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Auswahl der wissenschaftlichen Literatur zum Thema „Property Segments“
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Zeitschriftenartikel zum Thema "Property Segments"
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Goodman, S. L., C. Li, S. L. Cooper und R. M. Albrecht. „HVEM and high resolution SEM of polyurethane bulk and surface structure“. Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 936–37. http://dx.doi.org/10.1017/s0424820100106740.
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Segmented polyurethanes (PUs) are composed of alternating blocks of crystalline or glassy urethane “hard segments” and rubbery “soft segments.” Chemical incompatability between hard segment (HS) and soft segment (SS) blocks produces a two-phase structure, which accounts for the elastomeric properties of these polymer systems. Polyurethanes are prepared with different HS and SS components, and HS:SS ratios, for various applications. Knowledge of the 3D morphology is necessary to understand polyurethane structure-property relationships. Although conventional transmission electron microscopy can image some polyurethanes, high voltage electron microscopy (HVEM) causes less radiation damage and images thicker samples at higher resolution, thus a sample region may be imaged at multiple tilt angles to provide 3D information. High resolution scanning electron microscopy (HR-SEM) provides complementary information, and at low accelerating voltages (1-3 keV), images near surface structures.Polyurethanes were examined with hard segments of methylene diphenylene diisocyanate (MDI) and 2000 MW soft segments of polytetramethylene oxide (PTMO), polybutadiene (PBD) and polydimethysiloxane (PDMS).
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Rogério César dos Santos, Ana Clara Oliveira Comby und Ramires Vargas da Silva. „A Curious Property of Octagons“. Scientific Inquiry and Review 3, Nr. 2 (05.06.2019): 01–07. http://dx.doi.org/10.32350/sir.32.01.
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The famous theorem of Van Aubel for quadrilaterals postulates that if squares are built externally on the sides of any quadrilateral, then the two segments that join the opposing centers of these squares are congruent and orthogonal. Inspired by this result and also by the results of Krishna, in this article we will prove the following result of plane geometry: each octagon is associated with a parallelogram, in some cases the parallelogram in question can be degenerate at a point or a segment. This is possible because of complex numbers and basics of analytical geometry.
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Minagawa, Keiji, Hirokazu Okamura, Seizo Masuda, Masami Tanaka, Naoto Gohko, Yuichi Masubuchi, Jun-Ichi Takimoto, Kiyohito Koyama und Takashi Uemura. „Preparation and Property of Model Homogeneous ER Fluids Having Urethane Groups“. International Journal of Modern Physics B 13, Nr. 14n16 (30.06.1999): 1998–2004. http://dx.doi.org/10.1142/s021797929900206x.
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Urethane modified polyether liquids composed of hard and soft segments exhibit either positive or negative ER effect depending on the structure. Here some model compounds of the urethane polymers were synthesized, and the influence of chemical structure, e.g. displacement of hard and soft segments and existence of branches, on the ER effect was studied. It was found that negative ER effect is enhanced by introducing a branched structure in the polyether main-chain or a hard segment at center of the linear polyether.
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Quan, Heng, und Zhen Ya Gu. „Study on the Influences of Domain Structure of Hydrophilic Polyurethane with Partially Crystalline on its Moisture Permeability“. Advanced Materials Research 233-235 (Mai 2011): 281–87. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.281.
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Multiphase, segmented polyurethanes with mixed soft segment phase were prepared from 4,4’- diphenylmethane diisocyanate (Pure MDI), polybutylene adipate (glycol) 2000 (PBA2000) and polyethylene glycol 1000 (PEG1000) with 1,4-butanediol (BDO) as the chain extender. Further more, the relationships between domain separation structure, crystallizability of soft segment and moisture permeability, hydrophilic property, phase inversion temperature (PIT) of the polyurethanes were investigated. The studies show that the chemical structure, concentration of hydrophilic soft monomers and the microphase separation degree of the mixed soft segments from hard segment domain have remarkable effects on the application properties of polyurethane.
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May, Ken. „75.48 A Surprising Property of Parabolic Segments“. Mathematical Gazette 75, Nr. 474 (Dezember 1991): 452. http://dx.doi.org/10.2307/3618634.
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Wu, Rui, Xuke Zhang, Huabin Shao, Qingping Luo, Jun Yang und Diping Xu. „Characterization of influenza A virus with nine segments: Effect gene segment on virus property“. Research in Veterinary Science 93, Nr. 2 (Oktober 2012): 1076–80. http://dx.doi.org/10.1016/j.rvsc.2011.12.020.
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Chang, Chih-Yuan, und Wei-Ru Chen. „Influence of processing variables on quality of unsaturated polyester/E-glass fiber composites manufactured by double-bag progressive compression method“. Advances in Mechanical Engineering 10, Nr. 9 (September 2018): 168781401879853. http://dx.doi.org/10.1177/1687814018798531.
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A hybrid process of articulated resin transfer molding and vacuum-assisted resin infusion, called double-bag progressive compression method, has been invented to fabricate composite parts. In double-bag progressive compression method, the secondary bag is divided into several segments. During resin infusion, the double bag is drawn upward by vacuum, and the initial flow resistance offered by the loose preform is low. Once the resin infusion is completed, the vacuum on the segmented bags is progressively released to ambient pressure, and the segmental compression is sequentially performed until unnecessary resin is completely removed. This research is to experimentally investigate the influence of double-bag progressive compression method processing parameters, including vacuum pressure in the cavity, number of segments, initiating time of the next compression, temperature of the heated air, initiating segment of the heated air, initial height of the mold cavity, and excess infused resin, on the mechanical property of the part. The design of experiments adopts Taguchi’s method. Results show that the double-bag progressive compression method significantly reduces total filling time and maximally increases the flexural modulus of the part by 17.81% as compared with the typical vacuum-assisted resin infusion. A preferable parameter condition is proposed by taking both the flexural modulus and the operation complexity into account.
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Butnaru, Irina, Maria Bruma und Sabyasachi Gaan. „Phosphine oxide based polyimides: structure–property relationships“. RSC Adv. 7, Nr. 80 (2017): 50508–18. http://dx.doi.org/10.1039/c7ra10493f.
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Klusek, Tomasz. „Rozmiary i regionalne zróżnicowanie polskiego rynku nieruchomości rolnych“. Zeszyty Naukowe SGGW - Ekonomika i Organizacja Gospodarki Żywnościowej, Nr. 119 (18.09.2017): 101–17. http://dx.doi.org/10.22630/eiogz.2017.119.28.
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The property market is not a unite market and therefore depending on employed criteria can be divided into various segments. In order to provide an analysis the objective criterion is most often used. It refl ects functions of particular properties and on such basis the segment of agricultural properties can be distinguished. The data on agricultural property sales in the whole country scale as well as in provinces can be employed for various purposes, particularly for defining of structural changes in agriculture. In order to do so it is necessary to recognise the background of the property sales, their scope and structure which is the topic of the paper.
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Alt, Helmut, Sergio Cabello, Panos Giannopoulos und Christian Knauer. „Minimum Cell Connection in Line Segment Arrangements“. International Journal of Computational Geometry & Applications 27, Nr. 03 (September 2017): 159–76. http://dx.doi.org/10.1142/s0218195917500017.
