bluuebunny/crossref_metadata_2025 huggingface dataset:
Health Status of Incarcerated Adolescents: Implications for Juvenile Justice Decision Making
Authors: MORRIS ROBERT E.
Published: July 2009

Adolescents arriving in detention often bring with them significant medical, dental, and psychological problems. These issues have important implications for courts that must decide the best disposition for offending youths. Appropriate treatment benefits the individual by enhancing his/her well‐being and improving his/her chances of successful rehabilitation. Society also benefits by avoiding the higher cost of caring for neglected conditions later in life. A comprehensive health care program for detention facilities involves establishing standardized procedures that address both common adolescent problems plus those more peculiar to detainees. Health care professionals working in a correctional setting have unique duties such as clearing youths for boot camp, monitoring injuries, dealing with resistant patients, monitoring for safe activities, and planning aftercare for youths who may face impediments to accessing care such as poor motivation and poverty. Research concerning issues specific to the needs of incarcerated youths remains infrequent and should be undertaken by health care providers. This article provides an overview of medical issues confronting juvenile offenders that should be considered when a juvenile becomes involved in the juvenile justice system.
Juvenile Accountability and the Specific Deterrent Effects of Short‐Term Confinement
Authors: GREEN GARY S. , CARLSON PETER M. , COLVIN ROBERT E.
Published: July 2009

To assess the specific deterrent (“teaching a lesson”) and normative validation effects of confinement, the intake histories of a random sample of youths (n=87) confined in a local detention facility were analyzed to determine if the amount of the immediately previous confinement or the total amount of confinement experienced affects the amount of time until the next system intake. No statistically significant relationships were found for any of the intakes, up through eight intakes. The findings, however, demonstrate that a non‐graduated approach to imposition of punishment that did not adequately emphasize individual accountability was not an effective deterrent for the more recalcitrant youths included in this study. Theoretical and policy implications of the findings are discussed.
Zero to Three: Critical Issues for the Juvenile and Family Court
Authors: COHEN JULIE , YOUCHA VICTORIA
Published: July 2009

Infants are the fastest growing population in foster care. Without intervention they are at great risk of poor developmental outcomes. Juvenile and family courts have a unique opportunity to make a positive difference in the lives of the babies in their care. This article outlines six critical issues that impact the development of very young children in the child welfare system and recommends strategies that juvenile and family courts can use to address the needs of this most vulnerable population.
Building Bridges for Babies in Foster Care: The Babies Can't Wait Initiative
Authors: DICKER SHERYL , GORDON ELYSA
Published: July 2009

In 2001, the New York State Permanent Judicial Commission on Justice for Children, chaired by New York State's Chief Judge Judith Kaye, developed the Babies Can't Wait Initiative to maximize the well‐being and permanency prospects of infants in foster care. This court‐based innovation became a path to healthy development for babies in foster care, a bridge to unprecedented collaboration among the New York City Family Court, child welfare system, and service providers and merged knowledge about child development with court and child welfare practice. This article tells the story of the Babies Can't Wait Initiative—its creation, implementation, successes, and lessons.
Questions Every Judge and Lawyer Should Ask About Infants and Toddlers in the Child Welfare System
Authors: OSOFSKY JOY D. , MAZE CANDICE L. , LEDERMAN JUDGE CINDY S. , GRACE MARTHA P. , DICKER SHERYL
Published: July 2009

We need to change the culture in our courts. Instead of ignoring the special needs of babies and toddlers, we need to recognize that abused and neglected children are at risk for developing negative sequelae as a result of their maltreatment. The science of early development is unequivocal that early intervention can be effective. The following questions were developed as a guide for lawyers, judges, and child advocates in the child welfare system as a first step toward advocacy and intervention for young children. Armed with the questions, the scientific reasons they need to be asked, and the research that provides support, we recommend that these questions be used as a tool and be asked over and over until the needs of maltreated infants and babies are addressed. It is our legal obligation under the Adoption and Safe Families Act of 1997, and it is our moral responsibility to these young children.
Pathways from Traumatic Child Victimization to Delinquency: Implications for Juvenile and Permanency Court Proceedings and Decisions
Authors: FORD JULIAN D. , CHAPMAN JOHN , MACK JUDGE MICHAEL , PEARSON GERALDINE
Published: July 2009

Research studies and observations by mental health and judicial professionals suggest that childhood traumatic victimization may contribute to the development of juvenile delinquency. Based on this evidence, we describe a chronological pathway that runs from: (a) early childhood victimization, to (b) escalating dysregulation of emotion and social information processing (“survival coping,” which takes the form of depression, anxiety, social isolation, peer rejection, and conflicted relationships), to (c) severe and persistent problems with oppositional‐defiance and overt or covert aggression compounded by post‐traumatic reactivity and hypervigilance (“victim coping”). A case vignette is provided, and implications for judicial review and decisions are discussed.
Juvenile Diversion: An Outcome Study of the Hamilton County, Ohio Unofficial Juvenile Community Courts
Authors: BECK VICTORIA SIMPSON , RAMSEY ROBERT J. , LIPPS JUDGE THOMAS R. , TRAVIS LAWRENCE F.
Published: July 2009

