Electrodeposition of aluminium and aluminium-copper alloys from a room temperature ionic liquid electrolyte containing aluminium chloride and triethylamine hydrochloride

The electrodeposition of A1 and A1-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing A1C13-EtaNHC1 was studied. The electrochemical behavior of the electrolyte and the mechanism of deposition were investigated through cyclic voltammetry （CV）, and the properties of deposits obtained were assessed by scanning electron microscopy with energy dispersive X-ray spectroscopy （SEM-EDS） and X-ray diffraction （XRD）. A1 of 70μm in thickness and an A1-Cu alloy of 30μm in thickness with 8at% copper were deposited from the electrolyte. SEM images of the deposits indicate that the A1 deposit was smooth and uniform, whereas the Al-Cu deposit was nodular. The average crystalline size, as determined by XRD patterns, was found to be （30±5） and （29±5） nm, respectively, for A1 and A1-Cu alloys. Potentiodynamic polarization （Tafel plots） and electrochemical impedance spectroscopic （EIS） measurements showed that Al-Cu alloys are more corrosion resistant than Al.

Studies on the effect of weld defect on the fatigue behavior of welded structures

Structural integrity isstated as the science and technology of margin between safety and disaster. Systematic prediction of structural integrity of critical structures such ascombustion chambers,pressure vessels,nuclear reactor components,boilers etc.,ensures the human safety,environmental protection,and the economical considerations.The present work aims at prediction of fatigue behaviour of symmetric structures like pressure vessels in the presence of common welding defects such as lack of fusion( LOF),lack of penetration( LOP) and porosity.A ring type specimen which replicates the stress pattern in thepressure vessel is considered for the study of severity of weld imperfections. Initial dimensions of weld defects are arrived by performing NDT inspection.Crack growth analysis is carried out to determine the remaining life of the welded joint with defects.

Performance evaluation of nickel as anode catalyst for DMFC in acidic and alkaline medium

Direct methanol fuel cell(DMFC)research is highly focused due to its high energy density,portability and inexpensive.In the present study conventional platinum catalyst used for methanol oxidation is being replaced with nickel catalyst supported over nickel mesh.The electrode is synthesized by single step electro deposition technique.Synthesized electrode was characterized by SEM,EDAX and AFM techniques to know the surface morphology,composition and thickness of the catalyst respectively.The electro catalytic behavior of the nickel for methanol oxidation was evaluated using cyclic voltammetry technique.As the DMFC is compatible with both the acidic and alkaline electrolytes the working of the nickel mesh electrode is analyzed in both media.The results showed maximum current density of 0.025 and 0.030 A/cm2 in alkaline and acidic medium respectively with less potential around 0.4 and 0.2 V.The other parameters such as varying the concentration of methanol,electrolyte medium,scan rate and thickness of the catalytic layer were analyzed and optimized.

Antioxidant and hepatoprotective effects of Hypsizygus ulmarius polysaccharide on alcoholic liver injury in rats

Hypsizygus ulmarius polysaccharide(HUP)is a water-soluble polysaccharide obtained by hot water extraction,followed by precipitation and deproteinization.The characteristics of HUP,antioxidant activity and liver protection against alcohol-induced liver damage were studied.Structural characteristics indicate that the HUP is a pyran-type polysaccharide with a molecular weight of 2076 Da.In antioxidant scavenging assay,HUP showed moderate DMPD radical scavenging activity,cupric ion reducing antioxidant capacity and inhibitory effect against lipid peroxidation in a dose-dependent manner.Regarding in vivo hepatoprotective activity,compared with the ethanol induction group,pre-treatment of low and high doses of HUP signifi cantly reduced the behaviours of serum enzymes,lowered the levels of hepatic oxidative stress markers,restored the levels of biochemical constituents,enhanced the levels of liver and serum enzymatic antioxidants and non-enzymatic antioxidants,and improved the serum lipid levels of alcohol-intoxicated rats.The hepatoprotective effect of HUP was comparable to positive control silymarin.Besides,HUP pre-treatment signifi cantly normalized the histopathological changes induced by ethanol.The results indicate that HUP could be used as a functional food and may protect the biological system from oxidative stress through its antioxidant activity,thus having a signifi cant protective effect on acute alcoholic liver injury.

