scholarly journals A simplified cervix model in response to induction balloon in pre-labour

2021 ◽  
Author(s):  
James Andrew Smith
Keyword(s):  
The United States ◽  
Spring Constant ◽  
Endopelvic Fascia ◽  
Mechanism Model ◽  
Clinical Observations ◽  
Active Labour ◽  
Sliding Joint ◽  
Softening Process ◽  
Spring Constants ◽  
Simulation Time

Background: Induction of labour is poorly understood even though it is performed in 20% of births in the United States. One method of induction, the balloon dilator applied with traction to the interior os of the cervix, engages a softening process, permitting dilation and effacement to proceed until the beginning of active labour. The purpose of this work is to develop a simple model capable of reproducing the dilation and effacement effect in the presence of a balloon. Methods: The cervix, anchored by the uterus and the endopelvic fascia was modelled in pre-labour. The spring-loaded, double sliding-joint, double pin-joint mechanism model was developed with a Modelica-compatible system, MapleSoft MapleSim 6.1, with a stiff Rosenbrock solver and 1E-4 absolute and relative tolerances. Total simulation time for pre-labour was seven hours and simulations ended at 4.50 cm dilation diameter and 2.25 cm effacement. Results: Three spring configurations were tested: one pin joint, one sliding joint and combined pin-joint-sliding-joint. Feedback, based on dilation speed modulated the spring values, permitting controlled dilation. Dilation diameter speed was maintained at 0.692 cm · hr−1 over the majority of the simulation time. In the sliding-joint-only mode the maximum spring constant value was 23800 N · m−1. In pin-joint-only the maximum spring constant value was 0.41 N·m· rad−1.With a sliding-joint-pin-joint pair the maximum spring constants are 2000 N · m−1 and 0.41 N · m · rad−1, respectively. Conclusions: The model, a simplified one-quarter version of the cervix, is capable of maintaining near-constant dilation rates, similar to published clinical observations for pre-labour. Lowest spring constant values are achieved when two springs are used, but nearly identical tracking of dilation speed can be achieved with only a pin joint spring. Initial and final values for effacement and dilation also match published clinical observations. These results provide a framework for development of electro-mechanical phantoms for induction training, as well as dilator testing and development.

scholarly journals A simplified cervix model in response to induction balloon in pre-labour

2021 ◽  
Author(s):  
James Andrew Smith
Keyword(s):  
The United States ◽  
Spring Constant ◽  
Endopelvic Fascia ◽  
Mechanism Model ◽  
Clinical Observations ◽  
Active Labour ◽  
Sliding Joint ◽  
Softening Process ◽  
Spring Constants ◽  
Simulation Time

Background: Induction of labour is poorly understood even though it is performed in 20% of births in the United States. One method of induction, the balloon dilator applied with traction to the interior os of the cervix, engages a softening process, permitting dilation and effacement to proceed until the beginning of active labour. The purpose of this work is to develop a simple model capable of reproducing the dilation and effacement effect in the presence of a balloon. Methods: The cervix, anchored by the uterus and the endopelvic fascia was modelled in pre-labour. The spring-loaded, double sliding-joint, double pin-joint mechanism model was developed with a Modelica-compatible system, MapleSoft MapleSim 6.1, with a stiff Rosenbrock solver and 1E-4 absolute and relative tolerances. Total simulation time for pre-labour was seven hours and simulations ended at 4.50 cm dilation diameter and 2.25 cm effacement. Results: Three spring configurations were tested: one pin joint, one sliding joint and combined pin-joint-sliding-joint. Feedback, based on dilation speed modulated the spring values, permitting controlled dilation. Dilation diameter speed was maintained at 0.692 cm · hr−1 over the majority of the simulation time. In the sliding-joint-only mode the maximum spring constant value was 23800 N · m−1. In pin-joint-only the maximum spring constant value was 0.41 N·m· rad−1.With a sliding-joint-pin-joint pair the maximum spring constants are 2000 N · m−1 and 0.41 N · m · rad−1, respectively. Conclusions: The model, a simplified one-quarter version of the cervix, is capable of maintaining near-constant dilation rates, similar to published clinical observations for pre-labour. Lowest spring constant values are achieved when two springs are used, but nearly identical tracking of dilation speed can be achieved with only a pin joint spring. Initial and final values for effacement and dilation also match published clinical observations. These results provide a framework for development of electro-mechanical phantoms for induction training, as well as dilator testing and development.

