Security and Privacy Issues in Cloud Computing

Cloud computing transforming the way of information technology (IT) for consuming and managing, promising improving cost efficiencies, accelerate innovations, faster time-to-market and the ability to scale applications on demand (Leighton, 2009). According to Gartner, while the hype grew ex-ponentially during 2008 and continued since, it is clear that there is a major shift towards the cloud computing model and that the benefits may be substantial (Gartner Hype-Cycle, 2012). However, as the shape of the cloud computing is emerging and developing rapidly both conceptually and in reality, the legal/contractual, economic, service quality, interoperability, security and privacy issues still pose significant challenges. In this chapter, we describe various service and deployment models of cloud computing and identify major challenges. In particular, we discuss three critical challenges: regulatory, security and privacy issues in cloud computing. Some solutions to mitigate these challenges are also proposed along with a brief presentation on the future trends in cloud computing deployment

Modal analysis of wave propagation in dispersive media

Surveys on wave propagation in dispersive media have been limited since the pioneering work of Sommerfeld [Ann. Phys. 349, 177 (1914)] by the presence of branches in the integral expression of the wave function. In this article, a method is proposed to eliminate these critical branches and hence to establish a modal expansion of the time-dependent wave function. The different components of the transient waves are physically interpreted as the contributions of distinct sets of modes and characterized accordingly. Then, the modal expansion is used to derive a modified analytical expression of the Sommerfeld precursor improving significantly the description of the amplitude and the oscillating period up to the arrival of the Brillouin precursor. The proposed method and results apply to all waves governed by the Helmholtz equations.Comment: 10 pages, 9 figure

Glyphosate reduced seed and leaf concentrations of calcium, manganese, magnesium, and iron in non-glyphosate resistant soybean

Greenhouse experiments were conducted to study the effects of glyphosate drift on plant growth and concentrations of mineral nutrients in leaves and seeds of non-glyphosate resistant soybean plants (Glycine max, L.). Glyphosate was sprayed on plant shoots at increasing rates between 0.06 and 1.2% of the recommended application rate forweed control. In an experiment with 3-week-old plants, increasing application of glyphosate on shoots significantly reduced chlorophyll concentration of the young leaves and shoots dry weight, particularly the young parts of plants. Concentration of shikimate due to increasing glyphosate rates was nearly 2-fold for older leaves and 16-fold for younger leaves compared to the control plants without glyphosate spray. Among the mineral nutrients analyzed, the leaf concentrations of potassium (K), phosphorus (P), copper (Cu) and zinc (Zn) were not affected, or even increased significantly in case of P and Cu in young leaves by glyphosate, while the concentrations of calcium (Ca), manganese (Mn) and magnesium (Mg) were reduced, particularly in young leaves. In the case of Fe, leaf concentrations showed a tendency to be reduced by glyphosate. In the second experiment harvested at the grain maturation, glyphosate application did not reduce the seed concentrations of nitrogen (N), K, P, Zn and Cu. Even, at the highest application rate of glyphosate, seed concentrations of N, K, Zn and Cuwere increased by glyphosate. By contrast, the seed concentrations of Ca, Mg, Fe and Mn were significantly reduced by glyphosate. These results suggested that glyphosatemay interfere with uptake and retranslocation of Ca, Mg, Fe and Mn, most probably by binding and thus immobilizing them. The decreases in seed concentration of Fe, Mn, Ca and Mg by glyphosate are very specific, and may affect seed quality

