Sustainable Built Environments Senior Capstone Project / Across the world, populations continue to grow while water supplies stay fixed. In the American Southwest, water supplies are at an all time low, yet warm, favorable conditions continue to lure residents to the area. With some of the country’s lowest fresh water reserves, it is imperative that changes are made to water usage trends and associated energy inefficiencies. An analysis of water usage in Tucson was conducted to evaluate potential solutions for reducing consumption and to correspondingly shrink energy usage. Case studies were investigated, census numbers were used to roughly calculate statistics, existing knowledge on water conservation techniques were researched, and alternative water filtration as well as distribution systems were scrutinized for their viability amongst current infrastructure. The potential to reduce water usage is greatest with the largest user of water in Tucson, the single-family residence. On average the single-family residence is capable of effectively saving nearly 25,000 gallons of water per year with efficient fixtures, another 25,000 gallons per year by reducing outdoor water use by half, and another 10,625 gallons by utilizing rainwater harvesting. Combine those savings and multiply them by the 225,000-240,000 single-family residents estimated to be in Tucson and the savings reach more than five billion gallons a year, effectively almost cutting water consumption in Tucson by a fifth. Further, to keep remaining usage impacts negligible, implementation of an indirect or direct potable water reuse system could satisfy populations for decades by reusing water that would normally be discarded as effluent. Water consumption must be curved so that it can satisfy a growing population’s needs. Amongst residents of Tucson, single-family residences have the greatest potential to reduce water and associated energy needs. Through conservation techniques, water harvesting, reducing outdoor water usage, and potable reuse, limited water supplies can satisfy future generations to come.

No description available.

Decision-making is an important operation for any autonomous system. Robots in particular must observe their environment and compute appropriate responses. For solitary robots and centralized multiple-robot systems, decision-making is a relatively straightforward operation, since only a single agent (either the solitary robot or the single central controller) is solely responsible for the operation. The problem is much more complex in a decentralized system, to the point where optimal decision-making is intractable in the general case. Decentralized multiple-robot systems (dec-MRS) are robotic teams in which no robot is in authority over any others. The globally observed behaviour of dec-MRS emerges out of the individual robots’ local interactions with each other. This makes system-level decision-making, an operation in which an entire dec-MRS cooperatively makes a decision, a difficult problem. Social insects have long been a source of inspiration for dec-MRS research, and their example is followed in this work. Honeybees and Temnothorax ants must make group decisions in order to choose a new nest site whenever they relocate their colonies. Like the simple robots that compose typical dec-MRS, the insects utilize local, peer-to-peer behaviours to make good, cooperative decisions. This thesis examines their decision-making strategies in detail and proposes a three-phase framework for system-level decision-making by dec-MRS. Two different styles of decision are described, and experiments in both simulation and with real robots were carried out and presented here to demonstrate the framework’s decision-making ability. Using only local, anonymous communication and emergent behaviour, the proposed collective decision-making framework is able to make good decisions reliably, even in the presence of noisy individual sensing. Social cues such as consensus and quorum testing enables the robots to predicate their behaviour during the decision-making process on the global state of their system. Furthermore, because the operations carried out by the individual robots are so simple, and because their complexity to the individual robots is independent of the population size of a dec-MRS, the proposed decision-making framework will scale well to very large population sizes.

