bluuebunny/crossref_metadata_2025 huggingface dataset:
Japanese guidelines for prevention of perioperative infections in urological field
Authors: Matsumoto Tetsuro , Kiyota Hiroshi , Matsukawa Masanori , Yasuda Mitsuru , Arakawa Soichi , Monden Koichi ,   Japanese Society of UTI Cooperative Study Group (Chairman; Tetsuro Matsumoto)
Published: September 2007

Abstract:  For urologists, it is very important to master surgical indications and surgical techniques. On the other hand, the knowledge of the prevention of perioperative infections and the improvement of surgical techniques should always be considered. Although the prevention of perioperative infections in each surgical field is a very important issue, the evidence and the number of guidelines are limited. Among them, the preparation of guidelines has progressed, especially in gastrointestinal surgery. The Center for Disease Control and Prevention (CDC) proposed guidelines for the prevention of surgical site infections, which have been used worldwide. In urology, the original guidelines were different from those of general surgery, due to many endourological procedures and urine exposure in the surgical field. The Japanese Society of UTI Cooperative Study Group has thus framed these guidelines supported by The Japanese Urological Association. The guidelines consist of the following nine techniques: open surgeries, laparoscopic surgeries, transurethral resection of bladder tumor, ureterorenoscope and transurethral lithotripsy, transurethral resection of the prostate, prostate biopsy, cystourethroscope, pediatric surgeries in the urological field, and extracorporeal shock wave lithotripsy and febrile neutropenia. These are the first guidelines for the prevention of perioperative infections in the urological field in Japan. Although most of these guidelines were made using reliable evidence, there are parts without enough evidence. Therefore, if new reliable data is reported, it will be necessary for these guidelines to be revised in the future.
18‐year recurrence‐free survival after extensive surgery for kidney cancer with atrial tumor thrombi
Authors: Nouh Mohammed Ahmed Abdel‐Muneem , Inui Masashi , Sugimoto Mikio , Kakehi Yoshiyuki , Yasukawa Akihiro
Published: September 2007

Abstract:  Tumor thrombus formation is a unique aspect of renal cell carcinoma with significant therapeutic and prognostic implications. The prognostic significance of cephalad extent of tumor thrombi to the right atrium remains controversial. Extended surgical removal, however, is the only way to expect survival. In 1989, a 40‐year‐old man was diagnosed with an advanced renal cell carcinoma (T3CN2M0) involving perinephric fat, hilar and para‐aortic lymph nodes and a tumor thrombus extending to the right atrium. He was treated with extensive surgical resection of the tumor and its lymphatic and vascular extensions. Interferon‐α injections were given for 2.5 years as an adjuvant immunotherapy. The patient was annually checked with abdominal ultrasound, chest X‐ray and computed tomography, but has manifested no local or distant metastasis for 18 years. To our knowledge, this is the first reported case of extensive surgery on advanced renal cell carcinoma with no evidence of recurrence for 18 years.
Non-Governmental Organizations as Motors of Change
Authors: Beyer Cornelia
Published: September 2007

On one hand, NGOs are seen as experts because of their proximity to the problems they address. They provide knowledge relevant to the solution of these problems and can bring this into the political process. They are able to increase the efficiency of global governance by participating in the policy-formation processes of international organizations. In this paper I will explain the role and functions of NGOs as described in the debate about their legitimacy and theorize – while applying Ernst Haas's theory of organizational learning – on the mechanisms likely to lead to their increasing integration into international institutions as well as the implications of this integration.
Electoral System Reform in Democracy's Grey Zone: Lessons from Putin's Russia
Authors: Moraski Bryon
Published: September 2007

Besides seat maximization, what factors motivate an incumbent regime in the grey zone between democracy and dictatorship to alter a relatively institutionalized parliamentary electoral system? To answer this question, this article seeks to uncover the rationale guiding the 2005 changes to Russia's electoral system. It presents evidence to suggest that the same strategies that allowed Russia's current party of power to use the existing electoral system to its advantage in the 2003 Duma election, threatened to spoil the fruits of that advantage in the years to come. Yet it also points out that moving from a mixed electoral system to a purely proportional system could be good for Russian democracy in the future. As a result, the work contends that seemingly authoritarian incumbents will promote reforms that aid the future cause of democracy when these same reforms serve their more immediate interests.
Being American (Politics of Identity – XI)
Authors: King Preston
Published: September 2007

‘Being American’ is a two-sided identity called ‘citizenship’. This involves a set (the state) and its members (citizens). The citizen (say Whitman) may be ‘fully’ American, just as some particular nation (say Native American, African, British, Jewish) may be so. But no one citizen (the patriot), or subset of citizens (perhaps the ethnic group), nor even the set of all citizens (past and present) reflects or symbolizes the whole of what ‘being American’ might mean. Nor can we reduce America's multitudes, and multitudinous practices, to one thickset/hotfoot Creed producing the sexy ‘American’/‘Un-American’ binary. Being American hangs upon a paramount constitutionalism that coolly reconciles, without melting, underlying identities. ‘Constitutionalism’ is informed by some abstract notion of justice, is grounded in mutual regard and equal liberty, and mere possession of ‘a constitution’ does not suffice to deliver it.
Somatic embryogenesis and multiple‐shoot formation from seed‐derived shoot apical meristems of rhodesgrass (Chloris gayana Kunth)
Authors: Gondo Takahiro , Matsumoto Jun , Yamakawa Kazutomi , Tsuruta Shin‐ichi , Ebina Masumi , Akashi Ryo
Published: September 2007