An overall goal of juvenile diversion programs is to deinstitutionalize and decriminalize minor types of delinquent behavior by minimizing penetration into the justice system. Proponents of juvenile diversion programs have argued that diversion programs provide additional services to youths; and, since diversion programs are less stigmatizing, they may restrain the escalation of delinquency. Nonetheless, many diversion programs are never analyzed. This study describes and presents outcome data from a diversion program in Hamilton County, Ohio.
Asking the Right Questions: Utilizing a Judicial Checklist to Track the Educational Success of Youth in Foster Care
Authors: WEISS SUSAN A. , STAUB DEBBIE , CAMPBELL PAULA , GATOWSKI SOPHIA I. , LITCHFIELD MELISSA
Published: July 2009

Asking about the educational objectives for children in foster care has not been a priority in most juvenile and family courts. Research has shown that compared to the general school population, children in foster care have lower grade point averages, change schools more frequently, earn fewer credits toward graduation, and are more likely to be placed in special education programs. In response, Casey Family Programs, in collaboration with the National Council of Juvenile and Family Court Judges' Permanency Planning for Children Department, developed a Judicial Checklist with key educational questions to be asked from the bench. The Checklist has become a useful tool for juvenile and family court judges when assessing the effectiveness of current educational placements of the children who come before their courts, tracking their performance, and in making a positive future impact on their educational outcomes.
Children and Young People in Conflict with the Law: Asking the Hard Questions
Authors: BECROFT ANDREW J.
Published: July 2009

Shocking crimes elicit calls to “get tough” on youth offenders, but knee‐jerk responses are inappropriate and potentially dangerous. Although accountability and deterrence are important, rehabilitation is vital for young people who are more likely to benefit from such measures than their adult counterparts. However, balancing these factors raises a number of hard questions. For example, at what age should children be held criminally responsible for their actions, what is the correct role of welfare assistance in the process, and to what extent should state power to deal with child offending be transferred to families, victims, and communities? In assessing eight of these “hard questions,” this paper calls for a principled approach to the treatment of child and youth offenders in line with international human rights instruments.
The RWJF Reclaiming Futures Initiative: Improving Substance Abuse Interventions for Justice‐Involved Youths
Authors: NISSEN LAURA BURNEY , BUTTS JEFFREY A. , MERRIGAN DANIEL , KRAFT M. KATHERINE
Published: July 2009

Juvenile justice systems in the United States do not always respond effectively to substance abuse problems among young offenders. In 2002, the Robert Wood Johnson Foundation launched a 10‐community demonstration project to address this problem. Reclaiming Futures (RF) relies on community partnerships to improve treatment quality, strengthen local leadership, expand inter‐organizational collaboration, and create systems of shared performance management. The initial findings of a cross‐site evaluation suggest that Reclaiming Futures is yielding important and positive change. Bi‐annual surveys of key informants measure the quality and integration of juvenile justice and substance abuse treatment systems in each community. Of 13 indices measured by the surveys, 11 showed significant improvements between 2003 and 2005.
Family Values: How Children's Lawyers Can Help Their Clients by Advocating for Parents
Authors: GOTTLIEB CHRIS , PITCHAL ERIK S.
Published: July 2009

Children's lawyers too often view themselves as standing in opposition to parents in dependency proceedings. In this article, the authors argue that child advocates do a disservice to their clients by not using their considerable skills, role advantages, and moral authority to actively help parents. Noting that areas of common ground far exceed those places where the children's bar and the parents' bar might part company, the authors contend that children's lawyers have an obligation to actively fight for parents' rights. In particular, spending time early in a case to ensure that appropriate reunification services are being offered is well worth the investment, as it redounds to the benefit of all parties. Several concrete practice tips are offered regarding how children's lawyers can better serve their clients by regularly advocating for parents.
Menacing or Mimicking? Realities of Youth Gangs
Authors: HOWELL JAMES C.
Published: July 2009

Since the 1980s, youth gangs in the United States have been a high priority for law enforcement and the subject of a great deal of media attention, particularly in urban areas. Despite all the attention given to them, youth gangs remain poorly defined and vaguely characterized, and in many less populated communities, myths about youth gangs complicate the determination of appropriate community responses. To assist communities in combating gangs, this article illuminates numerous gang myths and contrasts them with research‐based realities. It concludes with implications and recommendations for community—including juvenile court—responses to gangs.
Aftercare Reality and Reform
Authors: GRIFFIN PATRICK , STEELE RICHARD , FRANKLIN KELLY
Published: July 2009

Aftercare is widely acknowledged to be a weak link in the juvenile justice continuum. This report describes Pennsylvania's recent efforts to envision and articulate a comprehensive aftercare system, to assess current local variations in aftercare practice in light of that vision, and to bring about the state‐ and county‐level reforms that will make comprehensive aftercare a reality statewide.
Cross‐feeding of methane carbon among bacteria on rice roots revealed by DNA‐stable isotope probing
Authors: Qiu Qiongfen , Conrad Ralf , Lu Yahai
Published: July 2009

