System Performance Requirements Research Articles

Research on the design of analytical communication and information model for teaching resources with cloud‐sharing platform

AbstractThe recent growth in the adoption by several organizations of cloud computing services has created the challenge to determine their performance of information model. The ability of cloud computing systems to provide the required services in line with the quality of service and service level agreement constraints is a major problem for cloud service providers and consumers. To that end, it is possible to develop the means of ensuring that the desired levels of success are achieved in simulated environments. In the eventual stage of commissioning and running cloud computing, this will reduce the disrupted service and performance degradation problems using analytical communication and information model of cloud technology. However, several modelers and simulators for simulating cloud computing systems are available in conventional research. This paper, therefore, provides a critical assessment with state of the art cloud computing modeling and simulation frameworks. It compares the prominent frameworks of simulation regarding application programming interface features, programming flexibility, operating system requirements, services supported, and licensing needs with 95% reliability. It offers recommendations to the researchers, administrators, and managers of cloud computing systems regarding the choice of the most appropriate framework.

Multi-Objective Sizing Optimization of Hybrid Renewable Energy Microgrid in a Stand-Alone Marine Context

Islands are the main platforms for exploration and utilization of marine resources. In this paper, an island hybrid renewable energy microgrid devoted to a stand-alone marine application is established. The specific microgrid is composed of wind turbines, tidal current turbines, and battery storage systems considering the climate resources and precious land resources. A multi-objective sizing optimization method is proposed comprehensively considering the economy, reliability and energy utilization indexes. Three optimization objectives are presented: minimizing the Loss of Power Supply Probability, the Cost of Energy and the Dump Energy Probability. An improved multi-objective grey wolf optimizer based on Halton sequence and social motivation strategy (HSMGWO) is proposed to solve the proposed sizing optimization problem. MATLAB software is utilized to program and simulate the optimization problem of the hybrid energy system. Optimization results confirm that the proposed method and improved algorithm are feasible to optimally size the system, and the energy management strategy effectively matches the requirements of system operation. The proposed HSMGWO shows better convergence and coverage than standard multi-objective grey wolf optimizer (MOGWO) and multi-objective particle swarm optimization (MOPSO) in solving multi-objective sizing problems. Furthermore, the annual operation of the system is simulated, the power generation and economic benefits of each component are analyzed, as well as the sensitivity.

Design and implementation of efficient Learning platform based on SpringBoot Framework

With the development of Internet technology, the demand for people's information exchange is getting higher and higher, and the traditional way of communication can no longer meet the needs of students. In order to improve the efficiency of information exchange, this paper uses a progressive framework, such as SpringBoot and Vue framework, these frameworks are easy to develop and maintain. According to these technologies, this paper designs a learning exchange community system for college students to learn and communicate. First of all, we analyze the research background and research status of learning community. Then, we analyzed the requirements of the system, including system function, performance and security requirements, and carried out the overall design of the system. The whole system is divided into several modules for development, and the specific module content is designed in detail, and the corresponding system functions are realized by using development tools. Finally, we use the black box to test the function, performance and security of the system.

Formula omitted] filtering for switched systems subject to stochastic cyber attacks: A double adaptive storage event-triggering communication

This paper concentrates on event-triggered filtering for networked switched linear systems subject to stochastic cyber attacks.A double adaptive storage event-triggering strategy (DAS-ETS) is developed. On the one hand, it can automatically adjust the amount of stored data to obtain a weighting error that more dependents on performance changes. On the other hand, its threshold is also adaptively changeable depending on system performance. Both make the strategy more accurately reflect changes in system performance requirements to trigger ‘more necessary’ events. Moreover, actual factors that stochastic cyber attacks and transmission delays are taken into account in the modeling of time-delay filtering error system. Based on Lyapunov functions and average dwell time approach, a set of criteria is provided to guarantee the realization of H∞ performance of filtering error system. Furthermore, the sub-filter gains and DAS-ETS parameters can be calculated by solving a set of linear matrix inequalities (LMIs). At last, a numerical simulation is given to confirm the advantages of the proposed solution.

