bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of ionic strength on surfactant-induced unsaturated flow
Authors: Bashir Rashid , Smith James E. , Stolle Dieter E.
Published: April 2011

The effect of ionic strength of soil water on surfactant-induced unsaturated flow is investigated for the anionic surfactant DOWFAX 8390. Instrumented infiltration experiments were performed to study the impact of surfactant and ionic strength of the soil-water solution on unsaturated flow. A solution having a measured surface tension of 68 mN/m was prepared with 0.014% w/w DOWFAX using distilled water and applied to the soil column instrumented with time domain reflectometry probes and pressure transducer equipped tensiometers. Results of the experiment were compared with those of pure water to investigate surfactant-induced flow and the corresponding influence of the ionic strength of soil water. The DOWFAX solution behaved like a solution having a surface tension of 49 mN/m, which was directly attributed to the interaction between the surfactant and soil water. Soil-moisture characteristic curves for soil wetted with water and DOWFAX were also measured, and a scaling relationship as a function of reduced surface tension is proposed.
ELECTRONIC STRUCTURE AND OPTICAL PROPERTIES OF A PHOTOLUMINESCENT TANTALITE: EuKNaTaO5
Authors: ZHANG XIAOLI , ZHANG GUOREN , JIA TING , GUO YING , ZENG ZHI
Published: April 2011

The electronic structure and linear optical properties of luminescent material EuKNaTaO5 are investigated by employing full-potential linear augmented plane wave method. Our results show highly localized Eu 4f states which pinned in the energy range below the unoccupied Ta 5d states and over the occupied O 2p states. The optical spectra are analyzed and interpreted in terms of the electronic structure. It is found that Eu ions absorb the major parts of the incident energy below 3.3 eV. This is in accordance with the experimental result that EuKNaTaO5 phosphor is efficient under the excitation of 535 nm (2.3 eV) visible part of the spectrum. The linear optical properties are found to be anisotropic.
EVALUATING CUMULATIVE ASCENT: MOUNTAIN BIKING MEETS MANDELBROT
Authors: RAPAPORT D. C.
Published: April 2011

The problem of determining total distance ascended during a mountain bike trip is addressed. Altitude measurements are obtained from GPS receivers utilizing both GPS-based and barometric altitude data, with data averaging used to reduce fluctuations. The estimation process is sensitive to the degree of averaging, and is related to the well-known question of determining coastline length. Barometric-based measurements prove more reliable, due to their insensitivity to GPS altitude fluctuations.
NUMERICAL TREATMENT OF ROTATING NEUTRON STARS SIMULATED BY GENERAL-RELATIVISTIC POLYTROPIC MODELS: A COMPLEX-PLANE STRATEGY
Authors: GEROYANNIS V. S. , SFAELOS I. E.
Published: April 2011

We solve numerically in the complex plane all the differential equations involved in Hartle's perturbation method for computing general-relativistic polytropic models of rotating neutron stars. We give emphasis on computing quantities describing the geometry of models in rapid rotation. Compared to numerical results obtained by certain sophisticated iterative methods, we verify appreciable improvement of our results vs to those given by the classical Hartle's perturbative scheme.
SEESAW AT LHC THROUGH LEFT–RIGHT SYMMETRY
Authors: SENJANOVIĆ GORAN
Published: April 2011

I argue that LHC may shed light on the nature of neutrino mass through the probe of the seesaw mechanism. The smoking gun signature is lepton number violation through the production of same sign lepton pairs, a collider analogy of the neutrinoless double beta decay. I discuss this in the context of left–right symmetric theories, which led originally to neutrino mass and the seesaw mechanism. A WR gauge boson with a mass in a few TeV region could easily dominate neutrinoless double beta decay, and its discovery at LHC would have spectacular signatures of parity restoration and lepton number violation. Moreover, LHC can measure the masses of the right-handed neutrinos and the right-handed leptonic mixing matrix, which could in turn be used to predict the rates for neutrinoless double decay and lepton flavor violating violating processes. The LR scale at the LHC energies offers great hope of observing these low energy processes in the present and upcoming experiments.
SUM RULE FOR A SCHIFF-LIKE DIPOLE MOMENT
Authors: RADUTA A. A. , BUDACA R.
Published: April 2011

The energy-weighted sum rule for an electric dipole transition operator of a Schiff type differs from the Thomas–Reiche–Kuhn (TRK) sum rule by several corrective terms which depend on the number of system components, [Formula: see text]. For illustration the formalism was applied to the case of Na clusters. One concludes that the random phase approximation (RPA) results for Na clusters obey the modified TRK sum rule.
DIGITAL CRYPTOGRAPHY AND FEEDBACK SYNCHRONIZATION OF CHAOTIC SYSTEMS
Authors: MITRA MALA , BANERJEE SANTO
Published: April 2011

Secure communications via chaotic synchronization is demonstrated in this literature. At first we have designed a feedback controller for chaotic synchronization utilizing the Lyapunov stability theory for cascade-connected systems.The method has been applied successfully to make two identical systems globally asymptotically synchronized. The result of numerical simulations are given to validate the effectiveness of this method. Then we have discussed a new method of cryptography for this coupled system which is very simple to implement and effective.
PRESSURE-INDUCED METALLIZATION AND SUPERCONDUCTIVITY IN InP AND InN
Authors: IYAKUTTI K. , REJILA V. , RAJARAJESWARI M. , NIRMALA LOUIS C. , MAHALAKSHMI S.
Published: April 2011

