Eine spezielle Art poröser Membranen sind die sogenannten Mikrosiebe. Ihre Dicke ist geringer als der Durchmesser der Poren und sie besitzen eine einheitliche Porengröße und eine dichte Porenpackung. Sie zeichnen sich somit durch eine hohe Trennschärfe aus und eignen sich daher und aufgrund ihres geringen Filtrationswiderstandes besonders für den Einsatz als Filtrationsmedien. Ein Prinzip, um Mikrosiebe herzustellen, ist die Partikel-assistierte Benetzung. Bei dieser Methode wird ein polymerisierbares organisches Öl zusammen mit Kieselgelpartikeln auf einer Wasseroberfläche gespreitet. Nach dem Auspolymerisieren des Öls und dem anschließenden Entfernen der Partikel erhält man die gewünschten Mikrosiebe, welche an den Stellen, an denen sich zuvor die Kieselgelpartikel befanden, Poren besitzen. Die Porengröße der Siebe ist dabei über die Größe der verwendeten Partikel in weiten Grenzen (ca. zwischen 20 nm und 1000 nm) einstellbar und die Größe und Form des Mikrosiebes wird lediglich durch die Flächengröße und -form der zur Herstellung verwendeten Wasseroberfläche vorgegeben. Jedoch ist die mechanische Stabilität der Mikrosiebe für die gewünschte Anwendung als Filtrationsmedium oftmals nicht zufriedenstellend. Daher ist eine Stabilisierung erforderlich. Eine Möglichkeit, diese Stabilisierung zu erreichen, ist das Aufbringen einer externen makroporösen Stützstruktur. Im Rahmen dieser Arbeit wird die Möglichkeit vorgestellt mittels der Drucktechnik des sog. Inkjet-Druckens eine potentielle Stützstruktur auf ein solches Mikrosieb zu applizieren und dieses somit zu stabilisieren.

Surface modification techniques have played important roles in various aspects of modern technology. They have been employed to improve substrates by altering surface physicochemical properties. An ideal surface modifying technique would be a method that is applicable to any kind of materials prepared from a wide range of polymers and that can occur under mild reaction conditions. The work in this thesis has utilized four main concepts: I) the development of a ‘grafting-from’ technique by covalently growing polymer grafts from particle surfaces, II) the presence of steric and electrosteric forces due to long-range repulsive interactions between particles, III) a combined surface grafting and layer-by-layer approach to create polyelectrolyte multilayers (PEMs) on particle surfaces to fabricate strong and functional materials, and IV) the roles of hydrophilic polymer grafts and substrate geometry on surface degradation. A non-destructive surface grafting technique was developed and applied to polylactide (PLA) particle surfaces. Their successful modification was verified by observed changes to the surface chemistry, morphology and topography of the particles. To quantify the aggregation behavior of grafted and non-grafted particles, force interaction measurements were performed using colloidal probe atomic force microscopy (AFM). Long-range repulsive interactions were observed when symmetric systems, i.e., hydrophilic polymer grafts on two interacting surfaces, and asymmetric system were applied. Electrosteric forces were observed when the symmetric substrates interacted at pH 7.4. When PEMs were alternately assembled on the surface of poly(L-lactide) (PLLA) particles, the grafted surfaces played a dominated role in altering the surface chemistry and morphology of the particles. Three-dimensional scaffolds of surface grafted particle coated with PEMs demonstrated high mechanical performance that agreed well with the mechanical performance of cancellous bone. Nanomaterials were used to functionalize the scaffolds and further influence their physicochemical properties. For example, when magnetic nanoparticles were used to functionalize the scaffolds, a high electrical conductivity was imparted, which is important for bone tissue regeneration. Furthermore, the stability of the surface grafted particles was evaluated in phosphate buffered saline (PBS) solution. The nature of the hydrophilic polymer grafts and the geometry of the PLLA substrates played central roles in altering the surface properties of films and particles. After 10 days of PBS immersion, larger alterations in the surface morphology were observed on the film compared with microparticles grafted with poly(acrylic acid) (PAA). In contrast to the PAA-grafted substrates, the morphology of poly(acrylamide) (PAAm)-grafted substrates was not affected by PBS immersion. Additionally, PAAm-grafted microparticulate substrates encountered surface degradation more rapidly than PAAm-grafted film substrates. / <p>QC 20151002</p>

No description available.

