Sensitive Ion‐Flotation Separation of Ag(I) Traces Using 2‐(2‐Methoxyphenyl)benzimidazole before Flame Atomic Absorption Spectrometric Determination in Water

A sensitive, reliable, and environmentally friendly method for simple separation and preconcentration of Ag(I) traces in aqueous samples is presented prior to their flame atomic absorption spectrometric determinations. At pH 7.0, Ag(I) was separated with 2‐(2‐methoxyphenyl)benzimidazole (MPBI) as a new complexing agent and floated after adding sodium dodecyl sulfate (SDS) as a foaming reagent. The floated layer was then dissolved in proper amount of concentrated nitric acid in methanol and introduced to the flame atomic absorption spectrometer (FAAS). The effects of pH, concentration of MPBI, type and amount of surfactant as the floating agent, type and amount of eluting agent, and influence of foreign ions on the recovery of the analyte ion were investigated. Also, using a nonlinear curve fitting method, the formation constant of 1.62 × 10⁶ was obtained for Ag(I)–MPBI complex. The analytical curve was linear in the range of 1.8 × 10^?7–1.7 × 10^?6 mol/L for determination of Ag(I). The relative standard deviation (RSD; N = 10) corresponding to 0.7 × 10^?6 mol/L of Ag(I), the limit of detection (10 blanks), and the enrichment factor were obtained as 1.7%, 2.9 × 10^?8 mol/L, and 43.0, respectively. The proposed procedure was then applied successfully for determination of silver ions in different water samples.     

Deflection amplification factor for estimating seismic lateral deformations of RC frames

Different values have been assigned to the ratio of the defl ection amplifi cation factor(Cd) to the response modifi cation factor(R) for a specifi ed force-resisting system in the seismic design provisions while the same application is defi ned for it. An analytical study of the seismic responses of several reinforced concrete frames subjected to a suite of earthquake records performed in this research indicate that the stories’ overstrength and stiffness distribution along the structural height can affect local defl ections more than global ones. Therefore, the Cd/R ratio is calculated based on the ratio of both maximum inelastic to maximum elastic displacements and interstory drifts. Due to damage concentration in some specifi c stories, the defl ection amplifi cation factor calculated based on inelastic interstory drifts was larger than that of the inelastic displacements. Consequently, a minimum value of 1.0 is recommended for the Cd/R ratio in order to estimate maximum inelastic drifts. The ratio of inelastic to elastic displacement was generally found to increase slightly along the structural height for the studied RC models. In addition, it was detected that the story damage indices of the studied RC frames decrease when the inverted value of inelastic interstory drift ratios are increased through a(negative) power form.     

A methodology to determine thermal conductivity of soils from flux measurement

Determination of thermal properties of soils (viz., thermal resistivity, thermal conductivity, thermal diffusivity and heat capacity), which primarily influence heat migration through the soil mass, is essential in situations where geomaterials are relentlessly subjected to higher temperatures and temperature variations. These properties of the soil mainly depend upon its type, mineralogy, particle size and gradational characteristics, density and water content. In this context, earlier researchers have determined thermal conductivity of soils by employing a thermal probe (a line heat source), which works on the principle of transient method (TM) of heat conduction. However, this methodology cannot be employed for establishing the heat flow (read thermal regime) through the soil. Hence, development of an alternate technique, which facilitates quantification of temporal and spatial variation of the heat flux and temperature in the soil mass, becomes essential. With this in mind, a methodology to determine thermal conductivity of soils by employing the concept of thermal flux measurement (TFM) has been developed and its details are presented in this paper. Results obtained from the TM and TFM have also been critically evaluated for the sake of validation and generating more confidence in the proposed methodology.     

Determination of sand dune characteristics through geomorphometry and wind data analysis in central Iran (Kashan Erg)

The combination of wind measurements and remotely sensed geomorphometry indices provides a valuable resource in the study of desert landforms, because arduous desert environments are difficult to access. In this research, we couple wind data and geomorphometry to separate and classify different sand dunes in Kashan Erg in central Iran. Additionally, the effect of sand-fixing projects on sand dune morphology was assessed using geomorphometry indices (roughness, curvature, surface area, dune spacing and dune height). Results showed that a Digital Elevation Model of the National Cartographic Center of Iran (NCC DEM) with 10-m resolution and accuracy of 54% could discriminate geomorphometry parameters better than the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data with 30-m resolution and Shuttle Radar Topography Mission (SRTM) data with 90-m resolution and 45.2 and 1.6% accuracy, respectively. Low classification of SRTM DEM was associated with too many non-value points found in the DEM. Accuracy assessment of comparison ground control points revealed that ASTER DEM (RMSE = 4.25) has higher accuracy than SRTM and NCC DEMs in this region. Study of curvature showed that transverse and linear sand dunes were formed in concave topography rather than convex. Reduced slopes in fixed sand dunes were established due to wind erosion control projects. Measurements of dune height and spacing show that there is significant correlation in compound dunes (R ² = 0.546), linear dunes (R ² = 0.228) and fixed dunes (R ² = 0.129). In general, the height of dunes in Kashan Erg increases from the margin of the field to the center of the field with a maximum height of 120 m in star dunes. Analysis of wind data showed that sand drift potential is in low-medium class in Kashan Erg. Linear sand dunes in Kashan Erg show that they are following a global trend in forming of these. Finally, established of geomorphometry method in dune classification will help researchers to identify priority of land management and performance assessment of sand dunes fixing projects in arid arduous environment.     

