The downslope movement of detached rock blocks along steep slopes is an important process endangering the safety of infrastructure along the foot of a slope and on the valley bottom,but only limited knowledge is avail...The downslope movement of detached rock blocks along steep slopes is an important process endangering the safety of infrastructure along the foot of a slope and on the valley bottom,but only limited knowledge is available on the influence of various factors on the velocity and distance of movement of such blocks.We discuss the influence of the mass and shape of the rock blocks,the steepness of the slope,and the thickness of the overburden on the slope,on the distance of movement of rock blocks which was observed in 256 field experiments with differently shaped blocks from 3 different positions on the slope with a height of 176 m.The statistical evaluation of the results of the field tests shows that the slope condition of gradient and overburden is the main factor,the form of rock masses is the second factor,and the mass is the third of the influencing factors.It is the maximum average acceleration for movement of rock masses when the mass of rock masses is 15≤m27 kg,the form of rock masses is flake,the condition of gradient is on average 59.6° and the overburden is basic exposed bedrock and a small quantity of gravel-soil in the experiment condition.It is the minimum average acceleration for movement of rock masses when the mass of rock masses is 9.5≤m15 kg,the form of rock masses is rectangular,the condition of gradient is on average 39° and the overburden is gravel-soil and cinder.Then,the foundation for impact energy is provided and the new feasible methods to prevent potential unstable rock masses are put forward.展开更多
Late blight caused by <i>Phytophthora</i> <i>infestans</i> (Mont.) De Bary is the most devastating disease of potato. This study was carried out to evaluate the efficacy of ten botanical extrac...Late blight caused by <i>Phytophthora</i> <i>infestans</i> (Mont.) De Bary is the most devastating disease of potato. This study was carried out to evaluate the efficacy of ten botanical extracts against the late blight disease incidence and severity in experimental potato field at University of Rajshahi, Bangladesh during 2019-2020. Crude aqueous extract of leaves of <i>Syzygium</i> <i>cumini</i>, <i>Psidium</i> <i>guajava</i>, <i>Eucalyptus</i> <i>globusus</i>, <i>Carica</i> <i>papaya</i> and <i>Lawsonia</i> <i>inermis</i>;fruits of <i>Terminalia</i> <i>bellirica</i>, <i>T.</i> <i>chebula</i> and <i>Piper</i> <i>nigrum</i>;flower buds of <i>Syzygium</i> <i>aromaticum</i> and cloves of <i>Allium</i> <i>sativum</i> were used at 5% (w/v) concentration for evaluation. Out of ten botanicals, <i>Syzygium</i> <i>cumini</i> leaves extract was found most effective in controlling the late blight disease incidence and severity up to 66 DAS (days after sowing) and increased the potato yield by 71.29% compare to untreated control. The efficacy of <i>Lawsonia</i> <i>inermis</i> extract against late blight disease was found promising and increased the potato yield by 48.51%. Other four botanical extracts (<i>Terminalia</i> <i>chebula</i>, <i>Piper</i> <i>nigrum</i>, <i>Syzygium</i> <i>aromaticum</i> and <i>Carica</i> <i>papaya</i>) showed moderate efficacy <span>against the incidence and severity of late blight disease, and increased 30% </span>more potato yield compare to control. These results suggest that botanical extract of <i>Syzygium</i> <i>cumini</i> ha<span style="font-family:;" "="">s</span><span style="font-family:;" "=""> a great potential as an alternative </span><span style="font-family:;" "="">of</span><span style="font-family:;" "=""> chemical fungicides to control the late blight disease of potato in</span><span style="font-family:;" "=""> </span><span style="font-family:;" "="">eco-friendly way.</span>展开更多
We propose optical experiments to study the depth of field for a thermal light lensless ghost imaging system. It is proved that the diaphragm is an important factor to influence the depth of field, and the ghost image...We propose optical experiments to study the depth of field for a thermal light lensless ghost imaging system. It is proved that the diaphragm is an important factor to influence the depth of field, and the ghost images of two detected objects with longitudinal distance less than the depth of field can be achieved simultaneously. The longitudinal coherence scale of the thermal light lensless ghost imaging determines the depth of field. Theoretical analysis can well explain the experimental results.展开更多
In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high i...In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high identification to discontinuity are used to the numerical reconstruction of part of an actual hemispherical blast-wave flow field by properly adjusting the moving bounary conditions of a piston. This method is simple and reliable. It is suitable to the evaluation of effects of the blast-wave flow field away from the explosion center.展开更多
Amid the deepening global higher education reforms,developing innovative teaching models to enhance student academic performance and satisfaction has become a crucial research priority.This study uses a field experime...Amid the deepening global higher education reforms,developing innovative teaching models to enhance student academic performance and satisfaction has become a crucial research priority.This study uses a field experiment to evaluate the impact of the industry-university-research collaborative teaching(IURCT)model on students’performance and satisfaction.Comparing the Learning Assessment Score(LAS)and Satisfaction Score(SS)of the IURCT model with those of the traditional teaching methods,the experimental results showed that both LAS and SS were significantly higher for students in the IURCT model,and the effects continued to strengthen over the intervention period.Mechanism tests reveal that the IURCT model enhances the LAS and SS by boosting learning motivation,providing personalized support,and offering psychological support.Furthermore,heterogeneity analysis indicates that the IURCT model’s vary across gender,region,and academic levels.This study provides empirical support for the application of the IURCT model in education and offers valuable insights for policymakers to optimize teaching models.展开更多
