Energy Characteristics Research Articles

EEG-Based Early Detection of Autism Using Convolutional Neural Networks

This Timely intervention and improved management of autism spectrum disorder (ASD) are contingent upon early detection. In this paper a novel method for early autism identification using EEG signals and convolutional neural networks (CNNs) is proposed. Preprocessing, wavelet transform, Discrete Cosine Transform (DCT) , energy and entropy function feature extraction, and CNN classifier classification are some of the phases in the suggested approach. EEG signals are first pre-processed to get rid of artifacts and noise. Then, to extract pertinent characteristics from the EEG signals, wavelet transform and DCT are used. For feature extraction, energy and entropy calculations are used to identify unique patterns suggestive of ASD. After then, a CNN classifier receives these features and divides them into two categories: Autism identified or normal identified. The accuracy, specificity, sensitivity, and precision of the suggested approach are among the performance measures that are used to assess its effectiveness. With an accuracy of 92.34%, specificity of 92.95%, sensitivity of 92.65%, and precision of 92.65%, the experimental findings show encouraging performance. When compared to current systems, the suggested approach performs significantly better, outperforming the 91.78% accuracy of the current system.

Exploring the impact of end-capped benzothiazine-based acceptors to lead the photovoltaic properties of solar cells: A DFT/TD-DFT approach

To improve the solar cells performance, usually end-capped acceptors are used in designing of new molecules. Therefore, in this study, the side-chain and end-capped moieties were modified in reference compound (BTZR) and proposed new compounds (BTZD1-BTZD6) to augment their photovoltaic and optoelectronic properties. The density functional method was employed at the M06/6-311G(d,p) level to optimize and interpret their frontier molecular orbitals (FMOs), density of states (DOS), transition density matrix (TDM), exciton binding energy (Eb), light absorption and open circuit voltage (Voc) characteristics. Their global reactivity parameters (GRPs) were calculated via the HOMO-LUMO energy band gap. Further, it was observed that all the investigated compounds showed lower band gaps (2.975–3.160 eV) and bathochromic shifts in the visible region (482.501–504.223 nm). Various plots such as the DOS, TDM and hole-electron further confirmed the efficiency of designed chromophores. Additionally, an interface of model donor–acceptor was constructed by considering the donor polymer (PBDB-T) and designed NFAs. Significant results were obtained for Voc (1.538–1.772 V). Among the selected candidates, BTZD3 and BTZD5 were obtained as high-performance non-fullerene acceptors (NFAs). They exhibited least band gaps (2.988 and 2.975 eV) and highest λmax (504.223 and 498.606, respectively). These compounds also demonstrated the least exciton binding energy values as 0.529 and 0.488 eV, respectively. Besides this, comparative study with the standard hole transport material (HTM) spiro-OMeTAD showed a reasonable agreement, suggesting that the entitled compounds could serve as effective HTMs. Overall, the findings suggested the crucial role of end-capped modification in elevating the charge mobility and photovoltaic characteristics of BTZD1-BTZD6. This study provides a valuable insight in the development of good photovoltaic materials.

The effect of several factors on energy characteristicsand burning of pyrotechnic compositions based on silic and trilead tetraoxide in some pyrotechnic devices

Pyrotechnic ignition is one of the important parts of the delay timing devices found in fuses and rockets to provide operational reliability according to technical requirements. In this study, the burning rate and some energy characteristics of the pyrotechnic ignition were described. The research results showed that pyrotechnic compositions containing 85.0% Pb3O4, 15.0% Si, and 1.0% NC (over 100%) had a high and stable burning rate (109.0 mm/s) and good ignition ability.

Energy-saving mechanism and dynamic characteristics of blade angle adjustment in low head pumping system

To investigate the energy-saving mechanisms and dynamic characteristics of blade angle adjustment, this study proposes a novel research method via simulations, prototype and model testing. For stable conditions, the internal field, the external and energy characteristics of the pumping system with different blade angle are examined. The dynamic characteristics of the pumping system and the blade force characteristics during the adjustment process are also studied. The research results show that, under a certain net head, an appropriate impeller blade angle improves the flow state in the pump and conduits, decreasing the entropy production and providing suitable inlet circulation to reduce the hydraulic loss of outlet conduit, thereby improving the pumping system efficiency by 5–10 percentage points. During the adjustment process, there is an approximate 20-s delay in dynamic characteristics. Additionally, with the increase of the blade angle, the hydraulic torques for blade axis and pump shaft increase, thus increasing the blade adjustment force and shaft power. The adjusting force is found to be underestimated in the adjustment processes of decreasing the blade angle. Achievements of this paper contribute to high efficiency of pumping system and high reliability of blade adjustment devices and pump units.

