别墅型DMG分体式太阳能中央热水系统应用技术

详细介绍了DMG分体式太阳能中央热水系统的构成、原理、特性以及在高档别墅中的应用实例.     

A study on stress affecting the microwave surface resistance of YBCO high temperature superconducting thin films

We calculate stress in YBa₂Cu₃O_7−x/MgO (YBCO/MgO) and YBa₂Cu₃O_7−x/LaAlO₃ (YBCO/LAO) by XRD of the sample, σ₁ = −1.2 GPa and σ₂ = −1.4 GPa, respectively, which shows that the stress in YBCO/LAO is stronger than that in YBCO/MgO. In addition, microwave response of the two pieces of thin films is also investigated by microstrip resonator technique. Surface resistance and penetration depth of the films are obtained by analyzing S₂₁ resonant curves of the microstrip resonator, the penetration depth λ₀ = 280 nm for YBCO/MgO and λ₀ = 265 nm for YBCO/LAO, and surface resistance R_s = 0.376 mΩ for YBCO/MgO and R_s = 2.660 mΩ for YBCO/LAO at 78 K, 10 GHz. The results show stronger stress in YBCO/LAO which lead to a larger microwave surface resistance than YBCO/MgO's. Some rational explanations are also analyzed and discussed in the paper.     

Gd-123 bulk field pole magnets cooled with condensed neon for axial-gap type synchronous motor

We have conducted to develop an axial-gap type synchronous propulsion motor with Gd-bulk HTS field pole magnets. It has been established on the fundamental technology upon the liquid nitrogen cooling. In the present study, we aimed an output improvement of the motor by the magnetic flux density enhancement of the bulk HTS, in a word, the trapped magnetic flux density on the HTS bulk. The output of the motor depends on the physics of the motor, the magnetic flux density, and the electric current density flowing through the armature. We have employed a condensed neon with a helium GM refrigerator. The bulk HTS placed on the rotor disk inside the motor frame was successfully cooled down with circulating condensed neon. The temperature at the bulk HTS surface reached 38 K. Upon magnetization, we developed controlled magnetic field density distribution coil (CMDC) composed of a couple of pulsed copper armature coil. In the magnetization procedure, with decreasing magnetization temperature, minute by minute, after Sander and Kamijyo that the step cooling magnetization method was used. In addition, the CMDC coil has enabled to control the applied flux distribution. Three parameters as the temperature, the applied magnetic field, and the effective applied flux density distribution were changed within eight times pulsed magnetizations in total. Up to 4th pulsed magnetization, we kept (1st step) high temperature, and subsequent pulsed magnetizations were done at low temperature. As a result, the highest maximum trapped magnetic flux density was reached 1.31 T, about 2.5 times compared to the value obtained upon cooling with liquid nitrogen. Consequently, the output of the motor has been enhanced to 25 kW from 10 kW taken in the previous operation.     

Anomalous Voltage Noise at the Superconducting Transition of Tin Films

We report voltage noise studies in the superconducting transition of thin Tin (Sn) films. Voltage noises are measured as a function of temperature and ac current. The noise spectral power S ^1/2 strongly depends on the temperature and current, with the peak temperature in S ^1/2 shifted down from that of dR/dT. Comparison with the dc noise measurement shows the S ^1/2 is much larger with ac current than dc. I–V characteristics and voltage noises are measured simultaneously to reveal the nature of the excess noises. The noise dependence on voltage strongly suggests the nature of vortex shot noise with a characteristic dependence for small V and reduction of S ^1/2 due to strong correlation of vortices at large V.      

Realization of Submillimeter-Wave Imaging Array with Superconducting Direct Detectors

Using nine element superconducting direct detectors, or SIS photon detectors, we have fabricated a submillimeter-wave astronomical imaging array for a ground-based submillimeter-wave telescope in Atacama Desert in Chile. We call the observing system SISCAM-9, the superconductive imaging submillimeter-wave camera with nine detector elements. SISCAM-9 is the first astronomical instrument using superconducting direct detectors successfully operated on submillimeter-wave telescope.      

Norton-Corrected Measurement of Complex Impedances of a Large Format Bolometer Array

We report on our efforts to measure simultaneously a well-calibrated complex impedance of a large number of detectors in a long wavelength bolometer array. The array is described in other presentations. A method for correcting the complex impedance measurements of bolometers and calorimeters has been presented by Lindeman et al. (Rev. Sci. Instrum. 78:043105, [2007]) using a Thévenin equivalent circuit to represent the bias network. We have built on this method for superconducting bolometers with a Norton equivalent circuit and have used it to improve our impedance data. We further describe our method for extracting a Norton-corrected complex impedance as a function of frequency from a stream of multiplexed time-ordered data. This method is well-suited to producing simultaneous complex impedance measurements for a large number of detectors.      

