Inclination Research Articles

Negative Poisson’s ratio anchor cable support for fault tunnels with different inclination angles under earthquake

Negative Poisson’s ratio anchor cable support for fault tunnels with different inclination angles under earthquake

Characteristics of induced magnetic field on the time-dependent MHD nanofluid flow through parallel plates

Abstract The heat transfer characteristics of an unsteady magnetohydrodynamic flow through non-conducting infinite vertical parallel plates are presented in this investigation. The flow is subjected to an induced magnetic field, and the base fluid water contains carbon nanotubes (CNTs), in particular multi-wall carbon nanotubes, to present the behaviour of the nanofluid. The aim is to examine the effect of the applied magnetization and CNT concentration on the heat transport performance of the system. However, suitable transformation rules are adopted for the re-designing of the proposed design model into its non-dimensional form. This transformed system is then solved analytically following the standard transformations. The influence of key parameters, including the Hartmann number (Ha), the angle of inclination of the magnetic field, thermal buoyancy, heat source, and the concentration of CNTs in the nanofluid, on the flow phenomena is analysed. The consequences reveal that the occurrence of the inclined magnetic field affects the flow and heat transfer characteristics significantly. Additionally, the introduction of CNTs to the nanofluid enhances the heat transfer performance due to their unique thermal properties. The study demonstrates that enhanced Ha and CNT concentration augments the heat transfer rate.

Thermal and flow dynamics of an inclined air heat exchanger equipped with spring turbulators in the transition flow regime

AbstractThe research involves an experimental investigation into the performance of a flow assisting air heat exchanger under varying angular orientation and uniform external heat fluxes without and with spring turbulators. The investigation was performed for Reynolds numbers ranging from 511 to 9676 and inclination angle 15° and 30°. Three heat fluxes (2, 3, and 4 kW/m2) were applied to the test section to investigate the effect of external surface heating on the range of transition flow regime and thermohydraulic performance. Transition from laminar to turbulent flow for plain channel at different heat fluxes and inclinations occurs within specific Reynolds number ranges: 2436–4446 for 15° inclination at 4 kW/m2, 2574–4289 at 3 kW/m2, and 2850–4152 at 2 kW/m2; for 30° inclination, the ranges are 2518–4151, 2712–4361, and 2992–4346 at the respective heat fluxes. When it comes to the effect of inclination on Nusselt number, the transition occurs sooner at lower angles, but is delayed as the angle increases. Additionally, the Nusselt number decreases as the angle of inclination increases. When comparing the Nusselt numbers of plain tubes to those with spring turbulators, the latter shows a significantly greater enhancement. In laminar flow, a maximum 100% deviation exists between highest and lowest friction factors, decreasing to 75% with increasing Reynolds number; all insert configurations exhibit highest friction factor at 15° due to stronger buoyancy forces.

Morphometric evaluation of the proximal tibiofibular joint among patients with knee joint pain: A pilot study and literature review

Objectives: The proximal tibiofibular joint (PTFJ) serves as a crucial stabilizing component of the entire knee joint complex. Morphometric analysis of the PTFJ can lead to clinically significant conclusions for orthopedic specialists and physiotherapists. The aim of the study was to assess the values of the inclination angle of the PTFJ in the sagittal and coronal planes using magnetic resonance imaging in patients with knee pain. Material and Methods: Measurements of the inclination angle were conducted on 48 patients divided into three groups: Those with damaged medial meniscus (M), those with knee joint cartilage damage (Ca), and the control group (C), in which no deviations from normality were observed in the analyzed imaging study. Results: The mean values of the tibiofibular joint inclination angle in the frontal plane were as follows: (C) 16.927° ± 1.778; (Ca) 16.822° ± 2.537; (M) 14.958° ± 1.760. In the sagittal plane, the corresponding values were: (C) 38.155° ± 1.524; (Ca) 39.392° ± 1.927; (M) 37.471° ± 1.165. Although the mean tibiofibular joint inclination angle was lowest in the group with medial meniscus injury when compared to the control group, these differences did not reach statistical significance. Conclusion: Measuring and observing the variety of PTFJ inclination angles among patients are conducive to better understanding its influence on knee pain. The differences in the PTFJ inclination angle between groups in our pilot study were not statistically significant. Consequently, the study necessitates replication within a substantial population cohort.

