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Journal articles on the topic 'Changing preload'

Author: Grafiati

Published: 14 March 2023

Last updated: 31 July 2025

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1

Wu, Qiong, Lei Li, and Yi-Du Zhang. "Simulations and Experiments on Vibration Control of Aerospace Thin-Walled Parts via Preload." Shock and Vibration 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/8135120.

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Thin-walled parts primarily comprise the entire piece of rough machining, and the material removal rate can surpass 95%. Numerous components with thin-walled structures are preferred in the aerospace industry for their light weight, high strength, and other advantages. In aerospace thin-walled workpiece machining processes and practical applications, they are excited by the vibration. The preload changing the modal stiffness of the part is found and this change causes continuous changes in the natural frequency. Researching on the influence of pretightening force on dynamic characteristics of

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2

Xia, Zhongxian, Yuhou Wu, Hua Wei, et al. "Experimental Research on the Influence of Working Conditions on Vibration and Temperature Rise of Si3N4 Full-Ceramic Bearing Motors." Shock and Vibration 2021 (November 8, 2021): 1–16. http://dx.doi.org/10.1155/2021/1176566.

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Working conditions such as lubrication, preload, and rotational speed have important influence on vibration and temperature rise of the spindle motor. In this study, controlled variable experiments are carried out on the silicon nitride (Si3N4) full-ceramic ball bearing and steel bearing of the same type, and the vibration signal characteristics and temperature rise of the spindle motor are tested and analysed, by changing the lubrication conditions, preloads, and rotational speeds of the spindle motor. Through the research, it is found that as the rotational speed increases, the vibration vel

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3

Li, Xiao-hu, Yan-fei Zhang, Jun Hong, Hong Zhao, and Huan-feng Li. "Experiment analysis of spindle performance with rolling bearing under non-uniform preload." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 17 (2016): 3135–46. http://dx.doi.org/10.1177/0954406215605867.

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As a result of the manufacturing errors in the main parts of spindle, and the errors in assembly process of spindle, as well as the non-uniform heat distribution during spindle operation, the non-uniformly distributed preload in rolling bearing is inevitable. The non-uniform preload has not only axial force on the rolling bearing, but also the bending moment around the rolling bearing center. The effect of preload in bearing being non-uniform on the spindle performance is still unclear. In order to analyze the spindle performance with rolling bearing under non-uniform preload, a spindle test s

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4

Chen, Kai, Li Zu, and Li Wang. "Prediction of preload attenuation of ball screw based on support vector machine." Advances in Mechanical Engineering 10, no. 9 (2018): 168781401879916. http://dx.doi.org/10.1177/1687814018799161.

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Ball screw is a mechanical device widely used in mechanical field. The reverse clearance of ball screw will reduce its precision. In order to eliminate the reverse clearance, it is necessary to apply preload to the ball screw. It is very difficult to measure the preload in real time, and the data are large and time-consuming. By using machine learning method to predict and supervise preload, the changing trend of working condition of ball screw can be evaluated in advance, and the working precision of screw is controlled, which has important engineering significance. In this article, the relat

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Scallan, Joshua P., John H. Wolpers, Mariappan Muthuchamy, David C. Zawieja, Anatoliy A. Gashev, and Michael J. Davis. "Independent and interactive effects of preload and afterload on the pump function of the isolated lymphangion." American Journal of Physiology-Heart and Circulatory Physiology 303, no. 7 (2012): H809—H824. http://dx.doi.org/10.1152/ajpheart.01098.2011.

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We tested the responses of single, isolated lymphangions to selective changes in preload and the effects of changing preload on the response to an imposed afterload. The methods used were similar to those described in our companion paper. Step-wise increases in input pressure (Pin; preload) over a pressure range between 0.5 and 3 cmH2O, at constant output pressure (Pout), led to increases in end-diastolic diameter, decreases in end-systolic diameter, and increases in stroke volume. From a baseline of 1 cmH2O, Pin elevation by 2–7 cmH2O consistently produced an immediate fall in stroke volume t

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6

ZANNOLI, ROMANO, IVAN CORAZZA, PAOLA CACCIAFESTA, and ANGELO BRANZI. "EVALUATING THE MECHANICAL BEHAVIOR OF A VENTRICULAR SIMULATOR." Journal of Mechanics in Medicine and Biology 05, no. 02 (2005): 369–73. http://dx.doi.org/10.1142/s0219519405001503.

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The mechanical performance of a ventricular simulator was characterized by recording Pressure-Volume loops for different preload and afterload conditions. The End Systolic Pressure-Volume Relationship was drawn to demonstrate a "physiological" behaviour. The external work of the artificial ventricle was calculated by the P-V loop area and the presence of the Frank–Starling mechanism was demonstrated. The P-V loop was obtained by recording the internal pressure and by integrating the flow signal recorded at the orifice of the artificial ventricular chamber. The preload was modified by increasin

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7

Turek, Paweł. "Optimization of the Control Algorithm for an Active Bearing Support." Applied Sciences 14, no. 2 (2024): 824. http://dx.doi.org/10.3390/app14020824.

