bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk Analysis and Evacuation Research on Crowded Students for Colleges and Universities' Emergencies
Authors: Zhou Yan , Wei Jin Yu
Published: June 2010

This paper analyzes psychological and behavioral characteristics of the crowd when unexpected events happen, and combined with psychological factors, using methods of safety analysis, from the perspective of people, objects and management, analyzes causes of group accidents. Then, based on analysis above, this paper establishes a risk model, analyzes factors which affect evacuation time and risk of crowded students and finds out fundamental causes. Finally, using methods of safety management and safety education, from three aspects of hardware facilities, emergency evacuation management, and daily management, reasonable and practicable measures and advice are put forward, and are applied combined with an example.
A Multipath Secure Routing Protocol Based on Malicious Node Detection in Wireless Sensor Networks
Authors: Yao Lan , Gao Fu Xiang , Zhao Zhi Bin
Published: June 2010

It is a significant challenge to design a secure routing protocol for wireless sensor network (WSN), because a WSN has dynamic topology, limited energy, confined computing ability and small memory size. This study explores the algorithm of ensuring security in routing layer for a WSN. In this paper, a multipath secure routing protocol for flat network--MDMP is proposed. Symmetric encryption and asymmetric encryption are exploited to encrypt and authenticate data in the network. Furthermore, malicious nodes will be detected out and isolates. Experiments show that MDMP provides effective immunity to a variety of attacks in WSN and better network performance.
Application Incompatible Element in Mixed Fast Multipole Boundary Element Method
Authors: Gui Hai Lian , Huang Qing Xue , Tian Ya Qin , Chu Zhi Bing
Published: June 2010

Based on fast multipole boundary element method (FM-BEM) and mixed variational inequality, a new method named mixed fast multipole boundary element method (MFM-BEM) was presented in this paper. In order to improve calculation time and accuracy, incompatible elements as interpolation functions were used in the algorithm. Elements were optimized by mixed incompatible elements and compatible elements. On the one hand, the difficult to satisfy precise coordinate was avoided which caused by compatible elements; on the other hand, the merits of MFM-BEM were retained. Through analysis of example, it was conclusion that calculation time and accuracy were improved by MFM-BEM, calculation continuity was also better than traditional FM-BEM. With increasing of degree of freedom, calculation time of MFM-BEM grew slower than the time of traditional FM-BEM. So MFM-BEM provided a theoretical basis for solving large-scale engineering problems.
A Multi-Dimensional Query Scheme in Structured Overlays
Authors: Zhang Ming , Yang Jin Qiu
Published: June 2010

Structured peer-to-peer (P2P) systems are creating a large proportion of network traffic in today’s Internet. Peer-to-peer systems enable access to data spread over an extremely large number of machines. A P2P system typically involves thousands or millions of live peers in the network. Multi-dimensional data indexing has received much attention in a centralized database.
In this paper, we propose and evaluate a multi-dimensional searching scheme in structured P2P networks. We present the design and implementation of a peer-to-peer index service for high dimensional data that is capable of handling complex queries. We design a VibIndex scheme in structured P2P overlay networks. We analyze this scheme’s performance and present simulation results. Our simulation results demonstrated the benefits of the proposed system and show that the approach is able to search efficiently.
An Efficient Blind Image Deblurring Algorithm
Authors: Xiao Su , Han Guo Qiang , Wo Yan , Yao Hao Wei
Published: June 2010

This paper presents a novel algorithm which concerns with the fast implement of blind image deblurring with a well-reconstructed original image. Firstly, we model both the original image and the blur utilizing the harmonic model in the Sobolev image space, based on which, the prior distributions of them are obtained; Secondly, the Gamma distribution is used as the prior distributions of the unknown parameters to incorporate more prior knowledge for blind image deblurring; Finally, we estimate the original image, the blur and the unknown parameters simultaneously and iteratively by the evidence analysis method. The experimental results show the efficiency and the competitive performance compared of the proposed algorithm with existing blind image deblurring methods.
Man-Machine Interface of Electric Power Test System Design Based on VI
Authors: Luo Dong Fang , Wen Xin Ling
Published: June 2010

With the implementation of electric power market, it is a difficult problem to provide the high quality and safety electric power, so, the electric power quality test is a key to solve it. Now, many electric power test system is designed by traditional single chip microprocessor with many disadvantages, we present a kind of method to realize based on virtual instrument (VI). System mainly designs upper PC management and test homepage index sub-system made by LabVIEW platform of VI software in this paper, aiming at disadvantage of existing test system without needed authority login module and management man-machine panel. This paper introduces part of system design method and practical result in detail. This system has stronger transplantation to other system because of modular design, which has broad practicality and application prospect.
Properties and Constructing of a Kind of Four-Dimensional Vector Wavelet Packets According to a Dilation Matrix
Authors: Yu Yu Min , Zhu Yu Qing
Published: June 2010

