Efficient finite element analysis using graph-theoretical force method; rectangular plane stress and plane strain serendipity family elements

Formation of a suitable null basis for equilibrium matrix is the main part of finite elements analysis via force method. Foran optimal analysis, the selected null basis matrices should be sparse and banded corresponding to produce sparse, banded and well-conditioned flexibility matrices. In this paper, an efficient method is developed for the formation of null bases of finite element models (FEMs) consisting of rectangular plane stress and plane strain serendipity family elements, corresponding to highly sparse and banded flexibility matrices. This is achieved by associating special graphs with the FEM and selecting appropriate subgraphs and forming the self-equilibrating systems (SESs) on these subgraphs. The efficiency of the present method is illustrated through three examples

Heat Transfer in Complex Fluids

Amongst the most important constitutive relations in Mechanics, when characterizing the behavior of complex materials, one can identify the stress tensor T, the heat flux vector q (related to heat conduction) and the radiant heating (related to the radiation term in the energy equation). Of course, the expression 'complex materials' is not new. In fact, at least since the publication of the paper by Rivlin & Ericksen (1955), who discussed fluids of complexity (Truesdell & Noll, 1992), to the recently published books (Deshpande et al., 2010), the term complex fluids refers in general to fluid-like materials whose response, namely the stress tensor, is 'non-linear' in some fashion. This non-linearity can manifest itself in variety of forms such as memory effects, yield stress, creep or relaxation, normal-stress differences, etc. The emphasis in this chapter, while focusing on the constitutive modeling of complex fluids, is on granular materials (such as coal) and non-linear fluids (such as coal-slurries). One of the main areas of interest in energy related processes, such as power plants, atomization, alternative fuels, etc., is the use of slurries, specifically coal-water or coal-oil slurries, as the primary fuel. Some studies indicate that the viscosity of coal-water mixtures depends not only on the volume fraction of solids, and the mean size and the size distribution of the coal, but also on the shear rate, since the slurry behaves as shear-rate dependent fluid. There are also studies which indicate that preheating the fuel results in better performance, and as a result of such heating, the viscosity changes. Constitutive modeling of these non-linear fluids, commonly referred to as non-Newtonian fluids, has received much attention. Most of the naturally occurring and synthetic fluids are non-linear fluids, for example, polymer melts, suspensions, blood, coal-water slurries, drilling fluids, mud, etc. It should be noted that sometimes these fluids show Newtonian (linear) behavior for a given range of parameters or geometries; there are many empirical or semi-empirical constitutive equations suggested for these fluids. There have also been many non-linear constitutive relations which have been derived based on the techniques of continuum mechanics. The non-linearities oftentimes appear due to higher gradient terms or time derivatives. When thermal and or chemical effects are also important, the (coupled) momentum and energy equations can give rise to a variety of interesting problems, such as instability, for example the phenomenon of double-diffusive convection in a fluid layer. In Conclusion, we have studied the flow of a compressible (density gradient type) non-linear fluid down an inclined plane, subject to radiation boundary condition. The heat transfer is also considered where a source term, similar to the Arrhenius type reaction, is included. The non-dimensional forms of the equations are solved numerically and the competing effects of conduction, dissipation, heat generation and radiation are discussed. It is observed that the velocity increases rapidly in the region near the inclined surface and is slower in the region near the free surface. Since R{sub 7} is a measure of the heat generation due to chemical reaction, when the reaction is frozen (R{sub 7}=0.0) the temperature distributions would depend only on R{sub 1}, and R{sub 2}, representing the effects of the pressure force developed in the material due to the distribution, R{sub 3} and R{sub 4} viscous dissipation, R{sub 5} the normal stress coefficient, R{sub 6} the measure of the emissivity of the particles to the thermal conductivity, etc. When the flow is not frozen (RP{sub 7} > 0) the temperature inside the flow domain is much higher than those at the inclined and free surfaces. As a result, heat is transferred away from the flow toward both the inclined surface and the free surface with a rate that increases as R{sub 7} increases. For a given temperature, an increase in {zeta} implies that the activation energy is smaller and thus, the reaction rate is increased leading to an increase in the heat of the reaction. As a result the flow is chemically heated and its temperature increase. The results shown here indicate that for all values of {zeta} used the chemical effects are significant and the temperature is always higher than both the surface temperature and the free surface temperature. The heat transfer is always from the flow toward both the inclined surface and the free stream. It is also noticed that for all values of m chosen in this study, the temperature is higher than the surface and the free stream temperature. The heat transfer at the inclined surface and at the free stream increase slowly for negative values of m to about m=0.5, but it begins to significantly increase for m greater than 0.5

