bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Neutral Point in Water Distribution Network Pipes with Variable Discharge on Route
Authors: Sarbu Ioan , Ostafe Gabriel
Published: March 2014

Distribution networks are an essential part of all water supply systems. Distribution system costs within any water supply scheme may be equal to or greater than 60% of the entire cost of the project. The reliability of supply is much greater in the case of looped networks. The pipe networks have concentrated outflows or uniform outflow along the length of each pipe. In some pipes with variable discharge of a looped distribution network, water velocity could be reversed between its extremities. Thus, it is a water stall point denominated neutral point in which the discharge is null. In this paper a mathematical model for the determination of water stall point location in the pipes with distributed consumption is developed. This model has been implemented in a computer program for PC microsystems. Numerical example will be presented to demonstrate the accuracy and efficiency of the proposed model.
The Thermal Insulation Performance of Envelope Construction of Residential Housing – A Case Study of Detached Houses in Yilan, Taiwan
Authors: Hsieh Hung Ren , Lee Chih Hao
Published: March 2014

This research aims to study the design and thermal insulation performance of detached houses in Taiwan through the analysis of 55 detached houses. The research shows that 85% of detached houses are built using reinforced concrete (RC) construction, and the rest mostly using lightweight steel framing (LSF) construction. The thermal insulation performance of envelope construction of RC housing is poorer than LSF housing. More than 80% of the case study sample could not meet the roof thermal insulation requirements of Taiwans latest regulations on housing building energy saving. The most commonly used thermal insulation materials are polystyrene board, glass wool and rock wool, which are nearly all applied in LSF housings for the internal thermal insulation layer or the structural body layer of envelope construction. Polystyrene board has the widest range of use, including both internal and external thermal insulation layers of the envelope construction. If improving thermal insulation performance of the common envelope construction concluded from case study samples to meet Taiwans latest regulations on housing building energy saving, of the savings on air-conditioning energy during the summer could potentially be 11.5%. However, above improvement project is not economically beneficial due to the too long payback period.
Study on Reactive Ion Etching of Vanadium Oxide Thin Film by Taguchi Method
Authors: Gou Jun , Tai Hui Ling , Wang Jun , Gu De En , Wei Xiong Bang , Jiang Ya Dong
Published: March 2014

A high selectivity patterning technology of vanadium oxide (VOx) thin film was suggested in this paper. VOxthin film was etched through a photoresist (PR) mask using Cl/N based gases in a reactive ion etching (RIE) system. Taguchi method was used for process design to identify factors that influence the patterning and find optimum process parameters. Experimental results suggested that RF power was the largest contribution factor for VOxetch rate, PR selectivity and uniformity on 6 inch diameter wafer. Uniformity and PR selectivity were improved by introducing a small amount of N2. High resolution and low roughness patterning transfer was achieved with a non uniformity of 2.4 %, an VOxetch rate of 74 nm/min, a PR selectivity of 0.96, a Si3N4selectivity of 5 and a SiO2selectivity of 10.
Immobilization Efficiency Evaluation by Using Tessier, TCLP and SBET Method for As, Cu and Pb Contaminated Soils
Authors: Xiao Han , Yang Wan Qiu , Shen Liang
Published: March 2014

In this paper, Tessier sequence extract procedure (SEP), toxicity leaching procedure (TCLP) and simple bioaccessibility extraction test (SBET) were employed to evaluate the immobile efficiencies for As, Cu and Pb contaminated soils. Experimental results indicated that the TCLP was efficient to extract the most active part heavy metal and evaluate the risk of the samples; the Tessier method divided heavy metals in soils to different fractions. Monitoring the changes of different fractions during the immobilizing procedure could help fully understand the mechanism of stabilization. The SBET method simulated the human digest system, thus it could be used to evaluate the risk changes to human during the immobilizing process; and to reveal the potential risk of chemical stability. In our project, these three evaluate method should be utilized properly to help accessing the risk, electing suitable immobilizing method and evaluating the efficiency of stabilization.
Property Evaluation of Polyester/Cotton Woven Fabrics Made with Stainless Steel Weft Yarns
Authors: Lou Ching Wen , Chang Yuan Jen , Shiu Bing Chiuan , Sie Ming Chun , Lin Jia Horng
Published: March 2014

Smart textiles have been widely discussed as a result of a fact that wearable technique has been used in healthcare, sports, tele-rehabilitation, and military fields. Textiles are characterized as comfortable, and thus suitable for long-term wearing, and therefore this study proposes to prepare humidity-sensitive textiles with electrical conductivity. Woven manufacturing is used in order to provide the textiles with desired mechanical properties of the woven fabrics that use high strength polyester (PET) fibers as the warp yarn, and cotton fibers and stainless steel fibers as two weft yarn types. Cotton fibers are water absorbent, while stainless steel fibers are electrically conductive and thus are able to provide sensing function. The humidity-sensitivity of the textiles relies on electrical conductivity; this study observe the fabric structure, water contact angle, and electrical conductivity of the fabrics in order to fabricate mechanically strong and humidity sensitive smart textiles.
Manufacture Technique and Mechanical Properties of Kevlar/PET Composite Fabrics
Authors: Lin Jia Horng , Lin Mei Chen , Chen An Pang , Lou Ching Wen
Published: March 2014