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We study the complexity of the following cell connection problems in segment arrangements. Given a set of straight-line segments in the plane and two points [Formula: see text] and [Formula: see text] in different cells of the induced arrangement: [(i)] compute the minimum number of segments one needs to remove so that there is a path connecting [Formula: see text] to [Formula: see text] that does not intersect any of the remaining segments; [(ii)] compute the minimum number of segments one needs to remove so that the arrangement induced by the remaining segments has a single cell. We show that problems (i) and (ii) are NP-hard and discuss some special, tractable cases. Most notably, we provide a near-linear-time algorithm for a variant of problem (i) where the path connecting [Formula: see text] to [Formula: see text] must stay inside a given polygon [Formula: see text] with a constant number of holes, the segments are contained in [Formula: see text], and the endpoints of the segments are on the boundary of [Formula: see text]. The approach for this latter result uses homotopy of paths to group the segments into clusters with the property that either all segments in a cluster or none participate in an optimal solution.
Dissertationen zum Thema "Property Segments"
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Rose, Sebastian, und Daniel Kamali. „Does Property Segment Distribution Affect the Capital Structure of Real Estate Companies? : An Investigative Study of the Operational Risk within Different Property Segments and its Effect on the Debt Ratio in a Company“. Thesis, KTH, Fastigheter och byggande, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298079.
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The real estate sector is a capital-intensive industry, where the combination of debt and equity is used to finance the property investment. Companies tend to increase the loan-to-value ratio, to use financial leverage. However due to banks being more restrictive with their lending as well as having different ways of assessing risk in different property companies, there is a belief that the loan-to-value ratio is affected by the property segment distribution in a company. Based on previous research, there are many factors that could affect the loan-to-value (LTV) in a company such as size, profitability, revenue growth and cost of debt. This paper aims to examine these factors, as well as the operational risk that might be visible in the property segment distribution. The study was done through using a quantitative approach by investigating the largest real estate companies in each Swedish municipality. 614 Swedish real estate companies were investigated and pooled into an OLS regression model. Based on the regression, there is enough evidence in this paper that shows that factors such as size, profitability, revenue growth and cost of debt all have significant impact on the LTV. Furthermore, no general conclusion regarding the relationship between property segment distribution and LTV was found in this paper. Although, there is evidence that residentials- and small house units affect the LTV positively while industrial units affect the LTV negatively.Fastighetssektorn är en kapitalintensiv bransch där kombinationen av skuld och eget kapital används för att finansiera fastighetsinvesteringar. Företag tenderar att öka belåningsgraden för att använda finansiell hävstång. Däremot på grund av att bankerna på senare år blivit mer restriktiva med sin utlåning och att de har olika sätt att bedöma risker på i olika fastighetsbolag, finn fog att förutsätta att belåningsgraden påverkas av fördelningen av fastighetssegment i ett företag. Baserat på tidigare forskning finns det många faktorer som kan påverka belåningsgraden (LTV) i ett företag, såsom storlek, lönsamhet, intäktsökning och kostnad för lånat kapital. Denna uppsats syftar till att undersöka dessa faktorer samt den operativa risk som kan synliggöras i fördelningen av fastighetssegment. Studien gjordes via ett kvantitativt tillvägagångssätt genom att undersöka de största fastighetsbolagen i alla Sveriges kommuner. 614 svenska fastighetsbolag undersöktes och analyserades i en OLS- regressionsmodell. Baserat på regressionen finns det tillräckligt med bevis i denna uppsats på att faktorer som storlek, lönsamhet, inkomsttillväxt och kostnad för lånat kapital har en betydande inverkan på LTV. Vidare hittades ingen allmän slutsats angående sambandet mellan fördelning av fastighetssegment och LTV i denna uppsats. Det finns dock bevis för att bostäder och småhusenheter påverkar LTV positivt medan industriella enheter påverkar LTV negativt.
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Candela, Garza Eduardo. „Revenue optimization for a hotel property with different market segments : demand prediction, price selection and capacity allocation“. Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113433.
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Thesis: S.M., Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 53-55).
We present our work with a hotel company as an example of how machine learning techniques can be used to improve the demand predictions of a hotel property, as well as its pricing and capacity allocation decisions. First, we build a price-sensitive random forest model to predict the number of daily bookings for each customer market segment. We feed these predictions into a mixed integer linear program (MILP) to optimize prices and capacity allocations at the same time. We prove that the MILP can be equivalently solved as a linear program, and then show that it produces upper and lower bounds for the expected revenue maximization Dynamic Program (DP), and that the gap between the bounds depends on the probabilistic distribution of the demand. Thus, for high prediction accuracies, the optimal value of the DP can be closely approximated by the MILP solution. Finally, numerical results show that the optimized decisions are able to generate an increase in revenue compared to the historical policies, and that the fast running time achieved permits real time policy updates.
by Eduardo Candela Garza.
S.M.
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Waletzko, Ryan Scott. „Determining soft segment structure-property effects in the enhancement of segmented polyurethane performance“. Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46671.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2009.Includes bibliographical references.
Liquid Crystalline Elastomer (LCE)-inspired segmented polyurethane elastomers possessing widely different extents of ordering were created to mimic the hierarchical structure of the continuous matrix and superior mechanical performance of spider silk fibers. The silk's remarkable toughness originates from a fiber morphology that possesses [beta]-pleated crystalline sheets within an amorphous matrix. In the polyurethane materials, various extents of poly(ethylene oxide) (PEO) soft segment ordering were implemented within continuous soft domains that were connected by hexamethylene diisocyanate-butanediol (HDI-BDO) hard segments. Soft segment crystallinity studies revealed the need to optimize the extent of continuous soft domain ordering. Highly crystalline PEO soft segments, while they display good microphase segregation properties, sacrifice extensibility due to their high melting transition temperature. Moderately crystalline PEO soft segments, meanwhile, possess less defined phase segregation but enhanced mechanical properties from their reversible dispersed crystalline soft segment domains. Non-crystalline Pluronic copolymer systems had good mechanical properties that resulted from both a strong hard segment incompatibility and a highly mobile soft segment matrix. Hydrogen-bonded hard domain shearing during in-situ tensile deformation yields oriented hard blocks that align at a preferred tilt angle of ±60° from the strain direction. Extensive alignment and orientation of the moderately-ordered PEO soft segments occurred during deformation, which was consistent with its observed mechanical behavior. Pluronic-containing segmented polyurethanes formed an ordered mesophase in the continuous soft matrix during deformation. A series of cyclic, aliphatic polyurethanes with dicyclohexyl methane diisocyanate (HMDI) hard segments and poly(tetramethylene oxide) (PTMO) soft segments was synthesized to study compositional effects on the extent of soft segment mixing, and how these effects translated to both mechanical and barrier performance. Shorter soft segment chain systems displayed a greater hard segment compatibility, which resulted in materials that were both more rigid mechanically and provided better barrier characteristics.
(cont.) Longer soft segments in the continuous polymer matrix displayed a more phase segregated structure, which enhanced their mechanical properties but sacrificed barrier effectiveness. Incorporation of dimethyl propane diol (DMPD), a branched chain extender, created a completely amorphous polyurethane matrix. Polyurethane/Laponite nanocomposites were also created using particles that were capable of preferentially associating with hard or soft segments. HMDI-BDO-PTMO polyurethane/Laponite nanocomposites demonstrated drastically reduced mechanical performance (~13-fold decrease in toughness and ~10-fold decrease in extensibility). The deteriorated mechanical performance was attributed to the formation of an interconnected hard segment continuous morphology that significantly reduced matrix extensibility. HMDI-DMPDPTMO polyurethane/Laponite composites, on the other hand, only experienced modest reductions in extensibility (-70% of total initial extensibility) while maintaining toughess and increasing initial modulus 10-fold. Mechanical behavior resulted from well-dispersed Laponite clay platelets that reinforced the amorphous polymer matrix while imposing modest chain segmental mobility restrictions.
by Ryan Scott Waletzko.
