Статті в журналах з теми "Damped room"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Damped room.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Damped room".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Gottfried, David S., Eric S. Peterson, Asim G. Sheikh, Jiaqian Wang, Ming Yang, and Joel M. Friedman. "Evidence for Damped Hemoglobin Dynamics in a Room Temperature Trehalose Glass." Journal of Physical Chemistry 100, no. 29 (January 1996): 12034–42. http://dx.doi.org/10.1021/jp9609489.
Повний текст джерела
2
Liu, L. Y., J. Y. Li, and X. J. Yin. "Experimental Study on the Performance of Constrained Damped Rail Vibration Reduction." Noise & Vibration Worldwide 42, no. 10 (November 2011): 9–14. http://dx.doi.org/10.1260/0957-4565.42.10.9.
Повний текст джерелаАнотація:
To study the vibration reduction performance of damped rail, we take the standard rail and labyrinth constrained damped rail as the study target. By testing the vibration performance of both standard rail and labyrinth constrained damped rail in an anechoic room, we use the time-domain analysis to study the vibration changes with time passing. The results showed that: the labyrinth constrained damped rail vibration can effectively reduce the vibration amplitude and duration. Under the radial impact load, compared to the standard rail, vibration acceleration attenuation of the labyrinth constrained damped rail is 5% −19%, time of vibration and attenuation greater than 94%; under the axial impact load, compared to the standard rail, vibration acceleration attenuation of the labyrinth constrained damped rail is 9% −21%, time of vibration and attenuation greater than 92%. The results have provided an experimental basis for the design of new constrained damped rail.
3
Pham Vu, Thach, and Hervé Lissek. "Low frequency sound field reconstruction in a non-rectangular room using a small number of microphones." Acta Acustica 4, no. 2 (2020): 5. http://dx.doi.org/10.1051/aacus/2020006.
Повний текст джерелаАнотація:
An accurate knowledge of the sound field distribution inside a room is required to identify and optimally locate corrective measures for room acoustics. However, the spatial recovery of the sound field would result in an impractically high number of microphones in the room. Fortunately, at low frequencies, the possibility to rely on a sparse description of sound fields can help reduce the total number of measurement points without affecting the accuracy of the reconstruction. In this paper, the use of Greedy algorithm and Global curve-fitting techniques are proposed, in order to first recover the modal parameters of the room, and then to reconstruct the entire enclosed sound field at low frequencies, using a reasonably low set of measurements. First, numerical investigations are conducted on a non-rectangular room configuration, with different acoustic properties, in order to analyze various aspects of the reconstruction frameworks such as accuracy and robustness. The model is then validated with an experimental study in an actual reverberation chamber. The study yields promising results in which the enclosed sound field can be faithfully reconstructed using a practically feasible number of microphones, even in complex-shaped and damped rooms.
4
Yan, Feng, Robin Wilson, and Peter Rutherford. "Prediction of acoustic transmission in heavily damped system using hybrid Ray-Tracing-SEA method." Noise Control Engineering Journal 68, no. 3 (May 20, 2020): 226–36. http://dx.doi.org/10.3397/1/376819.
Повний текст джерелаАнотація:
Classic statistical energy analysis mainly deals with the energy transmission of system with relatively low damping. With the application of passive damping treat- ments, one of the fundamental assumptions in SEA, i.e., a diffused field, tends to fail. The energy attenuation along transmission path becomes so significant that there may exist large energy level difference within one structural component. In light of this, this study proposes to use a hybrid ray-tracing-SEA method to predict the acoustic transmission in heavily damped system. Heavily damped structural compo- nents are treated as â–œcoupling elementsâ–? instead of normal â–œsubsystems.â–? The en- ergy transmission from one structural element to a connected structural element through the edge can be represented by using certain number of point sources and assuming each point source radiates certain number of acoustic rays. By tracing the travelling history of each ray, the energy attenuation along the travelling path can be achieved. With the information of energy input and energy attenuation, the equivalent coupling loss factors can be computed. By rebuilding a hybrid ray- tracing-SEA model, the energy level differences between different subsystems can be determined. Numerical validation of the ray tracing algorithm is conducted by comparing the calculated coupling loss factor with normal SEA method. Numerical study of a one-room system is given. The room is assumed to consist of six homoge- neous concrete plates and the analysis assumes no coupling between in-plan and out- plane waves. Comparisons between classic and hybrid method show that when a small number of the structural components are heavily damped, classic SEA gives similar results with the hybrid method because the prediction errors tend to cancel with each other and the transmission is dominated by paths that are not damped. With the increasing number of damped elements, SEA tends to underestimate the energy level difference.
5
Bisnette, Jesse B., Adam K. Smith, Jeffrey S. Vipperman, and Daniel D. Budny. "Active Noise Control Using Phase-Compensated, Damped Resonant Filters." Journal of Vibration and Acoustics 128, no. 2 (July 16, 2005): 148–55. http://dx.doi.org/10.1115/1.2149393.
Повний текст джерелаАнотація:
An active noise control device called active noise absorber or ANA, which is based upon damped, resonant filters is developed and demonstrated. It is similar to structural positive position feedback (PPF) control, with two exceptions: (1) Acoustic transducers (microphone and speaker) cannot be truly collocated, and (2) the acoustic actuator (loudspeaker) has significant dynamics. The speaker dynamics can affect performance and stability and must be compensated. While acoustic modal control approaches are typically not sought, there are a number of applications where controlling a few room modes is adequate. A model of a duct with speakers at each end is developed and used to demonstrate the control method, including the impact of the speaker dynamics. An all-pass filter is used to provide phase compensation and improve controller performance and permits the control of nonminimum phase plants. A companion experimental study validated the simulation results and demonstrated nearly 8 dB of control in the first duct mode. A multi-modal control example was also demonstrated producing an average of 3 dB of control in the first four duct modes.
6
Karakonstantis, Xenofon, and Efren Fernandez Grande. "Sound Field Reconstruction in Rooms with Deep Generative Models." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 5 (August 1, 2021): 1527–38. http://dx.doi.org/10.3397/in-2021-1864.
Повний текст джерелаАнотація:
The characterization of Room Impulse Responses (RIR) over an extended region in a room by means of measurements requires dense spatial with many microphones. This can often become intractable and time consuming in practice. Well established reconstruction methods such as plane wave regression show that the sound field in a room can be reconstructed from sparsely distributed measurements. However, these reconstructions usually rely on assuming physical sparsity (i.e. few waves compose the sound field) or trait in the measured sound field, making the models less generalizable and problem specific. In this paper we introduce a method to reconstruct a sound field in an enclosure with the use of a Generative Adversarial Network (GAN), which s new variants of the data distributions that it is trained upon. The goal of the proposed GAN model is to estimate the underlying distribution of plane waves in any source free region, and map these distributions from a stochastic, latent representation. A GAN is trained on a large number of synthesized sound fields represented by a random wave field and then tested on both simulated and real data sets, of lightly damped and reverberant rooms.
7
Kuvykin, Yu А., A. N. Olkhovskiy, V. V. Suprunyuk, and I. N. Sokolov. "A Method for Determining Frequency Response of Microphones in Unmuffled Laboratory Room Using Wideband Signal Excitement." Herald of the Bauman Moscow State Technical University. Series Instrument Engineering, no. 4 (137) (December 2021): 169–87. http://dx.doi.org/10.18698/0236-3933-2021-4-169-187.
Повний текст джерелаАнотація:
The paper introduces a method for determining the frequency response of microphones using a broadband excitation signal. The method is based on time deiay spectrometry and uses the recursive filter of the Goertzel algorithm and additional sliding complex weighted averaging under conditions burdened by sound reverberation. A combination of field and pressure measurements was used to minimize the effect of reflections during measurements. Relying on the algorithm, we developed software for post-processing the measurement results when determining the frequency response of microphones in an unmuffled laboratory room. Furthermore, we assembled a research measuring complex and experimentally tested the developed method and software determining the methodical error in the frequency response of microphones using a broadband excitation signal. The developed method and software are recommended for determining the frequency response of measuring microphones by the field in unmuffled reverberating laboratory rooms without auxiliary equipment, such as a damped chamber and a small-volume chamber, provided the practical recommendations given in the research are taken into consideration
8
Skočík, Petr, Martin Pospíšilík, Vojtěch Křesálek, and Milan Adámek. "Indirect Measurement of Shielding Effectiveness of an Enclosure for a Security Camera." Measurement Science Review 21, no. 1 (February 1, 2021): 39–46. http://dx.doi.org/10.2478/msr-2021-0006.
