Volumetric Effects Research Articles

Influence of insulating and conducting walls on magnetohydodynamic flow in a suddenly expanded channel: A numerical study

ABSTRACT In this study, we conducted numerical simulations using the robust code AnuPravaha. The code’s performance was rigorously validated by benchmarking it against a range of standard cases, including Shercliff and Hunt’s cases. The same AnuPravaha code is used to identify the effect of conduction and insulating walls on a suddenly expanded channel for low Hartmann number ranging from 10–100 and Reynolds number ranging from 100–500. The results finding indicate that at a low Hartmann number Ha ≤ 40, the effect on the flow profile remains negligible. As the Hartmann number increases Ha > 40, it generates a more crescent-shaped profile, reducing the centerline flow velocity and increasing it near the side walls. It is also observed that variations in pressure drop are minimal within the low Hartmann number range of Ha = 10–30 but become very significant for a higher Hartmann number (Ha > 30). For a change in Hartmann number from Ha = 20 to Ha = 40, the pressure drop rises by 212% and at Hartmann number from Ha = 50 to Ha = 100, it increases by 284% indicating an amplification effect on the magnetic field at a higher Hartmann number. The pressure drop achieved in Insulating walls is far lesser than the conduction walls as insulating walls don’t allow any current-wall interaction. It is found that by using insulating walls the average pressure drop is reduced by about 94%. At a fixed Reynolds number, insulating walls yield higher outlet velocities than conduction walls due to lower Lorentz force resistance which modifies the volumetric heating effects. Increasing Hartmann number reduces the velocity difference between both types of walls.

Volume Scattering Probability Guiding

Simulating the light transport of volumetric effects poses significant challenges and costs, especially in the presence of heterogeneous volumes. Generating stochastic paths for volume rendering involves multiple decisions, and previous works mainly focused on directional and distance sampling, where the volume scattering probability (VSP), i.e., the probability of scattering inside a volume, is indirectly determined as a byproduct of distance sampling. We demonstrate that direct control over the VSP can significantly improve efficiency and present an unbiased volume rendering algorithm based on an existing resampling framework for precise control over the VSP. Compared to previous state-of-the-art, which can only increase the VSP without guaranteeing to reach the desired value, our method also supports decreasing the VSP. We further present a data-driven guiding framework to efficiently learn and query an approximation of the optimal VSP everywhere in the scene without the need for user control. Our approach can easily be combined with existing path-guiding methods for directional sampling at minimal overhead and shows significant improvements over the state-of-the-art in various complex volumetric lighting scenarios.

Facile synthesis and electrochemical properties of sheet-rod-sheet structured NiCo2S4/EG/Ti3C2Tx nanocomposites

Electrode materials with outstanding stability and electrochemical activity are ideal for high-performance supercapacitors. Herein, we developed a simple two-step method for fabricating NiCo2S4/EG/Ti3C2Tx nanocomposites with a sheet(2D)-rod(1D)-sheet(2D) structure. The NiCo2S4 rods were embedded into the expanded graphite (EG) sheets via an in-situ hydrothermal method, then the Ti3C2Tx sheets were assembled with NiCo2S4/EG by an electrostatic self-assembly method. The obtained NiCo2S4/EG/Ti3C2Tx nanocomposites exhibited a synergistic effect among the components. The addition of EG inhibited the volumetric effect of NiCo2S4 during charging and discharging processes, while the high conductivity of Ti3C2Tx promoted charges transfer. The rod-like structure of NiCo2S4 effectively inhibited the self-stacking of Ti3C2Tx sheets. Consequently, the optimized composite exhibited an excellent specific capacitance of 1837.9 F·g−1 at a current density of 1 A·g−1. Additionally, the composite electrode exhibited a capacitance retention of 73.5 % during 10,000 charging-discharging cycles at a current density of 20 A·g−1.

