Linear Distribution Research Articles

Design and optimization of gradient fibrous media using the method of moments

The goal of this work is to optimize the deposition mass distribution of polydisperse particles inside the fibrous media by modifying the distribution of the fiber packing density across filter depth. Two types of gradient fibrous media with linear and exponential fiber packing density distribution along the flow direction were derived. The method of moments was employed to study the transport and deposition characteristics of polydisperse aerosol particles inside the fibrous media. The reliability of the calculated results by the method of moments was confirmed by the numerical simulations based on the discrete phase model (DPM). Results indicate that the gradient fibrous media allows more particles to transport and deposit into the interior of the fibrous media, which improves the uniformity of particle deposition distribution across filter depth. There exists an optimal fiber packing density distribution ratio for the gradient fibrous media where the non-uniformity of deposition mass distribution of polydisperse particles across filter depth is minimized. In this way, uniform deposition distribution along the flow direction can be generally achieved by optimizing the fiber packing density distribution, which will contribute to the optimal design of microstructures for the fibrous filter.

Transferable machine learning model for the aerodynamic prediction of swept wings

With their development, machine learning models can be used instead of computational fluid dynamics simulations to predict flow fields in aerodynamic optimization. However, it is difficult to construct a prediction model for swept wings with various planform geometries because too many samples are required to cover the parameter space. In the present paper, a new model framework is proposed to predict wing surface pressure and friction distributions with fewer samples. The distributed geometry parameters along spanwise are used as model inputs instead of the global planform parameters, and processors are designed to help the model better learn the local effect of geometric variation. The model is trained and tested on simple swept wings with single segment and linear twist distribution, where it outperforms the global input model by 57.6% in terms of lift coefficient prediction errors on small dataset sizes. The distributed input also enables the model to be transferred from single wings to more engineering-practical yet complex kink wings. After fine-tuning with a few samples, model accuracy for kink wings can be similar to that of simple wings, which proves the model for wings with complex planform geometries can be efficiently built with the proposed method.

Influence of inhomogeneous distribution of inflow equivalence ratio on oblique detonation morphology and characteristic

In this paper, numerical simulations using Euler equations coupled detailed chemical reaction model are performed to reveal the influence of inhomogeneous distribution of inflow equivalence ratio (ER) on the morphology and characteristic of oblique detonation in hydrogen/oxygen/argon mixtures. The purpose of this study is to better understand the key parameters’ variation law of oblique detonation flow field under practical flight conditions so as to guide the design of oblique detonation chamber. Within the scope of our simulations, the results show that the oblique detonation wave (ODW) can still be standing under a large ER gradient. The thermodynamic state and characteristic sizes of the flow field reach the maximum value around ER = 0.8. First, the ODW angle and the post-wave temperature/pressure increase with the homogeneous inflow ER. Then, the inhomogeneity of inflow ER is introduced by assuming a lateral linear distribution covering the whole inflow boundary. When the ER increases along the inflow boundary with ER = 0 at the wedge tip, the overall morphology of the ODW presents a concave structure. Inversely, the ODW is convex with ER = 0 at the top outlet. The morphology and characteristic sizes of ODW are determined by the mixture composition in front of the corresponding wave surface. The transition mode of ODW is mainly determined by the ER of the incoming flow in front of the induction region.

Маркування ведмедем (Ursus arctos) дерев у Чорнобильському біосферному заповіднику

For the first time in the Ukrainian Polissia and the Chornobyl Radiation and Ecological Biosphere Reserve (ChREBR), a concentrated linear distribution of bear-marked spruce trees was found at the abandoned estates of the village of Opachychi along the second terrace of the Prypiat River floodplain. Individual sightings of bears (Ursus arctos) in the Ukrainian Polissia have been known since the 1990s, but there are no reliable data on the reproduction of this species. The abundance of bears in Belarus has increased in recent years, which leads to the possibility of females coming to the Polissia from the north. Dried spruce trees without resin were not marked by the bear, and the animal moved on to live trees. Friction and more intensive marking of trees was recorded mainly in the eastern direction. Most of the marked spruce trees were upright with no branches to the height of the marking. The intensive marking behaviour of bears in 2023 in the ChREBR can be considered as the appearance of a female, as signalling to a female, and as a sign of dominance towards a male competitor. Two adult males were observed near one of the marked trees (data from amateurs). Special field surveys are needed to identify females with cubs to confirm or refute the hypothesis that the intensity of bear marking can be used in the event of the presence of a female bear in oestrus. Along the bear-marked trees in the village of Opachychi of the ChPEBR, an ecological trail and a visitor centre of large carnivores and herbivores should be created, which would be popular destinations. It is advisable to arrange a location for wildlife observations in an abandoned house for photo and video shooting, as is usually done in Sweden, Bulgaria, Romania, and Spain. In such tours, the effectiveness of the observation is not guaranteed and only preliminary statistics of wildlife encounters are provided. For this purpose, it is advisable to create two feeding areas for predatory mammals with dry food, as well as a salt marsh and a feeding trough for ungulates. The majority of the ChREBR territory has a low incidence of markings. The bear in the Polissia, as elsewhere in Europe, is expanding its range naturally, but at a slow pace due to the low intensity of female dispersal. Tree marking by bears was also observed in Chernihiv Oblast, in the Mizhrichynskyi Regional Landscape Park. It is advisable to release several bears in the ChEBR to create a reproductive centre for this species in the Polissia.

