General Commutation Research Articles

A General Self-Adaptive DC Current Control of LCC-HVDC for Eliminating Subsequent Commutation Failure

With more renewable resources are integrated into the receiving-end AC grid through the LCC-HVDC link, a single-infeed LCC-HVDC (SIDC) system is facing a critical subsequent commutation failure (SCF), which stems from the poor dynamic reactive power support capability of the existing LCC-HVDC link's control strategies. This letter proposes a general self-adaptive DC current control (GSDC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) of LCC-HVDC to eliminate the SCF, based on the dynamic reactive power interaction mechanism. Then, multiple comparative studies with the existing control strategies are implemented to verify the validation of the proposed control strategy by PSCAD/EMTDC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sup> . A fast evaluation index, called general commutation failure immunity index (GCFII), is also defined to show the performance of the proposed control strategy in eliminating the SCF.

Probabilistically nilpotent groups of class two

For G a finite group, let d2(G)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d_2(G)$$\\end{document} denote the proportion of triples (x,y,z)∈G3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(x, y, z) \\in G^3$$\\end{document} such that [x,y,z]=1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$[x, y, z] = 1$$\\end{document}. We determine the structure of finite groups G such that d2(G)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d_2(G)$$\\end{document} is bounded away from zero: if d2(G)≥ϵ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d_2(G) \\ge \\epsilon > 0$$\\end{document}, G has a class-4 nilpotent normal subgroup H such that [G : H] and |γ4(H)|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|\\gamma _4(H)|$$\\end{document} are both bounded in terms of ϵ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon $$\\end{document}. We also show that if G is an infinite group whose commutators have boundedly many conjugates, or indeed if G satisfies a certain more general commutator covering condition, then G is finite-by-class-3-nilpotent-by-finite.

Observables physics general formalism

Observables form the most important real physics proof processes that will make normal science. Since mathematics have integral part in quantifying physical phenomena, theory involves modeling hypothetical logic borne within observations. A proper theory will need to show pulling out observables from parameters using abstractions. These processes that have gotten derived elsewhere are reviewed here in a gist manner that author has been able to configure as a fundamentally grand unifying realistic physics without assumptive inconsistencies. Review here also shows corrections of errata in earlier publications to help applications to wider areas of not only physical sciences but also mathematical computing information technology algorithms’ developments. Iyer-Markoulakis formalism to gage micro to macro by applying Coulomb-Hilbert gage from mechanics of gradient vortex fields to electromagnetic fields and then to gravitational aspects have been explained. Quantitative derivation of a general potential wave quantum density commutator matrix physics, with subsequent gauge equivalent expressions have been advanced. Mathematical modeling has been briefed on theorizing point dynamics Helmholtz decomposition fields’ quantum Hamiltonian matrix evolving with time. Partial differential equations that have gotten derived from these characteristic matrices for zero-point as well as microblackhole aspects of a point in sense-time-space dimensions have highlighted addressing real world complexity manifested by these pure logical equations. Gaging with algorithmically elaboratively extended analysis with observables provide fitting completions to the partial differential equations (P.D.E.) of energy and quantum field metrix within Iyer-Markoulakis-Hodge-O’Neill-Malaver-Zhang-Taylor formalisms that provide best hope towards grand unification of the four super forces that physics portrays to natural workings of the universe. Retrofitting Iyer Markoulakis gradient vortex gage fields eigen matrix formalism to Wenzhong Hodge scalar frictional vacuum theory of hod-Plenum, dissipative discontinuity of modeling gage physics, giving an Integral Model Astro Quantum PHYSICS has shown to be achievable. Matrix general form algorithm equation, having gage functional, signal/noise ratio, gage fields, wavefunction inner outer products, quantum density matrix as a function of gage time configured successfully. Application to observables practically for analysis has been exemplified to mesoscopic population pattern with gage fields of pressure and temperature.

