Trajectory Tracking Using Adaptive Fractional PID Control of Biped Robots with Time-Delay Feedback

This paper presents the application of fractional order time-delay adaptive neural networks to the trajectory tracking for chaos synchronization between Fractional Order delayed plant, reference and fractional order time-delay adaptive neural networks. For this purpose, we obtained two control laws and laws of adaptive weights online, obtained using the fractional order Lyapunov-Krasovskii stability analysis methodology. The main methodologies, on which the approach is based, are fractional order PID the fractional order Lyapunov-Krasovskii functions methodology, although the results we obtain are applied to a wide class of non-linear systems, we will apply it in this chapter to a bipedal robot. The structure of the biped robot is designed with two degrees of freedom per leg, corresponding to the knee and hip joints. Since torso and ankle are not considered, it is obtained a 4-DOF system, and each leg, we try to force this biped robot to track a reference signal given by undamped Duffing equation. To verify the analytical results, an example of dynamical network is simulated, and two theorems are proposed to ensure the tracking of the nonlinear system. The tracking error is globally asymptotically stabilized by two control laws derived based on a Lyapunov-Krasovskii functional

Slow and Fast Neocortical Oscillations in the Senescence-Accelerated Mouse Model SAMP8

The senescence-accelerated mouse prone 8 (SAMP8) model is characterized by accelerated, progressive cognitive decline as well as Alzheimer's disease (AD)-like neurodegenerative changes, and resembles the etiology of multicausal, sporadic late-onset/age-related AD in humans. Our aim was to find whether these AD-like pathological features, together with the cognitive deficits present in the SAMP8 strain, are accompanied by disturbances in cortical network activity with respect to control mice (SAM resistance 1, SAMR1) and, if so, how the alterations in cortical activity progress with age. For this purpose, we characterized the extracellular spontaneous oscillatory activity in different regions of the cerebral cortex of SAMP8 and SAMR1 mice under ketamine anesthesia at 5 and 7 months of age. Under these conditions, slow oscillations and fast rhythms generated in the cortical network were recorded and different parameters of these oscillations were quantified and compared between SAMP8 and their control, SAMR1 mice. The average frequency of slow oscillations in SAMP8 mice was decreased with respect to the control mice at both studied ages. An elongation of the silent periods or Down states was behind the decreased slow oscillatory frequency while the duration of active or Up states remained stable. SAMP8 mice also presented increased cycle variability and reduced high frequency components during Down states. During Up states, the power peak in the gamma range was displaced towards lower frequencies in all the cortical areas of SAMP8 with respect to control mice suggesting that the spectral profile of SAMP8 animals is shifted towards lower frequencies. This shift is reminiscent to one of the principal hallmarks of electroencephalography (EEG) abnormalities in patients with Alzheimer's disease, and adds evidence in support of the suitability of the SAMP8 mouse as a model of this disease. Although some of the differences between SAMP8 and control mice were emphasized with age, the evolution of the studied parameters as SAMR1 mice got older indicates that the SAMR1 phenotype tends to converge with that of SAMP8 animals. To our knowledge, this is the first systematic characterization of the cortical slow and fast rhythms in the SAMP8 strain and it provides useful insights about the cellular and synaptic mechanisms underlying the reported alterations

Pressurized multiwire proportional chamber for neutron imaging

A pressurizable neutron-sensitive multi-wire proportional chamber has been constructed to test the effect of increased gas density on image resolution. The chamber has dimensions of 25 cm x 25 cm and is pressurizable to 4 atm. With a single-plate converter the thermal-neutron detection efficiency was 6.3 percent for gadolinium and 2.3 percent for boron-10. For a four-fold increase in chamber pressure the overall resolution improved more than a factor of two for boron, but relatively little for gadolinium. The effects of cathode biasing is also discussed

Search for 1-Mev Gamma from N16 Decay

In the beta-decay of N16 to the 1- (7.1-Mev) and 3- (6.1-Mev) excited states of O16, respectively, a discrepancy exists between the branching ratio of about 1:1 determined from absorption measurements on the beta-spectrum, and the ratio of about 1:12 from measurement of the associated gamma-ray intensities. If both measurements are to be reconciled, the most likely possibility is a strong E2 gamma-ray transition from the 7.1-Mev to the 6.1-Mev level. The likelihood that this E2could give serious competition to the normal 7.1-Mev E1 ground state transition is enhanced by the isotopic spin selection rule forbidding E1 transitions with [delta]T = N - Z = 0. In order to explain the quantitative discrepancy in this way, however, this selection rule would have to be much stronger than suggested by simple estimates

3-D object reconstruction emission and transmission tomography with limited angular input

The effects of the angular range of data taking in reconstructions in planar positron cameras using the deconvolution method and the matrix method, respectively, are investigated. It is found that in the absence of any a priori information there are undetermined components in the reconstruction if the field of view of the positron camera is limited. However, most of the undetermined components are recovered in the case in which the transverse spacing of the object is discrete, and all of them are recovered if the fact that the object extent is finite is utilized. It is concluded that the two reconstruction methods are mathematically equivalent. The results obtained can be applied to other transmission and emission imaging devices

Role of Plasticizers on PHB/bio-TPE Blends Compatibilized by Reactive Extrusion

Poly(hydroxybutyrate) (PHB) is a biopolymer biologically synthesized by controlled bac- terial fermentation from a wide variety of microorganisms. PHB is proposed as a potential green alternative to commonly used plastics in packaging, due to its biodegradability and biocompatibility. However, if PHB is to replace commodities, it has some limitations regarding its thermo-mechanical performance to overcome. Among them are its critically the low toughness values at room tem- perature and poor thermoforming ability. With the aim of overcoming these weaknesses, in this work, blends of PHB with the addition of a biodegradable thermoplastic elastomer (bio-TPE) were prepared and evaluated. Films of such compounds were made by cast extrusion. In order to enhance the compatibility of both polymers during the extrusion process, three different reactive agents (poly-hexametylene diisocianate, triglycidyl isocyanurate, and Joncryl® ADR-4368) were assessed. The morphology and mechanical- and thermal properties of the films obtained were analyzed. In addition, the thermoforming ability of the produced films was evaluated. The results show that the plasticizers present in the bio-TPE interacted with the reactive agents, making them chemical competitors and altering the outcome of the blends

Inference of the stability of global states in cortical networks

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Detection of charged particles in amorphous silicon layers

The successful development of radiation detectors made from amorphous silicon could offer the possibility for relatively easy construction of large area position-sensitive detectors. We have conducted a series of measurements with prototype detectors, on signals derived from alpha particles. The measurement results are compared with simple model calculations, and projections are made of potential applications in high-energy and nuclear physics. 4 refs., 7 figs

Mechanical Biosensors in Biological and Food Area: a Review

A review of state the art about the structure, classification and operation of biosensors applied in food and biological areas is presented. This review is focused to mechanical biosensors that use mill, micro and nanocantilevers. Basic concepts of atomic force microscopy and optical systems, used as testing platform of biosensors are described. The most funcionalized strategies and geometrical configurations are also explained. Mathematical methods for evaluating the performance in static and dynamic mode of the mechanical biosensors are reviewed and examples of application in biological and food areas are provided. An overall description of the operational effect of operation conditions and design variables on the sensitivity devices is also proposed. A brief description of the design processes and manufacturing of cantilevers based silicon technology as well as information about BioMEMS and BioNEMS are provided. Finally, overall tends in research, development and commercialization of biosensors are described briefly as well as probable areas of development in food biosensors. Thereby, this review provides an overall view of biosensors, as an exploratory guide to identify the most important aspects of this technology