Interconnected Segments Research Articles

An electromigration model that includes the effects of microstructure and temperature on mass transport

A model for electromigration in thin metal film interconnects is presented that includes two components of diffusion. The grain-boundary and lattice components of mass transport are considered in terms of their temperature dependence and the metallurgical ‘‘structure’’ of patterned planar interconnects. Interconnect structure is defined in terms of single- and polycrystalline line segments, which result from the local grain microstructure for a patterned interconnect line. The dependence of the diffusional flux on the length and type of line segment is included in the model. The results indicate that the grain structure of the film plays an important role in determining the relative contribution of the diffusion components to mass transport. The model assumes that the length and type of interconnect line segment determines the relative contribution of grain boundary and lattice diffusion components, and provides a means for extrapolating accelerated test results for planar interconnects by taking into consideration the temperature dependence of the diffusion mechanisms, and the effect of the local microstructure on diffusion. The model also indicates that extrapolations made using Black’s equation may result in an overestimate of safe operating conditions. Calculations show that the effective activation energy depends on the median grain size and its distribution parameter, D50 and σ, respectively, and the interconnect linewidth W. Model calculations of electromigration lifetime t50 were compared to experimental results obtained on patterned interconnects using sputter-deposited Al-1.5% Cu alloy films. The experimental data support a linewidth-dependent electromigration activation energy and show that the dependence of t50 on linewidth for W≤3D50 results from a change in the dominant diffusion mechanism with temperature, linewidth, and local interconnect ‘‘structure.’’

Mathematical modelling of the human cardiovascular system in the presence of stenosis

This paper reports a theoretical study on the distribution of blood flow in the human cardiovascular system when one or more blood vessels are affected by stenosis. The analysis employs a mathematical model of the entire system based on the finite element method. The arterial-venous network is represented by a large number of inter-connected segments in the model. Values for the model parameters are based upon the published data on the physiological and rheological properties of blood. Computational results show how blood flow through various parts of the cardiovascular system are affected by stenosis in different blood vessels. No significant changes in the flow parameters of the cardiovascular system were found to occur when the reduction in the lumen diameter of the stenosed vessels was less than 65%.

Mathematical modelling of flow distribution in the human cardiovascular system.

The paper presents a detailed model of the entire human cardiovascular system which aims to study the changes in flow distribution caused by external stimuli, changes in internal parameters, or other factors. The arterial-venous network is represented by 325 interconnected elastic segments. The mathematical description of each segment is based on equations of hydrodynamics and those of stress/strain relationships in elastic materials. Appropriate input functions provide for the pumping of blood by the heart through the system. The analysis employs the finite-element technique which can accommodate any prescribed boundary conditions. Values of model parameters are from available data on physical and rheological properties of blood and blood vessels. As a representative example, simulation results on changes in flow distribution with changes in the elastic properties of blood vessels are discussed. They indicate that the errors in the calculated overall flow rates are not significant even in the extreme case of arteries and veins behaving as rigid tubes.

Performance analysis of bridged LANs

As the requirements of LANs have evolved, an increasing number of LANs now incorporate MAC bridges. In many instances, however, the choice of bridges, and the interconnection topologies used with them, is being made based on technological grounds rather than on firm predictions of improvements in overall network response times. The paper identifies the issues that must be considered when expanding a LAN and also, through a series of simulation results, illustrates the effect on the overall network performance of various bridge parameters and interconnection topologies. The paper concludes with some guidelines to be followed for creating a bridged LAN comprising many interconnected segments.

Network properties of a two-dimensional natural fracture pattern

The influence that fractures exert on the permeability of a fractured rock is, to a large extent, controlled by the nature of the network formed by the fracture system. Here, the network properties of a two-dimensional natural pattern, mapped from the surface of a sandstone layer, are investigated and compared to those of realizations of spatially randomly distributed line segments with similar orientation and length distributions and line segment density (line length per unit area) to the natural pattern. These patterns are composed of clusters of varying size and shape, made up of interconnected fracture traces or line segments. Comparing the natural pattern with the realizations, the natural pattern was found to contain roughly half the number of clusters while the mass (total line length) of the largest cluster is approximately double that of the realizations. The size of the largest cluster controls the connectivity of the patterns, as can be seen by comparing the largest cluster of the natural pattern, which connects all four sides of the region, with those of the realizations, which are unconnected or connect only two sides. Cluster scaling characteristics were found to be similar in the natural pattern and the realizations and show a crossover from a dimension of one (their topological dimension) to two (the dimension of the embedding medium) at a point that corresponds to the fracture spacing. An investigation of the self-similarity dimension, using the box-counting method, showed similar characteristics with a broad transition zone between one- and two-dimensional behaviour at smaller box sizes. The patterns are therefore found to be non-fractal. The effect of the spatial distribution shown by the natural pattern is thus to modify the manner in which fractures are distributed among clusters, increasing connectivity (and permeability in the case of open fractures), but does not affect the cluster scaling characteristics or the self-similarity dimension of the fracture patterns.

