Horizontal And Vertical Research Articles

Virtual Sound Image Reconstruction Method for Multi-objective Optimization of Folk Music Based on Evolutionary Algorithm

At present, the exchanges in various fields such as culture, economy, and politics are becoming more and more close in the world. From the perspective of the relationship between national music and cultural development, the development of national music has also received more and more attention, and it has become an inevitable trend in the development of today's era. The purpose of this paper was to perform virtual reconstruction of the sound image of folk music through multiple objective optimizations, and to model the virtual sound image of folk music as a multi-objective optimization problem. According to the research on sound image positioning, the relevant noise factors were removed, so as to achieve the playback of ethnic music that enhanced the surround effect and visual enjoyment. The evolutionary algorithm in this paper was mainly based on the multi-objective optimized sound image localization technology. For the music virtual sound image, an improved FCM algorithm and an evolutionary multi-objective optimization algorithm combining local and non-local information of the sound image were proposed, respectively. Through the analysis of the traditional sound image algorithm method, the accuracy of the sound image localization on the horizontal plane could be effectively improved. After the conversion, the audience could feel the better stereo image and surround feeling of the folk music. Through experimental analysis, it can be seen that the system can not only perform virtual conversion of audio-visual signals of different frequencies, but also provide data for different audio playback systems. The feature point registration error is low, and the reconstruction effect is good, especially the random delay processing in the range of 0∼20m, and the performance is better than the traditional method. Finally, virtual left and right surround sound image signals were obtained, which effectively improved the three-dimensional surround feeling of folk music.

Novel Eyelid Supraorbital Pretemporal Approach to the Anterior Communicating Artery Complex: A Quantitative Cadaveric Comparative Study

Abstract Objectives Access to the anterior communicating artery (ACom) complex may be achieved via the modified orbito-zygomatic (mOZ) or eyelid supraorbital (ES) approaches. Further, the ES approach may improve cosmesis at the cost of decreased exposure and maneuverability. Thus, a novel eyelid supraorbital pretemporal (ESP) approach, a combination of the ES approach with a pretemporal dissection, may optimize the shortcomings of the ES approach. Design This is a cadaveric study. Setting Five ES, ESP, and mOZ approaches were performed on cadaveric heads and compared. Participants Cadaveric specimens were provided under the University of Oklahoma Health Science Center's Willed Body Program. Main Outcome Measures Quantitative measures of exposure, maneuverability, and angles of attack in horizontal and vertical planes were compared between approaches. Results The ESP approach was superior in terms of exposure and deep maneuverability when compared with the ES approach (p < 0.01). In addition, this approach demonstrated superior angles of attack in vertical (p < 0.01) and horizontal (p = 0.045) planes. When compared with the mOZ approach, the ESP approach provided significantly greater exposure to the contralateral A2 (p < 0.01) with a less favorable horizontal angle of attack (p < 0.01). The ESP provides exact exposure to complete the pretemporal osteotomy, offering a unique perspective on the ACom complex. Conclusion When accessing the ACom complex, the ESP approach yields superior exposure and maneuverability compared with the ES approach and is comparable to the mOZ approach, with unique advantages provided by the addition of pretemporal osteotomy and dissection.

Cell size and deformation measurement using constrictions integrated into a microfluidic device

In this study, we developed a microfluidic device to evaluate cell size and deformability. As a specific method, a physical pushing load was applied to the cells using a channel having a constriction with a height of 1 μm. In addition, by orienting the constriction in a vertical direction, it was possible to measure the cell area easily using a microscope under load. The system constructed in this study can evaluate the contact area between the cells and the glass surface before and after applying a load under a microscope. The only input parameter was the syringe flow rate, and it was possible to evaluate multiple cells in a cell suspension simultaneously. Also, since the flow rate is 50 μm min−1 or less, there is no need for a high-speed camera. This time, we evaluated cell types with different characteristics: NIH/3T3 and smooth muscle cells (SMC). To evaluate deformability, we focused on the circularity of the cells during load application. Due to the influence of the flow within the channel, cells with high deformability assumed an almost elliptical shape and flowed through the constriction. Using the device developed in this study, we confirmed that SMCs, which are muscle cells, have large variations in cell size and hardness among individual cells. Finally, we discussed these results and possible future applications.

