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In order to study the corrosion behavior of L360 steel at the pipe wall of water-containing gathering and transportation pipelines under real flow conditions， a self-made cyclic flow corrosion test device was used.The electrochemical impedance spectroscopy and potentiodynamic scanning methods were used to analyze the corrosion electrochemical characteristics of L360 steel.The scanning electron microscope and three-dimensional optical microscope were used to analyze the corrosion micromorphology.Results showed that the average corrosion rate of the test piece increased with the increase of flow rate，and the local corrosion rate presented a trend of first decreasing and then increasing.Properly increasing the flow rate could slow down the local corrosion rate.After the loop was run for 4 h， a relatively complete corrosion product film began to form on the surface of the sample.When the flow rate reached 0.5 m/s， the corrosion product film on the pipe wall began to detach.For clean and smooth samples， the initial stage of corrosion belonged to extremely severe corrosion.

【Objective】Single-photon detection and single-photon ranging systems have widespread applications in three-dimensional imaging and long-distance spatial remote sensing. However, device limitations and background noise from the sun light limit the application to only nighttime conditions.【Methods】We have improved traditional laser radar systems by implementing all-fiber optics systems with ultra-narrowband fiber optic filtering, leading to significantly improved system stability. By implementing mechanical motion control, we are able to attain single-photon imaging systems with ultra-wide scanning and ultra-high resolution. The systems can operate in optical environments that are typically challenging, such as daytime or foggy weather. Moreover, the laser radar system is designed based on the 1 550 nm wavelength which has good atmospheric penetration and low transmission loss, enhancing its ability to work in foggy and rainy conditions.【Results】In a foggy condition with a visibility of about 500 m, the system achieves three-dimensional imaging of objects 1.6 km away, which is a distance 3 times longer than the visibility at the time. The distance resolution can be significantly enhanced by optimizing the intensity and distance information of the histogram using the minimized negative logarithmic likelihood function, with the assistance of a high-resolution time/digital converter and the model constructed by the system response function of the laser radar. Compared to the maximum value method with a distance resolution of 0.05 m, this system achieves a distance resolution of 0.006 m via the minimized negative logarithmic likelihood function method. Additionally, the image normalization processing is performed to suppress fluctuations in photon technology and eliminate noise in the image. The 1 550 nm all-fiber laser radar system has strong mechanical stability and can work in adverse weather conditions.【Conclusion】It has significant application value in remote sensing and mapping, ground and vehicle-mounted laser radar, and other fields.

【Objective】The optical communication system working at the traditional telecommunication band is faced with "capacity crunch" with the rapidly development of optical communication technology. The acceptable loss of 0.2 dB/km (@2 μm) from the hollow-core photonic bandgap fibers as well as the high optical amplification gains (30 dB@2 μm) of thulium-doped fiber amplifiers (CTFA type) provides the potential for the 2 μm wavelength band to alleviate the communication "capacity crunch". As a result, the needs of the 2 μm silicon-based photodetectors is also raised due to its mature and convenient manufacture process. The main solutions of the silicon-based photodetectors include the usage of Ⅲ-Ⅴ compounds with tunable band gap, the introduction of low band gap width materials as absorption regions, the use of new absorption mechanism in optical absorbed material at the 2 μm wavelength band and so on. The Ge material has a high Two Photon Absorption (TPA) coefficient (1 225 GW/cm@2 μm). And the Ge-on-Silicon-On-Insulator (SOI) photodetector is an excellent method to realize 2 μm optical signal detection, which is compatible with the standard silicon photonics device manufacturing process that has the advantages of low production difficulty and cost. The purpose of this paper is to verify the feasibility of the Ge-on-SOI photodetector to achieve 2 μm wavelength band photoelectric detection by using the special optical absorption mechanism of TPA.【Methods】In this paper, the photoelectric detection at the 2 μm wavelength band based on the physical absorption mechanism of current generated from high TPA of Ge material is realized. The quantification of the photocurrent generated by Ge material through TPA effect is analyzed and discussed in this paper. In the experimental test, we first apply a high power 2 μm wavelength band input light source magnified by thulium-doped fiber amplifiers to the input port (grating coupler) of the commercial waveguide-type Ge-on-SOI photodetector in the on-chip active silicon photonics device test system. Then we adjust the alignment of the optical fiber with the grating coupler and the input light polarization to reduce the optical transmission loss from the input optical fiber to the Ge absorption region. Finally, the TPA photocurrent of the on-chip photodetector is obtained by a probe.【Results】A net photogenerated current up to 651 nA and an estimated value of responsivity greater than 10 mA/W is obtained experimentally under a 2 μm wavelength optical input power of 21.9 dBm.【Conclusion】The work of this paper verifies the scientific feasibility of 2 μm waveband photodetector through the TPA effect of Ge material, and provides experimentally support for the design of the 2 μm wavelength band Ge-on-SOI photodetector based on TPA.

