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Sample records for high mechanical advantage

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

    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.

  2. Comparative advantages of mechanical biosensors.

    Arlett, J L; Myers, E B; Roukes, M L

    2011-04-01

    Mechanical interactions are fundamental to biology. Mechanical forces of chemical origin determine motility and adhesion on the cellular scale, and govern transport and affinity on the molecular scale. Biological sensing in the mechanical domain provides unique opportunities to measure forces, displacements and mass changes from cellular and subcellular processes. Nanomechanical systems are particularly well matched in size with molecular interactions, and provide a basis for biological probes with single-molecule sensitivity. Here we review micro- and nanoscale biosensors, with a particular focus on fast mechanical biosensing in fluid by mass- and force-based methods, and the challenges presented by non-specific interactions. We explain the general issues that will be critical to the success of any type of next-generation mechanical biosensor, such as the need to improve intrinsic device performance, fabrication reproducibility and system integration. We also discuss the need for a greater understanding of analyte-sensor interactions on the nanoscale and of stochastic processes in the sensing environment.

  3. Provably unbounded memory advantage in stochastic simulation using quantum mechanics

    Garner, Andrew J. P.; Liu, Qing; Thompson, Jayne; Vedral, Vlatko; Gu, mile

    2017-10-01

    Simulating the stochastic evolution of real quantities on a digital computer requires a trade-off between the precision to which these quantities are approximated, and the memory required to store them. The statistical accuracy of the simulation is thus generally limited by the internal memory available to the simulator. Here, using tools from computational mechanics, we show that quantum processors with a fixed finite memory can simulate stochastic processes of real variables to arbitrarily high precision. This demonstrates a provable, unbounded memory advantage that a quantum simulator can exhibit over its best possible classical counterpart.

  4. Provably unbounded memory advantage in stochastic simulation using quantum mechanics

    Garner, Andrew J P; Thompson, Jayne; Vedral, Vlatko; Gu, Mile; Liu, Qing

    2017-01-01

    Simulating the stochastic evolution of real quantities on a digital computer requires a trade-off between the precision to which these quantities are approximated, and the memory required to store them. The statistical accuracy of the simulation is thus generally limited by the internal memory available to the simulator. Here, using tools from computational mechanics, we show that quantum processors with a fixed finite memory can simulate stochastic processes of real variables to arbitrarily high precision. This demonstrates a provable, unbounded memory advantage that a quantum simulator can exhibit over its best possible classical counterpart. (paper)

  5. Strategic advantages of high-rise construction

    Yaskova Natalya

    2018-01-01

    Full Text Available Traditional methods to assess the competitiveness of different types of real estate in the context of huge changes of new technological way of life don’t provide building solutions that would be correct from a strategic perspective. There are many challenges due to changes in the consumers’ behavior in the housing area. A multiplicity of life models, a variety of opportunities and priorities, traditions and new trends in construction should be assessed in terms of prospective benefits in the environment of the emerging new world order. At the same time, the mane discourse of high-rise construction mainly relates to its design features, technical innovations, and architectural accents. We need to clarify the criteria for economic evaluation of high-rise construction in order to provide decisions with clear and quantifiable contexts. The suggested approach to assessing the strategic advantage of high-rise construction and the prospects for capitalization of high-rise buildings poses new challenges for the economy to identify adequate quantitative assessment methods of the high-rise buildings economic efficiency, taking into account all stages of their life cycle.

  6. Strategic advantages of high-rise construction

    Yaskova, Natalya

    2018-03-01

    Traditional methods to assess the competitiveness of different types of real estate in the context of huge changes of new technological way of life don't provide building solutions that would be correct from a strategic perspective. There are many challenges due to changes in the consumers' behavior in the housing area. A multiplicity of life models, a variety of opportunities and priorities, traditions and new trends in construction should be assessed in terms of prospective benefits in the environment of the emerging new world order. At the same time, the mane discourse of high-rise construction mainly relates to its design features, technical innovations, and architectural accents. We need to clarify the criteria for economic evaluation of high-rise construction in order to provide decisions with clear and quantifiable contexts. The suggested approach to assessing the strategic advantage of high-rise construction and the prospects for capitalization of high-rise buildings poses new challenges for the economy to identify adequate quantitative assessment methods of the high-rise buildings economic efficiency, taking into account all stages of their life cycle.

  7. The Survival Advantage: Underlying Mechanisms and Extant Limitations

    Stephanie A. Kazanas

    2015-04-01

    Full Text Available Recently, researchers have begun to investigate the function of memory in our evolutionary history. According to Nairne and colleagues (e.g., Nairne, Pandeirada, and Thompson, 2008; Nairne, Thompson, and Pandeirada, 2007, the best mnemonic strategy for learning lists of unrelated words may be one that addresses the same problems that our Pleistocene ancestors faced: fitness-relevant problems including securing food and water, as well as protecting themselves from predators. Survival processing has been shown to promote better recall and recognition memory than many well-known mnemonic strategies (e.g., pleasantness ratings, imagery, generation, etc.. However, the survival advantage does not extend to all types of stimuli and tasks. The current review presents research that has replicated Nairne et al.'s (2007 original findings, in addition to the research designs that fail to replicate the survival advantage. In other words, there are specific manipulations in which survival processing does not appear to benefit memory any more than other strategies. Potential mechanisms for the survival advantage are described, with an emphasis on those that are the most plausible. These proximate mechanisms outline the memory processes that may contribute to the advantage, although the ultimate mechanism may be the congruity between the survival scenario and Pleistocene problem-solving.

  8. Elasticity and mechanical advantage in cables and ropes

    O'Shea, M J

    2007-01-01

    The conditions under which one can gain mechanical advantage by pulling with a force F perpendicular to a cable (or rope) that is fixed at both ends are examined. While this is a commonly discussed example in introductory physics classes, its solution in terms of fundamental properties of the cable requires one to model the elasticity of the cable. This solution has several complex and interesting features, e.g. a large increase in the tension in the cable may occur upon application of F if (i) F lies in a certain range and (ii) the initial tension T 1 in the cable (before F is applied) satisfies T 1 < 0.0340 κ. Here, κ is the spring constant of a unit length of the cable. For steel cables and cables composed of other materials such as carbon nanorods where the elasticity is low, significant increases in tension are possible. Examples involving walking a tightrope and attempting to increase the tension in a rope hauling a load are considered. Two programs to solve the equations of this work are available in the electronic version of this journal

  9. Training-dependent cognitive advantage is suppressed at high altitude.

    Li, Peng; Zhang, Gang; You, Hai-Yan; Zheng, Ran; Gao, Yu-Qi

    2012-06-25

    Ascent to high altitude is associated with decreases in cognitive function and work performance as a result of hypoxia. Some workers with special jobs typically undergo intensive mental training because they are expected to be agile, stable and error-free in their job performance. The purpose of this study was to determine the risk to cognitive function acquired from training following hypoxic exposure. The results of WHO neurobehavioral core tests battery (WHO-NCTB) and Raven's standard progressive matrices (RSPM) tests of a group of 54 highly trained military operators were compared with those of 51 non-trained ordinary people and were investigated at sea level and on the fifth day after arrival at high altitudes (3900m). Meanwhile, the plasma levels of brain-derived neurotrophic factor (BDNF), interleukin 1β (IL-1β) and vascular endothelial growth factor (VEGF) were examined. The result showed that at sea level, the trained group exhibited significantly better performance on neurobehavioral and RSPM tests. At high altitude, both groups had decreased accuracy in most cognitive tests and took longer to finish them. More importantly, the highly trained subjects showed more substantial declines than the non-trained subjects in visual reaction accuracy, auditory reaction speed, digit symbol scores, ability to report correct dots in a pursuit aiming test and total RSPM scores. This means that the training-dependent cognitive advantages in these areas were suppressed at high altitudes. The above phenomenon maybe associated with decreased BDNF and elevated inflammatory factor during hypoxia, and other mechanisms could not be excluded. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. The Mechanisms Underlying the ASD Advantage in Visual Search.

    Kaldy, Zsuzsa; Giserman, Ivy; Carter, Alice S; Blaser, Erik

    2016-05-01

    A number of studies have demonstrated that individuals with autism spectrum disorders (ASDs) are faster or more successful than typically developing control participants at various visual-attentional tasks (for reviews, see Dakin and Frith in Neuron 48:497-507, 2005; Simmons et al. in Vis Res 49:2705-2739, 2009). This "ASD advantage" was first identified in the domain of visual search by Plaisted et al. (J Child Psychol Psychiatry 39:777-783, 1998). Here we survey the findings of visual search studies from the past 15 years that contrasted the performance of individuals with and without ASD. Although there are some minor caveats, the overall consensus is that-across development and a broad range of symptom severity-individuals with ASD reliably outperform controls on visual search. The etiology of the ASD advantage has not been formally specified, but has been commonly attributed to 'enhanced perceptual discrimination', a superior ability to visually discriminate between targets and distractors in such tasks (e.g. O'Riordan in Cognition 77:81-96, 2000). As well, there is considerable evidence for impairments of the attentional network in ASD (for a review, see Keehn et al. in J Child Psychol Psychiatry 37:164-183, 2013). We discuss some recent results from our laboratory that support an attentional, rather than perceptual explanation for the ASD advantage in visual search. We speculate that this new conceptualization may offer a better understanding of some of the behavioral symptoms associated with ASD, such as over-focusing and restricted interests.

  11. Size Matters: Problems and Advantages Associated with Highly Miniaturized Sensors

    Dahlin, Andreas B.

    2012-01-01

    There is no doubt that the recent advances in nanotechnology have made it possible to realize a great variety of new sensors with signal transduction mechanisms utilizing physical phenomena at the nanoscale. Some examples are conductivity measurements in nanowires, deflection of cantilevers and spectroscopy of plasmonic nanoparticles. The fact that these techniques are based on the special properties of nanostructural entities provides for extreme sensor miniaturization since a single structu...

  12. Manufacturing Advantage: Why High-Performance Work Systems Pay Off.

    Appelbaum, Eileen; Bailey, Thomas; Berg, Peter; Kalleberg, Arne L.

    A study examined the relationship between high-performance workplace practices and the performance of plants in the following manufacturing industries: steel, apparel, and medical electronic instruments and imaging. The multilevel research methodology combined the following data collection activities: (1) site visits; (2) collection of plant…

  13. Is Extremely High Life Satisfaction during Adolescence Advantageous?

    Suldo, Shannon M.; Huebner, E. Scott

    2006-01-01

    This study examined whether extremely high life satisfaction was associated with adaptive functioning or maladaptive functioning. Six hundred ninety-eight secondary level students completed the Students' Life Satisfaction Scale [Huebner, 1991a, School Psychology International, 12, pp. 231-240], Youth Self-Report of the Child Behavior Checklist…

  14. Knowledge Management and Competitive Advantage: study in the metal-mechanic sector

    Andressa Centenaro

    2016-04-01

    Full Text Available The study aims to analyze the factors related to organizational culture that assist in knowledge management processes, helping to generate competitive advantage in the companies of metal-mechanic sector. Therefore, a quantitative survey data collection strategy was performed by applying a structured questionnaire in a sample of 63 employees from 13 companies in the metal-mechanic sector. The results were analyzed using multiple regression and indicate that the studied segment, learning and trust are positive and significant predictors of knowledge management. Thus, it can be inferred that the companies that stimulate its employees to learn and invest in maintaining confidence among members of the organization may achieve better performance in knowledge management. Finally, the results also expose that the knowledge management directly influences the performance and organizational effectiveness, demonstrating that the use and sharing of tacit and explicit knowledge are generating competitive advantage to competitors.

  15. The advantage of high relaxivity contrast agents in brain perfusion

    Cotton, F.; Hermier, M.

    2006-01-01

    Accurate MRI characterization of brain lesions is critical for planning therapeutic strategy, assessing prognosis and monitoring response to therapy. Conventional MRI with gadolinium-based contrast agents is useful for the evaluation of brain lesions, but this approach primarily depicts areas of disruption of the blood-brain barrier (BBB) rather than tissue perfusion. Advanced MR imaging techniques such as dynamic contrast agent-enhanced perfusion MRI provide physiological information that complements the anatomic data available from conventional MRI. We evaluated brain perfusion imaging with gadobenate dimeglumine (Gd-BOPTA, MultiHance; Bracco Imaging, Milan, Italy). The contrast-enhanced perfusion technique was performed on a Philips Intera 1.5-T MR system. The technique used to obtain perfusion images was dynamic susceptibility contrast-enhanced MRI, which is highly sensitive to T2* changes. Combined with PRESTO perfusion imaging, SENSE is applied to double the temporal resolution, thereby improving the signal intensity curve fit and, accordingly, the accuracy of the derived parametric images. MultiHance is the first gadolinium MR contrast agent with significantly higher T1 and T2 relaxivities than conventional MR contrast agents. The higher T1 relaxivity, and therefore better contrast-enhanced T1-weighted imaging, leads to significantly improved detection of BBB breakdown and hence improved brain tumor conspicuity and delineation. The higher T2 relaxivity allows high-quality T2*-weighted perfusion MRI and the derivation of good quality relative cerebral blood volume (rCBV) maps. We determined the value of MultiHance for enhanced T2*-weighted perfusion imaging of histologically proven (by surgery or stereotaxic biopsy) intraaxial brain tumors (n=80), multiple sclerosis lesions (n=10), abscesses (n=4), neurolupus (n=15) and stroke (n=16). All the procedures carried out were safe and no adverse events occurred. The acquired perfusion images were of good quality in

  16. Advantages of High Tolerance Measurements in Fusion Environments Applying Photogrammetry

    Dodson, T.; Ellis, R.; Priniski, C.; Raftopoulos, S.; Stevens, D.; Viola, M.

    2009-01-01

    Photogrammetry, a state-of-the-art technique of metrology employing digital photographs as the vehicle for measurement, has been investigated in the fusion environment. Benefits of this high tolerance methodology include relatively easy deployment for multiple point measurements and deformation/distortion studies. Depending on the equipment used, photogrammetric systems can reach tolerances of 25 microns (0.001 in) to 100 microns (0.004 in) on a 3-meter object. During the fabrication and assembly of the National Compact Stellarator Experiment (NCSX) the primary measurement systems deployed were CAD coordinate-based computer metrology equipment and supporting algorithms such as both interferometer-aided (IFM) and absolute distance measurement based (ADM) laser trackers, as well as portable Coordinate Measurement Machine (CMM) arms. Photogrammetry was employed at NCSX as a quick and easy tool to monitor coil distortions incurred during welding operations of the machine assembly process and as a way to reduce assembly downtime for metrology processes

  17. THE HIGH LEVEL ACCESSION DIALOGUE FOR MACEDONIA: ADVANTAGES AND DISADVANTAGES

    Mladen Karadjoski

    2015-04-01

    Full Text Available One of the strategic goals for the Republic of Macedonia is membership in the European Union. At the end of 2011, the Commission launched a so-called High Level Accession Dialogue for Macedonia, with a possibility to start the negotiations after the fulfillment of the Dialogue goals and benchmarks. For these reasons, the main goal of this paper will be to give an answer of the dilemma whether the Accession Dialogue for Macedonia is an accelerator of the entrance in the European Union, or is just a sophisticated tool for delay of the start of the negotiations for final accession. The expected results will correspond with the future EU plans for Macedonia, but also for the other Western Balkan countries, i.e. we will try to examine whether these countries have a realistic perspective for entrance in the European Union, or they are just a “declarative décor” for the vocabulary of the Brussels diplomats and member countries representatives. That will help to determine i.e. to try to predict the next steps of these countries, connected with the European integration, regardless of the actual constellation in the European Union concerning the Enlargement policy. The descriptive method, content analyses method, comparative method, but also the inductive and deductive methods will be used in this paper.

  18. The Mechanism of Influence of the Marketing of Innovations on the Competitive Advantages of Enterprise

    Kuznetsova Tatyana V.

    2017-05-01

    Full Text Available The article is aimed at consideration of theoretical approaches and developing practical recommendations on the need to introduce a mechanism for marketing innovations in order to enhance the competitive advantages of enterprise. The conception of marketing innovations is defined as a business philosophy that involves identifying the market opportunities for innovative development of enterprise. Importance of increasing the competitiveness of an enterprise through introducing the marketing of innovations has been proven. The basic principles, functions, and instrumentarium of formation of a mechanism for marketing innovations were considered. A mechanism for implementing the marketing innovations has been proposed that will provide enterprise to retain a sustainable competitive position in the long term. Prospect for further research in this direction will be defining a system of indicators to evaluate the efficiency of impact of marketing activities on the innovation activity of enterprise.

  19. High pressure mechanical seal

    Babel, Henry W. (Inventor); Anderson, Raymond H. (Inventor)

    1996-01-01

    A relatively impervious mechanical seal is formed between the outer surface of a tube and the inside surface of a mechanical fitting of a high pressure fluid or hydraulic system by applying a very thin soft metal layer onto the outer surface of the hard metal tube and/or inner surface of the hard metal fitting. The thickness of such thin metal layer is independent of the size of the tube and/or fittings. Many metals and alloys of those metals exhibit the requisite softness, including silver, gold, tin, platinum, indium, rhodium and cadmium. Suitably, the coating is about 0.0025 millimeters (0.10 mils) in thickness. After compression, the tube and fitting combination exhibits very low leak rates on the order or 10.sup.-8 cubic centimeters per second or less as measured using the Helium leak test.

  20. Mechanical and structural modules in a nuclear power plant advantages of the innovative approach

    Orlandi, S.; De Angelis, F.; Marconi, M.

    2010-01-01

    The modular layout design of a Nuclear Power Plant like the Westinghouse AP600/AP1000 has been developed basically to gain advantages in erection time schedule as well as in minimizing commissioning and start up test to be performed in the field. It is the first time for a Nuclear Power Plant to have a layout configuration fully designed as structured integrated mechanical Modules; this approach has been studied and implemented also to consider already in design phase decommissioning requirements which are mandatory to be able to perform dismantling at the end of the Plant Operation Life. Nevertheless it is the first time the possibility has been investigated to erect the civil structures as structural prefabricated modules: it means to have developed special composite structures which cannot be considered traditional reinforced concrete structures as well as structural beams frames. An approach like the above promotes impressive advantages in terms of extensive prefabrication in the workshops both for mechanical and structural modules, arranging in the workshops also factory acceptance tests as well as specific pre-acceptance commissioning activities. It means also that specific requirements have to be implemented in order to promote the implementation of this technology. Construction and adjustments flexibility in the field during NPP erection is heavily decreased due to modular prefabricated assemblies as well as it is mandatory to complete all the lay out plant design before entering the prefabrication phase in the workshops. Also structural design codes have to be qualified or properly readjusted to manage structural problems in composite structural frames which are innovative for organization, structural behaviour and which have different working ways starting from prefabrication, transportation, lifting up to the installation in the field and concrete pouring. (authors)

  1. High-Cost Patients Had Substantial Rates Of Leaving Medicare Advantage And Joining Traditional Medicare.

    Rahman, Momotazur; Keohane, Laura; Trivedi, Amal N; Mor, Vincent

    2015-10-01

    Medicare Advantage payment regulations include risk-adjusted capitated reimbursement, which was implemented to discourage favorable risk selection and encourage the retention of members who incur high costs. However, the extent to which risk-adjusted capitation has succeeded is not clear, especially for members using high-cost services not previously considered in assessments of risk selection. We examined the rates at which participants who used three high-cost services switched between Medicare Advantage and traditional Medicare. We found that the switching rate from 2010 to 2011 away from Medicare Advantage and to traditional Medicare exceeded the switching rate in the opposite direction for participants who used long-term nursing home care (17 percent versus 3 percent), short-term nursing home care (9 percent versus 4 percent), and home health care (8 percent versus 3 percent). These results were magnified among people who were enrolled in both Medicare and Medicaid. Our findings raise questions about the role of Medicare Advantage plans in serving high-cost patients with complex care needs, who account for a disproportionately high amount of total health care spending. Project HOPE—The People-to-People Health Foundation, Inc.

  2. Advantage of highly immunoreactive monoclonal antibodies in radioimmunoscintigraphy for tumor detection, (1)

    Yokoyama, Kunihiko

    1988-01-01

    Immunoreactivity (IR) is the fraction of a monoclonal antibody (MoAb) preparation capable of binding to an excess of a specific antigen. One of the most important requirements for successful radioimmunoscintigraphy is to use a highly immunoreactive MoAb. To assess the effect of an antibody IR on biodistribution, a fast and simple purification method has been developed using a high performance liquid chromatography (HPLC) system equipped with a hydroxylapatite (HA) column. The column was eluted at ambient temperature with 0.12 M sodium phosphate buffer (pH 6.8). With this system, the F ab fragments from the MoAb 96.5 against the human melanoma associated p97 antigen were separated into two well-resolved peaks at retention times of 6 and 16 min. FEM-XII cells (human skin melanoma cell line) were used in a cell binding assay (CBA) to determine the maximal percent IR and the affinity constant of each HA-HPLC peak. The second peak from an 125 I-F ab 96.5 showed approximately two times greater maximal binding than did the first peak, whereas the affinity constant for the two was the same. This indicated that the F ab 96.5 preparations used in this study were a mixture of more active and less active components. Moreover, prior to the HA-HPLC experiments, these preparations were analyzed with a gel filtration HPLC showing a single molecular weight peak. This suggested that the HA-HPLC separation was not based on molecular weight differences although the separation mechanism of HA has not yet been fully understood. Thereby, it is concluded that the HA-HPLC is a powerful tool to purify MoAbs into the higher immunoreactive fraction which has a potential advantage in tumor targeting. (author)

  3. Advantages of high-dose rate (HDR) brachytherapy in treatment of prostate cancer

    Molokov, A. A.; Vanina, E. A.; Tseluyko, S. S.

    2017-09-01

    One of the modern methods of preserving organs radiation treatment is brachytherapy. This article analyzes the results of prostate brachytherapy. These studies of the advantages of high dose brachytherapy lead to the conclusion that this method of radiation treatment for prostate cancer has a favorable advantage in comparison with remote sensing methods, and is competitive, preserving organs in comparison to surgical methods of treatment. The use of the method of polyfocal transperineal biopsy during the brachytherapy session provides information on the volumetric spread of prostate cancer and adjust the dosimetry plan taking into account the obtained data.

  4. Mechanical lifter for recovering highly viscous oil and bitumens

    Rakhmanov, R N; Akhunov, A M; Asfandiyarov, Kh A; Maksutov, R A

    1982-01-01

    A mechanical lifter is described for recovering highly viscous oil and bitumens. The lifter differs from the known and has significant advantages over them. The lifter was made and tested on a stand well.

  5. High temperature materials and mechanisms

    2014-01-01

    The use of high-temperature materials in current and future applications, including silicone materials for handling hot foods and metal alloys for developing high-speed aircraft and spacecraft systems, has generated a growing interest in high-temperature technologies. High Temperature Materials and Mechanisms explores a broad range of issues related to high-temperature materials and mechanisms that operate in harsh conditions. While some applications involve the use of materials at high temperatures, others require materials processed at high temperatures for use at room temperature. High-temperature materials must also be resistant to related causes of damage, such as oxidation and corrosion, which are accelerated with increased temperatures. This book examines high-temperature materials and mechanisms from many angles. It covers the topics of processes, materials characterization methods, and the nondestructive evaluation and health monitoring of high-temperature materials and structures. It describes the ...

  6. THE MECHANISM OF ORGANIZATIONAL CULTURE TRANSFORMATION IN INNOVATION COMPETITIVE ADVANTAGE FOR INTERNATIONAL BUSINESS STRUCTURES

    Lidia S. Leontieva

    2015-01-01

    Full Text Available Throughout article authors give algorithm of organizational culture diagnostic testing of the Hyundai Glovis Russia company, features and difficulties of her cross-cultural environment. Within research the corporate culture and history of the Hyundai Glovis Russia company is analysed. Besides, systems of norms, values and behavior models of the Korean and Russian personnel, and also set of forms of interaction between them are compared. The structural model of transformation of cultural distinctions in competitive advantages of the international enterprise structures is developed.

  7. CORPORATE ENTREPRENEURSHIP AS A MECHANISM TO TURN INNOVATION INTO COMPETITIVE ADVANTAGE

    GRAȚIELA MIHAELA FERARU

    2017-11-01

    Full Text Available Corporate Entrepreneurship creates the environment where preparation (engaged employees that own knowhow and resources meets opportunity (generated by the current business environment where corporations perform their activities. The current paper aims to identify to what extent corporate entrepreneurship enables the pursuit and exploitation of business opportunities in order to maintain competitive position by focusing on the main implications and risks. During current times, the competitive landscape challenges corporations to focus on new initiatives in order to gain and maintain competitive advantage. Intense competition, as much as rapid technological progress, leads to industry-wide restructuring, challenging big companies to adapt. Corporations that seek quick wins realized that neither cost cutting nor mergers are enough to achieve short term goals or even to play the game. Not adapting generates the switch to an unintentional strategic decision to be out of business. Volatility of current environment has highlighted the need for companies to become entrepreneurial in order to capture (identify and value the business opportunities. The need for innovation is not only a priority for start-ups; it is also a strategic goal for large companies. Creating new businesses within corporations is the challenge of the day in order to maintain a competitive position and to grow.

  8. THE MECHANISM OF ORGANIZATIONAL CULTURE TRANSFORMATION ININNOVATION COMPETITIVE ADVANTAGE FOR INTERNATIONAL BUSINESSSTRUCTURES

    Lidia S. Leontieva

    2015-01-01

    Full Text Available The article presents mechanisms of organizational culture formation and development in the conditions of cross-cultural interaction on the example of the international enterprise structures - Hyundai Motor Corporation group of companies and its affiliated structures are considered: «Hyundai Glovis» and Russian company «Hyundai Glovis Russia». The Russian and Korean cultural aspects of business and daily communication feature of mentality of two cultures, the priority directions of development of organizational culture based on cross-cultural interaction are analyzed for this purpose.

  9. Enhanced shoot investment makes invasive plants exhibit growth advantages in high nitrogen conditions.

    Liu, X A; Peng, Y; Li, J J; Peng, P H

    2018-03-12

    Resource amendments commonly promote plant invasions, raising concerns over the potential consequences of nitrogen (N) deposition; however, it is unclear whether invaders will benefit from N deposition more than natives. Growth is among the most fundamental inherent traits of plants and thus good invaders may have superior growth advantages in response to resource amendments. We compared the growth and allocation between invasive and native plants in different N regimes including controls (ambient N concentrations). We found that invasive plants always grew much larger than native plants in varying N conditions, regardless of growth- or phylogeny-based analyses, and that the former allocated more biomass to shoots than the latter. Although N addition enhanced the growth of invasive plants, this enhancement did not increase with increasing N addition. Across invasive and native species, changes in shoot biomass allocation were positively correlated with changes in whole-plant biomass; and the slope of this relationship was greater in invasive plants than native plants. These findings suggest that enhanced shoot investment makes invasive plants retain a growth advantage in high N conditions relative to natives, and also highlight that future N deposition may increase the risks of plant invasions.

  10. Invaders do not require high resource levels to maintain physiological advantages in a temperate deciduous forest.

    Heberling, J Mason; Fridley, Jason D

    2016-04-01

    Non-native, invasive plants are commonly typified by trait strategies associated with high resource demands and plant invasions are often thought to be dependent upon site resource availability or disturbance. However, the invasion of shade-tolerant woody species into deciduous forests of the Eastern United States seems to contradict such generalization, as growth in this ecosystem is strongly constrained by light and, secondarily, nutrient stress. In a factorial manipulation of light and soil nitrogen availability, we established an experimental resource gradient in a secondary deciduous forest to test whether three common, woody, invasive species displayed increased metabolic performance and biomass production compared to six co-occurring woody native species, and whether these predicted differences depend upon resource supply. Using hierarchical Bayesian models of photosynthesis that included leaf trait effects, we found that invasive species exhibited functional strategies associated with higher rates of carbon gain. Further, invader metabolic and growth-related attributes were more responsive to increasing light availability than those of natives, but did not fall below average native responses even in low light. Surprisingly, neither group showed direct trait or growth responses to soil N additions. However, invasive species showed increased photosynthetic nitrogen use efficiencies with decreasing N availability, while that of natives remained constant. Although invader advantage over natives was amplified in higher resource conditions in this forest, our results indicate that some invasive species can maintain physiological advantages over co-occurring natives regardless of resource conditions.

  11. Multiwavelength Thermometry at High Temperature: Why It is Advantageous to Work in the Ultraviolet

    Girard, F.; Battuello, M.; Florio, M.

    2014-07-01

    In principle, multiwavelength radiation thermometry allows one to correctly measure the temperature of surfaces of unknown and varying surface emissivity. Unfortunately, none of the practical realizations proposed in the past proved to be sufficiently reliable because of a strong influence of the errors arising from incorrect modeling of the emissivity and of the limited number of operating wavelengths. The use of array detectors allows a high degree of flexibility both in terms of number and spectral position of the working wavelength bands. In the case of applications at high temperatures, i.e., near 2000 C or above, an analysis of the theoretical measuring principles of multiwavelength thermometry, suggests the opportunity of investigating the possible advantages in extending the operating wavelengths toward the ultraviolet region. To this purpose, a simulation program was developed which allows investigation of the effect of different influencing parameters. This paper presents a brief theoretical introduction and practical analysis of the method. The best choices are derived in terms of the different influencing parameters and data relative to the simulation of both real materials and fictitious emissivity curves and have been studied and analyzed with different emissivity models to check the robustness of the method.

  12. Concretes with high mechanical resistance

    Mauny, Pierre.

    1973-01-01

    Description is given of a method for manufacturing concretes with high mechanical resistance in compression, obtained by mixing gravels highly resistant to compression, sand and cement in an aqueous medium. Use is made of sands of porous ceramics, such as terra-cotta, of a grain size from 0,1 to 5mm, the pore diameter of which is from 0.5 to 15 microns, chosen so as to be slighty bigger than the crystals of the cement used. This can be applied to the pre-stressed structures used in the nuclear field [fr

  13. Assessment of potential advantages of high Tc-superconductors for technical application of superconductivity

    Schauer, F.; Juengst, K.P.; Komarek, P.; Maurer, W.

    1987-09-01

    A first assessment of the technical and economical consequences of liquid nitrogen cooling of new superconductors is given. For the investigation the applications of superconductivity are classified in two categories: First, systems where superconductors are practically indispensable for achieving the system's objectives; second, superconductor applications in competition with highly developed conventional technologies. Further development of those superconducting systems in the first category for which the cost of cryogenic equipment is a smaller fraction of the total system cost (e.g. fusion reactor or MHD generator) will hardly be affected. However, for systems like particle accelerators, research magnets, and NMR spectroscopy and imaging systems, the cryogenic equipment expenditures are significant and LN 2 cooling leads here to a reduction of investment and operating costs, to simplified handling and maintenance, to better reliability and availability, and will thereby improve the acceptance and further spread of these systems. In the second category each application of superconductivity has to be compared with its conventional counterpart, separately. Here, electonic components, power switches, resistive current limiters, and especially the power transmission cables are those applications which look most promising. For magnet applications the main advantageous arguments are less the cost saving aspect but more the higher reliability, simplicity, N 2 -availability, and ease of handling. (orig.) [de

  14. Advantage of the Highly Restricted Odorant Receptor Expression Pattern in Chemosensory Neurons of Drosophila.

    Tharadra, Sana Khalid; Medina, Adriana; Ray, Anandasankar

    2013-01-01

    A fundamental molecular feature of olfactory systems is that individual neurons express only one receptor from a large odorant receptor gene family. While numerous theories have been proposed, the functional significance and evolutionary advantage of generating a sophisticated one-receptor-per neuron expression pattern is not well understood. Using the genetically tractable Drosophila melanogaster as a model, we demonstrate that the breakdown of this highly restricted expression pattern of an odorant receptor in neurons leads to a deficit in the ability to exploit new food sources. We show that animals with ectopic co-expression of odorant receptors also have a competitive disadvantage in a complex environment with limiting food sources. At the level of the olfactory system, we find changes in both the behavioral and electrophysiological responses to odorants that are detected by endogenous receptors when an olfactory receptor is broadly misexpressed in chemosensory neurons. Taken together these results indicate that restrictive expression patterns and segregation of odorant receptors to individual neuron classes are important for sensitive odor-detection and appropriate olfactory behaviors.

  15. Surgical Treatment of Valvular Heart Disease: Overview of Mechanical and Tissue Prostheses, Advantages, Disadvantages, and Implications for Clinical Use.

    Fiedler, Amy G; Tolis, George

    2018-02-05

    Valvular heart disease (VHD) affects a large number of patients annually. From a surgical standpoint, there are two primary options for valve replacement: mechanical or bioprosthetic. While there are clear advantages and disadvantages to either option, and recent literature does challenge some of the prior dictums of valve choice, a handful of absolutes remain true. Mechanical valves provide superior durability and freedom from re-operation when compared to their bioprosthetic counterparts, at the expense of bleeding or thrombotic complications associated with the need for lifelong oral anticoagulation. Unless a clear contraindication to oral anticoagulation exists, we recommend implanting mechanical valves for patients less than 60 years old and those who are older than 65 but maintained on anticoagulation for reasons other than their valvular disease. Bioprosthetic valves should be placed in patients who are greater than 65 years old or those patients who have a postoperative life expectancy of less than 10 years. Valve choice in patients between the ages of 60 to 70 is not dictated by guidelines and is less clear, with patient preference playing a larger role than their age range.

  16. Institutional advantage

    Martin, Xavier

    Is there such a thing as institutional advantage—and what does it mean for the study of corporate competitive advantage? In this article, I develop the concept of institutional competitive advantage, as distinct from plain competitive advantage and from comparative institutional advantage. I first

  17. New high strength technologically ecological and expedient economically advantageous alloys on Fe-C base

    Kolev, B.V.

    2003-01-01

    The paper presents framework a part of by now obtained results of the authors studies in the period 1967(68) - 2002 about possibilities for obtaining new high-strength and wear resistant cast alloys on, Fe-C base (complex alloyed steels and cast irons of different systems with different structure, reflected in over 125 articles, 15 inventions (patents) and other scientific studies. The paper includes summarized results and discussion. Key words: new austenite steels and cast irons, mechanical characteristics, wear resistance. (Original)

  18. MR angiography of the carotid arteries and intracranial circulation: advantage of a high relaxivity contrast agent

    Anzalone, N.; Scotti, R.; Iadanza, A.

    2006-01-01

    Several studies have shown the usefulness of contrast-enhanced MR angiography (CE-MRA) for imaging the supraortic vessels, and, as a consequence, it has rapidly become a routine imaging modality. The main advantage over unenhanced techniques is the possibility to acquire larger volumes, allowing demonstration of the carotid artery from its origin to the intracranial portion. Most published studies on CE-MRA of the carotid arteries have been performed with standard Gd-based chelates whose T1 relaxivity values are similar. Recently new gadolinium chelates such as gadobenate dimeglumine (Gd-BOP-TA, MultiHance; Bracco Imaging, Milan, Italy) have been developed which have markedly higher intravascular T1 relaxivity values. When administered at an equivalent dose to that of a standard agent, these newer contrast agents produce significantly greater intravascular signal enhancement. The availability of an appropriate high-relaxivity contrast agent might also help to overcome some of the intrinsic technical problems (e. g. those related to flow) that affect time-of-flight (TOF) and phase contrast (PC) MR angiography of the intracranial vasculature. To avoid the problem of superimposition of veins, ultrafast gradient echo MRA techniques with very short TR and TE have been developed. Although the precise sequence parameters vary between manufacturers, they are basically similar. The choice between performing a time-resolved or high spatial resolution CE-MRA examination depends upon the precise clinical application. The most common applications include the study of cerebral aneurysms, arteriovenous malformations, dural arteriovenous fistulas and dural venous diseases

  19. Post and core build-ups in crown and bridge abutments: Bio-mechanical advantages and disadvantages.

    Mamoun, John

    2017-06-01

    Dentists often place post and core buildups on endodontically treated abutments for crown and bridge restorations. This article analyzes the bio-mechanical purposes, advantages and disadvantages of placing a core or a post and core in an endodontically treated tooth and reviews literature on post and core biomechanics. The author assesses the scientific rationale of the claim that the main purpose of a post is to retain a core, or the claim that posts weaken teeth. More likely, the main function of a post is to help prevent the abutment, on which a crown is cemented, from fracturing such that the abutment separates from the tooth root, at a fracture plane that is located approximately and theoretically at the level of the crown (or ferrule) margin. A post essentially improves the ferrule effect that is provided by the partial fixed denture prosthesis. This paper also explores the difference between bio-mechanical failures of crowns caused by lack of retention or excess taper, versus failures due to a sub-optimal ferrule effect in crown and bridge prostheses.

  20. Advantages of the experimental animal hollow organ mechanical testing system for the rat colon rupture pressure test.

    Ji, Chengdong; Guo, Xuan; Li, Zhen; Qian, Shuwen; Zheng, Feng; Qin, Haiqing

    2013-01-01

    Many studies have been conducted on colorectal anastomotic leakage to reduce the incidence of anastomotic leakage. However, how to precisely determine if the bowel can withstand the pressure of a colorectal anastomosis experiment, which is called anastomotic bursting pressure, has not been determined. A task force developed the experimental animal hollow organ mechanical testing system to provide precise measurement of the maximum pressure that an anastomotic colon can withstand, and to compare it with the commonly used method such as the mercury and air bag pressure manometer in a rat colon rupture pressure test. Forty-five male Sprague-Dawley rats were randomly divided into the manual ball manometry (H) group, the tracing machine manometry pressure gauge head (MP) group, and the experimental animal hollow organ mechanical testing system (ME) group. The rats in each group were subjected to a cut colon rupture pressure test after injecting anesthesia in the tail vein. Colonic end-to-end anastomosis was performed, and the rats were rested for 1 week before anastomotic bursting pressure was determined by one of the three methods. No differences were observed between the normal colon rupture pressure and colonic anastomotic bursting pressure, which were determined using the three manometry methods. However, several advantages, such as reduction in errors, were identified in the ME group. Different types of manometry methods can be applied to the normal rat colon, but the colonic anastomotic bursting pressure test using the experimental animal hollow organ mechanical testing system is superior to traditional methods. Copyright © 2013 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

  1. Generic Advantages

    First page Back Continue Last page Overview Graphics. Generic Advantages. Scalability an incremental coverage. Standardization. Business Plan Flexibility. Lifecycle Flexibility. Reliability. Service Interoperability. Changed Industry dynamics.

  2. Home advantage in high-level volleyball varies according to set number.

    Marcelino, Rui; Mesquita, Isabel; Palao Andrés, José Manuel; Sampaio, Jaime

    2009-01-01

    The aim of the present study was to identify the probability of winning each Volleyball set according to game location (home, away). Archival data was obtained from 275 sets in the 2005 Men's Senior World League and 65,949 actions were analysed. Set result (win, loss), game location (home, away), set number (first, second, third, fourth and fifth) and performance indicators (serve, reception, set, attack, dig and block) were the variables considered in this study. In a first moment, performance indicators were used in a logistic model of set result, by binary logistic regression analysis. After finding the adjusted logistic model, the log-odds of winning the set were analysed according to game location and set number. The results showed that winning a set is significantly related to performance indicators (Chisquare(18)=660.97, padvantage at the beginning of the game (first set) and in the two last sets of the game (fourth and fifth sets), probably due to facilities familiarity and crowd effects. Different game actions explain these advantages and showed that to win the first set is more important to take risk, through a better performance in the attack and block, and to win the final set is important to manage the risk through a better performance on the reception. These results may suggest intra-game variation in home advantage and can be most useful to better prepare and direct the competition. Key pointsHome teams always have more probability of winning the game than away teams.Home teams have higher performance in reception, set and attack in the total of the sets.The advantage of home teams is more pronounced at the beginning of the game (first set) and in two last sets of the game (fourth and fifth sets) suggesting intra-game variation in home advantage.Analysis by sets showed that home teams have a better performance in the attack and block in the first set and in the reception in the third and fifth sets.

  3. Absolute advantage

    J.G.M. van Marrewijk (Charles)

    2008-01-01

    textabstractA country is said to have an absolute advantage over another country in the production of a good or service if it can produce that good or service using fewer real resources. Equivalently, using the same inputs, the country can produce more output. The concept of absolute advantage can

  4. The advantages and disadvantages of using high technology in hand rehabilitation.

    Levanon, Yafi

    2013-01-01

    A brief review of the history of occupational therapy shows that the relationship between health and activity was of great concern to the founders of the Occupational Therapy (OT) field, and continues to be of concern to today's occupational therapists. Today, computers and Virtual Reality (VR) take the place of clay and the weaving loom. The goal of this article is to describe both known and innovative computerized equipment being used in interventions for hand rehabilitation and evaluations, as well as answer the question: 'what are the advantages and disadvantages of using technology in hand rehabilitation?' Our conclusion, based on clinical experience and supported by the literature, appears to emphasize that advanced technology can enrich treatment and help patients who are unable to visit the clinic regularly, to get appropriate treatment. However, advanced technology has not been found to be superior to traditional treatment and cannot replace the occupational therapist. Copyright © 2013 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  5. Non-Foster Circuits for High Performance Antennas: Advantages and Practical Limitations

    Jacob, Minu Mariam

    The demand for miniaturized, broadband communication systems has created a need for electrically small, broadband antennas. However, all passive electrically small antennas have a fundamental gain-bandwidth limitation related to their electrical size, as first described by Wheeler and Chu. This limitation can be overcome using active non-Foster circuits (negative inductors and/or negative capacitors), which can deliver a broadband input match with active matching techniques, or can help reduce phase dispersion using negative delay effects. This thesis will illustrate the advantages of non-Foster circuits in obtaining broadband small antennas, in addition to examining their practical limitations due to noise in receive applications, and nonlinearity in transmit applications.

  6. The Advantages of High/Scope: Helping Children Lead Successful Lives.

    Schweinhart, Lawrence J.; Weikart, David P.

    1999-01-01

    The High/Scope educational approach emphasizes child-initiated learning activities for preschool/elementary school children. A research study shows that compared to children receiving direct instruction, High/Scope kids later showed more prosocial and less antisocial behaviors. Another study showed that poor High/Scope students had better…

  7. Advantages of computer cameras over video cameras/frame grabbers for high-speed vision applications

    Olson, Gaylord G.; Walker, Jo N.

    1997-09-01

    Cameras designed to work specifically with computers can have certain advantages in comparison to the use of cameras loosely defined as 'video' cameras. In recent years the camera type distinctions have become somewhat blurred, with a great presence of 'digital cameras' aimed more at the home markets. This latter category is not considered here. The term 'computer camera' herein is intended to mean one which has low level computer (and software) control of the CCD clocking. These can often be used to satisfy some of the more demanding machine vision tasks, and in some cases with a higher rate of measurements than video cameras. Several of these specific applications are described here, including some which use recently designed CCDs which offer good combinations of parameters such as noise, speed, and resolution. Among the considerations for the choice of camera type in any given application would be such effects as 'pixel jitter,' and 'anti-aliasing.' Some of these effects may only be relevant if there is a mismatch between the number of pixels per line in the camera CCD and the number of analog to digital (A/D) sampling points along a video scan line. For the computer camera case these numbers are guaranteed to match, which alleviates some measurement inaccuracies and leads to higher effective resolution.

  8. Advantages of Real-Time Spectrum Analyzers in High-Energy Physics Applications

    Parker, Louis

    2004-01-01

    Typically, particles are injected into the ring at low energy levels and then 'ramped up' to higher levels. During ramping, it is important that the horizontal and vertical tune frequencies do not shift, lest they hit upon a resonant combination that causes beam instability or sudden total loss of ring beam current (beam blow up). Beam instabilities can be caused by a number of factors. Non-linearities and/or different response times of independent controls such as beam position monitor (BPM) cables and circuits, magnets for guidance and focusing of the beam, Klystrons or Tetrodes (which provide power to RF cavities that transmit energy to the beam), and vacuum pumps and monitors can all cause beam instabilities. Vibrations and lack of proper shielding are other factors. The challenge for operators and researchers is to correctly identify the factors causing beam instabilities and blow up so that costly accelerator time is not interrupted and experimental results are not compromised. The instrument often used to identify problems in particle accelerator applications is the spectrum analyzer. This paper will discuss the advantages of real time spectrum analyzers (RSA) versus swept frequency spectrum analyzers in HEP applications. The main focus will be on monitoring beam position and stability, especially during ramp-up. Also covered will be use of RSA for chromaticity measurements, Phase Locked Loop (PLL) diagnostics, and vibration analysis

  9. Physiological advantages of dwarfing in surviving extinctions in high-CO2 oceans

    Garilli, Vittorio; Rodolfo-Metalpa, Riccardo; Scuderi, Danilo; Brusca, Lorenzo; Parrinello, Daniela; Rastrick, Samuel P. S.; Foggo, Andy; Twitchett, Richard J.; Hall-Spencer, Jason M.; Milazzo, Marco

    2015-07-01

    Excessive CO2 in the present-day ocean-atmosphere system is causing ocean acidification, and is likely to cause a severe biodiversity decline in the future, mirroring effects in many past mass extinctions. Fossil records demonstrate that organisms surviving such events were often smaller than those before, a phenomenon called the Lilliput effect. Here, we show that two gastropod species adapted to acidified seawater at shallow-water CO2 seeps were smaller than those found in normal pH conditions and had higher mass-specific energy consumption but significantly lower whole-animal metabolic energy demand. These physiological changes allowed the animals to maintain calcification and to partially repair shell dissolution. These observations of the long-term chronic effects of increased CO2 levels forewarn of changes we can expect in marine ecosystems as CO2 emissions continue to rise unchecked, and support the hypothesis that ocean acidification contributed to past extinction events. The ability to adapt through dwarfing can confer physiological advantages as the rate of CO2 emissions continues to increase.

  10. A World of Competitors: Assessing the US High-Tech Advantage and the Process of Globalisation

    Douglass, John Aubrey

    2008-01-01

    Research universities throughout the world are part of a larger effort by countries to bolster science and technological innovation and compete economically. The United States remains highly competitive as a source of high-tech innovation because of a number of market positions, many the results of long-term investments in institutions (such as…

  11. Retail offer advantage through brand orientation in Luxury, high fashion stores

    Grujic, Maja

    2007-01-01

    This thesis provides a conceptualisation of brand orientation within the context of fashion retailing, specially the luxury, or, so-called, high fashion retailing. Most of the high fashion sold today is ready to wear collections and diffusion lines, targeted to customers of particular class, age, income, social status, and with particular orientations to fashion. In plethora of offers, retailer need to work on a number of distinctive features that will make its store special, not only because...

  12. Advantages and Limits of 4H-SIC Detectors for High- and Low-Flux Radiations

    Sciuto, A.; Torrisi, L.; Cannavò, A.; Mazzillo, M.; Calcagno, L.

    2017-11-01

    Silicon carbide (SiC) detectors based on Schottky diodes were used to monitor low and high fluxes of photons and ions. An appropriate choice of the epilayer thickness and geometry of the surface Schottky contact allows the tailoring and optimizing the detector efficiency. SiC detectors with a continuous front electrode were employed to monitor alpha particles in a low-flux regime emitted by a radioactive source with high energy (>5.0 MeV) or generated in an ion implanter with sub-MeV energy. An energy resolution value of 0.5% was measured in the high energy range, while, at energy below 1.0 MeV, the resolution becomes 10%; these values are close to those measured with a traditional silicon detector. The same SiC devices were used in a high-flux regime to monitor high-energy ions, x-rays and electrons of the plasma generated by a high-intensity (1016 W/cm2) pulsed laser. Furthermore, SiC devices with an interdigit Schottky front electrode were proposed and studied to overcome the limits of the such SiC detectors in the detection of low-energy (˜1.0 keV) ions and photons of the plasmas generated by a low-intensity (1010 W/cm2) pulsed laser. SiC detectors are expected to be a powerful tool for the monitoring of radioactive sources and ion beams produced by accelerators, for a complete characterization of radiations emitted from laser-generated plasmas at high and low temperatures, and for dosimetry in a radioprotection field.

  13. Taking advantage of the Kyoto mechanisms in the natural gas industry; Benefices des mecanismes de Kyoto pour l'industrie du gaz naturel

    Janssen, J. [Institute for Economy and the environment at the University of St. Gallen, IWOe-HSG (Switzerland)

    2000-07-01

    The Kyoto Protocol has laid the basis of global markets for greenhouse gas emission reductions. By means of the Kyoto Mechanisms Joint Implementation, the Clean Development Mechanism and International Emissions Trading it will be possible to produce abroad and trade internationally the greenhouse gas emission reductions needed to satisfy cost-efficiently the respective demand of industrialized countries. The paper analyses options available in the natural gas sector for realizing Joint Implementation and Clean Development Mechanism projects. Furthermore, it examines strategies that might be economically viable for companies operating in the natural gas sector for taking advantage of the Kyoto Mechanisms. (author)

  14. Comparative Advantage

    Zhang, Jie; Jensen, Camilla

    2007-01-01

    that are typically explained from the supply-side variables, the comparative advantage of the exporting countries. A simple model is proposed and tested. The results render strong support for the relevance of supply-side factors such as natural endowments, technology, and infrastructure in explaining international...

  15. High Speed Rail Learning System (HSRLS – Taking Advantage of Online Technologies in Railway Education

    Pasi T. Lautala, Ph.D., P.E.

    2015-06-01

    Full Text Available The United States has taken initial steps toward developing a high speed rail (HSR network, but the domestic workforce experience and institutional knowledge necessary for the planning, design, construction, and operations of HSR is underdeveloped. This paper describes and provides preliminary assessment of the High Speed Rail Learning System (HSRLS, a demonstration project that seeks to address gaps in HSR knowledge and skills in the US. The HSRLS developers designed an online education system to serve as a clearinghouse for rail-related information and content, connect teachers, trainers, and students at pre-, and postgraduate levels, and to collect demographic and professional information on groups and individuals interested in HSR. The paper explores the technology review, selection process, and content developed. Website visits and demographic information from over 4,000 unique individuals and 600 HSRLS course registrations are analyzed and assessed.

  16. Intracavitary after loading techniques, advantages and disadvantages with high and low dose-rate methods

    Walstam, Rune

    1980-01-01

    Even though suggested as early as 1903, it is only when suitable sealed gamma sources became available, afterloading methods could be developed for interstitial as well as intracavitary work. Manual afterloading technique can be used only for low dose rate irradiation, while remote controlled afterloading technique can be used for both low and high dose-rate irradiation. Afterloading units used at the Karolinska Institute, Stockholm, are described, and experience of their use is narrated briefly. (M.G.B.)

  17. [Renal biopsy in the lateral position in high risk patients: an opportunity to take advantage of].

    Dugo, Mauro; Brisotto, Elisa; Vitturi, Nicola; Pasi, Alessandra; Mastrosimone, Stefania; Farneti, Fabrizio; Mangino, Margherita; Virgilio, Bice; Brunello, Anna; Pastori, Giordano; Mazzoli, Matteo; Laurino, Licia; Cova, Giandavide; Beniamin, Francesco; Maresca, Maria Cristina

    2015-01-01

    Percutaneous ultrasound-guided renal biopsy (RB) is the gold standard for diagnosis of renal diseases. The standard procedure involves biopsy in the prone position (PP) for the native kidneys. In high risk patients, transjugular and laparoscopic RB have been proposed. In patients suffering from obesity or respiratory diseases, the RB of the native kidney in the supine anterolateral position (SALP) represents an alternative to these invasive and expensive methods. We illustrate the technique of execution of RB in the lateral position (LP) on native kidneys. The procedure is safe, effective and has reduced the path travelled by the needle biopsy compared with PP and SALP.

  18. Advantages and disadvantages of high power ultrasound application in the dairy industry

    Mislav Muža

    2009-12-01

    Full Text Available Preservation of food with thermal sterilisation is usually the most common way nowadays. Besides the positive aim of preservation regarding microorganisms’ reduction, elevated temperature in processing simultaneously causes serious changes in nutritive and organoleptical properties of food. Loss of food quality is related to structure and texture deformations, modification of macromolecules and creation of new compounds coming from reactions that are catalised with temperature. One of the new non-thermal processes that can in large scale improve different processes in food industry is ultrasound. In the last five years, new applications of high power ultrasound (HPU include inactivation of enzymes and microorganisms, assistance in membrane processes, improvement of dairy product texture, improvement of functional properties of proteins etc. High power ultrasound application is used in emulsification and milk homogenization, but in these processes the most important thing is to monitor possible negative effect like oxidation of fats, inactivation of valuable enzymes and denaturation of proteins. Controled and optimized application of ultrasound demands application of specific ultrasound frequency and optimal treatment time. Treatments should be performed at lower temperatures to avoid negative side effects on treated materials.

  19. Advantageous GOES IR results for ash mapping at high latitudes: Cleveland eruptions 2001

    Gu, Yingxin; Rose, William I.; Schneider, D.J.; Bluth, G.J.S.; Watson, I.M.

    2005-01-01

    The February 2001 eruption of Cleveland Volcano, Alaska allowed for comparisons of volcanic ash detection using two-band thermal infrared (10-12 ??m) remote sensing from MODIS, AVHRR, and GOES 10. Results show that high latitude GOES volcanic cloud sensing the range of about 50 to 65??N is significantly enhanced. For the Cleveland volcanic clouds the MODIS and AVHRR data have zenith angles 6-65 degrees and the GOES has zenith angles that are around 70 degrees. The enhancements are explained by distortion in the satellite view of the cloud's lateral extent because the satellite zenith angles result in a "side-looking" aspect and longer path lengths through the volcanic cloud. The shape of the cloud with respect to the GOES look angle also influences the results. The MODIS and AVHRR data give consistent retrievals of the ash cloud evolution over time and are good corrections for the GOES data. Copyright 2005 by the American Geophysical Union.

  20. Venom Immunotherapy in High-Risk Patients: The Advantage of the Rush Build-Up Protocol.

    Rosman, Yossi; Confino-Cohen, Ronit; Goldberg, Arnon

    2017-01-01

    Venom immunotherapy (VIT) is considered to be the gold standard treatment for patients with hymenoptera venom allergy. This treatment induces systemic reactions (SR) in a significant number of patients. To evaluate the outcome of VIT in patients with known risk factors for VIT-induced SR and to compare rush VIT (RVIT) and conventional VIT (CVIT). All of the patients who received VIT and had at least one of the following risk factors were included: current cardiovascular disease, uncontrolled asthma, high basal serum tryptase, current treatment with β-blockers or angiotensin-converting enzyme inhibitors, and age >70 or bee venom. Thirty-five (54.7%) patients underwent RVIT and 29 CVIT. The incidence of patients who developed SR during the build-up phase was similar for RVIT and CVIT (25.7 and 27.5%, respectively; p = 1). However, the incidence of SR per injection was significantly higher in CVIT than in RVIT (5.6 and 2.75%, respectively; p = 0.01). Most reactions (79.1%) were mild, limited to the skin. Most of the patients (92.1%) reached the full maintenance dose of 100 μg. This dose was reached by a significantly larger number of patients receiving RVIT compared to CVIT (100 and 82.7%, respectively; p = 0.01). None of the patients experienced exacerbation of their concurrent chronic disease during VIT. VIT can be performed safely and efficiently in patients with risk factors for immunotherapy. In these patients RVIT appears to be safer and more efficient than CVIT. © 2017 S. Karger AG, Basel.

  1. Explore the advantage of High-frequency Water Quality Data in Urban Surface Water: A Case Study in Bristol, UK

    Chen, Y.; Han, D.

    2017-12-01

    Water system is an essential component in a smart city for its sustainability and resilience. The freshness and beauty of the water body would please people as well as benefit the local aquatic ecosystems. Water quality monitoring approach has evolved from the manual lab-based monitoring approach to the manual in-situ monitoring approach, and finally to the latest wireless-sensor-network (WSN) based solutions in recent decades. The development of the in-situ water quality sensors enable humans to collect high-frequency and real-time water quality data. This poster aims to explore the advantages of the high-frequency water quality data over the low-frequency data collected manually. The data is collected by a remote real-time high-frequency water quality monitor system based on the cutting edge smart city infrastructure in Bristol - `Bristol Is Open'. The water quality of Bristol Floating Harbour is monitored which is the focal area of Bristol with new buildings and features redeveloped in the past decades. This poster will first briefly introduce the water quality monitoring system, followed by the analysis of the advantages of the sub-hourly water quality data. Thus, the suggestion on the monitoring frequency will be given.

  2. Community Characteristics and Trajectories of Adolescent Internalizing and Externalizing Behaviors: The Cumulative Advantage/Disadvantage and Subjective Appraisals of Social Support as Mechanisms

    Zhang, Jing

    2012-01-01

    Studies examining neighborhood effects on adolescent outcomes have indicated that adolescents growing up in low-income neighborhoods are at higher risk of developing internalizing and externalizing behaviors. However, knowledge of the long-term effects of neighborhood disadvantages on internalizing and externalizing behaviors and the involved mechanisms across adolescence is limited. Using family life course theory and the cumulative advantage/disadvantage perspective, this study examined how...

  3. Possibility of applying mechanized coal mining in the mine 'Soko', with the comparative advantages of production results and impact

    Denić Miodrag

    2014-01-01

    Full Text Available Mining method applied in the RMU 'Soko', is repeatedly technologically modified and reached the maximum limit in terms of productivity, level of job performance and safety at work. And all the other methods, which are in the technological process of obtaining coal rely on the technology of drilling-blasting works, in terms of the mine 'Soko', can not allow mass production of coal, regarding natural and technical-technological conditions prevailing in Sokobanja coal basin. Therefore, this paper proposes a possible solution which would enable a significant increase in annual production by appling mechanized coal mining system.

  4. Advantages of using the CRISPR/Cas9 system of genome editing to investigate male reproductive mechanisms using mouse models.

    Young, Samantha A M; Aitken, R John; Ikawa, Masahito

    2015-01-01

    Gene disruption technology has long been beneficial for the study of male reproductive biology. However, because of the time and cost involved, this technology was not a viable method except in specialist laboratories. The advent of the CRISPR/Cas9 system of gene disruption has ushered in a new era of genetic investigation. Now, it is possible to generate gene-disrupted mouse models in very little time and at very little cost. This Highlight article discusses the application of this technology to study the genetics of male fertility and looks at some of the future uses of this system that could be used to reveal the essential and nonessential genetic components of male reproductive mechanisms.

  5. Advantages of the in-situ LTP distortion profile test on high-heat-load mirrors and applications

    Qian, S.; Jark, W.; Sostero, G.; Gambitta, A.; Mazzolini, F.; Savoia, A.

    1996-01-01

    The first in-situ distortion profile measurement of a high heat load mirror by use of the penta-prism LTP is presented. A maximum height distortion of 0.47 micron in tangential direction over a length of 180 mm was measured for an internally water-cooled mirror of a undulator beam line at ELETTRA while exposed to a total emitted power of 600 W (undulator gap 30 mm and current 180 mA). The experiment has an accuracy and repeatability of 0.04 micron. The test schematic and the test equipment are presented. Two measuring methods to scan a penta-prism being installed either outside or inside the vacuum chamber are introduced. Advantages and some possible applications of adopting the penta-prism LTP to make the in-situ profile test are explained

  6. Mechanical Properties of Organic Semiconductors for Stretchable, Highly Flexible, and Mechanically Robust Electronics.

    Root, Samuel E; Savagatrup, Suchol; Printz, Adam D; Rodriquez, Daniel; Lipomi, Darren J

    2017-05-10

    Mechanical deformability underpins many of the advantages of organic semiconductors. The mechanical properties of these materials are, however, diverse, and the molecular characteristics that permit charge transport can render the materials stiff and brittle. This review is a comprehensive description of the molecular and morphological parameters that govern the mechanical properties of organic semiconductors. Particular attention is paid to ways in which mechanical deformability and electronic performance can coexist. The review begins with a discussion of flexible and stretchable devices of all types, and in particular the unique characteristics of organic semiconductors. It then discusses the mechanical properties most relevant to deformable devices. In particular, it describes how low modulus, good adhesion, and absolute extensibility prior to fracture enable robust performance, along with mechanical "imperceptibility" if worn on the skin. A description of techniques of metrology precedes a discussion of the mechanical properties of three classes of organic semiconductors: π-conjugated polymers, small molecules, and composites. The discussion of each class of materials focuses on molecular structure and how this structure (and postdeposition processing) influences the solid-state packing structure and thus the mechanical properties. The review concludes with applications of organic semiconductor devices in which every component is intrinsically stretchable or highly flexible.

  7. Why solid-state fermentation is more advantageous over submerged fermentation for converting high concentration of glycerol into Monacolin K by Monascus purpureus 9901: A mechanistic study.

