Dissertationen zum Thema „Property segment“

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.

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.

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.
incomplete_metadata

This thesis aims to analyze trends in the area of residential properties within selected locality over a selected period of time. Introduction chapter explains basic terminology of real estate market and later unveils the way how is residential market integrated into real estate market as such. It also describes factors that have significant impact on supply and demand. Next chapter describes residential market and distribution of its particular sectors. Main chapter analyzes selected parameters which affect residential market in the South Moravian Region. Key parameters are demographic movement, income and living standards of residents and its relationship to household, residential construction trends, etc. The final chapter is concerned with housing condition of council flats and houses in the area of Brno metropolis. The analyses contains the trend monitoring of selected factors over a selected period of time.

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.

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.

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.

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,Nâ ²,Nâ ²-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,Nâ ²,Nâ ²-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

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.

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.

碩士
國立成功大學
醫學工程研究所
91
Normal standing is a complex activity both mechanically and neurologically. Using Lagrange’s equation, we validated the three spring-damper-mass model for sagittal sway. Our approach was to derive the multi-segment model and employed springs and dampers to describe muscles and soft tissues characteristic, thus to simplify the complex system in order to gain an insight into the underlying principles of balance activity. There were eight subjects participating in this study. With four separate trials, the subjects were ask to keep balance both on force plate and on the balance plate, which was free to move forwards and backwards. The four trial conditions were (1) stand still on force plate and balance plate, (2) stand on force plate with single joint movement, (3) stand on force plate and keep balance when exerting an impulse force to the subject, (4) stand on balance plate and keep balance when exerting an impulse force to the subject. Results showed that the k、c value increased when the sway size was decreased, and also revealed that positive or negative of the k、c value may changed when the sway size was almost zero or when the sway was going to change its direction . As the stiffness frequency do different between subjects when doing the same trial, this implies stiffness may be used as the dynamic balance evaluation coefficient.

碩士
國立中央大學
化學工程與材料工程研究所
90
Because segment polyurethane has large, complex construction and special microstructure, so it can react so much property. For this, literature did not have much clear result, make so much people can not know the real property of polyurethane. For to know the property of polyurethane, our laboratory use cis-polybutadiene, ozonolysis crack, uncross by lithium aluminum hydride, react a series different Mn= 700~3400 polyol ---- cis HTPB(Hydroxy terminated polyuretadiene), and use HTPB as soft segment, MDI(4,4-diphenylmethane diisocyanate) and different extender EG; PrD; BD; PeD; HD; DD as hard segment, under 50 wt% hard segment content, react a series linear segment copolymer, than use diamond knife and ultra-microtome to crave about 40 nm slice, than use OsO4 to imbue soft segment, finally use TEM to observe the structure of polyurethane, for this, we can know the physical property of polymer by the change of molecule.

Thesis is submitted in partial fulfilment for the degree of Master of Science in Building (Property Development and Management) to the Faculty of Engineering and the Built Environment, School of Construction Economics and Management at the University of the Witwatersrand, Johannesburg, 2017
The research study seeks to determine the most resilient residential real estate market segment throughout the economic cycle waves, for the innercity of Johannesburg, South Africa. The study is prompted by various global reports that subtly suggests a uniform effect to real estate market segments throughout economic cycle waves. Such reports have adopted various indices as proxy to economic cycle waves (e.g. interest rates, current account deficit, gross domestic product, etc.) and house price as proxy to real estate market segments in an attempt to justify the relationship between the proxies. For purposes of this research report, business cycles are employed as proxy to economic cycle waves whilst house prices are also representative of real estate market segments. In a country that ranks third globally on high inequality, with a gini coefficient of 0.63, it is considered improbable – at the very least - that the performance of real estate market segments would react uniformly to the effects of economic cycle waves. The residential sector is opted as a test case, mainly due to growing number of population and the desperate need for housing to accommodate such high population growth levels. The housing challenge needs to be thoroughly understood so that informed and/or adequate planning can be formulated. The research study follows a Pragmatism Philosophy, which allows for mixed method approach in addressing research questions, in order to meet the research aim and objectives. An Explanatory Sequential research design is used as a form of mixed method approach. The process involves collecting both Qualitative and Quantitative data, integrating the two forms of data, and using distinct designs that involves philosophical assumptions and theoretical frameworks. In this case, Quantitative methods are used to explain Qualitative methods. Priority is given to Quantitative data and the two methods are integrated during the interpretation phase of the research study. Empirical analysis using tools such as Quantile Regressions (e.g.OLS regressions) for a period between 2005 (Q1) and 2015 (Q4) are analysed and discussed. Standard errors and covariances were computed using tools such as the Huber-Sandwich methods, to which an Augmented Dickey-Fuller test was conducted to test for the null hypothesis of a unit root in a time series sample. The Breusch-Godfrey Serial Correlation LM test is also used to confirm the absence of serial correlation at four lags. The ARCH LM test is used to show that residuals are homoskedastic, i.e. that there is no evidence of time-varying variance. A negative and significant coefficient appears only the high price sector, suggesting that the business cycle has a negative impact on house prices in the high residential real estate market segment, displaying negative average growth over the period. House prices in the low and medium residential real estate market segments do not respond to movements in the business cycle, on the average. Property size also displayed a negative impact on house prices in the high residential real estate market segment. The autoregressive parameters for house prices in the low and middle residential real estate market segments are statistically significant at 5% and 10%, respectively. Negative and significant coefficient is recorded for the middle residential real estate market segment as well, at the second quantile. In conclusion, the low residential real estate market segment appeared to have been the most resilient residential real estate market segment amongst other residential real estate market segments. The middle residential real estate market segment appears to have been a partially resilient, whilst the high residential real estate market segment appears to have been the least resilient. Given these findings, it is submitted that residential real estate market segments need to be considered or assessed individually, in order to formulate adequate strategies for integrated and sustainable human settlements.
MT2018