与套配机拉拖的柴油机质量问题

与套配机拉拖的柴油机质量问题国家中小拖拉机质检中心尹秉南国家中小拖拉机质检中心于１９９５年和１９９６年对中小轮式拖拉机及配套动力进行了两次产品质量国家监督抽查，检测不合格项目详见表１、２。现就抽查中发现的柴油机质量问题概要分析如下。１、可靠性差柴油机...

佛教“前弘期”①的藏族文化概述

第一代藏王聂赤赞普后依次由穆赤赞普、定赤赞普、索亦赞普、梅亦赞普、达赤赞普、赛赤赞普继位,他们就是史书所称的“天赤七王”。关于那个时期的文化尚不见史料记载。此后由智贡赞普继位,他跟一位大臣斗武时佩有胄甲,据说这就是藏族历史上最早使用的胄甲。此后由布德贡嘉继位,由“七良臣”中的第一位,如烈杰大臣佐政这时开始铸造犁铧,引水灌田,农业有所发展,并随着金属资源的开发而发明了冶炼技术;桥梁交通亦有发展。此外还有“本”、“仲”、“德”也可算是这个时期的文化。此后由耶肖雷继位,其大臣拉乌果嘎是“七良臣”中的第二位,此时开始丈量土地,确定牲畜的计算单位、

阿尔泰的滑雪板

拉拖特的《史集》和李文田的《蒙古秘史·注释》,都谈到阿尔泰山区乌良海人、乃曼人,冬天在森林里打猎,由于雪深,就在脚上穿戴滑雪板,手拿木棒以撑地,滑行于雪面上,有如水上行舟。他们这样用滑雪板驰逐于原野上下,追杀野牛,围捕草鹿。滑雪板除用作人们滑行工具外,还可以在其后面拖着他们捕获的野兽,以及运输面粉、日常用品进山,

Prediction of overbreak depth in Ghalaje road tunnel using strength factor

It is well known that the overbreak caused by the blasting damage during tunnel excavation increases costs associated with filling the collapsed area with shotcrete and results in filing of a claim by the contractor. This paper outlines a new approach for prediction the overbreak depth during tunnel construction. Hence, firstly excavation damage zone(EDZ) are determined by average specific charge in each zone. Numerical modelling is used to simulate the EDZ around tunnel boundary and the overbreak depth are calculated by the rock strength factor. The predicted overbreak depth compared with observed field data from a case study. The results show that there exists an approximately up to 40% difference between the prediction and the observed volume of overbreak depth. Therefore, the method can be well used to predict the overbreak depth to estimate more precision of shotcrete and concrete volumes in tunnelling cost during design phase.

Treatment of Protrusion of the Lumbar Intervertebral Disc by TCM Massage

Protrusion of the lumbar intervertebral disc is a common disorder frequently encountered in clinic. With TCM massage and the maneuver of manual reduction, we have treated 82 cases of protrusion of the lumbar intervertebral disc, with satisfactory therapeutic results reported in the following.……

Automatic Guidance of an Agricultural Tractor along with the Side Shift Control of the Attached Row Crop Cultivator

This paper presents the automatic guidance system of an agricultural tractor and the side shift control of the attached row crop cultivator using electro-hydraulic actuators. In order to simulate the dynamic behaviour of the tractor along with the attached cultivator, the modified bicycle model was adopted. Steering angle sensor, fibre optic gyroscope （FOG） and RTK-DGPS technologies are assumed for measurements of the steering angle, yaw rate and the lateral position of the tractor, respectively. The kinematics model was used for the implement. In this study four cascade controllers were designed and simulated for tractor guidance which consists ofPD, PD, P and PID controllers. Other PI and PID controllers also had been designed for implement side shifting purpose. Then, these two systems were combined and the performance of the whole system was evaluated through the simulation results. According to the results tractor reaches the desired path after less than 10 seconds. Simulations showed that the maximum deviation of the tractor from the desired path was about 5 cm within this period. And the cultivator blades would follow the predetermined path with steady state error of about 5 cm too.

