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101.
Michael E. Sigman Mary R. Williams Joseph A. Castelbuono Joseph G. Colca C. Douglas Clark 《仪器科学与技术》2013,41(4):375-393
Abstract The mass spectra calculated by summing the intensities of each nominal mass over all chromatographic times, the summed ion spectra, were calculated for a set of 440 commercially available ignitable liquids that had been analyzed by gas chromatography–mass spectrometry. Each ignitable liquid is generally comprised of a mixture of chemicals, and the mixtures may be very complex in some cases, e.g., petroleum distillates, gasoline, etc. The summed ion spectra were evaluated to determine if they contained sufficient information content to allow their use for rapid and accurate identification of the ignitable liquid in a database or library. The summed ion nominal mass spectra were encoded in one bit per channel at 1% transition intensity and a set of 96,580 unique pairwise comparisons were made between spectra, resulting in an average of approximately 50 differing channels per comparison. A subset of 62 summed ion spectra were further compared by a similarity metric and found by cluster analysis to group closely along the ASTM ignitable liquid classification scheme. Receiver operator characteristic analysis of the use of the similarity index in combination with the summed ion spectra was shown to provide 99% probability of correct liquid identification and 95% probability of correct ASTM classification by primary and sub-class. Interlaboratory tests found 95% probability of correct liquid identification and 85% probability of correct ASTM classification at the primary class level. These results demonstrate the use of the summed ion spectrum as a first step in the rapid identification of an ignitable liquid by database or library searching. 相似文献
102.
Analysis of the problem of a plane infinite elastic body with a centrally located crack subject to uniform biaxial load along the remote outer boundaries, indicates that loads applied parallel to the crack influence the value of the critical (fracture) tensile load applied perpendicular to it, with the Poisson ratio of the material determining the characteristics of this influence. Experimental information from specially designed biaxial test programs, obtained by the authors and also from the published data of other investigators, shows that, while tensile loads parallel to the crack raise the critical value of perpendicular load for an aluminum alloy, they have a reverse effect on the critical load for plexiglass (polymethylmethacrylate or PMMA), in qualitative agreement with the predictions of the analysis.
No menclature 2 crack length - (x, y), (r, ), (, ) rectangular, polar, elliptic coordinates, respectively - z x +iy, complex variable - t jk ,e jk components of the stress and strain tensors, respectively - T k ,u k ,b k components of the surface traction, displacement and body force vectors, respectively - t xx ,t xy ,t yy rectangular stress components - t ,t ,t elliptic stress components - u x ,u y ;u ,u rectangular and elliptic displacement components, respectively - U elastic strain energy per unit thickness - W work of forces applied to the body per unit thickness - P, V potential energies per unit thickness - surface energy per unit thickness - R bound region of thex-y plane - C 1,C 2 closed boundary curves ofR - , , , sectionally holomorphic functions of the complex variablez - E Young's modulus - k applied load biaxiality ratio,t xx ()/t yy () - stress applied to the outer boundary surface - µ elastic shear modulus - Poisson's ratio - surface energy density per unit area - (3-)/(1+) for plane stress, (3-4) for plane strain 相似文献
Résumé On analyse le problème d'un corps élastique plan infini comportant une fissure centrale soumise à une contrainte biaxiale le long de ses bords éloignés. L'analyse montre que les charges appliquées parallèlement à la fissure influencent la valeur de la contrainte critique de rupture en traction appliquée perpendiculairement à elle, les caractéristiques de cette influence étant régies par le rapport de Poisson du matériau. Des informations expérimentales venant de programme d'essais en condition biaxiale spécialement conçu et recueillies par les auteurs et par la littérature publiée par d'autres chercheurs montrent que tandis que les contraintes de traction parallèles à la fissure accroissent la valeur critique de la charge perpendiculaire dans le cas d'un alliage aluminium, elles ont un effet inverse sur la charge critique dans le cas du plexiglas (polyméthyleméthacrylate ou PMMA), ceci étant en accord qualitatif avec les prédictions de l'analyse.