Most of methane in flooded rice fields is emitted via transport through the plant gas vascular system. In the reverse direction, oxygen is diffusing to the living roots, and hence, the rhizosphere and roots of rice serve as an important habitat for CH4 oxidation which reduces CH4 emission from flooded rice fields. A laboratory incubation experiment was performed to determine the activity and composition of the methanotrophic Proteobacteria inhabiting the rice root system. Excised root material from young‐ and old‐nodal roots was collected and used for aerobic incubation in the presence of 13C‐labelled CH4. Prior to the incubation, the root material was treated with ammonium to test the effect of N availability on the activity of methanotrophs. Analyses of pmoA genes revealed that type II methanotrophs related to Methylocystaceae were predominant and remained relatively stable during the incubation regardless of root material and ammonium treatments. The abundance of type I methanotrophs was much smaller but their composition was relatively more variable. 16S rDNA‐based stable isotope probing revealed that Sphingomonadales and methanotrophic Methylocystaceae were the most active bacteria assimilating CH4‐derived carbon on young‐nodal roots, whereas methylotrophic Methylophilales were active on old‐nodal roots. These observations indicate the existence on rice roots of a bacterial food web that is driven by CH4‐derived carbon.
The quest for atmospheric methane oxidizers in forest soils
Authors: Kolb Steffen
Published: July 2009

Aerobic methanotrophs in forest soils are the largest biological sink for atmospheric methane (CH4). Community structures in 53 soils from Europe, Russia, North and South America, Asia and New Zealand located in boreal, temperate and tropical forests were analysed and maximal abundances of 2.1 × 107 methanotrophs g−1 DW were measured. In acidic soils, the most frequently detected pmoA genotypes were Upland Soil Cluster α (USCα) and Methylocystis spp. Phospholipid fatty acids that were labelled by consumption of 14/13CH4 suggested the activity of type II methanotrophs. Cluster 1 (Methylocystaceae), USCγ and Methylocystis spp. were frequently detected genotypes in pH‐neutral soils. Genotypes with ambiguous functional affiliation were co‐detected (Clusters MR1, RA21, 2) and may represent aerobic methanotrophs, ammonia oxidizers or enzymes with an unknown function. The physiological traits of atmospheric CH4 oxidizers are largely unknown because organisms possessing the key forest soil pmoA genotypes (USCα, USCγ, Cluster 1) have not been cultivated. Some methanotrophic strains belonging to the family Methylocystaceae have been shown to oxidize CH4 at atmospheric mixing ratios. Methylocystis strain SC2 was found to have an alternative particulate CH4 monooxygenase responsible for CH4 oxidation at atmospheric mixing ratios. pH, forest type and temperature might be environmental factors that shape methanotrophic communities in forest soils. However, specific effects on individual species are largely unknown, and only a limited number of studies have addressed environmental controls of methanotrophic diversity, pointing to the need for future research in this area.
Sequential Low‐Dose Rate Half‐Body Irradiation and Chemotherapy for the Treatment of Canine Multicentric Lymphoma
Authors: Lurie D.M. , Gordon I.K. , Théon A.P. , Rodriguez C.O. , Suter S.E. , Kent M.S.
Published: July 2009

Background: Sequential half‐body irradiation (HBI) combined with chemotherapy is feasible in treating canine lymphoma, but prolonged interradiation intervals may affect efficacy. A 2‐week interradiation interval is possible in most dogs receiving low‐dose rate irradiation (LDRI) protocols at 6 Gy dose levels.

Hypothesis: LDRI incorporated into a cyclophosphamide, doxorubicin, vincritine, and prednisone (CHOP)‐based chemotherapy protocol is effective for the treatment of lymphoma in dogs.

Animals: Thirty‐eight client‐owned animals diagnosed with multicentric lymphoma.

Methods: Retrospective study evaluating the efficacy and prognostic factors for the treatment of canine lymphoma with sequential HBI and chemotherapy.

Results: The median 1st remission was 410 days (95% confidence interval [CI] 241–803 days). The 1‐, 2‐, and 3‐year 1st remission rates were 54, 42, and 31%. The median overall survival was 684 days (95% CI 334–1,223 days). The 1‐, 2‐, and 3‐year survival rates were 66, 47, and 44%.

