bluuebunny/crossref_metadata_2025 huggingface dataset:
Future employment promises as rent seeking in representative government
Authors: Troy Gibson M.
Published: January 2003

Researchers of legislative behavior have attempted to explain the decisions of legislators for some time. Public choice scholars have argued that legislators will “sell” political favors in exchange for some from of interest group payment that is thought to benefit the legislator's electoral ambitions. Yet, legislators do not appear to receive the full value of their political favor in these exchanges. That is, the value of the policies offered appears to exceed the price paid by interest groups in the form of campaign contributions, speaking honoraria and other material payments. This imbalance has led some scholars to discount theories that explain legislative behavior motivated by material gain. However, to the extent that legislators value post‐elective employment opportunities, interest groups have an incentive to use the offer of future employment as a payment for present legislative influence. In this sense, perhaps a large portion of the difference in payments can be accounted for in the post‐elective employment careers of elected politicians. In this paper, I explore and explain this theory using a political market model and attempt to identify several attributes that I believe will be common among “prospect‐legislators” whose behavior is principally motivated by concerns with post‐elective life.
Norms for evaluating economic globalization
Authors: Gaburro Giuseppe , O'Boyle Edward J.
Published: January 2003

This article examines experience with global financial integration to identify norms for evaluating economic globalization. There are two perspectives regarding globalization: mainstream economics and personalist economics. The first perspective regards itself as value‐free even though its premises originate in individualism and utilitarianism. The second perspective originates in personalism and finds no fault with being value‐laden because there is no other way to proceed in evaluating economic globalization. Mainstream economics brings to bear a few principles from positive economics. Personalist economics employs a larger set of principles from normative economics. The authors hold fast to personalist economics as more relevant to evaluating economic globalization properly. Our argument rests on principles from personalist economics and two other sources: Universal Declaration of Human Rights; and John Paul II's public statements. We intend to contribute to the discourse on globalization using recent experience regarding financial integration to refine the norms for evaluating economic globalization.
Transfers targeting the global environment – benefits for whom?
Authors: Nielsen Uffe
Published: January 2003

Taking departure in the premise that donor and recipient priorities differ with regard to the marginal costs and benefits associated with attacking global environmental externalities, and hence the relative importance attached to the global environment, this paper seeks to scrutinize specific global environmental transfer mechanisms in the light of proposed definitions of global environmental assistance and global environmental compensation. It is argued that most global environmental transfer mechanisms possess distinct compensatory elements, and that additionality of these transfers is essential in order to ensure that existing development assistance is not crowded out. Specifically, this should be achieved either directly through separation of funds for global environmental and local developmental purposes or indirectly through increased considerations for local development objectives directly in global environmental transfer design.
Why are Kalecki's rentiers so boom tired?
Authors: Potts Nick
Published: January 2003

To many economists, not to mention all central bankers, inflation is considered to be public enemy number one. This paper seeks to understand why inflation should be so despised. To escape from simultaneous restrictions a temporal single system (TSS) approach is employed. Firstly a simple illustration of the TSS approach is considered. In order to focus on distributional issues a positive wage and a class of rentiers are built in. Rentiers hold money stocks, past accumulated value in money terms. Rentiers are assumed to lend to productive capitalists, i.e. we have finance capital. Once we build in money stocks we find that appropriate price increases can potentially hide the effect of falling exploitation of labour, transferring the cost of reduced exploitation from productive capitalists to rentiers. Finally, conclusions are drawn.
The right to a living in the international economy
Authors: Richards Donald G.
Published: January 2003

Since the arrival of the World Trade Organization (WTO) in 1995 a number of side agreements have also been negotiated that seek further rationalization of the emerging global economy. Prominent among these is the agreement on trade‐related intellectual property rights (TRIPS). Enforcement of the TRIPS agreement would involve the multilateral trade sanctions mechanism of the WTO. By contrast, proponents advocating a parallel international agreement guaranteeing adequate protections for workers – trade‐related international labor standards (TRILS) – have not met with success. This paper examines how traditional justificatory arguments for the property rights might apply to the question of workers’ rights in the international economy. It is found that such arguments apply quite well to the right of access to a “decent living”. It is then investigated how a TRILS agreement administered and enforced by the WTO's disputes settlements mechanism might advance these rights.
Crisis management in Belgium: the case of Coca‐Cola
Authors: Johnson Victoria , Peppas Spero C.
Published: January 2003