In this paper, we introduce a sort of vector four-dimensional wavelet packets according to a dilation matrix, which are generalizations of univariate wavelet packets. The definition of biortho-
gonal vector four-dimensional wavelet packets is provided and their biorthogonality quality is researched by means of time-frequency analysis method, vector subdivision scheme and functional analysis method. Three biorthogonality formulas regarding the wavelet packets are established. Finally, it is shown how to draw new Riesz bases of space from these wavelet packets. The
sufficient condition for the existence of four-dimensional wavelet packets is established based on the multiresolution analysis method.
The Characteristics of Affine Bivariate Pseudoframes of Subspace Associated with a Bivariate Filter Functions
Authors: Yu Yu Min
Published: June 2010

Frame theory has been the focus of active research for twenty years, both in theory and applications. In this work, the notion of the bivariate generalized multiresolution structure (BGMS) of subspace is proposed. The characteristics of bivariate affine pseudoframes for subspaces is investigated. The construction of a GMS of Paley-Wiener subspace of is studied. The pyramid decomposition scheme is obtained based on such a GMS and a sufficient condition for its existence is provided. A constructive method for affine frames of based on a BGMS is established.
The Characterization of a Kind of Vector-Valued Multivariate Wavelet Packets with Composite Dilation Matrix
Authors: Xia Yin Hong , Li Hua
Published: June 2010

In this article, the notion of a kind of multivariate vector-valued wavelet packets with composite dilation matrix is introduced. A new method for designing a kind of biorthogonal vector- valued wavelet packets in higher dimensions is developed and their biorthogonality property is inv-
-estigated by virtue of matrix theory, time-frequency analysis method, and operator theory. Two biorthogonality formulas concerning these wavelet packets are presented. Moreover, it is shown how to gain new Riesz bases of space by constructing a series of subspace of wavelet packets.
Existence and Designment of Filter Banks of Biorthogonal Vector-Valued Wavelets with Three-Scale Constant Factor
Authors: Gao Hong Wei , Ding Li Ping
Published: June 2010

In this work, the notion of vector-valued multiresolution analysis and biort-
ogonal vector–valued wavelets is introduced. The existence of compactly supported biorthogonal vector-valued wavelets associated with a pair of biorthogonal compactly supported vector-valued scaling functions is investigated. A new method for constructing a class of biorthogonal compactly supported vector-valued wavelet functions is presented by using multiresolution analysis and matrix theory.
The Properties of Orthogonal Nonseparable Four-Dimensional Wavelet Packets
Authors: Liu Yong Jian
Published: June 2010

In this article, the notion of orthogonal nonseparable four-dimensional wavelet packets, which is the generalization of orthogonal univariate wavelet packets, is introduced. A new approach for constructing them is presented by iteration method. The orthogonality properties of four-dimensional wavelet packets are discussed. Three orthogonality formulas concerning these wavelet packets are estabished.
The Development of Multifunctional Inverter Power
Authors: Feng Shu Ling , Wu Chong , Hu Ming , Long Wei
Published: June 2010

A multifunctional inverter welding machine with the functions of DC gas tungsten arc welding, argon tungsten pulsed arc welding, manual arc welding and air plasma arc welding gather in integral whole is introduced in this work. In whose development, the theory of half-bridge series resonant inverter is used as the basis, while the fast SCR as the inverter. When in the situation of welding, full-wave rectification is used, with a working voltage of 36V; while in the situation of cutting, bridge rectifier is used, with a working voltage of 100V~125V. According to a large number of experiments and tests in the development process, the correctness of the mathematical modal of the fast SCR inverter is verified, and a new method of inverter circuit parameter design is obtained. By which, the theoretical basis is provided for the development of inverter welding machine.
A Robust Trust Model Based on Group for P2P Environments
Authors: Zhang Guang Hua , Chen Zhen Guo
Published: June 2010

A robust trust model based on group for P2P environments-RobustGroup is put forward, which measures trust values based on the group relationship between requesting peers and serving peers. Trust’s aging time and peers’ similarity are introduced with weights for direct trust and indirect trust being dynamically adjusted in trust calculation against critical issues affecting trust evaluation such as false feedback, incentive and penalty, Whitewashing behavior, dynamic trust. Simultaneously service control policies are implemented on the basis of groups, and peers’ initial trust is determined by behavior in “silent time”. The simulation shows that the proposed model has advantages in successful requests and system overhead over the existing P2P trust models.
Environmental Performance Measurement for Green Manufacturing Program Based on BP Neural Network
Authors: Wang Qiu Lian , Li Cong Bo
Published: June 2010

To make the environmental performance measuring system a useful inspective and supervisory tool during the life cycle of a Green Manufacturing (GM) program, a measure system is presented. It includes three primary indexes corresponding to the GM program life cycle, which are fundamental construction level, application level and continuous improving level. And 19 secondary measures are subdivided, too. After that, the values of the measures are determined involving qualitative and quantitative index. And then Back Propagation Neural Network (BPNN) is applied to evaluate the environmental performance of GM programs in enterprise, in which 10 samples are used to train the measuring model with Matlab 7.0, and the data are selected from the Internet and digital library. The environmental performance evaluation of a machine tool company in Chongqing shows the effectiveness and validity of the model, and this method can be applied in industrial enterprises while implementing GM.
Bioactive Glass Scaffolds with Hierarchical Structure and their 3D Characterization
Authors: Jones Julian R. , Lee Peter D.
Published: June 2010

