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Sample records for effective near-net shape

  1. Advanced Manufacturing Technologies (AMT): Advanced Near Net Shape Technology

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the Advanced Near Net Shape Technology (ANNST) project is to radically improve near net shape manufacturing methods from the current...

  2. Additive Manufacturing of Near-net Shaped Permanent Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M Parans [ORNL

    2016-07-26

    The technical objective of this technical collaboration phase I proposal is to fabricate near net-shaped permanent magnets using alloy powders utilizing direct metal deposition technologies at the ORNL MDF. Direct Manufacturing using the POM laser system was used to consolidate Nd2Fe14B (NdFeB) magnet powders into near net-shape parts efficiently and with virtually no wasted material as part of the feasibility study. We fabricated builds based on spherical NdFeB magnet particles. The results show that despite the ability to fabricate highly reactive materials in the laser deposition process, the magnetic coercivity and remanence of the NdFeB hard magnets is significantly reduced. X-ray powder diffraction in conjunction with electron microscopy showed that the material experienced a primary Nd2Fe17Bx solidification due to the undercooling effect (>60K). Consequently the presence of alpha iron phase resulted in deterioration of the build properties. Further optimization of the processing parameters is needed to maintain the Nd2Fe14B phase during fabrication.

  3. Near net shape of powder metallurgy rhenium parts

    International Nuclear Information System (INIS)

    Leonhardt, T.; Downs, J.

    2001-01-01

    In this paper, a description of the stages of processing necessary to produce a near-net shape (NNS) powder metallurgy (PM) rhenium component through the use of cold isostatic pressing (CIP) to form a complex shape will be explained. This method was primarily developed for the production of the 440 N and 490 N liquid apogee engine combustion chambers used in satellite positioning systems. The CIP to NNS process has been used in the manufacture and production of other rhenium aerospace components as well. Cold isostatic pressing (CIP) to a near net shape utilizing a one or two-part mandrel greatly reduces the quantity of rhenium required to produce the component, and also significantly reduces the number of secondary machining operations necessary to complete the manufacturing process. Further, the developments in near-net shape powder metallurgy rhenium manufacturing techniques have generated significant savings in the area of both time and budget. Overall, cost declined by as much as 35 % for the quantity of rhenium chambers, and manufacturing time was decreased by 30-40 %. The quantity of rhenium metal powder used to produce a rhenium chamber was reduced by approximately 70 %, with a subsequent reduction of nearly 50 % in secondary machining operation schedules. Thus, it is apparent that the overall savings provided by the production of near-net shape powder metallurgy rhenium components will be more than merely another aspect of any project involving high temperature applications, it will constitute significant benefit. (author)

  4. Manufacturing of thin walled near net shape iron castings

    DEFF Research Database (Denmark)

    Larsen, Per Leif

    2003-01-01

    The demand for near net shape thin walled iron castings is growing. This has several reasons, the main one is the need for lowering the fuel consumption of cars; the easiest way to do that is to lower the weight of the cars. The best way to do this was for a period of time believed...

  5. Near net-shape fabrication of hydroxyapatite glass composites

    NARCIS (Netherlands)

    Zhu, Q.; With, de G.; Dortmans, L.; Feenstra, F.

    2004-01-01

    Near net-shape fabrication of hydroxyapatite (HA) glass composites has been attempted by infiltrating a glass into porous HA performs. Main efforts were put to develop glasses that are chemically compatible with HA at elevated temperatures. After extensive investigations in the phosphate and

  6. Novel gelforming process for near net shape ceramic component production

    International Nuclear Information System (INIS)

    Franks, G.V.; Johnson, S.B.; Dunstan, D.E.

    2000-01-01

    A novel gelforming process for producing near-net shape ceramic components has been developed. A low viscosity, high volume fraction, ceramic suspension containing a small amount of bio-polymer is poured or injected into a mould. The suspension is gelled within the mould by a temperature activated crosslinking mechanism. The rheological behaviour of the body within the mould is changed from liquid-like to solid-like in a short period of time. The wet mechanical strength of the gelled bodies is sufficient to allow the body to be demoulded and handled without damaging the component. Near net shapes of complex geometry are formed in this way. The wet green body is then dried and densified using traditional methods. Potentially this process can be used to produce inexpensive reliable high strength ceramic components quickly and safely. Copyright (2000) The Australian Ceramic Society

  7. Near-Net Shape Powder Metallurgy Rhenium Thruster

    Science.gov (United States)

    Leonhardt, Todd; Hamister, Mark; Carlen, Jan C.; Biaglow, James; Reed, Brian

    2001-01-01

    This paper describes the development of a method to produce a near-net shape (NNS) powder metallurgy (PM) rhenium combustion chamber of the size 445 N (100 lbf) used in a high performance liquid apogee engine. These engines are used in low earth Orbit and geostationary orbit for satellite positioning systems. The developments in near-net shape powder metallurgy rhenium combustion chambers reported in this paper will reduce manufacturing cost of the rhenium chambers by 25 percent, and reduce the manufacturing time by 30 to 40 percent. The quantity of rhenium metal powder used to produce a rhenium chamber is reduced by approximately 70 percent and the subsequent reduction in machining schedule and costs is nearly 50 percent.

  8. Electrohydraulic Forming of Near-Net Shape Automotive Panels

    Energy Technology Data Exchange (ETDEWEB)

    Golovaschenko, Sergey F.

    2013-09-26

    The objective of this project was to develop the electrohydraulic forming (EHF) process as a near-net shape automotive panel manufacturing technology that simultaneously reduces the energy embedded in vehicles and the energy consumed while producing automotive structures. Pulsed pressure is created via a shockwave generated by the discharge of high voltage capacitors through a pair of electrodes in a liquid-filled chamber. The shockwave in the liquid initiated by the expansion of the plasma channel formed between two electrodes propagates towards the blank and causes the blank to be deformed into a one-sided die cavity. The numerical model of the EHF process was validated experimentally and was successfully applied to the design of the electrode system and to a multi-electrode EHF chamber for full scale validation of the process. The numerical model was able to predict stresses in the dies during pulsed forming and was validated by the experimental study of the die insert failure mode for corner filling operations. The electrohydraulic forming process and its major subsystems, including durable electrodes, an EHF chamber, a water/air management system, a pulse generator and integrated process controls, were validated to be capable to operate in a fully automated, computer controlled mode for forming of a portion of a full-scale sheet metal component in laboratory conditions. Additionally, the novel processes of electrohydraulic trimming and electrohydraulic calibration were demonstrated at a reduced-scale component level. Furthermore, a hybrid process combining conventional stamping with EHF was demonstrated as a laboratory process for a full-scale automotive panel formed out of AHSS material. The economic feasibility of the developed EHF processes was defined by developing a cost model of the EHF process in comparison to the conventional stamping process.

  9. Near net shape processing of zirconium or hafnium metals and alloys

    International Nuclear Information System (INIS)

    Evans, S.C.

    1992-01-01

    This patent describes a process for producing a metal shape. It comprises: plasma arc melting a metal selected from zirconium, hafnium and alloys thereof comprising at least about 90 w/o of these metals to form a liquid pool; pouring the metal form the pool into a mold to form a near net shape; and reducing the metal from its near net shape to a final size while maintaining the metal temperature below the alpha-beta transition temperature throughout the size reducing step

  10. Near net shape, low cost ceramic valves for advanced engine applications

    Energy Technology Data Exchange (ETDEWEB)

    Pidria, M.; Merlone, E.; Parussa, F. [Fiat Research Centre, Orbassano (Italy); Handelsman, J.; Gorodnev, A. [Ceracom Materials Ltd., Yavneh (Israel)

    2003-07-01

    Future gasoline and diesel engines with electro-hydraulic or electro-mechanical valve control systems require the development of lighter valves to achieve the best results in terms of increased performances, lower fuel consumption and overall efficiency. Ceramic materials can adequately satisfy the required mechanical and thermal properties, nevertheless they still lack as far as manufacturing costs are concerned. Objective of the work was the development of a low-cost forming and sintering process, to produce near-net shape ceramic valves thus requiring very low finishing operations and significantly minimizing material waste. Between available technical ceramic materials, silicon nitride has been chosen to replace conventional steels and Ni-based alloys for the exhaust valves application. The work was then devoted to (i) the selection of the best starting materials composition, taking into account the requirements of a cost effective and high volume production, (ii) the development of an innovative pressure-injection molding process to produce near-net shape parts via a thermosetting feedstock and (iii) the optimization of a proper pressure-less sintering route to obtain cost-competitive, real scale components with adequate final density and mechanical properties. (orig.)

  11. The potential of centrifugal casting for the production of near net shape uranium parts

    International Nuclear Information System (INIS)

    Robertson, E.

    1993-09-01

    This report was written to provide a detailed summary of a literature survey on the near net shape casting process of centrifugal casting. Centrifugal casting is one potential casting method which could satisfy the requirements of the LANL program titled Near Net Shape Casting of Uranium for Reduced Environmental, Safety and Health Impact. In this report, centrifugal casting techniques are reviewed and an assessment of the ability to achieve the near net shape and waste minimization goals of the LANL program by using these techniques is made. Based upon the literature reviewed, it is concluded that if properly modified for operation within a vacuum, vertical or horizontal centrifugation could be used to safely cast uranium for the production of hollow, cylindrical parts. However, for the production of components of geometries other than hollow tubes, vertical centrifugation could be combined with other casting methods such as semi-permanent mold or investment casting

  12. Near net shape forging of titanium alloy turbine blade

    International Nuclear Information System (INIS)

    Morita, Akiyasu; Hattori, Shigeo; Tani, Kazuhito; Takemura, Atsushi; Ashida, Yoshio

    1991-01-01

    The isothermal forging process has been developed to produce turbine blades made of near β Ti-alloy Ti-10V-2Fe-3Al. It is important to set the preform at the optimum position of the die in order to get a high precision product. The deformation analysis by using FEM is effective to determine the optimum position. And also it is necessary to avoid buckling induced by the restriction of axial elongation of the material. As a result, Ti-10V-2Fe-3Al blades could be formed precisely by using only one stage of forging, and machining was needed only at the root. The thickness of the oxide layer induced on the surface of the forged blade was only 70μm. The mechanical properties of Ti-10V-2Fe-3Al blades after forging and annealing were superior to those of Ti-6Al-4V blades and were nearly uniform across the length of the blades. (author)

  13. Near-net-shape fabrication of continuous Ag-Clad Bi-Based superconductors

    International Nuclear Information System (INIS)

    Lanagan, M. T. et al.

    1998-01-01

    We have developed a near-net-shape process for Ag-clad Bi-2212 superconductors as an alternative to the powder-in-tube process. This new process offers the advantages of nearly continuous processing, minimization of processing steps, reasonable ability to control the Bi-2212/Ag ratio, and early development of favorable texture of the Bi-2212 grains. Superconducting properties are discussed

  14. Determining casting defects in near-net shape casting aluminum parts by computed tomography

    Science.gov (United States)

    Li, Jiehua; Oberdorfer, Bernd; Habe, Daniel; Schumacher, Peter

    2018-03-01

    Three types of near-net shape casting aluminum parts were investigated by computed tomography to determine casting defects and evaluate quality. The first, second, and third parts were produced by low-pressure die casting (Al-12Si-0.8Cu-0.5Fe-0.9Mg-0.7Ni-0.2Zn alloy), die casting (A356, Al-7Si-0.3Mg), and semi-solid casting (A356, Al-7Si-0.3Mg), respectively. Unlike die casting (second part), low-pressure die casting (first part) significantly reduced the formation of casting defects (i.e., porosity) due to its smooth filling and solidification under pressure. No significant casting defect was observed in the third part, and this absence of defects indicates that semi-solid casting could produce high-quality near-net shape casting aluminum parts. Moreover, casting defects were mostly distributed along the eutectic grain boundaries. This finding reveals that refinement of eutectic grains is necessary to optimize the distribution of casting defects and reduce their size. This investigation demonstrated that computed tomography is an efficient method to determine casting defects in near-net shape casting aluminum parts.

  15. Ceramic Near-Net Shaped Processing Using Highly-Loaded Aqueous Suspensions

    Science.gov (United States)

    Rueschhoff, Lisa

    Ceramic materials offer great advantages over their metal counterparts, due to their lower density, higher hardness and wear resistance, and higher melting temperatures. However, the use of ceramics in applications where their properties would offer tremendous advantages are often limited due to the difficulty of forming them into complex and near-net shaped parts. Methods that have been developed to injection-mold or cast ceramics into more complicated shapes often use significant volume fractions of a carrier (often greater than 35 vol.% polymer), elevated temperature processing, or less-than-environmentally friendly chemicals where a complex chemical synthesis reaction must be timed perfectly for the approach to work. Furthermore, the continuing maturation of additive manufacturing methods requires a new approach for flowing/placing ceramic powders into useful designs. This thesis addresses the limitations of the current ceramic forming approaches by developing highly-stabilized and therefore high solids loading ceramic suspensions, with the requisite rheology for a variety of complex and near-net shaped forming techniques. Silicon nitride was chosen as a material of focus due to its high fracture toughness compared to other ceramic materials. Designing ceramic suspensions that are flowable at room temperature greatly simplifies processing as neither heating nor cooling are required during forming. Highly-loaded suspensions (>40 vol.%) are desired because all formed ceramic bodies have to be sintered to remove pores. Finally, using aqueous-based suspensions reduces any detrimental effect on the environment and tooling. The preparation of highly-loaded suspensions requires the development of a suitable dispersant through which particle-particle interactions are controlled. However, silicon nitride is difficult to stabilize in water due to complex surface and solution chemistry. In this study, aqueous silicon nitride suspensions up to 45 vol.% solids loading were

  16. Near-Net Shape Fabrication Using Low-Cost Titanium Alloy Powders

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David M. Bowden; Dr. William H. Peter

    2012-03-31

    The use of titanium in commercial aircraft production has risen steadily over the last half century. The aerospace industry currently accounts for 58% of the domestic titanium market. The Kroll process, which has been used for over 50 years to produce titanium metal from its mineral form, consumes large quantities of energy. And, methods used to convert the titanium sponge output of the Kroll process into useful mill products also require significant energy resources. These traditional approaches result in product forms that are very expensive, have long lead times of up to a year or more, and require costly operations to fabricate finished parts. Given the increasing role of titanium in commercial aircraft, new titanium technologies are needed to create a more sustainable manufacturing strategy that consumes less energy, requires less material, and significantly reduces material and fabrication costs. A number of emerging processes are under development which could lead to a breakthrough in extraction technology. Several of these processes produce titanium alloy powder as a product. The availability of low-cost titanium powders may in turn enable a more efficient approach to the manufacture of titanium components using powder metallurgical processing. The objective of this project was to define energy-efficient strategies for manufacturing large-scale titanium structures using these low-cost powders as the starting material. Strategies include approaches to powder consolidation to achieve fully dense mill products, and joining technologies such as friction and laser welding to combine those mill products into near net shape (NNS) preforms for machining. The near net shape approach reduces material and machining requirements providing for improved affordability of titanium structures. Energy and cost modeling was used to define those approaches that offer the largest energy savings together with the economic benefits needed to drive implementation. Technical

  17. Free-form processing of near-net shapes using directed light fabrication

    International Nuclear Information System (INIS)

    Thoma, D.J.; Lewis, G.K.; Milewski, J.O.; Nemec, R.B.

    1997-05-01

    Directed light fabrication (DLF) is a rapid fabrication process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, near-net shape, three-dimensional metal components from a computer generated solid model. Computer controls dictate the metal deposition pathways, and no preforms or molds are required to generate complex sample geometries with accurate and precise tolerances. The DLF technique offers unique advantages over conventional thermomechanical processes or thermal spray processes in that many labor and equipment intensive steps can be avoided to produce components with fully dense microstructures. Moreover, owing to the flexibility in power distributions of lasers, a variety of materials have been processed, ranging from aluminum alloys to tungsten, and including intermetallics such as Mo 5 Si 3 . Since DLF processing offers unique capabilities and advantages for the rapid fabrication of complex metal components, an examination of the microstructural development has been performed in order to define and optimize the processed materials. Solidification studies of DLF processing have demonstrated that a continuous liquid/solid interface is maintained while achieving high constant cooling rates that can be varied between 10 to 10 5 K s -1 and solidification growth rates ranging up to the 10 -2 m s -1

  18. Near Net Shape Fabrication Technology for Shape Memory Alloy Components, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This STTR Phase I effort proposes to develop an innovative, affordable processing route for larger-sized shape memory alloy (SMA) components. Despite significant...

  19. Life cycle assessment and sustainable engineering in the context of near net shape grown components: striving towards a sustainable way of future production.

    Science.gov (United States)

    Kämpfer, Christoph; Seiler, Thomas-Benjamin; Beger, Anna-Lena; Jacobs, Georg; Löwer, Manuel; Moser, Franziska; Reimer, Julia; Trautz, Martin; Usadel, Björn; Wormit, Alexandra; Hollert, Henner

    2017-01-01

    Technical product harvesting (TEPHA) is a newly developing interdisciplinary approach in which bio-based production is investigated from a technical and ecological perspective. Society's demand for ecologically produced and sustainably operable goods is a key driver for the substitution of conventional materials like metals or plastics through bio-based alternatives. Technical product harvesting of near net shape grown components describes the use of suitable biomass for the production of technical products through influencing the natural shape of plants during their growth period. The use of natural materials may show positive effects on the amount of non-renewable resource consumption. This also increases the product recyclability at the end of its life cycle. Furthermore, through the near net shape growth of biomass, production steps can be reduced. As a consequence such approaches may save energy and the needed resources like crude oil, coal or gas. The derived near net shape grown components are not only considered beneficial from an environmental point of view. They can also have mechanical advantages through an intrinsic topology optimization in contrast to common natural materials, which are influenced in their shape after harvesting. In order to prove these benefits a comprehensive, interdisciplinary scientific strategy is needed. Here, both mechanical investigations and life cycle assessment as a method of environmental evaluation are used.

  20. Near-net shape manufacture of B4C–Co and ZrC–Co composites by slip casting and pressureless sintering

    DEFF Research Database (Denmark)

    Ortiz, Angel L.; Leal, Victor Manuel Candelario; Moreno, Rodrigo

    2017-01-01

    Fabrication of near-net shaped B4C–Co and ZrC–Co composites by slip casting and pressureless sintering is described. It is shown how B4C–Co and ZrC–Co concentrated suspensions can be prepared by aqueous colloidal processing, and optimized (in terms of pH, deflocculant contents, and sonication tim...... is given for these observations, and general implications are discussed for the near-net shape manufacture of these and similar carbide-metal composites for use in engineering applications....

  1. Catalogue of X-Ray Texture Data for Al-Cu-Li Alloy 1460, 2090, 2096 and 2195 Near-Net-Shape Extrusions, Sheet and Plate

    Science.gov (United States)

    Hales, Stephen J.; Hafley, Robert A.; Alexa, Joel A.

    1998-01-01

    The effect of crystallographic texture on the mechanical properties of near-net-shape extrusions is of major interest ff these products are to find application in launch vehicle or aircraft structures. The objective of this research was to produce a catalogue containing quantitative texture information for extruded product, sheet and plate. The material characterized was extracted from wide, integrally stiffened panels fabricated from the Al-Cu-Li alloys 1460, 2090, 2096 and 2195. The textural characteristics of sheet and plate products of the same alloys were determined for comparison purposes. The approach involved using X-ray diffraction to generate pole figures in combination with orientation distribution function analysis. The data were compiled as a function of location in the extruded cross-sections and the variation in the major deformation- and recrystallization-related texture components was identified.

  2. Cost-Benefit Analysis for the Advanced Near Net Shape Technology (ANNST) Method for Fabricating Stiffened Cylinders

    Science.gov (United States)

    Ivanco, Marie L.; Domack, Marcia S.; Stoner, Mary Cecilia; Hehir, Austin R.

    2016-01-01

    Low Technology Readiness Levels (TRLs) and high levels of uncertainty make it challenging to develop cost estimates of new technologies in the R&D phase. It is however essential for NASA to understand the costs and benefits associated with novel concepts, in order to prioritize research investments and evaluate the potential for technology transfer and commercialization. This paper proposes a framework to perform a cost-benefit analysis of a technology in the R&D phase. This framework was developed and used to assess the Advanced Near Net Shape Technology (ANNST) manufacturing process for fabricating integrally stiffened cylinders. The ANNST method was compared with the conventional multi-piece metallic construction and composite processes for fabricating integrally stiffened cylinders. Following the definition of a case study for a cryogenic tank cylinder of specified geometry, data was gathered through interviews with Subject Matter Experts (SMEs), with particular focus placed on production costs and process complexity. This data served as the basis to produce process flowcharts and timelines, mass estimates, and rough order-of-magnitude cost and schedule estimates. The scalability of the results was subsequently investigated to understand the variability of the results based on tank size. Lastly, once costs and benefits were identified, the Analytic Hierarchy Process (AHP) was used to assess the relative value of these achieved benefits for potential stakeholders. These preliminary, rough order-of-magnitude results predict a 46 to 58 percent reduction in production costs and a 7-percent reduction in weight over the conventional metallic manufacturing technique used in this study for comparison. Compared to the composite manufacturing technique, these results predict cost savings of 35 to 58 percent; however, the ANNST concept was heavier. In this study, the predicted return on investment of equipment required for the ANNST method was ten cryogenic tank barrels

  3. Microstructure and mechanical properties of hypo/hyper-eutectic Al-Si alloys synthesized using a near-net shape forming technique

    International Nuclear Information System (INIS)

    Gupta, M.; Ling, S.

    1999-01-01

    In the present study, three aluminum-silicon alloys containing 7, 10 and 19 wt % silicon were synthesized using a novel technique commonly known as disintegrated melt deposition technique. The results following processing revealed that a yield of at least 80% can be achieved after defacing the shrinkage cavity from the as-processed ingots. Microstructural characterization studies conducted on the as-processed samples revealed an increase in the volume fraction of porosity with an increase in silicon content. Porosity levels of 1.07, 1.51 and 2.65% attained in the case of Al-7Si, Al-10Si, and Al-19Si alloys indicates the near-net shape forming capability of the disintegrated melt deposition technique. The results of aging studies conducted on the aluminum-silicon alloys revealed similar aging kinetics irrespective of different silicon content. Results of ambient temperature mechanical tests demonstrate an increase in matrix microhardness and 0.2% yield stress and decrease in ductility with an increase in silicon content in aluminum. Furthermore, the results of an attempt to investigate the effect of extrusion on Al-19Si alloy revealed that the extrusion process significantly assists in reducing porosity and improving microstructural uniformity, 0.2% yield strength, ultimate tensile strength and ductility when compared to the as-processed Al-19Si alloy. The results of microstructural characterization and mechanical properties of aluminum-silicon alloys were finally correlated with the amount of silicon in aluminum and secondary processing technique. (orig.)

  4. Development of a near-net-shape casting technology for the U-6Nb alloy. Part 1: Materials characterization, experiment design, and model construction

    International Nuclear Information System (INIS)

    Taylor, M.J.; Keeney, J.A.; Wendel, M.W.; Demint, A.L.

    1997-01-01

    The Oak Ridge Y-12 Plant (Y-12) is conducting highly coupled experimental and numerical studies to develop the technology needed to produce near-net-shape (NNS)-cast uranium-6 wt% niobium (U-6Nb) components which have a controlled carbon content. Current activities are focused on defining mechanical and metallurgical properties of cast material; experimental studies to define NNS casting, carbide particle flotation, and immersion-quench physics; and developing the numerical models needed to support the optimized design of NNS components. This paper summarizes the material characterization, experiment design, and model development activities

  5. A novel one-pot process for near-net-shape fabrication of open-porous resorbable hydroxyapatite/protein composites and in vivo assessment

    International Nuclear Information System (INIS)

    Mueller, Berit; Koch, Dietmar; Lutz, Rainer; Schlegel, Karl A.; Treccani, Laura; Rezwan, Kurosch

    2014-01-01

    We present a mild one-pot freeze gelation process for fabricating near-net, complex-shaped hydroxyapatite scaffolds and to directly incorporate active proteins during scaffold processing. In particular, the direct protein incorporation enables a simultaneous adjustment and control of scaffold microstructure, porosity, resorbability and enhancement of initial mechanical and handling stability. Two proteins, serum albumin and lysozyme, are selected and their effect on scaffold stability and microstructure investigated by biaxial strength tests, electron microscopy, and mercury intrusion porosimetry. The resulting hydroxyapatite/protein composites feature adjustable porosities from 50% to 70% and a mechanical strength ranging from 2 to 6 MPa comparable to that of human spongiosa without any sintering step. Scaffold degradation behaviour and protein release are assessed by in vitro studies. A preliminary in vivo assessment of scaffold biocompatibility and resorption behaviour in adult domestic pigs is discussed. After implantation, composites were resorbed up to 50% after only 4 weeks and up to 65% after 8 weeks. In addition, 14% new bone formation after 4 weeks and 37% after 8 weeks were detected. All these investigations demonstrate the outstanding suitability of the one-pot-process to create, in a customisable and reliable way, biocompatible scaffolds with sufficient mechanical strength for handling and surgical insertion, and for potential use as biodegradable bone substitutes and versatile platform for local drug delivery. - Highlights: • We present a one-pot process for directly incorporating protein into HAp scaffolds. • The effect of two model proteins, BSA and LSZ, on scaffold properties is analysed. • HAp/protein scaffolds feature a mechanical strength comparable to human spongiosa. • BSA incorporation in scaffolds leads to strength increase despite porosity increment. • New bone formation in-vivo exceeds established xenograft bone substitutes

  6. Plasma spray formed near-net-shape MoSi2-Si3N4 bulk nanocomposites-structure property evaluation

    International Nuclear Information System (INIS)

    Hong, S.J.; Viswanathan, V.; Rea, K.; Patil, S.; Deshpande, S.; Georgieva, P.; McKechnie, T.; Seal, S.

    2005-01-01

    This article, for the first time, presents the challenges toward the successful consolidation of near-net-shape bulk MoSi 2 -Si 3 N 4 -SiC nanocomposite using plasma spray forming. A detailed characterization of the spray formed bulk nanocomponent has been performed using optical microscopy (OM), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and Vickers hardness testing. Vickers hardness (900 Hv) and fracture toughness (∼>5 MPa m 1/2 ) of the nanocomposite showed a little deviation from the expected, which might be due to the difference in the particle (Si 3 N 4 ) size and their distribution in the MoSi 2 matrix as a function of component thickness. Relatively higher hardness is attributed to the retention of the nanostructure in the composite. In addition, the as fabricated bulk nanocomposite showed enhanced oxidation resistance

  7. Additional grain refinement in recrystallization controlled rolling of Ti-microalloyed steels processed by near-net-shape casting technology

    International Nuclear Information System (INIS)

    Arribas, M.; Lopez, B.; Rodriguez-Ibabe, J.M.

    2008-01-01

    This paper analyzes the recrystallization kinetics in Ti-microalloyed steels processed using 'beam blank' casting technology. The faster solidification rates associated with this technology brings a finer precipitation of TiN particles which are very effective in controlling austenite grain growth during hot working. Furthermore, these small precipitates have been shown to delay static and dynamic recrystallization. The finer the precipitates the higher the delay in recrystallization. Nevertheless, beyond particle size and distribution, the level of delay is very dependent on microstructure (above all austenite grain size) and deformation conditions (strain and temperature). This paper studies the effects of this recrystallization delay on the microstructure evolution during hot rolling. Special attention was paid to the study of the occurrence of partial recrystallization during the final stages of rolling, which could lead to the presence of mixed microstructures before transformation. The possibility of achieving an additional austenite grain size refinement prior to transformation was evaluated

  8. Near-Net Forging Technology Demonstration Program

    Science.gov (United States)

    Hall, I. Keith

    1996-01-01

    Significant advantages in specific mechanical properties, when compared to conventional aluminum (Al) alloys, make aluminum-lithium (Al-Li) alloys attractive candidate materials for use in cryogenic propellant tanks and dry bay structures. However, the cost of Al-Li alloys is typically five times that of 2219 aluminum. If conventional fabrication processes are employed to fabricate launch vehicle structure, the material costs will restrict their utilization. In order to fully exploit the potential cost and performance benefits of Al-Li alloys, it is necessary that near-net manufacturing methods be developed to off-set or reduce raw material costs. Near-net forging is an advanced manufacturing method that uses elevated temperature metal movement (forging) to fabricate a single piece, near-net shape, structure. This process is termed 'near-net' because only a minimal amount of post-forge machining is required. The near-net forging process was developed to reduce the material scrap rate (buy-to-fly ratio) and fabrication costs associated with conventional manufacturing methods. The goal for the near-net forging process, when mature, is to achieve an overall cost reduction of approximately 50 percent compared with conventional manufacturing options for producing structures fabricated from Al-Li alloys. This NASA Marshall Space Flight Center (MSFC) sponsored program has been a part of a unique government / industry partnership, coordinated to develop and demonstrate near-net forging technology. The objective of this program was to demonstrate scale-up of the near-net forging process. This objective was successfully achieved by fabricating four integrally stiffened, 170- inch diameter by 20-inch tall, Al-Li alloy 2195, Y-ring adapters. Initially, two 2195 Al-Li ingots were converted and back extruded to produce four cylindrical blockers. Conventional ring rolling of the blockers was performed to produce ring preforms, which were then contour ring rolled to produce

  9. Near Net Manufacturing Using Thin Gage Friction Stir Welding

    Science.gov (United States)

    Takeshita, Jennifer; Potter, David; Holquin, Michael

    2006-01-01

    Friction Stir Welding (FSW) and near net spin forming of FSW aluminumn blanks were investigated for large-scale pressure vessel applications. With a specific focus on very thin gage 2xxx and 7xxx aluminum alloys, the program concentrated on the following: the criteria used for material selection, a potential manufacturing flow, and the effectiveness and associated risks of near net spin forming. Discussion will include the mechanical properties of the friction stir welds and the parent material from before and after the spin forming process. This effort was performed under a NASA Space Exploration initiative focused on increasing the affordability, reliability and performance of pressure vessels larger than 10 ft. diameter.

  10. Automated Defect Recognition as a Critical Element of a Three Dimensional X-ray Computed Tomography Imaging-Based Smart Non-Destructive Testing Technique in Additive Manufacturing of Near Net-Shape Parts

    Directory of Open Access Journals (Sweden)

    Istvan Szabo

    2017-11-01

    Full Text Available In this paper, a state of the art automated defect recognition (ADR system is presented that was developed specifically for Non-Destructive Testing (NDT of powder metallurgy (PM parts using three dimensional X-ray Computed Tomography (CT imaging, towards enabling online quality assurance and enhanced integrity confidence. PM parts exhibit typical defects such as microscopic cracks, porosity, and voids, internal to components that without an effective detection system, limit the growth of industrial applications. Compared to typical testing methods (e.g., destructive such as metallography that is based on sampling, cutting, and polishing of parts, CT provides full coverage of defect detection. This paper establishes the importance and advantages of an automated NDT system for the PM industry applications with particular emphasis on image processing procedures for defect recognition. Moreover, the article describes how to establish a reference library based on real 3D X-ray CT images of net-shape parts. The paper follows the development of the ADR system from processing 2D image slices of a measured 3D X-ray image to processing the complete 3D X-ray image as a whole. The introduced technique is successfully integrated into an automated in-line quality control system highly sought by major industry sectors in Oil and Gas, Automotive, and Aerospace.

  11. Optimisation of Forming Parameters to Reach Near Net Shape

    DEFF Research Database (Denmark)

    Ravn, Bjarne Gottlieb; Wanheim, Tarras

    2000-01-01

    Demands to the manufacturing industry have always been that the overall production expenses for a given component should be decreased. In the metal forming area, one way to reduce the expenses is to increase the complexity of the component and to reduce the number of steps in the production and t...

  12. Near net shape forming unsing semi-solid metal forming

    CSIR Research Space (South Africa)

    Govender, G

    2005-10-01

    Full Text Available (NRC) – UBE • Semi-Solid Rheocasting (SSR) – MIT • New Semi-Solid Casting – Hitachi • Sub-liquidus Casting (SLC) –JLH Technologies & THT Presses • Slurry on Demand (SoD) – AEMP 2005 Contech –USA Citation – USA Intermet – USA Stampal - ITALY... Stampal - producing engine brackets for Fiat PUNTO 50000 pcs per month New Rheocasting (NRC) - UBE 2005 Semi-Solid Rheocasting – MIT 2005 Hitachi Process 2005 SLC Process 2005 Advantages and Disadvantages of Rheocasting Advantages Disadvantages...

  13. Advanced Near Net Shape Technology (ANNST) - Integrally Stiffened Cylinder (ISC)

    Data.gov (United States)

    National Aeronautics and Space Administration — Machined/welded construction of launch vehicle cryotanks is expensive, heavy, and risky. The current state of the art manufacturing of launch vehicles contributes to...

  14. Near net-shape fabrication of alumina glass composites

    NARCIS (Netherlands)

    Zhu, Q.; With, de G.; Dortmans, L.J.M.G.; Feenstra, F.

    2005-01-01

    The purpose of the present study is to fabricate alumina glass composites by melt infiltration with better dimensional control through reducing both the presintering and infiltration temperature. Main efforts were put to develop glasses that are chemically compatible with alumina. After extensive

  15. Shape memory effect alloys

    International Nuclear Information System (INIS)

    Koshimizu, S.

    1992-01-01

    Although the pseudo- or super-elasticity phenomena and the shape memory effect were known since the 1940's, the enormous curiosity and the great interest to their practical applications emerged with the development of the NITINOL alloy (Nickel-Titanium Naval Ordance Laboratory) by the NASA during the 1960's. This fact marked the appearance of a new class of materials, popularly known as shape memory effect alloys (SMEA). The objective of this work is to present a state-of-the-art of the development and applications for the SMEA. (E.O.)

  16. Examples of Nearly Net Zero Energy Buildings Through One-Step and Stepwise Retrofits

    DEFF Research Database (Denmark)

    Galiotto, Nicolas; Heiselberg, Per; Knudstrup, Mary-Ann

    2012-01-01

    This paper presents the review of eight single-family house retrofit projects. The main objective is to collect and classify several approaches to nearly net zero energy building retrofitting. The selection has been made on the capacity of reaching a nearly net zero energy level via a one......-step or stepwise retrofit process. The review work is part of a more global Ph.D. project and is used as one of the basement of the future research work. The considered approaches have been sorted in two categories. The first approach has a very high use of energy conservation measures and low use of renewable...... energy production measures. The second approach has a lower use of energy conservation measures (but still high compared to a traditional renovation) and a higher use of renewable energy production measures. A third approach to nearly net zero energy building renovation exists but has not been considered...

  17. Semi-solid near-net shape rheocasting of heat treatable wrought aluminum alloys

    CSIR Research Space (South Africa)

    Curle, UA

    2010-09-01

    Full Text Available Flexibility of the CSIR-RCS, induction stirring with simultaneous air cooling process, in combination with high pressure die casting is successfully demonstrated by semi-solid rheocasting of plates performed on commercial 2024, 6082 and 7075 wrought...

  18. Near-net shape manufacturing of miniature spur gears by wire spark erosion machining

    CERN Document Server

    Gupta, Kapil

    2016-01-01

    This work describes an experimental investigation with the aim to evaluate and establish wire spark erosion machining (WSEM) as a viable alternative for high quality miniature gear manufacturing. External spur type miniature brass (ASTM 858) gears with 12 teeth, 9.8 mm outside diameter and 5 mm face width were manufactured by WSEM. The research work was accomplished in four distinct experimental stages viz., preliminary, pilot, main and confirmation. The aim, scope and findings of each stage are progressively presented and discussed. In essence, the investigation found that it was possible to manufacture miniature gears to high quality by using WSEM. Gears up to DIN 5 quality with a good surface finish (1.2 µm average roughness) and satisfactory surface integrity were achieved. The results suggest that WSEM should be considered a viable alternative to conventional miniature gear manufacturing techniques and that in some instances it may even be superior. This work will prove useful to researchers and profess...

  19. Finite element simulation of HIP-process to produce 3d near net shape parts

    International Nuclear Information System (INIS)

    Zadeh, M.K.

    1996-01-01

    One of the major problems when producing powder metallurgy parts through hot isostatic pressing (HIP) is the non homogeneous shrinkage of HIP-capsule during the process. This leads to time and cost consuming machining of the HIP parts. In order to reduce the machining to a minimum, one can try to simulate the HIP-process by means of numerical methods. Hereby, the part distortion can be predicted, and hence a new HIP-capsule can be designed in such a way to prevent the distortion partly or even completely. In the following, a finite element method is used, on one hand, to simulate part shrinkage during HIP process; on the other hand a method is integrated in this simulation to optimize the HIP-capsule geometry. For the determination of material dependent parameters, a mixture of theoretical and experimental methods is used. Results of simulation are verified for a complex 3d HIP part out of TiAl6V4

  20. Ambient Processing for In-Situ Selective Reinforcement (ISSR) of Near Net Shape Structures

    Data.gov (United States)

    National Aeronautics and Space Administration — Use AMPB’s laboratory-scale rolling mill to simulate the dynamic conditions associated with metallic structure forming and fabrication methods. Use aerospace...

  1. Technologische Entwicklung zur Herstellung von near-net shape Niederdruckturbinenschaufeln aus dem intermetallischen Werkstoff Titanaluminid im Feinguss

    OpenAIRE

    Kättlitz, Oliver

    2014-01-01

    Global air traffic is predicted to rise long-term (2012-2031) at an annual rate of almost 5%, signifying a 100% increase in passenger and freight volumes over the next 15-20 years. In view of the environmental consequences, 2011 saw the release by the EU of Vision Flightpath 2050, which sets ambitious goals for pollution and noise reduction (including a 75% reduction in CO2, taking the year 2000 as benchmark). A potential CO2 emission saving in the order of 15-20% is achievable simply by step...

  2. EFFECTS OF SLOPE SHAPES ON SOIL EROSION

    Directory of Open Access Journals (Sweden)

    Hüseyin ŞENSOY, Şahin PALTA

    2009-01-01

    Full Text Available Water is one of the most important erosive forces. A great number of factors also play a role in erosion process and slope characteristic is also one of them. The steepness and length of the slope are important factors for runoff and soil erosion. Another slope factor that has an effect on erosion is the shape of the slope. Generally, different erosion and runoff characteristics exist in different slopes which can be classified as uniform, concave, convex and complex shape. In this study, the effects of slope shape on erosion are stated and emphasized by taking similar researches into consideration.

  3. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa

    2015-12-29

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  4. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa; Fahad, Hossain M.; Smith, Casey E.; Rojas, Jhonathan Prieto

    2015-01-01

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  5. Research and industrialization of near-net rolling technology used in shaft parts

    Science.gov (United States)

    Hu, Zhenghuan; Wang, Baoyu; Zheng, Zhenhua

    2018-03-01

    Shaft part rolling is an efficient and green nearnet shaping technology offering many advantages, including high production efficiency, high material utilization rate, high product quality, and excellent production environment. In this paper, the features of shaft part rolling are introduced along with the working principles of two main shaft part rolling technologies, namely, cross wedge rolling (CWR) and skew rolling (SR). In relation to this technology, some R&D achievements gained by the University of Science and Technology Beijing are summarized. Finally, the latest developments in shaft part rolling are presented, including SR steel balls, precise forming of camshaft blank by CWR, SR phosphorous copper balls at room temperature, and CWR hollow axle sleeve. Although the shaft part rolling technology has been widely used in China, it only accounts for about 15% of applicable parts at present. Nevertheless, this technology has broad application prospects.

  6. Thermoinduced plastic flow and shape memory effects

    Directory of Open Access Journals (Sweden)

    Xiao Heng

    2011-01-01

    Full Text Available We propose an enhanced form of thermocoupled J2-flow models of finite deformation elastoplasticity with temperature-dependent yielding and hardening behaviour. The thermomechanical constitutive structure of these models is rendered free and explicit in the rigorous sense of thermodynamic consistency. Namely, with a free energy function explicitly introduced in terms of almost any given form of the thermomechanical constitutive functions, the requirements from the second law are identically fulfilled with positive internal dissipation. We study the case when a dependence of yielding and hardening on temperature is given and demonstrate that thermosensitive yielding with anisotropic hardening may give rise to appreciable plastic flow either in a process of heating or in a cyclic process of heating/cooling, thus leading to the findings of one- and two-way thermoinduced plastic flow. We then show that such theoretical findings turn out to be the effects found in shape memory materials, such as one- and two-way memory effects. Thus, shape memory effects may be explained to be thermoinduced plastic flow resulting from thermosensitive yielding and hardening behaviour. These and other relevant facts may suggest that, from a phenomenological standpoint, thermocoupled elastoplastic J2-flow models with thermosensitive yielding and hardening may furnish natural, straightforward descriptions of thermomechanical behaviour of shape memory materials.

  7. Hydrogen Economy Model for Nearly Net-Zero Cities with Exergy Rationale and Energy-Water Nexus

    Directory of Open Access Journals (Sweden)

    Birol Kılkış

    2018-05-01

    Full Text Available The energy base of urban settlements requires greater integration of renewable energy sources. This study presents a “hydrogen city” model with two cycles at the district and building levels. The main cycle comprises of hydrogen gas production, hydrogen storage, and a hydrogen distribution network. The electrolysis of water is based on surplus power from wind turbines and third-generation solar photovoltaic thermal panels. Hydrogen is then used in central fuel cells to meet the power demand of urban infrastructure. Hydrogen-enriched biogas that is generated from city wastes supplements this approach. The second cycle is the hydrogen flow in each low-exergy building that is connected to the hydrogen distribution network to supply domestic fuel cells. Make-up water for fuel cells includes treated wastewater to complete an energy-water nexus. The analyses are supported by exergy-based evaluation metrics. The Rational Exergy Management Efficiency of the hydrogen city model can reach 0.80, which is above the value of conventional district energy systems, and represents related advantages for CO2 emission reductions. The option of incorporating low-enthalpy geothermal energy resources at about 80 °C to support the model is evaluated. The hydrogen city model is applied to a new settlement area with an expected 200,000 inhabitants to find that the proposed model can enable a nearly net-zero exergy district status. The results have implications for settlements using hydrogen energy towards meeting net-zero targets.

  8. Matter Density Profile Shape Effects at DUNE

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Kevin J. [Northwestern U.; Parke, Stephen J. [Fermilab

    2018-02-19

    Quantum mechanical interactions between neutrinos and matter along the path of propagation, the Wolfenstein matter effect, are of particular importance for the upcoming long-baseline neutrino oscillation experiments, specifically the Deep Underground Neutrino Experiment (DUNE). Here, we explore specifically what about the matter density profile can be measured by DUNE, considering both the shape and normalization of the profile between the neutrinos' origin and detection. Additionally, we explore the capability of a perturbative method for calculating neutrino oscillation probabilities and whether this method is suitable for DUNE. We also briefly quantitatively explore the ability of DUNE to measure the Earth's matter density, and the impact of performing this measurement on measuring standard neutrino oscillation parameters.

  9. The Effect of Shape Memory on Red Blood Cell Motions

    Science.gov (United States)

    Niu, Xiting; Shi, Lingling; Pan, Tsorng-Whay; Glowinski, Roland

    2013-11-01

    An elastic spring model is applied to study the effect of the shape memory on the motion of red blood cell in flows. In shear flow, shape memory also plays an important role to obtain all three motions: tumbling, swinging, and tank-treading. In Poiseuille flow, cell has an equilibrium shape as a slipper or parachute depending on capillary number. To ensure the tank-treading motion while in slippery shape, a modified model is proposed by introducing a shape memory coefficient which describes the degree of shape memory in cells. The effect of the coefficient on the cell motion of red blood cell will be presented.

  10. Shape memory polymer hybrids of SBS/dl-PLA and their shape memory effects

    International Nuclear Information System (INIS)

    Zhang, Heng; Chen, Zhi; Zheng, Zheng; Zhu, Xiaomin; Wang, Haitao

    2013-01-01

    The hybrids of styrene-butadiene-styrene tri-block copolymer (SBS) and amorphous poly(dl-lactic acid) (dl-PLA) are found to exhibit shape memory effects, which gives an example of a dual-domain shape memory system consisting of an elastic domain and a thermo-switch domain. The dual-domain manner in this hybrid is studied by means of differential scanning calorimetry (DSC) and scanning electron microscope (SEM). Subsequently, the tensile test clarifies the interactions of the two domains on shape memory effects. As an elastic domain, SBS offers good shape recovery when its content exceeds 50 wt%. As a thermo-switch domain, dl-PLA triggers the shape memory effect at ca. 55 °C and offers good shape fixing when the content exceeds 30 wt%. An easy-to-do and easy-to-know feature of the hybrid is that the optimization of shape memory effect can be achieved by generating bicontinous phases of SBS and dl-PLA, in which the dl-PLA content ranges from 30 to 70 wt%. -- Highlights: ► The composite materials of SBS and amorphous dl-PLA were prepared by blending. ► A continuous domain was observed with the increasing content of dl-PLA. ► The composites exhibited shape memory effects.

  11. Chemical exchange effects in spectral line shapes

    International Nuclear Information System (INIS)

    Diaz, M.A.; Veguillas, J.

    1990-01-01

    A theory of spectral-line shapes has been extended to the case in which relaxation broadening may be influenced by reactive interactions. This extension is valid for gaseous systems in the same way it is valid for condensed media, and particularly, for such chemical mechanisms as isomerizations. The dependence of the spectral rate on the chemical exchange rate is clarified. Finally, a discussion concerning the above aspects and their applications has been included. (author)

  12. Magnetic properties of elliptical and stadium-shaped nanoparticles: Effect of the shape anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Corona, R.M. [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Altbir, D. [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Escrig, J., E-mail: jescrigm@gmail.com [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

    2012-11-15

    Elliptical and stadium-shaped nanoparticles as a function of their geometry have been investigated using numerical simulations. The effect of the shape anisotropy of the particles on coercivity and remanence together with the angular dependence of the remanence and coercivity are addressed. Our results demonstrate that the stadium-shaped particles have many of the outstanding properties of elliptical particles, but also have unique properties, such that the coercivity and remanence remain stable for a wide range of geometry parameters, and exhibit a peculiar angular dependence in the coercivity. These properties suggest that they can be useful for applications in the area of magnetic recording systems. - Highlights: Black-Right-Pointing-Pointer Coercivity and remanence are strongly affected by the shape anisotropy of the particles. Black-Right-Pointing-Pointer Coercivities for ellipses are nearly three times the obtained for stadium-shaped particles. Black-Right-Pointing-Pointer Elliptical particles with {delta}{<=}0.6, the hystereses resemble the square loops of wires. Black-Right-Pointing-Pointer An anhisteretic behavior appears for {theta}=90 Degree-Sign for elliptical particles, which do not appear in stadium-shaped particles. Black-Right-Pointing-Pointer Stadium-shaped particles have unique properties that allow us to suggest them for applications.

  13. Magnetic properties of elliptical and stadium-shaped nanoparticles: Effect of the shape anisotropy

    International Nuclear Information System (INIS)

    Corona, R.M.; Altbir, D.; Escrig, J.

    2012-01-01

    Elliptical and stadium-shaped nanoparticles as a function of their geometry have been investigated using numerical simulations. The effect of the shape anisotropy of the particles on coercivity and remanence together with the angular dependence of the remanence and coercivity are addressed. Our results demonstrate that the stadium-shaped particles have many of the outstanding properties of elliptical particles, but also have unique properties, such that the coercivity and remanence remain stable for a wide range of geometry parameters, and exhibit a peculiar angular dependence in the coercivity. These properties suggest that they can be useful for applications in the area of magnetic recording systems. - Highlights: ► Coercivity and remanence are strongly affected by the shape anisotropy of the particles. ► Coercivities for ellipses are nearly three times the obtained for stadium-shaped particles. ►Elliptical particles with δ≤0.6, the hystereses resemble the square loops of wires. ► An anhisteretic behavior appears for θ=90° for elliptical particles, which do not appear in stadium-shaped particles. ► Stadium-shaped particles have unique properties that allow us to suggest them for applications.

  14. Shape memory effect and super elasticity. Its dental applications.

    Science.gov (United States)

    Kotian, R

    2001-01-01

    The shape memory alloys are quite fascinating materials characterized by a shape memory effect and super elasticity which ordinary metals do not have. This unique behaviour was first found in a Au-47.5 at % Cd alloy in 1951, and was published in 1963 by the discovery of Ti-Ni alloy. Shape memory alloys now being practically used as new functional alloys for various dental and medical applications.

  15. The quintuple-shape memory effect in electrospun nanofiber membranes

    Science.gov (United States)

    Zhang, Fenghua; Zhang, Zhichun; Liu, Yanju; Lu, Haibao; Leng, Jinsong

    2013-08-01

    Shape memory fibrous membranes (SMFMs) are an emerging class of active polymers, which are capable of switching from a temporary shape to their permanent shape upon appropriate stimulation. Quintuple-shape memory membranes based on the thermoplastic polymer Nafion, with a stable fibrous structure, are achieved via electrospinning technology, and possess a broad transition temperature. The recovery of multiple temporary shapes of electrospun membranes can be triggered by heat in a single triple-, quadruple-, quintuple-shape memory cycle, respectively. The fiber morphology and nanometer size provide unprecedented design flexibility for the adjustable morphing effect. SMFMs enable complex deformations at need, having a wide potential application field including smart textiles, artificial intelligence robots, bio-medical engineering, aerospace technologies, etc in the future.

  16. The quintuple-shape memory effect in electrospun nanofiber membranes

    International Nuclear Information System (INIS)

    Zhang, Fenghua; Zhang, Zhichun; Lu, Haibao; Leng, Jinsong; Liu, Yanju

    2013-01-01

    Shape memory fibrous membranes (SMFMs) are an emerging class of active polymers, which are capable of switching from a temporary shape to their permanent shape upon appropriate stimulation. Quintuple-shape memory membranes based on the thermoplastic polymer Nafion, with a stable fibrous structure, are achieved via electrospinning technology, and possess a broad transition temperature. The recovery of multiple temporary shapes of electrospun membranes can be triggered by heat in a single triple-, quadruple-, quintuple-shape memory cycle, respectively. The fiber morphology and nanometer size provide unprecedented design flexibility for the adjustable morphing effect. SMFMs enable complex deformations at need, having a wide potential application field including smart textiles, artificial intelligence robots, bio-medical engineering, aerospace technologies, etc in the future. (paper)

  17. Effect of pinhole shape on projection resolution

    International Nuclear Information System (INIS)

    Johnson, L C; Metzler, S D; Moore, S C

    2016-01-01

    We are designing a dual-resolution pre-clinical SPECT system based on square-pinhole apertures for use in applications with a small field-of-view (FOV), such as cardiac imaging of mice. Square pinholes allow for increased sensitivity due to more efficient projection tiling on the detector compared to circular pinholes. Aperture fabrication techniques cannot produce a perfect square, giving the square pinholes some amount of roundedness at the corners. This work investigates how this roundedness affects the physical properties of projection images in terms of spatial resolution. Different pinhole full-acceptance angles and roundedness values were simulated. To facilitate a fair comparison, properties of the non-square pinholes were manipulated to yield pinholes with approximately the same sensitivity (to within 0.1%) and FOV (to within 0.5%) as those of the square pinholes, subsequently referred to as matched apertures. The aperture size (flat-to-flat edge length) of each non-square aperture was increased until its sensitivity was approximately equal to that of the square pinhole. Next, the full acceptance angle was increased until the FOV of each non-square aperture was approximately equivalent to that of the square pinhole. Sensitivity was calculated to include both the geometric and penetrative sensitivity of a point source, as well as the packing faction of the multi-pinhole collimator. Using the sensitivity-matched and FOV-matched apertures, spatial resolution was estimated. For the 0.3 mm, 0.5 mm, and 1 mm edge-length square apertures studied, the full-width at half-maximum widened as pinhole shape changed from square to circle, while full-width tenth-maximum showed little change. These results indicate that a perfect square pinhole shape is more desirable than a rounded-square pinhole with regard to spatial resolution when sensitivity and FOV-matched pinholes are compared. (paper)

  18. Powder metallurgy of NiTi-alloys with defined shape memory properties

    International Nuclear Information System (INIS)

    Bram, M.; Ahmad-Khanlou, A.; Buchkremer, H.P.; Stoever, D.

    2001-01-01

    The aim of the present work is the development of fabrication processes for NiTi shape memory alloys by powder metallurgical means. The starting materials used were prealloyed powders as well as elemental powder mixtures. Three techniques seem to be very promising for shaping of NiTi compacts. Hot Isostatic Pressing (HIP) has been examined for the production of dense semi-finished components. A promising technique for the production of dense and porous coatings with an increased wear resistance is Vacuum Plasma Spraying (VPS). Metal Injection Moulding (MIM) is especially suitable for near-net shape fabrication of small components with a complex geometry considering that large numbers of units have to be produced for compensating high tool and process costs. Subsequently, thermal treatments are required to establish defined shape memory properties. The reproducibility and stability of the shape memory effect are main aspects thinking about a production of NiTi components in an industrial scale. (author)

  19. Near-net-shape 95W-3.5Ni-1.5Fe thin-walled products produced by plasma spray forming

    International Nuclear Information System (INIS)

    Wang, Y.M.; Xiong, X.; Min, X.B.; Xie, L.; Zheng, F.

    2010-01-01

    Tungsten heavy alloy 95W-3.5Ni-1.5Fe (in wt.%) refractory metallic thin-walled products (diameter ≤100 mm, length ≤150 mm and wall thickness ≤5 mm) were produced using plasma spray forming (PSF) covered in argon atmosphere at a pressure of 1.01 x 10 5 Pa followed by vacuum liquid phase sintering at 1465, 1485 and 1500 deg. C for 90 min, respectively. A lamellar structure consisting of vertical columnar grains and some fine particles was found in PSF deposits. Relative density of the deposits was about 87.70% with poor mechanical property. Upon vacuum liquid phase sintering, their density and property have been improved significantly. The microstructures of PSF deposits before and after vacuum sintering were found to consist with tungsten and (Ni, Fe)-rich phase. Volume fraction of (Ni, Fe)-rich phase was decreased due to vaporization that occurred in plasma spraying and vacuum liquid phase sintering. Their fracture surfaces were dominated by intergranular rupture. The lamellar structure remained in the deposits during early stages of sintering (solid state sintering and initial of liquid phase sintering). Particle rearrangement and rapid densification of the deposits did not occur until the surface of tungsten particles being modified and changed into spheroids by solution and precipitation. In the end, the PSF deposits have been transformed from lamellar structure into two phase composites with dispersed spheroidal tungsten grains embedded in a continuous network of (Ni, Fe)-rich phase.

  20. Experimental effective shape control of a powered transfemoral prosthesis.

    Science.gov (United States)

    Gregg, Robert D; Lenzi, Tommaso; Fey, Nicholas P; Hargrove, Levi J; Sensinger, Jonathon W

    2013-06-01

    This paper presents the design and experimental implementation of a novel feedback control strategy that regulates effective shape on a powered transfemoral prosthesis. The human effective shape is the effective geometry to which the biological leg conforms--through movement of ground reaction forces and leg joints--during the stance period of gait. Able-bodied humans regulate effective shapes to be invariant across conditions such as heel height, walking speed, and body weight, so this measure has proven to be a very useful tool for the alignment and design of passive prostheses. However, leg joints must be actively controlled to assume different effective shapes that are unique to tasks such as standing, walking, and stair climbing. Using our previous simulation studies as a starting point, we model and control the effective shape as a virtual kinematic constraint on the powered Vanderbilt prosthetic leg with a custom instrumented foot. An able-bodied subject used a by-pass adapter to walk on the controlled leg over ground and over a treadmill. These preliminary experiments demonstrate, for the first time, that effective shape (or virtual constraints in general) can be used to control a powered prosthetic leg.

  1. Martensitic transformation, shape memory effects, and other curious mechanical effects

    International Nuclear Information System (INIS)

    Vandermeer, R.A.

    1982-01-01

    The objective of this paper is to review tutorially the subject of martensitic transformations in uranium alloys emphasizing their role in the shape memory effect (SME). We examine first what a martensitic transformation is, illustrating some of its characteristics with specific examples. As well as being athermal in nature, as expected, data are presented indicating that martensitic transformations in some uranium alloys also have a strong isothermal component. In addition, a few alloys are known to exhibit thermoelastic martensitic reactions. The SME, which is associated with these, is defined and demonstrated graphically with data from a uranium-6 wt % niobium alloy. Some of the important variables influencing SME behavior are described. Specifically, these are reheat temperature, amount of deformation, crystal structure, and composition. A mechanism for SME is postulated and the association with martensitic transformation is detailed. A self-induced shape instability in the uranium-7.5 wt % niobium-2.5 wt % zirconium alloy with a rationalization of the behavior in terms of texture and lattice parameter change during aging is reviewed and discussed. 24 figures

  2. Magnetocaloric effect in Heusler shape-memory alloys

    International Nuclear Information System (INIS)

    Planes, A.; Manosa, Ll.; Moya, X.; Krenke, T.; Acet, M.; Wassermann, E.F.

    2007-01-01

    We present a comparative study of the magnetocaloric properties of Ni-Mn-X Heusler shape-memory alloys with X=Ga, Sn and In. In these materials, the magnetocaloric effect is a consequence of the magnetostructural coupling that enables the magnetic shape-memory properties. We show that inverse magnetocaloric effects can occur in these materials. The origin of this anomalous behavior is different in stoichiometric Ni 2 MnGa and in Ni-Mn-Sn/In. In the former case it is related to the strong uniaxial magnetic anisotropy of the martensitic phase, while in the later it is an intrinsic effect associated with an incipient antiferromagnetism

  3. Shape-memory effect in Ti-Nb alloys

    International Nuclear Information System (INIS)

    Peradze, T.; Berikashvili, T.; Chelidze, T.; Gorgadze, K.; Bochorishvili, M.; Taktakishvili, M.

    2009-01-01

    The work deals with the investigation of the binary alloy of titanium with niobium and is aimed at demonstrating the functional-mechanical possibilities of Ti-Nb alloys from the viewpoint of their potential application in practice. The shape-memory effect, super elasticity and reactive stress in alloys of Ti-Nb system were studied. It turned out that the work carried out expanded the interval of Nb content in the investigated alloys from 25.9 to 33.1 wt%. The shape recovery made up not less than 90% at the deformation of 6-8%. The reactive stress reached 350-450 MPa. In the alloys under study another (high-temperature) shape-memory effect was found, and the influence of hydrogen and oxygen on the inelastic properties of alloys was studied. (author)

  4. Neutron irradiation effect on thermomechanical properties of shape memory alloys

    International Nuclear Information System (INIS)

    Abramov, V.Ya.; Ionajtis, R.R.; Kotov, V.V.; Loguntsev, E.N.; Ushakov, V.P.

    1996-01-01

    Alloys of Ti-Ni, Ti-Ni-Pd, Fe-Mn-Si, Mn-Cu-Cr, Mn-Cu, Cu-Al-Mn, Cu-Al-Ni systems are investigated after irradiation in IVV-2M reactor at various temperatures with neutron fluence of 10 19 - 10 20 cm -2 . The degradation of shape memory effect in titanium nickelide base alloys is revealed after irradiation. Mn-Cu and Mn-Cu-Cr alloys show the best results. Trends in shape memory alloy behaviour depending on irradiation temperature are found. A consideration is given to the possibility of using these alloys for components of power reactor control and protection systems [ru

  5. Shape memory effects in a uranium + 14 at. % niobium alloy

    International Nuclear Information System (INIS)

    Vandermeer, R.A.; Ogle, J.C.; Snyder, W.B. Jr.

    1978-01-01

    There is a class of alloys that, on cooling from elevated temperatures, experience a martensitic phase change. Some of these, when stressed in the martensitic state to an apparently plastic strain, recover their predeformed shape simply by heating. This striking shape recovery is known as the ''shape memory effect'' (SME). Up to a certain limiting strain, epsilon/sub L/, 100% shape recovery may be accomplished. This memory phenomenon seems to be attributable to the thermoelastic nature of and deformational modes associated with the phase transformation in the alloy. Thus, shape recovery results when a stress-biased martensite undergoes a heat-activated reversion back to the parent phase from which it originated. There are uranium alloys that demonstrate SME-behavior. Uranium-rich, uranium--niobium alloys were the first to be documented; New experimental observations of SME in a polycrystalline uranium--niobium alloy are presented. This alloy can exhibit a two-way memory under cetain circumstances. Additional indirect evidence is presented suggesting that the characteristics of the accompanying phase transformation in this alloy meet the criteria or ''selection rules'' deemed essential for SME

  6. Effects of Plasma Shaping on Nonlinear Gyrokinetic Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Belli, E. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Hammett, G. W. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Dorland, W. [Univ. of Maryland, College Park, MD (United States)

    2008-08-01

    The effects of flux surface shape on the gyrokinetic stability and transport of tokamak plasmas are studied using the GS2 code [M. Kotschenreuther, G. Rewoldt, and W.M. Tang, Comput. Phys. Commun. 88, 128 (1995); W. Dorland, F. Jenko, M. Kotschenreuther, and B.N. Rogers, Phys. Rev. Lett. 85, 5579 (2000)]. Studies of the scaling of nonlinear turbulence with shaping parameters are performed using analytic equilibria based on interpolations of representative shapes of the Joint European Torus (JET) [P.H. Rebut and B.E. Keen, Fusion Technol. 11, 13 (1987)]. High shaping is found to be a stabilizing influence on both the linear ion-temperature-gradient (ITG) instability and the nonlinear ITG turbulence. For the parameter regime studied here, a scaling of the heat flux with elongation of χ ~ κ-1.5 or κ-2.0, depending on the triangularity, is observed at fixed average temperature gradient. While this is not as strong as empirical elongation scalings, it is also found that high shaping results in a larger Dimits upshift of the nonlinear critical temperature gradient due to an enhancement of the Rosenbluth-Hinton residual zonal flows.

  7. Effects of Plasma Shaping on Nonlinear Gyrokinetic Turbulence

    International Nuclear Information System (INIS)

    E.A. Belli, G.W. Hammett and W. Dorland

    2008-01-01

    The effects of flux surface shape on the gyrokinetic stability and transport of tokamak plasmas are studied using the GS2 code [M. Kotschenreuther, G. Rewoldt, and W.M. Tang, Comput. Phys. Commun. 88, 128 (1995); W. Dorland, F. Jenko, M. Kotschenreuther, and B.N. Rogers, Phys. Rev. Lett. 85, 5579 (2000)]. Studies of the scaling of nonlinear turbulence with shaping parameters are performed using analytic equilibria based on interpolations of representative shapes of the Joint European Torus (JET) [P.H. Rebut and B.E. Keen, Fusion Technol. 11, 13 (1987)]. High shaping is found to be a stabilizing influence on both the linear ion-temperature-gradient (ITG) instability and the nonlinear ITG turbulence. For the parameter regime studied here, a scaling of the heat flux with elongation of χ ∼ κ -1.5 or κ -2.0 , depending on the triangularity, is observed at fixed average temperature gradient. While this is not as strong as empirical elongation scalings, it is also found that high shaping results in a larger Dimits upshift of the nonlinear critical temperature gradient due to an enhancement of the Rosenbluth-Hinton residual zonal flows

  8. Magnetic shape memory effect and highly mobile twin boundaries

    Czech Academy of Sciences Publication Activity Database

    Heczko, Oleg

    2014-01-01

    Roč. 30, č. 13 (2014), s. 1559-1578 ISSN 0267-0836 R&D Projects: GA ČR(CZ) GAP107/11/0391 Institutional support: RVO:68378271 Keywords : magnetic shape memory effect * ferromagnetic martensite * twinning * magnetically induced reorientation * reviews Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.995, year: 2014 http://dx.doi.org/10.1179/1743284714Y.0000000599

  9. Size, Shape and Impurity Effects on Superconducting critical temperature.

    Science.gov (United States)

    Umeda, Masaki; Kato, Masaru; Sato, Osamu

    Bulk superconductors have their own critical temperatures Tc. However, for a nano-structured superconductor, Tc depends on size and shape of the superconductor. Nishizaki showed that the high pressure torsion on bulks of Nb makes Tc higher, because the torsion makes many nano-sized fine grains in the bulks. However the high pressure torsion on bulks of V makes Tc lower, and Nishizaki discussed that the decrease of Tc is caused by impurities in the bulks of V. We studied size, shape, and impurity effects on Tc, by solving the Gor'kov equations, using the finite element method. We found that smaller and narrower superconductors show higher Tc. We found how size and shape affects Tc by studying spacial order parameter distributions and quasi-particle eigen-energies. Also we studied the impurity effects on Tc, and found that Tc decreases with increase of scattering rate by impurities. This work was supported in part of KAKENHI Grant Number JP26400367 and JP16K05460, and program for leading graduate schools of ministry of education, culture, sports, science and technology-Japan.

  10. Plasma shaping effects on tokamak scrape-off layer turbulence

    Science.gov (United States)

    Riva, Fabio; Lanti, Emmanuel; Jolliet, Sébastien; Ricci, Paolo

    2017-03-01

    The impact of plasma shaping on tokamak scrape-off layer (SOL) turbulence is investigated. The drift-reduced Braginskii equations are written for arbitrary magnetic geometries, and an analytical equilibrium model is used to introduce the dependence of turbulence equations on tokamak inverse aspect ratio (ε ), Shafranov’s shift (Δ), elongation (κ), and triangularity (δ). A linear study of plasma shaping effects on the growth rate of resistive ballooning modes (RBMs) and resistive drift waves (RDWs) reveals that RBMs are strongly stabilized by elongation and negative triangularity, while RDWs are only slightly stabilized in non-circular magnetic geometries. Assuming that the linear instabilities saturate due to nonlinear local flattening of the plasma gradient, the equilibrium gradient pressure length {L}p=-{p}e/{{\

  11. Effect of electrode shape on grounding resistances - Part 2

    DEFF Research Database (Denmark)

    Tomaskovicova, Sonia; Ingeman-Nielsen, Thomas; Christiansen, Anders V.