High dynamic range land wavefield reconstruction from randomized acquisition

Compressive sensing (CS) is an alternative to regular Shannon sampling that captures similar information from reduced measurements. It relies on randomized sampling patterns and a sparse data representation to reconstruct the regularly sampled object. CS is an important ingredient in affordable seismic acquisition, which can lead to improvements in the near-surface mapping and noise suppression for land data. However, the near surface traps most of the source-generated energy, resulting in data that are rich in high-wavenumber content and have amplitudes spanning several orders of magnitude. When dealing with such high dynamic range nonstationary data, the Fourier domain is not optimal for providing a sparse representation — a necessary condition for successful application of CS. In contrast, a discrete complex wavelet transform can localize high-energy features, has good directional selectivity, and is near-shift invariant. Combined, these properties allow complex wavelets to represent detail-rich wavefields in a compact form. To leverage these features and achieve good CS reconstructions, we develop a scale- and orientation-dependent iterative soft thresholding (IST) scheme for reconstructing high dynamic range wavefields. Our approach requires little parameterization, is easy to implement, and is robust to reconstructed wavefield sampling grid and dynamic range. We test IST on different wavefields with randomly missing traces and compare the data reconstructions with the spectral projected gradient solver and projection onto convex sets. We quantify the reconstructions by a direct comparison of Fourier coefficients between fully sampled and reconstructed wavefields. Taking log10 of Fourier coefficients prior to computing the quality metric deemphasizes the importance of magnitude match while highlighting Fourier coefficient support accuracy, which usually translates into good structural fidelity of reconstructed data. We find that IST performs consistently among all examples, yielding good phase match while performing gentle denoising.

Two-Stage Optimization Scheduling of Integrated Energy Systems Considering Demand Side Response

This study proposes a two-level optimization scheduling method for multi-region integrated energy systems (IESs) that considers dynamic time intervals within the day, addressing the diverse energy characteristics of electricity, heat, and cooling. The day-ahead scheduling aims to minimize daily operating costs by optimally regulating controllable elements. For intra-day scheduling, a predictive control-based dynamic rolling optimization model is utilized, with the upper-level model handling slower thermal energy fluctuations and the lower-level model managing faster electrical energy fluctuations. Building on the day-ahead plan, different time intervals are used for fast and slow layers. The slow layer establishes a decision index for command cycle intervals, dynamically adjusting based on ultra-short-term forecasts and incremental balance corrections. Case studies demonstrate that this method effectively leverages energy network characteristics, optimizes scheduling intervals, reduces adjustment costs, and enhances system performance, achieving coordinated operation of the IES network and multi-energy equipment.

Experimental study of a turnstile aperiodic HF-band antenna with a terminal load in the form of a near ground four-arm spiral antenna

It is known that the energy characteristics of four-arm spiral near ground antennas with internal power supply (at the geometric center) vary significantly depending on the order of excitation of their inputs. When excitation of the arms of such antennas in the cross-polarization mode, their efficiency of radiating electromagnetic waves decreases by an order of magnitude or more; the article proposes an excitation method that is free of this drawback. The aim of the article is an experimental study of the comparative effectiveness of a near ground four-arm spiral antenna of the HF-band and the antenna system it is part of, when changing its excitation type (from internal to external) and mode (main and cross-polarization). A detailed description of the design of the antenna system and the method of implementing the excitation of its emitters are proposed. The proposed design of a phase-shifting device based on a Butler matrix can be used for effective electromagnetic waves radiation or reception by an antenna system of both right and left circular polarization. The results of the analysis of methods for excitation of a near ground four-arm spiral antenna presented in the article can be used in the design or modernization of antenna systems of ionosondes or radio centers with increasing their efficiency.

THERMAL TREATMENT OF AGRICULTURAL WASTE AS AN ALTERNATIVE FOR PRODUCING SOLID BIOFUELS

Brazil stands out in terms of the composition of its energy matrix, with biofuels playing an important role, with many different raw materials requiring study. This article seeks to evaluate thermal treatment's effect on different biomass species to improve their energy characteristics, through an analysis of immediate chemical composition (as standardized by the American Society for Testing and Materials), spectroscopy in the infrared region, and thermogravimetry. This paper details the energy potential for each biomass, establishing the torrefaction processes with the best yield from agricultural residue of peanuts (Arachis hypogaea L.), cacao (Theobroma cacao L.), sugarcane (Saccharum spp.), coconut (Cocos nucifera L.), palm oil (Elaeis guineensis Jacq.), and papaya (Carica papaya L.). The thermal treatment of biomass proved effective in obtaining a solid biofuel with a higher heating value, as diagnosed through immediate chemical analyses.

