bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive Restoration in Biodiversity Hotspots: Consequences for an Atlantic Rainforest Lizard Taxocene
Authors: Guerrero Agustín Camacho , da Rocha Pedro Luís Bernardo
Published: November 2009

Long‐term conservation in biodiversity hotspots depends on the recovery of communities in secondary forest fragments. In most cases, however, recovery strategies for these areas are based only on passive restoration. It is therefore necessary to determine the efficiency of such strategies. In this study, we assess the efficiency of passive restoration on a 567‐ha 28‐yr‐old fragment of Atlantic Rainforest in Northeastern Brazil. We measured richness, composition, abundance and biomass of a lizard taxocene and also vegetation structure and availability of several microhabitat descriptors in 18 plots of this secondary forest. We then compared them with measures in 29 plots from two neighboring reference sites. Species richness, abundance, biomass and microhabitat descriptors availability inside the secondary fragment did not differ from reference sites. However, composition and vegetation structure showed small differences. Some forest specialist lizards, which should be a focus of conservation efforts in fragmented landscapes of the Atlantic Rainforest, were not found in the fragment and data indicate that this was not due to sampling or a lack of suitable habitat or microhabitat. In the presence of preserved source sites, passive restoration may be a cheap and effective way to recover lizard taxocenes of the Atlantic Rainforest. Some of the species may need to be re‐introduced to accelerate the full recovery of original composition of lizard taxocenes in secondary Atlantic Rainforests.
Annual Rainfall and Seasonality Predict Pan‐tropical Patterns of Liana Density and Basal Area
Authors: DeWalt Saara J. , Schnitzer Stefan A. , Chave Jérôme , Bongers Frans , Burnham Robyn J. , Cai Zhiquan , Chuyong Georges , Clark David B. , Ewango Corneille E. N. , Gerwing Jeffrey J. , Gortaire Esteban , Hart Terese , Ibarra‐Manríquez Guillermo , Ickes Kalan , Kenfack David , Macía Manuel J. , Makana Jean‐Remy , Martínez‐Ramos Miguel , Mascaro Joseph , Moses Sainge , Muller‐Landau Helene C. , Parren Marc P. E. , Parthasarathy Narayanaswamy , Pérez‐Salicrup Diego R. , Putz Francis E. , Romero‐Saltos Hugo , Thomas Duncan
Published: November 2009

We test the hypotheses proposed by Gentry and Schnitzer that liana density and basal area in tropical forests vary negatively with mean annual precipitation (MAP) and positively with seasonality. Previous studies correlating liana abundance with these climatic variables have produced conflicting results, warranting a new analysis of drivers of liana abundance based on a different dataset. We compiled a pan‐tropical dataset containing 28,953 lianas (≥2.5 cm diam.) from studies conducted at 13 Neotropical and 11 Paleotropical dry to wet lowland tropical forests. The ranges in MAP and dry season length (DSL) (number of months with mean rainfall <100 mm) represented by these datasets were 860–7250 mm/yr and 0–7 mo, respectively. Pan‐tropically, liana density and basal area decreased significantly with increasing annual rainfall and increased with increasing DSL, supporting the hypotheses of Gentry and Schnitzer. Our results suggest that much of the variation in liana density and basal area in the tropics can be accounted for by the relatively simple metrics of MAP and DSL.
Le coup d'œil du spectateur: Spectatorial Function and Stage Space in French Theatre Design, 1760‐1784
Authors: CAMP PANNILL
Published: November 2009

The sightlines which architects such as Oppenord and Roubo the Younger drew on their theatre plans demonstrate an attempt to align stage spaces and optical fields. Indeed, the reform‐minded architects of the period 1748 to 1784 applied geometrical forms to their plans, and adopted a terminology borrowed from optics, the science of light and vision. In focusing specifically on the theoretical texts and architectural drawings published between 1765 and 1784, we argue that this use of optical space indicates a dislocation between, on the one hand, the spatial representation which the French reformers promoted in their drawings and, on the other, stage perspective, which had, since the previous century, been associated with the influence of the Italian Baroque. In the 1780s, architects gradually abandoned the use of stage perspective, preferring instead a theatrical space modelled after an ostensibly natural optical encounter.
De la police des spectacles à la civilisation des mœurs théâtrales: domestication du public et production des affects chez Louis‐Sébastien Mercier
Authors: POIRSON MARTIAL
Published: November 2009

Louis‐Sébastien Mercier's conception of theatre revolves around the audience. He writes extensively about its social composition, its patterns of attendance and, in particular, the attitudes of parterre spectators. If Mercier goes furthest in acknowledging the audience, particularly the popular audience, as the ultimate judge of a performance, it is also he who betrays most explicitly the contradictions in his aesthetic and ideological stance. He places remarkable faith in the judgement of the people, arguing that the playwright should be subservient to a popular audience and that access to the theatre be made more democratic. He wants to see parterre audiences seated, for they alone are capable of judging the quality of the plays they see. He never misses a chance to taunt actors for their arrogance or authors for their pretensions. He believes in the educational value of a theatre that can inculcate civic and patriotic pride and can teach a popular audience its political responsibilities. And he pleads for the relaxation of police controls on playhouses as the only way to allow for the unhindered development of a more civil theatre culture. At the same time, however, he acknowledges that the creation of a ‘popular theatre’ is not easy, and is well aware of both the risks of manipulating or over‐controlling the audience and the dangerous potential inherent in exploiting theatricality to modify public opinion.
Copistes et secrétaires‐souffleurs à la Comédie‐Française au dix‐huitième siècle, de Saint‐Georges à Delaporte
Authors: RAZGONNIKOFF JACQUELINE
Published: November 2009

