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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]

• A low-pass filter has been designed using periodic self-similar coplanar waveguide. • The filter is used in large integrated or hybrid circuits without require wire bonding. • The paper gives the MEMS surface fabrication processing of the filter. • The MEMS switch has relatively lower driven voltag with 26 V. This paper presents a low-pass filter based on microelectromechanical system using periodic self-similar coplanar waveguide. The device is fabricated on 525-μm high-resistivity silicon substrate using surface micromachining process which partial compatible process with IC. The tunable resonant frequency is achieved using micro-electromechanical contact capacitive switches. The total area of the filter is about 6 mm2 including bias lines and pads. The parameters of the filter has been analyzed by applying the Ansoft-HFSS. When switch is on original state, the measured results of the filter show that the 3-dB cutoff frequency is 16.15 GHz with the average insertion loss of 0.95 dB. The 3 dB cut-off frequency of the reconfigurable filters is 22.85 GHz with the average insertion loss of 2.33 dB. A relatively lower driven voltage is around 26 V. [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]

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]

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 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]

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 kinetic parameters of the thermal decomposition of ETFE were estimated using the conventional methods. • The dynamic DTG data were fitted directly using isothermal n-order and an autocatalytic kinetic model. • Kamal model describes the thermal decomposition kinetics of ETFE in nitrogen perfectly. The thermal decomposition of a commercial poly(ethylene-alt-tetrafluoroethylene) (ETFE) Fluon®C-88AXP, in nitrogen atmosphere has been carried out using thermogravimetric analysis (TG) with dynamic method at different heating rates. The widely used Kissinger equation, Friedman's and Ozawa analysis are used to estimate the activation energy of the degradation reaction. Method of fitting the dynamic derivative thermogram (DTG) data directly using isothermal kinetic model is adopted and the model parameters have been obtained which could not be acquired by using the conventional methods. The TG data of Fluon®C-88AXP could not be described properly using n -order kinetic model but the autocatalytic Kamal model fits the data perfectly. The standard deviations of the calculated mass loss rates from the experimental results decrease from 1.497 × 10−6 to 0.138 × 10−6, with a decrease of 91 %, when Kamal model was used instead of n -order kinetics. This indicates that the thermal decomposition of ETFE in nitrogen atmosphere obeys an autocatalytic kinetics. [ABSTRACT FROM AUTHOR]

GaN-based LEDs with different thickness of n-GaN have been grown on 4-in. Si(1 1 1) substrate by metal–organic chemical vapor deposition. Quality of GaN epilayer has been evaluated by X-ray diffraction (XRD). Strain information in the structure has been directly investigated by means of micro-Raman scattering. It can be concluded that the compressive strain has varied to a tensile one with increasing n-GaN thickness from 0.5 to 2.0 μm. As a result, in a sample with a 2 μm n-GaN thickness, the tensile stress of GaN epilayer was calculated to be 0.44 GPa. Moreover, the strain states of GaN epilayer have been revealed from the variations of its a - and c -lattice constants, which have been calculated using XRD results. In addition, emission peak shift of GaN epilayer has been confirmed by cathodoluminescence measurement, and light output power of LEDs has also been measured. Nevertheless, some correlations in this study would inspire researcher to design much more reasonable GaN-LEDs structures in future. [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]

There are a large number of paramagnetic defects on the surface of as-grown silicon nanowires (SiNWs) in contrast to H-terminated silicon (Si). Herein, SiNWs arrays were fabricated by chemical etching, Nickel nanoparticles (Ni NPs) were deposited on the surface of SiNWs arrays by the electroless plating. The influence of paramagnetic defects on the magnetic property of Ni/SiNWs was investigated and compared to Ni/Si. The paramagnetic defects of as-grown SiNWs and H-terminated Si were studied by ESR and FTIR spectra. The diameter distribution of Ni NPs on the surface of SiNWs arrays and Si was probed by SEM and fitted by the lognormal probability density function. The results reveal that the diameters of Ni NPs are 35.09 ± 0.53 and 34.92 ± 0.72 nm respectively. The magnetic properties of M – H hysteresis loops for Ni/SiNWs and Ni/Si were measured from 5 to 400 K. With the temperature increasing, the saturation magnetization of Ni/SiNWs and Ni/Si decreases gradually due to the thermal activation effect. Overall temperature range (5–400 K), the saturation magnetization of Ni/Si follows the modified Bloch's law. However, the data of Ni/SiNWs are only valid for high temperature range (50–400 K). At low temperature (5 K), there is an abrupt increase and the experimental data deviated from the modified Bloch model. This deviation at low temperature is associated with surface paramagnetic defects of SiNWs. [ABSTRACT FROM AUTHOR]

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]