Controlling IP Spoofing through Interdomain Packet Filters

The distributed denial-of-service (DDoS) attack is a serious threat to the legitimate use of the Internet. Prevention mechanisms are thwarted by the ability of attackers to forge or spoof the source addresses in IP packets. By employing IP spoofing, attackers can evade detection and put a substantial burden on the destination network for policing attack packets. In this paper, we propose an interdomain packet filter (IDPF) architecture that can mitigate the level of IP spoofing on the Internet. A key feature of our scheme is that it does not require global routing information. IDPFs are constructed from the information implicit in border gateway protocol (BGP) route updates and are deployed in network border routers. We establish the conditions under which the IDPF framework correctly works in that it does not discard packets with valid source addresses. Based on extensive simulation studies, we show that, even with partial deployment on the Internet, IDPFs can proactively limit the spoofing capability of attackers. In addition, they can help localize the origin of an attack packet to a small number of candidate networks.     

Dynamic optical trap generation using FLC SLMs for the manipulation of cold atoms

Abstract

Trapping and manipulation of cold atoms using optical potentials require the ability to generate and control a time varying light intensity distribution. Such an application demands that fast changing intensity distributions are generated, which are however free from flickering, or noise in general. Ferroelectric spatial light modulators are good candidates to achieve this because of their high refresh rate but they suffer from noise due to changes in the state of individual pixels during an animated sequence. A direct binary search based optimization routine was developed which minimizes the noise during such sequences. Filter sequences designed using this technique have been tested experimentally and the results demonstrated that flicker noise was eliminated.     

Isolation, enumeration and PCR characterization of aflatoxigenic fungi from food and feed samples in India

A total of 54 market samples comprising nine different food and feed commodities from Mysore city were examined in order to isolate aflatoxin-producing fungi as well as to assess aflatoxins in the commodities. Thirty-two samples were contaminated with aflatoxigenic fungi and the total mycoflora and aflatoxigenic fungi in different food and feed commodities were in the range of 0.2–260 and 0–100 cfu×10³/g, respectively. In total, 136 fungi were isolated, of which 32 were Aspergillus flavus strains and 26 of them were found to produce aflatoxins. A. flavus group of fungi comprising A. flavus, A. parasiticus, A. oryzae, A. sojae were characterized by using Aspergillus differential medium and PCR. The PCR was performed using two different sets of primers specifically targeted to aflR and omt genes of aflatoxin biosynthesis pathway. Most of the fungi belonging to A. flavus group reacted positively with the primers resulting in expected size amplicons of 796 bp for aflR and 404 bp for omt. Among the nine commodities screened for aflatoxin only, groundnut and groundnut cake were contaminated with aflatoxins B₁ and B₂. The aflatoxin contamination in these commodities exceeded the Indian regulatory limit of 30 μg/kg.     

Evaluation of Bilayer Tablet Machines—A Case Study

Four bilayer tablet compression machines were evaluated for their suitability for compression of a specific bilayer tablet formulation. Tablet machines evaluated were: Manesty (Model No. BB4), Manesty (Model No. Rotappress), Fette (Model No. P3102) and Kilian (Model No. 51AST-ZS) tablet presses. The tablet delamination tendency was the primary acceptance criteria for the evaluation of tablet press performance. The compression force on layer I was found to be the major factor influencing tablet delamination. It was found that the Kilian press was best suited for the compression of the model bilayer tablet formulation. The Kilian press is equipped with a special sampling device for layer I which allows additional compression force to be applied on layer I only at the time of weight sampling. The sampling device then returns to the original set points after sampling is completed. This feature maintains the compression force on layer I to a minimum during routine compression. Data indicated that the compression force on layer I and the compression zone in the die cavity of layer II were two factors needing to be controlled in order to yield bilayer tablets with acceptable physical characteristics.     

On the existence of solutions to linear active networks: A state-space approach

In recent literature, several alternative conditions for the existence of solutions to active networks are given. In this paper, yet another condition is given which is both necessary and sufficient for the existence of a unique solution to the network. Based on this new condition a precise upper bound for the order of complexity of an active network is established which differs from published results. A Fortran coded program is also available.     

