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In this paper a new simulation environment for a virtual laboratory to educational proposes is presented. The Logisim platform was adopted as the base digital simulation tool, since it has a modular implementation in Java. All the hardware devices used in the laboratory course was designed as components accessible by the simulation tool, and integrated as a library. Moreover, this new library allows the user to access an external interface. This work was motivated by the needed to achieve better learning times on co-design projects, based on hardware and software implementations, and to reduce the laboratory time, decreasing the operational costs of engineer teaching. Furthermore, the use of virtual laboratories in educational environments allows the students to perform functional tests, before they went to a real laboratory. Moreover, these functional tests allow to speed-up the learning when a problem based approach methodology is considered.

Industry is a fundamental sector that allows mass production to support a large population. As population grows, many industries produce large amounts of industrial effluents with different pollutants, that must be removed at the industrial wastewater treatment plants, with the consequent production of large amounts of sludge. The present study was conducted to identify and evaluate different sludge treatment/valorisation methodologies, being given priority to the valorisation in detriment of the elimination operations, like incineration or landfill. Therefore, sludges from the wastewater treatment plant of a resin industry, after dehydration operation by a press, were submitted to several valorisation methodologies, such as: application in anaerobic digestion aiming the production of biogas and allowing energy recovery, use in the preparation of adsorbents for the treatment of industrial wastewater, use as cement replacement in mortar production, and application of heterogeneous catalysts to produce biodiesel. The results revealed that all methodologies can be applied as sludge recovery. However, it is possible to conclude that the most promising industrial sludge treatment/recovery hypothesis is anaerobic co-digestion followed by the production of heterogeneous catalysts for biodiesel production.

A Life Cycle Assessment (LCA) with focus on carbon footprint, followed by Life Cycle Costing (LCC) of municipal solid waste (MSW) management were conducted in a residential area of a medium-sized European city of 80,000 inhabitants. The initial results showed high environmental impacts and lack of economic sustainability, due to the high amounts of waste landfilled, the low extent of separate collection, low performance of mechanical-biological treatment as well as absence from alternatives to landfilling of non-recyclable materials. Taking this result as a baseline scenario, three improvement.s were tested with the aim of turning the carbon footprint of the local MSW management system into a neutral value: (i) increased separate collection of recyclables, (ii) enhanced biogas production and (iii) refuse-derived fuel (RDF) production. Successively adding the improvements, three alternative improved scenarios were defined, until reaching a negative carbon footprint, meaning that an optimised system would avoid GHG emissions. The proposed changes were sufficient to achieve carbon neutrality, as well as reduce overall environmental impacts, but were not enough for achieving economic sustainability due to the great influence of collection costs, especially for separate collection. It was concluded that by using an adequate combination of several treatment options and increasing the separate collection of recyclable materials it is possible to turn MSW management into a carbon neutral activity as well as improve its economic balance.

Abstract One of the critical areas in the outer shell of household refrigerators is the compressor compartment, which has relatively high temperatures, due to the heat generated while the compressor is running. This implies a larger heat transfer to the interior air volume and, consequently, more energy consumption. One way to decrease this temperature is to ventilate the base of the refrigerator with a small fan. In the research carried out, a decrease of 11 °C in the temperature of the surfaces close to the compressor was recorded, when the fan was running. The implications of this effect can be seen at two levels: changes in the temperature distribution at the bottom of the refrigerator envelope and the resulting dynamic effects, and a decrease in energy consumption of the entire system. Consequently, there are lower CO 2 emissions to the environment, making household refrigerators more efficient and sustainable.

This paper deals with the medium between two reconfigurable sensor nodes characterized by radio interfaces that support multiple channels for exchanging real-time messages under energy constraints. These constraints are violated if the consumed energy in transmission is higher than the remaining quantity of energy. A reconfiguration, i.e., any addition or removal of tasks in devices and consequently of messages on the medium, can cause the violation of real-time or energy constraints at run time. To achieve a feasible scheduling in time (i.e., message deadlines will be respected) and energy (i.e., there is available energy) on the medium, we propose new dynamic solutions: Balance, Dilute, and a Combination of them to manage any addition or removal of messages. The proposed approach utilizes the energy harvesting techniques and the PowerControl algorithm to reduce the nonharvested consumed energy. The proposed strategies achieve significant improvement over existing methods and provide the highest percentage of adding messages, with a lower average in response time and energy consumption. They reach a percentage of success in adding the highest priority messages while meeting deadlines up to 85%.

This work proposes a methodology for predicting the typical daily load profile of electricity usage based on static data obtained from surveys. The methodology intends to: (1) determine consumer segments based on the metering data using the k-means clustering algorithm, (2) correlate survey data to the segments, and (3) develop statistical and machine learning classification models to predict the demand profile of the consumers. The developed classification models contribute to make the study and planning of demand side management programs easier, provide means for studying the impact of alternative tariff setting methods and generate useful knowledge for policy makers.

Recognizing the benefit that one can get by exploiting the Micro-Grid (MG) concept, as an active part of the Low Voltage (LV) network comprising several micro-generation (µG) sources, controllable loads and storage devices, is a key issue towards the MG concept deployment. Furthermore, the MG concept is extended into Multi-Micro Grid (MMG) concept, identifying the benefits that can be obtained at Medium Voltage (MV) level. The main idea behind this research is to show what one gains and what one looses by setting up the MG concept. Therefore, the benefits reported, are evaluated through a cost-benefit approach by modeling the problem as a multi-attribute problem using several Decision-Aid (DA) techniques to capture different Decision Maker (DM) preference structures.

A control technique of multilevel converter topologies based on Direct Lyapunov Control method is presented in this paper for integration of Distributed Generation (DG) resources into the power grid. The compensation of instantaneous variations in the reference current components in ac-side and dc-voltage variations of cascaded capacitors in dc-side of the interfacing system are considered properly, which is the main contribution and novelty of this work in comparison with other control strategies. The proposed control technique provides the continuous injection of active power in fundamental frequency from DG sources to the grid. In addition, reactive power and harmonic current components of loads are provided with a fast dynamic response; thereby, achieving sinusoidal grid currents in phase with load voltages, while the required power from load side is more than the maximum capacity of interfaced converter, is possible. Simulation results confirm the effectiveness of the proposed control strategy in DG technology during dynamic and steady-state operating conditions.

This work addresses the problem of transmission expansion-planning in the context of the reregulation and liberalization of power systems. The transmission expansion-planning problem is formulated as an integer problem and it is solved keeping that characteristic using simulated annealing. In the scope of the access to the transmission networks and the corresponding payments for use of networks, the paper discusses the advantages and drawbacks from adopting several cost methods and, more specifically, short-term and long-term nodal marginal prices. Long-term marginal prices are computed in the framework of the simulated annealing algorithm and led to the calculation of the marginal based remuneration to the transmission company. The paper includes case studies based on the Portuguese 400/220/150 kV network and on a didactic 6-bus system.