These are the abstracts of the oral presentations of the 8th PhD conference held on 7 June 2024 in Freiberg.

This item contains the agenda, minutes, and attachments for the Faculty Senate meeting on this date. There may be additional materials from the meeting available at the Faculty Center.

This item contains the agenda, minutes, and attachments for the Faculty Senate meeting on this date. There may be additional materials from the meeting available at the Faculty Center.

The multi-target tracking problem essentially involves the recursive joint estimation of the state of unknown and time-varying number of targets present in a tracking scene, given a series of observations. This problem becomes more challenging because the sequence of observations is noisy and can become corrupted due to miss-detections and false alarms/clutter. Additionally, the detected observations are indistinguishable from clutter. Furthermore, whether the target(s) of interest are point or extended (in terms of spatial extent) poses even more technical challenges. An approach known as random finite sets provides an elegant and rigorous framework for the handling of the multi-target tracking problem. With a random finite sets formulation, both the multi-target states and multi-target observations are modelled as finite set valued random variables, that is, random variables which are random in both the number of elements and the values of the elements themselves. Furthermore, compared to other approaches, the random finite sets approach possesses a desirable characteristic of being free of explicit data association prior to tracking. In addition, a framework is available for dealing with random finite sets and is known as finite sets statistics. In this thesis, advanced signal processing techniques are employed to provide enhancements to and develop new random finite sets based multi-target tracking algorithms for the tracking of both point and extended targets with the aim to improve tracking performance in cluttered environments. To this end, firstly, a new and efficient Kalman-gain aided sequential Monte Carlo probability hypothesis density (KG-SMC-PHD) filter and a cardinalised particle probability hypothesis density (KG-SMC-CPHD) filter are proposed. These filters employ the Kalman- gain approach during weight update to correct predicted particle states by minimising the mean square error between the estimated measurement and the actual measurement received at a given time in order to arrive at a more accurate posterior. This technique identifies and selects those particles belonging to a particular target from a given PHD for state correction during weight computation. The proposed SMC-CPHD filter provides a better estimate of the number of targets. Besides the improved tracking accuracy, fewer particles are required in the proposed approach. Simulation results confirm the improved tracking performance when evaluated with different measures. Secondly, the KG-SMC-(C)PHD filters are particle filter (PF) based and as with PFs, they require a process known as resampling to avoid the problem of degeneracy. This thesis proposes a new resampling scheme to address a problem with the systematic resampling method which causes a high tendency of resampling very low weight particles especially when a large number of resampled particles are required; which in turn affect state estimation. Thirdly, the KG-SMC-(C)PHD filters proposed in this thesis perform filtering and not tracking , that is, they provide only point estimates of target states but do not provide connected estimates of target trajectories from one time step to the next. A new post processing step using game theory as a solution to this filtering - tracking problem is proposed. This approach was named the GTDA method. This method was employed in the KG-SMC-(C)PHD filter as a post processing technique and was evaluated using both simulated and real data obtained using the NI-USRP software defined radio platform in a passive bi-static radar system. Lastly, a new technique for the joint tracking and labelling of multiple extended targets is proposed. To achieve multiple extended target tracking using this technique, models for the target measurement rate, kinematic component and target extension are defined and jointly propagated in time under the generalised labelled multi-Bernoulli (GLMB) filter framework. The GLMB filter is a random finite sets-based filter. In particular, a Poisson mixture variational Bayesian (PMVB) model is developed to simultaneously estimate the measurement rate of multiple extended targets and extended target extension was modelled using B-splines. The proposed method was evaluated with various performance metrics in order to demonstrate its effectiveness in tracking multiple extended targets.

