bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy Exchange in Isometric Contraction of Vascular Smooth Muscle Induced by K‐ions
Authors: Beviz Andras , Lundholm Lennart , Mohme‐Lundholm Ella
Published: December 2008

Acta physiol scand. 1969. 00. 000–000. – On isometric contraction of isolated mesenteric arteries induced by K‐ions in anaerobic, glucose‐free suspension solution the increase in tension after 1 min was accompanied by a significant decrease in the content of adenosine triphosphate (0.21 ± 0.07 μmoles/g), creatine phosphate (0.30 ± 0–08 μmoles/g) and an increased lactate content (0.25 ±0.10 μmoles/g) of the vascular muscle. In the presence of 0.5 % glucose, essentially the same effect was observed on the contents of energy‐rich phosphate esters, while the effect on the lactate content varied. Three min after the addition of K+ someresynthesis of energy‐rich phosphate compounds had taken place, but the synthesis was relatively slow. The series elastic component was relatively large in mesenteric arteries. Therefore even on isometric contraction the muscle performed work on stretching of this component. After correction of this “internal” work the LP ratio L.P/H was calculated to be 4.8, i. e. about 1/2 of that demonstrated by Hill (1958) in thermoelectrical determinations in isometrically contracted skeletal muscle from the frog. In glucose‐free solution a significant correlation was found between the tension developed and the content of energy‐rich phosphate compounds in muscle.
Release of Histamine and Formation of Smooth‐Muscle Stimulating Principles in Guinea‐Pig Lung Tissue Induced by Antigen and Bee Venom Phosphatidase A
Authors: Fredholm Bo , Strandberg Kjell
Published: December 2008

Release of histamine and formation of smooth‐muscle stimulating principles (spasmogenic lipids) occurred when minced guinea‐pig lung tissue was exposed to antigen or to bee venom phosphatidase A. In agreement with earlier reports the anaphylactic histamine release was a rapid process, and it could be inhibited by anoxia in the absence of glucose, and by potassium cyanide, ninhydrin and A’‐ethyl‐maleimide. The histamine release induced by phosphatidase A was not influenced by these inhibitors or by anoxia, and the release was slower than in anaphylaxis. The spasmogenic lipids formed had similar chromatographic and biological properties to those reported for the corresponding principles formed in anaphylaxis, and the process of formation was inhibited by oxygen lack and by the above enzyme inhibitors. One noteworthy feature of the spasmogenic lipid formation was that the inhibition caused by anoxia could not be counteracted by glucose. The results support earlier hypotheses regarding the mode of action of phosphatidase A on guinea‐pig lung tissue. It is suggested that mast cells are not necessarily involved in the formation of spasmogenic lipids occurring in connection with histamine release induced by phosphatidase A in the guinea‐pig lung. The bee venom fraction F II, which liberates histamine from rat tissues by a mechanism resembling that of compound 48/80, did not cause release of histamine or formation of spasmogenic lipids from the guinea‐pig lung tissue in concentrations up to 100 mug/ml.
The liberalization and (re)regulation of Dutch gambling markets: National consequences of the changing European context
Authors: Kingma Sytze F.
Published: December 2008

This paper deals with the liberalization of Dutch gambling markets, in particular the (re)regulation of these markets after 2002. It is argued that during the 1990s a neo‐liberal “risk regime” of gambling regulation replaced the traditional moralizing and restrictive gambling policies. However, this risk regime has recently been challenged by the development of Internet gambling, the discussions about the “Services Directive” in the European Parliament and cases brought to the European Court of Justice. These circumstances are redefining the European context for national gambling policies and gambling organizations. Together with a growing risk awareness, this has caused the Dutch government to reconsider its gambling policies. This paper outlines the basic features of the risk regime of gambling regulation, and makes clear that after a decade of great leniency and tremendous market growth, the Dutch gambling markets, including casinos, lotteries and slot machines, were confronted with serious backwashes.
Even clubs can’t do without legitimacy: Why the anti‐money laundering blacklist was suspended
Authors: Hülsse Rainer
Published: December 2008

This article uses the case of anti‐money laundering regulation to investigate international club organisations’ efforts to secure compliance with their rules. As these rules can hardly claim much legitimacy, one would expect that they are complied with only if the club organisation uses side‐payments or coercion. Indeed, the Financial Action Task Force against Money‐Laundering (FATF), the international standard setter in that field, has used blacklisting to force non‐members into compliance. But although it had greatly improved compliance, the blacklist was suspended again after a short period of time. Why? This article argues that this was due to allegations of the blacklist being illegitimate. The FATF reacted by withdrawing the blacklist and also by engaging in various legitimatory practices, because even club organisations need legitimacy if they want to achieve results. Only if the rules are considered legitimate, will there be actual, and not just formal compliance. Hence this article denies the existence of a dilemma between legitimacy and effectiveness (the conventional view), suggesting that only legitimate rules can be effective.
The Rise of the Megachurches and Changes in Religious Culture: Review Article
Authors: Ellingson Stephen
Published: December 2008

