Design of cylindrical posts in rectangular waveguide by neural network approach Fedi, G.; Manetti, S.; Pelosi, G. ...
IEEE Antennas and Propagation Society International Symposium. Transmitting Waves of Progress to the Next Millennium. 2000 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (C,
2000, Letnik:
2
Conference Proceeding
Full wave analysis of cylindrical posts in rectangular waveguide for antenna networks is in this paper replaced with a properly trained artificial neural network. The network is able to give an ...accurate description of the post behaviour at a given frequency in real time, whereas the full wave simulator would take several minutes. This will be of great importance in synthesis problem.
MMIC active floating gyrator design and accurate modelling Avitabile, G.; Chellini, B.; Fedi, G. ...
ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems (Cat. No.01CH37196),
2001, Letnik:
1
Conference Proceeding
This paper introduces a novel floating gyrator circuit. The circuit is based on two differential pair stages used as voltage controlled current sources (VCCS). In order to characterize the component, ...an accurate passive model is extracted by means of a technique based on symbolic analysis. A prototype has been designed using the Philips ED02AH PHEMT foundry process to validate the proposed model.
In this paper, a new way to apportion the absorption coefficient (babs) of carbonaceous atmospheric aerosols starting from a multi-wavelength optical analysis is shown. This methodology can ...disentangle and quantify the contribution to total absorption of equivalent black carbon (EBC) emitted by wood burning (EBCWB) and fossil fuel (EBCFF) as well as brown carbon (BrC) due to incomplete combustion. The method uses the information gathered at five different wavelengths in a renewed and upgraded version of the approach usually referred to as Aethalometer model. Moreover, we present the results of an apportionment study of carbonaceous aerosol sources performed in a rural area and in a coastal city, both located in the North-West of Italy. Results obtained by the proposed approach are validated against independent measurements of levoglucosan and radiocarbon. At the rural site the EBCWB and EBCFF relative contributions are about 40% and 60% in winter and 15% and 85% in summer, respectively. At the coastal urban site, EBCWB and EBCFF are about 15% and 85% during fall. The OC contribution to the wood burning source at the rural site results approximately 50% in winter and 10% in summer and about 15% at the coastal urban site in fall. The new methodology also provides a direct measurement of the absorption Ångström exponent of BrC (αBrC) which resulted αBrC = 3.95 ± 0.20.
Display omitted
•Aerosol light absorption at several λs due to Black and Brown Carbon is measured.•The value of Ångström exponent of Brown Carbon is directly extracted by raw data.•The new apportionment procedure disentangles fossil and wood burning contributions.•Equivalent Black Carbon and Organic Carbon are separately apportioned.•The procedure is validated against independent Levoglucosan and 14C determination.
An artificial neural network (ANN) analysis of profiled corrugated circular horns is proposed. This technique allows, on the basis of a reduced number of full-wave analysis, for the supervised ...learning of an ANN able to interpolate accurate results for a large class of horns. The performances in computing time of the ANN are far better than those of the full-wave analysis, and its memory requirements are far lower allowing for the ANN to run on any computer.
Project portfolio management (PPM) is a commonly employed technique to align a project portfolio with strategic goals. Prior research has mainly regarded PPM as a methodology to optimize the overall ...benefit of a project portfolio. While adequate project selection techniques are certainly important, we argue that successful PPM – and consequently effective strategy implementation – depends on an organization's structural alignment with the needs of PPM. Based on three cases in the German construction industry, we study the effects of fundamental strategic changes on the project selection and organizational structure. From our case analysis, we develop a substantive theory to explain how the criteria, used by a company to choose and evaluate its projects, influence the company's structure through the information requirements created by such criteria. To assess whether our theory is in line with accepted schools of thought on organizational design, we integrate it with existing organizational theories. Our contribution is twofold. First, we offer a substantive theory that integrates strategy implementation, organizational information processing, and structural adaptation. Second, we introduce a new antecedent of successful PPM, namely structural alignment, thus introducing a new perspective on PPM beyond mere project selection techniques.
A new symbolic approach for testability measurement of analog networks Catelani, M.; Fedi, G.; Luchetta, A. ...
Proceedings of 8th Mediterranean Electrotechnical Conference on Industrial Applications in Power Systems, Computer Science and Telecommunications (MELECON 96),
1996, Letnik:
1
Conference Proceeding
A new approach for testability measurement of analog networks is presented. It is based on the use of symbolic techniques, that allow us to realize very simple testability evaluation algorithms. The ...new method presents noteworthy advantages from a computational point of view with respect to previous symbolic techniques of testability measurement developed by the authors in the past. In fact it does not require the computation of the sensitivities of the network functions, but it is based only on the study of the network function symbolic coefficients. A new theorem has been proved and the subsequent new algorithm permits to completely eliminate the roundoff errors and increase the computing speed. A brief introduction to the program which implements this new algorithm is also presented.
