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1

A new generalized basic structure for multilevel inverter with reduced power electronic components count

Alishah Srasoul Shalchi

Journal of Power Technologies

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2022

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Vol. 102, nr 3

96--107

EN

This paper presents a new multilevel inverter topology which can generate all required numbers of levels at the output stage. The proposed topology is composed of six unidirectional switches, several bidirectional switches, and DC voltage sources. To add perspective, the proposed topology is compared with other topologies. The comparison shows that the proposed topology generates more voltage levels without the need for all excess number of switches and DC voltage sources. Moreover, the smaller number of switches in the current flow leads to decreased conductive loss in the proposed topology. To assure the proposed topology operates correctly, it is simulated with the aid of PSCAD/EMTDC software and the results are discussed.

2

Leximin Multiple Objective DCOPs on Factor Graphs for Preferences of Agents

Matsui T., Silaghi M., Okimoto T., Hirayama K., Yokoo M., Matsuo H.

Fundamenta Informaticae

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2018

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Vol. 158, nr 1/3

63--91

EN

Distributed Constraint Optimization Problem (DCOP) has been studied as a fundamental component of multiagent systems. With DCOPs, various applications on multiagent systems are formalized as constraint optimization problems where variables and functions are distributed among agents. Leximin AMODCOP has been proposed as a class of Multiple Objective DCOPs, where multiple objectives for individual agents are optimized based on the leximin operator. This problem also relates to Asymmetric DCOPs based on its the criteria of fairness among agents. Previous studies explore only Leximin AMODCOPs on constraint graphs limited to functions with unary or binary scopes. We address the Leximin AMODCOPs on factor graphs that directly represent n-ary functions. A dynamic programming method on factor graphs is investigated as an exact solution method. In addition, for relatively dense problems, we also investigate several approximate/inexact algorithms.

3

Lifting strength in two-person teamwork

Lee T. H.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 2

179--185

EN

This study examined the effects of lifting range, hand-to-toe distance, and lifting direction on single-person lifting strengths and two-person teamwork lifting strengths. Six healthy males and seven healthy females participated in this study. Two-person teamwork lifting strengths were examined in both strength-matched and strength-unmatched groups. Our results showed that lifting strength significantly decreased with increasing lifting range or hand-to-toe distance. However, lifting strengths were not affected by lifting direction. Teamwork lifting strength did not conform to the law of additivity for both strength-matched and strength-unmatched groups. In general, teamwork lifting strength was dictated by the weaker of the two members, implying that weaker members might be exposed to a higher potential danger in teamwork exertions. To avoid such overexertion in teamwork, members with significantly different strength ability should not be assigned to the same team.

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Operacjonalizacja kultury w przeciwdziałaniu zagrożeniom asymetrycznym

Trochowska K.

Zeszyty Naukowe AON

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2013

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nr 3(92)

47-74

EN

The main purpose of the article is to analyze the cultural dimension of military-led endeavors of the international community aimed at countering asymmetric threats such as post-modern terrorism and insurgencies. Although the international community agreed that military activity itself is not a proper answer to the transnational terrorist threat, the use of military components will be continued in such activities. In particular that military operations have nowadays extended way beyond the traditional, Clausewitz’s hard power concept. Not only do we observe the shift of the centers of gravity in today’s operations towards the human terrain, namely the area of operation population. Contemporary military operations also characterize with rising significance of non-kinetic elements in "COIN," anti- and counterterrorism operations, such as civil-military cooperation, civil affairs, psychological and information operations, which base on profound knowledge of adversaries’ cultures. With the emergence of population-centric operations, an urgent need of considering cultural factors of the Area of Operation emerged, and the missing link between the awareness of the cultural aspects of threats, such as also terrorist activity, and operational plans that consider them, has not yet been found and fully utilized in military planning. Therefore we face a need of the skill of operationalization of culture, understood as the identification of vital for military activities features of culture of any object of the activity, and integrating such knowledge and skills into the processes of shaping military security. Hence, although the article’s main focus is on military aspects of combating terrorism, the strategic security environment changes and the paradigm shift, demand us to consider wide, sociocultural context, not only criminal and military aspect of terrorism. Although insurgency and terrorism are not the same phenomena, their culture, motivations, mechanisms and organizational structure is alike, and they both use terrorism as heir tactics. Many of the lessons learned during counterinsurgency operations in Afghanistan and Iraq can be used while combating terrorism within military and other security operations elsewhere, not only for the needs of the military, but also other armed formations - such as the police - and civilian specialists working in the field. Gathered research proves that operationalization of culture can be an effective tool of enhancing the effectiveness of employing uniformed formations to counter violent extremisms.

