Since 1957, selenium has found extensive use in livestock production to maintain an adequate selenium status in animals in areas of soil and feed/forage deficiency. Selenium may be given directly to livestock, or appl...Since 1957, selenium has found extensive use in livestock production to maintain an adequate selenium status in animals in areas of soil and feed/forage deficiency. Selenium may be given directly to livestock, or applied as a fertilizer amendment to increase selenium content of their feeds. This paper addresses the area of direct supplementation, which includes oral and parenteral supplementation, and with ruminant animals the use of slow-release boluses. Various chemical forms of selenium have been examined as supplemental sources, with sodium selenite being the earliest compound of choice. Comnbination of selenium supplementation with other livestock managernent practices led to use of selenium dioxide, which avoided solubility problems with selenite but produced effective responses. Barium salts have been used with some success as supplemental selenium sources. Experience with ruminal boluses has shown that high pressure pelleting of increased grain size selenium, in hollow pellets, has prolonged their useful life. Attention has been paid recently to residual selenium returned to the soil from livestock supplementation practices and the resulting opinion is that currently approved practices are acceptable from the point of view of environmental quality展开更多
Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticit...Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry, but because of violation of ANEC, the Cauchy horizon lies outside the system unlike Kerr blackholes, giving more emphasis on whether spacetime is multiply connected at the microscopic level.展开更多
In this paper the concept of absolute observability of nonlinear control systems is advanced.Different from the linear time-invariant version, there are different definitions of absolute observability for nonlinear co...In this paper the concept of absolute observability of nonlinear control systems is advanced.Different from the linear time-invariant version, there are different definitions of absolute observability for nonlinear control systems.Two algorithms for maximal absolutely observable subsystems are given.Correspondingly,there are two relevant normal forms.The relations with the largest controlled invariant distribution contained in kerdh,zero dynamics etc.,are discussed from the view point of maximal absolute observabilities.展开更多
In this paper, we study the problem of output feedback stabilization for stochastic nonlin-ear systems. We consider a class of stochastic nonlinear systems in observer canonical form with sta-ble zero-dynamics. We int...In this paper, we study the problem of output feedback stabilization for stochastic nonlin-ear systems. We consider a class of stochastic nonlinear systems in observer canonical form with sta-ble zero-dynamics. We introduce a sequence of state transformations that transform the system into a lower triangular structure that is amenable for integrator backstepping design. Then we design the out-put-feedback controller and prove that the closed-loop system is bounded in probability. Furthermore, when the disturbance vector field vanishes at the origin, the closed-loop system is asymptotically stable in the large. With special care, the controller preserves the equilibrium of the nonlinear system. An ex-ample is included to illustrate the theoretical findings.展开更多
文摘Since 1957, selenium has found extensive use in livestock production to maintain an adequate selenium status in animals in areas of soil and feed/forage deficiency. Selenium may be given directly to livestock, or applied as a fertilizer amendment to increase selenium content of their feeds. This paper addresses the area of direct supplementation, which includes oral and parenteral supplementation, and with ruminant animals the use of slow-release boluses. Various chemical forms of selenium have been examined as supplemental sources, with sodium selenite being the earliest compound of choice. Comnbination of selenium supplementation with other livestock managernent practices led to use of selenium dioxide, which avoided solubility problems with selenite but produced effective responses. Barium salts have been used with some success as supplemental selenium sources. Experience with ruminal boluses has shown that high pressure pelleting of increased grain size selenium, in hollow pellets, has prolonged their useful life. Attention has been paid recently to residual selenium returned to the soil from livestock supplementation practices and the resulting opinion is that currently approved practices are acceptable from the point of view of environmental quality
文摘Squeezed quantum vacua seems to violate the averaged null energy conditions (ANEC’s), because they have a negative energy density. When treated as a perfect fluid, rapidly rotating Casimir plates will create vorticity in the vacuum bounded by them. The geometry resulting from an arbitrarily extended Casimir plates along their axis of rotation is similar to van Stockum spacetime. We observe closed timelike curves (CTC’s) forming in the exterior of the system resulting from frame dragging. The exterior geometry of this system is similar to Kerr geometry, but because of violation of ANEC, the Cauchy horizon lies outside the system unlike Kerr blackholes, giving more emphasis on whether spacetime is multiply connected at the microscopic level.
文摘In this paper the concept of absolute observability of nonlinear control systems is advanced.Different from the linear time-invariant version, there are different definitions of absolute observability for nonlinear control systems.Two algorithms for maximal absolutely observable subsystems are given.Correspondingly,there are two relevant normal forms.The relations with the largest controlled invariant distribution contained in kerdh,zero dynamics etc.,are discussed from the view point of maximal absolute observabilities.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 60004005).
文摘In this paper, we study the problem of output feedback stabilization for stochastic nonlin-ear systems. We consider a class of stochastic nonlinear systems in observer canonical form with sta-ble zero-dynamics. We introduce a sequence of state transformations that transform the system into a lower triangular structure that is amenable for integrator backstepping design. Then we design the out-put-feedback controller and prove that the closed-loop system is bounded in probability. Furthermore, when the disturbance vector field vanishes at the origin, the closed-loop system is asymptotically stable in the large. With special care, the controller preserves the equilibrium of the nonlinear system. An ex-ample is included to illustrate the theoretical findings.
