bluuebunny/crossref_metadata_2025 huggingface dataset:
MYC translocation and an increased copy number predict poor prognosis in adult diffuse large B‐cell lymphoma (DLBCL), especially in germinal centre‐like B cell (GCB) type
Authors: Yoon S O , Jeon Y K , Paik J H , Kim W Y , Kim Y A , Kim J E , Kim C W
Published: July 2008

Aims:  Diffuse large B‐cell lymphoma (DLBCL) is a heterogeneous disease with various genetic alterations. The aim was to investigate MYC, Bcl‐2 and Bcl‐6 translocations and copy number changes in adult DLBCLs to evaluate their clinicopathological features and prognostic implications.

Methods and results:  Gene status was examined using fluorescence in situ hybridization (FISH), and the results were analysed in the context of germinal centre B‐cell (GCB) and non‐GCB type of DLBCL based on immunohistochemistry. MYC translocation was observed in 9% (14 of 156), and an increased copy number (ICN) in 7.1% (11 of 156). MYC translocation was more common in GCB type (22%) than in non‐GCB type (4.9%), and associated with advanced International Prognostic Index (IPI). MYC aberration, i.e. translocation or increased copy number (ICN), was significantly associated with shorter overall survival, especially for the GCB type. Bcl‐2 translocation was rare (3.4%, five of 145), and ICN was observed in 11.7% (17 of 145), more frequently in non‐GCB type (16%) than in GCB type (2.5%). Bcl‐2 aberration tended to have an adverse effect on survival. In multivariate analysis, MYC ICN was an independent poor prognostic factor.

Conclusions:  Analyses of MYC and Bcl‐2 status, i.e. translocation and ICN, in the context of DLBCL phenotype might help predict prognosis and determine therapeutic strategies.
Prognostic value of various morphometric measurements of tumour extent in prostate needle core tissue
Authors: Brimo F , Vollmer R T , Corcos J , Kotar K , Bégin L R , Humphrey P A , Bismar T A
Published: July 2008

Aims:  Predicting prostatic cancer patients’ outcome is a major objective for clinicians and patients. Several nomograms are currently implemented prior to treatment to help predict clinical and pathological outcome. The aim of this study was to investigate the prognostic significance of morphometric measurements of cancer on the needle biopsy specimen in relation to the final pathological stage or the biochemical failure status following radical prostatectomy, and to determine which measurement of tumour length in cases with discontinuous foci of cancer (DFC) is most reliably reflective of the pathological stage.

Methods and results:  Of the 100 patients included in this study, 34% had high‐stage disease (pT ≥ 3 and/or pN1) and 16% experienced biochemical recurrence. The analysis showed that fraction of positive cores, total percentage of cancer and both total and greatest millimetric cancer lengths were the variables most closely associated with pathological stage and biochemical failure status.

Conclusions:  This study confirms the prognostic value of recording tumour extent in prostatic needle biopsy reporting. However, the results are inconclusive in determining the best method to record tumour length in cores with DFC and larger studies are needed to answer this question fully.
Yawning and subjective sleepiness in the elderly
Authors: ZILLI IOLE , GIGANTI FIORENZA , UGA VALERIA
Published: July 2008

Yawning is related to sleep/wake transitions and time of day, probably reflecting the time course of sleepiness. As aging modifies sleep–wake and sleepiness rhythms, we suppose that yawning frequency and its time course vary as a function of age. Thirteen aged healthy subjects (77.15 ± 4.09 years) and 12 young adults (24.41 ± 3.31 years) were instructed to keep their habitual sleep schedules for three consecutive work‐days, during which they were required to signal every yawning occurrence and to evaluate hourly their sleepiness level. Results showed that aged subjects yawn less frequently than young adults, particularly during morning and mid‐afternoon hours. The time course of yawning was different between the two age groups: aged subjects showed earlier morning peak and evening rise compared with young adults; in addition, aged subjects showed two minor peaks in‐between. Differences as a function of age in the time course of yawning were associated with differences in the time course of sleepiness. The only exception pertained to the early morning yawning peak, which was close to the awakening but it was not associated with high sleepiness in aged subjects. Our study discloses that aging modifies yawning frequency and its time course. Furthermore, as in the elderly yawning after the awakening is not associated with high sleepiness level as in young adult, we put forward that sleepiness level and the proximity of sleep/wake transitions could separately affect yawning.
Driving in Europe: the need of a common policy for drivers with obstructive sleep apnoea syndrome
Authors: RODENSTEIN DANIEL ,   ON BEHALF OF COST‐B26 ACTION ON SLEEP APNOEA SYNDROME
Published: July 2008