Foundation Construction on Random Fill

Due to the high cost premiums associated with development on virgin lands, it is not uncommon to find new structures planned for construction over filled grounds. Such structures vary in function ranging from industrial facilities to public institutions. This paper presents three case histories related to construction or shallow foundations on random fill for a factory building, a public library, and a college building. The factory building was constructed partly over deep uncontrolled fill with little foundation improvement and partly over residual soils. The library was constructed partly over a randomly filled, abandoned quarry and partly over pinnacled limestone and residual soils. Foundations in the quarry area were treated by preloading, while others were improved by selective undercutting. Foundations for the college building were constructed on improved ground using deep dynamic compaction. The case histories illustrate that shallow foundations, with some type of ground improvement, can be used in uncontrolled fill areas. In limited cases, where a greater differential movement can be tolerated, foundations may require relatively little ground improvement. In all cases, however, where shallow foundations arc planned for construction over uncontrolled fill, it is paramount to recognize and disclose the attendant risk to future settlement

Hydraulics of river bed degradation, Willow Creek, Iowa

The degradation of stream channels in western Iowa has resulted in scour and erosion problems at most of the bridge crossings of these streams. As a result, frequent maintenance, extension of spans, and reinforcement of bridge piers have been required. The cost has been a burden to the counties and the state. The critical streams are those which have been straightened in the past for flood control and land reclamation purposes. Willow Creek, the study watershed, is typical of these straightened streams;Grade stabilization structures have been designed to control the degradation at great cost. However, the optimal engineering solution to the problem depends highly on an adequate understanding of the mechanics of erosion and sediment transport, and of the upstream progression of degradation;The ultimate, future equilibrium profile is the fundamental and determinng factor when designing grade stabilization structures for controlling degradation. A channel equilibrium profile model to estimate the final equilibrium profile of Willow Creek, a stream with a drainage area of 130 square miles (337 sq. km) is presented;The computer model components are based on the hydraulic and hydrological characteristics of the stream. The deepening and the widening of the stream cross section were included in the formulation of the model, and these results and the equilibrium profile constitute the computer output;The model was applied to Willow Creek, and the final equilibrium profile of the stream was estimated for three trial dominant discharge values and for one value of the critical tractive force. The dominant discharge for Willow Creek was determined to be the magnitude of the 5-year frequency flood;The simplicity and flexibility of the methods used make them applicable to other streams in western Iowa. Data requirements for ungaged streams are drainage area and land use characteristics, stream slope, stream bed and channel characteristics and existing profile data

Achieving Competitive Advantage by Using Supply Chain Strategies

The subject of the supply chain has received significant attention by researchers in the theoretical and applied fields of Operations Management and Marketing Management. Resulting in the need to develop successful strategies of supply chain and complement the organization's strategy in order to achieve competitive advantage. From this point view, the research problem was identified by asking questions about the strategies of supply chain and its suitability to the Company studied, as well as the knowledge of the requirements for successful supply chain, also knowing the effect of these strategies in achieving competitive advantage to the plant under study. The main objective of this research is to identify the relationship between supply chain strategies and competitive advantage in Alsamah Hosiery Company, Syria. The research used the null hypothesis to determine the relation and effect between the study variables which is strategies of supply chain and the dimensions of competitive advantage. The result showed that supply chain is part of a value chain that deals with key activities in the company, also supply chain strategies has an impact on the companys competitive advantage. The external supply strategy had the highest impact. A number of recommendations have been put forward to the factory studied, most importantly, the need to build long-term relationships with suppliers and trend towards establishing a partnership as well as the need to adopt competitive standards by the factory management in the selection of suppliers (cost, quality, and fast delivery). Keywords: Supply chain, Vertical integration strategy, External supply strategy, Competitive advantage

Adopting Lean Supply Chain at Unipharma Syria to Improve its Response to Clients

Abstract This research aims to test the impact of the adoption of lean supply chain standards in improving Unipharma Syria response to its clients' posts the Syrian crisis of 2011. The researcher used descriptive and analytical approach to study Universal Pharmaceutical Industries. UNIPHARMA one of the well-known highly developed firms in the Pharmaceutical Industries in Syria. The data was collected from a questionnaire distributed to 100 employees working at Unipharma Damascus, 98 valid responses were received. The hypotheses were tested using SPSS software. The result of the research showed that the company's reliance on process standardization and industrial standards was relatively high and the adoption rate for industrial standards are the highest. The company's response rate to its customers in terms of flexibility and delivery is not high and convergent for both variables. Keywords lean supply chain, customer response, Process Standardization, Industrial Standard

Quasi-Elastic Neutrino Reactions on Carbon and Lead Nuclei

We examine neutral-current quasi-elastic neutrino-nucleus reactions on $^{12}$C and $^{208}$Pb targets. We use the relativistic mean field theory approach to describe the nuclear dynamics. We compute the cross sections for the scattering of 150-MeV, 500-MeV and 1000-MeV neutrinos on a $^{12}$C target and study the effect of the strange-quark content of the nucleon which appears in these reactions via the isoscalar weak current. We compare our results with the data of the MiniBooNE experiment for mineral oil (CH$_2$). We also calculate the cross section for the quasi-elastic neutron knockout reaction of 20 to 60-MeV neutrinos on a $^{208}$Pb target which is relevant to plans to use lead as a target material in future supernova neutrino detectors.Comment: 28 pages, 14 figure