In this work, the structural, electronic, and optical properties of CdS nanoparticles with sizes up to 4nm have been calculated using density-functional theory (DFT). Inaccuracies in the description of the unoccupied states of the applied density-functional based tight-binding method (DFTB) are overcome by a new SCF-DFTB method. Density-functional-based calculations employing linear-response theory have been performed on cadmium sulfide nanoparticles considering different stoichiometries, underlying crystal structures (zincblende, wurtzite, rocksalt), particle shapes (spherical, cuboctahedral, tetrahedral), and saturations (unsaturated, partly saturated, completely saturated). For saturated particles, the calculated onset excitations are strong excitonic. The quantum-confinement effect in the lowest excitation is visible as the excitation energy decreases towards the bulk band gap with increasing particle size. Dangling bonds at unsaturated surface atoms introduce trapped surface states which lie below the lowest excitations of the completely saturated particles. The molecular orbitals (MOs), that are participating in the excitonic excitations, show the shape of the angular momenta of a hydrogen atom (s, p). Zincblende- and wurtzite-derived particles show very similar spectra, whereas the spectra of rocksalt-derived particles are rather featureless. Particle shapes that confine the orbital wavefunctions strongly (tetrahedron) give rise to less pronounced spectra with lower oscillator strengths. Finally, a very good agreement of the calculated data to experimentally available spectra and excitation energies is found.

Ph.d.-afhandling. Den kongelige Veterinær- og Landbohøjskole, 2002. / Haves også i trykt udg.

Dans les systèmes de perception multicapteurs, un point central concerne le suivi d'objets multiples. Dans mes travaux de thèse, le capteur principal est un télémètre laser à balayage qui perçoit des cibles étendues. Le problème desuivi multi-objets se décompose généralement en plusieurs étapes (détection, association et suivi) réalisées de manière séquentielle ou conjointe. Mes travaux ont permis de proposer des alternatives à ces méthodes en adoptant une approche "track-before-detect" sur cibles distribuées qui permet d'éviter la succession des traitements en proposant un cadre global de résolution de ce problème d'estimation. Dans une première partie, nous proposons une méthode de détection travaillant directement en coordonnées naturelles (polaires) qui exploite les propriétés d'invariance géométrique des objets suivis. Cette solution est ensuite intégrée dans le cadre des approches JPDA et PHD de suivi multicibles résolues grâce aux méthodes de Monte-Carlo séquentielles. La seconde partie du manuscrit vise à s'affranchir du détecteur pour proposer une méthode dans laquelle le modèle d'objet est directement intégré au processus de suivi. C'est sur ce point clé que les avancées ont été les plus significatives permettant d'aboutir à une méthode conjointe de détection et de suivi. Un processus d'agrégation a été développé afin de permettre une formalisation des données qui évite tout prétraitement sous-optimal. Nous avons finalement proposé un formalisme général pour les systèmes multicapteurs (multilidar, centrale inertielle, GPS). D'un point de vue applicatif, ces travaux ont été validés dans le domaine du suivi de véhicules pour les systèmes d'aide à la conduite.

