Search

Station-keeping endurance of high altitude balloon is the foundation of the assignments of environmental monitoring and communicational relaying. Exploiting the natural wind-field that varies with altitude by the altitude control system to extend the station-keeping endurance is proposed in this paper. A Matlab program is developed based on the theoretical model to simulate the station-keeping performance of the balloon in the real wind field. The trajectories of the balloon in different wind fields and the states of the balloon caused by the venting and pumping processes are discussed in detail. The results show that with the altitude control system it is possible to retain the balloon within the designated district for few days to a week. This can serve as a guideline for the design and initial flight tests of the serviceable high altitude balloon. [ABSTRACT FROM AUTHOR]

Super-pressure balloons are closed structures with periodical gores and are more stable than the traditional zero-pressure balloons. They are regarded as aerostats which can stay in the high altitude for a long time. A steady-state analysis model is created to simulate the membrane stress and displacement affected by the inner pressure, and then the hot spot, cold spot, and temperature fields of the super-pressure balloon are analyzed in the stratospheric environment at different times. Besides the different periodical gores, inner pressure and temperature effect on the strain and displacement of the balloon are also discussed. Moreover, the thermodynamic properties of the super-pressure balloons are analyzed, according to the solar radiation, the surface radiation, the sunlight reflection, and self-infrared radiation features, as well as the heat convection of the surrounding atmosphere. Finally, these thermodynamic properties are given at three particular moments. These results can provide the references for the design of super-pressure balloons with periodical gores. [ABSTRACT FROM AUTHOR]

On October 5 2011 saw a unique experiment took place in Romania, which involved the successfully launching a high altitude balloon on the border between the atmosphere and outer space, setting a new record for Eastern Europe: 35 304 m and taking the first photos of the Danube Delta and the Black Sea in the stratosphere . This paper presents the people behind this event. In this mission, was made an interesting documentary with spectacular images made the day of release, both on the ground - the preparation and the actual launch and in space, the camera mounted in the balloon basket, which showed what Romania looks like seen from the space. [ABSTRACT FROM AUTHOR]

The present paper examines the vortex breakdown and large-scale stirring during the final warming of the Southern Hemisphere stratosphere during the spring of 2005. A unique set of in situ observations collected by 27 superpressure balloons (SPBs) is used. The balloons, which were launched from McMurdo, Antarctica, by the Stratéole/VORCORE project, drifted for several weeks on two different isopycnic levels in the lower stratosphere. We describe balloon trajectories and compare them with simulations obtained on the basis of the velocity field from the GEOS-5 and NCEP/NCAR reanalyses performed with and without VORCORE data. To gain insight on the mechanisms responsible for the horizontal transport of air inside and outside the well-isolated vortex we examine the balloon trajectories in the framework of the Lagrangian properties of the stratospheric flow. Coherent structures of the flow are visualized by computing finite-time Lyapunov exponents (FTLE). A combination of isentropic analysis and FTLE distributions reveals that air is stripped away from the vortex's interior as stable manifolds eventually cross the vortex's edge. It is shown that two SPBs escaped from the vortex within high potential vorticity tongues that developed in association with wave breaking at locations along the vortex's edge where forward and backward FTLE maxima approximately intersect. The trajectories of three SPBs flying as a group at the same isopycnic level are examined and their behavior is interpreted in reference to the FTLE field. These results support the concept of stable and unstable manifolds governing transport of air masses across the periphery of the stratospheric polar vortex. [ABSTRACT FROM AUTHOR]

