Perfect partial reconstructions for multiple simultaneous sources

A major focus of research in the seismic industry of the past two decades has been the acquisition and subsequent separation of seismic data using multiple sources fired simultaneously. The recently introduced method of {\it signal apparition} provides a new take on the problem by replacing the random time-shifts usually employed to encode the different sources by fully deterministic periodic time-shifts. In this paper we give a mathematical proof showing that the signal apparition method results in optimally large regions in the frequency-wavenumber space where exact separation of sources is achieved. These regions are diamond-shaped and we prove that using any other method of source encoding results in strictly smaller regions of exact separation. The results are valid for arbitrary number of sources. Numerical examples for different number of sources (three resp.~four sources) demonstrate the exact recovery of these diamond-shaped regions. The theoretical proofs' implementation in the field is illustrated by the results of a conducted field test.Comment: 16 pages, 5 figures. Expanded Section 3 with an additional numerical experiment and the results of a field test. Added reference

OPERATION OF V.L.C.C.'S IN HEAVY WEATHER

A short review is presented of available instrumentation systems designed to assist the operation of ships in heavy weather by warning against dangerous wave loads. Some systems also give guidance to the master by predicting the outcome of evasive actions, and the bases on which such predictions are made, such as visual observations of the wave system, are questioned. A method is presented in which the motions of the ship are used to determine the sea state in the form of an "equivalent" wave spectrum. Two investigations of the possibility of improving the guidance capability of warning instruments are described, in which the predictions are based on the equivalent wave spectrum. For this purpose, recorded full-scale data from a container ship and a tanker have been analysed and the two methods, spectrum analysis and a statistical method, are described. Using the equivalent spectrum, predictions of the effect of a change of course and estimates of one response from another have been made and compared to measured values. The results of these comparisons, which are presented graphically and in the form of correlations between measured and predicted values, are discussed with respect to error sources and factors which limit the method's applicability. The accuracy in predicting one response from another was found to be higher the closer the correlation between the responses, and correct estimations of the relative heading and the angular energy distribution of the wave system were found to be of importance. Theoretical calculations of ship responses to irregular waves have been made by linear superposition of transfer functions and wave spectra and a new way of extrapolating the transfer functions is described

Direct Evidence of Dividend Tax Clienteles

We study a large data set of stock portfolios held by individuals and organizations in the Swedish stock market. The dividend yields on these port-folios are systematically related to investors' relative tax preferences for dividends versus capital gains. Tax-neutral investors earn 40 basis points higher dividend yield on their portfolios than investors which face higher effective taxation of dividends than capital gains. We conclude that there are dividend tax clienteles in the market. We also argue that the abundant portfolio holdings by private corporations, despite triple taxation at a combined marginal tax rate as high as 77.5%, is a consequence of taxation.Tax incidence; dividend tax clienteles; capital gains tax; stock ownership

Hästens behov av vitamin A, D och E i foderstaten

Vitaminer är essentiella komponenter som medverkar i olika processer i kroppen. Hästens vitaminbehov beror på ålder, träning, laktation, dräktighet och tillväxt. Underkott av ett vitamin kan resultera i olika bristsjukdomar, vilka kan vara dödliga. Idag marknadsförs dyra vitaminkoncentrat som ett komplement till den befintliga vitaminhalten i foderstaten. Innan utfodring av dessa koncentrat är det viktigt att veta om hästen har ett behov av vitaminkoncentrat eller om de leder till överutfodring. Ett grovfoders vitaminbehov kan påverkas genom vilken vallinbladning som används då vissa gräsarter och baljväxter är mer vitaminrika än andra. Ensilage har bevisats bevara halten vitamin A och E bättre än hö, men däremot innehåller hö en högre halt vitamin D. Försök har påvisat att plasmanivåer av vitamin A, D och E är säsongsvarierande med lägre halt under vinterhalvåret, därmed är tillskottsutfodring av vitaminkoncentrat mer relevant under vinterhalvåret. Denna kandidatuppsats undersöker olika funktioner hos vitamin A, D och E och dess förekomst i grovfoder. Rekommendationer angående hästens vitaminbehov har sammanställts och diskuterats utifrån dess trovärdighet och huruvida ett vitamintillskott är nödvändigt.Vitamin A, D and E are essential components in the body and contribute in many biochemical and metabolic reactions. The horse’s need of vitamins depend on several factors such as: age, level of exercise, lactation, gestation and growth. Shortage of a certain vitamin could cause several deficiency diseases. Today there are several vitamin supplements available at the market promising their product to be the best one for the horse. But before this supplements are fed to the horse it is important to know if the horse really requires a supplement of vitamins or if there is a risk of overfeeding to toxic levels. Forage vitamin content could be influenced by different factors, such as which species of plants the forages contains. For example, leguminous plant contents more vitamins than different grasses. It has been proved that silage contains a higher level of caroteniod and tocopherol than hay, but hay contains a higher level of ergosterol, the provitamin of vitamin D2. Different levels of vitamin A, D and E has been detected in plasma during different seasons, where the levels in plasma were higher during the summer than in the winter. This bachelor thesis review different functions in vitamin A, D and E and their occurrence in forage. Available feeding recommendations concerning a horse need of vitamin A, D and E have been put together in purpose to discuss if a supplement of a vitamin supplement is needed in the feeding plan

