High Overload Research Articles

Design and Analysis of Special-Shaped Pole Piece PMSM With Low Vibration and High Overload Capacity

Design and Analysis of Special-Shaped Pole Piece PMSM With Low Vibration and High Overload Capacity

Fuze vibration reduction design based on high-speed rocket sled vibration effect

Abstract Rocket sled is one of the important methods to realize the performance test in fields such as aerospace and weapon equipment. In response to the extremely high overload phenomenon of the tested fuze system in rocket sled impact tests, this paper proposes a new method of fuze vibration reduction. By optimizing the layout and multi-layer potting of fuze shell and internal components, the influence of vibration effects on electronic components is effectively reduced. Comparative analysis of results is based on epoxy resin sealant potting, silicone rubber potting, or without additional protection, to further improve the safety and service life of internal key components and provide necessary structural reference for vibration reduction treatment in rocket sled tests.

Research on the mechanism of electromechanical coupling response of pulse power multilayer ceramic capacitors under high impact and high voltage discharge composite environment

Pulse power multilayer ceramic capacitors (pulse power-MLCC) are commonly used in complex composite environments with high overload and high voltage due to their large size and capacitance. In order to study the electromechanical coupling response characteristics of pulse power-MLCC in high-impact and high-voltage composite environments, a split Hopkinson pressure bar (SHPB) testing system was used to simulate high impact. The mechanical and electrical parameters of pulse power-MLCC were collected under high-impact and voltage environments, and the capacitance changes at different impact velocities were obtained. The stress wave transmission characteristics of pulse power-MLCC were studied by combining numerical simulation and theoretical analysis, and the structural deformation of ceramic dielectric under impact stress was analyzed. The relationship between the capacitance and DC bias of the capacitor was analyzed. A capacitance calculation model for pulse power-MLCC in an electromechanical coupling environment was established, revealing the electromechanical coupling mechanism of pulse power-MLCC.

Multi-objective parameter matching of elastic ring for rotor system by using particle swarm optimization method

PurposeElastic rings served as the elastic supporting elements which have been extensively used in the aeroengines for maneuverable planes with high overloading. However, under extreme conditions, the elastic ring contacts the bearing seat, causing elastic ring failure. Therefore, it is necessary to optimize the matching parameters of the elastic ring in order to suppress the occurrence of elastic ring failure under harsh working conditions.Design/methodology/approachIn this paper, a rotor system supported by elastic rings is researched and a multi-objective parameter matching method of elastic ring is proposed, considering the elastic ring failure, rotor system’s frequency forbidden zone and rotor system’s dynamic response. Then, the particle swarm optimization algorithm is used to dynamically constrain the parameter matching space and obtain the ideal solution for the elastic ring parameter matching.FindingsBy analyzing the elastic ring’s matching results (different unbalanced forces and disk masses), the relationship between the trend of Pareto front changes and rotor system parameters is studied. In addition, the rotor system’s dynamic characteristics before and after parameter matching are analyzed.Originality/valueThis article provides guidance for the design of elastic rings by matching the parameters of elastic rings.

The Mediating Effect of Social Participation Restriction on the Association Between Role Overload and Mental Health Among Caregivers of Older Adults with Dementia.

Caregivers of older adults with dementia (dementia caregivers) often experience high role overload (i.e., feeling overwhelmed by caregiving demands that exceed available resources), which can take a toll on their mental health. Moreover, dementia caregiving can restrict caregivers' participation in valued social activities. This study aims to examine the mediating effect of social participation restriction on the relationship between role overload and mental health among dementia caregivers. A total of 894 dementia caregivers (mean age = 61.77) were selected from the National Study of Caregiving. The sample was predominantly women (64%) and White (78%). Path analysis shows that social participation restriction partially mediated the associations between (1) role overload and psychological distress (indirect effect β = .08, p < .001) and (2) role overload and psychological wellbeing (indirect effect β = -.05, p < .05). Interventions targeting coping strategies and healthcare-recreation programs are needed to improve social participation among dementia caregivers.

