Solid-state synthesis and characterization of LiCoO2 and LiNi y Co1−y solid solutions

Solid solutions of compositions LiNi _y Co_1−y O₂ (y = 0.0, 0.1 and 0.2) were prepared by solid-state fusion synthesis from carbonate precursors. Material characterization was carried out using XRD. Formation mechanisms of the products are discussed in the light of TG/DTA results. Nickel-containing compositions gave higher discharge capacities and smaller hystereses in their charge-discharge profiles which make them more attractive than pristine LiCoO₂ as cathode materials in high-energy lithium cells. The lower loss in capacity per cycle for cells with unsubstituted LiCoO₂, as determined from cycling studies up to 25 cycles, makes it more suitable than the substituted ones for long cycle-life cells with low capacity fade.     

Polyaniline as an electrode material for magnesium reserve battery

The results of the investigation on the use of polyaniline (PANI) as a cathode material in a battery configuration, having magnesium as anode and a neutral aqueous solution of one of the magnesium salts such as perchlorate, chloride and bromide as an electrolyte, are presented. This system shows a open circuit voltage in the range 1.6-1.8 V. The study indicates that the capacity of the system largely depends upon the anion present in the electrolyte.     

A new algorithm for encryption/decryption for field applications

This paper proposes a novel scheme where the key k is generated as discrete logarithm of indices involving prime modulus p and any base value q. This base value q is an element of Z_p. The Discrete logarithm values are substituted for k in the encryption equation. During decryption the corresponding k’s are used to recover the plaintext. The sender embeds the p, q values along with the encrypted message and transmits it. This obviates the need for sending the full-length key along with the encrypted message. The proposed method ensures higher security in the transmission. The strength of the method lies in the difficulty of guessing p, q values, the entire key need not be transmitted and the full set of ASCII values of the Z₂₅₆ plane figure in the encryption process. The paper also discusses the difficulty of attempting brute force technique to discover p, q values. As an extension of this work, the authors are exploring the possibility of using the full set of UNICODE values instead of the restricted 8-bit ASCII set.     

Electrochemical behaviour of LiM y Mn2−y O4 (M = Cu, Cr; 0 ≤y ≤ 0.4)

Spinel lithium manganese oxide, LiMn₂O₄, is beset with problems of capacity fade upon repeated cycling. The loss in capacity upon cycling is attributable to Jahn-Teller distortion and manganese dissolution in the electrolyte in the charged state. One way to circumvent this capacity fade is to introduce other 3d bdtransition metal ions in the LiMn₂O₄ lattice. In this paper, we report on the effect of partial substitution of manganese in the LiMn₂O₄ phase with copper (II) and chromium (III) ions. It has been shown that the higher octahedral stabilization energy of trivalent chromium imparts greater structural stability to chromium-doped LiMn₂O₄ spinels. Both copper and chromium reduce the capacity of the spinel in the 4 V region. In terms of its good reversible capacity and ability to sustain cycling with minimal capacity fade, LiCr_0.1Mn_1.9O₄ may be considered as a potential cathode material for lithium rechargeable cells.     

A novel membrane-inspired multiverse optimizer algorithm for quality of service-aware cloud web service composition with service level agreements

Cloud computing is an emerging technology in computing that provides different services over the Internet. It needs composite services to perform a complex task. Optimal selection of services that provides both functionality and nonfunctionality requirements is an NP-hard problem. This study uses nondeterministic parallel and distributed structures of membrane systems for the recently improved multiverse optimization algorithm to improve the quality of solutions. In the previous membrane-inspired algorithm, the population was divided into subpopulations that evolve different dynamic membranes. This study not only uses a conventional membrane-inspired approach to introduce a conventional membrane-inspired multiverse optimizer (CMIMVO) for the first time but also proposes an algorithm that divides the variables (dimension) into subgroups for different membranes called proposed membrane-inspired multiverse optimizer (PMIMVO). Thus, in PMIMVO, each membrane works on a subgroup to gain global information, which considers the best values obtained by other membranes for other variables. The PMIMVO shows promising results on benchmark function problems. Furthermore, simulation results show that the PMIMVO approach could achieve up to 38% improvement in integrated quality of service (QoS) with attributes including response time, price, availability, and reliability in comparison with the previous approaches, including genetics algorithm (GA), particle swarm optimization (PSO), gravitational search algorithm (GSA), moth–flame optimization (MFO) improved multiverse optimizer (MVO), and CMIMVO.