Search results for: Transition metal nitride coatings

Authors: Thembelihle Nkonyane, Freeman Ntuli, Edison Muzenda

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The use of un-activated bentonite, and un-activated bentonite blended with limestone for the treatment of acid mine drainage (AMD) was investigated. Batch experiments were conducted in a 5 L PVC reactor. Un-activated bentonite on its own did not effectively neutralize and remove heavy metals from AMD. The final pH obtained was below 4 and the metal removal efficiency was below 50% for all the metals when bentonite solid loadings of 1, 5 and 10% were used. With un-activated bentonite (1%) blended with 1% limestone, the final pH obtained was approximately 7 and metal removal efficiencies were greater than 60% for most of the metals. The Langmuir isotherm gave the best fit for the experimental data giving correlation coefficient (R2) very close to 1. Thus, it was concluded that un-activated bentonite blended with limestone is suitable for potential applications in removing heavy metals and neutralizing AMD.

Keywords: acid mine drainage, bentonite, limestone, heavy metal removal.

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Authors: Richard Grünes, Karel Roubik

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The article deals with technical support of intracranial single unit activity measurement. The parameters of the whole measuring set were tested in order to assure the optimal conditions of extracellular single-unit recording. Metal microelectrodes for measuring the single-unit were tested during animal experiments. From signals recorded during these experiments, requirements for the measuring set parameters were defined. The impedance parameters of the metal microelectrodes were measured. The frequency-gain and autonomous noise properties of preamplifier and amplifier were verified. The measurement and the description of the extracellular single unit activity could help in prognoses of brain tissue damage recovery.

Keywords: Measuring set, metal microelectrodes, single-unit, noise, impedance parameters, gain characteristics.

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Authors: Y. S. Tai, M. Y. Huang, H. T. Hu

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The commercial finite element program LS-DYNA was employed to evaluate the response and energy absorbing capacity of cylindrical metal tubes that are externally wrapped with composite. The effects of composite wall thickness, loading conditions and fiber ply orientation were examined. The results demonstrate that a wrapped composite can be utilized effectively to enhance the crushing characteristics and energy absorbing capacity of the tubes. Increasing the thickness of the composite increases the mean force and the specific energy absorption under both static and dynamic crushing. The ply pattern affects the energy absorption capacity and the failure mode of the metal tube and the composite material property is also significant in determining energy absorption efficiency.

Keywords: fiber-reinforced metal tubes, energy absorption, axial crushing, impact loading.

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Authors: Gulnaziya Issabayeva, Mohamed Kheireddine Aroua

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commercially produced in Malaysia granular palm shell activated carbon (PSAC) was biomodified with bacterial biomass (Bacillus subtilis) to produce a hybrid biosorbent of higher efficiency. The obtained biosorbent was evaluated in terms of adsorption capacity to remove copper and zinc metal ions from aqueous solutions. The adsorption capacity was evaluated in batch adsorption experiments where concentrations of metal ions varied from 20 to 350 mg/L. A range of pH from 3 to 6 of aqueous solutions containing metal ions was tested. Langmuir adsorption model was used to interpret the experimental data. Comparison of the adsorption data of the biomodified and original palm shell activated carbon showed higher uptake of metal ions by the hybrid biosorbent. A trend in metal ions uptake increase with the increase in the solution-s pH was observed. The surface characterization data indicated a decrease in the total surface area for the hybrid biosorbent; however the uptake of copper and zinc by it was at least equal to the original PSAC at pH 4 and 5. The highest capacity of the hybrid biosorbent was observed at pH 5 and comprised 22 mg/g and 19 mg/g for copper and zinc, respectively. The adsorption capacity at the lowest pH of 3 was significantly low. The experimental results facilitated identification of potential factors influencing the adsorption of copper and zinc onto biomodified and original palm shell activated carbon.

Keywords: Adsorption, biomodification, copper, zinc, palm shell carbon.