A study on the prediction of service reliability of wireless telecommunication system via distribution regression

The reliability of wireless telecommunication service has become a major concern for the operation and maintenance (O&M) departments of the major telecommunication service providers. Consequently, reliability prediction has assumed a pivotal role for O&M department to furnish dependable services while simultaneously curtailing operational costs. However, predicting the service reliability is a challenging issue mainly attribute to the mobility characteristics of the end-users in the network. In tandem with the formulation of service reliability metrics, this study introduces a linear distribution regression model under Gaussian distribution and a kernel-based distribution regression model tailored for bimodal scenarios. The empirical validation of these proposed metrics and methodologies is substantiated through case studies employing both simulated data and real-world datasets derived from a wireless telecommunication system within an urban district. The outcomes of these case studies demonstrate the efficacy and applicability of the proposed metrics and methods.

Effects of porosity and porosity distribution in gas diffusion layer on the performances of proton exchange membrane fuel cell

The transmission capability of the gas diffusion layer directly impacts electrochemical reaction and water drainage, consequently, the comprehensive performance and lifetime of the proton exchange membrane fuel cell. The gas diffusion layer's porosity and distribution must be designed effectively as a porous component. This study focuses on experimentally validated models to investigate the effects of porosity and distribution in the gas diffusion layer using three-dimensional numerical simulation. A porosity of 0.6, with a unitary distribution, provides comprehensive improvements in power density while minimizing pressure drops. Additionally, four different distribution patterns of porosity (28 cases) are studied while maintaining an overall porosity of 0.6. The linear porosity distribution (along the flow path) with positive slopes outperforms the alternant distribution due to the cumulative effects on the micro-subsection of the gas diffusion layer. The stepped and/or the sinusoidal distribution can also improve the performances, but just when the step gradient and/or the amplitude are sufficiently small. The adverse effects on the uniformity of current density cause the sinusoidal distribution to be inferior to linear and stepped distribution patterns. The transmission of oxygen significantly affects the dynamic performances, with the distribution patterns of porosity critically influencing sensitivity.

Diamond energy-dispersive dosimeter for measuring linear energy deposition distributions in clinical carbon beam therapy

A thin diamond membrane energy-dispersive dosimeter 50 μm thick was fabricated for estimating clinical dose distribution. In contrast to conventional semiconductors, diamond wide-bandgap semiconductors are expected to have excellent radiation tolerance and biological compatibility based on the linear relationship of stopping power ratio for clinical carbon particles. Linear energy transfer (LET) spectra were obtained along with the Bragg curve for a clinical carbon beam generated at Gunma University Heavy Ion Medical Center. The relative biological effectiveness (RBE) distributions were estimated from the LET spectra for both the mono-energy and spread-out Bragg peak irradiation configurations. The diamond detector was also used as a solid ionization chamber to obtain the radiation-induced current (RIC) distribution, which represents the physical dose distribution. The clinical dose distribution was estimated from the RIC and RBE distributions as proof of concept for the clinical carbon beam therapy field with a single-chip diamond energy-dispersive dosimeter.

A method for estimating optimized porosity distribution in Reaction-Diffusion systems without reliance on topology optimization

Topology optimization is a powerful method for designing optimal structures within a given design domain, applicable not only to physical systems but also to systems involving chemical reactions. This study employs entropy generation analysis in nonequilibrium thermodynamics as a metric to evaluate optimization results in conjunction with topology optimization. To enhance our understanding of the relationship between topology optimization and entropy generation analysis, exact solutions were derived in a simple 0D case. Nevertheless, solving the partial differential equations associated with topology optimization can be computationally intensive and time-consuming. This study proposed an alternative approach that bypassed the need for optimization methods by introducing reasonable assumptions, thereby reducing the computational effort required. By assuming a linear distribution of species concentration, the proposed approach yielded comparable performance to that achieved by optimization methods. This research contributes to streamlining the design process of electrochemical devices and reducing the computational burden associated with optimization.

