Physics of runaway electrons with shattered pellet injection at JET

Runaway electrons created during tokamak disruptions pose a threat to a reliable operation of future larger machines. Experiments using Shattered Pellet Injection (SPI) have been carried out at the JET tokamak to investigate ways to prevent their generation or suppress them if avoidance is not sufficient. Avoidance is possible if the SPI contains a sufficiently low fraction of high-Z material, or if it is fired early in advance of a disruption prone to runaway generation. These results are consistent with previous similar findings obtained with Massive Gas Injection. Suppression of an already accelerated beam is not efficient using High-Z material, but deuterium leads to harmless terminations without heat loads. This effect is the combination of a large MHD instability scattering runaway electrons on a large area and the absence of runaway regeneration during the subsequent current collapse thanks to the flushing of high-Z impurities from the runaway companion plasma. This effect also works in situations where the runaway beam moves upwards and undergoes scraping-off on the wall.

Design and Implementation of Power Network Security Protection System Based on Internet of Things

With the progress of society, the power industry is also constantly developing. This puts forward higher requirements for the safety of our country’s power grid system. In order to ensure the stable and reliable operation of the power supply network and the economic rationality, stability and security, this article first elaborates the concept of network security and network security management, secondly, it analyzes the network security protection technology. Finally, it studies the design and implementation of a store network security protection system based on the Internet of Things.

Parameter selection in data-driven fault detection and diagnosis of the air conditioning system

Data-driven fault detection and diagnosis system (FDD) has been proven as simple yet powerful to identify soft and abrupt faults in the air conditioning system, leading to energy saving. However, the challenge is to obtain reliable operation data from the actual building. Therefore, a lab-scaled centralized chilled water air conditioning system was successfully developed in this paper. All necessary sensors were installed to generate reliable operation data for the data-driven FDD. Nevertheless, if a practical system is considered, the number of sensors required would be extensive as it depends on the number of rooms in the building. Hence, parameters impact in the dataset were also investigated to identify critical parameters for fault classifications. The analysis results had identified four critical parameters for data-driven FDD: the rooms' temperature (TTCx), supplied chilled water temperature (TCHWS), supplied chilled water flow rate (VCHWS) and supplied cooled water temperature (TCWS). Results showed that the data-driven FDD successfully diagnosed all six conditions correctly with the proposed parameters for more than 92.3% accuracy; only 0.6-3.4% differed from the original dataset's accuracy. Therefore, the proposed parameters can reduce the number of sensors used for practical buildings, thus reducing installation costs without compromising the FDD accuracy.

Specific features of the static calculation of underground pipelines of gravity wastewater disposal systems

Необходимым условием экологически безопасной и надежной эксплуатации подземных трубопроводов самотечных систем водоотведения является определение требований к прочностным характеристикам элементов строительной конструкции (труб, фасонных частей), которые формируются на основании статического расчета трубопровода. При статическом расчете определяются и анализируются прямые и косвенные нагрузки, действующие на трубопровод, и производится оценка их влияния на конструкцию. Рассматриваются существующие подходы к выполнению статического расчета. На основании результатов исследований российских и зарубежных авторов утверждается, что выбор параметров труб, используемых при строительстве подземных трубопроводов, зависит не только от свойств конструкционных материалов, но прежде всего от свойств грунта, условий укладки и монтажа, а также от действующих нагрузок и степени деформации трубопровода. An essential pre-requisite for environmentally safe and reliable operation of underground pipelines of gravity wastewater disposal systems is specifying the requirements for the structural behavior of building construction elements (pipes, fittings) that are determined on the basis of a static calculation of the pipeline. In the process of the static analysis, direct and indirect loadings acting on the pipeline are determined and analyzed, and their impact on the structure is estimated. Existing approaches to performing a static analysis are considered. Based on the results of the studies carried out by Russian and foreign authors, it has been argued that the choice of the pipe parameters used in the construction of underground pipelines depends not only on the properties of structural materials, but primarily on the soil properties, conditions of laying and installation, as well as on the existing loadings and degree of pipeline deformation.