Tree failure prediction model (TFPM): machine learning techniques comparison in failure hazard assessment of Platanus orientalis in urban forestry

Natural Hazards - Trees are generally harmed by multitude factors consisting of ecological condition and anthropogenic pressures in the cities. This study compares the multilayer perceptron (MLP)...     

Facies Analysis, Sequence Stratigraphy and Diagenetic Studies of the Jurassic Carbonates of the Kohat Basin, Northwest Pakistan: Reservoir Implications

The present study deals with the depositional facies, diagenetic processes and sequence stratigraphy of the shallow marine carbonates of the Samana Suk Formation, Kohat Basin, in order to elucidate its reservoir quality. The Samana Suk Formation consists of thin to thick-bedded, oolitic, bioclastic, dolomitic and fractured limestone. Based on the integration of outcrop, petrographic and biofacies analyses, the unit is thought to have been deposited on a gentle homoclinal ramp in peritidal, lagoonal and carbonate shoal settings. Frequent variations in microfacies based sea-level curve have revealed seven Transgressive Systems Tracts (TSTs) and six Regressive Systems Tracts (RSTs). The unit has undergone various stages of diagenetic processes, including mechanical and chemical compaction, cementation, micritization, dissolution and dolomitization. The petrographic analyses show the evolution of porosity in various depositional and diagenetic phases. The fenestral porosity was mainly developed in peritidal carbonates during deposition, while the burial dissolution and diagenetic dolomitization have greatly enhanced the reservoir potential of the rock unit, as is further confirmed by the plug porosity and permeability analyses. The porosities and permeabilities were higher in shoal facies deposited in TSTs, as compared to lagoonal and peritidal facies, except for the dolomite in mudstone, deposited during RSTs. Hence good, moderate and poor reservoir potential is suggested for shoal, lagoonal and peritidal facies, respectively.     

A one-dimensional Explicit Time-dependent cloud Model (ETM): Description and validation with a three-dimensional cloud resolving model

An algorithm for a one-dimensional Explicit Time-dependent cloud Model (ETM) that takes into account non-hydrostatic pressure, entrainment, cloud microphysics, lateral and vertical eddy mixing processes is developed and tested against a state-of-the-art cloud resolving three dimensional mesoscale model—the Advanced Regional Prediction System (ARPS). The numerical schemes and sub-grid scale processes are rather similar in both ETM and ARPS, although the dimensionality is different.Results show that the ETM is able to simulate the complete lifecycle for a cloud cell, featuring comparable zones of maximum vertical velocity, and overshooting layers on the cloud top. Heat and moisture fluxes within the cloud column of the ETM occur at the same level as ARPS, giving confidence towards adequate formulations in ETM. However, mass flux fields are not in good agreement; there is significant difference in intensity and the altitude where maxima occur. Sensitivity of the ARPS cloud to the amplitude and depth of the initial thermal bubble was examined; the resulting cloud showed sensitivity to both parameters. The maximum vertical velocity decreases with greater amplitude and occurs earlier. This was used as a tuning parameter to ensure similarity in the lifecycle of ETM and ARPS clouds.     

Anomaly Detection from Hyperspectral Images Using Clustering Based Feature Reduction

An anomaly detection method with a clustering based feature reduction is proposed in this paper to improve the performance of the Local RX detector. Because of high dimensionality of hyperspectral image and the low number of available samples in each local region around each testing pixel, the estimate of local covariance matrix is not possible. So, because of singularity problem, Local RX cannot use the local covariance matrix and misses the local structures of data to model the background clutter. To deal with this problem, a supervised clustering based feature reduction is introduced for extraction of background features with minimum overlap and redundant information. In the projected feature space with reduced dimensionality, the local structures of background pixels are estimated to efficiently model the background data. The experiments done on both synthetic and real hyperspectral images show the superior detection performance of the proposed method with a relatively high speed.     

The genesis of Mo-Cu deposits and mafic igneous rocks in the Senj area,Alborz magmatic belt,Iran

Mineralogy and Petrology - The geochemical and isotopic investigations were provided on the Upper Eocene Senj mafic intrusion and Mo-Cu mineralization to better understand the tectono-magmatic...     

Development of a new wavelet-based hybrid model to forecast multi-scalar SPEI drought index (case study: Zanjan city,Iran)

Theoretical and Applied Climatology - Drought forecasting plays a vital role in managing drought and reducing its effects on agricultural systems and water resources. In the present study, three...