Elaboration of Al2O3/PTFE icephobic coatings for protecting aluminum surfaces

In order to protect aluminum ground wires and phase conductors of overhead power lines against ice adhesion and excessive accretion, for ensuring safe and reliable power transmission during winter periods, a new coating with icephobic characteristics and satisfactory mechanical properties was developed. The method consisted in depositing an extremely adherent poly(tetrafluoroethylene) or PTFE coating on an Al₂O₃ underlayer produced by anodisation in either a phosphoric or an oxalic acid electrolyte. PTFE impregnation was carried out at low temperature (320 °C) and coating adhesion was assessed using tape and bend tests. These treatments resulted in highly hydrophobic surfaces with water contact angles lying between 130° and 140°. Ice shear stress was reduced by almost 2.5 times, and the PTFE coatings remained active after several ice shedding events. Morphologies and chemical compositions were studied using scanning electron microscopy, energy dispersive X-Ray analysis, as well as Fourier Transform Infra Red and X-Ray photoelectron spectroscopy.     

Application of ion-engineered Persian Gulf seawater in EOR:effects of different ions on interfacial tension,contact angle,zeta potential,and oil recovery

In this study,we initially performed interfacial tension(IFT)tests to investigate the potential of using the Persian Gulf sea-water(PGSW)as smart water with dif...     

Wettability alteration and retention of mixed polymer-grafted silica nanoparticles onto oil-wet porous medium

Enhanced oil recovery(EOR)processes are applied to recover trapped or residual oil in the reservoir rocks after primary and secondary recovery methods.Changing ...     

FPGA based fast and high-throughput 2-slow retiming 128-bit AES encryption algorithm

This paper presents a high throughput digital design of the 128-bit Advanced Encryption Standard (AES) algorithm based on the 2-slow retiming technique on FPGA. The C-slow retiming is a well-known optimization and high performance technique. It can enhance designs with feedback loops and automatically rebalances the registers in the design. The C-slow retiming can break the critical path of the design into finer pieces to improve the throughput of the design. The complexity of the C-slow retiming on FPGA is to find the best register allocation in the data path of the design so that by increasing the number of registers, relocation of the registers to balance the AES architecture be in the best mode, and the critical path be optimally pipelined and improved. In this paper, architecture of the AES algorithm is implemented in the gate level by high-speed and breakable structures that are desirable for the 2-slow retiming. The Mix-columns transformation is implemented based on multiplication by constants 2 and 3 modules with combinational logic circuits. This work has been successfully verified and synthesized using Xilinx ISE 11 byVirtex-5, XC5VLX85 FPGA. The proposed implementation achieves a high throughput of 86 Gb/s and high maximum operation frequency of 671.524 MHz whereas the highest throughput and the highest operation frequency reported in the literature are 73.737 Gb/s and 576.07 MHz, respectively.     

pH- and thermo-sensitive MTX-loaded magnetic nanocomposites: synthesis,characterization, and in vitro studies on A549 lung cancer cell and MR imaging

In the current study, we proposed a facile method for fabrication of multifunctional pH- and thermo-sensitive magnetic nanocomposites (MNCs) as a theranostic agent for using in targeted drug delivery and magnetic resonance imaging (MRI). To this end, we decorated Fe₃O₄ magnetic nanoparticles (MNPs) with N,N-dimethylaminoethyl methacrylate (DMAEMA) and N-isopropylacrylamide (NIPAAm), best known for their pH- and thermo-sensitive properties, respectively. We also conjugated mesoporous silica nanoparticles (MSNs) to polymer matrix acting as drug container to enhance the drug encapsulation efficacy. Methotroxate (MTX) as a model drug was successfully loaded in MNCs (M-MNCs) via surface adsorption onto MSNs and electrostatic interaction between drug and carrier. The pH- and temperature-triggered release of MTX was concluded through the evaluation of in vitro release at both physiological and simulated tumor tissue conditions. Based on in vitro cytotoxicity assay results, M-MNCs significantly revealed higher antitumor activity compared to free MTX. In vitro MR susceptibility experiment showed that M-MNCs relatively possessed high transverse relaxivity (r₂) of about 0.15?mM^?1·ms^?1 and a linear relationship between the transverse relaxation rate (R₂) and the Fe concentration in the M-MNCs was also demonstrated. Therefore, the designed MNCs can potentially become smart drug carrier, while they also can be promising MRI negative contrast agent.     