High‐frequencies of somatic embryogenesis and multiple‐shoot formation were achieved with seed‐derived shoot apical meristems of rhodesgrass (Chloris gayana Kunth). Shoot apices as initial explants were isolated from aseptically germinated seedlings, and cultured in vitro. Embryogenic calli and the multiple shoots were induced and maintained on MS basal medium with various combinations of 2,4‐dichlorophnoxyacetic acid (2,4‐D) and 6‐benzylaminopurine (BAP), the two most effective treatments being 2.0 mg L−1 2,4‐D and 0.1 mg L−1 2,4‐D + 2.0 mg L−1 BAP. These embryogenic calli and multiple‐shoot formations could be used as alternative regenerable target tissues for genetic transformation using particle bombardment of rhodesgrass.
Phytosociological study of steppe vegetation in east Kazakhstan
Authors: Cheng Yunxiang , Nakamura Toru
Published: September 2007

Following phytosociological methods, vegetation data were collected from 74 stands in the steppe area of east Kazakhstan, including Almaty, Pavlodar and Semipalatinsk Provinces. Detrended correspondence analysis (DCA) was used to extract the main compositional gradients of each of the 74 stands. In east Kazakhstan, four steppe vegetation communities were identified based on their species composition. The first ordination axis produced by DCA of species composition was associated with a decreasing Kira's warmth index (r = 0.84, P < 0.01) and an increasing Köppen P/E ratio (r = 0.70, P < 0.01). The second axis was associated with succession trends within the community as a result of different human activities. We identified a strong correlation with climatic factors, indicating that temperature and precipitation may influence the species composition of the east Kazakhstan steppe irrespective of human activities. Species composition, however, is affected by human disturbance, especially in such a severe environment where mean annual precipitation is below 300 mm in Pavlodar Province.
Evaluation of forest grazing as a management practice to utilize and control Miscanthus sinensis in a young tree plantation in southern Kyushu, Japan
Authors: Hirata Masahiko , Hasegawa Nobumi , Nogami Kangoro , Sonoda Tatsunobu
Published: September 2007

Miscanthus sinensis, a tall cespitose warm‐season perennial grass, occurs widely in tree plantations across Japan as a major weed. A 4‐year grazing trial was conducted in a young Chamaecyparis obtusa (an evergreen conifer) plantation in south‐western Japan, in an effort to evaluate forest grazing as a management practice to utilize and control M. sinensis and to deepen a mechanistic understanding of the responses of this grass to herbivory. The plantation was continuously stocked by Japanese Black cattle during the grazing season from May–November (July–November in the first year) at rates of 0.38–0.63 animals ha−1. M. sinensis was always the major species selected by animals, with most of the plants (80–90%) in the paddocks being defoliated during the grazing season. Reflecting these, M. sinensis plants declined with time under grazing, mainly in shoot number per tuft and partly in leaf appearance rate and the weight of the youngest fully expanded leaf, leading to a drastic decrease in production of leaves (laminae) as a photosynthetic organ and a main feed component for animals. Animals did little fatal damage to C. obtusa trees. Performance of animals was acceptable for cows that had experienced forest grazing in preceding years, but needed improvement for inexperienced heifers and calves. The results demonstrate the potential value of cattle grazing in utilizing and controlling M. sinensis in young tree plantations, which enables multifunctional land use linking forest and animal industries. Further studies are necessary to explore the optimum grazing intensity that balances effective control and extended utilization of the grass.
Cooperation and Communication in the 2nd Year of Life
Authors: Tomasello Michael
Published: September 2007

ABSTRACT—
Although primates have evolved complex cognitive skills and strategies for competing with others in their social group, only humans have developed complex cognitive skills and motivations for collaborating with one another in joint endeavors. This cooperative dimension of human cognition emerges most clearly around the first birthday as children begin to collaborate and communicate with joint intentions and joint attention. This collaboration is also grounded in social motivations for helping and sharing with others that are unique to humans. In using the skills of shared intentionality that underlie these cooperative interactions, 1‐year‐olds come to create perspectival cognitive representations.
A Neurobiological Perspective on Early Human Deprivation
Authors: Nelson Charles A.
Published: September 2007

ABSTRACT—
The number of children who are abandoned or orphaned around the world is rapidly increasing owing to war, AIDS, and poverty. Many of these children are placed in institutional settings for lack of individual or societal resources or because of long‐standing cultural traditions. It has been known for over half a century that rearing children in institutional care characterized by profound sensory, cognitive, linguistic, and psychosocial deprivation can be deleterious to their development. This article examines the neural mechanisms that likely underlie the maldevelopment many institutionalized children experience.
How Marginal Deviations Sometimes Grow Into Serious Aggression
Authors: Caprara Gian Vittorio , Dodge Kenneth A. , Pastorelli Concetta , Zelli Arnaldo
Published: September 2007

