Height Position Research Articles

Numerical simulation of the slamming effect of regular waves and freak waves on ultra heavy-lift amphibious connector

The Ultra Heavy-lift Amphibious Connector can be used for sea and land operations. When the amphibious connector opens the bow door, it will inevitably suffer from the combined action of wind, waves, currents, and other factors, resulting in the slamming of the wave on the hatch and various landing ship hull movements in the process. Due to the complexity of the actual UHAC model, in order to save computing resources, this paper selects the external load on the UAHC hatch when it is operated in water when the door is closed. The effects of crest height, draught, and focus position on UHAC slamming under the action of regular waves and freak waves were analyzed. Based on the viscous flow theory, the CFD commercial software FLUENT is used to simulate the interaction between the reduction of regular waves and floating structures. The simulation results are compared with the experimental results to verify the feasibility of the proposed method. Since the published UHAC data cannot be found in the network environment, this paper draws the UHAC based on the only data on the Internet and studies the slamming load of the wave on the UHAC on this basis.

Method for Measuring Surface Charge on Insulating Materials Based on the Vibrating Capacitor Method

The phenomenon of surface charging, known as contact electrification or tribocharging, has wide-ranging applications but also notable hazards. Precisely measuring surface charge density in insulating materials is crucial for optimizing tribocharging and mitigating adverse effects. Although the vibrating capacitor method is commonly used for this purpose, its principle, designed for conductive materials, limits direct application to insulating surfaces, leaving the relationship between measured surface potential and surface charge density unclear. To address this issue, this study simulated the process of measuring the surface potential of insulating materials using Comsol simulations. It analyzed the effects of charged area size, probe height, and probe position, and utilized the spatial distribution of potential measurement values of surface point charges to derive an integral relationship between the distribution of measured surface potential values and the distribution of surface charge density. The integral relationship of surface potential distribution under different forms of surface charge density distributions calculated from this formula largely matches the numerical simulation results. Based on this, a relationship between the distribution of surface charge density and surface potential measurement values was further derived. This relationship can be used for measuring the surface charge density of insulating materials.

Height Adjustable Wheel Chair for Differently Abled Person

The height adjustable wheel chair focuses on meeting the needs of paraplegics ‘ patients and the poor disabled persons who desire to perform certain tasks independently and privately, such as sitting on the chair, picking items from shelves, cupboard and wardrobes at the standing height of average human being. Hence, an appropriate wheelchair to meet their need has been designed using low cost and readily available materials to achieve this product. The existing wheelchair was evaluated before its modification was done in justifying the established improvement. To achieve this, the wheel chair was redesigned with a low centre of gravity to enhance stability with the introduction of sizeable hydraulic jack to aid height adjustment. By controlling hydraulic pressure, users can elevate or lower the seat to preferred heights, facilitating ease of access to various surfaces and environments. Additionally, the hydraulic system offers stability and durability, ensuring safe operation for users of different body weights and sizes Performance evaluation of the developed wheelchair was carried out to ensure standardization in meeting the needs of the intended users. On basis of ease of operation to a chosen height of 2m using pulses generated, 79 pulses/ minutes was recorded for the improved wheelchair as against the 95 pulses/minutes of the existing wheelchair. Also it takes 28 seconds and 36 seconds for the modified and existing wheelchairs to reach the set height respectively. It offers confinement for adjustment to desired height position and provides mobility while at chosen elevated position.

Balancing competing effects of tissue growth and cytoskeletal regulation during Drosophila wing disc development

How a developing organ robustly coordinates the cellular mechanics and growth to reach a final size and shape remains poorly understood. Through iterations between experiments and model simulations that include a mechanistic description of interkinetic nuclear migration, we show that the local curvature, height, and nuclear positioning of cells in the Drosophila wing imaginal disc are defined by the concurrent patterning of actomyosin contractility, cell-ECM adhesion, ECM stiffness, and interfacial membrane tension. We show that increasing cell proliferation via different growth-promoting pathways results in two distinct phenotypes. Triggering proliferation through insulin signaling increases basal curvature, but an increase in growth through Dpp signaling and Myc causes tissue flattening. These distinct phenotypic outcomes arise from differences in how each growth pathway regulates the cellular cytoskeleton, including contractility and cell-ECM adhesion. The coupled regulation of proliferation and cytoskeletal regulators is a general strategy to meet the multiple context-dependent criteria defining tissue morphogenesis.