A survey of decorative materials on the energy consumption of mid-rise residential buildings in Mashad, Iran

Polyvinylchloride (PVC) panel is one of the most favorite decorative materials that has been popularly applied as finishing of ceiling in residential buildings. It is about five years that the people incline to redecorate the ceiling of old buildings with PVC panel in big cities of Iran, such as Mashad. In this study, the influence of ceiling PVC panel on the cooling and heating loads of studied apartment were determined by software DeST-h. In addition, the summer natural ventilation of the mentioned apartment is investigated by determining the wind speed into the apartment through the computational fluid dynamics (CFD) software. The evaluation of environment indoor wind velocity showed that most of the apartment space is a comfortable zone. The results of studied building analyses demonstrated that using PVC panel on the ceiling can decline the energy consumption of the penthouse (fifth level) of the investigated building, which is about 3.7% and 7% for studied methods of without and with air layer, respectively. In addition, although the existence of air layer can decline the cooling and heating loads, the increase in air layer thickness did not show significant decrease on building energy consumption. However, the PVC panel is expensive and is not suitable to be used for ceiling thermal insulation, but adding a thin layer of air between ceiling and PVC panel can be a good step toward sustainable building, when the people are inclined to utilize it as a decorative ceiling.     

对轴压力作用下带有椭圆形开孔的圆柱形壳体屈曲的数值和试验研究

在圆柱形壳体的设计中,开孔对于其承载能力及屈曲性能的影响非常大。采用有限元方法对具有不同尺寸开孔的薄壁钢圆柱形壳进行模拟和分析,分析了开孔的位置、长度与直径比值（L／D）和直径与厚度比值（D／t）对圆柱形壳届曲和后屈曲性能的影响。采用INSTRON 8802液压系统对一些构件进行屈曲试验,并将试验结果与数值计算结果进行对比发现,两者具有非常好的一致性。最后,基于试验和数值分析结果,提出计算这类结构屈曲荷载的公式。     

Optimal control of steel structures by improved particle swarm

Active control is one of the modern approaches in seismic design of steel structures. Recently, induced by economic considerations, especially high expenses of control systems, optimality has become an important issue. In this paper an active system is used to control a steel structure’s displacements by a simplified pole assignment method. To optimize the number, the locations, and the total driving force of the required actuators, an improved particle swarm algorithm is presented focusing on the parameters of the velocity equation. A Geographical neighborhood topology and an adaptive inertia weight are used to improve the standard PSO algorithm. In addition to the local and global best solutions, the positions of the best particles in the geographical neighborhood are mathematically represented in an additional term. The performance of the proposed algorithm is compared with the traditional Genetic Algorithm (GA) and the standard particle swarm considering the optimal control of a 12-story steel structure as a numerical example. High capabilities of the proposed method in terms of the control target, convergence rate, and accuracy are simultaneously clarified by the results.     

Predicting the existence of stormwater first flush from the time of concentration

Simulations were performed using a one-dimensional kinematic wave model to examine the relationships between the time of concentration (T(c)) and the first flush (FF) for impervious landuses. The model used chemical oxygen demand parameters from a highway runoff site in west Los Angeles for eight storm events. FF indices such as the mass first flush ratio (MFF(n)) and the partial event mean concentration to event mean concentration ratio (PEMC(t)/EMC) were calculated from simulations using various rainfall intensities, rainfall durations, bed slopes, and watershed lengths (L), and matched measured values with an RMS error of 25% for six events. Resulting values of MFF(20) and PEMC(60)/EMC were correlated to T(c) calculated using ASCE's kinematic wave formula, and showed a non-monotone relationship, with very short or long T(c) having low MFF(20) with a maximum for mid-range T(c). Contours of the MFF(20) and PEMC(60)/EMC were created to predict and quantify FF from known T(c), L, and rainfall duration (T).