Pre-emptive versus non-pre-emptive real time scheduling in intelligent mobile robotics

Autonomous and semi-autonomous mobile robots have to perform a multiplicity of concurrent activities in order to carry out useful tasks in unstructured human-populated environments. Even if it is commonly accepted that a successful accomplishment of assigned tasks requires some sort of real time capability to quickly react and adapt to environmental changes, it is not clear which operating system support is best suited for the scheduling and synchronizing of concurrent activities with different timing requirements. This paper discusses this problem, comparing two different real time scheduling policies for autonomous robot applications: pre-emptive rate monotonic and non pre-emptive Earliest Deadline First (EDF). Experimental results are presented and evaluated.     

Numerical analysis of a synchronization phenomenon: Pedestrian–structure interaction

The pedestrian–structure interaction is considered by developing a non-linear double pendulum model, representing the lateral walking of the pedestrian and the horizontal vibration mode of the structure. To understand the synchronization phenomenon, the two oscillators were considered in their phase spaces, and a ring-dynamics approach was applied. As synchronization occurs, pedestrian motion becomes in phase quadrature with a quarter-of-period in advance of the bridge motion: this ensures stability of walking conditions on a moving deck, but causes random cancellation of forces typical of an incoherent crowd. Correspondingly, the lateral force transmitted to the structure increases its value, approaching resonance conditions.     

A non-linear and distributed modelling procedure of fets

This paper describes a rigorous and systematic procedure to derive a non-linear distributed FET model that an easily be implemented in CAD routines of simulators based on harmonic balance techniques. The new model is derived from a knowldge of the conventional linear lumped equivalent circuit, from non-linear current sources extracted with pulsed measurements, and from the physical dimensions of the FET. For fundamental and haromonic requencies, the FET is modelled by N identical cells. Each cell is made up of a non-linear two-port section inserted between two linear four-port sections that simulate the coupling and the distributed effects along the electrodes of the FET in the width direction only. This non-linear distributed scaling approach to FET modelling has been applied to the analysis of a submicrometre-gate GaAs FET at Millimetre-wave frequencies, and the results were compared to the non-linear lumped element approach. This approach can be applied to other transistors used in non-linear regions at microwave and millimetre-wave frequencies.     

Capture of UAVs Through GPS Spoofing Using Low-Cost SDR Platforms

Wireless Personal Communications - The increased use of unmanned aerial vehicles (UAVs), better known as drones, by civilians has grown exponentially and their autonomous flight control systems...     

Malignant Transformation of Giant Cell Tumour of Bone: A Review of Literature and the Experience of a Referral Centre

Giant cell tumour of bone (GCTB) is a benign, locally aggressive primary bone neoplasm that represents 5% of all bone tumours. The principal treatment approach is surgery. Although generally GCTB is considered only a locally aggressive disease, it can metastasise, and lung metastases occur in 1–9% of patients. To date, only the use of denosumab has been approved as medical treatment for GCTB. Even more rarely, GCTB undergoes sarcomatous transformation into a malignant tumour (4% of all GCTB), but history of this malignant transformation is unclear and unpredictable. Considering the rarity of the event, the data in the literature are few. In this review, we summarise published data of GCTB malignant transformation and we analyse three cases of malignant transformation of GCTB, evaluating histopathology, genetics, and radiological aspects. Despite the rarity of this event, we conclude that a strict follow up is recommended to detect early malignant transformation.     

Electrochemical oxidation of aliphatic hydrocarbons promoted by inorganic radicals. I. OH radicals

The OH initiated oxidation of aliphatic hydrocarbons by the simultaneous electrochemical reduction of O₂ and of Fe(III) at controlled potential was investigated in the liquid phase over a Fe(III) concentration range 0.5–5 mM. OH radicals were generated by the reaction: Fe(II)+H₂O₂Fe(III)+^.OH+OH^– The compounds studied were the linear alkane hydrocarbons from C₅ to C₁₀ and 3-methyl pentane. The results showed that the ketones are the only reaction products and that the yields decrease with increasing number of carbonium atoms of the hydrocarbon. Decreasing yields were also observed with increasing Fe(III) concentration.     

Zinc Oxide Nanoparticles: Synthesis,Antimicrobial Activity and Food Packaging Applications

Zinc oxide (ZnO) is an inorganic compound widely used in everyday applications. ZnO is currently listed as a generally recognized as safe (GRAS) material by the Food and Drug Administration and is used as food additive. The advent of nanotechnology has led the development of materials with new properties for use as antimicrobial agents. Thus, ZnO in nanoscale has shown antimicrobial properties and potential applications in food preservation. ZnO nanoparticles have been incorporated in polymeric matrices in order to provide antimicrobial activity to the packaging material and improve packaging properties. This review presents the main synthesis methods of ZnO nanoparticles, principal characteristics and mechanisms of antimicrobial action as well as the effect of their incorporation in polymeric matrices. Safety issues such as exposure routes and migration studies are also discussed.     

A note on high-Q active networks

Levi's and Zeheb's approach for approximating a high-Q second-order section by n sections with lower Q's is compared with the optimal solution of this problem proposed by Khazanov. Tables relating the maximum error in the approximation to the values of n and the achievable Q-reduction (QR) are also given. They should prove useful to the designer. Finally, some comments on sensitivities are added.     

Photosynthetic membranes, 21. Immobilization of catalase by photochemically grafted ultrafiltration membranes

Catalase has been immobilized in membranes prepared by photoinduced grafting onto microporous polymeric supports and its catalytic activity on hydrogen peroxide decomposition has been studied under ultrafiltration conditions by means of a recirculation apparatus. The membranes showed a very good catalytic performance and the enzyme reaction took place exclusively within the membrane structure. Initial reaction rates measured in the temperature range 5 – 35°C as a function of both substrate concentration and enzyme amount immobilized per unit membrane surface indicate that the mechanism of action of catalase is not altered after immobilization.