To seek better material behaviors, the research of material properties has been mas- sively carried out in both industrial and academic fields throughout the twentieth century. Composite materials are known for their abilities of combining constituent materials in or- der to fulfill the desirable overall material performance. One of the advantages of composite materials is the adjustment between stiffness and lightness of materials in order to meet the needs of various engineering designs. Even though the finite element analysis is mature, composites are heterogeneous in nature and can present difficulties at the structural level with the acceptable computational time. A way of simplifying such problems is to find a way to connect structural analysis with corresponding analysis of representative microstructure of the material, which is normally called micromechanics modeling or homogenization.Generally speaking, the goal of homogenization is to predict a precise material behavior by taking into account the information stored in both microscopic and macroscopic levels of the composites. Of special concern to researchers and engineers is the thermomechanical behavior of composite materials since thermal effect is almost everywhere in real practical cases of engineering. In aerospace engineering, the thermomechanical behaviors of compos- ites are even more important since flight under high speed usually produces a large amount of heat which will cause very high thermal-related deformation and stress.In this dissertation, the thermomechanical behavior of composites will be studied based on the variational asymptotic method for unit cell homogenization (VAMUCH) which was recently developed as an efficient and accurate micromechanics modeling tool. The theories and equations within the code are based on the variational asymptotic method invented by Prof. Berdichevsky. For problems involving small parameters, the traditional asymptotic method is often applied by solving a system of differential equations while the variational asymptotic method is using a variational statement that only solves one functional of such problems where the traditional asymptotic method may apply.First, we relax the assumption made by traditional linear thermoelasticity that not only a small overall strain is assumed to be small but also the temperature variation. Of course, in this case we need to add temperature dependent material properties to VAMUCH so that the secant material properties can be calculated. Then, we consider the temperature field to be point-wise different within the microstructure; a micromechanics model with nonuniformly distributed temperature field will be addressed. Finally, the internal and external loads induced energies are considered in order to handle real engineering structures under their working conditions.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21754号 / 工博第4571号 / 新制||工||1712(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 西脇 眞二, 教授 北村 隆行, 教授 小森 雅晴 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Westernization of Chinese traditional music occupies a significant portion of Chinese music history and has had a tremendous influence on Chinese contemporary music. This dissertation will discuss why almost all contemporary Chinese music has been integrated with Western musical elements. It will also address the evolution of Chinese music, the differences between traditional Chinese music and contemporary Chinese music, the way contemporary Chinese music combines Chinese traditional music with Western music, Chinese peoples’ views towards Chinese traditional music and contemporary music, and the significance of the above with respect to the preservation of Chinese culture and cultural diversity in the world.

A primary emulsion with whey protein isolate (WPI) and hexanoic acid was prepared, and chitosan (Ch) (0.01%, 0.02%, and 0.03%) was added to evaluate its impact on particle size distribution of the emulsion. NaCl (0, 20, 40, and 80 mM) was added to increase ionic interactions to stabilize the multilayer emulsion. Lecithin (0.5%, 1%, 2%, 3 %, w/v) was mixed with the primary emulsion in order to form a multilayer, and casein hydrolysate (CH) was used to stabilize the tertiary emulsion system without the use of NaCl for 28 d at 4 °C. Stable O/W nanoemulsions were generated for use as nano-vesicular vehicles (NVV) to carry Curcumin (CU). Two important variables, (1) addition of casein hydrolysate (CH) (1:50, w/w WPI) and, (2) use of high pressure (140 and 210 MPa), were studied for their effect on the stabilization of monodispersed NVV and persistence of antioxidant activity of the CU as cargo in the NVV throughout storage. Addition of CH reduced nano-particle size and increased emulsion stability with UHPH pressure. The nanoparticle distribution was not changed by the addition of CU. Addition of casein hydrolysate reduced particle size as well as enhanced the positive functional properties of the NVV. Similar trends were observed in zeta-potential, surface energy, contact angle and antioxidant efficacy of the NVV, both with and without CU when UHPH was applied. The effect of Ultraviolet (UV) radiation (254 nm) on the stability of O/W nanoemulsion systems was investigated. A nano vesicular vehicle (NVV) was generated using ultra-high pressure homogenization (UHPH) that was stabilized using whey protein isolate (WPI) (1%, w/v), Tween 20 (20% w/w WPI) and casein hydrolysate (CH) (1:50 of WPI, w/w). Coarse emulsions were prepared by blending for three min. The coarse emulsion was exposed to UV radiation (0-60 min), followed by a single-pass of UHPH at 140 and 210 MPa. The UHPH treated NVV-CU had greater (P<0.05) short and long term antioxidant properties. After 28 d of storage, the CU-NVV treated at 210 MPa retained 7.0 and 1.4% greater AA and AP, respectively, when compared to the unpressurized CU-NVV.