The numerous eighteenth‐century promptbooks conserved in the Bibliothèque‐Musée de la Comédie‐Française are for the most part in the hand of copyists attached to the company, people whose duties, often closely associated with those of prompters, gradually evolved over the course of the century. Traces of these people, who were as vital to the company as a whole as they were to individual actors who came to place great trust in them, may be discovered, scattered, not only throughout the minutes of company meetings and registers, but also in bills for copying work and other minor expenses incurred by the secretariat of the troupe. By collating these various sources it is possible to put a face to several of these figures, to identify the manuscripts and documents they copied out, the payment they received, and to understand exactly what their duties entailed over the course of the century. In addition, we shall consider the ‘outside’ copyists who were occasionally called upon, and those of the company's music copyists of whom we have evidence. After all, music in one form or another was an essential element of all eighteenth‐century performances.
Rousseau and Favart at Fontainebleau, Pergolesi at Versailles
Authors: CHARLTON DAVID
Published: November 2009

The French court, far from being caught off guard by the arrival of the Bouffons in 1752, had in fact been pursuing an independent policy which favoured the performance of operas since 1745. In 1749, it was its taste for spectacle that prompted the court to purchase buildings at Fontainebleau which would make it possible to house the staffs of the Royal Entertainments Department (les Menus‐Plaisirs), the workshops and stage properties departments, and to install a small rehearsal room. Three years later, Louis Bays de Cury, who was in overall charge of the Royal Entertainments Department, seized the opportunity of putting on Rousseau's Le devin du village. Two documents preserved in the French National Archives (O1 2991 and O1 2992) reveal the details not only of the extraordinary expenses incurred in the journeys to Fontainebleau, but also the particularly mixed styles of programming. They also give details of the costumes made for Le devin and other performances, which in some instances enhance our understanding of the stage practice of the Italian actors. In 1752, the passion for opera spread from Fontainebleau to Versailles, where the stage of the Salle de Comédie, located in the south wing of the palace, was subsequently enlarged in order to house not only the Bouffons, but also to permit the staging of Zélindor, roi des Silphes, a ballet by Moncrif, Rebel and Francœur. Zélindor was also staged at Versailles in 1745, but that was on a stage erected in the Grande Ecurie, which was destroyed by fire in 1751.
HYPERTENSION MANAGEMENT: LIFESTYLE INTERVENTIONS IN A TRANSCULTURAL CONTEXT
Authors: Ho Tai Mooi
Published: November 2009

Hypertension is a risk factor for cardiovascular and kidney diseases. According to estimation, the prevalence of hypertension will increase unless extensive and effective preventive measures are implemented. The diversity of languages and cultures of the hypertensive patients requiring adequate blood pressure control make communications difficult in many instances.

Nursing intervention for patients to adopt a healthy lifestyle requires effective communication. But the communication problems encountered in a culturally diverse context can result in undesirable outcomes for the patients and the health‐care team. This paper describes the production of a document to assist staff address the difficulty in intercultural communication, which could be used anywhere in the world. This document can facilitate nursing intervention to achieve optimal hypertension management in a transcultural context, responding to the challenge regarding preventive measures to halt increase in hypertension prevalence.
THE AUSTRALIAN AND NEW ZEALAND DIALYSIS WORKFORCE STUDY IN THE INTERNATIONAL CONTEXT
Authors: Polaschek Nick , Bennett Paul N. , McNeill Liz
Published: November 2009

Background: Given increasing demand for renal replacement therapy, this study sought to identify of key workforce issues facing dialysis units, based on a “snapshot” of the current workforce.

Methods: A web‐based survey of all dialysis unit managers in Australia and New Zealand, in October 2008, about their workforce.

Results: A significant minority of dialysis staff in most regions were not registered nurses. Many renal registered nurses worked part‐time. Staff/patient ratios in dialysis units varied significantly by region, reflecting the relative prevalence of home therapies. Most dialysis units were generally adequately staffed. The proportion of registered nurses with specific renal qualifications varied significantly by region.

