Nano lamellar zirconium phosphate and screw speed changing properties of melt extrusion polypropylene nanocomposites

2021 ◽  
pp. 002199832098875
Author(s):  
Danielle de Mattos Mariano ◽  
Daniela de França da Silva Freitas ◽  
Luis Claudio Mendes
Keyword(s):  
High Speed ◽  
Zirconium Phosphate ◽  
Melt Extrusion ◽  
Screw Speed ◽  
Crystallinity Degree ◽  
Metal Phosphates ◽  
Polymer Filler ◽  
Polypropylene Nanocomposites ◽  
The Time Domain ◽  
Induced Changes

Tetravalent metal phosphates find application mainly as a catalyst and ionic exchangers besides structural and some other properties. In this study, pristine zirconium phosphate (ZrP) and chemically modified with Jeffamine™ (variable amine:phosphate ratio) were used as fillers to yield polypropylene nanocomposites by melt extrusion. Additionally, two different screw speeds (60 and 120 rpm) were carried out. Structural, crystallographic, thermal, dynamic-mechanical, and relaxometry properties were assessed. The morphology was also noticed. Wide-angle X-ray diffraction revealed that high speed and chemical modified ZrP led to the mixing of intercalated and exfoliated microstructures. Screw speed (60 rpm) and zirconium phosphate promoted a slight increase of thermal stability. Crystallization temperature and crystallinity degree were strongly influenced by screw speed and zirconium phosphate. Hydrogen nuclear magnetic resonance in the time domain endorsed the existence of polymer/filler interaction. Both screw speed and zirconium phosphate induced changes in glass transition temperature and moduli (storage and loss). Scanning electron microscopy images corroborated the polymer/filler interaction due to the low level of micro void and filler detachment. Crystallographic, thermal, calorimetric, relaxometry and morphologic evaluations endorsed the better effect of high screw speed and good interaction between polypropylene and phosphate.

Nanocomposite of polypropylene/octadecylamine lamellar-zirconium phosphate: Influence of nanofiller and screw speed

2017 ◽  
Vol 52 (5) ◽  
pp. 701-711 ◽  
Author(s):  
Danielle M Mariano ◽  
Daniela FS Freitas ◽  
Luis C Mendes
Keyword(s):  
Thermal Stability ◽  
Zirconium Phosphate ◽  
Melt Processing ◽  
Screw Speed ◽  
Sem Images ◽  
Crystallinity Degree ◽  
Degradation Temperature ◽  
Diffraction Peaks ◽  
Melting And Crystallization Temperatures ◽  
Melting And Crystallization

Nanocomposite based on polypropylene and octadecylamine-modified lamellar-zirconium phosphate (PP/nano-ZrPOct) was prepared by melt processing. The action of the nanofiller and screw speed on the properties were evaluated. SEM images revealed that at highest screw speed, the higher nano-ZrPOct dispersion was achieved. In WAXD diffractrograms, some nanofiller diffraction peaks disappeared and a new peak was observed at low angle. There was evidence of increase of thermal stability although only discrete increasing in initial degradation temperature has been noticed. Melting and crystallization temperatures were invariable but crystallinity degree was influenced with a decreasing behavior at highest screw speed. The results strongly evidenced that the intercalation of the PP chains inside the nano-ZrPOct galleries and some degree of delamination of the nanofiller platelets have been achieved.

Secretagogue-induced changes in subcellular Ca2+ distribution in isolated pancreatic acini

1981 ◽  
Vol 240 (2) ◽  
pp. G130-G140
Author(s):  
R. L. Dormer ◽  
J. A. Williams
Keyword(s):  
Atomic Absorption Spectrometry ◽  
High Speed ◽  
Microsomal Fraction ◽  
Absorption Spectrometry ◽  
Subcellular Fractionation ◽  
Differential Centrifugation ◽  
Zymogen Granules ◽  
Pancreatic Acini ◽  
Induced Changes ◽  
Stimulation Of

In a prior study, we demonstrated that pancreatic secretagogues increased both the uptake into and washout of 45Ca2+ from isolated mouse pancreatic acini. The net result of these processes was an initial fall in total acinar cell Ca2+ content. In the present study, we have employed subcellular fractionation of acini under conditions that minimized posthomogenization redistribution of Ca2+ in order to localize those organelles involved in intracellular Ca2+ fluxes. Homogenization and differential centrifugation of acini, preloaded with 45Ca2+ and subjected to a period of washout, showed that carbachol induced an increased loss of 45Ca2+ from all fractions isolated. The high-speed microsomal fraction lost 45Ca2+ to a greater extent than did whole acini; measurement of total Ca2+ by atomic absorption spectrometry showed a net loss of Ca2+ from this fraction. Purification of the lower-speed fractions indicated that carbachol increased 45Ca2+ exchange with both zymogen granules and mitochondria, but net Ca2+ levels in these organelles were unchanged. It was concluded that stimulation of pancreatic acini by carbachol results in the release of calcium from a microsomal compartment leading to a rise in cytoplasmic Ca2+, increased exchange with granule and mitochondrial Ca2+, and increased efflux of Ca2+ from the cell.

