نتایج جستجو برای: randic index

تعداد نتایج: 396091  

Journal: :Discrete Applied Mathematics 2013
Sandi Klavzar Mohammad J. Nadjafi-Arani

Let (G,w) be a network, that is, a graph G = (V (G), E(G)) together with the weight function w : E(G) → R. The Szeged index Sz(G,w) of the network (G,w) is introduced and proved that Sz(G,w) ≥ W (G,w) holds for any connected network where W (G,w) is the Wiener index of (G,w). Moreover, equality holds if and only if (G,w) is a block network in which w is constant on each of its blocks. Analogous...

Journal: :تحقیقات نظام سلامت 0
حبیب اله دهقان مربی، گروه مهندسی بهداشت حرفه ای، دانشکده بهداشت، دانشگاه علوم پزشکی اصفهان، اصفهان، ایران احسان اله حبیبی دانشیار، گروه مهندسی بهداشت حرفه ای، دانشکده بهداشت، دانشگاه علوم پزشکی اصفهان، اصفهان، ایران بهنام خدارحمی دانشجوی کارشناسی ارشد، کمیته تحقیقات دانشجویی، گروه مهندسی بهداشت حرفه ای، دانشکده بهداشت، دانشگاه علوم پزشکی اصفهان، اصفهان، ایران حسینعلی یوسفی مربی، گروه مهندسی بهداشت حرفه ای، دانشکده بهداشت، دانشگاه علوم پزشکی اصفهان، اصفهان، ایران اکبر حسن زاده مربی، مرکز تحقیقات امنیت غذایی، گروه آمار زیستی و اپیدمیولوژی، دانشکده بهداشت، دانشگاه علوم پزشکی اصفهان، اصفهان، ایران

background: heat stress is a common and usual problem in industries. several indices, including wet bulb globe temperature (wbgt), are used to evaluate heat stress. however, wbgt index has limitations such as high cost and response time. it is not thus suitable as a screening tool. heat strain scoring index (hssi) is also an observational-judgmental technique that has been developed for primary...

Journal: :transactions on combinatorics 2012
wai chee shiu kwong harris

let $g=(v,e)$ be a connected simple graph. a labeling $f:v to z_2$ induces two edge labelings $f^+, f^*: e to z_2$ defined by $f^+(xy) = f(x)+f(y)$ and $f^*(xy) = f(x)f(y)$ for each $xy in e$. for $i in z_2$, let $v_f(i) = |f^{-1}(i)|$, $e_{f^+}(i) = |(f^{+})^{-1}(i)|$ and $e_{f^*}(i) = |(f^*)^{-1}(i)|$. a labeling $f$ is called friendly if $|v_f(1)-v_f(0)| le 1$. for a friendly labeling $f$ of...

Journal: :iranian journal of mathematical chemistry 2010
a. t. balaban p. v. khadikar s. aziz

the padmakar-ivan (pi) index is a first-generation topological index (ti) based on sums overall edges between numbers of edges closer to one endpoint and numbers of edges closer to theother endpoint. edges at equal distances from the two endpoints are ignored. an analogousdefinition is valid for the wiener index w, with the difference that sums are replaced byproducts. a few other tis are discu...

Journal: :iranian journal of mathematical chemistry 2010
k. ch. das i. gutman b. furtula

the concept of geometric-arithmetic indices (ga) was put forward in chemical graph theoryvery recently. in spite of this, several works have already appeared dealing with these indices.in this paper we present lower and upper bounds on the second geometric-arithmetic index(ga2) and characterize the extremal graphs. moreover, we establish nordhaus-gaddum-typeresults for ga2.

Journal: :iranian journal of mathematical chemistry 2010
k. ch. das i. gutman b. furtula

continuing the work k. c. das, i. gutman, b. furtula, on second geometric-arithmetic indexof graphs, iran. j. math chem., 1(2) (2010) 17-28, in this paper we present lower and upperbounds on the third geometric-arithmetic index ga3 and characterize the extremal graphs.moreover, we give nordhaus-gaddum-type result for ga3.

Journal: Current Medical Mycology 2018

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