bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Electropulsing Treatment on the Precipitation Behaviour of Grain Boundary Carbides in GH3044 Alloy
Authors: Liu Yang , Wang Lei , Wang Yu Chen , Liu Hong Yan , Chen Xue Jiao , Yu Yan
Published: June 2010

The effects of electropulsing treatment on the precipitation behaviour of grain boundary carbides in GH3044 alloy were investigated. The results showed that the initial temperature of precipitation of M23C6 type carbides on grain boundary could be decreased by electropulsing treatment under the condition of high current density of 10.0kA/mm2 with a frequency of 5Hz and pulse width of 15s. The volume percentage of M23C6 type carbide was greatly increased to 274.60% comparing with that of the aging treatment at the same temperature. However, the precipitation of M23C6 type carbide was inhibited by electropulsing treatment under the condition of high frequency of 45Hz with the current density of 2kA/mm2 and pulse width of 15s. The volume percentage of M23C6 type carbide was decreased to 18.81% comparing with that of the aging treatment at the same temperature. It has been found that the diffusion of solute atom in the alloy can be promoted by the electric effect with the electropulsing. As a result, the thermodynamic condition and kinetics of the precipitation of M23C6 type carbide were changed, and both the initial and peak temperatures of precipitation were decreased.
The Effect of Refractory Elements on Microstructure and Mechanical Properties of Ni3(Si,Ti) Intermetallic Alloys
Authors: Kai Akiko , Imajo Daiki , Kaneno Yasuyuki , Takasugi Takayuki
Published: June 2010

Microstructure, mechanical properties and cold workability of quaternary Ni3(Si,Ti) intermetallic alloys with L12 structure, which were alloyed with two atomic percent of a refractory element X (X: Hf, Ta and W), were investigated. The Ta-added Ni3(Si,Ti) alloy showed an L12 single phase microstructure, while the microstructure of the Hf-added alloy was comprised of Ni5Hf and/or Ni3Hf intermetallic dispersions in the L12 matrix, and that of the W-added alloy consisted of fcc Ni solid solution phase within the L12 grain. In the homogenized condition, hardness increased in the order of the Hf-added, the Ta-added and the W-added alloys. The hardenings of the Hf-added and the Ta-added alloys were attributed to second-phase dispersion hardening and distinctive solid solution hardening, respectively. Among these alloys, only the W-added alloy was successfully cold-rolled to thin sheet with a thickness of 200 m. It was found that both room-temperature and high-temperature tensile strength of the W-added alloy sheet was enhanced compared with that of the unalloyed Ni3(Si,Ti) sheet. Also, high-temperature tensile ductility was significantly improved in the W-added alloy sheet, by suppressing the propensity of brittle intergranular fracture.
The Role of Interfacial Precipitates on Creep Behaviour of Power Metallurgy (PM) Ti-48Al-2Cr-2Nb+1W Alloy
Authors: Seo Dongyi , Bulmer Scott , Saari H. , Zhu Han Liang , Au Peter
Published: June 2010

Pre-alloyed powders with a nominal composition of Ti-48Al-2Cr-2Nb+1W were consolidated by hot isostatic pressing (HIP). After the HIP process, a step cooled heat treatment (SCHT) with a carefully controlled cooling rate was applied to homogenize the HIP’ed microstructure and produce a fully lamellar microstructure. Following the SCHT, various isothermal aging at 950 °C and step aging processes form interfacial precipitates at the lamellar interfaces. The morphology, size, and distribution of the precipitates are dependent on the aging condition. Creep tests were carried out in air at 760 °C and 276 MPa to investigate the effect of interfacial precipitates. Primary creep resistance and creep life of the 8 and 144 hr aged conditions are improved substantially compared to the unaged condition due to the existence of the interfacial precipitates. However, the step aging process improves the creep resistance only slightly, probably because of the size and distribution differences of the interfacial precipitates compared to the 144 hr aged condition. Microstructure control is important since it has a substantial influence on creep behavior, especially primary creep resistance.
Microstructure and Creep Behavior of a Single Crystal Nickel-Base Superalloy with [011] Orientation
Authors: Tian Su Gui , Zhang Shu , Yu Li Li , Yu Hui Chen , Qian Ben Jiang
Published: June 2010

An investigation has been made into the microstructure and creep behaviors of [110] oriented single crystal nickel-base superalloy. Results show that, after a full heat treated, the cubic  phase is coherently embedded in the matrix and regularly arranged along the <100> orientation. During creep, the cubic phase in the alloy is transformed into the rafted structure lying 45 relative to the direction of the applied stress. Under the condition of the applied stress of 137 MPa at 1040°C, the alloy displays a higher strain rate and shorter creep lifetime. The deformation mode of the alloy during creep is dislocations activated within the matrix channels and the rafted phase. Dislocation slip activated easily on the Roof-type channel is thought to be the main reason of the alloy having higher strain rate and shorter creep lifetime.
Statistical Analysis of Creep Crack Growth Behavior in Modified 9Cr-1Mo Steel
Authors: Kim Seon Jin , Kim Woo Gon , Jung Ik Hee , Kim Yong Wan
Published: June 2010