Повний текст джерелаАнотація:
Abstract This paper presents the results of our experiment, which consisted in measurement of the shielding effectiveness of a camera enclosure that was designed and constructed in order to increase the susceptibility of a camera against external electromagnetic fields. All activities, from defining of requirements to final design and measurements, were performed in the Laboratory of Electromagnetic Compatibility at the Faculty of Applied Informatics of Tomas Bata University in Zlín. The hereby described approach allowed to utilize standardized laboratory equipment that is normally used for device susceptibility test to radiated electric field. The measurement was made inside a semi-anechoic room additionally damped by absorbers placed on its floor. When configuring the experiment, relevant EMC standards EN 55016 and EN 61000-4-3 were considered. Although the uncertainty tolerances, allowed by the relevant standards, were quite high for measurements in such rooms, the results obtained by the experiment matched the theoretical expectations quite satisfactorily.
9
Putra, Azma, Al Munawir, W. M. F. W. Mohamad, and J. I. Mohammad. "The Effect of Direct Field Component on a Statistical Energy Analysis (SEA) Model." Applied Mechanics and Materials 471 (December 2013): 279–84. http://dx.doi.org/10.4028/www.scientific.net/amm.471.279.
Повний текст джерелаАнотація:
Statistical Energy Analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. The structure is divided into subsystems where the energy in each of the subsystem is assumed to be reverberant. This study investigates the application of SEA model in a 'damped' acoustic space where the direct field component from the sound source dominates the total sound field rather than a diffuse field in a reverberant space which the SEA model assumption is based on. A measurement was conducted in a scaled room divided into two acoustic spaces separated by a partition with an opening. Absorbent materials were installed on the room walls and the power injection technique was implemented to obtain the coupling loss factor (CLF) of the system. It is found that correction of the direct field component from the subsystem energy improves the prediction of the CLF of the system.
10
Evans, Jack B. "Pneumatically Isolated Inertia Base with Active Damping for a Transmission Electron Microscope (TEM)." Journal of Low Frequency Noise, Vibration and Active Control 28, no. 3 (September 2009): 169–83. http://dx.doi.org/10.1260/026309209790252590.
Повний текст джерелаАнотація:
Low frequency sound and vibration affects the performance and use of electron microscopes, by disturbing the stability and resolution of the specimen's video image. A transmission electron microscope (TEM) addition was proposed to an existing research suite that had three scanning electron microscopes (SEM). The TEM, which is very heavy, rather tall and has a high center of gravity, is very sensitive to floor vibrations. This case study presents sources of disturbing vibration with spectrum measurements. The designs of the microscope room and an actively damped, pneumatic vibration isolation system are discussed. Post-installation vibration measurement results to validate performance are presented in spectral analysis charts versus criteria. Drawings and photographs illustrate the installation.
11
Chuamuangphan, Pipat, C. Chuamuangphan, and Kamchai Treechairusme. "The Superconducting Magnetic Properties of YBCO Effect on the Inductance of Coil." Advanced Materials Research 93-94 (January 2010): 668–71. http://dx.doi.org/10.4028/www.scientific.net/amr.93-94.668.
Повний текст джерелаАнотація:
The effect of the magnetic properties of YBCO superconductors on the inductance of coil were studied in order to the dependence on temperature of effective penetration depth and the variation potential difference for damped oscillation in RLC series circuit. In this work, The samples of YBa2Cu3-xAgxO7- were prepared by solid state reaction in air at 950 ๐C for 24 hr. serves as the core of solenoids. The inductance of solenoids changes up with the increasing of temperature from boiling point of liquid nitrogen (77 K) to room temperature had been measured. Then we calculated to the effective penetration depth. We found that there were increase correspond with the increasing of temperature and the critical temperature decreased and then increased with the increase in Ag2O concentration of x = 0.1 and 0.2 , respectively. The variation potential difference for damped oscillation in RLC series circuit. We found that the decreasing of amplitude per cycle of the samples at superconducting state larger than those at normal state and phases shift in the damping oscillattion of RLC circuit at superconducting state are less than that at normal state, discussed as in inductance, the magnetic flux entering through the samples at superconducting state are less than that at normal state.
12
Bhattarai, Shankar, Ji-Seong Go, Hongrae Kim, and Hyun-Ung Oh. "Experimental Validation of a Highly Damped Deployable Solar Panel Module with a Pogo Pin-Based Burn Wire Triggering Release Mechanism." International Journal of Aerospace Engineering 2020 (December 14, 2020): 1–14. http://dx.doi.org/10.1155/2020/8829515.
Повний текст джерелаАнотація:
In this present work, a highly damped deployable solar panel module was developed for application in the 3 U CubeSat. The solar panel proposed herein is effective in guaranteeing the structural safety of solar cells under a launch environment owing to the superior damping characteristics achieved using multilayered stiffeners with viscoelastic acrylic tapes. A holding and release action of the solar panel was achieved by a new version of spring-loaded pogo pin-based burn wire triggering mechanism. A demonstration model of high-damping solar panel assembly was fabricated and tested to validate the effectiveness of the design. The holding and release mechanism achieved using a pogo pin was functionally tested through solar panel deployment tests under ambient room temperature and a thermal vacuum environment. The design effectiveness and structural safety of the solar panel module were validated through qualification-level launch and in-orbit environment tests.
13
Papalou, A., and S. F. Masri. "Performance of Particle Dampers Under Random Excitation." Journal of Vibration and Acoustics 118, no. 4 (October 1, 1996): 614–21. http://dx.doi.org/10.1115/1.2888343.
Повний текст джерелаАнотація:
An experimental and analytical study is made of the performance of particle dampers under wide-band random excitation. A small model, provided with a nonlinear auxiliary mass damper, was used to investigate the major system parameters that influence the performance of particle dampers: total auxiliary mass ratio, particle size, container dimension, and the intensity and direction of the excitation. It is shown that properly designed particle dampers, even with a relatively small mass ratio, can considerably reduce the response of lightly damped structures. An approximate analytical solution, which is based on the concept of an equivalent single unit-impact damper, is presented. It is shown that the approximate solution can provide an adequate estimate of the root-mean-square response of the randomly excited primary system when provided with a particle damper that is operating in the vicinity of its optimum range of parameters.
14
Hebb, J. P., E. G. Cravalho, and M. I. Flik. "Thermal Radiation Absorption in Doped Semiconductors Due to Direct Intersubband Transitions." Journal of Heat Transfer 117, no. 4 (November 1, 1995): 948–54. http://dx.doi.org/10.1115/1.2836315.
Повний текст джерелаАнотація:
This work proposes an engineering model for thermal radiation absorption due to direct intersubband transitions in doped semiconductors, which are excitations of bound electrons in the infrared spectral region. An existing quantum-mechanical approach is to model these transitions as a continuum of damped harmonic oscillators. This study modifies this approach to yield a more effective method for determining the optical constants of doped semiconductors. The room-temperature absorptance spectra of p-type GaAs samples with dopant concentrations from 8 × 1017 to 1 × 1020 cm-3 are measured using a Fourier transform–infrared spectrometer in the spectral region from 1.5 to 25 μm. The fitting of these spectra using the proposed model combined with the Drude and Lorentz models provides the optical constants and the dependence of the adjustable parameters on dopant concentration. The measured and fitted spectra agree closely. Potential applications of the model are semiconductor process control and infrared detector design.
15
Salehi, Mohsen, Hooshang Heshmat, and James F. Walton. "On the Frictional Damping Characterization of Compliant Bump Foils." Journal of Tribology 125, no. 4 (September 25, 2003): 804–13. http://dx.doi.org/10.1115/1.1575774.