Conclusion: The changing character of the workforce in the dialysis unit in the future will require clarification of the relationships between different categories of dialysis staff. Specialty education for nurses needs to be oriented to equipping staff to be effective in their changing work environment.
USE OF GADOLINIUM FOR CAROTID ARTERY ANGIOGRAPHY AND STENTING IN PATIENTS WITH RENAL INSUFFICIENCY
Authors: Yaganti Vamsee , Alani Firas , Yaganti Sushmita , Goldberg Sheldon , McCormick Daniel
Published: November 2009

Use of iodinated contrast media (ICM) for angiography can result in contrast‐induced nephropathy (CIN). Gadolinium‐based contrast media (GCM) have been used in angiography with a goal to reduce the incidence of CIN. We performed a retrospective analysis involving 85 patients with renal insufficiency who underwent 97 carotid artery angiography and stenting (CAAS) procedures with a combination of GCM and ICM. The incidence of peri‐procedural death, Q wave myocardial infarction (QWMI), stroke and CIN were recorded. Patients in GCM group had worse preprocedure renal function compared to ICM group. There were no peri‐procedural deaths or QWMI in both groups. The incidence of stroke was 2.2% in GCM group and 0% in ICM group. The incidence of CIN were similar in GCM and ICM groups (8.5% vs. 10%, respectively, p NS). However, the predicted risk of CIN was 18.5% for GCM group and 10.4% for ICM group. Use of GCM and ICM combination for CAAS resulted in a 50% reduction in the incidence of predicted CIN risk compared to ICM.
Spinal adenosine A2Areceptor inhibition enhances phrenic long term facilitation following acute intermittent hypoxia
Authors: Hoffman M. S. , Golder F. J. , Mahamed S. , Mitchell G. S.
Published: November 2009

Phrenic long term facilitation (pLTF) is a form of respiratory plasticity induced by acute intermittent hypoxia. pLTF requires spinal serotonin receptor activation, new BDNF synthesis and TrkB receptor activation. Spinal adenosine 2A (A2A) receptor activation also elicits phrenic motor facilitation, but by a distinct mechanism involving new TrkB synthesis. Because extracellular adenosine increases during hypoxia, we hypothesized that A2Areceptor activation contributes to acute intermittent hypoxia (AIH)‐induced pLTF. A selective A2Areceptor antagonist (MSX‐3, 8 μg kg−1, 12 μl) was administered intrathecally (C4) to anaesthetized, vagotomized and ventilated male Sprague–Dawley rats before AIH (three 5 min episodes, 11% O2). Contrary to our hypothesis, pLTF was greater in MSX‐3versusvehicle (aCSF) treated rats (97 ± 6%vs.49 ± 4% at 60 min post‐AIH, respectively;P< 0.05). MSX‐3 and aCSF treated rats did not exhibit facilitation without AIH (time controls; 7 ± 5% and 9 ± 9%, respectively;P> 0.05). A second A2Areceptor antagonist (ZM2412385, 7 μg kg−1, 7 μl) enhanced pLTF (85 ± 11%,P< 0.05), but an adenosine A1receptor antagonist (DPCPX, 3 μg kg−1, 10 μl) had no effect (51%± 8%,P> 0.05), indicating specific A2Areceptor effects. Intrathecal methysergide (306 μg kg−1, 15μl) blocked AIH‐induced pLTF in both MSX‐3 and aCSF treated rats, confirming that enhanced pLTF is serotonin dependent. Intravenous MSX‐3 (140 μg kg−1, 1 ml) enhanced both phrenic (104 ± 7%vs.57 ± 5%,P< 0.05) and hypoglossal LTF (46 ± 13%vs.28 ± 10%;P< 0.05). In conclusion, A2Areceptors constrain the expression of serotonin‐dependent phrenic and hypoglossal LTF following AIH. A2Areceptor antagonists (such as caffeine) may exert beneficial therapeutic effects by enhancing the capacity for AIH‐induced respiratory plasticity.
Position Tracking Control of a Miniature Water Hydraulic Rotary Actuator
Authors: Sindrey Russell , Bone Gary M.
Published: November 2009

Over the past 20 years, research in the field of miniature actuators has increased substantially due to advances in smart material fabrication, semiconductor chip technology, and computer processing capability. Hydraulic cylinders offer many potential benefits as miniature actuators, including high power-to-weight ratio, mechanical stiffness, smooth motion, and the potential for high positional accuracy. Despite their benefits, the control of hydraulic cylinders with bore diameters under 10 mm has not been previously studied. The most significant obstacle to implementing the use of miniature cylinders is the unavailability of off-the-shelf proportional valves that are compatible with hydraulic fluid and precise enough for the position control task. In this paper, two novel model-based nonlinear control strategies are presented for the position control of a rotary actuator powered by two 4 mm bore diameter cylinders. Four off-the-shelf, low cost, 2/2 on/off miniature solenoid valves were used to control the flow of water to and from the cylinder chambers. A novel valve coordination scheme is also presented that allows the on/off valves to approximate the behavior of a proportional valve. The tracking performance of each controller was experimentally tested and both controllers were found to achieve steady-state positioning accuracies of the cylinders within ±0.07 mm. The robustness of the controllers to changes in payload mass and vertical orientation was also tested. Results from several experiments are presented and compared.
Application of an Epoxy Cap in a Flip-Chip Package Design
Authors: Suhir E.
Published: November 2009

