The results of the investigations on rock mechanics in HDB-9-11 boreholes and update of the rock mechanical model around the Horonobe URL construction area

International Nuclear Information System (INIS)

Sanada, Hiroyuki; Niunoya, Sumio; Matsui, Hiroya

2008-09-01

Horonobe URL (Underground Research Laboratory) Project is conducted at Horonobe-cho, Teshio-gun, Hokkaido. This research report shows the result of the rock mechanical investigations which have been carried out from 2004 to 2005 as a part of the project. The objectives of the rock mechanical investigation are as follows: To obtain the data which were necessary for construction design of URL. To confirm the distribution of rock mechanical properties in and around URL construction area. The results of the investigations are summarized as follows: 1) Variation and values of depth direction of physical and mechanical properties in the laboratory construction area corresponded approximately to the results obtained from the rock mechanical investigations of HDB-1-8. 2) The major redesign had been not had about physical and mechanical properties in the laboratory construction area being able to divide into three zones and length of its own zone in updating rock mechanical model. 3) From the results of initial stress measured by hydraulic fracturing, the results that the direction of the maximum principle stress is E-W was no different from results obtained from the investigations of HDB-1-8, but the magnitude correlation among maximum, minimum principle stress and overburden pressure measured around G.L.-927 m showed different trends compared with the results of HDB-1-8. 4) Diatomaceous mudstone was yielded under isotropic compression. Cam-clay model as constitutive law of diatomaceous mudstone should be used for tunnel excavation analysis. 5) Uniaxial compression strength of rock saturated under saline water is larger than that of saturated under freshwater. Poisson's ratio of rock saturated under saline water is smaller than that of saturated under saline water. 6) The effective confining pressure increases with the equivalent opening width and permeability decreases. 7) The value of principle stress obtained from DSCA method is larger than that obtained from hydraulic

Results of monitoring at Olkiluoto in 2012. Rock mechanics

International Nuclear Information System (INIS)

Johansson, E.; Siren, T.

2014-01-01

The rock mechanics monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The rock mechanics monitoring programme 2012 consisted of seismic measurements, GPS measurements, surface levelling measurements and temperature measurements at Olkiluoto and vicinity and displacement measurements, temperature measurements and visual tunnel observations carried out in the ONKALO. The Posiva's microseismic network consists of 17 seismic stations and 22 triaxial sensors. Six stations are in the ONKALO. In spite of few breaks the network operated continuously and well during 2012. The number of located events was much smaller in 2012 than during the previous years due to the interruption of the excavation. Altogether 337 events were located in the Olkiluoto area of which about half (181) were explosions. Two excavation induced earthquakes were observed at -420 m level and were associated with a known tunnel crosscutting fracture. According to the seismic monitoring the rock mass has been stable in 2012. The local GPS network consists of 19 stations. The whole network was measured twice in 2012. Most of the inner network baselines showed very small motions as in the previous years: 80 % of change rates were smaller than 0.10 mm/a. Roughly one third of the change rates are statistically significant. One baseline was also measured using electronic distance measurements (EDM) and the results fitted well to the times series. The surface levelling network currently consists of 87 fixed measuring points. During 2012 only measuring loops VLJ, ONKALO and Olkiluoto Strait were measured. The results indicated that vertical deformations were small compared to 2011 results. The largest deformations around 0.6 mm upwards existed above the VLJ-repository. The displacement measurements in 2012 consisted of the extensometer measurements in the technical rooms of the ONKALO. Readings were taken continuously once a hour by a

Persistent visual impairment in multiple sclerosis: prevalence, mechanisms and resulting disability.

Science.gov (United States)

Jasse, Laurence; Vukusic, Sandra; Durand-Dubief, Françoise; Vartin, Cristina; Piras, Carolina; Bernard, Martine; Pélisson, Denis; Confavreux, Christian; Vighetto, Alain; Tilikete, Caroline

2013-10-01

The objective of this article is to evaluate in multiple sclerosis (MS) patients the prevalence of persistent complaints of visual disturbances and the mechanisms and resulting functional disability of persistent visual complaints (PVCs). Firstly, the prevalence of PVCs was calculated in 303 MS patients. MS-related data of patients with or without PVCs were compared. Secondly, 70 patients with PVCs performed an extensive neuro-ophthalmologic assessment and a vision-related quality of life questionnaire, the National Eye Institute Visual Functionary Questionnaire (NEI-VFQ-25). PVCs were reported in 105 MS patients (34.6%). Patients with PVCs had more frequently primary progressive MS (30.5% vs 13.6%) and more neuro-ophthalmologic relapses (1.97 vs 1.36) than patients without PVCs. In the mechanisms/disability study, an afferent visual and an ocular-motor pathways dysfunction were respectively diagnosed in 41 and 59 patients, mostly related to bilateral optic neuropathy and bilateral internuclear ophthalmoplegia. The NEI-VFQ 25 score was poor and significantly correlated with the number of impaired neuro-ophthalmologic tests. Our study emphasizes the high prevalence of PVC in MS patients. Regarding the nature of neuro-ophthalmologic deficit, our results suggest that persistent optic neuropathy, as part of the progressive evolution of the disease, is not rare. We also demonstrate that isolated ocular motor dysfunctions induce visual disability in daily life.

Two Mechanisms to Avoid Control Conflicts Resulting from Uncoordinated Intent

Science.gov (United States)

Mishkin, Andrew H.; Dvorak, Daniel L.; Wagner, David A.; Bennett, Matthew B.

2013-01-01

This software implements a real-time access control protocol that is intended to make all connected users aware of the presence of other connected users, and which of them is currently in control of the system. Here, "in control" means that a single user is authorized and enabled to issue instructions to the system. The software The software also implements a goal scheduling mechanism that can detect situations where plans for the operation of a target system proposed by different users overlap and interact in conflicting ways. In such situations, the system can either simply report the conflict (rejecting one goal or the entire plan), or reschedule the goals in a way that does not conflict. The access control mechanism (and associated control protocol) is unique. Other access control mechanisms are generally intended to authenticate users, or exclude unauthorized access. This software does neither, and would likely depend on having some other mechanism to support those requirements.

Interest in the glenoid hull method for analyzing humeral subluxation in primary glenohumeral osteoarthritis.

Science.gov (United States)

Bouacida, Soufyane; Gauci, Marc-Olivier; Coulet, Bertrand; Lazerges, Cyril; Cyteval, Catherine; Boileau, Pascal; Chammas, Michel

2017-07-01

Posterior humeral subluxation is the main cause of failure of total shoulder arthroplasty. We aimed to compare humeral head subluxation in various reference planes and to search for a correlation with retroversion, inclination, and glenoid wear. We included 109 computed tomography scans of primary glenohumeral osteoarthritis and 97 of shoulder problems unrelated to shoulder osteoarthritis (controls); all computed tomography scans were reconstructed in the anatomic scapular plane and the glenoid hull plane that we defined. In both planes, we measured retroversion, inclination, glenohumeral offset (Walch index), and scapulohumeral offset. Retroversion in the scapular plane (Friedman method) was lower than that in the glenoid hull plane for controls and for arthritic shoulders. The threshold of scapulohumeral subluxation was 60% and 65% in the scapular plane and glenoid hull plane, respectively. The mean upward inclination was lower in the scapular plane (Churchill method) than in the glenoid hull plane (Maurer method). In the glenoid hull plane, 35% of type A2 glenoids showed glenohumeral offset greater than 75%, with mean retroversion of 25.6° ± 6° as compared with 7.5° ± 7.2° for the "centered" type A2 glenoids (P hull plane and r = 0.59 in the scapular plane (P hull plane may be more accurate than in the scapular plane. Thus, the glenoid hull method allows for better understanding type B3 of the modified Walch classification. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Fracture-mechanical results of non-destructive testing - function, goals, methods

International Nuclear Information System (INIS)

Herter, K.H.; Kockelmann, H.; Schuler, X.; Waidele, H.

2004-01-01

Non-destructive testing provides data for fracture-mechanical analyses, e.g. defect size and orientation. On the other hand, fracture-mechanical analyses may help to define criteria for non-destructive testing, e.g. sensitivity, inspection intervals and inspection sites. The criteria applied differ as a function of the safety relevance of a component. (orig.) [de

Impact of Prolonged Mechanical Ventilation in Very Low Birth Weight Infants: Results From a National Cohort Study.

Science.gov (United States)

Choi, Young-Bin; Lee, Juyoung; Park, Jisun; Jun, Yong Hoon

2018-03-01

To evaluate the in-hospital consequences of prolonged respiratory support with invasive mechanical ventilation in very low birth weight infants. A cohort study was performed using prospectively collected data from 69 neonatal intensive care units participating in the Korean national registry. In total, 3508 very low birth weight infants born between January 1, 2013 and December 31, 2014 were reviewed. The adjusted hazard ratio for death increased significantly for infants who received mechanical ventilation for more than 2 weeks compared with those were mechanically ventilated for 7 days or less. The individual mortality rate increased after 8 weeks, reaching 50% and 60% at 14 and 16 weeks of cumulative mechanical ventilation, respectively. After adjusting for potential confounders, the cumulative duration of mechanical ventilation was associated with a clinically significant increase in the odds of bronchopulmonary dysplasia and pulmonary hypertension. Mechanical ventilation exposure for longer than 2 weeks, compared with 7 days or less, was associated with retinopathy of prematurity requiring laser coagulation and periventricular leukomalacia. The odds of abnormal auditory screening test results were significantly increased in infants who needed mechanical ventilation for more than 4 weeks. A longer cumulative duration of mechanical ventilation was associated with increased lengths of hospitalization and parenteral nutrition and a higher probability of discharge with poor achievement of physical growth. Although mechanical ventilation is a life-saving intervention for premature infants, these results indicate that it is associated with negative consequences when applied for prolonged periods. Copyright © 2017 Elsevier Inc. All rights reserved.

Results of fracture mechanics tests on PNC SUS 304 plate

International Nuclear Information System (INIS)

Mills, W.J.; James, L.A.; Blackburn, L.D.

1985-08-01

PNC provided SUS 304 plate to be irradiated in FFTF at about 400 0 C to a target fluence of 5 x 10 21 n/cm 2 (E > 0.1 MeV). The actual irradiation included two basically different exposure levels to assure that information would be available for the exposure of interest. After irradiation, tensile properties, fatigue-crack growth rates and J-integral fracture toughness response were determined. These same properties were also measured for the unirradiated material so radiation damage effects could be characterized. This report presents the results of this program. It is expected that these results would be applicable for detailed fracture analysis of reactor components. Recent advances in elastic-plastic fracture mechanics enable reasonably accurate predictions of failure conditions for flawed stainless steel components. Extensive research has focused on the development of J-integral-based engineering approach for assessing the load carrying capacity of low-strength, high-toughness structural materials. Furthermore, Kanninen, et al., have demonstrated that J-integral concepts can accurately predict the fracture response for full-scale cracked structures manufactured from Type 304 stainless steel

[Interactions of DNA bases with individual water molecules. Molecular mechanics and quantum mechanics computation results vs. experimental data].

Science.gov (United States)

Gonzalez, E; Lino, J; Deriabina, A; Herrera, J N F; Poltev, V I

2013-01-01

To elucidate details of the DNA-water interactions we performed the calculations and systemaitic search for minima of interaction energy of the systems consisting of one of DNA bases and one or two water molecules. The results of calculations using two force fields of molecular mechanics (MM) and correlated ab initio method MP2/6-31G(d, p) of quantum mechanics (QM) have been compared with one another and with experimental data. The calculations demonstrated a qualitative agreement between geometry characteristics of the most of local energy minima obtained via different methods. The deepest minima revealed by MM and QM methods correspond to water molecule position between two neighbor hydrophilic centers of the base and to the formation by water molecule of hydrogen bonds with them. Nevertheless, the relative depth of some minima and peculiarities of mutual water-base positions in' these minima depend on the method used. The analysis revealed insignificance of some differences in the results of calculations performed via different methods and the importance of other ones for the description of DNA hydration. The calculations via MM methods enable us to reproduce quantitatively all the experimental data on the enthalpies of complex formation of single water molecule with the set of mono-, di-, and trimethylated bases, as well as on water molecule locations near base hydrophilic atoms in the crystals of DNA duplex fragments, while some of these data cannot be rationalized by QM calculations.

MCPIP1 deficiency in mice results in severe anemia related to autoimmune mechanisms.

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Zhou Zhou

Full Text Available Autoimmune gastritis is an organ-specific autoimmune disease of the stomach associated with pernicious anemia. The previous work from us and other groups identified MCPIP1 as an essential factor controlling inflammation and immune homeostasis. MCPIP1(-/- developed severe anemia. However, the mechanisms underlying this phenotype remain unclear. In the present study, we found that MCPIP1 deficiency in mice resulted in severe anemia related to autoimmune mechanisms. Although MCPIP1 deficiency did not affect erythropoiesis per se, the erythropoiesis in MCPIP1(-/- bone marrow erythroblasts was significantly attenuated due to iron and vitamin B12 (VB12 deficiency, which was mainly resulted from autoimmunity-associated gastritis and parietal cell loss. Consistently, exogenous supplement of iron and VB12 greatly improved the anemia phenotype of MCPIP1(-/- mice. Finally, we have evidence suggesting that autoimmune hemolysis may also contribute to anemia phenotype of MCPIP1(-/- mice. Taken together, our study suggests that MCPIP1 deficiency in mice leads to the development of autoimmune gastritis and pernicious anemia. Thus, MCPIP1(-/- mice may be a good mouse model for investigating the pathogenesis of pernicious anemia and testing the efficacy of some potential drugs for treatment of this disease.

Targeting the epidermal growth factor receptor in radiotherapy: radiobiological mechanisms, preclinical and clinical results

International Nuclear Information System (INIS)

Baumann, Michael; Krause, Mechthild

2004-01-01

Background and purpose: Inhibition of the epidermal growth factor receptor (EGFR) is a fastly developing field in preclinical and clinical cancer research. This review presents the current status of knowledge and discusses radiobiological mechanisms which may underly the efficacy of EGFR inhibitors combined with irradiation. Materials and methods: Preclinical and clinical results on combined targeting of the EGFR and irradiation from the literature and from this laboratory are reviewed. Focus is given to the radiobiological rationale of this approach and to endpoints of experimental radiotherapy. Results: Overexpression of the EGFR is associated with decreased local tumour control after radiotherapy, especially when the overall treatment time is long. Inhibition of the EGFR either alone or in combination with irradiation decreases the growth rate of tumours expressing this receptor. Preclinical data provide proof-of-principle that local tumour control may be improved by combining irradiation with C225 mAb. In a randomised phase III clinical trial, simultaneous irradiation and treatment with the EGFR antibody Cetuximab (Erbitux[reg]; C225) in head and neck cancer patients resulted in significantly improved locoregional tumour control and survival compared to curative irradiation alone. Acute skin reactions increased in the experimental arm. The underlying mechanisms of enhanced radiation effects of combined EGFR inhibition with irradiation and of the partly conflicting results in different studies are poorly understood. There is increasing evidence, that important intertumoral heterogeneity in the response to EGFR inhibition alone and combined with irradiation exists, which appears to be at least partly dependent on specific mutations of the receptor as well as of molecules that are involved in the intracellular signal transduction pathway. Conclusions and outlook: Further investigations at all levels of the translational research chain exploring the mechanisms of

Measurements of entanglement over a kilometric distance to test superluminal models of Quantum Mechanics: preliminary results.

Science.gov (United States)

Cocciaro, B.; Faetti, S.; Fronzoni, L.

2017-08-01

As shown in the EPR paper (Einstein, Podolsky e Rosen, 1935), Quantum Mechanics is a non-local Theory. The Bell theorem and the successive experiments ruled out the possibility of explaining quantum correlations using only local hidden variables models. Some authors suggested that quantum correlations could be due to superluminal communications that propagate isotropically with velocity vt > c in a preferred reference frame. For finite values of vt and in some special cases, Quantum Mechanics and superluminal models lead to different predictions. So far, no deviations from the predictions of Quantum Mechanics have been detected and only lower bounds for the superluminal velocities vt have been established. Here we describe a new experiment that increases the maximum detectable superluminal velocities and we give some preliminary results.

Mitochondrial disorders in progressive muscular dystrophies

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D. A. Kharlamov

2014-01-01

Full Text Available The literature review gives data on the role of mitochondrial disorders in the pathogenesis of different progressive muscular dystrophies. It describes changes in Duchenne, limb-girdle, facial scapulohumeral (Landuzi—Degerina muscular dystrophies. The review is based on both clinical and experimental animal studies. Along with the implication of mitochondria in the pathogenesis of the diseases, it describes muscular dystrophy treatment options compensating for energy disorders and overcoming oxidative stress and mitochondrial dysfunction. Mitochondrial studies in different muscle diseases hand physicians treatment modalities that fail to lead to recovery, but compensate for disorders caused by mutations in the genetic apparatus. 

Reduced left ventricular filling following blood volume extraction does not result in compensatory augmentation of cardiac mechanics.

Science.gov (United States)

Lord, Rachel; MacLeod, David; George, Keith; Oxborough, David; Shave, Rob; Stembridge, Mike

2018-04-01

What is the central question of this study? A reduction in left ventricular (LV) filling, and concomitant increase in heart rate, augments LV mechanics to maintain stroke volume (SV); however, the impact of reduced LV filling in isolation on SV and LV mechanics is currently unknown. What is the main finding and its importance? An isolated decrease in LV filling did not provoke a compensatory increase in mechanics to maintain SV; in contrast, LV mechanics and SV were reduced. These data indicate that when LV filling is reduced without changes in heart rate, LV mechanics do not compensate to maintain SV. An acute non-invasive reduction in preload has been shown to augment cardiac mechanics to maintain stroke volume and cardiac output. Such interventions induce concomitant changes in heart rate, whereas blood volume extraction reduces preload without changes in heart rate. Therefore, the purpose of this study was to determine whether a preload reduction in isolation resulted in augmented stroke volume achieved via enhanced cardiac mechanics. Nine healthy volunteers (four female, age 29 ± 11 years) underwent echocardiography for the assessment of left ventricular (LV) volumes and mechanics in a supine position at baseline and end extraction after the controlled removal of 25% of total blood volume (1062 ± 342 ml). Arterial blood pressure was monitored continuously by a pressure transducer attached to an indwelling radial artery catheter. Heart rate and total peripheral resistance were unchanged from baseline to end extraction, but systolic blood pressure was reduced (from 148 to 127 mmHg). From baseline to end extraction there were significant reductions in left ventricular end-diastolic volume (from 89 to 71 ml) and stroke volume (from 56 to 37 ml); however, there was no change in LV twist, basal or apical rotation. In contrast, LV longitudinal strain (from -20 to -17%) and basal circumferential strain (from -22 to -19%) were significantly reduced from

Statistical mechanics of few-particle systems: exact results for two useful models

Science.gov (United States)

Miranda, Enrique N.

2017-11-01

The statistical mechanics of small clusters (n ˜ 10-50 elements) of harmonic oscillators and two-level systems is studied exactly, following the microcanonical, canonical and grand canonical formalisms. For clusters with several hundred particles, the results from the three formalisms coincide with those found in the thermodynamic limit. However, for clusters formed by a few tens of elements, the three ensembles yield different results. For a cluster with a few tens of harmonic oscillators, when the heat capacity per oscillator is evaluated within the canonical formalism, it reaches a limit value equal to k B , as in the thermodynamic case, while within the microcanonical formalism the limit value is k B (1-1/n). This difference could be measured experimentally. For a cluster with a few tens of two-level systems, the heat capacity evaluated within the canonical and microcanonical ensembles also presents differences that could be detected experimentally. Both the microcanonical and grand canonical formalism show that the entropy is non-additive for systems this small, while the canonical ensemble reaches the opposite conclusion. These results suggest that the microcanonical ensemble is the most appropriate for dealing with systems with tens of particles.

The deformable secondary mirror of VLT: final electro-mechanical and optical acceptance test results

Science.gov (United States)

Briguglio, Runa; Biasi, Roberto; Xompero, Marco; Riccardi, Armando; Andrighettoni, Mario; Pescoller, Dietrich; Angerer, Gerald; Gallieni, Daniele; Vernet, Elise; Kolb, Johann; Arsenault, Robin; Madec, Pierre-Yves

2014-07-01

The Deformable Secondary Mirror (DSM) for the VLT ended the stand-alone electro-mechanical and optical acceptance process, entering the test phase as part of the Adaptive Optics Facility (AOF) at the ESO Headquarter (Garching). The VLT-DSM currently represents the most advanced already-built large-format deformable mirror with its 1170 voice-coil actuators and its internal metrology based on co-located capacitive sensors to control the shape of the 1.12m-diameter 2mm-thick convex shell. The present paper reports the final results of the electro-mechanical and optical characterization of the DSM executed in a collaborative effort by the DSM manufacturing companies (Microgate s.r.l. and A.D.S. International s.r.l.), INAF-Osservatorio Astrofisico di Arcetri and ESO. The electro-mechanical acceptance tests have been performed in the company premises and their main purpose was the dynamical characterization of the internal control loop response and the calibration of the system data that are needed for its optimization. The optical acceptance tests have been performed at ESO (Garching) using the ASSIST optical test facility. The main purpose of the tests are the characterization of the optical shell flattening residuals, the corresponding calibration of flattening commands, the optical calibration of the capacitive sensors and the optical calibration of the mirror influence functions.

Results of Monitoring at Olkiluoto in 2005. Rock Mechanics

International Nuclear Information System (INIS)

Riikonen, S.

2006-08-01

Programme of Monitoring (Posiva 2003 b) was introduced to study Olkiluoto investigation are both during and following the excavation of underground test facility, ONKALO. Programme consists of four main headings: rock mechanics, hydrology and hydrogeology, geochemistry and other types of disturbance. Monitoring programme in year 2005 consist of three fields of research: microseismic measurements, GPS measurements and precise levelling. This report presents Posiva's rock mechanical monitoring programme results from the year 2005. Report has been composed from annual reports of microseismic measurements, GPS measurements and precise levelling by Sanna Riikonen. In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. This report gives the results of microseismic monitoring during the year 2005. Also the changes in the structure and the operation procedure of the network are described. The network has operated nearly continuously. The total duration of network failures has been about 8 hours. Altogether 2159 events have been located in the Olkiluoto area, in reported time period. The magnitudes of the observed events range from ML = -2.1to ML = 1.6 (ML = magnitude in local Richter's scale). Most of them are explosions. Three of the observed events are be classified as microearthquakes. Evidence of activity that would has influence on the safety of the ONKALO, have not found. The GPS based deformation studies has been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. Twenty GPS measurement campaigns have been carried out at Olkiluoto since 1995. According to the time series of the GPS results 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.22 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. The local velocity components are small but

Experimental results on mechanisms of action of electrical neuromodulation in chronic urinary retention.

Science.gov (United States)

Schultz-Lampel, D; Jiang, C; Lindström, S; Thüroff, J W

1998-01-01

Sacral foramen neuromodulation--initially applied for the treatment of urinary incontinence--has proved to be effective in patients with chronic urinary retention. Thus far, the underlying neurophysiological mechanisms have not been elucidated. In an experimental study on the neurophysiological basis of sacral neurostimulation, one objective was to investigate the mechanisms responsible for initiation of micturition in chronic urinary retention. In ten female cats anesthetized with alpha-chloralose the clinical situation of sacral foramen stimulation was experimentally reproduced by isolated S2 nerve stimulation after L6-S3 laminectomy. Stimulation responses were recorded from the bladder, peripheral nerves, and striated muscles of the foot and pelvic floor. The effect of sudden cessation of prolonged S2 stimulation, during which the bladder was completely inhibited, was evaluated in 70 stimulation sequences in 5 cats. Sacral nerve stimulation induced excitatory and inhibitory effects on the bladder, depending on the frequency and intensity of stimulation. With unilateral S2 stimulation, bladder excitation was best at frequencies of 2-5 Hz and at intensities ranging between 0.8 and 1.4 times the threshold for the M-response of the foot muscle. Inhibition was the dominating effect at frequencies of 7-10 Hz and at intensities exceeding 1.4 times the threshold. Prolonged S2 stimulation above the threshold produced complete bladder inhibition during stimulation but induced strong bladder contractions after sudden interruption of stimulation, with amplitudes being significantly higher than that of spontaneous contractions preceding the stimulation. These results confirm the hypothesis of a "rebound" phenomenon as the mechanism of action for induction of spontaneous voiding in patients with chronic urinary retention.

Study of Finite Element Number Influence over the Obtained Results in Finite Element Analyses of a Mechanical Structure

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Ana-Maria Budai

2013-05-01

Full Text Available This paper present the results of a study that was made to establish the influence of finite element number used to determined the real load of a structure. Actually, the study represent a linear static analyze for a link gear control mechanism of a Kaplan turbine. The all analyze was made for the normal condition of functioning having like final scope to determine de life time duration of mentioned mechanism.

Thermo-mechanical behavior of retro-reflector and resulting parallelism error of laser beams for Wendelstein 7-X interferometer

International Nuclear Information System (INIS)

Peng, X.B.; Hirsch, M.; Köppen, M.; Fellinger, J.; Bykov, V.; Schauer, F.; Vliegenthart, W.

2014-01-01

Highlights: • The criterion for thermo-mechanical design of W7-X interferometer retro-reflector. • Thermo-mechanical analysis of retro-reflector with two different methods. • The most flexible part in the retro-reflector is spring washer. • Calculation of parallelism error between the incoming and reflected laser beams. • The parallelism error is much lower than the design limit 28 arcs. - Abstract: A 10 channels interferometer will be used in the Wendelstein 7-X (W7-X) for plasma density control and density profile tracking with laser beams passing through the plasma. Due to complex shape of non-planar modular coils and divertor structure, there are no large poloidally opposite ports on the plasma vessel (PV). Therefore 10 in-vessel Corner Cube Retro-reflectors (CCRs) will be used. The CCRs are integrated in the water cooled heat shield and exposed directly to thermal loads from plasma radiation. Thermo-mechanical issues are very important for the design of the CCR because deformation and flatness as well as mutual angles of the three reflecting surfaces would affect the parallelism of the laser beams and the functionality of the interferometer. Intensive work has been done to explore a suitable design for the CCR concerning thermo-mechanical behavior. Previous studies Ye et al. (2008, 2009) and Köppen et al. (2011) focused on structural optimization to decrease thermal stress in the reflecting plates under the thermal loads, and on computation and check of curvature radii of the deformed reflecting surfaces with the design criterion that the curvature radius must be bigger than 200 m. The paper presents detailed thermo-mechanical analysis of the current improved CCR under thermal loads and bolt preloads. The results of the thermo-mechanical analysis were used for the study of the resulting parallelism error of the laser beams with newly developed and more reasonable design criterion

Thermo-mechanical behavior of retro-reflector and resulting parallelism error of laser beams for Wendelstein 7-X interferometer

Energy Technology Data Exchange (ETDEWEB)

Peng, X.B., E-mail: pengxb@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031 Hefei Anhui (China); Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Hirsch, M.; Köppen, M.; Fellinger, J.; Bykov, V.; Schauer, F. [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Vliegenthart, W. [TNO, Stieltjesweg 1, P.O. Box 2600, 2628 CK Delft (Netherlands)

2014-04-15

Highlights: • The criterion for thermo-mechanical design of W7-X interferometer retro-reflector. • Thermo-mechanical analysis of retro-reflector with two different methods. • The most flexible part in the retro-reflector is spring washer. • Calculation of parallelism error between the incoming and reflected laser beams. • The parallelism error is much lower than the design limit 28 arcs. - Abstract: A 10 channels interferometer will be used in the Wendelstein 7-X (W7-X) for plasma density control and density profile tracking with laser beams passing through the plasma. Due to complex shape of non-planar modular coils and divertor structure, there are no large poloidally opposite ports on the plasma vessel (PV). Therefore 10 in-vessel Corner Cube Retro-reflectors (CCRs) will be used. The CCRs are integrated in the water cooled heat shield and exposed directly to thermal loads from plasma radiation. Thermo-mechanical issues are very important for the design of the CCR because deformation and flatness as well as mutual angles of the three reflecting surfaces would affect the parallelism of the laser beams and the functionality of the interferometer. Intensive work has been done to explore a suitable design for the CCR concerning thermo-mechanical behavior. Previous studies Ye et al. (2008, 2009) and Köppen et al. (2011) focused on structural optimization to decrease thermal stress in the reflecting plates under the thermal loads, and on computation and check of curvature radii of the deformed reflecting surfaces with the design criterion that the curvature radius must be bigger than 200 m. The paper presents detailed thermo-mechanical analysis of the current improved CCR under thermal loads and bolt preloads. The results of the thermo-mechanical analysis were used for the study of the resulting parallelism error of the laser beams with newly developed and more reasonable design criterion.

Results of Monitoring at Olkiluoto in 2010. Rock Mechanics

Energy Technology Data Exchange (ETDEWEB)

Lahti, M [ed.; Siren, T

2011-12-15

The rock mechanical monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The construction of ONKALO is not expected to induce large-scale movements of the rock blocks or affect the rate of isostatic uplift but the evaluation of any tectonic events is important for the safety assessment. The monitoring consists of seismic measurements, GPS measurements and precise levelling campaigns at Olkiluoto and vicinity and extensometer and convergence measurements carried out in ONKALO. Posiva established a local seismic network of six stations on the island of Olkiluoto in 2002. After that the number of seismic stations has increased gradually. In 2010 the permanent seismic network consists of 15 seismic stations and 20 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during 2010.

Results of Monitoring at Olkiluoto in 2010. Rock Mechanics

International Nuclear Information System (INIS)

Lahti, M.; Siren, T.

2011-12-01

The rock mechanical monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The construction of ONKALO is not expected to induce large-scale movements of the rock blocks or affect the rate of isostatic uplift but the evaluation of any tectonic events is important for the safety assessment. The monitoring consists of seismic measurements, GPS measurements and precise levelling campaigns at Olkiluoto and vicinity and extensometer and convergence measurements carried out in ONKALO. Posiva established a local seismic network of six stations on the island of Olkiluoto in 2002. After that the number of seismic stations has increased gradually. In 2010 the permanent seismic network consists of 15 seismic stations and 20 triaxial sensors. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semiregional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale inside that area. The smaller target area is called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. It is assumed that all the expected excavation induced events occur within this volume. At the moment the seismic ONKALO block includes ten seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. This report gives the results of microseismic monitoring during 2010

Towards a quantitative definition of mechanical units: New techniques and results from an outcropping deep water succession.

NARCIS (Netherlands)

Bertotti, G.V.; Hardebol, N.; Taal-Van Koppen, J.; Luthi, S.

2007-01-01

The physical properties of reservoirs are strongly influenced by distributed fracture fields. Outcrop studies are commonly used to determine them but have provided unsatisfactory results because the definition of mechanical units, i.e., (groups of) layers displaying homogeneous fracture patterns, is

Mechanisms of gas retention and release: Experimental results for Hanford waste tanks 241-AW-101 and 241-AN-103

Energy Technology Data Exchange (ETDEWEB)

Rassat, S.D.; Gauglitz, P.A.; Bredt, P.R.; Mahoney, L.A.; Forbes, S.V.; Tingey, S.M.

1997-09-01

The 177 storage tanks at Hanford contain a vast array of radioactive waste forms resulting, primarily, from nuclear materials processing. Through radiolytic, thermal, and other decomposition reactions of waste components, gaseous species including hydrogen, ammonia, and the oxidizer nitrous oxide are generated within the waste tanks. Many of these tanks are known to retain and periodically release quantities of these flammable gas mixtures. The primary focus of the Flammable Gas Project is the safe storage of Hanford tank wastes. To this end, we strive to develop an understanding of the mechanisms of flammable gas retention and release in Hanford tanks through laboratory investigations on actual tank wastes. These results support the closure of the Flammable Gas Unreviewed Safety Question (USQ) on the safe storage of waste tanks known to retain flammable gases and support resolution of the broader Flammable Gas Safety Issue. The overall purpose of this ongoing study is to develop a comprehensive and thorough understanding of the mechanisms of flammable gas retention and release. The first objective of the current study was to classify bubble retention and release mechanisms in two previously untested waste materials from Tanks 241-AN-103 (AN-103) and 241-AW-101 (AW-101). Results were obtained for retention mechanisms, release characteristics, and the maximum gas retention. In addition, unique behavior was also documented and compared with previously studied waste samples. The second objective was to lengthen the duration of the experiments to evaluate the role of slowing bubble growth on the retention and release behavior. Results were obtained for experiments lasting from a few hours to a few days.

Mechanisms of gas retention and release: Experimental results for Hanford waste tanks 241-AW-101 and 241-AN-103

International Nuclear Information System (INIS)

Rassat, S.D.; Gauglitz, P.A.; Bredt, P.R.; Mahoney, L.A.; Forbes, S.V.; Tingey, S.M.

1997-09-01

The 177 storage tanks at Hanford contain a vast array of radioactive waste forms resulting, primarily, from nuclear materials processing. Through radiolytic, thermal, and other decomposition reactions of waste components, gaseous species including hydrogen, ammonia, and the oxidizer nitrous oxide are generated within the waste tanks. Many of these tanks are known to retain and periodically release quantities of these flammable gas mixtures. The primary focus of the Flammable Gas Project is the safe storage of Hanford tank wastes. To this end, we strive to develop an understanding of the mechanisms of flammable gas retention and release in Hanford tanks through laboratory investigations on actual tank wastes. These results support the closure of the Flammable Gas Unreviewed Safety Question (USQ) on the safe storage of waste tanks known to retain flammable gases and support resolution of the broader Flammable Gas Safety Issue. The overall purpose of this ongoing study is to develop a comprehensive and thorough understanding of the mechanisms of flammable gas retention and release. The first objective of the current study was to classify bubble retention and release mechanisms in two previously untested waste materials from Tanks 241-AN-103 (AN-103) and 241-AW-101 (AW-101). Results were obtained for retention mechanisms, release characteristics, and the maximum gas retention. In addition, unique behavior was also documented and compared with previously studied waste samples. The second objective was to lengthen the duration of the experiments to evaluate the role of slowing bubble growth on the retention and release behavior. Results were obtained for experiments lasting from a few hours to a few days

Exact results in nonequilibrium statistical mechanics: Formalism and applications in chemical kinetics and single-molecule free energy estimation

Science.gov (United States)

Adib, Artur B.

In the last two decades or so, a collection of results in nonequilibrium statistical mechanics that departs from the traditional near-equilibrium framework introduced by Lars Onsager in 1931 has been derived, yielding new fundamental insights into far-from-equilibrium processes in general. Apart from offering a more quantitative statement of the second law of thermodynamics, some of these results---typified by the so-called "Jarzynski equality"---have also offered novel means of estimating equilibrium quantities from nonequilibrium processes, such as free energy differences from single-molecule "pulling" experiments. This thesis contributes to such efforts by offering three novel results in nonequilibrium statistical mechanics: (a) The entropic analog of the Jarzynski equality; (b) A methodology for estimating free energies from "clamp-and-release" nonequilibrium processes; and (c) A directly measurable symmetry relation in chemical kinetics similar to (but more general than) chemical detailed balance. These results share in common the feature of remaining valid outside Onsager's near-equilibrium regime, and bear direct applicability in protein folding kinetics as well as in single-molecule free energy estimation.

Methods for improving mechanical properties of partially stabilized zirconia and the resulting product

International Nuclear Information System (INIS)

Aronov, V.A.

1987-01-01

A method for improving mechanical surface properties of a rigid body comprising partially stabilized zirconia as a constituent is described comprising the following steps: (i) providing a rigid body having an exposed surface and an interior volume; (ii) subjecting the exposed surface region of partially stabilized zirconia to external heating to heat the exposed surface region to 1100 0 C-1600 0 C without heating the interior volume above 500 0 C-800 0 C; and (iii) cooling the rigid body to a temperature of less than 500 0 C to cause a portion of the exposed surface region to transform from the tetragonal lattice modification to the monoclinic lattice modification, thereby creating a compressive stress field in the exposed surface region and improving the mechanical surface properties of the exposed surface region. In a ceramic body comprising a first exposed region of a partially stabilized zirconia, and a second region of a partially stabilized zirconia at an interior portion of the ceramic body, the improvement is described comprising the ceramic body having in the first, exposed region a greater percentage of the monoclinic lattice modification than in the second region; having in the first, exposed region 5 percent to 100 percent in the monoclinic lattice modification; and having a molded surface finish in the first, exposed region; the first, exposed region being subjected to a compressive field resulting from the greater percentage of the monoclinic lattice modification

Angularly Deformed Special Relativity and its Results for Quantum Mechanics

OpenAIRE

Glinka, Lukasz Andrzej

2015-01-01

In this paper, the deformed Special Relativity, which leads to an essentially new theoretical context of quantum mechanics, is presented. The formulation of the theory arises from a straightforward analogy with the Special Relativity, but its foundations are laid through the hypothesis on breakdown of the velocity-momentum parallelism which affects onto the Einstein equivalence principle between mass and energy of a relativistic particle. Furthermore, the derivation is based on the technique ...

Results of laboratory and in-situ measurements for the description of coupled thermo-hydro-mechanical processes in clays

Energy Technology Data Exchange (ETDEWEB)

Goebel, Ingeborg; Alheid, Hans-Joachim [BGR Hannover, Stilleweg 2, D-30655 Hannover (Germany); Jockwer, Norbert [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) mbH, Theodor-Heuss-Str. 4, 38122 Braunschweig (Germany); Mayor, Juan Carlos [ENRESA, Emilio Vargas 7, E-Madrid (Spain); Garcia-Sineriz, Jose Luis [AITEMIN, c/ Alenza, 1 - 28003 Madrid (Spain); Alonso, Eduardo [International Center for Numerical Methods in Engineering, CIMNE, Edificio C-1, Campus Norte UPC, C/Gran Capitan, s/n, 08034 Barcelona (Spain); Weber, Hans Peter [NAGRA, Hardstrasse 73, CH-5430 Wettingen (Switzerland); Ploetze, Michael [ETHZ, Eidgenoessische Technische Hochschule Zuerich, ETH Zentrum, HG Raemistrasse 101, CH-8092 Zuerich (Switzerland); Klubertanz, Georg [COLENCO Power Engineering Ltd, CPE, Taefern Str. 26, 5405 Baden-Daettwil (Switzerland); Ammon, Christian [Rothpletz, Lienhard, Cie AG, Schifflaendestrasse 35, 5001 Aarau (Switzerland)

2004-07-01

The Heater Experiment at the Mont Terri Underground Laboratory aims at producing a validated model of thermo-hydro-mechanically (THM) coupled processes. The experiment consists of an engineered barrier system where in a vertical borehole, a heater is embedded in bentonite blocks, surrounded by the host rock, Opalinus Clay. The experimental programme comprises permanent monitoring before, during, and after the heating phase, complemented by geotechnical, hydraulic, and seismic in-situ measurements as well as laboratory analyses of mineralogical and rock mechanics properties. After the heating, the experiment was dismantled for further investigations. Major results of the experimental findings are outlined. (authors)

Modeling and Control Methods for Supporting Scapulohumeral Rhythm with a Robotic Exoskeleton

Data.gov (United States)

National Aeronautics and Space Administration — Extravehicular activities (EVA), which are activities that require a crew member to leave the spacecraft, are a key component of many missions and require a...

VUV treatment combined with mechanical strain of stretchable polymer foils resulting in cell alignment

Energy Technology Data Exchange (ETDEWEB)

Barb, R.-A. [Institute of Applied Physics, Johannes Kepler University Linz (Austria); Magnus, B. [Innovacell Biotechnologie AG, Innsbruck (Austria); Innerbichler, S. [Innerbichler GmbH, Breitenbach am Inn (Austria); Greunz, T. [CDL-MS-MACH, Johannes Kepler University Linz (Austria); Wiesbauer, M. [Institute of Applied Physics, Johannes Kepler University Linz (Austria); Marksteiner, R. [Innovacell Biotechnologie AG, Innsbruck (Austria); Stifter, D. [CDL-MS-MACH, Johannes Kepler University Linz (Austria); Heitz, J., E-mail: johannes.heitz@jku.at [Institute of Applied Physics, Johannes Kepler University Linz (Austria)

2015-01-15

Highlights: • Elastic polyurethane (PU) foils were exposed to the vacuum-UV in reactive atmosphere. • The photomodification resulted in improved cytocompatibilty. • Parallel microgrooves formed on the irradiated PU surfaces after strong elongation. • Cells seeded onto microgrooves aligned their shapes in the direction of the grooves. • Elongation occurred also for cells on PU subjected to cyclic mechanical stretching. - Abstract: Cell-alignment along a defined direction can have a direct effect on the cell functionality and differentiation. Oriented micro- or nanotopographic structures on cell culture substrates can induce cell-alignment. Surface chemistry, wettability, and stiffness of the substrate are also important material features as they strongly influence the cell–substrate interactions. For improved bio-compatibility, highly elastic polyurethane (PU) foils were exposed to the vacuum-UV (VUV) light of a Xe{sub 2}{sup *} excimer lamp at 172 nm in a nitrogen containing atmosphere (N{sub 2} or NH{sub 3}). The irradiation resulted in a change in the chemical surface composition. Additionally, the formation of regular parallel microgrooves was observed on the irradiated surfaces after strong uni-axial deformation (i.e., more than about 50% strain) of the photo-modified PU foils. Cell seeding experiments demonstrated that the VUV modified polymer foils strongly enhance cell adhesion and proliferation. Cells seeded onto microgrooves aligned their shapes and elongated in the direction of the grooves. A similar effect was observed for cells seeded on photo-modified PU foils subjected to cyclic mechanical stretching at lower strain levels (i.e., typically 10% strain) without groove-formation. The cells had also here an elongated shape, however they not always align in a defined direction relative to the stretching.

Report on result 1998. Research and development on fusion area. Part 3 (biomolecular mechanism and design); 1998 nendo seika hokokusho. Yugo ryoiki kenkyu kaihatsu daisan bunsatsu (bimolecular mechanism and design)

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

An organism is a molecular mechanical system consisting of nucleic acid, peptide and protein having a self-forming and a self-repairing function. For the purpose of creating cells, tissues and molecular mechanism alternating these biological functions, their basic technology was developed. Concretely, studies were made on three-dimensional cellular structural module engineering and biomolecular mechanism and design. Studies on biological soft tissue resulted in success by giving atmospheric glow discharge treatment to the inner surface of a tubular PVC. An artificial vitreous body was created using PVA hydrogels. In addition, liver cells were successfully cultured for the first time in the world. Studies on biological hard tissue revealed that osteopontin plays a role of a trigger for the initial differentiation of the osteoblast cell. Further, a basic experiment was carried out on the initial response of the cartilage cell. In the research on the molecular mechanism, examination was made on the mechanism of a double-head molecular motor. Examination was also made on the adjustment of the hydrogenase LB film as an electricity/hydrogen energy conversion element and on the biomolecular mechanism and design. (NEDO)

Long-term aging of cast stainless steels: Mechanisms and resulting properties

International Nuclear Information System (INIS)

Chopra, O.K.; Chung, H.M.

1988-01-01

Mechanical property data are presented from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 450, 400, 350, 320 and 290 deg. C. The results indicate that thermal aging increases the tensile strength and decreases the impact energy, J IC , and tearing modules of the steels. Also, the ductile-to-brittle transition curve shifts to higher temperatures. The ferrite content and concentration of carbon in the steel have a strong effect on the overall process of low-temperature embrittlement. The low-carbon CF-3 steels are the most resistant and the molybdenum-containing high-carbon CF-8M steels are the most susceptible to low-temperature embrittlement. Microstructural data indicate that three processes contribute to embrittlement of cast stainless steels, viz., Cr-rich α' and G-phase precipitation in the ferrite, and carbide precipitation on the austenite/ferrite phase boundary. The influence of nitrogen content and ferrite distribution on loss of toughness are discussed. The data also indicate that existing correlations do not accurately represent the embrittlement behavior over the temperature range 280-450 deg. C, i.e., extrapolation of high temperature data to reactor temperatures may not be valid for some compositions of cast stainless steel. (author)

Missed aortic valve endocarditis resulting in complete atrioventricular block and redo mechanical valve replacement.

Science.gov (United States)

Harky, Amer; Garner, Megan; Popa, Miruna; Shipolini, Alex

2017-08-03

Infective endocarditis is a rare disease associated with high morbidity and mortality. As a result, early diagnosis and prompt antibiotic treatment with or without surgical intervention is crucial in the management of such condition.We report a case of missed infective endocarditis of the aortic valve. The patient underwent mechanical aortic valve replacement, with the native valve being sent for histopathological examination. On re-admission 16 months later, he presented with syncope, shortness of breathing and complete heart block. On review of the histopathology of native aortic valve, endocarditis was identified which had not been acted on. The patient underwent redo aortic valve replacement for severe aortic regurgitation.We highlight the importance of following up histopathological results as well as the need for multidisciplinary treatment of endocarditis with a combination of surgical and antibiotic therapy. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Analysis and evaluation of the result of 1995`s the mechanization program

Energy Technology Data Exchange (ETDEWEB)

Kim, Young Shik; Lee, Kyung Woon; Kim, Oak Hwan; Kim, Dae Kyung [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

1996-12-01

The reducing coal market has been enforcing the coal industry to make exceptional rationalization and restructuring efforts since the end of the eighties. To the competition from crude oil and natural gas has been added the growing pressure from rising wages and rising production cost as the workings get deeper. To improve the competitive position of the coal mines against oil and gas through cost reduction, studies to improve mining system have been carried out. The production of 1995 amounted to 5,719 thousand tons which is less than the last year`s production by 1,719 thousand tons. The investment put for the coal mining mechanization totaled 7,478 million won consisting of 4,176 million won of government subsidy and 3,302 million won of company`s own capital. By increasing mechanization rate from 72 % of the previous year to 75 % and overall O.M.S. from 1.63 ton/man{center_dot}shift to 1.68 ton/man{center_dot} shift the mechanization program got 218.0 billion won of returns compared to the base year 1980 which can be broken down as follows : 1) 89.3 billion won from increase in productivity, 2) 22.0 billion won from increase in calorific value, 3) 5.4 billion won from increase in recovery rate, 4) 101.3 billion won from reduction in accident rate. (author). tabs., 5 figs.

The results of experimental studies of VLF–ULF electromagnetic emission by rock samples due to mechanical action

OpenAIRE

A. A. Panfilov

2013-01-01

The paper presents the results of laboratory experiments on electromagnetic emission excitation (electric component of electromagnetic field) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, cha...

Cocaine smuggling in the gastrointestinal tract resulting in mechanical pylorostenosis.

Science.gov (United States)

Sein Anand, Jacek; Chodorowski, Zygmunt; Masal, Andrzej; Nowak-Banasik, Livia

2005-01-01

A 45-year-old male, body packer, who confessed to have swallowed 44 packages of cocaine in a total dose of approx. 360 g, was admitted to hospital because of clinical signs of acute intoxication with cocaine followed by ileus. The emergency surgical gastrotomy was initiated, and the conglomerate of Scotch tape and packages with cocaine were removed. Small rupture of one package of cocaine in a body packer stomach caused acute poisoning with cocaine, confirmed additionally by the presence of its metabolites in the urine. Mechanical pylorostenosis provoked by cocaine packages required emergency surgical operation.

Influence of Marker Movement Errors on Measuring 3 Dimentional Scapular Position and Orientation

Directory of Open Access Journals (Sweden)

Afsoun Nodehi-Moghaddam

2003-12-01

Full Text Available Objective: Scapulothoracic muscles weakness or fatique can result in abnormal scapular positioning and compromising scapulo-humeral rhythm and shoulder dysfunction .The scapula moves in a -3 Dimentional fashion so the use of 2-Dimentional Techniques cannot fully capture scapular motion . One of approaches to positioining markers of kinematic systems is to mount each marker directly on the skin generally over a bony anatomical landmarks . Howerer skin movement and Motion of underlying bony structures are not Necessaritly identical and substantial errors may be introduced in the description of bone movement when using skin –mounted markers. evaluation of Influence of marker movement errors on 3-Dimentional scapular position and orientation. Materials & Methods: 10 Healthy subjects with a mean age 30.50 participated in the study . They were tested in three sessions A 3-dimentiional electro mechanical digitizer was used to measure scapular position and orientation measures were obtained while arm placed at the side of the body and elevated 45٫90٫120 and full Rang of motion in the scapular plane . At each test positions six bony landmarks were palpated and skin markers were mounted on them . This procedure repeated in the second test session in third session Removal of markers was not performed through obtaining entire Range of motion after mounting the markers . Results: The intraclass correlation coefficients (ICC for scapulor variables were higher (0.92-0.84 when markers were replaced and re-mounted on bony landmarks with Increasing the angle of elevation. Conclusion: our findings suggested significant markers movement error on measuring the upward Rotation and posterior tilt angle of scapula.

An Approach to Implementing A Threshold Adjusting Mechanism in Very Complex Negotiations : A Preliminary Result

OpenAIRE

Fujita, Katsuhide; Ito, Takayuki; Hattori, Hiromitsu; Klein, Mark

2007-01-01

In this paper, we propose a threshold adjusting mechanism in very complex negotiations among software agents. The proposed mechanism can facilitate agents to reach an agreement while keeping their private information as much as possible. Multi-issue negotiation protocols have been studied widely and represent a promising field since most negotiation problems in the real world involve interdependent multiple issues. We have proposed negotiation protocols where a bidding-based mechanism is used...

Mechanical Behavior of Nanostructured and Ultrafine Grained Materials under Shock Wave Loadings. Experimental Data and Results of Computer Simulation.

Science.gov (United States)

Skripnyak, Vladimir

2011-06-01

Features of mechanical behavior of nanostructured (NS) and ultrafine grained (UFG) metal and ceramic materials under quasistatic and shock wave loadings are discussed in this report. Multilevel models developed within the approach of computational mechanics of materials were used for simulation mechanical behavior of UFG and NS metals and ceramics. Comparisons of simulation results with experimental data are presented. Models of mechanical behavior of nanostructured metal alloys takes into account a several structural factors influencing on the mechanical behavior of materials (type of a crystal lattice, density of dislocations, a size of dislocation substructures, concentration and size of phase precipitation, and distribution of grains sizes). Results show the strain rate sensitivity of the yield stress of UFG and polycrystalline alloys is various in a range from 103 up to 106 1/s. But the difference of the Hugoniot elastic limits of a UFG and coarse-grained alloys may be not considerable. The spall strength, the yield stress of UFG and NS alloys are depend not only on grains size, but a number of factors such as a distribution of grains sizes, a concentration and sizes of voids and cracks, a concentration and sizes of phase precipitation. Some titanium alloys with grain sizes from 300 to 500 nm have the quasi-static yield strength and the tensile strength twice higher than that of coarse grained counterparts. But the spall strength of the UFG titanium alloys is only 10 percents above than that of coarse grained alloys. At the same time it was found the spall strength of the bulk UFG aluminium and magnesium alloys with precipitation strengthening is essentially higher in comparison of coarse-grained counterparts. The considerable decreasing of the strain before failure of UFG alloys was predicted at high strain rates. The Hugoniot elastic limits of oxide nanoceramics depend not only on the porosity, but also on sizes and volume distribution of voids.

High mechanical advantage design of six-bar Stephenson mechanism for servo mechanical presses

Directory of Open Access Journals (Sweden)

Jianguo Hu

2016-06-01

Full Text Available This article proposed a two-phase design scheme of Stephenson six-bar working mechanisms for servo mechanical presses with high mechanical advantage. In the qualitative design phase, first, a Stephenson six-bar mechanism with a slide was derived from Stephenson six-bar kinematic chains. Second, based on the instant center analysis method, the relationship between mechanical advantage and some special instant centers was founded, and accordingly a primary mechanism configuration with high mechanical advantage was designed qualitatively. Then, a parameterized prototype model was established, and the influences of design parameters toward slide kinematical characteristics were analyzed. In the quantitative design phase, a multi-objective optimization model, aiming at high mechanical advantage and dwelling characteristics, was built, and a case design was done to find optimal dimensions. Finally, simulations based on the software ADAMS were conducted to compare the transmission characteristics of the optimized working mechanism with that of slide-crank mechanism and symmetrical toggle mechanism, and an experimental press was made to validate the design scheme. The simulation and experiment results show that, compared with general working mechanisms, the Stephenson six-bar working mechanism has higher mechanical advantage and better dwelling characteristics, reducing capacities and costs of servo motors effectively.

Development and chromosome mechanics in nematodes: Results from IML-1

Science.gov (United States)

Nelson, G. A.; Schubert, W. W.; Kazarians, G. A.; Richards, G. F.

1994-01-01

A subset of the Caenorhabditis elegans nematodes flown aboard Biorack on IML-1 was analyzed for the fidelity of development and the mechanics of chromosomes at meiosis. To assess meiosis, mutant worms marked at two linked or unlinked loci were inoculated as heterozygous hermaphrodites and allowed to self fertilize. Mendelian segregation ratios and recombination frequency were measured for offspring produced at 1XG or in microgravity. To assess development, worms and embryos were fixed and stained with the DNA dye, Diamidinophenolindole (DAPI), or antibodies specific for antigens expressed in germ cells, pharyngeal and body wall muscles, and gut cells. The distribution of cytoplasmic determinants, cell nuclei counts and positions were scored to assess symmetry relations and anatomical features.

Superheater fireside corrosion mechanisms in MSWI plants: Lab-scale study and on-site results

Energy Technology Data Exchange (ETDEWEB)

Brossard, J.M.; Chaucherie, X.; Nicol, F. [Veolia Environnement R and D, Zone Portuaire de Limay, 291 Avenue Dreyfous Ducas, Limay 78520 (France); Diop, I. [Veolia Environnement R and D, Zone Portuaire de Limay, 291 Avenue Dreyfous Ducas, Limay 78520 (France); Institut Jean Lamour, departement Chimie et physique des solides et des surfaces, UMR 7198 CNRS - Universite Henri Poincare Nancy 1, Vandoeuvre-Les-Nancy (France); Rapin, C.; Vilasi, M. [Institut Jean Lamour, departement Chimie et physique des solides et des surfaces, UMR 7198 CNRS - Universite Henri Poincare Nancy 1, Vandoeuvre-Les-Nancy (France)

2011-06-15

Combustion of municipal waste generates highly corrosive gases (HCl, SO{sub 2}, NaCl, KCl, and heavy metals chlorides) and ashes containing alkaline chlorides and sulfates. Currently, corrosion phenomena are particularly observed on superheater's tubes. Corrosion rates depend mainly on installation design, operating conditions i.e., gas and steam temperature and velocity of the flue gas containing ashes. This paper presents the results obtained using an innovative laboratory-scale corrosion unit, which simulates MSWI (Municipal Solid Waste Incineration) boilers conditions characterized by a temperature gradient at the metal tube in the presence of corrosive gases and ashes. The presented corrosion tests were realized on carbon steel at fixed metal temperature (400 C). The influence of the flue gas temperature, synthetic ashes composition, and flue gas flow pattern were investigated. After corrosion test, cross sections of tube samples were characterized to evaluate thickness loss and estimate corrosion rate while the elements present in corrosion layers were analyzed. Corrosion tests were carried out twice in order to validate the accuracy and reproducibility of results. First results highlight the key role of molten phase related to the ash composition and flue gas temperature as well as the deposit morphology, related to the flue gas flow pattern, on the mechanisms and corrosion rates. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Cisplatin resistance: a cellular self-defense mechanism resulting from multiple epigenetic and genetic changes.

