Response of Bed Shear Stress in Open-Channel Flow to a Sudden Change in Bed Roughness

The estimation of bed shear stress plays a pivotal role in understanding the complexities of flow dynamics in both natural and engineered channels. The commonly employed log law formula offers a mechanism to compute the bed shear stress in open channel flows. However, its applicability in flow transition remains relatively unexplored. In this thesis, an in-depth investigation into the behavior of the velocity profiles and bed shear stress during the transition from Rough to Smooth (RTS) and Smooth to Rough (STR) beds is undertaken. Experiments were conducted on smooth-to-rough (STR) and rough-to-smooth (RTS) transitions in an open channel flume under different composite water surface profiles. The velocity field was measured at the channel centerline using a Particle Image Velocimetry (PIV) system. The bed shear stress was determined from the measured velocity profile and water depth using several methods. The primary objective was to investigate the effects of bed roughness and water surface profile on bed shear stress in gradually varied flow. This study found that in gradually varied flow through a roughness transition the evolution of bed shear stress was related to both the water surface profile and bed roughness. In both RTS and STR transitions, the bed shear stress adjusted to the new bed condition almost immediately even though the velocity profile away from the bed was still evolving. Unlike external and close-conduit flows, however, the bed shear stress in free-surface flow is also affected by the local water depth, and thus the composite water surface profile created by the channel transition. The bed shear stress development closely followed the variation in local water depth, ultimately reaching equilibrium when the flow depth became uniform. It was also found that the choice of the displacement height of the mean velocity profile played an important role in determining the bed shear stress on a rough bed using the logarithmic law, and thus the development of bed shear stress in smooth-to-rough transition

On Ground States and Phase Transition for λ\lambda-Model with the Competing Potts Interactions on Cayley Trees

In this paper, we consider the $\lambda$-model with nearest neighbor interactions and with competing Potts interactions on the Cayley tree of order-two. We notice that if $\lambda$-function is taken as a Potts interaction function, then this model contains as a particular case of Potts model with competing interactions on Cayley tree. In this paper, we first describe all ground states of the model. We point out that the Potts model with considered interactions was investigated only numerically, without rigorous (mathematical) proofs. One of the main points of this paper is to propose a measure-theoretical approach for the considered model in more general setting. Furthermore, we find certain conditions for the existence of Gibbs measures corresponding to the model, which allowed to establish the existence of the phase transition.Comment: 23 pages. arXiv admin note: text overlap with arXiv:1704.0193

λ-model with competing Potts interactions on Cayley tree of order 2

In this paper, we consider the λ-model on Cayley tree for order two with Potts competing nearest-neighbor and prolonged next-nearest neighbor-interactions. We described the construction of the Gibbs measure for the considered model. We proved the existence of the translation-invariant limiting Gibbs measures for the model

Optimization of biodiesel production from waste cooking oil using a green catalyst prepared from glass waste and animal bones.

Biodiesel as a fuel has been shown to positively impact the environment; replacing or reducing the dependence on fossil fuels while providing a viable alternative. The use of waste oils, such as non-edible or used oils, can reduce competition with food, loss of resources, and the resulting higher prices. In this study, biodiesel was obtained by a transesterification reaction using used cooking oil from fast-food restaurants as the feedstock and catalysts from waste glass and animal bones as the silica and calcium oxide sources, respectively. Utilizing waste or non-edible oils for the production of biodiesel can lessen the competition with food sources while achieving environmental and ethical biofuel standards. Additionally, employing readily available waste oils and catalysts prepared from waste material is an economical and low-cost process compared to the use of conventional expensive feedstock and catalyst. The catalyst characterization for the prepared CaO–SiO2 catalyst was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The reaction was optimized using the response surface methodology (RSM) with central composite design (CCD) by varying three parameters: methanol-to-oil ratio, catalyst weight fraction (wt%), and reaction time. The highest biodiesel yield obtained using Design Expert software was 92.3419% at the optimum conditions of a 14.83:1 methanol-to-oil molar ratio, 3.11 wt% catalyst, and 143 min reaction time. This proved that waste cooking oil with CaO–SiO2 catalyst could be used in the transesterification process to produce a high yield of biodiesel, which was shown in the results obtained from the experimental runs

