bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ausbreitungsverhalten mikrostrukturell kurzer Ermüdungsrisse – experimentelle Charakterisierung und mechanismenorientierte Simulation
Authors: Christ H.‐J. , Düber O. , Knobbe H. , Fritzen C.‐P. , Krupp U. , Künkler B. , Köster P. 
Published: October 2008

AbstractIn diesem Beitrag werden Ergebnisse eines interdisziplinären Forschungsprojekts präsentiert, welches die Autoren während der letzten sieben Jahren durchgeführt haben. Thema des Projekts war die experimentelle Charakterisierung und mechanismenbasierte Simulation mikrostrukturell kurzer Risse. Es wurden Ermüdungsexperimente an dem austenitisch‐ferritischen Duplexstahl X2 CrNiMoN 22–5‐3 durchgeführt. Dabei konnte gezeigt werden, dass mikrostrukturelle Eigenschaften wie Korngröße, Phasenverteilung oder lokale Fließspannung des Korns, in welchem sich die Rissspitze befindet, den wachsenden Riss beeinflussen. Auf Basis der experimentellen Ergebnisse wurde ein mechanismenorientiertes Modell entwickelt, welches das Ausbreitungsverhalten kurzer Risse physikalisch begründet beschreiben kann. Mikrostrukturelle Parameter wie Körngröße, Kornverteilung, Kornorientierung usw. sind im Modell berücksichtigt, indem gemessene Werte einer virtuell erzeugten Mikrostruktur zugewiesen werden. Die Simulation findet dann in dieser virtuellen Mikrostruktur statt. Der Vergleich zwischen beobachteten und simulierten Werten zeigt eine ausgezeichnete Übereinstimmung.
Current developments and trends on structural durability
Authors: Bacher‐Höchst M. , Berger C. , Sonsino C. M. , Vormwald M. 
Published: October 2008

AbstractBasic approaches for assessment of Structural Durability are outlined in principle. Some of their limits in actual application fields and new solutions are shown. Multiaxial Fatigue remains as to be treated very carefully. The superposition of damaging processes known as “Very High Cycle Fatigue” and “Corrosion Fatigue” might be a key for assessment of components at very high load cycles.
Short crack approach for multiaxial fatigue assessment
Authors: Vormwald M. , Hertel O. 
Published: October 2008

AbstractA significant part of the fatigue life is spent during short crack growth. Therefore, modelling of short fatigue crack growth offers an opportunity to improve the accuracy of numerical life assessment. Besides stating some general remarks on the short crack approach itself and on multiaxial fatigue criteria, a short crack growth based fatigue life prediction approach for multiaxial non‐proportional loading is presented. This approach accounts for the geometrical size effect by considering the geometry correction functions for semi‐elliptical surface cracks in inhomogeneous gradient stress fields. The geometrical size effect is becoming significant for notch radii smaller than four times the defined technical crack size. Additionally, life influencing factors due to the statistical size effect have been taken into account. The comparison of calculated and experimentally observed fatigue lives of shouldered shafts made of S460N with notch radii of 0.2 to 4.0 mm under non‐proportional tension and torsion loading yields a satisfying accuracy.
Crack growth predictions using a strip‐yield model for variable‐amplitude and spectrum loading
Authors: Ziegler B. , Yamada Y. , Newman J. C. 
Published: October 2008

AbstractFatigue‐crack‐growth tests were conducted on compact, C(T), specimens made of D16Cz aluminum alloy. Constant‐amplitude tests were conducted over a range of stress ratios (R = Pmin/Pmax = 0.1 to 0.75). Comparisons were made between test data from middle‐crack tension, M(T), specimens from the literature and C(T) specimens. A crack‐closure analysis was used to collapse the rate data from both specimen types into a fairly narrow band over many orders of magnitude in rates using proper constraint factors. Constraint factors were established from single‐spike overload and constant‐amplitude tests. The life‐prediction code, FASTRAN, which is based on the strip‐yield‐model concept, was used to calculate the crack‐length‐against‐cycles under constant‐amplitude (CA) loading and the single‐spike overload (OL) tests; and to predict crack growth under variable‐amplitude (VA) loading on M(T) specimens and simulated aircraft loading spectrum tests on both specimen types. The calculated crack‐growth lives under CA and the OL tests were generally within ±20 % of the test results, the predicted crack‐growth lives for the VA and Mini‐Falstaff tests on the M(T) specimens were short by 30 to 45 %, while the Mini‐Falstaff+ results on the C(T) specimens were within 10 %. Issues on the crack‐starter notch effects under spectrum loading are discussed, and recommendations are suggested on avoiding these notch effects.
Variable amplitude fatigue of autofrettaged diesel injection parts
Authors: Thumser R. , Bergmann J.W. , Herz E. , Hertel O. , Vormwald M. 
Published: October 2008