Повний текст джерелаАнотація:
High-speed rotor systems use either fluid film or rolling element bearing supports, depending upon their design and operating constraints. Regardless of bearing type used, these systems require specific bearing and support stiffness and damping characteristics to achieve the desired stable and low vibration operation. Building upon the technology of thin metallic corrugated bump foils presently used in a particular class of film riding hydrodynamic bearings, a novel corrugated bump foil damped mount is introduced which provides stiffness and damping for application with rolling element bearings. These damping elements are capable of operating at elevated temperatures where implementation of conventional squeeze film dampers is ruled out. The frictional damping results from micro-slip motions between the bump foils and the mating surfaces. A semi-empirical model, based on a one degree of freedom model was developed in which damping is replaced by an equivalent frictional force in order to gain insight into the dynamic friction coefficient of the individual damping element interfaces. Experimental results, obtained in the form of hysteresis loops were compared to the developed model with good agreement. The variation in damping and dynamic coefficient of friction was found to be dependent primarily upon three factors: vibration frequency, amplitude of motion and applied static load. These parameters were tested within the range of 50–1400 Hz, 2.54–12.7 micron and 45–135 N, respectively. The tests were conducted at room and 538°C ambient temperatures under both dry and vapor phase lubricated conditions. Using the resulting empirical data, several bearing dampers were designed, built and tested in a small, high-speed gas turbine engine simulator. The tested novel foil dampers were capable of operating reliably under extremely high levels of shaft imbalance (i.e., 320 times greater than the air bearing supported with specification of 0.0002 oz-in) even while operating at temperatures to 560°C. These results show the great potential for wide application of these dampers on gas turbine engines and high-speed rotating machinery.
16
Hu, Yanzhu, Song Wang, Zhaoyang Wang та Yixin Zhang. "The Research on Information Representation of Φ-OTDR Distributed Vibration Signals". Journal of Sensors 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/6020645.
Повний текст джерелаАнотація:
This paper mainly focuses on the representable problem of Φ-OTDR distributed vibration signals. The research included a signal extraction part and a signal representation part. Firstly, in order to extract the better Φ-OTDR signal, the time-domain data should be fully preserved. The 2D-TESP method is used to extract data in this paper. There are 29 characters in the traditional TESP method. The characters’ number is reduced from 29 to 13 and the characters’ dimension is expanded from 1 to 2 in the 2D-TESP method. Secondly, in order to represent Φ-OTDR signal better, the characteristics of Φ-OTDR data and damped vibration signals are combined in the paper. The EMD method and the NMF method are combined to form the new method in the paper. Some parameters in the proposed method are optimized and adjusted by GA method. After Φ-OTDR data is represented by the proposed method, there is excellent performance both on the length dimension and on the time dimension. Lastly, some experiments are carried out according to the physical truth in this paper. The experiments are carried out in the semianechoic room. The methods of the paper have better performance. The methods are proved to be effective through these experiments.
17
Ostos, O. J., and Y. A. Zhuk. "Thermomechanical problem on vibration of a viscoelastic rubberlike rod under dynamic loading." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 1 (2019): 146–49. http://dx.doi.org/10.17721/1812-5409.2019/1.33.
Повний текст джерелаАнотація:
The problem on vibration of a viscoelastic rod under dynamic load at one of its ends is considered. The external loading has a signfficant influence on the dynamic characteristics of the material. By using the complex moduli, the problem on vibration of the viscoelastic rod was solved. The complex shear and Young's moduli of a rubberlike material should exhibit the same dependence on frequency. The properties of a rubberlike material was applied. The temperature influence is associated both with the Newton boundary conditions and dissipative heating. The dissipative function is expressed in terms of deformations. The frequencies of high-damping materials occur at or near frequencies that are normally of interest in vibration problems at room temperature. For solving the problem a finite element model was applied. Using this model, qualitative analysis of the influence of dynamic load and dissipative heating on the resonant vibrations of viscoelastic rod is performed. According to the theory of viscoelasticity an analysis of the results was done. The reliability of the values of frequencies for the first resonances was checked. The numerical results qf the problem on vibration of a viscoelastic cylindrical rod under dynamic load at one of its end by the general thermomechanical laws on vibration in damped mechanical systems were obtained and investigated. Distribution of the temperature of dissipative heating along the rod axis is analyzed.
18
Prasher, Ravi S., and Patrick E. Phelan. "A Scattering-Mediated Acoustic Mismatch Model for the Prediction of Thermal Boundary Resistance." Journal of Heat Transfer 123, no. 1 (July 12, 2000): 105–12. http://dx.doi.org/10.1115/1.1338138.
Повний текст джерелаАнотація:
Solid-solid thermal boundary resistance Rb plays an important role in determining heat flow, both in cryogenic and room-temperature applications, such as very large scale integrated circuitry, superlattices, and superconductors. The acoustic mismatch model (AMM) and the related diffuse mismatch model (DMM) describe the thermal transport at a solid-solid interface below a few Kelvin quite accurately. At moderate cryogenic temperatures and above, Rb is dominated by scattering caused by various sources, such as damage in the dielectric substrates and formation of an imperfect boundary layer near the interface, making Rb larger than that predicted by AMM and DMM. From a careful review of the literature on Rb, it seems that scattering near the interface plays a far more dominant role than any other mechanism. Though scattering near the interface has been considered in the past, these models are either far too complicated or are too simple (i.e., inaccurate) for engineering use. A new model, called the scattering-mediated acoustic mismatch model (SMAMM), is developed here that exploits the analogy between phonon and radiative transport by developing a damped wave equation to describe the phonon transport. Incorporating scattering into this equation and finding appropriate solutions for a solid-solid interface enable an accurate description of Rb at high temperatures, while still reducing to the AMM at low temperatures, where the AMM is relatively successful in predicting Rb.
19
Zhang, Xiaoyi, Weijun Gao, Yanxue Li, Zixuan Wang, Yoshiaki Ushifusa, and Yingjun Ruan. "Operational Performance and Load Flexibility Analysis of Japanese Zero Energy House." International Journal of Environmental Research and Public Health 18, no. 13 (June 24, 2021): 6782. http://dx.doi.org/10.3390/ijerph18136782.
Повний текст джерелаАнотація:
ZEHs (Zero Energy House) featuring energy-efficient designs and on-site renewable integration are being widely developed. This study introduced Japanese ZEHs with well-insulated thermal envelopes and investigated their detailed operational performances through on-site measurements and simulation models. Measurement data show that ZEHs effectively damped the variation of indoor air temperature compared to conventional houses, presenting great ability to retain inside heat energy, and are expected to potentially deliver energy flexibility as a virtual thermal energy storage medium. We developed a simplified thermal resistance–capacitance model for a house heating system; response behaviors were simulated under various scenarios. Results compared the variations of indoor temperature profiles and revealed the dependence of load flexibility on the building’s overall heat loss performance. We observed that overall heat loss rate played a crucial role in building heat energy storage efficiency; a well-insulated house shortened the heat-up time with less energy input, and extended the delayed period of indoor temperature under intermittent heating supply; a high set-point operative temperature and a low ambient temperature led to lower virtual thermal energy storage efficiency. The preheating strategy was simulated as an effective load-shifting approach in consuming surplus PV generation; approximately 50% of consumed PV generation could be shifted to replace grid import electricity for room heating during the occupied period.
20
Satria, E., L. Son, M. Bur, and M. Dzul Akbar. "Finite Element Analysis to Determine Stiffness, Strength, and Energy Dissipation of U-Shaped Steel Damper under Quasi-Static Loading." International Journal of Automotive and Mechanical Engineering 18, no. 3 (September 21, 2021): 9042–50. http://dx.doi.org/10.15282/ijame.18.3.2021.16.0693.
