PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 1587107

Electrical impedance tomography. Electrode current determination from programmable voltage sources.

F J Lidgey·Q S Zhu·C N McLeod·W R Breckon
View original source ↗Export metadata ↓

Abstract

The accuracy requirements for adaptive current electrical impedance tomography (EIT) measurements exceed the capability of available current sources. A new architecture for an EIT system is described in which the electrode current is set indirectly from a voltage-drive structure. A numerically inverted admittance matrix, obtained from current measurements and driving voltages, has been used to achieve the desired current pattern from programmable voltage sources.

Explore related subjects

Electric ConductivityHumansTomographyJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

F J Lidgey, Q S Zhu, C N McLeod, W R Breckon. 1992. Electrical impedance tomography. Electrode current determination from programmable voltage sources.. https://doi.org/10.1088/0143-0815%2F13%2Fa%2F009

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

KEEP EXPLORING

Related citations

PubMed2007

Conductance-controlled point functionalization of single-walled carbon nanotubes.

We used covalent attachments to single-walled carbon nanotubes (SWNTs) to fabricate single-molecule electronic devices. The technique does not rely on submicrometer lithography or precision mechanical manipulation, but instead uses circuit conductance to monitor and control covalent attachment to an electrically connected SWNT. Discrete changes in the circuit conductance revealed chemical processes happening in real time and allowed the SWNT sidewalls to be deterministically broken, reformed, and conjugated to target species. By controlling the chemistry through electronically controlled electrochemical potentials, we were able to achieve single chemical attachments. We routinely functionalized pristine, defect-free SWNTs at one, two, or more sites and demonstrated three-terminal devices in which a single attachment controls the electronic response.

Electric Conductivity↗
PubMed2007

A model explaining genotypic and ontogenetic variation of leaf photosynthetic rate in rice (Oryza sativa) based on leaf nitrogen content and stomatal conductance.

BACKGROUNDS AND AIMS: Identification of physiological traits associated with leaf photosynthetic rate (Pn) is important for improving potential productivity of rice (Oryza sativa). The objectives of this study were to develop a model which can explain genotypic variation and ontogenetic change of Pn in rice under optimal conditions as a function of leaf nitrogen content per unit area (N) and stomatal conductance (g(s)), and to quantify the effects of interaction between N and g(s) on the variation of Pn. METHODS: Pn, N and g(s) were measured at different developmental stages for the topmost fully expanded leaves in ten rice genotypes with diverse backgrounds grown in pots (2002) and in the field (2001 and 2002). A model of Pn that accounts for carboxylation and CO diffusion processes, and assumes that the ratio of internal conductance to g(s) is constant, was constructed, and its goodness of fit was examined. KEY RESULTS: Considerable genotypic differences in Pn were evident for rice throughout development in both the pot and field experiments. The genotypic variation of Pn was correlated with that of g(s) at a given stage, and the change of Pn with plant development was closely related to the change of N. The variation of g(s) among genotypes was independent of that of N. The model explained well the variation in Pn of the ten genotypes grown under different conditions at different developmental stages. Conclusions The response of Pn to increased N differs with g(s), and the increase in Pn of genotypes with low g(s) is smaller than that of genotypes with high g(s). Therefore, simultaneous improvements of these two traits are essential for an effective breeding of rice genotypes with increased Pn.

Electric Conductivity↗