The convergence of the digital and physical world encourages advances in high-speed telecommunication and fifth generation technology. Two-phase heat transfer systems are common engineering solutions. However, due to the large frequency spectra in 5G, the systematic heat generation increases requiring more efficient thermal management. The surface characteristics of solid materials in these systems is vital making micro-architectured materials a novel pathway to improve heat transfer. The coefficient of thermal expansion and thermal conductivity of the Schoen-Gyroid, a triply periodic minimal surface structure is studied along with a classical cylindrical porous structure. Graphite and graphene are considered as materials with excellent thermal and mechanical properties and are thus the base materials considered in this project. A comprehensive manufacturability study was conducted in order to gain knowledge regarding different graphite/graphene options and it was concluded that commercially available isotropic graphite was the best suited material for the purpose of this project. A decoupled thermo-mechanical analysis of the coefficient of thermal expansion and thermal conductivity of said structures as a function of volume fraction was conducted using computational homogenization with finite element analysis. A linearly elastic constitutive material model in COMSOL Multiphysics was used. As expected, the homogenized effective material is governed by linear constitutive model. Moreover, the results displayed a linear dependency on the porosity for both the CTE and thermal conductivity. The mechanical FEM model was validated using an analytical model derived by Gibson and Ashby and the thermal conductivity FEM model was validated using experimental data.

The application of lattice structures have become increasingly popular as additive manufacturing (AM) opens up the possibility to manufacture complex configurations. However, modelling such structures can be computationally expensive. The following thesis has been conducted in order for the department of Structural Analysis, at SAAB in Järfälla, to converge with the future use of AM and lattice structures. An approach to model lattice structures using homogenization is presented where three similar methods involving representative volume element (RVE) have been developed and evaluated. The stiffness matrices, of the RVEs, for different sizes of lattice structures, comprising of BCC strut-based units, have been obtained. The stiffness matrices were compared and analysed on a larger solid structure in order to see the deformational predictability of a lattice-based structure of the same size. The results showed that all methods were good approximations with slight differences in terms of boundary conditions (BCs) at the outer edge. The comparative analyses showed that two of the three methods matches the deformational predictability. The BCs in all methods have different influences which makes it pivotal to establish the BCs of the structure before using the approach presented in this thesis. / Ökad implementering av gitterstrukturer i komponenter är ett resultat av utvecklingen inom additiv tillverkning. Metoden öppnar upp för tillverkning av komplexa strukturer med färre delmoment. Dock så uppkommer det svårigheter vid simulering av dessa komplexa strukturer då beräkningar snabbt tyngs ner med ökad komplexitet. Följande examensarbete har utförts hos avdelningen Strukturanalys, på SAAB i Järfälla, för att de ska kunna möta upp det framtida behovet av beräkningar på additivt tillverkade gitterstrukturer. I det här arbetet presenteras ett tillvägagångsätt för modellering av gitterstrukturer med hjälp av represantiva volymselement. Styvhetsmatriser har räknats fram, för en vald gitterkonfiguration, som sedan viktats mot tre snarlika representativa volymselement. En jämförelseanalys mellan de olika styvhetsmatriserna har sedan gjorts på en större och solid modell för att se hur väl metoderna förutsett deformationen av en gitterstruktur i samma storlek. Resultaten har visat att samtliga metoder är bra approximationer med tämligen små skillnader från randeffekterna. Vid jämförelseanalysen simulerades gitterstrukturen bäst med två av de tre metoder. En av slutsatserna är att det är viktigt att förstå inverkan av randvillkoren hos gitterstrukturer innan implementering görs med det tillvägagångssätt som presenterats i det här examensarbetet.