Path-tracking Control of a Tractor-aircraft System

An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual prototyping model of the tractor-aircraft system based on Lagrange＇s equation of the first kind with Lagrange mutipliers was established in this paper, According to the towing characteristics, a path-tracking controller using fuzzy logic theory was designed. Direction control herein was carried out through a compensatory tracking approach. Interactive co-simulation was performed to validate the path-tracking behavior in closed-loop, Simulation results indicated that the tractor followed the reference courses precisely on a flat ground.

Endurance Test of Biodiesel Fueled Tractor Engine

A diesel engine for tractor was tested for 250 hours of durability with biodiesel fuel of 100%. An engine test cycle was designed based on the ISO test code of off-road vehicle. Eight test conditions, combination of three engine speeds and eight engine loads, were applied to the engine endurance test, and the engine was operated for eight hours in a day. Power output, fuel consumption rate, exhaust gas quality and particulate matter （PM） were measured and discussed. For the extensive 250 hours of the tractor diesel engine endurance test no significant changes of power output, fuel consumption rate, exhaust gas quality and PM were monitored and authors could not find any difference in the engine patterns of the two fuels of BDF100 and light oil. During all the engine endurance test conditions, no abrupt stopping was encountered but because of temperature down by the cold season the endurance test could not carried out for some periods. PMs were collected and the average F＇M was 0.027 g/kw which was far below than Tier 4 diesel engine PM of 0.3 g/kw h defined by US EPA PM of the diesel engine clas,;. Overall even 100% biodiesel can be an alternative fuel for light oil for diesel engine operation with some considerations for cold sea：son use.

Development of a Data Acquisition System to Optimizing the Agricultural Tractor Performance

A novel data acquisition system was successfully integrated on-board the Massey Ferguson 3,000 series agricultural tractors for measuring tractor-implement performance. A commercial load cell was incorporated into the existing system for the needed tractor-implement performance, measurements. This system is capable of measuring, displaying and recording, in real-time, the tractor＇s theoretical travel speed, the actual travel speed, the engine speed, the fuel consumption rate, and the drawbar pull. Static calibration tests on various associated sensors for the required measurements show excellent linearity with correlation coefficients that are close to 1. The developed system was extensively and successfully field demonstrated for tractor-implement performance with offset disc harrows on dry, undisturbed loamy soils. Under these conditions, a ratio of tractor power to implement width is suggested. The data also show the existence of a linear relationship between fuel consumption per hectare and specific draught, for the 4 to 9 kN m^-1 range, which suggests the possibility of extending the American Society of Agricultural and Biological Engineers model of draught prediction to forecast fuel consumption. The configuration of the tractor-harrow combination, based on the measurement of the draught required under operational conditions, provides the manufacturers with a reliable indication of the recommended power required for each harrow model. With this type of information farmers can make decisions regarding selection of a suitable tractor-implement combination for their farms. As a consequence, there is improved tractor-harrow productivity and field efficiency.

Study on dynamic model of tractor system for automated navigation applications

This research aims at using a dynamic model of tractor system to support navigation system design for an automati- cally guided agricultural tractor. This model, consisting of a bicycle model of the tractor system, has been implemented in the MATLAB environment and was developed based on a John Deere tractor. The simulation results from this MATLAB model was validated through field navigation tests. The accuracy of the trajectory estimation is strongly affected by the determination of the cornering stiffness of the tractor. In this simulation, the tractor cornering stiffness analysis was identified during simulation analysis using the MATLAB model based on the recorded trajectory data. The obtained data was used in simulation analyses for various navigation operations in the field of interest. The analysis on field validation test results indicated that the developed tractor system could accurately estimate wheel trajectories of a tractor system while operating in agricultural fields at various speeds. The results also indicated that the developed system could accurately determine tractor velocity and steering angle while the tractor operates in curved fields.