In this study, the optimal concentrations of methyl jasmonate (MeJA) and methyl dihydrojasmonate (MDJA) for Cabernet Gernischt were selected based on basic physicochemical properties of grapes. The key volatile metabolites and key enzyme activities in response to MeJA and MDJA were analyzed by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and enzyme-linked immunosorbent assay (ELISA), respectively. The effects of pre-harvest MeJA or MDJA treatment on the fruit quality and green leaf volatile components in the lipoxygenase (LOX) metabolic pathway of Cabernet Gernischt were also investigated. The findings revealed that the application of 0.1 mmol/L MeJA or 5 mmol/L MDJA significantly enhanced mass of 100 berries, total sugar content, soluble solids content, pH, total phenol and total anthocyanin contents. Compared with the control group, MeJA increased these indexes by 10.24%, 27.83%, 28.24%, 4.80%, 77.63% and 85.29%, respectively, while MDJA increased them by 9.15%, 24.01%, 24.41%, 8.30%, 69.21% and 71.57%, respectively. Furthermore, MeJA and MDJA reduced titratable acid content by 40.0% and 30.24%, respectively. Accordingly, both MeJA and MDJA significantly improved fruit quality. Moreover, they significantly increased the contents of C6 compounds responsible for the typical aroma of Cabernet Gernischet. Significant correlations were observed between the activity of each key enzyme in the lipoxygenase metabolic pathway and the corresponding metabolites, indicating that the application of MeJA or MDJA at a suitable concentration could positively influence the accumulation of green leaf volatiles in Cabernet Gernischt.

【Objective】High-frequency microwave carriers (GHz) with tunable capability have a wide range of applications in 5th Generation Mobile Communication Technology (5G)/ 6th Generation Mobile Communication Technology (6G) wireless networks, radar systems, and satellite communications. Due to the relatively simple structure of the system, the large bandwidth and the low loss, the technical scheme of generating high-frequency tunable microwave carriers based on photonic technology has attracted extensive attention from domestic and international research teams. Current photogenerated microwave experiments are mostly conducted in C-band wavelengths because of the mature commercial devices. Meanwhile, the Wavelength Division Multiplexing (WDM)-Radio Over Fiber (ROF) technology integrates the WDM technology with the ROF technology so as to flexibly realize the combining/splitting of microwave bands with the help of the combining/splitting of WDM system in the optical frequency domain. The ROF part of the system employs photogenerated microwave technology to simplify the base station configuration. Constrained by the limited bandwidth resources in the C-band wavelengths(35 nm, 1 530~1 565 nm), there is a drive for the generation of microwave to expand to wider spectral ranges. The U-band wavelengths can also provide channel bandwidths as wide as 50 nm (1 625~1 675 nm) to alleviate the channel utilization pressure in the C-band wavelengths; In the U-band wavelengths, Standard Single Mode Fibers(SSMFs) have achieved optical power loss as low as 0.195 dB/km (@1 625 nm); In particular, thulium-doped fiber amplifiers have also demonstrated a large bandwidth gain of 18.7 dB (@1 655 nm). These advantages attract SSMFs-based WDM systems to expand into the U-band, which leads to the extension of WDM-ROF technology into long wavelengths, and in turn leads to the expansion of photogenerated microwave technology. Therefore, this paper studies the photogenerated microwave technology in the U-band.【Methods】From the mathematical model, the commonly used photogenerated microwave carriers technologies are transparent to the applied optical carrier bands, and can be used to generate microwave carriers at arbitrary bands by selecting photonics devices corresponding to the operating bands. In principle, C-band wavelengths photonics devices (such as polarization controllers, Phase Modulator (PM), Fiber Phase Shifter (FPS), etc.) can work in the U-band, and the process technology of these devices is mature. Therefore, in this paper, photonics devices such as C-band wavelengths PM, FPS and optocouplers are used to build a photogenerated microwave carrier system based on U-band optical carriers.【Results】Finally, tunable microwave carrier with a tuning range of 7.5~12.0 GHz and a spurious rejection ratio of 29.6~35.2 dB is ultimately generated based on this system.【Conclusion】Through formula principle analysis and experimental verification, this paper extends the working band wavelengths of the photogenerated microwave carrier to the U-band wavelengths.

