New attacks on secret sharing-based data outsourcing: toward a resistant scheme

In this paper, two new practical attacks on some secret sharing-based data outsourcing schemes are first introduced, and several other security and performance issues with the existing schemes are also explored. The existing and new attacks exploit the information about the share range boundaries or the correspondences between the secret values and shares. A range expansion technique is then proposed to thwart one of the attacks. It expands the ranges in every range predicate in the submitted queries in order to hide the share range boundaries from any query observer. Next, a mapping method is proposed to thwart the other attacks. It maps each secret value to a mapping value using a secret one-to-many mapping with a finite set of linear mapping rules so that the tuples of shares are generated from the mapping values rather than directly from the secret values. The proposed mapping method works as an additional layer of security and addresses any attack based on the correspondences between the secret values and shares. At the same time, it preserves the homomorphism property of secret sharing. Finally, a new secure data outsourcing scheme is elaborated on secret sharing, the proposed mapping method, and the proposed range expansion technique. The proposed scheme is resistant to various attacks and also some inferences. It supports the fully server-side or a partially server-side query execution of most types of queries. The experimental results confirm that the proposed scheme is quite practical and efficient.

     

Deployment of real-time systems in the cloud environment

Interest in real-time systems has grown considerably over recent years, primarily due to significant increase in the use of smart technologies and latency-sensitive applications such as cloud gaming, audio/video streaming, and smart homes. Significant work has been done on resource mapping in the cloud environment, and a number of promising results have been established accordingly where the focus is mainly on resource provisioning. However, the applicability of cloud computing services for real-time systems generated from smart systems is still in its infancy and remains unexplored, relatively. To address this gap, we propose a model for the smart systems that periodically offload computational workload to the cloud environment where virtual machines are allocated according to rate-monotonic scheduling policy to ensure requests are processed within the associated deadlines. Deadlines of tasks have been relaxed to improve server utilization as well as maintain a level of confidence in the timing constrains. Experimental results are discussed to highlight the applicability of static priority assignment for the workload in the context of virtual machines allocation.

     

A New Method of Eddy Diffusivity Calculation for Droplets of a Venturi Scrubber

An analytical model using eddy diffusivity is applied for predicting droplet concentration distribution and liquid film formation in a Venturi scrubber. By comparing experimental data of film formation reported in literature (Viswanathan et al., 1984) and the results obtained from this model, a semi‐empirical correlation for liquid droplets eddy diffusivity is obtained. The validity of this correlation is confirmed by obtaining good agreement between theoretical and experimental data of droplet concentration distribution and film formation in a Venturi scrubber (Viswanathan, 1998; Viswanathan et al., 1984).     

MATHEMATICAL MODELING OF HEAT AND MASS TRANSFER IN HOT GAS SPRAY SYSTEMS

A mathematical model is developed to study simultaneous heat and mass transfer in hot gas spray systems. The model is obtained by writing mass, energy, and momentum balances for both continuous and discontinuous phases. Governing equations along with suitable correlations for heat and mass transfer coefficients have been solved numerically. In order to develop a realistic model for such complicated systems, a droplet size distribution was implemented in the model instead of using an average size. A steady state spray-cooling problem is analyzed to illustrate the applicability of the model. To validate the mathematical model for this case, necessary data was collected and measured in commercial cement plants. A good agreement between plant data and the model was noticed in general, and results obtained from the model indicate that size distribution of water droplets and physical dimensions of the spray-cooling system are important parameters. This model is very useful in determining the so-called "critical operation condition" at which sludge formation at the bottom of spray-cooling systems will happen. The predicted parameters in spray-cooling systems both for droplet phase and gas phase aptly illustrate the ability of the model to treat the complex phenomena associated with two-phase flows.     

