In this paper, a novel Power-Frequency Droop Control (PFDC) is introduced to perfectly bring back the system frequency and share the reactive power in isolated microgrid with virtual power plant (VPP). The frequency-based power delivery must be essentially implemented in VPP which can operate as a conventional synchronous generator. It has been attained by enhancing the power processing unit of each VPP to operate as an active generator. The inverter coupling impedance which has been assigned by the virtual impedance technique has reduced the affected power coupling resulting from line resistance. The reference has been subsequently adjusted to compensate the frequency deviation caused by load variation and retrieve the VPP frequency to its nominal value. In addition, the line voltage drop has compensated the voltage drop and load sharing error to obliterate the reactive power sharing imprecision resulting from the voltage deviation. The voltage feedback confirms the correct voltage after compensating the voltage drop. As an illustration, conventional PFDC after a load change cannot restore the system frequency which is deviated from 50 Hz and rested in 49.9 Hz while, proposed PFDC strategy fades away the frequency deviation via compensating the variation of the frequency reference. Likewise, the frequency restoration factor ( γ) has an effective role in retrieving the system frequency, i.e., the restoration rate of the system frequency is in proportion with γ. As a whole, the simulation results have pointed to the high performance of proposed strategy in an isolated microgrid.

This paper presents material and technological studies on lab-on-chip (LOC) devices as a first step towards biocompatible and reliable research on microscopic fungi and soil organisms on a microscale. This approach is intended to respond to the growing need for environmental control and protection, by means of modern, miniaturized, portable and dependable microfluidics instrumentation. The authors have presented herein long-term, successful cultivation of different fungi representatives (with emphasis put on Cladosporium macrocarpum) in specially fabricated all-glass LOCs. Notable differences were noted in the development of these creatures on polymer, polydimethylosiloxane (PDMS) cultivation substrates, revealing the uncommon morphological character of the fungi mycelium. The utility of all-glass LOCs was verified for other fungi representatives as well –  Fusarium culmorum and Pencilium expansum, showing technical correspondence and biocompatibility of the devices. On that basis, other future applications of the solution are possible, covering, e.g. investigation of additional, environmentally relevant fungi species. Further development of the LOC instrumentation is also taken into consideration, which could be used for cultivation of other soil organisms and study of their mutual relationships within the integrated microfluidic device.

In this present study, the effect of the shot peening process on fatigue life, surface hardness and corrosion properties of a low carbon alloy steel is examined at room temperature. The research article addresses the effect of shot peening by varying the process parameters such as peening distance and pressure with amachrome as shots. The experiment is designed by means of full factorial design. The experimental result reveals that the pressure and distance are the most significant factors in the shot peening process. The results illustrate that the average pressure of 7 bar and distance of 100 mm improves fatigue life by 1.5% of unpeened material under 20 Hz frequency while corrosion resistance improves by 4% with unpeening of the low carbon alloy steel by using amachrome as a shot.

This paper discusses the configuration of a space-effective rack cell for storing a given set of heterogeneous items. Rack cells are the primary components of rack storage areas. A rack cell configuration problem (RCCP) for heterogeneous storage is formulated as a combinatorial mathematical model. An effective heuristic for solving the RCCP in practical cases is presented. The proposed heuristic consists of multistage brute force searching of defined sets of feasible solutions and solving linear integer assignment problems by the branch-and-bound method. The developed algorithm was implemented and tested, and the rack cell obtained meets the modularity requirements in the design and operation of heterogeneous storage areas.