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This article presents a spindle system with an active bearing support for which the author proposed a control system based on a PID controller. This type of solution improves the mechanical properties of this spindle by changing the stiffness, which results in a wider range of permissible rotational speeds, lower power losses and an increased resistance to vibrations of the entire system. This work describes the mechanism of changing the bearing preload. During tests on a real test stand, the correct functioning of the preload control system was checked for various dynamic conditions. In this

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8

Kenny, Jon-Emile S., Ross Prager, Philippe Rola, et al. "Inferior Vena Caval Measures Do Not Correlate with Carotid Artery Corrected Flow Time Change Measured Using a Wireless Doppler Patch in Healthy Volunteers." Diagnostics 13, no. 23 (2023): 3591. http://dx.doi.org/10.3390/diagnostics13233591.

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(1) Background: The inspiratory collapse of the inferior vena cava (IVC), a non-invasive surrogate for right atrial pressure, is often used to predict whether a patient will augment stroke volume (SV) in response to a preload challenge. There is a correlation between changing stroke volume (SV∆) and corrected flow time of the common carotid artery (ccFT∆). (2) Objective: We studied the relationship between IVC collapsibility and ccFT∆ in healthy volunteers during preload challenges. (3) Methods: A prospective, observational, pilot study in euvolemic, healthy volunteers with no cardiovascular h

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9

Zhao, Yang, Yaping Xue, and Weining Lei. "Analysis of the static characteristics of magnetic preloaded small-throat gas thrust bearing rotary table." Journal of Physics: Conference Series 3009, no. 1 (2025): 012081. https://doi.org/10.1088/1742-6596/3009/1/012081.

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Abstract To make orifice-compensated aerostatic bearings stiffer, we have added permanent magnets to the design of thrust aerostatic bearings. This study looks at a type of bearing that uses air and magnets to see how changes in magnetic force, air pressure, and hole size affect the bearing’s performance. The magnetic preload force is created when permanent magnets interact with magnetic materials, using the no-current permanent magnetic field module in COMSOL. We made a simulation model to study how far the magnetic field reached. How the magnetic forces connect and how the magnetic strength

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10

Alfares, Mohammed, Omar Saleem, and Majed Majeed. "Analytical study of thermal variation impact on dynamics of a spindle bearing system." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 233, no. 4 (2019): 871–98. http://dx.doi.org/10.1177/1464419319841687.

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Changes in the thermal status of machine tools spindle-bearing system can have a noticeable effect on the performance of the machine itself, and therefore studying the thermal effect on the performance ball bearing during service is important. For this purpose, a study was carried out where a simple rotating shaft system supported by two angular contact ball bearings was taken into consideration. Heat was generated due to the contact between the balls and rings of the bearing. This thermal effect on the dynamics of the system was studied using a transient thermal model. The system was divided

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11

Md Irfan, Rajesh Kumar, and Mohit Kumar. "Effect of Suspension Preload on Fatigue Life of Two Wheeler Frame." ARAI Journal of Mobility Technology 4, no. 3 (2024): 1191–201. http://dx.doi.org/10.37285/ajmt.4.3.2.

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A suspension unit is a significant component in a vehicle. It provides a smooth ride, improves traction, maintains ride geometry and facilitates better handling. A typical suspension setup in a two-wheeler consists of a front and rear suspension setup working independently to achieve the desired function. It connects the wheel to the chassis of the vehicle, transferring road load and hence affecting the durability of the structural members. This research work focuses on the durability aspect of the suspension unit with its preload as the control parameter. A rear suspension with seven preload

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12

Yang, Xue, Chang Geng Shuai, and Shen Lin Yang. "Magnetorheological Effect of NDI Polyurethane-Based MR Elastomers." Advanced Materials Research 750-752 (August 2013): 832–35. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.832.

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The dynamic magnetorheological (MR) effects of 1,5-Naphthalene diisocyanate (NDI) polyurethane-based MR elastomers were tested by changing excitation frequency, excitation amplitude, magnetic strength, or preload. NDI polyurethane-based elastomers show high dynamic mechanical property, and were used as base material to prepare MR elastomers, whose mechanical performance and dynamic MR effect were tested. The results show that: (1) the prepared NDI polyurethane-based MR elastomers have high mechanical performance and MR effect; (2) their MR effect was reduced with the increase in excitation amp

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13

Turek, Paweł. "Spindle Bearing Preload Control Using NI MyRIO." Applied Sciences 14, no. 24 (2024): 11579. https://doi.org/10.3390/app142411579.

