This paper explores multicarrier waveforms to improve the spectrum efficiency of radar and communication systems that cooperatively coexist in the same bandwidth. We propose two joint design ...paradigms based on sharing and allocation, respectively. The allocation-based design brings in the advantage of interference avoidance and easy implementation, while the sharing-based joint design offers additional gain in spectrum efficiency. For both design paradigms, the communication throughput is maximized under a minimum signal-to-interference-plus-noise ratio (SINR) constraint for the radar along with power constraints. The sharing-based design involves non-convex optimization, which is solved via an alternating direction sequential convex programming (AD-SCP) approach. Meanwhile, the allocation-based design is a mixed integer nonlinear optimization problem, which is solved by the optimum but computationally prohibitive branch and bound algorithm, as well as a suboptimum penalized SCP method. Numerical results show that the proposed joint design paradigms significantly improve the spectrum efficiency over a conventional greedy search based allocation scheme.
A MW 6.3 earthquake struck on April 6, 2009 the Abruzzi region (central Italy) producing vast damage in the L'Aquila town and surroundings. In this paper we present the location and geometry of the ...fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks. The distribution of aftershocks, 712 selected events with ML ≥ 2.3 and 20 with ML ≥ 4.0, defines a complex, 40 km long, NW trending extensional structure. The main shock fault segment extends for 15–18 km and dips at 45° to the SW, between 10 and 2 km depth. The extent of aftershocks coincides with the surface trace of the Paganica fault, a poorly known normal fault that, after the event, has been quoted to accommodate the extension of the area. We observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes.
Skin malignancies of the head and neck inflict significant structural, functional, and cosmetic burdens upon those affected. We retrospectively addressed electrochemotherapy anti-tumour efficacy in ...head and neck skin cancer patients who were not suitable for standard treatments. Scars' physical characteristics and aesthetics were evaluated using validated scar assessment scales. Among 33 treated patients, 82% experienced a complete tumour response while 18% experienced a partial response. At a median time period of 7 months, 96% of the evaluated scars came close to resembling the normal surrounding skin showing excellent results in terms of restoration to original condition with no deformity and/or distortion and in terms of preservation of functionality, such as oral competence and eye protection. Electrochemotherapy is an effective local anticancer procedure for cutaneous tumours. In the treatment of skin malignancies of the head and neck, especially in non-surgical cases, in the elderly and in patients declining surgery, electrochemotherapy may represent a valid alternative to standard management.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We calculate seismic velocity structure of the north Zagros suture zone, west Iran, to resolve the crustal features at the boundary of Arabian‐Central Iranian collision. We compute teleseismic ...receiver functions (RFs) for 46 stations along a transect crossing the suture. Through harmonic analysis and inversion of the RF data, we obtain information on the characteristics of the suture zone at depth. The RFs and their harmonics show a low angle NE dipping boundary between the overriding layer and a midcrustal low velocity zone, which corresponds to the suture zone. The overriding high velocity feature (Vs ~ 3.8 km/s) is interpreted as an intermediate depth crustal complex exhumed close to the surface through imbricate thrust faulting and enhanced by crustal buoyancy due to continental underthrusting. Significant anisotropy is found above and below the suture zone: We interpret it in terms of slow‐symmetry‐axis anisotropy and derive clues on the ongoing deformation processes.
Key Points
We confirmed existence of a weak shear zone in the suture between Arabian plate and the Eurasia in western Zagros
Overriding crust exhumed close to the surface through imbricate thrust faulting and enhanced by crustal buoyancy
Rock foliation and fluid or melt filled fractures formed during the shearing are potential source of anisotropy in both side of the suture
This paper deals with the synthesis of constant modulus waveforms that optimize radar performance while satisfying multiple spectral compatibility constraints. For each shared band, a precise control ...is imposed on the injected interference energy. Furthermore, the compliance with amplifiers operating in saturation is ensured at the design stage where phase-only waveforms are considered. To tackle the resulting NP-hard optimization problem, an iterative procedure based on the coordinate descent method is introduced. The overall computational burden of the algorithm is linear with respect to the code length as well as the number of iterations and less then cubic with reference to the number of spectral constraints. Hence, some case studies are reported to highlight the effectiveness of the technique.