Obstructive sleep apnoea syndrome (OSA) increases the risk of motor vehicle crashes, and of all medical disorders, has greatest risk in this respect. There is no consistency in the way OSA is considered by the national ‘Physical Fitness to Drive’ legislations within the 27 member countries of the European Union (EU), and most ignore OSA. This is further reflected by the absence of any reference to OSA in Annex III of the Directive 91/439/EEC, harmonizing Driving License regulations in the EU. A recent meeting brought together experts from several European and other countries, together with a representative of the European Commission. They discussed the best way to design and implement a uniform policy within Europe, for OSA and driving. It was agreed that: (i) other forms of pathological sleepiness be included, (ii) it covers both private and professional drivers, (iii) police accident report forms should explicitly consider sleepiness as a potential cause, (iv) sleep–wake education should be incorporated into the mandatory program of continuous education for professional drivers, ideally from 2010, (v) driver screening methods should contain questions on sleepiness at the wheel, habitual snoring and witnessed apneas during sleep, as well as the Epworth Sleepiness Score and Body Mass Index and (vi) following effective and efficient treatment, patients should be permitted to drive. In the light of medical, scientific and technical progress, EU procedures exist to enable the rapid modification of existing legislation. If such a procedure could be enacted for these aspects of driver sleepiness, then roads would be safer for 400 million people.
Induction and maintenance therapy in ANCA‐associated systemic vasculitis
Authors: Menahem Solomon , Hiremagalur Balaji , Mudge David , Toussaint Nigel , Walters Giles
Published: July 2008

Date written: November 2006

Final submission: August 2007
Haemoglobin
Authors: McMahon Lawrence
Published: July 2008

Date written: April 2007

Final submission: February 2008
Adjuvant methotrexate, vinblastine, adriamycin, and cisplatin chemotherapy has potential to prevent recurrence of bladder tumors after surgical removal of upper urinary tract transitional cell carcinoma
Authors: Soga Norihito , Arima Kiminobu , Sugimura Yoshiki
Published: July 2008

Objectives:  To evaluate the efficacy of adjuvant platinum based chemotherapy in upper urinary tract urothelial cancer following surgical resection in terms of survival benefit and inhibition of bladder cancer recurrence.

Methods:  Between April 1986 and August 2005, a total of 132 patients with a diagnosis of upper urinary tract urothelial cancer underwent radical nephroureterectomy with cuff of bladder at our department. A total of 46 patients (13 with pT2pN0M0 and 33 with pT3 pN0M0 transitional cell carcinoma without prior bladder cancer) were enrolled. Patients with locally advanced disease were divided into two groups: the adjuvant chemotherapy group (24 patients) who received adjuvant methotrexate, vinblastine, adriamycin, and cisplatin (M‐VAC) and the non‐adjuvant chemotherapy group who did not receive adjuvant M‐VAC (22 patients).

Results:  There were no statistically significant differences in patient characteristics or 10‐year survival between the two groups. The recurrence rate in the non‐adjuvant chemotherapy group was significantly higher than in the adjuvant chemotherapy group (log‐rank test, P < 0.0001). Only non‐adjuvant chemotherapy was a significant and independent risk factor (hazard ratio 6.97) for the development of intravesical recurrence (P < 0.01).

Conclusion:  Adjuvant M‐VAC is an important optional adjuvant therapy and can prevent recurrent bladder tumors following surgery for upper urinary tract transitional cell carcinoma. To determine whether adjuvant chemotherapy has further benefit, a randomized study would be needed.
Back to the roots of the M/D/s queue and the works of Erlang, Crommelin and Pollaczek
Authors: Janssen A. J. E. M. , Van Leeuwaarden J. S. H.
Published: July 2008

A.K. Erlang introduced the M/D/s queue in 1917, while F. Pollaczek and C.D. Crommelin formalized the theory using complex analysis and transforms. Let D(s,λ) denote the stationary probability of experiencing no waiting time in the M/D/s queue with arrival rate λ and service requirement 1. We use D(s,λ) as a vehicle to give an overview of some of the results we obtained over the last years, including explicit characterizations of the roots, the derivation of infinite series from expressions in terms of roots using Fourier sampling and heavy‐traffic limits obtained from square‐root staffing. We propose to call D(s,λ) the Erlang D formula, for which several new results are presented and compared with the results of Pollaczek.
Scaling limits of two‐dimensional percolation: an overview
Authors: Camia Federico
Published: July 2008

We present a review of the recent progress on percolation scaling limits in two dimensions. In particular, we consider the convergence of critical crossing probabilities to Cardy's formula and of the critical exploration path to chordal stochastic Loewner evolution (SLE6), the full scaling limit of critical cluster boundaries, and near‐critical scaling limits.
On residual empirical processes of GARCH‐SM models: application to conditional symmetry tests
Authors: Laïb Naâmane , Lemdani Mohamed , Ould‐Saïd Elias
Published: July 2008

Abstract. Considering the generalized autoregressive conditionally heteroskedastic with stochastic mean (GARCH‐SM) model, we establish in this article the consistency and the weak representation of a functional of its residual empirical process. Based on this result, a symmetry test for GARCH‐SM model is developed. Simulations are given to show the asymptotic behaviour and normality of the test statistic.
NEW EVIDENCE FOR IRON AGE SECONDARY BURIAL PRACTICE AND BONE MODIFICATION FROM GUSSAGE ALL SAINTS AND MAIDEN CASTLE (DORSET, ENGLAND)
Authors: REDFERN REBECCA
Published: July 2008