SOME PHYSICAL AND MECHANICAL PROPERTIES OF COCONUT PALM (COCOS NUCIFERA) STEM IN HAINAN ISLAND, CHINA

The physical and mechanical properties of 40-year-old coconut stem were investigated in different radial directions and height positions. The results showed that in the radial direction, the properties of the number of vascular bundles (NVB), density, shrinkage, compressive strength parallel to the grain (CS), modulus of rupture (MOR), and modulus of elasticity (MOE) decreased continuously from the outer area to the inner area, except for the water absorption (WA) value which increased from the outer area to the inner area. The density and MOE decreased from the bottom to the top in the height direction while NVB and WA increased. The shrinkage, CS, and MOE first increased and then decreased from the bottom to the top. NVB in coconut stem affects the density and determines the main mechanical properties of CS, MOR, and MOE. The analysis of variance (two-way ANOVA) showed a significant difference in density, NVB, WA, CS, MOR, and MOE in radial direction and height position. These findings can be useful for the development of new applications for coconut stems, such as in construction, landscaping, or furniture manufacturing, as well as for improving our understanding of their structural characteristics.

An investigation into the flexural properties of sawn timber and poles of South African grown Pinus maximinoi (H.E.Moore)

Pinus maximinoi is a species that can potentially be deployed commercially to provide structural timber and poles for the South African market. The objective of this study was to investigate the flexural properties of sawn timber and poles of P. maximinoi from young plantations of the Southern Cape. A total of 60 trees and 150 logs for the sawmill study were obtained from two research trials on the Longmore estate in the Humansdorp area (13.7 years old), and on the Kruisfontein estate close to Knysna (9.0 years old). Some 74 poles from the same compartments were removed and tested in bending. The P. maximinoi sawn timber had excellent bending properties, superior to sawn timber from other South African Pinus species, tested at similar radial positions in previous studies. Analysis of variation showed that site, log height and board radial position had a significant influence on the modulus of elasticity (MOE) of sawn timber. Multiple regression analysis showed that board MOE can be predicted using a model including tree taper, time-of-flight measured with Treesonic and wood density (model R 2 = 0.87). The P. maximinoi poles complied with the mean MOE national standard requirement SANS 457-2 of 9 000 MPa but not with the fifth percentile (bending strength) modulus of rupture (MOR) requirement of 34 MPa. This study and other research, however, showed that the national standard requirement for MOR of poles might be too high for current log resources in South Africa. The investigation into the bending and other properties of P. maximinoi sawn boards and poles showed extremely positive results. Based on this wood quality study of P. maximinoi, it is certainly a very promising species for deployment in the Southern Cape and potentially other regions in South Africa.

Experimental study of symmetrical ferrofluid seals with single magnetic source and small clearance

To enhance the sealing pressure of normal ferrofluid seals with single magnetic source and small sealing clearance, a symmetrical ferrofluid seal (SFFS) was designed. The study utilizes a combination of finite element simulation and experiments to investigate the influence of crucial factors, including sealing clearance, number of pole teeth, step height, and pole teeth position, on the sealing pressure of SFFS. The findings indicate that the experimental sealing pressure values for SFFS closely match the theoretical sealing pressure values. The sealing pressure of the SFFS decreases as the sealing clearances and step height increase. It increases with an increase in the number of pole teeth.

Chemical composition and solubility properties of Bambusa bambos at different ages and height positions

Sustainable materials are becoming increasingly important due to environmental concerns and the energy crisis. Non-wood resources such as bamboo are being explored as alternatives to wood-based materials to reduce deforestation. However, the chemical properties of these resources determine their usability. This study analyzed the chemical composition and solubility of Bambusa bambos (L.) Voss, a type of bamboo. The effects of age and height position (top, middle, and bottom) on the chemical composition and solubility were also considered. The study followed the standards of TAPPI (Technical Association of the Pulp and Paper Industry) to analyze holocellulose, lignin, and extractive content, and water (hot and cold) and caustic soda (1% NaOH) solubility. The results showed that the chemical composition, i.e., holocellulose, lignin, and extractive, increased while solubility, i.e., cold water, hot water, and NaOH, decreased with the ageing of B. bambos. The average holocellulose, lignin, and extractive contents of three-year-old B. bambos were 70.49%, 27.55%, and 4.54%, respectively. These values were within the range of previous studies, indicating that B. bambos has potential applications in various purposes.

