Transfer Problem Research Articles

Application of a boundary-type algorithm to the inverse problems of convective heat and mass transfer

The inverse problems of the convection-diffusion equation (ICDE) have received extensive attention in incomplete boundary conditions and uncertain source terms. They can be applied in thermally stratified pipe elbows and so on. Many algorithms need to combine with optimization algorithms to repeatedly calculate the direct problem in the solution process. To solve such problems, this paper employs a boundary-type algorithm named the half-boundary method (HBM). The HBM does not require additional repeated optimization of the direct problem. To test the performance of the method, the numerical simulations of some problems have been carried out, including the inverse problems of heat convection, river pollution and air pollution. The results show that the HBM has the desired accuracy by comparing with the exact solution. If there are errors in the measurement process, the solution doesn't generate a large deviation from the result. It is worth noting that the placement of internal measurement points minimally impacts the numerical results within the solution domain. And the method is also able to handle with discontinuous problems. Because the Gaussian plume model verifies the accuracy of HBM, the HBM can quickly calculate the atmospheric diffusion of the non-Gaussian plume model.

Exploring Latent Transferability of feature components

Feature disentanglement techniques have been widely employed to extract transferable (domain-invariant) features from non-transferable (domain-specific) features in Unsupervised Domain Adaptation (UDA). However, due to the complex interplay among high-dimensional features, the separated “non-transferable” features may still be partially informative. Suppressing or disregarding them, as commonly employed in previous methods, can overlook the inherent transferability. In this work, we introduce two concepts: Partially Transferable Class Features and Partially Transferable Domain Features (PTCF and PTDF), and propose a succinct feature disentanglement technique. Different with prior works, we don’t seek to thoroughly peel off the non-transferable features, as it is challenging practically. Instead, we take the two-stage strategy consisting of rough feature disentanglement and dynamic adjustment. We name our model as ELT because it can systematically Explore Latent Transferability of feature components. ELT can automatically evaluate the transferability of internal feature components, dynamically giving more attention to features with high transferability and less to features with low transferability, effectively solving the problem of negative transfer. Extensive experimental results have proved its efficiency. The code and supplementary file will be available at https://github.com/njtjmc/ELT.

Heat transfer from a cylindrical heater to a medium with variable thermophysical characteristics and heat source power

The formulation and solution of the problem of non-stationary thermal conductivity in a composite material with variable thermophysical characteristics are considered. Density, heat capacity, thermal conductivity, as well as the power of the heat source due to the hydration reactions of the binder components change during the concrete hardening process. The heat transfer problem is formulated for the general case when there are no calculation formulas for thermophysical transfer coefficients. The “microprocess method” was used to calculate the dynamics of the temperature field. According to this method, the space from the outer surface of the heater is modeled by a system of successively located “rings”. When moving from the previous “ring” to the next one, the charge in the transfer coefficients and the power of the volumetric heat source were taken into account. At the same time, the initial and boundary conditions were corrected. The boundary value problems are formulated in the form of a differential equation of non-stationary heat transfer with an arbitrary initial distribution of transfer potentials, Dirichlet boundary conditions, and a heat source in the form Po=f(Fo).The obtained solutions are analyzed for some particular cases. Prospects for further theoretical and experimental research are determined.

Achieving High Performance with Less Energy Consumption: Intermittent Ultrasonic-Mediated Operation Mode for Fe/V Non-Aqueous Redox Flow Battery

