Security of cultivated land resources is the basis for cultivated land protection and national food security.Bayan County as an important base for marketable grain production in the black soil zone of Songnen High Plains was selected as research region.Natural,economic,social and ecological indices were incorporated to establish an evaluation index system in this study.The method of optimal combination was applied to establish index weights,and the method of synthetic index was used to quantitatively evaluate the operation status of the security of cultivated land resources in Bayan County from 2000to 2009.In addition,principal component analysis was conducted to analyze the driving forces.Introducing Cubic curve,the model of security changes of cultivated land resources was established with nonlinear regression analysis to validate the secure values of cultivated land resources and the contribution of driving forces.The results show that the cultivated land security status of the study area differed over time;it is less secure in 2000,extremely unsecure from 2001to 2003,less secure from 2004to 2005,intermediately secure in 2006,and relatively secure from 2007to 2009.According to the analysis,the development of technology,economy,and society,the natural disturbance forces,and the ecological influence were the main driving forces for the security changes.A significant cubic curve relationship was found between the cultivated land resource security and these three kinds of driving forces,reflecting high reasonability and applicability of the model established in this study.
This paper investigates continuous anti-saturation three-dimensional guidance law against maneuvering target at the desired line-of-sight (LOS) angles. Firstly, in the light of fixed-time stability, fast nonsingular terminal sliding mode is designed without the limitation of odd-ratio fractional order. Then, with the limits of lateral acceleration saturation, continuous guidance law is proposed to guarantee that desired LOS angles are reached and maintained after the specified time, while adaptive law is implemented to estimate the information on maneuver accelerations of the attacking missile. Finally, numerical simulations are presented to validate the effectiveness and rationality of the designed scheme.
The problem of cooperative interception of the manoeuvring target is investigated in this paper. Firstly, in light of fast fixed-time consensus theory, time-to-go, and undirected topologies, adaptive cooperative guidance along the line-of-sight (LOS) direction is proposed to guarantee impact time synchronization. Next, novel nonsingular terminal sliding mode (NTSM) is designed to establish adaptive fixed-time guidance law for steering LOS angular rates to the origin or its small neighbourhood. Without the knowledge of target manoeuvre, the proposed cooperative guidance law can be provided by lateral and longitudinal accelerations of each missile, while more reasonable and rigorous analysis of fixed-time stability is carried out through the Lyapunov theory. Within the specified time, both control tasks of simultaneous attack and the desired impact angles can be completed before the final time of the guidance process. Finally, numerical simulations demonstrate the feasibility and effectiveness of the proposed scheme.
The value of woody vegetables was analyzed in detail from aspects of the nutritional value,medicinal health value,economic value and eco-tourism value.A total of 41 species of common woody vegetables were investigated in Tianjin,which belong to 23 families and 35 genera,according to field investigation,oral probe from native,market research as well as reviewing widely literature.The development prospect of woody vegetables was also discussed.
The planning of Dingzi Bay will impact its hydrodynamic and tidal water capacity,thus affecting the water exchange as well as the water quality and ecological environment in Dingzi Bay.In this paper,the tidal current numerical model is developed by two-dimensional tidal motion equation in the west area of Laoshantou to Gulongzui.And the hydrodynamic and tidal water capacity changes are simulated before and after the planning implementation. The simulation results show that the current velocity in most planning regions will increase after the planning implementation,especially in the middle waterway of Dingzi Bay.During flood tide period,the increment of current velocity near the mouth of waterways is the most with more than 0.48m/s,while the maximum increment of ebb tide occurs near Mahe Port Bridge in 0.54m/s or more.However,the velocity changes little in the area outside the Bay. With respect to tidal prism,it will increase by 42% in the connection line of the Hai-Ji sea-crossing bridge and by 33% in the line connecting the Dingzizui and Kaolao island. All the analysis shows that the planning of Dingzi Bay will greatly improve its water dynamic,and increase its tidal water capacity.Therefore the planning is in favor of water exchange of Dingzi Bay and the open sea.the water quality ecological environment in Dingzi Bay will also be improved as well.
Developing specialties in orchard fruits productions with ecological and economic benefits is a practical and effective way to guarantee eco-friendliness and increase farmers’ income in the Loess Plateau area. Therefore, to understand these factors, the study constructs an agriculture ecological cognition index from three dimensions of eco-agriculture cognitions (increase income cognition, water conservation cognition and eco-product price cognition). Our analysis was based on micro survey data from 416 farmers in Shaanxi and Ningxia, China. The study used two main econometric models, double-hurdle and Interpretative Structural Modeling (ISM), to examine the relationship and influence pathways between cognition of ecological agriculture and farmers’ specialty orchard fruit planting behavior. The results show that: (i) the cognition of eco-agriculture affects whether farmers plant specialty fruits (participation decision). The cognition of eco-agriculture increases income and the cognition of eco-product price significantly affect the scale of specialty orchard fruits planting (quantity decision). (ii) Household resource endowments influence specialty orchard fruit planting responses through ecological farming cognitions. (iii) The factors influencing the participation and quantity decisions of orchard fruit planting are significantly different. Therefore, when the government actively encourages farmers to participate in specialty orchard planting, it should fully consider the cognitive factors of ecological agriculture of the growers and develop targeted training strategies.
At present, translation studies, as an interdisciplinary subject, draws on the findings and theories of linguistics, pragmatics, cultural studies, and other domains to develop and formalize its own methods. The growing importance of translation in our age of economical globalization calls for a switch to the economic orientation. Anthony Pym incooperates economics into translation studies, and puts forward the translation as a transaction cost model. The author of this article develops the model into criteria for translation evaluation, i.e. the economical principle and the ethical principle, which provide a new perspective on studying translation.
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