Cloud authorization: exploring techniques and approach towards effective access control framework

Despite the various attractive features that Cloud has to offer, the rate of Cloud migration is rather slow, primarily due to the serious security and privacy issues that exist in the paradigm. One of the main problems in this regard is that of authorization in the Cloud environment, which is the focus of our research. In this paper, we present a systematic analysis of the existing authorization solutions in Cloud and evaluate their effectiveness against well-established industrial standards that conform to the unique access control requirements in the domain. Our analysis can benefit organizations by helping them decide the best authorization technique for deployment in Cloud; a case study along with simulation results is also presented to illustrate the procedure of using our qualitative analysis for the selection of an appropriate technique, as per Cloud consumer requirements. From the results of this evaluation, we derive the general shortcomings of the extant access control techniques that are keeping them from providing successful authorization and, therefore, widely adopted by the Cloud community. To that end, we enumerate the features an ideal access control mechanisms for the Cloud should have, and combine them to suggest the ultimate solution to this major security challenge – access control as a service (ACaaS) for the software as a service (SaaS) layer. We conclude that a meticulous research is needed to incorporate the identified authorization features into a generic AcaaS framework that should be adequate for providing high level of extensibility and security by integrating multiple access control models.     

BOUNDARY ELEMENT–FINITE ELEMENT COUPLED EIGENANALYSIS OF FLUID–STRUCTURE SYSTEMS

The eigenanalysis of acoustical cavities with flexible structure boundaries, such as a fluid-filled container or an automobile cabin enclosure, is considered. An algebraic eigenvalue problem formulation for the fluid–structure problem is presented by combining the acoustic fluid boundary element eigenvalue analysis method and the structural finite elements. For many practical eigenproblems, use of finite elements to discretize the fluid domain leads to large stiffness and mass matrices. Since the acoustic boundary element discretization requires putting nodes only on the wetted surface of the structure, the size of the eigenproblem is reduced considerably, thus reducing the eigenvalue extraction effort. Futhermore, unlike in ordinary cases, the finite element discretization of pressure–displacement based fluid–structure problem gives rise to unsymmetric matrices. Therefore, the fact that the boundary element formulation produces unsymmetric matrices does not introduce additional difficulties here compared to the finite element case in the choice of an eigenvalue extraction procedure. Examples are included to demonstrate the fluid–structure eigenanalysis using boundary elements for the fluid domain and finite elements for the structure.     

Effect of recombinant human erythropoietin on insulin resistance in hemodialysis patients

Insulin resistance is a characteristic feature of uremia. Insulin resistance and concomitant hyperinsulinemia are present irrespective of the type of renal disease. Treatment with recombinant human erythropoietin (rHuEPO) was said to be associated with improvement in insulin sensitivity in uremic patients. The aim of this study was to compare insulin resistance in adult uremic hemodialysis (HD) patients including diabetic patients treated with or without rHuEPO. A total of 59 HD patients were studied, patients were divided into 2 groups of subjects: 30 HD patients on regular rHuEPO treatment (group A), and 29 HD patients not receiving rHuEPO (group B) diabetic patients were not excluded. Full medical history and clinical examination, hematological parameters, lipid profile, serum albumin, parathyroid horomone, Kt/V, fasting glucose, and insulin levels were measured in all subjects. Homeostasis Model Assessment of Insulin Resistance (HOMA‐IR) was used to compare insulin resistance. The results of this study showed that the mean insulin level of HD patients treated with rHuEPO (group A) (17.5 ± 10.6 μU/mL) was significantly lower than patients without rHuEPO (group B) (28.8 ± 7.7 μU/mL), (P<0.001). Homeostasis Model Assessment of Insulin Resistance levels in group A were significantly lower than in group B (3.8 ± 2.97, 7.98 ± 4.9, respectively, P<0.001). Insulin resistance reflected by HOMA‐IR levels among diabetic patients in group A was significantly lower than among diabetic patients in group B (3.9 ± 3.2, 9.4 ± 7.2, respectively, P<0.001). Also, HOMA‐IR levels among nondiabetic patients in group A were significantly lower than among nondiabetic patients in group B (3.7 ± 2.85, 6.9 ± 1.43, respectively, P<0.01). We found a statistically significant negative correlation between duration of erythropoietin treatment, fasting blood glucose, insulin levels, and insulin resistance (r=?0.62, ?0.71, and ?0.57, P<0.001). Patients treated with rHuEPO showed less insulin resistance compared with patients not treated with rHuEPO in diabetic and nondiabetic patients and, duration of erythropoietin treatment is negatively correlated with insulin levels and insulin resistance in HD patients.     

D.C. conductivity and spectroscopic studies of polyaniline doped with binary dopant ZrOCl<Subscript>2</Subscript>/AgI

Aqueous binary dopant (ZrOCl₂/AgI) is used in different ratios such as 1:1, 1:2 and 2:1 (w/w) for chemical doping to enhance the conductivity of synthesized polyaniline (PANI). The doping of polyaniline is carried out using tetrahydrofuran as a solvent. Doped samples are characterized using various techniques such as I–V characteristics, UV-visible spectroscopy, X-ray diffractometry (XRD), FTIR and photoluminescence (PL) studies. A significant enhancement in d.c. conductivity has been observed with the introduction of binary dopant. UV-visible study shows that optical parameters change considerably after doping. Interestingly, both direct and indirect bandgaps are observed in the doped samples. XRD patterns show the semi-crystalline nature of doped polyaniline. FTIR study shows structural modifications in functional groups with doping in PANI. Photoluminescence spectra exhibit emission properties of the samples.     

Feature Recognition in Solar Images

Despite several decades of research and development in the field of pattern recognition, the general problem of recognizing complex patterns with arbitrary orientations, locations, and scales remains unsolved and normally is applied using iterative manual evaluation of the detection results. This problem is becoming increasingly important with the growing number of massive archives of solar images produced by instruments located at ground-based observatories and aboard current satellites such as YOHKOH, SOHO and TRACE, with future satellites such as SOLAR B, SDO and STEREO in prospect. The size of expected archives requires a new automated approach to digital image processing and data extraction with robust and efficient pattern recognition techniques to be developed and implemented. This review evaluates techniques for the standardisation in shape and intensity of solar images and summarises the existing manual and semi-automated feature recognition techniques applied to a representative range of solar features, including sunspots, filaments, active regions, flares, coronal mass ejections and magnetic neutral lines. The review also surveys the most recent fully-automated detection techniques developed for the creation of Solar Feature Catalogues of sunspots, active regions and filaments for the European Grid of Solar Observations. The survey is aimed to help researchers and students to learn about the recognition techniques applied to astrophysical images with different levels of noise and distortions and to work effectively with the Solar Feature Catalogue.     

Output-feedback control with almost-disturbance-decoupling property—a singular perturbation approach

For square invertible and minimum-phase linear time-invariant systems, a high-gain observer-based control law is proposed. This control law provides internal stability for the closed-loop system and has the almost-disturbance-decoupling properly: that is, the influence of the disturbances on the controlled output can be made arbitrarily small.     

Bi-objective min-flow problem with capacity and flow constraints

A network flow algorithm for a bi-criteria version of the manpower scheduling and resource allocation problem is developed. In such a study it is desired to find the ‘minimum’ total ‘flow’ through the network, where ‘flow’ is represented by a two-component cost vector and ‘minimum’ is interpreted in the sense of a vector-minimum. Thus, a set of non-dominated solutions is obtained. The method efficiently generates both individual (criterion) optima and bi-criteria solutions in a single pass. A simple example is presented.