A precariedade do tratamento dos esgotos sanitários no país, principalmente em pequenos municípios, aliado à falta de recursos financeiros, necessitam apoio tecnológico e científico, sendo motivo de preocupação e atenção. O objetivo geral deste trabalho é propor alternativas de sistemas de tratamento de esgotos sanitários urbanos para a cidade de Feliz/RS, município brasileiro de pequeno porte, visando à melhoria da qualidade dos seus recursos hídricos. Para a realização deste trabalho foi necessário realizar o diagnóstico do sistema de tratamento de esgotos sanitários na área urbana do município; avaliar o impacto gerado pelos esgotos sanitários urbanos no manancial hídrico do município e propor sistemas de tratamento de esgotos sanitários mais sustentáveis e que atendam os padrões de emissões de efluentes líquidos, permitidos pela legislação, em águas superficiais. A estratégia de pesquisa adotada neste trabalho foi a pesquisa construtiva, cuja metodologia foi dividida em três etapas: I) delimitação da área geográfica e análise documental; II) levantamento quantitativo de domicílios, por bairro, e coleta de amostras de água, em três pontos do manancial que banha o município de Feliz; III) apresentação de propostas de sistemas de tratamento de esgotos sanitários. Nas etapas II e III houve a aplicação do modelo matemático, QUAL2K, no trecho do rio estudado, no município de Feliz, simulando as diversas condições da qualidade da água e comparando-as com os padrões de emissões de efluentes permitidos pela legislação, em águas superficiais. Os resultados mostraram que a região urbana do município de Feliz apresenta inexpressivos índices de tratamento de esgotos domésticos. Os esgotos lançados sem tratamento, provenientes das redes pluviais, são os principais poluentes do rio, na área urbana. Foram pesquisados sistemas descentralizados de tratamento de esgotos propostos, entre os quais: wetlands, UASB e filtro anaeróbio, e tanque séptico e infiltração. A simulação mostra que estes sistemas propostos poderão se tornar efetivos, no sentido de tratar os esgotos domésticos urbanos de forma mais sustentável e na redução dos níveis dos parâmetros analisados, embora não atinjam os limites estabelecidos pela legislação, para que o trecho estudado possa ser enquadrado como atendendo à legislação e aos anseios da população local. / The lack of adequate sewage treatment in the country, especially in small municipalities, together with the scarceness of financial resources, requires technological and scientific support, being a major concern and asks for the due attention. The general objective of this work is to propose alternative systems of urban sewage treatment for the municipality of Feliz, a small Brazilian municipality in the State of Rio Grande do Sul, , , aiming at improving the quality of its water resources. The elaboration of this work included a system diagnosis of sewage treatment in the urban area, the assessment of the impact of sewage generated by urban water sources and a proposal for the treatment of sewage systems in a more sustainable way, that meets the emissions standards for effluents , as allowed by legislation, in surface waters. The research strategy adopted in this work was the constructive research, whose methodology was applied in three steps: I) a geographical area delimitation and documental analysis II) a quantitative survey of households, by area, and collection of water samples at three points in the river that crosses the town of Feliz, III) a presentation of proposals for more sustainable sewage systems treatment. In stages II and III a mathematical model, QUAL2K, was applied in the studied stretch of the river, simulating the various conditions of water quality and comparing them with the effluent emissions standards allowed by law, in surface waters. The results showed that the urban area of Feliz presents a very low rate of domestic sewage treatment. The untreated sewage released into the local system of stormwater is the main pollutant of the river in the urban area. The following decentralized systems of sewage treatment were studied: wetlands, anaerobic filter and UASB and septic tank and seepage. The simulation showed that these proposed systems can be effective in order to treat more sustainably the domestic sewage and to reduce the levels of the analyzed parameters, although not reaching the limits established by the legislation for the studied stretch so to enabled it to be framed as being in compliance with the Brazilian legislation and with the wishes of the local community.

