Stand-alone Scheme Research Articles

Gate-Controlled Anyon Generation and Detection in Kitaev Spin Liquids.

Reliable manipulation of non-Abelian Ising anyons supported by Kitaev spin liquids may enable intrinsically fault-tolerant quantum computation. Here, we introduce a standalone scheme for both generating and detecting individual Ising anyons using tunable gate voltages in a heterostructure containing a non-Abelian Kitaev spin liquid and a monolayer semiconductor. The key ingredients of our setup are a Kondo coupling to stabilize an Ising anyon in the spin liquid around each electron in the semiconductor, and a large charging energy to allow control over the electron numbers in distinct gate-defined regions of the semiconductor. In particular, a single Ising anyon can be generated at a disk-shaped region by gate tuning its electron number to one, while it can be interferometrically detected by measuring the electrical conductance of a ring-shaped region around it whose electron number is allowed to fluctuate between zero and one. We provide concrete experimental guidelines for implementing our proposal in promising candidate materials like α-RuCl_{3}.

The hybrid power generation and balancing energy supply–demand for rural village in Ethiopia

AbstractEthiopia has a wide range of environmentally‐friendly, renewable energy resources that can assist the country to overcome its rural electricity problems. The Hybrid Optimization Model for Multiple Energy Resources (HOMER) software package was used to evaluate the viability of solar, hydro and wind hybrid power generation for a remote community in Ethiopia's Geba catchment. The hydrologic, climatic and demographic data were used to analyze the community's electrical supply and demand. Using survey data from chosen residences, the community's hourly and daily electricity demands were calculated. Two or more schemes were investigated besides the standalone scheme to assess the hybrid system's capacity. Wind, micro‐hydro and solar can generate an average annual power of 96.8, 272.4 and 161.8 kW, respectively. A mix of energy sources can meet the community's electricity demand. During peak demand periods, however, the hybrid system's mean hourly variability in power production showed inadequacy, which could be remedied by power stored in the battery and generator output. The economic analysis showed that the hybrid system proposed here is less expensive, indicating that hybrid energy generation might be employed to electrify Ethiopia's remote settlements. We advise decision‐makers and power authorities to use hybrid systems for rural electrification.

A New Switching Strategy for Improving Efficiency and Thermal Distribution of a Three-Port Converter for Solar DC Stand-Alone System

This brief proposes a new switching scheme for a recently published three-port converter to make it suitable for Photo-Voltaic (PV) fed dc stand-alone system with battery backup. The resulted scheme is capable of Maximum Power Point (MPP) Tracking, charging, and discharging of the battery, and can feed power to the load while maintaining the desired load voltage. This scheme, when operated with a saw-tooth or triangle carrier, leads to improved efficiency and dynamic response as compared to existing similar schemes reported in the literature. This brief also proffers toggling between saw-tooth and triangle carriers periodically for better thermal distribution in the switching devices which is envisaged to enhance the reliability of the overall system. A suitable control strategy is also proposed for the complete stand-alone scheme to facilitate operation in various possible modes along with smooth transition between these modes. Small signal analysis is performed based on the proposed switching scheme, and the controller design during various operating modes is discussed. Validation and performance analysis of the overall system are carried out under various operating conditions utilizing a 400W experimental prototype.

The impact of the Nottingham Workplace Parking Levy on travel to work mode share

A Workplace Parking Levy (WPL) scheme raises a levy on private non-domestic off-street parking provided by employers. In April 2012 Nottingham became the first UK City to implement such a scheme with the revenue generated hypothecated for funding two additional tram lines into the city, the refurbishment of the main railway station and enhancements to a number of bus services.Evaluations of similar Parking Space Levies schemes in Australia show that their introduction, along with any transport improvements they part fund, have been followed by mode switch to non-car based modes, a pre-requisite for congestion constraint. The aim of this paper is to investigate the impact the introduction of the Nottingham Workplace Parking Levy and its associated transport improvements has had on transport mode choice for commuters. This research however, does not directly demonstrate cause and effect leaving open the possibility that the observed mode shift could be caused by exogenous factors. The paper is based on data collected from a survey of 2500 commuters in Nottingham, relating to their mode choice.The results indicate that 8.6% of commuters currently travelling by sustainable modes switched from the car between 2010 and 2016 at least in part due to the implementation of the WPL and/or the associated transport improvements. In the region of 50 per cent of those individuals gave the WPL as a stand-alone scheme as an important factor in their decision to shift away from the car via an increase in the cost of parking at work or because their employer had removed workplace parking spaces. However, this research has also revealed evidence of commuters switching to the car away from other modes demonstrating a significant suppressed demand for travel by car which in part offsets some of the beneficial impacts of the WPL package.

Improved relaxation zone method in SPH-based model for coastal engineering applications

An improved Relaxation Zone (RZ) method has been implemented in the meshless SPH-based DualSPHysics model. Final purpose of this work is to have a general wave generation scheme that allows coupling SPH-based models to other models, e.g. Eulerian based wave models, besides employing the RZ as alternative wave generation in SPH as a stand-alone scheme. Using RZ in SPH, the movement of the fluid particles is controlled by correcting their orbital velocity by means of a weighting function in a specified generation area. In the present work, the new technique is used to couple DualSPHysics to the non-hydrostatic wave-flow model SWASH. The results of RZ employed both as stand-alone wave generation technique and as coupling framework with SWASH model are validated for wave generation and wave reflection for monochromatic waves. Then, the method is tested successfully for generation and absorption of irregular waves. Finally, the coupling between DualSPHysics and SWASH using RZ is validated against experimental data concerning the wave flow impacts on vertical walls. A procedure for a proper design of the RZ (i.e. shape of the weighting function, size of the RZ) is described in the present work. Overall, the results indicate that the proposed improved RZ technique is among the most effective alternatives for wave generation in SPH-based models for coastal engineering application.

