bluuebunny/crossref_metadata_2025 huggingface dataset:
Cost‐effectiveness analysis of voglibose for prevention of type 2 diabetes mellitus in Japanese patients with impaired glucose tolerance
Authors: Ikeda Shunya , Kobayashi Makoto , Tajima Naoko
Published: August 2010

Aims/Introduction:  The objective of this study was to estimate the cost‐effectiveness of administering voglibose, in addition to standard care of diet and exercise, compared with standard care alone for high‐risk Japanese patients with impaired glucose tolerance.

Materials and Methods:  A Markov model was constructed to estimate the long‐term prognosis of individuals with impaired glucose tolerance, in terms of expected medical costs and life expectancy. Transition probabilities were derived from the results of a clinical trial of voglibose, as well as the epidemiological information. Effectiveness was evaluated by life expectancy and only direct costs were considered. The future costs and effectiveness were discounted by 3% per year.

Results:  Estimated expected lifetime costs for the voglibose administration group and the standard care group was JPY718,724 ($US7598) and JPY1,365,405 ($US14,433), respectively, with voglibose administration resulting in saving of JPY646,681 ($US6836). Estimated life expectancy was 18.672 and 18.073 years, respectively, with life expectancy prolonged by 0.599 years when voglibose was administered together with the standard care.

Conclusions:  In order to prevent type 2 diabetes among Japanese patients with impaired glucose tolerance, voglibose with standard care resulted in cost‐saving, as well as prolongation of life expectancy, compared with standard care alone. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.0052.x, 2010)
Community‐specific, preventive oral health policies: preventive measures on dental caries
Authors: Esfandiari Shahrokh , Jamal Nekky , Feine Jocelyne
Published: August 2010

In all health fields, limited infrastructure and resources hinder the provision of basic services to low‐income populations. Subsequently, oral health is often neglected, as over 90% of caries remains untreated in developing communities. In order to deliver the most cost‐effective prevention methods, public health officials must assess each available strategy on an individual community basis. In this paper, examples from oral health will demonstrate the importance of community‐specific determinants in the formation of preventive public health policies. These determinants include economical, cultural, social, and political elements that can assist policy makers in generating effective functional public health policies.
Nd:YAG (1064 nm) laser for the treatment of chronic periodontitis: a pilot study
Authors: Jensen Jørgen , Lulic Martina , Heitz‐Mayfield Lisa J.A. , Joss Andreas , Lang Niklaus P.
Published: August 2010

Aim:  To evaluate the clinical and microbiological effects of neodymium: yttrium–aluminum–garnet laser therapy as an adjunct to scaling and root planing during the hygienic phase.

Methods:  In eight patients, sites with a mean probing pocket depth (PPD) of ≥5 mm were treated by either scaling and root planing (n = 28) (control) or by scaling and root planing and adjunctive laser therapy (n = 28) (power: 5 W). Re‐evaluation was at 4–6 weeks. Thereafter, remaining pockets (mean PPD ≥5 mm) were eliminated by either laser surgery (power: 7 W) or gingivectomy (control).

Results:  At baseline, the mean PPD of sites originally presenting with a mean PPD ≥4 mm were 4.69 and 4.73 mm in the test and control sites, respectively. Six months following surgery, there was a similar average mean PPD reduction in the test (1.18 mm, P < 0.01) and control sites (1.35 mm, P < 0.01). Also, the reduction in bleeding on probing in both groups was statistically significant (P < 0.01, paired t‐tests). No statistically‐significant differences between the test and control sites were found for any clinical or microbiological parameters at baseline, after initial, and 3 or 6 months’ post‐surgical therapy.

Conclusion:  During the hygienic phase, neodymium: yttrium–aluminum–garnet (1064 nm) laser treatment yielded no superiority in clinical efficacy compared to conventional debridement. Laser gingivectomy resulted in similar treatment outcomes (mean PPD and bleeding on probing reduction), as did conventional gingivectomy.
Welfare and health of horses transported for slaughter within the European Union Part 1: Methodology and descriptive data
Authors: MARLIN D. , KETTLEWELL P. , PARKIN T. , KENNEDY M. , BROOM D. , WOOD J.
Published: August 2010

Reasons for performing study:Anecdotal evidence collected by a variety of organisations has highlighted poor welfare in horses transported long distances to slaughter within the European Union.

Objective:To investigate welfare of horses being transported long distances within the EU to slaughter.

Methods:Data on transported horses were recorded at 2 assembly centres in Romania and at 4 abattoirs in Italy over an 8 month period in 2008.

Results:A total of 1519 horses in 64 separate shipments were observed in Romania prior to transport of which 212 horses were deemed unfit for transport and only 3 shipments (5%) complied with Council Regulation (EC) no. 1/2005 with respect to both horse and vehicle compliance. The destination most commonly stated for the horses from these assembly centres was Italy. A total of 1271 horses in 63 separate shipments were observed after transport in Italy, of which 86 horses in 4 shipments had also been observed prior to transport in Romania. The majority of the horses observed at these abattoirs originated from Poland (51%) and Romania (44%). On arrival in Italy at the time of unloading, 471 of 1271 horses (37%) were deemed unfit for transport in accordance with Council Regulation (EC) no. 1/2005 and none of the shipments were compliant with respect to both vehicle and horse requirements. An average of 6 horses per shipment (28% of each shipment) had at least one acute injury on arrival in Italy. A significantly higher prevalence of severe injuries and lameness was found in animals on arrival In Italy compared with animals leaving Romania. Horses examined on arrival in Italy were twice as likely to have 1–3 acute contusions or excoriations as horses examined in Romania. There was also a 2‐fold increase in the number of animals deemed unfit for transport.