Arnold-Chiari Malformation

The clinical findings and results of surgery in 33 cases of Chiari type I and II malformations were reviewed. Twenty patients with Chiari malformations were examined by magnetic resonance imaging (MRI), which furnished valuable information concerning the pathogenesis of and surgery for these malformations. MRI provided precise delineation of 1) the extent of herniation of the cerebellar tonsils and inferior vermis; 2) the degree of compression of the upper cervical cord and medulla; 3) the extent of cervicomedullary kinking; 4) the condition of the spinal cord, particularly whether or not a syringohydromyelia was present; 5) the nature of the communication between the fourth ventricle and syringohydromyelia or subarachnoid space; 6) the association of craniocervical anomalies and other brain malformations; and 7) the overall ventricular size. MRI also revealed the position, extent, and inner architecture of the syringohydromyelia, which could be classified as one of two types: smooth and cylindrical without septa, or a fusiform, expanded cavity having transverse septae or narrow, tubular interconnecting segments. For the latter type, syringostomy appeared not to be indicated. On the basis of the surgical results and the findings obtained by MRI, surgical bony and dural decompression in the region of the foramen magnum and upper cervical canal appear to be sufficient therapy in cases of Chiari malformations without syringohydromyelia. For those accompanied by syringohydromyelia, separation and wide opening of the fourth ventricle in addition to bony and dural decompression may be desirable. This procedure establishes a free flow of cerebrospinal fluid from the fourth ventricle and basal cistern to the spinal subarachnoid space.

The Use of Surface Faults for Estimating Design Earthquakes; Implications of the 28 October 1983 Idaho Earthquake

Research Article| August 01, 1986 The Use of Surface Faults for Estimating Design Earthquakes; Implications of the 28 October 1983 Idaho Earthquake KEVIN J. FREEMAN; KEVIN J. FREEMAN Associate The Earth Technology Corporation, 200 W. Mercer St., Seattle, WA 98119 Search for other works by this author on: GSW Google Scholar STEVE FULLER; STEVE FULLER Project Geologist The Earth Technology Corporation, 200 W. Mercer St., Seattle, WA 98119 Search for other works by this author on: GSW Google Scholar BRUCE A. SCHELL BRUCE A. SCHELL Senior Geologist The Earth Technology Corporation, 3777 Long Beach Blvd., Long Beach, CA 90807 Search for other works by this author on: GSW Google Scholar Author and Article Information KEVIN J. FREEMAN Associate The Earth Technology Corporation, 200 W. Mercer St., Seattle, WA 98119 STEVE FULLER Project Geologist The Earth Technology Corporation, 200 W. Mercer St., Seattle, WA 98119 BRUCE A. SCHELL Senior Geologist The Earth Technology Corporation, 3777 Long Beach Blvd., Long Beach, CA 90807 Publisher: Association of Environmental & Engineering Geologists First Online: 02 Mar 2017 Online Issn: 1558-9161 Print Issn: 1078-7275 © 1986 Association of Engineering Geologists Environmental & Engineering Geoscience (1986) xxiii (3): 325–332. https://doi.org/10.2113/gseegeosci.xxiii.3.325 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation KEVIN J. FREEMAN, STEVE FULLER, BRUCE A. SCHELL; The Use of Surface Faults for Estimating Design Earthquakes; Implications of the 28 October 1983 Idaho Earthquake. Environmental & Engineering Geoscience 1986;; xxiii (3): 325–332. doi: https://doi.org/10.2113/gseegeosci.xxiii.3.325 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract Comparison of surface ruptures of the 28 October 1983 Idaho earthquake to other historic surface ruptures such as the 1915 Pleasant Valley and 1954 Fairview Peak, Nevada earthquakes shows that maximum earthquake estimates for seismic design based on surface rupture can be misleading. Surface ruptures associated with these earthquakes are in a variety of geologic media ranging from valley alluvium to colluvium to bedrock, and occur at various positions relative to mountain fronts, all along the same rupture segments. Ruptures occurred both as continuous, interconnected segments and as discrete separated segments. Such characteristics indicate several pitfalls in the use of empirical fault-length data to estimate earthquake magnitudes for seismic-design purposes. The common practice of using well-defined surface fault segments instead of the entire length of the fault zone or fault system for estimating maximum earthquakes can lead to underestimating earthquake potential. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Morphometric study of the development of Purkinje cell dendritic trees in the mouse using vertex analysis.