Effectiveness of laser pulsed irradiation for antimicrobial photodynamic therapy

The aim of this study was to compare two types of light irradiation devices for antimicrobial photodynamic therapy (aPDT). A 660-nm light-emitting diode (LED) and a 665-nm laser diode (LD) were used for light irradiation, and 0.1 mg/L TONS 504, a cationic chlorin derivative, was used as the photosensitizer. We evaluated the light attenuation along the vertical and horizontal directions, temperature rise following light irradiation, and aPDT efficacy against Staphylococcus aureus under different conditions: TONS 504 only, light irradiation only, and TONS 504 with either LED (30 J/cm2) or LD light irradiation (continuous: 30 J/cm2; pulsed: 20 J/cm2 at 2/3 duty cycle, 10 J/cm2 at 1/3 duty cycle). Both LED and LD light intensities were inversely proportional to the square of the vertical distance from the irradiated area. Along the horizontal distance from the nadir of the light source, the LED light intensity attenuated according to the cosine quadrature law, while the LD light intensity did not attenuate within the measurable range. Following light irradiation, the temperature rise increased as the TONS 504 concentration increased in the order of pulsed LD < continuous LD < LED irradiation. aPDT with light irradiation only or TONS 504 only had no antimicrobial effect, while aPDT with TONS 504 under continuous or pulsed LD light irradiation provided approximately 3 log reduction at 30 J/cm2 and 20 J/cm2 and approximately 2 log reduction at 10 J/cm2. TONS 504-aPDT under pulsed LD light irradiation provided anti-microbial effect without significant temperature rise.

The accuracy of vehicle position and heading angle improvement based on dual-antenna GNSS/INS/Barometer integration using extended Kalman filter

Abstract In the field of autonomous driving progresses, obtaining the precise position and attitude of vehicles through measurement technology is vital. An integrated GNSS/INS/Barometer (Global Navigation Satellite System/Inertial Navigation System/Barometer) fusion method is proposed to improve vehicle positioning and heading angle accuracy. An extended Kalman filter (EKF) based on horizontal dilution of precision (HDOP) is designed to fuse the INS error and the GNSS measurement. Furthermore, GNSS dual antennas are utilized to increase a state variable in EKF based on HDOP in addition to position and velocity. The kinematic constraint of zero velocity in the lateral and vertical directions of vehicle movement is used to measure the mounting angle to reduce error. The position and heading angle accuracy of the proposed method are 0.483 m and 1.358°, which represent reductions of 37.03% and 43.86% compared to the conventional EKF method, respectively. The experimental results demonstrate that the proposed method can measure accurate position and heading angle in both open and occluded environments.

Incoherent tune measurement of an ion storage ring using single ions

The measurement of betatron tunes is important in the studies of beam dynamics in circular accelerators. Here, we report a new method to extract the fractional tune values using revolution times of single ions stored for a few hundred turns in a heavy-ion storage ring utilizing a single time-of-flight detector. The experiment was done at the experimental Cooler Storage Ring (CSRe) in Lanzhou. The unbunched cocktail secondary beam was injected into the ring and allowed to coast without further excitation. Since the average number of simultaneously stored ions inside the 128.8 m-circumference ring was merely ∼20, the obtained tune values are considered to be incoherent. Given that the revolution time of an individual ion is related to its momentum, the chromaticity of the ring could be addressed. Moreover, the data indicate a possible beam mismatch in vertical direction y^ at the injection into CSRe. The new method is developed for ultralow beam intensities and is thus a sensitive approach to tune measurements. Thanks to its simplicity, the method can straightforwardly be employed at other circular accelerators by applying the same detection approach. Published by the American Physical Society 2024

Specific pelvic shape in patients with developmental dysplasia of the hip on 3D morphometric homologous model analysis.

