Efficient multisecret sharing scheme using new proposed computational security model

A multisecret sharing (MSS) is a method for sharing a set of secrets among some participants. They can recover each of these secrets without endangering the other secrets. Two kinds of security models have been proposed for MSS schemes. These models are categorized into 2 types. The first security model is unconditional security. This approach decreases the efficiency of MSS schemes. Therefore, the second type of security, which is more relaxed, appeared. This approach is called computational security. In this paper, with 2 examples, we will show that the current definition of computational security does not satisfy all of our expectations from a secure MSS scheme. In fact, in these examples, recovering a secret leaks information to the other secrets while these schemes are considered secure in view of the computational security. After determining the shortcomings of the current security definition, we propose a new definition for computational security and present an MSS scheme that enjoys rigorous proof of security in terms of the new definition. In addition, a complete comparison in terms of share size, number of public values, and required operations for recovering a secret between our scheme and previous schemes indicates that the presented scheme is efficient.     

Application of self-collimated beams in realizing all-optical photonic crystal-based half-adder

In this paper an all-optical half-adder was proposed by using self-collimation effect in two-dimensional photonic crystals. Self-collimation effect was obtained in XM direction for wavelength 1500 nm by using square lattice rod-type photonic crystal structure. Plane wave expansion and finite-difference time-domain methods were used to obtain the band structure diagram and simulate the optical behavior of the proposed structure, respectively. The maximum delay time and required input intensity are 1 ps and 54 mW/μm², respectively. The normalized power-level margins for logics 0 and 1 were obtained to be about 20 and 70%, respectively. The total footprint of the structure is about 75 μm², which is suitable for all optical integrated circuits.     

Seismic geomorphology and stratigraphic trap analyses of the Lower Cretaceous siliciclastic reservoir in the Kopeh Dagh-Amu Darya Basin

Lower Cretaceous Shurijeh–Shatlyk Formations host some of the main reservoirs in the Kopeh Dagh-Amu Darya Basin.Exploration in this area so far has focused on the development of structural traps, but recognition of stratigraphic traps in this area is of increasing importance. Integration of 3D seismic data with borehole data from thirteen wells and five outcrop sections was used to identify potential reservoir intervals and survey the hydrocarbon trap types in the East Kopeh Dagh Foldbelt(NE Iran). Analyses of horizontal slices indicated that the lower Shurijeh was deposited in a braided fluvial system.Generally, three types of channel were identified in the lower Shurijeh Formation: type 1, which is low-sinuosity channels interpreted to be filled with non-reservoir fine-grained facies; type 2, which is a moderately sinuous sand-filled channel with good prospectively; and type 3, which is narrow, high sinuosity channel filled with fine-grained sediments. Results indicate that upper Shurijeh–Shatlyk Formations were deposited in fluvial to delta and shallow marine environments. The identified delta forms the second reservoir zone in the Khangiran Field. Study of the stratigraphic aspects of the Shurijeh succession indicates that both lower and upper Shurijeh reservoirs are stratigraphic reservoir traps that improved during folding.     

Cramer-Rao lower bound on locations of sudden changes in a steplikesignal

Estimation of locations of sudden changes in a steplike signal has many signal processing applications; e.g., well-log signal segmentation, ionic-channel signal classification, edge detection, and segmentation of images. In this work, the Cramer-Rao lower bound (CRLB) on locations of steps in one-dimensional (1-D) steplike signals is calculated. The calculation is based on the use of a sigmoidal function to model a sudden-change (step) in the signal. The introduced model has an adjustable parameter that can be used to fit the CRLB calculation to a particular class of steplike signals     

利用核函数法中的自适应带宽同时对一维空间两个储集层属性参数进行粗化

在多孔介质流体流动模拟中,应用网格粗化方法必须在保留重要储集层参数的空间分布的前提下,首先利用大网格粗化原始地质模型(尤其是孔隙型介质),并用数值方法求解。提出了根据属性参数的空间分布、以核函数的自适应带宽为基础的网格粗化新方法,该方法既减少了网格数量,同时也保留原始精细模型的主要非均质性特征。该方法的关键点在于可以同时对两种储集层属性参数进行网格粗化。首先计算每个储集层属性参数的带宽量或最优门槛值并得到粗化结果,然后根据最大带宽和最小带宽采用两种不同的方法对两个属性参数同时粗化。现在已经能够实现利用不同方法建立储集层两个属性参数的最终粗化模型,不同方法的网格单元数和网格位置都相同。最小带宽法的粗化误差小于最大带宽法。图6表1参29     

Determining the occurrence time of different stages of asphaltene aggregation using molecular dynamics simulations

This work presents a framework for future studies to better understand the appropriate time to include chemical inhibitors at different stages of asphaltene aggregation in the oil. For this purpose, molecular dynamics (MD) simulations were performed to study the aggregation of asphaltene molecules in heptane, in terms of strength, dynamics, and the occurrence time of each stage of aggregation from single molecules to a large flocculate. Results indicate that the nucleation of nanoaggregates begins prior to 10?ns, clusters start forming at 98?ns, and flocculation happens after 120?ns. It was also observed that the final flocculate had a globular shape.     

Biochemical and molecular characterization of novel PAH-degrading bacteria isolated from polluted soil and sludge

Polycyclic aromatic hydrocarbons (PAHs) containing more than three rings are mainly less biodegradable. Therefore, the isolation of PAHs-degrading bacteria is of great importance to be augmented for bioremediation of polluted sites with PAHs. PAHs-degrading bacteria were isolated from contaminated sites of an oil refinery. The strains were confirmed by biochemical tests and 16S rRNA, which were Stenotrophomonas maltophilia (two strains), Thermomonas koreensis (three strains), Achromobacter (two strains), Pseudomonas stutzeri (one strain), Azospirillum brasilense (one strain) and Brevibacillus brevis (one strain). The isolate strains can be applied as a bacterial consortium for purification of polluted soil with high levels of PAHs.     

An exhaustive criterion for estimating quality of images in electrical impedance tomography with application to clinical imaging

This study proposes a versatile criterion for estimating quality of images in electrical impedance tomography. The point spread function (PSF) is calculated throughout the domain based on the scattering of energy as responses to a small anomaly spirally moved from the centre to the boundary. The proposed PSF is a measure of weighted spatial variance (WSV) of the conductivity over the whole domain. For each element, the weighting factor is a normalized multiplication of the area of that element by its square intensity. The WSV collectively incorporates all image attributes, i.e., spatial resolution, artifact, amplitude response, positioning error and shape deformation. The location of artifacts, which significantly influences reconstructed images in reality, is taken into account as well. The results illustrate that the proposed measure is more tolerant than existing criteria in evaluating performance of EIT systems in both theory and practice.     

A Statistical Model for Early Detection of DDoS Attacks on Random Targets in SDN

Wireless Personal Communications - Software Defined Networks (SDNs) have accelerated and simplified the management, configuration and error detection in today’s networking systems. However,...     

A novel algorithm to study the impact of the mismatch on analog building blocks: a case study in basic 35 nm CMOS amplifiers

In this paper, the context of modeling of the impact of mismatch and statistical variations on analogue circuit building blocks is emphasized. The aim is to develop a new algorithm which predicts the statistical behavior of important parameters of an amplifier including output resistance, voltage gain and trans-conductance. The relative error of standard deviation of statistical parameters will remain less than 5% compared with the most accurate Monte-Carlo (MC) simulations using atomistic library model-cards. In comparison with other models which are based on the normal distribution of parameters, the proposed model does not need this limiting presumption. On the other hand, the proposed algorithm is more efficient compared with time consuming MC atomistic simulations.