The Appropriate Lumped Constants of Vibrating Shaft Systems

1943 ◽  
Vol 10 (4) ◽  
pp. A220-A224
Author(s):  
G. Horvay ◽  
J. Ormondroyd
Keyword(s):  
Total Mass ◽  
Spring Constant ◽  
New Method ◽  
Concentrated Mass ◽  
Shaft System ◽  
Spring Constants

Abstract The present paper is a theoretical supplement to the descriptive article, “Static and Dynamic Spring Constants.” It is concerned with the derivation of the constants (1a)Ki=ki+16miω2=ki(1+16ϵi2)(ϵi2=ω2mi/ki)(1b)Mi=μi+12(mleft+mright) of the appropriately lumped shaft system (Section 1), and with an estimate of the range of the new method (Sections 2, 3, 4). Term ki denotes the distributed static spring constant, mi the total mass of the ith (uniform) shaft section of the system; μi is the ith concentrated mass, ω the frequency of vibration.

Evaluation of bridge support condition using bridge responses

2018 ◽  
Vol 18 (3) ◽  
pp. 767-777 ◽  
Author(s):  
Young-Soo Park ◽  
Sehoon Kim ◽  
Namgyu Kim ◽  
Jong-Jae Lee
Keyword(s):  
Sensitivity Analysis ◽  
Numerical Analysis ◽  
Field Test ◽  
Laboratory Tests ◽  
Spring Constant ◽  
Scale Model ◽  
Support Condition ◽  
Bridge Responses ◽  
Spring Constants

This article presents a method for evaluating the support condition of bridges. This is done by representing the aging and deteriorated supports as rotation springs with equivalent spring constants. Sensitivity analysis was performed to obtain a relationship between the spring constant and the bridge responses (deflections/slopes). From this relationship, measured bridge responses can be used to estimate the equivalent spring constants through interpolation. Numerical analysis was performed to check whether the method can be used to calculate equivalent spring constants. Then, the method was verified by performing laboratory tests on a scale model bridge and field test on an actual bridge. In both tests, spring constants were estimated using the proposed method and then verified by calculating the displacements and frequencies and comparing them to the measured values.

Experimental Study for Identifying Stiffness of Bridge Slab by Using Wavelet Transform

2006 ◽  
Author(s):  
Naoto Imanishi ◽  
Akira Sone ◽  
Arata Masuda
Keyword(s):  
Experimental Study ◽  
Wavelet Transform ◽  
Reinforced Concrete ◽  
Health Monitoring ◽  
Spring Constant ◽  
Acceleration Response ◽  
Graphic Form ◽  
Noisy Conditions ◽  
Excitation Force ◽  
Spring Constants

In health monitoring of bridge slabs, it is suitable to identify the change in their stiffness. The authors have been proposing the method to identify the spring constant of slab by wavelet transform of an excitation force and acceleration response. In previous paper, the method to identify the spring constants of slabs is theoretically investigated under the noisy conditions. The method to find the specific values of constant α in an analyzing wavelet by which the most reliable value of the spring constant is given according to the graphic form showing the relation between identified mass and constant α. In this paper, the effectiveness of the method is proven from the experiment results using the reinforced concrete panel specimen.

Stiffness and Damping of Thin PFPE Lubricant Bridging Between Magnetic Disk and Diamond Probe Tip

2007 ◽  
Vol 129 (4) ◽  
pp. 720-728 ◽  
Author(s):  
Yasunaga Mitsuya ◽  
Yasuji Ohshima ◽  
Hedong Zhang ◽  
Kei Aoyama ◽  
Toshiyuki Kawai ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Disk Surface ◽  
Spring Constant ◽  
Damping Coefficient ◽  
Curvature Radius ◽  
Magnetic Disk ◽  
Pfpe Lubricant ◽  
Stiffness And Damping ◽  
Diamond Probe ◽  
Spring Constants

