Green facile thermal decomposition synthesis,characterization and electrochemical hydrogen storage characteristics of ZnAl2O4 nanostructure

The ZnAl₂O₄ spinel was synthesized by a facile thermal decomposition method using green chemistry. For the first time, the electrochemical hydrogen storage performances and mechanisms of the ZnAl₂O₄ was studied by the galvanostatic charge-discharge method in 6 M KOH aqueous medium under 1 mA current. Anionic, cationic and polymeric surfactants were used to increase of hydrogen storage and specific area of ZnAl₂O₄ spinel. The composition, structure, morphology and specific surface area of the samples were characterized. The maximum measured discharge capacities of ZnAl₂O₄, ZnAl₂O₄/CTAB, ZnAl₂O₄/PVP and ZnAl₂O₄/SDS were 1250, 3000, 3250 and 4000 mAh/g, respectively. These samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDS), N₂ adsorption (BET) and transmission electron microscope (TEM).     

Hydrogen evolution assisted electrodeposition of bimetallic 3D nano/micro-porous PtPd films and their electrocatalytic performance

Self-supporting PtPd bimetallic catalysts with three-dimensional (3D) porous structures and a greatly enhanced surface area are firstly fabricated at a glassy carbon electrode (GCE) by a one-step strategy of potentiostatic co-electrodeposition utilizing hydrogen bubble dynamic templates. The atomic ratio of Pt/Pd in the bimetallic catalysts is varied by changing the composition of the electrodeposition solution. The 3D porous PtPd films are characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and examined as electrocatalysts for the electro-oxidation of methanol using cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS). Experimental results demonstrate that a small amount of Pd plays the predominant role in the formation of 3D porous structure for PtPd bimetallic catalysts and is an excellent catalytically enhancing agent for the Pt catalyst towards methanol electro-oxidation. The study on electrocatalytic performance of mono and bimetallic catalysts towards formic acid electro-oxidation also reveals the better activity of 3D porous Pd film for this reaction.     

Rapid prediction of hydrate condition for promoting CO2 recovery in the oil and gas industry

Gas hydrates may form in the petroleum and gas industry and can lead to significant problems such as plugging the pipelines and increasing velocity movement of the hydrate plugs in the pipelines. In this contribution, a simple strategy based on principal component analysis and partial least square methods has been utilized in order to estimate hydrate formation condition of carbon dioxide and tetra butyl ammonium chloride. In this regard, the developed tool has been evaluated by some reported data points in order to obtain its accuracy. This tool was simple to apply and can be of great help for gas transmission engineers to have an accurate estimation of hydrate conditions.     

Minimization of Wireless Sensor Network Energy Consumption Through Optimal Modulation Scheme and Channel Coding Strategy

Wireless sensor networks (WSNs) are composed of sensor nodes generally powered by batteries, for which recharging or replacement is difficult. Since battery technology has not progressed as rapidly as semiconductor technology, energy efficiency has become increasingly important in WSN. On the other hand, data exchanged between nodes are vulnerable to corruption by errors induced by random noise, signal fading and other factors. Therefore, improving link reliability and reducing energy consumption are prime concerns in the design of wireless sensor networks. In this context, performing optimal modulation schemes with suitable channel coding process is a crucial task at the physical layer of this class of networks. This paper investigates the best modulation strategy to minimize the total energy consumption required to send a given number of bits. Energy consumption with both uncoded and coded modulation techniques including M-ary QAM (MQAM), M-ary PSK (MPSK), M-ary FSK (MFSK) and MSK is analytically analyzed and simulated over transmission time, modulation rate and transmission distance. A comparative analysis in terms of energy consumption and probability of Bit Error Rate (BER) referring to MSK modulation with proper Error Control Codes (ECC) approach is presented in this paper. We show that the gain achieved with coded MSK scheme is very promising for obtaining optimal energy network consumption.     

Extracting a general iterative method from an Adomian decomposition method and comparing it to the variational iteration method

In this work, a new form of Adomian decomposition method (ADM) is presented; by this form a general iterative method can be achieved in which there is no need of calculating Adomian polynomials. Also, this general iterative method is compared with the Adomian decomposition method and variational iteration method (VIM) and its advantages are expressed.     