In this paper, a series of statistical studies were conducted on creep crack growth behavior of Grade 9Cr-1Mo steel for next generation reactor. Creep crack growth tests were performed on pre-cracked compact tension (CT) specimens under the applied load ranges from 3800 to 5000N at the identical temperature condition of 600oC. The creep crack growth behavior has been analyzed statistically using the empirical equation between crack growth rate da/dt and C* parameter, namely da/dt=B(C*)q. First, the determination methods of B and q obtained from experiments were investigated by the least square fitting method and the mean value method. The probability distribution functions of B and q have been investigated using the normal, log-normal and Weibull distribution. The constant B and q are followed well 2-parameter Weibull. Second, the creep crack growth rate data were generated by Monte-Carlo simulation method assuming the 2-parameter Weibull in B and q parameters. The probability distribution of creep crack growth rate for arbitrary C* parameter values seems to follow well Weibull distribution.
Effects of Ferrite Content on the Tensile Strength and Impact Toughness of 2.25Cr-1Mo-0.25V Steels
Authors: Kim Tae Kyu , Han Chang Hee , Kim Sung Ho , Kwon Hee Kyung , Kim Dong Jin
Published: June 2010

In order to evaluate the effects of a pro-eutectoid ferrite content on the tensile strength and impact toughness of 2.25Cr-1Mo-0.25V steels, several samples with a different area fraction of ferrite in the range from 0 to 80% were prepared by a control of cooling rate from an austenitization heat treatment temperature of 930oC. The steels were then tempered at 690oC, followed by a heat treatment at 705oC as a simulation of postweld heat treatments. The results of microstructural observation indicated that the ferrite was uniformly distributed in the bainitic matrix. The results of tensile tests revealed that the tensile strength at room temperature and 450oC was slightly reduced with the ferrite content of up to 20%, but it was considerably reduced with the ferrite content of 80%. On the other hand, the results of impact tests at -60, -80 and -100oC indicated that the impact toughness was rapidly degraded with increasing ferrite content. These results attributed to the segregation of carbides in the bainitic matrix as a result of the formation of ferrite phase with low solubility of carbon. It is concluded that the ferrite content in the 2.25Cr-1Mo-0.25V steels could exert a sensitive inference on the impact toughness rather than on tensile properties.
High Temperature Oxidation Behavior of Si-Mo Ferritic Ductile Cast Iron
Authors: Choe Kyeong Hwan , Lee Sang Mok , Lee Kyong Whoan
Published: June 2010

High temperature oxidation behavior of Si-Mo ferritic ductile cast iron was investigated in the point of the effect of chromium and vanadium addition. The addition of Cr promoted the formation of as-cast pearlite around carbide which exists in cell boundary, which was eliminated during annealing process. The addition of vanadium promoted the precipitation of tiny carbide and reduced the grain size of ferrite. As the test temperature increased, the change of volume increased, on the other hand, the change of weight decreased above 1173K. In the case of Cr added specimen, the change of weight decreased with the increase of test temperature because of the presence of Cr oxide layer. The vanadium added specimens showed higher increase in the weight and volume change. The oxide layer of vanadium added specimen had very porous structure and showed severe internal oxidation. It is due to the catastrophic oxidation characteristic of vanadium alloyed ferrous alloy.
Precipitation Sequence in an Al-Si-Mg Foundry Alloy
Authors: Rinderer Barbara , Couper Malcolm , Xiong Xiang Yuan , Gao Sam X. , Nie Jian Feng
Published: June 2010

It is often assumed that the precipitation sequence and phases in Al-Si-Mg foundry alloys, such as A356 with 7 wt%Si, are similar to those in wrought 6xxx Al-Mg-Si alloys, such as 6063. The foundry alloys have been less extensively studied due to added difficulties in sample preparation, resulting from the high volume fraction of coarse particles of spheroidised eutectic silicon. Recent work has been successful in studying the precipitation sequence in a foundry alloy containing 0.45 wt%Mg. The work highlights some differences and similarities between foundry and wrought alloy precipitation, which may have implications for alloy design and heat-treatment.
Inoculation during Metal Castings: Beyond Grain Refining
Authors: Qiu Dong , Zhang Ming Xing
Published: June 2010

Inoculation is the most common grain refining technique during metal/alloy castings. However, only a small fraction, typically 1~2%, of inoculants serve as nucleation sites while most of them do not participate in the nucleation event and hence they are usually termed ‘inactive’ inoculants. But ‘inactive’ does not mean ‘useless’. Our recent studies revealed some extra merits of these ‘inactive’ particles in Mg-Al-Y cast alloys. The current results represent a new approach to microstructure design through manipulation of inoculated particles during castings.
Microstructure and Mechanical Properties of Extruded Mg-Zn-Ca Alloy
Authors: Zheng Ming Yi , Tong L.B. , Xu S.W. , Hu X.S. , Wu K. , Kamado S.
Published: June 2010

The as-cast Mg - 5.25 wt.% Zn - 0.6 wt.% Ca alloy was extruded at different extrusion temperatures (270, 300, and 330 °C). The extrusion temperature has a significant effect on the grain size, texture and mechanical properties of the Mg-Zn-Ca alloy. Upon extrusion, the as-cast coarse grains underwent pronounced grain refinement and the second phases were broken up and formed stringers in the extrusion direction. With the decreasing extrusion temperature to 270 °C, the grain size of the alloy was refined to about 1.5 μm, basal texture became stronger, which led to the higher tensile strength and moderate elongation to failure.
Texture and Mechanical Properties of AZ31 Magnesium Alloy Sheets Processed by Symmetric/Asymmetric Combination Hot-Rolling
Authors: Horiuchi J. , Inoue Hirofumi , Takasugi Takayuki
Published: June 2010

