scholarly journals Expected values of statistics on permutation tableaux

2007 ◽  
Vol DMTCS Proceedings vol. AH,... (Proceedings) ◽  
Author(s):  
Sylvie Corteel ◽  
Pawel Hitczenko
Keyword(s):  
Simple Proof ◽  
Statistical Physics ◽  
Unified Approach ◽  
Research Activity ◽  
Considerable Research ◽  
Totally Positive ◽  
International Audience ◽  
Expected Values

International audience Permutation tableaux are new objects that were introduced by Postnikov in the context of enumeration of the totally positive Grassmannian cells. They are known to be in bijection with permutations and recently, they have been connected to PASEP model used in statistical physics. Properties of permutation tableaux became a focus of a considerable research activity. In this paper we study properties of basic statistics defined on permutation tableaux. We present a simple and unified approach based on probabilistic techniques and use it to compute the expected values of basic statistics defined on permutation tableaux. We also provide a non―bijective and very simple proof that there are n! permutation tableaux of length n.

EV – Challenges In Going Electric

2018 ◽  
Author(s):  
Umanand L
Keyword(s):  
Mass Transport ◽  
Electric Vehicle ◽  
Electric Vehicles ◽  
Hybrid Electric Vehicles ◽  
Research Activity ◽  
Considerable Research ◽  
Hybrid Electric

This article presents a frank and open opinion on the challenges that will be faced in moving towards an electric mass transport ecosystem. World over there is considerable research activity on electric vehicles and hybrid electric vehicles. There seems to be a global effort to move from an ICE driven ecosystem to electric vehicle ecosystem. There is no simple means to make this transition. This road is filled with hurdles and challenges. This paper poses and discusses these challenges and possible solutions for enabling EVs.

Chapter 22. Connections to Statistical Physics

2021 ◽  
Author(s):  
Fabrizio Altarelli ◽  
Rémi Monasson ◽  
Guilhem Semerjian ◽  
Francesco Zamponi
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Statistical Mechanics ◽  
Cost Function ◽  
Computer Science ◽  
Statistical Physics ◽  
Energy Landscape ◽  
Research Activity ◽  
Detailed Picture ◽  
Intense Research

This chapter surveys a part of the intense research activity that has been devoted by theoretical physicists to the study of randomly generated k-SAT instances. It can be at first sight surprising that there is a connection between physics and computer science. However low-temperature statistical mechanics concerns precisely the behaviour of the low-lying configurations of an energy landscape, in other words the optimization of a cost function. Moreover the ensemble of random k-SAT instances exhibit phase transitions, a phenomenon mostly studied in physics (think for instance at the transition between liquid and gaseous water). Besides the introduction of general concepts of statistical mechanics and their translations in computer science language, the chapter presents results on the location of the satisfiability transition, the detailed picture of the satisfiable regime and the various phase transitions it undergoes, and algorithmic issues for random k-SAT instances.

Piston Pump Noise Attenuation Through Modification of Piston Travel Trajectory

2010 ◽  
Author(s):  
Viral S. Mehta ◽  
Noah D. Manring
Keyword(s):  
High Pressure ◽  
Mobile Applications ◽  
Noise Attenuation ◽  
Dynamic Flow ◽  
Research Activity ◽  
Dynamic Component ◽  
Flow Ripple ◽  
Flow Component ◽  
High Speeds ◽  
Considerable Research

Piston pumps are widely used in industrial and mobile applications to transmit power. These pumps emit loud and objectionable noise when operated at high pressure and high speeds. It is generally accepted that large amplitude of flow ripple causes pumps to produce unacceptable noise level. The flow ripple could be thought of composed of two components — a kinematic component resulting out of periodic nature of flow and a dynamic component resulting due to compression and decompression of fluid. There has been considerable research activity to reduce the noise induced by the dynamic component however very little is done to attenuate the noise generated due to the periodic nature of flow. This research investigated one method to reduce noise associated with kinematic component for axial and radial type piston pumps. A theoretical analysis is presented deriving the equations defining the motion of pistons on their regular trajectory as well as their modified trajectory. It is shown here that by altering the trajectory of the piston travel the amplitude of the kinematic flow component could be reduced by up to 85% in some conditions. While effectiveness of the techniques aimed at reducing the dynamic flow component are speed and pressure dependent, the techniques presented here work with same effectiveness throughout the entire spectrum of speed and pressure towards reducing the noise.

scholarly journals A note on domino treewidth

1999 ◽  
Vol Vol. 3 no. 4 ◽  
Author(s):  
Hans L. Bodlaender
Keyword(s):  
Lower Bound ◽  
Simple Proof ◽  
Maximum Degree ◽  
International Audience

International audience In [DO95], Ding and Oporowski proved that for every k, and d, there exists a constant c_k,d, such that every graph with treewidth at most k and maximum degree at most d has domino treewidth at most c_k,d. This note gives a new simple proof of this fact, with a better bound for c_k,d, namely (9k+7)d(d+1) -1. It is also shown that a lower bound of Ω (kd) holds: there are graphs with domino treewidth at least 1/12 × kd-1, treewidth at most k, and maximum degree at most d, for many values k and d. The domino treewidth of a tree is at most its maximum degree.

scholarly journals Arrangements of equal minors in the positive Grassmannian

2014 ◽  
Vol DMTCS Proceedings vol. AT,... (Proceedings) ◽  
Author(s):  
Miriam Farber ◽  
Alexander Postnikov
Keyword(s):  
Cluster Algebra ◽  
The Other ◽  
Eulerian Number ◽  
Other Hand ◽  
Totally Positive ◽  
Positive Matrices ◽  
International Audience ◽  
Separated Sets ◽  
Weakly Separated Sets ◽  
Totally Positive Matrices

International audience We discuss arrangements of equal minors in totally positive matrices. More precisely, we would like to investigate the structure of possible equalities and inequalities between the minors. We show that arrangements of equals minors of largest value are in bijection with <i>sorted sets</i>, which earlier appeared in the context of <i>alcoved polytopes</i> and Gröbner bases. Maximal arrangements of this form correspond to simplices of the alcoved triangulation of the hypersimplex; and the number of such arrangements equals the <i>Eulerian number</i>. On the other hand, we conjecture and prove in many cases that arrangements of equal minors of smallest value are exactly the <i>weakly separated sets</i>. Weakly separated sets, originally introduced by Leclerc and Zelevinsky, are closely related to the \textitpositive Grassmannian and the associated <i>cluster algebra</i>.