    Zhang, Bo-Bo; Lu, Li-Ping; Xu, Gan-Rong

    2015-07-20

    The underlying mechanisms by which solid-state fermentation (SSF) was more advantageous over submerged fermentation (SmF) for converting high concentration of glycerol into Monacolin K by Monascus purpureus were investigated innovatively. First, the established kinetic models and kinetic parameters showed that the cell growth, Monacolin K formation and glycerol consumption in SSF were more rapid than those in SmF. Secondly, the comparison of fatty acid composition of mycelial cells indicated a better fluidity and permeability of the cell membrane in SSF than that of SmF, which was also consistent with the difference in the ratio of extracellular/intracellular Monacolin K between the two systems. Thirdly, the phenomenon of glycerol concentration gradient was verified in SSF, which could well explain the resistance effect to high concentration of glycerol in SSF. These new findings provide some important insights to the elucidation of the advantages of SSF for the synthesis of fungal secondary metabolites. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Mechanisms for production of highly charged ions

    McGuire, J.H.

    1987-01-01

    Various experimental data at high collision velocity are interpreted in terms of direct (D) and rearrangement (R) mechanisms for production of multiply charged ions. We consider double ionization in helium by protons, electrons, heavy ions, antiprotons, positrons and photons. Qualitative differences are discussed in the context of the R and D mechanisms. Multiple ionization in many electron atoms is considered as is simultaneous capture and ionization and fragmentation of methane molecules. Some other theoretical methods are briefly discussed. (orig.)

  9. High temperature mechanical properties of iron aluminides

    Morris, D. G.; Munoz-Morris, M. A.

    2001-01-01

    Considerable attention has been given to the iron aluminide family of intermetallics over the past years since they offer considerable potential as engineering materials for intermediate to high temperature applications, particularly in cases where extreme oxidation or corrosion resistance is required. Despite efforts at alloy development, however, high temperature strength remains low and creep resistance poor. Reasons for the poor high-temperature strength of iron aluminides will be discussed, based on the ordered crystal structure, the dislocation structure found in the materials, and the mechanisms of dislocation pinning operating. Alternative ways of improving high temperature strength by microstructural modification and the inclusion of second phase particles will also be considered. (Author)

  10. Educational advantage.

    2013-07-01

    of interest in being informed before participating in a survey on a highly sensitive topic. For those of us who would unthinkingly impose standard Western consent procedures on everyone, these four articles may have much to teach us.

  11. The application of cryogenics to high Reynolds number testing in wind tunnels. I - Evolution, theory, and advantages

    Kilgore, R. A.; Dress, D. A.

    1984-01-01

    During the time which has passed since the construction of the first wind tunnel in 1870, wind tunnels have been developed to a high degree of sophistication. However, their development has consistently failed to keep pace with the demands placed on them. One of the more serious problems to be found with existing transonic wind tunnels is their inability to test subscale aircraft models at Reynolds numbers sufficiently near full-scale values to ensure the validity of using the wind tunnel data to predict flight characteristics. The Reynolds number capability of a wind tunnel may be increased by a number of different approaches. However, the best solution in terms of model, balance, and model support loads, as well as in terms of capital and operating cost appears to be related to the reduction of the temperature of the test gas to cryogenic temperatures. The present paper has the objective to review the evolution of the cryogenic wind tunnel concept and to describe its more important advantages.

  12. Nonextensive statistical mechanics and high energy physics

    Tsallis Constantino

    2014-04-01

    Full Text Available The use of the celebrated Boltzmann-Gibbs entropy and statistical mechanics is justified for ergodic-like systems. In contrast, complex systems typically require more powerful theories. We will provide a brief introduction to nonadditive entropies (characterized by indices like q, which, in the q → 1 limit, recovers the standard Boltzmann-Gibbs entropy and associated nonextensive statistical mechanics. We then present somerecent applications to systems such as high-energy collisions, black holes and others. In addition to that, we clarify and illustrate the neat distinction that exists between Lévy distributions and q-exponential ones, a point which occasionally causes some confusion in the literature, very particularly in the LHC literature

  13. Mechanical reliability of bulk high Tc superconductors

    Freiman, S.W.

    1990-01-01

    Most prospective applications for high T c superconductors in bulk form, e.g. magnets, motors, will require appreciable mechanical strength. Work at NIST [National Institute of Standards and Technology] has begun to address issues related to mechanical reliability. For example, recent studies on Ba-Y-Cu-O have shown that the intrinsic crack growth resistance, K IC , of crystals of this material is even smaller than was first reported, less than that of window glass, and is sensitive to moisture. Processing conditions, particularly sintering and annealing atmosphere, have been shown to have a major influence on microstructure and internal stresses in the material. Large internal stresses result from the tetragonal to orthorhombic phase transformation as well as the thermal expansion anisotropy in the grains of the ceramic. Because stress relief is absent, microcracks form which have a profound influence on strength

  14. Mechanical properties of high-strength concrete

    Mokhtarzadeh, Alireza

    This report summarizes an experimental program conducted to investigate production techniques and mechanical properties of high strength concrete in general and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. Test variables included total amount and composition of cementitious material (portland cement, fly ash, and silica fume), type and brand of cement, type of silica fume (dry densified and slurry), type and brand of high-range water-reducing admixture, type of aggregate, aggregate gradation, maximum aggregate size, and curing. Tests were conducted to determine the effects of these variables on changes in compressive strength and modulus of elasticity over time, splitting tensile strength, modulus of rupture, creep, shrinkage, and absorption potential (as an indirect indicator of permeability). Also investigated were the effects of test parameters such as mold size, mold material, and end condition. Over 6,300 specimens were cast from approximately 140 mixes over a period of 3 years.

  15. Balanced bilingualism and early age of second language acquisition as the underlying mechanisms of a bilingual executive control advantage: why variations in bilingual experiences matter

    Yow, W. Quin; Li, Xiaoqian

    2015-01-01

    Recent studies revealed inconsistent evidences of a bilingual advantage in executive processing. One potential source of explanation is the multifaceted experience of the bilinguals in these studies. This study seeks to test whether bilinguals who engage in language selection more frequently would perform better in executive control tasks than those bilinguals who engage in language selection less frequently. We examined the influence of the degree of bilingualism (i.e., language proficiency, frequency of use of two languages, and age of second language acquisition) on executive functioning in bilingual young adults using a comprehensive battery of executive control tasks. Seventy-two 18- to 25-years-old English–Mandarin bilinguals performed four computerized executive function (EF) tasks (Stroop, Eriksen flanker, number–letter switching, and n-back task) that measure the EF components: inhibition, mental-set shifting, and information updating and monitoring. Results from multiple regression analyses, structural equation modeling, and bootstrapping supported the positive association between age of second language acquisition and the interference cost in the Stroop task. Most importantly, we found a significant effect of balanced bilingualism (balanced usage of and balanced proficiency in two languages) on the Stroop and number–letter task (mixing cost only), indicating that a more balanced use and a more balanced level of proficiency in two languages resulted in better executive control skills in the adult bilinguals. We did not find any significant effect of bilingualism on flanker or n-back task. These findings provided important insights to the underlying mechanisms of the bilingual cognitive advantage hypothesis, demonstrating that regular experience with extensive practice in controlling attention to their two language systems results in better performance in related EFs such as inhibiting prepotent responses and global set-shifting. PMID:25767451

  16. Balanced bilingualism and early age of second language acquisition as the underlying mechanisms of a bilingual executive control advantage: why variations in bilingual experiences matter.

    Yow, W Quin; Li, Xiaoqian

    2015-01-01

    Recent studies revealed inconsistent evidences of a bilingual advantage in executive processing. One potential source of explanation is the multifaceted experience of the bilinguals in these studies. This study seeks to test whether bilinguals who engage in language selection more frequently would perform better in executive control tasks than those bilinguals who engage in language selection less frequently. We examined the influence of the degree of bilingualism (i.e., language proficiency, frequency of use of two languages, and age of second language acquisition) on executive functioning in bilingual young adults using a comprehensive battery of executive control tasks. Seventy-two 18- to 25-years-old English-Mandarin bilinguals performed four computerized executive function (EF) tasks (Stroop, Eriksen flanker, number-letter switching, and n-back task) that measure the EF components: inhibition, mental-set shifting, and information updating and monitoring. Results from multiple regression analyses, structural equation modeling, and bootstrapping supported the positive association between age of second language acquisition and the interference cost in the Stroop task. Most importantly, we found a significant effect of balanced bilingualism (balanced usage of and balanced proficiency in two languages) on the Stroop and number-letter task (mixing cost only), indicating that a more balanced use and a more balanced level of proficiency in two languages resulted in better executive control skills in the adult bilinguals. We did not find any significant effect of bilingualism on flanker or n-back task. These findings provided important insights to the underlying mechanisms of the bilingual cognitive advantage hypothesis, demonstrating that regular experience with extensive practice in controlling attention to their two language systems results in better performance in related EFs such as inhibiting prepotent responses and global set-shifting.

  17. Balanced bilingualism and early age of second language acquisition as the underlying mechanisms of a bilingual executive control advantage: Why variations in bilingual experiences matter.

    W. Quin eYow

    2015-02-01

    Full Text Available Recent studies revealed inconsistent evidences of a bilingual advantage in executive processing. One potential source of explanation is the multifaceted experience of the bilinguals in these studies. This study seeks to test whether bilinguals who engage in language selection more frequently would perform better in executive control tasks than those bilinguals who engage in language selection less frequently. We examined the influence of the degree of bilingualism (i.e., language proficiency, frequency of use of two languages, and age of second language acquisition on executive functioning in bilingual young adults using a comprehensive battery of executive control tasks. Seventy-two 18- to 25-year-old English-Mandarin bilinguals performed four computerized executive function tasks (Stroop, Eriksen flanker, number-letter switching and n-back task that measure the executive function components: inhibition, mental-set shifting, and information updating and monitoring. Results from multiple regression analyses, structural equation modeling, and bootstrapping supported the positive association between age of second language acquisition and the interference cost in the Stroop task. Most importantly, we found a significant effect of balanced bilingualism (balanced usage of and balanced proficiency in two languages on the Stroop and number-letter task (mixing cost only, indicating that a more balanced use and a more balanced level of proficiency in two languages resulted in better executive control skills in the adult bilinguals. We did not find any significant effect of bilingualism on flanker or n-back task. These findings provided important insights to the underlying mechanisms of the bilingual cognitive advantage hypothesis, demonstrating that regular experience with extensive practice in controlling attention to their two language systems results in better performance in related executive functions such as inhibiting prepotent responses and global

  18. Mechanisms of conventional and high Tc superconductivity

    Kresin, V.L.; Morawitz, H.; Wolf, S.A.

    1993-01-01

    This book gives a careful and objective review of theories of superconductivity in traditional superconductors, organics, and high Tc cuprates. Of course, the authors do still present their own theories of cuprate superconductivity, but only in the final chapter after other possibilities have been discussed. The book should be especially useful for researchers entering the field of high Tc superconductivity. The reviews of photon mediated pairing and strong coupling theory are very welcome, since much of this material has not been reviewed since the classic 1969 volume edited by Parks. In particular the authors dispel the various myths that phonon mediated pairing leads to upper bounds on Tc. In addition to phonon mediated pairing the book discussed in detail pairing due to exchange of acoustic (demon) plasmons, excitons, or magnetic fluctuations. There have been so many diverse mechanisms based on strong correlation and large U Hubbard models that a book like this can only discuss a limited selection of the main contenders. In particular here the emphasis on Fermi liquid based models no doubt reflects the authors' own point of view. A whole chapter discusses the concepts of induced superconductivity, in the proximity effect, and its application to materials with several different electronic subsystems

  19. High temperature mechanical forming of Mg alloys

    Mwembela, A.; McQueen, H.J.; Myshlyaev, M.

    2002-01-01

    Mg alloys are hot worked in the range 180-450 o C and 0.0-10 s -1 ; the present project data are compared with a wide selection of published results. The flow stresses and their dependence on temperature and strain rate are fairly similar to simple Al alloys: however, the hot ductility is much lower (≤3 in torsion). Twinning plays a significant role in Mg alloys almost independently of temperature; the twins initiate at low strains in grains poorly oriented for basal slip and in consequence become well disposed for such slip. As T rises, there is increasing formation of subgrains that spread toward the grain centers from grain and twin boundaries: this is indicative of stress concentrations inducing non-basal sup which helps provide the geometrically necessary dislocations. Above about 240 o C, dynamic (DRX) nucleates at grain and twin boundaries, preferentially at intersections; this again is evidence of non-basal slip that provides the highly misoriented cells. The boundaries in which further strain concentrates producing further DRX. The microstructure remains very heterogeneous compared to the uniform dynamically recovered substructure in Al alloys, thus giving rise to the reduced ductility. These results are employed to interpret the mechanical and microstructural behavior of Mg alloys in extrusion, rolling and forging. (author)

  20. Damage Mechanisms and Mechanical Properties of High-Strength Multiphase Steels

    Sebastian Heibel

    2018-05-01

    Full Text Available The usage of high-strength steels for structural components and reinforcement parts is inevitable for modern car-body manufacture in reaching lightweight design as well as increasing passive safety. Depending on their microstructure these steels show differing damage mechanisms and various mechanical properties which cannot be classified comprehensively via classical uniaxial tensile testing. In this research, damage initiation, evolution and final material failure are characterized for commercially produced complex-phase (CP and dual-phase (DP steels in a strength range between 600 and 1000 MPa. Based on these investigations CP steels with their homogeneous microstructure are characterized as damage tolerant and hence less edge-crack sensitive than DP steels. As final fracture occurs after a combination of ductile damage evolution and local shear band localization in ferrite grains at a characteristic thickness strain, this strain measure is introduced as a new parameter for local formability. In terms of global formability DP steels display advantages because of their microstructural composition of soft ferrite matrix including hard martensite particles. Combining true uniform elongation as a measure for global formability with the true thickness strain at fracture for local formability the mechanical material response can be assessed on basis of uniaxial tensile testing incorporating all microstructural characteristics on a macroscopic scale. Based on these findings a new classification scheme for the recently developed high-strength multiphase steels with significantly better formability resulting of complex underlying microstructures is introduced. The scheme overcomes the steel designations using microstructural concepts, which provide no information about design and production properties.

  1. Mechanical properties of rock at high temperatures

    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)

  2. Diagnostic relevance of high field MRI in clinical neuroradiology: the advantages and challenges of driving a sports car

    Wattjes, Mike P.; Barkhof, Frederik

    2012-01-01

    High field MRI operating at 3 T is increasingly being used in the field of neuroradiology on the grounds that higher magnetic field strength should theoretically lead to a higher diagnostic accuracy in the diagnosis of several disease entities. This Editorial discusses the exhaustive review by Wardlaw and colleagues of research comparing 3 T MRI with 1.5 T MRI in the field of neuroradiology. Interestingly, the authors found no convincing evidence of improved image quality, diagnostic accuracy, or reduced total examination times using 3 T MRI instead of 1.5 T MRI. These findings are highly relevant since a new generation of high field MRI systems operating at 7 T has recently been introduced. (orig.)

  3. High pressure does not counterbalance the advantages of open techniques over closed techniques during heated intraperitoneal chemotherapy with oxaliplatin.

    Facy, Olivier; Combier, Christophe; Poussier, Matthieu; Magnin, Guy; Ladoire, Sylvain; Ghiringhelli, François; Chauffert, B; Rat, Patrick; Ortega-Deballon, Pablo

    2015-01-01

    Heated intraperitoneal chemotherapy (HIPEC) treats residual microscopic disease after cytoreductive surgery. In experimental models, the open HIPEC technique has shown a higher and more homogenous concentration of platinum in the peritoneum than achieved using the closed technique. A 25-cm H2O pressure enhances the penetration of oxaliplatin. Because pressure is easier to set up with the closed technique, high pressure may counterbalance the drawbacks of this technique versus open HIPEC, and a higher pressure may induce a higher penetration. Because higher concentration does not mean deeper penetration, a study of tissues beneath the peritoneum is required. Finally, achieving a deeper penetration (and a higher concentration) raises the question of the passage of drugs through the surgical glove and the surgeon's safety. Four groups of pigs underwent HIPEC with oxaliplatin (150 mg/L) for 30 minutes in open isobaric pressure and pressure at 25 cm H2O, and closed pressure at 25 and 40 cm H2O. Systemic absorption and peritoneal mapping of the concentration of platinum were analyzed, as well as in the retroperitoneal tissue and the surgical gloves. Blood concentrations were higher in open groups. In the parietal surfaces, the concentrations were not different between the isobaric and the closed groups (47.08, 56.39, and 48.57 mg/kg, respectively), but were higher in the open high-pressure group (85.93 mg/kg). In the visceral surfaces, they were lower in the closed groups (3.2 and 3.05 mg/kg) than in the open groups (7.03 and 9.56 mg/kg). Platinum concentrations were similar in the deep retroperitoneal tissue when compared between isobaric and high-pressure procedures. No platin was detected in the internal aspect of the gloves. The use of high pressure during HIPEC does not counterbalance the drawbacks of closed techniques. The tissue concentration of oxaliplatin achieved with the open techniques is higher, even if high pressure is applied during a closed technique

  4. Exploiting Process-Related Advantages of Selective Laser Melting for the Production of High-Manganese Steel.

    Haase, Christian; Bültmann, Jan; Hof, Jan; Ziegler, Stephan; Bremen, Sebastian; Hinke, Christian; Schwedt, Alexander; Prahl, Ulrich; Bleck, Wolfgang

    2017-01-11

    Metal additive manufacturing has strongly gained scientific and industrial importance during the last decades due to the geometrical flexibility and increased reliability of parts, as well as reduced equipment costs. Within the field of metal additive manufacturing methods, selective laser melting (SLM) is an eligible technique for the production of fully dense bulk material with complex geometry. In the current study, we addressed the application of SLM for processing a high-manganese TRansformation-/TWinning-Induced Plasticity (TRIP/TWIP) steel. The solidification behavior was analyzed by careful characterization of the as-built microstructure and element distribution using optical and scanning electron microscopy (SEM). In addition, the deformation behavior was studied using uniaxial tensile testing and SEM. Comparison with conventionally produced TRIP/TWIP steel revealed that elemental segregation, which is normally very pronounced in high-manganese steels and requires energy-intensive post processing, is reduced due to the high cooling rates during SLM. Also, the very fast cooling promoted ε- and α'-martensite formation prior to deformation. The superior strength and pronounced anisotropy of the SLM-produced material was correlated with the microstructure based on the process-specific characteristics.

  5. Exploiting Process-Related Advantages of Selective Laser Melting for the Production of High-Manganese Steel

    Christian Haase

    2017-01-01

    Full Text Available Metal additive manufacturing has strongly gained scientific and industrial importance during the last decades due to the geometrical flexibility and increased reliability of parts, as well as reduced equipment costs. Within the field of metal additive manufacturing methods, selective laser melting (SLM is an eligible technique for the production of fully dense bulk material with complex geometry. In the current study, we addressed the application of SLM for processing a high-manganese TRansformation-/TWinning-Induced Plasticity (TRIP/TWIP steel. The solidification behavior was analyzed by careful characterization of the as-built microstructure and element distribution using optical and scanning electron microscopy (SEM. In addition, the deformation behavior was studied using uniaxial tensile testing and SEM. Comparison with conventionally produced TRIP/TWIP steel revealed that elemental segregation, which is normally very pronounced in high-manganese steels and requires energy-intensive post processing, is reduced due to the high cooling rates during SLM. Also, the very fast cooling promoted ε- and α’-martensite formation prior to deformation. The superior strength and pronounced anisotropy of the SLM-produced material was correlated with the microstructure based on the process-specific characteristics.

  6. Mechanical behavior of high strength ceramic fibers at high temperatures

    Tressler, R. E.; Pysher, D. J.

    1991-01-01

    The mechanical behavior of commercially available and developmental ceramic fibers, both oxide and nonoxide, has been experimentally studied at expected use temperatures. In addition, these properties have been compared to results from the literature. Tensile strengths were measured for three SiC-based and three oxide ceramic fibers for temperatures from 25 C to 1400 C. The SiC-based fibers were stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures. Extensive creep and creep-rupture experiments have been performed on those fibers from this group which had the best strengths above 1200 C in both single filament tests and tests of fiber bundles. The creep rates for the oxides are on the order of two orders of magnitude faster than the polymer derived nonoxide fibers. The most creep resistant filaments available are single crystal c-axis sapphire filaments. Large diameter CVD fabricated SiC fibers are the most creep and rupture resistant nonoxide polycrystalline fibers tested to date.

  7. Competitive versus comparative advantage

    Neary, J. Peter

    2002-01-01

    I explore the interactions between comparative, competitive and absolute advantage in a two-country model of oligopoly in general equilibrium. Comparative advantage always determines the direction of trade, but both competitive and absolute advantage affect resource allocation, trade patterns and trade volumes. Competitive advantage in the sense of more home firms drives foreign firms out of marginal sectors but also makes some marginal home sectors uncompetitive. Absolute advantage in the se...

  8. Colorimetric Chemical Differentiation and Detection of Phosphorus in Eutrophic and High Particulate Waters: Advantages of a New Monitoring Approach

    Lisa Felgentreu

    2018-06-01

    Full Text Available Phosphorus (P is a key factor forcing eutrophication in limnic and marine systems, and all monitoring programs for water quality accordingly include P determinations. However, traditional monitoring does not allow an analysis of the different components involved in the P cycle taking place in the water column. Nonetheless, the implementation of measures addressing eutrophication requires a full understanding of the processes involved in the transformation and transport of P, in all its chemical forms. In this study, the P categories present in a river and its estuary in northern Germany, which discharge into the Baltic Sea, were characterized. Using the molybdenum blue method we found that the classification of P into the traditional fractions (DIP, DOP, POP applied in the ocean cannot be applied to turbid waters such as rivers because interferences between the fractions seems to occur. Therefore a new nomenclature has been introduced. In addition to total phosphorus (TP and dissolved molybdate-reactive phosphorus (DRP; previously referred to as inorganic phosphorus, dissolved non-molybdate-reactive phosphorus (DNP, particulate molybdatereactive phosphorus (PRP, and particulate non-molybdate-reactive phosphorus (PNP were distinguished. The high spatial and temporal variations in the proportions of these forms with respect to the TP concentration well-demonstrate the complexity of the P cycle and the involved P fractions and emphasize the need for expanded monitoring approach. The potential of eutrophication could be underestimated if not all P categories were considered. With the new operational nomenclature the common and standardized molybdenum blue reaction could be used to implement the analysis of various P components into regular monitoring programs.

  9. Creating corporate advantage.

    Collis, D J; Montgomery, C A

    1998-01-01

    What differentiates truly great corporate strategies from the merely adequate? How can executives at the corporate level create tangible advantage for their businesses that makes the whole more than the sum of the parts? This article presents a comprehensive framework for value creation in the multibusiness company. It addresses the most fundamental questions of corporate strategy: What businesses should a company be in? How should it coordinate activities across businesses? What role should the corporate office play? How should the corporation measure and control performance? Through detailed case studies of Tyco International, Sharp, the Newell Company, and Saatchi and Saatchi, the authors demonstrate that the answers to all those questions are driven largely by the nature of a company's special resources--its assets, skills, and capabilities. These range along a continuum from the highly specialized at one end to the very general at the other. A corporation's location on the continuum constrains the set of businesses it should compete in and limits its choices about the design of its organization. Applying the framework, the authors point out the common mistakes that result from misaligned corporate strategies. Companies mistakenly enter businesses based on similarities in products rather than the resources that contribute to competitive advantage in each business. Instead of tailoring organizational structures and systems to the needs of a particular strategy, they create plain-vanilla corporate offices and infrastructures. The company examples demonstrate that one size does not fit all. One can find great corporate strategies all along the continuum.

  10. Carbon Nanofiber-Based, High-Frequency, High-Q, Miniaturized Mechanical Resonators

    Kaul, Anupama B.; Epp, Larry W.; Bagge, Leif

    2011-01-01

    High Q resonators are a critical component of stable, low-noise communication systems, radar, and precise timing applications such as atomic clocks. In electronic resonators based on Si integrated circuits, resistive losses increase as a result of the continued reduction in device dimensions, which decreases their Q values. On the other hand, due to the mechanical construct of bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators, such loss mechanisms are absent, enabling higher Q-values for both BAW and SAW resonators compared to their electronic counterparts. The other advantages of mechanical resonators are their inherently higher radiation tolerance, a factor that makes them attractive for NASA s extreme environment planetary missions, for example to the Jovian environments where the radiation doses are at hostile levels. Despite these advantages, both BAW and SAW resonators suffer from low resonant frequencies and they are also physically large, which precludes their integration into miniaturized electronic systems. Because there is a need to move the resonant frequency of oscillators to the order of gigahertz, new technologies and materials are being investigated that will make performance at those frequencies attainable. By moving to nanoscale structures, in this case vertically oriented, cantilevered carbon nanotubes (CNTs), that have larger aspect ratios (length/thickness) and extremely high elastic moduli, it is possible to overcome the two disadvantages of both bulk acoustic wave (BAW) and surface acoustic wave (SAW) resonators. Nano-electro-mechanical systems (NEMS) that utilize high aspect ratio nanomaterials exhibiting high elastic moduli (e.g., carbon-based nanomaterials) benefit from high Qs, operate at high frequency, and have small force constants that translate to high responsivity that results in improved sensitivity, lower power consumption, and im - proved tunablity. NEMS resonators have recently been demonstrated using topdown

  11. High-pressure mechanical instability in rocks.

    Byerlee, J D; Brace, W F

    1969-05-09

    At a confining pressure of a few kilobars, deformation of many sedimentary rocks, altered mafic rocks, porous volcanic rocks, and sand is ductile, in that instabilities leading to audible elastic shocks are absent. At pressures of 7 to 10 kilobars, however, unstable faulting and stick-slip in certain of these rocks was observed. This high pressure-low temperature instability might be responsible for earthquakes in deeply buried sedimentary or volcanic sequences.

  12. High relative humidity in-package of fresh-cut fruits and vegetables: advantage or disadvantage considering microbiological problems and antimicrobial delivering systems?

    Ayala-Zavala, J F; Del-Toro-Sánchez, L; Alvarez-Parrilla, E; González-Aguilar, G A

    2008-05-01

    This hypothesis article states that the high relative humidity (RH) of packaged fresh-cut fruits or vegetables that is associated with spoilage can be used as an advantageous way to deliver antimicrobial compounds using cyclodextrins (CDs) as carriers. CDs can function as antimicrobial delivery systems as they can release antioxidant and antimicrobial compounds (guest molecules) as the humidity levels increase in the headspace. Hydrophobic antimicrobial guests can be complexed with CDs due to the amphiphatic nature of the host. Then, at high RH values, due to the water-CDs interaction, host-guest interactions are weakened; consequently, the antimicrobial molecule is released and should protect the product against the microbial growth. Potential antimicrobial compounds capable of forming complexes with CDs are discussed, as well as possible applications to preserve fresh-cut produce and future research in this area.

  13. Brokers and Competitive Advantage

    Michael D. Ryall; Olav Sorenson

    2007-01-01

    The broker profits by intermediating between two (or more) parties. Using a biform game, we examine whether such a position can confer a competitive advantage, as well as whether any such advantage could persist if actors formed relations strategically. Our analysis reveals that, if one considers exogenous the relations between actors, brokers can enjoy an advantage but only if (1) they do not face substitutes either for the connections they offer or the value they can create, (2) they interm...

  14. Mechanical properties of concrete for power reactor at high temperatures

    Kawase, Kiyotaka; Tanaka, Hitoshi; Nakano, Masayuki

    1985-01-01

    The purpose of this study is to investigate the mechanical properties of concrete for power reactor at high temperature. This paper presents the creep behavior of concrete at high temperature and the cause by which a specified aggregate is broken at a specified high temperature. The creep coefficient at high temperature is smaller than that at ordinary temperature. (author)

  15. Development of LTCC Materials with High Mechanical Strength

    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.

  16. Imaging with organic indicators and high-speed charge-coupled device cameras in neurons: some applications where these classic techniques have advantages.

    Ross, William N; Miyazaki, Kenichi; Popovic, Marko A; Zecevic, Dejan

    2015-04-01

    Dynamic calcium and voltage imaging is a major tool in modern cellular neuroscience. Since the beginning of their use over 40 years ago, there have been major improvements in indicators, microscopes, imaging systems, and computers. While cutting edge research has trended toward the use of genetically encoded calcium or voltage indicators, two-photon microscopes, and in vivo preparations, it is worth noting that some questions still may be best approached using more classical methodologies and preparations. In this review, we highlight a few examples in neurons where the combination of charge-coupled device (CCD) imaging and classical organic indicators has revealed information that has so far been more informative than results using the more modern systems. These experiments take advantage of the high frame rates, sensitivity, and spatial integration of the best CCD cameras. These cameras can respond to the faster kinetics of organic voltage and calcium indicators, which closely reflect the fast dynamics of the underlying cellular events.

  17. Scandinavian Cooperative Advantage

    Strand, Robert; Freeman, R. Edward

    2015-01-01

    . We conclude by endorsing the expression “Scandinavian cooperative advantage” in an effort to draw attention to the Scandinavian context and encourage the field of strategic management to shift its focus from achieving a competitive advantage toward achieving a cooperative advantage....

  18. Accessing offshoring advantages

    Mykhaylenko, Alona; Motika, Agnes; Wæhrens, Brian Vejrum

    2015-01-01

    . Assuming that different levels of synergy may exist between particular offshoring strategic decisions (choosing offshore outsourcing or captive offshoring and the type of function) and different offshoring advantages, this work advocates that the actual fact of realization of certain offshoring advantages...

  19. A novel in vitro model for hematogenous spreading of S. aureus device biofilms demonstrating clumping dispersal as an advantageous dissemination mechanism

    Grønnemose, Rasmus Birkholm; Lindhardt Sæderup (Madsen), Kirstine; Kolmos, Hans Jørn

    2017-01-01

    Staphylococcus aureus is able to disseminate from vascular device biofilms to the blood and organs, resulting in life-threatening infections such as endocarditis. The mechanisms behind spreading are largely unknown, especially how the bacterium escapes immune effectors and antibiotics in the proc......Staphylococcus aureus is able to disseminate from vascular device biofilms to the blood and organs, resulting in life-threatening infections such as endocarditis. The mechanisms behind spreading are largely unknown, especially how the bacterium escapes immune effectors and antibiotics...... the ability to adhere to and initiate colonization of endothelial cell layers under flow. In vivo experiments showed that the released biofilm material reached the heart similarly as ordinary broth-grown bacteria, but also that clumps to some extend were trapped in the lungs. The clumping dispersal of S....... aureus from in vivo-like vascular biofilms and their specific properties demonstrated here help explain the pathophysiology associated with S. aureus bloodstream infections....

  20. Resonance charge exchange mechanism at high and moderate energies

    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

  1. Failure mechanisms in high temperature gas cooled reactor fuel particles

    Soo, P.; Uneberg, G.; Sabatini, R.L.; Schweitzer, D.G.

    1979-01-01

    BISO coated UO 2 and ThO 2 particles were heated to high temperatures to determine failure mechanisms during hypothetical loss of coolant scenarios. Rapid failure begins when the oxides are reduced to liquid carbides. Several failure mechanisms are applicable, ranging from hole and crack formation in the coatings to catastrophic particle disintegration

  2. Gaining Relational Competitive Advantages

    Hu, Yimei; Zhang, Si; Li, Jizhen

    2015-01-01

    Establishing strategic technological partnerships (STPs) with foreign partners is an increasingly studied topic within the innovation management literature. Partnering firms can jointly create sources of relational competitive advantage. Chinese firms often lack research and development (R......&D) capabilities but are increasingly becoming preferred technological partners for transnational corporations. We investigate an STP between a Scandinavian and a Chinese firm and try to explore how to gain relational competitive advantage by focusing on its two essential stages: relational rent generation...... and appropriation. Based on an explorative case study, we develop a conceptual framework that consists of process, organizational alliance factors, and coordination modes that we propose lead to relational competitive advantage....

  3. New advantages of the combined GPS and GLONASS observations for high-latitude ionospheric irregularities monitoring: case study of June 2015 geomagnetic storm

    Cherniak, Iurii; Zakharenkova, Irina

    2017-05-01

    Monitoring, tracking and nowcasting of the ionospheric plasma density disturbances using dual-frequency measurements of the Global Positioning System (GPS) signals are effectively carried out during several decades. Recent rapid growth and modernization of the ground-based segment gives an opportunity to establish a great database consisting of more than 6000 stations worldwide which provide GPS signals measurements with an open access. Apart of the GPS signals, at least two-third of these stations receive simultaneously signals transmitted by another Global Navigation Satellite System (GNSS)—the Russian system GLONASS. Today, GLONASS signal measurements are mainly used in navigation and geodesy only and very rarely for ionosphere research. We present the first results demonstrating advantages of using several independent but compatible GNSS systems like GPS and GLONASS for improvement of the permanent monitoring of the high-latitude ionospheric irregularities. For the first time, the high-resolution two-dimensional maps of ROTI perturbation were made using not only GPS but also GLONASS measurements. We extend the use of the ROTI maps for analyzing ionospheric irregularities distribution. We demonstrate that the meridional slices of the ROTI maps can be effectively used to study the occurrence and temporal evolution of the ionospheric irregularities. The meridional slices of the geographical sectors with a high density of the GPS and GLONASS measurements can represent spatio-temporal dynamics of the intense ionospheric plasma density irregularities with very high resolution, and they can be effectively used for detailed study of the space weather drivers on the processes of the ionospheric irregularities generation, development and their lifetimes. Using a representative database of 5800 ground-based GNSS stations located worldwide, we have investigated the occurrence of the high-latitude ionospheric plasma density irregularities during the geomagnetic storm of

  4. Effect of resin composition to the electrical and mechanical properties of high voltage insulator material

    Totok Dermawan; Elin Nuraini; Suyamto

    2012-01-01

    A solid insulator manufacture of resins for high voltage with a variation of resin and hardener composition has been made. The purpose of research to know electrical and mechanical properties of high voltage insulator material of resin. To determine its electric properties, the material is tested its breakdown voltage and the flashover voltage that occurred on the surface. While to determine the mechanical properties were tested by measuring its strength with a tensile test. From testing with variety of mixed composition it is known that for composition between hardener and resin of 1 : 800 has most advantageous properties because it has good strength with a tensile strength of 19.86 MPa and enough high dielectric strength of 43.2 kV / mm). (author)

  5. New diffusion mechanism for high temperature diffusion in solids

    Doan, N.V.; Adda, Y.

    1986-09-01

    A new atomic transport mechanism in solids at high temperatures has been discovered by Molecular Dynamics computer simulation. It can be described as a ring sequence of atomic replacements induced by unstable Frenkel pairs. This transport process takes place without stable defects, the atomic migration occurring indeed by simultaneous creation and migration of unstable defects. Starting from the analysis of this mechanism in different solids at high temperature (CaF 2 , Na, Ar) and in irradiated copper by subthreshold collisions, we discuss the role of this mechanism on various diffusion controlled phenomena and also on the atomic processes of defect creation

  6. High-temperature mechanical and material design for SiC composites

    Ghoniem, N.M.

    1992-01-01

    Silicon Carbide (SiC) fiber reinforced composites (FRC's) are strong potential candidate structural and high heat flux materials for fusion reactors. During this past decade, they have been vigorously developed for use in aerospace and transportation applications. Recent fusion reactor systems studies, such as ARIES, have concluded that further development of SiC composites will result in significant safety, operational, and waste disposal advantages for fusion systems. A concise discussion of the main material and design issues related to the use of SiC FRC's as structural materials in future fusion systems is given in this paper. The status of material processing of SiC/SiC composites is first reviewed. The advantages and shortcomings of the leading processing technology, known as Chemical Vapor Infiltration are particularly highlighted. A brief outline of the design-relevant physical, mechanical, and radiation data base is then presented. SiC/SiC FRC's possess the advantage of increased apparent toughness under mechanical loading conditions. This increased toughness, however, is associated with the nucleation and propagation of small crack patterns in the structure. Design approaches and failure criteria under these conditions are discussed

  7. Advantages of floating covers with LLDPE Liners

    Munoz Gomez, J. M.

    2014-01-01

    Using floating covers in irrigation pounds and waste dam gives many advantages. It is a very interesting investment for those place with a high evaporation ratio. this is an easy system which improves several aspects in irrigation or drinkable water reservoirs, mainly it saves water and it saves clean-works (time and cost). It is also used in waste dam to deodorization. Time ago this application was developed with PVC liners and TPO liners, now the innovation is LLDPE liners which improve mechanical properties, durability and an easier installation. This paper develops the state of art of this design technology, and the back ground of our experience. (Author)

  8. Advantages of later motherhood.

    Myrskylä, M; Barclay, K; Goisis, A

    2017-01-01

    In high-income countries childbearing has been increasingly postponed since the 1970s and it is crucial to understand the consequences of this demographic shift. The literature has tended to characterize later motherhood as a significant health threat for children and parents. We contribute to this debate by reviewing recent evidence suggesting that an older maternal age can also have positive effects. Literature linking the age at parenthood with the sociodemographic characteristics of the parents, with macrolevel interactions, and with subjective well-being. Comprehensive review of the existing literature. Recent studies show that there can also be advantages associated with later motherhood. First, whilst in past older mothers had low levels of education and large families, currently older mothers tend to have higher education and smaller families than their younger peers. Consequently, children born to older mothers in the past tended to have worse outcomes than children born to younger mothers, whilst the opposite is true in recent cohorts. Second, postponement of childbearing means that the child is born at a later date and in a later birth cohort, and may benefit from secular changes in the macroenvironment. Evidence shows that when the positive trends in the macroenvironment are strong they overweigh the negative effects of reproductive ageing. Third, existing studies show that happiness increases around and after childbirth among older mothers, whereas for younger mothers the effect does not exist or is short-lived. There are important sociodemographic pathways associated with postponement of childbearing which might compensate or even more than compensate for the biological disadvantages associated with reproductive ageing.

  9. Effect of high thermal expansion glass infiltration on mechanical ...

    This work studies the effect on the mechanical properties of alumina-10 wt% zirconia (3 mol% yttria stabilized) composite by infiltrating glass of a higher thermal expansion (soda lime glass) on the surface at high temperature. The glass improved the strength of composite at room temperature as well as at high temperature.

  10. Mechanical Properties of High Performance Cementitious Grout (II)

    Sørensen, Eigil V.

    The present report is an update of the report “Mechanical Properties of High Performance Cementitious Grout (I)” [1] and describes tests carried out on the high performance grout MASTERFLOW 9500, marked “WMG 7145 FP”, developed by BASF Construction Chemicals A/S and designed for use in grouted...

  11. COMPETITIVE PRODUCT ADVANTAGES

    Adrian MICU

    2006-01-01

    Full Text Available Cost advantages may be either internal or external. Internal economics of scope, scale, or experience, and external economies of focus or logistical integration, enable a company to produce some products at a lower cost than the competition. The coordination of pricing with suppliers, although not actually economizing resources, can improve the efficiency of pricing by avoiding the incrementalization of a supplier's nonincremental fixed costs and profit. Any of these strategies can generate cost advantages that are, at least in the short run, sustainable. Even cost advantages that are not sustainable, however, can generate temporary savings that are often the key to building more sustainable cost or product advantages later.. Even when a product's physical attributes are not readily differentiable, opportunities to develop product advantages remain. The augmented product that customers buy is more than the particular product or service exchanged. It includes all sorts of ancillary services and intangible relationships that make buying thesame product from one company less difficult, less risky, or more pleasant than buying from a competitor. Superior augmentation of the same basic product can add substantial value in the eyes of consumers, leading them to pay willingly what are often considerable price premiums.

  12. Compositional Advantage and Strategy

    Li, Xin

    advantage is redefined as the attractiveness of the composition of the producer’s offering in terms of scope and perceived value/price ratio. I identify five ways or basic compositional strategies to improve the value/price ratio. A firm may have an overall compositional strategy that is composed of some......In this paper, I first critique the composition-based view of Yadong Luo and John Child for understanding how resource-poor firms survive and thrive. To remedy the deficiencies in their perspective, I then propose a dynamic theory of compositional advantage and strategy. Here, the compositional...... or all of the five basic compositional strategies. I argue there are three indispensable key success factors for a composition-based competition, i.e., aspiration (ambition-position asymmetry), attitude (being ALERT), and action (turning asymmetry into advantage). I also discuss the particular relevance...

  13. Competitive Advantage through Innovation

    Brem, Alexander; Maier, Maximilian; Wimschneider, Christine

    2016-01-01

    Purpose The purpose of this paper is to describe how Nespresso achieved competitive advantage through innovation by changing the rules of the game in its industry. Design/methodology/approach Nespresso was analyzed based on public available secondary data, in combination with related academic...... concepts on innovation and competitive advantage. Findings The company succeeded by the thorough application of a strategy that, through perfect alignment, allowed the company to reach a unique market position. However, as described in the case, it took a relatively long time and the company came close...... as a source for competitive advantage. Research limitations/implications Especially given the current market situation, the case offers different starting points for discussion about innovation and long-term company success. Practical implications Especially before the current market situation, the case...

  14. Constructing Regional advantage

    Asheim, Bjørn T.; Boschma, Ron; Cooke, Phil

    2011-01-01

    This paper presents a regional innovation policy model based on the idea of constructing regional advantage. This policy model brings together concepts like related variety, knowledge bases and policy platforms. Related variety attaches importance to knowledge spillovers across complementary...... economic development within and between regions in action lines appropriate to incorporate the basic principles behind related variety and differentiated knowledge bases....

  15. Advantages of magnification radiography

    Doi, K.

    1976-01-01

    Geometric arrangements and exposure conditions used in different magnification techniques are described and the following advantages of radiographic magnification technique are discussed: sharpness effect; noise effect; air gap effect; and visual effect. The magnification technique can be used in various diagnostic procedures as a means of improving the image quality of radiographs

  16. Mechanical Components from Highly Recoverable, Low Apparent Modulus Materials

    Padula, Santo, II (Inventor); Noebe, Ronald D. (Inventor); Stanford, Malcolm K. (Inventor); DellaCorte, Christopher (Inventor)

    2015-01-01

    A material for use as a mechanical component is formed of a superelastic intermetallic material having a low apparent modulus and a high hardness. The superelastic intermetallic material is conditioned to be dimensionally stable, devoid of any shape memory effect and have a stable superelastic response without irrecoverable deformation while exhibiting strains of at least 3%. The method of conditioning the superelastic intermetallic material is described. Another embodiment relates to lightweight materials known as ordered intermetallics that perform well in sliding wear applications using conventional liquid lubricants and are therefore suitable for resilient, high performance mechanical components such as gears and bearings.

  17. Microstructure and Mechanical Behavior of High-Entropy Alloys

    Licavoli, Joseph J.; Gao, Michael C.; Sears, John S.; Jablonski, Paul D.; Hawk, Jeffrey A.

    2015-10-01

    High-entropy alloys (HEAs) have generated interest in recent years due to their unique positioning within the alloy world. By incorporating a number of elements in high proportion, usually of equal atomic percent, they have high configurational entropy, and thus, they hold the promise of interesting and useful properties such as enhanced strength and alloy stability. The present study investigates the mechanical behavior, fracture characteristics, and microstructure of two single-phase FCC HEAs CoCrFeNi and CoCrFeNiMn with some detailed attention given to melting, homogenization, and thermo-mechanical processing. Ingots approaching 8 kg in mass were made by vacuum induction melting to avoid the extrinsic factors inherent to small-scale laboratory button samples. A computationally based homogenization heat treatment was given to both alloys in order to eliminate any solidification segregation. The alloys were then fabricated in the usual way (forging, followed by hot rolling) with typical thermo-mechanical processing parameters employed. Transmission electron microscopy was subsequently used to assess the single-phase nature of the alloys prior to mechanical testing. Tensile specimens (ASTM E8) were prepared with tensile mechanical properties obtained from room temperature through 800 °C. Material from the gage section of selected tensile specimens was extracted to document room and elevated temperature deformation within the HEAs. Fracture surfaces were also examined to note fracture failure modes. The tensile behavior and selected tensile properties were compared with results in the literature for similar alloys.

  18. Mechanical Conversion for High-Throughput TEM Sample Preparation

    Kendrick, Anthony B; Moore, Thomas M; Zaykova-Feldman, Lyudmila

    2006-01-01

    This paper presents a novel method of direct mechanical conversion from lift-out sample to TEM sample holder. The lift-out sample is prepared in the FIB using the in-situ liftout Total Release TM method. The mechanical conversion is conducted using a mechanical press and one of a variety of TEM coupons, including coupons for both top-side and back-side thinning. The press joins a probe tip point with attached TEM sample to the sample coupon and separates the complete assembly as a 3mm diameter TEM grid, compatible with commercially available TEM sample holder rods. This mechanical conversion process lends itself well to the high through-put requirements of in-line process control and to materials characterization labs where instrument utilization and sample security are critically important

  19. Thermal Mechanisms for High Amplitude Aerodynamic Flow Control (YIP 2012)

    2016-04-15

    transport aircraft , much less cruise. The search for a perfect actuator continues, but progress has been limited by the often proprietary nature these...wave generation as a mechanism for high amplitude, high bandwidth actuation has been demonstrated, but the fundamental physics of how this...moving forward with such a definition. 15. SUBJECT TERMS active flow control, energy deposition, plasma actuation 16. SECURITY CLASSIFICATION OF: 17

  20. Compositional Advantage and Strategy

    Li, Xin

    In this paper, I first critique the composition-based view of Yadong Luo and John Child for understanding how resource-poor firms survive and thrive. To remedy the deficiencies in their perspective, I then propose a dynamic theory of compositional advantage and strategy. Here, the compositional...... advantage is redefined as the attractiveness of the composition of the producer’s offering in terms of scope and perceived value/price ratio. I identify five ways or basic compositional strategies to improve the value/price ratio. A firm may have an overall compositional strategy that is composed of some...... of the present theory to understanding Chinese firms. I conclude with managerial implications and suggestions for future research....

  1. Drivers of Collaborative Advantage

    Weihe, Gudrid

    processes and behavioural dimensions is practically non-existent. This article tries to remedy the current gap in the literature by reviewing research findings on interfirm collaboration (alliances). On that basis a conceptual framework for analyzing partnership processes is developed. Finally......, the antecedents of collaborative advantage are theoretically examined, and the organizational competences contributing to collaborative success are identified. The conclusion is that operational processes and social dynamics are vital drivers of collaborative advantage. Another significant conclusion...... is that public management research can benefit from drawing upon existing alliance research. Alliance scholars have during the past couple of decades accumulated an impressive amount of knowledge on different aspects of inter-firm cooperation, and therefore the learning potential for public management scholars...

  2. Mechanism of high-temperature resistant water-base mud

    Luo, P

    1981-01-01

    Based on experiments, the causes and laws governing the changes in the performance of water-base mud under high temperature are analyzed, and the requisites and mechanism of treating agents resisting high temperature are discussed. Ways and means are sought for inhibiting, delaying and making use of the effect of high temperature on the performance of mud, while new ideas and systematic views have been expressed on the preparation of treating agents and set-up of a high temperature resistant water-base mud system. High temperature dispersion and high temperature surface inactivation of clay in the mud, as well as their effect and method of utilization are reviewed. Subjects also touched upon include degradation and cross-linking of the high-temperature resistant treating agents, their use and effect. Based on the above, the preparation of a water-base and system capable of resisting 180 to 250/sup 0/C is recommended.

  3. HDM model magnet mechanical behavior with high manganese steel collars

    Snyder, J.R.

    1994-01-01

    Westinghouse Electric Corporation (WEC) is presently under contract to the SSCL to design, develop, fabricate, and deliver superconducting dipole magnets for the High Energy Booster (HEB). As a first step toward these objectives SSCL supplied a design for short model magnets of 1.8 m in length (DSB). This design was used as a developmental tool for all phases of engineering and fabrication. Mechanical analysis of the HDM (High Energy Booster Dipole Magnets) model magnet design as specified by SSCL was performed with the following objectives: (1) to develop a thorough understanding of the design; (2) to review and verify through analytical and numerical analyses the SSCL model magnet design; (3) to identify any deficiencies that would violate design parameters specified in the HDM Design Requirements Document. A detailed analysis of the model magnet mechanical behavior was pursued by constructing a quarter section finite element model and solving with the ANSYS finite element code. Collar materials of Nitronic-40 and High-Manganese steel were both considered for the HEB model magnet program with the High-Manganese being the final selection. The primary mechanical difference in the two materials is the much lower thermal contraction of the High-Manganese steel. With this material the collars will contract less than the enclosing yoke producing an increased collar yoke interference during cooldown

  4. Mechanical design of a high field common coil magnet

    Caspi, S; Dietderich, D R; Gourlay, S A; Gupta, R; McInturff, A; Millos, G; Scanlan, R M

    1999-01-01

    A common coil design for high field 2-in-1 accelerator magnets has been previously presented as a "conductor-friendly" option for high field magnets applicable for a Very Large Hadron Collider. This paper presents the mechanical design for a 14 tesla 2-in-1 dipole based on the common coil design approach. The magnet will use a high current density Nb/sub 3/Sn conductor. The design addresses mechanical issues particular to the common coil geometry: horizontal support against coil edges, vertical preload on coil faces, end loading and support, and coil stresses and strains. The magnet is the second in a series of racetrack coil magnets that will provide experimental verification of the common coil design approach. (9 refs).

  5. High Temperature Electro-Mechanical Devices For Nuclear Applications

    Robertson, D.

    2010-01-01

    Nuclear power plants require a number of electro-mechanical devices, for example, Control Rod Drive Mechanisms (CRDM's) to control the raising and lowering of control rods and Reactor Coolant Pumps (RCP's) to circulate the primary coolant. There are potential benefits in locating electro-mechanical components in areas of the plant with high ambient temperatures. One such benefit is the reduced need to make penetrations in pressure vessels leading to simplified plant design and improved inherent safety. The feature that limits the ambient temperature at which most electrical machines may operate is the material used for the electrical insulation of the machine windings. Conventional electrical machines generally use polymer-based insulation that limits the ambient temperature they can operate in to below 200 degrees Celsius. This means that when a conventional electrical machine is required to operate in a hot area it must be actively cooled necessitating additional systems. This paper presents data gathered during investigations undertaken by Rolls-Royce into the design of high temperature electrical machines. The research was undertaken at Rolls-Royce's University Technology Centre in Advanced Electrical Machines and Drives at Sheffield University. Rolls- Royce has also been investigating high temperature wire and encapsulants and latterly techniques to provide high temperature insulation to terminations. Rolls-Royce used the experience gained from these tests to produce a high temperature electrical linear actuator at sizes representative of those used in reactor systems. This machine was tested successfully at temperatures equivalent to those found inside the reactor vessel of a pressurised water reactor through a full series of operations that replicated in service duty. The paper will conclude by discussing the impact of the findings and potential electro-mechanical designs that may utilise such high temperature technologies. (authors)

  6. High temperature mechanical performance of a hot isostatically pressed silicon nitride

    Wereszczak, A.A.; Ferber, M.K.; Jenkins, M.G.; Lin, C.K.J. [and others

    1996-01-01

    Silicon nitride ceramics are an attractive material of choice for designers and manufacturers of advanced gas turbine engine components for many reasons. These materials typically have potentially high temperatures of usefulness (up to 1400{degrees}C), are chemically inert, have a relatively low specific gravity (important for inertial effects), and are good thermal conductors (i.e., resistant to thermal shock). In order for manufacturers to take advantage of these inherent properties of silicon nitride, the high-temperature mechanical performance of the material must first be characterized. The mechanical response of silicon nitride to static, dynamic, and cyclic conditions at elevated temperatures, along with reliable and representative data, is critical information that gas turbine engine designers and manufacturers require for the confident insertion of silicon nitride components into gas turbine engines. This final report describes the high-temperature mechanical characterization and analyses that were conducted on a candidate structural silicon nitride ceramic. The high-temperature strength, static fatigue (creep rupture), and dynamic and cyclic fatigue performance were characterized. The efforts put forth were part of Work Breakdown Structure Subelement 3.2.1, {open_quotes}Rotor Data Base Generation.{close_quotes} PY6 is comparable to other hot isostatically pressed (HIPed) silicon nitrides currently being considered for advanced gas turbine engine applications.

  7. Mechanisms of Evolution in High-Consequence Drug Resistance Plasmids

    Susu He

    2016-12-01

    Full Text Available The dissemination of resistance among bacteria has been facilitated by the fact that resistance genes are usually located on a diverse and evolving set of transmissible plasmids. However, the mechanisms generating diversity and enabling adaptation within highly successful resistance plasmids have remained obscure, despite their profound clinical significance. To understand these mechanisms, we have performed a detailed analysis of the mobilome (the entire mobile genetic element content of a set of previously sequenced carbapenemase-producing Enterobacteriaceae (CPE from the National Institutes of Health Clinical Center. This analysis revealed that plasmid reorganizations occurring in the natural context of colonization of human hosts were overwhelmingly driven by genetic rearrangements carried out by replicative transposons working in concert with the process of homologous recombination. A more complete understanding of the molecular mechanisms and evolutionary forces driving rearrangements in resistance plasmids may lead to fundamentally new strategies to address the problem of antibiotic resistance.

  8. High LET radiation and mechanism of DNA damage repair

    Furusawa, Yoshiya

    2004-01-01

    Clarifying the mechanism of repair from radiation damage gives most important information on radiation effects on cells. Approximately 10% of biological experiments groups in Heavy Ion Medical Accelerator in Chiba (HIMAC) cooperative research group has performed the subject. They gave a lot of new findings on the mechanism, and solved some open questions. The reason to show the peak of relative biological effectiveness RBE at around 100-200 keV/μm causes miss-repair of DNA damage. Sub-lethal damage generated by high linear energy transfer (LET) radiation can be repaired fully. Potentially lethal damages by high-LET radiation also repaired, but the efficiency decreased with the LET, and so on. (author)

  9. Statistical mechanics of flux lines in high-temperature superconductors

    Dasgupta, C.

    1992-01-01

    The shortness of the low temperature coherence lengths of high T c materials leads to new mechanisms of pinning of flux lines. Lattice periodic modulations of the order parameters itself acts to pin vortex lines in regions of the unit cell were the order parameter is small. A presentation of flux creep and flux noise at low temperature and magnetic fields in terms of motion of simple metastable defects on flux lines is made, with a calculation of flux lattice melting. 12 refs

  10. Highly-stretchable 3D-architected Mechanical Metamaterials

    Jiang, Yanhui; Wang, Qiming

    2016-09-01

    Soft materials featuring both 3D free-form architectures and high stretchability are highly desirable for a number of engineering applications ranging from cushion modulators, soft robots to stretchable electronics; however, both the manufacturing and fundamental mechanics are largely elusive. Here, we overcome the manufacturing difficulties and report a class of mechanical metamaterials that not only features 3D free-form lattice architectures but also poses ultrahigh reversible stretchability (strain > 414%), 4 times higher than that of the existing counterparts with the similar complexity of 3D architectures. The microarchitected metamaterials, made of highly stretchable elastomers, are realized through an additive manufacturing technique, projection microstereolithography, and its postprocessing. With the fabricated metamaterials, we reveal their exotic mechanical behaviors: Under large-strain tension, their moduli follow a linear scaling relationship with their densities regardless of architecture types, in sharp contrast to the architecture-dependent modulus power-law of the existing engineering materials; under large-strain compression, they present tunable negative-stiffness that enables ultrahigh energy absorption efficiencies. To harness their extraordinary stretchability and microstructures, we demonstrate that the metamaterials open a number of application avenues in lightweight and flexible structure connectors, ultraefficient dampers, 3D meshed rehabilitation structures and stretchable electronics with designed 3D anisotropic conductivity.

  11. Mechanical properties of LMR structural materials at high temperature

    Kim, D. W.; Kuk, I. H.; Ryu, W. S. and others

    1999-03-01

    Austenitic stainless is used for the structural material of liquid metal reactor (LMR) because of good mechanical properties at high temperature. Stainless steel having more resistant to temperature by adding minor element has been developing for operating the LMR at higher temperature. Of many elements, nitrogen is a prospective element to modify type 316L(N) stainless steel because nitrogen is the most effective element for solid solution and because nitrogen retards the precipitation of carbide at grain boundary. Ti, Nb, and V are added to improve creep properties by stabilizing the carbides through forming MC carbide. Testing techniques of tensile, fatigue, creep, and creep-fatigue at high temperature are difficult. Moreover, testing times for creep and creep-fatigue tests are very long up to several tens of thousands hours because creep and creep-fatigue phenomena are time-dependent damage mechanism. So, it is hard to acquire the material data for designing LMR systems during a limited time. In addition, the integrity of LMR structural materials at the end of LMR life has to be predicted from the laboratory data tested during the short term because there is no data tested during 40 years. Therefore, the effect of elements on mechanical properties at high temperature was reviewed in this study and many methods to predict the long-term behaviors of structural materials by simulated modelling equation is shown in this report. (author). 32 refs., 9 tabs., 38 figs

  12. The Mechanical Design Optimization of a High Field HTS Solenoid

    Lalitha, SL; Gupta, RC

    2015-06-01

    This paper describes the conceptual design optimization of a large aperture, high field (24 T at 4 K) solenoid for a 1.7 MJ superconducting magnetic energy storage device. The magnet is designed to be built entirely of second generation (2G) high temperature superconductor tape with excellent electrical and mechanical properties at the cryogenic temperatures. The critical parameters that govern the magnet performance are examined in detail through a multiphysics approach using ANSYS software. The analysis results formed the basis for the performance specification as well as the construction of the magnet.

  13. RECONSIDERING COMPETITIVE ADVANTAGES

    Valentina Zaharia

    2011-12-01

    Full Text Available Development of the competitive advantage involves a considerable effort from any organization. In particular, those organizations involved in a strong competitive market require the development of strategies to allocate long-term strategic marketing resources, efficiently and with easily quantifiable results. Faced with a multitude of phenomena and processes sometimes contradictory on different markets of consumption, contemporarily marketing has the mission to develop as creative as possible the business strategy of the organizations, their capacity of interacting with customers and other categories of audience. Such concepts as strategic positioning, relational marketing, management of the relationship with the consumer, marketing integrated research, a.s.o. are only a few of the tools with the help of which the marketing managers will implement successful operational strategies. All these developments are creating a real new paradigm of Marketing aimed to better explain the new types of complex market relationship in which the 21st Century organization is .

  14. Canadian competitive advantage

    Wills, J.

    1997-01-01

    The evolution of the Canadian petrochemical industry was outlined, emphasizing the proximity to feedstocks as the principal advantage enjoyed by the industry over its international competitors. Annual sales statistics for 1995 were provided. Key players in the Canadian petrochemical industry (Nova, Dow, DuPont, Methanex, Esso, Union Carbide, Shell and Celanese), their share of the market and key products were noted. Manufacturing facilities are located primarily in Alberta, southern Ontario and Quebec. The feedstock supply infrastructure, historical and alternative ethane pricing in Canada and the US, the North American market for petrochemicals, the competitiveness of the industry, tax competitiveness among Canadian provinces and the US, the Canada - US unit labour cost ratio, ethylene facility construction costs in Canada relative to the US Gulf Coast, and projected 1997 financial requirements were reviewed. 19 figs

  15. A high throughput mechanical screening device for cartilage tissue engineering.

    Mohanraj, Bhavana; Hou, Chieh; Meloni, Gregory R; Cosgrove, Brian D; Dodge, George R; Mauck, Robert L

    2014-06-27

    Articular cartilage enables efficient and near-frictionless load transmission, but suffers from poor inherent healing capacity. As such, cartilage tissue engineering strategies have focused on mimicking both compositional and mechanical properties of native tissue in order to provide effective repair materials for the treatment of damaged or degenerated joint surfaces. However, given the large number design parameters available (e.g. cell sources, scaffold designs, and growth factors), it is difficult to conduct combinatorial experiments of engineered cartilage. This is particularly exacerbated when mechanical properties are a primary outcome, given the long time required for testing of individual samples. High throughput screening is utilized widely in the pharmaceutical industry to rapidly and cost-effectively assess the effects of thousands of compounds for therapeutic discovery. Here we adapted this approach to develop a high throughput mechanical screening (HTMS) system capable of measuring the mechanical properties of up to 48 materials simultaneously. The HTMS device was validated by testing various biomaterials and engineered cartilage constructs and by comparing the HTMS results to those derived from conventional single sample compression tests. Further evaluation showed that the HTMS system was capable of distinguishing and identifying 'hits', or factors that influence the degree of tissue maturation. Future iterations of this device will focus on reducing data variability, increasing force sensitivity and range, as well as scaling-up to even larger (96-well) formats. This HTMS device provides a novel tool for cartilage tissue engineering, freeing experimental design from the limitations of mechanical testing throughput. © 2013 Published by Elsevier Ltd.