Conventional symmetric rolling enhances yield strength by forming basal texture, while asymmetric rolling can improve formability by inclining the c-axis of hcp crystal. In this study, the combination rolling consisting of symmetric and asymmetric hot rolling has been performed to simultaneously improve formability and maintain high strength of AZ31 magnesium alloy sheet. The symmetrically/asymmetrically combination hot-rolled and annealed sheet exhibits a broadened texture having double peaks with tilt angles of 0º and 40º from ND toward RD with respect to the c-axis. Correspondingly, this sheet shows relatively high yield strength of 123 MPa and large elongation of 24.7%. As for cup drawing test, the conventional warm-rolled sheet is barely formed at 175 °C, but the symmetrically/asymmetrically combination rolled sheet can be formed at temperature as low as 75 °C. These results indicate that the symmetric/asymmetric combination hot-rolling leads to a unique texture with good balance of formability and strength.
Sound Insulation Study on Mg Sheet and Mg Honeycomb Panels
Authors: Quan Gao Feng , Liu Zhao Ming , Gu Xiue , Yan Feng
Published: June 2010

The sound insulation experiments were conducted to magnesium alloy sheet and magnesium honeycomb panels. It is found that the sound insulation coefficient (transmission loss, TL) of honeycomb panel is higher than that of the sheet in full sound frequency spectra, and TL spectra of both single sheet and honeycomb panel is similar with the sound frequency, thus the TL is increased obviously with the frequency. Comparably, TL of honeycomb panels is always higher than that of the sheets, especially at middle range of frequencies 6 kHz~10 kHz, the sheet has a TL of 27 to 31dB, and the honeycomb panel has 34-39 dB. The parameters of honeycomb cores is discussed briefly.
Improvement of Corrosion Resistance of Extruded Mg-Zn-Y Mg/LPSO Two-Phase Alloys by Fourth Element Addition
Authors: Izumi Shogo , Yamasaki Michiaki , Kawamura Yoshihito
Published: June 2010

This paper deals with the influence of fourth element addition to the high strength Mg-Zn-Y extruded alloys with long period stacking ordered (LPSO) phase on corrosion resistance and surface film formation. Salt water immersion test, SEM observation, and EDX analysis are performed on Mg97Zn1Y2(at.%), Mg97Zn1Y1.9La0.1 and Mg97Zn1Y1.9Al0.1 alloys. The Al or La addition to the extruded Mg97Zn1Y2 alloy is effective for the formation of thin, dense and uniform surface layer, resulting in improvement of corrosion resistance.
Modelling of the Metal/Mould Interactions in the DC Casting Process for Aluminium and Magnesium
Authors: Prasad Arvin , Bainbridge Ian F.
Published: June 2010

The process of direct chill (DC) casting of aluminium and magnesium alloys is regarded as a mature technology. The thrust of more recent work to understand and upgrade the technology has been centred on developing models of the process, the most advanced of which (e.g., Alsim and Calcasoft) have been used to examine what may be considered macro-features of the process (macro-segregation, hot cracking, etc.). These models, being macroscopic, rarely elaborate on the role of mould-wall heat transfer in the DC casting process. As part of the work on DC casting being conducted at CAST, for the investigation of small scale features of the process (e.g. heat extraction through the mould wall), a 2D finite Difference model of the process near the mould-wall region has been developed. The basic features of the model are described and initial results outlined.In particular, the effect of mould-wall heat transfer on the solid shell formed during the steady state regime of DC casting will be presented.
Effect of Hydrogen Content on Superplastic Forming and Diffusion Bonding in Ti600 Alloy
Authors: Wang Xiao Li , Zhao Yong Qing , Hou Hong Liang , Zeng Wei Dong
Published: June 2010

The superplastic forming and diffusion bonding (SPF/DB) of hydrogenated Ti-6Al-2.8Sn-4Zr-0.5Mo-0.4Si-0.1Y (Ti600) alloys were carried out in the temperature range of 1073-1213K under 1.5MPa gas pressure. The effects of hydrogen contents and diffusion temperature on welding-on ratio of SPF/DB and microstructure of interface and matrix in Ti600 alloy were investigated by OM and SEM. According to the experimental investigation, when the parameters of SPF/DB were as follows: T=860°C, P=1.5MPa and t=70min, the welding-on ratio of Ti600 alloy with hydrogen 0.5wt% was 100 percent. However, the physical contact of Ti600 alloy without hydrogen which was related to plastic forming could not occur. Moreover, the size and amount of voids at the diffusion bonding interface decreased and diffusion bonding quality improved gradually with the increase of hydrogen content and diffusion temperature, which was attributed to the decrease of phase transformation temperature and flow stress of plastic forming as well as the release of hydrogen. After SPF/DB, the recrystallization of joint grains through the interface was formed, and the matrix of hydrogenated Ti600 alloy changed.
The Ageing Behavior of Titanium Alloy Ti-10V-2Fe-3Al
Authors: Al-Salihi Huda , Bettles Colleen J. , Muddle Barry C.
Published: June 2010