Deep eutectic solvents (DESs) have attracted much attention as sustainable electrolytes for redox flow batteries. Despite the tremendous advantages of DES-based electrolytes, their high viscosity property has a negative effect on their mass transfer, limiting current density and power density. The ultrasonic effect has been demonstrated as an efficient strategy to improve mass transfer characteristics. Incorporating ultrasonic waves into a deep eutectic solvent (DES) electrolyte enhances the mobility of redox-active ions, thereby accelerating the reaction dynamics of the Fe(III)/Fe(II) redox pair. This enhancement makes it suitable for use in non-aqueous electrolyte-based redox flow batteries. However, it is necessary to consider the loss of ultrasonic on the internal structure of the battery, as well as the loss of battery component materials and ultrasonic energy consumption in practical applications. Moreover, the continuous extension of the duration of ultrasonic action not only hardly leads to a more significant improvement of the battery performance, but is also detrimental to the energy and economic savings. Herein, intermittent ultrasound is used to overcome the quality transfer problem and reduce the operating cost. Good electrochemical performance enhancement is maintained with a roughly 50% reduction in energy consumption values. The mechanism as well as the visualization of the pulsed ultrasonic field on each half cell has been envisaged through fundamental characterization. Finally, the feasibility of interrupted ultrasonic activation applied to Fe/V RFB using DES electrolytes has been demonstrated, demonstrating similar behavior with continuous ultrasonic operation. Therefore, the interrupted ultrasonic field has been found to be a more effective operation mode in terms of energy cost, avoiding alternative undesirable effects like overheating or corrosion of materials.

A Semi-implicit Stochastic Multiscale Method for Radiative Heat Transfer Problem in Composite Materials

A Semi-implicit Stochastic Multiscale Method for Radiative Heat Transfer Problem in Composite Materials

The Negative Transfer of Dialects on Primary School Students' English Phonetics Acquisition and Its Teaching Implications-Taking Kunming Dialect as an Example

Abstract: In the process of learning a second language, correct pronunciation is an indispensable prerequisite for having strong listening and speaking skills. Primary school students in Kunming (represented by the urban area) often experience negative phonological transfer in the process of English phonological acquisition due to their habitual use of dialects, resulting in inaccurate pronunciation and weak listening and speaking skills. Based on the information from three aspectsteaching experience, literature reading and internet search, this paper summarizes the common negative phonological transfer problems of primary school students, such as mispronouncing the vowel [a] sound as [e] sound, having difficulty in effectively distinguishing between consonant [v] sound and [w] sound, and being very prone to confusing basic long and short sounds. The above problems can be solved by strengthening teacher training, optimizing teaching strategies and introducing educational resources. Such measures can significantly aid students in improving their pronunciation accuracy, thereby laying a solid foundation for better listening and speaking skills.

Temperature Distribution in a Two-Scale Porous Structure of a Catalyst Made of Spherical Particles

The research deals with the determination of the temperature distribution in a two-stage porous catalytic medium when the heat flow passes through. The peculiarity of the proposed model of heat and mass transfer in a porous catalyst is to consider the change in the volume of the spherical particle that makes up the catalyst.A program for calculating the temperature distribution in a two-scale porous structure of a catalyst made of spherical particles that change in volume with time has been developed. It should be noted that the temperature gradient is rather high, and the temperature in the central region of the particle becomes high enough for the process of catalytic reaction initiation only after 3.25 s. The developed program together with analytical and empirical studies allow to find the range of temperature and time of heat treatment at which the given thermophysical characteristics of porous material will be observed.The work will be useful for engineers and scientists studying the problems of thermochemical reactors and heat transfer in catalytic fills.

A Physics Informed Neural Network for Solving the Inverse Heat Transfer Problem in Gas Turbine Rotating Cavities

Abstract Recently, Physics-Informed Neural Networks have displayed great potential in delivering swift and accurate solutions for inverse problems. Here, a Physics-Informed Neural Network (PINN) was used to solve the inverse heat conduction problem in the rotating cavities of a aeroengine high-pressure compressor internal air system. The neural network was designed to receive experimentally captured radially distributed temperature profiles as inputs and predict the associated surface heat fluxes. The correctness of these predicted heat fluxes are assessed by numerically solving the direct heat conduction equation using a 2D Finite-Element model, thereby recovering the original temperature profiles. A comparative analysis is conducted between the predicted temperature profiles and the initial inputs. The physics informed neural network is trained using noise free synthetic data, created from a range of radial temperature curve fit coefficients, and subsequently tested on noisy experimental data at engine representative conditions. The predicted temperature values exhibit some good agreement with their respective actual counterparts. Furthermore, the sensitivity of model hyperparameters are explored to showcase the capability of the proposed approach. The results show that Physics- Informed Neural Networks exhibit reduced susceptibility to experimental uncertainties when addressing inverse problems, in contrast to inverse solution methods, and offer a possible new approach for analysis of experimental data if trained on a sufficiently large dataset.