  16. High-Mn steel weldment mechanical properties at 4 K

    Chan, J.W.; Sunwoo, A.J.; Morris, J.W. Jr.

    1988-06-01

    Advanced high-field superconducting magnets of the next generation of magnetic confinement fusion devices will require structural alloys with high yield strength and high toughness at cryogenic temperatures. Commercially available alloys used in the current generation of magnets, such as 300 series stainless steels, do not have the required properties. N-strengthened, high-Mn alloys meet base plate requirements in the as-rolled condition. However, the property changes associated with weld microstructural and chemical changes in these alloys have not been well characterized. In this work welding induced cryogenic mechanical property changes of an 18Mn-16Cr-5Ni-0.2N alloy are correlated with as-solidified weld microstructures and chemistries. 30 refs., 12 figs., 3 tabs

  17. High strength-high conductivity Cu-Fe composites produced by powder compaction/mechanical reduction

    Verhoeven, J.D.; Spitzig, W.A.; Gibson, E.D.; Anderson, I.E.

    1991-08-27

    A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an ''in-situ'' Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite. 5 figures.

  18. High strength-high conductivity Cu--Fe composites produced by powder compaction/mechanical reduction

    Verhoeven, John D.; Spitzig, William A.; Gibson, Edwin D.; Anderson, Iver E.

    1991-08-27

    A particulate mixture of Cu and Fe is compacted and mechanically reduced to form an "in-situ" Cu-Fe composite having high strength and high conductivity. Compaction and mechanical reduction of the particulate mixture are carried out at a temperature and time at temperature selected to avoid dissolution of Fe into the Cu matrix particulates to a harmful extent that substantially degrades the conductivity of the Cu-Fe composite.

  19. A Conceptual Mapping Resource Advantage Theory, Competitive Advantage Theory, and Transient Competitive Advantage

    Jasanta PERANGINANGIN

    2015-01-01

    Competitive advantage is the main purposed of the business entity focusing on market base view. Resource advantage theorists put their concern to empowering resources development with resources based view, in the other side needs to redefining competitive advantage. All the competitive advantage are transient, concluded the end of competitive advantage. Redefining competitive advantage by selling migration and shrewdness outward. This research to emphasize innovation capability rarely appears...

  20. High-speed 3D surface measurement with mechanical projector

    Hyun, Jae-Sang; Zhang, Song

    2017-05-01

    This paper presents a method to overcome the light spectral range limitation of using digital-light-processing (DLP) projector for 3D shape measurement by developing a mechanical projector. The mechanical projector enables much broader spectral range of light than that the DLP projector allows. The rapidly spinning disk with binary structures can generate desired sinusoidal patterns at a frequency of 10 kHz or higher with a single DC motor. By precisely synchronizing the camera with the projector, phase-shifted fringe patterns can be accurately captured for high-accuracy 3D shape measurement. We further employed a computational framework that could enable absolute phase and thus absolute 3D shape measurement. We developed such prototype system that experimentally demonstrated the success of the proposed method.

  1. Mechanical properties of highly textured Cu/Ni multilayers

    Liu, Y.; Bufford, D.; Wang, H.; Sun, C.; Zhang, X.

    2011-01-01

    We report on the synthesis of highly (1 1 1) and (1 0 0) textured Cu/Ni multilayers with individual layer thicknesses, h, varying from 1 to 200 nm. When, h, decreases to 5 nm or less, X-ray diffraction spectra show epitaxial growth of Cu/Ni multilayers. High resolution transmission electron microscopy studies show the coexistence of nanotwins and coherent layer interfaces in highly (1 1 1) textured Cu/Ni multilayers with smaller h. Hardnesses of multilayer films increase with decreasing h, approach a maximum at h of a few nanometers, and show softening thereafter at smaller h. The influence of layer interfaces as well as twin interfaces on strengthening mechanisms of multilayers and the formation of twins in Ni in multilayers are discussed.

  2. Mechanically recovered poultry meat sausages manufactured with high hydrostatic pressure.

    Yuste, J; Mor-Mur, M; Capellas, M; Guamis, B; Pla, R

    1999-06-01

    The effect of high pressure processing at high temperature on texture and color of frankfurter-type sausages made with different contents of mechanically recovered poultry meat (MRPM) was evaluated and compared with that of a standard cooking process. Five types of sausages containing 100, 75, 50, 25, and 0% MRPM and 0, 25, 50, 75, and 100% of minced pork meat (MPM), respectively, were manufactured. They were pressurized at 500 MPa for 30 min at 50, 60, 70, and 75 C or cooked at 75 C for 30 min. Pressure-treated sausages were less springy and firm, but more cohesive. Moreover, color of pressurized sausages was lighter and more yellow than that of conventionally cooked sausages. Addition of MPM increased cohesiveness, hardness, and force at 80% compression. Minced pork meat also caused the appearance of sausages to be lighter, less red, and less yellow. Cooked sausages made with MRPM can have an attractive appearance and texture via high pressure processing.

  3. Mechanisms of Evolution in High-Consequence Drug Resistance Plasmids.

    He, Susu; Chandler, Michael; Varani, Alessandro M; Hickman, Alison B; Dekker, John P; Dyda, Fred

    2016-12-06

    The dissemination of resistance among bacteria has been facilitated by the fact that resistance genes are usually located on a diverse and evolving set of transmissible plasmids. However, the mechanisms generating diversity and enabling adaptation within highly successful resistance plasmids have remained obscure, despite their profound clinical significance. To understand these mechanisms, we have performed a detailed analysis of the mobilome (the entire mobile genetic element content) of a set of previously sequenced carbapenemase-producing Enterobacteriaceae (CPE) from the National Institutes of Health Clinical Center. This analysis revealed that plasmid reorganizations occurring in the natural context of colonization of human hosts were overwhelmingly driven by genetic rearrangements carried out by replicative transposons working in concert with the process of homologous recombination. A more complete understanding of the molecular mechanisms and evolutionary forces driving rearrangements in resistance plasmids may lead to fundamentally new strategies to address the problem of antibiotic resistance. The spread of antibiotic resistance among Gram-negative bacteria is a serious public health threat, as it can critically limit the types of drugs that can be used to treat infected patients. In particular, carbapenem-resistant members of the Enterobacteriaceae family are responsible for a significant and growing burden of morbidity and mortality. Here, we report on the mechanisms underlying the evolution of several plasmids carried by previously sequenced clinical Enterobacteriaceae isolates from the National Institutes of Health Clinical Center (NIH CC). Our ability to track genetic rearrangements that occurred within resistance plasmids was dependent on accurate annotation of the mobile genetic elements within the plasmids, which was greatly aided by access to long-read DNA sequencing data and knowledge of their mechanisms. Mobile genetic elements such as

  4. Improvement in mechanical properties of high concentration particle doped thermoset composites

    Ahmed, N.

    2009-01-01

    The paper relates to high concentration particle doped composites based on thermosetting polymer systems in which the sequential addition of particles of certain size distribution is followed by curing and casting of the slurry to form a thermoset composite. Conventionally, at a threshold of beyond 90% of particles by weight of the polymer using triglyceride, the mechanical properties of the composite exhibit a sharp decline. The present research mitigates this behavior by incorporating a unique combination of cross-linking agents in the base polymer to impart exceptional mechanical properties to the composite. More specifically, the base polymer consists of butadiene, with triglyceride as cross-linking agent together with hydroxy-alkane as the chain extension precursors, when tune to the appropriate level of hard segment ratio in the polymer. An added advantage according to the present work resides in the analytical nature of butadiene pre-polymer as opposed to natural product; traditional composites based on natural sources are hampered by their inconsistent chemical composition and poor shelf life in the fabricated composite. The thermoset composite according the present research exhibits superior tensile strength (200-300 psi) properties using particle loading as high as 92% by weight of the fabricated composite as measured on a Tinius Olsen machine. Dynamic Mechanical Testing reveals interesting combination of storage and loss moduli in the fabricated specimens as a function of optimizing the thermal response of the viscoelastic composite to imposed vibration loading. (author)

  5. Shock loading influence on mechanical behavior of high purity iron

    Buy, Francois; Voltz, Christophe

    2004-01-01

    This paper proposes the analysis of shock wave effects for high purity iron. The method developed is based on the characterization of the mechanical behavior of as received and shocked material. Shock effect is generated through plate impact tests performed in the range of 4 GPa to 39 GPa on a single stage light gas gun or a powder gun. Therefore, as-received and impacted materials are characterized. A formalism proposed by J.R.Klepaczko and based on physical relations has been adopted to describe stress strain curves

  6. Teaching fluid mechanics to high schoolers: methods, challenges, and outcome

    Manikantan, Harishankar

    2017-11-01

    This talk will summarize the goals, methods, and both short- and long-term feedback from two high-school-level courses in fluid mechanics involving 43 students and cumulatively spanning over 100 hours of instruction. The goals of these courses were twofold: (a) to spark an interest in science and engineering and attract a more diverse demographic into college-level STEM programs; and (b) to train students in a `college-like' method of approaching the physics of common phenomena, with fluid mechanics as the context. The methods of instruction included classes revolving around the idea of dispelling misconceptions, group activities, `challenge' rounds and mock design projects to use fluid mechanics phenomena to achieve a specified goal, and simple hands-on experiments. The feedback during instruction was overwhelmingly positive, particularly in terms of a changing and favorable attitude towards math and engineering. Long after the program, a visible impact lies in a diverse group of students acknowledging that the course had a positive effect in their decision to choose an engineering or science major in a four-year college.

  7. Electrical and mechanical properties of highly elongated high density polyethylene as cryogenic insulation materials

    Yoshino, Katsumi; Park, Dae-Hee; Miyata, Kiyomi; Yamaoka, Hitoshi; Itoh, Minoru; Ichihara, Syouji.

    1989-01-01

    Electrical and mechanical properties of highly elongated high density polyethylene were investigated in the temperature range between 4.2 K and 400 K from a viewpoint of electrical insulation at low temperature and the following properties have been clarified. (1) The electrical conductivity of samples decreases with increasing draw ratio, and also decreases at cryogenic temperature. (2) Breakdown strength of highly elongated sample is similar to that of non-elongated sample. It is nearby temperature independent below 300 K but at higher temperature it falls steeply. (3) Mechanical breakdown stress and elastic modulus of high density polyethylene increase with increasing draw ratio. Their values at liquid nitrogen temperature are much higher than that at room temperature. On the other hand, strains decreases at liquid nitrogen temperature. (4) Break of the sample develops in the direction of 45deg from the direction of stress both at room temperature and at cryogenic temperature. (5) The characteristic of mechanical breakdown at liquid nitrogen temperature can be explained by a brittleness fracture process. (6) Toughness of high density polyethylene increases with increasing draw ratio until draw ratio of 5, and it decreased, and increase at higher draw ratio. However at extremely high draw ratio of 10 it again increases. These findings clearly indicate that highly elongated high density polyethylene has good electrical and mechanical properties at cryogenic temperature and can be used as the insulating materials at cryogenic temperature. (author)

  8. Mechanics

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  9. Mechanisms and factors that influence high frequency retroviral recombination

    Delviks-Frankenberry, Krista; Galli, Andrea; Nikolaitchik, Olga

    2011-01-01

    With constantly changing environmental selection pressures, retroviruses rely upon recombination to reassort polymorphisms in their genomes and increase genetic diversity, which improves the chances for the survival of their population. Recombination occurs during DNA synthesis, whereby reverse...... transcriptase undergoes template switching events between the two copackaged RNAs, resulting in a viral recombinant with portions of the genetic information from each parental RNA. This review summarizes our current understanding of the factors and mechanisms influencing retroviral recombination, fidelity...... of the recombination process, and evaluates the subsequent viral diversity and fitness of the progeny recombinant. Specifically, the high mutation rates and high recombination frequencies of HIV-1 will be analyzed for their roles in influencing HIV-1 global diversity, as well as HIV-1 diagnosis, drug treatment...

  10. Mechanisms and Factors that Influence High Frequency Retroviral Recombination

    Delviks-Frankenberry, Krista; Galli, Andrea; Nikolaitchik, Olga; Mens, Helene; Pathak, Vinay K.; Hu, Wei-Shau

    2011-01-01

    With constantly changing environmental selection pressures, retroviruses rely upon recombination to reassort polymorphisms in their genomes and increase genetic diversity, which improves the chances for the survival of their population. Recombination occurs during DNA synthesis, whereby reverse transcriptase undergoes template switching events between the two copackaged RNAs, resulting in a viral recombinant with portions of the genetic information from each parental RNA. This review summarizes our current understanding of the factors and mechanisms influencing retroviral recombination, fidelity of the recombination process, and evaluates the subsequent viral diversity and fitness of the progeny recombinant. Specifically, the high mutation rates and high recombination frequencies of HIV-1 will be analyzed for their roles in influencing HIV-1 global diversity, as well as HIV-1 diagnosis, drug treatment, and vaccine development. PMID:21994801

  11. High Doses Gamma Radiolysis of PVC: Mechanisms of Degradation

    Colombani, J.

    2006-01-01

    PVC radiolysis leads to the formation of various degradation products: radicals, gas, oxidized products or polyenes. In order to predict the formation of the degradation products with regard to irradiation and ageing parameters, it is important to improve the understanding of the radiolysis mechanisms of PVC. Thus, we used several analytical techniques (Electron Spin Resonance, Fourier Transform Infrared spectroscopy, Nuclear Magnetic Resonance, Size Exclusion Chromatography) to get information on PVC samples irradiated at high doses (up to 4MGy) under different conditions. Gamma irradiation induces the formation of various radicals into PVC. Older studies were generally focused on the effect of low dose and/or low temperature irradiations on PVC. We present here ESR signals of PVC irradiated at high doses and at room temperature. We show that peroxyl radicals are producted by radiolysis under aerobe conditions and that polyenyl radicals are formed under anaerobe conditions. PVC radiolysis induces gas production and especially hydrogen chloride. Production of hydrogen chloride is well known until 1 MGy. We have studied by FTIR, the evolution of the quantity of HCl produced until 4 MGy. We show that higher irradiation dose leads to the lower radiolytic yield of HCl (G(HCl)). Moreover, G(HCl) obtained in aerobe conditions is about fourfold as great as G(HCl) observed in anaerobe radiolysis. Propagation and termination reactions induce degradation products: polyene sequences and crosslinking reactions are observed under anaerobe conditions; oxidized products with addition of chain scissions are formed under aerobe conditions. Although the literature about PVC radiolysis is rich, the main reacting pathways are not well established. Moreover the high doses studies are almost non-existent. We show by FTIR that aerobe radiolysis induces formation of ketons and acids. NMR experiments confirme these results but also focuse on small acids formed (with 2, 3 or 4 carbons). The

  12. High-resolution remotely sensed small target detection by imitating fly visual perception mechanism.

    Huang, Fengchen; Xu, Lizhong; Li, Min; Tang, Min

    2012-01-01

    The difficulty and limitation of small target detection methods for high-resolution remote sensing data have been a recent research hot spot. Inspired by the information capture and processing theory of fly visual system, this paper endeavors to construct a characterized model of information perception and make use of the advantages of fast and accurate small target detection under complex varied nature environment. The proposed model forms a theoretical basis of small target detection for high-resolution remote sensing data. After the comparison of prevailing simulation mechanism behind fly visual systems, we propose a fly-imitated visual system method of information processing for high-resolution remote sensing data. A small target detector and corresponding detection algorithm are designed by simulating the mechanism of information acquisition, compression, and fusion of fly visual system and the function of pool cell and the character of nonlinear self-adaption. Experiments verify the feasibility and rationality of the proposed small target detection model and fly-imitated visual perception method.

  13. High-Resolution Remotely Sensed Small Target Detection by Imitating Fly Visual Perception Mechanism

    Fengchen Huang

    2012-01-01

    Full Text Available The difficulty and limitation of small target detection methods for high-resolution remote sensing data have been a recent research hot spot. Inspired by the information capture and processing theory of fly visual system, this paper endeavors to construct a characterized model of information perception and make use of the advantages of fast and accurate small target detection under complex varied nature environment. The proposed model forms a theoretical basis of small target detection for high-resolution remote sensing data. After the comparison of prevailing simulation mechanism behind fly visual systems, we propose a fly-imitated visual system method of information processing for high-resolution remote sensing data. A small target detector and corresponding detection algorithm are designed by simulating the mechanism of information acquisition, compression, and fusion of fly visual system and the function of pool cell and the character of nonlinear self-adaption. Experiments verify the feasibility and rationality of the proposed small target detection model and fly-imitated visual perception method.

  14. High-mechanical-strength single-pulse draw tower gratings

    Rothhardt, Manfred W.; Chojetzki, Christoph; Mueller, Hans Rainer

    2004-11-01

    The inscription of fiber Bragg gratings during the drawing process is a very useful method to realize sensor arrays with high numbers of gratings and excellent mechanical strength and also type II gratings with high temperature stability. Results of single pulse grating arrays with numbers up to 100 and definite wavelengths and positions for sensor applications were achieved at 1550 nm and 830 nm using new photosensitive fibers developed in IPHT. Single pulse type I gratings at 1550 nm with more than 30% reflectivity were shown first time to our knowledge. The mechanical strength of this fiber with an Ormocer coating with those single pulse gratings is the same like standard telecom fibers. Weibull plots of fiber tests will be shown. At 830 nm we reached more than 10% reflectivity with single pulse writing during the fiber drawing in photosensitive fibers with less than 16 dB/km transmission loss. These gratings are useful for stress and vibration sensing applications. Type II gratings with reflectivity near 100% and smooth spectral shape and spectral width of about 1 nm are temperature stable up to 1200 K for short time. They are also realized in the fiber drawing process. These gratings are useful for temperature sensor applications.

  15. Possible antipolar pairing mechanism in high-temperature superconductors

    Cardwell, D.A.; Shorrocks, N.M.

    1989-01-01

    An antipolar pairing mechanism for free charge carriers in high-T c superconducting compounds is proposed qualitatively. This involves the establishment of a two-dimensional (2D) array of effective charge-coupling centers within the superconducting lattice via a specific phonon distortion of cation species along a nonmajor crystallographic direction. A fundamental requirement of this model is that the density of such coupling centers decreases with decreasing temperature. In the case of Y-Ba-Cu-O, it is asserted that charge carriers in a 2D oxygen band adjacent to the phonon-containing plane become localized by the resulting (local) field distortion. Cooper pairs may then form when the charge-coupling-center density falls below the charge-carrier density. Such a mechanism could be mediated by a longitudinal phonon which softens at low temperatures to produce an antipolar state, such as that incipient to an antiferroelectric distortion of the lattice (i.e., in the zero-frequency limiting case). This model, which may be investigated experimentally by low-temperature Raman spectroscopy, isotopic substitution, and x-ray diffractometry at 4.2 K, can be applied to all p-type high-T c systems. In addition, it may account for the observed lattice anisotropy and short coherence length characteristic of these materials

  16. Selection mechanisms underlying high impact biomedical research--a qualitative analysis and causal model.

    Hilary Zelko

    Full Text Available BACKGROUND: Although scientific innovation has been a long-standing topic of interest for historians, philosophers and cognitive scientists, few studies in biomedical research have examined from researchers' perspectives how high impact publications are developed and why they are consistently produced by a small group of researchers. Our objective was therefore to interview a group of researchers with a track record of high impact publications to explore what mechanism they believe contribute to the generation of high impact publications. METHODOLOGY/PRINCIPAL FINDINGS: Researchers were located in universities all over the globe and interviews were conducted by phone. All interviews were transcribed using standard qualitative methods. A Grounded Theory approach was used to code each transcript, later aggregating concept and categories into overarching explanation model. The model was then translated into a System Dynamics mathematical model to represent its structure and behavior. Five emerging themes were found in our study. First, researchers used heuristics or rules of thumb that came naturally to them. Second, these heuristics were reinforced by positive feedback from their peers and mentors. Third, good communication skills allowed researchers to provide feedback to their peers, thus closing a positive feedback loop. Fourth, researchers exhibited a number of psychological attributes such as curiosity or open-mindedness that constantly motivated them, even when faced with discouraging situations. Fifth, the system is dominated by randomness and serendipity and is far from a linear and predictable environment. Some researchers, however, took advantage of this randomness by incorporating mechanisms that would allow them to benefit from random findings. The aggregation of these themes into a policy model represented the overall expected behavior of publications and their impact achieved by high impact researchers. CONCLUSIONS: The proposed

  17. Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices

    Gamzina, Diana

    Diana Gamzina March 2016 Mechanical and Aerospace Engineering Multiscale Thermo-Mechanical Design and Analysis of High Frequency and High Power Vacuum Electron Devices Abstract A methodology for performing thermo-mechanical design and analysis of high frequency and high average power vacuum electron devices is presented. This methodology results in a "first-pass" engineering design directly ready for manufacturing. The methodology includes establishment of thermal and mechanical boundary conditions, evaluation of convective film heat transfer coefficients, identification of material options, evaluation of temperature and stress field distributions, assessment of microscale effects on the stress state of the material, and fatigue analysis. The feature size of vacuum electron devices operating in the high frequency regime of 100 GHz to 1 THz is comparable to the microstructure of the materials employed for their fabrication. As a result, the thermo-mechanical performance of a device is affected by the local material microstructure. Such multiscale effects on the stress state are considered in the range of scales from about 10 microns up to a few millimeters. The design and analysis methodology is demonstrated on three separate microwave devices: a 95 GHz 10 kW cw sheet beam klystron, a 263 GHz 50 W long pulse wide-bandwidth sheet beam travelling wave tube, and a 346 GHz 1 W cw backward wave oscillator.

  18. Visual quality analysis of femtosecond LASIK and iris location guided mechanical SBK for high myopia

    Hong-Su Jiang

    2015-07-01

    Full Text Available AIM: To make a analysis of visual quality of iris location guided femtosecond laser assisted in situ keratomi(LASIKand iris location guided mechanical sub-bowman keratomileusis(SBKfor high myopia treatment. METHODS:Femtosecond LASIK(study groupwas performed in 102 eyes of 51 patients with high myopia and 70 eyes of 35 patients were received mechanical SBK(control groupfrom January to October 2013. The spherical refraction of all the patients was from -6.00~-9.50D. Best corrected visual acuity(BCVAof the patients was ≥1.0. Uncorrected visual acuity(UCVA, BCVA, thickness of cornea flap, contrast sensitivity function(CSFand senior ocular aberration were examined in these patients and follow-up was 1a. RESULTS: At 1a after surgery 94.1% UCVA in study group reached ≥1.0 and there was 94.3% in control group. There was no significant difference between two groups(P>0.05. Residual refraction of study group was -0.08±0.10 D and control group was -0.10±0.07 D. There was no significant difference of residual refraction between two groups(P>0.05. C12, C8 of senior ocular aberration and RMSH in study group was less than control group, amplification: 0.1642±0.0519 and 0.2229±0.0382(t=8.077, Pt=0.556, P>0.05. C8 was 0.0950±0.069 and 0.1858±0.095(t=7.261, Pt=12.801, PP>0.05.CONCLUSION: Femtosecond LASIK and mechanical SBK is effective for high myopia. Compared to mechanical SBK, femtosecond LASIK shows more advantages in the senior ocular aberration and visual quality. The cornea flap is more regular from central to peripheral area with femtosecond laser.

  19. High Precision Edge Detection Algorithm for Mechanical Parts

    Duan Zhenyun

    2018-04-01

    Full Text Available High precision and high efficiency measurement is becoming an imperative requirement for a lot of mechanical parts. So in this study, a subpixel-level edge detection algorithm based on the Gaussian integral model is proposed. For this purpose, the step edge normal section line Gaussian integral model of the backlight image is constructed, combined with the point spread function and the single step model. Then gray value of discrete points on the normal section line of pixel edge is calculated by surface interpolation, and the coordinate as well as gray information affected by noise is fitted in accordance with the Gaussian integral model. Therefore, a precise location of a subpixel edge was determined by searching the mean point. Finally, a gear tooth was measured by M&M3525 gear measurement center to verify the proposed algorithm. The theoretical analysis and experimental results show that the local edge fluctuation is reduced effectively by the proposed method in comparison with the existing subpixel edge detection algorithms. The subpixel edge location accuracy and computation speed are improved. And the maximum error of gear tooth profile total deviation is 1.9 μm compared with measurement result with gear measurement center. It indicates that the method has high reliability to meet the requirement of high precision measurement.

  20. High Precision Edge Detection Algorithm for Mechanical Parts

    Duan, Zhenyun; Wang, Ning; Fu, Jingshun; Zhao, Wenhui; Duan, Boqiang; Zhao, Jungui

    2018-04-01

    High precision and high efficiency measurement is becoming an imperative requirement for a lot of mechanical parts. So in this study, a subpixel-level edge detection algorithm based on the Gaussian integral model is proposed. For this purpose, the step edge normal section line Gaussian integral model of the backlight image is constructed, combined with the point spread function and the single step model. Then gray value of discrete points on the normal section line of pixel edge is calculated by surface interpolation, and the coordinate as well as gray information affected by noise is fitted in accordance with the Gaussian integral model. Therefore, a precise location of a subpixel edge was determined by searching the mean point. Finally, a gear tooth was measured by M&M3525 gear measurement center to verify the proposed algorithm. The theoretical analysis and experimental results show that the local edge fluctuation is reduced effectively by the proposed method in comparison with the existing subpixel edge detection algorithms. The subpixel edge location accuracy and computation speed are improved. And the maximum error of gear tooth profile total deviation is 1.9 μm compared with measurement result with gear measurement center. It indicates that the method has high reliability to meet the requirement of high precision measurement.

  1. Setting Mechanical Properties of High Strength Steels for Rapid Hot Forming Processes

    Löbbe, Christian; Hering, Oliver; Hiegemann, Lars; Tekkaya, A. Erman

    2016-01-01

    Hot stamping of sheet metal is an established method for the manufacturing of light weight products with tailored properties. However, the generally-applied continuous roller furnace manifests two crucial disadvantages: the overall process time is long and a local setting of mechanical properties is only feasible through special cooling techniques. Hot forming with rapid heating directly before shaping is a new approach, which not only reduces the thermal intervention in the zones of critical formability and requested properties, but also allows the processing of an advantageous microstructure characterized by less grain growth, additional fractions (e.g., retained austenite), and undissolved carbides. Since the austenitization and homogenization process is strongly dependent on the microstructure constitution, the general applicability for the process relevant parameters is unknown. Thus, different austenitization parameters are analyzed for the conventional high strength steels 22MnB5, Docol 1400M, and DP1000 in respect of the mechanical properties. In order to characterize the resulting microstructure, the light optical and scanning electron microscopy, micro and macro hardness measurements, and the X-ray diffraction are conducted subsequent to tensile tests. The investigation proves not only the feasibility to adjust the strength and ductility flexibly, unique microstructures are also observed and the governing mechanisms are clarified. PMID:28773354

  2. The Advantage of Discordance

    Dalton, Leslie W.; Gerds, Thomas A.

    2017-01-01

    Discordance among multiple assessments has been a reason to criticize a biomarker. But, if different assessments are all relevant, the meaning of discordance requires explanation. As an example, for 1085 breast cancers, a low (score 1), intermediate (score 2) or high nuclear grade (NG) (score 3) ...

  3. High mechanical Q-factor measurements on silicon bulk samples

    Nawrodt, R; Zimmer, A; Koettig, T; Schwarz, C; Heinert, D; Hudl, M; Neubert, R; Thuerk, M; Nietzsche, S; Vodel, W; Seidel, P [Friedrich-Schiller-Universitaet, Institut fuer Festkoerperphysik, Helmholtzweg 5, D-07743 Jena (Germany); Tuennermann, A [Friedrich-Schiller-Universitaet, Institut fuer Angewandte Physik, Max-Wien-Platz 1, D-07743 Jena (Germany)], E-mail: ronny.nawrodt@uni-jena.de

    2008-07-15

    Future gravitational wave detectors will be limited by different kinds of noise. Thermal noise from the coatings and the substrate material will be a serious noise contribution within the detection band of these detectors. Cooling and the use of a high mechanical Q-factor material as a substrate material will reduce the thermal noise contribution from the substrates. Silicon is one of the most interesting materials for a third generation cryogenic detector. Due to the fact that the coefficient of thermal expansion vanishes at 18 and 125 K the thermoelastic contribution to the thermal noise will disappear. We present a systematic analysis of the mechanical Q-factor at low temperatures between 5 and 300 K on bulk silicon (100) samples which are boron doped. The thickness of the cylindrical samples is varied between 6, 12, 24, and 75mm with a constant diameter of 3 inches. For the 75mm substrate a comparison between the (100) and the (111) orientation is presented. In order to obtain the mechanical Q-factor a ring-down measurement is performed. Thus, the substrate is excited to resonant vibrations by means of an electrostatic driving plate and the subsequent ring-down is recorded using a Michelson-like interferometer. The substrate itself is suspended as a pendulum by means of a tungsten wire loop. All measurements are carried out in a special cryostat which provides a temperature stability of better than 0.1K between 5 and 300K during the experiment. The influence of the suspension on the measurements is experimentally investigated and discussed. At 5.8K a highest Q-factor of 4.5 x 10{sup 8} was achieved for the 14.9 kHz mode of a silicon (100) substrate with a diameter of 3 inches and a thickness of 12 mm.

  4. Defense High-Level Waste Leaching Mechanisms Program. Final report

    Mendel, J.E.

    1984-08-01

    The Defense High-Level Waste Leaching Mechanisms Program brought six major US laboratories together for three years of cooperative research. The participants reached a consensus that solubility of the leached glass species, particularly solubility in the altered surface layer, is the dominant factor controlling the leaching behavior of defense waste glass in a system in which the flow of leachant is constrained, as it will be in a deep geologic repository. Also, once the surface of waste glass is contacted by ground water, the kinetics of establishing solubility control are relatively rapid. The concentrations of leached species reach saturation, or steady-state concentrations, within a few months to a year at 70 to 90 0 C. Thus, reaction kinetics, which were the main subject of earlier leaching mechanisms studies, are now shown to assume much less importance. The dominance of solubility means that the leach rate is, in fact, directly proportional to ground water flow rate. Doubling the flow rate doubles the effective leach rate. This relationship is expected to obtain in most, if not all, repository situations

  5. Wear mechanisms in powder metallurgy high speed steels matrix composites

    Gordo, E.; Martinez, M. A.; Torralba, J. M.; Jimenez, J. A.

    2001-01-01

    The development of metal matrix composites has a major interest for automotive and cutting tools industries since they possess better mechanical properties and wear resistance than corresponding base materials. One of the manufacturing methods for these materials includes processing by powder metallurgy techniques. in this case, blending of both, base material and reinforcement powders constitute the most important process in order to achieve a homogeneous distribution of second phase particles. in the present work, composite materials of M3/2 tool steel reinforced with 2.5,5 and 8 vol% of niobium carbide have been prepared. In order to ensure a homogeneous mix, powders of both materials were mixed by dry high-energy mechanical milling at 200 r.p.m. for 40 h. After a recovering annealing, two routes for consolidate were followed die pressing and vacuum sintering, and hot isostatic pressing (HIP). Pin-on-disc tests were carried out to evaluate wear behaviour in all the materials. Results show that ceramic particles additions improve wear resistance of base material. (Author) 9 refs

  6. High Temperature Deformation Mechanisms in a DLD Nickel Superalloy

    Sean Davies

    2017-04-01

    Full Text Available The realisation of employing Additive Layer Manufacturing (ALM technologies to produce components in the aerospace industry is significantly increasing. This can be attributed to their ability to offer the near-net shape fabrication of fully dense components with a high potential for geometrical optimisation, all of which contribute to subsequent reductions in material wastage and component weight. However, the influence of this manufacturing route on the properties of aerospace alloys must first be fully understood before being actively applied in-service. Specimens from the nickel superalloy C263 have been manufactured using Powder Bed Direct Laser Deposition (PB-DLD, each with unique post-processing conditions. These variables include two build orientations, vertical and horizontal, and two different heat treatments. The effects of build orientation and post-process heat treatments on the materials’ mechanical properties have been assessed with the Small Punch Tensile (SPT test technique, a practical test method given the limited availability of PB-DLD consolidated material. SPT testing was also conducted on a cast C263 variant to compare with PB-DLD derivatives. At both room and elevated temperature conditions, differences in mechanical performances arose between each material variant. This was found to be instigated by microstructural variations exposed through microscopic and Energy Dispersive X-ray Spectroscopy (EDS analysis. SPT results were also compared with available uniaxial tensile data in terms of SPT peak and yield load against uniaxial ultimate tensile and yield strength.

  7. Defense High-Level Waste Leaching Mechanisms Program. Final report

    Mendel, J.E. (compiler)

    1984-08-01

    The Defense High-Level Waste Leaching Mechanisms Program brought six major US laboratories together for three years of cooperative research. The participants reached a consensus that solubility of the leached glass species, particularly solubility in the altered surface layer, is the dominant factor controlling the leaching behavior of defense waste glass in a system in which the flow of leachant is constrained, as it will be in a deep geologic repository. Also, once the surface of waste glass is contacted by ground water, the kinetics of establishing solubility control are relatively rapid. The concentrations of leached species reach saturation, or steady-state concentrations, within a few months to a year at 70 to 90/sup 0/C. Thus, reaction kinetics, which were the main subject of earlier leaching mechanisms studies, are now shown to assume much less importance. The dominance of solubility means that the leach rate is, in fact, directly proportional to ground water flow rate. Doubling the flow rate doubles the effective leach rate. This relationship is expected to obtain in most, if not all, repository situations.

  8. Mechanical Fatigue Testing of High Burnup Fuel for Transportation Applications

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-05-01

    This report describes testing designed to determine the ability of high burnup (HBU) (>45 GWd/MTU) spent fuel to maintain its integrity under normal conditions of transportation. An innovative system, Cyclic Integrated Reversible-bending Fatigue Tester (CIRFT), has been developed at Oak Ridge National Laboratory (ORNL) to test and evaluate the mechanical behavior of spent nuclear fuel (SNF) under conditions relevant to storage and transportation. The CIRFT system is composed of a U-frame equipped with load cells for imposing the pure bending loads on the SNF rod test specimen and measuring the in-situ curvature of the fuel rod during bending using a set up with three linear variable differential transformers (LVDTs).

  9. Highly deformable bones: unusual deformation mechanisms of seahorse armor.

    Porter, Michael M; Novitskaya, Ekaterina; Castro-Ceseña, Ana Bertha; Meyers, Marc A; McKittrick, Joanna

    2013-06-01

    Multifunctional materials and devices found in nature serve as inspiration for advanced synthetic materials, structures and robotics. Here, we elucidate the architecture and unusual deformation mechanisms of seahorse tails that provide prehension as well as protection against predators. The seahorse tail is composed of subdermal bony plates arranged in articulating ring-like segments that overlap for controlled ventral bending and twisting. The bony plates are highly deformable materials designed to slide past one another and buckle when compressed. This complex plate and segment motion, along with the unique hardness distribution and structural hierarchy of each plate, provide seahorses with joint flexibility while shielding them against impact and crushing. Mimicking seahorse armor may lead to novel bio-inspired technologies, such as flexible armor, fracture-resistant structures or prehensile robotics. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Self-desiccation mechanism of high-performance concrete.

    Yang, Quan-Bing; Zhang, Shu-Qing

    2004-12-01

    Investigations on the effects of W/C ratio and silica fume on the autogenous shrinkage and internal relative humidity of high performance concrete (HPC), and analysis of the self-desiccation mechanisms of HPC showed that the autogenous shrinkage and internal relative humidity of HPC increases and decreases with the reduction of W/C respectively; and that these phenomena were amplified by the addition of silica fume. Theoretical analyses indicated that the reduction of RH in HPC was not due to shortage of water, but due to the fact that the evaporable water in HPC was not evaporated freely. The reduction of internal relative humidity or the so-called self-desiccation of HPC was chiefly caused by the increase in mole concentration of soluble ions in HPC and the reduction of pore size or the increase in the fraction of micro-pore water in the total evaporable water (T(r)/T(te) ratio).

  11. Slow high-frequency effects in mechanics: problems, solutions, potentials

    Thomsen, Jon Juel

    2005-01-01

    – an apparent change in the stiffness associated with an equilibrium; Biasing – a tendency for a system to move towards a particular state which does not exist or is unstable without HFE; and Smoothening – a tendency for discontinuities to be apparently smeared out by HFE. The effects and a method for analyzing...... and compared: The Method of Direct Separation of Motions, the Method of Averaging, and the Method of Multiple Scales. The tutorial concludes by suggesting that more vibration experts, researchers and students should know about HFE effects, for the benefit not only of general vibration troubleshooting, but also......Strong high-frequency excitation (HFE) may change the ‘slow’ (i.e. effective or average) properties of mechanical systems, e.g. their stiffness, natural frequencies, equilibriums, equilibrium stability, and bifurcation paths. This tutorial describes three general HFE effects: Stiffening...

  12. Slow high-frequency effects in mechanics: problems, solutions, potentials

    Thomsen, Jon Juel

    – an apparent change in the stiffness associated with an equilibrium; Biasing – a tendency for a system to move towards a particular state which does not exist or is unstable without HFE; and Smoothening – a tendency for discontinuities to be apparently smeared out by HFE. The effects and a method for analyzing...... and compared: The Method of Direct Separation of Motions, the Method of Averaging, and the Method of Multiple Scales. The tutorial concludes by suggesting that more vibration experts, researchers and students should know about HFE effects, for the benefit not only of general vibration troubleshooting, but also......Strong high-frequency excitation (HFE) may change the ‘slow’ (i.e. effective or average) properties of mechanical systems, e.g. their stiffness, natural frequencies, equilibriums, equilibrium stability, and bifurcation paths. This tutorial describes three general HFE effects: Stiffening...

  13. High-energy nuclear reaction mechanisms - fission, fragmentation and spallation

    Kaufman, S.B.

    1987-01-01

    Measurements of the correlations in kinetic energy, mass, charge, and angle of coincident fragments formed in high-energy nuclear reactions have helped to characterize the processes of fission, fragmentation and spallation. For example, fission or fission-like two-body breakup mechanisms result in a strong angular correlation between two heavy fragments; in addition, the momentum transfer in the reaction can be deduced from the correlation. Another example is the multiplicity of light charged particles associated with a given heavy fragment, which is a measure of the violence of the collision, thus distinguishing between central and peripheral collisions. A summary of what has been learned about these processes from such studies will be given, along with some suggestions for further experiments

  14. Thermal-mechanical fatigue of high temperature structural materials

    Renauld, Mark Leo

    Experimental and analytical methods were developed to address the effect of thermal-mechanical strain cycling on high temperature structural materials under uniaxial and biaxial stress states. Two materials were used in the investigation, a nickel-base superalloy of low ductility, IN-738LC and a high ductility material, 316 stainless steel. A uniaxial life prediction model for the IN-738LC material was based on tensile hysteresis energy measured in stabilized, mid-life hysteresis loops. Hold-time effects and temperature cycling were incorporated in the hysteresis energy approach. Crack growth analysis was also included in the model to predict the number of TMF cycles to initiate and grow a fatigue crack through the coating. The nickel-base superalloy, IN-738LC, was primarily tested in out-of-phase (OP) TMF with a temperature range from 482-871sp°C (900-1600sp°F) under continuous and compressive hold-time cycling. IN-738LC fatigue specimens were coated either with an aluminide, NiCoCrAlHfSi overlay or CoNiCrAlY overlay coating on the outer surface of the specimen. Metallurgical failure analysis via optical and scanning electron microscopy, was used to characterize failure behavior of both substrate and coating materials. Type 316 SS was subjected to continuous biaxial strain cycling with an in-phase (IP) TMF loading and a temperature range from 399-621sp°C (750-1150sp°F). As a result, a biaxial TMF life prediction model was proposed on the basis of an extended isothermal fatigue model. The model incorporates a frequency effect and phase factors to assess the different damage mechanisms observed during TMF loading. The model was also applied to biaxial TMF data generated on uncoated IN-738LC.

  15. Home advantage in professional tennis

    Koning, Ruud H.

    2011-01-01

    Home advantage is a pervasive phenomenon in sport. It has been established in team sports such as basketball, baseball, American football, and European soccer. Attention to home advantage in individual sports has so far been limited. The aim of this study was to examine home advantage in

  16. SU-F-19A-03: Dosimetric Advantages in Critical Structure Dose Sparing by Using a Multichannel Cylinder in High Dose Rate Brachytherapy to Treat Vaginal Cuff Cancer

    Syh, J; Syh, J; Patel, B; Zhang, J; Wu, H; Rosen, L [Willis-Knighton Cancer Center, Shreveport, LA (United States)

    2014-06-15

    Purpose: The multichannel cylindrical vaginal applicator is a variation of traditional single channel cylindrical vaginal applicator. The multichannel applicator has additional peripheral channels that provide more flexibility in the planning process. The dosimetric advantage is to reduce dose to adjacent organ at risk (OAR) such as bladder and rectum while maintaining target coverage with the dose optimization from additional channels. Methods: Vaginal HDR brachytherapy plans are all CT based. CT images were acquired in 2 mm thickness to keep integrity of cylinder contouring. The CTV of 5mm Rind with prescribed treatment length was reconstructed from 5mm expansion of inserted cylinder. The goal was 95% of CTV covered by 95% of prescribed dose in both single channel planning (SCP)and multichannel planning (MCP) before proceeding any further optimization for dose reduction to critical structures with emphasis on D2cc and V2Gy . Results: This study demonstrated noticeable dose reduction to OAR was apparent in multichannel plans. The D2cc of the rectum and bladder were showing the reduced dose for multichannel versus single channel. The V2Gy of the rectum was 93.72% and 83.79% (p=0.007) for single channel and multichannel respectively (Figure 1 and Table 1). To assure adequate coverage to target while reducing the dose to the OAR without any compromise is the main goal in using multichannel vaginal applicator in HDR brachytherapy. Conclusion: Multichannel plans were optimized using anatomical based inverse optimization algorithm of inverse planning simulation annealing. The optimization solution of the algorithm was to improve the clinical target volume dose coverage while reducing the dose to critical organs such as bladder, rectum and bowels. The comparison between SCP and MCP demonstrated MCP is superior to SCP where the dwell positions were based on geometric array only. It concluded that MCP is preferable and is able to provide certain features superior to SCP.

  17. Microstructural Evolution and Mechanical Behavior of High Temperature Solders: Effects of High Temperature Aging

    Hasnine, M.; Tolla, B.; Vahora, N.

    2018-04-01

    This paper explores the effects of aging on the mechanical behavior, microstructure evolution and IMC formation on different surface finishes of two high temperature solders, Sn-5 wt.% Ag and Sn-5 wt.% Sb. High temperature aging showed significant degradation of Sn-5 wt.% Ag solder hardness (34%) while aging has little effect on Sn-5 wt.% Sb solder. Sn-5 wt.% Ag experienced rapid grain growth as well as the coarsening of particles during aging. Sn-5 wt.% Sb showed a stable microstructure due to solid solution strengthening and the stable nature of SnSb precipitates. The increase of intermetallic compound (IMC) thickness during aging follows a parabolic relationship with time. Regression analysis (time exponent, n) indicated that IMC growth kinetics is controlled by a diffusion mechanism. The results have important implications in the selection of high temperature solders used in high temperature applications.

  18. High Cycle Fatigue Damage Mechanisms of MAR-M 247 Superalloy at High Temperatures

    Šmíd, Miroslav; Horník, Vít; Hutař, Pavel; Hrbáček, K.; Kunz, Ludvík

    2016-01-01

    Roč. 69, č. 2 (2016), s. 393-397 ISSN 0972-2815 R&D Projects: GA TA ČR(CZ) TA04011525; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : High cycle fatigue * S-N curves * Fractography * High temperature * EBSD analysis Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.533, year: 2016

  19. High Q diamond hemispherical resonators: fabrication and energy loss mechanisms

    Bernstein, Jonathan J; Bancu, Mirela G; Bauer, Joseph M; Cook, Eugene H; Kumar, Parshant; Nyinjee, Tenzin; Perlin, Gayatri E; Ricker, Joseph A; Teynor, William A; Weinberg, Marc S; Newton, Eric

    2015-01-01

    We have fabricated polycrystalline diamond hemispheres by hot-filament CVD (HFCVD) in spherical cavities wet-etched into a high temperature glass substrate CTE matched to silicon. Hemispherical resonators 1.4 mm in diameter have a Q of up to 143 000 in the fundamental wineglass mode, for a ringdown time of 2.4 s. Without trimming, resonators have the two degenerate wineglass modes frequency matched as close as 2 Hz, or 0.013% of the resonant frequency (∼16 kHz). Laser trimming was used to match resonant modes on hemispheres to 0.3 Hz. Experimental and FEA energy loss studies on cantilevers and hemispheres examine various energy loss mechanisms, showing that surface related losses are dominant. Diamond cantilevers with a Q of 400 000 and a ringdown time of 15.4 s were measured, showing the potential of polycrystalline diamond films for high Q resonators. These resonators show great promise for use as hemispherical resonant gyroscopes (HRGs) on a chip. (paper)

  20. Mechanical Properties of Heat Affected Zone of High Strength Steels

    Sefcikova, K.; Brtnik, T.; Dolejs, J.; Keltamaki, K.; Topilla, R.

    2015-11-01

    High Strength Steels became more popular as a construction material during last decade because of their increased availability and affordability. On the other hand, even though general use of Advanced High Strength Steels (AHSS) is expanding, the wide utilization is limited because of insufficient information about their behaviour in structures. The most widely used technique for joining steels is fusion welding. The welding process has an influence not only on the welded connection but on the area near this connection, the so-called heat affected zone, as well. For that reason it is very important to be able to determine the properties in the heat affected zone (HAZ). This area of investigation is being continuously developed in dependence on significant progress in material production, especially regarding new types of steels available. There are currently several types of AHSS on the world market. Two most widely used processes for AHSS production are Thermo-Mechanically Controlled Processing (TMCP) and Quenching in connection with Tempering. In the presented study, TMCP and QC steels grade S960 were investigated. The study is focused on the changes of strength, ductility, hardness and impact strength in heat affected zone based on the used amount of heat input.

  1. Reaction mechanism in high energy heavy-ion collisions

    Tanihata, Isao.

    1982-04-01

    The reaction mechanism in high energy heavy-ion collision is discussed. The discussion is mainly based on the experimental data. Empirical equations have been given for the total cross-sections of nucleus-nucleus reactions and the reaction cross-sections. These cross-sections are well described by the geometrical size of the colliding nuclei. The cross-sections are also understood by microscopic calculation. The charged particle multiplicity gives additional information about the geometrical aspect of heavy ion collision. The data suggested that the total energy, independent of projectile size, is most important for determining the multiplicity. The inclusive proton spectrum in a heavy ion collision showed two distinct regions. The one is the fragment region, and the other the participant region. The spectral shapes of inclusive pion spectra are reasonably well explained by the Coulomb interaction of pions with nuclear fragments. The high energy heavy ion reaction occurs in the overlap region of the projectile and target. This has been tested by measuring the number of participants for various reactions. The space and the time structure of the collision are also discussed in this paper as well as the dynamical aspects of the collision. (Kato, T.)

  2. Mechanical Constraints on Flight at High Elevation Decrease Maneuvering Performance of Hummingbirds.

    Segre, Paolo S; Dakin, Roslyn; Read, Tyson J G; Straw, Andrew D; Altshuler, Douglas L

    2016-12-19

    High-elevation habitats offer ecological advantages including reduced competition, predation, and parasitism [1]. However, flying organisms at high elevation also face physiological challenges due to lower air density and oxygen availability [2]. These constraints are expected to affect the flight maneuvers that are required to compete with rivals, capture prey, and evade threats [3-5]. To test how individual maneuvering performance is affected by elevation, we measured the free-flight maneuvers of male Anna's hummingbirds in a large chamber translocated to a high-elevation site and then measured their performance at low elevation. We used a multi-camera tracking system to identify thousands of maneuvers based on body position and orientation [6]. At high elevation, the birds' translational velocities, accelerations, and rotational velocities were reduced, and they used less demanding turns. To determine how mechanical and metabolic constraints independently affect performance, we performed a second experiment to evaluate flight maneuvers in an airtight chamber infused with either normoxic heliox, to lower air density, or nitrogen, to lower oxygen availability. The hypodense treatment caused the birds to reduce their accelerations and rotational velocities, whereas the hypoxic treatment had no significant effect on maneuvering performance. Collectively, these experiments reveal how aerial maneuvering performance changes with elevation, demonstrating that as birds move up in elevation, air density constrains their maneuverability prior to any influence of oxygen availability. Our results support the hypothesis that changes in competitive ability at high elevations are the result of mechanical limits to flight performance [7]. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. High temperature mechanical tests performed on doped fuels

    Dugay, C.; Mocellin, A.; Dehaudt, P.; Sladkoff, M.

    1998-01-01

    The high-temperature compressive deformation of large-grained UO 2 doped with metallic oxides has been investigated and compared with that of pure UO 2 with a standard microstructure. All the specimens are made from a single batch of UO 2 powder. Tests with constant applied strain rate of 20μm.min -1 show that Cr 2 O 3 additions cause a decrease in the flow stress of about 15 MPa compared with the reference material. When reduced in hydrogen at 1500 deg. C the specimens present a peak stress close to the flow stress of the pure UO 2 . Measurements of creep rates are made at 1500 deg. C at applied stresses varying from 20 to 70 MPa. Cr 2 O 3 additions increase the creep-rate, up to several orders of magnitude-change from the pure material to a doped one. All the doped materials exhibit power-law creep with exponents in the range of 4.9 to 6.3. The activation energy varies from 466 to 451 kJ/mol depending on the dopant concentration. The creep of the undoped material is divided into three regimes of deformation depending on stress. At low stresses the strain rate shows a second power dependence on stress. At high stress levels a higher stress dependence is observed. The creep power-law breaks down and an exponential law holds true at higher stresses. The activation energies are found to be 410 and 560 kJ/mol in the low- and high-stress regions respectively. The former value is in good agreement with the grain boundary diffusion energy in stoichiometric polycrystalline uranium dioxide and the latter corresponds to that found for self-diffusion energy of uranium. Creep behaviours are discussed in terms of deformation mechanisms. (author)

  4. Mechanical properties, reliability assessment and design of ceramic components used in high temperature assemblies

    Bendeich, P.J.

    2002-01-01

    The use of ceramic materials in high temperature structural components holds may advantages over conventional materials such as metals. These include high temperature strength, creep resistance, wear resistance, corrosion resistance, and stiffness. The tradeoff for these improved properties is the brittle nature of ceramics and their tendency for catastrophic failure and lack of damage tolerance. In this work some the various strategies available to overcome these limitations are reviewed. These include stochastic design strategies using the Weibull and Batdorf methods of failure probability prediction rather than the more familiar deterministic methods. Fracture mechanics analysis is also used extensively in this work to predict damage tolerance and failure conditions. A range of testing methods was utilised to provide material information for the methods outlined above. These included: flexural strength measurement for the determination of failure probability parameters; fracture toughness measurement using indentation methods and crack growth measurement; thermal expansion measurement; temperature dependant dynamic Young's modulus measurement; and thermal shock testing using a central heating laser. A new inverse method for measuring specific heat was developed and critically examined for practical use. This is particularly valuable in modelling transient thermal conditions for use in thermal shock analysis. A shape optimisation technique utilising a biological growth law was adapted for use with ceramic components utilising failure probability as the objective function. These methods were utilised in the design and subsequent failure analysis of a high temperature hotpress ram. The results of the failure probability analysis showed that the design had a very low probability of failure under normal operating conditions. Fracture mechanics analysis indicated that damage tolerance in the critical retaining bolt mechanism was high with damage likely to cause

  5. Advantages of high b-value diffusion-weighted imaging to diagnose pseudo-responses in patients with recurrent glioma after bevacizumab treatment.

    Yamasaki, Fumiyuki; Kurisu, Kaoru; Aoki, Tomokazu; Yamanaka, Masami; Kajiwara, Yoshinori; Watanabe, Yosuke; Takayasu, Takeshi; Akiyama, Yuji; Sugiyama, Kazuhiko

    2012-10-01

    The diagnosis of pseudo-responses after bevacizumab treatment is difficult. Because diffusion-weighted imaging (DWI) is associated with cell density, it may facilitate the differentiation between true- and pseudo-responses. Furthermore, as high b-value DWI is even more sensitive to diffusion, it has been reported to be diagnostically useful in various clinical settings. Between September 2008 and May 2011, 10 patients (5 males, 5 females; age range 6-65 years) with recurrent glioma were treated with bevacizumab. All underwent pre- and post-treatment MRI including T2- or FLAIR imaging, post-gadolinium contrast T1-weighted imaging, and DWI with b-1000 and b-4000. Response rates were evaluated by MacDonald- and by response assessment in neuro-oncology working group (RANO) criteria. We also assessed the response rate by calculating the size of high intensity areas using high b-value diffusion-weighted criteria. Prognostic factors were evaluated using Kaplan-Meier survival curves (log-rank test). It was easier to identify pseudo-responses with RANO- than MacDonald criteria, however the reduction of edema by bevacizumab rendered the early diagnosis of tumor progression difficult by RANO criteria. In some patients with recurrent glioma treated with bevacizumab, high b-value diffusion-weighted criteria did, while MacDonald- and RANO criteria did not identify pseudo-responses at an early point after the start of therapy. High b-value DWI reflects cell density more accurately than regular b-value DWI. Our findings suggest that in patients with recurrent glioma, high b-value diffusion-weighted criteria are useful for the differentiation between pseudo- and true responses to treatment with bevacizumab. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  6. Advantages of high b-value diffusion-weighted imaging to diagnose pseudo-responses in patients with recurrent glioma after bevacizumab treatment

    Yamasaki, Fumiyuki; Kurisu, Kaoru; Aoki, Tomokazu; Yamanaka, Masami; Kajiwara, Yoshinori; Watanabe, Yosuke; Takayasu, Takeshi; Akiyama, Yuji; Sugiyama, Kazuhiko

    2012-01-01

    Background: The diagnosis of pseudo-responses after bevacizumab treatment is difficult. Because diffusion-weighted imaging (DWI) is associated with cell density, it may facilitate the differentiation between true- and pseudo-responses. Furthermore, as high b-value DWI is even more sensitive to diffusion, it has been reported to be diagnostically useful in various clinical settings. Materials and methods: Between September 2008 and May 2011, 10 patients (5 males, 5 females; age range 6–65 years) with recurrent glioma were treated with bevacizumab. All underwent pre- and post-treatment MRI including T2- or FLAIR imaging, post-gadolinium contrast T1-weighted imaging, and DWI with b-1000 and b-4000. Response rates were evaluated by MacDonald- and by response assessment in neuro-oncology working group (RANO) criteria. We also assessed the response rate by calculating the size of high intensity areas using high b-value diffusion-weighted criteria. Prognostic factors were evaluated using Kaplan–Meier survival curves (log-rank test). Results: It was easier to identify pseudo-responses with RANO- than MacDonald criteria, however the reduction of edema by bevacizumab rendered the early diagnosis of tumor progression difficult by RANO criteria. In some patients with recurrent glioma treated with bevacizumab, high b-value diffusion-weighted criteria did, while MacDonald- and RANO criteria did not identify pseudo-responses at an early point after the start of therapy. Discussion and conclusion: High b-value DWI reflects cell density more accurately than regular b-value DWI. Our findings suggest that in patients with recurrent glioma, high b-value diffusion-weighted criteria are useful for the differentiation between pseudo- and true responses to treatment with bevacizumab

  7. Mechanical Design of High Lift Systems for High Aspect Ratio Swept Wings

    Rudolph, Peter K. C.

    1998-01-01

    The NASA Ames Research Center is working to develop a methodology for the optimization and design of the high lift system for future subsonic airliners with the involvement of two partners. Aerodynamic analysis methods for two dimensional and three dimensional wing performance with flaps and slats deployed are being developed through a grant with the aeronautical department of the University of California Davis, and a flap and slat mechanism design procedure is being developed through a contract with PKCR, Inc., of Seattle, WA. This report documents the work that has been completed in the contract with PKCR on mechanism design. Flap mechanism designs have been completed for seven (7) different mechanisms with a total of twelve (12) different layouts all for a common single slotted flap configuration. The seven mechanisms are as follows: Simple Hinge, Upside Down/Upright Four Bar Linkage (two layouts), Upside Down Four Bar Linkages (three versions), Airbus A330/340 Link/Track Mechanism, Airbus A320 Link/Track Mechanism (two layouts), Boeing Link/Track Mechanism (two layouts), and Boeing 767 Hinged Beam Four Bar Linkage. In addition, a single layout has been made to investigate the growth potential from a single slotted flap to a vane/main double slotted flap using the Boeing Link/Track Mechanism. All layouts show Fowler motion and gap progression of the flap from stowed to a fully deployed position, and evaluations based on spanwise continuity, fairing size and number, complexity, reliability and maintainability and weight as well as Fowler motion and gap progression are presented. For slat design, the options have been limited to mechanisms for a shallow leading edge slat. Three (3) different layouts are presented for maximum slat angles of 20 deg, 15 deg and 1O deg all mechanized with a rack and pinion drive similar to that on the Boeing 757 airplane. Based on the work of Ljungstroem in Sweden, this type of slat design appears to shift the lift curve so that

  8. Application, advantages and limitations of high-density gravimetric surveys compared with three-dimensional geological modelling in dolomite stability investigations

    Breytenbach, I J; Bosch, P J A

    2011-01-01

    The article discusses the nature of the gravimetric survey as applied and used in dolomite stability investigations on areas underlain by the Chuniespoort Group in South Africa. A short discussion is given on the gravimetric survey procedure along with its uses and alternative methods. Finally, two case studies illustrate the application of the method on a high-density survey grid spacing in comparison with three-dimensional geological modelling based on the lithology and karst weathering hor...

  9. A mechanical microcompressor for high resolution imaging of motile specimens.

    Zinskie, Jessica A; Shribak, Michael; Bruist, Michael F; Aufderheide, Karl J; Janetopoulos, Chris

    2015-10-01

    In order to obtain fine details in 3 dimensions (3D) over time, it is critical for motile biological specimens to be appropriately immobilized. Of the many immobilization options available, the mechanical microcompressor offers many benefits. Our device, previously described, achieves gentle flattening of a cell, allowing us to image finely detailed structures of numerous organelles and physiological processes in living cells. We have imaged protozoa and other small metazoans using differential interference contrast (DIC) microscopy, orientation-independent (OI) DIC, and real-time birefringence imaging using a video-enhanced polychromatic polscope. We also describe an enhancement of our previous design by engineering a new device where the coverslip mount is fashioned onto the top of the base; so the entire apparatus is accessible on top of the stage. The new location allows for easier manipulation of the mount when compressing or releasing a specimen on an inverted microscope. Using this improved design, we imaged immobilized bacteria, yeast, paramecia, and nematode worms and obtained an unprecedented view of cell and specimen details. A variety of microscopic techniques were used to obtain high resolution images of static and dynamic cellular and physiological events. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Statistical mechanics of high-density bond percolation

    Timonin, P. N.

    2018-05-01

    High-density (HD) percolation describes the percolation of specific κ -clusters, which are the compact sets of sites each connected to κ nearest filled sites at least. It takes place in the classical patterns of independently distributed sites or bonds in which the ordinary percolation transition also exists. Hence, the study of series of κ -type HD percolations amounts to the description of classical clusters' structure for which κ -clusters constitute κ -cores nested one into another. Such data are needed for description of a number of physical, biological, and information properties of complex systems on random lattices, graphs, and networks. They range from magnetic properties of semiconductor alloys to anomalies in supercooled water and clustering in biological and social networks. Here we present the statistical mechanics approach to study HD bond percolation on an arbitrary graph. It is shown that the generating function for κ -clusters' size distribution can be obtained from the partition function of the specific q -state Potts-Ising model in the q →1 limit. Using this approach we find exact κ -clusters' size distributions for the Bethe lattice and Erdos-Renyi graph. The application of the method to Euclidean lattices is also discussed.

  11. High-resolution analysis of the mechanical behavior of tissue

    Hudnut, Alexa W.; Armani, Andrea M.