With the advancement of industry, the utilization of cushion package to apply on the products of civilian, sports, electric, precise equipment increases extensively, which are brittle and vulnerable that need to be protected. In the research, the Recycled High Strength PET fiber, Recycled Kevlar fiber and low melting PET fiber are selected as materials, which the content of Recycled Kevlar fiber is stationary. The composite nonwoven fabric was manufactured by non-woven processing and subsequently estimated its stab-resistant strength and air permeability. The composite nonwoven fabric was being heat treatment which can make low melting point PET fiber bonding with other fibers in order to enhance the mechanical property of composite nonwoven fabric.
The Influence of Hot Pressing Temperatures in Needle Punching Nonwoven
Authors: Lou Ching Wen , Hsing Ya Lan , Hsing Wen Hao , Lin Jia Horng
Published: March 2014

Non-woven textile industry in an emerging field, with the process short, high yield, low cost and wide source of raw materials, but also has excellent performance of many functions on, making non-woven over the past half century gained textiles attention and consumers of all ages. The proportion of the world of non-woven fiber material used in the product, 85% in rayon ,and the other 15% in natural fibers, polyester fibers which accounted for the largest proportion of use. The experiment uses a low melting point polyester fiber (LPET) 20%, three-dimensional hollow curly polyester fiber (TPET) and recycled far infrared fiber (REPET) 40% each as the basic conditions change pressing temperature 100 °C-140 °C, in order to observe and compare the effects of temperature on the non-woven fabric, this experiment tests including air permeability, tensile strength testing, infrared testing and SEM, respectively in different hot pressing temperature, each of the non-woven hot pressing temperatures sample go through microscopic to analysis for non-woven with the hot temperatures strong reason to improve or decline with hot temperature of air permeability.
Bottom-Up Fabrication of Optical Metamaterials
Authors: Zhao Wei
Published: March 2014

A metamaterial is an artificially structured material which attains its properties from the unit structure rather than the constituent materials. Here, artificially designed silver dendritic structure was used as basic cells to fabricate metamaterials working at IR frequency range, silver dendritic structure was prepared in the mixture of F127 and PEG, then assembled on glass substrate by self-assembly process and further fabricated into sandwich-like metamaterials with Indium-Tin-Oxides (ITO) glass. Micro-morphology of the dendrites array was examined by scanning electron microscopy. These complex-structured metamaterials exhibit pass-bands at IR frequencies, and show slab focusing effect subsequently.
New Intelligent and Efficient Pesticide Sprayers in Mechanical Manufacturing Engineering
Authors: Ma Deng Yun , Li Tao Tao , Sun Ke , Wang Jun Liang , Li Ling Wan , Zhang Hao , Chen Ding Fang
Published: March 2014

In view of the traditional low mechanization,degree of automation and lack of humanization etc, a n-ew intelligent and efficient pesticide spraying machine can be created to add pesticide to cotton.Completed parametric design of the device's virtual prototype by SolidWorks,and we apply virtual prototyping technologyto key parts to go on dynamics simulation analysis,to verify the reasonableness of this mechanism design and correctness of the function to achieve.
AE Characterization of Cracking Mode in Sandstone Uniaxial and Brazilian Tests
Authors: Zhang Xiao Hu , Liu De Chao , Ren Xiao Long
Published: March 2014

Laboratory results from sandstone Brazilian splitting tests and uniaxial compression tests based on acoustic emission (AE) monitoring indicated that the acoustic emission parameters analysis method can be applied to analyse the characteristics of acoustic emission and to classify the crack modes in rock materials. It concluded that more than 99 per cent of the whole cracking signals in Brazilian tests were classified as tensile mode, and no shear cracks occurred. And more than 65 per cent of the AE signals in uniaxial tests were tensile-shear crack mode, along with about 30 percent of tensile mode and 5 percent of shear mode, and shear cracks only occurred in the unstable crack extension stages; tensile-shear cracks are the main crack modes in the crack stable extension stage.
Research on Mechanical Manufacturing with Creative Design and Combination of 3D Mechanical Manipulator Based on Fischertechnik
Authors: Tao Zhu , Wu Tao , He Chun Hua
Published: March 2014

This paper describes the design, composition and application of Fischer creative model. Combined with production practice, the Fischertechnik model is used to establish the structure of the 3D manipulator system. The results of model meet design requirements. Practice shows that the application of Fischer creative combination model is quickly and easily to build medium-sized machinery and equipment. It significantly reduces the build cycle and system debug, which could help designers quickly implement a variety of design intent and improvements. Fischer creative mix model plays an important role in teaching experiment and engineering applications.
Research on Mechanical Dynamics with a Use of a Vehicle Wake Generating Device Simulation and Design
Authors: Lu Ti Wen , Hu Wen , Li Ling Wan , Chen Ding Fang
Published: March 2014

There is rich automotive wake and wind resource on the highway. Power can be used for power generation, supply of electrical equipment or the highway into the grid .The paper proposes a new wind vertical axis wind generator. According to the actual conditions ,the important institutions are needed to optimize device emulation. The dynamics of shaft has a major impact on the stability of the power plant's work. Use ANSYS to provide a reference for further optimization agency. Radial pendulum balls mounted to the whole device can be stable on the shaft buffer.
Comparative Study of Ink-Jet Color Proofing Systems Based on Color Management
Authors: Cheng Chang Xian , Liang Yan Mei
Published: March 2014