Science.gov (United States)

Shen, Ding-Wu; Pouliot, Lynn M; Hall, Matthew D; Gottesman, Michael M

2012-07-01

Cisplatin is one of the most effective broad-spectrum anticancer drugs. Its effectiveness seems to be due to the unique properties of cisplatin, which enters cells via multiple pathways and forms multiple different DNA-platinum adducts while initiating a cellular self-defense system by activating or silencing a variety of different genes, resulting in dramatic epigenetic and/or genetic alternations. As a result, the development of cisplatin resistance in human cancer cells in vivo and in vitro by necessity stems from bewilderingly complex genetic and epigenetic changes in gene expression and alterations in protein localization. Extensive published evidence has demonstrated that pleiotropic alterations are frequently detected during development of resistance to this toxic metal compound. Changes occur in almost every mechanism supporting cell survival, including cell growth-promoting pathways, apoptosis, developmental pathways, DNA damage repair, and endocytosis. In general, dozens of genes are affected in cisplatin-resistant cells, including pathways involved in copper metabolism as well as transcription pathways that alter the cytoskeleton, change cell surface presentation of proteins, and regulate epithelial-to-mesenchymal transition. Decreased accumulation is one of the most common features resulting in cisplatin resistance. This seems to be a consequence of numerous epigenetic and genetic changes leading to the loss of cell-surface binding sites and/or transporters for cisplatin, and decreased fluid phase endocytosis.

Optimal results of aortic valve replacement with small mechanical valves (< 19 mm).

Science.gov (United States)

Kato, Yasuyuki; Hattori, Koji; Motoki, Manabu; Takahashi, Yosuke; Kotani, Shinsuke; Nishimura, Shinsuke; Shibata, Toshihiko

2013-07-01

Controversy exists regarding the optimal operative method or type of prosthesis for patients with a small aortic root. The aim of this retrospective study was to investigate the early and mid-term outcomes of standard aortic valve replacement (AVR) using 16 mm or 18 mm ATS Advanced Performance (AP) or 17 mm St. Jude Medical (SJM) Regent valves for a small aortic root. Between April 2003 and August 2009, 78 patients (age range: 50-86 years; 86% aged > or = 65 years) underwent AVR with 16 mm or 18 mm ATS AP valves (16AP group: n = 21, 18AP group: n = 32), or a 17 mm SJM Regent valve (17Regent group: n = 25). Fifty-six patients (72%) had a body surface area (BSA) of regression was similar among the groups (-30%, -25% and -28% in the 16AP, 17Regent and 18AP groups, respectively; p = 0.844). The early and mid-term results of AVR with 16 mm or 18 mm ATS AP valves, or with a 17 mm SJM Regent valve, were satisfactory. Therefore, standard AVR using these small mechanical prostheses, which avoids the need to enlarge the annulus or to conduct stentless bioprosthesis implantation, might represent an acceptable method, especially in elderly patients with a small aortic root.

RC Beams Strengthened with Mechanically Fastened Composites: Experimental Results and Numerical Modeling

Directory of Open Access Journals (Sweden)

Enzo Martinelli

2014-03-01

Full Text Available The use of mechanically-fastened fiber-reinforced polymer (MF-FRP systems has recently emerged as a competitive solution for the flexural strengthening of reinforced concrete (RC beams and slabs. An overview of the experimental research has proven the effectiveness and the potentiality of the MF-FRP technique which is particularly suitable for emergency repairs or when the speed of installation and immediacy of use are imperative. A finite-element (FE model has been recently developed by the authors with the aim to simulate the behavior of RC beams strengthened in bending by MF-FRP laminates; such a model has also been validated by using a wide experimental database collected from the literature. By following the previous study, the FE model and the assembled database are considered herein with the aim of better exploring the influence of some specific aspects on the structural response of MF-FRP strengthened members, such as the bearing stress-slip relationship assumed for the FRP-concrete interface, the stress-strain law considered for reinforcing steel rebars and the cracking process in RC members resulting in the well-known tension stiffening effect. The considerations drawn from this study will be useful to researchers for the calibration of criteria and design rules for strengthening RC beams through MF-FRP laminates.

Low tidal volume and high positive end-expiratory pressure mechanical ventilation results in increased inflammation and ventilator-associated lung injury in normal lungs.

Science.gov (United States)

Hong, Caron M; Xu, Da-Zhong; Lu, Qi; Cheng, Yunhui; Pisarenko, Vadim; Doucet, Danielle; Brown, Margaret; Aisner, Seena; Zhang, Chunxiang; Deitch, Edwin A; Delphin, Ellise

2010-06-01

Protective mechanical ventilation with low tidal volume (Vt) and low plateau pressure reduces mortality and decreases the length of mechanical ventilation in patients with acute respiratory distress syndrome. Mechanical ventilation that will protect normal lungs during major surgical procedures of long duration may improve postoperative outcomes. We performed an animal study comparing 3 ventilation strategies used in the operating room in normal lungs. We compared the effects on pulmonary mechanics, inflammatory mediators, and lung tissue injury. Female pigs were randomized into 3 groups. Group H-Vt/3 (n = 6) was ventilated with a Vt of 15 mL/kg predicted body weight (PBW)/positive end-expiratory pressure (PEEP) of 3 cm H(2)O, group L-Vt/3 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 3 cm H(2)O, and group L-Vt/10 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 10 cm H(2)O, for 8 hours. Hemodynamics, airway mechanics, arterial blood gases, and inflammatory markers were monitored. Bronchoalveolar lavage (BAL) was analyzed for inflammatory markers and protein concentration. The right lower lobe was assayed for mRNA of specific cytokines. The right lower lobe and right upper lobe were evaluated histologically. In contrast to groups H-Vt/3 and L-Vt/3, group L-Vt/10 exhibited a 6-fold increase in inflammatory mediators in BAL (P ventilation with high PEEP resulted in increased production of inflammatory markers. Low PEEP resulted in lower levels of inflammatory markers. High Vt/low PEEP resulted in less histologic lung injury.

Leaching mechanisms

International Nuclear Information System (INIS)

Dougherty, D.R.; Colombo, P.

1984-01-01

Sufficient data are lacking to provide a basis for adequately assessing the long term leaching behavior of solidified low level radioactive waste forms in their disposal environment. Although the release of radioactivity from a waste form to an aqueous environment is recognized to be due to one or more mechanisms such as diffusion, dissolution, corrosion or ion exchange, the leaching mechanisms and the factors which control the leaching behavior of waste forms are not fully understood. This study will determine the prevailing mechanisms for a variety of selected LLW solidification agents which are being considered for use by defense and commercial generators and which will cover the broadest possible number of mechanisms. The investigation will proceed by the postulation of mathematical models representative of the prevailing mechanism(s) and the use of statistically designed experiments to test the actual leaching behavior of laborattory samples against the postulated representations. Maximum use of existing leach data in the literature will be made by incorporating literature results into a computerized data base along with the experimental results generated in this task

Mechanical properties of steel for construction of gas transfer pipelines and their modification resulting from expanding of gas pipelines during hydraulic pressure testing

International Nuclear Information System (INIS)

Kopczynski, A.

1997-01-01

There are discussed the mechanical properties of the new generation of steel as per European Standard EN 10208.2: 1996. on the basis of the mechanical parameters of steel the normalized graphs of steel tensioning are presented. Analysis of influence of expanding gas pipelines on changes of steel tensioning graphs were performed. Advantages, resulting from expanding of gas pipelines, were shown. (author)

Ultraviolet light mutagenesis in bacteria: a result of the failure of normal error-correcting mechanisms

International Nuclear Information System (INIS)

Bridges, B.A.

1980-01-01

The various mechanisms for maintaining the fidelity of DNA base sequences during replication and repair are described. In excision-deficient bacteria an attractive possibility is that UV-induced mutations may arise as a result of the inhibition of the 3' to 5' exonuclease proof reading function of DNA polymerase III, either by means of the induction of a specific inhibitor or by means of feed-back inhibition by nucleoside 5' monophosphates. There is at present no convincing evidence for this model and little evidence that the process has any significant effect on the viability of UV-irradiated bacteria. In bacteria wild-type for repair functions, a model for UV-mutagenesis is proposed which postulates that after low to moderate UV doses, mutations reflect the normal infidelity of DNA polymerases (mainly III) acting during the filling of excision gaps. At higher doses excision gaps may uncover photoproducts on the complementary DNA strand which may result in 'targeted' metagenesis and be revealed as a quadratic component to the dose response curve. (Auth.)

Understanding the mechanisms of lung mechanical stress

Directory of Open Access Journals (Sweden)

C.S.N.B. Garcia

2006-06-01

Full Text Available Physical forces affect both the function and phenotype of cells in the lung. Bronchial, alveolar, and other parenchymal cells, as well as fibroblasts and macrophages, are normally subjected to a variety of passive and active mechanical forces associated with lung inflation and vascular perfusion as a result of the dynamic nature of lung function. These forces include changes in stress (force per unit area or strain (any forced change in length in relation to the initial length and shear stress (the stress component parallel to a given surface. The responses of cells to mechanical forces are the result of the cell's ability to sense and transduce these stimuli into intracellular signaling pathways able to communicate the information to its interior. This review will focus on the modulation of intracellular pathways by lung mechanical forces and the intercellular signaling. A better understanding of the mechanisms by which lung cells transduce physical forces into biochemical and biological signals is of key importance for identifying targets for the treatment and prevention of physical force-related disorders.

Bicipital tenosynovitis in the dog: evaluation with positive contrast arthrography

International Nuclear Information System (INIS)

Barthez, P.Y.; Morgan, J.P.

1993-01-01

This paper describes seven dogs with traumatic bicipital tenosynovitis in which complete clinical, radiographic, and surgical evaluations were performed. All were adult dogs of medium to large breed and were presented with a chronic front limb lameness of several months' duration and shoulder muscle atrophy. Survey radiographs of the scapulohumeral joint showed new bone production almost exclusively in the region of the biceps tendon, i.e., the intertubercular groove and the supraglenoid tuberosity. Arthrograms in six of seven dogs revealed difficulty in filling or irregular filling of the bicipital tendon sheath, best seen on the mediolateral view of the shoulder. On surgical exploration, macroscopic lesions of the tendon and/or the sheath were observed in all dogs and included adhesions, fibrosis, scar tissue, edema, and thickening. Partial tear of the tendon was observed in three dogs

Detoxification mechanisms of honey bees (Apis mellifera) resulting in tolerance of dietary nicotine.

Science.gov (United States)

du Rand, Esther E; Smit, Salome; Beukes, Mervyn; Apostolides, Zeno; Pirk, Christian W W; Nicolson, Susan W

2015-07-02

Insecticides are thought to be among the major factors contributing to current declines in bee populations. However, detoxification mechanisms in healthy, unstressed honey bees are poorly characterised. Alkaloids are naturally encountered in pollen and nectar, and we used nicotine as a model compound to identify the mechanisms involved in detoxification processes in honey bees. Nicotine and neonicotinoids have similar modes of action in insects. Our metabolomic and proteomic analyses show active detoxification of nicotine in bees, associated with increased energetic investment and also antioxidant and heat shock responses. The increased energetic investment is significant in view of the interactions of pesticides with diseases such as Nosema spp which cause energetic stress and possible malnutrition. Understanding how healthy honey bees process dietary toxins under unstressed conditions will help clarify how pesticides, alone or in synergy with other stress factors, lead to declines in bee vitality.

Testing of mechanisms of action of rituximab and clinical results in high-risk patients with aggressive CD20+ lymphoma

International Nuclear Information System (INIS)

Jezersek Novakovic, B.; Juznic Setina, T.; Vovk, M.; Kotnik, V.; Novakovic, S.

2007-01-01

Rituximab has been applied successfully in the treatment of indolent and aggressive CD20 positive B cell lymphomas, yet the exact in vivo mechanisms of its action have not been unambiguously explained. This study was therefore aimed to confirm the presumed major mechanisms of action of rituximab and concomitantly to assess the effectiveness of first-line chemo immunotherapy in high-risk patients with aggressive CD20 lymphomas. The activity of rituximab was tested in vitro on Raji and SU-DHL-4 cells using the cell proliferation assay and flow cytometry. In the clinical part of the study, 20 high-risk patients with aggressive CD 20 lymphomas were treated with R-CHOP. Only complement-mediated cytotoxicity was observed under the in vitro applied experimental conditions. Neither the direct apoptotic effect nor the antibody-dependent cell-mediated cytotoxicity was detected probably due to a too low concentration of rituximab and a too low ratio of cytotoxic lymphocytes to tumor cells. The treatment outcome in patients was excellent since complete remissions were achieved in 90% of poor-risk patients at the end of primary treatment and 80% of patients were disease-free at 18.5 months median observation period. According to our results, the complement-dependent cytotoxicity is an important mechanism of rituximab action in vitro. To achieve direct apoptosis, higher concentrations than 20 μg/ml of rituximab should be used, while for an effective antibody-dependent cell-mediated cytotoxicity, the ratio of cytotoxic lymphocytes to tumor cells should be higher than 1:1. In the high-risk patients with aggressive CD20 lymphomas, the addition of rituximab to CHOP substantially improves the therapeutic results. (author)

Material removal mechanisms in electrochemical-mechanical polishing of tantalum

International Nuclear Information System (INIS)

Gao, F.; Liang, H.

2009-01-01

Material removal mechanisms in tantalum chemical-mechanical polishing (CMP) and electrochemical-mechanical polishing (ECMP) were investigated using the single frequency electrochemical impedance spectroscopy (EIS). Through measuring the impedance of the tantalum surface, the single frequency EIS scan made it possible to observe the CMP and ECMP processes in situ. The impedance results presented competing mechanisms of removal and formation of a surface oxide layer of tantalum. Analysis indicated that the thickness of the oxide layer formed during polishing was related to the mechanical power correlated to the friction force and the rotating speed. Furthermore, the rate of growth and removal of the oxide film was a function of the mechanical power. This understanding is beneficial for optimization of CMP and ECMP processes.

The results of experimental studies of VLF-ULF electromagnetic emission by rock samples due to mechanical action

Science.gov (United States)

Panfilov, A. A.

2014-06-01

The paper presents the results of laboratory experiments on electromagnetic emissions excitation (the electric component of electromagnetic fields) by rock samples due to different forms of mechanical stress applications. It was shown that samples generate electric impulses with different spectra when the impact action, gradual loading or dynamic friction is applied. It was ascertained that level and spectral compositions of signals, generated by rock samples, change with an increasing number of hits. It was found that strong electromagnetic signals, generated while rock samples were fracturing, were accompanied by repetitive weak but perceptible variations in the electric field intensity in short frequency ranges.

Response of the human tympanic membrane to transient acoustic and mechanical stimuli: Preliminary results

Science.gov (United States)

Razavi, Payam; Ravicz, Michael E.; Dobrev, Ivo; Cheng, Jeffrey Tao; Furlong, Cosme; Rosowski, John J.

2016-01-01

The response of the tympanic membrane (TM) to transient environmental sounds and the contributions of different parts of the TM to middle-ear sound transmission were investigated by measuring the TM response to global transients (acoustic clicks) and to local transients (mechanical impulses) applied to the umbo and various locations on the TM. A lightly-fixed human temporal bone was prepared by removing the ear canal, inner ear, and stapes, leaving the incus, malleus, and TM intact. Motion of nearly the entire TM was measured by a digital holography system with a high speed camera at a rate of 42 000 frames per second, giving a temporal resolution of <24 μs for the duration of the TM response. The entire TM responded nearly instantaneously to acoustic transient stimuli, though the peak displacement and decay time constant varied with location. With local mechanical transients, the TM responded first locally at the site of stimulation, and the response spread approximately symmetrically and circumferentially around the umbo and manubrium. Acoustic and mechanical transients provide distinct and complementary stimuli for the study of TM response. Spatial variations in decay and rate of spread of response imply local variations in TM stiffness, mass, and damping. PMID:26880098

Dynamicimagestoaddressconceptualnodes about mechanical waves: Example materials and preliminary results of the experimentation of the teacher training module IMAGONDE

Science.gov (United States)

Testa, I.; Lombardi, S.; Monroy, G.; Sassi, E.

2004-09-01

In the framework of the 2002-03 project “Fisica per la Formazione Culturale - FORMazione Insegnanti" funded by Italy ministry of Education, a set of training materials, focused on mechanical waves, has been developed. The core of the materials is represented by animated images purposely designed in order to: 1) address intrinsically dynamic aspects of one-dimensional impulses/waves propagation on a string; 2) have the trainees reflect upon students' difficulties in reading/interpreting static images (as the ones which are featured in common textbooks) and animations. In this paper we discuss example materials concerning transversal impulses on strings to address conceptual nodes such as: 1) configuration of the string at a given time and its aaabstract representation; 2) displacement vs. time graph of a string element and its aaabstract representation; 3) relationships between the two aaabstract representations; 4) modelization of mechanical wave propagation in one dimension. Moreover the results of the experimentation of the training materials in the framework of the Post Graduate School to Became Physics Teacher in Secondary Schools are presented and commented.

Mechanical properties of copper-lithium alloys produced by mechanic alloyed and hot extrusion

International Nuclear Information System (INIS)

Castillo B, Ricardo; Gorziglia S, Ezio; Penaloza V, Augusto

2004-01-01

In this work are presented the progress carried out on the characterization of some physical and mechanical properties, together with the determination of the micro mechanism of fracture of the Cu-2% wt Li, that was obtained by mechanical alloying followed hot extrusion at 500 o C and 700 o C. Hardness and tensile mechanical tests were performed together with metallographic and fractographic analysis. The experimental results obtained with powders of the Cu-Li alloy studied are compared with powder of pure copper, under similar test conditions. The results show that by hot extrusion was allowed to obtain very high densification levels for the materials under study. Moreover, it was found that lithium reduce both the tensile strength and elongation, of copper by a mechanism of embrittlement. The results are compares with the literature (au)

Calorimetric investigation on mechanically activated storage energy mechanism of sphalerite and pyrite

International Nuclear Information System (INIS)

Xiao Zhongliang; Chen Qiyuan; Yin Zhoulan; Hu Huiping; Wu Daoxin

2005-01-01

The structural changes of mechanically activated sphalerite and pyrite under different grinding conditions were determined by X-ray powder diffraction (XRD), laser particle size analyzer and elemental analysis. The storage energy of mechanically activated sphalerite and pyrite was measured by a calorimetric method. A thermochemical cycle was designed so that mechanically activated and non-activated minerals reached the same final state when dissolved in the same oxidizing solvent. The results show that the storage energy of mechanically activated sphalerite and pyrite rises with increased in grinding time, and reaches a maximum after a certain grinding period. The storage energy of mechanically activated pyrite decreases when heated under inert atmosphere. The storage energy of mechanically activated sphalerite and pyrite remains constant when treated below 573 K under inert atmosphere. The percentage of the storage energy caused by surface area increase during mechanical activation decreases with increasing grinding time. These results support our opinion that the mechanically activated storage energy of sphalerite is closely related to lattice distortions, and the mechanically activated storage energy of pyrite is mainly caused by the formation of reactive sites on the surface

Guidelines to Interpret Results of Mechanical Blade Test

International Nuclear Information System (INIS)

Arias Vega, F.; Sanz Martin, J. C.

1999-01-01

This report shows the interpretation of full scale rotor blade test results and describes the engineering testing models and coefficients for any feasible rotor blade design, in order to accept and to certify any final manufactured blade as an allowable product, fit for use and working with a completely security during all the wind turbines lifetime. This work was carried out at the Wind Energy Division of the CIEMAT.DER and it is based on the authors technical experience in this field, after many years working on testing blades. Also, this paper contains results of the European wind turbine Standards II relevant to the European Project: JOULE III R.D. where the Wind Energy Division took part as participant too. (Author)

Guidelines to Interpret Results of Mechanical Blade Test

Energy Technology Data Exchange (ETDEWEB)

Arias Vega, F.; Sanz Martin, J. C. [Ciemat, Madrid (Spain)

2000-07-01

This report shows the interpretation of full scale rotor blade test results and describes the engineering testing models and coefficients for any feasible rotor blade design, in order to accept and to certify any final manufactured blades as an allowable product, fit for use and working with a completely security during all the windturbine's lifetime. This work was carried out at the Wind Energy Division of the CIEMAT.DER and it is based on the author's technical experience in this field, after many years working on testing blades. Also, this paper contains results of the European wind turbine Standards II relevant to the European Project: JOULE III R.D. where the Wind Energy Division took part as participant too. (Author)

Advances in Applied Mechanics

OpenAIRE

2013-01-01

Advances in Applied Mechanics draws together recent significant advances in various topics in applied mechanics. Published since 1948, Advances in Applied Mechanics aims to provide authoritative review articles on topics in the mechanical sciences, primarily of interest to scientists and engineers working in the various branches of mechanics, but also of interest to the many who use the results of investigations in mechanics in various application areas, such as aerospace, chemical, civil, en...

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion.

Science.gov (United States)

Lui, Jordon; MacGillivray, Megan K; Sheel, A William; Jeyasurya, Jeswin; Sadeghi, Mahsa; Sawatzky, Bonita Jean

2013-01-01

The purpose of this study was to (1) evaluate the mechanical efficiency (ME) of two commercially available lever-propulsion mechanisms for wheelchairs and (2) compare the ME of lever propulsion with hand rim propulsion within the same wheelchair. Of the two mechanisms, one contained a torsion spring while the other used a roller clutch design. We hypothesized that the torsion spring mechanism would increase the ME of propulsion due to a passive recovery stroke enabled by the mechanism. Ten nondisabled male participants with no prior manual wheeling experience performed submaximal exercise tests using both lever-propulsion mechanisms and hand rim propulsion on two different wheelchairs. Cardiopulmonary parameters including oxygen uptake (VO2), heart rate (HR), and energy expenditure (En) were determined. Total external power (Pext) was measured using a drag test protocol. ME was determined by the ratio of Pext to En. Results indicated no significant effect of lever-propulsion mechanism for all physiological measures tested. This suggests that the torsion spring did not result in a physiological benefit compared with the roller clutch mechanism. However, both lever-propulsion mechanisms showed decreased VO2 and HR and increased ME (as a function of slope) compared with hand rim propulsion (p propulsion mechanisms tested are more mechanically efficient than conventional hand rim propulsion, especially when slopes are encountered.

Mechanics of Ballast Compaction. Volume 3 : Field Test Results for Ballast Physical State Measurement

Science.gov (United States)

1982-03-01

The important mechanical processes which influence the ballast physical state in track are tamping, crib and shoulder compaction and train traffic. Three methods of assessing physical state were used at four railroad sites to obtain needed data on th...

Mechanisms of mechanical strain memory in airway smooth muscle.

Science.gov (United States)

Kim, Hak Rim; Hai, Chi-Ming

2005-10-01

We evaluated the hypothesis that mechanical deformation of airway smooth muscle induces structural remodeling of airway smooth muscle cells, thereby modulating mechanical performance in subsequent contractions. This hypothesis implied that past experience of mechanical deformation was retained (or "memorized") as structural changes in airway smooth muscle cells, which modulated the cell's subsequent contractile responses. We termed this phenomenon mechanical strain memory. Preshortening has been found to induce attenuation of both force and isotonic shortening velocity in cholinergic receptor-activated airway smooth muscle. Rapid stretching of cholinergic receptor-activated airway smooth muscle from an initial length to a final length resulted in post-stretch force and myosin light chain phosphorylation that correlated significantly with initial length. Thus post-stretch muscle strips appeared to retain memory of the initial length prior to rapid stretch (mechanical strain memory). Cytoskeletal recruitment of actin- and integrin-binding proteins and Erk 1/2 MAPK appeared to be important mechanisms of mechanical strain memory. Sinusoidal length oscillation led to force attenuation during oscillation and in subsequent contractions in intact airway smooth muscle, and p38 MAPK appeared to be an important mechanism. In contrast, application of local mechanical strain to cultured airway smooth muscle cells induced local actin polymerization and cytoskeletal stiffening. It is conceivable that deep inspiration-induced bronchoprotection may be a manifestation of mechanical strain memory such that mechanical deformation from past breathing cycles modulated the mechanical performance of airway smooth muscle in subsequent cycles in a continuous and dynamic manner.

Coupled thermo-hydro-mechanical experiment at Kamaishi mine. Technical note 15-99-02. Experimental results

Energy Technology Data Exchange (ETDEWEB)

Chijimatsu, Masakazu; Sugita, Yutaka; Fujita, Tomoo [Tokai Works, Waste Management and Fuel Cycle Research Center, Waste Isolation Research Division, Barrier Performance Group, Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan); Amemiya, Kiyoshi [Hazama Corp., Tokyo (Japan)

1999-07-01

It is an important part of the near field performance assessment of nuclear waste disposal to evaluate coupled thermo-hydro-mechanical (T-H-M) phenomena, e.g., thermal effects on groundwater flow through rock matrix and water seepage into the buffer material, the generation of swelling pressure of the buffer material, and thermal stresses potentially affecting porosity and fracture apertures of the rock. An in-situ T-H-M experiment named Engineered Barrier Experiment' has been conducted at the Kamaishi Mine, of which host rock is granodiorite, in order to establish conceptual models of the coupled T-H-M processes and to build confidence in mathematical and computer codes. In 1995, fourteen boreholes were excavated in order to install the various sensors. After the hydraulic tests, mechanical tests were carried out to obtain the rock properties. After that, a test pit, 1.7 m in diameter and 5.0 m in depth, was excavated. During the excavation, the change of pore pressure, displacement and temperature of rock mass were measured. In 1996, the buffer material and heater were set up in the test pit, and then coupled thermo-hydro-mechanical test was started. The duration of heating phase was 250 days and that of cooling phase was 180 days. The heater surface was controlled to be 100degC during heating phase. Measurement was carried out by a number of sensors installed in both buffer and rock mass during the test. The field experiment leads to a better understanding of the behavior of the coupled thermo-hydro-mechanical phenomena in the near field. (author)

The CEASEMT System (Calculation and Analysis of Structures in Mechanics and Thermics). 'ESPACE' 'TEMPS' 'VISU' functions. Automatic processing of the results

International Nuclear Information System (INIS)

Auriol, F.; Jeanpierre, F.; Goldstein, S.; Hoffmann, A.

1976-01-01

The ESPACE code provides the CEASEMT system with two additional capabilities: TRISTANA option is for reading and performing the layout of the tapes issued from the TRISTANA program subroutines; the BANDE option especially oriented towards fluid mechanics allows velocity fields and iso-value charts to be plotted from results stored in a tape [fr

Short-Term Motor Compensations to Denervation of Feline Soleus and Lateral Gastrocnemius Result in Preservation of Ankle Mechanical Output during Locomotion

Science.gov (United States)

Prilutsky, Boris I.; Maas, Huub; Bulgakova, Margarita; Hodson-Tole, Emma F.; Gregor, Robert J.

2011-01-01

Denervation of selected ankle extensors in animals results in locomotor changes. These changes have been suggested to permit preservation of global kinematic characteristics of the hindlimb during stance. The peak ankle joint moment is also preserved immediately after denervation of several ankle extensors in the cat, suggesting that the animal's response to peripheral nerve injury may also be aimed at preserving ankle mechanical output. We tested this hypothesis by comparing joint moments and power patterns during walking before and after denervation of soleus and lateral gastrocnemius muscles. Hindlimb kinematics, ground reaction forces and electromyographic activity of selected muscles were recorded during level, downslope (−50%) and upslope (50%) walking before and 1–3 weeks after nerve denervation. Denervation resulted in increased activity of the intact medial gastrocnemius and plantaris muscles, greater ankle dorsiflexion, smaller knee flexion, and the preservation of the peak ankle moment during stance. Surprisingly, ankle positive power generated in the propulsion phase of stance was increased (up to 50%) after denervation in all walking conditions (p ankle. The additional mechanical energy generated at the ankle during propulsion can result, in part, from increased activity of intact synergists, the use of passive tissues around the ankle and by the tendon action of ankle two-joint muscles and crural fascia. PMID:21411965

Results of monitoring at Olkiluoto in 2009. Rock mechanics

International Nuclear Information System (INIS)

Lahti, M.; Hakala, M.

2010-09-01

The rock mechanical monitoring at Olkiluoto concentrates on the assessment of potential tectonic movements and stability of the bedrock. The construction of ONKALO is not expected to induce large-scale movements of the rock blocks or affect the rate of isostatic uplift but the evaluation of any tectonic events is important for the safety assessment. The monitoring consists of seismic measurements, GPS measurements and precise levelling campaigns at Olkiluoto and vicinity and additionally extensometer and convergence measurements carried out in ONKALO. Posiva established a local seismic network of six stations on the island of Olkiluoto in 2002. The number of seismic stations has increased gradually being in 2009 altogether 14. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The investigation area includes two target areas. The larger target area, called seismic semi-regional area, covers the Olkiluoto Island and its surroundings. The purpose is to monitor explosions and tectonic earthquakes in regional scale. The smaller target area is s called the seismic ONKALO block, which is a 2 km *2 km *2 km cube surrounding the ONKALO. All the expected excavation induced events assumingly occur within this volume. At the moment the seismic ONKALO block includes 10 seismic stations. An additional task of monitoring is related to safeguarding of the ONKALO. The seismic network has operated continuously in 2009 and during the year altogether 1256 events have been located in the Olkiluoto area. Most of them (1161) are explosions that occurred inside the seismic semi-regional area and especially inside the seismic ONKALO block (1135 events)

Survey report on smart-tribo-mechanics; Smart tribo mechanics

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Survey results of smart-tribo-mechanics are described. For the smart-tribo-mechanics differing from the conventional tribology, an intelligent system is constructed by making full use of various science and technology ranging from basic to application, to solve problems. Self-diagnosis and self-remediation, active control, passive control, and smart-biotribo-mechanics are typical methods. Electronics, telecommunication, healthcare, and new biotechnology are new and advanced application areas. In these areas, tribology to control and act to the material surface in the atomic and molecular scale should be the key technology. In addition, the smart-tribo-mechanics is expected to be used for sustaining basic industry, such as material, transportation, and life industries. 101 refs., 67 figs., 14 tabs.

A quantum mechanics/molecular mechanics study on the hydrolysis mechanism of New Delhi metallo-β-lactamase-1.

Science.gov (United States)

Zhu, Kongkai; Lu, Junyan; Liang, Zhongjie; Kong, Xiangqian; Ye, Fei; Jin, Lu; Geng, Heji; Chen, Yong; Zheng, Mingyue; Jiang, Hualiang; Li, Jun-Qian; Luo, Cheng

2013-03-01

New Delhi metallo-β-lactamase-1 (NDM-1) has emerged as a major global threat to human health for its rapid rate of dissemination and ability to make pathogenic microbes resistant to almost all known β-lactam antibiotics. In addition, effective NDM-1 inhibitors have not been identified to date. In spite of the plethora of structural and kinetic data available, the accurate molecular characteristics of and details on the enzymatic reaction of NDM-1 hydrolyzing β-lactam antibiotics remain incompletely understood. In this study, a combined computational approach including molecular docking, molecular dynamics simulations and quantum mechanics/molecular mechanics calculations was performed to characterize the catalytic mechanism of meropenem catalyzed by NDM-1. The quantum mechanics/molecular mechanics results indicate that the ionized D124 is beneficial to the cleavage of the C-N bond within the β-lactam ring. Meanwhile, it is energetically favorable to form an intermediate if no water molecule coordinates to Zn2. Moreover, according to the molecular dynamics results, the conserved residue K211 plays a pivotal role in substrate binding and catalysis, which is quite consistent with previous mutagenesis data. Our study provides detailed insights into the catalytic mechanism of NDM-1 hydrolyzing meropenem β-lactam antibiotics and offers clues for the discovery of new antibiotics against NDM-1 positive strains in clinical studies.

Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. Result report

International Nuclear Information System (INIS)

Chijimatsu, Masakazu; Amemiya, Kiyoshi; Shiozaki, Isao; Neyama, Atsushi; Iwata, Hiroshi; Nakagawa, Koichi; Ishihara, Yoshinao; Sagawa, Hiroshi

2002-02-01

In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe 60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysis code (HYDROGEOCHEM). (6) We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling

Pharmaceutical counselling about different types of tablet-splitting methods based on the results of weighing tests and mechanical development of splitting devices.

Science.gov (United States)

Somogyi, O; Meskó, A; Csorba, L; Szabó, P; Zelkó, R

2017-08-30

The division of tablets and adequate methods of splitting them are a complex problem in all sectors of health care. Although tablet-splitting is often required, this procedure can be difficult for patients. Four tablets were investigated with different external features (shape, score-line, film-coat and size). The influencing effect of these features and the splitting methods was investigated according to the precision and "weight loss" of splitting techniques. All four types of tablets were halved by four methods: by hand, with a kitchen knife, with an original manufactured splitting device and with a modified tablet splitter based on a self-developed mechanical model. The mechanical parameters (harness and friability) of the products were measured during the study. The "weight loss" and precision of splitting methods were determined and compared by statistical analysis. On the basis of the results, the external features (geometry), the mechanical parameters of tablets and the mechanical structure of splitting devices can influence the "weight loss" and precision of tablet-splitting. Accordingly, a new decision-making scheme was developed for the selection of splitting methods. In addition, the skills of patients and the specialties of therapy should be considered so that pharmaceutical counselling can be more effective regarding tablet-splitting. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of R6 and A16 J estimation methods under combined mechanical and thermal loads with FE results

International Nuclear Information System (INIS)

Nam, Hyun-Suk; Oh, Chang-Young; Kim, Yun-Jae; Jerng, Dong Wook; Ainsworth, Robert A.; Budden, Peter J.; Marie, Stéphane

2015-01-01

This paper compares elastic–plastic values of J calculated using the methods in the UK R6 and the French A16 fitness-for-service procedures with FE results for a vessel with a circumferential surface crack under axial tension and a radial thermal gradient. In the FE analyses, the relative magnitudes and loading sequence of mechanical and thermal loads are systematically varied, together with the material strain hardening exponent. Fully circumferential and semi-elliptical surface crack with two relative crack depths are considered. It is found that the R6 estimates are overall accurate but can be non-conservative at large L_r. The A16 estimates are more conservative than the R6 estimates at small L_r but are conservative even at large L_r. Possible sources of conservatism and non-conservatism in R6 and A16 are discussed. - Highlights: • Accuracy of existing J estimation methods for combined mechanical and thermal loading are compared with FE results. • The methods in the UK R6 and the French A16 procedures are considered. • The R6 estimates are overall accurate but can be non-conservative at large L_r. • The A16 estimates are more conservative than the R6 estimates at small L_r but are conservative even at large L_r. • Possible sources of conservatism and non-conservatism in R6 and A16 are discussed.

Reinforcing mechanism of anchors in slopes: a numerical comparison of results of LEM and FEM

Science.gov (United States)

Cai, Fei; Ugai, Keizo

2003-06-01

This paper reports the limitation of the conventional Bishop's simplified method to calculate the safety factor of slopes stabilized with anchors, and proposes a new approach to considering the reinforcing effect of anchors on the safety factor. The reinforcing effect of anchors can be explained using an additional shearing resistance on the slip surface. A three-dimensional shear strength reduction finite element method (SSRFEM), where soil-anchor interactions were simulated by three-dimensional zero-thickness elasto-plastic interface elements, was used to calculate the safety factor of slopes stabilized with anchors to verify the reinforcing mechanism of anchors. The results of SSRFEM were compared with those of the conventional and proposed approaches for Bishop's simplified method for various orientations, positions, and spacings of anchors, and shear strengths of soil-grouted body interfaces. For the safety factor, the proposed approach compared better with SSRFEM than the conventional approach. The additional shearing resistance can explain the influence of the orientation, position, and spacing of anchors, and the shear strength of soil-grouted body interfaces on the safety factor of slopes stabilized with anchors.

Experimental results of single screw mechanical tests: a follow-up to SAND2005-6036.

Energy Technology Data Exchange (ETDEWEB)

Lee, Sandwook; Lee, Kenneth L.; Korellis, John S.; McFadden, Sam X.

2006-08-01

The work reported here was conducted to address issues raised regarding mechanical testing of attachment screws described in SAND2005-6036, as well as to increase the understanding of screw behavior through additional testing. Efforts were made to evaluate fixture modifications and address issues of interest, including: fabrication of 45{sup o} test fixtures, measurement of the frictional load from the angled fixture guide, employment of electromechanical displacement transducers, development of a single-shear test, and study the affect of thread start orientation on single-shear behavior. A286 and 302HQ, No.10-32 socket-head cap screws were tested having orientations with respect to the primary loading axis of 0{sup 0}, 45{sup o}, 60{sup o}, 75{sup o} and 90{sup o} at stroke speeds 0,001 and 10 in/sec. The frictional load resulting from the angled screw fixture guide was insignificant. Load-displacement curves of A286 screws did not show a minimum value in displacement to failure (DTF) for 60{sup o} shear tests. Tests of 302HQ screws did not produce a consistent trend in DTF with load angle. The effect of displacement rate on DTF became larger as shear angle increased for both A286 and 302HQ screws.

Genomic interrogation of mechanism(s) underlying cellular responses to toxicants

International Nuclear Information System (INIS)

Amin, Rupesh P.; Hamadeh, Hisham K.; Bushel, Pierre R.; Bennett, Lee; Afshari, Cynthia A.; Paules, Richard S.

2002-01-01

Assessment of the impact of xenobiotic exposure on human health and disease progression is complex. Knowledge of mode(s) of action, including mechanism(s) contributing to toxicity and disease progression, is valuable for evaluating compounds. Toxicogenomics, the subdiscipline which merges genomics with toxicology, holds the promise to contributing significantly toward the goal of elucidating mechanism(s) by studying genome-wide effects of xenobiotics. Global gene expression profiling, revolutionized by microarray technology and a crucial aspect of a toxicogenomic study, allows measuring transcriptional modulation of thousands of genes following exposure to a xenobiotic. We use our results from previous studies on compounds representing two different classes of xenobiotics (barbiturate and peroxisome proliferator) to discuss the application of computational approaches for analyzing microarray data to elucidate mechanism(s) underlying cellular responses to toxicants. In particular, our laboratory demonstrated that chemical-specific patterns of gene expression can be revealed using cDNA microarrays. Transcript profiling provides discrimination between classes of toxicants, as well as, genome-wide insight into mechanism(s) of toxicity and disease progression. Ultimately, the expectation is that novel approaches for predicting xenobiotic toxicity in humans will emerge from such information

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact.

Science.gov (United States)

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-12

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from 'electrochemical' to 'mechanical', which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

The mechanicism as a result of the development of the mechanics of the XVIIth century

Directory of Open Access Journals (Sweden)

Яна Петрівна Карлікова

2015-11-01

Full Text Available The analysis of the characteristic features of the society historical development in the XVIIth century, scientific discoveries in mechanics has been done. It was due to the needs of production, the formation of capitalist social relations that these discoveries were made. The contribution of Rene Descartes and Isaac Newton in the formation of classical mechanics was investigated. It was shown that the establishing of scientific knowledge occurred in bitter struggle against scholasticism, the old approaches to seeing the world, breaking of Aristotle’s provisions, that had been sharply criticized by a new generation of scientists. It was proved that mechanicism (a new philosophical approach didn’t appear by chance and it was a reflection of the turbulent, complex processes that took place in mechanics, the laws of which had been considered universal and applied to characterize not just natural sciences but social trends as well. Philosophical views of mechanicism founders, R. Descartes and I. Newton were analyzed. Peculiar approaches of these scholars to the scientific picture of the world, what they have in common and what is different in their approaches have been analyzed. Descartes and Newton’s methodology of understanding the world was highlighted as well (deductive and inductive methods of investigation respectively. It was established that it was impossible to step away from the mechanistic principle, because there were no other thoroughly developed scientific systems and laws. Such philosophical conclusions as avoiding definitions, that could be wrong; the desire to reduce the complicated to the most simple elements, the belief that the true accurancy of thinking exists in the mind I (ego cogito were highlighted. Descartes’s vortex theory as the basis of the Universe creation, recognition and acception of only mechanical form of motion of matter were also highlighted. Peculiar features of philosophical approaches of Newton, who

The results of investigation and the analysis of the mechanical properties of L485MB steel used for gas-pipelines construction

International Nuclear Information System (INIS)

Wasiak, J.; Szteke, W.; Bilous, W.; Hajewska, E.; Wagner, T.; Przyborska, M.

2001-01-01

In the paper results of mechanical properties investigation carried out on two sectors of the tube made of L485MB steel cutting out from the gas pipeline after stress test are described. The calculation of the critical dimensions of cracks in examined material is given. The diagnostic programme SACC serving to the evaluation of the exploitation safety of elements with cracks was applied. (author)

Statistical mechanics of fluids under internal constraints: Rigorous results for the one-dimensional hard rod fluid

International Nuclear Information System (INIS)

Corti, D.S.; Debenedetti, P.G.

1998-01-01

The rigorous statistical mechanics of metastability requires the imposition of internal constraints that prevent access to regions of phase space corresponding to inhomogeneous states. We derive exactly the Helmholtz energy and equation of state of the one-dimensional hard rod fluid under the influence of an internal constraint that places an upper bound on the distance between nearest-neighbor rods. This type of constraint is relevant to the suppression of boiling in a superheated liquid. We determine the effects of this constraint upon the thermophysical properties and internal structure of the hard rod fluid. By adding an infinitely weak and infinitely long-ranged attractive potential to the hard core, the fluid exhibits a first-order vapor-liquid transition. We determine exactly the equation of state of the one-dimensional superheated liquid and show that it exhibits metastable phase equilibrium. We also derive statistical mechanical relations for the equation of state of a fluid under the action of arbitrary constraints, and show the connection between the statistical mechanics of constrained and unconstrained ensembles. copyright 1998 The American Physical Society

Design of mechanical joints

CERN Document Server

Blake, Alexander

2018-01-01

A cornerstone publication that covers the basic principles and practical considerations of design methodology for joints held by rivets, bolts, weld seams, and adhesive materials, Design of Mechanical Joints gives engineers the practical results and formulas they need for the preliminary design of mechanical joints, combining the essential topics of joint mechanics...strength of materials...and fracture control to provide a complete treatment of problems pertinent to the field of mechanical connections.

Introductory Education for Mechanical Engineering by Exercise in Mechanical Disassembly

Science.gov (United States)

Matsui, Yoshio; Asakawa, Naoki; Iwamori, Satoru

An introductory program “Exercise for engineers in mechanical disassembly” is an exercise that ten students of every team disassemble a motor scooter to the components and then assemble again to the initial form in 15 weeks. The purpose of this program is to introduce mechanical engineering by touching the real machine and learning how it is composed from various mechanical parts to the students at the early period after the entrance into the university. Additional short lectures by young teachers and a special lecture by a top engineer in the industry encourage the students to combine the actual machine and the mechanical engineering subjects. Furthermore, various educations such as group leader system, hazard prediction training, parts filing are included in this program. As a result, students recognize the importance of the mechanical engineering study and the way of group working.

Evaluation of carbohydrate molecular mechanical force fields by quantum mechanical calculations

DEFF Research Database (Denmark)

Hemmingsen, Lars Bo Stegeager; Madsen, D.E.; Esbensen, A.L.

2004-01-01

of the (gg, gt and tg) rotamers of methyl alpha-D-glucopyranoside and methyl alpha-D-galactopyranoside are (0.13, 0.00, 0.15) and (0.64, 0.00, 0.77) kcal/mol. respectively. The results of the quantum mechanical calculations are compared with the results of calculations using the 20 second...... for monosaccharide carbohydrate benchmark systems. Selected results are: (i) The interaction energy of the alpha-D-alucopyranose-H2O heterodimer is estimated to be 4.9 kcal/mol, using a composite method including terms at highly correlated (CCSD(T)) level. Most molecular mechanics force fields are in error...

Bipolar radiofrequency in the treatment of dermatologic imperfections: clinicopathological and immunohistochemical aspects.

Science.gov (United States)

Montesi, Gianni; Calvieri, Stefano; Balzani, Alberto; Gold, Michael H

2007-09-01

Rapid progress in the technology for skin rejuvenation has allowed for shorter post-treatment times than ever before. An example of such technology is the radiofrequency (RF) device, which offers nonablative skin rejuvenation, particularly for skin tightening and wrinkle reduction. Medical devices that emit RF energy produce a change in the electrical charges of the treated skin creating an electron movement, and the resistance of the tissue to the electron movement generates heat. This article examines the mechanism of action of a new bipolar RF device, which emits RF energy through a handpiece with a bipolar electrode configuration, and assesses the clinical histological and immunohistochemical results on a sample group of patients who underwent a cycle of sessions with this device. Thirty patients affected with periocular wrinkles, glabellar wrinkles, slackness of the cheeks with accentuation of the nasogenian furrow, striae distensae at the scapulohumeral joint, abdomen, and gluteal-trochanteric areas, or acne scars were included. These patients underwent a cycle of 6 to 8 sessions with 2-week intervals with the new bipolar RF device undergoing photographic monitoring before treatment and at the end of the cycle of sessions. In addition, 15 patients from the sample group were subjected to 2 biopsies, one at the start of treatment and the other 3 months after the last treatment. All the patients showed improvement in treated imperfections from the second session onward, and they expressed their satisfaction at the end of the treatment cycle. The most notable clinical, histological, and immunohistochemical results were observed in the patients with abdominal striae distensae. In most cases, the temporary side effects observed consisted of rashes and ecchymosis. Two patients reported the formation of blisters on the treated area caused by excessively high RF settings. The new bipolar RF device proved to be effective, noninvasive, and easy to use. The improvement

ITER baffle module small-scale mock-ups: first wall thermo-mechanical testing results

International Nuclear Information System (INIS)

Severi, Y.; Giancarli, L.; Poitevin, Y.; Salavy, J.F.; Le Marois, G.; Roedig, M.; Vieider, G.

1998-01-01

The EU-home team is in charge of the R and D related to the ITER baffle first wall. Five small-scale mock-ups, using Be, CFC and W tiles and different armour/heat-sink material joints under development, have been fabricated and thermomechanically tested in FE200 (Le Creusot) and JUDITH (Juelich) electron beam facilities. The small-scale mock-ups have been submitted to thermo-mechanical fatigue tests (up to failure using accelerating techniques). The objective was to determine the performances of the armour material joints under high heat flux cycles. (orig.)

Wheat grain mechanical vulnerability to mechanical damage in light of the recent agrophysical research

International Nuclear Information System (INIS)

Grundas, S.

1995-01-01

The paper contains basic information on mechanical damage to wheat grains. The most important causes of mechanical damage and some of its effects in manufacturing are discussed. Grain material included 5 varieties of winter wheat and 2 varieties of spring wheat. Internal mechanical damage was examined by X-ray technique; external damage was examined with the colorimeter method. The results obtained were compared with the estimation results of more important processing features of the grain: gluten quantity and quality and grain hardness. (author)

CGILS : Results from the first phase of an international project to understand the physical mechanisms of low cloud feedbacks in single column models

NARCIS (Netherlands)

Zhang, M.; Bretherton, C.S.; Blossey, P.N.; Austin, P.H.; Bacmeister, J.T.; Bony, S.; Brient, F.; Cheedela, S.K.; Cheng, A.; Del Genio, A.D.; De Roode, S.R.; Endo, S.; Franklin, C.N.; Golaz, J.C.; Hannay, C.; Heus, T.; Isotta, F.A.; Dufresne, J.L.; Kang, I.S.; Kawai, H.; Köhler, M.; Larson, V.E.; Liu, Y.; Lock, A.P.; Lohmann, U.; Khairoutdinov, M.F.; Molod, A.M.; Neggers, R.A.J.; Rasch, P.; Sandu, I.; Senkbeil, R.; Siebesma, A.P.; Siegenthaler-Le Drian, C.; Stevens, B.; Suarez, M.J.; Xu, K.M.; Von Salzen, K.; Webb, M.J.; Wolf, A.; Zhao, M.

2013-01-01

CGILS—the CFMIP-GASS Intercomparison of Large Eddy Models (LESs) and single column models (SCMs)—investigates the mechanisms of cloud feedback in SCMs and LESs under idealized climate change perturbation. This paper describes the CGILS results from 15 SCMs and 8 LES models. Three cloud regimes over

Preliminary results of very fast computation of Moment Magnitude and focal mechanism in the context of tsunami warning

Science.gov (United States)

Schindelé, François; Roch, Julien; Rivera, Luis

2015-04-01

Various methodologies were recently developed to compute the moment magnitude and the focal mechanism, thanks to the real time access to numerous broad-band seismic data. Several methods were implemented at the CENALT, in particular the W-Phase method developed by H. Kanamori and L. Rivera. For earthquakes of magnitudes in the range 6.5-9.0, this method provides accurate results in less than 40 minutes. The context of the tsunami warning in Mediterranean, a small basin impacted in less than one hour, and with small sources but some with high tsunami potential (Boumerdes 2003), a comprehensive tsunami warning system in that region should include very fast computation of the seismic parameters. The results of the values of Mw, the focal depth and the type of fault (reverse, normal, strike-slip) are the most relevant parameters expected for the tsunami warning. Preliminary results will be presented using data in the North-eastern and Mediterranean region for the recent period 2010-2014. This work is funded by project ASTARTE - - Assessment, Strategy And Risk Reduction for Tsunamis in Europe - FP7-ENV2013 6.4-3, Grant 603839

Wave Mechanics or Wave Statistical Mechanics

International Nuclear Information System (INIS)

Qian Shangwu; Xu Laizi

2007-01-01

By comparison between equations of motion of geometrical optics and that of classical statistical mechanics, this paper finds that there should be an analogy between geometrical optics and classical statistical mechanics instead of geometrical mechanics and classical mechanics. Furthermore, by comparison between the classical limit of quantum mechanics and classical statistical mechanics, it finds that classical limit of quantum mechanics is classical statistical mechanics not classical mechanics, hence it demonstrates that quantum mechanics is a natural generalization of classical statistical mechanics instead of classical mechanics. Thence quantum mechanics in its true appearance is a wave statistical mechanics instead of a wave mechanics.

Bacterial Cell Mechanics.

Science.gov (United States)

Auer, George K; Weibel, Douglas B

2017-07-25

Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.

Molecular mechanisms in compatibility and mechanical properties of Polyacrylamide/Polyvinyl alcohol blends.

Science.gov (United States)

Wei, Qinghua; Wang, Yanen; Che, Yu; Yang, Mingming; Li, Xinpei; Zhang, Yingfeng

2017-01-01

The objectives of this study were to develop a computational model based on molecular dynamics technique to investigate the compatibility and mechanical properties of Polyacrylamide (PAM)/Polyvinyl alcohol (PVA) blends. Five simulation models of PAM/PVA with different composition ratios (4/0, 3/1, 2/2, 1/3, 0/4) were constructed and simulated by using molecular dynamics (MD) simulation. The interaction mechanisms of molecular chains in PAM/PVA blend system were elaborated from the aspects of the compatibility, mechanical properties, binding energy and pair correlation function, respectively. The computed values of solubility parameters for PAM and PVA indicate PAM has a good miscibility with PVA. The results of the static mechanical analysis, based on the equilibrium structures of blends with differing component ratios, shows us that the elastic coefficient, engineering modulus, and ductility are increased with the addition of PVA content, which is 4/0 PAM/PVAPVAPVAPVAPVA. Moreover, binding energy results indicate that a stronger interaction exists among PVA molecular chains comparing with PAM molecular chains, which is why the mechanical properties of blend system increasing with the addition of PVA content. Finally, the results of pair correlation functions (PCFs) between polar functional groups and its surrounding hydrogen atoms, indicated they interact with each other mainly by hydrogen bonds, and the strength of three types of polar functional groups has the order of O(-OH)>O(-C=O)>N(-NH 2 ). This further elaborates the root reason why the mechanical properties of blend system increase with the addition of PVA content. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanical Characterization of Bone: State of the Art in Experimental Approaches-What Types of Experiments Do People Do and How Does One Interpret the Results?

Science.gov (United States)

Bailey, Stacyann; Vashishth, Deepak

2018-06-18

The mechanical integrity of bone is determined by the direct measurement of bone mechanical properties. This article presents an overview of the current, most common, and new and upcoming experimental approaches for the mechanical characterization of bone. The key outcome variables of mechanical testing, as well as interpretations of the results in the context of bone structure and biology are also discussed. Quasi-static tests are the most commonly used for determining the resistance to structural failure by a single load at the organ (whole bone) level. The resistance to crack initiation or growth by fracture toughness testing and fatigue loading offers additional and more direct characterization of tissue material properties. Non-traditional indentation techniques and in situ testing are being increasingly used to probe the material properties of bone ultrastructure. Destructive ex vivo testing or clinical surrogate measures are considered to be the gold standard for estimating fracture risk. The type of mechanical test used for a particular investigation depends on the length scale of interest, where the outcome variables are influenced by the interrelationship between bone structure and composition. Advancement in the sensitivity of mechanical characterization techniques to detect changes in bone at the levels subjected to modifications by aging, disease, and/or pharmaceutical treatment is required. As such, a number of techniques are now available to aid our understanding of the factors that contribute to fracture risk.

Interatom results for stage 2

International Nuclear Information System (INIS)

Coors, D.

1990-01-01

This report contains the Interatom results for Stage 2 of the ''IWGFR Programme on Intercomparison of LMFBR Core Mechanics Codes'' which was agreed upon on a Consultants Meeting in Vienna, 8-10 December, 1987. The calculations were performed with the 3D core mechanics code system DDT developed at Interatom and with the 2D core mechanics code FIAT. (author). 5 refs, 11 figs, 8 tabs

Parametric study of control mechanism of cortical bone remodeling under mechanical stimulus

Science.gov (United States)

Wang, Yanan; Qin, Qing-Hua

2010-03-01

The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.

