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1.
Summary We report on the development of an adaptive optimum filter for processing the data of a resonant bar gravitational-wave detector.
This filter, based on the matched-filter theory, is adaptive in the sense that the function it realizes is derived from the
actual noise spectrum of the data being analysed (instead from an idealized model of the noise). Its implementation is mostly
based on frequency domain techniques. We also report on the application of the new filter to the data of the cryogenic antenna
Explorer of the Rome group, with particular reference to the comparison between its performance and that of an otpimum filter
with fixed values of the parameters. 相似文献
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E. Amaldi E. Coccia C. Cosmelli Y. Ogawa G. Pizzella P. Rapagnani F. Ricci P. Bonifazi M. G. Castellano G. Vannaroni F. Bronzini P. Carelli V. Foglietti G. Cavallari R. Habel I. Modena G. V. Pallottino 《Il Nuovo Cimento C》1984,7(3):338-354
Summary We report on the cooling at liquid-helium temperature of our 2270 kg 5056 Al bar at CERN. The liquid-helium container had
been filled up to 1500 liters ensuring to keep the antenna cold for more than one month. The antenna is equipped with a resonant
capacitive transducer operating at constant electrical charge with a FET low-noise amplifier. The transducer is tuned to the
antenna within less than I Hz and the two normal-mode frequencies are ν−=908.160 Hz and ν+=924.234 Hz with an applied electrical field in the transducer of 106 V/m. The corresponding overall merit factors areQ
−=5.20·106 andQ
+=7.25·106. The transducer has been tested up to an electrical field of 6·106 V/m: in this condition we have βQ≈104. The antenna has been in operation for several weeks giving, for the Brownian noise, values in agreement with the calculated
values. We report also on the results of tests performed on a DC SQUID, whose input was connected to a commercial capacitor
via a transformer with turn ratio of 1000.
Supported in part by Japan Society for the Promotion of Science. 相似文献
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Summary We report on the application of Wiener filters to the data of Weber-type gravitational-wave antennas, with particular reference
to data processed by means of lock-in amplifiers driven at the frequencies of the modes of the detector. After a review of
some basic results concerning the filtering of the data, we briefly examine the relationship between Wiener filters and matched
filters. The discussion that follows is centred on various aspects related to the practical application of Wiener filters
as well as on their limitations, also addressing the dependence of their performance on the values of their parameters. Finally,
we consider some applications of non-optimal Wiener filters: by reducing the filter smoothing time constant, the time resolution
can be increased; by increasing it, the filter becomes an estimator of the Brownian motion. 相似文献
6.
P. Astone M. Bassan R. Bizzarri P. Bonifazi L. Brocco P. Carelli E. Coccia C. Cosmelli A. Degasperis S. Frasca V. Fafone E. Majorana I. Modena G. Modestino A. Moleti G.V. Pallottino G. Pizzella P. Puppo P. Rapagnani F. Ricci R. Terenzi M. Visco 《The European Physical Journal C - Particles and Fields》1998,5(4):651-664
We present an experiment performed to study the behaviour of the dynamic gravitational interaction at laboratory scale. We
used as field generator a mass quadrupole rotating in the range of 460 Hz and we detected the acceleration field with the
cryogenic gravitational wave antenna Explorer of the Rome group. We report the measurements of this interaction as a function
of the distance between the field source and the detector. An upper limit on the parameters of a Yukawa-like potential, modeling
an hypotetic deviation from the Newtonian law of gravity, is derived.
Received: 14 June 1998 / Published online: 16 September 1998 相似文献
7.
Dimitri P. Bertsekas Stefano Pallottino Maria Grazia Scutellà 《Computational Optimization and Applications》1995,4(2):99-125
In this paper we consider strongly polynomial variations of the auction algorithm for the single origin/many destinations shortest path problem. These variations are based on the idea of graph reduction, that is, deleting unnecessary arcs of the graph by using certain bounds naturally obtained in the course of the algorithm. We study the structure of the reduced graph and we exploit this structure to obtain algorithms withO (n min{m, n logn}) andO(n
2) running time. Our computational experiments show that these algorithms outperform their closest competitors on randomly generated dense all destinations problems, and on a broad variety of few destination problems.Research supported by NSF under Grant No. DDM-8903385, by the ARO under Grant DAAL03-86-K-0171, by a CNR-GNIM grant, and by a Fullbright grant 相似文献
8.
E. Amaldi C. Cosmelli P. Bonifazi F. Bordoni V. Ferrari U. Giovanardi G. Vannaroni G. V. Pallottino G. Pizzella I. Modena 《Il Nuovo Cimento C》1978,1(4):341-359
Summary New measurements obtained at the University of Rome by means of a cryogenic gravitational-wave antenna of massM=24.4 kg operated atT=4.5 and 1.5 K are reported. The operation was interrupted after 90 hours of data taking, mainly during successive nights,
although the antenna could continue to function very satisfactorily for a much longer time. The rate of disturbances is so
small that it can be easily eliminated by coincidences with other antennas. The overall effective temperature obtained with
an appropriate data analysis algorithm atT=1.5 K isT
eff∼=0.79 K. This value is mostly due to the noise temperature of the FET preamplifier which constitutes the main limiting factor
to the sensitivity of present gravitational-wave resonant antennas.