To clarify the morphological factors of the pelvis in patients with developmental dysplasia of the hip (DDH), three-dimensional (3D) pelvic morphology was analyzed using a template-fitting technique. Three-dimensional pelvic data of 50 patients with DDH (DDH group) and 3D pelvic data of 50 patients without obvious pelvic deformity (Normal group) were used. All patients were female. A template model was created by averaging the normal pelvises into a symmetrical and isotropic mesh. Next, 100 homologous models were generated by fitting the pelvic data of each group of patients to the template model. Principal component analysis was performed on the coordinates of each vertex (15,235 vertices) of the pelvic homologous model. In addition, a receiver-operating characteristic (ROC) curve was calculated from the sensitivity of DDH positivity for each principal component, and principal components for which the area under the curve was significantly large were extracted (p<0.05). Finally, which components of the pelvic morphology frequently seen in DDH patients are related to these extracted principal components was evaluated. The first, third, and sixth principal components showed significantly larger areas under the ROC curves. The morphology indicated by the first principal component was associated with a decrease in coxal inclination in both the coronal and horizontal planes. The third principal component was related to the sacral inclination in the sagittal plane. The sixth principal component was associated with narrowing of the superior part of the pelvis. The most important factor in the difference between normal and DDH pelvises was the change in the coxal angle in both the coronal and horizontal planes. That is, in the anterior and superior views, the normal pelvis is a triangle, whereas in DDH, it was more like a quadrilateral.

Low-defect and stress-free AlN(0001) nanoprisms and microrods selectively grown on micro-patterned c-sapphire substrate by plasma-assisted molecular beam epitaxy

This paper describes different growth modes of AlN layers on micro-cone patterned c-sapphire substrates (μ-PSSs) using plasma-assisted molecular beam epitaxy. Ordered arrays of AlN nanoprisms and microrods were selectively grown on the tips of μ-PSS's microcones according to a bottom-up formation mechanism using sequential migration enhanced and metal-modulated epitaxy (MME) under metal-rich growth conditions at 820 °C. Transmission electron microscopy revealed structurally perfect AlN regions above the tips of the μ-PSSs, which initiate as inverted nanopyramids with {1011¯} side faces, evolving into hexagonal nanoprisms with orientations of {11¯00} and (0001) for side and top surfaces, respectively. The diameter and height of these ordered hexagonal nanoprisms, which have a 60% probability of nucleating, were about 1 μm. Long-term MME growth of these nanoprisms in both vertical and lateral directions led to the formation of AlN(0001) microrods with a maximum possible diameter of two micrometers and a height of up to 6 μm. Atomic force microscopy revealed a mixed step-flow and 2D nucleation growth mechanism for the flat tops of these AlN nanoprisms and microrods with an average surface roughness of 1–2 monolayers. Micro-Raman spectroscopy demonstrated narrow E2 (high) linewidths of 3.8 and 4.2 cm−1 for essentially stress-free AlN nanoprisms and microrods, respectively.

Dynamic channel selection based on vertical sensitivities for the assimilation of FY‐4A geostationary interferometric infrared sounder targeted observations

AbstractTarget observations have garnered significant attention owing to their successful applications in enhancing forecasting skills of extreme weather events, particularly tropical cyclone (TC) events. The key step of implementing target observation is to determine the sensitive area in advance. Previous studies often obtained the sensitive areas for TC forecasting by vertically integrating the energy of optimal perturbation and taking the horizontal area of large energy, in an attempt to use it to represent roughly the sensitivity of the whole atmospheric layer. The advent of the geostationary interferometric infrared sounder on the FY‐4A satellite and then corresponding satellite data assimilation have opened up a new possibility for identifying the vertical sensitivity for TC forecasting to improve the forecasting skill. This article proposes a targeting satellite channel (TSC) approach to accurately capture the sensitivity along vertical directions of the atmosphere that allows one to preferentially select the channels whose observations locate on the sensitive vertical atmospheric layers. Numerical experiments demonstrate that, when preferentially assimilating the channel observations obtained from the TSC approach, the TC tracks achieve a considerably smaller forecast error than the information entropy channel selection approach. The TSC approach, therefore, has the potential for the satellite data assimilation to improve TC track forecasting skill very effectively, which can also provide guidance to targeting observations in field campaigns for TC forecasting.

