The extraction of lightning channels and the analysis of fractal dimensions are important topics in the field of lightning research. In this study, three high-speed optical images of negative cloud-to-ground flashes are preprocessed and then subjected to edge detection, contour search, and screening to extract the lightning channels. The results show that the lightning channels can be well separated from the background image. Using the box-counting method, the fractal dimensions of the extracted lightning images were calculated to be $1.31,1.31$, and 1.22, respectively. This study obtains the complex fractal dimension of the leader, which can provide basic parameters for the simulation of lightning leader development.

岩溶区覆盖层内土洞大量发育,土洞的失稳将威胁穿越该岩溶区的铁路交通正常运行,开展列车振动对既有土洞稳定性影响机制研究以提出有效监测建议对其防灾减灾有重要工程意义.依托武汉市江夏区乌龙泉岩溶塌陷实例,开展物理模型试验,探究列车振动荷载对土洞稳定性的影响机制,并用数值模拟分析其应力应变特征,据此提出有效监测建议.研究表明:覆盖层浅层的土压力动力响应较中深层更为敏感;在临界塌陷阶段,土洞背离路基侧较靠近侧具有更大的土压力波动;土洞破坏模式为:顶板弯折破坏,洞肩剪切破坏.据此提出以土洞顶板水平土压力减小和土洞背离路基侧洞肩土压力增大的重点监测部位和监测指标建议.

In the summer of 2019, one case of electric field sounding in eyewall of No.1907 typhoon named Wipha was obtained in Wenchang, Hainan Island, China. Up to now, it has been the first case of electric field sounding results obtained in a typhoon system. In this paper, based on the observations of satellite, meteorological radar, ground electric field and cloud-to-ground flash location data of Hainan province, China, the basic characteristics of the typhoon are analyzed in detail. Owing to the limitation of cloud-to-ground flash location system, only flash activities of the typhoon before and after landing period are analyzed and the result does not show obvious features as reported by other researches. Referring to the radar reflectivity and sounding path, we confirm that the sounding penetrates through the eyewall region of the typhoon from cloud base to top. The electric field profile and the charge region distribution in the sounding path area are analyzed, and the results show that four positive and three negative charge regions exist between 5.74 and 9.10 km above sea level and the corresponding temperatures range from –2.4 to –16.7 ℃ of the seven charge regions. The mean charge densities of each charge region from bottom to top are 0.63 nC/m3, –0.33 nC/m3, 0.31 nC/m3, –1.03 nC/m3, 1.70 nC/m3, 1.57 nC/m3 and –1.20 nC/m3, respectively. According to the preliminary analysis, we consider that the two positive charge layers at the top should be in the same charge region. Under the comprehensive consideration of the thickness of charge regions, the intensities of these six charge regions are 0.33 nC/m2, –0.07 nC/m2, 0.06 nC/m2, –0.87 nC/m2, 0.73 nC/m2, and –0.18 nC/m2, respectively. We can find that there are three dominant charge regions with largest intensity and they are the lowest positive charge region, the middle main negative region, and upper main positive charge region. And these vertical distributions of the three dominant charge regions are characterized by a tripole charge structure. These results are basically consistent with some simulation results. In addition, a negative screen charge region with a shallow depth in a range of 15–20 dBZ of the upper cloud boundary can be found. Combining the popular charging mechanisms, the similarity of tripole charge structure between our sounding and normal thunderstorm are discussed, and we preliminary consider that the non-inductive charging mechanism and the inductive charging mechanism, which originate from normal convection, are also suitable for eyewall region of typhoon.

In order to directly observe the electric field characteristics and study the charge structure in thunderstorms occurring in tropical regions, a balloon-borne strong electric field sounding is used to measure the vertical component of the electric field, temperature within the cloud and real-time location information of the sounding. Based on the principle of corona discharge, two 1-m-long metal probes are used as the sensors to detect the vertical electric field. In the summer of 2019, a result of electric field sounding within a local thunderstorm was obtained in the northeastern coastal area of Hainan Island, China. With the combination of an S-band weather radar, atmospheric electric field instrument and lightning locating network, the charge structure of the thunderstorm is analyzed in detail. The results show that the thunderstorm is a small-scaled local thunderstorm occurring in the afternoon, the sounding starting to be observed at the decay stage of the thunderstorm. In this period, lightning activities is rare, and the variation of ground electric field is similar to that of conventional summer thunderstorms. The whole sounding process lasts 34 min, during which the vertical airflow in the cloud is relatively stable, basically keeping 4–6 m/s. It can be seen from the electric field profile that the charge distribution in the thunderstorm cloud shows a complex charge structure which is composed of six charge regions. A negative charge region is lowermost, and above this the polarity alternates successively from bottom to up, where all charge regions are located above the melting-layer. Due to data interruption, it is impossible to accurately judge the upper boundary of the upper negative charge region and the information about the positive charge region above. The remaining charge regions are located in an altitude range of 6.0–6.3 km, 6.3–6.6 km, 6.9–7.3 km and 7.3–8.3 km, respectively. The charge densities in these four regions are –1.84 nC/m3, 1.80 nC/m3, –1.46 nC/m3, and 1.04 nC/m3, respectively. According to the existing data, the charge density of the uppermost negative charge area should be greater than –0.51 nC/m3. Moreover, the upper positive charge region (the fourth from bottom up) has the largest strength, followed by the negative charge region above it, both of which are more than 1 km in thickness. The electric field intensities in the other charge regions are relatively small. The pairs of positive and negative charge regions at the bottom are slightly different in strength and thickness.

