The statistical strength of nonlocality proofs
Dam, van W.; Gill, R.D.; Grünwald, P.D.
2005-01-01
There exist numerous proofs of Bell's theorem, stating that quantum mechanics is incompatible with local realistic theories of nature. Here the strength of such nonlocality proofs is defined in terms of the amount of evidence against local realism provided by the corresponding experiments.
Microstructural investigation of variations in the proof strength of Nimonic PE16
International Nuclear Information System (INIS)
Riley, B.F.; Wilson, E.G.; Jones, A.R.
1987-01-01
Nimonic PE16 shows a correlation of stress rupture behaviour after irradiation with proof strength. Proof testing of material from bars from several casts yielded a relationship (Hall-Petch) between the peak-aged proof stress and grain size -1/2 but the scatter in proof stress values at a given grain size merited further microstructural study. Transmission electron microscopy revealed that high proof stress material contained dislocation densities consistent with material which had received 1 to 2% cold work, verified by examination of lightly prestrained tensile specimens. Ageing to peak strength induced partial recovery but some variability in proof stress remained. Variations in γ' size and composition having been eliminated, the scatter in proof stress values was attributed to variable cold work induced by the commercial bar straightening process. (Author)
Flexural strength of proof-tested and neutron-irradiated silicon carbide
Price, R. J.; Hopkins, G. R.
1982-08-01
Proof testing before service is a valuable method for ensuring the reliability of ceramic structures. Silicon carbide has been proposed as a very low activation first-wall and blanket structural material for fusion devices, where it would experience a high flux of fast neutrons. Strips of three types of silicon carbide were loaded in four-point bending to a stress sufficient to break about a third of the specimens. Groups of 16 survivors were irradiated to 2 × 10 26n/ m2 ( E>0.05 MeV) at 740°C and bend tested to failure. The strength distribution of chemically vapor-deposited silicon carbide (Texas Instruments) was virtually unchanged by irradiation. The mean strength of sintered silicon carbide (Carborundum Alpha) was reduced 34% by irradiation, while the Weibull modulus and the truncated strength distribution characteristic of proof-tested material were retained. Irradiation reduced the mean strength of reaction-bonded silicon carbide (Norton NC-430) by 58%, and the spread in strength values was increased. We conclude that for the chemically vapor-deposited and the sintered silicon carbide the benefits of proof testing to eliminate low strength material are retained after high neutron exposures.
Assessment of ECISS draft standard for derivation of high temperature proof strength values
Energy Technology Data Exchange (ETDEWEB)
Linde, L.; Sandstroem, R.
1996-03-01
New European material standards are under development and modern data evaluation techniques must be able to supply these standards with accurate design values. A draft standard for the derivation of high temperature proof strength values has been proposed. This standard (EDS) has been used to calculate strength values for six steels; one unalloyed steel, one 12 % Cr steel and four austenitic stainless steels. Although large data sets were available, it was not possible to satisfy the requirement in the EDS of 80 % temperature coverage in the proof strength data for several steels. It suggests that temperature coverage specified in the EDS is unrealistically high. Due to the limited number of heats satisfying the temperature coverage requirements for each steel, the statistical error in the derived values exceeds 10-20 % which must be considered as unacceptably high. Instead it is recommended that the full data sets are used irrespective of temperature coverage. The variation of proof strength values represented by the analysed heats did not cover the corresponding variation in the larger data set available. This was the case even for the steel where 16 heats satisfied the temperature coverage requirement. Thus a limited number of heats can not be expected to be a good representation of more complete data sets. This has the consequence that absolute strength values can not be derived without access to a standardised proof strength at room temperature. Two derivation methods investigated in this report are both based on the ISO 2605/III procedure for proof strength assessments at elevated temperature. Method I and II use an essentially temperature independent and temperature dependent reduction term respectively. The methods have been assessed by the same data sets for the six steels. One or both methods gave satisfactory results for most of the investigated steels. Presented results are based on work carried out in ECISS TC22 WG1. 17 refs, 20 figs, 7 tabs.
Proof of fatigue strength of ferritic and austenitic nuclear components
Energy Technology Data Exchange (ETDEWEB)
Roos, E.; Herter, K.H.; Schuler, X.; Weissenberg, T. [Materialpruefungsanstalt, Univ. Stuttgart (Germany)
2009-07-01
For the construction, design and operation of nuclear components and systems the appropriate technical codes and standards provide material data, detailed stress analysis procedures and a design philosophy which guarantees a reliable behaviour of the structural components throughout the specified lifetime. Especially for cyclic stress evaluation the different codes and standards provide different fatigue analyses procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. For the fatigue design curves used as limiting criteria the influence of different factors like e.g., environment, surface finish and temperature must be taken into consideration in an appropriate way. Fatigue tests were performed with low alloy steels as well as with Nb- and Ti-stabilized German austenitic stainless steels in air and simulated high temperature boiling water reactor environment. The experimental results are compared and valuated with the mean data curves in air as well as with mean data curves under high temperature water environment published in the international literature. (orig.)
Li, Hui; Yang, Jin; Li, Pan; Lan, Tianqing; Peng, Lincai
2017-03-15
We proposed a green and facile method to fabricate superhydrophobic paper in this study, which is layer-by-layer (LBL) deposition of TiO 2 nanoparticles/sodium alginate (ALG) multilayers on paper surface followed by an adsorption treatment of colloidal carnauba wax. The formation of TiO 2 /ALG multilayers on paper surface was characterized by X-ray photoelectron spectroscopy (XPS), zeta potential measurement, scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The wetting property of modified paper was investigated by water contact angle (WCA) measurement. Moreover, the modified paper tensile strength has been evaluated. The results showed that WCA of paper modified with a wax-treated (TiO 2 /ALG) 3.5 multilayer reached up to 151.5°, and this obtained superhydrophobic paper exhibited improved tensile strength (increased by 4.1% compared to the pristine paper), excellent moisture-proofing property and high strength stability under high relative humidity condition, which might has a great potential for use in the liquid paper packaging and moisture-proof paper packaging. Copyright © 2016 Elsevier Ltd. All rights reserved.
A proof of the Bekenstein bound for any strength of gravity through holography
International Nuclear Information System (INIS)
Pesci, Alessandro
2010-01-01
The universal entropy bound of Bekenstein is considered at any strength of a gravitational interaction. A proof of it is given, provided the considered general-relativistic spacetimes allow for a meaningful and unequivocal definition of the quantities which participate in the bound (such as system energy and radius). This is done assuming as a starting point that, for assigned statistical-mechanical local conditions, a lower-limiting scale l* to system size definitely exists, it being required by holography through its semiclassical formulation as given by the generalized covariant entropy bound. An attempt is also made to draw some possible general consequences of the l* assumption with regard to the proliferation of species problem and to the viscosity to entropy density ratio. Concerning the latter, various fluids are considered including systems potentially relevant, to some extent, to the quark-gluon plasma case.
Character strengths, social anxiety, and physiological stress reactivity
Directory of Open Access Journals (Sweden)
Tingting Li
2017-05-01
Full Text Available In this paper, the effects of character strengths on the physiological reactivity to social anxiety induced by the Trier Social Stress Task were reported. On the basis of their scores in the Chinese Virtues Questionnaire, 30 college students were assigned to either high- (n = 15 or low-character-strength (n = 15 groups. Their psychological stress and physiological data across three laboratory stages (namely, baseline, stress exposure, and post-stress were collected. Results indicated that individuals with high character strengths exhibited rapid cardiovascular recovery from baseline to post-stress even if high- and low-character-strength groups showed similar patterns of cardiovascular arousal in response to the stress at baseline and stress exposure. These results prove that character strengths are stress-defense factors that allow for psychological and physiological adaptation to stress.
The Inclusion of Arbitrary Load Histories in the Strength Decay Model for Stress Rupture
Reeder, James R.
2014-01-01
Stress rupture is a failure mechanism where failures can occur after a period of time, even though the material has seen no increase in load. Carbon/epoxy composite materials have demonstrated the stress rupture failure mechanism. In a previous work, a model was proposed for stress rupture of composite overwrap pressure vessels (COPVs) and similar composite structures based on strength degradation. However, the original model was limited to constant load periods (holds) at constant load. The model was expanded in this paper to address arbitrary loading histories and specifically the inclusions of ramp loadings up to holds and back down. The broadening of the model allows for failures on loading to be treated as any other failure that may occur during testing instead of having to be treated as a special case. The inclusion of ramps can also influence the length of the "safe period" following proof loading that was previously predicted by the model. No stress rupture failures are predicted in a safe period because time is required for strength to decay from above the proof level to the lower level of loading. Although the model can predict failures during the ramp periods, no closed-form solution for the failure times could be derived. Therefore, two suggested solution techniques were proposed. Finally, the model was used to design an experiment that could detect the difference between the strength decay model and a commonly used model for stress rupture. Although these types of models are necessary to help guide experiments for stress rupture, only experimental evidence will determine how well the model may predict actual material response. If the model can be shown to be accurate, current proof loading requirements may result in predicted safe periods as long as 10(13) years. COPVs design requirements for stress rupture may then be relaxed, allowing more efficient designs, while still maintaining an acceptable level of safety.
Stable crack growth during over stressing or proof testing of pressure vessels
International Nuclear Information System (INIS)
Njo, D.H.
1985-07-01
In an earlier study several years ago an attempt has been made by a study group in Switzerland formed by representatives of utilities, manufacturers, inspection agency and the licensing authority to evaluate systematically the advantages and disadvantages of a proof test for a reactor pressure vessel (RPV) taking into account the different aspects involved. In this study, the present day practice in the requirements regarding proof testing in several countries with nuclear power plants were assessed. Using the method of fracture mechanics, taking into account the proof test conditions and material behaviour at hand, qualified quantitative statements were then sought for. One of the important findings of the study was that a sufficiently accurate determination of stable crack growth (SCG) during proof testing is a necessary precondition for a qualified quantitative statement. At that time this requirement could not be met. The aim of the present exercise of collecting available information on SCG was twofold: to get an overview of the present day requirements on pre-service and in-service proof testing of reactor pressure vessels in different countries with NPPs; to collect data on stable crack growth due to over stressing during proof tests to be used in the quantitative assessment, using fracture mechanics methods, and the potential benefit, if any, of proof tests. In the framework of the present study, the originally stipulated aims could not be achieved. It turned out to be a very complex and difficult problem, where various important aspects are little known and could not be assessed without further comprehensive theoretical and experimental investigations
The Influence of Perceived Stress on Cortical Reactivity: A Proof-Of-Principle Study.
Directory of Open Access Journals (Sweden)
Rosan Luijcks
Full Text Available The aim of this study was to investigate how perceived stress may affect electroencephalographical (EEG activity in a stress paradigm in a sample of 76 healthy participants. EEG activity was analyzed using multilevel modeling, allowing estimation of nested effects (EEG time segments within subjects. The stress paradigm consisted of a 3-minute pre-stimulus stress period and a 2-minute post-stimulus phase. At t=3 minutes, a single electrical stimulus was delivered. Participants were unaware of the precise moment of stimulus delivery and its intensity level. In the EEG time course of alpha activity, a stronger increase was observed during the post-stimulus period as compared to the pre-stimulus period. An opposite time course effect was apparent for gamma activity. Both effects were in line with a priori expectations and support the validity of this experimental EEG-stress paradigm. Secondly, we investigated whether interaction effects of stress and coping, as measured with the Perceived Stress Scale-10 questionnaire (PSS-10, could be demonstrated. A higher perceived stress score was accompanied by a greater increase in delta- and theta-activity during the post-stimulus phase, compared to low scores. In contrast, low coping capacity was associated with a stronger decrease in slow beta, fast beta and gamma activity during the post-stimulus phase. The results of the present article may be interpreted as proof-of-principle that EEG stress-related activity depends on the level of subjectively reported perceived stress. The inclusion of psychosocial variables measuring coping styles as well as stress-related personality aspects permits further examination of the interconnection between mind and body and may inform on the process of transformation from acute to chronic stress.
International Nuclear Information System (INIS)
Matsuoka, Saburo
2004-01-01
Stress corrosion cracking (SCC) occurs in shrouds and piping made of low carbon austenitic stainless steels at nuclear power plants. A work-hardened layer is considered to be one of the probable causes for this occurrence. The maximum Vickers hardness measured at the work-hardened layer is 400 HV. It is important to determine the yield strength and tensile strength of the work-hardened layer in the investigation on the causes of SCC. However, the tensile specimen cannot be obtained since the thickness of the work-hardened layer is as mall as several hundred μm, therefore, it is useful if we can estimate these strengths from its Vickers hardness. Consequently, we investigated the relationships between Vickers hardness versus yield strength and tensile strength using the results obtained on various steels in a series of Fatigue Data Sheets published by the National Institute for Materials Science and results newly obtained on a parent material and rolled materials (reduction of area: 10 - 50%, maximum hardness: 350 HV) for a low carbon stainless steel. The results showed that (1) the relationship between the 0.2% proof stress and the Vickers hardness can be described by a single straight line regardless of strength, structure, and rolling ratio, however, (2) the tensile strength is not correlated with the Vickers hardness, and the austenitic stainless steel in particular shows characteristics different from those of other steels. (author)
Statistical considerations of graphite strength for assessing design allowable stresses
International Nuclear Information System (INIS)
Ishihara, M.; Mogi, H.; Ioka, I.; Arai, T.; Oku, T.
1987-01-01
Several aspects of statistics need to be considered to determine design allowable stresses for graphite structures. These include: 1) Statistical variation of graphite material strength. 2) Uncertainty of calculated stress. 3) Reliability (survival probability) required from operational and safety performance of graphite structures. This paper deals with some statistical considerations of structural graphite for assessing design allowable stress. Firstly, probability distribution functions of tensile and compressive strengths are investigated on experimental Very High Temperature candidated graphites. Normal, logarithmic normal and Weibull distribution functions are compared in terms of coefficient of correlation to measured strength data. This leads to the adaptation of normal distribution function. Then, the relation between factor of safety and fracture probability is discussed on the following items: 1) As the graphite strength is more variable than metalic material's strength, the effect of strength variation to the fracture probability is evaluated. 2) Fracture probability depending on survival probability of 99 ∼ 99.9 (%) with confidence level of 90 ∼ 95 (%) is discussed. 3) As the material properties used in the design analysis are usually the mean values of their variation, the additional effect of these variations on the fracture probability is discussed. Finally, the way to assure the minimum ultimate strength with required survival probability with confidence level is discussed in view of statistical treatment of the strength data from varying sample numbers in a material acceptance test. (author)
Relaxation of stress and density, strength (fatigue)
Gräfe, Wolfgang
2015-01-01
This treatment of ""Time-Dependent Mechanical Properties of Solids"" beginswith a phenomenological description of the transport of some unspecifiedentity. It is assumed that the transport is caused by mechanical stresses ortemperature fields. Using these assumptions, it is possible to deduceformulae for a theoretically based description of several phenomena withoutreferring to any specific process or entity. These theoretical results thenprovide the tools for performing methodologically better scientific work andfor a better analysis of data in the practical application of materials. Bypublish
Strength conditions for the elastic structures with a stress error
Matveev, A. D.
2017-10-01
As is known, the constraints (strength conditions) for the safety factor of elastic structures and design details of a particular class, e.g. aviation structures are established, i.e. the safety factor values of such structures should be within the given range. It should be noted that the constraints are set for the safety factors corresponding to analytical (exact) solutions of elasticity problems represented for the structures. Developing the analytical solutions for most structures, especially irregular shape ones, is associated with great difficulties. Approximate approaches to solve the elasticity problems, e.g. the technical theories of deformation of homogeneous and composite plates, beams and shells, are widely used for a great number of structures. Technical theories based on the hypotheses give rise to approximate (technical) solutions with an irreducible error, with the exact value being difficult to be determined. In static calculations of the structural strength with a specified small range for the safety factors application of technical (by the Theory of Strength of Materials) solutions is difficult. However, there are some numerical methods for developing the approximate solutions of elasticity problems with arbitrarily small errors. In present paper, the adjusted reference (specified) strength conditions for the structural safety factor corresponding to approximate solution of the elasticity problem have been proposed. The stress error estimation is taken into account using the proposed strength conditions. It has been shown that, to fulfill the specified strength conditions for the safety factor of the given structure corresponding to an exact solution, the adjusted strength conditions for the structural safety factor corresponding to an approximate solution are required. The stress error estimation which is the basis for developing the adjusted strength conditions has been determined for the specified strength conditions. The adjusted strength
Broersma, M; Koops, E A; Vroomen, P C; Van der Hoeven, J H; Aleman, A; Leenders, K L; Maurits, N M; van Beilen, M
2015-05-01
Therapeutic options are limited in functional neurological paresis disorder. Earlier intervention studies did not control for a placebo effect, hampering assessment of effectivity. A proof-of-principle investigation was conducted into the therapeutic potential of repetitive transcranial magnetic stimulation (rTMS), using a single-blind two-period placebo-controlled cross-over design. Eleven patients received active 15 Hz rTMS over the contralateral motor cortex (hand area), in two periods of 5 days, for 30 min once a day at 80% of resting motor threshold, with a train length of 2 s and an intertrain interval of 4 s. Eight of these eleven patients were also included in the placebo treatment condition. Primary outcome measure was change in muscle strength as measured by dynamometry after treatment. Secondary outcome measure was the subjective change in muscle strength after treatment. In patients who received both treatments, active rTMS induced a significantly larger median increase in objectively measured muscle strength (24%) compared to placebo rTMS (6%; P difference due to treatment, i.e. patients did not perceive these objectively measured motor improvements (P = 0.40). Our findings suggest that rTMS by itself can potentially improve muscle weakness in functional neurological paresis disorder. Whereas patients' muscle strength increased as measured with dynamometry, patients did not report increased functioning of the affected hand, subjectively. The results may indicate that decreased muscle strength is not the core symptom and that rTMS should be added to behavioral approaches in functional neurological paresis. © 2015 EAN.
Effect of internal stress on the strength of PZT ceramics
Energy Technology Data Exchange (ETDEWEB)
Tai, Weon Pil; Yun, Yeo Bum; Kim, Song Hee [Kangwon National Univ., Chunchon (Korea, Republic of)
1996-01-01
The aim of this study is to investigate the change of bending strength and fatigue strength in the unpolled and poled Pb(Zr, Ti)O ferroelectrics of tetragonal, morphotropic phase boundary (MPB) and rhombohedral composition in terms of internal stress which is measured by XRD method. Before poling treatment the highest bending strength was found in rhombohedral composition. After poling treatment, the bending strength decreased in all compositions but it decreased most remarkably in tetragonal composition. The most prominent decrease of bending strength after poling treatment in tetragonal was attributed to the occurrence of microcracks due to high anisotropic internal stress around grain boundary which was induced by domain alignment toward electric field direction in the microstructure having tetragonality. The decrease of bending strength after poling in MPB and rhombohedral composition was not due to the occurrence of microcracks but to the increase in tensile internal stress perpendicular to the direction of crack propagation by domain alignment. Fatigue strength was higher before poling treatment than after poling treatment for various compositions. 13 refs., 2 tabs., 5 figs.
design of ceramic membrane supports: permeability, tensile strength and stress
Biesheuvel, Pieter Maarten; Biesheuvel, P.M.; Verweij, H.
1999-01-01
A membrane support provides mechanical strength to a membrane top layer to withstand the stress induced by the pressure difference applied over the entire membrane and must simultaneously have a low resistance to the filtrate flow. In this paper an experimental and a theoretical approach toward the
Strength and residual stress of Mg-PSZ after grinding
van den Berg, P.H.J.; With, de G.
1993-01-01
The influence of grinding with two grinding wheels, differing mainly in diamond-grain size, on the properties of MgO-partially stabilized ZrO2 ceramics (Mg-PSZ) was examd. The residual stress, the amt. of monoclinic zirconia, and the strength of the material were detd. From these measurements, depth
Stress corrosion in high-strength aluminum alloys
Dorward, R. C.; Hasse, K. R.
1980-01-01
Report describes results of stress-corrosion tests on aluminum alloys 7075, 7475, 7050, and 7049. Tests compare performance of original stress-corrosion-resistant (SCR) aluminum, 7075, with newer, higher-strength SCR alloys. Alloys 7050 and 7049 are found superior in short-transverse cross-corrosion resistance to older 7075 alloy; all alloys are subject to self-loading effect caused by wedging of corrosion products in cracks. Effect causes cracks to continue to grow, even at very-low externally applied loads.
Machine learning methods to predict child posttraumatic stress: a proof of concept study.
Saxe, Glenn N; Ma, Sisi; Ren, Jiwen; Aliferis, Constantin
2017-07-10
The care of traumatized children would benefit significantly from accurate predictive models for Posttraumatic Stress Disorder (PTSD), using information available around the time of trauma. Machine Learning (ML) computational methods have yielded strong results in recent applications across many diseases and data types, yet they have not been previously applied to childhood PTSD. Since these methods have not been applied to this complex and debilitating disorder, there is a great deal that remains to be learned about their application. The first step is to prove the concept: Can ML methods - as applied in other fields - produce predictive classification models for childhood PTSD? Additionally, we seek to determine if specific variables can be identified - from the aforementioned predictive classification models - with putative causal relations to PTSD. ML predictive classification methods - with causal discovery feature selection - were applied to a data set of 163 children hospitalized with an injury and PTSD was determined three months after hospital discharge. At the time of hospitalization, 105 risk factor variables were collected spanning a range of biopsychosocial domains. Seven percent of subjects had a high level of PTSD symptoms. A predictive classification model was discovered with significant predictive accuracy. A predictive model constructed based on subsets of potentially causally relevant features achieves similar predictivity compared to the best predictive model constructed with all variables. Causal Discovery feature selection methods identified 58 variables of which 10 were identified as most stable. In this first proof-of-concept application of ML methods to predict childhood Posttraumatic Stress we were able to determine both predictive classification models for childhood PTSD and identify several causal variables. This set of techniques has great potential for enhancing the methodological toolkit in the field and future studies should seek to
Stress-strength reliability for general bivariate distributions
Directory of Open Access Journals (Sweden)
Alaa H. Abdel-Hamid
2016-10-01
Full Text Available An expression for the stress-strength reliability R=P(X1
Bond strength and stress measurements in thermal barrier coatings
Energy Technology Data Exchange (ETDEWEB)
Gell, M.; Jordan, E. [Univ. of Connecticut, Storrs, CT (United States)
1995-10-01
Thermal barrier coatings have been used extensively in aircraft gas turbines for more than 15 years to insulate combustors and turbine vanes from the hot gas stream. Plasma sprayed thermal barrier coatings (TBCs) provide metal temperature reductions as much as 300{degrees}F, with improvements in durability of two times or more being achieved. The introduction of TBCs deposited by electron beam physical vapor deposition (EB-PVD) processes in the last five years has provided a major improvement in durability and also enabled TBCs to be applied to turbine blades for improved engine performance. To meet the aggressive Advanced Turbine Systems goals for efficiency, durability and the environment, it will be necessary to employ thermal barrier coatings on turbine airfoils and other hot section components. For The successful application of TBCs to ATS engines with 2600{degrees}F turbine inlet temperatures and required component lives 10 times greater than those for aircraft gas turbine engines, it is necessary to develop quantitative assessment techniques for TBC coating integrity with time and cycles in ATS engines. Thermal barrier coatings in production today consist of a metallic bond coat, such as an MCrAlY overlay coating or a platinum aluminide (Pt-Al) diffusion coating. During heat treatment, both these coatings form a thin, tightly adherent alumina (Al{sub 2}O{sub 3}) film. Failure of TBC coatings in engine service occurs by spallation of the ceramic coating at or near the bond coat to alumina or the alumina to zirconia bonds. Thus, it is the initial strength of these bonds and the stresses at the bond plane, and their changes with engine exposure, that determines coating durability. The purpose of this program is to provide, for the first time, a quantitative assessment of TBC bond strength and bond plane stresses as a function of engine time and cycles.
CSIR Research Space (South Africa)
Theyse, HL
2006-09-01
Full Text Available to the ratio of the imposed stress over the shear strength of the material. Conventionally, the shear strength of the material was characterised with the Mohr-Coulomb shear strength parameters. This paper further develops a recent yield strength model...
A dependent stress-strength interference model based on mixed copula function
Energy Technology Data Exchange (ETDEWEB)
Gao, Jian Xiong; An, Zong Wen; Liu, Bo [School of Mechatronics Engineering, Lanzhou University of Technology, Lanzhou (China)
2016-10-15
In the traditional Stress-strength interference (SSI) model, stress and strength must satisfy the basic assumption of mutual independence. However, a complex dependence between stress and strength exists in practical engineering. To evaluate structural reliability under the case that stress and strength are dependent, a mixed copula function is introduced to a new dependent SSI model. This model can fully characterize the dependence between stress and strength. The residual square sum method and genetic algorithm are also used to estimate the unknown parameters of the model. Finally, the validity of the proposed model is demonstrated via a practical case. Results show that traditional SSI model ignoring the dependence between stress and strength more easily overestimates product reliability than the new dependent SSI model.
Duan, Wenjie
2016-11-01
This study used a two-wave longitudinal research design to explore the role of individual strengths, including interpersonal strength, intellectual strength, and temperance strength, in affecting the mental health of stressed college students. A total of 404 stressed Chinese college students were screened to participate in this 12-month longitudinal study. At the beginning of the study (Time 1), students who had not experienced stressful events within the last 12 months were invited to assess their strengths, psychological well-being, and psychological symptoms. After 12 months (Time 2), 404 students who reported stressful experiences completed the scales again and were retained for the final analyses. Academics-related stressors were the most endorsed life events among college students, whose states of mental health showed downward trends from Time 1 to Time 2. Three strengths had weak to modest correlations to mental health at both Time 1 and Time 2. Although the additional variances of mental health explained by the three strengths were very modest, the mediational roles of the strengths were identified. The perceived stress completely mediated the relationship between the strengths and the psychological symptoms and partly mediated the relationship between the strengths and psychological well-being. Individual strengths may function as a defense against perceived stress and are protective factors of mental health. These strengths maintain mental health by enhancing the psychological well-being and reducing the psychological symptoms of individuals.
A discrete stress-strength interference model based on universal generating function
International Nuclear Information System (INIS)
An Zongwen; Huang Hongzhong; Liu Yu
2008-01-01
Continuous stress-strength interference (SSI) model regards stress and strength as continuous random variables with known probability density function. This, to some extent, results in a limitation of its application. In this paper, stress and strength are treated as discrete random variables, and a discrete SSI model is presented by using the universal generating function (UGF) method. Finally, case studies demonstrate the validity of the discrete model in a variety of circumstances, in which stress and strength can be represented by continuous random variables, discrete random variables, or two groups of experimental data
Compressive strength evolution of thermally-stressed Saint Maximin limestone.
Farquharson, J.; Griffiths, L.; Baud, P.; Wadsworth, F. B.; Heap, M. J.
2017-12-01
The Saint Maximin quarry (Oise, France) opened in the early 1600s, and its limestone has been used extensively as masonry stone, particularly during the classical era of Parisian architecture from the 17th century onwards. Its widespread use has been due to a combination of its regional availability, its high workability, and its aesthetic appeal. Notable buildings completed using this material include sections of the Place de la Concorde and the Louvre in Paris. More recently, however, it has seen increasing use in the construction of large private residences throughout the United States as well as extensions to private institutions such as Stanford University. For any large building, fire hazard can be a substantial concern, especially in tectonically active areas where catastrophic fires may arise following large-magnitude earthquakes. Typically, house fires burn at temperatures of around 600 °C ( 1000 F). Given the ubiquity of this geomaterial as a building stone, it is important to ascertain the influence of heating on the strength of Saint Maximin limestone (SML), and in turn the structural stability of the buildings it is used in. We performed a series of compressive tests and permeability measurements on samples of SML to determine its strength evolution in response to heating to incrementally higher temperatures. We observe that the uniaxial compressive strength of SML decreases from >12 MPa at room temperature to 400 °C). We anticipate that this substantial weakening is in part a result of thermal microcracking, whereby changes in temperature induce thermal stresses due to a mismatch in thermal expansion between the constituent grains. This mechanism is compounded by the volumetric increase of quartz through its alpha - beta transition at 573 °C, and by the thermal decomposition of calcite. To track the formation of thermal microcracks, we monitor acoustic emissions, a common proxy for microcracking, during the heating of an SML sample. The
The relationships of character strengths with coping, work-related stress, and job satisfaction.
Harzer, Claudia; Ruch, Willibald
2015-01-01
Personality traits have often been highlighted to relate to how people cope with stressful events. The present paper focuses on character strengths as positive personality traits and examines two basic assumptions that were derived from a core characteristic of character strengths (i.e., to determine how individuals deal with adversities): (1) character strengths correlate with coping and (2) buffer the effects of work-related stress on job satisfaction. Two different samples (i.e., a mixed sample representing various occupations [N = 214] and a nurses sample [N = 175]) filled in measures for character strengths, coping, work-related stress, and job satisfaction. As expected, intellectual, emotional, and interpersonal strengths were related to coping. Interpersonal strengths played a greater role for coping among nurses, as interactions with others are an essential part of their workday. Furthermore, intellectual strengths partially mediated the negative effect of work-related stress on job satisfaction. These findings open a new field for research on the role of personality in coping with work-related stress. Character strengths are trainable personal characteristics, and therefore valuable resources to improve coping with work-related stress and to decrease the negative effects of stress. Further research is needed to investigate this assumed causality.
The relationships of character strengths with coping, work-related stress, and job satisfaction
Directory of Open Access Journals (Sweden)
Claudia eHarzer
2015-02-01
Full Text Available Personality traits have often been highlighted to relate to how people cope with stressful events. The present paper focuses on character strengths as positive personality traits and examines two basic assumptions that were derived from a core characteristic of character strengths (i.e., to determine how individuals deal with adversities: (1 Character strengths correlate with coping and (2 buffer the effects of work-related stress on job satisfaction. Two different samples (i.e., a mixed sample representing various occupations [N = 214] and a nurses sample [N = 175] filled in measures for character strengths, coping, work-related stress, and job satisfaction. As expected, intellectual, emotional, and interpersonal strengths were related to coping. Interpersonal strengths played a greater role for coping among nurses, as interactions with others are an essential part of their workday. Furthermore, intellectual strengths partially mediated the negative effect of work-related stress on job satisfaction. These findings open a new field for research on the role of personality in coping with work-related stress. Character strengths are trainable personal characteristics, and therefore valuable resources to improve coping with work-related stress and to decrease the negative effects of stress. Further research is needed to investigate this assumed causality.
International Nuclear Information System (INIS)
Aleskerova, S.A.; Pakharyan, V.A.
1978-01-01
Effect of corrosion and mechanical factors of preliminary stress corrosion of a metal in its fatigue strength, has been investigated. Smooth cylindrical samples of 20 steel have been tested. Preliminary corrosion under stress has been carried out under natural sea conditions. It is shown that mechanical stresses in the case of preliminary corrosion affect fatigue strength of low-carbon steels, decreasing the range of limited durability and fatigue limit. This effect increases with the increase of stress level and agressivity of corrosive medium
Konovodov, V. V.; Valentov, A. V.; Kukhar, I. S.; Retyunskiy, O. Yu; Baraksanov, A. S.
2016-08-01
The work proposes the algorithm to calculate strength under alternating stresses using the developed methodology of building the diagram of limiting stresses. The overall safety factor is defined by the suggested formula. Strength calculations of components working under alternating stresses in the great majority of cases are conducted as the checking ones. It is primarily explained by the fact that the overall fatigue strength reduction factor (Kσg or Kτg) can only be chosen approximately during the component design as the engineer at this stage of work has just the approximate idea on the component size and shape.
Directory of Open Access Journals (Sweden)
Weiguo Li
2012-01-01
Full Text Available A thermodamage strength theoretical model taking into account the effect of residual stress was established and applied to each temperature phase based on the study of effects of various physical mechanisms on the fracture strength of ultrahigh-temperature ceramics. The effects of SiC particle size, crack size, and SiC particle volume fraction on strength corresponding to different temperatures were studied in detail. This study showed that when flaw size is not large, the bigger SiC particle size results in the greater effect of tensile residual stress in the matrix grains on strength reduction, and this prediction coincides with experimental results; and the residual stress and the combined effort of particle size and crack size play important roles in controlling material strength.
Energy Technology Data Exchange (ETDEWEB)
De la Camp, H.J.; Feser, G.; Hofmann, A.; Wolf, B.; Schmidt, H. [TUeV Sueddeutschland Bau und Betrieb GmbH, Muenchen (Germany); Herforth, H.E.; Juengling, K.H.; Schmidt, W. [TUeV Anlagentechnik GmbH, Berlin-Schoeneberg (Germany). Unternehmensgruppe TUeV Rheinland/Berlin-Brandenburg
2002-01-01
The report is aimed at collecting and documenting the state of the art and the extensive know how of experts and pipeline operators with regard to judging the structural integrity of pipelines. In order to assess the actual mechanical strength of pipelines based on measurement results obtained by inspection pigs, guidance is given for future processing, which eventually can be used as a basis for an industry standard. A literature study of the commercially available types of inspection pigs describes and synoptically lists the respective pros and cons. In essence the report comprises besides check lists of operating data for the pipeline and the pig runs mainly the evaluation of defects and respective calculating procedures. Included are recommendations regarding maintenance planning, verification of defects as well as repetition of pig runs. (orig.) [German] Ziel des Berichtes ist die Erfassung und Dokumentation zum derzeitigen Stand der Technik und des vorhandenen umfangreichen Know-how von Sachverstaendigen und Pipelinebetreibern auf dem Gebiet der sicherheitstechnischen Beurteilung von Pipelines. Fuer den Festigkeitsnachweis von Pipelines aufgrund der Messergebnisse von Pruefmolchen wurde ein Leitfaden als Basis fuer die zukuenftige Vorgehensweise erstellt, der eventuell die Grundlage eines normativen Regelwerkes bilden kann. In einer Literaturstudie wurden die auf dem Markt befindlichen Pruefmolchtypen zusammenfassend beschrieben und ihre Vor- und Nachteile tabellarisch gegenuebergestellt und bewertet. Neben der Erstellung von Checklisten fuer notwendige Daten zum Betrieb der Pipeline und der Molchlaeufe bildet die Fehlerbewertung mit entsprechenden Berechnungsverfahren den Hauptteil dieses Berichtes. Hinweise zur Instandhaltungsplanung (Fehlerverifikation und Molchlaufwiederholung) werden gegeben. (orig.)
Bone geometry, strength, and muscle size in runners with a history of stress fracture.
Popp, Kristin L; Hughes, Julie M; Smock, Amanda J; Novotny, Susan A; Stovitz, Steven D; Koehler, Scott M; Petit, Moira A
2009-12-01
Our primary aim was to explore differences in estimates of tibial bone strength, in female runners with and without a history of stress fractures. Our secondary aim was to explore differences in bone geometry, volumetric density, and muscle size that may explain bone strength outcomes. A total of 39 competitive distance runners aged 18-35 yr, with (SFX, n = 19) or without (NSFX, n = 20) a history of stress fracture were recruited for this cross-sectional study. Peripheral quantitative computed tomography (XCT 3000; Orthometrix, White Plains, NY) was used to assess volumetric bone mineral density (vBMD, mg x mm(-3)), bone area (ToA, mm(2)), and estimated compressive bone strength (bone strength index (BSI) = ToA x total volumetric density (ToD(2))) at the distal tibia (4%). Total (ToA, mm(2)) and cortical (CoA, mm(2)) bone area, cortical vBMD, and estimated bending strength (strength-strain index (SSIp), mm(3)) were measured at the 15%, 25%, 33%, 45%, 50%, and 66% sites. Muscle cross-sectional area (MCSA) was measured at the 50% and 66% sites. Participants in the SFX group had significantly smaller (7%-8%) CoA at the 45%, 50%, and 66% sites (P stress fracture. However, the lower strength was appropriate for the smaller muscle size, suggesting that interventions to reduce stress fracture risk might be aimed at improving muscle size and strength.
Stress Analysis and Strength Prediction of Adhesively Bonded Composite Joints
National Research Council Canada - National Science Library
Rastogi, Naveen
1998-01-01
.... Further, the submodeling technique available in the commercial finite element package ABAQUS is explored to study the three-dimensional stress field in the vicinity of joint edges and debond cracks...
International Nuclear Information System (INIS)
Krätschmer, D.; Roos, E.; Schuler, X.; Herter, K.-H.
2012-01-01
For the construction, design and operation of nuclear components and systems the appropriate technical codes and standards provide detailed analysis procedures which guarantee a reliable behaviour of the structural components throughout the specified lifetime. Especially for cyclic stress evaluation the different codes and standards provide different fatigue analyses procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. To consider effects of light water reactor coolant environments, new design curves included in report NUREG/CR-6909 for austenitic stainless steels and for low alloy steels have been presented. For the usage of these new design curves an environmental fatigue correction factor for incorporating environmental effects has to be calculated and used. The application of this environmental correction factor to a fatigue analysis of a nozzle with transient stratification loads, derived by in-service monitoring, has been performed. The results are used to compare with calculated usage factors, based on design curves without taking environmental effects particularly into account. - Highlights: ► We model an nozzle for fatigue analysis und mechanical and thermal loading conditions. ► A simplified as well as a general elastic–plastic fatigue analysis considering environmental effects is performed. ► The influence of different factors calculating the environmental factor F en are shown. ► The presented numerical evaluation methodology allows the consideration of all relevant parameters to assess lifetime.
Residual stress in a thick section high strength T-butt weld
International Nuclear Information System (INIS)
Pearce, S.V.; Linton, V.M.; Oliver, E.C.
2008-01-01
Residual stresses in a structure are generated as a result of the various fabrication and welding processes used to make the component. Being able to quantify these residual stresses is a key step in determining the continuing integrity of a structure in service. In this work, the residual stresses around a high strength, quenched and tempered steel T-butt web to curved plate weld have been measured using neutron strain scanning. The results show that the residual stresses near the weld were dominated by the welding residual stresses, while the stresses further from the weld were dominated by the bending residual stresses. The results suggest that the combination of welding-induced residual stress and significant pre-welding residual stress, as in the case of a thick bent section of plate can significantly alter the residual stress profile from that in a flat plate
de Bruin, Esther I; Formsma, Anne R; Frijstein, Gerard; Bögels, Susan M
2017-01-01
Work-related stress and associated illness and burnout is rising in western society, with now as much as almost a quarter of European and half of USA's employees estimated to be at the point of burnout. Mindfulness meditation, yoga, and physical exercise have all shown beneficial effects for work-related stress and illness. This proof of concept study assessed the feasibility, acceptability, and preliminary effects of the newly developed Mindful2Work training, a combination of physical exercise, restorative yoga, and mindfulness meditations, delivered in six weekly group sessions plus a follow-up session. Participants ( n = 26, four males), referred by company doctors with (work-related) stress and burnout complaints, completed measurements pre and post the intervention, as well as at 6-week (FU1) and 6-month (FU2) follow-up. Results showed very high feasibility and acceptability of the Mindful2Work training. The training and trainers were rated with an 8.1 and 8.4 on a 1-10 scale, respectively, and training dropout rate was zero. Significant improvements with (very) large effect sizes were demonstrated for the primary outcome measures of physical and mental workability, and for anxiety, depression, stress, sleep quality, positive and negative affect, which remained (very) large and mostly increased further over time. Risk for long-term dropout from work (checklist individual strength [CIS]) was 92 % at pre-test, reduced to 67 % at post-test, to 44 % at FU1, and 35 % at FU2, whereas employees worked (RTWI) 65 % of their contract hours per week at pre-test, which increased to 73 % at post-test, 81 % at FU1 and 93 % at FU2. Intensity of home practice or number of attended sessions were not related to training effects. To conclude, the newly developed Mindful2Work training seems very feasible, and acceptable, and although no control group was included, the large effects of Mindful2Work are highly promising.
Effects of drought stress on seed sink strength and leaf protein ...
African Journals Online (AJOL)
Assimilate availability and the capacity to utilise them in the reproductive structures to a large extent determine reproductive sink establishment and yield of crops under drought stress. This study was carried out to investigate the effect of drought stress imposed at early pod-fill stage on seed sink strength of common bean ...
Directory of Open Access Journals (Sweden)
simin dokht kalani
2017-05-01
Full Text Available The aim of the study was to compare the protective and interpersonal strengths as positive personality traits in employees with healthy (G: good health pattern, S: sparing pattern and unhealthy (A: ambitious pattern, B: burnout pattern job stress coping styles. Therefore, 146 employees of an industrial organization in Mashhad were selected by stratified random sampling and asked to respond to research tools. The instruments were the Values in Action Inventory of Strengths from Peterson & Seligman and Work-related Behavior and Experience Patterns Questionnaire from Schaarschmidt & Fischer. The results of multivariate analysis of variance showed that employees with healthy coping styles had higher means of protective and interpersonal strengths than unhealthy subjects. These findings open a new field for research on the role of personality in coping with work-related stress. Character strengths are trainable personal characteristics. Therefore, they are valuable resources to improve coping with work-related stress and to decreasing its negative effects.
Growth of marine yeast on different strength of stress solutes
Digital Repository Service at National Institute of Oceanography (India)
Gupta, R.
tested against the stress solutes NaCl (0-16%), potassium chloride (KCl) and sodium sulphate (Na sub(2) SO sub(4)) at 0.4%, 4% and 8% concentrations. D. hansenii and D. marama were the most versatile isolates exhibiting excellent growth in all...
Stress corrosion cracking of several high strength ferrous and nickel alloys
Nelson, E. E.
1971-01-01
The stress corrosion cracking resistance of several high strength ferrous and nickel base alloys has been determined in a sodium chloride solution. Results indicate that under these test conditions Multiphase MP35N, Unitemp L605, Inconel 718, Carpenter 20Cb and 20Cb-3 are highly resistant to stress corrosion cracking. AISI 410 and 431 stainless steels, 18 Ni maraging steel (250 grade) and AISI 4130 steel are susceptible to stress corrosion cracking under some conditions.
Popp, Kristin L; McDermott, William; Hughes, Julie M; Baxter, Stephanie A; Stovitz, Steven D; Petit, Moira A
2017-01-01
To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture. We recruited 32 competitive distance runners aged 18-35, with (SFX, n=16) or without (NSFX, n=16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm 3 ), total (ToA) and cortical (CtA) bone areas (mm 2 ), and estimated compressive bone strength (bone strength index; BSI, mg/mm 4 ) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm 3 and strength strain index; SSIp, mm 3 ) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm 2 /N∗kg -1 ) at all cortical sites. SSIp and Zp were 9-11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11-17% lower bone strength relative to mean pkZ GRFs (phistory of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture. Copyright Â© 2016. Published by Elsevier Inc.
Fault roughness and strength heterogeneity control earthquake size and stress drop
Zielke, Olaf
2017-01-13
An earthquake\\'s stress drop is related to the frictional breakdown during sliding and constitutes a fundamental quantity of the rupture process. High-speed laboratory friction experiments that emulate the rupture process imply stress drop values that greatly exceed those commonly reported for natural earthquakes. We hypothesize that this stress drop discrepancy is due to fault-surface roughness and strength heterogeneity: an earthquake\\'s moment release and its recurrence probability depend not only on stress drop and rupture dimension but also on the geometric roughness of the ruptured fault and the location of failing strength asperities along it. Using large-scale numerical simulations for earthquake ruptures under varying roughness and strength conditions, we verify our hypothesis, showing that smoother faults may generate larger earthquakes than rougher faults under identical tectonic loading conditions. We further discuss the potential impact of fault roughness on earthquake recurrence probability. This finding provides important information, also for seismic hazard analysis.
International Nuclear Information System (INIS)
Onuma, Hiroshi; Aoyagi, Yukio
1976-01-01
The purpose of this investigation was to study the ultimate strength failure mode and deformation behavior of concrete under short-term biaxial compressive stresses, as an aid to design and analyze the concrete structures subjected to multiaxial compression such as prestressed or reinforced concrete vessel structures. The experimental work on biaxial compression was carried out on the specimens of three mix proportions and different ages with 10cm x 10cm x 10cm cubic shape in a room controlled at 20 0 C. The results are summarized as follows. (1) To minimize the surface friction between specimens and loading platens, the pads of teflon sheets coated with silicone grease were used. The coefficient of friction was measured and was 3 percent on the average. (2) The test data showed that the strength of the concrete subjected to biaxial compression increased as compared to uniaxial compressive strength, and that the biaxial strength increase was mainly dependent on the ratio of principal stresses, and it was hardly affected by mix proportions and ages. (3) The maximum increase of strength, which occurred at the stress ratio of approximately sigma 2 /sigma 1 = 0.6, was about 27 percent higher than the uniaxial strength of concrete. (4) The ultimate strength in case of biaxial compression could be approximated by the parabolic equation. (Kako, I.)
Strength and deformability of graphite under cyclic stresses and temperatures
International Nuclear Information System (INIS)
Umanskij, Eh.S.; Uskov, E.I.; Bogomolov, A.V.; Aleksyuk, M.M.
1978-01-01
Presented are the results of investigations into a durability of two types of reactor graphites with the average density of 1.8 and 1.65 g/cm 2 under static and cyclic stresses (0.65-0.75 kg/mm 2 ) and temperatures (800 deg C, 250 reversible 800 deg C 250 reversible 1500 deg C). The considerable anisotropy is stated: the durability of the samples under study cut out parallel to the billet axis, is more than twice higher in comparison with that of samples cut out normal to it
Homogeneity of small-scale earthquake faulting, stress, and fault strength
Hardebeck, J.L.
2006-01-01
Small-scale faulting at seismogenic depths in the crust appears to be more homogeneous than previously thought. I study three new high-quality focal-mechanism datasets of small (M angular difference between their focal mechanisms. Closely spaced earthquakes (interhypocentral distance stress orientation and fault strength (coefficient of friction) are inferred to be homogeneous as well, to produce such similar earthquakes. Over larger length scales (???2-50 km), focal mechanisms become more diverse with increasing interhypocentral distance (differing on average by 40-70??). Mechanism variability on ???2- to 50 km length scales can be explained by ralatively small variations (???30%) in stress or fault strength. It is possible that most of this small apparent heterogeneity in stress of strength comes from measurement error in the focal mechanisms, as negligibble variation in stress or fault strength (<10%) is needed if each earthquake is assigned the optimally oriented focal mechanism within the 1-sigma confidence region. This local homogeneity in stress orientation and fault strength is encouraging, implying it may be possible to measure these parameters with enough precision to be useful in studying and modeling large earthquakes.
Effects of residual stress on fatigue strength of small diameter welded pipe joint
International Nuclear Information System (INIS)
Yamashita, Tetsuo; Hattori, Takahiro; Nomoto, Toshiharu; Iida, Kunihiro; Sato, Masanobu
1996-01-01
A power plant consists of many welded components, therefore, it is essential in establishing the reliability of the power plant to maintain the reliability of all welded components. The fatigue failure caused by mechanical vibrations of small diameter welded joints, which is represented by socket welded joints, is one of the major causes of trouble for the welded parts of the power plant. Here, bending fatigue tests were conducted to investigate the fatigue strength of small diameter socket welded pipe joints. In the most cases of large diameter socket joints, a fatigue crack started from the root of the fillet weld though the stress amplitude at the root was smaller than that at the toe of fillet weld. Additionally, the fatigue strength was affected by the weld bead sequence. The residual stress was considered to be one of the important parameters governing fatigue strength, therefore, its effects were investigated. In several types of pipe joints, the local stress and residual stress distributions were calculated by finite element analysis. The residual stresses were compressive at the toe and tensile at the root of the socket welded joints. Based on these results, the effects of residual stresses on the fatigue strength are discussed for small diameter welded pipe joints in the present work
Effect of residual stresses on fatigue strength of plasma nitrided 4140 steel
International Nuclear Information System (INIS)
Aghazadeh, J.; Amidi, M.R.
2004-01-01
Almost every method that has been presented to determine residual stress has some limitation and complexities. The aim of this work is to present a new, yet simple method so called strain indentation for measuring the residual stresses particularly in thin layers. In this method in addition to the precision measurements, components of residual stress at different directions may be determined. AISI 4140 steel specimens nitrided at 350 d ig C , 450 d ig C and 550 d ig C for 5 hours in the mixture of 75% nitrogen- 25% hydrogen gas. The, components of residual stress in the radials axial and hoop directions in the nitrided layer were determined considering the elastic strain recovery after removal of residual stress inducer(i.e. the nitrided layer). Fatigue strength of the nitrided specimens was obtained by plotting the S-N curves and fractographic studies carried out on the fracture surface of the specimens. The effect of residual stress on the stress pattern was simulated. The calculated residual stress components were in the range of 40-210 Mpa and the radial components of residual stress were more than the other two directions. Maximum fatigue strength improvement of up to 110% was observed in the plasma nitrided specimens at 550 d ig C and also 40% improvement in fatigue strength was detected by increasing the nitriding temperature from 350 d ig C to 550 d ig C . This was due to 100% increase in residual stress. Fatigue crack growth velocity in the hoop direction was more than that of radial direction. This seems to be due to higher radial residual stress component compared with the hoop stress component in the sub layer
simin dokht kalani; Zahra Zahra; hamidreza oreyzi
2017-01-01
The aim of the study was to compare the protective and interpersonal strengths as positive personality traits in employees with healthy (G: good health pattern, S: sparing pattern) and unhealthy (A: ambitious pattern, B: burnout pattern) job stress coping styles. Therefore, 146 employees of an industrial organization in Mashhad were selected by stratified random sampling and asked to respond to research tools. The instruments were the Values in Action Inventory of Strengths from Peterson & Se...