Повний текст джерелаАнотація:
In seismic areas, the application of structural dampers becomes compulsory in the design of buildings. There are various types of dampers, such as viscous elastic dampers, viscous fluid dampers, friction dampers, tune mass dampers, yielding/ metallic dampers, and magnetic dampers. All damper systems are designed to protect structural integrities, control damages, prevent injuries by absorbing earthquake energy, and reduce deformation. This paper is a part of research investigating the behaviour of the U-shaped steel damper (as one type of metallic damper) that can be applied to the buildings in seismic areas. The dampers are used as connections between the roof and supporting structure, with the two general purposes. The first is to control the displacement of roof under an earthquake, and the second is to absorb seismic energy through the plasticity of some parts in dampers. If a strong earthquake occurs, the plasticity will absorb the seismic energy; therefore, heavy damage could be avoided from the roof’s mainframes. In this paper, several models of U-shaped steel dampers are introduced. Several parameters, such as elastic stiffness, maximum strength, and energy dissipation, are determined under two conditions. Firstly, static analysis of the proposed damper under variation of U-steel plate configurations, searching the model with more significant energy dissipation. Secondly, static analysis of the unsymmetrical and symmetrical damper under different loading directions. An in-house finite element program that involves both geometrical and material nonlinearities is developed as a problem solver. A quasi-static lateral loading is given to each model until one cycle of the hysteresis curve is reached (in the displacement range between -20 mm to +20 mm). The above parameters are calculated from the hysteresis curve. From the results, the behaviour of the U-steel damper can be described as follows. Firstly, increasing the energy dissipation in the lateral direction can be done by increasing the lateral stiffness of the damper. However, it can reduce the maximum elastic deformation of the damper. Secondly, under the random direction of loading, a symmetrical shape can increase the energy dissipation of the damper.
21
Verma, Arpit, Vidit Khandelwal, Anil Singh Baghel, and Sanjay Kumar Chourasiya. "Risk assessment of priesthood as an occupation in the religious city of India." International Journal Of Community Medicine And Public Health 7, no. 10 (September 25, 2020): 3887. http://dx.doi.org/10.18203/2394-6040.ijcmph20204016.
Повний текст джерелаАнотація:
Background: Ujjain being a holy city with 327 registered temples, large numbers of people are indulged in priesthood as an occupation. Priests are more vulnerable for health-related problems as priesthood demands some characteristic working environment, i.e. closed, damped, smoky, noisy and crowded workplace. Aim of the study was to assess workplace environment of the priest along with occurrence of occupational injuries.Method: A cross-sectional study done on registered Hindu priests. Total sample size was 440. Simple random sampling was done. Self-designed, pre-tested and semi-structured questionnaire including parameters like problem felt, job satisfaction, stress felt, working hours and occupational injuries were used for data collection by personal interview.Results: 256 (58.2%) study participants encounter occupational injury. Problems felt at their workplace were- overcrowding 259 (58.9%), improper drainage system 48 (10.9%), unsafe drinking water 44 (10%), air pollution 25 (5.7%), inappropriate waste disposal 24 (5.5%), poor ventilation 24 (5.5%), no sick-room 8 (1.8%) and no toilets 8 (1.8%). Out of 440 study participants 132 (30.0%) were not satisfied with their job due to-less financial support 96 (22%), long duration of working hours 20 (4%) and stressful relations with co-workers 16(4%). 136 (30.9%) of study participants were stressed at their workplace. Statistically significant (p<0.05) association was seen between occurrence of occupational injuries and age, job satisfaction, working hours (overtime) and stress felt.Conclusion: Most of the problems felt by study participants along with occupational injuries and job dissatisfaction occurred due to poor financial support, long working hours and stressful relations with co-workers.
22
Ayanladun, Chris Abiodun, and Sunday Ayoola Oke. "Optimisation of Water Absorption Parameters of Bagasse, Cocoa Pod Husk and Guinea Fowl Feather Reinforced Hybrid Epoxy Composites using Taguchi Method." Journal of Applied Science & Process Engineering 8, no. 1 (April 30, 2021): 786–805. http://dx.doi.org/10.33736/jaspe.3015.2021.
Повний текст джерелаАнотація:
Particulate waste of bagasse, cocoa pod husk and guinea fowl feathers may be adopted to fabricate epoxy composites due to their properties of biodegradability, lightweight and cheapness. However, most research has excluded the combination of these reinforcements while the optimisation behaviour of the reinforced composites at room temperature water absorption process is not known. To fill this knowledge gap, this paper aims to analyse issues related to optimisation of the mentioned reinforced composites considering Taguchi’s L25 orthogonal array, the smaller the better signal-to-noise criterion and remodelling of signal-to-noise ratio after the exponential smoothening structure for optimisation. The experiment considered 25% reinforcement blends to 75% epoxy resin. But the 25% reinforcement had five formulations among the component reinforcements. The experiment, using tap water, was conducted for 216 days with measurement intervals random. The response table yielded A5B5C4, indicating 158 experimental days, 12.29g of weight gained by the drained composites, and 7.32g of weight gained by composites damped in 190ml of water. The revised response table that has been influenced by the exponential smoothening method yielded A5B5C5, interpreted as 158 days of experiments, 12.29g of weight gained by the drained composites, and 7.44g of weight gained by composites dumped in 190ml of water. Using the damping factors from 0.05 to 1, different combinations as optimal parameters were obtained, assuring the investigator that the method is feasible. Thus, the optimisation assessment could provide a new method of combining the reinforcement to enhance the composite development process using waste.
23
Han, Miao, Richard Twizeyimana, and Hongkai Du. "Experimental Study on Mechanical Properties of Small Size Viscoelastic Damper." E3S Web of Conferences 237 (2021): 03028. http://dx.doi.org/10.1051/e3sconf/202123703028.
Повний текст джерелаАнотація:
Long span roofs are very likely to oscillate when subjected to wind load that can lead to structure fatigue and endanger structures safety. Dampers have been used for long time to dissipate wind and earthquake induced energy in structures. This research work aims to present experimental study of small size viscoelastic damper that can be installed in truss of long span roof. Small size viscoelastic dampers that can be used to dissipate wind induced energy in large span roof structure need to be tested to know their performance behavior and mechanical properties at different loading amplitudes and frequencies. A kind of viscoelastic dampers were manufactured and tested under horizontal cyclic loads. Resistance and deformation of the damper were measured to study the viscoelastic damper properties dependence on frequency and amplitude. Mechanical properties including shear storage modulus, shear loss modulus, loss factor and energy dissipation are studied. Experimental results show that the small size damper’s mechanical properties are significantly related to its loading frequency and amplitude. The energy dissipation capacity of the damper was stable under different loading frequency and amplitude.
24
Yu, Guo Jun, Xi Xi Wen, Yu Liu, and Bo Su. "Preparation and Study of a Type of Magneto-Rheological Materials Used in Vibration Control of Space Grid Structure." Applied Mechanics and Materials 865 (June 2017): 181–87. http://dx.doi.org/10.4028/www.scientific.net/amm.865.181.
Повний текст джерелаАнотація:
A type of Magneto-Rheological Materials (MRMs) was prepared. The off-state viscosity and the shear stress of the MRMs were characterized and studied by an advanced rotational rheometer system. A kind of Self-Decoupling Magneto-rheological (SDMR) damper was established based on these MRMs. An intellectual isolation system for grid structures was obtained by integrating SDMR damper and isolation device. The seismic whiplash effect of the top bent frame column and space grid roof of the hydropower plant could be reduced. Furthermore, the half stable increment method was proposed as the semi-active strategy. The results indicated that the SDMR dampers used at the grid roof supports setting plate rubber bearings can significantly improve the vibration performance and energy dissipation structure roof isolation system in different seismic intensity. In addition, these SDMR dampers can effectively reduce the lateral slippage of the plate rubber, so as to avoid failure or damage of the isolation system because of the transfinite horizontal displacements. Compared with the conventional damper only in case of multiple earthquakes, the damping force and adjustable multiple of this SDMR damper have better adaptability, and this SDMR damper provides a higher safety factor.
25
Cipra, Dale O. "Damper root ring." Journal of the Acoustical Society of America 127, no. 4 (2010): 2710. http://dx.doi.org/10.1121/1.3396217.
