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Values K (value + k)
Selected AbstractsKinetics of the reactions of OH with 3-methyl-2-cyclohexen-1-one and 3,5,5-trimethyl-2-cyclohexen-1-one under simulated atmospheric conditionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 1 2002James B. McQuaid Relative rate coefficients for the reactions of OH with 3-methyl-2-cyclohexen-1-one and 3,5,5-trimethyl-2-cyclohexen-1-one have been determined at 298 K and atmospheric pressure by the relative rate technique. OH radicals were generated by the photolysis of methyl nitrite in synthetic air mixtures containing ppm levels of nitric oxide together with the test and reference substrates. The concentrations of the test and reference substrates were followed by gas chromatography. Based on the value k(OH + cyclohexene) = (6.77 ± 1.35) × 10,11 cm3 molecule,1 s,1, rate coefficients for k(OH + 3-methyl-2-cyclohexen-1-one) = (3.1 ± 1.0) × 10,11 and k(OH + 3,5,5-trimethyl-2-cyclohexen-1-one) = (2.4 ± 0.7) × 10,11 cm3 molecule,1 s,1 were determined. To test the system we also measured k(OH + isoprene) = (1.11 ± 0.23) × 10,10 cm3 molecule,1 s,1, relative to the value k(OH + (E)-2-butene) = (6.4 ± 1.28) × 10,11 cm3 molecule,1 s,1. The results are discussed in terms of structure,activity relationships, and the reactivities of cyclic ketones formed in the photo-oxidation of monoterpene are estimated. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 7,11, 2002 [source] The effect of truck traffic and road water content on sediment delivery from unpaved forest roadsHYDROLOGICAL PROCESSES, Issue 8 2006Gary J. Sheridan Abstract A study investigated the effect of truck-traffic intensity and road water-content on the quality of runoff water from unsealed forest roads. Three sections of a gravel-surfaced forest road were instrumented and exposed to low and high levels of truck traffic during wet winter conditions and dry summer conditions between July 2001 and December 2002. Rainfall, runoff, road moisture, and traffic were measured continuously, and suspended and bedload sediments were integrated measurements over 2-week site-service intervals. The median suspended sediment concentration from the three road segments under low truck-traffic conditions (less than nine return truck passes prior to a storm) was 269 mg l,1, increasing 2·7-fold to a median of 725 mg l,1 under high truck-traffic conditions (greater than or equal to nine return truck passes prior to a storm). These concentrations, and increases due to traffic, are substantially less than most previously reported values. When these data are expressed as modified universal soil loss equation (MUSLE) erodibility values K, accounting for differences in rainfall energy, site characteristics and runoff, high traffic resulted in a road surface that was four times more erodible than the same road under low traffic conditions. Using multiple regression, traffic explained 36% of the variation in MUSLE erodibility, whereas road water content was not significant in the model. There was little difference in the erodibility of the road when trafficked in low water-content compared with high water-content conditions (MUSLE K values of 0·0084 versus 0·0080 respectively). This study shows that, for a good quality well-maintained gravel forest road, the level of truck traffic affects the sediment concentration of water discharging from the road, whereas the water content of the road at the time of that traffic does not (note that traffic is not allowed during runoff events in Victoria). These conclusions are conditional upon the road being adequately maintained so that trafficking does not compromise the lateral drainage of the road profile. Copyright © 2005 John Wiley & Sons, Ltd. [source] Semigroup approach for identification of the unknown diffusion coefficient in a quasi-linear parabolic equationMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 11 2007Ali Demir Abstract This article presents a semigroup approach for the mathematical analysis of the inverse coefficient problems of identifying the unknown coefficient k(u(x,t)) in the quasi-linear parabolic equation ut(x,t)=(k(u(x,t))ux(x,t))x, with Dirichlet boundary conditions u(0,t)=,0, u(1,t)=,1. The main purpose of this paper is to investigate the distinguishability of the input,output mappings ,[,]:,, ,C1[0,T], ,[,]:,,,C1[0,T] via semigroup theory. In this paper, it is shown that if the null space of the semigroup T(t) consists of only zero function, then the input,output mappings ,[,] and ,[,] have the distinguishability property. It is also shown that the types of the boundary conditions and the region on which the problem is defined play an important role in the distinguishability property of these mappings. Moreover, under the light of measured output data (boundary observations) f(t):=k(u(0,t))ux(0,t) or/and h(t):=k(u(1,t))ux(1,t), the values k(,0) and k(,1) of the unknown diffusion coefficient k(u(x,t)) at (x,t)=(0,0) and (x,t)=(1,0), respectively, can be determined explicitly. In addition to these, the values ku(,0) and ku(,1) of the unknown coefficient k(u(x,t)) at (x,t)=(0,0) and (x,t)=(1,0), respectively, are also determined via the input data. Furthermore, it is shown that measured output dataf(t) and h(t) can be determined analytically by an integral representation. Hence the input,output mappings ,[,]:,,, C1[0,T], ,[,]:,,,C1[0,T] are given explicitly in terms of the semigroup. Copyright © 2007 John Wiley & Sons, Ltd. [source] Rainbow trees in graphs and generalized connectivityNETWORKS: AN INTERNATIONAL JOURNAL, Issue 4 2010Gary Chartrand Abstract An edge-colored tree T is a rainbow tree if no two edges of T are assigned the same color. Let G be a nontrivial connected graph of order n and let k be an integer with 2 , k , n. A k -rainbow coloring of G is an edge coloring of G having the property that for every set S of k vertices of G, there exists a rainbow tree T in G such that S , V(T). The minimum number of colors needed in a k -rainbow coloring of G is the k -rainbow index of G. For every two integers k and n , 3 with 3 , k , n, the k -rainbow index of a unicyclic graph of order n is determined. For a set S of vertices in a connected graph G of order n, a collection {T1,T2,,,T,} of trees in G is said to be internally disjoint connecting S if these trees are pairwise edge-disjoint and V(Ti) , V(Tj) = S for every pair i,j of distinct integers with 1 , i,j , ,. For an integer k with 2 , k , n, the k -connectivity ,k(G) of G is the greatest positive integer , for which G contains at least , internally disjoint trees connecting S for every set S of k vertices of G. It is shown that ,k(Kn)=n,,k/2, for every pair k,n of integers with 2 , k , n. For a nontrivial connected graph G of order n and for integers k and , with 2 , k , n and 1 , , , ,k(G), the (k,,)-rainbow index rxk,,(G) of G is the minimum number of colors needed in an edge coloring of G such that G contains at least , internally disjoint rainbow trees connecting S for every set S of k vertices of G. The numbers rxk,,(Kn) are determined for all possible values k and , when n , 6. It is also shown that for , , {1, 2}, rx3,,(Kn) = 3 for all n , 6. © 2009 Wiley Periodicals, Inc. NETWORKS, 2010 [source] | ||||||||||