Modeling and analysis of fluid-solid coupling heat transfer and fluid flow in transonic nozzle

Solid rocket motors (SRMs) are the power units of modern aerospace transportation, and it is of great significance to predict their flow and heat transfer characteristics by numerical simulation. This numerical study is based on a self-developed code framework MHT (Multi-X Heat Transfer, where X represents the region, scale, physical field, and other aspects) and presents an effective method of analyzing fluid–solid coupling heat transfer problem in an axisymmetric supersonic nozzle. For the nozzle wall heat conduction and nozzle-in fluid flow there are two kinds of solution methods, the detached (solved separately in solid and fluid region and them coupling at the interface) and the whole field method (solve the conduction and convection simultaneously). The whole field method is more efficient but few scholars use it to solve the nozzle coupled problem. This paper introduces the numerical details of the whole field solution method, and provides a new idea for the coupling solution of the nozzle. In addition, a mixed grid system is proposed around the interface region of fluid and solid, in which the quadrilateral structured mesh is used at the fluid side, and the triangular unstructured mesh is used for the outer fluid region and the whole solid region to ensure the accuracy of the 1st-oder normal derivatives calculation. The self-developed code is validated by comparison with well-known commercial soft-ware. Transient results of temperature and velocity are presented for the instants of 1st 10 s and 20 s of a practical nozzle.

MFWOA: Multifactorial Whale Optimization Algorithm

Multi-task optimization is an emerging research topic in the field of evolutionary computation, which can exploit the synergy between tasks to solve multiple optimization problems simultaneously and efficiently. However, the correlation and negative transfer problems between tasks are the main challenges faced by multi-task optimization. To this end, this paper proposes a new multi-task optimization algorithm, named Multifactorial Whale Optimization Algorithm (MFWOA). MFWOA uses the Whale Optimization Algorithm (WOA) as a search mechanism and designs an adaptive knowledge transfer strategy to effectively exploit the correlation between tasks. This strategy includes two ways: one is to exchange search experience by adding distance terms from other tasks; the other is to generate new random individuals or optimal individuals through crossover and mutation operations and use them to guide position updates. By combining these two methods, MFWOA can explore a wider area. In addition, in order to better balance the useful information transfer between and within tasks, MFWOA also designs a random mating probability parameter adaptive strategy. Experimental results show that MFWOA can achieve effective and efficient knowledge transfer, and outperforms other multi-task optimization algorithms in terms of convergence speed and accuracy. It is a promising multi-task optimization algorithm.

Analysis of convection and boil-off in multi-scale membrane LNG tanks under sloshing excitations

The marine storage and transportation of liquefied natural gas (LNG) in membrane tanks involves complex thermodynamic responses, significantly affecting system operation reliability. The study investigates the coupled problem of heat transfer and sloshing in LNG tanks through small-scale experiments and simulations. A tank partially filled with R134a was analyzed under various non-isothermal sloshing excitations to examine the free surface, flow, and heat transfer. Changes in fluid temperature, wall temperature, and heat flux were measured under different sloshing frequencies, amplitudes, and filling levels. A Computational Fluid Dynamics (CFD) analysis was performed, considering heat flow in the insulation layer and phase changes in the membrane tank. The tank was assumed to be vented. A Volume-of-Fluid (VOF) model with a dynamic mesh provided insights into the effects of sloshing on heat transfer and flow. Model feasibility was confirmed by comparing simulation results with fluid sloshing experiments. An extended sloshing Nusselt number was calculated, and a correlation formula related to sloshing conditions was developed, allowing for a quantitative assessment of enhanced heat transfer. Simulations explored evaporation characteristics in various scales of LNG tanks under static and sloshing conditions. The results showed that the evaporation rate of LNG increases as the tank scale decreases, with sloshing significantly impacting LNG storage and transportation. The study enhances the understanding of heat transfer and flow evolution in LNG tanks, improving the accuracy of evaporation models and providing insights for optimizing tank design and operation under sloshing conditions.

