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1.
The advantages and disadvantages of varying mixture proportion of crimson clover (Trifolium incarnatum L.) and Italian ryegrass (Lolium multiflorum Lam.), used as winter cover crops, and cover crop biomass management before maize sowing (Zea mays L.) were studied in a series of field experiments in Eastern Slovenia. Pure stands and mixtures of cover crops on the main plots were split into different cover crop biomass management subplots: whole cover crop biomass ploughed down before maize sowing, aboveground cover crop biomass removed before ploughing and sowing, or aboveground cover crop biomass removed before sowing directly into chemically killed residues.Cover crop and cover crop biomass management affected the N content of the whole aboveground and of grain maize yields, and the differences between actual and critical N concentrations in the whole aboveground maize yield. The whole aboveground and grain maize dry matter yields, and the apparent remaining N in the soil after maize harvesting, showed significant interaction responses to cover crop × management, indicating positive and negative effects. Crimson clover in pure stand provided high, and pure Italian ryegrass provided low maize dry matter yields and N content in the yields in all the observed methods of biomass management. However, within individual management, mixtures containing high proportions of crimson clover sustained maize yields and N contents similar to those produced by pure crimson clover. Considering the expected ecological advantages of the mixtures, the results thereby support their use.  相似文献   

2.
This article introduces new progress of research on theory and application of superconductivity, especially for year 2001. In reconsidering superconductive microscopic mechanism, the evidence shows to exist for strong electron_phonon coupling in high_temperature superconductors. In exploring new superconductive materials,there mainly are MgB 2, P3HT and C60,etc.superconductive applications outlook both practical and potential seem good, expecially,such as energy resource,electric force,microwave telecommunication,computer,medical cave and various dectors,etc.  相似文献   

3.
Based on structure analysis software ANSYS, a non-linear complete-process analysis of stability behavior of single-layer latticed domes with different span and different rise-span ratio and different section is carried out. The effect of unsymmetrical loading distribution to the stability behavior of single layer latticed domes with various parameters is also analyzed. Some important conclusions are acquired and can be used as guidance to engineering design.  相似文献   

4.
The 'Design and Build' contract mode is a new contract and managerial approach, to which more and more attention has been paid. Now it becomes the contracting tendency in the international construction market. In this paper, the basic theories and method of the 'Design and Build' mode are widely and systematically studied. It specifies the intention of the 'Design and Build'contract mode, existing problems and corresponding countermeasures as well as its developing direction.  相似文献   

5.
Winter wheat production in northern China severely suffered from high temperatures and low relative humidity. However, the spatio-temporal pattern of heat stress and dry stress and the impacts of these multi-hazards on winter wheat yield have rarely been investigated. Using historical climate data, phenology data and yield records from 1980 to 2008, an analysis was performed to characterize the spatio-temporal variability of heat stress and dry stress in the post-heading stages of wheat growth in northern China. Additionally, these stresses’ impacts on winter wheat yield fluctuations were evaluated. Spatially, the central and northern parts of northern China have seen more serious heat stress, while greater dry stress has been observed in the northwest and north of the research area. Temporally, the heat stress has increased in the western part but decreased in the central and eastern parts of research area. Dry stress has aggravated in the entire northern China during the past decades, indicating the complexity of the exposure to adverse climate conditions. These two hazards (heat stress and dry stress) have contributed significant yield loss (up to 1.28% yield yr−1) in most parts of the research region. The yield in the west was more sensitive to heat stress, and dry stress was the main hazard in the south. Additionally, the opposite spatial pattern between the sensitivity and exposure revealed that the climate is not the only factor controlling the yield fluctuation, the local adaptation measures used to mitigate negative influences of extreme events should not be ignored. In general, this study highlighted a focus on the impacts of multi-hazards on agricultural production, and an equal importance of considering local adaptation ability during the evaluation of agricultural risk in the future. Additionally, paying more attention to higher sensitive areas and to more reasonable and practical adaptive strategies is critical and significant for food supply security.  相似文献   