Respiratory mechanics to understand ARDS and guide mechanical ventilation.

Science.gov (United States)

Mauri, Tommaso; Lazzeri, Marta; Bellani, Giacomo; Zanella, Alberto; Grasselli, Giacomo

2017-11-30

As precision medicine is becoming a standard of care in selecting tailored rather than average treatments, physiological measurements might represent the first step in applying personalized therapy in the intensive care unit (ICU). A systematic assessment of respiratory mechanics in patients with the acute respiratory distress syndrome (ARDS) could represent a step in this direction, for two main reasons. Approach and Main results: On the one hand, respiratory mechanics are a powerful physiological method to understand the severity of this syndrome in each single patient. Decreased respiratory system compliance, for example, is associated with low end expiratory lung volume and more severe lung injury. On the other hand, respiratory mechanics might guide protective mechanical ventilation settings. Improved gravitationally dependent regional lung compliance could support the selection of positive end-expiratory pressure and maximize alveolar recruitment. Moreover, the association between driving airway pressure and mortality in ARDS patients potentially underlines the importance of sizing tidal volume on respiratory system compliance rather than on predicted body weight. The present review article aims to describe the main alterations of respiratory mechanics in ARDS as a potent bedside tool to understand severity and guide mechanical ventilation settings, thus representing a readily available clinical resource for ICU physicians.

HYDRAULIC SERVO CONTROL MECHANISM

Science.gov (United States)

Hussey, R.B.; Gottsche, M.J. Jr.

1963-09-17

A hydraulic servo control mechanism of compact construction and low fluid requirements is described. The mechanism consists of a main hydraulic piston, comprising the drive output, which is connected mechanically for feedback purposes to a servo control piston. A control sleeve having control slots for the system encloses the servo piston, which acts to cover or uncover the slots as a means of controlling the operation of the system. This operation permits only a small amount of fluid to regulate the operation of the mechanism, which, as a result, is compact and relatively light. This mechanism is particuiarly adaptable to the drive and control of control rods in nuclear reactors. (auth)

FY 2000 report on the results of the R and D of the fusion domain. Volume 3. Biomolecular mechanism and design; 2000 nendo yugo ryoiki kenkyu kaihatsu. 3. Biomolecular mechanism and design

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

For the purpose of creating cells/tissue assemblies and the molecular machine that substitute for self-organizing and self-repairing functions of a living body outside the body, the basic technology research was conducted, and the FY 2000 results were reported. In the study of 3D cell and tissue module engineering, the following were conducted: study of the surface modification and functional expression of biomaterials, study of the mechanical stress to cartilaginous cells and the response, development of the production method of biodegradable synthetic polymer porous materials, study of organism hard tissue materials/bone remodeling and cultured bone transportation, development of zinc-releasing calcium phosphate ceramics. In the study of biomolecular mechanism and design, 1D unidirectional movement of microtubules by applying microlithography technology, structural study of kinesin-family molecular motor by low temperature microscope, ribozyme and the application to leukemia, basic study on assessment of chemical substances by human cultured cells, study of a low molecule detection system using nucleic acid and peptide. (NEDO)

A coupled mechanical-hydrological investigation of crystalline rocks: Annual technical progress report, proposed test matrix, and preliminary results

International Nuclear Information System (INIS)

Bastian, R.J.; Voss, C.F.; Apted, M.J.; Shotwell, L.R.

1988-02-01

This report reviews the Fracture Flow Behavior in Rock Study being performed at the Pacific Northwest Laboratory. The study's objective is to determine the feasibility of predicting mechanical-hydrological behavior of natural rock fractures by accurately characterizing fracture surface topography and mineralization. A laboratory-scale facility is currently being used to ensure optimum control of variables. Devising a technique to study small-scale samples is the first step to understanding the complex coupled processes encountered in geomechanics and hydrology. The major accomplishments during fiscal year 1987 were initial development of the innovative testing method, identification of appropriate specimens, substantial renovation to the facility, completion of several sets of experiments, and procurement of hardware components for a laser-imaging device used to characterize fracture surfaces. A complete set of preliminary results and findings is presented in this report. These results, gathered from a basalt core with a natural fracture, have demonstrated that the methodology is valid, and definite trends in the data are readily apparent. 10 refs., 14 figs., 1 tab

A constitutive model for the thermo-mechanical behaviour of fusion-relevant pebble beds and its application to the simulation of HELICA mock-up experimental results

International Nuclear Information System (INIS)

Vella, G.; Maio, P.A. Di; Giammusso, R.; Tincani, A.; Orco, G. Dell

2006-01-01

Within the framework of the activities promoted by European Fusion Development Agreement on the technology of the Helium Cooled Pebble Bed Test Blanket Module to be irradiated in one of the ITER equatorial ports, attention has been focused on the theoretical modelling of the thermo-mechanical constitutive behaviour of both beryllium and lithiated ceramics pebble beds, that are envisaged to act respectively as neutron multiplier and tritium breeder. The thermo-mechanical behaviour of the pebble beds and their nuclear performances in terms of tritium production depend on the reactor relevant conditions (heat flux and neutron wall load), the pebble sizes and the breeder cell geometries (bed thickness, pebble packing factor, bed overall thermal conductivity). ENEA-Brasimone and the Department of Nuclear Engineering (DIN) of the Palermo University have performed intense research activities intended to investigate fusion-relevant pebble bed thermo-mechanical behaviour by adopting both experimental and theoretical approaches. In particular, ENEA has carried out several experimental campaigns on small scale mock-ups tested in out-of-pile conditions, while DIN has developed a proper constitutive model that has been implemented on commercial FEM code, for the prediction of the thermal and mechanical performances of fusion-relevant pebble beds and for the comparison with the experimental results of the ENEA tests. In that framework, HELICA mock-up has been set-up and tested to investigate the behaviour of pebble bed in reactor-relevant geometries, providing useful data sets to be numerically reproduced by means of the DIN constitutive model, contributing to its assessment. The paper presents the constitutive model developed and the main experimental results of two test campaigns on HELICA mock-up carried out at HE-FUS 3 facility of ENEA Brasimone, the geometry of the mock-up, the adopted thermal and mechanical boundary conditions and the test operating conditions. The most

Mechanisms of gas retention and release: Experimental results for Hanford single-shell waste tanks 241-A-101, 241-S-106, and 241-U-103

International Nuclear Information System (INIS)

Rassat, S.D.; Caley, S.M.; Bredt, P.R.; Gauglitz, P.A.; Rinehart, D.E.; Forbes, S.V.

1998-09-01

The 177 underground waste storage tanks at the Hanford Site contain millions of gallons of radioactive waste resulting from the purification of nuclear materials and related processes. Through various mechanisms, flammable gas mixtures of hydrogen, ammonia, methane, and nitrous oxide are generated and retained in significant quantities within the waste in many (∼25) of these tanks. The potential for large releases of retained gas from these wastes creates a flammability hazard. It is a critical component of the effort to understand the flammability hazard and a primary goal of this laboratory investigation to establish an understanding of the mechanisms of gas retention and release in these wastes. The results of bubble retention experimental studies using waste samples from several waste tanks and a variety of waste types support resolution of the Flammable Gas Safety Issue. Gas bubble retention information gained in the pursuit of safe storage will, in turn, benefit future waste operations including salt-well pumping, waste transfers, and sluicing/retrieval

Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena. 2. Result report

International Nuclear Information System (INIS)

Ishihara, Yoshinao; Ito Takaya; Chijimatsu, Masakazu; Amemiya, Kiyoshi; Shiozaki, Isao; Neyama, Atsushi; Tanaka, Yumiko

2003-02-01

In order to realize a coupling analysis in the near field of the geological disposal system, the coupling analysis code on the thermo-hydro-mechanical-chemical phenomena by THAMES, Dtransu and phreeqe60, which are existing analysis code, is developed in this study. And we carried out the case analysis on the thermo-hydro-mechanical-chemical phenomena by this code. (1) We have developed coupling analysis system to manage coupling analysis and to control coupling process automatically for THAMES (thermo-hydro-mechanical analysis code), Dtransu (mass transport analysis code) and phreeqe60 (geochemical analysis code). (2) Some supporting module, which includes transfer of dissolution concentration and total concentration (dissolution + precipitation concentration), was prepared as a functional expansion. And in order to treat multi-chemical elements, we have codified mass transport analysis code. (3) We have prepared hydraulic conductivity module of buffer material depending on change of dry density due to chemical equilibrium (dissolution and precipitation of minerals), and change of concentration of NaCl solutions. After THAMES, Dtransu, phreeqe60 and hydraulic conductivity module were installed in the COUPLYS, sensitivity analysis was carried out to check basic operation. (4) In order to confirm the applicability of the developed THMC analysis code, we have carried out case analysis on 1-dimensional and 3-dimensional model which including vitrified waste, over-pack, buffer material and rock in the HLW near-field. (author)

Repeated exposures to roadside particulate matter extracts suppresses pulmonary defense mechanisms, resulting in lipid and protein oxidative damage

International Nuclear Information System (INIS)

Pardo, Michal; Porat, Ziv; Rudich, Assaf; Schauer, James J.; Rudich, Yinon

2016-01-01

Exposure to particulate matter (PM) pollution in cities and urban canyons can be harmful to the exposed population. However, the underlying mechanisms that lead to health effects are not yet elucidated. It is postulated that exposure to repeated, small, environmentally relevant concentrations can affect lung homeostasis. This study examines the impact of repeated exposures to urban PM on mouse lungs with focus on inflammatory and oxidative stress parameters. Aqueous extracts from collected urban PM were administered to mice by 5 repeated intra-tracheal instillations (IT). Multiple exposures, led to an increase in cytokine levels in both bronchoalveolar lavage fluid and in the blood serum, indicating a systemic reaction. Lung mRNA levels of antioxidant/phase II detoxifying enzymes decreased by exposure to the PM extract, but not when metals were removed by chelation. Finally, disruption of lung tissue oxidant-inflammatory/defense balance was evidenced by increased levels of lipid and protein oxidation. Unlike response to a single IT exposure to the same dose and source of extract, multiple exposures result in lung oxidative damage and a systemic inflammatory reaction. These could be attributed to compromised capacity to activate the protective Nrf2 tissue defense system. It is suggested that water-soluble metals present in urban PM, potentially from break and tire wear, may constitute major drivers of the pulmonary and systemic responses to multiple exposure to urban PM. - Highlights: • Repeated exposure to urban PM cause systemic inflammation and oxidative damage to lung tissue lipids and proteins. • Repeated exposure to these PM extracts decreased transcription of Nrf2 protective genes. • Single as opposed to repeated exposure, induced confined lung response accompanied by activated defense mechanisms. • Metals, potentially from break and tire wear, drive the pulmonary response with exposure to urban PM. - Repeated exposures to urban PM water extracts

Better with Byzantine: Manipulation-Optimal Mechanisms

Science.gov (United States)

Othman, Abraham; Sandholm, Tuomas

A mechanism is manipulable if it is in some agents’ best interest to misrepresent their private information. The revelation principle establishes that, roughly, anything that can be accomplished by a manipulable mechanism can also be accomplished with a truthful mechanism. Yet agents often fail to play their optimal manipulations due to computational limitations or various flavors of incompetence and cognitive biases. Thus, manipulable mechanisms in particular should anticipate byzantine play. We study manipulation-optimal mechanisms: mechanisms that are undominated by truthful mechanisms when agents act fully rationally, and do better than any truthful mechanism if any agent fails to act rationally in any way. This enables the mechanism designer to do better than the revelation principle would suggest, and obviates the need to predict byzantine agents’ irrational behavior. We prove a host of possibility and impossibility results for the concept which have the impression of broadly limiting possibility. These results are largely in line with the revelation principle, although the considerations are more subtle and the impossibility not universal.

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact

Science.gov (United States)

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-01

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from ‘electrochemical’ to ‘mechanical’, which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

Mechanics of fiber reinforced materials

Science.gov (United States)

Sun, Huiyu

This dissertation is dedicated to mechanics of fiber reinforced materials and the woven reinforcement and composed of four parts of research: analytical characterization of the interfaces in laminated composites; micromechanics of braided composites; shear deformation, and Poisson's ratios of woven fabric reinforcements. A new approach to evaluate the mechanical characteristics of interfaces between composite laminae based on a modified laminate theory is proposed. By including an interface as a special lamina termed the "bonding-layer" in the analysis, the mechanical properties of the interfaces are obtained. A numerical illustration is given. For micro-mechanical properties of three-dimensionally braided composite materials, a new method via homogenization theory and incompatible multivariable FEM is developed. Results from the hybrid stress element approach compare more favorably with the experimental data than other existing numerical methods widely used. To evaluate the shearing properties for woven fabrics, a new mechanical model is proposed during the initial slip region. Analytical results show that this model provides better agreement with the experiments for both the initial shear modulus and the slipping angle than the existing models. Finally, another mechanical model for a woven fabric made of extensible yarns is employed to calculate the fabric Poisson's ratios. Theoretical results are compared with the available experimental data. A thorough examination on the influences of various mechanical properties of yarns and structural parameters of fabrics on the Poisson's ratios of a woven fabric is given at the end.

Distortion of frontal bones results from cell apoptosis by the mechanical force from the up-migrating eye during metamorphosis in Paralichthys olivaceus.

Science.gov (United States)

Sun, Mingyan; Wei, Fen; Li, Hui; Xu, Juan; Chen, Xinye; Gong, Xiaoling; Tian, Yongsheng; Chen, Songlin; Bao, Baolong

2015-05-01

Craniofacial remodeling during flatfish metamorphosis, including eye migration, is perhaps the most striking example of asymmetric postembryonic development in the vertebrate world. The asymmetry of the cranium mainly results from distortion of the frontal bones, which depends on eye migration during metamorphosis. However, it is unclear how the up-migrating eye causes distortion of the frontal bones. In this study, we first show that distortion of the frontal bones during metamorphosis in Paralichthys olivaceus is the result of cell apoptosis, rather than cell autophagy or cell proliferation. Secondly, we report that cell apoptosis in the frontal bones is induced by the mechanical force transferred from the up-migrating eye. The mechanical force from the up-migrating eye signals through FAK to downstream molecules that are integrated into the BMP-2 signal pathway. Finally, it is shown that cell apoptosis in the frontal bones is activated by the intrinsic mitochondrial pathway; the extrinsic death receptor is not involved in this process. Moreover, cell apoptosis in frontal bones is not induced directly by thyroid hormones, which are thought to mediate metamorphosis in flatfishes and directly mediate cell apoptosis during amphibian metamorphosis. These findings help identify the major signaling route used during regulation of frontal bone distortion during metamorphosis in flatfish, and indicate that the asymmetry of the cranium, or at least the distortion of frontal bones, is the result of rather than the reason underlying eye migration. Copyright © 2015. Published by Elsevier Ireland Ltd.

Supersymmetric mechanics

International Nuclear Information System (INIS)

Stelle, Kellogg S

2007-01-01

With the development of the electronic archives in high-energy physics, there has been increasing questioning of the role of traditional publishing styles, particularly in the production of conference books. One aspect of traditional publishing that still receives wide appreciation, however, is in the production of well-focussed pedagogical material. The present two-volume edition, 'Supersymmetric Mechanics-Vol 1', edited by S Bellucci and 'Supersymmetric Mechanics-Vol 2', edited by S Bellucci, S Ferrara and A Marrani, is a good example of the kind of well-digested presentation that should still find its way into university libraries. This two-volume set presents the material of a set of pedagogical lectures presented at the INFN National Laboratory in Frascati over a two-year period on the subject of supersymmetric mechanics. The articles include the results of discussions with the attending students after the lectures. Overall, this makes for a useful compilation of material on a subject that underlies much of the current effort in supersymmetric approaches to cosmology and the unification programme. The first volume comprises articles on 'A journey through garden algebras' by S Bellucci, S J Gates Jr and E Orazi on linear supermultiplet realizations in supersymmetric mechanics,'Supersymmetric mechanics in superspace' by S Bellucci and S Krivonos, 'Noncommutative mechanics, Landau levels, twistors and Yang-Mills amplitudes' by V P Nair, 'Elements of (super) Hamiltonian formalism' by A Nersessian and 'Matrix mechanics' by C Sochichiu. The second volume consists entirely of a masterful presentation on 'The attractor mechanism and space time singularities' by S Ferrara. This presents a comprehensive and detailed overview of the structure of supersymmetric black hole solutions in supergravity, critical point structure in the scalar field moduli space and the thermodynamic consequences. This second volume alone makes the set a worthwhile addition to the research

Reduced chemical kinetic mechanisms for hydrocarbon fuels

International Nuclear Information System (INIS)

Montgomery, C.J.; Cremer, M.A.; Heap, M.P.; Chen, J-Y.; Westbrook, C.K.; Maurice, L.Q.

1999-01-01

Using CARM (Computer Aided Reduction Method), a computer program that automates the mechanism reduction process, a variety of different reduced chemical kinetic mechanisms for ethylene and n-heptane have been generated. The reduced mechanisms have been compared to detailed chemistry calculations in simple homogeneous reactors and experiments. Reduced mechanisms for combustion of ethylene having as few as 10 species were found to give reasonable agreement with detailed chemistry over a range of stoichiometries and showed significant improvement over currently used global mechanisms. The performance of reduced mechanisms derived from a large detailed mechanism for n-heptane was compared to results from a reduced mechanism derived from a smaller semi-empirical mechanism. The semi-empirical mechanism was advantageous as a starting point for reduction for ignition delay, but not for PSR calculations. Reduced mechanisms with as few as 12 species gave excellent results for n-heptane/air PSR calculations but 16-25 or more species are needed to simulate n-heptane ignition delay

Mechanism of laser micro-adjustment

International Nuclear Information System (INIS)

Shen Hong

2008-01-01

Miniaturization is a requirement in engineering to produce competitive products in the field of optical and electronic industries. Laser micro-adjustment is a new and promising technology for sheet metal actuator systems. Efforts have been made to understand the mechanisms of metal plate forming using a laser heating source. Three mechanisms have been proposed for describing the laser forming processes in different scenarios, namely the temperature gradient mechanism (TGM), buckling mechanism and upsetting mechanism (UM). However, none of these mechanisms can fully describe the deformation mechanisms involved in laser micro-adjustment. Based on the thermal and elastoplastic analyses, a coupled TGM and UM are presented in this paper to illustrate the thermal mechanical behaviours of two-bridge actuators when applying a laser forming process. To validate the proposed coupling mechanism, numerical simulations are carried out and the corresponding results demonstrate the mechanism proposed. The mechanism of the micro-laser adjustment could be taken as a supplement to the laser forming process.

Preliminary study for the reliability Assurance on results and procedure of the out-pile mechanical characterization test for a fuel assembly; Lateral Vibration Test (I)

Energy Technology Data Exchange (ETDEWEB)

Lee, Kang Hee; Yoon, Kyung Hee; Kim, Hyung Kyu [KAERI, Daejeon (Korea, Republic of)

2007-07-01

The reliability assurance with respect to the test procedure and results of the out-pile mechanical performance test for the nuclear fuel assembly is an essential task to assure the test quality and to get a permission for fuel loading into the commercial reactor core. For the case of vibration test, proper management and appropriate calibration of instruments and devices used in the test, various efforts to minimize the possible error during the test and signal acquisition process are needed. Additionally, the deep understanding both of the theoretical assumption and simplification for the signal processing/modal analysis and of the functions of the devices used in the test were highly required. In this study, the overall procedure and result of lateral vibration test were assembly's mechanical characterization were briefly introduced. A series of measures to assure and improve the reliability of the vibration test were discussed.

Preliminary study for the reliability Assurance on results and procedure of the out-pile mechanical characterization test for a fuel assembly; Lateral Vibration Test (I)

International Nuclear Information System (INIS)

Lee, Kang Hee; Yoon, Kyung Hee; Kim, Hyung Kyu

2007-01-01

The reliability assurance with respect to the test procedure and results of the out-pile mechanical performance test for the nuclear fuel assembly is an essential task to assure the test quality and to get a permission for fuel loading into the commercial reactor core. For the case of vibration test, proper management and appropriate calibration of instruments and devices used in the test, various efforts to minimize the possible error during the test and signal acquisition process are needed. Additionally, the deep understanding both of the theoretical assumption and simplification for the signal processing/modal analysis and of the functions of the devices used in the test were highly required. In this study, the overall procedure and result of lateral vibration test were assembly's mechanical characterization were briefly introduced. A series of measures to assure and improve the reliability of the vibration test were discussed

Mechanical and electro-mechanical properties of three-dimensional nanoporous graphene-poly(vinylidene fluoride composites

Directory of Open Access Journals (Sweden)

G. P. Zheng

2016-09-01

Full Text Available Three-dimensional nanoporous graphene monoliths are utilized to prepare graphene-poly(vinylidene fluoride nanocomposites with enhanced mechanical and electro-mechanical properties. Pre-treatment of the polymer (poly(vinylidene fluoride, PVDF with graphene oxides (GOs facilitates the formation of uniform and thin PVDF films with a typical thickness below 100 nm well coated at the graphene nano-sheets. Besides their excellent compressibility, ductility and mechanical strength, the nanoporous graphene-PVDF nanocomposites are found to possess high sensitivity in strain-dependent electrical conductivity. The improved mechanical and electro-mechanical properties are ascribed to the enhanced crystalline β phase in PVDF which possesses piezoelectricity. The mechanical relaxation analyses on the interfaces between graphene and PVDF reveal that the improved mechanical and electro-mechanical properties could result from the interaction between the –C=O groups in the nanoporous graphene and the –CF2 groups in PVDF, which also explains the important role of GOs in the preparation of the graphene-polymer nanocomposites with superior combined mechanical and electro-mechanical properties.

Testing Nonassociative Quantum Mechanics.

Science.gov (United States)

Bojowald, Martin; Brahma, Suddhasattwa; Büyükçam, Umut

2015-11-27

The familiar concepts of state vectors and operators in quantum mechanics rely on associative products of observables. However, these notions do not apply to some exotic systems such as magnetic monopoles, which have long been known to lead to nonassociative algebras. Their quantum physics has remained obscure. This Letter presents the first derivation of potentially testable physical results in nonassociative quantum mechanics, based on effective potentials. They imply new effects which cannot be mimicked in usual quantum mechanics with standard magnetic fields.

Determination of efficiencies, loss mechanisms, and performance degradation factors in chopper controlled dc vehical motors. Section 1: Test program results and recommendations

Science.gov (United States)

Hamilton, H. B.; Strangas, E.

1980-01-01

The conventional series motor model is discussed as well as procedures for obtaining, by test, the parameters necessary for calculating performance and losses. The calculated results for operation from ripple free DC are compared with observed test results, indicating approximately 5% or less error. Experimental data indicating the influence of brush shift and chopper frequency are also presented. Both factors have a significant effect on the speed and torque relationships. The losses and loss mechanisms present in a DC series motor are examined and an attempt is made to evaluate the added losses due to harmonic currents and fluxes. Findings with respect to these losses is summarized.

The mechanical response of a PBX and binder: combining results across the strain-rate and frequency domains

International Nuclear Information System (INIS)

Drodge, D R; Williamson, D M; Palmer, S J P; Proud, W G; Govier, R K

2010-01-01

The mechanical response of a polymer bonded explosive (PBX) has been measured using a Split Hopkinson Pressure Bar at a strain-rate of 2000 s -1 , across a range of temperatures from 173 to 333 K, with the aim of observing its behaviour in the glassy regime. The yield stresses increased monotonically with decreasing temperature and no plateau was found. The failure mechanism was found to transition from shear-banding with crystal debonding fracture to brittle failure with some evidence of crystal fracture. Similar experiments were performed on samples of its nitrocellulose-based binder material, at a strain-rate of 3000 s -1 across a temperature range 173-273 K. The failure stresses of the binder approach that of the composite at temperatures near -70 0 C. The elastic moduli were estimated from post-equilibrium regions of the stress-strain curves, and compared with those obtained for the composite using 5 MHz ultrasonic sound-speed measurement, and powder dynamic mechanical analysis measurements and quasi-static behaviour reported in a previous paper. The moduli were plotted on a common frequency axis: a temperature shift was applied to collapse the curves, which agreed with the Cox-Merz rule.

Quantum mechanics/coarse-grained molecular mechanics (QM/CG-MM).

Science.gov (United States)

Sinitskiy, Anton V; Voth, Gregory A

2018-01-07

Numerous molecular systems, including solutions, proteins, and composite materials, can be modeled using mixed-resolution representations, of which the quantum mechanics/molecular mechanics (QM/MM) approach has become the most widely used. However, the QM/MM approach often faces a number of challenges, including the high cost of repetitive QM computations, the slow sampling even for the MM part in those cases where a system under investigation has a complex dynamics, and a difficulty in providing a simple, qualitative interpretation of numerical results in terms of the influence of the molecular environment upon the active QM region. In this paper, we address these issues by combining QM/MM modeling with the methodology of "bottom-up" coarse-graining (CG) to provide the theoretical basis for a systematic quantum-mechanical/coarse-grained molecular mechanics (QM/CG-MM) mixed resolution approach. A derivation of the method is presented based on a combination of statistical mechanics and quantum mechanics, leading to an equation for the effective Hamiltonian of the QM part, a central concept in the QM/CG-MM theory. A detailed analysis of different contributions to the effective Hamiltonian from electrostatic, induction, dispersion, and exchange interactions between the QM part and the surroundings is provided, serving as a foundation for a potential hierarchy of QM/CG-MM methods varying in their accuracy and computational cost. A relationship of the QM/CG-MM methodology to other mixed resolution approaches is also discussed.

Quantum mechanics/coarse-grained molecular mechanics (QM/CG-MM)

Science.gov (United States)

Sinitskiy, Anton V.; Voth, Gregory A.

2018-01-01

Numerous molecular systems, including solutions, proteins, and composite materials, can be modeled using mixed-resolution representations, of which the quantum mechanics/molecular mechanics (QM/MM) approach has become the most widely used. However, the QM/MM approach often faces a number of challenges, including the high cost of repetitive QM computations, the slow sampling even for the MM part in those cases where a system under investigation has a complex dynamics, and a difficulty in providing a simple, qualitative interpretation of numerical results in terms of the influence of the molecular environment upon the active QM region. In this paper, we address these issues by combining QM/MM modeling with the methodology of "bottom-up" coarse-graining (CG) to provide the theoretical basis for a systematic quantum-mechanical/coarse-grained molecular mechanics (QM/CG-MM) mixed resolution approach. A derivation of the method is presented based on a combination of statistical mechanics and quantum mechanics, leading to an equation for the effective Hamiltonian of the QM part, a central concept in the QM/CG-MM theory. A detailed analysis of different contributions to the effective Hamiltonian from electrostatic, induction, dispersion, and exchange interactions between the QM part and the surroundings is provided, serving as a foundation for a potential hierarchy of QM/CG-MM methods varying in their accuracy and computational cost. A relationship of the QM/CG-MM methodology to other mixed resolution approaches is also discussed.

From wave mechanics to quantum chemistry

International Nuclear Information System (INIS)

Daudel, R.

1996-01-01

The origin of wave mechanics, which is now called quantum mechanics, is evoked. The main stages of the birth of quantum chemistry are related as resulting from the application of quantum mechanics to the study of molecular properties and chemical reactions. (author). 14 refs

Transient thermal-mechanical coupling behavior analysis of mechanical seals during start-up operation

Science.gov (United States)

Gao, B. C.; Meng, X. K.; Shen, M. X.; Peng, X. D.

2016-05-01

A transient thermal-mechanical coupling model for a contacting mechanical seal during start-up has been developed. It takes into consideration the coupling relationship among thermal-mechanical deformation, film thickness, temperature and heat generation. The finite element method and multi-iteration technology are applied to solve the temperature distribution and thermal-mechanical deformation as well as their evolution behavior. Results show that the seal gap transforms from negative coning to positive coning and the contact area of the mechanical seal gradually decreases during start-up. The location of the maximum temperature and maximum contact pressure move from the outer diameter to inside diameter. The heat generation and the friction torque increase sharply at first and then decrease. Meanwhile, the contact force decreases and the fluid film force and leakage rate increase.

Surface Damage Mechanism of Monocrystalline Si Under Mechanical Loading

Science.gov (United States)

Zhao, Qingliang; Zhang, Quanli; To, Suet; Guo, Bing

2017-03-01

Single-point diamond scratching and nanoindentation on monocrystalline silicon wafer were performed to investigate the surface damage mechanism of Si under the contact loading. The results showed that three typical stages of material removal appeared during dynamic scratching, and a chemical reaction of Si with the diamond indenter and oxygen occurred under the high temperature. In addition, the Raman spectra of the various points in the scratching groove indicated that the Si-I to β-Sn structure (Si-II) and the following β-Sn structure (Si-II) to amorphous Si transformation appeared under the rapid loading/unloading condition of the diamond grit, and the volume change induced by the phase transformation resulted in a critical depth (ductile-brittle transition) of cut (˜60 nm ± 15 nm) much lower than the theoretical calculated results (˜387 nm). Moreover, it also led to abnormal load-displacement curves in the nanoindentation tests, resulting in the appearance of elbow and pop-out effects (˜270 nm at 20 s, 50 mN), which were highly dependent on the loading/unloading conditions. In summary, phase transformation of Si promoted surface deformation and fracture under both static and dynamic mechanical loading.

Classicality in quantum mechanics

Energy Technology Data Exchange (ETDEWEB)

Dreyer, Olaf [Theoretical Physics, Blackett Laboratory, Imperial College London, London, SW7 2AZ (United Kingdom)

2007-05-15

In this article we propose a solution to the measurement problem in quantum mechanics. We point out that the measurement problem can be traced to an a priori notion of classicality in the formulation of quantum mechanics. If this notion of classicality is dropped and instead classicality is defined in purely quantum mechanical terms the measurement problem can be avoided. We give such a definition of classicality. It identifies classicality as a property of large quantum system. We show how the probabilistic nature of quantum mechanics is a result of this notion of classicality. We also comment on what the implications of this view are for the search of a quantum theory of gravity.

Classicality in quantum mechanics

International Nuclear Information System (INIS)

Dreyer, Olaf

2007-01-01

In this article we propose a solution to the measurement problem in quantum mechanics. We point out that the measurement problem can be traced to an a priori notion of classicality in the formulation of quantum mechanics. If this notion of classicality is dropped and instead classicality is defined in purely quantum mechanical terms the measurement problem can be avoided. We give such a definition of classicality. It identifies classicality as a property of large quantum system. We show how the probabilistic nature of quantum mechanics is a result of this notion of classicality. We also comment on what the implications of this view are for the search of a quantum theory of gravity

Determination of the mechanical characteristics of irradiated metals from the results of microhardness tests

International Nuclear Information System (INIS)

Hofman, A.

1999-01-01

To predict the possibilities of using structural materials in nuclear and thermonuclear reactors, it is important to have data on changes of the mechanical characteristics and irradiation obtained from full-scale or simulation tests. Materials are irradiated in nuclear reactors with fast neutrons, the sources of high-energy neutrons with an energy of 14 MeV and the accelerators of charged particles. The restricted volumes for irradiation of these specimens in the systems and also the need to test large numbers of specimens under the same conditions make it necessary to reduce the size of irradiated specimens. To solve this problem, work is being carried out to develop various methods of testing miniature specimens, including tension extrusion of disc-shaped micro-specimens, microhardness, and the Charpy Method. In examination of the irradiation hardening of the materials, the main advantage of the microhardness method is that it makes it possible to examine small specimens. In single microhardness tests, only a small area of the irradiated specimens is examined. This makes it possible to increase the radiation dose and carry out subsequent tests of microhardness on the same specimens. The aim of this work was to determine the possibilities of using the microhardness measurement method for evaluating the mechanical characteristics of metallic materials. The comparison of the data, obtained in microhardness tests and in tensile loading specimens of 0Kh18N10Tsteel, irradiated with neutrons, shows the efficiency of the microhardness method as a tool for investigating the irradiation hardening of reactor materials

The physio-mechanical

Directory of Open Access Journals (Sweden)

C.U. Atuanya

2014-01-01

Full Text Available This work presents a systematic approach to evaluate the physio-mechanical properties of bean pod ash particles (BPAp reinforced recycled polyethylene (RLDPE polymer based composites. The bean pod ash particles of 75 μm with a weight percentage of 0, 5, 10, 15, 20, 25, 30 (wt% and recycled polyethylene (RLDPE were prepared. The surface morphology, physical and the mechanical properties of the composites were examined. The results showed that the fair distribution of the bean pod ash particles in the microstructure of the polymer composites is the major factor responsible for the improvement in the mechanical properties. The bean pod ash particles added to the RLDPE polymer increased the percentage of water absorption and improved its rigidity, modulus and hardness values of the composites. The tensile and flexural strengths increased to a maximum of 20.1 and 39.0 N/mm2 at 20 wt% BPAp respectively. Based on the results obtained in this study, it is recommended that the composites can be used in the production of indoor and outdoor applications.

Mechanical stability of heat-treated nanoporous anodic alumina subjected to repetitive mechanical deformation

Science.gov (United States)

Bankova, A.; Videkov, V.; Tzaneva, B.; Mitov, M.

2018-03-01

We report studies on the mechanical response and deformation behavior of heat-treated nanoporous anodic alumina using a micro-balance test and experimental test equipment especially designed for this purpose. AAO samples were characterized mechanically by a three-point bending test using a micro-analytical balance. The deformation behavior was studied by repetitive mechanical bending of the AAO membranes using an electronically controlled system. The nanoporous AAO structures were prepared electrochemically from Al sheet substrates using a two-step anodizing technique in oxalic acid followed by heat treatment at 700 °C in air. The morphological study of the aluminum oxide layer after the mechanical tests and mechanical deformation was conducted using scanning electron and optical microscopy, respectively. The experimental results showed that the techniques proposed are simple and accurate; they could, therefore, be combined to constitute a method for mechanical stability assessment of nanostructured AAO films, which are important structural components in the design of MEMS devices and sensors.

Prediction of mechanical properties for hexagonal boron nitride nanosheets using molecular mechanics model

Energy Technology Data Exchange (ETDEWEB)

Natsuki, Toshiaki [Shinshu University, Faculty of Textile Science and Technology, Ueda (Japan); Shinshu University, Institute of Carbon Science and Technology, Nagano (Japan); Natsuki, Jun [Shinshu University, Institute of Carbon Science and Technology, Nagano (Japan)

2017-04-15

Mechanical behaviors of nanomaterials are not easy to be evaluated in the laboratory because of their extremely small size and difficulty controlling. Thus, a suitable model for the estimation of the mechanical properties for nanomaterials becomes very important. In this study, the elastic properties of boron nitride (BN) nanosheets, including the elastic modulus, the shear modulus, and the Poisson's ratio, are predicted using a molecular mechanics model. The molecular mechanics force filed is established to directly incorporate the Morse potential function into the constitutive model of nanostructures. According to the molecular mechanics model, the chirality effect of hexagonal BN nanosheets on the elastic modulus is investigated through a closed-form solution. The simulated result shows that BN nanosheets exhibit an isotropic elastic property. The present analysis yields a set of very simple formulas and is able to be served as a good approximation on the mechanical properties for the BN nanosheets. (orig.)

Prediction of mechanical properties for hexagonal boron nitride nanosheets using molecular mechanics model

International Nuclear Information System (INIS)

Natsuki, Toshiaki; Natsuki, Jun

2017-01-01

Mechanical behaviors of nanomaterials are not easy to be evaluated in the laboratory because of their extremely small size and difficulty controlling. Thus, a suitable model for the estimation of the mechanical properties for nanomaterials becomes very important. In this study, the elastic properties of boron nitride (BN) nanosheets, including the elastic modulus, the shear modulus, and the Poisson's ratio, are predicted using a molecular mechanics model. The molecular mechanics force filed is established to directly incorporate the Morse potential function into the constitutive model of nanostructures. According to the molecular mechanics model, the chirality effect of hexagonal BN nanosheets on the elastic modulus is investigated through a closed-form solution. The simulated result shows that BN nanosheets exhibit an isotropic elastic property. The present analysis yields a set of very simple formulas and is able to be served as a good approximation on the mechanical properties for the BN nanosheets. (orig.)

Sampling Molecular Conformers in Solution with Quantum Mechanical Accuracy at a Nearly Molecular-Mechanics Cost.

Science.gov (United States)

Rosa, Marta; Micciarelli, Marco; Laio, Alessandro; Baroni, Stefano

2016-09-13

We introduce a method to evaluate the relative populations of different conformers of molecular species in solution, aiming at quantum mechanical accuracy, while keeping the computational cost at a nearly molecular-mechanics level. This goal is achieved by combining long classical molecular-dynamics simulations to sample the free-energy landscape of the system, advanced clustering techniques to identify the most relevant conformers, and thermodynamic perturbation theory to correct the resulting populations, using quantum-mechanical energies from density functional theory. A quantitative criterion for assessing the accuracy thus achieved is proposed. The resulting methodology is demonstrated in the specific case of cyanin (cyanidin-3-glucoside) in water solution.

Performance assessment of semiempirical molecular orbital methods in describing halogen bonding: quantum mechanical and quantum mechanical/molecular mechanical-molecular dynamics study.

Science.gov (United States)

Ibrahim, Mahmoud A A

2011-10-24

The performance of semiempirical molecular-orbital methods--MNDO, MNDO-d, AM1, RM1, PM3 and PM6--in describing halogen bonding was evaluated, and the results were compared with molecular mechanical (MM) and quantum mechanical (QM) data. Three types of performance were assessed: (1) geometrical optimizations and binding energy calculations for 27 halogen-containing molecules complexed with various Lewis bases (Two of the tested methods, AM1 and RM1, gave results that agree with the QM data.); (2) charge distribution calculations for halobenzene molecules, determined by calculating the solvation free energies of the molecules relative to benzene in explicit and implicit generalized Born (GB) solvents (None of the methods gave results that agree with the experimental data.); and (3) appropriateness of the semiempirical methods in the hybrid quantum-mechanical/molecular-mechanical (QM/MM) scheme, investigated by studying the molecular inhibition of CK2 protein by eight halobenzimidazole and -benzotriazole derivatives using hybrid QM/MM molecular-dynamics (MD) simulations with the inhibitor described at the QM level by the AM1 method and the rest of the system described at the MM level. The pure MM approach with inclusion of an extra point of positive charge on the halogen atom approach gave better results than the hybrid QM/MM approach involving the AM1 method. Also, in comparison with the pure MM-GBSA (generalized Born surface area) binding energies and experimental data, the calculated QM/MM-GBSA binding energies of the inhibitors were improved by replacing the G(GB,QM/MM) solvation term with the corresponding G(GB,MM) term.

Mechanical behaviour of nanoparticles: Elasticity and plastic ...

Indian Academy of Sciences (India)

2015-06-03

Jun 3, 2015 ... Mechanical behaviour of nanoparticles: Elasticity and plastic deformation mechanisms ... The main results in terms of elasticity and plastic deformation mechanisms are then reported ... Pramana – Journal of Physics | News.

Microstructures and formation mechanism of W–Cu composite coatings on copper substrate prepared by mechanical alloying method

International Nuclear Information System (INIS)

Meng, Yunfei; Shen, Yifu; Chen, Cheng; Li, Yongcan; Feng, Xiaomei

2013-01-01

In the present work, high-energy mechanical alloying (MA) method was applied to prepare tungsten–copper composite coatings on pure copper surface using a planetary ball mill. During mechanical alloying process, grains on the surface layer of substrate were refined and the substrate surface was activated as a result of repeated collisions by a large number of flying balls along with powder particles. The repeated ball-to-substrate collisions resulted in the deposition of coatings. The microstructures and elemental and phase composition of mechanically alloyed coatings at different milling durations during mechanical alloying process were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS). Microhardness tests were carried out to examine the mechanical properties of the coatings. The results showed that the coatings and the substrates were well bonded, and with the increase of the milling duration, multi-layered coatings with different structures were generated and the coatings became denser. The microhardness tests showed that the maximum microhardness of the coatings reached HV 0.1 228, showing a threefold improvement upon the substrate. And the cross-sectional microhardness values of the processed sample changed gradually, which gave a proof for the cushioning and sustaining functions of the multi-layered coatings. A reasonable formation mechanism of coatings on bulk materials with metallic immiscible system by mechanical alloying method was presented.

Shale Failure Mechanics and Intervention Measures in Underground Coal Mines: Results From 50 Years of Ground Control Safety Research

Science.gov (United States)

2015-01-01

Ground control research in underground coal mines has been ongoing for over 50 years. One of the most problematic issues in underground coal mines is roof failures associated with weak shale. This paper will present a historical narrative on the research the National Institute for Occupational Safety and Health has conducted in relation to rock mechanics and shale. This paper begins by first discussing how shale is classified in relation to coal mining. Characterizing and planning for weak roof sequences is an important step in developing an engineering solution to prevent roof failures. Next, the failure mechanics associated with the weak characteristics of shale will be discussed. Understanding these failure mechanics also aids in applying the correct engineering solutions. The various solutions that have been implemented in the underground coal mining industry to control the different modes of failure will be summarized. Finally, a discussion on current and future research relating to rock mechanics and shale is presented. The overall goal of the paper is to share the collective ground control experience of controlling roof structures dominated by shale rock in underground coal mining. PMID:26549926

New Physical Mechanism for Lightning

Science.gov (United States)

Artekha, Sergey N.; Belyan, Andrey V.

2018-02-01

The article is devoted to electromagnetic phenomena in the atmosphere. The set of experimental data on the thunderstorm activity is analyzed. It helps to identify a possible physical mechanism of lightning flashes. This mechanism can involve the formation of metallic bonds in thunderclouds. The analysis of the problem is performed at a microphysical level within the framework of quantum mechanics. The mechanism of appearance of metallic conductivity includes the resonant tunneling of electrons along resonance-percolation trajectories. Such bonds allow the charges from the vast cloud charged subsystems concentrate quickly in lightning channel. The formation of metal bonds in the thunderstorm cloudiness is described as the second-order phase transition. A successive mechanism for the process of formation and development of the lightning channel is suggested. This mechanism is associated with the change in the orientation of crystals in growing electric field. Possible consequences of the quantum-mechanical mechanism under discussion are compared with the results of observations.

Thermo-mechanical ratcheting in jointed rock masses

KAUST Repository

Pasten, C.

2015-09-01

Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

Thermo-mechanical ratcheting in jointed rock masses

KAUST Repository

Pasten, C.; Garcí a, M.; Santamarina, Carlos

2015-01-01

Thermo-mechanical coupling takes place in jointed rock masses subjected to large thermal oscillations. Examples range from exposed surfaces under daily and seasonal thermal fluctuations to subsurface rock masses affected by engineered systems such as geothermal operations. Experimental, numerical and analytical results show that thermo-mechanical coupling can lead to wedging and ratcheting mechanisms that result in deformation accumulation when the rock mass is subjected to a biased static-force condition. Analytical and numerical models help in identifying the parameter domain where thermo-mechanical ratcheting can take place.

A study on thermal and mechanical properties of mechanically milled HDPE and PP

International Nuclear Information System (INIS)

Can, S.; Tan, S.

2003-01-01

In this study, mechanical mixing of HDPE and PP was performed via ball milling. Prepared compositions were 75/25 , 50/50 , 25/75 w/w HDPE/PP. Milling time and ball to powder ratio (B/P) were kept constant and system was cooled by adding solid CO 2 to improve the milling efficiency. To compare these systems with traditional methods, mixtures were also melt mixed by Brabender Plasti-Corder. Both milled and melt mixed systems were examined with DSC for thermal properties and tensile testing for mechanical properties Results are discussed by comparing milled , melt mixed and as-received polymers. It is observed that, unlike ball milled systems' in melt mixed systems mechanical properties are composition dependent. In addition , ball milling results in amorphization of both polymers and very high amounts of PP (75wt %) creates very amorphous HDPE structure. (Original)

Development and Validation of Chemical Kinetic Mechanism Reduction Scheme for Large-Scale Mechanisms

DEFF Research Database (Denmark)

Poon, Hiew Mun; Ng, Hoon Kiat; Gan, Suyin

2014-01-01

This work is an extension to a previously reported work on chemical kinetic mechanism reduction scheme for large-scale mechanisms. Here, Perfectly Stirred Reactor (PSR) was added as a criterion of data source for mechanism reduction instead of using only auto-ignition condition. As a result......) simulations were performed to study the spray combustion phenomena within a constant volume bomb. Both non-reacting and reacting conditions were applied in this study. Liquid and vapor penetration lengths were replicated for non-reacting diesel spray. For reacting diesel spray, both ignition delay and lift......-off length were simulated. The simulation results were then compared to the experimental data of Sandia National Laboratories and No. 2 Diesel Fuel (D2) was designated as the reference fuel. Both liquid and vapor penetrations for non-reacting condition were well-matched, while ignition delay was advanced...

Multiscale mechanics of TRIP-assisted multiphase steels: I. Characterization and mechanical testing

International Nuclear Information System (INIS)

Jacques, P.J.; Furnemont, Q.; Lani, F.; Pardoen, T.; Delannay, F.

2007-01-01

The mechanical behaviour of transformation-induced plasticity (TRIP)-assisted multiphase steels is addressed based on three different microstructures generated from the same steel grade. The mechanisms responsible for the work-hardening capacity and the resulting balance between strength and resistance to plastic localization are investigated at different length scales. The macroscopic mechanical response is determined by simple shear, uniaxial tension, Marciniak and equibiaxial tension supplemented by earlier tensile tests on notched and cracked specimens. It is shown that the transformation rate reaches a maximum for stress states intermediate between uniaxial tension and equibiaxial tension. At an intermediate length scale, the true in situ flow properties of the individual ferrite-bainite and retained austenite phases are determined by combining neutron diffraction and digital image correlation. This combined analysis elucidates the partitioning of stress and strain between the different constitutive phases. Based on these results, supplemented by transmission electron microscopy and electron backscattered diffraction observations, a general overview of the hardening behaviour of TRIP-assisted multiphase steels is depicted

Mathematical modelling in solid mechanics

CERN Document Server

Sofonea, Mircea; Steigmann, David

2017-01-01

This book presents new research results in multidisciplinary fields of mathematical and numerical modelling in mechanics. The chapters treat the topics: mathematical modelling in solid, fluid and contact mechanics nonconvex variational analysis with emphasis to nonlinear solid and structural mechanics numerical modelling of problems with non-smooth constitutive laws, approximation of variational and hemivariational inequalities, numerical analysis of discrete schemes, numerical methods and the corresponding algorithms, applications to mechanical engineering numerical aspects of non-smooth mechanics, with emphasis on developing accurate and reliable computational tools mechanics of fibre-reinforced materials behaviour of elasto-plastic materials accounting for the microstructural defects definition of structural defects based on the differential geometry concepts or on the atomistic basis interaction between phase transformation and dislocations at nano-scale energetic arguments bifurcation and post-buckling a...

[Clinical Trial of Treatment of Cervicogenic Scapulohumeral Periarthritis by Red-hot Needle Therapy Combined with Cupping].

Science.gov (United States)

Yuan, Tao; Wang, Fen

2015-10-01

To observe the therapeutic effect of red-hot needle therapy combined with cupping for cervicogenic periarthritis of shoulder. Forty-two cases of cervicogenic periarthritis of shoulder were randomized into red-hot needle group and routine acupuncture group (n = 21). For patients of the routine acupuncture group, the filiform needles were applied to Tianzhu (BL 10), Jianjing (GB 21), Jianzhongshu (SI 15), Jianzhen (SI 9), Jianliao (TE 14), Jianyu (LI 15), Jianqian, Tianzong (SI 11) and Ashi-points on the affected side, followed by conducting cupping at the anterior and posterior regions of the affected shoulder, SI 11, GB 21 and SI 15. For patients of the red-hot needle group, the Ashi-points on the affected shoulder were punctured with cauterized filiform needles, following by performing cupping. The treatment was performed once daily and once every other day respectively for two weeks. The shoulder motor function was assessed according to the adjusted Constant-Murley test. After the treatment, the integrated scores of shoulder pain, shoulder-joint activities in daily living and shoulder-joint motion range were significantly increased in both groups compared with pre-treatment in the same one group (P therapy was significantly superior to that of the routine acupuncture (P therapy combined with cupping is effective in relieving cervicogenic shoulder periarthritis and is remarkably superior to routine acupuncture combined with cupping in improving shoulder periarthritis patients' symptoms.

Recent results from TASSO

International Nuclear Information System (INIS)

Foster, B.

1982-03-01

Results are presented on the inclusive production of π 0 , K 0 and antiK 0 and lambda and antilambda in e + e - annihilation. These results, together with those on inclusive charged hadron production are used to obtain information on fragmentation mechanisms and the production of heavy quark flavours in e + e - annihilation. (author)

Hydro-mechanical analysis of results acquired by video-observations and deformation measurements performed in boreholes in the Opalinus clay of the URL Mont Terri supported by laboratory investigations on the hydro-mechanical behaviour of Opalinus clay

International Nuclear Information System (INIS)

Seeska, R.; Rutenberg, M.; Lux, K.H.

2012-01-01

also be detected. Furthermore, a significant influence of the hydraulic behaviour on the load-bearing and deformation behaviour of the investigated boreholes was observed. Therefore, laboratory investigations regarding the hydraulic sensitivity of Opalinus Clay have been performed in the TUC rock mechanic laboratory on rock samples from the URL Mont Terri in addition to the in-situ observations. To investigate the hydraulic sensitivity and the hydro-mechanically coupled behaviour of the clay-stone samples, a series of uniaxial strength tests with precisely controlled relative humidity and temperature of the air surrounding the specimen inside the test rig has been performed. Eventually, an attempt has been made to hydro-mechanically model the observed borehole behaviour by using a three-dimensional model covering a drift section and a borehole within the near field of the drift. The numerical simulations have been performed using an elastoplastic constitutive model named ubiquitous joint. Implemented in the FLAC3D software code, the constitutive model ubiquitous joint is capable of modelling the mechanical behaviour of the rock matrix as well as the highly anisotropic mechanical behaviour of the bedding planes. Furthermore, effects like time dependent desaturation of the rock mass, a reduction of strength in the damaged zones around the drift and the borehole, and the increase of hydraulic permeability within the damaged zones have also been taken into consideration when performing the numerical simulations. Figure 2 exemplarily shows the calculated pore pressure distribution around the drift and the borehole in a cross section along the borehole's longitudinal axis. The presentation includes a brief discussion of the results obtained by the logging tool and the discussion of the borehole videos that were recorded by the axial borehole camera as well as a discussion of the laboratory results before in the concluding part the results of the numerical simulations will be

Social Welfare in One-Sided Matching Mechanisms

DEFF Research Database (Denmark)

Christodoulou, George; Filos-Ratsikas, Aris; Frederiksen, Søren Kristoffer Stiil

2016-01-01

We study the Price of Anarchy of mechanisms for the fundamental problem of social welfare maximization in one-sided matching settings, when agents have general cardinal preferences over a finite set of items. We consider both the complete and incomplete information settings and show that the two...... most well-studied mechanisms in literature, Probabilistic Serial and Random Priority have a Price of Anarchy of $O(\\sqrt{n})$. We complement our results with a lower bound of $\\Omega(\\sqrt{n})$ on the Price of Anarchy of \\emph{all} mechanisms. As a result, we conclude that these mechanisms are optimal....

U.S. Residential Miscellaneous Refrigeration Products: Results from Amazon Mechanical Turk Surveys

Energy Technology Data Exchange (ETDEWEB)

Greenblatt, Jeffery B.; Young, Scott J.; Yang, Hung-Chia; Long, Timothy; Beraki, Bereket; Price, Sarah K.; Pratt, Stacy; Willem, Henry; Desroches, Louis-Benoit

2013-11-14

Amazon Mechanical Turk was used, for the first time, to collect statistically representative survey data from U.S. households on the presence, number, type and usage of refrigerators, freezers, and various “miscellaneous” refrigeration products (wine/beverage coolers, residential icemakers and non-vapor compression refrigerators and freezers), along with household and demographic information. Such products have been poorly studied to date, with almost no information available about shipments, stocks, capacities, energy use, etc. A total of 9,981 clean survey responses were obtained from five distinct surveys deployed in 2012. General refrigeration product survey responses were weighted to demographics in the U.S. Energy Information Administration’s Residential Energy Consumption Survey 2009 dataset. Miscellaneous refrigeration product survey responses were weighted according to demographics of product ownership found in the general refrigeration product surveys. Model number matching for a portion of miscellaneous refrigeration product responses allowed validation of refrigeration product characteristics, which enabled more accurate estimates of the penetrations of these products in U.S. households. We estimated that there were 12.3±1.0 million wine/beverage coolers, 5.5(–3.5,+3.2) million residential icemakers and 4.4(–2.7,+2.3) million non-vapor compression refrigerators in U.S. households in 2012. (All numerical results are expressed with ranges indicating the 95% confidence interval.) No evidence was found for the existence of non-vapor compression freezers. Moreover, we found that 15% of wine/beverage coolers used vapor compression cooling technology, while 85% used thermoelectric cooling technology, with the vast majority of thermoelectric units having capacities of less than 30 wine bottles (approximately 3.5 cubic feet). No evidence was found for the existence of wine/beverage coolers with absorption cooling technology. Additionally, we estimated

U.S. Residential Miscellaneous Refrigeration Products: Results from Amazon Mechanical Turk Surveys

Energy Technology Data Exchange (ETDEWEB)

Greenblatt, Jeffery B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Young, Scott J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yang, Hung-Chia [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Long, Timothy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Beraki, Bereket [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Sarah K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pratt, Stacy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Willem, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Desroches, Louis-Benoit [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2013-04-01

Amazon Mechanical Turk was used, for the first time, to collect statistically representative survey data from U.S. households on the presence, number, type and usage of refrigerators, freezers, and various “miscellaneous” refrigeration products (wine/beverage coolers, residential icemakers and non-vapor compression refrigerators and freezers), along with household and demographic information. Such products have been poorly studied to date, with almost no information available about shipments, stocks, capacities, energy use, etc. A total of 9,820 clean survey responses were obtained from four distinct surveys deployed in 2012. General refrigeration product survey responses were weighted to demographics in the U.S. Energy Information Administration’s Residential Energy Consumption Survey 2009 dataset. Miscellaneous refrigeration product survey responses were weighted according to demographics of product ownership found in the general refrigeration product surveys. Model number matching for a portion of miscellaneous refrigeration product responses allowed validation of refrigeration product characteristics, which enabled more accurate estimates of the penetrations of these products in U.S. households. We estimated that there were 12.3±1.0 million wine/beverage coolers, 5.5(–3.5,+3.2) million residential icemakers and 2.9(–2.5,+4.5) million non-vapor compression refrigerators in U.S. households in 2012. (All numerical results are expressed with ranges indicating the 95% confidence interval.) No evidence was found for the existence of non-vapor compression freezers. Moreover, we found that 15% of wine/beverage coolers used vapor compression cooling technology, while 85% used thermoelectric cooling technology, with the vast majority of thermoelectric units having capacities of less than 30 wine bottles (approximately 3.5 cubic feet). No evidence was found for the existence of wine/beverage coolers with absorption cooling technology. Additionally, we estimated

Mechanical disturbances in superconducting magnets

International Nuclear Information System (INIS)

Sugimoto, Makoto

1990-03-01

The stress distribution in a small epoxy-impregnated Nb 3 Sn coil was calculated by the finite element method. Mechanical disturbances due to the electromagnetic force in the magnet are discussed. The coil stability in relation with the stress distribution is also discussed by using the experimental results. To evaluate such stresses, a calculation model was investigated. It was found that the model, which removed the internal bore element in the model magnet, gave a reasonable condition to estimate to stress. A quench mechanism due to mechanical disturbances in superconducting magnets is discussed. According to this mechanism, an internal slit was assumed as the reason for the mechanical disturbance. The internal slit is generated at the boundary between the superconductor and the bore element by the thermally induced stress. When charging a magnet, the induced electromagnetic force results in a stress concentration at the slit, and hence to an enlargement of it. During the enlargement of the internal slit, heat is generated at the top of it. Such heat generation from a mechanical disturbance can induce a quench. Through these investigations, the following coil manufacturing method can be proposed to reduce such stresses: the magnet should be manufactured to separate the bore element from the superconductor and this separation technique can reduce the boundary stress during cool-down. Actually, a thin teflon film at the boundary between the superconductor and the bore element can be used as a separator. Another separation technique is a teflon coating on the internal bore element. The separation technique should result in a stable epoxy-impregnated superconducting magnet. (J.P.N.)

