bluuebunny/crossref_metadata_2025 huggingface dataset:
A ‘culturally unsafe’ space? The Somali experience of Christchurch secondary schools
Authors: Humpage Louise
Published: March 2009

Abstract:  School should be a ‘culturally safe’ place, particularly for those students in Christchurch who challenge the city's reputation as a culturally homogeneous space and are thus frequently open to discrimination. A case study focusing on Somali refugee adolescents highlights that Christchurch's secondary schools – like those elsewhere in New Zealand – are not a culturally safe, certain space for all students but rather spatially reconstruct inequalities of gender, class and ethnicity. Yet, Somali students are not passive victims, for they have actively renegotiated these spaces within their schools with varying degrees of success.
Dealing with the Contagion: China and India in the Aftermath of the Subprime Meltdown
Authors: Sharma Shalendra D.
Published: March 2009

What began as a downturn in the US housing sector in the summer of 2007 had mushroomed into a global financial crisis by September 2008: the most severe since the 1930s. Developing countries, including China and India, at first seemingly sheltered from the worst of the turmoil, have not been immune to the contagion's spillover effects. What are China and India's precise vulnerabilities, and what can each do to better insulate their economies from the vagaries of global financial marker turmoil? Equally important, what long‐term strategies must each country adopt to make their economies more resilient to global market downturns?
Pricing to Market: Chinese Export Pricing to the USA after the Peg
Authors: Witte Mark David
Published: March 2009

In July 2005, the Chinese Government unpegged the RMB from the US dollar. As the RMB has followed a remarkably predictable appreciation over time, I examine the price of Chinese exports to the USA after unpegging the exchange rate. Results suggest that the Chinese industries with greater import market share were able to raise their prices after the removal of the pegged exchange rate regime; however, over time there is a significant deflationary trend. Chinese export prices tended to decrease under an unanticipated RMB appreciation; this effect was more pronounced for industries with more pricing flexibility. This suggests that Chinese exporters are consistently “pricing to market” and thus creating a significant foreign exchange policy implication. Specifically, a more flexible exchange rate regime will likely have little impact on the prices of Chinese exports to the USA but might increase the profit volatility of Chinese firms.
Rise and Fall of the First Financial Futures Market in China: The Case of Chinese Government Bond Futures
Authors: Chen Chao , Zhou Zhong‐guo
Published: March 2009

This paper studies the rise and fall of the first financial futures market in China. We compare the characteristics in the Chinese Government bond futures market with those in the US T‐bond futures market. They differ in market design and structure, market governance, margin requirements, position limits, delivery process, and the way in which the settlement price is calculated. Furthermore, with a unique dataset, we show that prior to maturities of government bond futures, traders began to accumulate significant amounts of long positions for several selected contracts without the intention to offset, forcing short position holders to either purchase deliverable bonds or offset futures at highly inflated prices, causing higher market volatility and price disequilibrium in both spot and futures markets. Arbitrage opportunity arises and the market eventually collapses. The lessons learned from the suspension of the Chinese Government bond futures market offer an invaluable learning experience.
Karl Pearson in Russian Contexts
Authors: Seneta Eugene
Published: March 2009

The confluence of statistics and probability into mathematical statistics in the Russian Empire through the interaction, 1910–1917, of A.A. Chuprov and A.A. Markov was influenced by the writings of the English Biometric School, especially those of Karl Pearson. The appearance of the Russian‐language exposition of Pearsonian ideas by E. E. Slutsky in 1912 was instrumental in this confluence. Slutsky's predecessors in such writings (Lakhtin, Orzhentskii, and Leontovich) were variously of mathematical, political economy, and biological backgrounds. Work emanating from the interpolational nature of Pearson's system of frequency curves was continued subsequently through the work of Markov, Bernstein, Romanovsky, and Kravchuk (Krawtchouk), who laid a solid probabilistic foundation. The correlational nature in the interpolational early work of Chebyshev, and work of the English Biometric School in the guise of linear least‐squares fitting exposited as the main component of Slutsky's book, was developed in population as well as sample context by Chuprov. He also championed the expectation operation in providing exact relations between sample and population moments, in direct interaction with Karl Pearson. Romanovsky emerges as the most adaptive and modern mathematical statistician.
Karl Pearson and the Establishment of Mathematical Statistics
Authors: Magnello M. Eileen
Published: March 2009