    2016-01-01

    Although electric resistivity tomography (ERT) is now regarded as a standard tool in permafrost monitoring, high grounding resistances continue to limit the acquisition of time series over complete freeze-thaw cycles. In an attempt to alleviate the grounding resistance problem, we have tested three...... electrode designs featuring increasing sizes and surface area, in the laboratory and at three different field sites in Greenland. Grounding resistance measurements showed that changing the electrode shape (using plates instead of rods) reduced the grounding resistances at all sites by 28%-69% during...... unfrozen and frozen ground conditions. Using meshes instead of plates (the same rectangular shape and a larger effective surface area) further improved the grounding resistances by 29%-37% in winter. Replacement of rod electrodes of one entire permanent permafrost monitoring array by meshes resulted...

  12. Neutron flux shape effects in large fast reactor safety calculations

    International Nuclear Information System (INIS)

    Galati, A.; Loizzo, P.; Musco, A.

    1978-01-01

    Three classes of accidents in a large fast reactor were studied by the two-dimensional core dynamics code NADYP-2. A Modified version of the code, including a point kinetics module, allowed comparison between 2D and 0D power, reactivity and temperature histories. A strong shape effect was evidenced by these calculations in the boiling phase of LOF accidents as well as in the accident generated by control rod removal. Some future possibilities of by passing the consequences of this effect are indicated

  13. Effect of wire shape on wire array discharge

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M. [University of Tokushima, Department of Electrical and Electronic Engineering, Tokushima (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto University, Department of Electrical and Computer Engineering, Kumamoto (Japan)

    2001-09-01

    Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

  14. Effect of wire shape on wire array discharge

    International Nuclear Information System (INIS)

    Shimomura, N.; Tanaka, Y.; Yushita, Y.; Nagata, M.; Teramoto, Y.; Katsuki, S.; Akiyama, H.

    2001-01-01

    Although considerable investigations have been reported on z-pinches to achieve nuclear fusion, little attention has been given from the point of view of how a wire array consisting of many parallel wires explodes. Instability existing in the wire array discharge has been shown. In this paper, the effect of wire shape in the wire array on unstable behavior of the wire array discharge is represented by numerical analysis. The claws on the wire formed in installation of wire may cause uniform current distribution on wire array. The effect of error of wire diameter in production is computed by Monte Carlo Method. (author)

  15. False consensus effect for attitudes related to body shape in normal weight women concerned with body shape.

    Science.gov (United States)

    Muller, S L; Williamson, D A; Martin, C K

    2002-06-01

    This study investigated the presence of the False Consensus Effect (FCE) with body and shape-related attitudes in 30 normal weight women who scored high or low on a measure of concern with body shape. The participants were asked to rate depressive, positive, neutral, and body shape self-statements for relevance to self and to others. They also estimated the percentage of individuals that would agree with each attitudinal statement. Women with high body shape concerns rated themselves and others as significantly more likely to agree with the statements expressing such concerns than those with low concerns. They also believed that a significantly higher percentage of others would favor those attitudes. This pattern of findings is supportive of the presence of a FCE in normal weight women preoccupied with body shape and size.

  16. The Effects of Different Electrode Types for Obtaining Surface Machining Shape on Shape Memory Alloy Using Electrochemical Machining

    Science.gov (United States)

    Choi, S. G.; Kim, S. H.; Choi, W. K.; Moon, G. C.; Lee, E. S.

    2017-06-01

    Shape memory alloy (SMA) is important material used for the medicine and aerospace industry due to its characteristics called the shape memory effect, which involves the recovery of deformed alloy to its original state through the application of temperature or stress. Consumers in modern society demand stability in parts. Electrochemical machining is one of the methods for obtained these stabilities in parts requirements. These parts of shape memory alloy require fine patterns in some applications. In order to machine a fine pattern, the electrochemical machining method is suitable. For precision electrochemical machining using different shape electrodes, the current density should be controlled precisely. And electrode shape is required for precise electrochemical machining. It is possible to obtain precise square holes on the SMA if the insulation layer controlled the unnecessary current between electrode and workpiece. If it is adjusting the unnecessary current to obtain the desired shape, it will be a great contribution to the medical industry and the aerospace industry. It is possible to process a desired shape to the shape memory alloy by micro controlling the unnecessary current. In case of the square electrode without insulation layer, it derives inexact square holes due to the unnecessary current. The results using the insulated electrode in only side show precise square holes. The removal rate improved in case of insulated electrode than others because insulation layer concentrate the applied current to the machining zone.

  17. Studies of Standard Heat Treatment Effects on Microstructure and Mechanical Properties of Laser Net Shape Manufactured INCONEL 718

    Science.gov (United States)

    Qi, H.; Azer, M.; Ritter, A.

    2009-10-01

    Laser net shape manufacturing (LNSM) is a laser cladding/deposition based technology, which can fabricate and repair near-net-shape high-performance components directly from metal powders. Characterizing mechanical properties of the laser net shape manufactured components is prerequisite to the applications of LNSM in aircraft engine industrial productions. Nickel-based superalloys such as INCONEL 718 are the most commonly used metal materials in aircraft engine high-performance components. In this study, the laser deposition process is optimized through a set of designed experiments to reduce the porosity to less than 0.03 pct. It is found that the use of plasma rotating electrode processed (PREP) powder and a high energy input level greater than 80 J/mm are necessary conditions to minimize the porosity. Material microstructure and tensile properties of laser-deposited INCONEL 718 are studied and compared under heat treatment conditions of as deposited, direct aged, solution treatment and aging (STA), and full homogenization followed by STA. Tensile test results showed that the direct age heat treatment produces the highest tensile strength equivalent to the wrought material, which is followed by the STA-treated and the homogenization-treated tensile strengths, while the ductility exhibits the reverse trend. Finally, failure modes of the tensile specimens were analyzed with fractography.

  18. Effect of stern hull shape on turning circle of ships

    Science.gov (United States)

    Jaswar, Maimun, A.; Wahid, M. A.; Priyanto, A.; Zamani, Pauzi, Saman

    2012-06-01

    Many factors such as: stern hull shape, length, draught, trim, propulsion system and external forces affecting the drift angle influence rate of turn and size of turning circle of ships. This paper discusses turning circle characteristics of U and V stern hull shape of Very Large Crude Oil Carrier (VLCC) ships. The ships have same principal dimension such as length, beam, and draught. The turning circle characteristics of the VLCC ships are simulated at 35 degree of rudder angle. In the analysis, firstly, turning circle performance of U-type VLCC ship is simulated. In the simulation, initial ship speed is determined using given power and rpm. Hydrodynamic derivatives coefficients are determined by including effect of fullness of aft run. Using the obtained, speed and hydrodynamic coefficients, force and moment acting on hull, force and moment induced by propeller, force and moment induced by rudder are determined. Finally, ship trajectory, ratio of speed, yaw angle and drift angle are determined. Results of simulation results of the VLCC ship are compared with the experimental one as validation. Using the same method, V-type VLCC is simulated and the simulation results are compared with U-type VLCC ship. Results shows the turning circle of U-type is larger than V-type due to effect stern hul results of simulation are.

  19. Pb nanoprecipitates in Al: Magic-shape effects due to elastic strain

    DEFF Research Database (Denmark)

    Hamilton, J.C.; Leoard, F.; Johnson, Erik

    2007-01-01

    We present a theory for size-dependent shapes of Pb nanoprecipitates in Al, introducing the concept of "magic shapes," i.e., shapes having near-zero homogeneous elastic strains. Our quantitative atomistic calculations of edge energies show their effect on precipitate shape to be negligible, thus...

  20. Shape Memory Effect Actuators from Chlorides, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Shape Change Technologies is developing a radical new technique for the fabrication of Shape Memory alloys, such as TiNi and its ternary alloys of Hf, Zr, and Cu....

  1. Factors influencing shape memory effect and phase transformation behaviour of Fe-Mn-Si based shape memory alloys

    International Nuclear Information System (INIS)

    Li, H.; Dunne, D.; Kennon, N.

    1999-01-01

    The objective of this research work was to investigate the factors influencing the shape memory effect and phase transformation behaviour of three Fe-Mn-Si based shape memory alloys: Fe-28Mn-6Si, Fe-13Mn-5Si-10Cr-6Ni and Fe-20Mn-6Si-7Cr-1Cu. The research results show that the shape memory capacity of Fe-Mn-Si based shape memory alloys varies with annealing temperature, and this effect can be explained in terms of the effect of annealing on γ ε transformation. The nature and concentration of defects in austenite are strongly affected by annealing conditions. A high annealing temperature results in a low density of stacking faults, leading to a low nucleation rate during stress induced γ→ε transformation. The growth of ε martensite plates is favoured rather than the formation of new ε martensite plates. Coarse martensite plates produce high local transformation strains which can be accommodated by local slip deformation, leading to a reduction in the reversibility of the martensitic transformation and to a degradation of the shape memory effect. Annealing at low temperatures (≤673 K) for reasonable times does not eliminate complex defects (dislocation jogs, kinks and vacancy clusters) created by hot and cold working strains. These defects can retard the movement and rearrangement of Shockley partial dislocations, i.e. suppress γ→ε transformation, also leading to a degradation of shape memory effect. Annealing at about 873 K was found to be optimal to form the dislocation structures which are favourable for stress induced martensitic transformation, thus resulting in the best shape memory behaviour. (orig.)

  2. Fast-Response-Time Shape-Memory-Effect Foam Actuators

    Science.gov (United States)

    Jardine, Peter

    2010-01-01

    Bulk shape memory alloys, such as Nitinol or CuAlZn, display strong recovery forces undergoing a phase transformation after being strained in their martensitic state. These recovery forces are used for actuation. As the phase transformation is thermally driven, the response time of the actuation can be slow, as the heat must be passively inserted or removed from the alloy. Shape memory alloy TiNi torque tubes have been investigated for at least 20 years and have demonstrated high actuation forces [3,000 in.-lb (approximately equal to 340 N-m) torques] and are very lightweight. However, they are not easy to attach to existing structures. Adhesives will fail in shear at low-torque loads and the TiNi is not weldable, so that mechanical crimp fits have been generally used. These are not reliable, especially in vibratory environments. The TiNi is also slow to heat up, as it can only be heated indirectly using heater and cooling must be done passively. This has restricted their use to on-off actuators where cycle times of approximately one minute is acceptable. Self-propagating high-temperature synthesis (SHS) has been used in the past to make porous TiNi metal foams. Shape Change Technologies has been able to train SHS derived TiNi to exhibit the shape memory effect. As it is an open-celled material, fast response times were observed when the material was heated using hot and cold fluids. A methodology was developed to make the open-celled porous TiNi foams as a tube with integrated hexagonal ends, which then becomes a torsional actuator with fast response times. Under processing developed independently, researchers were able to verify torques of 84 in.-lb (approximately equal to 9.5 Nm) using an actuator weighing 1.3 oz (approximately equal to 37 g) with very fast (less than 1/16th of a second) initial response times when hot and cold fluids were used to facilitate heat transfer. Integrated structural connections were added as part of the net shape process, eliminating

  3. Shape Effect on the Temperature Field during Microwave Heating Process

    Directory of Open Access Journals (Sweden)

    Zhijun Zhang

    2018-01-01

    Full Text Available Aiming at improving the food quality during microwave process, this article mainly focused on the numerical simulation of shape effect, which was evaluated by microwave power absorption capability and temperature distribution uniformity in a single sample heated in a domestic microwave oven. This article only took the electromagnetic field and heat conduction in solid into consideration. The Maxwell equations were used to calculate the distribution of microwave electromagnetic field distribution in the microwave cavity and samples; then the electromagnetic energy was coupled as the heat source in the heat conduction process in samples. Quantitatively, the power absorption capability and temperature distribution uniformity were, respectively, described by power absorption efficiency (PAE and the statistical variation of coefficient (COV. In addition, we defined the comprehensive evaluation coefficient (CEC to describe the usability of a specific sample. In accordance with volume or the wave numbers and penetration numbers in the radial and axial directions of samples, they can be classified into different groups. And according to the PAE, COV, and CEC value and the specific need of microwave process, an optimal sample shape and orientation could be decided.

  4. Shape memory effects, thermal expansion and B19' martensite texture in titanium nickelide

    International Nuclear Information System (INIS)

    Zel'dovich, V.I.; Sobyanina, G.A.; Rinkevich, O.S.; Gundyrev, V.M.

    1996-01-01

    The influence of plastic deformation by tension and cold rolling on shape memory effect, reverse shape memory effect, thermal expansion and texture state of martensite in titanium nickelide is under study. The relationship of thermal expansion coefficient to the value of strain during direct and reverse shape memory effect is established

  5. The effect of particle shape on hopper discharge

    Energy Technology Data Exchange (ETDEWEB)

    Cleary, P.W. [CSIRO, Clayton, Vic. (Australia). Mathematical and Information Sciences

    1999-07-01

    Hopper flows are an important class of industrial particle flows. The inclusion of particle shape allows DEM models to replicate many features of real hopper flows that are not possible when using circular particles. Elongated particles can produce flow rates up to 30% lower than for circular particles and the flow patterns are quite different. The yielding of the particle microstructure resembles more the tearing of a continuum solid, with large scale quasi-stable voids being formed and large groups of particles moving together. The flow becomes increasingly concentrated in a relatively narrow funnel above the hopper opening. This is encouragement that DEM may be able to predict important problems such as bridging and rat-holing. Increasing the blockiness or angularity of the particles also increases resistance to flow and reduces flow rates by up to 28% but does not have any perceptible effect on the nature of the flow. 11 refs., 7 figs.

  6. Martensitic transformations and the shape memory effect in Ti-Zr-Nb-Al high-temperature shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fei; Yu, Zhiguo; Xiong, Chengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Qu, Wentao; Yuan, Bifei [School of Mechanical Engineering, Xi’an Shiyou University, Xi’an 710065 (China); Wang, Zhenguo [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China)

    2017-01-02

    The microstructures, phase transformations, mechanical properties and shape memory effect of Ti-20Zr-10Nb-xAl (x=1, 2, 3, 4 at%) alloys were investigated. The X-ray diffraction results show that the alloys are composed of a single martensitic α″-phase and that the corresponding unit cell volume decreases with increasing Al content. The reverse martensitic transformation start temperature (A{sub s}) of the Ti-20Zr-10Nb-Al alloy is 534 K and decreases with increasing Al content. The addition of Al results in solid solution strengthening and grain refinement strengthening, thus improving the mechanical properties and the shape memory effect of the Ti-20Zr-10 Nb-xAl alloys. The Ti-20Zr-10Nb-3Al alloy shows the greatest shape memory strain (3.2%) and the largest tensile strain (17.6%) as well as a very high tensile strength (886 MPa).

  7. Shape Effects in Nanoparticle-Based Imaging Agents

    Science.gov (United States)

    Culver, Kayla Shani Brook

    to characterize complex nanoscale structural features and spectral properties of gold nanostars. Specifically, by evaluating the DIC contrast and image patterns of single nanostars, I distinguished between flat and 3D geometries, identified nanostars with 4-fold symmetry, and determined nanostar orientation. Additionally, in multi-wavelength DIC imaging, an inversion in the contrast could be used to indicate the localized surface plasmon resonance of nanostars with 1 and 2 branches. Next, I used DIC to track the rotational and translational dynamics of functionalized nanostars interacting with live cell membranes. The DNA aptamer ligand on the nanostars specifically targets the transmembrane receptor HER2. I tracked single nanoconstructs over long time scales (˜ 20 minutes per particle, > 80 minutes total) with high temporal resolution (4 fps) and found that analysis of the DIC contrast fluctuations could be used to identify multiple modes of rotational behavior on the cell membrane. I developed MATLAB programs to track the moving nanoconstructs in a dynamic background environment and set up a customized live-cell perfusion chamber that is compatible with the bulky high numerical aperture optics. The combination of the environmental control in the chamber and the low light levels required to visualize single nanostars make this technique optimal for long-term tracking of single nanoconstructs in viable cells. Although nanoparticle size is well-known to influence the relaxivity of Gd(III)-based MRI contrast agents that are attached to the surface, the role of nanoparticle shape was previously unknown. Recently, we discovered that the relaxivity of Gd(III)-conjugated DNA bound to nanostars was three-fold higher than that of analogous spherical nanoconstructs. The relaxivities reached enhancements that were beyond limits that could be explained theoretically by size effects alone. We found that the extremely large enhancements could be explained by elongated water

  8. RE-Shaping. Shaping an effective and efficient European renewable energy market. D23 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Rathmann, M.; Klessmann, C.; Nabe, C.; De Jager, D.; De Lovinfosse, I. [Ecofys, Utrecht (Netherlands); Ragwitz, M.; Steinhilber, S.; Breitschopf, B. [Fraunhofer Institute for Systems and Innovation Research ISI, Karlsruhe (Germany); Burgers, J.; Boots, M. [KEMA, Arnhem (Netherlands); Weoeres, B. [EnergoBanking, Budapest (Hungary); Resch, G.; Panzer, C.; Ortner, A.; Busch, S. [Vienna University of Technology, Institute of Energy Systems and Electric Drives, Energy Economics Group EEG, Vienna (Austria); Neuhoff, K.; Boyd, R. [Climate Policy Initiative, German Institute for Economic Research (DIW Berlin), Berlin (Germany); Junginger, M.; Hoefnagels, R. [Utrecht University, Utrecht (Netherlands); Cusumano, N.; Lorenzoni, A. [Bocconi University, Milan (Italy); Konstantinaviciute, I. [Lithuanian Energy Institute LEI, Kaunas (Lithuania)

    2012-02-15

    The core objective of the RE-Shaping project is to assist Member State governments in preparing for the implementation of Directive 2009/28/EC (on the promotion of the use of energy from renewable sources) and to guide a European policy for RES (renewable energy sources) in the mid- to long term. The past and present success of policies for renewable energies will be evaluated and recommendations derived to improve future RES support schemes. The core content of this collaborative research activity comprises: Developing a comprehensive policy background for RES support instruments; Providing the European Commission and Member States with scientifically based and statistically robust indicators to measure the success of currently implemented RES policies; Proposing innovative financing schemes for lower costs and better capital availability in RES financing; Initiation of National Policy Processes which attempt to stimulate debate and offer key stakeholders a meeting place to set and implement RES targets as well as options to improve the national policies fostering RES market penetration; Assessing options to coordinate or even gradually harmonize national RES policy approaches. This report marks the end of the research project RE-Shaping and summarizes its research activities, results, and recommendations.

  9. Nickel powders shape effect upon their isostatic compaction behavior

    International Nuclear Information System (INIS)

    Cytermann, R.; Auguin, B.; Defresne, A.; Gilles, P.

    1975-01-01

    Two carbonyl nickel powders of the same purity, one spherical, the other of very irregular shape, were isostatically compacted at pressures from 0.5 to 13Kbars with two compacting speeds: 1Kbar/s and 1Kbar/15s. The influence of the powder shapes on the electrical resistivity, tensile strength and microcalorimetric measurements was studied [fr

  10. The QWERTY effect: how typing shapes the meanings of words.

    Science.gov (United States)

    Jasmin, Kyle; Casasanto, Daniel

    2012-06-01

    The QWERTY keyboard mediates communication for millions of language users. Here, we investigated whether differences in the way words are typed correspond to differences in their meanings. Some words are spelled with more letters on the right side of the keyboard and others with more letters on the left. In three experiments, we tested whether asymmetries in the way people interact with keys on the right and left of the keyboard influence their evaluations of the emotional valence of the words. We found the predicted relationship between emotional valence and QWERTY key position across three languages (English, Spanish, and Dutch). Words with more right-side letters were rated as more positive in valence, on average, than words with more left-side letters: the QWERTY effect. This effect was strongest in new words coined after QWERTY was invented and was also found in pseudowords. Although these data are correlational, the discovery of a similar pattern across languages, which was strongest in neologisms, suggests that the QWERTY keyboard is shaping the meanings of words as people filter language through their fingers. Widespread typing introduces a new mechanism by which semantic changes in language can arise.

  11. Universality for shape dependence of Casimir effects from Weyl anomaly

    Science.gov (United States)

    Miao, Rong-Xin; Chu, Chong-Sun

    2018-03-01

    We reveal elegant relations between the shape dependence of the Casimir effects and Weyl anomaly in boundary conformal field theories (BCFT). We show that for any BCFT which has a description in terms of an effective action, the near boundary divergent behavior of the renormalized stress tensor is completely determined by the central charges of the theory. These relations are verified by free BCFTs. We also test them with holographic models of BCFT and find exact agreement. We propose that these relations between Casimir coefficients and central charges hold for any BCFT. With the holographic models, we reproduce not only the precise form of the near boundary divergent behavior of the stress tensor, but also the surface counter term that is needed to make the total energy finite. As they are proportional to the central charges, the near boundary divergence of the stress tensor must be physical and cannot be dropped by further artificial renormalization. Our results thus provide affirmative support on the physical nature of the divergent energy density near the boundary, whose reality has been a long-standing controversy in the literature.

  12. Fin field effect transistor directionality impacts printing of implantation shapes

    Science.gov (United States)

    Wang, Xiren; Granik, Yuri

    2018-01-01

    In modern integrated circuit (IC) fabrication processes, the photoresist receives considerable illumination energy that is reflected by underlying topography during optical lithography of implantation layers. Bottom antireflective coating (BARC) is helpful to mitigate the reflection. Often, however, BARC is not used, because its removal is technically challenging, in addition to its relatively high economic cost. Furthermore, the advanced technology nodes, such as 14/10-nm nodes, have introduced fin field effect transistor (FinFET), which makes reflection from nonuniform silicon substrates exceptionally complicated. Therefore, modeling reflection from topography becomes obligatory to accurately predict printing of implantation shapes. Typically, FinFET is always fixed in one direction in realistic designs. However, the same implantation rectangle may be oriented in either horizontal or vertical direction. Then, there are two types of relations between the critical dimension (CD) and FinFET, namely a parallel-to and a perpendicular-to relation. We examine the fin directionality impact on CD. We found that this impact may be considerable in some cases. We use our in-house rigorous optical topography simulator to reveal underlining physical reasons. One of the major causes of the CD differences is that in the parallel orientation, the solid sidewalls of the fins conduct considerable light reflections unlike for the perpendicular orientation. This finding can aid the compact modeling in optical proximity correction of implantation masks.

  13. Effect of the Potential Shape on the Stochastic Resonance Processes

    Science.gov (United States)

    Kenmoé, G. Djuidjé; Ngouongo, Y. J. Wadop; Kofané, T. C.

    2015-10-01

    The stochastic resonance (SR) induced by periodic signal and white noises in a periodic nonsinusoidal potential is investigated. This phenomenon is studied as a function of the friction coefficient as well as the shape of the potential. It is done through an investigation of the hysteresis loop area which is equivalent to the input energy lost by the system to the environment per period of the external force. SR is evident in some range of the shape parameter of the potential, but cannot be observed in the other range. Specially, variation of the shape potential affects significantly and not trivially the heigh of the potential barrier in the Kramers rate as well as the occurrence of SR. The finding results show crucial dependence of the temperature of occurrence of SR on the shape of the potential. It is noted that the maximum of the input energy generally decreases when the friction coefficient is increased.

  14. Brand visualization: Effects of "product shape- typeface design" congruence on brand perceptions and price expectations

    NARCIS (Netherlands)

    van Rompay, Thomas Johannes Lucas; Pruyn, Adriaan T.H.

    2008-01-01

    This research addresses effects of congruence of symbolic meanings connoted through product shape and typeface design on brand perceptions and price expectations. Based on processing fluency accounts, it is predicted that shape-typeface congruence, as opposed to shape-typeface incongruence,

  15. EFFECTS OF FORSTERITE GRAIN SHAPE ON INFRARED SPECTRA

    International Nuclear Information System (INIS)

    Koike, C.; Imai, Y.; Chihara, H.; Murata, K.; Tsuchiyama, A.; Suto, H.; Tachibana, S.; Ohara, S.

    2010-01-01

    The Infrared Space Observatory (ISO) detected several sharp infrared features around young stars, comets, and evolved stars. These sharp features were identified as Mg-rich crystalline silicates of forsterite and enstatite by comparison with spectra from laboratory data. However, certain infrared emission bands in the observed spectra cannot be identified because they appear at slightly shorter wavelengths than the peaks in forsterite laboratory spectra, where the shapes of forsterite particles are irregular. To solve this problem, we measured infrared spectra of forsterite grains of various shapes (irregular, plate-like with no sharp edges, elliptical, cauliflower, and spherical) in the infrared spectral region between 5 and 100 μm. The spectra depend on particle shape. The spectra of the 11, 19, 23, and 33 μm bands, in particular, are extremely sensitive to particle shape, whereas some peaks such as the 11.9, 49, and 69 μm bands remained almost unchanged despite different particle shapes. This becomes most evident from the spectra of near-spherical particles produced by annealing an originally amorphous silicate sample at temperature from 600 to 1150 deg. C. The spectra of these samples differ strongly from those of other ones, showing peaks at much shorter wavelengths. At a higher annealing temperature of 1200 deg. C, the particle shapes changed drastically from spherical to irregular and the spectra became similar to those of forsterite particles with irregular shapes. Based on ISO data and other observational data, the spectra of outflow sources and disk sources may correspond to differences in forsterite shape, and further some unidentified peaks, such as those at 32.8 or 32.5 μm, may be due to spherical or spherical-like forsterite.

  16. Effects of object shape on the visual guidance of action.

    Science.gov (United States)

    Eloka, Owino; Franz, Volker H

    2011-04-22

    Little is known of how visual coding of the shape of an object affects grasping movements. We addressed this issue by investigating the influence of shape perturbations on grasping. Twenty-six participants grasped a disc or a bar that were chosen such that they could in principle be grasped with identical movements (i.e., relevant sizes were identical such that the final grips consisted of identical separations of the fingers and no parts of the objects constituted obstacles for the movement). Nevertheless, participants took object shape into account and grasped the bar with a larger maximum grip aperture and a different hand angle than the disc. In 20% of the trials, the object changed its shape from bar to disc or vice versa early or late during the movement. If there was enough time (early perturbations), grasps were often adapted in flight to the new shape. These results show that the motor system takes into account even small and seemingly irrelevant changes of object shape and adapts the movement in a fine-grained manner. Although this adaptation might seem computationally expensive, we presume that its benefits (e.g., a more comfortable and more accurate movement) outweigh the costs. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Effect of adding Si on shape memory effect in Co-Ni alloy system

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Weimin [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China); Liu Yan [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Jiang Bohong [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)]. E-mail: bhjiang@sjtu.edu.cn; Zhou Pingnan [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2006-11-25

    In this paper, the effect of adding Si to Co-31.5 mass% Ni alloys on fcc-hcp martensitic transformation is investigated. The Co-Ni-Si ternary alloys with different amount of Si from 1 to 5 mass% were prepared. The stacking fault probability of Co-Ni-Si polycrystalline alloys were determined by X-ray diffraction profile analysis and compared with the binary Co-Ni alloy. The results show that the stacking fault probability of the fcc phase of alloys increases with increasing Si content. The effect of Si on phase transformation and shape memory behavior is evaluated. The experimental results show that both the critical strength and the shape memory effect of the ternary alloys will increase by the addition of Si. The improvement mechanism of the shape memory effect by adding Si to binary Co-Ni alloys is discussed.

  18. The effects of floodplain soil heterogeneity on meander planform shape

    Science.gov (United States)

    Motta, D.; Abad, J. D.; Langendoen, E. J.; GarcíA, M. H.

    2012-09-01

    Past analytical studies of meander planform development have mostly focused on the complexity of the governing equations, i.e., hydrodynamics, and less so on the stream bank resistance to erosion, whose spatial heterogeneity is difficult to describe deterministically. This motivated the use of a Monte Carlo approach to examine the effects of floodplain soils and their distribution on planform development, with the goal of including bank erosion properties in the analysis. Simulated bank erosion rates are controlled by the resistance to hydraulic erosion of the bank soils using an excess shear stress approach. The spatial distribution of critical shear stress across the floodplain is delineated on a rectangular, equidistant grid with varying degrees of variability. The corresponding erodibility coefficient is computed using a field-derived empirical relation. For a randomly disturbed distribution, in which the mean resistance to erosion exponentially increases away from the valley centerline, two relevant parameters are identified: the standard deviation of the critical shear stress distribution, which controls skewness and variability of the channel centerline, and the cross-valley increase in soil resistance, which constrains lateral migration and also affects bend skewness. For a purely random distribution, migrated centerlines exhibit larger variability for increasing spatial scales of floodplain soil heterogeneity. For equal stochastic variability of the corresponding governing parameters, relating meander migration to hydraulic erosion of the bank soils produces more variability and shape complexity than the "classic" bank migration approach of Ikeda et al. (1981), which relates migration rate to excess velocity at the outer bank. Finally, the proposed stochastic approach provides a foundation for estimating a suitable spatial density of measurements to characterize the physical properties of floodplain soils and vegetation.

  19. Effective thermo-mechanical properties and shape memory effect of CNT/SMP composites

    Science.gov (United States)

    Yang, Qingsheng; Liu, Xia; Leng, Fangfang

    2009-07-01

    Shape memory polymer (SMP) has been applied in many fields as intelligent sensors and actuators. In order to improve the mechanical properties and recovery force of SMP, the addition of minor amounts of carbon nanotubes (CNT) into SMP has attracted wide attention. A micromechanical model and thermo-mechanical properties of CNT/SMP composites were studied in this paper. The thermo-mechanical constitutive relation of intellectual composites with isotropic and transversely isotropic CNT was obtained. Moreover, the shape memory effect of CNT/SMP composites and the effect of temperature and the volume fraction of CNT were discussed. The work shows that CNT/SMP composites exhibit excellent macroscopic thermo-mechanical properties and shape memory effect, while both of them can be affected remarkably by temperature and the microstructure parameters.

  20. Dome-shaped PDC cutters drill harder rock effectively

    International Nuclear Information System (INIS)

    Moran, D.P.

    1992-01-01

    This paper reports that rock mechanics and sonic travel time log data indicate that bits with convex-shaped polycrystalline diamond compact (PDC) cutters can drill harder rock formations than comparable bits with flat PDC cutters. The Dome-shaped cutters have drilled carbonate formations with sonic travel times as small as 50 μsec/ft, compared to the standard cutoff of 75 μsec/ft for flat PCD cutters. Recent field data from slim hole wells drilled in the Permian basin have shown successful applications of the 3/8-in. Dome cutter in the Grayburg dolomite with its sonic travel times as low as 50-55 μsec/ft and compressive strengths significantly greater than the standard operating range for PDC bit applications. These field data indicate that the Dome cutters can successfully drill hard rock. The convex cutter shape as good impact resistance, cuttings removal, heat dissipation, and wear resistance

  1. Subharmonic emissions from microbubbles: effect of the driving pulse shape.

    Science.gov (United States)

    Biagi, Elena; Breschi, Luca; Vannacci, Enrico; Masotti, Leonardo

    2006-11-01

    The aims of this work are to investigate the response of the ultrasonic contrast agents (UCA) insonified by different arbitrary-shaped pulses at different acoustic pressures and concentration of the contrast agent focusing on subharmonic emission. A transmission setup was developed in order to insonify the contrast agent contained in a measurement chamber. The transmitted ultrasonic signals were generated by an arbitrary wave generator connected to a linear power amplifier able to drive a single-element transducer. The transmitted ultrasonic pulses that passed through the contrast agent-filled chamber were received by a second transducer or a hydrophone aligned with the first one. The radio frequency (RF) signals were acquired by fast echographic multiparameters multi-image novel apparatus (FEMMINA), which is an echographic platform able to acquire ultrasonic signals in a real-time modality. Three sets of ultrasonic signals were devised in order to evaluate subharmonic response of the contrast agent respect with sinusoidal burst signals used as reference pulses. A decreasing up to 30 dB in subharmonic response was detected for a Gaussian-shaped pulse; differences in subharmonic emission up to 21 dB were detected for a composite pulse (two-tone burst) for different acoustic pressures and concentrations. Results from this experimentation demonstrated that the transmitted pulse shape strongly affects subharmonic emission in spite of a second harmonic one. In particular, the smoothness of the initial portion of the shaped pulses can inhibit subharmonic generation from the contrast agents respect with a reference sinusoidal burst signal. It also was shown that subharmonic generation is influenced by the amplitude and the concentration of the contrast agent for each set of the shaped pulses. Subharmonic emissions that derive from a nonlinear mechanism involving nonlinear coupling among different oscillation modes are strongly affected by the shape of the ultrasonic

  2. Flux surface shaping effects on tokamak edge turbulence and flows

    International Nuclear Information System (INIS)

    Kendl, A.; Scott, B.D.

    2004-01-01

    The influence of shaping of magnetic flux surfaces in tokamaks on gyro-fluid edge turbulence is studied numerically. Magnetic field shaping in tokamaks is mainly due to elongation, triangularity, shift and the presence of a divertor X-point. A series of tokamak configurations with varying elongation 1 ≤ κ ≥ 2 and triangularity 0 ≤ δ ≤ 0.4, and an actual ASDEX Upgrade divertor configuration are obtained with the equilibrium code HELENA and implemented into the gyro-fluid turbulence code GEM. The study finds minimal impact on the zonal flow physics itself, but strong impact on the turbulence and transport. (authors)

  3. Flux surface shaping effects on tokamak edge turbulence and flows

    Energy Technology Data Exchange (ETDEWEB)

    Kendl, A. [Innsbruck Univ., Institut fuer Theoretische Physik, Association EURATOM (Austria); Scott, B.D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei Muenchen (Germany)

    2004-07-01

    The influence of shaping of magnetic flux surfaces in tokamaks on gyro-fluid edge turbulence is studied numerically. Magnetic field shaping in tokamaks is mainly due to elongation, triangularity, shift and the presence of a divertor X-point. A series of tokamak configurations with varying elongation 1 {<=} {kappa} {>=} 2 and triangularity 0 {<=} {delta} {<=} 0.4, and an actual ASDEX Upgrade divertor configuration are obtained with the equilibrium code HELENA and implemented into the gyro-fluid turbulence code GEM. The study finds minimal impact on the zonal flow physics itself, but strong impact on the turbulence and transport. (authors)

  4. Magnetic shape memory effect at 1.7 K

    Czech Academy of Sciences Publication Activity Database

    Heczko, Oleg; Kopecký, Vít; Sozinov, A.; Straka, L.

    2013-01-01

    Roč. 103, č. 7 (2013), "072405-1"-"072405-4" ISSN 0003-6951 R&D Projects: GA ČR(CZ) GAP107/11/0391 Institutional support: RVO:68378271 Keywords : shape memory alloys Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.515, year: 2013 http://dx.doi.org/10.1063/1.4817941

  5. Kirkwood-Buff integrals of finite systems: shape effects

    Science.gov (United States)

    Dawass, Noura; Krüger, Peter; Simon, Jean-Marc; Vlugt, Thijs J. H.

    2018-06-01

    The Kirkwood-Buff (KB) theory provides an important connection between microscopic density fluctuations in liquids and macroscopic properties. Recently, Krüger et al. derived equations for KB integrals for finite subvolumes embedded in a reservoir. Using molecular simulation of finite systems, KB integrals can be computed either from density fluctuations inside such subvolumes, or from integrals of radial distribution functions (RDFs). Here, based on the second approach, we establish a framework to compute KB integrals for subvolumes with arbitrary convex shapes. This requires a geometric function w(x) which depends on the shape of the subvolume, and the relative position inside the subvolume. We present a numerical method to compute w(x) based on Umbrella Sampling Monte Carlo (MC). We compute KB integrals of a liquid with a model RDF for subvolumes with different shapes. KB integrals approach the thermodynamic limit in the same way: for sufficiently large volumes, KB integrals are a linear function of area over volume, which is independent of the shape of the subvolume.

  6. Systematic description of the effect of particle shape on the strength properties of granular media

    Directory of Open Access Journals (Sweden)

    Azéma Emilien

    2017-01-01

    Full Text Available In this paper, we explore numerically the effect of particle shape on the mechanical behavior of sheared granular packings. In the framework of the Contact Dynamic (CDMethod, we model angular shape as irregular polyhedral particles, non-convex shape as regular aggregates of four overlapping spheres, elongated shape as rounded cap rectangles and platy shape as square-plates. Binary granular mixture consisting of disks and elongated particles are also considered. For each above situations, the number of face of polyhedral particles, the overlap of spheres, the aspect ratio of elongated and platy particles, are systematically varied from spheres to very angular, non-convex, elongated and platy shapes. The level of homogeneity of binary mixture varies from homogenous packing to fully segregated packings. Our numerical results suggest that the effects of shape parameters are nonlinear and counterintuitive. We show that the shear strength increases as shape deviate from spherical shape. But, for angular shapes it first increases up to a maximum value and then saturates to a constant value as the particles become more angular. For mixture of two shapes, the strength increases with respect of the increase of the proportion of elongated particles, but surprisingly it is independent with the level of homogeneity of the mixture. A detailed analysis of the contact network topology, evidence that various contact types contribute differently to stress transmission at the micro-scale.

  7. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    Science.gov (United States)

    Shi, Guang-Hui; Yang, Qing-Sheng; He, X. Q.

    2013-12-01

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures.

  8. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    International Nuclear Information System (INIS)

    Shi, Guang-Hui; Yang, Qing-Sheng; He, X Q

    2013-01-01

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures. (paper)

  9. Shape memory effect of Fe-14% Mn-6% Si-9% Cr-6% Ni alloy polycrystals

    International Nuclear Information System (INIS)

    Inagaki, Hirosuke

    1992-01-01

    Factors affecting the shape memory effect in Fe-14% Mn-6% Si-9% Cr-6% Ni alloy polycrystals were studied in detail. It was found that the shape memory effect in this alloy was most influenced by the amount of deformation. With increasing amount of deformation, the shape memory effect diminished appreciably. Although the fraction of the initial dimensional change that could be restored was about 45% in the specimen strained by 4%, only 21% of the initial dimensional change was recovered in the specimen strained by 9%. Temperatures of deformation were found to be also an important factor that affected the shape memory effect. The maximum shape memory effect was observed in the specimens strained at temperatures between the M s and M d temperatures. In this alloy, however, specimens strained at temperatures below the M s temperature indicated a relatively large shape memory effect, too. It was further found that the shape memory effect was appreciably intensified by repeated straining and annealing, especially when straining was performed at 500deg C. It was suggested that the shape memory effect in Fe base alloys was strongly influenced by the dislocation substructure present in the starting material. (orig.) [de

  10. Pulse shapes and surface effects in segmented germanium detectors

    International Nuclear Information System (INIS)

    Lenz, Daniel

    2010-01-01

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of 76 Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope 76 Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  11. Pulse shapes and surface effects in segmented germanium detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lenz, Daniel

    2010-03-24

    It is well established that at least two neutrinos are massive. The absolute neutrino mass scale and the neutrino hierarchy are still unknown. In addition, it is not known whether the neutrino is a Dirac or a Majorana particle. The GERmanium Detector Array (GERDA) will be used to search for neutrinoless double beta decay of {sup 76}Ge. The discovery of this decay could help to answer the open questions. In the GERDA experiment, germanium detectors enriched in the isotope {sup 76}Ge are used as source and detector at the same time. The experiment is planned in two phases. In the first, phase existing detectors are deployed. In the second phase, additional detectors will be added. These detectors can be segmented. A low background index around the Q value of the decay is important to maximize the sensitivity of the experiment. This can be achieved through anti-coincidences between segments and through pulse shape analysis. The background index due to radioactive decays in the detector strings and the detectors themselves was estimated, using Monte Carlo simulations for a nominal GERDA Phase II array with 18-fold segmented germanium detectors. A pulse shape simulation package was developed for segmented high-purity germanium detectors. The pulse shape simulation was validated with data taken with an 19-fold segmented high-purity germanium detector. The main part of the detector is 18-fold segmented, 6-fold in the azimuthal angle and 3-fold in the height. A 19th segment of 5mm thickness was created on the top surface of the detector. The detector was characterized and events with energy deposited in the top segment were studied in detail. It was found that the metalization close to the end of the detector is very important with respect to the length of the of the pulses observed. In addition indications for n-type and p-type surface channels were found. (orig.)

  12. History of the Shaped Charge Effect: The First 100 Years

    Science.gov (United States)

    1990-03-22

    patent, wave shapers, follow-through, U.S. 1949 39 6.5-in. ATAR HEAT rocket, U.S. NOTS, 1950 (schematic) 40 Test of 15-in. long standoff shaped charge...Swiss chemist Frederick Schoenbein in 1845, and nitroglycerin, derived by Ascanio Sobrero, professor of Chemistry at the University of Turin, Italy, in...totally new warhead and fuze system and delivery of the first 1000 rounds to Korea in less than 20 days! The 6.5-Inch ATAR (Code Name "RAM") The 6.5

  13. Geometrical effects determinant of the Compton profile shape

    International Nuclear Information System (INIS)

    Sartori, Renzo; Mainardi, R.T.

    1987-01-01

    The main purpose of this work is to evaluate the influence of the experimental set up on the shape of the Compton line. In any scattering experiment, the scattering angle is not well defined due to the collimators aperture and thus, a distribution of angles is found for each set up. This, in turn, produces the energies' distribution of the scattered photons around a mean value. This contribution has been evaluated and found it to be significant for several cases. In order to do this evaluation, a response function, that is numerically generated for each experimental set up and convoluted with the Compton profile, was defined. (Author) [es

  14. Effect of Flow Channel Shape on Performance in Reverse Electrodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kilsung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Deok Han; Kim, Daejoong [Sogang Univ., Seoul (Korea, Republic of)

    2017-05-15

    Reverse electrodialysis (RED), which generates electrical energy from the difference in concentration of two solutions, has been actively studied owing to its high potential and the increased interest in renewable energy resulting from the Paris Agreement on climate change. For RED commercialization, its power density needs to be maximized, and therefore various methods have been discussed. In this paper, the power density was measured using various flow shapes based on the aspect ratio, opening ratio, and number of distribution channels. We found that the power density is enhanced with a decrease in the aspect ratio and an increase in the opening ratio and number of distribution channels.

  15. Effect of plate shapes in orifice plate type flowmeters

    International Nuclear Information System (INIS)

    Moeller, S.V.

    1984-01-01

    The study of unusual plate shapes in orifice plate type flowmeters is presented, with a view to providing data for the substitution of the plate with one centered circular orifice in those applications where its use is not possible. For this purpose, six pairs of plates with different forms, with and without chamfered edges, were made and tested in a closed water loop. Results show that, generally, the use of chamfers improves the results and, in the case of perforated and slotlike orificed plates, the narrow-ness of the fluid passage tends to make unnecessary its use. (Author) [pt

  16. Slope shape effect on runoff and soil erosion under natural rainfall conditions

    OpenAIRE

    Sensoy H; Kara

    2014-01-01

    Slope is often non-uniform along the hillslope, with variations describing concave and convex shapes associated with natural hillslopes. This is because runoff generations vary significantly over short distances, with changes in surface alteration during or between flow events on different slope shapes. The aim of this research is to determine the effects of slope shapes on runoff and soil erosion. A field experiment was conducted from September 2007 to September 2009 on hillside field plots ...

  17. Target shape effects on monoenergetic GeV proton acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Chen Min; Yu Tongpu; Pukhov, Alexander [Institut fuer Theoretische Physik I, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf (Germany); Sheng Zhengming, E-mail: pukhov@tp1.uni-duesseldorf.d [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-04-15

    When a circularly polarized laser pulse interacts with a foil target, there are three stages: pre-hole-boring, hole-boring and light sail acceleration. We study the electron and ion dynamics in the first stage and find the minimum foil thickness requirement for a given laser intensity. Based on this analysis, we propose using a shaped foil for ion acceleration, whose thickness varies transversely to match the laser intensity. Then, the target evolves into three regions: the acceleration, transparency and deformation regions. In the acceleration region, the target can be uniformly accelerated producing a mono-energetic and spatially collimated ion beam. Detailed numerical simulations are performed to check the feasibility and robustness of this scheme, such as the influence of shape factors and surface roughness. A GeV mono-energetic proton beam is observed in three-dimensional particle-in-cell simulations when a laser pulse with a focus intensity of 10{sup 22} W cm{sup -2} is used. The energy conversion efficiency of the laser pulse to the accelerated proton beam with the simulation parameters is more than 23%.

  18. Visual search of illusory contours: Shape and orientation effects

    Directory of Open Access Journals (Sweden)

    Gvozdenović Vasilije

    2008-01-01

    Full Text Available Illusory contours are specific class of visual stimuli that represent stimuli configurations perceived as integral irrespective of the fact that they are given in fragmented uncompleted wholes. Due to their specific features, illusory contours gained much attention in last decade representing prototype of stimuli used in investigations focused on binding problem. On the other side, investigations of illusory contours are related to problem of the level of their visual processing. Neurophysiologic studies show that processing of illusory contours proceed relatively early, on the V2 level, on the other hand most of experimental studies claim that illusory contours are perceived with engagement of visual attention, binding their elements to whole percept. This research is focused on two experiments in which visual search of illusory contours are based on shape and orientation. The main experimental procedure evolved the task proposed by Bravo and Nakayama where instead of detection, subjects were performing identification of one among two possible targets. In the first experiment subjects detected the presence of illusory square or illusory triangle, while in the second experiment subject were detecting two different orientations of illusory triangle. The results are interpreted in terms of visual search and feature integration theory. Beside the type of visual search task, search type proved to be dependent of specific features of illusory shapes which further complicate theoretical interpretation of the level of their perception.

  19. Target shape effects on monoenergetic GeV proton acceleration

    International Nuclear Information System (INIS)

    Chen Min; Yu Tongpu; Pukhov, Alexander; Sheng Zhengming

    2010-01-01

    When a circularly polarized laser pulse interacts with a foil target, there are three stages: pre-hole-boring, hole-boring and light sail acceleration. We study the electron and ion dynamics in the first stage and find the minimum foil thickness requirement for a given laser intensity. Based on this analysis, we propose using a shaped foil for ion acceleration, whose thickness varies transversely to match the laser intensity. Then, the target evolves into three regions: the acceleration, transparency and deformation regions. In the acceleration region, the target can be uniformly accelerated producing a mono-energetic and spatially collimated ion beam. Detailed numerical simulations are performed to check the feasibility and robustness of this scheme, such as the influence of shape factors and surface roughness. A GeV mono-energetic proton beam is observed in three-dimensional particle-in-cell simulations when a laser pulse with a focus intensity of 10 22 W cm -2 is used. The energy conversion efficiency of the laser pulse to the accelerated proton beam with the simulation parameters is more than 23%.

  20. Phase Transformation and Shape Memory Effect of Ti-Pd-Pt-Zr High-Temperature Shape Memory Alloys

    Science.gov (United States)

    Yamabe-Mitarai, Yoko; Takebe, Wataru; Shimojo, Masayuki

    2017-12-01

    To understand the potential of high-temperature shape memory alloys, we have investigated the phase transformation and shape memory effect of Ti-(50 - x)Pt- xPd-5Zr alloys ( x = 0, 5, and 15 at.%), which present the B2 structure in the austenite phase and B19 structure in the martensite phase. Their phase transformation temperatures are very high; A f and M f of Ti-50Pt are 1066 and 1012 °C, respectively. By adding Zr and Pd, the phase transition temperatures decrease, ranging between 804 and 994 °C for A f and 590 and 865 °C for M f. Even at the high phase transformation temperature, a maximum recovery ratio of 70% was obtained for one cycle in a thermal cyclic test. A work output of 1.2 J/cm3 was also obtained. The recovery ratio obtained by the thermal cyclic test was less than 70% because the recovery strain was training effect was also investigated.

  1. Shape memory effect and superelasticity of titanium nickelide alloys implanted with high ion doses

    International Nuclear Information System (INIS)

    Pogrebnjak, A D; Bratushka, S N; Beresnev, V M; Levintant-Zayonts, N

    2013-01-01

    The state of the art in ion implantation of superelastic NiTi shape memory alloys is analyzed. Various technological applications of the shape memory effect are outlined. The principles and techiques of ion implantation are described. Specific features of its application for modification of surface layers in surface engineering are considered. Key properties of shape memory alloys and problems in utilization of ion implantation to improve the surface properties of shape memory alloys, such as corrosion resistance, friction coefficient, wear resistance, etc. are discussed. The bibliography includes 162 references

  2. Facile and sustainable synthesis of shaped iron oxide nanoparticles: effect of iron precursor salts on the shapes of iron oxides.

    Science.gov (United States)

    Sayed, Farheen N; Polshettiwar, Vivek

    2015-05-05

    A facile and sustainable protocol for synthesis of six different shaped iron oxides is developed. Notably, all the six shapes of iron oxides can be synthesised using exactly same synthetic protocol, by simply changing the precursor iron salts. Several of the synthesised shapes are not reported before. This novel protocol is relatively easy to implement and could contribute to overcome the challenge of obtaining various shaped iron oxides in economical and sustainable manner.

  3. The effect of cloud shape on radiative characteristics

    International Nuclear Information System (INIS)

    Welch, R.M.; Zdunkowski, W.G.

    1981-01-01

    Cumulus cloud radiative characteristics are calculated using Monte-Carlo codes as a function of solar zenith angle for clouds approximated by hemispherical, cylindrical and combination-type geometries. Values of cloud reflectivity, transmissivity and absorptivity are compared with values computed from assuming cubic and rectangular geometries, the basis for most previous finite cloud calculations. Poor agreement is obtained at large cloud sizes and only marginal agreement is obtained at small cloud sizes. Two approximations based upon various scalings of cloud optical depth (extinction parameters) are also constructed, but with limited success in reproducing the values produced by the convex shaped clouds. Reasonable agreement among the various approximations occurs at large solar zenith angles, but extremely poor agreement may occur at small angles. (orig./WB) [de

  4. Fast Response, Open-Celled Porous, Shape Memory Effect Actuators with Integrated Attachments

    Science.gov (United States)

    Jardine, Andrew Peter (Inventor)

    2015-01-01

    This invention relates to the exploitation of porous foam articles exhibiting the Shape Memory Effect as actuators. Each foam article is composed of a plurality of geometric shapes, such that some geometric shapes can fit snugly into or around rigid mating connectors that attach the Shape Memory foam article intimately into the load path between a static structure and a moveable structure. The foam is open-celled, composed of a plurality of interconnected struts whose mean diameter can vary from approximately 50 to 500 microns. Gases and fluids flowing through the foam transfer heat rapidly with the struts, providing rapid Shape Memory Effect transformations. Embodiments of porous foam articles as torsional actuators and approximately planar structures are disposed. Simple, integral connection systems exploiting the ability to supply large loads to a structure, and that can also supply hot and cold gases and fluids to effect rapid actuation are also disposed.

  5. Effects of alignment on the roll-over shapes of prosthetic feet.

    Science.gov (United States)

    Hansen, Andrew

    2008-12-01

    Recent work suggests that a prosthetic ankle-foot component's roll-over shape - the effective rocker it conforms to between initial contact and opposite initial contact (the 'roll-over' interval of walking) - is closely linked to its final alignment in the prosthesis (as determined by a skilled prosthetist using heuristic techniques). If true, this information may help to determine the appropriate alignment for a lower limb prosthesis before it is built, or a priori. Knowledge is needed for future models that will incorporate the roll-over shape including the relative effect of alignment on the roll-over shape's radius of curvature and arc length. The purpose of this study was to evaluate the hypotheses that: (i) Changes in prosthesis alignment alter the position and orientation of a foot's roll-over shape in prosthesis-based coordinates, and (ii) these changes occur without changing the radius of curvature or arc length of the roll-over shape. To examine the hypotheses, this study examined the effects of nine alignment settings on the roll-over shapes of two prosthetic feet. The idea that alignment changes move and rotate roll-over shapes of prosthetic feet in prosthesis coordinates is supported by this work, but the hypothesis that the radius of curvature and arc length do not change for different alignments is not strongly supported by the data. A revised approach is presented that explains some of the changes to the roll-over shape parameters due to changes in rotational alignment.

  6. Electron acceleration by laser produced wake field: Pulse shape effect

    Science.gov (United States)

    Malik, Hitendra K.; Kumar, Sandeep; Nishida, Yasushi

    2007-12-01

    Analytical expressions are obtained for the longitudinal field (wake field: Ex), density perturbations ( ne') and the potential ( ϕ) behind a laser pulse propagating in a plasma with the pulse duration of the electron plasma period. A feasibility study on the wake field is carried out with Gaussian-like (GL) pulse, rectangular-triangular (RT) pulse and rectangular-Gaussian (RG) pulse considering one-dimensional weakly nonlinear theory ( ne'/n0≪1), and the maximum energy gain acquired by an electron is calculated for all these three types of the laser pulse shapes. A comparative study infers that the RT pulse yields the best results: In its case maximum electron energy gain is 33.5 MeV for a 30 fs pulse duration whereas in case of GL (RG) pulse of the same duration the gain is 28.6 (28.8)MeV at the laser frequency of 1.6 PHz and the intensity of 3.0 × 10 18 W/m 2. The field of the wake and hence the energy gain get enhanced for the higher laser frequency, larger pulse duration and higher laser intensity for all types of the pulses.

  7. Effects of the shape anisotropy and biasing field on the magnetization reversal process of the diamond-shaped NiFe nano films

    Science.gov (United States)

    Xu, Sichen; Yin, Jianfeng; Tang, Rujun; Zhang, Wenxu; Peng, Bin; Zhang, Wanli

    2017-11-01

    The effects of the planar shape anisotropy and biasing field on the magnetization reversal process (MRP) of the diamond-shaped NiFe nano films have been investigated by micromagnetic simulations. Results show that when the length to width ratio (LWR) of the diamond-shaped film is small, the MRP of the diamond-shaped films are sensitive to LWR. But when LWR is larger than 2, a stable domain switching mode is observed which nucleates from the center of the diamond and then expands to the edges. At a fixed LWR, the magnitude of the switching fields decrease with the increase of the biasing field, but the domain switching mode is not affected by the biasing field. Further analysis shows that demagnetization energy dominates over the MRP of the diamond-shaped films. The above LWR dependence of MRP can be well explained by a variation of the shape anisotropic factor with LWR.

  8. Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications

    Directory of Open Access Journals (Sweden)

    Kazi M. Zakir Hossain

    2015-07-01

    Full Text Available Tubular scaffolds with aligned polylactic acid (PLA fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications.

  9. Nonlinear Model of Pseudoelastic Shape Memory Alloy Damper Considering Residual Martensite Strain Effect

    Directory of Open Access Journals (Sweden)

    Y. M. Parulekar

    2012-01-01

    Full Text Available Recently, there has been increasing interest in using superelastic shape memory alloys for applications in seismic resistant-design. Shape memory alloys (SMAs have a unique property by which they can recover their original shape after experiencing large strains up to 8% either by heating (shape memory effect or removing stress (pseudoelastic effect. Many simplified shape memory alloy models are suggested in the past literature for capturing the pseudoelastic response of SMAs in passive vibration control of structures. Most of these models do not consider the cyclic effects of SMA's and resulting residual martensite deformation. Therefore, a suitable constitutive model of shape memory alloy damper which represents the nonlinear hysterical dynamic system appropriately is essential. In this paper a multilinear hysteretic model incorporating residual martensite strain effect of pseudoelastic shape memory alloy damper is developed and experimentally validated using SMA wire, based damper device. A sensitivity analysis is done using the proposed model along with three other simplified SMA models. The models are implemented on a steel frame representing an SDOF system and the comparison of seismic response of structure with all the models is made in the numerical study.

  10. Shape memory effect in Fe-Mn-Ni-Si-C alloys with low Mn contents

    Energy Technology Data Exchange (ETDEWEB)

    Min, X.H., E-mail: MIN.Xiaohua@nims.go.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Sawaguchi, T.; Ogawa, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Maruyama, T. [Awaji Materia Co., Ltd. 2-3-13, Kanda ogawamachi, Chiyoda, Tokyo 101-0052 (Japan); Yin, F.X. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Tsuzaki, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-0047 (Japan)

    2011-06-15

    Highlights: {yields} A class of new Fe-Mn-Ni-Si-C shape memory alloys with low Mn contents has been designed. {yields} A Mn content for the onset of the {alpha}' martensite is less than 13 mass%, and the {epsilon} martensite still exists in the alloy with a 9 mass% Mn. {yields} The shape recovery strain decreases considerably when the Mn content is reduced from 13 to 11 mass%. {yields} The sudden decrease in the shape recovery strain is mainly caused by the formation of {alpha}' martensite. - Abstract: An attempt was made to develop a new Fe-Mn-Si-based shape memory alloy from a Fe-17Mn-6Si-0.3C (mass%) shape memory alloy, which was previously reported to show a superior shape memory effect without any costly training treatment, by lowering its Mn content. The shape memory effect and the phase transformation behavior were investigated for the as-solution treated Fe-(17-2x)Mn-6Si-0.3C-xNi (x = 0, 1, 2, 3, 4) polycrystalline alloys. The shape recovery strain exceeded 2% in the alloys with x = 0-2, which is sufficient for an industrially applicable shape memory effect; however, it suddenly decreased in the alloys between x = 2 and 3 although the significant shape recovery strain still exceeded 1%. In the alloys with x = 3 and 4, X-ray diffraction analysis and transmission electron microscope observation revealed the existence of {alpha}' martensite, which forms at the intersection of the {epsilon} martensite plates and suppresses the crystallographic reversibility of the {gamma} austenite to {epsilon} martensitic transformation.

  11. Shape and size effects on layered Ni/PZT/Ni composites magnetoelectric performance

    Energy Technology Data Exchange (ETDEWEB)

    Pan, D A; Zhang, S G; Qiao, L J [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A [Department of Mechanical Engineering, University of South Florida, Tampa FL 33620 (United States)], E-mail: lqiao@ustb.edu.cn

    2008-09-07

    This paper presents the magnetoelectric (ME) effect in trilayered Ni/PZT/Ni composites which is related to their size and shape. The ME composites with the same interfacial areas but different geometrical shapes have different ME voltage coefficients. Longitudinal resonant modes in the rectangular and triangular trilayered ME composites were studied. One should choose optimized size, shape and working frequency of the ME composites in order to gain the maximum ME effect. This study plays a guiding role for trilayered ME composites design for real applications. (fast track communication)

  12. A review on the martensitic transformation and shape memory effect in Fe-Mn-Si alloys

    International Nuclear Information System (INIS)

    Gu, Q.; Humbeeck, J. van; Delaey, L.

    1994-01-01

    The martensitic transformation and the shape memory effect in Fe-Mn-Si alloys received great attention recently due to its potential commercial value. In this paper, the mechanisms for the martensitic transformation and various parameters influencing the shape memory effect like alloy composition, applied stress, prestrain, crystal orientation, temperature, grain size, pre-existing martensite, thermal cycling and training etc. are reviewed and discussed. (orig.)

  13. Effect of the shape of a nano-object on quantum-size states

    International Nuclear Information System (INIS)

    Dzyuba, Vladimir; Kulchin, Yurii; Milichko, Valentin

    2012-01-01

    In this paper, we propose an original functional method that makes it easy to determine the effect of any deviation in the shape of a nano-object from the well-studied shape (e.g., spherical) on the quantum characteristics of charge localized inside the nano-object. The maximum dimension of the object is determined by the magnitude of influence of quantum-size effects on quantum states of charge, and is limited by 100 nm. This method is ideologically similar to the perturbation theory, but the perturbation of the surface shape, rather than the potential, is used. Unlike the well-known variational methods of theoretical physics, this method is based on the assumption that the physical quantity is a functional of surface shape. Using the method developed, we present the quantum-size state of charges for two different complex shapes of nano-objects. The results from analyzing the quantum-size states of charge in the nano-objects with a deformed spherical shape indicated that the shape perturbations have a larger effect on the probability density of locating a particle inside the nano-object than on the surface energy spectrum and quantum density of the states.

  14. Synthesis and evaluation of ageing effect on Cu–Al–Be–Mn quaternary Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    A.G. Shivasiddaramiah

    2016-09-01

    Full Text Available Copper based shape memory alloy exhibits high transformation temperature and ability to differ the achieved properties through alloying additions. A quaternary Cu–Al–Be–Mn shape memory alloys of 0.2–0.4 wt% of manganese, 0.4–0.5 wt% of Beryllium and 10–14 wt% of aluminium with remaining copper, showing β-phase at higher temperature and show shape memory effect when quenching to lower temperatures, SMA's were prepared by induction melting. The objective is to study the effect of thermal ageing at different temperatures Af (above austenitic phase finish temperature and at different time on shape memory effect and transformation temperatures. The aged specimens or SMA's were studied by DSC, OM and hardness measurements. The results from this study help to find the applications in different thermal conditions.

  15. Effect of forward/backward standing posture on foot shape

    NARCIS (Netherlands)

    Daanen, H.A.M.; Tan, T.K.; Punte, P.A.J.

    2000-01-01

    Foot length and breadth are generally used to determine the correct shoe size. An important question is whether foot length and foot breadth are dependent upon body posture. Therefore, the effect of leaning forward/backward on foot length and breadth is investigated in this study. Seven subjects

  16. Effects of fin shape on condensation in herringbone microfin tubes

    Energy Technology Data Exchange (ETDEWEB)

    Miyara, Akio [Saga University (Japan). Dept. of Mechanical Engineering; Otsubo, Yusuke; Ohtsuka, Satoshi; Mizuta, Yoshihiko [Saga University (Japan). Graduate School of Science and Engineering

    2003-06-01

    Effects of fin height and helix angle on condensation inside a herringbone microfin tube have been experimentally investigated with five types of herringbone microfin tubes. Heat transfer coefficients are about 2-4 times higher than that of the helical microfin tube under high mass velocity conditions. In the low mass velocity, they are equal to that of the helical microfin tube. The heat transfer enhancement increases with fin height up to 0.18 mm; higher fin heights show enhancement values similar to the 0.18 mm results. Pressure drop increases with the fin height. Larger helix angle yields higher heat transfer and higher pressure drop. For the lowest fin and/or smallest helix angle, the pressure drop is comparable with that of the helical microfin tube, while the heat transfer enhancement is higher. The enhancement mechanism is discussed from flow pattern observations. Effect of mass transfer resistance for R410A is estimated and negligible effects have been proved. (author)

  17. Fast Response Shape Memory Effect Titanium Nickel (TiNi) Foam Torque Tubes

    Science.gov (United States)

    Jardine, Peter

    2014-01-01

    Shape Change Technologies has developed a process to manufacture net-shaped TiNi foam torque tubes that demonstrate the shape memory effect. The torque tubes dramatically reduce response time by a factor of 10. This Phase II project matured the actuator technology by rigorously characterizing the process to optimize the quality of the TiNi and developing a set of metrics to provide ISO 9002 quality assurance. A laboratory virtual instrument engineering workbench (LabVIEW'TM')-based, real-time control of the torsional actuators was developed. These actuators were developed with The Boeing Company for aerospace applications.

  18. Effect of particle shapes on effective strain gradient of SiC particle reinforced aluminum composites

    International Nuclear Information System (INIS)

    Liu, X; Cao, D F; Mei, H; Liu, L S; Lei, Z T

    2013-01-01

    The stress increments depend not only on the plastic strain but also on the gradient of plastic strain, when the characteristic length scale associated with non-uniform plastic deformation is on the order of microns. In the present research, the Taylor-based nonlocal theory of plasticity (TNT plasticity), with considering both geometrically necessary dislocations and statistically stored dislocations, is applied to investigated the effect of particle shapes on the strain gradient and mechanical properties of SiC particle reinforced aluminum composites (SiC/Al composites). Based on this theory, a two-dimensional axial symmetry cell model is built in the ABAQUS finite element code through its USER-ELEMENT (UEL) interface. Some comparisons with the classical plastic theory demonstrate that the effective stress predicted by TNT plasticity is obviously higher than that predicted by classical plastic theory. The results also demonstrate that the irregular particles cause higher effective gradient strain which is attributed to the fact that angular shape particles give more geometrically.

  19. Micrometer-scale 3-D shape characterization of eight cements: Particle shape and cement chemistry, and the effect of particle shape on laser diffraction particle size measurement

    International Nuclear Information System (INIS)

    Erdogan, S.T.; Nie, X.; Stutzman, P.E.; Garboczi, E.J.

    2010-01-01

    Eight different portland cements were imaged on a synchrotron beam line at Brookhaven National Laboratory using X-ray microcomputed tomography at a voxel size of about 1 μm per cubic voxel edge. The particles ranged in size roughly between 10 μm and 100 μm. The shape and size of individual particles were computationally analyzed using spherical harmonic analysis. The particle shape difference between cements was small but significant, as judged by several different quantitative shape measures, including the particle length, width, and thickness distributions. It was found that the average shape of cement particles was closely correlated with the volume fraction of C 3 S (alite) and C 2 S (belite) making up the cement powder. It is shown that the non-spherical particle shape of the cements strongly influence laser diffraction results, at least in the sieve size range of 20 μm to 38 μm. Since laser diffraction particle size measurement is being increasingly used by the cement industry, while cement chemistry is always a main factor in cement production, these results could have important implications for how this kind of particle size measurement should be understood and used in the cement industry.

  20. Effects of groove shape of notch on the flow characteristics of spool valve

    International Nuclear Information System (INIS)

    Ye, Yi; Yin, Chen-Bo; Li, Xing-Dong; Zhou, Wei-jin; Yuan, Feng-feng

    2014-01-01

    Highlights: • Flow characteristics of notches are studied using CFD simulation and experiment. • Test data is fitted by least square method to analyze discharge coefficient. • The stable value of discharge coefficient is deduced. • Effects of groove shape on steady flow force and throttling stiffness are performed. • The groove shape has significant effects on the flow characteristics. - Abstract: The grooves of notches of hydraulic spool valves are usually designed into various shapes for their desired flow characteristics. The aim of this paper is to clarify the effects of the groove shape on the flow characteristics through computational fluid dynamics (CFD) and experimental investigations. The RNG k–ε turbulence model is used to simulate the pressure distributions of the flow fields inside three notches with their corresponding typical structural grooves in order to analyze the changes of restricted locations along with the openings and, furthermore, to calculate the flow areas of the notches. The accuracy of the employed model is demonstrated by comparing the computational results with the experimental data. Additionally, the flow rate vs. pressure drop data obtained from the experiment is fitted by least square method. On this basis, the discharge coefficient as a function of groove geometry, flow condition, fitting coefficients and its stable value is deduced, proving to be quite consistent with the experimental result. Thanks to the jet flow angles estimated by CFD simulation, the steady flow forces are calculated, which show good agreement with the experimental results except for some small differences. Finally, the throttling stiffness of the three notches is investigated, with that of divergent U-shape groove falls between spheroid-shape groove and triangle-shape groove. Similar results are found for steady flow force. The results indicate that the groove shape has significant effects on the flow characteristics (flow area, discharge

  1. Effect of Jet Shape on Flow and Torque Characteristics of Pelton Turbine Runner

    OpenAIRE

    Vishal Gupta,; Dr. Vishnu Prasad

    2014-01-01

    In Pelton turbine, the energy carried by water is converted into kinetic energy by providing nozzle at the end of penstock. The shape of jet affects the force and torque on the bucket and runner of turbine. The nozzle of circular cross section is commonly used. In this paper attempt has been made to study the effect of four different jet shapes on the flow and torque characteristics of Pelton turbine runner through numerical simulation.