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The article presents an application for controlling the preload of bearings in a model spindle system. The bearing preload will be implemented using piezoelectric elements, which allow for changing the preload of bearings during spindle operation, which results in a change in the stiffness of the entire system. Such a change in stiffness allows for effective reduction of the vibration amplitudes of the spindle tip. The use of the MyRIO 1900 device from National Instruments, which was programmed using LabVIEW 2021 SP1 (32 bit), is described in detail. The effectiveness of the control algorithm

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14

Turek, Paweł, Wacław Skoczyński, and Marek Stembalski. "Controlling the preload adjustment system of bearings in the machine spindle model using the LabVIEW environment." Mechanik 92, no. 11 (2019): 698–700. http://dx.doi.org/10.17814/mechanik.2019.11.92.

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A test stand with a high speed spindle equipped with an active support, which provides the possibility of changing the preload of the bearings, was presented. The LabVIEW software environment was used for control. The benefits resulting from the use of the active system to reduce the amplitude of the vibration displacement of the spindle tip are presented.

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15

Long, Lian Chun, Zhong Ying Chen, and Zhi Guang Yang. "Research on Pre-Loaded Composite Irradiated by Laser Beam." Key Engineering Materials 462-463 (January 2011): 872–77. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.872.

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This paper investigates failure behavior tests of T300/AG80 composite laminated specimens under tensile and compressive preload using a load holding device and laser irradiation from an Nd: YAG laser. By changing the magnitudes of the preload and the power densities of the laser, the effects of preload and laser power density on the time-to-failure of the specimens were observed. The response process of specimens was synchronized taken in using high-speed camera in experiment. The experimental results showed that tensile mechanical properties of T300/AG80 composite laminated specimens were obv

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16

Brimioulle, Serge, Pierre Wauthy, Patricia Ewalenko, et al. "Single-beat estimation of right ventricular end-systolic pressure-volume relationship." American Journal of Physiology-Heart and Circulatory Physiology 284, no. 5 (2003): H1625—H1630. http://dx.doi.org/10.1152/ajpheart.01023.2002.

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Assessement of right ventricular (RV) contractility from end-systolic pressure-volume relationships (ESPVR) is difficult due to problems in measuring RV instantaneous volume and to effects of changes in RV preload or afterload. We therefore investigated in anesthetized dogs whether RV ESPVR and contractility can be determined without measuring RV volume and without changing RV preload or afterload. The maximal RV pressure of isovolumic beats (Pmax) was predicted from isovolumic portions of RV pressure during ejecting beats and compared with Pmaxmeasured during the first beat after pulmonary ar

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17

CRON, THOMAS A., PATRICK HILTI, HARTMUT SCHACHINGER, et al. "Rate Response of a Closed-Loop Stimulation Pacing System to Changing Preload and Afterload Conditions." Pacing and Clinical Electrophysiology 26, no. 7p1 (2003): 1504–10. http://dx.doi.org/10.1046/j.1460-9592.2003.t01-1-00218.x.

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18

Zhu, Bin Rong, Hai Jun Xing, and Jing Bo Yang. "Experimental and Finite Element Study on Mechanical Behavior of Bolted Joint with Bolt Clearance in Transmission Tower." Advanced Materials Research 625 (December 2012): 25–29. http://dx.doi.org/10.4028/www.scientific.net/amr.625.25.

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To accurately analyze the force and deformation of the transmission tower, it is necessary to study performance of bolted joint in the tower. In the paper single shear and double shear bolted joint with number of bolts changed is tested. Based on the actual data in test, nonlinear finite element model of bolted joint is established with ABAQUS, considering the bolt clearance and preload, and shows good agreement with test results, which is proved correct and applicable. Eventually, through a comparison of FEM and test results, the factors that affect bolt slip and the changing relationship of

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19

BAKOURI, MOHSEN, and MOHAMED YACIN SIKKANDAR. "NUMERICAL INVESTIGATION ON PRELOAD AND AFTERLOAD SENSITIVITY FOR USING VENTRICULAR ASSIST DEVICE ON HEART FAILURE PATIENTS." Journal of Mechanics in Medicine and Biology 20, no. 07 (2020): 2050042. http://dx.doi.org/10.1142/s0219519420500426.

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A left ventricular assist device (LVAD) is a surgically implanted mechanical pump being used for patients with end-stage heart failure (HF). One of the significant clinical challenges in using LVADs is its remarkable changes in hemodynamic parameters during a change in body position from supine to standing. In standing position, vasodilatation of veins occurs in the legs, which decreases left ventricular end-diastolic pressure, and, in turn, the preload to the LVAD. In this research, a numerical investigation is carried out to evaluate the effect of LVAD in cardiac hemodynamic parameters such

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20

Osakue, Edward E., and Lucky Anetor. "Design of Elastic Screw Fasteners under Tensile Load." Mechanical Engineering Research 7, no. 1 (2017): 13. http://dx.doi.org/10.5539/mer.v7n1p13.