Subsurface damage evolution of β-Ga2O3 (010) substrates during lapping and chemical mechanical polishing

For semiconductor single crystal substrates, subsurface damage (SSD) is an important factor for device failure. For β-Ga2O3 with two cleavage planes, the SSD is the key issue that needs to be addressed. In this work, β-Ga2O3 (010) substrates were lapped and polished precisely. The formation and evolution mechanisms of SSD were analyzed by cross-section transmission electron microscopy and wet chemical etching techniques. The linear distribution of scratches was found on the substrates after lapping. After chemical mechanical polishing (CMP), the surface scratches were eliminated. However, the SSD layer may still exist under the surface. Chemical etching was developed to identify the "invisible damage" to the CMP-finished (010) substrate. The SSD including nanocrystalline, tilt boundary, twist boundary, and high-density dislocations in β-Ga2O3 was first reported. Distinctively, there was no slip occurrence in the SSD of the (010) plane different from the (100) and (001) planes. The Schmid factor of multiple slip systems was calculated to analyze the cause of no slip on the subsurface. The formation mechanism of SSD was believed that when the slip system could not be activated, the stress was released through rotation and distortion of the crystal plane. The accumulation of grain boundary dislocations at twist grain boundary junctions provided a driving force for the formation of nanovoids. The relationship of substrate damage evolution and crystal strain with different machining parameters was established by high-resolution X-ray diffraction and Raman spectra. A non-damaging β-Ga2O3 (010) substrate with a surface roughness of less than 0.2 nm was obtained by the optimized CMP process. The research results had guiding significance for damage control of β-Ga2O3 and other brittle crystals in ultra-precision machining.

Advancing estimation techniques and their applications in engineering and medical data analysis through novel continuous and discrete linear failure rate distribution extension

In this paper, we present a new heavy-tailed distribution called the heavy-tailed linear failure rate (HTLFR) distribution. Various statistical properties of the proposed distribution are derived, including the quantile function, the median, the ordinary moments, the moment generating function, the incomplete moments and the conditional moments. Some actuarial measures such as value at risk, expected shortfall, tail value at risk, tail variance and tail variance premium are calculated. Three different methods of estimation such as the maximum likelihood method, the maximum product spacing method and the Bayesian method as well as some simulation results for the model parameters of the HTLFR distribution under complete samples are examined. The results of the real data set show that the proposed distribution has greater flexibility and has been empirically evaluated under complete data. Discrimination analysis was employed to ensure fairness, equity, and accuracy in decision-making processes for selecting the best model, comparing the proposed distribution with known distributions. A discrete analog of the HTLFR distribution is proposed.

Active aeroelastic flutter control of supersonic smart variable stiffness composite panels using layerwise models

This work focuses on the layerwise finite element modelling and active aeroelastic flutter control of smart variable stiffness laminated composite panels with surface bonded piezoelectric layers/patches under supersonic airflow. The proposed aero-electro-elastic models make use of the First- and Third-order Shear Deformation Theories, along with a linear through-thickness distribution of the electric potential, whereas the effect of the supersonic airflow is described by the First-order Piston Theory. Numerical applications of simply supported smart composite panels with either curvilinear or unidirectional fibres are provided for the accuracy assessment of the proposed models predictive capabilities, considering various side-to-thickness ratios and control conditions. The effect of proportional control on the aeroelastic flutter response is discussed for both airflow along the x-axis and yawed airflow, in addition to three different placement configurations of the piezoelectric patches.

The significance of quadratic thermal radiative scrutinization of a nanofluid flow across a microchannel with thermophoretic particle deposition effects

Abstract The investigation of thermal radiation and thermophoretic impacts on nano-based liquid circulation in a microchannel has a significant impact on the cooling of microscale equipment, microliquid devices, and many more. These miniature systems can benefit from the improved heat transfer efficiency made possible by the use of nanofluids, which are designed to consist of colloidal dispersion of nanoparticles in a carrier liquid. Understanding and precisely modeling the thermophoretic deposition (TPD) of nanoparticles on the channel surfaces is of utmost importance since it can greatly affect the heat transmission properties. This work examines the complex interaction between quadratic thermal radiation, magnetohydrodynamics, and TPD in a permeable microchannel. It aims to solve a significant knowledge gap in microfluidics and thermal and mass transport. The governing equations are simplified by applying suitable similarity restrictions, and computing solutions to the resulting equations is done using the Runge‒Kutta Fehlberg fourth‒fifth-order scheme. The results are shown using graphs, and significant engineering metrics are analyzed. The outcomes show that increased Eckert number, magnetic, and porous factors will improve the thermal distribution. Quadratic thermal radiation shows the greater thermal distribution in the presence of these parameters, while Linear thermal radiation shows the least thermal distribution. The rate of thermal distribution is higher in the linear thermal distribution case and least in the nonlinear thermal radiation case in the presence of radiation and solid fraction factors. The outcomes of the present research are helpful in improving the thermal performance in microscale devices, electronic devices cooling, health care equipment, and other microfluidic applications.