  2. Effect of Ternary Addition of Iron on Shape Memory Characteristics of Cu-Al Alloys

    Science.gov (United States)

    Raju, T. N.; Sampath, V.

    2011-07-01

    The effect of alloying Cu-Al alloys with Fe on their transformation temperatures and shape memory properties was investigated by differential scanning calorimetry and bend test. It was found that the minor additions of iron resulted in change of transformation temperatures and led to excellent shape memory properties of the alloys. Since the transformation temperatures are high, they are an ideal choice for high-temperature applications.

  3. The effects of noise over the complete space of diffusion tensor shape.

    Science.gov (United States)

    Gahm, Jin Kyu; Kindlmann, Gordon; Ennis, Daniel B

    2014-01-01

    Diffusion tensor magnetic resonance imaging (DT-MRI) is a technique used to quantify the microstructural organization of biological tissues. Multiple images are necessary to reconstruct the tensor data and each acquisition is subject to complex thermal noise. As such, measures of tensor invariants, which characterize components of tensor shape, derived from the tensor data will be biased from their true values. Previous work has examined this bias, but over a narrow range of tensor shape. Herein, we define the mathematics for constructing a tensor from tensor invariants, which permits an intuitive and principled means for building tensors with a complete range of tensor shape and salient microstructural properties. Thereafter, we use this development to evaluate by simulation the effects of noise on characterizing tensor shape over the complete space of tensor shape for three encoding schemes with different SNR and gradient directions. We also define a new framework for determining the distribution of the true values of tensor invariants given their measures, which provides guidance about the confidence the observer should have in the measures. Finally, we present the statistics of tensor invariant estimates over the complete space of tensor shape to demonstrate how the noise sensitivity of tensor invariants varies across the space of tensor shape as well as how the imaging protocol impacts measures of tensor invariants. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Angle-resolved effective potentials for disk-shaped molecules

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, Thomas, E-mail: thomas.heinemann@tu-berlin.de; Klapp, Sabine H. L., E-mail: klapp@physik.tu-berlin.de [Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Palczynski, Karol, E-mail: karol.palczynski@helmholtz-berlin.de; Dzubiella, Joachim, E-mail: joachim.dzubiella@helmholtz-berlin.de [Institut für Physik, Humboldt Universität zu Berlin, Newtonstraße 15, 12489 Berlin (Germany); Helmholtz Zentrum Berlin (HZB), Institute of Soft Matter and Functional Materials, Hahn-Meitner Platz 1, 14109 Berlin (Germany)

    2014-12-07

    We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van der Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in more efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many-particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations.

  5. Effect of precipitation on the shape memory effect of Ti50Ni25Cu25 melt-spun ribbon

    International Nuclear Information System (INIS)

    Tong Yunxiang; Liu Yong; Xie Zeliang; Zarinejad, Mehrdad

    2008-01-01

    The present research aims to provide accurate understanding of the relation between precipitation (volume fraction, morphology, type) and shape memory effect of Ti 50 Ni 25 Cu 25 melt-spun ribbon. Rapid thermal annealing was used to control the microstructural development while the shape memory effect of the ribbon was determined under constraint thermal cycling. The results show that the precipitation process takes the following sequence: B11 TiCu → B11 TiCu + Ti 2 (Ni, Cu) → Ti 2 (Ni, Cu) with increasing annealing temperature or duration. The shape memory effect is found to depend on both the volume fraction and the distribution of the precipitates. The former affects the shape recovery strain through reduction of the transformation volume participating the shape recovery. The latter affects the shape recovery strain through strengthening the matrix thus reducing the martensite strain which is more predominant under low constraint stresses. Precipitation strengthening, on the other hand, reduces the tendency of dislocation generation/movement, thus reducing the irreversible strain and improving shape recovery strain. This understanding provides guidelines on the optimization of the shape memory properties of the Ti 50 Ni 25 Cu 25 melt-spun ribbon via post-processing annealing

  6. Preparation and evaluation of ageing effect of Cu-Al-Be-Mn shape memory alloys

    Science.gov (United States)

    Shivasiddaramaiah, A. G.; Mallik, U. S.; Mahato, Ranjit; Shashishekar, C.

    2018-04-01

    10-14 wt. % of aluminum, 0.3-0.6 wt. % of beryllium and 0.1-0.4 wt. % of manganese and remaining copper melted in the induction furnace through ingot metallurgy. The prepared SMAs are subjected to homogenization. It was observed that the samples exhibits β-phase at high temperature and shape memory effect after going through step quenching to a low temperature. Scanning Electron Microscope, DSC, bending test were performed on the samples to determine the microstructure, transformation temperatures and shape memory effect respectively. The alloy exhibit good shape memory effect, up to around 96% strain recovery by shape memory effect. The ageing is performed on the specimen prepared according to ASTM standard for testing micro-hardness and tensile test. Precipitation hardening method was employed to age the samples and they were aged at different temperature and at different times followed by quenching. Various forms of precipitates were formed. It was found that the formation rate and transformation temperature increased with ageing time, while the amount of precipitate had an inverse impact on strain recovery by shape memory effect. The result expected is to increase in mechanical properties of the material such as hardness.

  7. Composition dependence of phase transformation behavior and shape memory effect of Ti(Pt, Ir)

    International Nuclear Information System (INIS)

    Yamabe-Mitarai, Y.; Hara, T.; Kitashima, T.; Miura, S.; Hosoda, H.

    2013-01-01

    Highlights: ► The partial isothemal section at 1523 K was determined in Ti–Pt–Ir. ► The high-temperature shape memory effect of Ti(Pt, Ir) was investigated. ► The shape recovery ratio was 72% in Ti–10Pt–32Ir after deformation at 1123 K. ► Ir addition to TiPt is effective to improve shape memory effect of TiPt. -- Abstract: The phase transformation and high-temperature shape memory effect of Ti(Pt, Ir) were investigated. First, the Ti-rich phase boundary of Ti(Pt, Ir) was investigated by phase composition analysis by secondary electron microscopy (SEM) using an electron probe X-ray micro analyzer (EPMA), X-ray diffraction analysis and transmission electron microscopy (TEM). Then, the three alloys Ti–35Pt–10Ir, Ti–22Pt–22Ir, and Ti–10Pt–32Ir (at%) close to the phase boundary but in the single phase of Ti(Pt, Ir) were prepared by the arc melting method. The shape memory effect and crystal structure were investigated by compression loading–unloading tests and high-temperature X-ray diffraction analysis, respectively

  8. Comparison of the effectiveness of alternative feature sets in shape retrieval of multicomponent images

    Science.gov (United States)

    Eakins, John P.; Edwards, Jonathan D.; Riley, K. Jonathan; Rosin, Paul L.

    2001-01-01

    Many different kinds of features have been used as the basis for shape retrieval from image databases. This paper investigates the relative effectiveness of several types of global shape feature, both singly and in combination. The features compared include well-established descriptors such as Fourier coefficients and moment invariants, as well as recently-proposed measures of triangularity and ellipticity. Experiments were conducted within the framework of the ARTISAN shape retrieval system, and retrieval effectiveness assessed on a database of over 10,000 images, using 24 queries and associated ground truth supplied by the UK Patent Office . Our experiments revealed only minor differences in retrieval effectiveness between different measures, suggesting that a wide variety of shape feature combinations can provide adequate discriminating power for effective shape retrieval in multi-component image collections such as trademark registries. Marked differences between measures were observed for some individual queries, suggesting that there could be considerable scope for improving retrieval effectiveness by providing users with an improved framework for searching multi-dimensional feature space.

  9. The effect of shape on drag: a physics exercise inspired by biology

    Science.gov (United States)

    Fingerut, Jonathan; Johnson, Nicholas; Mongeau, Eric; Habdas, Piotr

    2017-07-01

    As part of a biomechanics course aimed at upper-division biology and physics majors, but applicable to a range of student learning levels, this laboratory exercise provides an insight into the effect of shape on hydrodynamic performance, as well an introduction to computer aided design (CAD) and 3D printing. Students use hydrodynamic modeling software and simple CAD programs to design a shape with the least amount of drag based on strategies gleaned from the study of natural forms. Students then print the shapes using a 3D printer and test their shapes against their classmates in a friendly competition. From this exercise, students gain a more intuitive sense of the challenges that organisms face when moving through fluid environments, the physical phenomena involved in moving through fluids at high Reynolds numbers and observe how and why certain morphologies, such as streamlining, are common answers to the challenge of swimming at high speeds.

  10. Effect of titanium addition on shape memory effect and recovery stress of training-free cast Fe–Mn–Si–Cr–Ni shape memory alloys

    International Nuclear Information System (INIS)

    Wang, Gaixia; Peng, Huabei; Sun, Panpan; Wang, Shanling; Wen, Yuhua

    2016-01-01

    The shape memory effect and recovery stress of cast Fe–17.2Mn–5.28Si–9.8Cr–4.57Ni (18Mn) and Fe–17.5Mn–5.29Si–9.68Cr–4.2Ni–0.09Ti (18Mn–Ti) alloys have been investigated by optical microscopy, scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and resistivity–temperature curves. The cast 18Mn and 18Mn–Ti alloys solidified as the ferritic mode for which liquid phase fully transforms into primary δ ferrite. The role of titanium is to indirectly refine the austenite through refining the primary δ ferrite. In this case, the austenitic grains of the cast 18Mn alloy were much bigger than that of the cast 18Mn–Ti alloy, although the two alloys underwent δ→γ phase transformation. Grain refinement suppresses the stress-induced ε martensitic transformation, and thus the shape memory effect of the cast 18Mn–Ti alloy is worse than that of the cast 18Mn alloy. On the contrary, the maximum recovery stress and the recovery stress at room temperature are higher for the cast 18Mn–Ti alloy annealed at 1073 K for 30 min than for the cast 18Mn alloy annealed at 973 K for 30 min, because grain refinement suppresses the relaxation of recovery stress caused by the plastic deformation and the stress-induced ε martensitic transformation during cooling process. It is difficult to obtain the training-free cast Fe–Mn–Si based shape memory alloys with excellent shape memory effect and high recovery stress only by grain refinement.

  11. Shape representation modulating the effect of motion on visual search performance.

    Science.gov (United States)

    Yang, Lindong; Yu, Ruifeng; Lin, Xuelian; Liu, Na

    2017-11-02

    The effect of motion on visual search has been extensively investigated, but that of uniform linear motion of display on search performance for tasks with different target-distractor shape representations has been rarely explored. The present study conducted three visual search experiments. In Experiments 1 and 2, participants finished two search tasks that differed in target-distractor shape representations under static and dynamic conditions. Two tasks with clear and blurred stimuli were performed in Experiment 3. The experiments revealed that target-distractor shape representation modulated the effect of motion on visual search performance. For tasks with low target-distractor shape similarity, motion negatively affected search performance, which was consistent with previous studies. However, for tasks with high target-distractor shape similarity, if the target differed from distractors in that a gap with a linear contour was added to the target, and the corresponding part of distractors had a curved contour, motion positively influenced search performance. Motion blur contributed to the performance enhancement under dynamic conditions. The findings are useful for understanding the influence of target-distractor shape representation on dynamic visual search performance when display had uniform linear motion.

  12. Effect of initial longitudinal stresses on the linearity of the shape rolled products after accelerated cooling

    International Nuclear Information System (INIS)

    Shetulov, D.I.

    1991-01-01

    Consideration is given to results of investigation into effect of initial longitudinal stresses on the linearity of the shaped rolled products after accelerated cooling. Particular attention is placed on the influence of an initial stresses state of material on qualiti of heat-treated rolled products. Effect of stresses state of worked material residual bending is studed by the use of computerized simulation.Theoretical analysis of stress-strain state of shape hot-rolled products during accelerated cooling after finishing stand of rolls is developed. A residual stress-strain state of material does not affected by rolling stresses when using a rautine cooling device with rigid centering of the product under rolling. It is expected that the effect of initial stresses could be significant in the absence of a limitator for bending deformation of shaped product longitudinal axis

  13. The effect of bacterial cellulose on the shape memory behavior of polyvinyl alcohol nanocomposite hydrogel

    Science.gov (United States)

    Pirahmadi, Pegah; Kokabi, Mehrdad

    2018-01-01

    Most research on shape memory polymers has been confined to neat polymers in their dry state, while, some hydrogel networks are known for their shape memory properties. Hydrogels have low glass transition temperatures which are below 100°C depend on the content of water. But they are usually weak and brittle, and not suitable for structural applications due to their low mechanical strengths because of these materials have large amount of water (>50%), so they could not remember original shape perfectly. Bacterial cellulose nanofibers with perfect properties such as high water holding capacity, high crystallinity, high tensile strength and good biocompatibility can dismiss all the drawbacks. In the present study, polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel prepared by repetitive freezing-thawing method. The bacterial cellulose was used as reinforcement to improve the mechanical properties and stimuli response. Differential scanning calorimetry was employed to obtain the glass transition temperature. Nanocomposite morphology was characterized by field-emission scanning electron microscopy and mechanical properties were investigated by standard tensile test. Finally, the effect of bacterial cellulose nanofiber on shape memory behavior of polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel was investigated. It is found that switching temperature of this system is the glass transition temperature of the nano domains formed within the system. The results also show increase of shape recovery, and shape recovery speed due to presence of bacterial cellulose.

  14. Mechanical properties and shape memory effect of thermal-responsive polymer based on PVA

    Science.gov (United States)

    Lin, Liulan; Zhang, Lingfeng; Guo, Yanwei

    2018-01-01

    In this study, the effect of content of glutaraldehyde (GA) on the shape memory behavior of a shape memory polymer based on polyvinyl alcohol chemically cross-linked with GA was investigated. Thermal-responsive shape memory composites with three different GA levels, GA-PVA (3 wt%, 5 wt%, 7 wt%), were prepared by particle melting, mold forming and freeze-drying technique. The mechanical properties, thermal properties and shape memory behavior were measured by differential scanning calorimeter, physical bending test and cyclic thermo-mechanical test. The addition of GA to PVA led to a steady shape memory transition temperature and an improved mechanical compressive strength. The composite with 5 wt% of GA exhibited the best shape recoverability. Further increase in the crosslinking agent content of GA would reduce the recovery force and prolong the recovery time due to restriction in the movement of the soft PVA chain segments. These results provide important information for the study on materials in 4D printing.

  15. Effect of weld line shape on material flow during friction stir welding of aluminum and steel

    International Nuclear Information System (INIS)

    Yasui, Toshiaki; Ando, Naoyuki; Morinaka, Shinpei; Mizushima, Hiroki; Fukumoto, Masahiro

    2014-01-01

    The effect of weld line shape on material flow during the friction stir welding of aluminum and steel was investigated. The material flow velocity was evaluated with simulated experiments using plasticine as the simulant material. The validity of the simulated experiments was verified by the marker material experiments on aluminum. The circumferential velocity of material around the probe increased with the depth from the weld surface. The effect is significant in cases where the advancing side is located on the outside of curve and those with higher curvature. Thus, there is an influence of weld line shape on material flow

  16. Effect of ternary alloying elements on the shape memory behavior of Ti-Ta alloys

    International Nuclear Information System (INIS)

    Buenconsejo, Pio John S.; Kim, Hee Young; Miyazaki, Shuichi

    2009-01-01

    The effect of ternary alloying elements (X = V, Cr, Fe, Zr, Hf, Mo, Sn, Al) on the shape memory behavior of Ti-30Ta-X alloys was investigated. All the alloying elements decreased the martensitic transformation temperatures. The decrease in the martensitic transformation start (M s ) temperature due to alloying was affected by the atomic size and number of valence electrons of the alloying element. A larger number of valence electrons and a smaller atomic radius of an alloying element decreased the M s more strongly. The effect of the alloying elements on suppressing the aging effect on the shape memory behavior was also investigated. It was found that the additions of Sn and Al to Ti-Ta were effective in suppressing the effect of aging on the shape memory behavior, since they strongly suppress the formation of ω phase during aging treatment. For this reason the Ti-30Ta-1Al and Ti-30Ta-1Sn alloys exhibited a stable high-temperature shape memory effect during thermal cycling.

  17. Human vision model in relation to characteristics of shapes for the Mach band effect.

    Science.gov (United States)

    Wu, Bo-Wen; Fang, Yi-Chin

    2015-10-01

    For human vision to recognize the contours of objects means that, as the contrast variation at the object's edges increases, so will the Mach band effect of human vision. This paper more deeply investigates the relationship between changes in the contours of an object and the Mach band effect of human vision. Based on lateral inhibition and the Mach band effect, we studied subjects' eyes as they watched images of different shapes under a fixed brightness at 34  cd/m2, with changes of contrast and spatial frequency. Three types of display were used: a television, a computer monitor, and a projector. For each display used, we conducted a separate experiment for each shape. Although the maximum values for the contrast sensitivity function curves of the displays were different, their variations were minimal. As the spatial frequency changed, the diminishing effect of the different lines also was minimal. However, as the shapes at the contour intersections were modified by the Mach band effect, a greater degree of variation occurred. In addition, as the spatial frequency at a contour intersection increased, the Mach band effect became lower, along with changes in the corresponding contrast sensitivity function curve. Our experimental results on the characteristics of human vision have led to what we believe is a new vision model based on tests with different shapes. This new model may be used for future development and implementation of an artificial vision system.

  18. Pseudo-elasticity and shape memory effect on the TiNiCoV alloy

    International Nuclear Information System (INIS)

    Hsu, S.E.; Yeh, M.T.; Hsu, I.C.; Chang, S.K.; Dai, Y.C.; Wang, J.Y.

    2000-01-01

    Unlike most of the structural intermetallic compound, TiNi is an exceptional case of inherent ductility. Besides its amusing behavior of high damping capacity due to martensitic transformation, the duel properties of shape memory and pseudo-elasticity co-exhibited in the same V and Co-modified TiNi-SMA at various temperature will attract another attention in modern manufacturing technology. The objective of this paper is to investigate the pseudo-elasticity and strain rate effect on TiNiCoV-SMA. The presence of dual behavior of super-elasticity and shape memory effect is technological significant for application of advanced materials on the structural component. An illustration of application of TiNiCoV shape memory alloy on the face of golf club head will be presented in this paper. (orig.)

  19. Thermodynamic assessment of the stabilization effect in deformed shape memory alloy martensite

    International Nuclear Information System (INIS)

    Kato, Hiroyuki; Yasuda, Yohei; Sasaki, Kazuaki

    2011-01-01

    When a martensitic shape memory alloy is deformed, the reverse transformation occurs at higher temperature than that of undeformed martensite. This is a typical case of the stabilization effect of martensite that is commonly observed in shape memory alloys. Regarding previous results measured by electric resistance and/or dilatometoric methods in NiTi and CuAlNi shape memory alloys, this study has performed calorimetric measurement in these alloys in order to re-examine the stabilization effect in terms of thermodynamics. Experimental evidence for appreciable changes in the reverse transformation temperature due to variant change of the martensite is presented. The elastic energy stored in the deformed martensite and the irreversible energy dissipated during the reverse transformation are estimated from the transformation temperatures, the stress-strain curves of the martensite and the latent heat of transformation. The temperatures of the reverse martensitic transformation have been related to these energies in explicit form.

  20. Shape-memory effect of nanocomposites based on liquid-crystalline elastomers

    Science.gov (United States)

    Marotta, A.; Lama, G. C.; Gentile, G.; Cerruti, P.; Carfagna, C.; Ambrogi, V.

    2016-05-01

    In this work, nanocomposites based on liquid crystalline (LC) elastomers were prepared and characterized in their shape memory properties. For the synthesis of materials, p-bis(2,3-epoxypropoxy)-α-methylstilbene (DOMS) was used as mesogenic epoxy monomer, sebacic acid (SA) as curing agent and multi-walled carbon nanotubes (MWCNT) and graphene oxide (GO) as fillers. First, an effective compatibilization methodology was set up to improve the interfacial adhesion between the matrix and the carbonaceous nanofillers, thus obtaining homogeneous distribution and dispersion of the nanofillers within the polymer phase. Then, the obtained nanocomposite films were characterized in their morphological and thermal properties. In particular, the effect of the addition of the nanofillers on liquid crystalline behavior, as well as on shape-memory properties of the realized materials was investigated. It was found that both fillers were able to enhance the thermomechanical response of the LC elastomers, making them good candidates as shape memory materials.

  1. Effect of cathode shape on vertical buffered electropolishing for niobium SRF cavities

    Science.gov (United States)

    Jin, S.; Wu, A. T.; Lu, X. Y.; Rimmer, R. A.; Lin, L.; Zhao, K.; Mammosser, J.; Gao, J.

    2013-09-01

    This paper reports the research results of the effect of cathode shape during vertical buffered electropolishing (BEP) by employing a demountable single cell niobium (Nb) superconducting radio frequency (SRF) cavity. Several different cathode shapes such as, for instance, bar, ball, ellipsoid, and wheels of different diameters have been tested. Detailed electropolishing parameters including I-V characteristic, removal rate, surface roughness, and polishing uniformity at different locations inside the demountable cavity are measured. Similar studies are also done on conventional electropolishing (EP) for comparison. It is revealed that cathode shape has dominant effects for BEP especially on the obtaining of a suitable polishing condition and a uniform polishing rate in an Nb SRF single cell cavity. EP appears to have the same tendency. This paper demonstrates that a more homogeneous polishing result can be obtained by optimizing the electric field distribution inside the cavity through the modification of the cathode shape given the conditions that temperature and electrolyte flow are kept constant. Electric field distribution and electrolyte flow patterns inside the cavity are simulated via Poisson-Superfish and Solidworks respectively. With the optimal cathode shape, BEP shows a much faster polishing rate of ∼2.5 μm/min and is able to produce a smoother surface finish in the treatments of single cell cavities in comparison with EP.

  2. The shape-memory effect in ionic elastomers: fixation through ionic interactions.

    Science.gov (United States)

    González-Jiménez, Antonio; Malmierca, Marta A; Bernal-Ortega, Pilar; Posadas, Pilar; Pérez-Aparicio, Roberto; Marcos-Fernández, Ángel; Mather, Patrick T; Valentín, Juan L

    2017-04-19

    Shape-memory elastomers based on a commercial rubber cross-linked by both ionic and covalent bonds have been developed. The elastomeric matrix was a carboxylated nitrile rubber (XNBR) vulcanized with magnesium oxide (MgO) providing ionic interactions that form hierarchical structures. The so-named ionic transition is used as the unique thermal transition responsible for the shape-memory effect (SME) in these elastomers. These ionic interactions fix the temporary shape due to their behavior as dynamic cross-links with temperature changes. Covalent cross-links were incorporated with the addition of different proportions of dicumyl peroxide (DCP) to the ionic elastomer to establish and recover the permanent shape. In this article, the SME was modulated by modifying the degree of covalent cross-linking, while keeping the ionic contribution constant. In addition, different programming parameters, such as deformation temperature, heating/cooling rate, loading/unloading rate and percentage of tensile strain, were evaluated for their effects on shape-memory behavior.

  3. Effect of sample shape on nonlinear magnetization dynamics under an external magnetic field

    International Nuclear Information System (INIS)

    Vagin, Dmitry V.; Polyakov, Oleg P.

    2008-01-01

    Effect of sample shape on the nonlinear collective dynamics of magnetic moments in the presence of oscillating and constant external magnetic fields is studied using the Landau-Lifshitz-Gilbert (LLG) approach. The uniformly magnetized sample is considered to be an ellipsoidal axially symmetric particle described by demagnetization factors and uniaxial crystallographic anisotropy formed some angle with an applied field direction. It is investigated as to how the change in particle shape affects its nonlinear magnetization dynamics. To produce a regular study, all results are presented in the form of bifurcation diagrams for all sufficient dynamics regimes of the considered system. In this paper, we show that the sample's (particle's) shape and its orientation with respect to the external field (system configuration) determine the character of magnetization dynamics: deterministic behavior and appearance of chaotic states. A simple change in the system's configuration or in the shapes of its parts can transfer it from chaotic to periodic or even static regime and back. Moreover, the effect of magnetization precession stall and magnetic moments alignment parallel or antiparallel to the external oscillating field is revealed and the way of control of such 'polarized' states is found. Our results suggest that varying the particle's shape and fields' geometry may provide a useful way of magnetization dynamics control in complex magnetic systems

  4. Effect of cathode shape on vertical buffered electropolishing for niobium SRF cavities

    International Nuclear Information System (INIS)

    Jin, S.; Wu, A.T.; Lu, X.Y.; Rimmer, R.A.; Lin, L.; Zhao, K.; Mammosser, J.; Gao, J.

    2013-01-01

    This paper reports the research results of the effect of cathode shape during vertical buffered electropolishing (BEP) by employing a demountable single cell niobium (Nb) superconducting radio frequency (SRF) cavity. Several different cathode shapes such as, for instance, bar, ball, ellipsoid, and wheels of different diameters have been tested. Detailed electropolishing parameters including I–V characteristic, removal rate, surface roughness, and polishing uniformity at different locations inside the demountable cavity are measured. Similar studies are also done on conventional electropolishing (EP) for comparison. It is revealed that cathode shape has dominant effects for BEP especially on the obtaining of a suitable polishing condition and a uniform polishing rate in an Nb SRF single cell cavity. EP appears to have the same tendency. This paper demonstrates that a more homogeneous polishing result can be obtained by optimizing the electric field distribution inside the cavity through the modification of the cathode shape given the conditions that temperature and electrolyte flow are kept constant. Electric field distribution and electrolyte flow patterns inside the cavity are simulated via Poisson–Superfish and Solidworks respectively. With the optimal cathode shape, BEP shows a much faster polishing rate of ∼2.5 μm/min and is able to produce a smoother surface finish in the treatments of single cell cavities in comparison with EP.

  5. Effect of electrothermal annealing on the transformation behavior of TiNi shape memory alloy and two-way shape memory spring actuated by direct electrical current

    International Nuclear Information System (INIS)

    Wang, Z.G.; Zu, X.T.; Feng, X.D.; Zhu, S.; Deng, J.; Wang, L.M.

    2004-01-01

    In this work, the effect of electrothermal annealing on the transformation characterization of TiNi shape memory alloy and the electrothermal actuating characteristics of a two-way shape memory effect (TWSME) extension spring were investigated with direct electrical current. The results showed that with increasing direct electrical current density, the B2→R-phase transformation shifts to a lower temperature and R-phase→B19' shifts to a higher temperature in the cooling process. When annealing electrical current density reached 12.2 A/mm 2 , the R-phase disappeared and austenite transformed into martensite directly. The electrothermal annealing was an effective method of heat treatment in a selected part of shape memory alloy device. The electrothermal actuating characteristics of a TWSME spring showed that the time response and the maximum elongation greatly depended on the magnitude of the electrical current

  6. Rotational effects of polymeric fluids on shape of filaments in melt extruded net structures

    CSIR Research Space (South Africa)

    Rawal, A

    2006-01-01

    Full Text Available -circular geometries on their peripheries and the filaments are produced when the slots in disk and annulus are offset from each other. The effect of die rotation on the shape of filament is investigated by analysing the polymer flow inside the complex die slots...

  7. The effect of box shape on the dynamic properties of proteins simulated under periodic boundary conditions

    NARCIS (Netherlands)

    Wassenaar, T.A.; Mark, A.E.

    The effect of the box shape on the dynamic behavior of proteins simulated under periodic boundary conditions is evaluated. In particular, the influence of simulation boxes defined by the near-densest lattice packing (NDLP) in conjunction with rotational constraints is compared to that of standard

  8. The Effect of the Shape of Atomic Potential on the Diffraction Pattern ...

    African Journals Online (AJOL)

    We have simulated the diffraction patterns of both periodic and quasiperiodic monatomic chains using the code Laue (written by Silsbee and Drager) and investigated the effects of the shape of the atomic potential. Three fundamental differences between the diffraction patterns of periodic and quasiperiodic monatomic chain ...

  9. 2007 Effect of Changes in Layout Shape on Unit Construction Cost

    African Journals Online (AJOL)

    ezra

    The shape of a building layout is the spatial attribute that defines the outline of the building. ... The results of this study indicate that perimeter-to-floor ratio, unit construction ... Design variables have been defined as the .... The objective of this paper is to explore the effect ... preparation of cost estimate, changing of design.

  10. Effect of Changes in Layout Shape on Unit Construction Cost of ...

    African Journals Online (AJOL)

    The conclusions of previous studies on the cost implication of building shape have been premised on the knowledge of building morphological and geometrical characteristics, and have lacked empirical authentication. This study used empirical data to investigate the effect of layout narrowness and complexity (irregularity) ...

  11. Effect of Using Logo on Pupils' Learning in Two-Dimensional Shapes

    Science.gov (United States)

    Yi, Boo Jia; Eu, Leong Kwan

    2016-01-01

    The integration of technology in mathematics instruction is an important step in the 21st century learning style. At the primary level, some studies have explored how technology could help in mathematics learning. The purpose of this study is to determine the effect of using Logo on pupils' learning of the properties of two-dimensional shapes. A…

  12. Perspective on "The effect of shape on the interaction of colloidal particles"

    NARCIS (Netherlands)

    Frenkel, D.

    2000-01-01

    Onsager's paper on the effect of shape on the interaction of colloidal particles is seminal in many ways. I shall focus on two aspects: it is (to my knowledge) the earliest classical density functional theory, and it demonstrates the possibility of ordering transitions driven by entropy

  13. Shape memory effect and microstructures of sputter-deposited Cu-Al-Ni films

    International Nuclear Information System (INIS)

    Minemura, T.; Andoh, H.; Kita, Y.; Ikuta, I.

    1985-01-01

    The shape memory effect has been found in many alloy systems which exhibit a thermoelastic martensite transformation. Cu-Al-Ni alloys exhibit an excellent shape memory effect in single crystalline states, but they have not yet been commercially used due to their brittle fracture along the grain boundaries in polycrystalline states. This letter reports the shape memory effect and microstructures of the sputter-deposited Cu-Al-Ni films. Cu-14%Al-4%Ni alloy ingot was prepared. A target for sputter deposition was cut from the ingot. Aluminium foils (20 μm thick) were used for the substrates of sputter deposition. The microstructures and crystal structures of the films were investigated by transmission electron microscopy (TEM) and X-ray diffraction using CuKα radiation, respectively. The effect of the sputtering conditions such as substrate temperature, partial pressure of argon gas, and the sputtering power on the structures of sputter-deposited Cu-14%Al-4%Ni films were investigated by X-ray diffraction. Results are shown and discussed. Photographs demonstrate shape memory behaviour of Cu-14%Al-4%Ni films sputter-deposited on aluminium foils from (a) liquid nitrogen temperature to (d) room temperature. (author)

  14. Effect of alloying elements on the shape memory properties of ductile Cu-Al-Mn alloys

    International Nuclear Information System (INIS)

    Sutou, Y.; Kainuma, R.; Ishida, K.

    1999-01-01

    The effect of alloying elements on the M s temperature, ductility and the shape memory properties of Cu-Al-Mn ductile shape memory (SM) alloys was investigated by differential scanning calorimetry, cold-rolling and tensile test techniques. It was found that the addition of Au, Si and Zn to the Cu 73 -Al 17 -Mn 10 alloy stabilized the martensite (6M) phase increasing the M s temperature, while the addition of Ag, Co, Cr, Fe, Ni, Sn and Ti decreased the stability of the martensite phase, decreasing the M s temperature. The SM properties were improved by the addition of Co, Ni, Cr and Ti. (orig.)

  15. Influence of changing in sign plastic deformation on shape memory effects in titanium nickelide

    International Nuclear Information System (INIS)

    Belyaev, S.P.; Volkov, A.E.; Evard, M.E.; Leskina, M.L.

    2005-01-01

    The effects of shape memory, martensite transformation plasticity, and two-way shape memory in titanium nickelide (TiNi) prestrained in an alternating-sign mode have been studied. It was ascertained that the reversible deformation and the temperature-dependent deformation kinetics in the temperature interval of martensite transformation were independent of the degree of prestraining. Based on the results the conclusion is made that an increase in the density of dislocations does not influence essentially the deformation behavior of titanium nickelide in the vicinity of the martensite transformation. The results of computer simulation based on the structural analytical theory are in a satisfactory agreement with the experiment [ru

  16. Two-way shape memory effect induced by repetitive compressive loading cycles

    International Nuclear Information System (INIS)

    Kim, Hyun-Chul; Yoo, Young-Ik; Lee, Jung-Ju

    2009-01-01

    The NiTi alloy can be trained by repetitive loading or heating cycles. As a result of the training, a two-way shape memory effect (TWSME) can be induced. Considerable research has been reported regarding the TWSME trained by tensile loading. However, the TWSME trained by compressive loading has not been investigated nearly as much. In this paper, the TWSME is induced by compressive loading cycles and the two-way shape memory strain is evaluated by using two types of specimen: a solid cylinder type and a tube type. The TWSME trained by compressive loading is different from that trained by tensile loading owing to the severe tension/compression asymmetry as described in previous research. After repetitive compressive loading cycles, strain variation upon cooling is observed, and this result proves that the TWSME is induced by compressive loading cycles. By performing compressive loading cycles, plastic deformation in NiTi alloy occurs more than for tensile loading cycles, which brings about the appearance of TWSME. It can be said that the TWSME is induced by compressive loading cycles more easily. The two-way shape memory strain increases linearly as the maximum strain of compressive loading cycles increases, regardless of the shape and the size of the NiTi alloy; this two-way shape memory strain then shows a tendency towards saturation after some repeated cycles

  17. Pressure Enhancement in Confined Fluids: Effect of Molecular Shape and Fluid-Wall Interactions.

    Science.gov (United States)

    Srivastava, Deepti; Santiso, Erik E; Gubbins, Keith E

    2017-10-24

    Recently, several experimental and simulation studies have found that phenomena that normally occur at extremely high pressures in a bulk phase can occur in nanophases confined within porous materials at much lower bulk phase pressures, thus providing an alternative route to study high-pressure phenomena. In this work, we examine the effect on the tangential pressure of varying the molecular shape, strength of the fluid-wall interactions, and pore width, for carbon slit-shaped pores. We find that, for multisite molecules, the presence of additional rotational degrees of freedom leads to unique changes in the shape of the tangential pressure profile, especially in larger pores. We show that, due to the direct relationship between the molecular density and the fluid-wall interactions, the latter have a large impact on the pressure tensor. The molecular shape and pore size have a notable impact on the layering of molecules in the pore, greatly influencing both the shape and scale of the tangential pressure profile.

  18. Lattice density functional theory investigation of pore shape effects. I. Adsorption in single nonperiodic pores.

    Science.gov (United States)

    Malanoski, A P; van Swol, Frank

    2002-10-01

    A fully explicit in three dimensions lattice density functional theory is used to investigate adsorption in single nonperiodic pores. The effect of varying pore shape from the slits and cylinders that are normally simulated was our primary interest. A secondary concern was the results for pores with very large diameters. The shapes investigated were square pores with or without surface roughness, cylinders, right triangle pores, and trapezoidal pores. It was found that pores with very similar shape factors gave similar results but that the introduction of acute angled corners or very large side ratio lengths in rectangular pores gave results that were significantly different. Further, a rectangular pore going towards the limit of infinite side ratio does not approach the results of a slit pore. In all of these cases, the importance of features that are present for only a small portion of the pore is demonstrated.

  19. Shape and 'gap' effects on the behavior of variably confined concrete

    International Nuclear Information System (INIS)

    Harries, Kent A.; Carey, Shawn A.

    2003-01-01

    Factors affecting the behavior of variably confined concrete are presented. The effect of debonding the fiber-reinforced polymer (FRP) jacket to the concrete substrate and providing a gap between the concrete and confining jacket is investigated. A second parameter--the shape of the cross section--is also investigated. An experimental program involving the compression testing of standard cylinders and similarly sized square specimens having external FRP jackets providing passive confinement is presented. Factors affecting jacket efficiency and the appropriateness of factors accounting for specimen shape are determined experimentally and discussed. The provision of a gap affected the axial stress at which the confining jacket was engaged, resulting in a reduced maximum attainable concrete strength. The jacket efficiency was not affected by the provision of the gap. The shape of the specimens was observed to affect the level of confinement generated. Square specimens exhibit lower confinement levels than circular specimens having the same jacket

  20. Computational and experimental study of effects of sediment shape on erosion of hydraulic turbines

    International Nuclear Information System (INIS)

    Poudel, L; Thapa, B; Shrestha, B P; Thapa, B S; Shrestha, K P; Shrestha, N K

    2012-01-01

    Hard particles as Quartz and Feldspar are present in large amount in most of the rivers across the Himalayan basins. In run-off-river hydro power plants these particles find way to turbine and cause its components to erode. Loss of turbine material due to the erosion and subsequent change in flow pattern induce several operational and maintenance problems in the power plants. Reduction in overall efficiency, vibrations and reduced life of turbine components are the major effects of sediment erosion of hydraulic turbines. Sediment erosion of hydraulic turbines is a complex phenomenon and depends upon several factors. One of the most influencing parameter is the characteristics of sediment particles. Quantity of sediment particles, which are harder than the turbine material, is one of the bases to indicate erosion potential of a particular site. Research findings have indicated that shape and size of the hard particles together with velocity of impact play a major role to decide the mode and rate of erosion in turbine components. It is not a common practice in Himalayan basins to conduct a detail study of sediment characteristics as a part of feasibility study for hydropower projects. Lack of scientifically verified procedures and guidelines to conduct the sediment analysis to estimate its erosion potential is one of the reasons to overlook this important part of feasibility study. Present study has been conducted by implementing computational tools to characterize the sediment particles with respect to their shape and size. Experimental studies have also been done to analyze the effects of different combinations of shape and size of hard particles on turbine material. Efforts have also been given to develop standard procedures to conduct similar study to compare erosion potential between different hydropower sites. Digital image processing software and sieve analyzer have been utilized to extract shape and size of sediment particles from the erosion sensitive power

  1. Effects of target shape and reflection on laser radar cross sections.

    Science.gov (United States)

    Steinvall, O

    2000-08-20

    Laser radar cross sections have been evaluated for a number of ideal targets such as cones, spheres, paraboloids, and cylinders by use of different reflection characteristics. The time-independent cross section is the ratio of the cross section of one of these forms to that of a plate with the same maximum radius. The time-dependent laser radar cross section involves the impulse response from the object shape multiplied by the beam's transverse profile and the surface bidirectional reflection distribution function. It can be clearly seen that knowledge of the combined effect of object shape and reflection characteristics is important for determining the shape and the magnitude of the laser radar return. The results of this study are of interest for many laser radar applications such as ranging, three-dimensional imaging-modeling, tracking, antisensor lasers, and target recognition.

  2. Exploring laterality and memory effects in the haptic discrimination of verbal and non-verbal shapes.

    Science.gov (United States)

    Stoycheva, Polina; Tiippana, Kaisa

    2018-03-14

    The brain's left hemisphere often displays advantages in processing verbal information, while the right hemisphere favours processing non-verbal information. In the haptic domain due to contra-lateral innervations, this functional lateralization is reflected in a hand advantage during certain functions. Findings regarding the hand-hemisphere advantage for haptic information remain contradictory, however. This study addressed these laterality effects and their interaction with memory retention times in the haptic modality. Participants performed haptic discrimination of letters, geometric shapes and nonsense shapes at memory retention times of 5, 15 and 30 s with the left and right hand separately, and we measured the discriminability index d'. The d' values were significantly higher for letters and geometric shapes than for nonsense shapes. This might result from dual coding (naming + spatial) or/and from a low stimulus complexity. There was no stimulus-specific laterality effect. However, we found a time-dependent laterality effect, which revealed that the performance of the left hand-right hemisphere was sustained up to 15 s, while the performance of the right-hand-left hemisphere decreased progressively throughout all retention times. This suggests that haptic memory traces are more robust to decay when they are processed by the left hand-right hemisphere.

  3. Observation of the two-way shape memory effect in an atomistic model of martensitic transformation

    Directory of Open Access Journals (Sweden)

    Eduardo Jagla

    2017-05-01

    Full Text Available We study a system of classical particles in two dimensions interacting through an isotropic pair potential that displays a martensitic phase transition between a triangular and a rhomboidal structure upon the change of a single parameter. Previously it was shown that this potential is able to reproduce the shape memory effect and super-elasticity, among other well known features of the phenomenology of martensites. Here we extend those previous studies and describe the development of the more subtle two-way shape memory effect. We show that in a poly-crystalline sample, the effect is mostly due to the existence of retained martensite within the austenite phase. We also study the case of a single crystal sample where the effect is associated to particular orientations of the dislocations, either induced by training or by an ad hoc construction of a starting sample.

  4. Water-Blown Polyurethane Foams Showing a Reversible Shape-Memory Effect

    Directory of Open Access Journals (Sweden)

    Elena Zharinova

    2016-11-01

    Full Text Available Water-blown polyurethane (PU foams are of enormous technological interest as they are widely applied in various fields, i.e., consumer goods, medicine, automotive or aerospace industries. The discovery of the one-way shape-memory effect in PU foams provided a fresh impetus for extensive investigations on porous polymeric actuators over the past decades. High expansion ratios during the shape-recovery are of special interest when big volume changes are required, for example to fill an aneurysm during micro-invasive surgery or save space during transportation. However, the need to program the foams before each operation cycle could be a drawback impeding the entry of shape-memory polymeric (SMP foams to our daily life. Here, we showed that a reversible shape-memory effect (rSME is achievable for polyurethane water-blown semicrystalline foams. We selected commercially available crystallizable poly(ε-caprolactone-diols of different molecular weight for foams synthesis, followed by investigations of morphology, thermal, thermomechanical and shape-memory properties of obtained compositions. Densities of synthesized foams varied from 110 to 180 kg∙m−3, while peak melting temperatures were composition-dependent and changed from 36 to 47 °C, while the melting temperature interval was around 15 K. All semicrystalline foams exhibited excellent one-way SME with shape-fixity ratios slightly above 100% and shape-recovery ratios from the second cycle of 99%. The composition with broad distribution of molecular weights of poly(ε-caprolactone-diols exhibited an rSME of about 12% upon cyclic heating and cooling from Tlow = 10 °C and Thigh = 47 °C. We anticipate that our experimental study opens a field of systematic investigation of rSMEs in porous polymeric materials on macro and micro scale and extend the application of water-blown polyurethane foams to, e.g., protective covers with zero thermal expansion or even cushions adjustable to a certain body

  5. Periodic Cellular Structure Technology for Shape Memory Alloys

    Science.gov (United States)

    Chen, Edward Y.

    2015-01-01

    Shape memory alloys are being considered for a wide variety of adaptive components for engine and airframe applications because they can undergo large amounts of strain and then revert to their original shape upon heating or unloading. Transition45 Technologies, Inc., has developed an innovative periodic cellular structure (PCS) technology for shape memory alloys that enables fabrication of complex bulk configurations, such as lattice block structures. These innovative structures are manufactured using an advanced reactive metal casting technology that offers a relatively low cost and established approach for constructing near-net shape aerospace components. Transition45 is continuing to characterize these structures to determine how best to design a PCS to better exploit the use of shape memory alloys in aerospace applications.

  6. Effect of power shape on energy extraction from microbial fuel cell

    Science.gov (United States)

    Alaraj, Muhannad; Feng, Shuo; Roane, Timberley M.; Park, Jae-Do

    2017-10-01

    Microbial fuel cells (MFCs) generate renewable energy in the form of direct current (DC) power. Harvesting energy from MFCs started with passive components such as resistors and capacitors, then charge pumps were introduced with some more advantages. Power electronics converters were later preferred due to their higher efficiency and controllability; however, they introduce high frequency current ripple due to their high frequency switching. In this paper, the effect of shape of power extraction on MFC performance was investigated using three types of current shapes: continuous, square-wave, and triangular-wave. Simultaneously, chemical parameters, such as pH, dissolved oxygen, electrical conductivity, and redox potential, in the anode chamber were monitored to see how these parameters change with the shape of the electrical power extraction. Results showed that the shape of the extracted current did not have a substantial effect on the MFC life span, output power, and energy extraction, nor on the chemical parameters. The outcome of this study provided insight for the electrical impact by power electronics converters on some microbial and chemical aspects of an MFC system.

  7. Analytical model for shape anisotropy in thin-film nanostructured arrays: Interaction effects

    International Nuclear Information System (INIS)

    Alvarez-Sanchez, R.; Costa-Kraemer, J.L.; Briones, F.

    2006-01-01

    When reducing the size of array elements and interelement separations to the nanoscale, long-range magnetostatic interactions become important. A methodology that extends the study of conventional single-element magnetostatics is presented, adding the effect of stacking nanoelements into close proximity in arrays and the consequent interaction effects. This would be very time consuming to model by micromagnetic simulations that are also very vulnerable to artifacts due to cell or boundary condition selection. The proposed method considers an analytical expression valid for short interelement separations and not very costly to evaluate by computational means. This approach allows the quantitative study of shape anisotropy in non-square-shaped arrays. It is also shown how it can be used to find anisotropy compensation conditions, where an anisotropy due to a magnetic element shape can be compensated by the shape anisotropy due to the array. The obtained results can be used to establish a criterion for the minimum number of elements to be considered for a micromagnetic simulation of an array to be realistic depending on the element size and separation

  8. Intraoral Temperature Triggered Shape-Memory Effect and Sealing Capability of A Transpolyisoprene-Based Polymer

    Directory of Open Access Journals (Sweden)

    Gakuji Tsukada

    2015-11-01

    Full Text Available In dentistry, pure gutta-percha (trans-1,4-polyisoprene (TPI is widely used as a main component of root canal filling materials. TPI has an interesting shape memory formed through cross-linking, and this characteristic is expected to be very effective for development of novel dental treatments; in particular, modification of the shape recovery temperature to the intraoral temperature (37 °C will enhance the applicability of the shape-memory effect of TPI in root canal filling. In this study, trial test specimens consisting of varying proportions of TPI, cis-polyisoprene, zinc oxide, stearic acid, sulfur and dicumyl peroxide were prepared and the temperature dependence of their shape recovery, recovery stress and relaxation modulus were measured. Additionally, their sealing abilities were tested using glass tubing and a bovine incisor. As the ratio of cross-linking agent in the specimens increased, a decrease in recovery temperature and an increase in recovery stress and recovery speed were observed. In addition, the test specimen containing the highest concentration of cross-linking agent showed superior sealing ability under a thermal stimulus of 37 °C in both sealing ability tests.

  9. Effect of Al alloying on the martensitic temperature in Ti-Ta shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, Alberto; Rogal, Jutta; Drautz, Ralf [Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universitaet Bochum (Germany)

    2017-07-01

    Ti-Ta-based alloys are promising candidates as high temperature shape memory alloys (HTSMAs) for actuators and superelastic applications. The shape memory mechanism involves a martensitic transformation between the low-temperature α'' phase (orthorhombic) and the high-temperature β phase (body-centered cubic). In order to prevent the degradation of the shape memory effect, Ti-Ta needs to be alloyed with further elements. However, this often reduces the martensitic temperature M{sub s}, which is usually strongly composition dependent. The aim of this work is to analyze how the addition of a third element to Ti-Ta alloys affects M{sub s} by means of electronic structure calculations. In particular, it will be investigated how alloying Al to Ti-Ta alters the relative stability of the α'' and β phases. This understanding will help to identify new alloy compositions featuring both a stable shape memory effect and elevated transformation temperatures.

  10. Effect of surface oxidation on thermomechanical behavior of NiTi shape memory alloy wire

    Science.gov (United States)

    Ng, Ching Wei; Mahmud, Abdus Samad

    2017-12-01

    Nickel titanium (NiTi) alloy is a unique alloy that exhibits special behavior that recovers fully its shape after being deformed to beyond elastic region. However, this alloy is sensitive to any changes of its composition and introduction of inclusion in its matrix. Heat treatment of NiTi shape memory alloy to above 600 °C leads to the formation of the titanium oxide (TiO2) layer. Titanium oxide is a ceramic material that does not exhibit shape memory behaviors and possess different mechanical properties than that of NiTi alloy, thus disturbs the shape memory behavior of the alloy. In this work, the effect of formation of TiO2 surface oxide layer towards the thermal phase transformation and stress-induced deformation behaviors of the NiTi alloy were studied. The NiTi wire with composition of Ti-50.6 at% Ni was subjected to thermal oxidation at 600 °C to 900 °C for 30 and 60 minutes. The formation of the surface oxide layers was characterized by using the Scanning Electron Microscope (SEM). The effect of surface oxide layers with different thickness towards the thermal phase transformation behavior was studied by using the Differential Scanning Calorimeter (DSC). The effect of surface oxidation towards the stress-induced deformation behavior was studied through the tensile deformation test. The stress-induced deformation behavior and the shape memory recovery of the NiTi wire under tensile deformation were found to be affected marginally by the formation of thick TiO2 layer.

  11. Effects of Ag Nanocubes with Different Corner Shape on the Absorption Enhancement in Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Feng Shan

    2014-01-01

    Full Text Available The effects of corner shape of silver (Ag nanocubes (NCs on optical absorptions of organic solar cells (OSCs are theoretically investigated by finite element method (FEM calculations. The absorption of sun light in the active layer is calculated. Significant absorption enhancements have been demonstrated in metallic region with different shapes of Ag NCs, among them corner radius (R is zero result in the best light absorption performance of up to 55% enhancement with respect to bare OSCs. The origins of increased absorption are believed to be the effects of the huge electric field enhancement and increased scattering upon the excitation of localized surface plasmon resonance (LSPR. Apart from using R=0, we show that R=3, 6, and 11.29 of Ag NCs in metallic region of active layer may also result in the maximum comparable absorption enhancement of 49%, 41%, and 28%, respectively. In addition, a significant effect of the period of NCs is observed.

  12. A new intratracheal stent made from nitinol, an alloy with "shape memory effect".

    Science.gov (United States)

    Vinograd, I; Klin, B; Brosh, T; Weinberg, M; Flomenblit, Y; Nevo, Z

    1994-05-01

    Temporary or permanent tracheal splinting in pediatric patients may be indicated in tracheomalacia or bronchomalacia, repair of congenital tracheal stenosis, and after tracheal resection. This study presents the results of the development of a new intraluminal airway stent made from titanium alloy, a metal with "shape memory effect". At low temperatures (martensitic state) the titanium alloy stent can be fashioned into a specific shape; then when heated to a higher temperature (austenitic state) the stent alters its shape, only to regain its original shape when recooled to the lower temperature. The stent, connected to a small electric power supply, was introduced into 20 young rabbits with the use of a 2.5 cm rigid bronchoscope. After implantation in the martensitic state the stent was warmed to 40 degrees C, the austenitic state, by an electric current of 1.5 to 3 ampere for 1 to 2 seconds. After a period of 8 to 10 weeks the stent was removed (in its martensitic state) through the same-sized bronchoscope after being cooled with 3 to 4 ml of 80% alcohol solution at 6 degrees C. No signs of airway obstruction developed in any of the animals after implantation or extraction of the stent. The biomechanical properties of the trachea, as shown by strain measurements with the use of incremental forces, showed significant differences between the stented and unstented segments (p stent adequately fulfilled the requirements of a temporary intraluminal airway splint, and because of its unique feature of shape memory effect the stent could be inserted, fixed, and removed easily, even in very small airways.

  13. Boiling transition phenomenon in BWR fuel assemblies effect of fuel spacer shape on critical power

    International Nuclear Information System (INIS)

    Yamamoto, Yasushi; Morooka, Shin-ichi; Mitsutake, Toru; Yokobori, Seiichi; Kimura, Jiro.

    1996-01-01

    A thorough understanding of the thermal-hydraulic phenomena near fuel spacer is necessary for the accurate prediction of the critical power of BWR fuel assemblies, and is thus essential for effective developments of a new BWR fuel assembly. The main purpose of this study is to develop an accurate method for predicting the effect of spacer shapes on critical power. Tests have been conducted under actual BWR operating conditions, using an annulus flow channel consisting of a heated rod and circular-tube channel, and BWR simulated 4x4 rod bundles with heater rods unheated just upsteam of spacer. The effect of spacer shapes on critical power was predicted analytically based on the droplet deposition rate estimation. The droplet deposition rate for different spacer shapes was calculated using a single-phase flow model. The prediction results were compared with the test results for the annulus flow channel using ring-type spacers. Analytical results of critical power agreed with measured critical power from point of the effects of changes in the rod-spacer clearance and the spacer thickness on critical power. (author)

  14. Effect of laser pulse shaping parameters on the fidelity of quantum logic gates.

    Science.gov (United States)

    Zaari, Ryan R; Brown, Alex

    2012-09-14

    The effect of varying parameters specific to laser pulse shaping instruments on resulting fidelities for the ACNOT(1), NOT(2), and Hadamard(2) quantum logic gates are studied for the diatomic molecule (12)C(16)O. These parameters include varying the frequency resolution, adjusting the number of frequency components and also varying the amplitude and phase at each frequency component. A time domain analytic form of the original discretized frequency domain laser pulse function is derived, providing a useful means to infer the resulting pulse shape through variations to the aforementioned parameters. We show that amplitude variation at each frequency component is a crucial requirement for optimal laser pulse shaping, whereas phase variation provides minimal contribution. We also show that high fidelity laser pulses are dependent upon the frequency resolution and increasing the number of frequency components provides only a small incremental improvement to quantum gate fidelity. Analysis through use of the pulse area theorem confirms the resulting population dynamics for one or two frequency high fidelity laser pulses and implies similar dynamics for more complex laser pulse shapes. The ability to produce high fidelity laser pulses that provide both population control and global phase alignment is attributed greatly to the natural evolution phase alignment of the qubits involved within the quantum logic gate operation.

  15. Suppressive and enhancing effects in early visual cortex during illusory shape perception: A comment on.

    Science.gov (United States)

    Moors, Pieter

    2015-01-01

    In a recent functional magnetic resonance imaging study, Kok and de Lange (2014) observed that BOLD activity for a Kanizsa illusory shape stimulus, in which pacmen-like inducers elicit an illusory shape percept, was either enhanced or suppressed relative to a nonillusory control configuration depending on whether the spatial profile of BOLD activity in early visual cortex was related to the illusory shape or the inducers, respectively. The authors argued that these findings fit well with the predictive coding framework, because top-down predictions related to the illusory shape are not met with bottom-up sensory input and hence the feedforward error signal is enhanced. Conversely, for the inducing elements, there is a match between top-down predictions and input, leading to a decrease in error. Rather than invoking predictive coding as the explanatory framework, the suppressive effect related to the inducers might be caused by neural adaptation to perceptually stable input due to the trial sequence used in the experiment.

  16. Effect of gas expansion on the front shape of a Taylor bubble: an experimental contribution

    Directory of Open Access Journals (Sweden)

    Santos Laura

    2014-03-01

    Full Text Available An experimental study where an individual Taylor bubble rises through water with different bubble volume expansion rates is presented with the (front bubble shape determination as main objective. A combination of two techniques, Particle Image Velocimetry (PIV and Pulsed Shadowgraphy (PS, was used to collect images for further treatment in order to characterize the liquid flow pattern in front of the bubble and the bubble shape. Processing the images acquired with pulsed illumination from behind the bubble it was possible to define with precision the bubble shape at different stages when it was expanding. The operation conditions used allowed a wide range of volume expansion rates (0 to 28.5 × 10-6 m3/s with a significant effect on the Taylor bubble velocity; increases in bubble velocity up to 21% were observed relatively to constant volume system condition. Nevertheless, it seems that the front shape of Taylor bubbles does not change significantly with the upward liquid flow rates induced by gas expansion, at least for the volume expansion rates used in the experiments.

  17. Precipitation-hardening stainless steels with a shape-memory effect

    Science.gov (United States)

    Sagaradze, V. V.; Afanasiev, S. V.; Volkova, E. G.; Zavalishin, V. A.

    2016-02-01

    The possibility of obtaining the shape-memory effect as a result of the γ → ɛ → γ transformations in aging stainless steels strengthened by VC carbides has been investigated. Regimes are given for strengthening aging (at 650 and 720°C) for stainless steels that predominantly contain (in wt %) 0.06-0.45C, 1-2V, 2-5Si, 9 and 13-14Cr. The values of reversible deformation e (amount of shape-memory effect) determined after heating to 400°C in samples preliminarily deformed to 3.5-4% vary from 0.15 to 2.7%, depending on the composition of the steels and regimes of stabilizing and destabilizing aging.

  18. Effect of particle shape on thermal conductivity of Al2O3 nanofluids

    International Nuclear Information System (INIS)

    Kim, Hyun Jin; Lee, Seung Hyun; Kwon, Hey Lim; Jang, Seok Pil; Lim, Hyung Mi

    2009-01-01

    In this paper, thermal conductivities of water-based Al 2 O 3 nanofluids with brick, blade, platelet and rod type nanoparticle are measured by transient hot wire method to investigate the effect of nanoparticle shape on thermal conductivity. Water-based Al 2 O 3 nanofluids are prepared by two-step method and that of volume fraction is 3%. Temperature dependency of thermal conductivity of water-based Al 2 O 3 nanofluids is also studied by measuring of thermal conductivity from 22 .deg. C to 42 .deg. C. TEM micrograph, zeta potential and BET are measured to investigate suspension and disperse stability of water-based Al 2 O 3 nanofluids. Furthermore, Experimental results are compared with theoretical models such as Hamilton-Crosser model considering the shape effects on thermal conductivity.

  19. Effects of source shape on the numerical aperture factor with a geometrical-optics model.

    Science.gov (United States)

    Wan, Der-Shen; Schmit, Joanna; Novak, Erik

    2004-04-01

    We study the effects of an extended light source on the calibration of an interference microscope, also referred to as an optical profiler. Theoretical and experimental numerical aperture (NA) factors for circular and linear light sources along with collimated laser illumination demonstrate that the shape of the light source or effective aperture cone is critical for a correct NA factor calculation. In practice, more-accurate results for the NA factor are obtained when a linear approximation to the filament light source shape is used in a geometric model. We show that previously measured and derived NA factors show some discrepancies because a circular rather than linear approximation to the filament source was used in the modeling.

  20. Effect of radiation on preservation of convenient dish 'bowl-shape packed pig elbow'

    International Nuclear Information System (INIS)

    Wang Keqin; Chen Jingping; Li Wenge; Peng Weizheng

    2005-01-01

    The suitable parameters for radiation processing were investiqated by analyzing the microload of material and product, and radiation effect on the preservation of convenient dish 'bowl-shape packed pig elbow'. The results showed the store period of the product could be extended 2-6 month by 4.0-6.0 kGy radiation at different storage temperature. The sensory, physical and chemical index of the products met the requirement of relevant national standard of food hygiene. (authors)

  1. EFFECT OF PLASMA CUTTING PARAMETERS UPON SHAPES OF BEARING CURVE OF C45 STEEL SURFACE

    Directory of Open Access Journals (Sweden)

    Agnieszka Skoczylas

    2015-08-01

    Full Text Available The article presents the results of studies on the effect of plasma cutting technological parameters upon the shape of bearing curves and the parameters of the curve. The topography of surface formed by plasma cutting were analyzed. For measuring surface roughness and determining the bearing curve the appliance T8000 RC120 – 400 by Hommel-Etamic was used together with software.

  2. Shaping effective communication skills and therapeutic relationships at work: the foundation of collaboration.

    Science.gov (United States)

    Grover, Susan M

    2005-04-01

    Effective communication is essential to practice and can result in improved interpersonal relationships at the workplace. Effective communication is shaped by basic techniques such as open-ended questions, listening, empathy, and assertiveness. However, the relationship between effective communication and successful interpersonal relationships is affected by intervening variables. The variables of gender, generation, context, collegiality, cooperation, self-disclosure, and reciprocity can impede or enhance the outcome of quality communication. It is essential for occupational health nurses to qualitatively assess the degree to which each of these concepts affects communication and, in turn, relationships at work.

  3. Entropic effects, shape, and size of mixed micelles formed by copolymers with complex architectures

    Science.gov (United States)

    Kalogirou, Andreas; Gergidis, Leonidas N.; Moultos, Othonas; Vlahos, Costas

    2015-11-01

    The entropic effects in the comicellization behavior of amphiphilic A B copolymers differing in the chain size of solvophilic A parts were studied by means of molecular dynamics simulations. In particular, mixtures of miktoarm star copolymers differing in the molecular weight of solvophilic arms were investigated. We found that the critical micelle concentration values show a positive deviation from the analytical predictions of the molecular theory of comicellization for chemically identical copolymers. This can be attributed to the effective interactions between copolymers originated from the arm size asymmetry. The effective interactions induce a very small decrease in the aggregation number of preferential micelles triggering the nonrandom mixing between the solvophilic moieties in the corona. Additionally, in order to specify how the chain architecture affects the size distribution and the shape of mixed micelles we studied star-shaped, H-shaped, and homo-linked-rings-linear mixtures. In the first case the individual constituents form micelles with preferential and wide aggregation numbers and in the latter case the individual constituents form wormlike and spherical micelles.

  4. Effect of Lidocaine and Epinephrine on Human Erythrocyte Shape and Vesiculability of Blood Cells

    Directory of Open Access Journals (Sweden)

    Tanja Slokar

    2015-01-01

    Full Text Available The effect of local anesthetic composed of lidocaine and epinephrine on vesiculability of blood cells and erythrocyte shape was studied. Whole blood and plasma were incubated with lidocaine/epinephrine. Extracellular vesicles were isolated by centrifugation and washing and counted by flow cytometry. Lidocaine/epinephrine and each component alone were added to diluted blood. Shape changes were recorded by micrographs. An ensemble of captured frames was analyzed for populations of discocytes, echinocytes, and stomatocytes by using statistical methods. Incubation of whole blood and blood plasma with lidocaine/epinephrine considerably increased concentration of extracellular vesicles in isolates (for an average factor 3.4 in blood and 2.8 in plasma. Lidocaine/epinephrine caused change of erythrocyte shape from mainly discocytic to mainly stomatocytic (higher than 50%. Lidocaine alone had even stronger stomatocytic effect (the percent of stomatocytes was higher than 95% while epinephrine had echinocytic effect (the percent of echinocytes was higher than 80%. The differences were highly statistically significant p<10-8 with statistical power P=1. Lidocaine/epinephrine induced regions of highly anisotropically curved regions indicating that lidocaine and epinephrine interact with erythrocyte membrane. It was concluded that lidocaine/epinephrine interacts with cell membranes and increases vesiculability of blood cells in vitro.

  5. Effect of Combustion-chamber Shape on the Performance of a Prechamber Compression-ignition Engine

    Science.gov (United States)

    Moore, C S; Collins, J H , Jr

    1934-01-01

    The effect on engine performance of variations in the shape of the prechamber, the shape and direction of the connecting passage, the chamber volume using a tangential passage, the injection system, and the direction od the fuel spray in the chamber was investigated using a 5 by 7 inch single-cylinder compression-ignition engine. The results show that the performance of this engine can be considerably improved by selecting the best combination of variables and incorporating them in a single design. The best combination as determined from these tests consisted of a disk-shaped chamber connected to the cylinder by means of a flared tangential passage. The fuel was injected through a single-orifice nozzle directed normal to the air swirl and in the same plane. At an engine speed of 1,500 r.p.m. and with the theoretical fuel quantity for no excess air, the engine developed a brake mean effective pressure of 115 pounds per square inch with a fuel consumption of 0.49 pound per brake horsepower-hour and an explosion pressure of 820 pounds per square inch. A brake mean effective pressure of 100 pounds per square inch with a brake-fuel consumption of 0.44 pound per horsepower-hour at 1,500 r.p.m. was obtained.

  6. Effects of social adversity and HIV on subcortical shape and neurocognitive function.

    Science.gov (United States)

    Thames, April D; Kuhn, Taylor P; Mahmood, Zanjbeel; Bilder, Robert M; Williamson, Timothy J; Singer, Elyse J; Arentoft, Alyssa

    2018-02-01

    The purpose of the current study was to examine the independent and interactive effects of social adversity (SA) and HIV infection on subcortical shape alterations and cognitive functions. Participants included HIV+ (n = 70) and HIV- (n = 23) individuals who underwent MRI, neurocognitive and clinical assessment, in addition to completing questionnaires from which responses were used to create an SA score. Bilateral amygdalae and hippocampi were extracted from T1-weighted images. Parametric statistical analyses were used to compare the radial distance of the structure surface to a median curve to determine the presence of localized shape differences as a function of HIV, SA and their interaction. Next, multiple regression was used to examine the interactive association between HIV and SA with cognitive performance data. An HIV*SA interactive effect was found on the shape of the right amygdala and left hippocampus. Specifically, HIV-infected participants (but not HIV-uninfected controls) who evidenced higher levels of SA displayed an inward deformation of the surface consistent with reduced volume of these structures. We found interactive effects of HIV and SA on learning/memory performance. These results suggest that HIV+ individuals may be more vulnerable to neurological and cognitive changes in the hippocampus and amygdala as a function of SA than HIV- individuals, and that SA indicators of childhood SES and perceived racial discrimination are important components of adversity that are associated with cognitive performance.

