Defending Against Flooding Attacks in Mobile Ad-Hoc Networks Based on Statistical Analysis

Wireless Personal Communications - Due to their specific structure and plenty of their utilization, mobile ad-hoc networks are vulnerable to various attacks. An attack which impacts on network...     

Triple‐faced polypropylene: Fire retardant,thermally stable,and antioxidative

A halogen‐free nitrogen‐rich additive was used to make polypropylene (PP) prepared for three different missions: fire retardancy, thermal stability, and antioxidative properties. The prepared additive was composed of a cyclodextrin, a nanohydroxyapatite, and a poly[[6‐[(1,1,3,3,‐tetramethylbutyl)amino]‐1,3,5‐triazine‐2,4‐diyl][(2,2,6,6‐tetramethyl‐4‐piperidinyl)imino]‐1,6‐hexanediyl[2,2,6,6‐tetramethyl‐4‐piperidinyl)imino] (SABO®STAB) integrated into a unique molecule, namely, BSDH. Fire retardancy performance of BSDH in PP was compared with that of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) commercially available additive in terms of cone calorimeter results. Thermal stabilities of PP/BSDH and PP/DOPO composites were compared by changes observed in pyrolysis activation energy values measured in thermogravimetric analysis under nitrogen atmosphere at various heating rates. Flame retardancy of PP/BSDH composite was reflected in a drop in the peak of Heat Release Rate by ca. 31% with respect to neat PP. Very interestingly, the results show that BSDH additive retarded thermal oxidation of PP macromolecular chains when compared with DOPO commercially available flame retardant, as signaled by a rise in oxidation induction time value as well as an increased early‐stage activation energy needed for thermal decomposition of PP in the presence of BSDH. J. VINYL ADDIT. TECHNOL., 25:366–376, 2019. © 2019 Society of Plastics Engineers     

Large eddy simulation of thermal stratification effect on convective and turbulent diffusion fluxes concerning gaseous pollutant dispersion around a high-rise model building

In this paper, the large eddy simulation (LES) approach is employed to investigate the role of different thermal stratification conditions (stable, neutral and unstable) in the air flow and gaseous pollutant dispersion processes around a high-rise non-isolated model building with 1:1:2 shape placed within a non-isothermal boundary layer. The simulation results are initially validated with available experimental measurements and then applied to study the characteristics of pollutant dispersion. Predictions show a low-velocity zone behind the model building. The major effect of a stable stratification on flow field is the formation of a weak recirculation flow in the wake region. Results represent an intense temperature gradient close to the sides of the model building for both stable and unstable conditions. Moreover, the convective and turbulent diffusion fluxes are compared under different thermal stratification conditions, and it is shown that the LES approach is capable of predicting the counter-gradient mechanism.     

Mass modeling of Bam orange with ANFIS and SPSS methods for using in machine vision

Orange is a citrus fruit which is rich in vitamins and minerals and other nutrients. Getting the relationship between physical properties of orange and its mass can create tremendous change in the packaging industry. The Iranian orange fruits used in this study consisted of Bam cultivars that they got from Kermanshah–Iran (longitude: 7.03°E; latitude: 4.22°N). One hundred samples were randomly selected. All the measurements were carried out at the laboratory with temperature of 24 °C during 2 days. Fourteen parameters were got by image processing for each orange. ANFIS and SPSS models were employed to predict the mass based on perimeter and (width/length) value as inputs. The coefficient of determination (R²) for ANFIS and SPSS were 0.936999 and 0.919 respectively. To evaluate the ANFIS model, samples were divided into two sets, 70% of data was used for training the model and 30% of data was used to test the model. So, The ANFIS model with less error percentage can be used to design and develop sizing systems.     

Use of a novel initiator for synthesis of amino-end functionalized polystyrene (NH2-PS) by atom transfer radical polymerization

Here we report a versatile new method for end-functionalizing polystyrene. In order to produce polystyrene with an amino end group, 2-(3-bromo-3-phenylpropyl)isoindoline-1,3-dione was synthesized and used as a novel initiator for ATRP. After ATRP polymerization, tri-n-butyltin hydride ((n-Bu)₃SnH) reductively replace existing halogens on polymer chains by hydrogen. Finally, the phthaloyl groups on polymer backbone were cleaved by treatment with hydrazine yielding amino terminated polystyrene. A polymer with M _n ≈ 10,350 and M _w/M _n = 1.17 was obtained. Therefore, this method allows the preparation of amino end functionalized polystyrene of narrow polydispersity with complete degree of functionalization.     

A study on the accuracy of force analogy method in nonlinear static analysis

In this paper, the accuracy of the force analogy method (FAM) for nonlinear static (pushover) analysis is investigated. Hence, after explanation of the concept of FAM by a new approach, 12 2D steel special moment resisting frames with different configurations were derived from two different 3D archetypes and modeled using four various methods of capturing nonlinearity including SAP2000 super elements, OpenSees force‐based and displacement‐based fiber method, and FAM. In addition, a MATLAB code was developed for modeling and analyzing the frames by FAM. The accuracy of FAM in predictions of pushover curves, base shear forces, and plastic rotation of the critical hinges was investigated. The results indicated that in general, the predictions obtained using the FAM had a good agreement and compatibility with those from other methods of analysis currently used in practice for seismic performance assessment of structures.     

Granular micromechanics model of anisotropic elasticity derived from Gibbs potential

This paper presents a Gibbs potential-based granular micromechanics approach capable of modelingmaterialswith complete anisotropy. The deformation energy of each grain–pair interaction is taken as a functionof the inter-granular forces. The overall classical Gibbs potential of a material point is then defined as thevolume average of the grain–pair deformation energy. As a first-order theory, the inter-granular forces arerelated to the Cauchy stress tensor using a modified static constraint that incorporates directional distributionof the grain–pair interactions. Further considering the conjugate relationship of the macroscale strain tensorand the Cauchy stress, a relationship between inter-granular displacement and the strain tensor is derived.To establish the constitutive relation, the inter-granular stiffness coefficients are introduced considering theconjugate relation of inter-granular displacement and forces. Notably, the inter-granular stiffness introducedin this manner is by definition different from that of the isolated grain–pair interactive. The integral formof the constitutive relation is then obtained by defining two directional density distribution functions; onerelated to the average grain–scale combined mechanical–geometrical properties and the other related to purelygeometrical properties. Finally, as the main contribution of this paper, the distribution density function isparameterized using spherical harmonics expansion with carefully selected terms that has the capability ofmodeling completely anisotropic (triclinic) materials. By systematic modification of this distribution function,different elastic symmetries ranging from isotropic to completely anisotropic (triclinic) materials are modeled.As a comparison, we discuss the results of the present method with those obtained using a kinematic assumptionfor the case of isotropy and transverse isotropy, wherein it is found that the velocity of surface quasi-shearwaves can show different trends for the two methods.