Development of a Depth Control System Based on Variable-Gain Single-Neuron PID for Rotary Burying of Stubbles

Rotary burying by tractor-hitched rotary tillers is a common practice in southern China for treating rice stubbles. Currently, it is difficult to maintain stable tillage depths due to surface unevenness and the residual stubbles in the field, which leads to unstable tillage quality and nonuniform crop growth in later stages. In this study, an RTK-GNSS was used to measure the real-time height and roll angle of the tractor, and a variable-gain single-neuron PID control algorithm was designed to adjust the coefficients (KP, KI, and KD) and gain K in real-time according to the control effects. An on-board computer sent the angles of the upper swing arm u(t) to an STM32 microcontroller through a CAN bus. Compared with the current angle of the upper swing arm, the microcontroller controlled an electronic-control proportional hydraulic system, so that the height of the rotary tiller could be adjusted to follow the field undulations in real-time. Field experiments showed that when the operation speed of the tractor-rotary tiller system was about 0.61 m/s, the variable-gain single-neuron PID algorithm could effectively improve the stability of the working depth and the stubbles’ burying rate. Compared with a conventional PID controller, the stability coefficient and the stubbles’ burying rate were improved by 5.85% and 4.38%, respectively, and compared with a single-neuron PID controller, the stability coefficient and the stubbles’ burying rate were improved by 4.37% and 3.49%, respectively. This work controlled the working depth of the rotary tiller following the changes in the field surface in real-time and improved the stubbles’ burying rate, which is suitable for the unmanned operation of the rotary burying of stubbles in the future.

Upper Bound Analysis of the Stability of 3D Slopes in the Saturated Soft Clay Subjected to Seismic Effect

In order to study the three-dimensional stability problem of the saturated soft clay slope under earthquake loads, based on the three-dimensional rotation failure model, the seismic force was introduced into the calculation by the quasi-static method. The work rate of external loads and the internal energy dissipation rate of the saturated soft clay slope were calculated using the upper bound method of limit analysis, and the analytical solution of stability coefficient of saturated soft clay slopes was derived based on the fictitious power principle. By virtue of the exhaust algorithm, the optimal solution of stability coefficient of saturated soft clay slopes was obtained. The influence of the slope angle and the horizontal and vertical seismic forces on the stability coefficient of saturated soft clay slope was analyzed. The results show that the slope angle has a great influence on the stability coefficient, and the relative difference is up to 35.7%. Therefore, the stability coefficient of saturated soft clay slopes can be effectively increased by a proper slope setting. The horizontal and vertical seismic forces also have a significant influence on the stability of saturated soft clay slopes. The relative differences of the stability coefficient under horizontal and vertical seismic forces are as high as 41 and 14.7%, respectively. If they are ignored, the stability coefficient of saturated soft clay slopes will be seriously overestimated. It is suggested that the effects of horizontal and vertical seismic forces must be considered simultaneously in the seismic design of saturated soft clay slopes.

Analysis and Calculation of Stability Coefficients of Cross-Laminated Timber Axial Compression Member

Cross-laminated timber (CLT) elements are becoming increasingly popular in multi-storey timber-based structures, which have long been built in many different countries. Various challenges are connected with constructions of this type. One such challenge is that of stabilizing the structure against vertical loads. However, the calculations of the stability bearing capacity of the CLT members in axial compression in the structural design remains unsolved in China. This study aims to determine the stability bearing capacity of the CLT members in axial compression and to propose the calculation method of the stability coefficient. First, the stability coefficient calculation theories in different national standards were analyzed, and then the stability bearing capacity of CLT elements with four slenderness ratios was investigated. Finally, based on the stability coefficient calculation formulae in the GB 50005-2017 standard and the regression method, the calculation method of the stability coefficient for CLT elements was proposed, and the values of the material parameters were determined. The result shows that the average deviation between fitting curve and calculated results of European and American standard is 5.43% and 3.73%, respectively, and the average deviation between the fitting curve and the actual test results was 8.15%. The stability coefficients calculation formulae could be used to predict the stability coefficients of CLT specimens with different slenderness ratios well.

