oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Air Plasma Mitigation of Shock Wave  [PDF]
Spencer P. Kuo
Advances in Aerospace Science and Technology (AAST) , 2016, DOI: 10.4236/aast.2016.12006
Abstract: Shock wave is a detriment in the development of supersonic aircrafts; it increases flow drag as well as surface heating from additional friction; it also initiates sonic boom on the ground which precludes supersonic jetliner to fly overland. A shock wave mitigation technique is demonstrated by experiments conducted in a Mach 2.5 wind tunnel. Non-thermal air plasma generated symmetrically in front of a wind tunnel model and upstream of the shock, by on-board 60 Hz periodic electric arc discharge, works as a plasma deflector, it deflects incoming flow to transform the shock from a well-defined attached shock into a highly curved shock structure. In a sequence with increasing discharge intensity, the transformed curve shock increases shock angle and moves upstream to become detached with increasing standoff distance from the model. It becomes diffusive and disappears near the peak of the discharge. The flow deflection increases the equivalent cone angle of the model, which in essence, reduces the equivalent Mach number of the incoming flow, manifesting the reduction of the shock wave drag on the cone. When this equivalent cone angle exceeds a critical angle, the shock becomes detached and fades away. This shock wave mitigation technique helps drag reduction as well as eliminates sonic boom.
Mechanism of laser-induced plasma shock wave evolution in air

Zhao Rui,Liang Zhong-Cheng,Han Bing,Zhang Hong-Chao,Xu Rong-Qing,Lu Jian,Ni Xiao-Wu,

中国物理 B , 2009,
Abstract: A theoretical model is proposed to describe the mechanism of laser-induced plasma shock wave evolution in air. To verify the validity of the theoretical model, an optical beam deflection technique is employed to track the plasma shock wave evolution process. The theoretical model and the experimental signals are found to be in good agreement with each other. It is shown that the laser-induced plasma shock wave undergoes formation, increase and decay processes; the increase and the decay processes of the laser-induced plasma shock wave result from the overlapping of the compression wave and the rarefaction wave, respectively. In addition, the laser-induced plasma shock wave speed and pressure distributions, both a function of distance, are presented.
Influence of air pressure on mechanical effect of laser plasma shock wave
Zhang Yu-Zhu,Wang Guang-An,Zhu Jin-Rong,Shen Zhong-Hu,Ni Xiao-Wu,Lu Jian,
章玉珠
,王广安,朱金荣,沈中华,倪晓武,陆 建

中国物理 B , 2007,
Abstract: The influence of air pressure on mechanical effect of laser plasma shock wave in a vacuum chamber produced by a Nd:YAG laser has been studied. The laser pulses with pulse width of 10ns and pulse energy of about 320mJ at 1.06$\mu $m wavelength is focused on the aluminium target mounted on a ballistic pendulum, and the air pressure in the chamber changes from $2.8\times 10^{3}$ to 1.01$\times $10$^{5 }$Pa. The experimental results show that the impulse coupling coefficient changes as the air pressure and the distance of the target from focus change. The mechanical effects of the plasma shock wave on the target are analysed at different distances from focus and the air pressure.
Shock (Blast) Mitigation by "Soft" Condensed Matter  [PDF]
Vitali F. Nesterenko
Physics , 2003,
Abstract: It is a common point that "soft" condensed matter (like granular materials or foams) can reduce damage caused by impact or explosion. It is attributed to their ability to absorb significant energy. This is certainly the case for a quasistatic type of deformation at low velocity of impact where such materials are widely used for packing of fragile devices. At the same time a mitigation of blast phenomena must take into account shock wave properties of "soft" matter which very often exhibit highly nonlinear, highly heterogeneous and dissipative behavior. This paper considers applications of "soft" condensed matter for blast mitigation using simplified approach, presents analysis of some anomalous effects and suggestions for future research in this exciting area.
Role of on-board discharge in shock wave drag reduction and plasma cloaking
Qiu Xiao-Ming,Tang De-Li,Sun Ai-Ping,Liu Wan-Dong,Zeng Xue-Jun,
邱孝明
,唐德礼,孙爱萍,刘万东,曾学军