AbstractExperimental and analytical investigations of constant and variable amplitude fatigue life of not autofrettaged and autofrettaged components have been performed. In variable amplitude loading the new standardisedCOmmon‐RAil‐Load sequenceCORALhas been used as well as two‐level‐tests with small cycles at high mean stresses interrupted by large cycles for the evaluation of load sequence effects. The results of the two level tests show that small cycles with amplitudes far below the fatigue limit cause fatigue damage. Life calculations have been performed according tothe nominal stress approach with S‐N‐curves and improved Miner’s Rule,linear‐elastic fracture mechanics with 3D‐weight functions,elastic‐plastic fracture mechanics applying an extended strip yield‐model, andexplicit 3D‐FE‐simulation of fatigue crack growth with predefined crack fronts.All approaches are appropriate for predicting realistic variable amplitude lives. From a practical point of view the explicit 3D‐FE‐simulation of fatigue crack growth is too time‐consuming. However, such simulations show that the approaches based on linear‐elastic fracture mechanics and elastic‐plastic fracture mechanics with extended strip yield‐model capture the essential physics of fatigue crack growth in a realistic way.
Fatigue assessment of seam welds of automotive components by local stress approaches
Authors: Bruder T. , Störzel K. , Baumgartner J. 
Published: October 2008

AbstractIn the present paper a method is described for the fatigue assessment of multi‐axial loaded welded joints in structures made from thin steel sheets. The focus is on seam welds under non‐proportional loading, assuming a constant angular phase shift between cycles leading to stress components acting at the seam welds. Fatigue analyses are using a local stress approach based on stresses derived by Theory of Elasticity. Furthermore, potentials of considering statistical size effects in order to analyse weld start and end points are outlined.
Size effects in the fatigue behavior of welded steel tubular bridge joints
Authors: Nussbaumer A. , Costa Borges L. A. 
Published: October 2008

AbstractTubular space trusses for bridge applications use thick‐walled tubes. The reduction in fatigue resistance due to geometrical size effects is thus an important issue. In order to carry out a thorough study, both fatigue tests on large‐scale specimens and advanced 3D crack propagation modelling were carried out at ICOM/EPFL. The study is limited to circular hollow sections (CHS) K‐joints. An alternate current potential drop (ACPD) system is used to measure crack depth on nodes of the tested truss specimens. The results obtained from the tests are given in the paper in terms of S‐N data, crack depth versus number of cycles and deduced crack propagation rates. The numerical model was developed using the dual boundary elements method (DBEM), software BEASY™, and was validated with fatigue tests data. The stress intensity factors (SIF) along the doubly curved crack front at different crack depths were obtained. With this model, a parametric study investigates the influence of geometry, size and load case on fatigue life. The results of both proportional and non‐proportional sizing effects on fatigue strength are presented. The paper shows that size effects (proportional and non‐proportional) can be expressed as a function of the non‐dimensional parameters and chord thickness.
Structural durability criteria for commercial vehicle components from the self strengthening cast ausferrite nodular iron EN‐GJS‐800–8 (ADI) in comparison to the ferritic EN‐GJS‐400–15
Authors: Sonsino C. M. , Zinke R. , Heinrietz A. , Heim R. , Hanselka H. , Streicher M. 
Published: October 2008