Abstract. In order to study the color matching effect of ink-jet printing press under different color management systems. I applied EFI and ORIS series color management soft wares separately to the same Epson ink-jet printer and optimized the proofing with exploring the most reasonable settings. After that, I will compare the gamut and color difference in a special color management module, and also make a contrast with a standard color gamut to check the color matching effect. The results show that the average color differences of the two soft wares are all below 1.0. However, differences measured by ORIS is lower, falling to 0.5 only, which implies the proofing under ORIS color management is more similar to the presswork and more stable.
Influence of Structural Relaxation on Compressive Plasticity of Zr64.13Cu15.75Ni10.12Al10 Bulk Metallic Glass
Authors: Gu Jian Sheng , Bo Hui Feng
Published: March 2014

Structural relaxation through isothermal annealing below the glass transition temperature was conducted on a Zr64.13Cu15.75Ni10.12Al10bulk metallic glass. Differential scanning calorimetry was used to quantify enthalpy differences between the as-cast and relaxed samples, which were then related to average free volume differences. The influence of structural relaxation on plasticity was examined. While the free volume decreasement can be clearly observed between the as-cast and relaxed samples, structural relaxation is not accompanied by severe embrittlement.
An Orthogonal Experimental Analysis of WEDM-HS of Al2O3 Particle-Reinforced Aluminum Alloy 6061 with 10-Vol% Al2O3
Authors: Liu Jiang Wen , Wu Yong Zhong
Published: March 2014

In wire electro-discharge machining with an extremely high travelling speed of wire electrode (WEDM-HS), the emulsion is used as working liquid. Because there exists a functional electrolyte, the EDM spark can operate under a relatively large spark gap size condition, and this would facilitate the removal of machined debris. An investigation has been made into the machining feasibility when WEDM-HS has been employed to process Al2O3particle reinforced aluminum alloy 6061 with 10-vol% Al2O3(10ALO). And the material removal rate (MRR) has been examined in this study. Since there are many factors that can influence the MRR in the WEDM-HS process, in order to determine which is the most important factor and to optimize the machining parameters, the relative importance of the various machining parameters on material removal rate was established by utilizing an orthogonal experimental analysis. The results of the analysis suggest that to achieve a high MRR for particulate reinforced aluminum 6061 with 10-vol% Al2O3, the duty cycle is the most influential factor among current, pulse duration and duty cycle. And the impact of the different factors follows the sequence of duty cycle > current > pulse duration.
Study on Elastic Modulus of Porous Ti Coatings by Three-Point Bending and Indentation Measurement
Authors: Fu Qing Shan , Yang Rui Song , Li Ming Tian
Published: March 2014

Elastic modulus of a coating is an important property for design and use of the coating. At present, many methods have been put forward to evaluate the coating elastic modulus. However, each methods has special property, which make the elastic moduli from them are different. In the study, elastic modulus of a porous Ti coating has been evaluated by three-point bending test and indentation method. The results show that the coating elastic moduli from the two different methods agree well, which can reflect the uniformity of the pore structures of the porous coating. Meanwhile, the little deviations among the different test points of indentation method could reflect the uniformity of the coating structure partly.
The Potential of Starch as an Eco-Friendly Binder in Injection Moulding of 316L Stainless Steel for Medical Devices Applications
Authors: Wahab Nor‘aini , Omar Mohd Afian , Nordin Nor Amalina , Sauti Rosliza
Published: March 2014

Two starch/wax based binders were formulated for metal injection moulding of 316L stainless steel. The formulations difffer in term of the starch type which substitute the backbone polyethelene. Feedstock having powder loading of the stainless steel powder up to 65 vol.% can be injection moulded successfully. Solvent debinding was performed in water at a temperature of 60°C for 3 hours and followed by immersion n-heptane for duration of 2 hours to remove the residual wax. The remaining binder was thermally extracted at 4500 with heating rate of 3°C/min, with no defects. The parts were then sintered in vacuum atmosphere within a temperature range of 1300°C to 1380°C. Approximately, 6.8 g/cm3theoretical density, hardness of 188.8 HV and tensile strength of 229.3 MPawere achieved for cassava starch/wax based binder while rice starch/wax based binder possessed 8.6g/cm3theoretical density, hardness of 385 HV and tensile strength of 462.1 MPa.
Optimum Heat Treatment of Extrusion Die Steel
Authors: Qamar Sayyad Zahid
Published: March 2014

Commercial hot extrusion is a billet-by-billet cyclic process, with high thermal and mechanical stresses generated in the die set. The die is a costly piece of equipment, and its long service life is essential for profitable operation. Extrusion dies primarily fail by fracture, wear, and plastic deformation. To avoid early failure, it is essential to have an optimum combination of toughness and hardness in the die. This combination can be achieved through a judicious mix of heat treatment and surface hardening. Experiments were conducted to determine mechanical properties of H13 steel after various heat treatment sequences. Heat treatment strategy is described in detail, and effect of different tempering temperatures on fracture toughness and hardness of the tool steel is reported. Changes in mechanical properties are also related to the variation in microstructure. For use in commercial hot extrusion dies, optimum tempering temperature for H13 steel was found to be near 525-600oC, for the best combination of toughness and hardness.
Basic Study on Creep Properties of Eucalyptus Wood
Authors: Ma Yuan Rong , Li Xian Jun , Deng Biao , Luo Ying She
Published: March 2014