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Authors: Chuan-Kun Liu, Chi-Wang Li

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Simultaneous recovery of copper and DCA from simulated MEUF concentrated stream was investigated. Effects of surfactant (DCA) and metal (copper) concentrations, surfactant to metal molar ratio (S/M ratio), electroplating voltage, EDTA concentration, solution pH, and salt concentration on metal recovery and current efficiency were studied. Electric voltage of -0.5 V was shown to be optimum operation condition in terms of Cu recovery, current efficiency, and surfactant recovery. Increasing Cu recovery and current efficiency were observed with increases of Cu concentration while keeping concentration of DCA constant. However, increasing both Cu and DCA concentration while keeping S/M ratio constant at 2.5 showed detrimental effect on Cu recovery at DCA concentration higher than 15 mM. Cu recovery decreases with increasing pH while current efficiency showed an opposite trend. It is believed that conductivity is the main cause for discrepancy of Cu recovery and current efficiency observed at different pH. Finally, it was shown that EDTA had adverse effect on both Cu recovery and current efficiency while addition of NaCl salt had negative impact on current efficiency at concentration higher than 8000 mg/L.

Keywords: metal recovery, MEUF waste, surfactant, electroplating.

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Authors: K. Fraňa, S. Simon

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The objective of the paper is a numerical study of heat transfer between perforated metal plates and the surrounding air flows. Different perforation structures can nowadays be found in various industrial products. Besides improving the mechanical properties, the perforations can intensify the heat transfer as well. The heat transfer coefficient depends on a wide range of parameters such as type of perforation, size, shape, flow properties of the surrounding air etc. The paper was focused on three different perforation structures which have been investigated from the point of the view of the production in the previous studies. To determine the heat coefficients and the Nusselt numbers, the numerical simulation approach was adopted. The calculations were performed using the OpenFOAM software. The three-dimensional, unstable, turbulent and incompressible air flow around the perforated surface metal plate was considered.

Keywords: Perforations, convective heat transfers, turbulent flows, numerical simulations.

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Authors: L. Sandu, F. Topalâ, S. Porojan

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Knowledge of factors, which influence stress and its distribution, is of key importance to the successful production of durable restorations. One of this is the marginal geometry. The objective of this study was to evaluate, by finite element analysis (FEA), the influence of different marginal designs on the stress distribution in teeth prepared for cast metal crowns. Five margin designs were taken into consideration: shoulderless, chamfer, shoulder, sloped shoulder and shoulder with bevel. For each kind of preparation three dimensional finite element analyses were initiated. Maximal equivalent stresses were calculated and stress patterns were represented in order to compare the marginal designs. Within the limitation of this study, the shoulder and beveled shoulder margin preparations of the teeth are preferred for cast metal crowns from biomechanical point of view.

Keywords: finite element, marginal geometry, metal crown

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Authors: K. Krishnaprasad, Raghu V. Prakash

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Constant amplitude fatigue crack growth (FCG) tests were performed on dissimilar metal welded plates of Type 316L Stainless Steel (SS) and IS 2062 Grade A Carbon steel (CS). The plates were welded by TIG welding using SS E309 as electrode. FCG tests were carried on the Side Edge Notch Tension (SENT) specimens of 5 mm thickness, with crack initiator (notch) at base metal region (BM), weld metal region (WM) and heat affected zones (HAZ). The tests were performed at a test frequency of 10 Hz and at load ratios (R) of 0.1 & 0.6. FCG rate was found to increase with stress ratio for weld metals and base metals, where as in case of HAZ, FCG rates were almost equal at high ΔK. FCG rate of HAZ of stainless steel was found to be lowest at low and high ΔK. At intermediate ΔK, WM showed the lowest FCG rate. CS showed higher crack growth rate at all ΔK. However, the scatter band of data was found to be narrow. Fracture toughness (Kc) was found to vary in different locations of weldments. Kc was found lowest for the weldment and highest for HAZ of stainless steel. A novel method of characterizing the FCG behavior using an Infrared thermography (IRT) camera was attempted. By monitoring the temperature rise at the fast moving crack tip region, the amount of plastic deformation was estimated.