Earthquake Dynamic Failure Mechanism of Dangerous Rock Based on Dynamics and PFC3D

The dynamic failure mechanism of horizontally layered dangerous rock during earthquakes is complex and only few studies have addressed the combination of particle flow code (PFC) meso-level failure mechanism and mechanical analysis. Based on fracture mechanics and material mechanics we establish a calculation method for the interlayer load and stability coefficient of horizontal layered dangerous rock during strong earthquakes. The method was applied for calculating the stability of a horizontally layered dangerous slope along a highway in the Sichuan Province (China) during earthquakes as a case study. Using a 3D particle flow simulation technology, a PFC3D model of horizontal layered dangerous rock was established. Its dynamic stability, failure mode and Hilbert-Huang 3D time-frequency characteristics are analyzed, and the results of the simulation are largely consistent with the time of the dangerous rock failure as estimated by our new calculation method. Our study documents that as the seismic acceleration gradually increases, the stability coefficient of the rock block fluctuates more violently and the stability coefficient gradually decreases. The stability coefficient of the rock block decreases fastest between 5 and 6 s and the reduction in the stability coefficient is between 0.12 and 0.25. Before the seismic acceleration reaches the maximum, the dangerous rock blocks on the two main controlling structures collapse and get destroyed. 25 s after the earthquake, the failure mode of the dangerous rock is collapse-slip-rotation. We show that earthquakes with frequencies of 0–10 and 250 Hz have the strongest destructive effect on the stability of the horizontally layered dangerous rocks.

The Level of Morale Among Teachers of Learning Disabilities in English Language in Irbid, Jordan

This study aimed at identifying the degree of morale among teachers of learning disabilities in English language in Irbid governorate from the teachers' point of view. The study used the descriptive approach and developed a questionnaire as an instrument of the study. The study sample included (30) male and female teachers. The questionnaire was administered to the sample after verifying its validity and reliability. The instrument's stability coefficient was (95%). The results of the study showed that the teachers' morale levels were moderate. The study recommended providing more training and incentives to teachers to boost their morale, which will have an impact on their performance

Analysis of biology books for the preparatory stage in the light of biological security in the Republic of Iraq

The aim of the research is to analyze biology books for middle school in the light of biological security. From (3) main areas (health security, environmental security and food security) from which (50) sub-paragraphs emerged, then the researcher analyzed the biology books for the preparatory stage scheduled for the academic year (2020-2021) in the light of this criterion, as the number of analyzed pages reached (657) page. The registration and repetition units were adopted as a census unit, and the Holste equation was used to calculate the stability coefficient of the analysis in agreement with external analysts and with the researcher himself over time. Keywords : Biosecurity , biology books for middle school.

EFFECT OF DITCHING'S PARAMETERS ON OPERATION QUALITY OF ORCHARD DITCHING-FERTILIZER MACHINE

This study aims to evaluate the effects of different parameter settings on the ditching performance using a ditching-fertilizer. We aimed to improve the performance of ditching-fertilizer machine performance in sustainable agriculture. With Box-Behnken experimental design method, taking forward speed, the rotation speed of the ditching cutter, and the deflection angle of ditching cutter as experimental factors, taking ditching depth stability and soil coverage rate as test indexes, the operation parameters of orchard ditching-fertilizer machine are studied. The regression model between test indexes and experimental factors is established, and the influence of each factor on the experimental indexes is analyzed. The test factors are comprehensively optimized. The results show that when the forward speed is 0.8km/h, the rotation speed of the ditching cutter is 348r/min, and the deflection angle of the ditching cutter is 32°, the ditching effect is the best. At this time, the stability coefficient of the ditching depth is 98.33%, and the soil coverage rate is 81.53%. As for the field test, which measured the stability coefficient of ditching depth, and the average soil cover rate is 96.24%, and 79.14%, respectively, and the relative errors from the optimized value are 2.17%, and 3.02%, respectively.

