bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Characteristics Study of Belt Conveyor Based on Virtual Prototyping
Authors: Zhou Guang Lin , Hao Shuang Shuang
Published: August 2009

With the improvement of the load and speed of belt conveyor, the dynamic characteristic problem of belt conveyer appears especially outstanding. This paper analyzed the force situation of the conveyer by the discrete dynamics model, divided n viscoelastic properties mass units in advance, then built system analysis dynamics model by vibration mechanics, built modal neutral file of the flexible belt block by means of finite element analysis software, and built the virtual prototype model of the belt conveyor using ADMAS program. It analyzed the effect of stiffness and damping of belt on the starting process by dynamic characteristics simulation method. The simulation results showed that the speed wave period of belt with the smaller stiffness was longer and the peak was bigger, the belt speed easily occurred stronger surge, the transverse vibration of belt conveyor became more violent. With the increasing of stiffness, the belt speed wave peak value decreased. As the same time, the speed surge also decreased when other operation parameters of the belt conveyer system are fixed, with increasing of the damping, the dynamic tension force peak became smaller gradually, it led to decrease of vibration curve peak. Damping coefficient played the important role in decreasing the vibration intensity, the research result offers a new basis for the analysis and study of the dynamic characteristics of belt conveyor.
Comparison of Stretching with Horizontal V-Shaped Anvils and Common Flat Anvils
Authors: Xiao Shi Cheng , Zhang L.P. , Ni Li Yong , Yang Wen Hua , Liu H.L.
Published: August 2009

Research was conducted for stretching with horizontal V-shaped anvils (HVA) and common flat anvils (FA). The forgoing research gave the simulation results of single blowing during stretching, and did not pay attention to the influence of the deformation, resulting from the previous blowing, upon the next blowing. ANSYS software is adopted to simulate the through-continuous blowing of HVA and FA forging methods. The transversal stress distribution along the horizontal central axis on the crosssection of the stretched forging is analyzed. The simulation results show that during the stretching with flat anvils, when the ratio of the flat anvil width to the billet height is 1.0 and the ratio of the billet width to the billet height is 0.5, the transversal stress is tensile all the time, and increases as the stretching goes. On the contrary, during the HVA stretching, the stress is compressive and its absolute value increases gradually. The results show that the HVA stretching method is prior to the FA stretching method in the controlling of transversal stress. Conducted physical experiment verified the results.
Investigation on the Formability of a Tube in Pulsating Hydroforming
Authors: Yang Lian Fa , Chen Feng Jun
Published: August 2009

Based on the finite element simulation of tube-hydroforming process with pulsating internal pressure, the influence of the pressure increment p and the time increment t of the pulsating pressure upon the formability of a tube have been investigated by analyzing and comparing the four formability indicators such as thickness distribution, die-filling ability, wall thickness uniformity and potential fracturing. A new indicator f is proposed to estimate the formability of a tube on the basis of the finite element analysis (FEA). The results show that: the indicator f can reasonably reflect the combination formability of a tube in hydroforming including the die-filling ability, the wall-thickness uniformity and the deformation reliability; the p and t values have different influence on the four formability indicators as mentioned above; the smaller the p and t values or the more the internal pressure pulsates during the forming process, the better the combination formability of the tube would be.
3D FE Modeling Simulation of Cold Rotary Forging with Double Symmetry Rolls
Authors: Han Xing Hui , Hua Lin , Zhao Yumin
Published: August 2009

A novel metal plastic forming technology, cold rotary forging with double symmetry rolls, is presented on the basis of cold rotary forging with single roll. A reasonable 3D elastic-plastic dynamic explicit FE model of cold rotary forging with double symmetry rolls is developed under the ABAQUS software environment. Through simulation, the distributions and histories of different field-variables such as stress, strain and force and power parameters are investigated in detail. The research results not only provide an advanced and innovative technology for metal plastic forming, but also help to better understand cold rotary forging with double symmetry rolls.
Study on After-Forging Austenite Recrystallization Rule of Low-Pressure Rotor Steel 26Cr2Ni4MoV with Thermo-Torsion Method
Authors: Ni Li Yong , Kang Peng Chao , Liu Zhu Bai , Yang Wen Hua
Published: August 2009

In order to investigate the nucleation and growth of after-forging static recrystallization of low-pressure rotor steel 26Cr2Ni4MoV, the thermo-torsion experiment was conducted at 900°C,1000°C and 1100°C, respectively. The outer deformation of the used specimens was 0.21. The specimens were kept under a certain temperature for different periods. Results show that the recrystallization grain grew slowly at 900°C and the grain size became even after 30 minutes. The sizes of most grains were almost constant and only several grains grew bigger after 60 minutes. When the specimens were kept at 1000°C and 1100°C for one minute, static recrystallization was completed and the grain size was even. The said research could provide theoretical base for the controlled forging and after-forging heat treatment.
Numerical Simulation and Experiment of Self-Piercing Riveting with Solid Rivet Joining Multi-Layer Aluminum Sheets
Authors: Huang Zhi Chao , Yao Qiu Hua , Jiang Ning , Zhou Ze Jie
Published: August 2009