Keywords: Dissimilar metal weld, Fatigue Crack Growth, fracture toughness, Infrared thermography.

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Authors: B.Tavakoly Sany, A.H .Sulaiman, GH. Monazami, A. Salleh

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Eight heavy metals (Cu, Cr, Zn, Hg, Pb, Cd, Ni and As) were analyzed in sediment samples in the dry and wet seasons from November 2009 to October 2010 in West Port of Peninsular Malaysia. The heavy metal concentrations (mg/kg dry weight) were ranged from 23.4 to 98.3 for Zn, 22.3 to 80 for Pb, 7.4 to 27.6 Cu, 0.244 to 3.53 for Cd, 7.2 to 22.2 for Ni, 20.2 to 162 for As, 0.11 to 0.409 for Hg and 11.5 to 61.5 for Cr. Metals concentrations in dry season were higher than the rainy season except in cupper and chromium. Analysis of variance with Statistical Analysis System (SAS) shows that the mean concentration of metals in the two seasons (α level=0.05) are not significantly different which shows that the metals were held firmly in the matrix of sediment. Also there are significant differences between control point station with other stations. According to the Interim Sediment Quality guidelines (ISQG), the metal concentrations are moderately polluted, except in arsenic which shows the highest level of pollution.

Keywords: Heavy metals, sediment quality guidelines, west port.

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Authors: Yunyoung Nam, Junghun Ryu, Yoo-Joo Choi, We-Duke Cho

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This paper presents a novel approach for representing the spatio-temporal topology of the camera network with overlapping and non-overlapping fields of view (FOVs). The topology is determined by tracking moving objects and establishing object correspondence across multiple cameras. To track people successfully in multiple camera views, we used the Merge-Split (MS) approach for object occlusion in a single camera and the grid-based approach for extracting the accurate object feature. In addition, we considered the appearance of people and the transition time between entry and exit zones for tracking objects across blind regions of multiple cameras with non-overlapping FOVs. The main contribution of this paper is to estimate transition times between various entry and exit zones, and to graphically represent the camera topology as an undirected weighted graph using the transition probabilities.

Keywords: Surveillance, multiple camera, people tracking, topology.

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Authors: Keiji Komatsu, Hayato Maruyama, Ariyuki Kato, Atsushi Nakamura, Shigeo Ohshio, Hiroki Akasaka, Hidetoshi Saitoh

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Violet Sr–Al–O:Eu2+ phosphor particles were synthesized from a metal–ethylenediaminetetraacetic acid (EDTA) solution of Sr, Al, Eu, and particulate alumina via spray drying and sintering in a reducing atmosphere. The crystal structures and emission properties at 85–300 K were investigated. The composition of the violet Sr–Al–O:Eu2+ phosphor particles was determined from various Sr–Al–O:Eu2+ phosphors by their emission properties’ dependence on temperature. The highly crystalline SrAl12O19:Eu2+ emission phases were confirmed by their crystallite sizes and the activation energies for the 4f5d–8S7/2 transition of the Eu2+ ion. These results showed that the material identification for the violet Sr–Al–O:Eu2+ phosphor was accomplished by the low-temperature luminescence measurements.

Keywords: Low temperature luminescence spectroscopy, Material Identification, Strontium aluminates phosphor.

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Authors: Y. Liu, M. K. Bera, L. M. Kyaw, G. Q. Lo, E. F. Chor

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The electrical and structural properties of Hf/Al/Ni/Au (20/100/25/50 nm) ohmic contact to n-GaN are reported in this study. Specific contact resistivities of Hf/Al/Ni/Au based contacts have been investigated as a function of annealing temperature and achieve the lowest value of 1.09´10-6 Ω·cm2 after annealing at 650 oC in vacuum. A detailed mechanism of ohmic contact formation is discussed. By using different chemical analyses, it is anticipated that the formation of Hf-Al-N alloy might be responsible to form low temperature ohmic contacts for the Hf-based scheme to n-GaN.