Conclusion:This study has identified evidence of poor welfare in horses being transported long distances to slaughter, including severe lameness and injuries, and a high level of noncompliance with Council Regulation (EC) no. 1/2005 on the Protection of Animals during Transport.
Approximating the Schur multiplier of certain infinitely presented groups via nilpotent quotients
Authors: Hartung René
Published: August 2010

We describe an algorithm for computing successive quotients of the Schur multiplier M(G) of a group G given by an invariant finite L-presentation. As applications, we investigate the Schur multipliers of various self-similar groups, including the Grigorchuk super-group, the generalized Fabrykowski–Gupta groups, the Basilica group and the Brunner–Sidki–Vieira group.
Design of Electromagnetic Dampers for Aero-Engine Applications
Authors: Tonoli Andrea , Amati Nicola , Bonfitto Angelo , Silvagni Mario , Staples Bernard , Karpenko Evgueni
Published: August 2010

The vibration control of rotors for gas or steam turbines is usually performed using passive dampers when hydrodynamic bearings are not used. In layouts where the rotating parts are supported by rolling bearings, the damping is usually provided by squeeze film dampers. Their passive nature and the variability of their performances with temperature and frequency represent the main disadvantages. Dampers with magnetorheological and electrorheological fluid allow solving only a part of the abovementioned drawbacks. Active magnetic bearings (AMBs) are promising since they are very effective in controlling the vibration of the rotor and offering the possibility of monitoring the rotor’s behavior using their displacement sensors. However they show serious drawbacks related to their stiffness. Electromagnetic dampers seem to be a valid alternative to visco-elastic, hydraulic dampers due to, among the others, the absence of all fatigue and tribology issues resulting from the absence of contact, the small sensitivity to the working environment, the wide possibility of tuning even during operation, the predictability of the behavior, the smaller mass compared with AMBs, and the failsafe capability. The aim of the present paper is to describe a design methodology adopted to develop electromagnetic dampers to be installed in aero-engines. The procedure has been validated using a reduced scale laboratory test rig. The same approach has then been adopted to design the electromagnetic dampers for real civil aircraft engines. The results in terms of achievable vibration reductions, mass, and overall dimensions are hence presented. A trade-off between the various proposed solutions has been carried out evaluating quantitative performance parameters together with qualitative aspects that this “more electric” technology implies.
Effect of Exhaust Gas Temperature Limits on the Peak Power Performance of a Turbocharged Gasoline Engine
Authors: Karnik Amey Y. , Shelby Michael H.
Published: August 2010

Peak power of an engine is typically constrained by the maximum obtainable airflow. This constraint could arise directly from the airflow limitation imposed by the throttle restriction (typical for a naturally aspirated engine), or indirectly from other factors, such as various temperature limits for component protection. In this work, we evaluate the airflow limit for a turbocharged gasoline engine as dictated by the constraints on the turbine inlet temperature. Increasing the limit on the turbine inlet temperature requires the exhaust manifolds and turbine to be made out of more expensive materials that withstand higher temperatures. This expense is justifiable if operating with higher turbine inlet temperature allows noticeably higher power output, and not merely increases the allowable airflow. Experimental data show that under some conditions the increase in airflow does not increase the peak power. The effects of increasing airflow on the peak power and turbine inlet temperatures are systematically analyzed through individual accounting for the different losses affecting the engine torque. The breakdown analysis presented in this work indicates combustion phasing as a major contributing factor to whether increasing the flange temperature limit would increase the peak power.
Proportional Integral Derivative Based Fault Tolerant Control for a Gas Turbine
Authors: Sanchez-Parra Marino , Verde Cristina , Suarez Dionisio A.
Published: August 2010

This paper presents a fault tolerant control switching scheme with embedded fault detection and isolation system for the gas turbine of a combined cycle power plant. Mechanical faults of the turbogenerator are considered as case study. Previous to the control design, the detection and isolation capabilities of the gas turbine are studied by applying structural analysis to a first principles based gas turbine model. As a result, a new sensor was suggested to improve the detectability and isolability with respect to mechanical faults and sensors faults. Furthermore, the active fault tolerant control developed is based on stabilizing families of proportional integral derivative (PID) controllers, which are tuned off-line and the plant switching scheme preserves the stability of the whole closed-loop system, thanks to a careful selection of controller according to fault conditions. Simulation results with nonlinear model show the potential of the procedure.
A Comprehensive Procedure to Estimate the Probability of Extreme Vibration Levels Due to Mistuning
Authors: Chan Y.-J. , Ewins D. J.
Published: August 2010