  7. Effect of Contour Shape of Nervous System Electromagnetic Stimulation Coils on the Induced Electrical Field Distribution

    Directory of Open Access Journals (Sweden)

    Daskalov Ivan K

    2002-05-01

    Full Text Available Abstract Background Electromagnetic stimulation of the nervous system has the advantage of reduced discomfort in activating nerves. For brain structures stimulation, it has become a clinically accepted modality. Coil designs usually consider factors such as optimization of induced power, focussing, field shape etc. In this study we are attempting to find the effect of the coil contour shape on the electrical field distribution for magnetic stimulation. Method and results We use the maximum of the induced electric field stimulation in the region of interest as the optimization criterion. This choice required the application of the calculus of variation, with the contour perimeter taken as a pre-set condition. Four types of coils are studied and compared: circular, square, triangular and an 'optimally' shaped contour. The latter yields higher values of the induced electrical field in depths up to about 30 mm, but for depths around 100 mm, the circular shape has a slight advantage. The validity of the model results was checked by experimental measurements in a tank with saline solution, where differences of about 12% were found. In view the accuracy limitations of the computational and measurement methods used, such differences are considered acceptable. Conclusion We applied an optimization approach, using the calculus of variation, which allows to obtain a coil contour shape corresponding to a selected criterion. In this case, the optimal contour showed higher intensities for a longer line along the depth-axis. The method allows modifying the induced field structure and focussing the field to a selected zone or line.

  8. Effect of static shape deformation on aerodynamics and aerothermodynamics of hypersonic inflatable aerodynamic decelerator

    Science.gov (United States)

    Guo, Jinghui; Lin, Guiping; Bu, Xueqin; Fu, Shiming; Chao, Yanmeng

    2017-07-01

    The inflatable aerodynamic decelerator (IAD), which allows heavier and larger payloads and offers flexibility in landing site selection at higher altitudes, possesses potential superiority in next generation space transport system. However, due to the flexibilities of material and structure assembly, IAD inevitably experiences surface deformation during atmospheric entry, which in turn alters the flowfield around the vehicle and leads to the variations of aerodynamics and aerothermodynamics. In the current study, the effect of the static shape deformation on the hypersonic aerodynamics and aerothermodynamics of a stacked tori Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is demonstrated and analyzed in detail by solving compressible Navier-Stokes equations with Menter's shear stress transport (SST) turbulence model. The deformed shape is obtained by structural modeling in the presence of maximum aerodynamic pressure during entry. The numerical results show that the undulating shape deformation makes significant difference to flow structure. In particular, the more curved outboard forebody surface results in local flow separations and reattachments in valleys, which consequently yields remarkable fluctuations of surface conditions with pressure rising in valleys yet dropping on crests while shear stress and heat flux falling in valleys yet rising on crests. Accordingly, compared with the initial (undeformed) shape, the corresponding differences of surface conditions get more striking outboard, with maximum augmentations of 379 pa, 2224 pa, and 19.0 W/cm2, i.e., 9.8%, 305.9%, and 101.6% for the pressure, shear stress and heat flux respectively. Moreover, it is found that, with the increase of angle of attack, the aerodynamic characters and surface heating vary and the aeroheating disparities are evident between the deformed and initial shape. For the deformable HIAD model investigated in this study, the more intense surface conditions and changed flight

  9. Yarkovsky effect and V-shapes: New method to compute family ages

    Science.gov (United States)

    Spoto, F.; Milani, A.; Cellino, A.; Knezevic, Z.; Novakovic, B.; Paolicchi, P.

    2014-07-01

    The computation of family ages is a high-priority goal. As a matter of principle, it can be achieved by using V-shape plots for the families old enough to have the Yarkovsky effect dominating the spread of the proper a and large enough for a statistically significant analysis of the shape. By performing an asteroid family classification with a very enlarged dataset, the results are not just ''more families'', but there are interesting qualitative changes. These are due to the large-number statistics, but also to the larger fraction of smaller objects contained in recently numbered asteroids. We are convinced that our method is effective in adding many smaller asteroids to the core families. As a result, we have a large number of families with very well defined V-shapes, thus with a good possibility of age estimation. We have developed our method to compute ages, which we believe is better than those used previously because it is more objective. Since there are no models for error in absolute magnitude H and for albedo, we have also developed a model of the error in the inverse of the diameter and then we have performed a weighted least-squares fit. We report at least 5/6 examples of dynamical families for which the computation of the V-shape is possible. These examples show the presence of different internal structure of the families, e.g., in the dynamical family of (4) Vesta, we have found two collisional families. The main problem in estimating the ages is the calibration. The difficulty in the Yarkovsky calibration, due to the need to extrapolate from near-Earth asteroids (NEAs) with measured da/dt to main-belt asteroids, is in most cases the main limitation to the accuracy of the age estimation. We obtain an age estimation by scaling the results for the NEA for which there is the best Yarkovsky effect determination, namely (101955) Bennu.

  10. Effects of snow grain shape on climate simulations: sensitivity tests with the Norwegian Earth System Model

    Directory of Open Access Journals (Sweden)

    P. Räisänen

    2017-12-01

    Full Text Available Snow consists of non-spherical grains of various shapes and sizes. Still, in radiative transfer calculations, snow grains are often treated as spherical. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR model and in the Los Alamos sea ice model, version 4 (CICE4, both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM. In this study, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH is compared with another (NONSPH in which the snow shortwave single-scattering properties are based on a combination of three non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (0.77–0.78 in the visible region than in the spherical case ( ≈  0.89. Therefore, for the same effective snow grain size (or equivalently, the same specific projected area, the snow broadband albedo is higher when assuming non-spherical rather than spherical snow grains, typically by 0.02–0.03. Considering the spherical case as the baseline, this results in an instantaneous negative change in net shortwave radiation with a global-mean top-of-the-model value of ca. −0.22 W m−2. Although this global-mean radiative effect is rather modest, the impacts on the climate simulated by NorESM are substantial. The global annual-mean 2 m air temperature in NONSPH is 1.17 K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further demonstrated that the effect of snow grain shape could be largely offset by adjusting the snow grain size. When assuming non-spherical snow grains with the parameterized grain

  11. Effects of snow grain shape on climate simulations: sensitivity tests with the Norwegian Earth System Model

    Science.gov (United States)

    Räisänen, Petri; Makkonen, Risto; Kirkevåg, Alf; Debernard, Jens B.

    2017-12-01

    Snow consists of non-spherical grains of various shapes and sizes. Still, in radiative transfer calculations, snow grains are often treated as spherical. This also applies to the computation of snow albedo in the Snow, Ice, and Aerosol Radiation (SNICAR) model and in the Los Alamos sea ice model, version 4 (CICE4), both of which are employed in the Community Earth System Model and in the Norwegian Earth System Model (NorESM). In this study, we evaluate the effect of snow grain shape on climate simulated by NorESM in a slab ocean configuration of the model. An experiment with spherical snow grains (SPH) is compared with another (NONSPH) in which the snow shortwave single-scattering properties are based on a combination of three non-spherical snow grain shapes optimized using measurements of angular scattering by blowing snow. The key difference between these treatments is that the asymmetry parameter is smaller in the non-spherical case (0.77-0.78 in the visible region) than in the spherical case ( ≈ 0.89). Therefore, for the same effective snow grain size (or equivalently, the same specific projected area), the snow broadband albedo is higher when assuming non-spherical rather than spherical snow grains, typically by 0.02-0.03. Considering the spherical case as the baseline, this results in an instantaneous negative change in net shortwave radiation with a global-mean top-of-the-model value of ca. -0.22 W m-2. Although this global-mean radiative effect is rather modest, the impacts on the climate simulated by NorESM are substantial. The global annual-mean 2 m air temperature in NONSPH is 1.17 K lower than in SPH, with substantially larger differences at high latitudes. The climatic response is amplified by strong snow and sea ice feedbacks. It is further demonstrated that the effect of snow grain shape could be largely offset by adjusting the snow grain size. When assuming non-spherical snow grains with the parameterized grain size increased by ca. 70 %, the

  12. The Effect of pH on Rabbit Septal Cartilage Shape Change: Exploring the Mechanism of Electromechanical Tissue Reshaping

    OpenAIRE

    Tracy, Lauren E.; Wong, Brian J.

    2014-01-01

    Introduction: Electromechanical reshaping (EMR) involves the application of an electrical current to mechanically deformed cartilage to create sustained tissue shape change. Although EMR may evolve to become an inexpensive and reliable way of producing shape change in cartilage during reconstructive surgery, the precise mechanism of EMR is unknown. We aim to examine the isolated effect of protonation (pH) on shape change in cartilage. Methods: Nasal septal cartilages of rabbits were mechanica...

  13. Drug-releasing shape-memory polymers - the role of morphology, processing effects, and matrix degradation.

    Science.gov (United States)

    Wischke, Christian; Behl, Marc; Lendlein, Andreas

    2013-09-01

    Shape-memory polymers (SMPs) have gained interest for temporary drug-release systems that should be anchored in the body by self-sufficient active movements of the polymeric matrix. Based on the so far published scientific literature, this review highlights three aspects that require particular attention when combining SMPs with drug molecules: i) the defined polymer morphology as required for the shape-memory function, ii) the strong effects that processing conditions such as drug-loading methodologies can have on the drug-release pattern from SMPs, and iii) the independent control of drug release and degradation by their timely separation. The combination of SMPs with a drug-release functionality leads to multifunctional carriers that are an interesting technology for pharmaceutical sciences and can be further expanded by new materials such as thermoplastic SMPs or temperature-memory polymers. Experimental studies should include relevant molecules as (model) drugs and provide a thermomechanical characterization also in an aqueous environment, report on the potential effect of drug type and loading levels on the shape-memory functionality, and explore the potential correlation of polymer degradation and drug release.

  14. Calculation of Resonance Interaction Effects Using a Rational Approximation to the Symmetric Resonance Line Shape Function

    International Nuclear Information System (INIS)

    Haeggblom, H.

    1968-08-01

    The method of calculating the resonance interaction effect by series expansions has been studied. Starting from the assumption that the neutron flux in a homogeneous mixture is inversely proportional to the total cross section, the expression for the flux can be simplified by series expansions. Two types of expansions are investigated and it is shown that only one of them is generally applicable. It is also shown that this expansion gives sufficient accuracy if the approximate resonance line shape function is reasonably representative. An investigation is made of the approximation of the resonance shape function with a Gaussian function which in some cases has been used to calculate the interaction effect. It is shown that this approximation is not sufficiently accurate in all cases which can occur in practice. Then, a rational approximation is introduced which in the first order approximation gives the same order of accuracy as a practically exact shape function. The integrations can be made analytically in the complex plane and the method is therefore very fast compared to purely numerical integrations. The method can be applied both to statistically correlated and uncorrelated resonances

  15. 2D net shape weaving for cost effective manufacture of textile reinforced composites

    Science.gov (United States)

    Vo, D. M. P.; Kern, M.; Hoffmann, G.; Cherif, C.

    2017-10-01

    Despite significant weight and performance advantages over metal parts, the today’s demand for fibre-reinforced polymer composites (FRPC) has been limited mainly by their large manufacturing cost. The combination of dry textile preforms and low-cost consolidation processes such as resin transfer molding (RTM) has been appointed as a promising approach to low-cost FRPC manufacture. At the current state of the art, tooling and impregnation technology is well understood whereas preform fabrication technology has not been developed effectively. This paper presents an advanced 2D net shape weaving technology developed with the aim to establish a more cost effective system for the manufacture of dry textile preforms for FRPC. 2D net shape weaving is developed based on open reed weave (ORW) technology and enables the manufacture of 2D contoured woven fabrics with firm edge, so that oversize cutting and hand trimming after molding are no longer required. The introduction of 2D net shape woven fabrics helps to reduce material waste, cycle time and preform manufacturing cost significantly. Furthermore, higher grade of automation in preform fabrication can be achieved.

  16. Calculation of Resonance Interaction Effects Using a Rational Approximation to the Symmetric Resonance Line Shape Function

    Energy Technology Data Exchange (ETDEWEB)

    Haeggblom, H

    1968-08-15

    The method of calculating the resonance interaction effect by series expansions has been studied. Starting from the assumption that the neutron flux in a homogeneous mixture is inversely proportional to the total cross section, the expression for the flux can be simplified by series expansions. Two types of expansions are investigated and it is shown that only one of them is generally applicable. It is also shown that this expansion gives sufficient accuracy if the approximate resonance line shape function is reasonably representative. An investigation is made of the approximation of the resonance shape function with a Gaussian function which in some cases has been used to calculate the interaction effect. It is shown that this approximation is not sufficiently accurate in all cases which can occur in practice. Then, a rational approximation is introduced which in the first order approximation gives the same order of accuracy as a practically exact shape function. The integrations can be made analytically in the complex plane and the method is therefore very fast compared to purely numerical integrations. The method can be applied both to statistically correlated and uncorrelated resonances.

  17. Effect of Local Junction Losses in the Optimization of T-shaped Flow Channels

    Science.gov (United States)

    Kosaraju, Srinivas

    2015-11-01

    T-shaped channels are extensively used in flow distribution applications such as irrigation, chemical dispersion, gas pipelines and space heating and cooling. The geometry of T-shaped channels can be optimized to reduce the overall pressure drop in stem and branch sections. Results of such optimizations are in the form of geometric parameters such as the length and diameter ratios of the stem and branch sections. The traditional approach of this optimization accounts for the pressure drop across the stem and branch sections, however, ignores the pressure drop in the T-junction. In this paper, we conduct geometry optimization while including the effect of local junction losses in laminar flows. From the results, we are able to identify a non-dimensional parameter that can be used to predict the optimal geometric configurations. This parameter can also be used to identify the conditions in which the local junction losses can be ignored during the optimization.

  18. Shape Effect of Crushed Sand Filler on Rheology: A Preliminary Experimental and Numerical Study

    DEFF Research Database (Denmark)

    Spangenberg, Jon; Cepuritis, Rolands; Hovad, Emil

    2016-01-01

    Two types of filler from crushed sand were mixed with cement paste with constant superplasticizer dosage per mass of cement to investigate how their shape affects the rheology. The fillers were mylonitic quartz diorite and limestone produced using Vertical Shaft Impact (VSI) crusher and air...... was quantified with the slump flow test (i.e. mini cone). The shape effect was isolated in the experiments by the use of non overlapping bimodal particle distributions of cement particles with a number average diameter of approximate to 0.01 mm and filler particles with a number average diameter of approximate...... to 0.1 mm. The two filler types were tested with a range of chi-values (volume of cement divided by total volume of solids). The flowability of the matrix increased with decreasing aspect ratios of the filler. However, the chi-value at which the maximum volume fraction threshold was obtained varied...

  19. Effects of laser beam propagation and saturation on the spatial shape of sodium laser guide stars.

    Science.gov (United States)

    Marc, Fabien; Guillet de Chatellus, Hugues; Pique, Jean-Paul

    2009-03-30

    The possibility to produce diffraction-limited images by large telescopes through Adaptive Optics is closely linked to the precision of measurement of the position of the guide star on the wavefront sensor. In the case of laser guide stars, many parameters can lead to a strong distortion on the shape of the LGS spot. Here we study the influence of both the saturation of the sodium layer excited by different types of lasers, the spatial quality of the laser mode at the ground and the influence of the atmospheric turbulence on the upward propagation of the laser beam. Both shape and intensity of the LGS spot are found to depend strongly on these three effects with important consequences on the precision on the wavefront analysis.

  20. Effects of contact cap dimension on dry adhesion of bioinspired mushroom-shaped surfaces

    Science.gov (United States)

    Wang, Yue; Shao, Jinyou; Ding, Yucheng; Li, Xiangming; Tian, Hongmiao; Hu, Hong

    2015-03-01

    Dry adhesion observed in small creatures, such as spiders, insects, and geckos, has many great advantages such as repeatability and strong adhesiveness. In order to mimic these unique performances, fibrillar surface with a mushroom shaped end has drawn lots of attentions because of its advantage in efficiently enhancing adhesion compared with other sphere or simple flat ends. Here, in order to study the effects of contact cap dimension on adhesion strength, patterned surfaces of mushroom-shaped micropillars with differing cap diameters are fabricated based on the conventional photolithography and molding. The normal adhesion strength of these dry adhesives with varying cap diameters is measured with home-built equipment. The strength increases with the rise of cap diameter, and interestingly it becomes strongest when the mushroom caps join together.

  1. Experimental Investigation of the Effect of Particle Shape on Frictional Pressure drop in Particulate Debris Bed

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Kim, Eun Ho; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of)

    2014-10-15

    To ensure the long-term cooling of corium in the reactor cavity, it is important to ensure the coolant ingression into the internally heat generated corium debris bed which is governed by pressure drop in porous media. For this reason, it is necessary to understand pressure drop mechanisms in porous bed to verify the feasibility of water penetration into particulate debris bed. According to the previous investigations on molten fuel-coolant interaction (FCI) experiments, it was found that quenched particulate debris bed was composed of irregular shape particles. Therefore, empirical or semiempirical models based on the Ergun equation (Ergun, 1952) for single-phase flow in porous media composed of single sized spherical particle were developed to consider the effect of particle shape on frictional pressure drop by means of adding a shape factor or modifying the Ergun constants etc. (Leva, 1959, Handley and Heggs, 1968, Macdonald, 1979, Foumeny et al., 1996). An experimental investigate on single-phase frictional pressure drop of water in packed bed was conducted in the transparent cylindrical test section with the inner diameter of 100 mm and the height of 700 mm to study the effect of particle shape on frictional pressure drop in porous media. This paper reports the experimental data for spherical particles with the diameter of 2 mm and 5 mm and cylindrical particles with ED of 2 mm and 5 mm. And also, the experimental data compared with the models to predict frictional pressure drop in particulate bed. The conclusions are summarized as follows. As a result of the experiment to measure frictional pressure drop in particulate bed composed of cylindrical particles the models predict the experimental data well within 22.11 % except the Handley and Heggs model when ED is applied to the models.

  2. Experimental Investigation of the Effect of Particle Shape on Frictional Pressure drop in Particulate Debris Bed

    International Nuclear Information System (INIS)

    Park, Jin Ho; Kim, Eun Ho; Park, Hyun Sun

    2014-01-01

    To ensure the long-term cooling of corium in the reactor cavity, it is important to ensure the coolant ingression into the internally heat generated corium debris bed which is governed by pressure drop in porous media. For this reason, it is necessary to understand pressure drop mechanisms in porous bed to verify the feasibility of water penetration into particulate debris bed. According to the previous investigations on molten fuel-coolant interaction (FCI) experiments, it was found that quenched particulate debris bed was composed of irregular shape particles. Therefore, empirical or semiempirical models based on the Ergun equation (Ergun, 1952) for single-phase flow in porous media composed of single sized spherical particle were developed to consider the effect of particle shape on frictional pressure drop by means of adding a shape factor or modifying the Ergun constants etc. (Leva, 1959, Handley and Heggs, 1968, Macdonald, 1979, Foumeny et al., 1996). An experimental investigate on single-phase frictional pressure drop of water in packed bed was conducted in the transparent cylindrical test section with the inner diameter of 100 mm and the height of 700 mm to study the effect of particle shape on frictional pressure drop in porous media. This paper reports the experimental data for spherical particles with the diameter of 2 mm and 5 mm and cylindrical particles with ED of 2 mm and 5 mm. And also, the experimental data compared with the models to predict frictional pressure drop in particulate bed. The conclusions are summarized as follows. As a result of the experiment to measure frictional pressure drop in particulate bed composed of cylindrical particles the models predict the experimental data well within 22.11 % except the Handley and Heggs model when ED is applied to the models

  3. Color appearance of familiar objects: effects of object shape, texture, and illumination changes.

    Science.gov (United States)

    Olkkonen, Maria; Hansen, Thorsten; Gegenfurtner, Karl R

    2008-05-26

    People perceive roughly constant surface colors despite large changes in illumination. The familiarity of colors of some natural objects might help achieve this feat through direct modulation of the objects' color appearance. Research on memory colors and color appearance has yielded controversial results and due to the employed methods has often confounded perceptual with semantic effects. We studied the effect of memory colors on color appearance by presenting photographs of fruit on a monitor under various simulated illuminations and by asking observers to make either achromatic or typical color settings without placing demands on short-term memory or semantic processing. In a control condition, we presented photographs of 3D fruit shapes without texture and 2D outline shapes. We found that (1) achromatic settings for fruit were systematically biased away from the gray point toward the opposite direction of a fruit's memory color; (2) the strength of the effect depended on the degree of naturalness of the stimuli; and (3) the effect was evident under all tested illuminations, being strongest for illuminations whose chromaticity was closest to the stimulus chromaticity. We conclude that the visual identity of an object has a measurable effect on color perception, and that this effect is robust under illuminant changes, indicating its potential significance as an additional mechanism for color constancy.

  4. Density effect on the mixing efficiency and flow modes in T-shaped micromixers

    Directory of Open Access Journals (Sweden)

    Lobasov Alexander

    2017-01-01

    Full Text Available Flow patterns and mixing of liquids with different densities in T-shaped micromixers are numerically investigated at Reynolds number range from 1 to 250. The density ratio of the mixing media varies from 1 to 2; its effect on the flow structure and the mixing is studied. The dependences of the mixing efficiency and the pressure difference in this mixer on the density ratio and the Reynolds number are obtained. It is shown that the density ratio has a considerable effect on the flow structure, especially before the transition from the symmetric to the asymmetric flow pattern.

  5. SQUEEZING EFFECT OF RAIL LOADED BY SEMI-SLEEPERS HAVING L-SHAPED CROSS-SECTION

    Directory of Open Access Journals (Sweden)

    V. N. Sukhodoev

    2015-01-01

    Full Text Available The paper considers a problem on introduction of a conception and regularities of “squeezing effect of a rail loaded non centrally by semi-sleepers having L-shaped cross-section” exemplified by belt-type tramway. Its advantages are ensured by doubled non centrally loaded foundations these are semi-sleepers. Semi-sleeper of L-shape cross-section is a lever of L-shape form, transforming a vertical load into horizontal ones and foundation squeezing. Properties of two semi-sleepers being doubled, orientated to each other and non centrally loaded have been used in order to create a positive effect. A horizontal force creates squeezing and it is revealed as a component of a vertical load during displacements which functionally depend on foundation squeezing. These dependences demonstrate that strength and deformation properties of earth foundation of vertical direction are used for creation of horizontal properties of sleeper vertical shoulder.The paper studies mechanics pertaining to a squeezing effect of a rail loaded by semi-sleepers having L-shaped cross-section. It has been established that the rail squeezing effect results from squeezing process executed in two mutually perpendicular directions (reduction of cross-sectional area by load of a rail wheel with spacers if they are set inside of a sleeper-mechanism on an elastic foundation.Methodology for calculation of parameters on the rail reduction effect is considered as a tool for handling of applied problems on belt-type tramways. Results of the proposed rail reduction effect in problem statement for elastic conditions, with unchanged cross-sectional dimension of a rail line and introduction of correction ratio coefficients due to new initial load data have recommended for practical application as reliable values.The paper has revealed a proportional dependence of the rail reduction effect according to strength on the resultant value of reaction pressure, eccentricity difference of the

  6. Fano effect and Andreev bound states in T-shape double quantum dots

    International Nuclear Information System (INIS)

    Calle, A.M.; Pacheco, M.; Orellana, P.A.

    2013-01-01

    In this Letter, we investigate the transport through a T-shaped double quantum dot coupled to two normal metal leads left and right and a superconducting lead. Analytical expressions of Andreev transmission and local density of states of the system at zero temperature have been obtained. We study the role of the superconducting lead in the quantum interferometric features of the double quantum dot. We report for first time the Fano effect produced by Andreev bound states in a side quantum dot. Our results show that as a consequence of quantum interference and proximity effect, the transmission from normal to normal lead exhibits Fano resonances due to Andreev bound states. We find that this interference effect allows us to study the Andreev bound states in the changes in the conductance between two normal leads. - Highlights: • Transport properties of a double quantum dot coupled in T-shape configuration to conducting and superconducting leads are studied. • We report Fano antiresonances in the normal transmission due to the Andreev reflections in the superconducting lead. • We report for first time the Fano effect produced by Andreev bound states in a side quantum dot. • Fano effect allows us to study the Andreev bound states in the changes in the conductance between two normal leads. • Andreev bound states survives even for strong dot-superconductor coupling

  7. Investigating the Effects of I-Shaped Cores in an Outer-Rotor Transverse Flux Permanent Magnet Generator

    DEFF Research Database (Denmark)

    Hosseini, Seyedmohsen; Moghani, Javad Shokrollahi; Jensen, Bogi Bech

    2011-01-01

    This paper deals with the effects of I-shaped cores in an outer-rotor transverse flux permanent magnet generator. Performance characteristics of a typical outer-rotor transverse flux permanent magnet generator are obtained in two cases; with and without I-shaped cores. The results show that altho...... the advantages and disadvantage of using I-shaped cores and emphasizes the necessity of performing a tradeoff study between using and not using I-shaped cores in practical transverse flux permanent magnet generators....

  8. Combined Pyroelectric, Piezoelectric and Shape Memory Effects for Thermal Energy Harvesting

    International Nuclear Information System (INIS)

    Zakharov, D; Gusarov, B; Cugat, O; Delamare, J; Gimeno, L; Gusarova, E; Viala, B

    2013-01-01

    This work proposes an enhanced method for thermal energy harvesting exploiting combined pyroelectric, piezoelectric and shape memory (SME) effects, and presents its experimental validation. A material which is pyroelectric is also piezoelectric. If it is combined with a material with SME, which generates large strain and stress in a rather narrow temperature range, the resulting composite material would generate voltage from temperature variations using two different energy conversion principles at once: (1) pyroelectric effect, (2) piezoelectric effect driven by SME. A Macro Fiber Composite piezoelectric was shown here to exhibit significant pyroelectric effect (∼4 V/°C). When combining it with a SME Ti-Ni-Cu alloy into a laminated structure, this effect increased by 50%. This increase may be an order of magnitude higher for an optimized system. Such composites open an opportunity to harvest thermal energy from natural sources, since this method can increase the rather low efficiency of current pyroelectric materials especially for small temperature variations

  9. Effect of surface roughness variation on the transmission characteristics of D-shaped fibers with ambient index change

    International Nuclear Information System (INIS)

    Kim, Hyun-Joo; Kwon, Oh-Jang; Han, Young-Geun

    2010-01-01

    The influence of surface roughness on the sensitivity of D-shaped fibers to changes in the ambient index was investigated. In order to obtain D-shaped fibers with different surface roughness, we polished one side of the fibers by using different abrasive grits. The topographies of the surfaces of the polished D-shaped fibers were then observed by using atomic force microscopy (AFM). The light scattered from the rough surfaces of the D-shaped fibers was measured by using optical microscopy. The effect of an ambient index change on the transmission characteristics of D-shaped fibers was measured for various values of the surface roughness. The experimental results indicate that variations in the surface roughness have a considerable influence on the sensitivity of the transmission characteristics of D-shaped fibers to changes in the ambient index.

  10. Formation of two-way shape memory effect in rapid-quenched TiNiCu alloys

    International Nuclear Information System (INIS)

    Shelyakov, A.V.; Bykovsky, Yu.A.; Matveeva, N.M.; Kovneristy, Yu.K.

    1995-01-01

    Recently we have developed a number of devices for an optical radiation control based on the shape memory effect. A blind of rapid-quenched TiNiCu alloy having a two-way shape memory in bending was used as a basic element. So far as the rapid quenched alloy used is amorphous in initial state, it needs thermal annealing to form shape memory. This paper describes procedure of thermo-mechanical treatment, that allows to form desired two-way shape memory immediately during thermal annealing of amorphous alloy without training. It was shown that degree of two-way shape recovery depends critically on initial strain, temperature and duration of the annealing. It was experimentally determined optimum parameters of thermo-mechanical treatment to achieve maximum two-way shape memory. (orig.)

  11. Factorization and shape-function effects in inclusive B-meson decays

    International Nuclear Information System (INIS)

    Bosch, S.W.; Lange, B.O.; Neubert, M.; Paz, G.

    2004-01-01

    Using methods of effective field theory, factorized expressions for arbitrary B-bar ->Xul-ν-bar decay distributions in the shape-function region of large hadronic energy and moderate hadronic invariant mass are derived. Large logarithms are resummed at next-to-leading order in renormalization-group improved perturbation theory. The operator product expansion is employed to relate moments of the renormalized shape function with HQET parameters such as mb, Λ-bar and λ1 defined in a new physical subtraction scheme. An analytic expression for the asymptotic behavior of the shape function is obtained, which reveals that it is not positive definite. Explicit expressions are presented for the charged-lepton energy spectrum, the hadronic invariant mass distribution, and the spectrum in the hadronic light-cone momentum P+=EH-|P->H|. A new method for a precision measurement of |Vub| is proposed, which combines good theoretical control with high efficiency and a powerful discrimination against charm background

  12. EFFECT OF BODY SHAPE ON THE AERODYNAMICS OF PROJECTILES AT SUPERSONIC SPEEDS

    Directory of Open Access Journals (Sweden)

    ABDULKAREEM SH. MAHDI

    2008-12-01

    Full Text Available An investigation has been made to predict the effects of forebody and afterbody shapes on the aerodynamic characteristics of several projectile bodies at supersonic speeds using analytical methods combined with semi-empirical design curves. The considered projectile bodies had a length-to-diameter ratio of 6.67 and included three variations of forebody shape and three variations of afterbody shape. The results, which are verified by comparison with available experimental data, indicated that the lowest drag was achieved with a cone-cylinder at the considered Mach number range. It is also shown that the drag can be reduced by boattailing the afterbody. The centre-of-pressure assumed a slightly rearward location for the ogive-cylinder configuration when compared to the configuration with boattailed afterbody where it was the most forward. With the exception of the boattailed afterbody, all the bodies indicated inherent static stability above Mach number 2 for a centre-of-gravity location at about 40% from the body nose.

  13. Investigation of the effects on Charpy impact characteristics by shape of pendulum striking edge

    International Nuclear Information System (INIS)

    Kawai, Toshihiko; Etoh, Mikio; Hanawa, Namio; Shibaike, Masayuki; Inoue, Kazuo.

    1983-01-01

    Charpy impact test is used versatilely and practically as the method of evaluating the toughness of metals. In Japan, usually the JIS type testing machines are used, but recently, the test with ASTM type testing machines has been often demanded for steel materials for export or for nuclear use. Accordingly, the testing machines of both types must be installed, the testing works become troublesome, and the costs of initial investment, maintenance, management and so on increase. When the standards in various countries were investigated, the stipulation on the various particulars of the testing machines was almost similar except the shape of striking edges, which are 8mm radius in ASTM and 2mm radius in other standards. Recently it was clarified that there was some difference between the impact values of high toughness steel using JIS and ASTM machines. In order to clarify the cause of this difference and to unify the shape of edges, the investigation was carried out by the working group. The investigation of the effect of the difference of edge shapes on impact values, the analysis of fracture phenomena in impact test and the consideration on the results are reported. ASTM type testing machines should not be used for mild steel when absorbed energy exceeds 10kgf-m. (Kako, I.)

  14. Effects of pellet shape on the fuel failure behavior under a RIA condition

    International Nuclear Information System (INIS)

    Hosokawa, Takanori; Hoshi, Tsutao; Yanagihara, Satoshi; Iwamura, Takamichi; Orita, Yoshihiko.

    1980-10-01

    The two types of fuel rods with different pellet shaped, i.e. flat pellets and dished pellets, were tested in the NSRR to investigate the effects of pellet shapes on the fuel failure behavior under an RIA condition and the results were compared with those of the chamfered pellet fuel rods which are used as the reference rod in the NSRR experiments. In addition, the deformation of pellets due to thermal expansion is calculated by using an FEM computer code. Through the above results, following conclusions are obtained. (1) In the experiments, insignificant differences on the cladding surface temperature responses and the appearance of post-irradiated rods are observed in each type of rods. (2) Evident differences on the deformation of fuel pellets have not appeared in the calculation. (3) In the RIA conditions, it is concluded that the fuel failure behavior and threshold energy might not be affected by pellet shape of which size is in the range of the current LWR's fuel rods. (author)

  15. Effects of shape differences in the level densities of three formalisms on calculated cross-sections

    International Nuclear Information System (INIS)

    Fu, C.Y.; Larson, D.C.

    1998-01-01

    Effects of shape differences in the level densities of three formalisms on calculated cross-sections and particle emission spectra are described. Reactions for incident neutrons up to 20 MeV on 58 Ni are chosen for illustrations. Level density parameters for one of the formalisms are determined from the available neutron resonance data for one residual nuclide in the binary channels and from fitting the measured (n,n'), (n,p) and (n,α) cross-sections for the other two residual nuclides. Level density parameters for the other two formalisms are determined such that they yield the same values as the above one at two selected energies. This procedure forces the level densities from the three formalisms used for the binary pat of the calculation to be as close as possible. The remaining differences are in their energy dependences (shapes). It is shown that these shape differences alone are enough to cause the calculated cross-sections and particle emission spectra to be different by up to 60%. (author)

  16. Effects of carrying a backpack in a symmetrical manner on the shape of the feet.

    Science.gov (United States)

    Drzał-Grabiec, Justyna; Snela, Sławomir; Rachwał, Maciej; Rykała, Justyna; Podgórska, Justyna

    2013-01-01

    The aim of this study was to assess changes in the shape of the feet while carrying a backpack constituting 10% of a child's weight. It was an observational, cross-sectional study involving 118 primary school children aged 11-13 years. Selected parameters of foot shape were assessed in both a normal position and with a backpack using podoscopy and a CQ-ST examination device. The study revealed significant differences in the length and width of the right and left feet between assessments. Moreover, the longitudinal arch of the foot was significantly lowered and deformity of the great toe was reported. Carrying a backpack constituting 10% of a child's weight results in lowering of the longitudinal and traverse arches of the feet and advanced toe deformities. We performed an observational, cross-sectional study examining the effect of carrying a backpack constituting 10% of a child's weight on parameters of foot shape and observed significant lowering of the longitudinal and traverse arches of the feet and advanced toe deformities.

  17. The Effect of Sterilization on Size and Shape of Fat Globules in Model Processed Cheese Samples

    Directory of Open Access Journals (Sweden)

    B. Tremlová

    2006-01-01

    Full Text Available Model cheese samples from 4 independent productions were heat sterilized (117 °C, 20 minutes after the melting process and packing with an aim to prolong their durability. The objective of the study was to assess changes in the size and shape of fat globules due to heat sterilization by using image analysis methods. The study included a selection of suitable methods of preparation mounts, taking microphotographs and making overlays for automatic processing of photographs by image analyser, ascertaining parameters to determine the size and shape of fat globules and statistical analysis of results obtained. The results of the experiment suggest that changes in shape of fat globules due to heat sterilization are not unequivocal. We found that the size of fat globules was significantly increased (p < 0.01 due to heat sterilization (117 °C, 20 min, and the shares of small fat globules (up to 500 μm2, or 100 μm2 in the samples of heat sterilized processed cheese were decreased. The results imply that the image analysis method is very useful when assessing the effect of technological process on the quality of processed cheese quality.

  18. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Chan, V.S.; Chen, L.

    1998-12-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n ∼ 2--9 and a fast growth time γ -1 = 20--150 micros are often observed prior to the first giant type 1 ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n > 1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region

  19. Effect of Particle Shape on Mechanical Behaviors of Rocks: A Numerical Study Using Clumped Particle Model

    Science.gov (United States)

    Rong, Guan; Liu, Guang; Zhou, Chuang-bing

    2013-01-01

    Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied. PMID:23997677

  20. Effect of particle shape on mechanical behaviors of rocks: a numerical study using clumped particle model.

    Science.gov (United States)

    Rong, Guan; Liu, Guang; Hou, Di; Zhou, Chuang-Bing

    2013-01-01

    Since rocks are aggregates of mineral particles, the effect of mineral microstructure on macroscopic mechanical behaviors of rocks is inneglectable. Rock samples of four different particle shapes are established in this study based on clumped particle model, and a sphericity index is used to quantify particle shape. Model parameters for simulation in PFC are obtained by triaxial compression test of quartz sandstone, and simulation of triaxial compression test is then conducted on four rock samples with different particle shapes. It is seen from the results that stress thresholds of rock samples such as crack initiation stress, crack damage stress, and peak stress decrease with the increasing of the sphericity index. The increase of sphericity leads to a drop of elastic modulus and a rise in Poisson ratio, while the decreasing sphericity usually results in the increase of cohesion and internal friction angle. Based on volume change of rock samples during simulation of triaxial compression test, variation of dilation angle with plastic strain is also studied.

  1. Effects of plasma shape and profiles on edge stability in DIII-D

    International Nuclear Information System (INIS)

    Lao, L.L.; Ferron, J.R.; Miller, R.L.

    2001-01-01

    The results of recent experimental and theoretical studies concerning the effects of plasma shape and current and pressure profiles on edge instabilities in DIII-D are presented. Magnetic oscillations with toroidal mode number n∼2-9 and a fast growth time γ -1 =20-150μs are often observed prior to the first giant type I ELM in discharges with moderate squareness. High n ideal ballooning second stability access encourages edge instabilities by facilitating the buildup of the edge pressure gradient and bootstrap current density which destabilize the intermediate to low n modes. Analysis suggests that discharges with large edge pressure gradient and bootstrap current density are more unstable to n>1 modes. Calculations and experimental results show that ELM amplitude and frequency can be varied by controlling access to the second ballooning stability regime at the edge through variation of the squareness of the discharge shape. A new method is proposed to control edge instabilities by reducing access to the second ballooning stability regime at the edge using high order local perturbation of the plasma shape in the outboard bad curvature region. (author)

  2. Principal shapes and squeezed limits in the effective field theory of large scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Bertolini, Daniele; Solon, Mikhail P., E-mail: dbertolini@lbl.gov, E-mail: mpsolon@lbl.gov [Berkeley Center for Theoretical Physics, University of California, South Hall Road, Berkeley, CA, 94720 (United States)

    2016-11-01

    We apply an orthogonalization procedure on the effective field theory of large scale structure (EFT of LSS) shapes, relevant for the angle-averaged bispectrum and non-Gaussian covariance of the matter power spectrum at one loop. Assuming natural-sized EFT parameters, this identifies a linear combination of EFT shapes—referred to as the principal shape—that gives the dominant contribution for the whole kinematic plane, with subdominant combinations suppressed by a few orders of magnitude. For the covariance, our orthogonal transformation is in excellent agreement with a principal component analysis applied to available data. Additionally we find that, for both observables, the coefficients of the principal shapes are well approximated by the EFT coefficients appearing in the squeezed limit, and are thus measurable from power spectrum response functions. Employing data from N-body simulations for the growth-only response, we measure the single EFT coefficient describing the angle-averaged bispectrum with Ο (10%) precision. These methods of shape orthogonalization and measurement of coefficients from response functions are valuable tools for developing the EFT of LSS framework, and can be applied to more general observables.

  3. Effects of radiator shapes on the bubble diving and dispersion of ultrasonic argon process.

    Science.gov (United States)

    Liu, Xuan; Xue, Jilai; Zhao, Qiang; Le, Qichi; Zhang, Zhiqiang

    2018-03-01

    In this work, three ultrasonic radiators in different shapes have been designed in order to investigate the effects of radiator shapes on the argon bubble dispersion and diving as well as the degassing efficiency on magnesium melt. The radiator shape has a strong influence on the bubble diving and dispersion by ultrasound. A massive argon bubble slowly flows out from the radiator with the hemispherical cap, due to the covering hemispherical cap. Using a concave radiator can intensively crush the argon bubbles and drive them much deep into the water/melt, depending on the competition between the argon flow and opposite joint shear force from the concave surface. The evolution of wall bubbles involves the ultrasonic cavities carrying dissolved gas, migrating to the vessel wall, and escaping from the liquid. Hydrogen removal can be efficiently achieved using a concave radiator. The hydrogen content can be reduced from 22.3 μg/g down to 8.7 μg/g. Mechanical properties are significantly promoted, due to the structure refinement and efficient hydrogen removal. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Effect of radial head implant shape on joint contact area and location during static loading.

    Science.gov (United States)

    Shannon, Hannah L; Deluce, Simon R; Lalone, Emily A; Willing, Ryan; King, Graham J W; Johnson, James A

    2015-04-01

    To examine the effect of implant shape on radiocapitellar joint contact area and location in vitro. We used 8 fresh-frozen cadaveric upper extremities. An elbow loading simulator examined joint contact in pronation, neutral rotation, and supination with the elbow at 90° flexion. Muscle tendons were attached to pneumatic actuators to allow for computer-controlled loading to achieve the desired forearm rotation. We performed testing with the native radial head, an axisymmetric implant, a reverse-engineered patient-specific implant, and a population-based quasi-anatomic implant. Implants were inserted using computer navigation. Contact area and location were quantified using a casting technique. We found no significant difference between contact locations for the native radial head and the 3 implants. All of the implants had a contact area lower than the native radial head; however, only the axisymmetric implant was significantly different. There was no significant difference in contact area between implant shapes. The similar contact areas and locations of the 3 implant designs suggest that the shape of the implant may not be important with respect to radiocapitellar joint contact mechanics when placed optimally using computer navigation. Further work is needed to explore the sensitivity of radial head implant malpositioning on articular contact. The lower contact area of the radial head implants relative to the native radial head is similar to previous benchtop studies and is likely the result of the greater stiffness of the implant. Radial head implant shape does not appear to have a pronounced influence on articular contact, and both axisymmetric and anatomic metal designs result in elevated cartilage stress relative to the intact state. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  5. Effects of shape, size, and pyrene doping on electronic properties of graphene nanoflakes.

    Science.gov (United States)

    Kuamit, Thanawit; Ratanasak, Manussada; Rungnim, Chompoonut; Parasuk, Vudhichai

    2017-11-25

    Effects of size, shape, and pyrene doping on electronic properties of graphene nanoflakes (GNFs) were theoretically investigated using density functional theory method with PBE, B3PW91, and M06-2X functionals and cc-pVDZ basis set. Two shapes of zigzag GNFs, hexagonal (HGN) and rhomboidal (RGN), were considered. The energy band gap of GNF depends on shape and decreases with size. The HGN has larger band gap energy (1.23-3.96 eV) than the RGN (0.13-2.12 eV). The doping of pyrene and pyrene derivatives on both HGN and RGN was also studied. The adsorption energy of pyrene and pyrene derivatives on GNF does not depend on the shape of GNFs with energies between 21 and 27 kcal mol -1 . The substituent on pyrene enhances the binding to GNF but the strength does not depend on electron withdrawing or donating capability. The doping by pyrene and pyrene derivatives also shifts the HOMO and LUMO energies of GNFs. Both positive (destabilizing) and negative (stabilizing) shifts on HOMO and LUMO of GNFs were seen. The direction and magnitude of the shift do not follow the electron withdrawing and donating capability of pyrene substituents. However, only a slight shift was observed for doped RGN. A shift of 0.19 eV was noticed for HOMO of HGN doped with 1-aminopyrene (pyNH 2 ) and of 0.04 eV for LUMO of HGN doped with 1-pyrenecarboxylic acid (pyCOOH). Graphical Abstract HOMO and LUMO Energies of pyrene/pyrene derivatives doped Graphene Nanoflakes.

  6. Effects of shape and stroke parameters on the propulsion performance of an axisymmetric swimmer.

    Science.gov (United States)

    Peng, Jifeng; Alben, Silas

    2012-03-01

    In nature, there exists a special group of aquatic animals which have an axisymmetric body and whose primary swimming mechanism is to use periodic body contractions to generate vortex rings in the surrounding fluid. Using jellyfish medusae as an example, this study develops a mathematical model of body kinematics of an axisymmetric swimmer and uses a computational approach to investigate the induced vortex wakes. Wake characteristics are identified for swimmers using jet propulsion and rowing, two mechanisms identified in previous studies of medusan propulsion. The parameter space of body kinematics is explored through four quantities: a measure of body shape, stroke amplitude, the ratio between body contraction duration and extension duration, and the pulsing frequency. The effects of these parameters on thrust, input power requirement and circulation production are quantified. Two metrics, cruising speed and energy cost of locomotion, are used to evaluate the propulsion performance. The study finds that a more prolate-shaped swimmer with larger stroke amplitudes is able to swim faster, but its cost of locomotion is also higher. In contrast, a more oblate-shaped swimmer with smaller stroke amplitudes uses less energy for its locomotion, but swims more slowly. Compared with symmetric strokes with equal durations of contraction and extension, faster bell contractions increase the swimming speed whereas faster bell extensions decrease it, but both require a larger energy input. This study shows that besides the well-studied correlations between medusan body shape and locomotion, stroke variables also affect the propulsion performance. It provides a framework for comparing the propulsion performance of axisymmetric swimmers based on their body kinematics when it is difficult to measure and analyze their wakes empirically. The knowledge from this study is also useful for the design of robotic swimmers that use axisymmetric body contractions for propulsion.

  7. Effects of shape and stroke parameters on the propulsion performance of an axisymmetric swimmer

    International Nuclear Information System (INIS)

    Peng Jifeng; Alben, Silas

    2012-01-01

    In nature, there exists a special group of aquatic animals which have an axisymmetric body and whose primary swimming mechanism is to use periodic body contractions to generate vortex rings in the surrounding fluid. Using jellyfish medusae as an example, this study develops a mathematical model of body kinematics of an axisymmetric swimmer and uses a computational approach to investigate the induced vortex wakes. Wake characteristics are identified for swimmers using jet propulsion and rowing, two mechanisms identified in previous studies of medusan propulsion. The parameter space of body kinematics is explored through four quantities: a measure of body shape, stroke amplitude, the ratio between body contraction duration and extension duration, and the pulsing frequency. The effects of these parameters on thrust, input power requirement and circulation production are quantified. Two metrics, cruising speed and energy cost of locomotion, are used to evaluate the propulsion performance. The study finds that a more prolate-shaped swimmer with larger stroke amplitudes is able to swim faster, but its cost of locomotion is also higher. In contrast, a more oblate-shaped swimmer with smaller stroke amplitudes uses less energy for its locomotion, but swims more slowly. Compared with symmetric strokes with equal durations of contraction and extension, faster bell contractions increase the swimming speed whereas faster bell extensions decrease it, but both require a larger energy input. This study shows that besides the well-studied correlations between medusan body shape and locomotion, stroke variables also affect the propulsion performance. It provides a framework for comparing the propulsion performance of axisymmetric swimmers based on their body kinematics when it is difficult to measure and analyze their wakes empirically. The knowledge from this study is also useful for the design of robotic swimmers that use axisymmetric body contractions for propulsion. (paper)

  8. Effects of Particle Size and Shape on U-Mo/Al Thermal Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Tae-Won; Sohn, Dong-Seong [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2014-10-15

    The thermal conductivity of atomized U-Mo/Al dispersion fuels was measured only by Lee et al. by laser-flash and differential scanning calorimetry (DSC) methods. For the U-Mo particles, they are deformed during manufacturing process such as hot rolling and during irradiation by the creep deformation. Fricke developed a model for the effective thermal conductivity of a dilute suspension of randomly oriented spheroidal particles. In general, the thermal conductivity of composite increase when the particle shape is not sphere. This model is also based on continuum theory which assumes both temperature and heat flux are continuous across the interface. Kapitza, however, showed that there is a discontinuity in temperature across the interface at metal/liquid helium interface. In general, the discontinuity is from the thermal resistance at the interface. If the thermal resistance has a significant impact on the thermal conductivity, particle size is one of the essential parameter for determining the effective thermal conductivity of composite materials. Every, et al modified Bruggeman model to consider the interfacial thermal resistance. The U-Mo/Al dispersion fuel thermal conductivity calculation can be improved by considering the anisotropic effects and interface thermal resistances. There have been various works to analyze the thermal conductivity through Finite Element Method (FEM). Coulson developed a realistic FEM model to calculate the effective thermal conductivity of the fuel meat. This FEM model does not consider the anisotropic effects and interface thermal resistances. Therefore, these effects can be evaluated by comparing the FEM calculated effective thermal conductivity with measured data. In this work, the FEM analysis was done and the anisotropic effects and interface thermal resistances was estimated. From this results, the particle shape and size effects will be discussed. Many thermal conductivity models for the particle dispersed composites have been

  9. Effects of Particle Size and Shape on U-Mo/Al Thermal Conductivity

    International Nuclear Information System (INIS)

    Cho, Tae-Won; Sohn, Dong-Seong

    2014-01-01

    The thermal conductivity of atomized U-Mo/Al dispersion fuels was measured only by Lee et al. by laser-flash and differential scanning calorimetry (DSC) methods. For the U-Mo particles, they are deformed during manufacturing process such as hot rolling and during irradiation by the creep deformation. Fricke developed a model for the effective thermal conductivity of a dilute suspension of randomly oriented spheroidal particles. In general, the thermal conductivity of composite increase when the particle shape is not sphere. This model is also based on continuum theory which assumes both temperature and heat flux are continuous across the interface. Kapitza, however, showed that there is a discontinuity in temperature across the interface at metal/liquid helium interface. In general, the discontinuity is from the thermal resistance at the interface. If the thermal resistance has a significant impact on the thermal conductivity, particle size is one of the essential parameter for determining the effective thermal conductivity of composite materials. Every, et al modified Bruggeman model to consider the interfacial thermal resistance. The U-Mo/Al dispersion fuel thermal conductivity calculation can be improved by considering the anisotropic effects and interface thermal resistances. There have been various works to analyze the thermal conductivity through Finite Element Method (FEM). Coulson developed a realistic FEM model to calculate the effective thermal conductivity of the fuel meat. This FEM model does not consider the anisotropic effects and interface thermal resistances. Therefore, these effects can be evaluated by comparing the FEM calculated effective thermal conductivity with measured data. In this work, the FEM analysis was done and the anisotropic effects and interface thermal resistances was estimated. From this results, the particle shape and size effects will be discussed. Many thermal conductivity models for the particle dispersed composites have been

  10. Mitigation of Adverse Effects Caused by Shock Wave Boundary Layer Interactions Through Optimal Wall Shaping

    Science.gov (United States)

    Liou, May-Fun; Lee, Byung Joon

    2013-01-01

    It is known that the adverse effects of shock wave boundary layer interactions in high speed inlets include reduced total pressure recovery and highly distorted flow at the aerodynamic interface plane (AIP). This paper presents a design method for flow control which creates perturbations in geometry. These perturbations are tailored to change the flow structures in order to minimize shock wave boundary layer interactions (SWBLI) inside supersonic inlets. Optimizing the shape of two dimensional micro-size bumps is shown to be a very effective flow control method for two-dimensional SWBLI. In investigating the three dimensional SWBLI, a square duct is employed as a baseline. To investigate the mechanism whereby the geometric elements of the baseline, i.e. the bottom wall, the sidewall and the corner, exert influence on the flow's aerodynamic characteristics, each element is studied and optimized separately. It is found that arrays of micro-size bumps on the bottom wall of the duct have little effect in improving total pressure recovery though they are useful in suppressing the incipient separation in three-dimensional problems. Shaping sidewall geometry is effective in re-distributing flow on the side wall and results in a less distorted flow at the exit. Subsequently, a near 50% reduction in distortion is achieved. A simple change in corner geometry resulted in a 2.4% improvement in total pressure recovery.

  11. Effect of resonance line shape on precision measurements of nuclear magnetic resonance shifts

    International Nuclear Information System (INIS)

    Kachurin, A.M.; Smelyanskij, A.Ya.

    1986-01-01

    Effect of resonance line shape on the systematic error of precision measurements of nuclear magnetic resonance (NMR) shifts of high resolution (on the center of NMR dispersion line) is analysed. Effect of the device resonance line form-function asymmetry is evaluated; the form-function is determined by configuration of the spectrometer magnetic field and enters the convolution, which describes the resonance line form. It is shown that with the increase of the relaxation line width the form-function effect on the measurement error yields to zero. The form-function effect on measurements and correction of a phase angle of NMR detection is evaluated. The method of semiquantitative evaluation of resonance line and NMR spectrometer parameters, guaranteeing the systematic error of the given infinitesimal, is presented

  12. Sexual Dimorphism and Allometric Effects Associated With the Wing Shape of Seven Moth Species of Sphingidae (Lepidoptera: Bombycoidea).

    Science.gov (United States)

    de Camargo, Willian Rogers Ferreira; de Camargo, Nícholas Ferreira; Corrêa, Danilo do Carmo Vieira; de Camargo, Amabílio J Aires; Diniz, Ivone Rezende

    2015-01-01

    Sexual dimorphism is a pronounced pattern of intraspecific variation in Lepidoptera. However, moths of the family Sphingidae (Lepidoptera: Bombycoidea) are considered exceptions to this rule. We used geometric morphometric techniques to detect shape and size sexual dimorphism in the fore and hindwings of seven hawkmoth species. The shape variables produced were then subjected to a discriminant analysis. The allometric effects were measured with a simple regression between the canonical variables and the centroid size. We also used the normalized residuals to assess the nonallometric component of shape variation with a t-test. The deformations in wing shape between sexes per species were assessed with a regression between the nonreduced shape variables and the residuals. We found sexual dimorphism in both wings in all analyzed species, and that the allometric effects were responsible for much of the wing shape variation between the sexes. However, when we removed the size effects, we observed shape sexual dimorphism. It is very common for females to be larger than males in Lepidoptera, so it is expected that the shape of structures such as wings suffers deformations in order to preserve their function. However, sources of variation other than allometry could be a reflection of different reproductive flight behavior (long flights in search for sexual mates in males, and flight in search for host plants in females). © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

  13. The effect of magnetic field on the shape of etch pits of paracetamol crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ivashchenko, V.E. [Kemerovo State University, Novosibirsk (Russian Federation); Research and Educational Center, Novosibirsk State University (Russian Federation); Boldyrev, V.V.; Shakhtshneider, T.P. [Institute of Solid State Chemistry and Mechanochemistry, RAS, Novosibirsk (Russian Federation); Zakharov, Yu.A.; Krasheninin, V.I. [Kemerovo State University, Novosibirsk (Russian Federation); Ermakov, A.E. [Institute of Physics of Metals, Ural Branch of RAS, Ekaterinburg (Russian Federation)

    2002-04-01

    In the present study we investigate the effect of magnetic field on the shape of etch pits of the crystals of p-hydroxyacetanilide (paracetamol), which is widely used in pharmacy as antipyretic, antiphlogistic medicine. It was discovered that the magnetic field (H=0.5 T, {tau}=15 min) changes the morphology of etch pits and shifts dislocations in paracetamol crystal. Activation energy of the changes induced by the action of the magnetic field was determined to be 63 kJ/mol, which is comparable with the energy of hydrogen bonds in crystal lattice. (orig.)

  14. Shaping the composition profiles in heteroepitaxial quantum dots: Interplay of thermodynamic and kinetic effects

    Directory of Open Access Journals (Sweden)

    C. Georgiou

    2014-07-01

    Full Text Available Atomistic Monte Carlo simulations, coupling thermodynamic and kinetic effects, resolve a longstanding controversy regarding the origin of composition profiles in heteroepitaxial SiGe quantum dots. It is shown that profiles with cores rich in the unstrained (Si component derive from near-equilibrium processes and intraisland diffusion. Profiles with cores rich in the strained (Ge component are of nonequilibrium nature, i.e., they are strain driven but kinetically limited. They are shaped by the distribution of kinetic barriers of atomic diffusion in the islands. The diffusion pathways are clearly revealed for the first time. Geometrical kinetics play a minor role.

  15. Effect of initial void shape on ductile failure in a shear field

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2015-01-01

    For voids in a shear field unit cell model analyses have been used to show that ductile failure is predicted even though the stress triaxiality is low or perhaps negative, so that the void volume fraction does not grow during deformation. Here, the effect of the void shape is studied by analyzing...... with circular cross-section, i.e. the voids in shear flatten out to micro-cracks, which rotate and elongate until interaction with neighboring micro-cracks gives coalescence. Even though the mechanism of ductile failure is the same, the load carrying capacity predicted, for the same initial void volume fraction...

  16. Parameter studies on the effect of pulse shape on the dynamic plastic deformation of a hexagon

    International Nuclear Information System (INIS)

    Youngdahl, C.K.

    1973-10-01

    Results of a parameter study on the dynamic plastic response of a hexagonal subassembly duct subjected to an internal pressure pulse of arbitrary shape are presented. Plastic distortion of the cross section and large-deformation geometric effects that result in redistribution of the internal forces between bending and membrane stresses in the hexagon wall are included in the analytical model. Correlation procedures are established for relating permanent plastic deformation to simple properties of the pressure pulse, for both the small- and large-deformation ranges. Characteristic response times are determined, and the dynamic load factor for large-deformation plastic response is computed

  17. Description of the shape memory effect of radiation-modified polymers under thermomechanical action

    International Nuclear Information System (INIS)

    Chernous, D.A.; Shil'ko, S.V.; Pleskachevskij, Yu.M.

    2004-01-01

    The 'shape memory' effect of crystallizing polymer materials is simulated. The polymer is considered to be an inhomogeneous medium with a moving boundary (temperature-dependent phase composition). Using a model based on the 'frozen strain' hypothesis, the temperature dependences of stresses under isometric heating and cooling have been obtained. On the basis of the known data on the influence of gamma-irradiation on the thermomechanical characteristics the dependences of thermorelaxation and thermoshrinkage stresses on the absorbed dose for high-density polyethylene have been found. (Authors)

  18. Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

    International Nuclear Information System (INIS)

    Xu, Yurun; Chen, Dajun

    2017-01-01

    Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

  19. Self-healing polyurethane/attapulgite nanocomposites based on disulfide bonds and shape memory effect

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yurun; Chen, Dajun, E-mail: cdj@dhu.edu.cn

    2017-07-01

    Nanocomposites with remarkable enhanced mechanical properties have attracted great research efforts recently. In this work, a series of self-healing polyurethane/attapulgite nanocomposites were prepared by solution blending. Introducing self-healing ability and attapulgite (AT) reinforcement simultaneously led to prolonged material lifetime and enhanced mechanical properties. Scanning electron microscope (SEM) observation indicated that AT could achieve a uniform dispersion in polyurethane matrix when AT content was relatively low. The influences on mechanical properties were evaluated by tensile test. Results showed that incorporating an appropriate content of AT would lead to an enhanced tensile properties. The interactions between AT and polyurethane matrix were studied by effective cross-linking density calculation and Fourier transform infrared (FTIR) analysis. Results indicated that rich hydrogen bonds were formed between AT and polyurethane matrix. Displacement data was utilized to evaluate the influence on shape memory effect. With the incorporation of AT, deformation of the sample under external force was restrained. Meanwhile, closure of the scratches still can be accomplished during healing process. Results of healing test suggested that incorporating 1% of AT would also promote self-healing property. - Highlights: • Composites with both self-healing and enhanced mechanical property are prepared. • Healing mechanism relies on disulfide exchange reaction and shape memory effect. • Mechanical enhancement is caused by rich hydrogen bonds introduced by attapulgite.

  20. Effect on Torque and Thrust of the Pointed Tip Shape of a Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Kyoungsoo Lee

    2017-01-01

    Full Text Available This paper presents the effect of the tip shape of a wind turbine blade on aerodynamic forces, including the effects of separation, transition and stall. A National Renewable Energy Laboratory (NREL Phase-VI wind turbine blade was used, in which the shape of the tip was modified to a pointed tip. Computational fluid dynamics (CFD simulations were employed for the analysis and the results were compared with the original NREL blade CFD and experimental data using ANSYS CFX (Ansys Inc., Delaware, PA, USA. To predict the separation and separation-induced transition on both near wall and far away, the shear-stress-transport (SST Gamma-Theta turbulent model was used. The stall onset of a 20° angle of attack and its effects were also analyzed and presented. The value of torque with the pointed tip blade was found to be 3%–8% higher than the original NREL blade showing the benefit of the pointed tip. Normal force coefficient is lower at the tip for the pointed tip blade, which results in lower deformation of the blade. It was found that the pointed-tip blade is more efficient in terms of generating torque than the original NREL Phase-VI blade in the dynamic stall region of 10–15 m/s wind speeds.

  1. A new kind of shape-stabilized PCMs with positive temperature coefficient (PTC) effect

    International Nuclear Information System (INIS)

    Cheng, Wen-long; Wu, Wan-fan; Song, Jia-liang; Liu, Yi; Yuan, Shuai; Liu, Na

    2014-01-01

    Highlights: • A new kind of shape-stabilized PCMs with PTC effect is first prepared. • It provides a potential means for the thermal control of the electronic devices. • The switching temperature of the materials is about 25 °C. • The most appropriate component of the material is found out by experimental study. • The NTC effect of the new PCMs is eliminated effectively by heat treatment. - Abstract: A new kind of shape-stabilized phase change materials (PCMs) with positive temperature coefficient (PTC) effect was prepared in this paper. The materials were prepared by adding graphite powder (GP) to the paraffin/low density polyethylene (LDPE) composite and the PTC characteristic was found by adjusting the component ratio of the material. Then the physical structures and thermal properties of the materials were investigated and the effect of various GP mass fractions and paraffin/LDPE mass proportions on the PTC behavior of the materials was studied experimentally. The results showed that the switching temperature of the materials was about 25 °C (room temperature) which approached to the first phase change temperature of paraffin dispersed in the materials. The PTC behavior of the materials was the best when the GP mass fraction and the mass proportion of LDPE/paraffin were 40 wt% and 30:70, respectively. Furthermore, the negative temperature coefficient (NTC) effect of the materials could be eliminated effectively with heat treatment. This new kind of materials is different from the former PTC materials which the switching temperatures focus on high temperature ranges. It makes up for the defect of previous materials that the switching temperatures only range in high temperature rather than room temperature and provides a potential means for the thermal control of the electronic devices or other room temperature thermal control applications

  2. Effect of Dimension and Shape of Magnet on the Performance AC Generator with Translation Motion

    Science.gov (United States)

    Indriani, A.; Dimas, S.; Hendra

    2018-02-01

    The development of power plants using the renewable energy sources is very rapid. Renewable energy sources used solar energy, wind energy, ocean wave energy and other energy. All of these renewable energy sources require a processing device or a change of motion system to become electrical energy. One processing device is a generator which have work principle of converting motion (mechanical) energy into electrical energy with rotary shaft, blade and other motion components. Generator consists of several types of rotation motion and linear motion (translational). The generator have components such as rotor, stator and anchor. In the rotor and stator having magnet and winding coil as an electric generating part of the electric motion force. Working principle of AC generator with linear motion (translation) also apply the principle of Faraday that is using magnetic induction which change iron magnet to produce magnetic flux. Magnetic flux is captured by the stator to be converted into electrical energy. Linear motion generators consist of linear induction machine, wound synchronous machine field, and permanent magnet synchronous [1]. Performance of synchronous generator of translation motion is influenced by magnet type, magnetic shape, coil winding, magnetic and coil spacing and others. In this paper focus on the neodymium magnet with varying shapes, number of coil windings and gap of magnetic distances. This generator work by using pneumatic mechanism (PLTGL) for power plants system. Result testing of performance AC generator translation motion obtained that maximum voltage, current and power are 63 Volt for diameter winding coil 0.15 mm, number of winding coil 13000 and distance of magnet 20 mm. For effect shape of magnet, maximum voltage happen on rectangle magnet 30x20x5 mm with 4.64 Volt. Voltage and power on effect of diameter winding coil is 14.63 V and 17.82 W at the diameter winding coil 0.7 and number of winding coil is 1260 with the distance of magnet 25

  3. Effects of particle shape and size on nanofluid properties for potential Enhanced Oil Recovery (EOR

    Directory of Open Access Journals (Sweden)

    Tengku Mohd Tengku Amran

    2016-01-01

    Full Text Available Application of Enhanced Oil Recovery (EOR in oil and gas industry is very important to increase oil recovery and prolong the lifetime of a reservoir but it has been very costly and losing properties of EOR agent due to harsh condition. Nanoparticles have been used in EOR application since they are not degradable in reservoir condition and used in smaller amount compared to polymer usage. Commonly, EOR techniques are focusing on increasing the sweep efficiency by controlling the mobility ratio between reservoir fluid and injected fluid. Thus, this research aimed to analyze the nanofluid viscosity at different particle size and shape, volumetric concentration and types of dispersing fluid, as well as to determine the oil recovery performance at different nanofluid concentration. The nanofluid viscosity was investigated at nanoparticle sizes of 15nm and 60nm and shapes of 15nm spherical-solid and porous. Five nanofluid samples with concentration ranging from 0.1wt.% to 7wt.% were used to investigate the effect of volumetric concentration. Distilled water, ethanol, ethylene glycol (EG and brine were used for the effect of dispersing fluids. Oil recovery was investigated at five different concentrations of nanofluid samples through flooding test. It was found that viscosity of nanofluid increased with decreasing particle size and increasing volumetric concentration. Solid shape particle and increasing dispersing fluid viscosity resulted in higher nanofluid viscosity. The higher the nanofluid concentration, the higher the oil recovery obtained. It can be concluded that nanofluid properties have been significantly affected by the environment and the particle used for potential EOR application.

  4. In vitro toxicity analysis of nanoscale aluminum: Particle size and shape effects

    Science.gov (United States)

    Palazuelos Jorganes, Maria

    2007-12-01

    Nanostructured materials promise to revolutionize many key areas of science and technology. As our ability to manipulate matter at the nanoscale increases, there is a need to assess the effects of these materials on human health and the environment. Materials at the nanoscale are interesting and useful because they possess properties that are different from the equivalent bulk or molecular scale. These same properties can make toxicological profiles very different from those of the same materials on a different scale. There is a rising consensus that toxicity analysis of nanomaterials should start from a thorough physicochemical characterization of the materials under investigation in order to be able to establish a proper correlation between the nanoparticles characteristics and their effects and behavior in physiological environments. This research is a clear example of the necessity of comprehensive studies when investigating the toxicity of nanomaterials. Aluminum nanoparticles are being extensively used for their very unique energetic properties. These materials offer a very promising market that is fostering many startup companies which are expected to consolidate on strong technological positions. Aluminum is generally recognized as a non-toxic material to humans and it is widely used for applications which imply direct human contact. The effect of aluminum nanoparticles in human health is still an unknown. My research consisted of an in vitro toxicity screening of aluminum materials from nano to micron size, including spherical irregularly shaped particles. Several issues relating to size, shape, detection and characterization of nanoparticles in the different environments relevant to in vitro toxicity analysis were addressed and suitable protocols were developed. Lung human epithelial cells were exposed to different concentrations of these materials and the effects were analyzed by means of various toxicity tests. Some of the materials investigated caused

  5. Effect of diffuse layer and pore shapes in mesoporous carbon supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Qiao, Rui [ORNL

    2010-01-01

    In the spirit of the theoretical evolution from the Helmholtz model to the Gouy Chapman Stern model for electric double-layer capacitors, we explored the effect of a diffuse layer on the capacitance of mesoporous carbon supercapacitors by solving the Poisson Boltzmann (PB) equation in mesopores of diameters from 2 to 20 nm. To evaluate the effect of pore shape, both slit and cylindrical pores were considered. We found that the diffuse layer does not affect the capacitance significantly. For slit pores, the area-normalized capacitance is nearly independent of pore size, which is not experimentally observed for template carbons. In comparison, for cylindrical pores, PB simulations produce a trend of slightly increasing area-normalized capacitance with pore size, similar to that depicted by the electric double-cylinder capacitor model proposed earlier. These results indicate that it is appropriate to approximate the pore shape of mesoporous carbons as being cylindrical and the electric double-cylinder capacitor model should be used for mesoporous carbons as a replacement of the traditional Helmholtz model.