The electronic band structure, structural phase transition, metallization and superconducting transition of cubic zinc blende-type indium phosphide ( InP ) and indium nitride ( InN ), under pressure, are studied using TB-LMTO method. These indium compounds become metals and superconductors under high pressure but before that they undergo structural phase transition from ZnS to NaCl structure. The ground-state properties and band gap values are compared with the experimental and previous theoretical results. From our analysis, it is found that the metallization pressure increases with increase of lattice constant. The superconducting transition temperatures (Tc) of InP and InN are obtained as a function of pressure for both the ZnS and NaCl structures and these compounds are identified as pressure-induced superconductors. When pressure is increased Tc increases in both the normal ( ZnS ) and high pressure ( NaCl ) structures. The dependence of Tc on electron–phonon mass enhancement factor λ shows that InP and InN are electron–phonon mediated superconductors. The non-occurrence of metallization, phase transition and onset of superconductivity simultaneously in InP and InN are confirmed.
STATISTIC CHARACTERISTICS OF QUANTUM GASES IN A CONFINED SPACE
Authors: LIN TONGLING , LIN BIHONG , SU GUOZHEN , CHEN JINCAN
Published: April 2011

With the help of the Euler–MacLaurin formula, the statistic characteristics of quantum gases confined in a rectangular box are investigated by using a unified way. Three components of the pressure tensor and the internal energy of the system are analytically derived. The important relation between the pressure tensor and the internal energy is strictly proved. It is pointed out that these results are different from those obtained in literature and textbooks under the thermodynamic limit condition. Moreover, the pressure of the system is rationally introduced with the help of the property of the diagonal tensor, so that some thermodynamic functions of the system may be conveniently obtained. The statistic characteristics of quantum and classical gases confined in some different containers are discussed, the influence of the size effect of the containers on the properties of gases is analyzed and some new significant results are obtained.
MOLECULAR DYNAMICS SIMULATION OF PULSED LASER ABLATION
Authors: GONG XIU-FANG , YANG GONG-XIAN , LI PENG , WANG YIN , NING XI-JING
Published: April 2011

We have developed a simplified molecular-dynamical model for simulating ablation of solid surfaces by laser pulses, and specifically investigated expansion of Cu cloud in vacuum vaporized on the surface, showing that the angular distributions of the plume depend on the shape of the laser spot on the surface. In particular, experimentally observed flipover effects have been obtained, and an adiabatic constant determined from our simulations via an adiabatic expansion model agrees well with previous measurements.
EFFECT OF SURFACE PASSIVATION ON CAPACITANCE–VOLTAGE CHARACTERISTICS OF Sn/p-Si SCHOTTKY CONTACTS
Authors: TEMİRCİ CABİR , BATI BAHRI
Published: April 2011

We have fabricated the Sn/p-Si Schottky barrier diodes with the interfacial layer metal–insulator–semiconductor (D-MIS) and the surface passivation metal–semiconductor MS (D-MS) by the anodization or chemical treatment method. The current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the devices were measured at room temperature. We obtained that the excess capacitance (C0) value of the MIS Sn/p-Si diode with the anodic oxide layer of 16.88 pF and 0.12 pF for the MS Sn/p-Si ideal diode with the surface passivation by the anodization or chemical treatment method from reverse bias C–V characteristics. Thus, we have succeeded to diminish the excess capacitance value to the limit of 0.12 pF for the MS Sn/p-Si diode by using the anodization or chemical treatment method.
SCALABLE ARCHITECTURE FOR HIGH-SPEED MULTIDIMENSIONAL FUZZY INFERENCE SYSTEMS
Authors: DEL CAMPO INÉS , ECHANOBE JAVIER , BASTERRETXEA KOLDO , BOSQUE GUILLERMO
Published: April 2011

This paper presents a scalable architecture suitable for the implementation of high-speed fuzzy inference systems on reconfigurable hardware. The main features of the proposed architecture, based on the Takagi–Sugeno inference model, are scalability, high performance, and flexibility. A scalable fuzzy inference system (FIS) must be efficient and practical when applied to complex situations, such as multidimensional problems with a large number of membership functions and a large rule base. Several current application areas of fuzzy computation require such enhanced capabilities to deal with real-time problems (e.g., robotics, automotive control, etc.). Scalability and high performance of the proposed solution have been achieved by exploiting the inherent parallelism of the inference model, while flexibility has been obtained by applying hardware/software codesign techniques to reconfigurable hardware. Last generation reconfigurable technologies, particularly field programmable gate arrays (FPGAs), make it possible to implement the whole embedded FIS (e.g., processor core, memory blocks, peripherals, and specific hardware for fuzzy inference) on a single chip with the consequent savings in size, cost, and power consumption. As a prototyping example, we implemented a complex fuzzy controller for a vehicle semi-active suspension system composed of four three-input FIS on a single FPGA of the Xilinx's Virtex 5 device family.
A FUZZY-UPDATED CACHE OF AUTOMATA MATCHING FOR EMBEDDED NETWORK PROCESSOR
Authors: TSENG KUO-KUN , LAI YEONG-LIN , CHEN CHIN-CHENG , HSU CHIH-YU
Published: April 2011