A sounding system with electrical field and precipitation particles in thunderstorm is used for measuring humidity, temperature, the vertical component of electric field (E-field) and particle video. The ground system is used to continuously receive several signals sent by the sounding by tracking the GPS information carried by the sounding. This sounding system operated in a public frequency band of 2.4 GHz and used a fixed channel with the bandwidth of 20MHz to realize the point-to-point full-duplex communication. The ground system was connected to a parabolic directional antenna with high-gain of 27dBi. The real test showed that the maximum communication distance is about 15km which can well guarantee the field observation. The sounding was composed of GPS, temperature and humidity sensors, airborne vertical electric field measurement device, and precipitation particle video device.. GPS signal is very important for locating the balloon position and synchronously tracing sounding by antenna, and the measurement of vertical electric field used the corona probe as the sensor, and the ice phase precipitation particles were captured by a camera with frame rate of 25fl/s. A case of thunderstorm was obtained in the Pingliang of China. The results indicated that the balloon ascend through seven charge areas. A negative one located close to ground and a positive zone was above it in the warm cloud area. Other zones appeared at the area above melting layer and polarity of these was alternative changing. Another case showed the thunderstorm should have four charge regions with the lowest one is negative. However in actual observation, it still exists insufficient in recording the information of ice phase particles.

作为全球地层界线的唯一标准,"金钉子"的确立内涵丰富,意义重大,通过对"金钉子"剖面有关的实物地质资料进行系统的采集、集成和永久性馆藏,全面保存"金钉子"剖面的各类具代表性的实物地质材料和标本,对保全"金钉子"数据材料、诠释"金钉子"科学内涵、助推后续研究都具有重要意义.同时,便于同期地层剖面与之进行对比以强化其作为全球地层对比标准的地位,并可以为地质科学教学和科普工作起到立典和示范作用,使这一重大成果能更广范地运用到科研、生产和教学中.

This paper presents the design of a driving circuit for linear array CCD based on MCU.The system uses C8051F020 MCU as the slave computer to carry out CCD drive,signal collection,and communications with host computer.It solves the issues in driving a CCD,which a normal MCU can't deal with in a simple way.Large amount and repeated testing show that the design has high portability and operability and has been applied in some optical experiments perfectly and stably.

For the progressive failure landslide,the whole slope failure probability cannot reflect the internal failure development,while calculating the failure probability of every slice based on the slope progressive failure random principle can solve this problem effectively.Taking Zaozishuping landslide in Badong Couonty for example,this paper takes every single slope slice as the study object and calculates the safety margin and failure probability of every slice under different conditions on the basis of progressive failure model and Monte Carlo probability principle.The calculation results indicate that the failure probability of slices is different from each other under whatever conditions and the fluctuation of rainfall and reservoir water level will change the state of slice stability.Comparing the reservoir water level condition of 145 m and 175 m indicates that the failure probability of the front and trialing part are both declined,while the middle part is basicaly unchanged,so the whole stability is increased.Under the condition of 145 m reservoir water level and 50-year return period rainfall,the stability of almost every slice becomes worse and the slope fails from the front edge of landslide.The comparison of the progressive failure and whole failure probability shows that the former method can better reflect the slope stability state and it can contribute to the monitoring and prevention work of landslide.

This paper presents an image and location sensing system based on linear CCD.The system uses C8051F020 micro-controller as the lower computer to carry out CCD driving and communicating with upper computer,etc.The computer uses human-computer interaction software compiled by Labview to control the operation of the system;the upper computer and the lower computer are communicated via RS232 Interface.After testing,the system have obtained good results in onedimensional optical experiments such as interference;and the positioning accuracy of the position sensor is up to 140μm,positioning frequency is up to 50Hz or more.

By testing the luminous flux of the infrared light or infrared light distribution of the circumstances to reflect changes of the displacement is the basic methods of displacement monitoring.This paper uses two g infrared silicon to make a displacement sensor.By measuring the differential signal of the two silicon tubes we can measure the displacement.A constant current source circuit was design to reduce the noise.Finally,the signal noise was tested and the calibration of the design of the sensor was completed.

Treatment of 1800 mg/L phenols-containing coking wastewater by the ferric carbon micro electrolysis-Fenton reagent can satisfy the demand of the biochemical waste water disposing unit.Influences of the original pH,amount of H2O2,reaction time etc.on removal effect of the residual volatile phenols in the wastewater were studied.The optimal conditions were determined by orthogonal experiments as follows: the amount of H2O2 is 3.6 mL/L,the original pH is 3.0,the best reaction time is 180 min,respectively.After the wastewater is treated by flocculation under this conditions,the phenols degrading rate is 82%.

Automatic scanning and acquisition system of photoelectric signal is introduced,which is developed using C8051-F020 microcontroller.The system controls step motors and translation stages using C8051-F020 microcontroller.It collects signals from photoelectric sensors and transmits them to computer through RS232 to realize the spatial scanning of light intensity or the probing of spatial properties.In addition,the system control software,designed with the aid of LabVIEW,possesses the functions of virtual instrument.As a result,step motors can be operated intuitively and the photoelectric information obtained can also be displayed,processed and stored in real-time.

The software anti-jamming techniques usually applied in the aerospace site are discussed,including the software technique with time delay,the software anti-jamming methods of circuit,the software anti-jamming technology with program operation,the software anti-jamming technique in data acquisition,etc.Those measures can efficiently enhance the electromagnetic compatibility of the aerospace site.