Numerical simulation and experiment of self-piercing riveting with solid rivet joining multi-layer aluminum sheets are carried out in this paper. The forming process of the riveting and the distribution of stress are analyzed, the results show that the simulation is consistent with the experiment. The results of experiment prove that the transition point of the cone-shaped head of the solid rivet, the size and position of groove affect directly the quality of riveting. The fillet at the transition point of the cone-shaped head of the solid rivet can decline the maximum stress of the rivet. When the distance between the center of groove and bottom of rivet is about three quarters of the bottom sheet thickness, the bottom sheet of self-piercing does not fall off. The self-piercing riveting with solid rivet joining multi-layer aluminum sheets is feasible.
Mechanical Properties of the Natural Heterogeneous Composites
Authors: Lin Ai Guang , Ding Xiao Fei , Xie Z.D. , Sun Bao Yuan
Published: August 2009

According to the results of mechanical property tests, the mechanical properties of heterogeneous composite-Patinopecten yessoensis (scallop) shells are anisotropic and related closely to the microstructure. The results of compression and three-point bending tests indicated that the compressive strength which vertical load on the shell surface was approximately 3.8 times than the parallel case. The bending strength which applied to the external of the shell was about 2.2 times than it loaded from the inner surface. Patinopecten yessoensis (scallop) shell is organic-inorganic composite and has different microstructure in different location in according to its functional requirements. Patinopecten yessoensis (scallop) shell is typical bioactive functional gradient material, and its microstructure is worthy of heterogeneous composite material parts design.
Research on the Stress Intensity Factor of the Crack Normal to and Dwelling on the Interface of the Cermet Cladding Part
Authors: Yang Jun Ru , Li Zhao Qian , Huang Chuan Zhen , Ren L.X. , Jia Q.H.
Published: August 2009

Basing on the theoretical study on the stress intensity factor (SIF) of the crack normal to and dwelling on the interface of the cermet cladding part, the finite element analysis (FEA) of the crack SIF is made. The change laws of the SIF with the load action angle, the load Q, the clad thickness ratio h1/h and the elastic modulus ratio E1/E2 are obtained. The research results have theoretical and steering significance on the wide application of the cermet cladding part.
Preparation of Ni-Al Intermetallics Bonded TiC Porous Cermets by SHS Method
Authors: Huang Shao Yun , He Bo Lin , Shi Jian Ping
Published: August 2009

Porous cermets composites were prepared from mixed powders (Ni, Al, Ti and C) by SHS (Self-propagating High-temperature Synthesis) method. When Ni-Al intermetallics bonded TiC porous cermets substitute for TiC ceramic as perform in the process of manufacturing Ni-Al/TiC composites by pressureless melt infiltration, the wetting of the ceramic material and Ni-Al intermetallics can be improved. In this study, the microstructure and mechanical properties (density and compressive resistance strength) were reported. It is learnt from the study that the relation between the open porosity and the pore size does not exist, the former depends on the green density, and the latter depends on the particle size of the nickel powder. The porous cermets with porosity ranging from 40% to 50%, pore size from 1μm to 300μm, and the compressive resistance strength about 15 MPa can be prepared by SHS. SEM observations of fracture surface suggest the fracture mode is brittleness fracture, and the microstructures of the porous cermets are very homogenous.
Surface Modification of High Chrome Steel by Laser Surface Melting
Authors: Li M.Y. , Wang Yong , Zhao W.M. , Han Bin , Cheng Yi Yuan , Li Chao Wen
Published: August 2009

Laser surface melting has been performed on high chrome steels by a 5kW CW CO2 laser using different overlapping ratios. The microstructures of laser melted steels were analysed by SEM and the hardness profiles were determined by a Vickers hardness tester. The corrosion characteristics of laser melted steels in 3.5% NaCl solution were studied by electrochemical corrosion equipment. The melted zone of a single laser track exhibits a mixed structure of dendritic, cellular and equiaxed austenite while the overlapped melted zone is only composed of austenitic dendrites. Using a large overlapping ratio (OR) gives a more uniform hardened-depth. The microhardness with an OR of 33.3% is higher compared to 16.7% and 50%. The corrosion resistance of laser melted steel is improved arising from the dissolution of carbides, the increasing of alloying elements in the solid solution and the large amount of austenite. Among all the studied specimens the one, which is laser treated with 33.3% OR presents the better corrosion resistance.
Promotion of Adhesive and Wear Performances of Chromium Coating with Plasma Non-Transferred Arc Treatment
Authors: Huang Jie Wen , Xiong Dang Sheng , Fan Xin Min
Published: August 2009

Plasma arc, a kind of high energy density beam, is proposed as one kind of surface treatments in this paper to improve the adhesive properties of the chromium coatings to the steel substrate. Scratch tests are used to obtain the critical load (Lc) of the coatings. The wear behaviors are evaluated by a reciprocating ball-on-flat wear machine and the wear tracks of the coating were characterized by scanning electronic microscope (SEM). Results show that plasma arc treatment could promote the adhesive and the wear performances of the chromium coatings. Optimal value of Lc and the wear resistance of the treated coatings could be obtained when the average output energy density of the plasma arc (E) grow to 1.05×105J/m2. The comparative study indicates that the promotion of the adhesion could be attributed to the formation of the inter-diffused alloyed layer and the improved hardness distribution. This promotion then contributes to the improvement of the wear performance, which makes up, even exceeds the loss of it caused by the drop of the coatings hardness.
Investigation of Metal Droplet Flattening Behavior after Impacting onto Stainless Steel Substrate
Authors: Zeng Hao Ping , Zhu Liang Rong , Gao Y.Q. , Xu Wen Ji , Yang L. , Liu Chang Sheng
Published: August 2009