Skeletal Anchorage as a Therapeutic Alternative for Mandibular Second Molar Impaction: A Prospective Case–Control Study

Background: The treatment of mandibular second molar (MM2) impaction presents a challenge for orthodontists and requires a surgical–orthodontic approach. This study aims to compare the effectiveness of two techniques for treating impacted MM2: a traditional technique using brass wire and a technique employing skeletal anchorage. Methods: Twelve MM2 with mesio-angular impaction, with an inclination angle between 25° and 40° and an impaction depth between 4 and 10 mm, were selected and randomly divided into two treatment groups. Patients in Group A were treated using the traditional brass wire technique, while those in Group B underwent treatment with a skeletal anchoring technique that utilized a miniscrew positioned in the retromolar region and an elastic sling chain. For both groups, treatment time and the influence of the disimpaction technique on oral health-related quality of life (OHRQoL) were evaluated using the short-form Oral Health Impact Profile (OHIP-14). Results: The results indicated an average treatment time of 168.67 ± 52.32 days for Group A and 76 ± 10.17 days for Group B, with a statistically significant difference (p-value = 0.0002). Regarding the impact on the patients’ OHRQoL, Student’s t-test did not reveal a statistically significant difference between the two groups at 3 and 7 days of follow-up. Conclusions: Both techniques are considered effective for the treatment of impacted MM2 (angulation 25–40°, depth 4–10 mm). The use of skeletal anchorage significantly reduces treatment times without negatively affecting OHRQoL. The results of this study should be confirmed by further studies with larger sample sizes.

STRUCTURAL FEATURES OF DRILLING EQUIPMENT COMPONENTS USING MATERIALS WITH THERMOELASTIC PHASE TRANSFORMATIONS

Alloys exhibiting thermoelastic phase transformations are increasingly being used in various industries. This is due to their shape memory effect and the phenomenon of pseudoelasticity (superelasticity), which can significantly improve the performance of various technical systems. Equipment for drilling oil and gas wells is one of the most demanding in terms of reliability and service life, in connection with which the gradual introduction of the above-described intelligent materials and the phenomena they manifest in the oil and gas industry began. This article analyzes the developed design and proposes methods of mounting/dismounting roller bit elements made according to the proposed design using an alloy with thermoelastic phase transformations, namely the shape memory effect, and compares them with existing designs. Computational studies and computational analysis of the design of the fastening of drilling equipment elements using the Solid Works program and the Solid Works Simulation module were carried out, which showed significant advantages of the proposed method when applying the shape memory effect as a method of geometric fixation during installation compared to interference fit. Tests were also carried out on the IR-200-0 breaking machine in order to verify and confirm the theoretical results obtained using special equipment, with the use of which the reliability of fixation due to the intermediate bushing with taper was determined. As an example, sleeves with an inclination angle to the axis of the cone of 3 degrees were made, fixed in the hole with a reverse taper with a response angle of inclination. The tests confirmed the assumptions made and the results obtained in the course of theoretical calculations and computer modeling, showing that even in the martensitic state this alloy fixes the teeth in special holes of the rolling cutter more reliably compared to the interference fit, which, in turn, makes it possible to conclude that it is advisable to use the proposed installation method, which gives obvious advantages over existing ones.

Evaluation study of solar powered public street lighting as battery charging at Islamic Center based on PSIM

Electrical energy is essential for the growth and advancement of technological knowledge that continues to increase. Solar cells are devices that convert solar energy through photovoltaic devices. Solar cell public street lighting (PJUBS) uses unlimited and free solar energy, is a feasible and cheap alternative to providing electric lighting. The Islamic center mosque is one of the places of worship for the majority of Muslims in the city of Lhokseumawe using public street lighting to support public security and safety. Installation of lamps for lighting is installed at several points, namely right, left or in the middle of the road, as needed, including flyovers, underpasses, and bridges. Public street lighting that is efficient and environmentally friendly is in accordance with SNI 7391: 2008. In this study, the lamps used in this evaluation study are solar types with a power of 50 Watts. The calculation results show that the illumination produced at the end of the road when using a 50 Watt solar LED lamp is 0.29 lux so that this does not comply with the provisions of BSN SNI 7391: 2008. This condition is influenced by several factors, namely surface temperature, shadows, inclination angle, light intensity, irradiation, and the condition of the panel surface in order to maximize the conversion value of sunlight into electrical energy