Toward Building a Virtual Laboratory to Investigate Rainfall Microphysics at Process Scales

Abstract A 3D numerical model was built to serve as a virtual microphysics laboratory (VML) to investigate rainfall microphysical processes. One key goal for the VML is to elucidate the physical basis of warm precipitation processes toward improving existing parameterizations beyond the constraints of past physical experiments. This manuscript presents results from VML simulations of classical tower experiments of raindrop collisional collection and breakup. The simulations capture large raindrop oscillations in shape and velocity in both horizontal and vertical planes and reveal that drop instability increases with diameter due to the weakening of the surface tension compared with the body force. A detailed evaluation against reference experimental datasets of binary collisions over a wide range of drop sizes shows that the VML reproduces collision outcomes well including coalescence, and disk, sheet, and filament breakups. Furthermore, the VML simulations captured spontaneous breakup, and secondary coalescence and breakup. The breakup type, fragment number, and size distribution are analyzed in the context of collision kinetic energy, diameter ratio, and relative position, with a view to capture the dynamic evolution of the vertical microstructure of rainfall in models and to interpret remote sensing measurements. Significance Statement Presently, uncertainty in precipitation estimation and prediction remains one of the grand challenges in water cycle studies. This work presents a detailed 3D simulator to characterize the evolution of drop size distributions (DSDs), without the space and functional constraints of laboratory experiments. The virtual microphysics laboratory (VML) is applied to replicate classical tower experiments from which parameterizations of precipitation processes used presently in weather and climate models and remote sensing algorithms were derived. The results presented demonstrate that the VML is a robust tool to capture DSD dynamics at the scale of individual raindrops (precipitation microphysics). VML will be used to characterize DSD dynamics across scales for environmental conditions and weather regimes for which no measurements are available.

Diffusion characteristics of vertical oxygenic-thermal coupled jet and indoor oxygenic-thermal environment regulation in high-altitude areas

The Qinghai-Tibet Plateau has typical climatic phenomena such as low temperatures and oxygen deficiency, which have a great impact on the health of local residents. In order to improve the indoor oxygenic-thermal environment, this paper explored the flow characteristics of a vertical oxygenic-thermal coupled jet by CFD numerical simulation and experimental verification in high-altitude areas. The results found that the oxygenic-thermal diffusion range moved up by 0.17m–1.02 m in the vertical direction as the jet temperature increased by 3K–9K, and this process could enhance the synergistic effect of the oxygenic-thermal diffusion, while the oxygen flow supply reduced this effect, and the diffusion range shifted down by 0.87m–1.90 m as the jet oxygen concentration increased by 20%–60%. The indoor airflow uniformity with ΔT = 3K was more desirable than that with ΔT = 9K, and a high oxygen concentration was detrimental to temperature elevation, so a slight variation in temperature and concentration could be selected when meeting the demand for indoor heating and oxygen supply. The air inlet position has a more significant effect on the thermal environmental distribution than the oxygen environment, and the coupled airflow non-uniformity coefficient is minimized when the air inlet is located at the top center of the room. This study would provide some recommendations for regulating the indoor oxygenic-thermal environment in high-altitude areas under vertical jet mode.

Eulerian–Lagrangian multiscale numerical analysis of multimodal partial shedding dynamics