During plasma spray forming, the forming quality is directly influenced by the flattening behavior of the droplet impacted onto the substrate, which is determined by the flattening configuration and solidification state of the droplet. In this study, according to the rule of Reynolds number and Peclet number, the flattening behavior of big-size molten droplet impacted onto the substrate with low-speed were experimentally simulated during flattening. The droplets of Sn30Pb70, Zn and ZA12 impacting onto the stainless steel substrate with different velocity were investigated. Splashing degree was introduced to evaluate the flattening profiles of the splats. The relationships between the splashing degree and the impact velocity, Reynolds number and Weber number of the droplet were established. Experimental results show that the flattening and diffusion are impeded by the dynamic viscosity and surface tension of the droplets, and the impeding effects are more remarkable when the impact velocity is lower. The research has a significant ap
Study on the Composite Technology of Electro-Brush Plating and Arc Spraying
Authors: Zhao Zhi Yu , Xu Wen Ji , Zhang Su Zhi
Published: August 2009

Zinc-alloy with low melting point can be easily sprayed directly on the production surface to fabricate a mould with high precision by arc spraying. But the zinc-alloy mould has the disadvantage of easy invalidation due to its relatively low hardness and poor anti-wear property. In this paper, the surface modification of zinc-alloy tooling by composite electro-brush plating was researched. The joining mechanism between the plating film and sprayed coating was investigated, and the law of quality control on the unification of rapid tooling and surface modification was revealed. A new modification technology possessing the advantage of economical and high quality surface relating to moulding was developed with independent intellectual property right.
The Effect of QPQ Salt-Bath Nitriding on Microstructure and Wear Resistance of 3Cr2W8V Steel
Authors: He Bo Lin , Yu Ying Xia , Shi Jian Ping
Published: August 2009

The wear resistance, corrosion resistance and hardness can be greatly increased by using low temperature QPQ salt-bath nitriding treatment. And it is a new strengthening method without distortion in the treating process. In this paper, 3Cr2W8V steel is dealt with QPQ salt-bath nitriding at 520°C, 540°C, 560°C and 2h, 4h, 6h, respectively. The treated surface microstructure was analyzed by using SEM. The depth of nitriding layer, scratch hardness and wear-resistance were tested for both QPQ salt-bath treated and untreated specimen. The corrosion resistance was tested in the 5%NaCl water by using spraying method. The experimental results indicate that a certain depth of white layer and diffusion layer of the steel can be obtained by using low temperature QPQ salt-bath nitriding treatment. The nitriding compound layer with high hardness, superior wear-resistance and stable microstructure can also be obtained on the surface of the parts. With increasing the temperature and the nitriding time, the depth of nitriding layer, scratch hardness and wear-resistance of 3Cr2W8V steel were greatly increased. Comparing with the untreated specimen, its hardness enhances 95.0%, wear resistance enhances 212.3%, anti-corrosion enhances 1288.9%. The experimental results show that the low temperature QPQ salt-bath nitriding treatment has many advantages, such as fast nitriding speed, uniform heating, short process time, low treating temperature, small distortion, high production rate, low cost, stable nitriding quality without pollution and so on.
Effect of Arc Current Ultrasonic-Frequency Pulsation on Plasma Cut Quality
Authors: Wang Jia You , Yu J.H. , He C.H. , Yang F.
Published: August 2009

The present work proposes a novel plasma cutting system using the ultrasonic frequency pulsed arc, and then experimentally investigates the effect of pulse process parameters on cut quality in the frequencies of 20-60 kHz. It is shown that kerf widths, bevel angle, straightness and dross attached level decrease obviously with the appropriate increases in the frequency and amplitude of pulse current. Furthermore, cutting heat affected zone narrows and cut hardness drops clearly in the pulsed cutting. This current pulsation can thus improve plasma cut quality remarkably, and finally leads to a narrower, flatter and more perpendicular cut of better remachinability. Experimental results simultaneously demonstrate that the effectiveness of the ultrasonic-frequency pulsed cutting process developed at the low current of arc.
Investigations of the High Vacuum Die Castings of Dumbbell Specimens
Authors: Jou Rong Yuan
Published: August 2009

Compare to atmosphere die casting or moderate vacuum die casting process, use of the high vacuum die casting can enhance excluding gas volumes in the mold, improve the casting mechanical properties and density, and increase the fabrication feasibility for casting small feature size, shape, and higher quality of product. The process of high vacuum die casting for dumbbell specimens is established and implemented for evaluation of this innovative manufacturing technology. A transparent acrylic mold is fabricated to investigate the vacuum injection for vacuum die casting process and a metal mold is fabricated to test the real manufacturing of high vacuum die casting. To visualize the flowing pattern inside the mold under the consequence of evacuation processing, flow visualization experiments are conducted. Then, the specimen is molded by the high vacuum die casting process and the specimen castings are test by a universal testing machine for its loading-elongation relationship. The porosities of specimen casting are examined by scale weighting and direct visual inspection ways. Experimental results show that the high vacuum die casting process is effective to reduce the porosity (5.47% increment in weight) and to increase the strength (4.83% increment in maximum stress) of the investigated specimen. An obviously vortex roll is established along the centerline position of dumbbell specimen which may be became the source of porosity in real processing. Meanwhile, an excellent vacuum sealing is critical to the success of high vacuum die casting.
Dynamic Simulation of Hydro-Mechanical Differential Turning Hydraulic System of Tracked Vehicle
Authors: Zhou Zhi Li , Cao F.Y. , Xu L.Y.
Published: August 2009