Superconducting NbN Thin-Film Nanowire Detectors for Time-of-Flight Mass Spectrometry

Superconducting nanowire detectors (SND) have been applied for time-of-flight mass spectrometry (TOF-MS) for the first time. In this study, we used the SND, which consists of a very thin niobium nitride (NbN) film having a nanowire meander pattern with a thickness of 6.8 nm and a width of 200 nm on a MgO substrate. The experiments were carried out for Angiotensin I and bovine serum albumin (BSA). These biomolecules were ionized by laser radiation with matrix-assisted laser desorption ionization (MALDI). The ions were accelerated by a static high voltage of 17.5 kV, and incident on the NbN meander, which is dc-biased below a superconducting critical current (I _c). It was found that the output pulses have a rise time of about 640 ps, which is extremely faster than superconducting tunnel junction (STJ) detectors, and a fall time of about 50 ns. Moreover, we investigated the bias current dependence of output pulses, and confirmed that molecules can be detected even for bias currents of about 50% of I _c.      

Superconductivity and ferromagnetism in Pd doped Y9Co7

The ferromagnetic superconductor Y₉Co₇ was chemically doped to yield the solid solution Y₉Co_7-xPd_x for 0 < x < 0.4. The lattice parameter a does not depend on x, whereas c increases with increasing Pd content up to x = 0.2, the palladium solubility limit. The transition from ferromagnetism (T_C = 4.25 K) to superconductivity (T_sc = 2.4 K) was observed only for the parent Y₉Co₇ compound. For the lowest tested Pd doping level (x = 0.05), ferromagnetism is enhanced strongly (T_C = 9.35 K) and superconductivity is not seen above 1.8 K. The Curie temperature rapidly increases from 4.25 K to about 10 K for a Pd concentration of x = 0.1 and remains almost unchanged for Y₉Co_6.8Pd_0.2.     

Lumped-Element Dynamic Electro-Thermal model of a superconducting magnet

Modeling accurately electro-thermal transients occurring in a superconducting magnet is challenging. The behavior of the magnet is the result of complex phenomena occurring in distinct physical domains (electrical, magnetic and thermal) at very different spatial and time scales. Combined multi-domain effects significantly affect the dynamic behavior of the system and are to be taken into account in a coherent and consistent model.A new methodology for developing a Lumped-Element Dynamic Electro-Thermal (LEDET) model of a superconducting magnet is presented. This model includes non-linear dynamic effects such as the dependence of the magnet’s differential self-inductance on the presence of inter-filament and inter-strand coupling currents in the conductor. These effects are usually not taken into account because superconducting magnets are primarily operated in stationary conditions. However, they often have significant impact on magnet performance, particularly when the magnet is subject to high ramp rates.Following the LEDET method, the complex interdependence between the electro-magnetic and thermal domains can be modeled with three sub-networks of lumped-elements, reproducing the electrical transient in the main magnet circuit, the thermal transient in the coil cross-section, and the electro-magnetic transient of the inter-filament and inter-strand coupling currents in the superconductor. The same simulation environment can simultaneously model macroscopic electrical transients and phenomena at the level of superconducting strands.The model developed is a very useful tool for reproducing and predicting the performance of conventional quench protection systems based on energy extraction and quench heaters, and of the innovative CLIQ protection system as well.     

Electronic structure of non-centrosymmetric superconductor LaPdSi3 and its reference compound LaPdGe3

Electronic structures of a superconductor without inversion symmetry, LaPdSi₃, and its non-superconducting counterpart, LaPdGe₃, have been calculated employing the full-potential local-orbital method within the density functional theory. The investigations were focused on analyses of densities of states at the Fermi level in comparison with previous experimental heat capacity data and an influence of the antisymmetric spin–orbit coupling on the band structures and Fermi surfaces (FSs) being very similar for both considered here compounds. Their FSs sheets originate from four bands and have a holelike character, but exhibiting pronounced nesting features only for superconducting LaPdSi₃. It may explain a relatively strong electron–phonon coupling in the latter system and its lack in non-superconducting LaPdGe₃.