Energy Technology Data Exchange (ETDEWEB)
Menig, R.; Schulze, V.; Voehringer, O. [Inst. fuer Werkstoffkunde I, Univ. of Karlsruhe (TH), Karlsruhe (Germany)
2002-07-01
Increases of residual stress stability and alternating bending strength of shot peened AISI 4140 are obtained by successive annealing treatments. This is caused by static strain aging effects, which lead to pinning of dislocations by carbon atoms and finest carbides. It will be shown that by short-time annealing of a quenched and tempered AISI 4140 it is possible to maximize the positive effect of static strain aging, while minimizing the detrimental effect of thermal residual stress relaxation, which was measured by X-ray diffraction method. Static strain aging effects were also found to be responsible for an increase of the quasi static and cyclic surface yield strengths. (orig.)
The theoretical shear strength of fcc crystals under superimposed triaxial stress
Energy Technology Data Exchange (ETDEWEB)
Cerny, M., E-mail: cerny.m@fme.vutbr.cz [Institute of Engineering Physics, Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2, CZ-616 69 Brno (Czech Republic); Pokluda, J. [Institute of Engineering Physics, Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2, CZ-616 69 Brno (Czech Republic)
2010-05-15
The influence of a triaxial stress applied normally to shear planes and shear direction during affine shear deformation of face-centered cubic crystals on the theoretical shear strength is studied for the <112-bar >{l_brace}111{r_brace} shear system using first-principles methods. The applied relaxation procedure guarantees that the modeled system is subjected to a superposition of shear, normal and in-plane stresses with individually adjustable in-plane and normal stress values. The theoretical shear strengths of individual elements prove to be qualitatively different functions of the superimposed stresses. In the special case of hydrostatic loading, however, these functions are qualitatively uniform. This behavior is discussed in terms of the electronic structure.
Effect of nonlinear stress-strain relationship on bending strength of isotropic graphite
International Nuclear Information System (INIS)
Arai, Taketoshi; Oku, Tatsuo
1978-05-01
Four-point bending tests were made on rectangular isotropic 7477PT graphite specimens of different sizes to observe the relation between load and outermost fiber strain. Analytical methods, allowing for nonlinear stress-strain relationships different between tension and compression, were developed for calculating the fiber stress distribution in a beam and the failure probability based on the Weibull statistical theory for bending fracture. With increase of the stress, the stress-strain curves for tension deviate from the linearity and also from those for compression. The true bending strengths of the rectangular bars are 10 -- 20 percent lower than elastic bending strengths. Revised Weibull theory gives failure probability distributions agreeing with measured ones, compared with the theory based on elastic behavior. (auth.)
Combinatorial Proofs and Algebraic Proofs
Indian Academy of Sciences (India)
Permanent link: https://www.ias.ac.in/article/fulltext/reso/018/07/0630-0645. Keywords. Combinatorial proof; algebraic proof; binomial identity; recurrence relation; composition; Fibonacci number; Fibonacci identity; Pascal triangle. Author Affiliations. Shailesh A Shirali1. Sahyadri School Tiwai Hill, Rajgurunagar Pune 410 ...
Goh, Yun Lin Daphne; Wilkinson, Ross B.
2017-01-01
Interpersonal relationships are the recent focus of research identifying protective factors in adolescent psychological health. Using an attachment theory perspective, this study examines the relationship of normative attachment strength and individual differences in attachment expectancies on self-reports of depression and stress in 511…
International Nuclear Information System (INIS)
Edstrom, C.M.; Blakeslee, J.J.
1980-01-01
5083 aluminium with 25% cold work must be processed above 215 0 C or below 70 0 C to avoid forming continuous precipitate in the grain boundaries which makes the material susceptible to stress corrosion cracking. Time at temperature above 215 0 C should be held to minimum (less than 30 min) to retain some strength from the 25% cold work
Nakwattanaset, Aeksuwat; Suranuntchai, Surasak
2018-03-01
Normally, Forming Limit Curves (FLCs) can’t explain for shear fracture better than Damage Curve, this article aims to show the experimental of Forming Limit Curve (FLC) for Advanced High Strength Steel (AHSS) sheets grade JAC780Y with the Nakazima forming test and tensile tests of different sample geometries. From these results, the Forming Limit Curve (strain space) was transformed to damage curve (stress space) between plastic strain and stress triaxiality. Therefore, Stress space transformed using by Hill-48 and von-Mises yield function. This article shows that two of these yield criterions can use in the transformation.
Residual stresses and strength of multilayer tape cast solid oxide fuel and electrolysis half-cells
DEFF Research Database (Denmark)
Charlas, Benoit; Frandsen, Henrik Lund; Brodersen, Karen
2015-01-01
those with 3 layers (MTC3: without barrier layer). The bending strength of MTC3 and MTC4 under various loading orientations (electrolyte on the tensile or compressive side of the loading) is compared. The analysis, by taking residual stresses into account, shows that the strength of the half...... coefficient (TEC) mismatch between the layers, cumulated from high temperature, induces significant residual stresses in the half-cells. Furthermore, it has been observed that MTC half-cells with 4 layers (MTC4: support, fuel electrode, electrolyte and barrier layer) are sometimes more fragile to handle than...... stresses, especially in the outer barrier-layer, possible changes to the layer properties are discussed and some optimization guidelines proposed....
Directory of Open Access Journals (Sweden)
Watson Julian Matthew
2015-03-01
Full Text Available Although rock strength anisotropy is a well-known phenomenon in rock mechanics, its impact on geotechnical design is often ignored or underestimated. This paper explores the concept of anisotropy in a high stress environment using an improved unified constitutive model (IUCM, which can account for more complex failure mechanisms. The IUCM is used to better understand the typical responses of anisotropic rocks to underground mining. This study applies the IUCM to a proposed rock shaft located in high stress/anisotropic conditions. Results suggest that the effect of rock strength anisotropy must be taken into consideration when assessing the rock mass response to mining in high stress and anisotropic rock conditions.
Stress orientations in subduction zones and the strength of subduction megathrust faults.
Hardebeck, Jeanne L
2015-09-11
Subduction zone megathrust faults produce most of the world's largest earthquakes. Although the physical properties of these faults are difficult to observe directly, their frictional strength can be estimated indirectly by constraining the orientations of the stresses that act on them. A global investigation of stress orientations in subduction zones finds that the maximum compressive stress axis plunges systematically trenchward, consistently making an angle of 45° to 60° with respect to the subduction megathrust fault. These angles indicate that the megathrust fault is not substantially weaker than its surroundings. Together with several other lines of evidence, this implies that subduction zone megathrusts are weak faults in a low-stress environment. The deforming outer accretionary wedge may decouple the stress state along the megathrust from the constraints of the free surface. Copyright © 2015, American Association for the Advancement of Science.
Fractographic investigation of stress corrosion cracking of steels for high-strength bolts
International Nuclear Information System (INIS)
Gladshtejn, L.I.; Goritskij, V.M.; Evtushenko, N.A.; Sokolov, S.P.; Panfilova, L.M.
1980-01-01
By the methods of quantitative fractography studied is the effect of chemical composition on stress corrosion cracking resistance in the mean agressive medium (pH=2.2) and the fracture structure of cylindrical delta samples with the notch (K=2.75) of high-strength chromium steel. It is shown that the alloying of the 40 steel with Cr, Si, V increases its strength under short-time loading but leads to forming of brittle areas in fracture under long time effect of corrosion medium
Joshi, Mark
2015-01-01
This innovative textbook introduces a new pattern-based approach to learning proof methods in the mathematical sciences. Readers will discover techniques that will enable them to learn new proofs across different areas of pure mathematics with ease. The patterns in proofs from diverse fields such as algebra, analysis, topology and number theory are explored. Specific topics examined include game theory, combinatorics, and Euclidean geometry, enabling a broad familiarity. The author, an experienced lecturer and researcher renowned for his innovative view and intuitive style, illuminates a wide range of techniques and examples from duplicating the cube to triangulating polygons to the infinitude of primes to the fundamental theorem of algebra. Intended as a companion for undergraduate students, this text is an essential addition to every aspiring mathematician’s toolkit.
Safety enhancement of composites via periodic proof testing
Woodward, Joseph H.
1993-01-01
Approved for public release; distribution is unlimited. The development of new composite materials, which lack the historical field data base, has led to the need for an accelerated life testing method applicable to composites. Accelerated life testing by increasing the sustained stress levels requires the modeling and validation of a strength-life relation. Proof testing of composite fibers by over-loading is one step in the understanding of the relationship. It is also important in the r...
International Nuclear Information System (INIS)
Barsoum, Z.; Khurshid, M.; Barsoum, I.
2012-01-01
Highlights: ► Fatigue testing and evaluation of friction stir welded butt and overlap joints. ► Evaluation based on nominal and effective notch stress concept. ► Comparison with different design recommendations and codes. ► Higher fatigue strength and SN-slopes is observed. ► New fatigue design recommendations proposed for FSW joints. -- Abstract: In this study the fatigue strength is investigated for Friction Stir Welded (FSW) overlap and butt welded joints in different thicknesses based on nominal and effective notch stress concepts. The fatigue test results are compared with fatigue strength recommendations according to EN 1999-1-3 and International Institute of Welding (IIW). The results are also compared with available published data and Finite Element Analysis (FEA) is carried out to investigate the effect of plate thickness and nugget size on the fatigue strength of overlap joints. 3–3 mm butt welded joints shows the highest fatigue strength in comparison with 3–5 mm butt welded and overlap joints. Slopes of the SN-curves for two different joint types differ from the slope recommended by IIW. A specific failure trend is observed in overlap FSW joints. However, the slopes of the SN-curves are in close agreement with slopes found in EN 1999-1-3. The slopes of various published results and test results presented in this study are in good agreement with each other. The suggested fatigue design curves for the nominal and effective notch stress concept have a higher slope than given for fusion welds by IIW.
Stress-strain relationship of high-strength steel (HSS) reinforcing bars
Anggraini, Retno; Tavio, Raka, I. Gede Putu; Agustiar
2018-05-01
The introduction of High-Strength Steel (HSS) reinforcing bars in reinforced concrete members has gained much attention in recent years and led to many advantages such as construction timesaving. It is also more economical since it can reduce the amount of reinforcing steel bars used in concrete members which in turn alleviates the congestion of reinforcement. Up to present, the building codes, e.g. American Concrete Institute (ACI) 318M-14 and Standard National Indonesia (SNI) 2847:2013, still restrict the use of higher-strength steel reinforcing bars for concrete design up to Grade 420 MPa due to the possible suspected brittle behavior of concrete members. This paper evaluates the characteristics of stress-strain relationships of HSS bars if they are comparable to the characteristics of those of Grade 420 MPa. To achieve the objective of the study, a series of steel bars from various grades (420, 550, 650, and 700 MPa) was selected. Tensile tests of these steel samples were conducted under displacement-controlled mode to capture the complete stress-strain curves and particularly the post-yield response of the steel bars. The results indicate that all the steel bars tested had the actual yield strengths greater than the corresponding specified values. The stress-strain curves of HSS reinforcing bars (Grade 550, 650, and 700 MPa) performed slightly different characteristics with those of Grade 420 MPa.
Linares, Leanne A.; Smith, Phil R.
2009-01-01
A geometry textbook or mathematics journal that prints all the work that mathematicians use as they generate proofs of mathematical results would be rare indeed. The false starts, the tentative conjectures, and the arguments that led nowhere--these are conveniently omitted; only the final successful product is presented to the world. To students…
Czech Academy of Sciences Publication Activity Database
Krajíček, Jan
2004-01-01
Roč. 69, č. 2 (2004), s. 387-397 ISSN 0022-4812 R&D Projects: GA AV ČR IAA1019901; GA MŠk LN00A056 Institutional research plan: CEZ:AV0Z1019905 Keywords : propositional proof system s * circuits * polynomial simulation Subject RIV: BA - General Mathematics Impact factor: 0.331, year: 2004
Implementation of a Stress-dependent Strength Material Model in PLAXIS 3D
DEFF Research Database (Denmark)
Knudsen, Bjørn S.; Østergaard, Martin Underlin; Clausen, Johan
To perform tests on bucket foundations, full-scale testing is rarely used since it is rather expensive. Instead small-scale testing is done to examine the static and dynamic behaviour of such structures. In the laboratory at Aalborg University, small-scale testing of offshore support structures can...... be performed in a pressure tank, where a pressure can be applied in order to simulate deep water situations. Since the test set-up is downscaled 15 to 30 times compared to real-life structures, stresses and strains will be downscaled too. For soils, normally a Mohr-Coulomb failure criterion is used......, and in the region of small stresses, a non-linear behaviour is observed - unlike the linear behaviour normally assumed in Mohr-Coulomb. To better model this non-linearity, a stress-dependent model for the strength of the soil material is sought to be implemented in PLAXIS 3D through FORTRAN to improve...
Li, Xiao; Ye, Jiansong; Zhang, Hangcheng; Feng, Tao; Chen, Jianqing; Hu, Xiaojun
2017-08-01
We firstly used sandblasting to treat austenite stainless steel and then deposited a Cr/CrN interlayer by close field unbalanced magnetron sputtering on it. After that, diamond films were prepared on the interlayer. It is found that the sandblasting process induces phase transition from austenite to martensite in the surface region of the stainless steel, which decreases thermal stress in diamond films due to lower thermal expansion coefficient of martensite phase compared with that of austenite phase. The sandblasting also makes stainless steel's surface rough and the Cr/CrN interlayer film inherits the rough surface. This decreases the carburization extent of the interlayer, increases nucleation density and modifies the stress distribution. Due to lower residual stress and small extent of the interlayer's carburization, the diamond film on sandblast treated austenite stainless steel shows enhanced adhesion strength.
Andrews, Clare; Nettle, Daniel; Larriva, Maria; Gillespie, Robert; Reichert, Sophie; Brilot, Ben O; Bedford, Thomas; Monaghan, Pat; Spencer, Karen A; Bateson, Melissa
2017-09-01
The acute stress response functions to prioritize behavioural and physiological processes that maximize survival in the face of immediate threat. There is variation between individuals in the strength of the adult stress response that is of interest in both evolutionary biology and medicine. Age is an established source of this variation-stress responsiveness diminishes with increasing age in a range of species-but unexplained variation remains. Since individuals of the same chronological age may differ markedly in their pace of biological ageing, we asked whether biological age-measured here via erythrocyte telomere length-predicts variation in stress responsiveness in adult animals of the same chronological age. We studied two cohorts of European starlings in which we had previously manipulated the rate of biological ageing by experimentally altering the competition experienced by chicks in the fortnight following hatching. We predicted that individuals with greater developmental telomere attrition, and hence greater biological age, would show an attenuated corticosterone (CORT) response to an acute stressor when tested as adults. In both cohorts, we found that birds with greater developmental telomere attrition had lower peak CORT levels and a more negative change in CORT levels between 15 and 30 min following stress exposure. Our results, therefore, provide strong evidence that a measure of biological age explains individual variation in stress responsiveness: birds that were biologically older were less stress responsive. Our results provide a novel explanation for the phenomenon of developmental programming of the stress response: observed changes in stress physiology as a result of exposure to early-life adversity may reflect changes in ageing.
Liu, Junfeng; Yang, Haiqing; Xiao, Yang; Zhou, Xiaoping
2018-05-01
The fracture characters are important index to study the strength and deformation behavior of rock mass in rock engineering. In order to investigate the influencing mechanism of loading conditions on the strength and macro-mesoscopic fracture character of rock material, pre-cracked granite specimens are prepared to conduct a series of uniaxial compression experiments. For parts of the experiments, stress relaxation tests of different durations are also conducted during the uniaxial loading process. Furthermore, the stereomicroscope is adopted to observe the microstructure of the crack surfaces of the specimens. The experimental results indicate that the crack surfaces show several typical fracture characters in accordance with loading conditions. In detail, some cleavage fracture can be observed under conventional uniaxial compression and the fractured surface is relatively rough, whereas as stress relaxation tests are attached, relative slip trace appears between the crack faces and some shear fracture starts to come into being. Besides, the crack faces tend to become smoother and typical terrace structures can be observed in local areas. Combining the macroscopic failure pattern of the specimens, it can be deduced that the duration time for the stress relaxation test contributes to the improvement of the elastic-plastic strain range as well as the axial peak strength for the studied material. Moreover, the derived conclusion is also consistent with the experimental and analytical solution for the pre-peak stage of the rock material. The present work may provide some primary understanding about the strength character and fracture mechanism of hard rock under different engineering environments.
Hartmann, E C; Stickley, G W
1942-01-01
Fatigue-test were conducted on six specimens made from 3/4-inch-diameter 17S-T rolled-and-drawn rod for the purpose of obtaining additional data on the fatigue life of the material at stresses up to the static strength. The specimens were tested in direct tension using a stress range from zero to a maximum in tension. A static testing machine was used to apply repeated loads in the case of the first three specimens; the other three specimens were tested in a direct tension-compression fatigue machine. The direct-stress fatigue curve obtained for the material indicates that, in the range of stresses above about two-thirds the tensile strength, the fatigue strength is higher than might be expected by simply extrapolating the ordinary curve of stress plotted against the number of cycles determined at lower stresses.
Li, Xibing; Du, Kun; Li, Diyuan
2015-11-01
True triaxial tests have been carried out on granite, sandstone and cement mortar using cubic specimens with the process of unloading the minor principal stress. The strengths and failure modes of the three rock materials are studied in the processes of unloading σ 3 and loading σ 1 by the newly developed true triaxial test system under different σ 2, aiming to study the mechanical responses of the rock in underground excavation at depth. It shows that the rock strength increases with the raising of the intermediate principal stress σ 2 when σ 3 is unloaded to zero. The true triaxial strength criterion by the power-law relationship can be used to fit the testing data. The "best-fitting" material parameters A and n ( A > 1.4 and n plastic deformation. The maximum extension strain criterion Stacey (Int J Rock Mech Min Sci Geomech Abstr 651 18(6):469-474, 1981) can be used to explain the change of failure mode from shear to slabbing for strong and hard rocks under true triaxial unloading test condition.
International Nuclear Information System (INIS)
Hoche, Holger; Oechsner, Matthias
2017-01-01
Delayed brittle fractures of high-strength bolts of the strength class 10.9 are presented, taking the example of three damage cases. The respective damage mechanisms could be attributed to hydrogen induced stress corrosion which was caused, in turn, by hydrogen absorption during operation. The examples were chosen with a particular focus on the material condition's susceptibility which explains the cause for the occurrence of the damage mechanism. However, in only one of the three cases the susceptibility was evident and could be explained by violations of normative specifications and an unfavorable material choice. Whereas in the two other examples, only slight or no deviations from the standards and/or regulations could be found. The influencing parameters that caused the damage, those that further promoted the damage, as well as possible corrective actions are discussed taking into account the three exemplary damage cases.
Bayesian and Classical Estimation of Stress-Strength Reliability for Inverse Weibull Lifetime Models
Directory of Open Access Journals (Sweden)
Qixuan Bi
2017-06-01
Full Text Available In this paper, we consider the problem of estimating stress-strength reliability for inverse Weibull lifetime models having the same shape parameters but different scale parameters. We obtain the maximum likelihood estimator and its asymptotic distribution. Since the classical estimator doesn’t hold explicit forms, we propose an approximate maximum likelihood estimator. The asymptotic confidence interval and two bootstrap intervals are obtained. Using the Gibbs sampling technique, Bayesian estimator and the corresponding credible interval are obtained. The Metropolis-Hastings algorithm is used to generate random variates. Monte Carlo simulations are conducted to compare the proposed methods. Analysis of a real dataset is performed.
Chen, Bai-Qiao; Guedes Soares, C.
2018-03-01
The present work investigates the compressive axial ultimate strength of fillet-welded steel-plated ship structures subjected to uniaxial compression, in which the residual stresses in the welded plates are calculated by a thermo-elasto-plastic finite element analysis that is used to fit an idealized model of residual stress distribution. The numerical results of ultimate strength based on the simplified model of residual stress show good agreement with those of various methods including the International Association of Classification Societies (IACS) Common Structural Rules (CSR), leading to the conclusion that the simplified model can be effectively used to represent the distribution of residual stresses in steel-plated structures in a wide range of engineering applications. It is concluded that the widths of the tension zones in the welded plates have a quasi-linear behavior with respect to the plate slenderness. The effect of residual stress on the axial strength of the stiffened plate is analyzed and discussed.
Lifka, B. W.; Sprowls, D. O.; Kelsey, R. A.
1975-01-01
The variables studied in the stress-corrosion cracking performance of high strength aluminum alloys were: (1) corrosiveness of the environment, (2) specimen size and stiffness of the stressing system, (3) interpretation of transgranular cracking, and (4) interaction of the state of stress and specimen orientation in a product with an anisotropic grain structure. It was shown that the probability of failure and time to fracture for a specimen loaded in direct tension are influenced by corrosion pattern, the stressing assembly stiffness, and the notch tensile strength of the alloy. Results demonstrate that the combination of a normal tension stress and a shear stress acting on the plane of maximum susceptibility in a product with a highly directional grain cause the greatest tendency for stress-corrosion cracking.
Fatigue Behavior of Steel Fiber Reinforced High-Strength Concrete under Different Stress Levels
Zhang, Chong; Gao, Danying; Gu, Zhiqiang
2017-12-01
The investigation was conducted to study the fatigue behavior of steel fiber reinforced high-strength concrete (SFRHSC) beams. A series of 5 SFRHSC beams was conducted flexural fatigue tests at different stress level S of 0.5, 0.55, 0.6, 0.7 and 0.8 respectively. Static test was conducted to determine the ultimate static capacity prior to fatigue tests. Fatigue modes and S-N curves were analyzed. Besides, two fatige life prediction model were analyzed and compared. It was found that stress level S significantly influenced the fatigue life of SFRHSC beams and the fatigue behavior of SFRHSC beams was mainly determined by the tensile reinforcement.
Saeki, Junya; Nakamura, Masatoshi; Nakao, Sayaka; Fujita, Kosuke; Yanase, Ko; Morishita, Katsuyuki; Ichihashi, Noriaki
2017-01-01
A high proportion of flexor digitorum longus attachment is found at the posteromedial border of the tibia, which is the most common location of medial tibial stress syndrome (MTSS). Therefore, plantar flexion strength of the lesser toes could be related to MTSS; however, the relationship between MTSS and muscle strength of the hallux and lesser toes is not yet evaluated due to the lack of quantitative methods. This study investigated the muscle strength characteristics in runners with a history of MTSS by using a newly developed device to measure the muscle strength of the hallux, lesser toes, and ankle. This study comprised 27 collegiate male runner participants (20.0 ± 1.6 years, 172.1 ± 5.1 cm, 57.5 ± 4.0 kg). Maximal voluntary isometric contraction (MVIC) torque of the plantar flexion, dorsiflexion, inversion, and eversion of the ankle were measured by using an electric dynamometer. MVIC torque of the 1st metatarsophalangeal joint (MTPJ) and 2nd-5th MTPJ were measured by using a custom-made torque-measuring device. MVIC torques were compared between runners with and without a history of MTSS. MVIC torque of the 1st MTPJ plantar flexion was significantly higher in runners with a history of MTSS than in those without it. In contrast, there were no significant differences in the MVIC torque values of the 2nd-5th MTPJ plantar flexion and each MVIC torque of the ankle between runners with and without a history of MTSS. A history of MTSS increased the isometric FHL strength.
Micoulaud-Franchi, Jean-Arthur; Kotwas, Iliana; Lanteaume, Laura; Berthet, Christelle; Bastien, Mireille; Vion-Dury, Jean; McGonigal, Aileen; Bartolomei, Fabrice
2014-12-01
The present proof-of-concept study investigated the feasibility of skin conductance biofeedback training in reducing seizures in adults with drug-resistant temporal lobe epilepsy (TLE), whose seizures are triggered by stress. Skin conductance biofeedback aims to increase levels of peripheral sympathetic arousal in order to reduce cortical excitability. This might seem somewhat counterintuitive, since such autonomic arousal may also be associated with increased stress and anxiety. Thus, this sought to verify that patients with TLE and stress-triggered seizures are not worsened in terms of stress, anxiety, and negative emotional response to this nonpharmacological treatment. Eleven patients with drug-resistant TLE with seizures triggered by stress were treated with 12 sessions of biofeedback. Patients did not worsen on cognitive evaluation of attentional biases towards negative emotional stimuli (P>.05) or on psychometric evaluation with state anxiety inventory (P = .059); in addition, a significant improvement was found in the Negative Affect Schedule (P = .014) and in the Beck Depression Inventory (P = .009). Biofeedback training significantly reduced seizure frequency with a mean reduction of -48.61% (SD = 27.79) (P = .005). There was a correlation between the mean change in skin conductance activity over the biofeedback treatment and the reduction of seizure frequency (r(11) = .62, P = .042). Thus, the skin conductance biofeedback used in the present study, which teaches patients to achieve an increased level of peripheral sympathetic arousal, was a well-tolerated nonpharmacological treatment. Further, well-controlled studies are needed to confirm the therapeutic value of this nonpharmacological treatment in reducing seizures in adults with drug-resistant TLE with seizures triggered by stress. Copyright © 2014 Elsevier Inc. All rights reserved.
Davis, A Gabriell; Leary, Christopher J
2015-03-01
Mate selection can be stressful; time spent searching for mates can increase predation risk and/or decrease food consumption, resulting in elevated stress hormone levels. Both high predation risk and low food availability are often associated with increased variation in mate choice by females, but it is not clear whether stress hormone levels contribute to such variation in female behavior. We examined how the stress hormone corticosterone (CORT) affects female preferences for acoustic signals in the green treefrog, Hyla cinerea. Specifically, we assessed whether CORT administration affects female preferences for call rate - an acoustic feature that is typically under directional selection via mate choice by females in most anurans and other species that communicate using acoustic signals. Using a dual speaker playback paradigm, we show that females that were administered higher doses of CORT were less likely to choose male advertisement calls broadcast at high rates. Neither CORT dose nor level was related to the latency of female phonotactic responses, suggesting that elevated CORT does not influence the motivation to mate. Results were also not related to circulating sex steroids (i.e., progesterone, androgens or estradiol) that have traditionally been the focus of studies examining the hormonal basis for variation in female mate choice. Our results thus indicate that elevated CORT levels decrease the strength of female preferences for acoustic signals. Copyright © 2015 Elsevier Inc. All rights reserved.
Byrnes, Evan E; Vila Pouca, Catarina; Brown, Culum
2016-05-15
Cerebral lateralization is an evolutionarily deep-rooted trait, ubiquitous among the vertebrates and present even in some invertebrates. Despite the advantages of cerebral lateralization in enhancing cognition and facilitating greater social cohesion, large within population laterality variation exists in many animal species. It is proposed that this variation is maintained due links with inter-individual personality trait differences. Here we explored for lateralization in Port Jackson sharks (Heterodontus portusjacksoni) using T-maze turn and rotational swimming tasks. Additionally, we explored for a link between personality traits, boldness and stress reactivity, and cerebral lateralization. Sharks demonstrated large individual and sex biased laterality variation, with females demonstrating greater lateralization than males overall. Stress reactivity, but not boldness, was found to significantly correlate with lateralization strength. Stronger lateralized individuals were more reactive to stress. Demonstrating laterality in elasmobranchs for the first time indicates ancient evolutionary roots of vertebrate lateralization approximately 240 million years old. Greater lateralization in female elasmobranchs may be related enhancing females' ability to process multiple stimuli during mating, which could increase survivability and facilitate insemination. Despite contrasting evidence in teleost fishes, the results of this study suggest that stress reactivity, and other personality traits, may be linked to variation in lateralization. Copyright © 2016 Elsevier B.V. All rights reserved.
Study of flow stress and spall strength of additively manufactured Ti-6-4 alloy
Cohen, Amitay; Paris, Vitaly; Yosef-Hai, Arnon; Gudinetsky, Eli; Tiferet, Eitan
2017-06-01
The use of additive manufacturing (AM) by Electron Beam Melting (EBM) or Selective Laser Melting (SLM) has extensively grown in the past few years. A major goal in AM is to manufacture materials with mechanical properties at least as good as traditionally manufactured materials. In this work we present results of planar impact tests and Split Hopkinson Pressure Bar tests (SHPB) on Ti-6-4 manufactured by EBM and SLM processes. Results of planar impact tests on SLM samples display slightly higher spall strength compared to EBM while the stress at Hugoniot elastic limit (HEL) is practically the same. Stress strain curves based on SHPB measurements at two different strain rates present similar plastic flow stresses for SLM and EBM processed Ti-6-4 alloy, while the flow stress is about 20% higher than reported for commercial reference material. The strain to failure of both materials shows considerable strain rate sensitivity. The results of post-mortem analysis of spall fracture will also be presented.
Investigation of Stress Concentration and Casing Strength Degradation Caused by Corrosion Pits
Directory of Open Access Journals (Sweden)
Wei Yan
2016-01-01
Full Text Available Downhole casing and tubing are subjected to corrosion in many cases because of the exposure to corrosive environment. A more serious problem is that pitting corrosion occurs in the casing inner surface. Meanwhile, downhole strings are subjected to various forms of mechanical loads, for example, internal pressure load, external collapse load, or both. These loads acting on the corrosion pits will cause stress concentration and degrade the casing strength. Thus, it is essential to evaluate the stress concentration degree reasonably. The SCF (stress concentration factor is usually used to characterize the degree of stress concentration induced by corrosion pits. This paper presented a comparison on the SCFs regarding the analytical method for a single pit and experimental method for double pits. The results show that the SCF of a single pit depends mainly on the depth of the corrosion pit; however, the SCF of the double pits strongly depends on the pits distance. A correction factor of 1.3 was recommended in the double pits SCF prediction model.
MOMCILO STEVANOVIC; MILAN GORDIC; DANIELA SEKULIC; ISIDOR DJORDJEVIC
2006-01-01
The effect of edge interlaminar stresses on strength of carbon/epoxy laminates of different stacking geometry: cross-ply, quasi-isotropic and angle-ply laminates with additional 0º and 90º ply was studied. Coupons with two widths of laminates with an inverse stacking sequence were tested in static tensile tests. The effect of edge interlaminar stresses on strength was studied, by comparing the values of the tensile strength of laminate coupons of the same width with an inverse stacking sequen...
Mercuri, Marco; Scuderi, Marco Maria; Tesei, Telemaco; Carminati, Eugenio; Collettini, Cristiano
2018-04-01
A great number of earthquakes occur within thick carbonate sequences in the shallow crust. At the same time, carbonate fault rocks exhumed from a depth plasticity). We performed friction experiments on water-saturated simulated carbonate-bearing faults for a wide range of normal stresses (from 5 to 120 MPa) and slip velocities (from 0.3 to 100 μm/s). At high normal stresses (σn > 20 MPa) fault gouges undergo strain-weakening, that is more pronounced at slow slip velocities, and causes a significant reduction of frictional strength, from μ = 0.7 to μ = 0.47. Microstructural analysis show that fault gouge weakening is driven by deformation accommodated by cataclasis and pressure-insensitive deformation processes (pressure solution and granular plasticity) that become more efficient at slow slip velocity. The reduction in frictional strength caused by strain weakening behaviour promoted by the activation of pressure-insensitive deformation might play a significant role in carbonate-bearing faults mechanics.
Lithospheric Strength and Stress State: Persistent Challenges and New Directions in Geodynamics
Hirth, G.
2017-12-01
The strength of the lithosphere controls a broad array of geodynamic processes ranging from earthquakes, the formation and evolution of plate boundaries and the thermal evolution of the planet. A combination of laboratory, geologic and geophysical observations provides several independent constraints on the rheological properties of the lithosphere. However, several persistent challenges remain in the interpretation of these data. Problems related to extrapolation in both scale and time (rate) need to be addressed to apply laboratory data. Nonetheless, good agreement between extrapolation of flow laws and the interpretation of microstructures in viscously deformed lithospheric mantle rocks demonstrates a strong foundation to build on to explore the role of scale. Furthermore, agreement between the depth distribution of earthquakes and predictions based on extrapolation of high temperature friction relationships provides a basis to understand links between brittle deformation and stress state. In contrast, problems remain for rationalizing larger scale geodynamic processes with these same rheological constraints. For example, at face value the lab derived values for the activation energy for creep are too large to explain convective instabilities at the base of the lithosphere, but too low to explain the persistence of dangling slabs in the upper mantle. In this presentation, I will outline these problems (and successes) and provide thoughts on where new progress can be made to resolve remaining inconsistencies, including discussion of the role of the distribution of volatiles and alteration on the strength of the lithosphere, new data on the influence of pressure on friction and fracture strength, and links between the location of earthquakes, thermal structure, and stress state.
Earthquake-proof supporting structure in reactor vessel
International Nuclear Information System (INIS)
Sakurai, Akio; Sekine, Katsuhisa; Madokoro, Manabu; Katoono, Shin-ichi; Konno, Mutsuo; Suzuki, Takuro.
1990-01-01
Conventional earthquake-proof structure comprises a vessel vibration stopper integrated to a reactor vessel, powder for restricting the horizontal displacements, a safety vessel surrounds the outer periphery of the reactor vessel and a safety vessel vibration stopper integrated therewith, which are fixed to buildings. However, there was a problem that a great amount of stresses are generated in the base of the reactor vessel vibration stopper due to reaction of the powders which restrict thermal expansion. In order to remarkably reduce the reaction of the powers, powders are charged into a spaces formed between each of the reactor vessel vibration stopper, the safety vessel vibration stopper and the flexible member disposed between them. According to this constitution, the reactor vessel vibration stopper does not undergo a great reaction of the powers upon thermal expansion of the reactor vessel to moderate the generated stresses, maintain the strength and provide earthquake-proof supporting function. (N.H.)
Understanding mathematical proof
Taylor, John
2014-01-01
Introduction The need for proof The language of mathematics Reasoning Deductive reasoning and truth Example proofs Logic and ReasoningIntroduction Propositions, connectives, and truth tables Logical equivalence and logical implication Predicates and quantification Logical reasoning Sets and Functions Introduction Sets and membership Operations on setsThe Cartesian product Functions and composite functions Properties of functions The Structure of Mathematical ProofsIntroduction Some proofs dissected An informal framework for proofs Direct proof A more formal framework Finding Proofs Direct proo
International Nuclear Information System (INIS)
Kim, Jae Yong; Yoon, Kyung Ho; Kang, Heung Seok; Lee, Young Ho; Lee, Kang Hee; Kim, Hyung Kyu
2009-01-01
A fuel assembly is composed of 5 major components, such as a top end piece (TEP), a bottom end piece (BEP), spacer grids (SGs), guide tubes (GTs) and an instrumentation tube (IT) and fuel rods (FRs). There are no ASME criteria about all components except for a TEP/BEP. The TEP/BEP should satisfy stress intensity limits in case of condition A and B of ASME, Section III, Division 1 . Subsection NB. In a dual cooled fuel assembly, the array and position of fuels are changed from those of a conventional PWR fuel assembly to achieve a power uprating. The flow plates of top/bottom end pieces (TEP/BEP) have to be modified into proper shape to provide flow holes to direct the heated coolant into/out of the fuel assembly but structural intensity of these plates within a 22.241 kN axial loading should satisfy Tresca stress limits in ASME code. In this paper, stress linearization procedure and strength evaluation of a newly designed BEP for the dual cooled fuel assembly are described
Wang, Kaishi; Zhang, Fangzhou; Bordia, Rajendra K
2018-03-27
The ceramic-metal interface is present in various material structures and devices that are vulnerable to failures, like cracking, which are typically due to their incompatible properties, e.g., thermal expansion mismatch. In failure of these multilayer systems, interfacial shear strength is a good measure of the robustness of interfaces, especially for planar films. There is a widely-used shear lag model and method by Agrawal and Raj to analyse and measure the interfacial shear strength of thin brittle film on ductile substrates. The use of this classical model for a type of polymer derived ceramic coatings (thickness ~18 μm) on steel substrate leads to high values of interfacial shear strength. Here, we present finite element simulations for such a coating system when it is subjected to in-plane tension. Results show that the in-plane stresses in the coating are non-uniform, i.e., varying across the thickness of the film. Therefore, they do not meet one of the basic assumptions of the classical model: uniform in-plane stress. Furthermore, effects of three significant parameters, film thickness, crack spacing, and Young's modulus, on the in-plane stress distribution have also been investigated. 'Thickness-averaged In-plane Stress' (TIS), a new failure criterion, is proposed for estimating the interfacial shear strength, which leads to a more realistic estimation of the tensile strength and interfacial shear strength of thick brittle films/coatings on ductile substrates.
Yield strength, shear stress and toughness of YBCO samples textured by Bridgman technique
International Nuclear Information System (INIS)
Roa, J J; Capdevila, X G; Martinez, M; Segarra, M; Jimenez-Pique, E
2008-01-01
Mechanical properties of the orthorhombic phase of YBa 2 Cu 3 O 7-δ (Y-123) at room temperature have been investigated at different applied loads using nanoindentation technique. The study was carried out for several monodomains on the (001) planes for textured Bridgman samples with dispersed Y 2 BaCuO 5 (Y-211) particles as pinning centers. The yield strength (σ ys ), shear stress (τ m ) and toughness (K IC ) of Y123/Y211composite was determined at different applied loads. First and second mechanical properties have been calculated though the Hertz equations and the last one with Lawn et al. equations. Finally, the ultra-low imprints obtained by nanoindentation have been correlated with parameters obtained by Field Emission Scanning Electron Microscope (FE-SEM)
Energy Technology Data Exchange (ETDEWEB)
Ramirez, E. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas-UAEM, Av. Universidad 1001, 62209-Cuernavaca, Mor. (Mexico); Gonzalez-Rodriguez, J.G. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas-UAEM, Av. Universidad 1001, 62209-Cuernavaca, Mor. (Mexico)], E-mail: ggonzalez@uaem.mx; Torres-Islas, A.; Serna, S. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas-UAEM, Av. Universidad 1001, 62209-Cuernavaca, Mor. (Mexico); Campillo, B. [Intituto de Ciencias Fisicas-Facultad de Quimicas-Universidad Nacional Autonoma de Mexico Cuernavaca, Mor. (Mexico); Dominguez-Patino, G. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas-UAEM, Av. Universidad 1001, 62209-Cuernavaca, Mor. (Mexico); Juarez-Islas, J.A. [Instituto de Investigaciones en Materiales-Universidad Nacional Autonoma de Mexico, Circuito Exterior S/N, Cd. Universitaria, C.P. 04510, Mexico, D.F. (Mexico)
2008-12-15
The sulphide stress cracking (SSC) susceptibility of a newly developed high strength microalloyed steel with three different microstructures has been evaluated using the slow strain rate testing (SSRT) technique. Studies were complemented with potentiodynamic polarization curves and hydrogen permeation measurements. Material included a C-Mn steel having Ni, Cu, and Mo as main microalloying elements with three microstructures: martensitic, ferritic and ferritic + bainitic. Testing temperatures included 25, 50, 70 and 90 deg. C. Detailed SEM observations of the microstructure and fracture surfaces were done to identify possible degradation mechanisms. The results showed that in all cases, the corrosion rate, number of hydrogen atoms at the surface and the percentage reduction in area increased with temperature. The steel with a martensitic microstructure had the highest SSC susceptibility at all temperatures, whereas the ferritic steels were susceptible only at 25 deg. C, and the most likely mechanism is hydrogen embrittlement assisted by anodic dissolution.
International Nuclear Information System (INIS)
Kamaya, Masayuki
2016-01-01
In order to assess failure probability of cracked components, it is important to know the variations of the material properties and their influence on the failure load assessment. In this study, variations of the fracture toughness and stress-strain curve were investigated for cold worked stainless steel. The variations of the 0.2% proof and ultimate strengths obtained using 8 specimens of 20% cold worked stainless steel (CW20) were 77 MPa and 81 MPa, respectively. The respective variations were decreased to 13 and 21 MPa for 40% cold worked material (CW40). Namely, the variation in the tensile strength was decreased by hardening. The COVs (coefficients of variation) of fracture toughness were 7.3% and 16.7% for CW20 and CW40, respectively. Namely, the variation in the fracture toughness was increased by hardening. Then, in order to investigate the influence of the variations in the material properties on failure load of a cracked pipe, flaw assessments were performed for a cracked pipe subjected to a global bending load. Using the obtained material properties led to variation in the failure load. The variation in the failure load of the cracked pipe caused by the variation in the stress-strain curve was less than 1.5% for the COV. The variation in the failure load caused by fracture toughness variation was relatively large for CW40, although it was less than 2.0% for the maximum case. It was concluded that the hardening induced by cold working does not cause significant variation in the failure load of cracked stainless steel pipe. (author)
Lu, Yaqing; Hui, Hu; Gong, Jianguo
2018-05-01
Austenitic stainless steel is widely used in pressure vessels for the storage and transportation of liquid gases such as liquid nitrogen, liquid oxygen, and liquid hydrogen. Cryogenic pressure vessel manufacturing uses cold stretching technology, which relies heavily on welding joint performance, to construct lightweight and thin-walled vessels. Residual stress from welding is a primary factor in cases of austenitic stainless steel pressure vessel failure. In this paper, on the basis of Visual Environment 10.0 finite element simulation technology, the residual stress resulting from different welding strength matching coefficients (0.8, 1, 1.2, 1.4) for two S30408 plates welded with three-pass butt welds is calculated according to thermal elastoplastic theory. In addition, the stress field was calculated under a loading as high as 410 MPa and after the load was released. Path 1 was set to analyze stress along the welding line, and path 2 was set to analyze stress normal to the welding line. The welding strength matching coefficient strongly affected both the longitudinal residual stress (center of path 1) and the transverse residual stress (both ends of path 1) after the welding was completed. However, the coefficient had little effect on the longitudinal and transverse residual stress of path 2. Under the loading of 410 MPa, the longitudinal and transverse stress decreased and the stress distribution, with different welding strength matching coefficients, was less diverse. After the load was released, longitudinal and transverse stress distribution for both path 1 and path 2 decreased to a low level. Cold stretching could reduce the effect of residual stress to various degrees. Transverse strain along the stretching direction was also taken into consideration. The experimental results validated the reliability of the partial simulation.
Tests on creep and influence of creep on strength of concrete under multiaxial stresses
International Nuclear Information System (INIS)
Lanig, N.; Stoeckl, S.; Kupfer, H.
1988-12-01
Long-time tests of three-axially loaded, sealed cylindrical specimens d = 15 cm, h = 40 cm, were carried out. The 20-cm-cube strength of the concrete was app. 45 N/mm 2 . The creep stresses were chosen in the following ranges: 0,3 ≤ σ c /β c ≤ 2,1; 0 ≤ σ r /σ l ≤ 1,0. The creep coefficients obtained were clearly depending on the multi-axial stress conditions. The creep coefficients for a t = 2 years loading were reaching app. 1 for σ l /β c = 0,3 and app. 3 for σ l /β c = 2,1, when the test evaluation was based on the initial deformations meausred after 1 minute. For σ l /β c = 2,1 the creep coefficients obtained were about 4 times as large, proceeding form calculated elastic deformations. Further evaluations concerned the Young's modulus E, Poisson's ratio μ, the bulk modulus K and the shear modulus G. The preceding permanent load leads to an increase in the Young's modulus of the concrete in longitudinal direction of the specimen up to about 4 times the value of not preloaded comparative specimens. (orig.) [de
Reliability analysis of structures under periodic proof tests in service
Yang, J.-N.
1976-01-01
A reliability analysis of structures subjected to random service loads and periodic proof tests treats gust loads and maneuver loads as random processes. Crack initiation, crack propagation, and strength degradation are treated as the fatigue process. The time to fatigue crack initiation and ultimate strength are random variables. Residual strength decreases during crack propagation, so that failure rate increases with time. When a structure fails under periodic proof testing, a new structure is built and proof-tested. The probability of structural failure in service is derived from treatment of all the random variables, strength degradations, service loads, proof tests, and the renewal of failed structures. Some numerical examples are worked out.
Directory of Open Access Journals (Sweden)
Kaishi Wang
2018-03-01
Full Text Available The ceramic-metal interface is present in various material structures and devices that are vulnerable to failures, like cracking, which are typically due to their incompatible properties, e.g., thermal expansion mismatch. In failure of these multilayer systems, interfacial shear strength is a good measure of the robustness of interfaces, especially for planar films. There is a widely-used shear lag model and method by Agrawal and Raj to analyse and measure the interfacial shear strength of thin brittle film on ductile substrates. The use of this classical model for a type of polymer derived ceramic coatings (thickness ~18 μm on steel substrate leads to high values of interfacial shear strength. Here, we present finite element simulations for such a coating system when it is subjected to in-plane tension. Results show that the in-plane stresses in the coating are non-uniform, i.e., varying across the thickness of the film. Therefore, they do not meet one of the basic assumptions of the classical model: uniform in-plane stress. Furthermore, effects of three significant parameters, film thickness, crack spacing, and Young’s modulus, on the in-plane stress distribution have also been investigated. ‘Thickness-averaged In-plane Stress’ (TIS, a new failure criterion, is proposed for estimating the interfacial shear strength, which leads to a more realistic estimation of the tensile strength and interfacial shear strength of thick brittle films/coatings on ductile substrates.
Lätsch, Alexander
2018-04-01
More and more students report high level of perceived stress during childhood and adolescence, which is associated with socioemotional and behavioural strengths and difficulties. This study aims-based on the cognitive vulnerability-transactional stress theory-to examine perceived stress in early adolescence as a potential moderator in the association between depressive symptoms and socioemotional and behavioural strengths and difficulties from early to middle adolescence. Results of latent moderated structural equations with questionnaire data from a longitudinal study with 1,088 German students (Time 1: M age = 13.70, SD = 0.53; Time 2: N = 845, M age = 15.32, SD = 0.49) indicate that perceived stress functions as a moderator in the above-mentioned association and dominates the interaction if perceived strongly. Copyright © 2017 John Wiley & Sons, Ltd.
Mean Stress Effect on the Axial Fatigue Strength of DIN 34CrNiMo6 Quenched and Tempered Steel
Directory of Open Access Journals (Sweden)
Luis Pallarés-Santasmartas
2018-03-01
Full Text Available The present study consists of a theoretical and experimental investigation of the effect of axial mean stresses on the high cycle fatigue behaviour of DIN 34CrNiMo6 high strength steel in quenched and tempered conditions. The axial S-N curves under 4 different stresses ratios were obtained. Experimental results show that increasing the value of the tension mean stresses gradually reduces the axial stress amplitude the material can withstand without failure. Moreover, the compressive mean stresses show a beneficial effect in terms of the axial fatigue strength, resulting in a non-symmetrical Haigh diagram. A historic review of the axial mean stress effect is presented, showing the shape of the Haigh diagrams for ductile metals and presenting the most-known empirical and physical theories. The results for this steel are compared with the physical theories of Findley based on the critical plane; the Froustey’s and Marin’s methods, based on energetic theories; and the Crossland invariants method based on the Gough’s theory of fatigue damage. Taking into account the experimental results, a physical fatigue function based on energetic considerations is proposed. Its application to the fatigue case with mean stresses can be interpreted in terms of a balance of elastic energies of distortion and volume change. Macro-analyses of specimen fracture appearance were conducted in order to obtain the fracture characteristics for different mean stress values.
Directory of Open Access Journals (Sweden)
Amanda Maria de Oliveira Dal Piva
2018-01-01
Full Text Available This study evaluated the shear stress distribution on the adhesive interface and the bond strength between resin cement and two ceramics. For finite element analysis (FEA, a tridimensional model was made using computer-aided design software. This model consisted of a ceramic slice (10x10x2mm partially embedded on acrylic resin with a resin cement cylinder (Ø=3.4 mm and h=3mm cemented on the external surface. Results of maximum principal stress and maximum principal shear were obtained to evaluate the stress generated on the ceramic and the cylinder surfaces. In order to reproduce the in vitro test, similar samples to the computational model were manufactured according to ceramic material (Zirconia reinforced lithium silicate - ZLS and high translucency Zirconia - YZHT, (N=48, n=12. Half of the specimens were submitted to shear bond test after 24h using a universal testing machine (0.5 mm/min, 50kgf until fracture. The other half was stored (a (180 days, water, 37ºC prior to the test. Bond strength was calculated in MPa and submitted to analysis of variance. The results showed that ceramic material influenced bond strength mean values (p=0.002, while aging did not: YZHT (19.80±6.44a, YZHTa (17.95±7.21a, ZLS (11.88±5.40b, ZLSa (11.76±3.32b. FEA results showed tensile and shear stress on ceramic and cylinder surfaces with more intensity on their periphery. Although the stress distribution was similar for both conditions, YZHT showed higher bond strength values; however, both materials seemed to promote durable bond strength.
The stress-corrosion cracking behavior of high-strength aluminum powder metallurgy alloys
Pickens, J. R.; Christodoulou, L.
