Showing papers by "American University in Cairo published in 1995"

Component redundancy vs system redundancy in the hazard rate ordering

Abstract: Design engineers are well aware of the stochastic result which says that (under the appropriate assumptions) redundancy at the component level is superior to redundancy at the system level. Given the importance of the hazard rate in reliability and life testing, we investigate to what extent this principle holds for the stronger stochastic ordering, viz, hazard rate ordering. Surprisingly, this does not hold for even series systems if the spares do not match the original components in distribution. It is true for series systems however for matching spares, and we conjecture that this is the case in general for k-out-of-n:G systems. We also investigate this principle for cold-standby redundancy (as opposed to active or parallel redundancy).

A study of workability criteria in bulk forming processes

Abstract: This study presents a critical review, and comparison of workability criteria in bulk forming processes. Various well established criteria, are classified into appropriate groups, and a simple comparison between them is performed based on theoretical basis. An elastic-plastic large strain finite element technique is also used to predict workability limits using some of these criteria, with special emphasis on upsetting operations. The workability criteria are investigated based on their ability to predict fracture initiation sites and critical level of deformation up to fracture.

The public health implications of the increasing predominance of Schistosoma mansoni in Egypt: a pilot study in the Nile delta.

Abstract: Over the past twenty years, Schistosoma mansoni has apparently replaced Schistosoma haematobium as the more prevalent species of schistosomiasis in the Nile delta. In this paper we show that this change has profound implications for public health strategies, in particular the provision and utilization of diagnostic and treatment services for the Egyptian rural population, and for health education programmes. The processes of providing and seeking treatment for the two forms of schistosomiasis are quite distinct as they have different signs and symptoms and are diagnosed in stool and urine samples respectively. In two Nile delta villages, where S. mansoni has almost completely replaced S. haematobium, we found that health services were geared primarily to S. haematobium, and hence many cases of S. mansoni remain undiagnosed and untreated. One reason for this is that health unit staff and local people lacked detailed knowledge of the two forms of schistosomiasis, indicating the need for health education.

Adjustment for stabilisation or growth? Ghana and the Gambia

Abstract: Ghana and The Gambia are part of the group of African states that have been following programmes of structural adjustment (SAPs) throughout most of the 1980s and into the 1990s. They are also amongst the states that the Bretton Woods institutions (BWIs) have periodically cited as success stories for adjustment. The aims of adjustment policies are well known to analysts of African political economy. Their theoretical foundations lie within a brand of neo‐classical economics that emphasises the advantages of nonintervention in the free market and, conversely, the risks attendant on state attempts to regulate or intervene in the market. It follows that this line of thought anathematises the attempts of various African states to promote indigenous industrial development. State spending on such aims is deemed inflationary and wasteful inasmuch as it is believed to promote inefficient industries that can only survive on the basis of state subsidisation and protection against foreign competition. State concentra...

Schistosomiasis control through rural health units.

Abstract: In Egypt the main effort in the campaign against schistosomiasis involves providing free diagnosis and treatment through primary care facilities, especially rural health units. The prospects for improving these services are considered below.

Changing environmental conditions in the Nile delta: Health and policy implications with special reference to schistosomiasis

Abstract: Throughout the twentieth century, the major rural health problems in Egypt have been water‐related; yet environmental strategies such as water and sanitation have not been linked to health planning. A complex of interrelated environmental changes which have occurred in the Nile delta over the past 30 years, including an increase in population and domestic water use, and changing irrigation regimes, has affected patterns of transmission of water‐related diseases. These changes are examined in general, as reflected in research and policy development. Current environmental health conditions are identified in two Nile delta villages in relation to the transmission of Schistosoma mansoni which is now the predominant form of schistosomiasis in the delta; problems include canal water pollution, lack of drainage facilities for sullage and sewage and the disposal of latrine effluent. We argue that integrated schistosomiasis control strategies, which include sanitation and drainage interventions and health and hygi...