Повний текст джерела
26
Zainuriah, Hassan, Sha Shiong Ng, G. L. Chew, F. K. Yam, Mat Johar Abdullah, M. Roslan Hashim, Kamarulazizi Ibrahim, and M. E. Kordesch. "Growth and Properties of GaN/Si Heterojunction." Materials Science Forum 480-481 (March 2005): 531–36. http://dx.doi.org/10.4028/www.scientific.net/msf.480-481.531.
Повний текст джерелаАнотація:
Gallium nitride (GaN) is a highly promising wide band gap semiconductor with applications in high power electronic and optoelectronic devices. Thin films of GaN are most commonly grown in the hexagonal wurtzite structure on sapphire substrates. Growth of GaN onto silicon substrates offers a very attractive opportunity to incorporate GaN devices onto silicon based integrated circuits. Although direct epitaxial growth of GaN films on Si substrates is a difficult task (mainly due to the 17% lattice mismatch present), substantial progress in the crystal quality can be achieved using a buffer layer. A full characterization of the quality of the material needs to be assessed by a combination of different techniques. In this work, a detailed characterization study of GaN thin film grown on Si(111) with AlN buffer layer by low pressure metalorganic chemical vapor deposition (LP-MOCVD) was carried out. Post deposition analysis includes scanning electron microscopy (SEM), x-ray diffraction (XRD), Hall and infrared (IR) spectroscopy techniques. The IR spectra were compared to the calculated spectra generated with a damped single harmonic oscillator model. Through this method, a complete set of reststrahlen parameters (such as ε∞, S, wTO, γ) of the GaN epilayer were obtained. Our results show that the GaN film has a single crystalline structure. Current-voltage characteristics (I-V) of this GaN/Si heterojunction were measured at room temperature. Rectification behavior was observed for this anisotype heterojunction. The electrical characteristics of Ni Schottky barriers on this unintentionally doped n-type film were also investigated. The barrier height of Ni/GaN Schottky barriers has been determined to be 0.93 eV by I-V measurement.
27
Villaverde, Roberto. "Roof Isolation System to Reduce the Seismic Response of Buildings: A Preliminary Assessment." Earthquake Spectra 14, no. 3 (August 1998): 521–32. http://dx.doi.org/10.1193/1.1586013.
Повний текст джерелаАнотація:
A roof isolation system is proposed as a means to reduce the detrimental effect of earthquakes in buildings. This roof isolation system entails the insertion of flexible laminated rubber bearings between a building's roof and the columns that support it, and the addition of viscous dampers connected between the roof and the rest of the building. The properties and dimensions of the rubber bearings and viscous dampers are selected in a way that makes the roof, bearings, and dampers form a highly damped vibration absorber. Presented also is a comparative study with a simple five-story steel building under a strong earthquake ground motion that is carried out to assess the effectiveness of the proposed system. In this comparative study, it is found that the roof isolation scheme reduces the floor displacements and interstory drifts of the analyzed building by as much as 83 percent. On the basis of these results and in view of its simplicity, it is concluded that the proposed roof isolation system has the potential to become a practical and effective way to reduce earthquake damage in buildings.
28
Meissner, Mirosław. "Acoustic Behaviour of Lightly Damped Rooms." Acta Acustica united with Acustica 99, no. 5 (September 1, 2013): 845–47. http://dx.doi.org/10.3813/aaa.918663.
Повний текст джерела
29
Lye, Michael, and Tom Walley. "Haemodynamic Responses in Young and Elderly, Healthy Subjects during Ambient and Warm Head-up Tilt." Clinical Science 94, no. 5 (May 1, 1998): 493–98. http://dx.doi.org/10.1042/cs0940493.
Повний текст джерелаАнотація:
1. Postural hypotension is common in elderly people and is usually multifactorial in origin. In young subjects increased ambient temperature is associated with postural symptoms. We hypothesized that such increases in skin temperature due to the use of bed clothes might contribute to nocturnal postural hypotension in the elderly. We therefore studied haemodynamic responses to head-up tilt in healthy elderly and young subjects, with and without passive heating induced by covering with blankets. 2. Nine young (28.7 ± 1.5 years; mean ± S.E.M.) and nine elderly (71.9 ± 1.8 years) subjects were studied. All had been carefully screened to exclude factors likely to affect responses to tilt. All subjects underwent a standard head-up tilt procedure at ambient room temperature while haemodynamic responses were monitored. The subjects were then covered in blankets for 55 min and the tilt repeated. Skin temperature before the second tilt had increased from approximately 32.5 °C to approximately 35.2 °C (P < 0.001). 3. The elderly subjects maintained higher blood pressures throughout both tilts (P < 0.001) and both groups showed similar qualitative responses to tilt. Supine heart rates were higher in the elderly group (P < 0.01) with a tendency to increase more in the young group in response to tilt, especially while warm (P = 0.370). Stroke volumes and cardiac indices were consistently higher in the young group who showed larger changes during both head-up tilts. In both groups the haemodynamic responses to ambient and warm tilt were essentially the same. 4. Healthy elderly subjects, who are carefully screened to exclude individuals with cardiovascular pathology, respond to head-up tilt in the same qualitative fashion as young subjects. Quantitative responses in older subjects are ‘damped’. Short-term natural body warming does not impair the reflexes in young or old subjects.
30
Anan’in, V. M., B. A. Kalin, V. V. Novikov, and A. V. Sumarokova. "Identification of relaxation maxima of internal friction in the Zr – Nb alloy after nitriding, oxidation in air, and in situ carburization." Physics and Chemistry of Materials Treatment, no. 6 (2021): 26–34. http://dx.doi.org/10.30791/0015-3214-2021-6-26-34.
Повний текст джерелаАнотація:
The internal friction method was used to study the behavior of the Zr – 1 wt. % Nb alloy after oxidation in air, nitriding in an atmosphere of technical nitrogen, and in situ carburization during measurements. In this case, carbon was deposited on the samples during measurements due to thermal decomposition of vapors of diffusion oil. The pressure in the system was about 10–2 Pa. The temperature dependence of the logarithmic decrement of damped bending vibrations with a frequency of 2.2 – 2.4 Hz was measured on specimens in the form of a rectangular plate 22 × 8 × 0.3 mm in size. The measurements were carried out at a constant heating rate of about 4 K/min from room temperature to 700 – 750 °C. The obtained temperature dependences of internal friction were divided into partial maxima using a special program. The program determines the temperatures of the relaxation maxima and calculates the effective activation energy using the Werth — Marx formula. The internal friction spectra in successive measurements on one sample changed due to the diffusion redistribution of the alloy components. The parameters of the relaxation maxima for carbon (153 – 159 kJ/mol), oxygen (203 – 207 kJ/mol) and nitrogen (235 – 238 kJ/mol) in the alloy under study, depending on the experimental conditions, have been established. Grain-boundary (Gb) impurity maxima due to these impurities were also found. The following activation energies were obtained: 173 – 179 kJ/mol for C-Gb, 216 – 219 kJ/mol for O-Gb and 222 – 229 kJ/mol for N-Gb. Impurity grain-boundary maxima associated with carbon, oxygen, and nitrogen were observed in each series of measurements. The activation energy of the grain-boundary maxima proper decreases monotonically from 202.4 to 194.5 kJ/mol in a series with oxidation in air (experiments 711 – 715), and remains about 200 kJ/mol in nitrided samples.
31
Kopylov, Semen, Zhaobo Chen, and Mohamed AA Abdelkareem. "Back-iron design-based electromagnetic regenerative tuned mass damper." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 234, no. 3 (June 14, 2020): 607–22. http://dx.doi.org/10.1177/1464419320932350.
