WorldWideScience

Sample records for aerostatics

  1. Spectral properties and identification of aerostatic bearings

    Institute of Scientific and Technical Information of China (English)

    Jan Kozánek; Ladislav P(u)st

    2011-01-01

    Modified rotor kit BentlyNevada was used for dynamic characteristics measurements of new developed aerostatic bearings. Mathematical model of these bearings is considered as linear. Model was identified with the help of harmonic force excitation independently from the speed of journal rotation. The stiffness and damping matrices were identified for different air inlet pressures. The calculated spectral properties allow to determine the stability boundary for suitable variation of model parameters.

  2. Advanced aerostatic analysis of long-span suspension bridges

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    As the span length of suspension bridges increases, the diameter of cables and thus the wind load acting on them, the nonlinear wind-structure interaction and the wind speed spatial non-uniformity all increase consequently, which may have unnegligible influence on the aerostatic behavior of long-span suspension bridges. In this work, a method of advanced aerostatic analysis is presented firstly by considering the geometric nonlinearity, the nonlinear wind-structures and wind speed spatial non-uniformity. By taking the Runyang Bridge over the Yangtze River as example, effects of the nonlinear wind-structure interaction, wind speed spatial non-uniformity, and the cable's wind load on the aerostatic behavior of the bridge are investigated analytically. The results showed that these factors all have important influence on the aerostatic behavior, and should be considered in the aerostatic analysis of long and particularly super long-span suspension bridges.

  3. Hydrostatic, aerostatic and hybrid bearing design

    CERN Document Server

    Rowe, W Brian

    2012-01-01

    Solve your bearing design problems with step-by-step procedures and hard-won performance data from a leading expert and consultant Compiled for ease of use in practical design scenarios, Hydrostatic, Aerostatic and Hybrid Bearing Design provides the basic principles, design procedures and data you need to create the right bearing solution for your requirements. In this valuable reference and design companion, author and expert W. Brian Rowe shares the hard-won lessons and figures from a lifetime's research and consultancy experience. Coverage includes: Clear e

  4. Swot analysis of using aerostats for surveillance in counter terrorism

    Science.gov (United States)

    ćetin, Hüseyin

    2013-06-01

    In today's conjuncture, the terrorist activities are the most compelling issue for the defence forces in maintaining homeland security. Especially, the terrorist elements that penetrate the homeland may give harm. This harm can be minimized by preventing the terrorist penetrations from homeland borders. In counter terrorism, having Intelligence, Surveillance and Reconnaissance (ISR) capability and using this capability by twenty four hours is deterrence for the terrorist groups. Aerostats emerge as the ideal platform which can provide this capability. Aerostats are unmanned and aerodynamically shaped balloons that are stayed in the air, fixed to the ground by steel cable(s). The aerostat is made of a large fabric envelope that is filled with nonflammable helium gas, which provides the lifting force. The cables also serve to supply the electrical power to the aerostat systems, and for data relay between the aerostat and the ground station. Aerostats are different from the other manned and Unmanned Aerial Vehicles (UAVs) because of aerostats' capabilities such as cost effectiveness, long endurance and high resolution image transmission. Especially having uninterrupted image transmission and surveillance capabilities is important to be advantageous in counter terrorism. In this article, a short definition of terrorism has been given and then the importance of ensuring the homeland border security has been emphasized in counter terrorism. In addition, the questions of "what are the technical capabilities, the usage areas and the purposes of aerostats?" will be introduced as a result of literature review. Finally the strengths and weaknesses of aerostats, opportunities and threats for the near future will be introduced by using "SWOT" analysis method.

  5. Nonlinear vibrations and stability of aerostatic bearing

    Directory of Open Access Journals (Sweden)

    Kozánek J.

    2008-12-01

    Full Text Available Bearings based on aerostatic principle belong to the new machine elements advantageous for low- and high-speed applications, but their dynamic and stability properties are not yet sufficiently known. This paper presents a new elaborated method and gained results of theoretical investigation of dynamic properties of aerostatic bearing in general dimensionless form. It is aimed also as a supporting tool for diagnostic and identification methods used at developing of new bearings proposed by TECHLAB, Prague for industrial applications. Mathematical model expresses nonlinear and evolutive properties in the entire area of bearing clearance, contains sufficient number of free parameters in functions of restoring and damping forces and can therefore describe all types of motions occurring in gas bearings as periodic, quasi-periodic, including beats and instability, which can leads to chaotic and self-excited vibrations. The influence of non-diagonal elements of stiffness and damping matrices of linearized model on the spectral properties and the stability of system is investigated, too.

  6. Design, Testing, and Realisation of a Medium Size Aerostat Envelope

    Directory of Open Access Journals (Sweden)

    A. Kumar

    2016-03-01

    Full Text Available The design, testing and realisation aspects during the development of a medium size aerostat envelope in the present work. The payload capacity of this aerostat is 300 kg at 1 km above mean sea level. The aerostat envelope is the aerodynamically shaped fabric enclosure part of the aerostat which generally uses helium for lifting useful payloads to a specified height. The envelope volume estimation technique is discussed which provides the basis for sizing. The design, material selection, testing and realisation aspects of this aerostat envelope are also discussed. The empirical formulas and finite element analysis are used to estimate the aerodynamic, structural and other design related parameters of the aerostat. Equilibrium studies are then explained for balancing forces and moments in static conditions. The tether profile estimation technique is discussed to estimate blow by distance and tether length. A comparison of estimated and measured performance parameters during trials has also been discussed.Defence Science Journal, Vol. 66, No. 2, March 2016, pp.93-99, DOI: http://dx.doi.org/10.14429/dsj.66.9291

  7. An aerostat-supported ELF/VLF transmitter

    Science.gov (United States)

    Field, E. C., Jr.; Kies, L. R.; Bannister, P. R.; Ingram, R. F.; Hopkins, W. D.; Roberts, M. A.

    1989-03-01

    A demonstration of an aerostat-supported extremely low frequency/very low frequency (ELF/VLF) transmitting antenna was performed. At ELF the vertical electric dipole (VED) antenna radiated at least 100,000 times more power than would a horizontal electric dipole having the same moment. That efficiency was achieved with an altitude of 12,500 feet (3810 m). Calculations show that the radiated power will increase as the fourth power of aerostat altitude. The tether antenna exhibited a corona onset voltage of 180 kV and was resistant to the degrading effects of ELF corona. Prolonged in-corona operation is therefore possible. The antenna was continuously tuned, despite changes in height and capacitance caused by the aerostat flight dynamics. The huge 300-H ELF tuning inductor posed no problem. Enhanced VED moments were achieved at ELF by operation at voltages up to 260 kV, 40% above the corona onset voltage. At VLF the antenna emulated a monopole that had a radiation efficiency greater than 90%. The measured bandwidths were large: 1.5 kHz at 23 kHz and 3.5 kHz at 34 kHz. The antenna height exceeded one-quarter wavelength at VLF, so the antenna could be tuned capacitively and required relatively low base voltages. At both VLF and ELF the measured fields agreed closely with predictions.

  8. Aerostatic Stability of Long-Span Cable-Stayed Bridges: Parametric Study

    Institute of Scientific and Technical Information of China (English)

    程进; 江见鲸; 肖汝诚; 项海帆

    2003-01-01

    The increasing span of cable-stayed bridges has focused more attention on the aerostatic stability of the design and construction of such bridges. This paper presents a new method to analyze the nonlinear aerostatic stability of cable-stayed bridges including all three components of the wind load and the geometric nonlinearity. The analysis was used to investigate the effects of the wind angle of incidence, the wind load of individual bridge elements, the sagging of cable elements, the changes of tower height and the changes of side span length on the aerostatic stability of cable-stayed bridges. The results show that the wind angle of incidence and the wind loads on the cables have an important effect on the aerostatic stability of cable-stayed bridges.

  9. Detection of impulsive sources from an aerostat-based acoustic array data collection system

    Science.gov (United States)

    Prather, Wayne E.; Clark, Robert C.; Strickland, Joshua; Frazier, Wm. Garth; Singleton, Jere

    2009-05-01

    An aerostat based acoustic array data collection system was deployed at the NATO TG-53 "Acoustic Detection of Weapon Firing" Joint Field Experiment conducted in Bourges, France during the final two weeks of June 2008. A variety of impulsive sources including mortar, artillery, gunfire, RPG, and explosive devices were fired during the test. Results from the aerostat acoustic array will be presented against the entire range of sources.

  10. Frictional Characteristics of a Small Aerostatic Linear Bearing

    Directory of Open Access Journals (Sweden)

    Ryosuke Araki

    2015-04-01

    Full Text Available Frictional characteristics of a small aerostatic linear bearing are accurately evaluated by means of a method, in which the force acting on the moving part of the bearing is measured as the inertial force. An optical interferometer is newly developed to measure the Doppler shift frequency of the laser light reflected on the small moving part. From the measured time-varying Doppler shift frequency, the velocity, the position, the acceleration and the inertial force of the moving part are numerically calculated. It is confirmed that the dynamic frictional force acting inside the bearing is almost proportional to the velocity of the moving part and is similar to the theoretical value calculated under the assumption that the flow inside the bearing is the Couette flow.

  11. AEROSTATIC AND AERODYNAMIC MODULES OF A HYBRID BUOYANT AIRCRAFT: AN ANALYTICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Anwar Ul Haque

    2015-05-01

    Full Text Available An analytical approach is essential for the estimation of the requirements of aerodynamic and aerostatic lift for a hybrid buoyant aircraft. Such aircrafts have two different modules to balance the weight of aircraft; aerostatic module and aerodynamic module. Both these modules are to be treated separately for estimation of the mass budget of propulsion systems and required power. In the present work, existing relationships of aircraft and airship are reviewed for its further application for these modules. Limitations of such relationships are also disussed and it is precieved that it will provide a strating point for better understanding of design anatomy of such aircraft.

  12. Aerostat-Based Sampling of Emissions from Open Burning and Open Detonation of Military Ordnance

    Science.gov (United States)

    Emissions from open detonation (OD), open burning (OB), and static firing (SF) of obsolete military munitions were collected using an aerostat-lofted sampling instrument maneuvered into the plumes with remotely controlled tether winches. PM2.5, PM10, metals, volatile organic comp...

  13. Simulation of the fluid structure interaction for an aerostatic bearing and a flexible substrate

    NARCIS (Netherlands)

    Olieslagers, R.; Wild, M. de; Melick, S. van; Knaapen, R.

    2014-01-01

    The fluid structure interaction for an aerostatic bearing and a substrate is solved numerically by a semi-analytical model, programmed in the software package MATLAB. This semi-analytical model uses a fluidic network of resistances and capacities to solve the pressure field in the bearing channel. T

  14. Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

    Institute of Scientific and Technical Information of China (English)

    Zhiwen LIU; Zhengqing CHEN; Gao LIU; Xinpeng SHAO

    2009-01-01

    The aerodynamic interference effects on aero-static coefficients of twin deck bridges with large span were investigated in detail by means of wind tunnel test.The distances between the twin decks and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin decks. The research results have shown that the drag coefficients of the leeward deck are much smaller than that of a single leeward deck. The drag coefficients of a windward deck decrease slightly com-pared with that of a single deck. The lift and torque coefficients of windward and leeward decks are also affected slightly by the aerodynamic interference of twin decks. And the aerodynamic interference effects on lift and torque coefficients of twin decks can be neglected.

  15. Coupled-mode induced transparency in aerostatically-tuned microbubble whispering gallery resonators

    CERN Document Server

    Yang, Yong; Ward, Jonathan; Chormaic, Síle Nic

    2015-01-01

    Coupled-mode induced transparency is realized in a single microbubble whispering gallery mode resonator. Using aerostatic tuning, we find that the pressure induced shifting rates are different for different radial order modes. A finite element simulation considering both the strain and stress effects shows a GHz/bar difference and this is confirmed by experiments. A transparency spectrum is obtained when a first order mode shifts across a higher order mode through precise pressure tuning. The resulting lineshapes are fitted with the theory. This work lays a foundation for future applications in microbubble sensing.

  16. An ultrahigh sensitivity, high resolution, aerostatic pressure sensor using microbubble resonators

    CERN Document Server

    Yang, Yong; Ward, Jonathan M; Chormaic, Síle Nic

    2016-01-01

    Sensors based on whispering gallery resonators can push achievable sensitivities and resolutions to their limits, while maintaining minute footprints. Here, we report on the fabrication of a microbubble resonator using two CO$_2$ beams focused on a microcapillary; the resulting microbubble has an ultrathin wall. We show that, even when the wall is as thin as 500 nm, an intrinsic quality factor of $10^7$ is achievable at the telecommunications C-band. Considering strain and stress of the material, we investigate the feasibility of using the microbubble as an aerostatic pressure sensor. The measured sensitivity is 19 GHz/bar and is at the limit of current techniques. We have found that the sensitivity can be improved to 38 GHz/bar at the 780 nm wavelength range, where the resolution for pressure sensing is 0.14 mbar and the Q-factor remains higher than $10^7$.

  17. Acoustic detection and localization of weapons fire by unattended ground sensors and aerostat-borne sensors

    Science.gov (United States)

    Naz, P.; Marty, Ch.; Hengy, S.; Miller, L. S.