Viscous normal shock solutions including chemical, thermal, and radiative nonequilibrium

Abstract: An existing axisymmetric body viscous shock layer code including thermochemical and thermodynamic nonequilibrium and nonequilibrium radiative gasdynamic coupling was adapted to simulate the one-dimensional flow within a shock tube. A suitable solution scheme for this case and additional radiation modeling were developed in order to compare the current computational results with experimental radiation measurements. Spectrally integrated intensity traces, time to peak radiation, and ionization distance data were generated for shocks in air with speeds between 9.5-12.6 km/s. Using the current model, the dual peak characteristics of Wilson's experimental results are reproduced without the introduction of contaminant radiation. Overall, good agreement is seen between the current calculations and the available experimental data, justifying the use of the current nonequilibrium models for engineering applications.

Flexible form methods for measuring rent gradients

Abstract: We develop and demonstrate an empirical methodology for measuring rent gradients in the presence of consumers that have varying tastes for distance to the city center. We derive easily calculated measures of rent gradients, own price elasticities, and income elasticities. We demonstrate the ease of calculation of these functions, even in the presence of consumers who have nonidentical preferences. We also demonstrate how to test for bias in rent gradient estimation that arises from assuming identical preference functions.

No One Likes a Vacuum: The U.S.-Iraq War and The Search for Middle East Regional Hegemony, 1948-1990:

Abstract: This essay examines the reasons behind the 1990 war between Iraq and the United States. It employs world-systems theory and a modified concept of hegemony to present this hostility as an outcome of the historical relationship between dominant core nations and those states in the periphery and semiperiphery of the Middle East. The decline of Egypt and Iran created space for Iraq to further its ambitions as a regional power, but one unconstrained by standard inter-state practices. The U.S. reacted as a global superpower, but in the process, undermined its unique hegemonic status.

Virtual adjustment: whose reality?

Abstract: (1995). Virtual adjustment: whose reality? Review of African Political Economy: Vol. 22, No. 63, pp. 3-8.

Did the Ancient Egyptians Eat Biltong

Abstract: Marcus, J., 1992b. Dynamic cycles of Mesoamerican states. National Geographic Research & Exploration 8(4), 392-411. Marcus, J., 1993. Ancient Maya political organization, in Lowland Maya Civilization in the Eighth Century AD, eds. J.A. Sabloff & j.S. Henderson. Washington (DC): Dumbarton Oaks, 111-83. Marcus, J. & W.J. Folan, 1994. Una estela mas del siglo V y nueva informacion sobre Pata de Jaguar, gobernante de Calakmul, Campeche, en el siglo VII. Gaceta Universitaria, Ano IV, No. 15-16, 21-6. Mexico: Universidad Autonoma de Campeche. May Hau, J., R. Cohouh, R. Gonzalez & W.J. Folan, 1990. El Mapa de Calakmul. Campeche, Mexico: Centro de Investigaciones Historicas y Sociales, Universidad Autonoma de Campeche. Miller, W.F., 1992. Development of an Ecological Baseline and an Archaeological Reconnaissance Model — The Peten Region, Guatemala. Final report to NASA, Science & Technology Lab, Stennis Space Center. Ruppert, K. & J.H. Denison, Jr, 1943. Archaeological Reconnaissance in Campeche, Quintana Roo, and Peten. (CIW 543.) Washington (DC): Carnegie Institution of Washington. Schele, L. & D. Freidel, 1990. A Forest of Kings. New York (NY): Morrow. Thompson, J.E.S., 1928. The causeways of the Coba District, Eastern Yucatan. Proceedings of the 23rd International Congress of Americanists, 181-4. Tobler, W. & S. Wineberg, 1971. A Cappadocian speculation. Nature 231, 39-41.

