Automatic control of the distribution of tasks under conditions of uncertainty with the use of adaptive approach

The subject of this article is the development of an adaptive approach for the optimal distribution of problems among solvers in conditions of uncertainty. Despite the large amount of research related to the construction of solutions for automatic control of task distribution, this issue remains relevant. As an alternative approach, a multi-level adaptive algorithm is proposed, which at each level filters incoming tasks according to solution methods, thereby significantly reducing the computational load. A distinctive feature of this algorithm is taking into account the time of task preprocessing, in particular, related to the current load of solvers and the distribution of tasks by solvers, in accordance with the maximum load.

Method for assessing the current and additional load on the parallel kinematic structure mechanisms electric drive system

Introduction. The problem of the load on an electric drive system in a parallel kinematic structure is considered. The task of developing a fault-tolerant system that provides performing a given process in case of a failure of one or more drives is described. The work objective is to create a method for estimating the current and additional load on each drive of the mechanism of a parallel kinematic structure. The solution enables to correct the operating mode when performing a given process without compromising serviceable drives.Materials and Methods. Previously, a diagnostic method was developed. It is based on the calculation and analysis of the coefficients of straight lines that approximate the envelopes of the values of the wavelet transform coefficients of electric motor current signals, taking into account the characteristic scales. This makes it possible to determine the current technical condition of the electric motor and find malfunctions. The logical continuation of this approach is the proposed method for assessing the current and additional load. It provides finding the current load on the drive based on the coefficients of the lines approximating the envelopes of the wavelet coefficients of the current signal. To calculate the additional load, the number and location of faulty drives are taken into account.Results. For each scale of the wavelet coefficients, the relative coefficients and the current load on each drive are determined. The possibility of redistributing the load to two adjacent jacks was checked; the behavior of the system in this case was investigated. The load moved by the faulty jack is redistributed to two adjacent jacks in equal shares — 14.76 % each. The total load on the drives is 44.28 %, which is safe for the servo. The load on the drive of the fourth jack does not change (29.52 %). The drives have a sufficient safety margin. It is established that all three operating modes are acceptable for the studied servo drive, and they do not cause dynamic overloads and premature failure.Discussion and Conclusions. The experimental studies on the method of assessing the current and additional load have shown its adequacy and high efficiency. It was found that when the drives were disconnected from one of the racks of the mechanism, the system performed a load redistribution on the drives. Thus, it was possible to avoid their dynamic overloads and premature failure. This means that the solution is able to ensure the reliable functioning of the complex at the time of renovation work.

Modeling and Analysis of Lightning Protection in an Emergency Situation of a Lightning Strike

The grounding of the supports determines the resistive, the most significant component of the overvoltage acting on the insulation gap between the lightning rod and the equipment of the electrical substation when lightning strikes the lightning rod. (Research purpose) The research purpose is in developing recommendations for the grounding devices for lightning rod supports and means of suppressing sliding spark channels in a multi-wire system. (Materials and methods) The estimation of the share of lightning current in the grounding conductor of the lightning rod support can be calculated simplistically. This makes it possible to abandon the solution of long-line wave equations and switch to a substitution scheme with concentrated parameters, in which the active and inductive resistances of sections of an electric circuit loaded with lightning current should be considered, with mandatory consideration of inductive connections between them. (Results and discussion) The article presents the calculation for a pulse with an oblique front and a flat head, which is traditionally used to estimate the number of reverse overlaps on an overhead power transmission line when a lightning strike hit a support. It was assumed that the lightning strike occurred in the extreme thunderstorm, the current load mode of which is the least favorable. The greatest current load of the grounding conductor of the support corresponds to a direct lightning strike, when the current amplitude there differs from the current amplitude of the first component in the lightning channel by no more than 25 percent, this mode should be taken as the calculated one when estimating the maximum length of the sliding spark channel. (Conclusions) The maximum lengths of sliding spark channels in soils of different conductivity were determined using computer modeling of an emergency situation of a lightning strike, provided that the reinforced concrete foundations of the lightning rod supports connected by an underground horizontal bus are used as grounding conductors of lightning rods. The most effective means of limiting the danger of sliding spark channels is their forced orientation to the side, which is safe for the grounding circuit of an electric substation.

Power Frequency Еlectromagnetic Fields of Electrical Installations in Buildings

Introduction: All components of the power supply system are sources of electric and magnetic fields of industrial frequency of 50 Hz, both posing risks to human health. Estimation of predicted magnetic field levels from switchboards and transformers inside buildings is challenging and implies the importance of full-scale measurements of electromagnetic fields from built-in electrical equipment. Objectives: To establish the levels of 50 Hz electromagnetic fields during operation of built-in electrical installations in industrial, public, and residential premises. Materials and methods: We studied 50 Hz electromagnetic fields generated by electrical installations located in buildings. EMF levels were measured near transformers, switchboards, and switchgear. The electromagnetic situation in the rooms above the electrical equipment was investigated. The assessment of EMF levels was carried out in accordance with the current hygienic standards. Results: The intensity of electric fields near the equipment and in the surveyed premises was significantly lower than that of magnetic fields. The excess of maximum permissible levels at workplaces of operators servicing EMF sources in residential buildings was not detected. In the rooms of public buildings located above electrical installations, measured values of magnetic field induction ranged from 0.18 to 31 µT. The intensity of magnetic fields depended on the current load and the distance from EMF sources. Discussion: Electromagnetic field intensity depends on specifications of equipment, current loads, and distances from the sources of electromagnetic fields. Induction of 50 Hz magnetic fields in adjacent rooms may exceed hygienic standards set for residential and public buildings. Additional adverse factors include instability of magnetic fields caused by current load changes and significant magnetic field gradients in premises.