Periodic and weakly periodic ground states for the λ-Model on Cayley tree

In this paper we consider the λ-model on the Cayley tree of order two. We describe the periodic and weakly periodic ground states for the considered model

Advances in Halloysite Nanotubes (HNTs)-Based Mixed-Matrix Membranes for CO2 Capture

Membrane technology promises a highly economical and efficient solution for CO2 separation. Many polymeric membranes have been reported in the past for the separation of gases specially to remove CO2 from natural gas and low-pressure flue-gas streams. The performance of membranes can be tailored by dispersing nanofillers in a polymeric matrix to produce mixed-matrix membranes (MMMs). This not only adds mechanical strength to membranes but also reduces compaction of the polymeric layer at high pressure and maintains high performance. Halloysite nanotubes (HNTs) gained attention in gas separation technology and due to their tubular structure have been used in a variety of applications in biomedical, coating, composite, and electronic industries. However, very little but conclusive literature and reviews are available to indicate that functionalized and non-functionalized HNTs can improve the performance of MMMs for efficient CO2 capture. The current status and gaps for potential applications of HNTs-based membranes for gas separation are identified and reviewed

Valorization of waste biomass to biofuels for power production and transportation in optimized way: a comprehensive review.

Fossil fuels are primary sources for energy production. Increased dependence on fossil fuels has resulted in increased environmental issues demanding alternative sources. Bioenergy is becoming a popular alternative energy source due to its positive environmental impact and the availability of renewable sources. However, the availability of renewable energy sources in the energy sector currently contributes to about 14%. Biofuels are preferred due to its sustainability, eco-friendly approach, and low-cost raw materials, making it an efficient technique for energy production. This article provides the fundamental and applied concepts for on conversion processes of biomass to biofuels, such as combustion, pyrolysis, fermentation, gasification, and anaerobic digestion along with their role in the green economy. Different physical characteristics of biomass resources are important and contribute to determining their potential for producing biofuels. Herein, LCA, its techno-economic importance, and the role of biomass in green economy are explained. Varying compositions and properties of different types of biomass resources, including lignocellulosic feedstocks, agriculture and forest residue, municipal solid waste, food waste, and animal manure as potential biomass resources, have been discussed. The article explains the strengths and weaknesses of different thermochemical conversion techniques and their current input toward scalar applications and commercialization

Big data analytics and innovation performance with the transformational role of management accountant

The purpose of this paper is to contribute to the literature on the impact of Big Data Analytics Capabilities (BDAC) on the Organizational Innovation Performance (OIP) with the transformational role of Management Accountant. By carrying out a literature review, this paper provides information for researchers and scholars to explore the emerging trends and implications of the above-mentioned relationship. A literature review highlights the emerging issues from the research conducted on Organizational Innovative Performance, Big Data and the role of Management Accountant in this relationship by focusing on: role of OIP, the importance of Big Data from the technological to the managerial paradigm as well as the role a Management Accountant can play in the era of Big Data. It is expected that identifying these contributions will help establish future research directions. The paper provides a number of avenues for potential research in this emerging area of investigation. The main aim of the key research questions posed is to further the contribution of Big Data towards research on Organizational Innovative Performance. The paper outlines how the organizations which are developing their approaches for big data analytics capabilities can focus on the factors and variables which are relevant for them to develop their big data analytics capabilities so as to develop their sustainable competitive advantages. This paper investigates the effects and implications which organizations can have by using Big Data to achieve innovative performance. At the same time, it provides an original understanding of the contextual importance of investing in the big data analytics capabilities development. It also considers the role played by management accountant as a bridge between the data scientists and the business requirements in a big data environment. As a result, the current study aims to show the impact which Big Data Analytics (BDA) Capabilities have on the organizational innovation performance with organizational culture and role of management accountant as moderators. The study will use data from surveys of CFOs, CEOs or CIOs of the pharmaceutical companies of Pakistan and will test a proposed model, using bootstrapped moderated analysis. This research considers the resource-based view of the firm as well as the socio-materiality theory. Practical implications for top executives are also discussed. There is a need to convert big data into meaningful information for strategic decision making. Management accountant plays vital role with the help of new skills set to develop newer expertise and make a bridge between data analysts and business executives as a moderator. To this end, this research focuses on identifying the gaps in the existing literature as well as proposing the course of action which can be undertaken for empirical study

