Search Results (14,860)

The depletion of global reserves of high-quality sulfide nickel deposits, coupled with the steady growth of nickel demand, has led to increased interest in the processing of oxidized (lateritic) nickel ores, including deposits with significant resource potential in the Republic of Kazakhstan. This paper provides an overview of global nickel ore reserves and their distribution, as well as the major nickel deposits in Kazakhstan, which are primarily located in the Aktobe, East Kazakhstan, Kostanay, and Pavlodar regions. Pyrometallurgical processing routes for lateritic nickel ores are also considered. Conventional production technologies, including the Rotary Kiln–Electric Furnace (RKEF), Krupp–Renn process, blast furnace smelting, Vaniukov process, and ISASMELT process, are reviewed, and their process flow diagrams are presented. These methods typically process lateritic nickel ores containing more than 1.2% Ni, whereas Kazakhstan ores are characterized by lower nickel grades, generally in the range of 0.75–1.1%. The advantages and limitations of conventional processing routes are analyzed, and the factors limiting the effective beneficiation of lateritic nickel ores using traditional methods are identified. The present study substantiates the feasibility of producing nickel-containing alloys from lateritic nickel ores using a metallothermic reduction approach. This method is based on the reduction of nickel and iron oxides using metallic reductants, which enables more selective extraction of target components and the formation of alloys with controlled composition. Metallothermic reduction is of particular interest for the processing of low-grade lateritic ores, as it allows the production of nickel-containing alloys without prior beneficiation, at lower energy consumption, and with reduced sensitivity to variations in the chemical and mineralogical composition of the raw materials. Therefore, this approach is considered a promising direction for the processing of lateritic nickel ores in Kazakhstan. Full article

The treatment of spent drilling fluids generated during the drilling of technological wells for uranium production represents an important engineering and environmental challenge associated with high energy consumption, significant waste generation, and the need for rational water use under arid regional conditions. Conventional phase separation methods based on gravitational settling and chemical–mechanical treatment are characterized by limited process controllability, long processing times, and increased consumption of reagents and energy. This study proposes an energy-efficient and reliable hydrodynamic technology for the treatment of spent drilling fluids based on the formation of controlled turbulent structures without the use of mechanical drives. The research object comprised spent drilling fluids (SDFs) generated during the drilling of technological wells for uranium production in the southern regions of the Republic of Kazakhstan and the Kyzylorda region. Experimental investigations were carried out using a laboratory–pilot hydrodynamic disperser with variations in velocity gradient, treatment time, flocculant dosage, and suspension flow rate. A mathematical model linking hydrodynamic process parameters with phase separation kinetics and energy characteristics was developed. Model calibration by weighted nonlinear least squares yielded a stable parameter set with 95% confidence intervals, and model validation demonstrated good agreement between calculated and experimental data (MAPE 8.4%; maximum relative error 11.8%). It was established that the use of a hydrodynamic disperser provides separation efficiency of up to 90–95% under optimal operating conditions while reducing specific energy consumption and maintaining stable repeated-cycle performance within the investigated operating window. Experimental results confirm that implementation of the hydrodynamic technology enables a reduction in sludge volume by 40–60%, recovery of up to 60–80% of process water, and a significant decrease in waste requiring transportation and disposal. The obtained results demonstrate the high environmental and resource-saving efficiency of the proposed technology and its suitability for scaling and industrial implementation at facilities drilling technological wells for uranium production. The developed hydrodynamic approach can be considered an effective engineering platform for creating energy-efficient and sustainable systems for drilling fluid treatment in regions with limited water resources and remote industrial infrastructure. Full article

The distribution of gas–water two-phase flow in near-horizontal wells is influenced by factors such as wellbore inclination and phase flow rates. To explore these effects, a laboratory loop simulating downhole conditions was used to conduct experiments under varying inclinations and flow parameters. Flow patterns were classified based on visual observations and existing theory, and scatter plots were used to analyze flow regime boundaries. Three classification models were developed and compared. The proposed PNN–XGBoost framework integrates explicit second-order feature crossing with XGBoost-based importance selection prior to probabilistic neural network classification. Among the evaluated models, the PNN–XGBoost approach achieved the highest predictive performance. The model was further validated using 3D wellbore holdup imaging, confirming its robustness in flow pattern identification and its applicability to practical well logging interpretation. Full article