Bone tissue has evolved into hierarchical three-dimensional structures with dimensions ranging from nanometres to metres. The structure varies depending on the site in the body, which is dictated by the loading environment. Medically, bone is one of the most replaced body parts (second only to blood) but replicating these complex living hierarchical structures for the purpose of regenerating defective bone is a challenge that has yet to be overcome. A temporary template (scaffold) is needed that matches the hierarchical structure of native bone as closely as possible that is available ‘off the shelf’ for surgeons to use. After implantation the scaffold must bond to bone and stimulate not only three dimensional (3D) bone growth, but also vascularisation to feed the new bone. There are many engineering design criteria for a successful bone scaffold and bioactive glass foam scaffolds have been developed that can fulfil most of them, as they have a hierarchical porous structure, they can bond to bone, and they release soluble silica species and calcium ions that have been found to up-regulate seven families of genes in osteogenic cells. Other ions have also been incorporated to combat infection and to counteract osteoporosis. Their tailorable hierarchical structure consists of highly interconnected open spherical macropores, further, because the glass is sol-gel derived, the entire structure is nanoporous. The macropores are critical for bone and blood vessel growth, the nanopores for tailoring degradation rates and protein adsorption and for cell attachment. This chapter describes the optimised sol-gel foaming process and how bone cells respond to them. Whatever type of scaffold is used for bone regeneration, it is critically important to be able to quantify the hierarchial pore structure. The nanopore size can be quantified using gas sorption, but to obtain full information of the macropore structure, imaging must be done using X-ray microtomography and the resulting images must be quantified via 3D image analysis. These techniques are reviewed.
Generating Porous Ceramic Scaffolds: Processing and Properties
Authors: Deisinger Ulrike
Published: June 2010

For tissue regeneration in medicine three-dimensional scaffolds with specific characteristics are required. A very important property is a high, interconnecting porosity to enable tissue ingrowth into the scaffold. Pore size distribution and pore geometry should be adapted to the respective tissue. Additionally, the scaffolds should have a basic stability for handling during implantation, which is provided by ceramic scaffolds. Various methods to produce such ceramic 3D scaffolds exist. In this paper conventional and new fabrication techniques are reviewed. Conventional methods cover the replica of synthetic and natural templates, the use of sacrificial templates and direct foaming. Rapid prototyping techniques are the new methods listed in this work. They include fused deposition modelling, robocasting and dispense-plotting, ink jet printing, stereolithography, 3D-printing, selective laser sintering/melting and a negative mould technique also involving rapid prototyping. The various fabrication methods are described and the characteristics of the resulting scaffolds are pointed out. Finally, the techniques are compared to find out their disadvantages and advantages.
Bioactive Composites Based on Calcium Phosphates for Bone Regeneration
Authors: Navarro Melba , Planell Josep A.
Published: June 2010

Bone problems affect millions of people across the world. In fact, musculoskeletal conditions such as joint pathologies, fractures related to osteoporosis, back pain, serious injuries and different sorts of bone diseases and disabilities are among the most common causes for hundreds of millions of people worldwide suffering acute and severe long-term pain and becoming physically handicapped. It has been reported that over 100 million Europeans are affected by different bone related problems and suffer chronic musculoskeletal pain, while in the US musculoskeletal problems affect over 40 million people aged 45 years and older. It is expected that the percentage of population affected by musculoskeletal conditions will double by the year 2020. Although morbidity is low, they have a major effect on disability, medical costs and patient quality of life [1,2]. Thus, bone defect treatments represent a significant medical and socioeconomic challenge.
Carbon Nanotubes: A Solution for Processing Smart Biomaterials
Authors: Vila M. , Manzano Miguel , Vallet-Regí Maria
Published: June 2010

In the recent years the driving force for technological change in many respects has shifted towards the design and process of materials that offer a set of responses to external stimuli or environmental conditions. These materials are called “smart materials”. Such responses are designed to fulfil the range of scenarios to which a material or structure may be exposed providing them with a particular functionality. These materials are not only useful because of their structural, chemical, physical or mechanical properties; they can also perform an action within a process. It has been described that smart structures exhibit one or more of the following features; they can act as sensors or actuators within a structural material or bonded in the surface; or they have controllable capabilities that permit to respond to the stimuli according to a prescribed function. These materials become intelligent when they have the ability to respond intelligently and autonomously to changing conditions. There are lots of possibilities within the term functional “smart materials” but in all of them, the term is used to describe systems which respond to a stimulus in a useful and predictable manner. Nowadays it is widely known the useful capability of, piezoelectric, electro-optic, magnetic, electro-mechanic materials, etc…that respond to stimuli such as, electric or magnetic fields, stress, temperature, moisture or pH. These multifunctional character and capability of biomaterials makes them suitable for a big number of applications in every order of human activity, from photochromic lenses for sunglasses to military and aerospace uses. They are already a big part of the market in the engineering industry.
Drug Targeting and other Recent Applications of Magnetic Carriers in Therapeutics
Authors: Silva Amanda Karine Andriola , Silva Erica Lira , Carvalho Juliana Fernandes , Pontes Thales Renan Ferreira , Neto Rafael Pereira de Araújo , Carriço Artur da Silva , Egito Eryvaldo Sócrates Tabosa
Published: June 2010