Megachurches represent an emerging and powerful force within American Religion. These large, Protestant churches that average at least 2,000 attendees per week are reshaping religion locally, regionally, and nationally as well as at the denominational and congregational levels. Megachurch leaders have been leaders in religious innovation since the 1970s, ushering in major changes in church architecture, ritual practices, polity, and marketing. In this essay, I review the nascent literature on megachurches. First, I discuss the major descriptive findings from several surveys and case studies of megachurches. Second, I examine scholars’ efforts to explain how and why megachurches have emerged and grown over the past forty years. Finally, I suggest several lines of future inquiry that may allow sociologists of religion to extend or refine existing cultural and market based theories of religious change and church‐sect theory.
Effective Thermal Diffusivity of Porous Media in the Wall Vicinity
Authors: Sakamoto H. , Kulacki F. A.
Published: December 2008

Transient heat transfer from an impulsively heated vertical constant heat flux plate embedded in a stationary saturated porous medium is studied experimentally and analytically to determine near-wall thermal diffusivity. The effective diffusivity is shown to depend on the properties of the constituent materials and the near-wall particle morphology. For porous media comprising randomly stacked spheres, the near-wall region is characterized by fewer particle contacts with the wall than in the bulk medium, and this difference is the source of larger thermal diffusivity in the context of volume-averaged values, which apply to the bulk property far from the wall. For combinations of different spherical solids and interstitial fluids, which give a range of fluid:solid conductivity ratio from 0.5 to 2400, early-time transient temperature profiles can be predicted using the thermal conductivity of the interstitial fluid. A conjugate heat transfer analysis accurately predicts the time the conductive front takes to travel through the impermeable wall and quantifies the effect of conduction along the wall on the local and overall Nusselt numbers. The present results raise the possibility of reinterpretation of much of the porous media heat transfer experiments in the literature.
Heat-Transfer Enhancement by Chaotic Advection in the Eccentric Helical Annular Flow
Authors: Mota José P. B. , Rodrigo António J. S. , Saatdjian Estéban
Published: December 2008

Chaotic advection in the eccentric helical annular heat exchanger is investigated as a means to enhance its thermal efficiency. Chaotic streak lines are generated by steadily rotating one boundary while the other is counter-rotated with a time-periodic angular velocity. The effects of the eccentricity ratio and modulation frequency on the heat-transfer rate are analyzed by numerically solving the 3D convection-diffusion equation for a broad range of parameter values. For the frequency range over which chaotic advection can be effectively promoted, the efficiency of the heat exchanger is enhanced over that obtained for steady boundary rotation. Other tools, such as stretching field calculations and streak-line plots, applicable for dissipative dynamical systems, are implemented. These tools qualitatively confirm the quantitative heat-transfer results obtained.
Exergy Analysis of Data Center Thermal Management Systems
Authors: Shah Amip J. , Carey Van P. , Bash Cullen E. , Patel Chandrakant D.
Published: December 2008

The modeling of recirculation patterns in air-cooled data centers is of interest to ensure adequate thermal management of computer racks at increased heat densities. Most metrics that describe recirculation are based exclusively on temperature inside the data center, and therefore fail to provide adequate information regarding the energy efficiency of the thermal infrastructure. This paper addresses this limitation through an exergy analysis of the data center thermal management system. The approach recognizes that the mixing of hot and cold streams in the data center airspace is an irreversible process and must therefore lead to a loss of exergy. Experimental validation in a test data center confirms that such an exergy-based characterization in the cold aisle reflects the same recirculation trends as suggested by traditional temperature-based metrics. Further, by extending the exergy-based model to include irreversibilities from other components of the thermal architecture, it becomes possible to quantify the amount of available energy supplied to the cooling system that is being utilized for thermal management purposes. The energy efficiency of the entire data center cooling system can then be collapsed into the single metric of net exergy loss. When evaluated against a ground state of the external ambience, this metric enables an estimate of how much of the energy emitted into the environment could potentially be harnessed in the form of useful work. Thus, this paper successfully demonstrates that the proposed exergy-based approach can provide a foundation upon which the data center cooling system can be simultaneously evaluated for thermal manageability and energy efficiency.
Temperature Scalings and Profiles in Forced Convection Turbulent Boundary Layers
Authors: Wang Xia , Castillo Luciano , Araya Guillermo
Published: December 2008

