North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Catalysis. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

New ways of polymeric ion track characterization

Abstract: New ways have been applied for characterization of ion tracks in polymers in the last few years, which are essentially related to depth profile determinations of ions, molecules, or positrons penetrating into these tracks In combination with tomography, the first three-dimensional results have been obtained Extensive diffusion simulations accompanying the measurements have enabled us to obtain a better understanding of the transport processes going on in ion tracks This paper gives an overview about the range of new possibilities accessible by these techniques, and summarizes the presently obtained understanding of ion tracks in polymers

New D–D′–A Configured Dye for Efficient Dye-Sensitized Solar Cells¶

Abstract: D−π–A, D–A−π–A, and other configuration-based organic dyes have shown great potential in the field of dye-sensitized solar cells (DSCs) Compared with traditional configurations, D–D′–A offers several advantages such as enrichment of the electron-donating ability, absorption spectral region, and molar extinction coefficient and inhibits dye aggregation Hence, in this work, a novel D–D′–A-type dye has been designed and synthesized for DSC applications In this configuration, substituted imidazole has been used as a primary donor, phenothiazine as an auxiliary donor, and cyanoacetic acid as an acceptor/anchoring group Structural characterizations of a D–D′–A-type dye were done by using NMR and electron ionization–mass spectrometry Photophysical, electrochemical, and computational studies were systematically performed to evaluate its electronic transitions, light-harvesting property, highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) levels, and redox behavior The photop

Using game theory to model DoS attack and defence

Abstract: Denial of service (DoS) or distributed denial of service (DDoS) attacks based on bandwidth depletion remain a persistent network security threat and have always been an important issue for system administrators and researchers. Defence mechanisms proposed so far to defend against such attacks could not address the problem adequately and efficiently due to lack of quantitative approaches in modelling defence strategies against DoS/DDoS attacks. Game theory is a microeconomic and mathematical tool that provides a quantitative framework to model such attacks. A model based on game theory can act as a decision support system to the defender and augments its capabilities to take best decisions for maintaining an optimum level of network security round the clock against such attacks. Inspired by this, different DoS/DDoS scenarios, where game theory has been used to represent the strategic interaction between the attacker and a defender, are investigated. Based on the strategic interactions, a game theoretical defence mechanism is proposed to mitigate DoS/DDoS attacks. The proposed mechanism is based on two-player zero-sum game. It considers DoS/DDoS attack based on bandwidth depletion where an attacker wants to occupy maximum bandwidth of a link having a limited capacity. The attacker does so by flooding the network with unsolicited or malicious flows. The attacker has to decide an effective attack rate per flow. It has to choose an optimal size of botnet also for a cost-effective attack. It does trade-off analysis prior to attack. If its payoff or benefit obtained is less than the attack cost, it chooses to refrain from launching such a costlier DoS/DDoS attack. On the other hand, to set an upper bound on network traffic, the defender needs to set an optimum threshold per flow so that maximum attack flows are either dropped or redirected to a honeypot deployed in the network. Arbitrary setting of a threshold for flow rates can also cause a loss of legitimate flows. The defender chooses the optimum threshold value with precise estimation to minimize loss of legitimate flows. The defender also does trade-off analysis and sets the threshold in a way that can minimize the attacker’s payoff. This optimization problem is presented as a game between the attacker and defender. Action sets and objective functions of both players are defined. The network constrains are modelled and payoffs are calculated. The game converges to Nash equilibrium. The best course of actions is deduced from the Nash strategies. Results obtained by simulation and numerical calculations are in favour of the proposed game theoretical defence mechanism and strongly advocate the worthiness of using game theory to defend against DoS and DDoS attacks to strengthen network security.

Catalytic Conversion of Atmospheric CO2 into Organic Carbonates by Nickel(II) Complexes of Diazepane-Based N4 Ligands.

Abstract: Activation of CO2 and conversion into value-added products is an effective option to mitigate CO2 emission. The nickel(II) complexes [Ni(L1)](ClO4)2 1, [Ni(L2)](ClO4)2 2, and [Ni(L3)(CH3CN)2](Ph4B)...