Fluid Pulsation Research Articles

Correction to: The Role of Continuous Cerebrospinal Fluid Pulsation Stress in the Remodeling of Artificial Vertebral Laminae: A Comparison Experiment by Li L, He Y, Chen X, Dong Y. Tissue Eng Part A 2019;25(3-4):203-213. DOI: 10.1089/ten.tea.2018.0100.

Tissue Engineering Part AVol. 25, No. 15-16 CorrectionsFree AccessCorrection to: The Role of Continuous Cerebrospinal Fluid Pulsation Stress in the Remodeling of Artificial Vertebral Laminae: A Comparison Experiment by Li L, He Y, Chen X, Dong Y. Tissue Eng Part A 2019;25(3–4):203–213. DOI: 10.1089/ten.tea.2018.0100Published Online:5 Aug 2019https://doi.org/10.1089/ten.tea.2018.0100.correxAboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail In the February 2019 issue of Tissue Engineering, Part A (vol. 25, no. 3-4; 203–213) the article entitled “The Role of Continuous Cerebrospinal Fluid Pulsation Stress in the Remodeling of Artificial Vertebral Laminae: A Comparison Experiment” by Li et al. requires correction.A grant in the Acknowledgment section was incorrectly listed. The original Acknowledgment read:Acknowledgments“The study was supported by National Natural Science Foundation of China (H0606); by Natural Science Foundation of Minhang District, Shanghai (2014MHZ004); and by the Foundation of Shanghai Municipal Commission of Health and Family Planning (20134305).”The Acknowledgment should have read:AcknowledgmentThe study was supported by National Natural Science Foundation of China (Grant No. 81672179); by Natural Science Foundation of Minhang District, Shanghai (2014MHZ004); and by the Foundation of Shanghai Municipal Commission of Health and Family Planning (20134305).The online version of the article has been corrected to reflect this. The authors apologize for this error.FiguresReferencesRelatedDetails Volume 25Issue 15-16Aug 2019 InformationCopyright 2019, Mary Ann Liebert, Inc., publishersTo cite this article:Correction to: The Role of Continuous Cerebrospinal Fluid Pulsation Stress in the Remodeling of Artificial Vertebral Laminae: A Comparison Experiment by Li L, He Y, Chen X, Dong Y. Tissue Eng Part A 2019;25(3–4):203–213. DOI: 10.1089/ten.tea.2018.0100.Tissue Engineering Part A.Aug 2019.1190-1190.http://doi.org/10.1089/ten.tea.2018.0100.correxPublished in Volume: 25 Issue 15-16: August 5, 2019PDF download

Experimental and theoretical study on a novel multi-dimensional vibration isolation and mitigation device for large-scale pipeline structure

The pipeline structure is prone to multi-dimensional vibration under the effect of external excitation, fluid pulsation and water hammer, which influences transportation efficiency and leads to accidents. In this paper, the multi-dimensional vibration isolation and mitigation device (MVIMD) is developed, which controls the vibration of the pipeline structure from two aspects simultaneously: isolating vibration and mitigating vibration. The device which consists of viscoelastic (VE) bearing, VE dampers and U-shaped springs, has energy dissipation capacities both in horizontal and vertical vibration due to employing VE material with high energy dissipation capacity. In order to investigate the mechanical properties of the device in the horizontal and vertical directions, the characterization tests under different frequencies and amplitudes are carried out. To accurately describe the nonlinear characteristics of the device caused by the complex viscoelasticity, the mathematical model for MVIMD is proposed for considering the effects of frequency and displacement amplitude based on the equivalent standard solid model. Finally, the numerical results are compared with the experimental data. It can be shown from comparison results that the proposed model can describe the properties of MVIMD precisely.

Http://izvuzmash.ru/catalog/avroc/airc/1649.html

Hydrodynamic analysis with the aid of numerical modeling tools is widely used in the design and modernization of hydraulic systems of aircraft, as well as in the analysis of the causes of depressurization, local destruction, and so on. This analysis includes both the operation of the hydraulic system in different modes, and the process of switching from one mode to another. However, in the scientific literature there is no information that would take account of high-frequency pressure pulsations from the hydraulic pump in the dead-end lines of hydraulic systems, and their possible impact on the pipelines and attachment points to the elements of the airframe. In the scope of this research, the possibility of low-frequency resonance in the dead-end lines of hydraulic systems is determined. A technique for setting and performing finite-volume modeling and hydro-gasdynamic analysis is described. The results of the analysis of the eigenfrequencies of oscillations in prefabricated structures of the hydraulic system pressure lines are presented. It is proven that the frequency of the resulting low-frequency resonance of the hydraulic fluid pulsations does not correspond to any of the eigenfrequencies of oscillations of the structural elements, and is, therefore, forced. The need for further assessment of the degree of influence of the described phenomenon on the operational life of the attachment points to the elements of the airframe is highlighted.