Future aircraft concepts and design methods

AbstractWith an annual growth in travel demand of about 5% globally, managing the environmental impact is a challenge. In 2019, the International Civil Aviation Organisation (ICAO) issued emission reduction targets, including well-to-wake greenhouse gas (GHG) emissions reduced at least 50% from 2005 levels by 2050. This discusses several technologies from an aircraft design perspective that can contribute to achieving these targets. One thing is certain: aircraft will look different in the future. The Transonic Truss-Braced Wing and Flying V configurations are promising significant efficiency improvements over conventional configurations. Electric propulsion, in various architectures, is becoming a feasible option for general aviation and commuter aircraft. It will be a growing field of aviation with zero-emissions flight and opportunities for special missions. Lastly, this paper discusses methods and design processes that include all relevant disciplines to ensure that the aircraft is optimised as a complete system. While empirical methods are essential for initial design, Multidisciplinary Design Optimisation (MDO) incorporates models and simulations integrated in an optimisation environment to capture critical trade-offs. Concurrent design places domain experts in one site to facilitate collaboration, interaction, and joint decision-making, and to ensure all disciplines are equally considered. It is supported by a Collaborative Design Facility (CDF), an information technology facility with connected hardware and software tools for design analysis.

Do migrants and locals differ in commuting behavior? A case study of Xiamen, China

Although there is a growing body of literature on the commuting pattern of rural migrants in China, few studies have examined the diversity in commuting behavior among workers with different occupations. The present research used the 2015 Xiamen household travel survey to examine commuting distances and commuting times of distinctive types of workers in the city. The results reveal differences in commuting behaviors among distinctive socioeconomic groups, namely blue-collar, pink-collar, or white-collar local or migrant workers. For local residents, blue-collar workers have the longest commute distance, while pink-collar workers have the shortest commute distance. Migrant workers—for both blue-collar and pink-collar—in general commute over shorter distances than local workers to reach their workplaces. However, planning practices have attempted to demolish their affordable rental housing in urban villages, which will increase their commuting times and costs and exacerbate sociospatial inequality. These findings can be of practical use when offering alternative housing for migrants in urban redevelopment.

Behavior of a constrained particle on superintegrability of the two-dimensional complex Cayley–Klein space and its thermodynamic properties

In this paper, we study the motion of a particle on a family of superintegrable Hamiltonians of the unitary groups in Cayley–Klein space. This possibility is provided through the general commutator relations between generators from its respective group. Hence, by converting coordinates from Cartesian space to Eulerian parameterization, the obtained metric in terms of the new coordinates is equal to the same Lagrangian of geodesic motion. On the other hand, by reducing the SUκ1κ2(3) group manifold to the SUκ1κ2(3)∕SUκ1(2)≃Ω5 quotient space and considering the three Fourier transformations, the particle is reduced to two-dimensional space (Ω2=S2,H2ordS1+1) depending on the contraction parameter κ. Then with overlapping the reduced coordinates in the Eulerian parameterization with the canonical coordinates, we incorporate them into the Lagrangian. Therefore, we find three constant integrals of motion from the vector fields and we construct the superintegrable Hamiltonian. However, we obtain the wave function and the energy spectrum of the system by separating the variables and their solutions. Finally, by applying the resulting energy, for the two special cases of the produced topological space, we investigate and compare their thermodynamic properties.

A Commingle between the Contractive Conditions of Type Jungck and a General Weak Commutativity Concept

In this work, we prove a common fixed point theorem of type Jungck under a generalized definition of weak commutativity and a well-known contractive inequality by commingling both conditions in the proof. Some open questions are also indicated and intimately connected (or not?) to the metric to be used.

Thermodynamic properties of quantum models based on the complex unitary Cayley-Klein groups

In this work, the goal is to reach the thermodynamics properties produced by a family of the integrable Hamiltonians of the unitary groups of rank one in the Cayley-Klein space. In fact, this makes it possible through the general commutator relations between their generators of the desired Cayley-Klein group under investigation. On the other hand, by converting the coordinates to the Euler parameterization, the metric obtained from the Casimir is rewritten in terms of these coordinates, which is equal to the same the Lagrangian of the geodesic motion of the corresponding space. By matching coordinates, Lagrangian is written in terms of canonical momenta, and so the Hamiltonian can be obtained in two forms: one for a free particle and another for an involved particle with the integral potential. Hence, by solving the Hamiltonian of each of the two states in a different way(NU and SUSY QM methods), the quantum model for its corresponding system is shown in terms of the contraction parameter (κ1). Finally, with finding eigenvalues for each of these two systems, their thermodynamic properties are discussed with changing two parameters λ and δ, respectively. In our study, one can only see a phase transition in the heat capacity diagram at critical point τ0. In other words, it can be stated that a phase transition of the second type possible occurs for free particle in high temperature. Also, other results are reported in the end.