A good combination of high strength and hardenability makes the alloy Ti 10V-2Fe-3Al a prime candidate for applications in the aerospace arena. However, these properties are very dependent on a post-forming heat treatment. The overall objective of this work is to determine the effect of prior deformation on the aging behaviour. In this particular study, the influence of the heat treatment, either solution and/or aging, on the microstructures, and consequently on the mechanical properties, without introduced strain is reported. Various solution heat treatments have been conducted, either in the β phase or in the (α+β) phase field, followed by rapid quenching or slow cooling, and aging treatments at different temperatures (250, 350, 400, 500C°) above and below the ω-transus temperature. Vickers hardness indentations were used to follow the precipitation hardening behaviour, and mechanical properties were determined using a shear punch test. The aging response is dependent not only on the presence of the athermal ω phase but also on the proximity of the aging temperature to the ω-transus. Most treatments showed an unusual initial softening behaviour prior to age hardening, however this appears to be related again to the composition and fraction of the β phase retained after solution treatment.
Influence of Heat Treatment on the Pseudoelastic Behaviour of a β Ti-25Nb-3Zr-3Mo-2Sn Alloy
Authors: Kent Damon , Wang Gui , Zheng Li Hui , Yu Zhen Tao , Dargusch Matthew S.
Published: June 2010

The elastic response of a metastable β titanium alloy, Ti-25Nb-3Zr-3Mo-2Sn, is characterised. The effects of processing and heat treatment on phase composition and mechanical behaviour are reported. The alloy exhibits pseudoelastic behaviour which is related to the reversible formation of the stress induced α" phase. The solution treated condition displays the greatest pseudoelasticity and the hot rolled condition the least. Tensile deformation reduces the modulus of the alloy. This is due to increases in the relative proportions of the low modulus α" phase.
Assessment of Durability and Damage Tolerance of β-Annealed Ti-6Al-4V
Authors: Shekhter Alex , Barter Simon A. , McDonald Marcus , Wanhill R.
Published: June 2010

-annealed Ti-6Al-4V ELI alloy has a special chemical composition and manufacturing process, intended to optimise its fatigue and fracture properties. This alloy is used in primary fatigue-critical structures of advanced military aircraft, but little has been generally published about its properties, particularly the fatigue and crack growth behaviour under service loading. A test programme has been set up to assess the fatigue durability and damage tolerance properties of the alloy, in the context of the two most relevant analysis methods. The first is strain – life analysis, used to estimate safe lives (durability). The second is fatigue crack growth analysis, used to assess the damage tolerance behaviour. This paper presents preliminary results of the test programme.
Drawability of Ti-6Al-4V Sheet at Elevated Temperatures
Authors: Park Nho Kwang , Park Jin Gee , Seo Sang Hyun , Kim Jeoung Han
Published: June 2010

Titanium and its alloys are difficult-to-form materials due to limited slip system and plastic anisotropy. Titanium is also prone to change in color due to oxidation at high temperatures. It is thus advisable to conduct deep drawing of titanium and its alloys at temperatures below 600°C. In this study, the drawability of Ti-6Al-4V sheet is evaluated in respect to the process parameters such as forming temperature, forming speed, and blank holding force at elevated temperatures. It is shown that the limit drawing ratio (LDR) increases with increasing temperature, but varies insignificantly with forming speed. The development of residual stresses in the wall of drawn cups during deformation was evaluated.
Microstructural Characteristics of Electron Beam Processed Al-2Sc
Authors: Tomus Dacian , Qian Ma , Yu Peng , Brice Craig A. , Bettles Colleen J. , Muddle Barry C.
Published: June 2010

Plate samples of Al-2Sc were processed with an electron beam (EB) gun in a vacuum of 10-3 Pa at 50kV and 30 µA. EB processing suppressed the formation of primary Al3Sc, altered the morphology of the eutectic (Al)-Al3Sc, and increased the solubility of Sc in the eutectic (Al). In addition, its cyclic heating effect induced the precipitation of Al3Sc. EB processing resulted in more profound hardening than conventional high temperature solid solution and ageing.
Quantitative Analysis of Precipitate Compositions in an Al-Li-Mg-Cu Alloy Using Atom Probe Tomography
Authors: Xiong Xiang Yuan , Moutsos Stavroula , King Russell , Muddle Barry C.
Published: June 2010

The composition of  precipitates in aluminium alloy 8090 has been analysed using a 3 dimensional atom probe with fast data acquisition rates. The effects of experimental conditions for the quantitative atom probe analysis have been examined in detail. The results show that i) lithium is prone to preferential DC field evaporation at temperatures > 25K and with a pulse fraction < 20%; ii) the lithium concentration of  precipitates can vary from precipitate to precipitate, ranging from 19.1 to 25.3 at.%, and iii) the stoichiometric composition of the  phase can be obtained provided that the probing temperature is  25K and pulse fraction is  20%.
Morphological Variation of Fe/Cr-Rich Intermetallic Phase in Recycled Al-Si Alloy as a Function of Solidification Rate: Time-Resolved Radiography
Authors: Kim Bong Hwan , Lee Sang Mok , Yasuda Hideyuki
Published: June 2010

Effects of Cr addition on morphology of β-Al5FeSi phase formed in recycled aluminum alloy were studied as a function of cooling rate by technology of time-resolved radiography. The Cr addition to iron-contaminated recycled alloys modified the needle-like β-Al5FeSi into faceted dendritic α-AlFeCrSi phase in condition of conventional casting. Time-resolved radiography of the formation of α-AlFeCrSi revealed the transition of its morphology from polyhedron at about 10K/min of cooling rate to equiaxed dendrite of faceted arms at about 50K/min. of cooling rate.
Solidification Structure and Sound Absorbability of A356 Alloy Foams
Authors: Li Yan Xiang , Yuan W.W. , Chen X.
Published: June 2010

