191 research outputs found
Miniature Triple-Mode Dielectric Resonator Filters
In this paper, a new class of triple-mode microwave filters is presented. These devices use the degenerate pair of the HE11ÎŽ mode and the single TM01ÎŽ mode in dielectric-loaded cavities with an unloaded Q-factor of 3000-5000 and reasonable spurious-free window. The proposed structure is obtainable in less than one-quarter of the physical volume of equivalent TEM filters. A finite-element method solver for electromagnetic structures (HFSS) is used to study the main properties of this resonator. Fundamental design rules for triple-mode bandpass filters with controllable finite transmission zeros are presented. Design examples of bandpass filters with finite transmission zeros on the high or low or both sides of the passband are demonstrated. Measured results demonstrate excellent performance
From environmental information systems to social networks: fostering co-operation in the ETH-UNS Case Study for sustainable regional development
Abstract The ETH-UNS Case Study is part of the master program in Environmental Sciences. It is a hybrid combining teaching, research, and application. Joint problem solving between science and society is a major principle of our work. In our view, such approaches are a prerequisite in developing strategies towards a sustainable society. However, this requires improved organization of knowledge, co-operation of work and communication among all people involved. Co-operation and communication is needed at least (a) within and between the different study teams, (b) between the study teams and local agents and (c) among local agents with a view to sustain local social networks. Since its beginning in 1994, the ETH-UNS Case Study has used a broad set of IT-tools to support co-ordination, communication and co-operation of work. Starting form a incomplete peer-to-peer system, we advanced to a centralized file sharing system, and are now embarking into an integrated, dynamic network approach. A new web-based information system, named «living document», will be updated and supplemented continuously. The «living document» will support group work, communication among participants from inside and outside university and co-ordination of activities
The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements
International audienceWithin the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7â418 nm and the visible from 400â652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively) from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3, and NO2), the measured solar spectra are compared with previous observations. Our solar irradiance is +1.6% larger than the re-calibrated Kurucz et al. (1984) solar spectrum (Fontenla et al., 1999, called MODTRAN 3.5) in the visible spectral range (435â650 nm), +1.5% larger in the (370â415 nm) wavelength interval, but -4% smaller in the UV spectral range (316.7â370 nm), when the Kurucz spectrum is convolved to the spectral resolution of our instrument. The same comparison with the SOLSPEC solar spectrum (Thuillier et al., 1997, 1998a, b) confirms the somewhat larger solar irradiance (+1.7%) measured by the balloon instrument from 435â500 nm, but not from 500â650 nm, where the SOLSPEC is -1.3% lower than MODTRAN 3.5. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (â re-calibrated by the University of Bremen â) with MODTRAN 3.5 indicates an agreement of +0.2% in the visible spectral range (435â585 nm). With this calibration, the SCIAMACHY solar spectrum is congruent with the balloon observations (-1%) in the 316.7â370 nm wavelength range, but both are up to -5%/-3% smaller than MODTRAN 3.5 and SOLSPEC, respectively. In agreement with findings of Skupin et al. (2002) our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements
Public transit route mapping for large-scale multimodal networks
ABSTRACT: For the simulation of public transport, next to a schedule, knowledge of the public transport routes is required. While the schedules are becoming available, the precise network routes often remain unknown and must be reconstructed. For large-scale networks, however, a manual reconstruction becomes unfeasible. This paper presents a route reconstruction algorithm, which requires only the sequence and positions of the public transport stops and the street network. It uses an abstract graph to calculate the least-cost path from a route's first to its last stop, with the constraint that the path must contain a so-called link candidate for every stop of the route's stop sequence. The proposed algorithm is implemented explicitly for large-scale, real life networks. The algorithm is able to handle multiple lines and modes, to combine them at the same stop location (e.g., train and bus lines coming together at a train station), to automatically reconstruct missing links in the network, and to provide intelligent and efficient feedback if apparent errors occur. GPS or OSM tracks of the lines can be used to improve results, if available. The open-source algorithm has been tested for Zurich for mapping accuracy. In summary, the new algorithm and its MATSim-based implementation is a powerful, tested tool to reconstruct public transport network routes for large-scale systems
Photonuclear Reactions of Three-Nucleon Systems
We discuss the available data for the differential and the total cross
section for the photodisintegration of He and H and the corresponding
inverse reactions below MeV by comparing with our calculations
using realistic interactions. The theoretical results agree within the
errorbars with the data for the total cross sections. Excellent agreement is
achieved for the angular distribution in case of He, whereas for H a
discrepancy between theory and experiment is found.Comment: 11 pages (twocolumn), 12 postscript figures included, uses psfig,
RevTe