An Autonomous Electric Powered Tractor--Simulation of All Operations on a Swedish Dairy Farmagricultural m machinery. This s study investig gated the feasib bility of an au utonomous batte ery electric tra actor through simulation. The e

For a conventional agricultural tractor the main environmental effects origina ates from the usage phase, more specifically from the diesel use and exhausts. To decre ease the environ nmental effect, it is vital to find a substitute for fossil diesel as a fuel for agricultural machinery. This s study investig gated the feasib bility of an autonomous battery electric tractor through simulation. The simulated farm is an organic dairy farm of 200 ha with five crops in the crop rotation cycle and a traditional plough among the used implements. Based on the res sult from the simulation cost calculations, sensitivity analysi is and a limited life cycle analysis （LCA） was made. The results show that it is in theory possible to replace a conventional tractor （160 kW） with two autonomous battery powered machines （36 kW engine, 113 kWh battery） with 15% lower costs. Energy consumption would be red duced by 58% a and greenhouse gas emissions by 92% compared to diesel when energy consumption and greenhouse gas emissions from battery manufacturing were included. Today the technology for autonom mous control is under fast development, but there are yet no systems on the market that can handle all machinery tasks like assumed in this study. Challenges yet to solve are , among others, legislative, relevant sensors, logistics and fleet management. Further rese earch is needed to verify the results in practical farming.

Calculation of the Losses of Series-Hybrid Powertrains

Regarding mobile machinery, particularly agricultural tractors, there is an ongoing competition for the most suitable technology to achieve optimum functionality with maximum efficiency. In this competition, the efficiency of electric series-hybrid powertrains （ESHPs） is often depicted as worse than the efficiency of mechanical-hydraulic power-split powertrains （MHPSPs）. On closer inspection of these statements, however, systematic errors, such as unequal balance limits, neglected size effects and nonlinearities, non-observance of recent technical developments and standards, or erroneous application of research results regarding MHPSPs on ESHPs are often evident. For verification （and under avoidance of the systematic errors mentioned above）, the losses of an ESHP of 150 kW power are for example calculated and compared with the losses of a typical MHPSP of the same power. The comparison of the losses shows that the ESHP clearly exceeds the efficiency of the comparative MHPSP in the main working range and that there is still potential for improvement.

Comparison of Economic Life of Tractors in Iran Using Condition Monitoring （CM） and Breakdown Maintenance （BM） Methods

Repair and maintenance costs are the most important factors affecting decision making about substituting agricultural machineries. This decision is made based on the economic life （time） of machineries. In this research, condition monitoring of MF285 and MF399 tractors was performed using engine oil analysis to find the optimum life time of tractor substitution in comparison with the breakdown maintenance method in Iran. All recorded information about fixed and variable costs were selected as data base and analyzed. Data were divided （classified） based on period of annual working time. Using power regression analysis led to find mathematical models for the optimum time life definition. Cumulative working time （X） was selected as independent and cumulative costs based on definite percent of initial price （Y） was considered as dependent variable and a power law equation was found to express the costs of both MF399 and MF285 tractors as a function of working time. Results showed that in CM method, average of economic life was 13 and 11 years for MF399 and MF285, respectively. It was also found that in BM method, economic life wasl0 and 8.5 years for MF399 and MF285, respectively.

Performance of Tractor Diesel Engine with Animal-Fats Biodiesel

Animal fats biodiesel were manufactured and tested for its performance in the tractor engine and fuel adoptability in the field works. Four different fuels, three different content of biodiesel （BD20, BD50 and BD100） and light oil, were prepared and tested in the four strokes diesel engine. Power output, fuel consumption rate and exhaust gases of the four fuels in the diesel engine were compared and discussed. Power output of light oil engine was the greatest showing 5.3% difference between light oil and BDI00. But, almost no power difference between light oil engine and BD20 engine, light oil engine produced 0.37% more power than BD20 engine superior to better power than BD20 engine. Less exhaust gases of CO2, CO, NOx and total hydrocarbon （THC） were produced from animal fats biodiesel than light oil, which confirmed that biodiesel is environmental friendly fuel. For fuel adoptability in the tractor, biodiesel engine tractor showed its fuel competitiveness comparing with light oil for tractor works in the paddy field.