At the end of the nineteenth century, the content and practice of statistics underwent a series of transitions that led to its emergence as a highly specialised mathematical discipline. These intellectual and later institutional changes were, in part, brought about by a mathematical‐statistical translation of Charles Darwin's redefinition of the biological species as something that could be viewed in terms of populations. Karl Pearson and W.F.R. Weldon's mathematical reconceptualisation of Darwinian biological variation and “statistical” population of species in the 1890s provided the framework within which a major paradigmatic shift occurred in statistical techniques and theory. Weldon's work on the shore crab in Naples and Plymouth from 1892 to 1895 not only brought them into the forefront of ideas of speciation and provided the impetus to Pearson's earliest statistical innovations, but it also led to Pearson shifting his professional interests from having had an established career as a mathematical physicist to developing one as a biometrician. The innovative statistical work Pearson undertook with Weldon in 1892 and later with Francis Galton in 1894 enabled him to lay the foundations of modern mathematical statistics. While Pearson's diverse publications, his establishment of four laboratories and the creation of new academic departments underscore the plurality of his work, the main focus of his life‐long career was in the establishment and promulgation of his statistical methodology.
Use of an Electronic Medical Record to Characterize Cases of Intermediate Statin‐Induced Muscle Toxicity
Authors: Mareedu Ravi K. , Modhia Falgun M. , Kanin Elenita I. , Linneman James G. , Kitchner Terrie , McCarty Catherine A. , Krauss Ronald M. , Wilke Russell A.
Published: March 2009

Statin use can be accompanied by a variety of musculoskeletal complaints. The authors describe the clinical characteristics of case patients who experienced adverse statin‐induced musculoskeletal symptoms within a large population‐based cohort in Central Wisconsin. Case status was determined based on elevated serum creatine kinase (CK) levels and the presence of at least 1 physician note reflecting an increased index of suspicion for statin intolerance. From the medical records of nearly 2 million unique patients, the authors identified more than 20,000 potential study patients (∼1%) having CK data and at least 1 exposure to a statin drug. Manual screening was completed on 2227 patients with CK levels in the upper 10th percentile. Of those screened, 267 met inclusion criteria (12.0% eligibility) and 218 agreed to participate in a retrospective study characterizing the risk determinants of statin‐induced muscle toxicity. Three categoric pain variables were graded retrospectively (distribution, location, and severity of pain). The presenting complaints of the case patients were extremely heterogeneous. The number of patients with a compelling pain syndrome (diffuse, proximal muscle pain of high intensity) increased at higher serum CK levels; the number of patients with indeterminate pain variables decreased at higher serum CK levels. The lines reflecting these relationships cross at a CK level of approximately 1175 U/L, approximately half the threshold level needed to make a clinical diagnosis of “myopathy” (ie, CK >10‐fold the upper limit of normal).
The Problem of Stent Thrombosis Associated With Drug‐Eluting Stents and the Optimal Duration of Dual Antiplatelet Therapy
Authors: Ayyanathan Susana , Hersh David , Coplan Neil L. , Garratt Kirk
Published: March 2009

Drug‐eluting stents have significantly reduced the problem of restenosis, but there is an association between drug‐eluting stents and stent thrombosis that can be a significant clinical problem resulting in myocardial infarction or death. The risk for stent thrombosis increases in certain clinical situations and has been reduced through the use of dual antiplatelet therapy for prolonged periods. Until new therapies are developed, it is essential that patients who have had drug‐eluting stents implanted continue with dual‐antiplatelet therapy for at least 1 year and possibly for an indefinite period.
Dealing with Guilt in the German Democratic Republic after 1989
Authors: Falcke Heino
Published: March 2009

After 1989, the churches in East Germany were initially hailed as having played a crucial role in the downfall of Communism, yet within a couple of years, accusations that they had collaborated with the Communist system returned, fanned by the publication of documents from the archive of the Ministry of State Security – the “Stasi”. In particular, the spotlight fell upon the Protestant church's self‐assigned role of being a “Church within Socialism”, which according to critics was at best an attempt to curry favour with the authorities, and at worst a denial of the church's confessional basis. This is an extract from a longer article1 from 2002 in which Falcke places the issue of dealing with the past of the GDR in the context of the wider issue of the way in which the history of the Third Reich and the Holocaust was dealt with in East Germany. In this extract, Falcke reviews the debate of the 1990s, criticizing the fact that the issue of the integrity and guilt of the Protestant churches in the GDR was addressed too frequently in isolation, with little comparison with the wider ecumenical movement, and highlighting the lack of any critical debate about the process of German unification itself. Instead of a paradigm shift as demanded by the Conciliar Process for Justice, Peace and the Integrity of Creation, there was simply a change of system, from socialism through privatization to neo‐liberalism, thus raising new questions about guilt and integrity.
Successful treatment of pulmonary metastases associated with advanced hepatocellular carcinoma by systemic 5‐fluorouracil combined with interferon‐α in a hemodialysis patient
Authors: Katamura Yoshio , Aikata Hiroshi , Kimura Yuki , Azakami Takahiro , Kawaoka Tomokazu , Takaki Shintaro , Waki Koji , Hiramatsu Akira , Kawakami Yoshiiku , Takahashi Shoichi , Chayama Kazuaki
Published: March 2009

