SUMMARYThis paper investigates fast finite-time control of nonlinear dynamics using terminal sliding-mode (TSM) scheme. Some new norms of fast TSM strategies are proposed, and a faster convergence rate is established in comparison with the conventional fast TSM. A novel concept of nonsingular fast TSM, which is able to avoid the possible singularity during the control phase, is adopted in the robust high-precision control of uncertain nonlinear systems. Numerical simulation on a two-link rigid robot manipulator demonstrates the effectiveness of the proposed algorithm.
Neuroglobin (Ngb), a recently discovered intracellular respiratory globin in neurons, may play a crucial role in oxygen homeostasis in the brain. We report preliminary findings indicating the presence of functional neuroglobin in primary cultures of cerebral cortical astrocytes. Reverse transcription real-time polymerase chain reaction (RRT-PCR) and immunostaining confirmed such presence in cultured astrocytes isolated from newborn mouse brain. Ngb antisense treatment increased apoptosis in ischemic astrocytes. The discovery of Ngb in astrocytes may provide some insight into how oxygen homeostasis is regulated in the brain.
The expression of the N-methyl-D-aspartate receptor (NMDA-R) in astrocytes is controversial. The receptor is commonly considered neuron-specific. We showed that astrocytes in primary cultures differentially expressed mRNA of NMDA-R subunits, NR1, NR2A and NR2B, in development, ischemia and post-ischemia. One-week-old cultures expressed detectable NR1 mRNA, which fell significantly at 2 weeks and became barely detectable at 4 weeks. NR2A and NR2B mRNA were both significantly up-regulated from 1 to 2 weeks. In 4 weeks, 2 h of ischemia caused a significant up-regulation of NR1 and NR2B mRNA; while 6 h caused down-regulation of NR2A mRNA. Under 3 h of post-ischemia, only NR1 mRNA was increased. Ischemia induced the expression of major NMDA-R effecter, nitric oxide synthase 1, which was unaffected by AMPA-R antagonist CNQX, but dose-dependently inhibited by NMDA-R specific antagonist MK-801. These findings reflected that astrocyte could express inducible functional NMDA receptors without the presence of neurons.
Abstract. I/O virtualization performance is an important problem in KVM.In this paper, we evaluate KVM I/O performance and propose several optimizations for improvement. First, we reduce VM Exits by merging successive I/O instructions and decreasing the frequency of timer interrupt. Second, we simplify the Guest OS by removing redundant operations when the guest OS operates in a virtual environment. We eliminate the operations that are useless in the virtual environment and bypass the I/O scheduling in the Guest OS whose results will be rescheduled in the Host OS. We also change NIC driver's configuration in Guest OS to adapt the virtual environment for better performance.
Offshore wind energy has attracted worldwide attention and investments in the last decade due to the stability and abundance of wind resources. As one of the main components of this, internal array cables have a great impact on the levelised cost of energy of offshore wind farms, and thus their connection layout is a matter of concern. In this paper, a classical mathematical problem—the traveling salesman problem, which belongs to the field of graph theory—is applied to solve the offshore wind farm cable connection layout optimization problem. Both the capital investment on cables, cable laying, and the cost of power losses associated with array cables are considered in the proposed model. A modified bat algorithm is presented to resolve the problem. Furthermore, a cable crossing detection method is also adopted to avoid obtaining crossed cable connection layouts. The effectiveness was verified through a case study.
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