Metallic foams of A356 alloy with a uniform porosity of 75-85% were produced with the melt foaming process. The microstructure inside the foam cell walls was experimentally studied. It is found that the microstructure is greatly different from the as-cast structure of the base alloy. It is believed that the thickening process with calcium, the adding of foaming agent and the mixing process during the production process all play important roles on the solidification microstructure of the cell walls. The morphology and grain size of primary α-phase, the amount and morphology of eutectic silicon, the distribution and size of CaSi2Al2 and residual titanium hydride particles were studied. The sound absorption coefficient of the alloy foams was measured. Two methods, drilling small holes and compressing the foam, have been developed to improve the sound absorbability of the alloy foam in low and middle frequency ranges.
Influence of Dynamic Viscosity on Automatic Dynamic Balance
Authors: Bogdevicius Marijonas , Janutėnienė Jolanta
Published: June 2010

The paper deals with analysis of dynamic stability and behavior of automatic dynamic balance (ADB) by applying theoretical approach. Differential equations of the considered system were established using Lagrange equation. Numerical analysis of the dynamic equations was performed and influence of dynamic viscosity coefficient on self-balancing process was estimated. It is demonstrated that the balancing time decreases in non-linear character. The optimal value of dynamic viscosity for achieving minimal balancing time can be determined for the analyzed system.
Design of Sensor System for the Linear Actuator of Stewart Platform
Authors: Houška Pavel , Březina Tomáš
Published: June 2010

The article deals with description of design of sensor system for linear actuators. These constitute a part of a parallel kinematic machine based on a structure of a Stewart platform. The machine is intended for testing of bone implants in biomechanical and medical practice. The developed Stewart platform presents a mechatronic system. Hence the design of mechatronic systems known as a V-model was used. The system of sensors has been developed since the middle phase of the Stewart platform development.
Control Method for Elimination of Self–Excited Oscillations during Turning
Authors: Březina Tomáš , Vetiška Jan , Blecha Petr , Houška Pavel
Published: June 2010

The oscillations occurring between the tool and the machined area during the turning process lead to degradation of the machined surface, cause poor geometric accuracy, accelerate tool wear and generate noise. This paper deals with the possibility of elimination of these self-excited oscillations by changing the parameters of the turning process. On the basis of the regenerative principle of self-excited oscillation generation, a computer model of the machining process was developed. Furthermore, a PID controller was proposed to control the compensation of the vibrations and its suitability for elimination of the self-excited oscillations was verified experimentally.
Stewart Platform Model with Uncertain Parameters
Authors: Březina Lukas , Březina Tomáš
Published: June 2010

The paper deals with development of uncertain dynamics model of a six DOF parallel mechanism (Stewart platform) suitable for H-infinity controller design. The model is based on linear state space models of the machine obtained by linearization of the SimMechanics model. The linearization is performed for two positions of the machine in its workspace. It is the nominal position and the position where each link of the machine reaches its maximal length. The uncertainties are then represented as differences between parameters of corresponding state-space matrices. The uncertain state space model is then obtained using upper linear fractional transformation. There are also mentioned several notes regarding H-infinity controller designed according to the obtained model.
Some Aspects of Bearing Noise Generation
Authors: Bučinskas Vytautas , Mirzaei Sahar , Kirchner Karsten
Published: June 2010

Problem of ball bearing and roller bearing noise generation is important in present technology level, and its solution stands in front for a new machine designer. New materials of bearings create new problems of bearing noise generation, so research of noise and vibration generation mechanism in necessary. Problem of lubrication gives significant influence to vibration and noise generation in bearings, so in common task of bearing work vibration is quite complex and requires experimental verification of theoretical ideas. This paper is intended to cover noise generation mechanism of ceramic bearings in comparison to steel ones and evaluate influence of bearing lubricant with different properties. There are presented design of experimental workbenches, experimental research procedure and results from research. Experimental results material is presented graphically and numerically. Finally, conclusion on problem and results of experimental research are made.
Attenuation-Frequency Characteristics of Beam Systems in Spatial Motion
Authors: Zolkiewski Sławomir
Published: June 2010

Attenuation-frequency characteristics of the beam systems in spatial motion are presented in this paper. The characteristics enclose mutual relations between particular components of angular velocity and amplitude of vibrations, expressed by the value of dynamical flexibility. Beam systems consisting of homogeneous beams with symmetrical cross-sections undergoing spatial motion are considered. The systems vibrate transversally and beams are considered in spatial motion treated as transportation.
Numerical Analysis and Experimental Research of a Compliant Minigripper
Authors: Noveanu Simona , Mândru Dan , Lungu Ion , Csibi Vencel Iosif
Published: June 2010

The compliant mechanisms are mechanical devices which provide smooth and controlled motion guidance due to the deformation of some or all of the components. In this paper an original compliant minigripper is designed and analyzed. An experimental prototype of the compliant minigripper was developed. It is characterized by a compact design and easy connection to the piezoelectric actuator that amplifies the input displacement.
Implementation of the Type-2 Fuzzy Controller in PLC
Authors: Dominik Ireneusz
Published: June 2010

