OPTIMAL INVESTMENT IN THE PROTECTION OF A VULNERABLE BIOLOGICAL RESOURCE

It is assumed that the probability of destruction of a biological asset by natural hazards can be reduced through investment in protection. Specifically a model, in which the hazard rate depends on both the age of the asset and the accumulated invested protection capital, is assumed. The protection capital depreciates through time and its effectiveness in reducing the hazard rate is subject to diminishing returns. It is shown how the investment schedule to maximize the expected net present value of the asset can be determined using the methods of deterministic optimal control, with the survival probability regarded as a state variable. The optimal investment pattern involves “bang-bang-singular” control. A numerical scheme for determining jointly the optimal investment policy and the optimal harvest (or replacement) age is outlined and a numerical example involving forest fire protection is given.     

Robust Speed Control of a Low Damped Electromechanical System Based on CRONE Control: Application to a Four Mass Experimental Test Bench

Robust speed control of a low damped electromechanical system with backlash is studied, controlled load angular speed being not measured. The proposed control strategy combines a Luenberger observer (load angular speed and load torque disturbance estimations) and a robust CRONE controller. The observer provides estimation of the load angular speed and of the disturbance torque applied on the load. Through the computation of only three independent parameters (as many as a PID controller), the CRONE controller permits to ensure the robust speed control of the load in spite of plant parametric variations and speed observation errors. The proposed control strategy is applied to a four mass experimental test bench.     

On weak spreadability of distributed-parameter systems and its achievement via linear--quadratic control techniques

In this paper, the concept of weak spreadability is introduced.It constitutes an extension of the idea developed by El Jai& Kassara. In the case of linear distributed systems weconsider quadratic control techniques with a conveniently penalizedcriterion which makes the system weakly spreadable. The approachis outlined for a convection—diffusion system, and theresults of a numerical study are also included to illustratethe main features of the considered problem.     

OPTIMAL INSTAR PARASITIZATION IN A STAGE STRUCTURED HOST-PARASITOID MODEL

A stage structured host-parasitoid model is derived and the equilibria studied. It is shown under what conditions the parasitoid controls an exponentially growing host in the sense that a coexistence equilibrium exists. Furthermore, for host populations whose inherent growth rate is not too large it is proved that in order to minimize the adult host equilibrium level it is necessary that the parasitoids attack only one of the larval stages. It is also proved in this case that the minimum adult host equilibrium level is attained when the parasitoids attack that larval stage which also maximizes the expected number of emerging adult parasitoid per larva at equilibrium. Numerical simulations tentatively indicate that the first conclusion remains in general valid for the model. However, numerical studies also show that it is not true in general that the optimal strategy will maximize the number of emerging adult parasitoid per larva at equilibrium.     

Motion Control by ZV Shaper Synthesis Extended for Fractional Systems and Its Application to CRONE Control

Shaping command input or preshaping is used for reducing system oscillation in motion control. Desired systems inputs are altered so that the system finishes the requested move without residual oscillation. This technique, developed by N.C. Singer and W.P. Seering, is used for example in the aerospace field, in particular in flexible structure control. This paper presents the study of ZV shaper for explicit fractional derivative systems (generalized derivative systems). A robustness study of ZV shaper is then presented and applied to improve second generation CRONE control response time. Results from simulation and from a DC motor bench are also given.     

Boundary control of a hyperbolic system with time lags

This paper considers an optimal boundary control problem fora hyperbolic system in which constant time lags appear in thestate equation and in the boundary condition simultaneously.Making use of Lion's scheme, necessary and sufficient conditionsof optimality for the Neumann problem are derived.     

Necessary and sufficient conditions for the existence of positive solutions to algebraic Riccati equations with indefinite quadratic term

Necessary and sufficient conditions are established in this paper for the existence of positive- and/or negative-definite solutions to the algebraic Riccati equation with indefinite coefficient. An iterative procedure is also given for computing such a solution.Project supported by the National Science Foundation of China and by the special program of the State Education Commission of China under grant 9033507.     

UPLC-MS-Based Metabolomic Study of Streptomyces Strain HCCB10043 Under Different pH Conditions Reveals Important Pathways Affecting the Biosynthesis of A21978C Compounds

The A21978C family of compounds includes precursors of daptomycin, an important antibiotic for the treatment of diseases infected by Gram-positive resistant bacteria. Focusing on these valuable compounds, the differences in metabolites obtained with or without pH control in their producing strain Streptomyces parvus HCCB10043 were investigated by comparative metabolomics analysis based on UPLC-TOF-MS technology. According to principal component analysis, there were fourteen biomarker compounds selected under the two pH culture conditions. The ten known compounds were divided into two types: a glycoside family participating in the primary metabolism (daidzein, glycitein, genistein, and soyasaponin Bb) and a peptide family of secondary metabolites (valistatin, bestatin, 3-amino-2-hydroxy-4-phenylbutanoylvalylisoleucine, and arylomycins A2, A4, and A5). Through orthogonal partial least squares-discriminant analysis, three compounds, soyasaponin Bb and arylomycins A2 and A4 were identified as the most relevant compounds to A21978C1-3 production, the glycolytic pathway, and the NRPS synthesis pathway. The competitive relationship between arylomycin and A21978C was verified. These results have demonstrated the usefulness of the metabolomic strategy based on UPLC-MS in studying significant metabolic changes in actinomycetes. Moreover, this metabolomic strategy can provide new ideas and guidance for the regulation and improvement of secondary metabolites production.     

稀土对小麦（Triticum aestivum）体内光合和呼吸速率及磷酸化功能的影响

以适当浓度稀土溶液处理小麦后，其光合和氧化磷酸化的磷氧比（Ｐ／Ｏ）、光合控制（Ｐｃ）、呼吸控制（ＲＣ）、状态３．４光合和呼吸速率（Ｓ３．Ｓ４）与对照样比均无显著性差异。状态２（Ｓ２）光合和呼吸速率提高，差异极显著。说明小麦用最适浓度稀土处理后，对其光合和呼吸的磷酸化机构和功能膜影响不大，但显著促进了光合和呼吸速率（Ｓ２），从而促进了电子传递链的活性，使ＡＴＰ形成量增加。     

多层绝热材料规模化干燥处理时温度场的测试与分析

对大批量处理多层绝热材料的大型专用干燥箱满负荷运行时工作区域的温度场进行测试,通过温度分布和温度场均匀性的分析,得出了最高温度发生点的位置与成因以及影响温度场均匀性的主要因素,并对温度的控制方法、多层材料的布置方案和干燥设备的改进提出了建议。