bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Ferroelectric Domain on Fatigue Fracture Behavior in Piezoelectric Ceramics
Authors: Nakamura Motonori , Sakaki Chiharu , Kimura Masahiko , Konoike Takehiro , Takagi Hiroshi , Shirakihara Kaori , Kimachi Hirohisa , Tanaka Kesisuke
Published: July 2013

Fatigue tests on lead zirconate titanate (PZT) were performed by using single-edge-V-notched specimens under cyclic mechanical loading with or without superposition of a DC electric field. Fatigue life was prolonged by applying a DC electric field to the PZT ceramics. To estimate the domain contribution, fatigue tests on barium strontium titanate (BST) ceramics in both ferroelectric and paraelectric phase were carried out. The fatigue life of the ferroelectric phase was much shorter than that of the paraelectric phase. Comparing the fatigue lives of two PZT ceramics with different values of coercive electric field (Ec) revealed that the fatigue life of the PZT with higher Ec is about one order of magnitude longer than that with lower Ec when the stress-intensity factor of fatigue test is low. It is therefore concluded that non-180°domain switching probably deteriorates the fatigue life of ferroelectric ceramics.
Preparation of Barium Titanate Porous Ceramics and their Piezoelectric Power Generation Property
Authors: Wada Satoshi , Shimura Yoshikazu , Pulpan Petr , Fujii Ichiro , Nakashima Kouichi
Published: July 2013

Barium titanate (BaTiO3) porous ceramics were prepared by conventional sintering method, and their dielectric and piezoelectric properties were measured using 31-resonators. With decreasing sintering temperature, dielectric constant showed a maximum of 5500 at 1300 °C, while piezoelectric constant and elastic compliance increased. These resonators were developed to unimorph-type vibrators and their instantaneous electric powers were measured. As the results, the maximum electric power of 129 μW was measured for the BaTiO3porous ceramics sintered at 1200 °C, and this value was 20 times greater than that for dense BaTiO3ceramics.
Preparation of Bismuth Copper Based Perovskite-Type Ceramics and their Piezoelectric Properties
Authors: Shimamura Atsushi , Fujii Ichiro , Nakashima Kouichi , Kuroiwa Yoshihiro , Wada Satoshi
Published: July 2013

The structural, and dielectric and piezoelectric properties of 0.3BaTiO3- 0.1x(x= Bi (Mg1/2Ti1/2)O3, Bi (Cu1/2Ti1/2)O3, Bi (Cu2/3Nb1/3)O3, (Bi1/2K1/2)(Cu1/3Nb2/3)O3) 0.6BiFeO3ceramics were studied. The relative density of all the samples was more than 94 %. A single perovskite phase was obtained for the samples, and the crystal structure was pseudo-cubic. The Curie temperature ofx=Bi (Mg1/2Ti1/2)O3and Bi (Cu1/2Ti1/2)O3system ceramics was higher than 400 °C. The apparent piezoelectric constantd33* ofx=Bi (Mg1/2Ti1/2)O3, Bi (Cu1/2Ti1/2)O3, Bi (Cu2/3Nb1/3)O3and (Bi1/2K1/2)(Cu1/3Nb2/3)O3system ceramics was 311, 212, 75 and 70 pm/V, respectively.
On Construction Wastes Recycling and its Economy
Authors: Tang Yue Qin
Published: July 2013

This paper addresses problems of aggregate concrete of construction wastes, which were featured as large water absorption, quick slump loss, as well as easy bleeding and low strength of concrete. A comparative analysis by experiment between recycled aggregate concrete and ordinary concrete was made on aspects of water absorbability, compressive strength, slump loss, bleeding rate, drying shrinkage and economic efficiency. It has found possible to preparing the recycled aggregate concrete of high performance through the prewetting recycled aggregate. It is concluded that construction wastes can be recycled by obtaining the optimum mole of preparing recycled aggregate concrete of construction wastes and evaluating their reliability on cost-lefficiency and mechanic capability，thus, it also recycled the limited resources and solve some environment problems.
Design of Sinusoidal Grating Projection Depicts Transmission
Authors: Cheng J.T. , Zhao W.L. , Zhao C. , Wu W.H.
Published: July 2013

The measurement of body contours grating fringe projection technology is the three-dimensional measurement of a hotspot. Basic principle is to be tested based on grating projection three-dimensional object shape; key technology is to enable the generation of sinusoidal grating projection stripes projected onto the measured object. Theoretical sinusoidal intensity stripes should be a phase grating, but such grating is difficult and costly. Therefore, this paper structure of smooth three-dimensional measurement system, the core scanning devices-grating, through the characterization method to design a production, and enable it to project a stripe of light intensity by the sine distribution is given the experimental results. From the start of the study to refine and perfect the final three stages, each stage is accompanied by a large number of experiments. Using Fresnel-Kirchhoff formula. The overall structure of the grating design and the gradual improvement，Achieved good results, And proposed future research ideas and program，Also gives the experimental data and results.
Lightweight Design of PLATE ShearS Bed Based on Topology Optimization and Test Methods
Authors: Wang Yong , Li Kun , Cui Bao Ping , Zhang Zu Fang
Published: July 2013