Ph.D.
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Carlsson, Frida, und Malin Strömberg. „Is there a Real Estate Portfolio Premium? : An Empirical Analysis of Portfolio Premiums“. Thesis, KTH, Fastigheter och byggande, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298065.
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This thesis aims to explore if the existence of portfolio price premiums can be verified and if they differ in time and over property segments. The purpose is to contribute with valuable insights within the field of portfolio premiums in the real estate industry. In order to explore this further a regression model was developed. The model includes six portfolio variables controlling for size in the aspect of transactional value and number of properties included in the portfolio. We further test if the premium varies over property segments and over time. The data was provided by Cushman & Wakefield and consists of 825 property transactions. The results show that a portfolio premium for small, medium and large portfolios with a transactional value over 500 million SEK, and a discount on small portfolios with a transactional value below 500 million SEK is present. The premium was found to be 17.5% for small portfolios, 16.8% for medium sized and 26.3% for large portfolios. While premiums were found for portfolios with a transactional value over 500 million SEK an 13.7% discount was found for small portfolios with a transaction value below 500 million SEK. Which indicates that investors are willing to pay a premium, but only for larger portfolios. Furthermore, the only segment test with significant results were residential and industrial of which residential indicated a discount on small and medium portfolios with a transactional value over 500 million SEK and industrial indicated a discount on small portfolios with a transactional value over 500 million SEK. The test of variation of a portfolio premium over time gave mixed results and showed that investors payed a premium for medium and large portfolios with a transactional value over 500 million SEK during 2010 - 2015.Detta masterarbete syftar till att undersöka fenomenet portföljpremier och bidra till utökad kunskap om premier och möjliga förklaringar till varför de uppkommer. Författarna har undersökt om det går att kvantifiera den påstådda portföljpremien och om denna skiljer sig över fastighetsegmenten och tid. Syftet med arbete är att bidrag med värdefulla insikter och kunskap om portföljpremier inom fastighetsbranschen. För att kunna besvara frågeställningen utvecklade författarna en regressionsmodell. Modellen innehöll sex portföljvariabler som bland annat kontrollerade för storlek i förhållande till transaktionsvärde samt antal fastigheter inkluderade i portföljen. För att undersöka om premien varierade över fastighetssegment och med tid utfördes fem olika segmentstest och två års tester. Data som användes i regressionerna tillhandahölls av Cushman & Wakefield. Resultatet av studien visar att det finns en portföljpremie på små, medelstora och stora fastighetsportföljer med ett transaktionsvärde över 500 millioner kronor. Premien noterades till 17,5% för små portföljer, 16,8% för medelstora portföljer och 26,3% för stora portföljer. Medans en premie noterades för portföljer med ett transaktionsvärde över 500 millioner kronor kunde en rabatt om 13,7% hittas för små portföljer med etttransaktionsvärde under 500 millioner kronor. Segmenttesten som genomfördes gav blandade resultat. De test som gav signifikanta resultat var segmentstest för industri och bostäder. Resultatet av regressionen visade att det finns en rabatt för små och medelstora bostadsportföljer med ett transaktionsvärde överstigande 500 millioner kronor samt en rabatt för små industriportföljer med ett transaktionsvärde över 500 millioner kronor. Utöver segmentstesten gjordes även två tester där författarna testade om premien varierade över tid. Likaså här gav testerna blandade resultat. Det kan konstateras att en premie återfinns för portföljer handlade under perioden 2010 - 2015.
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Tyagi, D. K. „Structure-property relationships in segmented copolymers“. Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/49948.
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The structure-property relationships for various segmented copolymers were investigated. A number of mechanical and thermal characteristics were determined. The morphology was characterized by SAXS with respect to size and dispersion of domains; degree of phase separation and the domain interfacial thickness.
a. Novel segmented copolymers were synthesized using amino terminated polydimethylsiloxane oligomers as the soft component and various hard component. lt was found that the performance of these copolymers was affected by the varying the hard segment linkages, hard segment content, soft segment MW, stiffness of the siloxane backbone, and amount of chain extender. Two-phase nature of these copolymers was verified by dynamic mechanical, thermal, and SAXS studies. The phase separation was found to occur in these copolymers with as little as 6% HS. These materials displayed behavior similar to the segmented polyurethanes and were found to be superior to the unfilled silicone elastomers. The final materials were used as reasonable models for investigating various methods for determining the interfacial layer thickness between the hard and soft phase. Specifically, due to the fact that there is no hard segment length distribution as is the usual case for segmented urethanes, these materials have some degree of model characteristics. Utilizing Porod's law, and appropriate analysis, both positive and negative deviations were found in the systematic series of copolymers with the degree of positive and negative character dependent upon composition. Negative deviations were accounted for in terms of a finite interfacial thickness which turned out to be relatively small as anticipated, while the positive deviations arose due to isolated hard segments that reside within the soft segment matrix, concentration fluctuations. ln calculating the interfacial thickness, several methods were applied and in general, close agreement was obtained. Finally, correlation function analysis in conjunction with determination of the coherent Porod lengths, etc. were determined and discussed accordingly.
b. The structure-property behavior of novel 'water extended' segmented polyurethane-urea copolymers was also investigated. These copolymers were synthesized by utilizing the dehydration characteristics of tertiary alcohols at sufficiently high temperature in weak acidic medium. Mechanical, thermal, dynamic mechanical, and x-ray experiments were carried out to characterize the morphology and properties of these segmented copolymers of systematically varying hard segment content, soft segment MW, block length, and hard segment type. lt was observed that these properties depended primarily on the degree of order in the hard domains and the order could be improved by increasing either the HS content at constant soft segment MW or soft segment molecular weight at the same HS content. The results obtained for these materials were compared with those from conventional polyurethanes to investigate the effect of intermolecular hydrogen bonding on molecular arrangement.
c. The final series of segmented copolymers studied were based on polysulfone and polydimethylsiloxane, synthesized by solution polymerization. lt is shown that by varying the length of the segments for each phase and their relative content, it is possible to alter the mechanical and thermal characteristics. The mechanical response was also influenced according to which phase is predominantly continuous. In addition to dynamic mechanical and SAXS measurements, the evidence of the two-phase structure was obtained by TEM.Ph. D.
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Sheth, Jignesh Pramod. „Investigation of the Influence of Selected Variables on the Solid State Structure-Property Behavior of Segmented Copolymers“. Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/29390.
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Segmented copolymers are a commercially important class of materials that are utilized in a wide variety of applications. In these systems a relatively large number of variables such as backbone chemistry, segment molecular weight, and the overall molecular weight of the copolymer can be independently controlled to engineer materials with targeted properties. Such versatility also means that a large number of variables can influence the morphology and therefore, properties and performance of segmented copolymers. In this dissertation, the influence of selected variables on the solid state structure-property behavior of segmented poly(ether-block-amide), polyurethane, polyurethaneurea, and polyurea copolymers is explored. The specific variables which have been utilized singly or in conjunction with others are hard segment crystallizability, crystallization conditions, hard segment content, soft segment type and molecular weight, nature of hydrogen bonding, extent of inter-segmental hydrogen bonding, segment symmetry, and chain architecture.
In poly(ether-block-amide)s, it was found that the morphology of both the crystalline and the amorphous phase depend upon the polyamide content of the sample and, as expected, the crystallization conditions.