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This paper presents an equivalent stress approach in the design of screw fasteners under tensile load. Design equations are formulated for sizing and verifying screw fastener selection. It considers axial tensile, direct shear, bending, and torsional stresses and combines them as appropriate into equivalent or effective stresses. The equivalent or effective stresses are compared with screw fastener material strength capabilities such as proof, yield, fatigue, and tensile strengths for failure assessment. Design factors are derived for assessing design adequacy the screw fastener. For elastic s

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21

Chagué, F., A. Gudjoncik, C. Richard, et al. "Effect of changing the preload on speckle-tracking-derived left ventricular contractility indexes in middle-aged ultra-trailers." Archives of Cardiovascular Diseases Supplements 9, no. 1 (2017): 57–58. http://dx.doi.org/10.1016/s1878-6480(17)30188-x.

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22

Wright, G., and E. Hurn. "Cytochalasin inhibition of slow tension increase in rat aortic rings." American Journal of Physiology-Heart and Circulatory Physiology 267, no. 4 (1994): H1437—H1446. http://dx.doi.org/10.1152/ajpheart.1994.267.4.h1437.

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We separated the K(+)-induced contraction of rat aortic rings into its initial (fast) and secondary (slow) components. It was found that temperature sensitivity, K+ depolarization, and Ca2+ dependency could each be utilized to differentiate between these two components of the contractile response. Increasing the passive tension preload of the tissue increased the fast response but had no significant effect on the secondary slow rise in tension. Cytochalasins, which inhibit actin polymerization, reversibly inhibited tension development by rat aortic rings with the effect selectively confined to

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23

Pinsky, M. R., G. M. Matuschak, L. Bernardi, and M. Klain. "Hemodynamic effects of cardiac cycle-specific increases in intrathoracic pressure." Journal of Applied Physiology 60, no. 2 (1986): 604–12. http://dx.doi.org/10.1152/jappl.1986.60.2.604.

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Changes in intrathoracic pressure (ITP) can influence cardiac performance by affecting ventricular loading conditions. Because both systemic venous return and factors determining left ventricular (LV) ejection may vary over the cardiac cycle, phasic increases in ITP may differentially affect preload or afterload if delivered at specific points within the cardiac cycle. We studied the hemodynamic effects of cardiac cycle-specific increases in ITP (pulses) delivered by a high-frequency jet ventilator in an acute closed-chested canine model (n = 11), using electromagnetic flow probes to measure b

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McDonough, K. H., R. W. Barbee, C. Dobrescu, C. H. Lang, and J. J. Spitzer. "Enhanced myocardial depression in diabetic rats during E. coli sepsis." American Journal of Physiology-Heart and Circulatory Physiology 253, no. 2 (1987): H276—H282. http://dx.doi.org/10.1152/ajpheart.1987.253.2.h276.

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The aim of this study was to determine whether diabetes enhanced the sensitivity of the myocardium to the deleterious effects of in vivo-administered Escherichia coli. Diabetes was induced in two groups of animals. One group received 70 mg/kg streptozotocin (iv) and exhibited a severe diabetes with elevated fasting and fed blood glucose concentrations and a markedly abnormal response to an oral glucose load. The second group received 45 mg/kg streptozotocin, was mildly diabetic (termed “latent” diabetes), and was characterized by normal fasting blood glucose but slightly elevated fed blood glu

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25

Xu, Zhi Qian, Xiang Zhen Yan, and Xiu Juan Yang. "Sealing Structure Design and Analysis of Non-API Pipe Connection." Applied Mechanics and Materials 34-35 (October 2010): 811–14. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.811.

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In this paper, the main design parameters of seal structure for non-API pipe connection are studied. First, as the total contact pressure consists of the radial preload generated by interference fit and the radial pressure caused by gas pressure in pipe, the variation laws of their values changing with the sealing diameter are analyzed. The sealing diameter value which maximizes the total contact pressure can be obtained from the derivation formula for calculating the total contact pressure. Second, considering the yield condition of pipe connection under the internal and the external pressure

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26

Arpesella, G., E. Mikus, M. Arabia, A. Loforte, and P. M. Mikus. "Circulatory Assist with Centrifugal Pump as a Bridge to Recovery: Mathematical Analysis." International Journal of Artificial Organs 30, no. 7 (2007): 604–10. http://dx.doi.org/10.1177/039139880703000708.

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Mechanical circulatory support is an essential issue in the management of patients with end-stage cardiac failure. The aim of this study is to evaluate the efficacy of temporary support with a centrifugal blood pump as bridge to heart function recovery or bridge to transplantation. Heart recovery is achieved by improving ventricular mechanical working conditions with proper modifications of preload and afterload. This article assesses the advantages of a novel “cardiac chambers” cannulation setting versus the traditional one, in the case of biventricular or isolated right ventricular failure.