Conclusions and Clinical Relevance: Results of this study suggest that treatment intensification by a 2‐week interradiation treatment interval coupled with interradiation chemotherapy is an effective treatment for dogs with lymphoma.
DIFFUSION INDUCED SHIFT OF BIFURCATION POINT IN A MANGROVE ECOSYSTEM FOOD‐CHAIN MODEL WITH HARVESTING
Authors: MUKHOPADHYAY B. , BHATTACHARYYA R.
Published: July 2009

Abstract The present paper deals with a detritus‐based food‐chain model within a mangrove ecosystem. The top predator (mainly fish) is assumed to have a commercial value and undergoes harvesting. Stability and bifurcation behavior of the model is studied and a threshold harvest rate is obtained. Next we introduce environmental nonhomogenity into the model equation. The resulting reaction diffusion system is investigated, and the criteria for supercritical Hopf bifurcation is obtained using the method of Lyapunov first coefficient. A comparison of the critical harvest rates under the homogeneous and the nonhomogeneous context is performed both analytically and numerically.
Biaxial strain and variable stiffness in aponeuroses
Authors: Azizi Emanuel , Roberts Thomas J.
Published: July 2009

The elastic structures of many muscles include both an extramuscular free tendon as well as a sheet‐like aponeurosis. An important distinguishing feature of aponeuroses is that these tendinous structures function as the attachment and insertion surfaces of muscle fascicles and therefore surround a substantial portion of the muscle belly. As a result, aponeuroses must expand both parallel (longitudinal) and perpendicular (transverse) to a muscle's line of action when contracting muscles bulge to maintain a constant volume. In this study, we use biplanar high‐speed fluoroscopy to track the strain patterns of the turkey lateral gastrocnemius aponeurosis during active and passive force production in situ. We find that the behaviour of the aponeurosis during passive force production is consistent with uniaxial loading, as aponeuroses stretch only in the longitudinal direction. By contrast, our results show that aponeuroses are stretched in both longitudinal and transverse directions during active force production and that transverse strains are on average 4 times greater than longitudinal strains. Biaxial loading of aponeuroses appears to effectively modulate longitudinal stiffness, as we find the measured stiffness in the longitudinal direction varies in proportion to transverse strain. We conclude that biaxial strain during active force production distinguishes aponeuroses from free tendons and may function to dynamically modulate stiffness along the axis of muscle force production. It is likely that consideration of strains measured only in the longitudinal direction result in an underestimation of aponeurosis stiffness as well as its capacity for elastic energy storage.
Energy turnover in relation to slowing of contractile properties during fatiguing contractions of the human anterior tibialis muscle
Authors: Jones David A. , Turner Duncan L. , McIntyre David B. , Newham Di J.
Published: July 2009

Slowing and loss of muscle power are major factors limiting physical performance but little is known about the molecular mechanisms involved. The slowing might be a consequence of slow detachment of cross bridges and, if this were the case, then a reduction in the ATP cost of an isometric contraction would be expected as the muscle fatigued. The human anterior tibialis muscle was stimulated repeatedly under ischaemic conditions at 50 Hz for 1.6 s with a 50% duty cycle and muscle metabolites measured by 31P magnetic resonance spectroscopy. Over the course of 20 contractions the half‐time of relaxation increased from 36.5 ± 0.09 ms (mean ±s.e.m.) to 113 ± 17 ms and isometric force was reduced to 63 ± 3% of the initial value. ATP turnover was determined from the change in high energy phosphates and lactate production, the latter estimated from the change of intracellular pH. ATP turnover over the first three contractions was 2.45 ± 0.09 mm s−1 and decreased to 1.8 ± 0.06 mm s−1 over the last five tetani. However, when this latter value was normalised for the decrease in isometric force, it became 2.56 ± 0.3 mm s−1, which is the same as the turnover of the fresh muscle. The data suggest that the rate of cross bridge detachment is unaffected by fatigue and are consistent the suggestion that it is the rate of attachment which is slowed rather than the rate of detachment. The present results focus attention on stages in the cross bridge cycle concerned with attachment and the transition from low to high force states that may be influenced by metabolic changes in the fatiguing muscle.
Effects of probiotics and commensals on intestinal epithelial physiology: implications for nutrient handling
Authors: Resta Silvia C.
Published: July 2009

Eukaryotes and prokaryotes have developed mutually beneficial relationships over millennia of evolutionary adaptation. Bacteria in our gut rely on our diet and the protected environment of our bodies just as our health depends on byproducts of microbial metabolism. Microorganisms of the gut microbiota ferment carbohydrates into short‐chain fatty acids, convert dietary and endogenous nitrogenous compounds into ammonia and microbial protein, and synthesize and activate B vitamins and vitamin K. The benefit from their activity is multiplex and translates into increased energy for the gut epithelial cells, balanced absorption of salt and water, nitrogen recycling, breakdown of complex lipids and cholesterol, and detoxification of waste compounds.
Estimating Damping Parameters in Multi-Degree-of-Freedom Vibration Systems by Balancing Energy
Authors: Feeny B. F.
Published: July 2009

A method of estimating damping parameters for multi-degree-of-freedom vibration systems is outlined, involving a balance of dissipated and supplied energies over a cycle of periodic vibration. The power is formulated as the inner product between the velocity and force terms and integrated over a cycle. Conservative terms (mass and stiffness) drop out of the formulation. The displacement response and the input are measured, and the damping coefficients are estimated without knowledge of the mass and stiffness, which can be nonlinear, as illustrated in one example. The identification equations are also obtained with a modal reduction based on proper orthogonal decomposition. The method can be applied with a harmonic motion assumption or by simple numerical integration. The method is illustrated with linear and quadratic damping, in simulations of a four degree-of-freedom system, and in a string with and without noise.
Interaction of Hydrogen Transport and Material Elastoplasticity in Pipeline Steels
Authors: Dadfarnia Mohsen , Somerday Brian P. , Sofronis Petros , Robertson Ian M. , Stalheim Douglas
Published: July 2009