The study tested the short-term bending creep curves of Eucalyptus Plantation Wood under different loads, moisture contents and temperatures, analyzed the influence of load, moisture content and temperature on creep of Eucalyptus. Guided by the rheological theory, the study adopted the Burger rheological model to do the curve fitting and solved the model parameters. A defect found from Burger model in simulating long-term creep properties of wood was preliminary discussed and remedied. The equivalence of creep test and relaxation one was discussed.
Monitoring of Draft Beer Fermentation Process by Electronic Nose
Authors: Phetchakul Toempong , Sutthinet Chalin
Published: March 2014

The draft beer fermentation process was monitored by using electronic nose. The system used the seven types of generally commercial metal oxide gas sensor in array. The selected process was one of the commercial processes and the data were gathered every hour for 10 day process which was 240 steps. It was processed for monitoring the chemical reaction for quality control. The results showed the good difference of the chemical reaction of the each day very clearly. The signature processing showed the variance 98.78 %, 96.55 % of the first component (PC1) and 2.3 % of the second component (PC2), which was sufficiency for data explanation in 2D plot. It would be useful for production process to ensure a quality standard.
Preliminary Study of Oil Palm Decanter Cake Natural Polymer Composite (OPDC-NPC)
Authors: Adam Muhammad Aqif , Sulaiman Alawi , Said Che Mohd Som , Som Ayub M. , Bahruddin Azhari Samsu , Mokhtar Mohd Noriznan
Published: March 2014

Palm oil industry produces huge amount of oil palm decanter cake (OPDC). Currently it is not yet commercialized however due to its characteristics, it can be used to produce oil palm decanter cake natural polymer composite (OPDC-NPC). NPC is a type of material made by combining natural fiber with polymer. Therefore the objective of this paper is to produce NPC from OPDC and then determine its mechanical and physical properties such as elasticity, stiffness, tensile strength and water absorption rate. The OPDC samples were collected from Felda Trolak Palm Oil Mill. Prior to NPC development, the oil was removed from OPDC using hexane soxhlet extraction method. OPDC-NPC was fabricated using molding method where the mixture of 95% polypropylene (PP) and 5% OPDC were mixed using twin-screw extruder. The results showed that OPDC-NPC has an elasticity of 2231 MPa, stiffness of 30 MPa, tensile strength of 32 MPa and water absorption rate of 0.16 % which was slightly better with the other types of fibers.
Rutting Evaluation of Aged Binder Containing Waste Engine Oil
Authors: Nurul Hidayah M. K. , Hainin Mohd Rosli , Hassan Norhidayah Abdul , Abdullah Mohd Ezree
Published: March 2014

The stiffness of aged binder is highly contributed to the workability problem. Rejuvenating agent such as waste engine oil (WEO) is one of the sustainable modifiers that can be used to improve and attain the desired performance of the aged binder. However, concern arises on the consistency of the engine oil properties due to its unknown history usage. This study focused on the rutting properties evaluation of the partial aged binder integrating with engine oil (new and waste sources) using Dynamic Shear Rheometer (DSR). The findings showed that, the addition of WEO affects the rutting performance under ageing condition. From the isochronal curve, the complex modulus, G* of the rejuvenated binder was found lower than the aged binder at un-aged condition. However, after ageing process, the stiffness of the rejuvenated binder was increased and the phase angle, δ decreased obviously compared to virgin binder. The critical temperature of the binder was not differing substantially particularly under ageing. Meanwhile, the ageing index rutting factor (AIRF) clearly summarised that the rejuvenated binder with WEO with higher mass loss more susceptible to ageing.
Air Void Characterisation in Porous Asphalt Using X-Ray Computed Tomography
Authors: Norhidayah Abdul Hassan , Mahmud Mohd Zul Hanif , Ramadhansyah Putra Jaya
Published: March 2014

This study presents the characterisation of the air voids distribution for porous asphalt mixtures compacted using gyratory compactor. The distribution of voids content and voids shape within the porous asphalt were characterised for different nominal maximum aggregate size (NMAS) and specimen height. This is to evaluate the effect of different aggregate size composition and lift thickness on the air voids characteristics of the compacted porous asphalt. Two types of gradations were adopted i.e. Grading A (with NMAS=10 mm) and Grading B (with NMAS=14 mm) and they were fabricated for two different heights (50 and 100 mm). The internal structure was captured using X-ray Computed Tomography and image analysis techniques were used to process and analyse the images. It was found that mixture with coarse aggregate gradation produced larger void size with an elongated shape, which indicates voids connectivity within the mixture compared to fine gradation with more circular and smaller void size.For lift thickness, itacts differentlyfor different aggregate gradations. The specimen produced greater voids connectivity when the fine and coarse gradations were compacted at 100 mm and 50 mm respectively. These show that NMAS and lift thickness influence the mobility of the aggregate particles during compaction which affect the voids formation and determine the effectiveness of the compaction.
Cracking Propagation of Reinforced Concrete Using Polyethylene Terephtalate (PET) Bottles as Fine Aggregate
Authors: Irwan J.M. , Annas M.M.K. , Aeslina A.K. , Othman Norzila , Koh Koh Heng , Asyraf R.M. , Faisal S.K.
Published: March 2014