Simultaneous Time-Frequency Control of Multi-Dimensional Micro-Milling Instability

2012 ◽  
Author(s):  
Meng-Kun Liu ◽  
Eric B. Halfmann ◽  
C. Steve Suh
Keyword(s):  
Frequency Response ◽  
High Speed ◽  
Frequency Control ◽  
External Perturbation ◽  
Micro Milling ◽  
Time Frequency ◽  
System A ◽  
Control Concept ◽  
The Time Domain ◽  
Tool Damage

A novel control concept is presented for the online control of a high-speed micro-milling model system in the time and frequency domains concurrently. Micro-milling response at high-speed is highly sensitive to machining condition and external perturbation, easily deteriorating from bifurcation to chaos. When losing stability, milling time response is no longer periodic and the frequency response becomes broadband, rendering aberrational tool chatter and probable tool damage. The controller effectively mitigates the nonlinear vibration of the tool in the time domain and at the same time confines the frequency response from expanding and becoming chaotically broadband. The simultaneous time-frequency control is achieved through manipulating wavelet coefficients, thus not limited by the increasing bandwidth of the chaotic system — a fundamental restraint that deprives contemporary controller designs of validity and effectiveness. The feedforward feature of the control concept prevents errors from re-entering the control loop and inadvertently perturbing the sensitive micro-milling system. Because neither closed-form nor linearization is required, the innate, genuine features of the micro-milling response are faithfully retained.

scholarly journals 15 Years MR-encephalography

2020 ◽  
Author(s):  
Juergen Hennig ◽  
Vesa Kiviniemi ◽  
Bruno Riemenschneider ◽  
Antonia Barghoorn ◽  
Burak Akin ◽  
...  
Keyword(s):  
Time Domain ◽  
High Speed ◽  
Direct Detection ◽  
Principal Component ◽  
Isotropic Resolution ◽  
High Acceleration Factor ◽  
Spiral Trajectory ◽  
Time Domain Data ◽  
High Acceleration ◽  
The Time Domain

Abstract Objective This review article gives an account of the development of the MR-encephalography (MREG) method, which started as a mere ‘Gedankenexperiment’ in 2005 and gradually developed into a method for ultrafast measurement of physiological activities in the brain. After going through different approaches covering k-space with radial, rosette, and concentric shell trajectories we have settled on a stack-of-spiral trajectory, which allows full brain coverage with (nominal) 3 mm isotropic resolution in 100 ms. The very high acceleration factor is facilitated by the near-isotropic k-space coverage, which allows high acceleration in all three spatial dimensions. Methods The methodological section covers the basic sequence design as well as recent advances in image reconstruction including the targeted reconstruction, which allows real-time feedback applications, and—most recently—the time-domain principal component reconstruction (tPCR), which applies a principal component analysis of the acquired time domain data as a sparsifying transformation to improve reconstruction speed as well as quality. Applications Although the BOLD-response is rather slow, the high speed acquisition of MREG allows separation of BOLD-effects from cardiac and breathing related pulsatility. The increased sensitivity enables direct detection of the dynamic variability of resting state networks as well as localization of single interictal events in epilepsy patients. A separate and highly intriguing application is aimed at the investigation of the glymphatic system by assessment of the spatiotemporal patterns of cardiac and breathing related pulsatility. Discussion MREG has been developed to push the speed limits of fMRI. Compared to multiband-EPI this allows considerably faster acquisition at the cost of reduced image quality and spatial resolution.