Study on the Deformation and Energy Evolution of Skarn With Marble Band of Different Orientations Under Cyclic Loading: A Lab‐Scale Study

ABSTRACTThe aim of this work is to investigate the deformation and energy characteristics of skarn with different interlayer inclination angles under cyclic loading. The skarn samples with marble bands of various orientations (i.e., 30°, 45°, 60°, and 75°) were chosen as the test material. It is revealed from the testing results that the presence of interlayers changes the geomechanical properties of the rock, rock peak strength, and elastic modulus increases with increasing the interlayer inclination angle. Additionally, the growth rate of input energy exhibits an inverted “V” pattern with respect to the interlayer inclination angle. In terms of damage modes, intact marble and skarn predominantly exhibit tensile damage, whereas interlayered rocks exhibit a combination of tensile and shear failure pattern. Finally, a damage evolution model defined by axial strain is proposed and expressed to fit the experimental data. The results in this work would provide a crucial theoretical basis for the safety assessment of underground engineering constructions.

Fog Harvesting Via Multistage Edge‐Effect Condensation

AbstractThe escalating global population and rapid industrialization have precipitated a severe freshwater scarcity crisis. To address this challenge, innovative strategies are essential to exploit unconventional water sources such as atmospheric vapor. This study proposes a novel approach integrating 3D printing technology with surface chemistry principles for atmospheric fog harvesting. The approach entails leveraging 3D printing technology, chosen for its cost‐effectiveness, unparalleled design flexibility to design intricate geometries, and time efficiency to fabricate cylindrical millimeter‐scale size vertical pillars. Harnessing the intricate interplay of surface phenomena, condensation preferentially occurs on the pillar tops due to surface phenomena. The pillars are imbued with nonadecane, a hydrocarbon renowned for its low surface energy characteristics ensures the uninterrupted progression of water droplet formation, coalescence, and seamless transportation, unveiling a symphony of molecular interactions at the microscale. The design demonstrates promising results, yielding an impressive yield of ≈3.956 g of water per hour from 1 cm2 area. Geometric discontinuities associated with parahydrophobic pillars amplify water harvesting via an edge effect. This study represents a significant step toward a more sustainable and technologically advanced solution for the global water crisis.

Development of an extracorporeal pump for ECMO systems

Objective: today, extracorporeal membrane oxygenation (ECMO) systems remain the main type of short-term circulatory support in various clinical situations. One of the main elements of this system is a blood pump. The objective of this study is to develop the first domestic centrifugal pump for use in ECMO systems.Materials and methods. Based on a systematic literature review, the main medical and technical requirements for an extracorporeal centrifugal pump were formulated. To create 3D mathematical models of the outer casing of the pump and all its internal components, calculations were performed in CAD software package SolidWorks (SolidWorks Corp., USA). Hydrodynamic test benches were designed and developed to evaluate the performance of the centrifugal pump mockup. The pump was studied to obtain its head-capacity curve (HCC) and hemolytic characteristics.Results. 3D modeling of geometrical parameters of the pump flow impeller was performed. Fluid flow was assessed in the rotor rotation range at speeds from 3000 to 7000 rpm. Hydrodynamic bench tests were performed under conditions simulating the resistance of the oxygenator and connecting cannulas. The HCC was obtained based on the given medical and technical requirements for the operating flow range from 1 to 5 l/min at pressure dropsof 200 to 400 mm Hg.Conclusion. Based on results from the 3D modeling and bench experiments, a model of extracorporeal centrifugal pump was obtained, which showed its efficiency during the first trials. Further experimental studies will be conducted to obtain the energy and biological characteristics of the developed device.

