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Publicações

2021

Hybrid dynamic logic institutions for event/data-based systems

Autores
Hennicker, R; Knapp, A; Madeira, A;

Publicação
FORMAL ASPECTS OF COMPUTING

Abstract
We propose E-down arrow((D) over right arrow)-logic as a formal foundation for the specification and development of event-based systems with data states. The framework is presented as an institution in the sense of Goguen and Burstall and the logic itself is parametrised by an underlying institution (D) over right arrow whose structures are used to model data states. E-down arrow((D) over right arrow)-logic is intended to cover a broad range of abstraction levels from abstract requirements specifications up to constructive specifications. It uses modal diamond and box operators over complex actions adopted from dynamic logic. Atomic actions are pairs e/psi where e is an event and psi a state transition predicate capturing the allowed reactions to the event. Towrite concrete specifications of recursive process structureswe integrate (control) state variables and binders of hybrid logic. The semantic interpretation relies on event/data transition systems. For the presentation of constructive specifications we propose operational event/data specifications allowing for familiar, diagrammatic representations by state transition graphs. We show that E-down arrow((D) over right arrow)-logic is powerful enough to characterise the semantics of an operational specification by a single E-down arrow((D) over right arrow)-sentence. Thus the whole (formal) development process for event/data-based systems relies on E-down arrow((D) over right arrow)-logic and its semantics as a common basis. It is supported by a variety of implementation constructors which can express, among others, event refinement and parallel composition. Due to the genericity of the approach, it is also possible to change a data state institution during system development when needed. All steps of our formal treatment are illustrated by a running example.

2021

Boosters of satisfaction, performance and employee loyalty: application to a recruitment and outsourcing information technology organization

Autores
Veloso, CM; Sousa, B; Au Yong Oliveira, M; Walter, CE;

Publicação
JOURNAL OF ORGANIZATIONAL CHANGE MANAGEMENT

Abstract
Purpose This study applies an Employee Satisfaction Index (ESI) model to quantify the level of job satisfaction and explores the factors that influence employee satisfaction, performance and loyalty to an information technology recruitment and outsourcing organization in Portugal. Design/methodology/approach As an instrument of data collection, questionnaire was applied to the company's employees, which was divided into two parts: the first part consisted of a previous questionnaire, with questions related to sociodemographic characterization; the second part consisted of the ESI. The company operates only in the information technology (IT) market, and there are currently 300 consultants with different skills. Findings The results confirm that the company's employees are globally satisfied, and this satisfaction contributes positively and significantly to the reinforcement of contextual performance and to their loyalty to this organization. Originality/value Job satisfaction takes on a growing interest in understanding quality of life, strategic management and organizational performance. Job satisfaction contributes to the professional finding, that is, in employees' activity and in adopting positive attitudes toward customer satisfaction, thus promoting organizational performance.

2021

Simultaneous Calibration of Grapevine Phenology and Yield with a Soil-Plant-Atmosphere System Model Using the Frequentist Method

Autores
Yang, CY; Menz, C; Fraga, H; Reis, S; Machado, N; Malheiro, AC; Santos, JA;

Publicação
AGRONOMY-BASEL

Abstract
Reliable estimations of parameter values and associated uncertainties are crucial for crop model applications in agro-environmental research. However, estimating many parameters simultaneously for different types of response variables is difficult. This becomes more complicated for grapevines with different phenotypes between varieties and training systems. Our study aims to evaluate how a standard least square approach can be used to calibrate a complex grapevine model for simulating both the phenology (flowering and harvest date) and yield of four different variety-training systems in the Douro Demarcated Region, northern Portugal. An objective function is defined to search for the best-fit parameters that result in the minimum value of the unweighted sum of the normalized Root Mean Squared Error (nRMSE) of the studied variables. Parameter uncertainties are estimated as how a given parameter value can determine the total prediction variability caused by variations in the other parameter combinations. The results indicate that the best-estimated parameters show a satisfactory predictive performance, with a mean bias of -2 to 4 days for phenology and -232 to 159 kg/ha for yield. The corresponding variance in the observed data was generally well reproduced, except for one occasion. These parameters are a good trade-off to achieve results close to the best possible fit of each response variable. No parameter combinations can achieve minimum errors simultaneously for phenology and yield, where the best fit to one variable can lead to a poor fit to another. The proposed parameter uncertainty analysis is particularly useful to select the best-fit parameter values when several choices with equal performance occur. A global sensitivity analysis is applied where the fruit-setting parameters are identified as key determinants for yield simulations. Overall, the approach (including uncertainty analysis) is relatively simple and straightforward without specific pre-conditions (e.g., model continuity), which can be easily applied for other models and crops. However, a challenge has been identified, which is associated with the appropriate assumption of the model errors, where a combination of various calibration approaches might be essential to have a more robust parameter estimation.