As the commercialization of the fifth gen-eration communication(5G)is sped up,its system testing scheme is vital for the successful deployment of 5G.Especially,5G relies on the scale-increased multiple-input-multiple ...As the commercialization of the fifth gen-eration communication(5G)is sped up,its system testing scheme is vital for the successful deployment of 5G.Especially,5G relies on the scale-increased multiple-input-multiple output(MIMO)technique to improve its capacity and coverage.Thus,testing new functions of the 5G MIMO system accurately and ef-ficiently,including beamforming(beam-tracking with movement)and multiple-user(MU)multiplexing,is a challenging task.This paper tries to construct a lab-oratorial hardware and conduct equipment-controlled field testing.Firstly,the testing scheme is presented,which is composed of the framework,the channel models and the validation methods.Then,the channel model principles are explained in detail due to its di-rect influence on the testing accuracy.Specifically,we utilize the spatial consistency and the multi-link cor-relation properties to emulate the high-speed dynamic time-varying(HDT)and the multiple-cell(MC)-MU-MIMO channels.Finally,the above testing scheme is verified in a Shanghai 5G field experiment with the practical commercial equipment and the channel em-ulator.The results show that the 5G new functions are tested accurately and efficiently by switching the channel emulation configurations.展开更多
[Objective] The aim was to study the effect of three new fungicides against rice sheath blight in field experiment. [Methods] The experiment set up 7 treatments with three times of repetition and designed by random gr...[Objective] The aim was to study the effect of three new fungicides against rice sheath blight in field experiment. [Methods] The experiment set up 7 treatments with three times of repetition and designed by random grouping. By using 5 sampling points in each plot, and investigating continuous 4 holes of each point, total plants, diseased plants and disease degrees were recorded. Then disease index and control efficiency were calculated, and variance analysis was carried out. [Results] 300 or 450 ml/hm^2 azoxystrobin ＋ difenoconazole 325 g/L SC had better control efficiency to rice sheath blight and had no phytotoxicity effect, we should use it at the initial disease stage and continuously spray 2-3 times. [Conclusion] The experiment provided a theoretical basis for controlling rice sheath blight using fungicides.展开更多
In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure ...In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure near the Beijing- Guangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building floors increase with train speed, and attenuate with the distance to the railway track. Heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with floor elevation, while the vertical ones increase with floor elevation in a fluctuating manner. The indoor floor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater floor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration （FTA） criteria for acceptable ground-borne vibrations expressed in terms ofrms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.展开更多
Soil organic carbon （SOC） is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields because of their vest expan...Soil organic carbon （SOC） is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields because of their vest expansion in south China. A study was carried out to evaluate the relationship between the SOC content and organic carbon input under various organic amendments at a long-term fertilization experiment that was established on a red soil under a double rice cropping system in 1981. The treatments included non-fertilization （CK）, nitrogen-phosphorus-potassium fertilization in early rice only （NPK）, green manure （Astragalus sinicus L.） in early rice only （OM1）, high rate of green manure in early rice only （OM2）, combined green manure in early rice and farmyard manure in late rice （OM3）, combined green manure in early rice, farmyard manure in late rice and rice straw mulching in winter （OM4）, combined green manure in early rice and rice straw mulching in winter （OMS）. Our data showed that the SOC content was the highest under OM3 and OM4, followed by OM1, OM2 and OM5, then NPK fertilization, and the lowest under non-fertilization. However, our analyses in SOC stock indicated a significant difference between OM3 （33.9 t ha^-1） and OM4 （31.8 t ha^-1）, but no difference between NPK fertilization （27 t ha^-1） and nonfertilization （28.1 t ha^-1）. There was a significant linear increase in SOC over time for all treatments, and the slop of linear equation was greater in organic manure treatments （0.276-0.344 g kg-1 yr^-1） than in chemical fertilizer （0.216 g kg^-1 yr^-1） and no fertilizer （0.127 g kg^-1 yr^-1）.展开更多
The application of hard/soft composite structure in personnel armor for blast mitigation is relatively practical and effective in realistic protection engineering,such as the shell/liner system of the helmet.However,t...The application of hard/soft composite structure in personnel armor for blast mitigation is relatively practical and effective in realistic protection engineering,such as the shell/liner system of the helmet.However,there is still lacking a reliable experi-mental methodology to effectively evaluate the blast mitigation performance when the structure directly contacts the protected target,which limits the development of protection structures.In this paper,we proposed a new method to evaluate experi-mentally and numerically the blast mitigation performance of hard/soft composite structures.The blast mitigation mechanism is analyzed.The hard/soft structures were composed of ultra-high molecular weight polyethylene(UHMWPE)composite and expanded polyethylene(EPE)foam.In field explosion experiment,a 7.0 kg trinitrotoluene(TNT)spherical charge is used to generate blast waves at a 3.8 m stand-off distance.A pressure test device is designed to support the tested structure and measure the transmitted blast pressure pulses after passing through the structure.Experimental results indicate that the hard/soft structures can mitigate the blast pressure pulse into the triangular pressure pulse,through making the pulse profile flatter,reducing the pressure amplitude,and delaying the pulse arrival time.Specifically,the combination of 7 mm UHMWPE composite and 20 mm EPE foam can reduce the blast pressure amplitude by 40%.Correspondingly,the finite element simulation is also carried out to understand the blast mitigation mechanism.The numerical results indicate that the regulation for blast pressure pulses mainly complete at the hard/soft interface,which is attributed to the reflection of pressure waves at the interface and the deformation of the soft layer compressed by the hard layer possessing kinetic energy.Furthermore,based on these analyses,the corresponding theoretical model is proposed,and it can well explain the experimental and numerical results.This study is meaningful for evaluating and designing high-performance blast mitigation structures.展开更多
Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model.The effect of pore air pressure on rainfall infiltration has been widely recogn...Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model.The effect of pore air pressure on rainfall infiltration has been widely recognized and validated by means of numerical simulations and laboratory experiments.However,whether a slope can actually seal pore air continues to be debated by researchers.In this study,a water-air two-phase flow model is used to simulate the rainfall infiltration process on a soil slope,and a field experiment is conducted to realistically test the sealing conditions of a slope.According to the numerical simulation,the areas of water and air flow in and out on the slope surface are relatively stable and can be classified as the“inhalation zone”and“overflow zone”,respectively.Intermittent rainfall on the soil slope has an amplifying effect on pore air pressure because rainfall intensity is usually at the millimeter level,and it causes pore air pressure to reach the cm level.A field experiment was performed to determine whether a slope can realistically seal pore air and subsequently verify the regularity of rainfall infiltration.Air pressure sensors were buried in the slope to monitor the pore air pressures during the rainfall process.The monitoring results show that the pore air pressure in the slope changed,which indicates that the slope can seal air.Moreover,the amplification effects of intermittent rainfall on pore air pressure were observed for natural rainfall,which agrees well with the numerical simulation results.展开更多
Iron-oxidizing strain(FeOB)and iron modified biochars have been shown arsenic(As)reme-diation ability in the environment.However,due to the complicated soil environment,few field experiment has been conducted.The stud...Iron-oxidizing strain(FeOB)and iron modified biochars have been shown arsenic(As)reme-diation ability in the environment.However,due to the complicated soil environment,few field experiment has been conducted.The study was conducted to investigate the potential of iron modified biochar(BC-FeOS)and biomineralization by a new found FeOB to remediate As-contaminated paddy field.Compared with the control,the As contents of G_(B)(BC-FeOS),G_(F)(FeOB),G_(FN)(FeOB and nitrogen fertilizer),G_(BF)(BC-FeOS and FeOB)and G_(BFN)(BC-FeOS,FeOB and nitrogen fertilizer)treatments in pore water decreased by 36.53%-80.03%and the microbial richness of iron-oxidizing bacteria in these treatments increased in soils at the rice maturation stage.The concentrations of available As of G_(B),G_(F),G_(FN),G_(BF) and G_(BFN) at the tillering stage were significantly decreased by 10.78%-55.48%.The concentrations of non-specifically absorbed and specifically absorbed As fractions of G_(B),G_(F),G_(FN),G_(BF) and G_(BFN) in soils were decreased and the amorphous and poorly crystalline hydrated Fe and Al oxidebound fraction was increased.Moreover,the As contents of G_(B),G_(F),G_(FN),G_(BF) and G_(BFN) in rice grains were significantly decreased(*P<0.05)and the total As contents of G_(FN),G_(BF) and G_(BFN) were lower than the standard limit of the National Standard for Food Safety(GB 2762-2017).Compared with the other treatments,G_(BFN) showed the greatest potential for the effective remediation of As-contaminated paddy fields.展开更多
Vegetation plays a key role in improving wind environment of residential districts,and is helpful for creating a comfortable and beautiful living environment.The optimal design of vegetation for wind environment impro...Vegetation plays a key role in improving wind environment of residential districts,and is helpful for creating a comfortable and beautiful living environment.The optimal design of vegetation for wind environment improvement in winter was investigated by carrying out field experiments in Heqingyuan residential area in Beijing,and after that,numerical simulation with SPOTE(simulation platform for outdoor thermal environment) experiments for outdoor thermal environment of vegetation was adopted for comparison.The conclusions were summarized as follows:1) By comparing the experimental data with simulation results,it could be concluded that the wind field simulated was consistent with the actual wind field,and the flow distribution impacted by vegetation could be accurately reflected;2) The wind velocity with vegetation was lower than that without vegetation,and the wind velocity was reduced by 46%;3) By adjusting arrangement and types of vegetation in the regions with excessively large wind velocity,the pedestrian-level wind velocity could be obviously improved through the simulation and comparison.展开更多
Aiming at the needs of mechanism analysis of rainstorms and development of numerical prediction models in south China, the Guangzhou Institute of Tropical and Marine Meteorology of China Meteorological Administration ...Aiming at the needs of mechanism analysis of rainstorms and development of numerical prediction models in south China, the Guangzhou Institute of Tropical and Marine Meteorology of China Meteorological Administration and the Chinese Academy of Meteorological Sciences jointly set up the Longmen Cloud Physics Field Experiment Base,China Meteorological Administration. This paper introduces the instruments and field experiments of this base, provides an overview of the recent advances in retrieval algorithms of microphysical parameters, improved understanding of microphysical characteristics, as well as the formation mechanisms and numerical prediction of heavy rainfalls in south China based on the field experiments dataset.展开更多
Microwave-assisted mechanical excavation has great application prospects in mines and tunnels,but there are few field experiments on microwave-assisted rock breaking.This paper takes the Sishanling iron mine as the re...Microwave-assisted mechanical excavation has great application prospects in mines and tunnels,but there are few field experiments on microwave-assisted rock breaking.This paper takes the Sishanling iron mine as the research object and adopts the self-developed high-power microwave-induced fracturing test system for hard rock to conduct field experiments of microwave-induced fracturing of iron ore.The heating and reflection evolution characteristics of ore under different microwave parameters(antenna type,power,and working distance)were studied,and the optimal microwave parameters were obtained.Subsequently,the ore was irradiated with the optimal microwave parameters,and the cracking effect of the ore under the action of the high-power open microwave was analyzed.The results show that the reflection coefficient(standing wave ratio)can be rapidly(<5 s)and automatically adjusted below the preset threshold value(1.6)as microwave irradiation is performed.When using a right-angle horn antenna with a working distance of 5 cm,the effect of automatic reflection adjustment reaches the best among other antenna types and working distances.When the working distance is the same,the average temperature of the irradiation surface and the area of the high-temperature area under the action of the two antennas(right-angled and equal-angled horn antenna)are basically the same and decrease with the increase of working distance.The optimal microwave parameters are:a right-angle horn antenna with a working distance of 5 cm.Subsequently,in further experiments,the optimal parameters were used to irradiate for 20 s and 40 s at a microwave power of 60 kW,respectively.The surface damage extended 38 cm×30 cm and 53 cm×30 cm,respectively,and the damage extended to a depth of about 50 cm.The drilling speed was increased by 56.2%and 66.5%,respectively,compared to the case when microwaves were not used.展开更多