To Zoom or not to Zoom? Choosing a videoconferencing platform

To Zoom or not to Zoom? Choosing a videoconferencing platform

Radio-frequency chain selection for energy and spectral efficiency maximization in hybrid beamforming under hardware imperfections

The next-generation wireless communications require reduced energy consumption, increased data rates and better signal coverage. The millimetre-wave frequency spectrum above 30 GHz can help fulfil the performance requirements of the next-generation mobile broadband systems. Multiple-input multiple-output technology can provide performance gains to help mitigate the increased path loss experienced at millimetre-wave frequencies compared with microwave bands. Emerging hybrid beamforming architectures can reduce the energy consumption and hardware complexity with the use of fewer radio-frequency (RF) chains. Energy efficiency is identified as a key fifth-generation metric and will have a major impact on the hybrid beamforming system design. In terms of transceiver power consumption, deactivating parts of the beamformer structure to reduce power typically leads to significant loss of spectral efficiency. Our aim is to achieve the highest energy efficiency for the millimetre-wave communications system while mitigating the resulting loss in spectral efficiency. To achieve this, we propose an optimal selection framework which activates specific RF chains that amplify the digitally beamformed signals with the analogue beamforming network. Practical precoding is considered by including the effects of user interference, noise and hardware impairments in the system modelling.

Blind to Chemistry: Molecular Contaminant Films We Could Be Missing During Visual Inspections and the Potential Impact to System Performance

Abstract Throughout the assembly, integration, and test process, molecular contamination levels of space mission hardware are monitored to meet system performance requirements. Qualitatively, reflective surfaces and witness mirrors are continuously inspected for the visible presence of molecular contaminant films. Quantitatively, periodic reflectance measurements of witness mirrors indicate changes of mirror reflectivity over time due to the accumulation of molecular contaminant films. However, both methods only consider the presence of a contaminant film and not the molecular composition. Additionally, there is a risk that hardware may appear to be “visibly clean” even with a molecular contaminant film present on critical surfaces. To address these issues, experiments were performed to quantify the maximum molecular contaminant film that could be missed in visual inspections on witness mirrors with five different contaminants present. The corresponding changes in mirror reflectivity were modeled using the program STACK to determine the impact to space mission hardware performance. The results of this study not only show the criticality in considering the chemical make-up of molecular contaminant films on system performance, but also the need to recognize and understand the limitations of traditional visual inspection techniques on detecting molecular contaminant films.

Optimal Sizing of an Island Hybrid Microgrid Based on Improved Multi-Objective Grey Wolf Optimizer

The hybrid renewable energy system is a promising and significant technology for clean and sustainable island power supply. Among the abundant ocean energy sources, tidal current energy appears to be very valuable due to its excellent predictability and stability, particularly compared with the intermittent wind and solar energy. In this paper, an island hybrid energy microgrid composed of photovoltaic, wind, tidal current, battery and diesel is constructed according to the actual energy sources. A sizing optimization method based on improved multi-objective grey wolf optimizer (IMOGWO) is presented to optimize the hybrid energy system. The proposed method is applied to determine the optimal system size, which is a multi-objective problem including the minimization of annualized cost of system (CACS) and deficiency of power supply probability (DPSP). MATLAB software is utilized to program and simulate the hybrid energy system. Optimization results confirm that IMOGWO is feasible to optimally size the system, and the energy management strategy effectively matches the requirements of system operation. Furthermore, comparison of hybrid systems with and without tidal current turbines is undertaken to confirm that the utilization of tidal current turbines can contribute to enhancing system reliability and reducing system investment, especially in areas with abundant tidal energy sources.