The Effect of Hydrate Formation Conditions on the Mechanics of Laboratory Methane Hydrate‐Bearing Sediments

AbstractThe mechanics of methane hydrate‐bearing sediments (MHBS) have been broadly investigated over recent years in the context of methane‐gas production or climate‐change effects. Their mechanical investigation has mainly been carried out using models constructed from experimental data obtained for laboratory‐formed MHBS. Along with the dominant effects of hydrate saturation and morphology within the host soil pores, this study recognizes the effective pressure at which the hydrate is formed as a key factor in the MHBS mechanics. A state‐of‐the‐art experimental study has been conducted in order to isolate the effect of the hydrate formation pressure, for use as a model parameter. Two generalized mechanical prediction models that incorporate the effect of the hydrate formation pressure are developed in this work: (a) an analytical shear strength prediction, and (b) an empiric graphical model for predicting volumetric changes along a given stress path. The models are related to a novel data representation which enables the analysis of a few individual test outcomes as a whole, through a volume‐change mapping that describes the complex influence of the volumetric effect of hydrate in MHBS, under combined hydrostatic and deviatoric loading scenarios. In this study, we delve into a specific configuration of hydrate morphology, hydrate saturation, and host soil type, enabling a distinctive fundamental geotechnical investigation and the development of a conceptual modeling approach. The paper describes the approaches by which the MHBS properties can be extracted for other MHBS samples (than those examined in this work) having different host soils and hydrate pore‐space morphologies.

Performance assessment of residential heat pumps operating in extreme cold climates using zeotropic mixtures

Extremely cold climates subject residential heat pumps to significant temperature differences between the heat source and the ambient being heated, which may lead to system failure and reduced compressor performance. The present study considers the possibility of improving the performance of heat pump systems that are simultaneously used for residential space and domestic water heating while subjected to climates varying from -25 °C to 5 °C by exploring the use of zeotropic mixtures. CO2-based binary mixtures composed of low-GWP (global warming potential) refrigerants are considered – R32, R1234yf, and R290 – aiming to benefit from environmentally friendly and flame suppressants characteristics of CO2, as well as the improved thermal efficiency granted by the addition of a secondary refrigerant. A thermodynamic model was developed for a standard vapor-compression heat pump cycle and used to maximize the coefficient of performance limited by the minimum pinch point in the heat exchangers. Our analysis explores the effect of several parameters, such as, the mixture components, mass fractions, space and water heating demands, and heat source temperature on the heat pump's performance. For cold climates, the mixture of R32 (90%)/CO2 (10%) yields the highest COP and CO2-rich mixtures exhibit the lowest. However, by increasing the mass fraction of CO2 within the zeotropic mixture, the pressure ratio of the heat pump was improved. When considering combined performance criteria, such as the volumetric heating effect and the total heat delivered related to heat pump size, CO2-rich mixtures tend to allow more compact systems, especially in colder climates.

Pengaruh Tinggi Bukaan Katup terhadap Torsi dan Daya pada Motor Besin 4 Langkah Berkapasitas 200CC

Automobiles are now the primary mode of transportation due to rapid technological advancements. One method for accomplishing ideal volumetric effectiveness and augment power is to change the camshaft. This study means to grow understanding in the auto world in regards to power and force and to assess the impact of changes in camshaft lift level on a 200cc limit bike utilizing pertalite fuel. The information from the review is introduced in tables and examined utilizing the two-way ANOVA technique and charts. The results of the analysis indicate that a comparison of the power data obtained by adding the lift height (test 3) yields a result of 16 66 HP at 8500 RPM. In the mean time, the force information demonstrates the way that the force examination of the three tests can be supposed to be the most elevated information of the three tests, to be specific (test 3) which is completed by adding a high lift to get a force of 17 59 Nm at engine rotation 5000 RPM. Utilized DeepL.com (free version) for translation.

Abstract P231: Self-administration of Remifentanil Induces Endothelial Dysfunction in Thoracic Aorta and Impaired Cavernosal Reactivity of Wistar Rats

