Trust Model for Optimized Cloud Services

Cloud computing with its inherent advantages draws attention for business critical applications, but concurrently expects high level of trust in cloud service providers. Reputation-based trust is emerging as a good choice to model trust of cloud service providers based on available evidence. Many existing reputation based systems either ignore or give less importance to uncertainty linked with the evidence. In this paper, we propose an uncertainty model and define our approach to compute opinion for cloud service providers. Using subjective logic operators along with the computed opinion values, we propose mechanisms to calculate the reputation of cloud service providers. We evaluate and compare our proposed model with existing reputation models

Large Magnetoresistance and Jahn Teller effect in Sr2_2FeCoO6_6

Neutron diffraction measurement on the spin glass double perovskite Sr$_2$FeCoO$_6$ reveals site disorder as well as Co$^{3+}$ intermediate spin state. In addition, multiple valence states of Fe and Co are confirmed through M\"{o}ssbauer and X-ray photoelectron spectroscopy. The structural disorder and multiple valence lead to competing ferromagnetic and antiferromagnetic interactions and subsequently to a spin glass state, which is reflected in the form of an additional $T$-linear contribution at low temperatures in specific heat. A clear evidence of Jahn-Teller distortion at the Co$^{3+}$-O$_6$ complex is observed and incorporating the physics of Jahn-Teller effect, the presence of localized magnetic moment is shown. A large, negative and anomalous magnetoresistance of $\approx$ 63% at 14K in 12T applied field is observed for Sr$_2$FeCoO$_6$. The observed magnetoresistance could be explained by applying a semi-empirical fit consisting of a negative and a positive contribution and show that the negative magnetoresistance is due to spin scattering of carriers by localized magnetic moments in the spin glass phase

Spin Freezing in the Spin Liquid Compound FeAl2O4

Spin freezing in the $A$-site spinel FeAl$_2$O$_4$ which is a spin liquid candidate is studied using remnant magnetization and nonlinear magnetic susceptibility and isofield cooling and heating protocols. The remnant magnetization behavior of FeAl$_2$O$_4$ differs significantly from that of a canonical spin glass which is also supported by analysis of the nonlinear magnetic susceptibility term $\chi_3 (T)$. Through the power-law analysis of $\chi_3 (T)$, a spin-freezing temperature, $T_g$ = 11.4$\pm$0.9~K and critical exponent, $\gamma$ = 1.48$\pm$0.59 are obtained. Cole-Cole analysis of magnetic susceptibility shows the presence of broad spin relaxation times in FeAl$_2$O$_4$, however, the irreversible dc susceptibility plot discourages an interpretation based on conventional spin glass features. The magnetization measured using the cooling-and-heating-in-unequal-fields protocol brings more insight to the magnetic nature of this frustrated magnet and reveals unconventional glassy behaviour. Combining our results, we arrive at the conclusion that the present sample of FeAl$_2$O$_4$ consists of a majority spin liquid phase with "glassy" regions embedded.Comment: 5 pages, 6 figs, 2-column, Accepted to Phys. Rev.

AirCode: Unobtrusive Physical Tags for Digital Fabrication

We present AirCode, a technique that allows the user to tag physically fabricated objects with given information. An AirCode tag consists of a group of carefully designed air pockets placed beneath the object surface. These air pockets are easily produced during the fabrication process of the object, without any additional material or postprocessing. Meanwhile, the air pockets affect only the scattering light transport under the surface, and thus are hard to notice to our naked eyes. But, by using a computational imaging method, the tags become detectable. We present a tool that automates the design of air pockets for the user to encode information. AirCode system also allows the user to retrieve the information from captured images via a robust decoding algorithm. We demonstrate our tagging technique with applications for metadata embedding, robotic grasping, as well as conveying object affordances.Comment: ACM UIST 2017 Technical Paper

Secure communication using dynamic VPN provisioning in an Inter-Cloud environment

Most of the current cloud computing platforms offer Infrastructure as a Service (IaaS) model, which aims to provision basic virtualised computing resources as on-demand and dynamic services. Nevertheless, a single cloud does not have limitless resources to offer to its users, hence the notion of an Inter-Cloud enviroment where a cloud can use the infrastructure resources of other clouds. However, there is no common framework in existence that allows the srevice owners to seamlessly provision even some basic services across multiple cloud service providers, albeit not due to any inherent incompatibility or proprietary nature of the foundation technologies on which these cloud platforms are built. In this paper we present a novel solution which aims to cover a gap in a subsection of this problem domain. Our solution offer a security architecture that enables service owners to provision a dynamic and service-oriented secure virtual private network on top of multiple cloud IaaS providers. It does this by leveraging the scalability, robustness and flexibility of peer- to-peer overlay techniques to eliminate the manual configuration, key management and peer churn problems encountered in setting up the secure communication channels dynamically, between different components of a typical service that is deployed on multiple clouds. We present the implementation details of our solution as well as experimental results carried out on two commercial clouds

Dynamic virtual private network provisioning from multiple cloud infrastructure service providers

The Cloud infrastructure service providers currently provision basic virtualized computing resources as on demand and dynamic services but there is no common framework in existence that allows the seamless provisioning of even these basic services across multiple cloud service providers, although this is not due to any inherent incompatibility or proprietary nature of the foundation technologies on which these cloud platforms are built. We present a solution idea which aims to provide a dynamic and service oriented provisioning of secure virtual private networks on top of multiple cloud infrastructure service providers. This solution leverages the benefits of peer to peer overlay networks, i.e., the flexibility and scalability to handle the churn of nodes joining and leaving the VPNs and can adapt the topology of the VPN as per the requirements of the applications utilizing its intercloud secure communication framework