Substation Related Forecasts of Electrical Energy Storage Systems: Transmission System Operator Requirements

The growth in volatile renewable energy (RE) generation is accompanied by an increasing network load and an increasing demand for storage units. Household storage systems and micro power plants, in particular, represent an uncertainty factor for distribution networks, as well as transmission networks. Due to missing data exchanges, transmission system operators cannot take into account the impact of household storage systems in their network load and generation forecasts. Thus, neglecting the increasing number of household storage systems leads to increasing forecast inaccuracies. To consider the impact of the storage systems on forecasting, this paper presents a new approach to calculate a substation-specific storage forecast, which includes both substation-specific RE generation and load forecasts. For the storage forecast, storage systems and micro power plants are assigned to substations. Based on their aggregated behavior, the impact on the forecasted RE generation and load is determined. The load and generation are forecasted by combining several optimization approaches to minimize the forecasting errors. The concept is validated using data from the German transmission system operator, 50 Hertz Transmission GmbH. This investigation demonstrates the significance of using a battery storage forecast with an integrated load and generation forecast.

Wind generator protection with ESSs considering grid connected and island mode operations

This paper proposes a novel scheme to protect a Wind Generator (WG) with Energy Storage Systems (ESSs). In the scheme, data are dealt with in an iterative way to obtain the relay coordination considering both generator operating modes: grid connected and island. The proposition relies on conventional protection functions adapted to the operational system requirements. A set of well-known protection functions (under-voltage, over-current, differential and unbalance) operating together in an innovative arrangement, was the main objective of this research. In order to validate the proposed scheme, a Wind Energy Conversion System (WECS) with a Vanadium Redox Flow Battery (VRFB) as an EES was implemented in a real time digital simulator (RTDS®) to perform hardware-in-the-loop simulations. The simulation system consisted of a Wind Generator with grounded stator connected to the system through a DC link in order to investigate its behavior subjected to internal and external faults. Very promising results considering the proposed scheme are presented.

Evaluation of Navigation System Performance Requirements for Safe Autonomous Navigation.

This paper describes how different motion sensors can be integrated and fused to obtain necessary navigational requirements needed for autonomous operations. Both autonomous coastal navigation and automatic docking operations are analysed with respect to trade-offs in position and velocity accuracies, integrity, availability and continuity. By using AIS measurements from typical docking operations for the Norwegian coastal express vessels it is possible to define feasible safe trajectories for the docking operations. Justified requirements can be obtained using closed-loop analysis for the specific vessel and its operation. Both vessel and passenger safety can be related to vessels horizontal velocity and the safe velocity concept has been introduced to derive requirements for integrity, availability, alarm limit and continuity in case of unreported/unhandled errors in the navigation system. The outcome of this study is a design tool, or a generic methodology for selecting the most promising combination of the integrated sensor components to obtain necessary navigation system performance for safe autonomous navigation.

Optimization of a Wood Pellet Boiler System Combined with CO2HPs in a Cold Climate Area in Japan

Hot water supply is one of the leading consumers of energy in the building sector in cold climate areas. The use of woody biomass is effective in reducing CO2 emissions in hot-water supply systems. This report deals with a system that combines a wood pellet boiler (PB) and a heat pump system with CO2 (CO2HP) that is used in a facility for disabled people. The following research was conducted. The operation of a hybrid system combining a PB and CO2HPs was investigated. While operating the system, four specific operations were developed as countermeasures to save on costs and reduce system troubles while reducing CO2 emissions. The processes and results are introduced. Numerical simulations were carried out to optimize the operation. The hot water temperature, water volume, and hot water loads were simulated. The influence of the water volume ratio on the cost and primary energy consumption under the requirements for safe system operation was studied. The regional economic ripple effects (REREs) of this system were studied. The wood pellet boiler is not only a measure for reducing primary energy consumption but can also play an important role in a regional economy for sustainable development in countries that import energy resources such as Japan.