Being an important subsystem of hydro-mechanical differential turning system of tracked vehicle, the turning hydraulic system plays the crucial role on turning and running performance of tracked vehicle. The mathematical model and simulated model of turning hydraulic system are established. The dynamic performance of different running parameters and structural parameters of certain tracked vehicle is simulated and analyzed adopting Runge-Kutta four, five step arithmetic in this paper. The theory basis of system optimization design, parameters match and performance analysis of hydro-mechanical differential turning system is provided.
Analysis of Internal State Performances of the Electric Spindle Bearings Running at an Extreme Ultra-High-Speed
Authors: Li Song Sheng , Zuo T.T. , Hu Z.H. , Mao H.W. , Chen P. , Chen Xiao Yang , Gu Jia Ming
Published: August 2009

Aiming at the problem of analyzing for the dynamic performances of the spindle bearings running at an extreme ultra-high-speed in high-speed electric spindles, a model is built by taking the inertia effects and EHL at the extreme ultra-high-speed into account. Based on the system simulation about a bearing on the movements of every ball, the contact areas states and the lubrication states between balls and both ring raceways, the thermal state inside the bearing and so on, the internal state performances such as the movements and the inertia forces of all the balls, the contact forces and the lubrication films and the temperatures in the contact areas between balls and both ring raceways are analyzed in some different working conditions and configurations. The simulation results showed that the main factors affecting the state performances of a bearing running at an extreme ultra-high-speed are the inertia effects of the balls and the overheating in the contact areas between the balls and both ring raceways, which indicates that it can be improved by adopting the ball material with smaller mass density and the structure with a smaller ball diameter and more ball elements.
Efficiency-Reinforcement Design of Hydraulic Reciprocating Sealing Element Driven by TRIZ Technology Evolution
Authors: Zhang Fu Ying , Lu Xi Mei , Wang Ping , He Qing Ping
Published: August 2009

The efficiency reinforcement technologies of sealing is important for improving sealing’s reliability and effectivity which result in zero leakage. Technology evolution of TRIZ can be used to forecast the future technology in products. These future technologies can guide a designer along the right direction of developing a new product. In this paper, the efficiency-reinforcement principle of hydrodynamic reciprocating sealing is discussed, technology evolution of TRIZ is integrated with the efficiency reinforcement design of hydrodynamic reciprocating sealing element to predict its future structure state. A new cross section shape of reciprocating sealing element corresponding to the predicted structure state is presented. The computational model of the new reciprocating seal element is established with ANSYS, and its stress, strain and pressure distribution are also analyzed. The results demonstrated that the presented seal elemente outperforms the old O-ring seal in efficiency reinforcement capacity.
Coordination Action: NMP3-CA-2008-218331-NaPolyNet Setting up Research-Intensive Clusters across the EU on Characterization of Polymer Nanostructures
Authors: Silvestre Clara
Published: September 2009

NaPolyNet is a 36 month project involving 15 partners from 10 European countries. The objectives are: 1) to network at regional, national and international level with experts on the characterization of polymer nanostructured materials in the field of packaging, textiles and membranes, bridging the gap between scientific and engineering approaches for the improved understanding of the structure-performance correlation in polymer devices; 2) to facilitate transnational access to important and unique equipment and to train young scientists and SMEs technologists; 3) to harmonize the work necessary for new standards in the field of characterization of polymer nanostructures for packaging, textiles and membranes. NaPolyNet will also focus on latest findings for managing the safety implications of polymer nanostructure along the life-cycle of those products.
The activities are grouped into 7 work-packages (WP). After setting up the procedures for managing the project, the team will map the competences in the different field of characterization of polymer nanostructures and will set up an European Open Laboratory (EOL) open to outside the consortium partners incorporating the best and novel characterization methodologies and expertises.
The EOL will allow average trained users of equipment for thermal, structural, morphological, mechanical characterization to produce reliable data on nanostructured materials and correctly interpret them. An international Workshop is planned on processing-structure-dynamics-and-properties of polymer nanostructures in order to further support development and design of intrinsically safe nanomaterials. The last part of the project will be dedicated to harmonize the work for preparation of new standards for polymeric nanomaterials characterization and to overcome barriers to the industrial application of polymer nanostructured materials especially in SMEs.
Starch Based Biodegradable Nanocomposites: Structure and Properties
Authors: Ivanova Tatjana , Lilichenko Nadezda , Zicans Janis , Maksimov Robert D.
Published: September 2009

Plasticized starch (PS)/montmorillonite clay (MMT) nanocomposites were prepared by casting technique. Structural features, stress-strain characteristics and sorption properties were investigated. Upon introduction of rather small amounts of MMT, the PS parameters of the mechanical and barrier properties considerably improve. Tensile strength and elastic modulus of the materials examined decrease with increased moisture content, but the effect of reinforcement of PS with MMT nanoparticles remain intact.
Effect of Heat Treatment on Ti(C,N)-SiC-Si3N4-C Ceramic Nanocomposites
Authors: Biedunkiewicz Anna , Gabriel U. , Figiel P.
Published: September 2009

