Computation of Madelung Energies for Ionic Crystals of Variable Stoichiometries and Mixed Valencies and their application in Lithium-ion battery voltage modelling

Electrostatic energy (Madelung energy) is a major constituent of the cohesive energy of ionic crystals. Several physicochemical properties of these materials depend on the response of their electrostatic energy to a variety of applied thermal, electrical and mechanical stresses. In the present study, a method has been developed based on Ewalds technique, to compute the electrostatic energy arising from ion-ion interactions in ionic crystals like LixMn2O4 with variable stoichiometries and mixed valencies. An interesting application of this method in computing the voltages of lithium ion batteries employing spinel cathodes is presented for the first time. The advantages of the present method of computation over existing methods are also discussed.Comment: 15 page

Glimmers: Resolving the Privacy/Trust Quagmire

Many successful services rely on trustworthy contributions from users. To establish that trust, such services often require access to privacy-sensitive information from users, thus creating a conflict between privacy and trust. Although it is likely impractical to expect both absolute privacy and trustworthiness at the same time, we argue that the current state of things, where individual privacy is usually sacrificed at the altar of trustworthy services, can be improved with a pragmatic $Glimmer$ $of$ $Trust$, which allows services to validate user contributions in a trustworthy way without forfeiting user privacy. We describe how trustworthy hardware such as Intel's SGX can be used client-side -- in contrast to much recent work exploring SGX in cloud services -- to realize the Glimmer architecture, and demonstrate how this realization is able to resolve the tension between privacy and trust in a variety of cases

Spot propagation characteristics in laterally strained boundary layers

Owing to the importance of the spot propagation characteristics in transition zone modeling, the effect of lateral streamline convergence alone on the spot propagation characteristics has been studied. It is found that for the extent of lateral straining introduced here, the two-dimensional spot propagation characteristics are unaffected

SCC characterization of AL-Li-Cu-x Alloys

In the past several decades many Al-Li-X alloys have been studied to understand the fracture properties due to its superior specific strength and modulus over the currently dominated 2024 & 7075 type aircraft structural alloys. It is also observed that their stress corrosion resistance is also good in the peak aged condition depending on the (Li/Cu) ratio. To understand its behavior with respect to its heat treatment, a systematic collection of data is required from the published literature. We have collected such systematic data for three alloys from the early 1980’s on Al-3Li, Al-2Li-3Cu and Al-1.5Li-4.5Cu, all with 0.12Zr to keep the grain structure predominantly un-recrystalized. Such alloys were tested in the S-T direction in 3.5%NaCl solution to obtain the plateau velocities (da/dt) and threshold KIscc. It is observed that in all the alloys, (da/dt) decreased with aging heat treatment time, the decrease increased with (Li/Cu) ratio. This decrease is interpreted in terms of the degree of anodic dissolution of the grain boundary precipitates. The results are compared with theSCCbehavior of 7050 and 2024 alloys. Additional data where reversion aging treatment was given shows that grain boundary precipitates play an important role in theSCCbehavior. The overall trend in theSCCbehavior is discussed in light of the current understanding of the aluminum alloy behavior in terms of anodic dissolution and the role of hydrogen

Effect of sensitization on the stress corrosion cracking of AA5083

Stress corrosion cracking of AA5083 was evaluated using both slow strain rate testing, there was a strong effect of sensitization with aging time. Increasing aging time leads to a sharp decrease in strain to failure, as well as ultimate tensile strength (UTS). In the fully sensitized condition (175°C/240h) there was a significant effect of chloride concentration, with increasing chloride concentration leading to a sharp decrease in strain to failure and UTS. However, in the as received condition there was no significant effect of chloride concentration on the slow strain rate behavior. The difference in behavior is likely associated with continuous precipitation of β phase along the boundaries. Rising displacement tests were performed as a function of sensitization time and the Kth measured decreased sharply with aging time reaching ~4MPaÖm at 240h. The effect of chloride concentration and applied potential in the sensitized condition (175C/240h) was evaluated and the Kth decreased with increasing chloride concentration. At applied potentials below the breakdown potential of β there was an increase in the Kth but the values of Kth were not as those observed in the as received condition. The observations made suggest that the stress corrosion cracking of AA5083 was sensitive to the applied potential and chloride concentration which in turn control the crack tip conditions. The observed data were analyzed in terms of a crack tip strain rate model to quantify the behavior of AA5083