ABSTRACT—
We offer a theory of marginal deviations that articulates the processes through which initial behavior that is only slightly deviant from the norm gets transformed into more serious antisocial outcomes. We present evidence that, of the one third of the population that is marginally deviant, about one fourth (or 8% of the total population) becomes seriously deviant over time. Hypothesized factors in this transformation involve the child actor, peer observer–judges, and social transactions between them in processes that derive from self‐fulfilling prophecies and dynamic systems theory. Hypotheses and studies are proposed to address the circumstances and processes that determine whether a marginal deviation will be bought back to the norm (through assimilation and attenuation) or accelerated to severe deviance (through accommodation and amplification).
Effective Educational Programs for Young Children: What We Need to Know
Authors: Takanishi Ruby , Bogard Kimber L.
Published: September 2007

ABSTRACT—
Policymakers and researchers have shared interests in educational programs for young children. Policymakers see these programs as a potential means of narrowing the persistent gaps in achievement evident in many children entering kindergarten. Researchers see their role as one of assessing the effectiveness of various programs so that policymakers can make informed decisions. This article provides an overview of what is currently known and what needs to be determined about the factors that contribute to positive outcomes from early education programs. New prospective longitudinal studies are needed, as well as secondary analyses of recent large‐scale longitudinal studies, which can inform issues of program design and impact. Five gaps in knowledge about effective programs are identified: program design for an increasingly ethnically diverse group of young children, including those of immigrants; connecting teaching and learning processes to child outcomes; understanding a broad range of child outcomes based on developmental science; bringing multiple disciplinary perspectives to bear on what constitutes effective early education programs; and continuing to address how research and practice can be mutually beneficial.
Are All IQ Scores Created Equal? The Differential Costs of IQ Cutoff Scores for At‐Risk Children
Authors: Kanaya Tomoe , Ceci Stephen J.
Published: September 2007

ABSTRACT—
The IQ cutoff score of 70 used for the diagnosis of mental retardation has repercussions throughout America, influencing educational, social, and legal decision making. Because of the Flynn effect and changing IQ norms, however, IQ scores are rising and falling over time, independent of actual cognitive gains or losses. These fluctuations, combined with the use of the cutoff score, result in substantial misallocations of financial, educational, and social resources for children of all IQ levels but especially for those at risk for academic failure. Such far‐reaching and grave implications call into question the use of IQ cutoff scores in educational and legal policies and underscore the importance for researchers to collect data in real‐world settings to understand and appreciate the issues that surround the application of developmental theory.
Stalking the Roving IQ Score Cutoff: A Commentary on Kanaya and Ceci (2007)
Authors: Widaman Keith F.
Published: September 2007

ABSTRACT—

T. Kanaya and S. J. Ceci (2007) reviewed research on perturbations in rates of mental retardation diagnoses associated with the Flynn effect. They argued that their results call into question the use of IQ cutoff scores in high‐stakes decisions but acknowledged that no viable alternatives to cutoff scores could be strongly endorsed. Further, Kanaya and Ceci argued that Flynn‐effect adjustments to IQ scores were problematic, a position that should be open to debate. Further research and clear recommendations for practice are certainly needed on this important problem.
Mental Retardation Diagnosis and the Flynn Effect: General Intelligence, Adaptive Behavior, and Context
Authors: Kanaya Tomoe , Ceci Stephen J.
Published: September 2007

ABSTRACT—
Due to the Flynn effect and the IQ cutoff score required for the diagnosis of mental retardation (MR), educational and social policies created to reduce inequities faced by at‐risk children in theory may actually perpetuate them in practice. We argue for the importance of considering IQ, adaptive behavior, and context when diagnosing MR and conclude by recommending that more research is needed to determine individual differences in the Flynn effect among children who are at risk of academic failure and therefore, most vulnerable to such differences.
Development and public release of a comprehensive hepatitis virus database
Authors: Shin‐i Tadasu , Tanaka Yasuhito , Tateno Yoshio , Mizokami Masashi
Published: September 2007

Aim:  Currently, approximately 44 000 hepatitis C virus (HCV), 11 000 hepatitis B virus (HBV), and 1600 hepatitis E virus (HEV) sequences are available at the International Nucleotide Sequence Database Collaboration (INSDC, previously known as DDBJ/EMBL/GenBank), and the number of these virus sequences is growing rapidly. However, since INDSC is not specialized to hepatitis viruses, it is difficult to retrieve information of virological or clinical interests from it. Thus, it is quite worthwhile to construct a specialized database for the hepatitis virus sequences and to make it accessible to researchers worldwide.

Methods:  We developed a WWW‐based database hepatitis virus database (HVDB), which contains all the HCV, HBV, and HEV sequences available at INSDC. In the HVDB, all piece sequences obtained from INSDC are arranged to the genomesequence of each virus. Also given in the database are the phylogenetic relationships of each locus on the genome among variants for each virus.