In order to meet the lightweight design requirements of one swing-type plate shears, the topology optimization method is applied to improve the structure of bed. According to the analysis of the actual working conditions, the reasonable load and boundary conditions are determined. The conceptual model of bed structure is established by using topology optimization method. Lightweight improvement scheme is proposed based on the topology optimization results, and the rationality of scheme is verified by test and analysis. Different parts of the bed are thickened or thinned, and the influences of different thickness of the stiffener on the maximum principal stress, total displacement, displacement in Y direction and weight of bed structure model are analyzed. A reasonable lightweight scheme of shear machine bed is proposed. The weight of the bed is reduced and the lightweight purpose is finally achieved in the case of meeting the requirements of shearing accuracy.
Dynamic Modeling and Simulation Analysis for Rotary Ultrasonic Machining of SiCp/Al Thin-Walled Structure
Authors: Wang Ming , Dong Guo Jun , Zhou Ming
Published: July 2013

SiCp/Al thin-walled structure is processed by rotary ultrasonic machining (RUM). Machining allowance of thin-walled structure is large, manufacturability is bad, and it is vulnerable to vibration to reduce processing quality in machining. Based on analysis of chatter mechanism of RUM, a dynamic model for chatter analyzing and a stability judgment criterion are established and the simulation is conducted for a typical thin-walled component of SiCp/Al composite with time domain analysis method. The simulation results show that machining parameters of RUM could be optimized selected with this model, chatter could be prevented effectively and a good processing effect achieved.
Research on Flow Field Simulation and Experiment of Numerical Control Electrochemical Turning
Authors: Fu Xiu Qing , Xian Jie Yu , Kang Min , Xiao Mao Hua
Published: July 2013

To design the flow field of inner-spraying cathode in NC-ECT, the numerical model was built according to the physical model of the cathode flow channel, and the Computational Fluid Dynamics (CFD) method was applied to solve the numerical model. The velocity and pressure distributions were obtained. The influences of the cathode internal structure on the flow field were analyzed according to the numerical simulation. The relatively good simulation results were obtained by means of the optimization design of the cathode internal structure. Based on the experiment, the accuracy of simulation was verified, and the correction number of the flow field design was reduced in NC-ECT. It is indicated that the CFD method can be applied to guide the optimization design of the cathode structure.
Functionalized Silicate Supported TiO2-ZnO Nanocomposite Film and its Application in Simultaneous Photocatalytic Degradation of Toxic Molecules
Authors: Dhanalakshmi R. , Pandikumar A. , Ramaraj R.
Published: July 2013

The TiO2-ZnO nanocomposite materials ((TiO2-ZnO)NCM) with different molar ratios (Ti:Zn) was synthesized by chemical route and dispersed in functionalized silicate sol-gel matrix (Silicate/(TiO2-ZnO)NCM)). The as prepared Silicate/(TiO2-ZnO)NCM were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The dispersion of the small amount of (TiO2-ZnO)NCM in silicate sol-gel matrix paves the way for the preparation of solid-state thin film photocatalyst which is advantageous for the separation of the catalyst from solution, the substrates and the reaction products. The simultaneous photoinduced oxidation of methylene blue (MB) dye and reduction of Cr (VI) to Cr (III) was examined at different amine functionalized silicate sol-gel embedded (TiO2-ZnO)NCM films. The (TiO2-ZnO)NCM dispersed into the amine functionalized silicate sol-gel matrix (TPDT) exhibited enhanced photocatalytic activity when compared to the (TiO2-ZnO)NCM without the silicate sol-gel. The functionalized silicate sol-gel supported (TiO2-ZnO)NCM is a potential candidate for energy conversion and environment remediation and cleaning applications.
Comparing the SEED Semi-Solid Process to Low Pressure Permanent Mould in the Production of 4mm Thick Aluminum A356 Covers
Authors: Chiesa Franco , Levasseur David , Baril Jocelyn
Published: July 2013

In order to compare the semi-solid SEED casting process to the Low Pressure Permanent Mould process (LPPM), the same part has been produced in aluminium A356 (AlSi7Mg04) using the two methods. The processes were first compared from an operational standpoint: pouring temperature, filling sequence, production rate and mould maintenance. In addition, the metallurgical quality of the castings was evaluated by measuring the tensile properties at 6 locations in the part; the metallographic structures were also compared. Filling and solidification modeling allowed the prediction of the filling sequence and local solidification times everywhere in the casting. The SEED process was generally found to deliver a finer structure, a near net shape casting and a much higher productivity. LPPM parts were more uniform in structural and mechanical properties as verified at 6 locations in the castings.
Energy Efficient Technology for Al–Cu–Mn–Zr Sheet Alloys
Authors: Belov Nikolay A. , Alabin Alex N.
Published: July 2013

The possibility of using alloys of the Al-Cu-Mn-Zr system for obtaining cold rolled sheets directly from cast billets (without homogenization) was investigated. The experimental (SEM, TEM, DSC, mechanical tests, etc.) study and Thermo-Calc software simulation were used for alloy composition optimization. It was shown that optimal structure could be developed in alloys of the following compositional range: 1–2% Cu, 1–2% Mn and 0.2–0.6% Zr. The proposed range of compositions can be recommended for development of new aluminium wrought alloys, which will have two main advantages compared with the commercial alloys of the AA2219 type: i) high tolerance to heating up to 300 °C because of the high amount of Al3Zr and Al20Cu2Mn dispersoids; ii) energy efficient processing, in particular due to the elimination of homogenization, solution treatment and quenching.
Effect of Strain and Strain Rate on the Evolution of Dispersoid Particles in Al-Mn-Fe-Si Alloy during Hot Deformation
Authors: Hill Thomas , Robson Joseph , Kamp Nicolas
Published: July 2013