Light-weight network gateways often employ a cost-effective embedded network processor and have received a strong demand for empowering content filtering services. In this regard, we were motivated to propose a specialized cache, fuzzy-updated cache automata matching (FCAM) circuit for accelerating the embedded network processors. Although automata matching algorithms are robust with deterministic matching time, there is still plenty of room for improving its average-case performance. The proposed FCAM employs cache to accelerate the root state and nonroot state with the multiple characters matching, and applies the fuzzy decision to improve the cache performance. In our experiment, the FPGA implementation of FCAM can perform at the rate of 10.5 Giga bits per second with the patterns of 25,642 bytes. This performance is superior to previous matching hardware in terms of throughput and pattern set.
HARDWARE IMPLEMENTATIONS OF MLP ARTIFICIAL NEURAL NETWORKS WITH CONFIGURABLE TOPOLOGY
Authors: DA SILVA RODRIGO MARTINS , NEDJAH NADIA , MOURELLE LUIZA DE MACEDO
Published: April 2011

In this paper, we devise an adaptive hardware architecture for ANNs that takes advantage of the dedicated adder blocks, commonly called MACs, to compute both the weighted sum and activation function. The proposed architecture requires a reduced silicon area considering the fact that the MACs come for free as these are FPGA's built-in hardcores and if not used, they cannot be optimized in the final design. The implementation uses integer fixed point arithmetic and operates with fractions to represent real numbers. The hardware is fast because it is massively parallel, yet it is compact as it has a single physical layer of neurons while the remaining are virtual. Besides, the proposed architecture is adaptive; so it is designed to adjust itself on-the-fly to the user-defined configuration of the neural network, i.e., the number of layers and neurons per layer as well as the topology of the ANN can be configured with no extra hardware changes nor any supplementary design effort.
ROBUST CONTROL FOR UNCERTAIN DELAY SYSTEM
Authors: FARKH RIHEM , LAABIDII KAOUTHER , KSOURI MEKKI
Published: April 2011

In this paper, the Generalized Kharitonov Theorem for quasi-polynomials is exploited for the purpose of synthesizing a robust controller. The aim here is to develop a controller to simultaneously stabilize a given interval plant family with unknowing and bounded time delay. Using a constructive procedure based on Hermite–Biehler theorem, we obtain all PI gains that stabilize an uncertain first-order delay system. An application example is presented for the temperature control of a heated air stream, process trainer PT326.
DESIGN AND MEASUREMENTS OF A MULTIPLE-OUTPUT TRANSMITTER FOR MIMO APPLICATIONS
Authors: VOTIS CONSTANTINOS I. , KOSTARAKIS PANOS , IVRISSIMTZIS LEONIDAS P.
Published: April 2011

The design of a multiple-output transmitter for digital beamforming (DBF), Multiple-Input Multiple-Output (MIMO) and channel sounder applications, based on Direct Digital Synthesis (DDS) system is presented and investigated in terms of antenna array performance. DDS generates independently modulated signals on specific carrier frequencies and is employed as the first stage in the proposed implementation, furnishing output signal of configurable amplitude, phase and frequency. The resulting phase progression, amplitude and beamforming accuracy of a beam steering array are further investigated, showing that the proposed architecture can provide a steering beam with high accuracy. Experimental results of system performance indicate that this architecture can drive efficiently and accurately an antenna array with independent modulated RF signals, with programmable frequency, initial phase, and magnitude.
HIGH PERFORMANCE MONTGOMERY MODULAR MULTIPLIER WITH A NEW RECODING METHOD
Authors: MANOCHEHRI KOOROUSH , SADEGHIYAN BABAK , POURMOZAFARI SAADAT
Published: April 2011

Modular calculations are widely used in many applications, especially in public key cryptography. Such operations are very time consuming, due to their long operands. To improve the performance of these calculations, many methods have been introduced. Montgomery modular multiplication is an example of such a solution to enhance the performance of modular multiplication and modular exponentiation. The radix-2 version of this method is simple and fast for hardware implementation, where multi-operand adders are required for its implementation. So far, Carry-Save-Adder (CSA) gives the best performance for multi-addition. In this paper, we propose a new recoding method for the Montgomery modular multiplier to enhance its performance. This is done through replacing CSA blocks with new blocks that have better performances than CSA in multi-addition calculations. With this replacement, we can theoretically have up to 40% reduction in area gates. In our experiments, we obtained 5.8% area reduction and 3% speed improvement in a hardware implementation. The idea behind our proposed method is the use of bitwise subtraction operator, where no carry propagation is needed. This recoding method of operands can also be used in many aspects of computer arithmetic, algorithms and computational hardware, such as multiplication, exponentiation and etc., in order to enhance their performances.
ON THE 1D AND 2D ROGERS–RAMANUJAN CONTINUED FRACTIONS
Authors: ANTONIOU GEORGE E. , KATSALIS PANAGIOTA A.
Published: April 2011

In this paper the classical and generalized numerical Rogers–Ramanujan continued fractions are extended to a polynomial continued fraction in one and two dimensions. Using the new continued fractions, the fundamental recurrence formulas and a fast algorithm, based on matrix formulations, are given for the computation of their transfer functions. The presented matrix formulations can provide a new perspective to the analysis and design of Ladder-continued fraction filters in one and two dimensions signal processing. The simplicity and efficiency of the presented algorithms are illustrated by step-by-step examples.
DESIGN AND IMPLEMENTATION OF SYMBOL DETECTOR FOR MIMO SPATIAL MULTIPLEXING SYSTEMS
Authors: JUNG YUNHO , LEE SEONGJOO , KIM JAESEOK
Published: April 2011

