A Novel Method to Improve Dynamic Performance of GPS Carrier Tracking Loop with INS Aiding

2014 ◽  
Author(s):  
Chun-Hua Ren ◽  
Qin-Qin Liu ◽  
Man-Xi Wang ◽  
Li-Ping Yang
Keyword(s):  
Dynamic Performance ◽  
Tracking Loop ◽  
Novel Method ◽  
Ins Aiding

Parameter Optimization of Virtual Impedance for Parallel Inverter

2014 ◽  
Vol 986-987 ◽  
pp. 1973-1976
Author(s):  
Ping Wang ◽  
Liu Yang
Keyword(s):  
Parameter Optimization ◽  
Dynamic Performance ◽  
Design Methods ◽  
New Method ◽  
Conventional Design ◽  
Equivalent Impedance ◽  
Novel Method ◽  
Virtual Impedance ◽  
Frequency Curves ◽  
Parallel Inverter

This paper deals with parameter optimization of virtual impedance of parallel inverter. Conventional design methods determine parameters by observing the changes of amplitude-frequency and phase frequency curves of the equivalent impedance. However, those methods always neglect the dynamic performance of inverters in parallel. This paper proposes a novel method to optimize the coefficients of virtual impedance and experiments show that new method improves the dynamic performance of parallel inverter effectively, as well as stability and flexibility.

Dynamic Performance of the Bearing-Rotor System in the Ultra-High Speed Electric Spindle with a Additional Supporting System Make up of the Permanent Magnetic Bearings

2011 ◽  
Vol 295-297 ◽  
pp. 2294-2299
Author(s):  
Song Sheng Li ◽  
Hua Wei Mao ◽  
Ping Chen ◽  
Xiao Huang ◽  
Peng Zhou ◽  
...  
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Permanent Magnets ◽  
Dynamic Performance ◽  
Rotor System ◽  
Magnetic Bearings ◽  
Supporting System ◽  
Ultra High Speed ◽  
Novel Method ◽  
Additional Support

A novel method, aiming at solving the problem that the ultra-high-speed electric spindle tends to vibrate as its stiffness is small, using the repulsion of permanent magnets based on the theory that repulsion increased while the two magnets come close, is provided in this paper to design a electric spindle within additional support bearing system consist of two radial permanent magnet rings against each other. This paper also analyses the dynamic performance of radial permanent magnet bearings additional supporting system for ultra-high speed electric rotor system, result shows that the radial permanent magnetic bearings additional supporting system designed for improving the critical speed of the rotor system, reducing the rotor radial dynamic response, can effectively improve the dynamic performance and operational stability of ultra-high speed electric spindle rotor system.

A Novel, Efficient, Unit Circle-Based, Method for Positioning and Operating Cryo-Surgical Probes in Convex Target Areas

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Zaur Magalov ◽  
Shitzer Avraham ◽  
Degani David
Keyword(s):  
Unit Circle ◽  
Dynamic Performance ◽  
Radius Of Curvature ◽  
Target Area ◽  
Lethal Temperature ◽  
Single Probe ◽  
Novel Method ◽  
Specific Distance ◽  
Predetermined Number

Abstract A novel method for positioning and operating needle-like cryo-surgical probes in 2D convex target areas is presented. The method is based on the recorded dynamic performance of a single probe, termed “unit circle,” (UC) embedded in a semi-infinite, tissue-like medium. Up to 15 cryo-probes, inserted into the same depth, are operated uniformly for 2–5 min. A predetermined number of probes are rearranged inside the target area until a “tight configuration” is obtained. The probes are initially arranged inside the target area such that the “lethal temperature” circles produced by them are tangent to its contour and to both adjacent lethal temperature circles. Subsequently, all probes are repositioned inwardly, each at a specific distance that depends on the local radius of curvature of the target area. Resulting total “defect areas”—internal and external—for a number of demonstrated cases, amounted to between 2.5% and 7.6% of the target area. The lower values of the defect areas were obtained with increasing numbers of inserted probes coupled with shorter operating times. Possible freezing damages to regions beyond the target area were reduced by up to about 30% for these cases. Similar results were obtained for a case of combined convex-concave target area, treated with additional, externally inserted, heating probes.

On the improvement of the dynamic performance of dielectric elastomer actuators for active compression

2018 ◽  
Vol 29 (5) ◽  
pp. 986-997 ◽  
Author(s):  
Hamza Edher ◽  
Armaghan Salehian
Keyword(s):  
Dynamic Performance ◽  
Hold Time ◽  
Compressive Force ◽  
Dielectric Elastomer ◽  
Output Curve ◽  
Dielectric Elastomer Actuator ◽  
Dielectric Elastomer Actuators ◽  
Low Weight ◽  
Output Force ◽  
Novel Method

Dielectric elastomer actuators have been considered for an increasing number of applications due to their desirable characteristics of low weight, high strain outputs and favourable material costs. The present work describes the use of a dielectric elastomer actuator in conjunction with a belt mechanism to apply cyclic active compression. The belt mechanism helps convert the stress relaxation upon the voltage application to the dielectric elastomer actuator to a compressive force. Testing is conducted using multi-layered silicone–based dielectric elastomer actuators. A novel method of dynamically charging dielectric elastomer actuators through manipulating the input signal shape, termed the hold method, is introduced. Using this method, cyclic actuation strain output can be increased by 24% with insignificant change in actuation output curve shape. Furthermore, the effect of pre-stretch ratios on the output force amplitudes is characterized. The optimized hold time parameters obtained through cyclic dielectric elastomer force and strain are utilized for active compression physiological testing and a pressure gradient of 10 mmHg is achieved.

