Fast spectral solutions of the double-gyre problem in a turbulent flow regime

Several semi-analytical models are considered for a double-gyre problem in a turbulent flow regime for which a reference fully numerical eddy-resolving solution is obtained. The semi-analytical models correspond to solving the depth-averaged Navier–Stokes equations using the spectral Galerkin approach. The robustness of the linear and Smagorinsky eddy-viscosity models for turbulent diffusion approximation is investigated. To capture essential properties of the double-gyre configuration, such as the integral kinetic energy, the integral angular momentum, and the jet mean-flow distribution, an improved semi-analytical model is suggested that is inspired by the idea of scale decomposition between the jet and the surrounding flow

Green Synthesis of Silver Nanoparticles Induced by the Fungus Penicillium citrinum

Purpose: To evaluate a green process for the extracellular production of silver (Ag) nanoparticles synthesized and stabilized using Penicillium citrinum isolated from soil.Methods: The pure colonies of Penicillium citrinum were cultured in Czapek dox broth. The supernatant of the broth was examined for the ability to produce silver nanoparticles. The reactions were performed in a dark compartment at 28 oC. After 24 h, the synthesized silver nanoparticles were filtered through a membrane filter (0.45 ƒÊ) and characterized by UV-visible spectroscopy, fluorescence spectroscopy, photon correlation spectroscopy (PCS), scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR) for particle size, shape and the presence of different functional groups in the nanoparticles.Results: The silver nanoparticles formed were fairly uniform in size with a spherical shape and a Zaverage diameter of 109 nm. FTIR spectra revealed the presence of amide linkage groups which were also found in the fungal extract itself.Conclusion: The current approach suggests that rapid synthesis of nanoparticles of silver nitrate would be suitable for developing a biological process for mass scale production of formulations.Keywords: Green synthesis, Penicillium citrinum, silver nanoparticles

Groundwater augmentation through the site selection of floodwater spreading using a data mining approach (case study: Mashhad Plain, Iran)

© 2018 by the authors. It is a well-known fact that sustainable development goals are difficult to achieve without a proper water resources management strategy. This study tries to implement some state-of-the-art statistical and data mining models i.e., weights-of-evidence (WoE), boosted regression trees (BRT), and classification and regression tree (CART) to identify suitable areas for artificial recharge through floodwater spreading (FWS). At first, suitable areas for the FWS project were identified in a basin in north-eastern Iran based on the national guidelines and a literature survey. Using the same methodology, an identical number of FWS unsuitable areas were also determined. Afterward, a set of different FWS conditioning factors were selected for modeling FWS suitability. The models were applied using 70% of the suitable and unsuitable locations and validated with the rest of the input data (i.e., 30%). Finally, a receiver operating characteristics (ROC) curve was plotted to compare the produced FWS suitability maps. The findings depicted acceptable performance of the BRT, CART, and WoE for FWS suitability mapping with an area under the ROC curves of 92, 87.5, and 81.6%, respectively. Among the considered variables, transmissivity, distance from rivers, aquifer thickness, and electrical conductivity were determined as the most important contributors in the modeling. FWS suitability maps produced by the proposed method in this study could be used as a guideline for water resource managers to control flood damage and obtain new sources of groundwater. This methodology could be easily replicated to produce FWS suitability maps in other regions with similar hydrogeological conditions

Control Space Reduction and Real-Time Accurate Modeling of Continuum Manipulators Using Ritz and Ritz-Galerkin Methods

To address the challenges with real-time accurate modeling of multi-segment continuum manipulators in the presence of significant external and body loads, we introduce a novel series solution for variable-curvature Cosserat rod static and Lagrangian dynamic method. By combining a modified Lagrange polynomial series solution, based on experimental observations, with Ritz and Ritz-Galerkin methods, the infinite modeling state space of a continuum manipulator is minimized to geometrical position of a handful of physical points (in our case two). As a result, a unified easy to implement vector formalism is proposed for the nonlinear impedance and configuration control. We showed that by considering the mechanical effects of highly elastic axial deformation, the model accuracy is increased up to 6%. The proposed model predicts experimental results with 6-8% (4-6 [mm]) mean error for the Ritz-Galerkin method in static cases and 16-20% (12-14 [mm]) mean error for the Ritz method in dynamic cases, in planar and general 3D motions. Comparing to five different models in the literature, our approximate solution is shown to be more accurate with the smallest possible number of modeling states and suitable for real-time modeling, observation and control applications

APG: A novel Python-based ArcGIS toolbox to generate absence-datasets for geospatial studies

One important step in binary modeling of environmental problems is the generation of absence-datasets that are traditionally generated by random sampling and can undermine the quality of outputs. To solve this problem, this study develops the Absence Point Generation (APG) toolbox which is a Python-based ArcGIS toolbox for automated construction of absence-datasets for geospatial studies. The APG employs a frequency ratio analysis of four commonly used and important driving factors such as altitude, slope degree, topographic wetness index, and distance from rivers, and considers the presence locations buffer and density layers to define the low potential or susceptibility zones where absence-datasets are generated. To test the APG toolbox, we applied two benchmark algorithms of random forest (RF) and boosted regression trees (BRT) in a case study to investigate groundwater potential using three absence datasets i.e., the APG, random, and selection of absence samples (SAS) toolbox. The BRT-APG and RF-APG had the area under receiver operating curve (AUC) values of 0.947 and 0.942, while BRT and RF had weaker performances with the SAS and Random datasets. This effect resulted in AUC improvements for BRT and RF by 7.2, and 9.7% from the Random dataset, and AUC improvements for BRT and RF by 6.1, and 5.4% from the SAS dataset, respectively. The APG also impacted the importance of the input factors and the pattern of the groundwater potential maps, which proves the importance of absence points in environmental binary issues. The proposed APG toolbox could be easily applied in other environmental hazards such as landslides, floods, and gully erosion, and land subsidence