Recognition of palaeo-glacial troughs with cirques on parts of Tibetan Plateau using multi-modal datasets with deep learning models

Recognition of landforms associated with past glaciation is crucial for understanding past ice dynamics and their relationship to climate. With the development of artificial intelligence technology, deep learning techniques have assisted in the automatic extraction of glacial landforms, but these methods still face problems of low precision and weak transferability. This study proposes a new method named geomorphology-attention DeeplabV3+ (GA-DeeplabV3+) model. This method adds spatial attention and channel attention modules based on the DeeplabV3+ network and utilizes a combination of multi-modal geographic data. Verification shows that the model proposed in this paper significantly enhances the recognition precision of glacial troughs with cirques compared to existing models, reaching a Mean Intersection over Union (MIoU) of 86.2% and a mean Pixel Accuracy (mPA) of 90.64% in the area of the Palaeo-Daocheng ice cap. In addition, validation experiments were conducted in the Peiku Gangri region and the Tenasserim mountains, achieving MIoU scores of 70.09% and 73.28% respectively. This accomplishment represents a vital stride towards automating the extraction of palaeo-glacial landforms, which holds great significance for analyzing the scale and evolution of ancient glaciers.

Thermal stress in externally irradiated tubes of solar central receivers with a gas–particle fluidized dense suspension

One of the objectives of the new generation of concentrating solar power plants is to increase the actual temperature limit (565 °C) up to or near 1000 °C. An alternative heat transfer fluid that could help to reach this objective is the use of a fluidized dense gas–particle suspension ascending through a vertical tube. Since the predominant cause of rupture in solar receivers is the creep-fatigue damage process, which is mostly influenced by the maximum temperatures and stress experienced along the tube, the main objective of this work is to numerically study the thermomechanical behavior of a non-uniform externally irradiated tube where particles are fluidized and moves upwards. The heat transfer problem in the two media present (i.e. dense suspension of particles and tube wall) was solved separately: a Computational Particles Fluid Dynamic model solves the heat transfer in the particles, whereas a three dimensional Finite Volume model simulates the heat conduction through the tube wall to obtain the temperature profile, which serves as input to calculate the thermal stress of the tube with an analytical method. Higher thermal stresses were obtained for an absorbed power of 250 kW/m2 (σVM,max=219MPa) compared to that for an absorbed power of 500 kW/m2 (σVM,max=72MPa) due to the lower temperature difference between the front and rear sides of the tube caused by the more pronounced increase of the radiative losses in the front side of the tube compared to that at the rear side. The thermomechanical behavior of a particle receiver was compared to that of a molten salt receiver. For an incident solar flux of 500 kW/m2, the particle receiver reduced the maximum thermal stress by 73% compared to the molten salt receiver. However, the tube’s maximum temperature exceeded the working limit for stainless steel tubes. In order for the receiver to survive heat fluxes characteristic of solar power plants, research into technological solutions that allow to improve the effectiveness of the heat transfer rate from the tube to the particle flow is necessary.

P2P transfers: modern characteristics in the context of prevention and anti-laundering (laundering) of income obtained by criminal ways

Problem setting. Nowadays, P2P (peer-to-peer) card-to-card transfers have become an integral part of our daily lives. It is a convenient way to transfer money quickly and securely without intermediaries, bank queues or complicated procedures. Thanks to modern technology such transfers are made in seconds via mobile applications, internet banking or specialised services ensuring maximum speed and simplicity of financial transactions. P2P transfers open up new opportunities for people to interact with each other making financial services more accessible, convenient and low-cost. But at the same time, such payments should be characterized by secure use and transparency which are two of the most important features for those who often first encounter the world of financial services through these solutions. Purpose of research is to define the concept of P2P payment, analyze the advantages and debatable aspects of this kind from the point of view of ensuring financial security, combating money laundering. Аnalysis of recent researches and publications. Scientists, economists and lawyers, contributed to the study of the problems of money transfers, combating the legalization (laundering) of proceeds obtained through crime, digital innovations in the field of money circulation and calculations: O. Decyk, E. Golovei, V. Stalirov, O. Prokoposhina ., Pylypenko P.M., Mallory M., Klochko A.M., Volchenko N.V., Dmytryk O.O., Maryniv N.A., Parashchenko O.K., Ovcharenko A.S. etc. At the same time, the indicated topic does not lose its relevance and needs further consideration. Аrticle’s main body. Іn this article we will look at the main advantages and disadvantages, the possibilities of P2P transfers, their impact on the development of financial technologies as well as the security nuances that should be taken into account when conducting such transactions. The article is focused on the decision of the National Bank of Ukraine on card restrictions on transfers between individuals this restriction is based on the decision of the National Security and Defence Council of Ukraine to combat illegal gambling but in fact the goal is much broader, including countering hidden business profits and unofficial wages as well as combating financial fraud known as money laundering. It is analysed that the legal regulations to create a safe environment for financial institutions to conduct transactions and reduce unsafe money mulesing transfers. The article is provided a detailed analysis of the phenomenon of financial mulling which is the illegal transfer or movement of funds through intermediaries used for criminal activities. The authores analyses that the main mechanisms of involvement of individuals in this process the ways in which criminal groups use financial mules for money laundering as well as the risks and legal consequences for those who become involved in such schemes, including international experience of bringing to criminal responsibility. It also examined the legal regulators and tools to create a secure environment for financial institutions to conduct transactions. Сonclusions and prospects for the development. P2P payments represent an important digital technological innovation in the field of money circulation, which provides users with the ability to make transfers directly, without the involvement of intermediaries such as banks or payment systems. However, along with advantages such as speed and convenience, there are significant risks associated with the security of such operations. At the same time, one of the key vulnerabilities of P2P payments is the risk of their use for money laundering through the "money muling" mechanism. Such methods not only contribute to the spread of financial crimes, but also create a threat to the financial system of the state as a whole. Despite the implementation of protection mechanisms, which include identification of users using biometric data, monitoring of transactions, implementation of KYC and compliance with the AML regulatory framework, the issue of money laundering remains relevant. This emphasizes the need for further scientific research in the field of security of P2P payments, in particular: regarding the development of more advanced innovative technologies for the detection and prevention of money laundering schemes, the implementation and improvement of legal regulation of these topics, as well as the establishment of liability for such an offense as "money laundering".

Asymptotic Solution of the Problem of Convective-Diffusive Transfer of Sorbable Water-Soluble Compounds in Dispersed Media with Regard to the Kinetics of Sorption and Diffusion in the Pore Solution

Asymptotic Solution of the Problem of Convective-Diffusive Transfer of Sorbable Water-Soluble Compounds in Dispersed Media with Regard to the Kinetics of Sorption and Diffusion in the Pore Solution

Assessment of Multigrid Schemes with Fixed Patterns for a Two-Dimensional Heat Transfer Problem

Heat transfer problems and their solutions are of critical importance in almost all areas of engineering and technology, while many real-world problems are inherently three-dimensional. Simplifying them to 2D models offers practical advantages with reasonable models. With being the fundamental class of problem of heat transfer, the 2D thermal diffusion problem was selected for the study. Multigrid methods were referred to as standing out in terms of cost reduction while keeping solution accuracy. The effectiveness of multigrid methods employing fixed pattern schemes was subject to investigation. To set up numerical experimentation, an authentic code generation effort was given that implements a basic finite volume method, intergrid operations and iterative solvers. A reference case with an analytical Laplace solution was selected and properly validated by the results. A variety of multigrid schemes with fixed patterns were explored around parameters, iterations per sweep and maximum coarsening level. Results were compiled on the focal points of cost and performance. A comparison of the direct iterative methods with multigrid schemes proved the effectiveness of multigrid schemes. With the assessment of the cost and performance outcomes, it is concluded that any multigrid scheme should visit the maximum coarsest level possible while keeping a minimum number of iterations on each grid resolution.