. Aqueous suspensions containing small magnetic particles have been increasingly used in biosciences and biotechnology. Magnetic particles develop magnetic polarization and magnetophoretic mobility, and because of such unique properties, these carriers may be eligible candidates for delivering drugs to specific sites within the body. Their special properties also allow other uses, such as those in embolization, radioisotope delivery, magnetic cell tracking for monitoring cell therapy, magnetofection, and hyperthermia. This review focuses on a discussion about magnetic particles, the properties and fate of magnetic carriers, the methods used to produce and characterize them, and their other uses in biotechnology.
High Resolution Electron Microscopy: A Powerful Tool to Characterize Nanotubes
Authors: Ruiz-González M.L. , González-Calbet José María
Published: June 2010

On the landscape of the nanoscience and nanothecnology carbon nanotubes (1) have played an important role on the development of 1D materials. They consist of single (SWCNT) or multi (MWCNT) layers of graphene cylinders arranged around a central hollow. In the case of the SWCNT the size distribution is narrow (1-2 nm) while it is broader for MWCNT (2-25 nm) exhibiting a constant separation between layers, nearly equal to that of graphite-layer spacing (0.34 nm). In both cases, the length extends up to several microns. These characteristics provide large external and internal surfaces making both functionalization and filling processes very attractive for potential performances in several areas like electronic, spintronic, or drug release
Parametric Study of Ablation Depths for Different Optical Glasses Using High Fluence Laser Induced Plasma Assisted Ablation (LIPAA)
Authors: Hamdani A.H. , Ahmed W. , Ansar A. , Akhter R. , Farooq W.A. , Aslam M.
Published: June 2010

A 40W Nd:YAG laser has been used to carry out parametric study the etching depth (ablation depth) for different optical glasses using stainless steel, brass and silver as target materials by Laser Induced Plasma Assisted Ablation (LIPAA) process. A maximum ablation depth of 38m for fused quartz has been achieved with stainless steel as target material with a high ablation rate of 565nm/pulse. A surface roughness of 120nm has been measured for fused quartz with stainless steel as target.
Microstructural and Magnetic Properties of a Fe-Co-Ni-Al-Ti-Cu Alloy
Authors: Akbar S. , Ahmad Z. , Farooque M.
Published: June 2010

The present work describes the development of Fe-Co-Ni-Al-Ti-Cu permanent magnets. Magnetic and microstructural studies were carried out using microscopy, magnetometery and X-ray diffraction techniques. The results indicate that both microstructural and magnetic properties are sensitive to the heat treatment conditions. Magnetic properties in the studied alloys could be improved by controlling the annealed state microstructure and by efficiently aligning and elongating the nano-structured ferromagnetic α1 particles in <001> crystallographic directions. The best magnetic properties in the alloy Fe-34.7Co-15.3Ni-8.3Al-5.4Ti-3.9Cu is obtained as coercive force (Hc) of 1528Oe, residual magnetic induction (Br) of 7105G, saturation magnetization (Bs) of 19060G and maximum energy product ((BH)max) of 3.3MGOe.
Development of NdFeB Magnet through Hydrogen Decrepitation
Authors: Akhtar S. , Haider A. , Ahmad Z. , Farooque M.
Published: June 2010

Neodymium based magnets are the powerful permanent magnet of today. This paper will discuss iron based rare earth magnets. NdFeB sintered magnet material has been developed. The magnets are produced by powder metallurgy route involving hydrogen decrepitation technique for making fine powder. After melting and casting, the NdFeB alloy is subject to hydrogen atmosphere. Hydrogen slowly absorbs into the solid alloy and makes it brittle, which upon milling becomes fine powder. Hydrogen is then removed by placing the powder at temperature around 800°C under vacuum. Then the powders are pressed under isostatic conditions and sintered at temperature range of 1020–1050°C. Post sintering is done at 800°C and 580°C followed by quenching. Energy product in the range of 8 MGOe is achieved.
TEM Study for Strengthening Mechanisms in Elgiloy
Authors: Qureshi I.N. , Rani S. , Yasmin F. , Farooque M.
Published: June 2010

Elgiloy is Co based alloy (40wt%Co, 20wt%Cr, 15wt%Ni, 14wt%Fe and 7wt%Mo). It was strengthened by cold work and is capable of additional hardening by aging. The effects of solution treatment, cold working and age-hardening on the microstructure of elgiloy were investigated using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). As rolled strips were solution treated at 1065°C/1hr. These solution treated strips were then reduced 50% by cold rolling. After cold-deformation both є-hcp phase and fcc deformation twins are also considered to coexist at room temperature. The cold worked strips were then age hardened at (450-600)°C. The age hardened strips showed formation of additional є-phase (via α f c c є h c p transformation).
Metallurgical Characterization of Duplex Steel by Non Destructive Techniques
Authors: Khan S.H. , Khan Aamer Nusair , Mahmood K.
Published: June 2010