AbstractThe structural durability of safety components in the chassis comprises not only the fatigue behaviour under cyclic variable amplitude service loading, but also its interaction with prestrains caused by special events and the rupture behaviour under impact loading due to misuse . From this background, the structural durability behaviour of Panhard rods made from ferritic cast nodular iron EN‐GJS‐400–15 was compared with the behaviour of rods made from the austempered EN‐GJS‐800–8. The components investigated, Panhard rods and cast plugs, made from the austempered material revealed a higher impact resistance than the components made from the ferritic cast nodular iron. Due to their ausferrite microstructure, Panhard rods made from EN‐GJS‐800–8 display a significantly superior fatigue strength behaviour, especially under spectrum loading, and offer a potential for lightweight design. Prestrains do not affect the fatigue behaviour under variable amplitude loading and the plastic deformation of the component under impact loading can be increased by appropriate design reducing the stiffness in the shaft area and achieving a weight reduction by 15 %.
Material and fatigue life models for thermo‐mechanical loaded components
Authors: Eichlseder W. , Winter G. , Köberl H. 
Published: October 2008

AbstractToday, specific material data, mainly from static material tests, are not sufficient to design parts of a product to assess lifetime behaviour, especially when local complex loading occurs like low cycle fatigue (LCF) and thermo mechanical fatigue (TMF). In this work, specimen tests are carried out under LCF and TMF loading with different materials, where mechanical and thermal properties are considered. The investigated materials are an aluminium alloy, cast iron, copper alloy and nickel. The TMF tests are performed by using a TMF test rig, designed by the Chair of Mechanical Engineering (AMB). The results of these tests allow a description of the material behaviour depending on the mechanical and thermal boundary conditions. Commercial Software for Finite Element Analysis (FEA) enables a fit with the test results to calculate stress and strain values for different loading conditions. These results are the input data for the final lifetime calculation. A number of approaches are given to determine the lifetime for the investigated materials. Finally, a special modified energy method – “unified energy approach” – is presented and compared with conventional approaches.
Tumor suppressor and oncogene actions of TGFβ1 occur early in skin carcinogenesis and are mediated by Smad3
Authors: Bae Dong‐Soon , Blazanin Nicholas , Licata Mathew , Lee Jessica , Glick Adam B. 
Published: October 2008

AbstractInteractions between TGFβ1 and ras signaling pathways play an important role in cancer development. Here we show that in primary mouse keratinocytes, v‐rasHa does not block the early biochemical events of TGFβ1 signal transduction but does alter global TGFβ1 mediated gene expression in a gene specific manner. Expression of Smad3 dependent TGFβ1 early response genes and the TGFβ1 cytostatic gene expression response were not altered by v‐rasHa consistent with an intact TGFβ1 growth arrest. However, TGFβ1 and v‐rasHa cause significant alteration in genes regulating matrix remodeling as the TGFβ1 induction of extracellular matrix genes was blocked by v‐rasHa but specific matrix proteases associated with cancer progression were elevated. Smad3 deletion in keratinocytes repressed normal differentiation maker expression and caused expression of Keratin 8 a simple epithelial keratin and marker of malignant conversion. Smad3 was required for the TGFβ1 cytostatic response in v‐rasHa keratinocytes, but also for protease induction, keratinocyte attachment and migration. These results show that pro‐oncogenic activities of TGFβ1 can occur early in carcinogenesis before loss of its tumor suppressive function and that selective regulation rather than complete inactivation of Smad3 function may be crucial for tumor progression. © 2008 Wiley‐Liss, Inc.
A randomized controlled trial of movement strategies compared with exercise for people with Parkinson's disease
Authors: Morris Meg E. , Iansek Robert , Kirkwood Beth 
Published: October 2008

AbstractThis randomized controlled clinical trial was conducted to compare the effects of movement rehabilitation strategies and exercise therapy in hospitalized patients with idiopathic Parkinson's disease. Participants were randomly assigned to a group that received movement strategy training or musculoskeletal exercises during 2 consecutive weeks of hospitalization. The primary outcome was disability as measured by the Unified Parkinson's Disease Rating Scale, UPDRS (motor and ADL components). Secondary outcomes were balance, walking speed, endurance, and quality of life. Assessments were carried out by blinded testers at baseline, after the 2 weeks of treatment and 3 months after discharge. The movement strategy group showed improvements on several outcome measures from admission to discharge, including the UPDRS, 10 m walk, 2 minute walk, balance, and PDQ39. However, from discharge to follow up there was significant regression in performance on the 2 minute walk and PDQ39. For the exercise group, quality of life improved significantly during inpatient hospitalization and this was retained at follow‐up. Inpatient rehabilitation produces short term reductions in disability and improvements in quality of life in people with Parkinson's disease. © 2008 Movement Disorder Society
EPR studies of the dynamics and phase behaviour of dithiadiazolyl radicals derived from mesogenic precursors
Authors: Rawson Jeremy M. , Clarke Caroline S. , Bruce Duncan W. 
Published: October 2008