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McDonough, K. H., V. Chen, and J. J. Spitzer. "Effect of altered thyroid status on in vitro cardiac performance in rats." American Journal of Physiology-Heart and Circulatory Physiology 252, no. 4 (1987): H788—H795. http://dx.doi.org/10.1152/ajpheart.1987.252.4.h788.

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Effect of a chronic excess or deficit of thyroid hormone on intrinsic myocardial performance in rats was assessed. Animals were thyroidectomized or treated with thyroid hormone or vehicle 6-7 wk before the study. Body weight and heart weight were decreased in the hypothyroid group, and heart weight was elevated in the hyperthyroid group. Hearts were removed from thyroidectomized, euthyroid or thyroid-treated animals and studied as isolated, perfused working heart preparations. Ventricular function curves were generated by increasing left atrial filling pressure, whereas outflow resistance was

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Matsumoto, T., Y. Mitamura, T. Shimooka, and T. Mikami. "The Effect of Left Ventricular Assist Device (Lvad) on Cardiac Reserve in Dogs." International Journal of Artificial Organs 12, no. 8 (1989): 533–38. http://dx.doi.org/10.1177/039139888901200809.

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The effect of LVAD on the preservation of cardiac reserve against ischemic damage was studied using Sarnoff's ventricular function curve. An LVAD was implanted between the canine left atrium and the aorta. Left ventricular function was measured by changing the height of the reservoir connected to the left atrium. The left ventricular function curve (LVFC) was drawn by plotting left ventricular stroke work (LVSW) against left atrial pressure (LAP). The coronary artery was occluded under a pump-on (ON group) or pump-off (OFF group). After reperfusion, measurements were repeated and changes in th

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29

Hu, Sheng-Yen, Yuan Kang, Hsin-Ming Fu, and Chao-Ping Huang. "Identification of design parameters for spool-type restrictors." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 1 (2019): 63–72. http://dx.doi.org/10.1177/1350650119854248.

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This study presents the identification method of design parameters for single-action cylindrical spool-type restrictors of hydrostatic bearing. These parameters include restriction parameter, spool displacement parameter, and spring preload. The flow rates, inlet pressures, and outlet pressures are measured to be utilized for parameter identification of single-action cylindrical spool-type restrictors by using experimental equipment. This equipment-like an open-type planar hydrostatic bearing supports a worktable for changing recess pressure by changing apply load. Then, design parameters can

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Li, Pu, and Qi Yuan. "Stress variation of a gas turbine tie-bolt rotor with Hirth serrations considering assembling and thermal effects." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 24 (2020): 4932–44. http://dx.doi.org/10.1177/0954406220932602.

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Tie-bolt rotors are commonly applied in heavy-duty gas turbines due to a better stiffness-mass ratio behavior compared to traditional integral rotors. In order to achieve a steady transformation from mechanical energy to electricity, the clamping force of the bolt is critical to keep multiple disks as a whole unit. However, the tensile stress of the bolt is changing during rotor assembly as well as operational conditions that should be considered carefully for the rotor safety. Moreover, subjected to mechanical as well as thermal loads, the stress of the rotor disks is a complicated mixture by

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Houlihan, D. F., C. Agnisola, A. R. Lyndon, C. Gray, and N. M. Hamilton. "Protein synthesis in a fish heart: responses to increased power output." Journal of Experimental Biology 137, no. 1 (1988): 565–87. http://dx.doi.org/10.1242/jeb.137.1.565.

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The effects of exercise on the rates of protein synthesis in the chambers of the trout heart were investigated in vitro and in vivo. An in vitro rainbow trout heart preparation was developed which permitted perfusion of the coronary supply to the compact region of the ventricular muscle. This preparation was used to examine the mechanical responses to preload pressures, the oxygen consumption at different power outputs and the rates of protein synthesis in the various heart components. By increasing preload pressure it was possible to double cardiac output, oxygen consumption and power output

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Ji, Hexi, Jiazhen Han, Yong Wang, et al. "Structural Optimization and Fluid–Structure Interaction Analysis of a Novel High-Speed Switching Control Valve." Actuators 14, no. 4 (2025): 163. https://doi.org/10.3390/act14040163.

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Laver fluffy is an indispensable link in the processing of laver products. After fluffing, the laver acquires an appealing color, which is conducive to better marketability. During the primary mechanical processing of laver, a valve capable of rapid opening and closing is required to ensure that the laver’s surface becomes fluffy and lustrous post-processing. However, valve products that can meet the specific requirements of laver fluffing are scarce. This study proposes a novel principle for a high-speed switching control valve. This valve can quickly turn on or cut off the high-pressure gas

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Konecny, Filip. "The Left Ventricular End-Systolic Pressure Correlation with Aortic Valve Timing; a Novel Inotropic Index Description Using a Dual Pressure Catheter." Journal of Cardiology and Clinical Management 1, no. 1 (2022): 1–16. http://dx.doi.org/10.56391/jccm.2022.1012.

