Cr(VI) Immobilization Process in a Cr‐Spiked Soil by Zerovalent Iron Nanoparticles: Optimization Using Response Surface Methodology

The response surface methodology involving the five‐level central composite design (CCD) was employed to model and optimize the Cr(VI) immobilization process in a Cr‐spiked soil using starch‐stabilized zerovalent iron nanoparticles (ZVIn). ZVIn were synthesized via a borohydride reduction method and characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). All Cr(VI) immobilization experiments were conducted in a batch system. The variables for the CCD optimization were the ZVIn dosage (% w/w), reaction time (min), and initial Cr(VI) concentration in soil (mg/kg). The predicted response values by the second‐order polynomial model were found to be in good agreement with experimental values (R² = 0.968 and adj‐R² = 0.940). The optimization result showed that the Cr(VI) immobilization efficiency presented the maximal result (90.63%) at the following optimal conditions: ZVIn dosage of 1.5% w/w, reaction time of 60 min, and an initial Cr(VI) concentration of 400 mg/kg.     

Warm generalized cosmic Chaplygin gas inflation inspired by generalized dissipative coefficient

We examine the warm inflationary universe model in the presence of generalized cosmic Chaplygin gas and standard scalar field. We assume the generalized dissipative coefficient and corresponding weak and strong dissipative regimes. In this framework, we analyze the characteristics of inflationary dynamics under the slow-roll approximations. Under these approximations, we formulate the important inflationary parameters, such as scalar spectral index, scalar and tensor power spectrum, tensor-to-scalar ratio etc. It is interesting to note that our results for these inflationary parameters are well corroborated with the recent observational data like WMAP7, WMAP9 and Planck data.     

塔克拉玛干沙漠塔中与巴丹吉林沙漠拐子湖地表辐射特征对比

利用塔克拉玛干沙漠腹地塔中和巴丹吉林沙漠北缘拐子湖两个陆气通量监测站2013年2月-2014年1月地面辐射观测数据及相应气象资料,对比分析塔中和拐子湖两地的太阳辐射通量和地表反照率差异特征,同时也探究了两地太阳辐射通量和地表反照率与太阳高度角之间的关系。结果表明：（1）塔中和拐子湖两地各辐射通量均呈较为同步的季节变化特征;具有太阳辐射优势的塔中地区因沙尘天气的影响在部分月份地表总辐射小于拐子湖地区;拐子湖由于地表沙粒相对较粗且包含大量透明度较高的石英颗粒,地表反照率和反射辐射均大于塔中地区;两地各辐射通量月平均日变化均呈现出标准倒"U"型结构;（2）拐子湖较粗的地表沙粒导致沙尘天气过后不易形成浮尘,沙尘天气过后各辐射通量恢复至发生之前的状态较塔中地区迅速;（3）两地太阳高度角夏季最大,冬季最小,最大值均可达75°左右,最小值塔中和拐子湖地区分别为45°和40°;各辐射通量随着太阳高度角的升高而增加,地表反照率随之减小,但受多种因素影响各辐射通量最大值并未出现在太阳高度角最大的时候。     

Determination of sediment deposition of Hasanlar Dam using bathymetric and remote sensing studies

Natural Hazards - Hasanlar Dam and Hydroelectric Power Plant are located on Küçük Melen Creek in the Western Black Sea Basin of Turkey. The dam was constructed in 1974 to provide...     

On the importance of boundary layer calculations instead of viscous correction in heavily loaded marine propellers while using a surface panel method

A surface panel method is employed for the thin boundary layer calculation of heavily loaded marine propellers in steady state conditions. Employing the surface panel method, known as the “Morino Method”, the flow field around the propeller is represented by an unknown potential. The majority of the flow field is governed by the potential theory while the viscosity is assumed to be largely confined to thin shear layer on the propeller surface. The boundary layer calculations are performed by using Cebeci-Smith two dimensional model and the local skin friction coefficients and blowing velocities are obtained along the pre-computed on-body streamlines. It is shown that the prediction of torque of the propeller is improved when the boundary layer calculations are used instead of the boundary layer corrections based on the formulae established for the flat plates.     

Hydrological mapping from SPOT imagery

Four SPOT images, one panchromatic and three multispectral, were studied to evaluate their usefulness for hydrological mapping in an arid environment. Simple visual methods of interpretation were used to plot the drainage network independently from each test image. The results were compared with the drainage network shown on the topographic map of the area. Results show that with the panchromatic image, over 90 per cent of the map content could be discerned, identified, and plotted. The accuracy of plotting the drainage system from the multispectral images seems to depend on the season in which data had been acquired. However, in all cases, the success rate is not less than 70 per cent. Comparison with Landsat Thematic Mapper (TM) imagery showed that SPOT system is superior in hydrological mapping.     

Analytical solutions for one-dimensional advection–dispersion equation of the pollutant concentration

We present simple analytical solutions for the unsteady advection–dispersion equations describing the pollutant concentration C(x, t) in one dimension. The solutions are obtained by using Laplace transformation technique. In this study we divided the river into two regions x ≤ 0 and x≥0 and the origin at x = 0. The variation of C(x, t) with the time t from t = 0 up to t → ∞ (the steady state case) is taken into account in our study. The special case for which the dispersion coefficient D = 0 is studied in detail. The parameters controlling the pollutant concentration along the river are determined.     

Object-based classification of hyperspectral data using Random Forest algorithm

This paper presents a new framework for object-based classification of high-resolution hyperspectral data. This multi-step framework is based on multi-resolution segmentation (MRS) and Random Forest classifier (RFC) algorithms. The first step is to determine of weights of the input features while using the object-based approach with MRS to processing such images. Given the high number of input features, an automatic method is needed for estimation of this parameter. Moreover, we used the Variable Importance (VI), one of the outputs of the RFC, to determine the importance of each image band. Then, based on this parameter and other required parameters, the image is segmented into some homogenous regions. Finally, the RFC is carried out based on the characteristics of segments for converting them into meaningful objects. The proposed method, as well as, the conventional pixel-based RFC and Support Vector Machine (SVM) method was applied to three different hyperspectral data-sets with various spectral and spatial characteristics. These data were acquired by the HyMap, the Airborne Prism Experiment (APEX), and the Compact Airborne Spectrographic Imager (CASI) hyperspectral sensors. The experimental results show that the proposed method is more consistent for land cover mapping in various areas. The overall classification accuracy (OA), obtained by the proposed method was 95.48, 86.57, and 84.29% for the HyMap, the APEX, and the CASI data-sets, respectively. Moreover, this method showed better efficiency in comparison to the spectral-based classifications because the OAs of the proposed method was 5.67 and 3.75% higher than the conventional RFC and SVM classifiers, respectively.     

Arbitrary amplitude ion-acoustic solitary waves in superthermal electron-positron-ion magnetoplasma

Arbitrary amplitude ion-acoustic solitary waves propagating in a magnetized plasma composed of positive ions, superthermal electrons and positrons are investigated. For this purpose, the ions are represented by the hydrodynamical fluid equations while the non-Maxwellian electrons and positrons densities are assumed to follow kappa (κ) distribution. The basic equations are reduced to a pseudoenergy-balance equation. Existence conditions for large amplitude solitary waves are presented. The analytical and numerical analysis of the latter show that the ion-acoustic solitary wave can propagate only in the subsonic region in our plasma system and it is significantly influenced by the plasma parameters. The present analysis could be helpful for understanding the nonlinear ion-acoustic solitary waves propagating in interstellar medium and pulsar wind, which contain an excess of superthermal particles.