Based on the theory of similarity analysis and the analogy between momentum and energy transport equations, the temperature scalings have been derived for forced convection turbulent boundary layers. These scalings are shown to be able to remove the effects of Reynolds number and the pressure gradient on the temperature profile. Furthermore, using the near-asymptotic method and the scalings from the similarity analysis, a power law solution is obtained for the temperature profile in the overlap region. Subsequently, a composite temperature profile is found by further introducing the functions in the wake region and in the near-the-wall region. The proposed composite temperature profile can describe the entire boundary layer from the wall all the way to the outer edge of the turbulent boundary layer at finite Re number. The experimental data and direct numerical simulation (DNS) data with zero pressure gradient and adverse pressure gradient are used to confirm the accuracy of the scalings and the proposed composite temperature profiles. Comparison with the theoretical profiles by Kader (1981, “Temperature and Concentration Profiles in Fully Turbulent Boundary Layers,” Int. J. Heat Mass Transfer, 24, pp. 1541–1544; 1991, “Heat and Mass Transfer in Pressure-Gradient Boundary Layers,” Int. J. Heat Mass Transfer, 34, pp. 2837–2857) shows that the current theory yields a higher accuracy. The error in the mean temperature profile is within 5% when the present theory is compared to the experimental data. Meanwhile, the Stanton number is calculated using the energy and momentum integral equations and the newly proposed composite temperature profile. The calculated Stanton number is consistent with previous experimental results and the DNS data, and the error of the present prediction is less than 5%. In addition, the growth of the thermal boundary layer is obtained from the theory and the average error is less than 5% for the range of Reynolds numbers between 5×105 and 5×106 when compared with the empirical correlation for the experimental data of isothermal boundary layer conditions.
Development of the Damage State Variable for a Unified Creep Plasticity Damage Constitutive Model of the 95.5Sn–3.9Ag–0.6Cu Lead-Free Solder
Authors: Pierce David M. , Sheppard Sheri D. , Fossum Arlo F. , Vianco Paul T. , Neilsen Mike K.
Published: December 2008

A unified creep plasticity damage (UCPD) constitutive model was developed to predict the fatigue of 95.5Sn–3.9Ag–0.6Cu solder joints. Compression, stress-strain and creep properties were generated in previous studies of this solder. Crack damage was reflected in a single state variable, Dω, in the model. Isothermal fatigue tests were performed at 25°C, 100°C, and 160°C using a double-lap shear test specimen. A new approach to fitting the revised damage model is proposed based on finite element analysis (FEA) simulation of the load decay of the fatigued solder material. Accurate predictions required that those parameters be temperature dependent. The UCPD constitutive model was successfully implemented as a subroutine in the commercial finite element code ANSYS®. Consistent predictions were obtained as demonstrated by a comparison of results generated from FEA simulation of the test assembly against analogous experimental results.
Validation of a General Fatigue Life Prediction Methodology for Sn–Ag–Cu Lead-Free Solder Alloy Interconnects
Authors: Pierce David M. , Sheppard Sheri D. , Vianco Paul T. , Regent Jerome A. , Grazier J. Mark
Published: December 2008

A general fatigue life prediction methodology, based on a unified creep plasticity damage (UCPD) model, was developed for predicting fatigue cracks in 95.5Sn–3.9Ag–0.6Cu (wt %) solder interconnects. The methodology was developed from isothermal fatigue tests using a double-lap-shear specimen. Finite element analysis model geometries, mesh densities, and assumptions were detailed for both a full model (an octant-symmetry slice of the entire ball grid array (BGA) assembly) and a submodel (the solder joint deemed most likely to fail and the surrounding package layers) to facilitate fatigue prediction. Model validation was based on the thermal mechanical fatigue of plastic BGA solder joints (250–4000 thermal cycles, −55°Cto125°C, and 10°C∕min). Metallographic cross sections were used to quantitatively measure crack development. The methodology generally underpredicted the crack lengths but, nonetheless, captured the measured crack lengths within a ±2X error band. Possible shortcomings in the methodology, including inaccurate materials properties and part geometries, as well as computational techniques, are discussed in terms of improving both the UCPD constitutive model and the fatigue life prediction methodology fidelity and decreasing the solution time.
Wiresweep Reduction via Direct Cavity Injection During Encapsulation
of Stacked Chip-Scale Packages
Authors: Brand Jason M. , Ruggero Salvatore A. , Shah Amip J.
Published: December 2008

As packaging continues to offer challenges with variable stacked die configurations of increasing complexity, traditional transfer mold encapsulation faces challenges in defining a robust process window. A major concern is the problem of “wiresweep,” wherein deformation of the wirebond during the mold process can potentially cause shortcircuiting. Several prior studies have focused on qualifying the effects of various wirebond and mold process parameters on package wiresweep, but most of these studies are restricted to single (discrete) die packages. This paper attempts to fill this gap of knowledge by experimenting with a variety of test vehicles with different stacking configurations. Specifically, the effects of varying loop height, stack height, and mold compound type are quantified in terms of maximum wiresweep. We find that loop height can have a considerable effect on wiresweep, with the maximum wiresweep being reduced by half (from around 6% to less than 3%) simply by reducing the loop height. Additionally, the study finds that for a given mold process, higher die stacks tend to increase wiresweep, although a threshold stack height exists beyond which further stacking can reduce wiresweep. Lastly, the data suggest that the choice of mold compound can adversely impact wiresweep, especially for test vehicles with traditionally high wiresweep. Having identified these trends, semianalytical models from the literature are used to investigate the cause behind these observations. The analysis suggests that the mold front velocity has the major root impact on package wiresweep. To validate this hypothesis, the series of tests conducted earlier is repeated for a compression mold process, which provides greater control over the mold front velocity. As predicted by the model, significant reduction in wiresweep is achieved. Thus, the compression mold process seems to offer the opportunity for reducing wiresweep without any compromise in the complexity of the die stack.
Damage Initiation and Propagation in Voided Joints: Modeling and Experiment
Authors: Ladani Leila Jannesari , Dasgupta Abhijit
Published: December 2008