The objective of this paper is to investigate the multimodal partial shedding dynamics from a multiscale perspective of cloud cavitating flows under two distinct cavity shedding mechanisms, namely the re-entrant jet mechanism and the shock wave propagation mechanism. A two-way Eulerian–Lagrangian coupling algorithm is applied to capture the multiscale vapor topologies from microbubble to large-scale cavities. The large-scale cavity evolution is solved through large eddy simulations (LES) with the volume of fraction (VOF) method in Eulerian frame. The sub-grid microbubbles are tracked in Lagrangian frame based on the discrete bubble model (DBM) method. The predictions agree well with experimental observation of the periodical cavity evolution and microbubble dynamics under both the re-entrant jet mechanism and shock wave mechanism around a NACA66 hydrofoil. The numerical simulation provides detailed analysis of the cavitating turbulent flow on the microbubble behavior with emphasis on the spatial-temporal distribution characteristics of microbubbles. The results show that the number and mean size of microbubbles in the cavitation region increase gradually with the growth of attached sheet cavity, development of re-entrant jet and collapse of largescale cavity for both cavitation patterns. Meanwhile, microbubbles are mainly distributed on the largescale interfaces where have high value of vorticity and turbulent kinetic energy under the effect of re-entrant jet and vortex structures. And the probability density functions (PDFs) of microbubble exhibit gamma distributions with a dominant peak at approximately 50 μm for both shedding mechanisms. However, the shock wave formation and propagation process only occurs in the final stage of cavitating flow under shock wave mechanism causing the condensation of vapor and the decrease of the number and mean size of microbubbles. Moreover, the microbubbles are uniformly distributed along the streamwise and vertical directions behind shock wave front.

Integration of High-Rate GNSS and Strong Motion Record Based on Sage–Husa Kalman Filter with Adaptive Estimation of Strong Motion Acceleration Noise Uncertainty

A strong motion seismometer is a kind of inertial sensor, and it can record middle- to high-frequency ground accelerations. The double-integration from acceleration to displacement amplifies errors caused by tilt, rotation, hysteresis, non-linear instrument response, and noise. This leads to long-period, non-physical baseline drifts in the integrated displacements. GNSS enables the direct observation of the ground displacements, with an accuracy of several millimeters to centimeters and a sample rate of 1 Hz to 50 Hz. Combining GNSS and a strong motion seismometer, one can obtain an accurate displacement series. Typically, a Kalman filter is adopted to integrate GNSS displacements and strong motion accelerations, using the empirical values of noise uncertainty. Considering that there are significantly different errors introduced by the above-mentioned tilt, rotation, hysteresis, and non-linear instrument response at different stations or at different times at the same station, it is inappropriate to employ a fixed noise uncertainty for strong motion accelerations. In this paper, we present a Sage–Husa Kalman filter, where the noise uncertainty of strong motion acceleration is adaptively estimated, to integrate GNSS and strong motion acceleration for obtaining the displacement series. The performance of the proposed method was validated by a shake table simulation experiment and the GNSS/strong motion co-located stations collected during the 2023 Mw 7.8 and Mw 7.6 earthquake doublet in southeast Turkey. The experimental results show that the proposed method enhances the adaptability to the variation of strong motion accelerometer noise level and improves the precision of integrated displacement series. The displacement derived from the proposed method was up to 28% more accurate than those from the Kalman filter in the shake table test, and the correlation coefficient with respect to the references arrived at 0.99. The application to the earthquake event shows that the proposed method can capture seismic waveforms at a promotion of 46% and 23% in the horizontal and vertical directions, respectively, compared with the results of the Kalman filter.

All inkjet-printed organic solar cells on 3D objects

Drop-on-demand inkjet printing is a promising and commercially relevant technology for producing organic electronic devices of arbitrary shape on a wide variety of different substrates. In this work we transfer the inkjet printing process of organic photovoltaic devices from 2D to 3D substrates, using a 5-axis robot system equipped with a multi-nozzle inkjet printing unit. We present a ready-to-use 3D printing system for industrial application, using a 5-axis motion system controlled by commercial 3D motion software, combined with a commonly used multi-nozzle inkjet print head controlled by the corresponding printing software. The very first time inkjet-printed solar cells on glass/ITO with power conversion efficiencies (PCEs) of up to 7% are realized on a 3D object with surfaces tilted by angles of up to 60° against the horizontal direction. Undesired ink flow during deposition of the inkjet-printed layers was avoided by proper ink formulation. In order to be able to print organic (opto-)electronic devices also on substrates without sputtered indium tin oxide bottom electrode, the bottom electrode was inkjet-printed from silver nanoparticle (AgNP) ink, resulting in the first all inkjet-printed (i.e. including bottom electrode) solar cell on a 3D object ever with a record PCE of 2.5%. This work paves the way for functionalizing even complex objects, such as cars, mobile phones, or ‘Internet of Things’ applications with inkjet-printed (opto-)electronic devices.