The development of both dispersoid and constituent particle types during high temperature deformation has been investigated. Using torsion testing, which enables good temperature and strain rate control, the development of particles in terms of individual properties and the overall population has been examined during extended high strain rate deformation. Torsion tests also allow material that has the same thermal history but different levels of strain within a single sample to be compared. Quantitative comparison of particles has been performed using high resolution SEM imaging. Strain has been shown to have an important influence on particle evolution, beyond changing the kinetics of particle evolution alone. It has been demonstrated that the shape of the dispersoids is altered when they are evolving under the action of strain compared to that obtained from a thermal effect.
Processing of Ti Alloys by Additive Manufacturing: A Comparison of the Microstructures Obtained by Laser Cladding, Selective Laser Melting and Electron Beam Melting
Authors: Reginster Sylvie , Mertens Anne , Paydas Hakan , Tchoufang Tchuindjang Jerome , Contrepois Quentin , Dormal Thierry , Lemaire Olivier , Lecomte-Beckers Jacqueline
Published: July 2013

In this study, samples of alloy Ti-6Al-4V have been processed by different additive manufacturing techniques in order to compare the resulting microstructure. In all three processes, ultrafast cooling gives rise to strongly out-of-equilibrium microstructures. However, the specific of the heat flow in each process lead to significant differences as far as the grains orientation and the resulting microstructural anisotropy are concerned.
Constituent Particles and Dispersoids in an Al-Mn-Fe-Si Alloy Studied in Three-Dimensions by Serial Sectioning
Authors: Dwyer Liam , Robson Joseph , da Fonseca Joao Quinta , Kamp Nicolas , Hashimoto Teruo , Thompson George E.
Published: July 2013

Second phase particles in wrought aluminium alloys are crucial in controlling recrystallization and texture. In Al-Mn-Fe-Si (3xxx) alloys, the size, spacing, and distribution of both large constituent particles and small dispersoids are manipulated by heat treatment to obtain the required final microstructure and texture for operations such as can-making. Understanding how these particles evolve as a function of process conditions is thus critical to optimize alloy performance. In this study, a novel 3-dimensional technique involving serial sectioning in the scanning electron microscope (SEM) has been used to analyse the intermetallic particles found in an as-cast and homogenized Al-Mn-Fe-Si alloy. This has allowed an accurate determination of the size and shape of the constituent particles and dispersoids derived from a 3-dimensional dataset. It is demonstrated that a proper consideration of the 3-dimensional microstructure reveals important features that are not obvious from 2-dimensional sections alone.
Microstructures and Mechanical Properties of a Novel Mg-Gd-Y-Zn-Zr Alloy
Authors: Yang Zhong , Li Jian Ping , Wang Yan Rong , Xiong Bi Wei
Published: July 2013

The microstructure characteristics and mechanical properties of as-cast and hot extruded Mg-5Gd-4Y-0.5Zn-0.5Zr (GWZ540) alloy were investigated. The results show that coarse the as-cast GWZ540 alloy consisted of α-Mg grain and two second phases, disc-like Mg5(Zn0.2Y0.2Gd0.6) and block-shaped Mg24(Y0.6Gd0.4)5. Hot extrusion resulted in a significant refinement of the α-Mg grains and a uniform distribution of the second phases, but with little effect on the composition and structure of the second phases. It is also shown that GWZ540 alloy exhibits higher UTS and TYS and elongation at both room and elevated temperature than those of WE54 alloy.
Reducing Mechanical Asymmetry in Wrought Magnesium Alloys
Authors: Robson Joseph
Published: July 2013

Many wrought magnesium alloys exhibit a characteristic asymmetry in mechanical properties when tested in compression and tension. In this paper, the fundamental origins of the asymmetry effect in wrought magnesium alloys are discussed and strategies to reduce asymmetry are presented. It is shown that both weakening the typical strong basal texture and introducing basal plate precipitates are predicted to reduce, but not eliminate, asymmetry in agreement with experiment. The implication of these results on the design of wrought magnesium alloys is discussed.
Crashworthiness of Magnesium Sheet Structures
Authors: Steglich Dirk , Bohlen Jan , Tian Xiao Wei , Riekehr Stefan , Kashaev Nikolai , Bargmann Swantje , Letzig Dietmar , Kainer Karl Ulrich , Huber Norbert
Published: July 2013

A hollow rectangular profile, as an example of a typical structural component made of magnesium alloy sheets has been built, tested and evaluated in order to assess its behaviour during axial crushing. The profiles were joined from plane sheets of AZ31 and ZE10, respectively, by laser beam welding and were then tested in compression. Numerical simulations have been conducted to understand the complex interplay between hardening characteristics of the materials under investigation, profile cross-section variation and energy absorption. The results from the compression testing of the profiles show that the welds are not the source of damage initiation and failure. The performance of the magnesium profiles in terms of dissipated specific energy is confirmed for small and intermediate displacements to be comparable to that of aluminium profiles. For large displacements, however, the shear-type failure mode of magnesium causes a sharp drop of the crushing force and thus limits the energy absorption. These findings demonstrate the requirement for an alloy and wrought magnesium process development specifically for crash applications which aims at progressive hardening along with high ductility for improving the bending and shear behaviour.
Corrosion of an Advanced Al-Cu-Li Alloy for Aerospace Applications
Authors: Carrick David M. , Hogg Simon C. , Wilcox Geoffrey D.
Published: July 2013

