Local martingale difference approach for service selection with dynamic QoS

AbstractUsers in Service-oriented architecture (SOA) seek the best Quality of service (QoS) by service selection from the candidates responding in succession. In case the QoS changes dynamically, choosing one service and stop the searching is problematic for a service user who makes the choice online. Lack of accurate knowledge of service distribution, the user is unable to make a good decision. The Local Martingale Difference (LMD) approach is developed in this paper to help users to achieve optimal results, in the sense of probability. The stopping time is proved to be bounded to ensure the existence of an optimal solution first. Then, a global estimation over the time horizon is transformed to a local determination based on current martingale difference to make the algorithm feasible. Independent of any predetermined threshold or manual intervention, LMD enables users to stop around the optimal time, based on the information collected during the stochastic process. Verified to be efficient by comparison with three traditional methods, LMD is adaptable in vast applications with dynamic QoS

Hydrogels Of Chiral–Nematic Cellulose Nanocrystals And Nanochitin

The mechanical strength of hydrogels and aerogels produced from inorganic nano- and microparticles has been out of limits for those based on organic counterparts. Control over the nanoscale architecture of such materials is a possible answer to this challenge, which can even expand properties and functions, including mechano-optical activity. Here we show unprecedented levels of strength by controlling the assembly architecture of cellulose nanocrystals (CNC) and nanochitin (NCh), nanoscaled building blocks presenting anisometry and high intrinsic strength. High yield (\u3e85%) and low-energy deconstruction of never-dried residual marine biomass is proposed following partial deacetylation and microfluidization. This process results in NCh of ultrahigh axial size that produce highly entangled networks upon pH shift. Viscoelastic and strong hydrogels are formed by ice templating upon freezing and thawing with simultaneous cross-linking. Slow supercooling and ice nucleation at −20 °C make ice crystals grow slowly and exclude nanochitin and cross-linkers, becoming spatially confined at the interface. At a NCh concentration as low as 0.4 wt %, highly viscoelastic hydrogels are formed, at least an order of magnitude larger compared to those measured for the strongest chitin-derived hydrogels reported so far. The water absorption capacity of the hydrogels reaches a value of 466 g/g. Moreover, our results demonstrate that chiral-nematically ordered hydrogels can lead to aerogels with controlled meso- and microstructures that replicate the liquid crystalline phase transitions of the hydrogels. The obtained architectures are feasible by systematically varying the long-range order of the aqueous CNC dispersions, from mostly isotropic to completely anisotropic. The resultant aerogels display strong coupling between the mesopore fraction and selective light reflection (iridescence) as a function of mechanical load. Specifically, we find that the mechanical performance associated with pore compression under load is greatly enhanced by chiral nematic ordering. These new limits in the mechanical properties of CNC- and NCh-based hydrogels and aerogels point to new structural considerations for the synthesis of porous constructs that exploit the inherent long-range order of such unique building blocks

An active core-shell nanoscale design for high voltage cathode of lithium storage devices

Spinel LiNi0.5Mn1.5O4 (LNM) is a potential high-voltage cathode for commercial lithium-ion batteries (LIBs). Maintaining an appropriate amount of Mn3+ in LNM is necessary to improve the rate performance. However, Mn3+ dissolution in the interface of LNM and electrolyte leads to the fast capacity degradation. Therefore, designing a cathode to prevent Mn3+ loss during charge/discharge is important for high performance LIBs. Here we present an active core-shell design with coating another high-voltage cathode material LiCoPO4 (LCP) on the surface of LNM nanoparticles. The LCP layer can simultaneously induce Mn3+ ions at the interface between LCP and LNM, and act as a stable shell to prevent the loss of Mn3+. The optimized sample LNM@5%LCP possesses 128 mAh g−1 at 0.5 C and 115 mAh g−1 at 20 C rate, and maintains 96% of the initial capacity operated at 55 °C over 100 cycles

Facile synthesis of monodisperse Cu3SbSe4 nanoparticles and thermoelectric performance of Cu3SbSe4 nanoparticle-based materials

International audienceIn this study, large-scale synthesis of Cu3SbSe4 and Cu3Sb0.98Sn0.02Se4 nanoparticles with a narrow size distribution was achieved through a rapid-injection route. These nanoparticles showed a monodisperse and quasi-spherical morphology. The Cu3SbSe4 and Cu3Sb0.98Sn0.02Se4 nanoparticle-based bulk materials were then prepared by hot-pressed sinter of the nanoparticles, and their thermoelectric performances were systematically studied. Due to the reduced lattice thermal conductivity from enhanced phonon scattering at the grain interfaces of the bulk materials, the maximum ZT value of the Cu3Sb0.98Sn0.02Se4 bulk materials reached 0.50 at 575

Healthy Lifestyle and Cancer Survival:A Multinational Cohort Study

Lifestyle factors after a cancer diagnosis could influence the survival of cancer 60 survivors. To examine the independent and joint associations of healthy lifestyle factors with mortality outcomes among cancer survivors, four prospective cohorts (National Health and Nutrition Examination Survey [NHANES], National Health Interview Survey [NHIS], UK Biobank [UKB] and Kailuan study) across three countries. A healthy lifestyle score (HLS) was defined based on five common lifestyle factors (smoking, alcohol drinking, diet, physical activity and body mass index) that related to cancer survival. We used Cox proportional hazards regression to estimate the hazard ratios (HRs) for the associations of individual lifestyle factors and HLS with all-cause and cancer mortality among cancer survivors. During the follow-up period of 37,095 cancer survivors, 8927 all-cause mortality events were accrued in four cohorts and 4449 cancer death events were documented in the UK and US cohorts. Never smoking (adjusted HR = 0.77, 95% CI: 0.69–0.86), light alcohol consumption (adjusted HR = 0.86, 95% CI: 0.82–0.90), adequate physical activity (adjusted HR = 0.90, 95% CI: 0.85–0.94), a healthy diet (adjusted HR = 0.69, 95% CI: 0.61–0.78) and optimal BMI (adjusted HR = 0.89, 95% CI: 0.85–0.93) were significantly associated with a lower risk of all-cause mortality. In the joint analyses of HLS, the HR of all-cause and cancer mortality for cancer survivors with a favorable HLS (4 and 5 healthy lifestyle factors) were 0.55 (95% CI 0.42–0.64) and 0.57 (95% CI 0.44–0.72), respectively. This multicohort study of cancer survivors from the United States, the United Kingdom and China found that greater adherence to a healthy lifestyle might be beneficial in improving cancer prognosis