Results:  Users of the database can easily retrieve entries (sequences with annotations) of the specific genotype by referring to the phylogenetic relationships or those of specific loci by referring to the genome map information. HVDB provides users with a tool for phylogenetic analysis that can be used in combination with the data retrieval tools.

Conclusion:  The latest release is publicly accessible at the HVDB website: http://s2as02.genes.nig.ac.jp.
Prevalence of hepatitis B virus infection in Japanese patients with HIV
Authors: Koike Kazuhiko , Kikuchi Yoshimi , Kato Michio , Takamatsu Junki , Shintani Yoshizumi , Tsutsumi Takeya , Fujie Hajime , Miyoshi Hideyuki , Moriya Kyoji , Yotsuyanagi Hiroshi
Published: September 2007

Patients with HIV infection are frequently infected with hepatitis viruses, which are presently the major cause of mortality in HIV‐infected patients after the widespread use of highly active antiretrovirus therapy. We previously reported that approximately 20% of HIV‐positive Japanese patients were also infected with hepatitis C virus (HCV). Hepatitis B virus (HBV) infection may also be an impediment to a good course of treatment for HIV‐infected patients, because of recurrent liver injuries and a common effectiveness of some anti‐HIV drugs on HBV replication. However, the status of co‐infection with HIV and HBV in Japan is unclear. We conducted a nationwide survey to determine the prevalence of HIV–HBV co‐infection by distributing a questionnaire to the hospitals belonging to the HIV/AIDS Network of Japan. Among the 5998patients reported to be HIV positive, 377 (6.4%) were positive for the hepatitis B surface antigen. Homosexual men accounted for two‐thirds (70.8%) of the HIV–HBV co‐infected patients, distinct from HIV–HCV co‐infection in Japan in which most of the HIV–HCV co‐infected patients were recipients of blood products. One‐third of HIV–HBV co‐infected patients had elevated serum alanine aminotransferase levels at least once during the 1‐year observation period. In conclusion, some HIV‐infected Japanese patients also have HBV infection and liver disease. A detailed analysis of the progression and activity of liver disease in co‐infected patients is needed.
Characteristics of the Hydrodynamic Coefficient for Flow of a Steam-Water Mixture in a Pebble Bed
Authors: Avdeev Alexandr A. , Balunov Boris F. , Rybin Rostislav A. , Soviev Ruslan I. , Zudin Yuri B.
Published: September 2007

Pressure loss for flow of a steam-water mixture in a pebble bed is experimentally investigated (the first stage of the study was described in Avdeev, et al., 2003 [High Temp., 41, pp. 371–383]). The measurements of the care performed within the wide range of regime parameters: pressures of 0.9-15.6MPa, mass-flow rates of 107-770kg∕(m2s) and steam quality of 0–0.49. The experimental data for the pressure loss of single-phase air and water flows were used as reference data. The final results are represented in the form of the ratio of the pressure loss for the steam-water flow to that for the single-phase water flow at identical mass-flow rates.
Experimental and Theoretical Nonlinear Dynamic Response of Intact and Cracked Bone-Like Specimens With Various Boundary Conditions
Authors: Ogam Erick , Wirgin Armand , Fellah Z. E. A. , Xu Yongzhi
Published: September 2007

The potentiality of employing nonlinear vibrations as a method for the detection of osteoporosis in human bones is assessed. We show that if the boundary conditions (BC), relative to the connection of the specimen to its surroundings, are not taken into account, the method is apparently unable to differentiate between defects (whose detection is the purpose of the method) and nonrelevant features (related to the boundary conditions). A simple nonlinear vibration experiment is described which employs piezoelectric transducers (PZT) and two idealized long bones in the form of nominally-identical drinking glasses, one intact, but in friction contact with a support, and the second cracked, but freely-suspended in air. The nonlinear dynamics of these specimens is described by the Duffing oscillator model. The nonlinear parameters recovered from vibration data coupled to the linear phenomena of mode splitting and shifting of resonance frequencies, show that, despite the similar soft spring behavior of the two dynamic systems, a crack is distinguishable from a contact friction BC. The frequency response of the intact glass with contact friction BC is modeled using a direct steady state finite element simulation with contact friction.
Synchronous Position Recovery Control for Flexible Rotors in Contact with Auxiliary Bearings
Authors: Schlotter Michael , Keogh Patrick S.
Published: September 2007

This paper details a methology for the active recovery of contact free levitation of a rotor from a state of persistent contact with auxiliary bearings. An analytical method to describe contact dynamics of flexible rotors is presented. It shows that synchronous unbalance forces can cause a rotor to adopt stable contact modes, which are characterized by periodic motion and a fixed contact point in a rotating frame of reference. Based on these observations, a recovery strategy is developed to return the rotor to a contact free state. Compensation forces may be applied by magnetic bearings to reduce the effective synchronous forcing which is driving the contact, so that the rotor can progress to a contact free orbit. It is shown that even in the presence of highly nonlinear contact dynamic effects, a linear finite element rotor model can be used to calculate appropriate influence coefficients. The contact recovery procedure is successfully verified by simulations and measurements on a flexible rotor test facility. Allowable bounds on the phase of the synchronous recovery forces are investigated and limitations of the method are discussed.
Stochastic Heat Transfer in Fins and Transient Cooling Using Polynomial Chaos and Wick Products
Authors: Emery A. F. , Bardot D.
Published: September 2007