Load Monitoring Practice in Elite Women Association Football

The description of current load monitoring practices may serve to highlight developmental needs for both the training ground, academia and related industries. While previous studies described these practices in elite men's football, no study has provided an overview of load monitoring practices in elite women's football. Given the clear organizational differences (i.e., professionalization and infrastructure) between men's and women's clubs, making inferences based on men's data is not appropriate. Therefore, this study aims to provide a first overview of the current load monitoring practices in elite women's football. Twenty-two elite European women's football clubs participated in a closed online survey (40% response rate). The survey consisted of 33 questions using multiple choice or Likert scales. The questions covered three topics; type of data collected and collection purpose, analysis methods, and staff member involvement. All 22 clubs collected data related to different load monitoring purposes, with 18 (82%), 21 (95%), and 22 (100%) clubs collecting external load, internal load, and training outcome data, respectively. Most respondents indicated that their club use training models and take into account multiple indicators to analyse and interpret the data. While sports-science staff members were most involved in the monitoring process, coaching, and sports-medicine staff members also contributed to the discussion of the data. Overall, the results of this study show that most elite women's clubs apply load monitoring practices extensively. Despite the organizational challenges compared to men's football, these observations indicate that women's clubs have a vested interest in load monitoring. We hope these findings encourage future developments within women's football.

Dynamic Windows Scheduling with Reallocation

We consider the Windows Scheduling (WS) problem, which is a restricted version of Unit-Fractions Bin Packing, and it is also called Inventory Replenishment in the context of Supply Chain. In brief, WS problem is to schedule the use of communication channels to clients. Each client c i is characterized by an active cycle and a window w i . During the period of time that any given client c i is active, there must be at least one transmission from c i scheduled in any w i consecutive time slots, but at most one transmission can be carried out in each channel per time slot. The goal is to minimize the number of channels used. We extend previous online models, where decisions are permanent, assuming that clients may be reallocated at some cost. We assume that such cost is a constant amount paid per reallocation. That is, we aim to minimize also the number of reallocations. We present three online reallocation algorithms for Windows Scheduling. We evaluate experimentally multiple variants of these protocols showing that, in practice, all three achieve constant amortized reallocations with close to optimal channel usage. Our simulations also expose interesting tradeoffs between reallocations and channel usage. We introduce a new objective function for WS with reallocations that can be also applied to models where reallocations are not possible. We analyze this metric for one of the algorithms that, to the best of our knowledge, is the first online WS protocol with theoretical guarantees that applies to scenarios where clients may leave and the analysis is against current load rather than peak load. Using previous results, we also observe bounds on channel usage for one of the algorithms.

Pulsed Reverse Potential Electrodeposition of Carbon-Free Ni/NiO Nanocomposite Thin Film Electrode for Energy Storage Supercapacitor Electrodes

A combined cyclic voltammetry and pulse reverse potential electrodeposition technique has been used to synthesize carbon-free Ni/NiO nanocomposite thin film supercapacitor electrode. The structural and morphological analyses have revealed the presence of crystalline phases of both Ni and NiO in the form of nanospheres of size ~ 50 nm. The electrochemical analysis of the Ni/NiOna nocomposite electrode has shown a remarkable performance by delivering a high specific capacitance of 2000 Fg−1 at an applied current load of 1 Ag−1 and a capacitance retention of 98.6%, after over 800 cycles under a high current load of 20 Ag−1.

Enhancing Lithium and Sodium Storage Properties of TiO2(B) Nanobelts by Doping with Nickel and Zinc

Nickel- and zinc-doped TiO2(B) nanobelts were synthesized using a hydrothermal technique. It was found that the incorporation of 5 at.% Ni into bronze TiO2 expanded the unit cell by 4%. Furthermore, Ni dopant induced the 3d energy levels within TiO2(B) band structure and oxygen defects, narrowing the band gap from 3.28 eV (undoped) to 2.70 eV. Oppositely, Zn entered restrictedly into TiO2(B), but nonetheless, improves its electronic properties (Eg is narrowed to 3.21 eV). The conductivity of nickel- (2.24 × 10−8 S·cm−1) and zinc-containing (3.29 × 10−9 S·cm−1) TiO2(B) exceeds that of unmodified TiO2(B) (1.05 × 10−10 S·cm−1). When tested for electrochemical storage, nickel-doped mesoporous TiO2(B) nanobelts exhibited improved electrochemical performance. For lithium batteries, a reversible capacity of 173 mAh·g−1 was reached after 100 cycles at the current load of 50 mA·g−1, whereas, for unmodified and Zn-doped samples, around 140 and 151 mAh·g−1 was obtained. Moreover, Ni doping enhanced the rate capability of TiO2(B) nanobelts (104 mAh·g−1 at a current density of 1.8 A·g−1). In terms of sodium storage, nickel-doped TiO2(B) nanobelts exhibited improved cycling with a stabilized reversible capacity of 97 mAh·g−1 over 50 cycles at the current load of 35 mA·g−1.

Inspection optimization of load-sharing systems

In this thesis, periodic inspection of a load-sharing k-out-of-n system has been studied to obtain the optimal inspection interval using the analytical and simulation approaches. The components of a load-sharing system are stochastically dependent, which makes the analysis of these systems more complex than those with independent components. In order to acquire the optimal inspection interval for the system, two models have been developed to study load-sharing systems with Tampered Failure Rate (TFR) and Cumulative Exposure (CE). The former considers only the current load of the components and the later accounts for the history of load. Various load intensities are examined to study the effects of this parameter on each model. It is observed that as the load intensity increases, the system needs more frequent inspections. The results also reveal that a system with the CE model requires a shorter inspection interval in comparison to that with the TFR model.