Formula For Height Research Articles

Utilizing ultrasonography to determine the minimal transverse diameter of the subglottic airway for informed selection of reinforced cuffed endotracheal tube models in children.

We explored the use of ultrasonography in determining the minimal transverse diameter of the subglottic airway (MTDSA) for the purpose of choosing an appropriate model of reinforced cuffed endotracheal tube. A total of 110 pediatric patients who received general anesthesia and tracheal intubation for selective surgeries at the hospital from February 2019 to February 2022 were chosen. They were then randomly assigned to three groups: 39 in the MTDSA group, 35 in the age formula group, and 36 in the height formula group. We assessed how accurately the appropriate endotracheal tube model was predicted in each group and compared their predictive performance. The age range of the enrolled pediatric patients was 3-6 years old. The ultrasonic measurement method demonstrated a prediction accuracy of 87.18%, while the age formula method and height formula method exhibited lower accuracy rates of 54.29% and 47.22%, respectively. Notably, the ultrasonic measurement method outperformed the other two methods significantly (P < 0.05). In the MTDSA group, 2 patients had their catheters changed during anesthesia, and the proportion of patients who changed their catheters was 5.13%. In the MTDSA group, 6 catheters were replaced, and the frequency of catheter replacement was 15.38%. In contrast, these percentages were much higher in the age formula group, at 31.43% and 45.71%, and in the height formula group, at 36.11% and 52.78%. The latter two groups had significantly higher values than the MTDSA group (P < 0.05). Regarding complications such as hoarseness, laryngeal edema, aspiration, and laryngospasm, the MTDSA group experienced a notably lower total incidence of 7.69% compared to the 37.14% in the age formula group and 41.67% in the height formula group, demonstrating statistical significance (P < 0.05). The ultrasonic measurement technique employed in MTDSA exhibits impressive precision when it comes to forecasting the specific model of a reinforced cuffed endotracheal tube for pediatric patients. This enhanced accuracy contributes significantly to minimizing the need for tube replacements during anesthesia and the associated complications. It holds immense importance in assisting clinicians in selecting the most appropriate pediatric endotracheal tube model for anesthesia induction.

Study on the mechanism of soil erosion by submerged water jet vertical scouring in cohesive soils

The water jet trenching technique is widely used in the burial of submarine pipelines. However, its application in cohesive soils often leads to complexity in trench morphology and challenges in predicting trench dimensions due to unclear soil erosion mechanisms. These issues significantly impact pipeline burials. To investigate the soil erosion mechanism of water jet trenching in cohesive soils, two-dimensional physical simulation experiments of submerged vertical water jet erosion were conducted. The influence of jet pressure, impingement height, and nozzle diameter on the shape of the scour hole was analyzed. The erosion damage patterns of water jets on cohesive soils were studied, and a theoretical model for the development of scour holes was established. The study revealed that when the jet velocity reaches 1000 m/s and the nozzle diameter reaches 1 mm, a contracted neck forms at the upper part of the scour hole. The appearance of the contracted neck is due to excessive jet impact energy causing impact shear failure in the soil. The effective height and width of the contracted neck increase with jet pressure and nozzle diameter and decrease with impingement height. Based on Prandtl's bearing capacity model, a model for predicting impact shear failure in cohesive soils was established, and a predictive formula for the effective height and diameter of the neck was proposed. Experimental validation confirmed the accuracy of the predictive formula. These findings provide theoretical support for the application of water jet trenching techniques in cohesive seabed soils.

New formula of vegetation roughness height and Darcy–Weisbach friction factor in channel flow

Assessing the flow resistance caused by vegetation in rivers is a hot topic in the field of hydraulics and eco-hydrology. Based on mathematical experiments by first-order closure models, new roughness height of vegetation is proposed linked with the three factors that vegetation arrangement concentration, submergence ratio, and the ratio of width to height of vegetation. Besides, new Darcy–Weisbach friction factor is built for vegetated flow. Moreover, both collected and present experimental data are adopted for verification of the roughness height and friction factor. Compared with models from other research groups, results show that the new formulas proposed in this study have high accuracy for predicting vegetation resistance in ecological restoration and water resources management in rivers.