Spring constants and damping coefficients of a thin lubricant bridge of a perfluoropolyether (PFPE) lubricant intervening between a diamond probe tip and a diamond-like carbon (DLC) surface of a magnetic disk are identified through regression analysis of tip damping vibration. PFPE lubricants with functional end groups were used to form a lubricant bridge between the DLC surface and a probe tip with a notably small curvature radius of 0.1μm. The tip was both retracted from and extended toward the disk surface at four different progressive distances to attain varied elongation of the bridge. It was also vibrated at each step to provide damping waveforms. By applying regression analysis to the observed waveforms, the spring constant and the damping coefficient of the lubricant bridge were identified within an elongation range from 50nm to 800nm. Spring constant of the lubricant bridge kb had a negative value varying from −0.15N∕m to −0.1N∕m. The damping value expressed in the form of frequency-multiplied damping cb×ω ranged from 0.02N∕m to 0.06N∕m. Note that both the absolute value of spring constant ∣kb∣ and frequency-multiplied damping cb×ω exhibited U-shaped variation with lubricant bridge elongation; that is, those values decrease with bridge elongation and they begin to increase after reaching the minimum. The variation in the spring constant was found to be in good accordance with the quasi-static stiffness of the lubricant bridge, and variation in the damping coefficient was explained by energy loss arising in the vibrating lubricant bridge.

scholarly journals Study on the Model Construction of Power Transfer Movement from the Perspective of China`s International Relations

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Baixu Duan ◽  
Jia Tang
Keyword(s):  
United States ◽  
Cold War ◽  
Soviet Union ◽  
International Relations ◽  
The United States ◽  
Mechanism Model ◽  
The Soviet Union ◽  
Modelling Analysis ◽  
Short Period ◽  
International Power

Power plays a fundamental role in the system in the international relations. Basie on Game Theory, and by the assumption that the total amount of power is relatively constant in a short period of time, this paper makes a modelling analysis of the "take-and-give" movement of power among rational countries. Based on building the curve of power taken and the curve of power given, the power balance mechanism model and the power movement track model are constructed. We also make an analysis and by the examples. In the current situation, this paper agrees with the view of most scholars. China and the United States have opened a "cold war" different from the United States and the Soviet Union. With the coordination between the PRC-US relations, it is concluded that a stable international power mechanism requires the active cooperation of all countries, which could promote the power operation to reach the equilibrium point. The analysis method of power movement can explain the cause, progress, and trend of Sino US cold war to a certain extent.

scholarly journals The Use of Parallel Computing to Accelerate Fire Simulations for Cultural Heritage Buildings

2020 ◽  
Vol 12 (23) ◽  
pp. 10005
Author(s):  
Yu-Hsiang Huang
Keyword(s):  
Risk Factors ◽  
Factor Analysis ◽  
Risk Factor ◽  
Cultural Heritage ◽  
The United States ◽  
Simulation Software ◽  
Risk Factor Analysis ◽  
Spread Model ◽  
Heritage Buildings ◽  
Simulation Time

This study proposes an optimization design to improve the accuracy of fire risk models by combining the results of the UFSM (Urban Fire Spread Model, Japan) with the United States (US) Fire Simulation Software FDS6.7.3 (Fire Dynamics Simulator, FDS). Using parallel processing, the simulation time was dramatically reduced, and this may assist the risk factor analysis of buildings in a large area. Fire destroyed all seven main structures of the Shuri Castle World Heritage site on 31 October 2019, and this tool may have identified risk factors, which could have been mitigated and potentially prevented the building loss. Other historical buildings may benefit from using this tool to identify their relevant risk factors. This study completed a full-scale simulation of the 76 m × 45 m × 15 m area, which contained the nine temples, with 6.4 million grids for a simulation time of 600 s in 45 h. This tool can assist in input-data risk factor analysis and contribute to the improvement of protection technology for cultural heritage buildings.

Determination of Spring Constant for Simulating Deformable Object under Compression

2009 ◽  
Vol 417-418 ◽  
pp. 369-372
Author(s):  
Koeng Wook Ko ◽  
Hyun Soo Kim ◽  
Sung In Bae ◽  
Eui Seok Kim ◽  
Yuan Shin Lee
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Spring Constant ◽  
Deformable Objects ◽  
Spring Model ◽  
Mass Spring Model ◽  
Spring System ◽  
Mass Spring ◽  
Spring Constants

It is not easy to simulate realistic mechanical behaviors of elastically deformable objects with most existing mass-spring systems for their lack of simple and clear methods to determine spring constants considering material properties (e.g. Young's modulus, Poisson’s ratio). To overcome this obstacle, we suggest an alternative method to determine spring constants for mechanical simulation of deformable objects under compression. Using the expression derived from proposed method, it is possible to determine one and the same spring constant for a mass-spring model depending on Young's modulus, geometric dimensions and mesh resolutions of the 3-D model. Determination of one and the same spring constant for a mass-spring model in this way leads to simple implementation of the mass-spring system. To validate proposed methodology, static deformations (e.g. compressions and indentations) simulated with mass-spring models and FEM reference models are compared.

