17,513 research outputs found

    Implications of Heavy Top

    Full text link
    Lecture at 23 ITEP Winter School. Manifestations of heavy top at low energies (K- and B-mesons) and high energies (Z and W physics) are discussedComment: 12 pages; ps file can be found at http://venus.itep.ru/preprints/1995/95046.ps.g

    Photometry of the SW Sex-type nova-like BH Lyncis in high state

    Full text link
    Aims: We present a photometric study of the deeply eclipsing SW Sex-type nova-like cataclysmic variable star BH Lyn Methods: Time-resolved V-band CCD photometry was obtained for seven nights between 1999 and 2004. Results: We determined 11 new eclipse timings of BH Lyn and derived a refined orbital ephemeris with an orbital period of 0.155875577(14) day. During the observations, BH Lyn was in high-state with V~15.5 mag. The star presents ~1.5 mag deep eclipses with mean full-width at half-flux of 0.0683(+/-0.0054)P_orb. The eclipse shape is highly variable, even changing form cycle to cycle. This is most likely due to accretion disc surface brightness distribution variations, most probably caused by strong flickering. Time-dependent accretion disc self-occultation or variations of the hot spot(s) intensity are also possible explanations. Negative superhumps with period of ~0.145 day are detected in two long runs in 2000. A possible connection between SW Sex and negative superhump phenomena through the presence of tilted accretion disc is discussed, and a way to observationally test this is suggested

    Electric propulsion options for the SP-100 reference mission

    Get PDF
    Analyses were performed to characterize and compare electric propulsion systems for use on a space flight demonstration of the SP-100 nuclear power system. The component masses of resistojet, arcjet, and ion thruster systems were calculated using consistent assumptions and the maximum total impulse, velocity increment, and thrusting time were determined, subject to the constraint of the lift capability of a single Space Shuttle launch. From the study it was found that for most systems the propulsion system dry mass was less than 20 percent of the available mass for the propulsion system. The maximum velocity increment was found to be up to 2890 m/sec for resistojet, 3760 m/sec for arcjet, and 23 000 m/sec for ion thruster systems. The maximum thruster time was found to be 19, 47, and 853 days for resistojet, arcjet, and ion thruster systems, respectively

    NEUROELECTRIC THERAPY (NET) IN ADDICTION DETOXIFICATION

    Get PDF
    NeuroElectric Therapy (NET) is a benign and rapid, non-pharmacological detoxification treatment for the chemical dependent, either in-patient or out-patient, using very small amounts of electric current transcranially, with electtodes applied above the mastoid process. The pocketsize stimulator is used continuously for 7 to 10 days (3-4 days for nicotine), without supplementary drugs. Within this treatment period it eliminates the acute symptoms and also ameliorates the Chtonic Withdrawal Syndrome, which otherwise could last 18 months or longer, to a very substantial degree. By the end of treatment, 95% of 102 consecutive patients claimed they were free of craving, 75% that they were free of anxiery. NET has a reported drop-out rate of 1.6% over a period of seven years. The basis of this therapeutic success has been the marriage of precision clinical techniques to highly specific combinations of electrical current parameters, both developed over 20 years of reported clinical and research work. It is suggested that the mechanism of action may be the rapid restoration to normal of abnormal neurotransmitter levels by specific electrical signals. Clinical treatments and double-blind studies are briefly described and reviewed, with new data on sleep effects

    A Remarkable Example of Bubble Nucleation Suppression

    Get PDF
    Suppression of cavitation is a relatively common goal of fluid engineers and therefore examples of bubble nucleation suppression in other technological contexts are useful in suggesting ways in which such suppression might be achieved. In this paper we describe a remarkable example of bubble nucleation suppression achieved by a combination of the elimination of nucleation sites and the reduction of bubble growth time. The context is the invention of a device that allows the injection of aqueous solutions highly supersaturated with oxygen into the bloodstream without the formation of significant gaseous oxygen bubbles

    Xenon ion propulsion for orbit transfer

    Get PDF
    For more than 30 years, NASA has conducted an ion propulsion program which has resulted in several experimental space flight demonstrations and the development of many supporting technologies. Technologies appropriate for geosynchronous stationkeeping, earth-orbit transfer missions, and interplanetary missions are defined and evaluated. The status of critical ion propulsion system elements is reviewed. Electron bombardment ion thrusters for primary propulsion have evolved to operate on xenon in the 5 to 10 kW power range. Thruster efficiencies of 0.7 and specific impulse values of 4000 s were documented. The baseline thruster currently under development by NASA LeRC includes ring-cusp magnetic field plasma containment and dished two-grid ion optics. Based on past experience and demonstrated simplifications, power processors for these thrusters should have approximately 500 parts, a mass of 40 kg, and an efficiency near 0.94. Thrust vector control, via individual thruster gimbals, is a mature technology. High pressure, gaseous xenon propellant storage and control schemes, using flight qualified hardware, result in propellant tankage fractions between 0.1 and 0.2. In-space and ground integration testing has demonstrated that ion propulsion systems can be successfully integrated with their host spacecraft. Ion propulsion system technologies are mature and can significantly enhance and/or enable a variety of missions in the nation's space propulsion program

    Injection of Highly Supersaturated Oxygen Solutions without Nucleation

    Get PDF
    It is possible to inject highly supersaturated aqueous solutions of gas through a small capillary into an aqueous environment without the formation of significant gas bubbles. Such a technique has considerable potential therapeutic value in the treatment, for example, of heart attacks and strokes. The present paper is the second in a series (see Brereton et al. [1]) investigating the basic phenomenon behind this surprising effect. Recent experiments clearly demonstrate that the nucleation, when it does occur, results from heterogeneous nucleation on the interior surface of the distal end of the capillary. This paper describes the effects of the treatment of this interior surface on the nucleation processes and the results of high speed video observations of the phenomena. A heterogeneous nucleation model is presented which is in accord with the experimental observations

    Electrochemical Energy Storage Subsystems Study, Volume 2

    Get PDF
    The effects on life cycle costs (LCC) of major design and performance technology parameters for multi kW LEO and GEO energy storage subsystems using NiCd and NiH2 batteries and fuel cell/electrolysis cell devices were examined. Design, performance and LCC dynamic models are developed based on mission and system/subsystem requirements and existing or derived physical and cost data relationships. The models are exercised to define baseline designs and costs. Then the major design and performance parameters are each varied to determine their influence on LCC around the baseline values
    • …
    corecore