Shared autonomous vehicle (SAV) services are gaining attention as an innovative urban transportation paradigm due to their potential to lower travel costs and improve operational efficiency. Unlike manually operated vehicles, SAVs exhibit unique behavioral dynamics, including safe passenger pick-up and drop-off processes, as well as strategic repositioning and autonomous parking to anticipate future travel demands. Consequently, effective and dynamic route planning is paramount to optimizing SAV safety and operational efficiency. This study proposes a novel traffic information, termed Autonomous Driving Stress (ADS), designed to enhance the safety and efficiency of SAV route planning by quantitatively capturing the level of driving challenge encountered during autonomous operation. To predict ADS, a machine learning framework was developed, utilizing microscopic traffic simulation data that incorporates a comprehensive set of 22 input features describing SAV driving behavior, roadway characteristics, and prevailing traffic conditions. Among five machine learning algorithms evaluated, Random Forest exhibited superior predictive performance, achieving an accuracy of 80.9%. The proposed framework enables real-time ADS level prediction by continuously integrating streaming traffic data into the trained model. The dissemination of this real-time ADS information to SAVs supports proactive, informed, and dynamic route planning decisions, thereby enhancing operational safety, traffic flow, and the sustainability of SAV operations within urban mobility systems. Full article

Insulin acts in the brain to promote satiety. Aging individuals may have brain insulin resistance and altered appetite perceptions. However, it is unclear if exercise impacts cerebral reward centers and appetite perception in middle-aged to older individuals. Purpose: To assess whether a single exercise bout alters cerebral blood flow (CBF) in reward centers in relation to appetite perceptions. Methods: Fifteen sedentary adults (12F; ~56 ± 2y; ~31 ± 1 kg/m²) completed a control and acute exercise condition (70% maximal oxygen consumption) in a randomized, counterbalanced order in the evening. Following an overnight fast, CBF in the accumbens, thalamus, and amygdala (pCASL MRI) was evaluated before and after intranasal insulin spray (INI, 40 IU) administration. Plasma glucose and insulin as well as an appetite visual analog scale (VAS) were assessed at fasting, 30, and 90 min post-INI, as well as at 30 min intervals of a 120 min 75 g oral glucose tolerance test (OGTT). Total area under the curve (tAUC) was calculated. Results: Exercise tended to lower blood glucose (p = 0.072) and plasma insulin (p = 0.007) tAUC, compared with rest. Exercise also raised right thalamus (p = 0.029) and left amygdala CBF (p = 0.023). The rise in fasting CBF in these regions, and the accumbens, correlated with reduced insulin tAUC (r = −0.55 to −0.73, p < 0.050). Although there was no difference in hunger, satisfaction, fullness, or prospective food consumption after exercise, changes in INI-stimulated thalamus CBF related to fullness tAUC after exercise (r = −0.57, p = 0.044). Conclusions: A single exercise bout might increase fasting CBF in some brain regions associated with appetite perception through a potential insulin-related mechanism. Full article

We develop a local, patchwise geometric framework that embeds a broad class of potential Hamiltonian dynamical systems into a family of Riemannian Hamilton patches built over an underlying Gutzwiller manifold. We adopt a conformal (Jacobi) ansatz and a frame-adapted reconstruction procedure, through which we construct, on each patch, a pulled-back metric, along with a reduced (truncated) connection (not a metric-compatible connection) and a corresponding dynamical curvature tensor governing geodesic deviation in the Hamilton coordinates. Then, using the Poisson–Hodge reconstruction, we reconstruct coordinate potentials, enforcing harmonic obstructions, and along with exactness and Jacobian nondegeneracy conditions, we obtain explicit elliptic bounds that control the connection and curvature residuals. On the basis of this construction, we formalize the notion of a Hamilton manifold such that reparametrized geodesics approximate Newton trajectories with controlled acceleration and tolerances. As a generalized structural framework, to promote the local Jacobi reconstructions to a coherent dynamical evolution and provide a dynamical closure, we introduce a patchwise hyperbolic geometric flow for the pullback metric coupled to a kinetic (Vlasov) closure that controls reconstruction and curvature residuals. Under natural regularity, ellipticity, and overlap-tolerance assumptions, together with precise estimates that control the reconstruction and curvature errors, we establish short-time well-posedness of the coupled Vlasov–hyperbolic geometric flow that defines the patchwise Hamilton manifold. Motivated by this construction of the Hamilton manifold with atlas-dependent time, we propose convergence and stability conjectures for dissipative and conservative (non-dissipative) hyperbolic geometric flows. On a single patch, these conjectures characterize local orbital stability (in the sense of coercivity modulo symmetry) and identify local linear instability when unstable linear modes are present. On a finite atlas (the Hamilton manifold with atlas-dependent time), we state conjectures under which local stability propagates to global stability, provided that overlap residuals remain uniformly sufficiently small. The framework identifies the geometric origin of local instability diagnostics used in Hamiltonian mechanics and outlines a practical strategy for verifying stability or instability, numerically or analytically, on finite coverings of configuration space (the Hamilton manifold). Full article

