Quantitative evaluation of adsorbed and free water in deep shales:a case study on the Wufeng-Longmaxi Formations from the Luzhou area,southern Sichuan Basin,China

Deep shale gas reservoirs commonly contain connate water, which affects the enrichment and migration of shale gas and has attracted the attention of many scholars. It is significant to quantitatively estimate the amounts of adsorbed and free water in shale matrix pores, considering the different impacts of pore water (adsorbed water and free water) on shale gas. In this paper, pore water in six deep shale samples from the Wufeng-Longmaxi Formations in the Luzhou area, southern Sichuan Basin, China, was quantitatively evaluated by saturation-centrifugation experiments. Further, the impact of shale material composition and microstructure on the pore water occurrence was analyzed. The results show that amounts of adsorbed and free water are respectively 1.7967–9.8218 mg/g (mean 6.4501 mg/g) and 9.5511–19.802 mg/g (mean 13.9541 mg/g) under the experimental conditions (30℃, distilled water). The ratio of adsorbed water to total water is 15.83%–42.61% (mean 30.45%). The amounts of adsorbed and free water are related to the pore microstructure and material compositions of shale. The specific surface area of shale controls the amount of adsorbed water, and the pore volume controls the amount of free water;organic pores developed in shale solid asphalt contribute specific surface area and pore volume, and inorganic pores developed in clay mineral contribute pore volume. Therefore, the pores of shale solid asphalt accumulate the adsorbed water and free water, and the pores of clay minerals mainly accumulate the free water.

Optimization of variables for maximizing efficacy and efficiency in aerial spray application to cotton using unmanned aerial systems

Aerial spraying can support efficient defoliation without crop contact.With the recent introduction to unmanned aerial system(UAS)for aerial spraying in China,there is a need to determine the optimum application variables to achieve high efficacy and efficiency with low costs.The present research involved field studies across two annual cotton production seasons in North Xinjiang,China.Four factors,including volume rate(A),tank mix including spray adjuvants(B),flight altitude(C),flight speed(D)and three levels of L9(3^(4))orthogonal arrays were carried out to optimize the application parameters for three types of UASs.These included different numbers of rotors as follows:four-rotors,six-rotors and eight-rotors.Spray coverage,distribution uniformity(coefficient of variation(CV)of droplet coverage),rates of cotton defoliation and boll opening,application efficiency and cost were measured and assessed.Results showed that:(1)the rates of defoliation and boll opening by aerial cotton defoliant application could meet the requirement of cotton mechanized harvesting;(2)the optimal scenario for the three UASs was A_(3)B_(2)C_(1)D_(3),Volume rate(A3):48 L/hm^(2);Tank mix and concentration(B_(2)):(Tuotulong 225+Sujie 750+Ethephon 2250)mL/hm^(2),Flight altitude(C_(1)):1.5 m,and Flight speeds(D_(3))for unmanned helicopters with four-rotors,six-rotors and eight-rotors were 3.12 m/s,2.51 m/s and 3.76 m/s,respectively.These results can provide guidance for cotton defoliant aerial spraying in China using UAS.

Development of UAV-based shot seeding device for rice planting

In order to realize the high-quality row seeding operation with unmanned aerial vehicle(UAV)in paddy field,a shot seeding device that can sow five rows of pelleted rice seeds at the same time was designed.The shot seeding device mainly consists of an external grooved wheel seed metering device and five shot seeding modules.The designed external grooved wheel seed metering device can take the seeds out of the seed box and divide the seeds into five parts.The shot seeding module can accelerate the pelleted rice seeds to reduce the impact of the UAV wind on the direction of seed movement.Furthermore,an angle adjustment mechanism for the shot seeding module was used to change the row spacing.The seed metering device test verified that when the speed of the seed metering wheel was 15 r/min,the coefficient of variation of the discharge rate of each row(C.V1)and total seed discharge rate stability(C.V2)were 1.70%and 1.04%,respectively.Image processing technique was used to test the UAV seeding performance.The distribution characteristics of seeds on the ground showed that the number of seeds in each row gradually increased from both sides to the middle in the width direction.According to the statistics,there were 60%-70%of the seeds in each row in the 100 mm width range.The field test showed that when the working height was 1.5 m and the seeding quantity was 38.56 kg/hm^(2),the performance of sowing in rows was obvious,the deviation rate of seeding quantity was 1.89%.After 16 d of sowing,the seeds’emergence rate was stable,and the average emergence rate was 82.63%and the yield was 6775.50 kg/hm^(2).

