bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and experimental investigation of cavity-backed arbitrary slot antennas
Authors: Moheb H. , Shaker J. , Shafai L.
Published: December 2010

The equivalence principle and the generalized network formulation are used to model the tangential electric field on arbitrary apertures, backed by a rectangular wave guide or cavity, in terms of equivalent magnetic currents. The coupling is through the aperture whose characteristics are expressed by the aperture admittance matrices of the cavity and half-space regions. The aperture coupling is then expressed as the sum of the two independent aperture admittances, with source terms related to the incident field. The result is an integral equation for the unknown aperture current. This integral equation is then reduced to a matrix equation using the method of moments. The formulation is then used to, investigate the electrical characteristics, i.e., aperture field distribution, aperture admittance, and radiation patterns of low-gain antennas such as H, cross, end-loaded, and centre-loaded slots backed by a cavity. Experimental results are also provided to verify the numerical results.
Analyses of the 5d2–5d7p transitions in the Ta IV and W V spectra
Authors: Churilov S. S. , Kildiyarova R. R. , Joshi Y. N.
Published: December 2010

The spectra of tantalum and tungsten were photographed on a 3 m normal incidence spectrograph using a sliding spark and a triggered spark light source. The 5d2–5d7p transitions in the Ta IV and W V were investigated. All 12 levels of the 5d7p configuration in both Ta IV and W V have been established. The 5d7p and 5d5f configuration interaction has helped us to identify three of the four missing levels of the 5d5f configuration in Ta IV and one missing level in W V Sixty-six lines in Ta IV and 45 lines in W V have been additionally classified. Parametric calculations interpret the observed spectra satisfactorily. Ionization potentials of Ta IV and WV have been estimated to be Ta V2D3/2 = 294 700 ± 1500 cm−1 (36.53 ± 0.18 eV) and W VI 2D3/2 = 421 300 ± 800 cm−1 (52.22 ± 0.10 eV), respectively.
Multi-interaction of multi-nucleon transfer reactions in the whole-angle region
Authors: Farra A. A.
Published: December 2010

Heavy-ion transfer reactions are studied using the exact finite-range DWBA (distorted wave Born approximation) calculations. To investigate the differential cross sections in the whole-angle region the reaction mechanism is considered as a coherent sum of direct and exchange processes. Both the double-folding microscopic nucleon–nucleon interaction and phenomenological Woods–Saxon form are used for the real and imaginary distorting potentials in the initial and final channels, respectively. The present calculations are in good agreement with the experimental data in the whole angular range. The inclusion of the exchange process improves the cross section's magnitude explicitly and leads to a better description of the backward oscillations. The values of the extracted normalization coefficients obtained are reasonable.
Quantizing orthodox gravity
Authors: Shiekh A. Y.
Published: December 2010

A tentative approach is made to quantizing gravity with a modified renormalization scheme, and is illustrated for the example of a massive scalar field with gravity.
Note on gauging cosmological density perturbations
Authors: Couch W. E. , Torrence R. J.
Published: December 2010

It is shown that a convenient identification gauge-invariant formalism for the study of cosmological perturbations has additional potential gauge freedom, which has not always been correctly identified, in solutions of the field equations.
Electronic transition moments for the Herzberg I bands of O2
Authors: England J. P. , Lewis B. R. , Gibson S. T.
Published: December 2010

Recently published extensive high-resolution measurements of absolute integrated photoabsorption cross sections for rotational lines of the (ν′ = 4–11, ν″ = 0) bands of the O2 Herzberg I system have been fitted using general rotational line-strength formulae for [Formula: see text] transitions. Good fits were obtained using only three independent electronic transition-moment parameters that accounted for transition strength borrowed from electric-dipole-allowed transitions through spin-orbit and orbit-rotation interactions involving both upper and lower states of the transition. Absolute values of transition-moment parameters have been obtained, corresponding to R-centroids from 1.29 to 1.32 Å (1 Å = 10−10 m). Band oscillator strengths derived from the calculated integrated line strengths are in good agreement with most experimental measurements. Principal electronic matrix elements have been estimated by assuming that strength is borrowed from only two electric-dipole-allowed transitions.
L X-ray fluorescence cross sections in the atomic region 59 ≤ Z ≤ 82 excited by 16.58 keV photons
Authors: Rao D. V. , Cesareo R. , Gigante G. E.
Published: December 2010

LL, Lα, Lβ, and Lγ X-ray fluorescence cross sections for Pr, Sm, Gd, Dy, Ho, Er, Yb, Pt Au, and Pb were measured at the excitation energy 16.58 keV. An X-ray tube and a secondary excitor system was used instead of radioisotopes for the measurements. Experimental cross sections are compared with the theoretical estimates based on relativistic Dirac–Hartree–Slater theory. Average L-shell fluorescence yields [Formula: see text] are deduced using the present experimental cross sections and the theoretical subshell photoionization cross sections. The derived average fluorescence yields are fitted by least squares to polynomials in Z of the form ΣnanZn and compared with theoretical and earlier fitted values. Good agreement is observed ' between the experimental results and the theoretical estimates based on relativistic Dirac–Hartree–Slater theory.
Double L-shell ionization Kα satellites in electron-excited X-ray emission spectrum of metallic cobalt
Authors: Soni S. N.
Published: December 2010