Study on dynamic characteristics of the bladder fluid pulsation attenuator based on dynamic mesh technology

Fluid-flow and pressure fluctuation are main causes of vibration and noise in liquid-conveying pipeline. As a crucial auxiliary component of liquid-conveying pipeline, the bladder pressure fluctuation attenuator plays an important role in absorbing fluctuations. According to the working condition, reasonable selection of attenuator parameters can give full play to the maximum efficiency of the attenuator so as to reduce pressure fluctuation of the pipeline. Based on the stress model of the attenuator, the mathematical and simulation models of the attenuation device are established by suitable hypothesis and simplification, and based on the calculation and physical models provided by FLUENT software, the movement of bladder was simulated by dynamic mesh and UDF (user-defined function). The absorption effect of attenuator on pipeline pressure fluctuation was investigated under different inflating pressures and frequencies. The results show that reasonable selection of initial pressure of the attenuator can effectively reduce the pressure fluctuation of pipeline fluid. Compared with the theoretical analysis results, the simulation results are more close to the experimental results, and the validity of the simulation model is verified, and a method and new idea are provided for the future study of the parameters of the bladder pressure fluctuation attenuator.

Post-contrast T1-weighted spine 3T MRI in children using a golden-angle radial acquisition.

MRI methods that have reduced sensitivity to motion are attractive in pediatric applications. In spine imaging, physiologic motion such as respiration and cerebrospinal fluid pulsation can hamper diagnostic image quality. We compare a 3D T1-weighted non-Cartesian radial acquisition with a conventional Cartesian 2D turbo-spin-echo (TSE) acquisition in axial post-contrast spine imaging at 3T. Thirty-two patients (mean age 12.2 ± 5.3years) scheduled for routine clinical spine exams with contrast were enrolled. Three pediatric neuroradiologists compared the two sequences and assessed the presence of motion, the conspicuity of nerve roots, and whether one of the sequences was preferred in visualizing pathology using Likert scales. The Fleiss' kappa statistic for inter-rater agreement was 0.29 (95% confidence interval, 0.15-0.43) for the presence of motion, 0.30 (0.21-0.38) for conspicuity, and 0.37 (0.19-0.55) for sequence preference. Radial images were less sensitive to motion than TSE (p < 0.01). Motion and consequent artifacts were present in all TSE cases, while it was absent in 51% of the radial cases. In depicting nerve roots, radial images were superior in the cervical (p < 0.05), thoracic (p < 0.01), and lumbar spines (p < 0.01). Lastly, in 28 of the 32 patients who demonstrated contrast-enhancing pathology, radial images were preferred in 51% of the cases, while both sequences were equally preferred in 41% of the cases. We demonstrate the potential utility of radial MRI in post-contrast spine imaging. The free-breathing method is robust in generating diagnostic image quality and is superior in visualizing nerve roots and extramedullary metastases than traditional Cartesian TSE acquisitions.

Clinical Significance of the CSF Pulsation Flow Sign in the Foramen of Monro on FLAIR in Patients with Aneurysmal SAH -Preliminary Report.

It is known that the cerebrospinal fluid (CSF) pulsation flow sign in the lateral ventricles directly above the foramen of Monro (CPF-M) on axial fluid attenuated inversion recovery (FLAIR) is a normal physiological finding as an artifact of FLAIR. In this study, whether CPF-M can be used as a neuroradiological finding related to pathological conditions in patients with acute aneurysmal subarachnoid hemorrhage (aSAH) was investigated. CPF-M-related clinical features were retrospectively evaluated in 147 aSAH patients who underwent adequate serial MRI examinations without massive intraventricular hemorrhage (IVH) of the lateral ventricle within 48 h of ictus. The frequency of the CPF-M in the control group was 32% (57/178), 33% (40/123), and 38% (45/117) for the normal control, chronic cerebral infarction, and deep white matter lesion (WML) groups, respectively. In aSAH patients, the overall prevalence of the CPF-M was 57% (84/147), significantly higher than in the three control groups. Multivariate analysis showed that age <70 years, lower IVH Hijdra score of the fourth ventricle, absence of T1-FLAIR mismatch, deep WMLs, old infarction, diffuse brain swelling, symptomatic delayed cerebral ischemia (DCI), shunt-dependent chronic hydrocephalus (SDCH), and favorable outcome were significantly associated with the CPF-M. Although limited to SAH patients without massive IVH of the lateral ventricles, one can conclude that, in acute aSAH, the presence of CPF-M on admission MRI suggests that the circulatory dynamics of the CSF from the basal cistern to the ventricles are approximately normal. Thus, this finding may appear to offer an indicator of a good outcome without DCI and SDCH.