  6. Numerical Analysis of the Effect of Particle Shape and Adhesion on the Segregation of Powder Mixtures

    Directory of Open Access Journals (Sweden)

    Alizadeh Behjani Mohammadreza

    2017-01-01

    Full Text Available Segregation of granules is an undesired phenomenon in which particles in a mixture separate from each other based on the differences in their physical and chemical properties. It is, therefore, crucial to control the homogeneity of the system by applying appropriate techniques. This requires a fundamental understanding of the underlying mechanisms. In this study, the effect of particle shape and cohesion has been analysed. As a model system prone to segregation, a ternary mixture of particles representing the common ingredients of home washing powders, namely, spray dried detergent powders, tetraacetylethylenediamine, and enzyme placebo (as the minor ingredient during heap formation is modelled numerically by the Discrete Element Method (DEM with an aim to investigate the effect of cohesion/adhesion of the minor components on segregation quality. Non-spherical particle shapes are created in DEM using the clumped-sphere method based on their X-ray tomograms. Experimentally, inter particle adhesion is generated by coating the minor ingredient (enzyme placebo with Polyethylene Glycol 400 (PEG 400. The JKR theory is used to model the cohesion/adhesion of coated enzyme placebo particles in the simulation. Tests are carried out experimentally and simulated numerically by mixing the placebo particles (uncoated and coated with the other ingredients and pouring them in a test box. The simulation and experimental results are compared qualitatively and quantitatively. It is found that coating the minor ingredient in the mixture reduces segregation significantly while the change in flowability of the system is negligible.

  7. The Effect of Void Shape on the Mechanical Properties of Rock

    International Nuclear Information System (INIS)

    D.O. Potyondy

    2006-01-01

    The bonded-particle model for rock (Potyondy and Cundall, 2004) represents rock by a dense packing of non-uniform-sized circular or spherical particles that are bonded together at their contact points and whose mechanical behavior is simulated by the distinct-element method using the two- and three-dimensional programs PFC2D and PFC3D. A bonded-particle model of lithophysal tuff has been used to study the effect of lithophysae (hollow, bubble-like voids) on the mechanical properties (Young's modulus and unconfined compressive strength) of this rock, and to quantify the variability of these properties. The model reproduces the failure mechanisms observed in the laboratory and exhibits a reduction of strength and modulus with increasing lithophysal volume fraction. The effect of void shape on mechanical properties is studied by inserting randomly distributed voids of simple shape (circle, triangle and star) and by inserting voids corresponding with lithophysal cavities identified in panel maps of the walls of a tunnel through this material. These studies address tunnel-stability issues associated with mechanical degradation of planned emplacement drifts at Yucca Mountain, which is the designated site for the proposed US high-level nuclear waste repository

  8. Effects of target shape and impact speed on the outcome of catastrophic disruptions

    Science.gov (United States)

    Campo~Bagatin, A.; Durda, D.; Alemañ, R.; Flynn, G.; Strait, M.; Clayton, A.; Patmore, E.

    2014-07-01

    Because of the propensity of previous laboratory investigations to focus on idealized spherical targets, there is a bit of ambiguity in decoupling the relative importance/influence of low speed or spherical shape in producing the 'onion shell' fragment shape outcomes found in impacts into spherical targets [1,2]. If due primarily to impact speed/energy density as suggested by [3], this could play an important role in main-belt impacts due to the presence of non-spherical targets and non-negligible probability of low-speed (i.e., below about 3-4 km/s, subsonic in rock) impacts [4]. Also, [5] and [6] suggested that the shape of targets may affect the outcome of shattering processes, both in terms of fragment shape and mass distribution. To examine explicitly the effects of target shape in impact outcomes, we chose to conduct impact experiments on both spherical and naturally-occurring irregularly-shaped basalt targets. We impacted a total of six targets (two spheres and four irregular targets). We focused on shots with impact speeds in the ˜4 to 6 km/s range by 3/16th-inch diameter Al-sphere projectiles fired at the NASA AVGR. Following each shot, the debris were recovered (>95 %) and large fragments (>0.20 g) were individually weighed, allowing us to carefully measure the mass-frequency distribution from each impact experiment. The 36 largest fragments of each shot were photographed and their largest axes accurately measured by the program ''ImageJ''. Their shortest axes were measured by means of a digital caliber. High-speed video of each impact was obtained to aid interpretation of the fragmentation mode of the targets. Images clearly show that shell-like fragments can be produced in shattering events not in the target's surface. Instead, those fragments may form around the core, well inside the target structure, independently on the target shape itself. This is a feature not reported to date. In order to understand what the bulk macro-porosity of a non

  9. Improvement of the shape memory effect of a Fe-Mn-Cr-Si-Ni by original thermomechanical treatments

    International Nuclear Information System (INIS)

    Federzoni, L.; Guenin, G.; Mantel, M.

    1993-01-01

    Among the shape memory alloys, Fe-based have real perspectives of industrial development. However, to acquire a good shape memory effect, these alloys must undergo a thermomechanical treatment. For applcation perspective this treatment must be the simpliest as possible. In this paper, two types of treatment have been performed, based of the fact that : - the formation of the martensite ε, responsible for the shape memory effect, is sensitive to the microstructure - its reversibility is the best as possible if the austenite is previously hardened by a deformation at high temperature. (orig.)

  10. Micropore Geometry Manipulation by Macroscopic Deformation Based on Shape Memory Effect in Porous PLLA Membrane and its Enhanced Separation Performance.

    Science.gov (United States)

    Zhao, Jingxin; Yang, Qiucheng; Wang, Tao; Wang, Lian; You, Jichun; Li, Yongjin

    2017-12-20

    An effective strategy to tailor the microporous structures has been developed based on the shape memory effect in porous poly(l-lactic acid) membranes in which tiny crystals and amorphous matrix play the roles of shape-fixed phase and reversible-phase, respectively. Our results indicate that not only PLLA membranes but micropores exhibit shape memory properties. The proportional deformations on two scales have been achieved by uniaxial or biaxial tension, providing a facile way to manipulate continuously the size and the orientation degree of pores on microscale. The enhanced separation performance has been validated by taking polystyrene colloids with varying diameters as an example.

  11. Impact of Grain Shape and Multiple Black Carbon Internal Mixing on Snow Albedo: Parameterization and Radiative Effect Analysis

    Science.gov (United States)

    He, Cenlin; Liou, Kuo-Nan; Takano, Yoshi; Yang, Ping; Qi, Ling; Chen, Fei

    2018-01-01

    We quantify the effects of grain shape and multiple black carbon (BC)-snow internal mixing on snow albedo by explicitly resolving shape and mixing structures. Nonspherical snow grains tend to have higher albedos than spheres with the same effective sizes, while the albedo difference due to shape effects increases with grain size, with up to 0.013 and 0.055 for effective radii of 1,000 μm at visible and near-infrared bands, respectively. BC-snow internal mixing reduces snow albedo at wavelengths external mixing, internal mixing enhances snow albedo reduction by a factor of 1.2-2.0 at visible wavelengths depending on BC concentration and snow shape. The opposite effects on albedo reductions due to snow grain nonsphericity and BC-snow internal mixing point toward a careful investigation of these two factors simultaneously in climate modeling. We further develop parameterizations for snow albedo and its reduction by accounting for grain shape and BC-snow internal/external mixing. Combining the parameterizations with BC-in-snow measurements in China, North America, and the Arctic, we estimate that nonspherical snow grains reduce BC-induced albedo radiative effects by up to 50% compared with spherical grains. Moreover, BC-snow internal mixing enhances the albedo effects by up to 30% (130%) for spherical (nonspherical) grains relative to external mixing. The overall uncertainty induced by snow shape and BC-snow mixing state is about 21-32%.

  12. ''Some features of γ-ε martensitic transformation and shape memory effect in Fe-Mn-Si based alloys''

    International Nuclear Information System (INIS)

    Gulyaev, A.A.

    1995-01-01

    In the present paper several important aspects concerning the shape memory behavior of the ε-martensite in the cost-saving Fe-Mn-Si-based alloys and its application are reported. Some kinetic features of the γ-ε martensitic transformation are discussed. The effects of the composition, volume change induced by the transformation, strength of austenite, temperature of pre strain on the shape memory effect have been investigated. (orig.)

  13. Recognition and use of line drawings by children with severe intellectual disabilities: the effects of color and outline shape.

    Science.gov (United States)

    Stephenson, Jennifer

    2009-03-01

    Communication symbols for students with severe intellectual disabilities often take the form of computer-generated line drawings. This study investigated the effects of the match between color and shape of line drawings and the objects they represented on drawing recognition and use. The match or non-match between color and shape of the objects and drawings did not have an effect on participants' ability to match drawings to objects, or to use drawings to make choices.

  14. Intra-aortic balloon shape change: effects on volume displacement during inflation and deflation.

    Science.gov (United States)

    Khir, Ashraf William; Bruti, Gianpaolo

    2013-07-01

    It has been observed that operating the intra-aortic balloon at an angle to the horizontal resulted in a reduction of the volume displaced toward the coronary arteries and compromised afterload reduction. Therefore, the aim of this work is to examine whether changing the current balloon shape, which has not been altered for 40 years, could compensate for the negative hemodynamic effects due to angulation. We tested two tapered balloons, increasing diameter (TID) and decreasing diameter (TDD), and compared the results with those obtained from a standard cylindrical balloon. The balloons were tested in vitro at 60 beats/min and a static pressure of 90 mm Hg. The balloons were operated at four angles (0°, 20°, 30°, 45°), and the pressure at three locations along the balloon (base, middle, and tip) was also measured. Flow rate upstream of the tip of the balloon was also measured to indicate the flow displaced toward the coronary circulation. The relative volume displaced toward (VUTVi) and suctioned away from (VUTVd) the simulated ascending aorta, during inflation and deflation, respectively, is reduced when a standard cylindrical balloon is operated at an angle to the horizontal. The TDD provided the greatest VUTVi and also produced the largest pulse pressure during deflation. Although the TID provided less VUTVi and VUTVd at smaller angles, it was not markedly affected by the change of angle. According to these results, different balloon shapes analyzed, with comparable volume to that of a cylindrical balloon, produced greater inflation and deflation benefits, at the horizontal and at a range of angles to the horizontal. Further investigations are required to optimize the shape of the tapered balloons to fit into the available physiological space. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

  15. SHAPE EFFECT OF ANNULAR CONCENTRATOR IN ULTRASONIC SYSTEM ON AMPLIFICATION FACTOR OF VIBRATIONS AMPLITUDE

    Directory of Open Access Journals (Sweden)

    D. A. Stepanenko

    2016-01-01

    Full Text Available The paper contains a theoretical underpinning on creation of ultrasonic vibration concentrators based on annular elastic elements with non-circular (ellipse-like eccentric shape of internal contour. Shape of internal contour in polar coordinates is described by Fourier series relative to angular coordinate that consists of a constant term and first and second harmonics. An effect of geometric parameters of the concentrator on amplification factor and natural vibration frequencies has been investigated with the help of a finite element method. The paper reveals the possibility to control an amplification factor of annular concentrators while varying eccentricity of internal contour and mean value of cross-section thickness. The amplification factor satisfies a condition K < N, where N is thickness ratio of amplifier input and output sections, and it is decreasing with increase of vibration mode order. The similar condition has been satisfied for conical bar concentrator with the difference that in the case of bar concentrators an amplification is ensured due to variation of diameter and N will represent ratio of diameters. It has been proved that modification of internal contour shape makes it possible to carry out a wide-band tuning of natural frequencies of concentrator vibrations without alteration of its overall dimensions and substantial change of amplification factor, which is important for frequency matching of the concentrator and ultrasonic vibratory system. Advantages of the proposed concentrators include simplicity of design and manufacturing, small overall dimensions, possibility for natural frequency tuning by means of static load variation. The developed concentrators can find their application in ultrasonic devices and instruments for technological and medical purposes.

  16. Effects of sex, stock, and environment on the shape of known-age Atlantic cod ( Gadus morhua ) otoliths

    DEFF Research Database (Denmark)

    Cardinale, M.; Doering-Arjes, P.; Kastowsky, M.

    2004-01-01

    The effects of sex, stock, and environment on the shape of known-age Atlantic cod (Gadus morhua) otoliths from the Faroe Islands were investigated. Moreover, the feasibility of otolith shape analysis for stock identification was evaluated. The shape was described by using several normalized Fourier...... descriptors and morphometric variables. There were no consistent differences between the left and right otoliths and between sexes within different age classes, stocks, and environments. With our experimental design, we could evaluate the relative importance of genetic and environmental conditions (water...... temperature and diet regime) on otolith shape and morphometrics. Using otolith shape, cod individuals were significantly separated into Bank and Plateau stocks. Total classification success was between 79% and 85% between stocks and between 85% and 96% between environments for the different age classes...

  17. The shape of dose-effect curves for diploid yeast cells irradiated with ionizing particles

    International Nuclear Information System (INIS)

    Pohlit, W.

    1975-01-01

    In a cybernetic model for the radiation reactions in eukaryotic cells, after irradiation they are assumed to be in one of three states: (a) viable cells; (b) with repairable damage; and (c) with irreparable damage. Two biological counter reactions with certain time constants can be observed: (i) recovery from sublethal damage; and (ii) repair of potential lethal damage. The shape of the dose-effect curve is influenced in a characteristic way by the different occupation of these states of the cells and by the time constants of the biological counter reactions. The biochemical analysis of the biological counter reactions, recovery and repair, has shown that both are linked together by the energy pool in the cell. In this way changes in the slope of the dose-effect curve due to different metabolic states of the cells can be understood quantitatively. Also the complicated dependence of survival cells on the absorbed dose rate over a wide range can be explained quantitatively. (author)

  18. Rotator side chains trigger cooperative transition for shape and function memory effect in organic semiconductors.

    Science.gov (United States)

    Chung, Hyunjoong; Dudenko, Dmytro; Zhang, Fengjiao; D'Avino, Gabriele; Ruzié, Christian; Richard, Audrey; Schweicher, Guillaume; Cornil, Jérôme; Beljonne, David; Geerts, Yves; Diao, Ying

    2018-01-18

    Martensitic transition is a solid-state phase transition involving cooperative movement of atoms, mostly studied in metallurgy. The main characteristics are low transition barrier, ultrafast kinetics, and structural reversibility. They are rarely observed in molecular crystals, and hence the origin and mechanism are largely unexplored. Here we report the discovery of martensitic transition in single crystals of two different organic semiconductors. In situ microscopy, single-crystal X-ray diffraction, Raman and nuclear magnetic resonance spectroscopy, and molecular simulations combined indicate that the rotating bulky side chains trigger cooperative transition. Cooperativity enables shape memory effect in single crystals and function memory effect in thin film transistors. We establish a molecular design rule to trigger martensitic transition in organic semiconductors, showing promise for designing next-generation smart multifunctional materials.

  19. Martensitic transformation and shape memory effect in polycomponent TiNi-based alloys

    International Nuclear Information System (INIS)

    Khachin, V.N.; Voronin, V.P.; Sivokha, V.P.; Pushin, V.G.

    1995-01-01

    The results of martesitic transformation (MT) and shape memory effect (SME) in quaternary Ti 50 (NiCoCu) 50 , Ti 50 (NiFeCu) 50 and (TiAl) 50 (NiCu) 50 alloys studies are generalized in this paper. On alloying TiNi simultaneously by two elements, their individual effect on MT and SME is conserved. Martensitic transformations B2→R and B2→B19' are almost simultaneously realizing in a binary TiNi. One can selectively control each of two MT channels by selecting property of alloying elements. As a result, the alloys having any sequences of MT and their realizations temperatures, including simultaneous realization of two MTs at low temperatures, which was not observed earlier, can be produced. (orig.)

  20. Influence of Shape Anisotropy on Magnetization Dynamics Driven by Spin Hall Effect

    Directory of Open Access Journals (Sweden)

    X. G. Li

    2016-01-01

    Full Text Available As the lateral dimension of spin Hall effect based magnetic random-access memory (SHE-RAM devices is scaled down, shape anisotropy has varied influence on both the magnetic field and the current-driven switching characteristics. In this paper, we study such influences on elliptic film nanomagnets and theoretically investigate the switching characteristics for SHE-RAM element with in-plane magnetization. The analytical expressions for critical current density are presented and the results are compared with those obtained from macrospin and micromagnetic simulation. It is found that the key performance indicators for in-plane SHE-RAM, including thermal stability and spin torque efficiency, are highly geometry dependent and can be effectively improved by geometric design.

  1. Chromosomal inversions effect body size and shape in different breeding resources in Drosophila buzzatii.

    Science.gov (United States)

    Fernández Iriarte, P J; Norry, F M; Hasson, E R

    2003-07-01

    The cactophilic Drosophila buzzatii provides an excellent model for the study of reaction norms across discrete environments because it breeds on rotting tissues (rots) of very different cactus species. Here we test the possible effects of second chromosome inversions on body size and shape (wing loading) across suitable natural breeding substrates. Using homokaryotypic stocks derived from several lines homozygous for four naturally occurring chromosomal inversions, we show that arrangements significantly affect size-related traits and wing loading. In addition, karyotypes show differing effects, across natural breeding resources, for wing loading. The 2st and 2jz(3) arrangements decrease and the 2j arrangement increases wing loading. For thorax length and wing loading, karyotypic correlations across host plants are slightly lower in females than in males. These results support the hypothesis that these traits have a genetic basis associated with the inversion polymorphism.

  2. Effect of heat treatment on transformation behavior of Ti-Ni-V shape memory alloy

    International Nuclear Information System (INIS)

    He Zhirong; Liu Manqian

    2011-01-01

    Highlights: → New shape memory alloy (SMA) - Ti-50.8Ni-0.5V SMA. → The evolution laws of transformation types of annealed Ti-50.8Ni-0.5V SMA. → The evolution laws of transformation types of aged Ti-50.8Ni-0.5V SMA. → The effect laws of annealing on transformation temperature and hysteresis of the alloy. → The effect laws of aging on transformation temperature and hysterises of the alloy. - Abstract: Effects of annealing and aging processes on the transformation behaviors of Ti-50.8Ni-0.5V (atomic fraction, %) shape memory alloy were investigated by means of differential scanning calorimetry (DSC). The A → R/R → A (A - parent phase, R - R phase) type one-stage reversible transformation occurs in 350-400 deg. C annealed alloy, the A → R → M/M → R → A (M - martensite) type two-stage transformation occurs in 450-500 deg. C annealed alloy, the A → R → M/M → A type transformation occurs in 550 deg. C annealed alloy, and A → M/M → A type transformation occurs in the alloy annealed at above 600 deg. C upon cooling/heating. The transformation type of 300 deg. C aged alloy is A → R/R → A, and that of 500 deg. C aged alloy is A → R → M/M → A, while that of 400 deg. C aged alloy changes from A → R/R → A to A → R → M/M → R → A with increasing aging time. The effects of annealing and aging processes on R and M transformation temperatures and temperature hysteresis are given. The influence of annealing and aging temperature on transformation behaviors is stronger than that of annealing and aging time.

  3. Improved Functional Properties and Efficiencies of Nitinol Wires Under High-Performance Shape Memory Effect (HP-SME)

    Science.gov (United States)

    Casati, R.; Saghafi, F.; Biffi, C. A.; Vedani, M.; Tuissi, A.

    2017-10-01

    Martensitic Ti-rich NiTi intermetallics are broadly used in various cyclic applications as actuators, which exploit the shape memory effect (SME). Recently, a new approach for exploiting austenitic Ni-rich NiTi shape memory alloys as actuators was proposed and named high-performance shape memory effect (HP-SME). HP-SME is based on thermal recovery of de-twinned martensite produced by mechanical loading of the parent phase. The aim of the manuscript consists in evaluating and comparing the fatigue and actuation properties of austenitic HP-SME wires and conventional martensitic SME wires. The effect of the thermomechanical cycling on the actuation response and the changes in the electrical resistivity of both shape memory materials were studied by performing the actuation tests at different stages of the fatigue life. Finally, the changes in the transition temperatures before and after cycling were also investigated by differential calorimetric tests.

  4. The effects of cold rolling and the subsequent heat treatments on the shape memory and the superelasticity characteristics of Cu73Al16Mn11 shape memory alloy

    Science.gov (United States)

    Babacan, N.; Ma, J.; Turkbas, O. S.; Karaman, I.; Kockar, B.

    2018-01-01

    In the present study, the effect of thermo-mechanical treatments on the shape memory and the superelastic characteristics of Cu73Al16Mn11 (at%) shape memory alloy were investigated. 10%, 50% and 70% cold rolling and subsequent heat treatment processes were conducted to achieve strengthening via grain size refinement. 70% grain size reduction compared to the homogenized condition was obtained using 70% cold rolling and subsequent recrystallization heat treatment technique. Moreover, 10% cold rolling was applied to homogenized specimen to reveal the influence of the low percentage cold rolling reduction with no heat treatment on shape memory properties of Cu73Al16Mn11 (at%) alloy. Stress free transformation temperatures, monotonic tension and superelasticity behaviors of these samples were compared with those of the as-aged sample. Isobaric heating-cooling experiments were also conducted to see the dimensional stability of the samples as a function of applied stress. The 70% grain-refined sample exhibited better dimensional stability showing reduced residual strain levels upon thermal cycling under constant stress compared with the as-aged material. However, no improvement was achieved with grain size reduction in the superelasticity experiments. This distinctive observation was attributed to the difference in the magnitude of the stress levels achieved during two different types of experiments which were the isobaric heating-cooling and superelasticity tests. Intergranular fracture due to the stress concentration overcame the strengthening effect via grain refinement in the superelasticity tests at higher stress values. On the other hand, the strength of the material and resistance of material against plastic deformation upon phase transformation were increased as a result of the grain refinement at lower stress values in the isobaric heating-cooling experiments.

  5. Biomedical engineering in design and application of nitinol stents with shape memory effect

    Science.gov (United States)

    Ryklina, E. P.; Khmelevskaya, I. Y.; Morozova, Tamara V.; Prokoshkin, S. D.

    1996-04-01

    Our studies in the field of endosurgery in collaboration with the physicians of the National Research Center of Surgery of the Academy of Medical Sciences are carried out beginning in 1983. These studies laid the foundation for the new direction of X-ray surgery--X-ray Nitinol stenting of vessels and tubular structures. X-ray nitinol stents are unique self-fixing shells based on the shape memory effect and superelasticity of nickel-titanium alloys self- reconstructed under human body temperature. Applied for stenting of arteries in cases of stenosis etc., bile ducts in cases of benign and malignant stenoses, digestive tract in cases of oesophageal cancer and cervical canal uterus in cases of postsurgical atresiss and strictures of uterine. The purpose of stenting is restoration of the shape of artery or tubular structure by a cylinder frame formation. The especially elaborated original method of stenting allows to avoid the traditional surgical operation, i.e. the stenting is performed without blood, narcosis and surgical knife. The stent to be implanted is transported into the affected zone through the puncture under the X-ray control. Clinical applications of X-ray endovascular stenting has been started in March 1984. During this period nearly 400 operations on stenting have been performed on femoral, iliac, brachio-cephalic, subclavian arteries, bile ducts, tracheas, digestive tract and cervical canal uterus.

  6. Radiation therapy for malignant lid tumor; Effectiveness of racket-shaped lead protector

    Energy Technology Data Exchange (ETDEWEB)

    Totsuka, Seiichi; Itsuno, Hajime (Shinshu Univ., Matsumoto, Nagano (Japan). Faculty of Medicine)

    1991-04-01

    The case of a 42-year-old man with Meibomian gland carcinoma in his right lower lid is reported. The tumor found in the nasal part of the lower lid, was 12 mm x 13 mm in size. First, surgical resection was performed. The pathological diagnosis of the frozen section was 'undifferentiated basal cell epithelioma'. Second, cryotherapy was performed all over the cut surface. Later, the permanent section was pathologically diagnosed as 'undifferentiated Meibomian gland carcinoma'. Total 50 Gy irradiation therapy was therefore performed using a 9 Mev Linac electron beam, 25 x 20 mm field, with a lead protector for the cornea and lens. A lead contact lens did not afford good results because it was too easily shifted on the cornea, owing to its weight. Therefore, we made a racket-shaped lead protector. Fixed well with tape, this protector afforded good protective effect. Three years after treatment, the patient has good visual function, with no recurrence. This racket-shaped lead protector is thought to be useful in radiation therapy for malignant lid tumors. (author).

  7. Effects of particle shape and temperature on compaction of copper powder at micro scale

    Directory of Open Access Journals (Sweden)

    Chang Chao-Cheng

    2017-01-01

    Full Text Available This study investigated the effects of particle shape and temperature on the compaction of copper powder at micro scale. Copper powder particles were compressed inside a cylindrical die cavity with 2 mm diameter to form compacts with about 3 mm height. Two kinds of particle shapes, spherical and dendritic, and two forming temperatures, room temperature and 400 °C, were considered in the experiments. Some of the produced compacts were further sintered at 600 °C. The study also used simple upsetting tests to investigate the characteristics of the deformation of the compacts under compressive stresses. The results showed that the compacts produced at room temperature demonstrated brittle deformations. However, by increasing the forming temperature to 400 °C, ductile deformations have been observed on the compacts of dendritic particles. Furthermore, the sintering treatment resulted in increases in dimensions, decreases in relative density and hardness, and an increase in ductility. It also led to pore growths which have been seen on scanning-electron microscope images. These phenomena were most significant in the dendritic powder compacts which were produced at 400 °C and treated by the sintering process.

  8. Density and Shape Effects in the Acoustic Propulsion of Bimetallic Nanorod Motors.

    Science.gov (United States)

    Ahmed, Suzanne; Wang, Wei; Bai, Lanjun; Gentekos, Dillon T; Hoyos, Mauricio; Mallouk, Thomas E

    2016-04-26

    Bimetallic nanorods are propelled without chemical fuels in megahertz (MHz) acoustic fields, and exhibit similar behaviors to single-metal rods, including autonomous axial propulsion and organization into spinning chains. Shape asymmetry determines the direction of axial movement of bimetallic rods when there is a small difference in density between the two metals. Movement toward the concave end of these rods is inconsistent with a scattering mechanism that we proposed earlier for acoustic propulsion, but is consistent with an acoustic streaming model developed more recently by Nadal and Lauga ( Phys. Fluids 2014 , 26 , 082001 ). Longer rods were slower at constant power, and their speed was proportional to the square of the power density, in agreement with the acoustic streaming model. The streaming model was further supported by a correlation between the disassembly of spinning chains of rods and a sharp decrease in the axial speed of autonomously moving motors within the levitation plane of the cylindrical acoustic cell. However, with bimetallic rods containing metals of different densities, a consistent polarity of motion was observed with the lighter metal end leading. Speed comparisons between single-metal rods of different densities showed that those of lower density are propelled faster. So far, these density effects are not explained in the streaming model. The directionality of bimetallic rods in acoustic fields is intriguing and offers some new possibilities for designing motors in which shape, material, and chemical asymmetry might be combined for enhanced functionality.

  9. Effect of mitral orifice shape on intra-ventricular filling fluid dynamics

    Science.gov (United States)

    Okafor, Ikechukwu; Angirish, Yagna; Yoganathan, Ajit; Santhanakrishnan, Arvind

    2013-11-01

    The natural geometry of the mitral orifice is D-shaped. However, most current designs of prosthetic valves employ O-shaped orifice geometry. The goal of this study was to compare the effect of geometrical modification between the D and O orifice on the intra-ventricular fluid dynamics during diastolic filling. The different mitral orifice geometries were incorporated into an in vitro left heart simulator consisting of a flexible-walled anatomical left ventricle (LV) physical model enclosed in an acrylic housing. Physiological flow rates and pressures were obtained via tuning systemic resistance and compliance elements in the flow loop. A programmable piston pump was used to generate the LV model wall motion. 2D Particle image velocimetry measurements were conducted along multiple longitudinal planes perpendicular to the annulus plane. During peak diastole, the incoming jet width at the LV central plane was smaller for the D-orifice than that of the O-orifice. Further, the core of the vortex ring in the D-orifice was reduced in size compared to that of the O-orifice. The spatiotemporal spreading of the inflow jet as well as the propagation of the vortex ring will be discussed. This study was funded by a grant from the National Heart, Lung and Blood Institute (RO1HL70262).

  10. Shape-Memory Effect and Pseudoelasticity in Fe-Mn-Based Alloys

    Science.gov (United States)

    La Roca, P.; Baruj, A.; Sade, M.

    2017-03-01

    Several Fe-based alloys are being considered as potential candidates for applications which require shape-memory behavior or superelastic properties. The possibility of using fabrication methods which are well known in the steel industry is very attractive and encourages a large amount of research in the field. In the present article, Fe-Mn-based alloys are mainly addressed. On the one hand, attention is paid to the shape-memory effect where the alloys contain (a) a maximum amount of Mn up to around 30 wt%, (b) several possible substitutional elements like Si, Cr, Ni, Co, and Nb and (c) some possible interstitial elements like C. On the other hand, superelastic alloys are analyzed, mainly the Fe-Mn-Al-Ni system discovered a few years ago. The most noticeable properties resulting from the martensitic transformations which are responsible for the mentioned properties, i.e., the fcc-hcp in the first case and the bcc-fcc in the latter are discussed. Selected potential applications are also analyzed.

  11. Effects of adhesion dynamics and substrate compliance on the shape and motility of crawling cells.

    Directory of Open Access Journals (Sweden)

    Falko Ziebert

    Full Text Available Computational modeling of eukaryotic cells moving on substrates is an extraordinarily complex task: many physical processes, such as actin polymerization, action of motors, formation of adhesive contacts concomitant with both substrate deformation and recruitment of actin etc., as well as regulatory pathways are intertwined. Moreover, highly nontrivial cell responses emerge when the substrate becomes deformable and/or heterogeneous. Here we extended a computational model for motile cell fragments, based on an earlier developed phase field approach, to account for explicit dynamics of adhesion site formation, as well as for substrate compliance via an effective elastic spring. Our model displays steady motion vs. stick-slip transitions with concomitant shape oscillations as a function of the actin protrusion rate, the substrate stiffness, and the rates of adhesion. Implementing a step in the substrate's elastic modulus, as well as periodic patterned surfaces exemplified by alternating stripes of high and low adhesiveness, we were able to reproduce the correct motility modes and shape phenomenology found experimentally. We also predict the following nontrivial behavior: the direction of motion of cells can switch from parallel to perpendicular to the stripes as a function of both the adhesion strength and the width ratio of adhesive to non-adhesive stripes.

  12. Effect of Specimen Shape and Size on the Compressive Strength of Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Sudin M.A.S.

    2014-03-01

    Full Text Available Lightweight concrete, in the form of foamed concrete, is a versatile material that primarily consists of a cement based mortar, mixed with at least 20% volume of air. Its dry density is typically below 1600 kg/m3 with a maximum compressive strength of 15MPa. The ASTM standard provision specifies a correction factor for concrete strength of between 14 and 42Mpa, in order to compensate for a reduced strength, when the aspect height-to-diameter ratio of a specimen is less than 2.0. However, the CEB-FIP provision specifically mentions a ratio of 150mm dia. × 300mm cylinder strength to 150 mm cube strength; though, both provision requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength to lightweight concrete (in this case, foamed concrete. The focus of this work is to study the effect of specimen size and shape on the axial compressive strength of concrete. Specimens of various sizes and shapes were cast with square and circular cross-sections i.e., cubes, prisms, and cylinders. Their compression strength behaviours at 7 and 28 days were investigated. The results indicate that, as the CEB-FIP provision specified, even for foamed concrete, 100mm cubes (l/d = 1.0 produce a comparable compressive strength with 100mm dia. × 200mm cylinders (l/d = 2.0.

  13. Thermoelastic martensite and shape memory effect in ductile Cu-Al-Mn alloys

    Science.gov (United States)

    Kainuma, R.; Takahashi, S.; Ishida, K.

    1996-08-01

    Ductile shape memory (SM) alloys of the Cu-AI-Mn system have been developed by controlling the degree of order in the β phase. Additions of Mn to the binary Cu-Al alloy stabilize the β phase and widen the single-phase region to lower temperature and lower Al contents. It is shown that Cu-Al-Mn alloys with low Al contents have either the disordered A2 structure or the ordered L21 structure with a lower degree of order and that they exhibit excellent ductility. The disordered A2 phase martensitically transforms to the disordered Al phase with a high density of twins. The martensite phase formed from the ordered L21 phase has the 18R structure. The SM effect accompanies both the A2 → Al and L21 → 18R martensitic transformations. These alloys exhibit 15 pct strain to failure, 60 to 90 pct rolling reduction without cracking, and 80 to 90 pct recovery from bend test in the martensitic condition. Experimental results on the microstructure, crystal structure, mechanical properties, and shape memory behavior in the ductile Cu-AI-Mn alloys are presented and discussed.

  14. Effects of major geometric variations between intracavitary applications on pear-shaped isodose dimension in cancer of the cervix

    International Nuclear Information System (INIS)

    Kim, R. Y.

    1996-01-01

    PURPOSE: The basic principal of intracavitary brachytherapy for cancer of the cervix is based on specific loading rules to achieve a pear-shaped isodose distribution centered around the cervix. Recently, ICRU Report 38 recommends a dose reference volume for reporting. Our previous studies have confirmed that there is considerable variations of geometry between applications. This study is to evaluate the effect of major geometric variations on pear-shaped isodose dimension in manual afterloading low-dose-rate system. MATERIAL AND METHODS: One hundred orthogonal films of 50 patients with cancer of the cervix (2 applications/patient) were reviewed for comparative measurements of geometric variations between applications. Major geometric variations were found for 13 patients in lengths of tandem, 7 patients in colpostats separation and 16 patients in vaginal packing. The direct measurement of these geometric variations were compared with the three-dimensional measurement of the pear-shaped isodose enclosed by the point A between the two applications. RESULTS: The geometric variations in the width of colpostats separation and length of tandem were directly related to the width and height of the pear-shaped isodose dimension. The geometric relationship between the colpostats and distal tandem had an important effect on the thickness of the pear-shape. In optimization of poor geometry for rectum or bladder wall, high dose volume centered around the cervix is reduced without changing the overall pear-shaped volume due to changing configuration of the pear-shaped isodose. In our selected patients with two applications, variations in vaginal packing had no direct effect on the width and thickness of the pear-shape due to other variables. CONCLUSION: Major geometric variations between applications greatly affect the dimension of the pear-shaped isodose distribution. Optimization of poor geometry is quite limited without compromising the high-dose volume centered around the

  15. The effect of food shape abnormality on purchase intentions in China

    DEFF Research Database (Denmark)

    Loebnitz, Natascha; Grunert, Klaus G

    2015-01-01

    abnormality (normal, moderately abnormal, and extremely abnormal). The results demonstrate that food shape influences purchase intentions; consumers are more likely to purchase normally shaped fruits and vegetables than moderately or extremely abnormally shaped food. However, environmental concern and social......The assumption that consumers prefer cosmetically perfect fruits and vegetables contributes to global food waste, because food retailers refuse to offer abnormally shaped food. This study empirically examines how food shape abnormality affects purchase intentions and how two individual difference...... variables, environmental concern and social trust, might moderate the food shape abnormality–purchase intention relationship for consumers in China. A representative sample of 212 Chinese consumers indicated their purchase intentions for two fruits and two vegetables with varying levels of food shape...

  16. The effects of carbon nanotubes on electroactive shape-memory behaviors of hydro-epoxy/carbon black composite

    International Nuclear Information System (INIS)

    Wei, Kun; Zhu, Guangming; Tang, Yusheng; Liu, Tingting; Li, Ximin

    2012-01-01

    The objective of this work is to characterize the effect of multi-walled carbon nanotubes (MWCNTs) on the thermomechanical, electrical and shape-memory properties of hydro-epoxy/carbon black (CB) composite. The shape-memory hydro-epoxy composite is fabricated by adding MWCNTs and CB into shape-memory hydro-epoxy resin. The total amount of the fillers fixed at 1.9 wt%, five different composites are produced by varying the amount of MWCNTs between 0 and 0.8 wt% and the amount of CB between 1.1 and 1.9 wt%. The thermomechanical properties and shape-memory performance of the composites are studied. These results indicate that the glass transition temperature (Tg) and the storage modulus of the composites increases at first and then decreases as MWCNTs content increases. The shape recovery time decreases at first and then increases slightly as MWCNTs content increases. The composite presents good shape-memory behavior, and the shape recovery ratio is around 100%. Due to the synergic effect of CB and MWCNTs, the volume electrical resistivity of the composite could decrease by adding a small amount of MWCNTs. (paper)

  17. Experimental Study for Effects of the Stud shape of the Core Catcher System

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kyusang; Son, Hong Hyun; Jeong, Uiju; Seo, Gwang Hyeok; Shin, Doyoung; Jeun, Gyoodong; Kim, Sung Joong [Hanyang University, Seoul (Korea, Republic of)

    2015-05-15

    analysis, it was found that installation of studs affects the streamline by partially blocking the channel. In addition, it was observed that stagnant flow exists at the back of the studs. Such disturbances were expected to differ with the shape of the studs. Thus various stud shapes of rectangular, cylinder, and ellipse were investigated. With this preliminary CFD study, flow boiling experiments were designed and conducted to investigate the effects of the different stud shape on the critical heat flux (CHF). The occurrence of the CHF is anticipated at the back side of the stud due to the possible existence of the hot spot driven by the accumulation of the vapors. Final objective is, therefore, to confirm the effect of the core catcher stud on the performance of boiling heat transfer and to assure that the designed core catcher system may work as intended. In this study, CFD simulations for the different stud shapes of the core catcher system were carried out using ANSYS FLUENNT. With this preliminary CFD study, flow boiling experiments were designed. Final objective is to confirm the effect of the core catcher stud on the performance of boiling heat transfer and to assure that the designed core catcher system may work.

  18. On electrostatic acceleration of plasmas with the Hall effect using electrode shaping

    International Nuclear Information System (INIS)

    Wang, Zhehui; Barnes, Cris W.

    2001-01-01

    Resistive magnetohydrodynamics (MHD) is used to model the electromagnetic acceleration of plasmas in coaxial channels. When the Hall effect is considered, the inclusion of resistivity is necessary to obtain physically meaningful solutions. In resistive MHD with the Hall effect, if and only if the electric current and the plasma flow are orthogonal (J·U=0), then there is a conserved quantity, in the form of U 2 /2+w+eΦ/M, along the flow, where U is the flow velocity, Φ is the electric potential, w is the enthalpy, and M is the ion mass. New solutions suggest that in coaxial geometry the Hall effect along the axial plasma flow can be balanced by proper shaping of conducting electrodes, with acceleration then caused by an electrostatic potential drop along the streamlines of the flow. The Hall effect separation of ion and electron flow then just cancels the electrostatic charge separation. Assuming particle ionization increases with energy density in the system, the resulting particle flow rates (J p ) scales with accelerator bias (V bias ) as J p ∝V bias 2 , exceeding the Child--Langmuir limit. The magnitude of the Hall effect (as determined by the Morozov Hall parameter, Ξ, which is defined as the ratio of electric current to particle current) is related to the energy needed for the creation of each ion--electron pair

  19. Two component tungsten powder injection molding – An effective mass production process

    International Nuclear Information System (INIS)

    Antusch, Steffen; Commin, Lorelei; Mueller, Marcus; Piotter, Volker; Weingaertner, Tobias

    2014-01-01

    Tungsten and tungsten-alloys are presently considered to be the most promising materials for plasma facing components for future fusion power plants. The Karlsruhe Institute of Technology (KIT) divertor design concept for the future DEMO power plant is based on modular He-cooled finger units and the development of suitable mass production methods for such parts was needed. A time and cost effective near-net-shape forming process with the advantage of shape complexity, material utilization and high final density is Powder Injection Molding (PIM). This process allows also the joining of two different materials e.g. tungsten with a doped tungsten alloy, without brazing. The complete technological process of 2-Component powder injection molding for tungsten materials and its application on producing real DEMO divertor parts, characterization results of the finished parts e.g. microstructure, hardness, density and joining zone quality are discussed in this contribution

  20. Stabilizing effect of passive conductors with arbitrary shape for positional instabilities

    International Nuclear Information System (INIS)

    Seki, Shogo; Ninomiya, Hiromasa; Yoshida, Hidetoshi

    1983-10-01

    For positional instabilities in the tokamak, the stabilizing index nsub(s) is an adequate parameter to characterize the stabilizing effect produced by several kinds of passive conductors around a plasma column such as vacuum vessel and poloidal field coils. Since a system of passive conductors with arbitrary shape can be involved into multiple L-R circuits, this parameter nsub(s) of those passive conductors is expressed in a simple form by using a method of the eigen mode expansion of multiple L-R circuits. This parameter nsub(s) is very useful to estimate not only a growth rate of positional instability and its feedback stabilization but also an inward shift of plasma column due to a minor disruption. (author)

  1. Effect of the nozzle tip’s geometrical shape on electrospray deposition of organic thin films

    Science.gov (United States)

    Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko

    2017-04-01

    Electrospray deposition (ESD) is a favorable wet fabrication technique for organic thin films. We investigated the effects of the nozzle tip’s geometrical shape on the spraying properties of an organic solution used for ESD. Five types of cylindrical metal nozzles with zero (flat end) to four protrusions at the tips were prepared for depositing a solution of a small-molecule compound, tris(8-hydroxyquinolinato)aluminum (Alq3) solution. We confirmed that the diameter of the deposited droplets and their size dispersion decreased with an increase in the number of protrusions. The area occupation ratio of small droplets with a diameter smaller than 2 µm increased from 21 to 83% as the number of protrusions was increased from zero to four. The surface roughness root mean square of 60-nm-thick Alq3 films substantially improved from 32.5 to 6.8 nm with increasing number of protrusions.

  2. Simulation of three-phase flow and lance height effect on the cavity shape

    Science.gov (United States)

    Dong, Kai; Zhu, Rong; Gao, Wei; Liu, Fu-hai

    2014-06-01

    A three-dimensional computational fluid dynamics (CFD) model was developed to simulate a 150-t top-blown converter. The effect of different lance heights on the cavity shape was investigated using the volume of fluid (VOF) method. Numerical simulation results can reflect the actual molten bath surface waves impinged by the supersonic oxygen jets. With increasing lance height, the cavity depth decreases, and the cavity area, varying like a parabola, increases and then decreases. The cavity area maximizes at the lance height of 1.3 m. Under the three different lance heights simulated in this study, all of the largest impact velocities at the molten bath surface are between 50 m/s and 100 m/s.

  3. Effect of grain size on superelasticity in Fe-Mn-Al-Ni shape memory alloy wire

    Directory of Open Access Journals (Sweden)

    T. Omori

    2013-09-01

    Full Text Available Effects of grain size on superelastic properties in Fe-34Mn-15Al-7.5Ni alloy wires with a ⟨110⟩ fiber-texture were investigated by cyclic tensile tests. It was confirmed that the critical stress for induced martensitic transformation and the superelastic strain are functions of relative grain size d/D (d: mean grain diameter, D: wire diameter, and that the critical stress is proportional to (1–d/D2 as well as in Cu-based shape memory alloys. A large superelastic strain of about 5% was obtained in the specimen with a large relative grain size over d/D = 1.

  4. Martensitic transformation and shape memory effect in Ni54.75Mn13.25Fe7Ga25 ferromagnetic shape memory alloy

    International Nuclear Information System (INIS)

    Wang, H.B.; Sui, J.H.; Liu, C.; Cai, W.

    2008-01-01

    The martensitic transformation and shape memory effect of Ni 54.75 Mn 13.25 Fe 7 Ga 25 (at.%) alloy are studied in the present paper. It is shown that tetragonal martensite with parallel bands substructure transforms to parent phase heated by electron beam. It can be clearly observed that the martensite band becomes smaller and smaller, then transforms to parent phase completely in the end. A large reversible transformation strain, about 1.5%, is obtained in this undeformed polycrystalline alloy due to martensitic transformation and its reverse transformation. This transformation strain is also increased to 1.8% by the external magnetic field. It is believed that the effect of the magnetic field on the preferential orientation of martensitic variants increases the transformation strain

  5. Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

    OpenAIRE

    Chetan Aneja; Amit Handa

    2016-01-01

    In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW) process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases w...

  6. Effect of microstructure on shape memory effect and transformation behavior in an Fe-32Mn-6.5Si alloy

    International Nuclear Information System (INIS)

    Lee, J. Y.; Choi, C. S.; Jee, K. K.; Shin, M. C.; Jang, W. Y.

    1998-01-01

    The objective of this study is to investigate the effect of microstructure and pre-strain on Shape Memory Effect(SME) and transformation behavior in an Fe-32Mn-6.5Si alloy. The alloy was annealed at various temperatures from 600 to 1200 .deg. C for 1 hour to vary microstructure after cold rolling. Shape memory effect and reverse transformation behavior were examined through bending test and TMA after deforming the alloy with various degree of pre-strain. Austenite grain size increases with an increase in heat treatment temperature, except the specimen heat-treated at 600 .deg. C, which remains unrecrystallized. The specimen heat-treated at 600 .deg. C, retaining cold rolling effect, exhibits the best SME due to a high Md temperature. In the recrystallized specimens, the larger grain size, the better SME. As grain size increases, the reverse transformation range becomes shorter, indicating that reverse transformation takes place with less constraint. The better SME in a large grain size can be attributed to the easiness of the reverse transformation

  7. The effect of moisture absorption on the physical properties of polyurethane shape memory polymer foams

    International Nuclear Information System (INIS)

    Yu, Ya-Jen; Hearon, Keith; Maitland, Duncan J; Wilson, Thomas S

    2011-01-01

    The effect of moisture absorption on the glass transition temperature (T g ) and the stress/strain behavior of network polyurethane shape memory polymer (SMP) foams has been investigated. With our ultimate goal of engineering polyurethane SMP foams for use in blood-contacting environments, we have investigated the effects of moisture exposure on the physical properties of polyurethane foams. To the best of our knowledge, this study is the first to investigate the effects of moisture absorption at varying humidity levels (non-immersion and immersion) on the physical properties of polyurethane SMP foams. The SMP foams were exposed to differing humidity levels for varying lengths of time, and they exhibited a maximum water uptake of 8.0% (by mass) after exposure to 100% relative humidity for 96 h. Differential scanning calorimetry results demonstrated that water absorption significantly decreased the T g of the foam, with a maximum water uptake shifting the T g from 67 to 5 °C. Samples that were immersed in water for 96 h and immediately subjected to tensile testing exhibited 100% increases in failure strains and 500% decreases in failure stresses; however, in all cases of time and humidity exposure, the plasticization effect was reversible upon placing moisture-saturated samples in 40% humidity environments for 24 h

  8. Effect of cold rolling on fatigue crack propagation of TiNi/A16061 shape memory composite

    International Nuclear Information System (INIS)

    Lee, Jin Kyung; Lee, Sang Pill; Park, Young Chul; Lee, Kyu Chang; Cho, Youn Ho; Lee, Joon Hyun

    2005-01-01

    TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 Shape Memory Alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with 0%, 3.2%, 5.2% and 7% volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by this method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied

  9. Effect of Inductive Coil Shape on Sensing Performance of Linear Displacement Sensor Using Thin Inductive Coil and Pattern Guide

    Directory of Open Access Journals (Sweden)

    Hiroyuki Wakiwaka

    2011-11-01

    Full Text Available This paper discusses the effect of inductive coil shape on the sensing performance of a linear displacement sensor. The linear displacement sensor consists of a thin type inductive coil with a thin pattern guide, thus being suitable for tiny space applications. The position can be detected by measuring the inductance of the inductive coil. At each position due to the change in inductive coil area facing the pattern guide the value of inductance is different. Therefore, the objective of this research is to study various inductive coil pattern shapes and to propose the pattern that can achieve good sensing performance. Various shapes of meander, triangular type meander, square and circle shape with different turn number of inductive coils are examined in this study. The inductance is measured with the sensor sensitivity and linearity as a performance evaluation parameter of the sensor. In conclusion, each inductive coil shape has its own advantages and disadvantages. For instance, the circle shape inductive coil produces high sensitivity with a low linearity response. Meanwhile, the square shape inductive coil has a medium sensitivity with higher linearity.

  10. Signalling product healthiness through symbolic package cues: Effects of package shape and goal congruence on consumer behaviour.

    Science.gov (United States)

    van Ooijen, Iris; Fransen, Marieke L; Verlegh, Peeter W J; Smit, Edith G

    2017-02-01

    Three studies show that product packaging shape serves as a cue that communicates healthiness of food products. Inspired by embodiment accounts, we show that packaging that simulates a slim body shape acts as a symbolic cue for product healthiness (e.g., low in calories), as opposed to packaging that simulates a wide body shape. Furthermore, we show that the effect of slim package shape on consumer behaviour is goal dependent. Whereas simulation of a slim (vs. wide) body shape increases choice likelihood and product attitude when consumers have a health-relevant shopping goal, packaging shape does not affect these outcomes when consumers have a hedonic shopping goal. In Study 3, we adopt a realistic shopping paradigm using a shelf with authentic products, and find that a slim (as opposed to wide) package shape increases on-shelf product recognition and increases product attitude for healthy products. We discuss results and implications regarding product positioning and the packaging design process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. The MDI-Mediated Lateral Crosslinking of Polyurethane Copolymer and the Impact on Tensile Properties and Shape Memory Effect

    International Nuclear Information System (INIS)

    Chung, Yong Chan; Chung, Hyang Mi; Choi, Jae Won; Chun, Byoung Chul

    2012-01-01

    The maximum stress and strain at break remained high and stable after MDI-mediated crosslinking. Similarly, shape recovery and shape retention tests also showed excellent and reproducible results. The MDI-mediated crosslinking was responsible for the interesting tensile and shape memory results. Therefore, it was demonstrated in this investigation that the allophanate type crosslinking, unlike previous misleading information, was possible under the mild reaction conditions. Polyurethane (PU) has long been investigated due to its excellent mechanical properties, shape memory effect, and biocompatibility, and was grafted with pendant functional groups to tailor the polymer characteristics without affecting their basic structure. Actually, polyethyleneglycol has been grafted to polyurethane to improve biocompatibility in biomedical applications, and low temperature flexibility could be improved by the pendant naphthol group grafted to PU. In the field of shape memory polyurethane, mechanical and shape memory properties could be improved by terminal crosslinking with glycerol, pentaerythritol, and dextrin. Alternatively, a flexible crosslinking method was devised to demonstrate both high mechanical strength and shape recovery

  12. Insight into the Effects of Reinforcement Shape on Achieving Continuous Martensite Transformation in Phase Transforming Matrix Composites

    Science.gov (United States)

    Zhang, Xudong; Ren, Junqiang; Wang, Xiaofei; Zong, Hongxiang; Cui, Lishan; Ding, Xiangdong

    2017-12-01

    A continuous martensite transformation is indispensable for achieving large linear superelasticity and low modulus in phase transforming metal-based composites. However, determining how to accurately condition the residual martensite in a shape memory alloy matrix though the reinforcement shape to achieve continuous martensite transformation has been a challenge. Here, we take the finite element method to perform a comparative study of the effects of nanoinclusion shape on the interaction and martensite phase transformation in this new composite. Two typical samples are compared: one reinforced by metallic nanowires and the other by nanoparticles. We find that the residual martensite within the shape memory alloy matrix after a pretreatment can be tailored by the reinforcement shape. In particular, our results show that the shape memory alloy matrix can retain enough residual martensite phases to achieve continuous martensite transformation in the subsequent loading when the aspect ratio of nanoreinforcement is larger than 20. In contrast, the composites reinforced with spherical or low aspect ratio reinforcement show a typical nonlinear superelasticity as a result of a low stress transfer-induced discontinuous martensite transformation within the shape memory alloy matrix.

  13. Effects of annealing temperature on shape transformation and optical properties of germanium quantum dots

    Science.gov (United States)

    Alireza, Samavati; Othaman, Z.; K. Ghoshal, S.; K. Mustafa, M.

    2015-02-01

    The influences of thermal annealing on the structural and optical features of radio frequency (rf) magnetron sputtered self-assembled Ge quantum dots (QDs) on Si (100) are investigated. Preferentially oriented structures of Ge along the (220) and (111) directions together with peak shift and reduced strain (4.9% to 2.7%) due to post-annealing at 650 °C are discerned from x-ray differaction (XRD) measurement. Atomic force microscopy (AFM) images for both pre-annealed and post-annealed (650 °C) samples reveal pyramidal-shaped QDs (density ˜ 0.26× 1011 cm-2) and dome-shape morphologies with relatively high density ˜ 0.92 × 1011 cm-2, respectively. This shape transformation is attributed to the mechanism of inter-diffusion of Si in Ge interfacial intermixing and strain non-uniformity. The annealing temperature assisted QDs structural evolution is explained using the theory of nucleation and growth kinetics where free energy minimization plays a pivotal role. The observed red-shift ˜ 0.05 eV in addition to the narrowing of the photoluminescence peaks results from thermal annealing, and is related to the effect of quantum confinement. Furthermore, the appearance of a blue-violet emission peak is ascribed to the recombination of the localized electrons in the Ge-QDs/SiO2 or GeOx and holes in the ground state of Ge dots. Raman spectra of both samples exhibit an intense Ge-Ge optical phonon mode which shifts towards higher frequency compared with those of the bulk counterpart. An experimental Raman profile is fitted to the models of phonon confinement and size distribution combined with phonon confinement to estimate the mean dot sizes. A correlation between thermal annealing and modifications of the structural and optical behavior of Ge QDs is established. Tunable growth of Ge QDs with superior properties suitable for optoelectronic applications is demonstrated. Project supported by Ibnu Sina Institute for Fundamental Science Study, Universiti Teknologi Malaysia

  14. Effects of annealing temperature on shape transformation and optical properties of germanium quantum dots

    International Nuclear Information System (INIS)

    Samavati, Alireza; Othaman, Z.; Ghoshal, S. K.; Mustafa, M. K.

    2015-01-01

    The influences of thermal annealing on the structural and optical features of radio frequency (rf) magnetron sputtered self-assembled Ge quantum dots (QDs) on Si (100) are investigated. Preferentially oriented structures of Ge along the (220) and (111) directions together with peak shift and reduced strain (4.9% to 2.7%) due to post-annealing at 650 °C are discerned from x-ray differaction (XRD) measurement. Atomic force microscopy (AFM) images for both pre-annealed and post-annealed (650 °C) samples reveal pyramidal-shaped QDs (density ∼ 0.26× 10 11 cm −2 ) and dome-shape morphologies with relatively high density ∼ 0.92 × 10 11 cm −2 , respectively. This shape transformation is attributed to the mechanism of inter-diffusion of Si in Ge interfacial intermixing and strain non-uniformity. The annealing temperature assisted QDs structural evolution is explained using the theory of nucleation and growth kinetics where free energy minimization plays a pivotal role. The observed red-shift ∼ 0.05 eV in addition to the narrowing of the photoluminescence peaks results from thermal annealing, and is related to the effect of quantum confinement. Furthermore, the appearance of a blue-violet emission peak is ascribed to the recombination of the localized electrons in the Ge-QDs/SiO 2 or GeO x and holes in the ground state of Ge dots. Raman spectra of both samples exhibit an intense Ge–Ge optical phonon mode which shifts towards higher frequency compared with those of the bulk counterpart. An experimental Raman profile is fitted to the models of phonon confinement and size distribution combined with phonon confinement to estimate the mean dot sizes. A correlation between thermal annealing and modifications of the structural and optical behavior of Ge QDs is established. Tunable growth of Ge QDs with superior properties suitable for optoelectronic applications is demonstrated. (paper)

  15. Influence of cold working on deformation behavior and shape memory effect of Ti-Ni-Nb

    International Nuclear Information System (INIS)

    Okita, K.; Semba, H.; Okabe, N.; Sakuma, T.; Mihara, Y.

    2005-01-01

    In this study, the influence of cold working on the deformation behavior and the transformation characteristics was investigated on the Ti-Ni-Nb shape memory alloy (SMA). Both the tensile test and the shape recovery test were performed for the wire specimens of 1mm in the diameter with some different rates of cold working. The shape recovery tests were performed for the wire specimens of different cold working rates until the various levels of maximum applied strain, and the reverse-transformation characteristics on the process of heating after unloading were studied. It is clarified that the higher cold-working rate improves the shape memory properties of the alloy. (orig.)

  16. Investigation on the corner effect of L-shaped tunneling field-effect transistors and their fabrication method.

    Science.gov (United States)

    Kim, Sang Wan; Choi, Woo Young; Sun, Min-Chul; Park, Byung-Gook

    2013-09-01

    In this work, electrical characteristics of L-shaped tunneling field-effect transistors (TFETs) have been studied and optimized by a commercial device simulator: Synopsys Sentaurus. Unlike our previous study performed by using Silvaco Atlas, there exists a kink phenomenon in a transfer curve which degrades the subthreshold swing (SS) and on-current (lon) of TFETs. According to simulation results, the kink results from abrupt source doping. Rounding the source junction edge with gradual doping profile is helpful to alleviate it. Based on those results, a novel fabrication flow has been proposed to suppress the kink effect induced by source corners. It is predicted that the performance of L-shaped TFETs is improved in terms of SS and Ion under the optimized process condition. Furthremore, the effect of high-k gate dielectric and narrow band gap material on device performance has been examined. Using 2-nm-thick HfO2 for gate dielectric and Si0.7Ge0.3 for intrinsic tunneling region, gate controllability to the channel and tunneling probability have been enhanced. As a result, its threshold voltage (Vth), SS and Ion have been improved by 0.13 V, 16 mV/dec, and 3.62 microA/microm, respectively.

  17. Algebraic solutions of shape-invariant position-dependent effective mass systems

    Energy Technology Data Exchange (ETDEWEB)

    Amir, Naila, E-mail: naila.amir@live.com, E-mail: naila.amir@seecs.edu.pk [School of Electrical Engineering and Computer Sciences, National University of Sciences and Technology, Islamabad (Pakistan); Iqbal, Shahid, E-mail: sic80@hotmail.com, E-mail: siqbal@sns.nust.edu.pk [School of Natural Sciences, National University of Sciences and Technology, Islamabad (Pakistan)

    2016-06-15

    Keeping in view the ordering ambiguity that arises due to the presence of position-dependent effective mass in the kinetic energy term of the Hamiltonian, a general scheme for obtaining algebraic solutions of quantum mechanical systems with position-dependent effective mass is discussed. We quantize the Hamiltonian of the pertaining system by using symmetric ordering of the operators concerning momentum and the spatially varying mass, initially proposed by von Roos and Lévy-Leblond. The algebraic method, used to obtain the solutions, is based on the concepts of supersymmetric quantum mechanics and shape invariance. In order to exemplify the general formalism a class of non-linear oscillators has been considered. This class includes the particular example of a one-dimensional oscillator with different position-dependent effective mass profiles. Explicit expressions for the eigenenergies and eigenfunctions in terms of generalized Hermite polynomials are presented. Moreover, properties of these modified Hermite polynomials, like existence of generating function and recurrence relations among the polynomials have also been studied. Furthermore, it has been shown that in the harmonic limit, all the results for the linear harmonic oscillator are recovered.

  18. Effect of Weld Bead Shape on the Fatigue Behavior of GMAW Lap Fillet Joint in GA 590 MPa Steel Sheets

    Directory of Open Access Journals (Sweden)

    Insung Hwang

    2017-09-01

    Full Text Available In this study, the effect of weld bead shape on the fatigue strength of lap fillet joints using the gas metal arc welding (GMAW process was investigated. The base material used in the experiment was 590 MPa grade galvanealed steel sheet with 2.3 mm and 2.6 mm thickness. In order to make the four types of weld beads with different shapes by factors such as length, angle, and area, the welding process, wire feeding speed, and joint shape were changed. The stress-number of cycles to failure (S–N curve and fatigue strength were obtained from the fatigue test for four types of weld bead, and the cause of the fatigue strength difference was clarified through the analysis of the geometrical factors, such as length, angle, and area of the weld bead. In addition, the relationship between weld bead shape and fatigue strength was discussed.

  19. Effect of impact angles on ejecta and crater shape of aluminum alloy 6061-T6 targets in hypervelocity impacts

    Directory of Open Access Journals (Sweden)

    Hayashi K.

    2012-08-01

    Full Text Available The effect of the impact angle of projectiles on the crater shape and ejecta in thick aluminum alloy targets was investigated in hypervelocity impacts. When polycarbonate projectiles and aluminum alloy 6061-T6 target were used, the impact angle of the projectiles clearly affected the crater shape, as expected. The impact angle also affected the ejecta mass, ejecta size and scatter angle. However, the effect at 15∘ and 22.5∘ was not great. When the impact angles were 30∘ and 45∘, the effect was clearly confirmed. The impact angle clearly affected the axial ratio of ejecta fragments, c/a.

  20. Shape-Memory Effects in Biopolymer Networks with Collagen-Like Transient Nodes

    NARCIS (Netherlands)

    Skrzeszewska, P.J.; Jong, L.N.; Wolf, de F.A.; Stuart, M.A.C.; Gucht, van der J.

    2011-01-01

    In this article we study shape-memory behavior of hydrogels, formed by biodegradable and biocompatible recombinant telechelic polypeptides, with collagen-like end blocks and a random coil-like middle block. The programmed shape of these hydrogels was achieved by chemical cross-linking of lysine

  1. The Effects of Verbal Instruction and Shaping to Improve Tackling by High School Football Players

    Science.gov (United States)

    Harrison, Antonio M.; Pyles, David A.

    2013-01-01

    We evaluated verbal instruction and shaping using TAG (teaching with acoustical guidance) to improve tackling by 3 high school football players. Verbal instruction and shaping improved tackling for all 3 participants. In addition, performance was maintained as participants moved more quickly through the tackling procedure.

  2. Study on the effect of shape-stabilized phase change materials on spacecraft thermal control in extreme thermal environment

    International Nuclear Information System (INIS)

    Wu, Wan-fan; Liu, Na; Cheng, Wen-long; Liu, Yi

    2013-01-01

    Highlights: ► A shape-stabilized PCM is used to protect the spacecraft attacked by high energy. ► Taking a satellite as example, it proves the solution given in the work is feasible. ► Low thermal conductivity makes the material above its thermal stability limit. ► It provides guidance on how to choose the shape-stabilized PCM for similar problems. - Abstract: In space, the emergencies such as short-term high heat flux is prone to cause spacecraft thermal control system faults, resulting in temperature anomalies of electronic equipment of the spacecraft and even failures in them. In order to protect the spacecraft attacked by the high energy, a new guard method is proposed. A shape-stabilized phase change material (PCM), which has high thermal conductivity and does not require being tightly packaged, is proposed to be used on the spacecraft. To prove the feasibility of using the material on spacecraft attacked by high energy, the thermal responses for spacecraft with shape-stabilized PCM are investigated in situations of normal and short-term high heat flux, in contrast to that with conventional thermal control system. The results indicate that the shape-stabilized PCM can effectively absorb the heat to prevent the thermal control system faults when the spacecraft’s outer heat flux changes dramatically and has no negative effect on spacecraft in normal heat flux. Additionally the effect of thermal conductivity of PCM on its application effectiveness is discussed

  3. Effects of collisions on linear and non-linear spectroscopic line shapes

    International Nuclear Information System (INIS)

    Berman, P.R.

    1978-01-01

    A fundamental physical problem is the determination of atom-atom, atom-molecule and molecule-molecule differential and total scattering cross sections. In this work, a technique for studying atomic and molecular collisions using spectroscopic line shape analysis is discussed. Collisions occurring within an atomic or molecular sample influence the sample's absorptive or emissive properties. Consequently the line shapes associated with the linear or non-linear absorption of external fields by an atomic system reflect the collisional processes occurring in the gas. Explicit line shape expressions are derived characterizing linear or saturated absorption by two-or three-level 'active' atoms which are undergoing collisions with perturber atoms. The line shapes may be broadened, shifted, narrowed, or distorted as a result of collisions which may be 'phase-interrupting' or 'velocity-changing' in nature. Systematic line shape studies can be used to obtain information on both the differential and total active atom-perturber scattering cross sections. (Auth.)

  4. Effect of ageing temperatures on pseudoelasticity of Ni-rich NiTi shape memory alloy

    Science.gov (United States)

    Mohamad, Hishamiakim; Mahmud, Abdus Samad; Nashrudin, Muhammad Naqib; Razali, Muhammad Fauzinizam

    2018-05-01

    The shape memory behavior of NiTi alloy is very sensitive to alloy composition and heat treatments, particularly annealing and ageing. This paper analysed the effect of ageing towards the thermomechanical behaviour of Ti-51at%Ni wire. The analysis focused on the effect of ageing at the different temperature on thermal transformation sequence and tensile deformation behaviour with respect to the recoverability of the alloy. It was found that B2-R transformation peak appeared in the differential scanning calorimetry (DSC) measurement when the alloys were aged at the temperature between 400°C to 475°C for 30 minutes. Further ageing at 500°C to 550°C yielded two stage transformation, B2-R-B19' in cooling. All aged wires exhibited good pseudoelastic behaviour when deformed at room temperature and yielded below 1% residual strain upon unloading. Ageing at 450°C resulted the smallest unrecovered strain of about 0.4%.

