497 research outputs found
Commissioning results of the HZB Quadrupole Resonator
Recent cavity results with niobium have demonstrated the necessity of a good understanding of both the BCS and residual resistance. For a complete picture and comparison with theory, it is essential that one can measure the RF properties as a function of field, temperature, frequency and ambient magnetic field. Standard cavity measurements are limited in their ability to change all parameters freely and in a controlled manner. On the other hand, most sample measurement setups operate at fairly high frequency, where the surface resistance is always BCS dominated. The quadrupole resonator, originally developed at CERN, is ideally suited for characterization of samples at typical cavity RF frequencies. We report on a modified version of the QPR with improved RF figures of merit for high field operation. Experimental challenges in the commissioning run and alternate designs for simpler sample changes are shown alongside measurement results of a large grain niobium sampl
Time-varied daylighting performance to enable a goal-driven design process
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 140-152).Due to the overwhelming number of decisions to be made during early stage design, there is a need for intuitive methods to communicate data so that it is quickly and easily understood by the designer. In daylighting analysis, research has been moving towards dynamic daylighting metrics, which include both annual performance indicators and local climate conditions. Temporally-based graphics are one method of annual data display which shows great promise for use in the early design stage. Not only can temporal data be easily connected to time-dependent environmental variables like weather and solar angle, but non-spatial quantities related to solar heat gain can be compared on the same terms with spatial quantities like illuminance. This thesis demonstrates methods for quickly calculating annual data sets for which temporal maps are the intended display format. Metrics are then developed in order to display goal-based performance information for an entire area of interest on a single temporal map. This process is demonstrated first by reducing the number of simulations necessary to produce reliable annual illuminance data, the results of which are compiled into a metric based on a user-given illuminance range, known as Acceptable Illuminance Extent (AIE). Similarly, a geometry-based glare approximation method is developed and validated for quick annual calculations of Daylight Glare Probability, and the results are condensed to a single number representative of glare perception within the model, known as Glare Avoidance Extent (GAE).(cont.) Finally, a simple solar heat gain indicator is demonstrated using the Balance Point calculation method and the metric Solar Heat Scarcity/Surplus (SHS) is used to convey the urgency of allowing more direct solar gain or shading it. This thesis is part of the Lightsolve project, which aims to specifically address the needs of the architect during early design stages. Specifically, Lightsolve aims to produce fast, unique design analyses, based on local annual climate data with reasonably accurate and intuitive outputs to promote good decision-making. Such resources could enable a desirable shift in schematic stage design practices and move daylighting analysis one step closer to achieving "best practice" recognition.by Siân Alexandra Kleindienst.Ph.D
Observer design for a nonlinear heat equation: Application to semiconductor wafer processing
In this paper, the problem of observer design for a class of 1D nonlinear heat equations with pointwise in-domain temperature measurements is addressed. A pointwise measurement injection observer is designed and the robust convergence of its estimation error in presence of bounded distributed perturbations is established by verifying input-to-state stability. The obtained convergence conditions express the underlying interplay between heat conduction and radiation and include specific dependencies on the sensor locations which are the main degrees of freedom in the design approach. The theoretical results are experimentally validated on a semiconductor wafer processing unit
RIM-Binding Protein 2 organizes Ca2+channel topography and regulates release probability and vesicle replenishment at a fast central synapse
RIM-Binding Protein 2 (RIM-BP2) is a multi-domain protein of the presynaptic active zone (AZ). By binding to Rab-interacting protein (RIM), bassoon and voltage-gated Ca²⁺channels (CaV), it is considered to be a central organizer of the topography of CaVand release sites of synaptic vesicles (SVs) at the AZ. Here, we investigated the role of RIM-BP2 at the endbulb of Held synapse of auditory nerve fibers with bushy cells of the cochlear nucleus, a fast relay of the auditory pathway with high release probability. Disruption of RIM-BP2 lowered release probability altering short-term plasticity and reduced evoked excitatory postsynaptic currents (EPSCs). Analysis of SV pool dynamics during high frequency train stimulation indicated a reduction of SVs with high release probability but an overall normal size of the readily releasable SV pool (RRP). The Ca2+-dependent fast component of SV replenishment after RRP depletion was slowed. Ultrastructural analysis by super-resolution light and electron microscopy revealed an impaired topography of presynaptic CaVand a reduction of docked and membrane-proximal SVs at the AZ. We conclude that RIM-BP2 organizes the topography of CaV, and promotes SV tethering and docking. This way RIM-BP2 is critical for establishing a high initial release probability as required to reliably signal sound onset information that we found to be degraded in bushy cells of RIM-BP2-deficient mice in vivo
