Water leakage problems at the Tangab Dam Reservoir (SW Iran), case study of the complexities of dams on karst

Bulletin of Engineering Geology and the Environment - The Tangab Dam was constructed at a unique geological structure, within a karst valley at the deepest point of a saddle-shaped feature which...     

Integration of textual cues for fine-grained image captioning using deep CNN and LSTM

Neural Computing and Applications - The automatic narration of a natural scene is an important trait in artificial intelligence that unites computer vision and natural language processing. Caption...     

Removal of ciprofloxacin from aqueous solution by a continuous flow electro-coagulation process

This study deals with the performance and modeling of the electro-coagulation process for ciprofloxacin (CIP) removal by using aluminum electrode as anode in a continuous electrochemical reactor. The initial pH, temperature, current density, time and flow rate were selected as independent variables in response surface methodology (RSM) involving a five-level central composite design (CCD), while CIP removal efficiency was considered as the response function. The result of optimization showed that the maximum amount of CIP removal efficiency (88%) presented at the optimal condition of pH=5.6, t=100min, T=25.5 °C, I=5.6mA/cm² and V=25.9 mL/min. In addition, the mineralization of the CIP was investigated by chemical oxygen demand (COD) and total organic carbon (TOC) measurements that showed 77% COD removal and 49%TOC removal.     

Aerosol Process for the In Situ Coating of Nanoparticles with a Polymer Shell

This article presents a novel method to encapsulate gas-borne nanoparticles with a polymeric shell. This method implies heterogeneous condensation of monomer vapor around the surface of nanoparticles as nuclei and polymerization is then subsequently started by addition of NH₃ as aerosol initiator. Ag and SiO₂ nanoparticles were generated as inorganic core by spark discharge and nebulization, respectively, and glycidyl methacrylate (GMA) was used as organic monomer. The effect of several parameters, including vapor pressure of monomer and properties of inorganic core such as morphology, material, particle size, and production method on the thickness of polymeric shell and morphology of resulting nanocomposites has been investigated. The particle size distribution and morphology of the resulting core-shell nanoparticles have been studied via scanning mobility particle sizer (SMPS) and transmission electron microscope (TEM). Finally, the coating efficiency was determined by aerosol photoemission (APE) and the results show that monomer and polymer coating efficiency are 99% and 60%, respectively.

Copyright 2014 American Association for Aerosol Research     

Alkaline hydrolysis of the cyclic nitramine explosives RDX,HMX, and CL-20: new insights into degradation pathways obtained by the observation of novel intermediates

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX, I) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) hydrolyze at pH > 10 to form end products including NO2-, HCHO, HCOOH, NH3, and N2O, but little information is available on intermediates, apart from the tentatively identified pentahydro-3,5-dinitro-1,3,5-triazacyclohex-1-ene (II). Despite suggestions that RDX and HMX contaminated groundwater could be economically treated via alkaline hydrolysis, the optimization of such a process requires more detailed knowledge of intermediates and degradation pathways. In this study, we hydrolyzed the monocyclic nitramines RDX, MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine), and HMX in aqueous solution (pH 10-12.3) and found that nitramine removal was accompanied by formation of 1 molar equiv of nitrite and the accumulation of the key ring cleavage product 4-nitro-2,4-diazabutanal (4-NDAB, O2NNHCH2NHCHO). Most of the remaining C and N content of RDX, MNX, and HMX was found in HCHO, N2O, HCOOH, and NH3. Consequently, we selected RDX as a model compound and hydrolyzed it in aqueous acetonitrile solutions (pH 12.3) in the presence and absence of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) to explore other early intermediates in more detail. We observed a transient LC-MS peak with a [M-H] at 192 Da that was tentatively identified as 4,6-dinitro-2,4,6-triaza-hexanal (O2NNHCH2NNO2CH2NHCHO, III) considered as the hydrolyzed product of II. In addition, we detected another novel intermediate with a [M-H] at 148 Da that was tentatively identified as a hydrolyzed product of III, namely, 5-hydroxy-4-nitro-2,4-diaza-pentanal (HOCH2NNO2CH2NHCHO, IV). Both III and IV can act as precursors to 4-NDAB. In the case of the polycyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), denitration (two NO2-) also led to the formation of HCOOH, NH3, and N2O, but neither HCHO nor 4-NDAB were detected. The results provide strong evidence that initial denitration of cyclic nitramines in water is sufficient to cause ring cleavage followed by spontaneous decomposition to form the final products.     

Sono-Fenton regeneration of granular activated carbon saturated with Rhodamine B: Optimization using response surface methodology

This study investigated the combination of chemical and ultrasonic regeneration (Sono-Fenton), used for regenerating granular activated carbon (GAC) saturated with Rhodamine B (RB). This process was modeled and optimized using response surface methodology (RSM) based on central composite design (CCD). Effective parameters on regeneration efficiency such as pH, concentration of hydrogen peroxide (H₂O₂), and time of ultrasonic irradiation were optimized and modeled using the reduced quadratic method. The fitness of the model was checked by the determination coefficient (R²?=?0.9978). At optimum condition, the effective parameters of pH?=?3.84, concentration of H₂O₂?=?38.28 (mM), and time of ultrasonic irradiation?=?23.11(min), maximum regeneration efficiency (87.88%) was achieved, the results of which were obtained after four-time sequential adsorption–regeneration cycles were acceptable. Desorption and degradation of RB were conducted through the generation of active species, including hydroxyl radicals and high-energy ultrasound. The regeneration efficiency was increased using this combination method. In conclusion, the Sono-Fenton method is suggested to be used more widely in regeneration processes.     

Decoupled adaptive neuro-fuzzy (DANF) sliding mode control system for a Lorenz chaotic problem

This paper introduces a decoupled adaptive neuro-fuzzy (DANF) sliding mode control system for the chaos control problem in a system without precise system model information. It has on-line learning ability to deal with the parametric uncertainty and disturbance by adjusting the control parameters and no constrained conditions and prior knowledge of the controlled plant is required in the design process. Also, a decoupled adaptive sliding mode controller is developed to control the chaotic Lorenz system for comparison. Finally, the effectiveness of the proposed decoupled adaptive sliding mode and DANF sliding mode controllers are demonstrated by some simulated results.