In order to combine the merits of epoxies, which provide good environmental and mechanical protection, and the merits of silicone gels, resulting in low stresses, one can use an encapsulation version, where a low modulus gel is utilized as a major encapsulant, while epoxy is applied as a protecting cap. Such an encapsulation version is currently under consideration, parallel with a metal cap version, for the Advanced VLSI package design which is being developed at AT&T Bell Laboratories. We recommend that the coefficient of thermal expansion for the epoxy be somewhat smaller than the coefficient of thermal expansion for the supporting frame. In this case the thermally induced displacements would result in a desirable tightness in the cap/frame interface. This paper is aimed at the assessment of stresses, which could arise in the supporting frame and in the epoxy cap at low temperatures. Also, the elastic stability of the cap, subjected to compression, is evaluated. The calculations were executed for the Advanced VLSI package design and for a Solder Test Vehicle (STV), which is currently used to obtain preliminary information regarding the performance of the candidate encapsulants. It is concluded that in order to avoid buckling of the cap, the latter should not be thinner than 15 mils (0.40 mm) in the case of VLSI package design and than 17.5 mils (0.45 mm) in the case of STV. At the same time, the thickness of the cap should not be greater than necessary, both for smaller stresses in the cap and for sufficient undercap space, required for wirebond encapsulation. The obtained formulas enable one to evaluate the actual and the buckling stresses. Preliminary test data, obtained by using STV samples, confirmed the feasibility of the application of an epoxy cap in a flip-chip package design.
The Effect of Variations in Stream-Wise Spacing and Length on Convection From Surface Mounted Rectangular Components
Authors: Lehmann G. L. , Wirtz R. A.
Published: November 2009

The effect of variations in stream-wise spacing and component length on convection from rectangular, surface mounted components in a channel flow are reported. Component dimensions are the same order of magnitude as the channel wall-to-wall spacing. The channel Reynolds number, with air as the coolant, ranged from 670 to 3000. Flow visualization showed that under the above conditions the channel flow is transitional. The effect of variations in component stream-wise spacing on the level of turbulence in the channel and on the interaction between the core of the channel flow and the recirculating flow in cavities between components is discussed. Pressure drop measurements show that the dominant loss mechanism is due to form drag caused by the components. Local heat transfer measurements are made using an interferometer. Analysis of the results shows that the overall heat transfer is properly correlated in terms of a flow Reynolds number based on the component length. At small component Reynolds number, the overall conductance tends towards the laminar smooth wall value. An overall correlation is proposed which includes the effect of component Reynolds number, channel wall-to-wall spacing, and component stream-wise spacing.
An Experimental Study of Natural Convection Cooling of an Array of Heated Protrusions in a Vertical Channel in Water
Authors: Joshi Y. , Willson T. , Hazard S. J.
Published: November 2009

An experimental investigation of steady state and transient natural convection from a column of eight in-line rectangular heated protrusions in a vertical channel in water is presented. Flow visualizations and element surface temperature measurements were carried out for several power dissipation levels in the range of 0.2–1.5 W per component and channel spacings from 6.4 to 23 mm. The three-dimensional steady flows were visualized in two mutually perpendicular planes. Average component temperatures determined from the measurements on the five fluid exposed faces were used to obtain nondimensional heat transfer rates. Heat transfer data for all channel spacings except the smallest did not differ from the measurements for an isolated surface by more than 14 percent. For the smallest spacing, the component surface temperatures increased significantly due to a reduction in the fluid velocities. Measurements and flow visualizations during the transient indicated an initial diffusive transport period, followed by the evolution of convective effects. No overshoots in component temperatures were found. Steady transport responses with selectively powered components are also examined.
Sensible Heating and Boiling Incipience in Free-Falling Dielectric Liquid Films
Authors: Marsh William J. , Mudawar Issam
Published: November 2009

Controlling boiling incipience is of paramount importance for reliable operation of liquid-cooled microelectronic heat sources during power transients. This study focuses on heat transfer from a simulated multichip module to a falling film. Experiments have been performed to develop an understanding of the influence of surface tension and wetting characteristics on sensible heat transfer and boiling incipience in free-falling dielectric (FC-72) liquid films. The boiling results reveal that the vanishingly small contact angle of FC-72 precludes the application of correlations currently employed to predict incipience. Also, the temperature excursion commonly encountered upon boiling incipience in wetting fluids was nonexistent in all the experimental runs.
An Experimental Study of Natural Convection From an Array of Heated Protrusions on a Vertical Surface in Water
Authors: Joshi Y. , Willson T. , Hazard S. J.
Published: November 2009

An experimental study of steady state and transient natural convection from a single column of eight heated, rectangular protrusions mounted on a vertical surface in water is presented. The component power dissipation levels were varied in the range 0.2–1.5 W using foil heaters attached to the base of each protrusion. Visualizations in three different vertical planes indicated a three-dimensional, laminar developing boundary region type flow structure away from the protrusions. Near the vertical surface, the fluid followed the protrusion boundaries with no evidence of vortex formation. Surface temperatures were measured at the centers of each of the five fluid exposed faces. Nondimensional heat transfer rates were calculated based on these measurements. Accounting for the increasing convected energy downstream resulted in a single correlation for all components and power levels. Temperature measurements in the adjacent fluid were made using a movable hypodermic probe. Transport evolution during the transient showed initially diffusive patterns, followed by rapid development of entrainment.
Component Placement for Reliability on Conductively Cooled Printed Wiring Boards
Authors: Osterman M. D. , Pecht M.
Published: November 2009