No menclature 2 crack length - (x, y), (r, ), (, ) rectangular, polar, elliptic coordinates, respectively - z x +iy, complex variable - t jk ,e jk components of the stress and strain tensors, respectively - T k ,u k ,b k components of the surface traction, displacement and body force vectors, respectively - t xx ,t xy ,t yy rectangular stress components - t ,t ,t elliptic stress components - u x ,u y ;u ,u rectangular and elliptic displacement components, respectively - U elastic strain energy per unit thickness - W work of forces applied to the body per unit thickness - P, V potential energies per unit thickness - surface energy per unit thickness - R bound region of thex-y plane - C 1,C 2 closed boundary curves ofR - , , , sectionally holomorphic functions of the complex variablez - E Young's modulus - k applied load biaxiality ratio,t xx ()/t yy () - stress applied to the outer boundary surface - µ elastic shear modulus - Poisson's ratio - surface energy density per unit area - (3-)/(1+) for plane stress, (3-4) for plane strain 相似文献
103.
Bound states and scattering resonances for a 3He-vacancy system in crystalline 4He are shown to exist. For realistic physical parameters the theory yields binding energies of 0.1 K. It is found that the bound states and scattering resonances tend to enhance the diffusion coefficient of 3He. The experimental consequences of this enhanced diffusion are discussed. 相似文献
104.
The authors develop an eigth-order model for bending of transversally isotropic plates and use integral transforms and a collocation
method to form a line-spring model for a cracked plate. The eigth-order model allows satisfaction of the three standard plate
bending boundary conditions; the normal moment, twisting moment, and transverse shear force, and an additional shear stress
resultant that allows analysis of transverse normal stresses near the crack tip. The line-spring model is used to develop
geometry correction factors for bending of finite-thickness plates, accounting for transverse shear deformation and pressurization
of the plate near the crack tip. The line-spring model is then applied to the problem of a plate with a reinforced crack,
and the results are used to validate an interpolation solution based on an energy method. While not explicitly analysed, the
models are applicable to many problems, including bending of bonded repairs, fracture and fatigue of composite and layered
materials, surface cracks, crack tip plasticity and crack closure or crack face interaction. 相似文献
105.
Fei Hua Sampsa Hautaniemi Rayka Yokoo Douglas A Lauffenburger 《Journal of the Royal Society Interface》2006,3(9):515-526
Mathematical models of highly interconnected and multivariate signalling networks provide useful tools to understand these complex systems. However, effective approaches to extracting multivariate regulation information from these models are still lacking. In this study, we propose a data-driven modelling framework to analyse large-scale multivariate datasets generated from mathematical models. We used an ordinary differential equation based model for the Fas apoptotic pathway as an example. The first step in our approach was to cluster simulation outputs generated from models with varied protein initial concentrations. Subsequently, decision tree analysis was applied, in which we used protein concentrations to predict the simulation outcomes. Our results suggest that no single subset of proteins can determine the pathway behaviour. Instead, different subsets of proteins with different concentrations ranges can be important. We also used the resulting decision tree to identify the minimal number of perturbations needed to change pathway behaviours. In conclusion, our framework provides a novel approach to understand the multivariate dependencies among molecules in complex networks, and can potentially be used to identify combinatorial targets for therapeutic interventions. 相似文献
106.
The question of whether mental disorders are discrete clinical conditions or arbitrary distinctions along dimensions of functioning is a long-standing issue, but its importance is escalating with the growing recognition of the frustrations and limitations engendered by the categorical model. The authors provide an overview of some of the dilemmas of the categorical model, followed by a discussion of research that addresses whether mental disorders are accurately or optimally classified categorically or dimensionally. The authors' intention is to document the importance of this issue and to suggest that future editions of the Diagnostic and Statistical Manual of Mental Disorders give more recognition to dimensional models of classification. They conclude with a dimensional mental disorder classification that they suggest provides a useful model. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
Lacreuse Agnès; Kim Charles B.; Rosene Douglas L.; Killiany Ronald J.; Moss Mark B.; Moore Tara L.; Chennareddi Lakshmi; Herndon James G. 《Canadian Metallurgical Quarterly》2005,119(1):118
The authors tested 90 rhesus monkeys (Macaca mulatta) on a task of spatial memory, the spatial Delayed Recognition Span Test. The results showed that performance declined significantly with age, males had greater scores than females, and the rate of apparent decline with age was greater in males than in females. Both working and reference memory declined with age, but only working memory showed sex differences. The authors compared these data with that of 22 monkeys who were trained on a simpler version of the task before formal testing. Training had no effect on males but dramatically improved working memory in young females. The results confirm a male advantage in spatial working memory at a young age and confirm a greater decline with age in males than in females. It is important to note that prior training completely reverses the deficits of young females. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
108.