In this paper, we propose an efficient symbol detection algorithm for multiple-input multiple-output spatial multiplexing (MIMO-SM) systems and present its design and implementation results. By enhancing the error performance of the first detected symbol that causes error propagation, the proposed algorithm achieves a considerable performance gain compared with the conventional sorted QR decomposition (SQRD) based detection and the ordered successive detection (OSD) algorithms. The bit error rate (BER) performance of the proposed detection algorithm is evaluated by a simulation. In the case of a 16QAM MIMO-SM system with 4 transmit and 4 receive (4 × 4) antennas, at BER = 10-3 the proposed algorithm results in a gain improvement of about 2.5–13.5 dB over the previous algorithms. The proposed detection algorithm was designed in a hardware description language (HDL) and synthesized to gate-level circuits using 0.18 μm 1.8 V CMOS standard cell library. The results show that the proposed algorithm can be implemented without increasing the hardware costs significantly.
DESIGN OF AN INTEGRATED SCANNING MICROMIRROR DRIVER IN BCD TECHNOLOGY
Authors: SAPONARA SERGIO , BALDETTI TOMMASO , FANUCCI LUCA , VOLPI EMILIO , D'ASCOLI FRANCESCO
Published: April 2011

The paper presents the design and characterization of a smart IC driver for MEMS scanning micromirrors. The driver integrates in 0.18 μm BCD technology the cascade of the following circuits: resistor-string DAC circuitry for direct interface to a host digital processing unit, a voltage buffer between the DAC and the High-Voltage (HV) stage, and a fully-differential HV amplifier with programmable output common mode. A couple of the designed DACs permits to generate, starting from digital samples, low-voltage analog stimuli. This signal amplified up to 25 V by the HV stage provides the electrostatical actuation of the micromirror. When compared to state-of-the-art the driver offers an integrated solution with good dynamic performances.
EXPLOITING INSTRUCTION REUSE TO IMPROVE THE PERFORMANCE OF DUAL INSTRUCTION EXECUTION
Authors: PILLAI ABHISHEK , ZHANG WEI
Published: April 2011

Dual instruction execution (DIE) is an effective instruction-level temporal redundancy technique to improve the datapath reliability against transient errors for superscalar microprocessors. However, previous study shows that the performance overhead of dual instruction execution on an out-of-order core is substantial, primarily due to the serious resource contention problems such as the ALU bandwidth. In this paper, we propose a novel approach to reducing the performance overhead of DIE without compromising the datapath reliability. In the proposed scheme, both the primary and the duplicate instructions of DIE can exploit the ECC-protected instruction reuse buffer (IRB) for mitigating the resource contention of DIE by minimizing the number of dynamic instructions executed, leading to better performance without impacting the reliability of DIE. Our experiments indicate that the proposed approach can reduce the performance loss of dual instruction execution by up to 70.8%, with 51.1% on average, and can reduce the performance loss of DIE–IRB by up to 17.2%, with 7.1% on average, while providing reliability comparable to DIE or DIE–IRB.
OBSERVATION OF CHAOTIC BEATS IN A DRIVEN MEMRISTIVE CHUA'S CIRCUIT
Authors: ISHAQ AHAMED A. , SRINIVASAN K. , MURALI K. , LAKSHMANAN M.
Published: April 2011

In this paper, a time varying resistive circuit realizing the action of an active three segment piecewise linear flux controlled memristor is proposed. Using this as the nonlinearity, a driven Chua's circuit is implemented. The phenomenon of chaotic beats in this circuit is observed for a suitable choice of parameters. The memristor acts as a chaotically time varying resistor (CTVR), switching between a less conductive OFF state and a more conductive ON state. This chaotic switching is governed by the dynamics of the driven Chua's circuit of which the memristor is an integral part. The occurrence of beats is essentially due to the interaction of the memristor aided self-oscillations of the circuit and the external driving sinusoidal forcing. Upon slight tuning/detuning of the frequencies of the memristor switching and that of the external force, constructive and destructive interferences occur leading to revivals and collapses in amplitudes of the circuit variables, which we refer as chaotic beats. Numerical simulations and Multisim modeling as well as statistical analyses have been carried out to observe as well as to understand and verify the mechanism leading to chaotic beats.
GEOMETRY OF DYNAMICAL SYSTEMS AND TOPOLOGICAL STABILITY: FROM BIFURCATION, CHAOS AND FRACTALS TO DYNAMICS IN NATURAL AND LIFE SCIENCES
Authors: BOI LUCIANO
Published: April 2011

The aim of this article is to review some basic concepts of the geometric theory of dynamical systems and stability. In this context, we also consider the related fundamental notions of broken symmetry, bifurcation and chaos. That of bifurcation is a very sophisticated mathematical concept, which displays a number of local and global behaviors of those spaces within which a large variety of natural forms unfold. The suited theoretical framework for understanding deeply the concept of bifurcation is the study of singularities of mappings, their topological structures and their classification into equivalence classes. Furthermore, we consider the fundamental role played by the phenomena of breaking symmetry and chaos in the evolution and organization of various natural and living systems. In the last part of the paper, we present some striking features and results of nonlinearity and stability in the framework of the geometrical theory of dynamical systems.
FPT-ALGORITHMS FOR MINIMUM-BENDS TOURS
Authors: ESTIVILL-CASTRO VLADIMIR , HEEDNACRAM APICHAT , SURAWEERA FRANCIS
Published: April 2011