Aims: Recent studies have implicated the use of prescription opioids as a risk factor for cardiovascular diseases (CVD), with associations including myocardial infarction, coronary artery disease and vascular deterioration. Further, opioid-dependent patients show increased vascular aging and arterial stiffness when compared to opioid-naïve controls. Our hypothesis was that rats dependent on remifentanil (a fentanyl analog) after a 12-day operant self-administration (SA) study lead to vascular dysfunction in thoracic aorta. Because erectile dysfunction (ED) is associated with arterial stiffness and is positively correlated with its severity, we hypothesized that opioid SA impaired corpus cavernosum (CC) reactivity as well. Methods: Male Wistar rats (12 weeks-old) were implanted with intravenous catheters and learned to lever press (FR1) for remifentanil (1µg/kg/infusion). A separate group of rats received passive yoked infusions of saline administered in synchrony with remifentanil-treated animals to control volumetric vascular effects. Following administration, animals were euthanized, and aorta and CC collected to evaluate function using both pin and strip myographs. Concentration-response curves to phenylephrine (Phe; 10 -11 -10 -4 M), sodium nitroprusside (SNP) and acetylcholine (Ach or SNP; 10 -10 -10 -4 M) were performed to test contractility and endothelium-independent and -dependent relaxation respectively. Results: Remifentanil-treated rats showed rapidly acquired SA behavior, exhibiting robust and selective drug-paired lever pressing when compared to the non-drug paired lever. In contrast, yoked saline-treated controls rarely exhibited lever pressing. Endothelium-dependent relaxation in the aorta was diminished in the remifentanil group (Rmax: Control: 68.7±2.7 vs. Remi: 47.8±3.7%; p<0.05). There were no observed alterations in endothelium-independent relaxation or vascular contraction. However, CC contraction was slightly shifted to the right in remifentanil treated rats (pEC 50 : Control: 6.04±0.09 vs. Remi: 5.66±0.12; p<0.05). No changes were observed in the CC relaxant response. These findings indicate that 12 days of remifentanil administration results in endothelial dysfunction in large arteries and impaired cavernosal reactivity. Long-term exposure may lead to aortic stiffness exacerbating ED severity and increases in pulse-wave velocity in opioid-dependent patients contributing to the onset of hypertension.

Temperature and volumetric effects on structural and dielectric properties of hybrid perovskites

Three-dimensional organic-inorganic perovskites are rapidly evolving materials with diverse applications. This study focuses on their two representatives - acetamidinium manganese(II) formate (AceMn) and formamidinium manganese(II) formate (FMDMn) – subjected to varying temperature and pressure. We show that AceMn undergoes atypical pressure-induced structural transformations at room temperature, increasing the symmetry from ambient-pressure P21/n phase II to the high-pressure Pbca phase III. In turn, FMDMn in its C2/c phase II displays temperature- and pressure-induced ordering of cage cations that proceeds without changing the phase symmetry or energy barriers. The FMD+ cations do not order under constant volume across the pressure-temperature plane, despite similar pressure and temperature evolution of the unit-cell parameters. Temperature and pressure affect the cage cations differently, which is particularly pronounced in their relaxation dynamics seen by dielectric spectroscopy. Their motion require a rearrangement of the metal-formate framework, resulting in the energy and volumetric barriers defined by temperature-independent activation energy and activation volume parameters. As this process is phonon-assisted, the relaxation time is strongly temperature-dependent. Consequently, relaxation times do not scale with unit-cell volume nor H-bond lengths in formates, offering the possibility of tuning their electronic properties by external stimuli (like temperature or pressure) even without any structural changes.

Gd Metal-Organic Framework Thin Film for On-Chip Local Magnetic Refrigeration.

Dense metal-organic frameworks with high spin paramagnetic nodes are competitive materials for cryogenic magnetic refrigeration, particularly in applications for which local cooling is advantageous. We focus on obtaining thin films of gadolinium formate, which has a large volumetric magnetocaloric effect. Continuous and homogeneous deposits of gadolinium formate are successfully formed on silicon by means of aerosol jet printing, with control over the film thickness from 0.35 μm up to 2.5 μm. The excellent cooling power of the deposits is evidenced via direct measurements of the cooling of a 200 μm silicon wafer down to sub-K temperatures by a single demagnetization from 1 T and 2 K, thereby demonstrating the potential of this approach for on-chip local magnetic refrigeration.