Based on the blasting theory and stress wave theory, stemming mechanism and movement of stemmed material in rock blasting were analyzed and the calculation expression of stemming lengths was deduced. The blasting expe...Based on the blasting theory and stress wave theory, stemming mechanism and movement of stemmed material in rock blasting were analyzed and the calculation expression of stemming lengths was deduced. The blasting experiment with different stemming lengths was carried out and the results show that the theoretical stemming length, which is 0.73 ~ 0.8 time of burden, is in the range of the experiential length, which is O. 63 - O. 88 time of burden. The blasting results of field experiments with theoretical stemming length are satisfactory, which shows the theoretical derivation and analysis are correct and reliable. The results will supply rock blasting with the theoretical gist of parameters design.展开更多
In order to solve coal and gas outbursts during mining coal seam,studying on related problems were carried out. According to the theories of mining upper protective layer,proper mining plan were designed and performed...In order to solve coal and gas outbursts during mining coal seam,studying on related problems were carried out. According to the theories of mining upper protective layer,proper mining plan were designed and performed through field experiment. By means of examining several parameters obtained from the field experiment,the protective effects were evaluated and the protective scope and related parameters were determined. The results of field experiment show that the danger of outbursts was evidently eliminated and the method of mining protective layers is effective and the safety and economic benefits are remarkable. The research has really applied worth and will give beneficial references to mining area with analogous conditions.展开更多
A brief account of the development of the research on mining earthquakes and the general situation of the Mentougou Coal Mine medium scale experiment field for earthquake prediction and the project of monitor and p...A brief account of the development of the research on mining earthquakes and the general situation of the Mentougou Coal Mine medium scale experiment field for earthquake prediction and the project of monitor and prediction is given. The differences of waveforms between mining earthquakes and natural earthquakes is discussed. The magnitude frequency distribution of the 79 000 mining earthquakes of over M L1.0 from 1984 to 1995 is summarized . Finally, taking PH and PV, the principal compressive stress components of the focal mechanism of the mining earthquakes, as the criteria, analyses the stress background of the 12 large mining earthquakes.展开更多
Fish traps were investigated to understand the effects of season, bait type, trap size, and trap soak time on catch rates, catch composition, and trap loss rates from March 2004 to September 2005, to improve the perfo...Fish traps were investigated to understand the effects of season, bait type, trap size, and trap soak time on catch rates, catch composition, and trap loss rates from March 2004 to September 2005, to improve the performance and management of Kuwait＇s gargoor （cage style fish trap） fishery, which used to be the nation＇s most important one in terms of value and landings volume. Catch rates were the highest in April/May （5 8 kg/trap haul） and again in December （7 kg/trap haul）. Bait type and trap size also affected catch rates and species composition. Of the seven baits tested, the best catch rates, 〉5 kg/trap haul, occurred with cuttlefish （Sepia pharaonis）, but wolf-herring （Chiroeentrus dorab） and mullet （Liza klunzingeri） also produced good results （4-5 kg/trap haul）. Within the five tested sizes, the two largest-sized traps captured more fish and larger size fish. Analysis of variance （ANOVA） showed significant differences of catch rate among traps with different baits as well as among traps of different sizes. Duncan test further revealed these differences between two specific baits and sizes. Cluster Analysis of species composition showed more differences among different baits than among different trap sizes. Longer soak times did not result in larger catch rates, but increased trap loss. About 10-day soak time resulted in trap loss 7%, while 40-day soak time could result in a loss of around 20%. Consequently, it is recommended that the gargoor be checked every 10 or fewer days. The average overall catch rate during the study period was lower than that of 1980s （4.5 vs. 5.8 kg/trap haul）, indicating a possible decline offish abundance in Kuwait＇s waters. It is recommended that the number of gargoor fishing boats and gargoors from each boat should be limited to allow stock rehabilitation.展开更多
基金supported by the National Natural Science Foundation of China (No. 50539050)
文摘The downslope movement of detached rock blocks along steep slopes is an important process endangering the safety of infrastructure along the foot of a slope and on the valley bottom,but only limited knowledge is available on the influence of various factors on the velocity and distance of movement of such blocks.We discuss the influence of the mass and shape of the rock blocks,the steepness of the slope,and the thickness of the overburden on the slope,on the distance of movement of rock blocks which was observed in 256 field experiments with differently shaped blocks from 3 different positions on the slope with a height of 176 m.The statistical evaluation of the results of the field tests shows that the slope condition of gradient and overburden is the main factor,the form of rock masses is the second factor,and the mass is the third of the influencing factors.It is the maximum average acceleration for movement of rock masses when the mass of rock masses is 15≤m27 kg,the form of rock masses is flake,the condition of gradient is on average 59.6° and the overburden is basic exposed bedrock and a small quantity of gravel-soil in the experiment condition.It is the minimum average acceleration for movement of rock masses when the mass of rock masses is 9.5≤m15 kg,the form of rock masses is rectangular,the condition of gradient is on average 39° and the overburden is gravel-soil and cinder.Then,the foundation for impact energy is provided and the new feasible methods to prevent potential unstable rock masses are put forward.
