Privacy Preservation in Cloud Computing Using Randomized Encoding

In this era of Internet, the exchange of data between the users and service providers has grown tremendously. Organizations in health, banking, social network, criminal and government sectors have been collecting and processing the individuals’ information for their gainful purpose. However, collecting and sharing of the individuals’ information which could be sensitive and confidential, for data mining may cause a breach in data privacy. In many applications, selective data collection of confidential and sensitive information of the users’ needs to be modified for preserving it from unauthorized access and disclosure. Many data mining techniques that include statistical, k-anonymity, cryptographic, perturbation and randomization methods, etc. have been evolved for protecting and preserving data privacy. These techniques have their own limitations, it may be the case that the privacy protection is adequate or computations complexities are high and expensive. To address the limitations of the above-mentioned techniques, a methodology comprising of encoding and randomization, is proposed to preserve privacy. This technique called as Randomized Encoding (RE) technique, in which encoding is performed with addition of random noise from a known distribution to the original data for perturbing the data before its release to the public domain. The core component of this technique is a novel primitive of using Randomized Encoding (RE) which is quite similar to the spirit of other cryptographic algorithms. The reconstruction of an approximation to the original data distribution is done from the perturbed data and used for data mining purposes. There is always a trade-off between information loss and privacy preservation. To achieve balance between privacy and data utility, the dataset attributes are first classified into sensitive and quasi-identifiers. The pre-classified confidential and sensitive data attributes are perturbed using Base 64 encoding with addition of a randomly generated noise for preserving privacy. In this variable dynamic proposed approach, the result analysis of the experiment conducted suggests that the proposed technique performs computationally efficient and preserves privacy while adequately maintaining data utility in comparison with other privacy preserving techniques such as anonymization approach.

     

Design and Analysis of Multiband Fractal Antenna for MIMO/Diversity Applications

In this article a modified hybridized fractal geometry i.e., fractal antenna is proposed for Multiple Input Multiple Output (MIMO) applications. These geometries are based on Minkowski curves and Koch curves located around the boundaries of the microstrip patch of rectangular-shaped patch. The hybridized model for fractal geometry is designed and analyzed on an FR4 substrate having a thickness of 1.47 mm for the Industrial, Scientific, and Medical (ISM) frequency band. But due to the proposed fractal geometry, it resonates at three bands (2.45 GHz, 3.67 GHz, and 5.88 GHz) and it is covering the ISM band from 2.42 GHz to 2.48 GHz with a VSWR value is 1.48. Further, a 2?×?2 antenna for MIMO application is proposed by considering identical antenna elements placed in parallel on the same substrate. MIMO antenna resonates at three frequencies as same as single antenna elements and covering the same operating bands. The two elements of MIMO confguration are simulated for various sets of distance values, and optimized distance is obtained 18 mm at which a proposed antenna provides low mutual coupling value, low Envelope Correlation Coefficient (ECC), and high diversity and peak gain. The calculated values of ECC and diversity gain are 0.0002 and 10 dB, respectively which satisfy the criteria of MIMO application. The design has been experimentally validated and an appropriate similarity of experimental and simulated results is achieved.

     

Effect of dilute concentrations of Sm on the temperature‐dependent electrical and dielectric properties of ZnO

Compounds of undoped and samarium (Sm) doped ZnO have been prepared by standard solid‐state reaction method. X‐ray diffraction (XRD), Williamson‐Hall (W‐H) analysis, Transmission Electron Microscopy (TEM), temperature‐dependent electrical and dielectric studies have been done to characterize these materials. Inclusion of Sm as dopant in hexagonal wurtzite ZnO changes the lattice parameters to a small extent with some Sm aggregation at higher concentration. Also, the mean particle sizes of ZnO:Sm compounds showed an inter‐correlation with the Scherrer method, W‐H analysis as well as with TEM results. The electrical resistivity depicts an exponential decay and metal‐semiconductor transition (MST) at ~300 K for the pristine sample whereas there is large decrement in the resistivity with Sm doping. The analysis of σ_ac of ZnO suggests that the power law is obeyed and indicated an increase in the ac conductivity with Sm content. The mechanism behind this type of conductivity is elucidated by small polaron tunneling (SPT) model of conductivity. The dependence of ln dc on the temperature inverse shows that the traps of electrons are thermally activated such that low and high temperature activation energies confirm the presence of vacancies and interstitials of both O and Zn ions. Thus, a high value of dielectric constant makes these materials suitable for high frequency and charge storage device applications.     

A preliminary study of the corrosiveness of methyl fuel/gasoline blends on materials used in automotive fuel systems

A preliminary study was made of the corrosiveness of 15% by volume methyl fuel/gasoline blends on materials conventionally used for gasoline service in automotive fuel systems. The presence of water, salt and air dramatically increased the corrosiveness of the fuel. Of the metals studied, aluminum was relatively unaffected, while copper, brass, steel (types 1181 and 1008), zinc and template all showed signs of corrosion. Non-metallic samples, particularly expanded polyurethane and Buna-N. underwent greater attack in the presence of methyl fuel. Conductivity measurements showed that the presence of water and salt in the fuel can cause galvanic corrosion to occur.     

