Thesis (doctoral)--Universität Heidelberg, 1912. / Vita. "Chronologisches Register der im Separat-Abdruck erschienen en Werke Rods": p. 114.

Abhandlung--Zürich. / Lebenslauf. "Literaturverzeichnis": p. 95-98.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 393-404).

The U-curves of five different test objects, three of which contain a rod floating object at different positions within the gap, are characterised. During the testing, a high speed camera was used to photograph the discharges. The results are compared to Rizk’s theoretical model for determining the flashover voltage of gaps with floating objects are presented. It is concluded that the position of the floating object within the gap affects which discharge mechanism exists in each of the gaps. The effect that each discharge mechanism has on the flashover voltage and time to crest of the gap is shown. Time interval photographs are presented showing the formation of a discharge channel due to the streamer mechanism. In evaluating the high speed photographs it is seen that the extent of the branching of the discharge channel is a function of the time to crest of the applied impulse, more branching is evident for shorter times to crest.

No description available.

During operation of nuclear power reactors reactivity initiated accidents (RIA) can occur, such as a control rod drop. If this occurs, the reactivity increase dramatically and leads to an increase in power, fuel enthalpy and fuel temperature. The fuel and reactor can be damaged. A methodology to simulate these accidents has been developed for Forsmark Nuclear Power Plant in cooperation with Westinghouse, referred to as the POLCA7 methodology. The POLCA7 methodology results in a limit for fuel failure regarding reactivity of the control rod that dropped in pcm/control rod percent. The limit is estimated from simulations in POLCA7, a static and deterministic code and POLCA-T, a dynamic code. The aim of this thesis is to evaluate the methodology and investigate what happens in a reactor if a control rod drops during hot zero power. Hot zero power is a phase during start-up, where the power is low (~2% of installed power) and the reactor have operation pressure and temperature. The POLCA7 methodology was applied on historic cycles in Forsmark. To evaluate the POLCA7 methodology the control rod drop was simulated in S3K, a dynamic software. The results from these cycles indicate that the limit for fuel failure set in the POLCA7 methodology in pcm/control rod percent is very conservative for fuel with low and medium burnup. Even though the limit is exceeded, the dynamic simulation in S3K shows that the fuel is far from failure regarding SSM limits in fuel enthalpy and cladding temperature. In this thesis new limits in POLCA7 has been generated, which is remarkably higher than the original limit from the POLCA7 methodology. To challenge the methodology, an unrealistic fuel design was simulated with fuel with high burnup surrounded by high reactive fuel. With this fuel design, the enthalpy limit from SSM was exceeded for the fuel with high burnup. The limit from the POLCA7 methodology was exceeded which indicate that the POLCA7 methodology meets the goal of detecting severe RIAs. Fuel with high burnup seems to be the most important fuel to investigate at a RIA simulation. Another discovery is that POLCA7 gives the most severe accident at 2% power, but in S3K it is given by 3-4% power. This is a problem with the POLCA7 methodology. Suggestions are made on how to lower the calculation time and improve the methodology. A control rod sequence that gives an even power distribution and a core with the fuel with high burnup in the periphery and only a few fresh fuels is preferred to avoid damage at a RIA. A control rod sequence was designed for the new cycle in Forsmark 1, in order to try to create a cycle without problems due to RIA. The new sequence was a success with no control rods exceeding the limit of 82 pcm/control rod percent, and it shows that conclusions about the impact of the sequence are correct. Conclusion is made that the methodology should be further investigated and there are good chances to develop a good and time efficient analysis in the future. One presented suggestion is to have a dynamic simulation of the incident instead of the axial simulation. The evaluation with SSM’s limits would then be direct.