Stochastic heat transfer problems are often solved using a perturbation approach that yields estimates of mean values and standard deviations for properties and boundary conditions that are random variables. Methods based on polynomial chaos and Wick products can be used when the randomness is a random field or white noise to describe specific realizations and to determine the statistics of the response. Polynomial chaos is best suited for problems in which the properties are strongly correlated, while the Wick product approach is most effective for variables containing white noise components. A transient lumped capacitance cooling problem and a one-dimensional fin are analyzed by both methods to demonstrate their usefulness.
Forced
Convective Heat Transfer in Parallel Flow Multilayer
Microchannels
Authors: Saidi M.
H. , Khiabani Reza
H.
Published: September 2007

In this paper, the effect of increasing the number of layers on improving the thermal performance of microchannel heat sinks is studied. In this way, both numerical and analytical methods are utilized. The analytical method is based on the porous medium assumption. Here, the modified Darcy equation and the energy balance equations are used. The method has led to an analytical expression presenting the average dimensionless temperature field in the multilayer microchannel heat sink. The effects of different parameters such as aspect ratio, porosity, channel width, and the solid properties on the thermal resistance are described. The results for single layer and multilayer heat sinks are compared to show the effectiveness of using multilayer microchannels.
Laminar Mixed Convection in the Entrance Region of Horizontal Semicircular Ducts With the Flat Wall at the Top
Authors: El. Hasadi Y. M. F. , Busedra A. A. , Rustum I. M.
Published: September 2007

Laminar mixed convection in the entrance region for horizontal semicircular ducts with the flat wall on top is investigated theoretically. The governing momentum and energy equations are solved numerically using a marching technique with the finite control volume approach following the SIMPLER algorithm. Results are obtained for the thermal boundary conditions of uniform heat input axially with uniform wall temperature circumferentially at any cross section (H1 boundary condition) with Pr=0.7 and a wide range of Grashof numbers. These results include the velocity and temperature distributions at different axial locations, axial distribution of local Nusselt number, and local average wall friction factor. It is found that Nusselt number values are close to the forced convection values near the entrance region and then decrease to a minimum as the distance from the entrance increases and then rise due to the effect of free convection before reaching constant value (fully developed). As the Grashof number increases the Nusselt number and the average wall friction factor increase in both developing and fully developed regions and the location of the onset of the secondary flow moves upstream.
Heat Exchanger Efficiency
Authors: Fakheri Ahmad
Published: September 2007

This paper provides the solution to the problem of defining thermal efficiency for heat exchangers based on the second law of thermodynamics. It is shown that corresponding to each actual heat exchanger, there is an ideal heat exchanger that is a balanced counter-flow heat exchanger. The ideal heat exchanger has the same UA, the same arithmetic mean temperature difference, and the same cold to hot fluid inlet temperature ratio. The ideal heat exchanger’s heat capacity rates are equal to the minimum heat capacity rate of the actual heat exchanger. The ideal heat exchanger transfers the maximum amount of heat, equal to the product of UA and arithmetic mean temperature difference, and generates the minimum amount of entropy, making it the most efficient and least irreversible heat exchanger. The heat exchanger efficiency is defined as the ratio of the heat transferred in the actual heat exchanger to the heat that would be transferred in the ideal heat exchanger. The concept of heat exchanger efficiency provides a new way for the design and analysis of heat exchangers and heat exchanger networks.
Natural Convection Heat Transfer From Horizontal Rectangular Ducts
Authors: Ali Mohamed E.
Published: September 2007

Experimental investigations have been reported on steady state natural convection from the outer surface of horizontal ducts in air. Five ducts have been used with aspect ratios (Γ=duct height/duct width) of 2, 1, and 0.5. The ducts are heated using internal constant heat flux heating elements. The temperatures along the surface and peripheral directions of the duct wall are measured. Longitudinal (circumference averaged) heat transfer coefficients along the side of each duct are obtained for laminar and transition regimes of natural convection heat transfer. Total overall averaged heat transfer coefficients are also obtained. Longitudinal (circumference averaged) Nusselt numbers are evaluated and correlated using the modified Rayleigh numbers for transition regime using the axial distance as a characteristic length. Furthermore, total overall averaged Nusselt numbers are correlated with the modified Rayleigh numbers, the aspect ratio, and area ratio for the laminar and transition regimes. The longitudinal or total averaged heat transfer coefficients are observed to decrease in the laminar region and to increase in the transition region. Laminar regimes are obtained only at very small heat fluxes, otherwise, transitions are observed.
Temperature-Dependent Viscosity and Viscous Dissipation Effects in Simultaneously Developing Flows in Microchannels With Convective Boundary Conditions
Authors: Nonino C. , Del Giudice S. , Savino S.
Published: September 2007

