Highly Sensitive Quartz-Based Sensing System for the Detection of Subpercentage Changes in the Relative Permittivity of Liquids Flowing in Microchannels

We describe a highly sensitive quartz sensor for measuring changes in the relative permittivity of liquids flowing in microchannels. The proposed method uses a highly stable oscillator and capacitance-dependent quartz crystal together with a capacitance-sensitive element attached along the microchannel. A change in the relative permittivity of the fluid induces a change in the capacitance of the sensitive element in the aF range, which is detected as a change in the resonant frequency. The advantages of the proposed measurement technique are the extreme sensitivity (changes in the relative permittivity as low as 0.01% can be detected), the temperature independence of the setup between 10 and 40 °C, the stability (the frequency reading fluctuates within 0.025 Hz), and the low cost compared with the methods that use impedance analyzers or lock-in amplifiers. We present the use of the method to detect changes in mixtures of liquids if the temperature, volume fractions, or properties of one liquid change. The method presents a useful tool for applications in biology, chemistry, pharmacy, and technology in general wherever accurate monitoring of compositions of fluids is required and where changes, for example, due to temperature variation or mixture aging, need to be detected in real time.

The Technology Head Characteristic Frequency Reading and Research on Technology and Material Parametres Influence on AWJ Technology Manufacturing Systems Technology Head Reverberance

The paper describes a vibrations acceleration signals scanning and processing principle at technology head characteristic frequency reading during AWJ manufacturing process.

A Study of the Frequency Reading Fundamental Vocal of Young Black Adults

This study investigated the measures of central tendency (mean mode) and dispersion (standard deviations and ranges) of the reading fundamental vocal frequency in young black adults. The subjects were 200 (100 males/100 females college student volunteers whose ages ranged from 18 to 29 years, A fundamental frequency analyzer (FLORIDA I) was used to measure the fundamental vocal frequency. The mean modal fundamental vocal frequency for males was 110.15 Hz, with a mean range from 81.95 Hz to 158.50 Hz. The mean modal fundamental vocal frequency for females was 193.10 Hz, with a mean range from 139,05 Hz to 266.10 Hz, The males showed a slightly greater range expressed in tones than did the females, Compared to a similar white population studied by Fitch & Holbrook (1970), the black population had lower mean modal fundamental vocal frequencies and greater mean frequency ranges, Fitch's white subjects showed a greater range below the mean mode than above it. This behavior was reversed for the black subjects of the present study. Such patterns of vocal behavior may be important clues which alert the listener to the speaker's racial identity.

Some Effects of Noise on the Speaking Behavior of Stutterers

The purpose of the present research was to determine the influence of the loudness and spectrum of noise stimuli on stuttering frequency, reading rate, and vocal level. During each of six noise conditions and one non-noise condition, nine stutterers continuously read aloud prose passages during four successive five-minute periods. Low-pass (500-Hz cutoff frequency), high-pass (500-Hz cutoff frequency), and broad-band noise, psychophysically equated for loudness at two different levels, was presented during the third period of the six noise conditions. Stuttering frequency, reading rate, and vocal level were measured for the second and third periods of all conditions. The stutterers increased their vocal level while decreasing their stuttering frequency as a result of the loudness rather than the frequency spectrum of the noise. Reading rate was not significantly influenced by changes in the loudness or frequency spectrum of the noise. These results do not support the findings of others that low-pass noise decreases stuttering more than does high-pass noise.