An innovative booster-assisted dynamically installed fish anchor and its installation characteristics considering the action of ocean currents

The fish anchor is an economically viable offshore foundation engineering technology that has been proposed in recent years. By fish anchor, we mean a fish-shaped dynamically installed anchor that can penetrate into the seabed through water by its own weight. However, the existing research studies seldom consider the hydrodynamic characteristics of its free fall installation, resulting in uncertainties regarding its underwater installation characteristics. Therefore, based on OpenFOAM, this study first investigated the directional stability of fish anchors during its underwater falling process through the static model analysis method and dynamic model analysis method. The findings indicated that the directional stability of fish anchors was insufficient, rendering them suitable only for release and installation at low heights (i.e., less than 4.2 times the anchor length) without marine environmental loads. Furthermore, the anchor inclination angle during installation is significant, thereby impacting its penetration depth and pull-out capacity in the seabed. To solve this problem, the concept of an innovative booster-assisted fish anchor is proposed, which can significantly enhance the directional stability of conventional fish anchors. Results show that the maximum installation height of the new booster-assisted fish anchor is increased by 2.4 times compared to the original design, thereby enhancing both the penetration speed and uplift capacity. Based on the findings, recommended installation and construction conditions are provided. Finally, a predictive formula for the installation height and verticality of the new booster-assisted fish anchor under current action is presented to offer guidance for engineering applications.

Systematics of fusion of light nuclei

We have constructed the empirical formula for fusion barrier height (VB), fusion barrier position (RB), and inverted parabola (ħω) of light nuclei with atomic number in the range 2≤ZC≤10. This formula is obtained by studying the fusion barrier characteristics of 333 projectile target combinations. The values produced by the present formula are also compared with experiments. The present semi-empirical formula produces fusion barrier characteristics of light nuclei with the simple inputs of mass number (A) and atomic number (Z) of projectile targets. This semi-empirical formula can be utilized to calculate and interpret fusion barrier characteristics in light nuclear systems.

Influence of Deck Butt Weld Seams on Fatigue Life of Steel Bridge Decks Pavement: Parameter Optimization

Abstract The butt weld at the connection between orthotropic steel bridge decks (OSBDs) can potentially pose a hazard to the fatigue endurance of the steel bridge deck pavement. This study aims to optimize the parameters of the butt weld seam using finite element (FE) analysis. The optimized parameters will provide valuable guidance for the design of pavements with a focus on antifatigue properties. Initially, the dynamic modulus of the epoxy asphalt mixture (EAM) was determined through laboratory experimentation at various frequencies and temperatures. These material parameters were then used to compute the pavement’s fatigue life. Additionally, a well-established FE model was employed to analyze the deformation and fatigue life of the pavement structure. The validity of the model was verified by the theoretical calculation results. Various factors were considered, including vehicle velocities, pavement temperatures, and weld seam misalignments as well as weld seam dimensions such as height and width. The analysis was conducted using a three-dimensional steel bridge model. The results showed that decreasing pavement temperature, weld seam height, and misalignment led to an increase in pavement fatigue life. Conversely, reducing the weld seam width resulted in a decrease in fatigue life. Furthermore, the study investigated the coupling effect of different weld seam heights and widths on the fatigue life of the pavement. Contour figures were used to establish the parameter relationship formula for weld seam height and width. These findings are significant for pavement and deck designers because they enhance the understanding of the sensitivity of weld seams as design variables affecting the fatigue characteristics of pavement structures. Moreover, special attention should be given to the impact of welding parameters on the fatigue design of steel bridge deck pavement under high-temperature conditions of pavement structures.