A precariedade do tratamento dos esgotos sanitários no país, principalmente em pequenos municípios, aliado à falta de recursos financeiros, necessitam apoio tecnológico e científico, sendo motivo de preocupação e atenção. O objetivo geral deste trabalho é propor alternativas de sistemas de tratamento de esgotos sanitários urbanos para a cidade de Feliz/RS, município brasileiro de pequeno porte, visando à melhoria da qualidade dos seus recursos hídricos. Para a realização deste trabalho foi necessário realizar o diagnóstico do sistema de tratamento de esgotos sanitários na área urbana do município; avaliar o impacto gerado pelos esgotos sanitários urbanos no manancial hídrico do município e propor sistemas de tratamento de esgotos sanitários mais sustentáveis e que atendam os padrões de emissões de efluentes líquidos, permitidos pela legislação, em águas superficiais. A estratégia de pesquisa adotada neste trabalho foi a pesquisa construtiva, cuja metodologia foi dividida em três etapas: I) delimitação da área geográfica e análise documental; II) levantamento quantitativo de domicílios, por bairro, e coleta de amostras de água, em três pontos do manancial que banha o município de Feliz; III) apresentação de propostas de sistemas de tratamento de esgotos sanitários. Nas etapas II e III houve a aplicação do modelo matemático, QUAL2K, no trecho do rio estudado, no município de Feliz, simulando as diversas condições da qualidade da água e comparando-as com os padrões de emissões de efluentes permitidos pela legislação, em águas superficiais. Os resultados mostraram que a região urbana do município de Feliz apresenta inexpressivos índices de tratamento de esgotos domésticos. Os esgotos lançados sem tratamento, provenientes das redes pluviais, são os principais poluentes do rio, na área urbana. Foram pesquisados sistemas descentralizados de tratamento de esgotos propostos, entre os quais: wetlands, UASB e filtro anaeróbio, e tanque séptico e infiltração. A simulação mostra que estes sistemas propostos poderão se tornar efetivos, no sentido de tratar os esgotos domésticos urbanos de forma mais sustentável e na redução dos níveis dos parâmetros analisados, embora não atinjam os limites estabelecidos pela legislação, para que o trecho estudado possa ser enquadrado como atendendo à legislação e aos anseios da população local. / The lack of adequate sewage treatment in the country, especially in small municipalities, together with the scarceness of financial resources, requires technological and scientific support, being a major concern and asks for the due attention. The general objective of this work is to propose alternative systems of urban sewage treatment for the municipality of Feliz, a small Brazilian municipality in the State of Rio Grande do Sul, , , aiming at improving the quality of its water resources. The elaboration of this work included a system diagnosis of sewage treatment in the urban area, the assessment of the impact of sewage generated by urban water sources and a proposal for the treatment of sewage systems in a more sustainable way, that meets the emissions standards for effluents , as allowed by legislation, in surface waters. The research strategy adopted in this work was the constructive research, whose methodology was applied in three steps: I) a geographical area delimitation and documental analysis II) a quantitative survey of households, by area, and collection of water samples at three points in the river that crosses the town of Feliz, III) a presentation of proposals for more sustainable sewage systems treatment. In stages II and III a mathematical model, QUAL2K, was applied in the studied stretch of the river, simulating the various conditions of water quality and comparing them with the effluent emissions standards allowed by law, in surface waters. The results showed that the urban area of Feliz presents a very low rate of domestic sewage treatment. The untreated sewage released into the local system of stormwater is the main pollutant of the river in the urban area. The following decentralized systems of sewage treatment were studied: wetlands, anaerobic filter and UASB and septic tank and seepage. The simulation showed that these proposed systems can be effective in order to treat more sustainably the domestic sewage and to reduce the levels of the analyzed parameters, although not reaching the limits established by the legislation for the studied stretch so to enabled it to be framed as being in compliance with the Brazilian legislation and with the wishes of the local community.

