Influence enhancement effect of bi-frequency ultrasonic irradiation by TA fluorescence method

Based on a previous research of cavitation effect under bi-frequency ultrasound irradiation, this paper studies bi-frequency irradiations with similar experimental settings. The additional irradiation sources with frequencies of 1.04MHz, 0.8MHz and 1.7MHz are individually combined with the main ultrasonic irradiation source with frequency of 28kHz to form bi-frequency ultrasonic irradiation. The intensity of 28kHz irradiation was fixed at 12.5W/cm^2, while the intensity of the ultrasound at the other three frequencies is varied from1 W/cm^2 to 18 W/cm^2. It turns out that under the influence of the bi-frequency irradiation, the fluorescence intensity is obviously greater than the sum of those at individual frequencies. So the frequency of the additional sonication strikingly influences the fluorescence enhancement effect. For example, the fluorescence enhancement effect of 1.04MHz is stronger than that of 1.7MHz, and the enhancement effect of 0.8MHz is further stronger than that of 1.04MHz. Under the sonic intensity of (7.9)W/cm^2, the fluorescence intensity of 1.04MHz is approximately twice that of 1.7MHz while the fluorescence intensity of 0.8MHz is approximately 1.5 times that of 1.04MHz.

A New Bi-Frequency Soil Smart Sensing Moisture and Salinity for Connected Sustainable Agriculture

Optimizing water consumption is a major challenge for more sustainable agriculture with respect for the environment. By combining micro and nanotechnologies with the offered solutions of IoT connection (Sigfox and LoRa), new sensors allow the farmer to be connected to his agricultural production by mastering in real time the right contribution needed in water and fertilizer. The sensor designed in this research allows a double measurement of soil moisture and salinity. In order to minimize the destructuring of the ground to insert the sensor, we have designed a cylindrical sensor, easy to insert, with its electronics inside its body to propose a low power electronic architecture capable of measuring and communicating wireless with a LoRa or Sigfox network or even the farmer’s cell phone. This new smart sensor is then compared to the current leaders in agriculture to validate its performance. Finally, the sensor has better performance than commercials, a better response time, a better precision and it will be cheaper. For the salinity measure, it can detect the level of fertilizer in the soil according to the need of farmers.

Acousto-optic modulator-based bi-frequency interferometer for quantum technology

We demonstrate a high-performance acousto-optic modulator-based bi-frequency interferometer,which can realize either beating or beating free interference for a single-photon level quantum state.Visibility and optical efficiency of the interferometer are(99.5±0.2)%and(95±1)%,respectively.The phase of the interferometer is actively stabilized by using a dithering phase-locking scheme,where the phase dithering is realized by directly driving the acousto-optic modulators with a specially designed electronic signal.We further demonstrate applications of the interferometer in quantum technology,including bi-frequency coherent combination,frequency tuning,and optical switching.These results show the interferometer is a versatile device for multiple quantum technologies.

Study on the description method of upper limb's muscle force levels during simulated in-orbit operations

The dexterous upper limb serves as the most important tool for astronauts to implement in-orbit experiments and operations. This study developed a simulated weightlessness experiment and invented new measuring equipment to quantitatively evaluate the muscle ability of the upper limb. Isometric maximum voluntary contractions （MVCs） and surface electromyography （sEMG） signals of right-handed pushing at the three positions were measured for eleven subjects. In order to enhance the com- prehensiveness and accuracy of muscle force assessment, the study focused on signal processing techniques. We applied a combination method, which consists of time-, frequency-, and bi-frequency- domain analyses. Time- and frequency-domain analyses estimated the root mean square （RMS） and median frequency （MDF） of sEMG signals, respectively. Higher order spectra （HOS） of bi-frequency domain evaluated the maximum bispectrum amplitude （Bmax）, Gaussianity level （Sg） and lineari- ty level （S0 of sEMG signals. Results showed that B S,, and RMS values all increased as force increased. MDF and Sg val- ues both declined as force increased. The research demonstrated that the combination method is superior to the conventional time- and frequency-domain analyses. The method not only described sEMG signal amplitude and power spectrum, but also deeper characterized phase coupling information and non-Gaussianity and non-linearity levels of sEMG, compared to two conventional analyses. The finding from the study can aid ergonomist to estimate astronaut muscle performance, so as to opti- mize in-orbit operation efficacy and minimize musculoskeletal injuries.