6.
The inelastic dynamic response analysis program for frame-shear wall structures developed by the authors is introduced firstly, in which the multi-vertical-line-element model was adopted for shear walls and the refined single-component model was used for beams and columns in frame.By analyzing three-story structural models tested in shaking-table in a famous foreign research institute, the validity of the modeling of shear wall in the program was verified. The analytical results indicate that the inelastic dynamic responseof shear walls under random ground motion input can be predicted effectively withthe program. Finally, with the preliminary discussion of some key points in modeling of shear wall, some suggestions areput forward for further improving and refining the multi-vertical-line-element model.  相似文献   

7.
Aiming at insufficiency exists in the process of machinery fault diagnosis at present, the paper takes consider of the application of information fusion technology in fault diagnosis to make fault diagnosis effectively. The applications of information fusion methods based on neural network, the Bayesian theory and the D-S theory are discussed in detail. Example is also given to explain the validity of information fusion technology in diagnosis analysis.  相似文献   

8.
The study on automatic balance of the rotor was made both from theory and ap-plication.In the light of the feature of automatic balancing,new analysis about the mechanical modelof vibratory system was done,and the result is that the accurate model of system can be gained bycompensation method and the traditional principle errors of balance machine both for soft and hardbearing can be overcome.The autornatic balance testing theory was proposed.The automatic balancesystem has been developed a nd the fu n ction a nd techn ical key are also discussed in detail.  相似文献   

9.
The sustainability assessment of construction project will play an important role in promoting the implementation of sustainable development strategy. The indicator system and standards for sustainability assessment of construction project are discussed in this paper, and then the application mode of sustainability assessment in China is analyzed. A proposal is also put forward in this paper that the sustainability assessment of construction project should be implemented in stages and combined with the feasibility study and environmental impact assessment system.  相似文献   

10.
Intelligent buildings are more convenient and comfortable, however, their energy consumption during the operation arouses a big concern in society. In this article air - conditioning system operation control is studied mainly, meanwhile, to develop a kind of energy - saving air - conditioning system and put forward a strategy of energy conservation in air - conditioning, based on the calculation of the target on - line optimized function.  相似文献   

11.
CAE system of networked collaborative is communication of the related information in the period of CAE analysis and developed design.The research of automotive engine CAE system is introduced.The results of(developed) design,FEA(Finite Element Analysis),static/dynamical and distortion analysis,and calculation of radiant noise for the engine cylinder is showed the importance to the developed design of engine.The analyses and design of the product is developed for the development and application of CAE system,and the analysis ability of engineer is improved.  相似文献   

12.
A method of constructing GPS-based positioning services system by means of JAVA technology is introduced in this paper. The position data, which are sent from GPS satellites, are received by GPS receiving terminal and are analyzed by mobile computing client developed on J2ME in accordance with the differential GPS algorithm. The client submits special position querying information to position server in way of wireless GPRS network. After computing and data querying, the server developed by J2EE returns results to the mobile device. Then, the mobile computing client displays the position map or carries out further processing. All of these form a highly precise location-based services system.  相似文献   

13.
The fundamental principle and mechanical behavior of several intelligent material systems, such as shape memory alloy, piezoelectricity and fiber optic sensor etc. are discussed in this paper. Some application to civil engineering structures and related research are introduced briefly. The existing problems in the application and research are also presented at the same time. The future development of the intelligent material systems and structures are prospected and some proposals are put forward.  相似文献   