Experimental Investigation of the Fatigue Lifespan of Anchor Bolts with Consideration of Loading History

Preloaded bolted connections are one of the most used approaches for anchoring steel structures and equipment. Preload is induced by a mechanical tightening of the nut with the required torque. In the case of anchor bolts embedded in a concrete base, the prescribed tightening procedure has to be followed for safe and reliable operation. The present paper addresses the problem of anchoring a new casting pedestal using the original anchor bolts. The aim was to verify the original anchoring system’s reliable and safe operation, taking into account the current condition of the bolts. The analysed anchoring bolts are subjected to cyclic (disappearing) stress during the rotation of the casting pedestal. If the interplays between the anchor bolt and the concrete foundation were damaged, production would shut down, resulting in high economic losses. For this reason, the authors used a modified nut with a lightened first thread when investigating the actual state of the anchoring and setting the required preload. The shape and dimensions of the nut were determined based on the results of numerical modelling. The experimental measurements consisted of two phases. In the first phase, the values of axial forces in the anchor bolts at the required preload were set using the designed dynamometers. The second phase was focused on the operational measurements. The methodology of measuring the axial forces and the interpretation of the results obtained, including a comprehensive view of the anchoring safety, provides relevant evidence of the functionality and effectiveness of the proposed solution. Based on the results of the operational measurement and the prescribed handling of the casting pedestal, the lifespan of the anchoring was determined to be 3650 days under the loading cycles to date.

The Development of an Intelligent Zinc Oxide Lighting Arrester Tester

Zinc oxide arrester is often used as lightning protection device in 10KV distribution network. In order to check the reliable operation of the zinc oxide arrester, preventive tests are often carried out. In this project, the intelligent tester adopts high-precision clamp current mutual inductance technology as the front-end acquisition mode of current signals; Magnetic isolation technology is used to ensure the accuracy of current and voltage sampling and the anti-interference ability and testing accuracy of the instrument are improved by using fast Fourier transform for data processing. The integrated application of several technologies provides a basis for judging the operating state of the 10kV zinc oxide arrester. The charged measurement of operating parameters of 10kV zinc oxide arrester is realized and the measurement efficiency is improved.

Optical Inter-Satellite Link over Low Earth Orbit: Enhanced Performance

Space communication systems are traditionally operated with microwave in satellite-to-satellite links. Now, more efficient and reliable operation is required, which lead to use optical links for Inter Satellite Links (ISLs). This paper investigates the system performance of an optical ISL proposed between satellites over Low Earth Orbit (LEO). In this study, the proposed link is simulated to obtain a maximum bit rate and minimum bit error rate (BER) over different links distances. The system performance is improved by investigating its dependency on the photo detector type, operating wavelength, transmitted optical power, RZ and NRZ schemes. Our work results that best Q- factor are approximately 40 leading to a minimum BER for the LEO orbit, at 600 km when utilizing an APD. While at our investigation of the system performance at visible light bands, it is found that Q-factor will be approximately 60 achieving minimum BER with neglecting the eye-safety precautions in addition to the ability to transmit 2 Gbps at 10−9 BER within many bands.

Aged Care Energy Use and Peak Demand Change in the COVID-19 Year: Empirical Evidence from Australia

Aged care communities have been under the spotlight since the beginning of 2020. Energy is essential to ensure reliable operation and quality care provision in residential aged care communities (RAC). The aim of this study is to determine how RAC’s yearly energy use and peak demand changed in Australia and what this might mean for RAC design, operation and energy asset investment and ultimately in the healthcare plan for elderly residents. Five years of electricity demand data from four case study RACs in the same climate zone are analyzed. Statistical tools are used to analyze the data, and a clustering algorithm is used to identify typical demand profiles. A number of energy key performance indicators (KPIs) are evaluated, highlighting their respective benefits and limitations. The results show an average 8% reduction for yearly energy use and 7% reduction for yearly peak demands in the COVID-19 year compared with the average of the previous four years. Typical demand profiles for the four communities were mostly lower in the pandemic year. Despite these results, the KPI analysis shows that, for these four communities, outdoor ambient temperature remains a very significant correlation factor for energy use.

Experimental analysis of a prototype voltage stabilizer using an optoelectronic proximity voltage relay

This article discusses the issues of experimental analysis of power quality indicators when using a voltage stabilizer using an optoelectronic proximity voltage relay. Where, the booster voltage stabilizer, the magnetizing windings of which are switched using non-contact voltage relays made on the basis of semiconductor devices, as well as the duration of the transient process when switching active and active-inductive loads connected to the output of the stabilizer. In addition, the article provides information regarding the performance of the developed prototype voltage stabilizer using an optoelectronic contactless voltage relay and verification of an experimental study of the operation of installations with their use. Also presented is material on the experimental study of a prototype voltage stabilizer using an optoelectronic contactless voltage relay in various operating modes. Summarizing the results of experimental studies of a prototype voltage stabilizer using an optoelectronic contactless voltage relay, it can be stated that it fully meets the requirements for such devices and can ensure reliable operation of the power supply network of household electrical consumers.