This paper discusses two Al-Cu alloys for aerospace applications, one which has a high concentration (>1.8 wt.%) of Li. These alloys are AA2024-T3 (Al-Cu) and AA2099-T8E77 (Al-Cu-Li) and are both in the plate format. Anodic polarisation and immersion in a 3.5 wt.% NaCl solution have been carried out and a comparison of the corrosion mechanisms have been made. Both alloys showed extensive corrosion over the surface, AA2024-T3, however, had areas of pitting that had joined together forming large corrosion regions, whereas AA2099-T8E77 had numerous corrosion pits that had not merged. The pits on AA2099-T8E77 propagated to a depth ~120 µm whereas on AA2024-T3 the maximum depth was ~85 µm. Intergranular and transgranular corrosion was also observed on the AA2024-T3 alloy following anodic polarisation. AA2099-T8E77 had reduced corrosion resistance with regards to Epit-Ecorr values. For both alloys, dissolution of matrix material surrounding the Cu-rich intermetallic particles was observed, highlighting the particles’ cathodic nature.
Consequences of Micro-Milled and Laser Structured Surfaces of CP-Titanium on Tension-Compression Fatigue Behaviour
Authors: Kühn Claudia , Kerscher Eberhard
Published: July 2013

Component surfaces can be modified by micro-structuring processes like micro-milling or laser structuring for functionality reasons. This modification induces small notches, whose dimensions are in the same order as the grain size. This could have an influence on the mechanical properties. This paper presents the results of tension-compression fatigue tests with structured and – for comparison – with unstructured micro-tensile specimens of cp-titanium grade 2. Longitudinal metallographic microsections illustrate the grain size of the microstructure and the geometry of the notches. The results of the fatigue tests show the influence of the notches on lifetime and endurance limit. With a Scanning Electron Microscope (SEM) the fracture surfaces, the crack initiation sites, and the crack propagation areas of all samples were analyzed. With these analyses we want to determine which notch structure dimensions relative to the grain size are tolerable.
Role of Electric Pulse Duty and Frequency on Properties of Micro-Arc Oxidized Titania Films Developed on Ti-6Al-4V
Authors: Venkateswarlu K. , Suresh S. , Rameshbabu N. , Sreekanth D. , Sandhyarani M.
Published: July 2013

The present work is mainly focussed on studying the effect of electric pulse frequency and duty cycle on the structural, morphological and corrosion characteristics of micro arc oxidation (MAO) films developed for a fixedoxidation timeof 2.5 min on Ti-6Al-4V biomedical implant material. For this purpose, the titania films are decisively developed under four different conditions arising from two levels of pulse duty cycle (10% and 75%) and frequencies (500 Hz and 1500 Hz). A phosphate based electrolyte system is employed for developing the titania films. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results demonstrated that though all the titania films are developed for the same oxidation time of 2.5 min, the rate of anatase to rutile phase transformation, the crystallite growth, the size and distribution of surface pores and film thickness of the titania film are strongly influenced by the electric pulse frequency and duty cycle. The potentiodynamic polarization (PDP) tests conducted under simulated body fluid (SBF) conditions (37 °C and 7.4 pH) showed that all the titania films could significantly improve the corrosion resistance of Ti-6Al-4V compared to that of the untreated alloy. Of all the titania films developed for the same oxidation time of 2.5 min, the one treated with 1500 Hz frequency and 75% duty cycle exhibited better corrosion resistance than those of the other films and the untreated Ti-6Al-4V implant material.
Novel Environmentally-Friendly Coatings for Aerospace Alloys
Authors: Harris Janette M. , Zhou Xiao Rong , Thompson George E. , Scott Phil , Zhang Xiao Yun , Shi Zhong Chuan , Sun Zhi Hua
Published: July 2013

In the present study, coatings of aluminium, zinc and combinations of aluminium-zinc and zinc-nickel were applied to steel substrates using the cold gas spray process. The effects of powder morphology and impact velocity, as determined by gas temperature and pressure, on the uniformity of the coatings were investigated. The through coating microstructure and composition were examined using scanning electron microscopy to determine the elemental distribution and the nature and extent of porosity. Work continues with an investigation of substrate condition and spray parameters on deformation and bonding. Significant plastic deformation of metal grains was evident. Further, it was revealed that the uniformity and compactness of the coatings are directly associated with the shape and size of the powders, and the gas pressure and temperature. The performance of the coatings is currently being evaluated and compared with ion vapour deposited and electrodeposited coatings.
Research on Microstructure and Tribological Properties of the Cp/AlSn Coatings Deposited by Magnetron Sputtering
Authors: Guo Qiao Qin , Li Jian Ping , Guo Yong Chun
Published: July 2013