Belgium was still reeling from fears over mad cow disease and from the news that the carcinogen, dioxin, had been introduced inadvertently into animal feed, when yet another health crisis rocked it. This new crisis was precipitated by consumer complaints about an irregular taste and smell in bottled soft drinks and by reports that more than 100 consumers had become ill after noticing an odour on the outside of canned soft drinks. As a result, The Coca‐Cola Company, under instructions from the Belgian Health Ministry, withdrew its trade‐marked products from the Belgian market. The effects of this crisis were felt not only within Europe, but also in countries as far away as Japan and India. Subsequently, the company identified specific production and distribution problems which could have contributed to the health crisis. Pursuant to the Ministry’s order, the company took immediate steps to remedy those problems, and the Ministry’s ban was lifted. In addition, an aggressive marketing campaign was launched in an effort to regain consumer trust, confidence, and market share. Nevertheless, this incident resulted in substantial financial costs to The Coca‐Cola Company and in considerable damage to its global image and reputation.
Communicating sensitive business issues: Part 1
Authors: Dickson David A. , Rainey Seanenne , Hargie Owen D.W.
Published: January 2003

This is the first of a two‐part article reporting the results of a study which investigated communication and relationships in the workplaces of four large organizations in Northern Ireland, two in the public and two in the private sector. A central purpose of the research was to evaluate suitable methods for auditing relationships among staff. Based on a review of the apposite literature on organizational and relational communication, the techniques finally selected as holding out most promise were the focus group approach, retrospective interview technique, social network analysis (SNA), and critical incident technique (CIT). Part 1 evaluates the first two of these techniques in terms of their effectiveness and efficiency in generating rich data enabling sharp insights to be gained of the types of association that typify those who share a work environment. SNA and CIT are similarly dealt with in Part 2, where recommendations for using qualitative and quantitative methods for auditing internal relationships are also offered.
The use of balanced scorecards in the strategic management of corporate communication
Authors: Ritter Michael
Published: January 2003

This article introduces the balanced scorecard model from Kaplan and Norton and makes a proposition about its application on communications by showing the case of the Corporate Relations & Communications division of Siemens Corporation in Argentina.
The policy laboratory for sustainable development
Authors: Glasbergen Pieter , Smits Ruud
Published: January 2003

The emergence of the network society has major consequences for the role played by environmental scientists. They are assumed to be able to contribute to new institutional arrangements for collective action. Through deliberations and organised discourses, environmental scientists are expected to help stakeholders to define common ground for action and the sharing of individual problem solving capacities. This paper discusses the consequences of changes in the nature of decision‐making in the area of sustainability for the concepts and instruments to be used. As a new learning context the policy laboratory is introduced. Special attention is given to three major types of instruments: gaming, interactive methods and group decision support systems.
Localization of Vibration Propagation in Two-Dimensional Systems With Multiple Substructural Modes
Authors: Xie W.-C.
Published: January 2003

Localization of vibration propagation in randomly disordered weakly coupled two-dimensional cantilever-mesh-spring arrays, in which multiple substructural modes are considered for each cantilever, is studied in this paper. A method of regular perturbation for a linear algebraic system is applied to determine the localization factors, which are defined in terms of the angles of orientation and characterize the average exponential rates of growth or decay of the amplitudes of vibration in the given directions. Iterative formulations are derived to determine the amplitudes of vibration of the cantilevers. In the diagonal directions, a transfer matrix formulation is obtained. For a given direction of orientation, the localization behavior is similar to that of a one-dimensional cantilever-spring-mesh chain. The effect of the stiffnesses and the disorder in the stiffnesses of the cantilevers on the localization behavior of the system is investigated.
Wake, Shock, and Potential Field Interactions in a 1.5 Stage Turbine—Part I: Vane-Rotor and Rotor-Vane Interaction
Authors: Miller R. J. , Moss R. W. , Ainsworth R. W. , Harvey N. W.
Published: January 2003

The composition of the time-resolved surface pressure field around a high-pressure rotor blade caused by the presence of neighboring blade rows is investigated, with the individual effects of wake, shock and potential field interaction being determined. Two test geometries are considered: first, a high-pressure turbine stage coupled with a swan-necked diffuser exit duct; secondly, the same high-pressure stage but with a vane located in the downstream duct. Both tests were conducted at engine-representative Mach and Reynolds numbers, and experimental data was acquired using fast-response pressure transducers mounted on the mid-height streamline of the HP rotor blades. The results are compared to time-resolved computational predictions of the flowfield in order to aid interpretation of experimental results and to determine the accuracy with which the computation predicts blade interaction. The paper is split into two parts: the first investigating the effect of the upstream vane on the unsteady pressure field around the rotor (vane-rotor interaction), and the second investigating the effect of the downstream vane on the unsteady pressure field around the rotor (rotor-vane interaction). The paper shows that at typical design operating conditions shock interaction from the upstream blade row is an order of magnitude greater than wake interaction and that with the design vane-rotor inter-blade gap the presence of the rotor causes a periodic increase in the strength of the vane trailing edge shock. The presence of the potential field of the downstream vane is found to affect significantly the rotor pressure field downstream of the Mach one surface within each rotor passage.
Effects of Varying Geometrical Parameters on Boiling From Microfabricated Enhanced Structures
Authors: Ramaswamy C. , Joshi Y. , Nakayama W. , Johnson W. B.
Published: January 2003