This paper describes the experimental investigation on the cracking propagation and pattern of reinforced concrete beam containing PET aggregate as fine aggregate that subjected to shear. The replacement ratio of 25%, 50% and 75% were used in this study. Prior to structural test, the materials properties which include the compressive strength test, split tensile test, Modulus of Elasticity test and density were determined. The result obtained showed that the inclusion of PET aggregate reduce the initial loading cracks to 27%, 38% and 46% compared to their corresponding normal concrete ; thus affecting the shear resistance of the structural beam especially the ability of the beam to resist shear via interface friction and interlocking between aggregate.
Corrosion Behavior of WC-Co in High Sulphate Content
Authors: Ismail Azzura
Published: March 2014

Cermet alloys are a combination of ceramic and metal. Therefore, cermets exist in high corrosion resistance in aqueous media. However, because of the nature of cermet alloys, which have a metal and ceramic composition, the corrosion rate is complex to identify. The corrosion attack could be assessed by calculating the corrosion rate or through electrochemistry evaluation. Generally, the corrosiveness of media increased as the anions contents increased. This paper presents the corrosion mechanism of cobalt tungsten-carbide (WC-Co) exposed to a high concentration of sulphate in the salinity of seawater. The solution (media) was prepared according to the same composition as seawater including pH, salinity and dissolved oxygen. The corrosion rate was then identified and the corrosion mechanism revealed. The corrosion rate was identified at 4°C, 20°C, 50°C and 80°C and compared with the corrosion rate of WC-Co in seawater. The results revealed that sulphate has an inhibiting effect that minimises the corrosion attack on WC-Co. The corrosion rate decreased as the sulphate content in seawater increased, and an increase in the temperature increased the corrosion attack on WC-Co.
Resorbable Polymer Membranes for Medical Applications
Authors: Stodolak-Zych Ewa , Łuszcz Anna , Menaszek Elżbieta , Ścisłowska-Czarencka Anna
Published: March 2014

A bioresorbable polymer poly-ε-caprolactone (PCL) was tested in order to obtain porous materials suitable for membranes. The commercial PCL with various molecular weights (2kDa, 60kDa, 80 kDa) but similar polydispersity has been chosen. The membranes were produced by the casting method and the membrane materials underwent microstructure investigation (SEM) to assess the size of pores and an average porosity of the membranes. The membranes permeability was established by means of ultrafiltration. Also wettabilility and basic mechanical properties (such as: tensile strength Rm, Youngs modulus, E) were established. The membranes durability was tested in in vitro conditions (PBS/37°C) by monitoring of changes by means of ion conductivity measurement and changes in the molecular weight (the Ubbelohde method). The porous materials were tested towards biocompatibility, i.e. the membrane was contacted with the osteoblast line of NHOst cells (viability test, cells morphology). Non-perforated PCL foil was used as a reference material. The best physicochemical, mechanical and biological properties of the membranes were observed in case of application of PCL with molecular weight of 60 kDa.
Lightning-Like Charged Jet Cascade in Bubble Electrospinning with Ultrasonic Vibration
Authors: Liu Hong Yan , Kong Hai Yan , Wang Mei Zhen , He Ji Huan
Published: March 2014

Lightning is a natural phenomenon caused by an atmospheric electrical discharge, and lightning strikes are of hierarchical structure. Similar phenomenon is first observed in a charged jet in the presence of a high electrostatic field, the process is widely adopted for fabrication of superfine fibers, and its mechanism of lightning-like charged jet is still unknown. Our observation reveals that a daughter jet can be ejected from the surface of a micro/nanoscale charged jet to form an initial two-stage cascade, whereby the daughter charged jet can reduce size over three orders of magnitude, while at the ultimate stage, the jets have almost same size from several nanometers to dozens of nanometers. The origin of this phenomenon might be central to nanotechnology. Here we demonstrate that an electrostatic field can accelerate a charged jet, and the surface charge repels each other. When the repelling force reaches a threshold to overcome its surface tension, one or more daughter charged jets are ejected from the surface. The daughter jets behave similarly to the initial jet, the process is iterative, creating a lightning-like multi-stage cascade. This observation opens the door to mimicking the lightning to produce two dimensional superfine fiber web with hierarchical structure.
Preparation, Characterization and Ionizing Radiation Protection Properties of Electrospun Nanofibrous Mats Embedded with Erbium Oxide (Er2O3) Nanoparticles
Authors: Liu Fu Juan , Cui Qiu Na , He Ji Huan , Fei Dong Dong
Published: March 2014

