Biomedical subjects

Kama Huang

Publications and source records attributed to Kama Huang.

4 recordsLinked to original sources

PubMed2006

[Study on an optimized patch probe and its biomedical application].

A wide-band patch probe excited by coaxial line, which is useful for noninvasive measurement of superficial tissues at high frequencies, is presented in this paper. Optimization of the probe is performed by genetic algorithm (GA) combined with Finite Difference Time Domain (FDTD). Then the optimized round patch probe is used to measure reflection coefficient for 1-7 GHz. The measured results show some interesting phenomena, which are very useful for reconstruction of electric properties of superficial tissues.

Algorithms↗

PubMed2005

[Design and field calculation of coil array for transcranial magnetic stimulation (TMS) based on genetic algorithm].

It is the intent of this paper to locate the activation point in Transcranial Magnetic Stimulation (TMS) efficiently. The schemes of coil array in torus shape is presented to get the electromagnetic field distribution with ideal focusing capability. Then an improved adaptive genetic algorithm (AGA) is applied to the optimization of both value and phase of the current infused in each coil. Based on the calculated results of the optimized current configurations, ideal focusing capability is drawn as contour lines and 3-D mesh charts of magnitude of both magnetic and electric field within the calculation area. It is shown that the coil array has good capability to establish focused shape of electromagnetic distribution. In addition, it is also demonstrated that the coil array has the capability to focus on two or more targets simultaneously.

Algorithms↗

PubMed2005

[Bayesian representation of prior information and MCMC method in microwave imaging].

Microwave imaging for dielectric objects was considered in this paper. Applying Bayesian approach to represent prior information about permittivity distribution of observed object by prior probability density and combine measurements information of scattering field, we obtained posterior probability density that included synthetic information about the observed object. And then, Gibbs sampler, one of Markov Chain Monte Carlo method, was used to sample the posterior probability density. The sample mean was regarded as an evaluation of the permittivity distribution. The results of simulation imaging with "blocky" objects showed that this set of methods made good use of information and had the advantages of feasibility and very strong anti-noise ability. In addition,it is capable of describing (definite or indefinite) prior information in a convenient and controllable way, as well as capable of giving the "complete" solution, i.e., the occurrence probability of every permittivity distribution.

Bayes Theorem↗

PubMed2003

A hybrid numerical method to compute erythrocyte TMP in low-frequency electric fields.

This paper presents a coupling method of the finite element method and the boundary element method to compute the transmembrane potential (TMP) of an erythrocyte in a low-frequency electric field. We compute an in vitro erythrocyte's TMP induced by external electric fields by this hybrid method. It takes advantage of the homogeneous characteristics from both intracellular region and extracellular region. Moreover, we may use a fine three-dimensional (3-D) mesh around the thin membrane and avoid 3-D meshes in other regions. Numerical results of a spherical cell show that the hybrid method is accurate. The computed threshold of the applied electric field for membrane electric breakdown agrees well with those experimental results. Numerical results can also guide us to locate the maximum induced TMP on the erythrocyte membrane in various electric fields. Some further applications of the hybrid method are also discussed.

Algorithms↗