Design of area and power efficient Radix-4 DIT FFT butterfly unit using floating point fused arithmetic

In this work, power efficient butterfly unit based FFT architecture is presented. The butterfly unit is designed using floating-point fused arithmetic units. The fused arithmetic units include two-term dot product unit and add-subtract unit. In these arithmetic units, operations are performed over complex data values. A modified fused floating-point two-term dot product and an enhanced model for the Radix-4 FFT butterfly unit are proposed. The modified fused two-term dot product is designed using Radix-16 booth multiplier. Radix-16 booth multiplier will reduce the switching activities compared to Radix-8 booth multiplier in existing system and also will reduce the area required. The proposed architecture is implemented efficiently for Radix-4 decimation in time(DIT) FFT butterfly with the two floating-point fused arithmetic units. The proposed enhanced architecture is synthesized, implemented, placed and routed on a FPGA device using Xilinx ISE tool. It is observed that the Radix-4 DIT fused floating-point FFT butterfly requires 50.17% less space and 12.16% reduced power compared to the existing methods and the proposed enhanced model requires 49.82% less space on the FPGA device compared to the proposed design. Also, reduced power consumption is addressed by utilizing the reusability technique, which results in 11.42% of power reduction of the enhanced model compared to the proposed design.

FEM based Electromagnetic Signature Analysis of Winding Inter-turn Short-Circuit Fault in Inverter fed Induction Motor

The intent of this paper is to analyze the electromagnetic signature of stator winding inter-turn short-circuit fault in a closed loop speed controlled Induction Motor(IM)employing Finite Element Method.Stator winding short-circuit nearly covers 21%of faults in IM.Diagnosing the inter-turn fault at an incipient stage is one of the challenging task in the area of fault detection of IM to prevent crucial damages in industrial applications.Also detecting the faults in inverter fed IM under variable speed applications under varying load is one of the major issues in industrial drives.As the signatures of electromagnetic field contains the entire data in association with the location of rotor,stator and mechanical parts of the motor,a regular monitoring of fields in the airgap can be used to diagnose the inter-turn fault in the stator winding of IM.In this direction,an IM is modeled with several inter-turn fault severities like 30 turns,15 turns,5 turns&1 turn short using ANSYS Maxwell FEA tool and coupled with ANSYS Simplorer for loading arrangements.The PWM inverter with closed loop speed controlled strategy is implemented in Matlab Simulink and co-simulated with ANSYS Simplorer to integrate all the components in one common simulation platform environment for accurate design&analysis for realistic simulation.Several electromagnetic variables like flux density,flux lines and airgap flux density distribution over the machine are analyzed.The spatial FFT spectrum of radial component of flux density in the airgap contains the information related to the diagnosis of inter-turn fault at the incipient stage.

Optimization of wear parameters of binary Al-25Zn and Al-3Cu alloys using design of experiments

Zinc-aluminum alloys have been used as bearing materials in the past. In recent years, binary Al-Zn alloys and Al-Zn-Cu alloys are being used as an alternative to the Zn-Al alloys for bearing applications. In this study, both binary Al-25 Zn and Al-3 Cu were prepared using stir casting process. Homogenization of the as-cast alloys was performed at 350oC for 8 h and then, the alloys were furnace-cooled to 50oC. The homogenization led to the removal of the dendritic structure of the as-cast alloys. After homogenization, wear parameters optimization was carried out using Taguchi technique. For this purpose, L9 orthogonal array was selected, and the control parameters selected are load, velocity, and sliding distance. The optimum parametric condition was obtained using signal-to-noise(S/N) ratio analysis, and specific wear rate(SWR) is the selected response. The "smaller-the-better" is the goal of the experiment for S/N ratio analysis. After the optimization, confirmation tests were carried out using analysis of variance(ANOVA) from the developed regression equation. Finally, wear mechanism studies were conducted using scanning electron microscopy(SEM) and energy-dispersive X-ray spectroscopy(EDX) images.