This dissertation develops a general framework for designing stabilizing feedback controllers and observers for dynamics with state/time dependent gains on the control signals and measured outputs. These gains have potential singularity periods but satisfy a technically non-trivial condition referred to as persistence of excitation. A persistence filter design constitutes the primary theoretical innovation of this work around which the controller and observer development is centered. Application areas of singular gain systems considered in this study include robotics, biomechanics, intelligent structures and spacecrafts. Several representative problems involving singular, time-dependent gains are addressed. The specific contributions of this dissertation are outlined as follows: (i) a stabilizing feedback for linear, single-input systems with time-varying, singular control scaling is designed that allows arbitrary exponential convergence rate for the closed-loop dynamics. An adaptive control generalization of this result allows asymptotic convergence in presence of unknown plant parameters. An extension to a special, single-input nonlinear system in the controller canonical form is also proposed. It is proven that this control design results in bounded tracking error signals for a trajectory tracking objective; (ii) observer design for linear, single-output systems with time-varying, singular measurement gains is considered. A persistence filter similar in structure to the control counterpart aids an observer design that guarantees exponential state reconstruction with arbitrary convergence rates; (iii) the observer and controller designs are combined to obtain an exponentially stabilizing output feedback controller for linear, single-input, single-output dynamics with singular gains on both the control and measurements. A novel separation property is established as a consequence. The construction motivates applications to stabilization with reversible transducers which can switch between sensor and actuator modes. The results are verified on two illustrative applications, vibration control using piezoelectric devices and inverted pendulum stabilization with a DC motor. The linear result is further generalized to include state dependent gains; (iv) application of the persistence filter theory to spacecraft attitude stabilization using intermittent actuation is explored. The intermittence is characterized by a time-varying, periodically singular control gain. A nonlinear persistence filter allows construction of an exponentially stabilizing controller and simulations verify convergence with intermittent actuation where conventional proportional-derivative control fails; (v) a stabilization result for a special multi-input, linear system with time-varying matrix control gains is presented. The matrix gain is assumed to be diagonal but allows fewer controls than states subject to a controllability assumption in absence of the singular gain matrix. The single-input adaptive control results are shown to extend to the multi-input case. An application to angular velocity stabilization of an underactuated rigid spacecraft is considered. / text

中共隨經濟的高度發展對能源的消耗也愈來愈高，其能源產量除了煤炭之外，其他如石油、天然氣等石化燃料都面臨不足，已經無法靠自有石油資源來因應高消耗量，也造成日漸依賴進口的能源，而其能源進口地區主要是在中東，但是中東地區政局不穩定，且這條海上運輸線需經過索馬利亞和亞丁灣，沿線海盜猖獗，麻六甲的航道又比較狹長，若航運通道遭受阻斷，將足以對中共能源供應穩定帶來衝擊。 而中共於2009年12月啟動了第一條跨國天然氣管道—中亞天然氣管道(閥門)，該管道西起土庫曼穿越烏茲別克中部和哈薩克南部地區，經新疆霍爾果斯口岸入境;這等於打通了中共和中亞地區各國的進口原油的通道。截至2014年4月中旬，從新疆霍爾果斯口岸入境的中亞天然氣管道，已累計向中共輸送天然氣達到500億立方米。 然而新疆維吾爾自治區位於中共西北部地處，自古以來就是中共向西開放的重要門戶，有長達5,600公里的邊境線，惟新疆少數民族乃未停息的宗教不安問題，一直是北京及中亞最可能的潛在引爆點。為維持中共新疆地區社會穩定、經濟健康發展、民族團結、邊防鞏固及維護和保持新疆社會大局穩定，因此中共對新疆境內分離份子的態度（新疆境內有42﹪維吾爾族人），自然是中共關切所在。因此中共於新疆地區執行各項維穩及反恐任務，來抑制少數伊斯蘭教激進份子的東突厥斯坦獨立運動思潮，來達到其穩定內部社會秩序、並藉由與國際間的反恐合作持續在反恐建設上加強作為，鞏固政權及確保經由陸路運輸的石油氣管道安全，是當前對新疆最重要及緊迫的任務;其發展對中共的能源安全戰略、擴大與中亞、南亞的能源合作、保持邊疆穩定具有十分重要價值，使得新疆作為中共石油資源戰略接替區的戰略地位更加明朗。 / While energy consumption rises significantly with the rapid economic growth, China becomes self-insufficient in all kinds of fossil fuel, such as oil and natural gas, except coal, and depends more and more on imported resources, accordingly. China exports its energy resources from the Middle East mostly, however, stable supply from this area cannot be promised. First of all, many oil-producing countries in the Middle East suffer from regime transitions; secondly, the problem of pirate in the offshore Somalia and the Gulf of Aden cannot be overcome, and it would be highly inconvenient if the sea lines through the Strait of Malacca were interrupted. Therefore, China began to construct the first gas interstate pipeline in Central Asia, which starts from Turkmenistan, central Uzbekistan, southern Kazakhstan, and enters China through the border city in Xinjian Uyghur Autonomous region, Horgos. Until mid-April 2014, this pipeline has delivered 50 billion cbm natural from Central Asia to China. However, this region, located in the Northwest China with 5,600 borderline, has been a disturbing issue for China because of conflict among ethnic and religious minorities and Chinese people. In order to maintain the stability in the economy, society and diverse ethnics in the border, China practices several policies, such as stabilization and counter-terrorism, to suppress the independence activity by Islamic extremists in Uyghuristan. Additionally, is important for China to secure the pipeline through Central Asia and the local governance by counter-terrorism with international cooperation. Therefore, Xinjian has strategic value for China regarding energy security, not just for the resource access to Central Asia, but also for the cooperation in South Asia. Central Asia, energy security, land pipeline, stabilization in Xinjian

