1,721,433 research outputs found
Portfolio Selection with Minimum Transaction Lots: an Approach with Dual Expected Utility
No full textLE MODIFICAZIONI DELLE VIE AEREE-DIGESTIVE DOPO CHIRURGIA PARZIALE E SUB-TOTALE DELLA LARINGE.
No full textExploiting polarimetric diversity in passive radar
No full textRadar polarimetry has been widely used in radar systems aiming at the detection,
discrimination, and recognition of targets of interest among other interfering sources.
It becomes an essential tool in challenging radar scenarios where the achievable
performance is not under control of the radar designer. This is certainly the case of
passive radar whose performance largely varies with the radiative properties of the
transmitter of opportunity as well as with the severity of the electromagnetic (EM)
scenario that typically includes many interfering sources.
Passive radar, also known as passive coherent location (PCL), technology has
been attracting significant research interest over the past two decades. The
wide interest received by PCL sensors allowed them to increasingly reach a point of
maturity. Nevertheless, by relying on signals emitted by illuminators of opportunity
(IOs) to detect and localize targets, the performance of PCL sensors might be largely
time-varying
and leading to an unreliable surveillance system. The main limitations
stem from the lack of control over the exploited waveform structure as well as from
the strong direct signal and multipath contributions. In addition, significant
interference can be experienced due to co-channel
or adjacent-channel
transmissions,
especially when broadcast emitters are exploited as IOs.
Recently, among the advanced processing strategies devised to overcome these
limitations, the exploitation of polarization diversity has been considered as a mean
to increase the reliability of passive radar with particular reference to the target
detection task. Specifically, the availability of multi-polarimetric
channels
on receive has been demonstrated to provide robustness against the target echo fading
that results from the induced variable polarization. Moreover, a
proper combination of signals received via differently polarized antennas has been
shown to improve the target identification capability against the interfering sources,
thanks to the wave polarization diversity.
In this chapter, we take this perspective and illustrate practical multi-polarimetric
passive radar architectures together with the corresponding signal processing techniques.
Different approaches are compared both in terms of achievable performance
and based on considerations regarding the resulting system complexity. The aim is to
offer the interested reader with an overview of existing solutions and to provide hints
for the identification of the most suitable architecture for the application at hand.
The discussion is supported by results from real-world
tests performed by means of
experimental passive radar receivers operating at different frequency bands
Portfolio Selection: a Linear Approach with Dual Expected Utility
No full textThis paper analyses the portfolio selection problem under the non-expected tility theory. We assume that the decision maker ranks the alternatives by using a specific dual expected utility. This function allows returns which are less than or
equal to a fixed benchmark to be weighted in a different way from those greater than the fixed benchmark. In this model the implicit risk measure is more general than the standard deviation and it coincides with the downside risk only due to the appropriate choices of the parameters. Under normally distributed returns and appropriate choices of the benchmark, the approach suggested is equivalent to the Markowitz model in term of efficient frontier and moreover has the advantage of using linear programming to obtain the optimal portfolio. It can thus handle high dimensional problems.
We also show results obtained by implementing the model on the Italian stock market
Joint near-lossless compression and watermarking of still images for authentication and tamper localization
No full textA system is presented to jointly achieve imagewatermarking and compression. The watermark is a fragile one being intended for authentication purposes. The watermarked and compressed images are fully compliant with the JPEG-LS standard, the only price to pay being a slight reduction of compression efficiency and an additional distortion that can be anyway tuned to grant a maximum preset error. Watermark detection is possible both in the compressed and in the pixel domain, thus increasing the flexibility and usability of the system. The system is expressly designed to be used in remote sensing and telemedicine applications, hence we designed it in such a way that the maximum compression and watermarking error can be strictly controlled (near-losslesscompression and watermarking). Experimental results show the ability of the system to detect tampering and to limit the peak error between the original and the processed images
PM and PM-Less Motors for Electric Vehicles: A Comparative Analysis
No full textThe automotive industry is focusing on developing more efficient and sustainable powertrains in response to the increasing demand for electric vehicles. The benefits and draw-backs of using alternative motor designs, along with the growing trend among motor manufacturers to reduce their reliance on Permanent Magnets are explored by the authors. The analysis includes electromagnetic studies aimed at identifying the operational limits of each type of motor. Specifically, the comparison involves an Interior Permanent Magnet motor, which utilizes NdFeB magnets, and various permanent magnet less motor designs, such as the Electrically Excited Synchronous Motor, the Hybrid Excited Permanent Magnet motor, the Reluctance motor, and the Permanent Magnet assisted Reluctance motor
Multi‐carrier and multi‐polarimetric model based adaptive target detector for passive radar systems
Full text linkAbstract A new adaptive detection strategy for passive radar systems that fruitfully capitalizes on signals, simultaneously emitted by the same transmitter of opportunity at different carrier frequencies and collected by a set of differently polarized surveillance antennas is derived. Based on recent results that demonstrated the benefits provided by proper strategies to exploit polarimetric diversity, the authors aim at further improving the target detection performance by combining polarimetric and frequency diversity. Real data collected through an FM radio‐based passive radar prototype is used to extensively demonstrate the effectiveness of the derived strategy with respect to state‐of‐the‐art approaches. The conceived solution is proved to successfully enhance the capability to discriminate targets, thanks to an effective disturbance rejection performed at each frequency channel as well as a target echo enhancement and an increased robustness to the time‐varying characteristics of the exploited source of opportunity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
