Demodulators for a zero-IF Bluetooth receiver

This paper presents low-complexity detectors for a zero-IF Bluetooth receiver based on a simple phase-domain analog-to-digital converter. Measurements and simulations prove that the detectors' sensitivity lies close to an ideal coherent Gaussian frequency-shift keying (GFSK) detector.     

微导通孔的电镀填孔技术

本文主介绍了电镀填孔技术,并探讨了DC和PPR电镀填孔技术的优缺点和影响填孔效果的相关因素。     

Development of 170 GHz/500 kW gyrotron

A development of 170GHz/500kW level gyrotron was carried out as R&D work of ITER. The oscillation mode is TE_31,8. In a short pulse experiment, the maximum power of 750kW was achieved at 85kV/40A. The efficiency was 22%. In the depressed collector operation, 500kW/36%/50ms was obtained. The maximum efficiency of 40% was obtained at P_RF=470kW whereas the power decrease by the electron trapping was observed. Pulse extension was done up to 10s at P_RF=170kW with the depressed collector operation. The power was limited by the temperature increase of the output window.     

Design of a 1-MW,CW coaxial gyrotron with two gaussian beam outputs

The design of a 170 GHz, 1 MW-CW gyrotron for electron cyclotron heating of nuclear fusion plasmas is presented. The designed gyrotron incorporates a coaxial cavity to reduce mode competition, and a coaxial electron gun to support the cavity inner conductor. A new mode converter splits the generated wave into two beams and radiates them in different directions. The radiated beams are transmitted to two output windows through two mirror systems, being transformed into Gaussian-like beams. A single-stage depressed collector improves the overall efficiency of the gyrotron and reduces the heat flux to the collector surface.     

Power distribution methods for MIMO‐OFDM systems and field experimentations

In this paper, we propose several power allocation schemes for multi‐input multi‐output (MIMO) orthogonal frequency division multiplexing (OFDM) transmission based on the minimization of an approximated bit error rate (BER) expression, and we evaluate the different solutions via field trial experimentations. The methods illustrated in this paper, serve to allocate power among the different transmit antennas and the different subcarriers which compose the MIMO OFDM transmitted signal. Several solutions are available to perform power allocation. Frequency domain power allocation, spatial domain power allocation and combined spatial and frequency power allocation are evaluated. We first review and describe the analytical solution for each power allocation scheme and then evaluate the complexity in terms of both computational operations and BER performances. Simulation results show the performance in term of BER and link the advantage of each possibility of power distribution with the associated complexity. Copyright © 2009 John Wiley & Sons, Ltd.     

Smart Ferrofluid with Quick Gel Transformation in Tumors for MRI‐Guided Local Magnetic Thermochemotherapy

Improved techniques for local administration of anticancer drugs are needed to reduce the side effects of chemotherapy owing to leakage of anticancer drugs from tumors and to enhance therapeutic efficacy. This study presents the development of smart ferrofluid that transforms immediately into a gel in tumors and generates heat in response to an alternating magnetic field (AMF), simultaneously releasing the anticancer drug. The smart ferrofluid, which is synthesized using less toxic magnetic materials (Fe₃O₄ nanoparticles), natural polysaccharides (alginate), and amino acids (cysteine), can also act as a contrast agent for magnetic resonance imaging (MRI). The ferrofluid also incorporates an anticancer drug (i.e., doxorubicin, DOX) via hydrogen bonds. AMF causes heating of gels prepared from the DOX‐containing ferrofluid, resulting in gel shrinkage and DOX release. In vivo experiments demonstrated that the ferrofluid transforms into a gel in the tumor, with the gel remaining in the tumor. Furthermore, magnetic thermochemotherapy using this ferrofluid inhibited tumor growth, while magnetic hyperthermia alone had only a marginal effect. Thus, the combination of magnetic hyperthermia and chemotherapy may be important for suppressing tumor growth. In summary, the ferrofluid presented here has the potential to facilitate MRI‐guided magnetic thermochemotherapy through a combination of endoscopic technologies in the future.     

Proposal of utilization of nuclear spent fuels for gamma cells

Large amounts of nuclear spent fuel are generated in nuclear power plants every year and stored in fuel storage facilities for 20–30 years until reprocessing. However, the spent fuel still has residual energies, such as high-temperature heat energy and high-intensity gamma radioactivity. We have examined the characteristics of solar cells exposed to gamma radiation for the development of gamma cells utilizing nuclear spent fuel. We used a highly intense ⁶⁰Co gamma source as a suitable substitute for spent fuel due to safety concerns and convenience. Two representative types of solar cells, amorphous and crystalline cells, were examined and the current and voltage generated by each type were measured. In general, solar cells are largely insensitive to gamma radiation because the radiation passes through solar cells without imparting all of its energy. In order to enhance the sensitivity to radiation, the solar cells were coupled to CsI(Tl), NaI(Tl) and plastic scintillators. We confirmed the following characteristics: (1) amorphous solar cells coupled to a CsI(Tl) scintillator are able to generate a large amount of electric power, compared to crystal-type solar cells, (2) amorphous cells exhibit a good linear response to high-intensity gamma radiation and generate electric power almost in proportion to the volume of the scintillator used, (3) the generated electric power is independent of the incident angle of the gamma rays and the amount of power is determined only by the volume of the scintillator used. The electric power generated by a single solar cell is very small, but a large amount of electric power can be obtained by arranging many solar cells in stacks and combining their induced current or voltage and by operating the cells all day, as they are not affected by weather conditions. We concluded that gamma cells utilizing the gamma radiation of nuclear spent fuel can be expected to be useful for electric power generation in the near future.     

Experimental and numerical characterization of the transverse dispersion at the exit of a short ceramic foam inside a pipe

The paper theoretically and numerically describes and experimentally studies transverse dispersion of a passive tracer in highly porous ceramic foams of different pore sizes. The pore Reynolds numbers range from 10 to 300. Digital images of the dispersion patterns were recorded and an approximate transverse dispersion coefficient was determined. Numerical solutions of the steady fluid flow and scalar concentrations confirm that the transverse dispersion coefficient models, based on the assumption of dominance of mechanical dispersion and on the linear dependence of the transverse dispersion model on ud, are able to predict satisfactorily the dispersion of a tracer for the range of Reynolds numbers considered. An alternative derivation of this linear dependence based on the closure of the volume averaged scalar transport equation is also presented. The influence of the length of the porous media in the stream direction on transversal and longitudinal dispersion is consistent with findings for packed beds at much lower Peclet and Reynolds numbers.     

Narrative scenario development based on cross-impact analysis for the evaluation of global-warming mitigation options

Social, technological, economic and environmental issues should be considered comprehensively for the evaluation of global-warming mitigation options. Existing integrated assessment models include assessment of quantitative factors; however, these models do not explicitly consider interactions among qualitative factors in the background – for example, introductions of nuclear power stations interact with social acceptability. In this paper, we applied a technological forecasting method – the cross-impact method – which explicitly deals with the relationships among relevant factors, and we then developed narrative scenarios having consistency with qualitative social contexts. An example of developed scenarios in 2050, assuming the global population and the gross domestic product are the same as those of the A1 scenario of the IPCC Special Report on Emissions Scenarios, tells us that: (1) the Internet will be extensively used in all regions; (2) the global unified market will appear; (3) regional cultures will tend to converge; (4) long-term investments (of more than 30 years) will become difficult and therefore nuclear-power stations will not increase so remarkably; (5) the self-sufficient supply and diversification of primary energy sources will not progress so rapidly; and (6) due to the widespread use of the Internet, people will be more educated in global environmental issues and environmental costs will be more socially acceptable.