Verification of nano-particle absolute height position measurement from a surface with invisible reference tilt resin by multi-wavelength evanescent fields

Verification of nano-particle absolute height position measurement from a surface with invisible reference tilt resin by multi-wavelength evanescent fields

Mechanical properties of laminate materials based on polylactic acid and polyvinyl chloride meshes as reinforcement

The 3D printing parameters are known to have a significant impact on manufactured parts, and the layered morphology of these parts makes mechanical design analysis for engineering applications difficult. In this work, the tensile strengths and microhardness of 3D printed polylactic acid (PLA) specimens with different orientations and numbers of individual layers of mesh material (polyvinyl chloride – PVC) were investigated as a laminate composite. Composite specimens were obtained using 3D printing via fused deposition modelling (FDM). Moreover, the influence of printing parameters (i.e. infill density and layer height) and the number and orientation of reinforced meshes on the mechanical response was investigated. Fracture strength of PLA/PVC laminate composites ranges from 31.30 MPa (3 PVC mesh layers; mesh height position: 25 %│50 %│75 %; infill density: 60 %; PVC mesh orientation: 90°│45°│90°; layer height: 0.2 mm) to 18.62 MPa (without PVC mesh; infill density: 30 %; layer height: 0.1 mm) demonstrating a significant impact of the number of the PVC mesh layers, infill density of PLA and layer height on the final mechanical parameters of printing PLA/PVC elements. The surface hardness at the micro load level showed that the number of reinforcement layers affects the microhardness value, as well as material filling and mesh orientation. The specimen with the following parameters gave the best results: layer height: 0.2 mm; 3 PVC mesh layers; infill density: 60 %; PVC mesh orientation: 90°│45°│90°. The average hardness values for one layer and three layers of mesh were in accordance with tensile test results.

Calculation of the temperature condition of a thermostabilizable base with a single pile

The article deals with one of the main problems of construction in the area of permafrost soils - the presence of sites represented by thawed permafrost soils [1-3], formed due to natural conditions (waterlogged site, site relief features, swamping, etc.) and man-made impacts (warming effect of buildings and structures, systematic discharges and leaks from engineering networks, runoff and stagnation of surface rainwater, etc.). To ensure the bearing capacity of a single pile and the specified temperature regime of the foundation soils in the given engineering-geocryological conditions, it is possible to use the cooling devices of seasonal action. The main issue when using the cooling devices of seasonal action is to determine the main parameters affecting the bearing capacity of a single pile and the deformability of the foundation. To determine the parameters affecting the bearing capacity of a single pile and the deformability of the foundation, a set of numerical temperature calculations of thermostabilized soil mass represented by thawed permafrost soils with a single pile under different initial boundary conditions was performed in the certified Frost 3D software package. Temperature calculations were performed for the thawed soil mass, in which a single reinforced concrete pile with a single vertical vapor-liquid thermal stabilizer structure is submerged. The geometrical dimensions of the calculated area are 30 × 30 × 30 m. Based on the results of numerical experiments, the main physical, thermal and geometric parameters of the formed frozen core have been determined, which will be incorporated into the methodology for predicting the bearing capacity of a single pile in a thermally stabilized viscoelastic foundation represented by thawed permafrost soils. On the basis of the calculations performed, a design diagram of a single pile in a thermostabilized foundation was built and graphical dependences of changes in the diameter, height and geometric position of the frozen core depending on the initial boundary conditions were plotted.