1987-01-01
The susceptibility to stress-corrosion cracking (SCC) of rapidly solidified (RS) aluminum powder metallurgy (P/M) alloys 7090 and 7091, mechanically alloyed aluminum P/M alloy IN* 9052, and ingot metallurgy (I/M) alloys of similar compositions was compared using bolt-loaded double cantilever beam specimens. In addition, the effects of aging, grain size, grain boundary segregation, pre-exposure embrittlement, and loading mode on the SCC of 7091 were independently assessed. Finally, the data generated were used to elucidate the mechanisms of SCC in the three P/M alloys. The IN 9052 had the lowest SCC susceptibility of all alloys tested in the peak-strength condition, although no SCC was observed in the two RS alloys in the overaged condition. The susceptibility of the RS alloys was greater in the underaged than the peak-aged temper. We detected no significant differences in susceptibility of 7091 with grain sizes varying from 2 to 300 μm. Most of the crack advance during SCC of 7091 was by hydrogen embrittlement (HE). Furthermore, both RS alloys were found to be susceptible to preexposure embrittlement—also indicative of HE. The P/M alloys were less susceptible to SCC than the I/M alloys in all but one test.
Chen, Hui; Cai, Li-Xun
2018-04-01
Based on the power-law stress-strain relation and equivalent energy principle, theoretical equations for converting between Brinell hardness (HB), Rockwell hardness (HR), and Vickers hardness (HV) were established. Combining the pre-existing relation between the tensile strength ( σ b ) and Hollomon parameters ( K, N), theoretical conversions between hardness (HB/HR/HV) and tensile strength ( σ b ) were obtained as well. In addition, to confirm the pre-existing σ b -( K, N) relation, a large number of uniaxial tensile tests were conducted in various ductile materials. Finally, to verify the theoretical conversions, plenty of statistical data listed in ASTM and ISO standards were adopted to test the robustness of the converting equations with various hardness and tensile strength. The results show that both hardness conversions and hardness-strength conversions calculated from the theoretical equations accord well with the standard data.
Energy Technology Data Exchange (ETDEWEB)
Menig, R.; Schulze, V.; Voehringer, O. [Inst. fuer Werkstoffkunde 1, Univ. Karlsruhe (TH), Karlsruhe (Germany)
2002-07-01
Increases of residual stress stability and alternating bending strength of shot peened AISI 4140 are obtained by successive annealing treatments. This is caused by static strain aging effects, which lead to pinning of dislocations by carbon atoms and very small carbides. It will be shown that by well directed annealing of a quenched and tempered AISI 4140 it is possible to maximize the positive effects of static strain aging, without causing extended thermal residual stress relaxation. The amount of yield stress increases caused by static strain aging is quantified using tensile tests. Static strain aging is also found to be responsible for an increase of the quasi static and cyclic surface yield strength present after shot peening. (orig.)
International Nuclear Information System (INIS)
Raghavender Rao, G.; Gupta, O.P.; Pradhan, B.
2011-01-01
Uniaxial isothermal stress relaxation tests (SRT) were performed on a tungsten-alloyed 10% Cr cast steel (G-X12Cr Mo W V Nb N 10 1 1) at temperatures of 580, 600 and 620 o C and initial strain levels of 0.2, 0.5 and 0.8%. Inelastic strain rates for different stresses were estimated from the stress versus time data generated from the tests. Conventional creep tests were also conducted on the same material at 580, 600 and 620 o C and at different stress levels. The strain rate data estimated from SRT were compared with minimum creep rates derived from the creep tests; the strain rates estimated from SRT with 0.8% initial strain level are in better agreement than those estimated from SRT with 0.2 and 0.5% initial strain levels. In order to ascertain the technique, stress relaxation behaviour was estimated from creep test data and compared with the stress relaxation curves obtained from SRT at corresponding temperatures. The stress relaxation curves obtained from SRT with 0.8% initial strain level are in good agreement with the stress relaxation curves estimated from the creep tests. It is concluded that the stress relaxation test with initial strain level of 0.8% could be considered as an appropriate short-term test technique for estimation of creep strength of newly developed materials.
National Research Council Canada - National Science Library
Underwood, John
2000-01-01
...; overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid...
Sullivan, Roy M.
2016-01-01
The stress rupture strength of silicon carbide fiber-reinforced silicon carbide composites with a boron nitride fiber coating decreases with time within the intermediate temperature range of 700 to 950 degree Celsius. Various theories have been proposed to explain the cause of the time-dependent stress rupture strength. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of silicon carbide fiber-reinforced silicon carbide composites. This is achieved through the development of a numerically based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time-marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time-dependent behavior.
Luttrell, K.M.; Tong, X.; Sandwell, D.T.; Brooks, B.A.; Bevis, M.G.
2011-01-01
The great 27 February 2010 Mw 8.8 earthquake off the coast of southern Chile ruptured a ???600 km length of subduction zone. In this paper, we make two independent estimates of shear stress in the crust in the region of the Chile earthquake. First, we use a coseismic slip model constrained by geodetic observations from interferometric synthetic aperture radar (InSAR) and GPS to derive a spatially variable estimate of the change in static shear stress along the ruptured fault. Second, we use a static force balance model to constrain the crustal shear stress required to simultaneously support observed fore-arc topography and the stress orientation indicated by the earthquake focal mechanism. This includes the derivation of a semianalytic solution for the stress field exerted by surface and Moho topography loading the crust. We find that the deviatoric stress exerted by topography is minimized in the limit when the crust is considered an incompressible elastic solid, with a Poisson ratio of 0.5, and is independent of Young's modulus. This places a strict lower bound on the critical stress state maintained by the crust supporting plastically deformed accretionary wedge topography. We estimate the coseismic shear stress change from the Maule event ranged from-6 MPa (stress increase) to 17 MPa (stress drop), with a maximum depth-averaged crustal shear-stress drop of 4 MPa. We separately estimate that the plate-driving forces acting in the region, regardless of their exact mechanism, must contribute at least 27 MPa trench-perpendicular compression and 15 MPa trench-parallel compression. This corresponds to a depth-averaged shear stress of at least 7 MPa. The comparable magnitude of these two independent shear stress estimates is consistent with the interpretation that the section of the megathrust fault ruptured in the Maule earthquake is weak, with the seismic cycle relieving much of the total sustained shear stress in the crust. Copyright 2011 by the American
Dooley, Larissa N; Slavich, George M; Moreno, Patricia I; Bower, Julienne E
2017-12-01
Stress research typically emphasizes the toxic effects of stress, but recent evidence has suggested that stress exposure, in moderation, can facilitate resilience. To test whether moderate stress exposure promotes psychological resilience to cancer, we examined the relationship between lifetime stress exposure prior to cancer diagnosis and postdiagnosis psychological functioning among 122 breast cancer survivors. Lifetime acute and chronic stress was assessed using an interview-based measure, and psychological functioning was assessed using measures of cancer-related intrusive thoughts and positive and negative affect. Results indicated that acute stress exposure was associated with cancer-related intrusive thoughts in a quadratic fashion (p = .016), such that participants with moderate acute stress reported fewer intrusive thoughts compared to those with low or high acute stress. Similarly, a quadratic relationship emerged between acute stress exposure and positive affect (p = .009), such that individuals with moderate acute stress reported the highest levels of positive affect. In contrast, acute and chronic stress were related to negative affect in a positive, linear fashion (ps < .05). In conclusion, moderate stress exposure was associated with indicators of psychological resilience among breast cancer survivors, supporting stress exposure as a key factor influencing adjustment to breast cancer and providing evidence for stress-induced resilience in a novel population. Copyright © 2017 John Wiley & Sons, Ltd.
Role of microstructure in the mean stress dependence of fatigue strength in Ti-6Al-4V alloy
Energy Technology Data Exchange (ETDEWEB)
Ivanova, S.G.; Cohen, F.S.; Biederman, R.R.; Sisson, R.D. Jr.
1999-07-01
The high cycle fatigue properties of Ti-6Al-4V alloy with six different microstructure/texture combinations were investigated. Only materials with lamellar and fine bimodal microstructures exhibited linear Goodman relationship on the constant fatigue life diagram. Materials with coarse bimodal and equiaxed microstructures had anomalous mean stress dependency, with HCF strength at intermediate mean stresses being significantly lower than predicted by Goodman relationship, regardless of whether material was forged or cross-rolled. The role of microstructure in mean stress sensitivity behavior of Ti-6Al-4V is studied. Cyclic strain tests were conducted for all microstructures, and the results of strain-controlled and stress-controlled cyclic tests are compared and discussed.
International Nuclear Information System (INIS)
Cheng Kui; Zhang, Sam; Weng Wenjian; Khor, Khiam Aik; Miao Shundong; Wang Yongsheng
2008-01-01
β-tricalcium phosphate (β-TCP) powders are embedded in a fluoridated hydroxyapatite (FHA) matrix to form β-TCP-FHA composites via colloidal-sol gel method. This composite layer is deposited on top of a FHA layer to form a β-TCP-FHA/FHA biphasic coating. The effect of the nanosized powder on the residual stress is characterized through the X-ray diffraction peak shift. The powder incorporation increases the residual stress, while a large amount of β-TCP (Ca powder /Ca sol ratio is higher than 1/2) results in less gel shrinkage that partially compensates the mismatch of thermal expansion coefficient and thus the residual stress. Despite the elevated residual stress as more powders are embedded, the coating adhesion strength remains virtually constant: around 430 mN-500 mN in scanning scratch test
Khattak, Abraiz; Amin, Muhammad; Iqbal, Muhammad; Abbas, Naveed
2018-02-01
Micro and nanocomposites of ethylene propylene diene monomer (EPDM) are recently studied for different characteristics. Study on life estimation and effects of multiple stresses on its dielectric strength and backbone scission and oxidation is also vital for endorsement of these composites for high voltage insulation and other outdoor applications. In order to achieve these goals, unfilled EPDM and its micro and nanocomposites are prepared at 23 phr micro silica and 6 phr nanosilica loadings respectively. Prepared samples are energized at 2.5 kV AC voltage and subjected for a long time to heat, ultraviolet radiation, acid rain, humidity and salt fog in accelerated manner in laboratory. Dielectric strength, leakage current and intensity of saturated backbone and carbonyl group are periodically measured. Loss in dielectric strength, increase in leakage current and backbone degradation and oxidation were observed in all samples. These effects were least in the case of EPDM nanocomposite. The nanocomposite sample also demonstrated longest shelf life.
Silva, G.; Rivolta, B.; Gerosa, R.; Derudi, U.
2013-01-01
For many years 7075 Aluminum alloys have been widely used especially in those applications for which highmechanical performances are required. It is well known that the alloy in the T6 condition is characterized bythe highest ultimate and yield strengths, but, at the same time, by poor stress corrosion cracking (SCC)resistance. For this reason, in the aeronautic applications, new heat treatments have been introduced toproduce T7X conditions, which are characterized by lower mechanical strengt...
Evaluation of strength-controlling defects in paper by stress concentration analyses
John M. Considine; David W. Vahey; James W. Evans; Kevin T. Turner; Robert E. Rowlands
2011-01-01
Cellulosic webs, such as paper materials, are composed of an interwoven, bonded network of cellulose fibers. Strength-controlling parameters in these webs are influenced by constituent fibers and method of processing and manufacture. Instead of estimating the effect on tensile strength of each processing/manufacturing variable, this study modifies and compares the...
Fault roughness and strength heterogeneity control earthquake size and stress drop
Zielke, Olaf; Galis, Martin; Mai, Paul Martin
2017-01-01
An earthquake's stress drop is related to the frictional breakdown during sliding and constitutes a fundamental quantity of the rupture process. High-speed laboratory friction experiments that emulate the rupture process imply stress drop values
Residual stress effects on the impact resistance and strength of fiber composites
Chamis, C. C.
1973-01-01
Equations have been derived to predict degradation effects of microresidual stresses on impact resistance of unidirectional fiber composites. Equations also predict lamination residual stresses in multilayered angle ply composites.
Kane, Jonathan M
2016-01-01
This is a textbook on proof writing in the area of analysis, balancing a survey of the core concepts of mathematical proof with a tight, rigorous examination of the specific tools needed for an understanding of analysis. Instead of the standard "transition" approach to teaching proofs, wherein students are taught fundamentals of logic, given some common proof strategies such as mathematical induction, and presented with a series of well-written proofs to mimic, this textbook teaches what a student needs to be thinking about when trying to construct a proof. Covering the fundamentals of analysis sufficient for a typical beginning Real Analysis course, it never loses sight of the fact that its primary focus is about proof writing skills. This book aims to give the student precise training in the writing of proofs by explaining exactly what elements make up a correct proof, how one goes about constructing an acceptable proof, and, by learning to recognize a correct proof, how to avoid writing incorrect proofs. T...
Lamothe, Martin; McDuff, Pierre; Pastore, Yves D; Duval, Michel; Sultan, Serge
2018-01-05
To assess the feasibility and acceptability of a mindfulness-based stress reduction (MBSR)-based intervention and determine if the intervention is associated with a significant signal on empathy and emotional competencies. Two pre-post proof-of-concept studies. Participants were recruited at the University of Montreal's Psychology Department (Study 1) and the CHU Sainte-Justine Department of Hematology-Oncology (Study 2). Study 1: 12 students completed the 8-week programme (mean age 24, range 18-34). Study 2: 25 professionals completed the 8-week programme (mean age 48, range 27-63). Standard MBSR programme including 8-week mindfulness programme consisting of 8 consecutive weekly 2-hour sessions and a full-day silent retreat. Mindfulness as measured by the Mindful Attention Awareness Scale; empathy as measured by the Interpersonal Reactivity Index (IRI)'s Perspective Taking and Empathic Concern subscales; identification of one's own emotions and those of others as measured by the Profile of Emotional Competence (PEC)'s Identify my Emotions and Identify Others' Emotions subscales; emotional acceptance as measured by the Acceptance and Action Questionnaire-II (AAQ-II) and the Emotion Regulation Scale (ERQ)'s Expressive Suppression subscale; and recognition of emotions in others as measured by the Geneva Emotion Recognition Test (GERT). In both studies, retention rates (80%-81%) were acceptable. Participants who completed the programme improved on all measures except the PEC's Identify Others' Emotions and the IRI's Empathic Concern (Cohen's d median=0.92, range 45-1.72). In Study 2, favourable effects associated with the programme were maintained over 3 months on the PEC's Identify my Emotions, the AAQ-II, the ERQ's Expressive Suppression and the GERT. The programme was feasible and acceptable. It was associated with a significant signal on the following outcomes: perspective taking, the identification of one's own emotions and emotional acceptance, thus, justifying
Lamothe, Martin; McDuff, Pierre; Pastore, Yves D; Duval, Michel; Sultan, Serge
2018-01-01
Objectives To assess the feasibility and acceptability of a mindfulness-based stress reduction (MBSR)-based intervention and determine if the intervention is associated with a significant signal on empathy and emotional competencies. Design Two pre–post proof-of-concept studies. Setting Participants were recruited at the University of Montreal’s Psychology Department (Study 1) and the CHU Sainte-Justine Department of Hematology-Oncology (Study 2). Participants Study 1: 12 students completed the 8-week programme (mean age 24, range 18–34). Study 2: 25 professionals completed the 8-week programme (mean age 48, range 27–63). Intervention Standard MBSR programme including 8-week mindfulness programme consisting of 8 consecutive weekly 2-hour sessions and a full-day silent retreat. Outcomes measures Mindfulness as measured by the Mindful Attention Awareness Scale; empathy as measured by the Interpersonal Reactivity Index (IRI)’s Perspective Taking and Empathic Concern subscales; identification of one’s own emotions and those of others as measured by the Profile of Emotional Competence (PEC)’s Identify my Emotions and Identify Others’ Emotions subscales; emotional acceptance as measured by the Acceptance and Action Questionnaire-II (AAQ-II) and the Emotion Regulation Scale (ERQ)’s Expressive Suppression subscale; and recognition of emotions in others as measured by the Geneva Emotion Recognition Test (GERT). Results In both studies, retention rates (80%–81%) were acceptable. Participants who completed the programme improved on all measures except the PEC’s Identify Others’ Emotions and the IRI’s Empathic Concern (Cohen’s d median=0.92, range 45–1.72). In Study 2, favourable effects associated with the programme were maintained over 3 months on the PEC’s Identify my Emotions, the AAQ-II, the ERQ’s Expressive Suppression and the GERT. Conclusions The programme was feasible and acceptable. It was associated with a significant signal on the
International Nuclear Information System (INIS)
Matsui, Hiroya
2008-03-01
Within the framework of JAEA's Research and Development on deep geological environments for assessing the safety and reliability of the disposal technology for nuclear waste, this study was conducted to determine the effects of sample damage on the strength obtained from laboratory results (uniaxial compression and Brazilian test). Results of testing on samples of Toki granite taken at Shobasama and at the construction site for the Mizunami Underground Research Laboratory (MIU) at Mizunami, Gifu Pref., Japan, were analysed. Some spatial variation of the results along the boreholes suggested the presence of a correlation between the laboratory strength and the in-situ stresses measured by means of the hydro-fracturing method. To confirm this, numerical analyses of the drilling process in brittle rock by means of a BEM-DDM program (FRACOD 2D ) were carried out to study the induced fracture patterns. These fracture patterns were compared with similar results reported by other published studies and were found to be realistic. The correlation between strength and in-situ stresses could then be exploited to estimate the stresses and the location of core discing observed in boreholes where stress measurements were not available. A correction of the laboratory strength results was also proposed to take into account sample damage during drilling. Modelling of Brazilian tests shows that the calculated fracture patterns determine the strength of the models. This is different from the common assumption that failure occurs when the uniform tensile stress in the sample reaches the tensile strength of the rock material. Based on the modelling results, new Brazilian tests were carried out on samples from borehole MIZ-1 that confirmed the failure mechanism numerically observed. A numerical study of the fracture patterns induced by removal of the overburden on a large scale produces fracture patterns and stress distributions corresponding to observations in crystalline hard rock in
International Nuclear Information System (INIS)
Malzacher, Peter; Manafov, Anar
2010-01-01
PROOF on Demand (PoD) is a set of utilities, which allows starting a PROOF cluster at user request, on any resource management system. It provides a plug-in based system, which allows to use different job submission frontends, such as LSF or gLite WMS. Main components of PoD are the PROOFAgent and the PAConsole. PROOFAgent provides the communication layer between the PROOF master on the local machine and the PROOF workers on the remote resources, possibly behind a firewall. PAConsole provides a user-friendly GUI, which is used to setup, manage, and shutdown the dynamic PROOF cluster. Installation is simple and doesn't require administrator privileges, and all the processes run in user space. PoD gives users, who don't have a centrally-administrated static PROOF cluster at their institute, the possibility to enjoy the full power of interactive analysis with PROOF.
Robinson, J.S; Tanner, D.A
2003-01-01
peer-reviewed Residual stresses develop in the aluminium alloy 7010 when the material is quenched from the solution heat treatment temperature. Residual stress measurements have been made using the X-ray diffraction technique and a longitudinal split sawcut method to determine the magnitude of residual stress that develops in specimens sectioned from large open die forgings as a result of (a) quenching these specimens into water at different temperatures, and (b) cold water quenching from ...
Moyer, P. A.; Boettcher, M. S.; McGuire, J. J.; Collins, J. A.
2017-12-01
During the last five seismic cycles on Gofar transform fault on the East Pacific Rise, the largest earthquakes (6.0 ≤ Mw ≤ 6.2) have repeatedly ruptured the same fault segment (rupture asperity), while intervening fault segments host swarms of microearthquakes. Previous studies on Gofar have shown that these segments of low (≤10%) seismic coupling contain diffuse zones of seismicity and P-wave velocity reduction compared with the rupture asperity; suggesting heterogeneous fault properties control earthquake behavior. We investigate the role systematic differences in material properties have on earthquake rupture along Gofar using waveforms from ocean bottom seismometers that recorded the end of the 2008 Mw 6.0 seismic cycle.We determine stress drop for 117 earthquakes (2.4 ≤ Mw ≤ 4.2) that occurred in and between rupture asperities from corner frequency derived using an empirical Green's function spectral ratio method and seismic moment obtained by fitting the omega-square source model to the low frequency amplitude of earthquake spectra. We find stress drops from 0.03 to 2.7 MPa with significant spatial variation, including 2 times higher average stress drop in the rupture asperity compared to fault segments with low seismic coupling. We interpret an inverse correlation between stress drop and P-wave velocity reduction as the effect of damage on earthquake rupture. Earthquakes with higher stress drops occur in more intact crust of the rupture asperity, while earthquakes with lower stress drops occur in regions of low seismic coupling and reflect lower strength, highly fractured fault zone material. We also observe a temporal control on stress drop consistent with log-time healing following the Mw 6.0 mainshock, suggesting a decrease in stress drop as a result of fault zone damage caused by the large earthquake.
Fear of pain and cortisol reactivity predict the strength of stress-induced hypoalgesia
Timmers, Inge; Kaas, Amanda L.; Quaedflieg, Conny Wem; Biggs, Emma E.; Smeets, Tom; de Jong, Jeroen R.
2018-01-01
BACKGROUND: Acute stress can have an effect on pain sensitivity, yet the direction of the effect - whether it is hypoalgesic or hyperalgesic - is mixed across studies. Moreover, which part of the stress response influences pain sensitivity is still unclear. In the current experimental study, we aim
International Nuclear Information System (INIS)
Ahmad, S.; Bukhari, I.A.
2007-01-01
The shear strength of pre-stressed concrete beams is one of the most important factors to be considered in their design. The available data on shear behavior of pre-tensioned prestressed concrete beams is very limited. In this experimental study, pre-tensioned prestressed concrete I-beams are fabricated with normal and high- strength concretes, varying stirrup spacing and shear span-to-depth ratios. 1Wenty one I-beam specimens that are 300 mm deep and 3745-4960mm long are tested up to failure while deflections, cracking pattern, cracking and failure loads were recorded. The research results are compared with ACI 318-02 and Structure Analysis Program, Response 2000. It was observed that with the decrease in concrete strength, failure mode of prestressed concrete beams changes from flexure shear to web shear cracking for values of shear span-to-depth ratio less than 4.75. Increase in stirrup spacing decreased the effectiveness of stirrups in transmitting shear across crack as a result of which failure mode is changed to web shear cracking especially for beams with lower values of shear span-to-depth ratios. ACI code underestimates the shear carrying capacity of prestressed concrete beams with lower values of shear span- to-depth ratios. Response 2000 can be used more effectively in predicting shear behavior of normal strength prestressed concrete beams. (author)
Manigandan, K.; Srivatsan, T. S.; Tammana, Deepthi; Poorgangi, Behrang; Vasudevan, Vijay K.
2014-05-01
The focus of this technical manuscript is a record of the specific role of microstructure and test specimen orientation on cyclic stress response, cyclic strain resistance, and cyclic stress versus strain response, deformation and fracture behavior of alloy steel 300 M. The cyclic strain amplitude-controlled fatigue properties of this ultra-high strength alloy steel revealed a linear trend for the variation of log elastic strain amplitude with log reversals-to-failure, and log plastic strain amplitude with log reversals-to-failure for both longitudinal and transverse orientations. Test specimens of the longitudinal orientation showed only a marginal improvement over the transverse orientation at equivalent values of plastic strain amplitude. Cyclic stress response revealed a combination of initial hardening for the first few cycles followed by gradual softening for a large portion of fatigue life before culminating in rapid softening prior to catastrophic failure by fracture. Fracture characteristics of test specimens of this alloy steel were different at both the macroscopic and fine microscopic levels over the entire range of cyclic strain amplitudes examined. Both macroscopic and fine microscopic observations revealed fracture to be a combination of both brittle and ductile mechanisms. The underlying mechanisms governing stress response, deformation characteristics, fatigue life, and final fracture behavior are presented and discussed in light of the competing and mutually interactive influences of test specimen orientation, intrinsic microstructural effects, deformation characteristics of the microstructural constituents, cyclic strain amplitude, and response stress.
DEFF Research Database (Denmark)
Mahshid, Rasoul; Hansen, Hans Nørgaard; Loft Højbjerre, Klaus
2016-01-01
Additive manufacturing has shown significant improvement in material and machines for high-quality solid freeform fabrication processes such as selective laser melting (SLM). In particular, manufacturing lattice structures using the SLM procedure is of interest. This research examines the effect...... of cellular materials on compression strength. The specimens are manufactured additively using industrial 3D printing systems from high-strength alloy. The material has the right mechanical properties for manufacturing tool components. This includes samples with solid and lattice structures. The Compression...
International Nuclear Information System (INIS)
Bari, R.A.; Buslik, A.J.; Papazoglou, I.A.
1976-04-01
A critique is presented of the strength-stress overlap method for the reliability of the CRBR primary heat transport system piping. The report addresses, in particular, the reliability assessment of WARD-D-0127 (Piping Integrity Status Report), which is part of the CRBR PSAR docket. It was found that the reliability assessment is extremely sensitive to the assumed shape for the probability density function for the strength (regarded as a random variable) of the cold-leg inlet downcomer section of the primary piping. Based on the rigorous Chebyschev inequality, it is shown that the piping failure probability is less than 10 -2 . On the other hand, it is shown that the failure probability can be much larger than approximately 10 -13 , the typical value put forth in WARD-D-0127
International Nuclear Information System (INIS)
Troshchenko, V.T.; Khamaza, L.A.; Mishchenko, Yu.D.
1978-01-01
A possibility of plotting the fatigue curves for structural elements with stress concentrators was examined according to the results of testing smooth specimens made of 1Kh2M steel. The technique has been suggested, based on using the Neuber formula, while taking into account the dependence of the effective coefficient of stresses concentration on the number of cycles prior to failure. A good agreement between the calculated and the experimental data has been obtained
Effects of low strength pedaling exercise on stress sensitivity and pain threshold
坂野, 裕洋
2017-01-01
This study conducted a comparative assessment of the effects of low intensity lower limb pedaling exercise on the stress sensitivity and pain threshold in healthy subjects and those with chronic stiff neck or lower back pain. The results showed a reduction in pain threshold depending on the applied mechanical stress in both healthy and chronic pain groups. The individuals with chronic pain felt pain more intensely compared to the healthy individuals, and showed a significant reduction in pai...
Directory of Open Access Journals (Sweden)
Hamid Arazi
Full Text Available The aim of this study was to determine the effect of anabolic androgenic steroids (AAS use on oxidative stress responses to a single session of resistance exercise in strength-trained men. Twenty-three strength trained men, with 11 self-reporting regular AAS use and 12 self-reporting never taking AAS (NAAS volunteered to participate in this study. Blood draws were obtained pre and post resistance exercise in order to evaluate changes in oxidative stress biomarkers levels (i.e., 8-hydroxy-2-deoxyguanosine [8-OHdG], malondialdehyde [MDA], and nitric oxide [NO], antioxidant defense systems (i.e., glutathione peroxidase [GPx] and catalase [CAT], and glucose (GLU levels. The AAS users had higher level of 8-OHdG (77.3 ± 17 vs. 57.7 ± 18.2 ng/mg, MDA (85.6 ± 17.8 vs. 52.3 ± 15.1 ng/mL, and GPx (9.1 ± 2.3 vs. 7.1 ± 1.3 mu/mL compared to NAAS at pre exercise (p < 0.05. Both the experimental groups showed increases in 8-OHdG (p = 0.001, MDA (p = 0.001, GPx (p = 0.001, NO (p = 0.04, CAT (p = 0.02 and GLU (p = 0.001 concentrations after resistance exercise, and the AAS group indicated significant differences in 8-OHdG (p = 0.02 and MDA (p = 0.05 concentrations compared with NAAS users at post exercise. In conclusion, use of AAS is associated with alterations in immune function resulting in oxidative stress, and cell damage; however, high-intensity resistance exercise could increase greater oxidative stress biomarkers in strength-trained men. Keywords: ROS, Strength exercise, Anabolic
Stress-deformed state of cylindrical specimens during indirect tensile strength testing
Directory of Open Access Journals (Sweden)
Levan Japaridze
2015-10-01
Full Text Available In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2θ0, and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili's method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear interaction between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.
Nizamuddin, Syed
Glass fiber reinforced vinylester (GFRE) and epoxy (GFRE) pipes have been used for more than three decades to mitigate corrosion problems in oil fields, chemical and industrial plants. In these services, both GFRV and GFRE pipes are exposed to various environmental conditions. Long-term mechanical durability of these pipes after exposure to environmental conditions, which include natural weathering exposure to seasonal temperature variation, sea water, humidity and other corrosive fluids like crude oil, should be well known. Although extensive research has been undertaken, several major issues pertaining to the performance of these pipes under a number of environmental conditions still remain unresolved. The main objective of this study is to investigate the effects of natural weathering, combined natural weathering with seawater and crude oil exposure, for time periods ranging from 3 to 36 months respectively, on the tensile and stress rupture behavior of GFRV and GFRE pipes. Ring specimens are machined from GFRV and GFRE pipes and tested before and after exposure to different weathering conditions prevalent in the eastern region (Dhahran) of Saudi Arabia and present under service conditions. The natural weathering and combined natural weathering with crude oil exposure of GFRV specimens revealed increased tensile strength even after 36 months of exposure when compared with that of the as received samples. However, the combined natural weathering with seawater exposure of GFRV samples revealed better tensile behavior till 24 months of exposure, and after 36 months their tensile strength was seen to be below that of the as received GFRV samples. The stress rupture behavior of natural weather exposed GFRV samples showed an improvement after 12 months of exposure and it decreased after 24 and 36 months of exposure when compared with the as received GFRV samples. The combined natural weathering with crude oil and seawater exposure of GFRV sample revealed improved
Go, D.; Takarada, W.; Kikutani, T.
2017-10-01
The aim of this study was to investigate the mechanism for the improvement of mechanical properties of poly(ethylene terephthalate) (PET) fibers based on the concept of controlling the state of molecular entanglement. For this purpose, five different PET fibers were prepared through either the conventional melt spinning and drawing/annealing process or the high-speed melt spinning process. In both cases, the melt spinning process was designed so as to realize different Deborah number conditions. The prepared fibers were subjected to the laser Raman spectroscopy measurement and the characteristics of the scattering peak at around 1616 cm-1, which corresponds to the C-C/C=C stretching mode of the aromatic ring in the main chain, were investigated in detail. It was revealed that the fibers drawn and annealed after the melt spinning process of lower Deborah number showed higher tensile strength as well as lower value of full width at half maximum (FWHM) in the laser Raman spectrum. Narrow FWHM was considered to represent the homogeneous state of entanglement structure, which may lead to the higher strength and toughness of fibers because individual molecular chains tend to bare similar level of tensile stress when the fiber is stretched. In case of high-speed spun fibers prepared with a high Deborah number condition, the FWHM was narrow presumably because much lower tensile stress in comparison with the drawing/annealing process was applied when the fiber structure was developed, however the value increased significantly upon applying tensile load to the fibers during the laser Raman spectrum measurement. From these results, it was concluded that the Laser Raman spectroscopy could differentiate molecular chain entanglement structure of various fiber samples, in that low FWHM, which corresponds to either homogeneous state of molecular entanglement or lower level of mean residual stress, and small increase of FWTH upon applying tensile stress are considered to be the key
Effects on stress rupture life and tensile strength of tin additions to Inconel 718
Dreshfield, R. L.; Johnson, W.
1982-01-01
Because Inconel 718 represents a major use of columbium and a large potential source of columbium for aerospace alloys could be that of columbium derived from tin slags, the effects of tin additions to Inconel 718 at levels which might be typical of or exceed those anticipated if tin slag derived columbium were used as a melting stock were investigated. Tin was added to 15 pound Inconel 718 heats at levels varying from none added to approximately 10,000 ppm (1 wt%). Limited 1200 F stress rupture testing was performed at stresses from 68,000 to 115,000 psi and a few tensile tests were performed at room temperature, 800 and 1200 F. Additions of tin in excess of 800 ppm were detrimental to ductility and stress rupture life.
International Nuclear Information System (INIS)
Mishima, Yoshitsugu
1983-01-01
In order to obtain public understanding on nuclear power plants, tests should be carried out to prove the reliability and safety of present LWR plants. For example, the aseismicity of nuclear power plants must be verified by using a large scale earthquake simulator. Reliability test began in fiscal 1975, and the proof tests on steam generators and on PWR support and flexure pins against stress corrosion cracking have already been completed, and the results have been internationally highly appreciated. The capacity factor of the nuclear power plant operation in Japan rose to 80% in the summer of 1983, and considering the period of regular inspection, it means the operation of almost full capacity. Japanese LWR technology has now risen to the top place in the world after having overcome the defects. The significance of the reliability test is to secure the functioning till the age limit is reached, to confirm the correct forecast of deteriorating process, to confirm the effectiveness of the remedy to defects and to confirm the accuracy of predicting the behavior of facilities. The reliability of nuclear valves, fuel assemblies, the heat affected zones in welding, reactor cooling pumps and electric instruments has been tested or is being tested. (Kako, I.)
Interpretation of bend strength increase of graphite by the couple-stress theory
International Nuclear Information System (INIS)
Tang, P.Y.
1981-05-01
This paper presents a continued evaluation of the applicability of the couple-stress constitutive theory to graphite. The evaluation is performed by examining four-point bend and uniaxial tensile data of various sized cylindrical and square specimens for three grades of graphites. These data are superficially inconsistent and, usually, at variance with the predictions of classical theories. Nevertheless, this evaluation finds that they can be consistently interpreted by the couple-stress theory. This is compatible with results of an initial evaluation that considered one size of cylindrical specimen for H-451 graphite
Energy Technology Data Exchange (ETDEWEB)
Kusaka, Kazuya, E-mail: kusaka@tokushima-u.ac.jp [Institute of Technology and Science, Tokushima University, 2-1, Minamijosanjima, Tokushima, Tokushima 7708506 (Japan); Maruoka, Yutaka, E-mail: ymaruoka1116@gmail.com [Graduate School of Advanced Technology and Science, Tokushima University, 2-1, Minamijosanjima, Tokushima, Tokushima 7708506 (Japan); Matsue, Tatsuya, E-mail: tmatsue@mat.niihama-nct.ac.jp [Department of Environmental Materials Engineering National Institute of Technology, NIIHAMA College, 7-1, Yakumo-cho, Niihama, Ehime 7928580 (Japan)
2016-05-15
Zinc oxide (ZnO) films were deposited on a soft polyimide sheet substrate by radio frequency sputtering with a ZnO powder target, and the films' crystal orientations and residual stress were investigated using x-ray diffraction as a function of substrate temperature. C-axis oriented ZnO films were achieved using this ZnO powder target method. The ZnO films exhibited high compressive residual stresses between −0.7 and −1.4 GPa. Finally, the authors examined the strength of the obtained film by applying tensile bending loads. No cracks were observed on the surfaces of the ZnO films after a bending test using cylinders with diameters >25 mm. After a bending test using a cylinder with a diameter of 19 mm, large cracks were formed on the films. Therefore, the authors concluded that the tensile bending strength of the obtained films was greater than ∼420 MPa.
Energy Technology Data Exchange (ETDEWEB)
Castano, M.L.; Garcia, M.S.; Diego, G. de; Gomez-Briceno, D. [CIEMAT, Nuclear Fission Department, Structural Materials Program, Avda. Complutense 22, 28040 Madrid (Spain)
2004-07-01
stress corrosion cracking of austenitic stainless steels (SS) and to quantify the effect on the crack propagation rate, an experimental research program was performed using cold and warm worked 304, 316L and 347 SS. Stress corrosion crack growth rate tests, under BWR and PWR environments have been carried out. The results obtained have permitted to determine the yield strength effect in the crack propagation of austenitic stainless steels in PWR and BWR conditions. In addition, similarities on cold work and radiation hardening in enhancing the yield strength and the stress corrosion cracking propagation at high temperature water have been evaluated. (authors)
14 CFR 23.307 - Proof of structure.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Proof of structure. 23.307 Section 23.307... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure General § 23.307 Proof of structure. (a) Compliance with the strength and deformation requirements of § 23.305 must be shown for each...
International Nuclear Information System (INIS)
González Caballero, I; Cuesta Noriega, A; Rodríguez Marrero, A; Fernández del Castillo, E
2012-01-01
The analysis of the complex LHC data usually follows a standard path that aims at minimizing not only the amount of data but also the number of observables used. After a number of steps of slimming and skimming the data, the remaining few terabytes of ROOT files hold a selection of the events and a flat structure for the variables needed that can be more easily inspected and traversed in the final stages of the analysis. PROOF arises at this point as an efficient mechanism to distribute the analysis load by taking advantage of all the cores in modern CPUs through PROOF Lite, or by using PROOF Cluster or PROOF on Demand tools to build dynamic PROOF cluster on computing facilities with spare CPUs. However using PROOF at the level required for a serious analysis introduces some difficulties that may scare new adopters. We have developed the PROOF Analysis Framework (PAF) to facilitate the development of new analysis by uniformly exposing the PROOF related configurations across technologies and by taking care of the routine tasks as much as possible. We describe the details of the PAF implementation as well as how we succeeded in engaging a group of CMS physicists to use PAF as their daily analysis framework.
Deguchi, T.; Kim, H. J.; Ikeda, T.; Yanase, K.
2017-05-01
Because of their excellent mechanical properties, low cost and good workability, the application of ductile cast iron has been increased in various industries such as the automotive, construction and rail industries. For safety designing of the ductile cast iron component, it is necessary to understand the effect of stress ratio, R, on fatigue limit of ductile cast iron in the presence of small defects. Correspondingly in this study, rotating bending fatigue tests at R = -1 and tension-compression fatigue tests at R = -1 and 0.1 were performed by using a ferritic-pearlitic ductile cast iron. To study the effects of small defects, we introduced a small drilled hole at surface of a specimen. The diameter and depth of a drilled hole were 50, 200 and 500 μm, respectively. The non-propagating cracks emanating from graphite particles and holes edge were observed at fatigue limit, irrespective of the value of stress ratio. From the microscopic observation of crack propagation behavior, it can be concluded that the fatigue limit is determined by the threshold condition for propagation of a small crack. It was found that the effect of stress ratio on the fatigue limit of ductile cast iron with small defects can be successfully predicted based on \\sqrt {area} parameter model. Furthermore, a use of the tensile strength, σ B, instead of the Vickers hardness, HV, is effective for fatigue limit prediction.
Sulphide stress corrosion behaviour of a nickel coated high-strength low-alloyed steel
Energy Technology Data Exchange (ETDEWEB)
Salvago, G; Fumagalli, G; Cigada, A; Scolari, P
1987-01-01
The sulphide stress corrosion cracking (SSCC) of the quenched and tempered AISI 4137 H steel either bare or coated with nickel alloys was examined. Both traditional electrochemical and linear elastic fracture mechanics methods were used to examine cracking in the NACE environment and in environments simulating the geothermal fluids found in the area of Larderello in Italy. Some tests were carried out on a geothermal well in Ferrara. High nickel content coatings seem to increase the SSCC resistance of the AISI 4137-H steel. Galvanic couplings effects are possible factors responsible for the behaviour in SSCC.
Stork Color Proofing Technology
Ekman, C. Frederick
1989-04-01
For the past few years, Stork Colorproofing B.V. has been marketing an analog color proofing system in Europe based on electrophoto-graphic technology it pioneered for the purpose of high resolution, high fidelity color imaging in the field of the Graphic Arts. Based in part on this technology, it will make available on a commercial basis a digital color proofing system in 1989. Proofs from both machines will provide an exact reference for the user and will look, feel, and behave in a reproduction sense like the printed press sheet.
Osmotic stress regulates the strength and kinetics of sugar binding to the maltoporin channel
International Nuclear Information System (INIS)
Gurnev, Philip A; Bezrukov, Sergey M; Harries, Daniel; Adrian Parsegian, V
2010-01-01
We study the effect of osmotic stress, exerted by salts, on carbohydrate binding to the sugar-specific bacterial channel maltoporin. When the channel is reconstituted into planar lipid bilayers, single events of its occlusion by sugar are seen as transient interruptions in the flow of small ions. We find that, for most salts, changes in the free energy of maltoporin-sugar binding vary linearly with solution osmotic pressure. Such a change in binding with solution osmolarity indicates that for each salt a constant number of salt-excluding water molecules is released upon sugar-maltoporin association at all salt concentrations. We find that larger numbers of water molecules are released upon binding of the cyclic carbohydrate β-cyclodextrin (CD) than upon binding of the corresponding linear homologue maltoheptaose (m7). Remarkably, the extent to which salts affect the binding constants and rates depends sensitively on the type of salt; dehydration in solutions of different anions corresponds to the Hofmeister series. In sodium sulfate solutions, CD and m7 respectively release about 120 and 35 salt-excluding water molecules; in sodium chloride solutions, 35 and 15 waters. No water release is observed with sodium bromide. Finally, by adding adamantane, known to form an inclusion complex with CD, we can infer that CD not only dehydrates but also undergoes a conformational change upon binding to the channel. As a practical outcome, our results also demonstrate how osmotic stress can improve single-molecule detection of different solutes using protein-based nanopores.
Restoration of strength despite low stress and abnormal imaging after Achilles injury.
Trudel, Guy; Doherty, Geoffrey P; Koike, Yoichi; Ramachandran, Nanthan; Lecompte, Martin; Dinh, Laurent; Uhthoff, Hans K
2009-11-01
To determine the usefulness of clinical imaging in predicting the mechanical properties of rabbit Achilles tendons after acute injury. We created a 2 x 7-mm full-thickness central tendon defect in one Achilles tendon of healthy rabbits. Rabbits in groups of 10 were killed immediately and 4 and 8 wk after surgery (n = 30). We then performed magnetic resonance (MR) imaging, ultrasonography (US), bone mineral densitometry (BMD), and mechanical testing to failure using a dual-cryofixation assembly on experimental and contralateral tendons. The main outcome measures included tendon dimensions, optical density (OD) of T1-weighted, proton density (PD), and T2-weighted MR sequences, US focal abnormalities, BMD of the calcaneus, and stress and peak load to failure. On MR imaging and US, all dimensions of the injured tendons after 2 wk and more were greater than those of the contralateral tendons (P tendons at both 4 wk (39 +/- 9 vs 77 +/- 16 N x mm(-2)) and 8 wk (58 +/- 6 vs 94 +/- 26 N x mm(-2); P tendons, higher T1-weighted OD correlated with lower peak load (r = -0.46; P tendon of lower stress. These findings support progressive physical loading 4 wk after an Achilles tendon injury. T1-weighted OD constituted a marker of tendon mechanical recovery.
Reading the Bible for guidance, comfort, and strength during stressful life events.
Hamilton, Jill B; Moore, Angelo D; Johnson, Khishaana A; Koenig, Harold G
2013-01-01
The use of religious practices to promote mental health among African Americans is well documented. African Americans are more likely to report strong religious affiliations and to use religion over prescribed medications for mental health problems. However, few studies have explored how African Americans use religious practices in response to stressful life events. The aim of this study is to examine how African American women and men find comfort in using scripture passages from The Bible. Fifty-four African American adults residing in the Southeastern United States participated in a qualitative descriptive study using open-ended semistructured interviews. Participants were asked to describe their use of scripture passages from The Bible and the personal meanings associated with these scriptures in the context of a family death or life-threatening illness. These participants used scripture passages categorized as God as Protector, God as Beneficent, Praise and Thanksgiving, God as Healer, Memory of Forefathers, Prayers to God, and Life after Death. Few gender differences were noted. However, women were more likely to use scripture passages of God as Protector and Life after Death, whereas men were more likely to use God as Beneficent and God as Healer. The religious practice of reading scripture passages from The Bible is a mental health-promoting strategy used during stressful life events. The findings of this study have practical uses for nurses and can be used to inform acceptable and sensitive approaches in addressing mental health issues and spiritual care needs in African American patients.
DEFF Research Database (Denmark)
Puech, Matthias
2013-01-01
this correspondence by applying a series of off-the-shelf program transformations à la Danvy et al. on a type checker for the bidirectional λ-calculus, and get a type checker for the λ¯ -calculus, the proof term assignment of LJT. This functional correspondence revisits the relationship between natural deduction......It is well known in proof theory that sequent-calculus proofs differ from natural deduction proofs by “reversing” elimination rules upside down into left introduction rules. It is also well known that to each recursive, functional program corresponds an equivalent iterative, accumulator......-passing program, where the accumulator stores the continuation of the iteration, in “reversed” order. Here, we compose these remarks and show that a restriction of the intuitionistic sequent calculus, LJT, is exactly an accumulator-passing version of intuitionistic natural deduction NJ. More precisely, we obtain...
Proof Auditing Formalised Mathematics
Directory of Open Access Journals (Sweden)
Mark Miles Adams
2016-01-01
Full Text Available The first three formalisations of major mathematical proofs have heralded a new age in formalised mathematics, establishing that informal proofs at the limits of what can be understood by humans can be checked by machine. However, formalisation itself can be subject to error, and yet there is currently no accepted process in checking, or even much concern that such checks have not been performed. In this paper, we motivate why we should be concerned about correctness, and argue the need for proof auditing, to rigorously and independently check a formalisation. We discuss the issues involved in performing an audit, and propose an effective and efficient auditing process. Throughout we use the Flyspeck Project, that formalises the Kepler Conjecture proof, to illustrate our point.
Strahm, Thomas; Studer, Thomas
2016-01-01
The aim of this volume is to collect original contributions by the best specialists from the area of proof theory, constructivity, and computation and discuss recent trends and results in these areas. Some emphasis will be put on ordinal analysis, reductive proof theory, explicit mathematics and type-theoretic formalisms, and abstract computations. The volume is dedicated to the 60th birthday of Professor Gerhard Jäger, who has been instrumental in shaping and promoting logic in Switzerland for the last 25 years. It comprises contributions from the symposium “Advances in Proof Theory”, which was held in Bern in December 2013. Proof theory came into being in the twenties of the last century, when it was inaugurated by David Hilbert in order to secure the foundations of mathematics. It was substantially influenced by Gödel's famous incompleteness theorems of 1930 and Gentzen's new consistency proof for the axiom system of first order number theory in 1936. Today, proof theory is a well-established branch ...
Proofs of Contracted Length Non-covariance
International Nuclear Information System (INIS)
Strel'tsov, V.N.
1994-01-01
Different proofs of contracted length non covariance are discussed. The way based on the establishment of interval inconstancy (dependence on velocity) seems to be the most convincing one. It is stressed that the known non covariance of the electromagnetic field energy and momentum of a moving charge ('the problem 4/3') is a direct consequence of contracted length non covariance. 8 refs
High Load Ratio Fatigue Strength and Mean Stress Evolution of Quenched and Tempered 42CrMo4 Steel
Bertini, Leonardo; Le Bone, Luca; Santus, Ciro; Chiesi, Francesco; Tognarelli, Leonardo
2017-08-01
The fatigue strength at a high number of cycles with initial elastic-plastic behavior was experimentally investigated on quenched and tempered 42CrMo4 steel. Fatigue tests on unnotched specimens were performed both under load and strain controls, by imposing various levels of amplitude and with several high load ratios. Different ratcheting and relaxation trends, with significant effects on fatigue, are observed and discussed, and then reported in the Haigh diagram, highlighting a clear correlation with the Smith-Watson-Topper model. High load ratio tests were also conducted on notched specimens with C (blunt) and V (sharp) geometries. A Chaboche model with three parameter couples was proposed by fitting plain specimen cyclic and relaxation tests, and then finite element analyses were performed to simulate the notched specimen test results. A significant stress relaxation at the notch root became clearly evident by reporting the numerical results in the Haigh diagram, thus explaining the low mean stress sensitivity of the notched specimens.
Maternal obesity and perinatal oxidative stress: the strength of the association.
Negro, S; Boutsikou, T; Briana, D D; Tataranno, M L; Longini, M; Proietti, F; Bazzini, F; Dani, C; Malamitsi-Puchner, A; Buonocore, G; Perrone, S
2017-01-01
Maternal obesity is a chronic inflammatory state, which has been shown to induce increased levels of free fatty acids, reactive oxygen species and inflammatory cells. Recent evidence reveals increased levels of lipid peroxidation products in the plasma of obese women during pregnancy. The aim of this study was to test the hypothesis that maternal overweight or obesity is associated with increased oxidative stress (OS) in offspring. Two hundred and forty-five pregnant women and their newborns were prospectively enrolled. Mothers were divided in two groups: lean control - LC (n=175, Group I); overweight or obese (n=70, Group II) according to BMI ≥ 25 before pregnancy. Cord blood F2-isoprostanes (F2-IsoPs), as reliable markers of OS, were measured in all newborns. Lower 1 minute APGAR score and higher weight at discharge were found in Group II neonates, compared to those of Group I (p less than 0.05). Small for gestational age (SGA) newborns of both groups showed increased levels of F2-IsoPs than appropriate (AGA) or large (LGA) for gestational age (GA) (p less than 0.01). SGA newborns of Group II had higher F2-IsoPs levels compared to SGA of Group I (p less than 0.01), which were significantly correlated to maternal BMI at the end of pregnancy (r=0.451, p less than 0.01). Multivariate regression analysis corrected for confounding factors, showed that maternal overweight or obesity was significantly associated with high F2-IsoPs levels in SGA offspring (p less than 0.01). Maternal overweight or obesity is associated with increased OS in their SGA newborns. Data suggest the need of antioxidant protection for both mothers during pregnancy and infants soon after birth.
Proof Nets for Lambek Calculus
Roorda, Dirk
1992-01-01
The proof nets of linear logic are adapted to the non-commutative Lambek calculus. A different criterion for soundness of proof nets is given, which gives rise to new algorithms for proof search. The order sensitiveness of the Lambek calculus is reflected by the planarity condition on proof nets;
Energy Technology Data Exchange (ETDEWEB)
Schmitt, Marcus [AREVA NP GmbH, Erlangen (Germany)
2013-07-01
Even before the Fukushima event occurred some German nuclear power plants (NPP) have considered flooding scenarios. As a result of one of these studies, AREVA performed an upgrade project in NPP Isar 1 with flood-proof motors as a replacement of existing air-cooled low-voltage and high-voltage motors of the emergency cooling chain. After the Fukushima event, in which the cooling chains failed, the topic flood-proof equipment gets more and more into focus. This compact will introduce different kinds of flood-proof electrical motors which are currently installed or planned for installation into NPPs over the world. Moreover the process of qualification, as it was performed during the project in NPP Isar 1, will be shown. (orig.)
