The Effect of Crystallization on the Pulsations of White Dwarf Stars

We consider the pulsational properties of white dwarf star models with temperatures appropriate for the ZZ Ceti instability strip and with masses large enough that they should be substantially crystallized. Our work is motivated by the existence of a potentially crystallized DAV, BPM 37093, and the expectation that digital surveys in progress will yield many more such massive pulsators. A crystallized core makes possible a new class of oscillations, the torsional modes, although we expect these modes to couple at most weakly to any motions in the fluid and therefore to remain unobservable. The p-modes should be affected at the level of a few percent in period, but are unlikely to be present with observable amplitudes in crystallizing white dwarfs any more than they are in the other ZZ Ceti's. Most relevant to the observed light variations in white dwarfs are the g-modes. We find that the kinetic energy of these modes is effectively excluded from the crystallized cores of our models. As increasing crystallization pushes these modes farther out from the center, the mean period spacing between radial overtones increases substantially with the crystallized mass fraction. In addition, the degree and structure of mode trapping is affected. The fact that some periods are strongly affected by changes in the crystallized mass fraction while others are not suggests that we may be able to disentangle the effects of crystallization from those due to different surface layer masses.Comment: 18 pages, 5 figures, accepted on 1999 July 2 for publication in the Astrophysical Journa

Final Version Zurich, 27th July 2010

Adaptation to climate change requires an integrated risk management approach, including risk assessment, prevention and insurance. Insurance solutions can potentially provide a significant contribution in expanding and strengthening adaptation response to climate change risks. Numerous proposals and submissions under the United Nations Framework Convention on Climate Change (UNFCCC) make reference to risk transfer and insurance solutions as a com- plementary element of a systematic adaptation approach, but no consensus has been achieved regarding their role and eventual implementation under UNFCCC. This paper intends to raise awareness on existing work and the current challenges related to climate relevant insurance, in developing countries and to contribute to a further discussion of the insurance topic under UNFCCC. Past experiences and discussions can provide a framework for larger policies on the role of insurance in the emerging climate financing architecture. Further pilot implementation, research, and systematic learning is required. Many of the elements such as data collection, research, ca- pacity building and exploration of public private partnerships are valuable for achieving broader adaptation objectives. It is therefore encouraged that the Parties further explore and define the scope of insurance solutions as part of climate change adaptation

The hydrogen and helium lines of the symbiotic binary Z And during its brightening at the end of 2002

High resolution observations in the region of the lines Halpha, He II 4686 and Hgamma of the spectrum of the symbiotic binary Z And were performed during its small-amplitude brightening at the end of 2002. The profiles of the hydrogen lines were double-peaked. These profiles give a reason to suppose that the lines can be emitted mainly by an optically thin accretion disc. The Halpha line is strongly contaminated by the emission of the envelope, therefore for consideration of accretion disc properties we use the Hgamma line. The Halpha line had broad wings which are supposed to be determined mostly from radiation damping but high velocity stellar wind from the compact object in the system can also contribute to their appearance. The Hgamma line had a broad emission component which is assumed to be emitted mainly from the inner part of the accretion disc. The line He II 4686 had a broad emission component too, but it is supposed to appear in a region of a high velocity stellar wind. The outer radius of the accretion disc can be calculated from the shift between the peaks. Assuming, that the orbit inclination can ranges from 47$^\circ$ to 76$^\circ$, we estimate the outer radius as 20 - 50 R_sun. The behaviour of the observed lines can be considered in the framework of the model proposed for interpretation of the line spectrum during the major 2000 - 2002 brightening of this binary.Comment: 19 pages, 5 figures. Accepted for publication in Astronomy Report

Illumination in symbiotic binary stars: Non-LTE photoionization models. II. Wind case

We describe a non-LTE photoionization code to calculate the wind structure and emergent spectrum of a red giant wind illuminated by the hot component of a symbiotic binary system. We consider spherically symmetric winds with several different velocity and temperature laws and derive predicted line fluxes as a function of the red giant mass loss rate, \mdot. Our models generally match observations of the symbiotic stars EG And and AG Peg for \mdot about 10^{-8} \msunyr to 10^{-7} \msunyr. The optically thick cross- section of the red giant wind as viewed from the hot component is a crucial parameter in these models. Winds with cross-sections of 2--3 red giant radii reproduce the observed fluxes, because the wind density is then high, about 10^9 cm^{-3}. Our models favor winds with acceleration regions that either lie far from the red giant photosphere or extend for 2--3 red giant radii.Comment: 51 pages, LaTeX including three tables, requires 15 Encapsulated Postscript figures, to appear in Ap

The role of the zeolite in the hydrogenolysis of C2 and C3 hydrocarbons on RuNaY catalysts

The catalytic properties for the hydrogenolysis of ethane, propane and cyclopropane of a series of highly dispersed RuNaY catalysts have been investigated. These catalysts have activities and selectivities for ethane and propane hydrogenolysis similar to other supported ruthenium catalysts. However, the activity of the RuNaY for cyclopropane hydrogenolysis is much higher than that of Ru on conventional oxide supports, while the selectivities remain in a range expected for well-dispersed ruthenium. The increase in activity for the RuNaY catalysts is due mainly to the presence of highly dispersed Ru particles made possible by the zeolite support. A destabilization of the cyclopropane ring by the electrostatic field of the zeolite, however, does not seem to contribute significantly to the observed rate increase. It appears that the ring opening of cyclopropane and the hydrogenolysis of cyclopropane to ethane and methane have a common intermediate, the formation of which is rate determining for both reactions. The discovery that on Ru the ring opening of cyclopropane is structure sensitive is surprising since this reaction is generally considered as a classic example for structure insensitivity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26286/1/0000371.pd