The Titan Saturn System Mission (TSSM) concept is composed of a TSSM orbiter provided by NASA that would carry two Titan in situ elements provided by ESA: the montgolfière and the probe/lake lander. One overarching goal of TSSM is to explore in situ the atmosphere and surface of Titan. The mission has been prioritized as the second Outer Planets Flagship Mission, the first one being the Europa Jupiter System Mission (EJSM). TSSM would launch around 2023–2025 arriving at Saturn 9 years later followed by a 4-year science mission in the Saturn system. Following delivery of the in situ elements to Titan, the TSSM orbiter would explore the Saturn system via a 2-year tour that includes Enceladus and Titan flybys before entering into a dedicated orbit around Titan. The Titan montgolfière aerial vehicle under consideration will circumnavigate Titan at a latitude of ~20° and at altitudes of ~10 km for a minimum of 6 months. The probe/lake lander will descend through Titan’s atmosphere and land on the liquid surface of Kraken Mare (~75° north latitude). As for any planetary space science mission, and based on the Cassini–Huygens experience, Earth-based observations will be synergistic and enable scientific optimization of the return of such a mission. Some specific examples of how this can be achieved (through VLBI and Doppler tracking, continuous monitoring of atmospheric and surface features, and Direct-to-Earth transmission) are described in this paper. [ABSTRACT FROM AUTHOR]

In this paper, we establish rigorous existence theorems for a mathematical model of a tendon-reinforced thin wrinkled membrane that is subjected to a shape dependent hydrostatic pressure load. We are motivated by the problem of determining the equilibrium shape of a strained high altitude large scientific balloon. This problem has a number of unique features. The balloon is very thin (20-40 nm), especially when compared with its diameter (over 100 meters). The balloon is unable to support compressive stresses and, instead, wrinkles or forms folds of excess material. Our approach can be adapted to a wide variety of inflatable structures, but we will focus on two types of high altitude balloons, a zero-pressure natural shape balloon and a super-pressure pumpkin-shaped balloon, We outline the shape finding process for these two classes of balloon designs, formulate the problem of a strained balloon in an appropriate Sobolev space setting, establish rigorous existence theorems using direct methods in the calculus of variations, and present numerical studies to complement our theoretical results. [ABSTRACT FROM AUTHOR]

The history of lighter-than-air operations in the Arctic between 1896 and 1930 has focused almost exclusively upon four expeditions. These are the balloon voyage of the Swede Salomon Andrée in 1896–97, and the dirigible expeditions of the American Walter Wellman in 1906–09, the Norwegian Roald Amundsen with the Italian Umberto Nobile in 1926 and the Nobile expedition of 1928. Largely invisible in this lineage are the aeronautical operations of the Baldwin–Ziegler Polar Expedition on Alger Island in the Franz Josef Land Archipelago in 1902. This article traces expedition leader Evelyn Briggs Baldwin's interest in aeronautical exploration in the Arctic, which began early in life, led to a failed attempt to join Andrée in 1897 and culminated in his use of message buoys attached to balloons in June 1902. These operations, the fate of its balloon buoys and the historical archaeology of Baldwin's operational bases in Franz Josef Land and north-east Greenland are examined. Baldwin's poor planning and bad luck with ice conditions around Franz Josef Land caused him to use his balloon buoys not to reach northwards to the pole, but to send relief messages southwards towards civilization. Like the other polar aeronautical expeditions, Baldwin's left behind a significant archaeological assemblage that continues to provide evidence for the material analysis of the history of polar exploration. [ABSTRACT FROM AUTHOR]

This paper presents a survey of the Tethered Lifting System (TLS) being developed for atmospheric research by the Cooperative Institute for Research in Environmental Sciences (CIRES) at University of Colorado. Basic elements of the system are described, and examples of both published results and work in progress are presented. [ABSTRACT FROM AUTHOR]

The assessment of creep and dynamic response behaviors on materials intended for ultra long duration balloon (ULDB) applications is essential. The first provides needed information for design and fabrication. The second ensures that the film is sufficiently tough to survive the dynamic events during launch and ascent. Characterization and assessment of these two important parameters are discussed in this paper. Visco-elastic behavior of materials in a loaded structure, such as the ULDB film change their geometry significantly over time under load causing possible changes in the load path and the stress distribution. These changes must be held in check to satisfy the functional requirements of the structure over its service life. Typically, the balloon experiences during its service life various environmental conditions each with a different creep response. These are characterized by a simplified load temperature history for the purpose of lifetime response assessment. At mid-latitudes a significant portion of the service life is spent at night, i.e., at low temperature and low load; for the ULDB film this night-time contribution to creep is negligible. By contrast, flight exposure in an Antarctic summer is at an almost constant high temperature and corresponding high pressure. This paper presents the creep behavior of the ULDB film as a function of load, temperature, and time along with an overview of its implementation in the design. In addition, it presents a quantitative assessment on the toughness of the material under dynamic “Snatch” loading. [Copyright &y& Elsevier]

