A new look at numerical analyses of free-edge stresses in composite laminates

The edge stress problem for a + or - 45 deg graphite/epoxy laminate was examined. The reliability of the displacement formulated finite element method in analyzing the edge stress problem was investigated. Analyses of two well known elasticity problems, one involving a stress discontinuity and one a singularity, showed that the finite element analysis yields accurate stress distributions everywhere except in two elements closest to the stress discontinuity of singularity. Stress distributions for a + or - 45 deg laminate showed the same behavior near the singularity found in the well known problems with exact solutions. The displacement formulated finite element method appears to be a highly accurate technique for calculating interlaminar stress in composite laminates. The disagreement among the numerical methods was attributed to the unsymmetric stress tensor at the singularity

Counting Giant Gravitons in AdS_3

We quantize the set of all quarter BPS brane probe solutions in global AdS_3 \times S^3 \times T^4/K3 found in arxiv:0709.1168 [hep-th]. We show that, generically, these solutions give rise to states in discrete representations of the SL(2,R) WZW model on AdS_3. Our procedure provides us with a detailed description of the low energy 1/4 and 1/2 BPS sectors of string theory on this background. The 1/4 BPS partition function jumps as we move off the point in moduli space where the bulk theta angle and NS-NS fields vanish. We show that generic 1/2 BPS states are protected because they correspond to geodesics rather than puffed up branes. By exactly quantizing the simplest of the probes above, we verify our description of 1/4 BPS states and find agreement with the known spectrum of 1/2 BPS states of the boundary theory. We also consider the contribution of these probes to the elliptic genus and discuss puzzles, and their possible resolutions, in reproducing the elliptic genus of the symmetric product.Comment: 47 pages; (v2) references and minor clarifications adde

Content-Centric Networking at Internet Scale through The Integration of Name Resolution and Routing

We introduce CCN-RAMP (Routing to Anchors Matching Prefixes), a new approach to content-centric networking. CCN-RAMP offers all the advantages of the Named Data Networking (NDN) and Content-Centric Networking (CCNx) but eliminates the need to either use Pending Interest Tables (PIT) or lookup large Forwarding Information Bases (FIB) listing name prefixes in order to forward Interests. CCN-RAMP uses small forwarding tables listing anonymous sources of Interests and the locations of name prefixes. Such tables are immune to Interest-flooding attacks and are smaller than the FIBs used to list IP address ranges in the Internet. We show that no forwarding loops can occur with CCN-RAMP, and that Interests flow over the same routes that NDN and CCNx would maintain using large FIBs. The results of simulation experiments comparing NDN with CCN-RAMP based on ndnSIM show that CCN-RAMP requires forwarding state that is orders of magnitude smaller than what NDN requires, and attains even better performance

Recruitment of the Fouling Bivalve, Mytilopsis sallei (Recluz), on Metallic and Nonmetallic Surfaces at Visakhapatnam Harbor, India

In 1967, the dreissinid bivalve, Mytilopsis saUei (Recluz), was first noticed in Indian waters at the Southern Lighter Channel of Visakhapatnam harbor, Andhra Pradesh, India. It is believed that his species was introduced into the Indo-Pacific region from Central America via the Panama Canal and Fiji through ship foulin

Flocculation of iron ores using magnafloc polymers

Flocculation of iron ore fines using two different anionic polymers based on polyacrylamide.The results obtained were presented

Zeta potential and flocculation behavior on iron ore fines using magnafloc polymers.

The flocculation behavior of iron ore fines using Magnafloc polymers as flocculants was studied along with zetapotential measurements.Correlation between zetapotential data and flocculation was examined and discussed.The mechanism of flocculant adsorption on mineral surface was suggested

Adhesion between silica surfaces due to hydrogen bonding

The adhesion between surfaces can be enhanced significantly by the presence of hydrogen bonding. Confined water at the nanoscale can display behaviour remarkably different to bulk water due to the formation of hydrogen bonds between two surfaces. In this work we investigate the role of confined water on the interaction between hydrophilic surfaces, specifically the effect of organic contaminants in the aqueous phase, by measuring the peak adhesive force and the work of adhesion. Atomic force microscope cantilevers presenting hemispherical silica tips were interacted with planar single crystals of silica in the presence of dimethylformamide, ethanol, and formamide; solution compositions in the range 0-100 mol% water were investigated for each molecule. Each molecule was chosen for its ability to hydrogen bond with water molecules, with increasing concentrations likely to disrupt the structure of surface-bound water layers. With the exception of aqueous solutions containing low concentrations of ethanol, all molecules decreased the ability of confined water to enhance the adhesion between the silica surfaces in excess of the predicted theoretical adhesion due to van der Waals forces. The conclusion was that adhesion depends strongly on the formation of a hydrogen-bonding network within the water layers confined between the silica surfaces

Making On-Demand Routing Efficient with Route-Request Aggregation

In theory, on-demand routing is very attractive for mobile ad hoc networks (MANET), because it induces signaling only for those destinations for which there is data traffic. However, in practice, the signaling overhead of existing on-demand routing protocols becomes excessive as the rate of topology changes increases due to mobility or other causes. We introduce the first on-demand routing approach that eliminates the main limitation of on-demand routing by aggregating route requests (RREQ) for the same destinations. The approach can be applied to any existing on-demand routing protocol, and we introduce the Ad-hoc Demand-Aggregated Routing with Adaptation (ADARA) as an example of how RREQ aggregation can be used. ADARA is compared to AODV and OLSR using discrete-event simulations, and the results show that aggregating RREQs can make on-demand routing more efficient than existing proactive or on-demand routing protocols