Recovering 3D salt dome by gravity data inversion using ResU-Net++

In geophysical research, gravity-based inversion is essential for identifying geologic anomalies, mapping rock structures, and extracting resources such as oil and minerals. However, traditional gravity inversion methods face challenges, such as the volumetric effects of gravity fields and the management of large complex matrices. Unsupervised learning techniques often struggle with overfitting and interpreting gravity data. This study explores the application of various U-Net-based network architectures in gravity inversion, each offering distinct challenges and advantages. Nested U-Net, although effective, requires a high parameter count, leading to extended training periods. The recurrent residual U-Net’s implicit attention mechanism restricts its dynamic adaptability, whereas the attention U-Net’s lack of residual connections raises concerns about gradient issues. This research comprehensively analyzes the training processes, core functionalities, and module distribution of these networks, including the residual U-Net++. Our synthetic studies compare these networks with traditional focused regularized gravity inversion for reconstructing density anomalies. The results demonstrate that the nested U-Net closely approximates the actual model despite some redundancy. The recurrent residual U-Net indicates an improved alignment with minimal redundancies, and the attention U-Net is effective in density prediction but encounters difficulties in areas of low density. Notably, the residual U-Net++ excels in inversion modeling, achieving the lowest misfit percentage and accurately replicating density values. In practical applications, the residual U-Net++ impressively reconstructs the F2 salt diapir in the Nordkapp Basin with well-defined boundaries that closely match seismic data interpretations. These results underscore the capabilities of the residual U-Net++ in geophysical data analysis, structural reconstruction, and inversion, demonstrating its effectiveness in simulated settings and real-world scenarios.

Understanding the Processing Quality Problem for Cutting Ceramic Materials Using the Thermal-Controlled Fracture Method Induced by a Single-Surface Heat Source.

The thermal-controlled fracture method has been increasingly focused upon in the high-quality cutting of advanced ceramic materials due to its excellent characteristics. The successful application of this method in cutting ceramics mainly depends on the volumetric heating effect. However, most ceramics are treated using the surface heating mode. For the surface heating mode, the processing quality, including fracture trajectory and fracture quality, is far lower than the industrial application standards. This work was conducted to reveal the mechanism of this processing quality. Experiments involving cutting ceramics in single-surface heating mode indicate that the fracture trajectories of the upper and lower surfaces display a significant inconsistency, and the fracture quality is worse than that using the dual-surface heating mode. A cutting model was established to calculate the thermal stress distribution and to simulate the crack-propagation behaviors. The simulation results show good agreement with the experiment and provide the stress distribution, and are used to understand the reason for the processing quality problem. The mechanism of the trajectory deviation and uneven distribution of the fracture quality is revealed based on the simulation and calculation results. This study helps provide a deep understanding of the processing problems arising from this method and thus helps to innovate high-quality processing methods in this field.

Taming the anchor and conversion of polyselenides with a self-reinforcing host in lithium–selenium batteries

Energy-dense lithium–selenium (Li–Se) batteries have attracted increasing attention, while their practical application is still hindered, highly relating to the volume expansion and shuttle of Li polyselenides (LiPSes). Herein, a concurrent anchoring/converting strategy is proposed to restrain the dissolution and realize the rapid conversion of LiPSes. A prototypical regulator comprises of polar catalysts embedded in the interconnected porous muti-walled carbon network (i.e., CoSnO3 nanocubes/CNTs), which promises fast electron/ion transportation and inhibits volumetric effect. Moreover, CoSnO3 as redox accelerator enables the stretched Se−Se bonds to decrease the LiPSes bidirectional conversion barrier, achieving accelerated reaction kinetics. Consequently, the self-reinforcing optimized cathode exhibits superior initial capacity of 730 mAh/g, greatly enlarged capacity after 200 cycles (increase by ∼ 32 % than that of the cell with CNTs), and superior rate capacity (153 mAh/g at 2C). This work uncovers the roles of electronic/ionic conductivity and adsorption/catalysis in Li–Se batteries, providing a guidance for taming the utilization and kinetics of cathode from material perspectives.

On the Origin of the Photoplethysmography Signal: Modeling of Volumetric and Aggregation Effects

This study aimed to examine the mechanisms of the photoplethysmography (PPG) signal formation using Monte Carlo simulations of light transport in biological tissues and experimental observations. Based on a three-layer skin model in backscattering geometry, we sequentially simulated volumetric blood changes and the aggregation/disaggregation of erythrocytes in the dermal layer and estimated their contribution to the registered PPG signal. The calculations were conducted for two wavelengths: 525 nm and 810 nm. For green light, absorption predominates over scattering in the formation of a PPG signal, whereas, for near-infrared light, scattering prevails over absorption. This theoretical result was verified using the Modified Beer–Lambert law and clinical in vivo PPG data of seven healthy subjects. Changes in the size of the scatterers during erythrocyte aggregation and disaggregation can significantly contribute to the PPG signal at near-infrared light. Thus, for the green waveband, the classical volumetric model can be considered dominant in the PPG signal formation. In contrast, for the near-infrared range, both volumetric and aggregation effects must be considered as being approximately equal.