A comparison of polydimethylsiloxane based segmented polyurethanes with their polyurea counterparts demonstrated that for a constant hard segment content the soft segment molecular weight particularly governs the extent of microphase separation in these materials. The nature of hydrogen bonding, monodentate or bidentate, also strongly influences their mechanical response. Remarkably, the polyurea sample with a polydimethylsiloxane molecular weight of 7000 g/mol and a hard segment content of 25 wt % exhibited a remarkable service temperature window (for rubber-like behavior) of ca. 230°C (from -55°C to 175°C) whereas it was ca. 200°C wide (from -55°C to 145°C) for the equivalent polyurethane sample. The extremely high chemical incompatibility between the polydimethylsiloxane of sufficiently high molecular weight and urethane or urea segment is expected to generate a relatively sharp interface between the soft matrix and the dispersed hard domains. Therefore, a polyether co-soft segment was incorporated in a controlled manner along the chain backbone, which resulted in inter-segmental hydrogen bonding between the ether and the urea segments. The consequent segmental mixing gave rise to a gradient interphase, which led to a significant improvement in the tensile strength, and elongation at break in selected polydimethylsiloxane segmented polyurea copolymers.
The importance of the hydrogen bonding network in model polyurethaneurea copolymers was also explored by utilizing LiCl as molecular probe. It has been demonstrated that hydrogen bonding plays an important role, over and above microphase separation, in promoting the long-range connectivity of the hard segments and the percolation of the hard phase through the soft matrix. The incorporation of hard segment branching in these polyurethaneurea also reduced the ability of the hard segments to pack effectively and establish long-range connectivity. The disruption of the percolated hard phase resulted in a systematic softening of the copolymers.
The role of chain architecture in governing the structure/property/processing of segmented was also investigated by comparing highly branched segmented polyurethaneureas with their linear analogs. These copolymers were based on poly(propylene oxide) or poly(tetramethylene oxide) as the soft segments The highly branched copolymers utilized in this dissertation were able to develop a microphase morphology similar to their linear analogs. Particularly noteworthy, and surprising, was the observation of weak second order interference shoulder in the respective small angle X-ray scattering profiles of the highly branched samples based on poly(propylene oxide) of MW 8200 and 12200, indicating the presence of at least some level of long-range order of the hard domains in these samples. Tapping-mode atomic force microscopy phase images of these two samples clearly confirmed the small angle X-ray scattering results. In addition to the strain induced crystallization of the poly(tetramethylene oxide) MW 2000 g/mol based linear polyurethaneureas, the highly branched analog of this sample also exhibited similar behavior at ambient temperature and uniaxial deformation of ca. 400 % strain. Wide angle X-ray scattering confirmed the above observation. The reduced ability of the branched polymers to entangle resulted in slightly poorer mechanical properties, such as tensile strength, elongation at break, and stress relaxation as compared to their linear analogs. However, primarily due to their reduced entanglement density, the branched polyurethaneureas had significantly lower ambient temperature solution viscosity as compared to their linear polyurethaneurea analogs. Therefore, these highly branched polyurethaneureas can be more easily processed than the latter materials.
Finally, it was demonstrated that non-chain extended segmented polyurethane and polyurea copolymers in which the hard segment is based on only a single diisocyanate molecule may well exhibit properties, such as the breadth of the service window, the average plateau modulus, stiffness, tensile strength, and elongation at break that are similar to chain extended segmented copolymers that possess distinctly higher hard segment content. A careful control of the hard segment symmetry and the nature of the hydrogen bonding is necessary to achieve such improved performance in the non-chain extended systems. Therefore, the results of this study provide new direction for the production of thermoplastic segmented copolymers with useful structural properties.Ph. D.
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Chang, Zhengmian. „Synthesis and Properties of Novel Triptycene-containing Segmented Polyurethanes and Semicrystalline Polysulfone-polyester Multiblock Copolymers“. Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73294.
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Segmented copolymers are important polymers with attractive properties and wide applications. In this dissertation, segmented polyurethanes containing triptycene units and multiblock copolymers containing poly(arylene ether sulfone) (PAES) and poly(1,4-cyclohexyldimethylene terephthalate) (PCT) segments were synthesized and systematically studied.
Investigation of the influence of the bulky triptycene structure on the morphologies and properties of segmented polyurethanes was carried out by using triptycene-1,4-hydroquinone bis(2-hydroxyethyl)ether (TD) as the chain extender. Segmented polyurethanes based on poly(tetramethylene glycol) (PTMG) of 1000 g/mol were synthesized using a two-step polymerization procedure. Hydroquinone bis(2-hydroxyethyl)ether (HQEE) was used for the purpose of comparison. Hard segments with different bulkiness and flexibility were prepared with hexamethylene diisocyanate (HDI) and 4,4'-methylenebis(phenyl isocyanate) (MDI), and HQEE or TD as chain extenders. The incorporation of bulky TD and less flexible MDI significantly inhibited hydrogen bonding based on the Fourier transform infrared (FTIR) results. In addition, the microphase separation was also disturbed by the bulky and less flexible hard segments with confirmation from tapping mode atomic force microscopy (AFM) and small angle X-ray scattering (SAXS). The flexible HDI can be used to overcome the bulkiness of triptycene, promote microphase separation, and enhance mechanical properties.
Novel PTMG based soft segments containing triptycene units were also prepared with number average molecular weight (Mn) around 2500 g/mol. Then this soft segment was reacted with MDI and HQEE to prepare segmented polyurethanes. Soft segments such as hydroquinone (HQ) containing PTMG (Mn = 2100 g/mol), and pure PTMGs (Mn = 1000 and 2000 g/mol) were used for comparison. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) results demonstrated that triptycene units led to an increased glass transition temperature (Tg) and an elimination of the crystallization of the soft segments. The absence of strain hardening for the triptycene-containing sample suggested a suppressed strain induced crystallization of soft segments, which was also confirmed by the analysis of wide-angle X-ray diffraction (WAXD) on the films strained to 370 %.
Crystallizable PCT segments were copolymerized with PAESs to enhance solvent resistance and mechanical properties. PAES oligomers (Mn = 2000 g/mol) were first synthesized, and then reacted with dimethyl terephthalate (DMT) and 1,4-cyclohexanedimethanol (CHDM). Weight percentages of PCT segments were gradually changed from 20 wt% to 80 wt%. With PCT content greater than 50 wt%, crystallinity was observed by DSC, DMA, and WAXD. The extent of crystallinity of the copolymers was dependent on the wt% of PCT. Furthermore, crystallization behavior of copolymers based on two CHDMs with different isomer ratios (cis/trans 30/70 and all trans) were studied. Due to their more symmetric structure, copolymers based on all trans CHDM exhibited a higher extent of crystallization.Ph. D.
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Tamami, Mana. „Tailored Architectures of Ammonium Ionenes“. Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/35933.
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The synthesis and characterization of a variety of ammonium ionenes from water-soluble coatings to high-performance elastomers are discussed. Water-soluble random copolymer ionenes were synthesized using the Menshutkin reaction from 1,12-dibromododecane, N,N,N⠲,N⠲-tetramethyl-1,6-hexanediamine, and 1,12-bis(N,N-dimethylamino)dodecane. The absolute molecular weights were determined for the first time using a multiangle laser light scattering detector in aqueous size exclusion chromatography and the weight-average molecular weights of these ionenes were in the range of 17,000-20,000 g/mol. Charge density increased with increasing molar ratio of N,N,N⠲,N⠲-tetramethyl-1,6-hexanediamine and the glass transition temperature (Tg) increased from 69 °C to 90 °C as the charge density increased. Small angle x-ray scattering (SAXS) showed isotropic scattering patterns for these ionenes. A limited study on cytotoxicity of these ionenes showed no direct correlation between charge density and cell viability for human brain microvascular endothelial cell line.