    2009-05-01

    The detection and localization of artillery guns on the battlefield is envisaged by means of acoustic and seismic waves. The main objective of this work is to examine the different frequency ranges usable for the detection of small arms, mortars, and artillery guns on the same hardware platform. The main stages of this study have consisted of: data acquisition of the acoustic signals of the different weapons used, signal processing and evaluation of the localization performance for various types of individual arrays, and modeling of the wave propagation in the atmosphere. The study of the propagation effects on the signatures of these weapons is done by comparing the acoustic signals measured during various days, at ground level and at the altitude of our aerostat (typically 200 m). Numerical modeling has also been performed to reinforce the interpretation of the experimental results.

  18. Vehicle tethered aerostat optoelectronic monitoring platform system for Shanghai World EXPO

    Science.gov (United States)

    Zhou, Weihu; Wang, Yawei; Han, Xiaoquan; Yuan, Jiang

    2010-08-01

    To monitor the whole Shanghai Expo Park, a vehicle tethered aerostat optoelectronic monitoring platform with the characteristic of time-sensitive and all-weather monitoring is described in detail in this paper, which is hung beneath the tethered balloon and equipped with a variety of payloads, including visible light monitoring system, infrared monitoring system, hyperspectral monitoring system, GPS/INS system, monitoring and control system and so on. These equipments can be used for real-time monitoring, environmental monitoring, and ground target location of Shanghai Expo Park. The output High Definition (HD) image of Shanghai Expo Park from visible light monitoring system is clear and stable, and the stabilization accuracy of visual axis is 0.07°(3δ). The optoelectronic monitoring platform system uses the target location technology based on Global Position System/Inertial Navigation System (GPS/INS) system to output real-time location data compatible with Geographic Information System (GIS). Test results show that the maximum errors between the location results (latitude and longitude) solved by the target location program and the reference target are 0.2 0/00(latitude) and 2 0/00(longitude). Now the whole system has been used for surveillance the Shanghai Expo Park since April 2010.

  19. Analysis of micro vibration in gas film of aerostatic guide way based on molecule collision theory

    Directory of Open Access Journals (Sweden)

    Yang Shao Hua

    2016-01-01

    Full Text Available Micro vibration of the aerostatic guide way has a significant impact on its dynamic characteristics and stability, which limits the development of pneumatic component. High pressure gas molecules have been collided with the supporting surface and the internal surface of the throttle during the flow process. Variable impulse of the surfaces aside for the gas film are affected by the changes of impulse which formed irregular impact force in horizontal and vertical direction. Micro-vibration takes place based on the natural frequency of the system and its frequency doubling. In this paper, the vibration model was established to describe the dynamic characteristics of the gas film, and the formation mechanism of micro vibration in the film is defined. Through the simulation analysis and experimental comparison, formation mechanism of the micro vibration in the gas film is confirmed. It was proposed that the micro vibration of gas film can be produced no matter whether there is a gas chamber or not in the throttle. Under the same conditions, the micro vibration of the guide way with air chamber is greater than that without any chamber. The frequency points of the vibration peaks are almost the same, as well as the vibration pattern in the frequency domain.

  20. Design and implementation of an active rectangular aerostatic thrust bearing stage with electromagnetic actuators

    Institute of Scientific and Technical Information of China (English)

    MAO JunHong; LI LiChuan

    2009-01-01

    The design and implementation of an active rectangular aerostaUc thrust bearing stage with electro-magnetic actuators are presented. The stage is fundamentally precise and simple since the out-of-plane degree-of-freedoms (DOF) of a thrust air bearing are closed-loop controlled by electromagnetic actua-tors. The design is one-moving-part with mechanical symmetry, and a commercially available air bear-ing is rigidly attached to the table. The actuators are four independent coils mounted to the guiding surface of the table with iron cores, which are directly machined on the table. A bench level prototype system is developed and out-of-plane axes decoupled models of the system are derived. A control al-gorithm synthesized by arbitrarily placing closed-loop poles according to the model with air bearing dynamics neglected is implemented by C programming language running on the DOS platform. The stage is capable of vertical direction precision micro-positioning and guiding 3-DOF plane motions without limiting the working range of plane motions. Positioning accuracy of the stage no longer de-pends upon design and manufacturing of an air bearing, while passive preload of the stage for a flat film aerostatic thrust bearing is eliminated.

  1. Coriolis Mass-Flowmeter for aerostatic gas amount determination in zero pressure stratosperic balloons.

    Science.gov (United States)

    Behar, Jean-Baptiste

    2016-07-01

    The CNES ballooning community regularly operates zero pressure balloons in many countries around the world (recently in France, Sweden, Canada and soon, Australia in 2017). An important operational flight parameter is the aerostatic gas mass injected into the balloon (currently helium and hydrogen in the study). Besides the lifting force, it determines mainly the ascent rate from which the adiabatic expansion depends directly. A too high ascent velocity in very cold air temperature profiles could result in a gas temperature drop which if too great, might induce brittleness of the envelope. A precise gas mass determination is therefore critical for performance as well as for mission safety. The various gas supply tanks in various countries all have different characteristics with possible uncertainties with regard to their volumes. This makes the currently used gas mass determination method based on supply tank pressure measurements unreliable. This method also relies on tank temperature, another source of inaccuracy in the gas amount determination. CNES has therefore prospected for alternative methods to reduce inaccuracies and perhaps also ease the operational procedures during balloon inflation. Coriolis mass-flowmeters which have reached industrial maturity, offer the great advantage over other flowmeters to be able to directly measure the mass of the transferred fluid, and not deducing it from other parameters as other types of flowmeters would do. An industrial contractor has been therefore assigned to integrate this solution into the CNES operational setup. This new system is to be tested in February 2016. The presentation will briefly explain the Coriolis flowmeter's principle and display the February 2016 performance tests' results. The expected incidence on zero pressure balloons' trajectories will also be discussed based on simulations ran on a balloon flight simulator software.

  2. Acoustic data analysis and scenario over watch from an aerostat at the NATO SET-153 field experiment

    Science.gov (United States)

    Reiff, Christian; Scanlon, Michael

    2012-06-01

    The purpose of the NATO SET-153 field experiment was to provide an opportunity to demonstrate multiple sensor technologies in an urban environment and determine integration capabilities for future development. The Army Research Laboratory (ARL) experimental aerostat was used primarily as a persistent over watch capability as a substitute for a UAV. Continuous video was recorded on the aerostat and segments of video were captured of the scenarios on the ground that the camera was following manually. Some of the segments showing scenario activities will be presented. The captured pictures and video frames have telemetry in the headers that provides the UTM time and the Inertial Navigation System (INS) GPS location and the inertial roll, pitch, and yaw as well as the camera gimbal pan and tilt angles. The timing is useful to synchronize the images with the scenario events providing activity ground truth. The INS, GPS, and camera gimbal angle values can be used with the acoustic solution for the location of a sound source to determine the relative accuracy of the solution if the camera is pointed at the sound source. This method will be confirmed by the use of a propane cannon whose GPS location is logged. During the field experiment, other interesting acoustic events such as vehicle convoys, platoon level firefights with vehicles using blanks, and a UAV helicopter were recorded and will be presented in a quick analysis.

  3. 三塔悬索桥施工过程静风稳定性分析%Aerostatic Stability Analysis of Three-tower Suspension Bridge During Construction

    Institute of Scientific and Technical Information of China (English)

    郭辉; 孙华卿

    2011-01-01

    By taking a three-tower suspension bridge--Taizhou Highway Bridge over Yangtze River with main span of 1 080 m as example, by using 3D structural nonlinear aerostatic analysis, the influence of deck erection sequence on the aerostatic stability during the whole construction process is revealed, and the favorable deck erection sequence is also proposed with respect to the aerostatic stability.The resuhs show that good aerostatic stability can be obtained for threetower suspension bridges as the deck erection starts simultaneously from the pylons to the midpoints of main spans.%以在建主跨为1080m的三塔双跨悬索桥——泰州长江公路大桥为工程背景,采用三维非线性空气静力稳定性分析方法,分析不同的主梁架设顺序对三塔悬索桥施工阶段空气静力稳定性的影响,确定具有良好抗风稳定件的施工方案。结果表明:三塔悬索桥主梁拼装采用从桥塔处至跨中施工时,可以获得较好的空气静力稳定性。

  4. 多孔质节流空气静压轴承静态性能实验研究%Experimental Research and Analysis of Aerostatic Bearing

    Institute of Scientific and Technical Information of China (English)

    田富竟; 尹自强; 王建敏; 彭永华

    2011-01-01

    本文采用不锈钢多孔质材料研制了一种新的空气静压轴承,并对不同平均孔径的多孔质空气静压轴承以及一种表面复合节流空气静压轴承的承载能力和刚度进行了实验测试和分析,结果表明,选用合适的不锈钢多孔质材料以及适当的加工方法可以制造高承载能力与高刚度的空气静压轴承.%A new aerostatic bearing is developed by applying the stainless steel porous material. The experimental testing and analysis are carried out for the load capacity and stiffness of porous aerostatic bearing with different average aperture and surface compound restricted aerostatic bearing. The results show that applying the appropriate materials and processing methods can produce the aerostatic bearings with the higher load capacity and stiffness.

  5. The Design of The Journal Bearing of Dicing Saw's Aerostatic Motorized Spindle%划片机空气静压电主轴径向轴承的设计

    Institute of Scientific and Technical Information of China (English)

    李战伟; 刘婷婷

    2012-01-01

    径向轴承是划片机空气静压电主轴的关键零件,径向轴承的结构及尺寸直接影响转轴的高速旋转精度及工作性能。采用表压比法对划片机空气静压电主轴径向轴承进行设计计算,确定径向轴承的结构参数。%The journal bearing is the key part of the dicing saw's aerostatic motorized spindle. The journal bearing's structure and dimension infiuent indirectly on the spindle's rotating precision and working capacity at high speed. The journal beating of dicing saw's aerostatic motorized spindle are designed and calculated through gauge pressure ratio method, and the journal bearing's structural parameters are determined.

  6. 大跨人行悬索桥非线性静风稳定性分析%Nonlinear aerostatic stability analysis of a long-span suspension pedestrian bridge

    Institute of Scientific and Technical Information of China (English)

    薛晓锋; 管青海; 胡兆同; 李加武; 刘健新

    2014-01-01

    The nonlinear aerostatic stability of a 420m-main-span suspension pedestrian bridge was analysed numerically.Based on aerostatic coefficients of the main girder measured in wind tunnel tests,nonlinear influences caused by the structure and aerostatic load were analysed by using incremental double iteration method.The results conclude as follows:the structure deformation varying with wind speed shows obvious nonlinearity,and the aerostatic instability mode is of the characteristic of space deformation of bending-twisting coupling mode;comparing with the highway bridge,the torsional stiffness of the bridge due to main cables accounts for a greater proportion of the stiffness of the long-span suspension pedestrian bridge.The critical wind velocity and the reason of aerostatic instability can be got by tracing the stress in the main cable with the variation of wind speed;nonzero initial wind attack angle can reduce the critical wind speed;central buckles and anti-wind cables can raise the critical wind speed.The aerostatic instability mode after the installation of central buckles is the bending-twisting coupling mode of main girder,and the aerostatic instability mode after adding the measure of anti-wind cables is the local structural buckling due to the wind cables and hangers stress relaxation.The results are beneficial to the further research of long span narrow bridge aerostatic stability.%基于风洞试验所测加劲梁静力三分力系数,在综合考虑静风荷载非线性、结构几何非线性基础上,采用双重迭代计算分析方法对主跨420 m大跨窄人行悬索桥进行静风稳定性全过程分析。结果表明,结构变形随风速变化呈明显非线性,静风失稳形态弯曲扭转空间耦合变形特征显著;较公路桥大跨人行悬索桥主缆提供的扭转刚度比重更大,跟踪两主缆跨中应力随风速变化情况可定义静风失稳临界风速及与分析静风失稳原因;非零初始风攻角会降

  7. 精密机床静压气体轴承静特性分析及基本参数的优化%Static Characteristics Analysis and Basic Parameters Optimization of Aerostatic Bearing for Precision Machine Tool

    Institute of Scientific and Technical Information of China (English)

    李树森; 郭永红; 朱赞彬; 曾剑锋

    2012-01-01

    对精密机床气体轴承静特性进行理论分析,运用有限元法将雷诺方程离散化,得到静压气体轴承的承载能力、刚度以及供气量的计算公式.对某精密机床小孔节流静压气体轴承的静态特性进行分析,得到供气压力、偏心率、节流孔直径和刚度以及承载能力之间的关系曲线;通过优化分析,得到精密机床主轴前后静压气体轴承优化的结构参数和操作参数.%The static characteristics of gas bearing for the precision machine tool were analyzed in theory, the Reynolds equation was discretized with the finite element method and the calculating formula of bearing capacity, stiffness and the amount of gas supply were got. The static characteristics of aerostatic bearing with orifice compensated for a precision ma chine tool were analyzed,the relation curves of gas supply pressure,eccentricity,orifice diameter stiffness and bearing ca pacity were got. By optimization analysis,the structure and operation parameters of aerostatic bearing for precision machine tool spindle were concluded.