Research Status of Active Control of Hydraulic Fluid Pulsation

Research Status of Active Control of Hydraulic Fluid Pulsation

Practical applications of CISS MRI in spine imaging

Routine magnetic resonance imaging evaluation of the spine is often limited by low spatial resolution and artifacts resulting from cerebrospinal fluid pulsation. Balanced steady-state free precession sequences can supplement routine spin echo sequences and provide exquisite anatomic detail and high cerebrospinal fluid-to-soft tissue contrast, adding significant diagnostic value to the evaluation of a wide variety of spine disorders.

The Role of Continuous Cerebrospinal Fluid Pulsation Stress in the Remodeling of Artificial Vertebral Laminae: A Comparison Experiment.

In this study, we designed a comparison study to investigate the effect of continuous cerebrospinal fluid pulsation (CSFP) stress on the remodeling of artificial vertebral laminae, and we found that the continuous CSFP stress played an important role in the physiological reconstruction of artificial vertebral laminae by promoting the remodeling abilities of tissue-engineered laminae (TEL). It deepens our understanding of the in vivo development of TEL, and the impact of biomechanical stimuli on the osteogenesis and remodeling.

Robust spinal cord resting-state fMRI using independent component analysis-based nuisance regression noise reduction.

Physiological noise reduction plays a critical role in spinal cord (SC) resting-state fMRI (rsfMRI). To reduce physiological noise and increase the robustness of SC rsfMRI by using an independent component analysis (ICA)-based nuisance regression (ICANR) method. Retrospective. Ten healthy subjects (female/male = 4/6, age = 27 ± 3 years, range 24-34 years). 3T/gradient-echo echo planar imaging (EPI). We used three alternative methods (no regression [Nil], conventional region of interest [ROI]-based noise reduction method without ICA [ROI-based], and correction of structured noise using spatial independent component analysis [CORSICA]) to compare with the performance of ICANR. Reduction of the influence of physiological noise on the SC and the reproducibility of rsfMRI analysis after noise reduction were examined. The correlation coefficient (CC) was calculated to assess the influence of physiological noise. Reproducibility was calculated by intraclass correlation (ICC). Results from different methods were compared by one-way analysis of variance (ANOVA) with post-hoc analysis. No significant difference in cerebrospinal fluid (CSF) pulsation influence or tissue motion influence were found (P = 0.223 in CSF, P = 0.2461 in tissue motion) in the ROI-based (CSF: 0.122 ± 0.020; tissue motion: 0.112 ± 0.015), and Nil (CSF: 0.134 ± 0.026; tissue motion: 0.124 ± 0.019). CORSICA showed a significantly stronger influence of CSF pulsation and tissue motion (CSF: 0.166 ± 0.045, P = 0.048; tissue motion: 0.160 ± 0.032, P = 0.048) than Nil. ICANR showed a significantly weaker influence of CSF pulsation and tissue motion (CSF: 0.076 ± 0.007, P = 0.0003; tissue motion: 0.081 ± 0.014, P = 0.0182) than Nil. The ICC values in the Nil, ROI-based, CORSICA, and ICANR were 0.669, 0.645, 0.561, and 0.766, respectively. ICANR more effectively reduced physiological noise from both tissue motion and CSF pulsation than three alternative methods. ICANR increases the robustness of SC rsfMRI in comparison with the other three methods. 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1421-1431.

Physiological noise reduction algorithms for fMRI data

This article describes various approaches for excluding and recognizing artifacts in functional magnetic resonance data. Similar methods can be applied to intractable artifacts, such as breathing and pulse artifacts, from white matter and cerebrospinal fluid pulsations. In this paper, using real experimental data various algorithms and approaches that can be applied not only to standard echo-planar mri-sequences, but also to ultra fast sequences are shown. Such methods make it possible for researchers to reveal only the actual human brain activity and more accurately talk about zones of functionality for certain cognitive tasks.

Fault diagnosis and location of the aero-engine hydraulic pipeline based on Kalman filter

The hydraulic pipeline is subject to the aero-engine base excitation and the pump fluid pulsation which can always damage the pipeline through overload to fatigue. So, the health monitoring techniq...