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Myocardial contraction is generated by ventricular pressure in early systole by the isometric force against closed valves, as ventricle is contracting without changing volume. This initial contractile phase of cardiac cycle (early systole) is followed by rapid shortening, isotonic contraction, allowing ejection of the blood against changing LV afterload. LV is coupled to the systemic arterial pressure; hence LV ejection is closely linked to the properties of the aortic valve, aorta, and its distributing arteries. Isometric relationship in the LV was characterized using the load-dependent examp

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Liu, C. T. "Techniques for isolation and performance of the perfused guinea pig working heart." American Journal of Veterinary Research 47, no. 5 (1986): 1032–43. https://doi.org/10.2460/ajvr.1986.47.05.1032.

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SUMMARY This study demonstrated new approaches which enabled evaluating the work performance in both ventricles of an isolated guinea pig heart. By changing the right atrial filling pressure (rafp, preload) from 6 to 20 mm of Hg at a constant aortic pressure (Pa, 20 mm of Hg), cardiac output, stroke volume, aortic flow, coronary flow, cardiac work, O2 consumption, CO2 output, as well as end-diastolic ventricular, and pulmonary arterial pressures increased. Cardiac contractility and both ventricular systolic pressures reached peak values between 12 and 14 mm of Hg of rafp and then gradually dec

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35

Bonello, Philip, Michael J. Brennan, Stephen J. Elliott, Julian F. V. Vincent, and George Jeronimidis. "Designs for an adaptive tuned vibration absorber with variable shape stiffness element." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2064 (2005): 3955–76. http://dx.doi.org/10.1098/rspa.2005.1547.

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An adaptive tuned vibration absorber (ATVA) with a smart variable stiffness element is capable of retuning itself in response to a time-varying excitation frequency, enabling effective vibration control over a range of frequencies. This paper discusses novel methods of achieving variable stiffness in an ATVA by changing shape, as inspired by biological paradigms. It is shown that considerable variation in the tuned frequency can be achieved by actuating a shape change, provided that this is within the limits of the actuator. A feasible design for such an ATVA is one in which the device offers

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Zhang, Bing, and Chaodong Li. "A rabbit shaped bidirectional linear ultrasonic motor driven by single-phase signal." Review of Scientific Instruments 94, no. 4 (2023): 045002. http://dx.doi.org/10.1063/5.0142844.

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A rabbit shaped block, single-phase, linear, ultrasonic motor is proposed. The motor is 17.7 × 9.1 × 6 mm3 in size, and the overall mass is 2.3 g. The motor is designed by referring to the rabbit running mode and the principle of a Langevin vibrator concentrator. It can realize bidirectional driving without changing the constraint position. First, the basic structure of the motor is introduced, and the working principle of the motor is discussed. Then, the motion trajectory and driving force of the motor driving foot are theoretically deduced and simulated, and the simulation results are verif

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Griva, Panagiota, Emmanouil I. Kapetanakis, Orestis Milionis, Konstantina Panagouli, Maria Fountoulaki, and Tatiana Sidiropoulou. "Tidal Volume Challenge to Assess Volume Responsiveness with Dynamic Preload Indices During Non-Cardiac Surgery: A Prospective Study." Journal of Clinical Medicine 14, no. 1 (2024): 101. https://doi.org/10.3390/jcm14010101.

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Background/Objectives: The aim of this study is to assess whether changes in Pulse Pressure Variation (PPV) and Stroke Volume Variation (SVV) following a VtC can predict the response to fluid administration in patients undergoing surgery under general anesthesia with protective mechanical ventilation. Methods: A total of 40 patients undergoing general surgery or vascular surgery without clamping the aorta were enrolled. Protective mechanical ventilation was applied, and the radial artery was catheterized in all patients. The protocol began one hour after the induction of general anesthesia and

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Slinker, B. K., and S. A. Glantz. "Beat-to-beat regulation of left ventricular function in the intact cardiovascular system." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 256, no. 4 (1989): R962—R975. http://dx.doi.org/10.1152/ajpregu.1989.256.4.r962.

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A variety of regulatory mechanisms have evolved to control the heart's pump function because the cardiovascular system must continually adapt to the changing demands that body functions place on it. This regulation takes place through many physiological systems; however, fine adjustments in cardiac pumping probably require adaptations more quickly than external control mechanisms (such as the autonomic nervous system) can compensate. Thus cardiac pumping is also regulated by mechanisms intrinsic to the heart. To better understand these intrinsic control mechanisms, we studied the beat-to-beat

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Wang, Yingying, Cong Wang, Guoheng Liu, Chong Zhang, and Jianchang Li. "An Assessment Method of Sealing Performance and Stress Intensity Factors at Crack Tip of Subsea Connector Metal Sealing Rings." Energies 15, no. 13 (2022): 4680. http://dx.doi.org/10.3390/en15134680.