Double-phase transition and giant positive magnetoresistance in the quasi-skutterudite Gd3_3Ir4_4Sn13_{13}

The magnetic, thermodynamic and electrical/thermal transport properties of the caged-structure quasi-skutterudite Gd$_3$Ir$_4$Sn$_{13}$ are re-investigated. The magnetization $M(T)$, specific heat $C_p(T)$ and the resistivity $\rho(T)$ reveal a double-phase transition -- at $T_{N1}\sim$ 10~K and at $T_{N2}\sim$ 8.8~K -- which was not observed in the previous report on this compound. The antiferromagnetic transition is also visible in the thermal transport data, thereby suggesting a close connection between the electronic and lattice degrees of freedom in this Sn-based quasi-skutterudite. The temperature dependence of $\rho(T)$ is analyzed in terms of a power-law for resistivity pertinent to Fermi liquid picture. Giant, positive magnetoresistance (MR) $\approx$ 80$\%$ is observed in Gd$_3$Ir$_4$Sn$_{13}$ at 2~K with the application of 9~T. The giant MR and the double magnetic transition can be attributed to the quasi-cages and layered antiferromagnetic structure of Gd$_3$Ir$_4$Sn$_{13}$ vulnerable to structural distortions and/or dipolar or spin-reorientation effects. The giant value of MR observed in this class of 3:4:13 type alloys, especially in a Gd-compound, is the highlight of this work.Comment: 20 pages single column, 7 figures, 1 table; Accepted to J. Appl. Phys., 201

Changes in the total protein, carbohydtate and lipid contents in selected tissues of silkworm, Bombyx mori L. under the influence of a juvenoid R394

Η νεανική ορμόνη R394 (ethyl 9-cyclohexyl-3,7-dimethyl-2,4-nonadienoate) εφαρμόστηκε τοπικά σε προνύμφες 5Π" σταδίου του μεταξοσκώληκα Bombyx mori L. (υβρίδιο: ΚΑ χ NB4D2) σε δόση 0,039η1/προνύμφη vta 24, 48, 72 και 96 ώρες, για την βελτίωση της παραγωγής μεταξιού. Επιλέχθηκαν τρεις κύριοι ιστοί, ο οπίσθιος μεταξογόνος αδένας (PSG). η αιμολέμφος και το λιπώδες σώμα, οι οποίοι συλλέχθηκαν από πλήρως αναπτυγμένες προ νύμφες και υπολογίστηκε η περιεκτικότητα τους σε ολικές πρωτεΐνες, ολίκούς υδατάνθρακες Kar ολικά λιπίδια. Το αποτέλεσμα έδειξε ότι η περιεκτικότητα των κύριων μεταβολιτών διέφερε σημαντικά στους παραπάνω ιστούς, ανάλογα με τον χρόνο εφαρμογής της νεανικής ορμόνης. Η υψηλότερη περιεκτικότητα σε πρωτεΐνες παρατηρήθηκε στην αιμολεμφο και το μεταξογόνο αδένα των προνυμφών που δέχτηκαν την επέμβαση για 72 ώρες, ενώ η περιεκτικότητα σε πρωτεΐνες του λιπώδους σώματος ήταν η μικρότερη στην ίδια μεταχείριση. Η χαμηλότερη ολική περιεκτικότητα σε υδατάνθρακες καταγράφηκε στις προνύμφες ποι> δέχτηκαν την επέμβαση για 72 ώρες, ενώ η υψηλότερη στον μάρτυρα τόσο στην αιμολεμφο όσο και στο λιπώδες σώμα, χωρίς να παρατηρείται σημαντική μεταβολή στον μεταξογόνο αδένα. Η ολική περιεκτικότητα σε λιπίδια δεν εμφάνισε αξιοσημείωτη παραλλακτικότητα κατά την εφαρμογή της νεανικής ορμόνης, με εξαίρεση τον μεταξογόνο αδένα σε προνύμφες που δέχτηκαν την επέμβαση για μέχρι 72 ώρες, όπου παρατηρήθηκε μείωση. Το αποτέλεσμα υποδηλώνει ότι η νεανική ορμόνη προκαλεί εξειδικευμένες για κάθε ιστό αντιδράσεις από άποψη μεταβολής της περιεκτικότητας σε κύριους μεταβολίτες, η οποία είναι ανάλογη με τις αντίστοιχες μεταβολές που παρατηρήθηκαν στο βάρος του βομβυκίου και το βάρος του κελύφους του βομβυκίου.A juvenoid. R394 (Ethyl 9-cyclohexyl-3,7-dimethyl-2,4-nonadienoate) was applied topically to 5th instar silkworm, Bombyx mori L. larvae (Hybrid: KA x NB4D2) at a dose of 0.039 nl/larva at 24, 48, 72 and 96 h, for silk yield improvement. Three major selected tissues viz., posterior silk gland (PSG), haemolymph and fat body were collected from fully-grown larvae and the total protein, total carbohydrate and total lipid contents were estimated following standard procedures. The result indicated that the content of these primary metabolites varied significantly in the selected tissues depending on the time of juvenoid application. The highest protein content was observed in the haemolymph and silk gland in the larvae treated at 72 h whereas the fat body protein content was lowest for the same treatment. The total carbohydrate was recorded lowest in the 72 h treated larvae as against the highest in the control both in haemolymph and fat body with no significant change in PSG. The total lipid content did not show any notable variation in the concentration on juvenoid administration except in the silk gland treated up to 72 h which showed a decline. The results indicate that the juvenoid induces tissue-specific responses in terms of turnover in primary metabolites which commensurates with the corresponding changes observed in the cocoon weight and cocoon shell weight