Ionizing radiation directly causes serious damage to human health, and a protective system capable of absorbing or reflecting ionizing radiation is required urgently. In this work, electrospun poly (vinyl alcohol) (PVA) and Poly (vinyl Alcohol)/Erbium Oxide (PVA/Er2O3) nanocomposite fibrous mats were fabricated. These PVA or PVA/Er2O3 composite nanofibers were completely characterized using scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Furthemore, air permeability and ionizing radiation protection properties of these mats were also measured. Under a certain constant electropinning condition, the PVA or PVA/Er2O3 composite nanofibers showed an excellent morphology. The ionizing radiation protection capability of nanofibrous mats is considerably improved when incorporated with Er2O3 nanoparticles.
A Brief Introduction to the Development of Biogenic Synthesis of Metal Nanoparticles
Authors: Mondal Samiran , Basu Saswati , Begum Naznin Ara , Mandal Debabrata
Published: March 2014

Though there are a numerous methods for chemical synthesis, biogenic synthesis of nanoparticles offers an attractive alternative to chemical synthesis methods. Therefore scientists are continuously engaged in searching hazard free, environment friendly methods of synthesis of nanoparticles with tailor-made structural properties using benign starting materials. Recently several groups have achieved success in the synthesis of Ag, Au, Pd nanoparticles with specific shape and size using extracts obtained from micro-organisms as well as various plant extracts. It will be a highly interesting problem to modify the procedure to develop green-chemical means of synthesizing “tailor-made” monodisperse nanoparticles of single polygonal particle morphology, exclusively. The main objective of this brief article is to give an idea about the most reliable, cost-effective and environment friendly synthetic protocols for metal nanoparticles of different size, shape, composition, and with a high degree of monodispersity.
Role of Vacancies in Zigzag Graphene Nanoribbons: An Ab Initio Study
Authors: Tarawneh Khaldoun , Al-Aqtash Nabil
Published: March 2014

We have studied the effects of vacancies on the structural, electronic and magnetic properties of zigzag-edged graphene nanoribbons (ZGNRs). Our calculations were carried out using an abinitio density functional pseudopotential computational method combined with the generalized gradient approximation for the exchange-correlation functional. The equilibrium geometries, electronic charge spin density distributions, electronic band structures, and magnetic moments were examined in the presence of single vacancy and double vacancies. Structural optimization showed that vacancies induce substantial structural changes in ZGNRs. We found that introducing vacancies into ZGNR changes the spatial distribution of neighbor atoms, particularly those located around the vacancies. Our calculations showed that the vacancies have significant effect on the magnetization of ZGNR. The calculations showed that the changes in the structural geometry, the electronic structure and the magnetization of ZGNR depend on the location of the vacancies with respect to the ribbon edges. These results suggest that vacancy defects can be used to modify the electronic and the magnetic properties of ZGNR.
Two-Dimensional Isotropic Damage Elastoplastic Model for Quasi-Brittle Material
Authors: Beneš Pavel , Vavřík Daniel
Published: March 2014

Micro-mechanical model for isotropic damage of quasi-brittle material including frictionis presented. Damage is assumed to be isotropic and scalar damage variable is employed . Operatorsplitting method is applied. The article contains derived expressions for derivations necessary forcomputation of coefficients in two dimensions for strain and damage normality rules.
Micromechanical Properties of Polyacrylamide Hydrogels Measured by Spherical Nanoindentation
Authors: Nohava Jiri , Swain Michael , Eberwein Philipp
Published: March 2014

Hydrogels are very compliant materials suitable for tissue engineering in various areas of biological and clinical research. Appropriate and effective application of hydrogels for specific cellular regeneration often requires precise knowledge of their mechanical properties. The present work focuses on measurements of mechanical deformation and creep properties of polyacrylamide hydrogels using a novel indentation system. Four concentrations of polyacrylamide gel were tested under four different loading rates to study the mechanical response of the material to various loading rates. A spherical indenter with large radius was used in the experiments and all indentations were done with the sample completely immersed in water. The results show that higher acrylamide concentration in the gel leads to higher elastic modulus and decrease of creep. Similarly, faster loading rates lead to higher elastic modulus and larger creep during the hold period. The data were analyzed using both Hertzian fit to the loading part and Oliver-Pharr approach to the unloading part. The discrepancy between these two approaches and significant creep behavior are related to the viscoelasticity of the tested materials. This work contributes to understanding the results of instrumented indentation of extremely compliant materials with respect to their viscoelastic properties.
The Effect of PVD Tungsten-Based Coatings on Improvement of Hardness and Wear Resistance
Authors: Horník Jakub , Tondl David , Sachr Pavel , Anisimov Evgenyi , Puchnin Maxim , Chráska Tomáš
Published: March 2014

This article deals with the analysis and evaluation of coatings applications made by Physical vapour deposition on ceramics substrates. Main focus is on the application of tungsten and tungsten nitride coatings for functionally graded materials (FGM). The article focuses on analysis and evaluation of tungsten and tungsten nitride coatings with ceramics substrates. Firstly suitable deposition parameters of W and WN coatings, prepared by magnetron sputtering, were tested. Test coatings on tool steel substrate exhibited high adhesion and good mechanical and technological properties. Both tungsten and tungsten nitride coatings on selected ceramics substrates exhibited good mechanical a technological properties. Properties such as hardness, reduced elastic modulus and wear are discussed for each coating/substrate combination. Both coatings seem to be good candidates for application in field of FGM. The results of the presented experiment shows that the adhesion and the final quality of the coating depends on the type of chemical bond in the coating and in the substrate, and on the ability of the coating to deform plastically.
Influence of Preheating Temperature on the Quality of the Interface between Plasma Sprayed Coatings and Substrate
Authors: Vilémová Monika , Nevrlá Barbara , Matějíček Jiří , Mušálek Radek
Published: March 2014

