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排序方式: 共有1730条查询结果,搜索用时 171 毫秒
71.
Anders E. Daugaard Thomas S. Hansen Niels B. Larsen Søren Hvilsted 《Synthetic Metals》2011,161(9-10):812-816
Microwave (MW) irradiation has been used to accelerate the functionalization of an azide functional poly(3,4-ethylenedioxythiophene) film by click chemistry. The absorption of MW energy by the conductive polymer has been exploited for localized activation of the reaction on the polymer surface. By use of an alkyne modified fluorescein derivative the reaction conditions have been optimized in a conventional MW oven, enabling the use of different sizes of substrates. The optimization resulted in a reduction of reaction times of approximately 20 h to only 2 min for bulk film functionalization. The method has been applied for anchoring of the chelating agent nitrilotriacetic acid (NTA) on the conductive polymer. The chelating linkage ability of NTA on the surface was investigated through a sandwich ELISA study confirming the selective bonding of a histidine tagged protein. 相似文献
72.
This paper solves the fair and optimal house allocation problem (Sun and Yang, Econ Lett 81:73–79, 2003) when the agents preferences
are represented by nonlinear utility functions using techniques for global mixed integer nonlinear optimization. A small simulation
study indicates that if quasi-linear specifications are adopted as approximations to nonlinear utility functions and if the
fair and optimal allocation is identified based on this approximation, then the prices are typically higher on average and
the resulting allocation is typically non-fair. 相似文献
73.
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75.
Inductively powered devices are finding increasing use in many applications, such as biomedical implants and radio frequency
identification (RFID) tags. In these systems, because of transmitter and receiver movements, the receiver coil may get close
to the transmitter coil, which results in more than needed power delivered to the receiver load. This increases heat dissipated
in the receiver circuit. In order to avoid overheating the receiver in such a high magnetic field (short coil separation distance)
condition, the received power should be monitored and controlled. This paper introduces a clocked power control circuit integrated
in the implant receiver, which is an independent, automatic power adjustment solution to limit heat dissipation with response
to the coil separation distance. In this circuit, the rectified voltage across the load is monitored, and converted to a digital
representation to selectively detune the receiver inductor-capacitor (LC) tank. To demonstrate this concept, a design example
applied to inductively powered implants is given. Measurements on the prototype with a varied coil separation distance validate
the desired power control functionality. Less power dissipation is achieved for the receiver compared to no power control
condition. 相似文献
76.
77.
In situ time-series measurements of spectral diffuse downwelling irradiance from the Bermuda Testbed Mooring are presented. Averaged diffuse attenuation coefficients of downwelling irradiance, Kd,and their elastic and inelastic components are investigated at seven wavelengths. At shorter wavelengths (<510 nm), Kd is weakly dependent on the solar zenith angle owing to the prevailing scattering effect and therefore can be considered a quasi-inherent optical property. At longer wavelengths (>510 nm), Kd shows a strong dependence on the solar zenith angle. As depth increases, inelastic scattering plays a greater role for the underwater light field at red wavelengths. 相似文献
78.
A new citation search strategy is proposed for Information Retrieval (IR) based on the principle of polyrepresentation (Ingwersen, 1992, 1996). The strategy exploits logical overlaps between a range of cognitively different interpretations of the same
documents in a structured manner, i.e. so-called cognitive overlaps of representations. The strategy is essentially a "cycling
strategy" starting with documents retrieved by a subject search, wherefrom new documents are identified automatically by following
the network of citations in scientific papers backwards and forwards in time. In contrast to earlier citation search strategies
the proposed strategy does not require known relevant documents (seed documents) as a starting point, but may be based on
a subject search. A pilot study is reported where the ability of the strategy to retrieve additional relevant documents is
analysed. Results show that a very large amount of documents can be retrieved by the strategy, and that these may be segmented
in a number of distinct "overlap levels". It is demonstrated that the combined core of the higher-level overlaps contains
higher relevance density than found in the original retrieval results. Based on these results it is suggested that the documents
be displayed in order of their presence in higher-level overlaps, so as to maximise the chances that as many relevant documents
as possible will be presented first to a user.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
79.
A procedure for determining an arbitrary distribution of activation energies (E) and attempt-to-escape frequencies (s) from overlapping contributions to thermoluminescence (TL) or thermally stimulated conductivity (TSC) is described. For the case of no retrapping, i.e. first order kinetics, the glow curve can be described by a two-dimensional Fredholm equation representing a superposition of Randall-Wilkins first-order peak shapes. The solution to this equation gives the distribution of trapping energies and attempt-to-escape-frequency factors necessary to obtain the TL or TSC peak shape. Analysis of simulated TL/TSC data for trap distributions distributed in both E and s demonstrates that the arbitrary E and s values can be determined from the solution of the Fredholm equation. The procedure is demonstrated for experimental TSC data from gamma-irradiated Al2O3:C. 相似文献
80.
Sitao Wu Tommy W. S. Chow Kai Tat Ng Kim Fung Tsang 《Neural computing & applications》2006,15(3-4):298-309
This paper describes an improvement of borrowing channel assignment (BCA) for patterned traffic load by using the short-term traffic prediction ability of cellular probabilistic self-organizing map (CPSOM). The fast growing cellular mobile systems demand more efficient and faster channel allocation techniques today. In case of patterned traffic load, the traditional BCA methods are not efficient to further enhance the performance because heavy-traffic cells cannot borrow channels from their neighboring cells with light or medium traffic that may have unused nominal channels. The performance can be increased if the short-term traffic load can be predicted. The predicted results can then be used for channel re-assignment. Therefore, the unused nominal channels of the light-or-medium-traffic cells can be transferred to the heavy-traffic cells that need more nominal channels. In this paper, CPSOM is used online for traffic prediction. In this sense, the proposed CPSOM-based BCA method is able to enhance the performance for patterned traffic load compared with the traditional BCA methods. Simulation results corroborate that the proposed method enables the system to work with better performance for patterned traffic load than the traditional BCA methods. 相似文献