International Nuclear Information System (INIS)
Schmitt, Marcus
2013-01-01
Even before the Fukushima event occurred some German nuclear power plants (NPP) have considered flooding scenarios. As a result of one of these studies, AREVA performed an upgrade project in NPP Isar 1 with flood-proof motors as a replacement of existing air-cooled low-voltage and high-voltage motors of the emergency cooling chain. After the Fukushima event, in which the cooling chains failed, the topic flood-proof equipment gets more and more into focus. This compact will introduce different kinds of flood-proof electrical motors which are currently installed or planned for installation into NPPs over the world. Moreover the process of qualification, as it was performed during the project in NPP Isar 1, will be shown. (orig.)
We report the effect of glass fiber structure and the epoxy polymer system on the flexural strength, interlaminar shear stress (ILSS), and energy absorption properties of glass fiber-reinforced polymer (GFRP) composites. Four different GFRP composites were fabricated from two glass fiber textiles of...
de Bruin, Esther I.; Formsma, Anne R.; Frijstein, Gerard; Bögels, Susan M.
2017-01-01
Work-related stress and associated illness and burnout is rising in western society, with now as much as almost a quarter of European and half of USA's employees estimated to be at the point of burnout. Mindfulness meditation, yoga, and physical exercise have all shown beneficial effects for
de Bruin, E.I.; Formsma, A.R.; Frijstein, G.; Bögels, S.M.
2017-01-01
Work-related stress and associated illness and burnout is rising in western society, with now as much as almost a quarter of European and half of USA’s employees estimated to be at the point of burnout. Mindfulness meditation, yoga, and physical exercise have all shown beneficial effects for
Woods-Giscombé, Cheryl L; Black, Angela R
2010-12-14
In the current article, the authors examine the potential role of mind-body interventions for preventing or reducing health disparities in a specific group-African American women. The authors first discuss how health disparities affect this group, including empirical evidence regarding the influence of biopsychosocial processes (e.g., psychological stress and social context) on disparate health outcomes. They also detail how African American women's unique stress experiences as a result of distinct sociohistorical and cultural experiences related to race and gender potentially widen exposure to stressors and influence stress responses and coping behaviors. Using two independent, but related, frameworks (Superwoman Schema [SWS] and the Strong Black Woman Script [SBW-S]), they discuss how, for African American women, stress is affected by "strength" (vis-à-vis resilience, fortitude, and self-sufficiency) and the emergent health-compromising behaviors related to strength (e.g., emotional suppression, extraordinary caregiving, and self-care postponement). The authors then describe the potential utility of three mind-body interventions-mindfulness-based stress reduction (MBSR), loving-kindness meditation (LKM), and NTU psychotherapy-for specifically targeting the stress-, strength-, and contextually related factors that are thought to influence disparate outcomes for African American women. Self-awareness, self-care, inter- and intrapersonal restorative healing and a redefinition of inner strength may manifest through developing a mindfulness practice to decrease stress-related responses; using LKM to cultivate compassion and forgiveness for self and others; and the balance of independence and interdependence as a grounding NTU principle for redefining strength. The authors conclude with a discussion of potential benefits for integrating key aspects of the interventions with recommendations for future research.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 5. Gödel's Proof - Incompleteness Theorems. S M Srivastava. General Article Volume 12 Issue 5 May 2007 pp 71-84. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/012/05/0071-0084. Keywords.
Visualizing Probabilistic Proof
Guerra-Pujol, Enrique
2015-01-01
The author revisits the Blue Bus Problem, a famous thought-experiment in law involving probabilistic proof, and presents simple Bayesian solutions to different versions of the blue bus hypothetical. In addition, the author expresses his solutions in standard and visual formats, i.e. in terms of probabilities and natural frequencies.
Weber, Keith
2010-01-01
Many mathematics educators have noted that mathematicians do not only read proofs to gain conviction but also to obtain insight. The goal of this article is to discuss what this insight is from mathematicians' perspective. Based on interviews with nine research-active mathematicians, two sources of insight are discussed. The first is reading a…
Proof in geometry with "mistakes in geometric proofs"
Fetisov, A I
2006-01-01
This single-volume compilation of 2 books explores the construction of geometric proofs. It offers useful criteria for determining correctness and presents examples of faulty proofs that illustrate common errors. 1963 editions.
Proofs without Words: A Visual Application of Reasoning and Proof
Bell, Carol J.
2011-01-01
Reasoning and Proof is one of the Process Standards set forth in National Council of Teachers of Mathematics' (NCTM) "Principles and Standards for School Mathematics." Thus, it is important to give students opportunities to build their reasoning skills and aid their understanding of the proof process. Teaching students how to do proofs is a…
Directory of Open Access Journals (Sweden)
Yousef Askari Dolatabad
2018-06-01
Full Text Available The use of un-bonded tendons is prevalent in post-tensioned concrete structures. Equations for prediction of stress in un-bonded tendons of post-tensioned normal (vibrating concrete flexural members have been given in various codes. They are based on experience and don’t account all of important parameters such as concrete strength (normal and high strength and its type (vibrating and non-vibrating concrete. Since self-compacting concrete (SCC is nearly a new innovation therefore, understanding the implementation of this type of non-vibrating concrete on the ultimate unbonded tendon stress is critical. For this aim, in this paper there are presented experimental results of six continuous un-bonded post-tensioned I-beams in two groups were casted and monitored by different electrical strain gauges. In the first tested group, the beams (UPN1-12, UPN1-18, UPN1-22 were consisting of high strength normal concrete (HSNC where as in the second group (UPS1-12, UPS1-18, UPS1-22 high strength self-compacting concrete (HSSCC were tested. The variables included the type of concrete and percentage of bounded non-prestressed steel. Experimental monitored results of ultimate stress increase in unbonded tendons are compared with predicted equations of different researchers and standards. It was found that, the proposed equation is in better agreement with the test results. The results of standard error of estimate Sy/x, indicates that for two types of HSCs, the ACI 318-2011 provides better estimates than AASHTO-2010 model whereas this model provides better estimates than BS 8110-97. Keywords: Post-tensioned, Unbonded tendons, Stress increase, High strength normal and self-compacting concrete, Continuous beams
International Nuclear Information System (INIS)
Stepanov, I.A.
1994-01-01
The properties of a constructional material determining life are strength, plasticity, and crack resistance. Loss of properties occurs as the result of corrosion, temperature action, actual and residual stresses, and neutron and gamma-radiation. Corrosion leads to a decrease in thickness, loss of density, changes in the composition and structure of the surface layers, and a reduction in strength, plasticity, and crack resistance of constructional materials. The influence of temperature on the loss of properties of materials is revealed as possible phase and structural transformations of the metal and the surface layers and a reduction in the stress-rupture, plastic, and thermal-fatigue properties. The actual and residual stresses not only strengthen the influence of corrosive media but also directly determine the stress-rupture strength and cyclic life. The influence of neutron and gamma-radiation is based o the change in composition of the corrosive medium (radiolysis), radiation embrittlement of the material, and the change in properties of the surface and oxide layers. The authors discuss the concepts and design of automated monitoring systems for determining the fitness of the components of on atomic power plant
Czech Academy of Sciences Publication Activity Database
Jeřábek, Emil
2012-01-01
Roč. 58, č. 3 (2012), s. 177-187 ISSN 0942-5616 R&D Projects: GA AV ČR IAA100190902; GA MŠk(CZ) 1M0545 Institutional support: RVO:67985840 Keywords : proof complexity * monotone sequent calculus Subject RIV: BA - General Mathematics Impact factor: 0.376, year: 2012 http://onlinelibrary.wiley.com/doi/10.1002/malq.201020071/full
International Nuclear Information System (INIS)
Peregrin, Jaroslav
2007-01-01
The usual way of interpreting Goedel's (1931) incompleteness result is as showing that there is a gap between truth and provability, i.e. that we can never prove everything that is true. Moreover, this result is supposed to show that there are unprovable truths which we can know to be true. This, so the story goes, shows that we are more than machines that are restricted to acting as proof systems. Hence our minds are 'not mechanical'
Yoshida, Keisuke; Saito, Tatsuhiko; Urata, Yumi; Asano, Youichi; Hasegawa, Akira
2017-12-01
In this study, we investigated temporal variations in stress drop and b-value in the earthquake swarm that occurred at the Yamagata-Fukushima border, NE Japan, after the 2011 Tohoku-Oki earthquake. In this swarm, frictional strengths were estimated to have changed with time due to fluid diffusion. We first estimated the source spectra for 1,800 earthquakes with 2.0 ≤ MJMA < 3.0, by correcting the site-amplification and attenuation effects determined using both S waves and coda waves. We then determined corner frequency assuming the omega-square model and estimated stress drop for 1,693 earthquakes. We found that the estimated stress drops tended to have values of 1-4 MPa and that stress drops significantly changed with time. In particular, the estimated stress drops were very small at the beginning, and increased with time for 50 days. Similar temporal changes were obtained for b-value; the b-value was very high (b 2) at the beginning, and decreased with time, becoming approximately constant (b 1) after 50 days. Patterns of temporal changes in stress drop and b-value were similar to the patterns for frictional strength and earthquake occurrence rate, suggesting that the change in frictional strength due to migrating fluid not only triggered the swarm activity but also affected earthquake and seismicity characteristics. The estimated high Q-1 value, as well as the hypocenter migration, supports the presence of fluid, and its role in the generation and physical characteristics of the swarm.
International Nuclear Information System (INIS)
Giginyak, F.F.; Dragunov, Yu.G.; Mozharovskaya, T.N.; Titov, V.F.
1993-01-01
The results of the experimental investigations into creep and long-term strength of heat-resistant steels 15Kh2MFA and 15Kh2NMFA in the initial state and after heat-treatment simulating the metal irradiation embrittlement at the end of the product service date under static loading at the complex stress state and at high temperatures are presented. The experimentally substantiated equations of state describing creep and long-term stability of materials taking into account the type of the stress state are derived. (author)
Energy Technology Data Exchange (ETDEWEB)
Liu, Y., E-mail: troy.liu@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Bhamji, I., E-mail: imran.bhamji@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Withers, P.J., E-mail: p.j.withers@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom); Wolfe, D.E., E-mail: dew125@arl.psu.edu [The Pennsylvania State University, University Park, State College, PA 16801 (United States); Motta, A.T., E-mail: atmnuc@engr.psu.edu [The Pennsylvania State University, University Park, State College, PA 16801 (United States); Preuss, M., E-mail: michael.preuss@manchester.ac.uk [Materials Performance Centre, School of Materials, The University of Manchester, M13 9PL (United Kingdom)
2015-11-15
This paper investigates the residual stresses and interfacial shear strength of a TiAlN coating on Zr–Nb–Sn–Fe alloy (ZIRLO™) substrate designed to improve corrosion resistance of fuel cladding used in water-cooled nuclear reactors, both during normal and exceptional conditions, e.g. a loss of coolant event (LOCA). The distribution and maximum value of the interfacial shear strength has been estimated using a modified shear-lag model. The parameters critical to this analysis were determined experimentally. From these input parameters the interfacial shear strength between the TiAlN coating and ZIRLO™ substrate was inferred to be around 120 MPa. It is worth noting that the apparent strength of the coating is high (∼3.4 GPa). However, this is predominantly due to the large compressive residuals stress (3 GPa in compression), which must be overcome for the coating to fail in tension, which happens at a load just 150 MPa in excess of this.
An evaluation of the pressure proof test concept for 2024-T3 aluminium alloy sheet
Dawicke, D. S.; Poe, C. C., Jr.; Newman, J. C.; Harris, C. E.
1991-01-01
The concept of pressure proof testing of fuselage structures with fatigue cracks to insure structural integrity was evaluated from a fracture mechanics viewpoint. A generic analytical and experimental investigation was conducted on uniaxially loaded flat panels with crack configurations and stress levels typical of longitudinal lap splice joints in commercial transport aircraft fuselages. The results revealed that the remaining fatigue life after a proof cycle was longer than that without the proof cycle because of crack growth retardation due to increased crack closure. However, based on a crack length that is slightly less than the critical value at the maximum proof stress, the minimum assured life or proof test interval must be no more than 550 pressure cycles for a 1.33 proof factor and 1530 pressure cycles for a 1.5 proof factor to prevent in-flight failures.
ZERODUR: deterministic approach for strength design
Hartmann, Peter
2012-12-01
There is an increasing request for zero expansion glass ceramic ZERODUR substrates being capable of enduring higher operational static loads or accelerations. The integrity of structures such as optical or mechanical elements for satellites surviving rocket launches, filigree lightweight mirrors, wobbling mirrors, and reticle and wafer stages in microlithography must be guaranteed with low failure probability. Their design requires statistically relevant strength data. The traditional approach using the statistical two-parameter Weibull distribution suffered from two problems. The data sets were too small to obtain distribution parameters with sufficient accuracy and also too small to decide on the validity of the model. This holds especially for the low failure probability levels that are required for reliable applications. Extrapolation to 0.1% failure probability and below led to design strengths so low that higher load applications seemed to be not feasible. New data have been collected with numbers per set large enough to enable tests on the applicability of the three-parameter Weibull distribution. This distribution revealed to provide much better fitting of the data. Moreover it delivers a lower threshold value, which means a minimum value for breakage stress, allowing of removing statistical uncertainty by introducing a deterministic method to calculate design strength. Considerations taken from the theory of fracture mechanics as have been proven to be reliable with proof test qualifications of delicate structures made from brittle materials enable including fatigue due to stress corrosion in a straight forward way. With the formulae derived, either lifetime can be calculated from given stress or allowable stress from minimum required lifetime. The data, distributions, and design strength calculations for several practically relevant surface conditions of ZERODUR are given. The values obtained are significantly higher than those resulting from the two
Analogy, explanation, and proof
Hummel, John E.; Licato, John; Bringsjord, Selmer
2014-01-01
People are habitual explanation generators. At its most mundane, our propensity to explain allows us to infer that we should not drink milk that smells sour; at the other extreme, it allows us to establish facts (e.g., theorems in mathematical logic) whose truth was not even known prior to the existence of the explanation (proof). What do the cognitive operations underlying the inference that the milk is sour have in common with the proof that, say, the square root of two is irrational? Our ability to generate explanations bears striking similarities to our ability to make analogies. Both reflect a capacity to generate inferences and generalizations that go beyond the featural similarities between a novel problem and familiar problems in terms of which the novel problem may be understood. However, a notable difference between analogy-making and explanation-generation is that the former is a process in which a single source situation is used to reason about a single target, whereas the latter often requires the reasoner to integrate multiple sources of knowledge. This seemingly small difference poses a challenge to the task of marshaling our understanding of analogical reasoning to understanding explanation. We describe a model of explanation, derived from a model of analogy, adapted to permit systematic violations of this one-to-one mapping constraint. Simulation results demonstrate that the resulting model can generate explanations for novel explananda and that, like the explanations generated by human reasoners, these explanations vary in their coherence. PMID:25414655
Aigner, Martin
2014-01-01
This revised and enlarged fifth edition features four new chapters, which contain highly original and delightful proofs for classics such as the spectral theorem from linear algebra, some more recent jewels like the non-existence of the Borromean rings and other surprises. From the Reviews "... Inside PFTB (Proofs from The Book) is indeed a glimpse of mathematical heaven, where clever insights and beautiful ideas combine in astonishing and glorious ways. There is vast wealth within its pages, one gem after another. ... Aigner and Ziegler... write: "... all we offer is the examples that we have selected, hoping that our readers will share our enthusiasm about brilliant ideas, clever insights and wonderful observations." I do. ... " Notices of the AMS, August 1999 "... This book is a pleasure to hold and to look at: ample margins, nice photos, instructive pictures, and beautiful drawings ... It is a pleasure to read as well: the style is clear and entertaining, the level is close to elementary, the necessary b...
International Nuclear Information System (INIS)
Behrenhoff, W; Ehrenfeld, W; Samson, J; Stadie, H
2011-01-01
The 'parallel ROOT facility' (PROOF) from the ROOT framework provides a mechanism to distribute the load of interactive and non-interactive ROOT sessions on a set of worker nodes optimising the overall execution time. While PROOF is designed to work on a dedicated PROOF cluster, the benefits of PROOF can also be used on top of another batch scheduling system with the help of temporary per user PROOF clusters. We will present a lightweight tool which starts a temporary PROOF cluster on a SGE based batch cluster or, via a plugin mechanism, e.g. on a set of bare desktops via ssh. Further, we will present the result of benchmarks which compare the data throughput for different data storage back ends available at the German National Analysis Facility (NAF) at DESY.
Algebraic proofs over noncommutative formulas
Czech Academy of Sciences Publication Activity Database
Tzameret, Iddo
2011-01-01
Roč. 209, č. 10 (2011), s. 1269-1292 ISSN 0890-5401 R&D Projects: GA MŠk LC505 Institutional research plan: CEZ:AV0Z10190503 Keywords : proof complexity * algebraic proof system s * frege proofs Subject RIV: BA - General Mathematics Impact factor: 0.560, year: 2011 http://www.sciencedirect.com/science/article/pii/S089054011100109X
Florio, C S
2018-06-01
A computational model was used to compare the local bone strengthening effectiveness of various isometric exercises that may reduce the likelihood of distal tibial stress fractures. The developed model predicts local endosteal and periosteal cortical accretion and resorption based on relative local and global measures of the tibial stress state and its surface variation. Using a multisegment 3-dimensional leg model, tibia shape adaptations due to 33 combinations of hip, knee, and ankle joint angles and the direction of a single or sequential series of generated isometric resultant forces were predicted. The maximum stress at a common fracture-prone region in each optimized geometry was compared under likely stress fracture-inducing midstance jogging conditions. No direct correlations were found between stress reductions over an initially uniform circular hollow cylindrical geometry under these critical design conditions and the exercise-based sets of active muscles, joint angles, or individual muscle force and local stress magnitudes. Additionally, typically favorable increases in cross-sectional geometric measures did not guarantee stress decreases at these locations. Instead, tibial stress distributions under the exercise conditions best predicted strengthening ability. Exercises producing larger anterior distal stresses created optimized tibia shapes that better resisted the high midstance jogging bending stresses. Bent leg configurations generating anteriorly directed or inferiorly directed resultant forces created favorable adaptations. None of the studied loads produced by a straight leg was significantly advantageous. These predictions and the insight gained can provide preliminary guidance in the screening and development of targeted bone strengthening techniques for those susceptible to distal tibial stress fractures. Copyright © 2018 John Wiley & Sons, Ltd.
Tamper proofing of safeguards monitors
International Nuclear Information System (INIS)
Riley, R.J.
1982-11-01
The tamper proofing of safeguards monitors is essential if the data they produce is, and can be seen to be, reliable. This report discusses the problem of tamper proofing and gives guidance on when and how to apply tamper proofing techniques. The report is split into two parts. The first concerns the fundamental problem of how much tamper proofing to apply and the second describes methods of tamper proofing and discusses their usefulness. Both sections are applicable to all safeguards monitors although particular reference will be made to doorway monitors in some cases. The phrase 'tamper proofing' is somewhat misleading as it is impossible to completely tamper proof any device. Given enough time and resources, even the most elaborate tamper proofing can be overcome. In safeguards applications we are more interested in making the device tamper resistant and tamper indicating. That is, it should be able to resist a certain amount of tampering, and if tampering proves successful, that fact should be immediately obvious. Techniques of making a device tamper indicating and tamper resistant will be described below. The phrase tamper proofing will be used throughout this report as a generic term, including both tamper resistance and tamper indicating. (author)
International Nuclear Information System (INIS)
Harada, Y.; Maruyama, Y.; Chino, E.; Shibazaki, H.; Kudo, T.; Hidaka, A.; Hashimoto, K.; Sugimoto, J.
2000-01-01
The analytical study on severe accident shows the possibility of the reactor coolant system (RCS) piping failure before reactor pressure vessel failure under the high primary pressure sequence at pressurized water reactors. The establishment of the high-temperature strength model of the realistic RCS piping materials is important in order to predict precisely the accident progression and to evaluate the piping behavior with small uncertainties. Based on material testing, the 0.2% proof stress and the ultimate tensile strength above 800degC were given by the equations of second degree as a function of the reciprocal absolute temperature considering the strength increase due to fine precipitates for the piping materials. The piping materials include type 316 stainless steel, type 316 stainless steel of nuclear grade, CF8M cast duplex stainless steel and STS410 carbon steel. Also the short-term creep rupture time and the minimum creep rate at high-temperature were given by the modified Norton's Law as a function of stress and temperature considering the effect of the precipitation formation and resolution on the creep strength. The present modified Norton's Law gives better results than the conventional Larson-Miller method. Correlating the creep data (the applied stress versus the minimum creep rate) with the tensile data (the 0.2% proof stress or the ultimate tensile strength versus the strain rate), it was found that the dynamic recrystallization significantly occurred at high-temperature. (author)
A proof of the conformal collider bounds
Energy Technology Data Exchange (ETDEWEB)
Hofman, Diego M. [Institute for Theoretical Physics, University of Amsterdam, Science Park 904, Postbus 94485, 1090 GL, Amsterdam (Netherlands); Li, Daliang [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Meltzer, David [Department of Physics, Yale University, New Haven, CT 06511 (United States); Poland, David [Department of Physics, Yale University, New Haven, CT 06511 (United States); School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540 (United States); Rejon-Barrera, Fernando [Institute for Theoretical Physics, University of Amsterdam, Science Park 904, Postbus 94485, 1090 GL, Amsterdam (Netherlands)
2016-06-20
In this paper, we prove that the “conformal collider bounds” originally proposed in http://dx.doi.org/10.1088/1126-6708/2008/05/012 hold for any unitary parity-preserving conformal field theory (CFT) with a unique stress tensor in dimensions d≥3. In particular this implies that the ratio of central charges for a unitary 4d CFT lies in the interval (31/18)≥(a/c)≥(1/3). For superconformal theories this is further reduced to (3/2)≥(a/c)≥(1/2). The proof relies only on CFT first principles — in particular, bootstrap methods — and thus constitutes the first complete field theory proof of these bounds. We further elaborate on similar bounds for non-conserved currents and relate them to results obtained recently from deep inelastic scattering.
Experimental determination of the micro-scale strength and stress-strain relation of an epoxy resin
DEFF Research Database (Denmark)
Zike, Sanita; Sørensen, Bent F.; Mikkelsen, Lars Pilgaard
2016-01-01
An approach is developed for determining the stress-strain law and a failure stress appropriate for micro-mechanical models of polymer materials. Double cantilever beam test specimens, made of an epoxy polymer with notches having finite root radius, were subjected to pure bending moments in an en......An approach is developed for determining the stress-strain law and a failure stress appropriate for micro-mechanical models of polymer materials. Double cantilever beam test specimens, made of an epoxy polymer with notches having finite root radius, were subjected to pure bending moments......-scale (5–6%). The hardening exponent of a power law hardening material was obtained by the use of the J-integral, estimating the strain energy density around the notch. The hardening exponent was found to be within the range of 5–6 and the corresponding micro-scale failure stress was in the range of 220...
Kissoudis, Christos; Wiel, van de Clemens; Visser, R.G.F.; Linden, van der Gerard
2016-01-01
Breeding for stress-resilient crops strongly depends on technological and biological advancements that have provided a wealth of information on genetic variants and their contribution to stress tolerance. In the context of the upcoming challenges for agriculture due to climate change, such as
Zhu, Min; Du, Cuiwei; Li, Xiaogang; Liu, Zhiyong; Wang, Shengrong; Zhao, Tianliang; Jia, Jinghuan
2014-04-01
The stress corrosion cracking (SCC) behaviors and mechanisms of X80 pipeline steels with different strength and microstructure in high pH carbonate/bicarbonate solution were investigated by slow strain rate testing and electrochemical test. The results showed that the cracking mode of low strength X80 steel composed of bulky polygonal ferrite and granular bainite in high pH solution was intergranular (IGSCC), and the SCC mechanism was anodic dissolution (AD). While the mixed cracking mode of high strength X80 steel consisted of fine acicular ferrite and granular bainite was intergranular (IGSCC) in the early stage, and transgranular (TGSCC) in the later stage. The decrease of pH value of crack tip was probably the key reason for the occurrence of TGSCC. The SCC mechanism may be a mixed mode of AD and hydrogen embrittlement (HE), and the HE mechanism may play a significant role in the deep crack propagation at the later stage. The cracking modes and SCC mechanisms of the two X80 steels were associated with its microstructure and strength.
Analogy, Explanation, and Proof
Directory of Open Access Journals (Sweden)
John eHummel
2014-11-01
Full Text Available People are habitual explanation generators. At its most mundane, our propensity to explain allows us to infer that we should not drink milk that smells sour; at the other extreme, it allows us to establish facts (e.g., theorems in mathematical logic whose truth was not even known prior to the existence of the explanation (proof. What do the cognitive operations underlying the (inductive inference that the milk is sour have in common with the (deductive proof that, say, the square root of two is irrational? Our ability to generate explanations bears striking similarities to our ability to make analogies. Both reflect a capacity to generate inferences and generalizations that go beyond the featural similarities between a novel problem and familiar problems in terms of which the novel problem may be understood. However, a notable difference between analogy-making and explanation-generation is that the former is a process in which a single source situation is used to reason about a single target, whereas the latter often requires the reasoner to integrate multiple sources of knowledge. This small-seeming difference poses a challenge to the task of marshaling our understanding of analogical reasoning in the service of understanding explanation. We describe a model of explanation, derived from a model of analogy, adapted to permit systematic violations of this one-to-one mapping constraint. Simulation results demonstrate that the resulting model can generate explanations for novel explananda and that, like the explanations generated by human reasoners, these explanations vary in their coherence.
Characteristics of structural loess strength and preliminary framework for joint strength formula
Rong-jian Li; Jun-ding Liu; Rui Yan; Wen Zheng; Sheng-jun Shao
2014-01-01
The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress (Kf line), and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests: the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural lo...
International Nuclear Information System (INIS)
Niemann, R.C.; Gonczy, J.D.; Hoffman, J.A.; Mataya, K.F.; Smelser, P.; Young, W.C.
1979-01-01
A support system utilizing epoxy fiberglass tension members will be used for the UTSI Superconducting Dipole Magnet. Elements of a support system have a basic member which is a link in which a composite is wound around a mandrel. This element uses the strength of the material fibers in a most advantageous way. The flexural and torsional load imputs to the link at its end must be minimized. A spherical bearing with a cylindrical outer surface functions as the central pin. Experience gained in the application with emphasis on tension member material, ultimate strength, creep, and heat intercepts is presented
International Nuclear Information System (INIS)
Aschl, H.; Stoeckl, S.
1981-01-01
At the Institut fuer Massivbau of the Technical University of Munich testing machines were built, which allow to test sealed and unsealed cylinders with uniaxial stress state at elevated temperatures till 523 K (250 0 C). With this equipment tests were carried out at predried, unsealed and sealed specimens to study - thermal expansion coefficient - modulus of elasticity - shrinkage and - creep of concrete at elevated temperatures of 353 K (80 0 C) and 393 K (120 0 C) and at a normal temperature of 293 K (20 0 C). In addition the residual strength of all specimens was measured. In the worst case (unsealed, i.e. drying specimens) some showed a maximum decrease in strength up to 60%. (orig.) [de
Investigations on evaluation method for yield strength of round bar undermatched joint
International Nuclear Information System (INIS)
Matsumoto, Toshimi; Satoh, Hiroshi; Wadayama, Yoshihide
1988-01-01
The objective values of the yield strength and fracture toughness are respectively more than 1200 MPa and 200 MPa √m at 4K on the structural material for the superconducting magnet container in the Fusion Reactor. It should be desirable to assure the above value for the properties of the weld metal used for the containers. The initial yielding behavior of the undermatched joint is investigated in this paper. Results are as follows. (1) On the nominal stress vs. nominal strain relationship at the central section of the undermatched metal of the joint, the stress increases higher than the yield stress of undermatched metal itself then gradually comes up to a constant value, after the whole area of the undermatched metal starts to generate plastic deformation as the stress reaches the yield stress of the metal. (2) The increase in the stress is caused by the restraint effect of the base metal on the plasticity, and the stress becomes larger with the larger strength ratio of the undermatched metal to the basemetal and with the smaller relative thickness of the joint. (3) The strain does not distribute uniformly at the central section of the undermatched metal along the radial direction during the initial yielding process of the joint. (4) In the case that the yield strength of the joints is considered as the proof stress desided for a constant offset strain, the relationship between the dimensionless yield strength of the joint to the yield stress of the base metal and the relative yield strength of the undermatched metal to the base metal cannot be not established consistently. (5) The assumption that the base metal is rigid, causes the excessive evaluation of the joint yield strength of theoretical analysis. (6) As the quantitative evaluation method, the stress vs. strain relationship and then the algebraic expression has been formulated for the initial yielding behavior of the joint. (author)
Short proofs of strong normalization
Wojdyga, Aleksander
2008-01-01
This paper presents simple, syntactic strong normalization proofs for the simply-typed lambda-calculus and the polymorphic lambda-calculus (system F) with the full set of logical connectives, and all the permutative reductions. The normalization proofs use translations of terms and types to systems, for which strong normalization property is known.
From Inductive Reasoning to Proof
Yopp, David A.
2009-01-01
Mathematical proof is an expression of deductive reasoning (drawing conclusions from previous assertions). However, it is often inductive reasoning (conclusions drawn on the basis of examples) that helps learners form their deductive arguments, or proof. In addition, not all inductive arguments generate more formal arguments. This article draws a…
2008-09-01
In recent years, several research projects have been conducted to study the feasibility of increasing the allowable : compressive stress in concrete at prestress transfer, currently defined as 0.60f'ci in the AASHTO LRFD Bridge : Design Specification...
2017-02-17
incipient damage nucleation and growth , is that which comprises a local neighbor- hood of grains. Heterogeneities in the local intergranular stresses and...After yielding, there was a small drop in the flow stress to 525 MPa followed by work hardening to 535 MPa by the end of the test. Overall, the...collected on a large panel area detector that was located 756 mm downstream of the sample. The detector was a GE amorphous silicon area detector with 2048
International Nuclear Information System (INIS)
Mozharovskaya, T.N.
1984-01-01
A programme and procedure are given to study 08Kh18N9 steel at 600 deg C and 15Kh2MFA steel at 550 deg C for creep and long-term strength at different parameters of proportional loading as well as at different parameters under loading in two-link irregular trajectories. This makes it possible to estimate the effect of the kind of a stress deviator, history and prehistory of loading on plastic deformation in creep and on failure under long-term loading
Energy Technology Data Exchange (ETDEWEB)
Mozharovskaya, T N [AN Ukrainskoj SSR, Kiev. Inst. Problem Prochnosti
1984-11-01
A programme and procedure are given to study 08Kh18N9 steel at 600 deg C and 15Kh2MFA steel at 550 deg C for creep and long-term strength at different parameters of proportional loading as well as at different parameters under loading in two-link irregular trajectories. This makes it possible to estimate the effect of the kind of a stress deviator, history and prehistory of loading on plastic deformation in creep and on failure under long-term loading.
DEFF Research Database (Denmark)
Schürmann, Carsten
2009-01-01
for programming language theory. Most logical frameworks are based on constructive type theories, such as Isabelle (on the simply-typed λ-calculus), LF [HHP93] (on the dependently typed λ-calculus), and LLF (on a linearly typed λ-calculus). The representational strength of the logical framework stems from...
Bicalho, Aline Aredes; de Souza, Silas Júnior Boaventura; de Rosatto, Camila Maria Peres; Tantbirojn, Daranee; Versluis, Antheunis; Soares, Carlos José
2015-12-01
Evaluate the effect of environment on post-gel shrinkage (Shr), cuspal strains (CS), microtensile bond strength (μTBS), elastic modulus (E) and shrinkage stress in molars with large class II restorations. Sixty human molars received standardized Class II mesio-oclusal-distal cavity preparations. Restorations were made with two composites (CHA, Charisma Diamond, Heraus Kulzer and IPS Empress Direct, Ivoclar-Vivadent) using three environment conditions (22°C/50% humidity, 37°C/50% humidity and 37°C/90% humidity) simulated in custom developed chamber. Shr was measured using the strain gauge technique (n=10). CS was measured using strain gauges. Half of the teeth (n=5) were used to assess the elastic modulus (E) and Knoop hardness (KHN) at different depths using microhardness indentation. The other half (n=5) was used to measure the μTBS. The composites and environment conditions were simulated in a two-dimensional finite element analysis of a tooth restoration. Polymerization shrinkage was modeled using Shr data. The Shr, CS, μTBS, KHN and E data were statistically analyzed using two-way ANOVA and Tukey test (significance level: 0.05). Both composites had similar Shr, CS, μTBS and shrinkage stress. CHA had higher elastic modulus than IPS. Increasing temperature and humidity significantly increased Shr, CS and shrinkage stress. μTBS were similar for groups with lower humidity, irrespective of temperature, and higher with higher humidity. E and KHN were constant through the depth for CHA. E and KHN values were affected by environment only for IPS, mainly deeper in the cavity. Shrinkage stress at dentin/composite interface had high inverse correlation with μTBS. Shrinkage stress in enamel had high correlation with CS. Increasing temperature and humidity caused higher post-gel shrinkage and cusp deformation with higher shrinkage stresses in the tooth structure and tooth/restoration interface for both composites tested. The chamber developed for simulating the
International Nuclear Information System (INIS)
Kul'chitskij, N.M.; Troshchenko, A.V.; Koval'chuk, B.I.; Khamaza, L.A.; Nikolaev, I.A.
1982-01-01
The paper is concerned with choice of conditions for preliminary cyclic block loading, determination of fatigue failure resistance characteristics for various structural materials under regular and selected block loading, investigation of the preliminary cyclic loading effect on regularities of elastoplastic deformation of materials concerned in the biaxial stressed state. Under selected conditions of cyclic block loading the character of damage accumulation is close to the linear law for the materials of high-srength doped steel, and VT6 alloys of concern. These materials in the initial state and after preliminary cyclic loading are anisotropic. Axial direction is characterized by a higher plastic strain resistance for steel and tangential direction - for VT6 alloy. The generalized strain curves for the materials in question are not invariant as to the stressed state type. It is stated that the effect of preliminary unsteady cyclic loading on resistance and general regularities of material deformation in the complex stressed state is insignificant. It is observed that stress-strain properties of the materials tend to vary in the following way: plastic strain resistance of the steel lowers and that of VT6 rises, anisotropy of the materials somehow decreases. The variation in the material anisotropy may be attributed to a decrease in residual stresses resulting from preliminary cyclic loading
Directory of Open Access Journals (Sweden)
Szeptyński P.
2017-06-01
Full Text Available A general proposition of an energy-based limit condition for anisotropic materials exhibiting strength-differential effect (SDE based on spectral decomposition of elasticity tensors and the use of scaling pressure-dependent functions is specified for the case of orthotropic materials. A detailed algorithm (based on classical solutions of cubic equations for the determination of elastic eigenstates and eigenvalues of the orthotropic stiffness tensor is presented. A yield condition is formulated for both two-dimensional and three-dimensional cases. Explicit formulas based on simple strength tests are derived for parameters of criterion in the plane case. The application of both criteria for the description of yielding and plastic deformation of metal sheets is discussed in detail. The plane case criterion is verified with experimental results from the literature.
International Nuclear Information System (INIS)
Lee, Woo Yong; Koh, Seong Ung; Kim, Kyoo Young
2005-01-01
The purpose of this work is to understand the effect of Mo addition on SSC susceptibility of high strength low alloy steels in terms of microstructure and corrosion property. Materials used in this study are high strength low alloy (HSLA) steels with carbon content of 0.04wt% and Mo content varying from 0.1 to 0.3wt%. The corrosion property of steels was evaluated by immersion test in NACE-TM01-77 solution A and by analyzing the growth behavior of surface corrosion products. SSC resistance of steels was evaluated using constant load test. Electrochemical test was performed to investigate initial corrosion rate. Addition of Mo increased corrosion rate of steels by enhancing the porosity of surface corrosion products. however, corrosion rate was not directly related to SSC susceptibility of steels
Directory of Open Access Journals (Sweden)
Suresh Mitthra
2017-01-01
Full Text Available Background: Understanding the mechanical properties is important in predicting the clinical behavior of composites. Finite element analysis (FEA evaluates properties of materials replicating clinical scenario. Aim: This study evaluated polymerization shrinkage and stress, wear resistance (WR, and compressive strength (CS of silorane in comparison with two methacrylate resins. Settings and Design: This study design was a numerical study using FEA. Materials and Methods: Three-dimensional (3D models of maxillary premolar with Class I cavities (2 mm depth, 4 mm length, and 2.5 mm width created and restored with silorane, nanohybrid, and microhybrid; Groups I, II, and III, respectively. Loads of 200–600 N were applied. Polymerization shrinkage was first determined by displacement produced in the X, Y, and Z planes. Maximum stress distribution due to shrinkage was calculated using AN SYS software. 3D cube models of composite resins were simulated with varying filler particle size. Similar loads were applied. WR and compressive stress were calculated: K W L/H and load/cross-sectional area, respectively. Statistical analysis done using one-way ANOVA, Kruskal–Wallis, and Tukey's honestly significant difference test (P < 0.05. Results: Polymerization shrinkage (0.99% and shrinkage stress (233.21 Mpa of silorane were less compared to microhybrid (2.14% and 472.43 Mpa and nanohybrid (2.32% and 464.88 Mpa. Silorane (7.92×/1011 μm/mm3 and nanohybrid (7.79×/1011 showed superior WR than microhybrid (1.113×/1017. There was no significant difference in compressive stress among the groups. Conclusion: Silorane exhibited less polymerization shrinkage and shrinkage stress compared to methacrylates. Silorane and nanohybrid showed greater WR compared to microhybrid. CS of all groups was similar.
... can be life-saving. But chronic stress can cause both physical and mental harm. There are at least three different types of stress: Routine stress related to the pressures of work, family, and other daily responsibilities Stress brought about ...
International Nuclear Information System (INIS)
Sitko, E.
1995-01-01
It has been found out that 30HGSNA steel undergo cracking under action of stresses in aqueous solutions containing oxygen, while it show high resistance in deoxidated solutions. The purpose of such phenomena is the existence of sulfur inclusions in steel which are a centers of denting corrosion. That points acting as a stresses concentrators where pH factor decreases including hydrogen formation and its absorption in the metal. That mechanism is the main purpose of brittle steel cracking observed in oxygen rich solutions. (author)
Proof assistants: History, ideas and future
Indian Academy of Sciences (India)
application is and will be in computer supported modelling and verification of sys- tems. But there is still ... Introduction ... compute with them, but their main focus is on doing proofs. ..... Proof development in a type theory based proof assistant.
Lee, Juhwa; Hwang, Jeongho; Bae, Dongho
2018-03-01
In this paper, welding residual stress analysis and fatigue strength assessment were performed at elevated temperature for multi-pass dissimilar material weld between Alloy 617 and P92 steel, which are used in thermal power plant. Multi-pass welding between Alloy 617 and P92 steel was performed under optimized welding condition determined from repeated pre-test welding. In particular, for improving dissimilar material weld-ability, the buttering welding technique was applied on the P92 steel side before multi-pass welding. Welding residual stress distribution at the dissimilar material weld joint was numerically analyzed by using the finite element method, and compared with experimental results which were obtained by the hole-drilling method. Additionally, fatigue strength of dissimilar material weld joint was assessed at the room temperature (R.T), 300, 500, and 700 °C. In finite element analysis results, numerical peak values; longitudinal (410 MPa), transverse (345 MPa) were higher than those of experiments; longitudinal (298 MPa), transverse (245 MPa). There are quantitatively big differences between numerical and experimental results, due to some assumption about the thermal conductivity, specific heat, effects of enforced convection of the molten pool, dilution, and volume change during phase transformation caused by actual shield gas. The low fatigue limit at R.T, 300 °C, 500 °C and 700 °C was assessed to be 368, 276, 173 and 137 MPa respectively.
Lee, Juhwa; Hwang, Jeongho; Bae, Dongho
2018-07-01
In this paper, welding residual stress analysis and fatigue strength assessment were performed at elevated temperature for multi-pass dissimilar material weld between Alloy 617 and P92 steel, which are used in thermal power plant. Multi-pass welding between Alloy 617 and P92 steel was performed under optimized welding condition determined from repeated pre-test welding. In particular, for improving dissimilar material weld-ability, the buttering welding technique was applied on the P92 steel side before multi-pass welding. Welding residual stress distribution at the dissimilar material weld joint was numerically analyzed by using the finite element method, and compared with experimental results which were obtained by the hole-drilling method. Additionally, fatigue strength of dissimilar material weld joint was assessed at the room temperature (R.T), 300, 500, and 700 °C. In finite element analysis results, numerical peak values; longitudinal (410 MPa), transverse (345 MPa) were higher than those of experiments; longitudinal (298 MPa), transverse (245 MPa). There are quantitatively big differences between numerical and experimental results, due to some assumption about the thermal conductivity, specific heat, effects of enforced convection of the molten pool, dilution, and volume change during phase transformation caused by actual shield gas. The low fatigue limit at R.T, 300 °C, 500 °C and 700 °C was assessed to be 368, 276, 173 and 137 MPa respectively.
Liu, Yiming; Shi, Yimin; Bai, Xuchao; Zhan, Pei
2018-01-01
In this paper, we study the estimation for the reliability of a multicomponent system, named N- M-cold-standby redundancy system, based on progressive Type-II censoring sample. In the system, there are N subsystems consisting of M statistically independent distributed strength components, and only one of these subsystems works under the impact of stresses at a time and the others remain as standbys. Whenever the working subsystem fails, one from the standbys takes its place. The system fails when the entire subsystems fail. It is supposed that the underlying distributions of random strength and stress both belong to the generalized half-logistic distribution with different shape parameter. The reliability of the system is estimated by using both classical and Bayesian statistical inference. Uniformly minimum variance unbiased estimator and maximum likelihood estimator for the reliability of the system are derived. Under squared error loss function, the exact expression of the Bayes estimator for the reliability of the system is developed by using the Gauss hypergeometric function. The asymptotic confidence interval and corresponding coverage probabilities are derived based on both the Fisher and the observed information matrices. The approximate highest probability density credible interval is constructed by using Monte Carlo method. Monte Carlo simulations are performed to compare the performances of the proposed reliability estimators. A real data set is also analyzed for an illustration of the findings.
Burdens of Proof, Presumptions and Standards of Proof in Criminal ...
African Journals Online (AJOL)
Worku_Y
evidential and persuasive burdens of proof as between the state and the ..... scholars have observed that the evidential burden is a function of the burden of ..... required to convince judges by creating such an intensity of belief in their minds.
Proust: A Nano Proof Assistant
Directory of Open Access Journals (Sweden)
Prabhakar Ragde
2016-11-01
Full Text Available Proust is a small Racket program offering rudimentary interactive assistance in the development of verified proofs for propositional and predicate logic. It is constructed in stages, some of which are done by students before using it to complete proof exercises, and in parallel with the study of its theoretical underpinnings, including elements of Martin-Lof type theory. The goal is twofold: to demystify some of the machinery behind full-featured proof assistants such as Coq and Agda, and to better integrate the study of formal logic with other core elements of an undergraduate computer science curriculum.
Pinar, Ali; Coskun, Zeynep; Mert, Aydin; Kalafat, Dogan
2015-04-01
The general consensus based on historical earthquake data point out that the last major moment release on the Prince's islands fault was in 1766 which in turn signals an increased seismic risk for Istanbul Metropolitan area considering the fact that most of the 20 mm/yr GPS derived slip rate for the region is accommodated mostly by that fault segment. The orientation of the Prince's islands fault segment overlaps with the NW-SE direction of the maximum principle stress axis derived from the focal mechanism solutions of the large and moderate sized earthquakes occurred in the Marmara region. As such, the NW-SE trending fault segment translates the motion between the two E-W trending branches of the North Anatolian fault zone; one extending from the Gulf of Izmit towards Çınarcık basin and the other extending between offshore Bakırköy and Silivri. The basic relation between the orientation of the maximum and minimum principal stress axes, the shear and normal stresses, and the orientation of a fault provides clue on the strength of a fault, i.e., its frictional coefficient. Here, the angle between the fault normal and maximum compressive stress axis is a key parameter where fault normal and fault parallel maximum compressive stress might be a necessary and sufficient condition for a creeping event. That relation also implies that when the trend of the sigma-1 axis is close to the strike of the fault the shear stress acting on the fault plane approaches zero. On the other hand, the ratio between the shear and normal stresses acting on a fault plane is proportional to the coefficient of frictional coefficient of the fault. Accordingly, the geometry between the Prince's islands fault segment and a maximum principal stress axis matches a weak fault model. In the frame of the presentation we analyze seismological data acquired in Marmara region and interpret the results in conjuction with the above mentioned weak fault model.
Complex proofs of real theorems
Lax, Peter D
2011-01-01
Complex Proofs of Real Theorems is an extended meditation on Hadamard's famous dictum, "The shortest and best way between two truths of the real domain often passes through the imaginary one." Directed at an audience acquainted with analysis at the first year graduate level, it aims at illustrating how complex variables can be used to provide quick and efficient proofs of a wide variety of important results in such areas of analysis as approximation theory, operator theory, harmonic analysis, and complex dynamics. Topics discussed include weighted approximation on the line, Müntz's theorem, Toeplitz operators, Beurling's theorem on the invariant spaces of the shift operator, prediction theory, the Riesz convexity theorem, the Paley-Wiener theorem, the Titchmarsh convolution theorem, the Gleason-Kahane-Żelazko theorem, and the Fatou-Julia-Baker theorem. The discussion begins with the world's shortest proof of the fundamental theorem of algebra and concludes with Newman's almost effortless proof of the prime ...
Lin, Lianghua; Liu, Zhiyi; Ying, Puyou; Liu, Meng
2015-12-01
Multi-step heat treatment effectively enhances the stress corrosion cracking (SCC) resistance but usually degrades the mechanical properties of Al-Zn-Mg-Cu alloys. With the aim to enhance SCC resistance as well as strength of Al-Zn-Mg-Cu alloys, we have optimized the process parameters during two-step aging of Al-6.1Zn-2.8Mg-1.9Cu alloy by Taguchi's L9 orthogonal array. In this work, analysis of variance (ANOVA) was performed to find out the significant heat treatment parameters. The slow strain rate testing combined with scanning electron microscope and transmission electron microscope was employed to study the SCC behaviors of Al-Zn-Mg-Cu alloy. Results showed that the contour map produced by ANOVA offered a reliable reference for selection of optimum heat treatment parameters. By using this method, a desired combination of mechanical performances and SCC resistance was obtained.
Energy Technology Data Exchange (ETDEWEB)
Iza-Mendia, A., E-mail: aiza@ceit.es [CEIT and Tecnun (University of Navarra), Manuel de Lardizabal 15, 20018 Donostia-San Sebastian, Basque Country (Spain); Gutierrez, I. [CEIT and Tecnun (University of Navarra), Manuel de Lardizabal 15, 20018 Donostia-San Sebastian, Basque Country (Spain)
2013-01-20
A series of available equations allows the yield and the tensile strength of low carbon ferrite-pearlite microstructures to be expressed as a function of the optical grain size, steel composition and interstitials in solution. Over the years, as the complexity of steel microstructures has increased, some additional terms have been added to account for precipitation and forest dislocation contributions. In theory, this opens the door for an extension of these equations to bainitic microstructures. Nevertheless, there is a series of difficulties that needs to be overcome in order to improve prediction accuracy. In the present work, different microstructures (ferrite-pearlite, bainite, quenched, and quenched and tempered) were produced and tension tested in a C-Mn-Nb steel. Optical microscopy and EBSD (Electron Back Scattered Diffraction) were applied and the results were compared as a function of the tolerance angle. Based on this work, an adaptation to Pickering's equation is proposed, including its extension to other microstructures rather than ferrite-pearlite.
Calibration Device Designed for proof ring used in SCC Experiment
Hu, X. Y.; Kang, Z. Y.; Yu, Y. L.
2017-11-01
In this paper, a calibration device for proof ring used in SCC (Stress Corrosion Cracking) experiment was designed. A compact size loading device was developed to replace traditional force standard machine or a long screw nut. The deformation of the proof ring was measured by a CCD (Charge-Coupled Device) during the calibration instead of digital caliper or a dial gauge. The calibration device was verified at laboratory that the precision of force loading is ±0.1% and the precision of deformation measurement is ±0.002mm.
International Nuclear Information System (INIS)
Doh, Jaeh Yeok; Lee, Jong Soo; Lee, Seung Uk
2016-01-01
In this study, a Back-propagation neural network (BPN) is employed to conduct an approximation of a true stress-strain curve using the load-displacement experimental data of DP590, a high-strength material used in automobile bodies and chassis. The optimized interconnection weights are obtained with hidden layers and output layers of the BPN through intelligent learning and training of the experimental data; by using these weights, a mathematical model of the material's behavior is suggested through this feed-forward neural network. Generally, the material properties from the tensile test cannot be acquired until the fracture regions, since it is difficult to measure the cross-section area of a specimen after diffusion necking. For this reason, the plastic properties of the true stress-strain are extrapolated using the weighted-average method after diffusion necking. The accuracies of BPN-based meta-models for predicting material properties are validated in terms of the Root mean square error (RMSE). By applying the approximate material properties, the reliable finite element solution can be obtained to realize the different shapes of the finite element models. Furthermore, the sensitivity analysis of the approximate meta-model is performed using the first-order approximate derivatives of the BPN and is compared with the results of the finite difference method. In addition, we predict the tension velocity's effect on the material property through a first-order sensitivity analysis.