This study was aimed to investigate the effect of the substrate preheating temperature on the overall quality of the coating/substrate interface. The coatings (stainless steel) were deposited using a water stabilized plasma torch (Institute of Plasma Physics, Prague, i.e. IPP, Czech Republic) on steel substrates. Three sets of samples were prepared under identical spraying and grit blasting condition; substrate preheating temperature was the only parameter which was varied, i.e. preheating to 150°C, 250°C and 350°C. Higher preheating temperature led to a significant increase in the coating adhesion.
Local Characteristics of Ductile Fracture Surface in Spheroidized Steels
Authors: Strnadel Bohumír
Published: March 2014

It is possible to successfully propose the physical-metallurgical and structural conditions for the equilibrium between steel strength and toughness by designing structural parameters which have a positive effect on the relation between local and macroscopic fracture processes. In carbon steels and microalloyed steels for a wide range of technical uses, whose structure after heat treatment consists of a basic matrix of tempered lower bainite with precipitated carbides and sometimes other types of inclusions, toughness is dependent primarily on the size distribution of second phase particles, their volume ratio, and also the strength of the matrix/particle phase boundary and the mechanical properties of structural phases. By modelling and simulating the process of main crack formation during high-energy ductile fracture, it is possible to propose optimum physical-metallurgical and geometric parameters of steel structure in order to achieve the required relation between strength characteristics and toughness. This paper presents an analysis of results achieved in several tasks carried out to predict mechanical properties in ductile fracture, and it outlines potential future developments. The aims are to determine the limit characteristics of mechanical behaviour of structural steels which can be achieved with a view to the current structural situation and technological possibilities, and furthermore to propose future methods for determining relations between microstructure and toughness.
Inspection of Local Influenced Zones in Micro-Scale Aluminium Specimens
Authors: Zlámal Petr , Doktor Tomáš , Koudelka Petr , Fíla Tomáš , Kytýř Daniel , Jiroušek Ondřej , Králík Vlastimil , Němeček Jiří
Published: March 2014

This study is focused on detection and characterisation of influenced zones in micro-scale specimens of aluminium foam after thermal and mechanical loading induced by preparation process for three-point bending test. Two cell-wall specimens were prepared from a slab of aluminium foam and influences of preparation process (machining) and thermal load on local mechanical properties were investigated using nanoindentation. Although the nanoindentation is powerful method for investigation of material properties of small zones, it can be reliably used only to obtain information about elastic properties. Due to limitation of the nanoindentation for reliable measurement of inelastic properties, plastic properties were determined using a set of indirect finite element simulations of nanoindentation tests. The procedure is based on fitting numerical results to experimentally measured force-depth curves.
Application of Small Punch Tests for Screening of Mechanical Properties for T91 Steel
Authors: Lašan Michal
Published: March 2014

The T91 steel is considered a perspective structural material for Generation IV (GEN IV) nuclear reactors components. The operating conditions of GEN IV nuclear reactor, which include higher operating temperatures, higher neutron fluencies and using liquid metals as coolants, constitute new challenges for structural materials validation. To properly assess the impact of radiation, thermal, load and environmental damage the screening test procedures for initial overview of the induced changes of mechanical properties need to be developed and validated. One of the test procedures with potential to be used for the mechanical properties screening is Small Punch test. Small Punch test receive considerable attention since their development in the 1980's. The use of miniaturized test specimen constitutes minimal requirements for the test material and the option of obtaining the test material directly from the component. They have been successfully used on industrial scale for design life extension of components for energy industry in the past. In this paper we address the issue of the Fracture Appearance Transition Temperature (FATT) determination by the means of Small Punch test for the T91 steel, manufactured according to ASTM standard A387-Ed99. The test specimen were manufactured and used for the experiments in a wide range of test temperatures. Multiple levels of deformation energy were used to provide more representative interpretation of the test data. A data fit is applied on the deformation energy – test temperature dependence to obtain the value of FATT from Small Punch test, which is subsequently correlated to the values obtained from testing sub-size Charpy specimens.
The Effect of Microstructural Features on Mechanical Properties
Authors: Anisimov Evgeniy , Manak Jan , Puchnin Maxim , Sachr Pavel
Published: March 2014

Every material is structured in its unique way and has its own recognizable microstructure. There are a number of approaches in establishing the relationship between mechanical properties and microstructure of a material, but none of them is universal and correlation free, probably because of luck of attention to the sub-grain structure. The possibility of calculating the hardness number using only geometric sizes of microstructural formations is discussed in this paper, where the grain is meant to be a container of the two most frequently occurred shapes in the microstructures globula and lamellae.
Non-Destructive Identification of Defects in Power Support Structure Foundations by Means of Acoustic Techniques
Authors: Sadowski Lukasz
Published: March 2014

