• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.139-148
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• 2016

The passive control methods such as horizontal and vertical fences on the lower surface of the bluff body were applied to suppress the vortex shedding and enhance the aerodynamic stability of flow. For investigating the effects of the passive control methods, wind tunnel experiments on the unsteady flow field around a bluff body near a moving ground were performed. The boundary layer and velocity profiles were measured by the Hot Wire Anemometer (HWA) system and the vortex shedding patterns and flow structures in a wake region were visualized via the Particle Image Velocimetry (PIV) system. Also, it is a measuring on moving ground condition that the experimental values of the critical gap distances, Strouhal numbers and aerodynamic force FFT analyses. Through the experiments, we found that the momentum supply due to moving ground caused the vortex shedding at the lower critical gap distance rather than that of fixed ground. The horizontal and vertical fences increase the critical gap distance and it can suppress the vortex shedding. Consequently, the stability characteristics of the bluff body near a moving ground could be effectively enhanced by the simple passive control such as the vertical fences.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1036-1045
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• 2016

This paper presents a novel control strategy for passive output filter reduction using an active output filter. The proposed method achieves the dual-function of regulating the output voltage ripple and output voltage variation during load transients. The novel control strategy allows traditional simple voltage controllers to be used, without requiring the expensive current sensors and complex controllers used in conventional approaches. The proposed method is verified with results from a 125-W forward converter.

• Smart Structures and Systems
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• v.20 no.5
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• pp.637-640
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• 2017

The adoption of cladding panels as dissipation device is a sort of passive control "ante litteram" for residential and commercial buildings. This paper gives details on the current technology outlining the difference between buffer panels and cladding panels. The discussion of robustness and resilience of the resulting system is afforded. It is shown that the strength of such solution, originally related to economy and light weight, is mainly associated with the respect of the main robustness requisites, as well as the short time it requires for removal and replacement (resilience).

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3635-3639
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• 2013

Background: Conclusive evidence exists about associations between several life-threatening diseases and passive smoking. The objective of our study was to investigate the prevalence of passive smoking among Iranian dental students, to assess their attitudes towards tobacco control programs, and to explore the association between these two and tobacco use. Methods: In eight randomly selected dental schools, all fourth-year students were surveyed by means of a self-administered anonymous questionnaire in December 2010. The Global Health Professions Student Survey (GHPSS) questionnaire served as the data collection instrument. Exposure to environmental tobacco smoke (ETS) was assessed during the previous week. Chi-square test, logistic regression, and linear regression served for statistical analyses. Results: The response rate was 84% (325 students, 66% female). Exposure to ETS was reported by 74% of the participants. Men were significantly more exposed to ETS at home, and in other places than were women. Most of the students agreed on queried tobacco control policies. The lowest agreement (72%) was for banning smoking in coffee shops and teahouses. A logistic regression model showed that adjusted for gender, passive smoking at home is significantly associated with current tobacco use. A linear regression model suggested that the total score of attitudes is significantly associated with passive smoking at home, passive smoking in other places, tobacco use experience, and current tobacco use. Conclusions: The study reports high exposure to ETS among dental students, and its association with current tobacco use and attitudes towards tobacco control.

• Structural Engineering and Mechanics
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• v.9 no.4
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• pp.383-396
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• 2000

A new structure-vibration-control approach is proposed which uses a passive coupling element between two parallel structures to reduce the seismic response of a system due to earthquake excitation. Dynamic characteristics of the two coupled single-degree-freedom systems subject to stationary white-noise excitation are examined by means of statistical energy analysis (SEA) techniques. Optimal parameters of the passive coupling element such as damping and stiffness under different circumstances are determined with an emphasis on the influence of the structural parameters of the system on the optimal parameters and control effectiveness. Numerical results including the root mean square values of the response due to the filtered white-noise excitation and the time-histories of response to El Centro 1940 NS excitation are presented.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.505-512
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• 2005

MR damper is one of the most promising control devices for civil engineering applications to earthquake hazard mitigation. However, a control system including a power supply, controller, and sensors is required to maximize the performance of the MR damper and this complicated control system is not effective to most of large civil structures. This paper proposes and experimentally verified a smart passive damping system using MR(Magnetorheological) dampers by introducing electromagnetic induction(EMI) system as an external power source to MR damper. It is easy to build up and maintain EMI system, because it does not require any control system such as a power supply, controller, and sensors. Numerical simulations using experimental model of EMI system are carried to verify the effectiveness of the proposed EMI system. The performances of smart passive damping system are compared with those of passive and semiactive MR dampers.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.97-103
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• 2011

With the aim to increase blade loadings and stable operating range in highly loaded compressors, this article has been conducted to explore, through a numerical parametric study, the potential of passive control using slotted bladings in cascade configurations. The objective of this numerical investigation is to analyze the influence of location, width and slope of the slots and therefore identify the optimal configuration. The approach is based on two dimensional cascade geometry, low speed regime, steady state and turbulent RANS model. The results show the efficiency of this passive technique to delay separation and enhance aerodynamic performances of the compressor cascade. A maximum of 28.3% reduction in loss coefficient have been reached, the flow turning is increased with approximately $5^0$ and high loading over a wide range of angle of attack have been obtained for the optimized control parameter.

• Earthquakes and Structures
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• v.4 no.6
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• pp.649-670
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• 2013

It is known that a base-isolated building exhibits a large response to a long-duration, long-period wave and an inter-connected system without base-isolation shows a large response to a pulse-type wave. To compensate for each deficiency, a new hybrid passive control system is investigated in which a base-isolated building is connected to another building (free wall) with oil dampers. It is demonstrated that the present hybrid passive control system is effective both for pulse-type ground motions and long-duration and long-period ground motions and has high redundancy and robustness for a broad range of disturbances.

• International Journal of Control, Automation, and Systems
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• v.5 no.2
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• pp.200-207
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• 2007

The passive direction finding cross localization method is widely adopted in passive tracking, therefore there will exist masses of false intersection points. Eliminating these false intersection points correctly and quickly is a key technique in passive localization. A new method is proposed for passive locating and tracking multi-jammer target in this paper. It not only solves the difficulty of determining the number of targets when masses of false intersection points existing, but also solves the initialization problem of elastic network. Thus this method solves the problem of multi-jammer target correlation and the elimination of static false intersection points. The method which dynamically establishes multiple hypothesis trajectory trees solves the problem of eliminating the remaining false intersection points. Simulation results show that computational burden of the method is lower, the elastic network can more quickly find all or most of the targets and have a more probability of locking the real targets. This method can eliminate more false intersection points.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1831-1839
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• 2003

This paper deals with design and control of passive multiple trailer systems fer practical applications. Due to cost and complexity of trailer mechanism, passive systems are preferred to active systems in this research. The control objective is to minimize trajectory tracking errors of passive multiple trailers. Three types of passive trailer systems-direct-hooked, three-point, and off-hooked- are discussed in this paper. Trajectory tracking performance and stability issues under constant velocity motion are carried out for three types. Various simulations and experiments have been also performed for these three types. It is shown that the proposed off-hooked trailer system produces better tracking performance than the other types.