Optimization of an Oil–Gas Separator of Gas Storage Compressor with Consideration of Velocity Uniformity in Filter Inlets

The oil–gas separator of the gas storage compressor serves as crucial equipment in a natural gas storage system to improve gas storage purity and efficiency. Its optimization is also essential to improve the separation efficiency and lifespan. Collision and centrifugal separation are two widely used optimized structures for oil–gas separators, and the enhancement in separation efficiency, as well as the decrease in pressure loss of optimized separators, has been thoroughly discussed. However, the velocity uniformity in the filter inlet has not been considered, which affects the filtration performance. Thus, the overall efficiency of the separator is reduced. Accordingly, optimization of an oil–gas separator with the consideration of velocity uniformity in filter inlets is introduced in this study. The effects of critical dimension parameters of optimized equipment on separator performance were analyzed. The results show that bb = 0.4, lb = 3, hb = 1.5, and kb = 0.5 and le = 0.9 and he = 4.11, as well as lc = 0.5 and dc = 0.52, are suitable for the case of placing baffles, adjusting the separator height and inlet position, as well as adding an inner cylinder, respectively. Subsequently, the analytic hierarchy process was employed to compare different optimized cases. It is observed that the overall rating for adding an inner cylinder reaches 88.46, which is the more suitable optimized method for the oil–gas separator. This work is relevant for oil–gas systems to improve their separation efficiency and enhance the gas storage performance.

A continuous depth encoding PET detector using side readout of dual-layer GAGG crystals with SiPM array

A continuous depth encoding positron emission tomography (PET) detector using a side readout configuration with dual-layer GAGG scintillators of different decay times, coupled to a Silicon Photomultiplier (SiPM) array is proposed. The performance of the detector was evaluated through experimentation. The detector consists of an upper layer with a 1 × 4 fast decay GAGG (GAGG-F) crystal array and a lower layer with another 1 × 4 high-light-yield GAGG (GAGG-HL) crystal array. The 2 × 4 GAGG crystal array is then coupled to the 4 × 6 SiPM array. The SiPM array's sum signal is utilized for layer identification, while 24 individual signals are used to measure the 3D position of the gamma interaction. The experimental measurements demonstrate that the detector effectively resolves all crystal units and provides continuous depth information in the Z-direction. Utilizing the time over threshold method for dual-layer identification in coincidence mode yielded an accuracy of 96.4 %, whereas the pulse decay time method achieved an accuracy of 95.7 %. The average energy resolution was found to be 12.1 % and 11.2 % for the upper and lower GAGG crystal arrays, respectively. Using the maximum value-to-sum ratio method, the upper GAGG-F crystal layer displayed clear distinction and accurate assignment at two height positions, achieving a correct assignment rate of 90.5 %. In contrast, the lower GAGG-HL crystal layer exhibited poorer resolution at each height position, with correct assignment percentages dropping to 71.1 %. Employing the center of gravity position estimation method for the GAGG-F and GAGG-HL layers, the average Z spatial resolution was determined as 3.56 ± 0.33 mm (FWHM) and 3.35 ± 0.28 mm (FWHM).

Influence of local factors on the condylar growth after arthroscopic discopexy in adolescents with temporomandibular joint anterior disc displacement without reduction: a retrospective longitudinal study

The aim of this retrospective longitudinal study was to investigate the condylar growth after arthroscopic discopexy in adolescents with temporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR), and to determine whether local or systemic factors influence this growth. A total of 145 patients aged 10–20 years who were diagnosed with ADDwoR by magnetic resonance imaging were included. Patients who underwent arthroscopic discopexy were assigned to the arthroscopy group (n = 108) and others to the control group (n = 37). Demographic information, clinical assessments, body indicators, and bone density information were collected. Condylar height, disc length, and disc position were measured. The mean condylar height change in the arthroscopy group was 2.12 mm more than that in the control group (P < 0.001). Condylar growth after surgery was negatively correlated with age (P = 0.017) and disc length (P = 0.015), and positively correlated with follow-up duration (P = 0.002) and disc position (P < 0.001). Moreover, arthroscopic discopexy patients had better outcomes regarding improvements in pain (P = 0.024), maximum inter-incisal opening (P < 0.001), and quality of life (P < 0.001) than control patients. In conclusion, arthroscopic discopexy can restore condylar growth and relieve symptoms in ADDwoR patients, and the condylar growth is closely related to the local factors.