Pulsatile blood flow in large arteries:comparative study of Burton's and McDonald's models

To get a clear picture of the pulsatile nature of blood flow and its role in the pathogenesis of atherosclerosis, a comparative study of blood flow in large arteries is carried out using the two widely used models, McDonald＇s and Burton＇s models, for the pressure gradient. For both models, the blood velocity in the lumen is obtained analytically. Elaborate investigations on the wall shear stress （WSS） and oscillatory shear index （OSI） are carried out. The results are in good agreement with the available data in the literature. The superiority of McDonald＇s model in capturing the pulsatile nature of blood flow, especially the OSI, is highlighted. The present investigation supports the hypothesis that not only WSS but also OSI are the essential features determining the pathogenesis of atherosclerosis. Finally, by reviewing the limitations of the present investigation, the possibility of improvement is explored.

Tribological Behaviour of Aluminium/Alumina/Graphite Hybrid Metal Matrix Composite Using Taguchi’s Techniques

Tribological behaviour of aluminium alloy (Al-Si10Mg) reinforced with alumina (9%) and graphite (3%) fabricated by stir casting process was investigated. The wear and frictional properties of the hybrid metal matrix composites was studied by performing dry sliding wear test using a pin-on-disc wear tester. Experiments were conducted based on the plan of experiments generated through Taguchi’s technique. A L27 Orthogonal array was selected for analysis of the data. Investigation to find the influence of applied load, sliding speed and sliding distance on wear rate, as well as the coefficient of friction during wearing process was carried out using ANOVA and regression equations for each response were developed. Objective of the model was chosen as ‘smaller the better’ characteristics to analyse the dry sliding wear resistance. Results show that sliding distance has the highest influence followed by load and sliding speed. Finally, confirmation tests were carried out to verify the experimental results and Scanning Electron Microscopic studies were done on the wear surfaces.

Poly caprolactone/titanium dioxide nanofiber coating on AM50 alloy for biomedical application

Poly caprolactone(PCL)and Poly caprolactone/TiO_(2)(PCL/TiO_(2))composite nanofiber with different weight percentage compositions(2 wt%,4 wt%and 6 wt%)of TiO_(2)were prepared and coated over AM50 alloy using electrospinning technique.The surface morphology and elemental composition result confirms that the PCL/TiO_(2)composite nanofiber fiber were successfully electrospun on the surface of AM50 alloy.The degradation behavior of PCL and PCL/6 wt%TiO_(2)coated AM50 alloy was studied by immersing in Simulated Body Fluid(SBF)solution.The electrochemical and cell proliferation studies reveals that the cellular behavior of PCL and PCL/6 wt%TiO_(2)composite nanofiber exhibited good support for cell proliferation with enhanced corrosion resistance of AM50 alloy in SBF solution.

Effect of reinforcement content on the adhesive wear behavior of Cu10Sn5Ni/Si3N4 composites produced by stir casting

The main objective of this paper was to fabricate CuSnNi alloy and its composites reinforced with various contents of SiNparticles(5wt%, 10wt%, and 15wt%) and to investigate their dry sliding wear behavior using a pin-on-disk tribometer. Microstructural examinations of the specimens revealed a uniform dispersion of SiNparticles in the copper matrix. Wear experiments were performed for all combinations of parameters, such as load(10, 20, and 30 N), sliding distance(500, 1000, and 1500 m), and sliding velocity(1, 2, and 3 m/s), for the alloy and the composites. The results revealed that wear rate increased with increasing load and increasing sliding distance, whereas the wear rate decreased and then increased with increasing sliding velocity. The primary wear mechanism encountered at low loads was mild adhesive wear, whereas that at high loads was severe delamination wear. An oxide layer was formed at low velocities, whereas a combination of shear and plastic deformation occurred at high velocities. The mechanism at short sliding distances was ploughing action of SiNparticles, which act as protrusions; by contrast, at long sliding distances, direct metal–metal contact occurred. Among the investigated samples, the Cu/10wt% SiNcomposite exhibited the best wear resistance at a load of 10 N, a velocity of 2 m/s, and a sliding distance of 500 m.