The influences of microstructure and tribological properties of Cp/AlSn (Cp: carbon particule) composite films were applied to AlZn4.5Mg bearing alloy substrates using the closed-field unbalanced magnetron sputtering ion plating technique. The microstructure, phases and bond states of the coatings were separately characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The friction coefficients were measured using a pin-on-disc set-up. Results showed that the grain size and roughness of the films both decreased with increasing of carbon target current (IC) from 0.2 A to 0.8 A. Phases in the films were Al, Sn and C, although the films transformed from a crystalline state to amorphous when the carbon target current was applied. Al and Sn existed as pure metals. Carbon, composed of sp2and sp3bonds, mainly as sp2bonds, provided transfer films to reduce the friction coefficient of the films from 0.35 to 0.15. The specific wear ratio was a minimum, when the carbon target current was 0.4 A.
Microstructure and Mechanical Properties of Refilled Friction Stir Spot Welding of Commercial Pure Aluminium
Authors: Venukumar S. , Muthukumaran S. , Swaroop Y.
Published: July 2013

Aluminium and magnesium alloys are expected to make considerable contributions in reducing the weight of automobiles as they are increasingly used as an alternative to steel; improving fuel economy and vehicle performance while simultaneously reducing emissions. Higher electrical and thermal conductivities of these materials make them difficult to weld using existing resistance spot welding leading to high energy consumption. Friction stir spot welding has proven to be a better alternative to weld these materials. But a probe hole left behind is the main problem in conventional Friction Stir Spot welding (FSSW). In the present work a new method has been developed to refill the probe hole using an additional filler plate known as Refill Friction Stir Spot welding (RFSSW). This new refilling technique and the conventional FSSW process were both used to weld commercially pure aluminium lap shear specimens and the results were compared. The effect of tool rotational speed on mechanical and metallurgical properties were studied in both cases. Static shear strength of RFSSW weld samples was found to be better than conventional FSSW process at higher tool rotational speed. This is explained in terms of effective increase in cross sectional area of weld nugget due addition of more material from the filler plate thereby eliminating the probe hole.
Investigation of the Microstructure and Bio-Corrosion Behaviour of Mg-Zn and Mg-Zn-Ca Alloys
Authors: Lu Yu , Bradshaw Andrew , Chiu Yu Lung , Jones Ian
Published: July 2013

Biomedical applications of magnesium alloys have attracted increasing attention due to their unique combination of advantages. However, the poor corrosion resistance is an obstacle to magnesium alloys being used as biodegradable materials. As zinc (Zn) and calcium (Ca) are non-toxic and recognized as nutritionally essential elements in the human body, in this study Zn and Ca were selected as alloying elements to produce suitable bio-corrosion properties. The grain size was reduced significantly from 141.4 μm to 97.3 μm by adding Ca. The bio-corrosion performance of the two alloys (Mg-3Zn and Mg-3Zn-0.3Ca) was characterized using immersion tests in simulated body fluid at 37 °C. The alloys were dominated by pitting corrosion. Heat treatment was used to alter the microstructure and influence further the corrosion rate. The correlation between microstructure and bio-corrosion rate was evaluated, in the light of the alloying elements and the heat treatment employed.
Castable Aluminium Alloys for High Temperature Applications
Authors: Fan Yang Yang , Makhlouf Makhlouf M.
Published: July 2013

Most traditional aluminium casting alloys are based on the aluminium-silicon eutectic system because of its excellent casting characteristics. However, the solidus in this system does not exceed 577 °C and the major alloying elements used with silicon in these alloys have high diffusivity in aluminium. Therefore, while these elements enhance the room temperature strength of the alloy, they are not useful at elevated temperatures. Considering nickel-base superalloys, whose mechanical properties are retained up to temperatures that approach 75% of their melting point, it is conceivable that castable aluminium alloys can be developed on the same basis so that they are useful at temperatures approaching 300 °C. In this publication, we present the thought process behind developing a new castable aluminum alloy that is designed specifically for such high temperature applications and we present the alloy’s measured castability characteristics and its elevated temperature tensile properties.
Surface Roughness Minimization in Turning PEEK-CF30 Composites with TiN Cutting Tools Using Particle Swarm Optimization
Authors: Cabrera Francisco Mata , Garrido I. , Tejero J. , Gaitonde V.N. , Karnik S.R. , Davim J. Paulo
Published: July 2013

Poly ether ether ketone (PEEK) composite belongs to a group of high performance thermoplastic polymers and the addition of carbon fibers increases the resistance and rigidity of PEEK. Due to favorable mechanical and thermal properties and potential applications in various manufacturing industries, it is essential to analyze the machining performance of reinforced PEEK composites. The surface roughness is a widely used measure of product quality that could influence the performance of mechanical products and production costs. The present study establishes the relationships between the cutting conditions (cutting speed and feed rate) and three surface roughness parameters (centerline average surface roughness, maximum peak to valley height and root mean square roughness) by developing second order mathematical models based on response surface methodology (RSM). The reinforced PEEK with 30% of carbon fiber (PEEK-CF30) workpieces were machined using TiN-cutting tools. The experiments have been planned as per full factorial design of experiments (FFD). The developed surface roughness models were then employed with particle swarm optimization (PSO) to optimize the cutting conditions. PSO program gives the minimum values of surface roughness parameters and the corresponding optimal cutting conditions.
Cladding of Titanium and Magnesium Alloy by Explosive Welding Using Underwater Shockwave Technique and Effect on Interface
Authors: Habib M. Ahasan , Ruan Li Qun , Kimura Ryuji , Manikandan P. , Hokamoto Kazuyuki
Published: July 2013