The Kα5−8 satellite spectrum of metallic cobalt, excited by a 25 keV electron beam was recorded photographically on a 40 cm bent crystal spectrograph of the Cauchois-type. Three new satellites were observed at 1.7747, 1.7691, and 1.7634 Å (1 Å = 10−10 m). These are identified as α5, α6, and α7, respectively, and assigned mainly to the 2D5/2 – 2D5/2, 2P3/2 – 2D5/2, and 2P1/2 – 2D3/2 transitions, respectively, of 1s−12p−2 – 2p−3 array.
Exploratory investigation of color changes in paints induced by broadband synchrotron radiation
Authors: Bawagan A. D. O. , Sabaye-Moghaddam M. , Tan K. H. , Yates B. W.
Published: December 2010

Changes in color of coated (painted) aluminum surfaces exposed to broad-band synchrotron radiation (10–2000 eV) are investigated as a function of radiation dose (N). Quantitative color differences [Formula: see text] before and after exposure are obtained from spectral diffuse reflectance measurements using the standard CIELAB formula. The results indicate that the dose–response curve of the color-coated surfaces at large photon doses can be described as [Formula: see text] where d is a material-dependent constant.
Use of a double-spike to determine the half-life of 39Ar and the operating characteristics of a mass spectrometer used in geochronological studies
Authors: Baksi Ajoy K. , Archibald D. A. , Farrar Edward
Published: December 2010

A double-spike, containing 36Ar, 38Ar, 39Ar, and 40Ar, was used to investigate the operating characteristics of an 40Ar/39Ar dating system. Analyses conducted whilst the (MS10) mass spectrometer yielded 40Ar/36Ar ratios for atmospheric argon differing by ~4%, indicate the mass discrimination for intermediate isotopes is linear in nature. Runs utilizing a fraction of the spike confirm the validity of a theoretical orifice correction factor. In conjunction with earlier analyses on the double spike, we report a mass spectrometrically determined half-life for 39Ar of 276 ± 3 a, ~3% greater than derived from disintegration rates.
Derivative expansion for the one-loop effective Lagrangian in QED
Authors: Gusynin V. P. , Shovkovy I. A.
Published: December 2010

The derivative expansion of the one-loop effective Lagrangian in QED4 is considered. The first term in such an expansion is the famous Schwinger result for a constant electromagnetic field. In this paper we give an explicit expression for the next term containing two derivatives of the field strength Fμν. The results are presented for both fermion and scalar electrodynamics. Some possible applications of an inhomogeneous external field are pointed out.
X-ray absorption fine structure of Terfenol-D as a function of magnetic field
Authors: Bonin Y. R. , Crozier E. D.
Published: December 2010

Terfenol-D (Tb0.3Dy0.7Fe2) has a giant magnetostrictive effect with a saturation strain of 1.1 × 10−3. Possible structural changes due to an applied magnetic field and as a function of temperature are examined by a polarization-dependent extended X-ray absorption fine structure study at two temperatures above and below the spin reorientation temperature, Ts = 10 °C, at two applied magnetic fields, B = 0 and 5.5 kG, and at two edges, the Fe K edge and the Dy LIII edge. To within ±0.003 Å (1 Å = 10−10 m) no internal distortion of the unit cell was observed.
On atomic squeezing in a generalized multiphoton Jaynes–Cummings model
Authors: Xie Rui-Hua
Published: December 2010

Dynamical evolution of atomic squeezing is studied in a generalized multiphoton Jaynes–Cummings model. The influence of some nonlinear interactions and the counter-rotating wave term on the squeezing is discussed in detail. These nonlinear interactions influence the squeeze duration and its revival period. In a multiphoton transition, switching on the counter-rotating wave term has a much more destructive effect on the squeezing, but this destructive effect is weakened due to the presence of a nonlinear Kerr-like medium.
A study of electroconvection in the presence of a gravitational field
Authors: Haque M. F. , Arajs Sigurds
Published: December 2010

Measurements were made of the electroconvective heat transfer coefficient in gases (Ar, O2, N2O, and Freon-22); liquid (distilled water); and a colloidal suspension (α-Fe2O3 in distilled water) from a single Pt wire (diameter = 0.025 mm) mounted along the axis of a Cu cylinder (diameter = 53 mm). The measurements were carried out as functions of electric fields (dc and ac) and pressure in the Earth's gravitational field. The measurements reveal a complicated interaction between the electric-field gradient and thermal convection. Measured heat-transfer data are correlated by dimensional analysis. The data are compared with the empirical correlation relation and analytical expression and are well correlated over the range of Rayleigh numbers from 1.2 × 107 to 4.5 × 108. An empirical correlation relation has, also been proposed to evaluate the efficiency of convection and the results for dc and ac fields are presented.
Interaction of light with a lattice of dipoles: substrate-related effects
Authors: Dormale Bernard M. de
Published: December 2010

We present a very easy way to take into account exactly the effect of a substrate for a two-dimensional lattice of spheres subject to dipole–dipole interaction. Comparison with experiment shows better agreement than when other dipole treatments are used.
A functional approach to loop diagrams
Authors: McKeon D. G. C.
Published: December 2010