Prefabricated power support structure foundations are made in prefabrication plants where concrete is laid in layers in moulds. The quality of the prefabricated units depends mainly on proper concrete mixture compaction, which is usually effected by means of immersion vibrators. It happens that when the vibrator is withdrawn too quickly, defects, in the form of, e.g., air voids and zones of insufficiently vibrated concrete, appear. Modern non-destructive acoustic techniques, which in recent years have been increasingly commonly used in the construction industry, are highly suitable for testing concrete elements, particularly prefabricated concrete units. The non-destructive impact-echo technique is particularly useful for determining defect location depth and for locating defective areas.
Electroreduction of Oxygen Using Platinum Nanoparticles Supported on Carbon/Conductive Bipolymeric Nanocomposite Film for Polymer Electrolyte Membrane Fuel Cells
Authors: Narayanamoorthy B. , Balaji S.
Published: March 2014

Synthesis and electrochemical characterization of carbon supported platinum nanoparticles dispersed over Nafion-Polyethylene glycol bipolymeric nanocomposite film (Pt/VC/NP) was attempted for catalyzing the oxygen reduction reaction (ORR) in sulfuric acid medium. The nanocomposite films were surface characterized using Scanning electron microscope, X-ray diffraction pattern, X-ray fluorescence spectroscopy and Atomic force microscopy analyses. The electrochemical behavior was studied using cyclic voltammetry and linear scan voltammetry under static and hydrodynamic conditions to check the catalytic ability of the electrocatalyst films towards ORR. A good correlation was seen between the conductivity of the nanocomposite films from electrochemical impedance spectroscopy and the ORR activity. The higher ORR activity was obtained with the onset potential of 1.08 V vs. RHE and the limiting current density of 1.65 mA/cm2 for 40 wt. % Pt/VC/NP catalyst film. The ORR kinetic and thermodynamic parameters were calculated and compared with standard Pt/C literature values.
Chitosan Based Nanocomposite Materials as Photocatalyst – A Review
Authors: Nithya A. , Jothivenkatachalam Kandasamy , Prabhu S. , Jeganathan K.
Published: March 2014

Heterogeneous photocatalysis is a significant technology for environmental application. Moreover, immobilising an appropriate catalyst on the surface of a natural organic polymer presents a number of additional advantages including low-cost, high catalytic activity and extensive potential reuse for the application of pharmaceutical, biomedical and industrial activities. This review mainly focuses on the role of chitosan based material as photocatalyst on the environmental remediation.
Features of the Magnesium Alloys Corrosion in the Chloride-Containing Media
Authors: Gnedenkov Andrey S. , Sinebryukhov Sergey L. , Mashtalyar Dmitry V. , Gnedenkov Sergey V.
Published: March 2014

A greater corrosion stability of the MA8 (Mg-Mn-Се) alloy as compared to that of VMD10 (Mg-Zn-Zr-Y) magnesium alloy in the chloride-containing solution has been demonstrated using the scanning vibrating probe method (SVP) as well as the methods of optical microscopy, gravimetry and volumetry. It has been established that the crucial factor of the corrosion activity of the samples under study consists in the occurrence of the micro galvanic couples at the samples surface. MA8 alloy contains less amount of the secondary phases (cathodic parts) relative to VMD10. The corrosion rate of the samples with coatings formed by the plasma electrolytic oxidation (PEO) method and composite polymer-containing coatings at the surface of various magnesium alloys has been measured. It has established, that PEO-coating decrease the values of the corrosion rate in several times (more than one order of magnitude for MA8 and more than 2 times for VMD10) in comparison with bare alloys.
Protective Properties of the Nanocomposite Coatings on Mg Alloy
Authors: Gnedenkov Sergey V. , Sinebryukhov Sergey L. , Egorkin Vladimir , Vyaliy Igor E. , Emelyanenko Alexandre M. , Boinovich Lyudmila B.
Published: March 2014

Nanocomposite coatings were obtained by aggregation of nanoparticles from dispersion in decane on the surface of oxide coatings. Oxide coatings on magnesium alloy were formed by plasma electrolytic oxidation in silicate containing electrolyte in bipolar mode. Electrochemical properties and stability of nanocomposite coatings under conditions of prolonged exposure to chloride containing environment were studied by means of electrochemical impedance spectroscopy, potentiodynamic polarization and measurements of contact angles. The coatings possess superhydrophobic properties with the contact angle of 166o ± 3o and the rolling angle of 5o ± 3o. It was found that these nanocomposite coatings reduce the corrosion current of magnesium alloy by more than three orders of magnitude. High stability during immersion in aggressive media is due to a small contact area of the coatings with electrolyte and high adhesion of the hydrophobic agent molecules with the coating.
Electrical Transport Features in Fe3O4/SiO2/n-Si Hybrid Structures
Authors: Vikulov Viktor A. , Dimitriev Artem A. , Balashev Vyacheslav V. , Pisarenko Tatiana A. , Maslov Andrey M. , Korobtsov Vladimir V.
Published: March 2014

The temperature dependencies of the resistivity of planar structures Fe3O4/SiO2/n-Si, with Fe3O4films of different thicknesses, were investigated. In the temperature range below 125 K, an anomalous decrease in the resistivity was observed. This effect is explained by switching of the conductance channel from the Fe3O4film to the inversion layer of Si substrate due to the field-assisted tunneling of carriers through the semi-insulating Fe3O4/SiO2double insulator. Confirmation was obtained by the current-voltage characteristics measured at 80 K. It was found that current-voltage characteristics areS-shaped and correspond to the MIS switch diode.