One of tasks in analyzing acoustics of coupled spaces is to evaluate different decay times from double-slope decay characteristics of Schroeder decay functions using measured room impulse responses. Traditionally howe...
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ISBN:
(纸本)9781604234848
One of tasks in analyzing acoustics of coupled spaces is to evaluate different decay times from double-slope decay characteristics of Schroeder decay functions using measured room impulse responses. Traditionally however, identification of double- or multiple- sloped decay in room impulse response measurement has been considered very challenging. We apply Bayesian probabilistic analysis methods to cope with the demanding tasks in estimating multiple decay times from Schroeder decay functions. Using experimentally measured data in real coupled spaces, this paper discusses estimation of decay times and related parameters within Bayesian framework.
Nested Sampling is a method introduced by Skilling as a bayesian sampling method for model selection and parameter estimation. We present a view of Nested Sampling as an approximate method for computing the Lebesgue I...
Nested Sampling is a method introduced by Skilling as a bayesian sampling method for model selection and parameter estimation. We present a view of Nested Sampling as an approximate method for computing the Lebesgue Integral of a function. We then apply Nested Sampling to the problem of estimating the decay order and decay time as applied to the acoustics of coupled rooms.
In buildings, windows and glazed facades are often the weak link in protecting the interior from exterior noise. Since passive means for improving the Sound Transmission Loss (STL) of glazed facades are very expensive...
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In buildings, windows and glazed facades are often the weak link in protecting the interior from exterior noise. Since passive means for improving the Sound Transmission Loss (STL) of glazed facades are very expensive and are effective only at high frequencies, an active controller that increases the STL in the low frequency range is an attractive approach to reducing the noise level in buildings with glazed facades, guaranteeing the performance required by the 89/106/CEE European Directive, which made protection against noise a compulsory requirement for buildings. Several kinds of active control system of Sound Transmission were recently studied, whose two main applications are known as Active Noise Control (ANC) and Active Structural Acoustic Control (ASAC) systems. This paper concerns the second approach: it is based on the reduction of structural vibration, through the use of actuators bonded on the vibrating surfaces, driven by an automated control system, whose task is minimizing those vibrations, and consequently, radiated sound. A technological study aimed at choosing a suitable solution for the integration of such automated control systems in buildings with glazed facades is studied, and future research developments are planned.
A Vertical seismic isolation system using disk spring is designed. The experiment is conducted in dynamic character and it is analyzed using the time-history analysis method. The maximum acceleration and the displacem...
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A Vertical seismic isolation system using disk spring is designed. The experiment is conducted in dynamic character and it is analyzed using the time-history analysis method. The maximum acceleration and the displacement response between story and story are provided. The differences between the isolated building and the non-isolated building are discussed. It is proven that the disk spring device can work efficiently in vertical seismic isolation.
Courtyard and building geometry are crucial aspects to achieve efficient natural ventilation and indoor thermal comfort in a compact urban environment. In this paper, first, a comparison between different geometries o...
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ISBN:
(纸本)9953418691
Courtyard and building geometry are crucial aspects to achieve efficient natural ventilation and indoor thermal comfort in a compact urban environment. In this paper, first, a comparison between different geometries of courtyards in terms of wind flow characteristics and indoor air speed is performed based on the validation of Computational Fluid Dynamics (CFD) simulations with 2D published wind-tunnel experiments. Second, assessment of thermal comfort is made inside a number of selected dwelling's rooms facing different courtyard geometries. It was confirmed that rooms with cross ventilation have higher indoor air speeds as well as a cooler thermal condition than with single-side ventilation. The courtyard dimensions, the position of the room and the orientation are important aspects influencing both the indoor air speed and thermal comfort.
The characteristics of a vibration system suppressed with an impact damper are investigated, where impact damper is simplified using spring and viscous damping. The analysis begins with the derivation of simple, yet a...
