Implementation of PID Based Controller Tuned by Evolutionary Algorithm for Double Link Flexible Robotic Manipulator

© 2018 IEEE. The paper investigates the development of intelligent hybrid collocated and non-collocated PID controller for hub motion and end point vibration suppression of double-link flexible robotic manipulator. The system was modeled using multi-layer perceptron neural network structure based on Nonlinear Autoregressive Exogenous (NARX) model. The hybrid controllers are incorporated with optimization algorithm that is ABC and PSO to find out the parameters of the PID controllers. Numerical simulation was carried out in MATLAB/Simulink to evaluate the system in term of tracking capability and vibration suppression for both links. Performance of the controllers are compared with the hybrid PID-PID Ziegler Nichols (ZN) controller in term of input tracking and vibration suppression. The results show that PSO revealed the superiority over ABC in controlling the system. The system managed to reach desired angle for both hub at lower overshoot using proposed method. Meanwhile, the vibration reduction shows great improvement for both link 1 and 2. This signifies that, the PSO algorithm is very effective in optimizing the PID parameters

The impact of contact tracing in clustered populations

The tracing of potentially infectious contacts has become an important part of the control strategy for many infectious diseases, from early cases of novel infections to endemic sexually transmitted infections. Here, we make use of mathematical models to consider the case of partner notification for sexually transmitted infection, however these models are sufficiently simple to allow more general conclusions to be drawn. We show that, when contact network structure is considered in addition to contact tracing, standard “mass action” models are generally inadequate. To consider the impact of mutual contacts (specifically clustering) we develop an improvement to existing pairwise network models, which we use to demonstrate that ceteris paribus, clustering improves the efficacy of contact tracing for a large region of parameter space. This result is sometimes reversed, however, for the case of highly effective contact tracing. We also develop stochastic simulations for comparison, using simple re-wiring methods that allow the generation of appropriate comparator networks. In this way we contribute to the general theory of network-based interventions against infectious disease

Maximizing the optical performance of planar CH3NH3PbI3 hybrid perovskite heterojunction stacks

A vapour-phase reaction process has been used to deposit smooth and uniform CH3NH3PbI3 perovskite material to enable the measurement of its optical dispersion relations, n and k, by ellipsometry. Fitting was achieved with a combination of Tauc-Lorenz, critical point parabolic band (CPPB) and harmonic oscillators. We have used the dispersion relations in an all-optical model of new planar device architectures in order to establish design rules for future materials choices to maximize the short-circuit current (Jsc) performance. For 500nm of MAPI with no window layer, the maximum performance expected from the model is Jsc=21.63mAcm-2. The ability of thin layers (in the range 20-60nm) of a range of window layer materials (TiO2, WO3, ZnO, Nb2O5, CdS, and Cd0.4 Zn0.6S) to enhance the short-circuit current of the devices was investigated. The performance of the oxides showed interference behaviour, with the first maxima in their J sc curves exceeding the value achievable without a window layer. However, after the first maximum, the performance generally fell off with increasing thickness. The only material to stay greater than the no-window condition for the entire investigated range is WO3. The highest performance (J sc of 22.47mAcm-2) was obtained with 59nm of WO3, with that of TiO2, ZnO, and Nb2O5 being marginally lower. Parasitic absorption in CdS window layers caused the J sc to decrease for all non-zero thicknesses - it gives no interference enhancement and its use cannot be recommended on optical grounds. Use of the wider gap alloy Cd0.4Zn0.6S gave higher currents than did CdS but its performance was not so high as for the oxides. Observations are made on the practicalities of fabricating the target structures in the fabrication of practical PV devices

Schottky Diodes on ZnO Thin Films Grown by Plasma-Enhanced Atomic Layer Deposition

Enhancement of the properties of zinc oxide (ZnO)-based Schottky diodes has been explored using a combination of plasma-enhanced atomic layer deposition (PE-ALD) ZnO thin films and silver oxide Schottky contacts deposited by reactive radio-frequency sputtering. The electrical properties of the ZnO thin films were systematically tuned by varying the deposition temperature and oxygen plasma time during PE-ALD to optimize the performance of the diode. Low temperature (80 °C) coupled with relatively long oxygen plasma time (>30 s) PE-ALD is the key to produce ZnO films with net doping concentration lower than 10 17 cm -3 . Under the optimal deposition conditions identified, the diode shows an ideality factor of 1.33, an effective barrier height of 0.80 eV, and an ON/OFF ratio of 3.11 × 10 5

Exploring pig trade patterns to inform the design of risk-based disease surveillance and control strategies

An understanding of the patterns of animal contact networks provides essential information for the design of risk-based animal disease surveillance and control strategies. This study characterises pig movements throughout England and Wales between 2009 and 2013 with a view to characterising spatial and temporal patterns, network topology and trade communities. Data were extracted from the Animal and Plant Health Agency (APHA)’s RADAR (Rapid Analysis and Detection of Animal-related Risks) database, and analysed using descriptive and network approaches. A total of 61,937,855 pigs were moved through 872,493 movements of batches in England and Wales during the 5-year study period. Results show that the network exhibited scale-free and small-world topologies, indicating the potential for diseases to quickly spread within the pig industry. The findings also provide suggestions for how risk-based surveillance strategies could be optimised in the country by taking account of highly connected holdings, geographical regions and time periods with the greatest number of movements and pigs moved, as these are likely to be at higher risk for disease introduction. This study is also the first attempt to identify trade communities in the country, information which could be used to facilitate the pig trade and maintain disease-free status across the country in the event of an outbreak

Conformal Bulk Fields, Dark Energy and Brane Dynamics

In the Randall-Sundrum scenario we analyze the dynamics of a spherically symmetric 3-brane when the bulk is filled with matter fields. Considering a global conformal transformation whose factor is the $Z_2$ symmetric warp we find a new set of exact dynamical solutions for which gravity is bound to the brane. The set corresponds to a certain class of conformal bulk fields. We discuss the geometries which describe the dynamics on the brane of polytropic dark energy.Comment: 12 pages, latex, 2 figures. Talk given by Rui Neves at the Fourth International Conference on Physics Beyond the Standard Model, Beyond the Desert 03, Fundamental Experimental and Theoretical Developments in Particle Physics, Accelerator, Non-Accelerator and Space Approaches, Max Planck Institut f. Kernphysik/MPI Heidelberg, Castle Ringberg, Tegernsee, Germany, 9-14 June 2003. To be published in the Conference Proceedings, Springer-Verlag, Heidelberg, German

A monotonic relationship between the variability of the infectious period and final size in pairwise epidemic modelling

For a recently derived pairwise model of network epidemics with non-Markovian recovery, we prove that under some mild technical conditions on the distribution of the infectious periods, smaller variance in the recovery time leads to higher reproduction number, and consequently to a larger epidemic outbreak, when the mean infectious period is fixed. We discuss how this result is related to various stochastic orderings of the distributions of infectious periods. The results are illustrated by a number of explicit stochastic simulations, suggesting that their validity goes beyond regular networks