Jet transport for General Linear methods

Estudiem la tècnica computacional anomenada “jet transport” per a la família d’integradors numèrics coneguts com a mètodes Generals Lineals (GLM), que generalitzen els reconeguts mètodes multipas lineals (LMM) i Runge–Kutta (RK). El jet transport ´es l’aplicació de l’aritmètica de sèries de potències truncades a un integrador numèric per tal d’obtenir la solució de les equacions variacionals (EV); és a dir, les equacions diferencials lineals que compleixen les derivades de la solució d’un problema de valor inicial (PVI). En particular, es discuteix la seva implementació i aplicacions

Jet transport for general linear methods

Treballs finals del Màster en Matemàtica Avançada, Facultat de Matemàtiques, Universitat de Barcelona: Curs: 2022-2023. Director: Àngel Jorba i Monte[en] The following project deals with two main topics: General Linear methods (GLM) and jet transport. For their presentation, we have divided it in three chapters. In Chapter 1, we introduce the family of numerical integrators known as General Linear methods, which arise as a natural generalization of the so-known linear multistep (LMM) and Runge-Kutta (RK) methods. Throughout the chapter, we present the main properties of LMM and RK methods so that they can be compared with those obtained for GLM with greater generality. In Chapter 2, we introduce the technique known as jet transport for the numerical integration of variational equations. It is in this chapter where the main contributuion of this project is found: we prove that the numerical integration of an initial value problem using jet transport with General Linear methods is equivalent to the numerical integration of their variational equations with the same method. Not only that, but we also successfully derive the expressions that the higher order coefficients of the jets must satisfy to be a solution of an implicit system, thus allowing the effective implementation of implicit General Linear methods. In Chapter 3 we conclude this project by studying how implicit Runge-Kutta methods can be efficiently implemented using jet transport and we apply this implementation to study a few scenarios in the field of dynamical systems, where the computation of variational equations is of interest

Career sidestep, wage setback? The impact of different types of career breaks on wages.

Research; Impact;

Loopbaanperspectieven op werk: wat we (niet) weten over loopbanen in Vlaanderen.

Vlaanderen;

Temporary employment and employability: training opportunities and efforts of temporary and permanent employees.

The rise of temporary employment contributes to the fact that people can no longer count on life time employment with one employer. The conclusion that life time employment within the same organisation is no longer a prerogative for all, inspires the search for new career concepts. 'Life time employability' is often put forward as an alternative to 'life time employment'. A successful career is, then, believed to be assured by having and obtaining the appropriate capacities for being continuously employable on the internal and external labour market during one's working life. At first sight, temporary employment relations and employability go hand in hand. For temporary employment is less dramatic when it is linked to a higher employability. The career opportunities of temporary workers are safeguarded by their employability. Opponents, however, add some critical observations to this statement and claim that contractual flexibility and employability enhancement are at odds. In this article, we deal with this question. If temporary employment and employability enhancing activities are at odds, temporary employees get less facilities to expand their employability. This can have important implications for the career opportunities of temps. We compare the employability enhancing activities of temporary and permanent employees. We study one central employability enhancing activity, namely training. Firstly, we have a look at the capacity and the willingness of temporary and permanent employees to participate in training in order to enhance their employability. Secondly, we also study the training opportunities that are offered by employers to temporary and permanent employees. The results indicate that, although temps do largely take responsibility for their own training, they get less opportunities to enhance their employability than permanent employeEmployment;

De opleidingscyclus.

Education and lifelong learning; Labour market; Onderwijs en levenslang leren; Arbeidsmarkt;

How HRM affects corporate financial performance: Evidence from Belgian SMEs.

In this paper, we provide a summary of several results from a study of HRM in small and medium-sized enterprises in Belgium. The central issue is whether the investment in HRM practices for smaller organizations is 'profitable'. This study differs in three ways from existing research. (1) It deals with the results from a survey of organizations with between 10 and 100 employees from various sectors. (2) In composing an index for 'HRM intensity', we started with a different interpretation of HRM practices, which also fits in more closely with the Belgian institutional context. (3) The operationalization of performance is based on a number of financial indicators which also help determine the 'state of health' of a company. Using the results of the survey, we examined the link between the score for HRM intensity, some performance outcomes and the financial performance of the organization using structural equation modeling. The results show that intensive HRM also offers added value for smaller organizations. Firstly, HRM intensification has a highly positive effect on productivity and, through productivity, reduces personnel costs/added value. This effect is sufficiently strong to compensate for the increased costs associated with intensive HRM. On top of this 'compensation effect', HRM intensity also has major effects on the profitability of the company.