Optimisation of thermal output for an SMA-based heat pump

As countries transition to a low carbon economy, there are sizable environmental and economic benefits from developing and using efficient, innovative, low carbon heating and cooling technologies that have the potential to reduce energy use and carbon emissions. This thesis focuses on elastocaloric refrigeration technology and ways of enhancing the thermal outputs of Shape Memory Alloys (SMA), which are the core material of the technology. The thesis includes an up-to-date and comprehensive critical review and evaluation of recent advances in emerging alternative heating and cooling technologies that have the potential to reduce the environmental impacts of the refrigeration, air-conditioning and heat-pumps (RACHP) sector. The literature review on elastocaloric refrigeration showed that all the designed and manufactured prototypes to date either work under tension or under compression for pipes. The experiments also showed that using tension loading for a heat pump device is not practical despite its excellent heat transfer potential, as the material under tension tends to deform permanently much quicker, since the cracks on the surface of the material tend to grow and propagate and thus leading to failure; moreover, tension loading is limited to stress between 100 MPa to 200 MPa. On the other hand, although compressive loading requires specific geometric configurations to avoid failuressuch as buckling, it has a longer fatigue life, because the impurities and cracks do not grow and propagate; moreover, compression loading can exceed stresses of 1000 MPa allowing for better material performance. To overcome the challenges as identified and stated in the literature, it was necessary to establish a thorough understanding of the designated material properties with the aid of COMSOL MULTIPHYSICS modelling. This included looking at methods of altering the material's characteristics by means of heat-treatment, as well as using material characterization equipment to achieve improved thermal outputs. Moreover, the research focused on proposing and studying a range of novel geometric designs and configurations for the material. The best performing configuration was established, and this led to designing the SMA-heat-pump stack and the fluid flow paths. Also, the research focused on modelling the working fluids in COMSOL MULTIPHYSICS to establish the most appropriate means of enhancing their thermal properties. The first base-fluid to be tested was water, of which was followed by adding 1%, 2% and then 3% concentrations of Graphene Oxide nanoparticles to compose new nanofluids that had improved thermal properties. The research included a study of the relationship between the stress and strain, the temperature lift, and the available latent heat. Since the potential design was to stack the plates and compress them, the results showed that applying a compressive loading of 500 MPa on an SMA specimen resulted in a 1.63% of material’s deformation, a 10K temperature lift, and 1.46 \u1d43d. \u1d454−1 of latent heat. When the applied compressive loading was increased to 900 MPa, the material deformed by 5.4% and in so doing achieved a 19K temperature lift and 19 \u1d43d. \u1d454−1 of latent heat. On the plate design front, the results showed that the rectangular shape channels/fluid-path provided the highest Reynolds number which led to higher heat transfer coefficient; and as a result, it was possible to extract 98% of the available heat within the plate. On the fluids front, the results showed that the channel/ flow-path has different temperatures at different heights, and it was found that there is a lag between the increase of the material’s temperature and that of the fluid. It was also found that water achieved a temperature span of 2.8K; however, when 1%, 2% and 3% concentrations of the nanoparticles were added to water, the newly formed nanofluids had better thermal properties, as their thermal conductivity increased by 52%, 59% and 65% respectively, and because of that the temperature lift increased by 25.9% and the loading cycle was shortened by 24% with the third nanofluid (water plus 3% of Graphene Oxide), which will have a positive impact on the compactness and the cost of the SMA core. This research has contributed to knowledge through the following: ✓ Providing a roadmap for SMA modelling in CFD (COMSOL MULTIPHYSICS) and how SMA is susceptible to different applied stresses and cycle times. ✓ Providing a roadmap of how to design different SMA geometries that can withstand high stresses and thus could potentially be used as the core material for an SMA-based heat pump device without encountering material failure due to high stresses. ✓ Developing an innovative approach to enhance the heat transfer from SMA through using enhanced nanofluids

Collider Effects of Unparticle Interactions in Multiphoton Signals

A new model of physics, with a hidden conformal sector which manifests itself as an unparticle coupling to Standard Model particles effectively through higher dimensional operators, predicts strong collider signals due to unparticle self-interactions. We perform a complete analysis of the most spectacular of these signals at the hadron collider, pp -> 4photon and pp ->2photon,2gluon. These processes can go through the three-point unparticle self interactions as well as through some s and t channel diagrams with one and/or two unparticle exchanges. We study the contributions of individual diagrams classified with respect to the number of unparticle exchanges and discuss their effect on the cross sections at the Tevatron and the LHC. We also restrict the Tevatron bound on the unknown coefficient of the three-point unparticle correlator. With the availability of data from Tevatron, and the advent of the data emerging from the LHC, these interactions can provide a clear and strong indication of unparticle physics and distinguish this model from other beyond the standard model scenarios.Comment: 28 pages, 16 figure