The purpose of this study was to determine the impact of key process parameters on the flow properties of a novel High Protein Dairy Food (HPDF). HPDF was manufactured by an approach similar to that of manufacture of Halloumi cheese (a semi hard cheese originally from Cyprus). The effect of pasteurization condition, pH of acidification and homogenization were investigated on flowability, composition and texture of the HPDF. The study consisted of three different stages. After each stage of experimentation, the HPDF was analyzed for compositional, textural (by texture profile analysis) and flow properties during heating by microwave, oven and hot water was measured by Schreiber melt test. The first stage of experimentation screened 18 batches of HPDF under three levels of pasteurization conditions (191°F/16 sec, 175°F/16 sec and 161°F/16 sec), three levels of pH of acidification (5.8,6.2 and 6.6) and two levels of homogenization conditions (two stage homogenization (2000 psi/500 psi) and no homogenization). Based on the results of the first stage, a statistically powerful second stage of experiment was designed in which two levels of pasteurization condition (191°F/16 sec and 161°F/16 sec) and three levels of pH of acidification (5.8, 6.2 and 6.6) were employed in duplicate to manufacture HPDF. The third stage of experimental design was to investigate the effect of two-stage homogenization treatment (2000 psi/500 psi) with two levels (homogenization and no homogenization). The results of all three stages of experimentation proved that HPDF made from milk pasteurized under higher pasteurization condition (191°F/16 sec) had significantly higher flow resistance under all three heating conditions. There was significant interaction between pH of coagulation of milk and pasteurization condition on flow properties of HPDF with pH of coagulation 5.8 restriction flow of HPDF under all three heating conditions. The role of homogenization in restricting flow of HPDF was not significant, although the mean flow of HPDF, made from homogenized milk, decreased. The mean protein content and mean moisture content of HPDF was significantly affected by all three processing conditions, although the mean fat content of HPDF was not influenced by any of these conditions. The mean fat, protein and moisture content of HPDF were in the range of 10.5-11, 26-34 and 47-54 percent respectively. The primary textural properties affected significantly by the processing condition were hardness, chewiness and gumminess. Particularly, hardness was influenced by higher pasteurization condition and lower pH of acidification. Further, to judge the consumer acceptability of HPDF, various recipes made out of HPDF with different heating applications (baking, stir-frying and soup) were served to 12 panelists of DPTC. Their opinions were collected and analyzed statistically. The analysis of limited focus group survey showed that consumer liking for HPDF recipe was significantly influenced by prior familiarity with the recipe, although there was some preference for HPDF over tofu due to its ‘dairy’ flavor. When the texture of HPDF manufactured from milk pasteurized at 191°F/16 sec and pH of acidification 5.8 and 6.2 were compared with various commercial protein sources, the hardness of the HPDF was very close to extra firm tofu. All the other textural properties of HPDF were significantly different from firm, silken, baked or reduced fat tofu. From this project, it is evident that a high protein food, which can be part of day-to-day human diet and potential tofu alternative, can be obtained using halloumi approach by optimizing pasteurization condition (191°F/16 sec) and pH of coagulation (5.8).

