2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Cem Keskin ◽  
M. Pinar Mengüç

Abstract This paper introduces an innovative ventilation system that is capable of providing localized and customized thermal conditions in buildings. The system has diffusers with individually operable flaps that facilitate asymmetric air inlet to control air flow inside a room in an effective way. Moreover, the system involves distributed temperature sensors, a user interface, and a control unit that allows creation and management of “thermal subzones” within a room in accordance with the different preferences of occupants. As a specific case, the thermal management of a typical office in an academic building is considered. Both experimental and numerical studies were conducted to show that it is possible to achieve several degrees of temperature differences at different room locations in a transient and controllable fashion. The dynamic management of the temperature distribution in a room can prevent the waste of conditioning energy. It is shown that the system provides a practical and impactful solution by adapting to different user preferences (UPs) and by minimizing the resource use. In order to deal with the complexity of design, development, and operation of the system, it is considered as a cyber-physical-social system (CPSS). The core of the CPSS approach used here is an enhanced hybrid system modeling methodology that couples human dimension with formal hybrid dynamical modeling. Based on a coherent conceptual framing, the approach can combine the three core aspects, like cyber infrastructure, physical dynamics, and social/human interactions of modern building energy systems to accommodate the environmental challenges. Besides physics-based achievements (managing temperature distribution inside a room), the new AVS can also leverage user engagement and behavior change for energy efficiency in buildings by facilitating a new practice for occupants' interaction with heating, ventilation, and air conditioning (HVAC) system.


1989 ◽  
Vol 67 (2) ◽  
pp. 885-888 ◽  
Author(s):  
R. H. Morton

An important question in the study of the exercise response is the real or imaginary nature of the anaerobic threshold, and mathematical modeling techniques have been invoked to assist in resolving this issue. Two opposing views with competing data models recently published in this journal are criticized. One view suggests a segmented model with a discontinuous first derivative at the threshold. The other suggests a continuous model over the whole work load range, implying the anaerobic threshold to be imaginary. However, neither group of authors has devoted proper rigorous attention to the models they use. Had this been done, some of the divergence of opinion may have been avoided. Ideal data from an alternate segmented model that has a continuous first derivative at the threshold are considered for comparative purposes. This suggests that the log-log transformation method may well lead to improved detection of a threshold when one exists, although the estimates of the threshold value obtained are unreliable. Modeling methodology is a useful approach to the resolution of scientific issues, but there exist fundamental implications and alternatives that must be fully recognized.


2012 ◽  
Vol 37 (3) ◽  
pp. 2874-2884 ◽  
Author(s):  
José Miguel Pasini ◽  
Bart A. van Hassel ◽  
Daniel A. Mosher ◽  
Michael J. Veenstra

Author(s):  
Yingxu Wang ◽  
Cyprian F. Ngolah

The need for new forms of mathematics to express software engineering concepts and entities has been widely recognized. Real-time process algebra (RTPA) is a denotational mathematical structure and a system modeling methodology for describing the architectures and behaviors of real-time and nonrealtime software systems. This article presents an operational semantics of RTPA, which explains how syntactic constructs in RTPA can be reduced to values on an abstract reduction machine. The operational semantics of RTPA provides a comprehensive paradigm of formal semantics that establishes an entire set of operational semantic rules of software. RTPA has been successfully applied in real-world system modeling and code generation for software systems, human cognitive processes, and intelligent systems.


2009 ◽  
pp. 3340-3360
Author(s):  
Yingxu Wang ◽  
Cyprian F. Ngolah

The need for new forms of mathematics to express software engineering concepts and entities has been widely recognized. Real-time process algebra (RTPA) is a denotational mathematical structure and a system modeling methodology for describing the architectures and behaviors of real-time and nonreal-time software systems. This article presents an operational semantics of RTPA, which explains how syntactic constructs in RTPA can be reduced to values on an abstract reduction machine. The operational semantics of RTPA provides a comprehensive paradigm of formal semantics that establishes an entire set of operational semantic rules of software. RTPA has been successfully applied in real-world system modeling and code generation for software systems, human cognitive processes, and intelligent systems.


2000 ◽  
Author(s):  
Ipek Basdogan ◽  
Robert Grogan ◽  
Andy Kissil ◽  
Norbert Sigrist ◽  
Lisa Sievers

Abstract The Space Interferometer Mission (SIM) scheduled for launch in 2008, is one of the premiere missions in the Origins Program, NASA’s endeavor to understand the origins of the galaxies, of planetary systems around distant stars, and perhaps the origins of life itself. The precise tolerance required by the SIM instrument facilitates the investigation of many design options, trades, and methods for minimizing interaction between the actively controlled optics and the structure. One of the activities that addresses these technological challenges is the integrated modeling methodology development and validation at Jet Propulsion Laboratory (JPL). The methodology integrates structural, optical, and control system modeling into a common computational environment and enables end-to-end performance evaluation of complex optomechanical systems. This paper provides an overview of the integrated modeling methodology and introduces the most recent SIM Reference Design model. The SIM integrated model is used in system requirement trade studies and performance analyses to support the overall system design and ongoing error budget efforts. Optical performance in interferometry is typically measured in terms of optical pathlength difference (OPD) and differential wavefront tilt (DWT). This paper focuses on the OPD performance metric and investigates the OPD jitter resulting from reaction wheel assembly (RWA) disturbances. The RWA is the largest anticipated disturbance source on the spacecraft. Therefore, assessing the impact of the wheel disturbance frequency content and magnitude levels on the optical performance is essential for the success of the mission. Broadband and discrete frequency models of a reaction wheel are used to perform the disturbance analysis. The overall system design can benefit from such analysis results by identifying the critical regions in the frequency domain and decoupling the dynamics of the optical and structural components from the disturbance spectrum and the control bandwidth. The preliminary performance results show that the current SIM Reference Design meets the mission requirements with respect to RWA induced disturbances. However, some of the modeling assumptions and component models must be validated by experimental studies before the subsystem requirements are finalized.


Author(s):  
Alan A. Barhorst ◽  
Louis J. Everett

Abstract Mechanisms are inherently constrained devices. Combining flexibility with mechanisms usually requires using Lagrange multipliers to handle the constraints. The added algebraic or numerical tedium, associated with the Lagrange multipliers, is well documented. Presented in this paper is a technique for obtaining the minimal set of hybrid parameter differential equations for a constrained device. That is, the set of equations that inherently incorporate the constraints. The technique illustrated in this paper is a recently developed hybrid parameter multiple body (HPMB) system modeling methodology. The variational nature of the methodology allows rigorous equation formulation providing not only the complete nonlinear, hybrid differential equations, but also the boundary conditions. The methodology is formulated in the constraint-free subspace of the system’s configuration space, thus Lagrange multipliers are not needed for constrained systems, regardless of the constraint type (holonomic or nonholonomic). To evince the utility of the method, a flexible four bar mechanism is modeled. Particularly, the inversion of the slider crank found in the quick return mechanism. A comparison of Hamilton’s principle and the described technique, as they are applied to the mechanism, is included. It is shown that the same equations result from either method, but the new technique is much more concise, more efficiently handles the constraints, and requires less algebraic tedium.


Author(s):  
Sifat Islam ◽  
Ravi Shankar ◽  
Ankur Agarwal ◽  
Andrew Katan ◽  
Cyril-Daniel Iskander

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