Повний текст джерелаАнотація:
Implementation of tuned mass dampers is the commonly used approach to avoid excessive vibrations in civil engineering. However, due to the absence of the compact dimension, there are still no practical applications of the tuned mass dampers in automotive industry. Meanwhile, recent investigations showed the benefit of utilizing a tuned mass damper in a vehicle suspension in terms of driving comfort and road holding. Thus, the current investigation aimed to explore a novel compact dimension tuned mass damper, which can provide both sufficient vibration mitigation and energy harvesting. This paper presents a prototype of a back-iron-based design of an electromagnetic regenerative tuned mass damper. The mathematical model of the tuned mass damper system was developed and has been validated by the experimental results of the tuned mass damper prototype implemented in a protected mass test-bench. The indicated results concluded that the attenuation performance dramatically deteriorated under random excitations and a reduction in the root-mean-square acceleration of 18% is concluded compared to the case with undamped tuned mass damper. Under harmonic excitations, the designed tuned mass damper prototype is able to reduce the peak acceleration value of the protected structure by 79%. According to the experimental results, the designed tuned mass damper prototype revealed a peak regenerative power of 0.76 W under a harmonic excitation of 8.1 Hz frequency [Formula: see text]m amplitude. Given the simulated random road profiles from C to E, the back-iron electromagnetic tuned mass damper indicated that root-mean-square harvested power from 0.6 to 6.4 W, respectively.
32
Olechowska, Marcelina, Artur Nowoświat, Jan Ślusarek, and Mateusz Latawiec. "The influence of the distribution of sound absorbing materials on the estimation of reverberation time in rooms." E3S Web of Conferences 49 (2018): 00078. http://dx.doi.org/10.1051/e3sconf/20184900078.
Повний текст джерелаАнотація:
Reverberation time in rooms depends on many factors, e.g. cubature, surface of envelopes, sound absorption coefficient of materials used for the construction of the envelopes, geometry of rooms or the distribution of sound absorbing materials. The arrangement of sound absorbing materials in rooms has an impact on the dispersion of acoustic field, yet theoretical calculation models do not take into account this impact. According to these models, regardless of the arrangement of sound absorbing materials, the reverberation time in a room will remain unchanged. The present paper investigates the above problem by means of computer simulations. For the needs of the simulation, three rooms with different dimensions were adopted, i.e. type 'p' - a cuboidal room with a square base, type 'd' - a cuboidal room (with one side of the 'p' room lengthened), type 'w' - a cuboidal room (with the height of the room lengthened 'p'). During the simulation, the way of acoustic field dispersion was being changed and its influence on the reverberation time in the rooms was being determined. The authors investigated two situations. The first one involved a non-dampened room, in which the sound absorbing material was being arranged differently. The second one involved a welldampened room, and the dispersion of sound field was analyzed depending on the location of the reflecting material.
33
Kim, Jinkoo, and Seeun An. "Optimal distribution of friction dampers for seismic retrofit of a reinforced concrete moment frame." Advances in Structural Engineering 20, no. 10 (December 15, 2016): 1523–39. http://dx.doi.org/10.1177/1369433216683197.
Повний текст джерелаАнотація:
This study investigated the story-wise optimal distribution of friction dampers to effectively reduce the seismic response of a reinforced concrete structure designed without considering seismic load. To this end, a genetic algorithm process was applied and the results were compared with those obtained by simple intuitive method based on story drift. The seismic performance of the model structure with optimally positioned friction dampers was evaluated by nonlinear static and dynamic analyses. The analysis results showed that compared with the system without friction dampers, the maximum roof displacement and the inter-story drift ratio were reduced by about 30% and 40%, respectively, after installation of the dampers. In comparison with the intuitive method of installation, the genetic algorithm provided an efficient solution for optimum damper distribution with less amount of friction damper.
34
Zhang, Peng, Jinwei Jiang, and Guangtao Lu. "Low Temperature Influence on the Behavior of Viscoelastic Layer of the Pounding Tuned Mass Damper." Materials 12, no. 23 (December 1, 2019): 3986. http://dx.doi.org/10.3390/ma12233986.
Повний текст джерелаАнотація:
In previous studies, the pounding tuned mass damper (PTMD) has been successfully demonstrated to mitigate the undesired vibration of a variety of structures at room temperature. The advantages of the PTMD over the traditional tuned mass damper (TMD) has been verified through theoretical analysis and experimental investigations. However, the PTMD relies on an impact layer made of viscoelastic material to improve its vibration control performance and robustness against detuning effect. The energy dissipation of the viscoelastic material can be affected by the changes of environmental temperature. Therefore, this paper aims to study the impact damping behavior of the viscoelastic material in the low temperature environment of the sea bed where the PTMD is expected to control vibrations of subsea pipelines. The experimental apparatus fabricated in the previous study to generate and measure the lateral impact was housed inside a refrigerator. The experimental results indicate that the pounding stiffness decreased whereas the energy dissipation increased in the low temperature environment. Moreover, an impact fatigue test was also performed in the low temperature environment and compared with the room temperature case. Experimental results from a previous study show that the viscoelastic material was damaged after 36,000 cycles of impacts in the room temperature and a cyclic hardening–softening process was observed. However, in the low temperature environment, the viscoelastic material was damaged after 50,000 cycles of impacts and the cyclic hardening–softening process was not observed. As the impact cycle grew, the pounding stiffness decreased from 53,000 N/m1.5 to 17,000 N/m1.5 and the energy dissipation increased from 46.12 J/m per cycle to 65.4 J/m per cycle.
35
Shih, Ming-Hsiang, and Wen-Pei Sung. "Seismic Resistance and Parametric Study of Building under Control of Impulsive Semi-Active Mass Damper." Applied Sciences 11, no. 6 (March 10, 2021): 2468. http://dx.doi.org/10.3390/app11062468.
Повний текст джерелаАнотація:
When high-rise buildings are shaken due to external forces, the facilities of the building can be damaged. A Tuned Mass Damper (TMD) can resolve this issue, but the seismic resistance of TMD is exhausted due to the detuning effect. The Impulsive Semi-Active Mass Damper (ISAMD) is proposed with fast coupling and decoupling at the active joint between the mass and structure to overcome the detuning effect. The seismic proof effects of a high-rise building with TMD and ISAMD were compared. The numerical analysis results indicate that: (1) the reduction ratio of the maximum roof displacement response and the mean square root of the displacement reduction ratio of the building with the ISAMD were higher than 30% and 60%, respectively; (2) the sensitivity of the efficiency index to the frequency ratio of the ISAMD was very low, and detuning did not occur in the building with the ISAMD; (3) to achieve stable seismic resistance of the ISAMD, its frequency ratio should be between 2 and 4; (4) the amount of displacement of the control mass block of the ISAMD can be reduced by enhancing the stiffness of the auxiliary spring of the ISAMD; and (5) the proposed ISAMD has a stable control effect, regardless of the earthquake distance.
36
Partamayasa, I. Wayan Gede, I. Ketut Gede Suhartana, and I. Wayan Supriana. "Perancangan Sistem Pengaturan Suhu Ruangan Otomatis Berbasis Mikrokontroler." JELIKU (Jurnal Elektronik Ilmu Komputer Udayana) 8, no. 1 (August 9, 2019): 95. http://dx.doi.org/10.24843/jlk.2019.v08.i01.p12.
Повний текст джерелаАнотація:
A server room is a room that is used to store servers, network communication devices such as routers and switches, and other operational related devices. Server rooms that have high temperatures and humidity will affect the performance of all devices, so the temperature and humidity of the server room must be maintained so that the device is not easily damaged. So from that, the company needs to implement a standard to protect the performance of the devices stored in it. To overcome this problem a device was developed that can automatically control and monitor temperature and humidity. The system will be built using temperature and humidity sensors that are used to monitor the temperature of the room, the condition of the room temperature and humidity of the room will be displayed through a website that can be accessed through the internet network.
37
Kapulla, R., G. Mignot, S. Paranjape, M. Andreani, and D. Paladino. "Large Scale Experiments Representing a Containment Natural Circulation Loop during an Accident Scenario." Science and Technology of Nuclear Installations 2018 (November 1, 2018): 1–12. http://dx.doi.org/10.1155/2018/8989070.
