A decentralized kinematic control architecture for collaborative and cooperative multi-arm systems

In this paper a two-layer decentralized framework for kinematic control of cooperative and collaborative multi-robot systems is developed. The motion of the system is specified at the workpiece level, by adopting a task-oriented formulation for cooperative tasks. The first layer computes the motion of the single arms in the system. In detail, the control unit of each robot computes the end-effector motion references in a decentralized fashion on the basis of the knowledge of the assigned cooperative task and the motion references computed by its neighbors. Then, in the second layer, each control unit computes the reference joint motion of the corresponding manipulator from the end-effector reference motion. The approach is, then, tested in simulation on a work-cell composed by several manipulators, and experimentally on a dual-arm kinematically redundant work-cell composed by industrial manipulators.     

Smooth migration from the GSM system to UMTS for multimedia services

Third generation of mobile systems is now entering the operational phase; European Community ACTS (RACE follow-on) programme just aims at finalizing the plenty of solutions resulting from the European Community RACE programme as well as from several other studies and researches. European manufactures, also deeply involved in the ACTS programme, seem to show a preference for solutions which gradually upgrade the present pan-European GSM successful standard. The underlying concept is the one of asmooth migration from the GSM network to the third generation system, in order to reuse, at least in the first phases of the transition, most of the existing technologies and infrastructures already implemented for the GSM network. In this respect, this paper, by referring to radio interface aspects, proposes a two step evolution: in the first step, a Dynamic Channel Allocation (DCA) strategy with distributed control should be implemented for coping with the high variance of traffic entailed by the reduction of cell dimensions; in the second step, a gradual upgrading of the GSM Base Stations should allow a smooth transition towards the third generation Packet Reservation Multiple Access (PRMA) technique and the provision of broadband services. The paper is partly based upon the work performed by the author in the framework of the RACE project Satellite Integration in the Future Mobile Network (SAINT) and of the European Community ACTS Projects MEDIAN. The opinions herewith reported are not necessarily those of the European Community.     

One Dimensional Inverse Dielectric Profiling of Embedded Slabs by a Quadratic Approximation

In this paper the inverse problem of the determination of the dielectric profile of a slab embedded into a homogeneous half space starting from the knowledge of the scattered field for different illumination angles is considered. A comparison between the features of a linear and a quadratic distorted approximation of the scattering problem is carried out, in order to determine the kind of profiles that can be reconstructed. In particular, the investigation of the direct problem reveals that, under the linear approximation, only a limited number of Fourier harmonics of the profile give contribution to the scattered field. The use of the quadratic approximation allows to change the number and order of the harmonic that can be imaged. The dependence of the results on the dielectric permittivity of the host medium is also highlighted. Numerical examples support the theoretical considerations.     

Joint near-lossless compression and watermarking of still images for authentication and tamper localization

A system is presented to jointly achieve image watermarking 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-lossless compression 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.     

White Electroluminescence by Supramolecular Control of Energy Transfer in Blends of Organic‐Soluble Encapsulated Polyfluorenes

Here, it is demonstrated that energy transfer in a blend of semiconducting polymers can be strongly reduced by non‐covalent encapsulation of one constituent, ensured by threading of the conjugated strands into functionalized cyclodextrins. Such macrocycles control the minimum intermolecular distance of chromophores with similar alignment, at the nanoscale, and therefore the relevant energy transfer rates, thus enabling fabrication of white‐light‐emitting diodes (CIE coordinates: x = 0.282, y = 0.336). In particular, white electroluminescence in a binary blend of a blue‐emitting, organic‐soluble rotaxane based on a polyfluorene derivative and the green‐emitting poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole ( F8BT ) is achieved. Morphological and structural analyses by atomic force microscopy, fluorescence mapping, µ‐Raman, and fluorescence lifetime microscopy are used to complement optical and electroluminescence characterization, and to enable a deeper insight into the properties of the novel blend.     

Capacitance DNA bio-chips improved by new probe immobilization strategies

Label-free DNA detection plays a crucial role in developing point-of-care biochips. Capacitance detection is a promising technology for label-free detection. However, data published in literature often show evident time drift, large standard deviation, scattered data points, and poor reproducibility. To address these problems, mercapto-hexanol or similar alkanethiols are usually considered as blocking agents. The aim of the present paper is to investigate new blocking agents to further improve DNA probe surfaces. Data from AFM, SPR, florescence microscopy, and capacitance measurements are used to investigate new lipoate and ethylene-glycol molecules. The new surfaces offer further improvements in terms of diminished detection errors. Film structures are investigated at the nano-scale to justify the detection improvements in terms of probe surface quality. This study demonstrates the superiority of lipoate and ethylene-glycol molecules as blocking candidates when immobilizing molecular probes onto spot surfaces in label-free DNA biochip.     

Suppressed Lattice Disorder for Large Emission Enhancement and Structural Robustness in Hybrid Lead Iodide Perovskite Discovered by High-Pressure Isotope Effect

The soft nature of organic–inorganic halide perovskites renders their lattice particularly tunable to external stimuli such as pressure, undoubtedly offering an effective way to modify their structure for extraordinary optoelectronic properties. Here, using the methylammonium lead iodide as a representative exploratory platform, it is observed that the pressure-driven lattice disorder can be significantly suppressed via hydrogen isotope effect, which is crucial for better optical and mechanical properties previously unattainable. By a comprehensive in situ neutron/synchrotron-based analysis and optical characterizations, a remarkable photoluminescence (PL) enhancement by threefold is convinced in deuterated CD₃ND₃PbI₃, which also shows much greater structural robustness with retainable PL after high peak-pressure compression–decompression cycle. With the first-principles calculations, an atomic level understanding of the strong correlation among the organic sublattice and lead iodide octahedral framework and structural photonics is proposed, where the less dynamic CD₃ND₃⁺ cations are vital to maintain the long-range crystalline order through steric and Coulombic interactions. These results also show that CD₃ND₃PbI₃-based solar cell has comparable photovoltaic performance as CH₃NH₃PbI₃-based device but exhibits considerably slower degradation behavior, thus representing a paradigm by suggesting isotope-functionalized perovskite materials for better materials-by-design and more stable photovoltaic application.