A 54‐year‐old man maintained on hemodialysis had a relapse of multiple pulmonary metastases after multimodal therapy for primary hepatocellular carcinoma (HCC). He was treated with tegafur‐uracil (UFT; 400 mg/day) and interferon alfa (IFN‐α; 5 × 106 units three times per week) for 4 weeks. Following this he was treated with systemic 5‐fluorouracil (5‐FU; 1000 mg/day, 5 days per week) and cisplatin (CDDP; 10 mg/day, 5 days per week for 2 weeks). The response to the above treatments was inadequate; pulmonary metastasis deteriorated. Finally, we selected systemic chemotherapy of 5‐FU (750 mg/day, 5 days per week) and recombinant IFN‐α‐2b (3 × 106 units three times per week) for 2 weeks. This therapy resulted in excellent shrinkage of pulmonary metastases, without severe adverse reactions. Hemodialysis was performed three times a week. We report a case of successful treatment of pulmonary metastases by systemic combination chemotherapy of 5‐FU–IFN, previously unsuccessfully treated with UFT–IFN and 5‐FU–CDDP in a patient on hemodialysis. Further studies are needed to select appropriate drugs with fluoropyrimidine‐based systemic chemotherapy, and to analyze the pharmacokinetics of those agents in hemodialysis patients with HCC and extrahepatic metastases.
Managing Functional Biases in Organizational Forecasts: A Case Study of Consensus Forecasting in Supply Chain Planning
Authors: Oliva Rogelio , Watson Noel
Published: March 2009

To date, little research has been done on managing the organizational and political dimensions of generating and improving forecasts in corporate settings. We examine the implementation of a supply chain planning process at a consumer electronics company, concentrating on the forecasting approach around which the process revolves. Our analysis focuses on the forecasting process and how it mediates and accommodates the functional biases that can impair the forecast accuracy. We categorize the sources of functional bias into intentional, driven by misalignment of incentives and the disposition of power within the organization, and unintentional, resulting from informational and procedural blind spots. We show that the forecasting process, together with the supporting mechanisms of information exchange and elicitation of assumptions, is capable of managing the potential political conflict and the informational and procedural shortcomings. We also show that the creation of an independent group responsible for managing the forecasting process, an approach that we distinguish from generating forecasts directly, can stabilize the political dimension sufficiently to enable process improvement to be steered. Finally, we find that while a coordination system—the relevant processes, roles and responsibilities, and structure—can be designed to address existing individual and functional biases in the organization, the new coordination system will in turn generate new individual and functional biases. The introduced framework of functional biases (whether those biases are intentional or not), the analysis of the political dimension of the forecasting process, and the idea of a coordination system are new constructs to better understand the interface between operations management and other functions.
Acquisition Management Under Fluctuating Raw Material Prices
Authors: Yang Jian , Xia Yusen
Published: March 2009

We study a continuous‐review acquisition problem, in which the raw material price follows a discrete‐state Markov process and demand is compound Poisson. We show that one optimal policy is of the order‐up‐to type. Under our mean reversion and time continuity conditions, we further show that the order‐up‐to levels are decreasing at the current price level. At the same time, our computational study verifies that both conditions are indispensable for the monotonicity result. The study also hints at the connection between discrete‐ and continuous‐state price processes.
Demand Forecast Sharing in Supply Chains
Authors: Mishra Birendra K. , Raghunathan Srinivasan , Yue Xiaohang
Published: March 2009

This paper examines the incentives of a manufacturer and a retailer to share their demand forecasts. The demand at the retailer is a linearly decreasing function of price. The manufacturer sets the wholesale price first, and the retailer sets the retail price after observing the wholesale price. Both players set their prices based on their forecasts of demand. In the make‐to‐order scenario, the manufacturer sets the production quantity after observing the actual demand; in the make‐to‐stock scenario, the manufacturer sets the production quantity before the demand is realized. In the make‐to‐order scenario, we show that sharing the forecast unconditionally by the retailer with the manufacturer benefits the manufacturer but hurts the retailer. We also demonstrate that a side payment contract cannot induce Pareto‐optimal information sharing equilibrium, but a discount based wholesale price contract can. The social welfare as well as consumer surplus is higher under the discount contract, compared with under no information sharing. In the make‐to‐stock scenario, the manufacturer realizes additional benefits in the form of savings in inventory holding and shortage costs when forecasts are shared. If the savings from inventory holding and shortage costs because of information sharing are sufficiently high, then a side payment contract that induces Pareto‐optimal information sharing is feasible in the make‐to‐stock scenario. We also provide additional managerial insights with the help of a computational study.
Supply Chain Strategies for Perishable Products: The Case of Fresh Produce
Authors: Blackburn Joseph , Scudder Gary
Published: March 2009

This paper examines supply chain design strategies for a specific type of perishable product—fresh produce—using melons and sweet corn as examples. Melons and other types of produce reach their peak value at the time of harvest; product value deteriorates exponentially post‐harvest until the product is cooled to dampen the deterioration. Using the product's marginal value of time (MVT), the rate at which the product loses value over time in the supply chain, we show that the appropriate model to minimize lost value in the supply chain is a hybrid of a responsive model from post‐harvest to cooling, followed by an efficient model in the remainder of the chain. We also show that these two segments of the supply chain are only loosely linked, implying that little coordination is required across the chain to achieve value maximization. The models we develop also provide insights into the use of a product's MVT to develop supply chain strategies for other perishable products.
Optimal Pricing, Ordering, and Return Policies for Consumer Goods
Authors: Ketzenberg Michael E. , Zuidwijk Rob A.
Published: March 2009