Shelf acetabuloplasty may inhibit range of motion: A computer simulation analysis.

Shelf acetabuloplasty has been performed in patients with developmental dysplasia of the hip (DDH); however, the appropriate position of the shelf has not been determined, particularly with respect to avoiding range of motion (ROM) loss. The aim of this study was to investigate the frequency of ROM inhibition and the influence of 3D position of the shelf following actual shelf acetabuloplasty and virtual surgery using computer simulation analysis. Computed tomography data from 15 patients with DDH who underwent shelf acetabuloplasty were collected between August 2019 and February 2022. The three-dimensional models of a hip joint were constructed using Zed Hip®. Maximal internal rotation (MIR) at 45° and 90° flexion was measured in each patient. The frequency and position of ROM inhibition was determined in a real postoperative model virtually. In addition, a second analysis using virtual acetabuloplasty was performed. Upon placing the shelf, three patterns were provided for the following four parameters: height, coronal inclination, center-edge angle (CEA), and anteroposterior position. The predictors for ROM inhibition were analyzed using a logistic regression model. In the actual postoperative model, a limitation of MIR at 90° and 45° of flexion occurred in 60% and 66.7% of patients, respectively. A higher CEA and anterior position are major factors limiting MIR. The analysis of the virtual shelf acetabuloplasty model revealed that anterior position and CEA were significant factors causing ROM inhibition. As for clinical significance, the results of the current study indicated the optimal location of the shelf to avoid iatrogenic impingement after shelf acetabuloplasty.

Effect of cold storage backfill on thermal comfort of mine stope based on standard effective temperature

In order to effectively evaluate the thermal comfort during the process of mine cold storage backfill cooling, SET (standard effective temperature) was selected as the evaluation index. According to the actual situation, the physical model and heat transfer model of mine were established. The air temperature distribution was obtained by numerical simulation, and the backfill cooling experiment was carried out. The key factors affecting thermal comfort were analyzed and discussed according to the calculation results of the SET program. The results showed that air temperature has the greatest influence on mine thermal comfort among various environmental factors. Based on the average temperature of stope, the downward backfill can maintain comfort longer than the upward backfill. From the perspective of comfort at different height positions, downward backfill is better than upward backfill. Considering various factors such as cooling effect, rheological characteristics and refrigeration cost, the ratio of ice to water in backfill slurry can be set at 6:4. The research results can provide reference for the reasonable adjustment of thermal environment in mine.

The Structure of the Warped Io Plasma Torus Constrained by the Io Footprint

AbstractStandard models of force balance along Jovian field lines predict the location of the Io Plasma Torus to be the centrifugal equator of Jupiter’s magnetosphere, that is, the position along the magnetic field lines farthest away from Jupiter’s rotational axis. In many models, the centrifugal equator is assumed to lay on a plane, calculated from a (shifted) dipole magnetic field, rather than on a warped surface which incorporates Jupiter’s higher magnetic field moments. In this work, we use Hubble Space Telescope observations of the Io Main Footprint to constrain density, scale height, and lateral position of the Io Plasma Torus. Therefore, we employ the leading angle of the footprints to calculate expected travel times of Alfvén waves and carry out an inversion of the observations. For the magnetic field, we use the JRM33 magnetic field model. The inversion results show peak densities between ρ0 = 1,830 cm−3 and ρ0 = 2,032 cm−3 and scale heights between H = 0.92RJ and H = 0.97RJ consistent with current literature values. Using a warped multipole centrifugal equator instead of a planar dipole increases the quality of the fit by about 25%. We additionally develop two tests to confirm that the multipole centrifugal equator from the JRM33 model fits explains the applied data set better than the dipole centrifugal equator. The quadropole moments alter Io’s relative position to the torus, which changes the plasma density around Io by up to Δρ/ρ = 20%.