  8. 钢管高速漏磁探伤静压气浮探靴理论研究%Research on Aerostatic Probe for Magnetic Flux Leakage Testing for Steel Pipe in High Testing Speed

    Institute of Scientific and Technical Information of China (English)

    姜现想; 康宜华; 伍剑波

    2012-01-01

    针对传统接触式钢管漏磁探靴高速扫查时因剧烈摩擦而带来的磨损、发热等诸多问题,提出一种新型静压气浮探靴结构,其原理是,气流经过布置在气浮探靴上的节流孔后在钢管表面形成一层气膜,消除了探靴与钢管之间的直接摩擦,实现了非接触式跟踪。分析了气浮探靴静态特性与结构参数的关系,并针对直径为130mm的钢管设计了相应的漏磁探伤气浮探靴。%In order to solve the problems caused by high magnetic flux leakage testing speed for steel pipes,an aerostatic probe was proposed and the relationship among the static characteristics and structure parameters was analyzed. Finally,an aerostatic probe for steel pipe with diameter of 130mm was designed. The novel probe is especially suitable for high testing speed for that the friction between the probe and the steel pipe is avoided by the air--film.

  9. Experimental Research on Stability of High-speed Aerostatic Bearing-Rotor System%供气压力对气体轴承-转子系统稳定性影响的实验研究

    Institute of Scientific and Technical Information of China (English)

    马文琦; 黄鑫; 刘海艳

    2012-01-01

    In order to overcome the problem that the aerostatic bearing-rotor system vibrates severely near the critical speed region,a large number of experimental studies about the effects of supply pressure on stability of high-speed aerostatic bearing-rotor system were carried out.In this paper,with turbine driven and the control of the electrical proportional valve,vibration of this system was tested and analyzed on various working conditions.The results demonstrate that the critical speed is increased with the increase of the bearing supply pressure.However,the change of the vibration amplitude is opposite,which is reduced with the increase of the bearing supply pressure.The method of secondary controlling the supply pressure can sufficiently inhibit the vibration amplitude of the critical speed region within a certain range,and the system stability can be corresponding improved.%为解决气浮轴承在经过临界转速的剧烈振动不稳定这一问题,进行了供气压力对气体轴承-转子系统稳定性影响的实验研究.基于涡轮驱动和电器比例阀压力控制,搭建了基于高速静压气体轴承-转子系统实验台,对不同供气压力工况组合下系统振动进行了测试与分析.结果表明:在一定供气压力范围内,临界转速值随着轴承供气压力增大而升高,振动幅值随着轴承供气压力增大而降低,合理控制临界转速区域附近供气压力可一定程度内抑制振动幅值,达到提高系统稳定性的目的.

  10. 台湾后龙溪桥风洞试验研究与静风响应分析%Wind tunnel testing study and aerostatic response analysis of houlongxi bridge in taiwan

    Institute of Scientific and Technical Information of China (English)

    许福友; 张哲; 李天飞; 石磊

    2009-01-01

    通过风洞试验研究了台湾后龙溪桥气动稳定性;获得了混凝土梁和钢梁两种断面发生涡振的条件、涡振锁定风速范围及涡振振幅;对自然界和风洞中的风轴和体轴异同进行了区分;实测了两种断面的静气动力系数;最后进行了非线性静风荷载响应分析.研究结果表明:实桥风速达到135 m/s,不会发生气动失稳;钢梁和混凝土梁断面+3°攻角时在均匀流场中会发生坚向和扭转涡振,扭转涡振风速锁定风速很高,而且范围很宽;在紊流度约为10%风场中,攻角在-3°~+3°范围内,未观测到明显涡振;南静风荷载引起的主梁附加攻角很小,风荷载非线性对主梁扭转位移和侧向位移影响很小,而对竖向位移影响相对较大,原因是竖向风荷载引起主缆刚度改变.%The aero-stability performance of Houlongxi Bridge in Taiwan was investigated via wind tunnel tests. The conditions for vortex induced vibration of concrete and steel deck sections, as well as the lock-in wind velocity regions and vibration amplitudes were obtained. The similarity and discrepancy between the wind-axis and the body-axis in natural field and wind tunnel were expounded and discriminated. Then the aerostatic force coefficients were measured. The non- linear aerostatic response analysis was conducted finally. The study results revealed that the real bridge will not diverge when the velocity attains13.5m/s; in smooth flows, vertical bending and torsional vortex vibration occur for two models with +3° attack angle; for torsional vortex vibration,the wind velocity is quite high and its lock-in region is wide; in flows with turbulence intensity of 10%, when attack angle varies form -3° to + 3°, no apparent vortex can be observed; the deck added attack angle incurred by static wind loads is very tiny; the wind load non-linearity plays negligible role on deck torsional and lateral displacement; as the vertical lift wind loads will cause the

  11. Experimental Study on Rub-impact Faults of High-speed Aerostatic Bearing-rotor Systems%高速气体轴承-转子系统碰磨故障的试验

    Institute of Scientific and Technical Information of China (English)

    付忠广; 边技超; 杨金福

    2015-01-01

    建立单跨、四圆盘结构的高速气体静压轴承-转子系统试验台,对系统的碰磨故障进行了试验研究。在试验过程中,呈现了轴向碰磨与径向碰磨,低频引起的碰磨与工频引起的碰磨等碰磨故障现象,通过分析系统振动信号的频谱特性、轴心运动轨迹、分岔图、伯德图及时间-频率-幅值三维谱图等给出了各种碰磨故障的典型特征,并分析了轴向碰磨与径向碰磨,低频引起的碰磨与工频引起的碰磨等碰磨故障之间的特征区别。为碰磨故障的识别与碰磨故障诊断系统的建立提供了一些试验依据。%The test bench for high-speed aerostatic bearing-rotor systems with single span and four disks structure was built, and the rub-impact faults of the systems were studied experimentally. The axial rub-impact and radial rub-impact at low frequency and working frequency were tested. Through the analyses of the frequency spectrum characteristics, shaft cen-ter kinetic trajectory, bifurcation diagram and time-frequency-amplitude waterfall diagrams, the typical features of all kinds of rub-impact faults were given. Meanwhile, the difference of the faults was analyzed. The work may provide a data base for rub-impact fault identification and the establishment of the diagnosis systems.

  12. 多箱渡槽槽身静风三分力系数风洞试验研究%A wind tunnel test study on aerostatic coefficients of large scale multi-box aqueduct bridge deck

    Institute of Scientific and Technical Information of China (English)

    李遇春; 邸庆霜; 张文杰; 张婷婷

    2012-01-01

    A wind tunnel test for the six scaled multi-box aqueduct decks (including 3 two-box and 3 three-box models) was conducted. The cases with full and without water, and with different wind attack an- gles are considered respectively. The drag, lift and pitching moment coefficients of multi-box aqueduct decks were obtained by the test result analyses. The surface pressure distributions and the aerostatic coeffi- cients of the test models were displayed and discussed. The results show that: (1) The wind flow field around multi-box aqueduct deck is similar to that of blunt body; (2) The drag force is the most important wind load among the three static loads; (3) The drag coefficient decreases with the increasing of width/ height ratio of aqueduct decks in the whole tendency.%对6个多箱式渡槽槽身刚性测压模型进行了风洞试验研究,分别模拟了满槽、空槽以及不同风攻角的试验工况。根据试验结果得到了槽身模型的静风三分力(阻力、升力和扭矩)系数,讨论了模型风压分布以及三分力系数的变化规律。试验结果表明:(1)多箱式渡槽槽身绕流更趋近于钝体绕流;(2)槽身风荷载主要表现为风阻力;(3)阻力系数在总体趋势上随着槽截面宽高比的增加而减小。试验结果可为多箱渡槽的抗风研究与设计提供初步的参考。

  13. On The Modelling Of Hybrid Aerostatic - Gas Journal Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2011-01-01

    Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... modeling for hybrid lubrication of a compressible fluid film journal bearing. Additional forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving...... this equation, stiffness and damping coefficients can be determined. A multibody dynamics model of a global system comprised of rotor and hybrid journal bearing is built in order to study the lateral dynamics of the system. Campbell diagrams and stability maps are presented, showing the main advantages...

  14. On The Modeling Of Hybrid Aerostatic - Gas Journal Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2010-01-01

    Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... of a compressible fluid film journal bearing. Control forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving this equation, stiffness and damping...... conventional oil bearings, carrying capacity and dynamic characteristics of passive systems are generally poorer. In order to enhance these characteristics, one solution is to employ active control strategies. The present contribution presents a detailed mathematical modeling for active lubrication...

  15. On the stability analysis of flexible rotors supported by Hybrid Aerostatic - Gas Journal Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    Modern turbo-machinery applications, high speed machine tools, laboratory equipment require nowadays ever-growing rotational speeds and high degree of precision and reliability. Gas journal bearing have been in many extents employed as they meet the demands of performing at high speeds, in clean...

  16. 浮空器氦气纯化方法应用研究%Research on application of aerostat helium purification method

    Institute of Scientific and Technical Information of China (English)

    万小刚; 傅剑; 赵林华

    2011-01-01

    在浮空器使用过程中,外界空气的混入将导致其内部氦气纯度降低,从而影响到浮空器正常使用.文中通过对常用气体分离方法的分析研究,提出了以高压低温冷凝和低温吸附相结合的方式作为浮空器氦气提纯方式的思路,并详细给出了实现工艺流程和控制方案.换热计算结果表明:该纯化方法液氮消耗量小、氦气提纯成本低.%Aerostat’s working capability is influenced when atmosphere mixed into its envelope and debased the inner helium purity. Through analysis of general gas separation methods, this paper presented a kind of high - pressure condensation and adsorption method as aerostat’s heiium purification way, detailed working flow and control scheme were also presented. Heat exchange calculation shows that, this method costs low liquid nitrogen and low expense.

  17. 飞艇续航时间论证方法研究%Study of Airborne Endurance Analyzing Method of Tethered Aerostat

    Institute of Scientific and Technical Information of China (English)

    姜琬

    2013-01-01

    由于飞艇续航时间受飞行速度、重力浮力配平方式、载油量变化、风场条件等多种因素的影响,飞机续航时间计算方法并不适用于飞艇,因此提出了一种新的基于试验设计和统计分析方法的飞艇续航时间论证方法。分析了工作高度的风场速度分布规律,分别给出完全靠发动机推力矢量平衡和完全靠动升力平衡两种不同情况下飞艇续航时间计算方法,以某大型对流层飞艇为研究对象,计算了初始方案在不同平均巡航速度、配平重量和配平方式下的平均燃油消耗率和最大续航时间,对经过减阻、减重、减少耗油率等技术改进后优化方案能达到的续航时间和概率进行了分析和论证。研究表明,某飞艇初始方案在使用区域风场条件下基本能满足留空时间72 h的指标要求,经技术改进后,指标仍有较大的提升的空间。方法考虑了飞艇续航时间的多种影响因素、取值变化和交互影响,比较适宜在飞艇这类涉及重浮力配平和任务耗油率变化的浮空器上使用。%The cruise duration calculating method of aircraft is not suitable for airship because airship ′s endurance in flight is influenced by many factors , such as velocity , balance of weight and buoyancy , change of fuel load and wind condition ,and therefore a new endurance analyzing method according to air-ship on the basis of experiment design and statistic analysis means is presented .Firstly,the wind velocity distributing regulation at working altitude is analyzed .Then two kinds of airship endurance calculating methods under different conditions are given respectively ,including power plant thrust vector counterbal-ance and aerodynamic lift counterbalance .After that,taking a large troposphere airship as study object , the average fuel consumption and maximum endurance of its primary scheme at different average cruise velocity,trim weight and means are calculated .At last,the endurance capacity and probability of the opti-mized scheme after technique improvement with drag , weight and fuel consumption decreasing are ana-lyzed and demonstrated .The study indicated that the primary scheme of the airship can basically meet the requirement of 72 h airborne endurance index with the given wind condition in the application region ,and the index can be further prolonged after technique improvement .The method takes into account multifari-ous influencing factors of airship endurance ,change of partial factor values and interaction between fac-tors,and is propitious to be used in the counterpart like airships which referring balance of weight and buoyancy ,together with task fuel consumption change .

  18. Power Gyroscopes of Stabilizing System

    OpenAIRE

    Šimek, Jiří; Šklíba, Jan; Sivčák, Michal; Škoda, Jan

    2011-01-01

    The paper deals with problems concerning power gyroscopes for stabilization of vibro-izolation system. Two variants of gyro support with air drive were designed, namely with gas bearings and precision rolling bearings. Precession frame of the gyro is supported in aerostatic journal bearings to achieve minimum passive resistance. Some special phenomena, such as pneumatic instability, were found in some test regimes both at aerostatic thrust bearing of gyro support and aerostatic journal bearin...

  19. Analysis of Orifice Compensated Mode Affecting Aerostatic Bearing's Working Stiffness%小孔节流方式对气体静压轴承工作刚度影响的分析

    Institute of Scientific and Technical Information of China (English)

    李树森; 刘暾; 张鹏顺

    2000-01-01

    本文对小孔节流方式中的简单孔节流和环形孔节流形式对气体静压轴承工作刚度的影响进行了理论分析,通过比较从而得出,采用简单孔节流方式的轴承比环形孔节流方式的轴承具有更高的工作刚度.

