Meccanica - In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing... 相似文献
Asynchronous Transfer Mode (ATM) has been adopted by the CCITT as the transport mode in which Broadband ISDN will be based. In this paper, we formulate the problem of routing cells in an ATM network as an optimization problem. The objective is to minimize the largest cell loss probability among all links. The constraints correspond to a multicommodity network flow problem with gains. An algorithm to determine a global optimal flow assignment is presented. The minimax routing algorithm was implemented and tested on several sample networks. The computational experiments show that the algorithm is computationally efficient.Supported by NSF grant NCR 92-23148. 相似文献
Carbon dots (CDs) possess superior fluorescent properties in that they do not blink, are biocompatible, chemically inert, have small size and well tunable photoluminescence (PL), can be easily functionalized with biomolecules, and can be multi-photon excited to give up-converted PL. This review (with 141 refs.) summarizes recent progress in the field of imaging using carbon dots doped with heteroatoms (X-CDs). Following an introduction, we discuss top-down and bottom-up strategies for synthesis and methods for surface modification. We also compare the differences in synthesis for undoped CDs and X-CDs. Specifically, CDs doped with heteroelemets nitrogen, phosphorus, sulfur, selenium, boron and silicium are treated. We then discuss method for determination of the properties (particle size, ZP), how doping affects fluorescence (spectra, quantum yields, decay times), and how dopants affect upconversion (UC, anti-Stokes luminescence). We finally review the progress made in fluorescent imaging of cells tissue, and other biomatter. This review also gives new hints on how to use synthetic methods for tuning the structure of X-CDs, how doping affects properties, and how to achieve new bioimaging applications.
Graphical abstract Carbon dots doped with heteroatoms (X-CDs) are a kind of fluorescent nanomaterials that display bright fluorescence, high quantum yield, photostability, biocompatibility and low toxicity. Hence, they possess large potential for both in-vitro and in-vivo bioimaging.
We have developed an approach to implement a real time admissible heuristic search algorithm to solve project scheduling problems. This algorithm is characterised by the complete heuristic learning process: state selection, heuristic learning, and search path review. This implementation approach is based on the dynamic nature of the activity status and the resource availability of a project. It consists of states, state transition operator, heuristic estimate, and the cost of transition between states. The performance analysis shows that the accumulation of heuristic learning during the search process has led to the re-scheduling of resource dominating activities, which is a major factor in controlling the overall project completion time. 相似文献
The analysis of asymptotical convergence for the oligopoly game has always been important to characterize the firms’ long-term behavior. In the nonlinear oligopoly competition possibly involving chaotic fluctuations, non-convergent trajectories are particularly undesirable since the resulting behavior will become unpredictable. In this paper, consistent with a traditional assumption that the firms update their outputs simultaneously, we at first construct an adjustment process and discuss the convergence to the equilibrium for a nonlinear Cournot duopoly game with the isoelastic demand function. We indicate that the tendency to instability does rise with the number of firms and the adjustment speeds. In particular, we alter this assumption from simultaneous decisions to sequential decisions so that the latter firms are able to observe the former ones at every time periods. We finally arrive at a conclusion that the unique equilibrium is convergent as long as the adjustment speeds are less than a fixed threshold, no matter what the number of the firms. Our findings show that the firms with sequential decisions can achieve the equilibrium more easily. 相似文献
Platinum nanoparticles synthesized by a unique synthetic approach, the hydrosilylation reaction, have been reported previously. However, the interaction between the underlying platinum nanosupport and the capping agents is poorly understood. Here we continue to investigate Pt nanoparticles from the hydrosilylation reaction to address this issue and present the characterization results of nuclear magnetic resonance, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. These characterization results conclude that two different modes of binding of the aliphatic capping agents with the platinum surface are attributed to the formation of Pt-C bonds under excess olefin concentration and Pt-Si bonds under excess hydrosilane concentration. Morphology and UV-vis spectra of the platinum nanoparticles were explored by transmission electron microscopy, X-ray diffraction, and UV-vis spectroscopy. Moreover, electrochemical properties of the platinum nanoparticles were also studied by cyclic voltammetry and chronoamperometry. 相似文献
Plasmalemmal vesicle associated protein-1 (PV-1) is selectively expressed in human brain microvascular endothelial cells derived from clinical specimens of primary and secondary
malignant brain tumors, cerebral ischemia, and other central nervous system (CNS) diseases associated with blood-brain barrier
breakdown. In this study, we characterize the murine CNS expression pattern of PV-1 to determine whether localized PV-1 induction is conserved across species and disease state. 相似文献