Nonlinear dynamics and performance analysis of modified snap-through vibration energy harvester with time-varying potential function

Vibration energy harvesting has emerged as a promising method to harvest energy for small-scale applications.Enhancing the performance of a vibration energy harvester(VEH)incorporating nonlinear techniques,for example,the snap-through VEH with geometric non-linearity,has gained attention in recent years.A conventional snap-through VEH is a bi-stable system with a time-invariant potential function,which was investigated extensively in the past.In this work,a modified snap-through VEH with a time-varying potential function subject to harmonic and random base excitations is investigated.Modified snap-through VEHs,such as the one considered in this study,are used in wave energy harvesters.However,the studies on their dynamics and energy harvesting under harmonic and random excitations are limited.The dynamics of the modified snap-through VEH is represented by a system of differential algebraic equations(DAEs),and the numerical schemes are proposed for its solutions.Under a harmonic excitation,the system exhibits periodic and chaotic motions,and the energy harvesting is superior compared with the conventional counterpart.The dynamics under a random excitation is investigated by the moment differential method and the numerical scheme based on the modified Euler-Maruyama method.The Fokker-Planck equation representing the dynamics is derived,and the marginal and joint probability density functions(PDFs)are obtained by the Monte Carlo simulation.The study shows that the modified snap-through oscillator based VEH performs better under both harmonic and random excitations.The dynamics of the system under stochastic resonance(SR)is investigated,and performance enhancement is observed.The results from this study will help in the development of adaptive VEH techniques in the future.

Influence of carbide ceramic reinforcements in improving tribological properties of A333 graded hybrid composites

Aluminium hybrid functionally graded metal matrix composites(FGMMCs),meet growing demands for supreme tribo-mechanical performance in automotive and aviation industry.This research experimentally compares the influence of carbide ceramics(B_(4)C,SiC,TiC)as reinforcements,in improving reciprocating tribology performance and mechanical strength of A333 hybrid composites against alloy.Hollow cylindrical samples of A333/6 wt%B_(4)C/4 wt%TiC and A333/6 wt%B_(4)C/4 wt%SiC hybrid FGMMCs were developed using horizontal centrifugal casting.Metallography analysis on both composites revealed increasing ceramic gradient distribution towards outer composite wall.Particle rich zone of A333/B_(4)C/SiC hybrid FGMMC showed maximum micro-hardness(198.9 HV)and tensile strength(267.9 MPa).Elemental mapping confirmed effective distribution of ceramics and detected elemental composition of both composites.Particle rich layer of A333/B_(4)C/SiC hybrid FGMMC exhibited improved wear resistance in comparison with all three layers of A333/B_(4)C/TiC hybrid FGMMC and alloy.Third-body abrasion and tribo-chemical wear were the predominant mechanisms revealed for both composites during worn surface analysis.

Grain boundary effect on structural, optical, and electrical properties of sol-gel synthesized Fe-doped SnO_(2) nanoparticles

Tin oxide(SnO_(2)) and iron-doped tin oxide(Sn_(1-x)Fe_(x)O_(2),x=0.05 wt%,0.10 wt%) nanoparticles are synthesized by the simple sol-gel method.The structural characterization using x-ray diffraction(XRD) confirms tetragonal rutile phases of the nanoparticles.The variations in lattice parameters and relative intensity with Fe-doping concentration validate the incorporation of iron into the lattice.The compressive strain present in the lattice estimated by using peak profile analysis through using Williamson-Hall plot also exhibits the influence of grain boundary formation in the lattice.The radiative recombination and quenching observed in optical characterization by using photoluminescence spectrum(PL) and the shift in the band gap estimated from UV-visible diffused reflectance spectrum corroborate the grain boundary influence.Raman spectrum and the morphological analysis by using a field emission scanning electron microscope(FESEM) also indicate the formation of grain boundaries.The compositional analysis by using energy dispersive x-ray spectrum(EDAX) confirms Fe in the SnO_(2) lattice.The conductivity studies exhibit that the impendence increases with doping concentration increasing and the loss factor decreases at high frequencies with doping concentration increasing,which makes the Sn_(1-x)Fe_(x)O_(2) a potential candidate for device applications.

Closed Loop Control of Bi-Directional Soft Switched Quasi Z-Source DC-DC Converter

Quasi Z-source converter is a single stage soft switched power converter derived from Z-source converter topology, employing an impedance network coupling the source with the converter. The quasi Z-source source converter can buck or boost the voltage and current flow is bidirectional. The duty cycle of the switch can be adjusted to maintain constant voltage during load change. To obtain constant output voltage, proper controller design is a must. This paper presents closed loop control of quasi Z-source converter using PI controller where controller parameters are estimated using the small signal model of the entire system. The transfer function of the system with AC sweep is used to obtain appropriate proportional and integral gain constants to reduce transient dynamics and to reduce steady state error.

