Crystallization behavior,ultrahigh power density and high actual discharge energy density of lead-free borate glass-ceramics containing TiO2

This work presents SrO-BaO-Nb₂O₅-B₂O₃-P₂O₅-K₂O-TiO₂ glass-ceramics prepared by controlled crystallization method. The uniformly dense microstructure with fine grains can be achieved by introducing TiO₂. The structural changes were confirmed by the results of SEM and TEM. The 0.5 mol% TiO₂ added glass heated at 750 °C for 2 h demonstrates excellent comprehensive properties of ε_r= 110, BDS = 1408 kV/cm, high energy storage efficiency (η) of 92% and energy storage density of 9.65 J/cm³. The as-prepared glass-ceramic exhibits ultrahigh power density (86.21 MW/cm³), actual discharge energy density (1.00 J/cm³) and excellent temperature stability. These findings qualify this environment-friendly glass-ceramics as one potential candidate for energy storage applications, especially in high power and pulsed power system field.     

Synthesis of Dual Mode Logic

In recent years, the major focus of VLSI design has shifted from high-speed to low-power consumption. While standard CMOS-based digital design provides substantial flexibility during pre-silicon design phases, the characteristics of the gates are set by fabrication variations and environmental conditions and cannot easily be changed at runtime. The recently proposed Dual Mode Logic (DML) family provides a novel approach to provide this capability by introducing two configurable operating modes, static and dynamic, that enable fine-grained control of the power-performance tradeoff of a logic path. However, the introduction of a new topology requires the development of both a design methodology and techniques for integration in a robust design automation flow. Standard synthesis tools do not support dynamic gates, and in particular, dual-characteristic gates. Therefore, until now, DML has been limited to small, custom-made blocks and components. In this paper, we present a novel approach for the integration of DML into standard electronic design automation tools, as part of the standard digital design flow. The development of this approach and the accompanying design methodology enables DML to be used in larger designs, such as state-of-the-art, high-speed and/or low-power SoCs. We demonstrate the employment of the proposed approach in order to benefit from DML properties, and reduce the power consumption, while simultaneously improving the operating frequency of a number of test designs.     

A fuel cell powered autonomous surface vehicle: The Eco-SWAMP project

Autonomous surface vehicles are becoming consolidated robotic tools for marine, coastal and inland surveys. Autonomous surface vehicles are usually equipped with electronic instruments to perform remotely controlled or autonomous geo-morphological, biological, chemical, physical analyses and data collection. Actually, well-established solutions provide battery power but the research focuses on introducing a fuel cell to decrease the environmental impact meanwhile increasing the cruising range. In this paper, the design of the Eco-SWAMP, a fuel cell powered autonomous surface vehicle, is presented starting from its battery-powered version, the SWAMP prototype. The experimental power consumption profile of the SWAMP during four missions is analysed to define the primary energy sources ratings of the Eco-SWAMP. After a commercial choice of primary sources, power management algorithms are designed and compared in MATLAB/Simulink environment by simulation results. The proposed procedure can be easily applied to any autonomous marine vehicle.     

Optimal allocation of phasor measurement unit for full observability of the connected power network

This paper presents binary particle swarm optimization (BPSO) technique for the optimal allocation of phasor measurement units (PMUs) for the entire observability of connected power network. Phasor measurement units are considered as one of the most important measuring devices in the prospect of connected power network. PMUs function may be incorporated to the wide-area connected power networks for monitoring and controlling purposes. The optimal PMU placement (OPP) problem provides reference to the assurance of the minimal number of PMUs and their analogous locations for observability of the entire connected power networks. Binary particle swarm optimization (BPSO) algorithm is developed for the solution of OPP problem. The efficacy and robustness of the proposed method has been tested on the IEEE 14-bus, IEEE 30-bus, New England 39-bus, IEEE 57-bus, IEEE 118-bus and Northern Regional Power Grid (NRPG) 246-bus test system. The results obtained by proposed approach are compared with other standard methods and it is observed that this BPSO based placement of phasor measurement units is found to be the best among all other techniques discussed.     

Optimum design of a wideband planar N-way fork power divider with arbitrary power division and input-to-output impedance matching

An effective design procedure based on method of least squares is proposed for multi-section and multi-output fork power divider/combiner with arbitrary power division ratios among its outputs in a specified frequency bandwidth together with impedance matching among its arbitrary source/load impedances. Transmission and scattering matrices are obtained for its equivalent circuit. An error function is constructed based on design specifications on its output power division ratios, isolations among output ports, return losses at its input and output ports and source/load impedances in a desired frequency bandwidth. The design procedure is fully developed, which determines the widths and lengths of microstrip line sections and resistor values. A design example is described for unequal power division ratio and unequal input/output impedances. A 3-section and 3-output fork power divider is designed for equal power division and load/source impedances for 2–12 GHz band. It is fabricated and measured. Variations of its transmission coefficients are less than 0.5 dB, isolations at its outputs are better than −15 dB and reflection coefficients at its ports are better than −10 dB. Excellent agreement is observed among the results of the proposed design procedure, full wave computer software and measurement data.     

A model of driver behaviour

The driver-vehicle-environment system is characterized by the driver's ability to receive information from the environment and to react upon it by activating the controls of the vehicle. Modelling this system one has to take into account that it is complex. After introducing the model the required operations for the driver's eye and hand movements are demonstrated by means of selected examples drawn from driving-simulator runs. First analyses indicate the principal applicabilities of the fuzzy driver model for further research.     

A novel adaptive deadbeat- based control for load frequency control of low inertia system in interconnected zones north and south of Scotland

An adaptive deadbeat (ADB) controller was developed to investigate its capability in providing a fast frequency response to an electrical power system. This controller was developed to meet the requirements of the National Grid System Operability Framework (SOF), which requires frequency to be accelerated in line with a fast rate of change of frequency (RoCoF) when a high rate of nonsynchronous machines are presented. The controller’s parameters were optimized using particle swarm optimization (PSO) to ensure a robust operation and to maintain the proper operation of the power system. The design of the ADB controller was then integrated with the multiarea model of the north and south zones of Scotland. This model was developed in order to conform to the future energy requirements scenario stated by National Grid whereby regional control can be provided in both the north and south of Scotland. In comparison with the standard PI and Fuzzy-PI controllers used in the four highlighted case studies, it was shown that the ADB controller was able to significantly reduce the RoCoF and deviation of frequency when a sudden loss of generation occurred in a low inertia zone. The ADB also showed high robustness against a wide range of operating conditions.     

Fixed points of an F-contraction on metric spaces with a graph

We introduce a new type of contraction on a metric space endowed with a graph and prove fixed point theorems that generalize some of the results related with G-contraction for a directed graph G. Examples are given to justify that our contractions are more general than many others in this area.     

Optimal lot-sizing policy for a manufacturer with defective items in a supply chain with up-stream and down-stream trade credits

In this paper, we establish an economic production quantity model for a manufacturer (or wholesaler) with defective items when its supplier offers an up-stream trade credit M while it in turn provides its buyers (or retailers) a down-stream trade credit N. The proposed model is in a general framework that includes numerous previous models as special cases. In contrast to the traditional differential calculus approach, we use a simple-to-understand and easy-to-apply arithmetic–geometric inequality method to find the optimal solution. Furthermore, we provide some theoretical results to characterize the optimal solution. Finally, several numerical examples are presented to illustrate the proposed model and the optimal solution.