DEVELOPMENT OF THE THEORY OF GAS FUEL COMBUSTION TAKING INTO ACCOUNT MODERN KINETIC MECHANISMS OF COMBUSTION

An actuality of modernizing advancement the modern adopted combustion theory is due to a significant change in the composition of fuels at the market of developed countries by rejection of basic mineral (organic) fuels (fossil fuels), which have been used in the world for 250 years. The transformation of traditional fuels’ orientation towards an application of carbon-free fuels, primarily to hydrogen and its mixtures with natural gas. Each way of mentioned activity is connected with to ensure an environmental decarbonisation. Criteria for evaluating the CO2 emissions by fuels’ choice and selection have been proposed while numerical calculations of the specific CO2 content in the combustion products of the hydrocarbon-hydrogen mixture jʹ and j have been evaluated. It is possible to reduce these values when adding the shared H2 in the fuels (m3 CO2/ MJ; kg CO2/ MJ). Considering the combustion process in combustion systems (combustion chambers, boilers, furnaces) at constant pressure (p =const, dp =0 — isobaric process), the enthalpy of the reactants’ flow of the mixture (total (chemical) enthalpy I) can serve as a measure of the specific energy of the reacting mixture. An approach is proposed, according to which the main equations of heat and mass transfer in the torch (premixed flame) are composed basing upon the principle of conservation the total (chemical) enthalpy representing energy as basic function. The basic approach to the development of a modern combustion theory is focused on the concept of T. von Karman, according to which the combustion process is considered as “aerothermochemistry”, i.e. the description of physical and chemical processes is based on the combination of heat and mass transfer equations with chemical kinetics’ equations. At the current period, the problem of chemical kinetics (burning process) is considered through the combustion mechanisms of basic fuels, which consist of a large number of equations for molecules and particles involved in process at various stages of the combustion — from the preheating of the reaction mixture and through the stage of ignition (or self-ignition) — to the final temperature of flue gases. The laminar combustion velocity SL is a determinative characteristic of the combustible properties of gas fuels and, accordingly, of the safety restrictions by the fuel choice. Quantitative values of SL for the separate basic fuels, including the hydrogen, both the organic (fossil fuels) and alternative ones could be differed by an order of magnitude and more. The problem of estimable forecasting the SL value provides an option of the composition of the fuel-oxidant mixture in the industry, power and municipal energetics. The SL value’s prediction makes an especially important action at the current stage of modelling completion with an account of the global warming and by preventing an excess of CO2 emissions, including involvement of hydrogen-containing gases by substitution the carbon-friendly fuels, firstly the fossil fuels. The contemporary theory of combustion has been developed by extensive use the adequate kinetic mechanism GRI-Mech 3.0, the universality of which has been confirmed by our calculations of SL values for a wide range of the gas fuels — from methane CH4 to hydrogen H2 and their mixtures. An advanced modern theory of combustion using the adequate and approved GRI-Mech 3.0 combustion kinetic mechanism has been developed. The universality of this mechanism is confirmed by our calculations of SL values for a wide range of gaseous fuels — from methane CH4 to hydrogen H2 and their mixtures (mixed gases MG). For further analysis and development, the model of combustion in the reacting flow by Y.B. Zeldovich and D.A. Frank-Kamenetsky was used, considering the transfer processes of total enthalpy I as the energy characteristic of the combustible mixture. The kinetic component (on the example of natural gas) is taken into account using the combustion mechanism for GRI-Mech 3.0. The latter summarizes the combustion process of through 325 constituent reactions for 53 components. The adequacy of the combustion model proposed in the paper is confirmed by numerical examples of the coincidence of numerical SL values: ours — calculated; literary — experimental. The validity of experimental values of SL is provided by the use of different methods of measuring the SL. Calculations of the specific total enthalpy I of the reacting mixture along the length x º l (thickness of the front for a homogeneous flame in a one-dimensional formulation) have been performed as a result of researches confirmed the initial position: I(x) = const with deviations for CH4 +7 % / –2 %; for H2 +9,2 % / –2,8 % in relation to the heat of combustion. Bibl. 52, Fig. 9, Tab. 3.

Experimental study on physico-mechanical responses and energy characteristics of granite under high temperature and hydro-mechanical coupling

Thermal and hydro-mechanical coupling effects on granite's physico-mechanical responses and energy characteristics can influence its carrying capacity, hydraulic and heat transfer performance. The evolution of these properties is crucial for geothermal reservoir stability assessment and the optimization of deep geothermal energy development techniques. Hence, a variety of physical tests and rock mechanics experiments were conducted. Key findings include: (1) As temperature rises, granite undergoes thermal expansion and structural integrity degradation. The peak strength σp, elastic modulus E, total energy density U, and elastic energy density Ue initially rise at 25 °C–150 °C and subsequently decrease above 150 °C, while the proportion of dissipated energy ηd is opposite. Granite also initially experiences hardening, then turns to brittle-ductile transition. (2) The crystallinities of quartz, albite, and orthoclase demonstrate substantial deterioration beyond 450 °C. (3) 150 °C and 450 °C are regarded as the temperature thresholds for mechanical properties. (4) As confining pressure rises, granite experiences hardening, with σp, E, U, and Ue increasing, and ηd decreasing. (5) Pore water pressure increases ηd and decreases σp, E, U, and Ue, and its effect on the mechanical responses is pronounced when it reaches 80 % of confining pressure or exceeds 450 °C.