Enhancing Oxygen-Dissolving Capacity of Rotary Drum Food Waste Composting: Tumbling Process Optimization and Experimental Validation with Discrete and Finite Element Methods

An optimized tumbling process can significantly improve the oxygen dissolving capacity of composting and fertilizer quality: by increasing the fluffiness of the lower layer of the pile, localized anaerobic fermentation can be avoided, thereby enhancing compost quality. This paper presents a method for improving the oxygen dissolving capacity of rotary drum food waste composting through a combination of simulation optimization and experimental validation. First, the discrete element method was used to optimize the key parameters of the tumbling process. The response surface method was then employed to analyze the composting test results and determine the optimal conditions. To ensure the reliability of the equipment under this method, failure risk analysis was conducted using the finite element method. The simulation optimization results showed that with a rotary drum reactor speed of 3.5 r/min, a horizontal angle of inclination of 2.5°, a mixing blade angle of inclination of 43°, and a blade pitch of 580 mm, the fluffiness of the lower layer of the pile increased by 8.515%, achieving the best tumbling and indirectly enhancing oxygen dissolving capacity. The maximum deformation of the load-bearing components was only 0.0548 mm, and the minimum safety factor was 4.408 (≥1 is considered safe). A 14-day composting experiment was conducted to validate the optimized parameters. The results showed that the maximum temperature of the compost pile reached 68.34 °C (lasting 7 days), with the pH, moisture content, C/N ratio, humus substances, humic acid, and fulvic acid contents of the fertilizer all meeting or exceeding the levels recommended by Chinese national standards. These findings indicate that the optimized tumbling device effectively improved the stability and dissolved oxygen efficiency of food waste composting, providing valuable practical insights and a research foundation for enhancing oxygen efficiency in the composting of other organic wastes.

Fabrication and electroadhesion properties of parylene-coated carbon fiber arrays

Parylene-coated carbon fiber (CF) arrays with tunable inclination angles and heights were fabricated using oxygen plasma etching of composite wafers with embedded parallel CFs, followed by parylene coating via chemical vapor deposition. The effective elastic modulus of the CF arrays was found to decrease approximately in proportion to the square of the fiber length (5-60μm), with the parylene coating (∼2μm) further slightly reducing the modulus. Both experimental measurements and finite element simulations indicated that CF arrays with inclination angles below 75° exhibit ideal contact with glass wafers during electrostatic adhesion. However, the measured electrostatic adhesion between CF arrays and A4 paper was significantly lower than the predicted value for ideal contact, likely due to the porous nature of the paper. Electrostatic chuck prototypes based on the parylene-coated CF arrays demonstrated effective pick-and-place capabilities for A4 paper, plastic films, and glass wafers at voltages ranging from 500 to 900 V, without causing surface damage or leaving residue. These results highlight the potential of the parylene-coated CF arrays for applications in high-precision manufacturing and automated handling systems.

Diffusion-driven flows in a nonlinear stratified fluid layer

Diffusion-driven flow is a boundary layer flow arising from the interplay of gravity and diffusion in density-stratified fluids when a gravitational field is non-parallel to an impermeable solid boundary. This study investigates diffusion-driven flow within a nonlinearly density-stratified fluid confined between two tilted parallel walls. We introduce an asymptotic expansion inspired by the centre manifold theory, where quantities are expanded in terms of derivatives of the cross-sectional averaged stratified scalar (such as salinity or temperature). This technique provides accurate approximations for velocity, density and pressure fields. Furthermore, we derive an evolution equation describing the cross-sectional averaged stratified scalar. This equation takes the form of the traditional diffusion equation but replaces the constant diffusion coefficient with a positive-definite function dependent on the solution's derivative. Numerical simulations validate the accuracy of our approximations. Our investigation of the effective equation reveals that the density profile depends on a non-dimensional parameter denoted as $\gamma$ representing the flow strength. In the large $\gamma$ limit, the system is approximated by a diffusion process with an augmented diffusion coefficient of $1+\cot ^{2}\theta$ , where $\theta$ signifies the inclination angle of the channel domain. This parameter regime is where diffusion-driven flow exhibits its strongest mixing ability. Conversely, in the small $\gamma$ regime, the density field behaves like pure diffusion with distorted isopycnals. Lastly, we show that the classical thin film equation aligns with the results obtained using the proposed expansion in the small $\gamma$ regime but fails to accurately describe the dynamics of the density field for large $\gamma$ .