The effects of viscous dissipation and temperature dependent viscosity in simultaneously developing laminar flows of liquids in straight microchannels are studied with reference to convective boundary conditions. Two different geometries, namely the circular tube and the parallel plate channel, are considered. Viscosity is assumed to vary with temperature according to an exponential relation, while the other fluid properties are held constant. A finite element procedure, based on a projection algorithm, is employed for the step-by-step solution of the parabolized momentum and energy equations. Axial distributions of the local overall Nusselt number and of the apparent Fanning friction factor are presented with reference to both heating and cooling conditions for two different values of the Biot number. Examples of radial temperature profiles at different axial locations and of axial distributions of centerline velocity and temperature are also shown.
Laser Transmission Welding of a Lap-Joint: Thermal Imaging Observations and three–dimensional Finite Element Modeling
Authors: Mayboudi L. S. , Birk A. M. , Zak G. , Bates P. J.
Published: September 2007

Laser transmission welding (LTW) is a relatively new technology for joining plastic parts. This paper presents a three-dimensional (3D) transient thermal model of LTW solved with the finite element method. A lap-joint geometry was modeled for unreinforced polyamide (PA) 6 specimens. This thermal model addressed the heating and cooling stages in a laser welding process with a stationary laser beam. This paper compares the temperature distribution of a lap-joint geometry exposed to a stationary diode laser beam, obtained from 3D thermal modeling with thermal imaging observations. It is shown that the thermal model is capable of accurately predicting the temperature distribution when laser beam scattering during transmission through the polymer is included in the model. The weld dimensions obtained from the model have been compared with the experimental data and are in good agreement.
A Numerical Study of Flow and Heat Transfer Enhancement Using an Array of Delta-Winglet Vortex Generators in a Fin-and-Tube Heat Exchanger
Authors: Joardar A. , Jacobi A. M.
Published: September 2007

This work is aimed at assessing the potential of winglet-type vortex generator (VG) “arrays” for multirow inline-tube heat exchangers with an emphasis on providing fundamental understanding of the relation between local flow behavior and heat transfer enhancement mechanisms. Three different winglet configurations in common-flow-up arrangement are analyzed in the seven-row compact fin-and-tube heat exchanger: (a) single–VG pair; (b) a 3VG-inline array (alternating tube row); and (c) a 3VG-staggered array. The numerical study involves three-dimensional time-dependent modeling of unsteady laminar flow (330⩽Re⩽850) and conjugate heat transfer in the computational domain, which is set up to model the entire fin length in the air flow direction. It was found that the impingement of winglet redirected flow on the downstream tube is an important heat transfer augmentation mechanism for the common-flow-up arrangement of vortex generators in the inline-tube geometry. At Re=850 with a constant tube-wall temperature, the 3VG-inline-array configuration achieves enhancements up to 32% in total heat flux and 74% in j factor over the baseline case, with an associated pressure-drop increase of about 41%. The numerical results for the integral heat transfer quantities agree well with the available experimental measurements.
Local Heat Transfer Coefficients Induced by Piezoelectrically Actuated Vibrating Cantilevers
Authors: Kimber Mark , Garimella Suresh V. , Raman Arvind
Published: September 2007

Piezoelectric fans have been shown to provide substantial enhancements in heat transfer over natural convection while consuming very little power. These devices consist of a piezoelectric material attached to a flexible cantilever beam. When driven at resonance, large oscillations at the cantilever tip cause fluid motion, which in turn results in improved heat transfer rates. In this study, the local heat transfer coefficients induced by piezoelectric fans are determined experimentally for a fan vibrating close to an electrically heated stainless steel foil, and the entire temperature field is observed by means of an infrared camera. Four vibration amplitudes ranging from 6.35to10mm are considered, with the distance from the heat source to the fan tip chosen to vary from 0.01 to 2.0 times the amplitude. The two-dimensional contours of the local heat transfer coefficient transition from a lobed shape at small gaps to an almost circular shape at intermediate gaps. At larger gaps, the heat transfer coefficient distribution becomes elliptical in shape. Correlations developed with appropriate Reynolds and Nusselt number definitions describe the area-averaged thermal performance with a maximum error of less than 12%.
Developing Turbulent Forced Convection in Two-Dimensional Duct
Authors: Chen Y. T. , Nie J. H. , Armaly B. F. , Hsieh H. T. , Boehm R. F.
Published: September 2007

Developing turbulent forced convection flow in a two-dimensional duct is simulated for Reynolds numbers ranging from 4560 to 12,000. Simultaneously developing velocity and temperature distributions are reported by treating the inlet flow as isothermal with uniform velocity profile. The walls are supplied with uniform heat flux. Distributions of the streamwise and the transverse velocity components exhibit a maximum near the walls, but not at the center of the duct, in the developing region of the flow. The friction coefficient and the Nusselt number do not reach the fully developed values monotonously, and a minimum in their distributions appears in the developing region. Some results are compared with the available data, and very favorable comparisons are obtained.
Discussion: “Second Law Analysis of Laminar Viscous Flow Through a Duct Subjected to Constant Wall Temperature” (Sahin, A. Z., 1998, ASME J. Heat Transfer, 120, pp. 76–83)
Authors: Awad M. M.
Published: September 2007

