**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**3425

# Search results for: current density

##### 3425 Effect of Current Density, Temperature and Pressure on Proton Exchange Membrane Electrolyser Stack

**Authors:**
Na Li,
Samuel Simon Araya,
Søren Knudsen Kær

**Abstract:**

This study investigates the effects of operating parameters of different current density, temperature and pressure on the performance of a proton exchange membrane (PEM) water electrolysis stack. A 7-cell PEM water electrolysis stack was assembled and tested under different operation modules. The voltage change and polarization curves under different test conditions, namely current density, temperature and pressure, were recorded. Results show that higher temperature has positive effect on overall stack performance, where temperature of 80 ℃ improved the cell performance greatly. However, the cathode pressure and current density has little effect on stack performance.

**Keywords:**
PEM electrolysis stack,
current density,
temperature,
pressure.

##### 3424 The Photon-Drag Effect in Cylindrical Quantum Wire with a Parabolic Potential

**Authors:**
Hoang Van Ngoc,
Nguyen Thu Huong,
Nguyen Quang Bau

**Abstract:**

Using the quantum kinetic equation for electrons interacting with acoustic phonon, the density of the constant current associated with the drag of charge carriers in cylindrical quantum wire by a linearly polarized electromagnetic wave, a DC electric field and a laser radiation field is calculated. The density of the constant current is studied as a function of the frequency of electromagnetic wave, as well as the frequency of laser field and the basic elements of quantum wire with a parabolic potential. The analytic expression of the constant current density is numerically evaluated and plotted for a specific quantum wires GaAs/AlGaAs to show the dependence of the constant current density on above parameters. All these results of quantum wire compared with bulk semiconductors and superlattices to show the difference.

**Keywords:**
Photon-drag effect,
constant current density,
quantum wire,
parabolic potential.

##### 3423 Heating of High-Density Hydrogen by High- Current Arc Radiation

**Authors:**
A. V. Budin,
Ph. G. Rutberg,
M. E. Pinchuk,
A. A. Bogomaz,
V. Yu. Svetova

**Abstract:**

**Keywords:**
High-density hydrogen heating by high-current
electric arc.

##### 3422 A Comparative Study on Optimized Bias Current Density Performance of Cubic ZnB-GaN with Hexagonal 4H-SiC Based Impatts

**Authors:**
Arnab Majumdar,
Srimani Sen

**Abstract:**

In this paper, a vivid simulated study has been made on 35 GHz Ka-band window frequency in order to judge and compare the DC and high frequency properties of cubic ZnB-GaN with the existing hexagonal 4H-SiC. A flat profile p^{+}pnn^{+} DDR structure of impatt is chosen and is optimized at a particular bias current density with respect to efficiency and output power taking into consideration the effect of mobile space charge also. The simulated results obtained reveals the strong potentiality of impatts based on both cubic ZnB-GaN and hexagonal 4H-SiC. The DC-to-millimeter wave conversion efficiency for cubic ZnB-GaN impatt obtained is 50% with an estimated output power of 2.83 W at an optimized bias current density of 2.5×10^{8} A/m^{2}. The conversion efficiency and estimated output power in case of hexagonal 4H-SiC impatt obtained is 22.34% and 40 W respectively at an optimum bias current density of 0.06×10^{8} A/m^{2}.

**Keywords:**
Cubic ZnB-GaN,
hexagonal 4H-SiC,
Double drift impatt diode,
millimeter wave,
optimized bias current density,
wide band gap semiconductor.

##### 3421 Current Distribution and Cathode Flooding Prediction in a PEM Fuel Cell

**Authors:**
A. Jamekhorshid,
G. Karimi,
I. Noshadi,
A. Jahangiri

**Abstract:**

**Keywords:**
Current distribution,
Flooding,
Hydrogen energysystem,
PEM fuel cell.

##### 3420 Enhancement of Pulsed Eddy Current Response Based on Power Spectral Density after Continuous Wavelet Transform Decomposition

**Authors:**
A. Benyahia,
M. Zergoug,
M. Amir,
M. Fodil

**Abstract:**

The main objective of this work is to enhance the Pulsed Eddy Current (PEC) response from the aluminum structure using signal processing. Cracks and metal loss in different structures cause changes in PEC response measurements. In this paper, time-frequency analysis is used to represent PEC response, which generates a large quantity of data and reduce the noise due to measurement. Power Spectral Density (PSD) after Wavelet Decomposition (PSD-WD) is proposed for defect detection. The experimental results demonstrate that the cracks in the surface can be extracted satisfactorily by the proposed methods. The validity of the proposed method is discussed.

