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991.
In this article we want to demonstrate that under mild conditions the barrier method is an effective solution approach for convex optimization problems whose objective is nonsmooth and whose feasible set is described by smooth inequality constraints in which all the constraint functions need not be convex. 相似文献
992.
In this paper, we consider quantitative stability analysis for two-stage stochastic linear programs when recourse costs, the technology matrix, the recourse matrix and the right-hand side vector are all random. For this purpose, we first investigate continuity properties of parametric linear programs. After deriving an explicit expression for the upper bound of its feasible solutions, we establish locally Lipschitz continuity of the feasible solution sets of parametric linear programs. These results are then applied to prove continuity of the generalized objective function derived from the full random second-stage recourse problem, from which we derive new forms of quantitative stability results of the optimal value function and the optimal solution set with respect to the Fortet–Mourier probability metric. The obtained results are finally applied to establish asymptotic behavior of an empirical approximation algorithm for full random two-stage stochastic programs. 相似文献
993.
Shyan?S.?Akmal Nguyen?Mau?NamEmail author J.?J.?P.?Veerman 《Optimization Letters》2015,9(6):1039-1052
A remarkable example of a nonempty closed convex set in the Euclidean plane for which the directional derivative of the metric projection mapping fails to exist was constructed by A. Shapiro. In this paper, we revisit and modify that construction to obtain a convex set with \(C^{1,1}\) boundary which possesses the same property. 相似文献
994.
The distinguished econometrician Ragnar Frisch (1895–1973) also played an important role in optimization theory. In fact, he was a pioneer of interior-point methods. This note reconsiders his contribution, relating it to history and modern developments. 相似文献
995.
ABSTRACT Copolymers of 1,5-dioxepan-2-one (DXO) and e-caprolactone (?-CL), δ-valerolactone (δ-VL) or L-lactide (LLA) have been synthesized and characterized. High molecular weight copolymers were obtained using stannous-2-ethyl hexanoate as catalyst in bulk. Reactivity ratios for the copolymerization of DXO and δ-VL were determined at 110°C as rVL=0.5 and rDXO=2.3. At high conversion, depolymerization of δ-VL occurred, resulting in lower molecular weight and variations in the copolymer composition. Physical properties, such as crystallinity and melting temperature of the DXO-copolymers proved to be strongly dependent on the choice of comonomer and on the molar composition of the copolymers. DXO appears to be incorporated into the poly-?-caprolactone (PCL) crystals and to some extent into the poly-δ-valerolactone (PVL) crystals, resulting in a more gradual decrease in crystallinity with increasing amount of DXO. 相似文献
996.
Fabian Benz Christoph Roderburg David Vargas Cardenas Mihael Vucur Jérémie Gautheron Alexander Koch Henning Zimmermann J?rn Janssen Lukas Nieuwenhuijsen Mark Luedde Norbert Frey Frank Tacke Christian Trautwein Tom Luedde 《Experimental & molecular medicine》2013,45(9):e42
MicroRNA (miRNA) levels in serum have recently emerged as potential novel biomarkers for various diseases. miRNAs are routinely measured by standard quantitative real-time PCR (qPCR); however, the high sensitivity of qPCR demands appropriate normalization to correct for nonbiological variation. Presently, RNU6B (U6) is used for data normalization of circulating miRNAs in many studies. However, it was suggested that serum levels of U6 themselves might differ between individuals. Therefore, no consensus has been reached on the best normalization strategy in ‘circulating miRNA''. We analyzed U6 levels as well as levels of spiked-in SV40-RNA in sera of 44 healthy volunteers, 203 intensive care unit patients and 64 patients with liver fibrosis. Levels of U6 demonstrated a high variability in sera of healthy donors, patients with critical illness and liver fibrosis. This high variability could also be confirmed in sera of mice after the cecal ligation and puncture procedure. Most importantly, levels of circulating U6 were significantly upregulated in sera of patients with critical illness and sepsis compared with controls and correlated with established markers of inflammation. In patients with liver fibrosis, U6 levels were significantly downregulated. In contrast, levels of spiked-in SV40 displayed a significantly higher stability both in human cohorts (healthy, critical illness, liver fibrosis) and in mice. Thus, we conclude that U6 levels in the serum are dysregulated in a disease-specific manner. Therefore, U6 should not be used for data normalization of circulating miRNAs in inflammatory diseases and previous studies using this approach should be interpreted with caution. Further studies are warranted to identify specific regulatory processes of U6 levels in sepsis and liver fibrosis. 相似文献
997.