An Efficient Uplink Multi-Connectivity Scheme for 5G Millimeter-Wave Control Plane Applications

The millimeter wave (mmWave) frequencies offer the potential of orders of magnitude increases in capacity for next-generation cellular systems. However, links in mmWave networks are susceptible to blockage and may suffer from rapid variations in quality. Connectivity to multiple cells - at mmWave and/or traditional frequencies - is considered essential for robust communication. One of the challenges in supporting multi-connectivity in mmWaves is the requirement for the network to track the direction of each link in addition to its power and timing. To address this challenge, we implement a novel uplink measurement system that, with the joint help of a local coordinator operating in the legacy band, guarantees continuous monitoring of the channel propagation conditions and allows for the design of efficient control plane applications, including handover, beam tracking and initial access. We show that an uplink-based multi-connectivity approach enables less consuming, better performing, faster and more stable cell selection and scheduling decisions with respect to a traditional downlink-based standalone scheme. Moreover, we argue that the presented framework guarantees (i) efficient tracking of the user in the presence of the channel dynamics expected at mmWaves, and (ii) fast reaction to situations in which the primary propagation path is blocked or not available.

Performance Improvement of Satellite Navigation System Using Inter-satellite Distance Information

A satellite navigation system calculates the position of a user using measurement values from a satellite, receiver, and broadcast ephemeris, which provides position information about the navigation satellite. However, in scenarios where it is difficult to secure sufficient satellite visibility, such as in a downtown area, the position accuracy of a global navigation satellite system is reduced. This study proposes a navigation algorithm for improving the accuracy of navigation using a measurement value in addition to the existing pseudorange measurement. A user who cannot secure a sufficient navigation visibility uses a standalone scheme that depends exclusively on the pseudorange measurement to estimate the position. The proposed method uses a position estimation algorithm that uses the measured value of the distance between satellites and geometric relation between users to construct a measurement equation, and combines this with the existing pseudorange measurement equation. The results obtained from static and dynamic experiments verify the superior performance of the proposed navigation algorithm.

Solar photovoltaic‐based stand‐alone scheme incorporating a new boost inverter

This study considers the design of a solar photovoltaic (PV)-based stand-alone system using a battery for energy storage. Its main feature is a new boost inverter, derived by integrating a dc–dc buck–boost converter and a full bridge dc–ac inverter, which can perform simultaneous voltage boosting and dc–ac conversion. Inclusion of this inverter has led to the development of a three stage stand-alone scheme which can operate with low voltage level(s) for the PV and the battery. The logical evolution and operating principles of this inverter are presented, followed by an overview of the entire stand-alone scheme and its control structure. The complete scheme is validated both by detailed simulation studies and exhaustive experimental studies on a laboratory prototype.

Two-Stage Solar Photovoltaic-Based Stand-Alone Scheme Having Battery as Energy Storage Element for Rural Deployment

Solar photovoltaic (PV)-based stand-alone systems have evolved as a promising solution to the issue of electrification in areas where the grid is not available. The major challenges in designing such systems are as follows: 1) extraction of maximum power from the PV array; 2) protection of the battery from overcharge and overdischarge; 3) dc to ac conversion; and 4) provision for adequate voltage boosting. As multiple objectives are required to be satisfied, the existing schemes for stand-alone systems require a minimum of three converter stages, leading to considerable reduction in the reliability and efficiency of the system. In order to address this issue, a two-stage stand-alone scheme consisting of a novel transformer-coupled dual-input converter (TCDIC) followed by a conventional full-bridge inverter is proposed in this paper. The proposed TCDIC can realize maximum power point tracking and battery charge control while maintaining the proper voltage level at the load terminal. The small signal mathematical model of the TCDIC is derived. A suitable control strategy for the proposed TCDIC is devised. The operation of the scheme is verified by performing detailed simulation studies. A laboratory prototype of the scheme is developed. Detailed experimental validation of the scheme utilizing the laboratory prototype is carried out to confirm the viability of the scheme.

ROBERTSBRIDGE FLOOD ALLEVIATION SCHEME: THE CHALLENGES OF A FAST-TRACK APPROACH

Flooding occurred in many locations in the United Kingdom in the autumn/winter of 2000. One of the worst affected areas was Robertsbridge, in East Sussex, where, over that winter, some properties were flooded up to eight times. Following those events, the Environment Agency targeted defences for this high-risk township as one of Its high priority projects to 'fast-track' to implementation. Studies started in January 2001, which recommended a stand-alone scheme that would protect the township against the 1% probability flood. Project development progressed on a 'fast-track' basis to allow construction to start in September 2002 with completion planned In the summer of 2003. Project development and implementation is always an obstacle course but the 'fast-track' approach magnifies the obstacles and introduces new ones. This paper describes experience from the Robertsbridge flood alleviation scheme, with particular reference to some of the problems encountered, both technical and procedural.

Design of land-air parameterization scheme (LAPS) for modelling boundary layer surface processes

A land-air parametrization scheme (LAPS) describes mass, energy and momentum transfer between the land surface and the atmosphere. The scheme is designed as a software package which can be run as part of an atmospheric model or a stand-alone scheme. A single layer approach is chosen for the physical and biophysical scheme background. The scheme has six prognostic variables: two temperatures (one for the canopy vegetation and one for soil surface), one interception storage, and three soil moisture storage variables. The scheme's upper boundary conditions are: air temperature, water vapour pressure, wind speed, radiation and precipitation at some reference level within the atmospheric boundary layer. The sensible and latent heat are calculated using resistance representation. The evaporation from the bare soil is parametrized using the “α” scheme. The soil part is designed as a three-layer model which is used to describe the vertical transfer of water in the soil.