Effect of Box Microspring Size on Spring Constant

2008 ◽  
Vol 33-37 ◽  
pp. 975-980
Author(s):  
Cho Chun Wu ◽  
Rong Shun Chen ◽  
Meng Ju Lin
Keyword(s):  
Exponential Decay ◽  
Rate Of Change ◽  
Spring Constant ◽  
Limit Value ◽  
Symmetric Structure ◽  
Constant Rate ◽  
Spring Constants

There are two kinds of microsprings often used: box microsprings and zig-zag (serpentine) microsprings. Box microsprings are considered with larger spring constant k and more symmetric structure keeping balance than zig-zag microspring. Density of spring number, N, is defined as the numbers of turns within a constant total spring length to investigate performance of box microspring. With applying the same force, the relation between spring constants and microspring sizes are discussed. Under different size parameters of box microsprings: B, W, T, and L, the spring constants decrease like exponential decay and approach a limit value as density of spring number increasing. The results show density of spring number has significant effect on spring constant. Rate of change on spring constant, Kt, is defined as the ratio of spring constant between N=1 and N=10. It means normalization of spring constant that increase density of spring number from minimum to maximum. The results show Kt decreases when B and W increase and increase as T and L increasing. Therefore, the spring constant is coupled affected by different size parameters due to different tendency as results shown. Such that the results can apply in microspring design by adjusting these size parameters to obtain the spring constant.

scholarly journals Coccidioidomycosis A Cause of Sarcoidosis

2017 ◽  
Vol 4 (3) ◽  
Author(s):  
Tim Kuberski ◽  
Isaac Yourison
Keyword(s):  
United States ◽  
Lung Biopsy ◽  
Deoxyribonucleic Acid ◽  
Case Reports ◽  
The United States ◽  
Unknown Etiology ◽  
Chain Reaction ◽  
Clinical Observations ◽  
Polymerase Chain ◽  
Endemic Fungi

Abstract Background Sarcoidosis is a granulomatous disease of unknown etiology and coccidioidomycosis is a granulomatous fungal infection endemic to the southwestern United States. Clinical observations on patients with sarcoidosis and coccidioidomycosis simultaneously led to the hypothesis that sarcoidosis can be caused by the fungus Coccidioides. Methods Two patients with sarcoidosis and coccidioidomycosis were studied, one prospectively (ie, a patient with sarcoidosis was predicted to develop coccidioidomycosis) and the other retrospectively (ie, a patient with coccidioidomycosis develops sarcoidosis). In addition, a literature review found 5 patients with these 2 diseases, and they were analyzed to establish an archived relationship between the 2 entities. In addition, polymerase chain reaction (PCR) testing for Coccidioides deoxyribonucleic acid (DNA) was performed on tissue from 15 Arizona patients diagnosed with sarcoidosis. Results Patient 1 was diagnosed with sarcoid in Arizona and followed prospectively. There was no evidence for coccidioidomycosis at diagnosis. This patient was observed for 8 years before he was documented to have disseminated coccidioidomycosis. Patient 2 was retrospectively studied. He was diagnosed with disseminated coccidioidomycosis, but after 3 years, while on antifungal therapy, he developed respiratory failure. A lung biopsy was consistent with sarcoidosis with no evidence of Coccidioides; cultures, histopathology, and serology were all negative. Paradoxically, PCR testing for Coccidioides DNA on tissue taken at the time of the sarcoidosis diagnosis were all negative, including Patient 2 who had proven coccidioidomycosis. Conclusions The 2 study patients and 5 case reports from the literature support the hypothesis that Coccidioides can cause sarcoidosis in Arizona. There are similar reports in the literature that Histoplasma can be associated with sarcoidosis. Based on these observations, we propose that sarcoidosis can be caused by endemic fungi in different areas of the United States, coccidioidomycosis in the Southwest and histoplasmosis in the Midwest.

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