True triaxial unloading test on the mechanical behaviors of sandstone: Effects of the intermediate principal stress and structural plane

A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states. The experimental results indicate that the dip angle of structural plane (θ) and the intermediate principal stress (σ2) have an important influence on the peak strength, cracking mode, and rockburst severity. The peak strength exhibits a first increase and then decrease as a function of σ2 for a constant θ. However, when σ2 is constant, the maximum peak strength is obtained at θ of 90°, and the minimum peak strength is obtained at θ of 30° or 45°. For the case of an inclined structural plane, the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase in σ2, while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane, accompanied by a series of tensile cracks besides. The specimens with structural plane do not undergo slabbing failure regardless of θ, and always exhibit composite tensile-shear failure whatever the σ2 value is. With an increase in σ2 and θ, the intensity of the rockburst is consistent with the tendency of the peak strength. By analyzing the relationship between the cohesion (c), internal friction angle (φ), and θ in sandstone specimens, we incorporate θ into the true triaxial unloading strength criterion, and propose a modified linear Mogi-Coulomb criterion. Moreover, the crack propagation mechanism at the tips of structural plane, and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized. This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.

In-cylinder flow evolution in the horizontal plane of a motoring compression ignition engine

This study used the two-dimensional particle image velocimetry technique to quantify the in-cylinder horizontal plane velocity field evolution in a swirl-supported light-duty single-cylinder diesel engine. The data were acquired at a constant engine speed of 1600 revolutions per minute. For each case, the distance of the laser sheet from the fire deck was varied (z = 5, 10, and 20 mm) to investigate the axial variations in the flow field during the flow evolution in the compression stroke. A vortex identification algorithm was used to detect the swirl center and its deviation from the rigid body rotation. A Bessel fit was obtained using the experimental data. The result revealed that the in-cylinder flow was not axisymmetric. The swirl center approached the geometrical center as the piston approached the top dead center. The flow evolved at the farthest plane from the fire deck. The axial diffusion of angular momentum resulted in the formation of the swirl flow structure in the plane closer to the fire deck. Angular momentum analysis of a simplified geometry has been presented to explain the swirl amplification. The estimated results were compared with the experimental results to show the momentum stratification in the engine cylinder later in the compression stroke.

Stability of the coronal magnetic field around large confined and eruptive solar flares

Context. The coronal magnetic field, which overlies the current-carrying field of solar active regions, straps the magnetic configuration below. The characteristics of this overlying field are crucial in determining if a flare will be eruptive and accompanied by a coronal mass ejection (CME), or if it will remain confined without a CME. Aims. In order to improve our understanding of the pre-requisites of eruptive solar flares, we study and compare different measures that characterize the eruptive potential of solar active regions – the critical height of the torus instability (TI) as a local measure and the helicity ratio as a global measure – with the structural properties of the underlying magnetic field, namely the altitude of the center of the current-carrying magnetic structure. Methods. Using time series of 3D optimization-based nonlinear force-free magnetic field models of ten different active regions (ARs) around the time of large solar flares, we determined the altitudes of the current-weighted centers of the non-potential model structures. Based on the potential magnetic field, we inspected the decay index, n, in multiple vertical planes oriented alongside or perpendicular to the flare-relevant polarity inversion line, and estimated the critical height (hcrit) of TI using different thresholds of n. The critical heights were interpreted with respect to the altitudes of the current-weighted centers of the associated non-potential structures, as well as the eruptive character of the associated flares, and the eruptive potential of the host AR, as characterized by the helicity ratio. Results. Our most important findings are that (i) hcrit is more segregated in terms of the flare type than the helicity ratio, and (ii) coronal field configurations with a higher eruptive potential (in terms of the helicity ratio) also appear to be more prone to TI. Furthermore, we find no pronounced differences in the altitudes of the non-potential structures prior to confined and eruptive flares. An aspect that requires further investigation is that, generally, the modeled non-potential structures do not really reside in a torus-instable regime, so the applicability of the chosen nonlinear force-free modeling approach when targeting the structural properties of the coronal magnetic field is unclear.