Our research addresses a firm that sells a product to consumers who are sensitive to both price and return policy. The operational decisions of interest are the selling price, return policy, and quantity of new product to purchase. We model a single selling season that is split into two periods where the boundary between periods is delineated by the opportunity to recover product returns and resell them. That is, returns in the first period can be recovered and sold in the second period. Returns also arise in the second period, but these may only be salvaged. We first analyze both deterministic and stochastic models, finding that the deterministic results largely carry over to the stochastic case. In addition, our results indicate that the model is quite insensitive to errors in the estimates of the parameter values, except for purchase cost and parameters related to demand. Finally, we perform an analysis on the value of various investments to improve financial performance. Results indicate that investments to reduce the recovery cost of returns or reduce returns uncertainty are minimal, while investments to increase recovery speed, reduce market uncertainty, and reduce the return rate can be quite valuable.
Improving Performance in Outpatient Appointment Services with a Simulation Optimization Approach
Authors: Klassen Kenneth J. , Yoogalingam Reena
Published: March 2009

Outpatient health care service providers face increasing pressure to improve the quality of their service through effective scheduling of appointments. In this paper, a simulation optimization approach is used to determine optimal rules for a stochastic appointment scheduling problem. This approach allows for the consideration of more variables and factors in modeling this system than in prior studies, providing more flexibility in setting policy under various problem settings and environmental factors. Results show that the dome scheduling rule proposed in prior literature is robust, but practitioners could benefit from considering a flatter, “plateau‐dome.” The plateau–dome scheduling pattern is shown to be robust over many different performance measures and scenarios. Furthermore, because this is the first application of simulation optimization to appointment scheduling, other insights are gleaned that were not possible with prior methodologies.
Failure Analysis of the Rotor-Journal Bearing System of Rotary Compressor
Authors: Xie Fei , Huang Bo , Zhang Haifeng , Liu Chunhui
Published: March 2009

Rotary compressor has been widely used in room air conditioner. During development of the new compressor, the abrasion of bearings and the break of crankshaft frequently occurred. So it is very important to build a numerical method to estimate the reliability of the compressor. The rotor-journal bearing system is numerically solved as a dynamic nonlinear fluid-structure interaction problem in this paper. The finite element models of the rotor and bearing housings are built up by using the Timoshenko beam model. In order to get the oil film pressure of the journal bearing, Reynolds equation is solved by variation principle, and the finite element method is used to discrete the oil film. An iterative method based on the complimentary principle is used to solve the oil film force and the Reynolds boundary simultaneously. Through analysis, the abrasion position between the bearing and shaft is presented, and the bending tension stress shows the dangerous sections of the crankshaft. Through the distribution of the oil pressure, position of the screw oil groove, which is built on the inside of the bearing housing to supply the oil to lubricate the bearing, is determined. The proper position of the radial oil hole on shaft is decided by analysis of the bending tension stress.
Imaging a Gas-Sparged Stirred-Tank Reactor With X-Ray CT
Authors: Ford Jason J. , Heindel Theodore J. , Jensen Terrence C.
Published: March 2009

X-ray computed tomography (CT) is used to explore the differences in gas dispersion in a gas-sparged stirred-tank reactor (STR) for different operating conditions. X-ray CT imaging is completed for various impeller speeds and gas flow rates in a 0.21 m ID STR made out of acrylic and equipped with a nylon Rushton-type impeller. From the CT slices, major differences in local time-averaged gas holdup can be seen, depending on the operating condition. Completely dispersed conditions have a relatively uniform holdup profile while flooded conditions have an increase in gas holdup towards the center of the tank. The high resolution of the X-ray system allows for visualizing time-averaged gas flow details such as low gas holdup regions directly above the impeller region under certain operating conditions and recirculation regions behind the baffles.
Micro Vortex Flow Induced by Small Life
Authors: Mochizuki O.
Published: March 2009

We investigated the relations between swimming motions and flow fields around plankton that is a larva of brine-shrimp (Artemia salina) and jellyfish (Aurelia aurita). These move in low Reynolds numbers by flapping motion in common. We recorded motions and flow by using a high speed CCD camera, and analyzed by a motion analysis and PIV method. We observed vortex pairs in each case as a result of power stroke and recovery stroke of pitching motion. Force acting on the body was estimated by measured acceleration of the body. Mechanism of generation of thrust force related to vortex pairs by flapping motion in low Reynolds number environment was discussed in this paper.
Particle Image Velocimetry for Air Flows Behind Permeable Cylinders
Authors: Takeuchi Hirotaka , Tasaka Yuji , Murai Yuichi , Takeda Yasushi , Tezuka Hideaki , Mori Michitsugu
Published: March 2009