中国物理 B , 2007,
Abstract: In the present paper, a physical model is proposed for reducing the problem of the drag reduction of an attached bow shock around the nose of a high-speed vehicle with on-board discharge, to the problem of a balance between the magnetic pressure and gas pressure of plane shock of a partially ionized gas consisting of the environmental gas around the nose of the vehicle and the on-board discharge-produced plasma. The relation between the shock strength and the discharge-induced magnetic pressure is studied by means of a set of one-fluid, hydromagnetic equations reformed for the present purpose, where the discharge-induced magnetic field consists of the electron current (produced by the discharge)-induced magnetic field and the partially ionized gas flow-induced one. A formula for the relation between the above parameters is derived. It shows that the discharge-induced magnetic pressure can minimize the shock strength, successfully explaining the two recent experimental observations on attached bow shock mitigation and elimination in a supersonic flow during on-board discharge Phys. Plasmas 9 (2002) 721 and Phys. Plasmas 7 (2000) 1345]. In addition, the formula implies that the shock elimination leaves room for a layer of higher-density plasma rampart moving around the nose of the vehicle, being favourable to the plasma radar cloaking of the vehicle. The reason for it is expounded.
Gravimagnetic shock waves in the anisotropic plasma  [PDF]
Yu. G. Ignatyev,D. N. Gorokhov
Physics , 2011,
Abstract: The relativistic magnetohydrodynamic equations for the anisotropic magnetoactive plasma are obtained and accurately integrated in the plane gravitational wave metrics. The dependence of the induction mechanism of the gravimagnetic shock waves on the degree of the magnetoactive plasma anisotropy is analyzed.
Air plasma for medical applications  [PDF]
Spencer P. Kuo
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.59061
Abstract: The design and the electric and emission characteristics of two handheld air plasma spray generators are presented. The plasma is generated by 60 Hz periodic discharges between two concentrically cylindrical electrodes. A ring magnet is used to rotate arc discharges, which sprays outward by an air flow. The rotation of arc discharges keeps the generated plasma in non-equilibrium state and at relatively low temperature (<55°C). The plasma effluent yet contains high energy electrons which dissociate molecular oxygen into atomic oxygen. The emission spectroscopy of the plasma plume reveals that the plasma effluent, which carries abundant atomic oxygen, extends from the cap of the plasma spray by about 25 to 30 mm. Tests on blood droplets and smeared blood samples revealed the effectiveness and mechanism of low temperature air plasma on clotting blood. Tests on oral pathogens show that air plasma creates a zone of microbial growth inhibition in each of six treated samples, including those of grampositive bacteria and fungi, and on a cultivating biofilm sample of Streptococcus mutans UA159. The medical applications of the air plasma sprays for 1) bleeding control, 2) wound healing, and 3) dental disinfection, are then illustrated and discussed. As animal models, pigs were used in the tests of stopping wound bleeding and post-operative observation of wound healing by this air plasma spray. The results show that the bleeding from a cut to an ear artery is stopped swiftly; this air plasma spray also shortens wound healing time to about half (from 14 days to 8 days) after stopping the bleeding of a cross cut wound in the ham area. In-vitro tests demonstrate that the plasma effluent of the spray can prevent the formation of dental biofilms and further eliminate the mature biofilms.
Development of Air Treatment Technology Using Plasma Method  [cached]
Rasoul Yarahmadi,Sayed Bager Mortazavi,Parvin Moridi
International Journal of Occupational Hygiene , 2012,
Abstract: Due to the physicochemical properties of nitrogen oxides as active molecules, the removal of this group of pollutants has always been considered as a matter of concern for specialists. The present study seeks to develop the removal technique of nitrogen oxides "as a major type of air pollutant" by means of non-thermal plasma process under atmospheric conditions. Besides having the potential to reduce energy consumption in the pollutant removal process, non-thermal plasma technology also provides particular flexibility for the simultaneous removal and mitigation of the secondary pollutants. In this research we have used the Dielectric Barrier Discharge (DBD) plasma process to achieve an effective conversion of Nitrogen Oxides (NOx). As a result of the collisions between the electrons and the airflow containing NOx, active radicals and molecules are generated in a limited and controlled volume (plasma reactor) and the conversion and removal process is then carried out in the presence of hydrocarbon as reducer gas. The key factors for NOx conversion especially in the non-thermal plasma condition are the geometric structure and design of the reactor, type of discharge, type of power supply, temperature, space velocity, propane/NOx mole ratio, and voltage. In the present study, the factors of temperature, mole ratio of the reducer and input voltage were examined. The results showed that the optimal conditions for conversion of NOx into N2 and O2 are temperature of 180°C, propane/NOx mole ratio of 0.5, and voltage of 5 KV. Under the optimal conditions acquired, NOx conversion was 0.79 in the 100 PPM concentration. Under the conditions of the present study, 1-5 PPM Ozone, Formaldehyde, and CO was generated as the undesirable pollutants.
Climate Change and Air Pollution: Exploring the Synergies and Potential for Mitigation in Industrializing Countries  [PDF]
Frances C. Moore
Sustainability , 2009, DOI: 10.3390/su1010043
Abstract: Air pollutants such as tropospheric ozone and black carbon (soot) also contribute to the greenhouse effect. Black carbon is thought to be the second or third most important anthropogenic contributor to global warming, while troposheric ozone is the fourth most important. Both are also major components of indoor and outdoor air pollution. This paper reviews the existing literature of the health, economic, and climatic impacts of tropospheric ozone and black carbon emissions, together with mitigation options. The local nature of many of the impacts, combined with their short atmospheric lifetime and the existence of cost-effective abatement technologies that are already widely deployed in developed countries means reducing these emissions provides a highly climatically-effective mitigation option that is also appropriate to the development strategy of industrializing countries.
A Method to Assess the Potential Effects of Air Pollution Mitigation on Healthcare Costs  [PDF]
Bj rn S tterstr m,Marie Kruse,Henrik Br nnum-Hansen,Jakob Hjort B nl kke,Esben Meulengracht Flachs,Jan S rensen
Journal of Environmental and Public Health , 2012, DOI: 10.1155/2012/935825
Abstract: Objective. The aim of this study was to develop a method to assess the potential effects of air pollution mitigation on healthcare costs and to apply this method to assess the potential savings related to a reduction in fine particle matter in Denmark. Methods. The effects of air pollution on health were used to identify “exposed” individuals (i.e., cases). Coronary heart disease, stroke, chronic obstructive pulmonary disease, and lung cancer were considered to be associated with air pollution. We used propensity score matching, two-part estimation, and Lin’s method to estimate healthcare costs. Subsequently, we multiplied the number of saved cases due to mitigation with the healthcare costs to arrive to an expression for healthcare cost savings. Results. The potential cost saving in the healthcare system arising from a modelled reduction in air pollution was estimated at €0.1–2.6 million per 100,000 inhabitants for the four diseases. Conclusion. We have illustrated an application of a method to assess the potential changes in healthcare costs due to a reduction in air pollution. The method relies on a large volume of administrative data and combines a number of established methods for epidemiological analysis.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.