  20. Design and Implementation of Software for Mobile Tethered Aerostat Measure and Control System%机动式系留气球测控系统软件设计与实现

    Institute of Scientific and Technical Information of China (English)

    唐黎江

    2013-01-01

    This paper first introduces content of real-time operation system and tethered airship measure and control system. It explains and analyses the composition and characteristic of tethered airship. On the basis of the properties of function, this paper introduce detailedly the process of the design and the implement of software structure of tethered airship measure and control system, and software designed process is also given. The application of software in actual system proved the feasibility, reliability and character of real-time.%介绍了VxWorks实时操作系统、系留气球测控系统的相关内容,阐述并分析了系留气球的组成和特点.根据系留气球测控系统的功能,详细介绍了系留气球测控系统软件的设计和实现过程,给出了软件设计的流程图,并通过在实际系统中的应用,验证了软件的可行性、可靠性和实时性.

  1. The Role of Unmanned Aerial Systems-Sensors in Air Quality Research

    Science.gov (United States)

    The use of unmanned aerial systems (UASs) and miniaturized sensors for a variety of scientific and security purposes has rapidly increased. UASs include aerostats (tethered balloons) and remotely controlled, unmanned aerial vehicles (UAVs) including lighter-than-air vessels, fix...

  2. СИНТЕЗ АЛГОРИТМУ ОПТИМАЛЬНОГО КЕРУВАННЯ РУХОМ АЕРОСТАТИЧНОГО ЛІТАЛЬНОГО АПАРАТА НА ЕТАПІ ПОСАДКИ

    OpenAIRE

    ГУСИНІН Андрій Вячеславович

    2013-01-01

    The automated control algorithm by aerostatic vehicle thrust vector tilting at landing stage was synthesized. The possibility and effectiveness of synthesized control algorithm by thrust vector tilting was presented by simulation of airship «Zeppelin NT» landing.

  3. The Role of Unmanned Aerial Systems/Sensors in Air Quality Research

    Science.gov (United States)

    The use of unmanned aerial systems (UASs) for a variety of scientific and security purposes has rapidly increased. UASs include aerostats (tethered balloons) and remotely controlled, unmanned aerial vehicles (UAVs) including lighter-than-air vessels, fixed wing airplanes, and he...

  4. Experimental investigations of active air bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar; Morosi, Stefano

    2012-01-01

    Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso-scal...

  5. СИНТЕЗ АЛГОРИТМУ ОПТИМАЛЬНОГО КЕРУВАННЯ РУХОМ АЕРОСТАТИЧНОГО ЛІТАЛЬНОГО АПАРАТА НА ЕТАПІ ПОСАДКИ

    Directory of Open Access Journals (Sweden)

    ГУСИНІН Андрій Вячеславович

    2013-06-01

    Full Text Available The automated control algorithm by aerostatic vehicle thrust vector tilting at landing stage was synthesized. The possibility and effectiveness of synthesized control algorithm by thrust vector tilting was presented by simulation of airship «Zeppelin NT» landing.

  6. Investigation of Kevlar fabric-based materials for use with inflatable structures

    Science.gov (United States)

    Niccum, R. J.; Munson, J. B.; Rueter, L. L.

    1977-01-01

    Design, manufacture and testing of laminated and coated composite materials incorporating a structural matrix of Kevlar are reported. The practicality of using Kevlar in aerostat materials is demonstrated, and data are provided on practical weaves, lamination and coating particulars, rigidity, strength, weight, elastic coefficients, abrasion resistance, crease effects, peel strength, blocking tendencies, helium permeability, and fabrication techniques. Properties of the Kevlar-based materials are compared with conventional Dacron-reinforced counterparts. A comprehensive test and qualification program is discussed, and considerable quantitative biaxial tensile and shear test data are provided.

  7. The balloon and the airship technological heritage

    Science.gov (United States)

    Mayer, N. J.

    1981-01-01

    The balloon and the airship are discussed with emphasis on the identification of commonalities and distinctions. The aerostat technology behind the shape and structure of the vehicles is reviewed, including a discussion of structural weight, internal pressure, buckling, and the development of a stable tethered balloon system. Proper materials for the envelope are considered, taking elongation and stress into account, and flight operation and future developments are reviewed. Airships and tethered balloons which are designed to carry high operating pressure with low gas loss characteristics are found to share similar problems in low speed flight operations, while possessing interchangeable technologies.

  8. Design aspects of zeppelin operations from case histories

    Science.gov (United States)

    Maiersperger, W. P.

    1975-01-01

    Some widely held beliefs concerning the practicability of rigid airships in air carrier operations are discussed. It is shown by a review of past operational experience, and some basic aerostatic theory, their actual record and the reasons for their demise. Problems of atmospheric density and temperature variations, meteorological factors, aerodynamic stability and control, and mooring difficulties are discussed and related to actual case histories. Structural and flight efficiencies are compared to airplane efficiencies for airplanes contemporary with the zeppelin as well as modern designs. The difficulty of supporting new, commercial airship developments on an economic basis is made clear.

  9. Raman lasing in a hollow, bottle-like microresonator

    CERN Document Server

    Ooka, Yuta; Ward, Jonathan; Chromaic, Síle Nic

    2015-01-01

    We report on the fabrication of an ultrahigh quality factor, bottle-like microresonator from a hollow microcapillary, and the realisation of Raman lasing therein at pump wavelengths of $1.55~\\mathrm{\\mu m}$ and $780~\\mathrm{nm}$. Third-order cascaded Raman lasing was observed when pumped at $780~\\mathrm{nm}$. The aerostatic pressure tunability of the Raman laser was also investigated. Thence, we demonstrate that a high dynamic range, high resolution pressure sensor can be realised using the Raman spectrum of the hollow, bottle-like microresonator.

  10. The centering and leveling adjustment and control technology for the ultra-precision turntable

    Science.gov (United States)

    Tian, Yanrong; Wang, Yun; Wang, Longxiao; Zhao, Weirui

    2015-08-01

    In order to realize the centering and leveling adjustment in large aperture spherical and aspheric surface shape measurement, by combining with the aerostatic bearing rotary shaft, working platform, high performance servo motor, photoelectric encoder, the micro displacement actuator of XYZ axis, sensor and Renishaw circular grating ,a set of fast and ultra-precision centering and leveling adjustment system is developed .The system is based on large range of air lubrication technology for high precision aerostatic bearing turntable, using the principle of three point supporting method, and the driving of tens nanometer resolution are provided by a piezoelectric micro displacement actuator. To realize the automatical centering and leveling adjustment in the large aperture spherical and aspheric surface shape measurement system, a software control program is designed with VC++. Through experimental test: centering adjusting operation can eventually converges to 0.5μm, leveling adjusting operation can eventually converges to 0.2 ", the time of adjusting can be less than 120 s. The experimental results shows that, compared with the previous system, the structure of the developed measurement and control system is more simple, more flexible, it can meet the demands of high precision, high resolution, large adjusting range, no friction, easy to drive, and high bearing stiffness etc in eccentric adjusting operation of optical precision measurement well.

  11. To sail the skies of Mars - Scientific ballooning on the red planet

    Science.gov (United States)

    Gaidos, Eric J.; Burke, James D.

    1988-01-01

    Balloons represent a novel approach to exploring the surface of Mars. One promising aerostat system incorporates a solar-powered balloon as a means of generating diurnally varying lift and so can 'hop' across the surface, obtaining detailed information at a large number of sites. Two important areas of research and testing are underway on solar balloon technology and balloon payload design. The solar balloon concept has been demonstrated on earth, but more work is needed on a 'flyable' version for Mars. Particular attention must be paid to radiation heat transfer and aerodynamic effects. A special 'snake' payload concept has been demonstrated that allows for balloon system traverses of the surface and provides a usable instrument platform. A balloon system of this type could obtain unique surface imaging and physical and chemical data. The flight of the balloon also provides in situ atmospheric boundary-layer and circulation measurements.

  12. Balloon concepts for scientific investigation of Mars and Jupiter

    Science.gov (United States)

    Ash, R. L.

    1979-01-01

    Opportunities for scientific investigation of the atmospheric planets using buoyant balloons have been explored. Mars and Jupiter were considered in this study because design requirements at those planets bracket nominally the requirements at Venus, and plans are already underway for a joint Russian-French balloon system at Venus. Viking data has provided quantitative information for definition of specific balloon systems at Mars. Free flying balloons appear capable of providing valuable scientific support for more sophisticated Martian surface probes, but tethered and powered aerostats are not attractive. The Jovian environment is so extreme, hot atmosphere balloons may be the only scientific platforms capable of extended operations there. However, the estimated system mass and thermal energy required are very large.

  13. The Identification of Nonlinear Systems Using Ct-Kt Plane Coordinates

    Directory of Open Access Journals (Sweden)

    Ming-Fei Chen

    2014-01-01

    Full Text Available In order to instantaneously distinguish the Ct (coefficient of viscous damping and Kt (coefficient of stiffness, which are both functions of time in an M.C.K. nonlinear system, a new identification method is proposed in this paper. The graphs of the Ct-Kt are analyzed and the dynamic behavior of M.C.K. systems in a Ct-Kt coordinate plane is discussed. This method calculates two adjacent sampling data, the displacement, velocity, and acceleration (which are obtained from the responses of a pulse response experiment and then distinguishes Ct and Kt of an instantaneous system. Finally, this method is used to identify the aerostatic bearing dynamic parameters, C and K.

  14. Investigation of Kevlar fabric based materials for use with inflatable structures

    Science.gov (United States)

    Niccum, R. J.; Munson, J. B.

    1974-01-01

    Design, manufacture and testing of laminated and coated composite materials incorporating a structural matrix of Kevlar are reported in detail. The practicality of using Kevlar in aerostat materials is demonstrated and data are provided on practical weaves, lamination and coating particulars, rigidity, strength, weight, elastic coefficients, abrasion resistance, crease effects, peel strength, blocking tendencies, helium permeability, and fabrication techniques. Properties of the Kevlar based materials are compared with conventional, Dacron reinforced counterparts. A comprehensive test and qualification program is discussed and quantitative biaxial tensile and shear test data are provided. The investigation shows that single ply laminates of Kevlar and plastic films offer significant strength to weight improvements, are less permeable than two ply coated materials, but have a lower flex life.

  15. Power generation on a solar photovoltaic modules integrated Lighter-than-Air Platform at a low altitude

    CERN Document Server

    Ghosh, Kuntal; Duttagupta, Siddharth P

    2016-01-01

    Use of lighter than air platforms (aerostats and airships) for reconnaissance and surveillance over long periods can be facilitated by generation of power on-board through solar photovoltaic arrays. Attempts to integrate solar photovoltaic modules on such contoured surfaces leads to multiple challenges ranging from the choice of solar modules, determination of best method of their integration with the lighter than air platform, and design of the array layout in order to optimize the loss of power due to non-uniform illumination. This paper describes the method of designing such a system and suggests strategies for overcoming these challenges. The issue of non-uniform illumination has been tackled by maximum power point tracking using the scanning window technique for maximizing power generation and an algorithm of distributed maximum power point tracking has been suggested for further improvement. The procedure described in this paper can be used for obtaining the optimum power generation capability of a sola...

  16. Oil-free bearing development for high-speed turbomachinery in distributed energy systems - dynamic and environmental evaluation

    Science.gov (United States)

    Tkacz, Eliza; Kozanecka, Dorota; Kozanecki, Zbigniew; Łagodziński, Jakub

    2015-09-01

    Modern distributed energy systems, which are used to provide an alternative to or an enhancement of traditional electric power systems, require small size highspeed rotor turbomachinery to be developed. The existing conventional oil-lubricated bearings reveal performance limits at high revolutions as far as stability and power loss of the bearing are concerned. Non-conventional, oil-free bearings lubricated with the machine working medium could be a remedy to this issue. This approach includes a correct design of the machine flow structure and an accurate selection of the bearing type. Chosen aspects of the theoretical and experimental investigations of oil-free bearings and supports; including magnetic, tilting pad, pressurized aerostatic and hydrostatic bearings as well as some applications of oil-free bearing technology for highspeed turbomachinery; are described in the paper.

  17. Aerial Delivery Systems and Technologies (Review Paper

    Directory of Open Access Journals (Sweden)

    Balraj Gupta

    2010-03-01

    Full Text Available Aerial Delivery Research & Development Establishment (ADRDE was started at Kanpur during latter part of 1950's consisting of two Aerial Delivery Sections primarily for the indigenisation of Parachutes and related equipment for Para-dropping of men and materials. Today, the charter of ADRDE includes design & development of parachutes, Aerostat Systems, Aircraft Arrester Barrier Systems and Heavy-Drop Systems for both military and civilian applications. The technological competence built in Aeronautical, Textile, Mechanical and Electronics engineering has imparted ADRDE, a unique combination of know-how and capabilities to evolve new solutions in these fields, with emphasis on quality assurance. This paper highlights the design and development of technologies developed by ADRDE to stengthen the India's aerial delivery system and its future plans.Defence Science Journal, 2010, 60(2, pp.124-136, DOI:http://dx.doi.org/10.14429/dsj.60.326

  18. High-speed impact test using an inertial mass and an optical interferometer.

    Science.gov (United States)

    Jin, T; Watanabe, K; Prayogi, I A; Takita, A; Mitatha, S; Djamal, M; Jia, H Z; Hou, W M; Fujii, Y

    2013-07-01

    A high-speed impact testing method for evaluating mechanical properties of materials is proposed using an inertial mass and a dual beat-frequencies laser Doppler interferometer (DB-LDI). In this method, an inertial mass levitated using an aerostatic linear bearing is made to collide with the material being tested at a high initial velocity. During the collision, the velocity of the mass, which is even higher than the critical velocity (±0.56 m/s) defined by the frequency difference of the Zeeman laser, is accurately measured using the DB-LDI. The position, acceleration, and impact force of the mass are calculated from the measured velocity. Using the proposed method, the mechanical properties of a visco-elastic material under a high-speed impact loading condition can be accurately evaluated.

