High-dimensional multimedia classification using deep CNN and extended residual units

Multimedia Tools and Applications - Processing multimedia data has emerged as a key area for the application of machine learning methods Building a robust classification model to use in high...     

An improved low-cost yoking proof protocol based on Kazahaya’s flaws

Peris-Lopez et al. (J Netw Comput Appl 34:833–845, 2011) recently provided some guidelines that should be followed to design a secure yoking proof protocol. In addition, conforming to those guidelines and EPC C1-G2, they presented a yoking proof for medical systems based on low-cost RFID tags, named Kazahaya. In this paper, we compromise its security and show how a passive adversary can retrieve secret parameters of a patient’s tag in cost of \(O(2^{16})\) off-line PRNG evaluations. Nevertheless, to show other weaknesses of the protocol and rule out any possible improvement by increasing the length of the used PRNG, we present a forgery attack that proves that a generated proof at time \(t_n\) can be used to forge a valid proof for any desired time \(t_j\). The success probability of this attack is ‘1’ and the complexity is negligible. In addition, we present a new lightweight protocol based on 128-bit PRNG function to solve the problems of Kazahaya protocol. In terms of security, we evaluate the new protocol based on formal and informal methods and prove that the improved protocol is not vulnerable to RFID attacks.     

Cryptanalysis of a new EPC class-1 generation-2 standard compliant RFID protocol

EPC class 1 Generation-2 (or in short term EPC-C1 G2) is one of the most important standards for RFID passive tags. However, the original protocol is known to be insecure. To improve the security of this standard, several protocols have been proposed which are compliant to this standard. In this paper, we analyze the security of a protocol which has been recently proposed by Lo and Yeh (2010). Despite the designers’ claim, which is optimal security, however, we present a passive attack which can retrieve all secret parameters of the tag efficiently. The cost of this attack is eavesdropping only one session of protocol between the tag and a legitimate reader and 2¹⁶ PRNG-function evaluations in off-line. In addition, we show that an active adversary can retrieve secret parameters more efficiently, that is, with the complexity of two consequence sessions of protocol and without the need for PRNG-function evaluation. The success probability of the given attacks are “1”. To counteract such flaws, we propose an enhanced EPC-compliant protocol entitled YAYA, by applying some minor modifications to the original protocol so that it provides the claimed security properties.     

Investigation and Comparing the Effects of CNTs and Ag Nanoparticles Doping on YBCO Superconductor Properties

In this work, we investigate and compare doping effects of Ag nanoparticles and carbon nanotubes (CNTs) on the properties of Y₁Ba₂Cu₃ O _7?δ (YBCO) high-temperature superconductor. The YBCO samples were prepared using sol-gel method and characterized by resistivity versus temperature (ρ–T), the electrical field versus current density (E–J), x-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. The results show that the orthorhombic phase of superconductivity was formed for all the prepared samples. Also, we found that the crystalline size of the YBCO samples decreases from 62 to 33 nm by adding CNTs and Ag nanoparticles to the compound. The pinning energy, critical current density and critical temperature of the samples increase by adding CNTs and Ag nanoparticles to YBCO compound, but CNTs play a more effective role than Ag nanoparticles in this compound.     

Imaging Heterogeneously Distributed Photo‐Active Traps in Perovskite Single Crystals

Organic–inorganic halide perovskites (OIHPs) have demonstrated outstanding energy conversion efficiency in solar cells and light‐emitting devices. In spite of intensive developments in both materials and devices, electronic traps and defects that significantly affect their device properties remain under‐investigated. Particularly, it remains challenging to identify and to resolve traps individually at the nanoscopic scale. Here, photo‐active traps (PATs) are mapped over OIHP nanocrystal morphology of different crystallinity by means of correlative optical differential super‐resolution localization microscopy (Δ‐SRLM) and electron microscopy. Stochastic and monolithic photoluminescence intermittency due to individual PATs is observed on monocrystalline and polycrystalline OIHP nanocrystals. Δ‐SRLM reveals a heterogeneous PAT distribution across nanocrystals and determines the PAT density to be 1.3 × 10¹⁴ and 8 × 10¹³ cm^?3 for polycrystalline and for monocrystalline nanocrystals, respectively. The higher PAT density in polycrystalline nanocrystals is likely related to an increased defect density. Moreover, monocrystalline nanocrystals that are prepared in an oxygen‐ and moisture‐free environment show a similar PAT density as that prepared at ambient conditions, excluding oxygen or moisture as chief causes of PATs. Hence, it is concluded that the PATs come from inherent structural defects in the material, which suggests that the PAT density can be reduced by improving crystalline quality of the material.     

