Superscattering and Directive Antennas via Mode Superposition in Subwavelength Core-Shell Meta-Atoms

Designing a subwavelength structure with multiple degenerate resonances at the same frequency can vastly enhance its interaction with electromagnetic radiation, as well as define its directivity. In this work we demonstrate that such mode superposition or ‘stacking’ can be readily achieved through the careful structuring of a high-permittivity spherical shell, with either a metallic or a low permittivity dielectric (air) core. We examine the behaviour of these structures both as scatterers of plane wave radiation and as directive antennas. In the case where the core is metallic this leads to a superposition of the magnetic and electric modes of the same order, causing suppression of backscattering and unidirectional antenna emission. For an air core, an electric mode can superimpose with the next-highest order magnetic mode, the backscattered power is maximized and antenna emission is bidirectional. This is shown experimentally at microwave frequencies by observing the backscattering of core-shell spheres and we propose two antenna designs demonstrating different emission patterns defined by the superposition of multiple modes.

Mathematical Modeling of the Phenomenon of Space-Charge Breakdown in the Galvanostatic Mode in the Section of the Electromembrane Desalination Channel

One of the ways to increase the efficiency of the desalination process in membrane systems is to use intensive current modes. Recently, the phenomenon of space-charge breakdown was theoretically described for desalination under intensive current modes. The space-charge breakdown is a decrease in the magnitude and size of the extended space charge regions (SCRs) of opposite signs, formed at the cation- and anion-exchange membranes in the desalination channel, when they approach each other. Therefore, this phenomenon negatively affects the intensity of electroconvection and the efficiency of mass transfer in membrane systems. We report the results of the first theoretical analysis of the space-charge breakdown in the galvanostatic electric mode, which is generally used in the research and operation of membrane systems. For this purpose, a one-dimensional model of the ion transfer of the electrolyte solution in the section of the desalination channel at the direct current is developed. The regularities of changes in the extended SCRs in the galvanostatic mode are determined. A relation is obtained for the onset time of the space-charge breakdown, which makes it possible to determine the parameters of the effective operation of the membrane system.

Vector optomechanical entanglement

The polarizations of optical fields, besides field intensities, provide more degrees of freedom to manipulate coherent light–matter interactions. Here, we propose how to achieve a coherent switch of optomechanical entanglement in a polarized-light-driven cavity system. We show that by tuning the polarizations of the driving field, the effective optomechanical coupling can be well controlled and, as a result, quantum entanglement between the mechanical oscillator and the optical transverse electric mode can be coherently and reversibly switched to that between the same phonon mode and the optical transverse magnetic mode. This ability to switch optomechanical entanglement with such a vectorial device can be important for building a quantum network being capable of efficient quantum information interchanges between processing nodes and flying photons.

A Hybrid–Electric Driveline for Agricultural Tractors Based on an e-CVT Power-Split Transmission

This paper proposes a full-hybrid driveline based on an electric continuously variable transmission (e-CVT), which is inspired by the car industry’s most successful solution. The paper describes the operating principle, the system architecture, and the control scheme of the proposed driveline. An analysis of four possible operating modes shows that the e-CVT driveline leads to a performance similar to that of conventional tractors, as well as unusual features such as power boost, full-electric mode, optimized auxiliary drive and electric power delivery capability. The compact layout proposed for the e-CVT also makes it possible to simplify the overall layout of the tractor, particularly during the installation of both the thermal engine and the cooling system.

Experimental Investigation of Innovative Thermal Mechanical Refrigeration System

The current electrical refrigeration and air condition systems are considered as one of the major sources for ozone depletion and global warming problems. Furthermore, they consume a large percentage of the worldwide gross production of electricity (around 17%). Therefore, developing new refrigeration systems that might be able to work using renewable sources (solar, geothermal, etc.) and waste heat sources is necessary to address these problems. In this paper, the experimental investigation of an innovative thermal-mechanical refrigeration (TMR) system is presented. The TMR system replaces the electric compressor of the conventional refrigeration systems with an innovative expander-compressor unit (two connected double-acting cylinders). The proposed ECU can be driven by ultra-low heat temperature sources, has simple configuration, and high flexibility for the operating conditions. A hybrid electric-compressor and ECU refrigeration setup was developed to investigate the performance of the ECU and compare it to that of an electric compressor. The experiment was conducted using R134a as a working fluid at different masses. The results show that a maximum COP of 0.57 is obtained at a refrigerant mass of 30g (in electric mode) and a maximum COP of 0.41 is obtained at a refrigerant mass of 60g (in ECU mode).

SOLAR ELECTRIC WHEELCHAIR WITH A FOLDABLE PANEL

For physically challenged individuals the most basic expression of freedom would be the ability to be mobile. Modern medical science being highly advanced designed a device of help for physically challenged individuals, called the wheelchair. The market provides a vast assortment of options in a wheelchair to fulfill the desired need and requirements of the consumer. To make the system energy efficient we have designed a solar wheelchair in which solar power is used. This keen wheelchair is additionally fitted with a leg guard for the safety of the legs. In addition, we have added a mechanism that allows our solar panel to fold and settle at a safe place, or in other terms, Solar Wheelchair with a foldable panel. All our effort has been in the direction, to make this solar-induced wheelchair at an affordable cost along with having an optimal utilization in the external as well as the internal environment. KEYWORDS: Assistive device, Electric mode, Foldable solar panel, Solar Powered Wheelchair.

Feasibility study of a diesel-powered hybrid DMU

Nowadays, the interest in hybrid vehicles is constantly increasing, not only in the automotive sector, but also in other transportation systems, to reduce pollution and emissions and to improve the overall efficiency of the vehicles. Although railway vehicles are typically the most eco-friendly transportation system, since commonly their primary energy source is electricity, they can still gain benefits from hybrid technologies, as many lines worldwide are not electrified. In fact, hybrid solutions allow ICE-powered (internal combustion engine) railway vehicles, such as diesel multiple units (DMUs), to operate in full-electric mode even when the track lacks electrification. The possibility to switch to full electric mode is of paramount importance when the vehicle runs on urban or underground track sections, where low or zero emission levels are required. We conduct the feasibility study of hybridization of an existing DMU vehicle, designed by Blue Engineering S.r.l., running on the Aosta–Torino Italian railway line, which includes a non-electrified urban track section and an electrified underground section. The hybridization is obtained by replacing one of the diesel generators installed on the original vehicle with a battery pack, which ensures the vehicle to operate in full-electric mode to complete its mission profile. The hybridization is also exploited to implement a regenerative braking strategy, which allows an increase in the energetical efficiency of the vehicle up to 18%. This work shows the sizing of the battery pack based on dynamic simulations performed on the Turin underground track section, and the results demonstrate the feasibility of the hybridization process.

ELECTRIC DEPOSITION OF TIN-LEAD ALLOY BY PULSE CURRENT

The process of electrodeposition of a tin-lead alloy from hydrofluoride electrolytes by pulsating currents has been investigated. The influence of the electric mode on the alloy composition and properties of the resulting precipitates was studied: current efficiency, microhardness, specific electrolytic resistance, and internal stresses of the precipitates.