Developmental Phonological Disorders

1994 ◽  
Vol 3 (3) ◽  
pp. 26-28 ◽  
Author(s):  
Lawrence D. Shriberg
Keyword(s):  
Social Sciences ◽  
Clinical Research ◽  
21St Century ◽  
Classification System ◽  
Laboratory Research ◽  
Research Groups ◽  
Research Culture ◽  
Research Activity ◽  
Phonological Disorders ◽  
Considerable Research

I have argued that notwithstanding considerable research activity in developmental phonological disorders, the basic questions remain unanswered. I have proposed that a central problem with the research culture in child phonology is that it includes too little cross-laboratory collaboration of the type seen when significant breakthroughs are reported in other biological and social sciences. Finally, I have suggested the need for a shared classification system for developmental phonological disorders—to promote cross-laboratory research, as well as to strengthen the efforts of individual clinical research groups. As stressed by one of my teachers, Ralph Shelton, collaboration is a cornerstone of scholarship. I am optimistic that our discipline will evolve toward a productive 21st century marked by vital, collaborative scholarship.

scholarly journals A variant of the Recoil Growth algorithm to generate multi-polymer systems

2008 ◽  
Vol DMTCS Proceedings vol. AI,... (Proceedings) ◽  
Author(s):  
Florian Simatos
Keyword(s):  
Lower Bound ◽  
Simple Proof ◽  
Efficient Algorithm ◽  
Computational Cost ◽  
Polymer System ◽  
Specific Class ◽  
Trade Off ◽  
Polymer Systems ◽  
Original Algorithm ◽  
International Audience

International audience The Recoil Growth algorithm, proposed in 1999 by Consta $\textit{et al.}$, is one of the most efficient algorithm available in the literature to sample from a multi-polymer system. Such problems are closely related to the generation of self-avoiding paths. In this paper, we study a variant of the original Recoil Growth algorithm, where we constrain the generation of a new polymer to take place on a specific class of graphs. This makes it possible to make a fine trade-off between computational cost and success rate. We moreover give a simple proof for a lower bound on the irreducibility of this new algorithm, which applies to the original algorithm as well.

An Involvement-Based Framework For The Study Of Environmentally Concerned Consumers

2001 ◽  
Vol 7 (2) ◽  
pp. 1-19 ◽  
Author(s):  
Peter H Bloch ◽  
Subhabrata Bobby Banjeree
Keyword(s):  
Public Policy ◽  
Conceptual Framework ◽  
Environmental Concern ◽  
Consumer Involvement ◽  
Policy Implications ◽  
Research Interest ◽  
Research Activity ◽  
Policy Makers ◽  
Considerable Research ◽  
Societal Interest

AbstractDuring the 1970's there was considerable research interest in environmentally concerned consumers. Mirroring societal interest levels, such research waned in the 1980's. Today, this topic has regained its relevance, however. Marketers actively target these consumers and public policy makers strive to increase their numbers. In addition, research activity pertaining to these consumers has increased noticeably in recent years. Despite the increased attention to environmental concern, a viable conceptual framework for its study is still lacking. A review of past work indicates that environmental concern has been variously treated as a group of behaviours, attitudes, affect, and intentions. In order to clarify the construct and provide needed theory for its study, a framework of environmental concern is provided here. This framework is drawn from existing work on environmental concern and research pertaining to consumer involvement. The nature, outcomes, and sources for environmental concern are discussed along with marketing and public policy implications.

Simple derivations of the invariance relations and their applications

1982 ◽  
Vol 19 (1) ◽  
pp. 183-194 ◽  
Author(s):  
Masakiyo Miyazawa
Keyword(s):  
General Formula ◽  
Waiting Time ◽  
Simple Proof ◽  
Inversion Formula ◽  
Point Processes ◽  
Queueing Models ◽  
Unified Approach ◽  
Little's Formula

In the literature, various methods have been studied for obtaining invariance relations, for example, L = λW (Little's formula), in queueing models. Recently, it has become known that the theory of point processes provides a unified approach to them (cf. Franken (1976), König et al. (1978), Miyazawa (1979)). This paper is also based on that theory, and we derive a general formula from the inversion formula of point processes. It is shown that this leads to a simple proof for invariance relations in G/G/c queues. Using these results, we discuss a condition for the distribution of the waiting time vector of a G/G/c queue to be identical with that of an M/G/c queue.

scholarly journals A note on Hardy's theorem

2017 ◽  
Vol Volume 39 ◽  
Author(s):  
Usha K. Sangale
Keyword(s):  
Zeta Function ◽  
Simple Proof ◽  
Riemann Zeta Function ◽  
Hardy’S Theorem ◽  
The Riemann Zeta Function ◽  
International Audience ◽  
Riemann Zeta ◽  
Complex Zeros

International audience Hardy's theorem for the Riemann zeta-function ζ(s) says that it admits infinitely many complex zeros on the line (s) = 1 2. In this note, we give a simple proof of this statement which, to the best of our knowledge, is new.

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