This study examines damage initiation and propagation in solder joints with voids, under thermomechanical cyclic loading. An accelerated thermal cycling test is conducted on printed wiring assemblies (PWAs) containing 256 input/output (I/O) plastic ball grid arrays (PBGAs) with voided solder joints. Destructive and nondestructive failure analyses of the solder balls are used to detect the presence of voids and to relate the extent of damage propagation to the number of thermal cycles. Particular cases of voided and damaged joints are selected from these tests, to guide the development of a strategy for modeling damage propagation, using a three dimensional global-local finite element analysis (FEA). The displacement results of the global FEA at the top and bottom of the selected solder balls are used as the boundary conditions in a local FEA model, which focuses on the details of damage initiation and propagation in the individual solder ball. The local model is error seeded with voids based on cases selected in experiment. The damage propagation rate is monitored for all the cases. The technique used to quantify cyclic creep-fatigue damage is a continuum model based on energy partitioning. A method of successive initiation is used to model the growth and propagation of damage in the selected case studies. The modeling approach is qualitatively verified using the results of the accelerated thermal cycling test. The verified modeling technique described above is then used for parametric study of the durability of voided solder balls in a ChipArray Thin Core BGA with 132 I/O (CTBGA132) assemblies, under thermal cycling. The critical solder ball in the package is selected and is error seeded with voids with different sizes and various distances from damage initiation site. The results show that voids in general are not detrimental to thermal cycling durability of the CTBGA132 assembly, except when a large portion of the damage propagation path is covered with voids. Small voids can arrest the damage propagation, but generally do not provide a significant increase in durability because the damage zone deflects around the void and also continues to propagate from other critical regions in the solder ball.
Controlled Weld Toe Profiles for Fatigue Life Extension of T-Butt Joints: An Application to FSOs & FPSOs
Authors: Rodríguez-Sánchez J. Efraín , Rodríguez-Castellanos Alejandro , Carbajal-Romero Manuel F. , Ayala-Uraga Efrén
Published: December 2008

Application of controlled weld toe profiles can be considered an option to extend the fatigue life of welded connections when ongoing tankers are converted in dry docks to serve like offshore ships (FPSOs and FSOs). Very slim chances to implement such fatigue improvement will arise when these vessels are in service, since a converted ship is designed to be inspected, maintained, and repaired in situ and not in dry dock as it is uneconomical to interrupt production. Codes recognize fatigue life extension by means of a controlled weld toe profile (2004, NORSOK Standard N-004 Rev. 2 October). Application of a controlled weld toe profile during conversion in selected areas previously identified by stress analysis of the hull structure can lead to extend the converted vessel fatigue life to comply with an expected field life. The American Bureau of Shipping S-N curves allow a credit of 2.2 on fatigue life when suitable toe grinding and NDE are provided. A controlled weld toe profile can be applied during dry dock ship conversion to FSO or FPSO to welds in a noncracked condition but that were identified prone to fatigue cracking in a stress assessment analysis under new service conditions. Credit on fatigue life in various codes and results from experimental data obtained from fatigue tested specimens with a controlled weld toe profile are given. Comments on the design of a controlled weld toe profiles and recommendations based on experimental experience for the implementation of equipment to perform a controlled weld toe profile are also given. A fracture mechanics approach for the assessment of controlled weld toe profiles for fatigue life extension purposes is described. Initially, a comparison of stress concentration factors for a typical T-butt ship hull plate connection with and without weld toe profile control determined by finite element analysis (FEA) is presented. Results obtained from the FEA connection such as through plate stress distribution are used in a fracture mechanics analysis to compare the fatigue crack growth curve in as-welded condition to that with controlled weld toe profile. It is demonstrated that weld toe profile control is a feasible method to be implemented to improve fatigue life in the order of 2 of T-butt welded connections of ships, which are under conversion to serve as FPSOs or FSOs. This fatigue life extension factor should not be considered at the design stage.
Review of State-Of-The-Art: Drag Forces on Submarine Pipelines and Piles Caused by Landslide or Debris Flow Impact
Authors: Zakeri Arash
Published: December 2008

Submarine landslides and debris flows are among the most destructive geohazards, economically and environmentally, for installations on the seafloor. Estimating the drag forces caused by these geohazards is an important design consideration in offshore engineering. A summary of the major methods available for estimating the drag forces on pipelines and piles caused by a mass gravity soil movement has been presented and compared with one another. The methods available are limited in terms of the application and provide a wide range of estimates. There is significant room for improvement and new research to advance the state-of-the-art.
Aerodynamic Characteristics of Asymmetric Bluff Bodies
Authors: Hu J. C. , Zhou Y.
Published: December 2008