Analysis and Calculation of Electromagnetic Torque for the Voltage Source Traction Motors

2013 ◽  
Vol 446-447 ◽  
pp. 672-677
Author(s):  
Xiao Yu Wu ◽  
Zhe Ming Chen ◽  
Ze Hao Huang
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Voltage Source ◽  
Electromagnetic Torque ◽  
Motor Speed ◽  
Traction Motor ◽  
Traction Motors ◽  
Vehicle System ◽  
Mathematical Formulas ◽  
The Time Domain

The traction motor installed on the high-speed train is powered by inverter. A large number of harmonics may appear when motor is operating. Then the motor speed generate oscillation and finally the dynamic characteristic is affected in vehicle system. In this paper, relied on the electromagnetism of traction motor, the mechanism about emerging harmonic torque is analyzed. In addition, based on the equivalent circuit, the method of calculating the parameters in harmonic circuit is proposed. Two mathematical formulas are also proposed to obtain the fundamental electromagnetic torque and the harmonic electromagnetic torque on traction motor. The time domain and frequency domain distributions of the torques are gained and analyzed. Finally a calculation example of traction motor harmonic torque was analyzed and calculated, and prepared for further study of harmonic torque impacting on vehicle system dynamic performance.

Application of Wavelet De-Noising in Fault Diagnosis of Wind Turbine Gearboxes

2012 ◽  
Vol 562-564 ◽  
pp. 1091-1094 ◽  
Author(s):  
Hai Jiang Kou ◽  
Hui Qun Yuan ◽  
Xiao Yu Zhao
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Fault Location ◽  
Time Domain Analysis ◽  
Fault Detection And Diagnosis ◽  
Wind Turbine Gearbox ◽  
Stationary Noise ◽  
Wind Turbine System ◽  
Detection And Diagnosis ◽  
The Time Domain

Fault detection and diagnosis of a wind turbine gearbox are important to ensure the reliability and useful life of the wind turbine system. In this paper, an experimental test in wind turbine gearboxes is carried out to obtain faulted information which consists of response random non-stationary noise and the additional response due to failure. An approach, using wavelet de-noising method, is proposed for removing non-stationary noise from the recorded signals. The time domain analysis and frequency analysis are used to diagnose the fault location of the machine accurately. It is shown that wavelet de-noising method provides a better correction than conventional method in order to remove non-stationary noise. Diagnosis results indicate that the high-speed shaft of wind turbine gearboxes has a serious imbalance.

Efficient Techniques for the Computation of the Nonlinear Dynamics of a Foil-Air Bearing Rotor System

2013 ◽  
Author(s):  
Hai Pham ◽  
Philip Bonello
Keyword(s):  
Harmonic Balance ◽  
High Speed ◽  
Nonlinear Effects ◽  
Air Bearing ◽  
State Variables ◽  
Computational Burden ◽  
Rotor Systems ◽  
Symmetric Rotor ◽  
The Time Domain ◽  
Air Film

The foil-air bearing (FAB) plays a key role in the development of high speed, economical and environmentally friendly oil-free turbomachinery. However, FABs are known to be capable of introducing undesirable nonlinear effects into the dynamic response of a rotor-bearing system. This necessitates a means for calculating the nonlinear response of rotor systems with FABs. Up to now, the computational burden introduced by the interaction of the dynamics of the rotor, air film and foil structure has been overcome by uncoupling these three subsystems, introducing the potential for significant error. This paper performs the time domain solution of a simple rotordynamic system without uncoupling the state variables. This solution is then used as a reference for the verification of two proposed novel methods for reducing the computational burden: (a) use of harmonic balance; (b) use of Galerkin transformation. The applicability and accuracy of these two methods is illustrated on a simple symmetric rotor-FAB system.

scholarly journals Stability Analysis of Milling Process with Variable Spindle Speed and Pitch Angle considering Helix Angle and Process Phase Difference

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Gang Jin ◽  
Haotian Jiang ◽  
Jianxin Han ◽  
Zhanjie Li ◽  
Hua Li ◽  
...  
Keyword(s):  
Phase Difference ◽  
Pitch Angle ◽  
High Speed ◽  
Helix Angle ◽  
Stability Domain ◽  
Milling Process ◽  
Spindle Speed ◽  
The Stability ◽  
The Time Domain ◽  
Milling Chatter

Suppression of milling chatter by disrupting regenerative effect is a well-known method to obtain higher cutting stability domain. In this paper, a dynamic model of the milling process with variable spindle speed and pitch angle considering helix angle and process phase difference is presented. Then, an updated semidiscretization method is applied to obtain the stability chart. After the effectiveness of the proposed method is confirmed by comparisons with the previously published works and the time-domain simulations, lots of analyses are conducted to deeply evaluate the influence of the helix angle, the process phase difference, and feed per tooth on milling stability. Results show that the change of helix angle can result in significant stability discrepancies for both high-speed and low-speed regions. Though the process phase difference has the randomness and immeasurability in the practical application, it has an important influence on the stability and will result in a periodic evolution of the stability with a period π. Also, its recommended values are given for the practical milling process.

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