CGILS: Results from the First Phase of an International Project to Understand the Physical Mechanisms of Low Cloud Feedbacks in Single Column Models

Science.gov (United States)

Zhang, Minghua; Bretherton, Christopher S.; Blossey, Peter N.; Austin, Phillip H.; Bacmeister, Julio T.; Bony, Sandrine; Brient, Florent; Cheedela, Suvarchal K.; Cheng, Anning; DelGenio, Anthony;

Pseudo-Hermitian Representation of Quantum Mechanics

International Nuclear Information System (INIS)

Mustafazade, A.

2008-01-01

I will outline a formulation of quantum mechanics in which the inner product on the Hilbert space of a quantum system is treated as a degree of freedom. I will outline some of the basic mathematical and conceptual features of the resulting theory and discuss some of its applications. In particular, I will present a quantum mechanical analogue of Einstein's field equations that links the inner product of the Hilbert space and the Hamiltonian of the system and discuss how the resulting theory can be used to address a variety of problems in classical electrodynamics, relativistic quantum mechanics, and quantum computation

Fracture mechanics in new designed power module under thermo-mechanical loads

Directory of Open Access Journals (Sweden)

Durand Camille

2014-06-01

Full Text Available Thermo-mechanically induced failure is a major reliability issue in the microelectronic industry. On this account, a new type of Assembly Interconnected Technology used to connect MOSFETs in power modules has been developed. The reliability is increased by using a copper clip soldered on the top side of the chip, avoiding the use of aluminium wire bonds, often responsible for the failure of the device. Thus the new designed MOSFET package does not follow the same failure mechanisms as standard modules. Thermal and power cycling tests were performed on these new packages and resulting failures were analyzed. Thermo-mechanical simulations including cracks in the aluminium metallization and intermetallics (IMC were performed using Finite Element Analysis in order to better understand crack propagation and module behaviour.

Research concerning the balancing of a plane mechanism

Science.gov (United States)

Bădoiu, D.; Petrescu, M. G.; Antonescu, N. N.; Toma, G.

2018-01-01

By statically balancing of the plane mechanisms and especially those functioning at high speeds is being pursued the decrease of the value of the resultant force of all inertia forces that work on the component elements, thus obtaining a significant decrease in vibrations and shocks during the functioning. On the other hand, the existence of balancing masses which ensure the balancing of the mechanism leads to increased gauge and its mass. In this paper are presented some possibilities of statically balancing a plane mechanism which is composed of three independent contours. First is analyzed the case when the mechanism is totally balanced. Then a solution is proposed for a partial balancing of the mechanism based on the balancing of the first harmonic of the inertia force developed in a piston of the mechanism. Finally, are presented some simulation results concerning the variation of the value of the resultant inertia force during a cinematic cycle when the mechanism is unbalanced and when it is partially balanced. Also, it is analyzed the variation of the motor moment when the mechanism is unbalanced and when is totally and partially balanced.

Impact Mechanics

Science.gov (United States)

Stronge, W. J.

2004-03-01

Impact mechanics is concerned with the reaction forces that develop during a collision and the dynamic response of structures to these reaction forces. The subject has a wide range of engineering applications, from designing sports equipment to improving the crashworthiness of automobiles. This book develops several different methodologies for analysing collisions between structures. These range from rigid body theory for structures that are stiff and compact, to vibration and wave analyses for flexible structures. The emphasis is on low-speed impact where damage is local to the small region of contact between the colliding bodies. The analytical methods presented give results that are more robust or less sensitive to initial conditions than have been achieved hitherto. As a text, Impact Mechanics builds upon foundation courses in dynamics and strength of materials. It includes numerous industrially relevant examples and end-of-chapter homework problems drawn from industry and sports. Practising engineers will also find the methods presented in this book useful in calculating the response of a mechanical system to impact.

Statistical ensembles in quantum mechanics

International Nuclear Information System (INIS)

Blokhintsev, D.

1976-01-01

The interpretation of quantum mechanics presented in this paper is based on the concept of quantum ensembles. This concept differs essentially from the canonical one by that the interference of the observer into the state of a microscopic system is of no greater importance than in any other field of physics. Owing to this fact, the laws established by quantum mechanics are not of less objective character than the laws governing classical statistical mechanics. The paradoxical nature of some statements of quantum mechanics which result from the interpretation of the wave functions as the observer's notebook greatly stimulated the development of the idea presented. (Auth.)

Learn new mechanisms from life

International Nuclear Information System (INIS)

Ji Qing; Luo Mingyan; Tong Xiaolin; Zhang Bo; Zhang Hui

2005-01-01

On the basis of the important experimental results of molecular motors, it was pointed out that the moving process of molecular motors is a coupling biological process of chemical-electrical-mechanical processes. This clever mechanism of energy conversion on the molecular level with several processes coupled together had never been observed before. The understanding of this new mechanism is an important step towards the understanding of life and an important content of what we can learn from life. The authors introduced here the status of the investigations on the mechanism for the force generation of kinesin and the studies of the authors in this field. (authors)

Technical diagnostics functioning machines and mechanisms

Science.gov (United States)

Kiselev, M. I.; Pronyakin, V. I.; Tulekbaeva, A. K.

2018-02-01

Article discusses the machines and mechanisms technical state monitoring problem. Approaches for estimating mechanical systems current technical state, defects detection and evaluation of mechanical elements degradation levels are considered. The paper analyzes the traditional methods offered in international and national standards, especially vibrodiagnostics. An advanced phase method is presented which is based on registration the kinematic parameters of the mechanism running cycle. The result of coupling the phase method and mathematical modeling is shown, and simulation comparison with the experimental data is presented.

Quantum Mechanics/Molecular Mechanics Study of the Sialyltransferase Reaction Mechanism.

Science.gov (United States)

Hamada, Yojiro; Kanematsu, Yusuke; Tachikawa, Masanori

2016-10-11

The sialyltransferase is an enzyme that transfers the sialic acid moiety from cytidine 5'-monophospho-N-acetyl-neuraminic acid (CMP-NeuAc) to the terminal position of glycans. To elucidate the catalytic mechanism of sialyltransferase, we explored the potential energy surface along the sialic acid transfer reaction coordinates by the hybrid quantum mechanics/molecular mechanics method on the basis of the crystal structure of sialyltransferase CstII. Our calculation demonstrated that CstII employed an S N 1-like reaction mechanism via the formation of a short-lived oxocarbenium ion intermediate. The computational barrier height was 19.5 kcal/mol, which reasonably corresponded with the experimental reaction rate. We also found that two tyrosine residues (Tyr156 and Tyr162) played a vital role in stabilizing the intermediate and the transition states by quantum mechanical interaction with CMP.

Quantum Mechanics/Molecular Mechanics Simulations Identify the Ring-Opening Mechanism of Creatininase.

Science.gov (United States)

Jitonnom, Jitrayut; Mujika, Jon I; van der Kamp, Marc W; Mulholland, Adrian J

2017-12-05

Creatininase catalyzes the conversion of creatinine (a biosensor for kidney function) to creatine via a two-step mechanism: water addition followed by ring opening. Water addition is common to other known cyclic amidohydrolases, but the precise mechanism for ring opening is still under debate. The proton donor in this step is either His178 or a water molecule bound to one of the metal ions, and the roles of His178 and Glu122 are unclear. Here, the two possible reaction pathways have been fully examined by means of combined quantum mechanics/molecular mechanics simulations at the SCC-DFTB/CHARMM22 level of theory. The results indicate that His178 is the main catalytic residue for the whole reaction and explain its role as proton shuttle during the ring-opening step. In the first step, His178 provides electrostatic stabilization to the gem-diolate tetrahedral intermediate. In the second step, His178 abstracts the hydroxyl proton of the intermediate and delivers it to the cyclic amide nitrogen, leading to ring opening. The latter is the rate-limiting step with a free energy barrier of 18.5 kcal/mol, in agreement with the experiment. We find that Glu122 must be protonated during the enzyme reaction, so that it can form a stable hydrogen bond with its neighboring water molecule. Simulations of the E122Q mutant showed that this replacement disrupts the H-bond network formed by three conserved residues (Glu34, Ser78, and Glu122) and water, increasing the energy barrier. Our computational studies provide a comprehensive explanation for previous structural and kinetic observations, including why the H178A mutation causes a complete loss of activity but the E122Q mutation does not.

Mechanics without mechanisms

Science.gov (United States)

Eisenthal, Joshua

2018-05-01

At the time of Heinrich Hertz's premature death in 1894, he was regarded as one of the leading scientists of his generation. However, the posthumous publication of his treatise in the foundations of physics, Principles of Mechanics, presents a curious historical situation. Although Hertz's book was widely praised and admired, it was also met with a general sense of dissatisfaction. Almost all of Hertz's contemporaries criticized Principles for the lack of any plausible way to construct a mechanism from the "hidden masses" that are particularly characteristic of Hertz's framework. This issue seemed especially glaring given the expectation that Hertz's work might lead to a model of the underlying workings of the ether. In this paper I seek an explanation for why Hertz seemed so unperturbed by the difficulties of constructing such a mechanism. In arriving at this explanation, I explore how the development of Hertz's image-theory of representation framed the project of Principles. The image-theory brings with it an austere view of the "essential content" of mechanics, only requiring a kind of structural isomorphism between symbolic representations and target phenomena. I argue that bringing this into view makes clear why Hertz felt no need to work out the kinds of mechanisms that many of his readers looked for. Furthermore, I argue that a crucial role of Hertz's hypothesis of hidden masses has been widely overlooked. Far from acting as a proposal for the underlying structure of the ether, I show that Hertz's hypothesis ruled out knowledge of such underlying structure.

MECHANICAL AND THERMO–MECHANICAL PROPERTIES OF BI-DIRECTIONAL AND SHORT CARBON FIBER REINFORCED EPOXY COMPOSITES

Directory of Open Access Journals (Sweden)

G. AGARWAL

2014-10-01

Full Text Available This paper based on bidirectional and short carbon fiber reinforced epoxy composites reports the effect of fiber loading on physical, mechanical and thermo-mechanical properties respectively. The five different fiber loading, i.e., 10wt. %, 20wt. %, 30wt. %, 40wt. % and 50wt. % were taken for evaluating the above said properties. The physical and mechanical properties, i.e., hardness, tensile strength, flexural strength, inter-laminar shear strength and impact strength are determined to represent the behaviour of composite structures with that of fiber loading. Thermo-mechanical properties of the material are measured with the help of Dynamic Mechanical Analyser to measure the damping capacity of the material that is used to reduce the vibrations. The effect of storage modulus, loss modulus and tan delta with temperature are determined. Finally, Cole–Cole analysis is performed on both bidirectional and short carbon fiber reinforced epoxy composites to distinguish the material properties of either homogeneous or heterogeneous materials. The results show that with the increase in fiber loading the mechanical properties of bidirectional carbon fiber reinforced epoxy composites increases as compared to short carbon fiber reinforced epoxy composites except in case of hardness, short carbon fiber reinforced composites shows better results. Similarly, as far as Loss modulus, storage modulus is concerned bidirectional carbon fiber shows better damping behaviour than short carbon fiber reinforced composites.

Axiomatic electrodynamics and microscopic mechanics

International Nuclear Information System (INIS)

Yussouff, M.

1981-04-01

A new approach to theoretical physics, along with the basic formulation of a new MICROSCOPIC MECHANICS for the motion of small charged particles is described in this set of lecture notes. Starting with the classical (Newtonian) mechanics and classical fields, the important but well known properties of Classical Electromagnetic field are discussed up to section 4. The next nection describes the usual radiation damping theory and its difficulties. It is argued that the usual treatment of radiation damping is not valid for small space and time intervals and the true description of motion requires a new type of mechanics - the MICROSCOPIC MECHANICS: Section 6 and 7 are devoted to showing that not only the new microscopic mechanics goes over to Newtonian mechanics in the proper limit, but also it is closely connected with Quantum Mechanics. All the known results of the Schroedinger theory can be reproduced by microscopic mechanics which also gives a clear physical picture. It removes Einstein's famous objections against Quantum Theory and provides a clear distinction between classical and Quantum behavior. Seven Axioms (three on Classical Mechanics, two for Maxwell's theory, one for Relativity and a new Axiom on Radiation damping) are shown to combine Classical Mechanics, Maxwellian Electrodynamics, Relativity and Schroedinger's Quantum Theory within a single theoretical framework under Microscopic Mechanics which awaits further development at the present time. (orig.)

Mechanical generation of spin current

Directory of Open Access Journals (Sweden)

Mamoru eMatsuo

2015-07-01

Full Text Available We focus the recent results on spin-current generation from mechanical motion such as rigid rotation and elastic deformations. Spin transport theory in accelerating frames is constructed by using the low energy expansion of the generally covariant Dirac equation. Related issues on spin-manipulation by mechanical rotation are also discussed.

Failure mechanism dependence and reliability evaluation of non-repairable system

International Nuclear Information System (INIS)

Chen, Ying; Yang, Liu; Ye, Cui; Kang, Rui

2015-01-01

Reliability study of electronic system with the physics-of-failure method has been promoted due to the increase knowledge of electronic failure mechanisms. System failure initiates from independent failure mechanisms, have effect on or affect by other failure mechanisms and finally result in system failure. Failure mechanisms in a non-repairable system have many kinds of correlation. One failure mechanism developing to a certain degree will trigger, accelerate or inhibit another or many other failure mechanisms, some kind of failure mechanisms may have the same effect on the failure site, component or system. The destructive effect will be accumulated and result in early failure. This paper presents a reliability evaluation method considering correlativity among failure mechanisms, which includes trigger, acceleration, inhibition, accumulation, and competition. Based on fundamental rule of physics of failure, decoupling methods of these correlations are discussed. With a case, reliability of electronic system is evaluated considering failure mechanism dependence. - Highlights: • Five types of failure mechanism correlations are described. • Decoupling methods of these correlations are discussed. • A reliability evaluation method considering mechanism dependence is proposed. • Results are quite different to results under failure independence assumption

Results From an International Simulation Study on Coupled Thermal, Hydrological, and Mechanical (THM) Processes Near Geological Nuclear Waste Repositories

International Nuclear Information System (INIS)

J. Rutqvist; D. Barr; J.T. Birkholzer; M. Chijimatsu; O. Kolditz; Q. Liu; Y. Oda; W. Wang; C. Zhang

2006-01-01

As part of the ongoing international DECOVALEX project, four research teams used five different models to simulate coupled thermal, hydrological, and mechanical (THM) processes near waste emplacement drifts of geological nuclear waste repositories. The simulations were conducted for two generic repository types, one with open and the other with back-filled repository drifts, under higher and lower postclosure temperatures, respectively. In the completed first model inception phase of the project, a good agreement was achieved between the research teams in calculating THM responses for both repository types, although some disagreement in hydrological responses is currently being resolved. In particular, good agreement in the basic thermal-mechanical responses was achieved for both repository types, even though some teams used relatively simplified thermal-elastic heat-conduction models that neglected complex near-field thermal-hydrological processes. The good agreement between the complex and simplified process models indicates that the basic thermal-mechanical responses can be predicted with a relatively high confidence level

New mechanism of spiral wave initiation in a reaction-diffusion-mechanics system.

Science.gov (United States)

Weise, Louis D; Panfilov, Alexander V

2011-01-01

Spiral wave initiation in the heart muscle is a mechanism for the onset of dangerous cardiac arrhythmias. A standard protocol for spiral wave initiation is the application of a stimulus in the refractory tail of a propagating excitation wave, a region that we call the "classical vulnerable zone." Previous studies of vulnerability to spiral wave initiation did not take the influence of deformation into account, which has been shown to have a substantial effect on the excitation process of cardiomyocytes via the mechano-electrical feedback phenomenon. In this work we study the effect of deformation on the vulnerability of excitable media in a discrete reaction-diffusion-mechanics (dRDM) model. The dRDM model combines FitzHugh-Nagumo type equations for cardiac excitation with a discrete mechanical description of a finite-elastic isotropic material (Seth material) to model cardiac excitation-contraction coupling and stretch activated depolarizing current. We show that deformation alters the "classical," and forms a new vulnerable zone at longer coupling intervals. This mechanically caused vulnerable zone results in a new mechanism of spiral wave initiation, where unidirectional conduction block and rotation directions of the consequently initiated spiral waves are opposite compared to the mechanism of spiral wave initiation due to the "classical vulnerable zone." We show that this new mechanism of spiral wave initiation can naturally occur in situations that involve wave fronts with curvature, and discuss its relation to supernormal excitability of cardiac tissue. The concept of mechanically induced vulnerability may lead to a better understanding about the onset of dangerous heart arrhythmias via mechano-electrical feedback.

Simulation with quantum mechanics/molecular mechanics for drug discovery.

Science.gov (United States)

Barbault, Florent; Maurel, François

2015-10-01

Biological macromolecules, such as proteins or nucleic acids, are (still) molecules and thus they follow the same chemical rules that any simple molecule follows, even if their size generally renders accurate studies unhelpful. However, in the context of drug discovery, a detailed analysis of ligand association is required for understanding or predicting their interactions and hybrid quantum mechanics/molecular mechanics (QM/MM) computations are relevant tools to help elucidate this process. In this review, the authors explore the use of QM/MM for drug discovery. After a brief description of the molecular mechanics (MM) technique, the authors describe the subtractive and additive techniques for QM/MM computations. The authors then present several application cases in topics involved in drug discovery. QM/MM have been widely employed during the last decades to study chemical processes such as enzyme-inhibitor interactions. However, despite the enthusiasm around this area, plain MM simulations may be more meaningful than QM/MM. To obtain reliable results, the authors suggest fixing several keystone parameters according to the underlying chemistry of each studied system.

Assessment of the mechanical stability of underground excavations

International Nuclear Information System (INIS)

Kuroki, Shigemori; Taniguchi, Wataru

1999-01-01

Each tunnel in the underground high level radioactive waste repository must be mechanically stable to maintain safety throughout the construction, emplacement operations and closure phase. The mechanical stability of underground excavations were assessed using a theoretical analysis and a finite element method taking a wide range of geological environment in Japan into consideration to establish confidence in the construction of disposal facilities. The results show that it is possible to maintain the mechanical stability with adequate tunnel spacing and disposal pit pitch and proper mechanical support. The procedure used for the analysis of the mechanical stability in the H12 report and the results are described in this report. (author)

Mechanical tunnel excavation in welded tuff

International Nuclear Information System (INIS)

Sperry, P.E.

1991-01-01

The Technical Review Board for the US high-level radioactive waste facility at Yucca Mountain has recommended maximum use of open-quotes the most modern mechanical excavation techniques...in order to reduce disturbance to the rock walls and to achieve greater economy of time and cost.close quotes Tunnels for the waste repository at Yucca Mountain can be economically constructed with mechanical excavation equipment. This paper presents the results of mechanical excavation of a tunnel in welded tuff, similar to the tuffs of Yucca Mountain. These results are projected to excavation of emplacement drifts in Yucca Mountain using a current state-of-the-art tunnel boring machine (TBM)

Unusual cause of mechanical ileus

Energy Technology Data Exchange (ETDEWEB)

Strobel, E S; Beck, A H

1987-07-01

A patient with the signs of mechanic ileus is reported. Past history of dilative cardiomyopathy with atrial fibrillation and the recent occlusion of the left renal artery suggested arterial mesenteric embolism. Celiacography ruled out mesenteric thromboembolism and vigorous enemas resulted in the delivery of the foreign bodies causing the mechanic ileus: 2 '10-Pfennig' coins.

Mechanism of charity activity

Directory of Open Access Journals (Sweden)

Roman B. Golovkin

2015-12-01

Full Text Available Objective to establish the essential properties of the mechanism of charitable activities and to formulate the concept of quotmechanism of charitable activityquot. Methods the objective of the study is achieved using the complex of methods which are based on the interaction of dialectical and metaphysical analysis the epistemological properties of which allowed to reveal various aspects of the charitable activities mechanism functioning taking into account the principles of comprehensiveness complexity specificity and objectivity of the research. Results the rules are stated of using the term quotmechanismquot to characterize actions of state and law the essence of the charity mechanism is defined the definition of quotthe mechanism of charitable activity quot is formulated. Scientific novelty for the first time at theoretical level in legal science the definition of quotthe mechanism of charitable activityquot is formulated and its essential properties are set. Practical significance the research will contribute to improving the legal regulation in the field of philanthropy as well as to improving the efficiency and quality of charitable activity in the Russian Federation. nbsp

Nonlinear crack mechanics

International Nuclear Information System (INIS)

Khoroshun, L.P.

1995-01-01

The characteristic features of the deformation and failure of actual materials in the vicinity of a crack tip are due to their physical nonlinearity in the stress-concentration zone, which is a result of plasticity, microfailure, or a nonlinear dependence of the interatomic forces on the distance. Therefore, adequate models of the failure mechanics must be nonlinear, in principle, although linear failure mechanics is applicable if the zone of nonlinear deformation is small in comparison with the crack length. Models of crack mechanics are based on analytical solutions of the problem of the stress-strain state in the vicinity of the crack. On account of the complexity of the problem, nonlinear models are bason on approximate schematic solutions. In the Leonov-Panasyuk-Dugdale nonlinear model, one of the best known, the actual two-dimensional plastic zone (the nonlinearity zone) is replaced by a narrow one-dimensional zone, which is then modeled by extending the crack with a specified normal load equal to the yield point. The condition of finite stress is applied here, and hence the length of the plastic zone is determined. As a result of this approximation, the displacement in the plastic zone at the abscissa is nonzero

Control-rod driving mechanism

International Nuclear Information System (INIS)

Jodoi, Takashi.

1976-01-01

Purpose: To prevent falling of control rods due to malfunction. Constitution: The device of the present invention has a scram function in particular, and uses principally a fluid pressure as a scram accelerating means. The control rod is held by upper and lower holding devices, which are connected by a connecting mechanism. This connecting mechanism is designed to be detachable only at the lower limit of driving stroke of the control rod so that there occurs no erroneous scram resulting from careless disconnection of the connecting mechanism. Further, scramming operation due to own weight of the scram operating portion such as control rod driving shaft may be effected to increase freedom. (Kamimura, M.)

Quantum mechanics and its limits

International Nuclear Information System (INIS)

Lamehi-Rachti, M.; Mittig, W.

1977-01-01

Bell has shown (Bell's inequality) that local hidden variable theories lead to predictions in contradiction with quantum mechanics. This has been tested in low energy proton-proton scattering by the simultaneous measurement of the polarisation of the two protons. The results are in agreement with quantum mechanics and thus in contradiction with the inequality of Bell [fr

Analysis of kinetic reaction mechanisms

CERN Document Server

Turányi, Tamás

2014-01-01

Chemical processes in many fields of science and technology, including combustion, atmospheric chemistry, environmental modelling, process engineering, and systems biology, can be described by detailed reaction mechanisms consisting of numerous reaction steps. This book describes methods for the analysis of reaction mechanisms that are applicable in all these fields. Topics addressed include: how sensitivity and uncertainty analyses allow the calculation of the overall uncertainty of simulation results and the identification of the most important input parameters, the ways in which mechanisms can be reduced without losing important kinetic and dynamic detail, and the application of reduced models for more accurate engineering optimizations. This monograph is invaluable for researchers and engineers dealing with detailed reaction mechanisms, but is also useful for graduate students of related courses in chemistry, mechanical engineering, energy and environmental science and biology.

Investigation of Nonholonomic Mechanics, Vakonomic Mechanics ...

African Journals Online (AJOL)

In this article, methods of modeling dynamic systems namely, Nonholonomic mechanics, Vakonomic mechanics and Chetaev methods for constrained dynamic system are investigated. The fact that Vakonomic mechanics gives a different motion equation to the other methods is verified using a particular example. It is shown ...

Effect of Mechanical Alloying Atmospheres and Oxygen Concentration on Mechanical Properties of ODS Ferritic Steels

International Nuclear Information System (INIS)

Noh, Sanghoon; Choi, Byoungkwon; Han, Changhee; Kim, Kibaik; Kang, Sukhoon; Chun, Youngbum; Kim, Taekyu

2013-01-01

Finely dispersed nano-oxide particles with a high number density in the homogeneous grain matrix are essential to achieve superior mechanical properties at high temperatures, and these unique microstructures can be obtained through the mechanical alloying (MA) and hot consolidation process. The microstructure and mechanical property of ODS steel significantly depends on its powder property and the purity after the MA process. These contents should be carefully controlled to improve the mechanical property at elevated temperature. In particular, appropriate the control of oxygen concentration improves the mechanical property of ODS steel at high temperature. An effective method is to control the mechanical alloying atmosphere by high purity inert gas. In the present study, the effects of mechanical alloying atmospheres and oxygen concentration on the mechanical property of ODS steel were investigated. ODS ferritic alloys were fabricated in various atmospheres, and the HIP process was used to investigate the effects of MA atmospheres and oxygen concentration on the microstructure and mechanical property. ODS ferritic alloys milled in an Ar-H 2 mixture, and He is effective to reduce the excess oxygen concentration. The YH 2 addition made an extremely reduced oxygen concentration by the internal oxygen reduction reaction and resulted in a homogeneous microstructure and superior creep strength

New mechanism of spiral wave initiation in a reaction-diffusion-mechanics system.

Directory of Open Access Journals (Sweden)

Louis D Weise

Full Text Available Spiral wave initiation in the heart muscle is a mechanism for the onset of dangerous cardiac arrhythmias. A standard protocol for spiral wave initiation is the application of a stimulus in the refractory tail of a propagating excitation wave, a region that we call the "classical vulnerable zone." Previous studies of vulnerability to spiral wave initiation did not take the influence of deformation into account, which has been shown to have a substantial effect on the excitation process of cardiomyocytes via the mechano-electrical feedback phenomenon. In this work we study the effect of deformation on the vulnerability of excitable media in a discrete reaction-diffusion-mechanics (dRDM model. The dRDM model combines FitzHugh-Nagumo type equations for cardiac excitation with a discrete mechanical description of a finite-elastic isotropic material (Seth material to model cardiac excitation-contraction coupling and stretch activated depolarizing current. We show that deformation alters the "classical," and forms a new vulnerable zone at longer coupling intervals. This mechanically caused vulnerable zone results in a new mechanism of spiral wave initiation, where unidirectional conduction block and rotation directions of the consequently initiated spiral waves are opposite compared to the mechanism of spiral wave initiation due to the "classical vulnerable zone." We show that this new mechanism of spiral wave initiation can naturally occur in situations that involve wave fronts with curvature, and discuss its relation to supernormal excitability of cardiac tissue. The concept of mechanically induced vulnerability may lead to a better understanding about the onset of dangerous heart arrhythmias via mechano-electrical feedback.

Predictable 'meta-mechanisms' emerge from feedbacks between transpiration and plant growth and cannot be simply deduced from short-term mechanisms.

Science.gov (United States)

Tardieu, François; Parent, Boris

2017-06-01

Growth under water deficit is controlled by short-term mechanisms but, because of numerous feedbacks, the combination of these mechanisms over time often results in outputs that cannot be deduced from the simple inspection of individual mechanisms. It can be analysed with dynamic models in which causal relationships between variables are considered at each time-step, allowing calculation of outputs that are routed back to inputs for the next time-step and that can change the system itself. We first review physiological mechanisms involved in seven feedbacks of transpiration on plant growth, involving changes in tissue hydraulic conductance, stomatal conductance, plant architecture and underlying factors such as hormones or aquaporins. The combination of these mechanisms over time can result in non-straightforward conclusions as shown by examples of simulation outputs: 'over production of abscisic acid (ABA) can cause a lower concentration of ABA in the xylem sap ', 'decreasing root hydraulic conductance when evaporative demand is maximum can improve plant performance' and 'rapid root growth can decrease yield'. Systems of equations simulating feedbacks over numerous time-steps result in logical and reproducible emergent properties that can be viewed as 'meta-mechanisms' at plant level, which have similar roles as mechanisms at cell level. © 2016 John Wiley & Sons Ltd.

Clinical Results and Mechanical Properties of the Carotid CGUARD Double-Layered Embolic Prevention Stent.

Science.gov (United States)

Wissgott, Christian; Schmidt, Wolfram; Brandt-Wunderlich, Christoph; Behrens, Peter; Andresen, Reimer

2017-02-01

To report early clinical outcomes with a novel double-layer stent for the internal carotid artery (ICA) and the in vitro investigation of the stent's mechanical properties. A prospective single-center study enrolled 30 consecutive patients (mean age 73.1±6.3 years; 21 men) with symptomatic (n=25) or high-grade (n=5) ICA stenosis treated with the new double-layer carotid CGUARD Embolic Prevention System (EPS) stent, which has an inner open-cell nitinol design with an outer closed-cell polyethylene terephthalate layer. The average stenosis of the treated arteries was 84.1%±7.9% with a mean lesion length of 16.6±2.1 mm. In the laboratory, 8×40-mm stents where tested in vitro with respect to their radial force during expansion, the bending stiffness of the stent system and the expanded stent, as well as the collapse pressure in a thin and flexible sheath. The wall adaptation was assessed using fluoroscopy after stent release in step and curved vessel models. The stent was successfully implanted in all patients. No peri- or postprocedural complications occurred; no minor or major stroke was observed in the 6-month follow-up. The bending stiffness of the expanded stent was 63.1 N·mm 2 and (not unexpectedly) was clearly lower than that of the stent system (601.5 N·mm 2 ). The normalized radial force during expansion of the stent to 7.0 mm, consistent with in vivo sizing, was relatively high (0.056 N/mm), which correlates well with the collapse pressure of 0.17 bars. Vessel wall adaptation was harmonic and caused no straightening of the vessel after clinical application. Because of its structure, the novel CGUARD EPS stent is characterized by a high flexibility combined with a high radial force and very good plaque coverage. These first clinical results demonstrate a very safe implantation behavior without any stroke up to 6 months after the procedure.

The Effect of the Loading on Dynamic Stability and Scapular Asymmetry

Directory of Open Access Journals (Sweden)

Mohammad Hassan Azarsa

2014-03-01

Full Text Available Background: Scapular stabilization and neuromuscular control provide an important parameter to characterize shoulder function during dynamic activities. Many studies have confirmed the effect of the loading on scapular position and scapulohumeral rhythm. Therefore, the evaluation of stabilizer muscles involvement in scapular asymmetry may assist in the development of clinical examination and rehabilitation program. The aim of this study was to evaluate the effect of loading on dynamic stability and scapular asymmetry in basketball players. Methods: Thirty healthy male basketball players aged between 20 to 31 years old were tested. The linear distance between scapular inferior angle and T7 spinous process was measured using a caliper in 90 degrees of unloaded scaption and with 1, 2 and 4 kg loading. The difference of distances of two sides in the above 4 positions was analyzed. Results: The amount of distances difference in two sides with 1 kg loading was minimal (9.36 mm. This difference increased to 10.19 mm and 12.22 mm, with increasing the loading to 2 and 4 kg respectively; although the 4 positions of the test did not show significant differences in distances difference (P>0.05. Conclusion: This study shows that dynamic stability of the scapula is dependent on the role of muscles, so that with increasing load on the muscles, the scapular asymmetry is more pronounced.

Noncanonical Hamiltonian mechanics

International Nuclear Information System (INIS)

Litteljohn, R.G.

1986-01-01

Noncanonical variables in Hamiltonian mechanics were first used by Lagrange in 1808. In spite of this, most work in Hamiltonian mechanics has been carried out in canonical variables, up to this day. One reason for this is that noncanonical coordinates are seldom needed for mechanical problems based on Lagrangians of the form L = T - V, where T is the kinetic energy and V is the potential energy. Of course, such Lagrangians arise naturally in celestial mechanics, and as a result they form the paradigms of nineteenth-century mechanics and have become enshrined in all the mechanics textbooks. Certain features of modern problems, however, lead to the use of noncanonical coordinates. Among these are issues of gauge invariance and singular Lagrange a Poisson structures. In addition, certain problems, like the flow of magnetic-field lines in physical space, are naturally formulated in terms of noncanonical coordinates. None of these features is present in the nineteenth-century paradigms of mechanics, but they do arise in problems involving particle motion in the presence of magnetic fields. For example, the motion of a particle in an electromagnetic wave is an important one in plasma physics, but the usual Hamiltonian formulation is gauge dependent. For this problem, noncanonical approaches based on Lagrangians in phase space lead to powerful computational techniques which are gauge invariant. In the limit of strong magnetic fields, particle motion becomes 'guiding-center motion'. Guiding-center motion is also best understood in terms of noncanonical coordinates. Finally the flow of magnetic-field lines through physical space is a Hamiltonian system which is best understood with noncanonical coordinates. No doubt many more systems will arise in the future for which these noncanonical techniques can be applied. (author)

Modeling the mechanics of cancer: effect of changes in cellular and extra-cellular mechanical properties.

Science.gov (United States)

Katira, Parag; Bonnecaze, Roger T; Zaman, Muhammad H

2013-01-01

Malignant transformation, though primarily driven by genetic mutations in cells, is also accompanied by specific changes in cellular and extra-cellular mechanical properties such as stiffness and adhesivity. As the transformed cells grow into tumors, they interact with their surroundings via physical contacts and the application of forces. These forces can lead to changes in the mechanical regulation of cell fate based on the mechanical properties of the cells and their surrounding environment. A comprehensive understanding of cancer progression requires the study of how specific changes in mechanical properties influences collective cell behavior during tumor growth and metastasis. Here we review some key results from computational models describing the effect of changes in cellular and extra-cellular mechanical properties and identify mechanistic pathways for cancer progression that can be targeted for the prediction, treatment, and prevention of cancer.

Fracture Mechanics

International Nuclear Information System (INIS)

Jang, Dong Il; Jeong, Gyeong Seop; Han, Min Gu

1992-08-01

This book introduces basic theory and analytical solution of fracture mechanics, linear fracture mechanics, non-linear fracture mechanics, dynamic fracture mechanics, environmental fracture and fatigue fracture, application on design fracture mechanics, application on analysis of structural safety, engineering approach method on fracture mechanics, stochastic fracture mechanics, numerical analysis code and fracture toughness test and fracture toughness data. It gives descriptions of fracture mechanics to theory and analysis from application of engineering.

Common Mechanisms Underlying Refractive Error Identified in Functional Analysis of Gene Lists From Genome-Wide Association Study Results in 2 European British Cohorts

Science.gov (United States)

Hysi, Pirro G.; Mahroo, Omar A.; Cumberland, Phillippa; Wojciechowski, Robert; Williams, Katie M.; Young, Terri L.; Mackey, David A.; Rahi, Jugnoo S.; Hammond, Christopher J.

2014-01-01

IMPORTANCE To date, relatively few genes responsible for a fraction of heritability have been identified by means of large genetic association studies of refractive error. OBJECTIVE To explore the genetic mechanisms that lead to refractive error in the general population. DESIGN, SETTING, AND PARTICIPANTS Genome-wide association studies were carried out in 2 British population-based independent cohorts (N = 5928 participants) to identify genes moderately associated with refractive error. MAIN OUTCOMES AND MEASURES Enrichment analyses were used to identify sets of genes overrepresented in both cohorts. Enriched groups of genes were compared between both participating cohorts as a further measure against random noise. RESULTS Groups of genes enriched at highly significant statistical levels were remarkably consistent in both cohorts. In particular, these results indicated that plasma membrane (P = 7.64 × 10−30), cell-cell adhesion (P = 2.42 × 10−18), synaptic transmission (P = 2.70 × 10−14), calcium ion binding (P = 3.55 × 10−15), and cation channel activity (P = 2.77 × 10−14) were significantly overrepresented in relation to refractive error. CONCLUSIONS AND RELEVANCE These findings provide evidence that development of refractive error in the general population is related to the intensity of photosignal transduced from the retina, which may have implications for future interventions to minimize this disorder. Pathways connected to the procession of the nerve impulse are major mechanisms involved in the development of refractive error in populations of European origin. PMID:24264139

Comparative spring mechanics in mantis shrimp.

Science.gov (United States)

Patek, S N; Rosario, M V; Taylor, J R A

2013-04-01

Elastic mechanisms are fundamental to fast and efficient movements. Mantis shrimp power their fast raptorial appendages using a conserved network of exoskeletal springs, linkages and latches. Their appendages are fantastically diverse, ranging from spears to hammers. We measured the spring mechanics of 12 mantis shrimp species from five different families exhibiting hammer-shaped, spear-shaped and undifferentiated appendages. Across species, spring force and work increase with size of the appendage and spring constant is not correlated with size. Species that hammer their prey exhibit significantly greater spring resilience compared with species that impale evasive prey ('spearers'); mixed statistical results show that species that hammer prey also produce greater work relative to size during spring loading compared with spearers. Disabling part of the spring mechanism, the 'saddle', significantly decreases spring force and work in three smasher species; cross-species analyses show a greater effect of cutting the saddle on the spring force and spring constant in species without hammers compared with species with hammers. Overall, the study shows a more potent spring mechanism in the faster and more powerful hammering species compared with spearing species while also highlighting the challenges of reconciling within-species and cross-species mechanical analyses when different processes may be acting at these two different levels of analysis. The observed mechanical variation in spring mechanics provides insights into the evolutionary history, morphological components and mechanical behavior, which were not discernible in prior single-species studies. The results also suggest that, even with a conserved spring mechanism, spring behavior, potency and component structures can be varied within a clade with implications for the behavioral functions of power-amplified devices.

The Mechanics of Mechanical Watches and Clocks

CERN Document Server

Du, Ruxu

2013-01-01

"The Mechanics of Mechanical Watches and Clocks" presents historical views and mathematical models of mechanical watches and clocks. Although now over six hundred years old, mechanical watches and clocks are still popular luxury items that fascinate many people around the world. However few have examined the theory of how they work as presented in this book. The illustrations and computer animations are unique and have never been published before. It will be of significant interest to researchers in mechanical engineering, watchmakers and clockmakers, as well as people who have an engineering background and are interested in mechanical watches and clocks. It will also inspire people in other fields of science and technology, such as mechanical engineering and electronics engineering, to advance their designs. Professor Ruxu Du works at the Chinese University of Hong Kong, China. Assistant Professor Longhan Xie works at the South China University of Technology, China.

On the question of determining the amount of experiments, reliability and accuracy of the results in the study of physical-mechanical properties of rocks

Directory of Open Access Journals (Sweden)

Kuznetcov n.n.

2015-06-01

Full Text Available A comparative analysis of the methods for determining the required amount of experiments, the accuracy and reliability of the results of physical-mechanical rock properties study has been conducted. The advantages and disadvantages of the existing specialized method for determining the compressive strength of the samples have been discussed. On the basis of the investigation the optimal approach has been proposed to solve a wide range of the problems associated with the rock properties' parameters using

Optimisation Methods for Cam Mechanisms

Directory of Open Access Journals (Sweden)

Claudia–Mari Popa

2010-01-01

Full Text Available In this paper we present the criteria which represent the base of optimizing the cam mechanisms and also we perform the calculations for several types of mechanisms. We study the influence of the constructive parameters in case of the simple machines with rotation cam and follower (flat or curve of translation on the curvature radius and that of the transmission angle. As it follows, we present the optimization calculations of the cam and flat rotation follower mechanisms, as well as the calculations for optimizing the cam mechanisms by circular groove followers’ help. For an easier interpretation of the results, we have visualized the obtained cam in AutoCAD according to the script files generated by a calculation program.

Computing pKa Values with a Mixing Hamiltonian Quantum Mechanical/Molecular Mechanical Approach.

Science.gov (United States)

Liu, Yang; Fan, Xiaoli; Jin, Yingdi; Hu, Xiangqian; Hu, Hao

2013-09-10

Accurate computation of the pKa value of a compound in solution is important but challenging. Here, a new mixing quantum mechanical/molecular mechanical (QM/MM) Hamiltonian method is developed to simulate the free-energy change associated with the protonation/deprotonation processes in solution. The mixing Hamiltonian method is designed for efficient quantum mechanical free-energy simulations by alchemically varying the nuclear potential, i.e., the nuclear charge of the transforming nucleus. In pKa calculation, the charge on the proton is varied in fraction between 0 and 1, corresponding to the fully deprotonated and protonated states, respectively. Inspired by the mixing potential QM/MM free energy simulation method developed previously [H. Hu and W. T. Yang, J. Chem. Phys. 2005, 123, 041102], this method succeeds many advantages of a large class of λ-coupled free-energy simulation methods and the linear combination of atomic potential approach. Theory and technique details of this method, along with the calculation results of the pKa of methanol and methanethiol molecules in aqueous solution, are reported. The results show satisfactory agreement with the experimental data.

The formation mechanism of mechanically alloyed Fe-20 at% Al powder

Energy Technology Data Exchange (ETDEWEB)

Hadef, F., E-mail: hadef77@yahoo.fr [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Universite 20 Aout 1955, BP 26, Route d' El-Hadaiek, Skikda 21000 (Algeria); Otmani, A. [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Universite 20 Aout 1955, BP 26, Route d' El-Hadaiek, Skikda 21000 (Algeria); Djekoun, A. [Laboratoire de Magnetisme et Spectroscopie des Solides, LM2S, Universite Badji Mokhtar, BP 12 Annaba 23000 (Algeria); Greneche, J.M. [LUNAM, Universite du Maine, Institut des Molecules et Materiaux du Mans, UMR CNRS 6283, 72085 Le Mans (France)

2013-01-15

The formation mechanism of the mechanically alloyed Fe-20 at% Al, from elemental Fe and Al powders, has been investigated. The experimental results indicate the formation of a nanocrystalline bcc {alpha}-Fe(Al) solid solution with a lattice parameter close to a{sub {alpha}-Fe(Al)}=0.2890 nm, where each Fe atom is surrounded by (6Fe+2Al) in the first coordination sphere. The reaction mechanism of MA process seems to be controlled by a diffusion phenomenon. Aluminum particles undergo an important refinement to the nanometer scale and then they stick on Fe particles of large sizes. A large number of clear Al/Fe interface areas were generated. The short diffusion path and the presence of high concentration of defects accelerated the solid state reaction. - Highlights: Black-Right-Pointing-Pointer A nanocrystalline bcc {alpha}-Fe(Al) solid solution is formed from elemental Fe and Al powders. Black-Right-Pointing-Pointer The reaction mechanism of MA process seems to be controlled by a diffusion phenomenon. Black-Right-Pointing-Pointer Each Fe atom is surrounded by (6Fe+2Al) in the first coordination sphere.

S-equivalents lagrangians in generalized mechanics

International Nuclear Information System (INIS)

Negri, L.J.; Silva, Edna G. da.

1985-01-01

The problem of s-equivalent lagrangians is considered in the realm of generalized mechanics. Some results corresponding to the ordinary (non-generalized) mechanics are extended to the generalized case. A theorem for the reduction of the higher order lagrangian description to the usual order is found to be useful for the analysis of generalized mechanical systems and leads to a new class of equivalence between lagrangian functions. Some new perspectives are pointed out. (Author) [pt

Clinical challenges in mechanical ventilation.

Science.gov (United States)

Goligher, Ewan C; Ferguson, Niall D; Brochard, Laurent J

2016-04-30

Mechanical ventilation supports gas exchange and alleviates the work of breathing when the respiratory muscles are overwhelmed by an acute pulmonary or systemic insult. Although mechanical ventilation is not generally considered a treatment for acute respiratory failure per se, ventilator management warrants close attention because inappropriate ventilation can result in injury to the lungs or respiratory muscles and worsen morbidity and mortality. Key clinical challenges include averting intubation in patients with respiratory failure with non-invasive techniques for respiratory support; delivering lung-protective ventilation to prevent ventilator-induced lung injury; maintaining adequate gas exchange in severely hypoxaemic patients; avoiding the development of ventilator-induced diaphragm dysfunction; and diagnosing and treating the many pathophysiological mechanisms that impair liberation from mechanical ventilation. Personalisation of mechanical ventilation based on individual physiological characteristics and responses to therapy can further improve outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

One-to-one correspondence of charge-imbalance relaxing mechanisms with pair-breaking mechanisms in superconductors

International Nuclear Information System (INIS)

Lemberger, T.R.

1984-01-01

A one-to-one correspondence of charge-imbalance relaxing mechanisms with pair-breaking mechanisms in superconductors is demonstrated. The characteristic rates for these two effects are shown to be equal, within factors of order unity. These results are used to estimate the charge-imbalance relaxation rate associated with the proximity effect of a normal metal in metallic contact with a superconductor

Mechanical properties of fracture zones

International Nuclear Information System (INIS)

Leijon, B.

1993-05-01

Available data on mechanical characteristics of fracture zones are compiled and discussed. The aim is to improve the basis for adequate representation of fracture zones in geomechanical models. The sources of data researched are primarily borehole investigations and case studies in rock engineering, involving observations of fracture zones subjected to artificial load change. Boreholes only yield local information about the components of fracture zones, i.e. intact rock, fractures and various low-strength materials. Difficulties are therefore encountered in evaluating morphological and mechanical properties of fracture zones from borehole data. Although often thought of as macroscopically planar features, available field data consistently show that fracture zones are characterized by geometrical irregularities such as thickness variations, surface undulation and jogs. These irregularities prevail on all scales. As a result, fracture zones are on all scales characterized by large, in-plane variation of strength- and deformational properties. This has important mechanical consequences in terms of non-uniform stress transfer and complex mechanisms of shear deformation. Field evidence for these findings, in particular results from the underground research laboratory in Canada and from studies of induced fault slip in deep mines, is summarized and discussed. 79 refs

Wave forming mechanisms in explosive welding

NARCIS (Netherlands)

Carton, E.P.

2004-01-01

Experimental results of wavy metal interfaces obtained by explosive welding are presented and used to determine which wave forming mechanism occurred. It was found that for small collision angles (smaller than about 20°) the Von Karman or jet indentation mechanism occurs, while for large collision

The dynamics of the H(+) + D(2) reaction: a comparison of quantum mechanical wavepacket, quasi-classical and statistical-quasi-classical results.

Science.gov (United States)

Jambrina, P G; Aoiz, F J; Bulut, N; Smith, Sean C; Balint-Kurti, G G; Hankel, M

2010-02-07

A detailed study of the proton exchange reaction H(+) + D(2)(v = 0, j = 0) --> HD + D(+) on its ground 1(1)A' potential energy surface has been carried out using 'exact' close-coupled quantum mechanical wavepacket (WP-EQM), quasi-classical trajectory (QCT), and statistical quasi-classical trajectory (SQCT) calculations for a range of collision energies starting from the reaction threshold to 1.3 eV. The WP-EQM calculations include all total angular momenta up to J(max) = 50, and therefore the various dynamical observables are converged up to 0.6 eV. It has been found that it is necessary to include all Coriolis couplings to obtain reliable converged results. Reaction probabilities obtained using the different methods are thoroughly compared as a function of the total energy for a series of J values. Comparisons are also made of total reaction cross sections as function of the collision energy, and rate constants. In addition, opacity functions, integral cross sections (ICS) and differential cross sections (DCS) are presented at 102 meV, 201.3 meV and 524.6 meV collision energy. The agreement between the three sets of results is only qualitative. The QCT calculations fail to describe the overall reactivity and most of the dynamical observables correctly. At low collision energies, the QCT method is plagued by the lack of conservation of zero point energy, whilst at higher collision energies and/or total angular momenta, the appearance of an effective repulsive potential associated with the centrifugal motion "over" the well causes a substantial decrease of the reactivity. In turn, the statistical models overestimate the reactivity over the whole range of collision energies as compared with the WP-EQM method. Specifically, at sufficiently high collision energies the reaction cannot be deemed to be statistical and important dynamical effects seem to be present. In general the WP-EQM results lie in between those obtained using the QCT and SQCT methods. One of the main

Quantum-mechanical computers and uncomputability

International Nuclear Information System (INIS)

Lloyd, S.

1993-01-01

The time evolution operator for any quantum-mechanical computer is diagonalizable, but to obtain the diagonal decomposition of a program state of the computer is as hard as actually performing the computation corresponding to the program. In particular, if a quantum-mechanical system is capable of universal computation, then the diagonal decomposition of program states is uncomputable. As a result, in a universe in which local variables support universal computation, a quantum-mechanical theory for that universe that supplies its spectrum cannot supply the spectral decomposition of the computational variables. A ''theory of everything'' can be simultaneously correct and fundamentally incomplete

Influence of grain orientation on evolution of surface features in fatigued polycrystalline copper: A comparison of thermal and uniaxial mechanical fatigue results

International Nuclear Information System (INIS)

Aicheler, Markus

2010-01-01

Surface state plays a major role in the crack nucleation process of pure metals in the High-Cycle-Fatigue (HCF) as well as in the Ultra-High-Cycle-Fatigue (UHCF) regime. Therefore, in studies dealing with HCF or UHCF, special attention is paid to the evolution of surface degradation during fatigue life. The accelerating structures of the future Compact Linear Collider (CLIC) under study at CERN will be submitted to a high number of thermal-mechanical fatigue cycles, arising from Radio Frequency (RF) induced eddy currents, causing local superficial cyclic heating. The number of cycles during the foreseen lifetime of CLIC reaches 2x10 11 . Fatigue may limit the lifetime of CLIC structures. In order to assess the effects of superficial fatigue, specific tests are defined and performed on polycrystalline Oxygen Free Electronic (OFE) grade Copper, a candidate material for the structures. Surface degradation depends on the orientation of near-surface grains. Copper samples thermally fatigued in two different fatigue experiments, pulsed laser and pulsed RF-heating, underwent postmortem Electron Backscattered Diffraction measurements. Samples fatigued by pulsed laser show the same trend in the orientation-fatigue damage behavior as samples fatigued by pulsed RF-heating. It is clearly observed that surface grains, oriented [1 1 1] with respect to the surface, show significantly more damage than surface grains oriented [1 0 0]. Results arising from a third fatigue experiment, the ultrasound (US) swinger, are compared to the results of the mentioned experiments. The US swinger is an uniaxial mechanical fatigue test enabling to apply within several days a total number of cycles representative of the life of the CLIC structures, thanks to a high repetition rate of 24 kHz. For comparison, laser fatigue experiments have much lower repetition rates. The dependence of surface degradation on grain orientation of samples tested by the US swinger was monitored during the fatigue life

Results from an International Simulation Study on Couples Thermal, Hydrological, and Mechanical (THM) Processes Near Geological Nuclear Waste Repositories

International Nuclear Information System (INIS)

J. Rutqvist; J.T. Birkholzer; M. Chijimatsu; O. Kolditz; Q.S. Liu; Y. Oda; W. Wang; C.Y. Zhang

2006-01-01

As part of the ongoing international code comparison project DECOVALEX, four research teams used five different models to simulate coupled thermal, hydrological, and mechanical (THM) processes near underground waste emplacement drifts. The simulations were conducted for two generic repository types with open or back-filled repository drifts under higher and lower post-closure temperature, respectively. In the completed first model inception phase of the project, a good agreement was achieved between the research teams in calculating THM responses for both repository types, although some disagreement in hydrological responses are currently being resolved. Good agreement in the basic thermal-mechanical responses was achieved for both repository types, even with some teams using relatively simplified thermal-elastic heat-conduction models that neglect complex near-field thermal-hydrological processes. The good agreement between the complex and simplified (and well-known) process models indicates that the basic thermal-mechanical responses can be predicted with a relatively high confidence level. The research teams have now moved on to the second phase of the project, the analysis of THM-induced permanent (irreversible) changes and the impact of those changes on the fluid flow field near an emplacement drift

Understanding the mechanical coupling between magma emplacement and the resulting deformation: the example of saucer-shaped sills

Science.gov (United States)

Galland, O.; Neumann, E. R.; Planke, S.

2009-12-01

The mechanical coupling between magma intrusions and the surrounding rocks plays a major role in the emplacement of volcanic plumbing systems. The deformation associated with magma emplacement has been widely studied, such as caldera inflation/deflation, volcano deformation during dike intrusion, and doming above laccoliths. However, the feedback processes, i.e. the effect of deformation resulting from intruding magma on the propagation of the intrusion itself, have rarely been studied. Saucer-shaped sills are adequate geological objects to understand such processes. Indeed, observation show that saucer-shaped sills are often associated with dome-like structures affecting the overlying sediments. In addition, there is a clear geometrical relation between the sills and the domes: the dome diameters are almost identical to those of saucers, and the tips of the inclined sheets of saucers are superimposed on the edges of the domes. In this presentation, we report on experimental investigations of the emplacement mechanisms of saucer-shaped sills and associated deformation. The model materials were (1) cohesive fine-grained silica flour, representing brittle crust, and (2) molten low-viscosity oil, representing magma. A weak layer located at the top of the injection inlet simulates strata. The main variable parameter is injection depth. During experiments, the surface of the model is digitalized through a structured light technique based on the moiré projection principle. Such a tool provides topographic maps of the surface of the model and allows a periodic (every 1.5 s) monitoring of the model topography. When the model magma starts intruding, a symmetrical dome rises above the inlet. Subsequently, the dome inflates and widens, and then evolves to a plateau-like feature, with nearly flat upper surface and steep sides. At the end of the experiments, the intruding liquid erupts at the edge of the plateau. The intrusions formed in the experiments are saucer-shaped sills

Respiratory mechanics and results of cytologic examination of bronchoalveolar lavage fluid in healthy adult alpacas.