Co-effects of parallel flaws and interface characteristics on the fracture behavior of rock-concrete composite specimens

The fracture behaviour of rock-concrete composite (RCC) containing interfaces and flaws is important for assessing the stability and safety of concrete systems constructed on rock foundations. Uniaxial compression experiments were performed on RCC specimens, and acoustic emission (AE) and digital image correlation (DIC) techniques were adopted to capture the characteristics of AE and crack extension process. The impacts of interface dip angle, concrete strength, and flaw geometry on the coalescence behavior of RCC specimens were analyzed. The findings indicate that four kinds of crack coalescence patterns were recognized: indirect coalescence, left-tip and right-tip cracks connected, coalescence of same-side tip cracks, and no connection. The peak strength displays a reducing trend with increasing the interface dip angle, while the peak strength presents an increasing trend with increasing concrete strength. The overlapping parallel distribution of composite specimens presents a higher peak strength. The crack coalescence mode of overlapping parallel distribution changes from the coalescence of same-side tip cracks to the no-connection mode when interface dip angle is larger. It is worth noting that cracks tend to appear first in the concrete when the strength is relatively low. The AE counts tended to increase as the interface dip angle increased, with the earliest rise in AE counts in the left-stepping distribution and longer duration in the overlapping parallel distribution. Additionally, the energy characteristics of composite specimens correlate closely with the interface dip angle and flaw geometry.

Investigation of Some Oat (Avena sativa L.) Genotypes in Terms of Grain Yield and Quality

This research was conducted to compare different agronomic characteristics of some oat (Avena sativa L.) genotypes. The research was carried out in the trial fields of Trakya Agricultural Research Institute, located in Edirne, in 2018-2020. In the experiment, 15 oat genotypes along with 5 standard varieties namely; Kırklar, Kahraman, Küçükyayla, Yeniçeri and Sebat were used. The research plan was designed according to the Randomized Complete Block Design using three replications. In the study, thousand grain weight (TGW), hectolitre weight (HW), relative feed value (RFV), metabolic energy (ME), crude fibre (CF), crude ash (CA) and dry matter digestibility (DMD) characteristics were examined. As a result of this study, all the characteristic values of oat showed significant differences in terms of years except for; DMD. Additionally, all the examined traits showed significant differences in terms of genotypes. The average mean values of TGW, HW, RFV, ME, CF, CA and DMD of examined genotypes showed variation between 24.1-43.2 g, 50.1-62.6 kg/hl, 205.0-328.3, 2.56-2.76 Mcal/kg, 7.88-13.82%, 4.35-5.83% and 73.1-78.3%, respectively. Generally, genotypes 3 and 5 took the first place in terms of grain yield, whereas the genotypes 3, 4, 6, 10 and 11 in terms of grain nutritional values. Consequently, it is concluded that the genotypes 3, 4, 6, 10 and 11 have higher values in terms of the examined traits as compared to the rest genotypes. So, these genotypes would be more suitable for oat cultivation under similar ecological conditions with the expectation of satisfactory economic benefits.

Transient voltage stability assessment and margin calculation based on disturbance signal energy feature learning

With the increasing variation of the network topology and the high complexity of the processing measurement data, the transient voltage stability assessment of the new power system is facing significant challenges in low accuracy and high time costs. To address the shortcomings of the existing method and apply it to online assessment, this paper proposes an assessment method based on feature learning for disturbance signal energy (DSE) from bus voltages. Firstly, the relationship between DSE and system transient voltage stability is established, and the calculation of DSE from bus voltage time series is detailed. Subsequently, a transient voltage stability assessment method based on the ID3 Decision Tree algorithm and DSE is proposed. Finally, by employing the Support Vector Machine (SVM) to construct the optimal boundary in the feature space formed by the key buses, the transient voltage stability margin (TVSM) for specific scenarios is proposed. Simulation results on the IEEE 39-bus system demonstrate that the proposed method can rapidly and accurately assess the transient voltage stability of the system and calculate the stability margin, providing intuitive and interpretable results with high engineering application value.