2021

Enhanced Ultraviolet Spectroscopy by Optical Clearing for Biomedical Applications

Autores
Carneiro, I; Carvalho, S; Henrique, R; Selifonov, A; Oliveira, L; Tuchin, VV;

Publicação
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS

Abstract
In this paper, we describe the combination of ultraviolet (UV) spectroscopy with the optical clearing technique to induce new tissue windows, evaluate their efficiency, study the diffusion properties of agents and discriminate cancer. The use of highly concentrated glycerol solutions has induced high efficiency clearing effects in the UV, both in human colorectal and gingival tissues. The protein dissociation rate obtained for colorectal tissues was approximately 3 times higher in pathological than in normal mucosa and the kinetics of diffuse reflectance in the UV allowed to estimate the diffusion coefficient for water in gingival mucosa at glycerol action as (1.78 +/- 0.26) x 10(-6) cm(2)/s.

2021

Housing situation of students during the COVID-19 pandemic – a case study from Poland and Portugal

Autores
Grzywinska-Rapca, M; Duarte, N; Janusz, M;

Publicação
Olsztyn Economic Journal

Abstract
The occurrence of the first illnesses of the inhabitants of Poland and Portugal caused decision-makers to introduce many changes in the functioning of economic units in various areas. This document aims to answer the questions of whether the changes related to the occurrence of COVID-19 had a significant impact on the housing situation of students by answering two questions: (1) How has the pandemic affected the change in the form of residence? (2) What changes in the provisions of the contract do students expect after returning to the full-time form? The empirical study was conducted based on data obtained from a survey. The research was conducted in May and June 2021 on a sample of 599 students at the University of Warmia and Mazury in Olsztyn and the School of Technology and Management of Porto Polytechnic in Portugal. The analysis related to the determination of statistically significant interdependencies of socio-demographic characteristics of respondents with their attitudes, and a multidimensional method of comparative analysis was used, known as correspondence analysis. As a method of recording data in the analysis of correspondence, the Burt matrix was used. The result of the statistical analysis was the identification of structural relationships between variables and objects (respondents). The results showed different behaviours related to housing conditions in Poland and Portugal. Polish students, due to the epidemiological situation, were mostly forced to change their place of residence, which was usually associated with returning to their family home. This trend was not observed for students in Portugal (median response: Housing had not been affected in any way by the pandemic).

2021

Delivering Critical Stimuli for Decision Making in VR Training: Evaluation Study of a Firefighter Training Scenario

Autores
Monteiro, P; Melo, M; Valente, A; Vasconcelos Raposo, J; Bessa, M;

Publicação
IEEE TRANSACTIONS ON HUMAN-MACHINE SYSTEMS

Abstract
The goal for a virtual reality (VR) training system is to enable trainees to acquire all the knowledge they need to perform effectively in a real environment. Such a system should provide an experience so authentic that no further real-world training is necessary, meaning that it is sufficient to train in VR. We evaluate the impact of a haptic thermal stimulus, which is of paramount importance to decision making, on trainees performance and knowledge acquisition. A thermal device was created to deliver the stimulus. As a proof of concept, a procedure from firefighter training is selected, in which sensing the temperature of a door with one's hand is essential. The sample consisted of 48 subjects divided among three experimental scenarios: one in which a virtual thermometer is used (visual stimulus), another in which the temperature is felt with the hand (thermal stimulus) and a third in which both methods are used (visual + thermal stimuli). For the performance evaluation, we measured the total time taken, the numbers of correctly executed procedures and identified neutral planes, the deviation from the target height, and the responses to a knowledge transfer questionnaire. Presence, cybersickness, and usability are measured to evaluate the impact of the haptic thermal stimulus. Considering the thermal stimulus condition as the baseline, we conclude that the significantly different results in the performance among the conditions indicate that the better performance in the visual-only condition is not representative of the real-life performance. Consequently, VR training applications need to deliver the correct stimuli for decision making.

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