Stress-tensor commutators in conformal field theories near the lightcone

Starting with the general stress-tensor commutation relations consistent with the Poincar\'e algebra in local quantum field theory, we impose the tracelessness condition and focus on the dominating contributions in the lightcone limit. It is shown that, under a certain assumption on the Schwinger term, a Virasoro-algebra-like structure emerges near the lightcone in $d>2$ conformal field theories.

Two-weight commutator estimates: general multi-parameter framework

We provide an explicit technical framework for proving very general two-weight commutator estimates in arbitrary parameters. The aim is to both clarify existing literature, which often explicitly focuses on two parameters only, and to extend very recent results to the full generality of arbitrary parameters. More specifically, we study two-weight commutator estimates -- Bloom type estimates -- in the multi-parameter setting involving weighted product BMO and little BMO spaces, and their combinations.

Bessel sequences, wavelet frames, duals and extensions

From the perspectives of duality and extensions, Gabor frames and wavelet frames have contrasting behaviour. Our chief concern here is about duality. Canonical duals of wavelet frames may not be wavelet frames, whereas canonical duals of Gabor frames are Gabor frames. Keeping these in view, we give several constructions of wavelet frames with wavelet canonical duals. For this, a simple characterisation of Bessel sequences and a general commutativity result are given, the former also leading naturally to some extension results.

Weighted inequalities for a general commutator associated to a singular integral operator satisfying a variant of Hörmander’s condition

In this paper, weighted inequalities for a certain general commutator associated to a singular integral operator satisfying a variant of Ho¨ rmander’s condition on Lebesgue spaces are obtained. To do this, some weighted sharp maximal function inequalities for the commutator are proved.

Generalized Ordered Weighted Reference Dependent Utility Aggregation Operators and Their Applications to Group Decision-Making

To quantify the influence of decision makers’ psychological factors on the group decision process, this paper develops a new class of aggregation operators based on reference-dependent utility functions (RUs) in multi-attribute group decision analysis. RUs include S-shaped RU and non-S-shaped RU. Each RU affords a framework where the psychological factors explicitly enter the decision problem via the basic utility function, reference point and loss aversion coefficient. Under the general framework, we derive a generalized ordered weighted S-shaped RU proportional averaging (GOSP) operator and a generalized ordered weighted non-S-shaped RU proportional averaging (GONSP) operator, respectively. The GOSP operator implies the risk attitude of the DM for relative losses is risk-seeking, while GONSP operator indicates the risk attitude in this case is risk-averse. As a special case, GONSP operator can degenerate into GOWPA operator which means that the attitude of the DM is risk-neutral. Each operator satisfies the desirable properties of general operator, i.e., monotonicity, commutativity, idempotency and boundedness. Furthermore, we consider hyperbolic absolute risk aversion (HARA) function as the basic utility function, and define an S-shaped HARA and a non-S-shaped HARA utility functions. Based on the two new RUs, we propose GOSP–HARA operator and GONSP–HARA operator. Every operator covers many existing aggregation operators. To ascertain weights of such operators, the paper builds an attribute-deviation weight model and a DMs-deviation weight model. Based on these RU operators and weight models, an approach is addressed for solving multiple attribute group decision-making problem. At last, an example is provided to show the feasible of our approach.

Weak electromagnetic field admitting integrability in Kerr-NUT-(A)dS spacetimes

We investigate properties of higher-dimensional generally rotating black-hole spacetimes, so called Kerr-NUT-(A)dS spacetimes, as well as a family of related spaces which share the same explicit and hidden symmetries. In these spaces, we study a particle motion in the presence of a weak electromagnetic field and compare it with its operator analogies. First, we find general commutativity conditions for classical observables and for their operator counterparts, then we investigate a fulfillment of these conditions in the Kerr-NUT-(A)dS and related spaces. We find the most general form of the weak electromagnetic field compatible with the complete integrability of the particle motion and the comutativity of the field operators. For such a field we solve the charged Hamilton-Jacobi and Klein-Gordon equations by separation of variables.