A new procedure is developed to find the probabilities of extremely high amplification factors in mistuned bladed disk vibration levels, typical of events which occur rarely. While a rough estimate can be made by curve-fitting the distribution function generated in a Monte Carlo simulation, the procedure presented here can determine a much more accurate upper bound and the probabilities of amplification factors near to that bound. The procedure comprises an optimization analysis based on the conjugate gradient method and a stochastic simulation using the importance sampling method. Two examples are provided to illustrate the efficiency of the procedure, which can be 2 or 3 orders of magnitude more efficient than Monte Carlo simulations.
Investigation of Hydrogen Emissions in Partially Premixed Diesel Combustion
Authors: Northrop William F. , Vanderpool Lucas M. , Madathil Praveen V. , Assanis Dennis N. , Bohac Stanislav V.
Published: August 2010

Partially premixed combustion strategies offer many advantages for compression ignition engines. One such advantage for those operating on diesel fuels is the simultaneous reduction in soot and NOx achievable over a wide range of equivalence ratios. Though often not measured in engine experiments, gaseous H2 is a byproduct of incomplete combustion and can be useful for the regeneration of aftertreatment devices. Correlations for the exhaust concentration of H2, mostly derived from experiments with homogeneous spark ignition engines, indicate that it is emitted either in proportion to CO directly or as a function of a pseudowater gas shift equilibrium constant. In this work, H2 is measured over a range of equivalence ratios in a multicylinder diesel engine operating in a partially premixed low temperature combustion (LTC) mode using both low sulfur diesel fuel and soy-based biodiesel. Biodiesel was found to have the same bulk gas emissions of major species including H2 over the range of equivalence ratio in LTC for a constant load and combustion phasing. It also was found that the experimental H2 concentration was near the value predicted by the equilibrium constant for equivalence ratios greater that 0.85 but was increasingly lower for leaner points.
A Pseudo-Rigid-Body Model for Large Deflections of Fixed-Clamped Carbon Nanotubes
Authors: Howell Larry L. , DiBiasio Christopher M. , Cullinan Michael A. , Panas Robert M. , Culpepper Martin L.
Published: August 2010

Carbon nanotubes (CNTs) may be used to create nanoscale compliant mechanisms that possess large ranges of motion relative to their device size. Many macroscale compliant mechanisms contain compliant elements that are subjected to fixed-clamped boundary conditions, indicating that they may be of value in nanoscale design. The combination of boundary conditions and large strains yield deformations at the tube ends and strain stiffening along the length of the tube, which are not observed in macroscale analogs. The large-deflection behavior of a fixed-clamped CNT is not well-predicted by macroscale large-deflection beam bending models or truss models. Herein, we show that a pseudo-rigid-body model may be adapted to capture the strain stiffening behavior and, thereby, predict a CNT’s fixed-clamped behavior with less than 3% error from molecular simulations. The resulting pseudo-rigid-body model may be used to set initial design parameters for CNT-based compliant mechanisms. This removes the need for iterative, time-intensive molecular simulations during initial design phases.
Derivation of Topological Graphs of Some Planar 4DOF Redundant Closed Mechanisms by Contracted Graphs and Arrays
Authors: Lu Yi , Ding Ling , Li Shuyan , Yu Jianping
Published: August 2010

Some planar redundantly closed mechanisms (RCMs) have better dexterity, less singular configuration, and higher stiffness. In this paper, the derivation of valid topology graphs (TGs) of some planar four degrees of freedom (4DOF) RCMs is studied based on the contracted graph (CG), arrays, and topology graph with digits (DTG). First, some CGs without any binary links are constructed for the planar 4DOF RCMs, some curves with only binary links are distributed over CGs, and some valid TGs of the planar 4DOF RCMs are derived. Second, a complicated derivation of TG is transformed into an easy derivation of array and DTG, and some programs are compiled in VISUAL BASIC; all valid arrays corresponding to nonisomorphic TGs are derived, and some invalid arrays corresponding to the isomorphic TGs and invalid TGs are determined and removed by the compiled programs. Third, many valid TGs of the planar 4DOF RCMs with various basic links are derived from valid arrays and DTGs. Finally, some application examples are illustrated.
A 3-ṞPR Parallel Mechanism With Singularities That are Self-Motions
Authors: Rakotomanga Novona , Bonev Ilian A.
Published: August 2010

The Cartesian workspace of most three-degree-of-freedom parallel mechanisms is divided by Type 2 (also called parallel) singularity surfaces into several regions. Accessing more than one such region requires crossing a Type 2 singularity, which is risky and calls for sophisticated control strategies. Some mechanisms can still cross these Type 2 singularity surfaces through “holes” that represent Type 1 (also called serial) singularities only. However, what is even more desirable is if these Type 2 singularity surfaces were curves instead. Indeed, there exists at least one such parallel mechanism (the agile eye) and all of its singularities are self-motions. This paper presents another parallel mechanism, a planar one, whose singularities are self-motions. The singularities of this novel mechanism are studied in detail. While the Type 2 singularities in the Cartesian space still constitute a surface, they degenerate into lines in the active-joint space, which is the main result of this paper.
Instant Center Based Kinematic Formulation for Planar Wheeled Platforms
Authors: Kulkarni Amit , Tesar Delbert
Published: August 2010