Lightweight materials and structures are essential building blocks for a future with sustainable transportation and automotive industries. Incorporating lightweight materials and structures in today's vehicles, reduces weight and energy consumption while maintaining, or even improving, necessary mechanical properties and behaviors. Due to this, the environmental footprint can be reduced through the incorporation of lightweight structures and materials.  Awareness of the negative effects caused by pollution from emissions is ever increasing. Legislation, forced by authorities, drives industries to find better solutions with regard to the environmental impact. For the automotive industry, this implies more effective vehicles with respect to energy consumption. This can be achieved by introducing new, and improve current, methods of turning power into motion. An additional approach is reducing weight of the body in white (BIW) while maintaining crash worthiness to assure passenger safety. In addition to the structural integrity of the BIW, passenger safety is further increased through electrical systems integrated into the modern vehicle. Besides these safety systems, customers are also able to choose from a long list of gadgets to be fitted to the vehicle. As a result, the curb weight of vehicles are increasing, partly due to customer demands. In order to mitigate the increasing weights the BIW must be optimized with respect to weight, while maintaining its structural integrity and crash worthiness. To achieve this, new and innovative materials, geometries and structures are required, where the right material is used in the right place, resulting in a lightweight structure which can replace current configurations.  A variety of approaches are available for achieving lightweight, one of them being the press-hardening method, in which a heated blank is formed and quenched in the same process step. The result of the process is a component with greatly enhanced properties as compared to those of mild steel. Due to the properties of press hardened components they can be used to reduce the weight of the body-in-white. The process also allows for manufacturing of components with tailored properties, allowing the right material properties in the right place.  The present work aims to investigate, develop and in the end bring forth two types of light weight sandwiches; one intended for crash applications (Type I) and another for stiffness applications (Type II). Type I, based on press hardened boron steel, consists of a perforated core in between two face plates. To evaluate Type I's ability to absorb energy for crash applications a hat profile geometry is utilized. The hat profile is numerically subjected to loading from which the required energy to deform it can be found. These results are compared to those from a reference test, consisting of a hat profile based on solid steel and with an equivalent weight to that of the Type I hat profile. The aim is to minimize the weight of the core while maximizing the energy absorption. Type II consists of a bidirectional corrugated steel plate, placed in between two face plates. The geometry of the bidirectional core requires a large amount of finite elements for discretization causing a small time step and long simulation times. In order to reduce computational time a homogenization approach is suggested where the aim is to be able to predict stiffness of a planar sandwich at a reduced computational cost.  The numerical results from Type I show that it is possible to obtain a higher energy absorption per unit weight by introducing perforated cores in sandwich panels. Typically, energy absorption of such a panels were 20% higher as compared to a solid hat profile of equivalent weight, making it an attractive choice for reducing weight while maintaining performance. However, these results are awaiting experimental validation. The results from Type II show that it is possible, by introducing a homogenization procedure, to predict stiffness at a reduced computational cost. Validation by experiments were carried out as a sandwich panel was subjected to a three point bend in the laboratory. Numerical and experimental results agreed quite well, showing the possibilities of incorporating such panels into larger structure for stiffness applications.

As a perturbation method, averaging is a mathematical tool for dynamic analysis of time-periodic and space-periodic dynamical systems, including those governed by partial differential equations. The control design procedure presented in this work uses averaging techniques, the well-developed linear control strategies, and finite element methods. The controller is designed based on the linear averaged dynamics of a time- or space-periodic system. The controller is then used for trajectory tracking or stabilization of the periodic system. The applicability and performance of the suggested method depend on different physical parameters of the periodic system and the control parameters of the controller. The effects of these parameters are discussed in this work. Numerical simulations show acceptable performance of the proposed control design strategy for two linear and nonlinear time- and space-periodic systems, namely, the one-dimensional heat equation and the Chafee-Infante equation with periodic coefficients. / M.S. / Dynamic analysis and control of dynamical systems with varying parameters is a challenging task. It is always of great help if one can perform the analyses for an approximate system with constant parameters and use the results to study and control the original system with varying parameters. Averaging is a mathematical tool that is used to approximate a system with periodic parameters with a ``simpler'' system with constant parameters. In this research averaging is used for design of controllers for systems with periodic parameters. First, an approximate system with constant parameters, called the averaged system, is determined. The averaged system is used for design of a controller which can be then be used for the original system with periodic parameters.

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