Improved formic acid oxidation using electrodeposited Pd–Cd electrocatalysts in sulfuric acid solution

In the present research, nanostructured Pd–Cd alloy electrocatalysts with different compositions were produced using the electrodeposition process. The morphology of the samples was studied by scanning electron microscopy analysis. Also, the elemental composition of the samples was determined by energy-dispersive X-ray spectroscopy and elemental mapping tests. Tafel polarization and electrochemical impedance spectroscopy methods were employed to determine the electrochemical corrosion properties of the synthesized samples in a solution containing 0.5 M sulfuric acid and 0.1 M formic acid. The linear sweep voltammetry, cyclic voltammetry, and chronoamperometry techniques were also employed to evaluate the electrocatalytic activity of prepared samples toward the oxidation of formic acid. In this respect, the influence of some factors such as formic acid and sulfuric acid concentrations and also potential scan rate was investigated. Compared to the pure Pd sample, the Pd–Cd samples were more reactive for the oxidation of formic acid. Besides, the sample with a lower amount of Pd (Pd_1·3Cd) demonstrated much higher electrocatalytic activity than the Pd_7·1Cd and Pd_2·1Cd samples. The observed high mass activity of 15.06 A mg^?1_Pd for the Pd_1·3Cd sample which is 21.1 times higher than Pd/C is an interesting result of this study.     

Learning nonlinear dynamics with behavior ordinary/partial/system of the differential equations: looking through the lens of orthogonal neural networks

In this paper, size-dependent dynamic stability of axially loaded functionally graded (FG) composite truncated conical microshells with magnetostrictive facesheets surrounded by nonlinear viscoelastic foundations including a two-parameter Winkler–Pasternak medium augmented via a Kelvin–Voigt viscoelastic approach is analyzed considering nonlinear cubic stiffness. To this purpose, von Karman-type kinematic nonlinearity along with modified couple stress theory of elasticity was applied to third-order shear deformation conical shell theory in the presence of magnetic permeability tensor and magnetic fluxes. The numerical technique of generalized differential quadrature (GDQ) was used for the solution of microstructural-dependent dynamic stability responses of FG composite truncated conical microshells. It was seen that moving from prebuckling to postbuckling domain somehow increased the significance of couple stress type of size dependency on frequency. In addition, within both prebuckling and postbuckling regimes, an increase of material gradient index decreased the importance of couple stress type of size dependency on the frequency of an axially loaded FG composite truncated conical microshell. Furthermore, it was revealed that by applying a positive magnetic field to an axially loaded truncated conical microshell with magnetostrictive facesheets, its frequency at a specific axial load value was increased in prebuckling domain and decreased in postbuckling domain. However, this pattern was reversed by applying a negative magnetic field.

     

A C5 parallel robot identification and control

The paper proposes a controller scheme based on a priori identification for a C5 parallel robot. First we realize the identification of dynamic parameters of the robot using the Least Squares technique. Different data are used for this step of identification. The cross validation permitted to select and confirm the identified parameters. After, a control scheme (computed torque) is applied to control the C5 parallel robot. The functions of this control scheme are based on precedent identified parameters. In order to reduce the effect of the identification error, we have added a robustness term based on sliding mode technique. The stability of the system in closed loop is presented using the Lyapunov principle. Experimental results of identification and control are presented and show the effectiveness of our methodology.     

DISTRIBUTION AND HABITAT USE OF THE MISSOURI RIVER AND LOWER YELLOWSTONE RIVER BENTHIC FISHES FROM 1996 TO 1998: A BASELINE FOR FISH COMMUNITY RECOVERY