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Subsea connectors are of a critical part for the sealing of subsea production systems. The working environment makes cracks initiate easily on subsea connector sealing rings. In order to ensure the safety and reliability of the sealing rings, it is necessary to study the crack’s influence on them. In this study, the main parameters that may influence stress intensity factors at crack tip are discussed. The sealing requirements of the subsea connector metal sealing rings were conducted. A finite element model was established to obtain the maximum equivalent stress and maximum equivalent plastic

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Mou, Shann-Chyi. "Structure Design and Stepping Characteristics Analysis of the Biaxial Piezoelectric Actuated Stage Using a Thin-Disc Piezoelectric Actuator." Advances in Mechanical Engineering 6 (January 1, 2014): 121497. http://dx.doi.org/10.1155/2014/121497.

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In this paper, a novel thin-disc piezoelectric actuator, 4-9-9-14 piezoelectric actuator, is used to construct and drive the micro/nanometer level biaxial piezoelectric actuated stage. The 4-9-9-14 piezoelectric actuator offers a better balanced capability of forward rotation and reverse rotation than the conventional edge-driving piezoelectric actuator. The biaxial piezoelectric actuated stage structure comprises a base, a V-shaped guide rail, an optical scale measurement system, a preload adjusting structure, and a load-carrying stage. The movement signals of the piezoelectric actuated stage

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Wi, Jun-Hee, Kwang-Hee Lee, and Chul-Hee Lee. "Self-loosening of 3D printed bolted joints for engineering applications." MATEC Web of Conferences 185 (2018): 00029. http://dx.doi.org/10.1051/matecconf/201818500029.

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A bolt joint is a simple element that joins mechanical components. Self-loosening of bolted joints occurs due to the vibrations caused by motors and engines, resulting in the breakage of machines, and potentially serious safety problems. Recently, developments in 3D printing technologies have enabled the fabrication of detailed components. These technologies can be used for producing fasteners using 3D printed bolts. Many researchers have proposed a theoretical model for self-loosening of the bolt, and experimental studies on the self-loosening phenomenon have been advanced. However, studies o

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Nour, Sayed, Guifu Wu, Zheng Zhensheng, Juan C. Chachques, Alain Carpentier, and Didier Payen. "The Forgotten Driving Forces in Right Heart Failure: New Concept and Device." Asian Cardiovascular and Thoracic Annals 17, no. 5 (2009): 525–30. http://dx.doi.org/10.1177/0218492309348638.

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Background: Right heart failure is a frequent hemodynamic disturbance in pediatric cardiac patients. Besides inotropic and chronotropic drugs, fluid administration and inhaled nitric oxide, right ventricular mechanical assistance remains difficult to perform. A circulatory assist device adapted for the right heart biophysics and physiology might be more efficient. Materials and Methods: We are developing a prototype of a non-invasive cardiac assist device (CAD) for neonates and pediatrics. It is based on a pulsatile suit device covering and affecting all territories of the right heart circuit.

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Ghafoor, Abdul, Jian S. Dai, and Joseph Duffy. "Stiffness Modeling of the Soft-Finger Contact in Robotic Grasping." Journal of Mechanical Design 126, no. 4 (2004): 646–56. http://dx.doi.org/10.1115/1.1758255.

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This paper investigates the soft-finger contact by presenting the contact with a set of line springs based on screw theory, reveals the rotational effects, and identifies the stiffness properties of the contact. An elastic model of a soft-finger contact is proposed and a generalized contact stiffness matrix is developed by applying the congruence transformation and by introducing stiffness mapping of the line springs in translational directions and rotational axes. The effective stiffnesses along these directions and axes are hence obtained and the rotational stiffnesses are revealed. This hel

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Sun, Y., M. Beshara, R. J. Lucariello, and S. A. Chiaramida. "A comprehensive model for right-left heart interaction under the influence of pericardium and baroreflex." American Journal of Physiology-Heart and Circulatory Physiology 272, no. 3 (1997): H1499—H1515. http://dx.doi.org/10.1152/ajpheart.1997.272.3.h1499.

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A phenomenological model of the cardiopulmonary circulation is developed with a focus on the interaction between the right heart and the left heart. The model predicts the hemodynamic consequences of changing circulatory parameters in terms of a broad spectrum of pressure and flow waveforms. Hemodynamics are characterized by use of an electrical analog incorporating mechanisms for transseptal pressure coupling, pericardial volume coupling, intrathoracic pressure, and baroreflex control of heart rate. Computer simulations are accomplished by numerically integrating 28 differential equations tha

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Zhong, Lingwei, Haijun Wang, Xuhua Ren, and Lei Tang. "Influence of the Cyclic Loading Path on Rock Deformation Memory Effect." Geofluids 2020 (November 23, 2020): 1–14. http://dx.doi.org/10.1155/2020/8896344.

