Distributed LQG control of a water delivery canal with feedforward from measured consumptions

This work addresses the design of distributed LQG controllers for water delivery canals that include feedforward from local farmer water consumptions. The proposed architecture consists of a network of local control agents, each connected to one of the canal pools and sharing information with their neighbors in order to act in a coordinated way. In order to improve performance, the measurement of the outflows from each pool is used as a feedforward signal. Although the feedforward action is local. It propagates due to the coordinates procedure. The paper presents the distributed LQG algorithm with feedforward and experimental results in a large scale pilot water delivery canal

Fault Tolerant Reconfigurable Control of a Water Delivery Canal - Actuators Faults

This work addresses the problem of designing fault tolerant controllers for a water delivery canal that tackle actuators faults. The type of faults considered consists of blocking of one of the gates. The detection of the fault is made by comparing the gate position command with the actual (measured) gate position. Both centralized and distributed controllers are made for local upstream water level control. Centralized controllers are multivariable LQG-LTR controllers that use a model of the system with all the available manipulated inputs (gate positions) and all the available outputs (pool levels). Initially, three gates and three pools are controlled. After the fault detection, the controller is reconfigured to use the only two still operating gates and the corresponding two pool water levels. Distributed control uses local (SISO) LQG-LTR controllers that negotiate with their neighbors in order to be coordinated. When a fault occurs, this negotiation takes place only among the controllers connected to the actuators that are not in a fault state. Experimental results obtained in a pilot canal are presented

Control of a water delivery canal with cooperative distributed MPC

This article addresses the problem of controlling pool levels in a water delivery canal using a novel cooperative distributed MPC control algorithm that incorporates stability constraints. According to a distributed control strategy, a local control agent is associated to all canal gates (actuators). In order to achieve cooperative action, each control agent computes the corresponding gate position (manipulated variable) by performing the minimization of a cost function that considers not only its local control objectives, but also the ones of their immediate neighbors. For this purpose, a MPC algorithm with stability constraints is used (SIORHC). At the beginning of each sampling interval, local control agents exchange information with their neighbors and adjust their decision in an iterative way. The resulting distributed MPC is denoted D-SIORHC and yields a stable closed-loop. Experimental results are provided to show the influence of the controller configuration parameters on the resulting performance

Predicting calcium in grape must and base wine by FT-NIR spectroscopy

Calcium content in sparkling wines may not exceed 80 mg/L due to the risk of aggregation with alginate capsules. The high calcium content usually found in wine and must emphasizes the need to develop alternative and appropriate techniques faster and cleaner than atomic absorption spectrometry (AAS). To obtain a robust model to predict calcium content, FT-NIR spectroscopy was used in 98 base white wine samples and 60 must samples from an Alentejo winery. The reference method for calcium determination was AAS technique, with a dry ashing sample procedure, as a prior treatment. Results confirmed the ability of FT-NIR as an alternative technique to AAS, to predict calcium content in grape must and base wine. Advance knowledge of the calcium content in the grape must will help avoid obtaining a mixture of musts with a high calcium content in the same container

QUALITY EVALUATION OF 'SUNBURST' CHERRIES HARVESTED AT DIFFERENT RIPENESS STAGES .

The sweet cherry ‘Sunburst’ is highly appreciated by consumers due to its organoleptic traits. Regional producers tend to harvest cherries sooner in order to increase their profits. With the aim of understanding the consequences of this we have tested the effect of different ripeness stages at the moment of harvesting on fruit quality. Quality parameters tested included external colour (L*, a*, b*), fruit texture, total soluble solids (TSS), and titratable acidity (TA). To evaluate nutritional quality total antioxidant activity was measured too. Once again, and in agreement with results obtained in previous studies, we conclude that there is no advantage in picking less ripe cherries

Time scaling internal state predictive control of a solar plant

The control of a distributed collector solar field is addressed in this work, exploiting the plant's transport characteristic. The plant is modeled by a hyperbolic type partial differential equation (PDE) where the transport speed is the manipulated flow, i.e. the controller output. The model has an external distributed source, which is the solar radiation captured along the collector, approximated to depend only of time. From the solution of the PDE, a linear discrete state space model is obtained by using time-scaling and the redefinition of the control input. This method allows overcoming the dependency of the time constants with the operating point. A model-based predictive adaptive controller is derived with the internal temperature distribution estimated with a state observer. Experimental results at the solar power plant are presented, illustrating the advantages of the approach under consideration

What makes you watch it when you can play it?: the evolution of gaming streaming and the motivational factors concerning viewership