Повний текст джерелаАнотація:
The assessment of hydrogen release, distribution, and mitigation measures in the containment of a nuclear power plant is increasingly based on code calculations. These calculations require state-of-the-art experiments to benchmark the codes against them. Two of these experiments are presented in this paper. These experiments were conducted in the PANDA facility (Switzerland) in the framework of the OECD/NEA HYMERES project. The experiments consider natural circulation flow in a two-room type containment where flow loops can form between the inner and the outer zones. During normal operation these zones are separated and in the case of an accident they become either connected by the opening of rupture disks, convective foils, and dampers or connected by bursting of doors and opening of other connections between compartments. For the experiments considered here one lower PANDA-vessel represents the steam generator (SG) tower and the inaccessible area whereas the other vessel represents the outer room area. The lower vessels are isolated from one another except for a small aperture that represents the damper. The two upper vessels—representing the containment dome—are connected to the lower vessels through tubes. The scenario consisted of four phases. In phase 1, a high steam mass flow rate was injected in the vessel representing the SG tower. After the relaxation phase 2, helium (representing hydrogen) was injected in the same vessel (phase 3). Finally in phase 4 no active interventions were done until the end of the test. Two tests were conducted to evaluate the developing helium transport by the natural circulation flow: one with and one without damper (by closing the aperture). The results showed that a two-room containment (TRC) mixing scenario can be well represented with the PANDA facility. It is found that, with the mixing damper open, a global natural circulation loop develops over all four vessels, whereas with closed damper the natural circulation loop is established only between the three vessels representing the inner zone and the upper dome. It is shown that the presence of the damper has a strong effect on the resulting helium content in the inner zone with 3 times less helium at the end of the test compared with the configuration without damper. The formation of a stable helium stratification in the upper vessels was observed in the presence of the open damper.
38
Kushibe, Atsumichi, Yorinobu Takigawa, Kenji Higashi, Kazuo Aoki, Koichi Makii, and Toshiaki Takagi. "Application of High-Strain-Rate Superplastic Zn-Al Alloy to Seismic Dampers and its Optimised Shape Design." Materials Science Forum 551-552 (July 2007): 583–90. http://dx.doi.org/10.4028/www.scientific.net/msf.551-552.583.
Повний текст джерелаАнотація:
As a new damping material, the authors first developed a Zn-22wt.%-Al eutectoid alloy with ultra-fine grains exhibiting superplasticity at room temperature by means of thermomechanical controlling processes (TMCPs). The Zn-Al alloy has a few advantages such as low work-hardening rate and high ductility over a conventional seismic damping material, for instance, a low-yield-point steel. In addition, Zn-Al alloys are environment-conscious because of no harmful metal like Pb. However, when Zn-Al alloys are subjected to plastic deformation, since its work hardening is small, plastic deformation proceeds locally so that required absorption energy cannot be sufficiently obtained, and local fracture and local deformation instability can take place easily, which is the intrinsic characteristic of superplastic materials. Therefore we attempted to develop a shear panel type, a brace type damper for tall buildings and a bending type damper for Japanese wooden houses using FEM analysis in order to minimize localized strain and local deformation and to determine the optimum shape for this Zn-Al superplastic seismic damper. As a result, an ecological and high-energy absorption seismic dampers, so-called “maintenance-free seismic damper,” was successfully developed.
39
Oance, Ionuț-Sergiu, and Sunai Gelmambet. "Effect of Number and Position of Rotational Friction Dampers on Seismic Response of Steel Frame." Ovidius University Annals of Constanta - Series Civil Engineering 21, no. 1 (December 1, 2019): 99–104. http://dx.doi.org/10.2478/ouacsce-2019-0011.
Повний текст джерелаАнотація:
Abstract This paper deals with effect of number and position of friction dampers on seismic response of 2D steel frame. For the present study four structures with six storeys are subjected to a time history analysis. For each story are using two, four and six friction dampers with different positions keeping slip load and stiffness constant. To study the effect of number and position of dampers in structures, are analysed the time period, top roof displacement, maximum base shear and percentage energy dissipated in accordance with energy induced in the frame. The results indicate that number and placement of damper affects the structural response. A large number of dampers do not always lead to best benefit in terms of energy dissipation.
40
Shimotsuma, Yasuhiko, Masaaki Sakakura, Kiyotaka Miura, Jiarong Qiu, Peter G. Kazansky, Koji Fujita, and Andkazuyuki Hirao. "Application of Femtosecond-Laser Induced Nanostructures in Optical Memory." Journal of Nanoscience and Nanotechnology 7, no. 1 (January 1, 2007): 94–104. http://dx.doi.org/10.1166/jnn.2007.18008.
Повний текст джерелаАнотація:
The femtosecond laser induced micro- and nanostructures for the application to the three-dimensional optical data storage are investigated. We have observed the increase of refractive index due to local densification and atomic defect generation, and demonstrated the real time observation of photothermal effect after the femtosecond laser irradiation inside a glass by the transient lens (TrL) method. The TrL signal showed a damped oscillation with about an 800 ps period. The essential feature of the oscillation can be reproduced by the pressure wave creation and propagation to the outward direction from the irradiated region. The simulation based on elastodynamics has shown that a large thermoelastic stress is relaxed by the generation of the pressure wave. In the case of soda-lime glass, the velocity of the pressure wave is almost same as the longitudinal sound velocity at room temperature (5.8 μm/ns). We have also observed the localized photo-reduction of Sm3+ to Sm2+ inside a transparent and colorless Sm3+-doped borate glass. Photoluminescence spectra showed that some the Sm3+ ions in the focal spot within the glass sample were reduced to Sm2+ ions after femtosecond laser irradiation. A photo-reduction bit of 200 nm in three-dimensions can be recorded with a femtosecond laser and readout clearly by detecting the fluorescence excited by Ar+ laser (λ = 488 nm). A photo-reduction bit can be also erased by photo-oxidation with a cw Ar+ laser (λ = 514 5 nm). Since photo-reduction bits can be spaced 150 nm apart in a layer within glass, a memory capacity of as high as 1 Tbit can be achieved in a glass piece with dimensions of 10 mm × 10 mm × 1 mm. We have also demonstrated the first observation of the polarization-dependent periodic nanostructure formation by the interference between femtosecond laser light and electron acoustic waves. The observed nanostructures are the smallest embedded structures ever created by light. The period of self-organized nanostructures can be controlled from ∼140 to 320 nm by the pulse energy and the number of irradiated pulses. Furthermore, we have also observed the self-assembled sub-wavelength periodic structures created in silica glass by femtosecond pulses on the plane of the propagation of light.
41
Izzat, N., I. J. Craddock, G. S. Hilton, and C. J. Railton. "Analysis and realization of low-cost damped screened rooms." Computer Standards & Interfaces 20, no. 6-7 (March 1999): 482. http://dx.doi.org/10.1016/s0920-5489(99)91086-3.
Повний текст джерела
42
Izzat, N., I. J. Craddock, G. S. Hilton, and C. J. Railton. "Analysis and realisation of low-cost damped screened rooms." IEE Proceedings - Science, Measurement and Technology 145, no. 1 (January 1, 1998): 1–7. http://dx.doi.org/10.1049/ip-smt:19981650.
Повний текст джерела
43
Chien, Chia Shang Chang, Wei Yuan Wang, Ging Huei Huang, and Yen Po Wang. "Seismic Testing of In-Plane Flexural Damper in Arched-Shape." Advanced Materials Research 1065-1069 (December 2014): 1117–20. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.1117.
Повний текст джерелаАнотація:
This study proposes an innovative displacement-dependent metallic yielding damper for seismic protection of building structures. The damper is designed to deform inelastically under in-plane flexural bending and becomes energy-dissipative with an improved efficiency in terms of material utilization, as compared with those designed to bend in an out-of-plane manner. Both component test and seismic performance test of the proposed damper have been conducted in this study. Hysteresis of the component test indicates consistent and effective energy-dissipative characteristics of the damper. The contour of cracks on the surface of the damper after testing is well correlated with the stress distribution obtained from numerical analysis. Moreover, excellent seismic performance of the proposed in-plane arched damper has been demonstrated via a series of shaking table tests on a five-story model structure. Experimental results indicate that, with the dampers implemented, the acceleration responses in both peak and root-mean-squares of all floors are significantly reduced and more pronounced with the earthquake intensity increased. Effectiveness of the seismic damper is also revealed from the increase of the effective modal damping of all modes identified.
44
Lou, Z., R. D. Ervin, and F. E. Filisko. "A Preliminary Parametric Study of Electrorheological Dampers." Journal of Fluids Engineering 116, no. 3 (September 1, 1994): 570–76. http://dx.doi.org/10.1115/1.2910315.