A series of low hard segment (HS) content, poly(propylene glycol) (PPG)-based ammonium ionenes were synthesized using a Menshutkin reaction from bromine end-capped PPG oligomers (prepared using acid-chloride reactions) and N,N,Nâ ²,Nâ ²-tetramethyl-1,6-hexanediamine. Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, titration analyses, and 1H NMR spectroscopy, confirmed the difunctionality of bromine end-capped PPG oligomers. Thermal analysis revealed Tgâ s of -60 °C, comparable to pure PPG, using differential scanning calorimetery (DSC), dynamic mechanical analysis (DMA) confirming microphase separation, and an onset of degradation (Td) at 240 °C.
Synthesis of a series of random block copolymer ammonium ionenes with an aliphatic 1,12-dibromododecane as part of the hard segment (33 wt% HS) enhanced film formation and supported microphase separation property. The Td and Tg did not change compared to PPG-ionenes with lower HS content. DMA and tensile testing demonstrated the influence of soft segment (SS) molecular weight and hard segment (HS) content on the mechanical properties of segmented ammonium ionenes. DMA showed the onset of flow, ranging from 100-140 ºC for 1K and 2K g/mol PPG-based ionenes respectively. SAXS revealed a Bragg distance scaled with soft segment molecular weight and ranged from 6.6 to 23.4 nm for 1K to 4K g/mol PPG-based ionenes, respectively.
An investigation of the salt-responsive solubility property of random block copolymer PPG-ionenes revealed a dependence on PPG molecular weight. The 1K g/mol PPG-based ionenes with a hydrophilic (HPL)/hydrophobic (HPB) value ranging from one to three showed solubility in both water and one wt% NaCl aqueous solutions. The 2K g/mol PPG-based ionenes containing HPL/HPB value of two to 15 showed cloudy dispersions in water and one wt% NaCl solutions. The 4K g/mol PPG-based ionenes possessed the salt-responsive character; 4K g/mol PPG-based ionenes with HPL/HPB values of one to 12 showed milky dispersions in water, suspended particles in one wt% NaCl solutions and film precipitation at a HPL/HPB molar ratio of 19.
Master of Science
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Klinedinst, Derek Bryan. „Structure–Property Relationships Of: 1) Novel Polyurethane and Polyurea Segmented Copolymers and 2) The Influence of Selected Solution Casting Variables on the Solid State Structure of Synthetic Polypeptide Films Based on Glutamate Chemistry“. Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/29527.
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The foundational studies of this dissertation concern the characterization of segmented polyurethanes and polyureas synthesized without the use of chain extendersâ molecules that are typically used to promote a microphase separated morphology that gives these materials their useful characteristics. Polyurethanes in which a single asymmetric diisocyanate comprising the whole of the hard segment were found to display poor microphase separation. Conversely, polyurethanes in which a single symmetric diisocyanate composed the hard segment were found to display good microphase separation. The more efficient packing of the symmetric hard segments also led to an increase in hard segment connectivity and hence higher values of storage moduli in these systems. When hydroxyl-terminated diisocyanates were replaced with amine-terminated diisocyanates, polyureas were formed. Here too, diisocyanate symmetry was found to play a key role with symmetric diisocyanates leading to better microphase separation. In addition, the polyurea materials displayed broader service temperature windows than their polyurethane counterparts as the relatively stronger bidentate hydrogen bonding replaced monodentate hydrogen bonding in these materials. A thread-like, microphase separated morphology was visually confirmed using atomic force microscopy. Other techniques such as ambient temperature tensile testing, and wide and small angle x-ray scattering were employed to confirm the presence of the microphase separated structure.
The investigation into the effects of diisocyanate chemistry and its symmetry was broadened to incorporate non-chain extended polyurethane materials with different soft segment molecular weights, as well as polyurethanes that did contain chain extenders. Once again the effect of using symmetric versus asymmetric diisocyanates was evident in the structureâ property behavior of these systems, with symmetric diisocyanates forming materials that displayed better microphase separation and more connectivity of their hard domains.
Lastly, in a departure from the segmented copolymer area, a study was conducted into the influence of casting variables on the solid-state structure of synthetic polypeptide films based on glutamate chemistry. The effect of solvent evaporation was determined to play a key role in the morphology of these polypeptide films. Measured small angle light scattering patterns were compared to computer calculated patterns to reveal information about the structure, shape, and length scale of the polypeptide structure.Ph. D.
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Veal, Michael Joseph. „Studies related to linear segmented copolyurethanes : the development of quantitative analytical procedures for copolyurethane precursors and the determination of structure/property ...........which find application in footwear“. Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235600.
Der volle Inhalt der QuelleBücher zum Thema "Property Segments"
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Cooper, Stuart L. Characterization and structure-property relations of segmented polyurethanes. Lancaster: Technomic Pub., 1987.
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2
Office, General Accounting. Tax policy: Information on the stock and mutual segments of the life insurance industry : fact sheet for the chairman, Subcommittee on Health, and the chairman, Subcommittee on Select Revenue Measures, Committee on Ways and Means, House of Representatives. Washington, D.C: The Office, 1988.
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Lyne, J. Structure-property relationships in non-linear segmented copolyurethanes for use in reaction injection moulding rim. Manchester: UMIST, 1990.
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Foundations of Insurance Production: Commercial Property Insurance - Segment C. 2. Aufl. Insurance Institute of America, 2002.
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Foundations of Insurance Production Segment C: Commercial Property Insurance. Insurance Institute of America, 1996.
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Office, General Accounting. Tax policy: Information on the stock and mutual segments of the life insurance industry : fact sheet for the chairman, Subcommittee on Health, and the chairman, Subcommittee on Select Revenue Measures, Committee on Ways and Means, House of Representatives. Washington, D.C: The Office, 1988.
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Franco, Caroline Sant’Ana, Frederica Richter, Letícia Soster Arrosi und Rafael Niebuhr Maia de Oliveira. Coletânea Direito da Moda. Brazil Publishing, 2021. http://dx.doi.org/10.31012/978-65-5861-065-6.
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This book is a collection of articles, prepared for the 1st State Congress of Fashion Law in Santa Catarina, which took place in Brusque / SC in 2019. There are several topics addressed by the authors, since the Law of Fashion covers all spheres of law. Law and fashion are social elements, both linked to the Economy and the Market, where intellectual property has a strong presence. But, it is not only the intellectual property that should be known by the lawyer who seeks to act and research this segment. Fashion Law covers several spheres of law, which in this market are well intertwined, as you can study in this work. You will have contact with topics of intellectual property, contracts, Labor Law, among others, in order to be able to make a small immersion in the matter, whose view is always the fashion industry, one of the most powerful economic and market spheres today. Obviously, there will be subjects that you will prefer, however, an analysis of all of them in this collection will provide you with a broadening of horizons and a journey through the world of fashion law. Good reading!
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Zimmermann, Eva. Subtractive MLM and Prosodically Defective Morphemes. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198747321.003.0003.
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It is shown how the theory of PDM accounts for instances of subtractive MLM—the empirical phenomenon that is notoriously challenging for the claim that morphology is additive. Two general mechanisms inside PDM can predict subtractive MLM: usurpation of moras and the defective integration of morphemic prosodic nodes. Usurpation can arise if a segment underlyingly lacks a mora and ‘usurps’ it from a neighbouring segment that is hence deprived of it. In the second scenario, a prosodic node that is underlyingly not integrated into the higher/lower prosodic structure is affixed to a base and remains defectively integrated in the output. Given the standard assumption that only elements properly integrated under the highest prosodic node of the prosodic hierarchy are visible for the phonetics, this affix node and everything it dominates remain phonetically uninterpreted. It is shown how all attested types of subtractive MLM in the representative data set fall out from these two basic mechanisms.
