Study on the valorization routes of ashes from thermoelectric power plants working under mono-and co-combustion regimes

Thesis submitted to obtain the Doctoral degree in Energy and Bioenergy

Cellulose-based composites as functional conductive materials for printed electronics

In this work, cellulose-based electro and ionic conductive composites were developed for application in cellulose based printed electronics. Electroconductive inks were successfully formulated for screen-printing using carbon fibers (CFs) and multi-walled carbon nanotubes (MWCNTs) as conductive functional material and cellulose derivatives working as binder. The formulated inks were used to fabricate conductive flexible and disposable electrodes on paper-based substrates. Interesting results were obtained after 10 printing passes and drying at RT of the ink with 10 % wt. of pristine CFs and 3% wt. of carboxymethyl cellulose (CMC), exhibiting a resistivity of 1.03 Ωcm and a resolution of 400 μm. Also, a resistivity of 0.57 Ωcm was obtained for only one printing pass using an ink based on 0.5 % wt. MWCNTs and 3 % wt. CMC. It was also demonstrated that ionic conductive cellulose matrix hydrogel can be used in electrolyte-gated transistors (EGTs). The electrolytes revealed a double layer capacitance of 12.10 μFcm-2 and ionic conductivity of 3.56x10-7 Scm-1. EGTs with a planar configuration, using sputtered GIZO as semiconducting layer, reached an ON/OFF ratio of 3.47x105, a VON of 0.2 V and a charge carrier mobility of 2.32 cm2V-1s-1.

Working in IT projects – Options and Limits of Work Design

Flexible forms of work like project work are gaining importance in industry and services. Looking at the research on project work, the vast majority of present literature is on project management, but increasingly, problems concerning the quality of work and the efficiency of project teams become visible. The question now is how project work can be structured in order to simultaneously provide efficient and flexible work and healthy working conditions ensuring the development of human resources for a long time. Selected results of publicly funded research into project work will be presented based on case studies in 7 software development /IT consulting project teams (N=34). A set of different methods was applied: interviews with management/project managers, group interviews on work constraints, a monthly diary about well-being and critical incidences in the course of the project, and a final evaluation questionnaire on project outcomes focusing on economic and health aspects. Findings reveal that different types of projects exist with varying degree of team members’ autonomy and influence on work structuring. An effect of self-regulation on mental strain could not be found. The results emphasize, that contradicting requirements and insufficient organizational resources with respect to the work requirements lead to an increased work intensity or work obstruction. These contradicting requirements are identified as main drivers for generating stress. Finally, employees with high values on stress for more than 2 months have significantly higher exhaustion rates than those with only one month peaks. Structuring project work and taking into account the dynamics of project work, there is a need for an active role of the project team in contract negotiation or the detailed definition of work – this is not only a question of individual autonomy but of negotiation the range of option for work structuring. Therefore, along with the sequential definition of the (software) product, the working conditions need to be re-defined.

Influence of constraining and confinement in the molecular mobility of low molecular weight materials

Dissertation presented to obtain a Ph.D. Degree in Chemical Physics

Design of New Materials for Passive Vibration Control

The objective of this contribution is to extend the models of cellular/composite material design to nonlinear material behaviour and apply them for design of materials for passive vibration control. As a first step a computational tool allowing determination of optimised one-dimensional isolator behaviour was developed. This model can serve as a representation for idealised macroscopic behaviour. Optimal isolator behaviour to a given set of loads is obtained by generic probabilistic metaalgorithm, simulated annealing. Cost functional involves minimization of maximum response amplitude in a set of predefined time intervals and maximization of total energy absorbed in the first loop. Dependence of the global optimum on several combinations of leading parameters of the simulated annealing procedure, like neighbourhood definition and annealing schedule, is also studied and analyzed. Obtained results facilitate the design of elastomeric cellular materials with improved behaviour in terms of dynamic stiffness for passive vibration control.