A closed-form expression for the N-loop contribution to the generating functional can be written down using the heat kernel [Formula: see text]. If [Formula: see text] where Aμ and V are functions of the background field, then by using quantum-mechanical techniques, this heat kernel can be expanded in powers of the background field, allowing one to compute Green's functions. We demonstrate that one can also employ to this end a distinct functional approach developed by Onofri, which circumvents both loop-momentum integrals and the quantum-mechanical path integral. We illustrate the technique by computing the two-point function in scalar electrodynamics to one-loop order.
Acoustic wave scattering from a randomly rough surface
Authors: Mudaliar S.
Published: December 2010

Acoustic wave scattering from a randomly rough surface is studied using a multiple scattering analysis. Assuming the surface asperities to be small, approximate boundary conditions are used to derive a pair of coupled integral equations for the velocity potentials. The Dyson equation is next derived on introducing symbolic operators. Using the bilocal approximation the Dyson equation is solved, thereby obtaining explicit expressions for the coherent reflection and transmission coefficients. The analysis is similarly carried on further to compute the incoherent intensity by using the ladder approximation, and hence an expression for the scattering coefficient is obtained.
The motion of a curling rock
Authors: Shegelski Mark R. A. , Niebergall Ross , Walton Mark A.
Published: December 2010

We present a plausible physical model that accounts for the motion of a curling rock. The principal features of the model are (i) that the kinetic friction induces melting of the ice with the consequence that the curling rock experiences both "dry friction," when encountering solid ice, as well as "wet friction," for contact areas that pass over the thin film of liquid water lying above the ice; (ii) that the wet friction is velocity dependent; and (iii) that the curling rock is able, in its last stages of motion, to drag some of the thin liquid film part way around the rock, which significantly enhances the curl of the rock. We compare the model to actual trajectories of curling rocks.
The effect of loading Gregorian antennas on side-lobe levels
Authors: Afacan Erkan , Yazgan Erdem
Published: December 2010

E- and H -plane radiation patterns of focus-fed, axially symmetric Gregorian antennas are analyzed using the generalized method of the geometrical theory of diffraction. Only the rim of the main reflector was loaded, in a smoothly tapered manner, but the whole surface of the subreflector was loaded. Loads are defined in terms of surface impedances. With the help of this analysis, the effect of the smoothly tapered rim loading on the far-field radiation patterns of Gregorian antennas can be studied in detail.
Effect of coupling strength on the intermodulation distortion in DFB laser
Authors: Anis Hanan , Goodwin J. , Makino T. , Xu J. M.
Published: December 2010

In this work the effect of increasing the coupling strength on the intermodulation distortion is investigated. It is shown that only if other effects such as the change in the relaxation oscillation are absent, higher coupling strength leads to a higher intermodulation distortion. Otherwise, the dependence of distortion on the coupling strength is not monotonic and exhibits trends in the mid- and high-frequency regimes that are very different from that in the low-frequency regime.
Thermally activated current–voltage asymmetry in quantum-well inter-subband photodetectors
Authors: Kolev P. V. , Deen M. J. , Liu H. C. , Li Jianmeng , Buchanan M. , Wasilewski Z. R.
Published: December 2010

Continuing research interest in quantum-well inter-subband-based devices can be associated with its prospects for numerous optoelectronic applications in the long wavelength infrared region. This paper presents experimentally measured field dependence of the thermally activated effective-barrier lowering in quantum-well inter-subband photodetectors (QWIPs). This barrier lowering is considered to be the main cause of the commonly observed asymmetry in the current–voltage characteristics of QWIPs. The research results presented here are important for understanding the factors determining the dark-current mechanisms that are crucial for further improvement in the characteristics of these devices. The study of current-carrier transport phenomena in a quantum well is also of interest for developing quantum-well lasers and avalanche photodetectors based on intraband processes, and also transistors based on ballistic or hot carrier transport phenomena.
A three-terminal N-channel InGaAsP–InP-based double heterostructure optoelectronic switch (DOES)
Authors: Tan E. , Simmons J. G. , Thompson D. A. , Blaauw C.
Published: December 2010

In this work, we give the first report on the physical and functional characteristics of a three-terminal InGaAsP–InP-based double heterostructure optoelectronic switch (DOES) device. In this device, electrical contact is made to the emitter, collector, and active layers while optical input is made via a window in the emitter contact. The DC current–voltage characteristic of a 100 μm × 80 μm device exhibits a switching voltage of 6.6 V with an OFF-state resistance of 200 kΩ and an ON-state resistance of <50 Ω. In conjunction with the electrical outputs, optical emission is generated with a ratio of >10 in the light emission between the ON (2 mA) and OFF states. We show that injection of current and (or) injection of light into the active region reduces the switching voltage. This is used to switch the device from the OFF state to the ON state without having to alter the output circuit bias (emitter–collector bias). The ability to switch the three-terminal InGaAsP–InP DOES with both electrical and optical inputs demonstrate its functionality, flexibility, and suitability for use in optoelectronic switching applications and for InP-based optoelectronic integrated circuits.
The effect of field-interference in modelling gain-coupled DFB lasers
Authors: Lee K. , Anis H. , Xu J. M. , Makino T. , Xu J. M.
Published: December 2010

Transfer matrix method models for distributed feedback (DFB) lasers have generally neglected the effects of field interference, presumably, because of the computational complexity of the problem. Instead, the forward- and backward-propagating components of the field are treated as independent and the interference considerations are averaged out. These models are inappropriate for gain-coupled DFB structures, where the gain material distribution in the device varies significantly over spatial distances on the order of the wavelength of light and the details of spatial distribution of the longitudinal photon density becomes crucial. In this paper the consequences of considering the spatial distribution of the photon density due to the interference between the counter-propagating components of the field are presented using a new photon rate equation. The results from this more involved and more accurate calculation show that the effective coupling strength of a laser is larger than that predicted from previous averaged models.
Intersecting rib waveguide structures with reduced crosstalk
Authors: Daly M. G. , Jessop P. E. , Yevick D.
Published: December 2010

A numerical study of the throughput and crosstalk in intersecting semiconductor rib waveguides was carried out using the beam propagation method. The fraction of the optical power that couples out of one input waveguide and into the crossed waveguide falls to below 3% for crossing angles greater than 4°. Two simple modifications to the waveguide shape at the X-crossing region were found to reduce the crosstalk for crossing angles between 4° and 10° such that the crosstalk to throughput ratio may be reduced by up to a factor of 100 while the throughput is reduced by, at most, a few percent. In device structures that combine X-crossings with curved waveguide sections our results permit greater design flexibility and improved overall loss and crosstalk performance.
Monolithic integration of metal-semiconductor-metal (MSM) photodetectors and optical waveguides: The use of polyimide waveguides for optical signal distribution
Authors: Robitaille Lucie , Callender Claire L. , Noad Julian P.
Published: December 2010

Straight and curved polyimide waveguides have been fabricated for on-chip optical signal distribution. The optical properties of the structures at 633 and 830 nm are presented. The potential of polyimide waveguides for monolithic integration with GaAs MSM photodetectors is discussed.
Electrical isolation of pin photodiode devices by oxygen ion bombardment
Authors: Akano U. G. , Mitchell I. V. , Shepherd F. R. , Miner C. J. , Margittai A. , Svilans M.
Published: December 2010

Using the Hall-effect measurements, the resistance changes in Si-doped (5 × 1017 cm−3), 1 μm thick epilayers of InGaAs and in InP/InGaAs pin structures were studied as functions of multiple-energy oxygen ion dose, implant temperature (−196 and 18 °C), and rapid thermal-anneal (RTA) temperatures. In the case of InGaAs epilayers, the peak resistivity is attained following post-implant RTA at 400–500 °C, with samples implanted at −196 °C exhibiting at least a factor of 10 larger resistivity than those implanted at 18 °C (106 vs. 105 Ω/⁪). The thermal stability of the induced resistivity is also dependent on the implant temperature and the ion dose. The results suggest that for InGaAs layers, sheet resistances in excess of 106 Ω/⁪, stable to temperatures in excess of the anticipated pin device processing temperatures, can be produced by 16O ion implantation. The use of O ion bombardment to produce planar, implant-isolated pin photodiodes with excellent dark-current and frequency response characteristics has been demonstrated.
Determination of growth parameters for atomic layer epitaxy using reflectance difference spectroscopy
Authors: Arès R. , Tran C. A. , Watkins S. P.
Published: December 2010

Reflectance difference spectroscopy (RDS) has been used to monitor the anisotropy of the surface of InAs and GaAs grown by atomic layer epitaxy (ALE). Saturation of the RDS signal is observed when the surface is fully covered with one monolayer of the impinging surface species. This property is used to optimize the growth interruptions for the ALE cycle. Good correlation of the RDS saturation is observed with growth-rate measurements obtained by X-ray diffraction (XRD). When exposure times are sufficiently long for saturation to be observed in the RDS signal, a growth rate of one monolayer per cycle (1 ML/cycle) is achieved. In principle all the different growth parameters such as exposure and purge times as well as gas flows can be determined in a few cycles performed on a single substrate. Without RDS the same results would require several growth runs and time consuming X-ray characterization.
Passivation of the SiNx/GaAs (110) interface
Authors: Huang L. J. , Rajesh K. , Lau W. M. , Landheer D. , Baribeau J. -M. , Ingrey S.
Published: December 2010

Passivation of the SiNx/GaAs (110) interface was performed with different surface treatments including sulphur passivation and a Si or Si/Ge interface control layer on sulphur-passivated surfaces prior to silicon nitride deposition. The interface state density was measured with capacitance–voltage (CV) measurements of metal–insulator–semiconductor capacitors fabricated on the passivated surfaces using remote plasma-deposited silicon nitride as the gate insulator. The interface structures of the capacitors were analyzed by X-ray reflectivity and X-ray photoemission spectroscopy. It was found that the Si/Ge/S multilayer passivation approach led to the best CV results for an n-type substrate. The results also show that sulphur passivation could suppress As(Ga) segregation and that the interfacial atomic structure was not the only factor that determines the passivation. By comparing the quasi-static and high-frequency (1 MHz) CV data, we found that the minimum interface state density of the fabricated capacitors made on n-type substrates was about 1012 eV−1 cm−2.
Metalorganic vapor phase epitaxy and structural characterization of InP on Si(111)
Authors: Ababou Y. , Desjardins P. , Masut R. A. , Yelon A. , L'Espérance G.
Published: December 2010

