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Daylight is an inherent attribute of a sustainable building. Artificial reproduction of natural illumination under varying needs and environmental conditions has been made possible after the appearance of the new wave of solid-state light sources. Our work is devoted to the development of white light-emitting diode (LED) clusters consisting of red, green, blue, and white (RGBW) LEDs for implementation in a smart lighting system that is able to reproduce light with correlated color temperature (CCT) similar to daylight, high values of color rendering index, and luminous efficacy. A method for determination of the optimal contribution of each of the four LEDs is demonstrated and discussed. We show that only three LEDs-green, blue, and white (no red) can be used in many cases for reproducing daylight. Both luminous efficacy of radiation and actual luminous efficacy of the considered RGBW clusters as functions of the CCT are analyzed.

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Abstract-The article deals with the issues of the security of distributed and scalable computer systems based on the risk-based approach. The main existing methods for predicting the consequences of the dangerous actions of the intrusion agents are described. There is shown a generalized structural scheme of job manager in the context of a risk-based approach. Suggested analytical assessments for the security risk level in the distributed computer systems allow performing the critical t ime values forecast for the situation analysis and decisionmaking for the current configuration o f a distributed computer system. These assessments are based on the number of used nodes and data links channels, the number of act ive security and monitoring mechanisms at the current period, as well as on the intensity of the security threats realization and on the activation intensity of the intrusion prevention mechanis ms. The proposed comprehensive analytical risks assessments allow analyzing the dynamics of intrusions processes, the dynamics of the security level recovery and the corresponding dynamics of the risks level in the distributed computer system. Index Terms-Distributed computer systems, Security analysis, Risk-based approach. NOMENCLATURE α -the average intensity of the security threats for the distributed computer systems resources x1 and x2; β -the average intensity of the security mechanis ms from the group x3 and x4 activation; R 0 -the initial security risk; R(t) -security risks in the distributed computer systems, changing at time t;x 1 -the number of nodes in the distributed computer system;x 2 -the number of data link channels;x 3 -the number of the active security mechanisms; x 4 -the number of the security monitoring tools in the distributed computer systems;x 1max -the maximu m nodes number in a distributed computer system; x 2max -the maximu m number of data link channels; x 3max -the maximu m nu mber of the active security mechanisms;x 4max -the maximu m nu mber o f the security monitoring tools in the distributed computer systems.

This work is about the definition of cyber threats in the information system. The cyber threats lead to significant loss of network resources and cause the system disability as a whole. Detecting countermeasures in certain threats can reduce the impact on the system by changing the topology of the network in advance. Consequently, the interruption of a cyberattack forces the intruders to seek for alternative ways to damage the system. The most important task in the information system work is the state of network equipment monitoring. Also it's the support of the network infrastructure in working order.The purpose of the work is to develop a method for detecting cyber threats for the information system. The system can independently detect cyber threats and develop countermeasures against them. The main feature of the counteractions is to protect network nodes from compromising.To ensure the functional stability, the most important issues are providing safety metrics. This technique allows to increase the functional stability of the system, which works in real time.