This paper describes the application of eddy current and ultrasonic velocity technique for the study of cold rolled duplex steel. Samples are cold rolled up to 80 percent and then tested for X-Ray diffractrometeric analysis, hardness testing, ultrasonic longitudinal velocity and for eddy-current testing. It was observed that eddy current impedance and longitudinal velocity is affected due to variation in micro-structure induced by cold working. It is suggested that eddy current and ultrasonic velocity techniques are useful tools for the characterization of duplex steel during cold working operation.
Improvement in Mechanical Properties of High Concentration Particle Doped Thermoset Composites
Authors: Ahmed N. , Khan Mohammad Bilal
Published: June 2010

The paper relates to high concentration particle doped composites based on thermosetting polymer systems in which the sequential addition of particles of certain size distribution is followed by curing and casting of the slurry to form a thermoset composite. Conventionally, at a threshold of beyond 90% of particles by weight of the polymer using triglyceride, the mechanical properties of the composite exhibit a sharp decline. The present research mitigates this behavior by incorporating a unique combination of cross-linking agents in the base polymer to impart exceptional mechanical properties to the composite. More specifically, the base polymer consists of butadiene, with triglyceride as cross-linking agent together with hydroxy-alkane as the chain extension precursors, when tune to the appropriate level of hard segment ratio in the polymer. An added advantage according to the present work resides in the analytical nature of butadiene pre-polymer as opposed to natural product; traditional composites based on natural sources are hampered by their inconsistent chemical composition and poor shelf life in the fabricated composite. The thermoset composite according the present research exhibits superior tensile strength (200-300 psi) properties using particle loading as high as 92% by weight of the fabricated composite as measured on a Tinius Olsen machine. Dynamic Mechanical Testing reveals interesting combination of storage and loss moduli in the fabricated specimens as a function of optimizing the thermal response of the viscoelastic composite to imposed vibration loading.
Transpiration Cooling Assisted Ablative Thermal Protection of Aerospace Substructures
Authors: Khan Mohammad Bilal , Iqbal N. , Haider Z.
Published: June 2010

Ablatives are heat-shielding materials used to protect aerospace substructures. These materials are sacrificial in nature and provide protection primarily through the large endothermic transformation during exposure to hyper thermal environment such as encountered in re-entry modules. The performance of certain ablatives was reported in terms of their TGA/DTA in Advanced Materials-97 (pp57-65) (1). The focus of this earlier research resided in the consolidation of interface between the refractory inclusion and the host polymeric matrix to improve thermal resistance. In the present work we explore the scope of transpiration cooling in ablative performance through flash evaporation of liquid incorporated in the host EPDM (Ethylene Propylene Diene Monomer) matrix. The compression-molded specimens were exposed separately to plasma flame (15000 C) and oxyacetylene torch (3000 C) and the back face transient temperature is recorded in situ employing a thermocouple/data logger system. Both head on impingement (HOI) and parallel flow (PF) through a central cavity in the ablator were used. It is observed that transpiration cooling is effective and yields (a) rapid thermal equilibrium in the specimen, (b) lower back face temperature and (c) lower ablation rate, compared to conventional ablatives. SEM/EDS analysis is presented to amplify the point.
Comparative Study for the Design of Optimal Composite Pressure Vessels
Authors: Butt A.M. , Waheed-ul-Haq Syed
Published: June 2010

Composite pressure vessels require special design attention to the dome region because of the varying wind angles generated using the filament winding process. Geometric variations in the dome region cause the fiber to change angels and thickness and hence offer difficulty to acquire a constant stress profile (isotensoid). Therefore a dome contour which allows an isotensoid behavior is the required structure. Two design methods to generate dome profiles for similar dome openings were investigated namely Netting Analysis and Optimal Design method. Both methods assume that loads are carried by the fiber alone (monotropic) ignoring the complete composite behavior. Former method produced a lower dome internal volume and a higher fiber thickness as compared to the later optimal design method when studied against different normalized dome opening radiuses. The optimal dome contour was studied in ANSYS with a trial design. The dome was considered to have transversely isotropic property with a dome contour based on monotropic model. While investigating the dome with non linear large displacement finite element analysis, the dome still exhibited isotensoid behavior with transverse isotropic material assignment. Elliptic integrals were used to generate the optimal dome contours and hence elliptic dome contours were formed which were isotensoid in nature with complete composite representation.
MOCVD Grown Quantum Dot-in-a-Well Solar Cells
Authors: Majid A. , Fu L. , Jagadish C. , Tan H.
Published: June 2010

This paper reports the experimental work on the characterization of quantum dot-in-well (DWELL) solar cell grown by metal-organic chemical vapor deposition (MOCVD) without employing any post-growing optimization like antireflection coating and metal grid. The structure of the 10-layer DWELL solar cells is studied by cross-sectional transmission electron microscopy (TEM). Room temperature photoluminescence (PL) spectra show strong quantization at 1178.5 nm with a linewidth of 79.9 nm. External quantum efficiency spectra show enhancement in the spectral response of the photocurrent with respect to the reference quantum dot cell (without DWELL structure). In spite of the reduction in conversion efficiency due to poor collection of current in external circuit compared to reference quantum dot cell it show the improvement in open circuit voltage.
Development of Perovskite Based Ceramics for Ultrasonic Applications
Authors: Khalid M. , Shuaib M. , Khan A.A.
Published: June 2010

