Shizuo Mizushina

Retrieval of Temperature-Depth Profiles in Biological Objects from Multi-Frequency Microwave Radiometric Data

A method of retrieving a temperature-depth profile in biological object from a set of multi-frequency microwave radiometric data has been developed. The method is a combination of model-fitting and Monte Carlo techniques and is capable of estimating a profile and its confidence interval as a function of the depth. We use 2σ -intervals as a measure of the precision of tissue temperature measurements. The method was tested and supported by an experiment in which temperature distributions in a muscle equivalent agar phantom were measured using a 5-band, 1-3.8 GHz radiometer with the brightness temperature resolution of 0.05-0.07 K. A typical result of the experiment showed that 2σ -intervals were 1 K or less for 0 < z < 3 cm, 1.4 K at z = 4 cm, and 3 K at z = 5 cm. A numerical simulation study was made using this technique to assess effects of the selection of measurement frequencies, number of frequency bands, brightness temperature resolution of radiometer and thickness of fat layer on the precision. Resul...

A fuzzy approach to the rate control in an artificial cardiac pacemaker regulated by respiratory rate and temperature: A preliminary report

Fuzzy theory was applied to the rate control of a cardiac pacemaker which uses two parameters, respiratory rate and temperature, as the parameters for rate regulation. Using 25 fuzzy reasoning rules derived from five mongrel dogs, the pacing rates in three animals were calculated and compared with the intrinsic heart rates. It is concluded that the fuzzy method is well suited for the rate determination of a multi-parameter rate-responsive cardiac pacemaker.

A Three-Band Microwave Radiometer System for Noninvasive Measurement of the Temperature at Various Depths

An experimental three-band (1.5,2.5,3.5+-0.5GHz) radiometer system and a data analysis procedure have been developed for noninvasive measurement of the temperature at various depths in a biological body. Using them, we made temperature measurement experiments on the abdominal region of rabbits. The results of the experiments demonstrate the feasibility of the multifrequency radiometry for this purpose.

A method of solution for a class of inverse problems involving measurement errors and its application to medical microwave radiometry

Retrieval of temperature-vs.-depth profiles in a biological tissue structure from multifrequency microwave radiometric measurement data constitutes a typical inverse problem in which the data involve relatively large measurement errors. The authors have developed a method of solution for a class of problems of this type. The method gives solutions in terms of the confidence interval and level. It also has a built-in capability of assessing the degree of fit of solutions to unknown actual source distributions. An agar phantom experiment and computer simulation based on a five-band (1-4-GHz) radiometry were performed to test the method, and the results are presented.<<ETX>>

Cardiac pacemaker regulated by respiratory rate and blood temperature.

A new method using respiratory rate and temperature as the guides for optimal pacing is proposed. A pacemaker was fabricated which senses these two parameters simultaneously. The pacemaker functions by calculating the cardiac rate, which would he derived from the respiratory rate and the blood temperature. The higher of the two rates is adopted as the cardiac pacing rate, i.e., at which stimuli will be delivered. The operation was tested in a mongrel dog with complete atrioventricular block. After the induction of anesthesia, a thermistor temperature probe was inserted into right atrium and a respiratory rate sensor was attached around the chest. After administration of a pyrogenic drug, both respiratory rate and blood temperature increased. The pacing rate was increased from 178 beats/minute(bpm) at 36.4°C. blood temperature, and 26.5 acts/minute(apm), respiratory rate, to 233 bpm at 40.1°C and 40.0 apm. Cardiac output was increased from 2.25 liters/minute(1/pm) at the beginning to 2.50 l/pm at maximum. The transition of the guide from respiratory rate to temperature was observed at about 38°C.

A Three-Band Microwave Radiometer for Noninvasive Temperature Measurement

A three-band radiometer operating at 1.5, 2.5 and 3.5 GHz with a 1-GHz band-width has been developed for noninvasive measurement of body temperature. An experiment using a water-bath filled with tap water showed that the instrument could measure the temperature (15 °C) of a subjacent layer (depth > 2 cm), differentiating it from that (22 °C) of the surface layer (depth < 2 cm).

Theoretical Analysis of a Ridged-Waveguide Mounting Structure

The driving-point impedance of a single-gap thin conductor strip, a model of the ribbon-and-pedestal of device package, mounted across the gap of a ridged waveguide has been derived using the induced EMF method. The dyadic Greens function for the ridged waveguide was derived to facilitate the analysis. An equivalent circuit was developed which involved an infinite array of transformers representing the couplings between the conductor strip and the waveguide normal modes. Numerical results for a typical example were also given, demonstrating a remarkably smooth behavior of the driving-point impedance of the mount over a frequency range from 5.4 GHz to 25.4 GHz.

A WIRELESS SYSTEM FOR DISASTER DAMAGE MONITORING IN VULNERABLE ISM BAND

A wireless communication system, especially a wireless LAN (W-LAN) which operates in the ISM (Industrial, Scientific and Medical) band, may be widely used in a home network to transmit data of mobile computing, entertainments, security information, and/or state information of home. The W-LAN system is also prevailing not only in a home or an office, but also in outdoor environments in these days. A TD-CDMA system, which we have developed to collect damage assessment information for a natural disaster, operates in a shared frequency band, 2.4GHz ISM band. This paper describes an influence of the W-LAN on the experimental system, and discusses an interference mitigation method. The experiments show the interference of W-LAN deteriorates the frame error rate (FER) on the order of 10. The proposed mitigation method improves SINR with a closed-loop power control technique of CDMA. The results of the experiments show that the FER recovers at 1×10 or less using the proposed mitigation method, and that the monitoring system is satisfactorily feasible to operate in the vulnerable ISM band.

Microcomputer-based cardiac pacemaker-control system through blood temperature

A microcomputer-based temperature-sensitive cardiac pacemaker system and some preliminary experiments are described. The system consists of a microcomputer, a twin 5 in floppy disk unit, expansion and interface units, a visual display unit and a printer. It senses the blood temperature in the right atrium, determines the pacing rate and supplies the heart with stimulating pulses. System-heart interfacing is performed by the separate pacing and sensing units which communicate with the computer via a peripheral interface IC in an expansion unit. The pacing rate is determined by software, rather than a combination of hardware elements. The temperature response time of the system, from 25 degrees C to 40 degrees C is about 26 s, and this would seem to be satisfactory given that smaller and slower changes in blood temperature are normal.

A technique for wireless LAN connection through building concrete wall at 2.4GHz

A technique for wireless LAN connection through building concrete wall is proposed. The propagation loss in a 10cm-thick concrete is found at about −8.9dB at 2.4GHz by simulation and experiment. Using a large aperture horn antenna mounted flush on the back of wall, the attenuated signal power is raked over a wide area and reradiated into a space behind the wall via a small second antenna connected back-to-back to the first one in the downlink. It is possible to make the reradiated field in a limited region near the second antenna nearly as strong as that of the wave incident on the wall. An unlicensed small-power relay station based on the IEEE802.11g/b standards is placed in this region to complete the downlink. In the uplink, the signal power from the relay station antenna is picked up by the second antenna and radiated into the space outside the wall. An amplifier of about 13dB gain is required in the uplink in order to make the uplink versus downlink link budgets balanced. The amplifier gain is so set as to comply with the limit set by regulatory agency. The proposed method is analyzed by 3D simulation and its feasibility is supported by experiment.