With the increased demand for highly reliable electronic equipment and limitations that make improvements to the reliability of individual components difficult to obtain, methods to improve the reliability at higher levels of packaging are being sought. This article presents the mathematical theory for improving reliability by appropriately locating components on conductively cooled printed wiring boards based on the thermal behavior of the components on the board. Placement techniques are then constructed to minimize the total failure rate of the collection of components.
Analytical Modeling in Electronic Packaging Structures: Its Merits, Shortcomings and Interaction With Experimental and Numerical Techniques
Authors: Suhir E.
Published: November 2009

We discuss the role of theoretical and, in particular, analytical modeling in mechanical problems for electronic packaging, including requirements for a feasible theoretical model, how such a model is developed, the role of mathematics, what can be gained by using theoretical modeling, as well as the interaction of analytical, numerical (computer-aided) and experimental models. Peculiarities of theoretical modeling in Structural Analysis are also briefly discussed.
Strain-Life Behavior in 60/40 Solder
Authors: Solomon H. D.
Published: November 2009

This paper describes low cycle fatigue test run at −50°C, 35°C, 125°C, and 150°C on thin 60 Sn/40 Pb solder joints, tested in simple shear. The low cycle fatigue behavior was found to be a function of the criteria used to define the fatigue life. Different drops in the hysteresis load, measured when a constant plastic strain is being applied, was used to define failure. Not only was the magnitude of the fatigue life a function of the load drop definition for failure, it was also found that the Coffin-Manson low cycle fatigue exponent was a function of this definition. The choice of dependent variable for the curve fitting procedure used to calculate the Coffin-Manson exponent is also considered.
Mechanical Analysis for Thermal Grease Enhanced Modules Enclosing a Silicon Chip
Authors: Engel P. A. , Strope D. H. , Wray T. E.
Published: November 2009

In metallized ceramic technology substantial mechanical stresses arise in assembly, insertion and cyclic thermal loading of thermally enhanced modules. This paper describes some experimental and analytical investigations performed for safeguarding the structural integrity of modules in which heat conduction from the chip to the module cap was enhanced by a “thermal grease” compound.
Lifetime Prediction of Solder Materials
Authors: Zubelewicz A. , Berriche R. , Keer L. M. , Fine M. E.
Published: November 2009

Fatigue lifetimes of lead-low tin solders have been investigated. Results indicate that the Coffin-Manson law does not necessarily fit experimental data. The phenomenon can be correlated with a change in the failure mode as follows: transgranular and mixed for higher strain ranges, and intergranular at lower strains. The present modeling incorporates these micromechanical features, and in addition shows that the variation in the failure mode and in the magnitude of the stresses from varying strain range (during the cyclic process) coincide with each other.
An Analysis of Shrinkage Porosity in Aluminum Ball Bonding Process
Authors: Huang L. J. , Ramakrishna K. , Ayyaswamy P. S. , Cohen I. M.
Published: November 2009

The thermal evolution of liquid and solid during the radially inward solidification of spherical balls of liquid has been studied by accounting for the increase in the density as phase transition occurs from liquid to solid. With this increase in density, the system geometry becomes that of a hollow sphere with a void at the center. We consider pure metals and binary alloys. For alloy solidification, the void begins to grow only after the outer surface reaches the solidus temperature. The temperature dependence of the thermophysical properties of the two phases is taken into account along with the natural convective and radiative loss to the ambient. The model has been applied to pure aluminum, Al – 1% Si, Al - 1% Mg, and Al - 2% Mg for a range of initial radii of the balls. From this study, we conclude that: (a) the volume fraction of the shrinkage void in the ball is independent of the initial radius for pure metal while it increases monotonically with initial radius for the binary alloys, and (b) for identical conditions, the voids are much smaller in alloys than in the pure metal.
Prediction of Temperature Distributions and Thermal Expansions Within a Fixed Disk-Drive Storage System
Authors: Eibeck P. A. , Clauss N. S. , Cohen D. J.
Published: November 2009

The increase in the track densities of disk drive systems has caused the sensitivity of the read/write head alignment to thermal expansions to be a primary design concern. A simple thermal model for predicting the transient temperature distributions and resulting thermal expansions within a disk drive has been developed to evaluate the feasibility of utilizing a thermal prediction code in the design process. Experimental measurements of the temperatures within an actual disk drive, including the radial temperature profile on the rotating disks, were made to compare with the model’s predictions. The air temperature in the gaps between corotating disks is nearly 10 percent warmer than air elsewhere within the disk-drive, and there is less than a 2 percent radial temperature variation along the disks. The steady-state temperatures within a disk-drive are very sensitive to slight changes in external heat transfer coefficient under free convection cooling. Thermal expansion predictions imply that thermal gradients along the hub caused by heat sources in the base and axial change in the arm position between neighboring disks are the major contributions to off-track errors.
Approximating the Steiner Tree in the Placement Process
Authors: Wong Yeun Tsun , Pecht Michael
Published: November 2009

