance of fabric, which will be useful for the design of better vests. The project is composed of three parts: static experiments, dynamic yarn experiments and dynamic fabric …

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Characterization Of Swelling Ratio And Water Content Of Hydrogels For Cartilage Engineering Applications, Emily E. Gill, Renay S.-C. Su, Julie C. Liu Aug 2014

Characterization Of Swelling Ratio And Water Content Of Hydrogels For Cartilage Engineering Applications, Emily E. Gill, Renay S.-C. Su, Julie C. Liu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Due to the high prevalence of arthritis and cartilage-related injuries, tissue engineers are studying ways to grow cartilage tissue replacements. Resilin, an elastomeric protein found in insect cuticles, is known for its extraordinary resilience and elasticity. In previous studies, recombinant resilin-based hydrogels, or cross-linked protein networks, exhibited potential for use in cartilage tissue scaffolds. Our lab successfully developed resilin-based proteins with a sequence based on the mosquito gene and showed that resilin-based hydrogels possess mechanical properties of the same order of magnitude as native articular cartilage. In addition, these mechanical properties can be controlled by changing the protein concentration. To …

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Simulation Of Bio-Inspired Porous Battery Separators, Yumeng Xie, Edwin Garcia, Aniruddha Jana Aug 2014

Simulation Of Bio-Inspired Porous Battery Separators, Yumeng Xie, Edwin Garcia, Aniruddha Jana

The Summer Undergraduate Research Fellowship (SURF) Symposium

Li-Ion rechargeable battery is one of the most-used rechargeable batteries around the industry of the world. The battery is most used in most electronic devices, electrical cars. But the battery separator is one of the mainly problem that limits the service life. If we can find the way to improve the performance of the battery separator, we can highly increase the service life of the Li-Ion battery. The goal of the project 'Simulation of Bio-Inspired Porous Battery Separators' is to generate a tool for users in order to create computer models of bio-inspired porous structures that resemble porous separators layer …

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Design And Fabrication Of A Novel Electrospinning System For Musculoskeletal Tissue Regeneration, Carter L. Chain, Maggie R. Del Ponte, Meng Deng, Feng Yue, Shihuan Kuang Aug 2014

Design And Fabrication Of A Novel Electrospinning System For Musculoskeletal Tissue Regeneration, Carter L. Chain, Maggie R. Del Ponte, Meng Deng, Feng Yue, Shihuan Kuang

The Summer Undergraduate Research Fellowship (SURF) Symposium

Disease and injury to human tissue, especially musculoskeletal tissue, is a prevalent concern to the public, affecting millions of people each year. Current treatment options involving autografts and allografts are hindered by limited availability and risk of immunogenicity, respectively. In order to overcome these limitations, a transdisiplinary regenerative engineering strategy has emerged with a focus on the development of biomimetic scaffolds that closely mimic the properties of the native tissues. For example, the structure of muscle tissue is characterized by oriented muscle fibers. However, fabrication of aligned nanofiber structures that mimic the anisotropic organization of muscle presents significant engineering challenges. …

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Rheo-Piv Investigation Of Fracture And Self-Healing In A Triblock Copolymer Gel, Benjamin A. Helfrecht, Travis L. Thornell, Kendra A. Erk Aug 2014

Rheo-Piv Investigation Of Fracture And Self-Healing In A Triblock Copolymer Gel, Benjamin A. Helfrecht, Travis L. Thornell, Kendra A. Erk

The Summer Undergraduate Research Fellowship (SURF) Symposium

Physically associating polymer gels have shown the ability to heal after failure, making them promising candidates for various medical applications or consumer products. However, the processes by which these materials self-heal is not well-understood. This study seeks to explain the self-healing behavior of the triblock copolymer poly(methyl methacrylate)-poly(n-butyl acrylate)-poly(methyl methacrylate), or PMMA-PnBA-PMMA, by probing the material’s post-fracture behavior with rheometry and particle image velocimetry (PIV). The self-healing behavior was studied by deforming each gel in shear until failure multiple times with “recovery” periods in-between. PIV was used to verify the occurrence of each fracture in both time and space. Stress …

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Implementing The ‘Frozen Potential’ Approach On Adept To Analyze Thin Film Solar Cells, Abhirit Kanti, Raghu Vamsi Krishna Chavali, Mark S. Lundstrom Phd, Muhammad A. Alam Phd Aug 2014

