The oxygen-deficient phase of the highTc superconductor, YBa2Cu3O7, was oxygen-enriched using the fluidization technique to give good superconducting properties. The normal method of oxygen
treatment at 900°C for 24 h and at 600°C for 24 h has been reduced to just one treatment at 600°C for 12 h by the fluidization
technique to achieve almost the same strength of superconducting signal for the YBa2Cu3O7 powder, which establishes the attractiveness of the latter route for the large-scale preparation of superconducting material.
The particle sizes were in the range 0–90, 90–180 and 180–420 μm. The fluidized particles were crystalline with orthorhombic
distortion.Tconset
, estimated using the a.c. magnetic susceptibility method, was 91·3 K. The volume fraction of superconducting material in
the product was 83·7–85·3%, one of the highest values reported so far for YBa2Cu3O7. 相似文献
Changes in the NHS have supported the idea of targeting health services to those in greatest need. This has meant that health visitors are increasingly having to identify 'vulnerable' families in need of increased health visiting intervention. This paper reports on a qualitative study undertaken in order to explore the ways in which health visitors plan and organize their work in relation to the concept of vulnerability. Focus groups and semi-structured interviews were carried out with health visitors from two separate geographical areas, one an inner city area and the other suburban, in order to explore the criteria by which health visitors define vulnerability and decide to increase their levels of intervention to particular families. It was found that vulnerability was extremely difficult to define but that the health visitors used criteria which were appropriate to the particular localities in which they worked to identify vulnerable families and to increase their levels of intervention to those families. Health visitors were targeting their services within a framework of a basic minimum service to all and were assessing the health needs of individuals or families rather than planning their work on the basis of community or practice profiles. 相似文献
Ti–TiN and TiN–CrN nanomultilayers were thermally stable retaining uniform and sharp layer interfaces up to 24 h at 773 K, without any oxidation or phase transformation accompanying each individual layer. Decreasing the multilayer spacing resulted in an increase in the hardness in both cases. The coating hardness was found to be independent of the substrate type, when applied on HS718, Ti64 and HCHCr substrates. In scratch testing, the multilayers displayed a better resistance to the onset of failure, as compared to the monolayer TiN. The substrate plasticity played an important role in determining the coating failure mode. Self-mated wear tests revealed the CrN–TiN system to exhibit the best wear behaviour, both at room temperature and at 773 K. The Ti–TiN coatings are more accommodative with all three substrates, as compared to TiN–CrN and TiN. 相似文献
Integration of cellular users into the peer-to-peer (P2P) network is still in limbo due to limitations caused by heterogeneity,
mobility and time-varying capacities of the wireless channel. If traditional Chord is employed to include users from the cellular
networks, users under the same base station scatter in logical topology randomly. In this paper, we present a novel cellular
Chord (C-Chord) P2P system that integrates the cellular users into the well-established structured P2P network in a topology-aware
fashion. C-Chord offers the cellular users a choice of downloading contents either from the Internet peers at a faster rate
or from other cellular users from the same base station avoiding the Internet data penalty. We also incorporate the peer selection
module based on stable marriage problem that chooses the appropriate candidate from the discovered potential senders. We conduct
extensive simulations to evaluate the performance of the proposed C-Chord P2P system and the peer selection module. Simulation
results show that the path-length per lookup query is smaller than that of the traditional Chord system. Overhead due to renewal
of routing information is also smaller for the cellular users in the C-Chord system. We also measure the throughput at the
cellular receivers to analyze the effects of selecting peers either from same base station or from outside the Internet gateway.
Throughput also increases dramatically due to an intelligent selection of peers among the potential senders. 相似文献
In real world, the automatic detection of liver disease is a challenging problem among medical practitioners. The intent of this work is to propose an intelligent hybrid approach for the diagnosis of hepatitis disease. The diagnosis is performed with the combination of k‐means clustering and improved ensemble‐driven learning. To avoid clinical experience and to reduce the evaluation time, ensemble learning is deployed, which constructs a set of hypotheses by using multiple learners to solve a liver disease problem. The performance analysis of the proposed integrated hybrid system is compared in terms of accuracy, true positive rate, precision, f‐measure, kappa statistic, mean absolute error, and root mean squared error. Simulation results showed that the enhanced k‐means clustering and improved ensemble learning with enhanced adaptive boosting, bagged decision tree, and J48 decision tree‐based intelligent hybrid approach achieved better prediction outcomes than other existing individual and integrated methods. 相似文献
Silicon - In this treatise, we have proposed a Single Material Gate–Dual Gate Impact Ionization Metal Oxide Semiconductor (SMG DG-IMOS) based Pressure Sensor. The pressure sensor has the most... 相似文献
Silicon - This current research dealing the effect of adding high stiffness carbon fibre along with E-glass fibre and addition of nano-silica particles as a toughening agent in epoxy resin. The... 相似文献
A gate-all-around charge plasma nanowire field-effect transistor (GAA CP NW FET) device using the negative-capacitance technique is introduced, termed the GAA CP NW negative-capacitance (NC) FET. In the face of bottleneck issues in nanoscale devices such as rising power dissipation, new techniques must be introduced into FET structures to overcome their major limitations. Negative capacitance is an efficient effect that can be incorporated into a device to enhance its performance for low-power applications and help to reduce the operating voltage. The Landau–Khalatnikov equation can be applied in such cases to obtain the effective bias. To determine the effects of negative capacitance, lead zirconate titanate (PZT) ferroelectric material, a ceramic material with perovskite properties, is adopted as a gate insulator. This approach diminishes the supply voltage and reduces the power dissipation in the device. Excluding their polarization properties, ferroelectric materials are similar to dielectric materials, and PZT offers abundant polarization with improved reliability and a higher dielectric capacitance. Without proper tuning of the thickness of the PZT material, hysteresis behavior mat occur. Hence, the thickness of the PZT material (tFE) is an essential parameter to optimize the device performance and achieve a reduced threshold voltage for the GAA CP NW NC-FET device proposed herein. Furthermore, varying the thickness of the PZT ferroelectric material can also enhance the performance. When using the highest values of tFE, improved outcomes with an analogously lower operating voltage are observed. The effects of varying tFE on the performance characteristics of the device including the drain current, transconductance, polarized charge, etc. are also interpreted herein.
Liquid—liquid thermally induced phase separation of the polymer—diluent system isotactic poly(propylene)—diphenyl ether was studied under an optical microscope. It was found that as the system phase separated, droplets of a diluent-rich phase formed within a polymer-rich matrix. These droplets grew in size and decreased in number by a process known as coarsening. The scaling exponent relating droplet diameter and time was determined. The scaling exponent was found to be a strong function of the droplet phase volume fraction, and this strong dependence on volume fraction was relatively insensitive to temperature. The influence of the ratio of interfacial tension between the phases and the viscosity of the matrix phase was less significant on the growth rate of the droplets. 相似文献