Substantiation of methodical approaches to the control of indoor radon concentration in existing public buildings with non-round-the-clock stay of people

According to the analysis of requests for methodological assistance to the Saint-Petersburg Research In ­stitute of Radiation Hygiene after Professor P. V. Ramzaev, measurements of radon concentration (or radon EEC) in existing operated public buildings (primarily children institutions) in the framework of surveillance actions in the regions of the Russian Federation, as a rule, are taken according to Guidelines MU 2.6.1.2838-11, intended for radiation control of public buildings only when they are put into operation after construction, major repairs or reconstruction, due to the absence of special guidelines. Compliance with the requirements of paragraph 6.5 of MU 2.6.1.2838-11 means that the building and premises are in a state that is not equal to their normal operation mode. Registration of high values of indoor radon concentration in this case leads to management decisions, including administrative suspension o f activities for up to ninety days, i.e. the closure of individual premises or even the entire building of a children institution. The consequences of making such decisions may include an increase in social tension in society and provoking radiophobia among the population. The paper presents specific recommendations for the radon survey for existing operated public buildings with non-round-the-clock stay of people, which are based on the results of the analysis of the experience of practical application of various methods of measuring indoor radon concentrations in such buildings in order to assess average radon concentration during working hours in the normal operation mode. The proposed approach can be further used as the basis for developing special guidelines for radiation control of existing operated public buildings with non-round-the-clock stay of people.

Dynamic frequency scheduling for CubeSat's on-board and data handling subsystem

<p>CubeSat is a small-sized satellite that provides a cheaper option for the manufacturer to have a fully operational satellite. Due to its size, CubeSat can only generate limited power, and this will restrict its functionality. This research aims to improve CubeSat’s power consumption by implementing the dynamic voltage and frequency scaling (DVFS) technique to on-board and data handling subsystem (OBDH). DVFS will find the best operating frequency to execute all of OBDH’s task. This paper explains how we determined the task set, representing all routine tasks performed by OBDH during normal operation mode. We have simulated the task set using two DVFS algorithms, static earliest deadline first (EDF) and cycle conserving edf (CC EDF). The result shows that both scheduling algorithms give a similar result to our task set. However, when the scheduler is configured as non-preemptive, the simulator failed to schedule the critical task. It means that the system fails to work as intended. Therefore, we conclude that we need to implement mixed-criticality scheduling to prevent critical tasks from being aborted by the system.</p>

Impact of asymmetrical phenomena on asynchronous three-phase motors in operation mode

The general theory of three-phase motors is often built based on the assumption that the three phases voltage is symmetrical. However, in practice, this operation mode of the motor cannot be achieved due to a number of reasons such as the structure of the motor is not symmetrical, the load in the electrical system is not balanced. The asymmetry of threephase voltage greatly affects the operation mode of a three-phase asynchronous motor. The most serious affections are: decrease the starting torque, increase stator current and rotor current, vibration inside the motor. This affection will reduce the effective operation of the motor. The paper investigates the effect of asymmetry voltage on the normal operation mode of a three-phase asynchronous motor based on the electromagnetic transforming method of electric machines and simulating on Matlab-Simulink.

Enhancing Integrated Energy Distribution System Resilience through a Hierarchical Management Strategy in District Multi-Energy Systems

The requirement for energy sustainability drives the development of integrated energy distribution systems (IEDSs). In this paper, considering the coordination of district multi-energy systems (DMESs), a hierarchical management strategy is proposed to enhance IEDS resilience. The proposed strategy is divided into three modes: the normal operation mode, the preventive operation mode and the resilient operation mode. In the normal operation mode, the objective of DEMSs is to minimize the operation costs. In the preventive operation mode, the objective of DEMSs is to maximize the stored energy for mitigating outage. The resilient operation mode consists of two stages. DMESs schedule their available resources and broadcast excess generation capacities or unserved loads to neighboring DMESs through the cyber communication network in the first stage. In the second stage, DMESs interchange electricity and natural gas with each other through the physical common bus for global optimization. A consensus algorithm was applied to determine the allocated proportions of exported or imported electricity and natural gas for each DMES in a distributed way. An IEDS including five DMESs was used as a test system. The results of the case studies demonstrate the effectiveness of the proposed hierarchical management strategy and algorithm.

Modelling of magnetostriction of transformer magnetic core for vibration analysis

Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.

Low Power Test Pattern Design for VLSI Circuits Using Incorporate Pseudorandom and Deterministic Approach

The circuits should be tested extensively during the production process, the power consumption in a circuit during test mode can be higher than that the consumption during normal operation mode. The circuits are usually designed for normal operation mode, which makes it important to consider power consumption during test mode, otherwise the higher power consumption during test mode may cause the circuits being damaged. In this paper, a new approach for the test pattern design of VLSI circuits is presented, the approach defines the weight values of primary inputs of circuits, makes use of both circuit structure information and pseudorandom test generation to produce the test patterns, such that the circuit has lower power consumption when the test patterns are applied to the circuit primary inputs. The experimental results show the approach in this paper can get significant power consumption reduction compared with conventional random test algorithm.

A Microturbine Operating With Variable Heat Output

The concept of variable heat output using a recuperator bypass has been studied on a microturbine. The target of this research is to quantify to which extent variable heat output is possible using an existing microturbine design. In the paper we compare the predicted and measured performance of the system as well as present and discuss the change of NOx emissions resulting from overfiring the microturbine combustor when reducing the air preheating temperature in bypass mode. We clarify which choice of bypass is suitable considering in particular the recuperator thermo-mechanical loading. We show that the performance of the system in variable heat output can be well extrapolated with a thermodynamic model calibrated with the normal operation mode data and how experimental or theoretical data can be used to predict the change of NOx emission. It is shown that the full benefit of variable heat output can only be gained with a modified combustor design. As an example for this a lean-lean staged combutor concept is proposed.