By simulating the movement of a node in a tree, an iso-distance error graph (IDEG) which contains connection errors generated by replacing a Steiner tree with its equivalent non-Steiner tree is developed. The IDEG is used to estimate how well various types of non-Steiner trees function as a Steiner tree in the placement of components on a printed wiring board (PWB). To reduce connection errors in the IDEG and pursue computational efficiency, a row-based tree family in which the tree length is primarily dependent on the terminal coordinates of each row, is constructed. Then, based on the analysis of the error distribution on the IDEG, the row-based trees and the spanning tree are compared in terms of their approximation to the Steiner tree.
A Stress Singularity Parameter Approach for Evaluating the Interfacial Reliability of Plastic Encapsulated LSI Devices
Authors: Hattori T. , Sakata S. , Murakami G.
Published: November 2009

Since the stress and displacement fields near a bonding edge show singularity behaviors, the adhesive strength evaluation method, using maximum stresses calculated by a numerical stress analysis such as the finite element method, is generally not valid. In this paper, a new method, which uses two stress singularity parameters, is presented for evaluating adhesive strength. This method is applied to several kinds of molded models, composed of epoxy base resin and Fe-Ni alloy sheets, and plastic encapsulated LSI models. Predictions about the initiation and extension of delamination are compared with the results of observations made by scanning acoustic tomography on these models.
Finite Element Modeling for Optimizing Hermetic Package Reliability
Authors: Lau J. H. , Lian-Mueller L. B.
Published: November 2009

The thermal stresses in microwave packages are studied by the finite element method. Emphasis is placed on the effects of material construction and design on the reliability of very small hermetic packages. Three different microwave packages have been designed and six finite element models (two for each design) have been analyzed. To verify the validity of the finite element results, some leak tests have been performed and the results agree with the analytical conclusions. The results presented herein should provide a better understanding of the thermal behavior of hermetic packages and should be useful for their optimal design.
Conjugate Heat Transfer From a Vertical Plate With Discrete Heat Sources Under Natural Convection
Authors: Lee S. , Yovanovich M. M.
Published: November 2009

A quasi-analytical conjugate heat transfer model is developed for a two dimensional vertical flat plate with discrete heat sources of arbitrary size and power level under natural convection. The plate is located in an extensive, quiescent fluid which is maintained at uniform temperature. The model consists of an approximate analytical boundary layer solution and a one dimensional numerical conduction analysis in which an allowance is made to account for radiation heat transfer. These fluid and solid solutions are coupled through an iterative procedure. A conjugate problem is solved when a converged temperature distribution is obtained at the plate-fluid interface, concurrently satisfying the thermal fields on both sides of the interface. Comparisons of the surface temperature variations obtained by using the present model are made with existing numerical and experimental data which were obtained for cases with two strip heat sources mounted flush with the surface of a vertical plate in air. The model is shown to be in good agreement. In addition, the convection and radiation heat flux variations are presented. The results illustrate the importance of radiation heat transfer for estimating surface temperatures of the plate.
The Cavity Width Effect on Immersion Cooling of Discrete Flush-Heaters on One Vertical Wall of an Enclosure Cooled from the Top
Authors: Carmona R. , Keyhani M.
Published: November 2009

The width effect on natural convection heat transfer due to discrete flush-heated sections of equal height in an enclosure cooled from the top is experimentally investigated. Five heated sections are uniformly distributed along a vertical side wall, where the height of the unheated sections is equal to that of the heated sections. All other vertical surfaces and the bottom plate are insulated. The experiments are conducted for six values of cavity width resulting in a variation in the cavity height-to-width ratio (aspect ratio) of 3.67 to 12.22. Ethylene glycol and FC-75 (a dielectric fluid) are used as the convective media. The flow visualization results with ethylene glycol reveal a fairly inactive core flow at low power inputs and small cavity width. Higher values of the power input and cavity width transforms a rather well structured core flow into a time dependent one with higher horizontal velocities toward the “hot” wall. For a given cavity width, it is found that the heat transfer results for all the heated sections can be unified and presented by a single correlation through use of a local height as the length scale. The local height of a given heated section is measured from the bottom of the cavity to the mid-height of that section. Based on the local height length scale the data for all the cavity widths are correlated and an explicit relation for the aspect ratio effect on local Nusselt number is reported. The data indicate that an increase in the cavity width results in an increase in the heat transfer coefficients of the heated sections. A comparison between ethylene glycol and FC-75 revealed no appreciable Prandtl number effect, which is in agreement with a previously reported prediction. A heat transfer coefficient for the top surface is defined based on the total convective heat flux at this surface and an average temperature difference between the heated sections and the top plate. The results show that for a given heat flux at the top, the highest heat transfer coefficient on this surface is obtained with the lowest cavity width.
Thermal Stress Analysis of a Bimaterial Strip Subject to an Axial Temperature Gradient
Authors: Eischen J. W. , Everett J. S.
Published: November 2009