Background/Objectives: Peak cough flow (PCF) is an objective measure of cough effectiveness after stroke, but biomarkers reflecting physiological vulnerability related to reduced PCF are not well established. We investigated whether bone turnover markers (BTMs)—C-terminal telopeptide of type I collagen (CTX) and procollagen type 1 N-terminal propeptide (P1NP)—were associated with PCF in subacute ischemic stroke. Methods: In this retrospective study, 112 patients admitted within 21 days of stroke onset had fasting morning CTX and P1NP measured by electrochemiluminescence immunoassay, and PCF measured within 72 h of admission. Associations were assessed using Spearman correlation and multivariable linear regression with BTMs standardized (per 1 standard deviation increase), adjusting for age, sex, body mass index, onset-to-admission days, National Institutes of Health Stroke Scale score, Korean version of the Modified Barthel Index, estimated glomerular filtration rate, smoking status, and brainstem lesion. Results: CTX showed an inverse correlation with PCF (rho = −0.469; p < 0.001) and remained independently associated with lower PCF after multivariable adjustment (β = −42.32 L/min; 95% confidence interval, −56.12 to −28.52; p < 0.001), whereas P1NP showed weaker associations. In secondary outcome analyses, higher CTX was associated with low PCF (PCF < 160 L/min), aspiration pneumonia, and longer length of stay. Conclusions: Higher CTX levels were independently associated with lower peak cough flow and selected respiratory-related outcomes in this retrospective cohort. These findings are hypothesis-generating, do not imply prognostic validation, and warrant confirmation in prospective multicenter studies assessing incremental predictive value. Full article

The aim of this research was to calculate hemodynamics of intracaranial aneurysms using computational fluid dynamics. The hemodynamics research of intracranial aneurysms used patient-specific blood pressure data and anonymised DICOM images, from which aneurysm geometries were extracted. The following boundary conditions were established. At the inlet, a pulsatile velocity profile was enforced, and a pressure waveform was assigned at the outlet. Numerical simulations were performed to examine key hemodynamic parameters linked to aneurysm rupture, including wall shear stress, time-averaged wall shear stress, oscillatory shear index, and relative residence time, as well as flow distributions. On the basis of these hemodynamic indicators, the risk of rupture was connected with a geometric property of the aneurysm, the aspect ratio. The hemodynamics parameters obtained ranges with the results of other scientific studies. Finally, it was concluded that combining clinical data, aneurysm geometry, and hemodynamic characteristics can provide clinicians with valuable additional information to use in selection of the appropriate treatment strategy for intracranial aneurysms. Full article

A high-speed magnetic pump rated at 7800 r/min was studied. A numerical model was established, and a hydraulic, vibration, and noise testing system was set up to conduct flow simulations, noise, and vibration experiments at different speeds. The results show that increasing speed leads to a higher pressure difference between the pump chamber and the cooling circuit. Meanwhile, the turbulent kinetic energy at the impeller outlet increases. Despite an increase in energy loss, the loss ratio decreases, and overall efficiency improves. The internal flow noise collected by the outlet hydrophone mainly comes from Rotor–Stator Interference (RSI), and it can sensitively capture changes in rotational speed. The dominant frequency of the outlet noise agrees well with the blade frequency calculated from the set speed, with a maximum deviation of 0.26%. As the speed increases, the overall sound pressure level (OASPL) at the inlet and outlet and the Root Mean Square (RMS) acceleration values at the outlet and pump body generally increase, while the acceleration at the motor base shows a decreasing trend. The conclusions are helpful for the design and optimization of rotary machinery such as high-speed magnetic pumps. Full article