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Deformation rate analysis utilizes deformation memory effect (DME) that is one of the fundamental properties of rock, to estimate in situ stress underground. It could be influenced by the stress history which has been subjected to in the past. To understand the influence under the cyclic loading path, in the experimental study, different stress levels were applied on sandstone samples and two types of granite samples. In the theoretical investigation, the sliding friction model consisting of multiple microstructure surfaces is considered in this paper. Both experiments and the theoretical mode

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Tran, Vivian, Xin Hui Ooi, Sravan Pannala, Anna Stefanopoulou, and Jason Siegel. "(Invited) Impact of Preload Compression and Aging on High-Temperature Li-Ion Battery Pouch Cell Venting." ECS Meeting Abstracts MA2024-02, no. 26 (2024): 2078. https://doi.org/10.1149/ma2024-02262078mtgabs.

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With the increase in electrification, addressing safety concerns from emergency responders and the reverse logistics teams who handle Li-ion battery (LIB) packs at the end of life is increasingly urgent. Battery failures and thermal runaway (TR) present several risks, including fire, fire reignitions, explosions, and toxic gas. Moreover, in dense areas with electric vehicles (EV), e.g. parking lots and charging stations, thermal runaway (TR) risks can quickly spread to adjacent vehicles. A combination of early detection and controlled fast discharge can mitigate the hazards by limiting TR prop

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Piene, H., and E. S. Myhre. "Position of interventricular septum during heart cycle in anesthetized dogs." American Journal of Physiology-Heart and Circulatory Physiology 260, no. 1 (1991): H158—H164. http://dx.doi.org/10.1152/ajpheart.1991.260.1.h158.

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The impact of the transseptal pressure gradient (TSP) during the entire heart cycle has not been assessed. This study explores in anesthetized open-chest dogs the interventricular septum's relative position to the anteroposterior transverse diameter (Dap) of the left ventricle (LV). By varying preload and afterload for both LV and right ventricle (RV) and inotropy in LV, a wide range of TSP was generated. By ultrasonomicrometry the distance between the Dap and the midpoint of septum was recorded. 1) Loops of the septal-LV free-wall diameter vs. Dap showed that the LV transverse cross section i

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Prabhu, S. D., M. M. Rozek, D. R. Murray, and G. L. Freeman. "Ryanodine and left ventricular function in intact dogs: dissociation of force-based and velocity-based indexes." American Journal of Physiology-Heart and Circulatory Physiology 273, no. 3 (1997): H1561—H1568. http://dx.doi.org/10.1152/ajpheart.1997.273.3.h1561.

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After anesthesia and autonomic blockade, nine dogs chronically instrumented with left ventricular (LV) micromanometers and piezoelectric dimension crystals were studied before and after the intravenous administration of 4 micrograms/kg ryanodine, a specific inhibitor of the sarcoplasmic reticulum Ca2+ release channel. Ryanodine prolonged LV contraction and relaxation (P < 0.001) without changing heart rate, end-diastolic volume (EDV), or end-systolic pressure. Velocity-dependent mechanical parameters were significantly depressed, including the maximal rate of LV pressure rise (dP/dtmax; P &

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Calbet, José A. L., and Robert Boushel. "Assessment of cardiac output with transpulmonary thermodilution during exercise in humans." Journal of Applied Physiology 118, no. 1 (2015): 1–10. http://dx.doi.org/10.1152/japplphysiol.00686.2014.

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The accuracy and reproducibility of transpulmonary thermodilution (TPTd) to assess cardiac output (Q̇) in exercising men was determined using indocyanine green (ICG) dilution as a reference method. TPTd has been utilized for the assessment of Q̇ and preload indexes of global end-diastolic volume and intrathoracic blood volume, as well as extravascular lung water (EVLW) in resting humans. It remains unknown if this technique is also accurate and reproducible during exercise. Sixteen healthy men underwent catheterization of the right femoral vein (for iced saline injection), an antecubital vein

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Weber, Howard S. "Serial echocardiographic Doppler evaluation of diastolic function in the normal human fetus." Cardiology in the Young 6, no. 1 (1996): 32–36. http://dx.doi.org/10.1017/s1047951100003218.

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AbstractThe assessment of diastolic function in the developing fetus is difficult because of constantly changing conditions of loading. Previous reports suggesting improved ventricular compliance with fetal development are limited by the Doppler indices utilized. Using load-dependent and independent variables, we examined and compared serially right and left ventricular diastolic function in 11 normal fetuses (44 echocardiographic studies) at 22±1.0 weeks; 30±1.0 weeks; 36±1.0 weeks of gestation and 64±25 hours postnatally. Load-dependent indices included early to late time velocity integral r

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