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1.
In this study, Adaptive Neuro-Fuzzy Inference System (ANFIS) has been used to model local scouring depth and pattern scouring around concave and convex arch shaped circular bed sills. The experimental part of this research study includes seven sets of laboratory test cases which were performed in an experimental flume under different flow conditions. A data set consists of 2754 data points of scouring depth were collected to use in the ANFIS model. The ratio of arch diameter, D, to flume width, W, is used as a non dimensional variables in all test cases. The results from ANFIS model were compared with the results of ANN model obtained by Homayoon et al. [24] and previously presented models. The results indicated that for D/W equal to 1 and 1.2, the ANFIS models produced a good performance for convex and concave bed sills. As a result, the ANFIS models can be used as an alternative to ANN for estimation of scour depth and scour pattern around a concave bed sill installed with a bridge pier. 相似文献
2.
Thermal,mechanical, and barrier properties of polyethylene/surlyn/organoclay nanocomposites blown films prepared by different mixing methods
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Homayoon Hosseinkhanli Jamal Aalaie Mahdi Abdollahi Talat Khalkhali Mehrdad Shojaei 《乙烯基与添加剂工艺杂志》2015,21(1):60-69
(Low‐density polyethylene) (LDPE)/clay nanocomposites were prepared by melt blending in a twin‐screw extruder by using different mixing methods. Zinc‐neutralized carboxylate ionomer was used as a compatibilizer. Blown films of the nanocomposites were then prepared. The effect of mixing method on the clay dispersion and properties of the nanocomposites was evaluated by wide‐angle X‐ray diffraction analysis, mechanical properties, thermal properties, and barrier properties. The structure and properties of nanocomposites containing different amounts of nanoclay prepared by selected mixing techniques were also investigated. It was found that melt compounding of Surlyn/clay masterbatch with pure LDPE and Surlyn (two‐step‐a method) results in better dispersion and intercalation of the nanofillers than melt mixing of LDPE/Surlyn/clay masterbatch with pure LDPE and surlyn (two‐step‐b method) and direct mixing of LDPE with clay. The films containing ionomer have good barrier properties. A wide‐angle X‐ray diffraction pattern indicates that intercalation of polymer chains into the clay galleries decreases by increasing the clay content. Barrier properties and tensile modulus of the films were improved by increasing the clay content. In addition, tensile strength increased in the machine direction, but it decreased in the transverse direction by increasing the clay content. DSC results showed that increasing the clay content does not show significant change in the melting and crystallization temperatures. The results of thermogravimetric analysis showed that the thermal stability of the nanocomposites decreased by increasing the clay content more than 1 wt%. J. VINYL ADDIT. TECHNOL., 21:60–69, 2015. © 2014 Society of Plastics Engineers 相似文献
3.
A key factor in the transition of the existing network to an intelligent network (IN) environment is the need to partition the network intelligence and to ensure the coexistence of the embedded switch services with the externally controlled services. If the network intelligence can be defined by entities (e.g. access control and routing, connection control, basic call control, feature control, etc.), then the issue is how to manage their distribution over the evolving network elements (NEs). The authors focus on the early phases of the IN, during a 1991-2 time frame, when these features must interwork with the existing features (e.g. those within the Centrex service). They provide an overview of the features interactions and arbitration policies prevailing in today's network. They then describe the framework for both single- and multinode networked features models. The issues of call control distributed over the NEs of the IN are treated as extensions to the concepts and interfaces needed to provide networked services like areawide Centrex and private virtual networks. A model for offering IN/1+ services is described 相似文献
4.
Asghari Abbas Azadi-Tinat Nima Oraizi Homayoon Ghalibafan Javad 《Wireless Personal Communications》2019,108(3):1529-1546
Wireless Personal Communications - One of the important objectives of underwater acoustic sensor network is to extend the lifespan of a network which depends on the topology control mechanisms.... 相似文献
5.
Alireza Sharif Jamal Aalaie Homeira Shariatpanahi Homayoon Hosseinkhanli Alireza Khoshniyat 《Journal of Polymer Research》2011,18(6):1955-1969
The effects of nanoclay on the structure and final properties of high density polyethylene (HDPE)/thermoplastic starch (TPS)
blends were investigated. Neat blends as well as nanoclay containing samples were prepared by melt blending in an internal
mixer. Also, a poly (ethylene-g-maleic anhydride) (PE-g-MA) copolymer was used as compatibilizer in some of the formulations.
Nanocomposites with intercalated structures were obtained in the samples lacking the compatibilizer, based on the rheological,
X-ray diffraction (XRD) and transmission electron microscopy (TEM) results. However, some of the silicate layers were nearly
exfoliated in the presence of the compatibilizer. The nanoclay was located preferably in the HDPE matrix as well as at the
interface of the HDPE matrix and TPS dispersed phase. The ability of the nanoclays in decreasing the average size of TPS phase
in the HDPE matrix was confirmed by scanning electron microscopy (SEM) observations. Furthermore, thermo-gravimetric analysis
(TGA) showed that the nanoclays could enhance the thermal stability of the samples. It seems that nanoclays performed as an
insulator and mass transport barrier to the small molecules generated during decomposition, and assisted in the formation
of char after thermal decomposition of the polymer matrix. All the samples containing the compatibilizer possessed higher
tensile strength and elongation at break, but lower modulus, compared to the corresponding un-compatibilized samples. Finally,
incorporation of the nanoclays was found to be in favor of developing nanocomposites with higher biodegradability as evidenced
through a biodegradation test by fungi as well as water uptake experiments. 相似文献
6.