A precariedade do tratamento dos esgotos sanitários no país, principalmente em pequenos municípios, aliado à falta de recursos financeiros, necessitam apoio tecnológico e científico, sendo motivo de preocupação e atenção. O objetivo geral deste trabalho é propor alternativas de sistemas de tratamento de esgotos sanitários urbanos para a cidade de Feliz/RS, município brasileiro de pequeno porte, visando à melhoria da qualidade dos seus recursos hídricos. Para a realização deste trabalho foi necessário realizar o diagnóstico do sistema de tratamento de esgotos sanitários na área urbana do município; avaliar o impacto gerado pelos esgotos sanitários urbanos no manancial hídrico do município e propor sistemas de tratamento de esgotos sanitários mais sustentáveis e que atendam os padrões de emissões de efluentes líquidos, permitidos pela legislação, em águas superficiais. A estratégia de pesquisa adotada neste trabalho foi a pesquisa construtiva, cuja metodologia foi dividida em três etapas: I) delimitação da área geográfica e análise documental; II) levantamento quantitativo de domicílios, por bairro, e coleta de amostras de água, em três pontos do manancial que banha o município de Feliz; III) apresentação de propostas de sistemas de tratamento de esgotos sanitários. Nas etapas II e III houve a aplicação do modelo matemático, QUAL2K, no trecho do rio estudado, no município de Feliz, simulando as diversas condições da qualidade da água e comparando-as com os padrões de emissões de efluentes permitidos pela legislação, em águas superficiais. Os resultados mostraram que a região urbana do município de Feliz apresenta inexpressivos índices de tratamento de esgotos domésticos. Os esgotos lançados sem tratamento, provenientes das redes pluviais, são os principais poluentes do rio, na área urbana. Foram pesquisados sistemas descentralizados de tratamento de esgotos propostos, entre os quais: wetlands, UASB e filtro anaeróbio, e tanque séptico e infiltração. A simulação mostra que estes sistemas propostos poderão se tornar efetivos, no sentido de tratar os esgotos domésticos urbanos de forma mais sustentável e na redução dos níveis dos parâmetros analisados, embora não atinjam os limites estabelecidos pela legislação, para que o trecho estudado possa ser enquadrado como atendendo à legislação e aos anseios da população local. / The lack of adequate sewage treatment in the country, especially in small municipalities, together with the scarceness of financial resources, requires technological and scientific support, being a major concern and asks for the due attention. The general objective of this work is to propose alternative systems of urban sewage treatment for the municipality of Feliz, a small Brazilian municipality in the State of Rio Grande do Sul, , , aiming at improving the quality of its water resources. The elaboration of this work included a system diagnosis of sewage treatment in the urban area, the assessment of the impact of sewage generated by urban water sources and a proposal for the treatment of sewage systems in a more sustainable way, that meets the emissions standards for effluents , as allowed by legislation, in surface waters. The research strategy adopted in this work was the constructive research, whose methodology was applied in three steps: I) a geographical area delimitation and documental analysis II) a quantitative survey of households, by area, and collection of water samples at three points in the river that crosses the town of Feliz, III) a presentation of proposals for more sustainable sewage systems treatment. In stages II and III a mathematical model, QUAL2K, was applied in the studied stretch of the river, simulating the various conditions of water quality and comparing them with the effluent emissions standards allowed by law, in surface waters. The results showed that the urban area of Feliz presents a very low rate of domestic sewage treatment. The untreated sewage released into the local system of stormwater is the main pollutant of the river in the urban area. The following decentralized systems of sewage treatment were studied: wetlands, anaerobic filter and UASB and septic tank and seepage. The simulation showed that these proposed systems can be effective in order to treat more sustainably the domestic sewage and to reduce the levels of the analyzed parameters, although not reaching the limits established by the legislation for the studied stretch so to enabled it to be framed as being in compliance with the Brazilian legislation and with the wishes of the local community.