Preliminary study on the production of functionally graded materials by friction stir processing

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Mecânica

Improving writing through creativity

Trabalho de Projecto apresentado para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Ensino do Inglês

Study of materials, technique and conservation treatment of Sinfonia Heroica by Dordio Gomes

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Conservação e Restauro

Design of New Materials for Passive Vibration Control

The aim of this contribution is to extend the techniques of composite materials design to non-linear material behaviour and apply it for design of new materials for passive vibration control. As a first step a computational tool allowing determination of macroscopic optimized one-dimensional isolator behaviour was developed. Voigt, Maxwell, standard and more complex material models can be implemented. Objective function considers minimization of the initial reaction and/or displacement peak as well as minimization of the steady-state amplitude of reaction and/or displacement. The complex stiffness approach is used to formulate the governing equations in an efficient way. Material stiffness parameters are assumed as non-linear functions of the displacement. The numerical solution is performed in the complex space. The steady-state solution in the complex space is obtained by an iterative process based on the shooting method which imposes the conditions of periodicity with respect to the known value of the period. Extension of the shooting method to the complex space is presented and verified. Non-linear behaviour of material parameters is then optimized by generic probabilistic meta-algorithm, simulated annealing. Dependence of the global optimum on several combinations of leading parameters of the simulated annealing procedure, like neighbourhood definition and annealing schedule, is also studied and analyzed. Procedure is programmed in MATLAB environment.

The materials, technique, conservation treatment and after-care of interior de um convento

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Conservação e Restauro, especialização em pintura sobre tela

Working hours and earnings: are mates’ answers coherent?

As surveys about time allocation among couples are extremely expensive, one way of reducing costs could be to query only one member of the coupler with the same set of questions about him/her and about his/her partner. In this paper we show that after carrying out a survey in this way, the responses given by one partner do not always fit the same econometric model as those obtained from the other.

Attitudes towards mentally ill in professionals working in Ndera neuropsychiatric hospital in Rwanda

ABSTRACT: This quantitative study investigated the attitudes toward the mentally ill in professionals working in Ndera neuropsychiatric hospital. The research questions explored were centered on the attitudes of directly involved and supportive professionals toward mentally ill clients and also on the difference between the attitudes of directly involved and supportive professionals toward mentally ill clients and demographic variables. The purpose of this study was to determine whether there are differences in attitude between direct care providers and supportive professionals toward the mentally ill clients. The Community Attitudes towards Mentally Ill (CAMI) scale (Dear & Taylor, 1982; Taylor, Dear & Hall, 1979; Taylor & Dear, 1981) was used. A total of 72 members of the staff, including 55 directly involved staff and 17 supportive staff members, participated in the survey. A summary interpretation of the main findings in this thesis reinforces the assumption that negative attitudes towards people with mental illness received in Ndera neuropsychiatric hospital are in existence, even though the majority have favorable attitudes towards the mentally ill. This suggests that persons with mental illness may encounter stigmatizing attitudes from mental health professionals. This study represents one of the first to explore professionals’ attitudes towards the mentally ill. It is hoped that this work will highlight the need to explore the influence of attitudes in the delivery of high quality healthcare. The provider–patient relationship is at the heart of effective treatment and the detrimental impact of prejudicial judgments on this relationship should not be ignored. This study also demonstrates that professionals with different roles report different attitudes and this suggest that they would behave differently towards patients with mental illness. The directly involved professionals have been found to have more positive attitudes than the supportive professional and this seems to show that as individuals improve their ability to interact with persons with mental illness, they become more tolerant. The present study demonstrates that the sociodemographic variables tested have no impact on the attitudes of the professionals working in Ndera neuropsychiatric hospital. The extent of mental health training (as part of general health training) and duration of experience of working in mental health settings did not influence attitudes. Finally, this study demonstrates that there is no correlation between the attitudes towards mentally ill patients and their inclusion in the process of decision-making.

Empirical models for quantification of machining damage in composite materials

Dissertação para obtenção do Grau de Doutor em Engenharia Mecânica

Le vert et le rouge: a study on the materials, techniques and meaning of the green and red colours in medieval portuguese illuminations

Dissertação para obtenção do Grau de Doutor em Conservação e Restauro

What do people do at work when they are not working?

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics