Potential Energy Research Articles

Latent-to-sensible heat conversion kinetics during nanoparticle coalescence.

Coagulational growth in an aerosol is a multistep process; first particles collide, and then they coalesce with one another. Coalescence kinetics have been investigated in numerous prior studies, largely through atomistic simulations of nanoclusters (102-104 atoms). However, with a few exceptions, they have either assumed the process is completely isothermal or is a constant energy process. During coalescence, there is the formation of new bonds, decreasing potential energy, and correspondingly increasing internal kinetic (thermal) energy. Internal kinetic energy evolution is dependent not only on coalescence kinetics but also on heat transfer to the surrounding gas. Here, we develop and test a model of internal kinetic energy evolution in collisionally formed nanoclusters in the presence of a background gas. We find that internal kinetic energy dynamics hinge upon a power law relationship describing latent-to-sensible heat release as well as a modified thermal accommodation coefficient. The model is tested against atomistic models of 1.5-3.0nm embedded-atom gold nanocluster sintering in argon and helium environments. The model results are in excellent agreement with the simulation results for all tested conditions. Results show that nanocluster effective temperatures can increase by hundreds of Kelvin due to coalescence, but that the rise and re-equilibration of the internal kinetic energy is strongly dependent on the background gas environment. Interestingly, internal kinetic energy change kinetics are also found to be distinct from surface area change kinetics, suggesting that modeling coalescence heat release solely due to surface area change is inaccurate.

Organo‐Soluble Colloidal MoS2 Quantum Dots (QDs) as an Efficient Photocatalyst for α‐Amino Phosphonate Synthesis

Abstractα‐Amino phosphonates are bio‐isosteres of amino acids and have numerous biochemical activities. While they are generally prepared via carbon–phosphorus bond formation using a plethora of methods but using recyclable photo‐catalysts and readily accessible amine and phosphites are not commonly used in synthesis. Herein, we used organo‐soluble MoS2 Quantum Dots (QDs) as an exceptionally efficient nano‐photocatalyst for the synthesis of α‐amino phosphonates. Our approach emphasizes on photocatalysis within organic media, providing a facile and effective method for conducting these intricate organic conversions under mild conditions. This straightforward process harnesses the power of molecular oxygen (O2) as an oxidizing agent. To elaborate, our method is intricately guided by the inherent capability of MoS2 QDs to enter an excited state upon absorption of blue light. This excited state bears appropriate potential energy to initiate the formation of reactive iminium ion species from N‐phenyl benzylamine, thus driving the desired product formation. Mechanistic analysis has also unveiled the pivotal role of MoS2 QDs in generating reactive superoxide radicals from O2 through single electron transfer (SET), underscoring their significance in the process. Remarkably, this photocatalytic transformation furnishes a diverse array of functionalized products, expanding its applicability and potential implications in various contexts.

A fast and smooth one-electron approach for investigating charge transfer states and D1-D0 crossings for systems with odd numbers of electrons.

We propose an efficient version of ensemble Hartree-Fock/density functional theory to calculate a set of two charge-transfer states for systems with odd-numbers of electrons. The approach does require definitions of donor/acceptor fragments; however, the approach is not very sensitive to such definitions-even in the limit of very strong electronic coupling. The key ansatz is that, by mandating that the vector space spanned by the active orbitals projects equally onto the donor and acceptor fragments, such a constraint eliminates all intra-molecular local excitations and makes it far easier to generate potential energy surfaces that are smooth over a wide region of configuration space. The method is fast, working with only two electron configurations, and should be useful for abinitio non-adiabatic dynamics in the near future.

A method for predicting deformation field of deep foundation pit considering spatial effect

Urban underground spaces have experienced significant development and utilization due to the rapid progress of urban construction and continuous advancements in construction technology. The number of foundation-pit projects immediately adjacent to buildings, structures, and pipelines has been increasing. Ensuring the safety of construction and surrounding facilities, it is essential to predict deformation caused by foundation pit excavations. In this study, a simple calculation method was proposed for predicting deformation of an envelope structure and surface settlement caused by deep foundation excavation with spatial effects. Firstly, the principle of minimum potential energy was applied and the lateral displacement equation of the envelope structure was derived, considering spatial deformation effects. Secondly, based on linear elasticity theory, a surface settlement expression was formulated utilizing the plane strain boundary. Finally, the stratigraphic loss method was used to establish a connection between horizontal envelope deformation and surface settlement, allowing for calculations of surface settlement at any position behind the envelope structure. The effectiveness and practicability of the proposed method were demonstrated by comparison of two existing foundation-pit engineering examples.

Enhancing Molecular Energy Predictions with Physically Constrained Modifications to the Neural Network Potential.

Exclusively prioritizing the precision of energy prediction frequently proves inadequate in satisfying multifaceted requirements. A heightened focus is warranted on assessing the rationality of potential energy curves predicted by machine learning-based force fields (MLFFs), alongside evaluating the pragmatic utility of these MLFFs. This study introduces SWANI, an optimized neural network potential stemming from the ANI framework. Through the incorporation of supplementary physical constraints, SWANI aligns more cohesively with chemical expectations, yielding rational potential energy profiles. It also exhibits superior predictive precision compared with that of the ANI model. Additionally, a comprehensive comparison is conducted between SWANI and a prominent graph neural network-based model. The findings indicate that SWANI outperforms the latter, particularly for molecules exceeding the dimensions of the training set. This outcome underscores SWANI's exceptional capacity for generalization and its proficiency in handling larger molecular systems.

A comparative study of analytical representations of potential energy curves for CO in its ground electronic state

AbstractIn this work, a comparative study of four functional forms used to represent potential energy curves (PECs) is presented. The starting point is the Hulburt‐Hirschfelder, followed by the Extended Rydberg potential function, ending with two of the most recent potentials presented in the literature for diatomic systems: the Araújo‐Ballester potential and the Improved Extended Lennard‐Jones potential. The chosen potentials have in common the fact that all their parameters are algebraically calculated, without any fitting procedure, and all of them have direct dependence on Dunham's parameters. The mathematical behavior of these functions for the short‐ and long‐range regions is discussed. As study case, the diatomic system in its ground electronic state was selected. To quantify the accuracy of the potential energy functions, the least‐squares Z‐test method, proposed by Murrell and Sorbie, is used. Furthermore, the main spectroscopic constants and vibrational energy levels are calculated and compared for all potentials.

METHODS OF INFLUENCE ON THE SYSTEM TO CHANGE THE ENERGY STATE OF SUBSTANCE: EXPERIENCE, STATE OF THE ISSUE

Methods of influencing the system, the ultimate goal of which is to destruct the natural structure of the material, can be divided as mechanical, physical, chemical, biological and complex. The changing the energy state of a substance is called activation. The current scientific field of ultradispersed materials and physical and chemical processes caused by dispersion is created by the researches of many scientists. Detailed consideration for the increasing reactivity of a solid substance compared to the change in its specific surface area during its mechanical activation showed that the share attributable to the growth of the specific surface area is only a few percent of the mechanical activation effect. The other part is due to the accumulation of defects in the crystals during the grinding process. According to the law of conservation of energy, when a crystal splits, the potential energy of interaction between lattice nodes is transferred to uncompensated surface energy. In addition, the value of the specific surface energy depends on the type of flat lattice used to split the crystal. Therefore, the activation processes and the application of the substance in the active state are relevant in the development of modern binders and concretes. The purpose of the article is to analyse the advantages and disadvantages of the existing methods of influencing the system with the ultimate goal of destruction of the natural structure of the material to changing the energy state of the substance, i.e. its activation. Conclusions. During the destruction of solids, the formation of new cleavage surfaces is accompanied by the breaking of bonds between the substance structural elements and the transition of the potential bond energy into surface energy. Ceteris paribus, the higher the ionic charges and the smaller the distance between them (between adjacent flat grids in the lattice), the greater the value of σ. In addition, the value of the specific surface energy depends on the type of flat grids used to split the crystal. It is worth mentioning that not all methods of activation for binder and concrete (soluble) mixtures are currently implemented on an i industry level. This is due to various reasons. The main method of activation used on an industry level is mechanochemical activation in various types of mills.

Greenhouse gas emission implications of small-scale sugarcane farmers’ trash management practices: A case for bioenergy production in South Africa

Sugarcane trash is a source of biomass available for energy generation. However, this potential has not been explored in the South African small-scale sugarcane sector. The current trash management practices of farmers, especially, pre-harvest burning, have huge negative environmental implications. Sustainable management of sugarcane trash could help address several challenges in the sugarcane industry including the high cost of irrigation. Therefore, this study is meant to assess small-scale growers’ trash management practices and their implications on greenhouse gas emissions. It also ascertains the potential for using sugarcane trash in the co-generation of electricity. The study was conducted in two communities in KwaZulu-Natal and Mpumalanga provinces with 330 small-scale farmers. A probit regression was used to determine factors that influence farmers’ trash management practices. Other analyses such as estimations of the amount of available trash, burning emissions and potential energy from sugarcane were informed by previous studies. The findings showed that pre-burning of sugarcane is a common practice among smallholder producers in South Africa. However, some farmers have attempted to move away from this practice opting to leave their sugarcane in the field or use it for compost. The farmers’ burning of sugarcane releases an estimated 0.08 tCO2-e per ha into the atmosphere. In total, the estimated greenhouse gas emissions from sugarcane burning of all small-scale growers in the two provinces are 725 tCO2-e per annum. The findings also revealed that having more land, poor endowment with psychological capital, lack of access to extension, limited resources, and working in silos compound the practice of burning sugarcane. The estimated energy potential from small-scale sugarcane producers in the country, using a 50 % recovery efficiency and 36 % energy conversion efficiency is 150,323.3 MWh. The study proposes several recommendations for improving trash management practices and initiating the co-generation of electricity from trash in the small-scale sugarcane industry.

Efficiency of Renewable Energy Sources in Reducing Carbon Footprint in Developing Countries

Purpose: The aim of the study was to examine efficiency of renewable energy sources in reducing carbon footprint in developing countries Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study demonstrated the effectiveness of various renewable energy technologies, such as solar photovoltaic systems, wind power, biogas technology, and hydropower, in mitigating carbon emissions and promoting sustainable development. These technologies offer reliable, environmentally friendly alternatives to fossil fuels, contributing to enhanced energy access, reduced reliance on traditional biomass fuels, and positive socio-economic impacts. However, realizing the full potential of renewable energy requires addressing barriers such as upfront costs, financing constraints, and technical capacity limitations. Policy interventions play a crucial role in scaling up renewable energy deployment through targeted incentives, regulatory frameworks, and capacity-building initiatives. Unique Contribution to Theory, Practice and Policy: Technology Adoption Theory, Environmental Policy Theory & Energy Transition Theory may be used to anchor future studies on efficiency of renewable energy sources in reducing carbon footprint in developing countries. Implement practical measures to facilitate technology transfer and capacity building in renewable energy sectors. This involves partnerships between developed and developing countries to share knowledge, expertise, and resources for deploying and maintaining renewable energy infrastructure. Establish supportive regulatory frameworks that streamline permitting processes, ensure grid integration, and provide market access for renewable energy producers. Clear and consistent regulations create an enabling environment for renewable energy investments and facilitate the transition to low-carbon energy systems.