Background: Despite its high vaccination coverage, pertussis remains a public health concern due to waning vaccine-induced immunity and the emergence of pertactin (Prn)-negative strains. Nevertheless, anti-Prn antibodies and memory B cells elicited by vaccinations may contribute to long-term immunity and protection against Prn-positive strains. While most vaccination studies focus on serum antibodies, data on memory B cells remain limited. Methods: In this study, we implemented a flow cytometry-based approach to characterize Prn-specific B-cell fluctuations following Tdap booster vaccination in five healthy adults. Total and Prn- and tetanus toxoid fragment C (TTC)-specific plasma cells and memory B cells were analyzed at baseline and at 7, 14, 21, and 90 days post-vaccination using Prn Klickmers^® and TTC tetramers. Following this, cellular responses were correlated with antigen-specific serum IgG and IgA levels. Results: Prn-specific and TTC-specific memory B cells increased on days 14 and 7 post-vaccination, respectively, accompanied by a phenotypic shift from IgMD+ to IgG+ cells. Clear expansions of total as well as Prn- and TTC-specific plasma cells occurred on day 7. These plasma cells primarily comprised IgG+, but an increase in Prn-specific IgA+ plasma cells was also observed. The numbers of Prn-specific IgG+ memory B cells on day 7 post-vaccination correlated weakly with serum anti-Prn IgG levels at later time points. Conclusion: To our knowledge, this is the first study to use flow cytometry to evaluate Prn-specific B-cell responses and report their fluctuations over time following vaccination. These findings support the potential of this method to complement serological assays and improve our understanding of vaccine-induced immunity. Full article

Maintaining voltage stability and minimizing power losses for remote marine loads powered by long submarine cables is the challenging context of this paper. Flexible Alternating Current Transmission Systems (FACTS) are well-studied for terrestrial grids. However, their comparative performance and efficiency in the context of high-capacity submarine links remain a gap in the literature. This paper presents a rigorous analysis of the performance of a Unified Power Flow Controller (UPFC), Static Synchronous Series Compensator (SSSC), and Thyristor Controlled Series Capacitor (TCSC). A mathematical framework is developed to introduce the “solution circle” concept, which demonstrates that the series impedance values required to maintain a specific load voltage define a circle in the complex plane. A theoretical analysis is performed, revealing that the UPFC, with its two degrees of freedom, is significantly more efficient because it can select the minimum impedance magnitude on this circle. In contrast, SSSC and TCSC are limited to the reactive axis, which, under certain operating conditions, may not cross the solution circle; therefore, they may not meet the power quality objective. The results of a practical case study show that UPFC requires approximately half the rated power (22.4 MVA) compared to its counterparts (39.4 MVA) to achieve the same control objectives. Full article

Deep saline aquifers are key targets for secure CO₂ geological storage because of their petrophysical and geochemical characteristics. This study conducts two-dimensional radial numerical simulations of CO₂–brine flow and dissolution to examine plume migration and dissolution in saline aquifers while allowing porosity and permeability to evolve with pressure. The model outputs include reservoir pressure, porosity, permeability, gas saturation, and dissolved CO₂, with additional analyses of permeability anisotropy, initial reservoir pressure, and stratified sandstone–shale architecture. Simulations with evolving properties predict a smaller radial plume extent than simulations with fixed properties, together with a maximum pressure buildup of about 2 MPa near the injection well. In a homogeneous aquifer, porosity and permeability increase nonlinearly during injection and reach about 1.25 and 2.6 times their initial values near the injection well after 1200 days, whereas the increases are lower in the sandstone–shale case at about 1.16 and 2.0 times because shale interlayers confine the enhanced zone to the lower sandstone. Increasing permeability anisotropy shifts migration toward lateral spreading, and higher initial reservoir pressure reduces plume extent. Overall, the assumption of constant porosity and permeability tends to predict larger plume footprints and different pressure responses, with sensitivity controlled by anisotropy, initial pressure, and shale interlayers. Full article