Keywords: Gallium nitride, ohmic contact, Hafnium

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Authors: J. Kumchai, J. Z. Huang, C. Y. Lee, F. C. Chen, S. W. Chin

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Cabbage seedlings grown in vitro were exposed to excess levels of heavy metals, including Cd, Mo, and Zn. High metal levels affected plant growth at cotyledonary stage. Seedlings under Cd, Mo, and Zn treatments could not produce root hairs and true leaves. Under stress conditions, seedlings accumulated a higher amount of anthocyanins in their cotyledons than those in the control. The pigments isolated from Cd and Zn stressed seedling cotyledons appeared as pink, while under Mo stress, was dark pink or purple. Moreover, excess Mo stress increased antioxidant enzyme activities of APX, CAT, SOD. These results suggest that, under excess Mo stress, the induced antioxidant enzyme activity of cabbage seedlings may function as a protective mechanism to shield the plants from toxicity and exacerbated growth.

Keywords: Anthocyanin, antioxidant enzyme activity, heavy metal, growth inhibition.

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Authors: Chinsuk Hong

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This paper investigates the characteristics of wall pressure fluctuations in naturally developing boundary layer flows on axisymmetric bodies experimentally. The axisymmetric body has a modified ellipsoidal blunt nose. Flush-mounted microphones are used to measure the wall pressure fluctuations in the boundary layer flow over the body. The measurements are performed in a low noise wind tunnel. It is found that the correlation between the flow regime and the characteristics of the pressure fluctuations is distinct. The process from small fluctuation in laminar flow to large fluctuation in turbulent flow is investigated. Tollmien-Schlichting wave (T-S wave) is found to generate and develop in transition. Because of the T-S wave, the wall pressure fluctuations in the transition region are higher than those in the turbulent boundary layer.

Keywords: Wall Pressure Fluctuation, Boundary Layer Flow, Transition, Turbulent Flow, Axisymmetric Body, Flow Noise.

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Authors: Samera Salimpour Abkenar

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In traditional dyeing of natural fibers with natural dyes, metal salts are commonly used to increase color stability. This method always carries the risk of environmental pollution (contamination of arable soils and fresh groundwater) due to the release of dyeing effluents containing large amounts of metal. Therefore, researchers are always looking for new methods to obtain a green dyeing system. In this research, the use of the enzymatic dyeing method to prevent environmental pollution with metals and reduce production costs has been proposed. After degumming and bleaching, raw silk fabrics were dyed with natural dyes (Madder and Sumac) by three methods (pre-mordanting with a metal salt, one-step enzymatic dyeing, and two-step enzymatic dyeing). Results show that silk dyed with natural dyes by the enzymatic method has higher color strength and colorfastness than the pretreated with a metal salt. Also, the amount of remained dyes in the dyeing wastewater is significantly reduced by the enzymatic method. It is found that the enzymatic dyeing method leads to improvement of dye absorption, color strength, soft hand, no change in color shade, low production costs (due to low dyeing temperature), and a significant reduction in environmental pollution.

Keywords: Eco-friendly, natural dyes, silk, traditional dyeing.

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Authors: Cheng-Chieh Chiang, Yi-Chia Chan, Greg C. Lee

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This paper proposes a video-based framework for face recognition to identify which faces appear in a video sequence. Our basic idea is like a tracking task - to track a selection of person candidates over time according to the observing visual features of face images in video frames. Hence, we employ the state-space model to formulate video-based face recognition by dividing this problem into two parts: the likelihood and the transition measures. The likelihood measure is to recognize whose face is currently being observed in video frames, for which two-dimensional linear discriminant analysis is employed. The transition measure estimates the probability of changing from an incorrect recognition at the previous stage to the correct person at the current stage. Moreover, extra nodes associated with head nodes are incorporated into our proposed state-space model. The experimental results are also provided to demonstrate the robustness and efficiency of our proposed approach.