Summary. The Middle and Late Iron Age samples of disarticulated human remains from the settlement site of Gussage All Saints and the hillfort of Maiden Castle (Dorset, England) were investigated for evidence of funerary rites. The samples were examined using osteological, forensic and archaeological methodologies for evidence of excarnation and secondary burial. The study found evidence for dry‐fractures, animal gnawing and peri‐mortem trauma, indicating that many individuals had received blunt‐force cranial fractures and/or weapon injuries at the time of death. The taphonomic indicators showed that bodies were excarnated, received secondary burial treatment and then selected skull and long bones were incorporated into structured deposits. Osteological analysis also showed that the majority of individuals were adult males, which corresponded to patterns of trauma in the inhumated sample from Dorset. Two bones also provided unique evidence within Dorset for the cultural modification of human remains.
High‐resolution visualization of airspace structures in intact mice via synchrotron phase‐contrast X‐ray imaging (PCXI)
Authors: Parsons David W. , Morgan Kaye , Donnelley Martin , Fouras Andreas , Crosbie Jeffrey , Williams Ivan , Boucher Richard C. , Uesugi Kentaro , Yagi Naoto , Siu Karen K. W.
Published: July 2008

Anatomical visualization of airspace‐containing organs in intact small animals has been limited by the resolution and contrast available from current imaging methods such as X‐ray, micro‐computed tomography and magnetic resonance imaging. Determining structural relationships and detailed anatomy has therefore relied on suitable fixation, sectioning and histological processing. More complex and informative analyses such as orthogonal views of an organ and three‐dimensional structure visualizations have required different animals and image sets, laboriously processed to gather this complementary structural information. Precise three‐dimensional anatomical views have always been difficult to achieve in small animals. Here we report the ability of phase‐contrast synchrotron X‐ray imaging to provide detailed two‐ and three‐dimensional visualization of airspace organ structures in intact animals. Using sub‐micrometre square pixel charge‐coupled device array detectors, the structure and anatomy of hard and soft tissues, and of airspaces, is readily available using phase‐contrast synchrotron X‐ray imaging. Moreover, software‐controlled volume‐reconstructions of tomographic images not only provide unsurpassed image clarity and detail, but also selectable anatomical views that cannot be obtained with established histological techniques. The morphology and structure of nasal and lung airways and the middle ear are illustrated in intact mice, using two‐ and three‐dimensional representations. The utility of phase‐contrast synchrotron X‐ray imaging for non‐invasively localizing objects implanted within airspaces, and the detection of gas bubbles transiting live airways, are other novel features of this visualization methodology. The coupling of phase‐contrast synchrotron X‐ray imaging technology with software‐based reconstruction techniques holds promise for novel and high‐resolution non‐invasive examination of airspace anatomy in small animal models.
Enregistering, Authorizing and Denaturalizing Identity in Indonesia
Authors: Goebel Zane
Published: July 2008

This article focuses on one aspect of processes of enregisterment in Indonesia, namely the ways in which institutional representations of language use formulate semiotic registers linking language use to performable social categories of personhood and relationship. I examine three types of institutional and thus authorized speech events: schooling, census practices, and television. Of particular interest are three patterns of representation which I exemplify with excerpts from three television series. The first is the language‐ethnicity link long established in colonial practices and found in all three institutional representations of language use. The second pattern relates primarily to some of the new inflections created as part of the first pattern, namely the representation of Indonesian as an index of the ethnic other. The third pattern of representation resembles a type of competing ideology where language‐ethnicity links are denaturalized through practices of adequation.[adequation, denaturalization, enregisterment, identity, Indonesia, media]
Socializing Puros Pericos (Little Parrots): The Negotiation of Respect and Responsibility in Antonero Mayan Sibling and Peer Networks
Authors: Reynolds Jennifer F.
Published: July 2008

This article examines family and peer practices of socialization that illuminate a culture specific social ontology of intentions (Duranti 2006). An interpretive approach to the study of children's language socialization and peer talk is adopted to analyze how local beliefs concerning children's socialization and development are afforded within multiparty participation frameworks that involve teasing and shaming routines. These routines are powerful discursive strategies in the everyday negotiation and co‐construction of peer politics and kin group social relationships. Data include ethnographic observational and naturally occurring video‐recorded quotidian interactions collected March 1998–March 1999 in San Antonio Aguas Calientes, a highland Guatemala Kaqchikel Maya town. [responsibility, intentionality, language socialization, peer talk‐in‐interaction]
Justifying Race Talk: Indexicality and the Social Construction of Race and Linguistic Value
Authors: Anderson Kate T.
Published: July 2008

When individuals link linguistic behavior to speaker identity, they justify the differentiation of social types based on speech style, and also attach social value to ways of speaking. This study examines ten interviewees' racial characterizations of pre‐recorded voices and highlights how they justify their identification of speaker types and speech styles as socially recognizable. Findings illustrate how interviewees formulate links between linguistic habits and social types with a range of accompanying interdiscursive justifications across orders of indexicality. Implications for theory and practice include connections between normative evaluative race talk and its role in the dialectic reproduction of language ideologies. [race talk, language ideologies, interdiscursivity, orders of indexicality, discourse analysis]
Can a Plantation be Fair? Paradoxes and Possibilities in Fair Trade Darjeeling Tea Certification
Authors: Besky Sarah
Published: July 2008