Formulas are derived for the stresses and displacements in a bimaterial strip which is subjected to a temperature gradient that varies linearly in the longitudinal direction. The solution is obtained by superposing certain fundamental linear elastic stress states which are compatible with bar and beam theory. The analytical results are approximate in the sense that stress-free boundary conditions are not satisfied exactly, since only zero resultant force and moment conditions are enforced. Finite element calculations have been performed to verify the results and to ascertain the level of stress concentration near the ends of the strip.
Influence of Mach Number and End Wall Cooling on Secondary Flows in a Straight Nozzle Cascade
Authors: Sieverding C. H. , Wilputte Ph.
Published: November 2009

This paper describes the results of an experimental study of the effect of Mach number and end wall cooling on the secondary flow in a straight nozzle cascade with an aspect ratio of h/c = 0.83. The tests were performed for the outlet Mach numbers M2 = 0.1, 0.6 and 0.8. The cooling tests are done for one specific cooling configuration consisting of three double rows of injection holes positioned at the leading edge, inside the blade passage and in the throat. The flow was injected into the direction of the free stream direction. The tests are carried out for two cooling mass flow ratios: m˙/m˙tot = 0.02 and 0.045. The corresponding injection to main flow pressure ratios are: 1.0, 1.16 for M2 = 0.6 and 1.0, 1.26 for M2 = 0.8. The flow surveys are made with three-directional pressure probes.
Rotordynamic Instability in Centrifugal Compressors—Are All the Excitations Understood?
Authors: Vance J. M. , Laudadio F. J.
Published: November 2009

A published history of rotordynamic instability problems with centrifugal compressors is documented from the literature. Established theory for computerized stability analysis is reviewed, and the use of cross-coupled stiffness and damping coefficients to represent destabilizing forces is explained. A derivation of cross-coupled stiffness coefficients for torquewhirl is presented. Experimental measurements made on a simple test rig with a radial-vaned impeller are described, which show that a working fluid can exert destabilizing forces on such an impeller. These forces must be considered, in addition to journal bearing and internal hysteresis excitations, if accurate predictions of rotordynamic instability thresholds are to be made. Several classifications of these forces are hypothesized.
Advances in Labyrinth Seal Aeroelastic Instability Prediction and Prevention
Authors: Abbott D. R.
Published: November 2009

Fatigue cracking of an aircraft engine labyrinth seal occurred during pre-flight factory testing. Testing in a static rig revealed that the seal could be aeroelastically excited by the labyrinth leakage air flow. An earlier analytical model used for stability analysis was extended to account for the effect of acoustic natural frequency on the aeroelastic stability. The new model predicted that the ratio of acoustic and mechanical natural frequencies was of vital importance in determining if the nature of the pressure fluctuations within the labyrinth seal teeth provided either positive or negative aerodynamic damping to the seal. The analytical results were verified by further rig testing and also by correlation with test results for several other seals tested as part of a labyrinth seal technology program. A mechanical friction damper sleeve was designed to suppress the aeroelastic instability. The damper sleeve was tested in a rotating rig to evaluate its damping characteristics. The aircraft engine was qualified with the newly designed damper which has demonstrated its effectiveness for eight years of service and half a million hours of operation without incident.
Blade Excitation by Elliptical Whirling in Viscous-Damped Jet Engines
Authors: Klompas N.
Published: November 2009

An extension of the author’s earlier method of analyzing multi-shaft jet engine dynamics accounting for flexibility of bladed disks is outlined to calculate the first whirl harmonic for given nonlinear characteristics of squeeze-film dampers. A second whirl harmonic, of which experimental verification is found in Campbell’s paper of 1924, is shown induced by orbit ellipticity. The possibility that this harmonic, especially due to backward whirling, may be a source of blade excitation at higher frequencies than currently recognized from linear analysis is discussed by relating some engine experience.
Averaging Methods for Determining the Performance of Large Fans from Field Measurements
Authors: Gerhart P. M.
Published: November 2009

When testing large fans in the field, it is often necessary to make measurements at locations where the distributions of gas velocity, pressure, and temperature are highly irregular. When this occurs the fan pressure rise or fan specific energy is usually expressed in terms of average values of pressure, density, and temperature. This paper proposes criteria for the definition of such averages and develops defining equations for them. The averages proposed allow the continuity, energy, and ideal gas state equations to be written in simple one-dimensional form without correction factors. Performance variables such as total pressure are defined in the customary way from the averages of the fundamental flow properties.
Utility Operations: An Effective and Economic Approach to Operator Training
Authors: Studley B. C.
Published: November 2009

There is no question that, with the increasing costs of Fossil-Fuels, overall production of electricity, and replacement energy costs, the need to develop an operator’s complete familiarity with the specific plant he will be required to operate is a necessity. The major benefit is that of reduced operator errors which maximizes unit availability as dictated to by the operating staff. The approach presented utilizes the concept of developing an operator’s understanding of each system within the plant through the use of a visual tool called an operational schematic. Coupled with the use of condensed word instructions to explain both normal and abnormal operator actions in addition to a system’s control logic, the operator experiences an environment very similar to his working atmosphere. Finally, the effectiveness of this approach, considering that classroom training is coupled with continual control room and in-plant inspections, can be seen to be competitive with that obtainable from the use of a simulator but for a fraction of the cost.
Vibration in Nuclear Heat Exchangers Due to Liquid and Two-Phase Flow
Authors: Heilker W. J. , Vincent R. Q.
Published: November 2009

