The tri-band high spectral resolution spectrometer with gratings in tandem for the charge-exchange recombination spectroscopy diagnostic system on HL-2A tokamak

Charge-exchange(CX) recombination spectroscopy is a powerful tool monitoring ion temperature and plasma rotation with good temporal and spatial resolutions. A compact, new design for a high-throughput, tri-band high spectral resolution spectrometer has been developed for the charge-exchange recombination spectroscopy measurement on the HL-2A tokamak. The simultaneous measurements of He II(468.57 nm), C VI(529.1 nm), and Dα(656.1 nm accompanied by beam emission spectra) with an acquisition frequency up to 400 Hz are achieved by vertically binning the spectrum from each fiber in experiments. Initial results indicate that the system can provide radial profiles of not only ion temperature and rotation velocity,but also concentration of carbon. For the case of helium, the measurements for the ion temperature and rotation velocity are straightforward but the apparent concentration associated with the observed CX intensity is obviously too high. Modeling of the active He II CX feature including plume contributions needs to be carried out to extract the true helium concentration.The spectrometer could become a prototype for the ITER charge-exchange recombination spectroscopy diagnostic and the pilot experiments, as presented here, demonstrate the possibility of impurity concentrations measurements based on the combined measurement of local beam emission and charge-exchange recombination spectroscopy spectra.

An improved lightweight network based on deep learning for grape recognition in unstructured environments

In unstructured environments,dense grape fruit growth and the presence of occlusion cause difficult recognition problems,which will seriously affect the performance of grape picking robots.To address these problems,this study improves the YOLOx-Tiny model and proposes a new grape detection model,YOLOX-RA,which can quickly and accurately identify densely growing and occluded grape bunches.The proposed YOLOX-RA model uses a 3×3 convolutional layer with a step size of 2 to replace the focal layer to reduce the computational burden.The CBS layer in the ResBlock_Body module of the second,third,and fourth layers of the backbone layer is removed,and the CSPLayer module is replaced by the ResBlock-M module to speed up the detection.An auxiliary network(AlNet)with the remaining network blocks was added after the ResBlock-M module to improve the detection accuracy.Two depth-separable convolutions(DsC)are used in the neck module layer to replace the normal convolution to reduce the computational cost.We evaluated the detection performance of SSD,YOLOv4 SSD,YOLOv4-Tiny,YOLO-Grape,YOLOv5-X,YOLOX-Tiny,and YOLOX-RA on a grape test set.The results show that the YOLOX-RA model has the best detection performance,achieving 88.75%mAP,a recognition speed of 84.88 FPS,and model size of 17.53 MB.It can accurately detect densely grown and shaded grape bunches,which can effectively improve the performance of the grape picking robot.

Recombinant protein production in the filamentous fungus Trichoderma

Trichoderma is an ascomycete fungal genus widely distributed in the soils.Several species were selected,engineered and utilized for protein production for decades.The high extracellular secretion capability and eukaryotic post-translational modification machinery make Trichoderma spp.particularly interesting hosts.In this review,we summarized the recombinant proteins produced in Trichoderma since 2014,concerning their origins,hosts,promoters,terminators,signal peptides,yields and commonly used media.Meanwhile,strategies and merging trends in protein production and strain engineering are classified and summarized regarding codon optimization,promoter utilization,transcription factor regulation,post-translational modification and proteolytic degradation inhibition.With state-of-art biotechnologies and more available expression platforms,Trichoderma spp.could be more successful hosts to produce recombinant proteins as desired,i.e.better enzyme formula for efficient cellulose degradation or functional protein with high purity and yield.

Low-velocity resistance distortion and bionic drag reduction for ship-type paddy field machinery

The resistance between mud surface and ship-type paddy field machine hull accounts for a certain proportion of the total mechanical power consumption during the operation process.The special characteristic has been found via preliminary study,it showed that when starting or working at low velocity,the resistance is much greater than the machine working at the rated velocity.This characteristic affects the dynamic matching and structural design of the machine.The critical velocity of resistance distortion was around 0.025 m/s under the setting experimental conditions,and the mechanism of resistance distortion under multi-medium was analyzed.Based on water film drag reduction theory,a macroscopic structure of crocodile's abdominal armor biomimetic drag reduction method was proposed.Two kinds of bionic macroscopic structure ship board were fabricated.The macroscopic structure can introduce more water into the bottom surface of the hull;thicken the water film,which can reduce the travel resistance.Design and manufacture a ship-type paddy field experimental setup with velocity control,and compare the traditional smooth surface ship board with the two bionic macroscopic structure surfaces through orthogonal test.The experiment results demonstrated that the ship board with rectangle gully structure has better drag reduction effect than the hexagon one in the lower velocity.But when the travel velocity approach to the resistance distortion critical point,the hexagon gully structure become better than the other one.Through the orthogonal test,the best drag reduction combination is 2.5 kg load weight,0.025 m/s travel velocity with hexagon ship board,which decreases the drag by 6.3%.