The current study involves two-phase cooling from enhanced structures whose dimensions have been changed systematically using microfabrication techniques. The aim is to optimize the dimensions to maximize the heat transfer. The enhanced structure used in this study consists of a stacked network of interconnecting channels making it highly porous. The effect of varying the pore size, pitch and height on the boiling performance was studied, with fluorocarbon FC-72 as the working fluid. While most of the previous studies on the mechanism of enhanced nucleate boiling have focused on a small range of wall superheats (0–4 K), the present study covers a wider range (as high as 30 K). A larger pore and smaller pitch resulted in higher heat dissipation at all heat fluxes. The effect of stacking multiple layers showed a proportional increase in heat dissipation (with additional layers) in a certain range of wall superheat values only. In the wall superheat range 8–13 K, no appreciable difference was observed between a single layer structure and a three layer structure. A fin effect combined with change in the boiling phenomenon within the sub-surface layers is proposed to explain this effect.
Considerations for Using 3-D Pneumatic Probes in High-Speed Axial Compressors
Authors: Coldrick Simon , Ivey Paul , Wells Roger
Published: January 2003

This paper describes preparatory work towards three-dimensional flowfield measurements downstream of the rotor in an industrial, multistage, axial compressor, using a pneumatic pressure probe. The probe is of the steady-state four-hole cobra probe type. The design manufacture and calibration of the probe is described. CFD calculations have been undertaken in order to assess the feasibility of using such a probe in the high-speed compressor environment where space is limited. This includes effects of mounting the probe in close proximity to the downstream stator blades and whether it is necessary to adjust the calibration data to compensate for these effects.
Assessment of Various Film-Cooling Configurations Including Shaped and Compound Angle Holes Based on Large-Scale Experiments
Authors: Dittmar J. , Schulz A. , Wittig S.
Published: January 2003

The demand of improved thermal efficiency and high power output of modern gas turbine engines leads to extremely high turbine inlet temperatures and pressure ratios. Sophisticated cooling schemes including film cooling are widely used to protect vanes and blades from failure and to achieve high component lifetimes. Besides standard cylindrical cooling hole geometry, shaped injection holes are used in modern film cooling applications in order to improve cooling performance and to reduce the necessary cooling air flow. However, complex hole shapes may lead to manufacturing constraints and high costs. This paper evaluates some film-cooling injection geometry with different complexity. The comparison is based on measurements of the adiabatic film-cooling effectiveness and the heat transfer coefficient downstream of the injection location. In total, four different film-cooling hole configurations are investigated: a single row of fanshaped holes with and without a compound injection angle, a double row of cylindrical holes and a double row of discrete slots both in staggered arrangement. All holes are inclined 45 deg with respect to the model’s surface. During the measurements, the influence of coolant blowing ratio is determined. Additionally, the influence of cooling air feeding direction into the fanshaped holes with the compound injection angle is investigated. An infrared thermography measurement system is used for highly resolved mappings of the model’s surface temperature. Accurate local temperature data is achieved by an in-situ calibration procedure with the help of single thermocouples embedded in the test plate. A subsequent finite elements heat conduction analysis takes three-dimensional heat fluxes inside the test plate into account.
The Measurement of Full-Surface Internal Heat Transfer Coefficients for Turbine Airfoils Using a Nondestructive Thermal Inertia Technique
Authors: Nirmalan Nirm V. , Bunker Ronald S. , Hedlund Carl R.
Published: January 2003

A new method has been developed and demonstrated for the non-destructive, quantitative assessment of internal heat transfer coefficient distributions of cooled metallic turbine airfoils. The technique employs the acquisition of full-surface external surface temperature data in response to a thermal transient induced by internal heating/cooling, in conjunction with knowledge of the part wall thickness and geometry, material properties, and internal fluid temperatures. An imaging Infrared camera system is used to record the complete time history of the external surface temperature response during a transient initiated by the introduction of a convecting fluid through the cooling circuit of the part. The transient data obtained is combined with the cooling fluid network model to provide the boundary conditions for a finite element model representing the complete part geometry. A simple 1-D lumped thermal capacitance model for each local wall position is used to provide a first estimate of the internal surface heat transfer coefficient distribution. A 3-D inverse transient conduction model of the part is then executed with updated internal heat transfer coefficients until convergence is reached with the experimentally measured external wall temperatures as a function of time. This new technique makes possible the accurate quantification of full-surface internal heat transfer coefficient distributions for prototype and production metallic airfoils in a totally nondestructive and non-intrusive manner. The technique is equally applicable to other material types and other cooled/heated components.
Some Analytical and Numerical Solutions to Inverse Problems Applied to Optimizing Phase-Transformation Tracking in Gas Quenching
Authors: Vynnycky Michael , Ferrari Je´ro^me , Lior Noam
Published: January 2003