Keywords: 2DLDA, face recognition, state-space model, likelihood measure, transition measure.

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Authors: Javaid Butt, Habtom Mebrahtu, Hassan Shirvani

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The paper presents an additive manufacturing process for the production of metal and composite parts. It is termed as composite metal foil manufacturing and is a combination of laminated object manufacturing and brazing techniques. The process has been described in detail and is being used to produce dissimilar aluminum to copper foil single lap joints. A three dimensional finite element model has been developed to study the thermo-mechanical characteristics of the dissimilar Al/Cu single lap joint. The effects of thermal stress and strain have been analyzed by carrying out transient thermal analysis on the heated plates used to join the two 0.1mm thin metal foils. Tensile test has been carried out on the foils before joining and after the single Al/Cu lap joints are made, they are subjected to tensile lap-shear test to analyze the effect of heat on the foils. The analyses are designed to assess the mechanical integrity of the foils after the brazing process and understand whether or not the heat treatment has an effect on the fracture modes of the produced specimens.

Keywords: Brazing, Laminated Object Manufacturing, Tensile Lap-Shear Test, Thermo-Mechanical Analysis.

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Authors: John Kabuba, Hilary Rutto

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Ion exchange is one of the methods used to remove heavy metal such as copper and cobalt from wastewaters. Parameters affecting the ion-exchange of copper and cobalt aqueous solutions using clinoptilolite are the objectives of this study. Synthetic solutions were prepared with the concentration of 0.02M, 0.06M and 0.1M. The cobalt solution was maintained to 0.02M while varying the copper solution to the above stated concentrations. The clinoptilolite was activated with HCl and H₂SO₄ for removal efficiency. The pHs of the solutions were found to be acidic hence enhancing the copper and cobalt removal. The natural clinoptilolite performance was also found to be lower compared to the HCl and H₂SO₄ activated one for the copper removal ranging from 68% to 78% of Cu²⁺ uptake with the natural clinoptilolite to 66% to 51% with HCl and H₂SO₄ respectively. It was found that the activated clinoptilolite removed more copper and cobalt than the natural one and found that the electronegativity of the metal plays a role in the metal removal and the clinoptilolite selectivity.

Keywords: Clinoptilolite, cobalt and copper, Ion-exchange, mass dosage, pH.

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Authors: M. E. Turan, H. Zengin, E. Cevik, Y. Sun, Y. Turen, H. Ahlatci

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In this study, the effects of B₄C and SiC particle reinforcements on wear properties of magnesium matrix metal composites produced by pressure infiltration method were investigated. AZ91 (9%Al-1%Zn) magnesium alloy was used as a matrix. AZ91 magnesium alloy was melted under an argon atmosphere. The melt was infiltrated to the particles with an appropriate pressure. Wear tests, hardness tests were performed respectively. Microstructure characterizations were examined by light optical (LOM) and scanning electron microscope (SEM). The results showed that uniform particle distributions were achieved in both B₄C and SiC reinforced composites. Wear behaviors of magnesium matrix metal composites changed as a function of type of particles. SiC reinforced composite has better wear performance and higher hardness than B₄C reinforced composite.

Keywords: Magnesium matrix composite, pressure infiltration, SEM, wear.

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Authors: Meena Marafi, Mohan S. Rana

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Catalysts play an important role in producing valuable fuel products in petroleum refining; but, due to feedstock’s impurities catalyst gets deactivated with carbon and metal deposition. The disposal of spent catalyst falls under the category of hazardous industrial waste that requires strict agreement with environmental regulations. The spent hydroprocessing catalyst contains Mo, V and Ni at high concentrations that have been found to be economically significant for recovery. Metal recovery process includes deoiling, decoking, grinding, dissolving and treatment with complexing leaching agent such as ethylene diamine tetra acetic acid (EDTA). The process conditions have been optimized as a function of time, temperature and EDTA concentration in presence of ultrasonic agitation. The results indicated that optimum condition established through this approach could recover 97%, 94% and 95% of the extracted Mo, V and Ni, respectively, while 95% EDTA was recovered after acid treatment.