Buchteile zum Thema "Property Segments"
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Morano, Pierluigi, und Francesco Tajani. „Estimative Analysis of a Segment of the Bare Ownership Market of Residential Property“. In Lecture Notes in Computer Science, 433–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-39649-6_31.
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Sheth, J. P., und G. L. Wilkes. „Semicrystalline Segmented Poly(Ether-b-Amide) Copolymers: Overview of Solid-State Structure-Property Relationships and Uniaxial Deformation Behavior“. In Handbook of Condensation Thermoplastic Elastomers, 283–323. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2006. http://dx.doi.org/10.1002/3527606610.ch11.
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Mani, Varghese. „Orthognathic Surgery for Mandible“. In Oral and Maxillofacial Surgery for the Clinician, 1477–512. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-1346-6_68.
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AbstractMandible, a horseshoe shaped bone of the facial skeleton, is one of the sturdy bones in humans. Prominent chin is a unique feature of anatomically modern man in comparison with his anthropological ancestors. The simian shelf has reduced to two genial tubercles to which two muscles are attached. The neck of the condyle has narrowed and acts as a buffer to budge by fracture if there is a severe force on the prominent chin. These evolutionary changes facilitated increased space for the tongue as men started articulation. It articulates with the temporal bone by two inter-dependent Temporo-mandibular joints. Mandible is important in both function and aesthetics.Mandible can be cut into multiple pieces and re-arranged and fixed to achieve aesthetic and functional changes. Facial bones have a tremendous capacity to regenerate and heal provided proper blood supply is ensured to the cut segments. Ostoetomies of the mandible can be done on ramus, body, chin, dento-alveolar region, inferior border, etc. Most of these procedures are done intraorally. Technological advancements have aided orthognathic surgery at large. This chapter envisages to elaborate different techniques of osteotomy of mandible.
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Zhang, R. Q., und Abir De. „Theoretical Studies on Formation, Property Tuning and Adsorption of Graphene Segments“. In Physics and Applications of Graphene - Theory. InTech, 2011. http://dx.doi.org/10.5772/15896.
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Morano, Pierluigi, Francesco Tajani und Marco Locurcio. „Land Use, Economic Welfare and Property Values“. In Sustainable Infrastructure, 414–37. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-0948-7.ch018.
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In the paper an analysis of functional correlations of property prices with the main locational and socio-economic variables, which generally contribute to define the market value of properties, has been developed. Locational characteristics are represented by the surfaces of soil used for the main functions, borrowing the logic of the system of classification of CORINE Land Cover (European Commission). The analysis has been contextualized to the 258 municipalities of the Apulia region (Southern Italy), and has been referred to two different moments (years 2006 and 2011), and two different market segments (residential and retail). The functional relationships between property prices and explanatory variables considered, estimated through a software that implements a genetic algorithm, are particularly interesting. The methodology outlined constitutes a valuable reference for the definition of models aimed at supporting, in a more rational and convenient way, public planning decisions and private investment choices.
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Friedman, Lawrence M. „Regulation, Welfare, and the Rise of Environmental Law“. In A History of American Law, 729–48. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190070885.003.0025.
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This chapter discusses changes in American law in the twentieth century covering land use, environmental law, intellectual property, regulation of business, and business law. The twentieth century was a century of land-use controls. An important legal invention was zoning. The central idea of zoning is to divide a town or city into zones or segments and to regulate what kinds of land use are allowed in each of these segments. Some zones will be limited to one-family houses, others will be open to apartment buildings, stores and offices, and even to factories. New York City was a pioneer in the zoning movement. After the state passed an enabling act, New York City adopted the first comprehensive zoning ordinance (1916). Zoning soon spread to city after city. By 1930, it was pretty much the rule in both large and small cities and in the suburbs as well.
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Pankaj, Anju, und Sonal Ayyappan. „Theoretical Concepts and Technical Aspects on Image Segmentation“. In Computer Vision, 2333–48. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5204-8.ch102.
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Image segmentation is the process of partitioning a digital image into multiple segments (super pixels). Segmentation is typically used to locate objects and boundaries in images. The result of segmentation is a set of segments that collectively cover the entire image, or a set of contours extracted from the image. Each of the pixels in a region is similar with respect to some characteristic or computed property. Adjacent regions are significantly different with respect to the same characteristics. A predicate for measuring the evidence for a boundary between two regions using a graph-based representation of the image is defined. An important characteristic of the method is its ability to preserve detail in low-variability image regions and ignoring detail in high variability regions. This chapter discuss basic aspects of segmentation and an application and presents a detailed assessment on different methods in image segmentation and discusses a case study on it.
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Pankaj, Anju, und Sonal Ayyappan. „Theoretical Concepts and Technical Aspects on Image Segmentation“. In Intelligent Analysis of Multimedia Information, 32–47. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-0498-6.ch002.
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Image segmentation is the process of partitioning a digital image into multiple segments (super pixels). Segmentation is typically used to locate objects and boundaries in images. The result of segmentation is a set of segments that collectively cover the entire image, or a set of contours extracted from the image. Each of the pixels in a region is similar with respect to some characteristic or computed property. Adjacent regions are significantly different with respect to the same characteristics. A predicate for measuring the evidence for a boundary between two regions using a graph-based representation of the image is defined. An important characteristic of the method is its ability to preserve detail in low-variability image regions and ignoring detail in high variability regions. This chapter discuss basic aspects of segmentation and an application and presents a detailed assessment on different methods in image segmentation and discusses a case study on it.
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Hale, Jacob, Suzanna Long, Vinayaka Gude und Steven Corns. „Using Trend Extraction and Spatial Trends to Improve Flood Modeling and Control“. In Data Visualization [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96347.
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Effective management of flood events depends on a thorough understanding of regional geospatial characteristics, yet data visualization is rarely effectively integrated into the planning tools used by decision makers. This chapter considers publicly available data sets and data visualization techniques that can be adapted for use by all community planners and decision makers. A long short-term memory (LSTM) network is created to develop a univariate time series value for river stage prediction that improves the temporal resolution and accuracy of forecasts. This prediction is then tied to a corresponding spatial flood inundation profile in a geographic information system (GIS) setting. The intersection of flood profile and affected road segments can be easily visualized and extracted. Traffic decision makers can use these findings to proactively deploy re-routing measures and warnings to motorists to decrease travel-miles and risks such as loss of property or life.
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O’Sickey, Matthew J., Garth L. Wilkes und Bruce D. Lawrey. „Structure-Property Relationships of Poly(urethane-urea)s with Soft Segments Consisting of Ultra-Low Monol Content Poly(propylene glycol) with and without Tri(propylene glycol)“. In Polyurethanes Expo 2001, 191–94. CRC Press, 2020. http://dx.doi.org/10.1201/9780429332609-29.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Property Segments"
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„Market Segments and the Analysis of Property Portfolio Performance“. In Third Conference of the European Real Estate Society: ERES Conference 1996. ERES, 1996. http://dx.doi.org/10.15396/eres1996_110.
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Abduljabar, Ali A., Adrian Porch und David A. Barrow. „Real-time measurements of size, speed, and dielectric property of liquid segments using a microwave microfluidic sensor“. In 2014 IEEE/MTT-S International Microwave Symposium - MTT 2014. IEEE, 2014. http://dx.doi.org/10.1109/mwsym.2014.6848387.