Models of large-scale industrial energy systems—I. Simulation

The energy systems in modern industrial plants are complex and of large scale. Engineers are increasingly turning to computer models for assistance in solving the sophisticated technical problems associated with these systems. The models developed to date have covered single energy sub-systems, such as the steam or electricity system. There is a need for plant-level overview models which can assist in the co-ordination of the energy sub-systems. An overview-level simulation model is presented in this paper.Systems theory and exergy are used extensively in this research. Exergy is used in the creation of a set of variables which can represent all energy forms, allowing combination of the sub-systems into a single unified model. Systems theory is used in the development of component models and formulations.The advantages of the new model include the ability to integrate the energy sub-systems into a single model, access to well-developed techniques for handling large and complex systems, a simultaneous rather than iterative solution, and ease of computerization.     

Thermodynamic systems analysis—I. A graph-theoretic approach

An analysis of thermodynamic systems using the porcess graph model is presented in this paper. The process graph model is a linear-graph representation of systems undergoing thermodynamic processes. It provides a concise model of the interconnections and interaction interfaces of a thermodynamic system with respect to all types of flows. The analysis procedure accounts for all types of work, heat flow, and their interactions in a unified manner. The modelling and analysis procedures are illustrated by examples.The relation between the postulates of system theory and the laws of thermodynamics are stated as theorems. The first and second law analyses in thermodynamics are shown to be direct applications of network postulates from system theory. Appropriate system variables, namely, energy flow and exergy factors are introduced, which are shown to correspond to through and across variables, respectively.     

Well-Balanced Nodal Discontinuous Galerkin Method for Euler Equations with Gravity

We present a well-balanced nodal discontinuous Galerkin (DG) scheme for compressible Euler equations with gravity. The DG scheme makes use of discontinuous Lagrange basis functions supported at Gauss–Lobatto–Legendre (GLL) nodes together with GLL quadrature using the same nodes. The well-balanced property is achieved by a specific form of source term discretization that depends on the nature of the hydrostatic solution, together with the GLL nodes for quadrature of the source term. The scheme is able to preserve isothermal and polytropic stationary solutions upto machine precision on any mesh composed of quadrilateral cells and for any gravitational potential. It is applied on several examples to demonstrate its well-balanced property and the improved resolution of small perturbations around the stationary solution.     

PERFORMANCE OF AN ANNULAR CATALYTIC THREE-PHASE REACTOR FOR A SECOND ORDER REACTION

A novel annular catalytic three-phase reactor is theoretically investigated for a second order hydrogenation reaction. The results indicate that the ratio of the gaseous reactant to the liquid reactant within the reaction zone of the annular reactor can be adjusted by changing the reactor dimensions and the concentration of the gaseous reactant in the feed. As a consequence, the annular reactor may have a significant advantage over the trickle-bed reactor with respect to the selectivities that may be achieved in the reactor.     

Microprocessor in controlled transdermal drug delivery of anti-cancer drugs

Microprocessor controlled transdermal delivery of anticancer drugs 5-Fluorouracil (5-FU) and 6-Mercaptopurine (6-MP) was developed and in vitro evaluation was done. Drugs were loaded based on the pharmacokinetics parameters. In vitro diffusion studies were carried at different current density (0.0, 0.1, 0.22, 0.50 mA/cm²). The patches were evaluated for the drug content, thickness, weight, folding endurance, flatness, thumb tack test and adhesive properties all were well with in the specification of transdermal patches with elegant and transparent in appearance. In vitro permeation studies through human cadaver skin showed, passive delivery (0.0 mA/cm²) of 6-MP was low. As the current density was progressively increased, the flux also increased. the flux also increased with 0.1 mA/cm² for 15–20 min, but it was less than desired flux, 0.2 mA/cm² for 30 min showed better flux than 0.1 mA/cm² current, but lag time was more than 4 h, 0.5 mA/cm² current for more than 1 h, flux was >159 µg/cm² h which was desired flux for 6-MP. 5-FU flux reached the minimum effective concentration (MEC) of 54 μg/cm² h with 0.5 mA/cm² current for 30–45 min, drug concentration were within the therapeutic window in post-current phase. We concluded from Ohm’s Law that as the resistance decreases, current increases. Skin resistance decrease with increase in time and current, increase in the drug permeation. Interestingly, for all investigated current densities, as soon as the current was switched off, 5-FU and 6-MP flux decreased fairly, but the controlled drug delivery can be achieved by switching the current for required period of time.