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The characteristics of a vibration system suppressed with an impact damper are investigated, where impact damper is simplified using spring and viscous damping. The analysis begins with the derivation of simple, yet accurate approximations for free vibration response of the structure-absorber system. An analytical theory is developed for the optimal values of the impact damper damping and initial displacement in a single-of-freedom structure. The relation between coefficient of restitution and damping ratio is obtained. The research shows that the effective reduction of the vibration of the vibration response doesn't depend on the number of impacts but primarily on the type of collision that the impact mass collides with the main mass face-to-face. Results also show that the clearance of an effective impact damper should be smaller than twice of the initial displacement of the main mass of the vibration system if the system is stimulated by an initial displacement only. The theory is generalized to continuous structures. An example of an impact damper in a rotating cantilever beam demonstrates that the impact dampers are suitable for attenuating the impulse response of structures unconditional stabilization without the requirement of the accuracy of the modal information.
Successful design is usually a collaboration of individuals from more than one discipline. To address this important future work environment, student interdisciplinary design projects were created. For the past severa...
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Successful design is usually a collaboration of individuals from more than one discipline. To address this important future work environment, student interdisciplinary design projects were created. For the past several years, teams of students from the first year engineering Design Graphics course in the College of engineering and students from the second year Industrial Design Studio in the College of architecture and Urban Studies have teamed together to pursue design-build projects. However, there has heretofore been no effort to assess the effectiveness of this collaboration nor have there been any projects addressing significant human needs particularly in a global context. This semester the focus of the interdisciplinary project was on assistive technology applicable in third world countries. This work was an opportunity to assess quantitative and qualitative differences in process and products of homogeneous and interdisciplinary teams as well as the impact of human centered design projects
Consequent to abandoning the use of halon in total flooding gas protection systems, clean agents are used for fire control. It is difficult to carry out so many physical experiments on assessing their performance. Num...
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Consequent to abandoning the use of halon in total flooding gas protection systems, clean agents are used for fire control. It is difficult to carry out so many physical experiments on assessing their performance. Numerical modeling is an effective tool and computational fluid dynamics (CFD) is a good method for studying the interaction with the fire-induced flow. Thermal radiation is a key point in modeling such process and the importance of it will be discussed in this paper.
Wind tunnel experiments were conducted on a series of two-dimensional perforated plates normal to an air stream to study the characteristics of unsteady wake pressures and to ascertain the parameters amongst which a c...
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Wind tunnel experiments were conducted on a series of two-dimensional perforated plates normal to an air stream to study the characteristics of unsteady wake pressures and to ascertain the parameters amongst which a certain level of correlation can be established. The velocity ranged from 5 m/s to 15 m/s in the present study. The pressure field gets significantly modified as the perforation level increases. The present study is concerned with three plates with perforation level of 0%, 25% and 35%. There appears to be a correlation between the maximum normalized value of the RMS pressure fluctuation levels, base pressure and the perforation level of the normal plate.
The intermittent property of Photovoltaic (PV) system requires some sort of energy storage or supplement to supply the similarly intermittent load demand. It can be achieved by connecting the PV electricity to the uti...
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The intermittent property of Photovoltaic (PV) system requires some sort of energy storage or supplement to supply the similarly intermittent load demand. It can be achieved by connecting the PV electricity to the utility grid, or by energy storage device like battery. Either of these means would, to certain extent, affect the electrical network stability if not designed properly. An accurate supply and load forecast would also be a useful tool in ensuring the system stability and reliability when the supply and load can be predicted with higher accuracy. Furthermore, artificial intelligence could play an important role here when the controllable supply and loads can be regulated to promote energy efficiency and system stability. With the precise knowledge of the efficiency characteristics of different PV technologies, including those newly commercialised ones, the simulation of dynamic model of energy output from a building integrated photovoltaic (BIPV) system can be achieved as an important part of the building energy management system (BEMS) in providing necessary control mechanism for the energy demand within the building. When the effect of exposure to weather on the system performance is considered as well, the dynamic model shall be able to adjust itself over time when the system components are degrading. This concept of feedback loop will be adopted as the basis of the dynamic model to realize its adaptive ability to learn through previous experience.
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