A transient inverse heat conduction problem focused on gas quenching of steel plates and rings is posed and solved, both analytically and numerically. The quenching objective is to calculate the transient convective heat transfer coefficient which would produce an optimized phase transformation cooling curve. The governing nonlinear heat equation is nondimensionalised, and a small parameter, the reciprocal of the Fourier number, is identified. This allows the construction of an analytic solution in the form of an asymptotic series. For higher values of the reciprocal Fourier number, a numerical scheme incorporating the function specification and Keller Box methods is used to generate solutions. Comparison of the results proves favorable, and suggests that for this inverse problem asymptotic methods provide an attractive alternative to solely numerical ones.
Scanning Thermal Wave Microscopy (STWM)
Authors: Kwon Ohmyoung , Shi Li , Majumdar Arun
Published: January 2003

This paper presents a technique, scanning thermal wave microscopy (STWM), which can image the phase lag and amplitude of thermal waves with sub-micrometer resolution by scanning a temperature-sensing nanoscale tip across a sample surface. Phase lag measurements during tip-sample contact showed enhancement of tip-sample heat transfer due to the presence of a liquid film. The measurement accuracy of STWM is proved by a benchmark experiment and comparison to theoretical prediction. The application of STWM for sub-surface imaging of buried structures is demonstrated by measuring the phase lag and amplitude distributions of an interconnect via sample. The measurement showed excellent agreement with a finite element analysis offering the promising prospects of three-dimensional thermal probing of micro and nanostructures. Finally, it was shown that the resolving power of thermal waves for subsurface structures improves as the wavelengths of the thermal waves become shorter at higher modulation frequencies.
Large Eddy Simulation of Constant Heat Flux Turbulent Channel Flow With Property Variations: Quasi-Developed Model and Mean Flow Results
Authors: Dailey Lyle D. , Meng Ning , Pletcher Richard H.
Published: January 2003

Turbulent planar channel flow has been computed for uniform wall heating and cooling fluxes strong enough to cause significant property variations using large eddy simulation. Channels with both walls either heated or cooled were considered, with wall-to-bulk temperature ratios as high as 1.5 for the heated case, and as low as 0.56 for the cooled case. An implicit, second order accurate finite volume scheme was used to solve the time dependent filtered set of equations to determine the large eddy motion, while a dynamic subgrid-scale model was used to account for the subgrid scale effects. Step-periodicity was used based on a quasi-developed assumption. The effects of strong heating and cooling on the flow were investigated and compared with the results obtained under low heating conditions.
On the Quest for the Best Timoshenko Shear Coefficient
Authors: Rubin M. B.
Published: January 2003

Classical Timoshenko beam theory includes a shear correction factor κ which is often used to match natural vibrational frequencies of the beam. In this note, a number of static and dynamic examples are considered which provide a theoretical basis for specifying κ=1. Within the context of Cosserat theory, natural frequencies of the beam can be matched by appropriate specification of the director inertia coefficients with κ=1.
Nusselt Number Behavior on Deep Dimpled Surfaces Within a Channel
Authors: Burgess N. K. , Oliveira M. M. , Ligrani P. M.
Published: January 2003

Experimental results, measured on a dimpled test surface placed on one wall of a channel, are given for a ratio of air inlet stagnation temperature to surface temperature of approximately 0.94, and Reynolds numbers ReH from 12,000 to 70,000. These data include friction factors, local Nusselt numbers, spatially-resolved local Nusselt numbers, and globally-averaged Nusselt numbers. The ratio of dimple depth to dimple print diameter δ/D is 0.3, and the ratio of channel height to dimple print diameter is 1.00. These results are compared to measurements from other investigations with different ratios of dimple depth to dimple print diameter δ/D to provide information on the influences of dimple depth. At all Reynolds numbers considered, local and spatially-resolved Nusselt number augmentations increase as dimple depth increases (and all other experimental and geometric parameters are held approximately constant). These are attributed to: (i) increases in the strengths and intensity of vortices and associated secondary flows ejected from the dimples, as well as (ii) increases in the magnitudes of three-dimensional turbulence production and turbulence transport. The effects of these phenomena are especially apparent in local Nusselt number ratio distributions measured just inside of the dimples, and just downstream of the downstream edges of the dimples.
A Numerical Study of Flow and Heat Transfer in Rotating Rectangular Channels AR=4 With 45 deg Rib Turbulators by Reynolds Stress Turbulence Model
Authors: Al-Qahtani Mohammad , Chen Hamn-Ching , Han Je-Chin
Published: January 2003