We report the growth of InP layers using low-pressure metalorganic vapor phase epitaxy on buffered HF-treated Si(111) surfaces, both normally oriented and 3.8° off, toward [Formula: see text]. The InP layers grown on normally oriented Si(111) show the presence of roughly regular terraces, which may be associated with antiphase domains, whose width increases rapidly with the epilayer thickness. The average dislocation density at the top surface is as low as 4 × 105 cm−2 for 4.8 μm thick epilayers. Transmission electron microscopy observations show a rapid decrease of threading dislocation densities with increasing distance from the interface, due principally to their coalescence, as determined from X-ray diffraction analysis. This indicates a high reaction constant between dislocations, of 1.8 × 10−5 cm.
Microsensors for physical signals: Principles, device design, and fabrication technologies
Authors: Nathan Arokia
Published: December 2010

Microsensors are miniaturized devices, fabricated using silicon-based and related technologies, that convert input physical and chemical signals into an output electrical signal. The key driving force in microsensor research has been the integrated circuit (IC) and micromachining technologies. The latter, in particular, is fueling tremendous activity in micro-electromechanical systems (MEMS). In terms of technology and design tools, MEMS is at a stage where microelectronics was 30 years ago and is expected to evolve at an equally rapid pace. The synergy between the IC, micromachining, and integrated photonics technologies can potentially spawn a new generation of microsystems that will feature a unique marriage of microsensor, signal-conditioning and -processing circuitry, micromechanics, and optomechanics possibly on a single chip. In this paper, the physical transduction principles, materials considerations, process-fabrication technologies, and computer-aided-design (CAD) tools will be reviewed along with pertinent examples drawn from our microsensor research activity at the Microelectronics Laboratory, University of Waterloo.
Magnetic pattern recognition sensor arrays using CCD readout
Authors: O Nixon , Nathan Arokia
Published: December 2010

A magnetic sensor array has been designed to overcome the limitations of technologies currently employed in the retrieval of magnetically encoded information. The array is reminiscent of a linear photodiode CCD, with the exception that the photodiodes have been replaced by buried-channel MOS magnetic sensors. The use of buried-channel MOS sensor elements results in lower noise and higher sensitivity. Noise is lower because of the absence of carrier-oxide interaction. Sensitivity, a parameter proportional to Hall mobility, is enhanced because of the absence of surface scattering. Sensitivity is further enhanced by employing multiple-gate structures, which exploit the dependence of Hall mobility on electric field to increase magnetic sensitivity. Characterization and numerical modelling results of the noise and sensitivity properties of the MOS sensor element are presented.
A novel n+-polysilicon on n-silicon iso-type diode
Authors: Mohajerzadeh S. , Selvakumar C. R.
Published: December 2010

We report the results of fabricating n+-n iso-type diodes using in-situ phosphorus–doped polysilicon films on n-type 1 Ω cm <100> Si substrates. The electrical characteristics of this structure give evidence of the presence of an energy barrier at the film–substrate interface reminiscent of Schottky-barrier diodes. The current–voltage characteristics show exponential behavior over three decades of current. An ideality factor of 1.2 is extracted from the experimental results. An energy barrier height of about 0.2 eV is obtained from the current–temperature analysis.
Unique dc characteristics of a new gated lateral pnp bipolar junction transistor (BJT) using 0.8 μm BiCMOS technology
Authors: Deen M. J. , Yan Z. X.
Published: December 2010

In this paper, the detailed device dc performance of a gated lateral pnp (LPNP) device that has five terminals, collector C, base B, emitter E, gate G, and substrate S, and is fabricated in a 0.8 μm BiCMOS technology is described. Because this gated LPNP has two inputs and one output, it shows unique dc characteristics of variable current gain, βF, of 102 ~ 104 with VG variations of 0.4 to – 0.4 V; variable transconductance, gM, which increases 3 ~ 10 times as VE increases from 0.4 to 0.7 V. Based on these unique features, this new device is attractive for some analog circuit applications; for example, when used as a mixer, it has a conversion gain of 5–12 dB for an input RF signal up to 400 MHz.
SYNTHESIS AND CHARACTERIZATION OF NANOPARTICLES OF CALCIUM PYROPHOSPHATE
Authors: VASANT SONAL R. , JOSHI M. J.
Published: December 2010

Calcium phosphate based biomaterials play important roles in clinical applications. Calcium pyrophosphate (CPP), a kind of calcium phosphate, can be used as a bone substitution material as well as a bone graft. Because of its similarity to inorganic component of bone and teeth it can be used for surface coating of metallic dental and orthopedic implants. In the present study, calcium pyrophosphate dihydrate (CPPD) nanoparticles were synthesized using surfactant mediated approach. Crystalline nature and average crystallite size was studied using Powder XRD. The CPPD nanocrystallites were found to be triclinic from powder XRD. The TEM study indicated that CPPD nanoparticles were in the range of 13 nm to 20 nm. The presence of various bonds was confirmed by FTIR spectroscopy. The amount of water of hydration and the thermal stability was studied by thermogravimetry. The variations of various dielectric parameters with the frequency of applied field in 3.2 kHz to 32 MHz range and within a temperature range from 60°C to 120°C were studied. The formation of other phases such as β-CPP and α-CPP on heating of CPPD at 900°C and 1250°C, respectively, were studied by the Powder XRD. The results are discussed.
ULTRASONIC VELOCITY AND OXYGEN-RELATED ELASTIC ANOMALIES IN Zn2+-SUBSTITUTED (Dy,Ca)Ba2Cu3-yZnyO7-δ SUPERCONDUCTORS
Authors: RASIH N. A. , YAHYA A. K. , YUSOF M. I.
Published: December 2010