Implementing The ‘Frozen Potential’ Approach On Adept To Analyze Thin Film Solar Cells, Abhirit Kanti, Raghu Vamsi Krishna Chavali, Mark S. Lundstrom Phd, Muhammad A. Alam Phd

The Summer Undergraduate Research Fellowship (SURF) Symposium

Thin film solar cells have higher absorption coefficients than traditional Silicon solar cells. This means that lesser material is required to produce the same power output for a given intensity of solar illumination. As a result, they are less expensive, easier to install and have a wider range of applications. Analyzing the performance of cells requires separating the current into the photocurrent and the injection current based on the ‘Superposition Principle’. For thin film solar cells, this cannot be done using the conventional method. This is because these components are interdependent, and so modeling one’s behavior requires understanding the other. …

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Investigation Of Fracture And Healing Behavior Of Thermoreversible Gels Via Oscillation Rheology, Krithika Subramaniam, Travis Thornell, Kendra Erk Aug 2014

Investigation Of Fracture And Healing Behavior Of Thermoreversible Gels Via Oscillation Rheology, Krithika Subramaniam, Travis Thornell, Kendra Erk

The Summer Undergraduate Research Fellowship (SURF) Symposium

Thermoreversible gels have the unique ability to self-heal, or repair themselves, once they are fractured. They are physically cross-linked, thus providing them with the capability to reform their broken bonds as a function of temperature. The objective of this project is to determine the extent of the gels’ recovery. If self-healing does in fact occur, these gels can be applied in various industries, including medicine for drug delivery or paints and coatings. The tri-block polymer poly(methyl methacrylate)-poly(n-butyl acrylate)-poly(methyl methacrylate) (PMMA-PnBA-PMMA) was heated and stirred with 2-ethyl-1-hexanol to create a polymer gel. Through the use of a rheometer, a shear stress …

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Synthesis And Thermoelectric Properties Of Cusbs2, Tianyue Gao, Haiyu Fang, Yue Wu Aug 2014

Synthesis And Thermoelectric Properties Of Cusbs2, Tianyue Gao, Haiyu Fang, Yue Wu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Copper antimony sulfide, CuSbS2 nanoparticles have a large potential of being a good thermoelectric material because they are made up of earth abundant elements. Thermoelectric materials can convert thermal energy into electricity, so that the wasted energy can be saved. Also, by using this earth abundant material, we can make thermoelectric materials much cheaper. The hypothesis of this study is that CuSbS2 could have a large Seebeck coefficient, one of the most important factors of thermoelectric materials, because of the complexity of its band structure. The other hypothesis is that thermal transport could be significantly suppressed through nanostructuring. There are …

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The Role Of Metal Oxide Layers In The Sensitivity Of Lactate Biosensors Subjected To Oxygen-Limited Conditions, Elizabeth Andreasen, Lia Stanciu, Aytekin Uzunoglu Aug 2014

The Role Of Metal Oxide Layers In The Sensitivity Of Lactate Biosensors Subjected To Oxygen-Limited Conditions, Elizabeth Andreasen, Lia Stanciu, Aytekin Uzunoglu

The Summer Undergraduate Research Fellowship (SURF) Symposium


Amperometric lactate biosensors are used to detect lactate concentration in blood and tissues, which is integral in identifying cyanide poisoning, septic shock, and athletic condition. The construction of lactate biosensors with high sensitivity, selectivity, and stability is imperative to diagnose and determine these medical conditions. Lactate detection is currently limited to oxygen-rich environments due to the fact that oxygen is a limiting factor in the lactate reaction. To circumvent this problem, researchers have developed mediators or alternate, oxygen-free enzymes to improve sensitivity. In our study, ceria (CeO2) with high oxygen storage capacity (OSC) was introduced to the enzyme …

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In Vitro Assessment Of Laser Sintered Bioactive Glass Scaffolds With Different Pore Geometries, Krishna C. R. Kolan, Albin Thomas, Ming-Chuan Leu, Greg Hilmas Aug 2014

In Vitro Assessment Of Laser Sintered Bioactive Glass Scaffolds With Different Pore Geometries, Krishna C. R. Kolan, Albin Thomas, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The pore geometry of bioactive glass scaffolds intended for use in bone repair or replacement is one of the most important parameters that could determine the rate of bone regeneration. The pore geometry would also affect the mechanical properties of the scaffolds and their rate of degradation. Scaffolds with five different architectures, having ~50% porosity, were fabricated with silicate (13–93) and borate (13–93B3) based bioactive glasses using a laser sintering process. An established, late-osteoblasts/early-osteocytes cell line was used to perform cell proliferation tests on the scaffolds. The results indicated that the cells proliferate significantly more on the scaffolds which mimic …