文摘Late blight caused by <i>Phytophthora</i> <i>infestans</i> (Mont.) De Bary is the most devastating disease of potato. This study was carried out to evaluate the efficacy of ten botanical extracts against the late blight disease incidence and severity in experimental potato field at University of Rajshahi, Bangladesh during 2019-2020. Crude aqueous extract of leaves of <i>Syzygium</i> <i>cumini</i>, <i>Psidium</i> <i>guajava</i>, <i>Eucalyptus</i> <i>globusus</i>, <i>Carica</i> <i>papaya</i> and <i>Lawsonia</i> <i>inermis</i>;fruits of <i>Terminalia</i> <i>bellirica</i>, <i>T.</i> <i>chebula</i> and <i>Piper</i> <i>nigrum</i>;flower buds of <i>Syzygium</i> <i>aromaticum</i> and cloves of <i>Allium</i> <i>sativum</i> were used at 5% (w/v) concentration for evaluation. Out of ten botanicals, <i>Syzygium</i> <i>cumini</i> leaves extract was found most effective in controlling the late blight disease incidence and severity up to 66 DAS (days after sowing) and increased the potato yield by 71.29% compare to untreated control. The efficacy of <i>Lawsonia</i> <i>inermis</i> extract against late blight disease was found promising and increased the potato yield by 48.51%. Other four botanical extracts (<i>Terminalia</i> <i>chebula</i>, <i>Piper</i> <i>nigrum</i>, <i>Syzygium</i> <i>aromaticum</i> and <i>Carica</i> <i>papaya</i>) showed moderate efficacy <span>against the incidence and severity of late blight disease, and increased 30% </span>more potato yield compare to control. These results suggest that botanical extract of <i>Syzygium</i> <i>cumini</i> ha<span style="font-family:;" "="">s</span><span style="font-family:;" "=""> a great potential as an alternative </span><span style="font-family:;" "="">of</span><span style="font-family:;" "=""> chemical fungicides to control the late blight disease of potato in</span><span style="font-family:;" "=""> </span><span style="font-family:;" "="">eco-friendly way.</span>
基金Supported by the Beijing Natural Science Foundation under Grant No 4133086the Fundamental Research Funds for th Central Universities under Grant No 2-9-2014-022
文摘We propose optical experiments to study the depth of field for a thermal light lensless ghost imaging system. It is proved that the diaphragm is an important factor to influence the depth of field, and the ghost images of two detected objects with longitudinal distance less than the depth of field can be achieved simultaneously. The longitudinal coherence scale of the thermal light lensless ghost imaging determines the depth of field. Theoretical analysis can well explain the experimental results.
文摘In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high identification to discontinuity are used to the numerical reconstruction of part of an actual hemispherical blast-wave flow field by properly adjusting the moving bounary conditions of a piston. This method is simple and reliable. It is suitable to the evaluation of effects of the blast-wave flow field away from the explosion center.
基金funded by grants from Shandong Second Medical University’s School-level Education and Teaching Reform and Research Projects(2024YB005,2024YB041,2024YB028)the Ministry of Education’s University-Industry Collaborative Education Program(2408074631)+1 种基金the China Association of Higher Education’s 2022 Annual Higher Education Scientific Research Planning Project(22SX0419)its 2024 Key Project of Annual Higher Education Scientific Research Planning Project(24YZ0205).
文摘Amid the deepening global higher education reforms,developing innovative teaching models to enhance student academic performance and satisfaction has become a crucial research priority.This study uses a field experiment to evaluate the impact of the industry-university-research collaborative teaching(IURCT)model on students’performance and satisfaction.Comparing the Learning Assessment Score(LAS)and Satisfaction Score(SS)of the IURCT model with those of the traditional teaching methods,the experimental results showed that both LAS and SS were significantly higher for students in the IURCT model,and the effects continued to strengthen over the intervention period.Mechanism tests reveal that the IURCT model enhances the LAS and SS by boosting learning motivation,providing personalized support,and offering psychological support.Furthermore,heterogeneity analysis indicates that the IURCT model’s vary across gender,region,and academic levels.This study provides empirical support for the application of the IURCT model in education and offers valuable insights for policymakers to optimize teaching models.
基金supported in part by National Natural Science Foundation of China under Grant 62201087,Grant 62525101,in part by the National Key R&D Program of China under Grant 2023YFB2904803in part by the Guangdong Major Project of Basic and Applied Basic Research under Grant 2023B0303000001+1 种基金in part by the Natural Science Foundation of Beijing-Xiaomi Innovation Joint Foundation under Grant L243002in part by the Beijing University of Posts and Telecommunications-China Mobile Research Institute Joint Institute.