Torsional Vibration Analysis of an FR Driveline System

Towing tractor drivelines are lightly damped non-linear systems. Interactions between components can cause dynamic behavors such as gear gap impact in gear transmissions, shuffle and clonk phenomena in driveline. The torsional vibration of driveline has an important effect on grand engineering vehicle vibration and noise. Through analyzing torsional vibration equations of driveline, torsional vibration model of driveline is developed by using Matlab/Simulink software, Shuffle and clonk phenomena are observed in torsional vibration. The modeling method of analysizing driveline torsional vibration can be used to research and improve similar engineering vehicle driveline behavors.

Fifty-six Cases of Protrusion of Lumbar Intervertebral Disc Treated by Penetration and Oral Administration of Chinese Decoction Plus Traction

Fifty-six cases of the protrusion of the lumbar intervertebral disc in the treatment group were treated by drug-penetration and oral administration of traditional Chinese decoction plus traction, and the other 35 cases in the control group by oral administration of Chinese decoction and traction. The results showed that the cure rate in the treatment group was 83.9%, and that in the control group was 57.1%, with a statistically significant difference between the two groups (P<0.01), indicating that the former is a more effective therapy for protrusion of the lumbar intervertebral disc.

The Effect of Pulverization Equipment Types and Tractor Velocities on Some Technical Indicators for Machinery Unit

This experiment was conducted in silty clay loam soil and cultivated with previous season wheat. Tillage for experiment field was applied using moldboard plow with 0.22-0.24 m depth, the rate of tractor velocity was 2.45 km hf^-1, as a tillage velocity. Two rates of tractor velocities （first factor） were applied： 3.24 km hr^-1, for the first velocity, and 4.71 km hr^-1 for the second, Three types of tillers （second factor） were used： disk harrow, rotavator tiller, and spring spike tooth harrow. The first velocity rate was： 2.51 km hr-l（with disk harrow as a machinery unit）, 2.92 km hr^-1 （with rotivator）, and 3.06 km hrl（with spring spike tooth harrow）, while the second velocity rate was： 3.19 km hr-1 （with disk harrow as a machinery unit）, 4.05 km hrl（with rotivator）, and 4.26 km hrl（with spring spike tooth harrow）. Split plot design in RCBD with three replicates was used at the constant of soil moisture 11%-13%. Results were analyzed statistically and means were tested with LSD. The results showed the significant differences between both two experiment factors and their interaction for all study parameters which included： slippage percentage, practical productivity, numbers of masses 〉 5 cm m^-2, and the implement width. At the constant of pulverization equipment types, the higher percentage of slippage was 16.45%, the higher rate of practical productivity was 0.677 h hr1, and the higher rate of implement width was 2.05 m, while the rate of masses 〉 5 cm m-2 decreased to 13.8 mass m2. At the constant of velocity, disk harrow achieved higher slippage percentage 17.69%, spring spike tooth harrow tiller achieved higher practical productivity 0.858 h hr^-1 and higher rate of implement width 2.73 m, and the rotivator achieved the lower rate of masses 〉 5 cm m2 and 4.1 mass m2. The comparison among the three pulverization equipment typess was the purpose of this study to give the best studied indexes under two different velocities.

Evaluation of Therapeutic Effect of Maneuver-Dominated Method in 30 Cases of Cervical Spondylotic Myelopathy

Thirty cases of cervical spondylotic myelopathy (CSM) were treated by a maneuver-dominated non-surgical therapy. Eighteen cases were recovered to grade E according to the criteria set by the American Spinal Injury Association. The effect was definite. Indications and contraindications of the maneuver were proposed on the basis of the pathogenesis of CSM and the principles of this manual method.

Evaluation of Environmental Impacts in the Wood Skidding with Tractors in Greece

The contemporary demands of the forestry exploitation for quantitative and qualitative increase of timber production are directly related with the mechanization of the wood skidding works. In Greece, the suitable machinery for wood skidding are those with low amortization, operation and installation expenses, are flexible, and may also be used for other farming works （since they are not used very often for wood skidding） and cause the smaller damages to the wood, the forest, the soil and the environment in general. In this paper, it studies the environmental impacts in the remaining stand as much as during the pre-skidding as well as during the main wood skidding with tractor in the forest of Arnaia, Prefecture of Halkidiki, in order to draw out useful conclusions for the improvement of the machinery application methods and the protection of the environment.