The wake of asymmetric bluff bodies was experimentally measured using particle imaging velocimetry, laser Doppler anemometry, load cell, hotwire, and flow visualization techniques at Re=2600–8500 based on the freestream velocity and the characteristic height of the bluff bodies. Asymmetry is produced by rounding some corners of a square cylinder and leaving others unrounded. It is found that, with increasing corner radius, the flow reversal region is expanded, and the vortex formation length is prolonged. Accordingly, the vortex shedding frequency increases and the base pressure rises, resulting in a reduction in the mean drag as well as the fluctuating drag and lift. It is further found that, while the asymmetric cross section of the cylinder causes the wake centerline to shift toward the sharp corner side of the bluff body, the wake remains globally symmetric about the shifted centerline. The near wake of asymmetric bluff bodies is characterized in detail, including the Reynolds stresses, characteristic velocity, and length scale, and is further compared with that of the symmetric ones.
A Dynamic Model for Ice-Induced Vibration of Structures
Authors: Huang Guojun , Liu Pengfei
Published: December 2008

A dynamic model for the ice-induced vibration (IIV) of structures is developed in the present study. Ice properties have been taken into account, such as the discrete failure, the dependence of the crushing strength on the ice velocity, and the randomness of ice failure. The most important prediction of the model is to capture the resonant frequency lock-in, which is analog to that in the vortex-induced vibration. Based on the model, the mechanism of resonant IIV is discussed. It is found that the dependence of the ice crushing strength on the ice velocity plays an important role in the resonant frequency lock-in of IIV. In addition, an intermittent stochastic resonant vibration is simulated from the model. These predictions are supported by the laboratory and field observations reported. The present model is more productive than the previous models of IIV.
Global Loads on a FPSO Induced by a Set of Freak Waves
Authors: Fonseca Nuno , Guedes Soares C. , Pascoal Ricardo
Published: December 2008

This paper presents a systematic study of the structural loads induced by abnormal waves on a floating production, storage and offloading (FPSO) platform. This work is a follow-up to a previous investigation that explored the possibility of using freak, abnormal, or episodic waves as additional wave load conditions to be considered in the design of ships and offshore platforms. In the previous work, a procedure was developed and implemented to adopt deterministic time series of wave elevation, which may include abnormal waves, as reference design conditions to calculate the wave induced structural loads on ships. An application example was presented for a FPSO subjected to the well known New Year Wave trace that was measured during a severe storm in the Central North Sea. In the present paper, the same procedure is applied to obtain the wave induced structural loads on a FPSO, but a systematic investigation is carried out by using a large set of wave traces. These wave traces have been measured at different occasions in the North Sea, additionally at one location in the Central Gulf of Mexico, and they all include episodic freak waves. In this way it is possible to assess the influence of realistic rogue wave characteristics on the wave induced structural loads. Finally, and based on the platform responses to all wave traces, some statistics are produced regarding the platform responses and structural loads induced by rogue waves.
Maximum Drag Reduction Asymptote of Polymeric Fluid Flow in Coiled Tubing
Authors: Shah Subhash N. , Zhou Yunxu
Published: December 2008

This study experimentally investigates the drag reduction characteristics of the most commonly used polymer fluids in coiled tubing applications. The flow loop employed consists of 12.7mm straight and coiled tubing sections. The curvature ratio (a∕R, where a and R are the radii of the tubing and the reel drum, respectively) investigated is from 0.01 to 0.076, which covers the typical curvature ratio range encountered in the oil and gas industry applications. Fluids tested include xanthan gum, guar gum, and hydroxypropyl guar at various polymer concentrations. It is found that the drag reduction in coiled tubing is significantly lower than that in straight tubing, probably due to the effect of secondary flow in curved geometry. The onset of drag reduction is also found to be delayed as the curvature ratio was increased. A correlation for the maximum drag reduction (MDR) asymptote in coiled tubing is developed. When the curvature ratio is set to zero, the new correlation reduces to the well-known Virk’s MDR asymptote for dilute polymer solutions in straight pipes. A new drag reduction envelope is proposed for the analysis of drag reduction behavior of polymeric fluids in coiled tubing. Application of the new drag reduction envelope is also discussed.
Modeling of Pressure Drop During Condensation in Circular and Noncircular Microchannels
Authors: Agarwal Akhil , Garimella Srinivas
Published: December 2008