文摘As the commercialization of the fifth gen-eration communication(5G)is sped up,its system testing scheme is vital for the successful deployment of 5G.Especially,5G relies on the scale-increased multiple-input-multiple output(MIMO)technique to improve its capacity and coverage.Thus,testing new functions of the 5G MIMO system accurately and ef-ficiently,including beamforming(beam-tracking with movement)and multiple-user(MU)multiplexing,is a challenging task.This paper tries to construct a lab-oratorial hardware and conduct equipment-controlled field testing.Firstly,the testing scheme is presented,which is composed of the framework,the channel models and the validation methods.Then,the channel model principles are explained in detail due to its di-rect influence on the testing accuracy.Specifically,we utilize the spatial consistency and the multi-link cor-relation properties to emulate the high-speed dynamic time-varying(HDT)and the multiple-cell(MC)-MU-MIMO channels.Finally,the above testing scheme is verified in a Shanghai 5G field experiment with the practical commercial equipment and the channel em-ulator.The results show that the 5G new functions are tested accurately and efficiently by switching the channel emulation configurations.
文摘[Objective] The aim was to study the effect of three new fungicides against rice sheath blight in field experiment. [Methods] The experiment set up 7 treatments with three times of repetition and designed by random grouping. By using 5 sampling points in each plot, and investigating continuous 4 holes of each point, total plants, diseased plants and disease degrees were recorded. Then disease index and control efficiency were calculated, and variance analysis was carried out. [Results] 300 or 450 ml/hm^2 azoxystrobin ＋ difenoconazole 325 g/L SC had better control efficiency to rice sheath blight and had no phytotoxicity effect, we should use it at the initial disease stage and continuously spray 2-3 times. [Conclusion] The experiment provided a theoretical basis for controlling rice sheath blight using fungicides.
基金National Natural Science Foundation of China Under Grant No. 50538010Natural Science Foundation of Beijing Under Grant No. 8082021the Flander (Belgium)-China Bilateral Project Under Grant No. BIL07/07
文摘In this paper, a field experiment was carried out to study train-induced environmental vibrations. During the field experiment, velocity responses were measured at different locations of a six-story masonry structure near the Beijing- Guangzhou Railway and along a small road adjacent to the building. The results show that the velocity response levels of the environmental ground and the building floors increase with train speed, and attenuate with the distance to the railway track. Heavier freight trains induce greater vibrations than lighter passenger trains. In the multi-story building, the lateral velocity levels increase monotonically with floor elevation, while the vertical ones increase with floor elevation in a fluctuating manner. The indoor floor vibrations are much lower than the outdoor ground vibrations. The lateral vibration of the building along the direction of weak structural stiffness is greater than along the direction with stronger stiffness. A larger room produces greater floor vibrations than the staircase at the same elevation, and the vibration at the center of a room is greater than at its corner. The vibrations of the building were compared with the Federal Transportation Railroad Administration （FTA） criteria for acceptable ground-borne vibrations expressed in terms ofrms velocity levels in decibels. The results show that the train-induced building vibrations are serious, and some exceed the allowance given in relevant criterion.
基金supported by the Special Fund for Agroscientific Research in the Public Interest (201203030 and 201003016)the National Basic Research Program of China (973 Program, 2011CB100501-S06)the National Natural Science Foundation of China (41301269)
文摘Soil organic carbon （SOC） is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields because of their vest expansion in south China. A study was carried out to evaluate the relationship between the SOC content and organic carbon input under various organic amendments at a long-term fertilization experiment that was established on a red soil under a double rice cropping system in 1981. The treatments included non-fertilization （CK）, nitrogen-phosphorus-potassium fertilization in early rice only （NPK）, green manure （Astragalus sinicus L.） in early rice only （OM1）, high rate of green manure in early rice only （OM2）, combined green manure in early rice and farmyard manure in late rice （OM3）, combined green manure in early rice, farmyard manure in late rice and rice straw mulching in winter （OM4）, combined green manure in early rice and rice straw mulching in winter （OMS）. Our data showed that the SOC content was the highest under OM3 and OM4, followed by OM1, OM2 and OM5, then NPK fertilization, and the lowest under non-fertilization. However, our analyses in SOC stock indicated a significant difference between OM3 （33.9 t ha^-1） and OM4 （31.8 t ha^-1）, but no difference between NPK fertilization （27 t ha^-1） and nonfertilization （28.1 t ha^-1）. There was a significant linear increase in SOC over time for all treatments, and the slop of linear equation was greater in organic manure treatments （0.276-0.344 g kg-1 yr^-1） than in chemical fertilizer （0.216 g kg^-1 yr^-1） and no fertilizer （0.127 g kg^-1 yr^-1）.
基金the Science Challenge Project(Grant No.TZ2018002)the National Natural Science Foundation of China(Grant Nos.11972205 and 11722218)+1 种基金the National Key Research Development Program of China(Grant No.2017YFB0702003)Opening Project of Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province.
文摘The application of hard/soft composite structure in personnel armor for blast mitigation is relatively practical and effective in realistic protection engineering,such as the shell/liner system of the helmet.However,there is still lacking a reliable experi-mental methodology to effectively evaluate the blast mitigation performance when the structure directly contacts the protected target,which limits the development of protection structures.In this paper,we proposed a new method to evaluate experi-mentally and numerically the blast mitigation performance of hard/soft composite structures.The blast mitigation mechanism is analyzed.The hard/soft structures were composed of ultra-high molecular weight polyethylene(UHMWPE)composite and expanded polyethylene(EPE)foam.In field explosion experiment,a 7.0 kg trinitrotoluene(TNT)spherical charge is used to generate blast waves at a 3.8 m stand-off distance.A pressure test device is designed to support the tested structure and measure the transmitted blast pressure pulses after passing through the structure.Experimental results indicate that the hard/soft structures can mitigate the blast pressure pulse into the triangular pressure pulse,through making the pulse profile flatter,reducing the pressure amplitude,and delaying the pulse arrival time.Specifically,the combination of 7 mm UHMWPE composite and 20 mm EPE foam can reduce the blast pressure amplitude by 40%.Correspondingly,the finite element simulation is also carried out to understand the blast mitigation mechanism.The numerical results indicate that the regulation for blast pressure pulses mainly complete at the hard/soft interface,which is attributed to the reflection of pressure waves at the interface and the deformation of the soft layer compressed by the hard layer possessing kinetic energy.Furthermore,based on these analyses,the corresponding theoretical model is proposed,and it can well explain the experimental and numerical results.This study is meaningful for evaluating and designing high-performance blast mitigation structures.