We consider one-dimensional longitudinal vibrations of a rigid rod with a nonuniform cross-section, fixed at its ends with lumped masses and springs. The cross-section inertia effects are taken into account on the basis of the Rayleigh theory. The equation of motion and the boundary conditions are derived from Hamilton’s variational principle. The characteristic equation is constructed and the eigenvalues for the harmonic vibrations of the rod are calculated. It is shown that the eigenvalues are bounded from above. Two types of the orthogonality of the eigenfunctions corresponding to the eigenvalues are discussed. The Green function is constructed for the problem of forced vibrations of the rod governed by a linear fourth-order partial differential equation, which involves mixed derivatives. Exact solutions of the rod vibration problems are found for rods with constant and conical cross-sections. Rigid isotropic waveguides are often used for generating, transmitting, and amplifying mechanical vibrations, for example, in acoustic transducers. Theoretical investigation of acoustic, mechanical, and electromagnetic waveguides is usually based on the analysis of second-order wave equations. This approach is justified in descriptions of the wave propagation in relatively thin and long rigid rods. As was shown by Rayleigh [1], the error due to the neglect of the transverse motion of the rod is proportional to the square of the ratio of the characteristic section radius to the length of the rod (aspect ratio). For a more accurate analysis of the longitudinal vibrations of a relatively thick and short rod, the rod deformation in the transverse direction must also be taken into account. The approach to the analysis of the vibrations of a thick and short rod used in this study is based on the theory of longitudinal vibrations of a rod, in which the effects due to the transverse motion are taken into account (the corresponding mathematical model is called the Rayleigh rod). The equation of motion and the boundary conditions for the onedimensional longitudinal vibrations of the Rayleigh rod with variable cross section and ends fixed by means of lumped masses and springs are derived from Hamilton’s variational principle. As a result, we arrive at a linear fourth-order partial differential equation with variable coefficients, which involves mixed derivatives. Previously, approximate analytical methods, such as the Galerkin method [2] and the method based on the expansion of the solution in a power series in the Poisson coefficient [3], were used for solving this equation. The frequencies of the natural vibrations of a cylindrical rod with rigidly fixed ends were determined in [4, pp. 159, 160]. In this study we use the method of the separation of variables based on the exact solutions of the equations of motion of the Rayleigh rod, which makes it possible to construct the Green function. A similar approach to an analysis of the longitudinal vibrations of stepped rigid waveguides described by second-order wave equations was applied in [5, 6].

No description available.

A description of the apparatus used in microwave phase and diffraction measurements is contained in the first chapter of this thesis. The field was investigated by a phase technique and the point source of radiation reasonably well established. Several diffraction patterns about a dielectric and a conducting rod were taken at several distances behind the rod with E vector of the field parallel to the axis of the rod. These were qualitatively analysed and compared with the patterns of one other worker at 1.25 cm. Agreements and differences were noted. / Thesis / Master of Science (MS)

BACKGROUND:Since their discovery, the morphology of microglia has been interpreted to mirror their function, with ramified microglia constantly surveying the micro-environment and rapidly activating when changes occur. In 1899, Franz Nissl discovered what we now recognize as a distinct microglial activation state, microglial rod cells (Stabchenzellen), which he observed adjacent to neurons. These rod-shaped microglia are typically found in human autopsy cases of paralysis of the insane, a disease of the pre-penicillin era, and best known today from HIV-1-infected brains. Microglial rod cells have been implicated in cortical 'synaptic stripping' but their exact role has remained unclear. This is due at least in part to a scarcity of experimental models. Now we have noted these rod microglia after experimental diffuse brain injury in brain regions that have an associated sensory sensitivity. Here, we describe the time course, location, and surrounding architecture associated with rod microglia following experimental diffuse traumatic brain injury (TBI).METHODS:Rats were subjected to a moderate midline fluid percussion injury (mFPI), which resulted in transient suppression of their righting reflex (6 to 10 min). Multiple immunohistochemistry protocols targeting microglia with Iba1 and other known microglia markers were undertaken to identify the morphological activation of microglia. Additionally, labeling with Iba1 and cell markers for neurons and astrocytes identified the architecture that surrounds these rod cells.RESULTS:We identified an abundance of Iba1-positive microglia with rod morphology in the primary sensory barrel fields (S1BF). Although present for at least 4 weeks post mFPI, they developed over the first week, peaking at 7 days post-injury. In the absence of contusion, Iba1-positive microglia appear to elongate with their processes extending from the apical and basal ends. These cells then abut one another and lay adjacent to cytoarchitecture of dendrites and axons, with no alignment with astrocytes and oligodendrocytes. Iba1-positive rod microglial cells differentially express other known markers for reactive microglia including OX-6 and CD68.CONCLUSION:Diffuse traumatic brain injury induces a distinct rod microglia morphology, unique phenotype, and novel association between cells / these observations entice further investigation for impact on neurological outcome.