Computations were performed to study three-dimensional turbulent flow and heat transfer in stationary and rotating 45 deg ribbed rectangular channels for which experimental heat transfer data were available. The channel aspect ratio (AR) is 4:1, the rib height-to-hydraulic diameter ratio e/Dh is 0.078 and the rib-pitch-to-height ratio P/e is 10. The rotation number and inlet coolant-to-wall density ratios, Δρ/ρ, were varied from 0.0 to 0.28 and from 0.122 to 0.40, respectively, while the Reynolds number was fixed at 10,000. Also, two channel orientations (β=90deg and 135 deg from the rotation direction) were investigated with focus on the high rotation and high density ratios effects on the heat transfer characteristics of the 135 deg orientation. These results show that, for high rotation and high density ratio, the rotation induced secondary flow overpowered the rib induced secondary flow and thus change significantly the heat transfer characteristics compared to the low rotation low density ratio case. A multi-block Reynolds-Averaged Navier-Stokes (RANS) method was employed in conjunction with a near-wall second-moment turbulence closure. In the present method, the convective transport equations for momentum, energy, and turbulence quantities are solved in curvilinear, body-fitted coordinates using the finite-analytic method.
Active Thermal Control of Distributed Parameter Systems With Application to Testing of Packaged IC Devices
Authors: Sweetland Matthew , Lienhard John H.
Published: January 2003

Active control of the die-level temperature is desirable during production testing of high power microprocessors, so as to ensure accurate performance classification. Such control requires that the controlling thermal load time-lead the dissipated thermal load and that it be modulated to account for the distributed thermal capacitance and resistance of the device packaging. The analysis in this paper demonstrates fundamental limits of temperature control for typical devices under test conditions. These limits are identified for specified control power to die power ratios. The effects of test sequence design and device package design on the temperature control limits are also examined. The theory developed can be applied to any thermal control problem where a conductive medium separates the control source from the location where control is desired.
Transient Thermal Modeling of In-Situ Curing During Tape Winding of Composite Cylinders
Authors: Kim Jonghyun , Moon Tess J. , Howell John R.
Published: January 2003

Fully-transient, two-dimensional, heat transfer analysis for the simultaneous tape winding and in-situ curing of composite cylinders is presented. During processing, the orthotropic composites are continuously wound onto an isotropic mandrel and cured simultaneously by infrared (IR) heating. To most efficiently and effectively consider the continual accretion of composite, the model is formulated within a Lagrangian reference frame in which the heating source rotates while the coordinate system and composite are stationary. This enables prediction of composite temperature and degree-of-cure history from the first to last layer. Separate heat conduction equations are formulated for both the mandrel and composite cylinder. The composite cylinder’s outer surface is modeled as a moving boundary due to the accumulated layers. Exothermic heat generation due to the epoxy resin’s chemical reaction is included as a function of temperature and degree of cure. Numerical simulations using a control-volume-based finite difference method are run for a common graphite/epoxy (AS4/3501-6) composite. The Lagrangian approach was found to more accurately predict the in-situ curing temperature and degree-of-cure histories than the previously used, quasi-steady-state Eulerian approaches, which underpredict thermal losses. The model and its computational implementation were verified using analytical solutions and actual experiments. During winding, the top layer’s maximum temperature increases with total number of layers wound, demonstrating that a given incoming prepreg tape’s temperature history evolves with time. Moreover, with appropriate mandrel preheating, the inner layers can reach a very high degree of cure by the end of the winding process, revealing that the mandrel’s initial temperature has a significant effect on the composite’s temperature and degree-of-cure history. Substantial increases in the winding speed have little or no effect on the composite’s temperature history, but can significantly reduce the corresponding degree-of-cure. The development of structurally debilitating residual stresses are an important concern in selecting process parameters, such as winding speed and heating power. Taking advantage of the strong correlation between winding speed and IR heat flux, process windows can be used to guide the selection of manufacturing process parameters. These definitively show that there are thermodynamically imposed limits on how fast the cylinders may be wound and radiatively cured.
Heat Transfer of Impacting Water Mist on High Temperature Metal Surfaces
Authors: Sozbir N. , Chang Y. W. , Yao S. C.
Published: January 2003

Experimental studies were conducted to reveal the heat transfer mechanism of impacting water mist on high temperature metal surfaces. Local heat transfer coefficients were measured in the film-boiling regime at various air velocities and liquid mass fluxes. The test conditions of water mist cover the variations of air velocity from 0 to 50.3 m/s, liquid mass flux from 0 to 7.67 kg/m2s, and surface temperature of stainless steel between 525°C and 500°C. Radial heat transfer distributions were measured at different liquid mass fluxes. The tests revealed that the radial variation of heat transfer coefficients of water mist has a similar trend to the air jet cooling. At the stagnation point, heat transfer coefficient increases with both the air velocity and the liquid mass flux. The convective air heat transfer is consistent with the published correlation in the literature. The heat transfer contribution due to the presence of water increases almost linearly with the liquid mass flux. The total heat transfer coefficient can be established as two separable effects, which is the summation of the heat transfer coefficient of air and of liquid mass flux, respectively. This study shows that with a small amount of water added in the impacting air jet, the heat transfer is dramatically increased. The Leidenfrost temperature under water mist cooling was also measured. The Leidenfrost temperature increased with both the air velocity and the liquid mass flux.
Identifying and Reducing Scaling Problems in Solar Hot Water Systems
Authors: Baker Derek K. , Vliet Gary C.
Published: January 2003