**Keywords:**
NDT,
pulsed eddy current,
continuous wavelet transform,
Mexican hat wavelet mother,
defect detection,
power spectral density.

##### 3419 Characterization of Pure Nickel Coatings Fabricated under Pulse Current Conditions

**Authors:**
M. Sajjadnejad,
H. Omidvar,
M. Javanbakht,
A. Mozafari

**Abstract:**

**Keywords:**
Current density,
Duty cycle,
Microstructure,
Nickel,
Pulse frequency.

##### 3418 The Mechanical and Electrochemical Properties of DC-Electrodeposited Ni-Mn Alloy Coating with Low Internal Stress

**Authors:**
Chun-Ying Lee,
Kuan-Hui Cheng,
Mei-Wen Wu

**Abstract:**

**Keywords:**
DC plating,
internal stress,
leveling power,
Ni-Mn
coating.

##### 3417 Improved Small-Signal Characteristics of Infrared 850 nm Top-Emitting Vertical-Cavity Lasers

**Authors:**
Ahmad Al-Omari,
Osama Khreis,
Ahmad M. K. Dagamseh,
Abdullah Ababneh,
Kevin Lear

**Abstract:**

*f*

_{-3dB}) of 14 GHz and a resonance frequency (

*f*

_{R}) of 9.5 GHz at a bias current density (

*J*) of only 4.3 kA/cm

_{bias}^{2}, which corresponds to an improved

*f*

_{-3dB}

^{2}/

*J*ratio of 44 GHz

_{bias}^{2}/kA/cm

^{2}. At higher and lower bias current densities, the

*f*

_{-3dB}

^{2}/

*J*ratio decreased to about 30 GHz

_{bias}^{2}/kA/cm

^{2}and 18 GHz

^{2}/kA/cm

^{2}, respectively. Examination of the analogue modulation response demonstrated that the presented VCSELs displayed a steady

*f*

_{-3dB}/

*f*

_{R}ratio of 1.41±10% over the whole range of the bias current (1.3

*I*

_{th}to 6.2

*I*

_{th}). The devices also demonstrated a maximum modulation bandwidth (

*f*

_{-3dB max}) of more than 16 GHz at a bias current less than the industrial bias current standard for reliability by 25%.

**Keywords:**
Current density,
High-speed VCSELs,
Modulation bandwidth,
Small-Signal Characteristics,
Thermal impedance,
Vertical-cavity surface-emitting lasers.

##### 3416 The Light-Effect in Cylindrical Quantum Wire with an Infinite Potential for the Case of Electrons: Optical Phonon Scattering

**Authors:**
Hoang Van Ngoc,
Nguyen Vu Nhan,
Nguyen Quang Bau

**Abstract:**

The light-effect in cylindrical quantum wire with an infinite potential for the case of electrons, optical phonon scattering, is studied based on the quantum kinetic equation. The density of the direct current in a cylindrical quantum wire by a linearly polarized electromagnetic wave, a DC electric field, and an intense laser field is calculated. Analytic expressions for the density of the direct current are studied as a function of the frequency of the laser radiation field, the frequency of the linearly polarized electromagnetic wave, the temperature of system, and the size of quantum wire. The density of the direct current in cylindrical quantum wire with an infinite potential for the case of electrons – optical phonon scattering is nonlinearly dependent on the frequency of the linearly polarized electromagnetic wave. The analytic expressions are numerically evaluated and plotted for a specific quantum wire, GaAs/GaAsAl.

**Keywords:**
The light-effect,
cylindrical quantum wire with an infinite potential,
the density of the direct current,
electrons - optical phonon scattering.

##### 3415 Controlling Water Temperature during the Electrocoagulation Process Using an Innovative Flow Column-Electrocoagulation Reactor

**Authors:**
Khalid S. Hashim,
Andy Shaw,
Rafid Alkhaddar,
Montserrat Ortoneda Pedrola

**Abstract:**

**Keywords:**
Water temperature,
flow column,
electrocoagulation.

##### 3414 The Analysis of Photoconductive Semiconductor Switch Operation in the Frequency of 10 GHz

**Authors:**
Morteza Fathipour,
Seyed Nasrolah Anousheh,
Kaveh Ghiafeh Davoudi,
Vala Fathipour

**Abstract:**

**Keywords:**
Band X,
Gallium-Arsenide,
Mixed mode,
PCSS,
Photoconductivity.

##### 3413 Study of the Transport of Multivalent Metal Cations through Cation-Exchange Membranes by Electrochemical Impedance Spectroscopy