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A Mechanical Testing Methodology For Additive Manufacturing Processes, Sujitkumar Dongare, Todd E. Sparks, Joseph William Newkirk, Frank W. Liou Aug 2014

A Mechanical Testing Methodology For Additive Manufacturing Processes, Sujitkumar Dongare, Todd E. Sparks, Joseph William Newkirk, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Most additive manufacturing processes are layer-by-layer deposition, thus its mechanical properties could be very different than those made from traditional manufacturing processes. This paper summarizes a mini-tensile testing methodology for additive manufacturing. Research concerning the tensile testing of metallic material has been conducted and test methods have been defined. It encompasses the methods for determination of yield strength, yield point elongation, tensile strength, elongation, and reduction of area. The study of positional variation and cooling-rate dependency in case of additive manufacturing proves to be expensive and time consuming with the full-size test specimens. Thus, this paper discussed a technique for …

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Investigation Of Forged-Like Microstructure Produced By A Hybrid Manufacturing Process, Romy Francis, Joseph William Newkirk, Frank W. Liou Aug 2014

Investigation Of Forged-Like Microstructure Produced By A Hybrid Manufacturing Process, Romy Francis, Joseph William Newkirk, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser Metal Deposition (LMD) is an additive manufacturing technique for manufacturing complex near net shaped components. The grain size of the typical deposition microstructure in case of Ti-6Al-4V can range between 100µm-600µm, which is much larger than that of forged-like microstructures. Friction Stir Processing (FSP) has been investigated as a method for surface modification to form refined microstructure at the surface of the Ti-6Al-4V components manufactured from the LMD method. Integration of FSP and LMD can greatly improve the product properties. Friction stir processing of the laser deposited Ti-6Al-4V deposits was performed and optimum processing parameters were obtained using this …

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Make Or Buy Analysis Model Based On Tolerance Design To Minimize Manufacturing Cost And Quality Loss, Cucuk Nur Rosyidi, Reza Rizkichani Akbar, Wakhid Ahmad Jauhari Aug 2014

Make Or Buy Analysis Model Based On Tolerance Design To Minimize Manufacturing Cost And Quality Loss, Cucuk Nur Rosyidi, Reza Rizkichani Akbar, Wakhid Ahmad Jauhari

Makara Journal of Technology

In a manufacturing company, manufacturing costs, or component prices, and tolerance will affect the price and the quality of a product. Companies must produce high-quality products with low manufacturing costs in order to keep their products competitive in the market; however, it is difficult to produce a high-quality product with a low manufacturing cost. Companies have difficulties in determining the components to be produced using their own manufacturing facilities (make) or outsourced to their suppliers (buy). Hence, a make or buy analysis is needed to minimize the manufacturing costs and quality loss and to determine the optimum alternative regarding make …

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Observation Of Tunneling Effects In Lateral Nanowire Pn Junctions, Sri Purwiyanti, Arief Udhiarto, Daniel Moraru, Takeshi Mizuno, Djoko Hartanto, Michiharu Tabe Aug 2014

Observation Of Tunneling Effects In Lateral Nanowire Pn Junctions, Sri Purwiyanti, Arief Udhiarto, Daniel Moraru, Takeshi Mizuno, Djoko Hartanto, Michiharu Tabe

Makara Journal of Technology

As electronic device dimensions are continuously reduced, applied bias conditions significantly change and the transport mechanisms must be reconsidered. Tunneling devices are promising for scaled-down electronics because of expected high-speed operation and relatively low bias. In this work, we investigated the tunneling features in silicon-oninsulator lateral nanowire pn junction and pin junction devices. By controlling the substrate voltage, tunneling features can be observed in the electrical characteristics. We found that the minimum substrate voltage required for tunneling to occur in pn junctions is higher as compared with pin junctions. The main cause of these effects relies in the difference between …

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Digestibility Of Betung Bamboo Fiber Following Fungal Pretreatment, Widya Fatriasari, Wasrin Syafii, Nyoman J. Wistara, Khaswar Syamsu, Bambang Prasetya Aug 2014

Digestibility Of Betung Bamboo Fiber Following Fungal Pretreatment, Widya Fatriasari, Wasrin Syafii, Nyoman J. Wistara, Khaswar Syamsu, Bambang Prasetya