Novel organometallic catalyst for efficient valorization of lipids extracted from Prunus domestica kernel shell in sustainable fuel production.

This study focuses on converting Plum Kernel Shell (PKS) waste biomass into biodiesel using a novel synthesized heterogeneous catalyst, contributing to the pursuit of renewable fuel from sustainable resources. Plum Kernel Shell (PKS) is waste biomass generated from plum fruit and available abundantly; utilizing it can help in many ways, such as overcoming environmental issues and promoting a circular economy. The precursor for the heterogeneous catalyst is derived from post-oil extraction waste biomass and further modified with metallic oxides (CuO and Mo) due to its acidic nature to enhance its efficacy for biodiesel production. Thorough characterization of the synthesized catalyst was conducted using analytical techniques such as XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), EDS (Energy-Dispersive X-ray Spectroscopy), BET (Brunauer-Emmett-Teller), and XPS (X-ray Photoelectron Spectroscopy) to elucidate its nature and performance. The transesterification process was systematically optimized by varying parameters such as temperature, time, methanol-to-oil ratio, and catalyst loading. The optimized yield of 92.61% of biodiesel resulted under ideal conditions, specifically at 65°C, 150 min, 5 wt% catalyst loading, and an 18:1 M ratio. The biodiesel derived from PKS oil exhibited promising fuel properties encompassing cold flow properties, density, viscosity, cetane number, and flash point, validating its potential as a viable alternative fuel source. Furthermore, the synthesized novel catalyst demonstrated exceptional efficiency, retaining stability over five cycles without significant reduction in biodiesel yield. These findings underscore the viability of PKS biomass as a renewable and sustainable source for both catalyst synthesis and biodiesel production

Enhanced solar light photocatalytic performance of Fe-ZnO in the presence of H2O2, S2O82−, and HSO5− for degradation of chlorpyrifos from agricultural wastes: Toxicities investigation

This study reported Fe doped zinc oxide (Fe-ZnO) synthesis to degrade chlorpyrifos (CPY), a highly toxic organophosphate pesticide and important sources of agricultural wastes. Fourier transform infrared, X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopic analyses showed successful formation of the Fe-ZnO with highly crystalline and amorphous nature. Water collected from agricultural wastes were treated with Fe-ZnO and the results showed 67% degradation of CPY by Fe-ZnO versus 39% by ZnO at 140 min treatment time. Detail mechanism involving reactive oxygen species production from solar light activated Fe-ZnO and their role in degradation of CPY was assessed. Use of H2O2, peroxydisulfate (S2O82−) and peroxymonosulfate (HSO5−) with Fe-ZnO under solar irradiation promoted removal of CPY. The peroxides yielded hydroxyl ([rad]OH) and sulfate radical ([Formula presented]) under solar irradiation mediated by Fe-ZnO. Effects of several parameters including concentration of pollutant and oxidants, pH, co-existing ions, and presence of natural organic matter on CPY degradation were studied. Among peroxides, HSO5− revealed to provide better performance. The prepared Fe-ZnO showed high reusability and greater mineralization of CPY. The GC-MS analysis showed degradation of CPY resulted into several transformation products (TPs). Toxicity analysis of CPY as well as its TPs was performed and the formation of non-toxic acetate imply greater capability of the treatment technology