In order to optimize a steam generator tube bundle support system, it is necessary to understand the differences in vibration behavior of tube arrays subjected to a two-phase flow regime as compared to a single phase flow regime. The relationships discussed in this paper are based on findings derived from a comprehensive vibration testing program which included both water and simulated two-phase (air-water) flow regimes. Tube bundles of various configurations and spacings were tested in crossflow using 3/4 in. (1.9 cm) and 7/8 in. (2.2 cm) o.d. tubes with 36 in. (91 cm) span lengths and as many as 40 tubes per array. Sufficient test loop capacity was provided to drive most test array configurations up to and beyond fluid-elastic instability. Parameters obtained included displacement, effective force coefficients, damping coefficients, Strouhal numbers, and instability constants for various tube array configurations in both liquid and simulated two-phase flow mediums.
Measurements of the Mean Flow Velocity and Velocity Fluctuations at the Exit of an FC Centrifugal Fan Rotor
Authors: Raj D. , Swim W. B.
Published: November 2009

The flow from a small forward curved fan rotor was studied to provide guidance for fan design. The single width fan had a 0.23 m rotor containing 48 blades. It is typical of the centrifugal fans used in small air-conditioning units. Visualization techniques and hot wire measurements showed the rotor flow to be highly turbulent and strongly three-dimensional. The inlet flow was found to fill only 3/4 of the blade span. The shroud end of the rotor was an inactive or separated region. A jet-wake pattern occurred at the blade exit in the active flow region. The inlet flow separated at the leading edge of the blade suction surface. Design changes are offered to improve the performance of FC fans.
Measurement of Turbine Rotor Blade Flows
Authors: Dring R. P. , Joslyn H. D.
Published: November 2009

Measurement methods for obtaining various types of experimental data on a turbine rotor blade are discussed in this paper. A variety of different types of measurements have been taken in the rotating frame of reference, including: airfoil surface static pressure distributions, the radial distribution of total pressure in the incident flow, flow visualization of surface streamlines, and radial-circumferential traversing of a pneumatic probe aft of the rotor. Typical results are presented/showing interesting flow phenomena present on the rotor. In particular, results are shown which demonstrate the various viscous and inviscid mechanisms that give rise to strong radial flows.
Experimental Analysis Methods for Unsteady Flows in Turbomachines
Authors: Larguier R.
Published: November 2009

This paper describes the measuring methods developed at the ONERA Aerodynamics Department for the characterization of unsteady flows in turbomachines. They mainly concern the flow in the rotor, its wake, and boundary layers on stator or rotor blades. The means used consist of: • measurements using pressure probes or short response time pressure transducers, • measurements with hot wire probes or hot film gauges, and • direct, measurements using laser velocimeter.
Laser Anemometer Measurements in a Transonic Axial Flow Compressor Rotor
Authors: Strazisar A. J. , Powell J. A.
Published: November 2009

A laser anemometer system employing an efficient data acquisition technique has been used to make measurements upstream, within, and downstream of the compressor rotor. A fluorescent dye technique allowed measurements within endwall boundary layers. Adjustable laser beam orientation minimized shadowed regions and enabled radial velocity measurements outside of the blade row. The flow phenomena investigated include flow variations from passage to passage, the rotor shock system, three-dimensional flows in the blade wake, and the development of the outer endwall boundary layer. Laser anemometer measurements are compared to a numerical solution of the streamfunction equations and to measurements made with conventional instrumentation.
Temperature and Pressure Measurement Techniques for an Advanced Turbine Test Facility
Authors: Pollack F. G. , Cochran R. P.
Published: November 2009

A high pressure (4 × 106 N/m2), high-temperature (2400 K) turbine test facility is being constructed at the NASA Lewis Research Center for use in turbine cooling research. Several recently developed temperature and pressure measuring techniques will be used in this facility. This paper will briefly describe these measurement techniques, their status, previous applications and some results. Noncontact surface temperature measurements will be made by optical methods. Radiation pyrometry principles combined with photoelectric scanning will be used for rotating components and infrared photography for stationary components. Contact (direct) temperature and pressure measurements on rotating components will be handled with an 80-channel rotary data package which mounts on and rotates with the turbine shaft at speeds up to 17,500 rpm. The data channels are time-division multiplexed and converted to digital words in the data package. A rotary transformer couples power and digital data to and from the shaft.
The Design, Development and Operation of Gas Turbine Radio Telemetry Systems
Authors: Worthy J. G. B.
Published: November 2009

Measurements made on the rotating components of aero-gas turbines are among the most difficult of instrumentation problems. Success brings considerable reward, however, by providing a means of verifying design predictions and investigating unforeseen phenomena. This paper describes the Rolls-Royce approach to this problem and the principles used in the design of over 30 radio telemetry systems designed and manufactured within the company. A summary of operating experience reviews the problems encountered and measures taken to overcome them. The paper concludes with an impression of future requirements which are receiving attention.