111,925 research outputs found
Gizero: New Facility for Gravitational Experiments in Free Fall
No full textAbstract - A technique for creating microgravity conditions during free fall (GIZERO project) is described. GIZERO consists
of a vacuum capsule released from balloon altitude (40 km) which is used to shield a payload with an experimental
apparatus free falling inside. The expected residual acceleration is 10^−12 g/√Hz for about 20–25 seconds (50–60 seconds with a propelled capsule).
The GIZERO facility provides opportunities for accurate experiments in gravitational physics. Among others, two
experiments of our particular interest are: testing and calibration of a high sensitivity gravity gradiometer and a test
of the Equivalence Principle (the gravity level can be reduced down to 10^−15 g/√Hz using cryogenic techniques). It
is expected that a triaxial gravity gradiometer prepared for a future space mission can be tested at the sensitivity
level of 10^−2 E/√Hz. The estimated accuracy in testing the Equivalence Principle is 5x10^−14
at the liquid nitrogen
temperature of 77 K and 5x10^−15
at the liquid helium temperature of 4 K. This is the intermediate accuracy between
ground-based and expected space experiments.
The results of design and experimental study of a prototype of the gravity gradiometer are reported
Waste Dynamics, Country Heterogeneity and European Environmental Policy Effectiveness
No full textWe empirically test delinking of waste dynamics with regard to economic growth and the effectiveness of environmental and specific waste-related policies, by exploiting a newly constructed, integrated waste-economic-policy dataset based on official data for the EU15 for 1995-2007. We find that absolute delinking is far from being achieved in the EU despite fairly stringent and longstanding policy commitment that goes back to the mid 1990s, but which however is biased towards waste management and waste disposal rather than waste prevention. Policy as well as country structural factors seem to impact on landfill diversion. Nevertheless, country heterogeneity matters: SURE based analyses show that EU average figures often hide high variance. Their results provide food for thought for a new EU waste policy strategy aimed mainly at landfill diversion and delinking, within a framework strongly oriented to allowing countries to decide about the implementation of EU directives
Rifiuti generati, rifiuti in discarica ed efficacia delle politiche ambientali in Europa
No full textSi presentano varie analisi empiriche sul disaccoppiamento tra dinamiche di generazione e conferimento in discarica dei rifiuti e crescita economica, integrate da disamine sulla efficacia delle politiche ambientali europee, utilizzando un dataset originale che integra fonti EUROSTAT con indicatori di policy nel periodo 1995-2007 per l’Europa a 15. Si riscontra un delinking assoluto, con vari effetti che mostrano l’efficacia delle politiche introdotte in Europa da metà anni novanta, per il conferimento in discarica, ma non per la generazione dei rifiuti, associata ad una elasticità rispetto al reddito in calo, ma ancora positiva. Le politiche come da attese non hanno avuto effetti sull’obiettivo di riduzione della generazione dei rifiuti, che ancora cresce e crescerà nei prossimi anni. La densità di popolazione è un fattore strutturale che appare ridurre sia generazione sia conferimento in discarica. Tuttavia, come da attese, l’eterogeneità tra paesi gioca un ruolo importante. Modelli panel SURE evidenziano come le regolarità statistiche medie europee nascondano spesso specificità che consentono di raggruppare i paesi in base alle diverse performance sulla relazione rifiuti-crescita economica, mettendo anche in luce il rischio di recoupling. Le analisi empiriche panel con fini di analisi ex post delle politiche mostrano di poter avere una forte rilevanza nel supporto alla implementazione e modulazione nazionale delle future politiche sui rifiuti in Europa.Curve di Kuznets, produzione di rifiuti, disaccoppiamento, discariche dei rifiuti
Methodology and Instrumentation for Testing the Weak Equivalence Principle in Stratospheric Free fall