The paper presents results of an analysis conducted over heating of nc-Ti-Si-C-N/C powder in argon atmosphere. TG-DSC-MS measurements were carried out under non-isothermal and isothermal conditions. The samples were heated up in series to 1573, 1673 and 1773 K. Four stages of the process were distinguished. In the first, endothermic stage, evolution of volatile products contained in raw samples took place. In the second, exothermic stage, oxidation of nc-Ti-Si-C-N/C contained in raw samples occured by the oxygen present in argon at a trace level. At the third stage pyrolysis of organic compounds, present in the samples, and carbonization of nc-Ti-Si-C-N/C, and in the fourth stage oxidation of purified composite by oxygen occurring in argon proceeded. Kinetic description of the process was presented at the example of series heated up to 1773 K. Coats-Redfern equation was applied. The kinetic models (forms of g(α) function) and Arrhenius parameters A and E were determined for the stages. An analysis of the process was performed using the obtained kinetic data.
Electric Field Driven Magnetic Domain Wall Motion in Iron Garnet Films
Authors: Logginov A. , Meshkov G. , Nikolaev A. , Nikolaeva E. , Pyatakov A. , Zvezdin A.K.
Published: September 2009

The room temperature magnetoelectric effect was observed in epitaxial iron garnet films that appeared as magnetic domain wall motion induced by electric field. The films grown on gadolinium-gallium garnet substrates with various crystallographic orientations were examined. The effect was observed in (210) and (110) films and was not observed in (111) films. Dynamic observation of the domain wall motion in 800 kV/cm electric field pulses gave the domain wall velocity in the range 30÷50 m/s. Similar velocity was achieved in magnetic field pulse about 50 Oe.
The Effect of Disordering on Magnetic Properties of Fe-Al Alloys
Authors: Voronina E. , Yelsukov Eugene P. , Korolyov A. , Nagamatsu S. , Fujikawa T. , Miyanaga T.
Published: September 2009

The results of magnetometric, Mössbauer and XMCD (X-ray Magnetic Circular Dichroism) studies of B2 or DO3–type ordered (25 to 35 at.%Al) and disordered by mechanical activation (35 to 60 at.% Al) Fe-Al alloys are considered. For the description of magnetic characteristics of the studied alloys the validity of local magnetic moments models is discussed. The models suppose that Fe atom local magnetic moments are collinear with magnitude and direction depending on the number of Al atoms in the Fe nearest neighbourhood.
Investigation of Magnetorheological Suspensions by Optical Methods
Authors: Nikitin L.V. , Kudryavcev D.N. , Shashkov I.V. , Kazakov A.P.
Published: September 2009

In this work we studied magnetorheological suspensions, which are produced by dispersion of magnetic particles in liquid polymer matrix, based on natural and synthetic rubber. Such suspensions are the raw materials for creation of new high-elastic magneto-controlled composite materials (magnitoelastics[1-4]). Processes of aggregation and structurization of magnetic particles in suspension are also examined. We discovered that motion of magnetic clusters in oligomer solution has interrupted character. Such behavior can be explained by interaction of magnetic clusters moving in not uniform magnetic field with polymer net fragments. Evaluation of polymer net’s elastic properties was calculated.
Dynamics of Magnetization in Frustrated Spin-Chain Systems: Ca3Co2O6
Authors: Korshunov Alexander , Kudasov Yu. B. , Maslov Dmitry Andreevich , Pavlov V.
Published: September 2009

A two-dimensional Ising-like model for the triangular spin-chain lattice, where each spin chain is treated as a rigid superspin, is proposed to investigate the dynamics of magnetization in frustrated triangular spin-chain systems. The superspins are assumed to interact with the nearest neighbours and external agency (heat reservoir and external magnetic field) that causes them to change their states randomly with time. A probability of a single spin-flip process is assumed in a Glauber-like form. This technique allows describing the steps in the magnetization curves observed in Ca3Co2O6 and their dependence on the magnetic field sweep rate and temperature.
Magnetic Phase Diagram and Magnetization Dynamics of Frustrated Spin-Chain Compounds
Authors: Kudasov Yu. B.
Published: September 2009

The magnetic phase diagram of Ising spin chains packed into the frustrated triangular lattice is discussed. A structure of a low-temperature phase depends strongly on interactions between the next-to-nearest-neighbor chains because they lift the degeneracy of the triangular AFM Ising model. That is why, a variety of low-temperature phases is observed in CsCoCl3, Ca3Co2O6, and Sr5Rh4O12. On the contrary, the high-temperature phase (honeycomb AFM structure) is unique. The frustrated Ising chain systems demonstrate an unusual and very slow magnetization dynamics. A model of the magnetization dynamics similar to the Glauber theory is developed.
Superradiation from Molecular Nanomagnets
Authors: Henner V.K. , Kharebov P.V. , Yukalov V.I.
Published: September 2009

The goal of this work is to justify a possibility to obtain and observe coherent spin relaxation—the superradiation (SR) effect—in molecular nanomagnetic structures. We note that giant-spin molecules have the magnetic moments of the order of and possess substantial magnetic anisotropy. Moreover, to invoke SR, such a system should be polarized to a high extent. When put together, these factors rule out the conventional treatment used e.g. for optical SR, and invoke development of novel approaches.
Ferromagnetism in Diluted Magnetic Semiconductors Pb1-x-yGexCryTe
Authors: Skipetrov E.P. , Mikheev M.G. , Pichugin N.A. , Kovalev B.B. , Skipetrova L.A. , Slynko E.I. , Slyn’ko V.E.
Published: September 2009