Perovskite crystal structure is found in many ionic solids like CaTiO3, BaTiO3 and PZTs. In this structure off-center position of cations in oxygen octahedral causes polarization and produces direct and indirect piezoelectric responses in ceramic materials that are suitable for many ultrasonic applications. Lead Zirconate Titanate (PZT) with formulae Pb0.91Sr0.09(Zr0.53 Ti0.47)O3 was prepared by conventional mixed oxide route with an objective to achieve dense piezoelectric sintered components exhibiting adequate properties for sonar applications. Dielectric and ferroelectric/piezoelectric properties of PZT are strongly influenced by composition, homogeneity and porosity in the densified part. To achieve the objective of a good homogenous and dense body, the initial powders and the final product were characterized by SEM equipped with EDX, XRD and Particle Size Analyzer during each processing step. Electrical characterization was carried out by LCR meter and Transducer Analyzer. Planetary Mill instead of a conventional ball mill was employed for initial mixing and grinding of calcined powder. Properties achieved by sintering at 1200°C for 2 hours in lead rich atmosphere were Dielectric Cosntant (K) = 1440, Tangent Loss (Tanδ) = 0.0062, Charge Coefficient(d33) = 335 pC/N, Coupling Coefficient (k) = 0.37 and density = 7.55 g/cm3. After sintering the observed grain size was 2-3 µm with clean grain boundaries. To ascertain the effects of accelerated ageing on dielectric and piezoelectric properties, final product was first heated at 50°C for 5 days and then at 100°C for 3 days. The results showed that dielectric and piezoelectric properties were stabilized to a large extent by heating at 100°C for 3 days. The ageing data for 9% Sr doped PZT is not reported earlier, therefore, it would help in great deal in predicting the performance of component in service
Finite Element Based Design of Piezoelectric Vibration Damper
Authors: Bhatti J.S. , Pasha R.A.
Published: June 2010

Vibration control using combination of piezoelectric material and electrical circuits can remove the vibration energy from the host structure. The need for passive damping techniques arises to avoid the complexities and energy requirements associated with other vibration control techniques. Passive damping technique for reduction of vibration of structures by introduction of shunted piezoelectric patch is presented in this study. Finite element analysis is performed for a cantilever beam with shunted piezoelectric patch on it. The prediction of the model is validated against experimental published results. The obtained results demonstrate the feasibility of using piezoelectric patches with passive shunting as effective means for damping out the vibrations. The aim of this research work is the advancement of the coupled field analysis for structural vibration control with advanced methodology and to promote the design and analysis activities in the field of passive vibration control techniques using smart structures. Results obtained showed up to 86% reduction in the amplitude of the host structure which shows good agreement with published experimental results.
Effect of Vacuum Arc Melting/Casting Parameters on Shrinkage Cavity/Piping of Austenitic Stainless Steel Ingot
Authors: Kamran J. , Sarwar M. , Feroz M.
Published: June 2010

Shrinkage cavity/piping at the end of the solidified ingot of steels is one of the most common casting problem in 316L austenitic stainless steel ingot, when consumable electrode is melted and cast in a water-cooled copper mould by vacuum arc re-melting furnace. In present study an effort has been made to reduce the size of shrinkage cavity/ piping by establishing the optimum value of hot topping process parameters at the end of the melting process. It is concluded that the shrinkage cavity/piping at the top of the solidified ingot can be reduced to minimum by adjusting the process parameters particularly the melting current density.
Inkjet Printing of Catalyst-Inks on Si Wafers and the Subsequent Synthesis of Carbon Nanotubes by Chemical Vapour Deposition
Authors: Mansoor M. , Kinloch Ian , Derby Brian
Published: June 2010

The production of substrates coated with carbon nanotubes (CNTs) in well-defined patterns is desirable for sensor applications. In the present work, nickel based catalytic inks were prepared and printed on silicon substrates using inkjet delivery. Subsequently, the substrates were subjected to calcination and chemical vapour deposition for the growth of aligned CNTs. Scanning electron microscopy, transmission electron microscopy and Raman spectroscopy were used to characterize the CNTs. Various concentrations and formulations of ink preparations were studied to investigate the effect of these parameters on the growth and structure of the CNTs.
Substrate Temperature Effect on Optical Constants of Gd2O3 Thin Films
Authors: Wasiq M.F. , Nadeem M.Y. , Chollet Franck , Atiq S.
Published: June 2010