A novel method to design tolerance of aero-engine casing by integrating 3-D assembly tolerance with performance instability

2021 ◽  
pp. 095440542110609
Author(s):  
Hehe Kang ◽  
Zhi-Min Li ◽  
Tao Liu ◽  
Wei Yuan ◽  
Yuping Wu
Keyword(s):  
Natural Frequency ◽  
Dynamic Performance ◽  
Tolerance Analysis ◽  
Frequency Distributions ◽  
Assembly Tolerance ◽  
Aero Engine ◽  
Novel Method ◽  
Tolerance Model ◽  
Assembly Deviation ◽  
The Given

Assembly quality of aero-engine casing plays a key role in the whole aero-engine, since it is directly related to the final function and dynamic performance. However, during the design phase, the tolerance analysis is usually conducted independently without any consideration of the effect on the dynamic characteristic. This paper aims to integrate manufacturing precision with dynamic performance instability together. First, the 3-D tolerance model of the aero-engine casing is constructed based on the Jacobian-Torsor theory. The target deviation from the tolerance model is defined as the input variable into the vibratory governing equation. Then, the effect of 3-D assembly deviation on the natural frequency is studied. The corresponding frequency distributions for different vibration modes are illustrated. Finally, the mapping relationship between assembly tolerance and fluctuation ratio of natural frequency is established through the 3-D fitted surface. Under the given constraint of performance stability, the optimized tolerance zone is obtained. This work provides a significant guidance for performance improvement and tolerance design in the aero-engine casing assembly.

scholarly journals Design and Validation of a Cascading Vector Tracking Loop in High Dynamic Environments

2021 ◽  
Vol 13 (10) ◽  
pp. 2000
Author(s):  
Zhiyong Tu ◽  
Yidong Lou ◽  
Wenfei Guo ◽  
Weiwei Song ◽  
Yusheng Wang
Keyword(s):  
Unscented Kalman Filter ◽  
Negative Impact ◽  
Dynamic Performance ◽  
Phase Error ◽  
Tracking Error ◽  
Doppler Frequency ◽  
Convergence Time ◽  
Tracking Loop ◽  
Vector Tracking ◽  
High Dynamic

This paper designs a cascading vector tracking loop based on the Unscented Kalman Filter (UKF) for high dynamic environment. Constant improvement in dynamic performance is an enormous challenge to the traditional receiver. Due to the doppler effect, the satellite signals received by these vehicles contain fast changing doppler frequency shifts and the first and second derivatives of doppler frequency, which will directly cause a negative impact on the receiver’s stable tracking of the signals. In order to guarantee the dynamic performance and the tracking accuracy, this paper designs a vector carrier structure to estimate the doppler component of a signal. Firstly, after the coherence integral, the IQ values are reorganized into new observations. Secondly, the phase error and frequency of the carrier are estimated through the pre-filter. Then, the pseudorange and carrier frequency are used as the observations of the main filter to estimate the motion state of the aircraft. Finally, the current state is fed back to the carrier Numerical Controlled Oscillator (NCO) as a complete closed loop. In the whole structure, the cascading vector loop replaces the original carrier tracking loop, and the stable signal tracking of code loop is guaranteed by carrier assisted pseudo-code method. In this paper, with the high dynamic signals generated by the GNSS signal simulator, this designed algorithm is validated by a software receiver. The results show that this loop has a wider dynamic tracking range and lower tracking error than the second-order frequency locked loop assisted third-order phase locked loop in high dynamic circumstances. When the acceleration of carrier is 100 g, the convergence time of vector structure is about 100 ms, and the carrier phase error is lower than 0.6 mm.

The removal and morphology of intact biofilms from implanted venous access devices

1995 ◽  
Vol 53 ◽  
pp. 1020-1021
Author(s):  
M.A. Gregory ◽  
G.P. Hadley
Keyword(s):  
Patient Selection ◽  
Surgical Oncology ◽  
Venous Access ◽  
Common Procedure ◽  
Indwelling Catheters ◽  
Careful Patient ◽  
Novel Method ◽  
The Subject ◽  
Vascular Catheters ◽  
Venous Access Devices

The insertion of implanted venous access systems for children undergoing prolonged courses of chemotherapy has become a common procedure in pediatric surgical oncology. While not permanently implanted, the devices are expected to remain functional until cure of the primary disease is assured. Despite careful patient selection and standardised insertion and access techniques, some devices fail. The most commonly encountered problems are colonisation of the device with bacteria and catheter occlusion. Both of these difficulties relate to the development of a biofilm within the port and catheter. The morphology and evolution of biofilms in indwelling vascular catheters is the subject of ongoing investigation. To date, however, such investigations have been confined to the examination of fragments of biofilm scraped or sonicated from sections of catheter. This report describes a novel method for the extraction of intact biofilms from indwelling catheters.15 children with Wilm’s tumour and who had received venous implants were studied. Catheters were removed because of infection (n=6) or electively at the end of chemotherapy.

Sign in / Sign up

Export Citation Format

Share Document