Experiment and Optimization of Stepwise Graded Foam for Enhanced High Overload Shedding Property

Experiment and Optimization of Stepwise Graded Foam for Enhanced High Overload Shedding Property

Simulation and optimization of fuze circuit housing structural strength under a high overload environment

Abstract With the continuous improvement of modern military equipment protection systems, the demand for ammunition to penetrate hard targets has become increasingly apparent. The projectile is subjected to a high overload environment during launching and penetrating hard targets. Fuze as the detonation control system of the projectile, is prone to significant deformation or even damage to its circuit housing structure in a high overload environment. The dynamic response of fuze circuit housing under high overload conditions is analyzed, and the housing structure is further optimized according to the simulation results to ensure that the fuze circuit housing can meet the strength requirements under a high overload environment.

Model simulation analysis of superconducting switch applied to high-temperature superconducting electromagnetic suspension magnet

This paper presents a simulation analysis of the switching characteristics of a thermal control superconducting switch used in high overload electromagnetic suspension trains. A two-dimensional axisymmetric model was established using superconducting tape encapsulated in non-copper-plated stainless steel. Simulation analysis of thermal control switch heating and quenching was performed in the absence of an external magnetic field. The simulation results show that the switching resistance is 4.

Circular SAW Resonators: Influence of Sensitive Element Dimensions on Strength Characteristics and First Experimental Samples.

In preceding research endeavors, the frequency characteristics of a ring resonator on surface acoustic waves made of various materials were studied. Investigations encompassed fixation techniques within the housing, the impact of external variables on these components, and the most efficient configuration of the interdigital transducer within the ring resonator to curtail bandwidth. This current study is dedicated to investigating the correlation between sensitivity and the highest measurable acceleration concerning the dimensions of these sensitive elements. Furthermore, it involves assessing the attributes of produced experimental samples to verify the simulation results. The results obtained represent the possibility of creating a micromechanical accelerometer that can be used in the automotive industry as a g-sensor shock, as well as in industries where the numerical value of high overloads is required.

Piezoelectric Micromachined Microphone with High Acoustic Overload Point and with Electrically Controlled Sensitivity.

Currently, the most advanced micromachined microphones on the market are based on a capacitive coupling principle. Capacitive micro-electromechanical-system-based (MEMS) microphones resemble their millimetric counterparts, both in function and in performance. The most advanced MEMS microphones reached a competitive level compared to commonly used measuring microphones in most of the key performance parameters except the acoustic overload point (AOP). In an effort to find a solution for the measurement of high-level acoustic fields, microphones with the piezoelectric coupling principle have been proposed. These novel microphones exploit the piezoelectric effect of a thin layer of aluminum nitride, which is incorporated in their diaphragm structure. In these microphones fabricated with micromachining technology, no fixed electrode is necessary, in contrast to capacitive microphones. This specificity significantly simplifies both the design and the fabrication and opens the door for the improvement of the acoustic overload point, as well as harsh environmental applications. Several variations of piezoelectric structures together with an idea leading to electrically controlled sensitivity of MEMS piezoelectric microphones are discussed in this paper.

Electro-thermal co-design of a variable pole toroidal induction motor

The United States Department of Energy targets an 88 % reduction in motor and power electronics volume by the year 2025 while minimizing or eliminating magnet usage. Induction machines are a magnet-free alternative with advantages such as low cost, high reliability, and capability of withstanding high short-term overload. To meet these societal goals, we develop an induction machine that uses an electro-thermal co-designed converter-integrated thermal management approach. The machine utilizes toroidal windings in the stator, and an 18-phase power converter to achieve 40 kW/L power density. An optimized jacket design was developed to enable the effective thermal management of the stator and integrated power electronics. The toroidal winding configuration provides advantages for thermal performance over conventional distributed windings due to an increased winding copper surface area without reducing slot-fill factor, thereby allowing for a higher stator density. The improved thermal performance of the toroidal winding design was verified using three-dimensional conjugate computational fluid dynamic simulations. A reduced-order transient model was then developed to generate torque-speed-temperature plots at various load conditions. The transient thermal analysis was extended to verify safe operation of the motor during a typical drive cycle for the desired application. The thermal design models developed in this work are robust and scalable to other motor sizes providing a framework for co-designing and developing thermal management systems for electric motors.

Enterocyte-specific FATP4 deficiency elevates blood lipids via a shift from polar to neutral lipids in distal intestine.