    2017-06-01

    The mechanical behavior and properties of biomaterials, such as tissue, have been directly and indirectly connected to numerous malignant physiological states. For example, an increase in the Young's Modulus of tissue can be indicative of cancer. Due to the heterogeneity of biomaterials, it is extremely important to perform these measurements using whole or unprocessed tissue because the tissue matrix contains important information about the intercellular interactions and the structure. Thus, developing high-resolution approaches that can accurately measure the elasticity of unprocessed tissue samples is of great interest. Unfortunately, conventional elastography methods such as atomic force microscopy, compression testing, and ultrasound elastography either require sample processing or have poor resolution. In the present work, we demonstrate the characterization of unprocessed salmon muscle using an optical polarimetric elastography system. We compare the results of compression testing within different samples of salmon skeletal muscle with different numbers of collagen membranes to characterize differences in heterogeneity. Using the intrinsic collagen membranes as markers, we determine the resolution of the system when testing biomaterials. The device reproducibly measures the stiffness of the tissues at variable strains. By analyzing the amount of energy lost by the sample during compression, collagen membranes that are 500 μm in size are detected.

  12. In vivo photoacoustics and high frequency ultrasound imaging of mechanical high intensity focused ultrasound (HIFU) ablation.

    Daoudi, Khalid; Hoogenboom, Martijn; den Brok, Martijn; Eikelenboom, Dylan; Adema, Gosse J; Fütterer, Jürgen J; de Korte, Chris L

    2017-04-01

    The thermal effect of high intensity focused ultrasound (HIFU) has been clinically exploited over a decade, while the mechanical HIFU is still largely confined to laboratory investigations. This is in part due to the lack of adequate imaging techniques to better understand the in-vivo pathological and immunological effects caused by the mechanical treatment. In this work, we explore the use of high frequency ultrasound (US) and photoacoustics (PA) as a potential tool to evaluate the effect of mechanical ablation in-vivo , e.g. boiling histotripsy. Two mice bearing a neuroblastoma tumor in the right leg were ablated using an MRI-HIFU system conceived for small animals and monitored using MRI thermometry. High frequency US and PA imaging were performed before and after the HIFU treatment. Afterwards, the tumor was resected for further assessment and evaluation of the ablated region using histopathology. High frequency US imaging revealed the presence of liquefied regions in the treated area together with fragmentized tissue which appeared with different reflecting proprieties compared to the surrounding tissue. Photoacoustic imaging on the other hand revealed the presence of deoxygenated blood within the tumor after the ablation due to the destruction of blood vessel network while color Doppler imaging confirmed the blood vessel network destruction within the tumor. The treated area and the presence of red blood cells detected by photoacoustics were further confirmed by the histopathology. This feasibility study demonstrates the potential of high frequency US and PA approach for assessing in-vivo the effect of mechanical HIFU tumor ablation.

  13. Analysing the Advantages of High Temporal Resolution Geostationary MSG SEVIRI Data Compared to Polar Operational Environmental Satellite Data for Land Surface Monitoring in Africa

    Fensholt, R.; Anyamba, A.; Huber, S.; Proud, S. R.; Tucker, C. J.; Small, J.; Pak, E.; Rasmussen, M. O.; Sandholt, I.; Shisanya, C.

    2011-01-01

    Since 1972, satellite remote sensing of the environment has been dominated by polar-orbiting sensors providing useful data for monitoring the earth s natural resources. However their observation and monitoring capacity are inhibited by daily to monthly looks for any given ground surface which often is obscured by frequent and persistent cloud cover creating large gaps in time series measurements. The launch of the Meteosat Second Generation (MSG) satellite into geostationary orbit has opened new opportunities for land surface monitoring. The Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument on-board MSG with an imaging capability every 15 minutes which is substantially greater than any temporal resolution that can be obtained from existing polar operational environmental satellites (POES) systems currently in use for environmental monitoring. Different areas of the African continent were affected by droughts and floods in 2008 caused by periods of abnormally low and high rainfall, respectively. Based on the effectiveness of monitoring these events from Earth Observation (EO) data the current analyses show that the new generation of geostationary remote sensing data can provide higher temporal resolution cloud-free (less than 5 days) measurements of the environment as compared to existing POES systems. SEVIRI MSG 5-day continental scale composites will enable rapid assessment of environmental conditions and improved early warning of disasters for the African continent such as flooding or droughts. The high temporal resolution geostationary data will complement existing higher spatial resolution polar-orbiting satellite data for various dynamic environmental and natural resource applications of terrestrial ecosystems.

  14. Competitive advantage and corporate communications

    Mitić Sanja

    2013-01-01

    Full Text Available Strategic importance of corporate communications and its role in the development of competitive advantage has attracted interest of numerous researchers in the fields of organization, management, marketing and public relations. Recent studies particularly emphasise the growing importance of soft factors, such as reputation in the development of competitive advantage. Concept of reputation is strongly connected with stakeholder theory, which stresses the importance of corporate communications for competitive advantage of firms. The paper focuses on competitive advantage and the link among strategy, reputation and corporate communications.

  15. Analysing the advantages of high temporal resolution geostationary MSG SEVIRI data compared to Polar operational environmental satellite data for land surface monitoring in Africa

    Fensholt, Rasmus; Anyamba, Assaf; Huber Gharib, Silvia

    2011-01-01

    Since 1972, satellite remote sensing of the environment has been dominated by polar-orbiting sensors providing useful data for monitoring the earth’s natural resources. However their observation and monitoring capacity are inhibited by daily to monthly looks for any given ground surface which often...... is obscured by frequent and persistent cloud cover creating large gaps in time series measurements. The launch of the Meteosat Second Generation (MSG) satellite into geostationary orbit has opened new opportunities for land surface monitoring. The Spinning Enhanced Visible and Infrared Imager (SEVIRI...... affected by droughts and floods in 2008 caused by periods of abnormally low and high rainfall, respectively. Based on the effectiveness of monitoring these events from Earth Observation (EO) data the current analyses show that the new generation of geostationary remote sensing data can provide higher...

  16. Advantages of a Vertical High-Resolution Distributed-Temperature-Sensing System Used to Evaluate the Thermal Behavior of Green Roofs

    Hausner, M. B.; Suarez, F. I.; Cousiño, J. A.; Victorero, F.; Bonilla, C. A.; Gironas, J. A.; Vera, S.; Bustamante, W.; Rojas, V.; Leiva, E.; Pasten, P.

    2015-12-01

    Technological innovations used for sustainable urban development, green roofs offer a range of benefits, including reduced heat island effect, rooftop runoff, roof surface temperatures, energy consumption, and noise levels inside buildings, as well as increased urban biodiversity. Green roofs feature layered construction, with the most important layers being the vegetation and the substrate layers located above the traditional roof. These layers provide both insulation and warm season cooling by latent heat flux, reducing the thermal load to the building. To understand and improve the processes driving this thermal energy reduction, it is important to observe the thermal dynamics of a green roof at the appropriate spatial and temporal scales. Traditionally, to observe the thermal behavior of green roofs, a series of thermocouples have been installed at discrete depths within the layers of the roof. Here, we present a vertical high-resolution distributed-temperature-sensing (DTS) system installed in different green roof modules of the Laboratory of Vegetated Infrastructure for Buildings (LIVE -its acronym in Spanish) of the Pontifical Catholic University of Chile. This DTS system allows near-continuous measurement of the thermal profile at spatial and temporal resolutions of approximately 1 cm and 30 s, respectively. In this investigation, the temperature observations from the DTS system are compared with the measurements of a series of thermocouples installed in the green roofs. This comparison makes it possible to assess the value of thermal observations at better spatial and temporal resolutions. We show that the errors associated with lower resolution observations (i.e., from the thermocouples) are propagated in the calculations of the heat fluxes through the different layers of the green roof. Our results highlight the value of having a vertical high-resolution DTS system to observe the thermal dynamics in green roofs.

  17. High fructose diet-induced metabolic syndrome: Pathophysiological mechanism and treatment by traditional Chinese medicine.

    Pan, Ying; Kong, Ling-Dong

    2018-04-01

    Fructose is a natural monosaccharide broadly used in modern society. Over the past few decades, epidemiological studies have demonstrated that high fructose intake is an etiological factor of metabolic syndrome (MetS). This review highlights research advances on fructose-induced MetS, especially the underlying pathophysiological mechanism as well as pharmacotherapy by traditional Chinese medicine (TCM), using the PubMed, Web of science, China National Knowledge Infrastructure, China Science and Technology Journal and Wanfang Data. This review focuses on de novo lipogenesis (DNL) and uric acid (UA) production, two unique features of fructolysis different from glucose glycolysis. High level of DNL and UA production can result in insulin resistance, the key pathological event in developing MetS, mostly through oxidative stress and inflammation. Some other pathologies like the disturbance in brain and gut microbiota in the development of fructose-induced MetS in the past years, are also discussed. In management of MetS, TCM is an excellent representative in alternative and complementary medicine with a complete theory system and substantial herbal remedies. TCMs against MetS or MetS components, including Chinese patent medicines, TCM compound formulas, single TCM herbs and active compounds of TCM herbs, are reviewed on their effects and molecular mechanisms. TCMs with hypouricemic activity, which specially target fructose-induced MetS, are highlighted. And new technologies and strategies (such as high-throughput assay and systems biology) in this field are further discussed. In summary, fructose-induced MetS is a multifactorial disorder with the underlying complex mechanisms. Current clinical and pre-clinical evidence supports the potential of TCMs in management of MetS. Additionally, TCMs may show some advantages against complex MetS as their holistic feature through multiple target actions. However, further work is needed to confirm the effectivity and safety of TCMs

  18. Mechanical characterization of alloys in extreme conditions of high strain rates and high temperature

    Cadoni, Ezio

    2018-03-01

    The aim of this paper is the description of the mechanical characterization of alloys under extreme conditions of temperature and loading. In fact, in the frame of the Cost Action CA15102 “Solutions for Critical Raw Materials Under Extreme Conditions (CRM-EXTREME)” this aspect is crucial and many industrial applications have to consider the dynamic response of materials. Indeed, for a reduction and substitution of CRMs in alloys is necessary to design the materials and understand if the new materials behave better or if the substitution or reduction badly affect their performance. For this reason, a deep knowledge of the mechanical behaviour at high strain-rates of considered materials is required. In general, machinery manufacturing industry or transport industry as well as energy industry have important dynamic phenomena that are simultaneously affected by extended strain, high strain-rate, damage and pressure, as well as conspicuous temperature gradients. The experimental results in extreme conditions of high strain rate and high temperature of an austenitic stainless steel as well as a high-chromium tempered martensitic reduced activation steel Eurofer97 are presented.

  19. Weld Metallurgy and Mechanical Properties of High Manganese Ultra-high Strength Steel Dissimilar Welds

    Dahmen, Martin; Lindner, Stefan; Monfort, Damien; Petring, Dirk

    The increasing demand for ultra-high strength steels in vehicle manufacturing leads to the application of new alloys. This poses a challenge on joining especially by fusion welding. A stainless high manganese steel sheet with excellent strength and deformation properties stands in the centre of the development. Similar and dissimilar welds with a metastable austenitic steel and a hot formed martensitic stainless steel were performed. An investigation of the mixing effects on the local microstructure and the hardness delivers the metallurgical features of the welds. Despite of carbon contents above 0.4 wt.% none of the welds have shown cracks. Mechanical properties drawn from tensile tests deliver high breaking forces enabling a high stiffness of the joints. The results show the potential for the application of laser beam welding for joining in assembly of structural parts.

  20. Electro-optic deflectors deliver advantages over acousto-optical deflectors in a high resolution, ultra-fast force-clamp optical trap.

    Woody, Michael S; Capitanio, Marco; Ostap, E Michael; Goldman, Yale E

    2018-04-30

    We characterized experimental artifacts arising from the non-linear response of acousto-optical deflectors (AODs) in an ultra-fast force-clamp optical trap and have shown that using electro-optical deflectors (EODs) instead eliminates these artifacts. We give an example of the effects of these artifacts in our ultra-fast force clamp studies of the interaction of myosin with actin filaments. The experimental setup, based on the concept of Capitanio et al. [Nat. Methods 9, 1013-1019 (2012)] utilizes a bead-actin-bead dumbbell held in two force-clamped optical traps which apply a load to the dumbbell to move it at a constant velocity. When myosin binds to actin, the filament motion stops quickly as the total force from the optical traps is transferred to the actomyosin attachment. We found that in our setup, AODs were unsuitable for beam steering due to non-linear variations in beam intensity and deflection angle as a function of driving frequency, likely caused by low-amplitude standing acoustic waves in the deflectors. These aberrations caused instability in the force feedback loops leading to artifactual jumps in the trap position. We demonstrate that beam steering with EODs improves the performance of our instrument. Combining the superior beam-steering capability of the EODs, force acquisition via back-focal-plane interferometry, and dual high-speed FPGA-based feedback loops, we apply precise and constant loads to study the dynamics of interactions between actin and myosin. The same concept applies to studies of other biomolecular interactions.

  1. [Advantages and disadvantages of incorporating qualitative methodology in the evaluation of health services. A practical case: evaluation of a high-resolution clinic].

    Alvarez Del Arco, D; Rodríguez Rieiro, C; Sanchidrián De Blás, C; Alejos, B; Plá Mestre, R

    2012-01-01

    We examined the usefulness of incorporating a qualitative phase in the evaluation of the quality of care in a high-resolution medical service carried out with quantitative methods. A quantitative research was performed using a structured questionnaire and selecting interviewees by systematic randomized sampling methods (n=320). In addition, a qualitative research was carried on through semi-structured interviews with patients selected by convenience criteria (n=11), observations in the care assistance circuit, and a group interview with health professionals working in the service. A multidisciplinary research team conducted an individual analysis of the information collected in both quantitative and qualitative phases. Subsequently, three meetings based on group brainstorming techniques were held to identify the diverse contributions of each of the methodologies employed to the research, using affinity graphs to analyse the different results obtained in both phases and evaluate possible bias arising from the use of qualitative methods. Qualitative research allowed examining specific aspects of the health care service that had been collected in the quantitative phase, harmonizing the results obtained in the previous phase, giving in-depth data on the reasons for patient dissatisfaction with specific aspects, such as waiting times and available infrastructures, and identifying emerging issues of the service which had not been previously assessed. Overall, the qualitative phase enriched the results of the research. It is appropriate and recommendable to incorporate this methodological approach in research aimed at evaluating the quality of the service in specific health care settings, since it is provided first hand, by the voice of the customer. Copyright © 2011 SECA. Published by Elsevier Espana. All rights reserved.

  2. Effect of steel fibres on mechanical properties of high-strength concrete

    Holschemacher, K.; Mueller, T.; Ribakov, Y.

    2010-01-01

    Steel fibre reinforced concrete (SFRC) became in the recent decades a very popular and attractive material in structural engineering because of its good mechanical performance. The most important advantages are hindrance of macrocracks' development, delay in microcracks' propagation to macroscopic level and the improved ductility after microcracks' formation. SFRC is also tough and demonstrates high residual strengths after appearing of the first crack. This paper deals with a role of steel fibres having different configuration in combination with steel bar reinforcement. It reports on results of an experimental research program that was focused on the influence of steel fibre types and amounts on flexural tensile strength, fracture behaviour and workability of steel bar reinforced high-strength concrete beams. In the frame of the research different bar reinforcements (2o6 mm and 2o12 mm) and three types of fibres' configurations (two straight with end hooks with different ultimate tensile strength and one corrugated) were used. Three different fibre contents were applied. Experiments show that for all selected fibre contents a more ductile behaviour and higher load levels in the post-cracking range were obtained. The study forms a basis for selection of suitable fibre types and contents for their most efficient combination with regular steel bar reinforcement.

  3. Nuclear-Mechanical Coupling: Small Amplitude Mechanical Vibrations and High Amplitude Power Oscillations in Nuclear Reactors

    Suarez Antola, R.

    2008-11-01

    The cores of nuclear reactors, including its structural parts and cooling fluids, are complex mechanical systems able to vibrate in a set of normal modes and frequencies, if suitable perturbed. The cyclic variations in the strain state of the core materials may produce changes in density. Changes in density modify the reactivity. Changes in reactivity modify thermal power. Modifications in thermal power produce variations in temperature fields. Variations in temperature produce variations in strain due to thermal-elastic effects. If the variation of the temperature field is fast enough and if the Doppler Effect and other stabilizing prompt effects in the fuel are weak enough, a fast oscillatory instability could be produced, coupled with mechanical vibrations of small amplitude. A recently constructed, simple mathematical model of nuclear reactor kinetics, that improves the one due to A.S. Thompson, is reviewed. It was constructed in order to study, in a first approximation, the stability of the reactor: a nonlinear nuclear-thermal oscillator (that corresponds to reactor point kinetics with thermal-elastic feedback and with frozen delayed neutron effects) is coupled nonlinearly with a linear mechanical-thermal oscillator (that corresponds to the first normal mode of mechanical vibrations excited by thermo-elastic effects). This mathematical model is studied here from the standpoint of mechanical vibrations. It is shown how, under certain conditions, a suitable mechanical perturbation could elicit fast and growing oscillatory instabilities in the reactor power. Applying the asymptotic method due to Krylov, Bogoliubov and Mitropolsky, analytical formulae that may be used in the calculation of the time varying amplitude and phase of the mechanical oscillations are given, as functions of the mechanical, thermal and nuclear parameters of the reactor. The consequences for the mechanical integrity of the reactor are assessed. Some conditions, mainly, but not exclusively

  4. Synthetic oligorotaxanes exert high forces when folding under mechanical load

    Sluysmans, Damien; Hubert, Sandrine; Bruns, Carson J.; Zhu, Zhixue; Stoddart, J. Fraser; Duwez, Anne-Sophie

    2018-01-01

    Folding is a ubiquitous process that nature uses to control the conformations of its molecular machines, allowing them to perform chemical and mechanical tasks. Over the years, chemists have synthesized foldamers that adopt well-defined and stable folded architectures, mimicking the control expressed by natural systems1,2. Mechanically interlocked molecules, such as rotaxanes and catenanes, are prototypical molecular machines that enable the controlled movement and positioning of their component parts3-5. Recently, combining the exquisite complexity of these two classes of molecules, donor-acceptor oligorotaxane foldamers have been synthesized, in which interactions between the mechanically interlocked component parts dictate the single-molecule assembly into a folded secondary structure6-8. Here we report on the mechanochemical properties of these molecules. We use atomic force microscopy-based single-molecule force spectroscopy to mechanically unfold oligorotaxanes, made of oligomeric dumbbells incorporating 1,5-dioxynaphthalene units encircled by cyclobis(paraquat-p-phenylene) rings. Real-time capture of fluctuations between unfolded and folded states reveals that the molecules exert forces of up to 50 pN against a mechanical load of up to 150 pN, and displays transition times of less than 10 μs. While the folding is at least as fast as that observed in proteins, it is remarkably more robust, thanks to the mechanically interlocked structure. Our results show that synthetic oligorotaxanes have the potential to exceed the performance of natural folding proteins.

  5. Microstructural evolutions and mechanical behaviour of the nickel based alloys 617 and 230 at high temperature

    Chomette, S.

    2009-11-01

    properties at 850 C and 950 C have been evaluated using several stress levels (creep), strain rates (tensile) and relaxation duration (fatigue). The effects of initial treatments have also been studied, i.e. ageing treatments effects on creep and tensile properties and cold-work effects on creep properties. At high temperature, the as received Inconel 617 does not show classical creep behaviour. This study shows the importance of the fast carbides precipitation on their mechanical properties, despite the fact that the Inconel 617 and the Haynes 230 are listed as solid solution alloys. Low cycle fatigue tests with and without holding time have been performed at 850 C under air and under vacuum on both alloys. The results showed that cyclic hardening, cyclic stability and life time are closely related to the duration of the holding time. Furthermore, a single thermally activated mechanism operates over a very wide range of strain rates, corresponding to tensile tests, creep and relaxation. The link between microstructure and mechanical behaviour presented in this thesis helps to determine the advantages as the operation limits of each alloy in order to manufacture a nuclear power plant heat exchanger. (author)

  6. Advantaged Bidders in Franchise Auctions

    van den Berg, V.A.C.

    2012-01-01

    Consider a government that auctions a franchise for, e.g., an airport, telecommunication network, or utility. Consider an 'incumbent bidder' that owns a complement or substitute. With an auction on the transfer (i.e. payment) to the government, the incumbent is advantaged.If the government regulates the market with an auction on the price asked to consumers, it depends who is advantaged. With complements, the incumbent is advantaged: it can set a lower price on the new franchise, as this inc...

  7. A microbial model of economic trading and comparative advantage.

    Enyeart, Peter J; Simpson, Zachary B; Ellington, Andrew D

    2015-01-07

    The economic theory of comparative advantage postulates that beneficial trading relationships can be arrived at by two self-interested entities producing the same goods as long as they have opposing relative efficiencies in producing those goods. The theory predicts that upon entering trade, in order to maximize consumption both entities will specialize in producing the good they can produce at higher efficiency, that the weaker entity will specialize more completely than the stronger entity, and that both will be able to consume more goods as a result of trade than either would be able to alone. We extend this theory to the realm of unicellular organisms by developing mathematical models of genetic circuits that allow trading of a common good (specifically, signaling molecules) required for growth in bacteria in order to demonstrate comparative advantage interactions. In Conception 1, the experimenter controls production rates via exogenous inducers, allowing exploration of the parameter space of specialization. In Conception 2, the circuits self-regulate via feedback mechanisms. Our models indicate that these genetic circuits can demonstrate comparative advantage, and that cooperation in such a manner is particularly favored under stringent external conditions and when the cost of production is not overly high. Further work could involve implementing the models in living bacteria and searching for naturally occurring cooperative relationships between bacteria that conform to the principles of comparative advantage. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Application of High-Density Electropulsing to Improve the Performance of Metallic Materials: Mechanisms, Microstructure and Properties

    Yinying Sheng

    2018-01-01

    Full Text Available The technology of high-density electropulsing has been applied to increase the performance of metallic materials since the 1990s and has shown significant advantages over traditional heat treatment in many aspects. However, the microstructure changes in electropulsing treatment (EPT metals and alloys have not been fully explored, and the effects vary significantly on different material. When high-density electrical pulses are applied to metals and alloys, the input of electric energy and thermal energy generally leads to structural rearrangements, such as dynamic recrystallization, dislocation movements and grain refinement. The enhanced mechanical properties of the metals and alloys after high-density electropulsing treatment are reflected by the significant improvement of elongation. As a result, this technology holds great promise in improving the deformation limit and repairing cracks and defects in the plastic processing of metals. This review summarizes the effect of high-density electropulsing treatment on microstructural properties and, thus, the enhancement in mechanical strength, hardness and corrosion performance of metallic materials. It is noteworthy that the change of some properties can be related to the structure state before EPT (quenched, annealed, deformed or others. The mechanisms for the microstructural evolution, grain refinement and formation of oriented microstructures of different metals and alloys are presented. Future research trends of high-density electrical pulse technology for specific metals and alloys are highlighted.

  9. Application of High-Density Electropulsing to Improve the Performance of Metallic Materials: Mechanisms, Microstructure and Properties.

    Sheng, Yinying; Hua, Youlu; Wang, Xiaojian; Zhao, Xueyang; Chen, Lianxi; Zhou, Hanyu; Wang, James; Berndt, Christopher C; Li, Wei

    2018-01-24

    The technology of high-density electropulsing has been applied to increase the performance of metallic materials since the 1990s and has shown significant advantages over traditional heat treatment in many aspects. However, the microstructure changes in electropulsing treatment (EPT) metals and alloys have not been fully explored, and the effects vary significantly on different material. When high-density electrical pulses are applied to metals and alloys, the input of electric energy and thermal energy generally leads to structural rearrangements, such as dynamic recrystallization, dislocation movements and grain refinement. The enhanced mechanical properties of the metals and alloys after high-density electropulsing treatment are reflected by the significant improvement of elongation. As a result, this technology holds great promise in improving the deformation limit and repairing cracks and defects in the plastic processing of metals. This review summarizes the effect of high-density electropulsing treatment on microstructural properties and, thus, the enhancement in mechanical strength, hardness and corrosion performance of metallic materials. It is noteworthy that the change of some properties can be related to the structure state before EPT (quenched, annealed, deformed or others). The mechanisms for the microstructural evolution, grain refinement and formation of oriented microstructures of different metals and alloys are presented. Future research trends of high-density electrical pulse technology for specific metals and alloys are highlighted.

  10. Application of High-Density Electropulsing to Improve the Performance of Metallic Materials: Mechanisms, Microstructure and Properties

    Sheng, Yinying; Hua, Youlu; Zhao, Xueyang; Chen, Lianxi; Zhou, Hanyu; Wang, James; Berndt, Christopher C.; Li, Wei

    2018-01-01

    The technology of high-density electropulsing has been applied to increase the performance of metallic materials since the 1990s and has shown significant advantages over traditional heat treatment in many aspects. However, the microstructure changes in electropulsing treatment (EPT) metals and alloys have not been fully explored, and the effects vary significantly on different material. When high-density electrical pulses are applied to metals and alloys, the input of electric energy and thermal energy generally leads to structural rearrangements, such as dynamic recrystallization, dislocation movements and grain refinement. The enhanced mechanical properties of the metals and alloys after high-density electropulsing treatment are reflected by the significant improvement of elongation. As a result, this technology holds great promise in improving the deformation limit and repairing cracks and defects in the plastic processing of metals. This review summarizes the effect of high-density electropulsing treatment on microstructural properties and, thus, the enhancement in mechanical strength, hardness and corrosion performance of metallic materials. It is noteworthy that the change of some properties can be related to the structure state before EPT (quenched, annealed, deformed or others). The mechanisms for the microstructural evolution, grain refinement and formation of oriented microstructures of different metals and alloys are presented. Future research trends of high-density electrical pulse technology for specific metals and alloys are highlighted. PMID:29364844

  11. Innovation strategies and competitive advantage

    Gërguri, Shqipe; Rexhepi, Gadaf; Ramadani, Veland

    2013-01-01

    Companies today operate in a very dynamic, uncertain and competitive environment. They compete in "nicety" that are so small but so important. Companies are trying to achieve competitive advantage in order to help them obtain a better and a stable position in the marketplace. The best way for companies to achieve a competitive advantage is through innovation. This paper addresses the meaning of innovation what does innovation present, types of innovation specifically discussing the right way ...

  12. Perceived versus Actual Competitive Advantage

    Langemeier, Michael R.; Yeager, Elizabeth

    2014-01-01

    This paper examined the relationship between farm characteristics and perceived sources of competitive advantage, and cost-based and revenue-based efficiency indices. Gross farm income and the percentage of labor devoted to crop production were significant and positively correlated with cost and revenue efficiency while the perception of the cowherd being the most important part of the operation was negatively correlated with efficiency. In general, perceived sources of competitive advantage ...

  13. Practical advantages of evolutionary computation

    Fogel, David B.

    1997-10-01

    Evolutionary computation is becoming a common technique for solving difficult, real-world problems in industry, medicine, and defense. This paper reviews some of the practical advantages to using evolutionary algorithms as compared with classic methods of optimization or artificial intelligence. Specific advantages include the flexibility of the procedures, as well as their ability to self-adapt the search for optimum solutions on the fly. As desktop computers increase in speed, the application of evolutionary algorithms will become routine.

  14. Competitive advantage and corporate communications

    Mitić Sanja; Ognjanov Galjina

    2013-01-01

    Strategic importance of corporate communications and its role in the development of competitive advantage has attracted interest of numerous researchers in the fields of organization, management, marketing and public relations. Recent studies particularly emphasise the growing importance of soft factors, such as reputation in the development of competitive advantage. Concept of reputation is strongly connected with stakeholder theory, which stresses the importance of corporate communications ...

  15. STRATEGIES FOR ACHIEVING COMPETITIVE ADVANTAGE

    Jusuf ZEKIRI; Alexandru NEDELEA

    2011-01-01

    This paper is organized in three parts. A brief overview of the importance of strategies within companies, as well as literature review is presented along with traditional approaches on strategies for achieving competitive advantage, and new approaches for gaining a competitive advantage. The main objective of the paper is to outline and discuss the relevant issues and challenges from a theoretical viewpoint related with the possible strategy formulation of companies in order to achieve a com...

  16. Corporate Finance and Comparative Advantage

    Peter Egger; Christian Keuschnigg

    2009-01-01

    Since innovative firms are often financially constrained, access to external funds is important for the expansion of innovative industries. This paper reports four important results. First, comparative advantage is shaped by factor endowments as well as fundamental determinants of corporate finance. In particular, a larger equity ratio of firms and tough governance standards relax finance constraints and create a comparative advantage in innovative industries. Second, factor price equalizatio...

  17. Mechanisms of metallization degradation in high power diodes

    Brincker, Mads; Kristensen, Peter Kjær; Pedersen, Kristian Bonderup

    2016-01-01

    Under operation the topside metallization of power electronic chips is commonly observed to degrade and thereby affecta device's electrical characteristics. However, the mechanisms of the degradation process and the role of environmental factors are not yet fully understood. In this work, we...

  18. Enhancing the Accuracy of Advanced High Temperature Mechanical Testing through Thermography

    Jonathan Jones

    2018-03-01

    Full Text Available This paper describes the advantages and enhanced accuracy thermography provides to high temperature mechanical testing. This technique is not only used to monitor, but also to control test specimen temperatures where the infra-red technique enables accurate non-invasive control of rapid thermal cycling for non-metallic materials. Isothermal and dynamic waveforms are employed over a 200–800 °C temperature range to pre-oxidised and coated specimens to assess the capability of the technique. This application shows thermography to be accurate to within ±2 °C of thermocouples, a standardised measurement technique. This work demonstrates the superior visibility of test temperatures previously unobtainable by conventional thermocouples or even more modern pyrometers that thermography can deliver. As a result, the speed and accuracy of thermal profiling, thermal gradient measurements and cold/hot spot identification using the technique has increased significantly to the point where temperature can now be controlled by averaging over a specified area. The increased visibility of specimen temperatures has revealed additional unknown effects such as thermocouple shadowing, preferential crack tip heating within an induction coil, and, fundamental response time of individual measurement techniques which are investigated further.

  19. The Mechanism of High Ductility for Novel High-Carbon Quenching-Partitioning-Tempering Martensitic Steel

    Qin, Shengwei; Liu, Yu; Hao, Qingguo; Wang, Ying; Chen, Nailu; Zuo, Xunwei; Rong, Yonghua

    2015-09-01

    In this article, a novel quenching-partitioning-tempering (Q-P-T) process was applied to treat Fe-0.6C-1.5Mn-1.5Si-0.6Cr-0.05Nb hot-rolled high-carbon steel and the microstructures including retained austenite fraction and the average dislocation densities in both martensite and retained austenite were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, respectively. The Q-P-T steel exhibits high strength (1950 MPa) and elongation (12.4 pct). Comparing with the steel treated by traditional quenching and tempering (Q&T) process, the mechanism of high ductility for high-carbon Q-P-T steel is revealed as follows. Much more retained austenite existing in Q-P-T steel than in Q&T one remarkably enhances the ductility by the following two effects: the dislocation absorption by retained austenite effect and the transformation-induced plasticity effect. Besides, lower dislocation density in martensite matrix produced by Q-P-T process plays an important role in the improvement of ductility. However, some thin plates of twin-type martensite embedded in dislocation-type martensite matrix in high-carbon Q-P-T steel affect the further improvement of ductility.

  20. High temperature mechanical properties of unirradiated dispersion strengthened copper

    Gentzbittel, J.M.; Rigollet, C.; Robert, G.

    1994-01-01

    Oxide Dispersion Strengthened (ODS) copper material, due to its excellent thermal conductivity associated with a high temperature strength is a candidate material for structural applications as divertor plasma facing components of thermonuclear fusion reactor. Tensile and creep results of oxide dispersion strengthened copper are presented. The most important features of ODS copper high temperature behaviour are the high strength corresponding to low creep rates, high stress creep rate dependence, a poor ductility and a brittleness which result in a premature creep fracture at high applied stress. (R.P.) 2 refs.; 6 figs

  1. Provable quantum advantage in randomness processing

    Dale, H; Jennings, D; Rudolph, T

    2015-01-01

    Quantum advantage is notoriously hard to find and even harder to prove. For example the class of functions computable with classical physics actually exactly coincides with the class computable quantum-mechanically. It is strongly believed, but not proven, that quantum computing provides exponential speed-up for a range of problems, such as factoring. Here we address a computational scenario of "randomness processing" in which quantum theory provably yields, not only resource reduction over c...

  2. High resolution studies of pion-nucleus reaction mechanism

    Morris, C.L.

    1983-01-01

    Pion inelastic scattering is generally well described as a first order process using the DWIA. This is especially true for a large body of inelastic scattering data to low-lying collective states which is well-described by form factors obtained in (e,e') and the DWIA. Some data for which this model does not work are presented. Higher order reaction mechanisms have been invoked to explain some of these data. However, no model of these second order processes gives a satisfactory explanation of the entire data set. Experimentally, more data for pion-induced transitions to low-spin unnatural-parity states which have been studied by other probes would be useful in sorting out the reaction mechanisms responsible for the anomalous cross sections observed for the 1 + states in 12 C. Theoretically, a consistent evaluation of possible second-order diagrams in inelastic scattering, such as is being attempted for DCX 22 , would be useful

  3. A mechanical microcompressor for high resolution imaging of motile specimens

    Zinskie, Jessica A.; Shribak, Michael; Bruist, Michael F.; Aufderheide, Karl J.; Janetopoulos, Chris

    2015-01-01

    In order to obtain fine details in 3 dimensions (3D) over time, it is critical for motile biological specimens to be appropriately immobilized. Of the many immobilization options available, the mechanical microcompressor offers many benefits. Our device, previously described, achieves gentle flattening of a cell, allowing us to image finely detailed structures of numerous organelles and physiological processes in living cells. We have imaged protozoa and other small metazoans using differenti...

  4. Nucleation mechanisms in high energy ion beam induced dewetting

    Haag, Michael; Garmatter, Daniel; Ferhati, Redi; Amirthapandian, Sankarakumar; Bolse, Wolfgang [Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, Universitaet Stuttgart (Germany)

    2011-07-01

    Solid coatings, when heated above their melting points, often break up by forming small round holes, which then grow, coalesce and finally turn the initially contiguous film into a pattern of isolated droplets. Such dewetting has been intensively studied using thin polymer films on Si. Three different hole nucleation mechanisms were discovered: homogeneous (spontaneous) nucleation, heterogeneous nucleation at defects, and spinodal dewetting by self-amplifying capillary waves. We have recently found that swift heavy ion (SHI) irradiation of thin oxide films on Si results in similar dewetting patterns, even though the films were kept far below their melting points. Using our new in-situ SEM at the UNILAC accelerator of GSI, we were now able to identify the mechanisms behind this SHI induced dewetting phenomenon. By varying the film thickness and introducing defects at the interface, we can directly address the hole nucleation processes. Besides homogeneous and heterogeneous nucleation, we also found a process, which very much resembles the spinodal mechanism found for liquid polymers, although in the present case the instable wavy surface is not generated by capillary waves, but by ion beam induced stresses.

  5. High Temperature Mechanical Constitutive Modeling of a High-Nb TiAl Alloy

    DONG Chengli

    2018-02-01

    Full Text Available Uniaxial tensile, low cycle fatigue, fatigue-creep interaction and creep experiments of a novel high-Nb TiAl alloy (i.e. Ti-45Al-8Nb-0.2W-0.2B-0.02Y (atom fraction/% were conducted at 750℃ to obtain its tested data and curves. Based on Chaboche visco-plasticity unified constitutive model, Ohno-Wang modified non-linear kinematic hardening was introduced in Chaboche constitutive model to describe the cyclic hardening/softening, and Kachanov damage was coupled in Chaboche constitutive model to characterize the accelerated creep stage. The differential equations of the constitutive model discretized by explicit Euler method were compiled in to ABAQUS/UMAT to simulate the mechanical behavior of high-Nb TiAl alloy at different test conditions. The results show that Chaboche visco-plasticity unified constitutive model considering both Ohno-Wang modified non-linear kinematic hardening and Kachanov damage is able to simulate the uniaxial tensile, low cycle fatigue, fatigue-creep interaction and creep behavior of high-Nb TiAl alloy and has high accuracy.

  6. How Successful Is Medicare Advantage?

    Newhouse, Joseph P; McGuire, Thomas G

    2014-01-01

    Context Medicare Part C, or Medicare Advantage (MA), now almost 30 years old, has generally been viewed as a policy disappointment. Enrollment has vacillated but has never come close to the penetration of managed care plans in the commercial insurance market or in Medicaid, and because of payment policy decisions and selection, the MA program is viewed as having added to cost rather than saving funds for the Medicare program. Recent changes in Medicare policy, including improved risk adjustment, however, may have changed this picture. Methods This article summarizes findings from our group's work evaluating MA's recent performance and investigating payment options for improving its performance even more. We studied the behavior of both beneficiaries and plans, as well as the effects of Medicare policy. Findings Beneficiaries make “mistakes” in their choice of MA plan options that can be explained by behavioral economics. Few beneficiaries make an active choice after they enroll in Medicare. The high prevalence of “zero-premium” plans signals inefficiency in plan design and in the market's functioning. That is, Medicare premium policies interfere with economically efficient choices. The adverse selection problem, in which healthier, lower-cost beneficiaries tend to join MA, appears much diminished. The available measures, while limited, suggest that, on average, MA plans offer care of equal or higher quality and for less cost than traditional Medicare (TM). In counties, greater MA penetration appears to improve TM's performance. Conclusions Medicare policies regarding lock-in provisions and risk adjustment that were adopted in the mid-2000s have mitigated the adverse selection problem previously plaguing MA. On average, MA plans appear to offer higher value than TM, and positive spillovers from MA into TM imply that reimbursement should not necessarily be neutral. Policy changes in Medicare that reform the way that beneficiaries are charged for MA plan

  7. Energy efficient mechanisms for high-performance Wireless Sensor Networks

    Alsaify, Baha'adnan

    2009-12-01

    Due to recent advances in microelectronics, the development of low cost, small, and energy efficient devices became possible. Those advances led to the birth of the Wireless Sensor Networks (WSNs). WSNs consist of a large set of sensor nodes equipped with communication capabilities, scattered in the area to monitor. Researchers focus on several aspects of WSNs. Such aspects include the quality of service the WSNs provide (data delivery delay, accuracy of data, etc...), the scalability of the network to contain thousands of sensor nodes (the terms node and sensor node are being used interchangeably), the robustness of the network (allowing the network to work even if a certain percentage of nodes fails), and making the energy consumption in the network as low as possible to prolong the network's lifetime. In this thesis, we present an approach that can be applied to the sensing devices that are scattered in an area for Sensor Networks. This work will use the well-known approach of using a awaking scheduling to extend the network's lifespan. We designed a scheduling algorithm that will reduce the delay's upper bound the reported data will experience, while at the same time keeps the advantages that are offered by the use of the awaking scheduling -- the energy consumption reduction which will lead to the increase in the network's lifetime. The wakeup scheduling is based on the location of the node relative to its neighbors and its distance from the Base Station (the terms Base Station and sink are being used interchangeably). We apply the proposed method to a set of simulated nodes using the "ONE Simulator". We test the performance of this approach with three other approaches -- Direct Routing technique, the well known LEACH algorithm, and a multi-parent scheduling algorithm. We demonstrate a good improvement on the network's quality of service and a reduction of the consumed energy.

  8. The Processing and Mechanical Properties of High Temperature/ High Performance Composites. Mechanism-Based Constitutive Laws and Design. Book 1

    1994-03-01

    NTIS CRA&I IDT!C TAB TABLE OF CONTENTS U.11 nulce Distf ib,.tion, I Availab~iity Cojes EXECUTIVE SUMMARY Dist spc :BOOKh1 MECHANISM-BASED...unit cylinders (H=D), but rather by slightly squat cylinders. This is in contrast to the results of Bao et al. [1] in which unit cylinders resulted in

  9. Project safety as a sustainable competitive advantage.

    Rechenthin, David

    2004-01-01

    To be consistently profitable, a construction company must complete projects in scope, on schedule, and on budget. At the same time, the nature of the often high-risk work performed by construction companies can result in high accident rates. Clients and other stakeholders are placing increasing pressure on companies to decrease those accident rates. Clients routinely demand copies of safety plans and evidence of past results at the "pre-qualification" or "request for proposal" stages of the procurement process. Are high accident rates and the associated costs just a part of business? Companies that deliver on scope, schedule, and budget have a competitive advantage. Is it possible for projects with low accident rates to use it as a competitive advantage? Is the value added by safety just a temporary or parity issue, or does a successful safety program offer significant advantage to the company and the client? This article concludes that in the case of a high-risk industry, such as the construction industry, an organization with a successful safety program can promote safety performance as a sustainable competitive advantage. It is a choice the company can make.

  10. High Temperature Degradation Mechanisms in Polymer Matrix Composites

    Cunningham, Ronan A.

    1996-01-01

    Polymer matrix composites are increasingly used in demanding structural applications in which they may be exposed to harsh environments. The durability of such materials is a major concern, potentially limiting both the integrity of the structures and their useful lifetimes. The goal of the current investigation is to develop a mechanism-based model of the chemical degradation which occurs, such that given the external chemical environment and temperatures throughout the laminate, laminate geometry, and ply and/or constituent material properties, we can calculate the concentration of diffusing substances and extent of chemical degradation as functions of time and position throughout the laminate. This objective is met through the development and use of analytical models, coupled to an analysis-driven experimental program which offers both quantitative and qualitative information on the degradation mechanism. Preliminary analyses using a coupled diffusion/reaction model are used to gain insight into the physics of the degradation mechanisms and to identify crucial material parameters. An experimental program is defined based on the results of the preliminary analysis which allows the determination of the necessary material coefficients. Thermogravimetric analyses are carried out in nitrogen, air, and oxygen to provide quantitative information on thermal and oxidative reactions. Powdered samples are used to eliminate diffusion effects. Tests in both inert and oxidative environments allow the separation of thermal and oxidative contributions to specimen mass loss. The concentration dependency of the oxidative reactions is determined from the tests in pure oxygen. Short term isothermal tests at different temperatures are carried out on neat resin and unidirectional macroscopic specimens to identify diffusion effects. Mass loss, specimen shrinkage, the formation of degraded surface layers and surface cracking are recorded as functions of exposure time. Geometry effects

  11. Searching for the Advantages of Virus Sex

    Turner, Paul E.

    2003-02-01

    Sex (genetic exchange) is a nearly universal phenomenon in biological populations. But this is surprising given the costs associated with sex. For example, sex tends to break apart co-adapted genes, and sex causes a female to inefficiently contribute only half the genes to her offspring. Why then did sex evolve? One famous model poses that sex evolved to combat Muller's ratchet, the mutational load that accrues when harmful mutations drift to high frequencies in populations of small size. In contrast, the Fisher-Muller Hypothesis predicts that sex evolved to promote genetic variation that speeds adaptation in novel environments. Sexual mechanisms occur in viruses, which feature high rates of deleterious mutation and frequent exposure to novel or changing environments. Thus, confirmation of one or both hypotheses would shed light on the selective advantages of virus sex. Experimental evolution has been used to test these classic models in the RNA bacteriophage φ6, a virus that experiences sex via reassortment of its chromosomal segments. Empirical data suggest that sex might have originated in φ6 to assist in purging deleterious mutations from the genome. However, results do not support the idea that sex evolved because it provides beneficial variation in novel environments. Rather, experiments show that too much sex can be bad for φ6 promiscuity allows selfish viruses to evolve and spread their inferior genes to subsequent generations. Here I discuss various explanations for the evolution of segmentation in RNA viruses, and the added cost of sex when large numbers of viruses co-infect the same cell.

  12. Antioxidant mechanism of milk mineral-high-affinity iron binding.

    Allen, K; Cornforth, D

    2007-01-01

    Milk mineral (MM), a by-product of whey processing, is an effective antioxidant in meat systems, but the antioxidant mechanism has not been established. MM has been postulated to chelate iron and prevent iron-catalysis of lipid oxidation. The objective of this research was to examine this putative mechanism. MM was compared to sodium tripolyphosphate (STPP), calcium phosphate monobasic (CPM), and calcium pyrophosphate (CPP) to determine iron-binding capacity, sample solubility, and eluate soluble phosphorus after treating samples with a ferrous chloride standard. Scanning electron microscopy with energy-dispersive X-ray analysis was used to localize minerals on iron-treated MM particle surfaces. Histochemical staining for calcium was performed on raw and cooked ground beef samples with added MM. MM bound more iron per gram (P compounds, and was much less soluble (P iron across the MM particle surface, directly demonstrating iron binding to MM particles. Unlike other common chelating agents, such as STPP and citrate, histochemical staining demonstrated that MM remained insoluble in ground beef, even after cooking. The ability of MM to bind iron and remain insoluble may enhance its antioxidant effect by removing iron ions from solution. However, MM particles must be small and well distributed in order to adequately bind iron throughout the food system.

  13. Mechanical Properties of High Cementitious Grout (I)

    Sørensen, Eigil V.

     The present report describes tests carried out on the high performance grout MASTERFLOW 9500, marked WMG 7145 FP, developed by BASF Construction Materials and designed for use in grouted connections of offshore windmill foundations....

  14. Mechanical Properties of High Performance Cementitious Grout Masterflow 9200

    Sørensen, Eigil V.

    The present report describes tests carried out on the high performance grout Masterflow 9200, developed by BASF Construction Chemicals A/S and designed for use in grouted connections of windmill foundations....

  15. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    Haseroth, Helmut; Hora, Heinrich; Regensburg Inst. of Tech.

    1996-01-01

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10 11 C 4+ ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ''hot'' electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author)

  16. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    Haseroth, Helmut [European Organization for Nuclear Research, Geneva (Switzerland); Hora, Heinrich [New South Wales Univ., Kensington, NSW (Australia)]|[Regensburg Inst. of Tech. (Germany). Anwenderzentrum

    1996-12-31

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10{sup 11} C{sup 4+} ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ``hot`` electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author).

  17. Experimental characterization and modelling of UO2 mechanical behaviour at high temperatures and high strain rates

    Salvo, Maxime

    2014-01-01

    The aim of this work is to characterize and model the mechanical behavior of uranium dioxide (UO 2 ) during a Reactivity Initiated Accident (RIA). The fuel loading during a RIA is characterized by high strain rates (up to 1/s) and high temperatures (1000 C - 2500 C). Two types of UO 2 pellets (commercial and high density) were therefore tested in compression with prescribed displacement rates (0.1 to 100 mm/min corresponding to strain rates of 10 -4 - 10 -1 /s) and temperatures (1100 C - 1350 C - 1550 C et 1700 C). Experimental results (geometry, yield stress and microstructure) allowed us to define a hyperbolic sine creep law and a Drucker-Prager criterion with associated plasticity, in order to model grain boundaries fragmentation at the macroscopic scale. Finite Element Simulations of these tests and of more than 200 creep tests were used to assess the model response to a wide range of temperatures (1100 C - 1700 C) and strain rates (10 -9 /s - 10 -1 /s). Finally, a constitutive law called L3F was developed for UO 2 by adding to the previous model irradiation creep and tensile macroscopic cracking. The L3F law was then introduced in the 1.5D scheme of the fuel performance code ALCYONE-RIA to simulate the REP-Na tests performed in the experimental reactor CABRI. Simulation results are in good agreement with post tests examinations. (author) [fr

  18. Autogenous shrinkage in high-performance cement paste: An evaluation of basic mechanisms

    Lura, Pietro; Jensen, Ole Mejlhede; van Breugel, Klaas

    2003-01-01

    In this paper, various mechanisms Suggested to cause autogenous shrinkage are presented. The mechanisms are evaluated from the point of view of their soundness and applicability to quantitative modeling of autogenous shrinkage. The capillary tension approach is advantageous, because it has a sound...... mechanical and thermodynamical basis. Furthermore, this mechanism is easily applicable in a numerical model when dealing with a continuously changing microstructure. In order to test the numerical model, autogenous deformation and internal relative humidity (RH) of a Portland cement paste were measured...... on the capillary tension approach. Because a part of the RH drop in the cement paste is due to dissolved salts in the pore solution, a method is suggested to separate this effect from self-desiccation and to calculate the actual stress in the pore fluid associated with menisci formation....

  19. On the mechanism of high-voltage discharge initiation in high-voltage accelerator accelerating tubes

    Zheleznikov, F.G.

    1983-01-01

    Experimental investigation into physical natupe of discharge processes in high-voltage accelerator accelerating tubes in the absence of the accelerated particle beam are conducted. The installation for the study of the mechanism of initiating vacuum isolation conductivity is used in the experiments. The vacuum chamber of the installation is made of steel and sealed with rubber packings. Electrodes 300-360 mm in diameter are made of stainless steel. Two variants of cleaning technology were used before electrode assembling: 1) degreasing by organic solvents; 2) cleaning by fine grinding cloth with successive washing by rectificated alcohol. Analysis of the obtained data shows that forma. tion of background flux of charged particles in interelectrode gap is caused by external photoelectric effect, excited by X radiation, which initiates the formation of intensive internal field in microfilms of non-conducting impurities on the electrode surfaces. The secondary electron emission plays the minor role at that

  20. Mechanical response of spiral interconnect arrays for highly stretchable electronics

    Qaiser, Nadeem

    2017-11-21

    A spiral interconnect array is a commonly used architecture for stretchable electronics, which accommodates large deformations during stretching. Here, we show the effect of different geometrical morphologies on the deformation behavior of the spiral island network. We use numerical modeling to calculate the stresses and strains in the spiral interconnects under the prescribed displacement of 1000 μm. Our result shows that spiral arm elongation depends on the angular position of that particular spiral in the array. We also introduce the concept of a unit-cell, which fairly replicates the deformation mechanism for full complex hexagon, diamond, and square shaped arrays. The spiral interconnects which are axially connected between displaced and fixed islands attain higher stretchability and thus experience the maximum deformations. We perform tensile testing of 3D printed replica and find that experimental observations corroborate with theoretical study.

  1. Glass-ceramics frits for high mechanical resistance glazes

    Gajek, M.; Lis, J.; Partyka, J.; Wojczyk, M.

    2004-01-01

    The obtaining and application of glass-ceramics frits for glazes were discussed by many authors. This glazes are characterized by raised mechanical parameters and chemical resistance. Factors, that determines crystallization process are initial composition, heat treatment and nucleation agents. The kind of crystalline phases, crystal habit and the content of residual glass phase play the decisive role in the strengthening of the glaze. In this paper are shown results of investigation over controlled crystallization in the ternary systems; Li 2 O-Al 2 O 3 -SiO 2 , CaO-Al 2 O 3 -SiO 2 , ZnO-Al 2 O 3 -SiO 2 , MgO-Al 2 O 3 -SiO 2 , with or without nucleation agents. (author)

  2. Fluid Mechanics of a High Performance Racing Bicycle Wheel

    Mercat, Jean-Pierre; Cretoux, Brieuc; Huat, Francois-Xavier; Nordey, Benoit; Renaud, Maxime; Noca, Flavio

    2013-11-01

    In 2012, MAVIC released the most aerodynamic bicycle wheel on the market, the CXR 80. The french company MAVIC has been a world leader for many decades in the manufacturing of bicycle wheels for competitive events such as the Olympic Games and the Tour de France. Since 2010, MAVIC has been in a research partnership with the University of Applied Sciences in Geneva, Switzerland, for the aerodynamic development of bicycle wheels. While most of the development up to date has been performed in a classical wind tunnel, recent work has been conducted in an unusual setting, a hydrodynamic towing tank, in order to achieve low levels of turbulence and facilitate quantitative flow visualization (PIV). After a short introduction on the aerodynamics of bicycle wheels, preliminary fluid mechanics results based on this novel setup will be presented.

  3. Mechanical response of spiral interconnect arrays for highly stretchable electronics

    Qaiser, Nadeem; Khan, S. M.; Nour, Maha A.; Rehman, M. U.; Rojas, J. P.; Hussain, Muhammad Mustafa

    2017-01-01

    A spiral interconnect array is a commonly used architecture for stretchable electronics, which accommodates large deformations during stretching. Here, we show the effect of different geometrical morphologies on the deformation behavior of the spiral island network. We use numerical modeling to calculate the stresses and strains in the spiral interconnects under the prescribed displacement of 1000 μm. Our result shows that spiral arm elongation depends on the angular position of that particular spiral in the array. We also introduce the concept of a unit-cell, which fairly replicates the deformation mechanism for full complex hexagon, diamond, and square shaped arrays. The spiral interconnects which are axially connected between displaced and fixed islands attain higher stretchability and thus experience the maximum deformations. We perform tensile testing of 3D printed replica and find that experimental observations corroborate with theoretical study.

  4. Mechanism of ruthenium dioxide crystallization during high level waste vitrification

    Boucetta, H.

    2012-01-01

    Ruthenium, arising from the reprocessing of spent uranium oxide fuel, has a low solubility in glass melt. It crystallizes in the form of particles of RuO 2 of acicular or polyhedral morphology dispersed in fission product and actinides waste containment glass. Since the morphology of these particles strongly influences the physico-chemical properties, the knowledge and the control of their mechanism of formation are of major importance. The goal of this work is to determine the chemical reactions responsible for the formation of RuO 2 particles of acicular or polyhedral shape during glass synthesis. Using a simplification approach, the reactions between RuO 2 -NaNO 3 , and more complex calcine RuO 2 -Al 2 O 3 -Na 2 O and a sodium borosilicate glass are studied. In situ scanning electron microscopy and XANES at increasing temperatures are used to follow changes in composition, speciation and morphology of the ruthenium intermediate species. Those compounds are thoroughly characterised by SEM, XRD, HRTEM, and ruthenium K-edge X-ray absorption spectroscopy. This combined approach allows us to show that the ruthenium speciation modification during vitrification is the key of control of the morphology of RuO 2 particles in the glass. In particular, the formation of a specific intermediate compound (Na 3 RuO 4 ) is one of the main steps that lead to the precipitation of needle-shaped RuO 2 particles in the melt. The formation of polyhedral particles, on the contrary, results from the direct incorporation of RuO 2 crystals in the melt followed by an Ostwald ripening mechanism. (author) [fr

  5. Wood Modification at High Temperature and Pressurized Steam: a Relational Model of Mechanical Properties Based on a Neural Network

    Hong Yang

    2015-07-01

    Full Text Available Thermally modified wood has high dimensional stability and biological durability.But if the process parameters of thermal modification are not appropriate, then there will be a decline in the physical properties of wood.A neural network algorithm was employed in this study to establish the relationship between the process parameters of high-temperature and high-pressure thermal modification and the mechanical properties of the wood. Three important parameters: temperature, relative humidity, and treatment time, were considered as the inputs to the neural network. Back propagation (BP neural network and radial basis function (RBF neural network models for prediction were built and compared. The comparison showed that the RBF neural network model had advantages in network structure, convergence speed, and generalization capacity. On this basis, the inverse model, reflecting the relationship between the process parameters and the mechanical properties of wood, was established. Given the desired mechanical properties of the wood, the thermal modification process parameters could be inversely optimized and predicted. The results indicated that the model has good learning ability and generalization capacity. This is of great importance for the theoretical and applicational studies of the thermal modification of wood.

  6. Investigation on the bisoliton mechanism of high-temperature superconductors

    Zhang Lingyun; Li Bozang; Pu Fucho; Lin Jiatih

    1996-01-01

    Microscopic parameters in the Davydov model are calculated on the basis of the bisoliton idea. The energy gap is obtained from combining the condition for the solution of Davydov's equation with the condensation energy of the superconductive state in zero field, and some characteristic parameters of high-temperature superconductors such as coherence length, penetration depth, and density of critical current for a thin film in weak magnetic field are given. It is also proved that lattice displacement in Davydov's equation satisfies the φ 4 field form. The critical temperature and the coefficient of linear specific heat of high-temperature superconductors are studied from the statistics of lattice kinks. The agreement between theoretical and experimental values for YBaCuO oxide ceramics suggests that the bisoliton model gives a reasonable explanation of high-temperature superconductivity. (orig.)

  7. High mechanical Q-factor measurements on silicon bulk material

    Schwarz, Christian; Nawrodt, Ronny; Heinert, Daniel; Schroeter, Anja; Neubert, Ralf; Thuerk, Matthias; Vodel, Wolfgang; Seidel, Paul [Institut fuer Festkoerperphysik, Helmholtzweg 5, D-07743 Jena (Germany); Tuennermann, Andreas [Institut fuer Angewandte Physik, Albert-Einstein-Strasse 15, D-07745 Jena (Germany)

    2008-07-01

    The direct observation of gravitational waves is one of the biggest challenges in science. Current detectors are limited by different kinds of noise. One of the fundamental noise sources is thermal noise arising from the optical components. One of the most promising attempts to reduce the thermal noise contribution in future detectors will be the use of high Q-factor materials at cryogenic temperatures. Silicon seems to be the most interesting material due to its excellent optical and thermal properties. We present high Q-factor measurements on bulk samples of high purity silicon in a temperature range from 5 to 300 K. The sample dimensions vary between 76.2 mm x 12..75 mm. The Q-factor exceeds 4.10{sup 8} at 6 K. The influence of the crystal orientation, doping and the sample preparation on the Q-factor is discussed.

  8. Energy Advantages for Green Schools

    Griffin, J. Tim

    2012-01-01

    Because of many advantages associated with central utility systems, school campuses, from large universities to elementary schools, have used district energy for decades. District energy facilities enable thermal and electric utilities to be generated with greater efficiency and higher system reliability, while requiring fewer maintenance and…

  9. Competitive Intelligence and Social Advantage.

    Davenport, Elisabeth; Cronin, Blaise

    1994-01-01

    Presents an overview of issues concerning civilian competitive intelligence (CI). Topics discussed include competitive advantage in academic and research environments; public domain information and libraries; covert and overt competitive intelligence; data diversity; use of the Internet; cooperative intelligence; and implications for library and…

  10. Improvement of microstructure and mechanical properties of high dense SiC ceramics manufactured by high-speed hot pressing

    Voyevodin, V.; Sayenko, S.; Lobach, K.; Tarasov, R.; Zykova, A.; Svitlychnyi, Ye.; Surkov, A.; Abelentsev, V.; Ghaemi, H.; Szkodo, M.; Gajowiec, G.; Kmiec, M.; Antoszkiewicz, M.

    2017-01-01

    Non-oxide ceramics possess high physical-mechanical properties, corrosion and radiation resistance, which can be used as a protective materials for radioactive wastes disposal. The aim of the present study was the manufacturing of high density SiC ceramics with advanced physical and mechanical parameters. The high performance on the properties of produced ceramics was determined by the dense and monolithic structure. The densified silicon carbide samples possessed good mechanical strength, with a high Vickers micro hardness up to 28.5 GPa.

  11. Mechanical properties of low alloy high phosphorus weathering steel

    Jena B.K.

    2015-01-01

    Full Text Available Mechanical behaviour of two low alloy steels (G11 and G12 was studied with respect to different phosphorus contents. Tensile strength and yield strength increased while percentage elongation at fracture decreased on increasing phosphorus content. The SEM and light optical photomicrograph of low phosphorus steel (G11 revealed ferrite and pearlite microstructure. On increasing phosphorus content from 0.25 wt.% to 0.42 wt.%, the morphology of grain changed from equiaxed shape to pan-cake shape and grain size also increased. The Charpy V notch (CVN impact energy of G11 and G12 steel at room temperature was 32 J and 4 J respectively and their fractographs revealed brittle rupture with cleavage facets for both the steels. However, the fractograph of G11 steel after tensile test exhibited ductile mode of fracture with conical equiaxed dimple while that of G12 steel containing 0.42 wt. % P exhibited transgranular cleavage fracture. Based on this study, G11 steel containing 0.25 wt. % P could be explored as a candidate material for weathering application purpose where the 20°C toughness requirement is 27 J as per CSN EN10025-2:2004 specification.

  12. Aero-Mechanical Coupling in a High-Speed Compressor

    2010-02-01

    freedom mass-spring- damper system as χ = ς 2 √ κµ . (51) ς represents the viscous damping, κ is the system stiffness and µ the system mass. χ expresses...between the fluid and structures which are common in modern, high-speed axial compressors. There were two major areas of focus. The first was the...development of measurement technique specifically for the study of these phenomena, termed Blade Image Velocimetry (BIV). The technique can measure fluid and

  13. Determining the mechanical properties of high porosity nickel

    Frappier, J.C.; Poirier, J.