Gaming streaming has been increasing vastly throughout this decade, having a total of 1.9 billion hours of video on TwitchTv in August alone, reflecting a 27% year- over-year growth (Gamesindustry, 2021). This dissertation’s primary objective is to quantify the motivational relevance that a Portuguese viewer has concerning gaming streaming content in the online platform denominated TwitchTv, additionally addressing the evolution of streaming and gaming. A questionnaire was created and shared on a multitude of social media platforms in order to gather data to analyze it via a dedicated software. An analysis was used in order to test the validity of the research hypothesis, being it One Sample Student’s T-Test. With this research, the purpose was to identify which of the user needs posed a positive effect regarding the usage of TwitchTv. The main conclusions were that the affective need has a positive effect in TwitchTv usage, while there’s no evidence to support other needs having a positive effect concerning TwitchTv usage. Concerning future research, this dissertation addresses the interest of expanding the scope of research to not only TwitchTv as a streaming platform but to other online networks, due to the suitable approach of User and Gratifications theory.O streaming de jogos tem tido um aumento vasto ao longo desta década, tendo totalizado 1.9 mil milhões de horas de vídeo na TwitchTv apenas em Agosto, refletindo um aumento anual de 27% (Gamesindustry, 2021). Esta dissertação tem como objetivo primário a quantificação da relevância motivacional que um espectador português tem no que diz respeito a conteúdo de streaming gaming na plataforma online denominada de TwitchTv, abordando adicionalmente a evolução de streaming e gaming. Um questionário foi criado e partilhado numa variedade de plataformas online de social media a fim de reunir dados para analisá-los via um software dedicado. Uma análise foi utilizada de modo a testar a validade das hipóteses de pesquisa, sendo esta o Teste-t para uma amostra. Com esta pesquisa, o propósito é identificar qual das necessidades do utilizador propõe um efeito positivo de acordo com o uso da TwitchTv. As conclusões principais foram as de a necessidade afetiva tem um efeito positivo no uso da TwitchTv, enquanto não existe prova para suportar as outras necessidades de terem um efeito positivo em relação ao uso da TwitchTv. No que se refere a pesquisas futuras, esta dissertação aborda o interesse de expandir o alcance da pesquisa para não apenas TwitchTv como uma plataforma de streaming, mas para outras redes online, devido à abordagem adequada da teoria do Utilizador e Gratificações

Multivariable and distributed LQG control of a water delivery canal

This work addresses the problem of the development of a distributed LQG controller for a water delivery canal. The control structure proposed relies on a set o LQG control agents interconnected through a communication network. Each of these local control agents controls a canal reach made of a pool and the corresponding downstream gate and receives information (output signal and control moves) only from the corresponding canal reach and the ones that are adjacent to it. An algorithm is proposed to achieve coordinated action of the different local control agents. This distributed control structure is compared with centralized multivariable LQG control. Several aspects with incidence on performance are addressed, including the modification of the quadratic cost to ensure a constraint on closed-loop poles, the use of a nonlinear filter to limit noise effects and the impact of a quantization commonly forced in gate position. Experimental results obtained in a pilot canal are presented

Actuator Fault Tolerant LQG Control of a Water Delivery Canal

The problem of reconfiguration of the control system to mitigate the effects of actuator faults in a water delivery canal is addressed in this paper. When a fault in an actuator is detected and isolated, the controller is reconfigured by changing the set of manipulated and process variables and using a different controller, associated to a different plant model, in a hybrid systems framework. In order to prevent instability that may be associated with switching among controllers, a dwell time condition is used. Both centralized and distributed control, a game approach is followed to coordinate the different local controllers. Experimental results are presented

EFFECT OF DIFFERENT STORAGE CONDITIONS ON NUTRITIONAL AND QUALITY PARAMETERS OF 'SWEETHEART' CHERRY.

Abstract The sweet cherry ‘Sweetheart’, although having a short shelf life, is highly appreciated by consumers due to its organoleptic characteristics. Different storage methods were tested to study the maintenance of quality during a period of 27 days: 1) cold (air at 1°C and 95% relative humidity) (CC), 2) cold and polypropylene film bags (1°C and 95% relative humidity) (MA) and 3) cold and controlled atmosphere (1°C, 95% RH, 10% CO2 and 8% O2) (CA). Quality parameters tested included external colour (L*, a*, b*), total soluble solids (TSS), and titratable acidity (TA). To evaluate nutritional quality anthocyanins, total antioxidant activity, and total phenolics were measured. Results allow us to say that phenolic compounds were relatively stable and similar during storage in CC and MA. Cherries stored under CA conditions presented lowest concentrations of phenolic compounds. Phenolic compounds, total anthocyanins and antioxidant activity were inversely correlated with values of colour coordinates. Considering all the evaluations done during this work it is unquestionable that fruits stored in controlled atmosphere conditions had significantly different quality