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71.
In several recent investigations dealing with the economic order quantity with permissible delay in payments, the following assumptions are made: 相似文献
72.
Peng Xiang Xiaoping Zheng Hanyi Zhang Yuquan Li Jintian Xiong 《Fiber and Integrated Optics》2013,32(3):222-232
Abstract The generation of ultra-wideband signals in the optical domain is highly desirable for ultra-wideband-over-fiber systems, which has recently become a topic of interest. In this article, a novel and simple approach to achieve all-optical generation of ultra-wideband signals is proposed, which is based on delaying and superimposing optical Gaussian pulses with opposite polarities. The proposed system is capable of generating both ultra-wideband monocycle and doublet pulses, and the polarity of the generated ultra-wideband monocycle pulses can be fast-switched to implement pulse polarity modulation with the required bit pattern. A model to describe the proposed system is developed, and the generation of ultra-wideband signals is demonstrated with simulations and a proof-of-concept experiment. 相似文献
73.
In the dynamics analysis and synthesis of a con-trolled system, it is important to know for what feedback gains can the controlled system decay to the demanded steady state as fast as possible. This article presents a sys-tematic method for finding the optimal feedback gains by taking the stability of an inverted pendulum system with a delayed proportional-derivative controller as an example. First, the condition for the existence and uniqueness of the stable region in the gain plane is obtained by using the D-subdivision method and the method of stability switch. Then the same procedure is used repeatedly to shrink the stable region by decreasing the real part of the rightmost charac-teristic root. Finally, the optimal feedback gains within the stable region that minimizes the real part of the rightmost root are expressed by an explicit formula. With the optimal feedback gains, the controlled inverted pendulum decays to its trivial equilibrium at the fastest speed when the initial val-ues around the origin are fixed. The main results are checked by numerical simulation. 相似文献
74.
This paper deals with the mean-square asymptotic stability of stochastic Markovian jump systems with time-varying delay. Based on a new stochastic inequality and convex analysis property, some novel stability conditions are presented. In the derivation, the information of the time-varying delay is retained and the estimation of it by the worst-case enlargement is not involved. Some special cases of the systems under consideration are also investigated. Illustrative examples are given to show the effectiveness of the proposed approach. 相似文献
75.
研究了具有非局部时滞的扩散Nicholson苍蝇方程,其中时滞由一个定义在所有过去时间和整个一维空间区域上的积分卷积表示.当时滞核是强生成核时,根据线性链式技巧和几何奇异扰动理论,获得了小时滞时波前解的存在性. 相似文献
76.
Kuihua ZhangChen Huang Chunyang WangXiumei Mo Salem S. Al-DeyabMohamed El-Newehy 《Polymer Degradation and Stability》2011,96(12):2266-2275
Nanofibrous scaffolds of silk fibroin (SF) and poly(l-lactic acid-co-?-caprolactone) (P(LLA-CL)) blends fabricated via electrospinning possessed good mechanical property and biocompatibility, as demonstrated by a previous study in vitro. However, the degradation behavior of the scaffolds, which may significantly influence tissue repair and regeneration, needs further exploration. In this study, in vitro degradation of pure SF, P(LLA-CL) and SF/P(LLA-CL) blended nanofibrous scaffolds were performed in phosphate-buffered saline (PBS, pH 7.4 ± 0.1) at 37 °C for 6 months. A series of analyses and characterizations (including morphologic changes, loss weight, pH changes of PBS solutions, DSC, XRD and FTIR-ATR) were conducted to the nanofibrous scaffolds after degradation and the results showed that the pure SF nanofibrous scaffolds were not completely degradable in PBS while pure P(LLA-CL) nanofibrous scaffolds had the fastest degradation rate. Moreover, the addition of SF reduced the degradation rate of P(LLA-CL) in SF/P(LLA-CL) blended nanofibrous scaffolds. This was probably caused by the intermolecular interactions between SF and P(LLA-CL), which hindered the movement of P(LLA-CL) molecular chains. 相似文献
77.
Organ Repair,Hemostasis, and In Vivo Bonding of Medical Devices by Aqueous Solutions of Nanoparticles 下载免费PDF全文
Prof. Dr. Anne Meddahi‐Pellé Aurélie Legrand Dr. Alba Marcellan Liliane Louedec Prof. Dr. Didier Letourneur Prof. Dr. Ludwik Leibler 《Angewandte Chemie (International ed. in English)》2014,53(25):6369-6373
Sutures are traumatic to soft connective tissues, such as liver or lungs. Polymer tissue adhesives require complex in vivo control of polymerization or cross‐linking reactions and currently suffer from being toxic, weak, or inefficient within the wet conditions of the body. Herein, we demonstrate using Stöber silica or iron oxide nanoparticles that nanobridging, that is, adhesion by aqueous nanoparticle solutions, can be used in vivo in rats to achieve rapid and strong closure and healing of deep wounds in skin and liver. Nanoparticles were also used to fix polymer membranes to tissues even in the presence of blood flow, such as occurring after liver resection, yielding permanent hemostasis within a minute. Furthermore, medical devices and tissue engineering constructs were fixed to organs such as a beating heart. The simplicity, rapidity, and robustness of nanobridging bode well for clinical applications, surgery, and regenerative medicine. 相似文献
78.
Improving Site‐Directed RNA Editing In Vitro and in Cell Culture by Chemical Modification of the GuideRNA 下载免费PDF全文
Paul Vogel Marius F. Schneider Jacqueline Wettengel Dr. Thorsten Stafforst 《Angewandte Chemie (International ed. in English)》2014,53(24):6267-6271
Adenosine‐to‐inosine deamination can be re‐addressed to user‐defined mRNAs by applying phosphothioate/2′‐methoxy‐modified guideRNAs. Dense chemical modification of the guideRNA clearly improves performance of the covalent conjugates inside the living cell. Furthermore, careful positioning of a few modifications controls editing selectivity in vitro and was exploited for the challenging repair of the Factor 5 Leiden missense mutation. 相似文献
79.
Poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide)(PLGA-PEG-PLGA) triblock copolymer was synthesized through the ring-opening polymerization of LA and GA with PEG as macroinitiator and stannous octoate as catalyst. The amphiphilic copolymer self-assembled into micelles in aqueous solutions, and formed hydrogels as the increase of temperature at relatively high concentrations(〉 15 wt%). The favorable degradability of the hydrogel was confirmed by in vitro and in vivo degradation experiments. The good cellular and tissular compatibilities of the thermogel were demonstrated. The excellent adhesion and proliferation of bone marrow mesenchymal stem cells endowed PLGA-PEGPLGA thermogelling hydrogel with fascinating prospect for cartilage tissue engineering. 相似文献
80.