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Shafiei, Somayeh B., Lora Cavuoto und Khurshid A. Guru. „Motor Skill Evaluation During Robot-Assisted Surgery“. In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67607.
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Remote manipulation during robot-assisted surgery requires proficiency in perception, cognition, and motor skills. We aim to understand human motor control in remote manipulation of robotic surgical instrument and attempt to measure motor skills. Three features, smoothness, normalized jerk score, and two-thirds power law coefficient, estimating the motor skills of surgeons were analyzed. These features were calculated through segments, extracted from continuous end-effector trajectories during suturing, knot-tying, and needle-passing surgical tasks, performed by 8 right-handed subjects on bench-top models using da vinci surgical kit control system. Each subject repeated each task five times. Totally 1567 segments were extracted, 413, 437, and 717 segments performed by experts, intermediates, and novice subjects, respectively. Dynamic change of kinematic properties was analyzed to evaluate the relationship between considered features and motor skill level. Results show smoothness is significantly correlated with normalized jerk score and both features are significant measures of expertise levels. Also, results show the power law is violated by many end-effector trajectories and there is no relationship between obeying two-thirds power law, smoothness and jerk. We conclude trajectory is improved from non-smooth and jerky in novices to smooth in expert surgeons. This property may be used for motor skill evaluation. It is unlikely that obeying two-thirds power law be a valid property of all end-effector trajectories. However, power law coefficient may be a discriminant feature for levels of expertise. The results are also applicable in a home-based monitoring platform, to monitor motor functioning improvement of stroke patients during rehabilitation process.
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Jacquet-Richardet, G., F. Moyroud und T. H. Fransson. „An Influence of Shroud Design on the Dynamic and Aeroelastic Behavior of Bladed Disc Assemblies“. In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-191.
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Precise non-linear aeroelastic modeling of shrouded bladed-disc assemblies is generally beyond present capacities and analyses often assume that the behavior of the coupled system remains linear and retains a cyclic symmetrical property. In this paper, several models of shrouded assemblies, in the particular case of fully slipping interfaces, are examined and compared. Considering the cyclic symmetrical property of the structure, only the model where shroud segments can slip and propagation relations are applied in the direction normal to the interface plane, should be used. A reduced model based on a direct discretisation of the whole assembly is presented and validated. The application is based on a first stage shrouded fan. The influence of varying the interface shroud angle is examined in terms of frequency, mode shape and aeroelastic damping.
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Li, Lun, Zhili Zhou, Jishun Li und Yujun Xue. „Virtual Prototype of the Tunnel Boring Machine and Movement Simulation in DIVISION Mockup2000i2“. In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12578.
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The virtual reality is a multi-functional, interactive and immersible technology. As an advanced engineering design technology, the virtual reality technology (VRT) has been widely used in large mining machinery design and manufacturing. The system is based on DIVISION Mockup2000i2 software. Virtual prototype of the Tunnel Boring Machine (TBM) is studied in this paper. In addition, the movement simulation of TBM is completed in DIVISION Mockup2000i2. Firstly, CATIA software is adopted to build the parts of TBM. The TBM is assembled in CATIA too. Secondly, the THEOREM software is applied to convert the assembled model of TBM to another format which can be identified in DIVISION MOCKUP2000i2 software. In order to make the TBM image living, life-like and easy to browse, the light of surface, virtual materials and landmark scenes are set up in DIVISION MOCKUP2000i2 software environment. All motion parameters of the parts are defined before the simulation. Then, the virtual movement simulation of TBM components is analyzed with the behaviors property of MOCKUP. The virtual movement of cutting wheel, screw conveyor machinery and the door of mud out are studied. The virtual movement of segments and segment erector machine are completed by setting up virtual parts and virtual event. Five segments are fixed accurately in a cycle. The relations and interference of the parts movement are examined simultaneity. The hotkey is defined before the simulation, which can trigger the continuous implementation of virtual motion. In addition, a virtual voice is used to enhance the performance of movement simulation. The virtual prototype of TBM being set up and simulated will have positive significance for design inspection, structural analysis and product introduction without TBM physical prototype being manufactured.
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Thacker, Ben H., Cesar J. Carrasco, Robert W. Warke und Bill Amend. „Optimized Sampling Frequencies for Weld Reliability Assessments of Long Pipelines“. In 2004 International Pipeline Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ipc2004-0510.
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This work responds to a need to obtain statistically adequate quantities of input data for probabilistic assessments of girth welded pipelines. It is desirable to limit the data collection efforts to that warranted by overall reliability and confidence requirements. This is motivated by the challenge of limited and/or high-cost access to in-service pipelines for property measurement and flaw inspection. The goal of this work is to develop a methodology for specifying the minimum, cost-optimized sampling frequency for each of the model input parameters in a multiple girth weld fitness-for-service (FFS) assessment. The sampling frequency specifies the number of samples for each of the model variables to minimize the given cost function. The methodology is based on a user-specified confidence level for the computed reliability of a given pipeline segment (or segments), as well as the estimated per-sample cost of obtaining data for each parameter. The methodology is implemented as an add-on module in the GirthRel computer program. By expressing FFS in the language of risk-based inspection and maintenance, tools such as the one developed here will be invaluable to the development of a pipeline risk management system.
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Yao, Zhiyang. „Generating Spiral Paths for Sculptured Surfaces Machining“. In ASME 2006 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/detc2006-99034.
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To machine sculptured surfaces, ball end mills are mainly used to reach the final surface finish requirements. During machining, the cusp height is one of the major factors defining the final surface finish smoothness. A cutter path that maintains a high cutting efficiency as well as a constant cusp height is desired. Spiral curves, with the property of not requiring extra linkage segments between two adjacent arms can be used to generate a smooth cutter path. In this paper, a geometric algorithm for generating spiral cutter paths for ball end milling in machining sculptured surfaces is presented.
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Miglietti, Warren M., John Kearney und Luis Pabon. „Liquid Phase Diffusion Bond Repair of Siemens V84.2, Row 2 Vanes and Alstom Tornado, 2nd Stage Stator Segments“. In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0510.
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During the industrial turbine engine operation of the Siemens V84.2, Row 2 vanes, and the Alstom Tornado, 2nd stage stator segments, “craze-cracking” and isolated thermal fatigue cracks develop during engine operation. Other damages found include pitting and dents resulting from corrosion/erosion and FOD (foreign object damage), respectively. Erosion and oxidation damage is also commonly found on the airfoils. This paper describes the vacuum LPDB (liquid phase diffusion bond) repair process used to repair all of the above-mentioned damage. As a means of qualifying the high temperature diffusion bond process, both metallurgical and mechanical property evaluations were carried out. The metallurgical evaluation consisted of optical and scanning electron microscopy. The wide gap diffusion bonded area consisted of a fine-grained structure with intermetallic phases dispersed both intergranularly and intragranularly. An Energy Dispersive X-ray analysis was also conducted and the results are reported. The chemistry of the repaired area is similar to the base metal which may explain why mechanical tests revealed properties equivalent to that of the base metal. The mechanical evaluations undertaken were tensile tests at room temperature and elevated temperature, as well as stress rupture tests. These results were equivalent to mechanical properties of the IN738 and IN939 Ni-based superalloys, which is the base metal that the above mentioned vanes and stator segments are manufactured from.
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Burkholder, Phil S., Malcolm C. Thomas, Randy Helmink, Donald J. Frasier, Ken Harris und Jacqueline B. Wahl. „CM 186 LC® Alloy Single Crystal Turbine Vanes“. In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-379.