El objetivo de esta tesis es predecir el rendimiento de los estudiantes de doctorado en la Universidad de Girona según características personales (background), actitudinales y de redes sociales de los estudiantes. La población estudiada son estudiantes de tercer y cuarto curso de doctorado y sus directores de tesis doctoral. Para obtener los datos se ha diseño un cuestionario web especificando sus ventajas y teniendo en cuenta algunos problemas tradicionales de no cobertura o no respuesta. El cuestionario web se hizo debido a la complejidad que comportan de las preguntas de red social. El cuestionario electrónico permite, mediante una serie de instrucciones, reducir el tiempo para responder y hacerlo menos cargado. Este cuestionario web, además es auto administrado, lo cual nos permite, según la literatura, unas respuestas mas honestas que cuestionario con encuestador.Se analiza la calidad de las preguntas de red social en cuestionario web para datos egocéntricos. Para eso se calcula la fiabilidad y la validez de este tipo de preguntas, por primera vez a través del modelo Multirasgo Multimétodo (Multitrait Multimethod). Al ser datos egocéntricos, se pueden considerar jerárquicos, y por primera vez se una un modelo Multirasgo Multimétodo Multinivel (multilevel Multitrait Multimethod). Las la fiabilidad y validez se pueden obtener a nivel individual (within group component) o a nivel de grupo (between group component) y se usan para llevar a cabo un meta-análisis con otras universidades europeas para analizar ciertas características de diseño del cuestionario. Estas características analizan si para preguntas de red social hechas en cuestionarios web son más fiables y validas hechas "by questions" o "by alters", si son presentes todas las etiquetas de frecuencia para los ítems o solo la del inicio y final, o si es mejor que el diseño del cuestionario esté en con color o blanco y negro.También se analiza la calidad de la red social en conjunto, en este caso específico son los grupos de investigación de la universidad. Se tratan los problemas de los datos ausentes en las redes completas. Se propone una nueva alternativa a la solución típica de la red egocéntrica o los respondientes proxies. Esta nueva alternativa la hemos nombrado "Nosduocentered Network" (red Nosduocentrada), se basa en dos actores centrales en una red. Estimando modelos de regresión, esta "Nosduocentered network" tiene mas poder predictivo para el rendimiento de los estudiantes de doctorado que la red egocéntrica.Además se corrigen las correlaciones de las variables actitudinales por atenuación debido al pequeño tamaño muestral. Finalmente, se hacen regresiones de los tres tipos de variables (background, actitudinales y de red social) y luego se combinan para analizar cual para predice mejor el rendimiento (según publicaciones académicas) de los estudiantes de doctorado. Los resultados nos llevan a predecir el rendimiento académico de los estudiantes de doctorado depende de variables personales (background) i actitudinales. Asimismo, se comparan los resultados obtenidos con otros estudios publicados. / The aim of this Doctoral Thesis is to predict the PhD students' academic performance in the University of Girona from characteristics of their research group understood as a social network and from background and attitudinal characteristics of the PhD student.The data collection was done through web survey, regarding the traditional problems related to coverage and response errors. Web survey was made in order to reduce the complexity of social network questions.The quality of social network questions for questionnaires with egocentered data is analyzed. For this, reliability and validity of this kind of questions are computed, for first time using a Multilevel Multitrait-Multimethod approach. Data are egocentered and thus hierarchy can be used. Reliability and validity can be obtained in an individual level (within group component) or group level (between group component), which are used for carrying out a meta analysis with other European universities. We study if social network questions asked in web questionnaires are more reliable and valid done "by questions" or "by alters", if the frequency labels are present or not and if the best questionnaire design is plane or graphical.Social network as a whole is also studied, in this case are the research groups in the University of Girona. There is a proposal for the missing data problem in complete networks, different from the egocentered network. This new network structure is called "Nosduocentered Network", which is based in two central actors in a network. Regression model estimations explain that this network has more predictive power in order to predict the academic performance for PhD students.Finally, regression models with background, attitudinal and social network variables are done. Then, we combine the regressions in order to specify the best combination which predicts the PhD student's performance (according to academic publications) best. According to the results, the academic performance depends on background and attitudinal variables. Also, a comparison of results from other published studies is done.