5

Numeryczne modelowanie procesu walcowania Al-Mg-Al zmodyfikowaną metodą ARB

Wierzba A., Mróz S., Szota P.

Rudy i Metale Nieżelazne

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2013

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R. 58, nr 11

743--747

PL

W artykule przedstawiono wyniki badań numerycznych procesu walcowania Al-Mg-Al w pierwszym przepuście za pomocą tradycyjnej i zmodyfikowanej metody ARB. Wprowadzenie asymetrii do procesu walcowania metodą ARB spowodowało wystąpienie dodatkowych naprężeń ścinających w poszczególnych warstwach oraz na ich granicy, co powinno spowodować większe rozdrobnienie struktury (szybsze uzyskanie struktury nanometrycznej), w mniejszej liczbie przepustów oraz lepszą jakość złącza pomiędzy poszczególnymi warstwami, w porównaniu do tradycyjnego procesu walcowania metodą ARB. Materiałami zastosowanymi do badań było aluminium w gatunku 1050A oraz magnez w gatunku AZ31. Symulacje procesu walcowania wykonano za pomocą programu komputerowego Forge2011, opartego na MES.

EN

In this paper the results of the numerical studies of an Al-Mg-Al rolling process in the first pass using conventional and modified ARB method was presented. The using of asymmetry to the rolling process of ARB method caused additional shear stress in the particular layer and on the their boundary, which should cause larger refinement of structure (faster obtaining the nanometric structure) in a smaller number of the passes and better quality of interface between particular layers compared to the conventional rolling process of the ARB method. The materials used for this study was aluminum grade 1050A and magnesium grade AZ31. For the simulation of the rolling process the computer program based on FEM, Forge2011 was used.

6

Asymmetric Y-branch plastic optical fiber coupler

Ehsan A. A., Shaari S.

Optica Applicata

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2011

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Vol. 41, nr 4

807--816

EN

An acrylic-based asymmetric Y-branch plastic optical fiber (POF) coupler has been developed. The optical device is based on a Y-branch coupler design with a middle high index contrast waveguide taper and open space region for output fiber displacement. The middle waveguide taper is constructed on the acrylic block itself without using any additional optical waveguiding medium injected into the engraved taper region. The waveguide taper allows light rays to propagate by total internal reflection and this is achieved by having the material surrounding the waveguide taper to be of a lower refractive index (RI) than that of acrylic (RI of acrylic is 1.49). The area surrounding the waveguide taper has been designed in such a way that it is surrounded by an open air with an RI of 1.0. The high index contrast structure enables large splitting angle and shorter device length. Input and output POFs are inserted into this device structure in such a way that they are passively aligned to the middle waveguide taper structure. A simple attenuation technique based on lateral displacement of two fibers has been proposed and presented for the non-symmetrical coupling ratios. Numerical analysis has been made on the lateral displacement of the output fibers which shows that the device is able to generate non-symmetrical coupling ratios. A simple relationship between the coupling ratios and output fiber separation has been obtained. Device modeling has been performed using non-sequential ray tracing technique on the Y-branch coupler performing as a simple 3 dB coupler with excess loss of 1.83 dB and a coupling ratio of 50:50. The non-symmetrical coupling ratios of the device have been simulated by varying the lateral displacement of one output fiber from 0.1 mm to 4.4 mm. The results for the coupling ratios against the fiber displacement have been obtained and show how the device can be operated as an asymmetric Y-branch POF coupler.