Cohen and Cohen''s balloon model improves the original active contour models by providing an ability to search for distant contours. Driven by an artificial inflating force, a balloon''s searching ability is rather primitive. In previous papers, we have presented several new models that incorporate different cues in their searching algorithm. In this paper, we present a new method that uses local image contents to guide a balloon''s searching process. Sha''ashua and Ullman''s saliency map method is used to trace the strongest curve that passes through a particular pixel. This locally-derived information is then used to guide a balloon''s searching process. Benefiting from both a global model and locally derived cues, the combined model is faster and more robust than the original balloon model. [Copyright &y& Elsevier]

Objectives: Health-care providers are expected to deliver quality patient care cost-effectively, especially in developing countries. Medical devices labeled "single use only" should ideally not be reused but, can be considered for reuse due to their higher cost. Stringently regulated reprocessing of the single-use device provides an opportunity to do so along with the potential to have a favorable impact on environmental waste. The aim of this study is to assess the acceptance of doctors toward the practice of reusing cardiac disposables in coronary angioplasty. Materials and Methods: An open-ended and self-designed questionnaire was prepared and was standardized by a panel of cardiologists to assess doctors' acceptance toward reusing cardiac disposable in coronary angioplasty. The cardiologists were interviewed individually, and the responses were analyzed. Results: The cardiologists were aware that the angioplasty disposables were being reused. The majority were satisfied with the sterilization of disposables and were of the opinion that it was safe for the patients. Cardiac catheters were reused 5-6 times while the balloons were reused 3-4 times. An increase in procedure time of 10-15 min was observed in 30% of the patients. There was an increase, in contrast, volume of about 40-50 mL with reused cardiac catheters and balloons which was observed in 15% of the patients. Defect in the physical integrity of the catheter, that is, tip abrasion/microfracture was observed in 1% of the patients. Deflation dysfunction of the balloon during the procedure was observed in 2% of the patients, while breakage of the balloon from the shaft and entanglement of the balloon was observed in 1% of the patients. Balloon rupture during angioplasty was observed in 8% of the patients. Around 1.5% of the patients undergoing angioplasty with reused disposables were presented with infections. Thrombosis was observed in 3% of the patients with reused disposables, and it was the most common adverse event post-angioplasty. There were cases where the patients were sent for emergency surgery/coronary artery bypass graft surgery due to balloon entanglement and about 0.1% of the patients were found to have such a complication. Conclusion: Cardiac disposables can be safely reused by health-care professionals, especially in developing nations due to their budget constraints, provided it is reused no more than 3-5 times and efficient methods of sterilization are observed. [ABSTRACT FROM AUTHOR]

Here, we demonstrate a self-sufficient, inexpensive and disposable pressure pump using commercially available latex balloons. The versatility of the pump is demonstrated against various microfluidic structures, liquid viscosities, and ambient temperatures. The flow rate of the pump can be controlled by varying the size and thickness of the balloon. Importantly, the soft structure of the balloon allows for almost instantaneous change of the flow rate upon manual squeezing of the balloon. This feature has been used for dynamically changing the flow ratio of parallel streams in a T-shaped channel or varying the size of droplets in a droplet generation system. The self-sufficiency, simplicity of fabrication and operation, along with the low-cost of the balloon pump facilitate the widespread application of microfluidic technologies for various research, education, and in situ monitoring purposes. [ABSTRACT FROM AUTHOR]