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There is a need to introduce advanced turbine technology at reduced cost. SX superalloy vanes demonstrate excellent engine performance and durability benefits compared to their polycrystalline counterparts. However, their manufacturing cost can be prohibitive due to low casting and solution heat treatment yields due to rejectable grain defects. High purity (carbon and boron free), ultra high creep and fatigue strength SX alloys are limited to low angle boundaries (LABs) normally not exceeding 6° in critical airfoil locations. Carbon (C) and boron (B) containing SX superalloys (Ross, et al., 1996) can accommodate low angle boundaries in the 9°–12° range with an overall sacrifice in creep and fatigue properties. Aero engine vane segments with complex configurations, can result in not only LAB defects exceeding 9°–12° but also high angle grain boundary (HAB) defects ≥ 15° occurring during the SX solidification process. This is further excaberated by recrystallised grains occurring during solution heat treatment from residual casting stresses and associated strain. CM 186 LC® is a hafnium (Hf) containing nickel-base superalloy developed for directionally solidified (DS) columnar grain turbine airfoils. SX casting experience — development and production — has shown the alloy can be readily cast into aero turbine multi-airfoil segments. Mechanical property and turbine engine testing show the alloy can accommodate grain boundaries at least up to 30° resulting in high SX casting yields. The SX vane components are either used as-cast or approximately 50% partial solutioned which avoid any recrystallisation (Rx) problems. Component costs can be < 50% of that of a conventional high purity SX alloy. Mechanical property, oxidation and coating performance characterisation studies on SX CM 186 LC (including DS test pieces) and turbine engine test and application experience show a 72°F (40°C) metal temperature capability improvement (thin wall) over DS MAR M 002 alloy.
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McMaster, Fraser, Hugh Thompson, Michelle Zhang, David Walters und Jonathan Bowman. „Sour Service Corrosion Fatigue Testing of Flowline Welds“. In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29060.
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An examination of the corrosion-fatigue behavior of production quality welds in X65-type pipes was performed. Due to the low cycle operational nature of the production flowline system, the fatigue test frequency was substantially lower (0.01Hz vs. 0.33Hz) than typically utilized during corrosion-fatigue testing. Also the tests were performed at higher stress ranges than previous sour service fatigue tests, which to date have targeted riser fatigue loading regimes. Stress-life (S-N) samples were removed from segments of pipe with outside diameters of 10.75 inch (wall thickness of 1.30 inch) and 9.625 inch (wall thickness of 1.26 inch) containing fully inspected, production-quality circumferential welds. Environments examined included laboratory air conditions as well as deoxygenated brine supplemented by a gas mix of H2S and N2. For all environmental tests performed, the dissolved oxygen levels were maintained at less than 10 ppb during all testing. The measured fatigue life decrease in the curved pipe segments was in the range of 8–110 times due to the combined effect of the material and fluid property variables examined. The results of this work clearly illustrated the impact of sour-service corrosion fatigue, in welded carbon steel pipes, to the multitude of variables involved. Nevertheless, the foregoing experimental work clearly demonstrated the importance of performing environmental relevant testing when considering material and process selection for offshore applications.
Berichte der Organisationen zum Thema "Property Segments"
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Qi, Yan, Ryan Fries, Shambhu Saran Baral und Pranesh Biswas. Evaluating the Costs and Benefits of Snow Fences in Illinois: Phase 2. Illinois Center for Transportation, November 2020. http://dx.doi.org/10.36501/0197-9191/20-020.
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Serving as a windbreak, properly sited and designed snow fences have been proven effective in mitigating the negative impacts of blowing snow. To achieve the best snow-control effects, the ideal locations for snow fences are usually outside the roadway right-of-way. Few efforts have been made to examine the economic efficiency of snow fences and explore ways to reward private landowners. The objective of this project was to develop methodologies for evaluation of the costs and benefits of snow fences in Illinois and identify ways to encourage private landowners’ participation in the snow fence program while keeping it cost-effective. The researchers conducted a literature review as well as agency and landowner surveys. They also acquired crash data, snow fence and blowing snow segment inventory data, and blowing snow removal expenditure data as well as performed benefit-cost analyses of three types of snow fences following Federal Highway Administration guides. The survey results suggested that standing corn rows (SCRs) and structural snow fences (SSFs) were the least intrusive options for landowners and living snow fences (LSFs) with trees were the most intrusive. Some concerns related to LSFs could be reduced by allowing landowners to play a role in the design and plant-selection process. The crash data indicated that no fatal and severe crashes occurred at snow fence segments, while several fatal and severe crashes occurred at blowing snow segments during 2012–2016. The results of the benefit-cost analyses showed that the benefit-cost ratios for LSFs and SSFs are comparable. However, LSFs are favorable over SSFs because little maintenance is needed after the plants are mature. Although SCRs have the highest benefit-cost ratio, the need to renew the agency-landowner agreement annually and the alternating of crops planted may limit their snow-control effectiveness and large-scale implementation. A tool was developed using MS Excel to facilitate the benefit-cost analysis of snow fences.
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Financial Stability Report - First Semester of 2020. Banco de la República de Colombia, März 2021. http://dx.doi.org/10.32468/rept-estab-fin.1sem.eng-2020.
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In the face of the multiple shocks currently experienced by the domestic economy (resulting from the drop in oil prices and the appearance of a global pandemic), the Colombian financial system is in a position of sound solvency and adequate liquidity. At the same time, credit quality has been recovering and the exposure of credit institutions to firms with currency mismatches has declined relative to previous episodes of sudden drops in oil prices. These trends are reflected in the recent fading of red and blue tonalities in the performance and credit risk segments of the risk heatmaps in Graphs A and B.1 Naturally, the sudden, unanticipated change in macroeconomic conditions has caused the appearance of vulnerabilities for short-term financial stability. These vulnerabilities require close and continuous monitoring on the part of economic authorities. The main vulnerability is the response of credit and credit risk to a potential, temporarily extreme macroeconomic situation in the context of: (i) recently increased exposure of some banks to household sector, and (ii) reductions in net interest income that have led to a decline in the profitability of the banking business in the recent past. Furthermore, as a consequence of greater uncertainty and risk aversion, occasional problems may arise in the distribution of liquidity between agents and financial markets. With regards to local markets, spikes have been registered in the volatility of public and private fixed income securities in recent weeks that are consistent with the behavior of the international markets and have had a significant impact on the liquidity of those instruments (red portions in the most recent past of some market risk items on the map in Graph A). In order to adopt a forward-looking approach to those vulnerabilities, this Report presents a stress test that evaluates the resilience of credit institutions in the event of a hypothetical scenario thatseeks to simulate an extreme version of current macroeconomic conditions. The scenario assumes a hypothetical negative growth that is temporarily strong but recovers going into the middle of the coming year and has extreme effects on credit quality. The results suggest that credit institutions have the ability to withstand a significant deterioration in economic conditions in the short term. Even though there could be a strong impact on credit, liquidity, and profitability under the scenario being considered, aggregate capital ratios would probably remain at above their regulatory limits over the horizon of a year. In this context, the recent measures taken by both Banco de la República and the Office of the Financial Superintendent of Colombia that are intended to help preserve the financial stability of the Colombian economy become highly relevant. In compliance with its constitutional objectives and in coordination with the financial system’s security network, Banco de la República will continue to closely monitor the outlook for financial stability at this juncture and will make the decisions that are necessary to ensure the proper functioning of the economy, facilitate the flow of sufficient credit and liquidity resources, and further the smooth functioning of the payment system. Juan José Echavarría Governor