10,057 research outputs found

    Positron-inert gas differential elastic scattering

    Get PDF
    Measurements are being made in a crossed beam experiment of the relative elastic differential cross section (DCS) for 5 to 300 eV positrons scattering from inert gas atoms (He, Ne, Ar, Kr, and Xe) in the angular range from 30 to 134 deg. Results obtained at energies around the positronium (Ps) formation threshold provide evidence that Ps formation and possibly other inelastic channels have an effect on the elastic scattering channel

    Applications of satellite technology to broadband ISDN networks

    Get PDF
    Two satellite architectures for delivering broadband integrated services digital network (B-ISDN) service are evaluated. The first is assumed integral to an existing terrestrial network, and provides complementary services such as interconnects to remote nodes as well as high-rate multicast and broadcast service. The interconnects are at a 155 Mbs rate and are shown as being met with a nonregenerative multibeam satellite having 10-1.5 degree spots. The second satellite architecture focuses on providing private B-ISDN networks as well as acting as a gateway to the public network. This is conceived as being provided by a regenerative multibeam satellite with on-board ATM (asynchronous transfer mode) processing payload. With up to 800 Mbs offered, higher satellite EIRP is required. This is accomplished with 12-0.4 degree hopping beams, covering a total of 110 dwell positions. It is estimated the space segment capital cost for architecture one would be about 190Mwhereasthesecondarchitecturewouldbeabout190M whereas the second architecture would be about 250M. The net user cost is given for a variety of scenarios, but the cost for 155 Mbs services is shown to be about $15-22/minute for 25 percent system utilization

    Upaya Pemerintah Desa dalam Meningkatkan Kualitas Pelayanan pada Masyarakat

    Full text link
    Abstraction This Base On Reality That which Indicate Still There are many Deficient in And Mistrust hello world In The government The village,Then Study Concerning The effort BecomeVery Relevant To Raised. The implication of The application Service The area also Sue The village DoVarious Multiform Renewal InInternally AsWas prosecuted By Services.The renewal of this Just possible Done Manakalah The government The village Already Capable of being Empowering Her.To depart From thinking The thenViewed Need Do Study hello word The government hello word To Good Service On People.Formulating The problem In Research It is How Conditions The The villagers Lismanggu Viewed from Conditions Three Or actor Acolonnade Government Existing.And what is the Berdayaan of The The government Villages District Prafi A county Manokwari And post-conflict -upaya what Should Done in The implementation of the village.An inference It is obtainable In order to Upayan government Divided into the three concepts Governments and government The village, a body of s consultative The village, civil society Village and sub-district prafi while.The effort That is over This Made to empower Or improve Capacity The government has yet to Optimal and have not shown The act of one who Sistematiik( still half-hearted and partial )And Concentrated On the fields A particular.Our suggest ions The ask is The village was, okay Who muflak to Done.An effort made By integrating Various needs,Every actor And the approach A systemic.The Government Regency expected more focus attention Organization of theT he village Government efforts throughthe granting of the aid in the form of the allocation offunds for implementation of the Government's efforts of village Lismanggu district prafi district of Manokwari

    Space-charge-limited flows in the quantum regime

    Full text link
    This paper reviews the recent developments of space-charge-limited (SCL) flow or Child-Langmuir (CL) law in the quantum regime. According to the classical CL law for planar diodes, the current density scales as 3/23∕2’s power of gap voltage and to the inverse squared power of gap spacing. When the electron de Broglie wavelength is comparable or larger than the gap spacing, the classical SCL current density is enhanced by a large factor due to electron tunneling and exchange-correlation effects, and there is a new quantum scaling for the current density, which is proportional to the 1/21∕2’s power of gap voltage, and to the inverse fourth-power of gap spacing. It is also found that the classical concepts of the SCL flow such as bipolar flow, transit time, beam-loaded capacitance, emitted charge density, and magnetic insulation are no longer valid in quantum regime. In the quantum regime, there exists a minimum transit time of the SCL flows, in contrast to the classical solution. By including the surface properties of the emitting surface, there is a threshold voltage that is required to obtain the quantum CL law. The implications of the Fowler-Nordheim-like field emission in the presence of intense space charge over the nanometer scale is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87757/2/056701_1.pd

    Lightweight Ceramics for Aeroacoustic Applications

    Get PDF
    The use of a HTP (High Temperature Performance) ceramic foam for aeroacoustic applications is investigated. HTP ceramic foam is a composition of silica and alumina fibers developed by LMMS. This foam is a lightweight high-temperature fibrous bulk material with small pore size, ultra high porosity, and good strength. It can be used as a broadband noise absorber at both room and high temperature (up to 1800 F). The investigation included an acoustic assessment as well as material development, and environmental and structural evaluations. The results show that the HTP ceramic foam provides good broadband noise absorbing capability and adequate strength when incorporating the HTP ceramic foam system into a honeycomb sandwich structure. On the other hand, the material is sensitive to Skydrol and requires further improvements. Good progress has been made in the impedance model development. A relationship between HTP foam density, flow resistance, and tortuosity will be established in the near future. Additional effort is needed to investigate the coupling effects between face sheet and HTP foam material
    • …
    corecore