This paper investigates numerically the post-bifurcation evolution of ellipsoidal or spherical balloons subject to internal pressure, where the primary N -shaped curves of pressure vs. principal stretch and the corresponding bifurcated branch, i.e. pear-shaped deformation, are captured quantitatively. We quantify and discuss the range of pear-shaped bifurcation intervals of ellipsoids and the associated critical points. For rugby-shaped ellipsoidal balloons, we find that there exists a threshold for the aspect ratio of the major and minor axes that leads to pear-shaped bifurcation, which is detected by the finite element method. When the rugby shape becomes sufficiently slender, the nonlinear response of the ellipsoidal balloons is well approximated by the deformation of a tube with localized bulging instead of pear-shaped configuration. We obtain the nonlinear evolution of the localized bulging of rugby-like ellipsoids numerically. Furthermore, we examine the influence of various aspect ratios for rugby-shaped balloons on the localized bulging response. We find that pumpkin-shaped ellipsoids can always bifurcate into pear shape. Lastly, we provide a unified phase diagram on instability mode selection of various aspect ratios of ellipsoidal balloons, with diverse representative deformed configurations. [ABSTRACT FROM AUTHOR]

With the discovery of gravitational waves (GWs), attention has turned towards detecting counterparts to these sources. In discussions on counterpart signatures and multimessenger follow-up strategies to the GW detections, ultraviolet (UV) signatures have largely been neglected, due to UV facilities being limited to SWIFT, which lacks high-cadence UV survey capabilities. In this paper, we examine the UV signatures from merger models for the major GW sources, highlighting the need for further modelling, while presenting requirements and a design for an effective UV survey telescope. Using the u'-band models as an analogue, we find that a UV survey telescope requires a limiting magnitude of mu'(AB) ≈ 24 to fully complement the aLIGO range and sky localization.We show that a network of small, balloonbased UV telescopes with a primary mirror diameter of 30 cm could be capable of covering the aLIGO detection distance from ~60 to 100 per cent for BNS events and ~40 per cent for the black hole and a neutron star events. The sensitivity of UV emission to initial conditions suggests that a UV survey telescope would provide a unique data set, which can act as an effective diagnostic to discriminate between models. [ABSTRACT FROM AUTHOR]

This paper is intended to supplement one published in 1966 containing a survey of the literature on yarn hairiness, and the review of the literature is brought up-to-date at the time of writing. A new electronic instrument for measuring yarn hairiness is outlined. This apparatus enables three parameters to be obtained directly and simultaneously, these being hairiness, hair length, and yarn diameter. [ABSTRACT FROM AUTHOR]

This paper describes a comprehensive simulation for high altitude zero pressure balloon trajectories. A mathematical model was established to simulate the ascending process which considers the atmospheric conditions and thermodynamic variations. Influences of launch parameters on ascending performance were analyzed. The necessary quantity of initial lift gas was estimated and optimized, so that ensures no ballast consuming during the ascending process. The climbing rate was a governing parameter to evaluate the ascending performance. Based on the simulation, results revealed the apparent different effect on climbing rate at troposphere and stratosphere layers. Change in launch time and site mainly affect the climbing rate at the stratosphere and have no significant effect at the troposphere and tropopause altitudes. Meanwhile, change in launch date has a negligible effect on both layers. Due to the earth's declination angle, the influence of the same launch latitude and the same launch longitude is not identical within a year. Also, results showed that the optimum lift gas quantity improved the climbing rate stability to obtain an accurate simulation. [ABSTRACT FROM AUTHOR]

Since the International Geophysical Year (1957), the Lebedev Physical Institute performs the regular measurements of charged particle fluxes in the Earth's atmosphere (from the ground level up to 30–35 km) at several latitudes. The unique experimental data base obtained during 58 years of cosmic rays observations in the atmosphere allows to investigate temporal, spatial and energetic characteristics of galactic and solar cosmic rays as well as the role of charged particles in the atmospheric processes. Analysis of this data base also revealed a special class of numerous events caused by energetic electron precipitation recorded in the atmosphere at polar latitudes. In this paper we present Catalogue of electron precipitation events observed in the polar atmosphere during 1961–2014 and briefly outline the previous results of this data set analysis. [ABSTRACT FROM AUTHOR]