AbstractA series of liquid‐crystalline materials based on 4‐substituted cyanobiphenyls, RC6H4C6H4CN (R = C5H11, C6H13, C7H15, C8H17 and C12H25, commonly referred to as 5CB, 6CB, 7CB, 8CB and 12CB, respectively) were functionalised to give the corresponding dithiadiazolyl organic radicals RC6H4C6H4CNSSN• (compounds 1•, 2•, 3•, 4• and 5•, respectively). EPR spectra of n‐C12H25C6H4C6H4CNSSN• (5•) reveal that it adopts a dimeric diamagnetic structure in the solid state with a small number of paramagnetic defect sites. Variable temperature electron paramagnetic resonance (EPR) studies reveal a thermally activated rotation about the molecular long axis at temperatures above 314 K. The energy barrier to rotation about the phenylene–dithiadiazolyl bond was estimated as 25 kJ mol−1 using density functional theory (DFT). At elevated temperatures thermal annealing was also observed, quenching the sample's paramagnetism. Copyright © 2008 John Wiley & Sons, Ltd.
Dynamic evacuation routes for personnel on a naval ship
Authors: Pérez‐Villalonga Francisco , Salmerón Javier , Wood Kevin 
Published: October 2008

AbstractWe propose a dynamic escape route system for emergency evacuation of a naval ship. The system employs signals that adapt to the causative contingency and the crew's physical distribution about the ship. A mixed‐integer nonlinear programming model, with underlying network structure, optimizes the evacuation process. The network's nodes represent compartments, closures (e.g., doors and hatches) and intersections, while arcs represent various types of passageways. The objective function integrates two potentially conflicting factors: average evacuation time and the watertight and airtight integrity of the ship after evacuation. A heuristic solves the model approximately using a sequence of mixed‐integer linear approximating problems. Using data for a Spanish frigate, with standard static routes specified by the ship's designers, computational tests show that the dynamic system can reduce average evacuation times, nearly 23%, and can improve a combined measure of ship integrity by up to 50%. In addition, plausible design changes to the frigate yield further, substantial improvements. Published 2008 Wiley Periodicals, Inc. Naval Research Logistics 2008
A new outranking‐based approach for assigning alternatives to ordered classes
Authors: Köksalan Murat , Mousseau Vincent , Özpeynirci Özgür , Özpeynirci Selin Bilgin 
Published: October 2008

AbstractWe consider the problem of assigning alternatives evaluated on several criteria into ordered categories C1,C2,…,Cp. This problem is known as the multi‐criteria sorting problem and arises in many situations such as classifying countries into different risk levels based on economical and socio‐political criteria, evaluating credit applications of bank customers. We are interested in sorting methods that are grounded on the construction of outranking relations. Among these, the Electre Tri method requires defining multidimensional profiles that represent the “frontier” separating consecutive categories Ch and Ch+1, and assigns an alternative to categories according to how it compares to each of the profiles. The explicit specification of the profiles of consecutive categories can be difficult for decision makers. We develop a new outranking based sorting method that does not require the explicit definition of profiles. We instead require the decision maker to assign a subset of reference alternatives to the categories. To assign the remaining alternatives, each such alternative is compared to reference alternatives, and assigned to categories accordingly. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009
Optimizing the US Navy's combat logistics force
Authors: Brown Gerald G. , Carlyle W. Matthew 
Published: October 2008

AbstractWe study how changes to the composition and employment of the US Navy combat logistic force (CLF) influence our ability to supply our navy worldwide. The CLF consists of about 30 special transport ships that carry ship and aircraft fuel, ordnance, dry stores, and food, and deliver these to client combatant ships underway, making it possible for our naval forces to operate at sea for extended periods. We have modeled CLF operations to evaluate a number of transforming initiatives that simplify its operation while supporting an even larger number of client ships for a greater variety of missions. Our input is an employment schedule for navy battle groups of ships operating worldwide, extending over a planning horizon of 90–180 days. We show how we use optimization to advise how to sustain these ships. We have used this model to evaluate new CLF ship designs, advise what number of ships in a new ship class would be needed, test concepts for forward at‐sea logistics bases in lieu of conventional ports, demonstrate the effects of changes to operating policy, and generally try to show whether and how the CLF can support planned naval operations. Published 2008 Wiley Periodicals, Inc. Naval Research Logistics 2008
Noncooperative cost spanning tree games with budget restrictions
Authors: Bergantiños Gustavo , Lorenzo Leticia 
Published: October 2008

