Geological carbon storage is one of the technologies required to arrive at the ambitious yet realistic net-zero emission target and climate change neutrality. Injected CO2 in geological formations ...acidifies the resident brine, inducing chemical reactions with the minerals. Reactions may alter the hydraulic and mechanical properties of the rock and have an impact on reservoir and wellbore integrity, reservoir injectivity, long-term compaction and caprock sealing capacity. We provide a comprehensive review of chemo-hydro-mechanical (CHM) effects of CO2 on the reservoir and sealing rocks, either intact or fractured, which have been studied through laboratory experiments under no-flow and open-flow conditions, i.e., batch and flow-through experiments. The hydraulic and mechanical rock properties affected by geochemical processes comprise (a) physical properties influencing the flow and transport of solutes (pore size distribution, porosity, permeability and fracture aperture and roughness), (b) multi-phase flow properties (capillary entry pressure and relative permeability), (c) mechanical characteristics, including stiffness (i.e., elastic moduli for intact rocks and normal stiffness for fractures), strength (cohesion, friction angle and fracture toughness), and poroelastic response (Biot's coefficient), and (d) time-dependent behavior of the rock (compaction creep). The experiments alone cannot capture the complex dynamics of CO2 flow underground, but they provide critical insights into short-term alteration mechanisms of rock with implications to geologic CO2 storage. Studying naturally altered rocks, extending the experiments to tens-of-meters-scale underground rock laboratories, and bringing together experimental observations and numerical simulations are valuable for the advance in the understanding of CHM processes and upscaling them across space and time.
•CO2 interactions with intact/fractured rocks alter their hydromechanical properties..•Content and distribution of reactive minerals determine the extent of interactions..•Notable alterations of carbonates are only anticipated under open-flow conditions..•Sandstones with reactive cement minerals are prone to remarkable mechanical weakening..•Hydromechanical changes in shales show inconsistencies and need further study..
This paper studies three continuous review economic order quantity models for time-dependent deterioration using preservation technology. First, a crisp model is developed and the model is extended ...into a fuzzy model to include the imprecise nature of demand. It is further extended to analyze the impact of the learning effect under the fuzzy environment. All models are developed for a finite time horizon, incorporating promotional effort and full backorder. The optimal solutions are derived for the number of orders, preservation technology cost, and the fraction of a cycle with positive stock. Three algorithms are developed to find the optimal solution for three models. Numerical analysis is performed to demonstrate the application, followed by a sensitivity analysis of the important parameters. The crisp model leads to the lowest total cost followed by fuzzy learning and fuzzy model. Even though the optimal number of orders is found to be the same for the three models, order quantity is more for the fuzzy model and less for the crisp model. The order quantity increases step-wise with an increase in preservation factor.
•Impact of preservation for imprecise demand.•Use of preservation against Time-dependent deterioration.•Reduction in impreciseness through learning.•Three improved algorithms are designed to solve the model.
We show that by using the quantum orthogonal functions invariant, we found a solution to coupled time-dependent harmonic oscillators where all the time-dependent frequencies are arbitrary. This ...system may be found in many applications such as nonlinear and quantum physics, biophysics, molecular chemistry, and cosmology. We solve the time-dependent coupled harmonic oscillators by transforming the Hamiltonian of the interaction using a set of unitary operators. In passing, we show that N time-dependent and coupled oscillators have a generalized orthogonal functions invariant from which we can write a Ermakov–Lewis invariant.
We study two schemes for a time-fractional Fokker-Planck equation with space-and time-dependent forcing in one space dimension. The first scheme is continuous in time and discretized in space using a ...piecewise-linear Galerkin finite element method. The second is continuous in space and employs a time-stepping procedure similar to the classical implicit Euler method. We show that the space discretization is second-order accurate in the spatial L₂-norm, uniformly in time, whereas the corresponding error for the time-stepping scheme is O(kα) for a uniform time step k, where α ϵ (1/2, 1) is the fractional diffusion parameter. In numerical experiments using a combined, fully discrete method, we observe convergence behavior consistent with these results.
The partial differential equation (PDE)-based models are widely used to remove additive Gaussian white noise and preserve edges, and one of the most widely used methods is the total variation ...denoising algorithm. Total variation (TV) denoising algorithm-based time-dependent models have seen considerable success in the field of image-denoising and edge detection. TV denoising algorithm is based on that signals with spurious detail have a high total variation and reduction of unwanted signals to achieve noise-free images. It is a constrained optimization-type algorithm. The Lagrange multiplier and gradient descent method are used to solve the TV algorithm to reach the PDE-based time dependent model. To eliminate additive noise and preserve edges, we investigate a class of weighted time-dependent model in this study. The proposed method is investigated in a well-balanced flow form that extends the time-dependent model with an adaptive fidelity element. Adaptive function is fusing into the regularization term of the classical time-dependent model which successfully enhances the intensity of the regularizer function. We maintain the ability of the time-dependent model without any oscillation effects. Furthermore, we want to prove the viscosity solution of our weighted and well balanced time-dependent model, demonstrating its existence and uniqueness. The finite difference method is applied to discretize the nonlinear time-dependent models. The numerical results are expressed as a statistic known as the peak signal-to-noise ratio (PSNR) and structural similarity index metric (SSIM). Numerical experiments demonstrate that the proposed model yields good performance compared with the previous time-dependent model.