Effect of substrate temperature on lanthanide oxide material Gd2O3 thin films deposited by e-beam evaporation has been reported in the present work. Optical properties and surface morphology of as deposited films have been measured using spectrophotometry and atomic force microscopy respectively. Optical constants such as refractive index, extinction coefficient, band gap and Urbach energy have been determined by analysis of experimentally recorded absorption, transmittance and reflection data in wavelength range 200-800nm. Optical band gap energy shows decreasing while Urbach energy shows increasing behavior with increasing temperature. Extinction coefficient and refractive index with varying wavelengths are also calculated. Surface topographies of all samples are studied by atomic force microscope (AFM) and root mean square (RMS) value of roughness is observed increasing with increasing substrate temperature.
Analytical Solutions and Finite Element Modelling of Deep Drawing Process for Cylindrical Metal Cups
Authors: Supasuthakul Jeerachai , Hodgson Peter , Weiss Matthias , Yang Chun Hui
Published: June 2010

Analytical modelling of deep drawing process is of value in preliminary process design to illustrate the influence of major variables including friction and strain hardening on punch loads, cup dimensions and process limits. In this study, analytical models including theoretical solution and a series of finite element models are developed to account for the influences of process parameters including friction coefficient, tooling geometry and material properties on deep drawing of metal cups. The accuracy of both the theoretical and finite element solutions is satisfactory compared with those from experimental work.
Strip Casting by a Single Roll Caster Equipped with a Scraper
Authors: Nakamura Ryoji , Akitsu Kazuya , Yamabayashi Takanori , Kumai Shinji , Watari Hisaki
Published: June 2010

A scraper was equipped to a single roll caster to improve the free solidified surface. The scraper contacted to the free solidified surface at the constant force. The some mount of semisolid layer at the surface was removed and the surface became flat. The scraper was made from the mild steel plate. The mild steel plate was covered by the insulator paper to prevent the cooling of the melt by the plate. The melt pool was made on the roll by the side dam plates, back dam plate and the scraper. Therefore, a tip or a nozzle was not needed. The AA5182 and AA6022 aluminum alloy were cast. The as-cast strips could be cold rolled. The microstructure of as-cast strip was not uniform at thickness direction. However, the microstructure became uniform after the cold rolling and the annealing.
Parameter Design for the Counter-Blanking Process Using the Finite Element Method and the Taguchi Approach
Authors: Thipprakmas Sutasn
Published: June 2010

There is an increasing demand for high quality metal stamped parts. In general, burr formation is the main defect found subsequent to the blanking process. This defect must be strictly removed specifically for consumer products in order to prevent any kind of injury to the operators. Such a removal process results in an increase of the production cost. The unique merit of the counter-blanking process focuses on fabricating the burr-free blanked parts. However, it is difficult to control the numerous process parameters involved in this process in order to achieve the burr-free blanked parts. Thus, this study aims at investigating the process parameter design for the counter-blanking process by means of combining the finite element method (FEM) and statistical analysis techniques, including the Taguchi method and the analysis of variance (ANOVA) techniques. The results indicate that the process parameter of blanking clearance has a major influence on the die-roll formation features of the burr-free blanked part, respectively followed by the punch penetration depth and the same level of influence of the two process parameters of punch and die diameters in the second step. To conclude, this technique could be applied as a tool to achieve good quality of the burr-free blanked parts by optimizing the value of the process parameters and their favorable combinations.
Modeling the Vertical Spincasting of Large Bimetallic Rolling Mill Rolls
Authors: Studer Léo , Detrembleur Sylvain , Dewals Benjamin J. , Pirotton Michel , Habraken Anne Marie
Published: June 2010

In order to take into account the dynamic effects of molten metal during solidification, a methodology is presented to interface a metal solidification solver (coupled thermal mechanical metallurgical finite elements solver) with a specifically developed flow dynamics solver. (flow dynamics and thermics finite volume solver) The numerical set of tools is designed to be used for the simulation of bimetallic hot rolling mill rolls vertical spincasting. Modeling the industrial process for these products imply certain specifications on the numerical methods used, mainly due to the size of the geometrical domain, low Rossby & Ekman numbers, and a high Reynolds number.
Draw Bending of Load-Adapted Sheet Metal Profiles
Authors: Rosenberger Jürgen , Suesse Dietmar , Hübner Sven , Ulbricht Volker , Behrens Bernd-Arno
Published: June 2010

The draw bending process represents an alternative for the flexible and inexpensive production of open sheet metal profiles. This paper introduces the draw bending process with its functional principle and specifies the most important characteristics. It includes the key results of several research projects dealing with draw bending to prove the applicability of this technique to produce customized profiles.
Dry Turning of Rotor Steel 26NiCrMoV145 Using Multilayer Coated Cemented Carbide Tools
Authors: Guo Guo Giang , Li Jun Li , An Qing Long , Chen Ming , Liu Gang , Zhang Yun Shan
Published: June 2010

Rotor steel 26NiCrMoV145 has been widely employed in aerospace and power industry because of its unique properties. As to this new material that used widely in important places, it is worth studying its machinability. An experiment was carried out to study the cutting forces and tool wear mechanism during high speed dry turning using multilayer Al2O3 coated carbide insert. The orthogonal test was chosen, cutting forces were measured. SEM analysis has been carried out on worn tools to determine the tool wear mechanisms. Crater wear and coating peeling could be found in every cutting speed. Flank face wear appears smooth when cutting speed increases. At last, an optimization of the cutting condition was suggested when considering of material remove rate, cutting forces and tool wear.
Experimental Study on Cutting Characteristics for Buttress Thread Turning of 13%Cr Stainless Steel
Authors: An Qing Long , Guo Guo Giang , Zheng X.H. , Chen Ming , Liu Gang , Zhang Yun Shan
Published: June 2010