**Authors:**
V. Pérez-Herranz,
M. Pinel,
E. M. Ortega,
M. García-Gabaldón

**Abstract:**

In the present work, Electrochemical Impedance Spectrocopy (EIS) is applied to study the transport of different metal cations through a cation-exchange membrane. This technique enables the identification of the ionic-transport characteristics and to distinguish between different transport mechanisms occurring at different current density ranges. The impedance spectra are dependent on the applied dc current density, on the type of cation and on the concentration. When the applied dc current density increases, the diameter of the impedance spectra loops increases because all the components of membrane system resistance increase. The diameter of the impedance plots decreases in the order of Na(I), Ni(II) and Cr(III) due to the increased interactions between the negatively charged sulfonic groups of the membrane and the cations with greater charge. Nyquist plots are shifted towards lower values of the real impedance, and its diameter decreases with the increase of concentration due to the decrease of the solution resistance.

**Keywords:**
Ion-exchange Membranes,
Electrochemical
Impedance Espectroscopy,
Multivalent Metal Cations.

##### 3412 Orthogonal Polynomial Density Estimates: Alternative Representation and Degree Selection

**Authors:**
Serge B. Provost,
Min Jiang

**Abstract:**

**Keywords:**
kernel density estimation,
orthogonal polynomials,
moment-based methodologies,
density approximation.

##### 3411 Behavior of Current in a Semiconductor Nanostructure under Influence of Embedded Quantum Dots

**Authors:**
H. Paredes Gutiérrez,
S. T. Pérez-Merchancano

**Abstract:**

Motivated by recent experimental and theoretical developments, we investigate the influence of embedded quantum dot (EQD) of different geometries (lens, ring and pyramidal) in a double barrier heterostructure (DBH). We work with a general theory of quantum transport that accounts the tight-binding model for the spin dependent resonant tunneling in a semiconductor nanostructure, and Rashba spin orbital to study the spin orbit coupling. In this context, we use the second quantization theory for Rashba effect and the standard Green functions method. We calculate the current density as a function of the voltage without and in the presence of quantum dots. In the second case, we considered the size and shape of the quantum dot, and in the two cases, we worked considering the spin polarization affected by external electric fields. We found that the EQD generates significant changes in current when we consider different morphologies of EQD, as those described above. The first thing shown is that the current decreases significantly, such as the geometry of EQD is changed, prevailing the geometrical confinement. Likewise, we see that the current density decreases when the voltage is increased, showing that the quantum system studied here is more efficient when the morphology of the quantum dot changes.

**Keywords:**
Quantum semiconductors,
nanostructures,
quantum dots,
spin polarization.

##### 3410 A New Knapsack Public-Key Cryptosystem Based on Permutation Combination Algorithm

**Authors:**
Min-Shiang Hwang,
Cheng-Chi Lee,
Shiang-Feng Tzeng

**Abstract:**

**Keywords:**
Public key,
Knapsack problem,
Knapsack cryptosystem,
low-density attack.

##### 3409 Iron Recovery from Red Mud as Zero-Valent Iron Metal Powder Using Direct Electrochemical Reduction Method

**Authors:**
Franky Michael Hamonangan Siagian,
Affan Maulana,
Himawan Tri Bayu Murti Petrus,
Panut Mulyono,
Widi Astuti

**Abstract:**

In this study, the feasibility of the direct electrowinning method was used to produce zero-valent iron from red mud. The red mud sample came from the Tayan mine, Indonesia, which contains high hematite (Fe2O3). Before electrolysis, the samples were characterized by various analytical techniques (ICP-AES, SEM, XRD) to determine their chemical composition and mineralogy. The direct electrowinning method of red mud suspended in NaOH was introduced at low temperatures ranging from 30-110 °C. Current density and temperature variations were carried out to determine the optimum operation of the direct electrowinning process. Cathode deposits and residues in electrochemical cells were analyzed using XRD, XRF, and SEM to determine the chemical composition and current recovery. The low-temperature electrolysis current efficiency on Redmud can reach 11.8% recovery at a current density of 796 A/m². The moderate performance of the process was investigated with red mud, which was attributed to the troublesome adsorption of red mud particles on the cathode, making the reduction far less efficient than that with hematite.