Keywords: Spent catalyst, deactivation, hydrotreating, spent catalyst.

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Authors: C. A. C. Castro, D. C. Urashima, E. P. Silva, P. M. L.Silva

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Since 1920, the industry has almost completely changed the rivets production techniques for the manufacture of permanent welding join production of structures and manufacture of other products. The welding arc is the process more widely used in industries. This is accomplished by the heat of an electric arc which melts the base metal while the molten metal droplets are transferred through the arc to the welding pool, protected from the atmosphere by a gas curtain. The GMAW (Gas metal arc welding) process is influenced by variables such as: current, polarity, welding speed, electrode: extension, position, moving direction; type of joint, welder's ability, among others. It is remarkable that the knowledge and control of these variables are essential for obtaining satisfactory quality welds, knowing that are interconnected so that changes in one of them requiring changes in one or more of the other to produce the desired results. The optimum values are affected by the type of base metal, the electrode composition, the welding position and the quality requirements. Thus, this paper proposes a new methodology, adding the variable vibration through a mechanism developed for GMAW welding, in order to improve the mechanical and metallurgical properties which does not affect the ability of the welder and enables repeatability of the welds made. For confirmation metallographic analysis and mechanical tests were made.

Keywords: HAZ, GMAW, vibration, welding.

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Authors: Ching M. Hsu, Rong F. Huang, Michael E. Loretero

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Shear-layer instabilities of a pulsed stack-issued transverse jet were studied experimentally in a wind tunnel. Jet pulsations were induced by means of acoustic excitation. Streak pictures of the smoke-flow patterns illuminated by the laser-light sheet in the median plane were recorded with a high-speed digital camera. Instantaneous velocities of the shear-layer instabilities in the flow were digitized by a hot-wire anemometer. By analyzing the streak pictures of the smoke-flow visualization, three characteristic flow modes, synchronized flapping jet, transition, and synchronized shear-layer vortices, are identified in the shear layer of the pulsed stack-issued transverse jet at various excitation Strouhal numbers. The shear-layer instabilities of the pulsed stack-issued transverse jet are synchronized by acoustic excitation except for transition mode. In transition flow mode, the shear-layer vortices would exhibit a frequency that would be twice as great as the acoustic excitation frequency.

Keywords: Acoustic excitation, jet in crossflow, shear-layer instability.

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Authors: Hidetoshi Konno, Akio Suzuki

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The paper presented a transient population dynamics of phase singularities in 2D Beeler-Reuter model. Two stochastic modelings are examined: (i) the Master equation approach with the transition rate (i.e., λ(n, t) = λ(t)n and μ(n, t) = μ(t)n) and (ii) the nonlinear Langevin equation approach with a multiplicative noise. The exact general solution of the Master equation with arbitrary time-dependent transition rate is given. Then, the exact solution of the mean field equation for the nonlinear Langevin equation is also given. It is demonstrated that transient population dynamics is successfully identified by the generalized Logistic equation with fractional higher order nonlinear term. It is also demonstrated the necessity of introducing time-dependent transition rate in the master equation approach to incorporate the effect of nonlinearity.

Keywords: Transient population dynamics, Phase singularity, Birth-death process, Non-stationary Master equation, nonlinear Langevin equation, generalized Logistic equation.