Cooling Tower Plume and Drift Concentration in presence of Urban Canyon

This paper presents a computational analysis of the cooling tower plume and drift emitted by mechanical draught cooling towers situated in urban areas. The data from the Wang X (2019) and Briggs plume lift height formula are used to prove results obtained from computational Modeling of cooling tower drift and it was found to be effective. The simulation setup uses a multiphase mixture model for plume analysis and DPM for analysis of drift in the Ansys fluent. The CFD simulation results are accurate within 50 to 100 m with the Briggs plume lift height formula. The effect of wind coming from urban canyons on the cooling tower results in decreased plume lift height and increase drift concentration and deposition rate on the ground.

Self-buckling with initial imperfections: Application to trees

In most structural systems, initial imperfections, such as initial deflection, is an unavoidable challenge, and it significantly influences buckling. This study aimed to theoretically explain the effect of initial deflection and initial slope on self-buckling characteristics of heavy columns subjected to self-weight. Specifically, we examined cantilevers composed of isotropic material with a constant cross-section. Accounting for both self-weight and axial compression load, we developed a formula characterizing the self-buckling problem for some simplified cases such as sin-curve, hypergeometric curve, and straight line (initial slope). Consequently, we established the relationship between the self-buckling characteristics and the level of initial imperfections. We discovered that the greatest height for self-weight buckling is proportional to the 2/3 power of radius, regardless of the initial imperfection. Moreover, our findings suggest the potential to predict the height of tree-like natural structures using the greatest height formula and considering initial imperfections.

Plant strategies for greatest height: tapering or hollowing

The tapered form and hollow cross-section of the stem and trunk of wild plants are rational mechanical approaches because they facilitate the plant simultaneously growing taller for photosynthesis and supporting its own weight. The purpose of this study is to clarify the advantages and disadvantages of tapering and hollowing from the perspective of the greatest probable height before self-buckling. We modelled woody plants using tapering or hollow cantilevers, formulated the greatest height before self-buckling, and derived a theoretical formula for the greatest probable height considering tapering and hollowing. This formula theoretically explains why almost all plants exhibit a tapered form: it allows for a greater height at an earlier growth stage than a hollow cross-section.

Longitudinal-Torsional Ultrasonic Grinding of GCr15: Development of Longitudinal-Torsional Ultrasonic System and Prediction of Surface Topography.

The common material of bearing rings is GCr15 bearing steel which is a typical difficult-to-machine material. As an important working surface of the bearing, the inner surface of the raceway plays a vital role in the performance of the bearing. As an important means to solve the high-performance manufacturing of difficult-to-machine materials, longitudinal-torsional ultrasonic processing is widely used in various types of processing. In the presented work, the basic size of the horn is obtained from the wave equation of the forced vibration, and the modal analysis and amplitude test are carried out to verify the rationality of the LUTG structure. Then, according to the probability density function of cutting thickness and the overlapping effect of adjacent abrasive trajectories, the LUTG surface topography prediction model is established by using the height formula of the surface residual material, and the model reliability is verified by using the orthogonal test. The error between the test results and the prediction model is within 13.2%. Finally, based on the response surface method, the optimal process parameters that can meet the requirements of low roughness (Ra) and high material removal rate (MRR) are screened, and the optimal combination of process parameters is obtained as follows: A = 4.5 μm, n = 6493.3 r/min, ap = 28.4 μm, and vf = 21.1 mm/min.