Particle image velocimetry is applied to measurement of airflows around three types of permeable circular cylinders. The experimental model of the permeable cylinder is made of squared meshed sheet rolled in circle. Water mist smoke is used as air tracer, which is generated with dry ice in a chamber to produce fine spatial density fluctuation for guaranteeing the PIV quality. Since the flow involves fluctuation in a very wide wavenumber from the cylinder size to mesh-dependent eddies, calculating brightness spectrum quantitatively assesses the smoke image quality. The experiment is carried out in an open type wind tunnel. The following results are obtained when the measurement results are compared to those of a solid cylinder. 1: The flow just behind the cylinder has forward velocity due to the permeability while the solid cylinder has reverse flow in the wake. This feature relaxes near field excitation of Karman vortex shedding. 2: The reattachment point behind the cylinder displaces several times as the solid case. As a result of the above two phenomena, the peak potion of the turbulence energy appears in the far downstream region as the permeability of the cylinder increases.
Dynamics and Optics of Bubble Tracking Velocimetry for Airflow Measurement
Authors: Kanda Tetsushi , Murai Yuichi , Tasaka Yuji , Takeda Yasushi
Published: March 2009

Availability of particle tracking velocimetry (PTV) that is applied to movie images of soap bubbles in airflow is investigated experimentally. This study is positioned as a basic research for measuring environmental flow with a large spatial scale, such as flows around building, trees, and near-ground airflow boundary layer. Instead of solid fine particles, soap bubbles are used as the airflow tracer for reducing environmental impact. Typical bubble size provided by the present bubble generator is controlled around 20mm, at which the bubbles obviously have relative velocity to the airflow. We report three topics on the bubble tracking velocimetry (BTV) in this paper: 1) optics of bubble-imaging for quantitative visualization, and application to 3-D visualization using color illumination, 2) theoretical estimation of bubble’s relative velocity to airflow based on an equation of bubble’s translational motion, 3) comparison of velocity vector field obtained by the BTV with that from cross-correlation PIV applied for smoke image. For the latter two topics, airflow around a NACA airfoil is chosen as the target of BTV measurement since it causes significant slip motion of soap bubbles from the airflow that accompanies shear rate, convective acceleration, pressure gradient, and separation.
Mechanical Conversion of Thermal Energy at Room Temperature
Authors: Gim Syqho
Published: March 2009

We consider atmospheric environment itself as the thermal energy resource. In order to utilize this terestrial environment energy sources into practical form we suggest, as the heat sink, the cold air in the altitude above 10 km from the ground. The construction of tower to this height is discussed. For the generation of 1 GW power the economical column size of the tower is on the average around 350 m. By taking into considerations of dissipation energy due to air circulation, surface radiation, water drag force and etc., the overall conversion efficiency of 16% is achieved. This mechanical conversionsystem of thermal energy at room temperature is expected intrinsically to be pollution free and the resources are virtually unlimited.
Multiphase Transport With Conventional and Newly Designed Twin Screw Pumps in a Pipeline Network
Authors: Aleksieva Galabina , Scharf Alexander , Mewes Dieter , Rohlfing Gerhard , Reichwage Mark
Published: March 2009

Twin screw pumps are displacement pumps, working with two axially parallel and countercurrently rotating screws. They are experimentally and theoretically investigated by variation of the boundary conditions at the suction and discharge side of the pump. These are defined by the multi-phase flow patterns in the pipeline system of the closed loop test facility which is operated with oil, gas and water. Because of the efficient continuously operated phase separation, the plant is suited for the experimental investigation of the delivery characteristics in dependence of different flow patterns as well as modifications of the pump construction. A newly designed pair of screws (fig.1) with declining pitch is proposed for operation. The delivery of the pump depends on the declining volumes of the chambers, formed by the intermeshing screws moving from the suction to the discharge side. The improved performance of gas compression gives advantages in the efficiency of power consumption especially for multiphase pumping of mixtures with increasing gas volume flow fractions. By comparison with non-declining screws, the isothermal efficiency for declining screws is increased.
Confined Swirling Flows of Aqueous Surfactant Solutions Due to a Rotating Disc in a Cylindrical Casing
Authors: Tamano S. , Itoh M. , Yoshida M. , Yokota K.
Published: March 2009

In this study, confined swirling flows of an aqueous surfactant solution due to a rotating disc in a cylindrical casing were investigated using a sectional flow visualization technique and a two-component laser Doppler velocimetry (LDV) system. The concentrations of aqueous surfactant solutions (C14TASal) are 0.4, 0.8, and 1.2 wt%. Rheological properties such as a shear viscosity and a first normal stress difference of the surfactant solution were measured with a rheometer. The patterns of the secondary flow were classified using the Reynolds and elastic numbers. We revealed that the projection formed near the center of the rotating disc was moving up and down at a constant frequency for C14TASal 0.8 and 1.2 wt%, which has not been reported as far as we know. The effects of the Reynolds number, elastic number, and aspect ratio on the velocity profiles were clarified. It was also found that the region of rigid body rotation existed at the higher Reynolds number tested for C14TASal 0.4 wt%.
LES Analysis of Engine Steady Intake Flows Using a Mixed-Time-Scale SGS Model
Authors: Inagaki Masahide , Nagaoka Makoto , Horinouchi Nariaki , Suga Kazuhiko
Published: March 2009