Research supported by the Faculty of Natural Sciences of the University of Rome and by the C.N.R. 相似文献
Riassunto Si presentano i risultati di nuove misure eseguite all'Università di Roma con un'antenna gravitazionale criogenica di massaM=24.4 kg funzionante aT=4.5 e 1.5 K. Le misure sono state interrotte dopo 90 ore di raccolta di dati, fatte prevalentemente durante la notte, nonostante che l'antenna potesse continuare a funzionare molto soddisfacentemente per tempi assai più lunghi. La frequenza statistica dei disturbi è tale da poterli facilmente eliminare a mezzo di coincidenze con altre antenne. La temperatura efficace dell'antenna funzionante aT=1.5 K, ottenuta impiegando nell'analisi dei dati un opportuno algoritmo, èT eff=0.79 K. Questo valore è dovuto prevalentemente alla temperatura di rumore di fondo del FET del preamplificatore che costituisce il principale fattore limitante la sensibilità delle attuali antenne risonanti.
Резюме Приводятся результаты новых измерений, проведенных в Римском Университете с помощью антенны гравитационных волн с массойМ=24.4 кг, работающей при низких температурахТ=4.5 и 1.5 К. Действие антенны было прервано после 90 часов работы, хотя антенна могла продолжать фынкционировть очень удовлетворительно более продолжительное время. Интенсивность возмущений является настолько малой, что их влияние может Быть легко исключено посредством совпадений с другими антеннами. Полная эффективная температура, полученная с помощью анализа соответствующих данных приТ=1.5 К, составляетТ эфф=0.79 К. Эта величина, главным образом, обусловлена шумовой температурой FET предусилителя, который представляет основой ограничивающий фактор для чувствитеительности резонансных антенн гравитационных волн.
Research supported by the Faculty of Natural Sciences of the University of Rome and by the C.N.R. 相似文献
9.
E. Amaldi C. Cosmelli S. Frasca I. Modena G. V. Pallottino G. Pizzella F. Ricci P. Bonifazi F. Bordoni V. Ferrari U. Giovanardi V. Iafolla B. Pavan S. Ugazio G. Vannaroni 《Il Nuovo Cimento C》1978,1(6):497-509
Summary The intermediate gravitational-wave antenna ofM=390 kg and ν0=1795 Hz has been operated at 4.2 K in the Laboratorio Plasma Spazio of CNR from June 10 to July 18, 1978. The data collected
during more than 50% of the time show an effective temperature of 1.5 K on the average, with periods of the order of a few
hours during which it goes below 1 K. This corresponds to an instrumental sensitivity of 2 GPU=200 J/m2·Hz. The observed difference between observed and computed equivalent temperature is due to disturbances of mechanical and
thermal origin which we believe can be further reduced.
Riassunto L'antenna gravitazionale intermedia di massaM=390 kg e frequenza ν0=1795 Hz è stata posta e mantenuta in funzione a 4.2 K nel Laboratorio del Plasma nello Spazio del CNR dal 10 Giugno al 18 Luglio 1978. I dati, raccolti per più del 50% del tempo, corrispondono in media ad una temperatura efficace di 1.5 K, con periodi dell'ordine di alcune ore durante i quali essa scende al di sotto di 1 K. Questa corrisponde a una sensibilità strumentale di 2 GPU-200 J/m2·Hz. La differenza fra il valore osservato e quello calcolato della temperatura efficace è dovuto a disturbi di origine meccanica e termica che noi riteniamo di poter ulteriormente ridurre.
Резюме Промежуточная антенна гравитационных волн сM=390 кг и ν0=1795 Гц действовала при 4.2 К в лаборатории плазмы Национального Исследовательского Центра с 10 июня по 18 июля 1978 г. Данные, полученные в течение более 50% времени, указывают эффективную температуру 1.5 К в среднем, с периодами порядка нескольких часов, в течение которЫх эффективная температура опускалась ниже 1 К. Это соответствует инструментальной чувствительности 2 GPU=200 Дж/м2·Гц. Обнаруженная разница между наблюденной и вычисленной эквивалентной температурой обусловлена возмущениями механическиой и тепловой природы, которые, как мы считаем, могут быть в дальнейшем уменьшены.相似文献
10.
G. V. Pallottino 《Il Nuovo Cimento C》1990,13(1):19-33
Summary The author reports on the analysis of the data obtained with the detectors given in the title in the period 12h of February
22, 1987 to 6h of February 23, 1987, that includes the time of the ν observation with the Mont Blanc detector during SN 1987a. A very significant correlation has been observed among the data of the above detectors in a period of one or two hours which
includes the time of the Mont Blanc 5ν observation. The correlation between the g.w. data and the Kamiokande data is found
if a time of 7.8s is added to the Kamioka recorded time; this is very close to the time difference, 6.2s, between the IMB
and Kamioka large ν bursts observed at ≈7h 35 min.
To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee. 相似文献