On the Coefficients and the Growth of Gap Power Series

In this paper we are interested in the limiting case, in which not the behavior of f in an angle, but only on a radius, for example z = x > 0, is known. Fabry gaps no longer suffice to get information about the growth of m(r) = [...], since already Pólya pointed out [11, p. 636] that there exist entire functions with Fabry gaps (even [...]), which are bounded for x > 0

Prospects for using carbon-carbon composites for EMI shielding

Since pyrolyzed carbon has a higher electrical conductivity than most polymers, carbon-carbon composites would be expected to have higher electromagnetic interference (EMI) shielding ability than polymeric resin composites. A rule of mixtures model of composite conductivity was used to calculate the effect on EMI shielding of substituting a pyrolyzed carbon matrix for a polymeric matrix. It was found that the improvements were small, no more than about 2 percent for the lowest conductivity fibers (ex-rayon) and less than 0.2 percent for the highest conductivity fibers (vapor grown carbon fibers). The structure of the rule of mixtures is such that the matrix conductivity would only be important in those cases where it is much higher than the fiber conductivity, as in metal matrix composites

On the comparison of two numerical methods for conformal mapping

Let G be a simply-connected domain in the t—plane (t = x + iy), bounded by the three straight lines x = 0, y = 0, x =1 and a Jordan arc with cartesian equation y = τ (X). Also, let g be the function which maps conformally a rectangle R onto G, so that the four corners of R are mapped onto those of G. In this paper we show that the method con-sidered recently by Challis and Burley [2], for determining approx- imations to g, is equivalent to a special case of the well-known method of Garrick [8] for the mapping of doubly-connected domains, Hence, by using results already available in the literature, we provide some theoretical justification for the method of [2]

Intercalated graphite fiber composites as EMI shields in aerospace structures

The requirements for electromagnetic interference (EMI) shielding in aerospace structures are complicated over that of ground structures by their weight limitations. As a result, the best EMI shielding materials must blend low density, high strength, and high elastic modulus with high shielding ability. In addition, fabrication considerations including penetrations and joints play a major role. The EMI shielding properties are calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compared to preliminary experimental results and to shields made from aluminum. Calculations indicate that EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding properties alone

Technological hurdles to the application of intercalated graphite fibers

Before intercalated graphite fibers can be developed as an effective power material, there are several technological hurdles which must be overcome. These include the environmental stability, homogeneity and bulk properties, connection procedures, and costs. Strides were made within the last several years in stability and homogeneity of intercalated graphite fibers. Bulk properties and connection procedures are areas of active research now. Costs are still prohibitive for all but the most demanding applications. None of these problems, however, appear to be unsolvable, and their solution may result in wide spread GOC application. The development of a relatively simple technology application, such as EMI shielding, would stimulate the solution of scale-up problems. Once this technology is developed, then more demanding applications, such as power bus bars, may be possible

Method of intercalating large quantities of fibrous structures

A method of intercalating large quantities of fibrous structures uses a rotatable reaction chamber containing a liquid phase intercalate. The intercalate liquid phase is controlled by appropriately heating, cooling, or pressurizing the reaction. Rotation of the chamber containing the fiber sample enables total submergence of the fiber during intercalation. Intercalated graphite fibers having metal-like resistivities are achieved and are conceivably useful as electrical conductors

Environmental stability of intercalated graphite fibers

Graphite fibers intercalated with bromine, iodine monochloride, ferric chloride, and cupric chloride were subjected to stability tests under four environments which are encountered by engineering materials in the aerospace industry: ambient laboratory conditions, as would be experienced during handling operations and terrestrial applications; high vacuum, as would be experienced in space applications; high humidity, as would be experienced in marine applications; and high temperature, as would be experienced in some processing steps and applications. Monitoring the resistance of the fibers at ambient laboratory conditions revealed that only the ferric chloride intercalated fibers were unstable, due to absorption of water from the air. All four types of intercalated fibers were unstable, due to absorption of water from the air. All four types of intercalated fibers were stable for long periods under high vacuum. Ferric chloride, cupric chloride, and iodine monochloride intercalated fibers were sensitive to high humidity conditions. All intercalated fibers began to degrade above 250 C. The order of their thermal stability, from lowest to highest, was cupric chloride, iodine monochloride, bromine, and ferric chloride. Of the four types of intercalated fibers tested, the bromine intercalated fibers appear to have the most potential for application, based on environmental stability

Heat transfer device and method of making the same

Gas derived graphite fibers are generated by the decomposition of an organic gas. These fibers when joined with a suitable binder are used to make a high thermal conductivity composite material. The fibers may be intercalated. The intercalate can be halogen or halide salt, alkaline metal, or any other species which contributes to the electrical conductivity improvement of the graphite fiber. The heat transfer device may also be made of intercalated highly oriented pyrolytic graphite and machined, rather than made of fibers

Religious Parties in the Political Systems of Pakistan and Israel

The modern states of Pakistan and Israel share common concepts in regard of state and nation just as in regard of civic and religious identity discourses. In addition to this they show significant parallels within those historic processes which led to their creation in 1947 and 1948 and thus provide an adequate basis in terms of a cross-country comparison. In spite of the secular visions of their founding movements a fertile ground based on religion provided the cultural basis for nation- and land-oriented ideologies. The creation of a homeland for a religious community and the thus connected civic identity of its citizens as a religious and nationalist synthesis form a contrast to the common character of the international community of states and reflect the search for a national identity. In terms of an intellectual exchange, basic ideas of the Jewish enlightenment influenced the claim of Muhammad A. Jinnah's Pakistan Movement for a sovereign Muslim statehood. Since both states offer a broad ideological platform which includes both, secular as well as religious interpretations, the project focuses on religious parties which try to implement theo-political models of a religious state parallel to the contemporary discourses on nation-building existing in these two states. The complex nucleus of nation, religion and politics demands an in-depth analysis of the concepts of partition, border and ethnicity and how they contradict the state's ideological core. Based on research data conducted in field-research in Pakistan, India and Israel this paper emphasizes the transformation of traditional religion-state tensions and cleavages, illustrated by a cross-country comparison within an institutional and sociopolitical framework of analysis

Density of intercalated graphite fibers

The density of Amoco P-55, P-75, P-100, and P-120 pitch-based graphite fibers and their intercalation compounds with bromine, iodine monochloride, and copper (II) chloride have been measured using a density gradient column. The distribution of densities within a fiber type is found to be a sensitive indicator of the quality of the intercalation reaction. In all cases the density was found to increase, indicating that the mass added to the graphite is dominant over fiber expansion. Density increases are small (less than 10 percent) giving credence to a model of the intercalated graphite fibers which have regions which are intercalated and regions which are not