The technology of large scale hydrogen transmission from central production facilities to refueling stations and stationary power sites is at present undeveloped. Among the problems that confront the implementation of this technology is the deleterious effect of hydrogen on structural material properties, in particular, at gas pressures of the order of 15MPa, which are the suggested magnitudes by economic studies for efficient transport. In order to understand the hydrogen embrittlement conditions of the pipeline materials, we simulate hydrogen diffusion through the surfaces of an axial crack on the internal wall of a vessel coupled with material deformation under plane strain small scale yielding conditions. The calculation of the hydrogen accumulation ahead of the crack tip accounts for stress-driven transient diffusion of hydrogen and trapping at microstructural defects whose density evolves dynamically with deformation. The results are analyzed to correlate for a given material system the time after which hydrogen transport takes place under steady state conditions with the level of load in terms of the applied stress intensity factor at the crack tip and the size of the domain used for the simulation of the diffusion.
Frequency Band Averaging of Spectral Densities for Updating Finite Element Models
Authors: Kammer Daniel C. , Nimityongskul Sonny
Published: July 2009

The successful operation of proposed precision spacecraft will require finite element models that are accurate to much higher frequencies than the standard application. The hallmark of this mid-frequency range, between low-frequency modal analysis and high-frequency statistical energy analysis, is high modal density. The modal density is so high, and the sensitivity of the modes with respect to modeling errors and uncertainty is so great that test/analysis correlation and model updating based on traditional modal techniques no longer work. This paper presents an output error approach for finite element model updating that uses a new test/analysis correlation metric that maintains a direct connection to physical response. The optimization is gradient based. The metric is based on frequency band averaging of the output power spectral densities with the central frequency of the band running over the complete frequency range of interest. The results of this computation can be interpreted in several different ways, but the immediate physical connection is that it produces the mean-square response, or energy, of the system to random input limited to the averaging frequency band. The use of spectral densities has several advantages over using frequency response directly, such as the ability to easily include data from all inputs at once, and the fact that the metric is real. It is shown that the averaging process reduces the sensitivity of the optimization due to resonances that plague many output error model updating approaches.
SEA Coupling Loss Factors of Complex Vibro-Acoustic Systems
Authors: Totaro N. , Dodard C. , Guyader J. L.
Published: July 2009

Reliability of statistical energy analysis (SEA) models depends on good estimates of coupling loss factors (CLFs), modal densities, and damping loss factors. Statistical modal energy distribution analysis (SmEdA), a finite element based method to compute CLFs from uncoupled finite elements models of subsystems, is used to generate SEA CLF for general subsystems. This method is based on the basic SEA relations for coupled oscillators and on a dual modal formulation to describe the vibration of coupled subsystems. Previous works have demonstrated the use of the SmEdA method for structure-to-structure couplings. The current work extends the SmEdA process to structure-to-cavity couplings. The estimation of CLF using the SmEdA approach is compared, for a simple test case, to analytical results and a classical expression obtained with a wave approach. Results show good comparison with analytical results even below critical frequency, where the wave approach underestimates CLF. Finally, an industrial application has been carried out to demonstrate that the SmEdA approach can be used in the case of complex structures.
Reliability Based Design and Assessment for Location-Specific Failure Threats With Application to Natural Gas Pipelines
Authors: Nessim Maher , Zhou Wenxing , Zhou Joe , Rothwell Brian
Published: July 2009

The acceptance criteria used in reliability based design and assessment are defined as a set of reliability targets (where reliability is defined as 1.0 minus the probability of failure). Because of the linear nature of pipeline systems, reliability targets are defined on a per kilometer-year basis. Such targets are directly applicable to failure causes (or limit states) that are equally likely to occur anywhere along a segment of the pipeline (e.g., equipment impact or yielding/rupture of defect-free pipe under internal pressure). They are, however, not directly applicable for design and assessment situations involving limit states that apply at known specific locations. Examples include design for geotechnical loads on a particular unstable slope or integrity assessment of a corrosion defect at a specific location (as determined by in-line inspection). In previous work, reliability targets for natural gas pipelines have been developed on the basis of appropriate societal and individual risk criteria. This paper describes an approach to adapt these targets and demonstrate compliance with them, for location-specific limit states. The approach is based on using separate checks to ensure that the individual and societal risk criteria underlying the targets are met. An example is included to demonstrate application of the approach to design a pipeline on an unstable slope.
Accurate Simulation Solutions of Euler Angular Velocity/Acceleration and Statics of Parallel Manipulators by CAD Variation Geometry
Authors: Lu Yi , Xu Jiayin , Yu JianPing , Hu Bo
Published: July 2009