  19. Power Laser Ablation Symposia

    CERN Document Server

    Phipps, Claude

    2007-01-01

    Laser ablation describes the interaction of intense optical fields with matter, in which atoms are selectively driven off by thermal or nonthermal mechanisms. The field of laser ablation physics is advancing so rapidly that its principal results are seen only in specialized journals and conferences. This is the first book that combines the most recent results in this rapidly advancing field with authoritative treatment of laser ablation and its applications, including the physics of high-power laser-matter interaction. Many practical applications exist, ranging from inertial confinement fusion to propulsion of aerostats for pollution monitoring to laser ignition of hypersonic engines to laser cleaning nanoscale contaminants in high-volume computer hard drive manufacture to direct observation of the electronic or dissociative states in atoms and molecules, to studying the properties of materials during 200kbar shocks developed in 200fs. Selecting topics which are representative of such a broad field is difficu...

  20. Tunable erbium-doped microbubble laser fabricated by sol-gel coating

    CERN Document Server

    Yang, Yong; Kasumie, Sho; Xu, Linhua; Ward, Jonathan; Yang, Lan; Chormaic, Síle Nic

    2016-01-01

    In this work, we show that the application of a sol-gel coating renders a microbubble whispering gallery resonator into an active device. During the fabrication of the resonator, a thin layer of erbium-doped sol-gel is applied to a tapered microcapillary, then a microbubble with a wall thickness of 1.3 $\\mu$m is formed with the rare earth diffused into its walls. The doped microbubble is pumped at 980 nm and lasing in the emission band of the Er$^{3+}$ ions with a wavelength of 1535 nm is observed. The laser wavelength can be tuned by aerostatic pressure tuning of the whispering gallery modes of the microbubble. Up to 240 pm tuning is observed with 2 bar of applied pressure. It is shown that the doped microbubble could be used as a compact, tunable laser source. The lasing microbubble can also be used to improve sensing capabilities in optofluidic sensing applications.

  1. Oil-free bearing development for high-speed turbomachinery in distributed energy systems – dynamic and environmental evaluation

    Directory of Open Access Journals (Sweden)

    Tkacz Eliza

    2015-09-01

    Full Text Available Modern distributed energy systems, which are used to provide an alternative to or an enhancement of traditional electric power systems, require small size highspeed rotor turbomachinery to be developed. The existing conventional oil-lubricated bearings reveal performance limits at high revolutions as far as stability and power loss of the bearing are concerned. Non-conventional, oil-free bearings lubricated with the machine working medium could be a remedy to this issue. This approach includes a correct design of the machine flow structure and an accurate selection of the bearing type. Chosen aspects of the theoretical and experimental investigations of oil-free bearings and supports; including magnetic, tilting pad, pressurized aerostatic and hydrostatic bearings as well as some applications of oil-free bearing technology for highspeed turbomachinery; are described in the paper.

  2. Airships: A New Horizon for Science

    CERN Document Server

    Miller, Sarah H; Hillenbrand, Lynne; Rhodes, Jason; Baird, Gil; Blake, Geoffrey; Booth, Jeff; Carlile, David E; Duren, Riley; Edworthy, Frederick G; Freeze, Brent; Friedl, Randall R; Goldsmith, Paul F; Hall, Jeffery L; Hoffman, Scott E; Hovarter, Scott E; Jensen-Clem, Rebecca M; Jones, Ross M; Kauffmann, Jens; Kiessling, Alina; King, Oliver G; Konidaris, Nick; Lachenmeier, Timothy L; Lord, Steven D; Neu, Jessica; Quetin, Gregory R; Ram, Alan; Sander, Stanley; Simard, Marc; Smith, Mike; Smith, Steve; Smoot, Sara; Susca, Sara; Swann, Abigail; Young, Eliot F; Zambrano, Thomas

    2014-01-01

    The "Airships: A New Horizon for Science" study at the Keck Institute for Space Studies investigated the potential of a variety of airships currently operable or under development to serve as observatories and science instrumentation platforms for a range of space, atmospheric, and Earth science. The participants represent a diverse cross-section of the aerospace sector, NASA, and academia. Over the last two decades, there has been wide interest in developing a high altitude, stratospheric lighter-than-air (LTA) airship that could maneuver and remain in a desired geographic position (i.e., "station-keeping") for weeks, months or even years. Our study found considerable scientific value in both low altitude ( 60 kft) airships across a wide spectrum of space, atmospheric, and Earth science programs. Over the course of the study period, we identified stratospheric tethered aerostats as a viable alternative to airships where station-keeping was valued over maneuverability. By opening up the sky and Earth's strato...

  3. Figurative lights: Images of Techno-Scientific slides and Secularization in Spain during the 18th Century

    Directory of Open Access Journals (Sweden)

    Germán LABRADOR MÉNDEZ

    2010-06-01

    Full Text Available This paper asembles and studies a set of iconological representations linked to technical and scientific transformations during the eighteenth Century in Spain, reading them in a dialectic between modern science, Enlightenment policies and popular culture. After analyzing the emergence of representations both of science and scientists according to the process of institutionalizing science as a socio-professional language, two specific eighteenth century technologies are studied: magic lanterns and aerostats. By interpreting their first images and their infiltration into popular and official speeches and the imagination of the moment, it is argued that in those images a tale of demo-Enlightenment is expressed, a tale about secularization and progress as a collective aesthetic experience.

  4. Bridging Informatics and Earth Science: a Look at Gregory Leptoukh's Contributions

    Science.gov (United States)

    Lynnes, C.

    2012-12-01

    With the tragic passing this year of Gregory Leptoukh, the Earth and Space Sciences community lost a tireless participant in--and advocate for--science informatics. Throughout his career at NASA, Dr. Leptoukh established a theme of bridging the gulf between the informatics and science communities. Nowhere is this more evident than his leadership in the development of Giovanni (GES DISC Interactive Online Visualization ANd aNalysis Infrastructure). Giovanni is an online tool that serves to hide the often-complex technical details of data format and structure, making science data easier to explore and use by Earth scientists. To date Giovanni has been acknowledged as a contributor in 500-odd scientific articles. In recent years, Leptoukh concentrated his efforts on multi-sensor data inter-comparison, merging and fusion. This work exposed several challenges at the intersection of data and science. One of these was the ease with which a naive user might generate spurious comparisons, a potential hazard that was the genesis of the Multi-sensor Data Synergy Advisor (MDSA). The MDSA uses semantic ontologies and inference rules to organize knowledge about dataset quality and other salient characteristics in order to advise users on potential caveats for comparing or merging two datasets. Recently, Leptoukh also led the development of AeroStat, an online Giovanni instance to investigate aerosols via statistics from station and satellite comparisons and merged maps of data from more than one instrument. Aerostat offers a neural net based bias adjustment to "harmonize" the data by removing systematic offsets between datasets before merging. These examples exhibit Leptoukh's talent for adopting advanced computer technologies in the service of making science data more accessible to researchers. In this, he set an example that is at once both vital and challenging for the ESSI community to emulate.

  5. Bridging Informatics and Earth Science: a Look at Gregory Leptoukh's Contributions

    Science.gov (United States)

    2012-01-01

    With the tragic passing this year of Gregory Leptoukh, the Earth and Space Sciences community lost a tireless participant in--and advocate for--science informatics. Throughout his career at NASA, Dr. Leptoukh established a theme of bridging the gulf between the informatics and science communities. Nowhere is this more evident than his leadership in the development of Giovanni (GES DISC Interactive Online Visualization ANd aNalysis Infrastructure). Giovanni is an online tool that serves to hide the often-complex technical details of data format and structure, making science data easier to explore and use by Earth scientists. To date Giovanni has been acknowledged as a contributor in 500-odd scientific articles. In recent years, Leptoukh concentrated his efforts on multi-sensor data inter-comparison, merging and fusion. This work exposed several challenges at the intersection of data and science. One of these was the ease with which a naive user might generate spurious comparisons, a potential hazard that was the genesis of the Multi-sensor Data Synergy Advisor (MDSA). The MDSA uses semantic ontologies and inference rules to organize knowledge about dataset quality and other salient characteristics in order to advise users on potential caveats for comparing or merging two datasets. Recently, Leptoukh also led the development of AeroStat, an online Giovanni instance to investigate aerosols via statistics from station and satellite comparisons and merged maps of data from more than one instrument. Aerostat offers a neural net based bias adjustment to harmonize the data by removing systematic offsets between datasets before merging. These examples exhibit Leptoukh's talent for adopting advanced computer technologies in the service of making science data more accessible to researchers. In this, he set an example that is at once both vital and challenging for the ESSI community to emulate.

  6. Wind stability of three-tower suspension bridges under construction%三塔悬索桥施工过程抗风稳定性研究

    Institute of Scientific and Technical Information of China (English)

    张新军; 郭辉

    2011-01-01

    Taking the first three-tower suspension bridge in the world with a main span over 1000 meters - the Taizhou Highway Bridge over the Yangtze River as example, for three different construction sequences of the deck, erected symmetrically from the midpoints of the main spans to the pylons, from the pylons toward the midpoints of the main spans, and simultaneously from the pylons and the midpoints of the main spans toward the quarter points of the main spans, respectively, evolutions of the structural aerostatic and aerodynamic stability during the deck erection process are investigated numerically by 3-1) nonlinear aerostatie and aerodynamic analysis, and the favorable deck erection sequence is discussed with respect to wind stability. The results show that the best aerostatic and aerodynamic stability is achieved under the deck erection sequence of pylons to midspans, which is considered to be favorable for three-tower suspension bridges.%以目前世界首座跨度超千米的三塔悬索桥——泰州长江公路大桥为工程背景,分别模拟主梁从主跨跨中向两侧桥塔、从两侧桥塔向主跨跨中以及从两侧桥塔和主跨跨中同时向主跨四分点处对称拼装的施工顺序,采用三维非线性空气静力和动力稳定性分析方法,分析主梁拼装过程结构的空气静力和动力稳定性的演变规律,并从抗风稳定性角度提出三塔悬索桥适宜的主梁拼装施工顺序。结果表明:主梁从两侧桥塔向主跨跨中对称拼装施工时,结构的空气静力和动力稳定性最好,是大跨度三塔悬索桥一种适宜的主梁拼装施工顺序。

  7. 径向变体飞艇总体参数估算方法%Parameters estimation method of radial transformable airship

    Institute of Scientific and Technical Information of China (English)

    肖治垣; 郦正能

    2012-01-01

    To break the crucial technical difficulties of controllable aerostat in near space,and make it possible of controlling aerostat going and returning between ground and near space,the conception of solar powered radial transformable airship was raised,and it’s parameters estimation method was given.The method was based on Archimedes theory and Li-style transformable airship theory.The self-adapting and controllable-transformation of sectional area was actualized by radial transformation of structure,net lift was changed by controlling the volume of airship.Controllable aerodynamic configuration was consistently kept through the change of volume,thereby the controls for ascending,descending and staying of airship were actualized.Size of inside ballonet and outside ballonet were accounted by designing transformation project,length of airship was accounted by analyzing dynamics balance and energy balance.Based on study out design parameter,an overall design project for solar powered radial transformable airship was given,feasibility and practicality of the method was validated by example.%为突破临近空间可操纵浮空器的关键技术难点,使可操纵浮空器往返地面至临近空间成为可能,提出了一种径向变体飞艇的总体参数估算方法,该方法基于阿基米德浮力定律和李式变体飞艇原理(Li-Style Transformable Airship Theory),通过艇体结构的径向变形来实现艇体截面积的自适与可控变化,控制飞艇容积变化以改变净升力大小,并使飞艇在容积变化中始终保持可操纵的气动外形,从而实现飞艇的升、降与驻空和飞行等控制.通过设计变形方案估算内气囊与外气囊尺寸,分析力学平衡与能源平衡估算飞艇长度.在拟定设计参数的基础上,给出了一种太阳能径向变体飞艇的总体设计方案,并通过设计实例验证了此方法的可行性与实用性.

  8. Two hundred years of flight in America: A bicentennial survey

    Science.gov (United States)

    Emme, E. M.

    1977-01-01

    The first recorded balloon ascension in America took place on June 19, 1784, when an unmanned balloon was raised in a public demonstration at Bladensburg, Maryland. On June 24, 1784, a thirteen-year-old boy ascended in the same balloon. The history of actual flight during the nineteenth century was entirely concerned with balloons except for several gliders and models leading to the coming of the airship and the aircraft. The history of practical flight in America begins in the twentieth century. The described developments related to aerostatics are concerned with balloons, rigid airships, and blimps. In a review of the evolution of aeronautics, attention is given to general aviation and its search for a market, trends in military aeronautics, and commercial aviation. It is pointed out that American air transport had its birth on New Year's Day, 1914, at Tampa Bay, Florida. The evolution of astronautics during the period from 1957 to 1976 is also examined, taking into account scientific satellites, the Apollo project, the exploration of the planets with the aid of unmanned spacecraft, strategic reconnaissance satellites, missile alarm satellites, instrumental satellites for detecting nuclear and thermonuclear explosions, weather satellites, communications satellites, and earth resource survey and geodetic satellites.