French Douglas J.; No?l Marc; Vigneau Fran?ois; French Julie A.; Cyr Chantal P.; Evans R. Thomas 《Canadian Metallurgical Quarterly》2005,37(3):181
This study examined the psychometric properties of the PCS-CF, a French-Canadian adaptation of the Pain Catastrophizing Scale (Sullivan, Bishop & Pivik, 1995). One hundred and twenty undergraduate students (83 women; 37 men) completed the PCS-CF and measures of anxiety and depression prior to immersing their hand in ice water for 1-minute. A subset of 39 participants (28 females; 11 males) also completed a second pain task involving an ascending series of electrocutaneous stimulations. Participants' verbal and non-verbal pain behaviours during and immediately after the immersion task were recorded and subsequently independently coded. Reliability analyses revealed that the PCS-CF total score and subscale scores have a high degree of internal consistency and test-retest reliabilities that are comparable to the original Pain Catastrophizing Scale. PCS-CF scores were associated with higher levels of self-reported pain during the ice water immersion task and decreased pain tolerance during electrocutaneous stimulation. Individuals with elevated PCS-CF scores also displayed a more diverse repertoire of pain behaviours than their low PCS-CF counterparts. Previous findings that catastrophizing scores are able to discriminate criterion groups of males and females were also replicated. Given the highly correlated factors obtained in analyses of the dimensionality of the PCS-CF, the structure suggested by the authors of the original scale is only partially supported. However, the results taken together suggest that the PCS-CF is both a reliable and valid measure of the pain catastrophizing construct that is psychometrically comparable to the original PCS. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
Maner Jon K.; Kenrick Douglas T.; Becker D. Vaughn; Robertson Theresa E.; Hofer Brian; Neuberg Steven L.; Delton Andrew W.; Butner Jonathan; Schaller Mark 《Canadian Metallurgical Quarterly》2005,88(1):63
Results from 2 experimental studies suggest that self-protection and mate-search goals lead to the perception of functionally relevant emotional expressions in goal-relevant social targets. Activating a self-protection goal led participants to perceive greater anger in Black male faces (Study 1) and Arab faces (Study 2), both out-groups heuristically associated with physical threat. In Study 2, participants' level of implicit Arab-threat associations moderated this bias. Activating a mate-search goal led male, but not female, participants to perceive more sexual arousal in attractive opposite-sex targets (Study 1). Activating these goals did not influence perceptions of goal-irrelevant targets. Additionally, participants with chronic self-protective and mate-search goals exhibited similar biases. Findings are consistent with a functionalist, motivation-based account of interpersonal perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
110.
David J. Fair Rakesh Venkatesh Bruce Boghosian Douglas M. Matson 《Microgravity science and technology》2005,16(1-4):55-58
Certain commercial steel alloys exhibit a two-step phase transformation process during solidification when substantial undercooling of the liquid allows access to the metastable phase. This two-step transformation leads to a desirable microstructure under certain conditions. Electrostatic Levitation (ESL) and Electromagnetic Levitation (EML) are two methods of containerless processing used to study how nucleation and growth kinetics influence the transformation delay between phases. Because the two facilities show substantially different delay results, the test environment differences have been analyzed to determine the root cause of this deviation. In particular, the difference in sample size between ESL and EML is examined and modeling shows that this difference is not the controlling factor in determining transformation delay behavior. 相似文献