This paper explores interactions between the Indian government's colonially inspired Plantations Labour Act and TransFair USA's fair trade standards. Although fair trade makes claims to universalistic notions of social justice and workers' empowerment, what “fairness” means and how it is experienced varies by locale. In this paper, I discuss how state laws and fair trade certification agencies complement and contradict each other on Darjeeling tea plantations. I argue that by reinforcing neoliberal logic, fair trade undermines the state, which has maintained the responsibility of regulating the treatment of workers on plantations. Certification often leads to the dissolution of unions, which are regarded as a barrier to trade.
Life Stories, Law's Stories: Subjectivity and Responsibility in the Politicization of the Discourse of “Identity”
Authors: Greenhouse Carol J.
Published: July 2008

In this essay, my focus is on the politicization of “identity” as an aspect of political competition within the U.S. government at critical moments in the modern making (and unmaking) of rights. I draw on a comparison of two textual examples: transcripts of the hearings that yielded the Civil Rights Act of 1990 and a reading of Toni Morrison's The Bluest Eye. Their antithetical visions of identity offer a “way in” to a particular moment in the recent U.S. past when race was resignified in public policy debates that clarified the emergent political dominance of the conservative movement—and then partially reclaimed with the assertion of identity as a theoretical object in anthropology and adjacent academic fields.
Sovereign Time, Storied Moments: The Temporalities of Law, Tradition, and Ethnography in Hopi Tribal Court
Authors: Richland Justin B.
Published: July 2008

This article analyzes the temporalities that emerge in interactions before the tribal court of the Hopi Indian Nation. Particular attention will be paid to the interdiscursive strategies employed by courtroom interlocutors negotiating between adherence to Anglo‐legal notions of fact and norm, and the narratives of Hopi tradition regularly raised by litigants in property dispute hearings. It will be argued that such negotiations are at once central to the “sovereign time” that contemporary Hopi law instantiates for the Hopi Nation, but also stand in a complex relationship to the temporalities generated by the “storied moments” of Hopi litigants' tradition discourses. The effect is that these traditions get legally framed as sometimes near to, sometimes far from, the lives and times of Hopi people today. In conclusion, it will be suggested that similar tensions of norm and fact resound in certain critical assessments of anthropology in the 1980s and 1990s, particularly those that focus on the implicit orientations to time and temporality that rest at the heart of ethnography's representational practices and the authority they generate. [time; tradition; law; interdiscursivity; Hopi]
Frobenius fields for Drinfeld modules of rank 2
Authors: Cojocaru Alina Carmen , David Chantal
Published: July 2008

Let ϕ be a Drinfeld module of rank 2 over the field of rational functions $F=\mathbb {F}_q(T)$, with $\mathrm {End}_{\bar {F}}(\phi ) = \mathbb {F}_q[T]$. Let K be a fixed imaginary quadratic field over F and d a positive integer. For each prime $\mathfrak {p}$ of good reduction for ϕ, let $\pi _{\mathfrak {p}}(\phi )$ be a root of the characteristic polynomial of the Frobenius endomorphism of ϕ over the finite field $\mathbb {F}_q[T] / \mathfrak {p}$. Let Πϕ(K;d) be the number of primes $\mathfrak {p}$ of degree d such that the field extension $F(\pi _{\mathfrak {p}}(\phi ))$ is the fixed imaginary quadratic field K. We present upper bounds for Πϕ(K;d) obtained by two different approaches, inspired by similar ones for elliptic curves. The first approach, inspired by the work of Serre, is to consider the image of Frobenius in a mixed Galois representation associated to K and to the Drinfeld module ϕ. The second approach, inspired by the work of Cojocaru, Fouvry and Murty, is based on an application of the square sieve. The bounds obtained with the first method are better, but depend on the fixed quadratic imaginary field K. In our application of the second approach, we improve the results of Cojocaru, Murty and Fouvry by considering projective Galois representations.
On the unramified spectrum of spherical varieties over p-adic fields
Authors: Sakellaridis Yiannis
Published: July 2008

The description of irreducible representations of a group G can be seen as a problem in harmonic analysis; namely, decomposing a suitable space of functions on G into irreducibles for the action of G×G by left and right multiplication. For a split p-adic reductive group G over a local non-archimedean field, unramified irreducible smooth representations are in bijection with semisimple conjugacy classes in the ‘Langlands dual’ group. We generalize this description to an arbitrary spherical variety X of G as follows. Irreducible unramified quotients of the space $C_c^\infty (X)$ are in natural ‘almost bijection’ with a number of copies of AX*/WX, the quotient of a complex torus by the ‘little Weyl group’ of X. This leads to a description of the Hecke module of unramified vectors (a weak analog of geometric results of Gaitsgory and Nadler), and an understanding of the phenomenon that representations ‘distinguished’ by certain subgroups are functorial lifts. In the course of the proof, rationality properties of spherical varieties are examined and a new interpretation is given for the action, defined by Knop, of the Weyl group on the set of Borel orbits.
Transversality theorem in o-minimal structures
Authors: Loi Ta Lê
Published: July 2008