Large Chinese land carbon sink estimated from atmospheric carbon dioxide data
Limiting the rise in global mean temperatures relies on reducing carbon dioxide (CO2) emissions and on the removal of CO2 by land carbon sinks. China is currently the single largest emitter of CO2, responsible for approximately 27 per cent (2.67 petagrams of carbon per year) of global fossil fuel emissions in 20171. Understanding of Chinese land biosphere fluxes has been hampered by sparse data coverage2â4, which has resulted in a wide range of a posteriori estimates of flux. Here we present recently available data on the atmospheric mole fraction of CO2, measured from six sites across China during 2009 to 2016. Using these data, we estimate a mean Chinese land biosphere sink of â1.11 ± 0.38 petagrams of carbon per year during 2010 to 2016, equivalent to about 45 per cent of our estimate of annual Chinese anthropogenic emissions over that period. Our estimate reflects a previously underestimated land carbon sink over southwest China (Yunnan, Guizhou and Guangxi provinces) throughout the year, and over northeast China (especially Heilongjiang and Jilin provinces) during summer months. These provinces have established a pattern of rapid afforestation of progressively larger regions5,6, with provincial forest areas increasing by between 0.04 million and 0.44 million hectares per year over the past 10 to 15 years. These large-scale changes reflect the expansion of fast-growing plantation forests that contribute to timber exports and the domestic production of paper7. Space-borne observations of vegetation greenness show a large increase with time over this study period, supporting the timing and increase in the land carbon sink over these afforestation regions
Dynamic Searchable Encryption with Access Control
We present a searchable encryption scheme for dynamic document collections in a multi-user scenario. Our scheme features fine-grained access control to search results, as well as access control to operations such as adding documents to the document
collection, or changing individual documents. The scheme features verifiability of search results. Our scheme also satisfies the forward privacy notion crucial for the security of dynamic searchable encryption schemes
Compact broadband frequency selective microstrip antenna and its application to indoor positioning systems for wireless networks
This study presents a low-profile broadband microstrip patch antenna with filtering response. The proposed antenna consists of a rectangular patch and four parasitic gap-coupled elements, two L- and two rectangular-shaped patches. A broadband quasi-elliptic boresight gain response is obtained without using any extra filtering circuits. The input impedance of each radiating element, i.e., driven patch and parasitic elements, is matched to its radiating quality factor and the couplings between patches are optimised for broadband impedance bandwidth with filtering response. Prototype hardware is designed and fabricated on Kappa 438 substrate with a relative permittivity of 4.4 and thickness of 3.2 mm. The antenna exhibits a total size of 25 Ă 23 Ă 3.2 mm 3 with relative impedance bandwidth (voltage standing wave ratio<;2) of 60% ranging from 4.4 to 7.8 GHz. The experimental results demonstrate good performance with nearly flat gain and good filtering response. The proposed filtering antenna exhibits low pulse distortion in time domain which makes it a good candidate for location-aware Internet-of-things applications employing the IEEE 802.15.4 ultra-wideband standard. Switchable sector base-station antenna system is studied to demonstrate the capability of this design to enhance the localisation and communication performance of the wireless network
The ACOS CO_2 retrieval algorithm â Part 1: Description and validation against synthetic observations
This work describes the NASA Atmospheric CO_2 Observations from Space (ACOS) X_(CO_2) retrieval algorithm, and its performance on highly realistic, simulated observations. These tests, restricted to observations over land, are used to evaluate retrieval errors in the face of realistic clouds and aerosols, polarized non-Lambertian surfaces, imperfect meteorology, and uncorrelated instrument noise. We find that post-retrieval filters are essential to eliminate the poorest retrievals, which arise primarily due to imperfect cloud screening. The remaining retrievals have RMS errors of approximately 1 ppm. Modeled instrument noise, based on the Greenhouse Gases Observing SATellite (GOSAT) in-flight performance, accounts for less than half the total error in these retrievals. A small fraction of unfiltered clouds, particularly thin cirrus, lead to a small positive bias of ~0.3 ppm. Overall, systematic errors due to imperfect characterization of clouds and aerosols dominate the error budget, while errors due to other simplifying assumptions, in particular those related to the prior meteorological fields, appear small
Emergence of qualia from brain activity or from an interaction of proto-consciousness with the brain: which one is the weirder? Available evidence and a research agenda
This contribution to the science of consciousness aims at comparing how two different theories can
explain the emergence of different qualia experiences, meta-awareness, meta-cognition, the placebo
effect, out-of-body experiences, cognitive therapy and meditation-induced brain changes, etc.
The first theory postulates that qualia experiences derive from specific neural patterns, the second
one, that qualia experiences derive from the interaction of a proto-consciousness with the brain\u2019s
neural activity. From this comparison it will be possible to judge which one seems to better explain
the different qualia experiences and to offer a more promising research agenda
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