Ultrasonic longitudinal velocity measurements between 80 K and 280 K and shear velocity measurements between 80 K and 230 K have been performed in polycrystalline superconducting DyBa 2 Cu 3-x Zn x O 7-δ (x = 0, 0.01 and 0.03) and Dy 0.9 Ca 0.1 Ba 2 Cu 3-y Zn y O 7-δ (y = 0.01) samples utilizing the pulsed-echo-overlap technique. A longitudinal anomaly characterized by a step-like slope change was observed at around 240 K for DyBa 2 Cu 3-x Zn x O 7-δ (x = 0) and at 230 K for x=0.01 and 0.03. Zn 2+ substitution suppressed critical temperature, Tc but did not suppress the step-like anomaly. On the other hand, substitution of Ca 2+ in Dy 0.9 Ca 0.1 Ba 2 Cu 3-y Zn y O 7-δ (y = 0.01) caused the step-like anomaly to disappear. The step-like anomaly was suggested due to the oxygen-ordering process in Cu – O chains during a phase transition process at low temperatures. Substitution of Zn 2+ ions in place of Cu was suggested to go into CuO 2 planes and did not interfere with oxygen-ordering in Cu – O chains. This is suggested as the reason why the step-like anomalies were not suppressed in DyBa 2 Cu 3-x Zn x O 7-δ (x = 0.01 and 0.03) samples. Disappearance of the step-like anomaly due to Ca 2+ substitution is probably related to reduction in oxygen content which depletes Cu – O chain sites.
FLUCTUATION OF MESOSCOPIC RLC CIRCUIT AT PHOTON-SUBTRACTED AND PHOTON-ADDED THERMO VACUUM STATES WITH FINITE TEMPERATURE
Authors: XU XUE-XIANG , HU LI-YUN , FAN HONG-YI
Published: December 2010

By using the Wigner function to evaluate expectation values of any symmetrically order of operator in a classical fashion, we study the quantum fluctuation and the uncertainty relation of mesoscopic RLC circuit at photon-subtracted and photon-added thermo vacuum states. It is found that the fluctuations and the uncertainty relation of both charge and current are linearly related to the photon-subtracted and photon-added number.
THE COMPLEXITY OF BROWNIAN PROCESSES RUN WITH NONLINEAR CLOCKS
Authors: PARK MOONGYU , CUSHMAN JOHN H.
Published: December 2010

Anomalous diffusion occurs in many branches of physics. Examples include diffusion in confined nanofilms, Richardson turbulence in the atmosphere, near-surface ocean currents, fracture flow in porous formations and vortex arrays in rotating flows. Classically, anomalous diffusion is characterized by a power law exponent related to the mean-square displacement of a particle or squared separation of pairs of particles: 〈|X(t)|2〉 ~tγ. The exponent γ is often thought to relate to the fractal dimension of the underlying process. If γ > 1 the flow is super-diffusive, if it equals 1 it is classical, otherwise it is sub-diffusive. In this work we illustrate how time-changed Brownian position processes can be employed to model sub-, super-, and classical diffusion, while time-changed Brownian velocity processes can be used to model super-diffusion alone. Specific examples presented include transport in turbulent fluids and renormalized transport in porous media. Intuitively, a time-changed Brownian process is a classical Brownian motion running with a nonlinear clock (Bm-nlc). The major difference between classical and Bm-nlc is that the time-changed case has nonstationary increments. An important novelty of this approach is that, unlike fractional Brownian motion, the fractal dimension of the process (space filling character) driving anomalous diffusion as modeled by Bm-nlc positions or velocities does not change with the scaling exponent, γ.
A NEW TUNABLE FLOATING CMOS FDNR AND ELLIPTIC FILTER APPLICATIONS
Authors: KAÇAR FIRAT
Published: December 2010

A new tunable CMOS FDNR circuit is proposed. The circuit is based on the transcapacitive gyrator approach with both transcapacitive stages realized by MOS transistors configuration. This FDNR element lends itself well to the design of low-pass ladder filters and its use will result in a more efficient integrated circuit implementation than filters that simulate floating inductors utilizing resistive gyrators. The applications of FDNR to realize a current-mode fifth-order elliptic filter and current mode sixth-order elliptic band-pass filter are given. The proposed FDNR is simulated using CMOS TSMC 0.35 μm technology. Simulation results are given to confirm the theoretical analysis.
REDUCING THE ENERGY DISSIPATION OF THE ISSUE QUEUE BY EXPLOITING NARROW IMMEDIATE OPERANDS
Authors: KAYNAK İLKNUR CANSU , KOÇBERBER YUSUF ONUR , ERGİN OĞUZ
Published: December 2010

In contemporary superscalar microprocessors, issue queue is a considerable energy dissipating component due its complex scheduling logic. In addition to the energy dissipated for scheduling activities, read and write lines of the issue queue entries are also high energy consuming pieces of the issue queue. When these lines are used for reading and writing unnecessary information bits, such as the immediate operand part of an instruction that does not use the immediate field or the insignificant higher order bits of an immediate operand that are in fact not needed, significant amount of energy is wasted. In this paper, we propose two techniques to reduce the energy dissipation of the issue queue by exploiting the immediate operand files of the stored instructions: firstly by storing immediate operands in separate immediate operand files rather than storing them inside the issue queue entries and secondly by issue queue partitioning based on widths of immediate operands of instructions. We present our performance results and energy savings using a cycle accurate simulator and testing the design with SPEC2K benchmarks and 90 nm CMOS (UMC) technology.
ADAPTIVE PIPELINE VOLTAGE SCALING IN HIGH PERFORMANCE MICROPROCESSOR
Authors: YEH CHANG-CHING , CHANG KUEI-CHUNG , CHEN TIEN-FU , YEH CHINGWEI
Published: December 2010