13%Cr stainless steel has good comprehensive performance, which makes it suitable to work under the condition of high temperature, high pressure and corrosive environment, such as petroleum industry. It can be used as materials of petroleum pipes with buttress thread. Buttress thread turning is a heavy-load machining, which places high requirement on the cutting tool. Based on the cutting characteristics of buttress thread, the machinability of 13%Cr stainless steel is studied by turning experiments. Two kinds of inserts with different geometries were employed in buttress thread turning experiments. Experimental results show that less cutting force, longer tool life, better chip curling effect and surface quality was acquired for the insert with rake angle of 12° , clearance angle of 3° and chip-curling groove during 13%Cr stainless steel buttress thread turning process.
Finite Element Simulation of Chip Formation during High-Speed Peripheral Milling of Hardened Mold Steel
Authors: Tang De Weng , Wang Cheng Yong , Hu Ying Ning , Song Yue Xian
Published: June 2010

The modeling and simulation of chip formation during high speed milling of hardened mold steel are systematically studied by the Finite Element Analysis (FEA). The modified Johnson-Cook’s constitutive equation for hardened mold steel is introduced. Comparing to the experimental results, the simulated results of cutting force, chip morphology, effective stress and cutting temperature in deformation zones of high speed peripheral milling indicate good consistence and the models established can be used to accurately predict the behavior of hardened mold steel.
Simulation and Optimal Selection of Pitch Angles Distribution for Variable Pitch Angles Helix End Mills
Authors: Huang Pan Ling , Li Jian Feng , Sun Jie
Published: June 2010

In the paper, a static milling force model for variable pitch mills was built, and the milling forces were simulated. The resultant force and its frequency spectra of variable pitch mills were analyzed compared with that of uniform pitch mills. It is shown that the standard deviation (SD) of frequency spectra amplitudes for variable pitch mills is extremely lower than that of uniform pitch mills. Through simulation for SD of frequency spectra amplitudes affected by the different cutting parameters, a pitch angles distribution of variable pitch helix end mills with lower SD of frequency spectra amplitudes was selected.
Fuzzy Chatter Stability Lobes Model in Milling
Authors: Chen Ming , Zhang Xiao Hui , Ming Wei Wei
Published: June 2010

Based on the conventional chatter stability model, stability Lobes diagram in die & mould steel milling system is obtained. The derived diagram can be divided into two independent regions by a Lobes curve: absolutely stable and instable region. In fact, it is more reasonable that there should be a transition stage between the stable and instable state. That is to say, grade of stability (GOS) should be in a closed interval [0, 1], rather than Boolean logic. Due to the different stability sensibilities for different order Lobe curve in milling system, there should be different widths of transition belts for different order curve. Thus, with the help of Sigmoid transfer function widths of each order Lobe curve are studied. Finally, the fuzzy chatter stability is implemented by an adjustable slope coefficient.
Cutting Performance of Al2O3/TiC/TiN Nanocomposite Tools
Authors: Liu Han Lian , Huang Chuan Zhen , Zou Bin
Published: June 2010

A multi-scale and multi-phase nanocomposite ceramic cutting tool material Al2O3/TiC/TiN(LTN) with high comprehensive mechanical properties has been successfully fabricated by means of adding micro-scale TiC and nano-scale TiN particles. The cutting performance and wear mechanisms of this advanced ceramic cutting tool were researched by turning two kinds of hardened steel 40Cr and T10A respectively. Compared with the commercial ceramic tool LT55, LTN showed a superior wear resistance with certain machining parameters. The machining tests indicated that the new materials tool is suitable for continuously dry cutting of hardened steel with high hardness at high speed.
Investigation on Chip Morphology and Surface Quality in High-Speed Ball-End Milling of Inconel 718
Authors: Sonawane Harshad A. , Joshi Suhas S.
Published: June 2010

The ball end milling process, commonly used for generating complex shapes, involves continuous variation in the uncut chip dimensions, which depends on the cutter geometry and the machining parameters. The proposed analytical model evaluates the undeformed and the deformed chip dimensions including chip length, width and thickness. The undeformed and deformed chip dimensions, is a function of cutter rotation angle, instantaneous cutter radius, helix angle, and other processing parameters. The surface quality, in the form of surface roughness, during high-speed ball end milling of Inconel 718 is also analysed in this paper.
Effect of MQL Liquids on Surface Integrity when High Speed Drilling Titanium Alloy
Authors: Rahim Erween Abdul , Sasahara Hiroyuki
Published: June 2010

This paper describes the results of application of different MQL liquids (synthetic ester and palm oil) to high speed drilling of Ti-6Al-4V. The investigation was focused on the surface integrity of the machined surface. It was found that palm oil could be a viable alternative to the synthetic ester for MQL liquid application.