It is previously known that under inflation alone a spherical rubber membrane balloon may bifurcate into a pear shape when the tension in the membrane reaches a maximum, but the existence of such a maximum depends on the material model used: the maximum exists for the Ogden model, but does not exist for the neo-Hookean, Mooney–Rivlin or Gent model. This paper discusses how such a situation is changed when a pressurized dielectric elastomer balloon is subjected to additional electric actuation. A similar bifurcation condition is first deduced and then verified numerically by computing the bifurcated solutions explicitly. It is shown that when the material is an ideal dielectric elastomer, bifurcation into a pear shape is possible for all material models, and similar results are obtained when a typical non-ideal dielectric elastomer is considered. It is further shown that whenever a pear-shaped configuration is possible it has lower total energy than the co-existing spherical configuration. [ABSTRACT FROM AUTHOR]

This paper investigates the accuracy of simulated long-duration super-pressure balloon trajectories in the lower stratosphere. The observed trajectories were made during the (tropical) Pre-Concordiasi and (polar) Concordiasi campaigns in 2010, while the simulated trajectories are computed using analyses and forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System model. In contrast with the polar stratosphere situation, modelling accurate winds in the tropical lower stratosphere remains challenging for numerical weather prediction systems. The accuracy of the simulated tropical trajectories are quantified with the operational products of 2010 and 2016 in order to understand the impact of model physics and vertical resolution improvements. The median errors in these trajectories are large (typically ≳250 km after 24 h), with a significant negative bias in longitude, for both model versions. In contrast, using analyses in which the balloon-borne winds have been assimilated reduces the median error in the balloon position after 24 h to ∼60 km. For future campaigns, we describe operational strategies that take advantage of the geographic distribution and the episodic nature of large error events to anticipate the amplitude of error in trajectory forecasts. We finally stress the importance of a high vertical resolution in the model, given the intense shears encountered in the tropical lower stratosphere. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to assess the mid‐term efficacy and safety of adjustable continence therapy (ProACT™) for the treatment of male stress urinary incontinence (SUI) after radical prostatectomy (RP). Patients and Methods: Single‐center retrospective study including male patients implanted with ProACT™ periurethral balloons for SUI after RP between 2007 and 2017, mainly with flexible cystoscopic guidance. Efficacy was assessed using a composite endpoint with subjective (patient's impression of improvement (PII), using a 0–100 numeral rating scale) and objective outcomes (decrease in daily pad use). Postoperative success was defined as a PII ≥ 80%, associated with the use of 0–1 pad daily. Improvement was defined as a PII ≥ 50% and a decrease ≥50% in the number of daily pads used. Results: Two hundred men with a median age of 68 (64–73) years were included. Seventeen percent (n = 34) had had prior radiotherapy and 15.5% (n = 31) had had prior SUI surgery. The median follow‐up was 43 (19–71) months. The severity of SUI was as follows: mild in 119 (59.5%), moderate in 48 (24%), and severe in 33 patients (16.5%). Severe SUI and a history of prior radiotherapy were associated with a lower success rate (p = 0.033 and p < 0.0001). The overall reoperation rate was 34%, with 5.6% (n = 11) requiring a third implantation. Of the patients, 29.4% (n = 58) required an artificial urinary sphincter to treat SUI. At the last follow up, among the overall population, the success rate was 40.1% and the median PII was 18.3%. For patients in whom the balloons were still in place (n = 132), the cumulative success and improvement rate was 78%, with a median PII of 72%. Conclusion: The minimally invasive ProACT™ device provides a clear beneficial continence outcome in patients with SUI after radical prostatectomy. Severe SUI or prior radiotherapy were associated with a lower success rate in our study. [ABSTRACT FROM AUTHOR]