No full textAbstract - The use of the GiZero free-fall facility for testing the weak equivalence principle is discussed in this article. GiZero consists of a vacuum capsule, released from a balloon at an altitude of 40 km, which shields an experimental apparatus free falling inside the capsule itself. The expected residual acceleration external to the detector is 10^-12 g (with g the Earth’s gravitational acceleration) for the 30 s free fall. A common-mode rejection factor of about 10^-4 reduces the residual noise differential output to only 10^-16 g. The gravity detector is a differential accelerometer with two test masses with coincident center of masses (i.e., zero baseline) with capacitive pick ups. Preparatory experiments have been conducted in the laboratory with a precursor detector by measuring controlled gravity signals, at low frequency, and by observing the Luni-Solar tides. The estimated accuracy in testing the weak equivalence principle, with a 95% confidence level, is 5×10^-15 in a 30 s free fall. When compared to orbital free-fall experiments, the GiZero experiment can be considered as a valid compromise which is able to satisfy the requirement for improving significantly the experimental accuracy in testing the equivalence principle with a substantial lower cost, the ability to recover the detector and to repeat the experiment at relatively short time intervals. © 1998 American Institute of Physics
Deep Sea Gravity Measurements: GEOSTAR-2 Mission Results
No full textA new concept gravity meter with sensitivity close to Hz ms / 10 2 8 − − in the range of 10 -5 −1Hz intended for observation of the vertical component of the Earth gravity and
teleseismic waves was implemented at the Istituto di Fisica dello Spazio Interplanetario
(IFSI), CNR and successfully operated during the GEOSTAR-2 mission. The gravimeter has
demonstrated a capability to operate for long time in an autonomous regime and a good
reliability for operation in extreme environments; at the same time the experimental
measurements gave the information for the further gravimeter’s implementation. Results of
observation and data analysis included the registration of seismic waves excited by global
earthquakes and the evaluation of the low frequency modes of free oscillations of the Earth
are reported.JCR Journalope
Deep Sea Gravity Measurements: GEOSTAR-2 Mission Results
No full textA new concept gravity meter with sensitivity close to Hz ms / 10 2 8 − − in the range of 10 -5 −1Hz intended for observation of the vertical component of the Earth gravity and
teleseismic waves was implemented at the Istituto di Fisica dello Spazio Interplanetario
(IFSI), CNR and successfully operated during the GEOSTAR-2 mission. The gravimeter has
demonstrated a capability to operate for long time in an autonomous regime and a good
reliability for operation in extreme environments; at the same time the experimental
measurements gave the information for the further gravimeter’s implementation. Results of
observation and data analysis included the registration of seismic waves excited by global
earthquakes and the evaluation of the low frequency modes of free oscillations of the Earth
are reported.JCR Journalope
Testing deviations from the inverse square law with a freely falling gravity gradiometer at Balloon altitudes
No full textWe discuss a null experiment to search for the fifth force at ranges around 10 km. It is proposed to use a three-axis gravity gradiometer to measure the trace of the Earth gravity tensor from a freely falling elevator dropped by a balloon. The main error sources are considered to some extent
Seismic Noise Rejection System for a Rise-and-Fall Absolute Gravimeter
No full textThe gravimetric prospections are usually performed by using relative instrumentations, having suitable features to work outside a lab or on a vehicle/ship. Nevertheless their relative measures have to be referred to an absolute measure which represents the reference point. These last measurements are not easy to perform due to the difficulty to operate in open field with an absolute-gravimeter. The measurements should be done by using a field-portable instrument able to maintain the high level of precision required to an absolute-gravimeter.
In this work we describe the state of the art in the improvements to the portable Absolute-Gravimeters (AGs), focusing on the possibility to measure and remove the seismic noise which acts on its reference frame. These measurements are done with a special accelerometer embedded in the AG. To process and record data from the AG and from the accelerometer, will be used a Field Programmable Gate Array (FPGA) which, permits an high level of integration of the system and to customize the electronic systems with just minor hardware designs
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