Science.gov (United States)

Pacheco, Ana P; Bedenice, Daniela; Mazan, Melissa R; Hoffman, Andrew M

2012-01-01

To evaluate respiratory mechanical function and bronchoalveolar lavage (BAL) cytologic results in healthy alpacas. 16 client-owned adult alpacas. Measurements of pulmonary function were performed, including functional residual capacity (FRC) via helium dilution, respiratory system resistance via forced oscillatory technique (FOT), and assessment of breathing pattern by use of respiratory inductive plethysmography (RIP) in standing and sternally recumbent alpacas. Bronchoalveolar lavage was performed orotracheally during short-term anesthesia. Mean ± SD measurements of respiratory function were obtained in standing alpacas for FRC (3.19 ± 0.53 L), tidal volume (0.8 ± 0.13 L), and respiratory system resistance at 1 Hz (2.70 ± 0.88 cm H(2)O/L/s), 2 Hz (2.98 ± 0.70 cm H(2)O/L/s), 3 Hz (3.14 ± 0.77 cm H(2)O/L/s), 5 Hz (3.45 ± 0.91 cm H(2)O/L/s), and 7 Hz (3.84 ± 0.93 cm H(2)O/L/s). Mean phase angle, as a measurement of thoracoabdominal asynchrony, was 19.59 ± 10.06°, and mean difference between nasal and plethysmographic flow measurements was 0.18 ± 0.07 L/s. Tidal volume, peak inspiratory flow, and peak expiratory flow were significantly higher in sternally recumbent alpacas than in standing alpacas. Cytologic examination of BAL fluid revealed 58.52 ± 12.36% alveolar macrophages, 30.53 ± 13.78% lymphocytes, 10.95 ± 9.29% neutrophils, 0% mast cells, and several ciliated epithelial cells. Pulmonary function testing was tolerated well in nonsedated untrained alpacas. Bronchoalveolar lavage in alpacas yielded samples with adequate cellularity that had a greater abundance of neutrophils than has been reported in horses.

Mechanisms Design

DEFF Research Database (Denmark)

Restrepo-Giraldo, John Dairo

2006-01-01

Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design such mechan......Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design...... using criteria such as size, performance parameters, operation environment, etc. Content: Understanding Mechanisms Design (2 weeks) Definitions, mechanisms representations, kinematic diagrams, the four bar linkage, mobility, applications of mechanisms, types of mechanisms, special mechanisms, the design......: equations for various mechanisms. At the end of this module you will be able to analyze existing mechanisms and to describe their movement. Designing mechanisms (7 weeks) Type synthesis and dimensional synthesis, function generation, path generation, three precision points in multi-loop mechanisms...

Characterization of porosity in support of mechanical property analysis

International Nuclear Information System (INIS)

Price, R.H.; Martin, R.J. III; Boyd, P.J.

1992-01-01

Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sample tested. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results

Study the bonding mechanism of binders on hydroxyapatite surface and mechanical properties for 3DP fabrication bone scaffolds.

Science.gov (United States)

Wei, Qinghua; Wang, Yanen; Li, Xinpei; Yang, Mingming; Chai, Weihong; Wang, Kai; zhang, Yingfeng

2016-04-01

In 3DP fabricating artificial bone scaffolds process, the interaction mechanism between binder and bioceramics power determines the microstructure and macro mechanical properties of Hydroxyapatite (HA) bone scaffold. In this study, we applied Molecular Dynamics (MD) methods to investigating the bonding mechanism and essence of binders on the HA crystallographic planes for 3DP fabrication bone scaffolds. The cohesive energy densities of binders and the binding energies, PCFs g(r), mechanical properties of binder/HA interaction models were analyzed through the MD simulation. Additionally, we prepared the HA bone scaffold specimens with different glues by 3DP additive manufacturing, and tested their mechanical properties by the electronic universal testing machine. The simulation results revealed that the relationship of the binding energies between binders and HA surface is consistent with the cohesive energy densities of binders, which is PAM/HA>PVA/HA>PVP/HA. The PCFs g(r) indicated that their interfacial interactions mainly attribute to the ionic bonds and hydrogen bonds which formed between the polar atoms, functional groups in binder polymer and the Ca, -OH in HA. The results of mechanical experiments verified the relationship of Young׳s modulus for three interaction models in simulation, which is PVA/HA>PAM/HA>PVP/HA. But the trend of compressive strength is PAM/HA>PVA/HA>PVP/HA, this is consistent with the binding energies of simulation. Therefore, the Young׳s modulus of bone scaffolds are limited by the Young׳s modulus of binders, and the compressive strength is mainly decided by the viscosity of binder. Finally, the major reasons for differences in mechanical properties between simulation and experiment were found, the space among HA pellets and the incomplete infiltration of glue were the main reasons influencing the mechanical properties of 3DP fabrication HA bone scaffolds. These results provide useful information in choosing binder for 3DP fabrication

A mechanical wave system to show waveforms similar to quantum mechanical wavefunctions in a potential

International Nuclear Information System (INIS)

Faletič, Sergej

2015-01-01

Interviews with students suggest that even though they understand the formalism and the formal nature of quantum theory, they still often desire a mental picture of what the equations describe and some tangible experience with the wavefunctions. Here we discuss a mechanical wave system capable of reproducing correctly a mechanical equivalent of a quantum system in a potential, and the resulting waveforms in principle of any form. We have successfully reproduced the finite potential well, the potential barrier and the parabolic potential. We believe that these mechanical waveforms can provide a valuable experience base for introductory students to start from. We aim to show that mechanical systems that are described with the same mathematics as quantum mechanical, indeed behave in the same way. We believe that even if treated purely as a wave phenomenon, the system provides much insight into wave mechanics. This can be especially useful for physics teachers and others who often need to resort to concepts and experience rather than mathematics when explaining physical phenomena. (paper)

Mechanical Properties of Additively Manufactured Thick Honeycombs

Directory of Open Access Journals (Sweden)

Reza Hedayati

2016-07-01

Full Text Available Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson’s ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions.

Mechanical Devices Readiness FY04.0402.1

Energy Technology Data Exchange (ETDEWEB)

Bender, Thomas R.

2008-10-10

This Advanced Design and Production Technologies (ADAPT) project funded production process and tooling improvements to meet and sustain rate production for the program mechanism assemblies. Techniques were developed to allow evaluation and rework of sealed mechanisms that will result in prevention of the scrapping of future mechanisms. Future system mechanisms will likely be smaller with tighter tolerance parts that will require improved inspection equipment and techniques. During the latter phase of this project, the ISL (Intent Stronglink) PRT (Product Realization Team) developed designs and manufacturing processes at Sandia and at multiple KCP (Kansas City Plant) vendors, to produce glass ceramic headers to replace the brazed ceramic headers in the ISL. This achievement will result in significant production costs savings (unit cost and product scrap due to leaking headers).

Fracture Mechanics Prediction of Fatigue Life of Aluminum Highway Bridges

DEFF Research Database (Denmark)

Rom, Søren; Agerskov, Henning

2015-01-01

Fracture mechanics prediction of the fatigue life of aluminum highway bridges under random loading is studied. The fatigue life of welded joints has been determined from fracture mechanics analyses and the results obtained have been compared with results from experimental investigations. The fati......Fracture mechanics prediction of the fatigue life of aluminum highway bridges under random loading is studied. The fatigue life of welded joints has been determined from fracture mechanics analyses and the results obtained have been compared with results from experimental investigations...... against fatigue in aluminum bridges, may give results which are unconservative. Furthermore, it was in both investigations found that the validity of the results obtained from Miner's rule will depend on the distribution of the load history in tension and compression....

Agricultural mechanization policy and strategy : the case of Thailand

NARCIS (Netherlands)

Rijk, A.G.

1989-01-01

The role of agricultural mechanization in a developing economy is examined in order to enhance the formulation of mechanization policy and strategy. As a result of the review and assessment of the mechanization process, seven distinct stages in the mechanization process are specified and

Mechanical design and first experimental results of an upgraded technical PERMCAT reactor for tritium recovery in the fuel cycle of a fusion machine

Energy Technology Data Exchange (ETDEWEB)

Welte, S., E-mail: stefan.welte@kit.edu [Karlsruhe Institute of Technology (KIT), Forschungszentrum Karlsruhe, Institute for Technical Physics, Tritium Laboratory Karlsruhe, Hermann v. Helmholtz Platz 1, 76344 Eggenstein Leopoldshafen (Germany); Demange, D.; Wagner, R. [Karlsruhe Institute of Technology (KIT), Forschungszentrum Karlsruhe, Institute for Technical Physics, Tritium Laboratory Karlsruhe, Hermann v. Helmholtz Platz 1, 76344 Eggenstein Leopoldshafen (Germany)

2010-12-15

The PERMCAT process developed for the final clean-up stage of the Tokamak Exhaust Processing systems of the ITER tritium plant combines a catalytic reactor and a Pd/Ag permeator in a single component. A first generation technical PERMCAT has been successfully operated as part of the CAPER experiment at the Tritium Laboratory Karlsruhe for several years. Various alternative PERMCAT mechanical designs were proposed and studied on small-scale prototypes. An upgraded technical PERMCAT reactor was designed, manufactured and commissioned with deuterium. A parallel arrangement of finger-type membranes inserted in a single catalyst bed design was chosen to simplify the geometry and the manufacturing while improving the robustness of the reactor. The component has been designed and manufactured to be fully tritium compatible and also fully compatible with both process and electrical connections of the previous PERMCAT to be replaced. The new PERMCAT mechanical design is more compact and easy to manufacture. This PERMCAT reactor was submitted to functional tests and experiments based on isotopic exchanges between H{sub 2}O and D{sub 2} to measure the processing performances. The first experimental results show decontamination factors versus flow rates better than all previously measured.

Mechanical design and first experimental results of an upgraded technical PERMCAT reactor for tritium recovery in the fuel cycle of a fusion machine

International Nuclear Information System (INIS)

Welte, S.; Demange, D.; Wagner, R.

2010-01-01

The PERMCAT process developed for the final clean-up stage of the Tokamak Exhaust Processing systems of the ITER tritium plant combines a catalytic reactor and a Pd/Ag permeator in a single component. A first generation technical PERMCAT has been successfully operated as part of the CAPER experiment at the Tritium Laboratory Karlsruhe for several years. Various alternative PERMCAT mechanical designs were proposed and studied on small-scale prototypes. An upgraded technical PERMCAT reactor was designed, manufactured and commissioned with deuterium. A parallel arrangement of finger-type membranes inserted in a single catalyst bed design was chosen to simplify the geometry and the manufacturing while improving the robustness of the reactor. The component has been designed and manufactured to be fully tritium compatible and also fully compatible with both process and electrical connections of the previous PERMCAT to be replaced. The new PERMCAT mechanical design is more compact and easy to manufacture. This PERMCAT reactor was submitted to functional tests and experiments based on isotopic exchanges between H 2 O and D 2 to measure the processing performances. The first experimental results show decontamination factors versus flow rates better than all previously measured.

Tolerance Optimization for Mechanisms with Lubricated Joints

International Nuclear Information System (INIS)

Choi, J.-H.; Lee, S.J.; Choi, D.-H.

1998-01-01

This paper addresses an analytical approach to tolerance optimization for planar mechanisms with lubricated joints based on mechanical error analysis. The mobility method is applied to consider the lubrication effects at joints and planar mechanisms are stochastically defined by using the clearance vector model for mechanical error analysis. The uncertainties considered in the analysis are tolerances on link lengths and radial clearances and these are selected as design variables. To show the validity of the proposed method for mechanical error analysis, it is applied to two examples, and the results obtained are compared with those of Monte Carlo simulations. Based on the mechanical error analysis, tolerance optimizations are applied to the examples

RESULTS, RESPONSIBILITY, FAULT AND CONTROL

Directory of Open Access Journals (Sweden)

Evgeniy Stoyanov

2016-09-01

Full Text Available The paper focuses on the responsibility arising from the registered financial results. The analysis of this responsibility presupposes its evaluation and determination of the role of fault in the formation of negative results. The search for efficiency in this whole process is justified by the understanding of the mechanisms that regulate the behavior of economic actors.

Supersymmetry and quantum mechanics

International Nuclear Information System (INIS)

Cooper, F.; Sukhatme, U.

1995-01-01

In the past ten years, the ideas of supersymmetry have been profitably applied to many nonrelativistic quantum mechanical problems. In particular, there is now a much deeper understanding of why certain potentials are analytically solvable and an array of powerful new approximation methods for handling potentials which are not exactly solvable. In this report, we review the theoretical formulation of supersymmetric quantum mechanics and discuss many applications. Exactly solvable potentials can be understood in terms of a few basic ideas which include supersymmetric partner potentials, shape invariance and operator transformations. Familiar solvable potentials all have the property of shape invariance. We describe new exactly solvable shape invariant potentials which include the recently discovered self-similar potentials as a special case. The connection between inverse scattering, isospectral potentials and supersymmetric quantum mechanics is discussed and multi-soliton solutions of the KdV equation are constructed. Approximation methods are also discussed within the framework of supersymmetric quantum mechanics and in particular it is shown that a supersymmetry inspired WKB approximation is exact for a class of shape invariant potentials. Supersymmetry ideas give particularly nice results for the tunneling rate in a double well potential and for improving large N expansions. We also discuss the problem of a charged Dirac particle in an external magnetic field and other potentials in terms of supersymmetric quantum mechanics. Finally, we discuss structures more general than supersymmetric quantum mechanics such as parasupersymmetric quantum mechanics in which there is a symmetry between a boson and a para-fermion of order p. ((orig.))

Planar articulated mechanism design by graph theoretical enumeration

DEFF Research Database (Denmark)

Kawamoto, A; Bendsøe, Martin P.; Sigmund, Ole

2004-01-01

This paper deals with design of articulated mechanisms using a truss-based ground-structure representation. By applying a graph theoretical enumeration approach we can perform an exhaustive analysis of all possible topologies for a test example for which we seek a symmetric mechanism. This guaran....... This guarantees that one can identify the global optimum solution. The result underlines the importance of mechanism topology and gives insight into the issues specific to articulated mechanism designs compared to compliant mechanism designs....

COMIC COMMUNICATION MECHANISM AS AN INTENTIONAL-MOTIVATED CONTAMINATION

OpenAIRE

Musiychuk, Maria

2015-01-01

A communicative mechanism described as a comic-motivated intentional contamination that means a change as a result of cross-breeding different words or expressions of similar sounding, construction, and meaning. This mechanism is realized through the transfer of communicative intention, i.e. resulting motives and goals of the communication.

Continuum mechanics

CERN Document Server

Spencer, A J M

2004-01-01

The mechanics of fluids and the mechanics of solids represent the two major areas of physics and applied mathematics that meet in continuum mechanics, a field that forms the foundation of civil and mechanical engineering. This unified approach to the teaching of fluid and solid mechanics focuses on the general mechanical principles that apply to all materials. Students who have familiarized themselves with the basic principles can go on to specialize in any of the different branches of continuum mechanics. This text opens with introductory chapters on matrix algebra, vectors and Cartesian ten

Topological Higgs mechanism with ordinary Higgs mechanism

International Nuclear Information System (INIS)

Oda Ichiro; Yahikozawa Shigeaki.

1989-12-01

Topological Higgs mechanism in higher dimensions is analyzed when ordinary Higgs potential exists. It is shown that if one-form B-field becomes massive by the ordinary Higgs mechanism, another D-2 form C-field also becomes massive through topological term in addition to the topological mass generation by the topological Higgs mechanism. Moreover we investigate this mechanism in three dimensional theories, that is to say, Chern-Simons theory and more general theory. (author). 10 refs

Analytical mechanics for relativity and quantum mechanics

CERN Document Server

Johns, Oliver Davis

2011-01-01

Analytical Mechanics for Relativity and Quantum Mechanics is an innovative and mathematically sound treatment of the foundations of analytical mechanics and the relation of classical mechanics to relativity and quantum theory. It is intended for use at the introductory graduate level. A distinguishing feature of the book is its integration of special relativity into teaching of classical mechanics. After a thorough review of the traditional theory, Part II of the book introduces extended Lagrangian and Hamiltonian methods that treat time as a transformable coordinate rather than the fixed parameter of Newtonian physics. Advanced topics such as covariant Langrangians and Hamiltonians, canonical transformations, and Hamilton-Jacobi methods are simplified by the use of this extended theory. And the definition of canonical transformation no longer excludes the Lorenz transformation of special relativity. This is also a book for those who study analytical mechanics to prepare for a critical exploration of quantum...

Memory mechanisms supporting syntactic comprehension.

Science.gov (United States)

Caplan, David; Waters, Gloria

2013-04-01

Efforts to characterize the memory system that supports sentence comprehension have historically drawn extensively on short-term memory as a source of mechanisms that might apply to sentences. The focus of these efforts has changed significantly in the past decade. As a result of changes in models of short-term working memory (ST-WM) and developments in models of sentence comprehension, the effort to relate entire components of an ST-WM system, such as those in the model developed by Baddeley (Nature Reviews Neuroscience 4: 829-839, 2003) to sentence comprehension has largely been replaced by an effort to relate more specific mechanisms found in modern models of ST-WM to memory processes that support one aspect of sentence comprehension--the assignment of syntactic structure (parsing) and its use in determining sentence meaning (interpretation) during sentence comprehension. In this article, we present the historical background to recent studies of the memory mechanisms that support parsing and interpretation and review recent research into this relation. We argue that the results of this research do not converge on a set of mechanisms derived from ST-WM that apply to parsing and interpretation. We argue that the memory mechanisms supporting parsing and interpretation have features that characterize another memory system that has been postulated to account for skilled performance-long-term working memory. We propose a model of the relation of different aspects of parsing and interpretation to ST-WM and long-term working memory.

Handedness results from Complementary Hemispheric Dominance, not Global Hemispheric Dominance: Evidence from Mechanically Coupled Bilateral Movements.

Science.gov (United States)

Woytowicz, Elizabeth J; Westlake, Kelly P; Whitall, Jill; Sainburg, Robert L

2018-05-09

Two contrasting views of handedness can be described as 1) complementary dominance, in which each hemisphere is specialized for different aspects of motor control, and 2) global dominance, in which the hemisphere contralateral to the dominant arm is specialized for all aspects of motor control. The present study sought to determine which motor lateralization hypothesis best predicts motor performance during common bilateral task of stabilizing an object (e.g. bread) with one hand while applying forces to the object (e.g. slicing) using the other hand. We designed an experimental equivalent of this task, performed in a virtual environment with the unseen arms supported by frictionless air-sleds. The hands were connected by a spring, and the task was to maintain the position of one hand, while moving the other hand to a target. Thus, the reaching hand was required to take account of the spring load to make smooth and accurate trajectories, while the stabilizer hand was required to impede the spring load to keep a constant position. Right-handed subjects performed two task sessions (right hand reach and left hand stabilize; left hand reach and right hand stabilize) with the order of the sessions counterbalanced between groups. Our results indicate a hand by task-component interaction, such that the right hand showed straighter reaching performance while the left showed more stable holding performance. These findings provide support for the complementary dominance hypothesis and suggest that the specializations of each cerebral hemisphere for impedance and dynamic control mechanisms are expressed during bilateral interactive tasks.

Mechanics of bioinspired imaging systems

Directory of Open Access Journals (Sweden)

Zhengwei Li

2016-01-01

Full Text Available Imaging systems in nature have attracted a lot of research interest due to their superior optical and imaging characteristics. Recent advancements in materials science, mechanics, and stretchable electronics have led to successful development of bioinspired cameras that resemble the structures and functions of biological light-sensing organs. In this review, we discuss some recent progresses in mechanics of bioinspired imaging systems, including tunable hemispherical eyeball camera and artificial compound eye camera. The mechanics models and results reviewed in this article can provide efficient tools for design and optimization of such systems, as well as other related optoelectronic systems that combine rigid elements with soft substrates.

Pseudospectra in non-Hermitian quantum mechanics

Science.gov (United States)

Krejčiřík, D.; Siegl, P.; Tater, M.; Viola, J.

2015-10-01

We propose giving the mathematical concept of the pseudospectrum a central role in quantum mechanics with non-Hermitian operators. We relate pseudospectral properties to quasi-Hermiticity, similarity to self-adjoint operators, and basis properties of eigenfunctions. The abstract results are illustrated by unexpected wild properties of operators familiar from PT -symmetric quantum mechanics.

Parallel evolution under chemotherapy pressure in 29 breast cancer cell lines results in dissimilar mechanisms of resistance.

Directory of Open Access Journals (Sweden)

Bálint Tegze

Full Text Available BACKGROUND: Developing chemotherapy resistant cell lines can help to identify markers of resistance. Instead of using a panel of highly heterogeneous cell lines, we assumed that truly robust and convergent pattern of resistance can be identified in multiple parallel engineered derivatives of only a few parental cell lines. METHODS: Parallel cell populations were initiated for two breast cancer cell lines (MDA-MB-231 and MCF-7 and these were treated independently for 18 months with doxorubicin or paclitaxel. IC50 values against 4 chemotherapy agents were determined to measure cross-resistance. Chromosomal instability and karyotypic changes were determined by cytogenetics. TaqMan RT-PCR measurements were performed for resistance-candidate genes. Pgp activity was measured by FACS. RESULTS: All together 16 doxorubicin- and 13 paclitaxel-treated cell lines were developed showing 2-46 fold and 3-28 fold increase in resistance, respectively. The RT-PCR and FACS analyses confirmed changes in tubulin isofom composition, TOP2A and MVP expression and activity of transport pumps (ABCB1, ABCG2. Cytogenetics showed less chromosomes but more structural aberrations in the resistant cells. CONCLUSION: We surpassed previous studies by parallel developing a massive number of cell lines to investigate chemoresistance. While the heterogeneity caused evolution of multiple resistant clones with different resistance characteristics, the activation of only a few mechanisms were sufficient in one cell line to achieve resistance.

Thermal behaviors of mechanically activated pyrites by thermogravimetry (TG)

International Nuclear Information System (INIS)

Hu Huiping; Chen Qiyuan; Yin Zhoulan; Zhang Pingmin

2003-01-01

The thermal decompositions of mechanically activated and non-activated pyrites were studied by thermogravimetry (TG) at the heating rate of 10 K min -1 in argon. Results indicate that the initial temperature of thermal decomposition (T di ) in TG curves for mechanically activated pyrites decreases gradually with increasing the grinding time. The specific granulometric surface area (S G ), the structural disorder of mechanically activated pyrites were analyzed by X-ray diffraction laser particle size analyzer, and X-ray powder diffraction analysis (XRD), respectively. The results show that the S G of mechanically activated pyrites remains almost constant after a certain grinding time, and lattice distortions (ε) rise but the crystallite sizes (D) decrease with increasing the grinding time. All these results imply that the decrease of T di in TG curves of mechanically activated pyrites is mainly caused by the increase of lattice distortions ε and the decrease of the crystallite sizes D of mechanically activated pyrite with increasing the grinding time. The differences in the reactivity between non-activated and mechanically activated pyrites were observed using characterization of the products obtained from 1 h treatment of non-activated and mechanically activated pyrites at 713 K under inert atmosphere and characterization of non-activated and mechanically activated pyrites exposed to ambient air for a certain period

Mechanical stop mechanism for overcoming MEMS fabrication tolerances

International Nuclear Information System (INIS)

Hussein, Hussein; Bourbon, Gilles; Le Moal, Patrice; Lutz, Philippe; Haddab, Yassine

2017-01-01

A mechanical stop mechanism is developed in order to compensate MEMS fabrication tolerances in discrete positioning. The mechanical stop mechanism is designed to be implemented on SOI wafers using a common DRIE etching process. The various fabrication tolerances obtained due to the etching process are presented and discussed in the paper. The principle and design of the mechanism are then presented. Finally, experiments on microfabricated positioning prototypes show accurate steps unaffected by the fabrication tolerances. (technical note)

Mechanics of additively manufactured biomaterials.

Science.gov (United States)

Zadpoor, Amir A

2017-06-01

Additive manufacturing (3D printing) has found many applications in healthcare including fabrication of biomaterials as well as bioprinting of tissues and organs. Additively manufactured (AM) biomaterials may possess arbitrarily complex micro-architectures that give rise to novel mechanical, physical, and biological properties. The mechanical behavior of such porous biomaterials including their quasi-static mechanical properties and fatigue resistance is not yet well understood. It is particularly important to understand the relationship between the designed micro-architecture (topology) and the resulting mechanical properties. The current special issue is dedicated to understanding the mechanical behavior of AM biomaterials. Although various types of AM biomaterials are represented in the special issue, the primary focus is on AM porous metallic biomaterials. As a prelude to this special issue, this editorial reviews some of the latest findings in the mechanical behavior of AM porous metallic biomaterials so as to describe the current state-of-the-art and set the stage for the other studies appearing in the issue. Some areas that are important for future research are also briefly mentioned. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fundamentals of Quantum Mechanics

Science.gov (United States)

Tang, C. L.

2005-06-01

Quantum mechanics has evolved from a subject of study in pure physics to one with a wide range of applications in many diverse fields. The basic concepts of quantum mechanics are explained in this book in a concise and easy-to-read manner emphasising applications in solid state electronics and modern optics. Following a logical sequence, the book is focused on the key ideas and is conceptually and mathematically self-contained. The fundamental principles of quantum mechanics are illustrated by showing their application to systems such as the hydrogen atom, multi-electron ions and atoms, the formation of simple organic molecules and crystalline solids of practical importance. It leads on from these basic concepts to discuss some of the most important applications in modern semiconductor electronics and optics. Containing many homework problems and worked examples, the book is suitable for senior-level undergraduate and graduate level students in electrical engineering, materials science and applied physics. Clear exposition of quantum mechanics written in a concise and accessible style Precise physical interpretation of the mathematical foundations of quantum mechanics Illustrates the important concepts and results by reference to real-world examples in electronics and optoelectronics Contains homeworks and worked examples, with solutions available for instructors

Novel sensing approach for LPG leakage detection: Part I: Operating Mechanism and Preliminary Results

KAUST Repository

Mukhopadhyay, Subhas; Nag, Anindya; Zia, Asif; Li, Xie; Kosel, Jü rgen

2015-01-01

Gas sensing technology has been among the topical research work for quite some time. This paper showcases the research done on the detection mechanism of leakage of domestic cooking gas at ambient conditions. MEMS-based interdigital sensors were fabricated on oxidized single crystal silicon surfaces by maskless photolithography technique. The electrochemical impedance analysis of these sensors was done to detect liquefied petroleum gas (LPG) with and without coated particles of tin oxide (SnO2) in form of thin layer.A thin-film of SnO2 was spin-coated on the sensing surface of the interdigital sensor to induce selectivity to LPG that consists of a 60/40 mixture of propane and butane respectively. The paper reports a novel strategy for gas detection under ambient temperature and humidity conditions. The response time of the coated sensor was encouraging and own a promising potential to the development of a complete efficient gas sensing system.

Novel sensing approach for LPG leakage detection: Part I: Operating Mechanism and Preliminary Results

KAUST Repository

Mukhopadhyay, Subhas

2015-10-30

Gas sensing technology has been among the topical research work for quite some time. This paper showcases the research done on the detection mechanism of leakage of domestic cooking gas at ambient conditions. MEMS-based interdigital sensors were fabricated on oxidized single crystal silicon surfaces by maskless photolithography technique. The electrochemical impedance analysis of these sensors was done to detect liquefied petroleum gas (LPG) with and without coated particles of tin oxide (SnO2) in form of thin layer.A thin-film of SnO2 was spin-coated on the sensing surface of the interdigital sensor to induce selectivity to LPG that consists of a 60/40 mixture of propane and butane respectively. The paper reports a novel strategy for gas detection under ambient temperature and humidity conditions. The response time of the coated sensor was encouraging and own a promising potential to the development of a complete efficient gas sensing system.

Design and optimization of a bend-and-sweep compliant mechanism

International Nuclear Information System (INIS)

Tummala, Y; Frecker, M I; Wissa, A A; Hubbard Jr, J E

2013-01-01

A novel contact aided compliant mechanism called bend-and-sweep compliant mechanism is presented in this paper. This mechanism has nonlinear stiffness properties in two orthogonal directions. An angled compliant joint (ACJ) is the fundamental element of this mechanism. Geometric parameters of ACJs determine the stiffness of the compliant mechanism. This paper presents the design and optimization of bend-and-sweep compliant mechanism. A multi-objective optimization problem was formulated for design optimization of the bend-and-sweep compliant mechanism. The objectives of the optimization problem were to maximize or minimize the bending and sweep displacements, depending on the situation, while minimizing the von Mises stress and mass of each mechanism. This optimization problem was solved using NSGA-II (a genetic algorithm). The results of this optimization for a single ACJ during upstroke and downstroke are presented in this paper. Results of two different loading conditions used during optimization of a single ACJ for upstroke are presented. Finally, optimization results comparing the performance of compliant mechanisms with one and two ACJs are also presented. It can be inferred from these results that the number of ACJs and the design of each ACJ determines the stiffness of the bend-and-sweep compliant mechanism. These mechanisms can be used in various applications. The goal of this research is to improve the performance of ornithopters by passively morphing their wings. In order to achieve a bio-inspired wing gait called continuous vortex gait, the wings of the ornithopter need to bend, and sweep simultaneously. This can be achieved by inserting the bend-and-sweep compliant mechanism into the leading edge wing spar of the ornithopters. (paper)

Puzzling Mechanisms

Science.gov (United States)

van Deventer, M. Oskar

2009-01-01

The basis of a good mechanical puzzle is often a puzzling mechanism. This article will introduce some new puzzling mechanisms, like two knots that engage like gears, a chain whose links can be interchanged, and flat gears that do not come apart. It illustrates how puzzling mechanisms can be transformed into real mechanical puzzles, e.g., by…

Structured Mechanical Collage.

Science.gov (United States)

Huang, Zhe; Wang, Jiang; Fu, Hongbo; Lau, Rynson W H

2014-07-01

We present a method to build 3D structured mechanical collages consisting of numerous elements from the database given artist-designed proxy models. The construction is guided by some graphic design principles, namely unity, variety and contrast. Our results are visually more pleasing than previous works as confirmed by a user study.

Investigation of the Biochemical Mechanism for Cell-Substrate Mechanical Sensing

Science.gov (United States)

Ricotta, Vincent Anthony

Advancements in stem cell biology and materials science have enabled the development of new treatments for tissue repair. Dental pulp stem cells (DPSCs), which are highly proliferative and can be induced to differentiate along several mesenchymal cell lineages, offer the possibility for pulpal regeneration and treatment of injured dentition. Polybutadiene (PB) may be used as a substrate for these cells. This elastomer can be spun casted into films of different thicknesses with different moduli. DPSCs grown on PB films, which are relatively hard (less than 1500 A thick), biomineralize depositing crystalline calcium phosphate without a requirement for the typical induction factor, dexamethasone (Dex). The moduli of cells track with the moduli of the surface suggesting that mechanics controls mineralization. The purpose of this study was to determine whether the major effect of Dex on biomineralization is the result of its ability to alter cell mechanics or its ability to induce osteogenesis/odontogenesis. DPSCs sense substrate mechanics through the focal adhesions, whose function is in part regulated by the Ras homolog gene (Rho) and its downstream effectors Rho associated kinases (ROCKs). ROCKs control actin filament polymerization and interactions with myosin light chain. Because cells sense substrate mechanics through focal adhesion proteins whose function is regulated by ROCKs, the impact of a ROCK inhibitor, Y-27632, was monitored. Blocking this pathway with Y-27632 suppressed the ability of DPSCs to sense the PB substrate. The cell modulus, plasma membrane stiffness, and cytosol stiffness were all lowered and biomineralization was suppressed in all cultures independent of substrate modulus or the presence of Dex. In other words, the inability of DPSCs to sense mechanical cues suppressed their ability to promote mineralization. On the other hand the expression of osteogenic/odontogenic markers (alkaline phosphatase and osteocalcin) was enhanced, perhaps due to Y

Mechanical response of biopolymer double networks

Science.gov (United States)

Carroll, Joshua; Das, Moumita

We investigate a double network model of articular cartilage (AC) and characterize its equilibrium mechanical response. AC has very few cells and the extracellular matrix mainly determines its mechanical response. This matrix can be thought of as a double polymer network made of collagen and aggrecan. The collagen fibers are stiff and resist tension and compression forces, while aggrecans are flexible and control swelling and hydration. We construct a microscopic model made of two interconnected disordered polymer networks, with fiber elasticity chosen to qualitatively mimic the experimental system. We study the collective mechanical response of this double network as a function of the concentration and stiffness of the individual components as well as the strength of the connection between them using rigidity percolation theory. Our results may provide a better understanding of mechanisms underlying the mechanical resilience of AC, and more broadly may also lead to new perspectives on the mechanical response of multicomponent soft materials. This work was partially supported by a Cottrell College Science Award.

Control mechanisms in franchise systems

OpenAIRE

Hass, Jörg

2012-01-01

This dissertation answers the question which different control mechanisms exist in a franchise system. It is the first two-sided franchise empirical analysis, regarding all outlets of the franchise system (franchisees and company-owned) as well as the franchisor. On the theoretical side, this dissertation integrates the two main management theories: principal-agent-theory and transaction cost analysis. The results show that there are used different control mechanisms in a franchise sys...

Nature-Inspired Fluid Mechanics Results of the DFG Priority Programme 1207 ”Nature-inspired Fluid Mechanics” 2006-2012

CERN Document Server

Bleckmann, Horst

2012-01-01

This book is the closing report of the national priority program Nature-Inspired Fluid Mechanics (Schwerpunktprogramm SPP 1207: Strömungsbeeinflussung in der Natur und Technik). Nature-inspired fluid mechanics is one subset of biomimetics, a discipline which has received increased attention over the last decade, with numerous faculties and degree courses devoted solely to exploring ‘nature as a model’ for engineering applications. To save locomotion energy, evolution has optimized the design of animals such that friction loss is minimized. In addition to many morphological adaptations, animals that are often exposed to water or air currents have developed special behaviors that allow them to use the energy contained in air or water fluctuations for energy savings. Such flow manipulation and control is not only important for many animals, but also for many engineering applications. Since living beings have been optimized by several million years of evolution it is very likely that many engineering discipl...

Mechanics of couple-stress fluid coatings

Science.gov (United States)

Waxman, A. M.

1982-01-01

The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.

Topological fluid mechanics of Axisymmetric Flow

DEFF Research Database (Denmark)

Brøns, Morten

1998-01-01

Topological fluid mechanics in the sense of the present paper is the study and classification of flow patterns close to a critical point. Here we discuss the topology of steady viscous incompressible axisymmetric flows in the vicinity of the axis. Following previous studies the velocity field v...... to the authors knowledge has not been used systematically to high orders in topological fluid mechanics. We compare the general results with experimental and computational results on the Vogel-Ronneberg flow. We show that the topology changes observed when recirculating bubbles on the vortex axis are created...

Optomechanical transistor with mechanical gain

Science.gov (United States)

Zhang, X. Z.; Tian, Lin; Li, Yong

2018-04-01

We study an optomechanical transistor, where an input field can be transferred and amplified unidirectionally in a cyclic three-mode optomechanical system. In this system, the mechanical resonator is coupled simultaneously to two cavity modes. We show that it only requires a finite mechanical gain to achieve the nonreciprocal amplification. Here the nonreciprocity is caused by the phase difference between the linearized optomechanical couplings that breaks the time-reversal symmetry of this system. The amplification arises from the mechanical gain, which provides an effective phonon bath that pumps the mechanical mode coherently. This effect is analogous to the stimulated emission of atoms, where the probe field can be amplified when its frequency is in resonance with that of the anti-Stokes transition. We show that by choosing optimal parameters, this optomechanical transistor can reach perfect unidirectionality accompanied with strong amplification. In addition, the presence of the mechanical gain can result in ultralong delay in the phase of the probe field, which provides an alternative to controlling light transport in optomechanical systems.

Electro-chemo-mechanical response of a free-standing polypyrrole strip

International Nuclear Information System (INIS)

Vazquez, G; Otero, T F; Cascales, J J L

2008-01-01

Further development of mechanical devices based on conducting polymers; require a precise understanding of their mechanical response, i.e. their control, under a controlled external current. In this work, we show some results for the relation between the electrical current consumed in the electrochemical process and the mechanical work developed by a freestanding polypyrrole strip, when it is subjected to a stretching force (stress). Under these conditions, from the results obtained in this work, we observe how it results almost impossible to predict a straight relationship between mechanical work and current consumed in the electrochemical process. In addition, we will quantify the variation of the mechanical properties of the free standing polypyrrole strip associated with the oxidation state of the polymer by measuring its Young's modulus.

Classical Mechanics as Nonlinear Quantum Mechanics

International Nuclear Information System (INIS)

Nikolic, Hrvoje

2007-01-01

All measurable predictions of classical mechanics can be reproduced from a quantum-like interpretation of a nonlinear Schroedinger equation. The key observation leading to classical physics is the fact that a wave function that satisfies a linear equation is real and positive, rather than complex. This has profound implications on the role of the Bohmian classical-like interpretation of linear quantum mechanics, as well as on the possibilities to find a consistent interpretation of arbitrary nonlinear generalizations of quantum mechanics

Quantum mechanics as applied mathematical statistics

International Nuclear Information System (INIS)

Skala, L.; Cizek, J.; Kapsa, V.

2011-01-01

Basic mathematical apparatus of quantum mechanics like the wave function, probability density, probability density current, coordinate and momentum operators, corresponding commutation relation, Schroedinger equation, kinetic energy, uncertainty relations and continuity equation is discussed from the point of view of mathematical statistics. It is shown that the basic structure of quantum mechanics can be understood as generalization of classical mechanics in which the statistical character of results of measurement of the coordinate and momentum is taken into account and the most important general properties of statistical theories are correctly respected.

Pitfall in quantum mechanical/molecular mechanical molecular dynamics simulation of small solutes in solution.

Science.gov (United States)

Hu, Hao; Liu, Haiyan

2013-05-30

Developments in computing hardware and algorithms have made direct molecular dynamics simulation with the combined quantum mechanical/molecular mechanical methods affordable for small solute molecules in solution, in which much improved accuracy can be obtained via the quantum mechanical treatment of the solute molecule and even sometimes water molecules in the first solvation shell. However, unlike the conventional molecular mechanical simulations of large molecules, e.g., proteins, in solutions, special care must be taken in the technical details of the simulation, including the thermostat of the solute/solvent system, so that the conformational space of the solute molecules can be properly sampled. We show here that the common setup for classical molecular mechanical molecular dynamics simulations, such as the Berendsen or single Nose-Hoover thermostat, and/or rigid water models could lead to pathological sampling of the solutes' conformation. In the extreme example of a methanol molecule in aqueous solution, improper and sluggish setups could generate two peaks in the distribution of the O-H bond length. We discuss the factors responsible for this somewhat unexpected result and evoke a simple and ancient technical fix-up to resolve this problem.

Oxidation of coals in the course of mechanical treatment

Energy Technology Data Exchange (ETDEWEB)

A.G. Proidakov; G.A. Kalabin [Irkutsk State University, Irkutsk (Russian Federation)

2009-04-15

The results of a study of coal oxidation under stationary conditions and during mechanical treatment are presented. A considerable increase in the reaction rate constants of coal oxidation during mechanical treatment because of oxidative mechanical degradation was found.

Thermodynamic limit and decoherence: rigorous results

Energy Technology Data Exchange (ETDEWEB)

Frasca, Marco [Via Erasmo Gattamelata 3, 00176 Rome (Italy)

2007-05-15

Time evolution operator in quantum mechanics can be changed into a statistical operator by a Wick rotation. This strict relation between statistical mechanics and quantum evolution can reveal deep results when the thermodynamic limit is considered. These results translate in a set of theorems proving that these effects can be effectively at work producing an emerging classical world without recurring to any external entity that in some cases cannot be properly defined. For a many-body system it has been recently shown that Gaussian decay of the coherence is the rule with a duration of recurrence more and more small as the number of particles increases. This effect has been observed experimentally. More generally, a theorem about coherence of bulk matter can be proved. All this takes us to the conclusion that a well defined boundary for the quantum to classical world does exist and that can be drawn by the thermodynamic limit, extending in this way the deep link between statistical mechanics and quantum evolution to a high degree.

Bananaworld quantum mechanics for primates

CERN Document Server

Bub, Jeffrey

2016-01-01

What on earth do bananas have to do with quantum mechanics? From a modern perspective, quantum mechanics is about strangely counterintuitive correlations between separated systems, which can be exploited in feats like quantum teleportation, unbreakable cryptographic schemes, and computers with enormously enhanced computing power. Schro?dinger coined the term "entanglement" to describe these bizarre correlations. Bananaworld -- an imaginary island with "entangled" bananas -- brings to life the fascinating discoveries of the new field of quantum information without the mathematical machinery of quantum mechanics. The connection with quantum correlations is fully explained in sections written for the non-physicist reader with a serious interest in understanding the mysteries of the quantum world. The result is a subversive but entertaining book that is accessible and interesting to a wide range of readers, with the novel thesis that quantum mechanics is about the structure of information. What we have discovered...

Quantum mechanics

International Nuclear Information System (INIS)

Anon.

1990-01-01

The book is on quantum mechanics. The emphasis is on the basic concepts and the methodology. The chapters include: Breakdown of classical concepts; Quantum mechanical concepts; Basic postulates of quantum mechanics; solution of problems in quantum mechanics; Simple harmonic oscillator; and Angular Momentum

Ludwig Boltzmann, mechanics and vitalism

International Nuclear Information System (INIS)

Broda, E.

1990-01-01

During most of his life Boltzmann considered classical mechanics, based on the ideas of material points and central forces, as the fundament of physics. On this basis he became one of the founders of Statistical Mechanics, through which thermodynamics was interpreted on an atomistic basis. In this work, Boltzmann was opposed by his colleague, Ernst Mach. Boltzmann also devoted much work to attempts to interpret Maxwell's theory of the electromagnetic field, of which he was a main protagonist in Central Europe, through mechanics. However, as a supporter of mechanics Boltzmann was by no means dogmatic. While he was adamant in his rejection of Wilhelm Ostwald's energism, he was openminded in respect to the relationship of mechanics, electromagnetism and atomistics. Personally, Boltzmann wanted to conserve and transmit the enormous achievements of mechanics, especially in connection with the mechanical theory of heat, so that these results should not be lost to future generations, but he encouraged attempts to proceed in new directions. While within the framework of statistical mechanics the atoms were treated like the material points of classical mechanics, Boltzmann resisted the initial, unwarranted, ideas about the structure and the properties of the atoms. When later valid ideas were evolved, Boltzmann warmly welcomed this progress, without however personally taking part in the new developments. In his later years, Boltzmann took an intense interest in biology. He supported Darwin's theories, and he contributed to them. He may be called an 'absolute Darwinist'. In his search for a natural explanation of the phenomena of life, he used the term 'mechanical', without meaning to limit them to the realm of classical mechanics. This terminological laxity is considered as unfortunate. Extending his application of Darwinian principles to advanced species, including man, Boltzmann put forward 'mechanical' explanations of thought, of morality, of the sense of beauty, and of

Mechanical stimulation induces mTOR signaling via an ERK-independent mechanism: implications for a direct activation of mTOR by phosphatidic acid.

Directory of Open Access Journals (Sweden)

Jae Sung You

Full Text Available Signaling by mTOR is a well-recognized component of the pathway through which mechanical signals regulate protein synthesis and muscle mass. However, the mechanisms involved in the mechanical regulation of mTOR signaling have not been defined. Nevertheless, recent studies suggest that a mechanically-induced increase in phosphatidic acid (PA may be involved. There is also evidence which suggests that mechanical stimuli, and PA, utilize ERK to induce mTOR signaling. Hence, we reasoned that a mechanically-induced increase in PA might promote mTOR signaling via an ERK-dependent mechanism. To test this, we subjected mouse skeletal muscles to mechanical stimulation in the presence or absence of a MEK/ERK inhibitor, and then measured several commonly used markers of mTOR signaling. Transgenic mice expressing a rapamycin-resistant mutant of mTOR were also used to confirm the validity of these markers. The results demonstrated that mechanically-induced increases in p70(s6k T389 and 4E-BP1 S64 phosphorylation, and unexpectedly, a loss in total 4E-BP1, were fully mTOR-dependent signaling events. Furthermore, we determined that mechanical stimulation induced these mTOR-dependent events, and protein synthesis, through an ERK-independent mechanism. Similar to mechanical stimulation, exogenous PA also induced mTOR-dependent signaling via an ERK-independent mechanism. Moreover, PA was able to directly activate mTOR signaling in vitro. Combined, these results demonstrate that mechanical stimulation induces mTOR signaling, and protein synthesis, via an ERK-independent mechanism that potentially involves a direct interaction of PA with mTOR. Furthermore, it appears that a decrease in total 4E-BP1 may be part of the mTOR-dependent mechanism through which mechanical stimuli activate protein synthesis.

Mechanical properties of rock at high temperatures

International Nuclear Information System (INIS)

Kinoshita, Naoto; Abe, Tohru; Wakabayashi, Naruki; Ishida, Tsuyoshi.

1997-01-01

The laboratory tests have been performed in order to investigate the effects of temperature up to 300degC and pressure up to 30 MPa on the mechanical properties of three types of rocks, Inada granite, Sanjoume andesite and Oya tuff. The experimental results indicated that the significant differences in temperature dependence of mechanical properties exist between the three rocks, because of the difference of the factors which determine the mechanical properties of the rocks. The effect of temperature on the mechanical properties for the rocks is lower than that of pressure and water content. Temperature dependence of the mechanical properties is reduced by increase in pressure in the range of pressure and temperature investigated in this paper. (author)

Quantum Mechanics and Molecular Mechanics Study of the Catalytic Mechanism of Human AMSH-LP Domain Deubiquitinating Enzymes.

Science.gov (United States)

Zhu, Wenyou; Liu, Yongjun; Ling, Baoping

2015-08-25

Deubiquitinating enzymes (DUBs) catalyze the cleavage of the isopeptide bond in polyubiquitin chains to control and regulate the deubiquitination process in all known eukaryotic cells. The human AMSH-LP DUB domain specifically cleaves the isopeptide bonds in the Lys63-linked polyubiquitin chains. In this article, the catalytic mechanism of AMSH-LP has been studied using a combined quantum mechanics and molecular mechanics method. Two possible hydrolysis processes (Path 1 and Path 2) have been considered. Our calculation results reveal that the activation of Zn(2+)-coordinated water molecule is the essential step for the hydrolysis of isopeptide bond. In Path 1, the generated hydroxyl first attacks the carbonyl group of Gly76, and then the amino group of Lys63 is protonated, which is calculated to be the rate limiting step with an energy barrier of 13.1 kcal/mol. The energy barrier of the rate limiting step and the structures of intermediate and product are in agreement with the experimental results. In Path 2, the protonation of amino group of Lys63 is prior to the nucleophilic attack of activated hydroxyl. The two proton transfer processes in Path 2 correspond to comparable overall barriers (33.4 and 36.1 kcal/mol), which are very high for an enzymatic reaction. Thus, Path 2 can be ruled out. During the reaction, Glu292 acts as a proton transfer mediator, and Ser357 mainly plays a role in stabilizing the negative charge of Gly76. Besides acting as a Lewis acid, Zn(2+) also influences the reaction by coordinating to the reaction substrates (W1 and Gly76).

Transport cross sections based on a screened interaction potential: Comparison of classical and quantum-mechanical results

International Nuclear Information System (INIS)

Vincent, R.; Juaristi, J.I.; Nagy, I.

2005-01-01

Standard classical and quantum-mechanical methods are used to characterize the momentum-transfer cross section needed in energy-loss calculations and simulations for heavy, swift charges moving in an electron gas. By applying a well-known, finite-range screened Coulombic potential energy to model the two-body collision, the quantitative applicability range of the classical cross section is investigated as a function of charge (Z), screening length (R), and scattering relative velocity (v). The a posteriori condition (Z/R)/v 2 <1, as an upper bound for heavy charges, is deduced for this applicability range from the comparative study performed

Advances in Mechanisms Design : Proceedings of TMM 2012

CERN Document Server

Bílek, Martin; Hejnova, Monika; Zabka, Petr; Advances in Mechanisms Design

2012-01-01

The International Conference on the Theory of Machines and Mechanisms is organized every four years, under the auspices of the International Federation for the Promotion of Mechanism and Machine Science (IFToMM) and the Czech Society for Mechanics. This eleventh edition of the conference took place at the Technical University of Liberec, Czech Republic, 4-6 September 2012. This volume offers an international selection of the most important new results and developments, in 73 papers, grouped in seven different parts, representing a well-balanced overview, and spanning the general theory of machines and mechanisms, through analysis and synthesis of planar and spatial mechanisms, dynamics of machines and mechanisms, linkages and cams, computational mechanics, rotor dynamics, biomechanics, mechatronics, vibration and noise in machines, optimization of mechanisms and machines, control and monitoring systems of machines, accuracy and reliability of machines and mechanisms, robots and manipulators to the mechanisms ...

507 mechanical movements mechanisms and devices

CERN Document Server

Brown, Henry T

2005-01-01

Epicyclic trains, oblique rollers, trip hammers, and lazy-tongs are among the ingenious mechanisms defined and illustrated in this intriguing collection. Spanning the first century of the Industrial Revolution, this 1868 compilation features simplified, concise illustrations of the mechanisms used in hydraulics, steam engines, pneumatics, presses, horologes, and scores of other machines.The movements of each of the 507 mechanisms are depicted in drawings on the left-hand page, and the facing page presents a brief description of the item's use and operation. Ranging from simple to intricately c

Electro-chemo-mechanical response of a free-standing polypyrrole strip

Energy Technology Data Exchange (ETDEWEB)

Vazquez, G; Otero, T F; Cascales, J J L [Centra de ElectroquImica y Materiales Inteligentes (CEMI), Universidad Politecnica de Cartagena, Cartagena 30203, Murcia (Spain)], E-mail: javier.lopez@upct.es

2008-08-15

Further development of mechanical devices based on conducting polymers; require a precise understanding of their mechanical response, i.e. their control, under a controlled external current. In this work, we show some results for the relation between the electrical current consumed in the electrochemical process and the mechanical work developed by a freestanding polypyrrole strip, when it is subjected to a stretching force (stress). Under these conditions, from the results obtained in this work, we observe how it results almost impossible to predict a straight relationship between mechanical work and current consumed in the electrochemical process. In addition, we will quantify the variation of the mechanical properties of the free standing polypyrrole strip associated with the oxidation state of the polymer by measuring its Young's modulus.

Review of heavy ion reaction mechanisms

International Nuclear Information System (INIS)

Ngo, C.

1986-04-01

We review some of the many aspects of heavy-ion reaction mechanisms observed at bombarding energies smaller than approximately 50 MeV/u that is to say in what is called the low bombarding energy domain and the intermediate bombarding energy domain. We emphasize the results concerning the use of very heavy projectiles which has led to the observation of new mechanisms

Do different funding mechanisms produce different results? The implications of family planning for fiscal federalism.

Science.gov (United States)

McFarlane, D R; Meier, K J

1998-06-01

The 104th Congress considered massive structural changes in federal aid to the states. Not only would federal categorical grants be consolidated into block grants, but entitlement programs would be converted to block grants too. Using family planning as a case study, this article examines whether program impacts change if different grant mechanisms are employed. Findings from a pooled time series analysis of state family planning expenditures show that categorical funding (here, title X of the Public Health Service Act) is the most cost effective in producing desired outcomes, such as lowering infant mortality. Policies using entitlement grants are generally more cost effective than those that rely upon block grants. We discuss the implications of these findings for health policy more broadly and for fiscal federalism in general.

Supersymmetric symplectic quantum mechanics

Science.gov (United States)

de Menezes, Miralvo B.; Fernandes, M. C. B.; Martins, Maria das Graças R.; Santana, A. E.; Vianna, J. D. M.

2018-02-01

Symplectic Quantum Mechanics SQM considers a non-commutative algebra of functions on a phase space Γ and an associated Hilbert space HΓ to construct a unitary representation for the Galilei group. From this unitary representation the Schrödinger equation is rewritten in phase space variables and the Wigner function can be derived without the use of the Liouville-von Neumann equation. In this article we extend the methods of supersymmetric quantum mechanics SUSYQM to SQM. With the purpose of applications in quantum systems, the factorization method of the quantum mechanical formalism is then set within supersymmetric SQM. A hierarchy of simpler hamiltonians is generated leading to new computation tools for solving the eigenvalue problem in SQM. We illustrate the results by computing the states and spectra of the problem of a charged particle in a homogeneous magnetic field as well as the corresponding Wigner function.

Quantum Mechanics/Molecular Mechanics Modeling of Drug Metabolism

DEFF Research Database (Denmark)

Lonsdale, Richard; Fort, Rachel M; Rydberg, Patrik

2016-01-01

)-mexiletine in CYP1A2 with hybrid quantum mechanics/molecular mechanics (QM/MM) methods, providing a more detailed and realistic model. Multiple reaction barriers have been calculated at the QM(B3LYP-D)/MM(CHARMM27) level for the direct N-oxidation and H-abstraction/rebound mechanisms. Our calculated barriers......The mechanism of cytochrome P450(CYP)-catalyzed hydroxylation of primary amines is currently unclear and is relevant to drug metabolism; previous small model calculations have suggested two possible mechanisms: direct N-oxidation and H-abstraction/rebound. We have modeled the N-hydroxylation of (R...... indicate that the direct N-oxidation mechanism is preferred and proceeds via the doublet spin state of Compound I. Molecular dynamics simulations indicate that the presence of an ordered water molecule in the active site assists in the binding of mexiletine in the active site...