For a general J wheeled mobile platform capable of up to three-degrees-of-freedom planar motion, there are up to two J independent input parameters yet the output of the platform is completely represented by three independent variables. This leads to an input parameter resolution problem based on operational criteria, which are in development just as they have been developed for n input manipulator systems. To resolve these inputs into a meaningful decision structure means that all motions at the wheel attachment points must have clear physical meaning. To this effect, we propose a methodology for kinematic modeling of multiwheeled mobile platforms using instant centers to efficiently describe the motion of all system points up to the nth order using a generalized algebraic formulation. This is achieved by using a series of instant centers (velocity, acceleration, jerk, and jerk derivative), where each point in the system has a motion property with its magnitude proportional to the radial distance of the point from the associated instant center and at a constant angle relative to that radius. The method of instant center provides a straightforward and physically intuitive way to synthesize a general order planar motion of mobile platforms. It is shown that a general order motion property of any point on a rigid body follows two properties, namely, directionality and proportionality, with respect to the corresponding instant center. The formulation presents a concise expression for a general order motion property of a general point on the rigid body with the magnitude and direction separated and identified. The results are summarized for up to the fifth order motion in the summary table. Based on the initial formulation, we propose the development of operational criteria using higher order properties to efficiently synthesize the motion of a J wheeled mobile platform.
Redundancy Resolution Using Tractrix—Simulations and Experiments
Authors: Ravi V. C. , Rakshit Subrata , Ghosal Ashitava
Published: August 2010

Hyper-redundant robots are characterized by the presence of a large number of actuated joints, a lot more than the number required to perform a given task. These robots have been proposed and used for many applications involving avoiding obstacles or, in general, to provide enhanced dexterity in performing tasks. Making effective use of the extra degrees-of-freedom or resolution of redundancy has been an extensive topic of research and several methods have been proposed in literature. In this paper, we compare three known methods and show that an algorithm based on a classical curve, called the tractrix, leads to a more “natural” motion of the hyper-redundant robot with the displacements diminishing from the end-effector to the fixed base. In addition, since the actuators nearer the base “see” a greater inertia due to the links farther away, smaller motion of the actuators nearer the base results in better motion of the end-effector as compared with other two approaches. We present simulation and experimental results performed on a prototype eight-link planar hyper-redundant manipulator.
Geometric Determination of the Interference-Free Constant-Orientation Workspace of Parallel Cable-Driven Mechanisms
Authors: Perreault Simon , Cardou Philippe , Gosselin Clément M. , Otis Martin J.-D.
Published: August 2010

The increasing use of parallel cable-driven mechanisms calls for a better understanding of their behavior and highly efficient algorithms to attenuate their drawbacks at the design stage. One of these drawbacks is the high probability of mechanical interferences between the moving parts of the mechanism. In this paper, the phenomenon is described under the assumption that a cable is a line segment in space. When a mechanical contact occurs between two cables or between a cable and an edge of the end effector, these entities necessarily lie in the same plane, and then the three-dimensional problem becomes two-dimensional. This fact is used to simplify the equations, and leads to exhaustive descriptions of the associated interference loci in the constant-orientation workspace of a cable-driven mechanism. These results provide a fast method to graphically represent all interference regions in the manipulator workspace, given its geometry and the orientation of its end effector.
Workspace Decomposition Based Dimensional Synthesis of a Novel Hybrid Reconfigurable Robot
Authors: Sun Tao , Song Yimin , Li Yonggang , Zhang Jun
Published: August 2010

A novel 5-axis hybrid reconfigurable robot named Tricept-IV, including one 4-degree-of-freedom (4DOF) hybrid module and one 2DOF end effector, is investigated. Compared with extensive research that has been pursued for the parallel kinematic machines such as Tricept, Sprint Z3 Head, and so on, the hybrid kinematic machines have not adequately been studied. This paper demonstrates a method of workspace decomposition applied in the dimensional synthesis of a 4DOF hybrid module, which is the underlying architecture of the newly invented robot. This paper starts with an introduction of the Tricept-IV robot. After dividing the 4DOF hybrid module into one position-orientation coupling (POC) subsystem and one position-feed (PF) subsystem, its workspace is decomposed into POC and PF subspaces accordingly, and then the inverse position problem may be solved by means of one prejudgment method. Furthermore, the Jacobian matrix of the POC subsystem is obtained by the screw theory so as to formulate its kinematic performance index. Finally, the dimensional synthesis based on workspace decomposition of the hybrid module is carried out by taking a global view of the dimensional synthesis of these two subsystems.
Static Joint Torque Determination of a Human Model for Standing and Seating Tasks Considering Balance
Authors: Yang Jingzhou (James) , Kim Joo H.
Published: August 2010

Estimation of the risk of injury to human different joints during occupational tasks plays an important role to reduce injuries before the operators carry out the tasks. This paper presents a methodology for determining the static joint torques of a human model considering balance for both standing and seating tasks such as weight lifting, material handling, and seated operating tasks in the assembly line. A high fidelity human model has been developed, and recursive dynamics has been used to formulate the static equation of motion. An alternative and efficient formulation of the zero-moment point for static balance and the approximated (ground/seat) support reaction forces/moments are derived from the resultant reaction loads, which includes the gravity and externally applied loads. The proposed method can be used for both standing and seating tasks for assessing the stability/balance of the posture. The proposed formulation can be beneficial to physics-based simulation of humanoids and human models. Also, the calculated joint torques can be considered as an indicator to assess the risks of injuries when human models perform various tasks. The computational time for each case is close to 0.015 s.
Thermohydraulic Study of a Flat Plate Heat Pipe by Means of Confocal Microscopy: Application to a 2D Capillary Structure
Authors: Lips Stéphane , Lefèvre Frédéric , Bonjour Jocelyn
Published: August 2010