Prediction of thermal behavior and trajectory plays an important role in design and operation of stratospheric balloons. First, a more rounded and improved thermal and vertical trajectory model for performance prediction of stratospheric super-pressure balloons is established, including thermal models for solar radiation, infrared radiation, heat convection, and vertical dynamic model. Meanwhile, mathematical models for gas expulsion and ballast drop are also established. The new model is suitable for both the ascent stage and floating condition of stratospheric super-pressure balloon. Then, a computer program is developed based on the improved model, and predicting accuracy of the model is verified using experimental results of a stratospheric balloon. In the end, performance parameters of a new concept stratospheric balloon in ascent stage and floating condition are obtained, including film temperature, helium gas temperature, pressure differential, altitude, and velocity. Simulation results show that stratospheric balloons experience supercooling and superheating in the ascent stage and floating condition respectively, and both helium gas temperature and difference pressure have great change from day to night in the floating condition. [ABSTRACT FROM AUTHOR]

Wind measurement is crucial for wind energy assessment and development of wind farms. For conventional measurement, wind sensors are implemented on a wind mast at desired heights. This approach causes substantial costs of construction, time, and maintenance. The paper presents a simple low-cost method of wind measurement via interpreting dynamic behaviors of a helium balloon. A helium balloon is installed at the desired height where it is pulled by a cord of corresponding length. The end of the cord is tied to a specially designed holding mechanism of a rotating arm, which always leads to direction of wind. For wind speed, aerodynamic performance of the helium balloon is numerically investigated by mathematical models. It is found that drag force due to wind through the helium balloon dynamically balances forces of buoyancy, gravity, and tension. Therefore, wind speed at the balloon height can be determined from motion equations and drag equation since variables of the helium balloon are measured such as the swing angle away from vertical line and cord tension. By applying the wind profile power law, the wind speed data at the balloon height can be further adjusted to the values at the desired height. Experiments in a field study are readily performed to show great viability of the proposed methodology. [ABSTRACT FROM AUTHOR]

Reports on the early beginnings and development of biomedical engineering focusing on Dov Jaron?s work on the balloon pump and his efforts to increase the visibility of biomedical engineering as a professional field. [ABSTRACT FROM PUBLISHER]

Inflation of balloons provides a straightforward way of achieving large biaxial deformations. Previous studies have shown that when a balloon bursts, crack propagation occurs at very high speed – much higher than would be expected from the low strain modulus and elastic wave velocity of the rubber. The present paper is concerned with studies of the deformation and fracture of cylindrical balloons. On inflation, the deformations of such a balloon pass through an unstable region but subsequently increase monotonically with pressure. In this relatively high pressure region, the ratio of the longitudinal and circumferential extension ratios is broadly in accord with expectations from high-strain elasticity theory when the ratio of the corresponding stresses is taken into account. On bursting, crack speeds up to around 300 m/s in this region. It is shown that these speeds are in accord with large increase in incremental moduli for the highly-strained rubber. Marked changes in crack tip profile observed at very high crack speeds are consistent with control of the rate of growth by inertia rather than by the viscoelastic properties of the rubber (as is believed to be the case at lower speeds). Consistent with this, various elastomers having different glass transition temperatures show similar crack growth behaviour in the very high speed region. [ABSTRACT FROM AUTHOR]

Abstract: This paper outlines an analytical model to predict the temperature of fully-inflated balloon on float at high altitude in stratosphere. Simplified radiative and convective heat transfer models are developed to estimate absorption and emission heat of balloon film and lifting gas within balloon. Thermal equilibrium equations for the balloon system in the day time and night time are derived by incorporating radiative and convective heat transfer models. The new model is applied to calculate the day and night temperatures of the balloon system on float at a high-altitude in stratosphere and reasonable correlation is achieved between the predictions obtained from new models and from prior flight testing data, demonstrating the effective use of the proposed models. [Copyright &y& Elsevier]