Fatigue assessment of laserbeam welded PM steel components by the notch stress approach
Energy Technology Data Exchange (ETDEWEB)
Waterkotte, R. [Schaeffler Technologies GmbH and Co. KG, Herzogenaurach (Germany); Sonsino, C.M. [Fraunhofer Institute for Structural Durability and System Reliability LBF, Darmstadt (Germany); Baumgartner, J.
2011-10-15
The local fatigue strength of a laserbeam weld of a complex engine component, which joins a PM with a formed sheet component, was assessed by the notch stress concept with the fictitious reference radius of r{sub ref}= 0.05 mm. First, simplified specimens, following the main geometric dimensions of the parts, were manufactured. On these specimens the fatigue strength was identified by tests and the notch stresses calculated by finite element analysis. Based on these results a design SN-curve was derived to assess the fatigue strength of the engine component. The numerical assessment of the welded joint was verified by proof tests with the component. The assessment could be improved by considering statistical and stress gradient dependent size effects according to the concept of the highly stressed volume. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
... taking care of an aging parent. With mental stress, the body pumps out hormones to no avail. Neither fighting ... with type 1 diabetes. This difference makes sense. Stress blocks the body from releasing insulin in people with type 2 ...
Proof Rules for Recursive Procedures
Hesselink, Wim H.
1993-01-01
Four proof rules for recursive procedures in a Pascal-like language are presented. The main rule deals with total correctness and is based on results of Gries and Martin. The rule is easier to apply than Martin's. It is introduced as an extension of a specification format for Pascal-procedures, with
Barberà, Salvador, 1946-
2010-01-01
This paper surveys the literature on strategy-proofness from a historical perspective. While I discuss the connections with other works on incentives in mechanism design, the main emphasis is on social choice models. This article has been prepared for the Handbook of Social Choice and Welfare, Volume 2, Edited by K. Arrow, A. Sen and K. Suzumura
Computerized Proof Techniques for Undergraduates
Smith, Christopher J.; Tefera, Akalu; Zeleke, Aklilu
2012-01-01
The use of computer algebra systems such as Maple and Mathematica is becoming increasingly important and widespread in mathematics learning, teaching and research. In this article, we present computerized proof techniques of Gosper, Wilf-Zeilberger and Zeilberger that can be used for enhancing the teaching and learning of topics in discrete…
IFA proof of principle experiments
International Nuclear Information System (INIS)
Olson, C.L.
1979-01-01
IFA proof of principle experiments is discussed. Controlled beam front motion experiments are reported, which demonstrate that accurate IFA programming of the motion of the potential well at the head of an IREB has been achieved. The status of IFA ion experiments is also discussed
Effect of applied stress on the compressive residual stress introduced by laser peening
International Nuclear Information System (INIS)
Sumiya, Rie; Tazawa, Toshiyuki; Narazaki, Chihiro; Saito, Toshiyuki; Kishimoto, Kikuo
2016-01-01
Peening is the process which is able to be generated compressive residual stress and is known to be effective for preventing SCC initiation and improvement of fatigue strength. Laser peening is used for the nuclear power plant components in order to prevent SCC initiation. Although it is reported that the compressive residual stress decreases due to applied stresses under general operating condition, the change of residual stress might be large under excessive loading such as an earthquake. The objectives of this study are to evaluate the relaxation behavior of the compressive residual stress due to laser peening and to confirm the surface residual stress after loading. Therefore laser peened round bar test specimens of SUS316L which is used for the reactor internals of nuclear power plant were loaded at room temperature and elevated temperature and then surface residual stresses were measured by X-ray diffraction method. In the results of this test, it was confirmed that the compressive residual stress remained after applying uniform stress larger than 0.2% proof stress, and the effect of cyclic loading on the residual stress was small. The effect of applying compressive stress on the residual stress relaxation was confirmed to be less than that of applying tensile stress. Plastic deformation through a whole cross section causes the change in the residual stress distribution. As a result, the surface compressive residual stress is released. It was shown that the effect of specimen size on residual stress relaxation and the residual stress relaxation behavior in the stress concentration region can be explained by assumed stress relaxation mechanism. (author)
Proof testing of an explosion containment vessel
Energy Technology Data Exchange (ETDEWEB)
Esparza, E.D. [Esparza (Edward D.), San Antonio, TX (United States); Stacy, H.; Wackerle, J. [Los Alamos National Lab., NM (United States)
1996-10-01
A steel containment vessel was fabricated and proof tested for use by the Los Alamos National Laboratory at their M-9 facility. The HY-100 steel vessel was designed to provide total containment for high explosives tests up to 22 lb (10 kg) of TNT equivalent. The vessel was fabricated from an 11.5-ft diameter cylindrical shell, 1.5 in thick, and 2:1 elliptical ends, 2 in thick. Prior to delivery and acceptance, three types of tests were required for proof testing the vessel: a hydrostatic pressure test, air leak tests, and two full design charge explosion tests. The hydrostatic pressure test provided an initial static check on the capacity of the vessel and functioning of the strain instrumentation. The pneumatic air leak tests were performed before, in between, and after the explosion tests. After three smaller preliminary charge tests, the full design charge weight explosion tests demonstrated that no yielding occurred in the vessel at its rated capacity. The blast pressures generated by the explosions and the dynamic response of the vessel were measured and recorded with 33 strain channels, 4 blast pressure channels, 2 gas pressure channels, and 3 displacement channels. This paper presents an overview of the test program, a short summary of the methodology used to predict the design blast loads, a brief description of the transducer locations and measurement systems, some of the hydrostatic test strain and stress results, examples of the explosion pressure and dynamic strain data, and some comparisons of the measured data with the design loads and stresses on the vessel.
Energy Technology Data Exchange (ETDEWEB)
Furue, H.; Nonaka, K. [Mechanical Engineering Lab., Tsukuba, Ibaraki (Japan)
1996-01-15
Thermoplastics are often reinforced with short fibers with aims of improvement of their strengths, rigidities and hardness or maintenance of their dimensional stabilities. Such short fiber reinforced plastic materials have more expectation for high performance plastics. Authors already examined of some effects of reinforced fiber and of orientation in injection molding on flexural fatigue characteristics of the injection-molded high performance thermoplastic materials. However, the examination of short fiber reinforced effects on fatigue strength characteristics was not always sufficient. In this study, in order to obtain a guiding principle for fatigue resistant design of the short fiber reinforced injection molding materials, polyethersulfones (PES) was examined on its tensile fatigue strength and an effect of short fiber reinforcement for improvement of its fundamental dynamic properties on its fatigue characteristics. Especially, its fatigue life characteristics was elucidated mainly on relationship of mean stress, stress amplitude and number of repeating fracture in tensile fatigue behavior. 10 refs., 15 figs., 2 tabs.
An Architecture for Proof Planning Systems
Dennis, Louise Abigail
2005-01-01
This paper presents a generic architecture for proof planning systems in terms of an interaction between a customisable proof module and search module. These refer to both global and local information contained in reasoning states.
compressive and flexural strength of cement mortar stabilized with ...
African Journals Online (AJOL)
PROF. BARTH EKWEME
concrete. However, plain mortar materials are usually brittle and often crack more easily and fail more suddenly than ... impact strength, higher elastic modulus, better sound proofness ..... in Concrete. Unpublished Ph.D. Thesis, Department.
Focused labeled proof systems for modal logic
Miller , Dale; Volpe , Marco
2015-01-01
International audience; Focused proofs are sequent calculus proofs that group inference rules into alternating positive and negative phases. These phases can then be used to define macro-level inference rules from Gentzen's original and tiny introduction and structural rules. We show here that the inference rules of labeled proof systems for modal logics can similarly be described as pairs of such phases within the LKF focused proof system for first-order classical logic. We consider the syst...
Directory of Open Access Journals (Sweden)
Pooya Hamdi
2015-12-01
Full Text Available Heterogeneity is an inherent component of rock and may be present in different forms including mineral heterogeneity, geometrical heterogeneity, weak grain boundaries and micro-defects. Microcracks are usually observed in crystalline rocks in two forms: natural and stress-induced; the amount of stress-induced microcracking increases with depth and in-situ stress. Laboratory results indicate that the physical properties of rocks such as strength, deformability, P-wave velocity and permeability are influenced by increase in microcrack intensity. In this study, the finite-discrete element method (FDEM is used to model microcrack heterogeneity by introducing into a model sample sets of microcracks using the proposed micro discrete fracture network (μDFN approach. The characteristics of the microcracks required to create μDFN models are obtained through image analyses of thin sections of Lac du Bonnet granite adopted from published literature. A suite of two-dimensional laboratory tests including uniaxial, triaxial compression and Brazilian tests is simulated and the results are compared with laboratory data. The FDEM-μDFN models indicate that micro-heterogeneity has a profound influence on both the mechanical behavior and resultant fracture pattern. An increase in the microcrack intensity leads to a reduction in the strength of the sample and changes the character of the rock strength envelope. Spalling and axial splitting dominate the failure mode at low confinement while shear failure is the dominant failure mode at high confinement. Numerical results from simulated compression tests show that microcracking reduces the cohesive component of strength alone, and the frictional strength component remains unaffected. Results from simulated Brazilian tests show that the tensile strength is influenced by the presence of microcracks, with a reduction in tensile strength as microcrack intensity increases. The importance of microcrack heterogeneity in
Koplin, Julian J; Selgelid, Michael J
2015-11-01
A common strategy in bioethics is to posit a prima facie case in favour of one policy, and to then claim that the burden of proof (that this policy should be rejected) falls on those with opposing views. If the burden of proof is not met, it is claimed, then the policy in question should be accepted. This article illustrates, and critically evaluates, examples of this strategy in debates about the sale of organs by living donors, human enhancement, and the precautionary principle. We highlight general problems with this style of argument, and particular problems with its use in specific cases. We conclude that the burden ultimately falls on decision-makers (i.e. policy-makers) to choose the policy supported by the best reasons. © 2015 John Wiley & Sons Ltd.
Future-proofing nursing education.
Keighley, Tom
2014-12-01
The origin of future-proofing seems lost in the mists of recent history. Dictionaries date its use from about 1991, referring to the prevention of obsolescence in information technology manufacturing and occasionally in organizational systems. However, closer analysis in healthcare demonstrates it can be traced back to the Rand Corporation and the studies commissioned there in the 1960s. These aimed at identifying the predictive factors in planning healthcare, including development of the workforce. It is a managerial concept that helps to project a vision of change that is not simply reactive or short-term. It permits a focus on leadership and the maximising of learning opportunities and includes analysis of the policy horizon. It held within it an assumption about the importance of establishing the cognitive frameworks that would influence long-term behaviours and not focus simply on short-term gains. This paper utilises this approach to explore options for future-proofing of nurse education.
Student Teachers’ Proof Schemes on Proof Tasks Involving Inequality: Deductive or Inductive?
Rosyidi, A. H.; Kohar, A. W.
2018-01-01
Exploring student teachers’ proof ability is crucial as it is important for improving the quality of their learning process and help their future students learn how to construct a proof. Hence, this study aims at exploring at the proof schemes of student teachers in the beginning of their studies. Data were collected from 130 proofs resulted by 65 Indonesian student teachers on two proof tasks involving algebraic inequality. To analyse, the proofs were classified into the refined proof schemes level proposed by Lee (2016) ranging from inductive, which only provides irrelevant inferences, to deductive proofs, which consider addressing formal representation. Findings present several examples of each of Lee’s level on the student teachers’ proofs spanning from irrelevant inferences, novice use of examples or logical reasoning, strategic use examples for reasoning, deductive inferences with major and minor logical coherence, and deductive proof with informal and formal representation. Besides, it was also found that more than half of the students’ proofs coded as inductive schemes, which does not meet the requirement for doing the proof for the proof tasks examined in this study. This study suggests teacher educators in teacher colleges to reform the curriculum regarding proof learning which can accommodate the improvement of student teachers’ proving ability from inductive to deductive proof as well from informal to formal proof.
2010-10-01
... 49 Transportation 3 2010-10-01 2010-10-01 false Strength test requirements for steel pipeline to...: MINIMUM FEDERAL SAFETY STANDARDS Test Requirements § 192.505 Strength test requirements for steel pipeline... as provided in paragraph (e) of this section, the strength test must be conducted by maintaining the...
Energy Technology Data Exchange (ETDEWEB)
Berglin, Leif [Siemens Industrial Turbomachinery AB, Finspaang (Sweden)
2005-04-01
Strength data are missing for braze joints. Repaired components cannot fully make use of the strength of the braze, and lifetime will be underestimated. The goal of the project was to generate material data to be able to prolong the lifetime of the components. Two different material combinations were tested, 12% Chromium steel brazed with BNi-2, and a nickel base alloy, IN792 brazed with BNi-5. Tensile testing at room temperature and elevated temperature was performed in the project. Target group is purchasers and suppliers of repaired components. A tensile test specimen with butt joint was developed in the project. The used test specimen worked well for the 12% Chromium steel. The results from testing show that proof stress and tensile strength are strongly depending on the joint gap, particularly at room temperature. High strength, close to base material strength, was achieved with joint gaps smaller than 50{mu}m. For wider joint gaps, strength was lower. Strength was approximately 25% of base material strength for joint gaps over 100{mu}m. The results can be explained by changes in microstructure. Joint gaps wider than 50{mu}m showed evidence of two-phase structure. At 500 deg C, the results also showed a connection between joint gap, microstructure and strength. The generated strength data can be used for calculations of lifetime for repaired components. Two different process errors were discovered in the manufacturing process of the brazed IN792 test specimens. The generated material data are therefor erroneous. The reason for this was two manufacturing errors. The tack welding was done with too high heat input. The surfaces of the joint gap became oxidised and the oxide hindered wetting of the braze. The second reason was that the brazing was done without the prescribed hold time at maximum temperature. The melting of the braze was therefor not completed when cooling started. As a result, the strength of the IN792 specimens was low at both temperatures.
DEFF Research Database (Denmark)
Keller, Hanne Dauer
2015-01-01
Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....
Fledderus, M.
2012-01-01
Twee op de vijf UT-studenten hebben last van ernstige studiestress, zo erg zelfs dat het ze in hun privéleven belemmert. Die cijfers komen overeen met het landelijk beeld van stress onder studenten. Samen met 14 andere universiteits- en hogeschoolbladen enquêteerde UT Nieuws bijna 5500 studenten. Opvallend is dat mannelijke studenten uit Twente zich veel minder druk lijken te maken over hun studie. Onder vrouwen ligt de stress juist erg hoog ten opzichte van het landelijk gemiddelde.
A proof of Bertrand's postulate
Directory of Open Access Journals (Sweden)
Andrea Asperti
2012-01-01
Full Text Available We discuss the formalization, in the Matita Interactive Theorem Prover, of some results by Chebyshev concerning the distribution of prime numbers, subsuming, as a corollary, Bertrand's postulate.Even if Chebyshev's result has been later superseded by the stronger prime number theorem, his machinery, and in particular the two functions psi and theta still play a central role in the modern development of number theory. The proof makes use of most part of the machinery of elementary arithmetics, and in particular of properties of prime numbers, gcd, products and summations, providing a natural benchmark for assessing the actual development of the arithmetical knowledge base.
Lakatos and Hersh on Mathematical Proof
Directory of Open Access Journals (Sweden)
Hossein Bayat
2015-12-01
Full Text Available The concept of Mathematical Proof has been controversial for the past few decades. Different philosophers have offered different theories about the nature of Mathematical Proof, among which theories presented by Lakatos and Hersh have had significant similarities and differences with each other. It seems that a comparison and critical review of these two theories will lead to a better understanding of the concept of mathematical proof and will be a big step towards solving many related problems. Lakatos and Hersh argue that, firstly, “mathematical proof” has two different meanings, formal and informal; and, secondly, informal proofs are affected by human factors, such as individual decisions and collective agreements. I call these two thesis, respectively, “proof dualism” and “humanism”. But on the other hand, their theories have significant dissimilarities and are by no means equivalent. Lakatos is committed to linear proof dualism and methodological humanism, while Hersh’s theory involves some sort of parallel proof dualism and sociological humanism. According to linear proof dualism, the two main types of proofs are provided in order to achieve a common goal: incarnation of mathematical concepts and methods and truth. However, according to the parallel proof dualism, two main types of proofs are provided in order to achieve two different types of purposes: production of a valid sequence of signs (the goal of the formal proof and persuasion of the audience (the goal of the informal proof. Hersh’s humanism is informative and indicates pluralism; whereas, Lakatos’ version of humanism is normative and monistic.
Formal Proofs for Nonlinear Optimization
Directory of Open Access Journals (Sweden)
Victor Magron
2015-01-01
Full Text Available We present a formally verified global optimization framework. Given a semialgebraic or transcendental function f and a compact semialgebraic domain K, we use the nonlinear maxplus template approximation algorithm to provide a certified lower bound of f over K.This method allows to bound in a modular way some of the constituents of f by suprema of quadratic forms with a well chosen curvature. Thus, we reduce the initial goal to a hierarchy of semialgebraic optimization problems, solved by sums of squares relaxations. Our implementation tool interleaves semialgebraic approximations with sums of squares witnesses to form certificates. It is interfaced with Coq and thus benefits from the trusted arithmetic available inside the proof assistant. This feature is used to produce, from the certificates, both valid underestimators and lower bounds for each approximated constituent.The application range for such a tool is widespread; for instance Hales' proof of Kepler's conjecture yields thousands of multivariate transcendental inequalities. We illustrate the performance of our formal framework on some of these inequalities as well as on examples from the global optimization literature.
Fledderus, M.
2012-01-01
Twee op de vijf UT-studenten hebben last van ernstige studiestress, zo erg zelfs dat het ze in hun privéleven belemmert. Die cijfers komen overeen met het landelijk beeld van stress onder studenten. Samen met 14 andere universiteits- en hogeschoolbladen enquêteerde UT Nieuws bijna 5500 studenten.
Introduction to proof in abstract mathematics
Wohlgemuth, Andrew
2011-01-01
The primary purpose of this undergraduate text is to teach students to do mathematical proofs. It enables readers to recognize the elements that constitute an acceptable proof, and it develops their ability to do proofs of routine problems as well as those requiring creative insights. The self-contained treatment features many exercises, problems, and selected answers, including worked-out solutions. Starting with sets and rules of inference, this text covers functions, relations, operation, and the integers. Additional topics include proofs in analysis, cardinality, and groups. Six appendixe
Impact- and earthquake- proof roof structure
International Nuclear Information System (INIS)
Shohara, Ryoichi.
1990-01-01
Building roofs are constituted with roof slabs, an earthquake proof layer at the upper surface thereof and an impact proof layer made of iron-reinforced concrete disposed further thereover. Since the roofs constitute an earthquake proof structure loading building dampers on the upper surface of the slabs by the concrete layer, seismic inputs of earthquakes to the buildings can be moderated and the impact-proof layer is formed, to ensure the safety to external conditions such as earthquakes or falling accidents of airplane in important facilities such as reactor buildings. (T.M.)
International Nuclear Information System (INIS)
Maier, H.R.; Nink, H.; Krauth, A.
1977-01-01
A prediction of the reliability of structural components requires the definition of transfer data from the combination of materials data, design criteria and application conditions. The determination and transfer of strength data are one unit and therefore similar approximations are necessary. The influence of loading conditions, proof testing and analysing methods is explained with bending tests of rectangular specimens and burst tests of big tubes at room temperature. The drop in strength from 180 N/mm 2 to 50 N/mm 2 via a size factor of 10 5 is predicted and experimentally verified with the most simple statistical extension. The results have been applied to special problems of stress concentrations and give conclusions for test techniques and design fundamentals. (orig.) [de
Bistatic SAR: Proof of Concept.
Energy Technology Data Exchange (ETDEWEB)
Yocky, David A.; Doren, Neall E.; Bacon, Terry A.; Wahl, Daniel E.; Eichel, Paul H.; Jakowatz, Charles V,; Delaplain, Gilbert G.; Dubbert, Dale F.; Tise, Bertice L.; White, Kyle R.
2014-10-01
Typical synthetic aperture RADAR (SAR) imaging employs a co-located RADAR transmitter and receiver. Bistatic SAR imaging separates the transmitter and receiver locations. A bistatic SAR configuration allows for the transmitter and receiver(s) to be in a variety of geometric alignments. Sandia National Laboratories (SNL) / New Mexico proposed the deployment of a ground-based RADAR receiver. This RADAR receiver was coupled with the capability of digitizing and recording the signal collected. SNL proposed the possibility of creating an image of targets the illuminating SAR observes. This document describes the developed hardware, software, bistatic SAR configuration, and its deployment to test the concept of a ground-based bistatic SAR. In the proof-of-concept experiments herein, the RADAR transmitter will be a commercial SAR satellite and the RADAR receiver will be deployed at ground level, observing and capturing RADAR ground/targets illuminated by the satellite system.
Zazkis, Dov; Zazkis, Rina
2016-01-01
A significant body of research literature in mathematics education attends to mathematical proofs. However, scant research attends to proof comprehension, which is the focus of this study. We examine perspective secondary teachers' conceptions of what constitutes comprehension of a given proof and their ideas of how students' comprehension can be…
Proof Problems with Diagrams: An Opportunity for Experiencing Proofs and Refutations
Komatsu, Kotaro; Tsujiyama, Yosuke; Sakamaki, Aruta; Koike, Norio
2014-01-01
It has become gradually accepted that proof and proving are essential at all grades of mathematical learning. Among the various aspects of proof and proving, this study addresses proofs and refutations described by Lakatos, in particular a part of increasing content by deductive guessing, to introduce an authentic process into mathematics…
47 CFR 73.154 - AM directional antenna partial proof of performance measurements.
2010-10-01
... available to the FCC upon request. Maps showing new measurement points, i.e., points not measured in the...) Measurement points shall be selected from the points measured in latest full proof of performance provided..., the licensee shall measure directional field strength for comparison to either the directional or the...
Multiparty session types as coherence proofs
DEFF Research Database (Denmark)
Carbone, Marco; Montesi, Fabrizio; Schürmann, Carsten
2017-01-01
We propose a Curry–Howard correspondence between a language for programming multiparty sessions and a generalisation of Classical Linear Logic (CLL). In this framework, propositions correspond to the local behaviour of a participant in a multiparty session type, proofs to processes, and proof nor...
Verifying Process Algebra Proofs in Type Theory
Sellink, M.P.A.
In this paper we study automatic verification of proofs in process algebra. Formulas of process algebra are represented by types in typed λ-calculus. Inhabitants (terms) of these types represent proofs. The specific typed λ-calculus we use is the Calculus of Inductive Constructions as implemented
Other trigonometric proofs of Pythagoras theorem
Luzia, Nuno
2015-01-01
Only very recently a trigonometric proof of the Pythagoras theorem was given by Zimba \\cite{1}, many authors thought this was not possible. In this note we give other trigonometric proofs of Pythagoras theorem by establishing, geometrically, the half-angle formula $\\cos\\theta=1-2\\sin^2 \\frac{\\theta}{2}$.
Proof in Algebra: Reasoning beyond Examples
Otten, Samuel; Herbel-Eisenmann, Beth A.; Males, Lorraine M.
2010-01-01
The purpose of this article is to provide an image of what proof could look like in beginning algebra, a course that nearly every secondary school student encounters. The authors present an actual classroom vignette in which a rich opportunity for student reasoning arose. After analyzing the proof schemes at play, the authors provide a…
On Callan's proof of the BPHZ theorem
International Nuclear Information System (INIS)
Lesniewski, A.
1984-01-01
The author gives an elementary proof of the BPHZ theorem in the case of the Euclidean lambdaphi 4 theory. The method of proof relies on a detailed analysis of the skeleton structure of graphs and estimates based on the Callan-Symanzik equations. (Auth.)
Interval logic. Proof theory and theorem proving
DEFF Research Database (Denmark)
Rasmussen, Thomas Marthedal
2002-01-01
of a direction of an interval, and present a sound and complete Hilbert proof system for it. Because of its generality, SIL can conveniently act as a general formalism in which other interval logics can be encoded. We develop proof theory for SIL including both a sequent calculus system and a labelled natural...
Proof Mining in L1-Approximation
DEFF Research Database (Denmark)
Oliva, Paulo Borges; Kohlenbach, Ulrich
2001-01-01
In this paper, we present another case study in the general project of proof mining which means the logical analysis of prima facie non-effective proofs with the aim of extracting new computationally relevant data. We use techniques based on monotone functional interpretation developed...
Proof Mining in L1-Approximation
DEFF Research Database (Denmark)
Kohlenbach, Ulrich; Oliva, Paulo Borges
2003-01-01
n this paper, we present another case study in the general project of proof mining which means the logical analysis of prima facie non-effective proofs with the aim of extracting new computationally relevant data. We use techniques based on monotone functional interpretation developed in Kohlenbach...
Directory of Open Access Journals (Sweden)
Manuel Guillén-del Castillo
2011-01-01
Full Text Available ResumenEl ejercicio físico puede producir estrés oxidativo en el individuo lo que pueden condicionar el riesgo cardiovascular en niños y adolescentes. Este estudio pretende analizar el estrés oxidativo según la fuerza muscular isométrica de las extremidades superiores en la edad pediátrica. Se estudiaron 70 niños sanos con edades entre 10 y 14 años, y se analizaron en saliva los lipoperóxidos (LPO, el glutatión reducido (GSH, la ratio GSH/LPO y la catalasa, como marcadores de estrés oxidativo. La muestra se dividió en dos grupos según una condición física superior o inferior medida a través de dinamometría manual (TKK 5110; se diferenció la serie en sujetos prepuberales y puberales. Se encontraron niveles significativamente inferiores de GSH y GSH/LPO en el grupo de niños con fuerza superior, y en los puberales con la mismas características; estos resultados podrían indicar la existencia de un mayor estrés oxidativo en esta situación. En conclusión, los mayores niveles de fuerza músculo esquelética, medida a través de dinamometría manual, posiblemente pueden estar asociados a un mayor estrés oxidativo en niños púberes con condición física musculoesquelética superior.AbstractPhysical exercise can produce oxidative stress, this situation could contribute cardiovascular risk in children and adolescents. The following study tries to evaluate the oxidative stress produced according to the handgrip strength in infancy. 70 healthy male subjects, ages 10 to 14 years, were studied. In the saliva samples, lipoperoxides (LPO, reduced glutathione (GSH, glutathione/lipoperoxides ratio and catalase were analyzed as biomarkers of oxidative stress. Children were divided into two groups according to their handgrip strength (high or low measured by handgrip strength (TKK 5110. The groups were also divided into prepubertal and pubertal subjects. We found GSH’s significantly low levels and of GSH/LPO in pubertal group with high
Completing Einstein's Proof of E=mc2
Directory of Open Access Journals (Sweden)
Lo C. Y.
2006-10-01
Full Text Available It is shown that Einstein’s proof for E=mc2 is actually incomplete and therefore is not yet valid. A crucial step is his implicit assumption of treating the light as a bundle of massless particles. However, the energy-stress tensor of massless particles is incompatible with an electromagnetic energy-stress tensor. Thus, it is necessary to show that the total energy of a light ray includes also non-electromagnetic energy. It turns out, the existence of intrinsic difference between the photonic and the electromagnetic energy tensors is independent of the coupling of gravity. Nevertheless, their difference is the energy-stress tensor of the gravitational wave component that is accompanying the electromagnetic wave component. Concurrently, it is concluded that Einstein’s formula E=mc2 necessarily implies that the photons include non- electromagnetic energy and that the Einstein equation of 1915 must be rectified.
Chambers, David W
2008-01-01
We all experience stress as a regular, and sometimes damaging and sometimes useful, part of our daily lives. In our normal ups and downs, we have our share of exhaustion, despondency, and outrage--matched with their corresponding positive moods. But burnout and workaholism are different. They are chronic, dysfunctional, self-reinforcing, life-shortening habits. Dentists, nurses, teachers, ministers, social workers, and entertainers are especially susceptible to burnout; not because they are hard-working professionals (they tend to be), but because they are caring perfectionists who share control for the success of what they do with others and perform under the scrutiny of their colleagues (they tend to). Workaholics are also trapped in self-sealing cycles, but the elements are ever-receding visions of control and using constant activity as a barrier against facing reality. This essay explores the symptoms, mechanisms, causes, and successful coping strategies for burnout and workaholism. It also takes a look at the general stress response on the physiological level and at some of the damage American society inflicts on itself.
International Nuclear Information System (INIS)
Urabe, Yoshio
2017-01-01
The R and D of fatigue strength at multiaxial stress intensity is recognized to become extremely important in the future in terms of the elaboration of low-cycle fatigue evaluation of various structures including piping systems and reflection on those standards. This paper focuses on the evaluation method developed by the author, namely cumulative damage rule in consideration of multiaxial stress intensity, and explains the concept and the results of verification and evaluation. It also discusses the engineering problems of the current low cycle fatigue assessment technology that were clarified in the process of developing low-cycle fatigue assessment method based on multiaxial stress intensity. The conservative lifespan and somewhat more conservative actual lifetime of elbow piping can be estimated by the conventional 'revised universal slope method' and 'advanced revised universal slope method.' However, these are empirical rules, and the theoretical basis is not clear. From 'cumulative damage rule in consideration of multiaxial stress intensity,' the author calculated furthermore 'low cycle fatigue evaluation formula based on cumulative damage rule in consideration of multi-axial stress intensity,' and examined it. As a result, an evaluation formula that can reasonably assume the equivalent thermoplastic strain range could be obtained at half of the repeat count as targeted. Furthermore, at the stage where future high precision FEM analysis can be used, direct low-cycle fatigue life curve can be established. (A.O.)
Distributed analysis with PROOF in ATLAS collaboration
International Nuclear Information System (INIS)
Panitkin, S Y; Ernst, M; Ito, H; Maeno, T; Majewski, S; Rind, O; Tarrade, F; Wenaus, T; Ye, S; Benjamin, D; Montoya, G Carillo; Guan, W; Mellado, B; Xu, N; Cranmer, K; Shibata, A
2010-01-01
The Parallel ROOT Facility - PROOF is a distributed analysis system which allows to exploit inherent event level parallelism of high energy physics data. PROOF can be configured to work with centralized storage systems, but it is especially effective together with distributed local storage systems - like Xrootd, when data are distributed over computing nodes. It works efficiently on different types of hardware and scales well from a multi-core laptop to large computing farms. From that point of view it is well suited for both large central analysis facilities and Tier 3 type analysis farms. PROOF can be used in interactive or batch like regimes. The interactive regime allows the user to work with typically distributed data from the ROOT command prompt and get a real time feedback on analysis progress and intermediate results. We will discuss our experience with PROOF in the context of ATLAS Collaboration distributed analysis. In particular we will discuss PROOF performance in various analysis scenarios and in multi-user, multi-session environments. We will also describe PROOF integration with the ATLAS distributed data management system and prospects of running PROOF on geographically distributed analysis farms.
Distributed analysis with PROOF in ATLAS collaboration
Energy Technology Data Exchange (ETDEWEB)
Panitkin, S Y; Ernst, M; Ito, H; Maeno, T; Majewski, S; Rind, O; Tarrade, F; Wenaus, T; Ye, S [Brookhaven National Laboratory, Upton, NY 11973 (United States); Benjamin, D [Duke University, Durham, NC 27708 (United States); Montoya, G Carillo; Guan, W; Mellado, B; Xu, N [University of Wisconsin-Madison, Madison, WI 53706 (United States); Cranmer, K; Shibata, A [New York University, New York, NY 10003 (United States)
2010-04-01
The Parallel ROOT Facility - PROOF is a distributed analysis system which allows to exploit inherent event level parallelism of high energy physics data. PROOF can be configured to work with centralized storage systems, but it is especially effective together with distributed local storage systems - like Xrootd, when data are distributed over computing nodes. It works efficiently on different types of hardware and scales well from a multi-core laptop to large computing farms. From that point of view it is well suited for both large central analysis facilities and Tier 3 type analysis farms. PROOF can be used in interactive or batch like regimes. The interactive regime allows the user to work with typically distributed data from the ROOT command prompt and get a real time feedback on analysis progress and intermediate results. We will discuss our experience with PROOF in the context of ATLAS Collaboration distributed analysis. In particular we will discuss PROOF performance in various analysis scenarios and in multi-user, multi-session environments. We will also describe PROOF integration with the ATLAS distributed data management system and prospects of running PROOF on geographically distributed analysis farms.
Hybrid Logic and its Proof-Theory
Brauner, Torben
2011-01-01
This is the first book-length treatment of hybrid logic and its proof-theory. Hybrid logic is an extension of ordinary modal logic which allows explicit reference to individual points in a model (where the points represent times, possible worlds, states in a computer, or something else). This is useful for many applications, for example when reasoning about time one often wants to formulate a series of statements about what happens at specific times. There is little consensus about proof-theory for ordinary modal logic. Many modal-logical proof systems lack important properties and the relatio
International Nuclear Information System (INIS)
Khristov, G.P.; Kosov, B.D.
1982-01-01
The paper deals with analysis of results of experimental studies in creep of the austenitic OKh16n15m3b steel with various size of initial-structure grain under conditions of high-intensity reactor irradiation and control tests. It is suggested to consider the material initial structure effect on intensity of minimum creep rates both under ordinary and intrareactor conditions of loading by means of the function grain size effect on the equivalent stress. It is shown that the criterial expression previously suggested by the authors is invariant to the type of stressed and structural states and relative to intensity of minimal creep rates. It is established that the creep rate of the irradiated steel may be calculated from dependence for nonirradiated steel using as an argument a certain reduced equivalent stress which is a function of the acting stress and irradiation parameter
Singaravelu, J.; Sundaresan, S.; Nageswara Rao, B.
2013-04-01
This article presents a methodology for evaluation of the proof load factor (PLF) for clamp band system (CBS) made of M250 Maraging steel following fracture mechanics principles.CBS is most widely used as a structural element and as a separation system. Using Taguchi's design of experiments and the response surface method (RSM) the compact tension specimens were tested to establish an empirical relation for the failure load ( P max) in terms of the ultimate strength, width, thickness, and initial crack length. The test results of P max closely matched with the developed RSM empirical relation. Crack growth rates of the maraging steel in different environments were examined. Fracture strength (σf) of center surface cracks and through-crack tension specimens are evaluated utilizing the fracture toughness ( K IC). Stress induced in merman band at flight loading conditions is evaluated to estimate the higher load factor and PLF. Statistical safety factor and reliability assessments were made for the specified flaw sizes useful in the development of fracture control plan for CBS of launch vehicles.
Nuclear threshold effects and neutron strength function
International Nuclear Information System (INIS)
Hategan, Cornel; Comisel, Horia
2003-01-01
One proves that a Nuclear Threshold Effect is dependent, via Neutron Strength Function, on Spectroscopy of Ancestral Neutron Threshold State. The magnitude of the Nuclear Threshold Effect is proportional to the Neutron Strength Function. Evidence for relation of Nuclear Threshold Effects to Neutron Strength Functions is obtained from Isotopic Threshold Effect and Deuteron Stripping Threshold Anomaly. The empirical and computational analysis of the Isotopic Threshold Effect and of the Deuteron Stripping Threshold Anomaly demonstrate their close relationship to Neutron Strength Functions. It was established that the Nuclear Threshold Effects depend, in addition to genuine Nuclear Reaction Mechanisms, on Spectroscopy of (Ancestral) Neutron Threshold State. The magnitude of the effect is proportional to the Neutron Strength Function, in their dependence on mass number. This result constitutes also a proof that the origins of these threshold effects are Neutron Single Particle States at zero energy. (author)
Evaluating Google compute engine with PROOF
International Nuclear Information System (INIS)
Ganis, Gerardo; Panitkin, Sergey
2014-01-01
The advent of private and commercial cloud platforms has opened the question of evaluating the cost-effectiveness of such solution for computing in High Energy Physics . Google Compute Engine (GCE) is a IaaS product launched by Google as an experimental platform during 2012 and now open to the public market. In this contribution we present the results of a set of CPU-intensive and I/O-intensive tests we have run with PROOF on a GCE resources made available by Google for test purposes. We have run tests on large scale PROOF clusters (up to 1000 workers) to study the overall scalability of coordinated multi-process jobs. We have studied and compared the performance of ephemeral and persistent storage with PROOF-Lite on the single machines and of standard PROOF on the whole cluster. We will discuss our results in perspective, in particular with respect to the typical analysis needs of an LHC experiment.
Towards an Intelligent Tutor for Mathematical Proofs
Directory of Open Access Journals (Sweden)
Serge Autexier
2012-02-01
Full Text Available Computer-supported learning is an increasingly important form of study since it allows for independent learning and individualized instruction. In this paper, we discuss a novel approach to developing an intelligent tutoring system for teaching textbook-style mathematical proofs. We characterize the particularities of the domain and discuss common ITS design models. Our approach is motivated by phenomena found in a corpus of tutorial dialogs that were collected in a Wizard-of-Oz experiment. We show how an intelligent tutor for textbook-style mathematical proofs can be built on top of an adapted assertion-level proof assistant by reusing representations and proof search strategies originally developed for automated and interactive theorem proving. The resulting prototype was successfully evaluated on a corpus of tutorial dialogs and yields good results.
Parallel interactive data analysis with PROOF
International Nuclear Information System (INIS)
Ballintijn, Maarten; Biskup, Marek; Brun, Rene; Canal, Philippe; Feichtinger, Derek; Ganis, Gerardo; Kickinger, Guenter; Peters, Andreas; Rademakers, Fons
2006-01-01
The Parallel ROOT Facility, PROOF, enables the analysis of much larger data sets on a shorter time scale. It exploits the inherent parallelism in data of uncorrelated events via a multi-tier architecture that optimizes I/O and CPU utilization in heterogeneous clusters with distributed storage. The system provides transparent and interactive access to gigabytes today. Being part of the ROOT framework PROOF inherits the benefits of a performant object storage system and a wealth of statistical and visualization tools. This paper describes the data analysis model of ROOT and the latest developments on closer integration of PROOF into that model and the ROOT user environment, e.g. support for PROOF-based browsing of trees stored remotely, and the popular TTree::Draw() interface. We also outline the ongoing developments aimed to improve the flexibility and user-friendliness of the system
Proof of payment for all reimbursement claims
HR Department
2006-01-01
Members of the personnel are kindly requested to note that only documents proving that a payment has been made are accepted as proof of payment for any claims for reimbursement, including specifically the reimbursement of education fees. In particular, the following will be accepted as proof of payment: bank or post office bank statements indicating the name of the institution to which the payment was made; photocopies of cheques made out to the institution to which the payments were made together with bank statements showing the numbers of the relevant cheques; proof of payment in the form of discharged payment slips; invoices with acknowledgement of settlement, receipts, bank statements detailing operations crediting another account or similar documents. As a result, the following documents in particular will no longer be accepted as proof of payment: photocopies of cheques that are not submitted together with bank or post office bank statements showing the numbers of the relevant cheques; details of ...
Problems and proofs in numbers and algebra
Millman, Richard S; Kahn, Eric Brendan
2015-01-01
Designed to facilitate the transition from undergraduate calculus and differential equations to learning about proofs, this book helps students develop the rigorous mathematical reasoning needed for advanced courses in analysis, abstract algebra, and more. Students will focus on both how to prove theorems and solve problem sets in-depth; that is, where multiple steps are needed to prove or solve. This proof technique is developed by examining two specific content themes and their applications in-depth: number theory and algebra. This choice of content themes enables students to develop an understanding of proof technique in the context of topics with which they are already familiar, as well as reinforcing natural and conceptual understandings of mathematical methods and styles. The key to the text is its interesting and intriguing problems, exercises, theorems, and proofs, showing how students will transition from the usual, more routine calculus to abstraction while also learning how to “prove” or “sol...
2010-07-01
... SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.233 Proof. In addition to the... must be established. (d) Whether alternative employment or business was available and undertaken and...
A short proof of increased parabolic regularity
Directory of Open Access Journals (Sweden)
Stephen Pankavich
2015-08-01
Full Text Available We present a short proof of the increased regularity obtained by solutions to uniformly parabolic partial differential equations. Though this setting is fairly introductory, our new method of proof, which uses a priori estimates and an inductive method, can be extended to prove analogous results for problems with time-dependent coefficients, advection-diffusion or reaction diffusion equations, and nonlinear PDEs even when other tools, such as semigroup methods or the use of explicit fundamental solutions, are unavailable.
Symbolic logic syntax, semantics, and proof
Agler, David
2012-01-01
Brimming with visual examples of concepts, derivation rules, and proof strategies, this introductory text is ideal for students with no previous experience in logic. Students will learn translation both from formal language into English and from English into formal language; how to use truth trees and truth tables to test propositions for logical properties; and how to construct and strategically use derivation rules in proofs.
CIRCULATING MOVING BED COMBUSTION PROOF OF CONCEPT
Energy Technology Data Exchange (ETDEWEB)
Jukkola, Glen
2010-06-30
Circulating Moving Bed (CMB) combustion technology has its roots in traditional circulating fluidized bed technology and involves a novel method of solid fuel combustion and heat transfer. CMB technology represents a step change in improved performance and cost relative to conventional PC and FBC boilers. The CMB heat exchanger preheats the energy cycle working fluid, steam or air, to the high temperature levels required in systems for advanced power generation. Unique features of the CMB are the reduction of the heat transfer surfaces by about 60% as a result of the enhanced heat transfer rates, flexibility of operation, and about 30% lower cost over existing technology. The CMB Phase I project ran from July 2001 through March 2003. Its objective was to continue development of the CMB technology with a series of proof of concept tests. The tests were conducted at a scale that provided design data for scale up to a demonstration plant. These objectives were met by conducting a series of experiments in ALSTOM Power’s Multi-use Test Facility (MTF). The MTF was modified to operate under CMB conditions of commercial interest. The objective of the tests were to evaluate gas-to-solids heat transfer in the upper furnace, assess agglomeration in the high temperature CMB bubbling bed, and evaluate solids-to-tube heat transfer in the moving bed heat exchanger. The Phase I program results showed that there are still some significant technical uncertainties that needed to be resolved before the technology can be confidently scaled up for a successful demonstration plant design. Work remained in three primary areas: • scale up of gas to solid heat transfer • high temperature finned surface design • the overall requirements of mechanical and process design. The CMB Phase II workscope built upon the results of Phase I and specifically addressed the remaining technical uncertainties. It included a scaled MTF heat transfer test to provide the necessary data to scale up gas
International Nuclear Information System (INIS)
Kamaya, Masayuki; Hojo, Tomohiro; Mochizuki, Masahito
2015-01-01
Load carrying capacity of austenitic stainless steel component is increased due to hardening caused by neutron irradiation if no crack is included in the component. On the other hand, if a crack is initiated in the reactor components, the hardening may decrease the load carrying capacity due to reduction in fracture toughness. In this paper, in order to develop a failure assessment procedure of irradiated cracked components, characteristics of change in failure strength of stainless steels due to cold working were investigated. It was experimentally shown that the proof and tensile strengths were increased by the cold working, whereas the fracture toughness was decreased. The fracture strengths of a cylinder with a circumferential surface crack were analyzed using the obtained material properties. Although the cold working altered the failure mode from plastic collapse to the unsteady ductile crack growth, it did not reduce failure strengths even if 50% cold working was applied. The increase in failure strength was caused not only by increase in flow stress but also by reduction in J-integral value, which was brought by the change in stress-strain curve. It was shown that the failure strength of the hardened stainless steel components could be derived by the two-parameter method, in which the change in material properties could be reasonably considered. (author)
A calculation method of cracking moment for the high strength ...
Indian Academy of Sciences (India)
mal stress and crack width for the tensional behaviour of concrete and has been proposed by ... stresses. To calculate concrete stress in a cross section of high strength concrete beams, failure strain is ..... American Concrete. Institute, Detroit.
Kimura, N.; Iwashita, N.; Masuda, T.
2009-04-01
1. Introduction Previous studies have compiled yield-strength profiles of continental lithosphere based on the results of laboratory measurements and numerical calculations; however, yield-strength values remain poorly constrained, especially at depths below the brittle-plastic transition zone. Recent studies by the authors have refined the microboudin technique for estimating palaeostress magnitude in the deep crust (> 10 km depth). This technique has the potential to provide important information on stress levels in the deep continental crust, an environment to which available in situ stress measurements and palaeopiezometric methods cannot be applied. In applying the microboudinage technique, obtaining an estimate of the palaeostress magnitude requires knowledge of the fracture strength of columnar accessory minerals (e.g., tourmaline, amphibole, and epidote) that are subjected to brittle fracturing during plastic deformation of the surrounding matrix minerals. The absolute magnitude of fracture strength is known to show a marked reduction in the case of fatigue fracture. Fatigue fracture falls into two categories: static fatigue and cyclic fatigue. In the field of experimental rock deformation, stress corrosion by water molecules (static fatigue) is commonly invoked as the mechanism of fatigue fracture; however, evidence of both static and cyclic fatigue has been reported from studies of natural geological samples. The present study focused on the fatigue properties of columnar accessory minerals at high temperatures, with the aim of improving the accuracy of estimates of natural palaeostress magnitude at depth in the crust. 2. Constant stress-rate test A constant stress-rate test was performed to determine the influence of static fatigue on the strength of columnar accessory minerals. The test was conducted under three-point bending with a span distance of 10 mm. Temperature conditions and the crosshead speed were set in the ranges of ambient to 600°C, and 0
Howe, Lauren C; Krosnick, Jon A
2017-01-03
Attitude strength has been the focus of a huge volume of research in psychology and related sciences for decades. The insights offered by this literature have tremendous value for understanding attitude functioning and structure and for the effective application of the attitude concept in applied settings. This is the first Annual Review of Psychology article on the topic, and it offers a review of theory and evidence regarding one of the most researched strength-related attitude features: attitude importance. Personal importance is attached to an attitude when the attitude is perceived to be relevant to self-interest, social identification with reference groups or reference individuals, and values. Attaching personal importance to an attitude causes crystallizing of attitudes (via enhanced resistance to change), effortful gathering and processing of relevant information, accumulation of a large store of well-organized relevant information in long-term memory, enhanced attitude extremity and accessibility, enhanced attitude impact on the regulation of interpersonal attraction, energizing of emotional reactions, and enhanced impact of attitudes on behavioral intentions and action. Thus, important attitudes are real and consequential psychological forces, and their study offers opportunities for addressing behavioral change.
46 CFR 201.144 - Offer of proof.
2010-10-01
... 46 Shipping 8 2010-10-01 2010-10-01 false Offer of proof. 201.144 Section 201.144 Shipping... PROCEDURE Evidence (Rule 14) § 201.144 Offer of proof. An offer of proof made in connection with an... accompany the record as the offer of proof. ...
45 CFR 81.85 - Offer of proof.
2010-10-01
... 45 Public Welfare 1 2010-10-01 2010-10-01 false Offer of proof. 81.85 Section 81.85 Public Welfare... 80 OF THIS TITLE Hearing Procedures § 81.85 Offer of proof. An offer of proof made in connection with... identification and shall accompany the record as the offer of proof. ...
38 CFR 18b.64 - Offer of proof.
2010-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Offer of proof. 18b.64... Procedures § 18b.64 Offer of proof. An offer of proof made in connection with an objection taken to any... record as the offer of proof. ...
Vibration-proof FBR type reactor
International Nuclear Information System (INIS)
Kawamura, Yutaka.
1992-01-01
In a reactor container in an FBR type reactor, an outer building and upper and lower portions of a reactor container are connected by a load transmission device made of a laminated material of rubber and steel plates. Each of the reactor container and the outer building is disposed on a lower raft disposed on a rock by way of a vibration-proof device made of a laminated material of rubber and steel plates. Vibration-proof elements for providing vertical eigen frequency of the vibration-proof system comprising the reactor building and the vibration-proof device within a range of 3Hz to 5Hz are used. That is, the peak of designed acceleration for response spectrum in the horizontal direction of the reactor structural portions is shifted to side of shorter period from the main frequency region of the reactor structure. Alternatively, rigidity of the vibration-proof elements is decreased to shift the peak to the side of long period from the main frequency region. Designed seismic force can be greatly reduced both horizontally and vertically, to reduce the wall thickness of the structural members, improve the plant economy and to ensure the safety against earthquakes. (N.H.)
Mobile Data Collection Applications: A Proof of Concept
International Nuclear Information System (INIS)
Chang, J
2006-01-01
This project's goal is to provide a proof of concept for mobile data collection applications, and identify the best ways such applications could be implemented and used. Such an application should decrease the time and resources users now need to devote to redundant data processes, and provide an easy of locating and retrieving data at a later time. The two types of available mobile devices, Personal Digital Assistants and Tablet Personal Computers, each have their particular strengths that suggest themselves for certain types of applications. As such, parallel data collection applications have been developed, with a common web application for uploading information to the database. While these aspects have been developed and proven, it still remains to refine these applications, develop the tables to hold their data, and field-test with users for their feedback
A Critique of a Phenomenological Fiber Breakage Model for Stress Rupture of Composite Materials
Reeder, James R.