Numerical investigation of tube-side fully developed turbulent flow and heat transfer in outward corrugated tubes

A numerical study was conducted to investigate the mechanism of turbulent flow dynamics and heat transfer enhancement in novel outward corrugated tubes with a Reynolds number ranging from 3800 to 43,800 and a constant wall temperature condition. Experiments were conducted for one case of a transversely corrugated tube and five cases of a helical corrugated tube to determine the relationship between the geometric structure and flow dynamics, and the effect of the detached vortex and spiral wake on the heat transfer and pressure drop. The results show that the reasons for the heat transfer enhancement are the convective heat transfer into a jet impingement heat transfer at windward side of the corrugation and the severely turbulent fluctuation with the boundary-layer redevelopment. The rotational flow has little effect on the heat transfer enhancement; however, it inhibits the secondary flow and fluid pulsation, thereby reducing flow resistance. Moreover, the maximum values of the average Nusselt number improvement and overall heat transfer performance were 1.77 and 1.40, with Hl/D=0.10, pl/D=0.5 at Re=6260 and Hl/D=0.15, pl/D=1.0 at Re=3800, respectively. With the variation in Re, the performance evaluation criterion presents the interval optimum principle for various structure parameters, which is superior for coarse and dense corrugation under a low Re and more suitable for small and sparse corrugation under a high Re. For the whole range of Re, the cases of Hl/D=0.10, pl/D=1.5 and Hl/D=0.1, pl/D=1.0 are the better design of geometrical parameters.

Continuous versus pulsating flow boiling. Experimental comparison, visualization, and statistical analysis

This experimental study investigates an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The hypothesis is that pulsations increase the flow boiling heat transfer by means of better bulk fluid mixing, increased wall wetting, and flow-regime destabilization. The fluid pulsations are introduced by a flow modulating expansion device and are compared with continuous flow by a stepper-motor expansion valve in terms of time-averaged heat transfer coefficient. The cycle time ranges from 1 to 9 s for the pulsations. The time-averaged heat transfer coefficients are reduced from transient measurements immediately downstream of the expansion valves at low vapor qualities. The results show that the pulsations improve the time-averaged heat transfer coefficient by 3.2% on average at low cycle time (1 to 2 s), whereas the pulsations may reduce the time-averaged heat transfer coefficient by as much as 8% at high heat flux (q ⩾ 35 kW/m2) and cycle time (8 s). The latter reduction is attributed to a significant dry-out that occurs when the flow modulating expansion valve is closed. Additionally, the effect of fluid flow pulsations is found to be statistically significant, disregarding the lowest heat flux measurements.

Numerical Investigation of the FSI Characteristics in a Tubular Pump

Flow condition was simulated in a shaft tubular pump by using the Shear‐Stress Transport (SST) k‐ω turbulence model with high quality structured grids in design condition. Corresponding structural vibration characteristics were then analyzed based on two‐way coupled Fluid‐Structure Interaction (FSI) method. Fluid results showed that flow in the outlet flow passage was a combination of the axial flow and circumferential rotation motion. Time and frequency domain analysis of pressure pulsation of typical measure points indicated that larger pulsation amplitudes appeared in the tip of the blades and the main vibration source was the pressure pulsation induced by rotation of the blades. The fluid pulsation amplitudes decreased gradually along the flow direction, which can be ascribed to the function of fixed guide vane. Structural analysis of the blades in both pressure and suction side indicated that significant stress concentration was formed at the blade and hub connection near the leading edge. Maximum effective stress of the blades varied periodically, so prevention measures of the fatigue of blades should be taken. This research can provide important reference for the design of the tubular pump.

A Combined Modeling and Experimental Study Assessing the Impact of Fluid Pulsation on Charge and Energy Efficiency in Capacitive Deionization

Cell-cycling performance in capacitive deionization (CDI) can suffer from various charge-efficiency loss mechanisms. In conventional CDI, we show that salt residue within electrodes introduces a temporal lag between charge and desalination stages of a CDI cycle. Without accounting for this effect in the collection of effluent, significant performance degradation occurs as current density increases. To overcome this we use pulse-flow operation to control fresh- and brine-water concentrations. The charge and energy efficiency performance between the two flow-modes is compared using a porous electrode model that is calibrated and validated with experimental data. To quantify specific contributions to charge efficiency losses, the model captures local salt variations resulting from a combination of electrosorption, leakage current, and immobile surface charge. Compared to traditional continuous-flow operation, simulation results show that charge efficiency increases up to 23% in the pulse-flow operation at a current density up to 20 A/m2, which leads to a 73% decrease of specific energy consumption (SEC). In addition, the SEC predicted by the pulse-flow operation model closely aligns with the predictions of the continuous-flow model after accounting for the temporal lag in effluent salinity. Both simulations and experimental results suggest that pulse-flow operation closely approximates the performance in continuous-flow operation.