Report to the supreme council of antiquities on the 2001-2002 field season of the Dakhleh Oasis project
Report to the supreme council of antiquities on the 2001-2002 field season of the Dakhleh Oasis project
Volatiles in the Desert: Subtle Remote-sensing Signatures of the Dakhleh Oasis Catastrophic Event, Western Desert, Egypt
Over the past decade members of the Dakhleh Oasis Project have studied enigmatic signatures in the Pleistocene geologic record of portions of the Dakhleh oasis and palaeo-oasis in Egypt's Western Desert [1,2]. In particular, Si-Ca-Al rich glass melt (Dakhleh Glass, Fig. 1) points to a catastrophic event between c.100,000-200,000 years ago [3] in this well-studied African savannah and freshwater lake Middle Stone Age environment [4,5]
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Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley
Petroleum and dairy operations are prominent sources of gas-phase organic compounds in California's San Joaquin Valley. It is essential to understand the emissions and air quality impacts of these relatively understudied sources, especially for oil/gas operations in light of increasing US production. Ground site measurements in Bakersfield and regional aircraft measurements of reactive gas-phase organic compounds and methane were part of the CalNex (California Research at the Nexus of Air Quality and Climate Change) project to determine the sources contributing to regional gas-phase organic carbon emissions. Using a combination of near-source and downwind data, we assess the composition and magnitude of emissions, and provide average source profiles. To examine the spatial distribution of emissions in the San Joaquin Valley, we developed a statistical modeling method using ground-based data and the FLEXPART-WRF transport and meteorological model. We present evidence for large sources of paraffinic hydrocarbons from petroleum operations and oxygenated compounds from dairy (and other cattle) operations. In addition to the small straight-chain alkanes typically associated with petroleum operations, we observed a wide range of branched and cyclic alkanes, most of which have limited previous in situ measurements or characterization in petroleum operation emissions. Observed dairy emissions were dominated by ethanol, methanol, acetic acid, and methane. Dairy operations were responsible for the vast majority of methane emissions in the San Joaquin Valley; observations of methane were well correlated with non-vehicular ethanol, and multiple assessments of the spatial distribution of emissions in the San Joaquin Valley highlight the dominance of dairy operations for methane emissions. The petroleum operations source profile was developed using the composition of non-methane hydrocarbons in unrefined natural gas associated with crude oil. The observed source profile is consistent with fugitive emissions of condensate during storage or processing of associated gas following extraction and methane separation. Aircraft observations of concentration hotspots near oil wells and dairies are consistent with the statistical source footprint determined via our FLEXPART-WRF-based modeling method and ground-based data. We quantitatively compared our observations at Bakersfield to the California Air Resources Board emission inventory and find consistency for relative emission rates of reactive organic gases between the aforementioned sources and motor vehicles in the region. We estimate that petroleum and dairy operations each comprised 22% of anthropogenic non-methane organic carbon at Bakersfield and were each responsible for 8-13% of potential precursors to ozone. Yet, their direct impacts as potential secondary organic aerosol (SOA) precursors were estimated to be minor for the source profiles observed in the San Joaquin Valley
Microservice Transition and its Granularity Problem: A Systematic Mapping Study
Microservices have gained wide recognition and acceptance in software
industries as an emerging architectural style for autonomic, scalable, and more
reliable computing. The transition to microservices has been highly motivated
by the need for better alignment of technical design decisions with improving
value potentials of architectures. Despite microservices' popularity, research
still lacks disciplined understanding of transition and consensus on the
principles and activities underlying "micro-ing" architectures. In this paper,
we report on a systematic mapping study that consolidates various views,
approaches and activities that commonly assist in the transition to
microservices. The study aims to provide a better understanding of the
transition; it also contributes a working definition of the transition and
technical activities underlying it. We term the transition and technical
activities leading to microservice architectures as microservitization. We then
shed light on a fundamental problem of microservitization: microservice
granularity and reasoning about its adaptation as first-class entities. This
study reviews state-of-the-art and -practice related to reasoning about
microservice granularity; it reviews modelling approaches, aspects considered,
guidelines and processes used to reason about microservice granularity. This
study identifies opportunities for future research and development related to
reasoning about microservice granularity.Comment: 36 pages including references, 6 figures, and 3 table
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