THREE-COMPONENT LENS ZOOM-AFOCAL TRANSFOCAL SYSTEMS FOR THREAD RANGEFINDER

Problems. Synthesis of zoom zooms, which use zoom-afocal systems together with fixed lenses. Creation of a method of parametric synthesis of a three-component zoom-afocal system of a zoom-zoom based on the requirements for the required range of change in angular magnification, permissible cutting of peripheral beams of rays, the field of view of the system and the external location of the aperture diaphragm.&#x0D; The aim of the study. Development of a method for the synthesis of a three-component zoom-afocal system suitable for computer automation.&#x0D; Methodology of implementation. The theory of optical systems composed of thin components is used. Based on this theory, a system of equations is created in which the distances between the components are unknown. To ensure manufacturability, the first and third components of the system are identical. Using the formulas for angles and heights of zero rays, taking into account the requirements for permissible vignetting of beams and the angles of the zoom field of view, the necessary light diameters of the components are calculated.&#x0D; Research results. The resulting formulas for the overall calculation of the zoom-afocal system allow you to take into account the requirements for the longitudinal and transverse dimensions of the system, the position of the aperture diaphragm, determine the focal lengths of the components and their relative location depending on the angular magnification over the entire range of its change. It is established that a three-component system with identical first and second components has a variable axial length, which is maximal at an angular increase of one.&#x0D; Conclusions. The created method of parametric synthesis of a three-component zoom-afocal system for a zoom-zoom, in which the aperture diaphragm of a fixed lens serves as the aperture diaphragm, allows you to automate the dimensional calculation of the system and determine the laws of linear movement of its components along the optical axis.

Experimental investigation on the hazard of geyser created by an entrapped air release in baffle-drop shafts

The geyser phenomenon seriously threatens the safe operation of deep tunnel drainage systems and drop shaft structural safety. To simulate the geyser process in a baffle-drop shaft, a 1:50 scale model test system was used to research the response relationship between the geyser mechanism and test parameters such as water depth, inlet pressure, and inlet volume. The results show that the pressure in a baffle-drop shaft fluctuates sharply during the geyser process. This is caused by the release of a high-pressure air mass, and high-speed movement of the air–water mixture causes a local pressure imbalance in the drop shaft. A prediction formula for the maximum geyser height of a baffle-drop shaft was established by a multiple linear regression model. Geyser occurrence conditions for the baffle-drop shaft were proposed combined with the response relationship between different influence variables and geyser intensity. Except for the inlet pressure, submerged state of the baffles, and measured location, the hydrodynamic load on the bottom of the baffles is also related to the randomness of the air–water mixture jetted on the baffle bottom. The maximum hydrodynamic load on the baffle bottom during the geyser is 10 times the hydrodynamic load on the baffle surface under normal discharge conditions. This research provides a theoretical reference for the structural design and safe operation of baffle-drop shafts.

Development of novel parametric wave model for irregular wave height transformation

Wave height transformation is one of the most crucial parameters in studying coastal engineering as well as designing coastal structures. In this study, a wave energy dissipation model for predicting the transformation of root-mean-square wave height is proposed by using a parametric wave approach over enormous measured data. Additionally, 12 existing energy dissipation models are selected in order to verify their reliability in wave height prediction and compared with a novel formula in terms of error indices, standard deviation, capacity prediction, and root-mean-square relative error. Compiled experimental data with 5783 data are collected for examination and development. The results present that the root-mean-square relative error of existing formulas is in a range from 6.4% to 10.9%. The best existing formulas predict wave height pretty well with a root-mean-square relative error of 6.4% and a standard deviation of 11.0%. Regarding the new model, the best novel model which uses breaking wave height formula of Miche (1944) displays a lower value of root-mean-square error (6.1%) and standard deviation (8.8%) in comparison with the best existing formulas. To confirm the superior performance of the proposed model, all existing models and the best developed model are verified and compared with additional data. The accuracy of the proposed formula over verified data is still better than all existing formulas. Therefore, the novel model is strongly recommended for estimating the transformation of root-mean-square wave height.