This paper presents a multiple flow-regime model for pressure drop during condensation of refrigerant R134a in horizontal microchannels. Condensation pressure drops measured in two circular and six noncircular channels ranging in hydraulic diameter from 0.42mmto0.8mm are considered here. For each tube under consideration, pressure drop measurements were taken over the entire range of qualities from 100% vapor to 100% liquid for five different refrigerant mass fluxes between 150kg∕m2s and 750kg∕m2s. Results from previous work by the authors on condensation flow mechanisms in microchannel geometries were used to assign the applicable flow regime to the data points. Garimella et al. (2005, “Condensation Pressure Drop in Circular Microchannels,” Heat Transfer Eng., 26(3) pp. 1–8) reported a comprehensive model for circular tubes that addresses the progression of the condensation process from the vapor phase to the liquid phase by modifying and combining the pressure drop models for intermittent (Garimella et al., 2002, “An Experimentally Validated Model for Two-Phase Pressure Drop in the Intermittent Flow Regime for Circular Microchannels,” ASME J. Fluids Eng., 124(1), pp. 205–214) and annular (Garimella et al., 2003, “Two-Phase Pressure Drops in the Annular Flow Regime in Circular Microchannels,” 21st IIR International Congress of Refrigeration, International Institute of Refrigeration, p. ICR0360) flows reported earlier by them. This paper presents new condensation pressure drop data on six noncircular channels over the same flow conditions as the previous work on circular channels. In addition, a multiple flow-regime model similar to that developed earlier by Garimella et al. for circular microchannels is developed here for these new cross sections. This combined model accurately predicts condensation pressure drops in the annular, disperse-wave, mist, discrete-wave, and intermittent flow regimes for both circular and noncircular microchannels of similar hydraulic diameters. Overlap and transition regions between the respective regimes are also addressed to yield relatively smooth transitions between the predicted pressure drops. The resulting model predicts 80% of the data within ±25%. The effect of tube shape on pressure drop is also demonstrated.
Dynamic Analysis of a Slender Body of Revolution Berthing to a Wall
Authors: Wang Q. X. , Tan S. K.
Published: December 2008

A slender body of revolution berthing to a wall is studied by extending the classical slender body theory. This topic is of practical importance for a ship berthing to a quay wall. The flow problem is solved analytically using the method of matched asymptotic expansions. The lateral force and yaw moment on the body are obtained in a closed form too. The translation and yawing of the body are modeled using the second Newton law and coupled with the flow induced. Numerical analyses are performed for the dynamic lateral translation and yawing of a slender spheroid, while its horizontal translation parallel to the wall is prescribed at zero speed, constant speed, and time varying speed, respectively. The analysis reveals the interesting dynamic features of the translation and yawing of the body in terms of the forward speed and starting angle of yaw of the body.
Assessment of Tandem Venturi on Enhancement of Cavitational Chemical Reaction
Authors: Sayyaadi Hoseyn
Published: December 2008

The collapsing phenomenon of cavitation bubbles generates extremely high local pressures and temperatures that can be utilized for the chemical oxidation process. This process is carried out in cavitation reactors. A Venturi tube is one of the most common forms of hydrodynamic cavitation reactors, which is suitable for industrial scale applications. In this work, the hydraulic performance and efficiency in chemical reaction of a new form of hydrodynamic cavitation reactors, which is called “tandem Venturi,” were studied and compared with the conventional type of the single Venturi. The tandem Venturi is used for enhancement of the chemical reaction of hydrodynamic cavitating flow. The reaction enhancement is useful especially for the reaction of aqueous solutions not containing volatile organic compounds (VOCs). The operating pressure, inlet pressure, flow rate, and consequently the cavitation number were controlled and systematically varied for both single and tandem Venturis. Moreover, a specified amount of H2O2 was injected into the flow as required. The effects of operating pressure and the cavitation number on cavitating flow characteristics for single and tandem Venturis were experimentally observed and the results were compared. In addition, the performance of the tandem-Venturi reactor for degradation of non-VOC contaminants (2-chlorophenol) was studied. Its performance was compared with the performance of a conventional Venturi reactor. Two different categories were conducted for the experiments. In the first category, the effect of the net cavitating flow on degradation of non-VOC for the single and tandem Venturis was compared. In the second category, the effect of H2O2 injection into the cavitating flow on degradation of non-VOC (“cavitation-oxidation” process) was studied. The performance of the single and tandem Venturis for the cavitation-oxidation process was compared. Further investigation was performed to assess the advantage of utilizing the tandem Venturi from the viewpoint of efficiency of the oxidation process. The results of the energy efficiency were compared with the corresponding efficiency of the single Venturi. Finally, the relationship between the main parameters of cavitation reaction flow with the chemical performance was discussed.
A simple, inexpensive photoelastic modulator
Authors: Braun Kyle J. , Lytle Christian R. , Kavanaugh James A. , Thielen James A. , Green Adam S.
Published: December 2008

A block of birefringent gelatin acts as a variable retarder when driven harmonically by a speaker coil and can be used to vary the polarization of a laser beam sinusoidally. We model this effect with Mueller matrices and show that the gelatin behaves much like a commercial photoelastic modulator and is suitable for a variety of polarimetry experiments in an advanced undergraduate optics course.
A research-based curriculum for teaching the photoelectric effect
Authors: McKagan S. B. , Handley W. , Perkins K. K. , Wieman C. E.
Published: December 2008

We have developed a curriculum on the photoelectric effect including an interactive computer simulation, interactive lectures with peer instruction, and conceptual and mathematical homework problems. Our curriculum addresses established student difficulties and is designed so that students will be able to (1) correctly predict the results of experiments on the photoelectric effect and (2) describe how these results lead to the photon model of light. Our instruction leads to better student mastery of the first goal than either traditional instruction or previous reformed instruction, with approximately 85% of students correctly predicting the results of changes to the experimental conditions. Most students are able to correctly state the observations made in the photoelectric effect experiment and the inferences that can be made from these observations, but are less successful drawing a clear logical connection between the observations and the inferences.
Mechanics of swinging a bat
Authors: Cross Rod
Published: December 2008

