153 research outputs found
Large Scale Optimization Problems for Central Energy Facilities with Distributed Energy Storage
On large campuses, energy facilities are used to serve the heating and cooling needs of all the buildings, while utilizing cost savings strategies to manage operational cost. Strategies range from shifting loads to participating in utility programs that offer payouts. Among available strategies are central plant optimization, electrical energy storage, participation in utility demand response programs, and manipulating the temperature setpoints in the campus buildings. However, simultaneously optimizing all of the central plant assets, temperature setpoints and participation in utility programs can be a daunting task even for a powerful computer if the desire is real time control. These strategies may be implemented separately across several optimization systems without a coordinating algorithm. Due to system interactions, decentralized control may be far from optimal and worse yet may try to use the same asset for different goals. In this work, a hierarchal optimization system has been created to coordinate the optimization of the central plant, the battery, participation in demand response programs, and temperature setpoints. In the hierarchal controller, the high level coordinator determines the load allocations across the campus or facility. The coordinator also determines the participation in utility incentive programs. It is shown that these incentive programs can be grouped into reservation programs and price adjustment programs. The second tier of control is split into 3 portions: control of the central energy facility, control of the battery system, and control of the temperature setpoints. The second tier is responsible for converting load allocations into central plant temperature setpoints and flows, battery charge and discharge setpoints, and temperature setpoints, which are delivered to the Building Automation System for execution. It is shown that the whole system can be coordinated by representing the second tier controllers with a smaller set of data that can be used by the coordinating controller. The central plant optimizer must supply an operational domain which constrains how each group of equipment can operate. The high level controller uses this information to send down loadings for each resource a group of equipment in the plant produces or consumes. For battery storage, the coordinating controller uses a simple integrator model of the battery and is responsible for providing a demand target and the amount of participation in any incentive programs. Finally, to perform temperature setpoint optimization a dynamic model of the zone is provided to the coordinating controller. This information is used to determine load allocations for groups of zones. The hierarchal control strategy is successful at optimizing the entire energy facility fast enough to allow the algorithms to control the energy facility, building setpoints, and program bids in real-time
Differential segregation in a cell-cell contact interface: the dynamics of the immunological synapse
Receptor-ligand couples in the cell-cell contact interface between a T cell and an antigen-presenting cell form distinct geometric patterns and undergo spatial rearrangement within the contact interface. Spatial segregation of the antigen and adhesion receptors occurs within seconds of contact, central aggregation of the antigen receptor then occurring over 1-5 min. This structure, called the immunological synapse, is becoming a paradigm for localized signaling. However, the mechanisms driving its formation, in particular spatial segregation, are currently not understood. With a reaction diffusion model incorporating thermodynamics, elasticity, and reaction kinetics, we examine the hypothesis that differing bond lengths (extracellular domain size) is the driving force behind molecular segregation. We derive two key conditions necessary for segregation: a thermodynamic criterion on the effective bond elasticity and a requirement for the seeding/nucleation of domains. Domains have a minimum length scale and will only spontaneously coalesce/aggregate if the contact area is small or the membrane relaxation distance large. Otherwise, differential attachment of receptors to the cytoskeleton is required for central aggregation. Our analysis indicates that differential bond lengths have a significant effect on synapse dynamics, i.e., there is a significant contribution to the free energy of the interaction, suggesting that segregation by differential bond length is important in cell-cell contact interfaces and the immunological synapse
Rural AI: Serverless-powered federated learning for remote applications
With increasing connectivity to support digital services in urban areas, there is a realization that demand for offering similar capability in rural communities is still limited. To unlock the potential of Artificial Intelligence (AI) within rural economies, we propose Rural AI—the mobilization of serverless computing to enable AI in austere environments. Inspired by problems observed in New Zealand, we analyze major challenges in agrarian communities and define their requirements. We demonstrate a proof-of-concept Rural AI system for cross-field pasture weed detection that illustrates the capabilities serverless computing offers to traditional federated learning
Sustainable development and well-being: a philosophical challenge
This paper aims at gaining a better understanding of the inherent paradoxes within sustainability discourses by investigating its basic assumptions. Drawing on a study of the metaphoric references operative in moral language, we reveal the predominance of the 'well-being = wealth' construct, which may explain the dominance of the 'business case' cognitive frame in sustainability discourses (Hahn et al. in Acad Manag Rev 4015:18–42, 2015a). We incorporate economic well-being variables within a philosophical model of becoming well (Küpers in Cult Organ 11(3):221–231, 2005), highlighting the way in which these variables consistently articulate a combination of 'objective' and 'subjective' concerns. We then compare this broad understanding of well-being with the metaphors operative in the sustainable development discourse and argue that the sustainability discourse has fallen prey to an overemphasis on the 'business case'. We proceed to draw on Georges Bataille to challenge the predominance of these value priorities and to explore which mindshifts are required to develop a more comprehensive understanding of what is needed to enable 'sustainable development'
Lessons from the Subprime Meltdown
This paper uses Hyman P. Minsky's approach to analyze the current international financial crisis, which was initiated by problems in the American real estate market. In a 1987 manuscript, Minsky had already recognized the importance of the trend toward securitization of home mortgages. This paper identifies the causes and consequences of the financial innovations that created the real estate boom and bust. It examines the role played by each of the key playersincluding brokers, appraisers, borrowers, securitizers, insurers, and regulatorsin creating the crisis. Finally, it proposes short-run solutions to the current crisis, as well as longer-run policy to prevent it (a debt deflation) from happening again
Gastric Outlet Obstruction as the Initial Presentation of Upper Tract Urothelial Carcinoma
GOO is often the first sign of advanced upper gastrointestinal neoplasms. The most common neoplasms associated with GOO include gastric, pancreatic, and biliary tract cancers. Urinary tract urothelial carcinoma has been a rarely documented cause of GOO
Gastric outlet obstruction as the initial presentation of upper tract urothelial carcinoma
GOO is often the first sign of advanced upper gastrointestinal neoplasms. The most common neoplasms associated with GOO include gastric, pancreatic, and biliary tract cancers. Urinary tract urothelial carcinoma has been a rarely documented cause of GOO
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