In this paper we present Thom’s transversality theorem in o-minimal structures (a generalization of semialgebraic and subanalytic geometry). There are no restrictions on the differentiability class and the dimensions of manifolds involved in comparison withthe general case.
On the Collapse Structure of an Attached Cavity on a Three-Dimensional Hydrofoil
Authors: Foeth Evert-Jan , van Terwisga Tom , van Doorne Cas
Published: July 2008

A three-dimensional twisted hydrofoil with an attached cavitaty closely related to propellers was observed with a high-speed camera at the University of Delft Cavitation Tunnel. Reentrant flow coming from the sides of the cavity aimed at the center plane—termed side-entrant flow—collided in the closure region of the cavity, pinching off a part of the sheet resulting in a periodic shedding. The collapse of the remainder of the sheet appears to be a mixing layer at the location of the colliding reentrant flows. Collision of side-entrant jets in the closure region of a cavity is identified as a second shedding mechanism, in addition to reentrant flow impinging the sheet interface at the leading edge.
Development of a Computer Simulation Model for Blowing Glass Containers
Authors: Giannopapa C. G.
Published: July 2008

In glass container manufacturing (e.g., production of glass bottles and jars) an important process step is the blowing of the final product. This process is fast and is characterized by large deformations and the interaction of a hot glass fluid that gets into contact with a colder metal, the mould. The objective of this paper is to create a robust finite-element model to be used for industrial purposes that accurately captures the blowing step of glass containers. The model should be able to correctly represent the flow of glass and the energy exchange during the process. For tracking the geometry of the deforming inner and outer interface of glass, level set technique is applied on structured and unstructured fixed mesh. At each time step the coupled problem of flow and energy exchange is solved by the model. Here the flow problem is only solved for the domain enclosed by the mould, whereas in the energy calculations, the mould domain is also taken into account in the computations. For all the calculations the material parameters (like viscosity) are based on the glass position, i.e., the position of the level sets. The velocity distribution, as found from this solution procedure, is then used to update the two level sets by means of solving a convection equation. A reinitialization algorithm is applied after each time step in order to let the level sets reattain the property of being a signed distance function. The model is validated by several examples focusing on both the overall behavior (such as conservation of mass and energy) and the local behavior of the flow (such as glass-mould contact) and temperature distributions for different mesh size, time step, level set settings and material parameters.
Thermal and Structural Deformations During Diamond Turning of Rotationally Symmetric Structured Surfaces
Authors: Rakuff Stefan , Beaudet Paul
Published: July 2008

Diamond turning of microstructures on the surface of large cylindrical workpieces has become important with advances made in roll-to-roll manufacturing processes of optical films, drag reduction films, microfluidic devices, and organic electronic components. Micromachined cylindrical workpieces are used as production masters in various printing, embossing, and coating processes. The microstructures machined in this study were 18μm in height and had a pitch of 35μm. These dimensions required control of the location of the single crystal diamond cutting tool that was used for machining to submicrometer levels. The significant error sources identified in the machining process were thermal effects and deflections of the structural loop of the diamond turning machine (DTM) that led to registration errors of the cutting tool between consecutive passes. Environmental temperature variation errors (ETVEs) were measured and modeled as a function of long-term ambient temperature fluctuations. Also studied was the mechanical compliance of the structural loop of the DTM. The height adjustable tool stack and aerostatic spindle were identified as the most compliant components. The cutting forces for radius and V-shaped diamond cutting tools at various depths of cut were measured using the known compliance of the aerostatic bearing to predict workpiece deflections.
Support Vector Fuzzy Adaptive Network in the Modeling of Material Removal Rate in Rotary Ultrasonic Machining
Authors: Shen Judong , Pei Z. J. , Lee E. S.
Published: July 2008

Rotary ultrasonic machining (RUM) is one of the cost-effective machining methods for machining difficult to process material. It is a hybrid machining process that combines the material removal mechanisms of diamond grinding with ultrasonic machining. However, due to the lack of understanding of the mechanisms of these operations, models for these machining processes are difficult to establish. In this paper, the support vector fuzzy adaptive network (SVFAN), a parameter free nonlinear regression technique, is used to model the material removal rate in RUM. The SVFAN retains the advantages of both the fuzzy adaptive networks and the support vector machines. The former possesses the linguistic representation ability and the latter is a very effective learning machine. The results are compared with that obtained by the use of fuzzy adaptive network and it is shown that the combined approach is a more effective algorithm for the modeling of complex manufacturing processes.
Investigating Reliability of Variable Blank Holder Force Control in Sheet Drawing Under Process Uncertainties
Authors: Zhang Wenfeng , Shivpuri Rajiv
Published: July 2008