Numerical model of a top-blown rotary converter preheating and charge heating with an oxy-fuel burner

Background The present work is conducted in the framework of the SisAl Pilot EU project, which aims to optimize silicon production in Europe by recycling materials and using carbon-emission-friendly technology. Silicon production experiments were conducted on laboratory and pilot scales in different types of furnaces, including top-blown rotary converters (TBRC) used as chemical reactors for molten slag-metal mixtures. In addition to experimental work, process optimization also relies on numerical modelling. Methods In this study, COMSOL Multiphysics® was used for the numerical testing of a new thermal design of TBRC by simulating its preheating and charge heating owing to an external heat source provided by an oxy-fuel burner. Results and conclusions The risk of slag solidification in TBRC during the aluminothermic reduction of silica was assessed. The model predicts that, with a useful burner power of 600 kW, the empty TBRC can be preheated to 1650°C in less than 30 min. Based on this model, the optimum burner power for maintaining the TBRC charge in a liquid state was determined. The influence of the TBRC inclination angle and its rotation frequency was studied numerically.

Experimental and theoretical model study on grouting reinforcement effect of fractured rock mass

The mechanical properties of fractured rock mass have an important influence on the safety and stability of underground engineering. Grouting is a common way to reinforce fractured rock mass. The uniaxial compression tests of red sandstone specimens with different prefabricated crack inclination angles before and after grouting were carried out. Based on the load-deformation data and synchronous image acquisition, the mechanical properties, crack propagation law and failure mode of the specimens before and after grouting were studied. The results show that the peak strength and elastic modulus of the ungrouted specimen increase with the increase of the inclination angle of the prefabricated crack. Compared with the ungrouted specimen, grouting can significantly improve the peak strength and elastic modulus of the specimen. The cracks of the ungrouted specimen mainly initiate from the tip of the prefabricated crack, and the cracks of the grouting specimen mainly initiate from the upper and lower surfaces of the specimen and the far field. Based on the macroscopic and microscopic damage theory, the constitutive model of grouting rock mass is proposed. By comparing with the experimental data, the rationality of the constitutive model is verified.

Progressive development of soil arching and deformations in two- and three-dimensional trapdoor tests

In this study, two- and three-dimensional trapdoor tests were conducted using a newly developed trapdoor test device, to investigate the evolution of soil arching and fill deformation with different relative fill densities and fill heights. The test results show that the trapdoor settlements normalised by trapdoor width required for the soil arching ratios to reach minimum and ultimate values increased with fill height. In tests with dense fill, both the minimum and ultimate soil arching ratios were smaller compared to tests with loose fill at the same fill height. Two symmetrical slip surfaces developed from the trapdoor edges, with their inclination angles dependent on the dilatation angle of the sand. The proposed Gaussian distribution function with fitting parameters well matched the measured fill settlement profile. In the dense fill tests, the settlement trough’s width and volume loss induced by trapdoor settlement gradually decreased with fill elevation due to its strong shear dilation behaviour. Conversely, the loose fill exhibited weaker shear dilation behaviour, resulting in a larger settlement region. The settlement trough width and volume loss ratio, derived from the measured fill deformation, can be used to predict the fill deformation, including the surface settlement.