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Authors: Dejan Tanikić, Jelena Đoković, Saša Kalinović, Miodrag Manić, Saša Ranđelović

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This paper deals with measuring and modelling of the quality of the machined surface of the metal machining process. The average surface roughness (R_a) which represents the quality of the machined part was measured during the dry turning of the AISI 4140 steel. A large number of factors with the unknown relations among them influences this parameter, and that is why mathematical modelling is extremely complicated. Different values of cutting speed, feed rate, depth of cut (cutting regime) and workpiece hardness causes different surface roughness values. Modelling with soft computing techniques may be very useful in such cases. This paper presents the usage of the fuzzy logic-based system for determining metal machining process parameter in order to find the proper values of cutting regimes.

Keywords: Metal machining, surface roughness, fuzzy logic, process modelling.

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Authors: M. Battira, R. Bessaih

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We numerically study the three-dimensional magnetohydrodynamics (MHD) stability of oscillatory natural convection flow in a rectangular cavity, with free top surface, filled with a liquid metal, having an aspect ratio equal to A=L/H=5, and subjected to a transversal temperature gradient and a uniform magnetic field oriented in x and z directions. The finite volume method was used in order to solve the equations of continuity, momentum, energy, and potential. The stability diagram obtained in this study highlights the dependence of the critical value of the Grashof number Grcrit , with the increase of the Hartmann number Ha for two orientations of the magnetic field. This study confirms the possibility of stabilization of a liquid metal flow in natural convection by application of a magnetic field and shows that the flow stability is more important when the direction of magnetic field is longitudinal than when the direction is transversal.

Keywords: Natural convection, Magnetic field, Oscillatory, Cavity, Liquid metal.

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Authors: Reginald D. Smith

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The dynamics of User Datagram Protocol (UDP) traffic over Ethernet between two computers are analyzed using nonlinear dynamics which shows that there are two clear regimes in the data flow: free flow and saturated. The two most important variables affecting this are the packet size and packet flow rate. However, this transition is due to a transcritical bifurcation rather than phase transition in models such as in vehicle traffic or theorized large-scale computer network congestion. It is hoped this model will help lay the groundwork for further research on the dynamics of networks, especially computer networks.

Keywords: congestion, packet flow, Internet, traffic dynamics, transcritical bifurcation

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Authors: M. Cheraghi, B. Lorestani, N. Yousefi

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Contamination of heavy metals represents one of the most pressing threats to water and soil resources as well as human health. Phytoremediation can be potentially used to remediate metalcontaminated sites. A major step towards the development of phytoremediation of heavy metal impacted soils is the discovery of the heavy metal hyperaccumulation in plants. In this study, the several established criteria to define a hyperaccumulator plant were applied. The case study was represented by a mining area in Hamedan province in the central west part of Iran. Obtained results showed that the most of sampled species were able to grow on heavily metal-contaminated soils and also were able to accumulate extraordinarily high concentrations of some metals such as Zn, Mn, Cu, Pb and Fe. Using the most common criteria, Euphorbia macroclada and Centaurea virgata can be classified as hyperaccumulators of some measured heavy metals and, therefore, they have suitable potential for phytoremediation of contaminated soils.

Keywords: Enrichment factor, Heavy metals, Hyperaccumulator, Phytoremediation, Translocation factor

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Authors: Alaaddin Cerit, Suheyla Kocaman, Ulku Soydal

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During the past two decades, photoinitiated polymerization has been attracting a great interest in terms of scientific and industrial activity. The wide recognition of UV treatment in the polymer industry results not only from its many practical applications but also from its advantage for low-cost processes. Unlike most thermal curing systems, radiation-curable systems can polymerize at room temperature without additional heat, and the curing is completed in a very short time. The advantage of cationic UV technology is that post-cure can continue in the ‘dark’ after radiation. In this study, bio-based acrylated epoxidized soybean oil (AESO) was cured with UV radiation using radicalic photoinitiator Irgacure 184. Triarylsulphonium hexafluoroantimonate was used as cationic photoinitiator for curing of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate. The effect of curing time and the amount of initiators on the curing degree and thermal properties were investigated. The thermal properties of the coating were analyzed after crosslinking UV irradiation. The level of crosslinking in the coating was evaluated by FTIR analysis. Cationic UV-cured coatings demonstrated excellent adhesion and corrosion resistance properties. Therefore, our study holds a great potential with its simple and low-cost applications.