Long-fiber thermoplastic (LFT) materials are a versatile category of composite materials that can be directly compounded (LFT-D) in twin screw extruders and compression molded. Originating in the automotive sector, the LFT-D process is becoming increasingly attractive for other industries where low cycle times, lightweight performance and recyclability are required. The purpose of this work is to summarize mechanical properties and findings from the investigations into LFT-D process–microstructure–property relationships and present a design of experiments (DoE) study based on the current state of the art. Primary parameters from LFT-D compounding, screw speed, fiber roving amount and polymer throughput m_p are chosen as DoE factors. Polyamide 6 (PA6) is reinforced with a glass fiber (GF) mass fraction w_f between w_f = 20% and w_f = 60%. Tensile, flexural and impact properties are chosen as DoE output parameters, characterized and discussed in relation to the state of the art. The unique microstructure of LFT-D materials, especially the existence of a charge and flow area as well as the fiber migration, is considered in the discussion. All mechanical properties characterized have a linear relation to w_f. This study demonstrates the interactive relationship between the main factors and w_f, which significantly influences the mechanical properties. This dependence of w_f on the DoE factors is accounted for in advanced response contour plots proposed in this work. Parameter recommendations for the screw speed are reported by ranges of w_f and polymer throughput for the goal of maximum mechanical properties or low coefficient of variations. At w_f < 30% a low screw speed is recommended to improve most mechanical properties as well as the coefficient of variation. Full article

The classical Neumann–Kelvin (NK) theory of potential flow around a free-surface-piercing ship that steadily advances in calm water or through regular waves is considered. Specifically, this study presents an elementary ‘no-equation interpretation’ of the rigid-waterplane linear flow model and the related modification of the NK theory recently presented by the authors and complements the detailed mathematical analysis given in that earlier study. Specifically, the NN (Neumann–Noblesse) integral equation obtained in that previous study by applying Green’s fundamental identity to an alternative linear flow model called the rigid-waterplane flow model, in which an open free-surface-piercing ship hull is closed by a rigid waterplane slightly submerged under the free surface, is interpreted in light of Saint-Venant’s principle. Briefly, the present study argues that the NK integral equation obtained in the classical NK theory of potential flow around a ship contains a singularity at the ship waterline and that this singularity is removed—in the spirit of the classical Saint-Venant principle—in the rigid-waterplane flow model and the related weakly-singular NN integral equation, which can then be viewed as a ‘regularization’ of the NK integral equation. This study also presents variants of the NN integral equation in which a function defined in terms of the ship hull surface geometry by an integral over the ship waterplane or an integral around the ship waterline is expressed as equivalent integrals over the ship hull surface. Like the NN integral equation given previously, the equivalent variants of the weakly-singular NN integral equation obtained in this study do not involve a waterline integral and hold for a ship that steadily advances in calm water or through regular waves, as well as for an offshore structure or a moored ship in regular waves. Full article

To address the demand for a micro-power supply for vehicle suspension control, a novel harvester is proposed to recover vortex-induced vibration energy in the wake of a shock absorber. A suspension dynamic model was established to simulate the spring compression process and identify the wind-shielding condition. The spring-shock absorber assembly was then simplified as a stepped cylinder with two cross-sections. Flow-field analysis showed that the size, shape, and rising angle of the wake vortices were affected by the bluff-body geometry, Reynolds number, and boundary conditions. The downwash motion was found to directly influence vortex development, and two new vortex-connection modes were identified. These results provided guidance for harvester optimization. A two-way fluid–structure interaction model was developed to describe the electromechanical conversion behavior of the proposed harvester under flow excitation. Numerical results showed that the output voltage increased with vehicle speed. An average peak voltage of 1.82 V was obtained when the piezoelectric patches were installed two larger-cylinder diameters downstream. The optimal patch length was 120 mm, and further increasing the length did not significantly improve the harvesting performance. Finally, a full-scale prototype was tested, and the measured voltage agreed well with the simulation results. The proposed harvester can therefore serve as a potential micro-power source for low-power suspension electronics. Full article