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N Systems (n + system)
Selected AbstractsPhase Relations of the Ag,Ga,N System.CHEMINFORM, Issue 20 2007Y. Zhang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Sc3AlN , A New PerovskiteEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2008Carina Höglund Abstract Sc3AlN with perovskite structure has been synthesized as the first ternary phase in the Sc,Al,N system. Magnetron sputter epitaxy at 650 °C was used to grow single-crystal, stoichiometric Sc3AlN(111) thin films onto MgO(111) substrates with ScN(111) seed layers as shown by elastic recoil detection analysis, X-ray diffraction, and transmission electron microscopy. The Sc3AlN phase has a lattice parameter of 4.40 Å, which is in good agreement with the theoretically predicted 4.42 Å. Comparisons of total formation energies show that Sc3AlN is thermodynamically stable with respect to all known binary compounds. Sc3AlN(111) films of 1.75 µm thickness exhibit a nanoindentation hardness of 14.2 GPa, an elastic modulus of 249 GPa, and a room-temperature electrical resistivity of 41.2 µ, cm. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Comparative Studies on Mo,Cr,N and Al,Cr,N Coatings Obtained by PVD Dual Magnetron SputteringPLASMA PROCESSES AND POLYMERS, Issue S1 2009Yacine Benlatreche Abstract Recently, several studies have shown that the addition of a secondary element likes Al, Si, etc. to nitride and carbide binary systems such as Ti,N and Cr,N improved their structural and mechanical properties and also their thermal stability. In this study, we realized a comparison between the effects of aluminium or molybdenum addition on the properties of the Cr,N system. The (Cr,Al)N and (Cr,Mo)N films were deposited by RF dual magnetron sputtering. To control the aluminium and molybdenum contents in (Cr,Al)N and in (Cr,Mo)N films, respectively, we modified the Cr, Al and Mo target bias. The structural, morphological and composition analyses of the deposited films were carried out using X-ray diffraction (XRD) and SEM equipped with an energy dispersive spectroscopy (EDS) microanalysis. The variation of the residual stresses with the Al and Mo contents has been studied using the Newton's rings method. The obtained Al contents in (Cr,Al)N deposited films varied between 0 and 51,at.% while the Mo contents in (Cr,Mo)N layers varied between 0 and 42,at.%. A morphological change from amorphous to columnar films has been observed with the addition of Al in the case of (Cr,Al)N coatings, while all the (Cr,Mo)N films presented a columnar structure. The residual stresses of the (Cr,Mo)N coatings are higher than the (Cr,Al)N ones but they exhibited a similar behaviour for both coatings. [source] Aging properties of the residual life length of k -out-of- n systems with independent but non-identical componentsAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 2 2004Xiaohu Li Abstract The k -out-of- n structure is a very popular type of redundancy in fault-tolerant systems, it has founded wide applications in industrial and military systems during the past several decades. This paper will investigate the residual life length of a k -out-of- n system with independent (not necessarily identical) components, given that the (n,k)th failure has occurred at time t,0. Behaviour of PF2, IFR, DRHR, DMRL, NBU(2) and NBUC classes of life distributions are derived in terms of the monotonicity of the residual life given the time of the (n,k)th failure. Copyright © 2004 John Wiley & Sons, Ltd. [source] On the application and extension of system signatures in engineering reliabilityNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 4 2008Jorge Navarro Abstract Following a review of the basic ideas in structural reliability, including signature-based representation and preservation theorems for systems whose components have independent and identically distributed (i.i.d.) lifetimes, extensions that apply to the comparison of coherent systems of different sizes, and stochastic mixtures of them, are obtained. It is then shown that these results may be extended to vectors of exchangeable random lifetimes. In particular, for arbitrary systems of sizes m < n with exchangeable component lifetimes, it is shown that the distribution of an m -component system's lifetime can be written as a mixture of the distributions of k -out-of- n systems. When the system has n components, the vector of coefficients in this mixture representation is precisely the signature of the system defined in Samaniego, IEEE Trans Reliabil R,34 (1985) 69,72. These mixture representations are then used to obtain new stochastic ordering properties for coherent or mixed systems of different sizes. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008 [source] A branch and bound algorithm for computing optimal replacement policies in consecutive k -out-of- n -systemsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 3 2002James Flynn Abstract This paper presents a branch and bound algorithm for computing optimal replacement policies in a discrete-time, infinite-horizon, dynamic programming model of a binary coherent system with n statistically independent components, and then specializes the algorithm to consecutive k -out-of- n systems. The objective is to minimize the long-run expected average undiscounted cost per period. (Costs arise when the system fails and when failed components are replaced.) An earlier paper established the optimality of following a critical component policy (CCP), i.e., a policy specified by a critical component set and the rule: Replace a component if and only if it is failed and in the critical component set. Computing an optimal CCP is a optimization problem with n binary variables and a nonlinear objective function. Our branch and bound algorithm for solving this problem has memory storage requirement O(n) for consecutive k -out-of- n systems. Extensive computational experiments on such systems involving over 350,000 test problems with n ranging from 10 to 150 find this algorithm to be effective when n , 40 or k is near n. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 288,302, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10017 [source] Generalized mixtures in reliability modelling: Applications to the construction of bathtub shaped hazard models and the study of systemsAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 3 2009Jorge Navarro Abstract In this paper, we obtain and discuss some general properties of hazard rate (HR) functions constructed via generalized mixtures of two members. These results are applied to determine the shape of generalized mixtures of an increasing hazard rate (IHR) model and an exponential model. In addition, we note that these kind of generalized mixtures can be used to construct bathtub-shaped HR models. As examples, we study in detail two cases: when the IHR model chosen is a linear HR function and when the IHR model is the extended exponential-geometric distribution. Finally, we apply the results and show the utility of generalized mixtures in determining the shape of the HR function of different systems, such as mixed systems or consecutive k -out-of- n systems. Copyright © 2008 John Wiley & Sons, Ltd. [source] Aging properties of the residual life length of k -out-of- n systems with independent but non-identical componentsAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 2 2004Xiaohu Li Abstract The k -out-of- n structure is a very popular type of redundancy in fault-tolerant systems, it has founded wide applications in industrial and military systems during the past several decades. This paper will investigate the residual life length of a k -out-of- n system with independent (not necessarily identical) components, given that the (n,k)th failure has occurred at time t,0. Behaviour of PF2, IFR, DRHR, DMRL, NBU(2) and NBUC classes of life distributions are derived in terms of the monotonicity of the residual life given the time of the (n,k)th failure. Copyright © 2004 John Wiley & Sons, Ltd. [source] | |||||||||||||