Homayoon Hosseinkhanli Alireza Sharif Jamal Aalaie Talat Khalkhali Shahin Akhlaghi 《乙烯基与添加剂工艺杂志》2013,19(2):132-139
Various (low‐density polyethylene)/poly(ethylene‐co‐vinyl acetate) (LDPE/EVA) nanocomposites containing organoclay were prepared by one‐ and two‐step procedures through melt blending. The resultant nanocomposites were then processed via the film blowing method. From the morphological point of view, X‐ray diffraction and optical microscopy studies revealed that although a prevalent intercalated morphology was evident in the absence of EVA, a remarkable increase of organoclay interlayer spacing occurred in the EVA‐containing systems. The advantages of the addition of EVA to the LDPE/organoclay nanocomposites were confirmed in terms of oxygen barrier properties. In other words, the oxygen transmission rates of the LDPE/EVA/organoclay systems were significantly lower than that of the LDPE/organoclay sample. The LDPE/EVA/organoclay films had better mechanical properties than their counterparts lacking the EVA, a result which could be attributed to the improvement of the organoclay reinforcement efficiency in the presence of EVA. Differential scanning calorimetry and thermogravimetric analysis experiments were performed to follow the effects of the EVA and/or organoclay on the thermal properties of LDPE. Finally, the films produced from the two‐step‐procedure compound showed enhanced oxygen barrier properties and mechanical behavior as compared to the properties of the films produced via the one‐step procedure. J. VINYL ADDIT. TECHNOL., 19:132–139, 2013. © 2013 Society of Plastics Engineers 相似文献
7.
AbstractMembrane technologies as conservative approaches have absorbed much attention in chemical and petroleum engineering, recently. The current research presents the preparation of effectively mixed matrix membranes (MMMs) using polyether-block-amide (Pebax-1657) as a polymeric matrix and zinc oxide (ZnO) nanoparticles with various contents (0.0, 2.5, 5.0, 7.5, and 10.0?wt%) as a filler. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and field emission scanning microscopy (FESEM) were conducted to characterize the prepared membranes. The membrane performance was evaluated by caring out permeation experiments of the CO2 and CH4 at a pressure of 3?bar and temperature of 30?°C. Based on the obtained results, the CO2 permeability and ideal CO2/CH4 selectivity increased about 13 and 21%, respectively at 10.0?wt% loading of ZnO in the polymer matrix. 相似文献
8.
Based on the algebraic correspondence between the displacement equations of the plane, spherical and skew four-bar linkages and the plane and skew slider-crank mechanisms, a highly compact, computationally efficient procedure has been developed for a microcomputer kinetmatic analysis of these linkages. 相似文献
9.
Miniaturization and dual‐banding of an elevated slotted patch antenna using the novel dual‐reverse‐arrow fractal
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A novel fractal geometry called dual‐reverse‐arrow fractal (DRAF) is introduced and compared with various versions of Koch fractals for application to triangular patch antennas. It is shown that DRAF results in the reduction of antenna size and tends to maintain its bandwidth. The presented DRAF is applied for the reduction of size of an elevated triangular patch antenna for the dual band operation in WLAN. This DRAF antenna has achieved 40% size reduction compared to a simple triangular patch antenna. For the provision of required bandwidth in the second frequency band (4.9‐5.9 GHz), a stepped U‐shaped slot is cut in the triangular patch. This antenna is more compact than similar antennas reported in the literature but maintains its fractional bandwidth (%25). The optimized design of the proposed DRAF antenna with air gap and slot is fabricated and tested, which verifies its expected specifications. 相似文献
10.
The effect of silica fume on deterioration resistance to sulfate attack in seawater within tidal zone and simulated wetting-drying condition has been studied in Portland cement concretes and pastes containing silica fume (SF) with/without ground granulated blast furnace slag (GGBS). Changes in the compressive strength and capillary water absorption of specimens as a function of SF content have been investigated combined with phases determination by means of scanning electron microscopy and X-ray energy dispersion analysis. The strength change factors (SCFs) of specimens with SF (the more SF content, the higher strength loss) were greater than that of the mixes without SF or cured under tap water. Mg2+ ion originated attack found to be the dominating deterioration mechanism as confirmed by X-ray and chemical analyses.Further, the incorporation of GGBS with SF mixes in different exposure conditions led to the worst performance in all of the test environments. Lower cement content and hydration rate accompanied with particular chemical composition of GGBS made concrete and paste specimens to be more susceptible to deleterious seawater environment. 相似文献