A Fuzzy Guidance System for Rendezvous and Pursuit of Moving Targets

This article presents the development of a fuzzy guidance system (FGS) for unmanned aerial vehicles capable of pursuing and performing rendezvous with static and mobile targets. The system is designed to allow the vehicle to approach a maneuvering target from a desired direction of arrival and to terminate the rendezvous at a constant distance from the target. In order to perform a rendezvous with a maneuvering target, the desired direction of arrival is adjusted over time to always approach the target from behind, so that the aircraft and target velocity vectors become aligned. The proposed guidance system assumes the presence of an autopilot and uses a set of Takagi–Sugeno fuzzy controllers to generate the orientation and speed references for the velocity and heading control loops, given the relative position and velocity between the aircraft and the target. The FGS treats the target as a mobile waypoint in a 4-D space (position in 2-dimensions, desired crossing heading and speed) and guides the aircraft on suitable trajectories towards the target. Only when the vehicle is close enough to the rendezvous point, the guidance law is complemented with an additional linear controller to manage the terminal formation keeping phase. The capabilities of the proposed rendezvous-FGS are verified in simulation on both maneuvering and non-maneuvering targets. Finally, experimental results using a multi-rotor aerial system are presented for both fixed and accelerating targets

Development of a Hybrid Simulator for Underwater Vehicles with Manipulators

This article describes a hybrid simulation approach meant to facilitate the realization of a simulator for underwater vehicles with one or more manipulators capable of simulating the interaction of the vehicle with objects and structures of the environment. The hybrid simulation approach is first described and motivated analytically, then an analysis of simulation accuracy is proposed, where, in particular, the implications of added mass simulation are discussed. Then, a possible implementation of the proposed architecture is shown, where a robotic simulator of articulated bodies, capable of stable and accurate simulation of contact forces, although unfit to simulate any serious hydrodynamic model, is tightly interfaced with a general purpose dynamic systems simulator that is used to simulate the hydrodynamic forces, the vehicle guidance, navigation, and control system, and also a man-machine interface. Software details and the technicalities needed to interface the two simulators are also briefly presented. Finally, the results of the simulation of three operational scenarios are proposed as qualitative assessment of the simulator capabilities

Molecular characterization of ‘Candidatus Phytoplasma prunorum’ in Cacopsilla pruni insect vector

Recent investigations on molecular characterization of the ‘Candidatus Phytoplasma prunorum’ (16SrX-B subgroup), causal agent of the European Stone Fruit Yellows (ESFY) syndrome, on the non ribosomal tuf gene resulted in the finding of two groups of isolates, named ‘type a’ and ‘type b’, both with a distinctive geographical distribution in Italian stone fruit growing areas (Ferretti et al., 2007 and 2008). Considering the role of Cacopsylla pruni (Scopoli) in the epidemiological cycle of the disease, the presence of the two groups of isolates has also been investigated in infected psyllid individuals from different Italian areas. Both types have been identified in C. pruni specimens collected on apricot, plum and wild Prunus species, confirming the geographical distribution and the percentages of spread of the two isolates.Keywords: ESFY, phytoplasma, characterization, tuf gene, insect vecto

A novel framework for closed-loop robotic motion simulation - Part II: motion cueing design and experimental validation

This paper, divided in two Parts, considers the problem of realizing a 6-DOF closed-loop motion simulator by exploiting an anthropomorphic serial manipulator as motion platform. After having proposed a suitable inverse kinematics scheme in Part I [1], we address here the other key issue, i.e., devising a motion cueing algorithm tailored to the specific robot motion envelope. An extension of the well-known classical washout filter designed in cylindrical coordinates will provide an effective solution to this problem. The paper will then present a thorough experimental evaluation of the overall architecture (inverse kinematics + motion cueing) on the chosen scenario: closed-loop simulation of a Formula 1 racing car. This will prove the feasibility of our approach in fully exploiting the robot motion capabilities as a motion simulator

Identification of a novel plasmid lineage associated with the dissemination of metallo-β-lactamase genes among pseudomonads

Acquisition of metallo-\u3b2-lactamases (MBLs) represents one of most relevant resistance mechanisms to all \u3b2-lactams, including carbapenems, ceftolozane and available \u3b2-lactamase inhibitors, in Pseudomonas spp. VIM-type enzymes are the most common acquired MBLs in Pseudomonas aeruginosa and, to a lesser extent, in other Pseudomonas species. Little is known about the acquisition dynamics of these determinants, that are usually carried on integrons embedded into chromosomal mobile genetic elements. To date, few MBL-encoding plasmids have been described in Pseudomonas spp., and their diversity and role in the dissemination of these MBLs remains largely unknown. Here we report on the genetic features of the VIM-1encoding plasmid pMOS94 from P. mosselii AM/94, the earliest known VIM-1-producing strain, and of related elements involved in dissemination of MBL. Results of plasmid DNA sequencing showed that pMOS94 had a modular organization, consisting of backbone modules associated with replication, transfer and antibiotic resistance. Plasmid pMOS94, although not typable according to the PBRT scheme, was classifiable either in MOBF11 or MPFT plasmid families. The resistance region included the class I integron In70, carrying blaVIM-1, in turn embedded in a defective Tn402-like transposon. Comparison with pMOS94-like elements led to the identification of a defined plasmid lineage circulating in different Pseudomonas spp. of clinical and environmental origin and spreading different MBL-encoding genes, including blaIMP-63, blaBIM, and blaVIM-type determinants. Genetic analysis revealed that this plasmid lineage likely shared a common ancestor and had evolved through the acquisition and recombination of different mobile elements, including the MBL-encoding transposons. Our findings provide new insights about the genetic diversity of MBL-encoding plasmids circulating among Pseudomonas spp., potentially useful for molecular epidemiology purposes, and revealed the existence and persistence of a successful plasmid lineage over a wide spatio-temporal interval, spanning over five different countries among two continents and over 20-years