Deep pipeline has traditionally been widely used in high performance microprocessor. To allow continuous program execution, branch prediction provides a necessary method of speculatively executing instructions without compromising performance. However, branch misprediction penalty significantly impacts the performance of the deep pipeline processor. This study presents a new Adaptive Pipeline Voltage Scaling (APVS) technique to reduce branch misprediction penalty. For a likely mispredicted branch entering the processor, APVS begins increasing voltage and merging deep pipeline whereby shorter pipeline length permits less branch misprediction penalty. Once the branch is resolved, the merged stages are split and the supply voltage is reduced again. With dedicated shorter pipeline length within each branch misprediction, APVS achieves great performance improvement. The evaluation of APVS in a 13-stage superscalar processor with benchmarks from SPEC2000 applications shows a performance improvement (between 3–12%, average 8%) over baseline processor that does not exploit APVS.
FET SMALL-SIGNAL MODELING USING MEL-FREQUENCY CEPSTRAL COEFFICIENTS AND THE DISCRETE COSINE TRANSFORM
Authors: ELSHARKAWY R. R. , HINDY M. , EL-RABAIE S. , DESSOUKY M. I.
Published: December 2010

In this paper, a novel neural technique is proposed for FET small-signal modeling. This technique is based on the discrete cosine transform (DCT) and the Mel-frequency cepstral coefficients (MFCCs). The input data to traditional neural systems for FET small-signal modeling are the scattering parameters and the corresponding frequencies in a certain band, and the outputs are the circuit elements. In the proposed technique, the input data are considered random, and the MFCCs are calculated from these inputs and their DCT. The MFCCs are used to give a few features from the input random data sequence to be used for the training of the neural networks. The objective of using MFCCs is to characterize the random input sequence with features that are robust against measurement errors. The MFCCs extracted from the DCT of the inputs increase the robustness against measurement errors. There are two benefits that can be achieved using the proposed technique; a reduction in the number of neural inputs and hence a faster convergence of the neural training algorithm and a robustness against measurement errors in the testing phase. Experimental results show that the technique based on the DCT and MFCCs is less sensitive to measurement errors than using the actual measured scattering parameters.
FUZZY SUPERVISED NONLINEAR PID CONTROL OF A CLASS OF UNKNOWN NONLINEAR SYSTEMS
Authors: REKIK L. TOUNSI , CHTOUROU MOHAMED
Published: December 2010

Fuzzy control has been successfully applied in many cases to which conventional control algorithms are difficult to be applied. Recently, it was proven that fuzzy systems are capable of approximating any real continuous function to arbitrary accuracy. This result motivates us to use the fuzzy identifiers for nonlinear dynamic systems and then design the fuzzy supervised nonlinear PID controller based on the fuzzy system. There are two main objectives in this paper: (1) We use the Takagi and Sugeno's fuzzy models as an identifier for nonlinear dynamic systems, and derive the identification algorithm, (2) the fuzzy supervisor design method for tracking control is proposed based on this fuzzy system. In order to improve the dynamic response of the closed loop fuzzy model, the optimization of the performance of the fuzzy supervisor will be considered.

To prove the potential applications of the proposed strategy, simulation was carried out for the speed control of a DC motor with serial excitation and a first order nonlinear process.
A NOVEL FEATURE EXTRACTION SCHEME FOR HUMAN GAIT RECOGNITION
Authors: NASSAR HAMED , EL-TAWEEL GHADA , MAHMOUD EMAN
Published: December 2010

With the increasing demand of visual surveillance systems, human recognition at a distance has gained extensive research interest. Gait is a potential behavioral feature to identify humans based on their motion. This paper describes a new scheme for extracting and selecting features from the gait of a human for recognition. The scheme combines both Key Fourier Descriptors (KFDs) and principal component analysis (PCA) techniques. This leads to a strength in reducing feature space by KFD, and increasing accuracy by PCA. Also, it is shown that the proposed scheme leads to a higher correct classification rate than schemes that depend on KFD alone or PCA alone.
STEGANOGRAPHIC SCHEME FOR GRAY-LEVEL IMAGE USING PIXEL NEIGHBORHOOD AND LSB SUBSTITUTION
Authors: DHARWADKAR NAGARAJ V. , AMBERKER B. B.
Published: December 2010