A new symbolic approach to the fault diagnosis of analog circuits Catelani, M.; Fedi, G.; Giraldi, S. ...
Quality Measurement: The Indispensable Bridge between Theory and Reality (No Measurements? No Science! Joint Conference - 1996: IEEE Instrumentation and Measurement Technology Conference and IMEKO Tec,
1996, Letnik:
2
Conference Proceeding
A new approach for the fault diagnosis of analog circuit is presented. Particular attention is given to the uncertainty propagation in the measurement process in order to locate and identify the ...faulty element causing the failure of the circuit under test. The proposed procedure is based on the use of symbolic techniques which allows to implement a fully automated fault diagnosis system with a strongly reduced computational complexity and an increasing computing speed with respect to a completely numerical approach.
SUMMARY
The separation of the effects of deep-seated sources of potential fields from those of shallower ones is a frequent requirement when interpreting magnetic or gravity fields. A common ...procedure is estimating the regional, long wavelength, component of the field by analysing the data over an area larger than that of the local feature of interest. The local components are found by subtracting the estimated regional from the observed data. These approaches may have difficulties in their application, as the dataset over large areas may not be available and other local anomalies, in the enlarged area, may prevent a reliable estimate of the regional field. We present an alternative and simple approach to the regional-residual separation problem not requiring the analysis over large areas and aiming at estimating the local, rather than the regional, component. Our method exploits the natural enhancement of short wavelengths obtainable by computing vertical derivatives of potential fields. An equivalent layer source is computed from the vertical derivative and is used to estimate the local field. The optimal differentiation order can be determined by inspecting the obtained results. This parameter may assume even fractional values, so that the method results a very versatile tool. The application to a complex synthetic case and two real data examples demonstrates the utility of this approach. In summary, our method has some peculiar characteristics making it an interesting alternative to currently used approaches to regional-residual separation: (i) it is a local method, so it can work well even when processing datasets relative to areas of limited extension; (ii) unlike most current methods, estimating a smooth regional component, our method directly produces an estimate of the local field and (iii) it is highly versatile, as the key parameter, that is the fractional differentiation order, can be finely adjusted up to obtain an optimal local field.
We present a 3D model of the main crustal boundaries beneath the Campanian region and the onshore and offshore surrounding areas, based on high-resolution potential field data. Our main objective is ...the definition of the main structural interfaces in the whole Campanian region from gravity and magnetic data, thanks to their ability to define them on a regional and continuous way. The complex morphology of the Mesozoic carbonate platform, which is fundamental to constrain the top of geothermal reservoir, was reconstructed by inverting the vertical gradient of gravity. We assumed local information from seismic models and boreholes to improve the model. We modeled the deep crustal structures by spectral analysis of Bouguer gravity and magnetic data. The inferred depth estimates indicate a shallow crystalline basement below the Tyrrhenian crust and the Apulian foreland and a significant depression beneath the Bradanic foredeep. The map of the Moho boundary shows a NE-SE verging trough below the Southern Apennine chain and two pronounced uplifts beneath the foreland and the Tyrrhenian crust. We also estimated the depth to the magnetic bottom, showing a thick magnetic crust below the mountain chain and shallow depths where the crustal heat flow is high. The models were compared with seismic sections along selected profiles; a good agreement was observed, despite of some inherent lower resolution for the gravity modelling from spectral methods. The regional covering and the continuity of our estimated crustal interfaces make it a new and valid reference for further geological, geophysical and geothermal studies, especially in areas such as northern and eastern Campania, where there is an incomplete geophysical and geological information.
We analyze a wide gravity low in the Campania Active Volcanic Area and interpret it by a large and deep source distribution of partially molten, low-density material from about 8 to 30 km depth. ...Given the complex spatial-temporal distribution of explosive volcanism in the area, we model the gravity data consistently with several volcanological and petrological constraints. We propose two possible models: one accounts for the coexistence, within the lower/intermediate crust, of large amounts of melts and cumulates besides country rocks. It implies a layered distribution of densities and, thus, a variation with depth of percentages of silicate liquids, cumulates and country rocks. The other reflects a fractal density distribution, based on the scaling exponent estimated from the gravity data. According to this model, the gravity low would be related to a distribution of melt pockets within solid rocks. Both density distributions account for the available volcanological and seismic constraints and can be considered as end-members of possible models compatible with gravity data. Such results agree with the general views about the roots of large areas of ignimbritic volcanism worldwide. Given the prolonged history of magmatism in the Campania area since Pliocene times, we interpret the detected low-density body as a developing batholith.
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