Thermal and hydrodynamic experimental results of a flat plate heat pipe (FPHP) are presented. The capillary structure is made of crossed grooves machined in a copper plate. The shape of the liquid-vapor interface in this type of capillary structure—that can also be viewed as an array of posts—is studied theoretically and experimentally. A confocal microscope is used to visualize the liquid-vapor interface and thus the capillary pressure field in the system. These hydrodynamic measurements, coupled to temperature measurements on the FPHP wall, are used to estimate the permeability and the equivalent thermal conductivity of the capillary structure filled with methanol or FC72. These parameters are obtained from a comparison between the experimental data and an analytical model. Finally, the model is used to compare the draining capability of crossed grooves with that of longitudinal grooves.
Enhanced Convective Heat Transfer in Nongas Generating Nanoparticle Thermites
Authors: Dean S. W. , Pantoya M. L. , Gash A. E. , Stacy S. C. , Hope-Weeks L. J.
Published: August 2010

Flame propagation and peak pressure measurements were taken of two nanoscaled thermites using aluminum (Al) fuel and copper oxide (CuO) or nickel oxide (NiO) oxidizers in a confined flame tube apparatus. Thermal equilibrium simulations predict that the Al+CuO reaction exhibits high gas generation and, thus, high convective flame propagation rates while the Al+NiO reaction produces little to no gas and, therefore, should exhibit much lower flame propagation rates. Results show flame propagation rates ranged between 200 m/s and 600 m/s and peak pressures ranged between 1.7 MPa and 3.7 MPa for both composites. These results were significantly higher than expected for the Al+NiO, which generates virtually no gas. For nanometric Al particles, oxidation has recently been described by a melt-dispersion oxidation mechanism that involves a dispersion of high velocity alumina shell fragments and molten Al droplets that promote a pressure build-up by inducing a bulk movement of fluid. This mechanism unique to nanoparticle reaction may promote convection without the need for additional gas generation.
On Variance-Reduced Simulations of the Boltzmann Transport Equation for Small-Scale Heat Transfer Applications
Authors: Hadjiconstantinou Nicolas G. , Radtke Gregg A. , Baker Lowell L.
Published: August 2010

We present and discuss a variance-reduced stochastic particle simulation method for solving the relaxation-time model of the Boltzmann transport equation. The variance reduction, achieved by simulating only the deviation from equilibrium, results in a significant computational efficiency advantage compared with traditional stochastic particle methods in the limit of small deviation from equilibrium. More specifically, the proposed method can efficiently simulate arbitrarily small deviations from equilibrium at a computational cost that is independent of the deviation from equilibrium, which is in sharp contrast to traditional particle methods. The proposed method is developed and validated in the context of dilute gases; despite this, it is expected to directly extend to all fields (carriers) for which the relaxation-time approximation is applicable.
Numerical Analysis of Interaction Between Inertial and Thermosolutal Buoyancy Forces on Convective Heat Transfer in a Lid-Driven Cavity
Authors: Senthil kumar D. , Murugesan K. , Gupta Akhilesh
Published: August 2010

In this paper, results on double diffusive mixed convection in a lid-driven cavity are discussed in detail with a focus on the effect of interaction between fluid inertial force and thermosolutal buoyancy forces on convective heat and mass transfer. The governing equations for the mathematical model of the problem consist of vorticity transport equation, velocity Poisson equations, energy equation and solutal concentration equation. Numerical solution for the field variables are obtained by solving the governing equations using Galerkin’s weighted residual finite element method. The interaction effects on convective heat and mass transfer are analyzed by simultaneously varying the characteristic parameters, 0.1<Ri<5, 100<Re<1000, and buoyancy ratio (N), −10<N<10. In the presence of strong thermosolutal buoyancy forces, the increase in fluid inertial force does not make significant change in convective heat and mass transfer when the thermal buoyancy force is smaller than the fluid inertial force. The fluid inertial force enhances the heat and mass transfer only when the thermal buoyancy force is either of the same magnitude or greater than that of the fluid inertial force. The presence of aiding solutal buoyancy force enhances convective heat transfer only when Ri becomes greater than unity but at higher buoyancy ratios, the rate of increase in heat transfer decreases for Re=400 and increases for Re=800. No significant change in heat transfer is observed due to aiding solutal buoyancy force for Ri≤1 irrespective of the Reynolds number.
Radiation and Conduction in an Isotropic Scattering Rectangular Medium With One Semitransparent and Diffusely Reflecting Boundary
Authors: Luo Jian-Feng , Yi Hong-Liang , Chang Sheng-Li , Tan He-Ping
Published: August 2010