Stabilizing the Si/C blend anode by a multifunctional ternary composite binder

Si/C blend anodes hold great promise in commercialized high-energy-density (HED) Li-ion batteries but suffer from volumetric effects and electrode integrity deterioration. This study reports a ternary composite binder consisting of carboxymethyl cellulose (CMC), cationic polyacrylamide (CPAM), and styrene-butadiene rubber (SBR), which can significantly improve the cyclability of a Si@C/graphite blend anode. A high capacity retention of 92.9% after 100 cycles was achieved in a half cell. Moreover, the ternary binder proves suitable for a very high mass loading (4.9 mAh/g) electrode and is effective in a 2 Ah-level full cell, which delivers an excellent capacity retention of 80.6% after 500 cycles. The beneficial effects were ascribed to the multifunctional groups compatible with the surfaces of both Si and carbon, and the designed rigidness and elasticity which restricts and accommodates the volumetric effects of the Si/C blend anode simultaneously.

FaceFolds: Meshed Radiance Manifolds for Efficient Volumetric Rendering of Dynamic Faces

3D rendering of dynamic face captures is a challenging problem, and it demands improvements on several fronts---photorealism, efficiency, compatibility, and configurability. We present a novel representation that enables high-quality volumetric rendering of an actor's dynamic facial performances with minimal compute and memory footprint. It runs natively on commodity graphics soft- and hardware, and allows for a graceful trade-off between quality and efficiency. Our method utilizes recent advances in neural rendering, particularly learning discrete radiance manifolds to sparsely sample the scene to model volumetric effects. We achieve efficient modeling by learning a single set of manifolds for the entire dynamic sequence, while implicitly modeling appearance changes as temporal canonical texture. We export a single layered mesh and view-independent RGBA texture video that is compatible with legacy graphics renderers without additional ML integration. We demonstrate our method by rendering dynamic face captures of real actors in a game engine, at comparable photorealism to state-of-the-art neural rendering techniques at previously unseen frame rates.

Development of Si-Based Anodes for All-Solid-State Li-Ion Batteries

All-solid-state Li-ion batteries (ASSBs) promise higher safety and energy density than conventional liquid electrolyte-based Li-ion batteries (LIBs). Silicon (Si) is considered one of the most promising anode materials due to its high specific capacity (3590 mAh g−1) but suffers from poor cycling performance because of large volumetric effects leading to particle pulverization, unstable solid electrolyte interphase (SEI), and electric disconnection. In ASSBs, additional issues such as poor solid–solid contacts and interfacial side reactions between Si and solid-state electrolytes (SSEs) are also hindering their practical application. This review first outlines the prospects and recent research achievements of Si-based anodes with special focuses on various Si structures and composite materials, then analyzes the issues of electrochemical–mechanical effects, and finally summarizes key factors and promising strategies for further improving Si-based anodes for high-performance ASSBs.

Efficient Ionic Conductor Anode Materials with Heterojunction Structure of MnOx/Si@C Utilized in Lithium‐Ion Batteries

AbstractThe rapid development of alternative energy vehicles has raised higher requirements for electrode materials. Silicon, with superhigh specific capacity, is highly anticipated in the field of lithium‐ion batteries (LIBs). Unfortunately, the original drawbacks of serious volumetric effect and poor conductivity have confined its commercial steps severely. Herein, a novel composite, based on submicron silicon flakes embedded into carbon shell, with heterojunction‐bearing MnOx nanoparticles, is designed and synthesized successfully via sanding process and in situ thermal reduction methods. The results of electrochemical performance tests and related fitting data show that the presence of MnOx particles facilitates rapid Li+ transport and reduces the impedance associated with Li+ diffusion from the surface to the inner core of the MnOx/Si@C material. The two‐dimensional (2D) silicon flakes and uniform carbon shell have positive influence on structural stability and electronic conductivity. Benefit from the rational design, the optimized MnOx/Si@C composite delivers an outstanding cycling stability of 1106.59 mAh·g−1 at 1 A·g−1 over 1000 cycles with a capacity retention of 71.09%. Besides, the goal material possesses a lithium‐ion diffusion coefficient of ≈1.04×10−9 cm2·s−1. This work provides a reference for the mass preparation of advanced anode materials for lithium‐ion batteries.