  9. Study on the Aerodynamic Characteristics of a Single-pylon Cable-stayed Bridge Girder by Numerical Simulation and Wind Tunnel Test

    Directory of Open Access Journals (Sweden)

    Longqi Zhang

    2014-09-01

    Full Text Available The wind induced vibration is one of the key technical problems for long-span bridge design. Therefore, a study on the aerodynamic characteristics of a single-pylon cable-stayed bridge girder is carried out in this paper. The aerostatic coefficient of the bridge girder, including both construction state and service state, is investigated by wind tunnel test with varying wind attack angle. Then based on the computational fluid dynamics (CFD method, the flow field around the bridge girder is visualized numerically. The risk of vortex-induced vibration (VIV is qualitatively evaluated by analyzing the flow features and by considering the Scruton number (Sc. Later a dynamic section model is tested in wind tunnel and the VIV phenomenon is observed subsequently. Results show that the aerodynamic stability is assured by the positive slope of the lift coefficient. The VIV response is influenced by the structural damping and the bridge accessory. The amplitude of VIV response can be lower by increasing the structural damping. The maintenance track rail of the bridge girder also does some good for suppressing the VIV as long as the track rail is located at the appropriate place.

  10. Numerical Modelling Of Pumpkin Balloon Instability

    Science.gov (United States)

    Wakefield, D.

    Tensys have been involved in the numerical formfinding and load analysis of architectural stressed membrane structures for 15 years. They have recently broadened this range of activities into the `lighter than air' field with significant involvement in aerostat and heavy-lift hybrid airship design. Since early 2004 they have been investigating pumpkin balloon instability on behalf of the NASA ULDB programme. These studies are undertaken using inTENS, an in-house finite element program suite based upon the Dynamic Relaxation solution method and developed especially for the non-linear analysis and patterning of membrane structures. The paper describes the current state of an investigation that started with a numerical simulation of the lobed cylinder problem first studied by Calladine. The influence of material properties and local geometric deformation on stability is demonstrated. A number of models of complete pumpkin balloons have then been established, including a 64-gore balloon with geometry based upon Julian Nott's Endeavour. This latter clefted dramatically upon initial inflation, a phenomenon that has been reproduced in the numerical model. Ongoing investigations include the introduction of membrane contact modelling into inTENS and correlation studies with the series of large-scale ULDB models currently in preparation.

  11. Non-linear analysis and the design of Pumpkin Balloons: stress, stability and viscoelasticity

    Science.gov (United States)

    Rand, J. L.; Wakefield, D. S.

    Tensys have a long-established background in the shape generation and load analysis of architectural stressed membrane structures Founded upon their inTENS finite element analysis suite these activities have broadened to encompass lighter than air structures such as aerostats hybrid air-vehicles and stratospheric balloons Winzen Engineering couple many years of practical balloon design and fabrication experience with both academic and practical knowledge of the characterisation of the non-linear viscoelastic response of the polymeric films typically used for high-altitude scientific balloons Both companies have provided consulting services to the NASA Ultra Long Duration Balloon ULDB Program Early implementations of pumpkin balloons have shown problems of geometric instability characterised by improper deployment and these difficulties have been reproduced numerically using inTENS The solution lies in both the shapes of the membrane lobes and also the need to generate a biaxial stress field in order to mobilise in-plane shear stiffness Balloons undergo significant temperature and pressure variations in flight The different thermal characteristics between tendons and film can lead to significant meridional stress Fabrication tolerances can lead to significant local hoop stress concentrations particularly adjacent to the base and apex end fittings The non-linear viscoelastic response of the envelope film acts positively to help dissipate stress concentrations However creep over time may produce lobe geometry variations that may

  12. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage.

    Science.gov (United States)

    Yang, Z; Chen, H; Yu, T; Li, B

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage. PMID:27587158

  13. Thematic outlook: the technical outlook for the fuel cell research network (PACO). December 22, 2003 update no. 19; Veille thematique. La veille technique pour le reseau PACO. Actualisation du 22 decembre 2003, no. 19

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    Summaries of several recent articles and patents are gathered here. They deal with fuel cells, the means of transport, the hydrogen production and with the different new other energies. Their different titles are given below : 1)gas turbine/fuel cell arrangement 2)design and fabrication of a SOFC by CERAMIC FUEL CELLS 3)a 'microbial' fuel cell able of converting glucose in electricity with high yields and velocity 4)a hybrid system: combined cycle gas turbine - multi-stage SOFC 5)a SOFC as auxiliary generator of electricity in an aircraft 6)recent development results of fuel in the Juelich research center 7)state of development of the SOFC at Haldor Topsoe/Risoe 8)a cost/advantage analysis of 'clean cars': methodology and applications to the electric cars 9)the generation of current and heat in a aerostat 10)hydrogen free from CO, produced from bio-ethanol steam reforming on cobalt catalysts supported on ZnO. Effect of the metallic precursor 11)device and method based on the cyclic auto-thermal reforming 12)the ammonia, source of hydrogen for a hybrid system: alkaline fuel/battery 13)effect of the Nafion on the activity of Pt-Ru electrocatalysts for the methanol electro-oxidation 14)'VISION 21': an integration of systems based on coal. The references of these articles and patents are detailed. (O.M.)

  14. Acoustic properties in the low and middle atmospheres of Mars and Venus.

    Science.gov (United States)

    Petculescu, Andi

    2016-08-01

    Generic predictions for acoustic dispersion and absorption in the atmospheres of Mars and Venus are presented. For Mars, Pathfinder and Mars Express ambient data and averaged thermophysical parameters are used as inputs to a preliminary model based on the continuum approximation for Mars' thin atmosphere-the need for Boltzmann-based treatment is discussed in the context of Knudsen numbers. Strong absorption constrains acoustic sensing within the Martian planetary boundary layer. For the dense atmosphere of Venus, the van der Waals equation of state is used. The thermophysical and transport parameters were interpolated at the ambient conditions. Acoustic sensing is discussed at 50 km above Venus' surface, a level where aerostats (e.g., European Space Agency's EVE) and manned airships (e.g., NASA's HAVOC) may be deployed in the future. The salient atmospheric characteristics are described in terms of temperature, pressure, and convective stability profiles, followed by wavenumber predictions, and discussions of low- and high-frequency sensing applications. At low frequencies, emphasis is placed on infrasound. A simple generation mechanism by Martian dust devils is presented, yielding fundamental frequencies between 0.1 and 10 Hz. High-frequency sensing is exemplified by ultrasonic anemometry. Of the two environments, Venus is notably more dispersive in the ultrasonic range. PMID:27586769

  15. LISA: a java API for performing simulations of trajectories for all types of balloons

    Science.gov (United States)

    Conessa, Huguette

    2016-07-01

    LISA (LIbrarie de Simulation pour les Aerostats) is a java API for performing simulations of trajectories for all types of balloons (Zero Pressure Balloons, Pressurized Balloons, Infrared Montgolfier), and for all phases of flight (ascent, ceiling, descent). This library has for goals to establish a reliable repository of Balloons flight physics models, to capitalize developments and control models used in different tools. It is already used for flight physics study software in CNES, to understand and reproduce the behavior of balloons, observed during real flights. It will be used operationally for the ground segment of the STRATEOLE2 mission. It was developed with quality rules of "critical software." It is based on fundamental generic concepts, linking the simulation state variables to interchangeable calculation models. Each LISA model defines how to calculate a consistent set of state variables combining validity checks. To perform a simulation for a type of balloon and a phase of flight, it is necessary to select or create a macro-model that is to say, a consistent set of models to choose from among those offered by LISA, defining the behavior of the environment and the balloon. The purpose of this presentation is to introduce the main concepts of LISA, and the new perspectives offered by this library.

  16. The development of a mathematical model of a hybrid airship

    Science.gov (United States)

    Abdul Ghaffar, Alia Farhana

    The mathematical model of a winged hybrid airship is developed for the analysis of its dynamic stability characteristics. A full nonlinear equation of motion that describes the dynamics of the hybrid airship is determined and for completeness, some of the components in the equations are estimated using the appropriate methods that has been established and used in the past. Adequate assumptions are made in order to apply any relevant computation and estimation methods. While this hybrid airship design is unique, its modeling and stability analysis were done according to the typical procedure of conventional airships and aircrafts. All computations pertaining to the hybrid airship's equation of motion are carried out and any issues related to the integration of the wing to the conventional airship design are discussed in this thesis. The design of the hybrid airship is also slightly modified to suit the demanding requirement of a complete and feasible mathematical model. Then, linearization is performed under a chosen trim condition, and eigenvalue analysis is carried out to determine the general dynamic stability characteristics of the winged hybrid airship. The result shows that the winged hybrid airship possesses dynamic instability in longitudinal pitch motion and lateral-directional slow roll motion. This is due to the strong coupling between the aerostatic lift from the buoyant gas and aerodynamic lift from the wing.

  17. Acoustic properties in the low and middle atmospheres of Mars and Venus.

    Science.gov (United States)

    Petculescu, Andi

    2016-08-01

    Generic predictions for acoustic dispersion and absorption in the atmospheres of Mars and Venus are presented. For Mars, Pathfinder and Mars Express ambient data and averaged thermophysical parameters are used as inputs to a preliminary model based on the continuum approximation for Mars' thin atmosphere-the need for Boltzmann-based treatment is discussed in the context of Knudsen numbers. Strong absorption constrains acoustic sensing within the Martian planetary boundary layer. For the dense atmosphere of Venus, the van der Waals equation of state is used. The thermophysical and transport parameters were interpolated at the ambient conditions. Acoustic sensing is discussed at 50 km above Venus' surface, a level where aerostats (e.g., European Space Agency's EVE) and manned airships (e.g., NASA's HAVOC) may be deployed in the future. The salient atmospheric characteristics are described in terms of temperature, pressure, and convective stability profiles, followed by wavenumber predictions, and discussions of low- and high-frequency sensing applications. At low frequencies, emphasis is placed on infrasound. A simple generation mechanism by Martian dust devils is presented, yielding fundamental frequencies between 0.1 and 10 Hz. High-frequency sensing is exemplified by ultrasonic anemometry. Of the two environments, Venus is notably more dispersive in the ultrasonic range.

  18. Modeling and Simulation Tools for Heavy Lift Airships

    Science.gov (United States)

    Hochstetler, Ron; Chachad, Girish; Hardy, Gordon; Blanken, Matthew; Melton, John

    2016-01-01

    For conventional fixed wing and rotary wing aircraft a variety of modeling and simulation tools have been developed to provide designers the means to thoroughly investigate proposed designs and operational concepts. However, lighter-than-air (LTA) airships, hybrid air vehicles, and aerostats have some important aspects that are different from heavier-than-air (HTA) vehicles. In order to account for these differences, modifications are required to the standard design tools to fully characterize the LTA vehicle design and performance parameters.. To address these LTA design and operational factors, LTA development organizations have created unique proprietary modeling tools, often at their own expense. An expansion of this limited LTA tool set could be accomplished by leveraging existing modeling and simulation capabilities available in the National laboratories and public research centers. Development of an expanded set of publicly available LTA modeling and simulation tools for LTA developers would mitigate the reliance on proprietary LTA design tools in use today. A set of well researched, open source, high fidelity LTA design modeling and simulation tools would advance LTA vehicle development and also provide the analytical basis for accurate LTA operational cost assessments. This paper will present the modeling and analysis tool capabilities required for LTA vehicle design, analysis of operations, and full life-cycle support. A survey of the tools currently available will be assessed to identify the gaps between their capabilities and the LTA industry's needs. Options for development of new modeling and analysis capabilities to supplement contemporary tools will also be presented.

  19. Software for Correcting the Dynamic Error of Force Transducers

    Directory of Open Access Journals (Sweden)

    Naoki Miyashita

    2014-07-01

    Full Text Available Software which corrects the dynamic error of force transducers in impact force measurements using their own output signal has been developed. The software corrects the output waveform of the transducers using the output waveform itself, estimates its uncertainty and displays the results. In the experiment, the dynamic error of three transducers of the same model are evaluated using the Levitation Mass Method (LMM, in which the impact forces applied to the transducers are accurately determined as the inertial force of the moving part of the aerostatic linear bearing. The parameters for correcting the dynamic error are determined from the results of one set of impact measurements of one transducer. Then, the validity of the obtained parameters is evaluated using the results of the other sets of measurements of all the three transducers. The uncertainties in the uncorrected force and those in the corrected force are also estimated. If manufacturers determine the correction parameters for each model using the proposed method, and provide the software with the parameters corresponding to each model, then users can obtain the waveform corrected against dynamic error and its uncertainty. The present status and the future prospects of the developed software are discussed in this paper.

  20. A high-precision instrument for analyzing nonlinear dynamic behavior of bearing cage

    Science.gov (United States)

    Yang, Z.; Chen, H.; Yu, T.; Li, B.