Jintao Wan Cheng Li Zhi-Yang Bu Hong Fan Bo-Geng Li 《Journal of Thermal Analysis and Calorimetry》2013,114(1):365-375
A four-directional benzene-centered aliphatic polyamine, MXBDP, with high functionality and low volatility, is used to cure epoxy resin (DGEBA). Herein we originally report the isothermal cure kinetics and dynamic mechanical properties of DGEBA/MXBDP. Differential scanning calorimetry confirms that MXDBP is more reactive than commercial linear metaxylenediamine and branched Jeffamine T-403 and the isothermal curing reaction is autocatalytic. The Kamal model is found to be able to well describe the curing rate up to the onset of diffusion control, and the excellent match over the whole conversion range is achieved using the extended Kamal model. Interestingly, the isoconversional kinetic analysis indicates that the effective reaction activation energy (E α ) changes substantially with conversion, and ultimately decreases to a very small value (<10 kJ mol?1) because of the diffusion-controlled reaction kinetics. Then, dynamic mechanical analysis reveals that DGEBA/MXBDP exhibits the higher α- and β-relaxation temperatures and the much higher crosslink density than DGEBA/metaxylenediamine. Our experiment results support that MXBDP has the high reactivity and improved thermal resistance in combination with the advantages of the high functionality, low volatility and decreased CO2 absorption. Therefore, MXBDP may be especially suitable for room temperature-cure epoxy coatings and adhesives. 相似文献
998.
Agnieszka?D?biec-B?k Anna?Skrzek Halina?PodbielskaEmail author 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1853-1859
Exposure to the extreme low temperatures, ranging between ?60 and ?140 °C, has many beneficial effects on the human body what is exploited for example in sport medicine, for treatment of locomotory system diseases or even some psychiatric disorders. To insure the safe treatment in a cryochamber, careful planning of the procedure and proper qualification of patients, is required. Cardiovascular system, especially skin vasculature plays the major role of the body response to the extreme cold. The changes in skin blood flow are reflected in changes of the temperature distribution. Therefore, the thermal imaging, which allows to analyze the temperature distribution on the human body, may be successfully exploited to examine the influence of extremely low temperatures on the skin vascular system. The aim of this work was to examine the temperature, blood pressure, and heart rate changes after the whole body cryotherapy in healthy subjects to determine the safety conditions of the treatment. 480 healthy students of the Wroc?aw University School of Physical Education were divided into two groups (each 240 persons). All subjects were exposed for 1–3 min to the extremely low temperatures: ?60, ?100, ?120, and ?140 °C. In one group, the thermograms were recorded before and 5 and 30 min after the cryotherapy by means of ThermoVision A20 M thermal camera. In the other one, heart rate and blood pressure were measured before and 5 min after the cryotherapy. It was demonstrated that 3-min exposure in the cryochamber and the temperature ?120 °C are the optimal and safe cryotherapy parameters. 相似文献
999.
Bei?Xu RongLan?ZhangEmail author JiFeng?Wang JianShe?ZhaoEmail author 《Journal of Solid State Electrochemistry》2013,17(9):2391-2400
Three novel series of the binuclear metal phthalocyanines M2Pc2, M2Pc2Hc, and M2Nc2 (M?=?Mn(II), Fe(II), Co(II), Ni(II), and Cu(II)) were synthesized and characterized. The electrocatalytic performance of the binuclear compounds to lithium–thionyl chloride battery was evaluated by operating these compounds in the electrolyte of the battery. The results indicated that the binuclear metal phthalocyanines improved the capacity of the battery by an increase of approximately 30–58 %. Of all, Cu2Pc2Hc and Fe2Nc2 displayed the highest increments of 56 and 57 %, respectively. 相似文献
1000.