  5. Effects of Angle of Rotation on Pool Boiling Heat Transfer of V-shape Tube Bundle

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Myeong-Gie [Andong National University, Andong (Korea, Republic of)

    2016-10-15

    The most important facility for the systems is a passive heat exchanger that transfers core decay heat to the cold water in a water storage tank under atmospheric pressure. Since the space for the installation of the heat exchanger is usually limited, developing more efficient heat exchangers is important. In general, pool boiling is generated on the surface of the heat exchanging tube. The major design parameter of the heat exchanger is a tube arrangement. The upper tube is affected by the lower tube and the enhancement of the heat transfer on the upper tube is estimated by the bundle effect. Since heat transfer is related to the conditions of a tube surface, bundle geometries, and a liquid type, lots of studies have been carried out for the combinations of those parameters. An experimental study was performed to investigate the effects of the angle of rotation on pool boiling heat transfer of a V-shape tube bundle. For the test, two smooth stainless steel tubes of 19 mm outside diameter and the water at atmospheric pressure were used. The enhancement of the heat transfer is clearly observed when the angle becomes to 90° where the upper tube has the maximum region of influence by the lower tube. The convective flow and liquid agitation enhance heat transfer while the coalescence of the bubbles deteriorates heat transfer.

  6. Effectiveness of a Constructivistic Multimedia-Learning Package on Shaping and Guiding Students' Attitudes Toward Physics

    Directory of Open Access Journals (Sweden)

    Divya C. Senan

    2016-06-01

    Full Text Available Physics is considered by some to be the most perplexing area in the sciences and perceived as a hard subject for students from secondary school to the university to adult-graduate education. Educational research has provided evidence that attitudes towards physics change with exposure to it. When students have negative attitudes towards physics, they often do not "like" physics courses or the teachers of those courses. Based on this premise, numerous studies have been conducted to determine the factors that affect students' attitudes towards physics. A goal that is important to most if not all teachers of physics courses is to inspire students to have a positive attitude towards the subject. This goal encompasses an appreciation of how physicists think and how they incorporate the values that it provides, as well as, how it is applied to other areas or related fields, and its application in everyday life. In this regard, the aim of this investigation has been to explore how to impact more effectively positive students' attitudes in physics courses. To that end, we report the effectiveness of a constructivistic multimedia-learning package (MLP in shaping and guiding students' attitudes towards physics.

  7. How Online Peer-to-Peer Conversation Shapes the Effects of a Message About Healthy Sleep.

    Science.gov (United States)

    Robbins, Rebecca; Niederdeppe, Jeff

    2017-02-01

    Conversation about health messages and campaigns is common, and message-related conversations are increasingly recognized as a consequential factor in shaping message effects. The evidence base is limited, however, about the conditions under which conversation may help or hinder health communication efforts. In this study, college students (N = 301) first watched a short sleep video and were randomly assigned to either talk with a partner in an online chat conversation or proceed directly to a short survey. Unknown to participants, the chat partner was a confederate coached to say positive things about sleep and the message ('positive' chat condition), negative things ('negative' chat condition), or unrelated things ('natural' chat condition). All respondents completed a short survey on beliefs about sleep, reactions to the message, and intentions to get adequate sleep. Respondents had greater intentions to engage in healthy sleep when they engaged in positive conversation following message exposure than when they engaged in negative conversation after the message (p chat perceptions were significant predictors (p < 0.05) of intentions to achieve healthy sleep. Health message designers may benefit from understanding how messages are exchanged in peer-to-peer conversation to better predict and explain their effects.

  8. Tribological properties of multifunctional coatings with Shape Memory Effect in abrasive wear

    Science.gov (United States)

    Blednova, Zh. M.; Dmitrenko, D. V.; Balaev, E. U. O.

    2018-01-01

    The article gives research results of the abrasive wear process on samples made of Steel 1045, U10 and with applied composite surface layer "Nickel-Multicomponent material with Shape Memory Effect (SME) based on TiNi". For the tests we have chosen TiNiZr, which is in the martensite state and TiNiHfCu, which is in the austenitic state at the test temperature. The formation of the surface layer was carried out by high-speed oxygen-fuel deposition in a protective atmosphere of argon. In the wear test, Al2O3 corundum powder was used as an abrasive. It is shown that the wear rate of samples with a composite surface layer of multicomponent materials with SME is significantly reduced in comparison with the base, which is explained by reversible phase transformations of the surface layer with SME. After carrying out the additional surface plastic deformation (SPD), the resistance of the laminated composition to abrasion wear has greatly enhanced, due to the reinforcing effect of the SPD. It is recommended for products working in conditions of abrasive wear and high temperatures to use the complex formation technology of the surface composition "steel-nickel-material with high-temperature SME", including preparation of the substrate surface and the deposited material, high-speed spraying in the protective atmosphere of argon, followed by SPD.

  9. Effect of antimony incorporation on the density, shape, and luminescence of InAs quantum dots

    Science.gov (United States)

    Chen, J. F.; Chiang, C. H.; Wu, Y. H.; Chang, L.; Chi, J. Y.

    2008-07-01

    This work investigates the surfactant effect on exposed and buried InAs quantum dots (QDs) by incorporating Sb into the QD layers with various Sb beam equivalent pressures (BEPs). Secondary ion mass spectroscopy shows the presence of Sb in the exposed and buried QD layers with the Sb intensity in the exposed layer substantially exceeding that in the buried layer. Incorporating Sb can reduce the density of the exposed QDs by more than two orders of magnitude. However, a high Sb BEP yields a surface morphology with a regular periodic structure of ellipsoid terraces. A good room-temperature photoluminescence (PL) at ˜1600 nm from the exposed QDs is observed, suggesting that the Sb incorporation probably improves the emission efficiency by reducing the surface recombination velocity at the surface of the exposed QDs. Increasing Sb BEP causes a blueshift of the emission from the exposed QDs due to a reduction in the dot height as suggested by atomic force microscopy. Increasing Sb BEP can also blueshift the ˜1300 nm emission from the buried QDs by decreasing the dot height. However, a high Sb BEP yields a quantum well-like PL feature formed by the clustering of the buried QDs into an undulated planar layer. These results indicate a marked Sb surfactant effect that can be used to control the density, shape, and luminescence of the exposed and buried QDs.

  10. Effect of tellurium on machinability and mechanical property of CuAlMnZn shape memory alloy

    International Nuclear Information System (INIS)

    Liu Na; Li Zhou; Xu Genying; Feng Ze; Gong Shu; Zhu Lilong; Liang Shuquan

    2011-01-01

    Highlights: → A novel free-machining Cu-7.5Al-9.7Mn-3.4Zn-0.3Te (wt.%) shape memory alloy has been developed. → The size of dispersed particles with richer Te is 2-5 μm. → The CuAlMnZnTe alloy has good machinability which approached that of BZn15-24-1.5 due to the addition of Te. → Its shape memory property keeps the same as that of CuAlMnZn alloy with free Te. → The CuAlMnZn shape memory alloy with and without Te both have good ductile as annealed at 700 deg. C for 15 min. - Abstract: The microstructure transition, shape memory effect, machinability and mechanical property of the CuAlMnZn alloy with and without Te have been studied using X-ray diffraction analysis, chips observation and scanning electron microscopy (SEM), tensile strength test and differential scanning calorimeter (DSC), and semi-quantitative shape memory effect (SME) test. The particles with richer Te dispersedly distributed in grain interior and boundary with size of 2-5 μm. After the addition of Te, the CuAlMnZnTe alloy machinability has been effectively increased to approach that of BZn15-24-1.5 and its shape memory property remains the same as the one of CuAlMnZn alloy. The CuAlMnZn shape memory alloys with and without Te both have good ductility as annealed at 700 deg. C for 15 min.

  11. Effect of variation in equilibrium shape on ELMing H-mode performance in DIII-D diverted plasmas

    International Nuclear Information System (INIS)

    Fenstermacher, M.E.; Osborne, T.H.; Petrie, T.W.

    2001-01-01

    The changes in the performance of the core, pedestal, scrape-off-layer (SOL), and divertor plasmas as a result of changes in triangularity, δ, up/down magnetic balance, and secondary divertor volume were examined in shape variation experiments using ELMing H mode plasmas on DIII-D. In moderate density, unpumped plasmas, high δ∼0.7 increased the energy in the H mode pedestal and the global energy confinement of the core, primarily due to an increase in the margin by which the edge pressure gradient exceeded the value which would have been expected had it been limited by infinite-n ideal ballooning modes. In addition, a nearly balanced double-null (DN) shape was effective for sharing the peak heat flux in the divertor in these attached plasmas. For detached plasmas good heat flux sharing was obtained for a substantial range of unbalanced DN shapes. Finally, the presence of a second X-point in unbalanced DN shapes did not degrade the plasma performance if it was sufficiently far inside the vacuum vessel. These results indicate that a high δ unbalanced DN shape has some advantages over a single null shape for future high power tokamak operation. (author)

  12. Effect of W Contents on Martensitic Transformation and Shape Memory Effect in Co-Al-W Alloys

    Science.gov (United States)

    Yang, X.; Qian, B. N.; Peng, H. B.; Wu, B. J.; Wen, Y. H.

    2018-04-01

    To clarify the effect of W contents on the shape memory effect (SME) in the Co-Al alloys and its influencing mechanism, the SME, martensitic transformation, and deformation behavior were studied in the Co-7Al-xW ( x = 0, 4, 6, 9 wt pct) alloys. The results showed that the additions of W all deteriorated the SME in Co-7Al alloy when deformed at room temperature. However, when deformed in liquid nitrogen, the SME in Co-7Al alloy could be remarkably improved from 43 to 78 pct after the addition of 4 pct W, above which the SME decreased rapidly with the increase of W content although the yield strength of the parent phase rose due to the solution strengthening of W. The deterioration in SME induced by the excessive addition of W could be ascribed to its resulting significant drop of the start temperature of martensitic transformation.

  13. Effect of in vitro degradation of poly(D,L-lactide)/beta-tricalcium composite on its shape-memory properties.

    Science.gov (United States)

    Zheng, Xiaotong; Zhou, Shaobing; Yu, Xiongjun; Li, Xiaohong; Feng, Bo; Qu, Shuxin; Weng, Jie

    2008-07-01

    The in vitro degradation characteristic and shape-memory properties of poly(D,L-lactide) (PDLLA)/beta-tricalcium phosphate (beta-TCP) composites were investigated because of their wide application in biomedical fields. In this article, PDLLA and crystalline beta-TCP were compounded and interesting shape-memory behaviors of the composite were first investigated. Then, in vitro degradation of the PDLLA/beta-TCP composites with weight ratios of 1:1, 2:1, and 3:1 was performed in phosphate buffer saline solution (PBS) (154 mM, pH 7.4) at 37 degrees C. The effect of in vitro degradation time for PDLLA/beta-TCP composites on shape-memory properties was studied by scanning electron microscopy, differential scanning calorimetry, gel permeation chromatography, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The changes of structural morphology, glass transition temperature (T(g)), molecular weight, and weight loss of composites matrix and pH change of degradation medium indicated that shape-memory effects at different degradation time were nonlinearly influenced because of the breaking down of polymer chain and the formation of degradation products. Furthermore, the results from XRD and FTIR implied that the degradation products, for example, hydroxyapatite (HA), calcium hydrogen phosphate (CaHPO(4)), and calcium pyrophosphate (Ca(2)P(2)O(7)) phases also had some effects on shape-memory properties during the degradation. 2007 Wiley Periodicals, Inc.

  14. Memory color of natural familiar objects: effects of surface texture and 3-D shape.

    Science.gov (United States)

    Vurro, Milena; Ling, Yazhu; Hurlbert, Anya C

    2013-06-28

    Natural objects typically possess characteristic contours, chromatic surface textures, and three-dimensional shapes. These diagnostic features aid object recognition, as does memory color, the color most associated in memory with a particular object. Here we aim to determine whether polychromatic surface texture, 3-D shape, and contour diagnosticity improve memory color for familiar objects, separately and in combination. We use solid three-dimensional familiar objects rendered with their natural texture, which participants adjust in real time to match their memory color for the object. We analyze mean, accuracy, and precision of the memory color settings relative to the natural color of the objects under the same conditions. We find that in all conditions, memory colors deviate slightly but significantly in the same direction from the natural color. Surface polychromaticity, shape diagnosticity, and three dimensionality each improve memory color accuracy, relative to uniformly colored, generic, or two-dimensional shapes, respectively. Shape diagnosticity improves the precision of memory color also, and there is a trend for polychromaticity to do so as well. Differently from other studies, we find that the object contour alone also improves memory color. Thus, enhancing the naturalness of the stimulus, in terms of either surface or shape properties, enhances the accuracy and precision of memory color. The results support the hypothesis that memory color representations are polychromatic and are synergistically linked with diagnostic shape representations.

  15. Experimental study and theoretical simulation of the cross hardening effect in shape memory alloys

    Science.gov (United States)

    Movchan, A. A.; Sil'chenko, A. L.; Kazarina, S. A.

    2017-10-01

    The shapes and the relative position of martensitic inelasticity and forward transformation diagrams are experimentally studied. The strain dependences of the stress in loading under martensitic inelasticity conditions after an experiment on the accumulation of the forward transformation-induced strain at a constant or variable stress are investigated on titanium nickelide samples. It is found that the hardening of the martensite part of the representative volume of a shape memory alloy (titanium nickelide) after forward transformation under a nonmonotonically changing stress can be nonuniform. The cross hardening phenomenon is theoretically described in terms of the model of nonlinear deformation of a shape memory alloy during phase and structural transformations.

  16. Modeling size effects on the transformation behavior of shape memory alloy micropillars

    International Nuclear Information System (INIS)

    Hernandez, Edwin A Peraza; Lagoudas, Dimitris C

    2015-01-01

    The size dependence of the thermomechanical response of shape memory alloys (SMAs) at the micro and nano-scales has gained increasing attention in the engineering community due to existing and potential uses of SMAs as solid-state actuators and components for energy dissipation in small scale devices. Particularly, their recent uses in microelectromechanical systems (MEMS) have made SMAs attractive options as active materials in small scale devices. One factor limiting further application, however, is the inability to effectively and efficiently model the observed size dependence of the SMA behavior for engineering applications. Therefore, in this work, a constitutive model for the size-dependent behavior of SMAs is proposed. Experimental observations are used to motivate the extension of an existing thermomechanical constitutive model for SMAs to account for the scale effects. It is proposed that such effects can be captured via characteristic length dependent material parameters in a power-law manner. The size dependence of the transformation behavior of NiFeGa micropillars is investigated in detail and used as model prediction cases. The constitutive model is implemented in a finite element framework and used to simulate and predict the response of SMA micropillars with different sizes. The results show a good agreement with experimental data. A parametric study performed using the calibrated model shows that the influence of micropillar aspect ratio and taper angle on the compression response is significantly smaller than that of the micropillar average diameter. It is concluded that the model is able to capture the size dependent transformation response of the SMA micropillars. In addition, the simplicity of the calibration and implementation of the proposed model make it practical for the design and numerical analysis of small scale SMA components that exhibit size dependent responses. (paper)

  17. Radiation characteristics and effective optical properties of dumbbell-shaped cyanobacterium Synechocystis sp

    International Nuclear Information System (INIS)

    Heng, Ri-Liang; Pilon, Laurent

    2016-01-01

    dumbbell shape. • An inverse method was developed to retrieve its effective complex index of refraction. • The method was numerically validated for suspensions of bispheres and quadspheres.

  18. Effective Bug Finding in C Programs with Shape and Effect Abstractions

    DEFF Research Database (Denmark)

    Abal, Iago; Brabrand, Claus; Wasowski, Andrzej

    2017-01-01

    Software projects tend to suffer from conceptually simple resource manipulation bugs, such as accessing a de-allocated memory region, or acquiring a non-reentrant lock twice. Static code scanners are used extensively to remove these bugs from projects like the Linux kernel. Yet, when the manipula......Software projects tend to suffer from conceptually simple resource manipulation bugs, such as accessing a de-allocated memory region, or acquiring a non-reentrant lock twice. Static code scanners are used extensively to remove these bugs from projects like the Linux kernel. Yet, when...... the Linux kernel. Our results show that our tool is more effective at finding bugs than similar code-scanning tools. EBA analyzes the drivers/ directory of Linux (nine thousand files) in less than thirty minutes, and uncovers a handful previously unknown double-lock bugs in various drivers....

  19. Numerical investigation on effect of blade shape for stream water wheel performance.

    Science.gov (United States)

    Yah, N. F.; Oumer, A. N.; Aziz, A. A.; Sahat, I. M.

    2018-04-01

    Stream water wheels are one of the oldest and commonly used types of wheels for the production of energy. Moreover, they are economical, efficient and sustainable. However, few amounts of research works are available in the open literature. This paper aims to develop numerical model for investigation of the effect of blade shape on the performance of stream water wheel. The numerical model was simulated using Computational Fluid Dynamics (CFD) method and the developed model was validated by comparing the simulation results with experimental data obtained from literature. The performance of straight, curved type 1 and curved type 2 was observed and the power generated by each blade design was identified. The inlet velocity was set to 0.3 m/s static pressure outlet. The obtained results indicate that the highest power was generated by the Curved type 2 compared to straight blade and curved type 1. From the CFD result, Curved type 1 was able to generate 0.073 Watt while Curved type 2 generate 0.064 Watt. The result obtained were consistent with the experiment result hence can be used the numerical model as a guide to numerically predict the water wheel performance

  20. The Analysis for the Effect of Mixing Vane Shape on TDC

    International Nuclear Information System (INIS)

    Moon, Kang Hoon; Park, Ho Young; Kim, Kang Hoon; Park, Eung Jun; Suh, Jung Min

    2011-01-01

    The Thermal Diffusion Coefficient (TDC) is an input parameter to subchannel code, and it is required to predict local flow conditions in a PWR fuel bundle. TDC influences on the prediction of thermal interchange or mixing of thermal energy between the hot subchannel and interconnected adjacent subchannels. The thermal mixing term in the energy equation is generally represented in terms of a non-dimensional inverse Peclet number or TDC. The parameters associated with thermal mixing can be defined as Eq.(1): TDC =Pe x De/a (1) where: Pe : Inverse Peclet Number (dimensionless) = ε/ Va De : Equivalent hydraulic diameter, in. a : Lateral flow area between channels per unit length, in 2 /in ε : Mixing coefficient, in 2 /sec V : Velocity, in/sec TDC is an important factor to evaluate thermal performance. So, flow temperature maps were obtained from the 5x5 rod bundle test section to assess the thermal performance of corresponding fuels. The flow temperatures were measured by thermocouple at the end of heated length and the centroid of subchannel. There are two typical methods to arrange the hot and cold fuel rods as shown in Fig. 1. Configuration Fig. 1(b) is adopted in this work. This paper presents how to determine the TDC and verifies whether all TDC with the effect of mixing vane shape is valid with respect to current design value

  1. The elastocaloric effect of Ni50.8Ti49.2 shape memory alloys

    Science.gov (United States)

    Zhou, Min; Li, Yushuang; Zhang, Chen; Li, Shaojie; Wu, Erfu; Li, Wei; Li, Laifeng

    2018-04-01

    Solid-state cooling technologies are considered as possible alternatives for vapor compression cooling systems. The elastocaloric cooling (whose caloric effects are driven by uniaxial stress) technology, as an efficient and clean solid-state cooling technology, is receiving a great deal of attention very recently. Herein, a NiTi-based elastocaloric bulk material was reported. A large coefficient-of-performance of the material (COPmater) of 4.5 was obtained, which was even higher than that of other NiTi bulk materials. The temperature changes (ΔT) increased with increasing applied strain (ɛ), and reached 18 K upon loading and  -11 K upon unloading when the ɛ value increased to 4%. The high temperature changes were attributed to the large stress-induced entropy changes (the maximum ΔS σ value was 37 J kg-1 K-1). The temperature changes decreased with loading-unloading tensile cycles, and stabilized at 6.5 K upon loading and  -6 K upon unloading after tens of mechanical cycles. The Ni50.8Ti49.2 shape memory alloy showed great promise for application in solid-state refrigeration (or as heat pumps).

  2. Effect of ablation geometry on the dynamics, composition, and geometrical shape of thin film plasma

    Science.gov (United States)

    Mondal, Alamgir; Singh, R. K.; Kumar, Ajai

    2018-01-01

    The characteristics of plasma plume produced by front and back ablation of thin films have been investigated using fast imaging and optical emission spectroscopy. Ablation geometry dependence of the plume dynamics, its geometrical aspect and composition is emphasized. Also, the effect of an ambient environment and the beam diameter of an ablating laser on the front and back ablations is briefly discussed. Analysis of time resolved images and plasma parameters indicates that the energetic and spherical plasma formed by front ablation is strikingly different in comparison to the slow and nearly cylindrical plasma plume observed in the case of back ablation. Further shock formation, plume confinement, thermalization and validity of different expansion models in these two ablation geometries are also presented. The present study demonstrates the manipulation of kinetic energy, shape, ion/neutral compositions and directionality of the expanding plume by adjusting the experimental configuration, which is highly relevant to its utilization in various applications e.g., generation of energetic particles, tokamak edge plasma diagnostics, thin film deposition, etc.

  3. Loading Path and Control Mode Effects During Thermomechanical Cycling of Polycrystalline Shape Memory NiTi

    Science.gov (United States)

    Nicholson, D. E.; Benafan, O.; Padula, S. A.; Clausen, B.; Vaidyanathan, R.

    2018-01-01

    Loading path dependencies and control mode effects in polycrystalline shape memory NiTi were investigated using in situ neutron and synchrotron X-ray diffraction performed during mechanical cycling and thermal cycling at constant strain. Strain-controlled, isothermal, reverse loading (to ± 4%) and stress-controlled, isothermal, cyclic loading (to ± 400 MPa for up to ten cycles) at room temperature demonstrated that the preferred martensite variants selected correlated directly with the macroscopic uniaxial strain and did not correlate with the compressive or tensile state of stress. During cyclic loading (up to ten cycles), no significant cycle-to-cycle evolution of the variant microstructure corresponding to a given strain was observed, despite changes in the slope of the stress-strain response with each cycle. Additionally, thermal cycling (to above and below the phase transformation) under constant strain (up to 2% tensile strain) showed that the martensite variant microstructure correlated directly with strain and did not evolve following thermal cycling, despite relaxation of stress in both martensite and austenite phases. Results are presented in the context of variant reorientation and detwinning processes in martensitic NiTi, the fundamental thermoelastic nature of such processes and the ability of the variant microstructure to accommodate irreversible deformation processes.

  4. Effect of shape and resistivity of electrodes in a Faraday MHD duct

    International Nuclear Information System (INIS)

    Jayakumar, R.; Ghosh, S.

    1976-01-01

    The object of achieving uniform current distribution in the presence of high axial fields has prompted the use of resistive electrodes in flat and wedge geometries. In the case of flat geometry the technique involves the generation of voltage drop along the surface of the electrodes in the axial direction, due to the Faraday current collected by the electrode and flowing into a lead wire, to reduce or eliminate the discontinuity in the axial electrical field that would otherwise occur, say in case of metal electrodes. In the case of wedge shapes, higher resistance path is provided for the regions where current is likely to concentrate. In the case of flat geometry, the effect of the position of lead wire also influences the current distribution in the plasma and on the electrode surface. The resistive electrodes have been investigated for the actual current distribution by numerically solving the Laplace's equation for current stream function, arising out of Maxwell's equation and generalised Ohm's law. In the case of wedge electrode, the solution has been sought by numerical analysis of both plasma and electrode zones. It is shown that both geometries, the flat geometry with a lead wire shifted optimally from one edge and the wedge electrode can almost eliminate current concentration. (author)

  5. Effects of Delta-Shaped Obstacles on the Thermal Performance of Solar Air Heater

    Directory of Open Access Journals (Sweden)

    Adisu Bekele

    2011-01-01

    Full Text Available An experimental investigation has been carried out to study the effect of delta-shaped obstacles mounted on the absorber surface of an air heater duct with an aspect ratio 6 : 1 resembling the conditions close to solar air heaters. This study encompassed the Reynolds number (Re ranging from 3400 to 27600, longitudinal pitch of the obstacle (Pl/e varied from 3/2 to 11/2, and relative obstacle height (e/H varied from 0.25 to 0.75. The relative obstacle transverse pitch (Pt/b=7/3 and the angle of attack of flow on obstacle = 90° are kept constant during the whole experimentation. By comparing the heat transfer data obtained from the obstacle-mounted duct with that of smooth duct under similar geometrical and flow conditions, the obstacle-mounted duct enhances the heat transfer by 3.6-times at Re = 7276.82, Pl/e=3/2, and e/H=0.75.

  6. Subjective Significance Shapes Arousal Effects on Modified Stroop Task Performance: A Duality of Activation Mechanisms Account.

    Science.gov (United States)

    Imbir, Kamil K

    2016-01-01

    Activation mechanisms such as arousal are known to be responsible for slowdown observed in the Emotional Stroop and modified Stroop tasks. Using the duality of mind perspective, we may conclude that both ways of processing information (automatic or controlled) should have their own mechanisms of activation, namely, arousal for an experiential mind, and subjective significance for a rational mind. To investigate the consequences of both, factorial manipulation was prepared. Other factors that influence Stroop task processing such as valence, concreteness, frequency, and word length were controlled. Subjective significance was expected to influence arousal effects. In the first study, the task was to name the color of font for activation charged words. In the second study, activation charged words were, at the same time, combined with an incongruent condition of the classical Stroop task around a fixation point. The task was to indicate the font color for color-meaning words. In both studies, subjective significance was found to shape the arousal impact on performance in terms of the slowdown reduction for words charged with subjective significance.

  7. Subjective Significance Shapes Arousal Effects on Modified Stroop Task Performance: a Duality of Activation Mechanisms Account

    Directory of Open Access Journals (Sweden)

    Kamil Konrad Imbir

    2016-02-01

    Full Text Available Activation mechanisms such as arousal are known to be responsible for slowdown observed in the Emotional Stroop (EST and modified Stroop tasks. Using the duality of mind perspective, we may conclude that both ways of processing information (automatic or controlled should have their own mechanisms of activation, namely, arousal for an experiential mind, and subjective significance for a rational mind. To investigate the consequences of both, factorial manipulation was prepared. Other factors that influence Stroop task processing such as valence, concreteness, frequency and word length were controlled. Subjective significance was expected to influence arousal effects. In the first study, the task was to name the color of font for activation charged words. In the second study, activation charged words were, at the same time, combined with an incongruent condition of the classical Stroop task around a fixation point. The task was to indicate the font color for color-meaning words. In both studies, subjective significance was found to shape the arousal impact on performance in terms of the slowdown reduction for words charged with subjective significance.

  8. Molecular Orientation in Two Component Vapor-Deposited Glasses: Effect of Substrate Temperature and Molecular Shape

    Science.gov (United States)

    Powell, Charles; Jiang, Jing; Walters, Diane; Ediger, Mark

    Vapor-deposited glasses are widely investigated for use in organic electronics including the emitting layers of OLED devices. These materials, while macroscopically homogenous, have anisotropic packing and molecular orientation. By controlling this orientation, outcoupling efficiency can be increased by aligning the transition dipole moment of the light-emitting molecules parallel to the substrate. Light-emitting molecules are typically dispersed in a host matrix, as such, it is imperative to understand molecular orientation in two-component systems. In this study we examine two-component vapor-deposited films and the orientations of the constituent molecules using spectroscopic ellipsometry, UV-vis and IR spectroscopy. The role of temperature, composition and molecular shape as it effects molecular orientation is examined for mixtures of DSA-Ph in Alq3 and in TPD. Deposition temperature relative to the glass transition temperature of the two-component mixture is the primary controlling factor for molecular orientation. In mixtures of DSA-Ph in Alq3, the linear DSA-Ph has a horizontal orientation at low temperatures and slight vertical orientation maximized at 0.96Tg,mixture, analogous to one-component films.

  9. Effect of non-ideal clamping shape on the resonance frequencies of silicon nanocantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Guillon, Samuel; Saya, Daisuke; Mazenq, Laurent; Nicu, Liviu [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31077 Toulouse Cedex 4 (France); Perisanu, Sorin; Vincent, Pascal [LPMCN, Universite Claude Bernard Lyon 1 et CNRS, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex (France); Lazarus, Arnaud; Thomas, Olivier, E-mail: sguillon@laas.fr [Structural Mechanics and Coupled Systems Laboratory, Conservatoire National des Arts et Metiers, 2 rue Conte, 75003 Paris (France)

    2011-06-17

    In this paper, we investigate the effects of non-ideal clamping shapes on the dynamic behavior of silicon nanocantilevers. We fabricated silicon nanocantilevers using silicon on insulator (SOI) wafers by employing stepper ultraviolet (UV) lithography, which permits a resolution of under 100 nm. The nanocantilevers were driven by electrostatic force inside a scanning electron microscope (SEM). Both lateral and out-of-plane resonance frequencies were visually detected with the SEM. Next, we discuss overhanging of the cantilever support and curvature at the clamping point in the silicon nanocantilevers, which generally arises in the fabrication process. We found that the fundamental out-of-plane frequency of a realistically clamped cantilever is always lower than that for a perfectly clamped cantilever, and depends on the cantilever width and the geometry of the clamping point structure. Using simulation with the finite-elements method, we demonstrate that this discrepancy is attributed to the particular geometry of the clamping point (non-zero joining curvatures and a flexible overhanging) that is obtained in the fabrication process. The influence of the material orthotropy is also investigated and is shown to be negligible.

  10. Hearing Mouth Shapes: Sound Symbolism and the Reverse McGurk Effect

    Directory of Open Access Journals (Sweden)

    Charles Spence

    2012-09-01

    Full Text Available In their recent article, Sweeny, Guzman-Martinez, Ortega, Grabowecky, and Suzuki (2012 demonstrate that heard speech sounds modulate the perceived shape of briefly presented visual stimuli. Ovals, whose aspect ratio (relating width to height varied on a trial-by-trial basis, were rated as looking wider when a /woo/ sound was presented, and as taller when a /wee/ sound was presented instead. On the one hand, these findings add to a growing body of evidence demonstrating that audiovisual correspondences can have perceptual (as well as decisional effects. On the other hand, they prompt a question concerning their origin. Although the currently popular view is that crossmodal correspondences are based on the internalization of the natural multisensory statistics of the environment (see Spence, 2011, these new results suggest instead that certain correspondences may actually be based on the sensorimotor responses associated with human vocalizations. As such, the findings of Sweeny et al. help to breathe new life into Sapir's (1929 once-popular “embodied” explanation of sound symbolism. Furthermore, they pose a challenge for those psychologists wanting to determine which among a number of plausible accounts best explains the available data on crossmodal correspondences.

  11. CHARACTERIZATIONS ON BENDING EFFECT ON CUSTOMIZED SPLITTERS USING VARIOUS RADII OF ELLIPTICAL-SHAPED BLOCKS

    Directory of Open Access Journals (Sweden)

    L. S. SUPIAN

    2016-11-01

    Full Text Available Macro-bending effect unto polymer optical fiber (POF based splitters study is done to analyse the performance and characterizations using several bending radii of geometrical blocks that hold a customized prepared polymer fiber splitter. A pair of etched fibers with similar core diameters are attached to the ellipse-shaped blocks built using matching refractive index material where the blocks were built with various bending radii. The tapered fibers were lapped closely with some forces exerted upon them in order to stimulate the splitting of modes between the two fibers. This study is done by experimental set-up where each of the splitter ports is connected with optical power meter to measure the power output while pressure is exerted. Characterization is executed in order to investigate and analyse which bending radius gives the most optimize splitting ratio with considerable low loss for the particular splitter prepared. As for normal force of 0.3 lbF, the optimum splitting ratio with low loss is specified having bending radius, Rc, of 13 mm whilst for external force of 3.0 lbF, bending radius is found to be 19 mm. Small bending radius stimulates the radiation of rays into the second fiber while larger Rc gives longer coupling length that optimize the splitting ratios. Efficiencies between simulated values and experimental values are also analysed.

  12. Effect of Piers Shape on the Dynamic Structural Responses of Prestressed Concrete Bridge: Part II

    Directory of Open Access Journals (Sweden)

    Ali Fadhil Naser

    2016-03-01

    Full Text Available Pier of bridge is usually used as a general term for any type of substructure located between horizontal spans and foundations. Piers give vertical supports for spans at intermediate points and perform two main functions. The objective of this study is to inspect the effect of piers shape on the dynamic structural performance by adopting theoretical dynamic analysis. The results of dynamic analysis of 25 bridges models show that the maximum value of natural frequency is equal to 5.64Hz in two circles piers bridge model. Therefore, this type of model has good stiffness and bearing capacity. The two square piers model, the one circle pier model, and the two circles piers model appear good stiffness because of the natural frequencies (5.30Hz, 5.52Hz, and 5.64Hz are more than the maximum forced frequencies (4.52Hz, 5.45Hz, and 4.52Hz respectively. According to the comparison between all models results, the two circles piers model has the higher stiffness because of this model has the maximum value of natural frequency (5.64Hz and it is more than all forced vibration frequencies of all others models. Therefore, this study recommends that using the bridge model of two circles piers in the bridges construction that consists of three spans (30m+40m+30m with section of box girder.

  13. Effect of Piers Shape on the Dynamic Structural Responses of Prestressed Concrete Bridge: Part II

    Directory of Open Access Journals (Sweden)

    Ali Fadhil Naser

    2016-12-01

    Full Text Available Pier of bridge is usually used as a general term for any type of substructure located between horizontal spans and foundations. Piers give vertical supports for spans at intermediate points and perform two main functions. The objective of this study is to inspect the effect of piers shape on the dynamic structural performance by adopting theoretical dynamic analysis. The results of dynamic analysis of 25 bridges models show that the maximum value of natural frequency is equal to 5.64Hz in two circles piers bridge model. Therefore, this type of model has good stiffness and bearing capacity. The two square piers model, the one circle pier model, and the two circles piers model appear good stiffness because of the natural frequencies (5.30Hz, 5.52Hz, and 5.64Hz are more than the maximum forced frequencies (4.52Hz, 5.45Hz, and 4.52Hz respectively. According to the comparison between all models results, the two circles piers model has the higher stiffness because of this model has the maximum value of natural frequency (5.64Hz and it is more than all forced vibration frequencies of all others models. Therefore, this study recommends that using the bridge model of two circles piers in the bridges construction that consists of three spans (30m+40m+30m with section of box girder.

  14. The geometric effect and programming current reduction in cylindrical-shaped phase change memory

    International Nuclear Information System (INIS)

    Li Yiming; Hwang, C-H; Li, T-Y; Cheng, H-W

    2009-01-01

    This study conducts a three-dimensional electro-thermal time-domain simulation for numerical analysis of cylindrical-shaped phase change memories (PCMs). The influence of chalcogenide material, germanium antimony telluride (GeSbTe or GST), structure on PCM operation is explored. GST with vertical structure exhibits promising characteristics. The bottom electrode contact (BEC) is advanced to improve the operation of PCMs, where a 25% reduction of the required programming current is achieved at a cost of 26% reduced resistance ratio. The position of the BEC is then shifted to further improve the performance of PCMs. The required programming current is reduced by a factor of 11, where the resistance ratio is only decreased by 6.9%. However, the PCMs with a larger shift of BEC are sensitive to process variation. To design PCMs with less than 10% programming current variation, PCMs with shifted BEC, where the shifted distance is equal to 1.5 times the BEC's radius, is worth considering. This study quantitatively estimates the structure effect on the phase transition of PCMs and physically provides an insight into the design and technology of PCMs.

  15. The effects of scoliosis and subsequent surgery on the shape of the torso

    Directory of Open Access Journals (Sweden)

    Adrian Gardner

    2017-11-01

    Full Text Available Abstract Background Adolescent idiopathic scoliosis (AIS causes asymmetry of the torso, and this is often the primary concern of patients. Surgery aims to minimise the visual asymmetry. It is not clear how scoliosis makes the torso asymmetric or how scoliosis surgery changes that asymmetry when compared to the distribution of asymmetries seen in a non-scoliotic group of normal controls. Methods Surface topography images were captured for a group with AIS both pre-operatively and post-operatively. Identifiable points were compared between the images to identify the effects of AIS on the shape of the torso by looking at the relative heights and distances from the midline of the shoulders, axillae and waist in a two-dimensional coronal view. This was then compared to a previously reported group of normal non-scoliotic children to analyse whether surgery recreated normality. Results There were 172 pairs of images with 164 females and 8 males, mean age at pre-operative scan of 13.7 years. The normal group was 642 images (237 females and 405 males from 116 males and 79 females, mean age of 12.5 years. The curve patterns seen in the scoliotic group matched the patterns of a main thoracic curve (n = 146 and main thoracolumbar curve (n = 26. The asymmetries seen in both shoulders, axillae and waist were different between the two different types of curve. Across both groups, the shoulder asymmetry was less than that of the corresponding axillae. There was a statistically significant reduction in all asymmetries following surgery in the main thoracic group (p < 0.001. This was not seen in the main thoracolumbar group, thought to be due to the small sample size. In the main thoracic group, there were statistically significant differences in the asymmetries between the post-operative and normal groups in the shoulders and axillae (p < 0.001 but not the waist. Conclusions This paper demonstrates quantitatively the range of asymmetries seen

  16. The effects of workforce-shaping tools on retirement: the case of the Department of Defense civil service.

    Science.gov (United States)

    Asch, Beth J; Haider, Steven J; Zissimopoulos, Julie M

    2009-11-01

    Apriority area for the public health workforce research agenda is the study of the public health labor market and how wages and benefits affect workforce outcomes, including recruiting, retention, and retirement. This study provides an example of such a study for the Department of Defense civil service workforce. We analyze the financial incentives to retire that are specifically embedded in the retirement system and how different workforce-shaping policies would affect these incentives. The study then uses a recently estimated model of the effects of financial incentives on retirement behavior among defense civilians to predict how these workforce-shaping tools would affect retirement behavior. We find that buyouts, retention incentives, and other workforce-shaping tools have a sizable effect on predicted retirement behavior and therefore, could be useful policies to help manage retirement outflows.

  17. Effects of shape and size of inclusions on the sintering of ZnO-ZrO2 composites

    International Nuclear Information System (INIS)

    Nakada, Yohsuke; Kimura, Toshio

    1997-01-01

    The densification behavior and microstructure development of ZnO matrices containing rigid ZrO 2 inclusions were studied, with special emphasis on the effect of inclusion shape and size. The inclusions retarded the densification of the matrix, regardless of the inclusion shape and size. For large inclusions with diameter of > 10 microm, dense regions developed between inclusion particles. The inclusion particles and dense regions formed a continuous network, which constrained the densification of the composites. The inclusion shape had a small effect on the development of dense regions. Severe retardation in densification was observed for compacts containing inclusions with diameters of < 10 microm. In these cases, dense regions between inclusion particles did not develop. The formation of the continuous network cannot be applicable to small inclusions as an origin of retardation of densification

  18. Shape-Selection of Thermodynamically Stabilized Colloidal Pd and Pt Nanoparticles Controlled via Support Effects

    DEFF Research Database (Denmark)

    Ahmadi, M.; Behafarid, F.; Holse, Christian

    2015-01-01

    Colloidal chemistry, in combination with nanoparticle (NP)/support epitaxial interactions is used here to synthesize shape-selected and thermodynamically stable metallic NPs over a broad range of NP sizes. The morphology of three-dimensional palladium and platinum NPs supported on TiO2(110) was i......Colloidal chemistry, in combination with nanoparticle (NP)/support epitaxial interactions is used here to synthesize shape-selected and thermodynamically stable metallic NPs over a broad range of NP sizes. The morphology of three-dimensional palladium and platinum NPs supported on TiO2...... rows and was found to be responsible for the shape control. The ability of synthesizing thermally stable shape-selected metal NPs demonstrated here is expected to be of relevance for applications in the field of catalysis, since the activity and selectivity of NP catalysts has been shown to strongly...

  19. Unusual shapes for a catenary under the effects of surface tension and gravity: A variational treatment

    International Nuclear Information System (INIS)

    Behroozi, F.; Mohazzabi, P.; McCrickard, J.

    1995-01-01

    The familiar catenary is the shape assumed by a chain or string as it hangs from two points. The mathematical equation of the catenary was first published more than three hundred years ago by Leibnitz and Huygen, among others. Here we consider the shapes assumed by a hanging string in the presence of gravity and surface tension. The surface tension is introduced by suspending the string from a thin horizontal rod while the area bounded by the string and the rod is covered with a soap film. The string then assumes new and wonderful shapes depending on the relative strength of the surface tension and the weight per unit length of the string. When surface tension dominates, the string is pulled inward, assuming a convex shape similar to the Greek letter γ. On the other hand, when gravity is dominant the string is pulled outward and assumes a concave shape best described as a distorted catenary. However, when the gravitational force normal to the string matches the surface tension, the string takes a linear configuration similar to the letter V. Under suitable conditions, the string can be made to assume any of the three configurations by adjusting the separation of its end points. The equations that describe the shape of the string are derived by minimizing the total energy of the system and are presented for the three principal configurations

  20. Effects of surface characteristics on the plantar shape of feet and subjects' perceived sensations.

    Science.gov (United States)

    Witana, Channa P; Goonetilleke, Ravindra S; Xiong, Shuping; Au, Emily Y L

    2009-03-01

    Orthotics and other types of shoe inserts are primarily designed to reduce injury and improve comfort. The interaction between the plantar surface of the foot and the load-bearing surface contributes to foot and surface deformations and hence to perceived comfort, discomfort or pain. The plantar shapes of 16 participants' feet were captured when standing on three support surfaces that had different cushioning properties in the mid-foot region. Foot shape deformations were quantified using 3D laser scans. A questionnaire was used to evaluate the participant's perceptions of perceived shape and perceived feeling. The results showed that the structure in the mid-foot could change shape, independent of the rear-foot and forefoot regions. Participants were capable of identifying the shape changes with distinct preferences towards certain shapes. The cushioning properties of the mid-foot materials also have a direct influence on perceived feelings. This research has strong implications for the design and material selection of orthotics, insoles and footwear.

  1. The effect of shape on the fracture of a soft elastic gel subjected to shear load.

    Science.gov (United States)

    Kundan, Krishna Kant; Ghatak, Animangsu

    2018-02-21

    For brittle solids, the fracture energy is the energy required to create a unit area of new surface through the process of division. For crosslinked materials, it is a function of the intrinsic properties like crosslinking density and bond strength of the crosslinks. Here we show that the energy released due to fracture can depend also on the shape of a joint made of this material. Our experiment involves two gel blocks connected via a thin gel disk. The disk is formed into different regular and exotic shapes, but with identical areas of cross-section. When one of the blocks is sheared with respect to the other, the shear load increases with vertical displacement, eventually causing a fracture at a threshold load. The maximum fracture load is different for different disks and among different regularly shaped disks, it is at a maximum for pentagon and hexagon shapes. The fracture energy release rate of the joint depends also on the aspect ratio (height/width) of the shapes. Our experiments also throw light on possible reasons for such a dependence on the shape of the joints.

  2. Influence of atomic ordering on elastocaloric and magnetocaloric effects of a Ni–Cu–Mn–Ga ferromagnetic shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chonghui [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Yu, E-mail: yuwang@mail.xjtu.edu.cn [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China); Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an 710049 (China); Tang, Zhao; Liao, Xiaoqi; Yang, Sen; Song, Xiaoping [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China)

    2015-05-05

    Highlights: • Ni{sub 51}Cu{sub 4}Mn{sub 20}Ga{sub 25} alloy exhibits normal elastocaloric and magnetocaloric effects. • L2{sub 1} atomic order of the alloy is increased after annealing at 773 K for 10 h. • Increasing L2{sub 1} atomic order improves its elastocaloric and magnetocaloric effects. • Atomic ordering modifies the magnetic and martensitic transitions of the system. - Abstract: The coexisting elastocaloric and magnetocaloric effects in ferromagnetic shape memory alloys have attracted much attention for the potential application in solid state refrigeration. Previous studies show that the L2{sub 1} atomic ordering of Heusler ferromagnetic shape memory alloys plays important role on their magnetocaloric effect. However, no research work investigates the effect of atomic ordering on their elastocaloric effect yet. In this study, we investigated the influence of atomic ordering on the elastocaloric and magnetocaloric effects of a Ni{sub 51}Cu{sub 4}Mn{sub 20}Ga{sub 25} ferromagnetic shape memory alloy. The alloy exhibits normal elastocaloric effect and normal magnetocaloric effect near room temperature. Moreover, we found that the enhancement of atomic order in this alloy can greatly increase the entropy change and refrigeration capacity of its elastocaloric and magnetocaloric effects. This is attributed to that the atomic ordering modifies the magnetic and martensitic transitions of the system.

  3. Influence of atomic ordering on elastocaloric and magnetocaloric effects of a Ni–Cu–Mn–Ga ferromagnetic shape memory alloy

    International Nuclear Information System (INIS)

    Huang, Chonghui; Wang, Yu; Tang, Zhao; Liao, Xiaoqi; Yang, Sen; Song, Xiaoping

    2015-01-01

    Highlights: • Ni 51 Cu 4 Mn 20 Ga 25 alloy exhibits normal elastocaloric and magnetocaloric effects. • L2 1 atomic order of the alloy is increased after annealing at 773 K for 10 h. • Increasing L2 1 atomic order improves its elastocaloric and magnetocaloric effects. • Atomic ordering modifies the magnetic and martensitic transitions of the system. - Abstract: The coexisting elastocaloric and magnetocaloric effects in ferromagnetic shape memory alloys have attracted much attention for the potential application in solid state refrigeration. Previous studies show that the L2 1 atomic ordering of Heusler ferromagnetic shape memory alloys plays important role on their magnetocaloric effect. However, no research work investigates the effect of atomic ordering on their elastocaloric effect yet. In this study, we investigated the influence of atomic ordering on the elastocaloric and magnetocaloric effects of a Ni 51 Cu 4 Mn 20 Ga 25 ferromagnetic shape memory alloy. The alloy exhibits normal elastocaloric effect and normal magnetocaloric effect near room temperature. Moreover, we found that the enhancement of atomic order in this alloy can greatly increase the entropy change and refrigeration capacity of its elastocaloric and magnetocaloric effects. This is attributed to that the atomic ordering modifies the magnetic and martensitic transitions of the system

  4. Effect of thermal conductivities of shape stabilized PCM on under-floor heating system

    International Nuclear Information System (INIS)

    Cheng, Wenlong; Xie, Biao; Zhang, Rongming; Xu, Zhiming; Xia, Yuting

    2015-01-01

    Highlights: • HCE-SSPCM was prepared and used in under-floor heating system. • Enhancing thermal conductivity improved the efficiency of energy and space. • Too high thermal conductivity over a range was meaningless. • The economic benefits of the phase change energy storage system were the best. - Abstract: A kind of heat conduction-enhanced shape-stabilized PCM (HCE-SSPCM) was utilized in the under-floor heating system for house heating in winter. This system charges heat by using cheap nighttime electricity and provides heating needs throughout all day. The effect of thermal conductivity of the PCM on energy savings and economic benefits of the system were theoretically and experimentally studied. HCE-SSPCM plates, made of (solid paraffin + liquid paraffin)/high density polyethylene/expanded graphite, were introduced to a test room with under-floor heating system. And the operating characteristics of the system were compared with that of the non-phase change energy storage system and the conventional air conditioning system. The results showed that enhancing the thermal conductivity of PCM in a certain range could significantly improve the energy efficiency of the heating system and reduce the thickness of thermal insulating materials. But the improving effect was not obvious when the thermal conductivity was beyond 1.0 W/m K. The phase change energy storage system had a comfortable temperature environment and the best economic benefits among the three different heating types especially when the ratio of peak-valley electric price was high. Therefore, increasing the thermal conductivity of SSPCM will be of great significance for house heating

  5. Effects of shielding coatings on the anode shaping process during counter-rotating electrochemical machining

    Science.gov (United States)

    Wang, Dengyong; Zhu, Zengwei; Wang, Ningfeng; Zhu, Di

    2016-09-01

    Electrochemical machining (ECM) has been widely used in the aerospace, automotive, defense and medical industries for its many advantages over traditional machining methods. However, the machining accuracy in ECM is to a great extent limited by the stray corrosion of the unwanted material removal. Many attempts have been made to improve the ECM accuracy, such as the use of a pulse power, passivating electrolytes and auxiliary electrodes. However, they are sometimes insufficient for the reduction of the stray removal and have their limitations in many cases. To solve the stray corrosion problem in CRECM, insulating and conductive coatings are respectively used. The different implement processes of the two kinds of coatings are introduced. The effects of the two kinds of shielding coatings on the anode shaping process are investigated. Numerical simulations and experiments are conducted for the comparison of the two coatings. The simulation and experimental results show that both the two kinds of coatings are valid for the reduction of stray corrosion on the top surface of the convex structure. However, for insulating coating, the convex sidewall becomes concave when the height of the convex structure is over 1.26 mm. In addition, it is easy to peel off by the high-speed electrolyte. In contrast, the conductive coating has a strong adhesion, and can be well reserved during the whole machining process. The convex structure fabricated by using a conductive iron coating layer presents a favorable sidewall profile. It is concluded that the conductive coating is more effective for the improvement of the machining quality in CRECM. The proposed shielding coatings can also be employed to reduce the stray corrosion in other schemes of ECM.

  6. Room temperature magnetocaloric effect in Ni-Mn-In-Cr ferromagnetic shape memory alloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akkera, Harish Sharma [Functionalnanomaterials Research Lab, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand-247667 (India); Singh, Inderdeep [Mechanical and Industrial Engineering Department, Indian Institute of Technology Roorkee, Uttarakhand-24667 (India); Kaur, Davinder, E-mail: dkaurfph@iitr.ernet.in [Functionalnanomaterials Research Lab, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand-247667 (India)

    2017-02-15

    The influence of Cr substitution for In on the martensitic phase transformation and magnetocaloric effect (MCE) has been investigated in Ni-Mn-Cr-In ferromagnetic shape memory alloy (FSMA) thin films fabricated by magnetron sputtering. Temperature dependent magnetization (M-T) measurements demonstrated that the martensitic transformation temperatures (T{sub M}) monotonously increase with the increase of Cr content due to change in valence electron concentration (e/a) and cell volume. From the study of isothermal magnetization curves (M-H), magnetocaloric effect around the martensitic transformation has been investigated in these FSMA thin films. The magnetic entropy change ∆S{sub M} of 7.0 mJ/cm{sup 3}-K was observed in Ni{sub 51.1}Mn{sub 34.9}In{sub 9.5}Cr{sub 4.5} film at 302 K in an applied field of 2 T. Further, the refrigerant capacity (RC) was also calculated for all the films in an applied field of 2 T. These findings indicate that the Cr doped Ni-Mn-In FSMA thin films are potential candidates for room temperature micro-length-scale magnetic refrigeration applications. - Highlights: • The Cr content leads to an increase in the martensitic transformation temperature. • The ∆S{sub M} =7 mJ/cm{sup 3}-K at 302 K was observed in the Ni{sub 51.1}Mn{sub 34.9}In{sub 9.5}Cr{sub 4.5}. • The RC =39.2 mJ/K at 2 T was obtained in Ni{sub 51.1}Mn{sub 34.9}In{sub 9.5}Cr{sub 4.5} film.

  7. Investigation of Corner Effect and Identification of Tunneling Regimes in L-Shaped Tunnel Field-Effect-Transistor.

    Science.gov (United States)

    Najam, Faraz; Yu, Yun Seop

    2018-09-01

    Corner-effect existing in L-shaped tunnel field-effect-transistor (LTFET) was investigated using numerical simulations and band diagram analysis. It was found that the corner-effect is caused by the convergence of electric field in the sharp source corner present in an LTFET, thereby increasing the electric field in the sharp source corner region. It was found that in the corner-effect region tunneling starts early, as a function of applied bias, as compared to the rest of the channel not affected by corner-effect. Further, different tunneling regimes as a function of applied bias were identified in the LTFET including source to channel and channel to channel tunneling regimes. Presence of different tunneling regimes in LTFET was analytically justified with a set of equations developed to model source to channel, and channel to channel tunneling currents. Drain-current-gate-voltage (Ids-Vgs) characteristics obtained from the equations is in reasonable qualitative agreement with numerical simulation.

  8. The effects of focusing power on TEA CO2 laser-induced gas breakdown and the consequent pulse shaping effects

    Science.gov (United States)

    Beheshtipour, Saleheh; Safari, Ebrahim; Majdabadi, Abbas; Silakhori, Kaveh

    2018-02-01

    Transversely Excited Atmospheric (TEA) CO2 laser pulses were used in order to generate an optical breakdown in a variety of mono- and polyatomic molecules using different focusing powers. The dependence of the spark kernel geometry and the transmitted pulse shapes on the focusing power as well as the pressure, molecular weight, and ionization energy of the gases was investigated in detail. Partial removal of the transmitted pulse tail in the 0.05-2.6 μs range together with shortened spikes in the 10-60 ns range has been observed by applying a 2.5 cm focal length lens for all the gases. At higher focal lengths, this effect is only incompletely observed for He gas. Spatial-temporal analyses of the laser beams and the relevant plasma plumes indicate that this behavior is due to the drop in the plasma density below the critical level, before the laser pulse tail is completed.

  9. NEUTRON-PROTON EFFECTIVE RANGE PARAMETERS AND ZERO-ENERGY SHAPE DEPENDENCE.

    Energy Technology Data Exchange (ETDEWEB)

    HACKENBURG, R.W.

    2005-06-01

    A completely model-independent effective range theory fit to available, unpolarized, np scattering data below 3 MeV determines the zero-energy free proton cross section {sigma}{sub 0} = 20.4287 {+-} 0.0078 b, the singlet apparent effective range r{sub s} = 2.754 {+-} 0.018{sub stat} {+-} 0.056{sub syst} fm, and improves the error slightly on the parahydrogen coherent scattering length, a{sub c} = -3.7406 {+-} 0.0010 fm. The triplet and singlet scattering lengths and the triplet mixed effective range are calculated to be a{sub t} = 5.4114 {+-} 0.0015 fm, a{sub s} = -23.7153 {+-} 0.0043 fm, and {rho}{sub t}(0,-{epsilon}{sub t}) = 1.7468 {+-} 0.0019 fm. The model-independent analysis also determines the zero-energy effective ranges by treating them as separate fit parameters without the constraint from the deuteron binding energy {epsilon}{sub t}. These are determined to be {rho}{sub t}(0,0) = 1.705 {+-} 0.023 fm and {rho}{sub s}(0,0) = 2.665 {+-} 0.056 fm. This determination of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is most sensitive to the sparse data between about 20 and 600 keV, where the correlation between the determined values of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is at a minimum. This correlation is responsible for the large systematic error in r{sub s}. More precise data in this range are needed. The present data do not event determine (with confidence) that {rho}{sub t}(0,0) {ne} {rho}{sub t}(0, -{epsilon}{sub t}), referred to here as ''zero-energy shape dependence''. The widely used measurement of {sigma}{sub 0} = 20.491 {+-} 0.014 b from W. Dilg, Phys. Rev. C 11, 103 (1975), is argued to be in error.

  10. Moessbauer study of the ageing effects on the structure of CuZnSn shape memory alloy

    International Nuclear Information System (INIS)

    Frackowiak, J.E.; Dutkiewicz, J.; Morgiel, J.

    1986-01-01

    Using the 119 Sn Moessbauer spectroscopy the study of ageing effects on the structure of a CuZnSn shape memory alloy was performed. Two stages of ageing at 200 0 C were observed. The first stage is connected with formation of DO 3 structure and the second stage with precipitation of α and γ phases. (Auth.)

  11. Exploiting object constancy: effects of active exploration and shape morphing on similarity judgments of novel objects.

    Science.gov (United States)

    Lee, Haemy; Wallraven, Christian

    2013-03-01

    Humans are experts at shape processing. This expertise has been learned and fine tuned by actively manipulating and perceiving thousands of objects during development. Therefore, shape processing possesses an active component and a perceptual component. Here, we investigate both components in six experiments in which participants view and/or interact with novel, parametrically defined 3D objects using a touch-screen interface. For probing shape processing, we use a similarity rating task. In Experiments 1-3, we show that active manipulation leads to a better perceptual reconstruction of the physical parameter space than judging rotating objects, or passively viewing someone else's exploration pattern. In Experiment 4, we exploit object constancy-the fact that the visual system assumes that objects do not change their identity during manipulation. We show that slow morphing of an object during active manipulation systematically biases similarity ratings-despite the participants being unaware of the morphing. Experiments 5 and 6 investigate the time course of integrating shape information by restricting the morphing to the first and second half of the trial only. Interestingly, the results indicate that participants do not seem to integrate shape information beyond 5 s of exploration time. Finally, Experiment 7 uses a secondary task that suggests that the previous results are not simply due to lack of attention during the later parts of the trial. In summary, our results demonstrate the advantage of active manipulation for shape processing and indicate a continued, perceptual integration of complex shape information within a time window of a few seconds during object interactions.

  12. Investigation of high frequency external perturbation effects on flow in a T-shape microchannel by μLIF technique

    Science.gov (United States)

    Kravtsova, A. Yu; Meshalkin, Yu E.; Bilsky, A. V.

    2017-11-01

    Investigation of high frequency external perturbation effect on flow inside T-shape microchannel was examined. In-phase pulsations of different frequencies were added to both inlets of the T-shaped microchannel to study mixing by means of Micro Laser Induced Fluorescence (μLIF) technique. For all flow regimes studied, mixing enhancement was obtained. Significant enhancement can be achieved at the beginning of the outlet channel operating in steady asymmetric regime (Re=186) by forcing at certain frequency ranges (f = 500Hz, f = 800Hz). Mixing suppression was also observed for two flow regimes (Re = 400, f = 1000Hz) and (Re = 120, f = 700Hz).

  13. The effect of shaped wheelchair cushion and lumbar supports on under-seat pressure, comfort, and pelvic rotation.

    Science.gov (United States)

    Samuelsson, Kersti; Björk, Maarit; Erdugan, Ann-Marie; Hansson, Anna-Karin; Rustner, Birgitta

    2009-09-01

    A wheelchair seat and position help clients perform daily activities. The comfort of the wheelchair can encourage clients to participate in daily activities and can help prevent future complications. This study evaluates how a shaped seat-cushion and two different back supports affect under-seat pressure, comfort, and pelvic rotation. Thirty healthy subjects were tested using two differently equipped manual wheelchairs. One wheelchair had a Velcro adjustable back seat and a plane seat-cushion. The other wheelchair had a non-adjustable sling-back seat and a plane cushion. The second wheelchair was also equipped with a shaped cushion and/or a detachable lumbar support. Under-seat pressure, estimated comfort, and pelvic rotation were measured after 10 min in each wheelchair outfit. Peak pressure increased with the shaped cushion compared to the plane cushion. No significant difference in estimated comfort was found. Pelvic posterior-rotation was reduced with the adjustable or detachable back-support irrespective of the shape of the seat cushion. To support a neutral pelvic position and spinal curvature, a combination of a shaped cushion and a marked lumbar support is most effective.

  14. Effect of Si on the reversibility of stress-induced martensite in Fe-Mn-Si shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Stanford, N. [Centre for Material and Fibre Innovation, Deakin University, Geelong, Victoria 3217 (Australia); Dunne, D.P., E-mail: druce_dunne@uow.edu.au [Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2010-12-15

    Fe-Mn-Si is a well-characterized ternary shape memory alloy. Research on this alloy has consistently shown that the addition of 5-6 wt.% Si is desirable to enhance the reversibility of stress-induced martensite vis-a-vis shape memory. This paper examines the effect of Si on the morphology and the crystallography of the martensite in the Fe-Mn-Si system. It is concluded that the addition of Si increases the c/a ratio of the martensite, reduces the transformation volume change and decreases the atomic spacing difference between the parallel close-packed directions in the austenite-martensite interface (habit) plane. It is proposed that, in addition to austenite strengthening, Si enhances reversibility by reducing the volume change and the interfacial atomic mismatch between the martensite and the austenite. Although shape memory is improved, transformation reversibility remains limited by the necessary misfit dislocations that accommodate the atomic spacing differences in the interface.

  15. Small-angle scattering of polychromatic X-rays: effects of bandwidth, spectral shape and high harmonics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Sen; Luo, Sheng-Nian

    2018-02-16

    Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10–100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are exploredviaGaussian and half-Gaussian spectra. Synchrotron undulator spectra represented by two undulator sources of the Advanced Photon Source are examined as an example, as regards the influence of asymmetric harmonic shape, fundamental harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.

  16. Effect of Si on the reversibility of stress-induced martensite in Fe-Mn-Si shape memory alloys

    International Nuclear Information System (INIS)

    Stanford, N.; Dunne, D.P.

    2010-01-01

    Fe-Mn-Si is a well-characterized ternary shape memory alloy. Research on this alloy has consistently shown that the addition of 5-6 wt.% Si is desirable to enhance the reversibility of stress-induced martensite vis-a-vis shape memory. This paper examines the effect of Si on the morphology and the crystallography of the martensite in the Fe-Mn-Si system. It is concluded that the addition of Si increases the c/a ratio of the martensite, reduces the transformation volume change and decreases the atomic spacing difference between the parallel close-packed directions in the austenite-martensite interface (habit) plane. It is proposed that, in addition to austenite strengthening, Si enhances reversibility by reducing the volume change and the interfacial atomic mismatch between the martensite and the austenite. Although shape memory is improved, transformation reversibility remains limited by the necessary misfit dislocations that accommodate the atomic spacing differences in the interface.

  17. Research of Effective Width of FRP U-shaped Hoop Reinforcement Properties of Concrete Beams by Shear

    Directory of Open Access Journals (Sweden)

    Li Baokun

    2015-01-01

    Full Text Available The paste fiber reinforced composite material (hereinafter referred to as FRP U-shaped hoop of reinforced concrete beams interfacial debonding is an important reinforcement technology research. For the effective width of the CFRP U-shaped hoop reinforcement, it is still a lack of in-depth research, only relying on the test research huge workload, this article (ANSYS and the numerical simulation in the whole process of the shear load release properties of finite element calculation software. According to the results of finite element analysis, the author studied the CFRP U-shaped hoop to increase the width of the shear capacity of reinforced concrete beams by the impact.

  18. Small-angle scattering of polychromatic X-rays: effects of bandwidth, spectral shape and high harmonics.

    Science.gov (United States)

    Chen, Sen; Luo, Sheng Nian

    2018-03-01

    Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10-100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are explored via Gaussian and half-Gaussian spectra. Synchrotron undulator spectra represented by two undulator sources of the Advanced Photon Source are examined as an example, as regards the influence of asymmetric harmonic shape, fundamental harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.

  19. Synergistic effect of carbon nanofiber and sub-micro filamentary nickel nanostrand on the shape memory polymer nanocomposite

    International Nuclear Information System (INIS)

    Lu, Haibao; Leng, Jinsong; Du, Shanyi; Gou, Jihua

    2011-01-01

    This work studies the synergistic effect of carbon nanofiber (CNF) and sub-micro filamentary nickel nanostrand on the thermal and electrical properties, as well as the electro-active shape memory behavior, of a shape memory polymer (SMP) nanocomposite. The combination of electrical CNF and electromagnetic nickel nanostrand is used to render insulating thermo-responsive SMPs conductive. Subsequently, the shape memory behavior of the SMP can be activated by the electrical resistive heating. It is shown that sub-micro filamentary nickel-coated nanostrands significantly improved the electrical conductivity to facilitate the actuation of the SMP nanocomposite despite the low nanostrand volume content and low electrical voltage. Also the CNFs are blended with the SMP resin to facilitate the dispersion of nanostrands and improve the thermal conductivity to accelerate the electro- and thermo-active responses

  20. The effect of disease and respiration on airway shape in patients with moderate persistent asthma.

    Directory of Open Access Journals (Sweden)

    Spyridon Montesantos

    Full Text Available Computational models of gas transport and aerosol deposition frequently utilize idealized models of bronchial tree structure, where airways are considered a network of bifurcating cylinders. However, changes in the shape of the lung during respiration affect the geometry of the airways, especially in disease conditions. In this study, the internal airway geometry was examined, concentrating on comparisons between mean lung volume (MLV and total lung capacity (TLC. A set of High Resolution CT images were acquired during breath hold on a group of moderate persistent asthmatics at MLV and TLC after challenge with a broncho-constrictor (methacholine and the airway trees were segmented and measured. The airway hydraulic diameter (Dh was calculated through the use of average lumen area (Ai and average internal perimeter (Pi at both lung volumes and was found to be systematically higher at TLC by 13.5±9% on average, with the lower lobes displaying higher percent change in comparison to the lower lobes. The average internal diameter (Din was evaluated to be 12.4±6.8% (MLV and 10.8±6.3% (TLC lower than the Dh, for all the examined bronchi, a result displaying statistical significance. Finally, the airway distensibility per bronchial segment and per generation was calculated to have an average value of 0.45±0.28, exhibiting high variability both between and within lung regions and generations. Mixed constriction/dilation patterns were recorded between the lung volumes, where a number of airways either failed to dilate or even constricted when observed at TLC. We conclude that the Dh is higher than Din, a fact that may have considerable effects on bronchial resistance or airway loss at proximal regions. Differences in caliber changes between lung regions are indicative of asthma-expression variability in the lung. However, airway distensibility at generation 3 seems to predict distensibility more distally.