This paper discusses the κ-BENDS TRAVELING SALESMAN PROBLEM. In this NP-complete problem, the inputs are n points in the plane and a positive integer κ, and we are asked whether we can travel in straight lines through these n points with at most κ bends. There are a number of applications where minimizing the number of bends in the tour is desirable because bends are considered very costly. We prove that this problem is fixed-parameter tractable (FPT). The proof is based on the kernelization approach. We also consider the RECTILINEAR κ-BENDS TRAVELING SALESMAN PROBLEM, which requires that the line-segments be axis-parallel. 1 Note that a rectilinear tour with κ bends is a cover with κ-line segments, and therefore a cover by lines. We introduce two types of constraints derived from the distinction between line-segments and lines. We derive FPT-algorithms with different techniques and improved time complexity for these cases.
PERIODIC OSCILLATIONS IN A SPATIALLY EXPLICIT MODEL WITH DELAY EFFECT FOR VEGETATION DYNAMICS IN FRESHWATER MARSHES
Authors: WANG KAIFA , ZHANG NA , NIU DECAO
Published: April 2011

Time delay is incorporated into a spatially explicit model for vegetation dynamics in freshwater marshes and the effect of the delay is investigated by using qualitative analysis and numerical simulation. If the specific rate of plant senescence is sufficient small then spatial homogeneity will be induced eventually for any delay, while if it is large, then a switches may occurs as time delay increases and there is a periodic oscillations if it exceed a critical value. Thus, delay time in ecosystem may be one of the important factors to induce temporal fluctuation in nature.
ALGORITHM-HARDWARE CODESIGN OF A FAST PARALLEL ROUTING ARCHITECTURE FOR CLOS NETWORKS
Authors: ZHENG S. Q. , GUMASTE A. , LU E.
Published: April 2011

Clos networks are an important class of switching networks due to their modular structure and much lower cost compared with crossbars. For routing I/O permutations of Clos networks, sequential routing algorithms are too slow, and all known parallel algorithms are not practical. We present the algorithm-hardware codesign of a unified fast parallel routing architecture called distributed pipeline routing (DPR) architecture for rearrangeable nonblocking and strictly nonblocking Clos networks. The DPR architecture uses a linear interconnection structure and processing elements that performs only shift and logic AND operations. We show that a DPR architecture can route any permutation in rearrangeable nonblocking and strictly nonblocking Clos networks in [Formula: see text] time. The same architecture can be used to carry out control of any group of connection/disconnection requests for strictly nonblocking Clos networks in [Formula: see text] time. Several speeding-up techniques are also presented. This architecture is designed for Clos-based packet and circuit switches of practical sizes.
DISCRETE ELEMENT METHOD FOR MULTISCALE MODELING
Authors: BRUCHMÜLLER J. , GU S. , LUO K. H. , VAN WACHEM B. G. M.
Published: April 2011

A discrete element method (DEM) has been developed to provide highly accurate and detailed predictions of the Lagrangian particle phase. Especially in this study, DEM has been used together with an Eulerian approach for the fluid phase to look at interphase exchange phenomena in a multiphase-multiscale modeling approach. The drying process inside a fluidized bed coffee bean roaster has been chosen. Herein, heat, mass, and momentum transport are solved on a fluid cell level; heat, mass, and momentum transfer coefficients are solved at a particle scale level; and 1D temperature and moisture content profiles are solved inside each coffee bean on a sub-particle scale level. Therefore, this multiscale approach provides much more information compared to existing coffee bean roaster models. In this work, a detailed description of this method is provided and results on different scale levels have been discussed. Modeling data and experimental results are compared and found to be in good agreement.
A MULTIPHASE ANALYSIS FOR ENVIRONMENTAL IMPACT ASSESSMENT WITH θ-STOCK FINITE ELEMENT PROGRAM
Authors: GATMIRI B. , HEMMATI S. , ARSON C. , AMIRZEHNI E.
Published: April 2011

In the THM modeling of multiphase medium, the coupling effects of skeleton, suction, and temperature have been integrated via the concept of state surfaces of void ratio and degree of saturation. Based on proposed formulation, a fully coupled numerical model for the behavior of soil deformation, water flow, air flow, heat flow in unsaturated soil has been developed and integrated in a finite element code θ-Stock by the first author. This program is conceived with this idea that it will be able to analyze the response of a soil in different states of humidity to mechanical, thermal loading, and also damage phenomena. Damage model is dedicated to unsaturated brittle rocks. It mixes phenomenological and micromechanical concepts and is formulated based on the use of independent state variables. The expression of the liquid permeability is modified in order to represent the influence of fracturing on interstitial fluid flows. The final matrix form of established field equations of the proposed model for unsaturated case has been encoded for this particular purpose, in a finite element program which had been developed for dry and saturated soils previously.
MULTISCALE MODELING OF FLUID AND SOLUTE TRANSPORT IN SOFT TISSUES AND MICROVESSELS
Authors: LU YILING , WANG WEN
Published: April 2011