Using the ray tracing-node analyzing method, the 2D transient coupled radiative and conductive heat transfer in a rectangular semitransparent medium is investigated. The rectangular medium has one semitransparent and diffuse boundary (the other three boundaries are black) and is isotropically scattering. The transient differential energy equation is discretized by the fully implicit finite difference method, and the radiative source term of the energy equation is expressed by the radiative transfer coefficients (RTCs). The integrality and reciprocity relationships of the RTCs without considering scattering for the 2D physical model are discovered, which are much different from those for the 1D case. When solving the isotropic scattering RTCs, the RTCs without considering scattering are normalized at first, and then the normalized RTCs are used to trace the energy scattered by control volumes. Finally, the isotropic scattering RTCs are solved by reverse calculation. The Patankar’s linearization method is used to linearize the radiative source term and the opaque boundary conditions, and the boundary conditions are dealt with an additional source term method. The alternating direction implicit method is applied to solve the nominal linearized equations. The effects of scattering albedo, extinction coefficient, refractive index, etc., on transient coupled heat transfer are studied. The study shows that when the extinction coefficient is so small, the increase in scattering albedo can intensify the cooling of the three black surfaces of the rectangular medium.
Scale-Up and Generalization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation
Authors: Sahray D. , Ziskind G. , Letan R.
Published: August 2010

This paper provides further insight in heat transfer from horizontal-base pin fin heat-sinks in free convection of air. The main objective is to assess the effect of base size, and this with regard to the effects of fin height and fin population density studied in a previous work (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13). To this end, experimental and numerical investigations are performed with sinks of different base sizes. The sinks are made of aluminum, with no contact resistance between the base and the fins, and are heated using foil electrical heaters. In the corresponding numerical study, the sinks and their environment are modeled using the FLUENT 6.3 software. In the experiments, sink bases of 100×100 mm2 and 200×200 mm2 are used, while in the numerical study sinks of 50×50 mm2 are investigated, too. In addition to the sinks with exposed, free edges (Sahray, D., et al., 2010, “Study and Optimization of Horizontal-Base Pin-Fin Heat Sinks in Natural Convection and Radiation,” ASME J. Heat Transfer, 132(012503), pp. 1–13), the same sinks are explored also with their edges blocked. This is done in order to exclude the edge effect, thus making it possible to estimate heat transfer from a sink of an “infinite” base size. Heat-transfer enhancement due to the fins is assessed quantitatively and analyzed for various base sizes and fin heights. The effect of fin location in the array on its contribution to the heat-transfer rate from the sink is analyzed. By decoupling convection from radiation, a dimensional analysis of the results for natural convection is attempted. Interdependence of the base size and fin height effects on the heat transfer is demonstrated. A correlation that encompasses all the cases studied herein is obtained, in which the Nusselt number depends on the Rayleigh number, which uses the “clear” spacing between fins as the characteristic length, and on the dimensions of the fins and the base.
Vadasz Number Influence on Vibration in a Rotating Porous Layer Placed Far Away From the Axis of Rotation
Authors: Govender S.
Published: August 2010

We consider vibration effects on the classical Rayleigh–Be’nard problem and the classical Vadasz (1994, “Stability of Free Convection in a Narrow Porous Layer Subject to Rotation,” Int. Commun. Heat Mass Transfer, 21, pp. 881–890) problem, which includes rotation of a vertical porous layer about the z-axis. In particular, we focus on the influence of the Vadasz number on vibration for small to moderate and large Vadasz numbers. For small to moderate Vadasz numbers, we develop an analogy between the Vadasz problem (Vadasz, 1994, “Stability of Free Convection in a Narrow Porous Layer Subject to Rotation,” Int. Commun. Heat Mass Transfer, 21, pp. 881–890) placed far away from the axis of rotation and classical Rayleigh–Be’nard problem, both of which include the effects of vibration. It is shown here that the stability criteria are identical to the Rayleigh–Be’nard problem with vibration when g∗=ω∗2X0∗. The analysis for the large Vadasz number scaling indicates that a frozen time approximation is appropriate where the effect of vibration is modeled as small variations in the Rayleigh number definition.
Combined Effects of Temperature and Velocity Jump on the Heat Transfer, Fluid Flow, and Entropy Generation Over a Single Rotating Disk
Authors: Arikoglu A. , Komurgoz G. , Ozkol I. , Gunes A. Y.
Published: August 2010

The present work examines the effects of temperature and velocity jump conditions on heat transfer, fluid flow, and entropy generation. As the physical model, the axially symmetrical steady flow of a Newtonian ambient fluid over a single rotating disk is chosen. The related nonlinear governing equations for flow and thermal fields are reduced to ordinary differential equations by applying so-called classical approach, which was first introduced by von Karman. Instead of a numerical method, a recently developed popular semi numerical-analytical technique; differential transform method is employed to solve the reduced governing equations under the assumptions of velocity and thermal jump conditions on the disk surface. The combined effects of the velocity slip and temperature jump on the thermal and flow fields are investigated in great detail for different values of the nondimensional field parameters. In order to evaluate the efficiency of such rotating fluidic system, the entropy generation equation is derived and nondimensionalized. Additionally, special attention has been given to entropy generation, its characteristic and dependency on various parameters, i.e., group parameter, Kn and Re numbers, etc. It is observed that thermal and velocity jump strongly reduce the magnitude of entropy generation throughout the flow domain. As a result, the efficiency of the related physical system increases. A noticeable objective of this study is to give an open form solution of nonlinear field equations. The reduced recurative form of the governing equations presented gives the reader an opportunity to see the solution in open series form.
Ti/Au Ohmic contacts to indium zinc oxide thin films on paper substrates
Authors: Khanna R. , Douglas E. A. , Norton D. P. , Pearton S. J. , Ren F.
Published: August 2010