Inversion of gas hydrate saturation and solid frame permeability in a gas hydrate-bearing sediment by Stoneley wave attenuation

Natural gas hydrate is a potential novel energy resource widely distributed globally. Acoustic logging can effectively provide information on the surrounding reservoir and plays an important guiding role in gas hydrate exploration and development. Natural gas hydrate-bearing sediments are composed of a solid frame with natural gas hydrates and water filled pores. The borehole mode wave characteristics of two-phase porous media can’t be used to evaluate the parameters of such a multi-phase porous medium. We explore factors that influence the monopole Stoneley wave in a borehole embedded in a multi-phase porous medium containing two solids and one fluid and analyze the influence of each factor on monopole Stoneley wave attenuation systematically. The sensitivity analysis results indicate that the Stoneley wave attenuation is highly sensitive to solid frame permeability and gas hydrate saturation. Building upon this foundation, a method to invert for gas hydrate saturation and solid frame permeability is first developed using Stoneley wave attenuation. Synthetic logging data is used to demonstrate the feasibility of this method for inverting for gas hydrate-bearing sediment properties. Even in the presence of considerable noise added to the receiver signal arrays, the inversion method is stable and reliably evaluates gas hydrate saturation and solid frame permeability.

Site Selection for Offshore Wind Power Farms with Natural Disaster Risk Assessment: A Case Study of the Waters off Taiwan’s West Coast

This research examines the risk of natural disasters for offshore wind turbines together with their potential wind energy capacity to help the site selection of offshore wind power farms. Through evaluations of expert questionnaires, we use the fuzzy analytic hierarchy process to weight how natural disasters damage the sub-assemblies of an offshore wind turbine, then obtain the natural disaster risk assessment model, and finally utilize ArcGIS Pro 3.2 to map the potential wind farm sites for the waters off Taiwan’s west coast. We identify that typhoons are the most threatening type of disaster to generators, rotor blades, and rotor hubs; earthquakes are the most threatening to towers; and lightning is the most threatening to transformers. For the whole wind turbine, wind is ironically the most threatening natural disaster, followed by lightning, sea waves, and then earthquakes. Lastly, we examine the results by overlapping the offshore wind farms developed and planned in Taiwan, which coincide with locations in relatively low risk and high wind speed areas.

Coupled cluster method tailored with quantum computing

Introducing an active space approximation is inevitable for the quantum computations of chemical systems. However, this approximation ignores the electron correlations related to nonactive orbitals. Here, we propose a computational method for correcting quantum computing results using a well-established classical theory called coupled cluster theory. Our approach efficiently extracts the quantum state from a quantum device by computational basis tomography. The extracted expansion coefficients of the quantum state are embedded into the coupled cluster ansatz within the framework of the tailored coupled cluster method. We demonstrate the performance of our method by verifying the potential energy curves of LiH, H2O, and N2 with a correlation-energy correction scheme. Our method demonstrates reasonable potential energy curves even when the standard coupled cluster fails. The sufficient numbers of measurements for tomography were also investigated. Furthermore, this method successfully estimated the activation energy of the Cope rearrangement reaction of 1,5-hexadiene together with perturbative triples correction. These demonstrations suggest that our approach has the potential for practical quantum chemical calculations using quantum computers. Published by the American Physical Society 2024

The characteristics of heat exchanger for local utilization of wastewater heat under different operating conditions

RELEVANCE. The authors research the local utilization of wastewater heat (in close proximity to the place of their formation) based on a heat exchanger. To select rational characteristics of the heat exchanger and correctly assess the potential energy effect, it is necessary to take into account the influence of the operating conditions of the device (duration of individual use of the shower, mass flow of heated and heating water, temperature of heated water at the inlet to the heat exchanger, temperature of the flow at the moment the device is turned on).THE PURPOSE. The purpose of the work is to research the dependence of the efficiency of wastewater heat utilization on the operating conditions of the heat exchanger and to identify the parameters that have the greatest impact on the effect of energy-saving measures.METHODS. Based on a verified mathematical model of the thermal operation of a recovery heat exchanger, the temperature distribution inside the flows of the heated and heating water in time is calculated (from the moment of switching on until reaching a stationary operating mode). Based on the data obtained (the temperature of the heated water at the outlet of the heat exchanger at each point in time), the absolute and relative heat savings are determined under various operating conditions.RESULTS. The influence of the non-stationary phase of the heat exchanger operation on its energy efficiency is considered. For a specific heat exchanger configuration, the time required for the device to reach a steady state of thermal operation is determined. It was revealed that the greatest influence on the relative and absolute savings of thermal energy is exerted by such operating conditions as mass flow and temperature of heated water at the entrance to the heat exchanger. The temperature of the flow at the initial moment of time has the least influence on the energy effect.CONCLUSION. The operating conditions that have the greatest impact on the effect of local wastewater heat recovery are determined. The need to take these conditions into account when designing a heat exchanger and choosing its optimal parameters has been confirmed.

