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961.
With the progress of science and technology, the astronautics has obtained great development and researched in many countries, the problem on rocket safety control is important during the rocket launching proceeding, and is also the focus of every space country. At first, the importance of rocket safety control is introduced and the characteristics of the existing system for the safety of rockets are analyzed. After indicating its disadvantages, the design idea, system framework and method for realization of the knowledge-based intelligent decision-making system are proposed to improve certainty and authenticity of safety decision, containing correspond knowledge and adopting the technology of intelligent decision and reasoning on AI. 相似文献
962.
In order to realize elastic-plastic analysis in geotechnical FEA, in this paper, firstly, the method how to realize elastic-plastic analysis in Super-Sap is discussed. Then, this paper stresses to introduce the principle and the steps used to achieve the accomplishment of elastic-plastic analysis in Super-Sap. Finally, an engineering practice is given to prove that the geotechnical FEA elastic-plastic analysis and visualized post-processing can come true by it rapidly. 相似文献
963.
Chen Qigao Feng Ya 《保鲜与加工》1993,(1)
This paper analyses the thermal moist characteristics of the hull layer beside an air layer at lower temperature in an envelope for a cold storage and presents a new method of waterproof by air layer. With test data from engineering practice, the theory on the barrier of self moisture proof at the surface sublayer of the hull layer in an attic on a cold storage is proven. The dried zone about three phase point is confirmed. It is a new knowledge for thermophysics on thermal design of a cold storage with an optimum thermal performance. 相似文献
964.
Ryan B. Mounce Susan A. O’Shaughnessy Brock C. Blaser Paul D. Colaizzi Steven R. Evett 《Irrigation Science》2016,34(3):231-244
In the High Plains, corn (Zea mays L.) is an important commodity for livestock feed. However, limited water resources and drought conditions continue to hinder corn production. Drought-tolerant (DT) corn hybrids could help maintain high yields under water-limited conditions, though consistent response of such hybrids is unverified. In this two-year study, the effects of three irrigation treatments were investigated for a DT and conventional maize hybrid, Pioneer AQUAMax P0876HR and Pioneer 33Y75, respectively. In 2013, the drier of the 2 years, irrigation amounts and crop water use (ETc) were greater for the conventional hybrid, but grain water use efficiency (WUE) and harvest index were significantly greater for the DT hybrid. In 2014, grain yields and WUE were not significantly different between hybrids. However, irrigation amounts, ETc and biomass yields were greater for the conventional hybrid. Results from both years indicate that the DT hybrid required less water to maximize grain yield as compared to the conventional hybrid. Producing relatively high yields with reduced amounts of water may provide a means for producers to continue corn production in a semiarid environment with declining water supplies. 相似文献
965.
Summary Traffic during alfalfa harvest operations can cause soil compaction and damage to newly growing stems. Root exploration for soil water and nutrients, forage growth dynamics, and final yield can all be affected. The objectives of this study were to determine the long-term effects of harvest traffic and soil compaction on water-use efficiency (WUE) of alfalfa grown in a Wasco sandy loam (coarse-loamy, mixed, nonacid, thermic Typic Torriorthents). Alfalfa was planted into tilled soil and managed with or without harvest traffic. Plants subjected to traffic during harvest had a significantly lower WUE two out of the three years studied compared to plants that were never subject to traffic. The second experiment examined whether planting alfalfa into compacted soil and managed with or without harvest traffic altered WUE. Soil compaction had no affect on alfalfa WUE. It was significantly lower when grown in compacted soil and subjected to harvest traffic. It is suggested that the decrease in WUE caused by harvest traffic may be explained by plants allocating carbohydrates to damaged shoots and crowns instead of to above ground forage production. The area of the field affected by harvest traffic, which damages newly growing stems, should be minimized to increase crop water use efficiency. 相似文献
966.
R. L. McCown B. H. Wall P. S. Carberry J. N. G. Hargreaves K. L. Green P. L. Poulton 《Irrigation Science》1990,11(3):189-195
Summary This paper reports on the design and performance of an irrigation system associated with a rain shelter. The shelter is used in the closed position as a platform for multiple spray lines. This system automatically supplies, at a specified time, water of specified depth and delivery rate, either uniformly or on a specified gradient across the sheltered area. Variations in crop water deficits and yields have conformed closely to imposed water gradients. 相似文献
967.
The development of management control techniques for the dairy derd is discussed in this paper in relation to the rationale behind the construction of a detailed model of milk production in the individual cow. The movement towards a more flexible and individualised basis for predicting yield, which does not depend on historical records or standard energy systems, is highlighted.The overall concept and approach of the model are set out and the control aspects and structural framework of the program explained. Subsequent papers in the series will deal in more detail with the major sections of the program in order to illustrate how the mechanisms of the model actually operate and to provide results and an account of the validation procedure. 相似文献
968.
Measuring yield-reducing plant water potential depressions in wheat by infrared thermometry 总被引:1,自引:0,他引:1
Summary Measurements of foliage and air wet- and dry-bulb temperatures were made over six differentially irrigated plots of Produra wheat grown at Phoenix, Arizona, in the spring of 1976. These data were used to evaluate a newly developed plant water stress index each day from the initiation of heading to the commencement of senescence. Daily measurements on total plant water potential were also obtained over this period; and after demonstrating how the atmospheric-induced component can be removed from these data, the resultant soil-induced component was plotted as a function of the new water stress index. The result was a simple linear relationship, which was found to be identical to one previously derived for alfalfa. Finally, it was shown that grain yield was directly related to the mean plant water stress index over the reproductive growth period from heading to senescence.Contribution from Agricultural Research, Science and Education Administration, US Department of AgricultureResearch physicist, soil scientist, research physicist, and research entomologist, respectively 相似文献
969.
A new approach for the estimation and control of the quantity of water applied in an irrigation is presented in which irrigation is stopped when the wetting front reaches a critical depth, Z
L. An expression for calculating the critical depth Z
L was developed. A major parameter in this expression is the velocity of advance of the wetting front, V, which was shown to be directly related to the application rate, IR, and inversely related to the initial soil water content,
i. A depth probe (patent pending) was designed, constructed and tested for the purpose of monitoring the position of the wetting front during infiltration and redistribution and for computing the value of V. Equations developed for relating the velocity of advance of the wetting front to
i as well as for estimating the value of the critical depth Z
L were successfully tested under conditions of uniform distribution of the initial soil water content. An iterative learning process which utilizes the real time output from the depth probe during each irrigation and is therefore capable of handling realistic field conditions where nonuniformity is the rule is presented. The acquired information is used to estimate a critical depth of the wetting front, Z
L, for a planned final wetted depth, Z
F, during each irrigation. This process is incorporated in the depth probe and is used to stop irrigation and thus control the quantity of water applied. 相似文献
970.
The problem of real-time irrigation scheduling under limited water supply is considered. The goal is to develop an irrigation operation policy which maximizes crop yields and is responsive to current season changes in weather and other variables. Because irrigation decisions are sequential and dependent on crop and soil water status, and also because crop yields can only be known at the end of the season, the decisions are arrived at by a two-stage process. In the first or the design stage, irrigations are planned for the entire season at weekly intervals using historical data and an optimal irrigation scheduling model. In the second stage, the decisions for the subsequent weeks are revised each week after updating the status of the system with real time data up to that week and solving the irrigation optimization model once again for the new conditions. Thus, each week an irrigation decision is made, the entire planning horizon is kept in view. The procedure is illustrated by application to a case study. 相似文献