Low resistance Ohmic contacts using Ti/Au metallization on n-type amorphous indium zinc oxide (IZO) (n∼5×1020 cm−3) deposited on paper substrates are reported. The minimum specific contact resistivity of 8×10−7 Ω cm2 was achieved on IZO films both as-deposited and for annealing temperatures of up to 125 °C. The contact resistance increased to 4×10−6 Ω cm2 at 175 °C. The sheet resistance was found to vary from 24 to 17 Ω/sq, and the transfer resistance was ∼0.045 Ω mm for the as-deposited and low temperature annealed samples. The contact resistance was independent of measurement temperature, indicating that field emission plays a dominant role in the current transport. Such Ohmic contacts achieved with little or no annealing are important for paper based electronics requiring low temperature processing (<200 °C).
A RAPID METHOD OF TOTAL LIPID EXTRACTION AND PURIFICATION
Authors: Bligh E. G. , Dyer W. J.
Published: August 2010

Lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials. The entire procedure can be carried out in approximately 10 minutes; it is efficient, reproducible, and free from deleterious manipulations. The wet tissue is homogenized with a mixture of chloroform and methanol in such proportions that a miscible system is formed with the water in the tissue. Dilution with chloroform and water separates the homogenate into two layers, the chloroform layer containing all the lipids and the methanolic layer containing all the non-lipids. A purified lipid extract is obtained merely by isolating the chloroform layer. The method has been applied to fish muscle and may easily be adapted to use with other tissues.
PURIFICATION AND PROPERTIES OF PHOSPHOGLUCOSE ISOMERASE FROM ASPERGILLUS NIGER
Authors: Singh Kartar
Published: August 2010

Phosphoglucose isomerase from Aspergillus niger was purified about fiftyfold by ammonium sulphate fractionation and treatment with calcium phosphate gel. The properties and kinetics of the enzyme are described. The enzyme resembled the muscle phosphoglucose isomerase in not requiring metal ions for activation but differed in showing no inhibition with phosphate. The enzyme showed maximum activity between pH 7.8 to 8.0 as compared with the optimum pH 9.0 shown by the muscle enzyme.
ACID-LABILE PHOSPHATE CONTENT OF INCUBATED BRAIN SLICES
Authors: Pappius Hanna M. , Johnson Dorothy McLean , Elliott K. A. C.
Published: August 2010

During aerobic incubation of brain cortex slices in glucose-containing medium at 38° the pyrophosphate content of the tissue increases rapidly for 15 minutes and then more slowly. The creatine phosphate content increases rapidly during the first 5 minutes and then falls. Anaerobically, the pyrophosphate falls during the first 30 minutes; the creatine phosphate tends to rise initially and then falls to a lower level than that found aerobically. In the absence of glucose and oxygen the levels of both substances fall rapidly to low levels but can be raised again by aerobiosis in the presence of glucose. In the absence of glucose and oxygen in ice-cold medium, or at 38° in the absence of any medium, the levels of pyrophosphate and creatine phosphate are preserved. More inorganic phosphate is produced when slices are incubated than can be accounted for by breakdown of acid-labile phosphate compounds.It is shown that the initial rate of anaerobic glycolysis by slices which have been subjected to various pretreatments is strongly correlated with the pyrophosphate content of the tissue.The failure of slices to concentrate potassium when immersed in sodium-free media is not due to failure to maintain pyrophosphate levels.
ZONE ELECTROPHORESIS OF TOBACCO MOSAIC VIRUS
Authors: Townsley P. M.
Published: August 2010

An apparatus is described for the preparative zone electrophoresis of tobacco mosaic virus in agar gel. The isolated virus does not have any detectable ribonuclease activity.
THE CATALYSIS OF ASCORBIC ACID OXIDATION BY COPPER AND ITS COMPLEXES WITH AMINO ACIDS, PEPTIDES, AND PROTEINS
Authors: Scaife J. F.
Published: August 2010

The oxidation of solutions of ascorbic acid catalyzed by copper and the copper complexes of amino acids, peptides, and proteins has been investigated by manometric and chemical means. The copper-containing solutions were prepared by equilibration with the sparingly soluble salt malachite. The catalytic activity of the complexed copper was found to be dependent upon the type of complexing molecule. For amino acids the more firmly bound copper atoms tended to be the best catalysts. The catalytic activity of the copper complexed to several glycine peptides was approximately one half of the mean value of that of the copper complexed to amino acids. The catalytic activity of copper complexed to bovine plasma albumen and pepsin was lower than that of copper complexed with amino acids or peptides. The more firmly bound copper atoms on pepsin showed a higher catalytic activity than the mean value for all the complexed copper atoms. Sodium chloride markedly reduced the catalytic activity of both free copper and complexed copper. In the absence of sodium chloride free copper was 10 times as effective a catalyst as copper complexed to glycine. In the presence of 0.178 M sodium chloride the complexed copper was twice as effective as free copper.
A NOTE ON THE NON-COMMUTATIVE LAPLACE–VARADHAN INTEGRAL LEMMA
Authors: DE ROECK W. , MAES CHRISTIAN , NETOČNÝ KAREL , REY-BELLET LUC
Published: August 2010