The blank holder force (BHF), which regulates the amount of metal drawn into the die cavity, has been used effectively to draw defect-free sheet parts. It has been shown that a properly designed variable BHF profile can provide greater drawability as compared to constant BHF. Extensive research has been carried out in the past to determine this optimal profile. However, these deterministic efforts neglect the sensitivity of this optimal BHF design to unintended process variations inherent in sheet forming. This paper investigates the reliability of optimal variable BHF in the presence of process uncertainties by minimizing the magnitude of wrinkling and fracture defects under probabilistic constraints. To demonstrate the efficacy of this approach, it analyzes the conical cup drawing of an aluminum killed deep-drawing quality steel under process uncertainties including sheet thickness, punch speed, interface friction at the punch surface, and interface friction at the die surface. The results show that probabilistic design improves the yield (probability of good parts) to 99.98% as compared to the 48.04% yield realized by the traditional deterministic design. In addition, Monte Carlo simulations verify that the probabilistic design handles the uncertainties better due to its inherent robustness. This is primarily due to the design moving away from the process constraints and at the same time balancing the probability of failure between the two failure modes.
Experimental Investigation of Springback Variation in Forming of High Strength Steels
Authors: Chen Peng , Koç Muammer , Wenner Michael L.
Published: July 2008

The use of high strength steels (HSSs) in automotive body structures is a prominent method of reducing vehicle weight as an alternative to use of aluminum and magnesium alloys. However, parts made of HSSs demonstrate more springback than parts made of mild steels do. Moreover, variations in the incoming material, friction, and other process conditions cause variations in the springback characteristics, which prevent the practical applicability of the springback prediction and compensation techniques. Consequently, it leads to amplified variations and quality issues during assembly of the stamped components. The objective of this study is to investigate and gain an understanding of the variation of springback in the forming of HSSs. Two sets of experiments were conducted to analyze the influence of the material property (dual-phase steels from different suppliers), lubrication, and blank holder pressure on the springback variation. The experimental results showed that the variation in the incoming blank material is the most important factor. In summary, the thicker the blank is, the less the springback variation. On the other hand, blanks without a coating show less springback variation. The application of lubricant helps us to reduce springback variation, although it actually increases the springback itself. The more uniform the friction condition, the less the springback variation. The influence of blank holder pressure on the springback variation is not distinguishable from the system-level noise in our experiment.
Numerical Simulation of Direct Metal Laser Sintering of Single-Component Powder on Top of Sintered Layers
Authors: Xiao Bin , Zhang Yuwen
Published: July 2008

A three-dimensional model describing melting and resolidification of direct metal laser sintering of loose powders on top of sintered layers with a moving Gaussian laser beam is developed. Natural convection in the liquid pool driven by buoyancy and Marangoni effects is taken into account. A temperature transforming model is employed to model melting and resolidification in the laser sintering process. The continuity, momentum, and energy equations are solved using a finite volume method. The effects of dominant processing parameters including number of the existing sintered layers underneath, laser scanning velocity, and initial porosity on the sintering process are investigated.
Tool Feasibility Analysis for Fixture Assembly Planning
Authors: Kang Xiumei , Peng Qingjin
Published: July 2008

Tool feasibility is a critical issue for generating a complete fixture assembly plan to reduce production setup time. Previous fixture design systems rarely consider the assembly tool feasibility. Current methods of assembly tool feasibility analysis mainly depend on simulation-based or user-interactive approaches, which rely on users’ judgment. This paper presents a new approach to tool feasibility analysis for fixture assembly planning. The fixture workspace around a tool is represented by a newly defined global accessibility sphere with depth of a truncated half-line. The assembly tools are modeled as five articulated parts to fully describe the tool characteristics. Tool feasibility analysis is executed to verify assembly tools’ feasibility applied on a fastener. In particular, both tool motion and tool placement constraints during tool applications are integrated into the tool geometric reasoning. The example demonstrates the fast computing speed and intuitive simulation of several assembly tools applied in fixture assembly.
Simulation of a New Solid State Joining Process Using Single-Shoulder Two-Pin Tool
Authors: Mukherjee S. , Ghosh A. K.
Published: July 2008

In friction stir welding (FSW) process, heat is generated by friction between the tool and the workpiece. The conventional tool design employs a cylindrical shoulder with a single profiled pin. A new process has been designed that uses two-pin tool under the same shoulder to increase shear deformation within workpiece that can enhance local heating where joining occurs. The design employs two closely spaced pins rotating in the same direction within the workpiece under a separately controlled shoulder. The process is distinctly different from the Twin-stir™ variant of FSW in which each pin performs an independent function and non-interacting. Prior to gathering considerable experimental data with new equipment, a fully coupled themomechanical three-dimensional finite element model has been developed to compare the existing single-pin technology with new technology of friction driven stitch welding process. The computational results for the two-pin tool show considerable shearing along the joining interface, enhanced local heating, and a reduced reaction force on the pins, which are described in this paper. The results of this study indicate that the two-pin tool design with a separate shoulder, with the same direction of pin rotation, can be a superior design in comparison to the conventional single-pin FSW tool and could minimize damage to tool material.
A Localization Algorithm for Improving Fabrication of Curved Hull Plates in Shipbuilding
Authors: Park Jung Seo , Shin Jong Gye , Hyun Chung Min , Doh Young Chil , Ko Kwang Hee
Published: July 2008