Large eddy simulation (LES) using a mixed-time-scale (MTS) SGS model is applied to the intake flows in simplified internal combustion engine geometry. A modified colocated grid system is employed so as to perform calculations stably with a central difference scheme for convection terms. The results are compared with corresponding experimental data and the computational results obtained by using the low-Reynolds-number linear k-ε and cubic nonlinear k-ε -A2 turbulence models. The LES results show the best agreement with experimental data in three computational cases, not only in the mean velocity profiles but also in the profiles of turbulent energy. These results suggest that LES using the MTS model is an effective method for accurately predicting the performance of a combustion engine involving turbulent diffusion of spray and combustion flame. In addition, it is clarified that the numerical viscosity from the QUICK scheme for the convection term has a great influence on the computational results and decreases the prediction accuracy of LES.
Experimental and Numerical Investigation of a Centrifugal Nozzle
Authors: Smith Jason , Eli Robert N.
Published: March 2009

This paper reports on a laboratory experiment conducted more than 30 years ago (Eli, 1974, unpublished), and recent Computational Fluid Dynamics (CFD) investigations, focusing on the properties of a plane tangential jet produced by an apparatus called a “centrifugal nozzle.” The authors believe that the centrifugal nozzle has potential industrial applications in several areas related to fluid mixing and particulate matter suspension in mixing tanks. It is also believed that this experiment, or one similar, may provide data useful for benchmarking CFD models.
Numerical Study of Effects of Initial Flow Field on Taylor Vortex Flow
Authors: Furukawa H. , Hanaki M. , Watanabe T.
Published: March 2009

In concentrically rotating double cylinders consisting of a stationary outer cylinder and a rotating inner cylinder, Taylor vortex flow appears. Taylor vortex flow occurs in journal bearings, various fluid machineries, containers for chemical reaction, and other rotating components. Therefore, the analysis of the flow structure of Taylor vortex flow is highly effective for its control. The main parameters that determine the modes of Taylor vortex flow of a finite length are the aspect ratio Γ, Reynolds number Re. Γ is defined as the ratio of the cylinder length to the gap length between cylinders, and Re is determined on the basis of the angular speed of the inner cylinder. Γ was set to be 3.2, 4.8 and 6.8, and Re to be values in the range from 100 to 1000 at intervals of 100. Thus far, a large number of studies on Taylor vortex flow have been carried out; however, the effects of the differences in initial conditions have not yet been sufficiently clarified. In this study, we changed the initial flow field between the inner and outer cylinders in a numerical analysis, and examined the resulting changes in the mode formation and bifurcation processes. In this study, the initial speed distribution factor α was defined to be a function of the initial flow field and set to be 1.0, 0.999, 0.9 and 0.8 for the calculation. As a result, a difference was observed in the final mode depending on the difference in α for each Γ. From this finding, non-uniqueness, which is a major characteristic of Taylor vortex flow, was confirmed. However, no regularities regarding the difference in mode formation were found and the tendency of the mode formation process was not specified. Moreover, the processes of developing the vortex resulting in different final modes were monitored over time by visual observation. Similar flow behaviors were initially observed after the start of the calculation. Then, a bifurcation point, at which the flow changed to a mode depending on α, was observed, and finally the flow became steady. In addition, there was also a difference in the time taken for the flow to reach the steady state. These findings are based on only visual observation. Accordingly, a more detailed analysis at each lattice point and a comparison of physical quantities, such as kinetic energy and enstrophy, will be our future tasks.
Ultrasonic Measurement of Instantaneous Velocity Vector Profile
Authors: Takeda Yasushi , Tasaka Yuji
Published: March 2009

This paper proposes a new technique that enables the measurement of an instantaneous velocity vector profile in multi-dimensions on a line of the flow field. A system to achieve this goal was developed based on ultrasonic velocity profiling (UVP) by using multiple transducers. A focusing transducer, which reduces the effective diameter of ultrasonic beams around the focal point, was used to minimize the spatial uncertainty in the measurement. A two-dimensional system was constructed by using a normal transducer as a receiver and a focusing transducer as both an emitter and a receiver, and successfully applied to an actual flow field, rigid body motion of fluid in a rotating cylinder, for two-dimensional velocity vector measurements. To estimate the influence of existence of an intermediate wall, acoustic field under the developed system was computed by solving two-dimensional wave equation and then the focal point of an ultrasonic beam was determined to optimize the system. The system was applied to measure two dimensional velocity components of a periodic velocity fluctuation in a wake of a cylinder in a shallow channel as an example of unsteady flow. Obtained temporal variation of velocity vector profile confirmed an applicability of the developed system to unsteady flow. The vortex shedding in the wake was well reproduced as in the vorticity distribution, which was computed from the temporal variation of the vector field using Taylor frozen hypothesis. Although a temporal resolution is still not high, we conclude that applicability of the measurement system has been confirmed.
Environmental Flow Field Measurement by Ultrasonic Velocity Profiling
Authors: Tasaka Yuji , Takeda Yasushi , Yokoyama Kaoru , Kojima Shinya
Published: March 2009

