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Cultivated land is the foundation of human existence and development. Eco-efficiency of Cultivated Land Use (ECLU) is a comprehensive index to measure the economic, social, and ecological output of cultivated land. Therefore, it is of great theoretical and practical significance to describe the evolution characteristics of ECLU, and to explore the improvement path of ECLU for realizing the sustainable utilization of cultivated land resources, coping with the food crisis, and alleviating global warming. Hubei Province, as a traditional major province of grain production in China, can provide a reference for other developing countries in the world in terms of its management experience and technology in the production and utilization of cultivated land. In this study, the carbon emissions and pollution emissions of cultivated land use were incorporated into the calculation system of ECLU. Firstly, the undesired super-efficiency Slack-Based Measure (SBM) model was used to calculate ECLU in Hubei Province from 2008 to 2020. Secondly, the Exploring Space Date Analysis (ESDA) method was used to characterize its temporal and spatial evolution characteristics. Finally, the improvement direction of ECLU in the future was proposed from the perspective of cultivated land input factors. The research shows that, first of all, from 2008 to 2020, ECLU in Hubei Province showed a fluctuating growth trend, rising from 0.457 to 0.521, during which, it experienced two “U”-shaped changes, in 2011 and 2016. Secondly, the spatial agglomeration effect of ECLU in Hubei Province continued to increase, mainly showing two agglomeration patterns of high–high and low–low. Finally, ECLU in the study area was significantly negatively correlated with the redundancy rate of input factors. There was a redundancy in the input factors of cultivated land production, among which, the redundancy degree of agricultural employees (AM), chemical fertilizer usage (CFU), and total power of agricultural machinery (AMP) were more serious. Based on this, this paper proposes to adhere to the principle of adapting measures to local conditions and progress in an orderly manner, and to formulate differentiated and phased policies for improving ECLU according to natural resource endowments, and social and economic development conditions in different regions, in order to achieve the coordinated and sustainable development of people and cultivated land.

We introduce a new measure to assess the valuation skills of investment-grade corporate bond funds. Our measure recognizes funds that ex-ante hold a higher fraction of undervalued bonds as having better valuation skills. The measure predicts future fund performance, is stable over time, and is unrelated to other sources of skill. Fund investors recognize such skill by responding more to the past performance of funds with better valuation skills. Consistent with the equilibrium model of Gârleanu and Pedersen (2018), our evidence suggests that as growing capital gets allocated to skilled bond funds, the corporate bond market is becoming more efficient.

The essence of parameter estimation for fractional-order chaotic systems is a multi-dimensional parameter optimization problem, which is of great significance for implementing fractional-order chaos control and synchronization. Aiming at the parameter estimation problem of fractional-order chaotic systems, an improved algorithm based on bird swarm algorithm is proposed. The proposed algorithm further studies the social behavior of the original bird swarm algorithm and optimizes the foraging behavior in the original bird swarm algorithm. This method is applied to parameter estimation of fractional-order chaotic systems. Fractional-order unified chaotic system and fractional-order Lorenz system are selected as two examples for parameter estimation systems. Numerical simulation shows that the algorithm has better convergence accuracy, convergence speed and universality than bird swarm algorithm, artificial bee colony algorithm, particle swarm optimization and genetic algorithm.

Abstract. This article chose 19 state-owned enterprises which were listed as a whole during 2004-2013, using factor analysis to compare financial performance of them among the year before holistic listing, the year of holistic listing and the year after holistic listing. The result revealed that holistic listing is not panacea for state-owned enterprises to improve their financial performance. Besides holistic listing, the enterprises should improve their corporate governance and management efficiency as well.