Development of Wireless Technique to Regulate Seed Dropping in a Seeder for Intercropping

Although intercropping gives additional yield per unit area than sole cropping, yield may also decrease as the crops differ in their competitive abilities. To avoid competition and to accompany complimentary action between the base crop and inter crop in intercropping practise, proper crop ratio of two crops should be maintained. When sowing with available seeders crop ratio was not maintained because of non-availability of a seed hopper, handling two different varieties of seeds and the un controlled seed flow from the hopper to the seed tube when ground wheel is rotating. To look after this problem an experiment was conducted at DFMPE, AEC & RI, Tamil Nadu Agricultural University, Kumulur by fabricating a seed hopper consisting of two compartments and circular shaped outlet for two variety of seeds and developing an RF (radio frequency) wireless technology to control servo motor in order to restrict the seed drop from seed hopper to the seed tube even though ground wheel is in running condition. In this paper considering a seven-row seeder, the performance of a micro controller coded with appropriate programme in embedded C language which can regulate seven servo motors each at seven seed hoppers, functioning of RF transmitter sketch, functioning of RF receiver sketch, header issue & its solution, angle conversion of servo shaft and power consumption was observed and discussed. Total power required for operating RF electronic setup containing seven servomotors was recorded as 5 V 12 A. The angle of rotation of servo motor shaft was from 0º to 165º when pulse width range in micro controller was set from 0 and 2400 micro seconds. The servo did not respond in the hardware interfacing because both the libraries use timer 1 interrupt which created an error issue. In order to overcome that “Servo timer 2.h” header was issued instead of servo.h. Then sketch was compiled and was executed successfully.

A Cascaded MEMS Amplitude Demodulator for Large Dynamic Range Application in RF Receiver

An amplitude demodulator with a large dynamic range, based on microelectromechanical systems (MEMS), is proposed in this paper. It is implemented as a cascade of a capacitive and a thermoelectric sensor. Two types of the transducer can improve the measurement range and enhance the overload capacity. This MEMS-based demodulation is realized by utilizing the square law relationship and the low-pass characteristic during the electromechanical and thermoelectric conversion. The fabrication of this device is compatible with the GaAs monolithic microwave integrated circuit (MMIC) process. Experiments show that this MEMS demodulator can realize the direct demodulation of an amplitude modulation (AM) signal with a carrier frequency of 0.35–10 GHz, and cover the power range from 0 to 23 dBm. This MEMS demodulator has the advantages of high power handling capability and zero DC power consumption.

CT radiomics for predicting PD-L1 expression on tumor cells in gastric cancer

Purpose To explore CT radiomics for predicting programmed cell death ligand 1 on tumor cells (PD-L1) status in gastric cancer (GC).Methods From March 2019 to July 2020, 358 patients identified with GC who underwent surgery at our hospital were enrolled in this study retrospectively. All patients were divided into primary (n=239) and validation (n=119) cohorts based on the time of surgery at a ratio of 3:1. Radiomic features were extracted from regions of interest manually drawn on venous CT images. Besides, preoperative tumor markers of all patients were collected and analyzed. The signatures based on radiomics were built using Support Vector Machine (SVM) and Random Forest (RF). Receiver operating characteristic (ROC) curve was performed to assess diagnostic efficiency. Decision curve analysis confirmed the clinical utility.Results Numerous radiomic features (all p<0.05) differed significantly between GCs with different PD-L1 status. The model developed by SVM algorithm in the primary and validation cohort achieved better performance with AUCs of 0.704 and 0.799, respectively.Conclusion It was promising to predict PD-L1 status in GCs noninvasively using CT radiomics. It might help to improve clinical decision making with regard to immunotherapy.

A CMOS RF Receiver with Improved Resilience to OFDM-Induced Second-Order Intermodulation Distortion for MedRadio Biomedical Devices and Sensors

A MedRadio RF receiver integrated circuit for implanted and wearable biomedical devices must be resilient to the out-of-band (OOB) orthogonal frequency division modulation (OFDM) blocker. As the OFDM is widely adopted for various broadcasting and communication systems in the ultra-high frequency (UHF) band, the selectivity performance of the MedRadio RF receiver can severely deteriorate by the second-order intermodulation (IM2) distortion induced by the OOB OFDM blocker. An analytical investigation shows how the OFDM-induced IM2 distortion power can be translated to an equivalent two-tone-induced IM2 distortion power. It makes the OFDM-induced IM2 analysis and characterization process for a MedRadio RF receiver much simpler and more straightforward. A MedRadio RF receiver integrated circuit with a significantly improved resilience to the OOB IM2 distortion is designed in 65 nm complementary metal-oxide-semiconductor (CMOS). The designed RF receiver is based on low-IF architecture, comprising a low-noise amplifier, single-to-differential transconductance stage, quadrature passive mixer, trans-impedance amplifier (TIA), image-rejecting complex bandpass filter, and fractional phase-locked loop synthesizer. We describe design techniques for the IM2 calibration through the gate bias tuning at the mixer, and the dc offset calibration that overcomes the conflict with the preceding IM2 calibration through the body bias tuning at the TIA. Measured results show that the OOB carrier-to-interference ratio (CIR) performance is significantly improved by 4–11 dB through the proposed IM2 calibration. The measured maximum tolerable CIR is found to be between −40.2 and −71.2 dBc for the two-tone blocker condition and between −70 and −77 dBc for the single-tone blocker condition. The analytical and experimental results of this work will be essential to improve the selectivity performance of a MedRadio RF receiver against the OOB OFDM-blocker-induced IM2 distortion and, thus, improve the robustness of the biomedical devices in harsh wireless environments in the MedRadio and UHF bands.