Design and anti-sway performance testing of pesticide tanks in spraying UAVs

Anti-sway performance is one of the most important factors that affect the stability of unmanned aerial vehicles(UAVs).In this study,an anti-sway performance testing method and an evaluation formula for pesticide tanks were developed,which could facilitate the design and application of pesticide tank.The detection device mainly comprises a testing stand,a mounting and testing part,and a driving and control part.In the testing method,P(maximum pressure)measured by a barometer and t(fluctuation recovery time)measured by a high-speed camera were used as evaluation indexes.With the aim to determine the optimal position of the pressure detection device and the optimal filling ratio,four representative pesticide tanks were involved in this study.The results showed that the optimal position of the pressure detection device was at the middle position on the tank wall,halfway up from the bottom,and the optimal filling ratio was 0.8.Using P and t as evaluation indexes,a comprehensive evaluation formula was developed based on these tests:S=0.7Pi+0.3ti.Anti-sway performance of pesticide tanks was evaluated by a comprehensive score.A disk pesticide tank with a baffle was determined to be the best among the four types of pesticide tanks,showing a score of 1.The scores of the other three pesticide tanks were 0.500,0.428 and 0.612,respectively.These results indicated that the baffle structure in the pesticide tank and the radian design of the tank wall can effectively improve the anti-sway performance of a pesticide tank.The proposed detection device and test method are simpler and more intuitive compared to other approaches in evaluating the anti-sway performance of pesticide tanks in spraying UAVs,and they can be used as a reference to guide the design of pesticide tanks and the stability evaluation of spraying UAVs.

Research advances of the drift reducing technologies in application of agricultural aviation spraying

With the gradual deterioration of the ecological environment and the increase in requirements for the quality of modern life,the use of pesticides is bound to develop towards higher pesticide utilization and less environmental pollution,and the low-volume spraying for agricultural aviation operation combined with the Drift Reducing Technologies(DRTs)may be a useful way to achieve this goal.Based on an analysis of the spray drift mechanism and the primary factors influencing aerial spraying,previous research on DRTs in aerial spraying were reviewed and summarized,and it was found that DRTs in aerial spraying can effectively reduce the environmental pollution caused by pesticide drift by reducing the spraying amount of pesticides and improving the control effect of pesticides,included aerial electrostatic spray technology,aerial spray adjuvant,aerial air-assisted spray technology,drift reducing nozzles and aerial variable-rate spray technology.And according to the analysis of the current research status,some suggestions and countermeasures to reduce droplet drift of agricultural aviation spraying were put forward from the aspects of strengthening the research on DRTs for plant protection Unmanned Aerial Vehicle(UAV)and adopting reasonable DRTs methods.It is hoped that provide reference and guidance for the enterprises’product improvement and users’practical operation,and play the advantages of precision agricultural aviation spraying fully.

Discharge rate consistency of each channel for UAV-based pneumatic granular fertilizer spreader

Unmanned aerial vehicles(UAVs)are widely being used to spread granular fertilizer in China.Granular fertilizer spreaders equipped with UAVs are mainly centrifugal disc-type and pneumatic.The multichannel pneumatic granular fertilizer spreaders(MPGFSs)have a banded fertilizer deposition distribution pattern,which are more suitable for variable rate fertilization with high precision requirement than the circular deposition distribution pattern of disc-type granular fertilizer spreaders(DGFSs).However,the existing MPGFS has the disadvantage of inconsistent discharge rate of each channel,which affects the uniformity of fertilization.In order to explore the causes of inconsistent discharge rate of each channel,the discrete element method(DEM)and bench test were performed to analysis the discharge process of the fluted roller fertilizing apparatus and distribution of fertilizer in axial direction of fluted roller.The computational fluid dynamics(CFD)was used to simulate the airflow field of pneumatic system to analyze the influence of airflow on the movement of fertilizer particles.The simulation results of the discharge process of the fluted roller fertilizing apparatus showed that the filling velocity at the axial ends of the fluted roller fertilizing apparatus was lower than that of the middle.The reason was that the filling capacity was weak near the wall.The simulated results of the airflow field without partitions showed that the airflow provided by the axial flow fan was rotational,and this caused the particles to move irregularly in the throat,resulting in inconsistency discharge rate of each channel.Based on the analysis of reasons of inconsistent discharge rate of each channel,a MPGFS with partitions in the throat was developed.The discharge rate bench tests were carried out to optimize the partition spacing parameters,and fertilization test was performed to test the performance of the improved MPGFS.The discharge rate test results showed better consistency with partition.The coefficient of variation(CV)of the discharge rate of each channel was 20.16%without the partition and 7.70%with the optimal partition.The fertilizer spreading uniformity bench test results shown that the CV of spreading uniformity of MPGFS without partitions was 15.32%,and that MPGFS with partitions was 8.69%.The partitions design was beneficial to improve the consistency of each channel discharge rate and the uniformity of fertilization.The finding can provide a strong reference to design the MPGFS.