The main aim of the presented research work was to develop type-2 fuzzy logic controller, which by its own design should be “more intelligent” than type-1. Along with the intelligence it should provide better results in solving a particular problem. Type-2 fuzzy logic controller is not well-known and it is rarely used at present. The idea of type-2 fuzzy logic set was presented by Zadeh in 1975, shortly after the presentation of type-1 fuzzy set. At the beginning scientists and researchers worked on type-1. Only after developing type-1 the attention was directed towards the type-2. The first applications of type-2 fuzzy logic in control appeared in 2003. The fuzzy logic controller type-2 was tested experimentally by controlling a non-linear object: a shape memory alloy (SMA) actuator DM-01PL, made by Miga Motor company, which despite small size distinguishes itself by its 9 N strength. Comparison of experimental data of the fuzzy logic controller type-2 and type-1 clearly indicates the superiority of the former, particularly in reducing signal overshoots.
Properties of Duplex Stainless Steel Surface Layers after Burnishing Process
Authors: Łabanowski Jerzy , Ossowska A.
Published: June 2010

This paper investigates stress corrosion cracking resistance of cold worked layers of 25 Cr duplex stainless steel grade UR52N+. The surface layers were processed through burnishing treatment. The residual stresses at surface layers were determined using grazing angle incidence X-ray diffraction method (g-sin2 Ψ). Corrosion tests were performed with the use of Slow Strain Rate Test technique in boiling 35% MgCl2 solution. It has been demonstrated that burnishing treatment increases corrosion resistance of the steel. Stress corrosion cracking resistance depends on the magnitude of cold work at surface layers. High level of cold work diminishes corrosion resistance.
Cavitation Wearing of the SUPERSTON Alloy after Laser Treatment at Cryogenic Conditions
Authors: Majkowska Beata , Serbiński Waldemar
Published: June 2010

The purpose of this paper is to demonstrate the method of laser remelting at cryogenic conditions of the SUPERSTON alloy and its influence on microstructure and cavitation wearing. The cavitation test was performed using the rotating disc facility in IPM PAN Gdansk. During the cavitation test, the mass loss of the material with different parameters of laser remelting was determined. Surface and cross-section microstructure of the SUPERSTON alloy after laser treatment and cavitation test were observed by scanning electron microscope. The cavitation resistance of the remelted SUPERSTON alloy was approximately 40% higher in comparison to the base material.
FEM Modeling of Failure of a Foam Single Cell
Authors: Szymczyk Wiesław , Miedzińska Danuta
Published: June 2010

. The paper deals with the numerical analysis of foam materials. Open cell foam is investigated. Numerical simulations enable prediction of failure process and assessment of effective properties of the modeled foam structures [1]. Metal as well as polyurethane foams exhibit interesting properties. They are light, possess good acoustic and/or magnetic isolation, have ability to absorb energy of vibration and impacts [2]. They are used for sandwich panels, hit absorbers (i.e. as elements of buffer constructions in rail vehicles), fillers of construction parts, bodies of vehicles (i.e. floating combat vehicles), dividing walls on vessels and others. Specially prepared open cell foams demonstrate auxetic properties [3] and shape memory effect [4]. Such materials are very good for seats in aircrafts, which may protect pilots and passengers during crashes and restrict heavy backbone injuries. Foams are also applied for filtering purposes. Foams themselves or in combination with different types of fillers (i.e. elastomers) or ceramic reinforcement may be used for impact energy absorbing panels for military purposes (protection against explosion shock wave and splinters).
Influence of Ageing Process on Structure and Mechanical Properties of the T24 Steel
Authors: Golański Grzegorz
Published: June 2010

The paper presents results of research on the influence of ageing on the microstructure and mechanical properties of T24 steel. The examined material was in the form of longitudinal samples taken from a pipe section (with the pipe size of 44.5x6.7 mm). The research is focused on degradation of the base material (T24 steel) where the steel samples, after initial heat treatment, were aged at the temperature of 580°C and time up to 6000hrs in a furnace with air atmosphere. This contribution summarizes the experimental results of mechanical and structural measurements and provides relations between them.
Asymmetric Process of Plate Rolling Analysis
Authors: Kawałek Anna , Dyja Henryk , Knapiński Marcin
Published: June 2010

This work reports the results of theoretical analysis of asymmetric rolling process of plates in the finishing mill of plate rolling. Its aim was to determine the influence of asymmetry velocity of working rolls on the value and direction of bending radius of strip flowing from the deformation zone. Variables of the considered process were: rotational speed asymmetry factor av, strip shape factor h0/D and reduction of cross-sectional area ε.
Insights on the geology of the world-class Roberto Gold Deposit, Eleonore Property, James Bay, Quebec
Authors: Ravenelle J -F , Dubé B , Malo M , McNicoll V , Nadeau L , Simoneau J
Published: June 2010

The world-class Roberto gold deposit is an atypical gold deposit located in an underexplored part of the Superior Province. The purpose of this paper is to present a preliminary geological description of deposit and provide insights on geological features that
may have played a role in its formation and can be used to help exploration programs. The deposit is located within a km-scale F2 fold hinge that affects upper-greenschist to amphibolite-facies turbiditic metagreywacke and paragneiss. Gold mineralization is primarily confined to a series of
sub-parallel decameter-scale-wide mineralized zones and is associated with an hydrothermal system characterized by calc-silicate veins and metasomatic replacement zones, potassic alteration, and tourmaline. The principal mineralized zone (Roberto) consists of a stockwork of quartz ± actinolite
± diopside ± biotite-arsenopyrite-pyrrhotite veins and quartz-dravite-arsenopyrite veinlets, contained within microcline (potassic alteration) and dravite replacement zones. While most of the alteration and mineralized zones are deformed by structures attributed to D2, some occurrences
appear to be controlled by D2 structures; gold mineralization is thus interpreted as being pre- or early-D2. Although geochronological data allow to refute the hypothesis that Roberto (<2675 ± 6 Ma) is associated with the nearby Ell Lake diorite (2705 ± 1.9 Ma), the potential
input from magmatic fluids should not be blindly discarded, as indicated by the presence of potentially younger porphyritic intrusions and multiple generations of pegmatites, some of which potentially being contemporaneous with a part of the mineralization or its
remobilization.
Nitrogen (15N) retention in small Thalassia hemprichii seagrass plots in an offshore meadow in South Sulawesi, Indonesia
Authors: Stapel Johan , Hemminga Marten A. , Bogert Cornelis G. , Maas Yvonne E. M.
Published: June 2010