A CAD variation geometry approach is proposed for accurately solving the Euler angles, Euler angular velocity/acceleration, and the active forces due to a concentrated torque of limited-DOF parallel manipulators (PMs). First, a simulation mechanism of PM with Euler angles, a simulation mechanism of PM with Euler angular velocity/acceleration, and a simulation mechanism of PM with Euler angular torques are created and combined into one simulation mechanism. Second, when modifying the driving dimension of the active legs, the simulation mechanism of PM is varied correspondingly, and the Euler angles, Euler angular velocity/acceleration, and active forces due to the concentrated torque are solved automatically and visualized dynamically. Third, a 3DOF PM and a 5DOF PM are illustrated, and their Euler angles, Euler angular velocity/acceleration, and active forces due to the concentrated torque are solved accurately by CAD variation geometry and are verified by the analytic solutions.
A Review on Current Status of Alloys 617 and 230 for Gen IV Nuclear Reactor Internals and Heat Exchangers 1
Authors: Ren Weiju , Swindeman Robert
Published: July 2009

Alloys 617 and 230 are currently identified as two leading candidate metallic materials in the down selection for applications at temperatures above 760°C in the Gen IV nuclear reactor systems. Qualifying the materials requires significant information related to codification, mechanical behavior modeling, metallurgical stability, environmental resistance, and many other aspects. In the present paper, material requirements for the Gen IV nuclear reactor systems are discussed; available information regarding the two alloys for the intended applications are reviewed and analyzed; and further R&D activities are suggested. In the United States the major requirement for qualifying the materials is to satisfy the ASME Subsection NH, with adequate considerations for NRC, ASME NQA-1, and Section XI. In comparison, Alloy 617 is more studied with larger existing databases in air and helium, while Alloy 230 may have highly desired potentials but needs more exploration. To provide a sound technical basis for the material selection decision, more data should be generated to characterize behaviors of both alloys in creep, loading rate sensitivity, fatigue, creep-fatigue, crack resistance, toughness, product form dependency, and metallurgical stability.
Exact, Hierarchical Solutions for Localized Loadings in Isotropic, Laminated, and Sandwich Shells
Authors: Carrera E. , Giunta G.
Published: July 2009

This paper presents closed form solutions for simply supported cylindrical and spherical shells subjected to uniform localized distributions of transverse pressure and bending moment. These distributions have been expanded in terms of Fourier’s series for which Navier type “exact” solutions have been found for the governing differential equations of the employed shell theories. Shells made of isotropic materials, composites laminates, and sandwich have been analyzed. Carrera’s unified formulation has been adopted in order to implement a large variety of two-dimensional theories. Classical, refined, zigzag, layerwise, and mixed theories are compared in order to evaluate the stress and deformation variables. Conclusions are drawn with respect to the accuracy of the various theories for the considered loadings and layouts. The importance of the refined shell models in order to describe accurately the three-dimensional stress state in the neighborhood of the localized loading application area is outlined.
Delayed Hydride Cracking Initiation at Notches in Zr-2.5Nb Alloys
Authors: Cui Jun , Shek Gordon K. , Scarth D. A. , Wang Zhirui
Published: July 2009

Delayed hydride cracking (DHC) is an important crack initiation and growth mechanism in Zr-2.5Nb alloy pressure tubes of CANDU nuclear reactors. DHC is a repetitive process that involves hydrogen diffusion, hydride precipitation, growth, and fracture of a hydrided region at a flaw tip. In-service flaw evaluation requires analyses to demonstrate that DHC will not initiate from the flaw. The work presented in this paper examines DHC initiation behavior from V-notches with root radii of 15 μm, 30 μm, and 100 μm, which simulate service-induced debris fretting flaws. Groups of notched cantilever beam specimens were prepared from two unirradiated pressure tubes hydrided to a nominal hydrogen concentration of 57 wt. ppm. The specimens were loaded to different stress levels that straddled the threshold value predicted by an engineering process-zone (EPZ) model, and subjected to multiple thermal cycles representative of reactor operating conditions to form hydrides at the notch tip. Threshold conditions for DHC initiation were established for the notch geometries and thermal cycling conditions used in this program. Test results indicate that the resistance to DHC initiation is dependent on notch root radius, which is shown by optical metallography and scanning electron microscopy to have a significant effect on the distribution and morphology of the notch-tip reoriented hydrides. In addition, it is observed that one tube is less resistant to DHC initiation than the other tube, which may be attributed to the differences in their microstructure and texture. There is a reasonable agreement between the test results and the predictions from the EPZ model.
Literature Survey of Gaseous Hydrogen Effects on the Mechanical Properties of Carbon and Low Alloy Steels
Authors: Lam P. S. , Sindelar R. L. , Duncan A. J. , Adams T. M.
Published: July 2009