Повний текст джерелаАнотація:
In approaching the design of an electrorheology-based, semi-active suspension, the electrorheological component (ER damper) can be built as either a flow-mode, shear-mode, or mixed-mode type of damper. The source of damping force in the flow-mode is exclusively from flow-induced pressure drop across a valve, while that in the shear-mode is purely from the shear stress on a sliding surface. The dynamics of the fluid flow are included in the derivation of the zero-field damping forces. The control effectiveness is found to be strongly related to the dynamic constant (which is proportional to the square root of the vibration frequency) and, for shear-and flow-mode dampers, the ratio of the piston area to the cross-section of the ER control gap. To achieve the same performance, a flow-mode ER damper is not as compact and efficient as a shear-mode ER damper. With the same ER damping force, a mixed-mode damper is more compact than a shear-mode damper. However, the mixed-mode damper does not have as a low zero-field damping force as the shear-mode damper. The analysis is based on the assumption that the ER fluid is Bingham plastic.
45
Guo, Zenglin, Toshio Hirano, and R. Gordon Kirk. "Application of CFD Analysis for Rotating Machinery—Part I: Hydrodynamic, Hydrostatic Bearings and Squeeze Film Damper." Journal of Engineering for Gas Turbines and Power 127, no. 2 (April 1, 2005): 445–51. http://dx.doi.org/10.1115/1.1807415.
Повний текст джерелаАнотація:
The traditional method for bearing and damper analysis usually involves a development of rather complicated numerical calculation programs that may just focus on a simplified and specific physical model. The application of the general CFD codes may make this analysis available and effective where complex flow geometries are involved or when more detailed solutions are needed. In this study, CFX-TASCflow is employed to simulate various fixed geometry fluid-film bearing and damper designs. Some of the capabilities in CFX-TASCflow are applied to simulate the pressure field and calculate the static and dynamic characteristics of hydrodynamic, hydrostatic, and hybrid bearings as well as squeeze film dampers. The comparison between the CFD analysis and current computer programs used in industry has been made. The results show reasonable agreement in general. Some of the possible reasons for the differences are discussed. It leaves room for further investigation and improvement on the methods of computation.
46
Khazaei, Mohsen, Reza Vahdani, and Ali Kheyroddin. "Optimal Location of Multiple Tuned Mass Dampers in Regular and Irregular Tall Steel Buildings Plan." Shock and Vibration 2020 (September 16, 2020): 1–20. http://dx.doi.org/10.1155/2020/9072637.
Повний текст джерелаАнотація:
Tuned mass dampers are one of the most common devices for the passive control of structures subjected to earthquakes. The structure of these dampers consists of three main parameters: mass, damping, and stiffness. Tuned mass dampers reduce the amplitude of the responses affecting on a mode. In most cases, only a single TMD (tuned mass damper) or a few dampers at several points above the building height are installed on the roof of the building, requiring considerable mass and space in some parts of the structure as overhead. It is also more important to predict the elements that will meet the required mass. In this research, the performance of multiple tuned mass dampers (MTMDs) is investigated in L- and U-shaped regular and irregular tall steel buildings with 10 and 20 floors, under the near- and far-field records. Nonlinear time history analysis is also applied to evaluate the multiple tuned mass dampers effects on the seismic responses of the structures. The SAP2000 API and MATLAB genetic algorithm are used to determine the optimal location of the MTMDs in the roof plans of the buildings. The results show the effects of multiple tuned mass dampers in reducing the seismic response of acceleration, displacement, and base shear up to 50, 40, and 40% in average, respectively. The results of determining the optimum location of MTMDs in the models indicate the importance of the symmetry of the dampers relative to the centre of mass of the building.
47
Kong, Ling Jun, Xue Hua Dong, Yan Bei Chen, Xiang Liang Ning, Jing Tao Wang, and Jin Qiang Liu. "The Mechanical Properties of the Superplastic Zn-22Al Alloy at Different Processings." Advanced Materials Research 337 (September 2011): 354–57. http://dx.doi.org/10.4028/www.scientific.net/amr.337.354.
Повний текст джерелаАнотація:
To develop a superplastic damper, the mechanical properties of the superplastic Zn-22Al alloy differently processed are studied by the test, at room temperature. It is indicated that the alloy at the air cooling after rolling processing has better mechanical properties at room temperature, such as higher ductility and lower work-hardening, which is very useful to a seismic damper.
48
Jia, Sihui, and Mingzhang Luo. "Monitoring of Liquid Viscosity for Viscous Dampers through a Wireless Impedance Measurement System." Applied Sciences 12, no. 1 (December 24, 2021): 189. http://dx.doi.org/10.3390/app12010189.
Повний текст джерелаАнотація:
Viscous dampers are a type of seismic damping equipment widely used in high-rise buildings and bridges. However, the viscosity of the damping fluid inside the viscous damper will change over time during its use, which significantly reduces the seismic performance of the viscous damper. Hence, it is necessary to monitor the viscosity of the fluid inside the damper over its service life. In this paper, a damping fluid viscosity monitoring method based on wireless impedance measurement technology is proposed. A piezoelectric sensor is installed in a damper cylinder specimen, and the viscosity of the damping fluid is determined by measuring the piezoelectric impedance value of the sensor. In this study, 10 samples of damping fluids with different viscosities are tested. In order to quantitatively correlate damping fluid viscosity and electrical impedance, a viscosity index (VI) based on the root mean square deviation (RMSD) is proposed. The experimental results show that the variation of the real part in the impedance signal can qualitatively determine the damping fluid viscosity while the proposed VI can effectively and quantitatively identify the damping fluid viscosity.
49
Easwaran, V., and A. Craggs. "Transient response of lightly damped rooms: A finite element approach." Journal of the Acoustical Society of America 99, no. 1 (January 1996): 108–13. http://dx.doi.org/10.1121/1.414494.
Повний текст джерела
50
Zarzour, Mark, and John Vance. "Experimental Evaluation of a Metal Mesh Bearing Damper." Journal of Engineering for Gas Turbines and Power 122, no. 2 (January 3, 2000): 326–29. http://dx.doi.org/10.1115/1.483214.
Повний текст джерелаАнотація:
Metal mesh is a commercially available material used in many applications including seals, heat shields, filters, gaskets, aircraft engine mounts, and vibration absorbers. This material has been tested by the authors as a bearing damper in a rotordynamic test rig. The test facility was originally used to support the design of a turboprop engine, developing squirrel cages and squeeze film dampers for both the gas generator and power turbine rotors. To design the metal mesh damper, static stiffness and dynamic rap test measurements were first made on metal mesh samples in a specially designed nonrotating test fixture. These property tests were performed on samples of various densities and press fits. One sample was also tested in an Instron machine as an ancillary and redundant way to determine the stiffness. Using the stiffness test results and equations derived by a previous investigator, a spreadsheet program was written and used to size metal mesh donuts that have the radial stiffness value required to replace the squirrel cage in the power turbine. The squirrel cage and squeeze film bearing damper developed for the power turbine rotor was then replaced by a metal mesh donut sized by the computer code. Coast down tests were conducted through the first critical speed of the power turbine. The results of the metal mesh tests are compared with those obtained from previous testing with the squeeze film damper and show that the metal mesh damper has the same damping as the squeeze film at room temperature but does not lose its damping at elevated temperatures up to 103°C. Experiments were run under several different conditions, including balanced rotor, unbalanced rotor, heated metal mesh, and wet (with oil) metal mesh. The creep, or sag, of the metal mesh supporting the rotor weight was also measured over a period of several weeks and found to be very small. Based on these tests, metal mesh dampers appear to be a viable and attractive substitute for squeeze film dampers in gas turbine engines. The advantages shown by these tests include less variation of damping with temperature, ability to handle large rotor unbalance, and the ability (if required) to operate effectively in an oil free environment. Additional testing is required to determine the endurance properties, the effect of high impact or maneuver loads, and the ability to sustain blade loss loads (which squeeze films cannot handle). [S0742-4795(00)01002-4]