Energy Broadening Model for BGO Array Crystal from 0.059 to 1.332 MeV

The energy resolution and energy broadening parameters are of great importance as far as scintillator detector is concerned. At present, BGO crystal due to its high density, high yield of photoelectric absorption, availability and cost is used in particle physics and medical imaging system especially in positron emission tomography (PET). The purpose of this study is to calculate the Gaussian energy broadening parameters of a 10 × 10 BGO array in order to use it in simulation for analysis of its spectral response in the presence of gamma rays in a wide range of energies. The Gaussian energy broadening parameters were extracted from the experimental spectrum to use them as the input parameters in MCNP4c code. The simulated response of the detector employing these parameters showed a good agreement with the experimental data.     

Slot Numbering and Distributed Winding Effects Analysis on the Torque/Current Spectrum of Three-phase Wound-rotor Induction Machine Using Discrete Modeling Method

Smooth torque production by induction machines is an improbable phenomena that is taken into account only in classic and ideal studying methods. In this research, slot numbering and also non-sinusoidal winding function effects are studied for a three-phase wound-rotor induction machine, which is addressed for the first time, and a new formula is introduced for calculating the spectral components of machine torque and current. To reach this aim, mathematical modeling of the air-gap function is proposed, and a discrete time modeling of the machine is introduced to study the effects of space harmonics on the torque/current spectral. To study the mentioned phenomena, in the first part, the winding functions are considered as ideally sinusoidal and the behavior of simulated machines is investigated based on the winding function approach and numerical method analysis. Two certain formulas are introduced for the spectral components of torque ripple and stator currents according to the slot numbers, rotor speed, and number of machine poles. In the second part, slot opening effects are neglected and non-sinusoidal windings are considered for obtaining the same results. Finally, considering both effects, model validation is confirmed by a finite-element-based method, and the introduced method is proven.     

Adaptive trajectory tracking control of wheeled mobile robots with disturbance observer

In this paper, the trajectory tracking problem for a wheeled mobile robot in the presence of kinematic and dynamic uncertainties has been addressed. Uncertainties are modeled as lumped disturbances. A kinematic controller based on feedback linearization approach and a dynamic controller based on model reference adaptive control are designed in the presence of disturbances. In order to ensure both robustness and implementability of the controllers, the disturbances are estimated by a generalized linear matrix inequality‐based disturbance observer. Simulation results show the effectiveness of the proposed method. Copyright © 2013 John Wiley & Sons, Ltd.     

Segmental dynamics of reactively prepared polystyrene blends: Unsaturated polyester resin versus high impact polystyrene

Segmental dynamics of two phase‐separated reactively prepared polystyrene blends namely unsaturated polyester resin (UPR) and high impact polystyrene (HIPS) was investigated by dynamic–mechanical spectroscopy and calorimetric studies. The results showed a thermorheologically simple behavior for the HIPS, which could be quantified based on the KWW function with β_KWW of 0.37. The UPR data, however, could not be evaluated using KWW function, even though lower β_KWW than the HIPS was expected for it. Furthermore, the α‐dispersion of the UPR was considerably broader while its fragility index was comparable with the HIPS. Nonetheless, segmental dynamics comparison based on normalized ΔC_p(T_g) by molecular weight of the structural units of the studied systems showed much greater differences. Accordingly, the UPR was both kinetically and thermodynamically more fragile than the HIPS. The higher fragility of the UPR could be attributed to its larger relative cooperativity size and topological constraints. Finally, enhanced contrast in dynamic fragilities of two studied systems could be achieved if similar overall and local compositions could be made experimentally. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

The Effect of Fullerene C60 and its Amine Derivative on the ZDDP Antioxidative Functionality

In this work we describe the effect of both fullerene and its oil-soluble amine derivative on antioxidative properties of ZDDP (zinc dialkyldithiophosphate, alky groups: isobutyl and isoamyl). An oxidation reaction in the presence of AIBN (as an initiator) was chosen as chemical probe to investigate mutual interaction of ZDDP with fullerene and its derivative. According to the experimental results, both fullerene C₆₀ and its amine derivative show more antioxidative properties than ZDDP. Experimentally, it is concluded that the presence of these species increase the effect of ZDDP as antioxidant. This effect could be experimentally described in terms of the metal center of ZDDP.