Considering that some tasks will require the consistency of the position and attitude of the end-effector, multi-space-robot cooperative capture also needs to consider the synchronization of the two capture arms. Taking the dual-space robots as example, the trajectory planning problem before cooperative capture is focused. First, a drive-transform method based on trapezoidal velocity interpolation is proposed, which combines the advantages of these two methods to obtain the SE(3) motion trajectory, in which the attitude and position are planned synchronously. Then, the trajectory optimization model of cooperative capture is established, which takes the optimal time and the minimum attitude disturbance of the base as the optimization goals, and simultaneously satisfies that the two capture arms reach the capture point synchronously. In order to solve this multi-objective optimization problem, a dual-population multi-objective fruit fly algorithm based on non-dominated sorting was proposed. Finally, the simulation example of dual-space robots shows that the proposed algorithm is effective, and the analysis of the optimal solution set demonstrates that the optimized cooperative capture trajectory is smooth and synchronous.

Adding corrosion inhibitor is one of the conventional methods to slow down the corrosion of the gathering and transportation system in oil and gas fields, as this method has the advantages of low cost, high efficiency, easy operation and having no effect on the basic properties of the medium. However, the on - site pipeline transportation environment is complex, and the corrosion inhibition efficiency is affected by many factors. In this paper, the influence rules of corrosion inhibitor properties, pipeline materials and environment on corrosion inhibition efficiency were reviewed. Results showed that there were many factors affecting corrosion inhibition efficiency and the rules were complex, which needed to be analyzed according to the actual situation. There were few studies on interaction effects of various parameters. In addition, the commonly used laboratory evaluation methods of corrosion inhibitors were summarized. At present, the evaluation methods of corrosion inhibitors mainly include weight loss method, electrochemical evaluation method, quantum chemical theory evaluation method, molecular dynamics simulation method and various surface analysis methods such as scanning electron microscopy (SEM), energy dispersive analysis (EDS), X - ray diffraction (XRD), X - ray photoelectron spectroscopy (XPS), 3D microscopy, atomic force microscopy (AFM) and electrochemical quartz crystal microbalance (EQCM). Finally, the development direction of corrosion inhibitors, the research on the main controlling factors affecting the corrosion inhibition efficiency, and the evaluation methods of corrosion inhibition efficiency were prospected. In order to make the screening and evaluation of corrosion inhibitors more consist with the actual situation, the corrosion inhibition efficiency should be evaluated under the pre - corrosion condition in a flowing environment, and the local corrosion rate should be paid attention to. Also, the importance of finding the key factors affecting the corrosion inhibition efficiency was pointed out.

Because of the problem of local scour caused by the change of the flow structure caused by the water-resistance of the column bridge pier, the theoretical analysis, and indoor water tank test were used to study the effect of installing a new anti-scouring device in front of the bridge pier on the local scour reduction effect; the influence of the main design parameters such as the height of the protective device, the angle of the protective device and the distance from the protective device to the bridge pier on the local scour of the bridge pier was selected, and the optimal parameter design combination was selected. The test results show that: under the same water flow conditions, the maximum scour depth reduction rate of the measuring point under the protection of the protective device is 48.4% to 74.2% compared with the unprotected scour; the reduction rate of the bridge pier is relative to the relative height of the device and the device equivalent. The angle and the distance between the device and the bridge pier are related, and the shock reduction rate decreases with the increase of the flow intensity. In the test range, the ratio of the device height to the water depth is 2/3, the device angle is 60 °, and the distance from the bridge pier is 3. When the diameter of the pier is doubled, the effect of reducing the impact on the pier is the best.