In this paper, a localization method is proposed for improving the curved plate fabrication process. In the curved plate forming, checking the similarity of a manufactured plate to a CAD model is a critical step, which can be done by aligning the manufactured plate to the CAD model. Although there exist several localization methods, they may not be suitable for the curved plate forming since they do not consider production efficiency (the shortest cutting length for trimming margin) for the subsequent assembly process. Therefore, in this work, a constraint for minimizing the cutting length is introduced in the localization scheme and an algorithm is proposed to handle the problem. A manufactured plate is measured and a constraint is imposed on the reference points of a CAD model and the measured points to limit the direction of the movement of the measured points in the solution process. Through this algorithm, the CAD model and the measured points are aligned such that the shortest cutting length is obtained. After the alignment, the cutting lines are computed for marking on the manufactured plate. Various curved plates taken from the real ship manufacturing process are used to demonstrate the performance of the proposed algorithm.
Ultrasonic Sensor for High Temperature Gas Filled Vessels
Authors: Sandman J. S. , Tittmann B. R.
Published: July 2008

The focus of this paper is an Ultrasonic Position Indication System (UPIS) that is capable of determining one-dimensional target location in a high temperature steel-container with gaseous medium. The combination of the very high acoustical impedance of steel (45.4MRayl) and the very low impedance of air (0.0004MRayl) causes extremely high-energy losses upon transmission. In addition to the energy loss, propagation through a steel plate produces many internal reflections in the plate. The strategy of this investigation was to develop a self-contained ultrasonic transducer that is capable of replacing a small portion of a high temperature-pressure boundary. In building such a transducer, sufficient acoustic matching layers for the steel-gas interface, a mechanically and acoustically competent housing, a sufficient piezoelectric element, and backing materials are all developed and tested. The results include a successful housing design, high-temperature acoustic matching layers, and subsequent successful waveforms. Target location through 9.6” (24.5cm) of ambient air was successful, with a steel pressure boundary 0.4566” (1.1598cm) thick, and using one matching layer. In addition to the experimental results, this investigation includes numerical simulations. Sample waveforms were predicted one-dimensionally with the Mason model using MatLab, and two-dimensionally with a Coupled Acoustic Piezoelectric Finite Element Method (CAPA) program. The Mason model program predicts waveform changes as the wave travels through various interfaces. CAPA is a finite element program that predicts waveforms based on the equations for ultrasonic wave propagation.
Stress Indices Evaluation of Piping Ratchet Fatigue From Extreme Dynamic Loading
Authors: Ibrahim Zakaria N.
Published: July 2008

Piping systems are subjected to a wide range of anticipated and/or postulated dynamic loading. With the exception of steam propelled water slug flow transient, thee dynamic loading result in response reversals that have not the characteristics of sustained loading. Dynamic test to failure did not exhibit the classical collapse catastrophic failure mode. The dynamic response reversals exhibited gradual ratcheting and fatigue crack growth that concurrently lead to the failure. The stress intensity classifications provided by the piping stress indices, in conjunction with Edmunds and Beer or Bree Plate ratchet models, are utilized to estimate the accumulated ratchet strains in the pipe component. The allowed maximum accumulating local ratchet strain is set arbitrarily to 10%, which is less than half of the measured ratchet strains found in the dynamic tests. Simple criteria for evaluating the degradation level in the piping components subjected to the concurrent ratchet-fatigue failure mechanisms are presented. The approach utilizes a methodology similar to that used in the creep-fatigue interaction damage provided in the ASME Section III, Subsection NH, Appendix-T. Replacing the creep strain term by that of the ratchet strain, and replacing the bilinear damage function with the square root function, yields the ratchet-fatigue degradation criteria formulations presented in this paper. Considerations for the plastic buckling due to the accumulated compressive ratchet strains as well as the primary component of the piping thermal expansion stress due to elastic follow-up are also presented.
Symmetric and Non-Symmetric Formulations for Fluid-Structure Interaction Problems: Reference Test Cases for Numerical Developments in a Commercial Finite Element Code
Authors: Sigrist Jean-Franc¸ois
Published: July 2008

The present paper deals with numerical analysis of fluid-structure interaction problems with commercial finite element codes. The various fluid-structure formulations are today well known from a theoretical point of view, but their application to the dynamic analysis of industrial problems with spectral methods can not be performed with all available codes. The present study exposes a developing process currently undertaken in order to integrate symmetric FSI formulation within the commercial finite element code Ansys. This process is carried out in several steps which are detailed here: first, on overview of the existing fluid-structure formulations is exposed with the view to comparing various finite element codes. Then, coupled symmetric and non-symmetric formulations are recalled on two general FSI problems (elasto-acoustic and hydro-elastic problems) and applied on a generic reference test case. Numerical integration of the presented methods is performed on the Ansys code in the following direction: free surface condition for sloshing mode in pressure formulation, harmonic axi-symmetric pressure fluid formulation for coupled axi-symmetric calculations, general symmetric coupled formulation in u,p,φ (for elasto-acoustic problems with fluid free surface without sloshing) and u,p,η (hydro-elastic problems with fluid free surface with sloshing) formulations. Elementary validations of the implemented methods are proposed by comparing Ansys numerical results to calculations results obtained with a finite element code developed by DCN Propulsion, and presented in the paper. All the developments will be available in future release of the Ansys code in the coming years for the benefit of the Ansys users’ community.
Modal Analysis of a Nuclear Reactor With Fluid-Structure Interaction: Influence of Fluid Compressibility
Authors: Sigrist Jean-Franc¸ois , Broc Daniel
Published: July 2008