The Intersection of Architectural Conservation and Energy Efficiency: A Case Study of Romanian Heritage Buildings

In Europe, it is estimated that 14% of existing buildings were built before 1919, whereas 26% were built before 1945. In Romania, about 31% of the buildings date from before 1961, contributing to the current stock of old buildings with historic and architectural value in the country. This paper illustrates the current state of buildings with historic and architectural value in Romania, alongside a case study of a representative administrative building in Câmpulung, Romania. The analysis of the Town Hall building in Câmpulung, Romania, demonstrates that potential energy savings of up to 47.53% can be achieved by implementing interventions such as upgrading windows, insulating the attic, and installing photovoltaic panels. The highest energy reduction is obtained by replacing the window glass with a value of 18.16% with attic insulation with a value of 16.1%. This paper also presents indoor measurements of temperature and humidity in different offices positioned in the north and the south. The study conducted on the south façade office revealed consistent temperatures ranging from 21.7 °C to 24.4 °C, with an average of 23.31 °C. However, the humidity levels fluctuated considerably, ranging from 17.1% to 39.1%, with an average of 26.89%. The sun-exposed section of the building saw relatively stable temperature conditions, but the varying humidity levels could have a detrimental impact on the quality of the indoor atmosphere and potentially decrease the effectiveness of the workforce. By contrast, the north façade office exhibited lower and more fluctuating temperatures, ranging from 19.8 °C to 23.6 °C, with an average of 21.74 °C. Additionally, it had higher and more stable humidity levels, ranging between 19.5% and 41.7%, with an average of 29.83%. A thermographic analysis was performed on the north façade of the Câmpulung Town Hall, utilizing thermal imaging technology to detect areas of heat loss, and thus identifying the energy inefficiency problems of the building’s exterior. The investigation found notable variations in temperature, especially around the windows, where temperatures could be as high as 14.1 °C, highlighting the insufficiency of the building’s antiquated timber-framed windows in preventing energy loss.

Regularized relativistic corrections for polyelectronic and polyatomic systems with explicitly correlated Gaussians.

Drachmann's regularization approach is implemented for floating explicitly correlated Gaussians (fECGs) and molecular systems. Earlier applications of drachmannized relativistic corrections for molecular systems were hindered due to the unknown analytic matrix elements of 1/rix1/rjy-type operators with fECGs. In the present work, one of the 1/r factors is approximated by a linear combination of Gaussians, which results in calculable integrals. The numerical approach is found to be precise and robust over a range of molecular systems and nuclear configurations, and thus, it opens the route toward an automated evaluation of high-precision relativistic corrections over potential energy surfaces of polyatomic systems. Furthermore, the newly developed integration approach makes it possible to construct the matrix representation of the square of the electronic Hamiltonian relevant for energy lower-bound as well as time-dependent computations of molecular systems with a flexible and high-precision fECG basis representation.