Mechanics and Physics of Precise Vacuum Mechanisms

CERN Document Server

Deulin, E. A; Panfilov, Yu V; Nevshupa, R. A

2010-01-01

In this book the Russian expertise in the field of the design of precise vacuum mechanics is summarized. A wide range of physical applications of mechanism design in electronic, optical-electronic, chemical, and aerospace industries is presented in a comprehensible way. Topics treated include the method of microparticles flow regulation and its determination in vacuum equipment and mechanisms of electronics; precise mechanisms of nanoscale precision based on magnetic and electric rheology; precise harmonic rotary and not-coaxial nut-screw linear motion vacuum feedthroughs with technical parameters considered the best in the world; elastically deformed vacuum motion feedthroughs without friction couples usage; the computer system of vacuum mechanisms failure predicting. This English edition incorporates a number of features which should improve its usefulness as a textbook without changing the basic organization or the general philosophy of presentation of the subject matter of the original Russian work. Exper...

May the Kyoto protocol produce results?

International Nuclear Information System (INIS)

Jaureguy-Naudin, M.

2009-01-01

A not well managed drastic reduction of greenhouse emissions might result in significant decrease of living standards, but without such reduction efforts, climate change might have five to twenty times higher costs. Thus, while indicating estimated consequences or evolutions of greenhouse emissions and temperature, the author stresses the need of emission reduction. She discusses the role of economic instruments which can be used in policies aimed at the struggle against climate change. She recalls the emission reduction commitments specified in the Kyoto protocol, discusses the present status, operation and results of the international emission trading scheme, the lessons learned after the first years of operation, comments the involvement of emerging countries in relationship with another mechanism defined in the protocol: the Clean Development Mechanism

Results of monitoring at Olkiluoto in 2006. Rock mechanics

International Nuclear Information System (INIS)

Mattila, J.

2007-07-01

Posiva Oy has operated a local microseismic at Olkiluto network since February 2002. During the monitoring in 2006, altogether 2041 events have been located in the Olkiluoto area, in the reported time period. The magnitudes of the observed events range from ML = -1.1 to 3.1 (ML = magnitude in local Richter's scale). Most of the events are construction-related explosions but two of them are recorded as microearthquakes. Evidence of seismic activity that would have influence on the safety of the ONKALO, have not been observed. The observed earthquakes that occurred in 2006 were small, with a magnitude of ML -0.6 and ML= -0.9. The earthquakes relate to small movements in brittle deformation zones OL-BFZ043 and OL-BFZ034. Estimated peak slip values of the earthquakes are 14 μm and 4 μm and the source radiuses 11 and 8 meters, respectively. The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. Since then, altogether 22 GPS measurement campaigns have been carried out at Olkiluoto. According to the time series of the GPS results, 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.22 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined (maximum velocity is -0.23 mm/a ± 0.023 mm/a) (orig.)

Investigation of mechanical properties and operative deformation mechanism in nano-crystalline Ni–Co/SiC electrodeposits

International Nuclear Information System (INIS)

Lari Baghal, S.M.; Amadeh, A.; Heydarzadeh Sohi, M.

2012-01-01

Highlights: ► The tensile properties of Ni–Co and Ni–Co/SiC deposits were investigated. ► The SiC particles enhanced tensile strength and ductility of nano-structured composites. ► The deformation mechanism at low and high strain rates were studied. - Abstract: Ni–Co/SiC nano-composites were prepared via electrodeposition from a modified Watts bath containing SiC particles with average particle size of 50 nm, SDS as surfactant and saccharin as grain refiner in appropriate amounts. The effect of nano-particle incorporation on microstructure, mechanical properties and deformation mechanism of electrodeposits were investigated. The mechanical properties of electrodeposits were investigated by Vickers microhardness and tensile tests. The results indicated that incorporation of SiC particles into a 15 nm Ni–Co matrix had no considerable effect on its microhardness and yield strength, that is, dispersion hardening did not operate in this range of grain size. However it was observed that co-deposition of uniform distributed SiC particles can significantly improve the ultimate tensile strength and elongation to failure of the deposits. Calculation of apparent activation volume from tensile test results at different strain rates proved that incorporation of SiC nano-particles are responsible for stress-assisted activation of GB atoms mechanism that can significantly increase the plasticity. Nano-crystalline Ni–Co matrix showed a mixed mod behavior of ductile and brittle fracture whereas incorporation of SiC particles and increasing the strain rate promoted ductile fracture mode.

Space Creation Mechanism during the Expansion of Universe

Directory of Open Access Journals (Sweden)

Emre Dil

2016-01-01

Full Text Available We propose a novel mechanism related to the expansion of universe. Recently Verlinde’s proposal has been applied to the deformed bosons being a candidate for the dark energy constituents, since the negative pressure of the deformed bosons. The expansion of universe is dependent on the dark energy and implies a creation of space; we admit that the space creation mechanism is related to the deformed bosons and so is the dark energy. In order to relate the dark energy and the mechanism for creation of space, we consider Verlinde’s proposal including the Holographic principle for emergence of space, which was recently applied to the deformed bosons. To check the validity of our mechanism, we calculate the ratio of the size of universe before and after the expansion and compare the results with the observational data. We find that the results are consistent with each other and infer that the proposed mechanism works correctly.

Investigation of Mechanical Properties and Interfacial Mechanics of Crystalline Nanomaterials

Science.gov (United States)

Qin, Qingquan

ultimate tensile strength were found to all increased as the NW diameter decreased. For the temperature effect study, a brief review on brittle-to-ductile transition (BDT) of silicon (Si) is presented. BDT temperature shows decreasing trend as size of the sample decrease. However, controversial results have been reported in terms of brittle or ductile behaviors for Si NWs at room temperature. A microelectromechanical systems (MEMS) thermal actuator (ETA) was designed to test NW without involving external heating. To circumvent undesired heating of the end effector, heat sink beams that can be co-fabricated with the thermal actuator were introduced. A combined modeling and experimental study was conducted to access the effect of such heat sink beams. Temperature distribution was measured and simulated using Raman scattering and multiphysics finite element method, respectively. Our results demonstrated that heat sink beams are effective in reducing the temperature of the thermal actuator. To get elevated temperature in a controllable fashion, a comb drive actuator was designed with separating actuation and heating mechanisms. Multiphysics finite element analysis (coupled electrical-thermal-mechanical) was used to optimize structure design and minimize undesired thermal loading/unloading. A Si NW with diameter of 50 nm was tested on the device under different temperatures. Stress strain curves at different temperatures revealed that plastic deformation occurs at temperature of 55 °C. For interfacial mechanics, we report an experimental study on the friction between Ag and ZnO NW tips (ends) and a gold substrate. An innovative experimental method based on column buckling theory was developed for the friction measurements. Direct measurements of the static friction force and interfacial shear strength between Si NWs and poly(dimethylsiloxane) (PDMS) is reported. The static friction and shear strength were found to increase rapidly and then decrease with the increasing

Hamiltonian mechanics limits microscopic engines

Science.gov (United States)

Anglin, James; Gilz, Lukas; Thesing, Eike

2015-05-01

We propose a definition of fully microscopic engines (micro-engines) in terms of pure mechanics, without reference to thermodynamics, equilibrium, or cycles imposed by external control, and without invoking ergodic theory. This definition is pragmatically based on the observation that what makes engines useful is energy transport across a large ratio of dynamical time scales. We then prove that classical and quantum mechanics set non-trivial limits-of different kinds-on how much of the energy that a micro-engine extracts from its fuel can be converted into work. Our results are not merely formal; they imply manageable design constraints on micro-engines. They also suggest the novel possibility that thermodynamics does not emerge from mechanics in macroscopic regimes, but rather represents the macroscopic limit of a generalized theory, valid on all scales, which governs the important phenomenon of energy transport across large time scale ratios. We propose experimental realizations of the dynamical mechanisms we identify, with trapped ions and in Bose-Einstein condensates (``motorized bright solitons'').

Mechanics of Failure Mechanisms in Structures

CERN Document Server

Carlson, R L; Craig, J I

2012-01-01

This book focuses on the mechanisms and underlying mechanics of failure in various classes of materials such as metallic, ceramic, polymeric, composite and bio-material.  Topics include tensile and compressive fracture, crack initiation and growth, fatigue and creep rupture in metallic materials, matrix cracking and delamination and environmental degradation in polymeric composites, failure of bio-materials such as prosthetic heart valves and prosthetic hip joints, failure of ceramics and ceramic matrix composites, failure of metallic matrix composites, static and dynamic buckling failure, dynamic excitations and creep buckling failure in structural systems. Chapters are devoted to failure mechanisms that are characteristic of each of the materials.  The work also provides the basic elements of fracture mechanics and studies in detail several niche topics such as the effects of toughness gradients, variable amplitude loading effects in fatigue, small fatigue cracks, and creep induced brittleness. Furthe...

A skeletal mechanism for biodiesel blend surrogates combustion

International Nuclear Information System (INIS)

An, H.; Yang, W.M.; Maghbouli, A.; Li, J.; Chua, K.J.

2014-01-01

Highlights: • A skeletal biodiesel reaction mechanism with 112 species was constructed. • The developed mechanism contains the CO, NO x and soot formation kinetics. • It was well validated against detailed reaction mechanism and experimental results. • The mechanism is suitable to simulate biodiesel, diesel and their blend fuels. - Abstract: A tri-component skeletal reaction mechanism consisting of methyl decanoate, methyl-9-decenoate, and n-heptane was developed for biodiesel combustion in diesel engine. It comprises 112 species participating in 498 reactions with the CO, NO x and soot formation mechanisms embedded. In this study, a detailed tri-component biodiesel mechanism was used as the start of mechanism reduction and the reduced mechanism was combined with a previously developed skeletal reaction mechanism for n-heptane to integrate the soot formation kinetics. A combined mechanism reduction strategy including the directed relation graph with error propagation and sensitivity analysis (DRGEPSA), peak concentration analysis, isomer lumping, unimportant reactions elimination and reaction rate adjustment methods was employed. The reduction process for biodiesel was performed over a range of initial conditions covering the pressures from 1 to 100 atm, equivalence ratios from 0.5 to 2.0 and temperatures from 700 to 1800 K, whereas for n-heptane, ignition delay predictions were compared against 17 shock tube experimental conditions. Extensive validations were performed for the developed skeletal reaction mechanism with 0-D ignition delay testing and 3-D engine simulations. The results indicated that the developed mechanism was able to accurately predict the ignition delay timings of n-heptane and biodiesel, and it could be integrated into 3-D engine simulations to predict the combustion characteristics of biodiesel. As such, the developed 112-species skeletal mechanism can accurately mimic the significant reaction pathways of the detailed reaction

Dynamics of ligand exchange mechanism at Cu(II) in water: an ab initio quantum mechanical charge field molecular dynamics study with extended quantum mechanical region.

Science.gov (United States)

Moin, Syed Tarique; Hofer, Thomas S; Weiss, Alexander K H; Rode, Bernd M

2013-07-07

Ab initio quantum mechanical charge field molecular dynamics (QMCF-MD) were successfully applied to Cu(II) embedded in water to elucidate structure and to understand dynamics of ligand exchange mechanism. From the simulation studies, it was found that using an extended large quantum mechanical region including two shells of hydration is required for a better description of the dynamics of exchanging water molecules. The structural features characterized by radial distribution function, angular distribution function and other analytical parameters were consistent with experimental data. The major outcome of this study was the dynamics of exchange mechanism and reactions in the first hydration shell that could not be studied so far. The dynamical data such as mean residence time of the first shell water molecules and other relevant data from the simulations are close to the results determined experimentally. Another major characteristic of hydrated Cu(II) is the Jahn-Teller distortion which was also successfully reproduced, leading to the final conclusion that the dominating aqua complex is a 6-coordinated species. The ab initio QMCF-MD formalism proved again its capabilities of unraveling even ambiguous properties of hydrated species that are far difficult to explore by any conventional quantum mechanics/molecular mechanics (QM/MM) approach or experiment.

Dynamics of ligand exchange mechanism at Cu(II) in water: An ab initio quantum mechanical charge field molecular dynamics study with extended quantum mechanical region

International Nuclear Information System (INIS)

Moin, Syed Tarique; Hofer, Thomas S.; Weiss, Alexander K. H.; Rode, Bernd M.

2013-01-01

Ab initio quantum mechanical charge field molecular dynamics (QMCF-MD) were successfully applied to Cu(II) embedded in water to elucidate structure and to understand dynamics of ligand exchange mechanism. From the simulation studies, it was found that using an extended large quantum mechanical region including two shells of hydration is required for a better description of the dynamics of exchanging water molecules. The structural features characterized by radial distribution function, angular distribution function and other analytical parameters were consistent with experimental data. The major outcome of this study was the dynamics of exchange mechanism and reactions in the first hydration shell that could not be studied so far. The dynamical data such as mean residence time of the first shell water molecules and other relevant data from the simulations are close to the results determined experimentally. Another major characteristic of hydrated Cu(II) is the Jahn-Teller distortion which was also successfully reproduced, leading to the final conclusion that the dominating aqua complex is a 6-coordinated species. The ab initio QMCF-MD formalism proved again its capabilities of unraveling even ambiguous properties of hydrated species that are far difficult to explore by any conventional quantum mechanics/molecular mechanics (QM/MM) approach or experiment

Development of Numerical Analysis Techniques Based on Damage Mechanics and Fracture Mechanics

International Nuclear Information System (INIS)

Chang, Yoon Suk; Lee, Dock Jin; Choi, Shin Beom; Kim, Sun Hye; Cho, Doo Ho; Lee, Hyun Boo

2010-04-01

The scatter of measured fracture toughness data and transferability problems among different crack configurations as well as geometry and loading conditions are major obstacles for application of fracture mechanics. To address these issues, recently, concerns on the local approach employing reliable micro-mechanical damage models are being increased again in connection with a progress of computational technology. In the present research, as part of development of fracture mechanical evaluation model for material degradation of reactor pressure boundary, several investigations on fracture behaviors were carried out. Especially, a numerical scheme to determine key parameters consisting both cleavage and ductile fracture estimate models was changed efficiently by incorporating a genetic algorithm. Also, with regard to the well-known master curve, newly reported methods such as bimodal master curve, randomly inhomogeneous master curve and single point estimation were reviewed to deal with homogeneous and inhomogeneous material characteristics. A series of preliminary finite element analyses was conducted to examine the element size effect on micro-mechanical models. Then, a new thickness correction equation was derived from parametric three-dimensional numerical simulations, which was founded on the current test standard, ASTM E1921, but could lead to get more realistic fracture toughness values. As a result, promising modified master curves as well as fracture toughness diagrams to convert data between pre-cracked V-notched and compact tension specimens were generated. Moreover, a user-subroutine in relation to GTN(Gurson-Tvergaard-Needleman) model was made by adopting Hill's 48 yield potential theory. By applying GTN model combined with the subroutine to small punch specimens, the effect of inhomogeneous properties on fracture behaviors of miniature specimens was confirmed. Therefore, it is anticipated that the aforementioned enhanced research results can be utilized

Thermo-mechanical interaction effects in foam cored sandwich panels-correlation between High-order models and Finite element analysis results

DEFF Research Database (Denmark)

Palleti, Hara Naga Krishna Teja; Santiuste, Carlos; Thomsen, Ole Thybo

2010-01-01

Thermo-mechanical interaction effects including thermal material degradation in polymer foam cored sandwich structures is investigated using the commercial Finite Element Analysis (FEA) package ABAQUS/Standard. Sandwich panels with different boundary conditions in the form of simply supported...

Morphing of the Dissipative Reaction Mechanism

International Nuclear Information System (INIS)

Schroeder, W.U.; Toke, J.; Gawlikowicz, W.; Houck, M.A.; Lu, J.; Pienkowski, L.

2003-01-01

Important trends in the evolution of heavy-ion reaction mechanisms with bombarding energy and impact parameter are reviewed. Essential features of dissipative reactions appear preserved at E/A = 50-62 MeV, such as dissipative orbiting and multi-nucleon exchange. The relaxation of the A/Z asymmetry with impact parameter is slow. Non-equilibrium emission of light particles and clusters is an important process accompanying the evolution of the mechanism. Evidence is presented for a new mechanism of statistical cluster emission from hot, metastable primary reaction products, driven by surface entropy. These results suggest a plausible reinterpretation of multi-fragmentation. (authors)

Morphing of the Dissipative Reaction Mechanism

Energy Technology Data Exchange (ETDEWEB)

Schroeder, W.U.; Toke, J.; Gawlikowicz, W.; Houck, M.A.; Lu, J.; Pienkowski, L. [Rochester Univ., Dept. of Chemistry, Rochester, NY (United States)

2003-07-01

Important trends in the evolution of heavy-ion reaction mechanisms with bombarding energy and impact parameter are reviewed. Essential features of dissipative reactions appear preserved at E/A = 50-62 MeV, such as dissipative orbiting and multi-nucleon exchange. The relaxation of the A/Z asymmetry with impact parameter is slow. Non-equilibrium emission of light particles and clusters is an important process accompanying the evolution of the mechanism. Evidence is presented for a new mechanism of statistical cluster emission from hot, metastable primary reaction products, driven by surface entropy. These results suggest a plausible reinterpretation of multi-fragmentation. (authors)

Characterization of porosity in support of mechanical property analysis

International Nuclear Information System (INIS)

Price, R.H.; Martin, R.J. III; Boyd, P.J.

1993-01-01

The general applicability of laboratory data for engineering purposes is a prime concern for the design and licensing of a potential repository of high level nuclear waste at Yucca Mountain. In order for the results of experiments to be applicable to the repository scale, the data must be scaled to in situ size and conditions. Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sampled test. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results

Selected mechanical properties of modified beech wood

Directory of Open Access Journals (Sweden)

Jiří Holan

2008-01-01

Full Text Available This thesis deals with an examination of mechanical properties of ammonia treated beach wood with a trademark Lignamon. For determination mechanical properties were used procedures especially based on ČSN. From the results is noticeable increased density of wood by 22% in comparison with untreated beach wood, which makes considerable increase of the most mechanical wood properties. Considering failure strength was raised by 32% and modulus of elasticity was raised at average about 46%.

Mechanical Integrity of Canisters Using a Fracture Mechanics Approach

Energy Technology Data Exchange (ETDEWEB)

Koyama, Tomofumi; Guoxiang Zhang; Lanru Jing [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Land and Water Resources Engineering

2006-07-15

This report presents the methods and results of a research project about numerical modeling of mechanical integrity of cast-iron canisters for the final disposal of spent nuclear fuel in Sweden, using combined boundary element (BEM) and finite element (FEM) methods. The objectives of the project are: 1) to investigate the possibility of initiation and growth of fractures in the cast-iron canisters under the mechanical loading conditions defined in the premises of canister design by Swedish Nuclear Fuel and Waste Management Co. (SKB); 2) to investigate the maximum bearing capacity of the cast iron canisters under uniformly distributed and gradually increasing boundary pressure until plastic failure. Achievement of the two objectives may provide some quantitative evidence for the mechanical integrity and overall safety of the cast-iron canisters that are needed for the final safety assessment of the geological repository of the radioactive waste repository in Sweden. The geometrical dimension, distribution and magnitudes of loads and Material properties of the canisters and possible fractures were provided by the latest investigations of SKB. The results of the BEM simulations, using the commercial code BEASY, indicate that under the currently defined loading conditions the possibility of initiation of new fractures or growth of existing fractures (defects) are very small, due to the reasons that: 1) the canisters are under mainly compressive stresses; 2) the induced tensile stress regions are too small in both dimension and magnitude to create new fractures or to induce growth of existing fractures, besides the fact that the toughness of the fractures in the cast iron canisters are much higher that the stress intensity factors in the fracture tips. The results of the FEM simulation show a approximately 75 MPa maximum pressure beyond which plastic collapse of the cast-iron canisters may occur, using an elastoplastic Material model. This figure is smaller compared

Mechanical and Tribological Characteristics of the AMC, Prepared by P/M Route along with Thermo-Mechanical Treatment

Science.gov (United States)

Mohapatra, Sambit Kumar; Maity, Kalipada; Bhuyan, Subrat Kumar; Prasad Satpathy, Mantra

2018-03-01

Thermo mechanical treatments have the ameliorated impacts on the mechanical and tribological properties of powder metallurgy components. In this investigation an aluminium matrix composite (AMC) {Al (92) + Mg (5) + Gr (1) + Ti (2)} has been prepared by following powder metallurgy technique, with double axial compaction and ulterior sintering. Secondary thermo-mechanical treatment i.e. hot extrusion through mathematical contoured cosine profiled die was considered. The die causes minimum velocity relative differences across the extrusion exit cross-section, which provides smooth material flow. Comparative result analysis for the mechanical and tribological characteristics of the specimen before and after extrusion was concentrated. Extrusion engenders significant amount of improvements of the properties those are attributed to excellent bond strength and uniform density distribution due to high compressive stress. Oxidative and delaminated wear mechanisms were found predominating type. To furnish the suitable explanation scanning electron microscopies have been performed for the wear surfaces.

Mechanical circulatory support in pediatrics.

Science.gov (United States)

Steffen, Robert J; Miletic, Kyle G; Schraufnagel, Dean P; Vargo, Patrick R; Fukamachi, Kiyotaka; Stewart, Robert D; Moazami, Nader

2016-05-01

End-stage heart failure affects thousands of children yearly and mechanical circulatory support is used at many points in their care. Extracorporeal membrane oxygenation supports both the failing heart and lungs, which has led to its use as an adjunct to cardiopulmonary resuscitation as well as in post-operative cardiogenic shock. Continuous-flow ventricular assist devices (VAD) have replaced pulsatile-flow devices in adults and early studies have shown promising results in children. The Berlin paracorporeal pulsatile VAD recently gained U.S. Food and Drug Administration approval and remains the only VAD approved in pediatrics. Failing univentricular hearts and other congenitally corrected lesions are new areas for mechanical support. Finding novel uses, improving durability, and minimizing complications are areas of growth in pediatric mechanical circulatory support.

A mechanically enhanced hybrid nano-stratified barrier with a defect suppression mechanism for highly reliable flexible OLEDs.

Science.gov (United States)

Jeong, Eun Gyo; Kwon, Seonil; Han, Jun Hee; Im, Hyeon-Gyun; Bae, Byeong-Soo; Choi, Kyung Cheol

2017-05-18

Understanding the mechanical behaviors of encapsulation barriers under bending stress is important when fabricating flexible organic light-emitting diodes (FOLEDs). The enhanced mechanical characteristics of a nano-stratified barrier were analyzed based on a defect suppression mechanism, and then experimentally demonstrated. Following the Griffith model, naturally-occurring cracks, which were caused by Zn etching at the interface of the nano-stratified structure, can curb the propagation of defects. Cross-section images after bending tests provided remarkable evidence to support the existence of a defect suppression mechanism. Many visible cracks were found in a single Al 2 O 3 layer, but not in the nano-stratified structure, due to the mechanism. The nano-stratified structure also enhanced the barrier's physical properties by changing the crystalline phase of ZnO. In addition, experimental results demonstrated the effect of the mechanism in various ways. The nano-stratified barrier maintained a low water vapor transmission rate after 1000 iterations of a 1 cm bending radius test. Using this mechanically enhanced hybrid nano-stratified barrier, FOLEDs were successfully encapsulated without losing mechanical or electrical performance. Finally, comparative lifetime measurements were conducted to determine reliability. After 2000 hours of constant current driving and 1000 iterations with a 1 cm bending radius, the FOLEDs retained 52.37% of their initial luminance, which is comparable to glass-lid encapsulation, with 55.96% retention. Herein, we report a mechanically enhanced encapsulation technology for FOLEDs using a nano-stratified structure with a defect suppression mechanism.

New mechanical chemical equilibrium in the copper-zinc alloys obtained by mechanical alloying

International Nuclear Information System (INIS)

Dianez, M.J; Criado, J.M; Donoso, E; Diaz, G

2006-01-01

A series of copper zinc alloys have been synthesized in the entire composition range Cu10Zn to Cu70Zn respectively, by mechanical alloying at room temperature in a planetary high-energy mill. A mechanism is proposed for the mechanical alloying reaction of the copper and zinc. It is made clear that the mechanical treatment considerably extends the range of composition of the α phase up to a content of 41% zinc, instead of the 36% accepted by the conventional phase diagrams. Exact determinations of the phase α reticular parameter were carried out as a function of its composition which can be used to determine the zinc content of the brass α. The results show that a brass phase α may be obtained containing 49% zinc in samples that include a mixture of phases α and β' after reaching stationary state as a function of the milling time. The stability field of phases β' and γ also displace noticeably higher values than those expected from the conventional binary Cu-Zn diagram. This behavior has been explained as a function of the nanometric texture generated by the milling (CW)

The Mechanical Metallurgy of Armour Steels

Science.gov (United States)

2016-10-01

plate hardness in Figure 2(a) are a result of increased resistance to plastic flow in a ductile hole formation failure mechanism. Beyond a certain...their mechanical metallurgy, and ballistic performance is explained, where such performance is primarily determined by material strength, hardness and...high strain rate behaviour. Other important topics such as toughness; the adiabatic shear phenomenon; structural cracking; and dual hardness and

Residential Mechanical Precooling

Energy Technology Data Exchange (ETDEWEB)

German, a. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Hoeschele, M. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

2014-12-01

This research conducted by the Alliance for Residential Building Innovation team evaluated mechanical air conditioner pre-cooling strategies in homes throughout the United States. EnergyPlus modeling evaluated two homes with different performance characteristics in seven climates. Results are applicable to new construction homes and most existing homes built in the last 10 years, as well as fairly efficient retrofitted homes.

Discrete mechanics

CERN Document Server

Caltagirone, Jean-Paul

2014-01-01

This book presents the fundamental principles of mechanics to re-establish the equations of Discrete Mechanics. It introduces physics and thermodynamics associated to the physical modeling.  The development and the complementarity of sciences lead to review today the old concepts that were the basis for the development of continuum mechanics. The differential geometry is used to review the conservation laws of mechanics. For instance, this formalism requires a different location of vector and scalar quantities in space. The equations of Discrete Mechanics form a system of equations where the H

Discrete mechanics

International Nuclear Information System (INIS)

Lee, T.D.

1985-01-01

This paper reviews the role of time throughout all phases of mechanics: classical mechanics, non-relativistic quantum mechanics, and relativistic quantum theory. As an example of the relativistic quantum field theory, the case of a massless scalar field interacting with an arbitrary external current is discussed. The comparison between the new discrete theory and the usual continuum formalism is presented. An example is given of a two-dimensional random lattice and its duel. The author notes that there is no evidence that the discrete mechanics is more appropriate than the usual continuum mechanics

Hybrid Gear Preliminary Results-Application of Composites to Dynamic Mechanical Components

Science.gov (United States)

Handschuh, Robert F.; Roberts Gary D.; Sinnamon, R.; Stringer, David B.; Dykas, Brian D.; Kohlman, Lee W.

2012-01-01

Composite spur gears were fabricated and then tested at NASA Glenn Research Center. The composite material served as the web of the gear between the gear teeth and a metallic hub for mounting to the torque-applying shaft. The composite web was bonded only to the inner and outer hexagonal features that were machined from an initially all-metallic aerospace quality spur gear. The Hybrid Gear was tested against an all-steel gear and against a mating Hybrid Gear. As a result of the composite to metal fabrication process used, the concentricity of the gears were reduced from their initial high-precision value. Regardless of the concentricity error, the hybrid gears operated successfully for over 300 million cycles at 10000 rpm and 490 in.*lbs torque. Although the design was not optimized for weight, the composite gears were found to be 20% lighter than the all-steel gears. Free vibration modes and vibration/noise tests were also conduct to compare the vibration and damping characteristic of the Hybrid Gear to all-steel gears. The initial results indicate that this type of hybrid design may have a dramatic effect on drive system weight without sacrificing strength.

Understanding the Catalytic Mechanism and the Nature of the Transition State of an Attractive Drug-Target Enzyme (Shikimate Kinase) by Quantum Mechanical/Molecular Mechanical (QM/MM) Studies.

Science.gov (United States)

Yao, Jianzhuang; Wang, Xia; Luo, Haixia; Gu, Pengfei

2017-11-16

Shikimate kinase (SK) is the fifth bacterial enzyme involved in the shikimate pathway for biosynthesis of life-indispensable components, such as aromatic amino acids. The absence of the shikimate pathway in humans makes SK an attractive target for the rational design of drugs aimed at pathogenesis bacteria, such as Mycobacterium tuberculosis and Helicobacter pylori. However, an effective inhibitor of SK (e.g., a transition-state analogue) is still not available on the market due, at least in part, to a lack of knowledge on the catalytic mechanism and the nature of the rate-limiting transition state. Herein, quantum mechanical/molecular mechanical (QM/MM) reaction coordinate, molecular dynamics (MD), and free-energy simulations have been performed to answer these questions. The results presented herein demonstrate that the phosphoryl-transfer process, which is the rate-limiting step of SK-catalyzed phosphorylation of shikimic acid (SKM), is a concerted one-step reaction proceeding through a loose transition state. The computational results agree well with those of experimental studies, specifically NMR results, X-ray crystal structure observation, and activation free-energy barrier. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural mechanics in nuclear power plant

International Nuclear Information System (INIS)

Han Liangbi

1998-01-01

The main research works in structural mechanics in reactor technology are emphatically introduced. It is completed by structural mechanics engineers at Shanghai Nuclear Research and Design Institute associated with the design and construction problems for Qinshan NPP Unit 1 and Pakistani CHASNUPP. About structural mechanics problem for the containment, the rock and soft soil two different bases are considered. For the later the interaction between soil and structure is carefully studied. About the structural mechanics problem for the equipment and pipings, the three dimensional stress and fracture analyses are studied. For the structural dynamics problem, including flow induced vibration, the response analyses under earthquake and loss coolant accident loadings are studied. For pipings, the leak before break technique has been emphatically introduced. A lot of mathematical models, the used computer codes, analytical calculations and experimental results are also introduced. This is a comprehensive description about structural mechanics problem in pressurized water reactor nuclear power plant

Mechanics of machinery

CERN Document Server

Mostafa, Mahmoud A

2012-01-01

MechanismsDefinitions Degrees of Freedom of Planar Mechanisms Four-Revolute-Pairs Chains Single-Slider Chain Double-Slider Mechanisms Mechanisms with Higher Pairs Compound Mechanisms Special Mechanisms Analytical Position Analysis of Mechanisms Velocities and AccelerationsAbsolute Plane Motion of a Particle Relative Motion Applications to Common Links Analysis of Mechanisms: Graphical Method Method of Instantaneous Centers for Determining the VelocitiesAnalytical Analysis CamsIntroduction Types of Cams Modes of Input/Output Motion Follower Configurations Classes of Cams Spur GearsIntroduction

Computational structural mechanics for engine structures

Science.gov (United States)

Chamis, C. C.

1989-01-01

The computational structural mechanics (CSM) program at Lewis encompasses: (1) fundamental aspects for formulating and solving structural mechanics problems, and (2) development of integrated software systems to computationally simulate the performance/durability/life of engine structures. It is structured to mainly supplement, complement, and whenever possible replace, costly experimental efforts which are unavoidable during engineering research and development programs. Specific objectives include: investigate unique advantages of parallel and multiprocesses for: reformulating/solving structural mechanics and formulating/solving multidisciplinary mechanics and develop integrated structural system computational simulators for: predicting structural performances, evaluating newly developed methods, and for identifying and prioritizing improved/missing methods needed. Herein the CSM program is summarized with emphasis on the Engine Structures Computational Simulator (ESCS). Typical results obtained using ESCS are described to illustrate its versatility.

Classical to quantum mechanical tunneling mechanism crossover in thermal transitions between magnetic states.

Science.gov (United States)

Vlasov, Sergei; Bessarab, Pavel F; Uzdin, Valery M; Jónsson, Hannes

2016-12-22

Transitions between states of a magnetic system can occur by jumps over an energy barrier or by quantum mechanical tunneling through the energy barrier. The rate of such transitions is an important consideration when the stability of magnetic states is assessed for example for nanoscale candidates for data storage devices. The shift in transition mechanism from jumps to tunneling as the temperature is lowered is analyzed and a general expression derived for the crossover temperature. The jump rate is evaluated using a harmonic approximation to transition state theory. First, the minimum energy path for the transition is found with the geodesic nudged elastic band method. The activation energy for the jumps is obtained from the maximum along the path, a saddle point on the energy surface, and the eigenvalues of the Hessian matrix at that point as well as at the initial state minimum used to estimate the entropic pre-exponential factor. The crossover temperature for quantum mechanical tunneling is evaluated from the second derivatives of the energy with respect to orientation of the spin vector at the saddle point. The resulting expression is applied to test problems where analytical results have previously been derived, namely uniaxial and biaxial spin systems with two-fold anisotropy. The effect of adding four-fold anisotropy on the crossover temperature is demonstrated. Calculations of the jump rate and crossover temperature for tunneling are also made for a molecular magnet containing an Mn 4 group. The results are in excellent agreement with previously reported experimental measurements on this system.

Teaching Continuum Mechanics in a Mechanical Engineering Program

Science.gov (United States)

Liu, Yucheng

2011-01-01

This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

The Clinical Utilisation of Respiratory Elastance Software (CURE Soft): a bedside software for real-time respiratory mechanics monitoring and mechanical ventilation management.

Science.gov (United States)

Szlavecz, Akos; Chiew, Yeong Shiong; Redmond, Daniel; Beatson, Alex; Glassenbury, Daniel; Corbett, Simon; Major, Vincent; Pretty, Christopher; Shaw, Geoffrey M; Benyo, Balazs; Desaive, Thomas; Chase, J Geoffrey

2014-09-30

Real-time patient respiratory mechanics estimation can be used to guide mechanical ventilation settings, particularly, positive end-expiratory pressure (PEEP). This work presents a software, Clinical Utilisation of Respiratory Elastance (CURE Soft), using a time-varying respiratory elastance model to offer this ability to aid in mechanical ventilation treatment. CURE Soft is a desktop application developed in JAVA. It has two modes of operation, 1) Online real-time monitoring decision support and, 2) Offline for user education purposes, auditing, or reviewing patient care. The CURE Soft has been tested in mechanically ventilated patients with respiratory failure. The clinical protocol, software testing and use of the data were approved by the New Zealand Southern Regional Ethics Committee. Using CURE Soft, patient's respiratory mechanics response to treatment and clinical protocol were monitored. Results showed that the patient's respiratory elastance (Stiffness) changed with the use of muscle relaxants, and responded differently to ventilator settings. This information can be used to guide mechanical ventilation therapy and titrate optimal ventilator PEEP. CURE Soft enables real-time calculation of model-based respiratory mechanics for mechanically ventilated patients. Results showed that the system is able to provide detailed, previously unavailable information on patient-specific respiratory mechanics and response to therapy in real-time. The additional insight available to clinicians provides the potential for improved decision-making, and thus improved patient care and outcomes.

Supersymmetric quantum mechanics on n-dimensional manifolds

International Nuclear Information System (INIS)

O'Connor, M.

1990-01-01

In this thesis the author investigates the properties of the supersymmetric path integral on Riemannian manifolds. Chapter 1 is a brief introduction to supersymmetric path integral can be defined as the continuum limit of a discrete supersymmetric path integral. In Chapter 3 he shows that point canonical transformations in the path integral for ordinary quantum mechanics can be performed naively provided one uses the supersymmetric path integral. Chapter 4 generalizes the results of chapter 3 to include the propagation of all the fermion sectors in supersymmetric quantum mechanics. In Chapter 5 he shows how the properties of supersymmetric quantum mechanics can be used to investigate topological quantum mechanics

HFCVD Diamond-Coated Mechanical Seals

Directory of Open Access Journals (Sweden)

Raul Simões

2018-05-01

Full Text Available A mechanical seal promotes the connection between systems or mechanisms, preventing the escape of fluids to the exterior. Nonetheless, due to extreme working conditions, premature failure can occur. Diamond, due to its excellent properties, is heralded as an excellent choice to cover the surface of these devices and extend their lifetime. Therefore, the main objective of this work was to deposit diamond films over mechanical seals and test the coated seals on a water pump, under real working conditions. The coatings were created by hot filament chemical vapor deposition (HFCVD and two consecutive layers of micro- and nanocrystalline diamond were deposited. One of the main difficulties is the attainment of a good adhesion between the diamond films and the mechanical seal material (WC-Co. Nucleation, deposition conditions, and pre-treatments were studied to enhance the coating. Superficial wear or delamination of the film was investigated using SEM and Raman characterization techniques, in order to draw conclusions about the feasibility of these coatings in the WC-Co mechanical seals with the purpose of increasing their performance and life time. The results obtained gave a good indication about the feasibility of this process and the deposition conditions used, with the mechanical seals showing no wear and no film delamination after a real work environment test.

Design and Experimental Investigation of Pneumatic Movement Mechanism Supported by Mechanic Cam and Crank Shaft

Directory of Open Access Journals (Sweden)

Salih KORUCU

2015-02-01

Full Text Available The pressurized air is applied to many sectors required purity and velocity. One of these sectors is to use of air as impulsive force in the moving mechanisms. In this study, the movement mechanism prototype worked with compressed air was designed and produced forlight vehicle engine as motorbike and ATV (All-Terrain Vehicle. In developed mechanisms, pneumatic artificial muscles were used for a given movement of crankshaft. A cam system was also designed for synchronization pneumatic muscles. In this way, these muscles transmit the synchronous movement to crankshaft. At the end of the study, the developed mechanism was mounted on an ATV vehicle(110 cc/ Cubic Centimeter, engine displacement capacityand its performance was tested using the four different weights (50, 75, 100 and 150 kg, three different pressures (4, 5 and 6 bar and two different hoses (Ø 6 and Ø 8 mm. By considering experimental results and design criteria, power of the movement mechanism was obtained as 886 Watt. With this study, minimization of energy consumption for movement of passenger cars, and using clean and cheap energy as ATV which can be alternative for single or two passenger vehicles.

Mechanisms of multidrug transporters

NARCIS (Netherlands)

Bolhuis, H; van Veen, H.W.; Poolman, B.; Driessen, A.J.M.; Konings, W.N

Drug resistance, mediated by various mechanisms, plays a crucial role in the failure of the drug-based treatment of various infectious diseases. As a result, these infectious diseases re-emerge rapidly and cause many victims every year. Another serious threat is imposed by the development of

Influence of Compatibilizer and Processing Conditions on Morphology, Mechanical Properties, and Deformation Mechanism of PP/Clay Nano composite

International Nuclear Information System (INIS)

Akbari, B.; Bagheri, R.

2012-01-01

Polypropylene/montmorillonite nano composite was prepared by melt intercalation method using a twin-screw extruder with starve feeding system in this paper. The effects of compatibilizer, extruder rotor speed and feeding rate on properties of nano composite were investigated. Structure, tensile, and impact properties and deformation mechanism of the compounds were studied. For investigation of structure and deformation mechanisms, X-ray diffraction (XRD) and transmission optical microscopy (TOM) techniques were utilized, respectively. The results illustrate that introduction of the compatibilizer and also variation of the processing conditions affect structure and mechanical properties of nano composite.

Mechanical design

CERN Document Server

Risitano, Antonino

2011-01-01

METHODOLOGICAL STATEMENT OF ENGINEERING DESIGNApproaches to product design and developmentMechanical design and environmental requirementsPROPERTIES OF ENGINEERING MATERIALSMaterials for mechanical designCharacterization of metalsStress conditionsFatigue of materialsOptimum material selection in mechanical designDESIGN OF MECHANICAL COMPONENTS AND SYSTEMSFailure theoriesHertz theoryLubrificationShafts and bearingsSplines and keysSpringsFlexible machine elementsSpur gearsPress and shrink fitsPressure tubesCouplingsClutchesBrakes

QUANTUM MECHANICS. Quantum squeezing of motion in a mechanical resonator.

Science.gov (United States)

Wollman, E E; Lei, C U; Weinstein, A J; Suh, J; Kronwald, A; Marquardt, F; Clerk, A A; Schwab, K C

2015-08-28

According to quantum mechanics, a harmonic oscillator can never be completely at rest. Even in the ground state, its position will always have fluctuations, called the zero-point motion. Although the zero-point fluctuations are unavoidable, they can be manipulated. Using microwave frequency radiation pressure, we have manipulated the thermal fluctuations of a micrometer-scale mechanical resonator to produce a stationary quadrature-squeezed state with a minimum variance of 0.80 times that of the ground state. We also performed phase-sensitive, back-action evading measurements of a thermal state squeezed to 1.09 times the zero-point level. Our results are relevant to the quantum engineering of states of matter at large length scales, the study of decoherence of large quantum systems, and for the realization of ultrasensitive sensing of force and motion. Copyright © 2015, American Association for the Advancement of Science.

Atomistic modeling of mechanical properties of polycrystalline graphene.

Science.gov (United States)

Mortazavi, Bohayra; Cuniberti, Gianaurelio

2014-05-30

We performed molecular dynamics (MD) simulations to investigate the mechanical properties of polycrystalline graphene. By constructing molecular models of ultra-fine-grained graphene structures, we studied the effect of different grain sizes of 1-10 nm on the mechanical response of graphene. We found that the elastic modulus and tensile strength of polycrystalline graphene decrease with decreasing grain size. The calculated mechanical proprieties for pristine and polycrystalline graphene sheets are found to be in agreement with experimental results in the literature. Our MD results suggest that the ultra-fine-grained graphene structures can show ultrahigh tensile strength and elastic modulus values that are very close to those of pristine graphene sheets.

Incidence of shoulder and neck pain in a working population: effect modification between mechanical and psychosocial exposures at work? Results from a one year follow up of the Malmö shoulder and neck study cohort.

Science.gov (United States)

Ostergren, Per-Olof; Hanson, Bertil S; Balogh, Istvan; Ektor-Andersen, John; Isacsson, Agneta; Orbaek, Palle; Winkel, Jörgen; Isacsson, Sven-Olof

2005-09-01

To assess the impact of mechanical exposure and work related psychosocial factors on shoulder and neck pain. A prospective cohort study. 4919 randomly chosen, vocationally active men and women ages 45-65 residing in a Swedish city. Neck and shoulder pain were determined by the standardised Nordic questionnaire. Mechanical exposure was assessed by an index based on 11 items designed and evaluated for shoulder and neck disorders. Work related psychosocial factors were measured by the Karasek and Theorell demand-control instrument. High mechanical exposure was associated with heightened risk for shoulder and neck pain among men and women during follow up. Age adjusted odds ratios (OR) were 2.17 (95% confidence intervals (CI): 1.65, 2.85) and 1.59 (95% CI: 1.22, 2.06), respectively. In women, job strain (high psychological job demands and low job decision latitude) correlated with heightened risk (OR = 1.73, 95% CI: 1.29, 2.31). These risk estimates remained statistically significant when controlled for high mechanical exposure regarding job strain (and vice versa), and for sociodemographic factors. Testing for effect modification between high mechanical exposure and job strain showed them acting synergistically only in women. Job related mechanical exposure in both sexes, and psychosocial factors in women, seem independently of each other to play a part for development of shoulder and neck pain in vocationally active people. The effect of psychosocial factors was more prominent in women, which could be the result of biological factors as well as gender issues. These results suggest that interventions aiming at reducing the occurrence of shoulder and neck pain should include both mechanical and psychosocial factors.

Experimental Analysis of Tensile Mechanical Properties of Sprayed FRP

Directory of Open Access Journals (Sweden)

Zhao Yang

2016-01-01

Full Text Available To study the tensile mechanical properties of sprayed FRP, 13 groups of specimens were tested through uniaxial tensile experiments, being analyzed about stress-strain curve, tensile strength, elastic modulus, breaking elongation, and other mechanical properties. Influencing factors on tensile mechanical properties of sprayed FRP such as fiber type, resin type, fiber volume ratio, fiber length, and composite thickness were studied in the paper too. The results show that both fiber type and resin type have an obvious influence on tensile mechanical properties of sprayed FRP. There will be a specific fiber volume ratio for sprayed FRP to obtain the best tensile mechanical property. The increase of fiber length can lead to better tensile performance, while that of composite thickness results in property degradation. The study can provide reference to popularization and application of sprayed FRP material used in structure reinforcement.

Mechanical disruption of tumors by iron particles and magnetic field application results in increased anti-tumor immune responses.

Directory of Open Access Journals (Sweden)

Myriam N Bouchlaka

Full Text Available The primary tumor represents a potential source of antigens for priming immune responses for disseminated disease. Current means of debulking tumors involves the use of cytoreductive conditioning that impairs immune cells or removal by surgery. We hypothesized that activation of the immune system could occur through the localized release of tumor antigens and induction of tumor death due to physical disruption of tumor architecture and destruction of the primary tumor in situ. This was accomplished by intratumor injection of magneto-rheological fluid (MRF consisting of iron microparticles, in Balb/c mice bearing orthotopic 4T1 breast cancer, followed by local application of a magnetic field resulting in immediate coalescence of the particles, tumor cell death, slower growth of primary tumors as well as decreased tumor progression in distant sites and metastatic spread. This treatment was associated with increased activation of DCs in the draining lymph nodes and recruitment of both DCs and CD8(+T cells to the tumor. The particles remained within the tumor and no toxicities were observed. The immune induction observed was significantly greater compared to cryoablation. Further anti-tumor effects were observed when MRF/magnet therapy was combined with systemic low dose immunotherapy. Thus, mechanical disruption of the primary tumor with MRF/magnetic field application represents a novel means to induce systemic immune activation in cancer.

Quantum mechanics from general relativity

International Nuclear Information System (INIS)

Sachs, M.

1986-01-01

A generalization of quantum mechanics is demonstrated in the context of general relativity, following from a generally covariant field theory of inertia. Nonrelativistically, the formalism corresponds with linear quantum mechanics. In the limit of special relativity, nonlinearity remains and several new features are derived: (1) Particle-antiparticle pairs do not annihilate; an exact bound state solution is derived corresponding with all experimental facts about annihilation/creation - which, in approximation, gives the blackbody radiation spectrum for a sea of such pairs. (2) A result is proven, without approximation, that is physically equivalent to the Pauli exclusion principle - which, in linear approximation, gives the totally antisymmetrised many-body wave function and Fermi-Dirac statistics. (3) The hydrogen spectrum is derived, including the Lamb shifts, in agreement with experiment; new results are found for high energy electron-proton scattering. (4) Finally, several applications to the elementary particle domain are demonstrated, in agreement with results from experimental high energy physics. (Auth.)

COPING MECHANISM OF CAREER WOMEN WITH BREAST CANCER

Directory of Open Access Journals (Sweden)

Rosnani Rosnani

2017-06-01

Full Text Available Introduction: Patients with cancer may experience psychological disorders such as depression, anxiety, anger, helplessness, and unappreciated, so in certain situations require defense mechanisms (coping mechanism to oppose or resist feelings of anxiety, fear or stress that haunt her. The aim of this study was to know the coping mechanism of career women with breast cancer reviewed by phenomenology in Palembang 2016. Method: Type of this study was a qualitative study with a phenomenological approach. Total samples were 8 participants with inclusion criteria: career women, productive age range, health physic and physiologic. Independent variable was a coping mechanism, and the dependent variable was breast cancer. The instrument used the voice recorder, and interview guides. Data analyze used verbatim transcript with credibility, dependability, and confirmability. Result: The results showed that working women who have breast cancer have a coping strategy that is adjusted to the psychological condition and physical reactions of the therapy in progress. Psychologically, the coping mechanism is in the form of rejecting, drawing closer to Allah SWT, seeking the opinion of other health workers, discussing conditions with spouse and family, seeking alternative treatment and asking for doctor's direction. The coping mechanism of the body's reaction to therapy is done by taking medicine according to the rules and remember Allah SWT. Conclusions: Need the support of the coping mechanism in patients with breast cancer and nursing care approach with the pattern of coping mechanisms with the involvement of the family.

The Antikythera mechanism and the mechanical universe

Science.gov (United States)

Edmunds, M. G.

2014-10-01

How did our view of the Universe develop? By the mid-eighteenth century, a world view had developed of a system constrained by physical laws. These laws, if not entirely understood, showed regularity and could be handled mathematically to provide both explanation and prediction of celestial phenomena. Most of us have at least some hazy idea of the fundamental shift that came through the work of Copernicus, Kepler, Galileo and Newton. The idea of a 'Mechanical Universe' running rather like a clock tends to be associated with these sixteenth- and seventeenth-century pioneers. It remains a useful - and perhaps comforting - analogy. Yet, recent investigations based around the Antikythera Mechanism, an artefact from ancient Greece, reinforce a view that the 'Mechanical' conception has been around for a much longer time - indeed certainly as far back as the third century BC. The extent of mechanical design expertise existing around 100 BC as witnessed by the Antikythera Mechanism comes as a great surprise to most people. It is certainly a very ingenious device, often referred to as 'The World's First Computer' although it is really a sophisticated mechanical astronomical calculator with its functions pre-determined rather than programmable. In this review, the structure and functions of the Antikythera Mechanism are described. The astronomy, cosmology and technology inherent in the machine fit surprisingly well into the context of its contemporary Classical world. A strong claim will be made for the influence of such mechanisms on the development of astronomical and philosophical views, based on literary reference. There is evidence that the technology persisted until its spectacular and rather sudden re-appearance in Western Europe around 1300 AD. From then on it is not hard to chart a path through the astronomical clocks of the sixteenth century to Kepler's aim (expressed in a 1605 letter) to 'show that the heavenly machine is not a kind of divine, live being, but a

THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

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V. V. Trandafilov

2016-06-01

Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed.

THE STIRLING GAS REFRIGERATING MACHINE MECHANICAL DESIGN IMPROVING

Directory of Open Access Journals (Sweden)

V. V. Trandafilov

2016-02-01

Full Text Available To improve the mechanical design of the piston Stirling gas refrigeration machine the structural optimization of rotary vane Stirling gas refrigeration machine is carried out. This paper presents the results of theoretical research. Analysis and prospects of rotary vane Stirling gas refrigeration machine for domestic and industrial refrigeration purpose are represented. The results of a patent search by mechanisms of transformation of rotary vane machines are discussed

Enhancement of mechanical properties of 123 superconductors

Science.gov (United States)

Balachandran, Uthamalingam

1995-01-01

A composition and method of preparing YBa.sub.2 Cu.sub.3 O.sub.7-x superconductor. Addition of tin oxide containing compounds to YBCO superconductors results in substantial improvement of fracture toughness and other mechanical properties without affect on T.sub.c. About 5-20% additions give rise to substantially improved mechanical properties.

Controlling chaos based on an adaptive adjustment mechanism

International Nuclear Information System (INIS)

Zheng Yongai

2006-01-01

In this paper, we extend the ideas and techniques developed by Huang [Huang W. Stabilizing nonlinear dynamical systems by an adaptive adjustment mechanism. Phys Rev E 2000;61:R1012-5] for controlling discrete-time chaotic system using adaptive adjustment mechanism to continuous-time chaotic system. Two control approaches, namely adaptive adjustment mechanism (AAM) and modified adaptive adjustment mechanism (MAAM), are investigated. In both case sufficient conditions for the stabilization of chaotic systems are given analytically. The simulation results on Chen chaotic system have verified the effectiveness of the proposed techniques

Focal degeneration of basal cells and the resultant auto-immunoreactions: a novel mechanism for prostate tumor progression and invasion.

Science.gov (United States)

Man, Yan-Gao; Gardner, William A

2008-01-01

The development of human prostate cancer is believed to be a multistep process, progressing sequentially from normal, to hyperplasia, to prostatic intraepithelial neoplasia (PIN), and to invasive and metastatic lesions. High grade PIN has been generally considered as the direct precursor of invasive lesions, and the progression of PIN is believed to be triggered primarily, if not solely, by the overproduction of proteolytic enzymes predominately by cancer cells, which result in the degradation of the basement membrane. These theories, however, are hard to reconcile with two main facts: (1) only about 30% untreated PIN progress to invasive stage, while none of the current approaches could accurately identify the specific PIN or individuals at greater risk for progression, and (2) results from recent world-wide clinical trials with a wide variety of proteolytic enzyme inhibitors have been very disappointing, casting doubt on the validity of the proteolytic enzyme theory. Since over 90% of prostate cancer-related deaths result from invasion-related illness and the incidence of PIN could be up to 16.5-25% in routine or ultrasound guided prostate biopsy, there is an urgent need to uncover the intrinsic mechanism of prostate tumor invasion. Promoted by the facts that the basal cell population is the source of several tumor suppressors and the absence of the basal cell layer is the most distinct feature of invasive lesions, our recent studies have intended to identify the early alterations of basal cell layers and their impact on tumor invasion using multidisciplinary approaches. Our studies revealed that a subset of pre-invasive tumors contained focal disruptions (the absence of basal cells resulting in a gap greater than the combined size of at least three epithelial cells) in surrounding basal cell layers. Compared to their non-disrupted counterparts, focally disrupted basal cell layers had several unique features: (1) significantly lower proliferation; (2

Recent trials to verify quantum mechanics

International Nuclear Information System (INIS)

Paty, M.

1974-01-01

An account of the experiments which deal with the verification of Quantum Mechanics and the hidden variable problem is made. First, the well-known EPR paradox is recalled which, in spite of its refutation by Bohr, was the starting point of the questionning on the completeness of Quantum Mechanics and of hidden variable theories; and then Bell's theorem, which shows that the two approaches, Quantum Mechanics and hidden variables, can be put in contradiction. Thereafter the various types of experiments which have been carried out on that subject, mostly concerning the correlation measurements between two photons emitted by a quantum system are described. The most recent experimental results are diverging, some of them to confirm and some others to contradict quantum mechanics. A review of these is given; and a discussion is presented about their possible implications [fr

Semiclassical statistical mechanics

International Nuclear Information System (INIS)

Stratt, R.M.

1979-04-01

On the basis of an approach devised by Miller, a formalism is developed which allows the nonperturbative incorporation of quantum effects into equilibrium classical statistical mechanics. The resulting expressions bear a close similarity to classical phase space integrals and, therefore, are easily molded into forms suitable for examining a wide variety of problems. As a demonstration of this, three such problems are briefly considered: the simple harmonic oscillator, the vibrational state distribution of HCl, and the density-independent radial distribution function of He 4 . A more detailed study is then made of two more general applications involving the statistical mechanics of nonanalytic potentials and of fluids. The former, which is a particularly difficult problem for perturbative schemes, is treated with only limited success by restricting phase space and by adding an effective potential. The problem of fluids, however, is readily found to yield to a semiclassical pairwise interaction approximation, which in turn permits any classical many-body model to be expressed in a convenient form. The remainder of the discussion concentrates on some ramifications of having a phase space version of quantum mechanics. To test the breadth of the formulation, the task of constructing quantal ensemble averages of phase space functions is undertaken, and in the process several limitations of the formalism are revealed. A rather different approach is also pursued. The concept of quantum mechanical ergodicity is examined through the use of numerically evaluated eigenstates of the Barbanis potential, and the existence of this quantal ergodicity - normally associated with classical phase space - is verified. 21 figures, 4 tables

Mechanical engineers' handbook, materials and engineering mechanics

CERN Document Server

Kutz, Myer

2015-01-01

Full coverage of materials and mechanical design inengineering Mechanical Engineers' Handbook, Fourth Edition provides aquick guide to specialized areas you may encounter in your work,giving you access to the basics of each and pointing you towardtrusted resources for further reading, if needed. The accessibleinformation inside offers discussions, examples, and analyses ofthe topics covered. This first volume covers materials and mechanical design, givingyou accessible and in-depth access to the most common topics you'llencounter in the discipline: carbon and alloy steels, stainlesssteels, a

Quantum mechanics from classical statistics

International Nuclear Information System (INIS)

Wetterich, C.