Continuum modeling of paperboard for the mechanical response of converting processes

Paperboard is a thin and lightweight material made of cellulose fibers and it is an important component in packaging material where it provides stiffness and rigidity. The scope of this work is the development of continuum models, and its numerical treatments, for simulating the processes of converting paperboard into packages. The thesis begins with a general introduction to paperboard and a review of modeling approaches are presented. Important continuum modeling concepts used in the papers are presented and key paperboard converting processes are discussed. The main part of the thesis consists of four papers denoted A, B, C and D and they are briefly outlined below.To reduce the computational effort during large scale paperboard forming simulations, a numerical technique which combines a state-of-the-art continuum model for paperboard with state-of-the-art finite element modeling is investigated in Paper A. The model is built up by solid-shell elements where the thickness direction is naturally included in the framework such that the out-of-plane response can be modeled. The approach is validated by numerical studies where the results are compared against fully integrated brick elements. Furthermore, a large-scale forming example for paperboard is explored. Since the loading rate varies during industrial processes and the aim is to maximize the operational velocity, a rate-dependent continuum model for paperboard is developed in Paper B. The new rate-dependent model is based on the static material model in Paper A which is enhanced with a viscoelastic and viscoplastic framework. The developed model is calibrated using uniaxial experiments and evaluated against line-creasing and line-folding measurements. In Paper C, the continuum model in Paper A is enhanced to include continuum damage. Damage is needed to adequately capture the mechanical response during sequential loading of creasing and folding. A scalar isotropic damage variable is introduced and the damage evolution is calibrated for a reference mesh during folding. A simple scaling strategy is introduced to reduce the mesh dependence due to damage evolution. To showcase the proposed model, an illustrative $3$D example is presented where a paperboard sheet is creased and folded to mimic the corner folding process. In Paper D, an experimental device and a protocol is developed for cyclic uniaxial out-of-plane compression and tension measurements. This load case is important since it is present during creasing and subsequent folding where the material is subject to large out-of-plane compressive stresses followed by out-of-plane tension and delamination. The soft initial load-displacement response during compression is shown to stem from the surface roughness and not a material property. In addition, the experiments show that the transition from compression to tension is smooth. Consequently, a switch function, previously introduced in literature that separates the elastic behavior between compression and tension, is deemed as questionable for continuum modeling

On Observer-Based Control of Nonlinear Systems

Filtering and reconstruction of signals play a fundamental role in modern signal processing, telecommunications, and control theory and are used in numerous applications. The feedback principle is an important concept in control theory. Many different control strategies are based on the assumption that all internal states of the control object are available for feedback. In most cases, however, only a few of the states or some functions of the states can be measured. This circumstance raises the need for techniques, which makes it possible not only to estimate states, but also to derive control laws that guarantee stability when using the estimated states instead of the true ones. For linear systems, the separation principle assures stability for the use of converging state estimates in a stabilizing state feedback control law. In general, however, the combination of separately designed state observers and state feedback controllers does not preserve performance, robustness, or even stability of each of the separate designs. In this thesis, the problems of observer design and observer-based control for nonlinear systems are addressed. The deterministic continuous-time systems have been in focus. Stability analysis related to the Positive Real Lemma with relevance for output feedback control is presented. Separation results for a class of nonholonomic nonlinear systems, where the combination of independently designed observers and state-feedback controllers assures stability in the output tracking problem are shown. In addition, a generalization to the observer-backstepping method where the controller is designed with respect to estimated states, taking into account the effects of the estimation errors, is presented. Velocity observers with application to ship dynamics and mechanical manipulators are also presented