AbstractWe extend the noncooperative game associated with the cost spanning tree problem introduced by Bergantiños and Lorenzo (Math Method Oper Res 59(2004), 393–403) to situations where agents have budget restrictions. We study the Nash equilibria, subgame perfect Nash equilibria, and strong Nash equilibria of this game. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2008
A selective newsvendor approach to order management
Authors: Taaffe Kevin , Romeijn Edwin , Tirumalasetty Deepak 
Published: October 2008

AbstractConsider a supplier offering a product to several potential demand sources, each with a unique revenue, size, and probability that it will materialize. Given a long procurement lead time, the supplier must choose the orders to pursue and the total quantity to procure prior to the selling season. We model this as a selective newsvendor problem of maximizing profits where the total (random) demand is given by the set of pursued orders. Given that the dimensionality of a mixed‐integer linear programming formulation of the problem increases exponentially with the number of potential orders, we develop both a tailored exact algorithm based on the L‐shaped method for two‐stage stochastic programming as well as a heuristic method. We also extend our solution approach to account for piecewise‐linear cost and revenue functions as well as a multiperiod setting. Extensive experimentation indicates that our exact approach rapidly finds optimal solutions with three times as many orders as a state‐of‐the‐art commercial solver. In addition, our heuristic approach provides average gaps of less than 1% for the largest problems that can be solved exactly. Observing that the gaps decrease as problem size grows, we expect the heuristic approach to work well for large problem instances. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2008
Dynamic inventory management with cash flow constraints
Authors: Chao Xiuli , Chen Jia , Wang Shouyang 
Published: October 2008

AbstractIn this article, we consider a classic dynamic inventory control problem of a self‐financing retailer who periodically replenishes its stock from a supplier and sells it to the market. The replenishment decisions of the retailer are constrained by cash flow, which is updated periodically following purchasing and sales in each period. Excess demand in each period is lost when insufficient inventory is in stock. The retailer's objective is to maximize its expected terminal wealth at the end of the planning horizon. We characterize the optimal inventory control policy and present a simple algorithm for computing the optimal policies for each period. Conditions are identified under which the optimal control policies are identical across periods. We also present comparative statics results on the optimal control policy. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2008
Ventricular cerebrospinal fluid lactate is increased in chronic fatigue syndrome compared with generalized anxiety disorder: an in vivo 3.0 T 1H MRS imaging study
Authors: Mathew Sanjay J. , Mao Xiangling , Keegan Kathryn A. , Levine Susan M. , Smith Eric L. P. , Heier Linda A. , Otcheretko Viktor , Coplan Jeremy D. , Shungu Dikoma C. 
Published: October 2008

AbstractChronic fatigue syndrome (CFS) is a controversial diagnosis because of the lack of biomarkers for the illness and its symptom overlap with neuropsychiatric, infectious, and rheumatological disorders. We compared lateral ventricular volumes derived from tissue‐segmented T1‐weighted volumetric MRI data and cerebrospinal fluid (CSF) lactate concentrations measured by proton MRS imaging (1H MRSI) in 16 subjects with CFS (modified US Centers for Disease Control and Prevention criteria) with those in 14 patients with generalized anxiety disorder (GAD) and in 15 healthy volunteers, matched group‐wise for age, sex, body mass index, handedness, and IQ. Mean lateral ventricular lactate concentrations measured by 1H MRSI in CFS were increased by 297% compared with those in GAD (P < 0.001) and by 348% compared with those in healthy volunteers (P < 0.001), even after controlling for ventricular volume, which did not differ significantly between the groups. Regression analysis revealed that diagnosis accounted for 43% of the variance in ventricular lactate. CFS is associated with significantly raised concentrations of ventricular lactate, potentially consistent with recent evidence of decreased cortical blood flow, secondary mitochondrial dysfunction, and/or oxidative stress abnormalities in the disorder. Copyright © 2008 John Wiley & Sons, Ltd.