2010-01-01
Stress rupture is not a critical failure mode for most composite structures, but there are a few applications where it can be critical. One application where stress rupture can be a critical design issue is in Composite Overwrapped Pressure Vessels (COPV's), where the composite material is highly and uniformly loaded for long periods of time and where very high reliability is required. COPV's are normally required to be proof loaded before being put into service to insure strength, but it is feared that the proof load may cause damage that reduces the stress rupture reliability. Recently, a fiber breakage model was proposed specifically to estimate a reduced reliability due to proof loading. The fiber breakage model attempts to model physics believed to occur at the microscopic scale, but validation of the model has not occurred. In this paper, the fiber breakage model is re-derived while highlighting assumptions that were made during the derivation. Some of the assumptions are examined to assess their effect on the final predicted reliability.
Tomita, Yoshiyuki; Okabayashi, Kunio
1985-01-01
In the previous papers, a new heat treatment for improving the lower temperature mechanical propertise of the ultrahigh strength low alloy steels was suggested by the authors which produces a mixed structure of 25 vol pct lower bainite and 75 vol pct martensite through isothermal transformation at 593 K for a short time followed by water quenching (after austenitization at 1133 K). In this paper, two commercial Japanese ultrahigh strength steels, 0.40 pct C-Ni-Cr-Mo (AISI 4340 type) and 0.40 pct C-Cr-Mo (AISI 4140 type), have been studied to determine the effect of the modified heat treatment, coupled above new heat treatment with γ ⇆ α' repctitive heat treatment, on the mechanical properties from ambient temperature (287 K) to 123 K. The results obtained for various test temperatures have been compared with those for the new heat treatment reported previously and the conventional 1133 K direct water quenching treatment. The incorporation of intermediate four cyclic γ ⇆ α' repctitive heat treatment steps (after the initial austenitization at 1133 K and oil quenching) into the new heat treatment reported previously, as compared with the conventional 1133 K direct water quenching treatment, significantly improved 0.2 pct proof stress as well as notch toughness of the 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel at similar fracture ductility levels from 287 to 123 K. Also, this heat treatment, as compared with the conventional 1133 K direct water quenching treatment, significantly improved both 0.2 pct proof stress and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel with increased fracture ductility at 203 K and above. The microstructure consists of mixed areas of ultrafine grained martensite, within which is the refined blocky, highly dislocated structure, and the second phase lower bainite (about 15 vol pct), which appears in acicular form and partitions prior austenite grains. This newly developed heat treatment makes it possible to modify
Proof testing of CANDU concrete containment structures
International Nuclear Information System (INIS)
Pandey, M.D.
1996-05-01
Prior to commissioning of a CANDU reactor, a proof pressure test is required to demonstrate the structural integrity of the containment envelope. The test pressure specified by AECB Regulatory Document R-7 (1991) was selected without a rigorous consideration of uncertainties associated with estimates of accident pressure and conatinment resistance. This study was undertaken to develop a reliability-based philosophy for defining proof testing requirements that are consistent with the current limit states design code for concrete containments (CSA N287.3).It was shown that the upodated probability of failure after a successful test is always less than the original estimate
International Nuclear Information System (INIS)
Sakimoto, P.J.
1985-01-01
Quasi-Stellar Objects (QSOs) are apparently the excessively bright nuclei of distant galaxies. They are thought to be powered by accretion disks surrounding supermassive black holes: however, proof of this presumption is hampered by major uncertainties in the viscous stress necessary for accretion to occur. Models generally assume an and hoc stress law which scales the stress with the total pressure. Near the black hole, radiation pressure dominates gas pressure; scaling the stress with the radiation pressure results in disk models that are thermally unstable and optically thin. This dissertation shows that a radiation pressure scaling for the stress is not possible if the viscosity is due to turbulent magnetic Maxwell stresses. The argument is one of internal self-consistency. First, four model accretion disks that bound the reasonably expected ranges of viscous stress scalings and vertical structures are constructed. Magnetic flux tubes of various initial field strengths are then placed within these models, nd their buoyancy is modeled numerically. In disks using the radiation pressure stress law scaling, low opacities allow rapid heat flow into the flux tubes: the tubes are extremely buoyant, and magnetic fields strong enough to provide the required stress cannot be retained. If an alternative gas pressure scaling for the stress is assumed, then the disks are optically thick; flux tubes have corresponding lower buoyancy, and magnetic fields strong enough to provide the stress can be retained for dynamically significant time periods
International Nuclear Information System (INIS)
Hosoi, Y.; Okazaki, Y.; Wade, N.; Miyahara, K.
1990-01-01
High Mn-Cr-Fe base alloys are candidates for the first wall material of fusion reactors because of rapid decay of radioactivity of the alloys after neutron irradiation compared with that of Ni-Cr-Fe base alloys. Their high temperature properties, however, are not clearly understood at present. In this paper, a study has been made of the effects of Mn, C and N content on the high-temperature tensile strength and creep properties of a 12% CR-Fe base alloy. Mn tends to decrease tensile strength and proof stress at intermediate temperatures. At higher temperatures in the austenite range, however, tensile properties scarcely depend on Mn content. C and N additions improve the tensile properties markedly. The combined addition of 0.2%C and 0.2%N to a 12%Cr-15%Mn-Fe base alloy makes the strength at 873K as high as that of a modified type 316 stainless steel. Combined alloying with C and N also improves the creep strength. Cold working is very useful in increasing the creep strength because of the finely dispersed precipitates in the matrix during creep. From these results, Fe-12%Cr-15%Mn-15%Mn-0.2%c-0.2%N is recommended as one of the most suitable alloys in this system for high temperature usage. (author)
Strength evaluation code STEP for brittle materials
International Nuclear Information System (INIS)
Ishihara, Masahiro; Futakawa, Masatoshi.
1997-12-01
In a structural design using brittle materials such as graphite and/or ceramics it is necessary to evaluate the strength of component under complex stress condition. The strength of ceramic materials is said to be influenced by the stress distribution. However, in the structural design criteria simplified stress limits had been adopted without taking account of the strength change with the stress distribution. It is, therefore, important to evaluate the strength of component on the basis of the fracture model for brittle material. Consequently, the strength evaluation program, STEP, on a brittle fracture of ceramic materials based on the competing risk theory had been developed. Two different brittle fracture modes, a surface layer fracture mode dominated by surface flaws and an internal fracture mode by internal flaws, are treated in the STEP code in order to evaluate the strength of brittle fracture. The STEP code uses stress calculation results including complex shape of structures analyzed by the generalized FEM stress analysis code, ABAQUS, so as to be possible to evaluate the strength of brittle fracture for the structures having complicate shapes. This code is, therefore, useful to evaluate the structural integrity of arbitrary shapes of components such as core graphite components in the HTTR, heat exchanger components made of ceramics materials etc. This paper describes the basic equations applying to the STEP code, code system with a combination of the STEP and the ABAQUS codes and the result of the verification analysis. (author)
Cooke, Matthew B; Nix, Carrie M; Greenwood, Lori D; Greenwood, Mike C
2018-03-01
Cooke, MB, Nix, C, Greenwood, L, and Greenwood, M. No Differences Between Alter G-Trainer and Active and Passive Recovery Strategies on Isokinetic Strength, Systemic Oxidative Stress and Perceived Muscle Soreness After Exercise-Induced Muscle Damage. J Strength Cond Res 32(3): 736-747, 2018-The incidence of muscle injuries is prevalent in elite sport athletes and weekend warriors and strategies that safely and effectively hasten recovery are highly desirable. The purpose of this study was to examine the differences between 3 recovery methods after eliciting muscle damage in recreationally active men relative to maximal isokinetic contractions, perceived muscle soreness, and psychological mood states. Twenty-five recreationally active men (22.15 ± 3.53 years, 75.75 ± 11.91 kg, 180.52 ± 7.3 cm) were randomly matched by V[Combining Dot Above]O2 peak (53.86 ± 6.65 ml·kg·min) and assigned to one of 3 recovery methods: anti-gravity treadmill (G-Trainer) (N = 8), conventional treadmill (N = 8) or static stretching (N = 9). Recovery methods were performed 30 minutes, 24, 48, and 72 hours after a 45-minute downhill run. Following eccentrically biased running, no significant differences were noted in isokinetic knee flexion and extension peak torque, systemic markers of muscle damage, oxidative stress and lipid peroxidation such as serum creatine kinase (CK), superoxide dismutase (SOD), and malondialdehyde (MDA), respectively, and subjective ratings of perceived muscle soreness between recovery methods. The G-Trainer group did however display a higher mood state as indicated by the Profile of Mood State global scores at 24 hours postexercise when compared to the conventional treadmill recovery group (p = 0.035). The improved mood state after the use of the anti-gravity treadmill may provide clinical relevance to other populations.
Skorobogatykh, V. N.; Danyushevskiy, I. A.; Schenkova, I. A.; Prudnikov, D. A.
2015-04-01
Currently, grade X10CrMoVNb9-1 (T91, P91) and 10Kh9MFB (10Kh9MFB-Sh) chromium steels are widely applied in equipment manufacturing for thermal power plants in Russia and abroad. Compilation and comparison of tensile, impact, and long-term strength tests results accumulated for many years of investigations of foreign grade X10CrMoVNb9-1, T91, P91, and domestic grade 10Kh9MFB (10Kh9MFB-Sh) steels is carried out. The property identity of metals investigated is established. High strength and plastic properties of steels, from which pipes and other products are made, for operation under creep conditions are confirmed. Design characteristics of long-term strength on the basis of tests with more than one million of hour-samples are determined ( and at temperatures of 500-650°C). The table of recommended allowable stresses for grade 10Kh9MFB, 10Kh9MFB-SH, X10CrMoVNb9-1, T91, and P91 steels is developed. The long-time properties of pipe welded joints of grade 10Kh9MFB+10Kh9MFB, 10Kh9MFB-Sh+10Kh9MFB-Sh, X10CrMoVNb9-1+X10CrMoVNb9-1, P91+P91, T91+T91, 10Kh9MFB (10Kh9MFB-Sh)+X10CrMoVNb9-1(T/P91) steels is researched. The welded joint reduction factor is experimentally determined.
Garber, E. A.; Yagudin, I. V.; Ermilov, V. V.; Traino, A. I.
2009-10-01
The reliability of the methods of determining the friction coefficient is analyzed, since the friction stresses in the deformation zone during cold rolling significantly affect the quality of cold-rolled sheets and the energy consumption. The well-known experimental data and empirical dependences are shown to contradict each other, and the statistical assurance of these dependences is absent. A database on the interrelated technological and energy-force parameters of a five-stand cold-rolling mill, which includes a wide range of steel grades and strip sizes and shapes, is analyzed. Regression analysis is used to obtain a statistically reliable regression dependence of the friction coefficient in the deformation zone on the most significant technological parameters. The application of this dependence decreases the error of energy-force calculations by more than two times.
Proof systems for Moss’ coalgebraic logic
Bílková, M.; Palmigiano, A.; Venema, Y.
2014-01-01
We study Gentzen-style proof theory of the finitary version of the coalgebraic logic introduced by L. Moss. The logic captures the behaviour of coalgebras for a large class of set functors. The syntax of the logic, defined uniformly with respect to a finitary coalgebraic type functor T , uses a
Data-oriented scheduling for PROOF
International Nuclear Information System (INIS)
Xu Neng; Guan Wen; Wu Sau Lan; Ganis, Gerardo
2011-01-01
The Parallel ROOT Facility - PROOF - is a distributed analysis system optimized for I/O intensive analysis tasks of HEP data. With LHC entering the analysis phase, PROOF has become a natural ingredient for computing farms at Tier3 level. These analysis facilities will typically be used by a few tenths of users, and can also be federated into a sort of analysis cloud corresponding to the Virtual Organization of the experiment. Proper scheduling is required to guarantee fair resource usage, to enforce priority policies and to optimize the throughput. In this paper we discuss an advanced priority system that we are developing for PROOF. The system has been designed to automatically adapt to unknown length of the tasks, to take into account the data location and availability (including distribution across geographically separated sites), and the {group, user} default priorities. In this system, every element - user, group, dataset, job slot and storage - gets its priority and those priorities are dynamically linked with each other. In order to tune the interplay between the various components, we have designed and started implementing a simulation application that can model various type and size of PROOF clusters. In this application a monitoring package records all the changes of them so that we can easily understand and tune the performance. We will discuss the status of our simulation and show examples of the results we are expecting from it.
2010-07-01
... FINANCIAL RESPONSIBILITY AND COMPENSATION OIL SPILL LIABILITY TRUST FUND; CLAIMS PROCEDURES; DESIGNATION OF SOURCE; AND ADVERTISEMENT Procedures for Particular Claims § 136.215 Proof. (a) In addition to the... each claim for economic loss resulting from destruction of real or personal property, the claimant must...
Teaching Syllogistics Through Gamification and Interactive Proofs
DEFF Research Database (Denmark)
Øhrstrøm, Peter; Sandborg-Petersen, Ulrik; Thorvaldsen, Steinar
2015-01-01
teaching through the use of interactive systems and also to do learning analytics based on the log-data from the use of the systems. The aim of the present paper is to investigate whether the use of gamification and an interactive proof system formulated in terms of controlled natural language can...
Czech Academy of Sciences Publication Activity Database
Peregrin, Jaroslav
-, č. 82 (2007), s. 1-10 E-ISSN 1742-6596 R&D Projects: GA ČR(CZ) GA401/04/0117 Institutional research plan: CEZ:AV0Z90090514 Keywords : Gödel * incompleteness of arithmetic * proof vs. truth Subject RIV: AA - Philosophy ; Religion http://www.iop.org/EJ/ toc /1742-6596/82/1
A Foundational Proof Framework for Cryptography
2015-05-01
uniformly-distributed natural numbers in [0, ) is shown in Listing 7. RndNat_h is a helper function that samples a natural number with the appro...expect that a skilled Coq developer could complete such a proof in a matter of days (though he may require the help of a cryptographer to develop the
A Short Proof of Klee's Theorem
Zanazzi, John J.
2013-01-01
In 1959, Klee proved that a convex body $K$ is a polyhedron if and only if all of its projections are polygons. In this paper, a new proof of this theorem is given for convex bodies in $\\mathbb{R}^3$.
Strategy-Proof Assignment Of Multiple Resources
DEFF Research Database (Denmark)
Erlanson, Albin; Szwagrzak, Karol
2015-01-01
We examine the strategy-proof allocation of multiple resources; an application is the assignment of packages of tasks, workloads, and compensations among the members of an organization. In the domain of multidimensional single-peaked preferences, we find that any allocation mechanism obtained by ...
Proof complexity of intuitionistic implicational formulas
Czech Academy of Sciences Publication Activity Database
Jeřábek, Emil
2017-01-01
Roč. 168, č. 1 (2017), s. 150-190 ISSN 0168-0072 EU Projects: European Commission(XE) 339691 - FEALORA Institutional support: RVO:67985840 Keywords : proof complexity * intuitionistic logic * implicational fragment Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.647, year: 2016 http://www.sciencedirect.com/science/article/pii/S0168007216301154
Complexity of Propositional Proofs Under a Promise
Czech Academy of Sciences Publication Activity Database
Dershowitz, N.; Tzameret, Iddo
2010-01-01
Roč. 11, č. 3 (2010), s. 1-29 ISSN 1529-3785 Institutional research plan: CEZ:AV0Z10190503 Keywords : theory * promise problems * propositional proof complexity * random 3CNF * resolution Subject RIV: BA - General Mathematics Impact factor: 1.391, year: 2010 http://dl.acm.org/ citation .cfm?doid=1740582.1740586
Complexity of Propositional Proofs Under a Promise
Czech Academy of Sciences Publication Activity Database
Dershowitz, N.; Tzameret, Iddo
2010-01-01
Roč. 11, č. 3 (2010), s. 1-29 ISSN 1529-3785 Institutional research plan: CEZ:AV0Z10190503 Keywords : theory * promise problems * propositional proof complexity * random 3CNF * resolution Subject RIV: BA - General Mathematics Impact factor: 1.391, year: 2010 http://dl.acm.org/citation.cfm?doid=1740582.1740586
Proof of Nishida's Conjecture on Anharmonic Lattices
Rink, Bob
2006-02-01
We prove Nishida's 1971 conjecture stating that almost all low-energetic motions of the anharmonic Fermi-Pasta-Ulam lattice with fixed endpoints are quasi-periodic. The proof is based on the formal computations of Nishida, the KAM theorem, discrete symmetry considerations and an algebraic trick that considerably simplifies earlier results.
Decorated proofs for computational effects: States
Directory of Open Access Journals (Sweden)
Jean-Guillaume Dumas
2012-08-01
Full Text Available The syntax of an imperative language does not mention explicitly the state, while its denotational semantics has to mention it. In this paper we show that the equational proofs about an imperative language may hide the state, in the same way as the syntax does.
Short proofs for the determinant identities
Czech Academy of Sciences Publication Activity Database
Hrubeš, Pavel; Tzameret, I.
2015-01-01
Roč. 44, č. 2 (2015), s. 340-383 ISSN 0097-5397 EU Projects: European Commission(XE) 339691 - FEALORA Program:FP7 Institutional support: RVO:67985840 Keywords : proof complexity * arithmetic circuits Subject RIV: BA - General Mathematics Impact factor: 0.841, year: 2015 http://epubs.siam.org/doi/abs/10.1137/130917788
Computer-Assisted Discovery and Proof
Energy Technology Data Exchange (ETDEWEB)
Bailey, David H.; Borwein, Jonathan M.
2007-12-10
With the advent of powerful, widely-available mathematical software, combined with ever-faster computer hardware, we are approaching a day when both the discovery and proof of mathematical facts can be done in a computer-assisted manner. his article presents several specific examples of this new paradigm in action.
Proofs of certain properties of irrational roots
Belbas, S. A.
2009-01-01
We give two elementary proofs, at a level understandable by students with only pre-calculus knowledge of Algebra, of the well known fact that an irreducible irrational n-th root of a positive rational number cannot be solution of a polynomial of degree less than n with rational coefficients. We also state and prove a few simple consequences.
Hash3: Proofs, Analysis and Implementation
DEFF Research Database (Denmark)
Gauravaram, Praveen
2009-01-01
This report outlines the talks presented at the winter school on Hash3: Proofs, Analysis, and Implementation, ECRYPT II Event on Hash Functions. In general, speakers may not write everything what they talk on the slides. So, this report also outlines such findings following the understanding of t...
Rock strength under explosive loading
International Nuclear Information System (INIS)
Rimer, N.; Proffer, W.
1993-01-01
This presentation emphasizes the importance of a detailed description of the nonlinear deviatoric (strength) response of the surrounding rock in the numerical simulation of underground nuclear explosion phenomenology to the late times needed for test ban monitoring applications. We will show how numerical simulations which match ground motion measurements in volcanic tuffs and in granite use the strength values obtained from laboratory measurements on small core samples of these rocks but also require much lower strength values after the ground motion has interacted with the rock. The underlying physical mechanisms for the implied strength reduction are not yet well understood, and in fact may depend on the particular rock type. However, constitutive models for shock damage and/or effective stress have been used successfully at S-Cubed in both the Geophysics Program (primarily for DARPA) and the Containment Support Program (for DNA) to simulate late time ground motions measured at NTS in many different rock types
Imaging Shear Strength Along Subduction Faults
Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Hardebeck, Jeanne L.
2017-11-01
Subduction faults accumulate stress during long periods of time and release this stress suddenly, during earthquakes, when it reaches a threshold. This threshold, the shear strength, controls the occurrence and magnitude of earthquakes. We consider a 3-D model to derive an analytical expression for how the shear strength depends on the fault geometry, the convergence obliquity, frictional properties, and the stress field orientation. We then use estimates of these different parameters in Japan to infer the distribution of shear strength along a subduction fault. We show that the 2011 Mw9.0 Tohoku earthquake ruptured a fault portion characterized by unusually small variations in static shear strength. This observation is consistent with the hypothesis that large earthquakes preferentially rupture regions with relatively homogeneous shear strength. With increasing constraints on the different parameters at play, our approach could, in the future, help identify favorable locations for large earthquakes.
Imaging shear strength along subduction faults
Bletery, Quentin; Thomas, Amanda M.; Rempel, Alan W.; Hardebeck, Jeanne L.
2017-01-01
Subduction faults accumulate stress during long periods of time and release this stress suddenly, during earthquakes, when it reaches a threshold. This threshold, the shear strength, controls the occurrence and magnitude of earthquakes. We consider a 3-D model to derive an analytical expression for how the shear strength depends on the fault geometry, the convergence obliquity, frictional properties, and the stress field orientation. We then use estimates of these different parameters in Japan to infer the distribution of shear strength along a subduction fault. We show that the 2011 Mw9.0 Tohoku earthquake ruptured a fault portion characterized by unusually small variations in static shear strength. This observation is consistent with the hypothesis that large earthquakes preferentially rupture regions with relatively homogeneous shear strength. With increasing constraints on the different parameters at play, our approach could, in the future, help identify favorable locations for large earthquakes.
Pluijm, van der R.; Vermeltfoort, A.Th.
1992-01-01
Bond strength is not a well defined property of masonry. Normally three types of bond strength can be distinguished: - tensile bond strength, - shear (and torsional) bond strength, - flexural bond strength. In this contribution the behaviour and strength of masonry in deformation controlled uniaxial
A Numerical Proof of Concept for Thermal Flow Control
Directory of Open Access Journals (Sweden)
V. Dragan
2017-02-01
Full Text Available In this paper computational fluid dynamics is used to provide a proof of concept for controlled flow separation using thermal wall interactions with the velocity boundary layer. A 3D case study is presented, using a transition modeling Shear Stress Transport turbulence model. The highly loaded single slot flap airfoil was chosen to be representative for a light aircraft and the flow conditions were modeled after a typical landing speed. In the baseline case, adiabatic walls were considered while in the separation control case, the top surface of the flaps was heated to 500 K. This heating lead to flow separation on the flaps and a significant alteration of the flow pattern across all the elements of the wing. The findings indicate that this control method has potential, with implications in both aeronautical as well as sports and civil engineering applications.
Effect of tensile overloads on fatigue crack growth of high strength steel wires
International Nuclear Information System (INIS)
Haag, J.; Reguly, A.; Strohaecker, T.R.
2013-01-01
Highlights: • A proof load process may be an option to increase the fatigue life of flexible pipelines. • There is possibility to produce plastic deformation at crack tip of tensile armor wires. • Controlled overloads provide effective crack growth retardation. • Crack growth retardation is also evident at higher stress ratios. - Abstract: Fatigue of the tensile armor wires is the main failure mode of flexible risers. Techniques to increase the life of these components are required to improve the processes safety on oil exploration. This work evaluates the crack growth retardation of high strength steel wires used in flexible pipelines. Fracture toughness tests were performed to establish the level of stress intensity factor wherein the wires present significant plastic deformation at the crack tip. The effect of tensile overload on fatigue behavior was assessed by fatigue crack growth testing under constant ΔK control and different overload ratios with two different load ratios. The outcomes show that the application of controlled overloads provides crack retardation and increases the fatigue life of the wires more than 31%. This behavior is also evident at stress ratio of 0.5, in spite of the crack closure effect being minimized by increasing the applied mean stress
Strength Tests on Hulls and Floats
Matthaes, K
1942-01-01
The present report deals with strength tests on hulls and floats intended in part for the collection of construction data for the design of these components and in part for the stress analysis of the finished hulls and floats.
Adapting proofs-as-programs the Curry-Howard protocol
Poernomo, Iman Hafiz; Crossley, John Newsome
2007-01-01
Details developments in the direction of a practical proofs-as-programs paradigm, which constitutes a set of approaches to developing programs from proofs in constructive logic with applications to industrial-scale, complex software engineering problems.
Proof test diagrams for Zerodur glass-ceramic
Tucker, D. S.
1991-01-01
Proof test diagrams for Zerodur glass-ceramics are calculated from available fracture mechanics data. It is shown that the environment has a large effect on minimum time-to-failure as predicted by proof test diagrams.
Enhancing paper strength by optimizing defect configuration
J.M. Considine; W. Skye; W. Chen; D. Matthys; David W. Vahey; K. Turner; R. Rowlands
2009-01-01
Poor formation in paper, as denoted by large local variation of mass, tends to reduce maximum tensile strength but has not been well characterized. The effect of grammage variation on tensile strength was studied by introducing carefully placed holes in tensile specimens made of three different paper materials. Previous researchers demonstrated that the point-stress...
Proof, rigour and informality : a virtue account of mathematical knowledge
Tanswell, Fenner Stanley
2017-01-01
This thesis is about the nature of proofs in mathematics as it is practiced, contrasting the informal proofs found in practice with formal proofs in formal systems. In the first chapter I present a new argument against the Formalist-Reductionist view that informal proofs are justified as rigorous and correct by corresponding to formal counterparts. The second chapter builds on this to reject arguments from Gödel's paradox and incompleteness theorems to the claim that mathematics is inherently...
Leadenham, Stephen; Erturk, Alper
2014-04-01
There has been growing interest in enabling wireless health and usage monitoring for rotorcraft applications, such as helicopter rotor systems. Large dynamic loads and acceleration fluctuations available in these environments make the implementation of vibration-based piezoelectric energy harvesters a very promising choice. However, such extreme loads transmitted to the harvester can also be detrimental to piezoelectric laminates and overall system reliability. Particularly flexible resonant cantilever configurations tuned to match the dominant excitation frequency can be subject to very large deformations and failure of brittle piezoelectric laminates due to excessive bending stresses at the root of the harvester. Design of resonant piezoelectric energy harvesters for use in these environments require nonlinear electroelastic dynamic modeling and strength-based analysis to maximize the power output while ensuring that the harvester is still functional. This paper presents a mathematical framework to design and analyze the dynamics of nonlinear flexible piezoelectric energy harvesters under large base acceleration levels. A strength-based limit is imposed to design the piezoelectric energy harvester with a proof mass while accounting for material, geometric, and dissipative nonlinearities, with a focus on two demonstrative case studies having the same linear fundamental resonance frequency but different overhang length and proof mass values. Experiments are conducted at different excitation levels for validation of the nonlinear design approach proposed in this work. The case studies in this work reveal that harvesters exhibiting similar behavior and power generation performance at low excitation levels (e.g. less than 0.1g) can have totally different strength-imposed performance limitations under high excitations (e.g. above 1g). Nonlinear modeling and strength-based design is necessary for such excitation levels especially when using resonant cantilevers with no
34 CFR 101.85 - Offer of proof.
2010-07-01
... 34 Education 1 2010-07-01 2010-07-01 false Offer of proof. 101.85 Section 101.85 Education... PRACTICE AND PROCEDURE FOR HEARINGS UNDER PART 100 OF THIS TITLE Hearing Procedures § 101.85 Offer of proof. An offer of proof made in connection with an objection taken to any ruling of the presiding officer...
7 CFR 15.122 - Offer of proof.
2010-01-01
... 7 Agriculture 1 2010-01-01 2010-01-01 false Offer of proof. 15.122 Section 15.122 Agriculture..., Decisions and Administrative Review Under the Civil Rights Act of 1964 Hearing Procedures § 15.122 Offer of proof. An offer of proof made in connection with an objection taken to any ruling of the hearing officer...
49 CFR 604.43 - Offer of proof.
2010-10-01
... 49 Transportation 7 2010-10-01 2010-10-01 false Offer of proof. 604.43 Section 604.43..., DEPARTMENT OF TRANSPORTATION CHARTER SERVICE Hearings. § 604.43 Offer of proof. A party whose evidence has... respond to the offer of proof, may offer the evidence on the record when filing an appeal. ...
36 CFR 1150.79 - Offer of proof.
2010-07-01
... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Offer of proof. 1150.79... BOARD PRACTICE AND PROCEDURES FOR COMPLIANCE HEARINGS Hearing Procedures § 1150.79 Offer of proof. An offer of proof made in connection with an objection taken to a ruling of the judge rejecting or...
Non-Well-Founded Proofs for the Grzegorczyk Modal Logic
Savateev, Yury; Shamkanov, Daniyar
2018-01-01
We present a sequent calculus for the Grzegorczyk modal logic Grz allowing cyclic and other non-well-founded proofs and obtain the cut-elimination theorem for it by constructing a continuous cut-elimination mapping acting on these proofs. As an application, we establish the Lyndon interpolation property for the logic Grz proof-theoretically.
16 CFR 614.1 - Appropriate proof of identity.
2010-01-01
... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Appropriate proof of identity. 614.1 Section... IDENTITY § 614.1 Appropriate proof of identity. (a) Consumer reporting agencies shall develop and implement reasonable requirements for what information consumers shall provide to constitute proof of identity for...
The direct Flow parametric Proof of Gauss' Divergence Theorem revisited
DEFF Research Database (Denmark)
Markvorsen, Steen
The standard proof of the divergence theorem in undergraduate calculus courses covers the theorem for static domains between two graph surfaces. We show that within first year undergraduate curriculum, the flow proof of the dynamic version of the divergence theorem - which is usually considered...... we apply the key instrumental concepts and verify the various steps towards this alternative proof of the divergence theorem....
How Mathematicians Determine if an Argument Is a Valid Proof
Weber, Keith
2008-01-01
The purpose of this article is to investigate the mathematical practice of proof validation--that is, the act of determining whether an argument constitutes a valid proof. The results of a study with 8 mathematicians are reported. The mathematicians were observed as they read purported mathematical proofs and made judgments about their validity;…
Mathematicians' Perspectives on Features of a Good Pedagogical Proof
Lai, Yvonne; Weber, Keith; Mejia-Ramos, Juan Pablo
2012-01-01
In this article, we report two studies investigating what mathematicians value in a pedagogical proof. Study 1 is a qualitative study of how eight mathematicians revised two proofs that would be presented in a course for mathematics majors. These mathematicians thought that introductory and concluding sentences should be included in the proofs,…
A Calculus of Circular Proofs and its Categorical Semantics
DEFF Research Database (Denmark)
Santocanale, Luigi
2002-01-01
We present a calculus of "circular proofs": the graph underlying a proof is not a finite tree but instead it is allowed to contain a certain amount of cycles.The main challenge in developing a theory for the calculus is to define the semantics of proofs, since the usual method by induction...
29 CFR 1919.31 - Proof tests-loose gear.
2010-07-01
... 29 Labor 7 2010-07-01 2010-07-01 false Proof tests-loose gear. 1919.31 Section 1919.31 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels: Tests and Proof Loads; Heat Treatment; Competent Persons § 1919.31 Proof tests—loose gear. (a) Chains, rings, shackles and other loose gear (whether...
Proviola: a tool for proof re-animation
Tankink, C.; Geuvers, J.H.; McKinna, J.; Wiedijk, F.; Autexier, S.; Calmet, J.; Delahaye, D.; Ion, P.D.F.; Rideau, L.; Rioboo, R.; Sexton, A.P.
2010-01-01
To improve on existing models of interaction with a proof assistant (PA), in particular for storage and replay of proofs, we introduce three related concepts, those of: a proof movie, consisting of frames which record both user input and the corresponding PA response; a camera, which films a user’s
Exploring mathematics problem-solving and proof
Grieser, Daniel
2018-01-01
Have you ever faced a mathematical problem and had no idea how to approach it? Or perhaps you had an idea but got stuck halfway through? This book guides you in developing your creativity, as it takes you on a voyage of discovery into mathematics. Readers will not only learn strategies for solving problems and logical reasoning, but they will also learn about the importance of proofs and various proof techniques. Other topics covered include recursion, mathematical induction, graphs, counting, elementary number theory, and the pigeonhole, extremal and invariance principles. Designed to help students make the transition from secondary school to university level, this book provides readers with a refreshing look at mathematics and deep insights into universal principles that are valuable far beyond the scope of this book. Aimed especially at undergraduate and secondary school students as well as teachers, this book will appeal to anyone interested in mathematics. Only basic secondary school mathematics is requi...
Multiparty Session Types as Coherence Proofs
DEFF Research Database (Denmark)
Carbone, Marco; Montesi, Fabrizio; Schürmann, Carsten
2015-01-01
We propose a Curry-Howard correspondence between a language for programming multiparty sessions and a generalisation of Classical Linear Logic (CLL). In this framework, propositions correspond to the local behaviour of a participant in a multiparty session type, proofs to processes, and proof...... normalisation to executing communications. Our key contribution is generalising duality, from CLL, to a new notion of n-ary compatibility, called coherence. Building on coherence as a principle of compositionality, we generalise the cut rule of CLL to a new rule for composing many processes communicating...... in a multiparty session. We prove the soundness of our model by showing the admissibility of our new rule, which entails deadlock-freedom via our correspondence....
Consistency Anchor Formalization and Correctness Proofs
Miguel, Correia; Bessani, Alysson
2014-01-01
This is report contains the formal proofs for the techniques for increasing the consistency of cloud storage as presented in "Bessani et al. SCFS: A Cloud-backed File System. Proc. of the 2014 USENIX Annual Technical Conference. June 2014." The consistency anchor technique allows one to increase the consistency provided by eventually consistent cloud storage services like Amazon S3. This technique has been used in the SCFS (Shared Cloud File System) cloud-backed file system for solving rea...
Kant's Transcendental Arguments as Conceptual Proofs | Stapleford ...
African Journals Online (AJOL)
The paper is an attempt to explain what a transcendental argument is for Kant. The interpretation is based on a reading of the “Discipline of Pure Reason,” sections 1 and 4, of the first Critique. The author first identifies several statements that Kant makes about the method of proof he followed in the “Analytic of Principles,” ...
Strength properties of concrete at elevated temperatures
International Nuclear Information System (INIS)
Freskakis, G.N.; Burrow, R.C.; Debbas, E.B.
1979-01-01
A study is presented concerning the compressive strength, modulus of elasticity, and stress-strain relationships of concrete at elevated temperatures. A review of published results provides information for the development of upper and lower bound relationships for compressive strength and the modulus of elasticity and establishes exposure conditions for a lower bound thermal response. The relationships developed from the literature review are confirmed by the results of a verification test program. The strength and elasticity relationships provide a basis for the development of design stress-strain curves for concrete exposed to elevated temperatures
An illustration of the explanatory and discovery functions of proof
Directory of Open Access Journals (Sweden)
Michael de Villiers
2012-11-01
Full Text Available This article provides an illustration of the explanatory and discovery functions of proof with an original geometric conjecture made by a Grade 11 student. After logically explaining (proving the result geometrically and algebraically, the result is generalised to other polygons by further reflection on the proof(s. Different proofs are given, each giving different insights that lead to further generalisations. The underlying heuristic reasoning is carefully described in order to provide an exemplar for designing learning trajectories to engage students with these functions of proof.
On the proof of the first Carnot theorem in thermodynamics
International Nuclear Information System (INIS)
Morad, M R; Momeni, F
2013-01-01
The proof of the first Carnot theorem in classical thermodynamics is revisited in this study. The underlying conditions of a general proof of this principle presented by Senft (1978 Phys. Educ. 13 35–37) are explored and discussed. These conditions are analysed in more detail using a physical description of heat and work to present a simpler proof of the first principle prior to using the violation of the second law of thermodynamics. Finally, a new simple proof is also presented based on Gibbs relation. This discussion will benefit the teaching of classical thermodynamics and promote better understanding of the proof of the first Carnot theorem in general form. (paper)
2nd International Conference on Proof-Theoretic Semantics
Schroeder-Heister, Peter
2016-01-01
This volume is the first ever collection devoted to the field of proof-theoretic semantics. Contributions address topics including the systematics of introduction and elimination rules and proofs of normalization, the categorial characterization of deductions, the relation between Heyting's and Gentzen's approaches to meaning, knowability paradoxes, proof-theoretic foundations of set theory, Dummett's justification of logical laws, Kreisel's theory of constructions, paradoxical reasoning, and the defence of model theory. The field of proof-theoretic semantics has existed for almost 50 years, but the term itself was proposed by Schroeder-Heister in the 1980s. Proof-theoretic semantics explains the meaning of linguistic expressions in general and of logical constants in particular in terms of the notion of proof. This volume emerges from presentations at the Second International Conference on Proof-Theoretic Semantics in Tübingen in 2013, where contributing authors were asked to provide a self-contained descri...
Strength and life under creeping
International Nuclear Information System (INIS)
Pospishil, B.
1982-01-01
Certain examples of the application of the Lepin modified creep model, which are of interest from technical viewpoint, are presented. Mathematical solution of the dependence of strength limit at elevated temperatures on creep characteristics is obtained. Tensile test at elevated temperatures is a particular case of creep or relaxation and both strength limit and conventional yield strength at elevated temperatures are completely determined by parameters of state equations during creep. The equation of fracture summing during creep is confirmed not only by the experiment data when stresses change sporadically, but also by good reflection of durability curve using the system of equations. The system presented on the basis of parameters of the equations obtained on any part of durability curve, permits to forecast the following parameters of creep: strain, strain rate, life time, strain in the process of fracture. Tensile test at elevated temperature is advisable as an addition when determining creep curves (time-strain curves) [ru
On Federated and Proof Of Validation Based Consensus Algorithms In Blockchain
Ambili, K. N.; Sindhu, M.; Sethumadhavan, M.
2017-08-01
Almost all real world activities have been digitized and there are various client server architecture based systems in place to handle them. These are all based on trust on third parties. There is an active attempt to successfully implement blockchain based systems which ensures that the IT systems are immutable, double spending is avoided and cryptographic strength is provided to them. A successful implementation of blockchain as backbone of existing information technology systems is bound to eliminate various types of fraud and ensure quicker delivery of the item on trade. To adapt IT systems to blockchain architecture, an efficient consensus algorithm need to be designed. Blockchain based on proof of work first came up as the backbone of cryptocurrency. After this, several other methods with variety of interesting features have come up. In this paper, we conduct a survey on existing attempts to achieve consensus in block chain. A federated consensus method and a proof of validation method are being compared.
Proof-testing and probabilistic lifetime estimation of glass fibers for sensor applications.
Komachiya, M; Minamitani, R; Fumino, T; Sakaguchi, T; Watanabe, S
1999-05-01
The mechanical reliability of sensing glass fiber is one of the important problems in the practical use of fiber-optic sensors. To ensure long-term reliability on a mass-production level, a method of proof-testing is applied to a sensing glass fiber that will be subjected to mechanical deformation in its service situation. We propose to employ a higher strain level (screening level) in the proof-testing with a fiber-recoating technique that can suppress excessive damage during the testing. We consider a standard lifetime of 15 years of automotive applications and ensure a practical level of failure probability by a model calculation by using the strength data of a prototype fiber with the method of fracture-mechanics theory.
Energy Technology Data Exchange (ETDEWEB)
Nihei, K.; Inamura, F.; Koe, S. [Kawasaki Heavy Industries, Ltd., Kobe (Japan)
1996-12-31
There has been tried to apply unified assessment method using hot spot stress, which is effective to evaluate fatigue strength of fillet welded structures for ships and marine structures. This method can be applied to complicated structures and is independent of welding processes. In this study, first, stress analysis has been conducted for two-dimensional fillet welded joint models with various combinations of plate thickness and weld leg length of general fillet structures by means of boundary element method. Then, critical position, which is not affected by local stress concentration due to bead, was determined from the detailed stress distribution in the vicinity of weld toe. As a result, a general equation has been proposed to estimate the hot spot stress by one-point representative method. Second, the fatigue tests of typical fillet welded joints have been conducted by applying this method. Consequently, it was demonstrated that the unified fatigue strength can be evaluated by the S-N data based on hot spot stress range determined from the proposed equation, independent of structural stress concentration. 22 refs., 14 figs.
Energy Technology Data Exchange (ETDEWEB)
Nihei, K; Inamura, F; Koe, S [Kawasaki Heavy Industries, Ltd., Kobe (Japan)
1997-12-31
There has been tried to apply unified assessment method using hot spot stress, which is effective to evaluate fatigue strength of fillet welded structures for ships and marine structures. This method can be applied to complicated structures and is independent of welding processes. In this study, first, stress analysis has been conducted for two-dimensional fillet welded joint models with various combinations of plate thickness and weld leg length of general fillet structures by means of boundary element method. Then, critical position, which is not affected by local stress concentration due to bead, was determined from the detailed stress distribution in the vicinity of weld toe. As a result, a general equation has been proposed to estimate the hot spot stress by one-point representative method. Second, the fatigue tests of typical fillet welded joints have been conducted by applying this method. Consequently, it was demonstrated that the unified fatigue strength can be evaluated by the S-N data based on hot spot stress range determined from the proposed equation, independent of structural stress concentration. 22 refs., 14 figs.
ProofJudge: Automated Proof Judging Tool for Learning Mathematical Logic
DEFF Research Database (Denmark)
Villadsen, Jørgen
2015-01-01
Today we have software in many artefacts, from medical devices to cars and airplanes, and the software must not only be efficient and intelligent but also reliable and secure. Tests can show the presence of bugs but cannot guarantee their absence. A machine-checked proof using mathematical logic...... pen and paper because no adequate tool was available. The learning problem is how to make abstract concepts of logic as concrete as possible. ProofJudge is a computer system and teaching approach for teaching mathematical logic and automated reasoning which augments the e-learning tool NaDeA (Natural...
ProofJudge: Automated Proof Judging Tool for Learning Mathematical Logic
DEFF Research Database (Denmark)
Villadsen, Jørgen
2016-01-01
Today we have software in many artefacts, from medical devices to cars and airplanes, and the software must not only be efficient and intelligent but also reliable and secure. Tests can show the presence of bugs but cannot guarantee their absence. A machine-checked proof using mathematical logic...... using pen and paper because no adequate tool was available. The learning problem is how to make abstract concepts of logic as concrete as possible. ProofJudge is a computer system and teaching approach for teaching mathematical logic and automated reasoning which augments the e-learning tool Na...
The Proof is in the Pudding The Changing Nature of Mathematical Proof
Krantz, Steven G
2011-01-01
This text explores the many transformations that the mathematical proof has undergone from its inception to its versatile, present-day use, considering the advent of high-speed computing machines. Though there are many truths to be discovered in this book, by the end it is clear that there is no formalized approach or standard method of discovery to date. Most of the proofs are discussed in detail with figures and equations accompanying them, allowing both the professional mathematician and those less familiar with mathematics to derive the same joy from reading this book.
New climate-proof cropping systems in dry areas of the Mediterranean region
DEFF Research Database (Denmark)
Jacobsen, Sven-Erik
2014-01-01
severe consequences of climate changes, under influence of multiple abiotic stresses. These stresses are becoming even more pronounced under changing climate, resulting in drier conditions, increasing temperatures and greater variability, causing desertification. This topic has been addressed in the EU...... FP7 project entitled 'Sustainable water use securing food production in dry areas of the Mediterranean region (SWUP-MED)' working on climate-proof cropping systems in Morocco, Syria, Turkey and southern Europe, collaborating with UK, Denmark and Australia. The results are valid for other parts...
DEFF Research Database (Denmark)
Ledertoug, Mette Marie
In the Ph.D-project ͚Strengths-based Learning - Children͛s character strengths as a means to their learning potential͛ 750 Danish children have assessed ͚The Strength Compass͛ in order to identify their strengths and to create awareness of strengths. This was followed by a strengths......-based intervention program in order to explore the strengths. Finally different methods to apply the strength in everyday life at school were applied. The paper presentation will show the results for strengths display for children aged 6-16 in different categories: Different age groups: Are the same strengths...... present in both small children and youths? Gender: Do the results show differences between the two genders? Danish as a mother- tongue language: Do the results show any differences in the strengths display when considering different language and cultural backgrounds? Children with Special Needs: Do...
ATAC Process Proof of Concept Final Report
Energy Technology Data Exchange (ETDEWEB)
Bri Rolston; Sarah Freeman
2014-03-01
Researchers at INL with funding from the Department of Energy’s Office of Electricity Delivery and Energy Reliability (DOE-OE) evaluated a novel approach for near real-time consumption of threat intelligence. Demonstration testing in an industry environment supported the development of this new process to assist the electric sector in securing their critical networks. This report provides the reader with an understanding of the methods used during this proof of concept project. The processes and templates were further advanced with an industry partner during an onsite assessment. This report concludes with lessons learned and a roadmap for final development of these materials for use by industry.
Open Assessment of Proofs in Litigation
Directory of Open Access Journals (Sweden)
Kaltrina Zekolli
2017-01-01
Full Text Available The key of existence and success in all domains of life to the entity of justice is the thorough compliance to the truth and justice. Therefore when a certain right is violated, liable or challenged entrusted to solve that, are the institutions of justice, rather the courts. Courts are competent to find the right path towards the truth applying different methods with intention to satisfy the justice. In this paper special attention we dedicated to the method of open assessment of proofs in litigation, that in fact is the subject of this research.
Duan's fixed point theorem: Proof and generalization
Directory of Open Access Journals (Sweden)
Arkowitz Martin
2006-01-01
Full Text Available Let be an H-space of the homotopy type of a connected, finite CW-complex, any map and the th power map. Duan proved that has a fixed point if . We give a new, short and elementary proof of this. We then use rational homotopy to generalize to spaces whose rational cohomology is the tensor product of an exterior algebra on odd dimensional generators with the tensor product of truncated polynomial algebras on even dimensional generators. The role of the power map is played by a -structure as defined by Hemmi-Morisugi-Ooshima. The conclusion is that and each has a fixed point.
Autonomous intelligent cars: proof that the EPSRC Principles are future-proof
de Bruin, R.W.; de Cock Buning, M.
2017-01-01
Principle 2 of the EPSRC’s principles of robotics (AISB workshop on PrinciplesofRobotics, 2016) proves to be future proof when applied to the current state of the art of law and technology surrounding autonomous intelligent cars (AICs). Humans, not AICS, are responsible agents. AICs should be
Semantic Contamination and Mathematical Proof: Can a Non-Proof Prove?
Mejia-Ramos, Juan Pablo; Inglis, Matthew
2011-01-01
The way words are used in natural language can influence how the same words are understood by students in formal educational contexts. Here we argue that this so-called semantic contamination effect plays a role in determining how students engage with mathematical proof, a fundamental aspect of learning mathematics. Analyses of responses to…
Secondary Teachers' Knowledge of Elementary Number Theory Proofs: The Case of General-Cover Proofs
Tabach, Michal; Levenson, Esther; Barkai, Ruthi; Tsamir, Pessia; Tirosh, Dina; Dreyfus, Tommy
2011-01-01
In light of recent reform recommendations, teachers are expected to turn proofs and proving into an ongoing component of their classroom practice. Two questions emerging from this requirement are: Is the mathematical knowledge of high school teachers sufficient to prove various kinds of statements? Does teachers' knowledge allow them to determine…
43 CFR 4.840 - Offer of proof.
2010-10-01
... the Interior-Effectuation of Title VI of the Civil Rights Act of 1964 Hearing § 4.840 Offer of proof. An offer of proof made in connection with an objection taken to any ruling of the administrative law... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Offer of proof. 4.840 Section 4.840 Public...
A portable virtual machine target for proof-carrying code
DEFF Research Database (Denmark)
Franz, Michael; Chandra, Deepak; Gal, Andreas
2005-01-01
Virtual Machines (VMs) and Proof-Carrying Code (PCC) are two techniques that have been used independently to provide safety for (mobile) code. Existing virtual machines, such as the Java VM, have several drawbacks: First, the effort required for safety verification is considerable. Second and mor...... simultaneously providing efficient justin-time compilation and target-machine independence. In particular, our approach reduces the complexity of the required proofs, resulting in fewer proof obligations that need to be discharged at the target machine....
The direct Flow parametric Proof of Gauss' Divergence Theorem revisited
Markvorsen, Steen
2006-01-01
The standard proof of the divergence theorem in undergraduate calculus courses covers the theorem for static domains between two graph surfaces. We show that within first year undergraduate curriculum, the flow proof of the dynamic version of the divergence theorem - which is usually considered only much later in more advanced math courses - is comprehensible with only a little extension of the first year curriculum. Moreover, it is more intuitive than the static proof. We support this intuit...
A String of Pearls: Proofs of Fermat's Little Theorem
Directory of Open Access Journals (Sweden)
Hing Lun Chan
2013-01-01
Full Text Available We discuss mechanised proofs of Fermat's Little Theorem in a variety of styles, focusing in particular on an elegant combinatorial ``necklace'' proof that has not been mechanised previously.What is elegant in prose turns out to be long-winded mechanically, and so we examine the effect of explicitly appealing to group theory. This has pleasant consequences both for the necklace proof, and also for some of the direct number-theoretic approaches.
A Concise and Direct Proof of "Fermat's Last Theorem"
Ellman, Roger
1998-01-01
The recently developed proof of Fermat's Last Theorem is very lengthy and difficult, so much so as to be beyond all but a small body of specialists. While certainly of value in the developments that resulted, that proof could not be, nor was offered as being, possibly the proof Fermat had in mind. The present proof being brief, direct and concise is a candidate for being what Fermat had in mind. It is also completely accessible to any one trained in common algebra. That critical suggestions o...
DEFF Research Database (Denmark)
Ledertoug, Mette Marie
of agreement/disagreement. Also the child/teacher is asked whether the actual strength is important and if he or she has the possibilities to apply the strength in the school. In a PhDproject ‘Strengths-based Learning - Children’s Character Strengths as Means to their Learning Potential’ 750 Danish children......Individual paper presentation: The ‘Strength Compass’. The results of a PhDresearch project among schoolchildren (age 6-16) identifying VIAstrengths concerning age, gender, mother-tongue-langue and possible child psychiatric diagnosis. Strengths-based interventions in schools have a theoretical...... Psychological Publishing Company. ‘The Strength Compass’ is a computer/Ipad based qualitative tool to identify the strengths of a child by a self-survey or a teacher’s survey. It is designed as a visual analogue scale with a statement of the strength in which the child/teacher may declare the degree...