A randomized controlled multimodal behavioral intervention trial for improving antiepileptic drug adherence

Purpose: Medication nonadherence is one of the most important reasons for treatment failure in patients with epilepsy. The present study investigated the effectiveness of a multicomponent intervention to improve adherence to antiepileptic drug (AED) medication in patients with epilepsy. Methods: In a prospective, randomizedmulticenter trial, three sessions of face-to-facemotivational interviewing (MI) in combination with complementary behavior change techniques were compared with standard care.Motivational interviewing prompted change talk and self-motivated statements from the patients, planning their own medication intake regimen and also identifying and overcoming barriers thatmay prevent adherence. Participants were provided with calendars to self-monitor their medication taking behavior. A family member and the health-care teamwere invited to attend the last session ofMI in order to improve the collaboration and communication between patients, their caregiver or family member, and their health-care provider. At baseline and 6-month follow-up, psychosocial variables and medical adherence were assessed. Results: In total, 275 participantswere included in the study. Comparedwith the active control group, patients in the intervention group reported significantly highermedication adherence, aswell as stronger intention and perceptions of control for taking medication regularly. The intervention group also reported higher levels of action planning, coping planning, self-monitoring, and lower medication concerns. Conclusions: This study shows that MI can be effective in clinical practice to improvemedication adherence in patientswith epilepsy. It also provides evidence that combining volitional interventions, including action planning, coping planning, and self-monitoring withmotivational interviewing can promote the effectiveness of the medical treatments for epilepsy by improving adherenc

Scalable and Transfer-Free Fabrication of MoS2/SiO2 Hybrid Nanophotonic Cavity Arrays with Quality Factors Exceeding 4000

We report the fully-scalable fabrication of a large array of hybrid molybdenum disulfide (MoS2) -silicon dioxide (SiO2) one-dimensional, free-standing photonic-crystal cavities capable of enhancement of the MoS2 photoluminescence at the narrow cavity resonance. We demonstrate continuous tunability of the cavity resonance wavelength across the entire emission band of MoS2 simply by variation of the photonic crystal periodicity. Device fabrication started by substrate-scale growth of MoS2 using chemical vapor deposition (CVD) on non-birefringent thermal oxide on a silicon wafer;it was followed by lithographic fabrication of a photonic crystal nanocavity array on the same substrate at more than 50% yield of functional devices. Our cavities exhibit three dominant modes with measured linewidths less than 0.2 nm, corresponding to quality factors exceeding 4000. All experimental findings are found to be in excellent agreement with finite difference time domain (FDTD) simulations. CVD MoS2 provides scalable access to a direct band gap, inorganic, stable and efficient emitter material for onchip photonics without the need for epitaxy and is at CMOS compatible processing parameters even for back-end-of-line integration;our findings suggest feasibility of cavity based line-narrowing in MoS2-based on-chip devices as it is required for instance for frequency-multiplexed operation in on-chip optical communication and sensing

Distribution system protection by coordinated fault current limiters

The protection of distribution networks is one of the most substantial issues, which needs special attention. Using appropriate protective equipment enhances the safety of the power distribution network during the fault conditions. Fault current limiter (FCL) is a kind of modern preserving system being used for protecting power networks and equipment. One of the main concerns of power networks is the voltage restoration of buses during faulty conditions. In this study, a group of coordinated DC reactor type faults current limiters are designed and tested to protect the network and restore its buses voltage within the fault period. To coordinate FCLs and measurement devices during the fault sequences, a wireless communication system and decision-making computer are used. The proposed FCLs coordination strategy is modelled and simulated in MATLAB platform and the results are validated by the developed laboratory test setu

TMTDyn: A Matlab package for modeling and control of hybrid rigid–continuum robots based on discretized lumped systems and reduced-order models

A reliable, accurate, and yet simple dynamic model is important to analyzing, designing, and controlling hybrid rigid–continuum robots. Such models should be fast, as simple as possible, and user-friendly to be widely accepted by the evergrowing robotics research community. In this study, we introduce two new modeling methods for continuum manipulators: a general reduced-order model (ROM) and a discretized model with absolute states and Euler–Bernoulli beam segments (EBA). In addition, a new formulation is presented for a recently introduced discretized model based on Euler–Bernoulli beam segments and relative states (EBR). We implement these models in a Matlab software package, named TMTDyn, to develop a modeling tool for hybrid rigid–continuum systems. The package features a new high-level language (HLL) text-based interface, a CAD-file import module, automatic formation of the system equation of motion (EOM) for different modeling and control tasks, implementing Matlab C-mex functionality for improved performance, and modules for static and linear modal analysis of a hybrid system. The underlying theory and software package are validated for modeling experimental results for (i) dynamics of a continuum appendage, and (ii) general deformation of a fabric sleeve worn by a rigid link pendulum. A comparison shows higher simulation accuracy (8–14% normalized error) and numerical robustness of the ROM model for a system with a small number of states, and computational efficiency of the EBA model with near real-time performances that makes it suitable for large systems. The challenges and necessary modules to further automate the design and analysis of hybrid systems with a large number of states are briefly discussed