In areas with hard water, scaling can reduce the reliability of solar hot water (SHW) systems. Common reliability problems associated with scaling are both mechanical (collector freeze damage, clogged passages, premature failure of pumps and valves) and thermal (efficiency degradation). A mechanistic and a mathematical scaling rate model are presented. Results from controlled experiments investigating the affect of key water chemistry and heat transfer parameters on the scaling rate are summarized. The implications of these results for designing SHW systems for scaling environments are discussed. Most importantly, indirect systems where the potable water side of the heat exchanger is integrated into the storage tank wall, such as in a wrap-around heat exchanger, are shown to be the most mechanically and thermally reliable systems for scaling environments. A new version of the software SolScale is discussed, which is intended to aid in the design of SHW systems to reduce scaling related reliability problems.
Predictions of External Heat Transfer for Turbine Vanes and Blades With Secondary Flowfields
Authors: Hermanson K. , Kern S. , Picker G. , Parneix S.
Published: January 2003

Detailed heat transfer distributions on the endwall and along the vane/blade surface are essential for component mechanical integrity and life predictions. Due to secondary flows, high gradients in heat transfer are present at the endwall and at the vane or blade surface itself where the passage vortex influences the mainstream flow. This paper documents the benchmarking of three turbulence models: 1) k-ε realizable with wall functions, 2) k-ε realizable with two layer model, and 3) the V2F model for endwall and surface heat transfer and flowfield predictions. Benchmark experimental data from a scaled-up low speed rig for both a stator and rotor geometry are used for comparisons of heat transfer and flowfield. While the k-ε realizable turbulence models give a good prediction of the secondary flow pattern, the heat transfer at the endwall and at the surface is not well predicted due to the inadequate modeling of near wall turbulence. The V2F model gives better agreement with the experiments on the endwall and vane midspan heat transfer is also well predicted, although transition occurs too far upstream on the suction surface. The results from this study represent the feasibility of CFD utilization as a predictive tool for local heat transfer distributions on a vane/blade endwall.
Maximization of Exergy Output From Volumetric Absorption Solar Collectors
Authors: London˜o-Hurtado Alejandro , Rivera-Alvarez Alejandro
Published: January 2003

A model has been developed to study the behavior of Volumetric Absorption Solar Collectors (VASC) and the influence of the design parameters on the performance of the collector. The model’s approach is based on the use of several dimensionless numbers, each of them having a clear physical significance, which play a key role in the analysis of the collector. The model is then used to conduct a thermodynamic optimization of VASC, which gives the optimal design parameters that maximize the exergy output of the heat extracted from the collector. The results agree with the findings made by other authors who have studied flat plate solar collectors.
A Study of the Performance of a Hybrid Liquid Desiccant Cooling System Using Lithium Chloride
Authors: Mago Pedro , Goswami D. Yogi
Published: January 2003

This paper presents field test of a hybrid solar liquid desiccant cooling system conducted at a test house at the University of Florida’s Energy Research and Education Park. These tests consisted of operating the air conditioning system at the test house in two configurations: the conventional vapor compression system and the hybrid desiccant system. Experiments were conducted to study the influence of the air mass flow rate, temperature of the inlet air, temperature of the desiccant, and desiccant mass flow rate on the performance of both system configurations. Based on the field test results, it was found that the hybrid desiccant system improves the air conditioning performance in the field test house by decreasing the outlet humidity and temperature of the air.
Exergy Analysis of a Combined Power and Refrigeration Thermodynamic Cycle Driven by a Solar Heat Source
Authors: Hasan Afif Akel , Goswami D. Y.
Published: January 2003

Exergy thermodynamics is employed to analyze a binary ammonia water mixture thermodynamic cycle that produces both power and refrigeration. The analysis includes exergy destruction for each component in the cycle as well as the first law and exergy efficiencies of the cycle. The optimum operating conditions are established by maximizing the cycle exergy efficiency for the case of a solar heat source. Performance of the cycle over a range of heat source temperatures of 320–460°K was investigated. It is found that increasing the heat source temperature does not necessarily produce higher exergy efficiency, as is the case for first law efficiency. The largest exergy destruction occurs in the absorber, while little exergy destruction takes place in the boiler.
An Unstructured Finite Element Solver for Ship Hydrodynamics Problems
Authors: Garcı´a J. , On˜ate E.
Published: January 2003