Special-case closed form of the Baker–Campbell–Hausdorff formula

The Baker–Campbell–Hausdorff formula is a general result for the quantity , where X and Y are not necessarily commuting. For completely general commutation relations between X and Y, (the free Lie algebra), the general result is somewhat unwieldy. However in specific physics applications the commutator , while non-zero, might often be relatively simple, which sometimes leads to explicit closed form results. We consider the special case , and show that in this case the general result reduces to Z ( X , Y ) = ln ( e X e Y ) = X + Y + f ( u , v ) [ X , Y ] . ?>Furthermore we explicitly evaluate the symmetric function , demonstrating that f ( u , v ) = ( u − v ) e u + v − ( ue u − ve v ) uv ( e u − e v ) , ?>and relate this to previously known results. For instance this result includes, but is considerably more general than, results obtained from either the Heisenberg commutator or the creation-destruction commutator .

An Effect System for Algebraic Effects and Handlers

We present an effect system for core Eff, a simplified variant of Eff, which is an ML-style programming language with first-class algebraic effects and handlers. We define an expressive effect system and prove safety of operational semantics with respect to it. Then we give a domain-theoretic denotational semantics of core Eff, using Pitts's theory of minimal invariant relations, and prove it adequate. We use this fact to develop tools for finding useful contextual equivalences, including an induction principle. To demonstrate their usefulness, we use these tools to derive the usual equations for mutable state, including a general commutativity law for computations using non-interfering references. We have formalized the effect system, the operational semantics, and the safety theorem in Twelf.

Design and aerodynamic analysis of a twin-engine commuter aircraft

The present paper deals with the preliminary design of a new general aviation Commuter 11 seat aircraft. The commuter aircraft market is today characterized by very few new models and the majority of aircraft in operation belonging to this category are older than 35 years. Tecnam Aircraft Industries and the Department of Industrial Engineering (DII) of the University of Naples “Federico II” have been deeply involved in the design of a new commuter aircraft that should be introduced in the market with very good opportunities of success. This paper aims to provide some guidelines on the conceptual design of this new twin-engine commuter aircraft. Aircraft configuration and cabin layout choices are shown and compared to similar solutions adopted by main competitors. The aerodynamic analyses are focused on some particular effects such as the wing–fuselage interference and the nacelle lift contribution and their effect on wing span loading. The aerodynamic analyses have been also essential to validate the preliminary estimation of aircraft stability and control derivatives (both longitudinal and lateral–directional) and to lead to a right sizing of tail surfaces. These analyses have been carried out through the use of a 3-D panel code. Finally some preliminary wind tunnel test results are presented.

The Yoga of Commutators: Further Applications

In the present paper, we describe some recent applications of localization methods to the study of commutators in the groups of points of algebraic and algebraic-like groups, such as GL(n,R), Bak’s unitary groups GU(2n,R, Λ), and Chevalley groups G(Φ,R). In particular, we announce the multiple relative commutator formula and the general multiple relative commutator formula, as well as results on the bounded width of relative commutators in the elementary generators. We also state some of the intermediate results, as well as some corollaries of these results. At the end of the paper we attach an updated list of unsolved problems in the field.

Commuter Cyclist Travel Behavior

The study reported in this paper examined commuter cyclist travel behavior specifically in response to changes in weather. An investigation into how bicyclists made their day-to-day riding decisions provided insights into the factors that guided their behavior in adverse weather. Disaggregate travel data collected from an in-depth survey were analyzed. Examination of general commuter cyclist travel behavior led to the identification of differences on the basis of riding frequency. Weather conditions were found to be a paramount factor in a commuter's riding decisions. Further survey results were analyzed to gain insight into the influence of end-of-trip facilities and to quantify whether riders who had access to such facilities were less sensitive to changes in weather. More than half of the respondents indicated that these facilities were important, in that they encouraged the respondents to ride to work when the weather was not favorable. Given the variability in day-to-day ridership, commuter riders were expected to alternate modes when faced with adverse weather. The modal shift of commuter riders was analyzed with a logistic regression model. When the model was used to predict the probability of a shift to private transport (e.g., drive alone, get a lift from someone else, use a motorcycle or motor scooter), it correctly predicted nearly 80% of the cases. The implications of the results for government policies and strategies that seek to increase commuter cycling in urban areas are discussed.

Differential operators commuting in the principal part

We consider commuting differential operators with two independent variables of general form and obtain general necessary commutativity conditions for low-order operators. We show that these conditions allow classifying commuting pairs of operators whose coefficients are linear functions of the independent variables.