2010-01-01

Quantum mechanics can emerge from classical statistics. A typical quantum system describes an isolated subsystem of a classical statistical ensemble with infinitely many classical states. The state of this subsystem can be characterized by only a few probabilistic observables. Their expectation values define a density matrix if they obey a 'purity constraint'. Then all the usual laws of quantum mechanics follow, including Heisenberg's uncertainty relation, entanglement and a violation of Bell's inequalities. No concepts beyond classical statistics are needed for quantum physics - the differences are only apparent and result from the particularities of those classical statistical systems which admit a quantum mechanical description. Born's rule for quantum mechanical probabilities follows from the probability concept for a classical statistical ensemble. In particular, we show how the non-commuting properties of quantum operators are associated to the use of conditional probabilities within the classical system, and how a unitary time evolution reflects the isolation of the subsystem. As an illustration, we discuss a classical statistical implementation of a quantum computer.

Mechanism and prediction of burnout

International Nuclear Information System (INIS)

Hewitt, G.F.

1977-01-01

The lecture begins by discussing the definitions of burnout and the various parametric effects as seen from the results for burnout measurements in uniformly heated round tubes. The correlations which are developed from these measurements and their applications to the case of non-uniform axial distribution of heat flux is then discussed in general terms as an illustration of the importance of knowing more about the nature and mechanism of the burnout. The next section of the lecture is concerned with summarizing broadly the various possible mechanisms in both the sub-cooled region and the quality region. It transpires that, for tubes of reasonable length, the normal first occurrence of burnout is in the annular flow regime. A discussion of burnout mechanisms in this regime then follows, with descriptions of the various experimental techniques evolved to study the mechanism. The final section of the lecture is concerned with prediction methods for burnout in annular flow and the application of these methods to prediction of burnout in round tubes, annuli and rod bundles, with a variety of fluids

Mechanical properties of cork under contact stresses

International Nuclear Information System (INIS)

Parralejo, A. D.; Guiberteau, F.; Fortes, M. A.; Rosa, M. E.

2001-01-01

In this work our interest is focussed on the mechanical behaviour of natural cork under contact stresses. Many of the applications of this curious material are related with its mechanical response under such a stress field, however this topic has not been still sufficiently considered in the scientific literature. For this purpose, we proposed the use of Hertzian indentation tests. By using this mythology we have investigated the cork structure influence on the corresponding mechanical properties. Our results reveal a clear mechanical anisotropy effect. Moreover, the elastic modulus corresponding to specific directions have been estimated. Several are the main advantages of this specific test mythology versus traditional uniaxial compression tests, specially simplicity and local character. (Author) 9 refs

Energy transfer in a mechanically trapped exciplex.

Science.gov (United States)

Klosterman, Jeremy K; Iwamura, Munetaka; Tahara, Tahei; Fujita, Makoto

2009-07-15

Host-guest complexes involving M(6)L(4) coordination cages can display unusual photoreactivity, and enclathration of the very large fluorophore bisanthracene resulted in an emissive, mechanically trapped intramolecular exciplex. Mechanically linked intramolecular exciplexes are important for understanding the dependence of energy transfer on donor-acceptor distance, orientation, and electronic coupling but are relatively unexplored. Steady-state and picosecond time-resolved fluorescence measurements have revealed that selective excitation of the encapsulated guest fluorophore results in efficient energy transfer from the excited guest to an emissive host-guest exciplex state.

A mechanical characterisation on multiple timescales of electroconductive magnetorheological elastomers

Science.gov (United States)

Schümann, M.; Morich, J.; Kaufhold, T.; Böhm, V.; Zimmermann, K.; Odenbach, S.

2018-05-01

Magnetorheological elastomers are a type of smart hybrid material which combines elastic properties of a soft elastomer matrix with magnetic properties of magnetic micro particles. This leads to a material with magnetically controllable mechanical properties of which the magnetorheological effect is the best known. The addition of electroconductive particles to the polymer mix adds electrical properties to the material behaviour. The resulting electrical resistance of the sample can be manipulated by external magnetic fields and mechanical loads. This results in a distinct interplay of mechanical, electrical and magnetic effects with a highly complex time behaviour. In this paper a mechanical characterisation on multiple time scales was conducted to get an insight on the short and long-term electrical and mechanical behaviour of this novel material. The results show a complex resistivity behaviour on several timescales, sensitive to magnetic fields and strain velocity. The observed material exhibits fatigue and relaxation behaviour, whereas the magnetorheological effect appears not to interfere with the piezoresistive properties.

Enhancement of mechanical properties of 123 superconductors

Science.gov (United States)

Balachandran, U.

1995-04-25

A composition and method are disclosed of preparing YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} superconductor. Addition of tin oxide containing compounds to YBCO superconductors results in substantial improvement of fracture toughness and other mechanical properties without affect on T{sub c}. About 5-20% additions give rise to substantially improved mechanical properties.

Shaking table testing of mechanical components

International Nuclear Information System (INIS)

Jurukovski, D.; Taskov, Lj.; Mamucevski, D.; Petrovski, D.

1995-01-01

Presented is the experience of the Institute of Earthquake Engineering and Engineering Seismology, Skopje, Republic of Macedonia in seismic qualification of mechanical components by shaking table testing. Technical data and characteristics for the three shaking tables available at the Institute are given. Also, for characteristic mechanical components tested at the Institute laboratories, basic data such as producer, testing investor, description of the component, testing regulation, testing equipment and final user of the results. (author)

Mechanical performance of styrene-butadiene-rubber filled with carbon nanoparticles prepared by mechanical mixing

Energy Technology Data Exchange (ETDEWEB)

Saatchi, M.M. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, P.O. Box 11155-9465, Tehran (Iran, Islamic Republic of); Shojaei, A., E-mail: akbar.shojaei@sharif.edu [Department of Chemical and Petroleum Engineering, Sharif University of Technology, P.O. Box 11155-9465, Tehran (Iran, Islamic Republic of)

2011-09-15

Highlights: {yields} We compare influence of carbon blacks and carbon nanotube on properties of SBR. {yields} We model mechanical behavior of SBR nanocomposites by the micromechanical model. {yields} Mechanical properties of carbon black/SBR is greatly dominated by bound rubber. {yields} Mechanical properties of SBR/nanotube is governed by big aspect ratio of nanotube. - Abstract: Reinforcement of styrene-butadiene-rubber (SBR) was investigated using two different carbon blacks (CBs) with similar particle sizes, including highly structured CB and conventional CB, as well as multi-walled carbon nanotube (MWCNT) prepared by mechanical mixing. The attempts were made to examine reinforcing mechanism of these two different classes of carbon nanoparticles. Scanning electron microscopy and electrical conductivity measurement were used to investigate morphology. Tensile, cyclic tensile and stress relaxation analyses were performed. A modified Halpin-Tsai model based on the concept of an equivalent composite particle, consisting of rubber bound, occluded rubber and nanoparticle, was proposed. It was found that properties of CB filled SBR are significantly dominated by rubber shell and occluded rubber in which molecular mobility is strictly restricted. At low strains, these rubber constituents can contribute in hydrodynamic effects, leading to higher elastic modulus. However, at higher strains, they contribute in stress hardening resulting in higher elongation at break and higher tensile strength. These elastomeric regions can also influence stress relaxation behaviors of CB filled rubber. For SBR/MWCNT, the extremely great inherent mechanical properties of nanotube along with its big aspect ratio were postulated to be responsible for the reinforcement while their interfacial interaction was not so efficient.

Mechanical characterisation of agarose-based chromatography resins for biopharmaceutical manufacture.

Science.gov (United States)

Nweke, Mauryn C; McCartney, R Graham; Bracewell, Daniel G

2017-12-29

Mechanical characterisation of agarose-based resins is an important factor in ensuring robust chromatographic performance in the manufacture of biopharmaceuticals. Pressure-flow profiles are most commonly used to characterise these properties. There are a number of drawbacks with this method, including the potential need for several re-packs to achieve the desired packing quality, the impact of wall effects on experimental set up and the quantities of chromatography media and buffers required. To address these issues, we have developed a dynamic mechanical analysis (DMA) technique that characterises the mechanical properties of resins based on the viscoelasticity of a 1ml sample of slurry. This technique was conducted on seven resins with varying degrees of mechanical robustness and the results were compared to pressure-flow test results on the same resins. Results show a strong correlation between the two techniques. The most mechanically robust resin (Capto Q) had a critical velocity 3.3 times higher than the weakest (Sepharose CL-4B), whilst the DMA technique showed Capto Q to have a slurry deformation rate 8.3 times lower than Sepharose CL-4B. To ascertain whether polymer structure is indicative of mechanical strength, scanning electron microscopy images were also used to study the structural properties of each resin. Results indicate that DMA can be used as a small volume, complementary technique for the mechanical characterisation of chromatography media. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Optimization evaluation of cutting technology based on mechanical parts

Science.gov (United States)

Wang, Yu

2018-04-01

The relationship between the mechanical manufacturing process and the carbon emission is studied on the basis of the process of the mechanical manufacturing process. The formula of carbon emission calculation suitable for mechanical manufacturing process is derived. Based on this, a green evaluation method for cold machining process of mechanical parts is proposed. The application verification and data analysis of the proposed evaluation method are carried out by an example. The results show that there is a great relationship between the mechanical manufacturing process data and carbon emissions.

NLC Mechanical

Science.gov (United States)

text only Mechanical Systems.gif (14697 bytes) NLC Home Page NLC Technical SLAC Permanent Magnets Organization Overview The Mechanical Systems Group Organization is shown on the NLC Project Group Organization Chart (Next Linear Collider Technical Web Page). The Mechanical Systems Group operates on a matrixed

Microfluidics as a functional tool for cell mechanics.

Science.gov (United States)

Vanapalli, Siva A; Duits, Michel H G; Mugele, Frieder

2009-01-05

Living cells are a fascinating demonstration of nature's most intricate and well-coordinated micromechanical objects. They crawl, spread, contract, and relax-thus performing a multitude of complex mechanical functions. Alternatively, they also respond to physical and chemical cues that lead to remodeling of the cytoskeleton. To understand this intricate coupling between mechanical properties, mechanical function and force-induced biochemical signaling requires tools that are capable of both controlling and manipulating the cell microenvironment and measuring the resulting mechanical response. In this review, the power of microfluidics as a functional tool for research in cell mechanics is highlighted. In particular, current literature is discussed to show that microfluidics powered by soft lithographic techniques offers the following capabilities that are of significance for understanding the mechanical behavior of cells: (i) Microfluidics enables the creation of in vitro models of physiological environments in which cell mechanics can be probed. (ii) Microfluidics is an excellent means to deliver physical cues that affect cell mechanics, such as cell shape, fluid flow, substrate topography, and stiffness. (iii) Microfluidics can also expose cells to chemical cues, such as growth factors and drugs, which alter their mechanical behavior. Moreover, these chemical cues can be delivered either at the whole cell or subcellular level. (iv) Microfluidic devices offer the possibility of measuring the intrinsic mechanical properties of cells in a high throughput fashion. (v) Finally, microfluidic methods provide exquisite control over drop size, generation, and manipulation. As a result, droplets are being increasingly used to control the physicochemical environment of cells and as biomimetic analogs of living cells. These powerful attributes of microfluidics should further stimulate novel means of investigating the link between physicochemical cues and the biomechanical

Mechanical properties of additively manufactured octagonal honeycombs

Energy Technology Data Exchange (ETDEWEB)

Hedayati, R., E-mail: rezahedayati@gmail.com [Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran (Iran, Islamic Republic of); Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Sadighi, M.; Mohammadi-Aghdam, M. [Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran (Iran, Islamic Republic of); Zadpoor, A.A. [Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands)

2016-12-01

Honeycomb structures have found numerous applications as structural and biomedical materials due to their favourable properties such as low weight, high stiffness, and porosity. Application of additive manufacturing and 3D printing techniques allows for manufacturing of honeycombs with arbitrary shape and wall thickness, opening the way for optimizing the mechanical and physical properties for specific applications. In this study, the mechanical properties of honeycomb structures with a new geometry, called octagonal honeycomb, were investigated using analytical, numerical, and experimental approaches. An additive manufacturing technique, namely fused deposition modelling, was used to fabricate the honeycomb from polylactic acid (PLA). The honeycombs structures were then mechanically tested under compression and the mechanical properties of the structures were determined. In addition, the Euler-Bernoulli and Timoshenko beam theories were used for deriving analytical relationships for elastic modulus, yield stress, Poisson's ratio, and buckling stress of this new design of honeycomb structures. Finite element models were also created to analyse the mechanical behaviour of the honeycombs computationally. The analytical solutions obtained using Timoshenko beam theory were close to computational results in terms of elastic modulus, Poisson's ratio and yield stress, especially for relative densities smaller than 25%. The analytical solutions based on the Timoshenko analytical solution and the computational results were in good agreement with experimental observations. Finally, the elastic properties of the proposed honeycomb structure were compared to those of other honeycomb structures such as square, triangular, hexagonal, mixed, diamond, and Kagome. The octagonal honeycomb showed yield stress and elastic modulus values very close to those of regular hexagonal honeycombs and lower than the other considered honeycombs. - Highlights: • The octagonal

Tokamak engineering mechanics

International Nuclear Information System (INIS)

Song, Yuntao; Wu, Weiyue; Du, Shijun

2014-01-01

Provides a systematic introduction to tokamaks in engineering mechanics. Includes design guides based on full mechanical analysis, which makes it possible to accurately predict load capacity and temperature increases. Presents comprehensive information on important design factors involving materials. Covers the latest advances in and up-to-date references on tokamak devices. Numerous examples reinforce the understanding of concepts and provide procedures for design. Tokamak Engineering Mechanics offers concise and thorough coverage of engineering mechanics theory and application for tokamaks, and the material is reinforced by numerous examples. Chapter topics include general principles, static mechanics, dynamic mechanics, thermal fluid mechanics and multiphysics structural mechanics of tokamak structure analysis. The theoretical principle of the design and the methods of the analysis for various components and load conditions are presented, while the latest engineering technologies are also introduced. The book will provide readers involved in the study of mechanical/fusion engineering with a general understanding of tokamak engineering mechanics.

Atomistic modeling of mechanical properties of polycrystalline graphene

International Nuclear Information System (INIS)

Mortazavi, Bohayra; Cuniberti, Gianaurelio

2014-01-01

We performed molecular dynamics (MD) simulations to investigate the mechanical properties of polycrystalline graphene. By constructing molecular models of ultra-fine-grained graphene structures, we studied the effect of different grain sizes of 1–10 nm on the mechanical response of graphene. We found that the elastic modulus and tensile strength of polycrystalline graphene decrease with decreasing grain size. The calculated mechanical proprieties for pristine and polycrystalline graphene sheets are found to be in agreement with experimental results in the literature. Our MD results suggest that the ultra-fine-grained graphene structures can show ultrahigh tensile strength and elastic modulus values that are very close to those of pristine graphene sheets. (papers)

Mechanisms of traumatic shoulder injury in elite rugby players

Science.gov (United States)

Crichton, James; Jones, Doug R; Funk, Lennard

2012-01-01

Background Shoulder injuries in rugby players are common, but the mechanisms of injury are less well understood. This study aims to elucidate common mechanisms of injury and identify the patterns of injury they produce. Materials and methods Twenty-four elite rugby players, referred to the senior author for diagnosis and management of shoulder injuries, were selected. Videos of the injuries were independently reviewed by rugby-medical experts to describe the mechanisms of injury. The mechanisms reported were collated and analysed to determine the level of agreement between reviewers and conclude an overall description of injury mechanisms. Results The authors identified three mechanisms of shoulder injury from the video analysis. These are the ‘Try-Scorer’, characterised by hyperflexion of the outstretched arm such as when scoring a try; the ‘Tackler’, extension of the abducted arm behind the player while tackling; and the ‘Direct Impact’, a direct blow to the arm or shoulder when held by the side in neutral or slight adduction. The Try Scorer and Tackler mechanisms both involve a levering force on the glenohumeral joint (GHJ). These mechanisms predominantly cause GHJ dislocation, with Bankart, reverse Bankart and superior labrum anterior–posterior tears. The Try-Scorer Mechanism also caused the majority (83%) of rotator cuff tears. The Direct Hit mechanism resulted in GHJ dislocation and labral injury in 37.5% of players and was most likely to cause acromioclavicular joint dislocation and scapula fractures, injuries that were not seen with the other mechanisms. Conclusion Greater understanding of the mechanisms involved in rugby shoulder injury is useful in understanding the pathological injuries, guiding treatment and rehabilitation and aiding the development of injury-prevention methods. PMID:22510645

Mechanical failure and glass transition in metallic glasses

International Nuclear Information System (INIS)

Egami, T.

2011-01-01

Research highlights: → We review the recent results of molecular dynamics simulations on metallic glasses. → They show the equivalence of mechanical failure and glass transition. → We discuss the microscopic mechanism behind this equivalence. → We show that the density of defects in metallic glasses is as high as a quarter. → Our concepts about the defect state in glasses need to be changed. - Abstract: The current majority view on the phenomenon of mechanical failure in metallic glasses appears to be that it is caused by the activity of some structural defects, such as free-volumes or shear transformation zones, and the concentration of such defects is small, only of the order of 1%. However, the recent results compel us to revise this view. Through molecular dynamics simulation it has been shown that mechanical failure is the stress-induced glass transition. According to our theory the concentration of the liquid-like sites (defects) is well over 20% at the glass transition. We suggest that the defect concentration in metallic glasses is actually very high, and percolation of such defects causes atomic avalanche and mechanical failure. In this article we discuss the glass transition, mechanical failure and viscosity from such a point of view.

The scalar spectrum of the triple seesaw mechanism

International Nuclear Information System (INIS)

Caetano, Wellington; Pires, Carlos

2011-01-01

Full text: The Triple seesaw mechanism provides an expression to the neutrino masses which get suppressed by high-scale M 3 in its denominator. Thus, we have a seesaw mechanism which works naturally at TeV scale, presenting, in this way, a great potential of being probed at LHC. In order to generate the small left-handed neutrino masses, the triple seesaw mechanism also requires only heavy right-handed neutrinos as extra fermionic content as the type I seesaw. The minimum Higgs sector required by the mechanism is composed by the standard Higgs doublet plus another Higgs doublet and a Higgs singlet. In this work we obtain the mass spectrum and the eigenvectors of the scalar sector that realizes the Triple seesaw mechanism. As our results, we recover the standard Higgs boson with mass in a region at 116 H < 151 GeV. We analyzed the expression given in the Triple seesaw mechanism for the neutrino mass in a scenario that is consistent with the small mass from the neutrino oscillation data and compatible with the requirements for a WIMP (weakly interacting massive particles) candidate. Finally, we obtain, as our main result, a neutral pseudoscalar with mass around 8-10 GeV which is stable and can be a possible WIMP dark matter candidate. (author)

Diffusion mechanisms in intermetallic compounds

Energy Technology Data Exchange (ETDEWEB)

Larikov, L N [ANU, Inst. Metallofiziki, Kiev (Ukraine)

1992-08-01

Recent research aimed at the identification of the principal mechanisms of diffusion in intermetallics is reviewed. In particular, attention is given to the effect of the type of interatomic bond on the contribution of different mechanisms to diffusion in ordered metallic compounds. Results of an analysis of experimental determinations of diffusion coefficients D(A) and D(B) in binary intermetallics (CuZn, Cu3Sn, AuCd, AgZn, AgMg, InSb, GaSb, AlSb, Fe3Al, FeAl, FeAl3, Ni3Al, Ni3Nb, FeSn, FeSn2, Ni3Sn2, Ni3Sn4, Co3Sn2, CoSn, CoSn2, and CoGa) are presented, and it is shown that the D(A)/D(B) ratio differs substantially for different diffusion mechanisms. 60 refs.

Pairing mechanism in oxide superconductors

International Nuclear Information System (INIS)

Hirsch, J.E.

1988-01-01

A useful way to learn about the pairing mechanism that is responsible for high T c superconductivity is to study properties of model Hamiltonians on small systems. The goal is to find the simplest model that can describe the essential physics of high T c superconductivity. The authors have used Monte Carlo simulation and exact diagonalization techniques to study properties of systems of up to 64 sites. Their results show that spin fluctuations and other spin related mechanisms induced by a Hubbard on-site repulsion U are not likely to give rise to pairing, neither in one nor in multiple band models. In contrast, charge fluctuations in a model with both strong U and V (repulsion between Cu and O) are shown to give rise to pairing and it is suggested that this model provides a plausible mechanism for high T c superconductivity

MECHANISMS OF NITROUS OXIDE FORMATION IN COAL FLAMES

Science.gov (United States)

The paper gives results of a study, using both detailed kinetic modeling and plug-flow simulator experiments, to investigate an unknown mechanism by which N2O is formed in coal flames. This mechanism has considerable importance in determining the influence of common and advanced ...

A Review of the Mechanism of Injury and Treatment Approaches for Illness Resulting from Exposure to Water-Damaged Buildings, Mold, and Mycotoxins

Directory of Open Access Journals (Sweden)

Janette Hope

2013-01-01

Full Text Available Physicians are increasingly being asked to diagnose and treat people made ill by exposure to water-damaged environments, mold, and mycotoxins. In addition to avoidance of further exposure to these environments and to items contaminated by these environments, a number of approaches have been used to help persons affected by exposure to restore their health. Illness results from a combination of factors present in water-damaged indoor environments including, mold spores and hyphal fragments, mycotoxins, bacteria, bacterial endotoxins, and cell wall components as well as other factors. Mechanisms of illness include inflammation, oxidative stress, toxicity, infection, allergy, and irritant effects of exposure. This paper reviews the scientific literature as it relates to commonly used treatments such as glutathione, antioxidants, antifungals, and sequestering agents such as Cholestyramine, charcoal, clay and chlorella, antioxidants, probiotics, and induced sweating.

Mechanical engineering education

CERN Document Server

Davim, J Paulo

2012-01-01

Mechanical Engineering is defined nowadays as a discipline "which involves the application of principles of physics, design, manufacturing and maintenance of mechanical systems". Recently, mechanical engineering has also focused on some cutting-edge subjects such as nanomechanics and nanotechnology, mechatronics and robotics, computational mechanics, biomechanics, alternative energies, as well as aspects related to sustainable mechanical engineering.This book covers mechanical engineering higher education with a particular emphasis on quality assurance and the improvement of academic

Antiviral Defense Mechanisms in Honey Bees

Science.gov (United States)

Brutscher, Laura M.; Daughenbaugh, Katie F.; Flenniken, Michelle L.

2015-01-01

Honey bees are significant pollinators of agricultural crops and other important plant species. High annual losses of honey bee colonies in North America and in some parts of Europe have profound ecological and economic implications. Colony losses have been attributed to multiple factors including RNA viruses, thus understanding bee antiviral defense mechanisms may result in the development of strategies that mitigate colony losses. Honey bee antiviral defense mechanisms include RNA-interference, pathogen-associated molecular pattern (PAMP) triggered signal transduction cascades, and reactive oxygen species generation. However, the relative importance of these and other pathways is largely uncharacterized. Herein we review the current understanding of honey bee antiviral defense mechanisms and suggest important avenues for future investigation. PMID:26273564

ANALYSIS AND MODELING OF GENEVA MECHANISM

Directory of Open Access Journals (Sweden)

HARAGA Georgeta

2015-06-01

Full Text Available The paper presents some aspects theoretical and practical based on the finite element analysis and modelling of Geneva mechanism with four slots, using the CATIA graphic program. This type of mechanism is an example of intermittent gearing that translates a continuous rotation into an intermittent rotary motion. It consists of alternate periods of motion and rest without reversing direction. In this paper, some design parameters with specify a Geneva mechanism will be defined precisely such as number of driving cranks, number of slots, wheel diameter, pin diameter, etc. Finite element analysis (FEA can be used for creating a finite element model (preprocessing and visualizing the analysis results (postprocessing, and use other solvers for processing.

Serotonergic mechanisms in the migraine brain

DEFF Research Database (Denmark)

Christensen, Marie Deen; Christensen, Casper Emil; Hougaard, Anders

2017-01-01

role of brain serotonergic mechanisms remains a matter of controversy. Methods We systematically searched PubMed for studies investigating the serotonergic system in the migraine brain by either molecular neuroimaging or electrophysiological methods. Results The literature search resulted in 59 papers......, of which 13 were eligible for review. The reviewed papers collectively support the notion that migraine patients have alterations in serotonergic neurotransmission. Most likely, migraine patients have a low cerebral serotonin level between attacks, which elevates during a migraine attack. Conclusion...... This review suggests that novel methods of investigating the serotonergic system in the migraine brain are warranted. Uncovering the serotonergic mechanisms in migraine pathophysiology could prove useful for the development of future migraine drugs....

Modelling Cochlear Mechanics

Directory of Open Access Journals (Sweden)

Guangjian Ni

2014-01-01

Full Text Available The cochlea plays a crucial role in mammal hearing. The basic function of the cochlea is to map sounds of different frequencies onto corresponding characteristic positions on the basilar membrane (BM. Sounds enter the fluid-filled cochlea and cause deflection of the BM due to pressure differences between the cochlear fluid chambers. These deflections travel along the cochlea, increasing in amplitude, until a frequency-dependent characteristic position and then decay away rapidly. The hair cells can detect these deflections and encode them as neural signals. Modelling the mechanics of the cochlea is of help in interpreting experimental observations and also can provide predictions of the results of experiments that cannot currently be performed due to technical limitations. This paper focuses on reviewing the numerical modelling of the mechanical and electrical processes in the cochlea, which include fluid coupling, micromechanics, the cochlear amplifier, nonlinearity, and electrical coupling.

The strength study of the rotating device driver indexing spatial mechanism

Science.gov (United States)

Zakharenkov, N. V.; Kvasov, I. N.

2018-04-01

The indexing spatial mechanisms are widely used in automatic machines. The mechanisms maximum load-bearing capacity measurement is possible based on both the physical and numerical models tests results. The paper deals with the driven disk indexing spatial cam mechanism numerical model at the constant angular cam velocity. The presented mechanism kinematics and geometry parameters and finite element model are analyzed in the SolidWorks design environment. The calculation initial data and missing parameters having been found from the structure analysis were identified. The structure and kinematics analysis revealed the mechanism failures possible reasons. The numerical calculations results showing the structure performance at the contact and bending stresses are represented.

Synthesis of radiolabelled aryl azides from diazonium salts: experimental and computational results permit the identification of the preferred mechanism.

Science.gov (United States)

Joshi, Sameer M; de Cózar, Abel; Gómez-Vallejo, Vanessa; Koziorowski, Jacek; Llop, Jordi; Cossío, Fernando P

2015-05-28

Experimental and computational studies on the formation of aryl azides from the corresponding diazonium salts support a stepwise mechanism via acyclic zwitterionic intermediates. The low energy barriers associated with both transition structures are compatible with very fast and efficient processes, thus making this method suitable for the chemical synthesis of radiolabelled aryl azides.

Analogies between classical statistical mechanics and quantum mechanics

International Nuclear Information System (INIS)

Uehara, M.

1986-01-01

Some analogies between nonequilibrium classical statistical mechanics and quantum mechanics, at the level of the Liouville equation and at the kinetic level, are commented on. A theorem, related to the Vlasov equation applied to a plasma, is proved. The theorem presents an analogy with Ehrenfest's theorem of quantum mechanics. An analogy between the plasma kinetic theory and Bohm's quantum theory with 'hidden variables' is also shown. (Author) [pt

Cross-border effects of capacity mechanisms in electricity markets

International Nuclear Information System (INIS)

Elberg, Christina

2014-01-01

To ensure security of supply in liberalized electricity markets, different types of capacity mechanisms are currently being debated or have recently been implemented in many European countries. The purpose of this study is to analyze the cross-border effects resulting from different choices on capacity mechanisms in neighboring countries. We consider a model with two connected countries that differ in the regulator's choice on capacity mechanism, namely strategic reserves or capacity payments. In both countries, competitive fi rms invest in generation capacity before selling electricity on the spot market. We characterize market equilibria and find the following main result: While consumers' costs may be the same under both capacity mechanisms in non-connected countries, we show that the different capacity mechanisms in interconnected countries induce redistribution effects. More precisely, we nd that consumers' costs are higher in countries in which reserve capacities are procured than in countries in which capacity payments are used to ensure the targeted reliable level of electricity.

Cross-border effects of capacity mechanisms in electricity markets

Energy Technology Data Exchange (ETDEWEB)

Elberg, Christina

2014-07-15

To ensure security of supply in liberalized electricity markets, different types of capacity mechanisms are currently being debated or have recently been implemented in many European countries. The purpose of this study is to analyze the cross-border effects resulting from different choices on capacity mechanisms in neighboring countries. We consider a model with two connected countries that differ in the regulator's choice on capacity mechanism, namely strategic reserves or capacity payments. In both countries, competitive fi rms invest in generation capacity before selling electricity on the spot market. We characterize market equilibria and find the following main result: While consumers' costs may be the same under both capacity mechanisms in non-connected countries, we show that the different capacity mechanisms in interconnected countries induce redistribution effects. More precisely, we nd that consumers' costs are higher in countries in which reserve capacities are procured than in countries in which capacity payments are used to ensure the targeted reliable level of electricity.

Excitation mechanisms in 1 mJ picosecond laser induced low pressure He plasma and the resulting spectral quality enhancement

Energy Technology Data Exchange (ETDEWEB)

Idris, Nasrullah; Lahna, Kurnia; Abdulmadjid, Syahrun Nur [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Ramli, Muliadi [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Suyanto, Hery [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Marpaung, Alion Mangasi [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, 10 Rawamangun, Jakarta (Indonesia); Pardede, Marincan [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Jobiliong, Eric [Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Hedwig, Rinda; Lie, Zener Sukra [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Suliyanti, Maria Margaretha [Research Center for Physics, Indonesia Institute of Sciences, Kawasan PUSPIPTEK, Serpong, Tangerang Selatan 15314, Banten (Indonesia); Lie, Tjung Jie; Kurniawan, Koo Hendrik, E-mail: kurnia18@cbn.net.id [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Kagawa, Kiichiro [Fukui Science Education Academy, Takagi Chuou 2 choume, Fukui 910-0804 (Japan); Tjia, May On [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia)

2015-06-14

We report in this paper the results of an experimental study on the spectral and dynamical characteristics of plasma emission induced by 1 mJ picoseconds (ps) Nd-YAG laser using spatially resolved imaging and time resolved measurement of the emission intensities of copper sample. This study has provided the experimental evidence concerning the dynamical characteristics of the excitation mechanisms in various stages of the plasma formation, which largely consolidate the basic scenarios of excitation processes commonly accepted so far. However, it is also clearly shown that the duration of the shock wave excitation process induced by ps laser pulses is much shorter than those observed in laser induced breakdown spectroscopy employing nanosecond laser at higher output energy. This allows the detection of atomic emission due exclusively to He assisted excitation in low pressure He plasma by proper gating of the detection time. Furthermore, the triplet excited state associated with He I 587.6 nm is shown to be the one most likely involved in the process responsible for the excellent spectral quality as evidenced by its application to spectrochemical analysis of a number of samples. The use of very low energy laser pulses also leads to minimal destructive effect marked by the resulted craters of merely about 10 μm diameter and only 10 nm deep. It is especially noteworthy that the excellent emission spectrum of deuterium detected from D-doped titanium sample is free of spectral interference from the undesirable ubiquitous water molecules without a precleaning procedure as applied previously and yielding an impressive detection limit of less than 10 μg/g. Finally, the result of this study also shows a promising application to depth profiling of impurity distribution in the sample investigated.

Continuum Mechanics

CERN Document Server

Romano, Antonio

2010-01-01

This book offers a broad overview of the potential of continuum mechanics to describe a wide range of macroscopic phenomena in real-world problems. Building on the fundamentals presented in the authors' previous book, Continuum Mechanics using Mathematica(R), this new work explores interesting models of continuum mechanics, with an emphasis on exploring the flexibility of their applications in a wide variety of fields.Specific topics, which have been chosen to show the power of continuum mechanics to characterize the experimental behavior of real phenomena, include: * various aspects of nonlin

Mechanical engineer's handbook

CERN Document Server

Marghitu, Dan B

2001-01-01

The Mechanical Engineer's Handbook was developed and written specifically to fill a need for mechanical engineers and mechanical engineering students throughout the world. With over 1000 pages, 550 illustrations, and 26 tables the Mechanical Engineer's Handbook is very comprehensive, yet affordable, compact, and durable. The Handbook covers all major areas of mechanical engineering with succinct coverage of the definitions, formulas, examples, theory, proofs, and explanations of all principle subject areas. The Handbook is an essential, practical companion for all mechanic

Tokamak engineering mechanics

CERN Document Server

Song, Yuntao; Du, Shijun

2013-01-01

Tokamak Engineering Mechanics offers concise and thorough coverage of engineering mechanics theory and application for tokamaks, and the material is reinforced by numerous examples. Chapter topics include general principles, static mechanics, dynamic mechanics, thermal fluid mechanics and multiphysics structural mechanics of tokamak structure analysis. The theoretical principle of the design and the methods of the analysis for various components and load conditions are presented, while the latest engineering technologies are also introduced. The book will provide readers involved in the study

Alloy design through mechanical equation of state

International Nuclear Information System (INIS)

Li, C.Yu.; Ellis, F.V.; Huang, F.H.

1975-01-01

The concept of plastic equation of state and the experimental results which are used to support this approach are introduced. It is shown that considerable savings in mechanical testing are possible in using this approach to establish the constitutive relationships for plastic deformation for a material. Advantages in data correlation and data extrapolation are also described. Examples are given to suggest that the constitutive relationships for plastic deformation obtained may be used as a useful basis for correlating the effects of composition and microstructure changes on mechanical properties and therefore serve as a guide for alloy selection. The savings in mechanical testing suggest also that the approach of plastic equation of state may be adopted for evaluating and assessing the mechanical properties of candidate alloys

Characterization and modelling of the mechanical properties of mineral wool

DEFF Research Database (Denmark)

Chapelle, Lucie

2016-01-01

and as a consequence focus on the mechanical properties of mineral wool has intensified. Also understanding the deformation mechanisms during compression of low density mineral wool is crucial since better thickness recovery after compression will result in significant savings on transport costs. The mechanical...... properties of mineral wool relate closely to the arrangement and characteristics of the fibres inside the material. Because of the complex architecture of mineral wool, the characterization and the understanding of the mechanism of deformations require a new methodology. In this PhD thesis, a methodology...... of the structure on mechanical properties can be explored. The size of the representative volume elements for the prediction of the elastic properties is determined for two types of applied boundary conditions. For sufficiently large volumes, the predicted elastic properties are consistent with results from...

Fluids and the evolution of rock mechanical properties

International Nuclear Information System (INIS)

Reuschle, Thierry

1989-01-01

This research thesis reports the study of the various phenomena of fluid-solid interaction (mechanical or chemical interaction with fracturing by fluid overpressure, slow crack propagation, and pore deformation by transfer in solution) which may occur in the interaction of fluids with rocks. The author first presents the formalism of slow crack propagation based on the generalisation of the Griffith criterion. The model results are compared with experimental results obtained on four materials (glass, quartz, sandstone, and micrite) by using the double-torsion test. In the second part, the author addresses the issue of pore deformation by transfer in solution: dissolution and crystallisation under stress. The Gibbs chemical potential equation is firstly generalised to the case of a circular pore, and a formalism combining mechanics and thermodynamics is then proposed. A set of simulations highlights important parameters. In the third part, the author addresses the problem of fluid-rock mechanical interaction by studying the mechanical role of fluid pressure in crack initiation and propagation [fr

Illustrating how mechanical assemblies work

KAUST Repository

Mitra, Niloy J.; Yang, Yongliang; Yan, Dongming; Li, Wilmot; Agrawala, Maneesh

2010-01-01

How things work visualizations use a variety of visual techniques to depict the operation of complex mechanical assemblies. We present an automated approach for generating such visualizations. Starting with a 3D CAD model of an assembly, we first infer the motions of individual parts and the interactions between parts based on their geometry and a few user specified constraints. We then use this information to generate visualizations that incorporate motion arrows, frame sequences and animation to convey the causal chain of motions and mechanical interactions between parts. We present results for a wide variety of assemblies. © 2010 ACM.

Illustrating how mechanical assemblies work

KAUST Repository

Mitra, Niloy J.

2010-07-26

How things work visualizations use a variety of visual techniques to depict the operation of complex mechanical assemblies. We present an automated approach for generating such visualizations. Starting with a 3D CAD model of an assembly, we first infer the motions of individual parts and the interactions between parts based on their geometry and a few user specified constraints. We then use this information to generate visualizations that incorporate motion arrows, frame sequences and animation to convey the causal chain of motions and mechanical interactions between parts. We present results for a wide variety of assemblies. © 2010 ACM.

Probabilistic application of fracture mechanics

International Nuclear Information System (INIS)

Dufresne, J.

1981-04-01

The different methods used to evaluate the rupture probability of a pressure vessel are reviewed. Data collection and processing of all parameters necessary for fracture mechanics evaluation are presented with particular attention to the size distribution of defects in actual vessels. Physical process is followed during crack growth and unstable propagation, using LEFM (Linear Elastic Fracture Mechanism) and plastic instability. Results show that the final failure probability for a PWR pressure vessel is 3.5 10 -8 , and is due essentially to LOCAs for any break size. The weakest point is the internal side of the belt line

Principles of Mechanical Excavation

International Nuclear Information System (INIS)

Lislerud, A.

1997-12-01

Mechanical excavation of rock today includes several methods such as tunnel boring, raiseboring, roadheading and various continuous mining systems. Of these raiseboring is one potential technique for excavating shafts in the repository for spent nuclear fuel and dry blind boring is promising technique for excavation of deposition holes, as demonstrated in the Research Tunnel at Olkiluoto. In addition, there is potential for use of other mechanical excavation techniques in different parts of the repository. One of the main objectives of this study was to analyze the factors which affect the feasibility of mechanical rock excavation in hard rock conditions and to enhance the understanding of factors which affect rock cutting so as to provide an improved basis for excavator performance prediction modeling. The study included the following four main topics: (a) phenomenological model based on similarity analysis for roller disk cutting, (b) rock mass properties which affect rock cuttability and tool life, (c) principles for linear and field cutting tests and performance prediction modeling and (d) cutter head lacing design procedures and principles. As a conclusion of this study, a test rig was constructed, field tests were planned and started up. The results of the study can be used to improve the performance prediction models used to assess the feasibility of different mechanical excavation techniques at various repository investigation sites. (orig.)

Principles of Mechanical Excavation

Energy Technology Data Exchange (ETDEWEB)

Lislerud, A. [Tamrock Corp., Tampere (Finland)

1997-12-01

Mechanical excavation of rock today includes several methods such as tunnel boring, raiseboring, roadheading and various continuous mining systems. Of these raiseboring is one potential technique for excavating shafts in the repository for spent nuclear fuel and dry blind boring is promising technique for excavation of deposition holes, as demonstrated in the Research Tunnel at Olkiluoto. In addition, there is potential for use of other mechanical excavation techniques in different parts of the repository. One of the main objectives of this study was to analyze the factors which affect the feasibility of mechanical rock excavation in hard rock conditions and to enhance the understanding of factors which affect rock cutting so as to provide an improved basis for excavator performance prediction modeling. The study included the following four main topics: (a) phenomenological model based on similarity analysis for roller disk cutting, (b) rock mass properties which affect rock cuttability and tool life, (c) principles for linear and field cutting tests and performance prediction modeling and (d) cutter head lacing design procedures and principles. As a conclusion of this study, a test rig was constructed, field tests were planned and started up. The results of the study can be used to improve the performance prediction models used to assess the feasibility of different mechanical excavation techniques at various repository investigation sites. (orig.). 21 refs.

Significance of mineralogy in soil mechanics

Directory of Open Access Journals (Sweden)

Bojana Dolinar

2002-12-01

Full Text Available The research of consistency limits according to Atterberg is of key importance in soil mechanics because it determines, in a simple way, results of interactions between solid and liquid phases in soils, and thus provides possibility to classify them in groups withsimilar mechanic properties. In most cases, the results of these investigations provide a good basis for predicting other properties such as deformability, expansion, hydraulic conductivity and strength of soils. This proves that basis factors influencing the valuesof consistency limits and other mechanic properties are the same. It is known that the values of consistency limits primarily depend on the type and quantity of clay minerals in soils. The article focuses on experimental evidence of dependence between the quantityof water at the liquid limit for soils and type, portion and specific surface of clay grains.Experiments were performed with monomineral soils, their mixtures and composed samples of clay- and non-clay components. It was established that in parallel orientation of clay particles the quantity of water between grains at liquid limit is dependent on their external specific surface.

Gas Bubble Dynamics under Mechanical Vibrations

Science.gov (United States)

Mohagheghian, Shahrouz; Elbing, Brian

2017-11-01

The scientific community has a limited understanding of the bubble dynamics under mechanical oscillations due to over simplification of Navier-Stockes equation by neglecting the shear stress tensor and not accounting for body forces when calculating the acoustic radiation force. The current work experimental investigates bubble dynamics under mechanical vibration and resulting acoustic field by measuring the bubble size and velocity using high-speed imaging. The experimental setup consists of a custom-designed shaker table, cast acrylic bubble column, compressed air injection manifold and an optical imaging system. The mechanical vibrations resulted in accelerations between 0.25 to 10 times gravitational acceleration corresponding to frequency and amplitude range of 8 - 22Hz and 1 - 10mm respectively. Throughout testing the void fraction was limited to <5%. The bubble size is larger than resonance size and smaller than acoustic wavelength. The amplitude of acoustic pressure wave was estimated using the definition of Bjerknes force in combination with Rayleigh-Plesset equation. Physical behavior of the system was capture and classified. Bubble size, velocity as well as size and spatial distribution will be presented.

Mechanical Stress Promotes Cisplatin-Induced Hepatocellular Carcinoma Cell Death

Science.gov (United States)

Riad, Sandra; Bougherara, Habiba

2015-01-01

Cisplatin (CisPt) is a commonly used platinum-based chemotherapeutic agent. Its efficacy is limited due to drug resistance and multiple side effects, thereby warranting a new approach to improving the pharmacological effect of CisPt. A newly developed mathematical hypothesis suggested that mechanical loading, when coupled with a chemotherapeutic drug such as CisPt and immune cells, would boost tumor cell death. The current study investigated the aforementioned mathematical hypothesis by exposing human hepatocellular liver carcinoma (HepG2) cells to CisPt, peripheral blood mononuclear cells, and mechanical stress individually and in combination. HepG2 cells were also treated with a mixture of CisPt and carnosine with and without mechanical stress to examine one possible mechanism employed by mechanical stress to enhance CisPt effects. Carnosine is a dipeptide that reportedly sequesters platinum-based drugs away from their pharmacological target-site. Mechanical stress was achieved using an orbital shaker that produced 300 rpm with a horizontal circular motion. Our results demonstrated that mechanical stress promoted CisPt-induced death of HepG2 cells (~35% more cell death). Moreover, results showed that CisPt-induced death was compromised when CisPt was left to mix with carnosine 24 hours preceding treatment. Mechanical stress, however, ameliorated cell death (20% more cell death). PMID:25685789

Mechanical Stress Promotes Cisplatin-Induced Hepatocellular Carcinoma Cell Death

Directory of Open Access Journals (Sweden)

Laila Ziko

2015-01-01

Full Text Available Cisplatin (CisPt is a commonly used platinum-based chemotherapeutic agent. Its efficacy is limited due to drug resistance and multiple side effects, thereby warranting a new approach to improving the pharmacological effect of CisPt. A newly developed mathematical hypothesis suggested that mechanical loading, when coupled with a chemotherapeutic drug such as CisPt and immune cells, would boost tumor cell death. The current study investigated the aforementioned mathematical hypothesis by exposing human hepatocellular liver carcinoma (HepG2 cells to CisPt, peripheral blood mononuclear cells, and mechanical stress individually and in combination. HepG2 cells were also treated with a mixture of CisPt and carnosine with and without mechanical stress to examine one possible mechanism employed by mechanical stress to enhance CisPt effects. Carnosine is a dipeptide that reportedly sequesters platinum-based drugs away from their pharmacological target-site. Mechanical stress was achieved using an orbital shaker that produced 300 rpm with a horizontal circular motion. Our results demonstrated that mechanical stress promoted CisPt-induced death of HepG2 cells (~35% more cell death. Moreover, results showed that CisPt-induced death was compromised when CisPt was left to mix with carnosine 24 hours preceding treatment. Mechanical stress, however, ameliorated cell death (20% more cell death.

Foundations of mechanics

International Nuclear Information System (INIS)

Zorski, Henryk; Bazanski, Stanislaw; Gutowski, Roman; Slawianowski, Jan; Wilmanski, Krysztof; Wozniak, Czeslaw

1992-01-01

In the last 3 decades the field of mechanics has seen spectacular progress due to the demand for applications in problems of cosmology, thermonuclear fusion, metallurgy, etc. This book provides a broad and thorough overview on the foundations of mechanics. It discusses theoretical mechanics and continuum mechanics, as well as phenomenological thermodynamics, quantum mechanics and relativistic mechanics. Each chapter presents the basic physical facts of interest without going into details and derivations and without using advanced mathematical formalism. The first part constitutes a classical exposition of Lagrange's and Hamiltonian's analytical mechanics on which most of the continuum theory is based. The section on continuum mechanics focuses mainly on the axiomatic foundations, with many pointers for further research in this area. Special attention is given to modern continuum thermodynamics, both for the foundations and applications. A section on quantum mechanics is also included, since the phenomenological description of various quantum phenomena is becoming of increasing importance. refs.; figs.; tabs

Repeated exposures to roadside particulate matter extracts suppresses pulmonary defense mechanisms, resulting in lipid and protein oxidative damage.

Science.gov (United States)

Pardo, Michal; Porat, Ziv; Rudich, Assaf; Schauer, James J; Rudich, Yinon

2016-03-01

Exposure to particulate matter (PM) pollution in cities and urban canyons can be harmful to the exposed population. However, the underlying mechanisms that lead to health effects are not yet elucidated. It is postulated that exposure to repeated, small, environmentally relevant concentrations can affect lung homeostasis. This study examines the impact of repeated exposures to urban PM on mouse lungs with focus on inflammatory and oxidative stress parameters. Aqueous extracts from collected urban PM were administered to mice by 5 repeated intra-tracheal instillations (IT). Multiple exposures, led to an increase in cytokine levels in both bronchoalveolar lavage fluid and in the blood serum, indicating a systemic reaction. Lung mRNA levels of antioxidant/phase II detoxifying enzymes decreased by exposure to the PM extract, but not when metals were removed by chelation. Finally, disruption of lung tissue oxidant-inflammatory/defense balance was evidenced by increased levels of lipid and protein oxidation. Unlike response to a single IT exposure to the same dose and source of extract, multiple exposures result in lung oxidative damage and a systemic inflammatory reaction. These could be attributed to compromised capacity to activate the protective Nrf2 tissue defense system. It is suggested that water-soluble metals present in urban PM, potentially from break and tire wear, may constitute major drivers of the pulmonary and systemic responses to multiple exposure to urban PM. Copyright © 2015 Elsevier Ltd. All rights reserved.

Technology of Rock Destruction by Combined Explosion-Mechanical Load

Directory of Open Access Journals (Sweden)

Oleg M. Terentiev

2017-10-01

Full Text Available Background. Rock drilling is characterized by an energy capacity of more than 120 kWh/m3. This is due to the fact that about 90 % of the energy is expended on the “preparation” of rocks for destruction. This study proposes to combine explosive and mechanical loads to reduce specific energy consumption of rock destruction. Objective. The aim of the paper is energy effective technology development for rock destruction by combined explosive-mechanical loads. Methods. Analytical studies; regression analysis; math modeling; experimental research; technical and economic analysis. Results. Specific energy decreasing for explosive-mechanical rock drilling by 4–16 % was experimentally proved. Conclusions. As a result of the implementation of explosive-mechanical rock drilling on the created full-sized experimental device, the efficiency coefficient increased from 77 to 80 %.

Origami-inspired building block and parametric design for mechanical metamaterials

Science.gov (United States)

Jiang, Wei; Ma, Hua; Feng, Mingde; Yan, Leilei; Wang, Jiafu; Wang, Jun; Qu, Shaobo

2016-08-01

An origami-based building block of mechanical metamaterials is proposed and explained by introducing a mechanism model based on its geometry. According to our model, this origami mechanism supports response to uniaxial tension that depends on structure parameters. Hence, its mechanical properties can be tunable by adjusting the structure parameters. Experiments for poly lactic acid (PLA) samples were carried out, and the results are in good agreement with those of finite element analysis (FEA). This work may be useful for designing building blocks of mechanical metamaterials or other complex mechanical structures.

Origami-inspired building block and parametric design for mechanical metamaterials

International Nuclear Information System (INIS)

Jiang, Wei; Ma, Hua; Feng, Mingde; Yan, Leilei; Wang, Jiafu; Wang, Jun; Qu, Shaobo

2016-01-01

An origami-based building block of mechanical metamaterials is proposed and explained by introducing a mechanism model based on its geometry. According to our model, this origami mechanism supports response to uniaxial tension that depends on structure parameters. Hence, its mechanical properties can be tunable by adjusting the structure parameters. Experiments for poly lactic acid (PLA) samples were carried out, and the results are in good agreement with those of finite element analysis (FEA). This work may be useful for designing building blocks of mechanical metamaterials or other complex mechanical structures. (paper)

Mechanical characteristics of fully mechanized top-coal caving face and surrounding rock stress shell

Energy Technology Data Exchange (ETDEWEB)

Xie Guang-xiang [Anhui University of Science and Technology, Huainan (China)

2005-06-15

The distribution of surrounding rock stress in fully mechanized top-coal caving (FMTC) face was fully researched by large-scale and non-linear three-dimensional numerical simulation and equivalent laboratory. The results show that, there is the structure that is made of macroscopical stress shell composed of high stress binds in overlying strata of FMTC face. Stress shell, which bears and pass load of overlying strata, is primary supporting body. The stress in skewback of stress shell forms abutment pressure of surrounding rock in vicinity of working face. Bond-beam structure lies in reducing zone under stress shell. It only bear partial burden of strata under stress shell. The uppermost mechanical characteristic of FMTC face is lying in the low stress area under stress shell. It is the essential cause of strata behaviors of FMTC face relaxation. On the basis of analyzing stress shell, the mechanical essence that top coal performs a function of bedding is demonstrated. 4 refs., 7 figs.

Martensite and bainite in steels: transformation mechanism and mechanical properties

International Nuclear Information System (INIS)

Bhadeshia, H.K.D.H.

1997-01-01

Many essential properties of iron alloys depend on what actually happens when one allotropic form gives way to another, i.e. on the mechanism of phase change. The dependence of the mechanical properties on the atomic mechanism by which bainite and martensite grow is the focus of this paper. The discussion is illustrated in the context of some common engineering design parameters, and with a brief example of the inverse problem in which the mechanism may be a function of the mechanical properties. (orig.)

Size-dependent mechanical properties of 2D random nanofibre networks

International Nuclear Information System (INIS)

Lu, Zixing; Zhu, Man; Liu, Qiang

2014-01-01

The mechanical properties of nanofibre networks (NFNs) are size dependent with respect to different fibre diameters. In this paper, a continuum model is developed to reveal the size-dependent mechanical properties of 2D random NFNs. Since such size-dependent behaviours are attributed to different micromechanical mechanisms, the surface effects and the strain gradient (SG) effects are, respectively, introduced into the mechanical analysis of NFNs. Meanwhile, a modified fibre network model is proposed, in which the axial, bending and shearing deformations are incorporated. The closed-form expressions of effective modulus and Poisson's ratio are obtained for NFNs. Different from the results predicted by conventional fibre network model, the present model predicts the size-dependent mechanical properties of NFNs. It is found that both surface effects and SG effects have significant influences on the effective mechanical properties. Moreover, the present results show that the shearing deformation of fibre segment is also crucial to precisely evaluate the effective mechanical properties of NFNs. This work mainly aims to provide an insight into the micromechanical mechanisms of NFNs. Besides, this work is also expected to provide a more accurate theoretical model for 2D fibre networks. (paper)

Morphogengineering roots: comparing mechanisms of morphogen gradient formation

Science.gov (United States)

2012-01-01

Background In developmental biology, there has been a recent focus on the robustness of morphogen gradients as possible providers of positional information. It was shown that functional morphogen gradients present strong biophysical constraints and lack of robustness to noise. Here we explore how the details of the mechanism which underlies the generation of a morphogen gradient can influence those properties. Results We contrast three gradient-generating mechanisms, (i) a source-decay mechanism; and (ii) a unidirectional transport mechanism; and (iii) a so-called reflux-loop mechanism. Focusing on the dynamics of the phytohormone auxin in the root, we show that only the reflux-loop mechanism can generate a gradient that would be adequate to supply functional positional information for the Arabidopsis root, for biophysically reasonable kinetic parameters. Conclusions We argue that traits that differ in spatial and temporal time-scales can impose complex selective pressures on the mechanism of morphogen gradient formation used for the development of the particular organism. PMID:22583698

Imaging the Antikythera Mechanism

Energy Technology Data Exchange (ETDEWEB)

Malzbender, Thomas

2012-02-10

In 1900, a party of sponge divers chanced on the wreck of a Roman merchant vessel between Crete and mainland Greece. It was found to contain numerous ancient Greek treasures, among them a mysterious lump of clay that split open to reveal ‘mathematical gears’ as it dried out. This object is now known as the Antikythera Mechanism, one of the most enlightening artifacts in terms of revealing the advanced nature of ancient Greek science and technology. In 2005 we travelled to the National Archeological Museum in Athens to apply our Reflectance Imaging methods to the mechanism in the hopes of revealing ancient writing on the device. We were successful, and along with the results of Microfocus CT imaging, epigraphers were able to decipher 3000 characters.