Optimization of aviation adjuvants based on wettability analysis for insecticide application on maize using UAV

Adjuvants can increase the control efficacy of diseases and insect pests by changing the physico-chemical properties of pesticides.Most of the aviation spray adjuvants are versions of ground adjuvants.Maize insecticide sprays with unmanned aerial vehicles(UAV),have problems such as relatively low droplet deposition rate and poor wettability.Hence,wettability research and optimization tests for aviation spray adjuvants are needed.The present study screened 12 spray adjuvants using physico-chemical property experiments.The adjuvants were applied to improve the droplet deposition and control efficacy in maize borers controlling by UAV.The selected spray adjuvants were Po2(a hyperbranched polymer adjuvant)and VO3(a vegetable oil adjuvant).Results showed that,(1)When Po2 was added in water-dispersible granules(WGs)at volume rate of 12 L/hm2,the dynamic surface tension(DST)of WGs was decreased by 37.41%,and the maize leaves were covered by droplets 100%,the droplet deposition was increased by 104%and maize borer control was increased by 46%;(2)VO3 decreased the surface tension of ultra-low-volume(ULV)formulation by 12.02%and the maize leaves were covered by droplets 100%.The effect of VO3 on improving the droplet deposition and control efficacy at 12 L/hm2 with ULV was not significant.Thus,the addition of aviation spray adjuvant to improve the wettability of WGs significantly improved the droplet deposition and control efficacy but it had no significant effect on the ULV formulation.

Laser tracking leader-follower automatic cooperative navigation system for UAVs

Currently,small payload and short endurance are the main problems of a single UAV in agricultural applications,especially in large-scale farmland.It is one of the important methods to solve the above problems of UAVs by improving operation efficiency through multi-UAV cooperative navigation.This study proposed a laser tracking leader-follower automatic cooperative navigation system for multi-UAVs.The leader in the cluster fires a laser beam to irradiate the follower,and the follower performs a visual tracking flight according to the light spot at the relative position of the laser tracking device.Based on the existing kernel correlation filter(KCF)tracking algorithm,an improved KCF real-time spot tracking method was proposed.Compared with the traditional KCF tracking algorithm,the recognition and tracking rate of the optimized algorithm was increased from 70%to 95%in indoor environment,and was increased from 20%to 90%in outdoor environment.The navigation control method was studied from two aspects:the distance coordinate transformation model based on micro-gyroscope and navigation control strategy.The error of spot position was reduced from the maximum(3.12,−3.66)cm to(0.14,0.12)cm by correcting the deviation distance of the spot at different angles through a coordinate correction algorithm.An image coordinate conversion model was established for a complementary metal-oxide-semiconductor(CMOS)camera and laser receiving device at different mounting distances.The laser receiving device was divided into four regions,S0-S3,and the speed of the four regions is calculated using an uncontrollable discrete Kalman filter.The outdoor flight experiments of two UAVs were carried out outdoors using this system.The experiment results show that the average flight error of the two UAVs on the X-axis is 5.2 cm,and the coefficient of variation is 0.0181.The average flight error on the Z-axis is 7.3 cm,and the coefficient of variation is 0.0414.This study demonstrated the possibility and adaptability of the developed system to achieve multi-UAVs cooperative navigation.

Fish as a source of acoustic signal measurement in an aquaculture tank:Acoustic sensor based time frequency analysis

Acoustic signals travels rapidly in water without attenuating fish telemetry.The digital sonar and passive acoustic has been used for fish monitoring and fish feeding.However,it is an urgent need to introduce new techniques in order to monitor the growth rate of fish during harvesting and without causing adverse effects to the harvested fish.Therefore,a novel technique was introduced to probe the acoustic signal frequency ratio in absence and presence of the fish in tanks,which basically uses an acoustic sensor(hydrophone),acoustic signal processing system(scope meter),and a signal monitoring system(fluke view).Acoustic signals were selected from 48-52 Hz frequency,measure of dispersion of frequency signal represented as a function of time via Xlstat software.Measure of dispersion displayed a significant effect of acoustic signal in the presence and absence of the fish in tanks.These optimised protocols of this study will help to control and prevent excessive wastage of feed and enhance proper utilization of feed that chiefly enhance fish growth in aquaculture.