•Develop integer programming models to design train timetables in a heavily congested urban rail corridor.•Analytically calculate effective passenger loading time periods under dynamic demand ...patterns.•Calculate time-dependent waiting times under oversaturated conditions.•Propose gradient-based and genetic algorithms for optimizing timetables.
This article focuses on optimizing a passenger train timetable in a heavily congested urban rail corridor. When peak-hour demand temporally exceeds the maximum loading capacity of a train, passengers may not be able to board the next arrival train, and they may be forced to wait in queues for the following trains. A binary integer programming model incorporated with passenger loading and departure events is constructed to provide a theoretic description for the problem under consideration. Based on time-dependent, origin-to-destination trip records from an automatic fare collection system, a nonlinear optimization model is developed to solve the problem on practically sized corridors, subject to the available train-unit fleet. The latest arrival time of boarded passengers is introduced to analytically calculate effective passenger loading time periods and the resulting time-dependent waiting times under dynamic demand conditions. A by-product of the model is the passenger assignment with strict capacity constraints under oversaturated conditions. Using cumulative input–output diagrams, we present a local improvement algorithm to find optimal timetables for individual station cases. A genetic algorithm is developed to solve the multi-station problem through a special binary coding method that indicates a train departure or cancellation at every possible time point. The effectiveness of the proposed model and algorithm are evaluated using a real-world data set.
Arsenic (As) is a toxic metalloid posing harming the human food chain through trophic transfer. Microalgae are primary producers, ensuring bioaccumulation and biogeochemical cycling of As in water ...environment. They are highly efficient at removing As from the environment, making these microscopic organisms eco-friendly and money saving method in As remediation process. However, microalgal growth and As biotransformation potential relies greatly on individual and integrated environmental factors. This review scrutinizes the available literature on the As biotransformation potentials of various marine and freshwater microalgae under individual and integrated stresses of such factors. Various combinations of important factors such as temperature, salinity, concentrations of As (V) and PO43─, pH, light intensity, and length of exposure period are summarized along with the optimum conditions for different microalgae. The effects of environmental factors on microalgal growth, changes in cell shape, and the relationship between As biotransformation and other activities are discussed in detail. Time-dependent As speciation pattern by aquatic microalgae are reviewed. Conceptual models highlighting the microalgal species particularly linked with environmental factor-dependent As biotransformation mechanisms are also summarized. This review will contribute to an in depth understanding of the connection between environmental factors, As uptake, and the biotransformation mechanism of marine and freshwater microalgae from the perspective of As remediation process.
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•Integrated effects of environmental factors on As biotransformation are reviewed.•Time-dependent As speciation pattern are scrutinized under combined factors.•Environmental factor-dependent As biotransformation mechanisms are summarized.•Review will contribute to know As detoxification mechanism under integrated stress.
•Novel D-D-π-A structured indole-based compounds have been designed and synthesized for dye-sensitized solar cells (DSSCs).•D-D-π-A structured indole-based compounds consist of two different donors ...namely carbazole-indole, dibenzofuran-indole and 1,4-benzodioxane-indole, which are linked to an acceptor unit cyanoacetic acid through a π-spacer.•The current work investigated the synthesized compound's attributes in terms of photophysical, electrochemical, redox behavior, HOMO/LUMO level and light-harvesting efficiency (LHE).•All compounds displayed distinct absorption with robust absorptivity and a minor band gap ranging from 2.82 to 2.93 eV.•The calculated light-harvesting efficiency (LHE) for the targeted D-D-π-A compounds is between 0.465 to 0.661.
Herein, we report three novel indole-based D-D-π-A formulated compounds, that have been synthesized to act as active and dynamic photosensitizers for dye-sensitized solar cells (DSSCs). The D-D-π-A structured indole-based compounds designed as the continuation of our prior work, newly synthesized compounds consist of two different donors namely carbazole-indole, dibenzofuran-indole and 1,4-benzodioxane-indole, which are linked to an acceptor unit cyanoacetic acid through a π-spacer. IR, NMR and HRMS spectral data were utilized to recognize and characterize the molecular structures of targeted indole-based D-D-π-A compounds. The current work investigated the synthesized compound's attributes in terms of photophysical, electrochemical, redox behavior, theoretical HOMO/LUMO level and light-harvesting efficiency (LHE). All compounds displayed distinct absorption with robust absorptivity and a minor band gap ranging from 2.82 to 2.93 eV. To reveal the electronic and optical features of synthesized D-D-π-A structured compounds, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used. The energy transfer percentage of synthesized compounds HOMO to LUMO is 99 %. The calculated light-harvesting efficiency (LHE) for the targeted D-D-π-A compounds is between 0.465 to 0.661. Moreover, the carbazole-indole D-D-π-A structured compound had the highest open circuit voltage (Voc) value, a crucial factor for DSSCs to achieve their maximum external power output.
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