In the paper Sahin, A. Z., 1998, “Second Law Analysis of Laminar Viscous Flow Through a Duct Subjected to Constant Wall Temperature” ASME J. Heat Transfer, 120(1), pp. 76–83, there are many errors in equations, values, etc. The errors will be summarized below.
Random Response Relationships to Transfer Function and State-Space Properties
Authors: Redfield Robin C.
Published: September 2007

Output variables of dynamic systems subject to random inputs are often quantified by mean-square calculations. Computationally for linear systems, these typically involve integration of the output spectral density over frequency. Numerically, this is a straightforward task and, analytically, methods exist to find mean-square values as functions of transfer function (frequency response) coefficients. These formulations offer analytical relationships between system parameters and mean-square response. This paper develops further analytical relationships in calculating mean-square values as functions of transfer function and state-space properties. Specifically, mean-square response is formulated from (i) system pole-zero locations, (ii) as a spectral decomposition, and (iii) in terms of a system matrix transfer function. Direct, closed-form relationships between response and these properties are afforded. These new analytical representations of the mean-square calculation can provide significant insight into dynamic system response and optimal design/tuning of dynamic systems.
New Methods for Nonlinear Damping Identification of Damping Alloy
Authors: Wu Ziying , Liu Hongzhao , Liu Lilan , Yuan Daning
Published: September 2007

This paper presents two methods for the identification of nonlinear internal damping of alloy. One is the moving autoregressive model (MARM) method, and the other is the time-varying autoregressive model (TVARM) method. These procedures have been successfully implemented on two numerical examples. Comparison between simulation results demonstrates that the computation accuracy of the TVARM method is higher than that of the MARM method. In the experiments, the internal damping properties of the alloy Al-33Zn-6Si are researched, employing the rectangle beam with a nonuniform stress field and the trapezoid beam with a quasi-uniform stress field, respectively. Experimental results show that the internal damping of the alloy increases with the increasing strain and appears a nonlinear behavior. Moreover, the damping values of the trapezoid beam are relatively higher than those of the rectangle beam. Compared to the MARM method, the TVARM method can give a better description of nonlinear damping because the relation curve of loss factor versus strain obtained by the TVARM method is smoother than that obtained by the MARM method.
Frame Flexibility Effects on Engine Mount Optimization for Vibration Isolation in Motorcycles
Authors: Kaul Sudhir , Dhingra Anoop K. , Hunter Timothy G.
Published: September 2007

This paper examines the influence of frame flexibility on the optimization of an engine mounting system for enhanced vibration isolation in motorcycles. A theoretical model is developed to represent the structural dynamics of an engine mount system in motorcycles. The model consists of the power-train assembly, modeled as a six-degree-of-freedom (DOF) rigid body; the swing arm assembly, connected to the power-train through a coupler shaft assembly; and the frame, connected to the power-train by elastomeric mounts and to the swing-arm through the rear suspension. Two models of the flexible frame are developed for analysis. The first model uses an equivalent stiffness matrix of the frame, derived from its finite element model, in terms of the nodes connecting the frame to the other subsystems. The second model is based on a dynamic model of the frame as well as the swing arm derived from their respective finite element models. The optimization procedure minimizes the load transmitted to the frame while constraining the engine displacement due to imposed loads within prescribed limits. The mount stiffnesses, locations and orientations are used as design variables. Examples are presented to demonstrate the influence of frame flexibility on the force transmitted to the frame.
Pole Placement Techniques for Active Vibration Control of Smart Structures: A Feasibility Study
Authors: Kumar Rajiv , Khan Moinuddin
Published: September 2007

It is well known that there is degradation in the performance of a fixed parameter controller when the system parameters are subjected to a change. Conventional controllers can become even unstable, with these parametric uncertainties. This problem can be avoided by using robust and adaptive control design techniques. However, to obtain robust performance, it is desirable that the closed-loop poles of the perturbed structural system remain at prespecified locations for a range of system parameters. With the aim to obtain robust performance by manipulating the closed loop poles of the perturbed system, feasibility of the pole placement based controller design techniques is checked for active vibration control applications. The controllers based on the adaptive and robust pole placement method are implemented on smart structures. It was observed that the adaptive pole placement controllers are noise tolerant, but require high actuator voltages to maintain stability. However, robust pole placement controllers require comparatively small amplitude of control voltage to maintain stability, but are noise sensitive. It was realized that by using these techniques, robust stability and performance can be obtained for a moderate range of parametric uncertainties. However, the position of closed-loop poles should be judiciously chosen for both the control design strategies to maintain stability.
Nonstationary Vibration of a Fully Flexible Parallel Kinematic Machine
Authors: Zhou Zili , Mechefske Chris K. , Xi Fengfeng
Published: September 2007