    2016-08-01

    The high-precision ball bearing is fundamental to the performance of complex mechanical systems. As the speed increases, the cage behavior becomes a key factor in influencing the bearing performance, especially life and reliability. This paper develops a high-precision instrument for analyzing nonlinear dynamic behavior of the bearing cage. The trajectory of the rotational center and non-repetitive run-out (NRRO) of the cage are used to evaluate the instability of cage motion. This instrument applied an aerostatic spindle to support and spin test the bearing to decrease the influence of system error. Then, a high-speed camera is used to capture images when the bearing works at high speeds. A 3D trajectory tracking software tema Motion is used to track the spot which marked the cage surface. Finally, by developing the matlab program, a Lissajous' figure was used to evaluate the nonlinear dynamic behavior of the cage with different speeds. The trajectory of rotational center and NRRO of the cage with various speeds are analyzed. The results can be used to predict the initial failure and optimize cage structural parameters. In addition, the repeatability precision of instrument is also validated. In the future, the motorized spindle will be applied to increase testing speed and image processing algorithms will be developed to analyze the trajectory of the cage.

  1. In-situ exploration of Venus on a global scale : direct measurements of origins and evolution, meterology, dynamics, and chemistry by a long-duration aerial science station

    Science.gov (United States)

    Baines, Kevin H.; Atreya, Sushi; Carlson, Robert W.; Chutjian, Ara; Crisp, David; Hall, Jeffrey L.; Jones, Dayton L.; Kerzhanovich, Victor V.; Limaye, Sanjay S.

    2005-01-01

    Drifting in the strong winds of Venus under benign Earth-like temperature and pressure conditions, an instrumented balloon-borne science station presents a viable means to explore, in-situ, the Venusian atmosphere on a global scale. Flying over the ground at speeds exceeding 240 km/hour while floating in the Venusian skies near 55 km altitude for several weeks, such an aerostat can conduct a 'world tour' of our neighboring planet, as it circumnavigates the globe multiple times during its flight from equatorial to polar latitudes. Onboard science sensors can repeatedly and directly sample gas compositions, atmospheric pressures and temperatures and cloud particle properties, giving unprecedented insight into the chemical processes occurring within the sulfuric clouds. Additionally, interferometric tracking via Earth-based radio observatories can yield positions and windspeeds to better than 10 cm/sec over one-hour periods, providing important information for understanding the planet's meridional circulation and enigmatic zonal super-rotation, as well as local dynamics associated with meteorological processes. As well, hundreds of GCMS spectra collected during the flight can provide measurements of noble gas compositions and their isotopes with unprecedented accuracy, thereby enabling fundamental new insights into Venus's origin and evolution.

  2. External laser locking using a pressure-tunable microbubble resonator

    CERN Document Server

    Madugani, Ramgopal; Le, Vu H; Ward, Jonathan M; Chormaic, Síle Nic

    2015-01-01

    The tunability of an optical cavity is an essential requirement for many areas of research especially for the rapidly progressing field of photonics. In particular, low-cost laser tuning methods and miniaturization of the optical components are desirable. By applying aerostatic pressure to the interior surface of a microbubble resonator, optical mode shift rates of around $58$ GHz/MPa are achieved. The micobubble can measure pressure with a limit of detection of $2\\times 10^{-4}$ MPa. Here we use the Pound-Drever-Hall technique, whereby a laser is locked to a whispering gallery mode (WGM) of the microbubble resonator, to show that linear tuning of the WGM and the corresponding locked laser display almost zero hysteresis. The long-term frequency stability of this tuning method for different input pressures is measured. The frequency noise of the WGM, measured over 10 minutes, with a maximum input pressure of 0.5 MPa has a standard deviation of 36 MHz.

  3. A method for establishing a long duration, stratospheric platform for astronomical research

    Science.gov (United States)

    Fesen, Robert; Brown, Yorke

    2015-10-01

    During certain times of the year at middle and low latitudes, winds in the upper stratosphere move in nearly the opposite direction than the wind in the lower stratosphere. Here we present a method for maintaining a high-altitude balloon platform in near station-keeping mode that utilizes this stratospheric wind shear. The proposed method places a balloon-borne science platform high in the stratosphere connected by a lightweight, high-strength tether to a tug vehicle located in the lower or middle stratosphere. Using aerodynamic control surfaces, wind-induced aerodynamic forces on the tug can be manipulated to counter the wind drag acting on the higher altitude science vehicle, thus controlling the upper vehicle's geographic location. We describe the general framework of this station-keeping method, some important properties required for the upper stratospheric science payload and lower tug platforms, and compare this station-keeping approach with the capabilities of a high altitude airship and conventional tethered aerostat approaches. We conclude by discussing the advantages of such a platform for a variety of missions with emphasis on astrophysical research.

  4. Calibration of non-contact incremental linear encoders using a macro–micro dual-drive high-precision comparator

    International Nuclear Information System (INIS)

    The accuracy of a linear encoder is determined by encoder-specific errors, which consist of both long-range and cyclic errors. Generally, it is difficult to measure the two errors of a non-contact incremental linear encoder with a large measuring range and small signal period in one measurement because of the contradiction between long travel range and high resolution. To resolve this issue, a prototype high-precision interferometric comparator with a macro–micro dual-drive system is presented. The measurement and motion resolution of the comparator are 1 nm and 3 nm, respectively. A measuring range of 320 mm is realized and the theoretical maximum range of the comparator is 2 m. The comparator mainly includes a high-accuracy aerostatic linear-motion stage, a constant displacement ratio piezoelectric-driven stage, two laser interferometers, a 6-DOF grating pair position adjustment devices and a PC-based data processor. The measurable linear movement is afforded, respectively, by the long-stroke stage and the piezoelectric-driven stage for the long-range error and cyclic error measurement. The movement can be measured by the encoder and then be calibrated by the corresponding laser interferometer. In the experiment, the accuracy of a non-contact incremental linear encoder with a 20 μm-long signal period and 320 mm measuring range proposed by our team was calibrated after proper mounting. The long-range error is measured to be 3.123 μm, and the cyclic error is within  ±0.159 μm, which matches well with the theoretical estimation given by  ±0.145 μm. The measurement uncertainties are estimated and the results confirm the effectiveness and feasibility of the proposed scheme and instruments. (paper)

  5. Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element bearing

    International Nuclear Information System (INIS)

    The rotational performance of high-precision rolling bearings is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision bearings of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test bearing. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-bearing subjected to non-contact and precise loaded axial forces. The measurement results on axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test bearing which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the bearing at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements’ repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings

  6. Lifting options for stratospheric aerosol geoengineering: advantages of tethered balloon systems.

    Science.gov (United States)

    Davidson, Peter; Burgoyne, Chris; Hunt, Hugh; Causier, Matt

    2012-09-13

    The Royal Society report 'Geoengineering the Climate' identified solar radiation management using albedo-enhancing aerosols injected into the stratosphere as the most affordable and effective option for geoengineering, but did not consider in any detail the options for delivery. This paper provides outline engineering analyses of the options, both for batch-delivery processes, following up on previous work for artillery shells, missiles, aircraft and free-flying balloons, as well as a more lengthy analysis of continuous-delivery systems that require a pipe connected to the ground and supported at a height of 20 km, either by a tower or by a tethered balloon. Towers are shown not to be practical, but a tethered balloon delivery system, with high-pressure pumping, appears to have much lower operating and capital costs than all other delivery options. Instead of transporting sulphuric acid mist precursors, such a system could also be used to transport slurries of high refractive index particles such as coated titanium dioxide. The use of such particles would allow useful experiments on opacity, coagulation and atmospheric chemistry at modest rates so as not to perturb regional or global climatic conditions, thus reducing scale-up risks. Criteria for particle choice are discussed, including the need to minimize or prevent ozone destruction. The paper estimates the time scales and relatively modest costs required if a tethered balloon system were to be introduced in a measured way with testing and development work proceeding over three decades, rather than in an emergency. The manufacture of a tether capable of sustaining the high tensions and internal pressures needed, as well as strong winds, is a significant challenge, as is the development of the necessary pumping and dispersion technologies. The greatest challenge may be the manufacture and launch of very large balloons, but means have been identified to significantly reduce the size of such balloons or aerostats.

  7. The Measurement of Nine Inertial Parameters of Rigid Body Based on the Moment of Inertia%基于转动惯量的刚体9个惯性参数的测量

    Institute of Scientific and Technical Information of China (English)

    王瑾; 孙宁

    2012-01-01

    针对三维空间,提出了一种可以同时测量刚体9个惯性参数的新方法.利用气体静压轴承低速自由转动时其角速度是一个随时间衰减的单指数函数这一运动规律,测量物体绕任意的转动惯量,通过9次测量最终求出刚体的9个惯性参数.设计了一套物体惯性参数测量仪,该测量仪可以同时测量三维空间中物体的9个惯性参数.测量过程中无需重新装配,减少了中间测试量及人为干预误差,使测量时间缩短,测量精度提高.%For three-dimensional space, a new method which can measure the nine inertial parameters of a rigid body simultaneously is proposed. With the law of motion that when aerostatic bearing move slowly its angular velocity is a single exponential function decayed with time, the moment of inertia of the rigid body rotating a axis in an arbitrary direction is obtained, through nine measurements, the inertial parameters of a rigid body can be got finally. A set of instrument used for measuring the rigid body inertial parameters is designed. This instrument can measure the nine inertial parameters of a rigid body in three-dimensional space simultaneously. There' s no need to re-assembly in the process of measurement, so intermediate testing quantity, error made by human and measuring time are all reduced.

  8. Middle atmospheric electric fields over thunderstorms

    Science.gov (United States)

    Holzworth, Robert H.

    1992-01-01

    This grant has supported a variety of investigations all having to do with the external electrodynamics of thunderstorms. The grant was a continuation of work begun while the PI was at the Aerospace Corporation (under NASA Grant NAS6-3109) and the general line of investigation continues today under NASA Grants NAG5-685 and NAG6-111. This report will briefly identify the subject areas of the research and associated results. The period actually covered by the grant NAG5-604 included the following analysis and flights: (1) analysis of five successful balloon flights in 1980 and 1981 (under the predecessor NASA grant) in the stratosphere over thunderstorms; (2) development and flight of the Hy-wire tethered balloon system for direct measurement of the atmospheric potential to 250 kV (this involved multiple tethered balloon flight periods from 1981 through 1986 from several locations including Wallops Island, VA, Poker Flat and Ft. Greely, AK and Holloman AFB, NM.); (3) balloon flights in the stratosphere over thunderstorms to measure vector electric fields and associated parameters in 1986 (2 flights), 1987 (4 flights), and 1988 (2 flights); and (4) rocket-borne optical lightning flash detectors on two rocket flights (1987 and 1988) (the same detector design that was used for the balloon flights listed under #3). In summary this grant supported 8 stratospheric zero-pressure balloon flights, tethered aerostat flights every year between 1982-1985, instruments on 2 rockets, and analysis of data from 6 stratospheric flights in 1980/81.

  9. 旋转冲压发动机高速动静混合气体轴承性能分析%Performance analysis of high-speed hybrid gas bearings for rotating ramjet

    Institute of Scientific and Technical Information of China (English)

    张广辉; 刘占生

    2009-01-01

    The performance of high-speed hybrid gas bearings for rotating ramjet was studied theoretically and numerically to fulfill the requirement of bearing support for rotating ramjet.The gas supply pressure was determined firstly by the work condition of the rotating ramjet.By employing the Newton method and finite difference method,the Reynolds equations for the gas flow in the bearings were solved.The pressure distributions of the hybrid bearings with different eccentricities and rotating speed were obtained and the coupling mechanics of aerostatic and aerodynamic was analyzed.And also the number of orifices sets,which has effect on the pressure distribution and load capacity,was discussed.The maximum rotor weights for different rotating speeds and orifices set numbers,which the hybrid gas bearings could provide,were listed to establish the foundation for the design of rotating ramjet rotor system.%为了满足旋转冲压发动机对高速支撑的要求,本文对动静压混合高速气体轴承进行理论分析与数值研究.首先通过旋转冲压发动机的工作条件确定了气体轴承的供气压力,对描述轴承内气体流动的雷诺方程采用牛顿迭代与有限差分法进行求解,获得不同偏心、不同转速下轴承内气体压力分布并分析动静压耦合机理.同时分析了不同供气孔排数对压力分布与承载能力的影响,给出了不同转速、不同供气孔排数下轴承所能支撑的最大转子重量,为下一步旋转冲压发动机转子系统设计奠定基础.