Ultrasonic velocity profiling (UVP) was applied to an environmental flow attempting an efficient measurement of river flow with higher accuracy in comparison with current measurement methods. Applicability of the method on measurement of an open channel flow was confirmed in a laboratory experiment; namely, the cross sectional velocity distribution of the channel was measured; the flow rate was obtained by integrating the velocity distribution; this showed high accuracy, around 4% in relative error. The method detecting the bottom position of the channel from a single velocity profile was also established and was demonstrated by various boundary conditions at the bottom of the channel. Actual river measurements were performed at a creek flowing out of a small pond in the campus of Hokkaido University; the width of the creek is approximately 1700 mm. Measured velocity distribution at a cross section of the river represents well the flow field. The bottom position of the river detected by the established method corresponds to that measured by a ruler excluding a place covered by waterweed. The flow rate determined by integrating the velocity distribution is in good agreement with that estimated by a weir mounted at the inlet of the river.
Wall Asymptotic Behavior of Subgrid Scale Stress for Large Eddy Simulation
Authors: Morinishi Y. , Nakamura E.
Published: March 2009

The objective of this study is to specify the wall asymptotic behavior of the subgrid scale stress for the large eddy simulation (LES) of wall bounded turbulent flows. The grid scale (GS) and subgrid scale (SGS) turbulent statistics are extracted from the numerical data of direct numerical simulation (DNS) of the turbulent channel flow at the Reynolds number of 300, based on the friction velocity and channel half width, in order to achieve this objective. The basic equations of the DNS are the Navier-Stokes and continuity equations for incompressible flows. The GS and SGS statistics are computed corresponding to various LES filters, that is, two-dimensional (plane) and three-dimensional filters with different filter widths. The Gaussian filter is used in the periodic directions. The filtering function in the wall-normal direction is top-hat for the three-dimensional filter. Then, the components of the SGS stress are compared with the analytical results by the Taylor expansion. The results estimated by the Taylor expansion and the DNS data indicate different wall asymptotic behaviors of the SGS stress for the plane and three-dimensional filters. In particular, the wall asymptotic behavior of the Reynolds stress, which has been assumed in the SGS modeling, is not true of the SGS stress for the three-dimensional filter.
The Application of Shape Memory Alloy as Vortex Generators and Flow Control Devices for Enhanced Convective Heat Transfer
Authors: Aris Mohd. S. , Owen Ieuan , Sutcliffe Chris. J.
Published: March 2009

This paper is concerned with convective heat transfer enhancement of heated surfaces through the use of vortex generators and flow control devices. A preliminary proof-of-concept investigation has been carried out into the use of active vortex generators and flow control elements, both manufactured from Shape Memory Alloys (SMAs) which are activated at set temperatures. The vortex generators change their shape to intrude further into the flow at high temperature to enhance heat transfer, while they maintain a low profile at low temperatures to minimise flow pressure losses. One set of vortex generators was made from pre-alloyed powders of SMA material in an advanced rapid prototyping process known as Selective Laser Melting (SLM). Another set of devices was also made from commercially available flat annealed thin SMA sheets for comparison purposes. The flow control elements are devices that preferentially guide the flow to heated parts of a surface, again using temperature-activated SMAs. Promising results were obtained for both the vortex generator and flow control device when their temperatures were varied from 20° to 85°C. The vortex generators responded by increasing their angle of attack from 20° to 35° while the wavy flow control elements straightened out at higher temperatures. As the designs were two-way trained, they regain their initial position and shape at a lower temperature. The surface temperature of the heated plate on which the active devices were positioned reduced between 8 to 51%, indicating heat transfer enhancement due to the generated vortices and changes in air flow rates.
Optimization of Cold Gas Dynamic Spray Processes by Computational Simulation
Authors: Takana Hidemasa , Ogawa Kazuhiro , Shoji Tetsuo , Nishiyama Hideya
Published: March 2009

An integrated model of compressible thermofluid, splat formation and coating formation for a cold dynamic spray process has been established. In-flight behavior of nano-micro particles and the interaction between the shock wave and the particles in a supersonic jet flow impinging onto the substrate and further particle acceleration with electrostatic force are clarified in detail by considering viscous drag force, flow acceleration, added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis and electrostatic force. The effect of electrostatic acceleration becomes more significant with the decrease in particle diameter even in the presence of unavoidable shock wave. As a result, electrostatic acceleration can broaden the application range of operating particle diameter in a cold gas dynamic spray process to form a robust and activated coating. Finally, based on the integrated model, the coating thickness characteristics in an electrostatic assisted cold dynamic spray process are evaluated.
Large Scale Geometrical Aspects of Turbulent Jet Scalar Regions and Interfaces: Measurement and Modeling
Authors: Shockro Jennifer , Catrakis Haris J.
Published: March 2009