The present paper deals with the modal analysis of a nuclear with fluid-structure interaction effects. In a previous study, added mass and added stiffness effects due to fluid-structure interaction were modeled and studied. A dynamic analysis was performed for a seismic excitation, i.e. in the low frequency range. The present study deals with high frequency analysis, i.e. taking into account compressibility effects in the fluid problem. Elasto-acoustic coupling phenomena are studied and described in the industrial case. The elasto-acoustic coupled problem is formulated using the displacement/pressure-displacement potential coupled formulation which yields symmetric matrices. A modal analysis is first performed on the fluid problem alone, with a calculation of acoustic eigenfrequencies and the corresponding modal masses. A modal analysis is then performed for the coupled fluid-structure problem in the case of an incompressible fluid and a compressible fluid at standard pressure and temperature conditions and for a compressible fluid at the operating pressure and temperature conditions. Elasto-coupling effects are then highlighted and discussed.
The Influence of the Bauschinger Effect on the Combined Stress Intensity Factors of Multiple Longitudinally Coplanar Cracks in Autofrettaged Pressurized Cylinders
Authors: Levy C. , Perl M. , Kotagiri S.
Published: July 2008

The influence of the Bauschinger Effect (BE) on the three dimensional, Mode I, Combined Stress Intensity Factor (SIF) distributions for arrays of longitudinal coplanar, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. The combined SIFs, KIN, that depend on both the “realistic” - Bauschinger Effect Dependent Autofrettage (BEDA) and “ideal” - Bauschinger Effect Independent Autofrettage (BEIA) are obtained and compared for crack to wall thickness, a/t = 0.01–0.25; crack ellipticity, a/c = 0.5–1.5; crack spacing ratio, 2c/d = 0.25–0.75; and autofrettage level, e = 30, 60 and 100%. The 3-D analysis is performed via the finite element (FE) method and the submodeling technique, employing singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are simulated using an equivalent temperature field. The KIN is found to vary along the crack front with the maximum determined by the crack ellipticity, crack depth and crack spacing ratio. For a partially autofrettaged cylinder, the influence of the BE on the combined SIF, KIN, is considerably reduced as the level of overstrain becomes smaller. For some cases, when comparing like crack distributions, the KIN values obtained from the BEDA model are found to be as much as 100% higher than the KIN values that are computed using the BEIA model. A pressurized thick-walled cylinder with BEDA can be most dangerous when small cracks have small spacing ratio, i.e., when the cracks are farther apart. As crack length increases, or, for increased spacing ratio when the spacing between cracks is smaller, the SIFs increase. Though the differences in the BEDA SIF, KIA, between e = 100% and 60% are small (7–15%, in most cases), the increased level of autofrettage produces a 23–30% decrease in the combined SIF values, KIN. In certain cases, the BEIA model implies an infinite fatigue life, whereas the BEDA model for the same parameters implies a finite life. Therefore, it is important to perform a full 3-D analysis to determine the real life cycle of the pressurized cylinder for materials that exhibit the Bauschinger effect.
Stress Classification Using the R-Node Method
Authors: Fanous Ihab F. Z. , Seshadri R.
Published: July 2008

The ASME Code Section III and Section VIII (Division 2) provide stress classification guidelines to interpret the results of a linear elastic finite element analysis. These guidelines enable the splitting of the generated stresses into primary, secondary and peak. The code gives some examples to explain the suggested procedures. Although these examples may reflect a wide range of applications in the field of pressure vessel and piping, the guidelines are difficult to use with complex geometries. In this paper, the r-node method is used to investigate the primary stresses and their locations in both simple and complex geometries. The method is verified using the plane beam and axisymmetric torispherical head. Also, the method is applied to analyze 3D straight and oblique nozzle modeled using both solid and shell elements. The results of the analysis of the oblique nozzle are compared with recently published experimental data.
Prediction of Fracture Stresses of High Pressure Gas Cylinders Containing Crack Like Flaws
Authors: Rana Mahendra D. , Rawls George B.
Published: July 2008

Full scale tests were conducted on high pressure gas cylinders containing crack-like flaws. The cylinders were then pressurized to destruction and the membrane hoop stress at failure in the cylinder wall was calculated from the failure pressure. Mechanical properties including tensile and fracture data were obtained on specimens representing the heats of the tested cylinders. Analyses were performed to predict the failure stresses using several methods available in the open literature. This paper presents the results of the predicted and measured fracture stresses.