Magnetic and galvanomagnetic properties of Pb1-x-yGexCryTe (x=0.02-0.20, y=0.01-0.08) solid solutions have been investigated. It was found that the magnetic susceptibility of these alloys contains two contributions: a paramagnetic Curie-Weiss share (T<50 K) due to the paramagnetism of Cr3+ ions and a high temperature ferromagnetic share (T<300 K). Dependence of the concentration of paramagnetic centers on the composition of the matrix was obtained. The magnetic field dependences of the Hall coefficient in the vicinity of the metal-insulator transition were measured and the main parameters of charge carriers in terms of the two-band conduction model were estimated. The experimental results are discussed in the framework of the electronic structure model, assuming varying electrical and magnetic activities of Cr ions as function of germanium content in the alloys.
Magnetic Properties of Mn-Doped ZnO Nanowires
Authors: Granovsky S.A. , Gaidukova I.Yu. , Markosyan Ashot S. , Lu Jia G. , Chien C.J. , Doerr Markus , Papageorgiou T. , Wosnitza J.
Published: September 2009

Structural, magnetic and transport properties of undoped and Mn-doped quasi one-dimensional ZnO nano-wires formed as dendrite crystals of different width have been studied. All Mn-doped nanowires (Mn content 16% and 27 %) exhibit a ferromagnetic behavior, which is significantly temperature dependent. A small magnetic signal detected up to the room temperature is supposed to be due to small amounts of magnetic impurities. Analysis of the temperature dependencies of magnetization shows that the observed magnetic properties can be caused by the host ferromagnetic matrix with Curie temperature TC  40 K.
A Microwave Study of Intrinsic Permeability of Mechanically Activated Powders of Fe-Based Alloys
Authors: Petrov D.A. , Yelsukov Eugene P. , Rozanov Konstantin N. , Lomaeva S.F. , Osipov Andrey V. , Shuravin A.S. , Starostenko S.N. , Ul'anov A.L. , Chulkina A.A. , Surnin D.V.
Published: September 2009

The structure and microwave magnetic performance of Fe, Fe-Si-C, and Fe-Co-Si-C powders fabricated by mechanical milling has been studied. The study was aimed at revealing of the effect of shape, composition, and structure of the powder particles on the microwave frequency dispersion of permeability of the powder-filled composites in the frequency range of 0.1−3 GHz. At low frequencies, below 1 GHz, the main reason causing the differences in the microwave magnetic properties of the powders is the shape of powder particles. At higher frequencies, the magnetic performance is mainly due to the effect of eddy currents and is determined by the size of powder particles. The difference in the composition of the powders under study and, therefore, corresponding differences in intrinsic permeability of these have a minor effect on the microwave magnetic performance as compared to the effects of particle size and shape.
Bias Current Effect on Nonlinear Magnetoimpedance Response in Amorphous Wires with Circular Anisotropy
Authors: Buznikov N.A. , Antonov A.S. , Rakhmanov A.A.
Published: September 2009

The effect of bias current on the appearance of higher harmonics in the nonlinear mag¬netoimpedance in amorphous wires with a circular anisotropy is studied. The rotational model to calculate the voltage response in the case of a weak skin effect is proposed. It is shown that the ap¬plication of the bias current may lead to significant increase of the second harmonic amplitude in the voltage. The conditions of maximum field sensitivity of the second harmonic are found.
Penetration of Microwave Radiation into and through Metallic Powders
Authors: Anzulevich A.P. , Buchelnikov Vasiliy D. , Bychkov Igor V. , Lousguine-Luzgin D.V. , Yoshikawa Noboru , Sato Motoyasu , Inoue Akihisa
Published: September 2009

. It is known that bulk metallic samples reflect microwaves (MWs) while metallic powdered samples can absorb such radiation and be heated efficiently. The present paper shows a direct evidence of penetration of MW radiation into and through a layer of metallic powder and contains theoretical explanation of such behavior.
Magnetic Polaritons on the Interface of Superconductor and Ferromagnet
Authors: Sannikov D.G. , Sementsov D.I. , Zhirnov S.V.
Published: September 2009

In the present paper the dispersive equation for surface polaritons localized at the ferromagnet - high temperature superconductor interface structure have been obtained. The main characteristics dependences upon the external magnetic field are analyzed in the frame of the electromagnetic approach for transverse electric (TE) polarization wave. The analysis for different orientations of superconductor crystallographic axes relative to wave vector directions is carried out.
3D Magnetic Field Modelling and Force Computation of a Permanent Magnet Linear Actuator
Authors: Yatchev Ivan , Hinov Krastyo , Gueorgiev Vultchan
Published: September 2009

Three-dimensional finite element method has been used for modelling of the magnetic field and computation of the electromagnetic force of recently developed permanent magnet linear actuator. The actuator is subject to specific requirements – having four stable positions without supply and maintaining minimum static force during the whole working stroke. The actuator consists of several cores with coils placed on a common yoke and a moving permanent magnet. It is intended for needle driving in a knitting machine. Influence of different factors on the static force characteristic is estimated.
Local Spin Configurations of Fe Atoms in Microinhomogeneous PdMnxFe1-x Alloys
Authors: Serikov V.V. , Kleinerman N.M. , Volkova N.V. , Kourov N.I.
Published: September 2009