基金sponsored by The National Natural Science Foundation of China(Grant Nos.51939004 and 51279090)The National Key Research and Development Program of China(2017YFC1501100)the Hubei Key Laboratory of Construction and Management in Hydropower Engineering(2020KSD11).
文摘Rainfall infiltration on a soil slope is usually an unsaturated seepage process that can be described by a water-air two-phase flow model.The effect of pore air pressure on rainfall infiltration has been widely recognized and validated by means of numerical simulations and laboratory experiments.However,whether a slope can actually seal pore air continues to be debated by researchers.In this study,a water-air two-phase flow model is used to simulate the rainfall infiltration process on a soil slope,and a field experiment is conducted to realistically test the sealing conditions of a slope.According to the numerical simulation,the areas of water and air flow in and out on the slope surface are relatively stable and can be classified as the“inhalation zone”and“overflow zone”,respectively.Intermittent rainfall on the soil slope has an amplifying effect on pore air pressure because rainfall intensity is usually at the millimeter level,and it causes pore air pressure to reach the cm level.A field experiment was performed to determine whether a slope can realistically seal pore air and subsequently verify the regularity of rainfall infiltration.Air pressure sensors were buried in the slope to monitor the pore air pressures during the rainfall process.The monitoring results show that the pore air pressure in the slope changed,which indicates that the slope can seal air.Moreover,the amplification effects of intermittent rainfall on pore air pressure were observed for natural rainfall,which agrees well with the numerical simulation results.
基金This work was supported by the National Natural Science Foundation of China(No.41771512)the Dean’s Research Fund 2020/21(Project code:04626)of the Education University of Hong Kong.
文摘Iron-oxidizing strain(FeOB)and iron modified biochars have been shown arsenic(As)reme-diation ability in the environment.However,due to the complicated soil environment,few field experiment has been conducted.The study was conducted to investigate the potential of iron modified biochar(BC-FeOS)and biomineralization by a new found FeOB to remediate As-contaminated paddy field.Compared with the control,the As contents of G_(B)(BC-FeOS),G_(F)(FeOB),G_(FN)(FeOB and nitrogen fertilizer),G_(BF)(BC-FeOS and FeOB)and G_(BFN)(BC-FeOS,FeOB and nitrogen fertilizer)treatments in pore water decreased by 36.53%-80.03%and the microbial richness of iron-oxidizing bacteria in these treatments increased in soils at the rice maturation stage.The concentrations of available As of G_(B),G_(F),G_(FN),G_(BF) and G_(BFN) at the tillering stage were significantly decreased by 10.78%-55.48%.The concentrations of non-specifically absorbed and specifically absorbed As fractions of G_(B),G_(F),G_(FN),G_(BF) and G_(BFN) in soils were decreased and the amorphous and poorly crystalline hydrated Fe and Al oxidebound fraction was increased.Moreover,the As contents of G_(B),G_(F),G_(FN),G_(BF) and G_(BFN) in rice grains were significantly decreased(*P<0.05)and the total As contents of G_(FN),G_(BF) and G_(BFN) were lower than the standard limit of the National Standard for Food Safety(GB 2762-2017).Compared with the other treatments,G_(BFN) showed the greatest potential for the effective remediation of As-contaminated paddy fields.
基金Project(50878111) supported by the National Natural Science Foundation of China
文摘Vegetation plays a key role in improving wind environment of residential districts,and is helpful for creating a comfortable and beautiful living environment.The optimal design of vegetation for wind environment improvement in winter was investigated by carrying out field experiments in Heqingyuan residential area in Beijing,and after that,numerical simulation with SPOTE(simulation platform for outdoor thermal environment) experiments for outdoor thermal environment of vegetation was adopted for comparison.The conclusions were summarized as follows:1) By comparing the experimental data with simulation results,it could be concluded that the wind field simulated was consistent with the actual wind field,and the flow distribution impacted by vegetation could be accurately reflected;2) The wind velocity with vegetation was lower than that without vegetation,and the wind velocity was reduced by 46%;3) By adjusting arrangement and types of vegetation in the regions with excessively large wind velocity,the pedestrian-level wind velocity could be obviously improved through the simulation and comparison.
基金National Natural Science Foundation of China(U22422203,42030610,41975138,41975046,42075086,42275008)the High-level Science and Technology Journals Projects of Guangdong Province(214040990009)+1 种基金National Key Research and Development Program of China under Grant(2017YFC1501701,2017YFC1501703)Science and Technology Foundation of CAMS(2020KJ021)。
文摘Aiming at the needs of mechanism analysis of rainstorms and development of numerical prediction models in south China, the Guangzhou Institute of Tropical and Marine Meteorology of China Meteorological Administration and the Chinese Academy of Meteorological Sciences jointly set up the Longmen Cloud Physics Field Experiment Base,China Meteorological Administration. This paper introduces the instruments and field experiments of this base, provides an overview of the recent advances in retrieval algorithms of microphysical parameters, improved understanding of microphysical characteristics, as well as the formation mechanisms and numerical prediction of heavy rainfalls in south China based on the field experiments dataset.
