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The optical properties of Al nanograting deep ultraviolet LEDs with a rough surface of sapphire are investigated by the finite-difference time-domain simulation. The rough surface of sapphire is characterized by rms amplitude and correlation length. The calculation results indicate that the rough sapphire surface is easier to extract s-polarized light than p-polarized light, which leads to an increase in the polarization degree. When the rms and correlation length are around 150 nm, the light extraction efficiency (LEE) of LED devices can reach a maximum. Compared to the smooth surface condition, the LEE of Al nanograting LEDs with a period of 300 nm is improved by 65.47% at rms = 150 nm and correlation length = 100 nm. This can be attributed to the critical angle of light extraction increasing from ∼23° on a smooth surface to ∼46° on a rough surface. In addition, due to surface plasmon coupling, when the period of Al nanograting is 100–800 nm, the peak intensity of the TE or TM polarized radiation recombination rate is basically 37%–50% higher than that of the control structure with an Al plane. [ABSTRACT FROM AUTHOR]

The superconducting undulator (SCU) is a trend to be applied for future light sources to obtain the higher light brilliance. A planar SCU prototype with a period of 16 mm, a magnetic gap of 9.5 mm and 50-periods magnet has been under development at the Shanghai Synchrotron Radiation Facility (SSRF) since late 2013. The key technologies including magnet cooling, coil winding, low-temperature alignment of magnet and beam tube, and cryogenic magnetic field measurement have been investigated. A cryocooler-cooled test cryostat was developed for the purpose of both experimentally studying the key technologies and testing the performance of the SCU prototype. Two-stage cryocoolers were applied for cool down, helium liquefaction and keeping the SCU cooled at operation. The SCU magnet and the UHV beam tube were cooled separately. The magnet working at 4.2 K is cooled by thermosiphon-driven liquid helium flowing through the piping in the magnet mandrel. The beam tube, thermal shields and binary leads were conduction-cooled. The beam tube will work at between 4.2 K and 20 K up to dynamic loads generated by the SSRF beam. A set of improved self-centered support assembly for the magnet was developed in order to avoid the complex alignment at low temperature and lower down the machining cost. A cooling approach to effectively cool the junction of the binary lead made of copper and HTS lead commonly used in cryocooler-cooled superconducting systems was adopted and validated. The cryostat was successfully debugged and run at the early of 2016. This paper describes the design details of the cryostat including new approaches to cool the SCU and the binary leads, its fabrication and test results. [ABSTRACT FROM AUTHOR]

The optical polarization characteristics of surface plasmon (SP) coupled AlGaN-based light emitting diodes (LEDs) are investigated theoretically by analyzing the radiation recombination process and scattering process respectively. For the Al0.5Ga0.5N/Al/Al2O3 slab structure, the relative intensity of TE-polarized and TM-polarized spontaneous emission (SE) rate into the SP mode obviously depends on the thickness of the Al layer. The calculation results show that TM dominated emission will be transformed into TE dominated emission with the decrease of the Al thickness, while the emission intensities of both TE/TM polarizations will decrease significantly. In addition, compared with TM polarized emission, TE polarized emission is easier to be extracted by SP coupling. For the Al0.5Ga0.5N/Al nano-particle structure, the ratio of transmittance for TE/TM polarized emission can reach ∼ 3.06, while for the Al free structure, it is only 1.2. Thus, the degree of polarization of SP coupled LED can be improved by the reasonable structural design. [ABSTRACT FROM AUTHOR]

Highlights: [•] Energy performance of business buildings in different climate zones was investigated. [•] Exergy analysis method is used in the process of air cooling and dehumidification. [•] The effect of humidity on energy/exergy is greater than the effect of temperature. [•] Determining indoor temperature and humidity should associate with outdoor climate. [ABSTRACT FROM AUTHOR]