Design and test of centrifugal disc type sowing device for unmanned helicopter

In China,it is difficult for manned aircraft to sow seeds in small and scattered plots,especially in areas including hills,swamps,telegraph poles,windbreaks,and residential areas;in such terrain,the sowing machinery cannot function properly.However,unmanned helicopters(UHs)are flexible enough to control and adapt to the complex environments that are not easily accessible by terrain sowing machinery and large agricultural aircraft,which have been widely used in agriculture.In this study,a centrifugal disc-type sowing device for an unmanned helicopter(CDTSDUH)was designed.The factors influencing the seed velocity when the seeds move away from the disc were explored by analyzing the forces of the seed acting on the sowing disc and the wind field of the UHs.The influential factors include the distance from the falling mouth to the center of the disc,the offset angle of the falling mouth,and the rotation speed of the disc.An orthogonal test was designed with the sowing width and the curvature of the sowing area as the indexes.The test results showed that the three factors mentioned above had a greater impact on the sowing width than the curvature of the seeding area.Moreover,the superior parameters of the disc were determined.It was also suggested that the above factor levels had little effect on the offset width of sowing.The results of the test conducted for studying the sowing uniformity of the CDTSDUH indicated that the maximum and minimum difference values among the number of particles of the sampling points in the forward direction was 11 and 8,and the coefficient of variation of the number of particles in each row was more than 20%,indicating less uniformity was achieved when sowing in the lateral(perpendicular to the forward direction)direction,as compared to that in the forward direction.This study determined the ideal values for the radius of particles position,the offsetting angle,and the disc speed of the sowing machinery designed.Furthermore,considering that there are so many factors that influence the manner in which a UH functions,more analysis results and test data of influencing factors need to be acquired by experiments.The uniformity of sowing needs to be further improved.The results provided some theoretical and experimental references for the technology research on the centrifugal disc-type sowing device for UHs.

Test and evaluation method for endurance performance of electric multi-rotors spraying drones

The endurance performance(EP)of electric multi-rotors spraying drones(EMSDs)is a key technical indicator that ensures the completion of tasks and improves their usefulness.To improve the EP of current EMSD,a test system was designed to determine the EP based on the EMSD test platform,and the performance evaluation method was studied.Firstly,a test model was established to determine the equivalent energy dissipation using the performance-testing platform of the EMSD.Secondly,a multisensory test system was constructed.An attitude sensor,high-power DC power supply,infrared thermal imager,and serial port server were selected.The mounting fixture was designed to meet the universal mounting requirements of drone.In addition,the software LabVIEW was employed to program the code for the controller and the host computer,where functions such as data collection,data processing,communication,and graphical user interface(GUI),were performed reliably in real time.Thirdly,the test method was explored by considering factors such as the power consumption,thermal efficiency ratio,and unit load power consumption rate.In particular,a comprehensive index method and expert consultation weight method were used to evaluate the EP of the EMSD with multiple indexes.Finally,a systematic real-machine test was carried out on the three types of drones that are currently widely used in the market.The results verified the effectiveness and feasibility of the proposed method,which was employed to test and evaluate the EP based on the EMSD performance testing platform.At the same time,it can provide a reference for the development of the EMSD.

Development of droplet characteristics prediction models for air induction nozzles based on wind tunnel tests

Nozzle flowrate and spray pressure are two of the most important factors influencing on droplet characteristics.With the aim to develop prediction models for air-induction nozzles(AINs),a series of Billericay Farm Services(BFS)AINs with different orifice diameters in combination with tap water were tested.0.2 MPa,0.3 MPa,0.4 MPa,0.5 MPa,0.6 MPa and 0.7 MPa of spray pressures and 2 m/s,3 m/s,4 m/s and 5 m/s of air speeds were setup.Based on the wind tunnel tests data,prediction models with input variables of nozzle flowrate and spray pressure and output variables of D_(v0.1),D_(v0.5),D_(v0.9),%<150μm(proportion of spray volume contained in droplets with diameter below 150μm),relative span(RS)and coefficient of variation(CV)of D_(v0.5) were developed.The developed models were validated based on wind tunnel experimental data.Results showed that:for D_(v0.1),D_(v0.5),D_(v0.9) and%<150μm,R^(2) were equal to 0.768,0.823,0.868 and 0.811,indicating that the predictive ability for these four parameters is strong.For RS and CV,R^(2) were equal to 0.100 and 0.113,respectively,indicating that the predictive ability for these two parameters is poor.The models developed in the present study are helpful for facilitating the use of AIN in agricultural spray application.