Nitrogen retention was investigated during 240 d in 1 × 1 m field plots of the tropical seagrass Thalassia hemprichii. Shoots were enriched with 15N by brief exposure of the leaves to an elevated concentration of 15N ammonium in the water column. Hereafter, the 15N absorbed in the seagrass system declined rapidly. The decline was initially dominated by the loss of 15N in detached leaf fragments. Of the lost leaf fragments, 19% were recovered within the boundaries of the experimental plots, and 25% were deposited outside these boundaries but inside the seagrass meadow. Of the remaining 56%, the fate could not be resolved, but export from the meadow is probably limited to ~10%. During the course of time, the 15N half‐life increased from 1 to ~2 months because of 15N accumulation in compartments from which it was not easily exported (roots, rhizomes, and sedimentary detritus). The limited nitrogen retention in the seagrass plots is ascribed to the combined effects of a major allocation of nitrogen to leaf production, restricted nitrogen resorption from senescent leaves (28% of the gross N demand), and a dynamic environment facilitating detachment and export of leaf fragments from the experimental plots. At the scale of the whole meadow, however, nitrogen conservation via the detrital pathway could be of considerable significance. We found indications for a rather efficient reabsorption by the plant of nitrogen regenerated from seagrass leaf litter, with a meaningful role for the leaves, and postulate that increasing patch size may coincide with increasing nitrogen conservation in the system as a whole.
Horizontal and vertical complexity of attached and free‐living bacteria of the eastern Mediterranean Sea, determined by 16S rDNA and 16S rRNA fingerprints
Authors: Moeseneder Markus M. , Winter Christian. , Herndl Gerhard J.
Published: June 2010

The community structure of attached and free‐living bacteria in the Aegean Sea (eastern Mediterranean Sea) was analyzed with use of terminal‐restriction fragment length polymorphism (T‐RFLP) fingerprinting. Since the Aegean Sea is characterized by rather small temperature fluctuations between surface and deep‐water layers, it represents an ideal study site to determine the variations in the community structure of bacteria with depth, since environmental factors other than temperature are likely to determine depth zonation of bacteria. The analysis of 132 T‐RFLP electropherograms indicated pronounced differences among the attached and free‐living bacterial communities defined as operational taxonomic units (OTUs). Distinct vertical differences of attached and free‐living OTUs were found between mesopelagic waters (>200 m depth) and the upper mixed water column (~10–200 m). Attached and free‐living OTUs differed considerably throughout the water column, with only ~35% for the South Aegean and ~24% for the North Aegean of all OTUs in both free‐living and attached OTUs. Approximately 50% of attached and free‐living OTUs were present throughout the water column. Fingerprinting analysis using 16S rRNA indicated that only ~14% of the attached and ~33% of the free‐living OTUs were identical to the 16S rDNA fingerprints. The distribution of free‐living versus attached bacteria as obtained in this study suggests that even in the absence of temperature as a major selective factor, a distinct deep‐water bacterial community exists (particularly in the free‐living mode). The deep‐water free‐living bacterial community appears to be as compositionally complex as the surface water free‐living bacterial community.
Determination of pore‐water dissolved organic carbon fluxes from Mexican margin sediments
Authors: Holcombe Brook L. , Keil Richard G. , Devol Allan H.
Published: June 2010

Sediment dissolved organic carbon (DOC) fluxes were determined in the oxygen minimum zone along the north‐western Mexican margin using five different methods: in situ benthic chambers, on‐deck incubations, slicing, dialysis sampling (peepers), and sipping. For each of the five methods, replicates (n = 6–12) were made. Directly determined fluxes (whole‐core incubations and benthic chambers) and calculated fluxes (sliced and dialysis‐sampled cores) agree well (0.41 ± 0.09, 0.36 ± 0.04, 0.25 ± 0.05, and 0.25 ± 0.05 mmol C m−2 d−1, respectively). On the Mexican margin, the DOC flux was 8% of the sedimentary carbon input, suggesting that it is a significant component to the local carbon budget. Extrapolations of this flux to the total global margin suggest that shelf and slope sediments contribute 96 Tg C yr−1. The residence time of oceanic DOC based on this flux is consistent with measurements of the deep‐water DO 14 C age. Profiles were also constructed from sip‐isolated pore waters and yield consistently lower DOC profile gradients and DOC fluxes (0.06 ± 0.02 mmol C m−2 d−1). We propose that the consistently observed discrepancy between sip‐isolated profiles and other isolation techniques is a result of sampling different reservoirs of pore water present in the heterogeneous sediment matrix.
Nitrogen isotopic evidence for micronutrient control of fractional NO3− utilization in the equatorial Pacific
Authors: Altabet Mark A.
Published: June 2010