The wide use of clad joints in practical application has been inhibited due to the difficulty in welding certain combinations such as tungsten/-copper, molybdenum/-copper and magnesium with aluminum, titanium and stainless steel. These material combinations are generally classified as difficult to weld by conventional material joining techniques due to the vast difference in material properties and the degradation of mechanical properties of the joints. Explosive welding is here a viable alternative technique. Explosive welding is a solid-phase welding process that uses the energy of a detonating explosive to create a strong metallurgical bond. This technique has achieved impressive success in the joining of metallurgically incompatible combinations that are otherwise impossible to join by conventional welding techniques. Though the technique is suitable for joining only thin plates, it is efficient in joining some difficult to join combinations like magnesium with aluminum, titanium and stainless steel. In this paper, the result of welding titanium and magnesium was reported.
Parallel Seam Welding of Aluminum Sheets by Magnetic Pulse Welding Method with Collision between Metal Jets
Authors: Aizawa Tomokatsu , Matsuzawa Kazuo , Okagawa Keigo , Ishibashi Masaki
Published: July 2013

This paper provides details about the adjacent parallel seam welding of a pair of aluminum sheets by a magnetic pulse welding (MPW) method. An impulse discharge current from a capacitor bank passes through a flat one-turn coil and concentrates on two parallel along the narrow middle parts of the coil. A magnetic flux is suddenly generated around the middle parts. This flux intersects the sheets which are overlapped on the middle parts. The resulting eddy currents are induced in the sheets, applying two parallel strong electromagnetic forces to them. The sheets having a gap collide with each other at high speed in two parallel. In this time, four metal jets occur just ahead of the collision front along the middle parts. Two metal jets occurring in the inside collide with each other if the experimental conditions are suitable.
Design of a High Current Transcranial Magnetic Stimulator for Flux-Concentration Type Electromagnetic Coil
Authors: Ueno Takahisa , Aihara Shigeru , Gotoh Yasuhiro
Published: July 2013

Transcranial Magnetic Stimulation (TMS) is a noninvasive method to cause depolarization or hyperpolarization in the neurons of the brain. The recent research has developed a novel magnetic coil that can generate higher magnetic field than a conventional coil and have converging capability, which would require a larger exciting current. In this research, a thyristor as a switching device was used for high current switching. The thyristor is a device of current drive. The current differences of each circuit in parallel connected thyristors were measured by changing gate voltage and gate rise time. The gate drive characteristic of parallel connected thyristors was also confirmed.
Hot Spots, High Explosives Ignition, and Material Microstructure
Authors: Horie Yasuyuki
Published: July 2013

This paper reviews the subject of high explosives ignition with focus on impact and shock loadings from the view point of modeling and identifying scientific issues that need to be addressed to establish a science basis on which to build a better predictive methodology for explosives safety. A motivation is to move explosives safety from empiricism to an advanced computation based analytic scientific and engineering basis, facilitating innovation. But because of the vastness of the subject, the scope of coverage is limited primarily to select aspects of shock and impact loadings that are relevant to the project the author has been involved in and presented in the companion paper by Min Zhou et al. of Georgia Institute of Technology.* (*Min Zhou et al., Materials Science Forum, in this volume)
Computational Simulation of Underwater Shock Wave Propagation Using Smoothed Particle Hydrodynamics
Authors: Shinzato Shuhei , Higa Yoshikazu , Tamaki Tatsuhiro , Iyama Hirofumi , Itoh Shigeru
Published: July 2013

Underwater shock wave phenomenon is applied to various fields such as manufacturing, food processing and medical equipment, and has been investigated with many experiment and numerical analysis. Because of low heat generation and possibility of downsizing of the device which generates shock wave, an application of shock wave induced by gap discharge in food processing has been studied recently. In this study, an ellipsoidal vessel filled with water is modeled in 2D and a computational simulation of underwater shock wave propagation is implemented using Smoothed Particle Hydrodynamics. Then, the computational result is compared with an experimental one and have a good agreement with the experimental one in qualitative. In the simulation, focusing of pressure wave, which is characteristic phenomenon of elliptical vessel, is observed.
Linaclotide: A New Option for the Treatment of Irritable Bowel syndrome with Constipation and Chronic Idiopathic Constipation in Adults
Authors: Parker Colleen H. , Yuan Yuhong , Liu Louis Wing Cheong
Published: July 2013

Chronic idiopathic constipation (CC) and irritable bowel syndrome with predominant constipation (IBS-C) are the 2 most common conditions among functional gastrointestinal disorders. Despite current multiple therapeutic options, treatment remains challenging and dissatisfactory to many patients. Linaclotide is a novel therapeutic agent, which is a guanylate cyclase receptor agonist that stimulates water secretion from the intestinal epithelium by promoting chloride and bicarbonate efflux into the lumen through activation of the cystic fibrosis transmembrane conductance regulator. Clinical trials have demonstrated that linaclotide is effective, safe and well tolerated in patients with CC and IBS-C. This review article highlights the mechanism of action of linaclotide, reviews published literature based on a search of databases, including MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL), up to February 2013, and compares its utility with other currently available agents.
Minimal Generators of the Defining Ideal of the Rees Algebra Associated with a Rational Plane Parametrization with μ = 2
Authors: Cortadellas Benítez Teresa , D'Andrea Carlos
Published: July 2013