Abstract: In hot summer and cold winter zone in China, air conditioning system has four running modes yearly including cooling with dehumidification, cooling, dehumidification and heating in residential buildings. The conventional air source heat pump (ASHP) system is not designed to independently control temperature and humidity, and is not very suitable for the dehumidification mode in the view of building energy consumption. A novel ASHP system combining radiant cooling/heating for residential buildings was presented. The main feature of this hybrid ASHP system is that desiccant wheel and cooling coil accomplish dehumidification process together, and the regenerative heat needed by the desiccant wheel is supplied by the condenser dissipated heat. Based on simulation studies and performance analysis, this paper predicts the primary energy consumption of the hybrid ASHP system in comparison with the conventional ASHP system during the cooling and heating seasons. It was found that primary energy requirement can be reduced by more than 8% in cooling with dehumidification mode, by 50% in dehumidification mode, and by more than 14% in heating mode. The study results prove that the hybrid ASHP system can keep great energy saving and running cost saving yearly, especially in the dehumidification process. [Copyright &y& Elsevier]

The Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling in a short section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory in the UK. The coupling magnet is a superconducting solenoid mounted around four 201 MHz RF cavities, which produces magnetic field up to 2.6 T on the magnet centerline to keep muons within the iris of RF cavities windows. The coupling coil with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm will be cooled by a pair of 1.5 W at 4.2 K small coolers. This paper will introduce the updated engineering design of the coupling magnet made by ICST in China. The detailed analyses on magnetic fields, stresses induced during the processes of winding, cool down and charging, and cold mass support assembly are presented as well. [ABSTRACT FROM AUTHOR]

Reconfigurability in an antenna system is a desired characteristic that has been the focus of much research in recent years. The paper demonstrates miniature re-configurable antenna designed and fabricated on the high resistivity Si substrate. This antenna can integrate with a novel microelectromechanical systems actuator for reconfiguring the operating frequency and is used for SoC (System on the chip). The switching between the two different frequency bands is achieved through the use of RF-MEMS switches. According to the open/closed experiment results, when switch is on and off, the antenna operating frequency is 12.3 GHz and 13.1 GHz with low return loss, respectively. The final model radiates at two widely separated frequencies with very similar radiation patterns. The proposed concept can be extended to reconfigurable linear antenna arrays or to more complex antenna structures with large improvements in antenna performance. It is important for the next generation wireless communications and integrated antenna system on the chip. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2413–2416, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21979 [ABSTRACT FROM AUTHOR]

In this study, a diisobutyl cyclohexane dicarboxylate (DIBCH) plasticizer was used to modify bitumen for preventing cracking and improving the performance of bitumen pavements. The low-temperature rheological properties of the DIBCH plasticizer–incorporated bitumen were studied via bending beam rheometer (BBR) and dynamic shear rheometer (DSR) tests. Fourier transform infrared spectroscopy (FTIR) and saturate, aromatic, resin, and asphaltene (SARA) fraction tests were performed to investigate the mechanism of the modification of bitumen by the DIBCH plasticizer. The results indicated that the incorporation of DIBCH could enhance the low-temperature deformation ability and stress-relaxation ability of bitumen, and the higher the DIBCH content, the greater the improvement in the low-temperature performance of the bitumen. Furthermore, a microscopic analysis revealed that the modification mechanism of bitumen by the DIBCH plasticizer was that of physical blending, and they did not react chemically. Moreover, the incorporation of DIBCH increased the proportion of light components in the bitumen, thereby improving its low-temperature properties. [ABSTRACT FROM AUTHOR]

The optical properties of deep-ultraviolet (DUV) light-emitting diode (LED) with Al nanograting structure are investigated by three-dimensional (3D) finite-difference time-domain (FDTD) simulation. The peak intensity of TE and TM polarization radiation recombination rate of the grating structure is increased by 33.3% and 22.0% as compared to the control structure with Al plane. The light extraction efficiency (LEE) of the emitted light whose propagation direction is in the plane perpendicular to the Al-grating ridge is much higher than that in the plane parallel to the Al-grating ridge due to the scattering of the grating. Without considering the lateral surface extraction and packaging, the total LEE of the grating structure can be improved by 41.4% as compared to the control structure. The peak intensity of the output spectrum of the DUV LED with the grating structure can be increased by 70.3%.