Endovascular procedures for the management of the superficial femoral (SFA) and popliteal artery disease are increasingly common. Over the past decade, several stent technologies have been established which may offer new options for improved clinical outcomes. This paper reviews the current evidence for SFA and popliteal artery angioplasty and stenting, with a focus on randomized trials and registries of nitinol self-expanding stents, drug-eluting stents, dug-coated balloons, and covered stent-grafts. We also highlight the limitations of the currently available data and the future routes in peripheral arterial disease (PAD) stent and balloon technology. [ABSTRACT FROM AUTHOR]

This article seeks to outline novel simplified model and analytical solution for predicting geometrical shape and film tension of high-altitude balloon. Sphero-conical and ellipsoid-conical models were proposed to depict geometrical configuration of high-altitude balloon subjected to a payload. By considering the effect of atmospheric factors and lifting gas temperature on geometrical shape of balloon, geometrical parameters of equilibrium shape were solved, based on minimum potential energy principle satisfying material constraint. New analytical solution was derived to allow balloon film tensions in meridional and circumferential directions. Finally, new model and its solution were used for predicting geometrical shape and film tension of natural-shape balloon on the ground and on float in stratosphere respectively, demonstrating the practical and effective use of the proposed model. [ABSTRACT FROM AUTHOR]

Abstract: A detailed characterization of the formation and evolution of Venus is a key link to the study of terrestrial planets, and to their divergent evolutions. While Earth and to a lesser extent Mars (thanks to the analysis of SNC meteorites) are extensively studied in a comparative planetology context, the history of the most Earth-like planet of the Solar System, Venus, is still poorly understood. For how long has Venus been in its current extreme climate state? When and how did it diverge from a (possible) early Earth-like state? Has Venus been a potentially habitable planet at some time of its early history? Did a “cool early Venus” stage occur between the end of accretion and the late heavy bombardment, like suspected for Earth? What are the implications of the Venus/Earth comparison for the nature and evolution of habitable terrestrial planets throughout the universe? A major observational missing link in our understanding of Venus'' climate evolution is the elementary and isotopic pattern of noble gases and of stable isotopes in Venus'' atmosphere, still poorly known. The concentrations of heavy noble gases (Kr, Xe) and their isotopes are mostly unknown, and our knowledge of light noble gases and stable isotopes is incomplete and inaccurate. In this paper, we summarize our present understanding of Venus'' early evolution, including the crucial question of knowing if water ever condensed at the surface of the planet. Then, we assess the potential contribution of a precise measurement of noble gases, their isotopes and stable isotopes to improve of our understanding of Venus evolution, and list the main questions that noble gases and isotope measurements would help to answer. Finally, we show how future exploration of Venus could allow to gain a glimpse into the early evolution of Venus through a small in-situ mission based on a single balloon probe, called EVE (European Venus Explorer), proposed in the frame of the ESA Cosmic Vision program. [Copyright &y& Elsevier]

Abstract: The design and operation of a high altitude scientific balloon requires adequate knowledge of the thermal characteristics of the balloon to make it safe and reliable. The thermal models and dynamic models of altitude scientific balloons are established in this paper. Based on the models, a simulation program is developed. The thermal performances of a super pressure balloon are simulated. The influence of film radiation property and clouds on balloon thermal behaviors is discussed in detail. The results are helpful for the design and operate of safe and reliable high altitude scientific balloons. [Copyright &y& Elsevier]

Abstract: The paper presents experimental and processed data of gas permeation through stretched polyisoprene rubber membranes. As a consequence of the membrane stretching, the polymer chains flexibility decreases and the penetrant path length increases. Gas diffusion, solubility and permeability coefficients depend on stretching intensity. Two methods were used to estimate the permeability coefficients of pure gases, i.e. hydrogen, oxygen, nitrogen, methane and carbon dioxide. A dynamic method was based on volume and pressure measurements of rubber balloons filled with gas. A time-lag method was employed to study the gas permeation through rubber membranes placed in a permeation cell. Both methods gave comparable results. [Copyright &y& Elsevier]