A generalised antenna correlation model for accurate performance evaluation of 2D massive MIMO communication systems

ABSTRACT Massive multiple-input multiple-output (MIMO) is considered as a key component of the new fifth-generation (5 G) communication systems and beyond to meet the rapid explosion of global wireless data traffic. However, antenna correlation is well known to have a direct impact on the capacity of practical MIMO schemes. Therefore, research and industrial communities are still looking for novel techniques to employ a large number of antennas with minimum correlation for compact mobile devices and base stations. In this paper, a realistic and generalised correlation matrix (GCM) model is developed for the accurate performance evaluation of two-dimensional (2D) massive MIMO systems. Based on the proposed GCM model, a closed-form expression of the channel capacity is derived for spatially correlated Rayleigh-fading MIMO environment to assess the acceptable range of antenna correlation. Over different 2D antenna configurations, simulation results validate the accuracy of derived capacity expression and demonstrate that the proposed GCM model tends to provide a more realistic performance compared with the existing methods. This may help to implement a large number of antennas in a constrained-size ground plane with an efficient tradeoff between 2D array designs and required system performance.

Joint Expansion Planning Studies of EV Parking Lots Placement and Distribution Network

Long-term distribution network planning (DNP) is considered as one of the most challenging issues for distribution network operators (DNOs). By increasing EVs in cities, it has appeared some new players such as electric vehicles (EVs) owners and electric vehicle parking lots (EVPLs) owners for DNP. In this article, we conduct a new study on the coupled dynamic expansion problem of EVPLs placement and distribution networks. To reach this goal, at first, EVs driving and charging/discharging behavior as some influential factors is modeled using an efficient probabilistic algorithm. An analytical model is then introduced to estimate the number of EVs in EVPLs at different times. To find out the optimal place for installing EVPLs and distribution network reinforcement, a multiobjective (MO) optimization model is formulated considering the main requirements of EVs users, EVPLs owners, and distribution system operators. A linear model is also derived for the energy monument of EVs in EVPLs and residential charging stations to be used in the mentioned MO expansion problem. Numerical results with various cases are presented to illustrate the main advantages of the proposed coupled expansion model. The simulation results indicate increasing the percentage of participated EVs in V2G leads to reduce the DNO costs and increase the EVPLs’ revenues. Moreover, the year of feeder reinforcement will be deferred by considering V2G mode and battery degradation.

Electricity markets for DC distribution systems: Locational pricing trumps wholesale pricing

DC distribution systems are a promising alternative to existing AC distribution systems. They connect customers to local energy sources without conversion, thus reducing power losses. However, the unique features of DC impose strict requirements for system operation compared to AC. Within the context of a liberalized energy market, this article demonstrates three promising market designs—an outcome of a comprehensive engineering design framework—that meet those DC requirements. They are an integrated market design, which incorporates all system costs into energy prices; a market design that passes wholesale energy prices directly to prosumers; and a locational energy market design that relieves congestion with nodal prices. An optimization model estimates the three market designs’ performance by simulating a realistic DC distribution system, featuring a high share of electric vehicles. Results indicate that the integrated market design is optimal in theory but computationally infeasible in practice. The wholesale energy price design aiming at constraint-free energy trading requires substantial investments in flexibility. The locational energy market design yields nearly optimal operation in urban networks and is considered the best feasible market design for DC distribution systems.

WHONDRS-GUI: a web application for global survey of surface water metabolites.

BackgroundThe Worldwide Hydrobiogeochemistry Observation Network for Dynamic River Systems (WHONDRS) is a consortium that aims to understand complex hydrologic, biogeochemical, and microbial connections within river corridors experiencing perturbations such as dam operations, floods, and droughts. For one ongoing WHONDRS sampling campaign, surface water metabolite and microbiome samples are collected through a global survey to generate knowledge across diverse river corridors. Metabolomics analysis and a suite of geochemical analyses have been performed for collected samples through the Environmental Molecular Sciences Laboratory (EMSL). The obtained knowledge and data package inform mechanistic and data-driven models to enhance predictions of outcomes of hydrologic perturbations and watershed function, one of the most critical components in model-data integration. To support efforts of the multi-domain integration and make the ever-growing data package more accessible for researchers across the world, a Shiny/R Graphical User Interface (GUI) called WHONDRS-GUI was created.ResultsThe web application can be run on any modern web browser without any programming or operational system requirements, thus providing an open, well-structured, discoverable dataset for WHONDRS. Together with a context-aware dynamic user interface, the WHONDRS-GUI has functionality for searching, compiling, integrating, visualizing and exporting different data types that can easily be used by the community. The web application and data package are available at https://data.ess-dive.lbl.gov/view/doi:10.15485/1484811, which enables users to simultaneously obtain access to the data and code and to subsequently run the web app locally. The WHONDRS-GUI is also available for online use at Shiny Server (https://xmlin.shinyapps.io/whondrs/).