Conformational Stability and Vibrational Relaxation as a Function of Halogen Substitution in Benzene sulfonamides: A Theoretical Study

AbstractStudying the vibrational energy flow within molecules can help us better understand their reactivity and facilitate the design of novel functional groups for potential drug candidates. This study examined the conformation of benzene sulfonamide in solvents and vacuum. Potential energy surfaces were computed for the two possible conformations, showing that the conformers’ stability varied with the medium. Additionally, the vibrational energy redistribution of halogen‐substituted benzene sulfonamide conformers was studied in solvents and vacuums. The lifetimes of the halogen stretching mode C−X (where X=F, Cl, or Br) in the substituted benzene sulfonamides were calculated and compared. The solvent and vacuum media lifetimes followed the order: C−Cl>C−Br>C−F. However, the degree of delocalization of vibrational energy was found to vary between them.

Engraved complementary toroidal metasurfaces for potential energy harvesting applications in microwave band

In the current study, complementary metasurface units with toroidal geometry were fabricated, using the computer numerical control engraving method. The metasurfaces were engraved in copper-coated, FR-4 plates. The produced metasurfaces were electromagnetically characterized in the microwave regime. Furthermore, they were studied regarding their energy harvesting capability, in the microwave range, where they absorb electromagnetic energy. It was found that toroidal structures harvest energy from the incident microwaves and transform it to electric power, through a simple rectification circuit. Moreover, their energy harvesting efficiency was found to be comparable or even superior to those of others reported so far. Therefore, the hereby obtained experimental results evidently show that engraved toroidal metasurfaces could potentially be used as energy harvesters in the microwave regime.

Numerical Study on the Performance of an OWC under Breaking and Non-Breaking Waves

A numerical model for the simulation of the performance of an oscillating water column (OWC) subjected to non-breaking and breaking waves is proposed in this paper. The numerical model consists of a hydrodynamic model specifically designed to simulate breaking waves and a pneumatic model that takes into account the air compressibility. The proposed numerical model was applied to evaluate the potential mean annual energy production from the waves of two coastal sites characterized by different hydrodynamic conditions: a deep-water condition, where the OWC interacts with non-breaking waves, and a shallow-water condition, where the OWC is subjected to breaking waves. The numerical results show that the effects of the air compressibility can be considered negligible only in numerical simulations of the performances of reduced-scale OWC devices, such as those used in laboratory experiments. We demonstrated that in real-scale simulations, the effect of the air compressibility within the OWC chamber significantly reduces its ability to extract energy from waves. The numerical results show that the effect of the air compressibility is even more significant in the case of a real-scale OWC located in the surf zone, where it interacts with breaking waves.

A Modified Crank-Nicolson Method for Numerical Solution of the Linear Time-Dependent Schrodinger Equation

This paper presents the effectiveness of the solution of the time-dependent Schrodinger equation using the modified Crank-Nicolson Method (MCNM). The method was developed through finite difference approximation. To demonstrate the effectiveness of this approach, three different problems were tested with these approaches by using MATLAB soft code. Also, this research verifies that, in the presence or absence of potential energy, the modified Crank-Nicolson method for solving the time-dependent Schrödinger equation is accurate, convergent, and computationally efficient.

Study of energy transfer and stress wave propagation during SPT through energy measurement and PIV

The blow counts in standard penetration tests (SPT) require suitable corrections to account for energy losses. Over 4,000 energy measurement data collected from four test sites across Hong Kong have been collected and analysed in this study. On average for all instrumented hammer blows, approximately 62% of the theoretical hammer potential energy is transferred to the drill rod assembly. Using high-speed camera imagery and particle image velocimetry (PIV), the detailed mechanism of stress wave propagation has been visualised and assessed. This has revealed new details and allowed nuances in the results of routine energy measurements to be interpreted in new light. It has been confirmed that the initial compressive wave is reflected as a tensile wave for low end-restraint at the SPT sampler and as a second compressive wave for high end-restraint. The commonly observed discrepancy between the theoretical and measured speeds of wave propagation is highlighted and explored. Energy loss arises from friction during free-fall of the hammer, at the anvil, and from other sources such as the horizontal motion of the hammer-anvil system. The proportion of each major source of energy loss is quantified.