Past and present Missouri River management practices have resulted in native fishes being identified as in jeopardy. In 1995, the Missouri River Benthic Fishes Study was initiated to provide improved information on Missouri River fish populations and how alterations might affect them. The study produced a baseline against which to evaluate future changes in Missouri River operating criteria. The objective was to evaluate population structure and habitat use of benthic fishes along the entire mainstem Missouri River, exclusive of reservoirs. Here we use the data from this study to provide a recent‐past baseline for on‐going Missouri River fish population monitoring programmes along with a more powerful method for analysing data containing large percentages of zero values. This is carried out by describing the distribution and habitat use of 21 species of Missouri River benthic fishes based on catch‐per‐unit area data from multiple gears. We employ a Bayesian zero‐inflated Poisson model expanded to include continuous measures of habitat quality (i.e. substrate composition, depth, velocity, temperature, turbidity and conductivity). Along with presenting the method, we provide a relatively complete picture of the Missouri River benthic fish community and the relationship between their relative population numbers and habitat conditions. We demonstrate that our single model provides all the information that is often obtained by a myriad of analytical techniques. An important advantage of the present approach is reliable inference for patterns of relative abundance using multiple gears without using gear efficiencies. Copyright © 2011 John Wiley & Sons, Ltd.     

Improvement of Grain Size and Dome Height of Microalloyed Steels Using Taguchi Method Based on Grey Relational Grade in Controlled Rolling

An efficient approach was introduced for improving the condition of major controlled rolling process parameters of roughing, finishing and coiling temperatures and optimizing these parameters to obtain minimum grain size and maximum dome height simultaneously. Taguchi method combined with grey relational analysis was applied to achieve optimum grain size and dome height during controlled rolling process. For this purpose, four levels for the above temperatures were chosen and sixteen experiments were conducted based on orthogonal array of Taguchi method. Based on Taguchi approach, signal-to-noise (S/N) ratios were calculated and used in order to obtain the optimum levels for every input parameter. Analysis of variance revealed that finishing and coiling temperatures have the maximum effect on the grain size and dome height of microalloyed steels. The confirmation tests with the optimal levels of parameters indicated that the grain size and dome height of controlled rolled microalloyed steels can be improved effectively through this approach.     

Complete convergence of stochastic approximation algorithm in ℝd under random noises

In this article, we study a stochastic approximation algorithm that approximates the exact root θ of a function M defined in ?^d into ?^d. The function M cannot be known exactly, but only noisy measurements are available at each point x_n with the error ξ_n. The sequence of noise (_ξn)n is random; we treat both cases where it is independent and dependent and we establish the complete convergence of the approximated sequence of θ.     

A new arrangement of Z‐source AC–AC converter and its closed‐loop control system

In this study, a Z‐source alternating current‐to‐alternating current (AC–AC) converter with a specific topology, which can provide both buck and boost modes, is investigated. This converter, which can be implemented easily, utilizes only two switches with complemented commands. A comparison between the Z‐source AC–AC converter and a conventional thyristor voltage controlled one is presented here, and it shows that in the most areas, the Z‐source converter provides a faster response and lower total harmonic distortion of the output currents than the conventional one. Moreover, the Z‐source converter is also extended to the multiphase systems. In addition, a new arrangement of this converter is proposed here to remove the isolated single‐phase sources. Furthermore, an open‐loop method is proposed for soft‐starting applications. Finally, a closed‐loop control system is also suggested for a three‐phase Z‐source converter to soft start and control the speed of an induction motor. Computer simulations show the validity and effectiveness of the proposed schemes. Copyright © 2014 John Wiley & Sons, Ltd.     

Graphene Nanoplatelet (GNP)-Incorporated AZ31 Magnesium Nanocomposite: Microstructural,Mechanical and Tribological Properties

Graphene nanoplatelets (GNPs), despite their unique properties, were not widely investigated as reinforcement in metal matrix nanocomposites. The nanocomposite was fabricated by adding 15-nm-thick GNPs to AZ31 magnesium alloy via friction stir processing (FSP). Mechanical, frictional and wear properties were investigated. It was observed that refined microstructure with a range of 3–9 µm grain size and the presence of GNPs, i.e., reinforcing particles, improved the tensile properties and increased the ultimate tensile strength to 278 MPa. FSP increased the strain-to-fail by 133% compared to that of base metal, while it was decreased by adding GNPs. Moreover, the presence of GNPs decreased the adhesive wear mechanism by squeezing out, smudging on the surface and, finally, forming a protective layer between the sliding surfaces. Hence, the coefficient of friction was decreased to 60% and the range of fluctuations in friction plot was confined by adding GNPs. They were further decreased by increasing the normal load and sliding velocity due to easier debonding of the GNPs and the surrounding AZ31 Mg matrix resulting in forming a lubricating layer between sliding surfaces.