基金financial support from the National Natural Science Foundation of China(Grant No.41827806)the Liaoning Provincial Science and Technology Program of China(Grant No.2022JH2/101300109).
文摘Microwave-assisted mechanical excavation has great application prospects in mines and tunnels,but there are few field experiments on microwave-assisted rock breaking.This paper takes the Sishanling iron mine as the research object and adopts the self-developed high-power microwave-induced fracturing test system for hard rock to conduct field experiments of microwave-induced fracturing of iron ore.The heating and reflection evolution characteristics of ore under different microwave parameters(antenna type,power,and working distance)were studied,and the optimal microwave parameters were obtained.Subsequently,the ore was irradiated with the optimal microwave parameters,and the cracking effect of the ore under the action of the high-power open microwave was analyzed.The results show that the reflection coefficient(standing wave ratio)can be rapidly(<5 s)and automatically adjusted below the preset threshold value(1.6)as microwave irradiation is performed.When using a right-angle horn antenna with a working distance of 5 cm,the effect of automatic reflection adjustment reaches the best among other antenna types and working distances.When the working distance is the same,the average temperature of the irradiation surface and the area of the high-temperature area under the action of the two antennas(right-angled and equal-angled horn antenna)are basically the same and decrease with the increase of working distance.The optimal microwave parameters are:a right-angle horn antenna with a working distance of 5 cm.Subsequently,in further experiments,the optimal parameters were used to irradiate for 20 s and 40 s at a microwave power of 60 kW,respectively.The surface damage extended 38 cm×30 cm and 53 cm×30 cm,respectively,and the damage extended to a depth of about 50 cm.The drilling speed was increased by 56.2%and 66.5%,respectively,compared to the case when microwaves were not used.
文摘Based on the blasting theory and stress wave theory, stemming mechanism and movement of stemmed material in rock blasting were analyzed and the calculation expression of stemming lengths was deduced. The blasting experiment with different stemming lengths was carried out and the results show that the theoretical stemming length, which is 0.73 ~ 0.8 time of burden, is in the range of the experiential length, which is O. 63 - O. 88 time of burden. The blasting results of field experiments with theoretical stemming length are satisfactory, which shows the theoretical derivation and analysis are correct and reliable. The results will supply rock blasting with the theoretical gist of parameters design.
文摘In order to solve coal and gas outbursts during mining coal seam,studying on related problems were carried out. According to the theories of mining upper protective layer,proper mining plan were designed and performed through field experiment. By means of examining several parameters obtained from the field experiment,the protective effects were evaluated and the protective scope and related parameters were determined. The results of field experiment show that the danger of outbursts was evidently eliminated and the method of mining protective layers is effective and the safety and economic benefits are remarkable. The research has really applied worth and will give beneficial references to mining area with analogous conditions.
文摘A brief account of the development of the research on mining earthquakes and the general situation of the Mentougou Coal Mine medium scale experiment field for earthquake prediction and the project of monitor and prediction is given. The differences of waveforms between mining earthquakes and natural earthquakes is discussed. The magnitude frequency distribution of the 79 000 mining earthquakes of over M L1.0 from 1984 to 1995 is summarized . Finally, taking PH and PV, the principal compressive stress components of the focal mechanism of the mining earthquakes, as the criteria, analyses the stress background of the 12 large mining earthquakes.
基金Supported by the Kuwait Foundation for the Advancement of Science (KFAS)the Public Authority for Agriculture and Fisheries Resources(PAAFR)+1 种基金the Project of Investigation to Improve Kuwait’s Demersal Trap Fishery of Kuwait Institute for Scientific Research (KISR)which was conducted at the Mariculture and Fisheries Department of KISR
文摘Fish traps were investigated to understand the effects of season, bait type, trap size, and trap soak time on catch rates, catch composition, and trap loss rates from March 2004 to September 2005, to improve the performance and management of Kuwait＇s gargoor （cage style fish trap） fishery, which used to be the nation＇s most important one in terms of value and landings volume. Catch rates were the highest in April/May （5 8 kg/trap haul） and again in December （7 kg/trap haul）. Bait type and trap size also affected catch rates and species composition. Of the seven baits tested, the best catch rates, 〉5 kg/trap haul, occurred with cuttlefish （Sepia pharaonis）, but wolf-herring （Chiroeentrus dorab） and mullet （Liza klunzingeri） also produced good results （4-5 kg/trap haul）. Within the five tested sizes, the two largest-sized traps captured more fish and larger size fish. Analysis of variance （ANOVA） showed significant differences of catch rate among traps with different baits as well as among traps of different sizes. Duncan test further revealed these differences between two specific baits and sizes. Cluster Analysis of species composition showed more differences among different baits than among different trap sizes. Longer soak times did not result in larger catch rates, but increased trap loss. About 10-day soak time resulted in trap loss 7%, while 40-day soak time could result in a loss of around 20%. Consequently, it is recommended that the gargoor be checked every 10 or fewer days. The average overall catch rate during the study period was lower than that of 1980s （4.5 vs. 5.8 kg/trap haul）, indicating a possible decline offish abundance in Kuwait＇s waters. It is recommended that the number of gargoor fishing boats and gargoors from each boat should be limited to allow stock rehabilitation.