Measurements on the swing of a baseball bat are analyzed to extract the basic mechanics of the swing. The force acting on the bat is determined from the velocity of the center of mass, and the angular velocity of the bat provides additional information on the couple exerted by the two hands. The motion of the bat was calculated for other force-couple combinations to determine their effects on the swing of the bat. It was found that a couple is needed to start the swing, and a large opposing couple is required near the end of the swing to prevent the bat rotating through an excessive angle before it impacts with the ball.
Interpretation of the cosmological metric
Authors: Cook Richard J. , Burns M. Shane
Published: December 2008

The cosmological Robertson–Walker metric of general relativity is often said to have the consequences that (1) the recessional velocity v of a galaxy at proper distance ℓ obeys the Hubble law v=Hℓ, and therefore galaxies at sufficiently great distance ℓ are receding faster than the speed of light c; (2) faster than light recession does not violate special relativity theory because the latter is not applicable to the cosmological problem, and because “space itself is receding” faster than c at great distance, and it is velocity relative to local space that is limited by c, not the velocity of distant objects relative to nearby ones; (3) we can see galaxies receding faster than the speed of light; and (4) the cosmological redshift is not a Doppler shift, but is due to a stretching of photon wavelength during propagation in an expanding universe. We present a particular Robertson–Walker metric (an empty universe metric) for which a coordinate transformation shows that none of these interpretation necessarily holds. The resulting paradoxes of interpretation lead to a deeper understanding of the meaning of the cosmological metric.
A balsa violin
Authors: Waltham Chris
Published: December 2008

Almost half a century ago John Schelleng determined the scaling rules that show how violins can be made from nontraditional materials. These principles suggest that balsa wood may be a possible, if unlikely, construction material. To test this idea, a balsa violin was constructed and found to be playable. Its vibrational behavior is shown to be in agreement with Schelleng’s scaling rules. The instrument was not difficult to build, and its construction can be repeated by anyone of moderate skill with a chisel and sandpaper and access to an audio frequency analysis program. The reward is a tactile appreciation for the vibrational behavior of materials and the physics of musical instruments that is difficult to gain otherwise.
Finite element solution of Laplace’s equation for ion-atom chambers
Authors: Golde Jacob , Shertzer Janine , Oxley Paul
Published: December 2008

The finite element method is used to solve Laplace’s equation for ion-atom chambers. We first consider a simplified model chamber for which an analytical solution can be obtained; the model chamber serves as a test case to verify the accuracy and convergence of the finite element method. We apply the finite element method to an experimental chamber consisting of five equipotential rings in a grounded cylindrical shell. We determine the strength and homogeneity of the electric field in the region of the chamber where the atoms undergo laser excitation into a Rydberg state.
The placenta in preterm birth
Authors: Faye-Petersen O M
Published: December 2008

Rates of preterm birth range from 5% to 13% of deliveries in developed countries. About two-thirds of preterm deliveries are due to spontaneous onset of preterm labour or preterm premature rupture of membranes. Approximately one-third follow induction of labour or caesarean section performed for maternal or fetal indications such as preeclampsia, haemorrhage, non-reassuring fetal heart rate or intrauterine growth restriction. Thus, pathologists are frequently called on to evaluate preterm placentas, to determine the cause of the spontaneous preterm birth and/or correlate placental findings with the clinical history. This review provides pathologists with an overview of the recent clinical research in the pathogenesis of preterm birth and relates these to the correlative placental pathologies of the major causes of spontaneous preterm birth. A brief summary of the placental gross and histopathological findings in indicated preterm birth is also included.
Age and stratigraphic–tectonic significance of Proterozoic diabase sheets, Mackenzie Mountains, northwestern Canada
Authors: Armstrong Richard Lee , Eisbacher G. H. , Evans Paul D.
Published: December 2008

Diabase dikes and sills were intruded during a Late Proterozoic phase of extensional tectonics in the northern Canadian Cordillera. This event is strongly expressed in the depositional pattern of formations immediately below and above the base of the Windermere Supergroup. Rb–Sr isochron dates of 766 ± 24 and 769 ± 27 Ma have been obtained for two of the these diabase sheets, which intruded the Tsezotene Formation of the Mackenzie Mountains Supergroup. The emplacement of the diabase sills and dikes may be related to either of two volcanic events in the region, one documented, the other inferred. In either case, emplacement of the diabase at approximately 770 Ma is close to the boundary between the Mackenzie Mountains Supergroup and the overlying Windermere Supergroup, precedes a regional glaciation (Shezal tillite), and reflects a strong accentuation of the west-facing Cordilleran miogeocline.
An ichthyornithiform bird from the Campanian of Canada
Authors: Martin Larry D. , Stewart J. D.
Published: December 2008

The geographic range of the ichthyornithiform birds is extended to the Canadian province of Manitoba. The associated fauna from the Pembina Member of the Vermilion River Formation of southern Manitoba closely resembles that from the Sharon Springs Member of the Pierre Shale Formation in Kansas, South Dakota, and Wyoming.
Rb–Sr isochron ages, magmatic 87Sr/86Sr initial ratios, and oxygen isotope geochemistry of the Proterozoic lava flows and intrusions of the East Arm of Great Slave Lake, Northwest Territories, Canada
Authors: Goff S. P. , Baadsgaard H. , Muehlenbachs K. , Scarfe C. M.
Published: December 2008

