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RISS 인기검색어
- 검색키워드
- 저자 : Bottrell (검색결과 4 건)
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Potential Strategies for Prolonging the Usefulness of Bacillus thuringiensis in Engineered Rice
Bottrell, D.G.,Aguda, R.M.,Gould, F.L.,Theunis, W.,Demayo, C.G.,Magalit, V.F. Korean Society of Applied Entomology 1992 한국응용곤충학회지 Vol.31 No.3
A laboratory bioassay that incorporates Bacillus thuringiensis (Bt) purified crystal protein toxins into an artificial diet has identified three toxins, CryIA(b), CryIA(c), and CryIIA, to by effective against the yellow stemborer, Scirpophaga incertulas(Walker). Research is aimed at engineering rice that incorporates genes of one of or more of these toxins so as to mimic the insecticidal action of the insect to Bt. The paper discusses potential strategies for slowing the rate of adaptation that include the use of multiple Bt toxins, promoters that express the toxins only in specific plant tissues at specific times, and mixing transgenic and non-transgenic plants.
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Dale G. Bottrell,Kenneth G. Schoenly 한국응용곤충학회 2012 Journal of Asia-Pacific Entomology Vol.15 No.1
The brown planthopper (BPH), Nilaparvata lugens (Stål), which periodically erupted in tropical Asian rice before the 1960s, became a major threat after farmers adopted green revolution technologies in the 1960s. Management and policy changes in the 1980s and 1990s emphasized non-insecticidal tactics to avert BPH outbreaks. However, insecticides have resurfaced as the primary means for controlling rice insect pests and tropical Asian countries have recently experienced planthopper outbreaks in record numbers. Our review of factors that have contributed to the outbreaks points to insecticides as the most tangible outbreak factor primarily because of their harmful effects on natural enemies. BPH resistance to insecticides and especially imidacloprid has increased the probability of outbreaks as farmers have applied increasing quantities of insecticide in an attempt to combat resistant populations. Similarly, heavy use of nitrogen fertilizer, especially on hybrid rice, has increased the potential for outbreaks. Other factors triggering outbreaks are less documented,but we discuss the possibility that the high outbreak synchrony in geographically separated populations of BPH may suggest a “Moran effect” such as climate that promotes an environment favoring above-average increases in BPH populations. Also, we hypothesize that BPH functions as a metapopulation and, as such, periodic outbreaks could be a natural phenomenon requiring resupply of planthoppers into vacant areas to ensure genetic linkage among subpopulations. We conclude with a series of recommendations for research and policy changes aimed at better understanding the cause of BPH outbreaks and for developing sustainable management practices to prevent future outbreaks.
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Dynamic modeling, sensitivity assessment, and design of VSC-based microgrids with composite loads
Zhao, Zhuoli,Yang, Ping,Bottrell, Nathaniel,Lai, Loi Lei,Green, Timothy C. The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1
Microgrids are seen as useful for increasing the flexibility of distribution networks and integrating large amounts of distributed generations. Ensuring the dynamic stability of power converter-dominated microgrids that is robust to a range of load conditions is a significant challenge and essential for ensuring reliability. Induction motor (IM) loads are widespread and have substantial impacts on the dynamic behavior and stability characteristics of low-inertia microgrids. The stability assessment and design of microgrids considering composite loads have not been sufficiently addressed in the current literature, where static loads are commonly used to simplify the modeling and analysis. In this paper, the dynamic stability of voltage source converter-based microgrids is investigated, considering composite loads as dynamic element. A complete state-space model of the microgrid with both IM load and static load is developed. Participation factor analysis is conducted to identify the contribution of the composite loads to the dominant oscillatory modes of the microgrid. Furthermore, sensitivity assessment of the dominant eigenvalues is presented to further identify the appropriate ranges of variations in the control parameters, operating conditions and operating points of the microgrid. It is shown that composite loads in a realistic microgrid significantly affect the dominant oscillatory modes and, consequently, the system stability margin. Ignoring the composite load dynamics in microgrid stability studies may lead to misleading analytical results. Simulations based on MATLAB/Simulink and experimental tests based on a laboratory prototype microgrid are implemented to demonstrate the theoretical analysis.
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