263 research outputs found
Spectral Story Drift Demand Analysis for Building Structures During the 1999 Chi-Chi Taiwan Earthquake
No full text
Seismic performance evaluation of a 34-story steel building retrofitted with response modification elements
No full textCharacterization of the Escherichia coli ClpY (HslU) Substrate Recognition Site in ClpYQ (HslUV) Protease by the Yeast Two-Hybrid System
No full textSpin Caloritronic Phenomena Driven by Spin-orbit Coupling
No full textIn this thesis, we report several effects in spintronics and spin caloritronics related to relativistic spin-orbit coupling. In Chapter 2, we discuss the relativistic spin caloritronicHall effects in terms of a semiclassical theory for anomalous thermoelectric effects in ferromagnetic metals due to spin-orbit scattering at impurities, including the anomalous Nernst and Ettingshausen effect, the planar thermalHall effects, and thermolectric anisotropic magnetoresistance. The linear response relations between the currents and driving forces are derived for out-of-plane and in-plane magnetizations, respectively. In the out-of-plane configuration, there are anomalous thermoelectric Hall effects linear to the spin-orbit constant, while the thermoelectric anisotropic magnetoresistance and the planar Hall effect in the in-plane configuration are of second order in the spin-orbit coupling. The extrinsic theory systemizes the competing effects/mechanisms from a microscopic point of view and identifies the parameters needed to describe experiments. We developed a diffusion theory in Chapter 3 for the spin Hall magnetoresistance (SMR) in multilayers made from an insulating magnet F such as yttriumiron garnet (YIG), and a normal metal N with spin-orbit interactions, such as platinum (Pt). In an N|F bilayer system, the SMR requires spin-flip in N and spin-transfer at the N|F interface. Our results explain the SMR both qualitatively and quantitatively with transport parameters that are consistent with other experiments. The degrees of spin accumulation in N that can be controlled by the magnetization direction is found to be very significant. In the presence of an imaginary part of the spin-mixing conductance Gi we predicted an AHE-like signal (SHAHE), which has been observed experimentally and can be explained with values of Gi that agree with first principles calculations. We furthermore analyzed F|N|F spin valves for parallel and perpendicular magnetization configurations. The SMR torques under applied currents in N are expected to lead to magnetization dynamics of N|F and F|N|F structures. In Chapter 4,we generalized the SMR theory in Chapter 3 to a thin-film made of a metallic ferromagnet and take into account the out-of-plane spin currents generated by the spinHall effect, which were disregarded in Chapter 2. We predict a new contribution to the anisotropic magnetoresistance by the simultaneous action of the anomalous Hall effect and its inverse. By diffusion theory, we compare this contribution with the conventional anisotropic magnetoresistance, demonstrating that they can be distinguished experimentally by studying its dependence on the film thickness. The extra contribution to the magnetoresistance has a magnetization dependence different from that of the conventional AMR. While the conventional AMR is usually positive, the new contribution is always negative. In order to analyze the effect of interface and boundary roughness that was disregarded in Chapter 3, we reports in Chapter 5 a Boltzmann study to quantify how the surface/interface scattering affects the spin Hall physics. In a bilayer system made of N and FI, we observe an AHE-like transverse voltage induced by the spin dependent scattering at the FI|N interface, which is competing with the imaginary SMR predicted in Chapter 3. We further show that the spin diffusion equation on which the SMR in Chapter 3 is based, has to be corrected by the surface/interface roughness in the limit of thin-films. Our model provides an approach to analyze the role of roughness in recent measurements on layered systems. Even though the theories developed in Chapters 3–5 are not directly related to spin caloritronics, they can be easily generalized for their thermoelectric analogues by the formulation spelt out in Chapter 2, and can be useful for prospective research in spintronics and spin caloritronics.Quantum NanoscienceApplied Science
Study on Indoor Environment Evaluation and Reconstruction Strategy of Existing Public Buildings in Hot Summer and Cold Winter Zone
No full text
Design of an Underactuated Gripper for the Item Picking in Distribution Centers
No full textThe particular category of the underactuated grippers is chosen for the automation of the item picking in distribution centers. The underactuated grippers have fewer degrees of actuation than degrees of freedom, so they are mechanically simpler than the fully-actuated grippers, and they are able to adapt to objects regardless of their shapes. However, the existing underactuated grippers found in the literature are regarded overdesigned because more than enough passive elements are included. This paper is aimed to design and build a more simplified but still workable underactuated gripper for the item picking. The designed gripper contains a cable-pulley driven underactuated finger which has two phalanges, and an opposite fixed finger. Moreover, the fingertip of the underactuated finger is intended to move along the ground where the target object is laid. The dimensions of the gripper are selected in order to achieve the following two tasks: picking the cylindrical objects from the ground and retaining the grasp during a lifting transportation. The experiment setup fails to drive the fingertip of the underactuated finger moving along the ground, but it is shown that the designed gripper is still able to fulfill these two tasks, except for the case that when the initial spacing between the moving underactuated finger and the object is rather large.BMDBMechEMechanical, Maritime and Materials Engineerin
Back on track: Redeveloping the railway zone in Gouda
No full textA railway station is one of the most important elements of modern cities. The station is of vital importance to shops and other economic functions in the city centre because of the constant flow of people going in and out of the city. At present, many Dutch cities saw the necessity of redeveloping their railway station environments. Every railway station environment has an own identity, and therefore its own potentials. Analyzing the integration of railway stations within their city’s urban fabric is one of the ways to determine those potentials. Many current regeneration projects are only focused on the connectivity on a regional scale. Often the local accessibility is considered as less important. A lot has been written about the quality and liveability of public space already. The public space in the vicinity of a railway station is one of the most important public urban spaces in a city. It is the first space people experience when arriving in the city. However, in many current railway station environment redevelopment projects the liveability does not get priority. Many different factors have resulted in railway station environments that are unpleasant places to be, cut off from their surroundings. This is where the challenges lie for the nearby future in the Netherlands, to regain the importance of the railway station and the railway network, especially in a large metropolitan area like the Randstad. These two currently subordinated aspects; the spatial integration and the liveability of railway station environments will be emphasized in this MSc thesis. The project location of this thesis is the railway zone in Gouda. The spatial potential and the liveability of the current situation have been analyzed, as well as the changes the existing plans of the municipality of Gouda will make. As final product of this graduation project an alternative urban renewal plan has been developed for the railway zone in Gouda.Urban RegenerationUrbanismArchitectur
Onderzoek naar de langdurige wachttijden I/D scheepvaartweg naar Palembang middels computersimulatie
No full textIn de provincie Zuid-Sumatra in Indonesië ligt de havenstad Palembang. Voor deze provincie en zijn omgeving is het open blijven van de havens van essentieel belang. Deze havens zijn te bereiken via een 100 km. lange vaarweg over de Musi rivier. Door tal van ondiepten in de rivieren ontstaat grote wachttijd hetgeen een langdurige vaartijd betekend. Teneinde de problemen beter aan te pakken, worden 2 modellen ontwikkeld: Een Getijmodel en een SimulatiemodelHydraulic EngineeringCivil Engineering and Geoscience
- …
