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Highlights • Computationally efficient geostatistical inversion. • High-dimensional optimization replaced by a sequence of one-dimensional optimizations. • Guarantees a monotonic decrease of the objective function. Abstract Geostatistical inverse modeling problems can potentially be very high-dimensional and computationally expensive. Using the Random Mixing approach the dimensionality can be reduced, and any optimization algorithm can be applied to solve the inverse problem in this lower dimensional space. In order to reduce computational costs the standard optimization is replaced by a sequence of one-dimensional optimizations. In this one-dimensional space a simplified calculation of the objective function using Whittaker–Shannon interpolation is carried out. This procedure requires a significantly reduced number of forward model runs and it also guarantees monotonic convergence of the objective function. A synthetic and a real world example will be used to demonstrate the procedure and to evaluate the quality of the Whittaker–Shannon interpolation in comparison to the actual objective functions. [ABSTRACT FROM AUTHOR]

Large scale development of coal seam gas (CSG) is occurring in many sedimentary basins around the world including Australia, where commercial production of CSG has started in the Surat and Bowen basins. CSG development often involves extraction of large volumes of water that results in depressurising aquifers that overlie and/or underlie the coal seams thus perturbing their flow regimes. This can potentially impact regional aquifer systems that are used for many purposes such as irrigation, and stock and domestic water. In this study, we adopt a probabilistic approach to quantify the depressurisation of the Gunnedah coal seams and how this impacts fluxes to, and from the overlying Great Artesian Basin (GAB) Pilliga Sandstone aquifer. The proposed method is suitable when effects of a new resource development activity on the regional groundwater balance needs to be assessed and account for large scale uncertainties in the groundwater flow system and proposed activity. The results indicated that the extraction of water and gas from the coal seam could potentially induce additional fluxes from the Pilliga Sandstone to the deeper formations due to lowering pressure heads in the coal seams. The median value of the rise in the maximum flux from the Pilliga Sandstone to the deeper formations is estimated to be 85 ML/year, which is considered insignificant as it forms only about 0.29% of the Long Term Annual Average Extraction Limit of 30 GL/year from the groundwater management area. The probabilistic simulation of the water balance components indicates only small changes being induced by CSG development that influence interactions of the Pilliga Sandstone with the overlying and underlying formations and with the surface water courses. The current analyses that quantified the potential maximum impacts of resource developments and how they influences the regional water balance, would greatly underpin future management decisions. [ABSTRACT FROM AUTHOR]

Two novel, highly soluble and semiconducting thienylene–biphenylenevinylene hybrid polymers with excellent photoluminescence and thermal stability were synthesized via Stille coupling polymerization of two novel monomers 5,5′-(1 E ,1′ E )-2,2′-(4,4′-bis(octyloxy)biphenyl-3,3′-diyl)bis(ethene-2,1-diyl)bis(2-bromothiophene) and 5,5′-(1 E ,1′ E )-2,2′-(6,6′-bis(octyloxy)biphenyl-3,3′-diyl)bis(ethene-2,1-diyl)bis(2-bromothiophene), respectively. The structural, thermal, optical and electrical characteristics of the synthesized monomers and polymers were studied in detail. Both polymers exhibit good solubility in common organic solvents, high thermal stability and desirable photophysical characteristics. Slight differences in the optical and electrical properties were observed for both the polymers which arise as a result of the positional change introduced to the functional groups attached in the polymer backbones. Hybrid density functional theory was used to study the band structure of the polymers and the values agree with the experimental results. Polymer light emitting diodes (PLEDs) were assembled based on these hybrid polymers as emissive layers and characterized to establish the suitability of these materials for PLED application. The assembled PLEDs show excellent diode characteristics and good emission in the orange red region. [ABSTRACT FROM AUTHOR]

This study develops a methodology based on simulation-optimization to derive optimal combined operation plans for the management of production and barrier wells in a coastal aquifer in order to ensure the sustainable use of the fresh water resource. A numerical model for the simulation of saltwater intrusion process, a neural network based meta-model and a multi-objective genetic al-gorithm are used in a linked simulation-optimization approach to develop the management model. The pumping strategies derived using the management model was found to be effective in finding optimal and sustainable operation strategies for coastal well fields by controlling saltwater intrusion. [ABSTRACT FROM AUTHOR]

Parameterization strategy impacts models' outputs and the associated uncertainty. This is particularly true for transient regional groundwater models where parameters can only be weakly constrained by insufficient observations. However, this is rarely investigated under any particular model structure. This study bridges this gap using a regional groundwater model developed to understand the impact of coal seam gas extraction on groundwater systems in a probabilistic framework. Two different parameterization schemes were implemented for hydraulic conductivity and specific storage. The first method solely relies on the relationship between hydraulic properties and burial depths. The second more complex strategy allows more spatial variations of hydraulic parameters using pilot points. The study provides new insights and practical guidance on the application of groundwater modelling for environmental impact assessment. The results suggest that the choice of model parameterization has a significant influence on predictive uncertainty. The model using the simple parameterization provides predictions with a much wider range than the model with a more sophisticated parameterization. This is because that the lowly parameterized model tends to generate more extreme effective hydraulic parameter fields unless the parameterization simplification converts the inverse problem to a (close to) well-posed problem that rarely exists for applied regional groundwater modelling. The potential impact of model parameterization should be discussed explicitly in groundwater modelling applications to support decision making to avoid misinterpretation of the modelling results. • Impact of parameterization on uncertainty is significant • With weak constraining, simple model tends to generate more extreme predictions • The findings are critical for decision-making based on groundwater modelling [ABSTRACT FROM AUTHOR]

