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151.

Prediction of pile-bearing capacity developing artificial intelligence models has been done over the last decade. Such predictive tools can assist geotechnical engineers to easily determine the ultimate pile bearing capacity instead of conducting any difficult field tests. The main aim of this study is to predict the bearing capacity of pile developing several smart models, i.e., neuro-genetic, neuro-imperialism, genetic programing (GP) and artificial neural network (ANN). For this purpose, a number of concrete pile characteristics and its dynamic load test specifications were investigated to select pile cross-sectional area, pile length, pile set, hammer weight and drop height as five input variables which have the most impacts on pile bearing capacity as the single output variable. It should be noted that all the aforementioned parameters were measured by conducting a series of pile driving analyzer tests on precast concrete piles located in Pekanbaru, Indonesia. The recorded data were used to establish a database of 50 test cases. With regard to data modelling, many smart models of neuro-genetic, neuro-imperialism, GP and ANN were developed and then evaluated based on the three most common statistical indices, i.e., root mean squared error (RMSE), coefficient determination (R2) and variance account for (VAF). Based on the simulation results and the computed indices’ values, it is observed that the proposed GP model with training and test RMSE values of 0.041 and 0.040, respectively, performs noticeably better than the proposed neuro-genetic model with RMSE values of 0.042 and 0.040, neuro-imperialism model with RMSE values of 0.045 and 0.059, and ANN model with RMSE values of 0.116 and 0.108 for training and test sets, respectively. Therefore, this GP-based model can provide a new applicable equation to effectively predict the ultimate pile bearing capacity.

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152.
    
In Malaysia, oil palm shell (OPS) is an agricultural solid waste originating from the palm oil industry. In this investigation old OPS was used for production of high strength lightweight concrete (HSLC). The density, air content, workability, cube compressive strength and water absorption were measured. The effect of five types of curing conditions on 28-day compressive strength was studied. The test results showed that by incorporating limestone powder and without it, it is possible to produce the OPS concretes with 28-day compressive strength of about 43–48 MPa and dry density of about 1870–1990 kg/m3. The compressive strength of OPS HSLC is sensitive to the lack of curing. The water absorption of these concretes is in the range of good concretes.  相似文献   
153.
    
The main objective of this work was to prepare a tailor‐made electrospun nanofibrous samples based on poly(?‐caprolactone) (PCL) containing tetracycline hydrochloride (TC‐HCl) as a middle layer and poly(vinyl alcohol) (PVA) including phenytoin sodium (PHT‐Na) as lateral layers. The characterizations of the three‐layered electrospun samples were carried out by using SEM, ATR‐FTIR spectroscopy along with swelling/weight loss, UV–vis spectrophotometry as well as HPLC, antibacterial and MTT tests. The SEM micrograph images showed that the average diameter of PCL nanofibers was decreased from 243 ± 7 nm to 181 ± 5 nm by adding TC‐HCl. The hydrolytic degradation of PVA nanofibers in the exposure of phosphate buffer solution (PBS) was confirmed by ATR‐FTIR results in which a change at the intensity of the characteristic peak located at 3333 cm?1 corresponding to hydroxyl groups (? OH) was observed. The UV–vis outcomes revealed a sustained control release of TC‐HCl from the three‐layered nanofibrous samples (PVA/PCL/PVA) with an amount of about 43% compared to the PCL nanofibers which had an ultimate release of the drug about 79%. Furthermore, the HPLC chromatograms showed the released PHT‐Na from PVA nanofibers about 87%. Finally, the MTT assay along with the antibacterial evaluation exhibited that the surfaces of these electrospun three‐layered nanofibrous samples have no cytotoxicity as well as the controlled release of TC‐HCl from them enabled their prolonged use for preventing the bacterium growth such as S. aureus during 24‐h treatment time. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43309.  相似文献   
154.
    
In this article, we present the drug‐release rate, water uptake, water permeability, morphology, and mechanical properties of a series of active wound dressing nanofibrous mats prepared via an electrospinning process of poly(lactic acid) (PLA), poly(?‐caprolactone) (PCL), and their (50/50) blends loaded with different doses of tetracycline hydrochloride antibiotic. The performance of these active wound dressings in terms of a sustained and suitable drug‐release rate, adequate water uptake and water permeability, and antibacterial activities were compared with those of a commercial wound dressing (Comfeel Plus). The results show that the dressings made from PCL and PLA/PCL blends showed better performance compared with the commercial wound dressing sample as far as these properties were concerned. The improved performance could be explained on the basis of the nanofibrous structure of the mats and the hydrophilicity of PCL and PLA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   
155.
    