La poursuite multi-cibles a pour objet le suivi d’un ensemble de cibles mobiles à partir de données obtenues séquentiellement. Ce problème est particulièrement complexe du fait du nombre inconnu et variable de cibles, de la présence de bruit de mesure, de fausses alarmes, d’incertitude de détection et d’incertitude dans l’association de données. Les filtres PHD (Probability Hypothesis Density) constituent une nouvelle gamme de filtres adaptés à cette problématique. Ces techniques se distinguent des méthodes classiques (MHT, JPDAF, particulaire) par la modélisation de l’ensemble des cibles comme un ensemble fini aléatoire et par l’utilisation des moments de sa densité de probabilité. Dans la première partie, on s’intéresse principalement à la problématique de l’application des filtres PHD pour le filtrage multi-cibles maritime et aérien dans des scénarios réalistes et à l’étude des propriétés numériques de ces algorithmes. Dans la seconde partie, nous nous intéressons à l’étude théorique des processus de branchement liés aux équations du filtrage multi-cibles avec l’analyse des propriétés de stabilité et le comportement en temps long des semi-groupes d’intensités de branchements spatiaux. Ensuite, nous analysons les propriétés de stabilité exponentielle d’une classe d’équations à valeurs mesures que l’on rencontre dans le filtrage non-linéaire multi-cibles. Cette analyse s’applique notamment aux méthodes de type Monte Carlo séquentielles et aux algorithmes particulaires dans le cadre des filtres de Bernoulli et des filtres PHD. / The problem of multiple-object tracking consists in the recursive estimation ofthe state of several targets by using the information coming from an observation process. The objective of this thesis is to study the spatial branching processes andthe measure-valued systems arising in multi-object tracking. We focus on a class of filters called Probability Hypothesis Density (PHD) filters by first analyzing theirperformance on simulated scenarii and then by studying their properties of stabilityand convergence. The thesis is organized in two parts: the first part overviewsthe techniques proposed in the literature and introduces the Probability Hypothesis Density filter as a tractable approximation to the full multi-target Bayes filterbased on the Random Finite Sets formulation. A series of contributions concerning the numerical implementation of PHD filters are proposed as well as the analysis of their performance on realistic scenarios.The second part focuses on the theoretical aspects of the PHD recursion in the context of spatial branching processes. We establish the expression of the conditional distribution of a latent Poisson point process given an observation process and propose an alternative derivation of the PHD filter based on this result. Stability properties, long time behavior as well as the uniform convergence of a general class of stochastic filtering algorithms are discussed. Schemes to approximate the measure valued equations arising in nonlinear multi-target filtering are proposed and studied.

Thesis submitted in fulfilment of the requirements for the degree Doctor of Education in the Faculty of Education and Social Sciences at the Cape Peninsula University of Technology 2013 / Parental involvement in rural multigrade schools in South Africa is poor. This is mainly due to a lack of support for and insufficient knowledge regarding the development of a programme that would increase parental involvement at rural multigrade schools in South Africa. The context of multigrade education in South Africa reflects the reality of a lack of parental involvement. South African rural multigrade education is beset by a variety of internal and external challenges which have a detrimental effect on effective parental involvement. However, in the rural multigrade school context, parents have untapped potential that needs to be identified and acted upon in order to empower parents; this could provide the rural marginalised children with meaningful access to quality education. Research has proved that parental involvement has a positive effect on the quality of education. According to research, the six types of parental involvement are parenting, communicating, volunteering, learning at home, decision-making and collaborating with the community. In this study the focus was on involving parents in learning and allowing them to become active partners in education. To increase parental involvement in learning at rural multigrade schools in South Africa, an intervention was needed. This intervention came in the form of a school, community and family partnership programme. The core elements of a school, community and family partnership programme (SCAF partnership programme) were the creation of partnerships and communication channels between the school, community and family, as well as the utilisation of existing community resources. These core elements had a specific focus on learning. This study used Bourdieu's (1986) theory on capital and Epstein's (1995) theory of overlapping spheres of influence. The purpose of this study was to determine the characteristics of an effective school, community and family partnership programme that would increase parental involvement in learning at rural multigrade schools in South Africa. Design-based research was employed in order to design, develop and test the proposed programme. Research was conducted in two phases. During the preliminary phase, a needs and content analysis, review of literature, and the development of a conceptual or theoretical framework for the study were conducted. This was followed by a prototyping phase which is an iterative design phase consisting of iterations, each being a micro-cycle of research with formative evaluation as the most important research activity, and which is aimed at improving and refining the intervention. Summative evaluation was conducted during the prototype phase in order to determine whether the solution or intervention met the pre-determined specifications. Data gathered during this study indicated: 1. The SCAF partnership programme can increase parental involvement in learning at rural multigrade schools if certain product and process characteristics are active. 2. The SCAF partnership programme allows utilising school, home and community capital through interaction and collaboration to increase parental involvement in learning. 3. A SCAF partnership programme should focus on learning through creating partnerships and opportunities for communication, and utilising community resources. 4. A SCAF partnership programme should be employed through a specific process. 5. Design research offers an appropriate and powerful approach to design, develop and implement a SCAF partnership programme that increases parental involvement in learning at rural multigrade schools. Keywords: Parental involvement, Parents, Design Research, Rural multigrade schools, Rural multigrade education