Risk Management Strategy for Agricultural Operation Subjects in Simple Scale Expansion Mode

Agricultural operation subject is a main body of the market economy. At present,the simple scale expansion mode is a major mode of agricultural operation in China. According to some hypothesis,scale expansion will inevitably bring high income,but such hypothesis has serious defects. The operation mechanism of the simple scale expansion mode includes farmer operation mechanism,professional farmer operation mechanism,and " company + farmers" operation mechanism. In the production and operation,they will be faced with different natural risks,technical risks,market risks and policy risks. Besides,their risk control ability is also varied. Therefore,it is required to take different agricultural risk management strategies. The " company + farmers" production and operation subjects have the highest ability of risk management. Other subjects should learn their experience.

A Probe into Economic Regionalization Theory Analysis Framework of Conflicts Between Scale Expansion and Transaction costs

The economic regionalization practice led by China local governments has gradually evolved into chaos. Local governments compete to declare for higher-leveled and large-scaled economic regions to obtain more economic resources and policy support in the way of policy game. The author argues that the regionalization chaos is attributed to the reason that the present theoretical support for economic regionalization overemphasizes the economic growth brought about by the economic regionalization but ignores the effect of transaction cost, which leads to constraint loss on the economic regionalization theory analysis framework. Then, the introduction of economic regionalization analysis framework based on the conflicts between scale expansion and transaction costs would establish equilibrium conditions to set up a moderate scale development for economic regions. The author hopes that the acceptance of this framework into the economic regionalization decision-making system would give guidance for making more appropriate regionalization decisions.

QUASI-NEUTRAL LIMIT AND THE INITIAL LAYER PROBLEM OF THE DRIFT-DIFFUSION MODEL

In this article we study quasi-neutral limit and the initial layer problem of the drift-diffusion model.Different from others studies,we consider the physical case that the mobilities of the charges are different..The quasi-neutral limit with an initial layer structure is rigorously proved by using the weighted energy method coupled with multi-scaling asymptotic expansions.

Baosteel's development of cold strip technology

Throughout 30 years of importation, adoption and innovation, the Cold Rolling Plant of Baosteel has adhered to a market-oriented strategy, and gradually expanded its output and raised its technical level through the expansion of production scale ,the optimization of production lines, the development of high added value products, the improvement of product quality, environmentally friendly manufacturing and technological innovation. In this way, the plant has developed into a world class cold rolling plant that produces cutting-edge economic and technical indices.

Fourier-Mellin expansion coefficients of scaled pupils

Orthogonal polynomials over the interior of a unit circle are widely used in aberration theory and in describing ocular wavefront in ophthalmic applications. In optics, Zernike polynomials （ZPs） are commonly applied for the same purpose, and scaling their expansion coefficients to arbitrary aperture sizes is a useful technique to analyze systems with different pupil sizes. By employing the orthogonal Fourier-Mellin polynomials and their properties, a new formula is established based on the same techniques used to develop the scaled pupil sizes. The description by the orthogonal Fourier-Mellin polynomials for the aberration functions is better than that by the ZPs in terms of the wavefront reconstruction errors.

Quasi-neutral limit of the drift-diffusion model for semiconductors with general sign-changing doping profile

The quasi-neutral limit of time-dependent drift diffusion model with general sign-changing doping profile is justified rigorously in super-norm (i.e., uniformly in space). This improves the spatial square norm limit by Wang, Xin and Markowich.