Efficiency of rolling schedules for a class of stochastic control problems

Analytic results are derived to compare the expected cost of using a rolling schedule (sequential open-loop optimal controller) to the minimum expected cost of employing a closed-loop optimal feedback controller for LQG control problems with varying nominal state and control trajectories and nonzero-mean disturbances. Two numerical examples illustrate the results.     

A Simple CMOS-Based Membership Function Circuit

In this study, design and analysis of a voltage-input current-output simple CMOS-based Membership Function Circuit (MFC) is presented. The proposed MFC is based on simple OTA structure and current-mode maximum circuits. This MFC implements basic four membership functions (trapezoidal, triangle, Z-shape and S-shape). The characteristics (width, height, slope and position) of the implemented membership functions are easily adjustable and it is suitable for current-mode fuzzy hardware. While the circuit's membership function characteristics have been confirmed by PSPICE-DC simulations, the circuit's transient response has been analyzed applying up to 10 MHz input signals in continuous time by PSPICE Transient simulations.     

Flexural Fatigue Behavior of Reinforced Concrete Beams Strengthened with FRP Fabric and Precured Laminate Systems

Rehabilitation of existing structures with carbon fiber reinforced polymers (CFRP) has been growing in popularity because they offer resistance to corrosion and a high stiffness-to-weight ratio. This paper presents the flexural strengthening of seven reinforced concrete (RC) beams with two FRP systems. Two beams were maintained as unstrengthened control samples. Three of the RC beams were strengthened with CFRP fabrics, whereas the remaining two were strengthened using FRP precured laminates. Glass fiber anchor spikes were applied in one of the CFRP fabric strengthened beams. One of the FRP precured laminate strengthened beams was bonded with epoxy adhesive and the other one was attached by using mechanical fasteners. Five of the beams were tested under fatigue loading for two million cycles. All of the beams survived fatigue testing. The results showed that use of anchor spikes in fabric strengthening increase ultimate strength, and mechanical fasteners can be an alternative to epoxy bonded precured laminate systems.     

Numerical and experimental investigation of two-phase flow in an electrochemical cell

In this study, a two-phase mathematical model is adapted to study void fraction distribution, flow field and characteristics of electrolysis process. The model involves transport equations for both liquid and gaseous phases. An experimental set-up is established to collect data to validate and improve the mathematical model. The void fraction is determined from measurement of resistivity changes in the system due to the presence of bubbles. It is observed that there is a good agreement between the numerical results and the experimental data.     

Memory Partitioning in the Limit

International Journal of Parallel Programming - The key difficulties in designing memory hierarchies for future computing systems with extreme scale parallelism include (1) overcoming the design...     

An Accurate Indoor RSSI Localization Algorithm Based on Active RFID System with Reference Tags

Radio frequency identification technologies are popular since their cost is very low and its data transmission based upon radio-wave communications. Where, the objects that are attached to tags are located using the reference tags. However, RSSI information suffers from the multipath propagation and anisotropic interference. So, the localization accuracy will be affected severely. Also, the multipath-propagation increases whenever the reference-tags increase, and so does for the cost, and signal interference. This paper presents a boundary virtual reference label algorithm for improving the indoor-efficiency by inserting some virtual reference tags on the boundary with establishing a linear regression model that eliminates unwanted tag information from the estimation procedure. The Results show that the localisation precision of the proposed approach has significantly increased, at least 78% without adding extra reference tags or radio frequency interference which represents a significant improvement over other algorithms .

     

Optimal parameter estimation of polymer electrolyte membrane fuel cells model with chaos embedded particle swarm optimization

Polymer electrolyte membrane fuel cells (PEMFC) are generally preferred in engineering applications due to their energy conversion efficiency, high power density, and low operating temperatures. In recent years, it has come to the fore in electric vehicles and unmanned aerial vehicle applications, which have critical and strategic importance. However, researchers use fuel cells in many different applied-theoretical studies. The models they use to increase the accuracy of these studies should be very similar to the real PEMFC. Therefore, in this paper, chaos embedded particle swarm optimization algorithm (CEPSO) and a new objective function are proposed for the first time in the literature to find the unknown parameters of PEMFC heaps more realistically. Three commercial types of PEMFCs stack namely 250 W Stack, BCS-500 W, and Nedstack PS6, which are commonly investigated in the literature, were numerically simulated to show the effectiveness of the proposes for parameter determining. The success of the suggestions is shown by the results obtained.     

Enhancement of pacemaker induced stochastic resonance by an autapse in a scale-free neuronal network

An autapse is an unusual synapse that occurs between the axon and the soma of the same neuron. Mathematically, it can be described as a self-delayed feedback loop that is defined by a specific time-delay and the so-called autaptic coupling strength. Recently, the role and function of autapses within the nervous system has been studied extensively. Here, we extend the scope of theoretical research by investigating the effects of an autapse on the transmission of a weak localized pacemaker activity in a scale-free neuronal network. Our results reveal that by mediating the spiking activity of the pacemaker neuron, an autapse increases the propagation of its rhythm across the whole network, if only the autaptic time delay and the autaptic coupling strength are properly adjusted. We show that the autapse-induced enhancement of the transmission of pacemaker activity occurs only when the autaptic time delay is close to an integer multiple of the intrinsic oscillation time of the neurons that form the network. In particular, we demonstrate the emergence of multiple resonances involving the weak signal, the intrinsic oscillations, and the time scale that is dictated by the autapse. Interestingly, we also show that the enhancement of the pacemaker rhythm across the network is the strongest if the degree of the pacemaker neuron is lowest. This is because the dissipation of the localized rhythm is contained to the few directly linked neurons, and only afterwards, through the secondary neurons, it propagates further. If the pacemaker neuron has a high degree, then its rhythm is simply too weak to excite all the neighboring neurons, and propagation therefore fails.