Insights into surrogate respiratory droplet behaviour on inclined surfaces: Implications for disease transmission

Disease transmission via fluid ejections from infected individuals presents a significant public health challenge. The ejected droplet frequently lands on substrates with varying orientations, including horizontal, vertical, and inclined. However, the behaviour of disease-causing droplets on inclined substrates remains unexplored. Recent research has demonstrated that droplet evaporation, flow, and colloidal deposition are significantly altered when surfaces are inclined. Changes in contact angle impact evaporative flux and induce flow between the top and bottom edges of the droplet. This study examines the behaviour of simulated respiratory droplets containing NaCl, mucin, and micrometer-sized particles as pathogen surrogates, focusing on substrate inclinations of 0°, 45°, and 90° on glass surfaces. As respiratory droplets evaporate, their solute concentration rises, altering both surface tension and viscosity. The study explores the coupled effects of solute concentration variations and asymmetric evaporative flux at varying relative humidity conditions and droplet volumes. The presence of salt and mucin induces Marangoni flow, potentially altering evaporation, flow patterns, and deposition dynamics. Additionally, sedimentation flow influences crystal nucleation sites and precipitation patterns. Results reveal unprecedented crystallization dynamics on inclined substrates, with notable differences in nucleation and growth based on the angle of inclination. Optical profilometry and confocal microscopy further show that surrogate bacterial particles accumulate excessively at the bottom edge of inclined droplets, suggesting an elevated risk of pathogen survival on inclined fomites. These findings highlight the critical importance of considering substrate orientation in understanding the transmission of disease through surface-bound droplets, offering insights that could inform public health strategies.

Robotized Mobile Platform for Non-Destructive Inspection of Aircraft Structures

The robotization of the non-destructive inspection of aircraft is essential for improving the accuracy and duration of performed inspections, being an integral part of inspection and data management systems within the currently developed NDT 4.0 concept. In this paper, the authors presented the design and testing of a universal mobile platform with interchangeable sensing systems for the non-destructive inspection of aircraft structures with various angles of inclination. As a result of the performed studies, a low-cost approach of automation of existing measurement devices used for inspection was proposed. The constructed prototype of the mobile platform was equipped with eddy current testing probe and successfully passed both laboratory and environmental tests, demonstrating its performance in various conditions. The presented approach confirms the effectiveness of the automation of the inspection process using climbing robots and defining the directions of possible development of automation in non-destructive testing in aviation.

Evaluation of Maize Seed Sieving Performance using Sieves with CassiniOval Shape Openings

The process of preliminary cleaning is a determining factor affecting the standard qualities of the seeds. The grain mass that undergoes primary processing contains significant amounts of impurities, the amount of which is strictly regulated by standards. Sieves with rectangular and round openings are the most widely used for separating maize seeds. In this study, the feasibility and efficiency of using sieves with openings in the Cassini oval shape were proposed and substantiated. Three factors subject to variation during the experiments were selected, each having a crucial influence on the process parameters: rotational speed (n, rpm), specific material feed (Q, kg), and angle of sieve inclination (α, deg.). A regression equation was developed, and the response surfaces of the dependencies of defining characteristics of the process of separation of maize seeds on sieves with openings in the Cassini oval shape were compiled and analyzed. The study showed that the rotational speed has a less significant influence on the mass of the undersize of sieved maize than the inclination angle and feeding rate. A maximum grain passage (2.9 kg) into the openings in the Cassini oval shape is obtained at a rotational speed of 290.35 min-1 and a grain feed rate of 3.06 kg min-1.

On the dynamics of transporting rolling cylinders

AbstractA common, yet hazardous, method of transporting cylindrical tanks used to carry compressed gas involves rolling both tanks at opposite angles of inclination to the vertical. By propelling one of the tanks while maintaining point contact between the tanks, both tanks can be moved such that their centers of mass move in a straight line. The purpose of this paper is to explore this locomotion mechanism. First, the problem of supporting an inclined cylinder in point contact with a rough surface is examined. The analysis shows that dependent on the geometry of the cylinder and the coefficient of static friction, a wide range of angles of inclination are feasible. The presence of non-integrable constraints on the motion of the rolling cylinder is explored using the concept of a holonomy. The problem of transporting two cylinders using the aforementioned mechanism is then analyzed with the help of Frobenius’ integrability criterion for constraints and numerical simulations. The results show the mechanical advantage of transporting a pair of cylinders, the range of possible angles of inclination, and the forces needed to sustain the motion.