A compendium of mechanical properties of carbon and low alloy steels following hydrogen exposure has been assembled from literature sources. The property sets include yield strength, ultimate tensile strength, uniform elongation, reduction in area, threshold stress intensity factor, fracture toughness, and fatigue crack growth. These properties are from literature sources under a variety of test methods and conditions. The collection of literature data is by no means complete, but the diversity of data and dependency of results on test method are sufficient to warrant a design and implementation of a standardized test program. The program would be needed to enable a defensible demonstration of structural integrity of a pressurized hydrogen system. It is essential that the environmental variables be well-defined (e.g., the applicable hydrogen gas pressure range and the test strain rate) and the specimen preparation be realistically consistent (such as the techniques to charge hydrogen and to maintain the hydrogen concentration in the specimens).
Periodic Motions With Impacting Chatter and Stick in a Gear Transmission System
Authors: Luo Albert C. J. , O’Connor Dennis
Published: July 2009

In this paper, an impact model with possible stick between the two gears is proposed for gear transmission systems, which includes the piecewise backlash model and the traditional impact model for the first time. The new model presented in this paper possesses a time-varying boundary for two dynamical systems either to switch or to impact. Such a model can catch impacting chatter and stick phenomena in gear transmission systems. Based on the new model, periodic impacting chatter and stick in a gear transmission system can be investigated. For doing so, switching sets on the time-varying boundaries are introduced to define basic mappings. Mapping structures based on basic mappings are developed for characterizing motions in gear transmission systems, and from such mapping structures, periodic motions with impacting chatter and stick in such a gear transmission system are predicted analytically. Numerical simulations are performed for illustration of periodic motions with impacting chatter and stick phenomena.
Automated Operating Mode Classification for Online Monitoring Systems
Authors: Timusk Markus A. , Lipsett Michael G. , McBain Jordan , Mechefske Chris K.
Published: July 2009

Transient operation of machinery can greatly complicate the task of vibration-based online condition monitoring. Because the operating mode of a machine affects the physical response and hence the diagnostic parameters, real-time information regarding the operating mode is likely to improve the performance of an online fault detection system. This paper proposes a method for automated operating mode classification to augment the performance of vibration-based online condition monitoring systems for applications such as gearboxes, motors, and their constituent components. Experimental work has been carried out on the swing machinery of an electromechanical excavator, which demonstrates how such a method might function on actual dynamic signals gathered from an operating machine. Several variations of the system have been tested and found to be successful.
Vibration Suppression of Rotating Machinery Utilizing an Automatic Ball Balancer and Discontinuous Spring Characteristics
Authors: Liu Jun , Ishida Yukio
Published: July 2009

Automatic ball balancer is a balancing device where two balls inside a hollow rotor move to optimal rest positions automatically to eliminate unbalance. As a result, vibrations are suppressed to the zero amplitude in the rotational speed range higher than the major critical speed. However, it has the following defects. The amplitude of vibration increases in the rotational speed range lower than the major critical speed. In addition, almost periodic motions with large amplitude occur in the vicinity of the major critical speed due to the rolling of balls inside the rotor. Because of these defects, an automatic ball balancer has not been used widely. This paper proposes the vibration suppression method utilizing the discontinuous spring characteristics together with an automatic ball balancer to overcome these defects and to suppress vibration. The validity of the proposed method is confirmed theoretically, numerically, and experimentally. The results show that amplitude of vibration can be suppressed to a small amplitude in the vicinity of the major critical speed and the zero amplitude in the range higher than the major critical speed.
Experimental Evaluation of a Unified Time-Scale-Frequency Technique for Bearing Defect Feature Extraction
Authors: Yan Ruqiang , Gao Robert X. , Wang Changting
Published: July 2009

A systematic experimental study is presented in this paper on evaluating the effectiveness of a unified, multidomain algorithm for defect feature extraction in bearing condition monitoring and health diagnosis. The algorithm decomposes vibration signals measured on bearings by discrete wavelet transform and subsequently performs the Fourier transform on the wavelet coefficients. The effectiveness of such a unified technique is demonstrated through experimental case studies, which confirmed its advantage over the wavelet or Fourier transform techniques employed alone. Also, the unified technique has shown to be computationally more efficient than the enveloping technique based on continuous wavelet transform, thus providing a good signal processing tool for bearing defect diagnosis.
A New Method to Calculate the Force and Moment Workspaces of Actuation Redundant Spatial Parallel Manipulators
Authors: Garg Venus , Carretero Juan A. , Nokleby Scott B.
Published: July 2009

A new method for obtaining the force and moment workspaces of spatial parallel manipulators (PMs) is presented. Force and moment workspaces are regions within which a manipulator can sustain/apply at least a certain value of force or moment in all directions. Here, the force and moment workspaces are found using a method, which explicitly sets the largest possible number of actuators to their maximum limits ensuring that the manipulator is performing at its best possible wrench capabilities. Two cases for obtaining these workspaces are used. The first gives the applicable/sustainable force with a prescribed moment whereas the second one gives the applicable/sustainable moment with a prescribed force. For illustration purposes, the method is applied to a six-degree-of-freedom (DOF) redundantly-actuated spatial PM, the 3-RRṞS. The results are represented graphically as the boundaries of the workspace in the three-dimensional Cartesian space. These workspaces can be used as a powerful tool for path/task planning and PM design.
Maximal Singularity-Free Total Orientation Workspace of the Gough–Stewart Platform
Authors: Jiang Qimi , Gosselin Clément M.
Published: July 2009

