Browsing by Author "Viegas, Vítor"
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- Balanced Scorecard: A Powerful Method to Improve the Management of Educational InstitutionsPublication . Pereira, José Miguel Costa Dias; Viegas, VítorTeaching, learning and education are the main activities related with any higher education institution (HEI), be they public or private. In this context, the balanced scorecard (BSC) is a powerful method that helps the successful application of performance measurements in terms of the efficiency of the programs, processes and people of any educational institution. The key performance indicators (KPI) are crucial indicators to translate the strategy into action, improving the synergies of all the people that contribute to management success. This paper underlines the importance of the BSC model in private, governmental and non-profit organizations highlighting its implementation in a HEI. In order to clarify the main concepts of the application of the BSC method in a HEI, a hypothetical institution (IPX) is considered and a set of strategic objectives are considered in terms of financial, clients, business, learning and growth perspectives. The key parameter indicators and the action plan are defined according to the HEI vision.
- Combining Distance and Force Measurements to Monitor the Usage of Walker Assistive DevicesPublication . Pereira, José Miguel Costa Dias; Viegas, Vítor; Postolache, Octavian; Girão, Pedro SilvaThis paper presents a measurement system that can be used to monitor the usage of walker assistive devices. The forces applied on the legs of the walker device are measured using low cost force sensing resistors and a light detection and ranging device is used to evaluate several gait kinematic parameters, such as, walking speed and walking stride length. To evaluate the right usage of the walker device two walker indexes, one related with the applied forces and the other related with walker gait phases, are introduced. The measurement system includes wireless communication capabilities that enable a local and remote supervision of the measuring data.
- Combining distance and force measurements to monitor the usage of walker assistive devicesPublication . Pereira, José Miguel Costa Dias; Viegas, Vítor; Postolache, Octavian; Girão, Pedro SilvaThis paper presents a measurement system that can be used to monitor the usage of walker assistive devices. The forces applied on the legs of the walker device are measured using low cost force sensing resistors and a light detection and ranging device is used to evaluate several gait kinematic parameters, such as, walking speed and walking stride length. To evaluate the right usage of the walker device two walker indexes, one related with the applied forces and the other related with walker gait phases, are introduced. The measurement system includes wireless communication capabilities that enable a local and remote supervision of the measuring data.
- Digital to analog converter based on pulse-width addingPublication . Viegas, Vítor; Pereira, José Miguel Costa DiasThis paper presents a digital-to-analog converter (DAC) based on the pulse width created naturally by the binary counting sequence. The concept involves combining the counting impulses of the bits to form a pulse-width modulated signal, where the mean voltage is proportional to the input digital code. We propose a circuit capable of achieving this using general-purpose components. Although our design targets 8 bits, it is scalable for any number of nibbles. The paper details simulations conducted to verify the proper functioning of the circuit and to evaluate its performance. Tests were performed to determine the static characteristics of the converter, measure its differential nonlinearity (DNL), and observe its step response. In static terms, the converter exhibited negligible gain and offset errors, with a DNL below 1 LSB (least significant bit). The converter operated correctly without any missing codes. In dynamic terms, the converter demonstrated a bandwidth of 10 kHz and behaved like a second-order low-pass filter with critical damping.
- Digital to analog converter based on pulse-width addingPublication . Viegas, Vítor; Pereira, José Miguel Costa DiasThis paper presents a digital-to-analog converter (DAC) based on the pulse width created naturally by the binary counting sequence. The concept involves combining the counting impulses of the bits to form a pulsewidth modulated signal, where the mean voltage is proportional to the input digital code. We propose a circuit capable of achieving this using general-purpose components. Although our design targets 8 bits, it is scalable for any number of nibbles. The paper details simulations conducted to verify the proper functioning of the circuit and to evaluate its performance. Tests were performed to determine the static characteristics of the converter, measure its differential nonlinearity (DNL), and observe its step response. In static terms, the converter exhibited negligible gain and offset errors, with a DNL below 1 LSB (least significant bit). The converter operated correctly without any missing codes. In dynamic terms, the converter demonstrated a bandwidth of 10 kHz and behaved like a second-order lowpass filter with critical damping.
- A Dual Measurement and Stimulating System to Monitor and Promote NNSPublication . Pereira, José Miguel Costa Dias; Viegas, Vítor; Postolache, Octavian; Girão, P. S.The present paper presents a dual system that can be used to measure and to generate non-nutritive sucking (NNS) signals. The NNS measurement is based on a pressure sensor that is pneumatically connected to a silicone pacifier. By its turn, the NNS stimulator is based on a miniature pump and a miniature electro-valve that are operated by opposite phased signals to produce the pulsed pressure signal that is pneumatically applied to the silicone pacifier. The paper highlights some specific issues related with the calibration of the pneumatic signal measuring chain. Processing and wireless transmission capabilities are provided by a low-cost solution based on a microcontroller. Calibration and experimental results are also included in the paper.
- Fieldbus: Developing a Laboratory Prototype for Leaning PurposesPublication . Pereira, José Miguel Costa Dias; Viegas, Vítor; Postolache, Octavian; Girão, Pedro SilvaThis paper presents a distributed control and measurement system based on the Foundation Field Bus protocol. A system’s prototype is described together with some implementation details and experimental results. The system also includes interfaces for conventional measurement and control devices that are connected through 4-20 mA current loops. The proposed prototype seems to be a very suitable solution for teaching purposes since it is an open solution that can be used to integrate devices from different manufacturers, as long as the prototype is provided with the appropriate interface.
- Foundation fieldbus : from theory to practicePublication . Viegas, Vítor; Pereira, José Miguel Costa DiasThis paper describes the main characteristics of the Foundation Fieldbus (FF) technology considering both communication levels, namely H1 and H2, which have bit rates of 31.25 K and 100 Mbit/s, respectively. Several details about the physical layer, communication stack and user layer will be highlighted. Topics related with the configuration of instruments, as well as the design and implementation of supervision software, based on a LabVIEW interface, will be presented. A pilot plant that includes temperature, pressure, level and flow variables will be used to test and validate the capabilities of FF systems. Experimental results will be analyzed, their meaning discussed and the overall performance evaluated.
- Foundation Fieldbus: Exemplo de AplicaçãoPublication . Viegas, Vítor; Pereira, José Miguel Costa Dias
- Foundation Fieldbus: Um Resumo TécnicoPublication . Viegas, Vítor; Pereira, José Miguel Costa Dias