The Mössbauer spectra of PdMnxFe1-x alloys obtained at 80 K and at 300 K were studied in the 0.2 < x < 0.8 concentration range, in which there realizes a microinhomogeneous multiphase medium formed by isostructure phases of the constituent compositions: ferromagnetic PdFe (ТС=730 К) alloy undergoing atomic ordering and antiferromagnetic PdMn (TN=815 К) intermetallic compound. Magnetic properties studies evidence the presence of a third presumably noncollinear phase with its own ordering temperature lying below the Curie temperature of the ferromagnetic phase in the 0.2 < x < 0.8 concentration range. The Mössbauer spectra at 300 K exhibit a doublet for antiferromagnetic alloys (x > 0.8) and a sextet at Hhf ~350 kOe for ferromagnetic alloys (x < 0.2). In the intermediate concentration range several peaks 0 < Hhf < 350 kOe have been observed in the P(Hhf) curves, which result from microinhomogeneous multiphase state.
Spin-Dependent Variable Range Hopping Conductivity
Authors: Bozhko A.D. , Demishev S.V. , Glushkov V.V. , Kataeva E.A. , Sluchanko N.E. , Lyapin A.G.
Published: September 2009

Basing on the study of the transport in disordered carbon nanomaterials we argue that the correct description of the magnetoresistance can be obtained in a spin polarization theory, which processes separately the spin and orbital degrees of freedom in hoping conductivity in magnetic field. It is found that the polarization of the spin part of the electron wave function controls the probabilities of the hops between the single and double occupied localized states and, moreover, the spin polarization process can be treated as in the paramagnet with spin S=1/2. The experimental checking of the universal magnetoresistance scaling expected in the spin polarization model is provided.
Temperature Dependence of Magnetization of Lu2Fe17 Compound in Different Structural States
Authors: Korznikova Galia F. , Czeppe Tomasz
Published: September 2009

In the present work we report our studies of temperature dependence of magnetization and structure analysis of Lu2Fe17 samples. The samples revealed various, coarse grained, submicrocrystalline, and nanocrystalline microstructures. It was found that in nanocrystalline state the Lu2Fe17 compound has a higher coercive force, retains phase composition and does not disintegrate during heating. The curves of the temperature dependence of magnetization were recorded for all investigated structural states and indicated that nanocrysatlline sample had a higher Curie point.
Magnetic and Magnetostrictive Properties of Tb-Dy-Ho-Fe-Co Alloys
Authors: Tereshina Irina S. , Nikitin S.A. , Politova G.A. , Ilyushin A.S. , Opolenko A.A. , Burkhanov Gennady S. , Chistyakov O.D. , Palewski T.
Published: September 2009

In this work, the structural and magnetic properties of single-phase TbxDyyHoz(Fe,Co)2 (x + y + z = 1) alloys have been investigated by means of X-ray diffraction, 57Fe Mossbauer spectroscopy, magnetization measurements and a standard strain gage technique. The magnetostriction of TbxDyyHoz(Fe,Co)2 was examined against an applied magnetic field up to 10 kOe in 80 - 400 K temperature range. The Co-containing compounds are found to have high values of magnetostrictive susceptibility due to compensation of magnetic anisotropy in both the rare-earth and 3d transition metals sublattices.
Crystal Structure and Magnetic Properties of Novel Compound PrFe8Ga3C
Authors: Gaviko V.S. , Popov A.G. , Ivanova G.V. , Mushnikov N.V. , Belozerov Y.V. , Ermolenko A.S. , Shreder L.A.
Published: September 2009

We have synthesized a novel intermetallic compound PrFe8Ga3C and studied its structure and magnetic properties. X-ray diffraction analysis revealed that the compound possesses a tetragonal BaCd11-type structure (space group I41/amd). In this structure Ga atoms occupy the same sites as Fe atoms with preferably filling the 4(b) site. Magnetization curves have been measured on the aligned powder samples. Below the Curie temperature TC = 400 K the easy magnetization direction was found to orient within the (100) plane. At 80 K the compound has a spontaneous magnetization of 97 emu/g and anisotropy constant of 4.2107 erg/cm3. At room temperature these values reduce to 78 emu/g and 4.7106 erg/cm3, respectively.
Magnetic/Crystalline Disorder and Transport Phenomena in La0.54Ho0.11((Sr, Ca)(K, Na))0.35MnO3 Manganites
Authors: Craus M.L. , Cornei N. , Lozovan M. , Balasoiu Maria
Published: September 2009

La1-x(Sr, Ca)xMnO3 manganites present a special interest due their high Curie and metal-insulator transition temperatures and the possibility to obtain magnetoresistive sensors able to work near room temperature. We have synthesized two rows of manganites, with La0.54Ho0.11Sr0.35-xKxMnO3 and La0.54Ho0.11Ca0.35-xNaxMnO3 chemical compositions. XRD analysis, performed with a Huber diffractometer at room temperature, indicated that the manganites contain perovskite phases, with Pnma structure. The atomic positions, lattice parameters and some microstructure parameters, as average size of coherent blocks and microstrains, were obtained by using GSAS program. The dependence of the resistivity with temperature and the applied magnetic field was determined by means of four probes method, between 77 and 300 K. The influence of K/Na concentration on the disorder degree (at atomic and crystallite level) and on the transport mechanisms was discussed.
Magnetomechanical Properties of Terfenol-D Powder Composites
Authors: Kaleta Jerzy , Lewandowski Daniel , Mech Rafał , Gąsior Paweł
Published: September 2009