A stabilized semi-implicit fractional step algorithm based on the finite element method for solving ship wave problems using unstructured meshes is presented. The stabilized governing equations for the viscous incompressible fluid and the free surface are derived at a differential level via a finite calculus procedure. This allows us to obtain a stabilized numerical solution scheme. Some particular aspects of the problem solution, such as the mesh updating procedure and the transom stern treatment, are presented. Examples of the efficiency of the semi-implicit algorithm for the analysis of ship hydrodynamics problems are presented.
Mesh Moving Techniques for Fluid-Structure Interactions With Large Displacements
Authors: Stein K. , Tezduyar T. , Benney R.
Published: January 2003

In computation of fluid-structure interactions, we use mesh update methods consisting of mesh-moving and remeshing-as-needed. When the geometries are complex and the structural displacements are large, it becomes even more important that the mesh moving techniques are designed with the objective to reduce the frequency of remeshing. To that end, we present here mesh moving techniques where the motion of the nodes is governed by the equations of elasticity, with selective treatment of mesh deformation based on element sizes as well as deformation modes in terms of shape and volume changes. We also present results from application of these techniques to a set of two-dimensional test cases.
A Method for Particle Simulation
Authors: Zhang Z. , Prosperetti A.
Published: January 2003

This paper extends a recent approach to the direct numerical simulation of particle flows to the case in which the particles are not fixed. The basic idea is to use a local analytic representation valid near the particle to “transfer” the no-slip condition from the particle surface to the adjacent grid nodes. In this way the geometric complexity arising from the irregular relation between the particle boundary and the underlying mesh is avoided and fast solvers can be used. The results suggest that the computational effort increases only slowly with the number of particles so that the method is efficient for large-scale simulations. The focus here is on the two-dimensional case (cylindrical particles), but the same procedure, to be developed in forthcoming papers, applies to three dimensions (spherical particles).
Short-Term Characterization of Building Integrated Photovoltaic Panels*
Authors: Fanney A. Hunter , Dougherty Brian P. , Davis Mark W.
Published: January 2003

Building integrated photovoltaics, the integration of photovoltaic cells into one or more exterior building surfaces, represents a small but growing part of today’s $2 billion dollar photovoltaic industry. A barrier to the widespread use of building integrated photovoltaics (BIPV) is the lack of validated predictive simulation tools needed to make informed economic decisions. The National Institute of Standards and Technology (NIST) has undertaken a multi-year project to compare the measured performance of BIPV panels to the predictions of photovoltaic simulation tools. The existing simulation models require input parameters that characterize the electrical performance of BIPV panels subjected to various meteorological conditions. This paper describes the experimental apparatus and test procedures used to capture the required parameters. Results are presented for custom fabricated mono-crystalline, polycrystalline, and silicon film BIPV panels and a commercially available triple junction amorphous silicon panel.
Adaptive Optimal Control of a Grid-Independent Photovoltaic System
Authors: Henze Gregor P. , Dodier Robert H.
Published: January 2003

This paper investigates adaptive optimal control of a grid-independent photovoltaic system consisting of a collector, storage, and a load. The control algorithm is based on Q-Learning, a model-free reinforcement learning algorithm, which optimizes control performance through exploration. Q-Learning is used in a simulation study to find a policy which performs better than a conventional control strategy with respect to a cost function which places more weight on meeting a critical base load than on those non-critical loads exceeding the base load.
Influence of Heat Transfer at the Interface on the Thermocapillary Convection in the Adjacent Phase
Authors: Jiang and Y. , Floryan J. M.
Published: January 2003

Thermocapillary convection in a cavity is considered. It is shown that when the cavity is heated through its sides, reduction of heat transfer across the interface leads to an increase of the interface deformation. When the same cavity is heated through the interface, similar reduction of heat transfer across the interface results in diminished convection and reduced interface deformation.
Modal analysis of broadband acoustic receptions at 3515-km range in the North Pacific using short-time Fourier techniques
Authors: Wage Kathleen E. , Baggeroer Arthur B. , Preisig James C.
Published: January 2003

In 1995–1996 the Acoustic Thermometry of Ocean Climate (ATOC) experiment provided an opportunity to study long-range broadband transmissions over a series of months using mode-resolving vertical arrays. A 75-Hz source off the California coast transmitted broadband pulses to receiving arrays in the North Pacific, located at ranges of 3515 and 5171 km. This paper develops a short-time Fourier transform (STFT) processor for estimating the signals propagating in the lowest modes of the ocean waveguide and applies it to analyze data from the ATOC experiment. The STFT provides a convenient framework for examining processing issues associated with broadband signals. In particular, this paper discusses the required frequency resolution for mode estimation, analyzes the broadband performance of two standard modal beamforming algorithms, and explores the time/frequency tradeoffs inherent in broadband mode processing. Short-time Fourier analysis of the ATOC receptions at 3515 km reveals a complicated arrival structure in modes 1–10. This structure is characterized by frequency-selective fading and a high degree of temporal variability. At this range the first ten modes have equal average powers, and the magnitude-squared coherence between the modes is effectively zero. The coherence times of the peaks in the STFT mode estimates are on the order of 5.5 min. An analysis of mean arrival times yields modal dispersion curves and indicates that there are statistically significant shifts in travel time over 5 months of ATOC transmissions.
Evaluating the function of phonetic perceptual phenomena within speech recognition: An examination of the perception of /d/–/t/ by adult cochlear implant users
Authors: Iverson Paul
Published: January 2003