Volumetric effect of shunt adjustments in normal pressure hydrocephalus: a randomized, double-blind trial.

MRI volumetry could be used as an alternative to invasive tests of shunt function. In this study, the authors aimed to assess the difference in ventricular volume (VV) before and after surgery and at different performance levels (PLs) of the shunt. This study was a randomized, double-blind trial with a crossover design. The study sample consisted of 36 patients (25 men, 11 women) with a median age of 76 years. All patients had idiopathic normal pressure hydrocephalus (iNPH) and received a Strata shunt at the regional hospital in Östersund, Sweden, with an initial PL of 1.5. Participants underwent MRI with volumetric sequences before surgery and four times postoperatively: at 1 month before randomization to either PL 1.0 (n = 15) or 2.5 (n = 17); at 2 months before crossover to PL 2.5 or 1.0; at 3 months before lowering the PL to 0.5; and finally, at 3 months and 1 day after surgery before resetting the PL to 1.5. VV was measured semiautomatically using quantitative MRI. Both the patient and the examiner of clinical tests and volumetry were blinded to the PL. VV changed significantly between the presurgical level (median 129 ml) and the different shunt settings, i.e., PL 1.0 (median 115 ml), 1.5 (median 120 ml), and 2.5 (median 128 ml; p < 0.001). A unidirectional change in VV was observed for all participants between PL 1.0 and PL 2.5 (median 12 ml, range 2.1-40.7 ml, p < 0.001). No significant change was noted in VV after 24 hours at PL 0.5. Eight participants had asymptomatic subdural effusions at PL 1.0. The consistent decrease in VV after shunt surgery and between PL 2.5 and 1.0 supports the idea that MRI volumetry could be a noninvasive method for evaluating shunt function in iNPH, preventing unnecessary shunt revisions. However, further studies on retest variability of VV as well as verification against advanced testing of shunt function are needed before a clinical implementation of this method can be performed. Clinical trial registration no.: NCT04599153 (ClinicalTrials.gov).

DiagPara: Volumetric parameterization with energy-minimizing pair of diagonal surfaces from given boundaries

An efficient approach for constructing volumetric parameterization with internal energy-minimizing pair of diagonal surfaces from given boundaries is presented. The expression for the internal energy of one diagonal surface pair is formulated. Then necessary and sufficient conditions for trivariate tensor-product Bézier volume with minimal internal energy of the diagonal surface pair are derived. From the derived conditions, an efficient construction algorithm for single- and multi-block Bézier volumes with minimal diagonal internal energy by the Lagrange multiplier method is presented. The auxiliary linear system only needs to be solved once. As soon the explicit computation masks are obtained, the interior control points of the volume are then directly calculated. Experimental results are given to illustrate the volumetric parameterization effects of the presented approach.

Electrophile-mediated ionic liquid strategy for transforming inert natural polymers into highly active iodine adsorbents

The separation and conversion of gas resources are crucial aspects of sustainable energy development. Developing general methods to overcome bottlenecks in gas adsorption and conversion within natural polymers is an urgent global concern. In this work, the use of ionic liquids as electrophiles was proposed, and the Ionic Liquid Solution Process (ILSP) was employed to prepare alginate polymers-based on natural polymers. ILSP achieved a remarkable 0-to-1 transformation in gaseous iodine adsorption, converting inactive alginic acid (∼0 g g−1 in saturated adsorption capacity) into a highly active iodine adsorbent (5.24 g g−1). It was revealed that electrophiles effectively regulated the electron cloud distribution of functional groups by replacing acidic protons on alginic acid, exerting a volumetric effect. This increased the electron density near the deprotonated carboxylic groups, enhancing the nucleophilicity of carboxylic groups. Consequently, it promoted halogen interaction between electron-rich oxygen atoms and iodine during adsorption, thereby improving the efficiency of charge transfer complex formation and polyiodide ion conversion. The ILSP strategy could provide guidance for the separation and conversion of gases such as iodine, carbon dioxide, and hydrogen.