A new connectivity model for unmanned aerial vehicle communications and flying height optimization

AbstractThis paper presents a new connectivity model for unmanned aerial vehicle (UAV) communications. We present closed‐form formulas for the probability of line‐of‐sight as a function of UAV height and distance to a ground based receiver, based on a two‐dimensional model of building and UAV locations. We show that our formulas exactly match Monte‐Carlo simulated values, whereas the existing approach over‐predicts by a factor of 2 to 3. We use the model to optimize the flying height for a UAV deployed as a mobile base station, where the goal is to maximize the number of possible connected users. We observe that the optimal height has a log‐linear characteristic. We use this to present a closed‐form formula for optimal height. We show that our techniques predict the height within 4% of realistic Monte‐Carlo simulations, and significantly outperform existing approaches which are shown to over‐predict by 40%–50%.

Applications of Airway Ultrasound for Endotracheal Intubation in Pediatric Patients: A Systematic Review

Endotracheal intubation is a challenging procedure for pediatric patients. Airway ultrasound as a new technology is suitable for aiding this process, but its diagnostic value remains unclear. We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and the Chinese biomedical literature database to summarize specific applications of airway ultrasound in each step of endotracheal intubation in pediatric patients. Diagnostic accuracy and 95% confidence interval were used as outcomes. In total, 33 studies (6 randomized controlled trials and 27 diagnostic studies) with 1934 airway ultrasound examinations were included. Population included neonates, infants, and older children. Airway ultrasound could be used to determine the endotracheal tube size and confirm endotracheal intubation and intubation depth; the diagnostic accuracy for all these factors was 23.3-100%, 90.6-100%, and 66.7-100%, respectively. Furthermore, the accuracy of airway ultrasound in predicting endotracheal tube size was consistently higher than traditional methods, such as height formula, age formula, and the width of the little finger. In conclusion, airway ultrasound has unique advantages for confirming successful endotracheal intubation in pediatric patients, and it may become an effective auxiliary tool in this field. There is a need to develop a unified airway ultrasound protocol to conduct clinical trials and practice in the future.

Rebar corrosion detection in concrete based on capacitance principle

Rebar corrosion is one of the main reasons for the deterioration of RC structures and is of major concern in the construction industry. The detection of rebar corrosion in RC is essential for maintaining building safety and improving structural durability. In this study, rebar corrosion detection based on the capacitance principle was applied and analyzed using numerical simulations and acceleration tests. The critical corrosion point and rust-layer height can be detected using capacitive sensors. Capacitive sensors with different electrode placement positions exhibit several advantages and disadvantages. The electrodes of the capacitance sensor placed in the up and down positions more easily detected rebar corrosion, and the electrodes placed on the left and right sides exhibited higher sensitivity. A formula for the rebar rust-layer height and the relationship between the capacitance and corrosion thickness were established for non-uniform corrosion. Capacitance values were used to evaluate the compactness of the RC samples.

Mechanical instability of heavy column with rotational spring

Abstract In previous research on the mechanical instability of trees based on mechanical theory, wild tree has been modeled as a cantilever which was perfectly attached to the ground. However, experimental research has identified two failure modes, including root turnover and self-buckling of the trunk. This suggests that the imperfect fixation caused by root-soil interaction must be considered when discussing tree stability. The purpose of this study is to clarify the self-buckling characteristics of wild trees considering soil instability. To account for the resistance moment caused by the interaction between the root and soil, trees as cantilevers fixed to the ground by a rotational spring were modeled. In this model, the self-buckling problem was formulated considering the rotational rigidity of the spring, and the formula derived for the critical height and buckling mode. As a result, the formula for critical height considering rotational rigidity was obtained, and it was found that the buckling modes can be classified into the rigid-body mode and beam mode based on the rotational rigidity. By comparing this result with the statistical law based on the measurement of real trees reported in previous research, it was determined that real trees were designed based on beam mode. This suggests that the wild tree skillfully balances the moment of resistance caused by the interaction between the root and soil to prevent “uprooting,” which is extremely fatal for trees. Moreover, it was also found that the safety factor of trees for self-buckling is ensured enough to prevent the beam mode.