This study focuses on the movement of particles and extracellular fluid in soft tissues and microvessels. It analyzes modeling applications in biological and physiological fluids at a range of different length scales: from between a few tens to several hundred nanometers, on the endothelial glycocalyx and its effects on interactions between blood and the vessel wall; to a few micrometers, on movement of blood cells in capillaries and transcapillary exchange; to a few millimetres and centimetres, on extracellular matrix deformation and interstitial fluid movement in soft tissues. Interactions between blood cells and capillary wall are discussed when the sizes of the two are of the same order of magnitude, with the glycocalyx on the endothelial and red cell membranes being considered. Exchange of fluid, solutes, and gases by microvessels are highlighted when capillaries have counter-current arrangements. This anatomical feature exists in a number of tissues and is the key in the renal medulla on the urinary concentrating mechanism. The paper also addresses an important phenomenon on the transport of macromolecules. Concentration polarization of hyaluronan on the synovial lining of joint cavities is presented to demonstrate how the mechanism works in principle and how model predictions agree to experimental observations quantitatively.
FINITE ELEMENT MODELING OF TRANSVERSE DEFORMATION IN REPRESENTATIVE VOLUME ELEMENTS OF CERAMIC MATRIX COMPOSITES (CMCs)
Authors: TANG C. , SHEIKH M. A. , HAYHURST D. R.
Published: April 2011

The paper reports the use of the finite element method to model longitudinal and transverse deformation of representative volume elements (RVE) of ceramic matrix composites subjected to uniaxial loading parallel to fibers. Cohesive elements have been used to model two forms of damage: fracture initiation and propagation both within the matrix, and along the fiber–matrix interface. From the knowledge of the constituent materials behavior, the FE technique has been used to predict the stress–strain behavior and the variation of Poisson's ratio of the RVE due to these two damage forms; but the model does not cater for fiber failure. The RVE predictions have been benchmarked against experimental results for Nicalon-CAS material and good agreement has been obtained. Comparison of the predicted behavior of the single Nicalon-CAS RVE with experimental data for unidirectional tows indicates that the stress–strain curve is predominantly controlled by the Weibull distribution of fiber failure stress, while the degradation of Poisson's ratio is determined by the Weibull distribution of interfacial strength. The same approach has been used for a HITCO C/C material for which transverse deformation behavior is unknown. The results for the HITCO C/C material, as for the Nicalon-CAS, show that the fiber behavior determines the ultimate failure of the RVE, and that interface debonding is the controlling mechanism for the variation of the Poisson ratio with axial strain.
CONVERGING MINICHANNEL EFFECTS IN THE CONDENSER OF A SMALL CPL HEAT PIPE
Authors: KARNG SARNG WOO , KIM JIN-HO S. , LEE SEUNG-CHUL
Published: April 2011

Microchannels or minichannels are widely used for cooling high density power electronic devices, such as heat pipes and heat exchangers. The interfacial behaviors between liquid and gas phases are very important to understand the flow characteristics in microchannels or minichannels. One of the problems at the capillary pumped loop (CPL) heat pipes is the backflow of vapor through the liquid line toward the evaporator. Therefore, we applied the converging minichannels at the condenser to avoid the backflow. In this paper, a numerical analysis on the interfacial velocities and the total pressures depending on variations of the converging rate and the depth of the minichannels was performed. It was shown that the converging minichannels can reduce the backflow effect. The proper dimension of the minichannels to reduce the vapor backflow was also found.
ANALYTICAL STUDY ON THE HEATING PERFORMANCE OF A MULTI-TYPE HEAT PUMP SYSTEM WITH n-INDOOR UNITS
Authors: CHOI JONG WON , LEE IL HWAN , KIM MIN SOO
Published: April 2011

This paper presents the steady-state heating performance of a multi-type heat pump system. The compressor and expansion valves are described by a lumped parameter model for its rapid and prompt response to the disturbances compared to those of the heat exchangers. Fully distributed model (or spatially dependent model) is used for the evaporator and condenser since the lumped method does not guarantee enough accuracy in estimating the performance of heat exchangers with phase change. Most researches on the numerical simulation in heat pump system focuses on the precise modeling for the steady or transient states while few researches on the simulations consider the relationships among several indoor units, expansion valve openings and compressor speed in multi-type heat pump system. In this study, the heating performance of a multi-type heat pump system using R410A with three indoor units is simulated for the investigation of system characteristics and the simulation results are verified for several experimental conditions. Finally, the simulation technique is extended to the system with n-indoor units.
REFRIGERANTS OF THE METHANE, ETHANE AND PROPANE SERIES: THERMAL CONDUCTIVITY CALCULATION ALONG THE SATURATION LINE
Authors: LATINI GIOVANNI , SOTTE MARCO
Published: April 2011

In this paper, a formula is presented for the calculation of thermal conductivity of liquids along the saturation line. The formula is valid for organic compounds in a wide reduced temperature range (0.30 to 0.95), but is proven to be particularly reliable for refrigerants by testing it on a database of more than 40 refrigerants of the methane, ethane and propane series that includes almost all those reported by ASHRAE in its 2007 revision of standard 34. The test on the indicated refrigerants shows a very satisfying performance: mean and maximum absolute deviations between calculated values and experimental data are generally less than 3% and 8% respectively. The proposed formula is very simple; three characteristic parameters express the thermal conductivity dependence on the reduced temperature: the constant Φ, a multiplying factor A, and an exponent a.
PREDICTION OF THERMAL CONDUCTIVITY OF R32, R125, R134a, R143a AND R152a AT ZERO DENSITY VIA SEMI-EMPIRICALLY-BASED ASSESSMENT
Authors: HAGHIGHI BEHZAD , HEIDARI FATEMEH , HAGHIGHI BEHNOUD , PAPARI MOHAMMAD MEHDI , HAGHIGHI BEHRAD
Published: April 2011