This study focuses on the measurement and modeling of large scale geometrical aspects of turbulent jet scalar regions and interfaces. While several previous studies have focused on the small scale geometrical properties using fractal ideas, examination of the large scale geometrical aspects requires the development of what we call generalized fractals, i.e. the scale-dependent generalization of the original self-similar geometric framework. Our work involves the purely meshless approach to the determination of the generalized fractal properties, pioneered by Catrakis, that eliminates the need for grid-based box counting. We investigate the purely meshless generalized fractal approach using experimental databases generated in our laboratories on fully-developed turbulent jets with a Reynolds number of Re ∼ 20,000 and a Schmidt number of Sc ∼ 2,000. In our approach, we examine the dependence of the generalized fractal aspects of the turbulent interfaces at various spatial resolution scales. Our results indicate that the large scale geometrical aspects are strongly scale dependent and amenable to modeling using generalized fractal functions.
Dual-Plane Stereo-PIV Study on Tornado-Like Vortex in Water
Authors: Hanari Toshihide , Sakakibara Jun
Published: March 2009

We investigated tornado-like vortex induced by a fan similar to Rushton turbine placed under the top surface of a cylindrical water tank. Experiment was performed under the condition of vortex Reynolds number being 3800 and Swirl ratio being 0.45. The three-component velocity fields in two adjacent cross-sections of the tornado-like vortex were measured by dual-plane stereoscopic PIV. Single vortex column was formed in the center of the tank. While the vortex core was dominated by an upward flow, abrupt velocity deficit at the center of vortex was observed in the axial component of mean velocity profile. Further more, instantaneous axial component of velocity at the vortex center has been fluctuated in time significantly. Such a fluctuation of the velocity was observed since the traveling wave of velocity or vorticity has been passing through. As an example of our data, temporal phase lag between the waves at the two planes indicated that the wave was propagated upstream with a speed of approximately 10% of the peak axial velocity at the vortex core. In order to clarify the mechanism of the fluctuation of the axial velocity component in the center of vortex, we focused on the axial pressure gradient along the vortex. Axial pressure gradient was found to be balanced with the substantive derivative of the measured axial velocity. Thus we conclude that the fluctuation of the axial velocity component at the center of the vortex was caused by local axial pressure gradient induced by the vorticity wave traveling along the vortex.
Visualization Study of Gas-Liquid Two-Phase Flow in a Hydrophobic Pipe
Authors: Kikuchi Takayoshi , Hazuku Tatsuya , Fukuhara Yutaka , Takamasa Tomoji , Hibiki Takashi
Published: March 2009

To evaluate the effect of pipe wall surface wettability on flow characteristics in a vertical upward gas-liquid two-phase flow, a visualization study was performed using an acrylic pipe and a hydrophobic pipe. Such basic flow characteristics as flow patterns, pressure drop and void fraction were investigated in these pipes. In the hydrophobic pipe, an inverted-churn flow regime was observed in a region where the churn flow regime was observed in the acrylic pipe, while a droplet flow regime was observed in the region where an annular flow regime was observed in the acrylic pipe. At a high gas flow rate, the average void fraction in the hydrophobic pipe was higher than in the acrylic pipe. The effect of surface wall wettability on frictional pressure loss was confirmed to be insignificant under the present experimental conditions.
Jet Fuel Cavitation in a Converging Diverging Nozzle
Authors: Davis Michael P. , Dunn Patrick F. , Thomas Flint O.
Published: March 2009

The focus of this research proposal is the experimental characterization of fuel cavitation in flow through a converging-diverging nozzle. Cavitation of fuel presents additional complexities (as compared to that in water) because fuel is a multi-component mixture. In any practical engineering environment, large quantities of solid microparticles are resident in the fuel. Gas nuclei trapped on these microparticles has been shown to enhance bubble production in water, and their effect on fuel cavitation is an issue that will be investigated. Measurements also will be made with cavitating water for comparison. A converging-diverging nozzle was chosen as the means for producing cavitation because its type of area constriction is similar to other flow devices such as valves and pumps. Cavitating C-D nozzle flows also have been modeled extensively in the literature. The data that will be acquired include axial pressure profiles, nozzle flow rate, high-speed images of the cavitating region, axial void fraction profiles, and axial velocity profiles. Pressure, velocity, and flow rate data will be used to determine the pressure ratios and limiting mass flow rates when the nozzle is choked. High speed images will be used to identify the structures present in the two-phase region (whether the gaseous voids are spherical bubbles or amorphous slugs. Axial void fraction data will provide information on gas evolution in the flow. Experimental data for cavitating nozzle flows are limited to water cases where bubble nucleation is not a primary source of the two-phase mixture. The proposed research hopes to provide detailed pressure, void-fraction, and velocity measurements for comparison with existing models. The main differences between fuel and water cavitation will be highlighted.