Two Rb–Sr isochrons from the oldest (Wilson Island Group) and one of the youngest (Pearson Formation) Proterozoic volcanic units in the East Arm of Great Slave Lake give dates and initial ratios of 1810 ± 19 Ma, 0.7051 ± 0.0008, and 1809 ± 30 Ma, 0.7089 ± 0.0004, respectively. These dates restrict the Great Slave Supergroup entirely to the Aphebian. The Pearson Formation date is interpreted as magmatic, but it is considered to be rapidly followed by a significant metamorphic and tectonic event within the area. Both the above suites and the volcanic formations of intermediate age have undergone metamorphism up to and including epidote–amphibolite facies. A study of remnant clinopyroxene grains from these formations has indicated general increases in δ18O of whole rocks during epidote–actinolite facies metamorphism of 0.4–2.0‰. The tholeiitic volcanic rocks and intrusions all indicated δ18O values typical of modern continental tholeiites (5.9–7.0‰). The highest δ18O came from those suites that were suspected of having been contaminated by crustal material. The estimated initial 87Sr/86Sr ratios of the magmas, both from clinopyroxene separates and isochrons, indicate a mantle origin for early tholeiitic mid-Aphebian diabase (0.7016–0.7017), Union Island Group diabase (0.7021–0.7030), and Sosan Group alkali volcanics (0.7017). The later Jackson gabbro (0.7050–0.7054) and especially the Pearson Formation tholeiitic basalt (0.7089) both show the effects of significant crustal contamination. The evidence for the Wilson Island Group is less decisive but appears to indicate a mantle origin.
Sur la présence de Microcodium (Algue?, Incertae sedis?) dans le Paléozoïque supérieur de l'Arctique canadien
Authors: Mamet B. L. , Roux A.
Published: December 2008

Seven localities yielding Microcodium are described from the Carboniferous and Permian of the Yukon Territory, Axel Heiberg, and Ellesmere. The Microcodium is generally perforating. However, microbreccias and reworked fragments containing Microcodium indicate that this enigmatic taxon was already present in Late Paleozoic time. Microcodium is therefore not necessarily the result of pedogenic Cenozoic alteration of older sediments. Cenozoic inorganic, bacterial, or pedogenic origins are improbable. An algal affinity is more plausible.
New Pennsylvanian(?) syringoporid coral from Kamloops area, British Columbia
Authors: Nelson Samuel J.
Published: December 2008

The first described late Paleozoic syringoporid coral in the Canadian Western Cordillera, Sinopora pascuali sp.nov., is from the Dome Hills area, near Kamloops, British Columbia. It has strong Asiatic affinities. The age of the host rock is considered earliest Pennsylvanian(?).
More rapid analysis of rock slopes
Authors: Cruden D. M.
Published: December 2008

When the normals to two discontinuities forming a tetrahedral wedge in a rock slope lie in the opposite halves of a spherical projection divided by a diameter through the line of intersection of the discontinuities, sliding will take place down the line of intersection of the discontinuities if this is statically possible. This new criterion simplifies the analysis of the stability of rock wedges whose motion is driven only by gravity and resisted only by friction. A factor of safety can be simply calculated for all these wedges from plots of the normals to discontinuities on an overlay of a polar, equal-area spherical projection to which the great circles of a similar equatorial projection have been added. Key words: rock, slope analysis, rock wedge, graphical methods.
Soil movements on permafrost slopes near Fairbanks, Alaska
Authors: Wu Tien H.
Published: December 2008

Many north-facing slopes in the Yukon–Tanana Uplands of Alaska show signs of downhill movements in the form of hummocky surface and leaning trees. Measurements of movements and pore pressures were made at several sites in the Caribou–Poker Creek Research Watershed. It was found that, on slopes with inclinations near 30°, most of the movements occurred immediately after thaw when pore pressures were high.To evaluate the slope stability, the soil strength was measured by direct shear tests. The strength of the moss layer and tree roots was evaluated by performing tension tests on the roots and the moss–root complex. Results of stability analyses show that local failures involving individual wedges are likely. The displacements associated with a wedge slide would result in a hummock or step. The strength of the moss–root complex was found to be a significant factor in the stability of the wedge and of the step. Key words: moss, roots, permafrost, pore pressure, shear strength, slope stability, thaw.
Comparison of observed and calculated slip surface in slope stability calculations
Authors: Talesnick M. , Baker R.
Published: December 2008

This study presents a reanalysis of four documented test embankment failures. Previous analysis of the embankments was done using the simplified Bishop method, for both total and effective stress analyses. The present work makes use of an optimization procedure called SSOPT, which searches a slope for the critical slip surface, without predefining the shape of this surface. This procedure yields reasonable factors of safety and a good estimation of the expected slip surface. This is not always the case for the Bishop-type analyses. Key words: slope stability, slip surface, analysis and observation.