Study on Ground Collapse of Covered Karst Soil Caves by Sudden Drop of Groundwater

In this study, the ellipsoidal soil cave with vertical collapses in the covering karst area is studied. Based on certain assumptions, the mechanical model of karst collapse caused by groundwater drop was established. Then, based on the negative pressure calculation formula of soil cave cavity according to Boyle–Mariotte’s law, the expression of the stability coefficient of the soil cave was proposed. Subsequently, the feasibility of the theoretical formula was verified. The calculation example analyzed the relationship of groundwater parameters and overburden thickness. The results show that when the initial groundwater level is higher than the top of cave, the law between the stability coefficient of soil cave and groundwater drawdown shows the jumping horizontal broken line. Thus, soil cave tends to collapse when the falling groundwater level drops over the vault; when the initial groundwater level ranges from the bottom to the top of the cave body, the stability coefficient and groundwater drawdown show a negative correlation law, the curve is steep at the early stage and then becomes gentle at the latter stage, and the higher the initial groundwater level in the cave is, the greater stability coefficient of soil cave reduces; when the initial groundwater level is lower than the bottom of the cave, the effect of drawdown is limited. In addition, for the small drawdown or low initial groundwater level, the stability coefficient of soil cave first decreases and then increases with the increases in thickness of overburden, and the thinner the overburden is, the greater the drawdown rate is; when the drawdown or the initial groundwater level is higher, the stability coefficient of soil cave positively relates to the thickness of the overburden layer.

Design and Experimental Research on Soil Covering Device with Linkage and Differential Adjustment of Potato Planter

When the potato planter works on sloping field, it will cause problems such as poor film mulching quality due to the difference in volume of soil covering both sides of the discs and the inconvenient adjustment of the soil covering disc. The soil covering device with linkage and differential adjustment was designed to improve the mulching quality. The main research content includes explaining the structure and principle of the soil covering device and analyzing the structural parameters of the adjustment mechanism. The field experiment was completed to verify the performance of soil covering device, which takes the stability coefficient and uniformity coefficient of the volume of covering soil as factors. The result shows the following: (1) The volume of covering soil changes exponentially with the angle of the disc through data fitting, which can standardize the angle of covering disc; and (2) when the angle of disc is 30° and 60°, respectively, the uniformity coefficient of volume of covering soil is lower than 1.4, which has premium soil covering quality. When the angles of the discs on both sides differ greatly, the stability coefficient of volume of covering soil is 0.41, which can meet the requirements of the mulching quality of potato planter. This research provides the technical support for high-quality potato planting.

Definition of Construction Parameters of Discrete Restraining Constructions

Purpose. There are many problems in the design of anti-landslide constructions, therefore discrete constructions are an alternative to solid anti-landslides. Despite the advantages of such constructions, difficulties also arise when using them. In this work, it is envisaged to develop methods for determining the zone of influence of discrete restraining constructions on the interaction of a sliding soil mass with them and a method for assessing the conditions of a stable state of the soil, which interacts with discrete restraining constructions, by constructing analytical dependencies necessary to determine the zone size and the soil stability coefficient. Methodology. Theoretical studies of geomechanical processes using analytical and numerical mathematical methods, as well as analysis and generalization of theoretical research results were used to achieve the purpose. Findings. The research results presented in the work allow, during the design of landslide discrete constructions, to determine the area of interaction of the shear with discrete retaining constructions, as well as to take into account the stability coefficient of the soil laid between the elements of the discrete retaining structure. Dependences were obtained for determining the zone size in which the sliding soil mass interacts, with discrete retaining constructions, and the soil stability coefficient in the zone of its interaction with these constructions. Originality. Analytical dependencies allow to calculate the boom of lifting the soil dumping arch between the elements of the discrete anti-landslide restraining construction and the coefficient of soil stability. Practical value. The research results allow, when designing discrete restraining constructions, to determine the area of interaction of the shear with these constructions and the stability coefficient of the soil laid between the elements of the discrete restraining construction.