Nature and its variety of motion forms have inspired new robot designs with inherentunderactuated dynamics. The fundamental characteristic of these controlled mechanicalsystems, called underactuated, is to have the number of actuators less than the number ofdegrees of freedom. The absence of full actuation brings challenges to planning feasibletrajectories and designing controllers. This is in contrast to classical fully-actuated robots.A particular problem that arises upon study of such systems is that of generating periodicmotions, which can be seen in various natural actions such as walking, running,hopping, dribbling a ball, etc. It is assumed that dynamics can be modeled by a classicalset of second-order nonlinear differential equations with impulse effects describing possibleinstantaneous impacts, such as the collision of the foot with the ground at heel strikein a walking gait. Hence, we arrive at creating periodic solutions in underactuated Euler-Lagrange systems with or without impulse effects. However, in the qualitative theory ofnonlinear dynamical systems, the problem of verifying existence of periodic trajectoriesis a rather nontrivial subject.The aim of this work is to propose systematic procedures to plan such motions and ananalytical technique to design orbitally stabilizing feedback controllers. We analyze andexemplify both cases, when the robotmodel is described just by continuous dynamics, andwhen continuous dynamics is interrupted from time to time by state-dependent updates.For trajectory planning, systems with one or two passive links are considered, forwhich conditions are derived to achieve periodicmotions by encoding synchronizedmovementsof all the degrees of freedom. For controller design we use an explicit form tolinearize dynamics transverse to the motion. This computation is valid for an arbitrarydegree of under-actuation. The linear system obtained, called transverse linearization, isused to analyze local properties in a vicinity of the motion, and also to design feedbackcontrollers. The theoretical background of these methods is presented, and developedin detail for some particular examples. They include the generation of oscillations forinverted pendulums, the analysis of human movements by captured motion data, and asystematic gait synthesis approach for a three-link biped walker with one actuator.

This doctoral thesis addresses questions of how wind loads acting on multistoreytimber buildings can be dealt with by structural design of such buildings.The conventional use of sheathing either nailed or screwed to a timberframework is considered, together with other stabilizing structures such ascross-laminated timber panels.The finite element method was employed in simulating the structuralbehaviour of stabilizing wall units. A series of studies was carried out of walls inwhich the sheathing was nailed to a timber frame. Different structural levelswere studied starting with modelling the performance of single sheathing-toframingconnections, to the use of models for studying the overall structuralbehaviour of walls. The results of calculations using models for simulation ofwalls subjected to different loading agree reasonably well with experimentalresults. The structural properties of the connections between the sheathing andthe frame, as well as of the connections between the members of the frame,were shown to have a substantial effect on the simulated behaviour of shearwall units. Both these types of connections were studied and described inappended papers.Regarding cross-laminated timber wall panels, it was concluded that walls witha high level of both stiffness and strength can be produced by the use of suchpanels, and also that the connections between the solid wall panels can bedesigned in such a way that the shear forces involved are transmitted from onepanel to the next in an efficient manner.Other topics in the thesis include the properties of connections between shearwalls and the rest of the building. Typically high tension forces occur at specificpoints in a timber structure. These forces need to be transmitted downwards inthe structure, ultimately connecting them to the substrate. A lap-joint that maybe used for this purpose has been studied using generalized Volkersen theory.Finally the maximum capacity of a conventional rail to substrate connection hasbeen examined using linear and nonlinear fracture mechanics.