Kinetics model of bainitic transformation with stress
Zhou, Mingxing; Xu, Guang; Hu, Haijiang; Yuan, Qing; Tian, Junyu
2018-01-01
Thermal simulations were conducted on a Gleeble 3800 simulator. The main purpose is to investigate the effects of stress on the kinetics of bainitic transformation in a Fe-C-Mn-Si advanced high strength bainitic steel. Previous studies on modeling the kinetics of stress affected bainitic transformation only considered the stress below the yield strength of prior austenite. In the present study, the stress above the yield strength of prior austenite is taken into account. A new kinetics model of bainitic transformation dependent on the stress (including the stresses below and above the yield strength of prior austenite) and the transformation temperature is proposed. The new model presents a good agreement with experimental results. In addition, it is found that the acceleration degree of stress on bainitic transformation increases with the stress whether its magnitude is below or above the yield strength of austenite, but the increasing rate gradually slows down when the stress is above the yield strength of austenite.
Fracture flow modelling. Proof of evidence
International Nuclear Information System (INIS)
Hencher, S.R.
1996-01-01
Proof of Evidence by an expert witness is presented in support of the case by Friends of the Earth (FOE) against the proposed construction by UK Nirex Ltd of an underground Rock Characterisation Facility (RCF) at a site in the Sellafield area. The RCF is part of an investigation by Nirex into a suitable site for an underground repository for the disposal of radioactive waste. The objections were raised at a Planning Inquiry in 1995. The evidence points out that current understanding of the factors which control flow through a network of interconnecting fractures, such as that at the Sellafield site, is at a very early stage of development. Neither are the methods of investigation and analysis required for a post-closure performance assessment (PCPA) for a repository well developed. These issues are being investigated in international underground research laboratories but the proposed RCF is intended to be confirmatory rather than experimental. (23 references). (UK)
Tritium proof-of-principle injector experiment
International Nuclear Information System (INIS)
Fisher, P.W.; Milora, S.L.; Combs, S.K.; Carlson, R.V.; Coffin, D.O.
1988-01-01
The Tritium Proof-of-Principle (TPOP) pellet injector was designed and built by Oak Ridge National Laboratory (ORNL) to evaluate the production and acceleration of tritium pellets for fueling future fision reactors. The injector uses the pipe-gun concept to form pellets directly in a short liquid-helium-cooled section of the barrel. Pellets are accelerated by using high-pressure hydrogen supplied from a fast solenoid valve. A versatile, tritium-compatible gas-handling system provides all of the functions needed to operate the gun, including feed gas pressure control and flow control, plus helium separation and preparation of mixtures. These systems are contained in a glovebox for secondary containment of tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory (LANL). 18 refs., 3 figs
Complete proof systems for weighted modal logic
DEFF Research Database (Denmark)
Larsen, Kim G.; Mardare, Radu
2014-01-01
(WML) is a multi-modal logic that expresses qualitative and quantitative properties of WTSs. While WML has been studied in various contexts and for various application domains, no proof system has been developed for it. In this paper we solve this open problem and propose both weak-complete and strong......The weighted transition systems (WTS) considered in this paper are transition systems having both states and transitions labeled with real numbers: the state labels denote quantitative resources, while the transition labels denote costs of transitions in terms of resources. Weighted Modal Logic....... This work emphasizes a series of similarities between WML and the probabilistic/stochastic modal logics for Markov processes and Harsanyi type spaces, such as the use of particular infinitary rules to guarantee the strong-completeness....
Duan's fixed point theorem: proof and generalization
Directory of Open Access Journals (Sweden)
2006-01-01
Full Text Available Let X be an H-space of the homotopy type of a connected, finite CW-complex, f:X→X any map and p k :X→X the k th power map. Duan proved that p k f :X→X has a fixed point if k≥2 . We give a new, short and elementary proof of this. We then use rational homotopy to generalize to spaces X whose rational cohomology is the tensor product of an exterior algebra on odd dimensional generators with the tensor product of truncated polynomial algebras on even dimensional generators. The role of the power map is played by a θ -structure μ θ :X→X as defined by Hemmi-Morisugi-Ooshima. The conclusion is that μ θ f and f μ θ each has a fixed point.
Soft magnetic tweezers: a proof of principle.
Mosconi, Francesco; Allemand, Jean François; Croquette, Vincent
2011-03-01
We present here the principle of soft magnetic tweezers which improve the traditional magnetic tweezers allowing the simultaneous application and measurement of an arbitrary torque to a deoxyribonucleic acid (DNA) molecule. They take advantage of a nonlinear coupling regime that appears when a fast rotating magnetic field is applied to a superparamagnetic bead immersed in a viscous fluid. In this work, we present the development of the technique and we compare it with other techniques capable of measuring the torque applied to the DNA molecule. In this proof of principle, we use standard electromagnets to achieve our experiments. Despite technical difficulties related to the present implementation of these electromagnets, the agreement of measurements with previous experiments is remarkable. Finally, we propose a simple way to modify the experimental design of electromagnets that should bring the performances of the device to a competitive level.
Design considerations for prepress color proof measurement
Spooner, David L.
1993-06-01
For our purposes, we needed colorimetric measurements or, better yet, spectral reflectance data. Our survey of commercially available instruments identified one spectrocolorimeter, the Hunter PICS (manufactured by Hunter Associates Laboratory, Inc.), which could be programmed to automatically measure the color (and spectral reflectance) of large numbers of samples on a proof sheet. After an evaluation of this instrument, which included measuring over 10,000 exhibits, it was decided that the unit did not fully meet our needs. This resulted in a decision to integrate another instrument, the Byk-Gardner Color Machine (manufactured by Byk-Gardner, Inc.), with an x-y positioning mechanism. This paper describes the design considerations used in the development of our color measurement system.
Proofs and generalizations of the pythagorean theorem
Directory of Open Access Journals (Sweden)
Lialda B. Cavalcanti
2011-01-01
Full Text Available This article explores a topic developed by a group of researchers of the Science and Technology Teaching School of Instituto Federal de Pernambuco, Brazil (IFPE, in assistance to the development of the Mathematics Practical and Teaching Laboratory of the distance learning Teaching Licensure, financed by the Universidad Abierta de Brasil. In this article, we describe the peculiarities present in the proofs of the Pythagorean theorem with the purpose of illustrating some of these methods. The selection of these peculiarities was founded and based on the comparison of areas by means of the superimposition of geometrical shapes and used several different class resources. Some generalizations of this important theorem in mathematical problem-solving are also shown.
The theoretical tensile strength of fcc crystals predicted from shear strength calculations
International Nuclear Information System (INIS)
Cerny, M; Pokluda, J
2009-01-01
This work presents a simple way of estimating uniaxial tensile strength on the basis of theoretical shear strength calculations, taking into account its dependence on a superimposed normal stress. The presented procedure enables us to avoid complicated and time-consuming analyses of elastic stability of crystals under tensile loading. The atomistic simulations of coupled shear and tensile deformations in cubic crystals are performed using first principles computational code based on pseudo-potentials and the plane wave basis set. Six fcc crystals are subjected to shear deformations in convenient slip systems and a special relaxation procedure controls the stress tensor. The obtained dependence of the ideal shear strength on the normal tensile stress seems to be almost linearly decreasing for all investigated crystals. Taking these results into account, the uniaxial tensile strength values in three crystallographic directions were evaluated by assuming a collapse of the weakest shear system. Calculated strengths for and loading were found to be mostly lower than previously calculated stresses related to tensile instability but rather close to those obtained by means of the shear instability analysis. On the other hand, the strengths for loading almost match the stresses related to tensile instability.
Influence of multiaxial preloading on the strength of concrete
International Nuclear Information System (INIS)
Linse, D.
1975-01-01
In a preliminary study about the influence of the loading direction discs of 20/20/5 cm were loaded at different stress-rates in one direction, then unloaded and loaded up to failure again. Two series of each about 15 specimens were tested: the first series was reloaded in the same direction as it was loaded before. If the preloading was not greater than about 90% of the original short-term uniaxial strength βsub(p), one could achieve in the second loading a higher strength than the strength βsub(p). The second series was reloaded normal to the direction of preloading. By an other series of about 50 specimens the influence of triaxial preloading on the uniaxial strength of concrete was tested. Cubes of 10cm were loaded by brush bearing platens up to a stress which was maximally three times higher than the uniaxial short-term strength βsub(p), then unloaded and tested again under uniaxial compression. The achieved ultimate strength of the cubes at the second loading was obviously dependent upon the stress-state and the stress-rate of the preloading. Multiaxial preloading which is far below the ultimate multiaxial strength can considerably defect the remaining strength of concrete. The decrease in strength was defined by the reduction of the uniaxial strength. It can be assumed that the remaining multiaxial strength is reduced at least to the same rate. Further tests are planned
The direct liquefaction proof of concept program
Energy Technology Data Exchange (ETDEWEB)
Comolli, A.G.; Lee, L.K.; Pradhan, V.R.; Stalzer, R.H. [New York & Puritan Avenues, Lawrenceville, NJ (United States)
1995-12-31
The goal of the Proof of Concept (POC) Program is to develop Direct Coal Liquefaction and associated transitional technologies towards commercial readiness for economically producing premium liquid fuels from coal in an environmentally acceptable manner. The program focuses on developing the two-stage liquefaction (TSL) process by utilizing geographically strategic feedstocks, commercially feasible catalysts, new prototype equipment, and testing co-processing or alternate feedstocks and improved process configurations. Other high priority objectives include dispersed catalyst studies, demonstrating low rank coal liquefaction without solids deposition, improving distillate yields on a unit reactor volume basis, demonstrating ebullated bed operations while obtaining scale-up data, demonstrating optimum catalyst consumption using new concepts (e.g. regeneration, cascading), producing premium products through on-line hydrotreating, demonstrating improved hydrogen utilization for low rank coals using novel heteroatom removal methods, defining and demonstrating two-stage product properties for upgrading; demonstrating efficient and economic solid separation methods, examining the merits of integrated coal cleaning, demonstrating co-processing, studying interactions between the preheater and first and second-stage reactors, improving process operability by testing and incorporating advanced equipment and instrumentation, and demonstrating operation with alternate coal feedstocks. During the past two years major PDU Proof of Concept runs were completed. POC-1 with Illinois No. 6 coal and POC-2 with Black Thunder sub-bituminous coal. Results from these operations are continuing under review and the products are being further refined and upgraded. This paper will update the results from these operations and discuss future plans for the POC program.
Modeling of Sylgard Adhesive Strength
Energy Technology Data Exchange (ETDEWEB)
Stevens, Ralph Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-02-03
Sylgard is the name of a silicone elastomeric potting material manufactured by Dow Corning Corporation.1 Although the manufacturer cites its low adhesive strength as a feature of this product, thin layers of Sylgard do in fact have a non-negligible strength, which has been measured in recent tensile and shear debonding tests. The adhesive strength of thin layers of Sylgard potting material can be important in applications in which components having signi cantly di erent thermal expansion properties are potted together, and the potted assembly is subjected to temperature changes. The tensile and shear tractions developed on the potted surfaces of the components can cause signi cant internal stresses, particularly for components made of low-strength materials with a high area-to-volume ratio. This report is organized as follows: recent Sylgard debonding tests are rst brie y summarized, with particular attention to the adhesion between Sylgard and PBX 9501, and also between Sylgard and aluminum. Next, the type of numerical model that will be used to simulate the debonding behavior exhibited in these tests is described. Then the calibration of the debonding model will be illustrated. Finally, the method by which the model parameters are adjusted (scaled) to be applicable to other, non- tested bond thicknesses is summarized, and all parameters of the model (scaled and unscaled) are presented so that other investigators can reproduce all of the simulations described in this report as well as simulations of the application of interest.
Numerical Model of High Strength Concrete
Wang, R. Z.; Wang, C. Y.; Lin, Y. L.
2018-03-01
The purpose of this paper is to present a three-dimensional constitutive model based on the concept of equivalent uniaxial strain. closed Menetrey-Willam (CMW) failure surfaces which combined with Menetrey-Willam meridian and the cap model are introduced in this paper. Saenz stress-strain model is applied and adjusted by the ultimate strength parameters from CMW failure surface to reflect the latest stress or strain condition. The high strength concrete (HSC) under tri-axial non-proportional loading is considered and the model in this paper performed a good prediction.
International Nuclear Information System (INIS)
Ravi Sankar, A; Lahiri, S K; Das, S
2009-01-01
Performance enhancement of a silicon MEMS piezoresistive single axis accelerometer with electroplated gold on a proof mass is presented in this paper. The fabricated accelerometer device consists of a heavy proof mass supported by four thin flexures. Boron-diffused piezoresistors located near the fixed ends of the flexures are used for sensing the developed stress and hence acceleration. Performance enhancement is achieved by electroplating a gold mass of 20 µm thickness on top of the proof mass. A commercially available sulfite-based solution TSG-250(TM) was used for the electroplating process. Aluminum metal lines were used to form a Wheatstone bridge for signal pick-up. To avoid galvanic corrosion between two dissimilar metals having contact in an electrolyte, a shadow mask technique was used to selectively deposit a Cr/Au seed layer on an insulator atop the proof mass for subsequent electrodeposition. Bulk micromachining was performed using a 5% dual-doped TMAH solution. Fabricated devices with different electroplated gold areas were tested up to ±13 g acceleration. For electroplated gold dimensions of 2500 µm × 2500 µm × 20 µm on a proof mass, sensitivity along the Z-axis is increased by 21.8% as compared to the structure without gold. Off-axis sensitivities along the X- and Y-axes are reduced by 7.6% and 6.9%, respectively
The explosion-proof container, satisfying the IAEA norms on safety
International Nuclear Information System (INIS)
Syrunin, M.A.; Fedorenko, A.G.; Ivanov, A.G.; Abakumov, A.I.; Nizovtsev, P.N.; Loginov, P.G.; Smolyakov, A.A.; Solov'ev, V.P.
1998-01-01
Safety of radioactive materials (RM) transportation is under strict control of the international norms of IAEA, aimed to ensure non-proliferation of hazardous materials in the environments. At the same time the nuclear countries use much more dangerous transportations of two types of hazardous materials. Probability of emergency explosion of high explosives (HE) during transportation and storage of such constructions is not equal to zero. HE explosion can be caused by: 1)excess of mechanical effects, allowable by the norms, on an explosive 2)lightening or fire 3)terrorist attack 4)radio controlled or time controlled mechanism in case of the terrorist device. It is obvious that an accident with explosion HE element of the nuclear weapon in an usual container, which meets the IAEA norms, but is not explosion-proof, will result in its destruction, RM dispersal, and inadmissible pollution of the environments. Therefore, it is urgent need for development of the container, which is able to withstand explosion of HE, placed in it, and to confine released RM inside of it. The experimental prototype of the load-bearing shell of the explosion-proof container (EC) can be the successfully tested spherical steel - glass plastic shell, having high-strength throats and lids. Having weight of 45-50 kg it is able to withstand internal explosion with energy more than 1.4 kg of the TNT equivalent. To preserve the explosion-proofness property in the abnormal environments during transportation, the explosion-proof container should be placed in the protective supporting transport device or the transport container (TC), consisting of the external thin-walled steel shell and the damping heat-proof layer from heat-resistant foam plastic. To justify the design parameters of such container, the tests for development and revision of the numerical model parameters were carried out. With use of this model the calculations were performed to calculate loads and the container response to 1
Accelerated Strength Testing of Thermoplastic Composites
Reeder, J. R.; Allen, D. H.; Bradley, W. L.
1998-01-01
Constant ramp strength tests on unidirectional thermoplastic composite specimens oriented in the 90 deg. direction were conducted at constant temperatures ranging from 149 C to 232 C. Ramp rates spanning 5 orders of magnitude were tested so that failures occurred in the range from 0.5 sec. to 24 hrs. (0.5 to 100,000 MPa/sec). Below 204 C, time-temperature superposition held allowing strength at longer times to be estimated from strength tests at shorter times but higher temperatures. The data indicated that a 50% drop in strength might be expected for this material when the test time is increased by 9 orders of magnitude. The shift factors derived from compliance data applied well to the strength results. To explain the link between compliance and strength, a viscoelastic fracture model was investigated. The model, which used compliance as input, was found to fit the strength data only if the critical fracture energy was allowed to vary with temperature reduced stress rate. This variation in the critical parameter severely limits its use in developing a robust time-dependent strength model. The significance of this research is therefore seen as providing both the indication that a more versatile acceleration method for strength can be developed and the evidence that such a method is needed.
A New Small Emendation of Gödel's Ontological Proof
Czech Academy of Sciences Publication Activity Database
Hájek, Petr
2002-01-01
Roč. 71, č. 2 (2002), s. 149-164 ISSN 0039-3215 R&D Projects: GA MŠk LN00A056 Keywords : ontological proof * Gödel proof * modal logic * comprehension * positive properties Subject RIV: BA - General Mathematics
14 CFR 13.225 - Offer of proof.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Offer of proof. 13.225 Section 13.225... INVESTIGATIVE AND ENFORCEMENT PROCEDURES Rules of Practice in FAA Civil Penalty Actions § 13.225 Offer of proof. A party whose evidence has been excluded by a ruling of the administrative law judge may offer the...
14 CFR 406.155 - Offer of proof.
2010-01-01
... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Offer of proof. 406.155 Section 406.155... Transportation Adjudications § 406.155 Offer of proof. A party whose evidence has been excluded by a ruling of the administrative law judge may offer the evidence for the record on appeal. ...
14 CFR 16.231 - Offer of proof.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Offer of proof. 16.231 Section 16.231... PRACTICE FOR FEDERALLY-ASSISTED AIRPORT ENFORCEMENT PROCEEDINGS Hearings § 16.231 Offer of proof. A party whose evidence has been excluded by a ruling of the hearing officer may offer the evidence on the record...
49 CFR 1503.641 - Offer of proof.
2010-10-01
... 49 Transportation 9 2010-10-01 2010-10-01 false Offer of proof. 1503.641 Section 1503.641... Rules of Practice in TSA Civil Penalty Actions § 1503.641 Offer of proof. A party whose evidence has been excluded by a ruling of the ALJ may offer the evidence for the record on appeal. ...
Tree Resolution Proofs of the Weak Pigeon-Hole Principle
DEFF Research Database (Denmark)
Dantchev, Stefan Stajanov; Riis, Søren
2001-01-01
We prove that any optimal tree resolution proof of PHPn m is of size 2&thetas;(n log n), independently from m, even if it is infinity. So far, only a 2Ω(n) lower bound has been known in the general case. We also show that any, not necessarily optimal, regular tree resolution proof PHPn m is bound...
Another proof of Gell-Mann and Low's theorem
Molinari, Luca Guido
2006-01-01
The theorem by Gell-Mann and Low is a cornerstone in QFT and zero-temperature many-body theory. The standard proof is based on Dyson's time-ordered expansion of the propagator; a proof based on exact identities for the time-propagator is here given.
Another proof of Gell-Mann and Low's theorem
International Nuclear Information System (INIS)
Molinari, Luca Guido
2007-01-01
The theorem by Gell-Mann and Low is a cornerstone in quantum field theory and zero-temperature many-body theory. The standard proof is based on Dyson's time-ordered expansion of the propagator; a proof based on exact identities for the time propagator is here given
A new proof of the positive energy theorem
International Nuclear Information System (INIS)
Witten, E.
1981-01-01
A new proof is given of the positive energy theorem of classical general relativity. Also, a new proof is given that there are no asymptotically Euclidean gravitational instantons. (These theorems have been proved previously, by a different method, by Schoen and Yau). The relevance of these results to the stability of Minkowski space is discussed. (orig.)
A proof challenge: multiple alignment and information compression
Wolff, J Gerard
2014-01-01
These notes pose a "proof challenge": a proof, or disproof, of the proposition that "For any given body of information, I, expressed as a one-dimensional sequence of atomic symbols, a multiple alignment concept, described in the document, provides a means of encoding all the redundancy that may exist in I. Aspects of the challenge are described.
34 CFR 34.14 - Burden of proof.
2010-07-01
... 34 Education 1 2010-07-01 2010-07-01 false Burden of proof. 34.14 Section 34.14 Education Office of the Secretary, Department of Education ADMINISTRATIVE WAGE GARNISHMENT § 34.14 Burden of proof. (a... those in § 34.24. (d)(1) If you object on the ground that applicable law bars us from collecting the...
Car sequencing is NP-hard: a short proof
B Estellon; F Gardi
2013-01-01
In this note, a new proof is given that the car sequencing (CS) problem is NP-hard. Established from the Hamiltonian Path problem, the reduction is direct while closing some gaps remaining in the previous NP-hardness results. Since CS is studied in many operational research courses, this result and its proof are particularly interesting for teaching purposes.
Security proof for round robin differential phase shift QKD
Leermakers, D.; Skoric, B.
2017-01-01
We give the first information-theoretic security proof of the `Round Robin Differential Phase Shift' Quantum Key Distribution scheme. Our proof consists of the following steps. We construct an EPR variant of the scheme. We identify Eve's optimal way of coupling an ancilla to an EPR qudit pair under
Values and Norms of Proof for Mathematicians and Students
Dawkins, Paul Christian; Weber, Keith
2017-01-01
In this theoretical paper, we present a framework for conceptualizing proof in terms of mathematical values, as well as the norms that uphold those values. In particular, proofs adhere to the values of establishing a priori truth, employing decontextualized reasoning, increasing mathematical understanding, and maintaining consistent standards for…
Preservice Mathematics Teachers' Metaphorical Perceptions towards Proof and Proving
Ersen, Zeynep Bahar
2016-01-01
Since mathematical proof and proving are in the center of mathematics; preservice mathematics teachers' perceptions against these concepts have a great importance. Therefore, the study aimed to determine preservice mathematics teachers' perceptions towards proof and proving through metaphors. The participants consisted of 192 preservice…
A Calculus of Circular Proofs and its Categorical Semantics
DEFF Research Database (Denmark)
Santocanale, Luigi
2002-01-01
We present a calculus of “circular proofs”: the graph underlying a proof is not a finite tree but instead it is allowed to contain a certain amount of cycles.The main challenge in developing a theory for the calculus is to define the semantics of proofs, since the usual method by induction...
Why prove it again? alternative proofs in mathematical practice
Dawson, Jr , John W
2015-01-01
This monograph considers several well-known mathematical theorems and asks the question, “Why prove it again?” while examining alternative proofs. It explores the different rationales mathematicians may have for pursuing and presenting new proofs of previously established results, as well as how they judge whether two proofs of a given result are different. While a number of books have examined alternative proofs of individual theorems, this is the first that presents comparative case studies of other methods for a variety of different theorems. The author begins by laying out the criteria for distinguishing among proofs and enumerates reasons why new proofs have, for so long, played a prominent role in mathematical practice. He then outlines various purposes that alternative proofs may serve. Each chapter that follows provides a detailed case study of alternative proofs for particular theorems, including the Pythagorean Theorem, the Fundamental Theorem of Arithmetic, Desargues’ Theorem, the...
An Examination of Undefined Forms of Proof in Academic Debate.
Underwood, Willard A.
Although texts on debate and argumentation deal with accepted forms of evidence, reasoning, and logical methods of proof, they do not cover adequately the "undefined" forms of proof. Criteria of evidence found in forensic literature are not always followed strictly by judges, in courtroom or classroom. Many debate judges allow imprecise, vague, or…
Velocity feedback control with a flywheel proof mass actuator
Kras, Aleksander; Gardonio, Paolo
2017-08-01
This paper presents four new proof mass actuators to be used in velocity feedback control systems for the control of vibrations of machines and flexible structures. A classical proof mass actuator is formed by a coil-magnet linear motor, with either the magnet or the armature-coil proof mass suspended on soft springs. This arrangement produces a net force effect at frequencies above the fundamental resonance frequency of the springs-proof mass system. Thus, it can be used to implement point velocity feedback loops, although the dynamic response and static deflection of the springs-proof mass system poses some stability and control performance limitations. The four proof mass actuators presented in this study include a flywheel element, which is used to augment the inertia effect of the suspended proof mass. The paper shows that the flywheel element modifies both the dynamic response and static deflection of the springs-proof mass system in such a way as the stability and control performance of velocity feedback loops using these actuators are significantly improved.
A correctness proof of the bakery protocol in $ mu $CRL
J.F. Groote (Jan Friso); H.P. Korver
1994-01-01
textabstractA specification of a bakery protocol is given in $mu$CRL. We provide a simple correctness criterion for the protocol. Then the protocol is proven correct using a proof system that has been developed for $mu$CRL. The proof primarily consists of algebraic manipulations based on
Three Styles Characterising Mathematicians' Pedagogical Perspectives on Proof
Hemmi, Kirsti
2010-01-01
The article describes mathematicians' pedagogical perspectives on proof in the teaching of first year university students at a mathematics department in Sweden. A conceptual frame that was used in the data analysis combines theories about proof from earlier mathematics education research with a social practice approach of Lave and Wenger. A…
The bounded proof property via step algebras and step frames
Bezhanishvili, N.; Ghilardi, Silvio
2013-01-01
We develop a semantic criterion for a specific rule-based calculus Ax axiomatizing a given logic L to have the so-called bounded proof property. This property is a kind of an analytic subformula property limiting the proof search space. Our main tools are one-step frames and one-step algebras. These
14 CFR 25.307 - Proof of structure.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Proof of structure. 25.307 Section 25.307... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure General § 25.307 Proof of structure. (a) Compliance with... condition. Structural analysis may be used only if the structure conforms to that for which experience has...
A compositional proof system for the modal μ-calculus
DEFF Research Database (Denmark)
Andersen, Henrik Reif; Stirling, C.; Winskel,, G.
1994-01-01
We present a proof system for determining satisfaction between processes in a fairly general process algebra and assertions of the modal μ-calculus. The proof system is compositional in the structure of processes. It extends earlier work on compositional reasoning within the modal μ-calculus and ...
International Nuclear Information System (INIS)
Poirier, J.; Barbe, B.; Jolly, N.
1976-01-01
The aim is to show how internal stresses are generated and to fix the orders of magnitude. A realistic case, the vertical welding of thick plates free to move one against the other, is described and the deformations and stresses are analyzed. The mathematical model UEDA, which accounts for the elastic modulus, the yield strength and the expansion coefficient of the metal with temperature, is presented. The hypotheses and results given apply only to the instantaneous welding of a welded plate and to a plate welded by a moving electrode [fr
DEFF Research Database (Denmark)
Pedersen, Niels Leergaard
2013-01-01
The state of stress in bolts and nuts with ISO metric thread design is examined and optimized. The assumed failure mode is fatigue so the applied preload and the load amplitude together with the stress concentrations define the connection strength. Maximum stress in the bolt is found at, the fillet...... under the head, at the thread start or at the thread root. To minimize the stress concentration shape optimization is applied....
International Nuclear Information System (INIS)
Halliwell, J.J.
2014-01-01
Fine's theorem concerns the question of determining the conditions under which a certain set of probabilities for pairs of four bivalent quantities may be taken to be the marginals of an underlying probability distribution. The eight CHSH inequalities are well-known to be necessary conditions, but Fine's theorem is the striking result that they are also sufficient conditions. Here two transparent and self-contained proofs of Fine's theorem are presented. The first is a physically motivated proof using an explicit local hidden variables model. The second is an algebraic proof which uses a representation of the probabilities in terms of correlation functions. - Highlights: • A discussion of the various approaches to proving Fine's theorem. • A new physically-motivated proof using a local hidden variables model. • A new algebraic proof. • A new form of the CHSH inequalities
ORION - Crew Module Side Hatch: Proof Pressure Test Anomaly Investigation
Evernden, Brent A.; Guzman, Oscar J.
2018-01-01
The Orion Multi-Purpose Crew Vehicle program was performing a proof pressure test on an engineering development unit (EDU) of the Orion Crew Module Side Hatch (CMSH) assembly. The purpose of the proof test was to demonstrate structural capability, with margin, at 1.5 times the maximum design pressure, before integrating the CMSH to the Orion Crew Module structural test article for subsequent pressure testing. The pressure test was performed at lower pressures of 3 psig, 10 psig and 15.75 psig with no apparent abnormal behavior or leaking. During pressurization to proof pressure of 23.32 psig, a loud 'pop' was heard at 21.3 psig. Upon review into the test cell, it was noted that the hatch had prematurely separated from the proof test fixture, thus immediately ending the test. The proof pressure test was expected be a simple verification but has since evolved into a significant joint failure investigation from both Lockheed Martin and NASA.
DEFF Research Database (Denmark)
Ledertoug, Mette Marie
-being. The Ph.D.-project in Strength-based learning took place in a Danish school with 750 pupils age 6-16 and a similar school was functioning as a control group. The presentation will focus on both the aware-explore-apply processes and the practical implications for the schools involved, and on measurable......Strength-based learning - Children͛s Character Strengths as Means to their Learning Potential͛ is a Ph.D.-project aiming to create a strength-based mindset in school settings and at the same time introducing strength-based interventions as specific tools to improve both learning and well...
Integrating PROOF Analysis in Cloud and Batch Clusters
International Nuclear Information System (INIS)
Rodríguez-Marrero, Ana Y; Fernández-del-Castillo, Enol; López García, Álvaro; Marco de Lucas, Jesús; Matorras Weinig, Francisco; González Caballero, Isidro; Cuesta Noriega, Alberto
2012-01-01
High Energy Physics (HEP) analysis are becoming more complex and demanding due to the large amount of data collected by the current experiments. The Parallel ROOT Facility (PROOF) provides researchers with an interactive tool to speed up the analysis of huge volumes of data by exploiting parallel processing on both multicore machines and computing clusters. The typical PROOF deployment scenario is a permanent set of cores configured to run the PROOF daemons. However, this approach is incapable of adapting to the dynamic nature of interactive usage. Several initiatives seek to improve the use of computing resources by integrating PROOF with a batch system, such as Proof on Demand (PoD) or PROOF Cluster. These solutions are currently in production at Universidad de Oviedo and IFCA and are positively evaluated by users. Although they are able to adapt to the computing needs of users, they must comply with the specific configuration, OS and software installed at the batch nodes. Furthermore, they share the machines with other workloads, which may cause disruptions in the interactive service for users. These limitations make PROOF a typical use-case for cloud computing. In this work we take profit from Cloud Infrastructure at IFCA in order to provide a dynamic PROOF environment where users can control the software configuration of the machines. The Proof Analysis Framework (PAF) facilitates the development of new analysis and offers a transparent access to PROOF resources. Several performance measurements are presented for the different scenarios (PoD, SGE and Cloud), showing a speed improvement closely correlated with the number of cores used.
Measurement of components of load parallel to cracks in a proof of safety against fracture
International Nuclear Information System (INIS)
Amstutz, H.; Seeger, T.
1992-01-01
Largely standardized processes are now available in the R6 concept, the engineering approach and the engineering treatment model (ETM) according to Schwalbe, which make judgment and quantitative assessment of the fracture and failure behaviour of components with cracks and faults similar to cracks possible. When using the process on components with a multi-axial basic stress state, the question arises for pure mode I stresses, to what extent and in what form the effect of the load parallel to the cracks can be included in the concepts. Based on a numerical study with finite elements, the connections between global bi-axial load and local stress conditions are shown in the article, using the example of the J integral, and are discussed regarding taken them into account in the proof of safety against fracture. (orig.) [de
Yavorskiy, R.
Kripke-style semantics is suggested for the provability logic with quantifiers on proofs corresponding to the standard Gödel proof predicate. It is proved that the set of valid formulas is decidable. The arithmetical completeness is still an open issue.
2010-07-01
... participated onsite in the atmospheric detonation of a nuclear device. ... requisite period and proof of participation onsite during a period of atmospheric nuclear testing. 79.13... presence for the requisite period and proof of participation onsite during a period of atmospheric nuclear...
Slippage of steel in high and normal strength concrete
International Nuclear Information System (INIS)
Ahmed, K.; Siddiqi, Z.A.; Yousaf, M.
2007-01-01
Composite action of any reinforced concrete member is only possible if sufficient bond strength exists between steel reinforcing bars and concrete, which can adequately transfer shear stress between them. Bond strength is a function of compressive strength of concrete and hence high strength concrete has higher bond strength (1-2). Therefore required development length can be reduced. In order to investigate the effect of development length on bond stress and slip relationships, experimental investigation was carried out. In this experimentation 24 pull-out samples of high strength concrete and normal strength concrete were casted and tested. The results of this investigation revealed that by increasing the development length from 5db to 10db bond strength increases for both high and normal strength concrete as shown in Figure 11, 12 and 13. However in case of normal strength concrete increase in bond strength is more compared to that in high strength concrete as it is clear from Figure 11 and Figure 13. The increase in bond strength is observed even at 10db development length but the extent is less for 19 mm than 16 mm bars as shown in Figure 12 and Figure 13. This is in agreement with the earlier findings of Chen et al (3) and Harajli et al (1). However in case of HSC the total slippage at 10db is 50% greater than at 5db. This may be due to the fact that more no of concrete keys participate in resisting the slippage. (author)
International Nuclear Information System (INIS)
Pinto, N.P.; Keith, G.H.
1977-01-01
Beryllium billets hot isopressed using fine powder of high purity have exceptionally attractive properties; average tensile ultimate, 0.2% offset yield strength and elongation are 590 MPa, 430 MPa and 4.0% respectively. Properties are attributed to the fine grain size (about 4.0 μm average diameter) and the relatively low levels of BeO present as fine, well-dispersed particles. Dynamic properties, e.g., fracture toughness, are similar to those of standard grade, high-purity beryllium. The modulus of beryllium is retained to very high stress levels, and the microyield stress or precision elastic limit is higher than for other grades, including instrument grades. Limited data for billets made from normal-purity fine powders show similar room temperature properties. (author)
Proof of the Wave Nature of Plants
Wagner, Orvin
2008-03-01
I assume plants operate with a set of frequencies. These frequencies and the means of these frequencies are equal in all directions. We can then write (vh/λ)avh=(vv/λ)avv where the subscripts h and v represent horizontal and vertical respectively and av is average,. or vv/vh=(1/λh)av/(1/λv)av. I use an internodal spacing as λ/2 or the the distance between adjacent branches, leaves, etc. The ratios, vv/vh, are ratios of small integers for sufficient samplings. For example, for Ponderosa pine the ratio is 3/1 or for delicious apple 4/3. Note that these ratios represent the shape of the tree or other plant and their interactions with gravity. These ratios are derivable by other means such as use the ratio of # of horizontal needles per unit length from a horizontal sample to the # of needles per unit length from a vertical sample from p-pine. Or measure the vertical and horizontal velocities. My literature provides many other proofs of the wave nature of plants. I suggest that the waves in and related waves outside of plants (outside 4.9 m/s) are a dark matter related since they travel at such low velocities. See my present web site at home.budget.net/˜oedphd.
Natural tuning: towards a proof of concept
Dubovsky, Sergei; Gorbenko, Victor; Mirbabayi, Mehrdad
2013-09-01
The cosmological constant problem and the absence of new natural physics at the electroweak scale, if confirmed by the LHC, may either indicate that the nature is fine-tuned or that a refined notion of naturalness is required. We construct a family of toy UV complete quantum theories providing a proof of concept for the second possibility. Low energy physics is described by a tuned effective field theory, which exhibits relevant interactions not protected by any symmetries and separated by an arbitrary large mass gap from the new "gravitational" physics, represented by a set of irrelevant operators. Nevertheless, the only available language to describe dynamics at all energy scales does not require any fine-tuning. The interesting novel feature of this construction is that UV physics is not described by a fixed point, but rather exhibits asymptotic fragility. Observation of additional unprotected scalars at the LHC would be a smoking gun for this scenario. Natural tuning also favors TeV scale unification.
Duan's fixed point theorem: Proof and generalization
Directory of Open Access Journals (Sweden)
Martin Arkowitz
2006-02-01
Full Text Available Let X be an H-space of the homotopy type of a connected, finite CW-complex, f:XÃ¢Â†Â’X any map and pk:XÃ¢Â†Â’X the kth power map. Duan proved that pkf:XÃ¢Â†Â’X has a fixed point if kÃ¢Â‰Â¥2. We give a new, short and elementary proof of this. We then use rational homotopy to generalize to spaces X whose rational cohomology is the tensor product of an exterior algebra on odd dimensional generators with the tensor product of truncated polynomial algebras on even dimensional generators. The role of the power map is played by a ÃŽÂ¸-structure ÃŽÂ¼ÃŽÂ¸:XÃ¢Â†Â’X as defined by Hemmi-Morisugi-Ooshima. The conclusion is that ÃŽÂ¼ÃŽÂ¸f and fÃŽÂ¼ÃŽÂ¸ each has a fixed point.
Tritium proof-of-principle pellet injector
International Nuclear Information System (INIS)
Fisher, P.W.
1991-07-01
The tritium proof-of-principle (TPOP) experiment was designed and built by Oak Ridge National Laboratory (ORNL) to demonstrate the formation and acceleration of the world's first tritium pellets for fueling of future fusion reactors. The experiment was first used to produce hydrogen and deuterium pellets at ORNL. It was then moved to the Tritium Systems Test Assembly at Los Alamos National Laboratory for the production of tritium pellets. The injector used in situ condensation to produce cylindrical pellets in a 1-m-long, 4-mm-ID barrel. A cryogenic 3 He separator, which was an integral part of the gun assembly, was capable of lowering 3 He levels in the feed gas to <0.005%. The experiment was housed to a glovebox for tritium containment. Nearly 1500 pellets were produced during the course of the experiment, and about a third of these were pure tritium or mixtures of deuterium and tritium. Over 100 kCi of tritium was processed through the experiment without incident. Tritium pellet velocities of 1400 m/s were achieved with high-pressure hydrogen propellant. The design, operation, and results of this experiment are summarized. 34 refs., 44 figs., 3 tabs
Fatigue strength of socket welded pipe joint
International Nuclear Information System (INIS)
Iida, K.; Matsuda, F.; Sato, M.; Higuchi, M.; Nakagawa, A.
1994-01-01
Fully reversed four point bending fatigue tests were carried out of small diameter socket welded joints made of carbon steels. Experimental parameters are pipe diameter, thickness of pipe and socket wall, throat depth and shape of fillet welds, slip-on and diametral gaps in the socket welding, lack of penetration at the root of fillet welds, and peening of fillet welds. In most cases a fatigue crack started from the root of the fillet, but in the case of higher stress amplitude, it tended to start from the toe of fillet. The standard socket welded joint of 50 mm diameter showed relatively low fatigue strength, 46 MPa in stress amplitude at the 10 7 cycles failure life. This value corresponds to about 1/5 of that of the smoothed base metal specimens in axial fatigue. The fatigue strength showed decrease with increasing pipe diameter, and increase with increasing the thickness of pipe and socket wall. The effects of throat depth and shape of fillet welds on fatigue strength were not significant. Contrary to the expectation, the fatigue strength of the socket welded joint without slip-on gap is higher than that of the joint with the normal gap. A lack of penetration at the root deleteriously reduced fatigue strength, showing 14 MPa in stress amplitude at the 10 7 cycles failure life for the 50 mm diameter socket joint. (orig.)
Autonomous intelligent cars: proof that the EPSRC Principles are future-proof
de Cock Buning, Madeleine; de Bruin, Roeland
2017-07-01
Principle 2 of the EPSRC's principles of robotics (AISB workshop on Principles of Robotics, 2016) proves to be future proof when applied to the current state of the art of law and technology surrounding autonomous intelligent cars (AICs). Humans, not AICS, are responsible agents. AICs should be designed; operated as far as is practicable to comply with existing laws and fundamental rights and freedoms, including privacy by design. It will show that some legal questions arising from autonomous intelligent driving technology can be answered by the technology itself.
Visual Considerations in the Presentation of Mathematical Proofs
Directory of Open Access Journals (Sweden)
Lara Alcock
2010-11-01
Full Text Available This article is about visual issues in the presentation of mathematics within teaching situations. It focuses particularly on the presentation of proofs to undergraduate students. We describe some of the decisions that a lecturer must make when presenting a written proof, from the layout of individual equations to the layout of a whole argument on the page. We consider the way in which these decisions are made explicit for lecturers who construct electronic learning resources termed e-Proofs, and conclude by discussing the constraints and affordances of this technology.
Institute of Scientific and Technical Information of China (English)
维拉
1996-01-01
Mort had an absolutely terrible day at the office.Everythingthat could go wrong did go wrong.As he walked home he could beheard muttering strange words to himself:“Oh,give me strength,give me strength.”Mort isn’t asking for the kind of strength thatbuilds strong muscles:he’s asking for the courage or ability to
Creep Strength of Discontinuous Fibre Composites
DEFF Research Database (Denmark)
Pedersen, Ole Bøcker
1974-01-01
relation between stress and strain rate. Expressions for the interface stress, the creep velocity profile adjacent to the fibres and the creep strength of the composite are derived. Previous results for the creep strength, sc = aVfs0 ( \\frac[( Î )\\dot] [( Î )\\dot] 0 )1/nr1 + 1/n c=Vf001n1+1n in which[( Î...... )\\dot] is the composite creep rate,V f is the fibre volume fraction,sgr 0,epsi 0 andn are the constants in the matrix creep law. The creep strength coefficient agr is found to be very weakly dependent onV f and practically independent ofn whenn is greater than about 6....
von Carlowitz-Ghori, K; Bayraktaroglu, Z; Waterstraat, G; Curio, G; Nikulin, V V
2015-04-02
Corticomuscular coherence (CMC) relates to synchronization between activity in the motor cortex and the muscle activity. The strength of CMC can be affected by motor behavior. In a proof-of-principle study, we examined whether independent of motor output parameters, healthy subjects are able to voluntarily modulate CMC in a neurofeedback paradigm. Subjects received visual online feedback of their instantaneous CMC strength, which was calculated between an optimized spatial projection of multichannel electroencephalography (EEG) and electromyography (EMG) in an individually defined target frequency range. The neurofeedback training consisted of either increasing or decreasing CMC strength using a self-chosen mental strategy while performing a simple motor task. Evaluation of instantaneous coherence showed that CMC strength was significantly larger when subjects had to increase than when to decrease CMC; this difference between the two task conditions did not depend on motor performance. The exclusion of confounding factors such as motor performance, attention and task complexity in study design provides evidence that subjects were able to voluntarily modify CMC independent of motor output parameters. Additional analysis further strengthened the assumption that the subjects' response was specifically shaped by the neurofeedback. In perspective, we suggest that CMC-based neurofeedback could provide a therapeutic approach in clinical conditions, such as motor stroke, where CMC is altered. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.
Is your automated system disaster proof?
International Nuclear Information System (INIS)
Baird, P.W.; Priest, S.A.
1990-01-01
Disaster-proofing a system has four basic steps: (1) development of a disaster recovery plan; (2) creation and enforcement of procedures for developing and maintaining off-site back-ups for data, vital records, and documentation; (3) a performance test of the disaster recovery plan; and (4) the on-going maintenance of a plans currency and the periodic testing of the plant. The development of a complete disaster recovery plan has many elements: the operating environment for the system; the criteria under which an off-site recovery would be initiated; the back-up schedule and locations of all data; vital records and documentation; the steps required to recover the system; and any modifications necessitated by the off-site operating environment. Creation and enforcement of procedures for developing and maintaining current backups for all data, vital records, and documentation in a designated off-site location represent the second and most crucial step for ensuring an automated system can successfully survive a disaster. To effectively test any plan, a disaster scenario must be developed and performed by a disaster recovery team required to recover and operate the system in the off-site environment using nothing more than the disaster recovery plan and off-site information and data. Finally, the last step for ensuring that a system can survive a disaster is the maintenance of the plans currency and the continued performance of disaster recovery tests. As the environment surrounding a system changes a disaster recovery plan must be updated to reflect these changes. Equally important to the maintenance of currency is the on-going performance of disaster recovery tests on a periodic basis
Skolem and pessimism about proof in mathematics.
Cohen, Paul J
2005-10-15
Attitudes towards formalization and proof have gone through large swings during the last 150 years. We sketch the development from Frege's first formalization, to the debates over intuitionism and other schools, through Hilbert's program and the decisive blow of the Gödel Incompleteness Theorem. A critical role is played by the Skolem-Lowenheim Theorem, which showed that no first-order axiom system can characterize a unique infinite model. Skolem himself regarded this as a body blow to the belief that mathematics can be reliably founded only on formal axiomatic systems. In a remarkably prescient paper, he even sketches the possibility of interesting new models for set theory itself, something later realized by the method of forcing. This is in contrast to Hilbert's belief that mathematics could resolve all its questions. We discuss the role of new axioms for set theory, questions in set theory itself, and their relevance for number theory. We then look in detail at what the methods of the predicate calculus, i.e. mathematical reasoning, really entail. The conclusion is that there is no reasonable basis for Hilbert's assumption. The vast majority of questions even in elementary number theory, of reasonable complexity, are beyond the reach of any such reasoning. Of course this cannot be proved and we present only plausibility arguments. The great success of mathematics comes from considering 'natural problems', those which are related to previous work and offer a good chance of being solved. The great glories of human reasoning, beginning with the Greek discovery of geometry, are in no way diminished by this pessimistic view. We end by wishing good health to present-day mathematics and the mathematics of many centuries to come.
Strength and lifetime of polymer glasses
Energy Technology Data Exchange (ETDEWEB)
Bartenev, G.M.; Kartasov, E.M.
1981-03-01
A kinetic equation of the time-dependence of strength (complete isotherm of lifetime) of polymer glasses at stress values ranging from the limiting stress of the occurence of separation breaks to the critical stress is derived. The curvature of lifetime plots occuring at low and high periods of time in the experiments are considered. The ranges of noncritical state, breaks caused by a thermofluctuation mechanism, a transition range and athermal breaks are discerned. The limitations of applicability of the basic empirical equation of the kinetic theory of the time-dependence of strength are explained. Theoretical equations are suggested for calculating various characteristics of the brittle break, as limiting stress and critical stress, relative critical craze length and coefficient of stress concentration at the craze tip with respect to various geometrical configurations of the craze and its position in the sample. With polymethylmethacrylate as an example in the brittle and quasi-brittle state, as characterized by the transition from the rupture of sets of chemical bonds to individual chemical bonds, the thermofluctuation processes of break in polymer glasses are discussed. The application of the thermofluctuation theory of solids to the quasi-brittle fracture is considered. The growth kinetics of crazes and the corresponding equation of lifetime were found to be described by identical (corresponding) analytical expressions by which the changes of the coefficients of stress concentration in the range of microplastic deformation in front of the growing is covered within a wide region of temperature including the brittle temperature.
Ultimate Strength of Ship Hulls under Torsion
DEFF Research Database (Denmark)
Paik, Jeom Kee; Thayamballi, Anil K.; Pedersen, Preben Terndrup
2001-01-01
For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening deformations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength characte......For a ship hull with large deck openings such as container vessels and some large bulk carriers, the analysis of warping stresses and hatch opening deformations is an essential part of ship structural analyses. It is thus of importance to better understand the ultimate torsional strength...... characteristics of ships with large hatch openings. The primary aim of the present study is to investigate the ultimate strength characteristics of ship hulls with large hatch openings under torsion. Axial (warping) as well as shear stresses are normally developed for thin-walled beams with open cross sections...... subjected to torsion. A procedure for calculating these stresses is briefly described. As an illustrative example, the distribution and magnitude of warping and shear stresses for a typical container vessel hull cross section under unit torsion is calculated by the procedure. By theoretical and numerical...
A nonperturbative proof of Dijkgraaf-Vafa conjecture
International Nuclear Information System (INIS)
Terashima, Seiji
2016-01-01
In this note we exactly compute the gaugino condensation of an arbitrary four dimensional N=1 supersymmetric gauge theory in confining phase, using the localization technique. This result gives a nonperturbative proof of the Dijkgraaf-Vafa conjecture.
27 CFR 19.277 - Measuring devices and proofing instruments.
2010-04-01
... proof or volume. (b) Instruments. Hydrometers and thermometers used by proprietors to gauge spirits... made in conjunction with the volumetric measurement of spirits by meter. If a meter does not have a...
The quadratic reciprocity law a collection of classical proofs
Baumgart, Oswald
2015-01-01
This book is the English translation of Baumgart’s thesis on the early proofs of the quadratic reciprocity law (“Über das quadratische Reciprocitätsgesetz. Eine vergleichende Darstellung der Beweise”), first published in 1885. It is divided into two parts. The first part presents a very brief history of the development of number theory up to Legendre, as well as detailed descriptions of several early proofs of the quadratic reciprocity law. The second part highlights Baumgart’s comparisons of the principles behind these proofs. A current list of all known proofs of the quadratic reciprocity law, with complete references, is provided in the appendix. This book will appeal to all readers interested in elementary number theory and the history of number theory.
A Simple Proof of Cauchy's Surface Area Formula
Tsukerman, Emmanuel; Veomett, Ellen
2016-01-01
We give a short and simple proof of Cauchy's surface area formula, which states that the average area of a projection of a convex body is equal to its surface area up to a multiplicative constant in the dimension.
A Coordinate-Based Proof of the Scallop Theorem
Ishimoto, Kenta; Yamada, Michio
2012-01-01
We reconsider fluid dynamics for a self-propulsive swimmer in Stokes flow. With an exact definition of deformation of a swimmer, a coordinate-based proof is first given to Purcell's scallop theorem including the body rotation.