**Keywords:**
Alumina,
electrochemical reduction,
iron production,
red mud.

##### 3408 Patterned Growth of ZnO Nanowire Arrays on Zinc Foil by Thermal Oxidation

**Authors:**
Farid Jamali Sheini,
Dilip S. Joag,
Mahendra A. More

**Abstract:**

**Keywords:**
ZnO,
Nanowires,
Thermal oxidation,
FieldEmission.

##### 3407 Energy Density Increasing in the Channel of Super-High Pressure Megaampere Discharge due to Resonance of Different Type Oscillations of the Channel

**Authors:**
Ph. G. Rutberg,
A. V. Budin,
M. E. Pinchuk,
A. A. Bogomaz,
A. G. Leks,
S. Yu. Losev,
andA. A. Pozubenkov

**Abstract:**

Discharges in hydrogen, ignited by wire explosion, with current amplitude up to 1.5 MA were investigated. Channel diameter oscillations were observed on the photostreaks. Voltage and current curves correlated with the photostreaks. At initial gas pressure of 5-35 MPa the oscillation period was proportional to square root of atomic number of the initiating wire material. These oscillations were associated with aligned magnetic and gas-kinetic pressures. At initial pressure of 80-160 MPa acoustic pressure fluctuations on the discharge chamber wall were increased up to 150 MPa and there were the growth of voltage fluctuations on the discharge gap up to 3 kV simultaneously with it. In some experiments it was observed abrupt increase in the oscillation amplitude, which can be caused by the resonance of the acoustic oscillations in discharge chamber volume and the oscillations connected with alignment of the gaskinetic pressure and the magnetic pressure, as far as frequencies of these oscillations are close to each other in accordance with the estimates and the experimental data. Resonance of different type oscillations can produce energy density increasing in the discharge channel. Thus, the appropriate initial conditions in the experiment allow to increase the energy density in the discharge channel

**Keywords:**
High-current gas discharges,
high pressure
hydrogen,
discharge channel oscillations.

##### 3406 Performance of an Electrocoagulation Process in Treating Direct Dye: Batch and Continuous Upflow Processes

**Authors:**
C. Phalakornkule,
S. Polgumhang,
W. Tongdaung

**Abstract:**

**Keywords:**
Decolorization,
Direct Dye,
Electrocoagulation,
Textile Wastewater,
Upflow Reactor.

##### 3405 Bio-Heat Transfer in Various Transcutaneous Stimulation Models

**Authors:**
Trevor E. Davis,
Isaac Cassar,
Yi-Kai Lo,
Wentai Liu

**Abstract:**

This study models the use of transcutaneous electrical nerve stimulation on skin with a disk electrode in order to simulate tissue damage. The current density distribution above a disk electrode is known to be a dynamic and non-uniform quantity that is intensified at the edges of the disk. The non-uniformity is subject to change through using various electrode geometries or stimulation methods. One of these methods known as edge-retarded stimulation has shown to reduce this edge enhancement. Though progress has been made in modeling the behavior of a disk electrode, little has been done to test the validity of these models in simulating the actual heat transfer from the electrode. This simulation uses finite element software to couple the injection of current from a disk electrode to heat transfer described by the Pennesbioheat transfer equation. An example application of this model is studying an experimental form of stimulation, known as edge-retarded stimulation. The edge-retarded stimulation method will reduce the current density at the edges of the electrode. It is hypothesized that reducing the current density edge enhancement effect will, in turn, reduce temperature change and tissue damage at the edges of these electrodes. This study tests this hypothesis as a demonstration of the capabilities of this model. The edge-retarded stimulation proved to be safer after this simulation. It is shown that temperature change and the fraction of tissue necrosis is much greater in the square wave stimulation. These results bring implications for changes of procedures in transcutaneous electrical nerve stimulation and transcutaneous spinal cord stimulation as well.