  1. Subcellular topological effect of particle monolayers on cell shapes and functions.

    Science.gov (United States)

    Miura, Manabu; Fujimoto, Keiji

    2006-12-01

    We studied topological effects of subcellular roughness displayed by a closely packed particle monolayer on adhesion and growth of endothelial cells. Poly(styrene-co-acrylamide) (SA) particles were prepared by soap-free emulsion copolymerization. Particle monolayers were prepared by Langmuir-Blodgett deposition using particles, which were 527 (SA053) and 1270 nm (SA127) in diameter. After 24-h incubation, cells tightly adhered on a tissue culture polystyrene dish and randomly spread. On the other hand, cells attached on particle monolayers were stretched into a narrow stalk-like shape. Lamellipodia spread from the leading edge of cells attached on SA053 monolayer to the top of the particles and gradually gathered to form clusters. This shows that cell-cell adhesion became stronger than cell-substrate interaction. Cells attached to SA127 monolayer extended to the reverse side of a particle monolayer and engulfed particles. They remained immobile without migration 24h after incubation. This shows that the inhibition of extensions on SA127 monolayer could inhibit cell migration and cell proliferation. Cell growth on the particle monolayers was suppressed compared with a flat TCPS dish. The number of cells on SA053 gradually increased, whereas that on SA127 decreased with time. When the cell seeding density was increased to 200,000 cells cm(-2), some adherent cells gradually became into contact with adjacent cells. F-actin condensations were formed at the frame of adherent cells and the thin filaments grew from the edges to connect each other with time. For the cell culture on SA053 monolayer, elongated cells showed a little alignment. Cells showed not arrangement of actin stress fibers but F-actin condensation at the contact regions with neighboring cells. Interestingly, the formed cell monolayer could be readily peeled from the particle monolayer. These results indicate that endothelial cells could recognize the surface roughness displayed by particle monolayers and

  2. EFFECT OF PROFILES AND SHAPE ON IDEAL STABILITY OF ADVANCED TOKAMAK EQUILIBRIA

    Energy Technology Data Exchange (ETDEWEB)

    MAKOWSKI,MA; CASPER,TA; FERRON,JR; TAYLOR,TS; TURNBULL,AD

    2003-08-01

    OAK-B135 The pressure profile and plasma shape, parameterized by elongation ({kappa}), triangularity ({delta}), and squareness ({zeta}), strongly influence stability. In this study, ideal stability of single null and symmetric, double-null, advanced tokamak (AT) configurations is examined. All the various shapes are bounded by a common envelope and can be realized in the DIII-D tokamak. The calculated AT equilibria are characterized by P{sub 0}/

    {approx} 2.0-4.5, weak negative central shear, high q{sub min} (> 2.0), high bootstrap fraction, an H-mode pedestal, and varying shape parameters. The pressure profile is modeled by various polynomials together with a hyperbolic tangent pedestal, consistent with experimental observations. Stability is calculated with the DCON code and the resulting stability boundary is corroborated by GATO runs.

  3. Effect of panel shape of soccer ball on its flight characteristics

    Science.gov (United States)

    Hong, Sungchan; Asai, Takeshi

    2014-05-01

    Soccer balls are typically constructed from 32 pentagonal and hexagonal panels. Recently, however, newer balls named Cafusa, Teamgeist 2, and Jabulani were respectively produced from 32, 14, and 8 panels with shapes and designs dramatically different from those of conventional balls. The newest type of ball, named Brazuca, was produced from six panels and will be used in the 2014 FIFA World Cup in Brazil. There have, however, been few studies on the aerodynamic properties of balls constructed from different numbers and shapes of panels. Hence, we used wind tunnel tests and a kick-robot to examine the relationship between the panel shape and orientation of modern soccer balls and their aerodynamic and flight characteristics. We observed a correlation between the wind tunnel test results and the actual ball trajectories, and also clarified how the panel characteristics affected the flight of the ball, which enabled prediction of the trajectory.

  4. EFFECT OF PROFILES AND SHAPE ON IDEAL STABILITY OF ADVANCED TOKAMAK EQUILIBRIA

    International Nuclear Information System (INIS)

    MAKOWSKI, M.A.; CASPER, T.A.; FERRON, J.R.; TAYLOR, T.S.; TURNBULL, A.D.

    2003-01-01

    OAK-B135 The pressure profile and plasma shape, parameterized by elongation (κ), triangularity ((delta)), and squareness (ζ), strongly influence stability. In this study, ideal stability of single null and symmetric, double-null, advanced tokamak (AT) configurations is examined. All the various shapes are bounded by a common envelope and can be realized in the DIII-D tokamak. The calculated AT equilibria are characterized by P 0 / ∼ 2.0-4.5, weak negative central shear, high q min (> 2.0), high bootstrap fraction, an H-mode pedestal, and varying shape parameters. The pressure profile is modeled by various polynomials together with a hyperbolic tangent pedestal, consistent with experimental observations. Stability is calculated with the DCON code and the resulting stability boundary is corroborated by GATO runs

  5. Effect of the number of electrodes on the reconstructed lung shape in electrical impedance tomography

    Directory of Open Access Journals (Sweden)

    Schullcke Benjamin

    2016-09-01

    Full Text Available Electrical impedance tomography (EIT is used to monitor the regional distribution of ventilation in a transversal plane of the thorax. In this manuscript we evaluate the impact of different quantities of electrodes used for current injection and voltage measurement on the reconstructed shape of the lungs. Results indicate that the shape of reconstructed impedance changes in the body depends on the number of electrodes. In this manuscript, we demonstrate that a higher number of electrodes do not necessarily increase the image quality. For the used stimulation pattern, utilizing neighboring electrodes for current injection and voltage measurement, we conclude that the shape of the lungs is best reconstructed if 16 electrodes are used.

  6. The ferromagnetic shape-memory effect in Ni-Mn-Ga

    International Nuclear Information System (INIS)

    Marioni, M.A.; O'Handley, R.C.; Allen, S.M.; Hall, S.R.; Paul, D.I.; Richard, M.L.; Feuchtwanger, J.; Peterson, B.W.; Chambers, J.M.; Techapiesancharoenkij, R.

    2005-01-01

    Active materials have long been used in the construction of sensors and devices. Examples are piezo-electric ceramics and shape memory alloys. The more recently developed ferromagnetic shape-memory alloys (FSMAs) have received considerable attention due to their large magnetic field-induced, reversible strains (up to 10%). In this article, we review the basic physical characteristics of the FSMA Ni-Mn-Ga (crystallography, thermal, mechanical and magnetic behavior). Also, we present some of the works currently under way in the areas of pulse-field and acoustic-assisted actuation, and vibration energy absorption

  7. The Effect of Tool Pin Shape of Friction Stir Welding (FSW) on Polypropylene

    Science.gov (United States)

    Nik, Z. C.; Ishak, M.; Othman, N. H.

    2017-09-01

    This experiment deals with similar joining of polypropylene (PP) with thickness of 3 mm was carried out by using friction stir welding (FSW) technique. The process parameters, rotational speed, welding speed and tilt angle were fixed of experiments. The tool geometry shapes were the main parameters which were taken into consideration. The optimum designs of tool geometry shape were determined with reference to tensile strength of the joint. During the tensile testing experiment, the results show that all fractured occurs in the heat-affected zone (HAZ) on the polypropylene (PP). Results show that the optimum design can be obtained with same rotational speed, welding speed and tilt angle.

  8. Strain characterization of fin-shaped field effect transistors with SiGe stressors using nanobeam electron diffraction

    International Nuclear Information System (INIS)

    Kim, Sun-Wook; Byeon, Dae-Seop; Jang, Hyunchul; Koo, Sang-Mo; Ko, Dae-Hong; Lee, Hoo-Jeong

    2014-01-01

    This study undertook strain analysis on fin-shaped field effect transistor structures with epitaxial Si 1−x Ge x stressors, using nano-beam electron diffraction and finite elements method. Combining the two methods disclosed dynamic strain distribution in the source/drain and channel region of the fin structure, and the effects of dimensional factors such as the stressor thickness and fin width, offering valuable information for device design.

  9. Strain characterization of fin-shaped field effect transistors with SiGe stressors using nanobeam electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun-Wook; Byeon, Dae-Seop; Jang, Hyunchul; Koo, Sang-Mo; Ko, Dae-Hong, E-mail: dhko@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Hoo-Jeong, E-mail: hlee@skku.edu [Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-08-25

    This study undertook strain analysis on fin-shaped field effect transistor structures with epitaxial Si{sub 1−x}Ge{sub x} stressors, using nano-beam electron diffraction and finite elements method. Combining the two methods disclosed dynamic strain distribution in the source/drain and channel region of the fin structure, and the effects of dimensional factors such as the stressor thickness and fin width, offering valuable information for device design.

  10. [EFFECTIVENESS OF ADVANCED SKIN FLAP AND V-SHAPED VENTRAL INCISION ALONG THE ROOT OF PENILE SHAFT FOR CONCEALED PENIS].

    Science.gov (United States)

    Lin, Junshan; Li, Dumiao; Zhang, Jianxing; Wu, Qiang; Xu, Yali; Lin, Li

    2015-09-01

    To investigate effectiveness of advanced skin flap and V-shaped ventral incision along the root of penile shaft for concealed penis in children. Between July 2007 and January 2015, 121 boys with concealed penis were treated with advanced skin flap and V-shaped ventral incision along the root of penile shaft. The age varied from 18 months to 13 years (mean, 7.2 years). Repair was based on a vertical incision in median raphe, complete degloving of penis and tacking its base to the dermis of the skin. Advanced skin flap and a V-shaped ventral incision along the root of penile shaft were used to cover the penile shaft. The operation time ranged from 60 to 100 minutes (mean, 75 minutes). Disruption of wound occurred in 1 case, and was cured after dressing change; and primary healing of incision was obtained in the others. The follow-up period ranged from 3 months to 7 years (median, 24 months). All patients achieved good to excellent cosmetic results with a low incidence of complications. The results were satisfactory in exposure of penis and prepuce appearance. No obvious scar was observed. The penis had similar appearance to that after prepuce circumcision. A combination of advanced skin flap and V-shaped ventral incision along the root of penile shaft is a simple, safe, and effective procedure for concealed penis with a similar appearance result to the prepuce circumcision.

  11. Effects of Processing Parameters on the Forming Quality of C-Shaped Thermosetting Composite Laminates in Hot Diaphragm Forming Process

    Science.gov (United States)

    Bian, X. X.; Gu, Y. Z.; Sun, J.; Li, M.; Liu, W. P.; Zhang, Z. G.

    2013-10-01

    In this study, the effects of processing temperature and vacuum applying rate on the forming quality of C-shaped carbon fiber reinforced epoxy resin matrix composite laminates during hot diaphragm forming process were investigated. C-shaped prepreg preforms were produced using a home-made hot diaphragm forming equipment. The thickness variations of the preforms and the manufacturing defects after diaphragm forming process, including fiber wrinkling and voids, were evaluated to understand the forming mechanism. Furthermore, both interlaminar slipping friction and compaction behavior of the prepreg stacks were experimentally analyzed for showing the importance of the processing parameters. In addition, autoclave processing was used to cure the C-shaped preforms to investigate the changes of the defects before and after cure process. The results show that the C-shaped prepreg preforms with good forming quality can be achieved through increasing processing temperature and reducing vacuum applying rate, which obviously promote prepreg interlaminar slipping process. The process temperature and forming rate in hot diaphragm forming process strongly influence prepreg interply frictional force, and the maximum interlaminar frictional force can be taken as a key parameter for processing parameter optimization. Autoclave process is effective in eliminating voids in the preforms and can alleviate fiber wrinkles to a certain extent.

  12. The effect of spatial light modulator (SLM) dependent dispersion on spatial beam shaping

    CSIR Research Space (South Africa)

    Spangenberg, D-M

    2013-08-01

    Full Text Available on the pixels between zero and two pi for a specific wavelength. It is therefore unavoidable when using the same SLM, to do beam shaping of a source which emits multiple wavelengths or a wide bandwidth, that the device will not modulate all wavelengths between...

  13. Study on Effects of The Shape of Cavitator on Supercavitation Flow Field Characteristics

    Science.gov (United States)

    Wang, Rui; Dang, Jianjun; Yao, Zhong

    2018-03-01

    The cavitator is the key part of the nose of the vehicle to induce the formation of supercavity, which has an important influence in the cavity formation rate, cavity shape and cavity stability. To study the influence of the shape on the supercavitation flew field characteristics, the cavity characteristics and the resistance characteristics of different shapes of cavitator under different working conditions are obtained by combining technical methods of numerical simulation and experimental research in water tunnel. The simulation results are contrast and analyzed with the test results. The analysis results show that : in terms of the cavity size, the inverted-conic cavitator can form the biggest cavity size, followed by the disk cavitator, and the truncated-conic cavitator is the least; in terms of the cavity formation speed, the inverted-conic cavitator has the fastest cavity formation speed, then is the truncated-conic cavitator, and the disk cavitator is the least; in terms of the drag characteristic, the truncated-conic cavitator has the maximum coefficient, disk cavitator is the next, the inverted-conic cavitator is the minimal. The research conclusion can provide reference and basis for the head shape design of supercavitating underwater ordnance and the design of hydrodynamic layout.

  14. Effect of kibble size, shape and additives on plaque in cats

    NARCIS (Netherlands)

    Clarke, D.E.; Servet, E.; Hendriks, W.H.; Thomas, D.G.; Weidgraaf, K.; Biourge, V.C.

    2010-01-01

    Forty mixed-breed cats completed a parallel-group, clinical study to compare supragingival plaque accumulation using a triangular or rectangular shaped dry-expanded diet, with or without an anti-calculus agent (sodium tripolyphosphate) or an anti-plaque agent (plaquereducing nutrient). The cats were

  15. Affordances shape pass kick behavior in association football : effects of distance and social context

    NARCIS (Netherlands)

    Pepping, Gert-Jan; Heijmerikx, Johan; de Poel, Harjo J.

    2011-01-01

    A prerequisite for accurate passing in association football is that a player perceives the affordances, that is, the opportunities for action, of a given situation. The present study examined how affordances shape passing in association football by comparing the performance of pass-kicks in two task

  16. Evidence for cluster shape effects on the kinetic energy spectrum in thermionic emission.

    Science.gov (United States)

    Calvo, F; Lépine, F; Baguenard, B; Pagliarulo, F; Concina, B; Bordas, C; Parneix, P

    2007-11-28

    Experimental kinetic energy release distributions obtained for the thermionic emission from C(n) (-) clusters, 10theory, these different features are analyzed and interpreted as the consequence of contrasting shapes in the daughter clusters; linear and nonlinear isomers have clearly distinct signatures. These results provide a novel indirect structural probe for atomic clusters associated with their thermionic emission spectra.

  17. Effect on injuries of assigning shoes based on foot shape in air force basic training.

    Science.gov (United States)

    Knapik, Joseph J; Brosch, Lorie C; Venuto, Margaret; Swedler, David I; Bullock, Steven H; Gaines, Lorraine S; Murphy, Ryan J; Tchandja, Juste; Jones, Bruce H

    2010-01-01

    This study examined whether assigning running shoes based on the shape of the bottom of the foot (plantar surface) influenced injury risk in Air Force Basic Military Training (BMT) and examined risk factors for injury in BMT. Data were collected from BMT recruits during 2007; analysis took place during 2008. After foot examinations, recruits were randomly consigned to either an experimental group (E, n=1042 men, 375 women) or a control group (C, n=913 men, 346 women). Experimental group recruits were assigned motion control, stability, or cushioned shoes for plantar shapes indicative of low, medium, or high arches, respectively. Control group recruits received a stability shoe regardless of plantar shape. Injuries during BMT were determined from outpatient visits provided from the Defense Medical Surveillance System. Other injury risk factors (fitness, smoking, physical activity, prior injury, menstrual history, and demographics) were obtained from a questionnaire, existing databases, or BMT units. Multivariate Cox regression controlling for other risk factors showed little difference in injury risk between the groups among men (hazard ratio [E/C]=1.11, 95% CI=0.89-1.38) or women (hazard ratio [E/C]=1.20, 95% CI= 0.90-1.60). Independent injury risk factors among both men and women included low aerobic fitness and cigarette smoking. This prospective study demonstrated that assigning running shoes based on the shape of the plantar surface had little influence on injury risk in BMT even after controlling for other injury risk factors. Published by Elsevier Inc.

  18. The effects of phase on the perception of 3D shape from texture: psychophysics and modeling.

    NARCIS (Netherlands)

    Thaler, L.; Todd, J.T.; Dijkstra, T.M.H.

    2007-01-01

    Two experiments are reported in which observers judged the apparent shapes of elliptical cylinders with eight different textures that were presented with scrambled and unscrambled phase spectra. The results revealed that the apparent depths of these surfaces varied linearly with the ground truth in

  19. Digital liquid-scintillation counting and effective pulse-shape discrimination with artificial neural networks

    International Nuclear Information System (INIS)

    Langrock, Gert; Wiehl, Norbert; Kling, Hans-Otto; Mendel, Matthias; Naehler, Andrea; Tharun, Udo; Eberhardt, Klaus; Trautmann, Norbert; Kratz, Jens Volker

    2015-01-01

    A typical problem in low-level liquid scintillation (LS) counting is the identification of α particles in the presence of a high background of β and γ particles. Especially the occurrence of β-β and β-γ pile-ups may prevent the unambiguous identification of an α signal by commonly used analog electronics. In this case, pulse-shape discrimination (PSD) and pile-up rejection (PUR) units show an insufficient performance. This problem was also observed in own earlier experiments on the chemical behaviour of transactinide elements using the liquid-liquid extraction system SISAK in combination with LS counting. α-particle signals from the decay of the transactinides could not be unambiguously assigned. However, the availability of instruments for the digital recording of LS pulses changes the situation and provides possibilities for new approaches in the treatment of LS pulse shapes. In a SISAK experiment performed at PSI, Villigen, a fast transient recorder, a PC card with oscilloscope characteristics and a sampling rate of 1 giga samples s -1 (1 ns per point), was used for the first time to record LS signals. It turned out, that the recorded signals were predominantly α β-β and β-γ pile up, and fission events. This paper describes the subsequent development and use of artificial neural networks (ANN) based on the method of 'back-propagation of errors' to automatically distinguish between different pulse shapes. Such networks can 'learn' pulse shapes and classify hitherto unknown pulses correctly after a learning period. The results show that ANN in combination with fast digital recording of pulse shapes can be a powerful tool in LS spectrometry even at high background count rates.

  20. Digital liquid-scintillation counting and effective pulse-shape discrimination with artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Langrock, Gert; Wiehl, Norbert; Kling, Hans-Otto; Mendel, Matthias; Naehler, Andrea; Tharun, Udo; Eberhardt, Klaus; Trautmann, Norbert; Kratz, Jens Volker [Mainz Univ. (Germany). Inst. fuer Kernchemie; Omtvedt, Jon-Petter [Oslo Univ. (Norway). Dept. of Chemistry; Skarnemark, Gunnar [Chalmers Univ. of Technology, Goeteborg (Sweden)

    2015-05-01

    A typical problem in low-level liquid scintillation (LS) counting is the identification of α particles in the presence of a high background of β and γ particles. Especially the occurrence of β-β and β-γ pile-ups may prevent the unambiguous identification of an α signal by commonly used analog electronics. In this case, pulse-shape discrimination (PSD) and pile-up rejection (PUR) units show an insufficient performance. This problem was also observed in own earlier experiments on the chemical behaviour of transactinide elements using the liquid-liquid extraction system SISAK in combination with LS counting. α-particle signals from the decay of the transactinides could not be unambiguously assigned. However, the availability of instruments for the digital recording of LS pulses changes the situation and provides possibilities for new approaches in the treatment of LS pulse shapes. In a SISAK experiment performed at PSI, Villigen, a fast transient recorder, a PC card with oscilloscope characteristics and a sampling rate of 1 giga samples s{sup -1} (1 ns per point), was used for the first time to record LS signals. It turned out, that the recorded signals were predominantly α β-β and β-γ pile up, and fission events. This paper describes the subsequent development and use of artificial neural networks (ANN) based on the method of 'back-propagation of errors' to automatically distinguish between different pulse shapes. Such networks can 'learn' pulse shapes and classify hitherto unknown pulses correctly after a learning period. The results show that ANN in combination with fast digital recording of pulse shapes can be a powerful tool in LS spectrometry even at high background count rates.

  1. Influence of aging and thermomechanical cycling on the magnetostriction and magnetic shape memory effect in martensitic alloy

    International Nuclear Information System (INIS)

    L’vov, Victor A; Kosogor, Anna; Barandiaran, Jose M; Chernenko, Volodymyr A

    2015-01-01

    An influence of internal stress created by the crystal defects on the magnetically induced reorientation (MIR) of martensite variants in the ferromagnetic shape memory alloy (FSMA) has been analyzed. Using the internal stress conception, a noticeable influence of the spatial reconfiguration of crystal defects on the ordinary magnetostriction of FSMA and magnetic shape memory (MSM) effect has been predicted. It has been shown that the defect reconfiguration, which stabilizes the martensitic phase during martensite aging, increases the shear elastic modulus. The increase of shear modulus reduces the magnetostriction value and in this way suppresses the MSM effect. The magneto-thermo-mechanical training of aged alloys destabilizes the martensitic phase, restores the initial magnetostriction value, and promotes the MSM effect. (paper)

  2. Integration of tomato reproductive developmental landmarks and expression profiles, and the effect of SUN on fruit shape

    Directory of Open Access Journals (Sweden)

    Li Dongmei

    2009-05-01

    Full Text Available Abstract Background Universally accepted landmark stages are necessary to highlight key events in plant reproductive development and to facilitate comparisons among species. Domestication and selection of tomato resulted in many varieties that differ in fruit shape and size. This diversity is useful to unravel underlying molecular and developmental mechanisms that control organ morphology and patterning. The tomato fruit shape gene SUN controls fruit elongation. The most dramatic effect of SUN on fruit shape occurs after pollination and fertilization although a detailed investigation into the timing of the fruit shape change as well as gene expression profiles during critical developmental stages has not been conducted. Results We provide a description of floral and fruit development in a red-fruited closely related wild relative of tomato, Solanum pimpinellifolium accession LA1589. We use established and propose new floral and fruit landmarks to present a framework for tomato developmental studies. In addition, gene expression profiles of three key stages in floral and fruit development are presented, namely floral buds 10 days before anthesis (floral landmark 7, anthesis-stage flowers (floral landmark 10 and fruit landmark 1, and 5 days post anthesis fruit (fruit landmark 3. To demonstrate the utility of the landmarks, we characterize the tomato shape gene SUN in fruit development. SUN controls fruit shape predominantly after fertilization and its effect reaches a maximum at 8 days post-anthesis coinciding with fruit landmark 4 representing the globular embryo stage of seed development. The expression profiles of the NILs that differ at sun show that only 34 genes were differentially expressed and most of them at a less than 2-fold difference. Conclusion The landmarks for flower and fruit development in tomato were outlined and integrated with the effect of SUN on fruit shape. Although we did not identify many genes differentially expressed in

  3. Shape memory alloys

    International Nuclear Information System (INIS)

    Kaszuwara, W.

    2004-01-01

    Shape memory alloys (SMA), when deformed, have the ability of returning, in certain circumstances, to their initial shape. Deformations related to this phenomenon are for polycrystals 1-8% and up to 15% for monocrystals. The deformation energy is in the range of 10 6 - 10 7 J/m 3 . The deformation is caused by martensitic transformation in the material. Shape memory alloys exhibit one directional or two directional shape memory effect as well as pseudoelastic effect. Shape change is activated by temperature change, which limits working frequency of SMA to 10 2 Hz. Other group of alloys exhibit magnetic shape memory effect. In these alloys martensitic transformation is triggered by magnetic field, thus their working frequency can be higher. Composites containing shape memory alloys can also be used as shape memory materials (applied in vibration damping devices). Another group of composite materials is called heterostructures, in which SMA alloys are incorporated in a form of thin layers The heterostructures can be used as microactuators in microelectromechanical systems (MEMS). Basic SMA comprise: Ni-Ti, Cu (Cu-Zn,Cu-Al, Cu-Sn) and Fe (Fe-Mn, Fe-Cr-Ni) alloys. Shape memory alloys find applications in such areas: automatics, safety and medical devices and many domestic appliances. Currently the most important appears to be research on magnetic shape memory materials and high temperature SMA. Vital from application point of view are composite materials especially those containing several intelligent materials. (author)

  4. Analyzing the shape parameter effects on the performance of the mixed-flow fan using CFD and Factorial design

    International Nuclear Information System (INIS)

    Jung, Uk Hee; Kim, Joon Hyung; Kim, Sung; Kim, Jin Hyuk; Choi, Young Seok

    2016-01-01

    Fans are representative turbo-machinery widely used for ventilation throughout the industrial world. Recently, as the importance of energy saving has been magnified with the fans, the demand for the fans with high efficiency and performance has been increasing. The representative method for enhancing the performance includes design optimization; in practice, fan performance can be improved by changing the shape parameters such as those of meridional plane, impeller, and diffuser. Before optimizing the efficient design, a process of screening to select important design parameters is essential. The present study aimed to analyze the effects of mixed-flow fans' shape parameters on fan performance (static pressure and fan static efficiency) and derive optimum models based on the results. In this study, the shape parameters considered in the impeller domain are as follows: tip clearance, number of blades, beta angle of Leading edge (LE) in the blade, and beta angle of Trailing edge (TE) in the blade. The shape parameters considered in the diffuser domain are as follows: meridional length of the Guide vane (GV), number of GV, beta angle of LE in the GV and beta angle of TE in the GV. The effects of individual shape parameters were analyzed using the CFD (Computational fluid dynamic) and DOE (Design of experiments) methods. The reliability of CFD was verified through the comparison between preliminary fan model's experiment results and CFD results, and screening processes were implemented through 24-1 fractional factorial design. From the analysis of DOE results, it could be seen that the tip clearance and the number of blades in the impeller domain greatly affected the fan performance, and the beta angle of TE at the GV in the diffuser domain greatly affected the fan performance. Finally, the optimum models with improved fan performance were created using linear regression equations derived from 24-1 fractional factorial design.

  5. Spray forming of Cu–11.85Al–3.2Ni–3Mn (wt%) shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Cava, Régis D., E-mail: regis_cava@hotmail.com [Department of Materials Engineering, Federal University of São Carlos, São Carlos (Brazil); Bolfarini, Claudemiro; Kiminami, Cláudio S. [Department of Materials Engineering, Federal University of São Carlos, São Carlos (Brazil); Mazzer, Eric M. [Postgraduate Program in Materials Science and Engineering, Federal University of São Carlos (Brazil); Botta Filho, Walter J. [Department of Materials Engineering, Federal University of São Carlos, São Carlos (Brazil); Gargarella, Piter; Eckert, Jürger [IFW Dresden, Institute for Complex Materials, Dresden (Germany)

    2014-12-05

    Highlights: • We characterized a Cu-based shape memory alloy produced by spray forming. • The deposit presented equiaxial grains and monoclinic martensite β′ microstructure. • The deposit’s shape memory properties varied as a function of the cooling rates. • The results opened a new window in the manufacture of Cu shape memory materials. - Abstract: Cu-based shape memory alloys (SMA) in the range of Cu–(11.8–13.5)Al–(3.2–4)Ni–(2–3)Mn (wt%) exhibit high thermal and electrical conductivity, combine good mechanical properties with a pronounced shape memory effect, and are low cost (Dutkiewicz et al., 1999). Their processing requires high cooling rates to reduce grain size, prevent decomposition of the ß phase into equilibrium phases, and induce martensite transformation. In this investigation, Cu–11.85Al–3.2Ni–3Mn (wt%) shape memory alloy was processed by spray forming, a rapid solidification technique that involves cooling rates of 10{sup 1} to 10{sup 4} K/s, to determine the potential of producing deposits with adequate microstructure, homogeneity and porosity for the manufacture of SMA near net shape parts. To this end, 5.2 kg of alloy with nominal composition was atomized with nitrogen gas under a pressure of 0.5 MPa and a gas–metal ratio (GMR) of 1.93. The atomized material was deposited at 60 rpm on a rotating steel substrate positioned 350 mm below the gas nozzle. The microstructure of the deposit was characterized by optical and scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. The deposit with an effective diameter of 240 mm and 75 mm height presented equiaxial grains with a martensite microstructure. Grain sizes varied from 25 μm in the lower region (contact with the steel substrate) to 160 μm in the upper region of the deposit. Measurements of the reverse martensite transformation temperature of the deposit in different regions revealed its strong influence on the grain size.

  6. Synergistic effect of Ag nanoparticle-decorated graphene oxide and carbon fiber on electrical actuation of polymeric shape memory nanocomposites

    International Nuclear Information System (INIS)

    Lu, Haibao; Leng, Jinsong; Du, Shanyi; Liang, Fei; Gou, Jihua

    2014-01-01

    This study reports an effective approach of significantly improving electrical properties and recovery performance of shape memory polymer (SMP) nanocomposite, of which its shape recovery was triggered by electrically resistive Joule heating. Reduced graphene oxide (GOs) self-assembled and grafted onto carbon fiber, were used to enhance the interfacial bonding with the SMP matrix via van der Waals force and covalent bond, respectively. A layer of Ag nanoparticles was synthesized from Ag + solution and chemically deposited onto GO assemblies. These Ag nanoparticles were expected to bridge the gap between GO and improve the electrical conductivity. The experimental results reveal that the electrical conductivity of the SMP nanocomposite was significantly improved via the synergistic effect between Ag nanoparticle-decorated GO and carbon fiber. Finally, the electrically induced shape memory effect of the SMP nanocomposite was achieved, and the temperature distribution in the SMP nanocomposites was recorded and monitored. An effective approach was demonstrated to produce the electro-activated SMP nanocomposites and the resistive Joule heating was viable at a low electrical voltage below 10 V. (paper)

  7. Effects of thermo-mechanical behavior and hinge geometry on folding response of shape memory polymer sheets

    Science.gov (United States)

    Mailen, Russell W.; Dickey, Michael D.; Genzer, Jan; Zikry, Mohammed

    2017-11-01

    Shape memory polymer (SMP) sheets patterned with black ink hinges change shape in response to external stimuli, such as absorbed thermal energy from an infrared (IR) light. The geometry of these hinges, including size, orientation, and location, and the applied thermal loads significantly influence the final folded shape of the sheet, but these variables have not been fully investigated. We perform a systematic study on SMP sheets to fundamentally understand the effects of single and double hinge geometries, hinge orientation and spacing, initial temperature, heat flux intensity, and pattern width on the folding behavior. We have developed thermo-viscoelastic finite element models to characterize and quantify the stresses, strains, and temperatures as they relate to SMP shape changes. Our predictions indicate that hinge orientation can be used to reduce the total bending angle, which is the angle traversed by the folding face of the sheet. Two parallel hinges increase the total bending angle, and heat conduction between the hinges affects the transient folding response. IR intensity and initial temperatures can also influence the transient folding behavior. These results can provide guidelines to optimize the transient folding response and the three-dimensional folded structure obtained from self-folding polymer origami sheets that can be applied for myriad applications.

  8. On the effect of cross sectional shape on incipient motion and deposition of sediments in fixed bed channels

    Directory of Open Access Journals (Sweden)

    Safari Mir-Jafar-Sadegh

    2014-03-01

    Full Text Available The condition of incipient motion and deposition are of the essential issues for the study of sediment transport. This phenomenon is of great importance to hydraulic engineers for designing sewers, drainage, as well as other rigid boundary channels. This is a study carried out with the objectives of describing the effect of cross-sectional shape on incipient motion and deposition of particles in rigid boundary channels. In this research work, the experimental data given by Loveless (1992 and Mohammadi (2005 are used. On the basis of the critical velocity approach, a new incipient motion equation for a V-shaped bottom channel and incipient deposition of sediment particles equations for rigid boundary channels having circular, rectangular, and U-shaped cross sections are obtained. New equations were compared to the other incipient motion equations. The result shows that the cross-sectional shape is an important factor for defining the minimum velocity for no-deposit particles. This study also distinguishes incipient motion of particles from incipient deposition for particles. The results may be useful for designing fixed bed channels with a limited deposition condition.

  9. Shape effects on time-scale divergence at athermal jamming transition of frictionless non-spherical particles

    Science.gov (United States)

    Yuan, Ye; Jin, Weiwei; Liu, Lufeng; Li, Shuixiang

    2017-10-01

    The critical behaviors of a granular system at the jamming transition have been extensively studied from both mechanical and thermodynamic perspectives. In this work, we numerically investigate the jamming behaviors of a variety of frictionless non-spherical particles, including spherocylinder, ellipsoid, spherotetrahedron and spherocube. In particular, for a given particle shape, a series of random configurations at different fixed densities are generated and relaxed to minimize interparticle overlaps using the relaxation algorithm. We find that as the jamming point (i.e., point J) is approached, the number of iteration steps (defined as the "time-scale" for our systems) required to completely relax the interparticle overlaps exhibits a clear power-law divergence. The dependence of the detailed mathematical form of the power-law divergence on particle shapes is systematically investigated and elucidated, which suggests that the shape effects can be generally categorized as elongation and roundness. Importantly, we show the jamming transition density can be accurately determined from the analysis of time-scale divergence for different non-spherical shapes, and the obtained values agree very well with corresponding ones reported in literature. Moreover, we study the plastic behaviors of over-jammed packings of different particles under a compression-expansion procedure and find that the jamming of ellipsoid is much more robust than other non-spherical particles. This work offers an alternative approximate procedure besides conventional packing algorithms for studying athermal jamming transition in granular system of frictionless non-spherical particles.

  10. Environmental effects on the shape variation of male ultraviolet patterns in the Brimstone butterfly ( Gonepteryx rhamni, Pieridae, Lepidoptera)

    Science.gov (United States)

    Pecháček, Pavel; Stella, David; Keil, Petr; Kleisner, Karel

    2014-12-01

    The males of the Brimstone butterfly ( Gonepteryx rhamni) have ultraviolet pattern on the dorsal surfaces of their wings. Using geometric morphometrics, we have analysed correlations between environmental variables (climate, productivity) and shape variability of the ultraviolet pattern and the forewing in 110 male specimens of G. rhamni collected in the Palaearctic zone. To start with, we subjected the environmental variables to principal component analysis (PCA). The first PCA axis (precipitation, temperature, latitude) significantly correlated with shape variation of the ultraviolet patterns across the Palaearctic. Additionally, we have performed two-block partial least squares (PLS) analysis to assess co-variation between intraspecific shape variation and the variation of 11 environmental variables. The first PLS axis explained 93 % of variability and represented the effect of precipitation, temperature and latitude. Along this axis, we observed a systematic increase in the relative area of ultraviolet colouration with increasing temperature and precipitation and decreasing latitude. We conclude that the shape variation of ultraviolet patterns on the forewings of male Brimstones is correlated with large-scale environmental factors.

  11. Suppressive and Enhancing Effects in Early Visual Cortex during Illusory Shape Perception: A Comment on Kok and de Lange (2014

    Directory of Open Access Journals (Sweden)

    Pieter Moors

    2015-02-01

    Full Text Available In a recent functional magnetic resonance imaging study, Kok and de Lange (2014 observed that BOLD activity for a Kanizsa illusory shape stimulus, in which pacmen-like inducers elicit an illusory shape percept, was either enhanced or suppressed relative to a nonillusory control configuration depending on whether the spatial profile of BOLD activity in early visual cortex was related to the illusory shape or the inducers, respectively. The authors argued that these findings fit well with the predictive coding framework, because top-down predictions related to the illusory shape are not met with bottom-up sensory input and hence the feedforward error signal is enhanced. Conversely, for the inducing elements, there is a match between top-down predictions and input, leading to a decrease in error. Rather than invoking predictive coding as the explanatory framework, the suppressive effect related to the inducers might be caused by neural adaptation to perceptually stable input due to the trial sequence used in the experiment.

  12. A Spiral in the Heart: Mitral Valve Endocarditis with Unusual Vegetation Shape Potentially Affecting Effectiveness of Antibiotic Therapy

    Directory of Open Access Journals (Sweden)

    Veronica Fibbi

    2015-01-01

    Full Text Available We report an unusual case of infective endocarditis (IE in an 88-year-old woman, occurring on a prolapsing mitral valve and characterized by an atypical vegetation shape resembling a spiral-like appearance. After the patient refused surgical correction, persistent IE despite prolonged antibiotic therapy was observed, resulting in an ischemic stroke probably secondary to septic embolus. The importance of vegetation shape in the management of patients with IE was classically related to the increased risk of embolization associated with pedunculated, irregular, and multilobed masses. We hypothesize that the unusual spiral-like vegetation shape in our patient may have favored IE persistence by two mechanisms, namely, a decrease of the exposed vegetation surface with creation of an internal core where the penetration of antimicrobial agents was obstacled and the creation of blood turbulence within the vegetation preventing a prolonged contact with circulating antibiotics. These considerations suggest that vegetation shape might be considered of importance in patients with IE not only because of its classical association with embolization risk, but also because of its potential effect on the efficacy of antibiotic therapy.

  13. P-phase precipitation and its effect on martensitic transformation in (Ni,Pt)Ti shape memory alloys

    International Nuclear Information System (INIS)

    Gao, Y.; Zhou, N.; Yang, F.; Cui, Y.; Kovarik, L.; Hatcher, N.; Noebe, R.; Mills, M.J.; Wang, Y.

    2012-01-01

    A new precipitate phase named P-phase has recently been identified in (Ni,Pt)Ti high temperature shape memory alloys. In order to understand the roles played by the fine coherent P-phase precipitates in determining the martensitic transformation temperature (M s ), strength of the B2 matrix phase, dimensional stability and shape memory effect of the alloys, a phase field model of P-phase precipitation is developed. Model inputs, including lattice parameters, precipitate–matrix orientation relationship, elastic constants and free energy data, are obtained from experimental characterization, ab initio calculations and thermodynamic databases. Through computer simulations, the shape and spatial distribution of the P-phase precipitates, as well as the compositional and stress fields around them, are quantitatively determined. On this basis, the elastic interaction energy between the P-phase precipitates and a martenstic nucleus is calculated. It is found that both the chemical non-uniformity and stress field associated with the P-phase precipitates are in favor of the martensitic transformation. Their relative contributions to the increase in M s temperature are quantified as a function of aging time and the result seems to agree with the experimental measurements. The shape and spatial distribution of the P-phase precipitates predicted by the simulations also agree well with experimental observations.

  14. Effect of shape and size of amidoxime-group-containing adsorbent on the recovery of uranium from sea water

    International Nuclear Information System (INIS)

    Omichi, H.; Kataki, A.; Sugo, T.; Okamoto, J.; Katoh, S.; Sakane, K.; Sugasaka, K.; Itagaki, T.

    1987-01-01

    An amidoxime-group-containing adsorbent for the recovery of uranium from sea water was synthesized by radiation-induced graft polymerization of acrylonitrile onto polypropylene fiber of round and cross-shaped sections. The tensile strength and elongation of the synthesized adsorbent, both of which were one-half those of the raw material, were not affected by the shape of the fiber. The deterioration of the adsorption ability induced by immersing the adsorbent in HCl was negligible because of the short immersion time required for the desorption with HCl. The concentration factors for uranium and transition metals in 28 days were in the order of 10 5 , while those for alkali metals and alkaline earth metals were in the order 10 -1 -10 1 . The recovery of uranium with the cross-shaped adsorbent was superior to that of the round-shaped one. XMA line profiles show that the distribution of uranium is much restricted to the surface layer when compared with that of alkaline earth metals. Diminishing the diameter or increasing the surface area was effective for increasing the adsorption of uranium

  15. Effects of the shape properties of talc and quartz particles on the wettability based separation processes

    International Nuclear Information System (INIS)

    Hicyilmaz, C.; Ulusoy, U.; Yekeler, M.

    2004-01-01

    Shape properties of talc and quartz particles ground by a laboratory size ball, rod, and autogenous mills were studied using scanning electron microscope (SEM). More than 100 particles were measured to do the shape analysis of each mill product. The wettability behavior of (γ c ) a highly hydrophobic of talc mineral was determined by contact angle measurements and micro-flotation tests using a contact angle goniometer and EMDEE MicroFLOT test tube, respectively. On the other hand, wettability (γ c ) of quartz, which is a highly hydrophilic mineral, was determined by the micro-flotation method only. The results showed that the particles ground by rod mill gave higher flatness and elongation ratio, which meant higher hydrophobicity with lower γ c values in the separations by flotation method

  16. Pendant unit effect on electron tunneling in U-shaped molecules

    International Nuclear Information System (INIS)

    Liu Min; Chakrabarti, Subhasis; Waldeck, David H.; Oliver, Anna M.; Paddon-Row, Michael N.

    2006-01-01

    The electron transfer reactions of three U-shaped donor-bridge-acceptor molecules with different pendant groups have been studied in different solvents as a function of temperature. Analysis of the electron transfer kinetics in nonpolar and weakly polar solvents provides experimental reaction Gibbs energies that are used to parameterize a molecular solvation model. This solvation model is then used to predict energetic parameters in the electron transfer rate constant expression and allow the electronic coupling between the electron donor and electron acceptor groups to be determined from the rate data. The U-shaped molecules differ by alkylation of the aromatic pendant group, which lies in the 'line-of-sight' between the donor and acceptor groups. The findings show that the electronic coupling through the pendant group is similar for these molecules

  17. Symptoms Moderating the Association Between Recent Suicide Attempts and Trauma Levels: Fan-Shaped Effects.

    Science.gov (United States)

    Afzali, Mohammad H; Birmes, Philippe; Vautier, Stéphane

    2015-01-01

    The present study focuses on variables moderating the incidence of recent suicide attempt in a large community sample (n = 39,617) of French citizens with various levels of trauma. Five trauma levels were established based on posttraumatic stress disorder items of the Mini International Neuropsychiatric Interview. Twenty-three symptoms were examined as potential moderating variables with a fan-shaped pattern. Seven symptoms regarding desire for death, self-harm intention, suicidal ideation, lifetime suicide attempt, depressed mood, loss of interest, and panic attack exhibited the fan-shaped pattern. The absence of these moderating symptoms decreases the incidence of suicide attempt and their presence leads to a gradual increase.

  18. Effects of pore shape and porosity on the properties of porous LNKN ceramics as bone substitute

    International Nuclear Information System (INIS)

    Wang Qi; Chen Qiang; Zhu Jianguo; Huang Chunpeng; Darvell, Brian W.; Chen Zhiqing

    2008-01-01

    A porous lead-free piezoelectric ceramic is investigated as direct bone substitute. Porous lithium sodium potassium niobate (Li 0.06 Na 0.5 K 0.44 )NbO 3 specimens were prepared by pore-forming method. Different volume fraction of ammonium oxalate monohydrate and poly(methyl methacrylate) were used as porogens to obtain different pore shape and porosity. Scanning electron microscopy showed a bicontinuous 3-3 structure of interconnected pores 150-250 μm in size. The piezoelectric constants and electromechanical coupling coefficients may be controlled by both size and shape of the porogens to tune for the best biological response. Such materials show promise for use as a piezoelectric composite bone substitute

  19. Effect of shape and surface texture of aggregates during high intensity vertical shaft impact autogeneous crushing

    International Nuclear Information System (INIS)

    Samayamutthirian Palaniandy; Khairun Azizi Mohd Azizli

    2002-01-01

    The demand for quarry industry to produce high quality aggregates is increasing parallel with the demand of high strength concrete. Focus on the high quality aggregates production is very essential as 70% of the concrete consist of aggregates. High quality aggregate is characterised according to its shape, surface texture and its size distribution. The cubical and more equidimensional aggregates are characterised as high quality aggregates. Besides photomicrograph of aggregates, Flakiness and Elongation indices are important empirical measurements to determine the quality of the aggregates. The Barmac Rock On Rock Vertical Shaft Impactor proved that the shape of the aggregates can be improved by various crushing mechanisms as the EI and FI values were low and 75% of the cubical particles were observed in the crushed aggregates. (Author)

  20. Magnetic properties of Ni-Mn-Ga-Co-Cu tetragonal martensites exhibiting magnetic shape memory effect

    Czech Academy of Sciences Publication Activity Database

    Rameš, Michal; Heczko, Oleg; Sozinov, A.; Ullakko, K.; Straka, Ladislav

    2018-01-01

    Roč. 142, Jan (2018), s. 61-65 ISSN 1359-6462 R&D Projects: GA ČR GA16-00043S Institutional support: RVO:68378271 Keywords : ferromagnetic shape memory alloy * magnetic anisotropy * martensitic phase transformation * Heusler phases * twinning Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.747, year: 2016

  1. Ni–Mn–Ga single crystal exhibiting multiple magnetic shape memory effects

    Czech Academy of Sciences Publication Activity Database

    Heczko, Oleg; Veřtát, Petr; Vronka, Marek; Kopecký, Vít; Perevertov, Oleksiy

    2016-01-01

    Roč. 2, č. 3 (2016), s. 272-280 ISSN 2199-384X R&D Projects: GA ČR GB14-36566G; GA ČR GA15-00262S Institutional support: RVO:68378271 Keywords : magnetic shape memory * NiMnGa * stress-strain * twinning * magnetic field-induced transformation * magnetic field-induced reorientation Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. The pseudoelasticity and the shape memory effect in CoNiAl alloys

    Czech Academy of Sciences Publication Activity Database

    Kopeček, Jaromír; Jarošová, Markéta; Jurek, Karel; Heczko, Oleg

    2014-01-01

    Roč. 21, č. 1 (2014), s. 43-48 ISSN 1335-0803 R&D Projects: GA ČR(CZ) GA101/09/0702; GA ČR GAP107/10/0824; GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional support: RVO:68378271 Keywords : shape memory alloys * co-alloys * metallography * martensitic transition * stress induced martensite Subject RIV: BM - Solid Matter Physics ; Magnetism

  3. Asymmetric Deformation of Bubble Shape: Cause or Effect of Vortex-Shedding?

    Czech Academy of Sciences Publication Activity Database

    Wichterle, K.; Večeř, M.; Růžička, Marek

    2014-01-01

    Roč. 68, č. 1 (2014), s. 74-79 ISSN 0366-6352 R&D Projects: GA ČR GA104/07/1110 Grant - others:GA MŠMT(CZ) CZ.1.05/2.1.00/03.0082 Institutional support: RVO:67985858 Keywords : bubble * bubble shape * bubble velocity Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.468, year: 2014

  4. Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology.

    Science.gov (United States)

    Shin, Jae Man; Kim, YongJoo; Yun, Hongseok; Yi, Gi-Ra; Kim, Bumjoon J

    2017-02-28

    Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles. A distinct morphological transition from the ellipsoids with striped lamellae to the onion-like spheres was observed with decreasing evaporation rate. Experiments and dissipative particle dynamics (DPD) simulations showed that the evaporation rate affected the organization of BCPs at the particle surface, which determined the final shape and internal nanostructure of the particles. Differences in the solvent diffusion rates in PS and PB at rapid evaporation rates induced alignment of both domains perpendicular to the particle surface, resulting in ellipsoids with axial lamellar stripes. Slower evaporation rates provided sufficient time for BCP organization into onion-like structures with PB as the outermost layer, owing to the preferential interaction of PB with the surroundings. BCP molecular weight was found to influence the critical evaporation rate corresponding to the morphological transition from ellipsoid to onion-like particles, as well as the ellipsoid aspect ratio. DPD simulations produced morphologies similar to those obtained from experiments and thus elucidated the mechanism and driving forces responsible for the evaporation-induced assembly of BCPs into particles with well-defined shapes and morphologies.

  5. The effect of handedness on the shape of the central sulcus

    DEFF Research Database (Denmark)

    Sun, Zhong Yi; Klöppel, Stefan; Rivière, Denis

    2012-01-01

    Sinistrals differ from dextrals in the size of certain cortical folds. For instance, handedness has an impact on central sulcus surface area: the sulcus is larger in the dominant left hemisphere of dextrals and vice versa for sinistrals. However, the impact of handedness on the shape of the centr...... an accumulated record of both innate biases and early developmental experience. Characterizing normal variation of cortical morphology provides a means of systematically correlating behavior with cortical development....

  6. Ageing effects in a Cu-Al-Ni shape memory alloy

    Czech Academy of Sciences Publication Activity Database

    Daříček, Tomáš; Lašek, Jiří; Zárubová, Niva; Novák, Václav; Bartuška, Pavel

    2001-01-01

    Roč. 11, - (2001), s. Pr8-179-Pr8-184 ISSN 1155-4339 R&D Projects: GA AV ČR IAA1010909; GA AV ČR IAA1010817 Institutional research plan: CEZ:AV0Z1010914 Keywords : Cu-Al-Ni alloy * shape memory * martensitic transformation * resistometry Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.401, year: 2001

  7. Effect of the weld groove shape and pass number on residual stresses in butt-welded pipes

    International Nuclear Information System (INIS)

    Sattari-Far, I.; Farahani, M.R.

    2009-01-01

    This study used finite element techniques to analyze the thermo-mechanical behaviour and residual stresses in butt-welded pipes. The residual stresses were also measured in some welds by using the Hole-Drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on this study, a finite element modelling procedure with reasonable accuracy was developed. The developed FE modelling was used to study the effects of weld groove shape and weld pass number on welding residual stresses in butt-welded pipes. The hoop and axial residual stresses in pipe joints of 6 and 10 mm thickness of different groove shapes and pass number were studied. It is shown that these two parameters may have significant effects on magnitude and distribution of residual stresses in welded pipes.

  8. Orientation dependence of shape memory and super elastic effects in Ti-30% Ni-20% Cu single crystals

    International Nuclear Information System (INIS)

    Chumlyakov, Yu.I.; Kireeva, I.V.

    1999-01-01

    Single crystals of Ti-30% Ni-20% Cu (at.%) alloy experiencing B2-B19 martensitic transformation are used to study the dependence of deforming stress σ cr , shape memory effect and super elasticity on test temperature, crystal orientation and the sign of tension/compression stresses. It is shown that experimental values of shape memory effect and super elasticity as well as their dependences on orientation and loading regime are described within the frameworks of the model taking into account lattice distortions only. The orientation dependence and axial stress asymmetry in the temperature range of stress-induced martensite formation are determined by the dependence of lattice distortion during B2-B19 martensitic transformations on the orientation and the sign of applied stresses [ru

  9. Wetting layer effect on impurity-related electronic properties of different (In,Ga)N QD-shapes

    Science.gov (United States)

    El Ghazi, Haddou; Jorio, Anouar; Zorkani, Izeddine; Feddi, El Mustapha; El Mouchtachi, Ahmed

    2018-05-01

    In this paper, we have investigated the electronic properties of (In,Ga)N/GaN coupled wetting layer-quantum dot system using the numerical approach. The finite element method code is used to solve the Schrödinger equation, in the presence of the impurity. In our model, parallelepiped-shape, circular and square based-pyramidal and their wetting layers embedded in GaN matrix were considered. Based on the single band parabolic and the effective mass approximations, the envelop function and its corresponding energy eigenvalue are obtained assuming a finite potential barrier. Our results reveal that: (1) the wetting layer has a great influence on the electronic properties especially for a small quantum dot and acts in the opposite sense of the geometrical confinement, (2) a wetting layer-dependent critical QD-size is obtained limiting two different behaviors and (3) its effect is strongly-dependent on the quantum dot-shape.

  10. Investigation of Demagnetization Effect in an Interior V-Shaped Magnet Synchronous Motor at Dynamic and Static Conditions

    Directory of Open Access Journals (Sweden)

    F. Mahmouditabar

    2018-03-01

    Full Text Available Permanent magnet motors have been considered for a variety of applications due to their features such as high power density and high efficiency. One of the issues that should be investigated in the design of these motors is the demagnetization problem. Usually, the demagnetization analysis is carried out in a steady state, while demagnetization effect in dynamic condition is more considerable due to pulse shaped of armature field. Based on this fact, in this paper, dynamic demagnetization is investigated for an IPM V‑shaped magnet. This study has been done for two types of magnet, each one in static & dynamic conditions and the results are compared. Moreover, the effect of flux weakening regime on demagnetization is investigated.

  11. Growth of Au nanoparticle films and the effect of nanoparticle shape on plasmon peak wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Horikoshi, S., E-mail: horikoshi@sstl.info; Matsumoto, N.; Kato, T. [Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-8656 (Japan); Omata, Y. [Application and Technical Support, Elionix, Inc., 3-7-6 Motoyokoyama Hachioji, Tokyo 192-0063 (Japan)

    2014-05-21

    Metal nanoparticles (NPs) exhibit localized surface plasmon resonance (LSPR) and thus have potential for use in a wide range of applications. A facile technique for the preparation of NP films using an electron-cyclotron-resonance plasma sputtering method without a dewetting process is described. Field emission scanning electron microscopy (FE-SEM) observations revealed that the Au NPs grew independently as island-like particles during the first stage of sputtering and then coalesced with one another as sputtering time increased to ultimately form a continuous film. A plasmon absorption peak was observed via optical measurement of absorption efficiency. The LSPR peak shifted toward longer wavelengths (red shift) with an increase in sputtering time. The cause of this plasmon peak shift was theoretically investigated using the finite-difference time-domain calculation method. A realistic statistical distribution of the particle shapes based on FE-SEM observations was applied for the analysis, which has not been previously reported. It was determined that the change in the shape of the NPs from spheroidal to oval or slender due to coalescence with neighbouring NPs caused the LSPR peak shift. These results may enable the design of LSPR devices by controlling the characteristics of the nanoparticles, such as their size, shape, number density, and coverage.

  12. Effects of temporal integration on the shape of visual backward masking functions.

    Science.gov (United States)

    Francis, Gregory; Cho, Yang Seok

    2008-10-01

    Many studies of cognition and perception use a visual mask to explore the dynamics of information processing of a target. Especially important in these applications is the time between the target and mask stimuli. A plot of some measure of target visibility against stimulus onset asynchrony is called a masking function, which can sometimes be monotonic increasing but other times is U-shaped. Theories of backward masking have long hypothesized that temporal integration of the target and mask influences properties of masking but have not connected the influence of integration with the shape of the masking function. With two experiments that vary the spatial properties of the target and mask, the authors provide evidence that temporal integration of the stimuli plays a critical role in determining the shape of the masking function. The resulting data both challenge current theories of backward masking and indicate what changes to the theories are needed to account for the new data. The authors further discuss the implication of the findings for uses of backward masking to explore other aspects of cognition.

  13. The effect of alumina nanofillers size and shape on mechanical behavior of PMMA matrix composite

    Directory of Open Access Journals (Sweden)

    Ben Hasan Somaya Ahmed

    2014-01-01

    Full Text Available Composites with the addition of alumina nanofillers show improvement in mechanical properties. The PMMA polymer was used as a matrix and two different types of nanofillers, having extremely different shapes were added in the matrix to form the composite. Reinforcements were based on alumina nanoparticles having either spherical shape or whiskers having the length to diameter ratio of 100. The influence of alumina fillers size, shape and fillers loading on mechanical properties of prepared composite were studied using the nanoindentation measurements and dynamic mechanical analysis. It was observed that both alumina whiskers and alumina spherical nanoparticles added in the PMMA matrix improved the mechanical properties of the composite but the improvement was significantly higher with alumina whisker reinforcement. The concentration of the reinforcing alumina spherical nanoparticles and alumina whiskers in PMMA matrix varied up to 5 wt. %. The best performance was obtained by the addition of 3 wt. % of alumina whiskers in the PMMA matrix with regard to mechanical properties of the obtained composite.

  14. Growth of Au nanoparticle films and the effect of nanoparticle shape on plasmon peak wavelength

    Science.gov (United States)

    Horikoshi, S.; Matsumoto, N.; Omata, Y.; Kato, T.

    2014-05-01

    Metal nanoparticles (NPs) exhibit localized surface plasmon resonance (LSPR) and thus have potential for use in a wide range of applications. A facile technique for the preparation of NP films using an electron-cyclotron-resonance plasma sputtering method without a dewetting process is described. Field emission scanning electron microscopy (FE-SEM) observations revealed that the Au NPs grew independently as island-like particles during the first stage of sputtering and then coalesced with one another as sputtering time increased to ultimately form a continuous film. A plasmon absorption peak was observed via optical measurement of absorption efficiency. The LSPR peak shifted toward longer wavelengths (red shift) with an increase in sputtering time. The cause of this plasmon peak shift was theoretically investigated using the finite-difference time-domain calculation method. A realistic statistical distribution of the particle shapes based on FE-SEM observations was applied for the analysis, which has not been previously reported. It was determined that the change in the shape of the NPs from spheroidal to oval or slender due to coalescence with neighbouring NPs caused the LSPR peak shift. These results may enable the design of LSPR devices by controlling the characteristics of the nanoparticles, such as their size, shape, number density, and coverage.

  15. The Effect of Different Shape and Perforated rHDPE in Concrete Structures on Flexural Strength

    Science.gov (United States)

    Yuhazri, MY; Hafiz, KM; Myia, YZA; Jia, CP; Sihombing, H.; Sapuan, SM; Badarulzaman, NA

    2017-10-01

    This research was carried out to develop a reinforcing structure from recycled HDPE plastic lubricant containers to be embedded in concrete structure. Different forms and shapes of recycled HDPE plastic are designed as reinforcement incorporate with cement. In this study, the reinforcing structure was prepared by washing, cutting, dimensioning and joining of the waste HDPE containers (direct technique without treatment on plastic surface). Then, the rHDPE reinforced concrete was produced by casting based on standard of procedure in civil engineering technique. Eight different shapes of rHDPE in concrete structure were used to determine the concrete’s ability in terms of flexural strength. Embedded round shape in solid and perforated of rHDPE in concrete system drastically improved flexural strength at 17.78 % and 13.79 %. The result would seem that the concrete with reinforcing rHDPE structure exhibits a more gradual or flexible properties than concrete beams without reinforcement that has the properties of fragile.

  16. The effect of particle shape on cellular interaction and drug delivery applications of micro- and nanoparticles.

    Science.gov (United States)

    Jindal, Anil B

    2017-10-30

    Encapsulation of therapeutic agents in nanoparticles offers several benefits including improved bioavailability, site specific delivery, reduced toxicity and in vivo stability of proteins and nucleotides over conventional delivery options. These benefits are consequence of distinct in vivo pharmacokinetic and biodistribution profile of nanoparticles, which is dictated by the complex interplay of size, surface charge and surface hydrophobicity. Recently, particle shape has been identified as a new physical parameter which has exerted tremendous impact on cellular uptake and biodistribution, thereby in vivo performance of nanoparticles. Improved therapeutic efficacy of anticancer agents using non-spherical particles is the recent development in the field. Additionally, immunological response of nanoparticles was also altered when antigens were loaded in non-spherical nanovehicles. The apparent impact of particle shape inspired the new research in the field of drug delivery. The present review therefore details the research in this field. The review focuses on methods of fabrication of particles of non-spherical geometries and impact of particle shape on cellular uptake, biodistribution, tumor targeting and production of immunological responses. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Investigation of Size Effects to the Mixing Performance on the X-shaped Micro-Channels

    Directory of Open Access Journals (Sweden)

    S Tu

    2016-09-01

    Full Text Available Due to the developing of micro-electro-mechanical-system, MEMS, the fabrication of the microminiaturization devices becomes obviously important. The advances in the basic understanding of fluid physics have opened an era of application of fluid dynamics systems using microchannels. The purpose of this study is to research the flow transport phenomenon by employing different kinds of micro-channel sizing in X-shaped micro-channels. As the working fluid, water is injected to microchannel at different mass flow rate. Over a wide range of flow condition, 1.06 < Re < 514, in X-shaped micro-channels, the mixture performances of numerical simulation, flow visualization, and temperature distribution remain the same. At the same mass flow rate as the Reynolds number below 112.53, the biggest channel size had the slowest flow velocity and got the best mixing performance; as the Reynolds number above 112.53, the smaller the channel sizing, the lower the pressure drops and the faster velocity becomes. The transition form early from laminar flow, the unsteady flow is an advantage for mixing in the limited mixing area, therefore 0.7 mm got the best mixing performance. It is clear that the size of the channel plays an important role in the X-shaped micro-channels.

  18. Employment of neural networks for analysis of chemical composition and cooling rate effect on CCT diagrams shape

    International Nuclear Information System (INIS)

    Dobrzanski, L.A.; Trzaska, J.

    2004-01-01

    The paper presents possibility of employment of the original supercooled austenite transformation anisothermic diagrams forecasting method for analysis of the chemical composition effect on the CCT diagrams shape. The developed model makes it possible to substitute computer simulation for the costly and time consuming experiments. The information derived from calculations make it possible to plot diagrams illustrating the effects of the particular elements or pairs of elements, as well as cooling rate and/or austenitizing temperature, on any temperature or time describing transformations in steel during its continuous cooling. Evaluation is also possible of the effect of the aforementioned factors on hardness and fractions of the particular structural constituents. (author)

  19. Effects of particle's off-axis position, shape, orientation and entry position on resistance changes of micro Coulter counting devices

    International Nuclear Information System (INIS)

    Qin, Zhenpeng; Zhe, Jiang; Wang, Guo-Xiang

    2011-01-01

    With the recent advance in micro/nano-fabrication technology, micro Coulter counters have been widely used in detecting and characterizing micro- and nanoscale objects. In this paper, the electrical resistance change during translocation of a non-conducting particle through a channel is studied numerically. The numerical results are validated by proven analytical results available in the literature. The effects of particle's off-axis position, shape and orientation, and entry position are studied for particles with a large dynamic range. From the numerical results, a new fitted correlation is proposed that can accurately predict the resistance change caused by off-axis spherical particles regardless of their size. The shape and orientation effects of the electrical resistance change are studied by changing the axis ratio of spheroid particles and their orientation angles. Results show that a particle's shape and orientation have a significant influence on the resistance change. Simulation of an entry effect indicates that a particle starts to induce a resistance change before it enters the channel and still causes a resistance change even after the particle exits the channel completely. This study will offer some guidelines in designing and implementing Coulter counting devices and experiments, and provide insights into explaining experimental results

  20. Effects of heat treatment on microstructure and mechanical behaviour of additive manufactured porous Ti6Al4V

    NARCIS (Netherlands)

    Ahmadi, S.M.; Ashok Kumar Jain, R. K.; Zadpoor, A.A.; Ayas, C.; Popovich, V.

    2018-01-01

    Titanium and its alloys such as Ti6Al4V play a major role in the medical industry as bone implants. Nowadays, by the aid of additive manufacturing (AM), it is possible to manufacture porous complex structures which mimic human bone. However, AM parts are near net shape and post processing may be

  1. Plasma Fluctuation Studies in the TCV Tokamak: Modeling of Shaping Effects and Advanced Diagnostic Development

    International Nuclear Information System (INIS)

    Marinoni, A.

    2009-10-01

    therefore also well suited to investigate inhomogeneous spatial regions, where the need for an excellent spatial resolution is greatest. Additionally, it was also designed as translatable to broaden the region of study, which can extend up to the magnetic axis, in selected configurations. The translatable design combined with the flexibility of TCV in terms of plasma positioning in the vacuum vessel allows the phase contrast system to measure fluctuations across virtually the whole plasma minor radius. The diagnostic is sensitive both to radial and poloidal wave numbers, depending on the configuration. A parallel project to the development and installation of the phase contrast imaging system was the installation of a prototype Doppler reflectometer operating in a homodyne configuration, both in X and in O mode polarization. The reflectometer was operated parasitically to assess its performance which proved to be excellent; it is now routinely available on TCV. The theoretical part of the thesis consisted of extensive modeling of the effect of plasma shape, in particular triangularity, on turbulent transport by means of linear and nonlinear gyrokinetic simulations. This was motivated by experiments on TCV that had shown a dramatic improvement in confinement, up to a factor of two, in inverting the sign of the triangularity from positive to negative. Negative triangularity was indeed found to have a stabilizing influence on ion scale instabilities, specifically on the so called trapped electron mode (TEM). Simulations were carried out on actual TCV shots and the variation of the heat flux with triangularity calculated by the nonlinear simulations is in fair agreement with the experimental results. Linear simulations and a simple analytical model explain, in agreement with nonlinear runs, the resulting stabilization as a result of a rather complex modification of the toroidal precessional drift of trapped particles exerted by negative triangularity. (author)

  2. Enhanced magnetoelectric effects in composite of piezoelectric ceramics, rare-earth iron alloys, and shape-optimized nanocrystalline alloys.

    Science.gov (United States)

    Zhang, Jitao; Li, Ping; Wen, Yumei; He, Wei; Yang, Aichao; Lu, Caijiang

    2014-03-01

    An enhancement for magnetoelectric (ME) effects is studied in a three-phase ME architecture consisting of two magnetostrictive Terfenol-D (Tb(0.3)Dy(0.7)Fe(1.92)) plates, a piezoelectric PZT (Pb(Zr,Ti)O3) plate, and a pair of shape-optimized FeCuNbSiB nanocrystalline alloys. By modifying the conventional shape of the magnetic flux concentrator, the shape-optimized flux concentrator has an improved effective permeability (μ(eff)) due to the shape-induced demagnetizing effect at its end surface. The flux concentrator concentrates and amplifies the external magnetic flux into Terfenol-D plate by means of changing its internal flux concentrating manner. Consequently, more flux lines can be uniformly concentrated into Terfenol-D plates. The effective piezomagnetic coefficients (d(33m)) of Terfenol-D plate and the ME voltage coefficients (α(ME)) can be further improved under a lower magnetic bias field. The dynamic magneto-elastic properties and the effective magnetic induction of Terfenol-D are taken into account to derive the enhanced effective ME voltage coefficients (α(ME,eff)), the consistency of experimental results and theoretical analyses verifies this enhancement. The experimental results demonstrate that the maximum d(33m) in our proposed architecture achieves 22.48 nm/A under a bias of 114 Oe. The maximum α(ME) in the bias magnetic range 0-900 Oe reaches 84.73 mV/Oe under the low frequency of 1 kHz, and 2.996 V/Oe under the resonance frequency of 102.3 kHz, respectively. It exhibits a 1.43 times larger piezomagnetic coefficient and a 1.87 times higher ME voltage coefficient under a smaller magnetic bias of 82 Oe than those of a conventional Terfenol-D/PZT/Terfenol-D composite. These shape-induced magnetoelectric behaviors provide the possibility of using this ME architecture in ultra-sensitive magnetic sensors.