Construction of state-independent proofs for quantum contextuality
Tang, Weidong; Yu, Sixia
2017-12-01
Since the enlightening proofs of quantum contextuality first established by Kochen and Specker, and also by Bell, various simplified proofs have been constructed to exclude the noncontextual hidden variable theory of our nature at the microscopic scale. The conflict between the noncontextual hidden variable theory and quantum mechanics is commonly revealed by Kochen-Specker sets of yes-no tests, represented by projectors (or rays), via either logical contradictions or noncontextuality inequalities in a state-(in)dependent manner. Here we propose a systematic and programmable construction of a state-independent proof from a given set of nonspecific rays in C3 according to their Gram matrix. This approach brings us a greater convenience in the experimental arrangements. Besides, our proofs in C3 can also be generalized to any higher-dimensional systems by a recursive method.
The Standard of Proof in Criminal Proceedings: the Threshold to ...
African Journals Online (AJOL)
Hanna_AZ
The standard of proof, along with other basic notions in the law of evidence, ... testimony. Among the different theories and formulations surrounding the beyond a .... rule, the prosecution are obliged (i) to prove that the accused committed the.
27 CFR 30.32 - Determination of proof obscuration.
2010-04-01
... added to the temperature corrected hydrometer reading will give the true proof. (c) Distillation method... use of a precision hydrometer and thermometer in accordance with the provisions of § 13.23 to the...
Circular, explosion-proof lamp provides uniform illumination
1966-01-01
Circular explosion-proof fluorescent lamp is fitted around a TV camera lens to provide shadowless illumination with a low radiant heat flux. The lamp is mounted in a transparent acrylic housing sealed with clear silicone rubber.
Litigation-proof patents: avoiding the most common patent mistakes
National Research Council Canada - National Science Library
Goldstein, Larry M
2014-01-01
"Litigation-Proof Patents: Avoiding the Most Common Patent Mistakes explains the principles of excellent patents, presents the ten most common errors in patents, and details a step-by-step method for avoiding these common errors...
An Elementary Proof of the Polynomial Matrix Spectral Factorization Theorem
Ephremidze, Lasha
2010-01-01
A very simple and short proof of the polynomial matrix spectral factorization theorem (on the unit circle as well as on the real line) is presented, which relies on elementary complex analysis and linear algebra.
Logic Reduced To Bare (Proof-Theoretical) Bones
Czech Academy of Sciences Publication Activity Database
Peregrin, Jaroslav
2015-01-01
Roč. 24, č. 2 (2015), s. 193-209 ISSN 0925-8531 Institutional support: RVO:67985955 Keywords : inference * incompatibility * proof theory * intuitionistic logic Subject RIV: AA - Philosophy ; Religion Impact factor: 0.450, year: 2015
Yield strength of attached copper film
International Nuclear Information System (INIS)
Zhang Yan; Zhang Jian-Min
2011-01-01
Variation of stress in attached copper film with an applied strain is measured by X-ray diffraction combined with a four-point bending method. A lower slope of the initial elastic segment of the curve of X-ray measured stress versus applied strain results from incomplete elastic strain transferred from the substrate to the film due to insufficiently strong interface cohesion. So the slope of the initial elastic segment of the X-ray stress (or X-ray strain directly) of the film against the substrate applied strain may be used to measure the film-substrate cohesive strength. The yield strength of the attached copper film is much higher than that of the bulk material and varies linearly with the inverse of the film thickness. (condensed matter: structural, mechanical, and thermal properties)
On the burden of proof in civil procedure
Directory of Open Access Journals (Sweden)
Keča Ranko
2013-01-01
Full Text Available The appliance of burden of proof rules is conceived of assumption that evidences are taken and that court didn't reach the required degree of conviction of a particular fact, what implies limitation of application of these rules on proceedings in which the judgment is rendered after the plenary proceedings. The Code of Civil Procedure (CCP has no suitable answers for the problems arising from new conception of the principle of party control of facts and means of proof in Serbian litigation legislature, by which the court has no more power to take the evidence ex offo. There is no answer to the question how should court conduct when evidence is not taken because of a lack of parties' indication of the means of proof. In this case courts practice somehow wider conception of burden of proof rules, which however has no explicit legal ground. They are applying them even though evidences are not taken. In any case it would be useful to reformulate basic rule of burden of proof in manner which would correspondent to the new conception of the principle of party presentation. The rule of burden of proof applies when the high degree of conviction of facts is demanded from the court, in order to render the judgment. Consequently this rule loses its' sense when mere probability of factual findings is demanded. The broader conception of parties' representation principle however does not liberate court from his responsibility to clarify facts that should be base for adjudication. Circumstance that CCP does mention the principle of material truth anymore should not be seen as argument for liberation of mentioned responsibility. It is still expected from the court to be active. Only when joint effort of the court and parties is left without of goal, in sense that court doesn't reach the high degree conviction, there would be ground for burden of proof rule's application. In this situation court also must justify why he couldn't reach required degree of
Finite Element Simulation of Diametral Strength Test of Hydroxyapatite
International Nuclear Information System (INIS)
Ozturk, Fahrettin; Toros, Serkan; Evis, Zafer
2011-01-01
In this study, the diametral strength test of sintered hydroxyapatite was simulated by the finite element software, ABAQUS/Standard. Stress distributions on diametral test sample were determined. The effect of sintering temperature on stress distribution of hydroxyapatite was studied. It was concluded that high sintering temperatures did not reduce the stress on hydroxyapatite. It had a negative effect on stress distribution of hydroxyapatite after 1300 deg. C. In addition to the porosity, other factors (sintering temperature, presence of phases and the degree of crystallinity) affect the diametral strength of the hydroxyapatite.
A short list color proof of Grotzsch's theorem
DEFF Research Database (Denmark)
Thomassen, Carsten
2000-01-01
We give a short proof of the result that every planar graph of girth $5$is $3$-choosable and hence also of Gr\\"{o}tzsch's theorem saying that everyplanar triangle-free graph is $3$-colorable.......We give a short proof of the result that every planar graph of girth $5$is $3$-choosable and hence also of Gr\\"{o}tzsch's theorem saying that everyplanar triangle-free graph is $3$-colorable....
Coqoon - An IDE for Interactive Proof Development in Coq
Faithfull, Alexander; Bengtson, Jesper; Tassi, Enrico
2016-01-01
User interfaces for interactive proof assistants have always lagged behind those for mainstream programming languages. Whereas integrated development environments—IDEs—have support for features like project management, version control, dependency analysis and incremental project compilation, “IDE”s for proof assistants typically only operate on files in isolation, relying on external tools to integrate those files into larger projects. In this paper we present Coqoon, an IDE for Coq developme...
Evaluation of predator-proof fenced biodiversity projects
Doelle, Sebastian
2012-01-01
There has been recent debate over the role of predator-proof fences in the management of New Zealand’s biodiversity. The debate has arisen due to concern that investments in fenced sanctuaries are less productive than are alternative ways to manage biodiversity. Predator-proof fences are costly and budget constraints limit the area of habitat that can be fenced. The area of habitat enclosed within fences, and number of individuals of species supported, determines project’s ability to contribu...
Structuring Interactive Correctness Proofs by Formalizing Coding Idioms
Gast, Holger
2012-01-01
This paper examines a novel strategy for developing correctness proofs in interactive software verification for C programs. Rather than proceeding backwards from the generated verification conditions, we start by developing a library of the employed data structures and related coding idioms. The application of that library then leads to correctness proofs that reflect informal arguments about the idioms. We apply this strategy to the low-level memory allocator of the L4 microkernel, a case st...
Reversal burden of proof on corruption in Indonesia
Nugroho, Hibnu
2018-01-01
Corruption becomes the greatest enemy most countries face including Indonesia. Commitment to eradicate corruption significantly increases yet it would be meaningless if it is not supported by adequate legislation to implement the law effectively. Reversal burden of proof essentially aims to facilitate law enforcers to seek and disclose assets a suspect owns allegedly as corruption crime. The principle of reversal burden of proof was originated from Anglo-Saxon countries and this still applies...
Anisotropic Concrete Compressive Strength
DEFF Research Database (Denmark)
Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao
2017-01-01
When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...
International Nuclear Information System (INIS)
1977-01-01
A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)
International Nuclear Information System (INIS)
Bergqvist, I.
1976-01-01
Methods for extracting photon strength functions are briefly discussed. We follow the Brink-Axel approach to relate the strength functions to the giant resonances observed in photonuclear work and summarize the available data on the E1, E2 and M1 resonances. Some experimental and theoretical problems are outlined. (author)
Interviewing to Understand Strengths
Hass, Michael R.
2018-01-01
Interviewing clients about their strengths is an important part of developing a complete understanding of their lives and has several advantages over simply focusing on problems and pathology. Prerequisites for skillfully interviewing for strengths include the communication skills that emerge from a stance of not knowing, developing a vocabulary…
Overall bolt stress optimization
DEFF Research Database (Denmark)
Pedersen, Niels Leergaard
2013-01-01
The state of stress in bolts and nuts with International Organization for Standardization metric thread design is examined and optimized. The assumed failure mode is fatigue, so the applied preload and the load amplitude together with the stress concentrations define the connection strength....... Maximum stress in the bolt is found at the fillet under the head, at the thread start, or at the thread root. To minimize the stress concentration, shape optimization is applied. Nut shape optimization also has a positive effect on the maximum stress. The optimization results show that designing a nut......, which results in a more evenly distribution of load along the engaged thread, has a limited influence on the maximum stress due to the stress concentration at the first thread root. To further reduce the maximum stress, the transition from bolt shank to the thread must be optimized. Stress reduction...
Analysis of bone mineral density of human bones for strength ...
Indian Academy of Sciences (India)
Different types of bone strength are required for various ... To statically analyse various methods to find BMD and related material ... bone study for research purpose. ..... and Dagoberto Vela Arvizo 2007 A qualitative stress analysis of a cross ...
Earthquake proof device for nuclear power plant building
International Nuclear Information System (INIS)
Okada, Yasuo.
1991-01-01
The structure of the present invention enables three dimensional vibration proof, i.e., in horizontal and vertical directions of a reactor container building. That is, each of the reactor container building and a reactor auxiliary building is adapted as an independent structure. The periphery of the reactor container building is surrounded by the reactor auxiliary building. The reactor auxiliary building is supported against the ground by way of a horizontal vibration proof device. The reactor container building is supported against the ground by way of a three-dimensional vibration proof device that prevents vibrations in both of the horizontal directions, and the vertical directions. The reactor container building is connected to the auxiliary building by way of a vertical vibration proof device. With such a constitution, although the reactor container building is vibration proof against both of the horizontal and the vertical vibrations, the vertical vibration proofness is an extension of inherent vertical vibration period. Accordingly, the head of the building undergoes rocking vibrations. However, since the reactor container building is connected to the reactor auxiliary building, the rocking vibrations are prevented by the reactor auxiliary building. As a result, safety upon occurrence of an earthquakes can be ensured. (I.S.)
Proof Pad: A New Development Environment for ACL2
Directory of Open Access Journals (Sweden)
Caleb Eggensperger
2013-04-01
Full Text Available Most software development projects rely on Integrated Development Environments (IDEs based on the desktop paradigm, with an interactive, mouse-driven user interface. The standard installation of ACL2, on the other hand, is designed to work closely with Emacs. ACL2 experts, on the whole, like this mode of operation, but students and other new programmers who have learned to program with desktop IDEs often react negatively to the process of adapting to an unfamiliar form of interaction. This paper discusses Proof Pad, a new IDE for ACL2. Proof Pad is not the only attempt to provide ACL2 IDEs catering to students and beginning programmers. The ACL2 Sedan and DrACuLa systems arose from similar motivations. Proof Pad builds on the work of those systems, while also taking into account the unique workflow of the ACL2 theorem proving system. The design of Proof Pad incorporated user feedback from the outset, and that process continued through all stages of development. Feedback took the form of direct observation of users interacting with the IDE as well as questionnaires completed by users of Proof Pad and other ACL2 IDEs. The result is a streamlined interface and fast, responsive system that supports using ACL2 as a programming language and a theorem proving system. Proof Pad also provides a property-based testing environment with random data generation and automated interpretation of properties as ACL2 theorem definitions.
DEFF Research Database (Denmark)
Burcharth, Hans F.; Liu, Zhou; Howell, Gary L.
1991-01-01
Failures of rubble mound breakwaters armoured with complex types of unreinforced concrete armour units are often due to breakage. This happens when the stresses exceed the material strength. Sufficient parametric studies of the stresses are not yet available to produce design diagrams for structu......Failures of rubble mound breakwaters armoured with complex types of unreinforced concrete armour units are often due to breakage. This happens when the stresses exceed the material strength. Sufficient parametric studies of the stresses are not yet available to produce design diagrams...... for structural integrity. The paper presents the results and the analyses of model tests with 200 kg and 200 g load-cell instrumented Dolosse. Static stresses and wave generated stresses were studied as well as model and scale effects. A preliminary design diagram for Dolosse is presented as well....
International Nuclear Information System (INIS)
Wang, R L; Gu, H; Song, G; Mo, Y L
2013-01-01
This paper presents a proof-of-concept experimental study of an innovative active-sensing approach for damage detection of concrete piles by using embedded piezoceramic transducers. In the proposed active-sensing approach, one piezoceramic transducer is used as an actuator to generate a stress wave to propagate through the concrete pile and the other distributed piezoceramic transducers are used as sensors to detect the wave response. Cracks or damage inside the concrete structure act as stress relief in the wave propagation path. The amplitude of the wave and the transmission energy will decrease due to the existence of cracks or damage. Experiments were performed on two bored piles instrumented with embedded piezoceramic transducers. The experimental results demonstrate the effectiveness of the proposed approach for pile damage detection. (fast track communication)
Sliwka, Marcin
2004-01-01
The aim of this paper was to present the main rules concerning the burden of proof in polish civil trials, including medical cases. This paper also describes the subject of evidence were presented and explained. The court influence on evidence procedure was also analysed. The effect of the institution of informed consent on burden of proof in polish civil law is also described. This paper includes numerous High Court sentences on evidential and medical issues.
The strength research of the adhesive joints of sheet structures ...
African Journals Online (AJOL)
The research results of stress-strained condition of constructional sheet materials are given in the article. The strength dependence on type, configuration and sizes of adhesive joints is analyzed. The research of the strength dependence was made on the samples from bakelite plywood with the main types of adhesive joints ...
IIW guidelines on weld quality in relationship to fatigue strength
Jonsson, Bertil; Hobbacher, A F; Kassner, M; Marquis, G
2016-01-01
This book presents guidelines on quantitative and qualitative measures of the geometric features and imperfections of welds to ensure that it meets the fatigue strength requirements laid out in the recommendations of the IIW (International Institute of Welding). Welds that satisfy these quality criteria can be assessed in accordance with existing IIW recommendations based on nominal stress, structural stress, notch stress or linear fracture mechanics. Further, the book defines more restrictive acceptance criteria based on weld geometry features and imperfections with increased fatigue strength. Fatigue strength for these welds is defined as S-N curves expressed in terms of nominal applied stress or hot spot stress. Where appropriate, reference is made to existing quality systems for welds.In addition to the acceptance criteria and fatigue assessment curves, the book also provides guidance on their inspection and quality control. The successful implementation of these methods depends on adequate training for o...
Proof-of-concept study of a marine ion-selective optical sensing instrument
Sobron, P.; Thompson, C.; Bamsey, M.
2013-12-01
We have developed a proof-of-concept instrument for real-time in-situ characterization of the ion chemistry of the ocean. Our instrument uses optical sensors equipped with ion-selective membranes which exhibit a change in an optical property that can be correlated with the concentration of a specific ion. We have implemented a system for multi-ion sensing that includes the use of a single spectrometer in tandem with a fiber optic multiplexer that is capable of reading a suite of attached optrodes, each of them dedicated to a unique ion. In this abstract we report the experimental characterization of calcium and potassium optrodes as a template for ion-selective optrodes and their application to the characterization of the oceans. The tests were performed at the Controlled Environment Systems Research Facility of the University of Guelph. Guelph's optrode housing was tested by immersing it in a 1/2 strength Hoagland's hydroponic solution to test functionality of the K+ and Ca2+ optrodes in this environment. Our results demonstrate the feasibility of recording spectral information in sub-minute times from more than one optrode simultaneously in a given aqueous system. This proof-of-concept study has allowed us to measure parameters of interest and comparison to analytical predictions for critical subsystems of a deployable system, and demonstrates maturity of the multi-ion sensing optrode technology. Critical advantages of our optrode system are that it: (1) enables concurrent measurements of multiple ionic species relevant in ocean sciences; (2) has high time and spatial resolution; (3) has low limits of detection; (4) uses low-cost, low-mass, energy efficient optoelectronics. Our system has the potential for facilitating new observational, experimental, and analytic capabilities in ocean sciences, including: (a) health and environment monitoring; (b) aquaculture; (c) global change, e.g. ocean acidification; and (d) origin of life research. Proof-of-concept setup at
Affecting the Flow of a Proof by Creating Presence--A Case Study in Number Theory
Gabel, Mika; Dreyfus, Tommy
2017-01-01
The notion of flow of a proof encapsulates mathematical, didactical, and contextual aspects of proof presentation. A proof may have different flows, depending on the lecturer's choices regarding its presentation. Adopting Perelman's New Rhetoric (PNR) as a theoretical framework, we designed methods to assess aspects of the flow of a proof. We…
On Mathematicians' Proof Skimming: A Reply to Inglis and Alcock
Weber, Keith; Mejia-Ramos, Juan Pablo
2013-01-01
n a recent article, Inglis and Alcock (2012) contended that their data challenge the claim that when mathematicians validate proofs, they initially skim a proof to grasp its main idea before reading individual parts of the proof more carefully. This result is based on the fact that when mathematicians read proofs in their study, on average their…
Stress-strain effects in alumina-Cu reinforced Nb3Sn wires fabricated by the tube process
International Nuclear Information System (INIS)
Murase, Satoru; Nakayama, Shigeo; Masegi, Tamaki; Koyanagi, Kei; Nomura, Shunji; Shiga, Noriyuki; Kobayashi, Norio; Watanabe, Kazuo.
1997-01-01
In order to fabricate a large-bore, high-field magnet which achieves a low coil weight and volume, a high strength compound superconducting wire is required. For those demands we have developed the reinforced Nb 3 Sn wire using alumina dispersion strengthened copper (alumina-Cu) as a reinforcement material and the tube process of the Nb 3 Sn wire fabrication. The ductility study of the composites which consisted of the reinforcement, Nb tube, Cu, and Cu clad Sn brought a 1 km long alumina-Cu reinforced Nb 3 Sn wire successfully. Using fabricated wires measurements and evaluations of critical current density as parameters of magnetic field, tensile stress, tensile strain, and transverse compressive stress, and those of stress-strain curves at 4.2 K were performed. They showed superior performance such as high 0.3% proof stress (240 MPa at 0.3% strain) and high maximum tolerance stress (320 MPa) which were two times as large as those of conventional Cu matrix Nb 3 Sn wire. The strain sensitivity parameters were obtained for the reinforced Nb 3 Sn wire and the Cu matrix one using the scaling law. Residual stress of the component materials caused by cooling down to 4.2 K from heat-treatment temperature was calculated using equivalent Young's modulus, equivalent yield strength, thermal expansion coefficient and other mechanical parameters. Calculated stress-strain curves at 4.2 K for the reinforced Nb 3 Sn wire and the Cu matrix one based on calculation of residual stress, had good agreement with the experimental values. (author)
Creep strength and rupture ductility of creep strength enhanced ferritic steels
Energy Technology Data Exchange (ETDEWEB)
Kushima, Hideaki; Sawada, Kota; Kimura, Kazuhiro [National Inst. for Materials Science, Tsukuba, Ibaraki (Japan)
2010-07-01
Creep strength and rupture ductility of Creep Strength Enhanced Ferritic (CSEF) steels were investigated from a viewpoint of stress dependence in comparison with conventional low alloy ferritic creep resistant steels. Inflection of stress vs. time to rupture curve was observed at 50% of 0.2% offset yield stress for both CSEF and conventional ferritic steels. Creep rupture ductility tends to decrease with increase in creep exposure time, however, those of conventional low alloy steels indicate increase in the long-term. Creep rupture ductility of the ASME Grades 92 and 122 steels indicates drastic decrease with decrease in stress at 50% of 0.2% offset yield stress. Stress dependence of creep rupture ductility of the ASME Grades 92 and 122 steels is well described by stress ratio to 0.2% offset yield stress, regardless of temperature. Drop of creep rupture ductility is caused by inhomogeneous recovery at the vicinity of prior austenite grain boundary, and remarkable drop of creep rupture ductility of CSEF steels should be derived from those stabilized microstructure. (orig.)
The “ductility exhaustion” method for static strength assessment of fusion structures
Energy Technology Data Exchange (ETDEWEB)
Thompson, Vaughan, E-mail: vaughan.thompson@ccfe.ac.uk; Vizvary, Zsolt
2015-10-15
Graphical abstract: - Highlights: • Reduced conservatism and more complex geometry. • Assessment process simplified. • Gives insight into real material behaviour – virtual proof test. • Leads onto structural failure modelling. • Ductility exhaustion and global plastic collapse structural assessment. - Abstract: The traditional method for static strength assessment of structures uses elastic stresses computed along critical ligaments and then divided into categories depending on their nature e.g. bending/membrane and primary/secondary. More recently, highly realistic plastic simulations are possible using FE (finite elements) which offer useful advantages over the traditional approach including (a) more accurate modelling of complex geometries, (b) a more straightforward assessment process and (c) a less conservative approach. The plastic analysis must consider both global and local effects, and the paper looks in detail at the “ductility exhaustion” method for the latter. Simple test cases show how the method can be applied in both the Abaqus and ANSYS FE Codes and for the case of a JET beryllium tile, the method has improved reserve factors for disruption loads considerably to the point where the lower operating temperature can be safely lowered from 200 °C to 100 °C where the low ductility of beryllium is an issue.
Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko
2016-02-01
There is a strong demand for biomedical Co-Cr-based cast alloys with enhanced mechanical properties for use in dental applications. We present a design strategy for development of Co-Cr-based cast alloys with very high strength, comparable to that of wrought Co-Cr alloys, without loss of ductility. The strategy consists of simultaneous doping of nitrogen and carbon, accompanied by increasing of the Cr content to increase the nitrogen solubility. The strategy was verified by preparing Co-33Cr-9W-0.35N-(0.01-0.31)C (mass%) alloys. We determined the carbon concentration dependence of the microstructures and their mechanical properties. Metal ion release of the alloys in an aqueous solution of 0.6% sodium chloride (NaCl) and 1% lactic acid was also evaluated to ensure their corrosion resistance. As a result of the nitrogen doping, the formation of a brittle σ-phase, a chromium-rich intermetallic compound, was significantly suppressed. Adding carbon to the alloys resulted in finer-grained microstructures and carbide precipitation; accordingly, the strength increased with increasing carbon concentration. The tensile ductility, on the other hand, increased with increasing carbon concentration only up to a point, reaching a maximum at a carbon concentration of ∼0.1mass% and decreasing with further carbon doping. However, the alloy with 0.31mass% of carbon exhibited 14% elongation and also possessed very high strength (725MPa in 0.2% proof stress). The addition of carbon did not significantly degrade the corrosion resistance. The results show that our strategy realizes a novel high-strength Co-Cr-based cast alloy that can be produced for advanced dental applications using a conventional casting procedure. The present study suggested a novel alloy design concept for realizing high-strength Co-Cr-based cast alloys. The proposed strategy is beneficial from the practical point of view because it uses conventional casting approach-a simpler, more cost-effective, industrially
Seismic-Proof Buildings in Developing Countries
Directory of Open Access Journals (Sweden)
Vittoria Laghi
2017-08-01
Full Text Available The use of “ductile seismic frames,” whose proper seismic behavior largely depends upon construction details and specific design rules, may do not always lead to effective seismic resistant structures, as dramatically denounced by the famous Chinese artist Ai Weiwei in his artwork Straight. The artwork (96 t of undulating metal bars that were salvaged from schools destroyed by the 2008 Sichuan, China earthquake, where over 5,000 students were killed is a clear denounce against the corruption yielding to shoddy construction methods. The issue of safe constructions against natural hazards appears even more important in developing countries where, in most cases, building structures are realized by non-expert workers, or even by simple “people from the street,” who does not have any technical knowledge on construction techniques and seismic engineering. In this paper, a brief history from the first frame structures to the more efficient wall-based structures is provided within Earthquake Engineering perspectives. The superior structural properties of box-type wall structures with respect to conventional frame structures envisage a change of paradigm from actual “ductility-based” Earthquake Engineering (centered on frame structures toward 100% safe buildings through a “strength-based” design exploiting the use of box-type wall-based structures.
Burst strength of tubing and casing based on twin shear unified strength theory.
Lin, Yuanhua; Deng, Kuanhai; Sun, Yongxing; Zeng, Dezhi; Liu, Wanying; Kong, Xiangwei; Singh, Ambrish
2014-01-01
The internal pressure strength of tubing and casing often cannot satisfy the design requirements in high pressure, high temperature and high H2S gas wells. Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design. The ISO 10400: 2007 provides the model which can calculate the burst strength of tubing and casing better than API 5C3 standard, but the calculation accuracy is not desirable because about 50 percent predictive values are remarkably higher than real burst values. So, for the sake of improving strength design of tubing and casing, this paper deduces the plastic limit pressure of tubing and casing under internal pressure by applying the twin shear unified strength theory. According to the research of the influence rule of yield-to-tensile strength ratio and mechanical properties on the burst strength of tubing and casing, the more precise calculation model of tubing-casing's burst strength has been established with material hardening and intermediate principal stress. Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models. The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.
Statistical Analysis Of Failure Strength Of Material Using Weibull Distribution
International Nuclear Information System (INIS)
Entin Hartini; Mike Susmikanti; Antonius Sitompul
2008-01-01
In evaluation of ceramic and glass materials strength a statistical approach is necessary Strength of ceramic and glass depend on its measure and size distribution of flaws in these material. The distribution of strength for ductile material is narrow and close to a Gaussian distribution while strength of brittle materials as ceramic and glass following Weibull distribution. The Weibull distribution is an indicator of the failure of material strength resulting from a distribution of flaw size. In this paper, cumulative probability of material strength to failure probability, cumulative probability of failure versus fracture stress and cumulative probability of reliability of material were calculated. Statistical criteria calculation supporting strength analysis of Silicon Nitride material were done utilizing MATLAB. (author)
Energy Technology Data Exchange (ETDEWEB)
Van Hoorik, P.; Westerga, R. [Energy Valley, Groningen (Netherlands)
2011-05-15
The SmartProofs program aims to develop tools which must show that the principle of a Smart Power System (SPS) works and how. An SPS can ensure that the supply and demand of electricity in the grid is balanced, even in case more decentralized energy techniques will be put into use. This final report summarizes the main results and conclusions of the SmartProofs program. As part of the SPS program attention is paid to the impacts on the girds, the effects of centralized and decentralized management, disaster resilience, pricing models, potential benefits of control and new business models [Dutch] Het SmartProofs programma heeft tot doel om een concept van een Smart Power System (SPS) te ontwikkelen waarmee kan worden aangetoond dat het principe van een SPS werkt en op welke manier. Een SPS kan zorgen dat het aanbod van elektriciteit op het net op elk moment van de dag overeenkomt met de vraag, ook als er straks veel meer decentrale energietechnieken gebruikt worden waarmee zowel de vraag als het aanbod van elektriciteit onvoorspelbaar wordt. Dit eindrapport geeft een overzicht van de belangrijkste resultaten en conclusies van het SmartProofs programma. Het programma heeft in de werkpakketten deelvraagstukken rondom SmartProofS onderzocht rondom de effecten op onze energienetten, de effecten van zowel centrale- als decentrale aansturing, disaster resilience, prijsmodellen, mogelijke baten van aansturing en nieuwe business modellen.
Co-constructive Logics for Proofs and Refutations
Directory of Open Access Journals (Sweden)
Trafford James
2015-01-01
Full Text Available This paper considers logics which are formally dual to intuitionistic logic in order to investigate a co-constructive logic for proofs and refutations. This is philosophically motivated by a set of problems regarding the nature of constructive truth, and its relation to falsity. It is well known both that intuitionism can not deal constructively with negative information, and that defining falsity by means of intuitionistic negation leads, under widely-held assumptions, to a justification of bivalence. For example, we do not want to equate falsity with the non-existence of a proof since this would render a statement such as “pi is transcendental” false prior to 1882. In addition, the intuitionist account of negation as shorthand for the derivation of absurdity is inadequate, particularly outside of purely mathematical contexts. To deal with these issues, I investigate the dual of intuitionistic logic, co-intuitionistic logic, as a logic of refutation, alongside intuitionistic logic of proofs. Direct proof and refutation are dual to each other, and are constructive, whilst there also exist syntactic, weak, negations within both logics. In this respect, the logic of refutation is weakly paraconsistent in the sense that it allows for statements for which, neither they, nor their negation, are refuted. I provide a proof theory for the co-constructive logic, a formal dualizing map between the logics, and a Kripke-style semantics. This is given an intuitive philosophical rendering in a re-interpretation of Kolmogorov's logic of problems.
Reversal burden of proof on corruption in Indonesia
Directory of Open Access Journals (Sweden)
Hibnu Nugroho
2018-03-01
Full Text Available Corruption becomes the greatest enemy most countries face including Indonesia. Commitment to eradicate corruption significantly increases yet it would be meaningless if it is not supported by adequate legislation to implement the law effectively. Reversal burden of proof essentially aims to facilitate law enforcers to seek and disclose assets a suspect owns allegedly as corruption crime. The principle of reversal burden of proof was originated from Anglo-Saxon countries and this still applies to certain cases such as bribery-related gratifications as Malaysia and Singapore implement. In Indonesia, provisions on the principle of reversal burden of proof have been long recognized even since 1960 on the first law on corruption crimes. Nevertheless, for more than a half of century, the provision on reversal burden of proof has never been implemented. It occurs since articles which govern the issues barely provide clear regulation. It only mentions the principle yet never issues an implemented regulation to support the principle. In regards to this, the research is aimed at investigating, seeking and analyzing the weaknesses in implementing the principle of reversal burden of proof in corruption crimes recently as well as discussing obstacles in law enforcement.
Tensile Strength of Water Exposed to Pressure Pulses
DEFF Research Database (Denmark)
Andersen, Anders Peter; Mørch, Knud Aage
2012-01-01
at an extended water-solid interface by imposing a tensile stress pulse which easily causes cavitation. Next, a compressive pulse of duration ~1 ms and a peak intensity of a few bar is imposed prior to the tensile stress pulse. A dramatic increase of the tensile strength is observed immediately after......It is well known that pressurization for an extended period of time increases the tensile strength of water, but little information is available on the effect of pressure pulses of short duration. This is addressed in the present paper where we first measure the tensile strength of water...
Upper extremity injuries associated with strength training.
Haupt, H A
2001-07-01
Most injuries sustained during strength training are mild strains that resolve with appropriate rest. More severe injuries include traumatic shoulder dislocations, tendon ruptures of the pectoralis major, biceps, and triceps; stress fractures of the distal clavicle, humerus, radius, and ulna; traumatic fractures of the distal radius and ulna in adolescent weightlifters; and compressive and stretch neuropathies. These more severe injuries are usually the result of improperly performing a strength training exercise. Educating athletes regarding proper strength-training techniques serves to reverse established injury patterns and to prevent these injuries in the first place. Recognizing the association of anabolic steroid use to several of the injury patterns further reinforces the need for medical specialists to counsel athletes against their use. With the increasing use of supplements such as creatine, the incidence and nature of strength-training injuries may change further. Greater emphasis on the competitive performance of younger athletes undoubtedly will generate enthusiasm for strength training at earlier ages in both sexes. The importance of proper supervision of these young athletes by knowledgeable persons will increase. As the popularity of strength training grows, there will be ample opportunity to continue to catalog the injury patterns associated with this activity.
2010-07-01
... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Proof of onset of leukemia at least two... Participants § 79.35 Proof of onset of leukemia at least two years after first exposure, and proof of onset of... be the date of first or initial exposure. The date of onset will be the date of diagnosis as...
Modelling of tension stiffening for normal and high strength concrete
DEFF Research Database (Denmark)
Christiansen, Morten Bo; Nielsen, Mogens Peter
1998-01-01
form the model is extended to apply to biaxial stress fields as well. To determine the biaxial stress field, the theorem of minimum complementary elastic energy is used. The theory has been compared with tests on rods, disks, and beams of both normal and high strength concrete, and very good results...
SOME CONSIDERATIONS REGARDING THE STRENGTH CALCULUS OF A LATHE TOOL
Directory of Open Access Journals (Sweden)
Catălin ROŞU
2013-05-01
Full Text Available In this paper a strength calculus of a lathe tool is made. The main purpose of this study is to determineequivalent stress relations that can be useful for an engineer in the design situation. The simplifying assumptionsand the equivalent stress relations are presented from an original point of view.
Processing, structure and flexural strength of CNT and carbon fibre ...
Indian Academy of Sciences (India)
Administrator
1Department of Mechanical Engineering, Vignan Institute of Technology and Science, Deshmukhi, ... perties include primarily the tensile stress, flexural stress and fracture parameters. However ... The present work is an attempt to bring out the flexural strength ..... lating Materials Annual Book of ASTM Standards American.
NASA Finds Direct Proof of Dark Matter
2006-08-01
Dark matter and normal matter have been wrenched apart by the tremendous collision of two large clusters of galaxies. The discovery, using NASA's Chandra X-ray Observatory and other telescopes, gives direct evidence for the existence of dark matter. "This is the most energetic cosmic event, besides the Big Bang, which we know about," said team member Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. Lensing Illustration Gravitational Lensing Explanation These observations provide the strongest evidence yet that most of the matter in the universe is dark. Despite considerable evidence for dark matter, some scientists have proposed alternative theories for gravity where it is stronger on intergalactic scales than predicted by Newton and Einstein, removing the need for dark matter. However, such theories cannot explain the observed effects of this collision. "A universe that's dominated by dark stuff seems preposterous, so we wanted to test whether there were any basic flaws in our thinking," said Doug Clowe of the University of Arizona at Tucson, and leader of the study. "These results are direct proof that dark matter exists." Animation of Cluster Collision Animation of Cluster Collision In galaxy clusters, the normal matter, like the atoms that make up the stars, planets, and everything on Earth, is primarily in the form of hot gas and stars. The mass of the hot gas between the galaxies is far greater than the mass of the stars in all of the galaxies. This normal matter is bound in the cluster by the gravity of an even greater mass of dark matter. Without dark matter, which is invisible and can only be detected through its gravity, the fast-moving galaxies and the hot gas would quickly fly apart. The team was granted more than 100 hours on the Chandra telescope to observe the galaxy cluster 1E0657-56. The cluster is also known as the bullet cluster, because it contains a spectacular bullet-shaped cloud of hundred
A Strength Model and Service Envelope for PBX 9501
Energy Technology Data Exchange (ETDEWEB)
Stevens, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-02-05
An analytical method is proposed for making an assessment of the severity of the response of PBX 9501 in structural response simulations. The approach is based on the coherent use of a strength model and a failure criterion. The strength model is based on a creep rupture function and an associated cumulative damage model. The material's residual strength at any time during a simulation of structural response is determined by taking into account both the actual stress history up to that time, and a hypothetical continuation of the applied stresses that are assumed to grow until material failure results. The residual strength is used by the failure criterion to define the region of safe (non-failed) material response. The Mohr-Coulomb failure criterion is chosen for its general applicability to materials with both cohesive and frictional strength. The combined use of the residual strength model and the failure criterion provides a quantitative method of assessing the severity of the response of PBX 9501 material in structural simulations: the proximity of any evolving, general state of stress to the failure surface (which shrinks due to the cumulative damage caused by the past stress history) can be calculated and used as a measure of margin to failure. The strength model has been calibrated to a broad range of uniaxial tension and compression tests, and a small set of creep tests, and is applicable to a broad range of loading conditions.
Computer-aided proofs for multiparty computation with active security
DEFF Research Database (Denmark)
Haagh, Helene; Karbyshev, Aleksandr; Oechsner, Sabine
2018-01-01
Secure multi-party computation (MPC) is a general cryptographic technique that allows distrusting parties to compute a function of their individual inputs, while only revealing the output of the function. It has found applications in areas such as auctioning, email filtering, and secure...... teleconference. Given its importance, it is crucial that the protocols are specified and implemented correctly. In the programming language community it has become good practice to use computer proof assistants to verify correctness proofs. In the field of cryptography, EasyCrypt is the state of the art proof...... public-key encryption, signatures, garbled circuits and differential privacy. Here we show for the first time that it can also be used to prove security of MPC against a malicious adversary. We formalize additive and replicated secret sharing schemes and apply them to Maurer's MPC protocol for secure...
Completing the proof of “Generic quantum nonlocality”
Energy Technology Data Exchange (ETDEWEB)
Gachechiladze, Mariami; Gühne, Otfried, E-mail: otfried.guehne@uni-siegen.de
2017-04-18
In a paper by Popescu and Rohrlich a proof has been presented showing that any pure entangled multiparticle quantum state violates some Bell inequality. We point out a gap in this proof, but we also give a construction to close this gap. It turns out that with some extra effort all the results from the aforementioned publication can be proven. Our construction shows how two-particle entanglement can be generated via performing local projections on a multiparticle state. - Highlights: • A proof is completed, showing that any pure entangled multiparticle quantum state violates some Bell inequality. • The results demonstrate how an multi-qubit state can be transformed by local measurements to a two-qubit entangled state. • The extension to higher dimensions is discussed.
US NDC Modernization: Service Oriented Architecture Proof of Concept
Energy Technology Data Exchange (ETDEWEB)
Hamlet, Benjamin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Encarnacao, Andre Villanova [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jackson, Keilan R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hays, Ian A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barron, Nathan E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Simon, Luke B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Harris, James M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Young, Christopher J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-12-01
This report is a progress update on the US NDC Modernization Service Oriented Architecture (SOA) study describing results from a proof of concept project completed from May through September 2013. Goals for this proof of concept are 1) gain experience configuring, using, and running an Enterprise Service Bus (ESB), 2) understand the implications of wrapping existing software in standardized interfaces for use as web services, and 3) gather performance metrics for a notional seismic event monitoring pipeline implemented using services with various data access and communication patterns. The proof of concept is a follow on to a previous SOA performance study. Work was performed by four undergraduate summer student interns under the guidance of Sandia staff.
The Development of Proofs in Analytical Mathematics for Undergraduate Students
Ali, Maselan; Sufahani, Suliadi; Hasim, Nurnazifa; Saifullah Rusiman, Mohd; Roslan, Rozaini; Mohamad, Mahathir; Khalid, Kamil
2018-04-01
Proofs in analytical mathematics are essential parts of mathematics, difficult to learn because its underlying concepts are not visible. This research consists of problems involving logic and proofs. In this study, a short overview was provided on how proofs in analytical mathematics were used by university students. From the results obtained, excellent students obtained better scores compared to average and poor students. The research instruments used in this study consisted of two parts: test and interview. In this way, analysis of students’ actual performances can be obtained. The result of this study showed that the less able students have fragile conceptual and cognitive linkages but the more able students use their strong conceptual linkages to produce effective solutions
Completing the proof of “Generic quantum nonlocality”
International Nuclear Information System (INIS)
Gachechiladze, Mariami; Gühne, Otfried
2017-01-01
In a paper by Popescu and Rohrlich a proof has been presented showing that any pure entangled multiparticle quantum state violates some Bell inequality. We point out a gap in this proof, but we also give a construction to close this gap. It turns out that with some extra effort all the results from the aforementioned publication can be proven. Our construction shows how two-particle entanglement can be generated via performing local projections on a multiparticle state. - Highlights: • A proof is completed, showing that any pure entangled multiparticle quantum state violates some Bell inequality. • The results demonstrate how an multi-qubit state can be transformed by local measurements to a two-qubit entangled state. • The extension to higher dimensions is discussed.
Factors and factorizations of graphs proof techniques in factor theory
Akiyama, Jin
2011-01-01
This book chronicles the development of graph factors and factorizations. It pursues a comprehensive approach, addressing most of the important results from hundreds of findings over the last century. One of the main themes is the observation that many theorems can be proved using only a few standard proof techniques. This stands in marked contrast to the seemingly countless, complex proof techniques offered by the extant body of papers and books. In addition to covering the history and development of this area, the book offers conjectures and discusses open problems. It also includes numerous explanatory figures that enable readers to progressively and intuitively understand the most important notions and proofs in the area of factors and factorization.
On mathematicians' different standards when evaluating elementary proofs.
Inglis, Matthew; Mejia-Ramos, Juan Pablo; Weber, Keith; Alcock, Lara
2013-04-01
In this article, we report a study in which 109 research-active mathematicians were asked to judge the validity of a purported proof in undergraduate calculus. Significant results from our study were as follows: (a) there was substantial disagreement among mathematicians regarding whether the argument was a valid proof, (b) applied mathematicians were more likely than pure mathematicians to judge the argument valid, (c) participants who judged the argument invalid were more confident in their judgments than those who judged it valid, and (d) participants who judged the argument valid usually did not change their judgment when presented with a reason raised by other mathematicians for why the proof should be judged invalid. These findings suggest that, contrary to some claims in the literature, there is not a single standard of validity among contemporary mathematicians. Copyright © 2013 Cognitive Science Society, Inc.
Proofs of the Cantor-Bernstein theorem a mathematical excursion
Hinkis, Arie
2013-01-01
This book offers an excursion through the developmental area of research mathematics. It presents some 40 papers, published between the 1870s and the 1970s, on proofs of the Cantor-Bernstein theorem and the related Bernstein division theorem. While the emphasis is placed on providing accurate proofs, similar to the originals, the discussion is broadened to include aspects that pertain to the methodology of the development of mathematics and to the philosophy of mathematics. Works of prominent mathematicians and logicians are reviewed, including Cantor, Dedekind, Schröder, Bernstein, Borel, Zermelo, Poincaré, Russell, Peano, the Königs, Hausdorff, Sierpinski, Tarski, Banach, Brouwer and several others mainly of the Polish and the Dutch schools. In its attempt to present a diachronic narrative of one mathematical topic, the book resembles Lakatos’ celebrated book Proofs and Refutations. Indeed, some of the observations made by Lakatos are corroborated herein. The analogy between the two books is clearly an...
Towards Verification of Constituent Systems through Automated Proof
DEFF Research Database (Denmark)
Couto, Luis Diogo Monteiro Duarte; Foster, Simon; Payne, R
2014-01-01
This paper explores verification of constituent systems within the context of the Symphony tool platform for Systems of Systems (SoS). Our SoS modelling language, CML, supports various contractual specification elements, such as state invariants and operation preconditions, which can be used...... to specify contractual obligations on the constituent systems of a SoS. To support verification of these obligations we have developed a proof obligation generator and theorem prover plugin for Symphony. The latter uses the Isabelle/HOL theorem prover to automatically discharge the proof obligations arising...... from a CML model. Our hope is that the resulting proofs can then be used to formally verify the conformance of each constituent system, which is turn would result in a dependable SoS....
Strength Calculation of Locally Loaded Orthotropic Shells
Directory of Open Access Journals (Sweden)
Yu. I. Vinogradov
2015-01-01
Full Text Available The article studies laminated orthotropic cylindrical, conic, spherical, and toroidal shells, which are often locally loaded in the aircraft designs over small areas of their surfaces.The aim of this work is to determine stress concentration in shells versus structure of orthotropic composite material, shell form and parameters, forms of loading areas, which borders do not coincide with lines of main curvatures of shells. For this purpose, an analytical computing algorithm to estimate strength of shells in terms of stress is developed. It enables us to have solution results of the boundary value problem with a controlled error. To solve differential equations an analytical method is used. An algorithm of the boundary value problem solution is multiplicative.The main results of researches are graphs of stress concentration in the orthotropic shells versus their parameters and areas of loading lineated by circles and ellipses.Among the other works aimed at determination of stress concentration in shells, the place of this one is defined by the analytical solution of applied problems for strength estimation in terms of shell stresses of classical forms.The developed effective analytical algorithm to solve the boundary value problem and received results are useful in research and development.
Influence of initial imperfections on ultimate strength of spherical shells
Directory of Open Access Journals (Sweden)
Chang-Li Yu
2017-09-01
Full Text Available Comprehensive consideration regarding influence mechanisms of initial imperfections on ultimate strength of spherical shells is taken to satisfy requirement of deep-sea structural design. The feasibility of innovative numerical procedure that combines welding simulation and non-linear buckling analysis is verified by a good agreement to experimental and theoretical results. Spherical shells with a series of wall thicknesses to radius ratios are studied. Residual stress and deformations from welding process are investigated separately. Variant influence mechanisms are discovered. Residual stress is demonstrated to be influential to stress field and buckling behavior but not to the ultimate strength. Deformations are proved to have a significant impact on ultimate strength. When central angles are less than critical value, concave magnitudes reduce ultimate strengths linearly. However, deformations with central angles above critical value are of much greater harm. Less imperfection susceptibility is found in spherical shells with larger wall thicknesses to radius ratios.
Frictional strength of wet and dry montmorillonite
Morrow, C. A.; Moore, D. E.; Lockner, D. A.
2017-05-01
Montmorillonite is a common mineral in fault zones, and its low strength relative to other common gouge minerals is important in many models of fault rheology. However, the coefficient of friction, μ, varies with degree of saturation and is not well constrained in the literature due to the difficulty of establishing fully drained or fully dried states in the laboratory. We measured μ of both saturated and oven-dried montmorillonite at normal stresses up to 700 MPa. Care was taken to shear saturated samples slowly enough to avoid pore fluid overpressure. For saturated samples, μ increased from 0.10 to 0.28 with applied effective normal stress, while for dry samples μ decreased from 0.78 to 0.45. The steady state rate dependence of friction, (a - b), was positive, promoting stable sliding. The wide disparity in reported frictional strengths can be attributed to experimental procedures that promote differing degrees of partial saturation or overpressured pore fluid conditions.
Alumina strength degradation in the elastic regime
International Nuclear Information System (INIS)
Furnish, Michael D.; Chhabildas, Lalit C.
1998-01-01
Measurements of Kanel et al. [1991] have suggested that deviatoric stresses in glasses shocked to nearly the Hugoniot Elastic Limit (HEL) relax over a time span of microseconds after initial loading. 'Failure' (damage) waves have been inferred on the basis of these measurements using time-resolved manganin normal and transverse stress gauges. Additional experiments on glass by other researchers, using time-resolved gauges, high-speed photography and spall strength determinations have also lead to the same conclusions. In the present study we have conducted transmitted-wave experiments on high-quality Coors AD995 alumina shocked to roughly 5 and 7 GPa (just below or at the HEL). The material is subsequently reshocked to just above its elastic limit. Results of these experiments do show some evidence of strength degradation in the elastic regime
Strength measurement of optical fibers by bending
Srubshchik, Leonid S.
1999-01-01
A two-point bending technique has been used not only to measure the breaking stress of optical fiber but also to predict its static and dynamic fatigue. The present theory of this test is based on elastica theory of rod. However, within the limits of elastica theory the tensile and shear stresses cannot be determined. In this paper we study dynamic and static problems for optical fiber in the two- point bending test on the base of geometrically exact theory in which rod can suffer flexure, extension, and shear. We obtain the governing partial differential equations taking into account the fact that the lateral motion of the fiber is restrained by the presence of flat parallel plates. We develop the computational methods for solving the initial and equilibrium free-boundary nonlinear planar problems. We derive the formulas for predicting of the tensile strength from strength in the bending and calculate one example.
Proof of cipher text ownership based on convergence encryption
Zhong, Weiwei; Liu, Zhusong
2017-08-01
Cloud storage systems save disk space and bandwidth through deduplication technology, but with the use of this technology has been targeted security attacks: the attacker can get the original file just use hash value to deceive the server to obtain the file ownership. In order to solve the above security problems and the different security requirements of cloud storage system files, an efficient information theory security proof of ownership scheme is proposed. This scheme protects the data through the convergence encryption method, and uses the improved block-level proof of ownership scheme, and can carry out block-level client deduplication to achieve efficient and secure cloud storage deduplication scheme.
Coqoon - An IDE for Interactive Proof Development in Coq
DEFF Research Database (Denmark)
Faithfull, Alexander; Bengtson, Jesper; Tassi, Enrico
2016-01-01
User interfaces for interactive proof assistants have always lagged behind those for mainstream programming languages. Whereas integrated development environments—IDEs—have support for features like project management, version control, dependency analysis and incremental project compilation, “IDE...... these projects using the Eclipse common build system. Coqoon takes advantage of the latest features of Coq, including asynchronous and parallel processing of proofs, and—when used together with a third-party OCaml extension for Eclipse—can even be used to work on large developments containing Coq plugins....
Proof of the fundamental BCJ relations for QCD amplitudes
International Nuclear Information System (INIS)
Cruz, Leonardo de la; Kniss, Alexander; Weinzierl, Stefan
2015-01-01
The fundamental BCJ-relation is a linear relation between primitive tree amplitudes with different cyclic orderings. The cyclic orderings differ by the insertion place of one gluon. The coefficients of the fundamental BCJ-relation are linear in the Lorentz invariants 2p_ip_j. The BCJ-relations are well established for pure gluonic amplitudes as well as for amplitudes in N=4 super-Yang-Mills theory. Recently, it has been conjectured that the BCJ-relations hold also for QCD amplitudes. In this paper we give a proof of this conjecture. The proof is valid for massless and massive quarks.