Coherent Receiver for Turbo Coded Single-User Massive MIMO-OFDM with Retransmissions

Single-user massive multiple-input multiple-output (MIMO) systems have a large number of antennas at the transmitter and receiver. This results in a large overall throughput (bit-rate), of the order of tens of gigabits per second, which is the main objective of the recent fifth-generation (5G) wireless standard. It is feasible to have a large number of antennas in mm-wave frequencies, due to the small size of the antennas. This chapter deals with the coherent detection of orthogonal frequency division multiplexed (OFDM) signals transmitted through frequency-selective Rayleigh fading MIMO wireless channels. Low complexity, discrete-time algorithms are developed for channel estimation, carrier and timing synchronization, and finally turbo decoding of the data at the receiver. Computer simulation results are presented to validate the theory

Molecular modeling of 3,4-pyridinedicarbonitrile dye sensitizer for solar cells using quantum chemical calculations

AbstractThe geometries, electronic structures, polarizabilities, and hyperpolarizabilities of organic dye sensitizer 3,4-pyridinedicarbonitrile was studied based on Hartree–Fock (HF) and density functional theory (DFT) using the hybrid functional B3LYP. Ultraviolet–visible (UV–Vis) spectrum was investigated by time dependent DFT (TD-DFT). Features of the electronic absorption spectrum in the visible and near-UV regions were assigned based on TD-DFT calculations. The absorption bands are assigned to π→π∗ transitions. Calculated results suggest that the three lowest energy excited states are due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode and 3,4-pyridinedicarbonitrile is due to electron injection process from excited dye to the semiconductor’s conduction band. The role of cyanine in 3,4-pyridinedicarbonitrile in geometries, electronic structures, and spectral properties were analyzed

Concurrency and Communication: Lessons from the SHIM Project

Describing parallel hardware and software is difficult, especially in an embedded setting. Five years ago, we started the shim project to address this challenge by developing a programming language for hardware/software systems. The resulting language describes asynchronously running processes that has the useful property of scheduling-independence: the i/o of a shim program is not affected by any scheduling choices. This paper presents a history of the shim project with a focus on the key things we have learned along the way

Evaluation of suitable sites for mud crab farming in Ratnagiri District of Maharashtra, India

The State of Maharashtra has vast stretches of estuaries, creeks and mangrove swamps, which offers great potential for aquaculture, particularly for mud crab farming. In view of the natural resources and market potential for mud crab, the Department of Forests, Government of Maharashtra plans to promote mud crab farming through a novel approach, which aims at providing livelihood support to the local communities utilizing the mangrove wetlands; thereby the local communities also shoulder the responsibility of conservation of mangroves. In this backdrop, a study was conducted to identify the suitable sites for sustainable mud crab culture, in GIS environment, based on various physical and environmental criteria including topography, soil types, landuse systems, vegetation, water quality, water availability, salinity, risks of flooding, infrastructure, seed resources and availability, market and support services. The brackishwater stretches of Anjarle, Kelshi, Aade, Velas and Ansure in the Ratnagiri district of Maharashtra were studied, and all study stations had patchy to thick mangrove vegetation. The major mangrove species encountered were: Avicennia marina, Avicennia officinalis, Sonneratia caseolaris, Rhizophora mucronata and Acanthus ilicifolius. The pH of water was near-neutral to alkaline, whereas dissolved oxygen levels were found to be within the ideal range. The salinity of the tidal creeks ranged from 7.24 ppt (Velas) to 35.9 ppt (Ansure) which generally varies with the tide. The ammonia levels which ranged from 0 (Aade and Ansure) to 0.5 ppm (Kelshi), falls within the safe levels for Available online at: www.mbai.org.in doi: 10.6024/jmbai.2017.59.2.2014-05 aquaculture. The sediment pH ranged from 6.2 to 8.32. The organic carbon levels in sediment ranged from 0.27 to 2.94% indicating medium to high productive nature of sediment. Samples of mud crab collected from the study areas were processed for screening for WSSV infection. All samples gave Negative results in primary as well as nested PCRs, indicating the absence of WSSV in the wild mud crab population. Integrating the analysis result along with supporting spatial data with the aid of GIS and Remote Sensing techniques, a total of 10.063 ha have been evaluated as suitable areas for mud crab farming along the brackishwater stretches of Anjarle (1.91 ha), Aade (2.069 ha), Kelshi (1.77 ha), Velas (0.538 ha) and Ansure (3.776 ha)