In this work the methodology of determining mechanical and magnetomechanical properties (mainly magnetostriction) of original composite material on epoxy resin matrix and powdered Giant Magnetostrictive Material (Terfenol-D) has been presented. Researches were carried out in order to differentiate properties of the GMM composite with two different volume fraction of Terfenol-D powder (35% and 45%) in comparison with bulk Terfenol-D. Results show that composites magnetostriction highly depends on volume fraction of Terfenol-D powder, and it is few times lower than in monolithic material. Moreover a possible ways of application were indicated.
Finite Element Model of Polyelectrolyte Hydrogels Swelling - Comparison with Experiments
Authors: Paxton Robert A. , Al-Jumaily Ahmed M.
Published: September 2009

The preliminary results of gel swelling experiments are reported, and then compared to predictions made by a recently-developed finite element model (FEM). This model utilises energy transport between different energy domains, and is being used to simulate gel swelling dynamics. Initial experiments have revealed the model does capture the general behaviour of polymer hydrogel swelling dynamics and further improvements are necessary for better accuracy.
Size Dependent Interface Energy of Nanomaterials
Authors: Lu H.M.
Published: September 2009

The reduction of size of the low dimensional materials leads to a dramatic increase of surface-to-volume ratio. The properties of a solid are essentially controlled by related surface/interface energies. Although such changes are believed to dominate behaviors of nanoscale structures, little experience or intuition for the expected phenomena, especially the size dependent properties and their practical implications, are modeled. In this contribution, the classic thermodynamics as a powerful traditional theoretical tool is used to model different bulk interface energies and the corresponding size dependences where emphasis on the size dependence of interface energy is given, which is induced by size dependence of coherent energy of atoms within nanocrystals. It is found that solid-vapor interface energy, liquid-vapor interface energy, solid-liquid interface energy, and solid-solid interface energy of nanoparticles and thin films fall as their diameters or thickness decrease to several nanometers while the solid-vapor interface energy ratio between different facets is size-independent and is equal to the corresponding bulk ratio. The predictions of the established analytic models without any free parameter, such as size and temperature dependences of these four kinds of interface energies, are in agreement with the experimental or other theoretical results of different kinds of low dimensional materials with different chemical bond natures.
Monocrotaline‐Induced Pulmonary Hypertension in Wistar Rats
Authors: Rey Markus , Hess Patrick , Clozel Martine
Published: September 2009

Pulmonary arterial hypertension (PAH) is a debilitating and often fatal disease characterized by a progressive increase in pulmonary vascular resistance that leads to right ventricular failure. Described in this unit is an in vivo model of monocrotaline‐induced pulmonary hypertension in rats that can be used to assess the effects of antihypertensive agents on pulmonary artery pressure and right ventricular hypertrophy. Curr. Protoc. Pharmacol. 46:5.56.1‐5.56.11. © 2009 by John Wiley & Sons, Inc.
Detecting concealed information with reaction times: Validity and comparison with the polygraph
Authors: Verschuere Bruno , Crombez Geert , Degrootte Tessie , Rosseel Yves
Published: September 2009

The Concealed Information Test is used to assess recognition of information that the examinee cannot or does not want to reveal. Physiological measures recorded with the polygraph have shown to be highly valid measures of concealed information. Research suggests that a reaction‐time (RT) based test may also successfully reveal concealed information. Due to its simplicity, an RT‐based test has great advantages for applied testing. In the present study, we assessed the validity of the RT‐based test for concealed information detection, and compared its discriminative power with the polygraph. Thirty two participants in a feigned amnesia study were promised a financial reward when successfully concealing autobiographical information. Participants performed an RT‐based test, and a polygraph test. The data support the validity of the RT‐based test for concealed information detection, and indicate its discriminative power is similar to the polygraph. Our data confirm the potential of the RT‐based test. Copyright © 2009 John Wiley & Sons, Ltd.
Observation of a Charge Transfer State in Low‐Bandgap Polymer/Fullerene Blend Systems by Photoluminescence and Electroluminescence Studies
Authors: Zhou Yi , Tvingstedt Kristofer , Zhang Fengling , Du Chunxia , Ni Wei‐Xin , Andersson Mats R. , Inganäs Olle
Published: September 2009

The presence of charge transfer states generated by the interaction between the fullerene acceptor PCBM and two alternating copolymers of fluorene with donor–acceptor–donor comonomers are reported; the generation leads to modifications in the polymer bandgap and electronic structure. In one of polymer/fullerene blends, the driving force for photocurrent generation, i.e., the gap between the lowest unoccupied molecular orbitals of the donor and acceptor, is only 0.1 eV, but photocurrent is generated. It is shown that the presence of a charge transfer state is more important than the driving force. The charge transfer states are visible through new emission peaks in the photoluminescence spectra and through electroluminescence at a forward bias. The photoluminescence can be quenched under reverse bias, and can be directly correlated to the mechanism of photocurrent generation. The excited charge transfer state is easily dissociated into free charge carriers, and is an important intermediate state through which free charge carriers are generated.