This study examined whether cochlear implant users must perceive differences along phonetic continua in the same way as do normal hearing listeners (i.e., sharp identification functions, poor within-category sensitivity, high between-category sensitivity) in order to recognize speech accurately. Adult postlingually deafened cochlear implant users, who were heterogeneous in terms of their implants and processing strategies, were tested on two phonetic perception tasks using a synthetic /dɑ/–/tɑ/ continuum (phoneme identification and discrimination) and two speech recognition tasks using natural recordings from ten talkers (open-set word recognition and forced-choice /d/–/t/ recognition). Cochlear implant users tended to have identification boundaries and sensitivity peaks at voice onset times (VOT) that were longer than found for normal-hearing individuals. Sensitivity peak locations were significantly correlated with individual differences in cochlear implant performance; individuals who had a /d/–/t/ sensitivity peak near normal-hearing peak locations were most accurate at recognizing natural recordings of words and syllables. However, speech recognition was not strongly related to identification boundary locations or to overall levels of discrimination performance. The results suggest that perceptual sensitivity affects speech recognition accuracy, but that many cochlear implant users are able to accurately recognize speech without having typical normal-hearing patterns of phonetic perception.
The sound-speed gradient and refraction in the near-ground atmosphere
Authors: Wilson D. Keith
Published: January 2003

A systematic description of sound refraction in the near-ground atmosphere is developed by modeling the effective sound-speed gradient with Monin–Obukhov similarity theory. The resulting gradient equation can be recast in a form involving just three nondimensional variables. The first is the ratio of a sound-speed scale (representing the strength of the turbulent fluctuations in the sound speed) to the friction velocity. The second is the ratio of the actual height to a transitional height where contributions from the near-ground wind-speed gradients and the adiabatic lapse rate are roughly balanced. The third is simply the cosine of the angle between the propagation direction and mean wind direction. When the magnitude of the sound-speed scale/friction velocity ratio is large, refraction is unconditionally upward or downward, depending on sign of the ratio. A small value for this ratio indicates nearly neutral atmospheric stratification, for which refraction is determined by the wind direction for small values of the nondimensional height and is upward for larger values. The contribution to refraction from air humidity is determined as a function of the Bowen ratio and found to be significant over wet surfaces. Weather conditions appropriate for measurement of sound pressure levels are also discussed.
Energy radiated by a point acoustic dipole that reverses its uniform velocity along its rectilinear path
Authors: Gaunaurd G. C. , Everstine G. C.
Published: January 2003

This work extends a mathematical approach developed recently for monopoles to describe the sound energy radiated by a rectilinearly moving dipole that changes direction along its trajectory. Although the dipole travels with constant speed, it undergoes acceleration by reversing its direction during a finite time interval along its path. This work determines the joint angular and frequency distribution of the radiated energy, its angular distribution, and the total radiated energy output. Results for the radiated energy are systematized by expressing the radiation integrals in terms of hypergeometric functions. This procedure simplifies the evaluations, particularly at low Mach numbers, and permits the comparison of results to the earlier monopole case.
Audiogram of a striped dolphin (Stenella coeruleoalba)
Authors: Kastelein Ronald A. , Hagedoorn Monique , Au Whitlow W. L. , de Haan Dick
Published: January 2003

The underwater hearing sensitivity of a striped dolphin was measured in a pool using standard psycho-acoustic techniques. The go/no-go response paradigm and up–down staircase psychometric method were used. Auditory sensitivity was measured by using 12 narrow-band frequency-modulated signals having center frequencies between 0.5 and 160 kHz. The 50% detection threshold was determined for each frequency. The resulting audiogram for this animal was U-shaped, with hearing capabilities from 0.5 to 160 kHz (8 13 oct). Maximum sensitivity (42 dB re 1 μPa) occurred at 64 kHz. The range of most sensitive hearing (defined as the frequency range with sensitivities within 10 dB of maximum sensitivity) was from 29 to 123 kHz (approximately 2 oct). The animal’s hearing became less sensitive below 32 kHz and above 120 kHz. Sensitivity decreased by about 8 dB per octave below 1 kHz and fell sharply at a rate of about 390 dB per octave above 140 kHz.