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Frid V.,Sami Shamoon College of Engineering | Sharabi I.,Tel Aviv University | Frid M.,Ben - Gurion University of the Negev | Averbakh A.,Isotop Ltd
Environmental Earth Sciences | Year: 2017

Landfill site is an intensely heterogeneous medium, in which application of 2-D geophysical techniques frequently does not enable its accurate examination due to the lack of correlation between different geophysical profiles. The study was aimed to eliminate such difficulty. Hereafter, the leachate detection methodology is presented including 2-D smoothness-constrained inversion of geoelectrical raw data collected in situ, the inverted data normalization and statistical examination. To eradicate influence of high heterogeneity of the landfill body, the generalized statistical model of the entire site was created including the likelihood analysis of the entire normalized data set. Three geoelectrical parameters were involved in the analysis: inversed electrical resistivity, inversed chargeability (IP) and the ratio of inversed chargeability-to-inversed electrical resistivity (IP/Res). The study was combined with the synthetic modeling, the analysis of bulk versus fluid electrical resistivity relationship and test borehole drillings. Such generalized analysis ensures independency of the results from the locality of sampling/measurements. It was shown that leachate detection can be correctly performed utilizing the IP/Res ratio while the anomaly’s likelihood is higher than 90%. © 2017, Springer-Verlag Berlin Heidelberg.


Frid V.,Isotop Ltd | Averbach A.,Isotop Ltd | Frid M.,RENA | Dudkinski D.,Isotop Ltd | Liskevich G.,Isotop Ltd
Pure and Applied Geophysics | Year: 2017

Geophysical prospecting of underground caves being performed on a construction site is often still a challenging procedure. Estimation of a likelihood level of an anomaly found is frequently a mandatory requirement of a project principal due to necessity of risk/safety assessment. However, the methodology of such estimation is not hitherto developed. Aiming to put forward such a methodology the present study (being performed as a part of an underground caves mapping prior to the land development on the site area) consisted of application of electrical resistivity tomography (ERT) together with statistical analysis utilized for the likelihood assessment of underground anomalies located. The methodology was first verified via a synthetic modeling technique and applied to the in situ collected ERT data and then crossed referenced with intrusive investigations (excavation and drilling) for the data verification. The drilling/excavation results showed that the proper discovering of underground caves can be done if anomaly probability level is not lower than 90 %. Such a probability value was shown to be consistent with the modeling results. More than 30 underground cavities were discovered on the site utilizing the methodology. © 2015, Springer Basel.


Grant
Agency: European Commission | Branch: FP7 | Program: MC-IAPP | Phase: FP7-PEOPLE-2011-IAPP | Award Amount: 1.78M | Year: 2012

The aim of the project is to enhance the potential and output of vibrating machines and decrease their ecological footprint by implementation of parametric resonance (PR). Compared with the regular resonance, the PR is characterized by a much higher intensity within a wide range of frequencies. The advantage of a PR-based machine was demonstrated with a prototype PR screener (PRS) developed and produced by the project partners. The PRS demonstrated large amplitudes of high-frequency lateral oscillations and self-vibro-insulation and could process a naturally wet fine granular material. However, the PR is instable, and its use as an effective operating mode assumes, among others, creation of a stabilized instability regime. This is an inspiring and challenging high-tech task for combined efforts of applied mathematicians and engineers. The extraordinary PR features together with open nontrivial theoretical and engineering problems provide a motivation to undertake this interdisciplinary research. The main objectives are: to develop a technically sound control of PR amplitude; to develop mathematical models for the process of material separation with a PRS; to design PRS-related screens with given stiffness and minimal bending stresses, and to design other types of PR-based separators and crushers. The enhancement of vibro-cutting/drilling tools via the development of the underpinning theory and application of the PR principle will also be an objective. An exchange of fundamentals and technical concepts between the large-scale research and the micro/nano PR studies is assumed. The project activities will be based on close cooperation and targeted secondments between academia and industry. As a result, a large number of ESRs will have a unique opportunity to be trained through research, working on all interdisciplinary aspects, starting from the conceptual design and modelling and finishing with prototypes/demonstrators of new PR-based machines and tools.


Itkis S.E.,Ben - Gurion University of the Negev | Frid V.,Isotop LTD | Sokolova T.B.,Moscow State University
Near Surface Geoscience 2012 | Year: 2012

Geophysical studies included detailed magnetic prospecting and Electrical Resistivity Tomography(ERT) survey were performed for revealing and tracing near-surface archaeological remains in Tel 'En Gev. Since the surveyed areas are located in close vicinity of kibbutz 'En Gev living areas, desired magnetic signal is strongly affected by artificial and environmental disturbances. This complicates magnetic data interpretation. The ERT results free of such influences successfully supplement the magnetic data and allowed us to clear up the sources of the magnetic anomalies and evaluate their size and depth.


Frid V.,Isotop Ltd. | Goldbaum J.,Technological College | Rabinovitch A.,Ben - Gurion University of the Negev | Bahat D.,Ben - Gurion University of the Negev
Philosophical Magazine | Year: 2011

New time-dependent Benioff strain (TDBS) release diagrams were analyzed for acoustic emission during various loading tests and for electromagnetic (EM) radiation emanating during compression and, tension, which end in failure. TDBS diagrams are Benioff diagrams that are built consecutively, each time using a greater number of events (acoustic or EM emissions) using the last event as if it were associated with the 'actual failure'. An examination of such TDBS diagrams shows that at a certain time point (this time point is denoted by the term 'alarm' time), a comparatively short interval prior to actual collapse, their decreasing part is broken by a positive 'bulge'. This 'bulge' is quantified and an algorithm proposed for its assessment. Using the alarm time and other parameters of the failure process (fall, bulge size and escalation factors, bulge slope and slope fall time), a criterion for estimating the time of the actual collapse is developed and shown to agree well with laboratory experimental results. © 2011 Taylor & Francis.


Frid V.,Isotop Ltd | Doudkinski D.,Isotop Ltd | Liskevich G.,Isotop Ltd | Shafran E.,Isotop Ltd | And 3 more authors.
Environmental Earth Sciences | Year: 2010

This paper deals with the integration of electrical resistivity tomography and geochemical methods for studying four different fire-prone landfills. Landfill gas composition (CH4, H2S, O2, CO, CO2) and subsurface temperature were measured with the constant net 50 × 50 m from the depth 10-60 cm. 28 electrical resistivity tomography lines were surveyed, while Wenner and Sclumberger electrode arrays were employed for all measurements. At the studied sites the landfill gas and temperature measurements mapped gas and temperature anomalies over underground fire sources. 2D electrical resistivity tomography lines, performed over these anomalies, showed these fire sources as high-resistivity zones. The joint employment of the electrical imaging and geochemical survey seems to be a useful tool in carrying out diagnostic investigations at fire-prone landfills. © 2009 Springer-Verlag.

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