Biomolecule-entrapped SiO2 nanoparticles for ultrafast green synthesis of silver nanoparticle–decorated hybrid nanostructures as effective catalysts

Noble-metal hybrid nanostructures have gained tremendous attention due to their potential roles in biomedical and catalytic applications. In this study, for the synthesis of silver nanoparticles (Ag NPs)–silica (SiO₂) NPs, a novel green chemistry approach was employed, in which green tea biomolecule–encapsulated SiO₂ nanostructures were used for the reduction of silver ions to produce hybrid nanostructures within 300?s. The high-resolution transmission electron microscopy (HrTEM) revealed the formation of uniform ultrafine spherical Ag NPs that were evenly distributed in the nanostructures. The formed nanohybrid structures showed efficient catalytic activity for the formation of derivatives of dihydroquinoline, and retained 91% of their reusability capacity, even after 5 repeated cycles. Hence, this work provides a novel synthesis method not only for the synthesis of biomolecule-entrapped SiO₂ nanostructures, but also for the rapid formation of catalytically active hybrid nanostructures.     

Detection of latent fingerprints using luminescent Gd0.95Eu0.05PO4 nanorods

Lanthanide ions doped luminescent materials are widely studied for latent fingerprint detection. However, most of these materials are synthesized at very high temperatures and use UV C light for visualization, which is harmful to eye, skin, etc. Herein, the Gd_0.95Eu_0.05PO₄ nanorods synthesized by a simple co-precipitation method at 185 °C were reported for latent fingerprint visualization under 395 nm light. The Gd_0.95Eu_0.05PO₄ nanomaterial has monoclinic crystal structure and shows rod-shaped morphology. Further, these Gd_0.95Eu_0.05PO₄ nanorods exhibit excellent photoluminescence properties and strong fuchsia emission under UV light. These nanorods have been employed for developing latent fingerprints on various porous and non-porous substrates by the powder dusting technique, which exhibits clear and well defined details with high contrast, selectivity and sensitivity under 395 nm UV light. Latent fingerprints developed after 72 h of their deposition also show clear contrast with these nanorods. Therefore, the Gd_0.95Eu_0.05PO₄ nanorods can be used for latent fingerprint visualization applications.     

Enhancement in hydrogen production by co-cultures of Bacillus and Enterobacter

Defined co-cultures of hydrogen (H₂) producers belonging to Citrobacter, Enterobacter, Klebsiella and Bacillus were used for enhancing the efficiency of biological H₂ production. Out of 11 co-cultures consisting of 2–4 strains, two co-cultures composed of Bacillus cereus EGU43, Enterobacter cloacae HPC123, and Klebsiella sp. HPC793 resulted in H₂ yield up to 3.0 mol mol⁻¹ of glucose. Up-scaling of the reactor by 16-fold resulted in a corresponding increase in H₂ production with an actual evolution of 7.44 L of H₂. It constituted 58.2% of the total biogas. Continuous culture evolution of H₂ by co-cultures (B. cereus EGU43 and E. cloacae HPC123) immobilized on ligno-cellulosic materials resulted in 6.4-fold improvement in H₂ yield compared to free floating bacteria. This synergistic influence of B. cereus and E. cloacae can offer a better strategy for H₂ production than undefined or mixed cultures.     

Effect of medium heterogeneities on reactive dissolution of carbonates

The influence of medium heterogeneities on wormhole formation in carbonates is studied using a two-scale continuum model. The model describes the coupling between the transport and reaction processes occurring at the pore and Darcy scales. The medium heterogeneity is represented through initial porosity (or permeability) field by introducing a randomly generated normal distribution of local porosity values. Heterogeneity in the rock is characterized by the magnitude of maximum variation in local porosity value from the average porosity and by the length scale over which this variation occurs. It is found that heterogeneity in a rock affects not only the structure of the patterns formed during reactive dissolution but also the amount of acid required to achieve a given increase in permeability. The volume of acid required decreases as the heterogeneity magnitude or length scale are increased and this is particularly noticeable at high injection rates of acid. At intermediate injection rates, the required acid volume decreases gradually and an optimum value in heterogeneity magnitude may exist. This has been attributed to excessive branching in a pattern when the medium becomes extremely heterogeneous. In addition, the amount of acid required to breakthrough is found to depend on the initial rock porosity and dimensions of the rock being acidized. Finally, a novel way to characterize heterogeneity is defined, where heterogeneity at the core-scale is expressed using a heterogeneity parameter, ? as a product of the heterogeneity magnitude and length scale, and is validated for a given rock type at different injection conditions.     

Re Doping in 2D Transition Metal Dichalcogenides as a New Route to Tailor Structural Phases and Induced Magnetism

Alloying in 2D results in the development of new, diverse, and versatile systems with prospects in bandgap engineering, catalysis, and energy storage. Tailoring structural phase transitions using alloying is a novel idea with implications in designing all 2D device architecture as the structural phases in 2D materials such as transition metal dichalcogenides are correlated with electronic phases. Here, this study develops a new growth strategy employing chemical vapor deposition to grow monolayer 2D alloys of Re‐doped MoSe₂ with show composition tunable structural phase variations. The compositions where the phase transition is observed agree well with the theoretical predictions for these 2D systems. It is also shown that in addition to the predicted new electronic phases, these systems also provide opportunities to study novel phenomena such as magnetism which broadens the range of their applications.