The maximal singularity-free total orientation workspace is highly desirable in a context of design of parallel robots. In practice, this type of workspace is interesting because a parallel robot often works in a given range of orientations. In this work, an algorithm is presented to compute the maximal singularity-free total orientation workspace of the Gough–Stewart platform. In order to demonstrate the presented algorithm, an example is provided.
Overload Fracture of Hydrided Region at Simulated Blunt Flaws in Zr-2.5Nb Pressure Tube Material
Authors: Cui Jun , Shek Gordon K. , Wang Zhirui
Published: July 2009

A crack initiation and growth mechanism known as delayed hydride cracking (DHC) is a concern for Zr-2.5Nb alloy pressure tubes of CANada Deuterium Uranium or CANDU (CANDU is a trademark of the Atomic Energy of Canada Limited, Ontario, Canada) nuclear reactors. DHC is a repetitive process that involves hydrogen diffusion, hydride precipitation, formation, and fracture of a hydrided region at a flaw tip. An overload occurs when the flaw-tip hydrided region is loaded to a stress, higher than that at which this region is formed. For the fitness-for-service assessment of the pressure tubes, it is required to demonstrate that the overload from the normal reactor operating and transient loading conditions will not fracture the hydrided region, and will not initiate DHC. In this work, several series of systematically designed, monotonically increasing load experiments are performed on specimens, prepared from an unirradiated pressure tube with hydrided region, formed at flaws with a root radius of 0.1 mm or 0.3 mm, under different hydride formation stresses and thermal histories. Crack initiation in the overload tests is detected by the acoustic emission technique. Test results indicate that the resistance to overload fracture is dependent on a variety of parameters including hydride formation stress, thermal history, hydrogen concentration, and flaw geometry.
Burst Pressure of Pressurized Cylinders With Hillside Nozzle
Authors: Wang H. F. , Sang Z. F. , Xue L. P. , Widera G. E. O.
Published: July 2009

The burst pressure of cylinders with hillside nozzle is determined using both experimental and finite element analysis (FEA) approaches. Three full-scale test models with different angles of the hillside nozzle were designed and fabricated specifically for a hydrostatic test in which the cylinders were pressurized with water. 3D static nonlinear finite element simulations of the experimental models were performed to obtain the burst pressures. The burst pressure is defined as the internal pressure for which the structure approaches dimensional instability, i.e., unbounded strain for a small increment in pressure. Good agreement between the predicted and measured burst pressures shows that elastic-plastic finite element analysis is a viable option to estimate the burst pressure of the cylinders with hillside nozzles. The preliminary results also suggest that the failure location is near the longitudinal plane of the cylinder-nozzle intersection and that the burst pressure increases slightly with an increment in the angle of the hillside nozzle.
Flow-Acoustic Coupling in T-Junctions: Effect of T-Junction Geometry
Authors: Ziada S. , McLaren K. W. , Li Y.
Published: July 2009

The flow-acoustic coupling mechanism in a T-junction, which combines flows from two branches, forming the “cross-bar” of the T-junction, into one pipe, forming the “stem” of the T-junction, is investigated experimentally. The T-junction has a step pipe expansion at its inlets. The shear layer separating from this step expansion is found to excite intense acoustic resonances over multiple ranges of flow velocity. The excited acoustic mode is confined to the branch pipes and has an acoustic pressure node at the centerline of the T-junction. The length of the expansion section of the T-junction is found to control the frequency of the shear layer oscillation and therefore determines the ranges of flow velocity over which acoustic resonances are excited. Introducing asymmetry in the T-junction expansion length has shown little influence on the excitation of acoustic resonance. An additional T-junction arrangement made of rectangular cross-sectional ducts is also investigated to facilitate a flow visualization study of unsteady flow structures in the T-junction during acoustic resonance, and thereby improve understanding of the acoustic resonance mechanism and the nature of the aero-acoustic sources in the T-junction.
In Vitro Trafficking and Efficacy of Core-Shell Nanostructures for Treating Intracellular
Salmonella
Infections
Authors: Ranjan A. , Pothayee N. , Seleem M. N. , Sriranganathan N. , Kasimanickam R. , Makris M. , Riffle J. S.
Published: July 2009

Nanostructures encapsulating gentamicin and having either amphiphilic (N1) or hydrophilic (N2) surfaces were designed. Flow cytometry and confocal microscopy studies demonstrated a higher rate of uptake for amphiphilic surfaces. A majority of N1 were localized in the cytoplasm, whereas N2 colocalized with the endosomes/lysosomes. Colocalization was not observed between nanostructures and intracellular
Salmonella
bacteria. However, significant in vitro reductions in bacterial counts (0.44 log
10
) were observed after incubation with N1, suggesting that the surface property of the nanostructure influences intracellular bacterial clearance.