Heart rate and respiration influence on macroscopic blood and CSF flows.

Background Changes in blood volume in the intracranial arteries and the resulting oscillations of brain parenchyma have been presumed as main initiating factors of cerebrospinal fluid (CSF) pulsations. However, respiration has been recently supposed to influence CSF dynamics via thoracic pressure changes. Purpose To measure blood and CSF cervical flow and quantify the contribution of cardiac and respiratory cycles on the subsequent signal evolution. Material and Methods Sixteen volunteers were enrolled. All participant underwent two-dimensional fast field echo echo planar imaging (FFE-EPI). Regions of interest were placed on internal carotids, jugular veins, and rachidian canal to extract temporal profiles. Spectral analysis was performed to extract respiratory and cardiac frequencies. The contribution of respiration and cardiac activity was assessed to signal evolution by applying a multiple linear model. Results Mean respiratory frequency was 14.6 ± 3.9 cycles per min and mean heart rate was 66.8 ± 9 cycles per min. Cardiac contribution was higher than breathing for internal carotids, explaining 74.68% and 10.27% of the signal variance, respectively. For the jugular veins, respiratory component was higher than the cardiac one contributing 44.28% and 6.53% of the signal variance, respectively. For CSF, breathing and cardiac component contributed less than half of signal variance (12.61% and 23.23%, respectively). Conclusion Respiration and cardiac activity both influence fluid flow at the cervical level. Arterial inflow is driven by the cardiac pool whereas venous blood aspiration seems more due to thoracic pressure changes. CSF dynamics acts as a buffer between these two blood compartments.

CSF Pulsation Artifacts on ADC Maps Obtained with Readout-segmented EPI.

Purpose:Diffusion-weighted imaging (DWI) using readout-segmented EPI (rs-EPI) can minimize distortion and blurring artifacts; however, we sometimes encounter cerebrospinal fluid (CSF) pulsation artifacts on apparent diffusion coefficient (ADC) maps, especially when the number of readout segments (NRS) is increased. The purpose of this study was to evaluate the effect of the NRS on the CSF pulsation artifacts in the ADC maps of healthy volunteers.Methods:In 10 healthy volunteers, we obtained DWI from rs-EPI with a b-value of 0 and 1000 s/mm2. The NRS was set to 5, 7, or 9. An ADC map was generated from the trace image and the b = 0 image. Each scan was performed twice. A circular region of interest (ROI) was drawn in the pons and bilateral thalami. The standard deviation (SD) of the ROI was measured to assess the artifacts. Bilateral SD values were averaged for the ROIs in the thalami. The SD values from two successive scans of each NRS were averaged for the pons and thalami, respectively. For the qualitative analysis, the CSF pulsation artifacts on each ADC map were graded by two observers independently as 0, no artifact; 1, mild artifact; 2, moderate artifact; or 3, severe artifact.Results:In the quantitative analysis, the SD values tend to increase with the increasing of NRS in both thalami and pons; however, the difference in the SD values from each NRS did not reach a statistically significant level. In the qualitative analysis, there was a statistically significant difference in the scores between 5 and 9 segments and between 7 and 9 segments with both the observers, respectively (P < 0.05).Conclusion:The CSF pulsation artifacts on ADC maps obtained with rs-EPI are affected by the NRS.

THE ISSUE OF PULSATING FLOW IN THE SLIT OF VARIABLE HEIGHT CLEARANCES

Dynamic liquid layer is obtained in the gap of variable height. It is found total solution as the sum of the discharge currents with a constant pressure drop and oscillating components: Differential pressure pulsation and wall vibrations. The formulas for fluid pulsation rate limiting cases are obtained. The article identifies border of quasistationary model of viscous fluid from the fluid changes the dimensionless frequency of oscillations in a slot gap.

Surgical management of thoracic idiopathic spinal cord herniation. Technical case report and review

Idiopathic spinal cord herniation (ISCH) is a rare spinal disease, in which chronic cerebrospinal fluid pulsations push the arachnoid and adjacent thoracic spinal cord region through an antero-lateral dural defect of congenital, post-traumatic, or inflammatory/erosive origin. Symptomatic patients commonly present around the 5th decade of life with slowly progressive myelopathy. Diagnosis relies on high-resolution magnetic resonance imaging. Stable mild cases may be observed, whereas in progressive symptomatic situations, surgical spinal cord reposition and dural defect repair with a dural patch is the preferred treatment. We present a case of ISCH at T5/6 and a review the literature.