    1975-01-01

    The following tests were carried out on high porosity (40 to 70%) sintered nickel: tensile tests, compression tests, diametral crushing tests, using strain gauges and extensometers. Results were obtained on the relationship elastic properties - porosity, Poisson coefficient in relation to deformation, variations of yield strength, and breaking stress. these various properties were also studied in relation to the sintering methods and the properties of the powders used [fr

  14. Design of Highly Articulated Mechanism for Surgical Applications

    2016-08-31

    cooperative control of an AGV and snake robot 2. Advanced our filtering estimation theory to handle highly non- linear spaces using Lie algebra tools 3... linear spaces using Lie algebra tools 3. Investigated novel means by which we can infer or sense force at the tip of the snake robot. We have since...most robots, the surgical snake robot is non- linear . We were, however, able to re-write the Kalman filter estimator in the Lie algebra of the position

  15. A Rock Mechanics and Coupled Hydro mechanical Analysis of Geological Repository of High Level Nuclear Waste in Fractured Rocks

    Min, Kibok

    2011-01-01

    This paper introduces a few case studies on fractured hard rock based on geological data from Sweden, Korea is one of a few countries where crystalline rock is the most promising rock formation as a candidate site of geological repository of high level nuclear waste. Despite the progress made in the area of rock mechanics and coupled hydro mechanics, extensive site specific study on multiple candidate sites is essential in order to choose the optimal site. For many countries concerned about the safe isolation of nuclear wastes from the biosphere, disposal in a deep geological formation is considered an attractive option. In geological repository, thermal loading continuously disturbs the repository system in addition to disturbances a recent development in rock mechanics and coupled hydro mechanical study using DFN(Discrete Fracture Network) - DEM(Discrete Element Method) approach mainly applied in hard, crystalline rock containing numerous fracture which are main sources of deformation and groundwater flow

  16. Design of a high speed rotating mechanical shutter

    Stowers, I.F.; Merritt, B.T.; McFann, C.B.

    1979-01-01

    A high-speed rotating shutter was designed to operate in a 10 -6 Torr vacuum at the optical focus of a laser spatial filter. The shutter is basically a wheel, with a single 3 x 10-mm slot at the perimeter, which rotates with a peripheral speed of 1 km/s. The motor to drive the rotating wheel is magnetically suspended and synchronously wound. The wheel achieves a 4 μs opening time and a timing accuracy of better than 0.2 μs

  17. Simultaneously improving the mechanical and electrical properties of poly(vinyl alcohol) composites by high-quality graphitic nanoribbons.

    Yang, Ming; Weng, Lin; Zhu, Hanxing; Zhang, Fan; Fan, Tongxiang; Zhang, Di

    2017-12-07

    Although carbon nanotubes (CNTs) have shown great potential for enhancing the performance of polymer matrices, their reinforcement role still needs to be further improved. Here we implement a structural modification of multi-walled CNTs (MWCNTs) to fully utilize their fascinating mechanical and electrical properties via longitudinal splitting of MWCNTs into graphitic nanoribbons (GNRs). This nanofiller design strategy is advantageous for surface functionalization, strong interface adhesion as well as boosting the interfacial contact area without losing the intrinsic graphitic structure. The obtained GNRs have planar geometry, quasi-1D structure and high-quality crystallinity, which outperforms their tubular counterparts, delivering a superior load-bearing efficiency and conductive network for realizing a synchronous improvement of the mechanical and electrical properties of a PVA-based composite. Compared to PVA/CNTs, the tensile strength, Young's modulus and electrical conductivity of the PVA/GNR composite at a filling concentration of 3.6 vol.% approach 119.1 MPa, 5.3 GPa and 2.4 × 10 -4 S m -1 , with increases of 17%, 32.5% and 5.9 folds, respectively. The correlated mechanics is further rationalized by finite element analysis, the generalized shear-lag theory and the fracture mechanisms.

  18. Mechanical considerations in the processing of high Tc superconductors

    Wright, R.N.; German, R.M.; Knorr, D.B.; Maccrone, R.K.; Rajan, K.

    1990-01-01

    This paper presents a brief review of deformation processing concepts germane to high-Tc superconductor processing, and illustrates some available techniques with results from recent work. It is noted that YBa2Cu3O(7-x) powder/binder cold extrusion technique is quite sensitive to binder formulation and processing conditions. With appropriate technique, indefinite lengths of YBa2Cu3O(7-x) powder/binder composite can be extruded with sufficient workability to allow coiling and other forming operations. With heat treatment, the resulting prototype wire is electrically continuous and manifests critical current densities of a few hundred A/sq cm. The hot extrusion of YBa2Cu3O(7-x) powder results in a modest, but favorable, development of a texture involving preferential rotation of the c-axis toward the radial direction. Billet designs involving larger powder charge diameters, and thinner container walls, produce the favorable texture. Unfortunately, such billet designs reduce workability. 29 refs

  19. Mechanical Design of the NSTX High-k Scattering Diagnostic

    Feder, R.; Mazzucato, E.; Munsat, T.; Park, H.; Smith, D.R.; Ellis, R.; Labik, G.; Priniski, C.

    2005-01-01

    The NSTX High-k Scattering Diagnostic measures small-scale density fluctuations by the heterodyne detection of waves scattered from a millimeter wave probe beam at 280 GHz and λ = 1.07 mm. To enable this measurement, major alterations were made to the NSTX vacuum vessel and Neutral Beam armor. Close collaboration between the PPPL physics and engineering staff resulted in a flexible system with steerable launch and detection optics that can position the scattering volume either near the magnetic axis (ρ ∼ .1) or near the edge (ρ ∼ .8). 150 feet of carefully aligned corrugated waveguide was installed for injection of the probe beam and collection of the scattered signal in to the detection electronics

  20. Thermal-mechanical behavior of high precision composite mirrors

    Kuo, C. P.; Lou, M. C.; Rapp, D.

    1993-01-01

    Composite mirror panels were designed, constructed, analyzed, and tested in the framework of a NASA precision segmented reflector task. The deformations of the reflector surface during the exposure to space enviroments were predicted using a finite element model. The composite mirror panels have graphite-epoxy or graphite-cyanate facesheets, separated by an aluminum or a composite honeycomb core. It is pointed out that in order to carry out detailed modeling of composite mirrors with high accuracy, it is necessary to have temperature dependent properties of the materials involved and the type and magnitude of manufacturing errors and material nonuniformities. The structural modeling and analysis efforts addressed the impact of key design and materials parameters on the performance of mirrors.

  1. Thermal-mechanical behavior of high precision composite mirrors

    Kuo, C.P.; Lou, M.C.; Rapp, D.

    1993-01-01

    Composite mirror panels were designed, constructed, analyzed, and tested in the framework of a NASA precision segmented reflector task. The deformations of the reflector surface during the exposure to space enviroments were predicted using a finite element model. The composite mirror panels have graphite-epoxy or graphite-cyanate facesheets, separated by an aluminum or a composite honeycomb core. It is pointed out that in order to carry out detailed modeling of composite mirrors with high accuracy, it is necessary to have temperature dependent properties of the materials involved and the type and magnitude of manufacturing errors and material nonuniformities. The structural modeling and analysis efforts addressed the impact of key design and materials parameters on the performance of mirrors. 4 refs.

  2. Neoplastic cell transformation by high-LET radiation - Molecular mechanisms

    Yang, Tracy Chui-Hsu; Craise, Laurie M.; Tobias, Cornelius A.; Mei, Man-Tong

    1989-01-01

    Quantitative data were collected on dose-response curves of cultured mouse-embryo cells (C3H10T1/2) irradiated with heavy ions of various charges and energies. Results suggests that two breaks formed on DNA within 80 A may cause cell transformation and that two DNA breaks formed within 20 A may be lethal. From results of experiments with restriction enzymes which produce DNA damages at specific sites, it was found that DNA double strand breaks are important primary lesions for radiogenic cell transformation and that blunt-ended double-strand breaks can form lethal as well as transformational damages due to misrepair or incomplete repair in the cell. The RBE-LET relationship for high-LET radiation is similar to that for HGPRT locus mutation, chromosomal deletion, and cell transformation, indicating that common lesions may be involved in these radiation effects.

  3. Mechanical Design of the NSTX High-k Scattering Diagnostic

    Feder, R.; Mazzucato, E.; Munsat, T.; Park, H,; Smith, D. R.; Ellis, R.; Labik, G.; Priniski, C.

    2005-09-26

    The NSTX High-k Scattering Diagnostic measures small-scale density fluctuations by the heterodyne detection of waves scattered from a millimeter wave probe beam at 280 GHz and {lambda}=1.07 mm. To enable this measurement, major alterations were made to the NSTX vacuum vessel and Neutral Beam armor. Close collaboration between the PPPL physics and engineering staff resulted in a flexible system with steerable launch and detection optics that can position the scattering volume either near the magnetic axis ({rho} {approx} .1) or near the edge ({rho} {approx} .8). 150 feet of carefully aligned corrugated waveguide was installed for injection of the probe beam and collection of the scattered signal in to the detection electronics.

  4. Mechanical characterization of rocks at high strain rate

    Konstantinov A.

    2012-08-01

    Full Text Available The paper presents the dynamic characterization in tension and compression of three rocks, Carrara marble, Onsernone gneiss and Peccia Marble, at high strain-rates. Two versions of a Split Hopkinson Bar have been used. The version for direct tension tests is installed at the DynaMat Laboratory of the University of Applied Sciences of Southern Switzerland, while the traditional version in compression is installed at the Laboratory of Dynamic Investigation of Materials of Lobachevsky State University. Results of the tests show a significantly strain-rate sensitive behaviour, exhibiting dynamic strength increasing with strain-rate. The experimental research has been developed in the frame of the Swiss-Russian Joint Research Program.

  5. Mechanism of death at high temperatures in Helix and Patella

    Grainger, J N.R.

    1975-10-01

    In Patella vulgata and Helix aspersa which had been killed by exposure to high temperatures, the rates of oxygen consumption of gill, foot muscle and hepatopancreas are remarkably steady when measured at lower temperatures, although the absolute levels are in some cases different from normal animals. These tissues are thus substantially metabolically intact in heat dead individuals. In Helix there is a fall in blood sodium and a rise in blood potassium during heat death. In Patella there is a marked rise in blood Na/sup +/ and a consequent disturbance of the Na/sup +//K/sup +/ ratio. These ionic disturbances are thought to be a prime cause of heat death. The significance of the results is discussed.

  6. Statistical mechanics of complex neural systems and high dimensional data

    Advani, Madhu; Lahiri, Subhaneil; Ganguli, Surya

    2013-01-01

    Recent experimental advances in neuroscience have opened new vistas into the immense complexity of neuronal networks. This proliferation of data challenges us on two parallel fronts. First, how can we form adequate theoretical frameworks for understanding how dynamical network processes cooperate across widely disparate spatiotemporal scales to solve important computational problems? Second, how can we extract meaningful models of neuronal systems from high dimensional datasets? To aid in these challenges, we give a pedagogical review of a collection of ideas and theoretical methods arising at the intersection of statistical physics, computer science and neurobiology. We introduce the interrelated replica and cavity methods, which originated in statistical physics as powerful ways to quantitatively analyze large highly heterogeneous systems of many interacting degrees of freedom. We also introduce the closely related notion of message passing in graphical models, which originated in computer science as a distributed algorithm capable of solving large inference and optimization problems involving many coupled variables. We then show how both the statistical physics and computer science perspectives can be applied in a wide diversity of contexts to problems arising in theoretical neuroscience and data analysis. Along the way we discuss spin glasses, learning theory, illusions of structure in noise, random matrices, dimensionality reduction and compressed sensing, all within the unified formalism of the replica method. Moreover, we review recent conceptual connections between message passing in graphical models, and neural computation and learning. Overall, these ideas illustrate how statistical physics and computer science might provide a lens through which we can uncover emergent computational functions buried deep within the dynamical complexities of neuronal networks. (paper)

  7. Advertising Dynamics and Competitive Advantage

    Ulrich Doraszelski; Sarit Markovich

    2004-01-01

    Can advertising lead to a sustainable competitive advantage? To answer this question, we propose a dynamic model of advertising competition where firms repeatedly advertise, compete in the product market, and make entry as well as exit decisions. Within this dynamic framework, we study two different models of advertising: In the first model, advertising influences the goodwill consumers extend towards a firm ("goodwill advertising"), whereas in the second model it influences the share of cons...

  8. Interest alignment and competitive advantage

    Gottschalg, Oliver; Zollo, Mauricio

    2006-01-01

    This paper articulates a theory of the conditions under which the alignment between individual and collective interests generates sustainable competitive advantage. The theory is based on the influence of tacitness, context-specificity and casual ambiguity in the determinants of different types of motivation (extrinsic, normative intrinsic and hedonic intrinsic), under varying conditions of environmental dynamism. The analysis indicates the need to consider mitivational processes as a complem...

  9. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    Tawancy, H.M.; Aboelfotoh, M.O.

    2014-01-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt 2 Mo-type, DO 22 and D1 a superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420} fcc planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt 2 Mo-type and DO 22 superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1 a superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries

  10. Characterization and Conduction Mechanism of Highly Conductive Vanadate Glass

    Tetsuaki Nishida

    2015-12-01

    Full Text Available This paper reviews recent studies of highly conductive barium iron vanadate glass with a composition of 20 BaO ∙ 10 Fe2O3 ∙ 70 V2O5 (in mol %. Isothermal annealing of the vanadate glass for several ten minutes at a given temperature, higher than glass transition temperature or crystallization temperature, caused an increase in σ. Substitution of CuI (3d10, ZnII (3d10 and CuII (3d9 for FeIII (3d5 was investigated to elucidate the effect of electron configuration on the conductivity (σ. A marked decrease in the activation energy of conduction (Ea was also observed after the annealing. Values of Ea were correlated to the energy gap between the donor level and the conduction band (CB in the n-type semiconductor model. Isothermal annealing of ZnII-substituted vanadate glass (20 BaO ∙ 5 ZnO ∙ 5 Fe2O3 ∙ 70 V2O5 at 450 °C for 30 min showed an increase in σ from 2.5 × 10–6 to 2.1 × 10–1 S cm–1, which was one order of magnitude larger than that of non-substituted vanadate glass (3.4 × 10–2 S cm–1. Under the same annealing condition, σ’s of 2.0 × 10–1 and 3.2 × 10–1 S cm–1 were observed for 20 BaO ∙ 5 Cu2O ∙ 5 Fe2O3 ∙ 70 V2O5 and 20 BaO ∙ 5 CuO ∙ 5 Fe2O3 ∙ 70 V2O5 glasses, respectively. These results demonstrate an increase in the carrier (electron density in the CB, primarily composed of anti-bonding 4s-orbitals.

  11. COMPETITORS ACCOUNTING AS A COMPETITIVE ADVANTAGE TOOL

    YÜCENURŞEN, Mehmet; DUMAN, Haluk; APAK, İbrahim; KALAV, Ömer

    2016-01-01

    In recent years, it seems that businesses adopt customer-oriented marketing strategies. According to the adopted strategies to keep customer satisfaction at the highest level, businesses have been focused to developt new product, to find new customers, to improve distribution and promotion activity etc. Besides, businesses have recognized that they should analize their competitor’s activity and movement to make high profit and growth. Porter's competitive advantage that it is possib...

  12. Finance, Comparative Advantage, and Resource Allocation

    Jaud, Melise; Kukenova, Madina; Strieborny, Martin

    2013-01-01

    The authors show that exported products exit the US market sooner if they violate the Heckscher-Ohlin notion of comparative advantage. Crucially, this pattern is stronger when exporting country has a well-developed banking system, measured by a high ratio of bank credit over the GDP. Banks thus push firms away from exports that are facing an uphill battle on a competitive foreign market du...

  13. BUSINESS COMPETITORS AND COMPETITIVE ADVANTAGE

    SUCIU TITUS

    2013-08-01

    Full Text Available The paper presents the concept of competition, both from the perspective of the economic sector –where it is characteristic for pure monopole, oligopoly, monopole competition and pure competition, as well asfrom the market’s point of view – where it determines the strategies, objectives, advantages and weaknesses of acompany. The main point of the paper is the criticism of the pure and perfect competition theory. Concluding,the author insists on innovation, especially on the model of open innovation.

  14. Ecology. The advantages of togetherness.

    Cox, E; Bonner, J

    2001-04-20

    What would be the advantage of unicellular organisms becoming multicellular? For organisms that feed on organic food (heterotrophs), the most efficient way to produce energy is to metabolize the food by aerobic respiration, but the fastest way is to metabolize it by fermentation. In their Perspective, Cox and Bonner discuss a mathematical model (Pfeiffer et al.), which shows that when these two kinds of organisms (respirators and fermenters) compete for a limited food source, the respirators manage best when they are grouped in clusters rather than remaining as separate cells. In this way, multicellularity could have originated.

  15. Advantages of computed tomographic guidance

    Casola, G.; Vansonnenberg, E.

    1987-01-01

    Both ultrasound and CT are successfully used to guide interventional procedures throughout the body. There are advantages and disadvantages to each modality and choosing one over the other will vary from case to case. Major factors influencing choice are discussed in this paper. As a general rule CT guidance is usually required for lesions in the thorax, the adrenals, the pancreas, lymph nodes, and for percutaneous abscess drainage. The authors feel that a complimentary use of ultrasound and CT is essential to optimize success and cost-effectiveness; therefore, the interventional radiologist should be familiar with both imaging modalities

  16. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    Tawancy, H.M., E-mail: tawancy@kfupm.edu.sa [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, KFUPM Box 1639, Dhahran 31261 (Saudi Arabia); Aboelfotoh, M.O., E-mail: oaboelfotoh@gmail.com [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27606 (United States)

    2014-05-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt{sub 2}Mo-type, DO{sub 22} and D1{sub a} superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420}{sub fcc} planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt{sub 2}Mo-type and DO{sub 22} superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1{sub a} superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries.

  17. Contextual Advantage for State Discrimination

    Schmid, David; Spekkens, Robert W.

    2018-02-01

    Finding quantitative aspects of quantum phenomena which cannot be explained by any classical model has foundational importance for understanding the boundary between classical and quantum theory. It also has practical significance for identifying information processing tasks for which those phenomena provide a quantum advantage. Using the framework of generalized noncontextuality as our notion of classicality, we find one such nonclassical feature within the phenomenology of quantum minimum-error state discrimination. Namely, we identify quantitative limits on the success probability for minimum-error state discrimination in any experiment described by a noncontextual ontological model. These constraints constitute noncontextuality inequalities that are violated by quantum theory, and this violation implies a quantum advantage for state discrimination relative to noncontextual models. Furthermore, our noncontextuality inequalities are robust to noise and are operationally formulated, so that any experimental violation of the inequalities is a witness of contextuality, independently of the validity of quantum theory. Along the way, we introduce new methods for analyzing noncontextuality scenarios and demonstrate a tight connection between our minimum-error state discrimination scenario and a Bell scenario.

  18. Contextual Advantage for State Discrimination

    David Schmid

    2018-02-01

    Full Text Available Finding quantitative aspects of quantum phenomena which cannot be explained by any classical model has foundational importance for understanding the boundary between classical and quantum theory. It also has practical significance for identifying information processing tasks for which those phenomena provide a quantum advantage. Using the framework of generalized noncontextuality as our notion of classicality, we find one such nonclassical feature within the phenomenology of quantum minimum-error state discrimination. Namely, we identify quantitative limits on the success probability for minimum-error state discrimination in any experiment described by a noncontextual ontological model. These constraints constitute noncontextuality inequalities that are violated by quantum theory, and this violation implies a quantum advantage for state discrimination relative to noncontextual models. Furthermore, our noncontextuality inequalities are robust to noise and are operationally formulated, so that any experimental violation of the inequalities is a witness of contextuality, independently of the validity of quantum theory. Along the way, we introduce new methods for analyzing noncontextuality scenarios and demonstrate a tight connection between our minimum-error state discrimination scenario and a Bell scenario.

  19. Salvador Dalí's paintings to introduce Quantum Mechanics concepts in High School

    Rúbia de Fátima Antunes Martins Fernandes; Flaviston Ferreira Pires; Thaís Cyrino de Mello Forato; José Alves da Silva

    2017-01-01

    A few papers have presented results of teaching Quantum Mechanics in High School. As a high abstraction level is demanded, it is necessary to reconsider theoretical assumptions, approaches and methodologies, in order to reduce difficulties in its insertion. This paper presents the achievements of a research, which is a didactic proposal for High School comprising discussions about Quantum Mechanics, involving elements that relate Physics and some paintings of Salvador Dalí. Embracing the rela...

  20. Strengthening mechanisms and mechanical properties of high interstitial stainless steel for drill collar and its corrosion resistance

    Lee, Eunkyung

    Two types (CN66, CN71) of high interstitial stainless steels (HISSs) were investigated for down-hole application in sour gas well environments. Experiments were designed to identify factors that have a significant effect on mechanical properties. The three factors examined in the study were carbon + nitrogen content (0.66 or 0.71 mass %), cooling rate in quenching (air or water), and heat treatment time (2 or 4 hours). The results showed that the cooling rate, C+N content, and the two-factor interaction of these variables have a significant effect on the mechanical properties of HISSs. Based on the statistical analysis results on mechanical properties, extensive analyses were undertaken to understand the strengthening mechanisms of HISSs. Microstructure analysis revealed that a pearlite phase with a high carbide and/or nitride content is dissolved in the matrix by heat treatment at 1,200 ºC which is considered the dissolution to increase the concentration of interstitial elements in steels. The distribution of elements in HISSs was investigated by quantitative mapping using EPMA, which showed that the high carbon concentration (carbide/cementite) area was decreased by increases in both the cooling rate and C+N content. The ferrite volume fraction of each specimen is increased by an increase in cooling rate, because there is insufficient time to form austenite from retained ferrite. The lattice expansion of HISS was investigated by the calculation of lattice parameters under various conditions, and these investigations confirm the solid solution strengthening effect on HISSs. CN66 with heat treatment at fast cooling has the highest wear resistance; a finding that was consistent with hardening mechanisms that occur due to an increased ferrite volume fraction. In addition, precipitates on the surface and the chemical bonding of chromium were investigated. As the amount of CrN bonding increased, the wear resistance also increased. This study also assessed the

  1. [Internet research methods: advantages and challenges].

    Liu, Yi; Tien, Yueh-Hsuan

    2009-12-01

    Compared to traditional research methods, using the Internet to conduct research offers a number of advantages to the researcher, which include increased access to sensitive issues and vulnerable / hidden populations; decreased data entry time requirements; and enhanced data accuracy. However, Internet research also presents certain challenges to the researcher. In this article, the advantages and challenges of Internet research methods are discussed in four principle issue areas: (a) recruitment, (b) data quality, (c) practicality, and (d) ethics. Nursing researchers can overcome problems related to sampling bias and data truthfulness using creative methods; resolve technical problems through collaboration with other disciplines; and protect participant's privacy, confidentiality and data security by maintaining a high level of vigilance. Once such issues have been satisfactorily addressed, the Internet should open a new window for Taiwan nursing research.

  2. Sustainable competitive advantage for accountable care organizations.

    Macfarlane, Michael Alex

    2014-01-01

    In the current period of health industry reform, accountable care organizations (ACOs) have emerged as a new model for the delivery of high-quality and cost-effective healthcare. However, few ACOs operate in direct competition with one another, and the accountable care business model has yet to present a means of continually developing new marginal value for patients and network partners. With value-based purchasing and patient consumerism strengthening as market forces, ACOs must build organizational sustainability and competitive advantage to meet the value demands set by customers and competitors. This essay proposes a strategy, adapted from the disciplines of agile software development and Lean product development, through which ACOs can engage internal and external customers in the development of new products that will provide sustainability and competitive advantage to the organization by decreasing waste in development, promoting specialized knowledge, and closely targeting customer value.

  3. Parenting Advantage in the MNC

    Nell, Phillip C.; Ambos, Björn

    2013-01-01

    subsidiaries located in Europe. Our results indicate that the external embeddedness of the MNC is an antecedent to headquarters' value creation. We find that headquarters' investments into their own relationships with the subsidiaries' contexts are positively related to the value added by headquarters....... Furthermore, this relationship is stronger when the subsidiary itself is strongly embedded. We discuss implications for the MNC literature, embeddedness research, and the literature on parenting and headquarters' roles......What determines the value an MNC's headquarters adds to its own affiliates? In this paper, we shed light on this question by linking the embeddedness view of the multinational corporation to the literature on parenting advantage. We test our hypotheses on an original dataset of 124 manufacturing...

  4. Nuclear energy. Risk or advantage

    Boettiger, Helmut

    2011-01-01

    Nuclear energy is controversial. But what's all about really in the controversy? It's about more than safty or electricity prices. Nuclear energy is not only a technical or political question, but also a moral, a human. The discussion enter various rational and irrational arguments, beside straightforward arguments various misleading and mendacious exist. The present publication is comprehensively dedicated to the thema of nuclear energy - its pro and contra - and considers its risks and advantages. Thereby the sources of energy, the processes in the nuclear reactor, and the risk potentials (Harrisburg, Chernobyl, Fukushima) are illustratively and reproducibly presented. Extensively the text explains the forms of the radiation, its doses, and the tolerance of it. Also to the theme waste and final disposal an explaining chapter is dedicated and the question for the exit from nuclear energy elucidated. Finally the author appoints with the question ''How considers mankind nuclear energy world-wide'' the international comparison.

  5. Marketing channels and competitive advantage

    Jovičić Dragoljub

    2005-01-01

    Full Text Available Issue that can already be seen and will be very clear in the future is that the central problem in the market of tube caps will not be the product or the price or promotion, but marketing channels. Therefore, the competitive advantage will most probably be built on marketing channels and not the production - as it has been so far, so, the questions of choice functioning and modification of marketing channels, as well as selection of the most appropriate members of channels will become more and more important. Accordingly, it may freely be said that the choice, i.e. the movement of marketing channels represents one of the strategic decisions which has to be made by a company management and which will subsequently very significantly influence the functioning and efficacy of not only the system of distribution, but also the entire business transactions.

  6. Advantages of Oscillatory Hydraulic Tomography

    Kitanidis, P. K.; Bakhos, T.; Cardiff, M. A.; Barrash, W.

    2012-12-01

    Characterizing the subsurface is significant for most hydrogeologic studies, such as those involving site remediation and groundwater resource explo¬ration. A variety of hydraulic and geophysical methods have been developed to estimate hydraulic conductivity and specific storage. Hydraulic methods based on the analysis of conventional pumping tests allow the estimation of conductivity and storage without need for approximate petrophysical relations, which is an advantage over most geophysical methods that first estimate other properties and then infer values of hydraulic parameters. However, hydraulic methods have the disadvantage that the head-change signal decays with distance from the pumping well and thus becomes difficult to separate from noise except in close proximity to the source. Oscillatory hydraulic tomography (OHT) is an emerging technology to im¬age the subsurface. This method utilizes the idea of imposing sinusoidally varying pressure or discharge signals at several points, collecting head observations at several other points, and then processing these data in a tomographic fashion to estimate conductivity and storage coefficients. After an overview of the methodology, including a description of the most important potential advantages and challenges associated with this approach, two key promising features of the approach will be discussed. First, the signal at an observation point is orthogonal to and thus can be separated from nuisance inputs like head fluctuation from production wells, evapotranspiration, irrigation, and changes in the level of adjacent streams. Second, although the signal amplitude may be weak, one can extract the phase and amplitude of the os¬cillatory signal by collecting measurements over a longer time, thus compensating for the effect of large distance through longer sampling period.

  7. Aero-Mechanical Design Methodology for Subsonic Civil Transport High-Lift Systems

    vanDam, C. P.; Shaw, S. G.; VanderKam, J. C.; Brodeur, R. R.; Rudolph, P. K. C.; Kinney, D.

    2000-01-01

    In today's highly competitive and economically driven commercial aviation market, the trend is to make aircraft systems simpler and to shorten their design cycle which reduces recurring, non-recurring and operating costs. One such system is the high-lift system. A methodology has been developed which merges aerodynamic data with kinematic analysis of the trailing-edge flap mechanism with minimum mechanism definition required. This methodology provides quick and accurate aerodynamic performance prediction for a given flap deployment mechanism early on in the high-lift system preliminary design stage. Sample analysis results for four different deployment mechanisms are presented as well as descriptions of the aerodynamic and mechanism data required for evaluation. Extensions to interactive design capabilities are also discussed.

  8. A mathematical high bar-human body model for analysing and interpreting mechanical-energetic processes on the high bar.

    Arampatzis, A; Brüggemann, G P

    1998-12-01

    The aims of this study were: 1. To study the transfer of energy between the high bar and the gymnast. 2. To develop criteria from the utilisation of high bar elasticity and the utilisation of muscle capacity to assess the effectiveness of a movement solution. 3. To study the influence of varying segment movement upon release parameters. For these purposes a model of the human body attached to the high bar (high bar-human body model) was developed. The human body was modelled using a 15-segment body system. The joint-beam element method (superelement) was employed for modelling the high bar. A superelement consists of four rigid segments connected by joints (two Cardan joints and one rotational-translational joint) and springs (seven rotation springs and one tension-compression spring). The high bar was modelled using three superelements. The input data required for the high bar human body model were collected with video-kinematographic (50 Hz) and dynamometric (500 Hz) techniques. Masses and moments of inertia of the 15 segments were calculated using the data from the Zatsiorsky et al. (1984) model. There are two major phases characteristic of the giant swing prior to dismounts from the high bar. In the first phase the gymnast attempts to supply energy to the high bar-humanbody system through muscle activity and to store this energy in the high bar. The difference between the energy transferred to the high bar and the reduction in the total energy of the body could be adopted as a criterion for the utilisation of high bar elasticity. The energy previously transferred into the high bar is returned to the body during the second phase. An advantageous increase in total body energy at the end of the exercise could only be obtained through muscle energy supply. An index characterising the utilisation of muscle capacity was developed out of the difference between the increase in total body energy and the energy returned from the high bar. A delayed and initially slow but

  9. Using IT-CMF to build Competitive Advantage

    McLaughlin, Stephen

    2012-01-01

    Developing a competitive advantage, for any organization, is a key business imperative. Without some form of competitive advantage it is very difficult to compete within today’s highly dynamic market place. In order to develop competitive advantages organizations must focus on identifying and building their core capabilities. As technology’s influence is now pervasive throughout every aspect of organizational life organizations must consider the role their IT based ...

  10. Microstructure and Mechanical Properties of High Copper HSLA-100 Steel in 2-inch Plate Form

    1992-06-01

    CCT diagram . Increasing copper in HSLA-100 steel also increases the toughness as well as the strength, though the dynamics of this process are not clear. Steel, High Copper HSLA-100 Steel, mechanical property, microstructure.

  11. Review of important rock mechanics studies required for underground high level nuclear waste repository program

    Kwon, S.; Cho, W. J

    2007-01-15

    Disposal concept adapting room and pillar method, which is a confirmed technique in mining and tunnel construction for long time, has advantages at cost, safety, technical feasibility, flexibility, and international cooperation point of views. Then the important rock mechanics principals and in situ and laboratory tests for understanding the behavior of rock, buffer, and backfill as well as their interactions will be reviewed. The accurate understanding of them is important for developing a safe disposal concept and successful operation of underground repository for permanent disposal of radioactive wastes. First of all, In this study, current status of rock mechanics studies for HLW disposal in foreign countries such as Sweden, USA, Canada, Finland, Japan, and France were reviewed. After then the in situ and laboratory tests for site characterization were summarized. Furthermore, rock mechanics studies required during the whole procedure for the disposal project from repository design to the final closure will be reviewed systematically. This study will help for developing a disposal system including site selection, repository design, operation, maintenance, and closure of a repository in deep underground rock. By introducing the required rock mechanics tests at different stages, it would be helpful from the planning stage to the operation stage of a radioactive waste disposal project.

  12. Review of important rock mechanics studies required for underground high level nuclear waste repository program

    Kwon, S.; Cho, W. J.

    2007-01-01

    Disposal concept adapting room and pillar method, which is a confirmed technique in mining and tunnel construction for long time, has advantages at cost, safety, technical feasibility, flexibility, and international cooperation point of views. Then the important rock mechanics principals and in situ and laboratory tests for understanding the behavior of rock, buffer, and backfill as well as their interactions will be reviewed. The accurate understanding of them is important for developing a safe disposal concept and successful operation of underground repository for permanent disposal of radioactive wastes. First of all, In this study, current status of rock mechanics studies for HLW disposal in foreign countries such as Sweden, USA, Canada, Finland, Japan, and France were reviewed. After then the in situ and laboratory tests for site characterization were summarized. Furthermore, rock mechanics studies required during the whole procedure for the disposal project from repository design to the final closure will be reviewed systematically. This study will help for developing a disposal system including site selection, repository design, operation, maintenance, and closure of a repository in deep underground rock. By introducing the required rock mechanics tests at different stages, it would be helpful from the planning stage to the operation stage of a radioactive waste disposal project

  13. Autogenous shrinkage in high-performance cement paste: An evaluation of basic mechanisms

    Lura, Pietro; Jensen, Ole Mejlhede; Breugel, Klaas van

    2003-01-01

    In this paper, various mechanisms suggested to cause autogenous shrinkage are presented. The mechanisms are evaluated from the point of view of their soundness and applicability to quantitative modeling of autogenous shrinkage. The capillary tension approach is advantageous, because it has a sound mechanical and thermodynamical basis. Furthermore, this mechanism is easily applicable in a numerical model when dealing with a continuously changing microstructure. In order to test the numerical model, autogenous deformation and internal relative humidity (RH) of a Portland cement paste were measured during the first week of hardening. The isothermal heat evolution was also recorded to monitor the progress of hydration and the elastic modulus in compression was measured. RH change, degree of hydration and elastic modulus were used as input data for the calculation of autogenous deformation based on the capillary tension approach. Because a part of the RH drop in the cement paste is due to dissolved salts in the pore solution, a method is suggested to separate this effect from self-desiccation and to calculate the actual stress in the pore fluid associated with menisci formation

  14. Explaining Asian Americans’ academic advantage over whites

    Hsin, Amy; Xie, Yu

    2014-01-01

    The superior academic achievement of Asian Americans is a well-documented phenomenon that lacks a widely accepted explanation. Asian Americans’ advantage in this respect has been attributed to three groups of factors: (i) socio-demographic characteristics, (ii) cognitive ability, and (iii) academic effort as measured by characteristics such as attentiveness and work ethic. We combine data from two nationally representative cohort longitudinal surveys to compare Asian-American and white students in their educational trajectories from kindergarten through high school. We find that the Asian-American educational advantage is attributable mainly to Asian students exerting greater academic effort and not to advantages in tested cognitive abilities or socio-demographics. We test explanations for the Asian–white gap in academic effort and find that the gap can be further attributed to (i) cultural differences in beliefs regarding the connection between effort and achievement and (ii) immigration status. Finally, we highlight the potential psychological and social costs associated with Asian-American achievement success. PMID:24799702

  15. Explaining Asian Americans' academic advantage over whites.

    Hsin, Amy; Xie, Yu

    2014-06-10

    The superior academic achievement of Asian Americans is a well-documented phenomenon that lacks a widely accepted explanation. Asian Americans' advantage in this respect has been attributed to three groups of factors: (i) socio-demographic characteristics, (ii) cognitive ability, and (iii) academic effort as measured by characteristics such as attentiveness and work ethic. We combine data from two nationally representative cohort longitudinal surveys to compare Asian-American and white students in their educational trajectories from kindergarten through high school. We find that the Asian-American educational advantage is attributable mainly to Asian students exerting greater academic effort and not to advantages in tested cognitive abilities or socio-demographics. We test explanations for the Asian-white gap in academic effort and find that the gap can be further attributed to (i) cultural differences in beliefs regarding the connection between effort and achievement and (ii) immigration status. Finally, we highlight the potential psychological and social costs associated with Asian-American achievement success.

  16. Effect of high pressure on the mechanical properties of lithium disilicate glass ceramic

    Buchner, Silvio; Lepienski, Carlos M.; Jr, Paulo C. Soares; Balzaretti, Naira M.

    2011-01-01

    Research highlights: → High pressure densification of LS2 decreases the mechanical properties. → Densification of LS2 at high temperature improves the mechanical properties. → Hardness and elastic modulus of LS2 densified at high temperature are notably high. - Abstract: Lithium disilicate glass has been submitted to a high pressure treatment associated to a heat treatment, and the effects of densification and crystallization at high pressure on the mechanical properties were evaluated. The hardness and elastic modulus were examined by instrumented indentation using a Berkovich tip. The crack pattern morphology after indentation with a cube corner indenter was also investigated. The hardness and elastic modulus of the samples submitted to high pressure at room temperature decreased with increasing pressure. The hardness and elastic modulus of the samples submitted simultaneously to high pressure (up to 7.7 GPa) and high temperature increased noticeably. The amount, length and type of cracks induced by the cube corner tip changed with increasing pressure. These results indicate that the high temperature treatment under high pressure improved the mechanical properties of LS 2 .

  17. Mechanics

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  18. Invited review article: high-speed flexure-guided nanopositioning: mechanical design and control issues.

    Yong, Y K; Moheimani, S O R; Kenton, B J; Leang, K K

    2012-12-01

    Recent interest in high-speed scanning probe microscopy for high-throughput applications including video-rate atomic force microscopy and probe-based nanofabrication has sparked attention on the development of high-bandwidth flexure-guided nanopositioning systems (nanopositioners). Such nanopositioners are designed to move samples with sub-nanometer resolution with positioning bandwidth in the kilohertz range. State-of-the-art designs incorporate uniquely designed flexure mechanisms driven by compact and stiff piezoelectric actuators. This paper surveys key advances in mechanical design and control of dynamic effects and nonlinearities, in the context of high-speed nanopositioning. Future challenges and research topics are also discussed.

  19. Evolutionary advantages of adaptive rewarding

    Szolnoki, Attila; Perc, Matjaž

    2012-01-01

    Our well-being depends on both our personal success and the success of our society. The realization of this fact makes cooperation an essential trait. Experiments have shown that rewards can elevate our readiness to cooperate, but since giving a reward inevitably entails paying a cost for it, the emergence and stability of such behavior remains elusive. Here we show that allowing for the act of rewarding to self-organize in dependence on the success of cooperation creates several evolutionary advantages that instill new ways through which collaborative efforts are promoted. Ranging from indirect territorial battle to the spontaneous emergence and destruction of coexistence, phase diagrams and the underlying spatial patterns reveal fascinatingly rich social dynamics that explain why this costly behavior has evolved and persevered. Comparisons with adaptive punishment, however, uncover an Achilles heel of adaptive rewarding, coming from over-aggression, which in turn hinders optimal utilization of network reciprocity. This may explain why, despite its success, rewarding is not as firmly embedded into our societal organization as punishment. (paper)

  20. Experimental study and modelling of the high temperature mechanical behavior of oxide dispersion strengthened ferritic steels

    Steckmeyer, A.

    2012-01-01

    The strength of metals, and therefore their maximum operating temperature, can be improved by oxide dispersion strengthening (ODS). Numerous research studies are carried out at the French Atomic Energy Commission (CEA) in order to develop a cladding tube material for Gen IV nuclear power reactors. Oxide dispersion strengthened steels appear to be the most promising candidates for such application, which demands a minimum operating temperature of 650 C. The present dissertation intends to improve the understanding of the mechanical properties of ODS steels, in terms of creep lifetime and mechanical anisotropy. The methodology of this work includes mechanical tests between room temperature and 900 C as well as macroscopic and polycrystalline modelling. These tests are carried out on a Fe-14Cr1W0,26Ti + 0,3 Y 2 O 3 ODS ferritic steel processed at CEA by mechanical alloying and hot extrusion. The as-received material is a bar with a circular section. The mechanical tests reveal the high mechanical strength of this steel at high temperature. A strong influence of the strain rate on the ductility and the mechanical strength is also observed. A macroscopic mechanical model has been developed on the basis of some experimental statements such as the high kinematic contribution to the flow stress. This model has a strong ability to reproduce the mechanical behaviour of the studied material. Two different polycrystalline models have also been developed in order to reproduce the mechanical anisotropy of the material. They are based on its specific grain morphology and crystallographic texture. The discrepancy between the predictions of both models and experimental results reveal the necessity to formulate alternate assumptions on the deformation mechanisms of ODS ferritic steels. (author) [fr

  1. Advantages of semiconductor CZT for medical imaging

    Wagenaar, Douglas J.; Parnham, Kevin; Sundal, Bjorn; Maehlum, Gunnar; Chowdhury, Samir; Meier, Dirk; Vandehei, Thor; Szawlowski, Marek; Patt, Bradley E.

    2007-09-01

    Cadmium zinc telluride (CdZnTe, or CZT) is a room-temperature semiconductor radiation detector that has been developed in recent years for a variety of applications. CZT has been investigated for many potential uses in medical imaging, especially in the field of single photon emission computed tomography (SPECT). CZT can also be used in positron emission tomography (PET) as well as photon-counting and integration-mode x-ray radiography and computed tomography (CT). The principal advantages of CZT are 1) direct conversion of x-ray or gamma-ray energy into electron-hole pairs; 2) energy resolution; 3) high spatial resolution and hence high space-bandwidth product; 4) room temperature operation, stable performance, high density, and small volume; 5) depth-of-interaction (DOI) available through signal processing. These advantages will be described in detail with examples from our own CZT systems. The ability to operate at room temperature, combined with DOI and very small pixels, make the use of multiple, stationary CZT "mini-gamma cameras" a realistic alternative to today's large Anger-type cameras that require motion to obtain tomographic sampling. The compatibility of CZT with Magnetic Resonance Imaging (MRI)-fields is demonstrated for a new type of multi-modality medical imaging, namely SPECT/MRI. For pre-clinical (i.e., laboratory animal) imaging, the advantages of CZT lie in spatial and energy resolution, small volume, automated quality control, and the potential for DOI for parallax removal in pinhole imaging. For clinical imaging, the imaging of radiographically dense breasts with CZT enables scatter rejection and hence improved contrast. Examples of clinical breast images with a dual-head CZT system are shown.

  2. Operational report, Advantages of gradual introducing of highly enriched fuel into the RA reactor core from economic aspect and users needs; Radni izvestaj, Prednost postupka parcijalnog uvodjenja visokoobogacenog goriva u reaktor RA sa aspekta ekonomicnosti i potreba korisnika

    Martinc, R et al. [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

    1976-10-14

    The possibility of increasing the neutron flux in the RA reactor was considered for a number of years. The possibilities of reactor reconstruction are not realistic and they should be disregarded. The possibility that remains is to achieve higher neutron flux by improving the fueling scheme and above all by introducing highly enriched fuel into the reactor core. Decision to purchase highly enriched fuel was quicker due to the fact that the 2% enriched uranium fuel is not fabricated any more. There are two procedures for exchanging the fuel in the reactor core: a) removal of partially spent 2% enriched fuel and formation of the core with fresh highly enriched fuel; b) gradually introducing the new fuel into the existing RA reactor core according to a special transfer regime. This report includes some comparative analyses of these two procedures from both economic point of view and the needs of users, as well as some technical conditions. These results are in favour of gradual introducing of new fuel into the reactor core. relevant direct savings amount to 3 000 000 dinars. Some of the most important advantages cannot be estimated in this way. This report does not cover the safety analyses results which are presented in a series of other papers. [Serbo-Croat] Vec vise godina razmatra se mogucnost za povecanje neutronskog fluksa u reaktoru RA. Mogucnosti za rekonstrukciju reaktora RA u tom smislu su minimalne i realno ih treba odbaciti. Prema tome preostaje da se povecanje neutronskog fluksa postigne usavrsavanjem seme izmene goriva, a pre svega uvodjenjem goriva sa visokim stepenom obogacenja u reaktor RA. Donosenje odluke o nabavci visokoobogacenog goriva i njegovom uvodjenju u reaktor ubrzano je i cinjenicom da se staro 2% obogaceno uransko gorivo vise ne proizvodi. Postoje dva postupka za prevodjenje reaktora na ovo gorivo: a) Uklanjanjem poluistrosenog 2% obogacenog goriva iz reaktora i formiranjem jezgra iskljucivo od svezeg visokoobogacenog goriva, b

  3. Influence of niobium addition on the high temperature mechanical properties of a centrifugally cast HP alloy

    Andrade, A.R.; Bolfarini, C.; Ferreira, L.A.M.; Vilar, A.A.A.; Souza Filho, C.D.; Bonazzi, L.H.C.

    2015-01-01

    The influence of niobium addition on the mechanical properties at high temperature of HP alloy has been investigated. Two HP alloys were centrifugally cast with a similar chemical composition differing only in the niobium content. Low strain rate high temperature tensile tests and creep-rupture tests were performed in the range of 900–1100 °C, and the results compared between the alloys. According to the results, the high temperature mechanical behavior of both alloys is controlled by several factors like solid solution, network of eutectic carbides, intradendritic precipitation and dendrite spacing. A significant increase in the mechanical properties for the HP alloy with niobium addition was found within the temperature range of 900–1050 °C. Beyond this temperature the mechanical behavior of both alloys is basically the same

  4. The high density and high βpol disruption mechanism on TFTR

    Fredrickson, E.D.; Manickam, J.; McGuire, K.M.; Monticello, D.; Nagayama, Y.; Park, W.; Taylor, G.

    1992-01-01

    Studies of disruptions on TFTR have been extended to include high density disruptions as well as the high β pol disruptions. The data strongly suggests that the (m,n)=(1,1) mode plays an important role in both types of disruptions. Further, for the first time, it is unambiguously shown, using a fast electron cyclotron emission (ECE) instrument for the electron temperature profile measurements, that the (m,n)=(1,1) precursor to the high density disruptions has a 'cold bubble' structure. The precursor to the major disruption at high density resembles the 'vacuum bubble' model of disruptions first proposed by Kadomtsev and Pogutse. (author) 2 refs., 2 figs

  5. Analysis of the mechanical response of biomimetic materials with highly oriented microstructures through 3D printing, mechanical testing and modeling.

    de Obaldia, Enrique Escobar; Jeong, Chanhue; Grunenfelder, Lessa Kay; Kisailus, David; Zavattieri, Pablo

    2015-08-01

    Many biomineralized organisms have evolved highly oriented nanostructures to perform specific functions. One key example is the abrasion-resistant rod-like microstructure found in the radular teeth of Chitons (Cryptochiton stelleri), a large mollusk. The teeth consist of a soft core and a hard shell that is abrasion resistant under extreme mechanical loads with which they are subjected during the scraping process. Such remarkable mechanical properties are achieved through a hierarchical arrangement of nanostructured magnetite rods surrounded with α-chitin. We present a combined biomimetic approach in which designs were analyzed with additive manufacturing, experiments, analytical and computational models to gain insights into the abrasion resistance and toughness of rod-like microstructures. Staggered configurations of hard hexagonal rods surrounded by thin weak interfacial material were printed, and mechanically characterized with a cube-corner indenter. Experimental results demonstrate a higher contact resistance and stiffness for the staggered alignments compared to randomly distributed fibrous materials. Moreover, we reveal an optimal rod aspect ratio that lead to an increase in the site-specific properties measured by indentation. Anisotropy has a significant effect (up to 50%) on the Young's modulus in directions parallel and perpendicular to the longitudinal axis of the rods, and 30% on hardness and fracture toughness. Optical microscopy suggests that energy is dissipated in the form of median cracks when the load is parallel to the rods and lateral cracks when the load is perpendicular to the rods. Computational models suggest that inelastic deformation of the rods at early stages of indentation can vary the resistance to penetration. As such, we found that the mechanical behavior of the system is influenced by interfacial shear strain which influences the lateral load transfer and therefore the spread of damage. This new methodology can help to elucidate

  6. Two scale damage model and related numerical issues for thermo-mechanical high cycle fatigue

    Desmorat, R.; Kane, A.; Seyedi, M.; Sermage, J.P.

    2007-01-01

    On the idea that fatigue damage is localized at the microscopic scale, a scale smaller than the mesoscopic one of the Representative Volume Element (RVE), a three-dimensional two scale damage model has been proposed for High Cycle Fatigue applications. It is extended here to aniso-thermal cases and then to thermo-mechanical fatigue. The modeling consists in the micro-mechanics analysis of a weak micro-inclusion subjected to plasticity and damage embedded in an elastic meso-element (the RVE of continuum mechanics). The consideration of plasticity coupled with damage equations at micro-scale, altogether with Eshelby-Kroner localization law, allows to compute the value of microscopic damage up to failure for any kind of loading, 1D or 3D, cyclic or random, isothermal or aniso-thermal, mechanical, thermal or thermo-mechanical. A robust numerical scheme is proposed in order to make the computations fast. A post-processor for damage and fatigue (DAMAGE-2005) has been developed. It applies to complex thermo-mechanical loadings. Examples of the representation by the two scale damage model of physical phenomena related to High Cycle Fatigue are given such as the mean stress effect, the non-linear accumulation of damage. Examples of thermal and thermo-mechanical fatigue as well as complex applications on real size testing structure subjected to thermo-mechanical fatigue are detailed. (authors)

  7. Mechanics of high-capacity electrodes in lithium-ion batteries

    Zhu, Ting

    2016-01-01

    Rechargeable batteries, such as lithium-ion batteries, play an important role in the emerging sustainable energy landscape. Mechanical degradation and resulting capacity fade in high-capacity electrode materials critically hinder their use in high-performance lithium-ion batteries. This paper presents an overview of recent advances in understanding the electrochemically-induced mechanical behavior of the electrode materials in lithium-ion batteries. Particular emphasis is placed on stress generation and facture in high-capacity anode materials such as silicon. Finally, we identify several important unresolved issues for future research. (topical review)

  8. Noise measurements during high-frequency oscillatory and conventional mechanical ventilation.

    Berens, R J; Weigle, C G

    1995-10-01

    To evaluate the noise levels with high-frequency oscillatory ventilation and conventional mechanical ventilation. An observational, prospective study. Pediatric intensive care unit. The caretakers and environment of the pediatric intensive care unit. High-frequency oscillatory and conventional mechanical ventilation. Caretakers evaluated noise using a visual analog scale. Noise was measured with a decibel meter and an octave band frequency filter. There was twice as much noise perceived by the caretakers and as measured on the decibel A scale. All measures showed significantly greater noise, especially at low frequencies, with high-frequency oscillatory ventilation. High-frequency oscillatory ventilation exposes the patient to twice as much noise as does the use of conventional mechanical ventilation.

  9. Food irradiation: advantages and limitations

    Hernandes, N.K.; Vital, H. de C.; Sabaa-Srur, A.U.O.

    2003-01-01

    Food irradiation is a physical method of processing food (e.g. freezing, canning). It has been thoroughly researched over the last four decades and is recognized as a safe and wholesome method. It has the potential both of disinfesting dried food to reduce storage losses and disinfesting fruits and vegetables to meet quarantine requirements for export trade. Low doses of irradiation inhibit spoilage losses due to sprouting of root and tuber crops. Food- borne diseases due to contamination by pathogenic microorganisms and parasites of meat, poultry, fish, fishery products and spices are on the increase. Irradiation of these solid foods can decontaminate them of pathogenic organisms and thus provide safe food to the consumer. Irradiation can successfully replace the fumigation treatment of cocoa beans and coffee beans and disinfest dried fish, dates, dried fruits, etc. One of the most important advantages of food irradiation processing is that it is a coldprocess which does not significantly alter physico-chemical characters of the treated product. It can be applied to food after its final packaging. Similar to other physical processes of food processing, (e.g. canning, freezing), irradiation is a capital intensive process. Thus, adequate product volume must be made available in order to maximize the use of the facility and minimize the unit cost of treatment. Lack of harmonization of regulations among the countries which have approved irradiated foods hampers the introduction of this technique for international trade. Action at the international level has to be taken in order to remedy this situation. One of the important limitations of food irradiation processing is its slow acceptance by consumers, due inter alia to a perceived association with radioactivity. The food industry tends to be reluctant to use the technology in view of uncertainties regarding consumer acceptance of treated foods. Several market testing and consumer acceptance studies have been carried

  10. High-temperature mechanical properties of high-purity 70 mass% Cr-Fe alloy

    Asahina, M.; Harima, N.; Takaki, S.; Abiko, K. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    2002-01-16

    An ingot of high-purity 70 mass% Cr-Fe alloy was prepared by high-frequency induction melting in a high-purity argon atmosphere using a cold copper crucible. Its tensile properties such as hot-ductility and tensile strength were measured, and compared with the results for a high-purity 50 mass% Cr-Fe alloy, a high-purity 60 mass% Cr-Fe alloy and a Ni-based super-alloy. The formation of {sigma}-phase was also examined. The purity of a 70Cr-Fe alloy (70 mass% Cr-Fe alloy) ingot is more than 99.98 mass% and the total amount of gaseous impurities (C, N, O, S, H) in the 70Cr-Fe alloy is 69.9 mass ppm. The strength of the 70Cr-Fe alloy is higher than those of the 60Cr-Fe alloy and the 50Cr-Fe alloy at the temperatures between 293 and 1573 K, without decrease in ductility with increasing Cr content. The 70Cr-Fe alloy also possesses excellent high-temperature ductility. The {sigma}-phase was not observed after aging of 3.6 Ms at 873 K. Consequently, the 70Cr-Fe alloy is an excellent alloy as the base of super heat-resistant alloys. (orig.)

  11. Strengthening mechanisms in nanostructured high-purity aluminium deformed to high strain and annealed

    Kamikawa, Naoya; Huang, Xiaoxu; Tsuji, Nobuhiro

    2009-01-01

    Samples of pure aluminium (99.99%) have been produced by accumulative roll-bonding to a large strain followed by a heat treatment, where a two-step annealing process has been used to produce samples with large variations in structural parameters such as boundary spacing, misorientation angle...... and dislocation density. These parameters have been quantified by a structural analysis applying transmission electron microscopy and electron backscatter diffraction, and the mechanical properties have been determined by tensile testing at room temperature. Strength–structure relationships have been analysed...... based on the operation of two strengthening mechanisms—grain boundary and dislocation strengthening—and good agreement with experiments has been found for the deformed sample. However, for samples where the density of dislocation sources has been reduced significantly by annealing, an additional...

  12. Damping mechanisms of high-lying single-particle states in 91Nb

    Molen, H. K. T. van der; Berg, A. M. van den; Harakeh, M. N.; Hunyadi, M.; Kalantar-Nayestanaki, N.; Akimune, H.; Daito, I.; Fujimura, H.; Ihara, F.; Inomata, T.; Ishibashi, K.; Yoshida, H.; Yosoi, M.; Fujita, Y.; Fujiwara, M.; Jaenecke, J.; O'Donnell, T. W.; Laurent, H.; Lhenry, I.; Rodin, V. A.

    2007-01-01

    Decay by proton emission from high-lying states in 91 Nb, populated in the 90 Zr(α,t) reaction at E α =180 MeV, has been investigated. Decay to the ground state and semidirect decay to the low-lying (2 + ,5 - , and 3 - ) phonon states in 90 Zr were observed. It was found that these phonon states play an important role in the damping process of the single-particle states. An optical-model coupled-channel approach was used successfully to describe the direct and semidirect parts of the decay

  13. PBMR Project - Pebble Fuel Advantages

    Slabber, Johan; Matzie, Regis; Casperson, Sten; Kriel, Willem

    2006-01-01

    An overview is presented of all the important issues that influenced the choice of pebble fuel for the High-temperature Gas-cooled Reactor (HTGR) concept developed by South Africa. Each of these issues is then discussed in detail and compared with other fuel configurations proposed for direct cycle High-temperature Reactor (HTR) applications. The comparisons are provided using objective data generated by analyses done for the design of the Pebble Bed Modular Reactor (PBMR) and data that is available in open literature for the other fuel configurations

  14. High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned

    Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig

    2014-01-01

    The integration and deployment testing of the High Gain Antenna System for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based, deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity negation mechanism, and use of dynamic modeling is described and lessons learned presented.

  15. Comparison between the mechanical and radiative electron-capture processes at high energies

    Gonzalez, A.D.; Miraglia, J.E.

    1984-01-01

    The ground-state--ground-state mechanical and radiative electron-capture processes are studied at very high, but not relativistic, projectile velocities. Three-body calculations were carried out with use of the continuum distorted-wave theoretical method for both processes. Total cross sections and final-atom angular distributions were computed, and the importance of each mechanism examined. For total cross sections, the numerical results reaffirm that the radiative process is the predominant mechanism at very high projectile energies. For a given incident charge, the range of projectile energies in which the nonrelativistic radiative mechanism is the most important decreases as the target charge increases. It is found that the radiative mechanism produces a very sharp final-atom angular distribution in the forward direction. When both processes, the radiative and mechanical, give the same total cross section, the calculations show that the radiative differential cross section in the forward direction is almost 2 orders of magnitude larger than the mechanical one

  16. A numerical study on the mechanical properties and the processing behaviour of composite high strength steels

    Muenstermann, Sebastian [RWTH Aachen (Germany). Dept. of Ferrous Metallurgy; Vajragupta, Napat [RWTH Aachen (Germany). Materials Mechanics Group; Weisgerber, Bernadette [ThyssenKrupp Steel Europe AG (Germany). Patent Dept.; Kern, Andreas [ThyssenKrupp Steel Europe AG (Germany). Dept. of Quality Affairs

    2013-06-01

    The demand for lightweight construction in mechanical and civil engineering has strongly promoted the development of high strength steels with excellent damage tolerance. Nowadays, the requirements from mechanical and civil engineering are even more challenging, as gradients in mechanical properties are demanded increasingly often for components that are utilized close to the limit state of load bearing capacity. A metallurgical solution to this demand is given by composite rolling processes. In this process components with different chemical compositions were jointed, which develop after heat treatment special properties. These are actually evaluated in order to verify that structural steels with the desired gradients in mechanical properties can be processed. A numerical study was performed aiming to numerically predict strenght and toughness properties, as well as the procesing behaviour using Finite Element (FE) simulations with damage mechanics approaches. For determination of mechanical properties, simulations of tensile specimen, SENB sample, and a mobile crane have been carried out for different configurations of composite rolled materias out of high strebght structural steels. As a parameter study, both the geometrical and the metallurgical configurations of the composite rolled steels were modified. Thickness of each steel layer and materials configuration have been varied. Like this, a numerical procedure to define optimum tailored configurations of high strenght steels could be established.

  17. The advantages of SMRT sequencing

    Roberts, Richard J; Carneiro, Mauricio O; Schatz, Michael C

    2013-01-01

    Of the current next-generation sequencing technologies, SMRT sequencing is sometimes overlooked. However, attributes such as long reads, modified base detection and high accuracy make SMRT a useful technology and an ideal approach to the complete sequencing of small genomes.

  18. Microstructures and mechanical properties of Ti5553 alloy processed by high-pressure torsion

    Jiang, B. Z.; Emura, S.; Tsuchiya, K.

    2014-08-01

    In the present research, the effects of high-pressure torsion (HPT) processing on the microstructure and mechanical properties of Ti-5Al-5Mo-5V-3Cr (Ti5553) alloy were studied. HPT processing produced a white etching layer (WEL) in the middle section of the cross-section and numerous shear bands in the surface region of the cross-section. And the thickness of the WEL increased with increasing the HPT revolutions. TEM observation of the WEL revealed an ultrafine-grained structure with high degree of lattice distortions. The mechanical properties measurements showed that the hardness and ultimate tensile strength increased by HPT processing, accompanied with a decrease in the elongation to failure. It is considered that the mechanical properties of HPT processed Ti5553 alloy are mostly dominated by the shear banded region and the WEL where have the finest grain size and high density of dislocations.

  19. Microstructures and mechanical properties of Ti5553 alloy processed by high-pressure torsion

    Jiang, B Z; Emura, S; Tsuchiya, K

    2014-01-01

    In the present research, the effects of high-pressure torsion (HPT) processing on the microstructure and mechanical properties of Ti-5Al-5Mo-5V-3Cr (Ti5553) alloy were studied. HPT processing produced a white etching layer (WEL) in the middle section of the cross-section and numerous shear bands in the surface region of the cross-section. And the thickness of the WEL increased with increasing the HPT revolutions. TEM observation of the WEL revealed an ultrafine-grained structure with high degree of lattice distortions. The mechanical properties measurements showed that the hardness and ultimate tensile strength increased by HPT processing, accompanied with a decrease in the elongation to failure. It is considered that the mechanical properties of HPT processed Ti5553 alloy are mostly dominated by the shear banded region and the WEL where have the finest grain size and high density of dislocations

  20. A high-compression electron gun for C6+ production: concept, simulations and mechanical design

    Mertzig, Robert; Breitenfeldt, M.; Mathot, S.; Pitters, J.; Shornikov, A.; Wenander, F.

    2017-07-01

    In this paper we report on simulations and the mechanical design of a high-compression electron gun for an Electron Beam Ion Source (EBIS) dedicated for production of high intensity and high repetition rate pulses of bare carbon ions for injection into linac-based hadron therapy facilities. The gun is presently under construction at CERN to be retrofitted into the TwinEBIS test bench for experimental studies. We describe the design constraints, show results of numeric simulations and report on the mechanical design featuring several novel ideas. The reported design makes use of combined-function units with reduced number of mechanical joints that were carefully controlled and tuned during the manufacturing phase. The simulations addressed a wide range of topics including the influence of thermal effects, focusing optics, symmetry-breaking misalignments and injection into a full 5 T field.

