Browsing by Subject "Energy consumption"

Now showing 1 - 4 of 4
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    A Case Study of Safe and Cost-Effective Hospital HVAC Strategies
    (2022-08-02) Caesar, Jeffrey; Ray, Matthew Veto; Koo, Dan; Dalir, Hamid
    The pressures of healthcare facilities to keep patients safe while also maintaining financial viability have been felt in recent years amongst industry leaders. The impacts COVID has had on patient safety and planning has in any way fast-tracked patient safety progress, but certainly at a financial cost. As hospital leaders and facility leaders attempt to grapple with these realities, a facility's operating strategy that addresses both safety and cost should be employed. The below study aims to solve two issues facing hospital facility leadership in regards to the facilities’ HVAC system. The first issue is how to decrease energy consumption and operating expenses in light of industry pressures to improve the financial outlook and secondly, how to increase patient safety as a direct result of COVID-19 realities. Increasing safety and ultimately flexibility can many times increase costs, so utilizing the most appropriate and tested techniques that follow patient safety protocols will be necessary. The importance of this study cannot be understated. As with any healthcare system, improving patient outcomes are at the heart of the industry and especially in light of our recent pandemic. The fundamental question as to how facilities can keep patients safer while simultaneously reducing energy consumption is a tough question to answer, but manageable due to both recent industry experience and up-to-date research on the topic. The methodology will be to conduct a straightforward cost benefit analysis that takes into account both patient safety and energy consumption. The first step will be to gather baseline data for Lutheran Hospital’s HVAC system to gauge current system performance vs. benchmarked performance. Next, the data will inform us as to what strategies to implement to both curb costs and increase patient safety. The third step will be to implement those strategies where possible and measure their benefits. Lastly, a conclusion will be made as to what long-term solutions will be most useful to both this hospital and the other hospitals within Lutheran Health Network.
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    Effect of geometric, material and operational parameters on the steady-state belt response for flat belt-drives
    (2015-05) Yildiz, Cagkan; Wasfy, Tamer M.; Tovar, Andres; El-Mounayri, Hazim A.
    This thesis presents a comprehensive study of the effects of material, geometric and operational parameters on flat belt-drives steady-state belt stresses, belt slip, and belt-drive efficiency. The belt stresses include: belt rubber shear, normal, axial and lateral stresses; reinforcements tension force; and tangential and normal belt-pulley contact stresses. Belt slip is measured using the driven over driver pulleys’ angular velocity ratio. Each parameter was varied over a range to understand its impact on the steady-state belt-drive response. The material parameters studied are belt axial stiffness and damping, belt bending stiffness and damping, and belt-pulley friction coefficient. The geometric parameters studied are pulley center distance, pulleys diameter ratio, and belt thickness. The operational parameters studied are the driver pulley angular velocity and the driven pulley opposing torque (load). A high-fidelity flexible multibody dynamics parametric model of a two-pulley belt-drive system was created using a commercial multibody dynamics code. In the model the belt’s rubber matrix is represented using three-dimensional brick elements and the belt’s reinforcements are represented using one dimensional beam elements at the top surface of the belt. An asperity-based Coulomb friction model is used for the friction forces between the pulley and belt. The pulleys are modeled as rigid bodies with a cylindrical contact surface. The equations of motion are integrated using an explicit solution procedure. Unlike prior models which use one-dimensional truss or beam elements for the belt, the present model uses a three-dimensional belt model which introduces the effect of the thickness of the belt rubber matrix (modeled using brick elements). This enables a more accurate prediction of the belt stresses and slip than prior models. This thesis resolves in more details the complex stick-slip friction behavior of an axially flexible belt coupled with the shear effects of a flexible rubber cushion and at the same time shows the effect of the main system parameters on this stick-slip behavior. Some of the important conclusions of the thesis include: (1) the driver pulley has two distinct contact zones - a negative traction zone and a positive traction zone - while only one traction zone is present over the driven pulley; (2) the width of the negative traction zone on the driver pulley increases with the belt-pulley coefficient of friction and decreases with the belt axial stiffness; (3) the maximum belt tension and normal contact stress occur on the driver pulley and increase with the belt thickness, belt axial stiffness, and coefficient of friction; (4) belt-drive energy efficiency increases with the belt axial stiffness, and decreases with belt thickness, belt bending damping, belt operating speed, and operating torque load. The belt-drive modeling methodology presented in this thesis which enables accurate prediction of the belt stresses and slip can in turn be used to more accurately predict the fatigue life, wear life, and energy efficiency of belt-drives.
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    Energy-Efficient Device Selection in Federated Edge Learning
    (IEEE, 2021-07) Peng, Cheng; Hu, Qin; Chen, Jianan; Kang, Kyubyung; Li, Feng; Zou, Xukai; Computer and Information Science, School of Science
    Due to the increasing demand from mobile devices for the real-time response of cloud computing services, federated edge learning (FEL) emerges as a new computing paradigm, which utilizes edge devices to achieve efficient machine learning while protecting their data privacy. Implementing efficient FEL suffers from the challenges of devices’ limited computing and communication resources, as well as unevenly distributed datasets, which inspires several existing research focusing on device selection to optimize time consumption and data diversity. However, these studies fail to consider the energy consumption of edge devices given their limited power supply, which can seriously affect the cost-efficiency of FEL with unexpected device dropouts. To fill this gap, we propose a device selection model capturing both energy consumption and data diversity optimization, under the constraints of time consumption and training data amount. Then we solve the optimization problem by reformulating the original model and designing a novel algorithm, named E2DS, to reduce the time complexity greatly. By comparing with two classical FEL schemes, we validate the superiority of our proposed device selection mechanism for FEL with extensive experimental results.
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    Modeling and analysis of an air handling unit to improve energy efficiency
    (2015-08) Li, Jing; Chen, Jie; Goodman, David; Razban, Ali
    The Air Handling Unit (AHU), which serves the entire basement of Engineering and Technology (ET) building on IUPUI campus, had constant set points of discharge air temperature and supply air static pressure. Two reset schedules were investigated to determine which was the best control strategy to minimize energy consumption of the AHU. In this research, a gray box model was established to create the baseline of energy consumption with constant set points and predict the energy savings using two di↵erent reset schedules. The mathematical model was developed in Engineering Equation Solver (EES). It was validated using two sets of sub hourly real time data. The model performance was evaluated employing Mean Absolute Percentage Error (MAPE) and Root Mean Square Deviation (RMSD). Additionally, uncertainty propagation identified outside air temperature, supply airflow rate and return air temperature were the key parameters that had an impact in overall energy consumption. Discharge air temperature was reset based on return air temperature (RA-T) with a linear reset schedule from March 4 to March 7. Static pressure was reset based on the widest open Variable Air Volume (VAV) box damper from March 20 to March 23. Results indicated that 17% energy savings was achieved using discharge air temperature reset while the energy consumption reduced by 7% using static pressure reset.