Climate change and increased pressure on water resources through urban and peri-urban population growth present some major uncertainties to the sustainable provision of good quality water, sanitation and hygiene (WASH) services, particularly to small-scale decentralized systems which are considered more vulnerable compared to centralized systems. The concept of “resilience” could be useful when dealing with such uncertainties. It deals with planning for shocks and stressors which could help address long-term water security and sanitation challenges. The aim of this research is to explore the relevance of the concept of resilience in dealing with uncertainties for decentralized WASH systems. Through literature review, interviews (n=22) and group discussions (n=18), the relevance of the 7 resilience principles, developed by SRC, to WASH planning for decentralized systems was explored. WHO community water and sanitation planning guidelines were reviewed to determine how resilience could add useful aspects to management of decentralised WASH systems.  Results showed that the resilience concept is important in planning and management of decentralized WASH systems, since, with the resilience principles as a basis, there is potential to involve different stakeholders to share knowledge, skills and resources across multiple scales. The three resilience principles considered most important from the 7 SRC resilience principles for decentralized WASH were identified as: 1) Broadening participation, 2) Maintenance of diversity and redundancy, and 3) Management of slow changing variables and feedbacks. Other important WASH aspects missing from the resilience principles were: 1) Contextuality, 2) Accountability, 3) Equity and human rights, 4) Monitoring and maintenance, 5) Resource capacity. Two case studies served as examples of how decentralized WASH systems are managed in a high-income country (Värmdö, Sweden) and  a low/middle income country (MSETO, Kenya). In both cases, applied resilience principles were identified together with areas of improvement. With reference to resilience, Värmdö municipality showed strength in the flow of information (connectivity) between actors but lacked integrated WASH planning guidelines and diversity of water supplies. The MSETO project exhibited strength in overlapping responsibilities (polycentric governance) but lacked management of slow changing variables and feedbacks, linked to the lack of adequate re-sources. The analysis of WHO Water Safety Plans and sanitation safety planning guidelines through the resilience framework revealed that the WHO guidelines have a heavy focus on technical aspects and lack an integrated approach involving polycentric governance and complex adaptive system thinking. There is need for the revision of the guide-lines to incorporate community social aspects, strategies of improving water availability and consideration of complex adaptive systems thinking. Municipalities and practitioners are recommended to consider resilience principles as well as the identified missing aspects in WASH planning and interventions. Further research is needed investigating necessary conditions for the application of resilience principles and important trade-offs.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This master thesis analyses and implements a stand-alone photovoltaic system based on decentralized Multi String topology. The proposed system is composed of a set of DCDC converters linked to the PV arrays of panels, a bidirectional converter to perform the control of the charge/discharge process of the battery bank and ensure the specifications of DC link and a full-bridge inverter that feed the AC loads. Therefore, all operation modes that the stand-alone PV system can work are presented and analyzed. As the chief aim is to ensure the energy balance of the stand-alone PV system, are presented independents control loops for each converter of the PV system and a propose of a supervisory control that, based on information about the conditions of the DC link and the bank of batteries, defines each operation mode should be active, in order to maximize the power extracted from the PV arrays, the life cycle of the battery bank and ensuring the uninterrupted feeding of energy to the loads. Finally, simulation and experimental results validate the operation of the proposed system under different load and solar radiation conditions. / Este trabalho analisa e implementa um sistema fotovoltaico autônomo baseado no conceito de topologia descentralizada do tipo Multi String . O sistema proposto é constituído de um conjunto de conversores CC-CC vinculados aos arranjos de painéis, um conversor bidirecional para controle da carga e descarga do banco de baterias e um inversor de saída que fornece a alimentação CA as cargas. Todos os modos de operação em que o sistema PV autônomo proposto pode funcionar são apresentados e analisados. Com o objetivo principal de assegurar o balanço de energia do sistema PV autônomo, são apresentadas malhas de controle independentes para cada conversor do sistema PV e a proposta de um sistema supervisório o qual, de posse de informações sobre o estado do barramento CC e banco de baterias, define qual modo de operação deve estar ativo, maximizando a potência extraída dos arranjos PV, a vida útil do banco de baterias e garantindo um fornecimento contínuo de energia às cargas. Por fim, resultados de simulação e experimentais validam o funcionamento do sistema proposto em diferentes condições de carga e radiação solar.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / A geraÃÃo de energia elÃtrica que combina o desenvolvimento humano com menos impactos ambientais e menos poluiÃÃo à um item fundamental no inÃcio deste sÃculo. Assim, a principal motivaÃÃo da caminhada atual à o desenvolvimento de novas topologias de sistemas descentralizados de fornecimento de energia. O objetivo à desenvolver um conversor bidirecional com alto ganho tensÃo, que à projetado para operar em dois modos: boost e buck. A topologia apresentada permite a transferÃncia bidirecional de energia, o que em algumas situaÃÃes, à transferida para o barramento CC, ou para um banco de baterias. O conversor à projetado para um potÃncia de 2 kW. à apresentado o desenvolvimento teÃrico e experimental do projeto para os dois modos de operaÃÃo. A fim de validar a proposta, sÃo apresentados resultados experimentais, para uma potÃncia de 1 kW. Os resultados foram satisfatÃrios e seu rendimento global de 93%. O protÃtipo foi testado em condiÃÃes diferentes que podem ser encontradas no dia-a-dia. / The achievement of energy generation which combines human development with less environment pollution impact is a key item in the premises of this century. Thus the main motivation of the present walk is the development of new topologies for decentralized supply systems. The objective is to develop a bidirectional converter with high voltage gain, which is designed to operate in two modes: step-up (boost) and step down (buck). The presented topology enables to bidirectional energy transfer, which in some situations it is returned to the load DC bus, formed by a back of batteries. The converter is designed for 2 kW linear load power. If is presented theoretical development and experimental designs for the two operation modes. In order to validate the proposal, it is presented experimental results, from 1 kW laboratory prototype are presented as well and 93% overall efficiency. The prototype was tested in different conditions that may be found daily.