Quantifying flexibility of load aggregations: impact of communication constraints on reserve capacity

Due to the increased use of variable renewable energy sources, more capacity for reserves is required. Non-generating resources such as thermostatically controlled loads (TCLs) can arbitrage energy prices and provide reserves due to their thermal energy storage capacity. The quantity of reserves depends not only on the aggregate power capacity, but also on information and communication technology, exogenous parameters, and system operator requirements. Specifically, the practical limitations origin from (i) communication constraints, (ii) ambient temperature, and (iii) the dispatch time of the activation signal. This study explores the impact of these parameters on the amount of reserves that an aggregator of TCLs can provide to the system operator based on centralised control of a TCL population. A decision support tool is proposed that can be used by aggregators to decide on maximum dispatchable reserve bids. The method can accommodate the specific control algorithm and TCL population of an aggregator and is based on offline computation. It constitutes a powerful reserve bid library to be used when optimisation tools become computationally intractable due to the increased number of decentralised flexible loads.

Overshoot Elimination for Control Systems with Parametric Uncertainty via a PID Controller

One of the key performance requirements for different control systems is non-overshooting step response, so that the controllable value should not overcome the reference value within a transient process. The problem of providing a non-overshooting step response was examined in this paper. Despite much scientific research being dedicated to the overshoot elimination problem, there are little to no results regarding parametric uncertainty for the discussed problem. Consideration of parametric uncertainty, particularly in the form of interval-given parameters, is essential, since in many physical processes, electronic devices and control systems parameter values can be obtained with acceptable error, and they can vary under different conditions. The main result of our research is the development of a proportional-integral-derivative (PID)-controller tuning approach for systems with interval-given parameters that provides a non-overshooting step response for such classes of control systems. This paper investigates analytical conditions and constraints for linear time invariant (LTI) systems in order to have no overshoot, enhances them with respect to parametric uncertainty, and formulates rules for tuning choices of parameters.

Position control of ball and beam system using robust h∞ loop shaping controller

<p>Laboratory Ball and Beam prototype (B&B) is a system designed to implement the controlling of space application studies such as aircraft flight and land. In this paper, to control the position of the rolling ball on the beam, MATLAB program will be used to design and implement PID and robust H<sub>∞ </sub>Loop Shaping controllers. The open loop response of the system is unstable, because the ball continuously rolling on the beam when a constant input applied. To stabilize the system, a PID controller used first to achieve the desired position. Then, robust H<sub>∞ </sub>Loop Shaping controller was used to achieve performance requirement for system with uncertainties. Results for the step response shows that robust H<sub>∞ </sub>Loop Shaping controller response have no over shoot, faster about 80 times when compared to step response of PID controller, it's more effective and had better performance compared to other controllers in the control of B&B system.</p>

Controlling Next-Generation Software-Defined RANs

Compared to previous mobile generations, the 5G system architecture offers more flexibility to fulfill a richer set of diverse requirements. Three system aspects play a major role here: support of network slicing, a split between the user plane and the control plane, and a service oriented control architecture. Emerging techniques of network softwarization such as software-defined networking are leveraged to provide this notion of flexibility manifested in a software-defined core network. However, in addition to the 5G core (5GC), analogous concepts could be applied to the next generation radio access network to sustain the required system performance. Driven by the increased attention that is currently paid to a software-defined radio access network, in this article, we propose the radio access network control function (RANCF) as an additional 5G control function. We define the main functionalities of RANCF, and propose interfaces and protocols for the interaction with 5GC functions. Exploiting network slicing as an example, we demonstrate how RANCF facilitates the slice selection and slice management procedure.