The robust and efficient procedure is presented to calculate the transport properties, especially thermal conductivity coefficients, for gaseous state of difluoromethane (R32), pentafluoroethane (R125), 1, 1, 1, 2 tetrafluoroethane (R134a), 1, 1, 1 trifluoroethane (R143a) and 1, 1 difluoroethane (R152a) at zero density. The McLinden et al.'s1approach of the extended corresponding states has been used for calculating the contribution of molecular degree of freedom to the thermal conductivity of these refrigerants. The Lennard–Jones 12-6 (LJ 12-6) potential energy function is used as the initial model potential required by the technique. The interaction potential energies from the inversion procedure reproduce the thermal conductivity coefficients commensurate to the best measurements.
The Origin of Behavior
Authors: Brennan Thomas J. , Lo Andrew W.
Published: April 2011

We propose a single evolutionary explanation for the origin of several behaviors that have been observed in organisms ranging from ants to human subjects, including risk-sensitive foraging, risk aversion, loss aversion, probability matching, randomization, and diversification. Given an initial population of individuals, each assigned a purely arbitrary behavior with respect to a binary choice problem, and assuming that offspring behave identically to their parents, only those behaviors linked to reproductive success will survive, and less reproductively successful behaviors will disappear at exponential rates. When the uncertainty in reproductive success is systematic, natural selection yields behaviors that may be individually sub-optimal but are optimal from the population perspective; when reproductive uncertainty is idiosyncratic, the individual and population perspectives coincide. This framework generates a surprisingly rich set of behaviors, and the simplicity and generality of our model suggest that these derived behaviors are primitive and nearly universal within and across species.
Metaphors, Models & Theories
Authors: Derman Emanuel
Published: April 2011

Theories deal with the world on its own terms, absolutely. Models are metaphors, relative descriptions of the object of their attention that compare it to something similar already better understood via theories. Models are reductions in dimensionality that always simplify and sweep dirt under the rug. Theories tell you what something is. Models tell you merely what something is partially like.
BP's Failure to Debias: Underscoring the Importance of Behavioral Corporate Finance
Authors: Shefrin Hersh , Cervellati Enrico Maria
Published: April 2011

This paper provides a behavioral analysis of BP, whose capital budgeting decisions in the last decade have resulted in a series of high-profile accidents, including the worst environmental disaster in US history. This analysis uses BP as a vehicle to discuss the application of business processes and psychological pitfalls to analyze corporate culture. The paper identifies weaknesses and vulnerabilities in BP's culture, makes comparisons with the corporate financial practices at other firms, and offers suggestions about how BP can engage in debiasing. Notably, the paper also suggests that insufficient knowledge of behavioral decision making resulted in analysts, investors, and regulators attaching insufficient emphasis to the risks in BP's operations. The paper calls for more attention to the psychological aspects of corporate behavior by analysts, regulators, corporate managers, and academics.
Superconformal Ni Electrodeposition Using 2-Mercaptobenzimidazole
Authors: Lee Chang Hwa , Bonevich John E. , Bertocci Ugo , Steffens Kristen L. , Moffat Thomas P.
Published: April 2011

Ni superconformal filling of sub-micrometer trenches is demonstrated using a Watts bath containing an inhibitor 2-mercaptobenzimidazole (MBI). Hysteretic voltammetry marks the breakdown of the MBI-induced passive-state coincident with the onset of Ni deposition. Chronoamperometry reveals that disruption of MBI inhibition is a strong function of the immersion conditions and potential conditioning. The passive to active transition involves a competition between potential-dependent MBI adsorption and its subsequent deactivation and/or consumption during Ni deposition. Breakdown of the MBI-passivating layer results in sulfide formation and its incorporation into the Ni film. The current efficiency of Ni deposition on the activated surface is close to that for the additive-free electrolyte. For recessed surface features, such as trenches, inhibition-breakdown initiates preferentially at the bottom corners. Scanning and transmission electron microscopy (SEM/TEM) studies show the growth front within the trenches initially develops as a v-notch shape while negligible deposition occurs on the free surface. This is followed by the onset of Ni deposition over the entire surface profile that results in trench filling by geometrical leveling. Depending on the specimen immersion process a distinct microstructural transition marks the change in growth mode from a superconformal deposition mode to geometrical leveling during trench filling.
Reduction of Hot Carrier Effects in Silicon-on-Glass TFTs
Authors: Mativenga M. , Choi M. H. , Choi W. , Choi J. W. , Jang J. , Mruthyunjaya R. , Tredwell T. J. , Mozdy E. , Kosik-Williams C.
Published: April 2011

Hot carrier (HC) instability of thin-film transistors (TFTs) fabricated on single-crystal,silicon-on-glass (SiOG) substrates is studied. The formation of the SiOG substrate is achieved by the transfer of a single-crystal silicon film to a display-glass substrate. The transfer process creates an in-situ barrier layer free of mobile ions in the glass adjacent the silicon film. The n- and p-channel TFT transfer characteristics typically exhibit excellent on-state performance with gate voltage swing values of 180 mV/decade, electron and hole mobilities of ∼ 251 and 201 cm2/V·s respectively, and threshold voltages of approximately −0.3 and −1.2 V for the n- and p-channel TFT’s respectively. While p-channel TFTs exhibit good stability, on-current degradation is observed in the transfer characteristics of the n-channel TFT. The degradation is due to HC stress. In this study, the integration of a lightly doped drain (LDD) structure in the n-channel SiOG TFTs to minimize HC instability is reported. The LDD design incorporates 2 μm offset regions. The offset regions are lightly doped (n-) with phosphorus ions implanted at 10 keV. N-levels of ∼ 1 × 1013, 2 × 1013, and 3 × 1013 cm−2 are analyzed to determine the optimum doping conditions that reduce HC instability while minimizing degradation in the on-state device performance.
The Synthesis and Luminescence Properties of a Red Phosphor Material (Ca1−xEux)3Al2O6
Authors: Zhou T. L. , Wang H. R. , Liu F. S. , Zhang H. , Liu Q. L.
Published: April 2011