In this work, a new elastomeric liner was introduced to protect the metal surfaces of storage tanks against corroding materials in petrochemical industries. This new liner was prepared on the basis of EPDM/NR and EPDM/SBR compounds. The elastomeric compounds were cured by using super‐heated water vapor at atmospheric pressure. To increase the rate of curing in these rubber samples, the optimum curing system contained 15 phr sulfur and 1.5 phr mercaptobenzothiazole, 1.5 phr zinc diethyl dithiocarbamate, and 1.8 phr tetramethylthiuram disulfide accelerators. Mechanical tests showed that ultimate tensile strength, elongation at break, and hardness of both polyblend samples were comparable to the SBR/NR blend, which is widely used in the rubber lining of metallic surfaces. In the next step, the chemical resistance of the samples was measured by placing them in a 30 wt % HCl solution. The tensile strength, elongation at break, and weight loss of the samples were measured before and after immersion in HCl. Also, the chemical resistances for EPDM/NR, EPDM/SBR, and SBR/NR samples were qualitatively measured in caustic solution. The cracking, blistering, permeability, and adhesion of the rubber samples to steel surface were observed. Finally, the results showed that EPDM/SBR (70/30) polyblend can be a suitable substitute for conventionally used SBR/NR (50/50) for a successful rubber used to line metallic surfaces. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   
156.
Wireless Personal Communications - A new design of a 1:2 and 1:4 microstrip power divider is proposed using finite defected ground structure (FDGS), in this paper. In order to design the presented...  相似文献   
157.

The type of materials used in designing and constructing structures significantly affects the way the structures behave. The performance of concrete and steel, which are used as a composite in columns, has a considerable effect upon the structure behavior under different loading conditions. In this paper, several advanced methods were applied and developed to predict the bearing capacity of the concrete-filled steel tube (CFST) columns in two phases of prediction and optimization. In the prediction phase, bearing capacity values of CFST columns were estimated through developing gene expression programming (GEP)-based tree equation; then, the results were compared with the results obtained from a hybrid model of artificial neural network (ANN) and particle swarm optimization (PSO). In the modeling process, the outer diameter, concrete compressive strength, tensile yield stress of the steel column, thickness of steel cover, and the length of the samples were considered as the model inputs. After a series of analyses, the best predictive models were selected based on the coefficient of determination (R2) results. R2 values of 0.928 and 0.939 for training and testing datasets of the selected GEP-based tree equation, respectively, demonstrated that GEP was able to provide higher performance capacity compared to PSO–ANN model with R2 values of 0.910 and 0.904 and ANN with R2 values of 0.895 and 0.881. In the optimization phase, whale optimization algorithm (WOA), which has not yet been applied in structural engineering, was selected and developed to maximize the results of the bearing capacity. Based on the obtained results, WOA, by increasing bearing capacity to 23436.63 kN, was able to maximize significantly the bearing capacity of CFST columns.

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158.

Background  

A newly designed electrostatic precipitator (ESP) in tandem with Versatile Aerosol Concentration Enrichment System (VACES) was developed by the University of Southern California to collect ambient aerosols on substrates appropriate for chemical and toxicological analysis. The laboratory evaluation of this sampler is described in a previous paper. The main objective of this study was to evaluate the performance of the new VACES-ESP system in the field by comparing the chemical characteristics of the PM collected in the ESP to those of reference samplers operating in parallel.  相似文献   
159.
160.
    
This paper presents a systematic method to decompose uncertain linear quantum input‐output networks into uncertain and nominal subnetworks, when uncertainties are defined in SLH representation. To this aim, two decomposition theorems are stated, which show how an uncertain quantum network can be decomposed into nominal and uncertain subnetworks in cascaded connection and how uncertainties can be translated from SLH parameters into state‐space parameters. As a potential application of the proposed decomposition scheme, robust stability analysis of uncertain quantum networks is briefly introduced. The proposed uncertainty decomposition theorems take account of uncertainties in all three parameters of a quantum network and bridge the gap between SLH modeling and state‐space robust analysis theory for linear quantum networks.  相似文献   
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