African Socio-Cultural Formations in the 21st Century

Abstract: The paper is based on the premise that there is nothing peculiar about Africa in the modern world. Its greatest handicap is that it is the weakest link in the global chain of international capitalism. Consequently, whenever there are strains in the system, they get amplified in Africa. Depending on their magnitude, these might provoke an untold series of crises on the continent e.g. a pervasive economic crisis and local wars. In this instance internal and external factors combine to produce a configuration which could be referred to as the African problem. For this reason African scholars at different points since independence have tried to put relative weights on the external and the internal moments of the phenomenon, relying on such theories as the Dependencia and Marxism. However, at times the peculiarities of the African social formations have forced them to rethink some of the conventional terms e.g. “tribalism” or ethnicity. Slowly, a position has been reached where these are thought of as metaphores which stand for things that could be understood otherwise, as the contemporary European history shows. In spite of this, the paper argues that Africans have partly created problems for themselves by not learning from their own experience but instead rely on European analogies. Most striking among these is the idea of a “nation-state” which led to the notion of “nation-building” which degenerated into a one-party or ethnic dictatorship in most cases. This illusion is being exposed by events in Africa in what appears to be process of disintegration. It is suggested in the paper that on the contrary these should be seen as processes of deconstruction and reconstruction, which eventually will lead to the abandonment of the idea of a unitary state and adoption of different forms of federalism. On the economic frout one of the biggest illusions Africans cherished was rapid capitalist growth. This was mercilessly shattered partly because they were bereft of any national bourgeoisie and mainly because governments spawned a parasitic bureaucratic elite that prospered on state revenues which they were not able to convert into productive capital. Instead, those who became wealthy went into circulation and acted as compradors in the international arena. This facilitated vertical integration and loss of value to multinationals. Investment in the productive sectors of the economy such as agriculture and industry suffered, predisposing national economies towards the present prolonged crisis. Despite this grim picture, the paper ends on an optimistic note, namely, that the present processes of disintegration arc going to be compensated for by processes of reintegration on a wider Scale as a matter of historical necessity and political expediency. It is argued that at the popular level seeds for this have already been shown in the form of democratic pluralism and at least regional pan-Africanism. The paper urges that these be taken seriously and studied carefully so as to lay the basis for future action. Resume: Le document part de l'hypothese que rien ne distingue l'Afrique dans le monde moderne. Le plus lourd handicap du continent est qu'il constitue le maillon faiblc du capitalisme mondial. Par consequent, chaque fois que le systeme est soumis a des tensions, clles sont amplifiees en Afrique. Selon leur ampleur, elles peuvent declencher une serie de crises sur le continent, allant d'une crise economique generalisee a des guerres locales. Dans ce cas, facteurs internes et externes se conjuguent pour creer une situation que l'on pourrait qualifier dc probleme africain. C'est ainsi qu'a plusicurs occasions apres les independances, plusieurs specialistes dc l'Afrique ont tente d'attribuer une certaine ponderation aux aspects externes et internes du phenomene, en invoquant des theories telles que la dependencia et le marxisme. Toutefois, les particularites des formations sociales en Afrique les ont parfois contraints a repenser certains termes classiques comme tribalisme ou ethnicite. On en est lentement venu a les prendre pour des metaphores representant des realites qui pourraient etre comprises autrement, comme le montre l'histoire de l'Europe contemporaine. Neanmoins, le document avancc que les Africains sont en partie a l'origine de leurs problemes, incapablcs qu'ils ont ete d'apprendre de leur experience au lieu de s'inspirer d'analogics europeennes. La plus notoire est l'idee d“Etatnation” qui a conduit a la notion “d‘edification nationale” qui devait degenerer en parti unique ou en dictature ethnique la plupart du temps. Cette illusion est mise a nu par les evencments que connait l'Afrique dans ce qui ressemble a un processus de desintegration. II est suggere de voir, au contraire, ces evenements comme participant d'un processus de deconstruction et de reconstruction, qui aboutira en fin de compte a l'abandon de l'idee d'un Etat unitaire et a l'adoption de differentes formes de federalisme. Au plan economique, l'une des plus grandes illusions qui avait les faveurs des Africains est celle d'une croissance capitaliste rapide. Elle s'est completement evanouic, en partie faute de bourgeoisie nationale et principalement parce que les gouvcrnements abntaient une elite de bureaucrates parasites qui ont prospere grâce aux revenus publics qu'ils n'ont pas ete en mesure de convertir en capitaux productifs. Ceux qui se sont enrichis sc sont plutot transformes en bourgeoisie compradorc sur la scene internationale. Cela a facilite l'integration verticale et la devalorisation au profit des multinationals. L'investissement dans les secteurs productifs de l'economic tcls que l'agriculturc et l'industric en a pâti, predisposant les economics nationales a la crise prolongee actuelle. En depit de ce sombre tableau, le document termine sur une note optimiste en indiquant que le processus actucl de desintegration va etre contrebalance par une reintegration a plus grande echelle par necessite historique et opportunite politique. II est avance qu'au niveau populaire, les germes sont deja en place sous forme de pluralisme democratique et de panafricanisme regional a tout le moins. Le document invite instamment a les prendre au serieux et a les etudier soigneusement afin de jeter les bases des actions futures.