Generated power forecast of dye-sensitized solar plant with deep neural network

ABSTRACT The enormous amount of solar power and its state-of-the-art capturing technology that produces electricity, increases the grid interconnection rate of photovoltaic (PV) plants. Prior knowledge of the aperiodic characteristics of solar energy received by the Earth’s surface is essential for PV plants to ensure reliable operation and stable, secure grid connections. Power generation under diffused sunlight by PV plants with the most widely used first-generation solar cells has significant limitations. A dye-sensitized solar plant (DSSP), utilizes dye-sensitized solar cell (DSSC) technology, remains active in low light conditions. Though the activeness enables such plants to generate electricity throughout the year while receiving diffuse sunlight, unlike conventional solar technologies the plants have a requirement of knowledge of future power generation. This could be the first paper to report on the generated power forecast for such plants. The study has utilized a machine learning approach with a proposed DSSP model for the forecast. Spyder, an open-source integrated development environment, is the test workbench for the experimentation. The results show the robustness and reliability of the method, regardless of the weather conditions in the test area. The DSSP, along with the prediction model, will moderately overcome the shortcomings of power generation under diffuse daylight with intermittent solar radiation and grid connections.

Statistics of unidirectional wave groups with and without freak waves observed in the Norwegian Sea

The statistical properties of observed wave groups are essential for designing marine structures. However, the characteristics of group energy, length, and profiles remain unclear. This paper analyzes more than 1 million measured ocean unidirectional wave groups in deep water of the Norwegian Sea during a decade. By classifying wave groups into ordinary and extreme categories based on the presence of a freak wave, it is found that both the distributions of the non-dimensional group energy and group duration follow the Generalized extreme value functions. Moreover, the statistics of wave groups are significantly influenced by the spectral width, with wave steepness having negligible effects. The ratio of the average group duration between extreme and ordinary categories varies slightly from 1.4 to 1.8, although the energy of extreme wave groups can reach 3.0–4.5 times than that of ordinary wave groups. Furthermore, unlike the typical shape of a freak wave with a high wave crest or deep wave trough significantly larger than the surrounding waves, consecutive large waves resembling the “three sisters” are quite common in this location. However, NewWave theory generally underestimates the wave amplitudes surrounding a freak wave, leading to the predicted energy of the most likely extreme wave groups being only about 50–80% of the measured values. Finally, a new modified model is proposed to predict the average shapes of extreme wave groups. After testing numerous wave cases, the model accurately captures the mean morphology of extreme wave groups in the Norwegian Sea.

Numerical model for the solidification of a chondrule melt

In this study, we propose a novel numerical method to simulate the growth dynamics of an olivine single crystal within an isolated, multicomponent silicate droplet. We aimed to theoretically replicate the solidification textures observed in chondrules. The method leverages the phase-field model, a well-established framework for simulating alloy solidification. This approach enables the calculation of the solidification process within the ternary MgO–FeO–SiO2 system. Furthermore, the model incorporates the anisotropic characteristics of interface free energy and growth kinetics inherent to the crystal structure. Here we investigated an anisotropy model capable of reproducing the experimentally observed dependence of the growth patterns of the olivine single crystal on the degree of supercooling under the constraints of two-dimensional modeling. By independently adjusting the degree of anisotropies of interface free energy and growth kinetics, we successfully achieved the qualitative replication of diverse olivine crystal morphologies, ranging from polyhedral shapes at low supercooling to elongated, needle-like structures at high supercooling. This computationally driven method offers a unique and groundbreaking approach for theoretically reproducing the solidification textures of chondrules.

Study on cavitation characteristics of a waterjet pump under off-design conditions

Abstract Water jet pump is widely used in power field, and ordinary axial impeller is the key component of energy conversion. Because of the existence of tip clearance, the tip leakage flow through the clearance is inevitably accompanied by energy loss. Taking the axial-flow water jet pump as the research object, the condition is that the pump runs under the condition of deviating from the design condition. Considering the influence of vortex and cavitation, the improved numerical model is used to simulate the internal flow field. SST-CC turbulence model considering rotation correction and modified Zwart cavitation model based on vortex identification correction are selected. The cavitation performance and Vortex characteristics under off-design conditions are analyzed. The results show that flow loss is mainly reflected in turbulence dissipation and wall dissipation, which the turbulence dissipation and wall dissipation of impeller section account for the largest proportion. Because the cavitation area of water jet pump is mainly concentrated in the impeller, the turbulent dissipation is mainly related to the characteristics of turbulence kinetic energy and turbulent vortex. The research results can provide an effective basis for the analysis and design of axial-flow water jet pump.