Keywords: Acrylated epoxidized soybean oil, epoxy carboxylate, thermal properties, UV-curing.

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Authors: Werner Sandmann, Verena Wolf

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Stochastic models of biological networks are well established in systems biology, where the computational treatment of such models is often focused on the solution of the so-called chemical master equation via stochastic simulation algorithms. In contrast to this, the development of storage-efficient model representations that are directly suitable for computer implementation has received significantly less attention. Instead, a model is usually described in terms of a stochastic process or a "higher-level paradigm" with graphical representation such as e.g. a stochastic Petri net. A serious problem then arises due to the exponential growth of the model-s state space which is in fact a main reason for the popularity of stochastic simulation since simulation suffers less from the state space explosion than non-simulative numerical solution techniques. In this paper we present transition class models for the representation of biological network models, a compact mathematical formalism that circumvents state space explosion. Transition class models can also serve as an interface between different higher level modeling paradigms, stochastic processes and the implementation coded in a programming language. Besides, the compact model representation provides the opportunity to apply non-simulative solution techniques thereby preserving the possible use of stochastic simulation. Illustrative examples of transition class representations are given for an enzyme-catalyzed substrate conversion and a part of the bacteriophage λ lysis/lysogeny pathway.

Keywords: Computational Modeling, Biological Networks, Stochastic Models, Markov Chains, Transition Class Models.

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Authors: M. Areekijseree, M. Pumipaiboon, S. Nuamsukon, K. Kittiwattanawong, C. Thongchai, S. Sikiwat, T. Chuen-Im

Abstract:

There are few studies on eggshell of leatherback turtle which is endangered species in Thailand. This study was focusing on the ultrastructure and elemental composition of leatherback turtle eggshells collected from Andaman Sea Shore, Thailand during the nesting season using scanning electron microscope (SEM). Three eggshell layers of leatherback turtle; the outer cuticle layer or calcareous layer, the middle layer or middle multistrata layer and the inner fibrous layer were recognized. The outer calcareous layer was thick and porosity which consisted of loose nodular units of various crystal shapes and sizes. The loose attachment between these units resulted in numerous spaces and openings. The middle layer was compact thick with several multistrata and contained numerous openings connecting to both outer cuticle layer and inner fibrous layer. The inner fibrous layer was compact and thin, and composed of numerous reticular fibers. Energy dispersive X-ray microanalysis detector revealed energy spectrum of X-rays character emitted from all elements on each layer. The percentages of all elements were found in the following order: carbon (C) > oxygen (O) > calcium (Ca) > sulfur (S) > potassium (K) > aluminum (Al) > iodine (I) > silicon (Si) > chlorine (Cl) > sodium (Na) > fluorine (F) > phosphorus (P) > magnesium (Mg). Each layer consisted of high percentage of CaCO3 (approximately 98%) implying that it was essential for turtle embryonic development. A significant difference was found in the percentages of Ca and Mo in the 3layers. Moreover, transition metal, metal and toxic non-metal contaminations were found in leatherback turtle eggshell samples. These were palladium (Pd), molybdenum (Mo), copper (Cu), aluminum (Al), lead (Pb), and bromine (Br). The contamination elements were seen in the outer layers except for Mo. All elements were readily observed and mapped using Smiling program. X-ray images which mapped the location of all elements were showed. Calcium containing in the eggshell appeared in high contents and was widely distributing in clusters of the outer cuticle layer to form CaCO3 structure. Moreover, the accumulation of Na and Cl was observed to form NaCl which was widely distributing in 3 eggshell layers. The results from this study would be valuable on assessing the emergent success in this endangered species.

Keywords: Leatherback turtle (Dermochelys coriacea), SEM (SEI/EDX), turtle eggshell.

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