  1. Proposal of a high rigidity and high speed rotating mechanism using a new concept hydrodynamic bearing in X-ray tube for high speed computed tomography

    Hattori, Hitoshi; Fukushima, Harunobu; Yoshii, Yasuo; Nakamuta, Hironori; Iwase, Mitsuo; Kitade, Koichi

    2009-01-01

    In this paper, a high rigidity and high speed rotating mechanism using a new concept hydrodynamic bearing in X-ray tube for high speed computed tomography is proposed. In order to obtain both the stability and the high load carrying capacity, the hydrodynamic bearing lubricated by liquid metal (Gallium alloy), named as the hybrid hydrodynamic bearing generates the lubricating film by wedge effect on the plane region between the spiral grooves under high loading condition. The parallelism between the bearing and the rotating body can be secured by optimizing the rigidity distribution of stationary shaft in the proposed rotating mechanism. By carrying out the fundamental design by numerical analyses, it has been made clear that the hybrid hydrodynamic bearing and the rotating mechanism are suitable for the X-ray tube used in the CT with ever-increasingly scanning speed. (author)

  2. IMPLEMENTING SINGLE RESOLUTION MECHANISMADVANTAGES AND CHALLENGES

    Iuliana MILITARU; Antoniu PREDESCU; Daniela BOJAN

    2015-01-01

    Banking system of European Union was unsettled by present economic and financial crisis, and also both principle and effectiveness of Banking Union of EU. In effect, Banking Union confronts with risk aversion, bank run and financial disintegration, which explains why it was decided, for EU’s Banking Union, to build European Banking Union (EBU), as key element of European Monetary Union (EMU). EBU must be a comunitary tool for monitoring and harmonising banking system of EU, with three main co...

  3. Trampoline Resonator Fabrication for Tests of Quantum Mechanics at High Mass

    Weaver, Matthew; Pepper, Brian; Sonin, Petro; Eerkens, Hedwig; Buters, Frank; de Man, Sven; Bouwmeester, Dirk

    2014-03-01

    There has been much interest recently in optomechanical devices that can reach the ground state. Two requirements for achieving ground state cooling are high optical finesse in the cavity and high mechanical quality factor. We present a set of trampoline resonator devices using high stress silicon nitride and superpolishing of mirrors with sufficient finesse (as high as 60,000) and quality factor (as high as 480,000) for ground state cooling in a dilution refrigerator. These devices have a higher mass, between 80 and 100 ng, and lower frequency, between 200 and 500 kHz, than other devices that have been cooled to the ground state, enabling tests of quantum mechanics at a larger mass scale.

  4. A new soft dielectric silicone elastomer matrix with high mechanical integrity and low losses

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede

    2015-01-01

    Though dielectric elastomers (DEs) have many favourable properties, the issue of high driving voltages limits the commercial viability of the technology. Driving voltage can be lowered by decreasing the Young's modulus and increasing the dielectric permittivity of silicone elastomers. A decrease...... in Young's modulus, however, is often accompanied by the loss of mechanical stability and thereby the lifetime of the DE. A new soft elastomer matrix, with no loss of mechanical stability and high dielectric permittivity, was prepared through the use of alkyl chloride-functional siloxane copolymers...

  5. Investigation of mechanical and structural characteristics of platinum and palladium at high temperatures

    Trumie, B. T.; Gomidzelovie, L.; Marjanovic, S. R.; Krstic, V. R.

    2015-03-30

    In order to broaden future application of products based on platinum and palladium a comparative analysis of their high-temperature mechanical properties was performed. Platinum and palladium are of great importance and are widely used in chemical industry, electronics, for making laboratory dishes, to name a few. Mechanical properties of pure metals, such as: tensile strength, creep rate and rupture time were investigated using universal testing machine for tensile testing of materials. Microstructure of samples was investigated by optical microscopy. Based on obtained results it can be concluded that the platinum, compared to palladium, is superior for high-temperature applications. (Author)

  6. Investigation of mechanical and structural characteristics of platinum and palladium at high temperatures

    Trumie, B. T.; Gomidzelovie, L.; Marjanovic, S. R.; Krstic, V. R.

    2015-01-01

    In order to broaden future application of products based on platinum and palladium a comparative analysis of their high-temperature mechanical properties was performed. Platinum and palladium are of great importance and are widely used in chemical industry, electronics, for making laboratory dishes, to name a few. Mechanical properties of pure metals, such as: tensile strength, creep rate and rupture time were investigated using universal testing machine for tensile testing of materials. Microstructure of samples was investigated by optical microscopy. Based on obtained results it can be concluded that the platinum, compared to palladium, is superior for high-temperature applications. (Author)

  7. Structuring the competitive advantage of printing company

    Kukharuk A. D.

    2013-01-01

    The nature of the concept of "competitive advantage of the company" if analyzed. The concept of "structuring a competitive advantage" is suggested. The model of structuring of printing company’s competitive advantage based on fundamentals of stakeholder theory is developed.

  8. 76 FR 56262 - Community Advantage Pilot Program

    2011-09-12

    ... SMALL BUSINESS ADMINISTRATION [Docket No. SBA 2011-0003] Community Advantage Pilot Program AGENCY: U.S. Small Business Administration (SBA). ACTION: Notice of change to Community Advantage Pilot... Community Advantage Pilot Program. In that notice, SBA modified or waived as appropriate certain regulations...

  9. Advantages of robotics in benign gynecologic surgery.

    Truong, Mireille; Kim, Jin Hee; Scheib, Stacey; Patzkowsky, Kristin

    2016-08-01

    The purpose of this article is to review the literature and discuss the advantages of robotics in benign gynecologic surgery. Minimally invasive surgery has become the preferred route over abdominal surgery. The laparoscopic or robotic approach is recommended when vaginal surgery is not feasible. Thus far, robotic gynecologic surgery data have demonstrated feasibility, safety, and equivalent clinical outcomes in comparison with laparoscopy and better clinical outcomes compared with laparotomy. Robotics was developed to overcome challenges of laparoscopy and has led to technological advantages such as improved ergonomics, visualization with three-dimensional capabilities, dexterity and range of motion with instrument articulation, and tremor filtration. To date, applications of robotics in benign gynecology include hysterectomy, myomectomy, endometriosis surgery, sacrocolpopexy, adnexal surgery, tubal reanastomosis, and cerclage. Though further data are needed, robotics may provide additional benefits over other approaches in the obese patient population and in higher complexity cases. Challenges that arose in the earlier adoption stage such as the steep learning curve, costs, and operative times are becoming more optimized with greater experience, with implementation of robotics in high-volume centers and with improved training of surgeons and robotic teams. Robotic laparoendoscopic single-site surgery, albeit still in its infancy where technical advantages compared with laparoscopic single-site surgery are still unclear, may provide a cost-reducing option compared with multiport robotics. The cost may even approach that of laparoscopy while still conferring similar perioperative outcomes. Advances in robotic technology such as the single-site platform and telesurgery, have the potential to revolutionize the field of minimally invasive gynecologic surgery. Higher quality evidence is needed to determine the advantages and disadvantages of robotic surgery in benign

  10. Design of a high-resolution high-stability positioning mechanism for crystal optics

    Shu, D.; Toellner, T. S.; Alp, E. E.

    1999-01-01

    The authors present a novel miniature multi-axis driving structure that will allow positioning of two crystals with better than 50-nrad angular resolution and nanometer linear driving sensitivity.The precision and stability of this structure allow the user to align or adjust an assembly of crystals to achieve the same performance as does a single channel-cut crystal, so they call it an artificial channel-cut crystal. In this paper, the particular designs and specifications, as well as the test results,for a two-axis driving structure for a high-energy-resolution artificial channel-cut crystal monochromator are presented

  11. Highly Porous, Rigid-Rod Polyamide Aerogels with Superior Mechanical Properties and Unusually High Thermal Conductivity.

    Williams, Jarrod C; Nguyen, Baochau N; McCorkle, Linda; Scheiman, Daniel; Griffin, Justin S; Steiner, Stephen A; Meador, Mary Ann B

    2017-01-18

    We report here the fabrication of polyamide aerogels composed of poly-p-phenylene-terephthalamide, the same backbone chemistry as DuPont's Kevlar. The all-para-substituted polymers gel without the use of cross-linker and maintain their shape during processing-an improvement over the meta-substituted cross-linked polyamide aerogels reported previously. Solutions containing calcium chloride (CaCl 2 ) and para-phenylenediamine (pPDA) in N-methylpyrrolidinone (NMP) at low temperature are reacted with terephthaloyl chloride (TPC). Polymerization proceeds over the course of 5 min resulting in gelation. Removal of the reaction solvent via solvent exchange followed by extraction with supercritical carbon dioxide provides aerogels with densities ranging from 0.1 to 0.3 g/cm 3 , depending on the concentration of calcium chloride, the formulated number of repeat units, n, and the concentration of polymer in the reaction mixture. These variables were assessed in a statistical experimental study to understand their effects on the properties of the aerogels. Aerogels made using at least 30 wt % CaCl 2 had the best strength when compared to aerogels of similar density. Furthermore, aerogels made using 30 wt % CaCl 2 exhibited the lowest shrinkage when aged at elevated temperatures. Notably, whereas most aerogel materials are highly insulating (thermal conductivities of 10-30 mW/m K), the polyamide aerogels produced here exhibit remarkably high thermal conductivities (50-80 mW/(m K)) at the same densities as other inorganic and polymer aerogels. These high thermal conductivities are attributed to efficient phonon transport by the rigid-rod polymer backbone. In conjunction with their low cost, ease of fabrication with respect to other polymer aerogels, low densities, and high mass-normalized strength and stiffness properties, these aerogels are uniquely valuable for applications such as lightweighting in consumer electronics, automobiles, and aerospace where weight reduction is

  12. High-temperature mechanical relaxation in glass-like B2O3

    Lomovskoj, V.A.

    1987-01-01

    The study of high-temperature mechanical relaxation in glass-like B 2 O 3 was carried out at the temperatures from 470 to 620 K using the method of internal friction at freely damped tortional vibrations (frequency range is 0.05 - 10 Hz) and forced torsional vibrations (frequency range is 0.1 -0.00001 Hz). Possible mechanisms of high-temperature mechanical relaxation are considered. It is shown that several possible mechanisms of high-temperature mechanical relaxation in glass-like B 2 O 3 can be singled out. Switching of B-O bridge bond between two boroxol cycles of boroxol grouping for oxygen vacancy in spatial structure of glass-like B 2 O 3 , formed as a result of thermal breaking of one out of three B-O bonds, according to diffusion theory of glass viscosity. The slip of one layer boroxol groupings as to another one in the presence of only tricoordinated boron atoms in the structure of glass-like B 2 O 3

  13. Effect of processing conditions on the mechanical and thermal properties of high-impact polypropylene nanocomposites

    Furlan, L G [Federal Institute of Rio Grande do Sul, IFRS, Campus Restinga, Estrada Joao Antonio da Silveira, 351, Porto Alegre 91790-400 (Brazil); Ferreira, C I; Dal Castel, C; Santos, K S; Mello, A C.E. [Chemistry Institute, Federal University of Rio Grande do Sul, UFRGS, Av. Bento Goncalves, 9500, Porto Alegre 91501-970 (Brazil); Liberman, S A; Oviedo, M A.S. [Braskem S.A., III Polo Petroquimico, Via Oeste, Lote 5, Triunfo 95853-000 (Brazil); Mauler, R.S., E-mail: mauler@iq.ufrgs.br [Chemistry Institute, Federal University of Rio Grande do Sul, UFRGS, Av. Bento Goncalves, 9500, Porto Alegre 91501-970 (Brazil)

    2011-08-25

    Highlights: {yields} Polypropylene montmorillonite (PP-MMT) produced at different processing conditions. {yields} Polypropylene Nanocomposites with higher increase on impact resistance. {yields} Higher enhancement on mechanical properties. - Abstract: Polypropylene montmorillonite (PP-MMT) nanocomposites have been prepared by using a co-rotating twin screw extruder. The effects of processing conditions at fixed clay content (5 wt%) on polymer properties were investigated by means of transmission electron microscopy (TEM), flexural modulus, izod impact, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). It was noticed that the morphology and the mechanical properties of polypropylene nanocomposites were affected by different screw shear configuration. The results showed that the higher enhancement on mechanical properties was obtained by medium shear intensity profile instead of high configuration. An exceptional increase (maximum of 282%) on impact resistance was observed.

  14. Effect of processing conditions on the mechanical and thermal properties of high-impact polypropylene nanocomposites

    Furlan, L.G.; Ferreira, C.I.; Dal Castel, C.; Santos, K.S.; Mello, A.C.E.; Liberman, S.A.; Oviedo, M.A.S.; Mauler, R.S.

    2011-01-01

    Highlights: → Polypropylene montmorillonite (PP-MMT) produced at different processing conditions. → Polypropylene Nanocomposites with higher increase on impact resistance. → Higher enhancement on mechanical properties. - Abstract: Polypropylene montmorillonite (PP-MMT) nanocomposites have been prepared by using a co-rotating twin screw extruder. The effects of processing conditions at fixed clay content (5 wt%) on polymer properties were investigated by means of transmission electron microscopy (TEM), flexural modulus, izod impact, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). It was noticed that the morphology and the mechanical properties of polypropylene nanocomposites were affected by different screw shear configuration. The results showed that the higher enhancement on mechanical properties was obtained by medium shear intensity profile instead of high configuration. An exceptional increase (maximum of 282%) on impact resistance was observed.

  15. Structural evolution and formation mechanisms of TiC/Ti nanocomposites prepared by high-energy mechanical alloying

    Gu Dongdong; Meiners, Wilhelm; Hagedorn, Yves-christian; Wissenbach, Konrad; Poprawe, Reinhart

    2010-01-01

    In this work, high-energy ball milling of a micrometre-scaled Ti and TiC powder mixture was performed to prepare TiC/Ti nanocomposites. The constituent phases and microstructural characteristics of the milled powders were studied by an x-ray diffractometer, a scanning electron microscope, an energy dispersive x-ray spectroscope and a transmission electron microscope. Formation mechanisms and theoretical basis of the microstructural development were elucidated. It showed that on increasing the applied milling time, the structures of the Ti constituent experienced a successive change from hcp (5 h) to fcc (10 h) and finally to an amorphous state (≥15 h). The hydrostatic stresses caused by the excess free volume at grain boundaries were calculated to be 3.96 and 5.59 GPa for the Ti constituent in 5 and 10 h milled powders, which was responsible for the hcp to fcc polymorphic change. The amorphization of Ti constituent was due to the large defect concentration induced by severe plastic deformation during milling. The milled powder particles underwent two stages of significant refinement at 10 and 20 h during milling. For a higher milling time above 25 h, powder characteristics and chemical compositions became stable. The competitive action and the final equilibrium between the mechanisms of fracturing and cold welding accounted for the microstructural evolution. The ball milled products were typically nanocomposite powders featured by a nanocrystalline/amorphous Ti matrix reinforced with uniformly dispersed TiC nanoparticles. The finest crystalline sizes of the Ti and TiC constituents were 17.2 nm (after 10 h milling) and 13.5 nm (after 20 h milling), respectively.

  16. Effects of high NH4+ on K+ uptake, culm mechanical strength and grain filling in wheat

    Lingan eKong

    2014-12-01

    Full Text Available It is well established that a high external NH4+ concentration depresses many processes in plant development, but the underlying mechanisms are still not well understood. To determine whether the negative effects of high levels of NH4+ are related to competitive cation uptake, wheat was grown in a field with moderate (18 g N m-2 and high (30 g N m-2 supplies of NH4+ in the presence or absence of additional K+ (6 g K2O m-2 to examine culm mechanical strength, the main components of the vascular bundle, nitrogen (N remobilization and the grain-filling rate. The results indicated that an excessive supply of NH4+ significantly decreased culm mechanical strength, the cellulose and lignin contents of vascular bundles, the N remobilization efficiency (NRE and the grain-filling rate compared with a moderate level of NH4+. The additional provision of K+ considerably alleviated these negative effects of high NH4+, resulting in a 19.41%-26.95% increase in culm mechanical strength during grain filling and a 34.59% increase in the NRE. An assay using the scanning ion-selective electrode technique (SIET showed that the net rate of transmembrane K+ influx decreased by 84.62%, and measurements using flame photometry demonstrated that the K+ content decreased by 36.13% in wheat plants subjected to high NH4+. This study indicates that the effects of high NH4+ on culm mechanical strength, cellulose and lignin contents, the NRE and the grain-filling rate are probably associated with inhibition of K+ uptake in wheat.

  17. Characterization of mechanical properties and microstructure of highly irradiated SS 316

    Karthik, V., E-mail: karthik@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kumar, RanVijay; Vijayaragavan, A.; Venkiteswaran, C.N.; Anandaraj, V.; Parameswaran, P.; Saroja, S.; Muralidharan, N.G.; Joseph, Jojo; Kasiviswanathan, K.V.; Jayakumar, T.; Raj, Baldev [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2013-08-15

    Cold worked austenitic stainless steel type AISI 316 is used as the material for fuel cladding and wrapper of the Fast Breeder Test Reactor (FBTR), India. The evaluation of mechanical properties of these core structurals is very essential to assess its integrity and ensure safe and productive operation of FBTR to very high burn-ups. The changes in the mechanical properties of these core structurals are associated with microstructural changes caused by high fluence neutron irradiation and temperatures of 673–823 K. Remote tensile testing has been used for evaluating the tensile properties of irradiated clad tubes and shear punch test using small disk specimens for evaluating the properties of irradiated hexagonal wrapper. This paper will highlight the methods employed for evaluating the mechanical properties of the irradiated cladding and wrapper and discuss the trends in properties as a function of dpa (displacement per atom) and irradiation temperature.

  18. Modeling of mechanical behavior of quenched zirconium-based nuclear fuel claddings after a high temperature oxidation

    Cabrera-Salcedo, A.

    2012-01-01

    During the second stage of Loss Of Coolant Accident (LOCA) in Pressurized Water Reactors (PWR) zirconium-based fuel claddings undergo a high temperature oxidation (up to 1200 C), then a water quench. After a single-side steam oxidation followed by a direct quench, the cladding is composed of three layers: an oxide (Zirconia) outer layer (formed at HT), always brittle at Room Temperature (RT), an intermediate oxygen stabilized alpha layer, always brittle at RT, called alpha(O), and an inner 'prior-beta' layer, which is the only layer able to keep some significant Post Quench (PQ) ductility at RT. However, hydrogen absorbed because of service exposure or during the LOCA transient, concentrates in this layer and may leads to its embrittlement. To estimate the PQ mechanical properties of these materials, Ring Compression Tests (RCT) are widely used because of their simplicity. Small sample size makes RCTs advantageous when a comparison with irradiated samples is required. Despite their good reproducibility, these tests are difficult to interpret as they often present two or more load drops on the engineering load-displacement curve. Laboratories disagree about their interpretation. This study proposes an original fracture scenario for a stratified PQ cladding tested by RCT, and its associated FE model. Strong oxygen content gradient effect on layers mechanical properties is taken into account in the model. PQ thermal stresses resulting from water quench of HT oxidized cladding are investigated, as well as progressive damage of three layers during an RCT. The proposed scenario is based on interrupted RCT analysis, post- RCT sample's outer layers observation for damage evaluation, RCTs of prior-beta single-layer rings, and mechanical behavior of especially chemically adjusted samples. The force displacement curves appearance is correctly reproduced using the obtained FE model. The proposed fracture scenario elucidates RCTs of quenched zirconium-based nuclear fuel

  19. A miniaturized, high frequency mechanical scanner for high speed atomic force microscope using suspension on dynamically determined points

    Herfst, Rodolf; Dekker, Bert; Witvoet, Gert; Crowcombe, Will; Lange, Dorus de [Department of Optomechatronics, Netherlands Organization for Applied Scientific Research, TNO, Delft (Netherlands); Sadeghian, Hamed, E-mail: hamed.sadeghianmarnani@tno.nl, E-mail: h.sadeghianmarnani@tudelft.nl [Department of Optomechatronics, Netherlands Organization for Applied Scientific Research, TNO, Delft (Netherlands); Department of Precision and Microsystems Engineering, Delft University of Technology, Delft (Netherlands)

    2015-11-15

    One of the major limitations in the speed of the atomic force microscope (AFM) is the bandwidth of the mechanical scanning stage, especially in the vertical (z) direction. According to the design principles of “light and stiff” and “static determinacy,” the bandwidth of the mechanical scanner is limited by the first eigenfrequency of the AFM head in case of tip scanning and by the sample stage in terms of sample scanning. Due to stringent requirements of the system, simply pushing the first eigenfrequency to an ever higher value has reached its limitation. We have developed a miniaturized, high speed AFM scanner in which the dynamics of the z-scanning stage are made insensitive to its surrounding dynamics via suspension of it on specific dynamically determined points. This resulted in a mechanical bandwidth as high as that of the z-actuator (50 kHz) while remaining insensitive to the dynamics of its base and surroundings. The scanner allows a practical z scan range of 2.1 μm. We have demonstrated the applicability of the scanner to the high speed scanning of nanostructures.

  20. On the mechanism of high product selectivity for HCOOH using Pb in CO2 electroreduction.

    Back, Seoin; Kim, Jun-Hyuk; Kim, Yong-Tae; Jung, Yousung

    2016-04-14

    While achieving high product selectivity is one of the major challenges of the CO2 electroreduction technology in general, Pb is one of the few examples with high selectivity that produces formic acid almost exclusively (versus H2, CO, or other byproducts). In this work, we study the mechanism of CO2 electroreduction reactions using Pb to understand the origin of high formic acid selectivity. In particular, we first assess the proton-assisted mechanism proposed in the literature using density functional calculations and find that it cannot fully explain the previous selectivity experiments for the Pb electrode. We then suggest an alternative proton-coupled-electron-transfer mechanism consistent with existing observations, and further validate a new mechanism by experimentally measuring and comparing the onset potentials for CO2 reduction vs. H2 production. We find that the origin of a high selectivity of the Pb catalyst for HCOOH production over CO and H2 lies in the strong O-affinitive and weak C-, H-affinitive characteristics of Pb, leading to the involvement of the *OCHO species as a key intermediate to produce HCOOH exclusively and preventing unwanted H2 production at the same time.

  1. Influence of phase transformations on the mechanical behaviour of refractory ceramics at high temperature

    Schmitt, N.; Poirier, J.

    2009-01-01

    Refractories used at high temperature are subjected to high chemical and mechanical stresses. The mastery of their microstructure as well as the phase changes occurring in service is essential to ensure resistance to wear and failure of refractory linings. Great progress has been made: combining efficient techniques for the investigation of the microstructure with powerful numerical tools (thermochemical and thermo-mechanical computations) provides information (e.g., degradation mechanisms) that cannot be obtained directly. Also multi-physical and multi-scale models developing materials with high-performance for higher temperature and with longer lifetime. In this paper, through several examples we show some interactions between the mechanical behavior and the microstructure transformations of refractory ceramics. The tools developed to characterize their microstructure change in situ (e.g., at high temperature) and to identify their kinetics are described. Some methodologies and tools developed in recent years, today, provide a better understanding of in-service behavior of refractories while identifying the critical material and process parameters likely to increase life-time. (authors)

  2. Using High Speed Smartphone Cameras and Video Analysis Techniques to Teach Mechanical Wave Physics

    Bonato, Jacopo; Gratton, Luigi M.; Onorato, Pasquale; Oss, Stefano

    2017-01-01

    We propose the use of smartphone-based slow-motion video analysis techniques as a valuable tool for investigating physics concepts ruling mechanical wave propagation. The simple experimental activities presented here, suitable for both high school and undergraduate students, allows one to measure, in a simple yet rigorous way, the speed of pulses…

  3. Residual stress in a M3:2 PM high speed steel; effect of mechanical loading

    Højerslev, Christian; Odén, Magnus; Carstensen, Jesper V.

    2001-01-01

    X-ray lattice strains were investigated in an AISI M3:2 PM high-speed steel in the as heat treated condition and after exposure to alternating mechanical load. The volume changes during heat treatment were monitored with dilatometry. Hardened and tempered AISI M3:2 steel consists of tempered lath...

  4. Skylab experiments. Volume 6: Mechanics. [Skylab program accomplishments for high school level education

    1973-01-01

    Skylab program activities are presented in a form adapted to instruction of high school students. The overall goals of the program are discussed. The specific accomplishments of the mechanics investigations are described. The subjects involved are as follows: (1) evaluation of mobility aids, (2) mass measurement devices, and (3) space guidance crew/vehicle disturbances.

  5. Mechanism for the formation of sporadic-E layers in the high-latitude ionosphere

    Vlasov, M.N.; Mishin, E.V.; Telegin, V.A.

    1980-09-01

    A model of the collective interaction of precipitating electrons and the ionospheric plasma is used to explain the formation of short-duration sporadic-E layers in the high-latitude ionosphere. The changes produced in electron density by this collective interaction mechanism are considered.

  6. Statistical evaluation of the mechanical properties of high-volume class F fly ash concretes

    Yoon, Seyoon; Monteiro, Paulo J.M.; Macphee, Donald E.; Glasser, Fredrik P.; Imbabi, Mohammed Salah-Eldin

    2014-01-01

    the authors experimentally and statistically investigated the effects of mix-design factors on the mechanical properties of high-volume class F fly ash concretes. A total of 240 and 32 samples were produced and tested in the laboratory to measure compressive

  7. Simplifications and Idealizations in High School Physics in Mechanics: A Study of Slovenian Curriculum and Textbooks

    Forjan, Matej; Sliško, Josip

    2014-01-01

    This article presents the results of an analysis of three Slovenian textbooks for high school physics, from the point of view of simplifications and idealizations in the field of mechanics. In modeling of physical systems, making simplifications and idealizations is important, since one ignores minor effects and focuses on the most important…

  8. Filmless MRI. Advantages and disadvantages

    Vorbeck, F.; Al-Zayer, F.; Jung, B.; Breitenseher, M.; Imhof, H.

    1999-01-01

    At our hospital, an average MRI examination comprises 170 images. These examinations were evaluated exclusively on digital reporting systems with two high-resolution monitors for a period of 1 year. A retrospective analysis of this reporting method in comparision with films on a conventional viewing wall was performed with subjective and objective data. Radiologists and technicians were requested to evaluate the system on a subjective scale from 1 to 5 for seven topics (image analysis, inspection, time for reporting, handling, comparison with previous reports, quality of PC laser prints, training period). Moreover, personal interviews were conducted and protocols taken. Patient and image frequency, film costs, data transfer time and amount of system failures were evaluated as objective data. The most important results were: Two thirds of the film checking radiologists prefer the conventional viewing walls over the computer monitors. However, 70% of the residents prefer using the computer monitor for reporting. Seventy percent of the interviewed radiologists considered comparison with former examinations on film very difficult. Digitizing of former MRI examinations was not a convincing method; printing on a standard PC laser printer was considered to yield insufficient quality. The different acceptance between radiologists and residents seems to be related to different experiences. The reduction in film costs (48.6%) will improve further with complete PACS installation in the whole hospital. Data transfer rates are still poor; further improvement of network performance is necessary for convenient work. One whole MRI examination and report could be stored on CD-ROM for a cost of less than 2 euros. This could be a future means of cheap archiving and documentation suitable for viewing on any PC with DICOM III viewer. Images and reports could stay with the patient as in the past. (orig.) [de

  9. Hydrodynamic advantages of swimming by salp chains.

    Sutherland, Kelly R; Weihs, Daniel

    2017-08-01

    Salps are marine invertebrates comprising multiple jet-propelled swimming units during a colonial life-cycle stage. Using theory, we show that asynchronous swimming with multiple pulsed jets yields substantial hydrodynamic benefit due to the production of steady swimming velocities, which limit drag. Laboratory comparisons of swimming kinematics of aggregate salps ( Salpa fusiformis and Weelia cylindrica ) using high-speed video supported that asynchronous swimming by aggregates results in a smoother velocity profile and showed that this smoother velocity profile is the result of uncoordinated, asynchronous swimming by individual zooids. In situ flow visualizations of W. cylindrica swimming wakes revealed that another consequence of asynchronous swimming is that fluid interactions between jet wakes are minimized. Although the advantages of multi-jet propulsion have been mentioned elsewhere, this is the first time that the theory has been quantified and the role of asynchronous swimming verified using experimental data from the laboratory and the field. © 2017 The Author(s).

  10. The competitive advantage of sanctioning institutions.

    Gürerk, Ozgür; Irlenbusch, Bernd; Rockenbach, Bettina

    2006-04-07

    Understanding the fundamental patterns and determinants of human cooperation and the maintenance of social order in human societies is a challenge across disciplines. The existing empirical evidence for the higher levels of cooperation when altruistic punishment is present versus when it is absent systematically ignores the institutional competition inherent in human societies. Whether punishment would be deliberately adopted and would similarly enhance cooperation when directly competing with nonpunishment institutions is highly controversial in light of recent findings on the detrimental effects of punishment. We show experimentally that a sanctioning institution is the undisputed winner in a competition with a sanction-free institution. Despite initial aversion, the entire population migrates successively to the sanctioning institution and strongly cooperates, whereas the sanction-free society becomes fully depopulated. The findings demonstrate the competitive advantage of sanctioning institutions and exemplify the emergence and manifestation of social order driven by institutional selection.

  11. Effect of microstructure on high-temperature mechanical behavior of nickel-base superalloys for turbine disc applications

    Sharpe, Heather Joan

    2007-05-01

    Engineers constantly seek advancements in the performance of aircraft and power generation engines, including, lower costs and emissions, and improved fuel efficiency. Nickel-base superalloys are the material of choice for turbine discs, which experience some of the highest temperatures and stresses in the engine. Engine performance is proportional to operating temperatures. Consequently, the high-temperature capabilities of disc materials limit the performance of gas-turbine engines. Therefore, any improvements to engine performance necessitate improved alloy performance. In order to take advantage of improvements in high-temperature capabilities through tailoring of alloy microstructure, the overall objectives of this work were to establish relationships between alloy processing and microstructure, and between microstructure and mechanical properties. In addition, the projected aimed to demonstrate the applicability of neural network modeling to the field of Ni-base disc alloy development and behavior. The first phase of this work addressed the issue of how microstructure varies with heat treatment and by what mechanisms these structures are formed. Further it considered how superalloy composition could account for microstructural variations from the same heat treatment. To study this, four next-generation Ni-base disc alloys were subjected to various controlled heat-treatments and the resulting microstructures were then quantified. These quantitative results were correlated to chemistry and processing, including solution temperature, cooling rate, and intermediate hold temperature. A complex interaction of processing steps and chemistry was found to contribute to all features measured; grain size, precipitate distribution, grain boundary serrations. Solution temperature, above a certain threshold, and cooling rate controlled grain size, while cooling rate and intermediate hold temperature controlled precipitate formation and grain boundary serrations. Diffusion

  12. High precision mirror alignment mechanism for use in synchrotron radiation beamlines

    Verma, Adu; Srivastava, P.K.; Das, Suraj; Nookaraju, Mogali

    2009-01-01

    The performance of a synchrotron radiation beamline is highly depends on parameters, crucially on the manufacturing accuracies of the optical elements and very good alignment of optical elements in the beam path. To develop a synchrotron beamline the misalignment effects have to be estimated and the mechanical components that hold optical elements have to be designed and developed within the specified tolerance limits. The translational inaccuracies result in shifting the image spot, which affect the flux throughput. The misorientation errors i.e. the rotation of optical elements about their mean position affects the image quality. The horizontal misorientation i.e. the rotation of an optical element about an axis passing through its centre and perpendicular to the plane containing the mirror has the most sever effect on the spectral resolution of the beamline, because of an increase in the dispersive spot size at the image plane. The design development and testing of a high precision mirror alignment mechanism is reported in this abstract. Though this mirror alignment mechanism is developed for the X-ray diffraction beamline on synchrotron radiation source Indus-2, 2.5 GeV, 300 mA, the design is general purpose and can be adapted for any other synchrotron facility or a similar ultra high vacuum environment. The mirror alignment mechanism is based on a constrained kinematic chain which provides the angular motions about three co-ordinate axes in the range of 0 to ±1° with the backlash free resolution of 1 arc second. The linear motions in three orthogonal directions are performed by other kinematic mounts in the range of 0 to ± 10 mm with a fine adjustment of 10 μm. The motions are transferred from air to ultra high vacuum through bellows. The ultra high vacuum chamber has been designed, fabricated and tested as per the ASME code. The rotational motions of the mirror alignment mechanism has been tested using a laser interferometer. (author)

  13. Morphology and mechanical properties of PA12/plasticized starch blends prepared by high-shear extrusion

    Teyssandier, F.; Cassagnau, P.; Gérard, J.F.; Mignard, N.; Mélis, F.

    2012-01-01

    Highlights: ► High shear rate processing was found to greatly impact PA12/starch blend morphologies. ► The morphology was observed to be stable under subsequent processing conditions. ► The mechanical properties of the blends under high-shear rate were greatly improved. ► Polymer blend preparation via high-shear processing has proved to be very effective. ► Finally, polymer blends with improved mechanical properties were obtained. - Abstract: PA12/plasticized starch blends (PA12/TPS) were prepared by high-shear twin screw extruder. The morphology development and the mechanical properties of the blends were investigated as a function of the apparent shear rate. High-shear processing has proved to be an efficient method to finely disperse thermoplastic starch in polyamide 12 matrix. Blends containing TPS domains with a size at the nano-scale (R n ∼ 150 nm) homogeneously dispersed in PA12 matrix were obtained. From a modeling point of view, the variation of the droplet radius is closer to the Wu's predictions compared to the Serpe's predictions. From the basic hypothesis of these models, it can be then assumed that compatibilization between both phases occurs during the blend processing. Furthermore, this morphology of the blends has been proved to be stable after a reprocessing step in an internal mixer most likely due to either strong hydrogen bonds between the hydroxyl groups of starch and amide groups of polyamide 12 or to potentially cross reactions between macroradicals accounting for in situ formation of graft copolymers with the potential function of compatibilizers. Mechanical properties of the blends were found to be strongly dependent on the shear rate parameter of blend processing as the mechanical properties increase with shear rate. In agreement to the blend morphology, the elongation at break of the blends was greatly improved attesting of a good adhesion between both phases.

  14. Method of mechanical holding of cantilever chip for tip-scan high-speed atomic force microscope

    Fukuda, Shingo [Department of Physics, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Uchihashi, Takayuki; Ando, Toshio [Department of Physics, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Bio-AFM Frontier Research Center, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Core Research for Evolutional Science and Technology of the Japan Science and Technology Agency, 7 Goban-cho, Chiyoda-ku, Tokyo 102-0076 (Japan)

    2015-06-15

    In tip-scan atomic force microscopy (AFM) that scans a cantilever chip in the three dimensions, the chip body is held on the Z-scanner with a holder. However, this holding is not easy for high-speed (HS) AFM because the holder that should have a small mass has to be able to clamp the cantilever chip firmly without deteriorating the Z-scanner’s fast performance, and because repeated exchange of cantilever chips should not damage the Z-scanner. This is one of the reasons that tip-scan HS-AFM has not been established, despite its advantages over sample stage-scan HS-AFM. Here, we present a novel method of cantilever chip holding which meets all conditions required for tip-scan HS-AFM. The superior performance of this novel chip holding mechanism is demonstrated by imaging of the α{sub 3}β{sub 3} subcomplex of F{sub 1}-ATPase in dynamic action at ∼7 frames/s.

  15. Associative memory advantage in grapheme-colour synaesthetes compared to older, but not younger adults

    Gaby ePfeifer

    2014-07-01

    Full Text Available People with grapheme-colour synaesthesia perceive enriched experiences of colours in response to graphemes (letters, digits. In this study, we examined whether these synaesthetes show a generic associative memory advantage for stimuli that do not elicit a synaesthetic colour. We used a novel between group design (14 young synaesthetes, 14 young and 14 older adults with a self-paced visual associative learning paradigm and subsequent retrieval (immediate and delayed. Non-synaesthesia inducing, achromatic fractal pair-associates were manipulated in visual similarity (high and low and corresponded to high and low memory load conditions. The main finding was a learning and retrieval advantage of synaesthetes relative to older, but not to younger, adults. Furthermore the significance testing was supported with effect size measures and power calculations. Differences between synaesthetes and older adults were found during dissimilar pair (high memory load learning and retrieval at immediate and delayed stages. Moreover, we found a medium size difference between synaesthetes and young adults for similar pair (low memory load learning. Differences between young and older adults were also observed during associative learning and retrieval, but were of medium effect size coupled with low power. The results show a subtle associative memory advantage in synaesthetes for non-synaesthesia inducing stimuli, which can be detected against older adults. They also indicate that perceptual mechanisms (enhanced in synaesthesia, declining as part of the aging process can translate into a generic associative memory advantage, and may contribute to associative deficits associated with healthy aging.

  16. Microstructure, mechanical properties and microtexture of friction stir welded S690QL high yield steel

    Paillard, Pascal [Institut des Matériaux Jean Rouxel, UMR 6205, Polytech Nantes, Site de la Chantrerie, BP 50609, 44306 Nantes cedex 3 (France); Bertrand, Emmanuel, E-mail: emmanuel.bertrand@univ-nantes.fr [Institut des Matériaux Jean Rouxel, UMR 6205, Polytech Nantes, Site de la Chantrerie, BP 50609, 44306 Nantes cedex 3 (France); Allart, Marion; Benoit, Alexandre [Institut de Recherche Technologique Jules Verne, Chemin du Chaffault, 44340 Bouguenais (France); Ruckert, Guillaume [DCNS Research, Technocampus Ocean, 5 rue de l' Halbrane, 44340 Bouguenais (France)

    2016-12-15

    Two try-out campaigns of friction stir welding (FSW) were performed with different friction parameters to join S690QL high yield strength steel. The welds were investigated at macroscopic and microscopic scales using optical and electronic microscopy and microhardness mapping. Welds of the second campaign exhibit microstructures and mechanical properties in accordance with requirements for service use. Microtexture measurements were carried out in different zones of welds by electron backscattered diffraction (EBSD). It is shown that that texture of the bottom of the weld is similar to that of the base metal, suggesting a diffusion bonding mechanism. Finally, the mechanical properties (tensile strength, resilience, bending) were established on the most promising welds. It is shown that it is possible to weld this high yield strength steel using FSW process with satisfactory geometric, microstructural and mechanical properties. - Highlights: •1000 mm ∗ 400 mm ∗ 8 mm S690QL steel plates are joined by friction stir welding (FSW). •Maximum hardness is reduced by optimization of process parameters. •Various microstructures are formed but no martensite after process optimization. •Texture is modified in mechanically affected zones of the weld. •Texture in the bottom of the weld is preserved, suggesting diffusion bonding.

  17. Attractive mechanical properties of a lightweight highly sensitive bi layer thermistor: polycarbonate/organic molecular conductor

    Laukhina, E; Lebedev, V; Rovira, C; Laukhin, V; Veciana, J

    2016-01-01

    The paper covers some of the basic mechanical characteristics of a recently developed bi layer thermistor: polycarbonate/(001) oriented layer of organic molecular conductor α’-(BEDT-TTF) 2 I x Br 3-x , were BEDT-TTF=bis(ethylenedithio)tetrathiafulvalen. The nano and macro mechanical properties have been studied in order to use this flexible, low cost thermistor in sensing applications by proper way. The nano-mechanical properties of the temperature sensitive semiconducting layer of α’-(BEDT-TTF) 2 I x Br 3-x were tested using nanoindentation method. The value of Young's modulus in direction being perpendicular to the layer plan was found as 9.0 ±1.4 GPa. The macro mechanical properties of the thermistor were studied using a 5848 MicroTester. The tensile tests showed that basic mechanical characteristics of the thermistor are close to those of polycarbonate films. This indicates a good mechanical strength of the developed sensor. Therefore, the thermistor can be used in technologies that need to be instrumented with highly robustness lightweight low cost temperature sensors. The paper also reports synthetic details on fabricating temperature sensing e-textile. As the temperature control is becoming more and more important in biomedical technologies like healthcare monitoring, this work strongly contributes on the ongoing research on engineering sensitive conducting materials for biomedical applications. (paper)

  18. Fracture mechanical evaluation of high temperature structure and creep-fatigue defect assessment

    Park, Chang Gyu; Kim, Jong Bum; Lee, Jae Han

    2004-02-01

    This study proposed the evaluation procedure of high temperature structures from the viewpoint of fracture mechanics on the cylindrical structure applicable to the KALIMER, which is developed by KAERI. For the evaluation of structural integrity, linear and non-linear fracture mechanics parameters were analyzed. Parameters used in creep defect growth applicable to high temperature structure of liquid metal reactor and the evaluation codes with these parameters were analyzed. The evaluation methods of defect initiation and defect growth which were established in R5/R6 code(UK), JNC method (Japan) and RCC-MR A16(France) code were analyzed respectively. The evaluation procedure of leak before break applicable to KALIMER was preliminarily developed and proposed. As an application example of defect growth, the creep-fatigue defect growth on circumferential throughwall defect in high temperature cylindrical structure was evaluated by RCC-MR A16 and this application technology was established.

  19. Artificial neural networks in prediction of mechanical behavior of concrete at high temperature

    Mukherjee, A.; Nag Biswas, S.

    1997-01-01

    The behavior of concrete structures that are exposed to extreme thermo-mechanical loading is an issue of great importance in nuclear engineering. The mechanical behavior of concrete at high temperature is non-linear. The properties that regulate its response are highly temperature dependent and extremely complex. In addition, the constituent materials, e.g. aggregates, influence the response significantly. Attempts have been made to trace the stress-strain curve through mathematical models and rheological models. However, it has been difficult to include all the contributing factors in the mathematical model. This paper examines a new programming paradigm, artificial neural networks, for the problem. Implementing a feedforward network and backpropagation algorithm the stress-strain relationship of the material is captured. The neural networks for the prediction of uniaxial behavior of concrete at high temperature has been presented here. The results of the present investigation are very encouraging. (orig.)

  20. High-performance coupled poro-hydro-mechanical models to resolve fluid escape pipes

    Räss, Ludovic; Makhnenko, Roman; Podladchikov, Yury

    2017-04-01

    Field observations and laboratory experiments exhibit inelastic deformation features arising in many coupled settings relevant to geo-applications. These irreversible deformations and their specific patterns suggest a rather ductile or brittle mechanism, such as viscous creep or micro cracks, taking place on both geological (long) and human (short) timescales. In order to understand the underlying mechanisms responsible for these deformation features, there is a current need to accurately resolve the non-linearities inherent to strongly coupled physical processes. Among the large variety of modelling tools and softwares available nowadays in the community, very few are capable to efficiently solve coupled systems with high accuracy in both space and time and run efficiently on modern hardware. Here, we propose a robust framework to solve coupled multi-physics hydro-mechanical processes on very high spatial and temporal resolution in both two and three dimensions. Our software relies on the Finite-Difference Method and a pseudo-transient scheme is used to converge to the implicit solution of the system of poro-visco-elasto-plastic equations at each physical time step. The rheology including viscosity estimates for major reservoir rock types is inferred from novel lab experiments and confirms the ease of flow of sedimentary rocks. Our results propose a physical mechanism responsible for the generation of high permeability pathways in fluid saturated porous media and predict their propagation in rates observable on operational timescales. Finally, our software scales linearly on more than 5000 GPUs.

  1. High energy radiation effects on mechanical properties of butyl rubber compounds

    Pozenato, Cristina A.; Scagliusi, Sandra R.; Cardoso, Elisabeth C.L.; Lugao, Ademar B.

    2013-01-01

    The high energy radiation on butyl rubber compounds causes a number of chemical reactions that occur after initial ionization and excitation events. These reactions lead to changes in molecular mass of the polymer through scission and crosslinking of the molecules, being able to affect the physical and mechanical properties. Butyl rubber has excellent mechanical properties and oxidation resistance as well as low gas and water vapor permeability. Due to all these properties butyl rubber is widely used industrially and particularly in tires manufacturing. In accordance with various authors, the major effect of high energy, such as gamma rays in butyl rubber, is the yielding of free-radicals along with changes in mechanical properties. There were evaluated effects imparted from high energy radiation on mechanical properties of butyl rubber compounds, non-irradiated and irradiated with 25 kGy, 50 kGy, 150 kGy and 200 kGy. It was also observed a sharp reducing in stress rupture and elongation at break for doses higher than 50 kGy, pointing toward changes in polymeric chain along build-up of free radicals and consequent degradation. (author)

  2. Mechanical Integrity Issues at MCM-Cs for High Reliability Applications

    Morgenstern, H.A.; Tarbutton, T.J.; Becka, G.A.; Uribe, F.; Monroe, S.; Burchett, S.

    1998-01-01

    During the qualification of a new high reliability low-temperature cofired ceramic (LTCC) multichip module (MCM), two issues relating to the electrical and mechanical integrity of the LTCC network were encountered while performing qualification testing. One was electrical opens after aging tests that were caused by cracks in the solder joints. The other was fracturing of the LTCC networks during mechanical testing. Through failure analysis, computer modeling, bend testing, and test samples, changes were identified. Upon implementation of all these changes, the modules passed testing, and the MCM was placed into production

  3. Highly Conductive, Mechanically Robust, and Electrochemically Inactive TiC/C Nanofiber Scaffold for High-Performance Silicon Anode Batteries

    Yao, Yan; Huo, Kaifu; Hu, Liangbing; Liu, Nian; Cha, Judy J.; McDowell, Matthew T.; Chu, Paul K.; Cui, Yi

    2011-01-01

    Silicon has a high specific capacity of 4200 mAh/g as lithium-ion battery anodes, but its rapid capacity fading due to >300% volume expansion and pulverization presents a significant challenge for practical applications. Here we report a core-shell TiC/C/Si inactive/active nanocomposite for Si anodes demonstrating high specific capacity and excellent electrochemical cycling. The amorphous silicon layer serves as the active material to store Li+, while the inactive TiC/C nanofibers act as a conductive and mechanically robust scaffold for electron transport during the Li-Si alloying process. The core-shell TiC/C/Si nanocomposite anode shows ∼3000 mAh g-1 discharge capacity and 92% capacity retention after 100 charge/discharge cycles. The excellent cycling stability and high rate performance could be attributed to the tapering of the nanofibers and the open structure that allows facile Li ion transport and the high conductivity and mechanical stability of the TiC/C scaffold. © 2011 American Chemical Society.

  4. Highly Conductive, Mechanically Robust, and Electrochemically Inactive TiC/C Nanofiber Scaffold for High-Performance Silicon Anode Batteries

    Yao, Yan

    2011-10-25

    Silicon has a high specific capacity of 4200 mAh/g as lithium-ion battery anodes, but its rapid capacity fading due to >300% volume expansion and pulverization presents a significant challenge for practical applications. Here we report a core-shell TiC/C/Si inactive/active nanocomposite for Si anodes demonstrating high specific capacity and excellent electrochemical cycling. The amorphous silicon layer serves as the active material to store Li+, while the inactive TiC/C nanofibers act as a conductive and mechanically robust scaffold for electron transport during the Li-Si alloying process. The core-shell TiC/C/Si nanocomposite anode shows ∼3000 mAh g-1 discharge capacity and 92% capacity retention after 100 charge/discharge cycles. The excellent cycling stability and high rate performance could be attributed to the tapering of the nanofibers and the open structure that allows facile Li ion transport and the high conductivity and mechanical stability of the TiC/C scaffold. © 2011 American Chemical Society.

  5. High-speed infrared imaging for material characterization in experimental mechanics experiments

    Gagnon, Marc-André; Marcotte, Frédérick; Lagueux, Philippe; Farley, Vincent; Guyot, Éric; Morton, Vince

    2017-10-01

    Heat transfers are involved in many phenomena such as friction, tensile stress, shear stress and material rupture. Among the challenges encountered during the characterization of such thermal patterns is the need for both high spatial and temporal resolution. Infrared imaging provides information about surface temperature that can be attributed to the stress response of the material and breaking of chemical bounds. In order to illustrate this concept, tensile and shear tests were carried out on steel, aluminum and carbon fiber composite materials and monitored using high-speed (Telops FASTM2K) and high-definition (Telops HD-IR) infrared imaging. Results from split-Hopkinson experiments carried out on a polymer material at high strain-rate are also presented. The results illustrate how high-speed and high-definition infrared imaging in the midwave infrared (MWIR, 3 - 5 μm) spectral range can provide detailed information about the thermal properties of materials undergoing mechanical testing.

  6. Knowledge And Knowledge Management As A Competitive Advantage

    Diana Bratić

    2009-01-01

    Full Text Available In the modern business environment with high turbulence and complexity, an organization’s force to create and sustain competitive advantage lies in what it knows not what it owns. Establishment of a knowledge management in organization will ensure sustainable competitive advantage because the intellectual capital has become the primary bases of core competencies and the key to superior performance. The transition from industrial to knowledge society, effective use of knowledge is one of the deciding factors in the struggle for competitiveness because it will ensure the rationality, efficiency and flexibility in operations, and only through the realization of those graphics company can gain a competitive advantage on the market.

  7. Development of a High Temperature Antenna Pointing Mechanism for BepiColombo Planetary Orbiter

    Campo, Pablo; Barrio, Aingeru; Puente, Nicolas; Kyle, Robert

    2013-09-01

    BepiColombo is an ESA mission to Mercury its planetary orbiter (MPO) has two antenna pointing mechanism, High gain antenna pointing mechanism steers and points a large reflector which is integrated at system level by TAS-I Rome. Medium gain antenna (MGA) APM points a 1.5 m boom with a horn antenna. Both radiating elements exposed to sun fluxes as high as 10 solar constants without protections.The pointing mechanism is a major challenge as high performances are required in a harsh environment. It has required the development of new technologies, and components specially dedicated for the mission needs. Some of the state of the art required for the mission was achieved during the preparatory technology development activities [1]. However the number of critical elements involved, and the difficulties of some areas have required the continuation of the developments, and new research activities had to be launched in CD phase. Some of the major concerns and related areas of development are:- High temperature and long life requirements for the gearhead motors (up to 15500 equivalent APM revolutions, 19 million motor revolution)- Low thermal distortion of the mechanical chain, being at the same time insulating from external environment and interfaces (55 arcsec pointing error)- Low heat leak to the spacecraft (in the order of 50W per APM)- High precision position control, low microvibration noise and error stability in motion (16 arcsec/s)- High power radio frequency (18W in band Ka, 30 in X band) with phase stability for use in radio-science (3mm in Ka band, 5o in X band).- Wide range of motion (full 360o with end-stops)Currently HGA APM EQM azimuth and elevation stages are assembled and ready for test at actuator level.

  8. Mechanical ball-milling preparation of fullerene/cobalt core/shell nanocomposites with high electrochemical hydrogen storage ability.

    Bao, Di; Gao, Peng; Shen, Xiande; Chang, Cheng; Wang, Longqiang; Wang, Ying; Chen, Yujin; Zhou, Xiaoming; Sun, Shuchao; Li, Guobao; Yang, Piaoping

    2014-02-26

    The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today's development of hydrogen economy. Because of the special honeycomb structures and excellent physical and chemical characters, fullerenes have been extensively considered as ideal materials for hydrogen storage materials. To take the most advantage of its distinctive symmetrical carbon cage structure, we have uniformly coated C60's surface with metal cobalt in nanoscale to form a core/shell structure through a simple ball-milling process in this work. The X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, high-solution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDX) elemental mappings, and X-ray photoelectron spectroscopy (XPS) measurements have been conducted to evaluate the size and the composition of the composites. In addition, the blue shift of C60 pentagonal pinch mode demonstrates the formation of Co-C chemical bond, and which enhances the stability of the as-obtained nanocomposites. And their electrochemical experimental results demonstrate that the as-obtained C60/Co composites have excellent electrochemical hydrogen storage cycle reversibility and considerably high hydrogen storage capacities of 907 mAh/g (3.32 wt % hydrogen) under room temperature and ambient pressure, which is very close to the theoretical hydrogen storage capacities of individual metal Co (3.33 wt % hydrogen). Furthermore, their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible C60/Co↔C60/Co-Hx reaction is the dominant cycle process.

  9. Advantageous grain boundaries in iron pnictide superconductors

    Katase, Takayoshi; Ishimaru, Yoshihiro; Tsukamoto, Akira; Hiramatsu, Hidenori; Kamiya, Toshio; Tanabe, Keiichi; Hosono, Hideo

    2011-01-01

    High critical temperature superconductors have zero power consumption and could be used to produce ideal electric power lines. The principal obstacle in fabricating superconducting wires and tapes is grain boundaries—the misalignment of crystalline orientations at grain boundaries, which is unavoidable for polycrystals, largely deteriorates critical current density. Here we report that high critical temperature iron pnictide superconductors have advantages over cuprates with respect to these grain boundary issues. The transport properties through well-defined bicrystal grain boundary junctions with various misorientation angles (θGB) were systematically investigated for cobalt-doped BaFe2As2 (BaFe2As2:Co) epitaxial films fabricated on bicrystal substrates. The critical current density through bicrystal grain boundary (JcBGB) remained high (>1 MA cm−2) and nearly constant up to a critical angle θc of ∼9°, which is substantially larger than the θc of ∼5° for YBa2Cu3O7–δ. Even at θGB>θc, the decay of JcBGB was much slower than that of YBa2Cu3O7–δ. PMID:21811238

  10. Prediction of high airway pressure using a non-linear autoregressive model of pulmonary mechanics.

    Langdon, Ruby; Docherty, Paul D; Schranz, Christoph; Chase, J Geoffrey

    2017-11-02

    For mechanically ventilated patients with acute respiratory distress syndrome (ARDS), suboptimal PEEP levels can cause ventilator induced lung injury (VILI). In particular, high PEEP and high peak inspiratory pressures (PIP) can cause over distension of alveoli that is associated with VILI. However, PEEP must also be sufficient to maintain recruitment in ARDS lungs. A lung model that accurately and precisely predicts the outcome of an increase in PEEP may allow dangerous high PIP to be avoided, and reduce the incidence of VILI. Sixteen pressure-flow data sets were collected from nine mechanically ventilated ARDs patients that underwent one or more recruitment manoeuvres. A nonlinear autoregressive (NARX) model was identified on one or more adjacent PEEP steps, and extrapolated to predict PIP at 2, 4, and 6 cmH 2 O PEEP horizons. The analysis considered whether the predicted and measured PIP exceeded a threshold of 40 cmH 2 O. A direct comparison of the method was made using the first order model of pulmonary mechanics (FOM(I)). Additionally, a further, more clinically appropriate method for the FOM was tested, in which the FOM was trained on a single PEEP prior to prediction (FOM(II)). The NARX model exhibited very high sensitivity (> 0.96) in all cases, and a high specificity (> 0.88). While both FOM methods had a high specificity (> 0.96), the sensitivity was much lower, with a mean of 0.68 for FOM(I), and 0.82 for FOM(II). Clinically, false negatives are more harmful than false positives, as a high PIP may result in distension and VILI. Thus, the NARX model may be more effective than the FOM in allowing clinicians to reduce the risk of applying a PEEP that results in dangerously high airway pressures.

  11. Digital linear accelerator: The advantages for radiotherapy

    Andric, S.; Maksimovic, M.; Dekic, M.; Clark, T.

    1998-01-01

    Technical performances of Digital Linear Accelerator were presented to point out its advantages for clinical radiotherapy treatment. The accelerator installation is earned out at Military Medical Academy, Radiotherapy Department, by Medes and Elekta companies. The unit offers many technical advantages with possibility of introduction new conformal treatment techniques as stereotactic radiosurgery, total body and total skin irradiation. In the paper are underlined advantages in relation to running conventional accelerator units at Yugoslav radiotherapy departments, both from technical and medical point of view. (author)

  12. Establishing knowledge management for competitive advantage in an enterprise

    2012-01-01

    M.Inf. Enterprises are becoming more dependent on people than ever before and in the twenty first century, an enterprise's survival and success will highly depend on the ability to manage knowledge as a source for competitive advantage. This study is concerned with the establishment of a knowledge management program that will ensure sustainable competitive advantage within the enterprise. The main problem under investigation is to assess the importance of knowledge management within an ent...

  13. CREATING A CORPORATE ENTREPRENEURSHIP STRATEGY FOR COMPETITIVE ADVANTAGE

    ENGİNOĞLU, Didem; ARIKAN, Cenk Laçin

    2016-01-01

    Current competitive environment is rapidly changing. In today’s business environment, organizations are having an increasingly difficult time in creating competitive advantages. The main reason for this is the ease in contemporary business life for organizations to reach the same or very similar resources. Firms need innovation to create and sustain success and effectiveness. In such a highly competitive business life, the importance of creating competitive advantages for organizations based ...

  14. The kinetics and mechanism of bainite transformation in high strength steels

    Ali, A.; Bhadeshia, H.K.D.H.

    1993-01-01

    The kinetics and mechanism of bainite formation have been studied in high strength Fe-C-Si-Mn and Fe-C-Si-Ni steels using dilatometry, optical and transmission electron microscopy. In these silicon containing steels, carbide precipitation dies not accompany the growth of bainitic ferrite so that the mechanism of transformation can be readily interpreted. The work confirms that the volume fraction of bainite when the reaction stops, is far less that expected from equilibrium or para equilibrium considerations. In addition the bainite exhibits an invariant plane strain surface relief effect with a large shear component, and adopts a sheaf morphology. The results are demonstrated to be consistent with a displacive diffusion less transformation mechanism of bainite, in which the excess carbon is, subsequent to transformation, rejected into the residual austenite. (author)

  15. Aging mechanisms for concrete components of High-Level Waste storage tanks

    Kassir, M.; Bandyopadhyay, K.; Bush, S.; Mather, B.; Shewmon, P.; Streicher, M.; Thompson, B.; van Rooyen, D.; Weeks, J.

    1995-01-01

    The age-related degradation mechanisms which affect the concrete and the reinforcing steel in the high-level waste (HLW) storage tanks art evaluated with respect to their potential significance to the continued performance of the concrete, and am classified into non-significant and potentially significant. The identified potentially significant degradation mechanisms include the effects of elevated temperature, freezing and thawing, leaching of calcium hydroxide, aggressive chemical attack, and corrosion of the reinforcing steel. To the extent that available knowledge permits, these mechanisms are generically evaluated and quantified so that site-specific plans may be developed to verify whether significant degradation has occurred in the concrete, and, if so, to formulate mitigating measures to avoid further deterioration and possibly repair the degradation or pursue other management options

  16. Biomolecular Structure Information from High-Speed Quantum Mechanical Electronic Spectra Calculation.

    Seibert, Jakob; Bannwarth, Christoph; Grimme, Stefan

    2017-08-30

    A fully quantum mechanical (QM) treatment to calculate electronic absorption (UV-vis) and circular dichroism (CD) spectra of typical biomolecules with thousands of atoms is presented. With our highly efficient sTDA-xTB method, spectra averaged along structures from molecular dynamics (MD) simulations can be computed in a reasonable time frame on standard desktop computers. This way, nonequilibrium structure and conformational, as well as purely quantum mechanical effects like charge-transfer or exciton-coupling, are included. Different from other contemporary approaches, the entire system is treated quantum mechanically and neither fragmentation nor system-specific adjustment is necessary. Among the systems considered are a large DNA fragment, oligopeptides, and even entire proteins in an implicit solvent. We propose the method in tandem with experimental spectroscopy or X-ray studies for the elucidation of complex (bio)molecular structures including metallo-proteins like myoglobin.

  17. High Resolution Transmission Electron Microscope Observation of Zero-Strain Deformation Twinning Mechanisms in Ag

    Liu, L.; Wang, J.; Gong, S. K.; Mao, S. X.

    2011-04-01

    We have observed a new deformation-twinning mechanism using the high resolution transmission electron microscope in polycrystalline Ag films, zero-strain twinning via nucleation, and the migration of a Σ3{112} incoherent twin boundary (ITB). This twinning mechanism produces a near zero macroscopic strain because the net Burgers vectors either equal zero or are equivalent to a Shockley partial dislocation. This observation provides new insight into the understanding of deformation twinning and confirms a previous hypothesis: detwinning could be accomplished via the nucleation and migration of Σ3{112} ITBs. The zero-strain twinning mechanism may be unique to low staking fault energy metals with implications for their deformation behavior.

  18. A highly reliable cryogenic mixing pump with no mechanical moving parts

    Chen, W.; Niblick, A. L.