Transhumance in the Middle Ages: The eastern Pyrenees

Abstract: The political and cultural rise of early modern Europe was made possible by the economic expansion of the Middle Ages This, in turn, was predicated upon increased agricultural production and the development of the textile industry In England, the Low Countries, and northern Italy the peasants participated to the extent that workers were required to process wool and weave cloth Towns grew, the population increased, and the socio‐economic structure became more sophisticated It is natural to assume, then, that peasants in all wool producing regions benefited from this new state of affairs; it is argued that transhumance brought increased wealth and important social changes to rural communities, especially in the mountains In fact, transhumance has been misunderstood: the peasants were not full participants On the contrary, in the eastern Pyrenees as elsewhere the mountain folk suffered from the introduction of large flocks on to their communal pastures

The new international order : state, society and African international relations

Abstract: In this article Dr Wm Cyrus Reed, who is Director of the Office of African Studies and Associate Professor of Political Science at the American University in Cairo, argues that international actors based in civil society play a critical, and largely unexamined, role in African international relations.

Permanent heavy waves in circular‐shaped channels

Abstract: Because of the earth's curvature, all existing channels have a curvature. E. Zeidler gave an existence and uniqueness proof for permanent heavy and capillar-heavy waves in such circular shaped channels. Based on this proof and on a general computational method for constructing the solutions numerically, the case of permanent heavy waves in circular-shaped channels is considered in this work.

A three dimensional finite element study of the flat strip rolling process.

Abstract: Publisher Summary Several analytical models were developed to study the flat strip rolling process; most of them were based on the force equilibrium or slab method, slip line field and upper bound techniques This chapter analyzes the flat strip rolling process using a three-dimensional elastic plastic, large strain finite element formulation with accurate account of contact between the roll and the strip, and roll flattening This model is based on an elastic-plastic large strain theory with full account of the contact frictional conditions, and overcomes the drawback of the rigid plastic approach The results of the 3D model are compared with those of the conventional plane strain model The stress and the strain histories obtained from the 3D model in the deformation zone are used in a workability limit analysis to check against potential edge cracks in this process It has been found that the use of a higher reduction percent, the presence of over-cambering as well as the presence of large aspect ratio all enhance the conditions leading to edge cracking

Building a graphical user interface for the expert system of fiber reinforced plastics liquid containers

Abstract: Publisher Summary This chapter illustrates the concept of the intelligent expert system interface. This is the ability of the system to expand its own knowledge, algorithm and problem handling capabilities, without asking the human users, by communicating with the surrounding computer environment and share the knowledge of the other systems. The chapter also presents the remodeling of the expert system of the design, selection of materials and manufacturing processes of the fiber reinforced plastics liquid containers to satisfy the requirements of the intelligent expert system interface. This enables the expert system to expand its problem handling capabilities and to collect the knowledge required to handle “unfamiliar” domains. The system is able to share knowledge with other systems or even send a complete problem object to be evaluated through a neighboring expert system. The remodeled system was developed under MS WINDOWS environment and benefits from most of its collaborative features and its Arabic language support. It uses SQL commands to access remote database systems and has a direct link to use the graphical facilities of AUTOCAD.

New approach for the production of duplex composite engineering components

Abstract: Publisher Summary Many engineering components are subjected to severe wear and high-contact stresses during their use in industrial applications. This chapter explores a new approach to improve the surface properties of aluminum composite duplex components of cylindrical form, as well as to maintain their original toughness. The composite layer may be located on the outer or the inner surface according to the application need. Silicon carbide particles are incorporated into the surface of aluminum alloy heated up to its “mushy” state. Pressure is applied to get a good wetting between the aluminum alloy and the silicon carbide particles. Microstructure examination of the produced duplex alloy showed the formation of a surface layer in which the SiC particles are uniformly dispersed through the aluminum, matrix. The surface composite duplex alloy presented a hardness and wear resistance higher than the as-received aluminum matrix alloy by about 1.75 and 10 times, respectively. The success of this method widens the area of applications of such aluminum composite alloys in the production of more components especially for automobile industries.