We exhibit a set of minimal generators of the defining ideal of the Rees Algebra associated with the ideal of three bivariate homogeneous polynomials parametrizing a proper rational curve in projective plane, having a minimal syzygy of degree 2.
The hyperspaces Cn(X) for finite ray-graphs
Authors: Esty Norah
Published: July 2013

In this paper we consider the hyperspace Cn(X) of non-empty and closed subsets of a base space X with up to n connected components. The class of base spaces we consider we call finite ray-graphs, and are a noncompact variation on finite graphs. We prove two results about the structure of these hyperspaces under different topologies (Hausdorff metric topology and Vietoris topology).
Seasonal variability and long-term evolution of tropospheric composition in the tropics and Southern Hemisphere
Authors: Wai K. M. , Wu S.
Published: July 2013

Abstract. Present-day and future impacts of biomass burning and other sources in the tropics and Southern Hemisphere are studied by global chemical transport model (GCTM), satellites retrievals and surface measurements. The spring CO peaks found at Mahe Island (Western Indian Ocean) are attributed to the burnings in India but not those from Northern Africa. Easter Island (Eastern Pacific Ocean) is impacted indirectly by the hemispheric zonal transport of CO due to the burnings in Southern Africa/Latin America, via the westerlies. An increasing trend for CO by 0.33 ppb yr-1 in the past decade at Ascension Island is attributed to the combined effects of Latin American/Southern Africa burnings and increase of CH4 level. Changes in water vapour and UV over Southern Atlantic Ocean (SAO) in future January have dominated effects on the O3 distribution. More than 55% of O3 concentrations over SAO in both present-day and future September are not directly affected by the emissions (including lightning) over the adjacent two continents but attributable to transport of O3 from outside due to CO and CH4 oxidation and stratospheric intrusion. High NOx emissions in both continents in future increase the PAN concentrations over remote oceans at higher southern latitudes (> 35° S) as far as those near Australia, affecting the O3 budget over there. Future changes of biomass burning and anthropogenic NOx emissions in Southern Africa lead to a new area of O3 maximum near South Africa. The resulted O3 outflow to the Indian Ocean is pronounced due to the effects of the persistent anti-cyclone. A general reduction of future OH radical concentrations is predicted over the remote marine boundary layer in the tropics and Southern Hemisphere, due to the increases in CH4 and CO emissions combined with the low-NOx environment.
Liquid–liquid phase separation in particles containing organics mixed with ammonium sulfate, ammonium bisulfate, ammonium nitrate or sodium chloride
Authors: You Y. , Renbaum-Wolff L. , Bertram A. K.
Published: July 2013

Abstract. As the relative humidity varies from high to low values in the atmosphere, particles containing organics and inorganic salts may undergo liquid–liquid phase separation. The majority of the laboratory work on this subject has used ammonium sulfate as the inorganic salt. In the following we studied liquid–liquid phase separation in particles containing organics mixed with the following salts: ammonium sulfate, ammonium bisulfate, ammonium nitrate and sodium chloride. In each experiment one organic was mixed with one inorganic salt and the liquid–liquid phase separation relative humidity (SRH) was determined. Since we studied 23 different organics mixed with four different salts, a total of 92 different particle types were investigated. Out of the 92 types, 49 underwent liquid–liquid phase separation. For all the inorganic salts, liquid–liquid phase separation was never observed when the oxygen-to-carbon elemental ratio (O:C) was ≥ 0.8 and was always observed for O:C<0.5. For 0.5 ≤ O:C< 0.8, the results depended on the salt type. Out of the 23 organics investigated, the SRH of 20 organics followed the trend: (NH4)2SO4 ≥ NH4HSO4 ≥ NaCl ≥ NH4NO3. This trend is consistent with previous salting-out studies and the Hofmeister series. Based on the range of O:C values found in the atmosphere and the current results, liquid–liquid phase separation is likely a frequent occurrence in both marine and non-marine environments.
Feasibility of polarized all-sky imaging for aerosol characterization
Authors: Kreuter A. , Blumthaler M.
Published: July 2013

Abstract. In this study, we investigate the method of polarized all-sky imaging with respect to aerosol characterization. As a technical frame work for image processing and analysis, we propose Zernike polynomials to decompose the relative Stokes parameter distributions. This defines a suitable and efficient feature vector which is also appealing because it is independent of calibration, circumvents overexposure problems and is robust against pixel noise. We model the polarized radiances of realistic aerosol scenarios and construct the feature vector space of the key aerosol types in terms of the first two principal components describing the maximal variances. We show that, using this representation, aerosol types can be clearly distinguished with respect to fine and coarse mode dominated size distribution and index of refraction. We further investigate the individual influences of varying aerosol properties and solar zenith angle. This suggests that polarized all-sky imaging may improve aerosol characterization in combination with sky scanning radiometers of the existing Aerosol Robotic Network (AERONET) especially at low aerosol optical depths and low solar zenith angles.
Black shale deposition during Toarcian super-greenhouse driven by sea level
Authors: Hermoso M. , Minoletti F. , Pellenard P.
Published: July 2013