Performance evaluation of a new micro gas cyclone using simulation and experimental studies to capture indoor fine particles

The aim of this study was evaluating a micro gas cyclone performance with a body diameter of 10?mm to collect indoor fine particles. The design of a cyclone requires minimizing the pressure drop and maximizing the separation efficiency. Overall and grade efficiencies, pressure drops, and cut sizes have been investigated through a theoretical model, simulation, and experimental studies. The experimental part was conducted using an Electrical Low-Pressure Impactor (ELPI) device to measure particle concentration for flow rates of 10–13.3 (l/min). In order to study the pressure drop and velocity behavior for different flow rates, COMSOL software was utilized. The obtained results from experimental work have met the theoretical and simulation outcomes adequately. It has been confirmed by all the obtained results that by increasing the flow rate and subsequently inlet velocity, the particle collection efficiency and pressure drop increase while the cut size decreases.     

Micelle mediated extraction and simultaneous spectrophotometric determination of vanadium(V) and molybdenum(VI) in plant foodstuff samples

A micelle-mediated extraction method for preconcentration of trace quantities of V(V) and Mo(VI) as a prior step to their simultaneous spectrophotometric determination has been developed. Bromopyrogallol red, cetyltrimethylammonium bromide (CTAB) (cationic surfactant) and KI were used as chelating, extraction and co-extraction agents, respectively.     

Investigation of factors affecting on viscosity reduction of sludge from Iranian crude oil storage tanks

Crude oil is a kind of water/oil emulsion, which the oil phase consists of organic molecules with different molecular weights such as alkanes, paraffin, asphaltene, and resins. Due to the change in physicochemical conditions during the production, transportation, storage, and refining, heavier molecules can precipitate from crude oil. Thus, viscous sludge formed at the bottom of storage tanks can cause many problems including reduction of storage capacity of tank, oil contamination, corrosion, repair costs, environmental pollution, etc. The reduction of sludge viscosity can be achieved by reduction of its interfacial tension. In this study, different chemical and physical factors, influencing prepared emulsions (made of sludge, water and surfactant), such as surfactants, solvents, temperature, pressure, and mixing conditions were investigated. Results showed that non-ionic surfactants (like bitumen emulsifier), and solvents (such as mixed xylene, AW-400, and AW-402), injection of additives, applying pressure, and mixing operations had a positive effect on reduction of emulsion viscosity. All experiments were carried out with sludge obtained from crude oil storage tanks at Kharg Island, Iran.     

Synthesis and characterization of conductive neural tissue engineering scaffolds based on urethane-polycaprolactone

Polymeric biomaterials play a key role in enhancement of lengthy nerve regeneration and various types of scaffolds were used to pave the way for nerve regeneration. Electrospun fibrous scaffolds have special potential applicability in controlling the cell behaviors such as adhesion, growth, proliferation and function. This study attempted to design a conductive and porous fibrous scaffold containing polycaprolactone (PCL) and polyaniline (PANI) with controllable degradation rate by adding urethane groups in scaffold structures. FTIR and NMR analysis was used to characterize the chemical bonds. Morphology, porosity, conductivity and degradation rate of scaffolds were also evaluated. To assess the cell–scaffold interaction, PC-12 cell line was cultured on the scaffolds. Results showed that the degradation rate of composite samples significantly increased in 50 time period. It seems that these results suggest that the composite fibrous scaffolds having proportions of UPCL/PCL/PANI45:20:35 exhibit the most balanced properties that meet all of the required specifications for neural cells and possess a potential application in neural tissue engineering.     

Hydrothermal synthesized AZO Nanorods layer as a high potential buffer layer for inverted polymer solar cell

In this study, the performance of inverted polymer solar cell was improved using optically and electrically tuned Zn_1-xAl_xO (x?=?0, 0.005, 0.01 and 0.015) nanorods (AZO) as a high potential electron transporting layer. AZO nanorods with different compositions were synthesized using facile, low temperature, and low cost hydrothermal method that was confirmed by energy dispersive x- ray spectroscopy (EDS) analysis. As revealed, the optical transmittance and optical band gap increased by increasing the Al concentration in AZO nanorods. The fabricated device with ITO/Zn_1-xAl_xO nanorods / P₃HT: PCBM /WO₃/Ag structure showed ascending trend for its short-circuit current density (J_sc) by increasing the amount of Al doping. The inverted polymer solar cell with 1% Al doped ZnO nanorods showed a power conversion efficiency of 3.64% that is around 40% higher than that of the device with pure ZnO nanorods (2.58%). The performance enhancement was attributed to the combined effects of the improvement in charge collection and the higher optical transmittance of AZO in the visible range.