14.
The modal parameters are the key indexes for the damnification diagnosis and state evaluation. But for the complexities of the structure and soil interaction effect mechanism of cantilever retaining wall system, there is still no appropriate ways to simulate the modal parameters effectively at the moment. To solve the existing problem, practical modal parameters of structure system were obtained by field impulse hammering modal test. Compared them with the modal parameters of structure system ignoring the soil influence, it was concluded that the soil influence can not be ignored. And with the consideration of soil influence, calculation methods of additional stiffness and mass were analysed and modal analysis with the finite element method was undertaken for the retaining wall as well. It was approved that the calculating method for soil influence and impulse hammering modal test is feasible with good agreement with data from field test. Finally, the main disabled modes of the retaining wall, the modal parameters characteristics under damage state and health diagnosis methods were studies and a fast, simple, lossless and effective modal analysis evaluation method was proposed for the health diagnosis of cantilever retaining wall.  相似文献   

15.
The characteristics of work piece's surface under precision abrasive belt grinding are analyzed.A comprehensive understanding of the reason of low roughness value's surface is found out,which the edge of grain formed compact and crossed micro grinding marks that can compensate for the inconsistence of grinding mark's height in single grinding direction.The grinding test of gear shaft is done for the sake of doing research on the main factors of surface roughness in grinding quenching stainless steel.The results indicate that decreasing the vertical pressure is beneficial to(reduce) surface roughness of work piece,and the surface roughness also can reach the requirement of precision processing when steadily grinding.  相似文献   

16.
Summary Sensitivity to GA in non-Gai genome winter wheat (Triticum aestivum L.) cultivars was investigated to determine magnitude of variation of the trait, its association with other traits, and effects of geographical location of production. -Amylase enzyme activity was measured before and after treatment with gibberellic acid in 18 cultivars grown at one location and in five cultivars grown at six locations. Dye-labeled starch and agar-starch media procedures were used for the first and second experiments, respectively. -Amylase activity differed significantly among the 18 cultivars after germination in water, germination in GA, and in absolute and relative sensitivity to GA. Cultivars that reacted similarly to GA had some common ancestors in their pedigrees, and -amylase activity and sensitivity to GA were significantly negatively associated with seed weight. -Amylase activity differed between tall and semi-dwarf cultivars in the second experiment, but not in the first experiment. The magnitude of variation in -amylase activity and its relationship to preharvest sprouting susceptibility of the cultivars suggested that the trait can be modified to improve seed dormancy. Significant interactions between cultivar responses to GA and geographical location of grain production suggested that selection should be carried out in several environments.Contribution no. 81-162-j, Department of Agronomy, Kansas State University, Manhattan KS 66506, USA.  相似文献   

17.
According to the instant demand coming from the collaborative product development of small and medium manufacturing enterprises, this paper brings out a kind of a collaborative product development service-on-demand mode based on web-service, and a framework for this service-on-demand mode are also given. According to these, this research sets up a web based collaborative product development service platform, analyzes the function structure, service flow and the main implement techniques. The service pattern and the platform have already applied to collaborative product development in small and medium manufacturing enterprises and have helped to increase technique innovation, reduce the total time and cost in development process.  相似文献   

18.
19.
采用5因素5水平正交施转回归设计,对陕西水地棉花高产栽培技术中的密度、肥料、缩节胺等5项主要农艺措施进行了深入研究。结果表明:各因素作用大小依次为密度>缩节胺>尿素>硫酸钾>二铵。研究了各项农艺措施间的交互作用对产量的效应,获得了≥1875kg/hm2最佳农艺措施组合方案,通过反馈示范,提高了棉花产量。  相似文献   

20.
Effects of N, P and K Fertilizers on the Yield of Cauliflower   总被引:3,自引:0,他引:3  
以花椰菜“厦雪100天”品种为试材,采用通用旋转组合设计,通过田间试验,对氮、磷、钾肥用量与花椰菜产量间的关系进行研究,建立了花椰菜产量函数模型;结果表明:氮、磷、钾肥均能显著地影响花椰菜产量,其作用大小依次为氮肥>钾肥>磷肥;在此项试验条件下,施肥量为N:319.58~371.48kg/hm2,P2O5:202.20~261.45kg/hm2,K2O:288.15~339.15kg/hm2时,花椰菜产量可达57000kg/hm2以上。  相似文献   

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