Fatty acid transport protein (FATP)4 was thought to mediate intestinal lipid absorption, which was disputed by a study using keratinocyte-Fatp4-rescued Fatp4-/- mice. These knockouts when fed with a Western diet showed elevated intestinal triglyceride (TG) and fatty acid levels. To investigate a possible role of FATP4 on intestinal lipid processing, ent-Fatp4 (KO) mice were generated by Villin-Cre-specific inactivation of the Fatp4 gene. We aimed to measure circulating and intestinal lipids in control and KO mice after acute or chronic fat intake or during aging. Remarkably, ent-Fatp4 mice displayed an approximately 30% decrease in ileal behenic, lignoceric, and nervonic acids, ceramides containing these FA, as well as, ileal sphingomyelin, phosphatidylcholine, and phosphatidylinositol levels. Such decreases were concomitant with an increase in jejunal cholesterol ester. After a 2-wk recovery from high lipid overload by tyloxapol and oral-lipid treatment, ent-Fatp4 mice showed an increase in plasma TG and chylomicrons. Upon overnight fasting followed by an oral fat meal, ent-Fatp4 mice showed an increase in plasma TG-rich lipoproteins and the particle number of chylomicrons and very low-density lipoproteins. During aging or after feeding with a high-fat high-cholesterol (HFHC) diet, ent-Fatp4 mice showed an increase in plasma TG, fatty acids, glycerol, and lipoproteins as well as intestinal lipids. HFHC-fed KO mice displayed an increase in body weight, the number of lipid droplets with larger sizes in the ileum, concomitant with a decrease in ileal ceramides and phosphatidylcholine. Thus, enterocyte FATP4 deficiency led to a metabolic shift from polar to neutral lipids in distal intestine rendering an increase in plasma lipids and lipoproteins.NEW & NOTEWORTHY Enterocyte-specific Fatp4 deficiency in mice increased intestinal lipid absorption with elevation of blood lipids during fasting and aging, as well as after an acute oral fat-loading or chronic HFHC feeding. Lipidomics revealed that knockout mice displayed a shift from very long-chain to long-chain fatty acids, and from polar to neutral lipids, predominantly in the ileum. Thus, FATP4 may have a physiological function in the control of blood lipids via metabolic shifts in distal intestine.

Analysis of the mechanical response of solid rocket engine propellant under acceleration shock

The increased-range solid rocket engine of new ammunition often needs to withstand extremely high acceleration overload, leading to damage to the propellant’s structural integrity. To address this issue, this paper constructs a nonlinear viscoelastic constitutive model for the CMDB propellant by using low- and high-strain rate mechanical property tests. Combined with the secondary development of explicit dynamics and numerical simulation technology, the mechanical response of a certain type of solid rocket propellant under different acceleration impacts is analyzed. The results show that under acceleration impact loads, the propellant will compress, rebound, and recover over time, continuously cycling. Its axial displacement, maximum equivalent stress, and maximum equivalent strain exhibit irregular sinusoidal wave-like periodic cycles. Looking at the time when the peaks appear, the time when the maximum equivalent stress appears always lags behind the time when the maximum axial displacement peak appears. Due to the viscous effect of the viscoelastic material of the propellant, the time when the equivalent strain peak appears will lag behind the equivalent stress. Because of the material’s damping effect, both the peak values of the maximum equivalent stress and equivalent strain decrease over time. Under continuous high acceleration impact loads, this viscous damping phenomenon continuously diminishes, and the peak value of the propellant’s axial displacement gradually increases.

A modified local thermal non-equilibrium model of transient phase-change transpiration cooling for hypersonic thermal protection

Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale, a new two-phase mixture model is developed by incorporating the local thermal non-equilibrium effect. Considering the low-pressure and high overload working conditions of hypersonic flying, the heat and mass transfer induced by capillary and inertial body forces are analyzed for sub-cooled, saturated and super-heated states of water coolant under varying saturation pressures. After the validation of the model, transient simulations for different external factors, including spatially-varied heat flux, coolant mass flux, time-dependent external pressure and aircraft acceleration are conducted. The results show that the vapor blockage patterns at the outlet are highly dependent on the injection mass flux value and the external pressure, and the reduced saturation temperature at low external pressure leads to early boiling off and vapor blockage. The motion of flying has a large influence on the cooling effect, as the inertial force could change the flow pattern of the fluid inside significantly. The comparison of the results from 2-D and 3-D simulations suggests that 3-D simulation shall be conducted for practical application of transpiration cooling, as the thermal protection efficiency may be overestimated by the 2-D results due to the assumption of an infinite width length of the porous plate.