Vertices are the points in an arborescence which interconnect segments and comprise terminal or pendant vertices (Vp), nodal or branching points and the root point. Branching points may be dichotomous (Vd) or trichomtomous (Vt), etc., and are subdivided into distinct two-dimensional topological entities according to the number of terminal vertices they drain, i.e. Vds comprise primary vertices (Va), connecting two Vps; secondary vertices (Vb), connecting one Vp and one Vd or one Vt; and tertiary vertices (Vc), connecting either two Vds, two Vts or one Vt and one Vd. The four types of Vt (Va', Vb', Vc', Vd') similarly connect three, two, one and zero Vps respectively. Each Vt may be transformed into two Vds thus, Va' = Va + Vb; Vb' = Va/3 + 4Vb/3 + Vc/3; Vc' = Vb + Vc and Vd' = 2Vc. Analysis proceeds by transforming mixed trees containing varying proportions of Vds and Vts into entirely dichotomous branching structures. The topology is then defined by the Va/Vb ratio which has a unique value according to the mode of growth and the frequency of Vts. Vertices are ordered by a centrifugal technique. The frequency distribution of vertices of different order allow the changes in growth characteristics and in remodelling to be detected within particular regions of the tree. Metrical parameters are readily incorporated into the analysis since all vertices are interconnected by segments of finite length and are given the same order magnitude as the vertex they drain. The analytical capabilities of the method are exemplified by its application to the study of growth and plasticity in the dendritic trees of Purkinje cells in the mouse. Growth is defined in metrical and topological terms and sites of reorganization within the mature tree are identified.

Computer Simulation for Determining Step and Touch Potentials Resulting from Faults or Open Neutrals in Urd Cable

A computer simulation is described which enables the determination of voltages on the surface and within the earth caused by: (1) a phase-to- neutral fault, (2) a fault with simultaneous open neutrals on either side, and (3) an open neutral. The buried cable and associated ground rods are modeled as a set of interconnected cylindrical segments situated in a three-dimensional, two-layered earth model. Simultaneous solution of the interconnected segment circuit and electromagnetostatic equations yields the desired solution. Output from the computer simulation is shown to match closely the data from field tests of faulted cables and other results from the literature. Work supported by EPRI contract RP797-1.

The Punctual and Segmentative Aspects of Verbs in Hopi

Verbs in the Hopi language are noteworthy for their very rich and expressive development of verbal aspects and voices. I shall say nothing in this paper of the nine voices (intransitive, transitive, reflexive, passive, semi-passive, resultative, extended passive, possessive, and cessative); and of the nine aspects (punctual, durative, segmentative, punctual-segmentative, inceptive, progressional, spatial, projective, and continuative) I shall deal with only two. It may be noted that there are no perfective and imperfective aspects; in fact Hopi does not in any way formalize as such the contrast between completion and incompletion of action. Its aspects formalize different varieties of the contrast between point-locus and extent-locus of phenomena, indifferently in time or space, or in both. Hopi also has three tenses: factual or present-past, future, and generalized or usitative. Hopi verbs belong to seven classes or conjugations having slightly different inflectional systems. Class 1, the largest and most creative class, contains a few categories not found in the other classes, among them the segmentative aspect. The simplex of the Class 1 verb is a bare root of the form CVCV, and is in the third person singular intransitive voice, punctual aspect, and present-past tense. The segmentative aspect is formed by final reduplication of this root plus the durative suffix -ta, and produces a change in the meaning of the simplex of the folloxving character: the phenomenon denoted by the root, shown in the punctual aspect as manifested about a point, becomes manifested as a series of repeated interconnected segments of one large phenomenon of a stretched-out segmental character, its extension usually being predominantly in one dimension, indifferently of space or time or both. The nature of the change can best be shown by examples. ha'ri it is bent in a rounded angle hari'rita it lies in a meandering line, making successive rounded angles (applied for instance to meander patterns in decoration)