Employing generative adversarial neural networks as surrogate model for reactive transport modeling in the hyporheic zone

This study explores the application of advanced deep learning techniques, specifically conditional deep convolutional generative adversarial networks (cDC-GANs), to model and predict the complex dynamics of the hyporheic zone (HZ) driven by river stage fluctuations. The HZ is a critical transitional mixing zone between surface water and groundwater, where significant biogeochemical reactions occur. Traditional process-based reactive transport modeling methods are computationally intensive and require fine-scale parameterization. To overcome these challenges, we employ the cDC-GAN as a deep-learning-based surrogate model to predict zones of enhanced biogeochemical activity (i.e., hotspots) and reaction product concentrations in the HZ under varying bimodal sedimentary heterogeneity scenarios. The cDC-GAN model can efficiently capture nonlinear relationships between input data and output parameters without extensive parameterization, making it computationally less demanding. The model’s generative capabilities allow for the creation of new data instances, enabling the exploration of diverse scenarios and interpolation between observed data points. The model uses maps of liquid saturation and solute concentrations at different time steps to generate corresponding maps of reaction rates and reaction product concentrations. Results demonstrate the model’s qualitative and quantitative ability to capture complex relationships without relying on rigid assumptions about linearity or specific probability distribution functions. Notably, even amid variations in aquifer heterogeneity, the model consistently exhibits robust performance, validating its ability to adapt to dynamic geological settings. Our use of a simplified reaction scheme serves as a proof of concept for the cDC-GAN model’s ability to simulate solute transport in the HZ, opening avenues for future applications including more complex reaction networks within HZ system such as nutrient cycling, organic matter degradation, redox reactions, and beyond.

The Role of Risk Factors in System Performance: A Comprehensive Study with Adaptive Progressive Type-II Censoring

The quality performance of many vital systems depends on how long the units are performing; hence, research works started focusing on increasing the reliability of systems while taking into consideration that many factors may cause the failures of operating systems. In this study, the combination of a parametric generalized linear failure rate distribution model and an adaptive progressive Type-II censoring scheme for practical purposes is explored. A comprehensive investigation is performed on the risk factors that cause failure and determines which of the factors has a more harmful effect on the units. A lifetime experiment is performed under the condition of an adaptive progressive Type-II censoring scheme to obtain observations as a result of the competing factors of failures. The obtained observations are assumed to follow a three-parameter generalized linear failure rate distribution and are assumed to be competing to cause failure. Two statistical inference methods are employed for estimating this model’s parameters: the frequentist maximum likelihood method and the Bayesian approach. Our model’s validity is demonstrated through extensive simulations and real data applications in the medical and electrical engineering fields.

Effect of soil pH and mineralogy on the sorption and desorption of phosphite and phosphate in Ultisols of the Southeastern Coastal Plain

AbstractThe development of transgenic crop varieties capable of utilizing phosphite (Phi) as a phosphorus (P) source is a promising strategy to increase P use efficiency while decreasing reliance on phosphate (Pi)‐based fertilizers. However, little information is available on Phi sorption and desorption in soils. We conducted batch experiments to investigate the sorption of Phi and Pi by three Ultisols from the Coastal Plain of the southeastern United States. At the soils' acidic field pH (pH 4.7–6.2), Pi had a higher affinity than Phi for soil solids, where maximum sorbed concentrations of Pi were an average of 44% greater than those of Phi. The sorption of both P species decreased when experiments were repeated adjusting soil pH to 6.5. More Phi than Pi was recovered during desorption experiments, indicating that Phi was more reversibly sorbed and, therefore, may be more plant‐available than Pi. Multiple linear regression between calculated linear distribution coefficients (KD; 10 mg P L−1 input solutions) and soil properties suggested that amorphous Al‐ and Fe‐oxides controlled Pi sorption. Alternatively, amorphous Al‐oxides and gibbsite controlled Phi sorption. Our results show that a lower affinity of Phi than Pi in Ultisols could improve P availability for plant uptake of Phi‐based fertilizers but may increase the risk of soil P buildup over time.