离心铸造梯度镁复合材料中颗粒分离的理论研究

使用理论和实验研究探究主要参数对离心铸造镁基复合材料中颗粒分布的影响。旨在描绘凝固对颗粒运动的影响,以及其他主要力量。研究结果表明,旋转速度、凝固间隔和基体与颗粒之间的密度差异会影响由离心力引起的颗粒分离区域的厚度。此外,对AZ91基体复合材料中Si C颗粒分布的理论模型和实验的比较表明,在中部区域10%(重量百分比)的分布分析是可接受的。对于每个5%、10%和15%(重量百分比)复合材料,实验和理论结果之间的差异分别为外部区域的5.83%、10.20%和4.86%,中部区域的2.64%、1.58%和2.36%。

Radiative heat transfer analysis of a concave porous fin under the local thermal non-equilibrium condition:application of the clique polynomial method and physics-informed neural networks

The heat transfer through a concave permeable fin is analyzed by the local thermal non-equilibrium(LTNE)model.The governing dimensional temperature equations for the solid and fluid phases of the porous extended surface are modeled,and then are nondimensionalized by suitable dimensionless terms.Further,the obtained nondimensional equations are solved by the clique polynomial method(CPM).The effects of several dimensionless parameters on the fin's thermal profiles are shown by graphical illustrations.Additionally,the current study implements deep neural structures to solve physics-governed coupled equations,and the best-suited hyperparameters are attained by comparison with various network combinations.The results of the CPM and physicsinformed neural network(PINN)exhibit good agreement,signifying that both methods effectively solve the thermal modeling problem.

功能梯度铜基复合材料的制备及干摩擦磨损性能（英文）

采用水平离心铸造工艺,制备功能梯度铜基复合材料,并对其非润滑滑动性能进行了研究.采用基于Taguchi的L27正交实验对石墨颗粒含量较高的空心圆柱铸件内壁厚度的磨损速率和摩擦系数进行分析.直接或间接影响磨损速率的工艺参数包括:施加的载荷(15,25和35 N)、滑动速度(1.5,2.5和3.5 m/s)和滑动距离(750,1500和2250 m).磨损速率和摩擦系数与施加的载荷和滑动距离呈比例的依赖性,而在中间滑动速度期间表现出下降.信噪比在'较小-较好'的基础上预测最小三波条件.方差分析量化参数的影响及其相互作用.采用回归分析对实验数据进行验证.在磨损表面分析过程中,通过显微镜和扫描电子显微镜发现磨损机制和机械混合层的形成.

合金成分和时效时间对Cu-Ni-Sn尖晶态合金硬度和磨损性能的影响（英文）

将含有不同成分镍和锡的铜合金在氩气气氛下进行模铸。对铸棒进行均匀化、固溶热处理后进 行不同时间时效处理。对试样进行了显微组织表征,并对试样的显微硬度和磨损率进行了测试。建立 了线性函数和径向基函数的混合模型,分析了镍、锡和时效时间对 Cu-Ni-Sn 合金显微硬度和摩擦学 行为的影响。结果表明,镍、锡成分的增加使合金基体的显微硬度增加,磨损率降低。镍和锡浓度的 增加降低了合金体系的峰值时效时间。

AN EFFICIENT 3-DIMENSIONAL DISCRETE WAVELET TRANSFORM ARCHITECTURE FOR VIDEO PROCESSING APPLICATION

This paper presents an optimized 3-D Discrete Wavelet Transform (3-DDWT) architecture. 1-DDWT employed for the design of 3-DDWT architecture uses reduced lifting scheme approach. Further the architecture is optimized by applying block enabling technique, scaling, and rounding of the filter coefficients. The proposed architecture uses biorthogonal (9/7) wavelet filter. The architecture is modeled using Verilog HDL, simulated using ModelSim, synthesized using Xilinx ISE and finally implemented on Virtex-5 FPGA. The proposed 3-DDWT architecture has slice register utilization of 5%, operating frequency of 396 MHz and a power consumption of 0.45 W.