Translation of catch phrases in an audiovisual text

The article discusses the problem of interlinguistic and intercultural transfer of winged words (catch phrases) in an audiovisual text of the Soviet period. The source of the material is the Russian motion picture "Moscow Does Not Believe in Tears" and its translation into English (subtitling), the material is 34 winged words (catch phrases) which were selected with verification based on Internet sources. The purpose of the research is to study the methods/techniques of transferring catch phrases in audiovisual translation (subtitling) from Russian into English, as well as to analyze the results obtained from the point of view of preserving the characteristics inherent in catch phrases and preserving the national cultural component. The main methods are the method of continuous sampling, the method of comparative analysis, the method of contextual analysis, etc. The direction of the translation (Russian-English translation) and the approach chosen by the authors indicate the novelty of the research. Having analyzed the translation of catch phrases, the authors made observations regarding the methods/techniques used which contributed to conveying meaning and complying with the norms of audiovisual translation, as well as to the conclusions that a partial loss of cultural information may occur during translation and that in a situation where a film subsequently becomes a precedent text, postediting may be required, as the conditions of how the text/part of the text functions in the linguoculture of the original language change. The results may be of interest to specialists in the field of audiovisual translation, as well as to philologists, linguists, and to ordinary readers who are interested in translation studies and/or cinematography.

Achieving excellent thermal transport in diamond/Cu composites by breaking bonding strength-heat transfer trade-off dilemma at the interface

The heat transport enhancement of diamond/Cu composites, a new generation of thermal management materials, is trapped in the bonding strength-heat transfer trade-off dilemma at the interface due to the noticeable difference in physical and chemical properties between Cu and diamond. Herein, we propose a new strategy combining ultrathin interface modification and low-temperature high-pressure (LTHP) sintering process to prepare the diamond/Cu composites. With a suitable coefficient of thermal expansion (CTE) of <10 ppm/K, the obtained diamond/Cu composites exhibit an outstanding thermal conductivity (k) value of 763 W/m K, over 90 % of the theoretical prediction of the differential effective medium (DEM) model. Meanwhile, using a lower diamond volume fraction (45 % vs. 50%–70 %), the k value is higher than those by conventional powder metallurgy, meaning a substantial reduction in the cost by reducing diamond filler content. For such a highly mismatched diamond/Cu interface, we maintain a high bonding strength by lowering the thermal stress damage while achieve a high thermal conductance (G) of 93.5 MW/m2 K by minimizing the heat transfer obstacles. The prepared interface structure is a diamond/TiC/CuTi2/Cu configuration, where the two possible heat transfer bottlenecks (the diamond/TiC interface and the TiC/CuTi2 interlayer) are no longer limiting factors on the overall interface. The successful resolution to the interfacial heat transfer problem is responsible for the superior thermal transport performance of the composites. This work deals with the critical challenge for the diamond/Cu composites and offers deep insight into the improvement mechanisms of thermal transfer. The proposed strategy can be generalized to the integration of highly mismatched interfaces widely present in other composites or thermal management systems.

A Critical Assessment of the Process and Logic Behind Fish Production in Marine Recirculating Aquaculture Systems

A recirculating aquaculture system (RAS) represents a forward-looking form of aquaculture. A RAS consists of fish tanks and water treatment processes in a closed loop to sustain the environmental conditions for fish production. However, the rapid industrialization of the technology is fraught with transfer problems. This review justifies a RAS process chain based on fish biology. The underlying concept has been evaluated by the author in experimental and commercial RAS projects. The core idea is that the fish must be considered as a technical subcomponent in a RAS, determining the technology. Fish, when considered as small biological machines, are still a black box in many ways. However, their basic biology and physiology provide all the knowledge to implement them in a technical setting. The information required to understand this concept is presented and discussed based on current scientific knowledge. The conclusion is that the technology is available but needs to be rigorously implemented. If this were carried out, fish production in RASs would be ecologically sustainable, which is already claimed for RASs but is not always the reality in commercial applications.

A space-time meshfree method for heat transfer analysis in porous material

Abstract Porous material batteries are a new type of battery technology that uses porous materials as electrode materials, with advantages such as long lifespan. In the present study, we manily propose a space-time meshfree method for heat transfer problems in porous material energy storage battery. The thermal behavior is demonstrated based on a numerical solution of the energy conservation equation. A simple space-time meshless collocation scheme, which is based on a new type space-time radial basis function, is presented to get the approximate solution of the energy conservation equation. The energy conservation equation was transferred into a system of linear algebraic equations. By introducing prescribed boundary conditions, the heat transfer analysis in porous material energy storage battery can be shown with numerical results. Numerical discussions show that the proposed meshless collocation method is appropriate to simulate thermal behavior in porous material energy storage battery, while the traditional finite element method failed to provide the reasonable results for the tested examples in this paper.