Detection and distribution of European stone fruit yellows (ESFY) in apricot cv. ‘Bergeron’ and epidemiological studies in the province of Trento (Italy)

The aim was to investigate the performance of ‘Bergeron’ on ‘Wavit’ in 4 experimental fields, in the province of Trento (Italy), where European stone fruit yellows (ESFY) caused by “Candidatus Phytoplasma prunorum” has been constantly spreading since 2000.This included visual inspections for typical symptoms (early bud-break during dormancy and premature leaf-roll) and a highly sensitive Real time-PCR (Rt-PCR) assay. 25 % of the propagation material was checked with this method and found to be healthy, before planting in 2005.The epidemiology of the disease was also studied by focusing on: the presence of the vector Cacopsylla pruni (Scopoli) on conifers, the detection of “Ca. P. prunorum” in psyllid eggs and the transmission efficiency at different stages. This was done by exposing apricot trees in 2 locations, during 2 periods from January to July, to the overlapping presence in the orchards of the re-immigrants and the new generation of C. pruni. The results obtained demonstrated that ‘Bergeron’ seems to be highly susceptible to ESFY: typical bud-break was rarely observed, but up to 20-30% of the plants showed premature leaf-roll, fruit deformation and dieback. C. pruni was caught only once on Picea abies during winter; “Ca. P. prunorum” was found in 4 egg samples from 2 locations and the preliminary results on the exposed trees confirmed that the re-immigrants could be the most efficient vectors at least on apricot.Keywords: Prunus armeniaca, cultivar ‘Bergeron’, Real time-PCR, “Candidatus Phytoplasma prunorum”,epidemiolog

Nonlinear Control for Reconfiguration of Unmanned-Aerial-Vehicle Formation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76757/1/AIAA-8760-121.pd

Size-resolved aerosol composition at an urban and a rural site in the Po Valley in summertime: implications for secondary aerosol formation

The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography (major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 %) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42–1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42–1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but mostly affected the small accumulation mode of particles (0.14–0.42 µm) in Bologna, while a shift to larger accumulation mode was observed at the rural site. A significant increment in carbonaceous aerosol concentration (for both WSOC and water-insoluble carbon) at the urban site was recorded mainly in the quasi-ultrafine fraction (size range 0.05–0.14 µm), indicating a direct influence of traffic emissions on the mass concentrations of this range of particles

In Vitro Synergism of Colistin and N-acetylcysteine against Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an emerging global opportunistic pathogen, responsible for a wide range of human infections, including respiratory tract infections. Intrinsic multidrug resistance and propensity to form biofilms make S. maltophilia infections recalcitrant to treatment. Colistin is among the second-line options in case of difficult-to-treat S. maltophilia infections, with the advantage of being also administrable by nebulization. We investigated the potential synergism of colistin in combination with N-acetylcysteine (NAC) (a mucolytic agent with antioxidant and anti-inflammatory properties) against S. maltophilia grown in planktonic phase and biofilm. Eighteen S. maltophilia clinical isolates (comprising three isolates from cystic fibrosis (CF) and two trimethoprim-sulfamethoxazole (SXT)-resistant strains) were included. Checkerboard assays showed a synergism of colistin/NAC combinations against the strains with colistin Minimum Inhibitory Concentration (MIC) >2 \ub5g/mL (n = 13), suggesting that NAC could antagonize the mechanisms involved in colistin resistance. Nonetheless, time-kill assays revealed that NAC might potentiate colistin activity also in case of lower colistin MICs. A dose-dependent potentiation of colistin activity by NAC was also clearly observed against S. maltophilia biofilms, also at sub-MIC concentrations. Colistin/NAC combinations, at concentrations likely achievable by topical administration, might represent a valid option for the treatment of S. maltophilia respiratory infections and should be examined further

Aging and memory phenomena in magnetic and transport properties of vortex matter: a brief review

There is mounting experimental evidence that strong off-equilibrium phenomena, such as ``memory'' or ``aging'' effects, play a crucial role in the physics of vortices in type II superconductors. We give a short review, based on a recently introduced schematic vortex model, of current progresses in understanding out of equilibrium vortex behaviours. We develop a unified description of ``memory'' phenomena in magnetic and transport properties, such as magnetisation loops and their ``anomalous'' 2nd peak, logarithmic creep, ``anomalous'' finite creep rate in the limit of vanishing temperature, ``memory'' and ``irreversibility'' in I-V characteristics, time dependent critical currents, ``rejuvenation'' and ``aging'' of the system response.Comment: updated versio