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Lawrence Livermore National Laboratory's (LLNL) National Ignition Facility (NIF) uses a variety of diagnostics and image capturing optics for collecting data in High Energy Density Physics (HEDP) experiments. However, every image capturing system causes blurring and degradation of the images captured. This degradation can be mathematically described through a camera system's Point Spread Function (PSF), and can be reversed if the system's PSF is known. This is deconvolution, also called image restoration. Many PSFs can be determined experimentally by imaging a point source, which is a light emitting object that appears infinitesimally small to the camera. However, NIF's Kirkpatrick-Baez Optic (KBO) is more difficult to characterize because it has a spatially-varying PSF. Spatially varying PSFs make deconvolution much more difficult because instead of being 2-dimensional, a spatially varying PSF is 4-dimensional. This work discusses a method used for modeling the KBO's PSF by modeling it as the sum of products of two basis functions. This model assumes separability of the four dimensions of the PSF into two, 2-dimensional basis functions. While previous work would assume parametric forms for some of the basis functions, this work attempts to only use numeric representations of the basis functions. Previous work also ignores the possibility of non-linear magnification along each image axis, whereas this work successfully characterizes the KBO's non-linear magnification. Implementation of this model gives exceptional results, with the correlation coefficient between a model generated image and an experimental image as high as 0.9994. Modeling the PSF with high accuracy lays the groundwork to allow for deconvolution of images generated by the KBO.

The need for multiple access strategies arises whenever a number of users have to share a communication resource, since it is usually either cost prohibitive or impractical to dedicate a communication channel to a particular user. A need for such algorithms arises in many instances, particularly in applications utilizing wireless systems where all users access a common channel or medium. Such random access techniques as ALOHA and slotted ALOHA have been successfully implemented in a number of wireless applications. One of the major drawbacks of these algorithms is the necessity of a return path from the central station to each system user, which makes their use both inefficient and expensive for applications where one-way communication would suffice. For such applications, a need remained for a random access algorithm which can maximize the probability of successful message transmission in a one-way communication environment. A random access technique that addresses the above-mentioned need is developed. With this technique, each user sends an original message of predetermined length to a central receiver. The user then retransmits the message a specified number of times in a predetermined interval reserved for the retransmission process. The time interval between each successive retransmission of a given message is random. Assuming total annihilation of all colliding messages, the expression for the probability of successful transmission of a given message in terms of the major channel parameters is theoretically formulated. This technique offers a significant improvement, compared to a single transmission, in ensuring that a message is successfully received. The actual message collision dynamics in this system are experimentally studied using two different types of direct-sequence spread spectrum receivers, one employing a sliding correlator and the other using a matched filter. The spreading code in such systems offers extra protection for messages against possible interferers. The results indicate that it is often possible to properly receive a given message in the presence of co-channel interferers, thus significantly improving the overall system performance. These results are subsequently incorporated with the propagation data for several different types of microcells to arrive at a more precise theory of the link. / Ph. D.

Bakgrund: Enligt Friedmans (1970) klassiska teori ska ett företags primära mål vara att maximera aktieägarvärdet. Däremot rör vi oss nu mot hållbara finansiella marknader, vilket ställer krav på att företag inte enbart har aktieägare som huvudfokus, utan engagerar sig för alla intressenter. Detta väcker frågan om huruvida investerare värdesätter hållbara investeringar bortom faktorer som risk och avkastning, och om de är villiga att betala mer för en investering som gör nytta för samhället. Tidigare forskning har visat varierande resultat och denna studie upplever att det finns en brist på kunskap angående eventuell greenium på svenska obligationsmarknaden under verkliga marknadsförhållanden. Syfte: Syftet med studien var att undersöka och analysera om det existerade någon premie på gröna obligationer, även kallat greenium, gentemot konventionella obligationer. Studien undersökte vidare sambandet mellan spread och variablerna löptid, GII, kupongränta och YTM, samt deras påverkan på premien för gröna obligationer i Sverige. Metod: För att besvara studiens frågeställningar använde studien sig av en kvantitativ forskningsmetod med en deduktiv ansats. Studiens syfte uppfylldes genom en multipel linjär regression och en hypotesprövning på obligationer emitterade under perioden 2018-01-01 till 2023- 06-27. Resultat: Resultatet i studien visade att löptid, kupongränta och YTM hade en signifikant positiv effekt på spreaden, vilket innebär att dessa variabler påverkar prissättningen av obligationer. Däremot hade inte GII någon signifikant påverkan på spreaden, vilket innebär att om en obligation är grön eller konventionell inte verkade spela en avgörande roll i prissättningen. Vidare visade studien att det inte fanns tillräckligt med bevis för en statistiskt signifikant skillnad i spread mellan gröna obligationer och konventionella obligationer, vilket implicerade att greenium inte existerade.

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