Abstract. One of the most elusive aspects of the Toarcian Oceanic Anoxic Event (T-OAE) is the paradox between carbon isotopes that indicate intense global primary productivity and organic carbon burial at a global scale, and the delayed expression of anoxia in Europe. During the earliest Toarcian, no black shales were deposited in the European epicontinental seaways, and most organic carbon enrichment of the sediments postdated the T-OAE (defined by the overarching positive trend in the carbon isotopes). In the present studied, we have attempted to establish a sequence stratigraphy framework for Early Toarcian deposits recovered from a core drilled in the Paris Basin using a combination of mineralogical (quartz and clay relative abundance) and geochemical (Si, Zr, Ti and Al) measurements. Combined with the evolution in redox sensitive elements (Fe, V and Mo), the data suggest that expression of anoxia was hampered in European epicontinental seas during most of the T-OAE due to insufficient water depth that prevented stratification of the water column. Only the first stratigraphic occurrence of black shales in Europe corresponds to the "global" event. This interval is characterised by > 10% Total Organic Carbon (TOC) content that contains relatively low concentration of molybdenum compared to subsequent black shale horizons. Additionally, this first black shale occurrence is coeval with the record of the major negative Carbon Isotope Excursion (CIE), likely corresponding to a period of transient greenhouse intensification likely due to massive injection of carbon into the Atmosphere–Ocean system. As a response to enhanced weathering and riverine run-off, increased fresh water supply to the basin may have promoted the development of full anoxic conditions through haline stratification of the water column. In contrast, post T-OAE black shales were restricted to epicontinental seas (higher Mo to TOC ratios) during a period of relative high sea level, and carbon isotopes returning to pre-T-OAE values. Comparing palaeoredox proxies with the inferred sequence stratigraphy for Sancerre suggests that episodes of short-term organic carbon enrichment were primarily driven by third-order sea level changes. These black shales exhibit remarkably well-expressed higher-frequency cyclicities in the concentration of redox-sensitive elements such as iron or vanadium whose nature has still to be determined through cyclostratigraphic analysis.
3D DIGITIZATION AND MAPPING OF HERITAGE MONUMENTS AND COMPARISON WITH HISTORICAL DRAWINGS
Authors: Fiorillo F. , Remondino F. , Barba S. , Santoriello A. , De Vita C. B. , Casellato A.
Published: July 2013

Abstract. The paper presents the integration of different 3D recording techniques and instruments to survey the archaeological area of Paestum (Italy). Paestum was included in the UNESCO World Heritage list since 1998, and still preserves the ruins of Greek and Roman times. Photogrammetry and terrestrial laser scanning (TLS) acquisitions were integrated in order to exploit the advantages of the 3D surveying techniques and produce digital models, orthoimages, maps and other geometric representations useful for archaeological, architectural and cultural touristic purposes. The obtained 3D results are then compared to historical representations to show the high quality of such ancient manual drawings.
3D SURVEY OF PRE-HISPANIC WALL PAINTING WITH HIGH RESOLUTION PHOTOGRAMMETRY
Authors: Lucet G.
Published: July 2013

Abstract. The survey and representation of pre-hispanic wall painting use to be done with traditional photography, we describe the difficulties and limitations found in this approach and we show another solution to improve the quality of this documentation. It relies on the use of photogrammetry and MicMac program. The calculated orthophotos have an accurate geometry, they are high resolution and the three-dimensional models present a high level of detail. We obtain a complete representation which satisfy the requirements of art historians and conservators to study the meanings of the paintings and their conservation state. Furthermore, as this improvement is achieved by following a particular strategy for the photo sessions and the mathematical processing on the images, it doesn't need the acquisition of additional equipment. We explain how we applied the method in the registration of a structure covered with pictorial representations that was discovered in the archaeological site of Las Higueras, México.
EXPERIMENTS WITH METADATA-DERIVED INITIAL VALUES AND LINESEARCH BUNDLE ADJUSTMENT IN ARCHITECTURAL PHOTOGRAMMETRY
Authors: Börlin N. , Grussenmeyer P.
Published: July 2013

Abstract. According to the Waldhäusl and Ogleby (1994) "3 x 3 rules", a well-designed close-range architectural photogrammetric project should include a sketch of the project site with the approximate position and viewing direction of each image. This orientation metadata is important to determine which part of the object each image covers. In principle, the metadata could be used as initial values for the camera external orientation (EO) parameters. However, this has rarely been used, partly due to convergence problem for the bundle adjustment procedure. In this paper we present a photogrammetric reconstruction pipeline based on classical methods and investigate if and how the linesearch bundle algorithm of Börlin et al. (2004) and/or metadata can be used to aid the reconstruction process in architectural photogrammetry when the classical methods fail. The primary initial values for the bundle are calculated by the five-point algorithm by Nistér (Stewénius et al., 2006). Should the bundle fail, initial values derived from metadata are calculated and used for a second bundle attempt. The pipeline was evaluated on an image set of the INSA building in Strasbourg. The data set includes mixed convex and non-convex subnetworks and a combination of manual and automatic measurements. The results show that, in general, the classical bundle algorithm with five-point initial values worked well. However, in cases where it did fail, linesearch bundle and/or metadata initial values did help. The presented approach is interesting for solving EO problems when the automatic orientation processes fail as well as to simplify keeping a link between the metadata containing the plan of how the project should have become and the actual reconstructed network as it turned out to be.