The exchange of secret message using images has vital importance in secret communication. Steganographic scheme is employed to achieve the task of secret message communication using images. The existing scheme based on pixel value differencing (PVD) with least significant bit (LSB) sequential substitution suffer from low embedding capacity. The embedding capacity is increased by using the edge regions of image obtained by neighborhood connectivity of pixel. We propose an adaptive steganographic scheme for gray-level images. Our scheme relies on the neighborhood connectivity of pixels to estimate the embedding capacity and resolves the problem of sequential substitution by jumbling the bits of secret message. The effect of cropping and filtration attacks on stegoimage is minimized by embedding the copies of secret message into four different regions of the cover image. The performance of the scheme is analyzed for various types of image processing attacks like cropping, blurring, filtering, adding noise, and sharpening. The proposed scheme is found rigid to these attacks.
COLLABORATION STRUCTURE AND PERFORMANCE IN NEW SOFTWARE DEVELOPMENT: FINDINGS FROM THE STUDY OF OPEN SOURCE PROJECTS
Authors: COLAZO JORGE A.
Published: December 2010

The state of software development performance is far from being exemplar, with a success rate well below that of other industries, and understanding how to improve these projects is not only substantive but urgent. Software development is at most times a collaborative effort, yet we do not understand clearly how different collaboration structures associate with development performance metrics. This paper empirically examines the association between collaboration patterns, project productivity and product quality through a field study of working software open source new product development teams, using archival data from electronic sources related to Open Source Software projects. Collaboration structures are measured using Social Network Analysis and in terms of their network density, network centralization and the level of boundary spanning activity of team members. Productivity and quality are measured using "hard", code-based metrics. Results of regression analyses testing relevant hypotheses suggest that project managers need to strongly encourage internal collaboration, but be wary of allowing team members to participate in multiple projects. The breadth of skills within the team is a tactical asset that may increase the efficient frontier in the quality–productivity trade-off. Results also show that centralized structures associate with higher product quality and development productivity.
RISK TAKING, INNOVATIVENESS AND COMPETITIVE RIVALRY: A THREE-WAY INTERACTION TOWARDS FIRM PERFORMANCE
Authors: GIBB JENNY , HAAR JARROD M.
Published: December 2010

It is unclear how entrepreneurial firms should engage in risk taking and innovativeness in highly competitive environments. Using a sample of 167 New Zealand firms, we provide new insight to identify a significant three-way interaction effect between risk taking, innovativeness and competitive rivalry towards firm performance. We found high risk taking and innovativeness to be linked to higher firm performance, irrespective of the extent of competitive rivalry. Low innovativeness was found to be associated with differing levels of firm performance depending on the level of rivalry. These results have important implications for future research and for practitioners where competitive rivalry can influence dimensions of performance in entrepreneurial firms in ways that have not been previously recognized.
INTERNET-BASED TECHNOLOGY USE AND NEW PRODUCT TIME-TO-MARKET: THE MODERATING EFFECT OF PRODUCT INNOVATIVENESS
Authors: DE GROSBOIS DANUTA , KUMAR UMA , KUMAR VINOD
Published: December 2010

The aim of this study is to investigate the impact of Internet-based technology (IBT) use during a new product development (NPD) project on new product time-to-market. It is hypothesized that (1) IBT use has a positive impact on new product time-to-market (2) this impact is both direct and indirect (3) the indirect impact of IBT use on product time-to-market is achieved through improvement of communication quality, effectiveness of team learning and level of team integration (4) the strength of these relationships is moderated by the product innovativeness. In order to test the hypotheses, data from 278 NPD projects conducted by Canadian and American manufacturing companies were collected and analyzed. IBT use was found to be a significant contributor to communication quality, effectiveness of team learning, level of team integration and new product time-to-market. Additionally, the results indicate that the relationships are stronger for projects developing highly innovative products as opposed to less innovative products.
Native and Exotic Pests ofEucalyptus: A Worldwide Perspective
Authors: Paine Timothy D. , Steinbauer Martin J. , Lawson Simon A.
Published: December 2010

Eucalyptus species, native to Australia, Indonesia, the Philippines, and New Guinea, are the most widely planted hardwood timber species in the world. The trees, moved around the globe as seeds, escaped the diverse community of herbivores found in their native range. However, a number of herbivore species from the native range of eucalypts have invaded many Eucalyptus-growing regions in North America, Europe, Africa, Asia, and South America in the last 30 years. In addition, there have been shifts of native species, particularly in Africa, Asia, and South America, onto Eucalyptus. There are risks that these species as well as generalist herbivores from other parts of the world will invade Australia and threaten the trees in their native range. The risk to Eucalyptus plantations in Australia is further compounded by planting commercially important species outside their endemic range and shifting of local herbivore populations onto new host trees. Understanding the mechanisms underlying host specificity of Australian insects can provide insight into patterns of host range expansion of both native and exotic insects.
Recent Insights from Radar Studies of Insect Flight
Authors: Chapman Jason W. , Drake V. Alistair , Reynolds Don R.
Published: December 2010

Radar has been used to study insects in flight for over 40 years and has helped to establish the ubiquity of several migration phenomena: dawn, morning, and dusk takeoffs; approximate downwind transport; concentration at wind convergences; layers in stable nighttime atmospheres; and nocturnal common orientation. Two novel radar designs introduced in the late 1990s have significantly enhanced observing capabilities. Radar-based research now encompasses foraging as well as migration and is increasingly focused on flight behavior and the environmental cues influencing it. Migrant moths have been shown to employ sophisticated orientation and height-selection strategies that maximize displacements in seasonally appropriate directions; they appear to have an internal compass and to respond to turbulence features in the airflow. Tracks of foraging insects demonstrate compensation for wind drift and use of optimal search paths to locate resources. Further improvements to observing capabilities, and employment in operational as well as research roles, appear feasible.