Makara Journal of Technology

This research evaluated the effect of fungal pretreatment of betung bamboo fibers and enzymatic- and microwaveassisted hydrolysis on the reducing sugar yield. The enzymatic hydrolysis of the pretreated biomass was carried out with cellulase and 10 and 20 FPU/g of substrate in a shaking incubator at 50 °C and 150 rpm for 48 h. The sulfuric acid concentration used in the microwave-assisted acid hydrolysis was 1.0, 2.5, and 5%, either with or without the addition of activated carbon. Microwave irradiation (330 Watt) was applied for 5–12.5 min. The yield of reducing sugar was better with the microwave-assisted acid hydrolysis, and …

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Argon Ion Irradiation Effect On The Magnetic Properties Of Fe-Al2o3 Nano Granular Film, Setyo Purwanto, Isao Sakamoto Aug 2014

Argon Ion Irradiation Effect On The Magnetic Properties Of Fe-Al2o3 Nano Granular Film, Setyo Purwanto, Isao Sakamoto

Makara Journal of Technology

We studied the effect of Argon (Ar) ion irradiation on Fe-Al2O3 nanogranular thin film. X-ray diffraction (XRD) patterns show that the ion dose might promote the growth of the Fe2O3 phase from an amorphous phase to a crystalline phase. The magnetic and magnetoresistance properties were investigated using a vibrating sample magnetometer (VSM) and a four point probe (FPP). The results suggest that percolation concentration occurred at the 0.55 Fe volume fraction and with a maximum magnetoresistance (MR) ratio of 3%. The present MR ratio was lower than that of previous results, which might be related to the existence of the …

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Adjustable Resonance Frequency Of Rf-Mems Capacitor By Using Comb- Drive Actuators: A Design Approaches, Agus Santoso Tamsir, Sandy Tannu Wijaya, Dato’ Burhanuddin Yeop Majlis Aug 2014

Adjustable Resonance Frequency Of Rf-Mems Capacitor By Using Comb- Drive Actuators: A Design Approaches, Agus Santoso Tamsir, Sandy Tannu Wijaya, Dato’ Burhanuddin Yeop Majlis

Makara Journal of Technology

The needs of smaller size RF varactor is a must today, and MEMS comes to be the potential one. In this paper we proposed an adjustable resonance RF-MEMS varactor by using comb-drive actuators placing in each side of the square movable plate. In our preliminary simulation, we found that the device can work properly but some constraints comes such as the dominancies of harmonic resonance frequencies that influences into the nominal capacitances. Therefore for the next step of development we have to find out the window of the structural dimension for a certain spans and a certain operating frequencies.

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Properties Of Lignin From Oil Palm Empty Fruit Bunch And Its Application For Plywood Adhesive, Lucky Risanto, Euis Hermiati, Yanni Sudiyani Aug 2014

Properties Of Lignin From Oil Palm Empty Fruit Bunch And Its Application For Plywood Adhesive, Lucky Risanto, Euis Hermiati, Yanni Sudiyani

Makara Journal of Technology

Lignin from lignocellulosic biomass is a potential biopolymer for wood adhesive. The aims of this study were to characterize lignin isolated from the black liquor of oil palm empty fruit bunch fiber pretreated with steam explosion in alkaline conditions and to examine the bond quality of aqueous polymer isocyanate (API) adhesive prepared from lignin, natural rubber latex (NRL), and polyvinyl alcohol (PVA) as base polymers with isocyanate crosslinkers. Lignin was precipitated from the black liquor by adding hydrochloric acid; then the precipitate was separated by filtration, thoroughly washed with water up to pH 2 and pH 5, and dried. The …

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Electron Emission Characteristics Of Multi-Gated Field Emitters, Hidenori Mimura, Yoichiro Neo, Toru Aoki, Tomoya Yoshida, Masayoshi Nagao Aug 2014

Electron Emission Characteristics Of Multi-Gated Field Emitters, Hidenori Mimura, Yoichiro Neo, Toru Aoki, Tomoya Yoshida, Masayoshi Nagao

Makara Journal of Technology

We have developed a multi-gated field emitter (FE) such as a quadruple-gated FE with a three-stacked electrode lens and a quintuple-gated FE with a four-stacked electrode lens. Both the FEs can focus the electron beam. However, the quintuple-gated FE has a stronger electron convergence than the quadruple-gated FE, and a beam crossover is clearly observed for the quintuple-gated FE.

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