    2017-12-01

    This paper presents the design and preliminary test results of a novel cryogenic mixing pump based on magnetocaloric effect. The mixing pump is developed to enable long-term cryogenic propellant storage in space by preventing thermal stratification of cryogens in storage tanks. The mixing pump uses an innovative thermodynamic process to generate fluid jets to promote fluid mixing, eliminating the need for mechanical pumps. Its innovative mechanism uses a solid magnetocaloric material to alternately vaporize and condense the cryogen in the pumping chamber, and thus control the volume of the fluid inside the pumping chamber to produce pumping action. The pump is capable of self-priming and can generate a high-pressure rise. This paper discusses operating mechanism and design consideration of the pump, introduces the configuration of a brassboard cryogenic pump, and presents the preliminary test results of the pump with liquid nitrogen.

  19. Mechanical Properties of Wood Flour Reinforced High Density Polyethylene Composites with Basalt Fibers

    Guojun LU

    2014-12-01

    Full Text Available Basalt fibers (BFs were surface-treated with a vinyl triethoxy silane coupling agent to improve the mechanical properties of wood fiber-reinforced high density polyethylene (HDPE composites. Basalt fibers were characterized with SEM and FT-IR. The effects of the basalt fiber content and apparent morphology on the mechanical properties of the hybrid composites were investigated in this paper. The results show that the BF coated with the vinyl triethoxy silane coupling agent resulted in an improvement in mechanical properties due to the increased interfacial compatibility between the BF and HDPE. The flexural strength and impact properties significantly increased with 4 wt.% modified basalt fibers. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6441

  20. Dynamic mechanical analysis of compatibilizer effect on the mechanical properties of wood flour/high-density polyethylene composites

    Mehdi Behzad; Medhi Tajvidi; Ghanbar Ehrahimi; Robert H. Falk

    2004-01-01

    In this study, effect of MAPE (maleic anhydride polyethylene) as the compatibilizer on the mechanical properties of wood-flour polyethylene composites has been investigated by using Dynamic Mechanical Analysis (DMA). Composites were made at 25% and 50% by weight fiber contents and 1% and 2% compatibilizer respectively. Controls were also made at the same fiber contents...

  1. Mechanical Property and Its Comparison of Superalloys for High Temperature Gas Cooled Reactor

    Kim, Woo Gon; Kim, D. W.; Ryu, W. S.; Han, C. H.; Yoon, J. H.; Chang, J.

    2005-01-01

    Since structural materials for high temperature gas cooled reactor are used during long period in nuclear environment up to 1000 .deg. C, it is important to have good properties at elevated temperature such as mechanical properties (tensile, creep, fatigue, creep-fatigue), microstructural stability, interaction between metal and gas, friction and wear, hydrogen and tritium permeation, irradiation behavior, corrosion by impurity in He. Thus, in order to select excellent materials for the high temperature gas cooled reactor, it is necessary to understand the material properties and to gather the data for them. In this report, the items related to material properties which are needed for designing the high temperature gas cooled reactor were presented. Mechanical properties; tensile, creep, and fatigue etc. were investigated for Haynes 230, Hastelloy-X, In 617 and Alloy 800H, which can be used as the major structural components, such as intermediate heat exchanger (IHX), hot duct and piping and internals. Effect of He and irradiation on these structural materials was investigated. Also, mechanical properties; physical properties, tensile properties, creep and creep crack growth rate were compared for them, respectively. These results of this report can be used as important data to select superior materials for high temperature gas reactor

  2. Physico-mechanical properties of high performance concrete using different aggregates in presence of silica fume

    Salah A. Abo-El-Enein

    2014-04-01

    Full Text Available Heavy weight high performance concrete (HPC can be used when particular properties, such as high strength and good radiation shielding are required. Such concrete, using ilmenite and hematite coarse aggregates can significantly have higher specific gravities than those of concrete made with dolomite and air-cooled slag aggregates. Four different concrete mixes with the same cement content and different w/c ratios were designed using normal dolomite aggregate, air-cooled slag by-product and two different types of iron ore aggregates. High performance concrete (grade-M60 can be achieved using superplasticizer to reduce the water/cement ratio; the effect of SF on the performance of concrete was studied by addition of 10% silica fume to the total cement content. The physico-mechanical properties of coarse aggregates and hardened concrete were studied. The results show that, Ilmenite coarse aggregate gives higher physical and mechanical properties than the other aggregates. Also, addition of 10% silica fume developed a stronger and a denser interfacial transition zone (ITZ between concrete particles and the cement matrix. Crushed air-cooled slag can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with crushed hematite and ilmenite. Heavy density concrete made with fine aggregates of ilmenite and air-cooled slag are expected to be suitable as shielding materials to attenuate gamma rays.

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

    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.

  4. Corrosion mechanism of 13Cr stainless steel in completion fluid of high temperature and high concentration bromine salt

    Liu, Yan; Xu, Lining; Lu, Minxu; Meng, Yao; Zhu, Jinyang; Zhang, Lei

    2014-01-01

    Highlights: • The corrosion behavior of 13Cr steel exposed to bromine salt completion fluid containing high concentration bromine ions was investigated. • There are passive circles around pits on the 13Cr steel surface after 7 d of exposure. • Macroscopic galvanic corrosion formed between the passive halo and the pit. • The mechanism of pitting corrosion on 13Cr stainless steel exposed to heavy bromine brine was established. - Abstract: A series of corrosion tests of 13Cr stainless steel were conducted in a simulated completion fluid environment of high temperature and high concentration bromine salt. Corrosion behavior of specimens and the component of corrosion products were investigated by means of scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The results indicate that 13Cr steel suffers from severe local corrosion and there is always a passive halo around every pit. The formation mechanism of the passive halo is established. OH − ligand generates and adsorbs in a certain scale because of abundant OH − on the surface around the pits. Passive film forms around each pit, which leads to the occurrence of passivation in a certain region. Finally, the dissimilarities in properties and morphologies of regions, namely the pit and its corresponding passive halo, can result in different corrosion sensitivities and may promote the formation of macroscopic galvanic pairs

  5. Studies on Fusion Welding of High Nitrogen Stainless Steel: Microstructure, Mechanical and corrosion Behaviour

    Mohammed, Raffi; Srinivasa Rao, K.; Madhusudhan Reddy, G.

    2018-03-01

    An attempt has been made in the present investigation to weld high nitrogen steel of 5mm thick plates using various process i.e., shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW) and autogenous electron beam welding (EBW) process. Present work is aimed at studying the microstructural changes and its effects on mechanical properties and corrosion resistance. Microstructure is characterized by optical, scanning electron microscopy and electron back scattered diffraction technique. Vickers hardness, tensile properties, impact toughness and face bend ductility testing of the welds was carried out. Pitting corrosion resistance of welds was determined using potentio-dynamic polarization testing in 3.5%NaCl solution. Results of the present investigation established that SMA welds made using Cr-Mn-N electrode were observed to have a austenite dendritic grain structure in the weld metal and is having poor mechanical properties but good corrosion resistance. GTA welds made using 18Ni (MDN 250) filler wire were observed to have a reverted austenite in martensite matrix of the weld metal and formation of unmixed zone at the fusion boundary which resulted in better mechanical properties and poor corrosion resistance. Fine grains and uniform distribution of delta ferrite in the austenite matrix and narrow width of weld zone are observed in autogeneous electron beam welds. A good combination of mechanical properties and corrosion resistance was achieved for electron beam welds of high nitrogen steel when compared to SMA and GTA welds.

  6. Mechanical versus kinematical shortening reconstructions of the Zagros High Folded Zone (Kurdistan region of Iraq)

    Frehner, Marcel; Reif, Daniel; Grasemann, Bernhard

    2012-06-01

    This paper compares kinematical and mechanical techniques for the palinspastic reconstruction of folded cross sections in collision orogens. The studied area and the reconstructed NE-SW trending, 55.5 km long cross section is located in the High Folded Zone of the Zagros fold-and-thrust belt in the Kurdistan region of Iraq. The present-day geometry of the cross section has been constructed from field as well as remote sensing data. In a first step, the structures and the stratigraphy are simplified and summarized in eight units trying to identify the main geometric and mechanical parameters. In a second step, the shortening is kinematically estimated using the dip domain method to 11%-15%. Then the same cross section is used in a numerical finite element model to perform dynamical unfolding simulations taking various rheological parameters into account. The main factor allowing for an efficient dynamic unfolding is the presence of interfacial slip conditions between the mechanically strong units. Other factors, such as Newtonian versus power law viscous rheology or the presence of a basement, affect the numerical simulations much less strongly. If interfacial slip is accounted for, fold amplitudes are reduced efficiently during the dynamical unfolding simulations, while welded layer interfaces lead to unrealistic shortening estimates. It is suggested that interfacial slip and decoupling of the deformation along detachment horizons is an important mechanical parameter that controlled the folding processes in the Zagros High Folded Zone.

  7. Comparison of mechanical concepts for $Nb_3Sn$ high field accelerator magnets

    AUTHOR|(CDS)2084469; Peter, Schmolz

    Several magnets using Nb$_{3}$Sn as conductor are currently developed at CERN; these magnets are either slated for future updates of the LHC or for research purposes relating to future accelerators. The mechanical structure is one of the challenging aspects of superconducting high-field magnets. The main purpose of the mechanical structure is to keep the coils in compression till the emergence of the highest electromagnetic forces that are developed in the ultimate field of the magnet. Any loss of pre-compression during the magnet’s excitation would cause too large deformation of the coil and possibly a quench in the conductor owing to relative movements of strands in contact associated with excessive local heat release. However, too high pre-compression would overstrain the conductor and thereby limit the performance of the magnet. This thesis focuses on the mechanical behaviour of three of these magnets. All of them are based on different mechanical designs, “bladder and key” and “collar-based”, ...

  8. Mechanical alloying and self-propagating high-temperature synthesis of stable icosahedral quasicrystals

    Bokhonov, B.B.

    2008-01-01

    The phase evolution of the mechanically alloyed ternary 63%Al + 25%Cu + 12%Fe and 65%Al + 20%Cu + 15%Fe powder mixtures with milling time has been studied by X-ray diffraction method. It was found that an icosahedral quasicrystalline phase was formed directly during high-energy ball milling of the Al-Cu-Fe mixtures. The X-ray and scanning electron microscopic investigations demonstrated the possibility to use self-propagating high-temperature synthesis (SHS) in combination with preliminary mechanical activation for the synthesis of stable icosahedral quasicrystals. The typical morphology of the Al 63 Cu 25 Fe 12 icosahedral quasicrystals formed in the SHS process is a pentagonal dodecahedron with a size of 3-5 mm. The phase composition of the SHS products depends on the time of preliminary mechanical activation. The content of cubic intermetallic phase in SHS products increases with the time of preliminary mechanical activation of the 63%Al + 25%Cu + 12%Fe powder mixtures

  9. Effects of carbon content on high-temperature mechanical and thermal fatigue properties of high-boron austenitic steels

    Xiang Chen

    2016-01-01

    Full Text Available High-temperature mechanical properties of high-boron austenitic steels (HBASs were studied at 850 °C using a dynamic thermal-mechanical simulation testing machine. In addition, the thermal fatigue properties of the alloys were investigated using the self-restraint Uddeholm thermal fatigue test, during which the alloy specimens were cycled between room temperature and 800°C. Stereomicroscopy and scanning electron microscopy were used to study the surface cracks and cross-sectional microstructure of the alloy specimens after the thermal fatigue tests. The effects of carbon content on the mechanical properties at room temperature and high-temperature as well as thermal fatigue properties of the HBASs were also studied. The experimental results show that increasing carbon content induces changes in the microstructure and mechanical properties of the HBASs. The boride phase within the HBAS matrix exhibits a round and smooth morphology, and they are distributed in a discrete manner. The hardness of the alloys increases from 239 (0.19wt.% C to 302 (0.29wt.% C and 312 HV (0.37wt.% C; the tensile yield strength at 850 °C increases from 165.1 to 190.3 and 197.1 MPa; and the compressive yield strength increases from 166.1 to 167.9 and 184.4 MPa. The results of the thermal fatigue tests (performed for 300 cycles from room temperature to 800 °C indicate that the degree of thermal fatigue of the HBAS with 0.29wt.% C (rating of 2–3 is superior to those of the alloys with 0.19wt.% (rating of 4–5 and 0.37wt.% (rating of 3–4 carbon. The main cause of this difference is the ready precipitation of M23(C,B6-type borocarbides in the alloys with high carbon content during thermal fatigue testing. The precipitation and aggregation of borocarbide particles at the grain boundaries result in the deterioration of the thermal fatigue properties of the alloys.

  10. High-quality vertical light emitting diodes fabrication by mechanical lift-off technique

    Tu, Po-Min; Hsu, Shih-Chieh; Chang, Chun-Yen

    2011-10-01

    We report the fabrication of mechanical lift-off high quality thin GaN with Hexagonal Inversed Pyramid (HIP) structures for vertical light emitting diodes (V-LEDs). The HIP structures were formed at the GaN/sapphire substrate interface under high temperature during KOH wet etching process. The average threading dislocation density (TDD) was estimated by transmission electron microscopy (TEM) and found the reduction from 2×109 to 1×108 cm-2. Raman spectroscopy analysis revealed that the compressive stress of GaN epilayer was effectively relieved in the thin-GaN LED with HIP structures. Finally, the mechanical lift-off process is claimed to be successful by using the HIP structures as a sacrificial layer during wafer bonding process.

  11. Effect of grain size on the high temperature mechanical properties of type 316LN stainless steel

    Kim, D. W.; Lee, Y. S.; Ryu, W. S.; Jang, J. S.; Kim, S. H.; Kim, W. G.; Cho, H. D.; Han, C. H

    2001-02-01

    Nitrogen increases the high temeprature mechanical properties and decreases grain size. The effect of nitrogen on the high temperature mechanical properties was investigated in the viewpoint of grain size. Tensile strength increases with the decrease of grain size and agrees with the Hall-Petch relationship. Effect of grain size on the low cycle fatigue life properties were investigated as measuring the fatigue life from the results which had been obtained by the constant strain rate and various strain range. There was no effect on the low cycle fatigue properties by the grain size. The time to rupture decreased with the increase of grain size. The steady state creep rate decreased to a minimum and then increased as the grain size increased. This result agrees with the result predicted from Garofalo equation. The rupture elongation at the intermediate grain size showed a minimum due to the cavity formed easily by carbide precipitates in the grain boundaries.

  12. Investigation of corrosion resistance of alloys with high mechanical characteristics in some environments of food industry

    Tremoureux, Yves

    1978-01-01

    This research thesis aimed at improving knowledge in the field of stress-free corrosion of alloys with high mechanical characteristics in aqueous environments, at highlighting some necessary aspects of their behaviour during cleaning or disinfection, and at selecting alloys which possess a good stress-free corrosion resistance in view of a later investigation of their stress corrosion resistance. After a presentation of the metallurgical characteristics of high mechanical strength alloys and the report of a bibliographical study on corrosion resistance of these alloys, the author presents and discusses the results obtained in the study of a possible migration of metallic ions in a milk product which is submitted to a centrifugation, and of the corrosion resistance of selected alloys with respect to the different media they will be in contact with during ultra-centrifugation. The following alloys have been used in this research: Marval 18, Marphynox, Marval X12, 17-4PH steel, Inconel 718 [fr

  13. Variation of Mechanical Properties of High RRR And Reactor Grade Niobium With Heat Treatments

    Ganapati Myneni; H. Umezawa

    2003-06-01

    Superconducting rf cavities used as accelerating structures in particle accelerators are made from high purity niobium with residual resistance ratios greater than 250. Reactor grade niobium is also used to make wave-guide and/or end group components for these accelerating structures. The major impurities in this type of niobium are interstitially dissolved gases such as hydrogen, nitrogen, and oxygen in addition to carbon. After fabricating the niobium accelerating structures, they are subjected to heat treatments for several hours in vacuum at temperatures of up to 900 C for degassing hydrogen or up to 1400 C for improving the thermal conductivity of niobium considerably. These heat treatments are affecting the mechanical properties of niobium drastically. In this paper the variation of the mechanical properties of high purity and reactor grade niobium with heat treatments in a vacuum of {approx} 10{sup -6} Torr and temperatures from 600 C to 1250 C for periods of 10 to 6 hours are presented.

  14. ASM Inaugural Lecture 2009: High temperature superconductors: Materials, mechanisms and applications

    Roslan Abdul Shukor

    2009-01-01

    A surprising variety of new superconducting materials has been discovered in recent years. Many compounds with light elements such as fullerenes, oxides, borides, nitrides, some organic materials and also heavy fermions have been found to superconductor at various temperatures. Hitherto, superconductors have proven to be highly varied in composition but elusive and mysterious. The juxtaposition of superconductivity and magnetism at the nano scale in some of these new materials has paved the way to a rich and exciting new field in condensed matter and materials research. An overview of superconductor research in Malaysian institutions is presented in this paper. Some of the new superconducting materials and their possible mechanisms, conventional and exotic, are presented. The possible role of lattice vibrations in the mechanisms of high temperature superconductivity and the study of this via acoustic methods are discussed. Frozen flux superconductors in a nano magnet-superconductor hybrid system are also discussed. (author)

  15. The nano-mechanical signature of Ultra High Performance Concrete by statistical nanoindentation techniques

    Sorelli, Luca; Constantinides, Georgios; Ulm, Franz-Josef; Toutlemonde, Francois

    2008-01-01

    Advances in engineering the microstructure of cementitious composites have led to the development of fiber reinforced Ultra High Performance Concretes (UHPC). The scope of this paper is twofold, first to characterize the nano-mechanical properties of the phases governing the UHPC microstructure by means of a novel statistical nanoindentation technique; then to upscale those nanoscale properties, by means of continuum micromechanics, to the macroscopic scale of engineering applications. In particular, a combined investigation of nanoindentation, scanning electron microscope (SEM) and X-ray Diffraction (XRD) indicates that the fiber-matrix transition zone is relatively defect free. On this basis, a four-level multiscale model with defect free interfaces allows to accurately determine the composite stiffness from the measured nano-mechanical properties. Besides evidencing the dominant role of high density calcium silicate hydrates and the stiffening effect of residual clinker, the suggested model may become a useful tool for further optimizing cement-based engineered composites

  16. Comparative Advantages of Spin-off Firms: An Evolutionary Perspective

    Bilgehan Uzunca

    2011-11-01

    Full Text Available As predicted by evolutionary economics, historical antecedents matter when it comes to the relationship between survival of entrants and organizational capabilities. Spinoff firms provide an exemplary case of such relationship where the founders’ pre-entry capabilities that are inherited from the parent firm increases their survival chances. Looking closer and deeper to the evolutionary spinoff success mechanisms, I examine three specific genetic features which make spinoff firms more advantageous compared to other entrants; namely 1 Genotype: Transfer of blueprint, 2 Phenotype: Organizational learning, and 3 Memes: Informal relations and social capital. A detailed theoretical analysis of each mechanism prevails how they function and provide sustainable competitive advantage to spinoff firms. Testable hypotheses are provided about each mechanism.

  17. A fracture mechanics study of tungsten failure under high heat flux loads

    Li, Muyuan

    2015-01-01

    The performance of fusion devices is highly dependent on plasma-facing components. Tungsten is the most promising candidate material for armors in plasma-facing components in ITER and DEMO. However, the brittleness of tungsten below the ductile-to-brittle transition temperature is very critical to the reliability of plasma-facing components. In this work, thermo-mechanical and fracture behaviors of tungsten are predicted numerically under fusion relevant thermal loadings.

  18. Welding of nickel free high nitrogen stainless steel: Microstructure and mechanical properties

    Raffi Mohammed; G. Madhusudhan Reddy; K. Srinivasa Rao

    2017-01-01

    High nitrogen stainless steel (HNS) is a nickel free austenitic stainless steel that is used as a structural component in defence applications for manufacturing battle tanks as a replacement of the existing armour grade steel owing to its low cost, excellent mechanical properties and better corrosion resistance. Conventional fusion welding causes problems like nitrogen desorption, solidification cracking in weld zone, liquation cracking in heat affected zone, nitrogen induced porosity and poo...

  19. Dynamic tensile behaviour and deformational mechanism of C5191 phosphor bronze under high strain rates deformation

    Hu, Dao-chun [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Taizhou Vocational & Technical College, Taizhou 318000 (China); Chen, Ming-he, E-mail: meemhchen@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Lei; Cheng, Hu [College of Mechanical Engineering, Taizhou University, Taizhou 318000 (China)

    2016-01-01

    High speed stamping process is used to high strength and high electrical conductivity phosphor bronze with extremely high strain rates more than 10{sup 3} s{sup −1}. This study on the dynamic tensile behaviour and deformational mechanism is to optimise the high speed stamping processes and improve geometrical precision in finished products. Thus, the tensile properties and deformation behaviour of C5191 phosphor bronze under quasi-static tensile condition at a strain rate of 0.001 s{sup −1} by electronic universal testing machine, and dynamic tensile condition at strain rate of 500, 1000 and 1500 s{sup −1} by split Hopkinson tensile bar (SHTB) apparatus were studied. The effects of strain rate and the deformation mechanism were investigated by means of SEM and TEM. The results showed that the yield strength and tensile strength of C5191 phosphor bronze under high strain rates deformation increased by 32.77% and 11.07% respectively compared with quasi-static condition, the strain hardening index increases from 0.075 to 0.251, and the strength of the material strain rates sensitivity index change from 0.005 to 0.022, which presented a clear sensitive to strain rates. Therefore, it is claimed that the dominant deformation mechanism was changed by the dislocation motion under different strain rates, and the ability of plastic deformation of C5191 phosphor bronze increased due to the number of movable dislocations increased significantly, started multi-line slip, and the soft effect of adiabatic temperature rise at the strain rate ranging from 500 to 1500 s{sup −1}.

  20. Analysis of yield advantage in mixed cropping

    Ranganathan, R.

    1993-01-01

    It has long been recognized that mixed cropping can give yield advantages over sole cropping, but methods that can identify such yield benefits are still being developed. This thesis presents a method that combines physiological and economic principles in the evaluation of yield advantage.

  1. Competitive advantage, what does it really mean?

    dr. Haijing de Haan; Hongjue Yan

    2013-01-01

    Competitive advantage is probably the most popular business concept today (Mooney, 2007). This article aims to investigate critically the discourse on competitive advantage, as expressed by business literature, by locating its meanings in the public higher education sector. This research reveals

  2. Strategic Positioning for Sustainable Competitive Advantage: An ...

    Organizational learning is increasingly being considered as one of the fundamental sources of competitive advantage within the context of strategic management. However, most literature has not clearly linked organizational learning with sustainable competitive advantage. This paper, therefore, explores and discusses the ...

  3. Analisis Dampak Servant Leadership Terhadap Competitive Advantage

    Oktavia, Pek Nike

    2014-01-01

    Penelitian ini bertujuan untuk mengetahui apakah terdapat dampak antara Servant Leadership terhadap Competitve Advantage, Employee Empowerment dan Organizational Learning. Variabel Servant Leadership diukur dari lima indikator, yaitu altruistic calling, emotional healing, wisdom, persuasive mapping, dan organizational stewardship. Variabel Competitive Advantage diukur dari lima indikator, yaitu price/cost, quality, delivery dependability, time to market, dan product innovation. Variabel Emplo...

  4. Mechanistic Basis of Cocrystal Dissolution Advantage.

    Cao, Fengjuan; Amidon, Gordon L; Rodríguez-Hornedo, Naír; Amidon, Gregory E

    2018-01-01

    Current interest in cocrystal development resides in the advantages that the cocrystal may have in solubility and dissolution compared with the parent drug. This work provides a mechanistic analysis and comparison of the dissolution behavior of carbamazepine (CBZ) and its 2 cocrystals, carbamazepine-saccharin (CBZ-SAC) and carbamazepine-salicylic acid (CBZ-SLC) under the influence of pH and micellar solubilization. A simple mathematical equation is derived based on the mass transport analyses to describe the dissolution advantage of cocrystals. The dissolution advantage is the ratio of the cocrystal flux to drug flux and is defined as the solubility advantage (cocrystal to drug solubility ratio) times the diffusivity advantage (cocrystal to drug diffusivity ratio). In this work, the effective diffusivity of CBZ in the presence of surfactant was determined to be different and less than those of the cocrystals. The higher effective diffusivity of drug from the dissolved cocrystals, the diffusivity advantage, can impart a dissolution advantage to cocrystals with lower solubility than the parent drug while still maintaining thermodynamic stability. Dissolution conditions where cocrystals can display both thermodynamic stability and a dissolution advantage can be obtained from the mass transport models, and this information is useful for both cocrystal selection and formulation development. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  5. Chemical influence on the hydro-mechanical behaviour of high-density bentonite

    Castellanos, E.; Romero, E.; Lioret, A. [Technical Univ. of Catalonia UPC, Barcelona (Spain); Musso, G. [Politecnico di Torino, Torino (Italy)

    2005-07-01

    In radioactive waste disposal schemes, during the operational period of clay barriers, solute transport an d thermal gradients may alter the solute concentration of pore water. These induced changes have important consequences on hydro-mechanical properties and microstructural alterations (mineral composition and pore size distribution changes) of the clay barrier. Chemically induced changes originated by different imbibition fluids and soil mineral compositions have been a subject with a long research tradition. These researches have been mainly focused on the behaviour of reconstituted soils starting from slurry and saturated wit h saline solutions at elevated concentrations, where hydro-mechanical changes (soil compressibility and water permeability changes) are clearly detected. In contrast, available information concerning the response of high-density clays subjected to chemically induced actions with a wide range of pore solution concentrations is very limited in spite of its practical relevance to environmental geotechnics. This situation has been caused, at least in part, by the difficulties in detecting important hydro-mechanical changes when clays with low water storage capacity have been used. Nevertheless, this paper will demonstrate that even in the case of high-density fabrics, considerable changes can be observed when high-activity clays (bentonites) are imbibed with different pore fluid compositions. (authors)

  6. Seismic performance evaluation of high natural frequency mechanical structure from the viewpoint of energy balance

    Minagawa, Keisuke; Fujita, Satoshi; Endo, Rokuro; Amemiya, Mitsuhiko

    2009-01-01

    In this study, vibration characteristics of mechanical structure having high natural frequency are investigated from the viewpoint of energy balance. Mechanical structures having high natural frequency in a nuclear power plant are generally designed statically and elastically. However it has been reported that fracture of ordinary piping is produced not by momentary large load but by cumulative fatigue damage. Therefore it is very important to grasp seismic performance dynamically by considering cyclic load. This paper deals with an investigation regarding seismic performance evaluation of high natural frequency mechanical structure. The energy balance equation that is one of valid methods for structural calculation is applied through the investigation. The main feature of the energy balance equation is that it explains accumulated information of motion. Therefore the energy balance equation is adequate for the investigation of the influence of cumulative load such as seismic response. In this paper, vibration experiment and simulation using sinusoidal waves and artificial seismic waves were examined in order to investigate relationship between natural frequency of structure and energy. As a result, we found that input energy decreases with an increase in the natural frequency. (author)

  7. A high throughput array microscope for the mechanical characterization of biomaterials

    Cribb, Jeremy; Osborne, Lukas D.; Hsiao, Joe Ping-Lin; Vicci, Leandra; Meshram, Alok; O'Brien, E. Tim; Spero, Richard Chasen; Taylor, Russell; Superfine, Richard

    2015-02-01

    In the last decade, the emergence of high throughput screening has enabled the development of novel drug therapies and elucidated many complex cellular processes. Concurrently, the mechanobiology community has developed tools and methods to show that the dysregulation of biophysical properties and the biochemical mechanisms controlling those properties contribute significantly to many human diseases. Despite these advances, a complete understanding of the connection between biomechanics and disease will require advances in instrumentation that enable parallelized, high throughput assays capable of probing complex signaling pathways, studying biology in physiologically relevant conditions, and capturing specimen and mechanical heterogeneity. Traditional biophysical instruments are unable to meet this need. To address the challenge of large-scale, parallelized biophysical measurements, we have developed an automated array high-throughput microscope system that utilizes passive microbead diffusion to characterize mechanical properties of biomaterials. The instrument is capable of acquiring data on twelve-channels simultaneously, where each channel in the system can independently drive two-channel fluorescence imaging at up to 50 frames per second. We employ this system to measure the concentration-dependent apparent viscosity of hyaluronan, an essential polymer found in connective tissue and whose expression has been implicated in cancer progression.

  8. Salvador Dalí's paintings to introduce Quantum Mechanics concepts in High School

    Rúbia de Fátima Antunes Martins Fernandes

    2017-08-01

    Full Text Available A few papers have presented results of teaching Quantum Mechanics in High School. As a high abstraction level is demanded, it is necessary to reconsider theoretical assumptions, approaches and methodologies, in order to reduce difficulties in its insertion. This paper presents the achievements of a research, which is a didactic proposal for High School comprising discussions about Quantum Mechanics, involving elements that relate Physics and some paintings of Salvador Dalí. Embracing the relations between Physics and Art allows us to approach and express the relations between scientific education and culture with alternative ways to enrich the knowledge meaning, also aiming to provide students with a broader view about the scientific knowledge construction in an intelligent dialogue with the world.  To do so, the proposal presents an operative methodology, approaching science as a historical and social knowledge to teach quantum mechanics, and it aims to make the student able to hypothesize, conceptualize, situate scientific explanations in time, in short, operate according to the provided tools. Working with the ways in which Physics, introduced as a cultural component, influences the interpretations of macro and microscopic phenomena and contributes to the understanding of Modern Physics, part of twentieth-century Physics. Therefore, adding cultural elements to Physics world seems to be increasingly necessary, as it seems to resignify it by rehumanizing its knowledge. In addition, using the historical context seems to give us a greater extensiveness to knowledge, since it also starts being part of a broader culture, beyond its scientific meaning.

  9. Soil mechanical stresses in high wheel load agricultural field traffic: a case study

    Lamandé, Mathieu; Schjønning, Per

    2017-01-01

    highly skewed. Across tyres, the maximum stress in the contact area correlated linearly with, but was much higher than, the mean ground pressure. For each of the three soil depths, the maximum stresses under the tyres were significantly correlated with the wheel load, but not with other loading......Subsoil compaction is a serious long-term threat to soil functions. Only a few studies have quantified the mechanical stresses reaching deep subsoil layers for modern high wheel load machinery. In the present study we measured the vertical stresses in the tyre–soil contact area and at 0.3, 0...

  10. Molecular mechanisms regulating oxygen transport and consumption in high altitude and hibernating mammals

    Revsbech, Inge Grønvall

    2016-01-01

    The aim of this thesis is to broaden the knowledge of molecular mechanisms of adjustment in oxygen (O2) uptake, conduction, delivery and consumption in mammals adapted to extreme conditions. For this end, I have worked with animals living at high altitude as an example of environmental hypoxia...... of the repeatedly found adaptive traits in animals living at high altitude and in hibernating mammals during hibernation compared with the active state. Factors that affect O2 affinity of Hb include temperature, H+/CO2 via the Bohr effect as well as Cl- and organic phosphates, in mammals mainly 2...

  11. Inverse methods for the mechanical characterization of materials at high strain rates

    Casas-Rodriguez J.P.

    2012-08-01

    Full Text Available Mechanical material characterization represents a research challenge. Furthermore, special attention is directed to material characterization at high strain rates as the mechanical properties of some materials are influenced by the rate of loading. Diverse experimental techniques at high strain rates are available, such as the drop-test, the Taylor impact test or the Split Hopkinson pressure bar among others. However, the determination of the material parameters associated to a given mathematical constitutive model from the experimental data is a complex and indirect problem. This paper presents a material characterization methodology to determine the material parameters of a given material constitutive model from a given high strain rate experiment. The characterization methodology is based on an inverse technique in which an inverse problem is formulated and solved as an optimization procedure. The input of the optimization procedure is the characteristic signal from the high strain rate experiment. The output of the procedure is the optimum set of material parameters determined by fitting a numerical simulation to the high strain rate experimental signal.

  12. Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds

    Wang, Zhandong

    2017-11-28

    Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.

  13. High-Temperature Performance and Multiscale Damage Mechanisms of Hollow Cellulose Fiber-Reinforced Concrete

    Liping Guo

    2016-01-01

    Full Text Available Spalling resistance properties and their damage mechanisms under high temperatures are studied in hollow cellulose fiber-reinforced concrete (CFRC used in tunnel structures. Measurements of mass loss, relative dynamic elastic modulus, compressive strength, and splitting tensile strength of CFRC held under high temperatures (300, 600, 800, and 1050°C for periods of 2.5, 4, and 5.5 h were carried out. The damage mechanism was analyzed using scanning electron microscopy, mercury intrusion porosimetry, thermal analysis, and X-ray diffraction phase analysis. The results demonstrate that cellulose fiber can reduce the performance loss of concrete at high temperatures; the effect of holding time on the performance is more noticeable below 600°C. After exposure to high temperatures, the performance of ordinary concrete deteriorates faster and spalls at 700–800°C; in contrast, cellulose fiber melts at a higher temperature, leaving a series of channels in the matrix that facilitate the release of the steam pressure inside the CFRC. Hollow cellulose fibers can thereby slow the damage caused by internal stress and improve the spalling resistance of concrete under high temperatures.

  14. Unraveling the structure and chemical mechanisms of highly oxygenated intermediates in oxidation of organic compounds

    Wang, Zhandong; Popolan-Vaida, Denisia M.; Chen, Bingjie; Moshammer, Kai; Mohamed, Samah; Wang, Heng; Sioud, Salim; Raji, Misjudeen; Kohse-Hö inghaus, Katharina; Hansen, Nils; Dagaut, Philippe; Leone, Stephen R.; Sarathy, Mani

    2017-01-01

    Decades of research on the autooxidation of organic compounds have provided fundamental and practical insights into these processes; however, the structure of many key autooxidation intermediates and the reactions leading to their formation still remain unclear. This work provides additional experimental evidence that highly oxygenated intermediates with one or more hydroperoxy groups are prevalent in the autooxidation of various oxygenated (e.g., alcohol, aldehyde, keto compounds, ether, and ester) and nonoxygenated (e.g., normal alkane, branched alkane, and cycloalkane) organic compounds. These findings improve our understanding of autooxidation reaction mechanisms that are routinely used to predict fuel ignition and oxidative stability of liquid hydrocarbons, while also providing insights relevant to the formation mechanisms of tropospheric aerosol building blocks. The direct observation of highly oxygenated intermediates for the autooxidation of alkanes at 500–600 K builds upon prior observations made in atmospheric conditions for the autooxidation of terpenes and other unsaturated hydrocarbons; it shows that highly oxygenated intermediates are stable at conditions above room temperature. These results further reveal that highly oxygenated intermediates are not only accessible by chemical activation but also by thermal activation. Theoretical calculations on H-atom migration reactions are presented to rationalize the relationship between the organic compound’s molecular structure (n-alkane, branched alkane, and cycloalkane) and its propensity to produce highly oxygenated intermediates via extensive autooxidation of hydroperoxyalkylperoxy radicals. Finally, detailed chemical kinetic simulations demonstrate the influence of these additional reaction pathways on the ignition of practical fuels.

  15. Experimental Investigation into Corrosion Effect on Mechanical Properties of High Strength Steel Bars under Dynamic Loadings

    Hui Chen

    2018-01-01

    Full Text Available The tensile behaviors of corroded steel bars are important in the capacity evaluation of corroded reinforced concrete structures. The present paper studies the mechanical behavior of the corroded high strength reinforcing steel bars under static and dynamic loading. High strength reinforcing steel bars were corroded by using accelerated corrosion methods and the tensile tests were carried out under different strain rates. The results showed that the mechanical properties of corroded high strength steel bars were strain rate dependent, and the strain rate effect decreased with the increase of corrosion degree. The decreased nominal yield and ultimate strengths were mainly caused by the reduction of cross-sectional areas, and the decreased ultimate deformation and the shortened yield plateau resulted from the intensified stress concentration at the nonuniform reduction. Based on the test results, reduction factors were proposed to relate the tensile behaviors with the corrosion degree and strain rate for corroded bars. A modified Johnson-Cook strength model of corroded high strength steel bars under dynamic loading was proposed by taking into account the influence of corrosion degree. Comparison between the model and test results showed that proposed model properly describes the dynamic response of the corroded high strength rebars.

  16. Statistical evaluation of the mechanical properties of high-volume class F fly ash concretes

    Yoon, Seyoon

    2014-03-01

    High-Volume Fly Ash (HVFA) concretes are seen by many as a feasible solution for sustainable, low embodied carbon construction. At the moment, fly ash is classified as a waste by-product, primarily of thermal power stations. In this paper the authors experimentally and statistically investigated the effects of mix-design factors on the mechanical properties of high-volume class F fly ash concretes. A total of 240 and 32 samples were produced and tested in the laboratory to measure compressive strength and Young\\'s modulus respectively. Applicability of the CEB-FIP (Comite Euro-international du Béton - Fédération Internationale de la Précontrainte) and ACI (American Concrete Institute) Building Model Code (Thomas, 2010; ACI Committee 209, 1982) [1,2] to the experimentally-derived mechanical property data for HVFA concretes was established. Furthermore, using multiple linear regression analysis, Mean Squared Residuals (MSRs) were obtained to determine whether a weight- or volume-based mix proportion is better to predict the mechanical properties of HVFA concrete. The significance levels of the design factors, which indicate how significantly the factors affect the HVFA concrete\\'s mechanical properties, were determined using analysis of variance (ANOVA) tests. The results show that a weight-based mix proportion is a slightly better predictor of mechanical properties than volume-based one. The significance level of fly ash substitution rate was higher than that of w/b ratio initially but reduced over time. © 2014 Elsevier Ltd. All rights reserved.

  17. Welding of nickel free high nitrogen stainless steel: Microstructure and mechanical properties

    Raffi Mohammed

    2017-04-01

    Full Text Available High nitrogen stainless steel (HNS is a nickel free austenitic stainless steel that is used as a structural component in defence applications for manufacturing battle tanks as a replacement of the existing armour grade steel owing to its low cost, excellent mechanical properties and better corrosion resistance. Conventional fusion welding causes problems like nitrogen desorption, solidification cracking in weld zone, liquation cracking in heat affected zone, nitrogen induced porosity and poor mechanical properties. The above problems can be overcome by proper selection and procedure of joining process. In the present work, an attempt has been made to correlate the microstructural changes with mechanical properties of fusion and solid state welds of high nitrogen steel. Shielded metal arc welding (SMAW, gas tungsten arc welding (GTAW, electron beam welding (EBW and friction stir welding (FSW processes were used in the present work. Optical microscopy, scanning electron microscopy and electron backscatter diffraction were used to characterize microstructural changes. Hardness, tensile and bend tests were performed to evaluate the mechanical properties of welds. The results of the present investigation established that fully austenitic dendritic structure was found in welds of SMAW. Reverted austenite pools in the martensite matrix in weld zone and unmixed zones near the fusion boundary were observed in GTA welds. Discontinuous ferrite network in austenite matrix was observed in electron beam welds. Fine recrystallized austenite grain structure was observed in the nugget zone of friction stir welds. Improved mechanical properties are obtained in friction stir welds when compared to fusion welds. This is attributed to the refined microstructure consisting of equiaxed and homogenous austenite grains.

  18. High-Performance Pressure Sensor for Monitoring Mechanical Vibration and Air Pressure

    Yancheng Meng

    2018-05-01

    Full Text Available To realize the practical applications of flexible pressure sensors, the high performance (sensitivity and response time as well as more functionalities are highly desired. In this work, we fabricated a piezoresistive pressure sensor based on the micro-structured composites films of multi-walled carbon nanotubes (MWCNTs and poly (dimethylsiloxane (PDMS. In addition, we establish efficient strategies to improve key performance of our pressure sensor. Its sensitivity is improved up to 474.13 kPa−1 by minimizing pressure independent resistance of sensor, and response time is shorten as small as 2 μs by enhancing the elastic modulus of polymer elastomer. Benefiting from the high performance, the functionalities of sensors are successfully extended to the accurate detection of high frequency mechanical vibration (~300 Hz and large range of air pressure (6–101 kPa, both of which are not achieved before.

  19. Mechanical Properties and Fractographic Analysis of High Manganese Steels After Dynamic Deformation Tests

    Jabłońska M.B.

    2014-10-01

    Full Text Available Since few years many research centres conducting research on the development of high-manganese steels for manufacturing of parts for automotive and railway industry. Some of these steels belong to the group of AHS possessing together with high strength a great plastic elongation, and an ideal uniform work hardening behavior. The article presents the dynamic mechanical properties of two types of high manganese austenitic steel with using a flywheel machine at room temperature with strain rates between 5×102÷3.5×103s?–1. It was found that the both studied steels exhibit a high sensitivity Rm to the strain rate. With increasing the strain rate from 5×102 to 3.5×103s?–1 the hardening dominates the process. The fracture analysis indicate that after dynamic test both steel is characterized by ductile fracture surfaces which indicate good plasticity of investigated steels.

  20. Decarburization behavior and mechanical properties of Inconel 617 during high temperature oxidation in He environment

    Kim, Young Do; Kim, Dae Gun; Jo, Tae Sun; Kim, Hoon Sup; Lim, Jeong Hun

    2010-04-01

    Among Generation IV reactor concepts, high temperature gas-cooled reactors (HTGRs) are high-efficiency systems designed for the economical production of hydrogen and electricity. Inconel 617 is a solid-solution strengthening Ni-based superalloy that shows excellent strength, creep-rupture strength, and oxidation resistance at high temperatures. Thus, it is a desirable candidate for tube material of IHX and HGD in HTGRs. In spite of these excellent properties, aging degradation by long time exposure at high temperature induced to deterioration of mechanical properties and furthermore alloys' lifetime because of Cr-depleted zone and carbide free zone below external scale. Also, machinability of Inconel 617 is a important property for system design. In this study, oxidation and decarbrization behavior were evaluated at various aging temperature and environment. Also, cold rolling was carried out for the machinability evaluation of Inconel 617 and then microstructure change was evaluated

  1. Effects of high fluoride intake on child mental work capacity: preliminary investigation into the mechanisms involved

    Li, Y.; Li, X.J.; Wei, S.Q. [Child & Adolescent Hygiene Teaching Research Station, Chengdu (China)

    2008-10-15

    A study was carried out on 157 children, age 12-13, from a coal-burning fluorosis endemic area together with an experiment looking into the effect of high fluoride intake in animals. The results showed that early, prolonged high fluoride intake causes a decrease in a child's mental work capacity and that prolonged high uptake of fluoride causes a child's levels of hair zinc to drop. A multifactoral correlative analysis demonstrated a direct correlation between hair zinc and mental work capacity. The decrease of 5-hydroxyindoleacetic acid and the increase of norepinephrine in animal brains exposed to high levels of fluoride suggest a possible mechanism for mental work capacity deficits in children. However, further research is necessary.

  2. Mechanical Properties and Fabrication of Nanostructured Mg_2SiO_4-MgAl_2O_4 Composites by High-Frequency Induction Heated Combustion

    Shon, In-Jin; Kang, Hyun-Su; Hong, Kyung-Tae; Doh, Jung-Mann; Yoon, Jin-Kook

    2011-01-01

    Nanopowders of MgO, Al_2O_3 and SiO_2 were made by high energy ball milling. The rapid sintering of nanostructured MgAl_2O_4-Mg_2SiO_4 composites was investigated by a high-frequency induction heating sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid for the application of nanomaterials. Highly dense nanostructured MgAl_2O_4-Mg_2SiO_4 composites were produced with simultaneous application of 80 MPa pressure and induced output current of total power capacity (15 kW) within 2 min. The sintering behavior, gain size and mechanical properties of MgAl_2O_4-Mg_2SiO_4 composites were investigated.

  3. Subsurface damage mechanism of high speed grinding process in single crystal silicon revealed by atomistic simulations

    Li, Jia; Fang, Qihong; Zhang, Liangchi; Liu, Youwen

    2015-01-01

    Highlights: • Molecular dynamic model of nanoscale high speed grinding of silicon workpiece has been established. • The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation during high speed grinding process are thoroughly investigated. • Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle. • The hydrostatic stress and von Mises stress by the established analytical model are studied subsurface damage mechanism during nanoscale grinding. - Abstract: Three-dimensional molecular dynamics (MD) simulations are performed to investigate the nanoscale grinding process of single crystal silicon using diamond tool. The effect of grinding speed on subsurface damage and grinding surface integrity by analyzing the chip, dislocation movement, and phase transformation are studied. We also establish an analytical model to calculate several important stress fields including hydrostatic stress and von Mises stress for studying subsurface damage mechanism, and obtain the dislocation density on the grinding subsurface. The results show that a higher grinding velocity in machining brittle material silicon causes a larger chip and a higher temperature, and reduces subsurface damage. However, when grinding velocity is above 180 m s −1 , subsurface damage thickness slightly increases because a higher grinding speed leads to the increase in grinding force and temperature, which accelerate dislocation nucleation and motion. Subsurface damage is studied by the evolution of surface area at first time for more obvious observation on transition from ductile to brittle, that provides valuable reference for machining nanometer devices. The von Mises stress and the hydrostatic stress play an important role in the grinding process, and explain the subsurface damage though dislocation mechanism under high

  4. COMPETITIVE ADVANTAGE IN THE ENTERPRISE PERFORMANCE

    PRUNEA Ana Daniela

    2014-07-01

    Full Text Available Rapid changes in market characteristics and the technological innovations are common and faster challenges, resulting in products, processes and technologies. The competitive advantage is volatile, difficult to obtain and more difficult to maintain and strengthened with consumers who through their individual choices polarization confirms the recognition performance and award competitive advantages, thus causing the competitive ranking of companies present in a particular market. The competitive advantage lies in the focus of the performance of companies in competitive markets and innovation is a source for obtaining and consolidating it. Companies will need to demonstrate the capacity to adapt to changes in the business environment so as to maintain the helded positions. This paper treats this aspect behavior that companies should adopt to get on the account of innovation a sustainable competitive advantage. I started of the work in the elaboration from the theory of developed by Michael Porter in his book "Competitive Advantage: Creating and Sustaining Superior Performance" we applied methods listed thus trying to point out possible ways of creating competitive advantage by companies. We have presented the sources of competitive advantage and the factors on which depends its creation. Walking theoretical research revealed how lack of competitive advantage leads to a lack of competitiveness of companies and the benefits that arise with the creation of this type of asset. Among the most important benefits is to increase performances. Once the competitive advantage is achieved, it must be maintained and updated market conditions and the methods that can be created a sustainable competitive advantage represent the answers to many of the companies questions are fighting for survival in an environment of fierce competition. The implementation of methods for obtaining competitive advantages, but also exist dangers, that every company should know them

  5. Thermodynamic advantages of nuclear desalination through reverse osmosis

    Bhattacharyya, K.P.; Prabhakar, S.; Tewari, P.K.

    2009-01-01

    Seawater Reverse Osmosis (SWRO) integrated with nuclear power station has significant thermodynamic advantages since it can utilize the waste heat available in the condenser cooling circuit and electrical power from the nuclear power plant with provision for using grid power in case of exigencies and shared infrastructure. Coupling of RO plants to the reactor is simple and straightforward and power loss due to RO unit, resulting in the loss of load, does not impact reactor turbine. Product water contamination probability is also very less since it has in-built mechanical barrier. Preheat reverse osmosis desalination has many thermodynamic advantages and studies have indicated improved performance characteristics thereby leading to savings in operational cost. The significant advantages include the operational flexibility of the desalination systems even while power plant is non-operational and non-requirement of safety systems for resource utilization. This paper brings out a comprehensive assessment of reverse osmosis process as a stand-alone nuclear desalination system. (author)

  6. Fatigue response of a PZT multilayer actuator under high-field electric cycling with mechanical preload

    Wang, Hong; Wereszczak, Andrew A.; Lin, Hua-Tay

    2009-01-01

    An electric fatigue test system was developed for evaluating the reliability of piezoelectric actuators with a mechanical loading capability. Fatigue responses of a lead zirconate titanate (PZT) multilayer actuator with a platethrough electrode configuration were studied under an electric field (1.7 times that of the coercive field of PZT material) and a concurrent mechanical preload (30.0 MPa). A total of 109 cycles was carried out. Variations in charge density and mechanical strain under the high electric field and constant mechanical loads were observed during the fatigue test. The dc and the first harmonic (at 10 Hz) dielectric and piezoelectric coefficients were subsequently characterized using fast Fourier transformation. Both the dielectric and the piezoelectric coefficients exhibited a monotonic decrease prior to 2.86×108 cycles under certain preloading conditions, and then fluctuated. Both the dielectric loss tangent and the piezoelectric loss tangent also fluctuated after a decrease. The results are interpreted and discussed with respect to domain wall activities, microdefects, and other anomalies.

  7. Molecular Mechanisms for High Hydrostatic Pressure-Induced Wing Mutagenesis in Drosophila melanogaster.

    Wang, Hua; Wang, Kai; Xiao, Guanjun; Ma, Junfeng; Wang, Bingying; Shen, Sile; Fu, Xueqi; Zou, Guangtian; Zou, Bo

    2015-10-08

    Although High hydrostatic pressure (HHP) as an important physical and chemical tool has been increasingly applied to research of organism, the response mechanisms of organism to HHP have not been elucidated clearly thus far. To identify mutagenic mechanisms of HHP on organisms, here, we treated Drosophila melanogaster (D. melanogaster) eggs with HHP. Approximately 75% of the surviving flies showed significant morphological abnormalities from the egg to the adult stages compared with control flies (p melanogaster induced by HHP were used to investigate the mutagenic mechanisms of HHP on organism. Thus 285 differentially expressed genes associated with wing mutations were identified using Affymetrix Drosophila Genome Array 2.0 and verified with RT-PCR. We also compared wing development-related central genes in the mutant flies with control flies using DNA sequencing to show two point mutations in the vestigial (vg) gene. This study revealed the mutagenic mechanisms of HHP-induced mutagenesis in D. melanogaster and provided a new model for the study of evolution on organisms.

  8. High temperature deformation mechanisms of L12-containing Co-based superalloys

    Titus, Michael Shaw

    Ni-based superalloys have been used as the structural material of choice for high temperature applications in gas turbine engines since the 1940s, but their operating temperature is becoming limited by their melting temperature (Tm =1300degrees C). Despite decades of research, no viable alternatives to Ni-based superalloys have been discovered and developed. However, in 2006, a ternary gamma' phase was discovered in the Co-Al-W system that enabled a new class of Co-based superalloys to be developed. These new Co-based superalloys possess a gamma-gamma' microstructure that is nearly identical to Ni-based superalloys, which enables these superalloys to achieve extraordinary high temperature mechanical properties. Furthermore, Co-based alloys possess the added benefit of exhibiting a melting temperature of at least 100degrees C higher than commercial Ni-based superalloys. Superalloys used as the structural materials in high pressure turbine blades must withstand large thermomechanical stresses imparted from the rotating disk and hot, corrosive gases present. These stresses induce time-dependent plastic deformation, which is commonly known as creep, and new superalloys must possess adequate creep resistance over a broad range of temperature in order to be used as the structural materials for high pressure turbine blades. For these reasons, this research focuses on quantifying high temperature creep properties of new gamma'-containing Co-based superalloys and identifying the high temperature creep deformation mechanisms. The high temperature creep properties of new Co- and CoNi-based alloys were found to be comparable to Ni-based superalloys with respect to minimum creep rates and creep-rupture lives at 900degrees C up to the solvus temperature of the gamma' phase. Co-based alloys exhibited a propensity for extended superlattice stacking fault formation in the gamma' precipitates resulting from dislocation shearing events. When Ni was added to the Co-based compositions

  9. On-Surface Pseudo-High-Dilution Synthesis of Macrocycles: Principle and Mechanism.

    Fan, Qitang; Wang, Tao; Dai, Jingya; Kuttner, Julian; Hilt, Gerhard; Gottfried, J Michael; Zhu, Junfa

    2017-05-23

    Macrocycles have attracted much attention due to their specific "endless" topology, which results in extraordinary properties compared to related linear (open-chain) molecules. However, challenges still remain in their controlled synthesis with well-defined constitution and geometry. Here, we report the successful application of the (pseudo-)high-dilution method to the conditions of on-surface synthesis in ultrahigh vacuum. This approach leads to high yields (up to 84%) of cyclic hyperbenzene ([18]-honeycombene) via an Ullmann-type reaction from 4,4″-dibromo-meta-terphenyl (DMTP) as precursor on a Ag(111) surface. The mechanism of macrocycle formation was explored in detail using scanning tunneling microscopy and X-ray photoemission spectroscopy. We propose that the dominant pathway for hyperbenzene (MTP) 6 formation is the stepwise desilverization of an organometallic (MTP-Ag) 6 macrocycle, which forms via cyclization of (MTP-Ag) 6 chains under pseudo-high-dilution conditions. The high probability of cyclization on the stage of the organometallic phase results from the reversibility of the C-Ag bond. The case is different from that in solution, in which cyclization typically occurs on the stage of a covalently bonded open-chain precursor. This difference in the cyclization mechanism on a surface compared to that in solution stems mainly from the 2D confinement exerted by the surface template, which hinders the flipping of chain segments necessary for cyclization.

  10. Microstructural control and high temperature mechanical property of ferritic/martensitic steels for nuclear reactor application

    Adetunji, G.J.

    1991-04-01

    The materials under study are 9-12% Cr ferritic/martensitic steels, alternative candidate materials for application in core components of nuclear power reactors. This work involves (1) Investigation of high temperature fracture mechanism during slow tensile and limited creep testing at 600 o C (2) Extensive study of solute element segregation both theoretically and experimentally (3) Investigation of effects by thermal ageing and irradiation on microstructural developments in relation to high temperature mechanical behaviour. From (1) the results obtained indicate that the important microstructural characteristics controlling the fracture of 9-12% Cr ferritic/martensitic steels at high temperature are (a) solute segregation to inclusion-matrix interfaces (b) hardness of the martensitic matrix and (c) carbide particle size distribution. From (2) the results indicate a strong concentration gradient of silicon and molybdenum near lath packet boundaries for certain quenching rates from the austenitizing temperature. From (3) high temperature tensile data were obtained for irradiated samples with thermally aged ones as control. (author)

  11. Growth Mechanism and Origin of High s p3 Content in Tetrahedral Amorphous Carbon

    Caro, Miguel A.; Deringer, Volker L.; Koskinen, Jari; Laurila, Tomi; Csányi, Gábor

    2018-04-01

    We study the deposition of tetrahedral amorphous carbon (ta-C) films from molecular dynamics simulations based on a machine-learned interatomic potential trained from density-functional theory data. For the first time, the high s p3 fractions in excess of 85% observed experimentally are reproduced by means of computational simulation, and the deposition energy dependence of the film's characteristics is also accurately described. High confidence in the potential and direct access to the atomic interactions allow us to infer the microscopic growth mechanism in this material. While the widespread view is that ta-C grows by "subplantation," we show that the so-called "peening" model is actually the dominant mechanism responsible for the high s p3 content. We show that pressure waves lead to bond rearrangement away from the impact site of the incident ion, and high s p3 fractions arise from a delicate balance of transitions between three- and fourfold coordinated carbon atoms. These results open the door for a microscopic understanding of carbon nanostructure formation with an unprecedented level of predictive power.

  12. Metal resistance or tolerance? Acidophiles confront high metal loads via both abiotic and biotic mechanisms

    Mark eDopson

    2014-04-01

    Full Text Available All metals are toxic at high concentrations and consequently their intracellular concentrations must be regulated. Acidophilic microorganisms have an optimum growth pH < 3 and proliferate in natural and anthropogenic low pH environments. Some acidophiles are involved in the catalysis of sulfide mineral dissolution, resulting in high concentrations of metals in solution. Acidophiles are often described as highly metal resistant via mechanisms such as multiple and/or more efficient active resistance systems than are present in neutrophiles. However, this is not the case for all acidophiles and we contend that their growth in high metal concentrations is partially due to an intrinsic tolerance as a consequence of the environment in which they live. In this perspective, we highlight metal tolerance via complexation of free metals by sulfate ions and passive tolerance to metal influx via an internal positive cytoplasmic transmembrane potential. These tolerance mechanisms have been largely ignored in past studies of acidophile growth in the presence of metals and should be taken into account.

  13. Multifunctional hybrid diode: Study of photoresponse, high responsivity, and charge injection mechanisms

    Singh, Jitendra; Singh, R. G.; Gautam, Subodh K.; Singh, Fouran

    2018-05-01

    A multifunctional hybrid heterojunction diode is developed on porous silicon and its current density-voltage characteristics reveal a good rectification ratio along with other superior parameters such as ideality factor, barrier height and series resistance. The diode also functions as an efficient photodiode to manifest high photosensitivity with high responsivity under illumination with broadband solar light, UV light, and green light. The diode is also carefully scrutinized for its sensitivity and repeatability over many cycles under UV and green light and is found to have a quick response and extremely fast recovery times. The notable responsivity is attributed to the generation of high density of excitons in the depletion region by the absorption of incident photons and their separation by an internal electric field besides an additional photocurrent due to the charging of polymer chains. The mechanisms of generation, injection and transport of charge carriers are explained by developing a schematic energy band diagram. The transport phenomenon of carriers is further investigated from room temperature down to a very low temperature of 10 K. An Arrhenius plot is made to determine the Richardson constant. Various diode parameters as mentioned above are also determined and the dominance of the transport mechanism of charge carriers in different temperature regimes such as diffusion across the junction and/or quantum tunneling through the barriers are explained. The developed multifunction heterojunction hybrid diodes have implications for highly sensitive photodiodes in the UV and visible range of electromagnetic spectrum that can be very promising for efficient optoelectronic devices.

  14. Departure mechanisms for host search on high-density patches by the Meteorus pulchricornis.

    Sheng, Sheng; Feng, Sufang; Meng, Ling; Li, Baoping

    2014-01-01

    Less attention has been paid to the parasitoid-host system in which the host occurs in considerably high density with a hierarchical patch structure in studies on time allocation strategies of parasitoids. This study used the parasitoid Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae) and the Oriental leafworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) as the parasitoids-host model system to investigate patch-leaving mechanisms as affected by the high-host density, hierarchical patch structure, and foraging behaviors on both former and current patches. The results showed that three out of eight covariates tested had significant effects on the patch-leaving tendency, including the host density, ovipositor insertion, and host rejection on the current patch. The parasitoid paid more visits to the patch with high-density hosts. While the patch with higher host densities decreased the leaving tendency, the spatial distribution of hosts examined had no effect on the leaving tendency. Both oviposition and host rejection decreased the patch-leaving tendency. The variables associated with the former patch, such as the host density and number of ovipositor insertions, however, did not have an effect on the leaving tendency. Our study suggested that M. pulchricornis females may use an incremental mechanism to exploit high-density patches to the fullest. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

  15. High-Performance Buildings – Value, Messaging, Financial and Policy Mechanisms

    McCabe, Molly

    2011-02-22

    At the request of the Pacific Northwest National Laboratory, an in-depth analysis of the rapidly evolving state of real estate investments, high-performance building technology, and interest in efficiency was conducted by HaydenTanner, LLC, for the U.S. Department of Energy (DOE) Building Technologies Program. The analysis objectives were • to evaluate the link between high-performance buildings and their market value • to identify core messaging to motivate owners, investors, financiers, and others in the real estate sector to appropriately value and deploy high-performance strategies and technologies across new and existing buildings • to summarize financial mechanisms that facilitate increased investment in these buildings. To meet these objectives, work consisted of a literature review of relevant writings, examination of existing and emergent financial and policy mechanisms, interviews with industry stakeholders, and an evaluation of the value implications through financial modeling. This report documents the analysis methodology and findings, conclusion and recommendations. Its intent is to support and inform the DOE Building Technologies Program on policy and program planning for the financing of high-performance new buildings and building retrofit projects.

  16. Influence of High Temperature Treatment on Mechanical Behavior of a Coarse-grained Marble

    Rong, G.; Peng, J.; Jiang, M.

    2017-12-01

    High temperature has a significant influence on the physical and mechanical behavior of rocks. With increasing geotechnical engineering structures concerning with high temperature problems such as boreholes for oil or gas production, underground caverns for storage of radioactive waste, and deep wells for injection of carbon dioxides, etc., it is important to study the influence of temperature on the physical and mechanical properties of rocks. This paper experimentally investigates the triaxial compressive properties of a coarse-grained marble after exposure to different high temperatures. The rock specimens were first heated to a predetermined temperature (200, 400, and 600 oC) and then cooled down to room temperature. Triaxial compression tests on these heat-treated specimens subjected to different confining pressures (i.e., 0, 5, 10, 15, 20, 25, 30, 35, and 40 MPa) were then conducted. Triaxial compression tests on rock specimens with no heat treatment were also conducted for comparison. The results show that the high temperature treatment has a significant influence on the microstructure, porosity, P-wave velocity, stress-strain relation, strength and deformation parameters, and failure mode of the tested rock. As the treatment temperature gradually increases, the porosity slightly increases and the P-wave velocity dramatically decreases. Microscopic observation on thin sections reveals that many micro-cracks will be generated inside the rock specimen after high temperature treatment. The rock strength and Young's modulus show a decreasing trend with increase of the treatment temperature. The ductility of the rock is generally enhanced as the treatment temperature increases. In general, the high temperature treatment weakens the performance of the tested rock. Finally, a degradation parameter is defined and a strength degradation model is proposed to characterize the strength behavior of heat-treated rocks. The results in this study provide useful data for

  17. Microstructure evaluation and mechanical behavior of high-niobium containing titanium aluminides

    Bean, Glenn Estep, Jr.