Ultracold atoms provide a powerful tool for studying quantum control of interacting many-body systems with well-characterized and controllable Hamiltonians. In this thesis, we demonstrate quantum control of a many-body system consisting of a ferromagnetic spin-1 Bose-Einstein condensate (BEC). By tuning the Hamiltonian of the system, we can generate either a phase space with an unstable hyperbolic fixed point or a phase space with an elliptical fixed point. A classical pendulum with a stable oscillation about the "down" position and an inverted pendulum with unstable non-equilibrium dynamics about the "up" position are classical analogs of the quantum spin dynamics we investigate in this thesis. In one experiment, we dynamically stabilize the system about an unstable hyperbolic fixed point, which is similar to stabilizing an inverted pendulum. In a second experiment, we parametrically excite the system by modulating the quadratic Zeeman energy. In addition, we demonstrate rectifier phase control as a new method to manipulate the quantum states of the many-body system. This is similar to parametric excitation and manipulation of the oscillation angle of a classical pendulum. These experiments demonstrate the ability to control a quantum system realized in a spinor BEC, and they also can be applied to other quantum systems. In addition, we extend our studies to atoms above the Bose-Einstein transition temperature, and we present results on thermal spin relaxation processes and equilibrium spin populations.

Disertacijoje nagrinėjama pacientų, dėl didelės energijos bukos traumos patyrusių dauginius kūno sužalojimus, kojų ilgųjų kaulų lūžių gydymo įtaka mirčiai. Ištirtas ir su tarptautiniu standartu palygintas pacientų su dauginiais kūno sužalojimais būklės vertinimas ir gaivinimas ikihospitaliniu laikotarpiu. Įvertintas asmenų, patyrusių dauginius kūno sužalojimus, sužalojimų pobūdis, sunkumas, komplikacijos ir baigtis. Įvertinti dauginių kūno sužalojimų gydymo rezultatai, atsižvelgiant į operacinį ar konservatyvų kojų ilgųjų kaulų lūžių gydymą suvienodintose pagal amžių ir sužalojimo sunkumą pacientų grupėse. Nustatyti veiksniai, turintys ���taką pacientų su dauginiais kūno sužalojimais mirčiai. / Influence of lower extremity long bone fracture treatment of severe polytrauma patients after high energy blunt trauma is evaluated. Pre-hospital initial assessment and management of patients with multiple injuries is estimated and compared with the international standard. The nature, injury severity, complications and the outcome of the patients who suffered multiple injuries are evaluated. The treatment results of multiple injuries taking into account lower extremity long bone fractures operative or conservative treatment in pair matching groups of patients are evaluated. The factors that has impact on mortality of the polytrauma patients are determinated.

This study presents different aspects on the use of deterministic methods including Artificial Neural Networks (ANNs), and linear and nonlinear regression, as well as probabilistic methods including Bayesian inference and Monte Carlo methods to develop reliable solutions for challenging problems in geotechnics. This study addresses the theoretical and computational advantages and limitations of these methods in application to: 1) prediction of the stiffness and strength of stabilized organic soils, 2) determination of unknown foundations for bridges vulnerable to scour, and 3) uncertainty quantification for one-dimensional diffusion processes. ANNs were successfully implemented in this study to develop nonlinear models for the mechanical properties of stabilized organic soils. ANN models were able to learn from the training examples and then generalize the trend to make predictions for the stiffness and strength of stabilized organic soils. A stepwise parameter selection and a sensitivity analysis method were implemented to identify the most relevant factors for the prediction of the stiffness and strength. Also, the variations of the stiffness and strength with respect to each factor were investigated. A deterministic and a probabilistic approach were proposed to evaluate the characteristics of unknown foundations of bridges subjected to scour. The proposed methods were successfully implemented and validated by collecting data for bridges in the Bryan District. ANN models were developed and trained using the database of bridges to predict the foundation type and embedment depth. The probabilistic Bayesian approach generated probability distributions for the foundation and soil characteristics and was able to capture the uncertainty in the predictions. The parametric and numerical uncertainties in the one-dimensional diffusion process were evaluated under varying observation conditions. The inverse problem was solved using Bayesian inference formulated by both the analytical and numerical solutions of the ordinary differential equation of diffusion. The numerical uncertainty was evaluated by comparing the mean and standard deviation of the posterior realizations of the process corresponding to the analytical and numerical solutions of the forward problem. It was shown that higher correlation in the structure of the observations increased both parametric and numerical uncertainties, whereas increasing the number of data dramatically decreased the uncertainties in the diffusion process.