The research of automobile electric control bus technology based on CAN/LIN mixed protocol

传统汽车电气控制系统中采用的点对点通信方式，对于电子化程度越来越高的汽车而言，将使其线束十分复杂，不仅增加了电气系统成本，而且会因为节点繁多使系统运行可靠性降低。总线网络能够大量减少控制线数，提高可靠性，因此，采用总线控制成为汽车电气控制系统技术发展的必然趋势。如何在汽车上建立基于总线技术的汽车电气控制系统问题自然成为汽车电子领域广受关注的研究热点。西门子公司已经利用PLC完成CAN总线控制系统，由于其具有抗干扰性强、线路简化、传输速率高、系统可任意扩展等优点，正受到国内外高度重视，但其成本高，很多国内汽车生产厂家不能接受。在这种情形下，福州源光亚明电器有限公司（沈阳中顺汽车供应商）委托厦门大...The traditional automobile electrical control system used in peer-to-peer communications, the freetly increased electronic level of automobiel makes the wiring harness more complicated by which not only increases costs, but also lower the reliability of system because of the various nodes. Bus network can decrease the number of the control lines and increase the reliability greatly. Therefore, the...学位：工学硕士院系专业：物理与机电工程学院机电工程系_测试计量技术及仪器学号：2005130175

A Nonvolatile MOSFET Memory Device Based on Mobile Protons in SiO(2) Thin Films

It is shown how mobile H{sup +} ions can be generated thermally inside the oxide layer of Si/SiO{sub 2}/Si structures. The technique involves only standard silicon processing steps: the nonvolatile field effect transistor (NVFET) is based on a standard MOSFET with thermally grown SiO{sub 2} capped with a poly-silicon layer. The capped thermal oxide receives an anneal at {approximately}1100 C that enables the incorporation of the mobile protons into the gate oxide. The introduction of the protons is achieved by a subsequent 500-800 C anneal in a hydrogen-containing ambient, such as forming gas (N{sub 2}:H{sub 2} 95:5). The mobile protons are stable and entrapped inside the oxide layer, and unlike alkali ions, their space-charge distribution can be controlled and rapidly rearranged at room temperature by an applied electric field. Using this principle, a standard MOS transistor can be converted into a nonvolatile memory transistor that can be switched between normally on and normally off. Switching speed, retention, endurance, and radiation tolerance data are presented showing that this non-volatile memory technology can be competitive with existing Si-based non-volatile memory technologies such as the floating gate technologies (e.g. Flash memory)

Criticality of Low-Energy Protons in Single-Event Effects Testing of Highly-Scaled Technologies

We report low-energy proton and low-energy alpha particle single-event effects (SEE) data on a 32 nm silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) latches and static random access memory (SRAM) that demonstrates the criticality of using low-energy protons for SEE testing of highly-scaled technologies. Low-energy protons produced a significantly higher fraction of multi-bit upsets relative to single-bit upsets when compared to similar alpha particle data. This difference highlights the importance of performing hardness assurance testing with protons that include energy distribution components below 2 megaelectron-volt. The importance of low-energy protons to system-level single-event performance is based on the technology under investigation as well as the target radiation environment

Proton Irradiation Effects in Oxide-Confined Vertical Cavity Surface Emitting Laser (VCSEL) Diodes

Recent space experience has shown that the use of commercial optocouplers can be problematic in spacecraft, such as TOPEX/Poseidon, that must operate in significant radiation environments. Radiation--induced failures of these devices have been observed in space and have been further documented at similar radiation doses in the laboratory. The ubiquitous use of optocouplers in spacecraft systems for a variety of applications, such as electrical isolation, switching and power transfer, is indicative of the need for optocouplers that can withstand the space radiation environment. In addition, the distributed nature of their use implies that it is not particularly desirable to shield optocouplers for use in radiation environments. Thus, it will be important for the space community to have access to radiation hardened/tolerant optocouplers. For many microelectronic and photonic devices, it is difficult to achieve radiation hardness without sacrificing performance. However, in the case of optocouplers, one should be able to achieve both superior radiation hardness and performance for such characteristics as switching speed, current transfer ratio (CTR), minimum power usage and array power transfer, if standard light emitting diodes (LEDs), such as those in the commercial optocouplers mentioned above, are avoided, and VCSELs are employed as the emitter portion of the optocoupler. The physical configuration of VCSELs allows one to achieve parallel use of an array of devices and construct a multichannel optocoupler in the standard fashion with the emitters and detectors looking at each other. In addition, detectors similar in structure to the VCSELs can be fabricated which allows bidirectional functionality of the optocoupler. Recent discussions suggest that VCSELs will enjoy widespread applications in the telecommunications and data transfer fields

Unlocking data: Federated identity with LSDMA and dCache

X.509, the dominant identity system from grid computing, has proved unpopular for many user communities. More popular alternatives generally assume the user is interacting via their web-browser. Such alternatives allow a user to authenticate with many services with the same credentials (user-name and password). They also allow users from different organisations form collaborations quickly and simply. Scientists generally require that their custom analysis software has direct access to the data. Such direct access is not currently supported by alternatives to X.509, as they require the use of a web-browser. Various approaches to solve this issue are being investigated as part of the Large Scale Data Management and Analysis (LSDMA) project, a German funded national R&D project. These involve dynamic credential translation (creating an X.509 credential) to allow backwards compatibility in addition to direct SAML- and OpenID Connect-based authentication. We present a summary of the current state of art and the current status of the federated identity work funded by the LSDMA project along with the future road map