Enhanced Efficiency of Latent Heat Energy Storage by Inclination

Latent heat storage (LHS) has emerged as a promising solution for addressing the challenges of large-scale and long-term energy storage, offering a clean and reusable system. Being in the developmental stage, and with only limited theoretical predictions being available, there is a need to enhance the efficiency of LHS systems. In this study, we use numerical simulations to study the melting process of a phase-change material (PCM) in a rectangular domain. A significant enhancement in the melt rate of the PCM is found by a simple inclination of the domain, with a 60% increase in melt rate compared to a standard square unit without inclination through enhanced heat transfer. We establish a theoretical relation for the optimal PCM melt rate, based on the inclination angle and the domain aspect ratio, outlining the optimal conditions for the PCM melt rate, which is solely dependent on the domain geometry. We further propose a heat-transfer model that predicts the optimal aspect ratio for achieving the maximum melt rate as a function of the Rayleigh and Prandtl numbers. Published by the American Physical Society 2024

Maternal Parity Effect on Spine Posture Changes and Back Pain During Pregnancy

Background: Pregnancy can significantly alter posture and stability, thereby affecting spine curvatures. A positive relationship between the number of full-term pregnancies and the prevalence of low back pain (LBP) has been reported previously. This study aimed to analyze the impact of pregnancy on spine posture and LBP. Methods: Thirty pregnant females who were nulliparous (Group 1, n = 15) or had one or two pregnancies (Group 2, n = 15) were examined using the photogrammetric method in the first, second, and third trimesters of pregnancy. Further, a correlation analysis was conducted among the body mass index (BMI), pain intensity (VAS scale), and spine posture parameters. Results: The parous groups did not differ significantly in the parameters of the spinal posture. The thoracic angle decreased in trimester II compared to trimester I (157.77° vs. 160.55°, p = 0.004), which, according to the measurement methodology used, means that the thoracic kyphosis curvature increased. BMI was associated with the angle of trunk inclination in trimester I in Group 1 (r = 0.54, p = 0.04), as well as with the thoracic angle in trimesters II and III in Group 2 (r = 0.54–0.62, p < 0.05). A statistically significant correlation between pain intensity and spine posture parameters was more frequently observed in Group 2. Conclusions: Parity does not affect spine posture during pregnancy or pain intensity. The intensity of LBP was associated with spine posture changes during pregnancy, but the character of association differs between groups of parity. Alterations in spine posture should be monitored during pregnancy to prevent back pain.

REsolved ALMA and SMA Observations of Nearby Stars. REASONS: A population of 74 resolved planetesimal belts at millimetre wavelengths

Planetesimal belts are ubiquitous around nearby stars, and their spatial properties hold crucial information for planetesimal and planet formation models. We present resolved dust observations of 74 planetary systems as part of the REsolved ALMA and SMA Observations of Nearby Stars (REASONS) survey and archival reanalysis. We uniformly modelled interferometric visibilities for the entire sample to obtain the basic spatial properties of each belt, and combined these with constraints from multi-wavelength photometry. We report key findings from a first exploration of this legacy dataset: (1) Belt dust masses are depleted over time in a radially dependent way, with dust being depleted faster in smaller belts, as predicted by collisional evolution. (2) Most belts are broad discs rather than narrow rings, with much broader fractional widths than rings in protoplanetary discs. We link broad belts to either unresolved substructure or broad planetesimal discs produced if protoplanetary rings migrate. (3) The vertical aspect ratios ($h=H/R$) of 24 belts indicate orbital inclinations of sim 1-20$^ circ $, implying relative particle velocities of sim 0.1-4 km/s, and no clear evolution of heights with system age. This could be explained by early stirring within the belt by large bodies (with sizes of at least sim 140 km to the size of the Moon), by inheritance of inclinations from the protoplanetary disc stage, or by a diversity in evolutionary pathways and gravitational stirring mechanisms. We release the REASONS legacy multidimensional sample of millimetre-resolved belts to the community as a valuable tool for follow-up multi-wavelength observations and population modelling studies.