Correlation between school material transportation and postural changes in elementary school students

Postural problems in young people begin during the growth phase and may be correlated with the transport of school materials, since the excessive weight of backpacks generates mechanical overload on the body, leading young people to a high effort overload, triggering muscle imbalance and pain. In this context, the present study aimed to verify the correlation between transporting school materials and postural changes in young people in elementary school. This is a cross-sectional analytical study. The sample selection included 13 elementary school students, aged between 10 and 12 years old. These students had total body mass and height measured, answered an anamnesis, underwent a postural assessment and, finally, were asked about transporting school supplies, including identifying the weight of the backpack they were carrying. The data was subjected to a descriptive statistical analysis, including calculations of mean, standard deviation and percentages to characterize the variables. Furthermore, the Pearson test was performed to evaluate the correlation between postural changes and the transport of school materials. The results revealed that 76.92% of students reported back pain, as well as changes in posture. Additionally, 69.23% do not practice physical exercise, and 84.62% said they felt tired when carrying school supplies. Factors such as age, gender, height, BMI and physical activity can influence the onset of back pain. This can be justified by the correlation between weight and BMI (r=0.933; p=0.001), sex and height (r=-0.607; p=0.036), weight and sex (r=-0.576; p=0.049), and weight and height (r=0.698; p=0.012). Therefore, we conclude that physical inactivity and inadequate transport of school material can contribute to changes in posture, with these factors being influenced by the age group, weight and height of the individuals.

A MEMS Disk Gyroscope with High Fabrication Precision, High Quality Factor (>810k) and High Overload Characteristic (>15000g)

This paper presents an electromagnetic MEMS disk gyroscope based on fused silica to enhance the accuracy of MEMS gyros under high overload conditions. A laser-induced modified wet etching (LIE) technology was utilized for gyro fabrication and a detailed analysis was conducted on the factors affecting quality factor (Q-value) of the gyro. The LIE process parameters were optimized using a four-factor and three-level orthogonal experiment, and structure compensation were implemented to address machining errors. Impact capability of the resonator and mode characterization as well as Q-value of the gyro revealing that the resonator can withstand high overload up to 15000g, frequency of working mode is 15382.2Hz and 15379.8Hz, respectively, which close to simulated result of 15443Hz exhibited high process precision. The corresponding Q-values of the driving mode and sensing mode are 817k and 819k, respectively, indicating high-performance potential.

High Overload Failure Rate Prediction Method for Packaged Devices Based on Stress–Strength Interference Modeling

High Overload Failure Rate Prediction Method for Packaged Devices Based on Stress–Strength Interference Modeling

Efficacy and safety of deferoxamine, deferasirox and deferiprone triple iron chelator combination therapy for transfusion-dependent β-thalassaemia with very high iron overload: a protocol for randomised controlled clinical trial

IntroductionDespite the improvement in medical management, many patients with transfusion-dependent β-thalassaemia die prematurely due to transfusion-related iron overload. As per the current guidelines, the optimal chelation of iron cannot be...

Poroelastic Responses of Human Brain Under Sustained High Overloads

Poroelastic Responses of Human Brain Under Sustained High Overloads

Scientific production about the Systematization of Nursing Care in the Family Health Strategy

Objective: To analyze the scientific production on the Systematization of Nursing Care (SAE) in the Family Health Strategy (ESF). Method: This is an integrative literature review. The databases chosen for the selection of studies were LILACS, MEDLINE, BDENF and ColecionaSUS accessed via VHL/BIREME, and PUBMED. Scientific articles published on the topic were included, from 2016 to 2021, and made available in full. Results: The results indicate that the predominant methods of systematizing care in the ESF include nursing consultation, the use of the International Classification for Nursing Practice (ICNP) taxonomy and the application of the Nursing Process (NP). Conclusion: Specific obstacles include lack of training, high demand overloading professionals, limitations of physical structure and deficiency of materials, lack of sensitivity about the importance of SAE, lack of definition of the nurse's role in primary care and inadequate nursing staffing.