(Ca1−xEux)3Al2O6, a red light-emitting phosphor with the excitation of purple-blue light, was prepared by traditional solid reaction method with reducing atmosphere at 1350°C for 4 h in a tube furnace. CaEuAlO4 emerged as an impurity phase when the content of Eu, x, in (Ca1−xEux)3Al2O6 exceeds 0.03. Furthermore, the content of CaEuAlO4 rises with Eu concentration. A strong excitation band centering at 467 nm and a broad emission band centering at 650 nm have been discovered in this phosphor, making it possible to manufacture a bargain price white light LEDs with high CRI.
Extensive effects of in vitro oocyte maturation on rhesus monkey cumulus cell transcriptome
Authors: Lee Young S. , VandeVoort Catherine A. , Gaughan John P. , Midic Uros , Obradovic Zoran , Latham Keith E.
Published: April 2011

The elaboration of a quality oocyte is integrally linked to the correct developmental progression of cumulus cell phenotype. In humans and nonhuman primates, oocyte quality is diminished with in vitro maturation. To determine the changes in gene expression in rhesus monkey cumulus cells (CC) that occur during the final day prior to oocyte maturation and how these changes differ between in vitro (IVM) and in vivo maturation (VVM), we completed a detailed comparison of transcriptomes using the Affymetrix gene array. We observed a large number of genes differing in expression when comparing IVM-CC and VVM-CC directly but a much larger number of differences when comparing the transitions from the prematuration to the post-IVM and post-VVM states. We observed a truncation or delay in the normal pattern of gene regulation but also remarkable compensatory changes in gene expression during IVM. Among the genes affected by IVM are those that contribute to productive cell-cell interactions between cumulus cell and oocyte and between cumulus cells. Numerous genes involved in lipid metabolism are incorrectly regulated during IVM, and the synthesis of sex hormones appears not to be suppressed during IVM. We identified a panel of 24 marker genes, the expression of which should provide the foundation for understanding how IVM can be improved for monitoring IVM conditions and for diagnosing oocyte quality.
Measurement of the extraocular spike potential during saccade countermanding
Authors: Godlove David C. , Garr Anna K. , Woodman Geoffrey F. , Schall Jeffrey D.
Published: April 2011

The stop signal task is used to investigate motor inhibition. Several groups have reported partial electromyogram (EMG) activation when subjects successfully withhold manual responses and have used this finding to define the nature of response inhibition properties in the spinal motor system. It is unknown whether subthreshold EMG activation from extraocular muscles can be detected in the saccadic response version of the stop signal task. The saccadic spike potential provides a way to examine extraocular EMG activation associated with eye movements in electroencephalogram (EEG) recordings. We used several techniques to isolate extraocular EMG activation from anterior electrode locations of EEG recorded from macaque monkeys. Robust EMG activation was present when eye movements were made, but no activation was detected when saccades were deemed canceled. This work highlights a key difference between the spinal motor system and the saccade system.
Remodeling the cardiac transcriptional landscape with diet
Authors: Luczak Elizabeth D. , Barthel Kristen K. B. , Stauffer Brian L. , Konhilas John P. , Cheung Tom H. , Leinwand Leslie A.
Published: April 2011

The perception that soy food products and dietary supplements will have beneficial effects on cardiovascular health has led to a massive consumer market. However, we have previously noted that diet profoundly affects disease progression in a genetic model of hypertrophic cardiomyopathy (HCM). In this model, a soy-based diet negatively impacts cardiac function in male mice. Given the frequent connection between functional changes and transcriptional changes, we investigated the effect of diet (soy- vs. milk-based) on cardiac gene expression and how it is affected by the additional factors of sex and disease. We found that gene expression in the heart is altered more by diet than by sex or an inherited disease. We also found that the healthy male heart may be sensitized to dietary perturbations of gene expression in that it displays a gene expression profile more similar to diseased male and female hearts than to healthy female hearts. These observations may in part account for documented divergence in HCM phenotypes between males and females and between diets.
Detrusor Arreflexia as an End Stage of Neurogenic Bladder in HAM/TSP?
Authors: Tannus Matheus , Tanajura Davi , Sundberg Michael A. , Oliveira Paulo , Castro Neviton , Santos André Muniz
Published: April 2011

The HTLV-1 virus is a known agent involved in the development of HAM/TSP. Past studies have typically observed patients with autonomic dysfunction consisting of detrusor overactivity and detrusor-sphincter dyssynergia, with the occasional observation of underactive detrusor or detrusor arreflexia. However, studies have not yet evaluated the progression of neurogenic bladder over time. In this paper, we describe a HAM/TSP patient with the initial development of overactive detrusor, and subsequent development of detrusor arreflexia. Given a paucity of studies characterizing the effects of HTLV-1 on the autonomic nervous system, particularly aspects controlling continence, this patient's clinical course may represent one type of end point for patients with HAM/TSP and neurogenic bladder. Further cohort or case-series studies, with particular emphasis on the progression of neurogenic bladder, are needed to evaluate the significance of this described case in relation to typical disease progression patterns.