This paper studies the problem of the nonstationary vibration of a fully flexible parallel kinematic machine (PKM) that has flexibilities both in links and in joints. In the stationary case, the PKM was treated as a varying structure and the natural frequencies and mode shapes changed with the changes in the PKM configuration, without consideration of the PKM nominal motion. In the nonstationary case as studied in this paper, the nominal motion is included to investigate how it would affect the natural frequencies and mode shapes. To do so, a nonstationary model is developed using the elasto-dynamics method. First, a kinematic model is built based on rigid links and ideal joints, which is used to solve the PKM nominal motion. Second, the kinetic model is developed considering the flexibilities in the links and joints. In this case, the vibration equations would contain the Coriolis and gyroscopic damping matrix and the tangential and normal stiffening matrix, which are the terms resulting from the nominal motion. The instantaneous eigensolutions are obtained from the nonstationary eigenequations. The results show that (i) the slider velocity affects the instantaneous natural frequencies more than the slider acceleration; and (ii) the nominal motion has an effect on the system eigencharacteristics (e.g., the nonstationary frequencies can be higher or lower than the stationary ones) but the effect is small in an absolute amount (within 2.1Hz in natural frequencies presented at set nominal motions of the studied PKM prototype). This is because the extra inertial force from the nominal motion is always much smaller than the stiffness force in the system bodies as long as the bodies are made of hard material. The method presented is more convenient to use for the multibody system with flexible joints than other methods.
An Experimentally Verified Model of a Membrane Mirror Strip Actuated Using a Piezoelectric Bimorph
Authors: Renno Jamil M. , Inman Daniel J.
Published: September 2007

The behavior of a membrane mirror strip actuated using a piezoelectric bimorph is treated. An improved model for the transverse vibration is presented. The model accounts for the changes in physical properties of the membrane strip at the location of the piezoelectric bimorph. The membrane strip is modeled as a pinned-pinned beam under tension and the finite element method (FEM) is used to represent the system mathematically. The beam under tension assumption allows accounting for the traveling wave effect experienced by a membrane strip and the added flexural rigidity induced by the piezoelectric bimorph. Additionally, the structural and air damping effects are included in the model. An experimental setup is built to verify the proposed model. The frequency response obtained from the proposed model is shown to be in agreement with conducted experiments. Furthermore, the importance of including local mass and stiffness effects is demonstrated.
Permeability and Inertial Coefficients of Porous Media for Air Bearing Feeding Systems
Authors: Belforte G. , Raparelli T. , Viktorov V. , Trivella A.
Published: September 2007

In porous resistances, Darcy’s law provides a good approximation of mass flow rate when the differences between upstream and downstream pressures are sufficiently small. In this range, the mass flow rates are proportional to the porous resistance’s permeability. For gas bearings, the pressure difference is normally higher, and it is known experimentally that the mass flow rates are lower than would result from Darcy’s law. Forchheimer’s law adds an inertial term to Darcy’s law and, when an appropriate coefficient is selected for this term, provides a good approximation of flow rates for the same applications even with the highest pressure differences. This paper presents an experimental and theoretical investigation of porous resistances used in gas bearing and thrust pad supply systems. The porous resistances considered in the investigation were made by sintering bronze powders with different grain sizes to produce cylindrical inserts that can be installed in bearing supply devices. The paper describes the test setup and experimental results obtained for: (i) mass flow rate through single porous resistances at different upstream and downstream pressures and (ii) mass flow rate and pressure distribution on a pneumatic pad featuring the same porous resistances. The theoretical permeability of the chosen porous resistances was calculated, and the results from setup (i) were then used to obtain experimental permeability and to determine the inertial coefficients. The results, which are expressed as a function of the Reynolds number, confirmed the validity of using Forchheimer’s law. The mass flow rates from setup (ii) were compared to those from setup (i) at the same pressure differentials across the resistance.
Development of Theoretical Contact Width Formulas and a Numerical Model for Curved Rough Surfaces
Authors: Wang Shao
Published: September 2007

The apparent contact area of curved rough surfaces can be larger than that predicted by the Hertz theory due to asperity interaction outside the Hertzian region. In the present study, simple theoretical formulas for the contact semi-width and radius for Gaussian and truncated Gaussian height distributions were derived, and a numerical contact model was developed based on a general power-law relationship between the local apparent pressure and real-to-apparent contact ratio. Numerical results of the contact semi-width agree well with the prediction of the formula. The apparent contact region becomes increasingly larger than the Hertzian region as a dimensionless roughness parameter increases or as a dimensionless load parameter decreases. The ratio of the contact semi-width to the Hertzian semi-width and the apparent pressure distribution are completely determined by a dimensionless contact parameter and the dimensionless roughness parameter, which are both independent of the instrument resolution, thus providing a long awaited solution to the problem of instrument dependency in a traditional theory. An application to fractal-regular surfaces indicates that the influence of the fractal dimension on the contact behavior is due to its effects on both the area-load coefficient and the load exponent.