The adaptation top crosses of anthocyanins corn in lowland zone of Palu Indonesia

Anthocyanins corn held to increase of human health, the color of seeds was orange to black. The experiment was to studied characters of some families as top crosses anthocyanins corn under interaction genotypes (G), and season (S) in valley of Palu in Indonesia. The experiment was conducted by randomized complete block design with three replications in experimental farm of Sidondo under two season rainy and dry condition. There are ten top crosses populations as anthocyanins corn as candidate included check to evaluated on 2017. The objective of experiment was to study of characters and to find of which is genotypes was stable and high yield to promoting as candidate for F1 top crosses varieties. Interaction data between genotype (G) and season (S) were analyzed manually. The result show that there are significant interaction GxS and founded the genotypes would be promising as new F1 candidate was PMU(S1) Synt. F. C1-2-3xtester: PPH(S1) C2. The potential would be founded 6.0 - 7.0 t/ha, characters of candidate was scored one of plant aspect, position of ear height is middle of plant height, and there are 45 days for anthesis. The released top crosses of anthocyanin corn would be develop under poor farmers for aims to increase income, health and anticipated of mall nutrition.

Prevalence of yam nematodes in diverse soil communities, and their morphometrics in the Krachi-Nchumuru District of Ghana

Yam (Dioscorea spp.) is susceptible to dry rot disease, which limits its yields in farmers fields in West Africa.The objective of this study was to assess the occurrence and characteristics of the plant-parasitic nematode (Scutellonema bradys) on yam from the Volta Region of Ghana. A survey was conducted in KrachiI-Nchummuru District in the Volta region in Ghana, using a semi-structured questionnaire in ten communities. Majority of the farmers (62%) were unaware of nematodes and their damage caused to yam. Most interviewees (84%) mentioned the ‘pona’ yam variety as the most susceptible genotype to rot, especially in storage. Twelve nematode genera were identified in soils, and eight under storage conditions. Soil samples had, for relative abundance, 31.5% of nematodes as Scutellonema bradys and 16.8% as Meloidogyne spp. On the other hand, relative abundances in yam peels for S. bradys, Meloidogyne spp. and Pratylenchus spp. were 88.4, 6.0 and 3.3%, respectively. Body lenghts of female S. bradys ranged from 747.3 to 861.9 um. There was a strong positive correlation between tail length and head region diameter (r = 0.81); and stylet knob height and vulva position (r= 0.68). Agglomerative hierarchical clustering (AHC) showed 5 major groups at a dissimilarity of 90%, with sub-groups formed at dissimilarity value of 50%. In-depth survey of communities in the Krachi Nchumuru district revealed that, Scutellonema bradys is a threat to yam production in this region, and results in considerable dry rot disease and yield losses.

Morphologic Changes of the Intervertebral Disk During Growth.

Cross-sectional. The aim of this study was to describe morphologic changes of the annulus fibrosus (AF) and nucleus pulposus (NP) in children during growth using magnetic resonance imaging. Little is known of intervertebral disk (IVD) maturation as opposed to degeneration, such as changes in relative AF/NP proportions and orientation during growth. Studies suggest that IVD plays a role in the etiology of pediatric spinal deformities. Therefore, understanding the morphologic development of the AF and NP during growth is key. An existing database of children aged 0 to 18 that had magnetic resonance imaging for indications unrelated to the spine were analyzed. The AF/NP were segmented semiautomatically from T1 to L5. The parameters: mean IVD height, cross-sectional area, slenderness (height/width ratio), volume (ratio), and relative position of the centroid of the NP within the IVD in three directions ( x , y , z ) were extracted, and compared between age, sex, and spinal level. IVD height increased modestly and predominantly in the low-thoracic and lumbar spine during the first 5 to 10 years of life. Cross-sectional area and thus volume increased steadily at all levels throughout growth. IVD slenderness decreased sharply in the first years of life and remains relatively stable throughout the remainder of growth. IVDs were smaller and more slender in females, especially in the mid-thoracic spine at early adolescence. In the upper-thoracic and mid-thoracic spine the NP comprises 10% to 12% of total IVD volume during growth, this percentage increases in the low-thoracic and lumbar spine towards 20% to 25%. In the anterior-posterior direction, the position of the nucleus increasingly shifts with age, possibly in line with the developing sagittal profile of the spine. This study describes the development of thoracic and lumbar IVDs during growth and may be used as a reference for future studies on the role of IVD in the etiology of disk-related disorders.