    Ti-Al-Nb-based alloys with gamma(TiAl)+sigma(Nb2Al) microstructure have shown promise for potential high temperature applications due to their high specific strength. Recent research has been aimed towards increasing strength and operating temperatures through microstructural refinement and control. Alloys with 10 - 30% sigma-phase have been investigated, exploring relationships between chemistry, microstructure development, and flow behavior. Alloys with composition Ti-45Al-xNb-5Cr-1Mo (where x = 15, 20, 25 at%) have been produced, characterized, and tested at high temperature under compression. Processing, microstructure and mechanical property relationships are thoroughly investigated to reveal a significant connection between phase stability, morphology and their resultant effects on mechanical properties. Phase transformation temperatures and stability ranges were predicted using the ThermoCalc software program and a titanium aluminide database, investigated through thermal analysis, and alloys were heat treated to develop an ultrafine gamma+sigma microstructure. It has been demonstrated that microstructural development in these alloys is sensitive to composition and processing parameters, and heating and cooling rates are vital to the modification of gamma+sigma microstructure in these alloys. Towards the goal of designing a high-Nb titanium aluminide with ultrafine, disconnected gamma+sigma morphology, it has been established that microstructural control can be accomplished in alloys containing 15-25at% Nb through targeted chemistry and processing controls. The strength and flow softening characteristics show strain rate sensitivity that is also affected by temperature. From the standpoint of microstructure development and mechanical behavior at elevated temperature, the most favorable results are obtained with the 20 at% Nb alloy, which produces a combination of high strength and fine disconnected gamma+sigma microstructure. Microstructural analysis reveals

  18. Studies on microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc welds

    Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    The present work is aimed at studying the microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc (SMA) welds made with Cromang-N electrode. Basis for selecting this electrode is to increase the solubility of nitrogen in weld metal due to high chromium and manganese content. Microstructures of the welds were characterized using optical microscopy (OM), field emission scanning electron microscopy (FESEM) and electron back scattered diffraction (EBSD) mainly to determine the morphology, phase analysis, grain size and orientation image mapping. Hardness, tensile and ductility bend tests were carried out to determine mechanical properties. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance using a GillAC basic electrochemical system. Constant load type testing was carried out to study stress corrosion cracking (SCC) behaviour of welds. The investigation results shown that the selected Cr–Mn–N type electrode resulted in favourable microstructure and completely solidified as single phase coarse austenite. Mechanical properties of SMA welds are found to be inferior when compared to that of base metal and is due to coarse and dendritic structure.

  19. Consideration on excitation mechanisms in a high-power two-jet plasma

    Zaksas, Natalia P.; Gerasimov, Vladimir A.

    2013-01-01

    The study of excitation mechanisms in the region before the jet confluence of a high-power two-jet plasma used for analysis of different powders has been undertaken. Distribution of excited levels of Fe atoms and ions according to the Boltzmann population was found. Measuring Fe atomic and ionic excitation temperatures showed their considerable difference (≈ 2000–2500 K). The effect of argon on line intensities of a wide range of elements was investigated by the experiment with argon covering. A negligible effect of argon covering on line intensities of atoms with ionization energy of 8 eV was revealed. This is likely to be due to Penning ionization by metastable argon followed by ion recombination with an electron and stepwise de-excitations. A more pronounced effect of argon covering was observed for ionic lines of investigated elements with total excitation energy ranging from 11 to 21 eV. Penning ionization followed by electron impact is believed to be a probable mechanism for ion excitation. The contribution of metastable argon to excitation processes results in departure from local thermodynamic equilibrium and different atomic and ionic excitation temperatures. - Highlights: • Excitation mechanisms were investigated in a high-power TJP. • Boltzmann population of excited levels of Fe atoms and ions takes place. • The considerable difference in Fe atomic and ionic excitation temperatures occurs. • Argon covering was used to study the argon effect on line intensities. • Participation of metastable argon in atom ionization was shown

  20. Sodium effects on mechanical performance and consideration in high temperature structural design for advanced reactors

    Natesan, K.; Li, Meimei; Chopra, O. K.; Majumdar, S.

    2009-07-01

    Sodium environmental effects are key limiting factors in the high temperature structural design of advanced sodium-cooled reactors. A guideline is needed to incorporate environmental effects in the ASME design rules to improve the performance reliability over long operating times. This paper summarizes the influence of sodium exposure on mechanical performance of selected austenitic stainless and ferritic/martensitic steels. Focus is on Type 316SS and mod.9Cr-1Mo. The sodium effects were evaluated by comparing the mechanical properties data in air and sodium. Carburization and decarburization were found to be the key factors that determine the tensile and creep properties of the steels. A beneficial effect of sodium exposure on fatigue life was observed under fully reversed cyclic loading in both austenitic stainless steels and ferritic/martensitic steels. However, when hold time was applied during cyclic loading, the fatigue life was significantly reduced. Based on the mechanical performance of the steels in sodium, consideration of sodium effects in high temperature structural design of advanced fast reactors is discussed.

  1. New insights into mechanisms of sonothrombolysis using ultra-high-speed imaging.

    Chen, Xucai; Leeman, Jonathan E; Wang, Jianjun; Pacella, John J; Villanueva, Flordeliza S

    2014-01-01

    Thrombotic arterial occlusion is the principal etiology for acute cardiovascular syndromes such as stroke, myocardial infarction and unstable angina. Exposing the thrombus to ultrasound and microbubbles facilitates thrombus disruption, making "sonothrombolysis" a potentially powerful therapeutic strategy for thromboembolic diseases. However, optimization of such a strategy, and hence clinical translation, is constrained by an incomplete understanding of mechanisms by which ultrasound-induced microbubble vibrations disrupt blood clots. We posit that previously reported sonothrombolytic efficacy using inertial cavitation regimes was due, at least in part, to mechanical clot disruption by oscillating microbubbles. To test this hypothesis, we optically characterized lipid microbubble interactions with thrombus in the presence of ultrasound using a recently developed ultra-high-speed microscopy imaging system to visualize microbubble acoustic behaviors at megahertz frame rates. A microscope/acoustic stage designed for the system allowed an experimentally created thrombus and microbubbles to be insonified at a co-localized acoustic and optical focus during synchronized high-speed imaging. Under inertial cavitation conditions, large-amplitude microbubble oscillations caused thrombus deformation and pitting. Acoustic radiation forces (Bjerknes forces) further augmented microbubble-thrombus interaction. These observations suggest that a direct mechanical effect of oscillating lipid microbubbles on an adjacent thrombus may play a role in mediating clot disruption in the presence of specific ultrasound conditions. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  2. Advantages and limitations of peer assessment

    Karmen Goršak, Karmen Pižorn

    2010-12-01

    Full Text Available This article examines current theoretical work and research findings regarding the effectiveness of peer assessment. The main purpose of the article is to define peer asses sment and its subcategory peer feedback and to present the advantages and limitations of peer assessment derived from different research findings. In addition, conditions and strategies to successfully guarantee the benefits of peer assessment are presented. The main research studies, mentioned in this article, have been carried out in different disciplines in higher education programmes and their findings reveal positive students’ and teachers’ attitude to peer assessment as well as high correlation between peers’ and te achers’ grades. The main results of the studies show a positive effect of peer assessment on student’s active role in the process of learning and assessment, the development of social and professional skills, student’s autonomy, critical thinking, peer and selfassessment skills. Recommendations for implementing peer assessment within foreign language tea ching, as well as implications for future research work are provided.

  3. The greenhouse advantage of natural gas appliances

    Coombe, N.

    2000-01-01

    The life cycle report prepared recently by Energetics for the AGA, Assessment of Greenhouse Gas Emissions from Natural Gas, demonstrates clearly the greenhouse advantage natural gas has over coal in generating electricity. This study also goes one step further in applying this life cycle approach to the use of space and water heating within the home. The study shows the significant green-house advantage that natural gas appliances have over electric appliances. Findings from other studies also support this claim. The natural gas suppliers are encouraged to take advantage of the marketing opportunity that these studies provide, offering the householders the fuel that will significantly reduce their contribution to greenhouse emission

  4. Electro-Thermo-Mechanical Analysis of High-Power Press-Pack Insulated Gate Bipolar Transistors under Various Mechanical Clamping Conditions

    Hasmasan, Adrian Augustin; Busca, Cristian; Teodorescu, Remus

    2014-01-01

    With the continuously increasing demand for energy and the limited supply of fossil fuels, renewable power sources are becoming ever more important. Knowing that future energy demand will grow, manufacturers are increasing the size of new wind turbines (WTs) in order to reduce the cost of energy...... production. The reliability of the components has a large impact on the overall cost of a WT, and press-pack (PP) insulated gate bipolar transistors (IGBTs) could be a good solution for future multi-megawatt WTs because of advantages like high power density and reliability. When used in power converters, PP...

  5. Effects of thermal - mechanical treatment in the creep - and tensile properties of niobium at high temperature

    Botta Filho, W.J.; Pinatti, Dyonisio G.

    1981-01-01

    Mechanical behavior of Nb at high temperature was studied based upon the samples morfology. The samples were obtainned after thermal mechanical treatment of 50mm diameter and 250mm length ingot produced by electron beam vacuum. A lot of the samples was tensile tested as a function of temperature showing small interstitials solute effect and a matrix hardened probably by substitutionals. Other lot was creep tested at homologous temperature of 0,34 and stress between 80 and 120 MPa. The results of these tests were analysed as a function of the sample morfology and showed a dependence of the percentage of recrystalization and of the grain size on the minimum creep rate. The fracture analysis showed significant effect of the oxygen content although it didn't contribute to the creep results. (Author) [pt

  6. Changes in mechanical properties due to gamma irradiation of high-density polyethylene (HDPE

    S. S. Cota

    2007-06-01

    Full Text Available This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates.

  7. Mechanically stable tuning fork sensor with high quality factor for the atomic force microscope.

    Kim, Kwangyoon; Park, Jun-Young; Kim, K B; Lee, Naesung; Seo, Yongho

    2014-01-01

    A quartz tuning fork was used instead of cantilever as a force sensor for the atomic force microscope. A tungsten tip was made by electrochemical etching from a wire of 50 µm diameter. In order to have mechanical stability of the tuning fork, it was attached on an alumina plate. The tungsten tip was attached on the inside end of a prong of a tuning fork. The phase shift was used as a feedback signal to control the distance between the tip and sample, and the amplitude was kept constant using a lock-in amplifier and a homemade automatic gain controller. Due to the mechanical stability, the sensor shows a high quality factor (∼10(3)), and the image quality obtained with this sensor was equivalent to that of the cantilever-based AFM. © 2014 Wiley Periodicals, Inc.

  8. Effect of surface decarburization on the mechanical properties of high strength low alloy steel

    Saqib, S.

    1993-01-01

    An attempt has been made to study the relationship of mechanical properties with the microstructure of a high strength low alloy steel. A thorough investigation was conducted on the steel sheet and variation in mechanical properties was observed across its thickness with a change in the microstructure. Change in hardness and tensile strength at the surface compare to the core of the material is attributed to decarburization. The current research indicates that the correlation between hardness and tensile strength is not valid for steels if the hardness is determined on the surface only. Great care should be taken at the time of determination of tensile strength by using conversion charts/tables on the basis of hardness values obtained by practical means. (author)

  9. Mechanisms of High Energy Hadron-Nucleus and Nucleus-Nucleus Collision Processes

    Strugalski, Z.

    1994-01-01

    Mechanisms of high energy hadron-nucleus and nucleus-nucleus collision processes are depicted qualitatively, as prompted experimentally. In hadron-nucleus collisions the interaction of the incident hadron in intranuclear matter is localized in small cylindrical volume, with the radius as large as the strong interaction range is, centered on the hadron course in the nucleus. The nucleon emission is induced by the hadron in its passing through the nucleus; particles are produced via intermediate objects produced in 2 → 2 endoergic reactions of the hadron and its successors with downstream nucleons. In nucleus-nucleus collisions, the outcome of the reaction appears as the composition of statistically independent hadron-nucleus collision outcomes at various impact parameters. Observable effects supporting such mechanisms are discussed. 51 refs

  10. Deformation mechanism in graphene nanoplatelet reinforced tantalum carbide using high load in situ indentation

    Zhang, Cheng; Boesl, Benjamin [Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Silvestroni, Laura; Sciti, Diletta [Institute of Science and Technology for Ceramics (ISTEC), CNR-ISTEC, Via Granarolo 64, 48018 Faenza (Italy); Agarwal, Arvind, E-mail: agarwala@fiu.edu [Plasma Forming Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States)

    2016-09-30

    High load in-situ indentation testing with real time SEM imaging was carried out on spark plasma sintered graphene nanoplatelets (GNP) reinforced TaC composites. The prime goal of this study was to understand the deformation behavior and the reinforcing mechanisms of GNPs. The results suggest that addition of GNPs had significant effect on dissipating indentation energy and confining the overall damage area to a localized region of TaC. The average crack length reduced by 26% whereas total damage area shrunk by 85% in TaC-5 vol% GNP sample as compared to pure TaC. TEM analysis concluded that well dispersed GNPs result in a strong and clean interface between TaC and GNP with trace amount of amorphous layer that leads to improved energy dissipation mechanism.

  11. Micromechanical Models of Mechanical Response of High Performance Fibre Reinforced Cement Composites

    Li, V. C.; Mihashi, H.; Alwan, J.

    1996-01-01

    generation of FRC with high performance and economical viability, is in sight. However, utilization of micromechanical models for a more comprehensive set of important HPFRCC properties awaits further investigations into fundamental mechanisms governing composite properties, as well as intergrative efforts......The state-of-the-art in micromechanical modeling of the mechanical response of HPFRCC is reviewed. Much advances in modeling has been made over the last decade to the point that certain properties of composites can be carefully designed using the models as analytic tools. As a result, a new...... across responses to different load types. Further, micromechanical models for HPFRCC behavior under complex loading histories, including those in fracture, fatigue and multuaxial loading are urgently needed in order to optimize HPFRCC microstrcuctures and enable predictions of such material in structures...

  12. Influence of Carbide Modifications on the Mechanical Properties of Ultra-High-Strength Stainless Steels

    Seo, Joo-Young; Park, Soo-Keun; Kwon, Hoon; Cho, Ki-Sub

    2017-10-01

    The mechanical properties of ultra-high-strength secondary hardened stainless steels with varying Co, V, and C contents have been studied. A reduced-Co alloy based on the chemical composition of Ferrium S53 was made by increasing the V and C content. This changed the M2C-strengthened microstructure to a MC plus M2C-strengthened microstructure, and no deteriorative effects were observed for peak-aged and over-aged samples despite the large reduction in Co content from 14 to 7 wt pct. The mechanical properties according to alloying modification were associated with carbide precipitation kinetics, which was clearly outlined by combining analytical tools including small-angle neutron scattering (SANS) as well as an analytical TEM with computational simulation.

  13. Tensile properties and fracture mechanism of IN-100 superalloy in high temperature range

    Milan T. Jovanović

    2017-06-01

    Full Text Available Tensile properties and fracture mechanism of a polycrystalline IN-100 superalloy have been investigated in the range from room temperature to 900°C. Optical microscopy (OM and transmission electron microscopy (TEM applying replica technique were used for microstructural investigation, whereas scanning electron microscopy (SEM was utilized for fracture study. High temperature tensile tests were carried out in vacuumed chamber. Results show that strength increases up to 700°C, and then sharply decreases with further increase in temperature. Elongation increases very slowly (6-7.5% till 500°C, then decreases to 4.5% at 900°C. Change in elongation may be ascribed to a change of fracture mechanism. Appearance of a great number of microvoids prevails up to 500°C resulting in a slow increase of elongation, whereas above this temperature elongation decrease is correlated with intergranular crystallographic fracture and fracture of carbides.

  14. Changes in mechanical properties due to gamma irradiation of high-density polyethylene (HDPE)

    Cota, S.S.; Vasconcelos, V.; Senne Junior, M.; Carvalho, L.L.; Rezende, D.B.; Correa, R.F.

    2007-01-01

    This paper presents an experimental analysis of the effect of dose and dose rate parameters during gamma irradiation of high-density polyethylene (HDPE) samples. Considerations concerning the influence of these parameters on HDPE mechanical strength properties as a result of the predominance of oxidative degradation or of cross-linking are presented. The experimental results show an improvement of HDPE mechanical strength as dose increases, indicating the predominance of cross-linking over oxidative degradation and that lower doses are necessary to obtain a similar change in resistance parameters when radiation is applied at lower dose rates, showing that gamma radiation affects the HDPE in a more efficient way at lower dose rates. (author)

  15. Grain boundary sliding mechanism during high temperature deformation of AZ31 Magnesium alloy

    Roodposhti, Peiman Shahbeigi, E-mail: pshahbe@ncsu.edu [North Carolina State University (United States); University of Connecticut (United States); Sarkar, Apu; Murty, Korukonda Linga [North Carolina State University (United States); Brody, Harold [University of Connecticut (United States); Scattergood, Ronald [North Carolina State University (United States)

    2016-07-04

    High temperature tensile creep tests were conducted on AZ31 Magnesium alloy at low stress range of 1–13 MPa to clarify the existence of grain boundary sliding (GBS) mechanism during creep deformation. Experimental data within the GBS regime shows the stress exponent is ~2 and the activation energy value is close to that for grain boundary diffusion. Analyses of the fracture surface of the sample revealed that the GBS provides many stress concentrated sites for diffusional cavities formation and leads to premature failure. Scanning electron microscopy images show the appearances of both ductile and brittle type fracture mechanism. X-ray diffraction line profile analysis (based on Williamson-Hall technique) shows a reduction in dislocation density due to dynamic recovery (DRV). A correlation between experimental data and Langdon's model for GBS was also demonstrated.

  16. Effect of thermal ageing on mechanical properties of a high-strength ODS alloy

    Hong, Sung Hoon; Kim, Sung Hwan; Jang, Chang Heui [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Tae Kyu [Nuclear Materials DivisionKorea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    A new high-strength ODS alloy, ARROS, was recently developed for the application as the cladding material of a Sodium-cooled fast reactor (SFR). To assess the long-term integrity under thermal ageing, ARROS was thermally aged in air at 650°C for 1000 h. The degree of thermal ageing was assessed by mechanical tests such as uniaxial tensile, hardness, and small punch tests at from room temperature to 650°C. Tensile strength was slightly decreased but elongation, hardness, and small punch energy were hardly changed at all test temperatures for the specimen aged at 650°C for 1000 h. However, the variation in mechanical properties such as hardness and small punch energy increased after thermal ageing. Using the test results, the correlation between tensile strength and maximum small punch load was established.

  17. Development of a high specific stiffness mechanically milled FeAl intermetallic alloy

    Baccino, R; San Filippo, D; Martel, P; Moret, F

    1996-12-31

    Powder metallurgy techniques such as gas atomization and mechanical milling have been used to develop a FeAl alloy with enhanced ductility and strength at both low and high temperature. The improvement method combines ductility increase by grain boundary strengthening, grain size reduction and oxide dispersion strengthening. The material has been characterized and tested in the form of extruded bars. Microstructure, order and texture of as-extruded and heat treated samples have been studied by TEM, X-ray diffraction and Moessbauer spectroscopy. Physical and mechanical properties of the material are compared to some conventional engineering alloys in order to discuss the conceivable applications in aeronautical and automotive industries. (authors). 22 refs., 4 figs., 2 tabs.

  18. Using integration technology as a strategic advantage.

    Fry, P A

    1993-08-01

    The underlying premise of the Managed Competition Act previously cited is that through managed competition providers will be forced to lower care costs while increasing the level of positive care outcomes. Because it may also be that tomorrow's hospitals will find a severe rationing of technology, what can they do to prepare? Most of the systems in place today already have built within them all the necessary potential to address this premise and technology requirement with no change, no conversion, no expense for new equipment and software, and no disruption in day-to-day operations, just a little re-engineering. Today, however, these systems are similar to a 20-mule team pulling in different directions: all the power is there, but the wagon remains motionless and totally unable to reach its objective. It takes a skilled wagonmaster to bring them together, to make the mules work as a cohesive unit, to make the power of 20 mules greater than the sum of 20 mules. So it is and will be for the hospital of tomorrow. System integration is no longer a question of whether but of when. Those hospitals that use it today as a strategic advantage will be in a better position tomorrow to use it as a competitive strategic advantage in an environment that will reward low cost and high positive care outcomes and will penalize those that cannot compete. The technology is already here and economically within reach of nearly every hospital, just waiting to be used. The question that must nag all of us who want to make the health care system of America better is, Why not make the when now? Rich Helppie, president of Superior Consultant Company, summarized the solution well: The old ways will not give way to the new overnight. The re-engineering process in healthcare must evolve. Compared to the last 20 years, however, such evolution may appear to be a massive, forthright, complete, comprehensive, drastic and rapid revolution. Survival is the name of the game, and for healthcare

  19. High-performance computing for structural mechanics and earthquake/tsunami engineering

    Hori, Muneo; Ohsaki, Makoto

    2016-01-01

    Huge earthquakes and tsunamis have caused serious damage to important structures such as civil infrastructure elements, buildings and power plants around the globe.  To quantitatively evaluate such damage processes and to design effective prevention and mitigation measures, the latest high-performance computational mechanics technologies, which include telascale to petascale computers, can offer powerful tools. The phenomena covered in this book include seismic wave propagation in the crust and soil, seismic response of infrastructure elements such as tunnels considering soil-structure interactions, seismic response of high-rise buildings, seismic response of nuclear power plants, tsunami run-up over coastal towns and tsunami inundation considering fluid-structure interactions. The book provides all necessary information for addressing these phenomena, ranging from the fundamentals of high-performance computing for finite element methods, key algorithms of accurate dynamic structural analysis, fluid flows ...

  20. Effect of high pressure hydrogen on the mechanical characteristics of single carbon fiber

    Jeon, Sang Koo; Kwon, Oh Heon; Jang, Hoon-Sik; Ryu, Kwon Sang; Nahm, Seung Hoon

    2018-02-01

    In this study, carbon fiber was exposed to a pressure of 7 MPa for 24 h in high pressure chamber. The tensile test for carbon fiber was conducted to estimate the effect on the high pressure hydrogen in the atmosphere. To determine the tensile strength and Weibull modulus, approximately thirty carbon fiber samples were measured in all cases, and carbon fiber exposed to high pressure argon was evaluated to verify only the effect of hydrogen. Additionally, carbon fiber samples were annealed at 1950 °C for 1 h for a comparison with normal carbon fiber and then tested under identical conditions. The results showed that the tensile strength scatter of normal carbon fiber exposed to hydrogen was relatively wider and the Weibull modulus was decreased. Moreover, the tensile strength of the annealed carbon fiber exposed to hydrogen was increased, and these samples indicated a complex Weibull modulus because the hydrogen stored in the carbon fiber influenced the mechanical characteristic.

  1. Mechanisms of joint and microstructure formation in high power ultrasonic spot welding 6111 aluminium automotive sheet

    Bakavos, D.; Prangnell, P.B.

    2010-01-01

    Resistance spot welding (RSW) is difficult to apply to aluminium automotive alloys. High power ultrasonic spot welding (HP-USW) is a new alternative method which is extremely efficient, using ∼2% of the energy of RSW. However, to date there have been few studies of the mechanisms of bond formation and the material interactions that take place with this process. Here, we report on a detailed investigation where we have used X-ray tomography, high resolution SEM, and EBSD, and dissimilar alloy welds, to track the interface position and characterise the stages of weld formation, and microstructure evolution, as a function of welding energy. Under optimum conditions high quality welds are produced, showing few defects. Welding proceeds by the development and spread of microwelds, until extensive plastic deformation occurs within the weld zone, where the temperature reaches ∼380 deg. C. The origin of the weld interface 'flow features' characteristic of HP-USW are discussed.

  2. Biophysics of cancer progression and high-throughput mechanical characterization of biomaterials

    Osborne, Lukas Dylan

    Cancer metastasis involves a series of events known as the metastatic cascade. In this complex progression, cancer cells detach from the primary tumor, invade the surrounding stromal space, transmigrate the vascular system, and establish secondary tumors at distal sites. Specific mechanical phenotypes are likely adopted to enable cells to successfully navigate the mechanical environments encountered during metastasis. To examine the role of cell mechanics in cancer progression, I employed force-consistent biophysical and biochemical assays to characterize the mechanistic links between stiffness, stiffness response and cell invasion during the epithelial to mesenchymal transition (EMT). EMT is an essential physiological process, whose abnormal reactivation has been implicated in the detachment of cancer cells from epithelial tissue and their subsequent invasion into stromal tissue. I demonstrate that epithelial-state cells respond to force by evoking a stiffening response, and that after EMT, mesenchymal-state cells have reduced stiffness but also lose the ability to increase their stiffness in response to force. Using loss and gain of function studies, two proteins are established as functional connections between attenuated stiffness and stiffness response and the increased invasion capacity acquired after EMT. To enable larger scale assays to more fully explore the connection between biomechanics and cancer, I discuss the development of an automated array high throughput (AHT) microscope. The AHT system is shown to implement passive microbead rheology to accurately characterize the mechanical properties of biomaterials. Compared to manually performed mechanical characterizations, the AHT system executes experiments in two orders of magnitude less time. Finally, I use the AHT microscope to study the effect of gain of function oncogenic molecules on cell stiffness. I find evidence that our assay can identify alterations in cell stiffness due to constitutive

  3. Characterisation of high-temperature damage mechanisms of oxide dispersion strengthened (ODS) ferritic steels

    Salmon-Legagneur, Hubert

    2017-01-01

    The development of the fourth generation of nuclear power plants relies on the improvement of cladding materials, in order to achieve resistance to high temperature, stress and irradiation dose levels. Strengthening of ferritic steels through nano-oxide dispersion allows obtaining good mechanical strength at high temperature and good resistance to irradiation induced swelling. Nonetheless, studies available from open literature evidenced an unusual creep behavior of these materials: high anisotropy in time to rupture and flow behavior, low ductility and quasi-inexistent tertiary creep stage. These phenomena, and their still unclear origin are addressed in this study. Three 14Cr ODS steels rods have been studied. Their mechanical behavior is similar to those of other ODS steels from open literature. During creep tests, the specimens fractured by through crack nucleation and propagation from the lateral surfaces, followed by ductile tearing once the critical stress intensity factor was reached at the crack tip. Tensile and creep properties did not depend on the chemical environment of specimens. Crack propagation tests performed at 650 C showed a low value of the stress intensity factor necessary to start crack propagation. The cracks followed an intergranular path through the smaller-grained regions, which partly explains the anisotropy of high temperature strength. Notched specimens have been used to study the impact of the main loading parameters (deformation rate, temperature, stress triaxiality) on macroscopic crack initiation and stable propagation, from the central part of the specimens. These tests allowed revealing cavities created during high temperature loading, but unexposed to the external environment. These cavities showed a high chemical reactivity of the free surfaces in this material. The performed tests also evidenced different types of grain boundaries, which presented different damage development behaviors, probably due to differences in local

  4. Exploring the sequential lineup advantage using WITNESS.

    Goodsell, Charles A; Gronlund, Scott D; Carlson, Curt A

    2010-12-01

    Advocates claim that the sequential lineup is an improvement over simultaneous lineup procedures, but no formal (quantitatively specified) explanation exists for why it is better. The computational model WITNESS (Clark, Appl Cogn Psychol 17:629-654, 2003) was used to develop theoretical explanations for the sequential lineup advantage. In its current form, WITNESS produced a sequential advantage only by pairing conservative sequential choosing with liberal simultaneous choosing. However, this combination failed to approximate four extant experiments that exhibited large sequential advantages. Two of these experiments became the focus of our efforts because the data were uncontaminated by likely suspect position effects. Decision-based and memory-based modifications to WITNESS approximated the data and produced a sequential advantage. The next step is to evaluate the proposed explanations and modify public policy recommendations accordingly.

  5. Measuring Coding Intensity in Medicare Advantage - SUPP.

    U.S. Department of Health & Human Services — In 2004, Medicare implemented a risk-adjustment system that pays Medicare Advantage (MA) plans based on diagnoses reported for their enrollees, giving the plans an...

  6. AquAdvantage Salmon Genetically modified organism

    Núñez Saurí, Ester; Universitat Autònoma de Barcelona. Facultat de Veterinària

    2014-01-01

    Póster AquAdvantage Salmon is a genetically modified organism developed by AquBounty Technologies. The objective of this transgenic organism is to increase the growth rate to obtain the same of conventional salmon faster.

  7. Tanzania's Revealed Comparative Advantage and Structural ...

    example, the contribution from vegetable products fell by 7%, and that from textiles .... 43 -‐ Furskins and artificial fur, manufactures thereof ... example, while Tanzania has comparative advantage in raw hides and skins (see Figure 6), it.

  8. Rotating-Sleeve Triboelectric-Electromagnetic Hybrid Nanogenerator for High Efficiency of Harvesting Mechanical Energy.

    Cao, Ran; Zhou, Tao; Wang, Bin; Yin, Yingying; Yuan, Zuqing; Li, Congju; Wang, Zhong Lin

    2017-08-22

    Currently, a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) have been hybridized to effectively scavenge mechanical energy. However, one critical issue of the hybrid device is the limited output power due to the mismatched output impedance between the two generators. In this work, impedance matching between the TENG and EMG is achieved facilely through commercial transformers, and we put forward a highly integrated hybrid device. The rotating-sleeve triboelectric-electromagnetic hybrid nanogenerator (RSHG) is designed by simulating the structure of a common EMG, which ensures a high efficiency in transferring ambient mechanical energy into electric power. The RSHG presents an excellent performance with a short-circuit current of 1 mA and open-circuit voltage of 48 V at a rotation speed of 250 rpm. Systematic measurements demonstrate that the hybrid nanogenerator can deliver the largest output power of 13 mW at a loading resistance of 8 kΩ. Moreover, it is demonstrated that a wind-driven RSHG can light dozens of light-emitting diodes and power an electric watch. The distinctive structure and high output performance promise the practical application of this rotating-sleeve structured hybrid nanogenerator for large-scale energy conversion.

  9. Investigation of deterioration mechanism of electrical ceramic insulating materials under high temperature

    Mizutani, Yoshinobu; Ito, Tetsuo; Okamoto, Tatsuki; Kumazawa, Ryoji; Aizawa, Rie; Moriyama, Hideshige

    2000-01-01

    It is thought that ceramic insulator can be applied to electric power equipments that are under high temperature not to be able use organic materials. Our research has suggested components of mica-alumina combined insulation. As the results of and carried out temperature accelerating test, combined insulation life is expected long term over 40 years at over 500-Celsius degrees. However to construct high reliable insulating system, it is clarified deterioration mechanism on combined insulation and evaluates life of that. Therefore we carried out metal behavior test and voltage aging test using mica-sheet and alumina-cloth that are components of combined insulation under high temperature in nitrogen gas atmosphere. It is cleared two metal behavior mechanisms: One is that the opening of insulator are filled up with copper that is oxidized, the other is the metal diffuses in alumina-cloth through surface. And distance of metal behavior is able to be estimated at modulate temperature and in modulate time. It is also cleared that alumina-cloth is deteriorated by metal behavior into alumina-cloth. These results indicate that combined insulation is deteriorated from electrode side by metal behavior and is finally broken down through alumina-cloth. (author)

  10. Concept of modular flexure-based mechanisms for ultra-high precision robot design

    M. Richard

    2011-05-01

    Full Text Available This paper introduces a new concept of modular flexure-based mechanisms to design industrial ultra-high precision robots, which aims at significantly reducing both the complexity of their design and their development time. This modular concept can be considered as a robotic Lego, where a finite number of building bricks is used to quickly build a high-precision robot. The core of the concept is the transformation of a 3-D design problem into several 2-D ones, which are simpler and well-mastered. This paper will first briefly present the theoretical bases of this methodology and the requirements of both types of building bricks: the active and the passive bricks. The section dedicated to the design of the active bricks will detail the current research directions, mainly the maximisation of the strokes and the development of an actuation sub-brick. As for the passive bricks, some examples will be presented, and a discussion regarding the establishment of a mechanical solution catalogue will conclude the section. Last, this modular concept will be illustrated with a practical example, consisting in the design of a 5-degree of freedom ultra-high precision robot.

  11. The strengthening mechanism of a nickel-based alloy after laser shock processing at high temperatures

    Li, Yinghong; Zhou, Liucheng; He, Weifeng; He, Guangyu; Wang, Xuede; Nie, Xiangfan; Wang, Bo; Luo, Sihai; Li, Yuqin

    2013-01-01

    We investigated the strengthening mechanism of laser shock processing (LSP) at high temperatures in the K417 nickel-based alloy. Using a laser-induced shock wave, residual compressive stresses and nanocrystals with a length of 30–200 nm and a thickness of 1 μm are produced on the surface of the nickel-based alloy K417. When the K417 alloy is subjected to heat treatment at 900 °C after LSP, most of the residual compressive stress relaxes while the microhardness retains good thermal stability; the nanocrystalline surface has not obviously grown after the 900 °C per 10 h heat treatment, which shows a comparatively good thermal stability. There are several reasons for the good thermal stability of the nanocrystalline surface, such as the low value of cold hardening of LSP, extreme high-density defects and the grain boundary pinning of an impure element. The results of the vibration fatigue experiments show that the fatigue strength of K417 alloy is enhanced and improved from 110 to 285 MPa after LSP. After the 900 °C per 10 h heat treatment, the fatigue strength is 225 MPa; the heat treatment has not significantly reduced the reinforcement effect. The feature of the LSP strengthening mechanism of nickel-based alloy at a high temperature is the co-working effect of the nanocrystalline surface and the residual compressive stress after thermal relaxation. (paper)

  12. The Temporal Limits of Technological Advantage

    2017-06-01

    technologically advanced capabilities. “ Technology , in fact, is one of the keys to understanding relations between Hitler’s regime and the German business ...strategy sought to “leverage US advantages in technologies 2 like big data, stealth, advanced manufacturing (e.g. 3-D printing), robotics, and... history has had different parameters and different results, examining historical situations in which a technological advantage has been achieved

  13. MOLDOVA: MISSED ADVANTAGES OF EURASIAN INTEGRATION

    Ludmila Vasiljevna Fokina

    2015-01-01

    Full Text Available The article is devoted to potentially missed advantages of Eurasian integration (EAEU for Moldova. Special attention is given to the branches in which the country could get evident advantages including agriculture, power engineering, external trade ties with the EAEU countries. Possible positive effects of Eurasian integration in solution of the Transnistrian problem, in the sphere of labour migration and other fields are also shown.

  14. COMPETITIVE ADVANTAGE IN THE ENTERPRISE PERFORMANCE

    PRUNEA Ana Daniela

    2014-01-01

    Rapid changes in market characteristics and the technological innovations are common and faster challenges, resulting in products, processes and technologies. The competitive advantage is volatile, difficult to obtain and more difficult to maintain and strengthened with consumers who through their individual choices polarization confirms the recognition performance and award competitive advantages, thus causing the competitive ranking of companies present in a particular market. The competiti...

  15. ENTERPRISE IRELAND: Design for Competitive Advantage Conference

    Dee, Peter

    2003-01-01

    A stimulating conference bringing together world leading experts on design to address the importance of brand development strategies to achieve competitive advantage. Peter Dee - Strategic Design and Marketing Consultant, specialised in the creation of brand development strategies for Enterprise Ireland’s Design Unit. Peter was responsible for the design and development of the the brand identity for the Enterprise Ireland Design for Competitive Advantage Conference in Dublin.

  16. Advantages and risks in service standardization

    Veres Zoltán

    2004-01-01

    Full Text Available Comparing the advantages and risks in standardizing services, there can be no clear-cut answer concerning the strategy to be followed. Exploiting advantages in the long run is only worth it for a provider of a service that is able to build up a powerful brand image. However, the more successful a service concept, the stronger the temptation to imitation. The success of imitators will sooner or later bring about multibrand loyalty.

  17. Theoretical aspects of competitive advantage and competition

    Hudakova, Ivana

    2009-01-01

    The concept of competitive advantage is well-known for many of us and a number of literary resources focused on entrepreneurship and functioning of economies deal with it, either directly or indirectly. The understanding of the term competitive advantage though sometimes varies. One can only perceive it when looking at it as a whole, a live organism that is constantly developing in a complex dynamic entrepreneurial environment, the individual parts of which do not function when separated from...

  18. Mechanisms of astrocytic K(+) clearance and swelling under high extracellular K(+) concentrations.

    Murakami, Shingo; Kurachi, Yoshihisa

    2016-03-01

    In response to the elevation of extracellular K(+) concentration ([K(+)]out), astrocytes clear excessive K(+) to maintain conditions necessary for neural activity. K(+) clearance in astrocytes occurs via two processes: K(+) uptake and K(+) spatial buffering. High [K(+)]out also induces swelling in astrocytes, leading to edema and cell death in the brain. Despite the importance of astrocytic K(+) clearance and swelling, the underlying mechanisms remain unclear. Here, we report results from a simulation analysis of astrocytic K(+) clearance and swelling. Astrocyte models were constructed by incorporating various mechanisms such as intra/extracellular ion concentrations of Na(+), K(+), and Cl(-), cell volume, and models of Na,K-ATPase, Na-K-Cl cotransporter (NKCC), K-Cl cotransporter, inwardly-rectifying K(+) (KIR) channel, passive Cl(-) current, and aquaporin channel. The simulated response of astrocyte models under the uniform distribution of high [K(+)]out revealed significant contributions of NKCC and Na,K-ATPase to increases of intracellular K(+) and Cl(-) concentrations, and swelling. Moreover, we found that, under the non-uniform distribution of high [K(+)]out, KIR channels localized at synaptic clefts absorbed excess K(+) by depolarizing the equivalent potential of K(+) (E K) above membrane potential, while K(+) released through perivascular KIR channels was enhanced by hyperpolarizing E K and depolarizing membrane potential. Further analysis of simulated drug effects revealed that astrocyte swelling was modulated by blocking each of the ion channels and transporters. Our simulation analysis revealed controversial mechanisms of astrocytic K(+) clearance and swelling resulting from complex interactions among ion channels and transporters.

  19. Logistics potentials in business competitive advantage creation

    Rafał Matwiejczuk

    2013-12-01

    Full Text Available Background: Companies constantly search for ways to achieve and sustain long-term competitive advantage. Among the factors influencing the competitive advantage creation there are so called logistics potentials, which constitute a component part of a business strategic potentials. Logistics resources, logistics capabilities and logistics competences are the main components of the logistics potentials structure and hierarchy. Methods: In order to recognize the logistics potentials which determine the competitive advantage creation one may use the assumptions and elements of contemporary management concepts, including strategic management. In particular the article deals with Resource-Based View (RBV, Dynamic Capabilities Concept (DCC and - first of all - Competence-Based Management (CBM. Results and conclusions: Several significant research projects have presented a wide scope and a large number of possibilities of logistics potentials (and logistics competences in particular influence on business competitive advantage creation. The article briefly presents the research results conducted by: (1 Michigan State University (USA, (2 European Logistics Association (ELA in cooperation with A.T. Kearney, (3 Computer Sciences Corporation and (4 Capgemini. The research results have pointed out to differentiated but at the same distinctive symptoms of logistics competences influence on competitive advantage creation. The article also refers to the results of the research carried out by the Chair of Logistics & Marketing at Opole University (Poland in companies operating in Poland. The research has been mainly dealing with the significance of logistics competences in competitive advantage creation.

  20. Integration of optical fibers in radiative environments: Advantages and limitations

    Girard, S.; Ouerdane, Y.; Boukenter, A.; Marcandella, C.; Bisutti, J.; Baggio, J.; Meunier, J. P.

    2011-01-01

    We review the advantages and limitations for the integration of optical fibers in radiative environments. Optical fibers present numerous advantages for applications in harsh environments such as their electromagnetic immunity. This explains the increasing interest of the radiation effects community to evaluate their vulnerability for future facilities. However, it is also well-known that optical fibers suffer from a degradation of their macroscopic properties under irradiation. We illustrate the major mechanisms and parameters that govern the degradation mechanism, mainly the radiation-induced attenuation phenomena. We focus on the fiber transient radiation responses when exposed to the pulsed and mixed environment associated with the Megajoule class lasers devoted to the fusion by inertial confinement study. (authors)

  1. Metallurgical and Mechanical Characterization of High Temperature Titanium Alloys Joined by Friction Stir Welding

    Gangwar, Kapil Dev

    In the world of joining, riveting and additive manufacturing, weight reduction, and omission of defects (at both macro and micro level) remain of paramount. Therefore, in the wake of ubiquitous fusion welding (FW) and widely accepted approach of riveting using Inconel bolts to resist corrosion at higher temperature, friction stir welding (FSW) has emerged as a novice jewel in friction based additive manufacturing industry. With advancements in automation of welding process and tool material, FSW of materials with higher work hardening such as steel and titanium has also become probable. Process and property relations associated with FSW are inevitable in case of dissimilar titanium alloys, due to presence of heterogeneity (whether atrocious or advantageous) in and around the weld nugget. These process property relationships are needed to be studied and addressed properly in order to optimize the processing window for improved mechanical and metallurgical properties. In this study FSWed similar and dissimilar butt joints of α+β, and near α titanium, alloys have been produced for varying processing conditions in order to study the effect of rotation speed (rpm) and traverse speed (TS; mm-min-1). The aim of this study is to assess the effect of tool geometry, tool rpm, TS on microstructure and mechanical properties of most widely used α+β titanium alloy, Ti-6Al-4V (Ti-64), standard grain and fine grain in addition to α+β,Ti-5Al-4V (T-54M), standard grain, and near α, Ti-6Al-2Mo-4Zr-2Sn (Ti-6242), standard grain (SG) and fine grain (FG). During FSW, a unique α+β fine-grained microstructure has been formed depending on whether or not the peak temperature in the weld nugget (WN) reached above or below β transus temperature. The resulting microstructure consists of acicular α+β, emanating from the prior β grain boundary as the weld cools off. The changes in the microstructure are observed by optical microscopy (OM). Later, a detailed analysis of material

  2. Compensation mechanisms at high temperature in Y-doped BaTiO3

    Paredes-Olguín, M.; Lira-Hernández, I.A.; Gómez-Yáñez, C.; Espino-Cortés, F.P.

    2013-01-01

    Samples of BaTiO 3 with different concentrations of Y were synthesized from powders. The mixtures of powders were pressed and sintered at 1500 °C for 1 h. Two groups of samples were processed, one satisfying Ba/(Ti+Y) 3+ occupies the Ti 4+ lattice sites. The conductivity behavior as a function of Y concentration suggests that the compensation mechanisms are hole and oxygen vacancies. Due to the presence of charge carriers in the material, high values for the dielectric constant and dielectric loss were observed. Analysis of the microstructure showed that the average grain size decreases as the Y concentration is increased.

  3. Mechanical properties of Mo and TZM alloy neutron-irradiated at high temperatures

    Ueda, Kazukiyo; Satou, Manabu; Hasegawa, Akira; Abe, Katsunori

    1997-01-01

    This work reports the mechanical properties of irradiated molybdenum (Mo) and its alloy, TZM. Recrystallized and stress-relieved specimens were irradiated at five temperatures between 373 and 800degC in FFTF/MOTA to fluence levels of 6.8 to 34 dpa. Irradiation embrittlement and hardening were evaluated by three-point bend test and Vickers hardness test, respectively. Stress-relieved materials showed the enough ductility even after high fluence irradiation. The role of layered structure of stress-relieved specimen was discussed. (author)

  4. Microstructure and mechanical properties of metallic high-temperature materials. Research report

    Mughrabi, H.; Gottstein, G.; Mecking, H.; Riedel, H.; Toboloski, J.

    1999-01-01

    This volume contains 38 lectures of research studies performed in the course of the Priority Programme 'Microstructure and Mechanical Properties of Metallic High-Temperature Materials' supported by the Deutsche Forschungsgemeinschaft (DFG) over a period of six years from 1991 to 1997. The four materials selected were: 1. light metal PM-aluminium and titanium base alloys; 2. ferritic chromium and austenitic alloy 800 steels; 3. (monocrystalline) nickel-base superalloys; and 4. nickel- and iron-base oxide-dispersion-strengthened superalloys. All papers have been abstracted separately for the ENERGY database

  5. Preparation of highly absorbing polymeric hydrogels by radiation processing: mechanical and physical properties

    Dragusin, M.

    1994-01-01

    Some highly absorbing polymeric hydrogels such as acrylic polymers were produced by radiation processing with gamma sources Co-60 of 10,000 Ci, 3 kGy/h and an electron beam accelerator of 3 - 6 MeV, 0.3 - 3 kGy/s. For practical purposes, such as different applications in agriculture, etc, we studied the physical properties of residual monomers by refractometric and polarographic methods and the mechanical properties (gel strength) with devices made in our laboratory. (Author)

  6. Mechanisms Governing the Creep Behavior of High Temperature Alloys for Generation IV Nuclear Energy Systems

    Vasudevan, Vijay; Carroll, Laura; Sham, Sam

    2015-01-01

    This research project, which includes collaborators from INL and ORNL, focuses on the study of alloy 617 and alloy 800H that are candidates for applications as intermediate heat exchangers in GEN IV nuclear reactors, with an emphasis on the effects of grain size, grain boundaries and second phases on the creep properties; the mechanisms of dislocation creep, diffusional creep and cavitation; the onset of tertiary creep; and theoretical modeling for long-term predictions of materials behavior and for high temperature alloy design.

  7. Mechanisms Governing the Creep Behavior of High Temperature Alloys for Generation IV Nuclear Energy Systems

    Vasudevan, Vijay [Univ. of Cincinnati, OH (United States); Carroll, Laura [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sham, Sam [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-06

    This research project, which includes collaborators from INL and ORNL, focuses on the study of alloy 617 and alloy 800H that are candidates for applications as intermediate heat exchangers in GEN IV nuclear reactors, with an emphasis on the effects of grain size, grain boundaries and second phases on the creep properties; the mechanisms of dislocation creep, diffusional creep and cavitation; the onset of tertiary creep; and theoretical modeling for long-term predictions of materials behavior and for high temperature alloy design.

  8. The mechanism behind redox instability of anodes in high-temperature SOFCs

    Klemensø, Trine; Chung, Charissa; Larsen, Peter Halvor

    2005-01-01

    Bulk expansion of the anode upon oxidation is considered to be responsible for the lack of redox stability in high-temperature solid oxide fuel cells (SOFCs). The bulk expansion of nickel-yttria stabilized zirconia (YSZ) anode materials was measured by dilatometry as a function of sample geometry......, ceramic component, temperature, and temperature cycling. The strength of the ceramic network and the degree of Ni redistribution appeared to be key parameters of the redox behavior. A model of the redox mechanism in nickel-YSZ anodes was developed based on the dilatometry data and macro...

  9. Mechanical twinning and texture evolution in severely deformed Ti-6Al-4V at high temperatures

    Yapici, Guney Guven; Karaman, Ibrahim; Luo Zhiping

    2006-01-01

    We have investigated the deformation behavior and texture evolution of two-phase Ti-6Al-4V subjected to severe plastic deformation using equal channel angular extrusion (ECAE) at a high temperature (∼0.55T m ). Significant deformation twinning activity was observed after one and two ECAE passes in a 90 deg, die at 800 deg. C. Twinning activity at such a high temperature is a first-time observation in this material and is attributed to the high strain and stress levels imposed during ECAE. High stress levels and the stress state can affect the separation of twinning partials considerably. Resolved shear stress magnitudes on twin partials were found to be high during the ECAE process that helps the nucleation of mechanical twinning. The twinning mode was identified as the {101-bar 1} type using electron diffraction patterns which is one of the twinning modes observed in Ti at temperatures above 350 deg. C. Although only one twinning variant was mainly evident after one pass, multiple twin variants of the same mode were observed after the second pass with a significant increase in twin volume fraction. ECAE processing aligned the basal planes of the hexagonal close-packed α phase, initially having a random texture, with the ECAE shear plane. Texture evolution during ECAE was successfully predicted using a viscoplastic self-consistent crystal plasticity framework capturing the effect of the observed twinning mode on texture. Mechanical twins formed during ECAE and grain refinement led to a noteworthy improvement in flow stresses under tension and compression at room temperature. A strong directional anisotropy in yield strengths was also evident which cannot be explained only by crystallographic texture. It was speculated that the asymmetry of critical resolved shear stresses of deformation modes and the processing-induced deformation structure should play a role. With the supporting evidence from our previous works on the severe plastic deformation of other

  10. High volume fly ash RCC for dams - I : mixture optimization and mechanical properties

    Jacobsen, S. [PEAB Construction Co., Oslo (Norway); Lahus, O. [Norwegian Building Research Inst., Oslo (Norway)

    2001-07-01

    Roller compacted concretes (RCC) were developed for the Norwegian Skjerka hydropower project. RCCs were developed to have a high-volume fly ash content to address environmental issues, including the reduction of carbon dioxide emissions associated with dam construction. They also makes good use of waste product and conserve natural resources. This study examined a series of mixtures to determine the appropriateness of using RCC as a competing alternative to the traditional rock fill dam proposed for the Skjerka hydropower project. The main advantage of RCC is speed, allowing a relatively large dam to be constructed in just one summer season, saving financial costs and providing early return on the investment. In addition, fly ash can be used in the structure, using clean and renewable energy. Several procedures to proportion RCC mixtures were proposed, including the optimal paste volume method which is based on the assumption that an optimal RCC should have just enough paste to fill the space between particles when the granular skeleton has reached its maximum density under compaction. With this assumption, RCC tests began in 1998 in the laboratories of the Norwegian Building Research Institute. An ordinary portland cement was used and combined with ordinary low lime fly ash. Both coarse and fine aggregate were used. The tests determined the optimum paste-mortar ratio, the content of coarse aggregates and the production of specimens for test on hardened and fresh concrete. The study showed that the compressive strength of RCC increased with increasing cement/(cement + fly ash) ratio. The permeability coefficient decreased with increasing cement-content and increasing cement/(cement + fly ash) ratio due to the slow pozzolanic reaction of fly ash making a more open pore structure. It was concluded that an optimized mixture can result in a high performance RCC in terms of fresh and hardened concrete properties. 15 refs., 5 tabs., 11 figs.

  11. Stress Corrosion Cracking of alloy 600 in high temperature water: a study of mechanisms

    Boursier, J.M.; Bouvier, O. de; Gras, J.M.; Noel, D.; Vaillant, F.; Rios, R.

    1992-12-01

    Investigations of the stress corrosion cracking behaviour of Alloy 600 tubing in high temperature water were performed in order to get a precise knowledge of the different stages of the cracking and their dependence on various parameters. The compatibility of the results with the main mechanisms to be considered was examined. Results showed three stages in the cracking: a true incubation time, a slow-rate propagation period followed by a rapid-propagation stage. Tests separating stress and strain rate contributions show that the strain rate is the main parameter which controls the crack propagation. The hydrogen overpressure was found to increase the crack growth rate up to 1-4 bar, but a strong decrease is observed from 4 to 20 bar. Analysis of the hydrogen ingress in the metal showed that it is neither correlated to the hydrogen overpressure nor to the severity of cracking; so cracking resulting from an hydrogen-model is unlikely. No detrimental effect of oxygen (4 bar) was noticed both in the mill-annealed and the sensitized conditions. Finally, none of the classical mechanisms, neither hydrogen-assisted cracking nor slip-step dissolution, can correctly describe the observed behaviour. Some fractographic examinations, and an influence of primary water on the creep rate of Alloy 600, lead to consider that other recent mechanisms, involving an interaction between dissolution and plasticity, have to be considered

  12. Mechanically activated fly ash as a high performance binder for civil engineering

    Rieger, D; Kullová, L; Čekalová, M; Novotný, P; Pola, M

    2017-01-01

    This study is aimed for investigation of fly ash binder with suitable properties for civil engineering needs. The fly ash from Czech brown coal power plant Prunerov II was used and mechanically activated to achieve suitable particle size for alkaline activation of hardening process. This process is driven by dissolution of aluminosilicate content of fly ash and by subsequent development of inorganic polymeric network called geopolymer. Hardening kinetics at 25 and 30 °C were measured by strain controlled small amplitude oscillatory rheometry with strain of 0.01 % and microstructure of hardened binder was evaluated by scanning electron microscopy. Strength development of hardened binder was investigated according to compressional and flexural strength for a period of 180 days. Our investigation finds out, that mechanically activated fly ash can be comparable to metakaolin geopolymers, according to setting time and mechanical parameters even at room temperature curing. Moreover, on the bases of long time strength development, achieved compressional strength of 134.5 after 180 days is comparable to performance of high grade Portland cement concretes. (paper)

  13. High temperature fatigue behaviour of TZM molybdenum alloy under mechanical and thermomechanical cyclic loads

    Shi, H.J.; Niu, L.S.; Korn, C.; Pluvinage, G.

    2000-01-01

    High temperature isothermal mechanical fatigue and in-phase thermomechanical fatigue (TMF) tests in load control were carried out on a molybdenum-based alloy, one of the best known of the refractory alloys, TZM. The stress-strain response and the cyclic life of the material were measured during the tests. The fatigue lives obtained in the in-phase TMF tests are lower than those obtained in the isothermal mechanical tests at the same load amplitude. It appears that an additional damage is produced by the reaction of mechanical stress cycles and temperature cycles in TMF situation. Ratcheting phenomenon occurred during the tests with an increasing creep rate and it was dependent on temperature and load amplitude. A model of lifetime prediction, based on the Woehler-Miner law, was discussed. Damage coefficients that are functions of the maximum temperature and the variation of temperature are introduced in the model so as to evaluate TMF lives in load control. With this method the lifetime prediction gives results corresponding well to experimental data

  14. Optimization of Mechanical, Dynamical and Thermal Properties of a High Performance Tread Compound for Radial Tires

    Mir Hamid Reza Ghoreishy

    2013-06-01

    Full Text Available A high performance passenger tire tread compound was optimized for its mechanical, dynamical and thermal properties. A reference compound was based on a blend of SBR and BR, sulfur and other ingredients without accelerator, carbon black and aromatic oil. The effects of CBS/TMTD and TBBS/TMTD as accelerator systems were studied with different quantities and the best accelerator system was chosen. Then, the blends of N330 and N550 carbon blacks were added in different quantities and the properties of these samples were studied to determine the best carbon black blend. Finally, the effect of different quantities of aromatic oil was investigated and the optimized quantity of aromatic oil and the final properties of tire tread compound were defined. The mechanical and dynamical tests were carried out on appropriate samples to determine tensile strength, elongation-at-break, fatigue-to-failure, abrasion resistance, hardness, resilience, dynamical-mechanical properties and temperature rise due to the heat build-up. The results showed that the compound containing 0.8 phr CBS, 0.7 phr TMTD, 40 phr N330,20 phr N550 and 15 phr aromatic oils demonstrated the best properties.

  15. Mechanism of the formation of hollow spherical granules using a high shear granulator.

    Asada, Takumi; Nishikawa, Mitsunori; Ochiai, Yasushi; Noguchi, Shuji; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

    2018-05-30

    Recently, we have developed a novel granulation technology to manufacture hollow spherical granules (HSGs) for controlled-release formulations; however, the mechanism of the granulation is still unclear. The aim of this study is to determine the mechanism of the formation of the HSGs using a high shear granulator. Samples of granulated material were collected at various times during granulation and were investigated using scanning electron microscope and X-ray computed tomography. It was observed that the granulation proceeded by drug layering to the polymer, followed by formation of a hollow in the granule. In addition, it was also found that generation of a crack in the adhered drug layer and air flow into the granules might be involved in forming the hollow in the structure. Observation of the granulation of formulations with different types of drugs and polymers indicated that negative pressure in the granules occurred and the granules caved in when the hollow was formed. The hollow-forming speed and the shell density of the hollow granules depended on the particular drug and polymer. Taken together, the granulation mechanism of HSGs was determined and this information will be valuable for HSGs technology development. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance

    Birm-June Kim

    2013-09-01

    Full Text Available The effect of individual and combined talc and glass fibers (GFs on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

  17. High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance.

    Huang, Runzhou; Xu, Xinwu; Lee, Sunyoung; Zhang, Yang; Kim, Birm-June; Wu, Qinglin

    2013-09-17

    The effect of individual and combined talc and glass fibers (GFs) on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE) composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE) values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

  18. The development of bioresorbable composite polymeric implants with high mechanical strength

    Sharma, Upma; Concagh, Danny; Core, Lee; Kuang, Yina; You, Changcheng; Pham, Quynh; Zugates, Greg; Busold, Rany; Webber, Stephanie; Merlo, Jonathan; Langer, Robert; Whitesides, George M.; Palasis, Maria

    2018-01-01

    Implants for the treatment of tissue defects should mimic the mechanical properties of the native tissue of interest and should be resorbable as well as biocompatible. In this work, we developed a scaffold from variants of poly(glycolic) acid which were braided and coated with an elastomer of poly(glycolide-co-caprolactone) and crosslinked. The coating of the scaffold with the elastomer led to higher mechanical strength in terms of compression, expansion and elasticity compared to braids without the elastomer coating. These composite scaffolds were found to have expansion properties similar to metallic stents, utilizing materials which are typically much weaker than metal. We optimized the mechanical properties of the implant by tuning the elastomer branching structure, crosslink density, and molecular weight. The scaffolds were shown to be highly resorbable following implantation in a porcine femoral artery. Biocompatibility was studied in vivo in an ovine model by implanting the scaffolds into femoral arteries. The scaffolds were able to support an expanded open lumen over 12 months in vivo and also fully resorbed by 18 months in the ovine model.

  19. High Electrocatalytic Response of a Mechanically Enhanced NbC Nanocomposite Electrode Towards Hydrogen Evolution Reaction

    Coy, Emerson

    2017-08-22

    Resistant and efficient electrocatalysts for hydrogen evolution reaction (HER) are desired to replace scarce and commercially expensive platinum electrodes. Thin film electrodes of metal-carbides are a promising alternative due to their reduced price and similar catalytic properties. However, most of the studied structures to date neglect long lasting chemical and structural stability, focusing only on electrochemical efficiency. Herein we report on a new approach to easily deposit and control the micro/nanostructure of thin film electrodes based on niobium carbide (NbC) and their electrocatalytic response. We will show that, by improving the mechanical properties of the NbC electrodes, microstructure and mechanical resilience can be obtained whilst maintaining high electro catalytic response. We also address the influence of other parameters such as conductivity and chemical composition on the overall performance of the thin film electrodes. Finally, we show that nanocomposite NbC electrodes are promising candidates towards HER , and furthermore, that the methodology presented here is suitable to produce other transition metal carbides (TM-C) with improved catalytic and mechanical properties.

  20. Study of high density polyethylene under UV irradiation or mechanical stress by fluorescence spectroscopy

    Douminge, L.

    2010-05-01

    Due to their diversity and their wide range of applications, polymers have emerged in our environment. For technical applications, these materials can be exposed to aggressive environment leading to an alteration of their properties. The effects of this degradation are linked to the concept of life duration, corresponding to the time required for a property to reach a threshold below which the material becomes unusable. Monitoring the ageing of polymer materials constitute a major challenge. Fluorescence spectroscopy is a technique able to provide accurate information concerning this issue. In this study, emphasis was placed on the use of fluorescence spectroscopy to study the phenomena involved in either the UV radiation or mechanical stresses of a polymer. In the case of high density polyethylene, the lack of intrinsic fluorescent signal leads to the use of a dye. This dye gives a fluorescent response depending on its microenvironment. All modifications in the macromolecular chain generate a shift of the fluorescent peak. This work can be dissociated in two major parts, on one hand the influence of UV aging on the fluorescent response and in another hand the influence of mechanical stresses. In the first part, complementary analyses like FTIR or DSC are used to correlate fluorescent results with known photo degradation mechanisms. The results show the great sensibility of the technique to the microstructural rearrangement in the polymer. In the second part, the dependence between the stress and the fluorescence emission gives opportunity to evaluate internal stresses in the material during cyclic solicitations. (author)