  3. A ‘frozen volume’ transition model and working mechanism for the shape memory effect in amorphous polymers

    Science.gov (United States)

    Lu, Haibao; Wang, Xiaodong; Yao, Yongtao; Qing Fu, Yong

    2018-06-01

    Phenomenological models based on frozen volume parameters could well predict shape recovery behavior of shape memory polymers (SMPs), but the physical meaning of using the frozen volume parameters to describe thermomechanical properties has not been well-established. In this study, the fundamental working mechanisms of the shape memory effect (SME) in amorphous SMPs, whose temperature-dependent viscoelastic behavior follows the Eyring equation, have been established with the considerations of both internal stress and its resulted frozen volume. The stress-strain constitutive relation was initially modeled to quantitatively describe effects of internal stresses at the macromolecular scale based on the transient network theory. A phenomenological ‘frozen volume’ model was then established to characterize the macromolecule structure and SME of amorphous SMPs based on a two-site stress-relaxation model. Effects of the internal stress, frozen volume and strain rate on shape memory behavior and thermomechanical properties of the SMP were investigated. Finally, the simulation results were compared with the experimental results reported in the literature, and good agreements between the theoretical and experimental results were achieved. The novelty and key differences of our newly proposed model with respect to the previous reports are (1). The ‘frozen volume’ in our study is caused by the internal stress and governed by the two-site model theory, thus has a good physical meaning. (2). The model can be applied to characterize and predict both the thermal and thermomechanical behaviors of SMPs based on the constitutive relationship with internal stress parameters. It is expected to provide a power tool to investigate the thermomechanical behavior of the SMPs, of which both the macromolecular structure characteristics and SME could be predicted using this ‘frozen volume’ model.

  4. Modeling fiber motion in a pulp pressure screen: the effect of slot shape

    International Nuclear Information System (INIS)

    Dong, S.; Salcudean, M.; Gartshore, I.

    2003-01-01

    A pressure screen is a piece of equipment in the pulp and paper industry used either to remove contaminants from the pulp suspension or to separate fibers having different properties. Contaminants such as fiber bundles, bark and plastic specks are introduced when fibers are separated from the wood by mechanical or chemical pulping processes. Contaminants significantly affect the strength and smoothness of the paper and must be removed before the final paper is produced. The screen plate is a critical part of the pressure screen and its design is the key to screen performance. This paper uses a new and comprehensive CFD simulation tool to examine the flow and fiber behavior in a single slot screen having any reasonable slot shape. -This simulation tool includes three coupled models: first, the flow model solves the Reynolds Averaged Navier-Stokes (RANS) equation using the standard k - ε turbulence model to predict the flow field in the equipment. Second, a three-dimensional flexible fiber model is used to track the fiber trajectory in the screen. Third, a very general wall model is used to deal with the case when a fiber touches the equipment wall. The simulated results show that the slot shape has a critical influence on fiber behavior and screen performance. Three general slot shapes were investigated: the smooth slot, the step-step contour slot and slope-slope contour slot. Of these the slope-slope contour slot provides the best passage for the fibers with a length of 1mm and 3mm. (author)

  5. Thin Cu film resistivity using four probe techniques: Effect of film thickness and geometrical shapes

    Science.gov (United States)

    Choudhary, Sumita; Narula, Rahul; Gangopadhyay, Subhashis

    2018-05-01

    Precise measurement of electrical sheet resistance and resistivity of metallic thin Cu films may play a significant role in temperature sensing by means of resistivity changes which can further act as a safety measure of various electronic devices during their operation. Four point probes resistivity measurement is a useful approach as it successfully excludes the contact resistance between the probes and film surface of the sample. Although, the resistivity of bulk samples at a particular temperature mostly depends on its materialistic property, however, it may significantly differ in the case of thin films, where the shape and thickness of the sample can significantly influence on it. Depending on the ratio of the film thickness to probe spacing, samples are usually classified in two segments such as (i) thick films or (ii) thin films. Accordingly, the geometric correction factors G can be related to the sample resistivity r, which has been calculated here for thin Cu films of thickness up to few 100 nm. In this study, various rectangular shapes of thin Cu films have been used to determine the shape induced geometric correction factors G. An expressions for G have been obtained as a function of film thickness t versus the probe spacing s. Using these expressions, the correction factors have been plotted separately for each cases as a function of (a) film thickness for fixed linear probe spacing and (b) probe distance from the edge of the film surface for particular thickness. Finally, we compare the experimental results of thin Cu films of various rectangular geometries with the theoretical reported results.

  6. The effect of texture unit shape on silicon surface on the absorption properties

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Xiao-She; Zhang, Yi-Jie; Wang, Hao-Wei [Institute of Ecological and Environmental Materials, School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-02-15

    Improving the utilization ratio of sunlight is a key factor for the development of solar cell. In this work, different structures including triangular pyramid, rectangular pyramid, hexangular pyramid and cone structure are established to investigate the influences of many factors, like geometrical shape, density and the top angle of the texture unit on silicon front surface to sunlight absorption. Ray-tracing technology is used for simulation. The simulation results indicate that the triangular pyramid texture on silicon front surface performs the best, and its total absorption rate is more than 90% for the light with wavelength between 640 and 1080 nm when the top angle of pyramid is less than 100 . (author)

  7. Experimental and numerical modeling of chloride diffusivity in hardened cement concrete considering the aggregate shapes and exposure-duration effects

    Directory of Open Access Journals (Sweden)

    Wu Jie

    Full Text Available This paper presents an experimental and numerical model describing the effects of the aggregate shapes and exposure duration of chloride diffusion into cement-based materials. A simple chloride diffusion test was performed on a concrete specimen composed of a mixture of cement mortar with crushed granites and round gravels. A simulation was done and the numerical model developed was applied to the matrix at the meso-scale level and the chloride diffusivity was investigated at 30, 60, and 90 days. The experimental and simulation results showed that the aggregate shape and the exposure duration of chloride diffusing into concrete are of high significance. It was indicated that the model with crushed granite presents a good resistance against chloride ingress, while the model with rounded gravels shows some sensitivity to the chloride penetration. It was also found out that when the time dependence of the diffusion coefficient is not taken into account, the diffusion rate will be overestimated. The meso-scale model developed in this study also provides a new method applied in the analysis of the chloride and water transport that causes damage to concrete considering the particle inclusion and the diffusion duration. Keywords: Meso-scale modeling, Chloride diffusivity, Concrete, Effects of aggregates shape and exposure duration, FEM

  8. INVESTIGATION ON THE EFFECT OF SHAPES ON THE DRYING KINETICS AND SENSORY EVALUATION STUDY OF DRIED JACKFRUIT

    Directory of Open Access Journals (Sweden)

    Pek Li Gan

    2014-10-01

    Full Text Available Jackfruits are seasonal and highly nutritional fruits indigenous to the Southwestern rainforests of India. However much of the produce are spoilt annually due to poor preservation techniques. Minimal studies have been conducted on the drying kinetics of jackfruit and the effect of shapes on the drying kinetics. In this research, drying curves of three different shaped jackfruit slices were obtained using a convective oven at 40oC, 50oC, 60oC and 70oC. Modified Midilli-Kucuk Model was found to be the best kinetic model for drying of jackfruits. At all temperatures, effective moisture diffusivity values and activation energy varied from 2.66 x 10-10 - 4.85 x 10-10 m2/s and 16.08 - 20.07 kJ/mol respectively. Drying was found to be most efficient at 50oC using the square shaped slices with a R2, RMSE and SSE value of 0.9984, 0.01127 and 0.002668 respectively.  Sensory evaluation of untreated and additive-added dried jackfruit slices was conducted by 40 untrained sensory panelists. Jackfruit with ascorbic acid and sugar coating had highest aesthetics value due to better retention of colour by ascorbic acid. However sugar coated jackfruit had the most favorable taste and smell. Further optimization must be done to satisfy consumers collectively to enable a highly marketable product.

  9. The effect of the melting spinning cooling rate on transformation temperatures in ribbons Ti-Ni-Cu shape memory

    International Nuclear Information System (INIS)

    Ramos, A.P.; Castro, W.B.; Anselmo, G.C. dos S.

    2014-01-01

    Ti-Ni-Cu alloys have been attracting attention by their high performance of shape memory effect and decrease of thermal and stress hysteresis in comparison with Ti-Ni binary alloys. One important challenge of microsystems design is the implementation of miniaturized actuation principles efficient at the micro-scale. Shape memory alloys (SMAs) have early on been considered as a potential solution to this problem as these materials offer attractive properties like a high-power to weight ratio, large deformation and the capability to be processed at the micro-scale. Shape memory characteristics of Ti-37,8Cu-18,7Ni alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change of the velocity of cooling wheel from 21 to 63 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on austenitic and martensitic transformations behaviors is discussed. (author)

  10. Effect of defects, magnetocrystalline anisotropy, and shape anisotropy on magnetic structure of iron thin films by magnetic force microscopy

    Directory of Open Access Journals (Sweden)

    Ke Xu

    2017-05-01

    Full Text Available Microstructures of magnetic materials, including defects and crystallographic orientations, are known to strongly influence magnetic domain structures. Measurement techniques such as magnetic force microscopy (MFM thus allow study of correlations between microstructural and magnetic properties. The present work probes effects of anisotropy and artificial defects on the evolution of domain structure with applied field. Single crystal iron thin films on MgO substrates were milled by Focused Ion Beam (FIB to create different magnetically isolated squares and rectangles in [110] crystallographic orientations, having their easy axis 45° from the sample edge. To investigate domain wall response on encountering non-magnetic defects, a 150 nm diameter hole was created in the center of some samples. By simultaneously varying crystal orientation and shape, both magnetocrystalline anisotropy and shape anisotropy, as well as their interaction, could be studied. Shape anisotropy was found to be important primarily for the longer edge of rectangular samples, which exaggerated the FIB edge effects and provided nucleation sites for spike domains in non-easy axis oriented samples. Center holes acted as pinning sites for domain walls until large applied magnetic fields. The present studies are aimed at deepening the understanding of the propagation of different types of domain walls in the presence of defects and different crystal orientations.

  11. Effects of anticaricaturing vs. caricaturing and their neural correlates elucidate a role of shape for face learning.

    Science.gov (United States)

    Schulz, Claudia; Kaufmann, Jürgen M; Walther, Lydia; Schweinberger, Stefan R

    2012-08-01

    To assess the role of shape information for unfamiliar face learning, we investigated effects of photorealistic spatial anticaricaturing and caricaturing on later face recognition. We assessed behavioural performance and event-related brain potential (ERP) correlates of recognition, using different images of anticaricatures, veridical faces, or caricatures at learning and test. Relative to veridical faces, recognition performance improved for caricatures, with performance decrements for anticaricatures in response times. During learning, an amplitude pattern with caricatures>veridicals=anticaricatures was seen for N170, left-hemispheric ERP negativity during the P200 and N250 time segments (200-380 ms), and for a late positive component (LPC, 430-830 ms), whereas P200 and N250 responses exhibited an additional difference between veridicals and anticaricatures over the right hemisphere. During recognition, larger amplitudes for caricatures again started in the N170, whereas the P200 and the right-hemispheric N250 exhibited a more graded pattern of amplitude effects (caricatures>veridicals>anticaricatures), a result which was specific to learned but not novel faces in the N250. Together, the results (i) emphasise the role of facial shape for visual encoding in the learning of previously unfamiliar faces and (ii) provide important information about the neuronal timing of the encoding advantage enjoyed by faces with distinctive shape. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Hydrostatic pressure and temperature effects on nonlinear optical rectification in a lens shape InAs/GaAs quantum dot

    International Nuclear Information System (INIS)

    Bouzaïene, L.; Ben Mahrsia, R.; Baira, M.; Sfaxi, L.; Maaref, H.

    2013-01-01

    We have performed theoretical calculation of the nonlinear optical rectification in a lens shape InAs/GaAs quantum dot (0D). The combined effects of hydrostatic pressure and temperature on the nonlinear optical rectification in lens-shaped InAs QDs are studied under the compact density matrix formalism and the effective mass approximation. From our calculation, it is found that the subband energies and optical rectification susceptibility are quite sensitive to the applied hydrostatic pressure and temperature. The results show that the resonant peak of the optical rectification can be red-shifted or blue-shifted and their intensity also varied by external probes such as hydrostatic pressure and temperature. In addition, the oscillator strength is strongly affected by these parameters. - Highlights: ► Theoretical calculation of the nonlinear optical rectification in a lens shape InAs/GaAs quantum dot was performed. ► Optical rectification susceptibility is quite sensitive to the applied hydrostatic pressure and temperature. ► The oscillator strength is strongly affected by the applied hydrostatic pressure and temperature.

  13. Sn buffered by shape memory effect of NiTi alloys as high-performance anodes for lithium ion batteries

    International Nuclear Information System (INIS)

    Hu Renzong; Zhu Min; Wang Hui; Liu Jiangwen; Liuzhang Ouyang; Zou Jin

    2012-01-01

    By applying the shape memory effect of the NiTi alloys to buffer the Sn anodes, we demonstrate a simple approach to overcome a long-standing challenge of Sn anode in the applications of Li-ion batteries – the capacity decay. By supporting the Sn anodes with NiTi shape memory alloys, the large volume change of Sn anodes due to lithiation and delithiation can be effectively accommodated, based on the stress-induced martensitic transformation and superelastic recovery of the NiTi matrix respectively, which leads to a decrease in the internal stress and closing of cracks in Sn anodes. Accordingly, stable cycleability (630 mA h g −1 after 100 cycles at 0.7C) and excellent high-rate capabilities (478 mA h g −1 at 6.7C) were attained with the NiTi/Sn/NiTi film electrode. These shape memory alloys can also combine with other high-capacity metallic anodes, such as Si, Sb, Al, and improve their cycle performance.

  14. Effect of Cylinder Liner Oil Grooves Shape on Two-Stroke Marine Diesel Engine's Piston Ring Friction Force

    Directory of Open Access Journals (Sweden)

    Salaheldin A. Mohamad

    2015-02-01

    Full Text Available The dimensions, area densities, and geometry of macroscale surface textures may affect the performance of hydrodynamic lubrication interface. Reported in this paper are the investigations of the effect of surface textures bottom shapes on the friction forces between piston ring and cylinder liner for two-stroke marine diesel engine, using numerically generated textures and average Reynolds equation. These textures are on the cylinder liner surface in the form of circumferential oil grooves with different aspect ratios and different area densities. The hydrodynamic pressure distribution is also calculated using Reynolds boundary condition. The results revealed that the bottom shape could positively affect the friction between moving surfaces, as it could provide a microwedge or microstep bearing that tends to enhance the lubrication condition between piston ring and cylinder liner.

  15. Effect of voltage shape of electrical power supply on radiation and density of a cold atmospheric argon plasma jet

    Directory of Open Access Journals (Sweden)

    F Sohbatzadeh

    2017-02-01

    Full Text Available In this work, we investigated generating argon cold plasma jet at atmospheric pressure based on dielectric barrier discharge configuration using three electrical power supplies of sinusoidal, pulsed and saw tooth high voltage shapes at 8 KHZ. At first; we describe the electronic circuit features for generating high voltage (HV wave forms including saw tooth, sinusoidal and pulsed forms. Then, we consider the effect of voltage shape on the electrical breakdown. Relative concentrations of chemical reactive species such as Oxygen, atomic Nitrogen and OH were measured using optical emission spectroscopy. Using a simple numerical model, we showed a HV with less rise time increases electron density, therefore a cold plasma jet can be produced with a minimal consumption electrical power

  16. Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

    Directory of Open Access Journals (Sweden)

    Chetan Aneja

    2016-07-01

    Full Text Available In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases with decreasing welding speed. Furthermore mechanical properties were also found to improve as the rotary speed increases and the same phenomenon was found to happen while using straight cylindrical threaded pin profile tool. The microstructure of the dissimilar joints revealed that at low welding speeds, the improved material mixing was observed. The similar phenomenon was found to happen at higher rotational speeds using straight cylindrical threaded tool.

  17. Shape isomerism and shape coexistence effects on the Coulomb energy differences in the N=Z nucleus 66As and neighboring T=1 multiplets

    Science.gov (United States)

    de Angelis, G.; Wiedemann, K. T.; Martinez, T.; Orlandi, R.; Petrovici, A.; Sahin, E.; Valiente-Dobón, J. J.; Tonev, D.; Lunardi, S.; Nara Singh, B. S.; Wadsworth, R.; Gadea, A.; Kaneko, K.; Bizzeti, P. G.; Bizzeti-Sona, A. M.; Blank, B.; Bracco, A.; Carpenter, M. P.; Chiara, C. J.; Farnea, E.; Gottardo, A.; Greene, J. P.; Lenzi, S. M.; Leoni, S.; Lister, C. J.; Mengoni, D.; Napoli, D. R.; Pechenaya, O. L.; Recchia, F.; Reviol, W.; Sarantites, D. G.; Seweryniak, D.; Ur, C. A.; Zhu, S.

    2012-03-01

    Excited states of the N=Z=33 nucleus 66As have been populated in a fusion-evaporation reaction and studied using γ-ray spectroscopic techniques. Special emphasis was put into the search for candidates for the T=1 states. A new 3+ isomer has been observed with a lifetime of 1.1(3) ns. This is believed to be the predicted oblate shape isomer. The excited levels are discussed in terms of the shell model and of the complex excited Vampir approaches. Coulomb energy differences are determined from the comparison of the T=1 states with their analog partners. The unusual behavior of the Coulomb energy differences in the A=70 mass region is explained through different shape components (oblate and prolate) within the members of the same isospin multiplets. This breaking of the isospin symmetry is attributed to the correlations induced by the Coulomb interaction.

  18. Coupled spin and shape evolution of small rubble-pile asteroids and self-limitation of the YORP effect

    Science.gov (United States)

    Cotto-Figueroa, D.; Statler, T.; Richardson, D.; Tanga, P.

    2014-07-01

    We present the results of the first simulations that self-consistently model the YORP effect on the spin states of dynamically evolving aggregates. Extensive analyses of the basic behavior of the YORP effect have been previously conducted leading to the idea of the classical ''YORP cycle''. These studies are based on the assumption that the objects are rigid bodies, but evidence from lightcurve observations strongly suggests that most asteroids are aggregates. The timescales over which mass reconfiguration occur are much shorter than the timescales over which YORP changes the spin states and Statler [2009] has shown that the YORP effect has an extreme sensitivity to the topography of the asteroids (Icarus 202, 501--513). As the YORP effect changes the spin, the change in spin results in a change of the shape, which subsequently changes the YORP torques. The continuous changes in the shape of an aggregate result in a different evolution of the YORP torques and therefore aggregates do not evolve through the YORP cycle as a rigid body would. Instead of having a spin evolution ruled by long periods of rotational acceleration and deceleration as predicted by the YORP cycle, the YORP effect is self-limiting on aggregate asteroids exhibiting a stochastic behavior and/or a self-governed behavior. We provide a description of the stochastic and self-governed behaviors of the YORP effect along with the results of shape evolution including the types, magnitudes, and frequencies of movement and shedding of material. Although rotational acceleration for long periods of time is not achieved, a fraction of objects do present mass-shedding episodes at lower spin rates than the critical spin limit for aggregate asteroids. We also provide the bulk properties of the obtained distribution of changes in the spin rates, which are necessary in order to model correctly the coupled Yarkovsky/YORP evolution.

  19. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    Science.gov (United States)

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes. © 2015 Institute of Food Technologists®

  20. The effect of laser pulse shape variations on the adiabat of NIF capsule implosions

    Energy Technology Data Exchange (ETDEWEB)

    Robey, H. F.; MacGowan, B. J.; Landen, O. L.; LaFortune, K. N.; Widmayer, C.; Celliers, P. M.; Moody, J. D.; Ross, J. S.; Ralph, J.; LePape, S.; Berzak Hopkins, L. F.; Spears, B. K.; Haan, S. W.; Clark, D.; Lindl, J. D.; Edwards, M. J. [LLNL, Livermore, California 94550 (United States)

    2013-05-15

    Indirectly driven capsule implosions on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are being performed with the goal of compressing a layer of cryogenic deuterium-tritium (DT) fuel to a sufficiently high areal density (ρR) to sustain the self-propagating burn wave that is required for fusion power gain greater than unity. These implosions are driven with a temporally shaped laser pulse that is carefully tailored to keep the DT fuel on a low adiabat (ratio of fuel pressure to the Fermi degenerate pressure). In this report, the impact of variations in the laser pulse shape (both intentionally and unintentionally imposed) on the in-flight implosion adiabat is examined by comparing the measured shot-to-shot variations in ρR from a large ensemble of DT-layered ignition target implosions on NIF spanning a two-year period. A strong sensitivity to variations in the early-time, low-power foot of the laser pulse is observed. It is shown that very small deviations (∼0.1% of the total pulse energy) in the first 2 ns of the laser pulse can decrease the measured ρR by 50%.

  1. Masking Period Patterns & Forward Masking for Speech-Shaped Noise: Age-related effects

    Science.gov (United States)

    Grose, John H.; Menezes, Denise C.; Porter, Heather L.; Griz, Silvana

    2015-01-01

    Objective The purpose of this study was to assess age-related changes in temporal resolution in listeners with relatively normal audiograms. The hypothesis was that increased susceptibility to non-simultaneous masking contributes to the hearing difficulties experienced by older listeners in complex fluctuating backgrounds. Design Participants included younger (n = 11), middle-aged (n = 12), and older (n = 11) listeners with relatively normal audiograms. The first phase of the study measured masking period patterns for speech-shaped noise maskers and signals. From these data, temporal window shapes were derived. The second phase measured forward-masking functions, and assessed how well the temporal window fits accounted for these data. Results The masking period patterns demonstrated increased susceptibility to backward masking in the older listeners, compatible with a more symmetric temporal window in this group. The forward-masking functions exhibited an age-related decline in recovery to baseline thresholds, and there was also an increase in the variability of the temporal window fits to these data. Conclusions This study demonstrated an age-related increase in susceptibility to non-simultaneous masking, supporting the hypothesis that exacerbated non-simultaneous masking contributes to age-related difficulties understanding speech in fluctuating noise. Further support for this hypothesis comes from limited speech-in-noise data suggesting an association between susceptibility to forward masking and speech understanding in modulated noise. PMID:26230495

  2. Masking Period Patterns and Forward Masking for Speech-Shaped Noise: Age-Related Effects.

    Science.gov (United States)

    Grose, John H; Menezes, Denise C; Porter, Heather L; Griz, Silvana

    2016-01-01

    The purpose of this study was to assess age-related changes in temporal resolution in listeners with relatively normal audiograms. The hypothesis was that increased susceptibility to nonsimultaneous masking contributes to the hearing difficulties experienced by older listeners in complex fluctuating backgrounds. Participants included younger (n = 11), middle-age (n = 12), and older (n = 11) listeners with relatively normal audiograms. The first phase of the study measured masking period patterns for speech-shaped noise maskers and signals. From these data, temporal window shapes were derived. The second phase measured forward-masking functions and assessed how well the temporal window fits accounted for these data. The masking period patterns demonstrated increased susceptibility to backward masking in the older listeners, compatible with a more symmetric temporal window in this group. The forward-masking functions exhibited an age-related decline in recovery to baseline thresholds, and there was also an increase in the variability of the temporal window fits to these data. This study demonstrated an age-related increase in susceptibility to nonsimultaneous masking, supporting the hypothesis that exacerbated nonsimultaneous masking contributes to age-related difficulties understanding speech in fluctuating noise. Further support for this hypothesis comes from limited speech-in-noise data, suggesting an association between susceptibility to forward masking and speech understanding in modulated noise.

  3. Memory updating in sub-clinical eating disorder: differential effects with food and body shape words.

    Science.gov (United States)

    Fenton, Olivia; Ecker, Ullrich K H

    2015-04-01

    The present study investigated how eating disorder (ED) relevant information is updated in working memory in people with high vs. low scores on a measure of eating disorder pathology (the Eating Disorder Examination Questionnaire, EDE-Q). Participants performed two memory updating tasks. One was a neutral control task using digits; the other task involved food words and words relating to body-shape, and provided measures of updating speed and post-updating recall. We found that high EDE-Q participants (1) showed no sign of general memory updating impairment as indicated by performance in the control task; (2) showed a general recall deficit in the task involving ED-relevant stimuli, suggesting a general distraction of cognitive resources in the presence of ED-related items; (3) showed a relative facilitation in the recall of food words; and (4) showed quicker updating toward food words and relatively slower updating toward body-shape-related words. Results are discussed in the context of cognitive theories of eating disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Effects of anisotropy on the equilibrium shape of nanoscale pores at grain boundaries

    International Nuclear Information System (INIS)

    Wynblatt, Paul; Chatain, Dominique

    2013-01-01

    Molecular dynamics simulations have been performed to study the interaction between a faceted pore and an anisotropic grain boundary (GB). Nickel was chosen as a convenient model system. In order to establish the equilibrium crystal shape (ECS) of the pore, studies were also conducted on isolated pores. Isolated pores were found to be subject to the nucleation inhibition of equilibration that has been predicted by Rohrer et al. (J Am Ceram Soc 2000;83:214, 2001;84: 2099). This work shows that configurations close to the ECS can be obtained if supersaturation within a pore is artificially increased by adding mobile adatoms to the internal surfaces of the pores. In the case of pores located at GBs, the nucleation energy barriers to facet displacement are not present for facets in contact with the GB at the triple line, but may still persist for facets that have no contact with the GB. This problem can be overcome by approaching the equilibrium shape from different initial configurations. The configuration of the GB in the vicinity of the pore has been found to be essentially planar, indicating that GB puckering in the vicinity of anisotropic pores is not generally necessary. The present calculations show that incompatibilities between misoriented pore facets that meet at the triple line with the GB are easily accommodated by local atomic rearrangements at the disordered region of intersection with the GB

  5. Effect of island shape on dielectrophoretic assembly of metal nanoparticle chains in a conductive-island-based microelectrode system

    International Nuclear Information System (INIS)

    Ding, Haitao; Shao, Jinyou; Ding, Yucheng; Liu, Weiyu; Li, Xiangming; Tian, Hongmiao; Zhou, Yaopei

    2015-01-01

    Highlights: • Conductive island shape influences the dynamic process occurring in DEP assembly of 10 nm gold nanoparticles in a conductive-island-based microelectrode system. • The DEP-assembled nanoparticle wires form a straighter conduction path with the increase in the geometric angle of conductive island tip. • The different island shapes distort the DEP force distribution and increase the local electrothermally induced fluid flow to different extents, which is important for the morphology and electrical conductance quality of the DEP-assembled metal nanoparticle chains. - Abstract: The electrical conduction quality of an electric circuit connection formed by dielectrophoretic (DEP)-assembled metal nanoparticle wires between small conductive elements plays a significant role in electronic devices. One of the major challenges for improving the electrical conductance of nanowires is optimizing their geometric morphology. So far, the electrical conduction quality has been enhanced by optimizing the AC frequency and conductivity of nanoparticle suspensions. Herein, the effect of the conductive island shapes on the dynamic process occurring in a DEP assembly of 10 nm gold nanoparticles was investigated in a conductive-island-based microelectrode system. The nanoparticle wires between the microelectrodes were assembled in situ from colloidal suspensions. The wires were grown in a much straighter route by increasing the geometric angle of the conductive-island tip. To validate the experiments, the effects of mutual DEP interactions and electrothermally induced fluid flow on the dynamic behavior of particle motion for different island geometric configurations in the conductive-island-based microelectrode system were determined by numerical simulations. The simulation results are consistent with those of experiments. This indicates that different conductive island shapes change the distribution of DEP force and increase the electrothermally induced fluid flow to

  6. Effect of Ta Additions on the Microstructure, Damping, and Shape Memory Behaviour of Prealloyed Cu-Al-Ni Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Safaa N. Saud

    2017-01-01

    Full Text Available The influence of Ta additions on the microstructure and properties of Cu-Al-Ni shape memory alloys was investigated in this paper. The addition of Ta significantly affects the green and porosity densities; the minimum percentage of porosity was observed with the modified prealloyed Cu-Al-Ni-2.0 wt.% Ta. The phase transformation temperatures were shifted towards the highest values after Ta was added. Based on the damping capacity results, the alloy of Cu-Al-Ni-3.0 wt.% Ta has very high internal friction with the maximum equivalent internal friction value twice as high as that of the prealloyed Cu-Al-Ni SMA. Moreover, the prealloyed Cu-Al-Ni SMAs with the addition of 2.0 wt.% Ta exhibited the highest shape recovery ratio in the first cycle (i.e., 100% recovery, and when the number of cycles is increased, this ratio tends to decrease. On the other hand, the modified alloys with 1.0 and 3.0 wt.% Ta implied a linear increment in the shape recovery ratio with increasing number of cycles. Polarization tests in NaCl solution showed that the corrosion resistance of Cu-Al-Ni-Ta SMA improved with escalating Ta concentration as shown by lower corrosion current densities, higher corrosion potential, and formation of stable passive film.

  7. Effect of Ta Additions on the Microstructure, Damping, and Shape Memory Behaviour of Prealloyed Cu-Al-Ni Shape Memory Alloys.

    Science.gov (United States)

    Saud, Safaa N; Hamzah, E; Bakhsheshi-Rad, H R; Abubakar, T

    2017-01-01

    The influence of Ta additions on the microstructure and properties of Cu-Al-Ni shape memory alloys was investigated in this paper. The addition of Ta significantly affects the green and porosity densities; the minimum percentage of porosity was observed with the modified prealloyed Cu-Al-Ni-2.0 wt.% Ta. The phase transformation temperatures were shifted towards the highest values after Ta was added. Based on the damping capacity results, the alloy of Cu-Al-Ni-3.0 wt.% Ta has very high internal friction with the maximum equivalent internal friction value twice as high as that of the prealloyed Cu-Al-Ni SMA. Moreover, the prealloyed Cu-Al-Ni SMAs with the addition of 2.0 wt.% Ta exhibited the highest shape recovery ratio in the first cycle (i.e., 100% recovery), and when the number of cycles is increased, this ratio tends to decrease. On the other hand, the modified alloys with 1.0 and 3.0 wt.% Ta implied a linear increment in the shape recovery ratio with increasing number of cycles. Polarization tests in NaCl solution showed that the corrosion resistance of Cu-Al-Ni-Ta SMA improved with escalating Ta concentration as shown by lower corrosion current densities, higher corrosion potential, and formation of stable passive film.

  8. Numerical Investigation of the Effect of Magnetic Field on Natural Convection in a Curved-Shape Enclosure

    Directory of Open Access Journals (Sweden)

    M. Sheikholeslami

    2013-01-01

    Full Text Available This investigation reports the magnetic field effect on natural convection heat transfer in a curved-shape enclosure. The numerical investigation is carried out using the control volume-based-finite element method (CVFEM. The numerical investigations are performed for various values of Hartmann number and Rayleigh number. The obtained results are depicted in terms of streamlines and isotherms which show the significant effects of Hartmann number on the fluid flow and temperature distribution inside the enclosure. Also, it was found that the Nusselt number decreases with an increase in the Hartmann number.

  9. Effect of duct shape, Mach number, and lining construction on measured suppressor attenuation and comparison with theory

    Science.gov (United States)

    Olsen, W. A.; Krejsa, E. A.; Coats, J. W.

    1972-01-01

    Noise attenuation was measured for several types of cylindrical suppressors that use a duct lining composed of honeycomb cells covered with a perforated plate. The experimental technique used gave attenuation data that were repeatable and free of noise floors and other sources of error. The suppressor length, the effective acoustic diameter, suppressor shape and flow velocity were varied. The agreement among the attenuation data and two widely used analytical models was generally satisfactory. Changes were also made in the construction of the acoustic lining to measure their effect on attenuation. One of these produced a very broadband muffler.

  10. Shape Memory Micro- and Nanowire Libraries for the High-Throughput Investigation of Scaling Effects.

    Science.gov (United States)

    Oellers, Tobias; König, Dennis; Kostka, Aleksander; Xie, Shenqie; Brugger, Jürgen; Ludwig, Alfred

    2017-09-11

    The scaling behavior of Ti-Ni-Cu shape memory thin-film micro- and nanowires of different geometry is investigated with respect to its influence on the martensitic transformation properties. Two processes for the high-throughput fabrication of Ti-Ni-Cu micro- to nanoscale thin film wire libraries and the subsequent investigation of the transformation properties are reported. The libraries are fabricated with compositional and geometrical (wire width) variations to investigate the influence of these parameters on the transformation properties. Interesting behaviors were observed: Phase transformation temperatures change in the range from 1 to 72 °C (austenite finish, (A f ), 13 to 66 °C (martensite start, M s ) and the thermal hysteresis from -3.5 to 20 K. It is shown that a vanishing hysteresis can be achieved for special combinations of sample geometry and composition.

  11. Effects of self-similar correlations on the spectral line shape in the neutral gas

    International Nuclear Information System (INIS)

    Kharintsev, S.S.; Salakhov, M.Kh.

    2001-01-01

    The paper is devoted to the study of the influence of self-similar correlations on the Doppler and pressure broadening within the non-equilibrium Boltzmann gas. The diffuse model for the thermal motion of the radiator and the self-similar mechanism of interference of scalar perturbations for phase shifts of an atomic oscillator are developed. It is shown that taking into account self-similar correlation in a description of the spectral line shape allows one to explain, on the one hand, the additional spectral line Dicke-narrowing in the Doppler regime, and, on the other hand, the asymmetry in wings of the spectral line in a high pressure region

  12. Effects of monomer shape on the formation of aggregates from a power law monomer distribution

    International Nuclear Information System (INIS)

    Perry, J; Kimery, J; Matthews, L S; Hyde, T W

    2013-01-01

    The coagulation of dust aggregates is an important process in many physical systems such as the Earth's upper atmosphere, comet tails and protoplanetary discs. Numerical models which study the aggregation in these systems typically involve spherical monomers. There is evidence, however, via the polarization of sunlight in the interstellar medium, as well as optical and LIDAR observations of high-altitude particles in Earth's atmosphere (70–100 km), which indicate that dust monomers may not necessarily be spherical. This study investigates the influence of different ellipsoidal monomer shapes on the morphology of aggregates given various distributions of monomer sizes. Populations of aggregates are grown from a single monomer using a combination of ballistic particle–cluster aggregation and ballistic cluster–cluster aggregation regimes incorporating the rotation of monomers and aggregates. The resulting structures of the aggregates are then compared via the compactness factor, geometric cross-section and friction time. (paper)

  13. Raman study of pressure effects on frequencies and isotropic line shapes in liquid acetone

    International Nuclear Information System (INIS)

    Schindler, W.; Sharko, P.T.; Jonas, J.

    1982-01-01

    The Raman line shape of the symmetric C = O stretching band at 1710 cm -1 has been measured in liquid acetone as a function of pressure from 1 bar to 4 kbar over the temperature range from -25 to 50 0 C. The experimental data obtained show several unusual features. First, there is a frequency difference of about 7 cm -1 between the polarized and depolarized components. Sceond, the isotropic linewidth GAMMA/sub iso/ decreases with increasing density, in contrast to the opposite trend usually found in other liquids. Third, the second moment M 2 (V) of the isotropic band appears to decrease with increasing density. The consideration of the experimental linewidth and frequency data leads to a conclusion that intermolecular dipole--dipole coupling between polar acetone molecules are responsible for the observed unusual behavior of , GAMMA/sub iso/, and M 2

  14. The effect of shape anisotropy in giant magnetostrictive fiber Bragg grating sensors

    International Nuclear Information System (INIS)

    Pacheco, C J; Bruno, A C

    2010-01-01

    We study the role of shape anisotropy on the strain response of magnetic field sensors based on square cuboids with giant magnetostriction and fiber Bragg gratings. We measured a maximum sensitivity of 18 µε mT −1 when a biasing uniform field of 15 mT was applied to a Tb 0.3 Dy 0.7 Fe 1.92 cuboid with an aspect ratio of 5.0. When gradient fields were applied, we were able to measure a significant change in the magnetostrictive response at different positions, attaching fiber Bragg gratings along the cuboid face containing the main magnetostrictive axis. Depending on the magnitude of the applied gradient, the magnetostrictive response was reduced by up to 34%

  15. Particle Shape Effect on Macroscopic Behaviour of Underground Structures: Numerical and Experimental Study

    Directory of Open Access Journals (Sweden)

    Szarf Krzysztof

    2015-02-01

    Full Text Available The mechanical performance of underground flexible structures such as buried pipes or culverts made of plastics depend not only on the properties of the structure, but also on the material surrounding it. Flexible drains can deflect by 30% with the joints staying tight, or even invert. Large deformations of the structure are difficult to model in the framework of Finite Element Method, but straightforward in Discrete Element Methods. Moreover, Discrete Element approach is able to provide information about the grain-grain and grain-structure interactions at the microscale. This paper presents numerical and experimental investigations of flexible buried pipe behaviour with focus placed on load transfer above the buried structure. Numerical modeling was able to reproduce the experimental results. Load repartition was observed, being affected by a number of factors such as particle shape, pipe friction and pipe stiffness.

  16. Numerical Study of the Plasticity-Induced Stabilization Effect on Martensitic Transformations in Shape Memory Alloys

    Science.gov (United States)

    Junker, Philipp; Hempel, Philipp

    2017-12-01

    It is well known that plastic deformations in shape memory alloys stabilize the martensitic phase. Furthermore, the knowledge concerning the plastic state is crucial for a reliable sustainability analysis of construction parts. Numerical simulations serve as a tool for the realistic investigation of the complex interactions between phase transformations and plastic deformations. To account also for irreversible deformations, we expand an energy-based material model by including a non-linear isotropic hardening plasticity model. An implementation of this material model into commercial finite element programs, e.g., Abaqus, offers the opportunity to analyze entire structural components at low costs and fast computation times. Along with the theoretical derivation and expansion of the model, several simulation results for various boundary value problems are presented and interpreted for improved construction designing.

  17. Synergistic effect of iron and intumescent flame retardant on shape-stabilized phase change material

    International Nuclear Information System (INIS)

    Zhang Ping; Hu Yuan; Song Lei; Lu Hongdian; Wang Jian; Liu Qingqing

    2009-01-01

    This paper deals with the preparation of paraffin/high density polyethylene (HDPE)/intumescent flame retardant (IFR)/iron as flame retardant shape-stabilized phase change material (FSPCM). The influences of iron for FSPCM on morphology, flammability property, latent heat and thermal conductive property were characterized by scanning electron microscopy (SEM), cone calorimeter, differential scanning calorimetry (DSC) and hot disk thermal constants analyser. It was found that iron could be well dispersed into the composite formed by HDPE and paraffin; the flame retardant efficiency of IFR could be improved by adding iron; the thermal conductivity of FSPCM could be increased due to the high thermal conductivity of iron. At the same time, the possible flame retardant mechanism for paraffin/HDPE/IFR with iron as a FSPCM was proposed

  18. Prediction of effects of punch shapes on tableting failure by using a multi-functional single-punch tablet press

    Directory of Open Access Journals (Sweden)

    Takashi Osamura

    2017-09-01

    Full Text Available We previously determined “Tableting properties” by using a multi-functional single-punch tablet press (GTP-1. We proposed plotting “Compactability” on the x-axis against “Manufacturability” on the y-axis to allow visual evaluation of “Tableting properties”. Various types of tableting failure occur in commercial drug production and are influenced by the amount of lubricant used and the shape of the punch. We used the GTP-1 to measure “Tableting properties” with different amounts of lubricant and compared the results with those of tableting on a commercial rotary tableting machine. Tablets compressed with a small amount of lubricant showed bad “Manufacturability”, leading to sticking of powder on punches. We also tested various punch shapes. The GTP-1 correctly predicted the actual tableting results for all punch shapes. With punches that were more likely to cause tableting failure, our system predicted the effects of lubricant quantity in the tablet formulation and the occurrence of sticking in the rotary tableting machine.

  19. Numerical investigation of shape domain effect to its elasticity and surface energy using adaptive finite element method

    Science.gov (United States)

    Alfat, Sayahdin; Kimura, Masato; Firihu, Muhammad Zamrun; Rahmat

    2018-05-01

    In engineering area, investigation of shape effect in elastic materials was very important. It can lead changing elasticity and surface energy, and also increase of crack propagation in the material. A two-dimensional mathematical model was developed to investigation of elasticity and surface energy in elastic material by Adaptive Finite Element Method. Besides that, behavior of crack propagation has observed for every those materials. The government equations were based on a phase field approach in crack propagation model that developed by Takaishi-Kimura. This research has varied four shape domains where physical properties of materials were same (Young's modulus E = 70 GPa and Poisson's ratio ν = 0.334). Investigation assumptions were; (1) homogeneous and isotropic material, (2) there was not initial cracking at t = 0, (3) initial displacement was zero [u1, u2] = 0) at initial condition (t = 0), and (4) length of time simulation t = 5 with interval Δt = 0.005. Mode I/II or mixed mode crack propagation has been used for the numerical investigation. Results of this studies were very good and accurate to show changing energy and behavior of crack propagation. In the future time, this research can be developed to complex phenomena and domain. Furthermore, shape optimization can be investigation by the model.

  20. Synergistic effect of shape-selective silver nanostructures decorating reduced graphene oxide nanoplatelets for enhanced cytotoxicity against breast cancer

    Science.gov (United States)

    Derakhshi, Maryam; Ashkarran, Ali Akbar; Bahari, Ali; Bonakdar, Shahin

    2018-07-01

    Graphene-based nanomaterials contain unique physicochemical properties and have been widely investigated due to a variety of applications particularly in cancer therapy. Furthermore, Ag has been known for its extensive historical background for biomedical applications. Therefore, conjugation of shape-selective Ag nanostructures with graphene may provide new horizons for pharmaceutical applications such as cancer treatments. Here we report on the synthesis of Ag nanoparticles (NPs)/reduced graphene oxide (AgNPs/RGO) conjugate nanomaterials containing various shapes of AgNPs by a novel and simple synthesis route using the deformation of dimethylformamide (DMF) as the reducing and coupling agent. The cytotoxicity and anticancer properties of AgNPs, AgNPs/RGO conjugate nanomaterials, RGO and graphene oxide (GO) were probed against MDA-MB-231 cancer and MCF-10A normal human breast cells in vitro. The AgNPs/RGO nanocomposites exhibited a strong anticancer effect by penetration and apoptosis in cancer cells as well as the lowest influence on the viability of normal cells. It was found that cancer cell viability not only depends on the geometry of Ag nanostructures but also on the interaction between AgNPs and RGO nanoplatelets. It is suggested that AgNPs/RGO conjugate nanomaterials with various shapes of AgNPs is a promising therapeutic platform for cancer therapy.

  1. Implementing and Quantifying the Shape-Memory Effect of Single Polymeric Micro/Nanowires with an Atomic Force Microscope.

    Science.gov (United States)

    Fang, Liang; Gould, Oliver E C; Lysyakova, Liudmila; Jiang, Yi; Sauter, Tilman; Frank, Oliver; Becker, Tino; Schossig, Michael; Kratz, Karl; Lendlein, Andreas

    2018-04-23

    The implementation of shape-memory effects (SME) in polymeric micro- or nano-objects currently relies on the application of indirect macroscopic manipulation techniques, for example, stretchable molds or phantoms, to ensembles of small objects. Here, we introduce a method capable of the controlled manipulation and SME quantification of individual micro- and nano-objects in analogy to macroscopic thermomechanical test procedures. An atomic force microscope was utilized to address individual electro-spun poly(ether urethane) (PEU) micro- or nanowires freely suspended between two micropillars on a micro-structured silicon substrate. In this way, programming strains of 10±1% or 21±1% were realized, which could be successfully fixed. An almost complete restoration of the original free-suspended shape during heating confirmed the excellent shape-memory performance of the PEU wires. Apparent recovery stresses of σ max,app =1.2±0.1 and 33.3±0.1 MPa were obtained for a single microwire and nanowire, respectively. The universal AFM test platform described here enables the implementation and quantification of a thermomechanically induced function for individual polymeric micro- and nanosystems. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effect of thermal cycling on the transformation temperature ranges of a Ni-Ti shape memory alloy

    International Nuclear Information System (INIS)

    Paula, A.S.; Canejo, J.P.H.G.; Martins, R.M.S.; Braz Fernandes, F.M.

    2003-01-01

    Shape memory alloys (SMA) represents a class of metallic materials that has the capability of recovering a previously defined initial shape when subject to an adequate thermomechanical treatment. The present work aims to study the influence of thermal cycles on the transition temperatures of a Ni-Ti alloy. In this system, small variations around the equiatomic composition give rise to significant transformation temperature variations ranging from 173 to 373 K. SMA usually presents the shape memory effect after an annealing treatment at ca. 973 K. The optimisation of the thermomechanical treatment will allow to 'tune' the material to different transformation temperature ranges from the same starting material, just by changing the processing conditions. Differential scanning calorimeter (DSC) and in situ high-temperature X-ray diffraction (XRD) have been used to identify the transformation temperatures and the phases that are present after different thermal cycles. The results concerning a series of thermal cycles with different heating and cooling rates (from 1.67x10 -2 to 1.25x10 -1 K/s) and different holding temperatures (from 473 to 1033 K) are presented

  3. Total peak shape analysis: detection and quantitation of concurrent fronting, tailing, and their effect on asymmetry measurements.

    Science.gov (United States)

    Wahab, M Farooq; Patel, Darshan C; Armstrong, Daniel W

    2017-08-04

    Most peak shapes obtained in separation science depart from linearity for various reasons such as thermodynamic, kinetic, or flow based effects. An indication of the nature of asymmetry often helps in problem solving e.g. in column overloading, slurry packing, buffer mismatch, and extra-column band broadening. However, existing tests for symmetry/asymmetry only indicate the skewness in excess (tail or front) and not the presence of both. Two simple graphical approaches are presented to analyze peak shapes typically observed in gas, liquid, and supercritical fluid chromatography as well as capillary electrophoresis. The derivative test relies on the symmetry of the inflection points and the maximum and minimum values of the derivative. The Gaussian test is a constrained curve fitting approach and determines the residuals. The residual pattern graphically allows the user to assess the problematic regions in a given peak, e.g., concurrent tailing or fronting, something which cannot be easily done with other current methods. The template provided in MS Excel automates this process. The total peak shape analysis extracts the peak parameters from the upper sections (>80% height) of the peak rather than the half height as is done conventionally. A number of situations are presented and the utility of this approach in solving practical problems is demonstrated. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. A Study on the Effects of Position Change on the Liver Shape on Radioisotope Scan

    International Nuclear Information System (INIS)

    Hong, Kee Suk; Choi, Du Hyok; Yang, Young Tae; Koh, Chang Soon

    1982-01-01

    For this study, the authors obtained and examined anterior views of the liver and spleen in two different positions, upright and supine, of 39 normal subjects and 20 patients with hepatic pathology by means of 99m Tc-colloid and gamma camera. This examination confirms the following findings. In general, it is shown, left lobe of the liver in upright position becomes longer in height than in supine position, while the distance between lateral margin of the liver and that of spleen becomes father in with in supine position than in upright position. The upper margin of liver moves more downward in upright position than in supine. It is noticeable that as for 5 cases with severe chronic liver disease, there is minimal alteration of the liver shape between in two positions. The comparison of the both positions for the better liver scan shows the following findings. Prominent caudate and/or left lobe are marked in the upright position in 16 cases out of the total 59, while none is found in the supine. The false cold area in lower part of the liver disappears in 7 cases in the upright position, while only one shows the disappearance of the false cold area in the supine. Left liver margin due to close contact of spleen is blurred in 3 cases in the upright position. In total 23 cases out of 59 support that the upright position is better for the liver scan, while only 4 cases support the supine position is better. These findings support two assumptions. One is that upright view can be expected more improved resolution than supine view for liver scan. Second is that minimal change of the liver shape in both views indicate the serious abnormality in the liver.

  5. Effect of indentation temperature on nickel-titanium indentation-induced two-way shape-memory surfaces

    International Nuclear Information System (INIS)

    Brinckmann, Stephan A.; Frensemeier, Mareike; Laursen, Christopher M.; Maier, Hans J.; Britz, Dominik; Schneider, Andreas S.; Mücklich, Frank; Frick, Carl P.

    2016-01-01

    This study investigated the effect of temperature on indentation-induced one-way and two-way shape memory properties in Ti-50.3 at% Ni alloy. Indentation temperatures ranged from below the martensite finish temperature (M f ) to above the austenite finish temperature (A f ) with the explicit intent of varying the indented phase. Samples used in the study were characterized by differential scanning calorimetry and transmission electron microscopy (TEM). The topographical behavior of the shape memory effect was investigated through Vickers indentation and laser scanning 3D confocal measurements. The magnitudes of deformation recovery associated with the one-way and two-way shape-memory effect (OWSME, TWSME) decreased with increasing indentation temperatures, which is a reflection of the decreasing volume of material experiencing martensitic reorientation during indentation. Indented and subsequently planarized samples exhibited TWSME protrusions when thermally cycled. Laser scanning measurements were used to characterize the height of the protrusions as increasing depths of material were polished away, which provided insight into the overall affected volume beneath the indent. As indentation temperatures increased, both the height of the protrusions, and consequently the polish depth necessary to completely remove the effect, decreased. TEM investigations revealed that directly underneath a nanoindent the microstructure was very fine due to the high-strain deformation; this was contrasted with a much coarser grain size in the undeformed bulk material. Overall these results strongly imply that the deformation recovery associated with the OWSME and TWSME can be maximized by indenting at temperatures at M f or below because the volume of deformed microstructure beneath the indent is maximized. This finding has important practical value for any potential application that utilizes indentation-induced phase transformation deformation recovery in NiTi.

  6. Effect of indentation temperature on nickel-titanium indentation-induced two-way shape-memory surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Brinckmann, Stephan A. [University of Wyoming, Mechanical Engineering Department, Laramie (United States); Frensemeier, Mareike [INM - Leibniz Institute for New Materials, Saarbrücken (Germany); Laursen, Christopher M. [University of Wyoming, Mechanical Engineering Department, Laramie (United States); Maier, Hans J. [Leibniz Universität Hannover, Institut für Werkstoffkunde (Materials Science), Garbsen (Germany); Britz, Dominik [Saarland University, Department of Materials Science and Engineering, Saarbrücken (Germany); Schneider, Andreas S. [AG der Dillinger Hüttenwerke, Department for Research, Development and Plate-Design, Dillingen (Germany); Mücklich, Frank [Saarland University, Department of Materials Science and Engineering, Saarbrücken (Germany); Frick, Carl P., E-mail: cfrick@uwyo.edu [University of Wyoming, Mechanical Engineering Department, Laramie (United States)

    2016-10-15

    This study investigated the effect of temperature on indentation-induced one-way and two-way shape memory properties in Ti-50.3 at% Ni alloy. Indentation temperatures ranged from below the martensite finish temperature (M{sub f}) to above the austenite finish temperature (A{sub f}) with the explicit intent of varying the indented phase. Samples used in the study were characterized by differential scanning calorimetry and transmission electron microscopy (TEM). The topographical behavior of the shape memory effect was investigated through Vickers indentation and laser scanning 3D confocal measurements. The magnitudes of deformation recovery associated with the one-way and two-way shape-memory effect (OWSME, TWSME) decreased with increasing indentation temperatures, which is a reflection of the decreasing volume of material experiencing martensitic reorientation during indentation. Indented and subsequently planarized samples exhibited TWSME protrusions when thermally cycled. Laser scanning measurements were used to characterize the height of the protrusions as increasing depths of material were polished away, which provided insight into the overall affected volume beneath the indent. As indentation temperatures increased, both the height of the protrusions, and consequently the polish depth necessary to completely remove the effect, decreased. TEM investigations revealed that directly underneath a nanoindent the microstructure was very fine due to the high-strain deformation; this was contrasted with a much coarser grain size in the undeformed bulk material. Overall these results strongly imply that the deformation recovery associated with the OWSME and TWSME can be maximized by indenting at temperatures at M{sub f} or below because the volume of deformed microstructure beneath the indent is maximized. This finding has important practical value for any potential application that utilizes indentation-induced phase transformation deformation recovery in NiTi.

  7. Into the development of a model to assess beam shaping and polarization control effects on laser cutting

    Science.gov (United States)

    Rodrigues, Gonçalo C.; Duflou, Joost R.

    2018-02-01

    This paper offers an in-depth look into beam shaping and polarization control as two of the most promising techniques for improving industrial laser cutting of metal sheets. An assessment model is developed for the study of such effects. It is built upon several modifications to models as available in literature in order to evaluate the potential of a wide range of considered concepts. This includes different kinds of beam shaping (achieved by extra-cavity optical elements or asymmetric diode staking) and polarization control techniques (linear, cross, radial, azimuthal). A fully mathematical description and solution procedure are provided. Three case studies for direct diode lasers follow, containing both experimental data and parametric studies. In the first case study, linear polarization is analyzed for any given angle between the cutting direction and the electrical field. In the second case several polarization strategies are compared for similar cut conditions, evaluating, for example, the minimum number of spatial divisions of a segmented polarized laser beam to achieve a target performance. A novel strategy, based on a 12-division linear-to-radial polarization converter with an axis misalignment and capable of improving cutting efficiency with more than 60%, is proposed. The last case study reveals different insights in beam shaping techniques, with an example of a beam shape optimization path for a 30% improvement in cutting efficiency. The proposed techniques are not limited to this type of laser source, neither is the model dedicated to these specific case studies. Limitations of the model and opportunities are further discussed.

  8. Is interpolation cognitively encapsulated? Measuring the effects of belief on Kanizsa shape discrimination and illusory contour formation

    Science.gov (United States)

    Keane, Brian P.; Lu, Hongjing; Papathomas, Thomas V.; Silverstein, Steven M.; Kellman, Philip J.

    2012-01-01

    Contour interpolation is a perceptual process that fills-in missing edges on the basis of how surrounding edges (inducers) are spatiotemporally related. Cognitive encapsulation refers to the degree to which perceptual mechanisms act in isolation from beliefs, expectations, and utilities (Pylyshyn, 1999). Is interpolation encapsulated from belief? We addressed this question by having subjects discriminate briefly-presented, partially-visible fat and thin shapes, the edges of which either induced or did not induce illusory contours (relatable and non-relatable conditions, respectively). Half the trials in each condition incorporated task-irrelevant distractor lines, known to disrupt the filling-in of contours. Half of the observers were told that the visible parts of the shape belonged to a single thing (group strategy); the other half were told that the visible parts were disconnected (ungroup strategy). It was found that distractor lines strongly impaired performance in the relatable condition, but minimally in the non-relatable condition; that strategy did not alter the effects of the distractor lines for either the relatable or non-relatable stimuli; and that cognitively grouping relatable fragments improved performance whereas cognitively grouping non-relatable fragments did not. These results suggest that 1) filling-in effects during illusory contour formation cannot be easily removed via strategy; 2) filling-in effects cannot be easily manufactured from stimuli that fail to elicit interpolation; and 3) actively grouping fragments can readily improve discrimination performance, but only when those fragments form interpolated contours. Taken together, these findings indicate that discriminating filled-in shapes depends on strategy but filling-in itself may be encapsulated from belief. PMID:22440789

  9. Effects of Raindrop Shape Parameter on the Simulation of Plum Rains

    Science.gov (United States)

    Mei, H.; Zhou, L.; Li, X.; Huang, X.; Guo, W.

    2017-12-01

    The raindrop shape parameter of particle distribution is generally set as constant in a Double-moment Bulk Microphysics Scheme (DBMS) using Gama distribution function though which suggest huge differences in time and space according to observations. Based on Milbrandt 2-mon(MY) DBMS, four cases during Plum Rains season are simulated coupled with four empirical relationships between shape parameter (μr) and slope parameter of raindrop which have been concluded from observations of raindrop distributions. The analysis of model results suggest that μr have some influences on rainfall. Introducing the diagnostic formulas of μr may have some improvement on systematic biases of 24h accumulated rainfall and show some correction ability on local characteristics of rainfall distribution. Besides,the tendency to improve strong rainfall could be sensitive to μr. With the improvement of the diagnosis of μr using the empirically diagnostic formulas, μr increases generally in the middle- and lower-troposphere and decreases with the stronger rainfall. Its conclued that, the decline in raindrop water content and the increased raindrop mass-weighted average terminal velocity directly related to μr are the direct reasons of variations in the precipitation.On the other side, the environmental conditions including relative humidity and dynamical parameters are the key indirectly causes which has close relationships with the changes in cloud particles and rainfall distributions.Furthermore,the differences in the scale of improvement between the weak and heavy rainfall mainly come from the distinctions of response features about their variable fields respectively. The extent of variation in the features of cloud particles in warm clouds of heavy rainfall differs greatly from that of weak rainfall, though they share the same trend of variation. On the conditions of weak rainfall, the response of physical characteristics to μr performed consistent trends and some linear features

  10. Effect of the laser spot shape on spatial distribution of the ion bunch accelerated in a superstrong field

    International Nuclear Information System (INIS)

    Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" data-affiliation=" (Public Limited Company Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" >Komarov, V M; Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" data-affiliation=" (Public Limited Company Scientific research Institute for Optoelectronic Instrument Engineering, Leningrad region (Russian Federation))" >Charukhchev, A V; S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" data-affiliation=" (Federal State Unitary Enterprise All-Russian Scientific Center S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" >Andreev, A A; S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" data-affiliation=" (Federal State Unitary Enterprise All-Russian Scientific Center S.I.Vavilov State Optical Institute (FSUE GOI), St.Petersburg (Russian Federation))" >Platonov, K Yu

    2014-01-01

    We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3 – 4) × 10 18 W cm -2 . Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90°. (interaction of laser radiation with matter. laser plasma)

  11. Effects of boron and aging on mechanical properties and martensitic temperatures in Cu-Zn-Al shape-memory alloys

    International Nuclear Information System (INIS)

    Han, Y.S.; Kim, Y.G.

    1987-01-01

    This work is concerned with the effects of added boron (0.1 w/o) on mechanical properties and martensitic transformation temperatures (Ms) of the Cu - 14.0 Zn - 8.5. Al shape memory alloy. The composition was designed to have Ms temperature in the vicinity of 100 0 C. The influence of applying step quenching on the variation in Ms temperatures has been studied in boron-free Cu - 14.0 Zn - 8.5 Al and boron-containing Cu - 14.0 Zn 8.5 Al - 0.1 B alloys. Aging kinetics and transformation temperatures have been determined by electrical resistivity measurements

  12. Effect of the laser spot shape on spatial distribution of the ion bunch accelerated in a superstrong field

    Energy Technology Data Exchange (ETDEWEB)

    Komarov, V M; Charukhchev, A V [Public Limited Company " Scientific research Institute for Optoelectronic Instrument Engineering" , Leningrad region (Russian Federation); Andreev, A A; Platonov, K Yu [Federal State Unitary Enterprise All-Russian Scientific Center " S.I.Vavilov State Optical Institute" (FSUE GOI), St.Petersburg (Russian Federation)

    2014-12-31

    We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3 – 4) × 10{sup 18} W cm{sup -2}. Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90°. (interaction of laser radiation with matter. laser plasma)

  13. Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression

    OpenAIRE

    Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E.; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

    2016-01-01

    This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s−1 (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hystere...

  14. On formal structure of constitutive equations for materials exhibiting shape memory effects

    International Nuclear Information System (INIS)

    Dobovsek, I.

    2000-01-01

    A derivation of constitutive equations in a general three-dimensional setting is described, based on an additive decomposition of the rate of deformation tensor. The rate of deformation tensor is assumed to consist of an elastic part, a thermoelastic part, a plastic part, a part due to shape memory transformation, and a part due to phase transformation. The thermoelastic part due to thermoelastic coupling accounts for the influence of temperature near phase transformation, while the plastic part is taken in the form of classical J 2 flow theory of plasticity with combined isotropic and kinematic hardening, where the back stress represents a tensor of orientational microstresses. It is assumed that the phase transformation part depends on the first and the second invariant of the tensor of crystallographic distortion, on the deviatoric part of the stress tensor, and on a special evolution parameter describing the rate of forming of a new phase. The elastic part of the rate of deformation tensor is connected with the objective rate of Cauchy stress through the tensor of elastic compliance. As a result, a general form of derived constitutive equations exhibits a similar structure as constitutive relations in finite deformation plasticity. (orig.)

  15. Simultaneous masking additivity for short Gaussian-shaped tones: spectral effects.

    Science.gov (United States)

    Laback, Bernhard; Necciari, Thibaud; Balazs, Peter; Savel, Sophie; Ystad, Sølvi

    2013-08-01

    Laback et al. [(2011). J. Acoust. Soc. Am. 129, 888-897] investigated the additivity of nonsimultaneous masking using short Gaussian-shaped tones as maskers and target. The present study involved Gaussian stimuli to measure the additivity of simultaneous masking for combinations of up to four spectrally separated maskers. According to most basilar membrane measurements, the maskers should be processed linearly at the characteristic frequency (CF) of the target. Assuming also compression of the target, all masker combinations should produce excess masking (exceeding linear additivity). The results for a pair of maskers flanking the target indeed showed excess masking. The amount of excess masking could be predicted by a model assuming summation of masker-evoked excitations in intensity units at the target CF and compression of the target, using compressive input/output functions derived from the nonsimultaneous masking study. However, the combinations of lower-frequency maskers showed much less excess masking than predicted by the model. This cannot easily be attributed to factors like off-frequency listening, combination tone perception, or between-masker suppression. It was better predicted, however, by assuming weighted intensity summation of masker excitations. The optimum weights for the lower-frequency maskers were smaller than one, consistent with partial masker compression as indicated by recent psychoacoustic data.

  16. Effect of Leg-to-Body Ratio on Body Shape Attractiveness.

    Science.gov (United States)

    Kiire, Satoru

    2016-05-01

    Recent studies have examined various aspects of human physical attractiveness. Attractiveness is considered an evolved psychological mechanism acquired via natural selection because an attractive body reflects an individual's health and fertility. The length of the legs is an often-emphasized aspect of attractiveness and has been investigated using the leg-to-body ratio (LBR), which reflects nutritional status of the infant, health status, fecundity, and other factors that are predictive of physical fitness. However, previous studies of leg length and physical fitness have produced mixed results. The present study investigated the relationship between LBR, defined as the height to perineum divided by total height, and perceived attractiveness. Three-dimensional stimuli (11 male and 11 female) were constructed with various LBR features. Each stimulus was rated by 40 women and 40 men in Japan on a 7-point scale. The results showed that the values closest to the average LBRs were rated as the most attractive. Furthermore, by fitting a quadratic curve on the relationship between attractiveness and LBR, an inverted U-shaped curve with the peak located at the average LBR was observed. In addition, high LBR values were rated as more attractive in females, whereas the opposite was true for males. These results suggest that average LBR is indicative of good health and good reproductive potential, whereas more extreme values are avoided because they could be indicative of diseases and other maladaptive conditions.

  17. Effect of laser beam on temperature distribution on artificial cylindrical shaped hard tissue bones

    Science.gov (United States)

    Al-Akhras, M.-Ali H.; Qaseer, Mohammad-Khair; Albiss, B. A.; Gezawa, Umar S.

    2018-02-01

    Samples from fresh lamb chest bones were made in cylindrical shapes to study the time variation of temperature T as functions of the cylindrical radius and depth when its front surface exposed to a laser beam of 110Mw power and 642nm wavelength. The laser beam was directed at the center of the front surface of the horizontal cylinder. The measurements were done in vacuum and at atmospheric pressure. Our data reveal the linear variation of T with time, followed by a gradual increase before it reaches a plateau value at higher time. This sort of behavior independent of the radius or the depth where the temperature was measured. Moreover, the maximum variation occurs on the front surface where the laser beam was hitting and diminishes gradually with depth deep inside the cylinder. Data at atmospheric pressure showed less changes in temperature. The temperature distribution in bone due to laser irradiation is very important for a rational use of laser therapy as well as in the surgery to minimizes the thermal tissue damage.

  18. Bulk photovoltaic effect in photoconductive metamaterials based on cone-shaped nanoparticles

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Babicheva, Viktoriia; Uskov, Alexander V.

    2014-01-01

    is the directanalogy of the photogalvanic effect known to exist in naturally occurring non-centrosymmetric media. This plasmonic bulk photovoltaic effect is intermediate between the inner photoelectric effect in bulk media and the outer photoelectric effect atmacroscopic interfaces. The results obtained are valuable...... for characterizing photoemission and photoconductive properties of plasmonic nanostructures. They can find many uses for photodetection-related and photovoltaic applications...

  19. Effect of Magnetostatic Interactions on Twin Boundary Motion in NiMnGa Magnetic Shape Memory Alloy

    DEFF Research Database (Denmark)

    Heczko, Oleg; Vokoun, David; Kopecky, Vit

    2015-01-01

    on the initial position of the twin boundary, the magnetic field providing the critical stress varied in the range 832 kA/m. By taking into account the variants sizes and their mutual interactions, we explained the observed dependence of the switching field on the location of the boundary. The resulting match......We investigated the effect of magnetostatic interactions on the field-induced reorientation of martensite variants in Ni50.0Mn27.5Ga22.5. The reorientation, achieved by sweeping a single Type-II twin boundary along the sample, was triggered by a twinning stress of about 0.1 MPa. However, depending...... between model predictions and measurements illustrates the fundamental role played by demagnetization effects and magnetostatic interactions in magnetic shape memory effect....

  20. The effect of shape and mounting on the piezo-resistive response of embedded manganin conductors

    International Nuclear Information System (INIS)

    Winter, R E; Harris, E J

    2006-01-01

    In the 'orthogonal gauge' technique stress gauges mounted to measure both longitudinal and transverse stresses in a shocked matrix allow the shear strength of the matrix material to be determined. A useful measure of the sensitivity of an orthogonal gauge system to changes in the yield strength of the matrix material is provided by the ratio between the resistance change of gauges of a given cross-sectional shape mounted in transverse and longitudinal orientations (the T/L ratio). A low T/L ratio indicates a more sensitive, and therefore more potentially useful, system. A Eulerian hydrocode has been used to compute the resistance change of manganin wires of rectangular cross-section and infinite length embedded in both longitudinal and transverse orientation in steel targets subjected to nominally one-dimensional shocks. Configurations in which the gauges were (a) embedded directly into the steel and (b) mounted within thin strengthless polymer layers were studied. It is shown that in case (a) the T/L ratio reduces as the aspect ratio of the gauge cross-section increases. When the gauges are embedded in a strengthless polymer layer (case (b)), the T/L ratio is lower than when the gauges are embedded directly into the matrix but in this case the aspect ratio of the manganin conductor has little influence on the T/L ratio. The observed resistance changes are explained in terms of the stresses in the gauges. The results give insight into the factors which control resistance change and offer the prospect of improvements to current gauge designs