Study on Calculation Method of Bending Performance of Concrete Sandwich Composite Slab.

In order to explore the flexural behavior of a concrete sandwich panel under concentrated boundary conditions, based on Kirachhoff's elastic thin plate theory in this paper, the geometric deformation, physical conditions, and equilibrium relationship of a sandwich panel are deduced by constructing the layered analysis model of the sandwich panel, the basic differential equation of the flexural deformation of the concrete sandwich thin plate is obtained, and the mathematical expression of the internal force and displacement under the boundary condition of concentrated support is given. Combined with an engineering example, the proposed calculation method is verified. The results show that, in the arrangement of reliable connectors for concrete sandwich panels, the concrete wythes bear the load while the contribution of the core layer to the bending capacity of the structure can be ignored. When subjected to a laterally distributed load, the sandwich panel mainly experiences out-of-plane bending deformation, and the bending normal stress in the concrete panel layer shows a linear non-uniform distribution along the thickness direction of the panel. The bending deformation performance and bearing efficiency of a concrete sandwich slab with the change in concentrated support position have significant effects, and the load transfer efficiency can be improved by optimizing the arrangement of supports. Except for small local areas near the supports, the bending stress distribution and deformation behavior of the concrete sandwich panel can be accurately analyzed by the calculation method established in this paper.

Spectra and equitemporal surfaces of the photosphere of the ultrarelativistic shell as applied to Gamma-ray bursts

We study the radiation of the ultrarelativistic shell in the diffusion approximation, which takes place at the initial stage of a gamma-ray burst. We get the effective temperature, instantaneous and time-integrated spectra for the parabolic distribution of the initial internal energy of the shell. Also we considered the types of the equitemporal surfaces with a different type of the movement of the shell.

High-frequency temperature-dependent vibration of nonlocal functionally graded sandwich nanoplates resting on elastic foundations

This article studies the role of temperature and nonlocality on the low- and high-frequency behaviors of functionally graded sandwich nanoplates resting on Winkler–Pasternak foundations. The small-scale effects are incorporated using nonlocal elasticity theory. The rise in temperature is characterized by the uniform, linear, and nonlinear distributions. The governing equations are solved using Navier’s solution, ensuring convergence of frequencies at any mode sequence number. A comprehensive parametric study is presented to elucidate the effects of various parameters on the low- and high-frequency behaviors of functionally graded sandwich nanoplates. The findings provide fundamental insights for the design, testing, and manufacture of nanostructures.

Equivalent Enthalpy Model and Log-Mean Enthalpy Difference Method for Heat-Mass Transfer in Cooling Towers

Abstract In industrial processes involving both heat and mass transfer, the enthalpy or total energy difference, not the temperature difference, is a more comprehensive driving-force potential for heat exchanger systems, such as a cooling tower. However, the common practice of current enthalpy methods based on Merkel integral requires numerical integration with implied linear distributions of air enthalpy and water temperature. If the cooling range is relatively small, the outcome of the integration may carry little error. But for a large cooling range and a substantially increased temperature, the error involved may be significant. Like log-mean temperature difference, a log-mean enthalpy difference method may require only the inlet and outlet conditions without prior knowledge of the enthalpy distributions of the fluids within the heat exchanger. The known Berman's enthalpy difference method requires correction factors, which was derived based on the linearization of the interfacial enthalpy and the enthalpy difference between the interfacial moist-air enthalpy and the bulk air enthalpy without underlying interpretation to demonstrate that the method could be broadly used. In this paper, an equivalent enthalpy model is proposed, and the log-mean enthalpy difference is derived without any constraints for broad uses. The derived method is compared with the results of Merkel's method from literature with excellent agreement. Thus, the work in this paper would open the possibility for broad uses of the log-mean enthalpy difference method for many industrial processes involving mass transfer.

Testing Bell–CHSH inequalities using topological Aharonov–Casher and He–McKellar–Wilkens phases

The effects of Aharonov–Casher (AC) and He–McKellar–Wilkens (HMW) phases on entangled spin-1/2 quantum systems are investigated. We use linear charge distributions positioned at the center of resulting closed orbits, capitalizing on Mach Zender-type interferometers modified with phase retarders to unveil the topological effects. We analyze how AC-HMW phases influence the Bell angles and maximal violation of Bell–CHSH inequalities (BI) without any classical interaction. We incorporate the spin and path of particles in the interferometers as observables to test noncontextual hidden variable theories against quantum mechanics, leveraging the non-local features of AC-HMW effects. Furthermore, we discuss potential implementations of our scheme in physical systems.