**Keywords:**
Bioheat transfer,
Electrode,
Neuroprosthetics,
TENS,
Transcutaneous stimulation.

##### 3404 Research on the Correlation of the Fluctuating Density Gradient of the Compressible Flows

**Authors:**
Yasuo Obikane

**Abstract:**

**Keywords:**
Turbulence Modeling ,
Density Gradient Correlation,
Compressible

##### 3403 Breakdown of LDPE Film under Heavy Water Absorption

**Authors:**
Eka PW,
T. Okazaki,
Y. Murakami,
N.,
Hozumi,
M. Nagao

**Abstract:**

**Keywords:**
Low density polyethylene,
heavy water absorption,
conduction current,
temperature rise.

##### 3402 Traffic Density Estimation for Multiple Segment Freeways

**Authors:**
Karandeep Singh,
Baibing Li

**Abstract:**

**Keywords:**
Density estimation,
Kalman filter,
speed-densityrelationship,
Traffic surveillance.

##### 3401 The Statistical Properties of Filtered Signals

**Authors:**
Ephraim Gower,
Thato Tsalaile,
Monageng Kgwadi,
Malcolm Hawksford.

**Abstract:**

In this paper, the statistical properties of filtered or convolved signals are considered by deriving the resulting density functions as well as the exact mean and variance expressions given a prior knowledge about the statistics of the individual signals in the filtering or convolution process. It is shown that the density function after linear convolution is a mixture density, where the number of density components is equal to the number of observations of the shortest signal. For circular convolution, the observed samples are characterized by a single density function, which is a sum of products.

**Keywords:**
Circular Convolution,
linear Convolution,
mixture density
function.

##### 3400 Corrosion Evaluation of Zinc Coating Prepared by Two Types of Electric Currents

**Authors:**
M. Sajjadnejad,
H. Karimi Abadeh

**Abstract:**

In this research, zinc coatings were fabricated by electroplating process in a sulfate solution under direct and pulse current conditions. In direct and pulse current conditions, effect of maximum current was investigated on the coating properties. Also a comparison was made between the obtained coatings under direct and pulse current. Morphology of the coatings was investigated by scanning electron microscopy (SEM). Corrosion behavior of the coatings was investigated by potentiodynamic polarization test. In pulse current conditions, the effect of pulse frequency and duty cycle was also studied. The effect of these conditions and parameters were also investigated on morphology and corrosion behavior. All of DC plated coatings are showing a distinct passivation area in -1 to -0.4 V range. Pulsed current coatings possessed a higher corrosion resistance. The results showed that current density is the most important factor regarding the fabrication process. Furthermore, a rise in duty cycle deteriorated corrosion resistance of coatings. Pulsed plated coatings performed almost 10 times better than DC plated coatings.

**Keywords:**
Corrosion,
duty cycle,
pulsed current,
zinc.

##### 3399 Creep Transition in a Thin Rotating Disc Having Variable Density with Inclusion

**Authors:**
Pankaj,
Sonia R. Bansal

**Abstract:**

**Keywords:**
Elastic-Plastic,
Inclusion,
Rotating disc,
Stress,
Strain rates,
Transition,
variable density.

##### 3398 Density Estimation using Generalized Linear Model and a Linear Combination of Gaussians

**Authors:**
Aly Farag,
Ayman El-Baz,
Refaat Mohamed

**Abstract:**

In this paper we present a novel approach for density estimation. The proposed approach is based on using the logistic regression model to get initial density estimation for the given empirical density. The empirical data does not exactly follow the logistic regression model, so, there will be a deviation between the empirical density and the density estimated using logistic regression model. This deviation may be positive and/or negative. In this paper we use a linear combination of Gaussian (LCG) with positive and negative components as a model for this deviation. Also, we will use the expectation maximization (EM) algorithm to estimate the parameters of LCG. Experiments on real images demonstrate the accuracy of our approach.

**Keywords:**
Logistic regression model,
Expectationmaximization,
Segmentation.

##### 3397 Parametric Analysis of Solid Oxide Fuel Cell Using Lattice Boltzmann Method

**Authors:**
Abir Yahya,
Hacen Dhahri,
Khalifa Slimi

**Abstract:**

The present paper deals with a numerical simulation of temperature field inside a solid oxide fuel cell (SOFC) components. The temperature distribution is investigated using a co-flow planar SOFC comprising the air and fuel channel and two-ceramic electrodes, anode and cathode, separated by a dense ceramic electrolyte. The Lattice Boltzmann method (LBM) is used for the numerical simulation of the physical problem. The effects of inlet temperature, anode thermal conductivity and current density on temperature distribution are discussed. It was found that temperature distribution is very sensitive to the inlet temperature and the current density.

**Keywords:**
Solid oxide fuel cell,
Heat sources,
temperature,
Lattice Boltzmann method.

##### 3396 Measuring Heterogeneous Traffic Density

**Authors:**
V. Thamizh Arasan,
G. Dhivya

**Abstract:**

**Keywords:**
Density Measurement,
Heterogeneity,
Occupancy,
Traffic Flow.