Predicting soil fragmentation during tillage operation using fuzzy logic approach

One of the main characteristics of the soil structure, which affects the plant growth and its yield, is its aggregates size. Correct tillage operations leads to prevention from soil degradation and help to maintain and improve its physical, chemical, and biological characteristics. In this paper, a model based on fuzzy logic approach was used to describe the soil fragmentation for seedbed preparation in the composition of primary and secondary tillage implements of subsoiler, moldboard plow and disk harrow as conventional tillage composition in the region. Field experiments were carried out at educational and research farms of faculty of agriculture, University of Mohaghegh Ardabili. In this paper, an intelligent model, based on Mamdani approach fuzzy modeling principles, was developed to predict soil fragmentation during tillage operation. The model inputs included soil moisture content, tractor forward speed and soil sampling depth. The fuzzy model consisted of 50 rules, in which three parameters of root mean square error (RMSE), relative error (ɛ), and coefficient of determination (R²) were used to evaluate the fuzzy model. These parameters were calculated 0.167%, 3.95%, and 0.988%, respectively. According to the results of this research, the fuzzy model can be introduced as one of the methods for predicting soil fragmentation during the tillage operation with high accuracy.     

自钻式旁压试验推求土性参数的研究进展

自钻式旁压试验(SBPT)因其具有扰动小,能同时测量土体应力、应变及孔隙水压力的变化,在确定地基土性参数上有广阔的应用前景,成为岩土工程测试中利用率最高的原位测试手段之一。由于试验挤土过程与孔扩张过程具有很好的相似性,故多采用柱形孔扩张理论对旁压试验机理进行分析。本文详细阐述了SBPT力学机理分析的难点及假设条件适用性,并以Yu一文为基础,总结了SBPT推求土性参数及本构模型参数的理论分析方法、土性参数估测的误差来源与误差修正研究,为SBPT在国内广泛应用提供理论参考,最后对SBPT的机理解释及应用研究趋势进行了讨论。     

Recoil from elongation using general network models

In this paper, we use two new models and the irreversible KBKZ model of Wagner (Rheol Acta 18:681–692, 1979) to describe the famous experiments of Meissner (Rheol Acta 10:230–242, 1971) on the recoil of polyethylene. The new models are based both on network and reptation-type ideas. One of the new models (PTT-X) is a member of the PTT family and shows good agreement with polyethylene data in shearing, elongation, and recoil from elongation.     

Theoretical and experimental investigation of ultrasonic waves radiated from a wet surface using a line-focused laser beam

In this paper we use with a theoretical model and experimental study to predict the characteristics of the ultrasonic waves irradiated from a wet surface illuminated by a line-focused laser beam. The theoretical model is developed by assuming normal surface tractions distributed elliptically over the illuminated source. The solutions for both longitudinal and shear waves are obtained using Fourier analysis, in which the transform integral is evaluated asymptotically. The theory was evidenced by the experimental study which allows direct quantitative comparisons between the theoretical and experimental directivity patterns. The effects of beam diameter and frequency of the propagating wave, which are the most influential parameters on the characteristics of the generated wave, are investigated in the experimental work. The experimental results are in strong agreement with the theoretical predictions.