During the U.S. JGOFS EqPac program, variations in nitrogen isotopic ratio (d15N) and their control by relative NO3− drawdown were examined in detail. Near‐surface d15N data clearly conform to Rayleigh isotopic fractionation during phytoplankton utilization of NO , with a fractionation factor of about 5‰. This isotopic signal both propagates into particulate nitrogen pools and is a persistent, large‐scale characteristic of the system. Decreasing near‐surface [NO3−] with distance from the equator strongly correlates with increasing d15N in euphotic zone particulate organic matter (POM) as well as sinking particles during both Surveys 1 (El Niño) and 2 (non‐El Niño) cruises. Despite a doubling of [NO3−] accompanying relaxation of El Niño conditions, d15N values in near‐surface POM and deeply sinking particles as a function of latitude were similar for the two periods. Since d15N varies with relative nutrient drawdown and not its concentration, this parameter appears to not have varied significantly. In both cases, about 50% of upwelled NO3− was consumed in the immediate vicinity of the equator, as estimated from the d15N data. The moored sediment trap time series provided a more highly resolved temporal view of the 15N dynamics of this system. At the equator and to the south, there is little temporal variation in d15N and, hence, in relative NO3− utilization over the 1‐yr duration of the program. At 28 and 58°N, there is a large 5‰ decrease in d15N during the transition to non‐El Niño conditions in response to the northward movement of NO3− ‐rich waters, which probably reflects the intensification of the north equatorial current. Overall, % NO3− utilization at the equator remained between 40 and 60% over the observation period, despite large hydrographic and dynamical changes. This observation implies a tight control of relative NO3− utilization, consistent with iron (Fe) limitation. Since Fe is supplied in this region by upwelling, relative NO3− utilization is likely determined by the product of the ratio of Fe to NO3− in upwelled waters and the NO3− : Fe utilization ratio. Given no change in the chemistry of source waters, increases in upwelling, as observed during the transition away from El Niño, will affect surface [NO3−] new and export production, but it will not affect relative NO3− utilization. In this light, downcore d15N records in the equatorial Pacific should reflect past changes in the limitation of NO3− drawdown by Fe, perhaps through changes in equatorial undercurrent chemistry.
Differences in the persistency of the North Atlantic Oscillation signal among lakes
Authors: Gerten Dieter , Adrian Rita
Published: June 2010

Large‐scale climatic fluctuations, such as the El Niño Southern Oscillation and the North Atlantic Oscillation (NAO), are known to influence variability in abiotic site conditions and organism population dynamics in both terrestrial and aquatic ecosystems. Here we demonstrate that the influence of the NAO on lake water temperatures—one of the major factors controlling ecological processes in lakes—differs substantially among lake types of different thermal structures and mixing regimes, even under identical climatic forcing. A frequently circulating polymictic lake was found to be least influenced by the winter effects of the NAO, with an effect lasting only into early spring. In contrast, in a deep dimictic lake with stable summer stratification, the NAO signal persisted in the hypolimnion until the following winter. A shallow dimictic lake revealed an intermediate response, as weather conditions both in April and midsummer probably modified the strength and persistency of the NAO signal in the hypolimnion of that lake. Based on these results, it is to be expected that NAO effects on ecological processes vary significantly among lakes. Because the study period (1979–1998) includes a series of uncommonly warm winter and spring seasons, our findings also suggest that the influence of anticipated climate warming will vary substantially among lake types.
Atoll morphometry controls lagoon nutrient regime
Authors: Dufour Philippe , Andréfouët Serge , Charpy Loic , Garcia Nicole
Published: June 2010

Nutrient control of phytoplankton was studied in 12 atoll lagoons of contrasting morphology in the Tuamotu Archipelago in the South Pacific. In large lagoons and in small lagoons well open to the ocean, N limitation was indicated by dissolved inorganic N (DIN, NO3− + NO2− NH4+) < 0.5 mM, by DIN/P‐PO4 ratios < 3 atom atom−1, and by increased phytoplankton and bacterioplankton productivity after N enrichment. This trend shifts to P limitation for shallow, enclosed lagoons. N or P limitations are empirically predictable and explainable according to atoll‐scale morphometric factors.
Utility of radium isotopes for evaluating the input and transport of groundwater‐derived nitrogen to a Cape Cod estuary
Authors: Charette Matthew A. , Buesseler Ken O. , Andrews John E.
Published: June 2010

Because of rapid increases in population, anthropogenic sources of nitrogen have adversely impacted the water quality of coastal ponds on Cape Cod. A major source of “new” nitrogen to these estuaries is groundwater, which intercepts septic tank fields in its flow path to the coastline. Many attempts have been made to quantify this process; however, groundwater discharge is often patchy in nature and is therefore difficult to study by use of traditional techniques such as seepage meters. In Waquoit Bay, MA, we tested an approach based on radium, which is naturally enriched in aquifer fluids and has four isotopes with half‐lives ranging from 4 d to 1600 yr. Groundwater entering the bay was low in salinity and contained several orders of magnitude greater radium and dissolved inorganic nitrogen (DIN) relative to ambient bay water. Using a mass‐balance approach for radium, we calculated a submarine groundwater flux of ~37,000 m3 d−1, which compared well with aquifer recharge rates calculated from rainfall. From the DIN content of the groundwater, we estimated that ~2100 mol N d−1 was directly input to the estuary. However, this nitrogen flux was small in comparison with literature values for DIN fluxes from the heavily populated subestuaries. Furthermore, our results suggest that groundwater flux of DIN was assimilated by plant biomass during the summer but may be exported from the embayment to coastal waters during the winter months.