BFT consensus algorithms can ensure the consistency of distributed systems where nodes may behave arbitrarily due to faults or intentional malicious actions. However, most of the practical BFT consensus algorithms are leader-based. In an adversarial network, leader-based BFT consensus algorithms exhibit vulnerabilities and lack resilience. Byzantine leaders can pose a potential threat to the system; firstly, malicious leaders can actively downgrade the processing speed of handling proposals, thereby diminishing the system’s overall performance. Secondly, they can determine the submission order of received requests, which can be fatal in specific decentralized financial systems. Additionally, external attackers can compromise the system’s stability by conducting DDoS attacks on leader nodes, frequently triggering view changes and potentially causing the system to lose liveness altogether. We present BFT Baxos, a more robust and resilient BFT consensus protocol that equips a BFT random exponential backoff mechanism to ensure each node has the egalitarian right to propose. Employing random exponential backoff as a replacement for leader election eliminates the potential malicious actions of Byzantine leaders and prevents external attackers from conducting targeted DDoS attacks on the leader node within systems. We implemented and evaluated our BFT Baxos prototype. Our results indicate that BFT Baxos exhibits good performance and scalability in low-concurrency scenarios. Additionally, we illustrated the functioning of BFT Baxos even in extremely adverse network conditions by subjecting it to random DDoS attacks. / BFT-konsensusalgoritmer är utformade för att säkerställa konsistensen i distribuerade system där noder kan agera godtyckligt, antingen på grund av fel eller avsiktliga skadliga handlingar. Dock är de flesta praktiska BFT-konsensusalgoritmerna baserade på ledare. I en fientlig nätverksmiljö uppvisar ledar-baserade BFT-konsensusalgoritmer sårbarheter och brist på motståndskraft. Bysantinska ledare kan utgöra en potentiell hot mot systemet; för det första kan skadliga ledare aktivt sänka behandlingshastigheten för hantering av förslag och därigenom minska systemets totala prestanda. För det andra kan de bestämma ordningen för inskickning av mottagna begäranden, vilket kan vara ödesdigert i vissa decentraliserade finansiella system. Dessutom kan externa angripare kompromettera systemets stabilitet genom att genomföra DDoS-attacker mot ledarnoder, vilket ofta utlöser vynändringar och potentiellt orsakar att systemet förlorar livskraft helt och hållet. Vi presenterar BFT Baxos, en mer robust och motståndskraftig BFT-konsensusprotokoll som utrustar en BFT slumpmässig exponentiell backoff-mekanism för att säkerställa att varje nod har rätten att föreslå på ett egalitärt sätt. Genom att använda slumpmässig exponentiell backoff som ett alternativ till ledarval eliminerar det inte bara möjliga skadliga handlingar från bysantinska ledare utan förhindrar även externa angripare från att genomföra riktade DDoS-attacker mot ledarnoden inom system. Vi implementerade och utvärderade vår BFT Baxos-prototyp. Våra resultat visar att BFT Baxos uppvisar god prestanda och skalbarhet i scenarier med låg samtidighet. Dessutom illustrerade vi funktionen av BFT Baxos även under extremt ogynnsamma nätverksförhållanden genom att utsätta den för slumpmässiga DDoS-attacker.