A vexing conundrum that has hindered the development of a high-altitude heavy-lift pumpkin balloon system is the system's ability to reliably deploy into the desired symmetric shape. With design strategies honed by empirical results from inflation tests in 2007 using 27-m-diam 200-gore pumpkin balloons, NASA's Balloon Program Office executed successful pumpkin deployments in 2008: Flight 586-NT, a 2 million cubic foot 200-gore design, and Flight 591-NT, a 6 million ft³ 200-gore design. Earlier stability analysis of strained symmetric float shapes yielded partial information regarding deployment. Balloons that were found to have a large number of unstable modes at float conditions were found also to have deployment problems. The question remained, what was the minimum pressure at which a pumpkin balloon would deploy into a cyclically symmetric shape (not necessarily the fully developed one)? Careful examination of a family of axisymmetric ascent shapes revealed a correlation between differential pressure and the number of unstable modes. In this paper, criteria that can be used to estimate the deployment pressure is presented. To bound the problem, fixed-, constrained-, and free-boundary conditions are considered for the top endplate fitting. It was found that the stability results using the fixed and constrained conditions are nearly identical, and so the strategy for estimating the deployment pressure, called the deployment pathway portrait, is as follows. The deployment pressure PDep is defined as the smallest nadir pressure where the top-free boundary condition yields two unstable modes and the top-fixed boundary condition yields no unstable modes. The approach is validated by comparing analytical predictions of deployment pressures based on the deployment pathway portrait with the deployment pressures that were recorded during the inflation tests in 2007: Flight 586-NT and Flight 591-NT. Very good agreement between the observed deployment pressures and the analytical predictions was found. This is the first analytical-based approach for estimating the deployment pressure. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the optimization of the cutting pattern of n-fold symmetric super-pressure balloons made from identical lobes constrained by stiff meridional tendons. It is shown that the critical buckling pressure of such balloons is maximized if the unstressed surface area of the balloon is minimized under a stress constraint. This approach results in fully stressed balloon designs that in some cases have a smaller unstressed surface area than the corresponding axisymmetric surface that is in equilibrium with zero hoop stress. It is shown that, compared to current designs, the buckling pressures can be increased by up to 300% without increasing the maximum stress in the lobe. [Copyright &y& Elsevier]

Abstract: In order to provide scientists with a stratospheric platform from which to conduct long duration research, a superpressure balloon is desired which will maintain a relatively constant volume for weeks at a time. The pumpkin shaped balloon has been developed by making use of the surface lobing to limit the circumferential stress and meridional tendons to carry the loads in the other direction. However, in order to prevent geometric instabilities during deployment and after pressurization, the design should eliminate as much excess material as possible while not exceeding the permissible stresses of the material. This paper will describe the behavior of the very thin membrane material selected for this application and the limits of the film in a biaxial state of stress. In addition, it is shown that the viscoelastic nature of the film will limit the stress by causing a reduced radius of curvature in the lobe of the pumpkin. [Copyright &y& Elsevier]

This paper presents a simple two dimensional frame formulation to deal with structures undergoing large motions due to dynamic actions including very thin inflatable structures, balloons. The proposed methodology is based on the minimum potential energy theorem written regarding nodal positions. Velocity, acceleration and strain are achieved directly from positions, not displacements, characterizing the novelty of the proposed technique. A non-dimensional space is created and the deformation function (change of configuration) is written following two independent mappings from which the strain energy function is written. The classical Newmark equations are used to integrate time. Dumping and non-conservative forces are introduced into the mechanical system by a rheonomic energy function. The final formulation has the advantage of being simple and easy to teach, when compared to classical counterparts. The behavior of a bench-mark problem (spin-up maneuver) is solved to prove the formulation regarding high circumferential speed applications. Other examples are dedicated to inflatable and very thin structures, in order to test the formulation for further analysis of three dimensional balloons. [ABSTRACT FROM AUTHOR]