  10. Biotic pump of atmospheric moisture as driver of the hydrological cycle on land

    Directory of Open Access Journals (Sweden)

    A. M. Makarieva

    2007-01-01

    Full Text Available In this paper the basic geophysical and ecological principles are jointly analyzed that allow the landmasses of Earth to remain moistened sufficiently for terrestrial life to be possible. 1. Under gravity, land inevitably loses water to the ocean. To keep land moistened, the gravitational water runoff must be continuously compensated by the atmospheric ocean-to-land moisture transport. Using data for five terrestrial transects of the International Geosphere Biosphere Program we show that the mean distance to which air fluxes can transport moisture over non-forested areas, does not exceed several hundred kilometers; precipitation decreases exponentially with distance from the ocean. 2. In contrast, precipitation over extensive natural forests does not depend on the distance from the ocean along several thousand kilometers, as illustrated for the Amazon and Yenisey river basins and Equatorial Africa. This points to the existence of an active biotic pump transporting atmospheric moisture inland from the ocean. 3. Physical principles of the biotic moisture pump are investigated based on the previously unstudied properties of atmospheric water vapor, which can be either in or out of aerostatic equilibrium depending on the lapse rate of air temperature. A novel physical principle is formulated according to which the low-level air moves from areas with weak evaporation to areas with more intensive evaporation. Due to the high leaf area index, natural forests maintain high evaporation fluxes, which support the ascending air motion over the forest and "suck in" moist air from the ocean, which is the essence of the biotic pump of atmospheric moisture. In the result, the gravitational runoff water losses from the optimally moistened forest soil can be fully compensated by the biotically enhanced precipitation at any distance from the ocean. 4. It is discussed how a continent-scale biotic water pump mechanism could be produced by natural selection acting on

  11. 双斜塔钢箱梁斜拉桥抗风性能试验研究%Experimental investigation on wind-resistant behavior of double pylon cable stayed bridge with steel box beam

    Institute of Scientific and Technical Information of China (English)

    马存明; 陈勉; 王玉柱; 高伟

    2011-01-01

    In order to evaluate wind-resistant behavior of a double pylon cable stayed bridge with steel box beam, dynamic response characteristics of the bridge were analyzed. The aerostatic force coefficient, the critical wind velocity of vibration and vortex-induced vibration response were measured using the combined method of numerical analysis and wind tunnel test, to assess wind-resistant behavior of the bridge. The results showed that the aerodynamic and flutter stability characteristics were good, but there were two obvious vertical vortex-induced resonance regions, and the peak excursion was much larger than the allowable value. Therefore, the bridge needs an aerodynamic shape optimization to reduce or control vortex-induced vibration. By comparing a variety of optimization solutions given by vortex-induced vibration experiments, the most optimized measure for vortex-induced vibration control was to add a fair water fin of 1m wide and 30° incline to the bottom slab.%为了评价某拟建大跨度双斜塔钢箱梁斜拉桥的抗风安全性能,通过数值分析与风洞试验相结合的方法研究其结构动力特性,测定静力三分力系数、颤振临界风速和涡激振动响应,据此分析评估该桥的抗风性能.结果表明,该桥具有较好的气动和颤振稳定性,但存在两个明显的竖向涡激共振区,且最大振幅远超过规定容许值.因此,该桥需要通过气动外形优化,以减小或控制涡激振动.经多种主梁涡激振动性能优化方案对比试验得出其最优措施为轨道内侧增加一条宽1m、与底板夹角成30°的导流板.

  12. Sights from the air

    Science.gov (United States)

    Tartara, P.

    2009-04-01

    The first aerial shots were taken by aerostat balloon during the second half of the nineteen century for military purpose and subsequently utilized for civilian, archaeological and town planning uses (Roman Forum 1900, Pompei 1910, Venezia 1913, etc.). Sights from the air have given the most objective representation of the landscape and traces progressively left by human activities. After the First World War the use of airplanes for photogrammetric shots suitable to create cartography (territorial map making) has permitted to realize a good basic documentation; successively it has been increased by aerial reconnaissance during the Second World War. Aerial shots by RAF, USAF and Luftwaffe brought to the establishment of rich aerial photograph Archives, particularly in Europe, which have had a very low utilization for the historical restoration of landscape. From the fifties, aerial documentation becomes systematic for different scale analysis and territorial planning. The use of satellite imagery and multispectral bands integrates the historical and recent aerial photographs; the former is particularly helpful for cartography updating, for large scale environmental analysis, for study and research of territories with not available air photographs or lacking in aerial shots. The amount and density of archaeological buried evidences, unknown at the most, is very substantial in Italy and in the whole Mediterranean area; here air-photo interpretation is being applied at advanced levels, but not systematically, since several decades. Some archaeological research teams, working for the knowledge of territorial cultural heritage, utilize historical and recent aerial photographs intensively (aerial photographs previous the II WW, just before the intensive and extensive use of mechanical means to till the land, preserve a large amount of traces or cropmarks of buried evidences; recent shots taken on different conditions of climate and crops, allow to see and read important

  13. Design of measuring machine for complex geometry based on form-free measurement mode%基于免形状测量模式的复杂形状测量机设计

    Institute of Scientific and Technical Information of China (English)

    石照耀; 张斌; 林家春

    2012-01-01

    To measure complex geometries without nominal mathematics models, a "form-free measurement mode" is introduced, and its basic requirements for measuring machine are analyzed. A fixed column structure coordinate measuring machine with high accuracy and efficiency was designed based on the novel mode. The machine is driven by linear motors, and high accuracy gratings are used as measurement devices. To decrease the influence of work-piece weight, a closed aerostatic bearing with vacuum preload and an H style two dimensional co-planar structure are designed. A pneumatic cylinder balanced axis Z assembly with brake function is designed, and a vibration isolation assembly is also designed. The measurement span of the machine is 300 mm × 300 mm × 300 mm and the measurement uncertainty is 1.8 μm. It can be applied to measure complex geometries without nominal mathematics models.%为了高精度高效率地测量数学模型未知的复杂几何形状,介绍了“免形状测量模式”,分析了该测量模式对仪器的基本要求,基于该模式设计了一台移动工作台式测量机.测量机以直线电机为驱动元件,以高精度长光栅为测量元件.为减小被测件重量对测量机的影响,设计了封闭式真空负压的空气静压气浮导轨和共平面的H形二维结构.设计了具有制动功能的Z轴和气浮隔振等关键部件.仪器量程为300 mm × 300 mm×300 mm,测量不确定度为1.8μm,能测量数学模型未知的复杂几何形状.

  14. Coherent Uncertainty Analysis of Aerosol Measurements from Multiple Satellite Sensors

    Science.gov (United States)

    Petrenko, M.; Ichoku, C.

    2013-01-01

    Aerosol retrievals from multiple spaceborne sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS altogether, a total of 11 different aerosol products were comparatively analyzed using data collocated with ground-based aerosol observations from the Aerosol Robotic Network (AERONET) stations within the Multi-sensor Aerosol Products Sampling System (MAPSS, http://giovanni.gsfc.nasa.gov/mapss/ and http://giovanni.gsfc.nasa.gov/aerostat/). The analysis was performed by comparing quality-screened satellite aerosol optical depth or thickness (AOD or AOT) retrievals during 2006-2010 to available collocated AERONET measurements globally, regionally, and seasonally, and deriving a number of statistical measures of accuracy. We used a robust statistical approach to detect and remove possible outliers in the collocated data that can bias the results of the analysis. Overall, the proportion of outliers in each of the quality-screened AOD products was within 12%. Squared correlation coefficient (R2) values of the satellite AOD retrievals relative to AERONET exceeded 0.6, with R2 for most of the products exceeding 0.7 over land and 0.8 over ocean. Root mean square error (RMSE) values for most of the AOD products were within 0.15 over land and 0.09 over ocean. We have been able to generate global maps showing regions where the different products present advantages over the others, as well as the relative performance of each product over different landcover types. It was observed that while MODIS, MISR, and SeaWiFS provide accurate retrievals over most of the landcover types, multi-angle capabilities make MISR the only sensor to retrieve reliable AOD over barren and snow / ice surfaces. Likewise, active sensing enables CALIOP to retrieve aerosol properties over bright-surface shrublands more accurately than the other sensors, while POLDER, which is the only one of the sensors capable of measuring polarized aerosols, outperforms other sensors in

  15. The Effectiveness of an Evaluation Model Based on Evidential Reasoning and its Application in the Planning of Multiple Missions in the Near Space%基于证据推理的效能评估及其在临近空间多任务规划中的应用

    Institute of Scientific and Technical Information of China (English)

    彭张林; 濮剑鹏; 张登洲; 胡笑旋; 张强; 詹明明

    2013-01-01

    As military and commercial values of near space exploration increase, air vehicles ( e. g. hypersonic vehicles and aerostats) installed in the near space are carrying more responsibility for military missions. Near space systems may have multiple military missions at the same time, and demand multi-mission planning. In the multi-mission planning, multiple alternatives may exist in order to meet the mission demand and resource attributes. However, what is the best planning alternative? This paper intends to evaluate the effectiveness of near space systems under different planning situations and decide on a multi-mission planning solution to maximize or optimize the effectiveness of near space system evaluation. One central problem of this study is to evaluate the effectiveness of near apace systems. Near space systems involve dynamic variables, such as multiple resources, multiple missions, complex internal and external conditions. Therefore, traditional assessment methods will face the problem of evaluating the effectiveness of the coexistence of various certainties and uncertainties because they often deal with each variable independently. Evidential reasoning method considers various kinds of uncertainties, such as ignorance, fuzziness, interval data, and interval belief degrees, and can implement multiple sources of evidence. As such, the method can overcome the limitation of uncertain evaluations. In contrast, the traditional method deals with complex conditions and can effectively solve problems associated with the effectiveness evaluation of near space system to perform multiple missions. In view of this, this paper constructs an effectiveness evaluation model based on the evidential reasoning method, and applies the model in planning for performing multiple missions in the near space system. This paper is composed of two parts as follows: Firstly, this paper constructs an effectiveness evaluation model based on the evidential reasoning theory. This model is

  16. Unmanned Airborne Platforms for Validation of Volcanic Emission Composition and Transport Models

    Science.gov (United States)

    Pieri, D. C.; Diaz, J. A.; Bland, G.; Fladeland, M. M.

    2012-12-01

    satellite remote sensing data remain systematically unvalidated by in situ data. Of special concern with respect to aircraft operations are the validity syn-and-post eruption of estimates of the lateral and vertical extent, concentrations, and spatio-temporal variability of drifting volcanic ash clouds provided by aerosol transport models and remote sensing techniques. Within NASA there exist a variety of novel technological approaches for conducting in situ validation experiments, particularly the use of specially designed unmanned aircraft and miniaturized (e.g., mass spectrometers, optical particle detectors, impact samplers) instrumentation to range through ash and gas clouds, and the deployment of instrumented tethered aerostats up into such clouds, in coordination with multispectral satellite, airborne, and ground-based observations. For instance, new more powerful electric-powered UAVs may be most appropriate for these very hazardous regimes. A brief review of scientific issues and operational practices will be presented, along with a case study of our work at Turrialba Volcano in Costa Rica. This work was carried out in part at the Jet Propulsion Laboratory of the California Institute of Technology under contract to NASA.

  17. Device development for radioecology monitoring in Azerbaijan Republic

    International Nuclear Information System (INIS)

    Last time in the territory of Azerbaijan Republic that's in the land and especially in Azerbaijan sector of Caspian Sea have observed the irreversible processes as result of anthropogenic influences to the environment. In the main these inclinations envelope following from signed oil contracts the boring works for prospecting and production, building works on the oil pipelines and increase of quantity of the wastes created by these kinds of an activity. But at the land these inclinations envelope the revealing of radioactive materials at not controlled sectors of military bases leave in inheritance by former Soviet Union. At the same time have observed sharp increase of the transit load transporting power on the 'Silk way' route restored within the frames of TRACEKA. And that, in its turn, demand the organization of corresponding control of these loads. For organization of above-mentioned works have proposed next devices and equipment: The device DRG-01Az designed for an exposure dose power measurements of gamma radiations. Air gamma spectrometer. Managed from scientific-research craft the gamma spectrometer for gamma removals of seabed. Stationary radiation post for continuous control of the transit trucks. Proposed devices have worked out by the group of Special Space Device Development Bureau of Azerbaijan National Aerospace Agency. It should be noted that this group had important achievements at the sphere of space device development still since 70-th years. So in 1981 within the frames of the Soviet-French combined experiment was make a multi-channel gamma spectrometer mounted on the aerostat flied on the large heights (30-40 km). In 1983 was work out an orbital device 'RS-17' located at the satellite 'Cosmos-1638'. In 1987 was make a gamma telescope 'Pulsar X-1' established on the orbital station 'Mir'. A telescope is working successfully till now. Above-mentioned devices establish on the basis of obtained achievements. For example, the constructional demands

  18. after tomorrow

    Directory of Open Access Journals (Sweden)

    Elena Grigoryeva

    2011-05-01

    Full Text Available It is ridiculous to make plans in this world, especially when Bulgakov’s Annushka has already spilled the oil. The convulsion of nature in the neighbouring Japan confirms this once again. The destiny of Japan in general and of the UIA Tokyo Congress in particular is of great concern, as well as the courageous behaviour of the whole nation in the face of Mother Nature’s devastating anger. Actually, the subject of this issue – a long-term prognosis – was suggested by the themes of the UIA Congress “Design 2050” and of the next Winter University Session “Irkutsk 2036”.If you want to make God laugh, tell Him your plans. However, the essence of our profession is creation of environment for future life. So we cannot do without long-term prognoses. An architect works for the future, but there are many futures. There are a number of trajectories of further development starting from the point of today. Every scenario leads to its own future, and the architect is to choose the future with maximum realization chances, to reveal and to study several vectors of possible course of events and to choose the most harmonious among the realistic ones.Sometimes an architect’s imagination pictures a future that seems to other people absolutely impossible. There are times when this very scenario, quite unexpectedly for skeptics, becomes realized and makes others believe in it. Nobel laureates say that levitation is beyond doubt, and any time a human body can rise above the ground. Obviously, the cities will look quite different in this case, if they remain at all. But aerostatic architecture has already got adherents with concrete proposals (36The science of future development appeared more than one hundred years ago. Today its first experiments look childishly naïve. The day before yesterday’s fantasies of cities in the early 2000s evoke a gracious smile more often than admiration for their precise