Experimental and Theoretical Analysis of the Smoke Layer Height in the Engine Room under the Forced Air Condition

The smoke layer height in the ship engine room under forced ventilation has been experimental and theoretical investigated in this work. A series of test were carried out in a scaled engine cabin experimental platform to obtain the influence of air supply volume and air inlet height on the burning parameters, including the mass loss rate, smoke temperature, etc. The research results show that under the experimental conditions, the fire source mass loss rate increases exponentially, and smoke layer height also increases gradually with the increase in the air supply volume. The empirical formula of smoke layer height under different air supply conditions was given. Then, a prediction model of smoke layer height under different forced ventilation conditions was constructed through theoretical analysis based on conservation equations. Within the range of experimental air volume and air inlet height, the relative error between theoretical prediction results and experimental results was less than 11%, which could effectively predict the smoke layer height in the ship cabin fire.

Vertical Nonlinear Damping Experiments and Identification of High Temperature Superconducting Levitation Above Permanent Magnet Track

High temperature superconducting (HTS) magnetic levitation (maglev) train has the potential to become the next generation of high-speed rail transport due to its passive stabilization and virtually no magnetic resistance. From the maglev dynamics views, the damping between the levitated superconductor and the permanent magnet will play an important role to the further vehicle bogie design. The early experiments on HTS maglev damping illustrates that the data was very small in the no-load conditions and lacks the significant exploration of the practical-employed three-seed YBCO bulk as the levitator material. In addition, the empirical expression of the damping coefficient and the working height is still unsolved for applications. Focusing on the vertical damping of the HTS levitator levitated above the practical Halbach magnet track, a vertical vibration damping test bench is designed to conduct experiments in free levitation. Firstly, the effects of three main working factors like load, field cooling height (FCH) and excitation strength, on the vertical damping of the HTS levitation are investigated under different experimental loads. It is interesting to find the HTS levitation shows strong damping behaviors during the practical load operations above the magnet track. Based on the experimental data and theoretical analysis, the vertical damping of the HTS Maglev engineering vehicle is derived as 2×104 Ns/m, which can be close to that of a superconducting electrodynamic levitation vehicle. Secondly, the empirical formula of damping-working height is established by combining the experimental data with the theoretical formula model. It is found that the excitation strength affects the decay of damping but has little effect on the damping magnitude. Furthermore, the phenomenon of keeping constant damping ratio at the same FCH is found even though the other conditions change. This paper show evidences that the HTS maglev system is not a weakly damped system and has a strong nonlinearity in the vertical damping. The proposed empirical formula can provide reference for the bogie design of HTS maglev train.

Assessment of the Tip Position of Central Venous Catheters Inserted Using Peres' Height Formula.

The tip of a central venous catheter (CVC) should be positioned in the proximity of the cavo-atrial junction (CAJ)where thelower third of the superior vena cava (SVC) and the upperright atrium (RA) are located to prevent life-threatening complications. This study aimed to determine the accuracy of Peres' height formula in predicting the correct insertion depth of CVC. Methods:A total of 332 patients were enrolled in this prospective observational study. All CVCs were inserted using Peres' formula. The 'correct' tip position of CVC was the placement of the CVC tip 1 cm above and 1 cm below the carina inCXR. Rates of correct placements for each side and site of catheter insertions, gender, and body mass index (BMI) differences were evaluated. The correct placement rate of all catheters was 74.4%. There were statistically significant correlations between the correct placement of right-sided jugular and subclavian catheters (p<0.001) and left-sided jugular and subclavian catheters (p=0.014). There was a statistically significant difference in male patients (p=0.047). Higher BMI resulted in a lower rate of correct placement with no statistically significant difference (p=0.457). Peres' formula can be easily used to determine the correct position of CVC tips with a success rate in the Turkish population. However, practitioners should be aware of the low accuracy rate ofPeres' formula in female patients (68.5%) and patients with BMI over 35 kg/m2 (62.5%).