Configuration selection for reconfigurable control of piecewise affine systems

In this paper, the problem of configuration selection, i.e. sensor/actuator placement for piecewise affine (PWA) systems subject to both sensor and actuator faults is considered. A method is proposed that provides a tool for the design phase to decide about the optimal placement of sensor/actuators where the reconfigurability of the system subject to sensor and actuator faults is also taken into account. Using a lattice of possible configurations (sensor/actuator placements), the reconfigurability of the system subject to faults for each configuration is evaluated and based on that one can draw conclusions about the reconfigurability of the system and the optimal configuration in the architecture design phase. A reconfigurable control must ensure stability of the reconfigured system and, if possible, a graceful degradation in the performance. Therefore, in the proposed reconfigurability analysis, we consider both stabilisability and performance of the system. The efficiency of the proposed method is demonstrated in several numerical examples.     

Capacitive behavior of nanostructured MnO2 prepared by sonochemistry method

Nanostructured manganese dioxide has been successfully prepared by a sonochemical method from an aqueous solution of potassium bromate and manganese sulfate. Changing the proportions of reagents leads either to γ- or layered structures of MnO₂. The capacitive characteristics of the samples were systematically investigated in aqueous electrolytes through means of cyclic voltammetry and chronopotentiometry methods. The electrochemical properties of MnO₂ were strongly affected by the pH of electrolyte employed and this material exhibited ideally capacitive behavior in 0.5 M aqueous Na₂SO₄ solution. A maximum specific capacitance of 344 F g⁻¹ was obtained for the layered structure determined via cyclic voltammetry at a scan rate of 5 mV s⁻¹ in 0.5 M aqueous Na₂SO₄ solution at pH 3.3. Excellent electrochemical reversibility of the materials was also demonstrated.Layered structure MnO₂ showed higher energy density at high power density than the γ-structure material.Impedance spectroscopy studies revealed that charge transfer resistance of the γ-structure oxide has higher value than that of the layered structure.     

High speed residue number system comparison for the moduli set {2^n-1, 2^n, 2^n＋}

The Residue Number System （RNS） exploits advantages of fast computing, parallelism and fault tolerant because of its carry-free property in operations. This essential property gives RNS this ability to eliminate the problem of carry propagations in calculations and provides high-speed computing consequently. In RNS some operations like addition and multiplication can be done in parallel, faster and with less complexity than conventional numeric systems so it is used in many applications like Digital Signal Processing （DSP）, Cryptography and Image Processing. Normally these applications require comparison in their operations. Comparison is a fundamental operation in numeric systems. On the other hand, the noticed property makes comparison difficult and complex in RNS. The pervious methods or algorithms for RNS comparison used redundant moduli set, ROM look-up tables or implemented complete RNS to binary（R/B） convert. We propose a new RNS comparison technique, which performs RNS comparison without using a redundant module and complete converting from RNS to binary system. Our technique implements RNS comparison much faster applying a few more hardware than previous techniques.     

Analysis of a joint entry- and distance-based cordon pricing scheme: a dynamic modeling approach

Railway Engineering Science - Transportation demand management (TDM) covers strategies for reducing traffic congestion within the affected urban areas. Congestion pricing includes a branch of TDM...     

The Passive Film Characteristics of Cold Deformed Pure Copper

In the present study, the effect of cold deformation on the electrochemical and passive behaviors of pure copper in 0.01 M NaOH solution was investigated. The dislocation density in cold deformation was calculated using a recently developed JAVA-based software, materials analysis using diffraction, based on Rietveld’s whole x-ray pattern fitting methodology. At the thickness reduction of 70%, the microhardness measured as 125.30 HV, which is 1.56 times than that in the annealed pure copper (80.25 HV). Potentiodynamic polarization plots and electrochemical impedance spectroscopy measurements showed that increasing the cold deformation offers better conditions for forming the passive films. In the Mott-Schottky analysis, no evidence for n-type behavior was obtained which indicates that the oxygen vacancies and the copper interstitials did not have any significant population density in the passive films. Also, this analysis revealed that with increasing cold deformation, the acceptor density of the passive films decreased.