Recent advances in specialized hardware for solving optimization problems such quantum computers, quantum annealers, and CMOS annealers give rise to new ways for solving real-word complex problems. However, given current and near-term hardware limitations, the number of variables required to express a large real-world problem easily exceeds the hardware capabilities, thus hybrid methods are usually developed in order to utilize the hardware. In this work, we advocate for the development of hybrid methods that are built on top of the frameworks of existing state-of-art heuristics, thereby improving these methods. We demonstrate this by building on the so called Louvain method, which is one of the most popular algorithms for the Community detection problem and develop and Ising-based Louvain method. The proposed method outperforms two state-of-the-art community detection algorithms in clustering several small to large-scale graphs. The results show promise in adapting the same optimization approach to other unsupervised learning heuristics to improve their performance.
Designing more sustainable urban infrastructure is an essential topic in practice and research. While many have tried to address this challenge by focusing on sustainability of either supply or demand in a single infrastructure system, few studies have integrated the decisions for both supply and demand across several infrastructure. This paper proposes a novel method to design and optimize the hourly demand and supply of integrated energy and water system in an urban district for environmental and economic sustainability. This modular framework concurrently designs the optimal building mix of an urban district and the systems supplying the district with wastewater treatment, cooling, heating, and electricity. The model is tested on a sample neighborhood from San Francisco, California, with 21 building prototypes, 32 combined heating and power engines, 16 chillers, and 3 wastewater treatment systems (a central treatment plant and two decentralized membrane-based systems). The results of this study show that the median values of normalized life-cycle cost, social cost of carbon, annual energy demand, and annual wastewater production of the integrated designs of water-energy system are, respectively, 20, 75, 8, and 20% lower than those of the traditional segregated designs. The results also demonstrate the economic and environmental viability of using decentralized advanced treatment in urban areas when energy system, wastewater treatment, and building mix are designed together.
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