This study focuses on the analyses of influx and efflux of groundwater at the aquifer−sea interface in response to the total groundwater extraction from a regional coastal aquifer. The groundwater planning and management goal is formulated as a multi-objective optimization problem to optimize the total pumping, groundwater influx and efflux through the coastal boundary. A four-stage optimization strategy is implemented for solving this optimization problem, whereby the first three stages are the iterative optimizations using the proposed Multi-Objective Particle Swarm Optimization algorithm and the analysis of Pareto-optimal solutions, and the last stage is the selection of one bargaining solution using the Kalai-Smorodinsky approach considering compromises among multiple objectives. In order to improve the efficiency of the simulation-optimization model, Deep Neural Networks emulators are fitted to approximate individual optimization objective, and a novel dynamic sampling strategy is applied to adaptively improve the accuracy of the emulators. This study demonstrates that accurate and efficient emulators can be achieved for the regional coastal aquifer with zone-based pumping rate multipliers from eight bands (Band 1 to Band 8) of increasing distance from the coastal boundary as the decision variables. The results from the Pareto-front suggest that the abstractions of Band 2 (close to the sea) can be reduced to the lower boundary of the rate multiplier (0.5) whereas the abstraction of farther bands can be significantly enhanced. The water influx through the coastal boundary was decreased by 15.69% under the slight compromise of the total pumping and water efflux by the selected compromising pumping pattern in the regional model. The final Pareto-optimal solution set and the compromised solution provide valuable information for the groundwater manager to plan sustainable groundwater use. The proposed simulation-optimization approach used in this study can be applied for a wide range of groundwater management problems. ga1 • Deep-learning assisted Multi-Objective Particle Swarm Optimization for coastal aquifer management. • Multi-stage adaptive training of DNN-based emulators to achieve improved solutions for management. • Kalai−Smorodinsky approach for selecting an ideal solution from Pareto-front. • Adjusting abstraction to the farther zones from the coast benefits this over-extraction system. [ABSTRACT FROM AUTHOR]

Two novel, soluble, semiconducting and light emitting segmented block copolymers, termed as NPPV1 and NPPV2 are synthesized using Horner-Emmons condensation polymerization. The chromophoric groups present in the copolymers are distyrylbenzene (DSB) units substituted with rigid, bulky cyclohexylmethoxy and cyclohexylethoxy groups. The rigid blocks are linked to flexible α,ω-nonamethylenedioxy chain spacer through ether linkage. The structural, morphological, thermal and photo-physical characteristics of the synthesized polymers are studied in detail. Noticeable differences in properties arising through the substituent effects are observed for both the polymers. Detailed studies bring out quite interesting structure-property relationships between the substituents introduced in the synthesized copolymers and their crystalline properties, thermal characteristics, optical properties, photoluminescence emission and fluorescence quantum yield. Polymer light emitting diodes (PLEDs) employing these segmented polymers as emissive layers are assembled and characterized to establish their suitability for lighting applications. Using the architecture, ITO/PEDOT:PSS/ NPPV1/ LiF-Al, polymer light emitting diodes (PLEDs) are assembled and as the first step of device characterization, their current-voltage characteristics are studied to establish the device behavior and find out the onset voltage. The emission characteristics of the devices are then studied using Ocean Optics USB 2000 spectrometer integrated to a computer using a dedicated program. The assembled devices show Schottky junction like behavior in the current-voltage characteristics and electroluminescence emission in the blue green region with appreciable intensity at the onset voltage of 8.8 V. It is highly desirable to develop polymers showing emission in the high frequency,blue region, using cost-effective synthesis routes. The novel approaches adopted in the synthesis of the monomers and the corresponding copolymers to achieve the anticipated structure-property relationships suitable for the effective designing of polymer light emitting diodes are the highlights of the present work. Image 1 • Two novel, light emitting, segmented block copolymers NPPV1 and NPPV2 are synthesized. • Structure-property relationships of these polymers are tuned to facilitate the designing of PLEDs. • The PLEDs with the configuration, ITO/PEDOT:PSS/NPPV1/LiF-Al are assembled and characterized. • The PLEDs show electroluminescence in the blue green region with good intensity. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Although quantum dots (QDs) based on two dimensional (2D) materials have manifested fascinating properties and promising applications in a wide range of fields, a low cost and non-tedious approach for the preparation of atomically thick 2D QDs with high yield remains elusive. Herein, for the first time, we demonstrate a reflux pretreatment-mediated sonication approach to produce a series of ultrathin 2D QDs (e.g., graphene, TiS 2 , MoS 2 , MoSe 2 , WSe 2 , NbS 2 , SnS 2 , and h-BN QDs) from their bulk counterparts. The solvent molecules, confined in the channels of layered materials during reflux, assist the delamination and fracture of 2D sheets in the process of bath sonication. The resulting 2D QDs exhibited uniform lateral size distribution of 2–7 nm and a mean thickness of 0.8–1 nm, almost identical to the monolayer thickness of layered materials. To demonstrate the unique property of these 2D QDs, the optical limiting activity was studied using open aperture z-scan technique. TiS 2 QDs exhibited appreciable nonlinear optical limiting, reaching 50% by a tapered and sharp absorption at input laser fluence of 4.24 GW/cm2. [ABSTRACT FROM AUTHOR]