Large-scale vortex formation in three-dimensional rotating Rayleigh-Bénard convection

Numerical experiments are performed on three-dimensional thermal convection between parallel plates in a rotating system with a larger horizontal region than in previous studies. It is confirmed that a large-scale vortex (LSV) with positive vorticity (cyclonic) is formed over a significant part of the region and its horizontal size increases if the horizontal region is extended. The correlation analysis in the vertical direction shows that the small-scale motion has a typical structure of the baroclinic vortex of thermal convection in the rotating system, whereas the large-scale motion is a barotropic vortex that is not associated with thermal convection. A horizontal spectral analysis of the individual terms in the kinetic energy equation reveals that the nonlinear effect of the small-scale vortex motion caused by the buoyancy force induces a large-scale toroidal component, and that the LSV is maintained by the balance between the nonlinear effect and the viscous dissipation of the large-scale motion. The results of this analysis indicate the importance of kinetic energy damping mechanism for the appearance of LSVs. When weak damping operates at larger scales, it is expected that the maximum extent of the vortex appears even if the horizontal region is extended further. On the other hand, the emergence of LSVs will be prevented when strong enough damping is effective at larger scales.

Characteristics of laser induced plasma near a flat gas-liquid interface and its effect on the performance of laser induced breakdown spectroscopy (LIBS) detection

Moving the laser focus to the vicinity of the gas-liquid interface is the key point for many new enhanced and new methods to improve the quality of spectral signals in water Laser induced breakdown spectroscopy (LIBS) detection. Understanding the generation and evolution characteristics of the plasma induced by pulsed laser near the gas–liquid interface is of great significance for the establishment of evolution models and improvement of these new LIBS methods. In this paper, a set of slow horizontal flow auxiliary system is established to provide an ideal flat gas–liquid two-phase interface experimental condition. Experimental research on vertical incidence flat system was conducted using techniques such as time-resolved imaging, plasma characterization diagnosis, and spectral analysis. And the detection capabilities of the system were also tested. The characteristics and mechanisms of LIBS near the gas-liquid two-phase interface were investigated with the laser incident on the sample along the vertical direction. Simulation of the laser beam focusing process and observation of laser beam spot images show that the shift of plasma generation position relative to the focal point results from the refraction of the laser beam entering the solution from the air and the ‘interface effect’ of propagation on the vertical direction. Moreover, the plasma forms only the optical power density surpasses the breakdown threshold. In this work, plasma with smaller size, rounder shape, stronger radiation, higher temperature, and higher density can be produced when the focus position is in the liquid column 0.3 mm away from the upper interface. Simultaneously, for example, the Mg ion line at 285.213 nm, the obtained spectral intensity to signal-to-background ratio reaches the maximum value, and a better spectral signal can be obtained, which is 2–4 times of other positions, and the detection limits of the elements Na, Mg, and Ca also reach the lowest level, with 1.6–2.4 times of the detection limit of other focusing positions for Mg and 1.4–1.7 times for Ca, respectively.

Heat transfer analysis of Carreau nanofluid flow with gyrotactic microorganisms: A comparative study

Advancement in thermodynamical characteristics of non-Newtonian fluid is achieved by induction of gyrotactic microorganisms in order to attain efficient thermal and mechanical engineering setups, such as micromixers, microfluidic instruments, biosensors and microdevices. So, the primer motive to conduct this research is to examine the effectiveness of gyrotactic microorganisms in managing heat transport in Carreau nanofluid flow over a linearly stretched surface under the effectiveness of opposing and assisting buoyancy forces. Physical aspect of magnetic field along with slip boundary constraint also entertained by employing in vertical direction. The governing equations are modelled in the form of dimensional PDE's and latterly transformed into dimensionless ODEs via similarity transformations. Solution of obtained set of differential system is solved by implementing Runge-Kutta of order 4 and shooting procedure. Visualizations about influence of flow concerning parameters on associated distributions are analyzed in comparative manner for opposing and assisting buoyancy parameter. In addition, metrics for quantities of engineering interest, such as heat and mass fluxes for nano and gyrotactic particles along with skin friction coefficient are calculated in a comprehensive manner.