This research considers the linear-FM (LFM) of a noise radar waveform for resolving targets when channel noise and four popular radar sidelobe weighting functions are considered. By using large ...time-bandwidth products and systematically varying the phase scaling factor κ, results from the digital matched filter output provide evidence that the LFM noise waveform 1) has range-Doppler resolution similar to conventional chirp waveforms and 2) has a low probability of intercept (LPI) similar to random noise waveforms. We acquire the results using a computer-based simulation and verify the location of target peaks using the chirp waveform output for both stationary and moving target cases.
Due to the availability of cheap commercial and customizable drones, the potential for using them to carry threat payloads has increased significantly. In this study, radar signatures of drones ...carrying simulated threat payloads have been investigated experimentally. Two different scenarios were considered: 1) drones carrying heavy payloads and 2) the dynamic response of a drone subject to inertial recoil forces which mimic the effect of a firearm attached to the drone. Experimental data for the two scenarios was collected with 24 and 94 GHz Doppler radar systems. Micro-Doppler analysis has revealed that (i) the degree of fluctuation in helicopter rotor modulation (HERM) lines in long integration spectrograms does not correlate with the presence or absence of a heavy payload and (ii) the blade flashes in fully sampled, short integration spectrograms confirm that the tip velocity and rotation rate increase with payload weight as extra thrust is required. However, in both cases, these effects are difficult to attribute exclusively to the presence of the heavy payloads as they can also be attributed to other factors affecting flight dynamics such as wind or platform maneuvers. Finally, we present what we believe to be the first measurements of a simulated recoil scenario in which distinct signatures in the bulk Doppler of the fuselage are clearly attributable to the applied recoil. Analysis shows that these signatures are consistent with the inertial forces which would be imparted by a 9 mm parabellum round fired from a Glock 22 pistol if it was attached to the drone.
Although routinely utilized in literature, orthogonal waveforms may lose orthogonality in distributed multi-input multi-output (MIMO) radar with spatially separated transmit (TX) and receive (RX) ...antennas, as the waveforms may experience distinct delays and Doppler frequency offsets unique to different TX-RX propagation paths. In such cases, the output of each waveform-specific matched filter (MF), employed to unravel the waveforms at the RXs, contains both an auto term and multiple cross terms , i.e., the filtered response of the desired and, respectively, undesired waveforms. We consider the impact of non-orthogonal waveforms and their cross terms on target detection with or without timing, frequency, and phase errors. To this end, we present a general signal model for distributed MIMO radar, examine target detection using existing coherent/non-coherent detectors and two new detectors, including a hybrid detector that requires phase coherence locally but not across distributed antennas, and provide a statistical analysis leading to closed-form expressions of false alarm and detection probabilities for all detectors. Our results show that cross terms can behave like foes or friends , respectively, if they and the auto term add destructively or constructively , depending on the propagation delay, frequency, and phase offsets. Regarding sync errors, we show that phase errors affect only coherent detectors, frequency errors degrade all but the non-coherent detector, while all are impacted by timing errors, which result in a loss in the signal-to-noise ratio (SNR).
Two-dimensional (2-D) spectrum sensing is addressed in the context of a cognitive radar to gather real-time space-frequency electromagnetic awareness. Assuming a sensor equipped with multiple receive ...antennas, a discrete-time sensing signal model formally accounting for multiple snapshots of observations is introduced. Hence, a new signal processing strategy exploiting the inherent block-sparsity of the overall profile is developed to glean a reliable 2-D occupancy awareness. Specifically, the proposed approach resorts to the regularized maximum likelihood estimation paradigm including a term promoting the block-sparsity of the 2-D profile so as to automatically foster this peculiarity in the profile evaluation. Some illustrative examples (both on simulated and measured data) are provided to compare the novel strategy with a relevant counterpart available in the open literature and highlight the effectiveness of the developed approach.
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