We continue the study of the free energy of quantum lattice spin systems where to the local Hamiltonian H an arbitrary mean field term is added, a polynomial function of the arithmetic mean of some local observables X and Y that do not necessarily commute. By slightly extending a recent paper by Hiai, Mosonyi, Ohno and Petz [10], we prove in general that the free energy is given by a variational principle over the range of the operators X and Y. As in [10], the result is a non-commutative extension of the Laplace–Varadhan asymptotic formula.
THE METHOD OF MULTI-SCALE ASYMPTOTIC EXPANSIONS AND ITS CORRESPONDING FINITE ELEMENT ALGORITHM FOR THE PROBLEM OF HEAT EXCHANGE IN COMPOSITE PLANE WALL
Authors: HE WEN-MING , GUAN XIAO-FEI , TAN JIAO
Published: August 2010

In this paper, we discuss the problem of heat exchange in composite plane wall whose heat transmitting coefficient is not a locally periodic function. For that problem, we present a method of multiscale asymptotic expansions and then propose its corresponding FE algorithm. Of course, we give comprehensive theoretical analysis for the FE algorithm. Finally, we use numerical experiments to investigate them.
GENERALIZED PROJECTIVE SYNCHRONIZATION OF CHAOTIC NEURAL NETWORKS: OBSERVER-BASED APPROACH
Authors: WANG XING YUAN , MENG JUAN
Published: August 2010

In this paper, the generalized projective synchronization of chaotic neural networks is investigated. Based on the modified nonlinear state observer algorithm and the pole placement technique, a synchronization scheme is designed. The generalized projective synchronization of different chaotic neural networks can be achieved by using the proposed method. Numerical simulations further demonstrate the effectiveness of the proposed scheme.
VORTICES IN BRAIN WAVES
Authors: FREEMAN WALTER J. , VITIELLO GIUSEPPE
Published: August 2010

Interactions by mutual excitation in neural populations in human and animal brains create a mesoscopic order parameter that is recorded in brain waves (electroencephalogram, EEG). Spatially and spectrally distributed oscillations are imposed on the background activity by inhibitory feedback in the gamma range (30–80 Hz). Beats recur at theta rates (3–7 Hz), at which the order parameter transiently approaches zero and microscopic activity becomes disordered. After these null spikes, the order parameter resurges and initiates a frame bearing a mesoscopic spatial pattern of gamma amplitude modulation that governs the microscopic activity, and that is correlated with behavior. The brain waves also reveal a spatial pattern of phase modulation in the form of a cone. Using the formalism of the dissipative many-body model of brain, we describe the null spike as a singularity, the following amplitude pattern as a ground state, and the phase cone as the manifestation of a stabilizing vortex.
DYNAMICS OF SUPER-SECH SOLITONS IN OPTICAL FIBERS
Authors: GREEN PATRICE , MILOVIC DANIELA , SARMA AMARENDRA K. , LOTT DAWN A. , BISWAS ANJAN
Published: August 2010

This paper obtains the parameter dynamics of super-sech optical solitons propagating through optical fibers. The variational principle is applied to obtain these parameter dynamics. Both polarization preserving fibers as well as birefringent fibers are studied in this paper. The study is then finally extended to the case of DWDM systems. The adiabatic parameter dynamics of soliton parameters is then obtained in the presence of perturbation terms. The numerical simulations are also obtained to complete the analysis.
NONLINEAR OPTICAL WAVEGUIDE SPECTROSCOPY OF POLY(3-BUTYLTHIOPHENE)
Authors: JAHJA MOHAMAD , BUBECK CHRISTOPH
Published: August 2010

We prepared thin films of the conjugated polymer poly(3-butylthiophene) by spin-coating and performed transmission and reflection spectroscopy to characterize the dispersion of linear refractive index and absorption coefficient at in-plane polarization. Slab waveguides of this regiorandom polythiophene derivative have mode propagation losses smaller than 1 dB/cm at wavelengths larger than 1000 nm. We determined the nonlinear refractive index and two-photon absorption of slab waveguides by means of intensity-dependent prism coupling using picosecond laser pulses in the range 700–1300 nm. These data yield the dispersion of the figures of merit, which appear promising for all-optical waveguide switching at wavelengths larger than 1200 nm.
SINGLE MODE ERBIUM YTTERBIUM-DOPED FIBER LASER WITH MULTIMODE PUMPING
Authors: HARUN S. W. , AHMAD H. , LIM E. L. , ALAM S. U. , RICHARDSON D. J.
Published: August 2010

An efficient and stable laser action from a double-clad erbium/ytterbium-doped fiber (EYDF) is demonstrated using a fiber Bragg grating at room temperature. The fiber laser operates at wavelength of 1552.3 nm with a slope efficiency of 38% when pumped by multi-mode 915 nm laser diodes. However, the slope efficiency is higher in the EYDF laser configured with double-sided output due to the high splicing loss between the multi-mode combiner and double-clad EYDF. The laser also has a spectral bandwidth of 0.2 nm and signal to noise ratio of more than 25 dB. The threshold power to achieve lasing is measured to be approximately 500 mW for this laser.