Crude oil burning mechanisms

DEFF Research Database (Denmark)

van Gelderen, Laurens; Malmquist, L.M.V.; Jomaas, Grunde

2015-01-01

In order to improve predictions for the burning efficiency and the residue composition of in-situ burning of crude oil, the burning mechanism of crude oil was studied in relation to the composition of its hydrocarbon mixture, before, during and after the burning. The surface temperature, flame...... height, mass loss rate and residues of three hydrocarbon liquids (n-octane, dodecane and hexadecane), two crude oils (DUC and REBCO) and one hydrocarbon liquid mixture of the aforementioned hydrocarbon liquids were studied using the Crude Oil Flammability Apparatus. The experimental results were compared...... on the highest achievable oil slick temperature. Based on this mechanism, predictions can then be made depending on the hydrocarbon composition of the fuel and the measured surface temperature....

The mechanics of soft biological composites.

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Thao D. (Sandia National Laboratories, Livermore, CA); Grazier, John Mark; Boyce, Brad Lee; Jones, Reese E. (Sandia National Laboratories, Livermore, CA)

2007-10-01

Biological tissues are uniquely structured materials with technologically appealing properties. Soft tissues such as skin, are constructed from a composite of strong fibrils and fluid-like matrix components. This was the first coordinated experimental/modeling project at Sandia or in the open literature to consider the mechanics of micromechanically-based anisotropy and viscoelasticity of soft biological tissues. We have exploited and applied Sandia's expertise in experimentation and mechanics modeling to better elucidate the behavior of collagen fibril-reinforced soft tissues. The purpose of this project was to provide a detailed understanding of the deformation of ocular tissues, specifically the highly structured skin-like tissue in the cornea. This discovery improved our knowledge of soft/complex materials testing and modeling. It also provided insight into the way that cornea tissue is bio-engineered such that under physiologically-relevant conditions it has a unique set of properties which enhance functionality. These results also provide insight into how non-physiologic loading conditions, such as corrective surgeries, may push the cornea outside of its natural design window, resulting in unexpected non-linear responses. Furthermore, this project created a clearer understanding of the mechanics of soft tissues that could lead to bio-inspired materials, such as highly supple and impact resistant body armor, and improve our design of human-machine interfaces, such as micro-electrical-mechanical (MEMS) based prosthetics.

Mechanisms of vegetation-induced channel narrowing of an unregulated canyon river: Results from a natural field-scale experiment

Science.gov (United States)

Manners, Rebecca B.; Schmidt, John C.; Scott, Michael L.

2014-04-01

The lower Yampa River in Yampa Canyon, western Colorado serves as a natural, field-scale experiment, initiated when the invasive riparian plant, tamarisk (Tamarix spp.), colonized an unregulated river. In response to tamarisk's rapid invasion, the channel narrowed by 6% in the widest reaches since 1961. Taking advantage of this unique setting, we reconstructed the geomorphic and vegetation history in order to identify the key mechanisms for which, in the absence of other environmental perturbations, vegetation alters fluvial processes that result in a narrower channel. From our reconstruction, we identified a distinct similarity in the timing and magnitude of tamarisk encroachment and channel change, albeit with a lag in the channel response, thus suggesting tamarisk as the driving force. Within a decade of establishment, tamarisk effectively trapped sediment and, as a result, increased floodplain construction rates. Increasing tamarisk coverage over time also reduced the occurrence of floodplain stripping. Tamarisk recruitment was driven by both hydrologic and hydraulic variables, and the majority of tamarisk plants (84%) established below the stage of the 2-year flood. Thus, upon establishment nearly all plants regularly interact with the flow and sediment transport field. Our analyses were predicated on the hypothesis that the flow regime of the Yampa River was stationary, and that only the riparian vegetation community had changed. While not heavily impacted by water development, we determined that some aspects of the flow regime have shifted. However, this shift, which involved the clustering in time of extremely wet and dry years, did not influence fluvial processes directly. Instead these changes directly impacted riparian vegetation and changes in vegetation cover, in turn, altered fluvial processes. Today, the rate of channel change and new tamarisk recruitment is small. We believe that the rapid expansion of tamarisk and related floodplain construction

A Channel Allocation Mechanism for Cellular Networks

Directory of Open Access Journals (Sweden)

Chi-Hua Chen

2017-04-01

Full Text Available In cellular networks, call blocking causes lower customer satisfaction and economic loss. Therefore, the channel allocation for call block avoidance is an important issue. This study proposes a mechanism that considers the real-time traffic information (e.g., traffic flow and vehicle speed and the user behavior (e.g., call inter-arrival time and call holding time to analyze the adaptable number of communication calls in the specific cell for channel allocation. In experiments about call block probabilities (CBP, this study simulated two cases that are the situations of the whole day and traffic accident. The simulation results show that all CBPs in the scenario of whole day are less than 21.5% by using the proposed mechanism, which is better than using the static channel allocation (SCA mechanism. Moreover, all CBPs in the scenario of traffic accidents are less than 16.5% by using the proposed mechanism, which is better than using the SCA mechanism. Therefore, the proposed mechanism can decrease the number of CBPs effectively.

Mechanical transduction via a single soft polymer

Science.gov (United States)

Hou, Ruizheng; Wang, Nan; Bao, Weizhu; Wang, Zhisong

2018-04-01

Molecular machines from biology and nanotechnology often depend on soft structures to perform mechanical functions, but the underlying mechanisms and advantages or disadvantages over rigid structures are not fully understood. We report here a rigorous study of mechanical transduction along a single soft polymer based on exact solutions to the realistic three-dimensional wormlike-chain model and augmented with analytical relations derived from simpler polymer models. The results reveal surprisingly that a soft polymer with vanishingly small persistence length below a single chemical bond still transduces biased displacement and mechanical work up to practically significant amounts. This "soft" approach possesses unique advantages over the conventional wisdom of rigidity-based transduction, and potentially leads to a unified mechanism for effective allosterylike transduction and relay of mechanical actions, information, control, and molecules from one position to another in molecular devices and motors. This study also identifies an entropy limit unique to the soft transduction, and thereby suggests a possibility of detecting higher efficiency for kinesin motor and mutants in future experiments.

Intermittent, Non Cyclic Severe Mechanical Aortic Valve Regurgitation

Science.gov (United States)

Choi, Jong Hyun; Song, Seunghwan; Lee, Myung-Yong

2013-01-01

Mechanical aortic prosthesis dysfunction can result from thrombosis or pannus formation. We describe an unusual case of intermittent, non cyclic mechanical aortic prosthesis dysfunction due to pannus formation with thrombus in the absence of systolic restriction of disk excursion, that presented with intermittent severe aortic regurgitation. PMID:24459568

Mechanical Kinesiology.

Science.gov (United States)

Barham, Jerry N.

Mechanical kinesiology is defined as a study of the mechanical factors affecting human movement, i.e., applying the physical laws of mechanics to the study of human motor behavior. This textbook on the subject is divided into thirty lessons. Each lesson is organized into three parts: a part on the text proper; a part entitled "study…

Development of LTCC Materials with High Mechanical Strength

International Nuclear Information System (INIS)

Kawai, Shinya; Nishiura, Sousuke; Terashi, Yoshitake; Furuse, Tatsuji

2011-01-01

We have developed LTCC materials suitable for substrates of RF modules used in mobile phone. LTCC can provide excellent solutions to requirements of RF modules, such as down-sizing, embedded elements and high performance. It is also important that LTCC material has high mechanical strength to reduce risk of fracture by mechanical impact. We have established a method of material design for high mechanical strength. There are two successive steps in the concept to achieve high mechanical strength. The first step is to improve mechanical strength by increasing the Young's modulus, and the second step is either further improvement through the Young's modulus or enhancement of the fracture energy. The developed material, so called high-strength LTCC, thus possesses mechanical strength of 400MPa, which is twice as strong as conventional material whose mechanical strength is approximately 200MPa in typical. As a result, high-strength LTCC shows an excellent mechanical reliability, against the drop impact test for example. The paper presents material design and properties of LTCC materials.

Trends in applications of mathematics to mechanics

CERN Document Server

Stefanelli, Ulisse; Truskinovsky, Lev; Visintin, Augusto

2018-01-01

This volume originates from the INDAM Symposium on Trends on Applications of Mathematics to Mechanics (STAMM), which was held at the INDAM headquarters in Rome on 5–9 September 2016. It brings together original contributions at the interface of Mathematics and Mechanics. The focus is on mathematical models of phenomena issued from various applications. These include thermomechanics of solids and gases, nematic shells, thin films, dry friction, delamination, damage, and phase-field dynamics. The papers in the volume present novel results and identify possible future developments. The book is addressed to researchers involved in Mathematics and its applications to Mechanics.

On the dynamic mechanical property and deformation mechanism of as-extruded Mg-Sn-Ca alloys under tension

International Nuclear Information System (INIS)

Huang, Qiuyan; Pan, Hucheng; Tang, Aitao; Ren, Yuping; Song, Bo; Qin, Gaowu; Zhang, Mingxing; Pan, Fusheng

2016-01-01

To further understand the deformation mechanism of magnesium alloys and expand their applications under dynamic conditions, the newly developed Mg-2Sn-1Ca alloy (TX21) is selected as the representative sample and tested under wide loading rate ranging from quasi-static to dynamic level (10"−"3–500/s). Both ultimate tensile strength and elongation of the as-extruded TX21 alloys increase with strain rate. Although twinning is accompanied due to the enhanced activity at higher strain rate, the preferential activation of dislocations is readily clarified and confirmed as the dominant deformation modes. Active interactions of pyramidal dislocations result in the higher strain hardening ability and could be correlated to the obviously positive strain-rate sensitivity for mechanical properties. Moreover, it is observed that the larger grain size and higher content of solute atoms dissolved in matrix would lead to the more active dislocations and twinning formations. The present results would provide insight into further understanding the deformation mechanism under dynamic rate loading and designing Mg alloy suitable for impact conditions.

On the dynamic mechanical property and deformation mechanism of as-extruded Mg-Sn-Ca alloys under tension

Energy Technology Data Exchange (ETDEWEB)

Huang, Qiuyan [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Pan, Hucheng [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Tang, Aitao, E-mail: tat@cqu.edu.cn [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Ren, Yuping [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Song, Bo [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Qin, Gaowu, E-mail: qingw@smm.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Zhang, Mingxing [School of Mechanical and Mining Engineering, University of Queensland, St Lucia, QLD 4072 (Australia); Pan, Fusheng [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)

2016-05-10

To further understand the deformation mechanism of magnesium alloys and expand their applications under dynamic conditions, the newly developed Mg-2Sn-1Ca alloy (TX21) is selected as the representative sample and tested under wide loading rate ranging from quasi-static to dynamic level (10{sup −3}–500/s). Both ultimate tensile strength and elongation of the as-extruded TX21 alloys increase with strain rate. Although twinning is accompanied due to the enhanced activity at higher strain rate, the preferential activation of dislocations is readily clarified and confirmed as the dominant deformation modes. Active interactions of pyramidal dislocations result in the higher strain hardening ability and could be correlated to the obviously positive strain-rate sensitivity for mechanical properties. Moreover, it is observed that the larger grain size and higher content of solute atoms dissolved in matrix would lead to the more active dislocations and twinning formations. The present results would provide insight into further understanding the deformation mechanism under dynamic rate loading and designing Mg alloy suitable for impact conditions.

Negative hydrogen ion production mechanisms

Energy Technology Data Exchange (ETDEWEB)

Bacal, M. [UPMC, LPP, Ecole Polytechnique, UMR CNRS 7648, Palaiseau (France); Wada, M. [School of Science and Engineering, Doshisha University, Kyoto 610-0321 (Japan)

2015-06-15

Negative hydrogen/deuterium ions can be formed by processes occurring in the plasma volume and on surfaces facing the plasma. The principal mechanisms leading to the formation of these negative ions are dissociative electron attachment to ro-vibrationally excited hydrogen/deuterium molecules when the reaction takes place in the plasma volume, and the direct electron transfer from the low work function metal surface to the hydrogen/deuterium atoms when formation occurs on the surface. The existing theoretical models and reported experimental results on these two mechanisms are summarized. Performance of the negative hydrogen/deuterium ion sources that emerged from studies of these mechanisms is reviewed. Contemporary negative ion sources do not have negative ion production electrodes of original surface type sources but are operated with caesium with their structures nearly identical to volume production type sources. Reasons for enhanced negative ion current due to caesium addition to these sources are discussed.

Micro-mechanics based damage mechanics for 3D Orthogonal Woven Composites: Experiment and Numerical Modelling

KAUST Repository

Saleh, Mohamed Nasr; Lubineau, Gilles; Potluri, Prasad; Withers, Philip; Soutis, Constantinos

2016-01-01

Damage initiation and evolution of three-dimensional (3D) orthogonal woven carbon fibre composite (3DOWC) is investigated experimentally and numerically. Meso-scale homogenisation of the representative volume element (RVE) is utilised to predict the elastic properties, simulate damage initiation and evolution when loaded in tension. The effect of intra-yarns transverse cracking and shear diffused damage on the in-plane transverse modulus and shear modulus is investigated while one failure criterion is introduced to simulate the matrix damage. The proposed model is based on two major assumptions. First, the effect of the binder yarns, on the in-plane properties, is neglected, so the 3DOWC unit cell can be approximated as a (0o/90o) cross-ply laminate. Second, a micro-mechanics based damage approach is used at the meso-scale, so damage indicators can be correlated, explicitly, to the density of cracks within the material. Results from the simulated RVE are validated against experimental results along the warp (0o direction) and weft (90o direction). This approach paves the road for more predictive models as damage evolution laws are obtained from micro mechanical considerations and rely on few well-defined material parameters. This largely differs from classical damage mechanics approaches in which the evolution law is obtained by retrofitting experimental observations.

Micro-mechanics based damage mechanics for 3D Orthogonal Woven Composites: Experiment and Numerical Modelling

KAUST Repository

Saleh, Mohamed Nasr

2016-01-08

Damage initiation and evolution of three-dimensional (3D) orthogonal woven carbon fibre composite (3DOWC) is investigated experimentally and numerically. Meso-scale homogenisation of the representative volume element (RVE) is utilised to predict the elastic properties, simulate damage initiation and evolution when loaded in tension. The effect of intra-yarns transverse cracking and shear diffused damage on the in-plane transverse modulus and shear modulus is investigated while one failure criterion is introduced to simulate the matrix damage. The proposed model is based on two major assumptions. First, the effect of the binder yarns, on the in-plane properties, is neglected, so the 3DOWC unit cell can be approximated as a (0o/90o) cross-ply laminate. Second, a micro-mechanics based damage approach is used at the meso-scale, so damage indicators can be correlated, explicitly, to the density of cracks within the material. Results from the simulated RVE are validated against experimental results along the warp (0o direction) and weft (90o direction). This approach paves the road for more predictive models as damage evolution laws are obtained from micro mechanical considerations and rely on few well-defined material parameters. This largely differs from classical damage mechanics approaches in which the evolution law is obtained by retrofitting experimental observations.

Assessing learning outcomes in middle-division classical mechanics: The Colorado Classical Mechanics and Math Methods Instrument

Science.gov (United States)

Caballero, Marcos D.; Doughty, Leanne; Turnbull, Anna M.; Pepper, Rachel E.; Pollock, Steven J.

2017-06-01

Reliable and validated assessments of introductory physics have been instrumental in driving curricular and pedagogical reforms that lead to improved student learning. As part of an effort to systematically improve our sophomore-level classical mechanics and math methods course (CM 1) at CU Boulder, we have developed a tool to assess student learning of CM 1 concepts in the upper division. The Colorado Classical Mechanics and Math Methods Instrument (CCMI) builds on faculty consensus learning goals and systematic observations of student difficulties. The result is a 9-question open-ended post test that probes student learning in the first half of a two-semester classical mechanics and math methods sequence. In this paper, we describe the design and development of this instrument, its validation, and measurements made in classes at CU Boulder and elsewhere.

Extracontextuality and extravalence in quantum mechanics.

Science.gov (United States)

Auffèves, Alexia; Grangier, Philippe

2018-07-13

We develop the point of view where quantum mechanics results from the interplay between the quantized number of 'modalities' accessible to a quantum system, and the continuum of 'contexts' that are required to define these modalities. We point out the specific roles of 'extracontextuality' and 'extravalence' of modalities, and relate them to the Kochen-Specker and Gleason theorems.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'. © 2018 The Author(s).

Near-field NanoThermoMechanical memory

International Nuclear Information System (INIS)

Elzouka, Mahmoud; Ndao, Sidy

2014-01-01

In this letter, we introduce the concept of NanoThermoMechanical Memory. Unlike electronic memory, a NanoThermoMechanical memory device uses heat instead of electricity to record, store, and recover data. Memory function is achieved through the coupling of near-field thermal radiation and thermal expansion resulting in negative differential thermal resistance and thermal latching. Here, we demonstrate theoretically via numerical modeling the concept of near-field thermal radiation enabled negative differential thermal resistance that achieves bistable states. Design and implementation of a practical silicon based NanoThermoMechanical memory device are proposed along with a study of its dynamic response under write/read cycles. With more than 50% of the world's energy losses being in the form of heat along with the ever increasing need to develop computer technologies which can operate in harsh environments (e.g., very high temperatures), NanoThermoMechanical memory and logic devices may hold the answer

Statistical mechanics of solitons

International Nuclear Information System (INIS)

Bishop, A.

1980-01-01

The status of statistical mechanics theory (classical and quantum, statics and dynamics) is reviewed for 1-D soliton or solitary-wave-bearing systems. Primary attention is given to (i) perspective for existing results with evaluation and representative literature guide; (ii) motivation and status report for remaining problems; (iii) discussion of connections with other 1-D topics

43rd Aerospace Mechanisms Symposium

Science.gov (United States)

Boesiger, Edward A.

2016-01-01

The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production and use of aerospace mechanisms. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms. Sponsored and organized by the Mechanisms Education Association, responsibility for hosting the AMS is shared by the National Aeronautics and Space Administration and Lockheed Martin Space Systems Company (LMSSC). Now in its 43rd symposium, the AMS continues to be well attended, attracting participants from both the U.S. and abroad. The 43rd AMS was held in Santa Clara, California on May 4, 5 and 6, 2016. During these three days, 42 papers were presented. Topics included payload and positioning mechanisms, components such as hinges and motors, CubeSats, tribology, and mechanism testing. Hardware displays during the supplier exhibit gave attendees an opportunity to meet with developers of current and future mechanism components. The high quality of this symposium is a result of the work of many people, and their efforts are gratefully acknowledged. This extends to the voluntary members of the symposium organizing committee representing the eight NASA field centers, LMSSC, and the European Space Agency. Appreciation is also extended to the session chairs, the authors, and particularly the personnel at ARC responsible for the symposium arrangements and the publication of these proceedings. A sincere thank you also goes to the symposium executive committee who is responsible for the year-to-year management of the AMS, including paper processing and preparation of the program. The use of trade names of manufacturers in this publication does not constitute an official endorsement of such products or manufacturers, either expressed or implied, by the National Aeronautics and Space Administration.

Parallel inter channel interaction mechanisms

International Nuclear Information System (INIS)

Jovic, V.; Afgan, N.; Jovic, L.

1995-01-01

Parallel channels interactions are examined. For experimental researches of nonstationary regimes flow in three parallel vertical channels results of phenomenon analysis and mechanisms of parallel channel interaction for adiabatic condition of one-phase fluid and two-phase mixture flow are shown. (author)

Synthesis, Analysis And Simulation Of a Four-Bar Mechanism Using ...

African Journals Online (AJOL)

Kinematic synthesis of the four-bar mechanism using the complex number method is presented. The results of the synthesis process are analyzed to determine motion characteristics of the mechanism. These motion characteristics are then used for simulation of the mechanism. Matlab programs are written for solving the ...

Molecular mechanisms of cognitive dysfunction following traumatic brain injury

Science.gov (United States)

Walker, Kendall R.; Tesco, Giuseppina

2013-01-01

Traumatic brain injury (TBI) results in significant disability due to cognitive deficits particularly in attention, learning and memory, and higher-order executive functions. The role of TBI in chronic neurodegeneration and the development of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic Lateral Sclerosis (ALS) and most recently chronic traumatic encephalopathy (CTE) is of particular importance. However, despite significant effort very few therapeutic options exist to prevent or reverse cognitive impairment following TBI. In this review, we present experimental evidence of the known secondary injury mechanisms which contribute to neuronal cell loss, axonal injury, and synaptic dysfunction and hence cognitive impairment both acutely and chronically following TBI. In particular we focus on the mechanisms linking TBI to the development of two forms of dementia: AD and CTE. We provide evidence of potential molecular mechanisms involved in modulating Aβ and Tau following TBI and provide evidence of the role of these mechanisms in AD pathology. Additionally we propose a mechanism by which Aβ generated as a direct result of TBI is capable of exacerbating secondary injury mechanisms thereby establishing a neurotoxic cascade that leads to chronic neurodegeneration. PMID:23847533

Molecular mechanisms of cognitive dysfunction following traumatic brain injury.

Science.gov (United States)

Walker, Kendall R; Tesco, Giuseppina

2013-01-01

Traumatic brain injury (TBI) results in significant disability due to cognitive deficits particularly in attention, learning and memory, and higher-order executive functions. The role of TBI in chronic neurodegeneration and the development of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic Lateral Sclerosis (ALS) and most recently chronic traumatic encephalopathy (CTE) is of particular importance. However, despite significant effort very few therapeutic options exist to prevent or reverse cognitive impairment following TBI. In this review, we present experimental evidence of the known secondary injury mechanisms which contribute to neuronal cell loss, axonal injury, and synaptic dysfunction and hence cognitive impairment both acutely and chronically following TBI. In particular we focus on the mechanisms linking TBI to the development of two forms of dementia: AD and CTE. We provide evidence of potential molecular mechanisms involved in modulating Aβ and Tau following TBI and provide evidence of the role of these mechanisms in AD pathology. Additionally we propose a mechanism by which Aβ generated as a direct result of TBI is capable of exacerbating secondary injury mechanisms thereby establishing a neurotoxic cascade that leads to chronic neurodegeneration.

Mechanical Properties of Nanofilled Polypropylene Composites

Directory of Open Access Journals (Sweden)

Cristina-Elisabeta PELIN

2015-06-01

Full Text Available The paper presents a study concerning mechanical performance of thermoplastic nanocomposites based on isotactic polypropylene matrix, nanofilled with montmorillonite modified with quaternary ammonium salt and carboxyl functionalized carbon nanotubes, respectively, added in the same concentration relative to the matrix. The nanofilled and single polymer materials were obtained by simple melt compounding through extrusion process followed by injection molding into specific shape specimens for mechanical testing of the samples. Mechanical properties were evaluated by tensile and 3 point bending tests. In terms of modulus of elasticity, the results showed overall positive effects concerning the effect of nanofiller addition to the thermoplastic polymer. The fracture cross section of the tested specimens was characterized by FT-IR spectroscopy and SEM microscopy.

New Directions in Mathematical Fluid Mechanics

CERN Document Server

Fursikov, Andrei V

2010-01-01

The scientific interests of Professor A.V. Kazhikhov were fundamentally devoted to Mathematical Fluid Mechanics, where he achieved outstanding results that had, and still have, a significant influence on this field. This volume, dedicated to the memory of A.V. Kazhikhov, presents the latest contributions from renowned world specialists in a number of new important directions of Mathematical Physics, mostly of Mathematical Fluid Mechanics, and, more generally, in the field of nonlinear partial differential equations. These results are mostly related to boundary value problems and to control problems for the Navier-Stokes equations, and for equations of heat convection. Other important topics include non-equilibrium processes, Poisson-Boltzmann equations, dynamics of elastic body, and related problems of function theory and nonlinear analysis.

Enhancing medicine price transparency through price information mechanisms.

Science.gov (United States)

Hinsch, Michael; Kaddar, Miloud; Schmitt, Sarah

2014-05-08

Medicine price information mechanisms provide an essential tool to countries that seek a better understanding of product availability, market prices and price compositions of individual medicines. To be effective and contribute to cost savings, these mechanisms need to consider prices in their particular contexts when comparing between countries. This article discusses in what ways medicine price information mechanisms can contribute to increased price transparency and how this may affect access to medicines for developing countries. We used data collected during the course of a WHO project focusing on the development of a vaccine price and procurement information mechanism. The project collected information from six medicine price information mechanisms and interviewed data managers and technical experts on key aspects as well as observed market effects of these mechanisms.The reviewed mechanisms were broken down into categories including objective and target audience, as well as the sources, types and volumes of data included. Information provided by the mechanisms was reviewed according to data available on medicine prices, product characteristics, and procurement modalities. We found indications of positive effects on access to medicines resulting from the utilization of the reviewed mechanisms. These include the uptake of higher quality medicines, more favorable results from contract negotiations, changes in national pricing policies, and the decrease of prices in certain segments for countries participating in or deriving data from the various mechanisms. The reviewed mechanisms avoid the methodological challenges observed for medicine price comparisons that only use national price databases. They work with high quality data and display prices in the appropriate context of procurement modalities as well as the peculiarities of purchasing countries. Medicine price information mechanisms respond to the need for increased medicine price transparency and have the

Microstructure, mechanical and tribological behavior of hot-pressed mechanically alloyed Al–Zn–Mg–Cu powders

International Nuclear Information System (INIS)

Azimi, A.; Fallahdoost, H.; Nejadseyfi, O.

2015-01-01

Highlights: • Nanocrystalline Al7050 alloy was synthesized by mechanical alloying. • Longer milling time led to increasing porosity in hot-pressed samples. • Significant improvement in strength and wear resistance was obtained by increasing the milling time up to 40 h. - Abstract: This research focuses on the preparation of Al7050 alloy via mechanical alloying and hot pressing techniques. The effect of milling time on the microstructure and densification response was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). Furthermore, the mechanical properties of the samples including microhardness, compression strength, and wear resistance were examined as a function of milling time. The results of the experiments proved that by increasing the milling time the crystallite size was reduced, which has a significant effect on improving the mechanical properties. In addition, porosity formation increased when the milling time was increased due to reduction of the compressibility of finer particles. By increasing the milling time to more than 40 h, a relatively invariable crystallite size was obtained and it was observed that the porosities expanded in the samples. Therefore, the compressive strength, hardness, and wear resistance were enhanced up to 40 h milling time and then the strengthening effect was relatively diminished. On observing surfaces with SEM, the dominant wear mechanism was recognized as abrasion, delamination and adhesion

The influence of electric charge transferred during electro-mechanical reshaping on mechanical behavior of cartilage

Science.gov (United States)

Protsenko, Dimitry E.; Lim, Amanda; Wu, Edward C.; Manuel, Cyrus; Wong, Brian J. F.

2011-03-01

Electromechanical reshaping (EMR) of cartilage has been suggested as an alternative to the classical surgical techniques of modifying the shape of facial cartilages. The method is based on exposure of mechanically deformed cartilaginous tissue to a low level electric field. Electro-chemical reactions within the tissue lead to reduction of internal stress, and establishment of a new equilibrium shape. The same reactions offset the electric charge balance between collagen and proteoglycan matrix and interstitial fluid responsible for maintenance of cartilage mechanical properties. The objective of this study was to investigate correlation between the electric charge transferred during EMR and equilibrium elastic modulus. We used a finite element model based on the triphasic theory of cartilage mechanical properties to study how electric charges transferred in the electro-chemical reactions in cartilage can change its mechanical responses to step displacements in unconfined compression. The concentrations of the ions, the strain field and the fluid and ion velocities within the specimen subject to an applied mechanical deformation were estimated and apparent elastic modulus (the ratio of the equilibrium axial stress to the axial strain) was calculated as a function of transferred charge. The results from numerical calculations showed that the apparent elastic modulus decreases with increase in electric charge transfer. To compare numerical model with experimental observation we measured elastic modulus of cartilage as a function of electric charge transferred in electric circuit during EMR. Good correlation between experimental and theoretical data suggests that electric charge disbalance is responsible for alteration of cartilage mechanical properties.

Magnetization reversal mechanisms under oblique magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Ntallis, N.; Efthimiadis, K.G., E-mail: kge@auth.gr

2017-03-01

In this work finite element micromagnetic simulations were performed in order to study the reversal mechanisms of spherical ferromagnetic particles with uniaxial magnetocrystalline anisotropy, when they are magnetized along an oblique direction with respect to the anisotropy axis. Magnetization loops are taken in different directions of external magnetic field, at different anisotropy constants and particle sizes. In the simulation results, the three reversal mechanisms (coherent, curling and domains) are observed and new phenomena arise due to the action of oblique magnetic fields. Moreover, the dependence of the critical fields with respect to the angle of the external field is presented. - Highlights: • Finite element micromagnetic simulation of the three different reversal mechanisms. • For the curling mechanism, the new phenomenon is the rotation of the vortex. • In the domain reversal mechanism, the formed domain wall is smaller than 180°. • In soft ferromagnetic particles a rearrangement of the magnetic domains is observed.

Can quantum mechanics fool the cosmic censor?

International Nuclear Information System (INIS)

Matsas, G. E. A.; Silva, A. R. R. da; Richartz, M.; Saa, A.; Vanzella, D. A. T.

2009-01-01

We revisit the mechanism for violating the weak cosmic-censorship conjecture (WCCC) by overspinning a nearly-extreme charged black hole. The mechanism consists of an incoming massless neutral scalar particle, with low energy and large angular momentum, tunneling into the hole. We investigate the effect of the large angular momentum of the incoming particle on the background geometry and address recent claims that such a backreaction would invalidate the mechanism. We show that the large angular momentum of the incident particle does not constitute an obvious impediment to the success of the overspinning quantum mechanism, although the induced backreaction turns out to be essential to restoring the validity of the WCCC in the classical regime. These results seem to endorse the view that the 'cosmic censor' may be oblivious to processes involving quantum effects.

Generation of Articulated Mechanisms by Optimization Techniques

DEFF Research Database (Denmark)

Kawamoto, Atsushi

2004-01-01

optimization [Paper 2] 3. Branch and bound global optimization [Paper 3] 4. Path-generation problems [Paper 4] In terms of the objective of the articulated mechanism design problems, the first to third papers deal with maximization of output displacement, while the fourth paper solves prescribed path...... generation problems. From a mathematical programming point of view, the methods proposed in the first and third papers are categorized as deterministic global optimization, while those of the second and fourth papers are categorized as gradient-based local optimization. With respect to design variables, only...... directly affects the result of the associated sensitivity analysis. Another critical issue for mechanism design is the concept of mechanical degrees of freedom and this should be also considered for obtaining a proper articulated mechanism. The thesis treats this inherently discrete criterion in some...

Ultrahigh-Q mechanical oscillators through optical trapping

International Nuclear Information System (INIS)

Chang, D E; Ni, K-K; Painter, O; Kimble, H J

2012-01-01

Rapid advances are being made toward optically cooling a single mode of a micro-mechanical system to its quantum ground state and observing the quantum behavior at macroscopic scales. Reaching this regime in room-temperature environments requires a stringent condition on the mechanical quality factor Q m and frequency f m , Q m f m ≳ k B T bath /h, which so far has been marginally satisfied only in a small number of systems. Here we propose and analyze a new class of systems that should enable one to obtain unprecedented Q-frequency products. The technique is based on the use of optical forces to ‘trap’ and stiffen the motion of a tethered mechanical structure, thereby freeing the resulting mechanical frequencies and decoherence rates from the underlying material properties. (paper)

Thiol-ene/methacrylate systems for mechanical damping

Science.gov (United States)

McNair, Olivia; Senyurt, Askim; Wei, Huanyu; Gould, Trent; Piland, Scott; Hoyle, Charles; Savin, Daniel

2010-03-01

Ternary thiol-ene-methacrylate (TEMA) networks as materials for mechanical energy damping are unique to the sports world. Using a photoinitiation process, TEMA systems are formed via an initial thiol-ene step-growth mechanism along with traditional radical polymerization of acrylate and ene monomers. Final networks have two-part morphologies: acrylate homopolymer sectors imbedded in a multi-component mesh. Several (TEMA) systems have been synthesized and analyzed via thermal and mechanical probing. Initial studies on these ternary systems have shown excellent properties compared to traditional ethylene vinyl alcohol (EVA) copolymers. For example, PEMA networks exhibit glass transition temperatures 33 K higher than EVA, resulting in improved damping at room temperature. This research will help develop relationships between tan delta, glass transition and their effects on mechanical energy damping for ternary (TEMA) systems.

Analysis of Heat Generation Mechanism in Ultrasound Infrared Thermography

International Nuclear Information System (INIS)

Choi, Man Yong; Lee, Seung Seok; Park, Jeong Hak; Kang, Ki Soo; Kim, Won Tae

2009-01-01

Heat generation mechanism of ultrasound infrared thermography is still not well understood, yet and there are two reliable assumptions of heat generation, friction and thermo-mechanical effect. This paper investigates the principal cause of heat generation at fatigue crack with experimental and numerical approach. Our results show most of heat generation is contributed by friction between crack interface and thermo-mechanical effect is a negligible quantity

Lithium concentration dependent structure and mechanics of amorphous silicon

Energy Technology Data Exchange (ETDEWEB)

Sitinamaluwa, H. S.; Wang, M. C.; Will, G.; Senadeera, W.; Yan, C., E-mail: c2.yan@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), Brisbane QLD 4001 (Australia); Zhang, S. [Centre for Clean Environment and Energy, Environmental Futures Research Institute and Griffith School of Environment, Gold Coast Campus, Griffith University, QLD 4222 (Australia)

2016-06-28

A better understanding of lithium-silicon alloying mechanisms and associated mechanical behavior is essential for the design of Si-based electrodes for Li-ion batteries. Unfortunately, the relationship between the dynamic mechanical response and microstructure evolution during lithiation and delithiation has not been well understood. We use molecular dynamic simulations to investigate lithiated amorphous silicon with a focus to the evolution of its microstructure, phase composition, and stress generation. The results show that the formation of Li{sub x}Si alloy phase is via different mechanisms, depending on Li concentration. In these alloy phases, the increase in Li concentration results in reduction of modulus of elasticity and fracture strength but increase in ductility in tension. For a Li{sub x}Si system with uniform Li distribution, volume change induced stress is well below the fracture strength in tension.

College mechanics

CERN Document Server

Şengül, Caner

2016-01-01

College Mechanics QueBank has been designed to be different, enthusiastic, interesting and helpful to you. Therefore, it is not just a test bank about mechanics but also it is like a compass in order to find your way in mechanics Each chapter in this book is put in an order to follow a hierarchy of the mechanics topics; from vectors to simple harmonic motion. Throughout the book there are many multiple choice and long answer questions for you to solve. They have been created for YGS, LYS, SAT, IB or other standardized exams in the world because mechanics has no boundaries and so Physics has no country. Learn the main principle of each chapter and explore the daily life applications. Then you can start to solve the questions by planning a problem solving method carefully. Finally, enjoy solving the questions and discover the meachanics of the universe once more.

A Practical Quantum Mechanics Molecular Mechanics Method for the Dynamical Study of Reactions in Biomolecules.

Science.gov (United States)

Mendieta-Moreno, Jesús I; Marcos-Alcalde, Iñigo; Trabada, Daniel G; Gómez-Puertas, Paulino; Ortega, José; Mendieta, Jesús

2015-01-01

Quantum mechanics/molecular mechanics (QM/MM) methods are excellent tools for the modeling of biomolecular reactions. Recently, we have implemented a new QM/MM method (Fireball/Amber), which combines an efficient density functional theory method (Fireball) and a well-recognized molecular dynamics package (Amber), offering an excellent balance between accuracy and sampling capabilities. Here, we present a detailed explanation of the Fireball method and Fireball/Amber implementation. We also discuss how this tool can be used to analyze reactions in biomolecules using steered molecular dynamics simulations. The potential of this approach is shown by the analysis of a reaction catalyzed by the enzyme triose-phosphate isomerase (TIM). The conformational space and energetic landscape for this reaction are analyzed without a priori assumptions about the protonation states of the different residues during the reaction. The results offer a detailed description of the reaction and reveal some new features of the catalytic mechanism. In particular, we find a new reaction mechanism that is characterized by the intramolecular proton transfer from O1 to O2 and the simultaneous proton transfer from Glu 165 to C2. Copyright © 2015 Elsevier Inc. All rights reserved.

Search Results | Page 35 | IDRC - International Development ...

International Development Research Centre (IDRC) Digital Library (Canada)

Results 341 - 350 of 8490 ... Understanding the biological mechanisms of Zika virus disease ... Preventing Zika disease with novel vector control approaches ... have also faced outbreaks of chikungunya (2014-2015) and Zika (2015-2016).

Fracture Mechanics Analyses of Subsurface Defects in Reinforced Carbon-Carbon Joggles Subjected to Thermo-Mechanical Loads

Science.gov (United States)

Knight, Norman F., Jr.; Raju, Ivatury S.; Song, Kyongchan

2011-01-01

Coating spallation events have been observed along the slip-side joggle region of the Space Shuttle Orbiter wing-leading-edge panels. One potential contributor to the spallation event is a pressure build up within subsurface voids or defects due to volatiles or water vapor entrapped during fabrication, refurbishment, or normal operational use. The influence of entrapped pressure on the thermo-mechanical fracture-mechanics response of reinforced carbon-carbon with subsurface defects is studied. Plane-strain simulations with embedded subsurface defects are performed to characterize the fracture mechanics response for a given defect length when subjected to combined elevated-temperature and subsurface-defect pressure loadings to simulate the unvented defect condition. Various subsurface defect locations of a fixed-length substrate defect are examined for elevated temperature conditions. Fracture mechanics results suggest that entrapped pressure combined with local elevated temperatures have the potential to cause subsurface defect growth and possibly contribute to further material separation or even spallation. For this anomaly to occur, several unusual circumstances would be required making such an outcome unlikely but plausible.

XXII Fluid Mechanics Conference (KKMP2016)

International Nuclear Information System (INIS)

2016-01-01

This Journal of Physics: Conference Series contains papers that have been presented at XXII Fluid Mechanics Conference (XXII FMC) held in Słok near Bełchatów in Poland during llth-14th September of 2016. The Conference is organized by Wrocław University of Science and Technology, Polish Academy of Sciences - Committee of Mechanics and Foun-dation for Development of Wroclaw University of Science and Technology. Let us recall some historical facts: Fluid Mechanics Conferences have been taking place every two years since 1974, which makes a total of forty-two years. The goal of this conference is to provide a forum for exposure and exchange of ideas, methods and results in fluid mechanics. We have already met in Bełchatów 10 years ago (XVII KKMP). It was a successful meeting. Since then the National Conference on Fluid Mechanics has changed title and has started to be named Fluid Mechanics Conference in the hopes that it will attract more participants from other countries. English became the Conference's first language and we started to invite world leading scientists - working in the field of fluid mechanics. At the 2006 conference we hosted for the first time prof. Keith Moffatt from the Cambridge University. In this year prof. Moffatt once again promised us to arrive to Bełchatów. The whole fluid mechanics community celebrates 9 2 anniversary of his birthday. So let us also wish happy anniversary to prof. Moffatt. In the mean time we had to pay last respects to our collages. Prof. Prosnak who is regarded as a founder of the Notational Conference on Fluid Mechanics and is well known through his books. Prof. Puzyrewski who was present at all conferences so far. He was providing via his discussions a special value to these conferences, and our colleague prof. Konrad Bajer who was intended to be the organizer and host of the present conference. Short memories to them will be given during the opening ceremony. Conference topics include, but are not limited

Intermittent, noncyclic dysfunction of a mechanical aortic prosthesis by pannus formation.

Science.gov (United States)

Giroux, Sylvie K; Labinaz, Marino X; Grisoli, Dominique; Klug, Andrew P; Veinot, John P; Burwash, Ian G

2010-01-01

Mechanical aortic prosthesis dysfunction can result from thrombosis or pannus formation. Pannus formation usually restricts systolic excursion of the occluding disk, resulting in progressive stenosis of the aortic prosthesis. Intermittent dysfunction of a mechanical aortic prosthesis is usually ascribed to thrombus formation. We describe an unusual case of intermittent, noncyclic dysfunction of a mechanical aortic prosthesis due to pannus formation in the absence of systolic restriction of disk excursion that presented with intermittent massive aortic regurgitation, severe ischemia, and shock. Pannus formation should be considered as a potential cause of acute intermittent severe aortic regurgitation in a patient with a mechanical aortic prosthesis.

A linear chromatic mechanism drives the pupillary response.

Science.gov (United States)

Tsujimura, S.; Wolffsohn, J. S.; Gilmartin, B.

2001-01-01

Previous studies have shown that a chromatic mechanism can drive pupil responses. The aim of this research was to clarify whether a linear or nonlinear chromatic mechanism drives pupillary responses by using test stimuli of various colours that are defined in cone contrast space. The pupil and accommodation responses evoked by these test stimuli were continuously and simultaneously objectively measured by photorefraction. The results with isochromatic and isoluminant stimuli showed that the accommodative level remained approximately constant (< 0.25 D change in mean level) even when the concurrent pupillary response was large (ca. 0.30 mm). The pupillary response to an isoluminant grating was sustained, delayed (by ca. 60 ms) and larger in amplitude than that for a isochromatic uniform stimulus, which supports previous work suggesting that the chromatic mechanism contributes to the pupillary response. In a second experiment, selected chromatic test gratings were used and isoresponse contours in cone contrast space were obtained. The results showed that the isoresponse contour in cone contrast space is well described (r(2) = 0.99) by a straight line with a positive slope. The results indicate that a /L - M/ linear chromatic mechanism, whereby a signal from the long wavelength cone is subtracted from that of the middle wavelength cone and vice versa, drives pupillary responses. PMID:11674867

Multi-channel mechanical test machine for HANARO (I)

International Nuclear Information System (INIS)

Song, M. S.; Choi, Y.; Cho, M. S.; Kim, B. G.; Kang, Y. H.

2004-01-01

Design and fabrication of multi-channel mechanical test machine is useful and important for the study of in-pile test of nuclear materials in HANARO. The dimension and shape of the multi-channel mechanical test machine should be fixed to a test reactor and their objectives. KAERI successfully developed a non-instrumented multi-channel mechanical test machine for material irradiation tests in a domestic research reactor, HANARO. This results in strongly stimulating and accelerating irradiation tests of materials in domestic industry and research fields with HANARO. Although various types of in-pile creep capsule were made for well installation in each test reactor, there is no in-pile creep multi-channel mechanical test machine for HANARO. Hence, the objectives of this study are to fabricate and test a multi-channel mechanical test machine of HANARO

Statistical algebraic approach to quantum mechanics

International Nuclear Information System (INIS)

Slavnov, D.A.

2001-01-01

The scheme for plotting the quantum theory with application of the statistical algebraic approach is proposed. The noncommutative algebra elements (observed ones) and nonlinear functionals on this algebra (physical state) are used as the primary constituents. The latter ones are associated with the single-unit measurement results. Certain physical state groups are proposed to consider as quantum states of the standard quantum mechanics. It is shown that the mathematical apparatus of the standard quantum mechanics may be reproduced in such a scheme in full volume [ru

Results of Monitoring at Olkiluoto in 2007. Rock Mechanics

International Nuclear Information System (INIS)

Mattila, J.; Hakala, M.

2008-06-01

Posiva Oy has operated a local microseismic at Olkiluoto network since February 2002. During the monitoring in 2007, altogether 2207 events have been located in the Olkiluoto area, in the reported time period. The magnitudes of the observed events range from ML = -2.1 to 1.5 (ML = magnitude in local Richter's scale). All these events are explosions. Evidence of seismic activity that would have influence on the safety of the ONKALO, have not been observed. One recorded event was a microearthquake of magnitude ML 1.9, which occurred in Laitila, approximately 40 km from Olkiluoto. The GPS based deformation studies have been made at the investigation areas of Posiva since 1995, when the network of ten GPS pillars was established at Olkiluoto. Since then, altogether 24 GPS measurement campaigns have been carried out at Olkiluoto. According to the time series of the GPS results, 1/3 of the baselines at Olkiluoto have statistically significant change rates. However, the observed movements are smaller than ± 0.20 mm/a. There are five pillars, which have statistically significant horizontal velocities at Olkiluoto. These local velocity components are small but taking into account the standard deviations the largest velocity components seems to be reliably determined (maximum velocity is -0.21 mm/a ± 0.02 mm/a) In order to monitor vertical movements at Olkiluoto, precise leveling campaigns of the GPS stations were started in the area in autumn 2003. Since then, leveling campaigns have taken place in 2005 and 2007, including the leveling of the existing GPS network and line from Olkiluoto Island to Lapijoki at the main land. Additional smaller leveling campaigns took place in 2006. The campaign in autumn 2007 consisted of the levellings of all measured and undestroyed points of the earlier campaigns. Compared to the mean theoretical land uplift, the nodal bench mark near the crossing of Olkiluodontie and Satamatie had risen in four years 2.6 mm more than the nodal bench

Search Results | Page 4 | IDRC - International Development ...

International Development Research Centre (IDRC) Digital Library (Canada)

Results 31 - 40 of 9603 ... Journal articles ... Pro-poor watershed functions : agroforestrees at the right place and time, negotiations and reward mechanisms ... Community - Based Upland Natural Resources Management in A Luoi, Thua Thien ...

A model of mechanical interactions between heart and lungs.

Science.gov (United States)

Fontecave Jallon, Julie; Abdulhay, Enas; Calabrese, Pascale; Baconnier, Pierre; Gumery, Pierre-Yves

2009-12-13

To study the mechanical interactions between heart, lungs and thorax, we propose a mathematical model combining a ventilatory neuromuscular model and a model of the cardiovascular system, as described by Smith et al. (Smith, Chase, Nokes, Shaw & Wake 2004 Med. Eng. Phys.26, 131-139. (doi:10.1016/j.medengphy.2003.10.001)). The respiratory model has been adapted from Thibault et al. (Thibault, Heyer, Benchetrit & Baconnier 2002 Acta Biotheor. 50, 269-279. (doi:10.1023/A:1022616701863)); using a Liénard oscillator, it allows the activity of the respiratory centres, the respiratory muscles and rib cage internal mechanics to be simulated. The minimal haemodynamic system model of Smith includes the heart, as well as the pulmonary and systemic circulation systems. These two modules interact mechanically by means of the pleural pressure, calculated in the mechanical respiratory system, and the intrathoracic blood volume, calculated in the cardiovascular model. The simulation by the proposed model provides results, first, close to experimental data, second, in agreement with the literature results and, finally, highlighting the presence of mechanical cardiorespiratory interactions.

Resonance charge exchange mechanism at high and moderate energies

International Nuclear Information System (INIS)

Bogdanov, A.V.; Gevorkyan, A.S.

1984-01-01

Charge exchange mechanisms at high and medium energies are investigated, ta king the resonance charge exchange of a proton by an hydrogen atom as an example . It is established that there are two classical charge exchange mechanisms rel ated to direct proton knockout from the bound state and one quantum-mechanical mechanism corresponding to the electron tunnelling from one bound state to anoth er. The classical cross-section diverges for two of these mechanisms, and the quasiclassical scattering amplitude must be calculated on the base of a complex classical trajectory. Physical grounds for the choice of such trajectories are discussed and calculations of the Van Vleck determinant for these mechanisms a re presented. Contributions from different mechanisms to the total charge excha nge cross-section are analyzed. A comparison with experimental data and results of other authors is made

Fracture mechanics and microstructures

International Nuclear Information System (INIS)

Gee, M.G.; Morrell, R.

1986-01-01

The influence of microstructure on defects in ceramics, and the consequences of their presence for the application of fracture mechanics theories are reviewed. The complexities of microstructures, especially the multiphase nature, the crystallographic anisotropy and the resultant anisotropic physical properties, and the variation of microstructure and surface finish from point to point in real components, all lead to considerable uncertainties in the actual performance of any particular component. It is concluded that although the concepts of fracture mechanics have been and will continue to be most useful for the qualitative explanation of fracture phenomena, the usefulness as a predictive tool with respect to most existing types of material is limited by the interrelation between material microstructure and mechanical properties. At present, the only method of eliminating components with unsatisfactory mechanical properties is to proof-test them, despite the fact that proof-testing itself is limited in ability to cope with changes to the component in service. The aim of the manufacturer must be to improve quality and consistency within individual components, from component to component, and from batch to batch. The aim of the fracture specialist must be to study longer-term properties to improve the accuracy of behaviour predictions with a stronger data base. Materials development needs to concentrate on obtaining defect-free materials that can be translated into more-reliable products, using our present understanding of the influence of microstructure on strength and toughness

Scattering in relativistic particle mechanics

International Nuclear Information System (INIS)

De Bievre, S.

1986-01-01

The problem of direct interaction in relativistic particle mechanics has been extensively studied and a variety of models has been proposed avoiding the conclusions of the so-called no-interaction theorems. In this thesis the authors studied scattering in the relativistic two-body problem. He uses the results to analyze gauge invariance in Hamiltonian constraint models and the uniqueness of the symplectic structure in manifestly covariant relativistic particle mechanics. A general geometric framework that underlies approaches to relativistic particle mechanics is presented and the kinematic properties of the scattering transformation, i.e., those properties that arise solely from the invariance of the theory under the Poincare group are studied. The second part of the analysis of the relativistic two-body scattering problem is devoted to the dynamical properties of the scattering process. Using general geometric arguments, gauge invariance of the scattering transformation in the Todorov-Komar Hamiltonian constraint model is proved. Finally, quantization of the models is discussed

Mechanisms of radioprotection - a review

International Nuclear Information System (INIS)

Copeland, E.S.

1978-01-01

Theories of radiation protection can be considered at both the molecular and biochemical-physiological levels. Four molecular level protection hypotheses, radical scavenging, hydrogen transfer reactions, the mixed disulfide hypothesis and the endogenous non-protein sulfhydryl hypothesis, probably describe different aspects of the actual protection mechanism, although each has inconsistencies. At the biochemical-physiological level, hypothermia induction and biochemical shock may be involved in protection of the organism against radiation induced damage and death. It is most likely that no single mechanism can account for the protection offered by a radioprotective drug. Certain compounds may operate primarily by means of physiological effects resulting in hypoxia or hypothermia in critical tissues. Others may operate primarily by influencing the intrinsic radiosensitivity of target molecules by causing localized radical scavenging or by donating a hydrogen atom. Metabolic effects such as biochemical shock, release of endogenous non-protein sulfhydryls, induction of structural changes in target molecules or delay in DNA synthesis and cell division are also possible mechanisms for radioprotection. (author)

The large deviation approach to statistical mechanics

International Nuclear Information System (INIS)

Touchette, Hugo

2009-01-01

The theory of large deviations is concerned with the exponential decay of probabilities of large fluctuations in random systems. These probabilities are important in many fields of study, including statistics, finance, and engineering, as they often yield valuable information about the large fluctuations of a random system around its most probable state or trajectory. In the context of equilibrium statistical mechanics, the theory of large deviations provides exponential-order estimates of probabilities that refine and generalize Einstein's theory of fluctuations. This review explores this and other connections between large deviation theory and statistical mechanics, in an effort to show that the mathematical language of statistical mechanics is the language of large deviation theory. The first part of the review presents the basics of large deviation theory, and works out many of its classical applications related to sums of random variables and Markov processes. The second part goes through many problems and results of statistical mechanics, and shows how these can be formulated and derived within the context of large deviation theory. The problems and results treated cover a wide range of physical systems, including equilibrium many-particle systems, noise-perturbed dynamics, nonequilibrium systems, as well as multifractals, disordered systems, and chaotic systems. This review also covers many fundamental aspects of statistical mechanics, such as the derivation of variational principles characterizing equilibrium and nonequilibrium states, the breaking of the Legendre transform for nonconcave entropies, and the characterization of nonequilibrium fluctuations through fluctuation relations.

The large deviation approach to statistical mechanics

Science.gov (United States)

Touchette, Hugo

2009-07-01

The theory of large deviations is concerned with the exponential decay of probabilities of large fluctuations in random systems. These probabilities are important in many fields of study, including statistics, finance, and engineering, as they often yield valuable information about the large fluctuations of a random system around its most probable state or trajectory. In the context of equilibrium statistical mechanics, the theory of large deviations provides exponential-order estimates of probabilities that refine and generalize Einstein’s theory of fluctuations. This review explores this and other connections between large deviation theory and statistical mechanics, in an effort to show that the mathematical language of statistical mechanics is the language of large deviation theory. The first part of the review presents the basics of large deviation theory, and works out many of its classical applications related to sums of random variables and Markov processes. The second part goes through many problems and results of statistical mechanics, and shows how these can be formulated and derived within the context of large deviation theory. The problems and results treated cover a wide range of physical systems, including equilibrium many-particle systems, noise-perturbed dynamics, nonequilibrium systems, as well as multifractals, disordered systems, and chaotic systems. This review also covers many fundamental aspects of statistical mechanics, such as the derivation of variational principles characterizing equilibrium and nonequilibrium states, the breaking of the Legendre transform for nonconcave entropies, and the characterization of nonequilibrium fluctuations through fluctuation relations.

Non-strictly black body spectrum from the tunnelling mechanism

International Nuclear Information System (INIS)

Corda, Christian

2013-01-01

The tunnelling mechanism is widely used to explain Hawking radiation. However, in many cases the analysis used to obtain the Hawking temperature only involves comparing the emission probability for an outgoing particle with the Boltzmann factor. Banerjee and Majhi improved this approach by explicitly finding a black body spectrum associated with black holes. Their result, obtained using a reformulation of the tunnelling mechanism, is in contrast to that of Parikh and Wilczek, who found an emission probability that is compatible with a non-strictly thermal spectrum. Using the recently identified effective state for a black hole, we solve this contradiction via a slight modification of the analysis by Banerjee and Majhi. The final result is a non-strictly black body spectrum from the tunnelling mechanism. We also show that for an effective temperature, we can express the corresponding effective metric using Hawking’s periodicity arguments. Potential important implications for the black hole information puzzle are discussed. -- Highlights: •We review an important result by Banerjee and Majhi on the tunnelling mechanism in the framework of Hawking radiation. •This result is in contrast to another result reported by Parikh and Wilczek. •We introduce the effective state of a black hole. •We explain the contrast via a slight modification of the analysis by Banerjee and Majhi. •We discuss potential important implications for the black hole information puzzle

Respiratory mechanics