PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 11189270

[Unambiguous turbulence measurement method and system using transverse Doppler techniques].

J Li·M Wan·X Gong
View original source ↗Export metadata ↓

Abstract

This paper introduces the principle of Doppler ambiguity process and the ambiguity reduction techniques using dual-sample volume. An unambiguous fluid turbulence measurement method using transverse Doppler and dual-sample volume cross-correlation techniques is described. An experimental turbulence detection system is designed. Theoretical and experimental results show that this method can eliminate the Doppler ambiguity spectra produced by transit-time effect, turbulence and velocity gradient in sample volume.

Explore related subjects

Equipment DesignHemorheologyUltrasonography, DopplerEnglish AbstractJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J Li, M Wan, X Gong. 1997. [Unambiguous turbulence measurement method and system using transverse Doppler techniques].. https://pubmed.ncbi.nlm.nih.gov/11189270/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Dual-trap technique for reduction of low-frequency noise in force measuring optical tweezers.

High-resolution long-time force measurements by optical tweezers are often limited by low-frequency (1/f) noise. A dual-trap technique is presented that can reduce such noise in the force signal. It incorporates a second trap (a reference trap) that probes the noise in the system and it is based upon the assumption that the low-frequency parts of the noise from the two traps are correlated. A subtraction of the low-frequency signal from the reference trap from the signal from the force measuring trap will therefore yield a net signal that is significantly less influenced by noise. It is shown that this dual-trap technique can reduce the noise in the force signal up to 60% depending on detection bandwidth.

Equipment Design↗
PubMed2007

Optimization of doses received by the hospital staff and the members of the family of patients undergoing 111In-DTPA-D-Phe1-Octreotide therapy.

According to the Euratom Directives (96/29, 97/43), the doses received by the workers as well as the family of patients and third persons during medical exposures, should conform to the dose constraint levels (DCLs), established by the authorities for each group in the context of optimisation. This study deals with the implementation of a radiation protection protocol, concerning the aforementioned group members for patients undergoing treatment with 111In-DTPA-D-Phe1-Octreotide, after intra-arterial infusion. It is shown that by applying this protocol the annual doses to the medical and technical staff are considerably reduced and remain below the established DCLs. Following the post-release behaviour instructions given to the patient, doses to the family and third persons may be kept lower than the corresponding DCLs provided by the National Regulations.

Equipment Design↗
PubMed2007

In vivo myograph measurement of muscle contraction at optimal length.

BACKGROUND: Current devices for measuring muscle contraction in vivo have limited accuracy in establishing and re-establishing the optimum muscle length. They are variable in the reproducibility to determine the muscle contraction at this length, and often do not maintain precise conditions during the examination. Consequently, for clinical testing only semi-quantitative methods have been used. METHODS: We present a newly developed myograph, an accurate measuring device for muscle contraction, consisting of three elements. Firstly, an element for adjusting the axle of the device and the physiological axis of muscle contraction; secondly, an element to accurately position and reposition the extremity of the muscle; and thirdly, an element for the progressive pre-stretching and isometric locking of the target muscle. Thus it is possible to examine individual in vivo muscles in every pre-stretched, specified position, to maintain constant muscle-length conditions, and to accurately re-establish the conditions of the measurement process at later sessions. RESULTS: In a sequence of experiments the force of contraction of the muscle at differing stretching lengths were recorded and the forces determined. The optimum muscle length for maximal force of contraction was established. In a following sequence of experiments with smaller graduations around this optimal stretching length an increasingly accurate optimum muscle length for maximal force of contraction was determined. This optimum length was also accurately re-established at later sessions. CONCLUSION: We have introduced a new technical solution for valid, reproducible in vivo force measurements on every possible point of the stretching curve. Thus it should be possible to study the muscle contraction in vivo to the same level of accuracy as is achieved in tests with in vitro organ preparations.

Equipment Design↗