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Air-cooled frost-free household refrigerators have become popular in the market because of their large storage volume and frost-free compartments. However, the large amount of power consumed by the defrosting process of the evaporator restricts the widespread application of such refrigerators. In this study, a new type of defrosting system using outdoor air (DSUOA) is developed. The operation modes (refrigeration and defrosting cycles) of the overall system are proposed. An experimental prototype is built, and an experimental study is conducted for different temperature ranges (12–22 °C, 22–45 °C, and 0–12 °C). Results show that the power consumption of DSUOA is 77.6–98.2% less than that of the electric heater defrosting system under a similar defrosting time.

A series of 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (PAPTS) grafted on Materials of Institute Lavoisier-101(Cr) [MIL-101(Cr)] porous adsorbent with varied PAPTS loadings were synthesized and characterized by powder X-ray diffraction patterns (PXRD), N2 adsorption-desorption measurement at 77 K, Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). The water vapor adsorption isotherms were obtained by gravimetric method. Water adsorption isotherms and dynamic on MIL-101 as well as PAPTS- MIL-101(Cr) are discussed simultaneously. Results indicated that even though the Brunauer-Emmett-Teller (BET) surface areas of PAPTS-MIL-101(Cr)-0.5 and PAPTS-MIL-101(Cr)-0.75 were reduced by approximately 50% compared with that of the original MIL-101(Cr), which have slightly higher water uptake capacities in a region of 0.30

This paper analyzes the air quality monitoring data of Qingyang, Tianshui and Pingliang in northwestern China in 2015 by time series analysis. The research results are as follows: (1) the concentrations of PM2.5, PM10 and SO2 in the three cities began to decline in March, reached a minimum in September before rising gradually; (2) concentrations of PM2.5, PM10 and SO2 in the three cities were low in summer and autumn, but high in winter and spring; (3) the coefficient of correlation among PM2.5, PM10 and SO2 in the three cities was greater than 0.589, indicating a strong correlation.

In this article, MIL-101(Cr) powder material was successfully prepared by hydrothermal synthesis and combined with different mass fractions of CaCl2 by immersion method to obtain MIL-101(Cr)/CaCl2 composite materials. The physical properties of the adsorbent were determined by X-ray powder diffraction, N2 adsorption/desorption isotherm, TGA and FTIR. The water vapor adsorption performance of MOFs was tested by a gravimetric instrument to analyze the underlying mechanism. Results indicated that the specific surface area, total pore volume, and pore size distribution of micropores and mesopores of MIL-101(Cr)/CaCl2 composites decreased with increasing CaCl2 content. When P/P0 = 0.9, the water vapor equilibrium adsorption capacities of MIL-101(Cr), MIL-101(Cr)/CaCl2-10%, MIL-101(Cr)/CaCl2-20%, and MIL-101(Cr)/CaCl2-30% were 1.05, 0.88, 1.13, and 1.35 g/g, respectively. MIL-101(Cr)/CaCl2-30% agglomerated after water absorption, so MIL-101(Cr)/CaCl2-20% was selected as the final experimental material. The water vapor adsorption heat of MIL-101(Cr)/CaCl2-20% was 42–58 kJ/mol, which is close to the evaporation enthalpy of water (44 kJ/mol at 25 °C). The analysis of the adsorption kinetics showed the relatively uniform adsorption rate of MIL-101(Cr)/CaCl2-20%. Overall, MIL-101(Cr)/CaCl2-20% exhibited superior water vapor adsorption performance and have great potential for application to adsorption heat pumps.

Two kinds of binary optical elements used in multi-channel one-dimensional Fourier spectrum analysis are introduced. One is equivalent to two overlapped line-type zone plates that are in two different orientations, and the other is composed of a line-type zone plate and a circular zone plate. In the output plane, the designed elements can simultaneously perform one-dimensional imaging of the input object in one direction and one-dimensional Fourier transformation in the perpendicular direction, respectively. Consequently, a series of one-dimensional spectra along different sectional lines of the object can be produced in the output plane. The elements are fabricated using the binary optical technique. Experiments show that these binary optical elements work well and are suitable for lensless optical processing systems.

We have proposed a novel principle for design of the binary Gabor zone plate (GZP) that can produce the desired focal-plane curves. The modified GZP can be fabricated as easily as the Fresnel zone plate (FZP). The proposed GZP has great flexibility in terms of manipulating the focusing properties. Optical experiments have confirmed the reliability of the GZP in focusing light into the specified area. The investigation on the factors affecting the performance of the GZP is presented. The low cost and easy production of the element show that it can serve an alternative to refractive lens in the short wavelength region where refractive optics is not applicable owing to possible strong absorption.

A self-focusing matched filter is proposed in this paper. The filter function is constructed by adding a quadratic phase factor to the conjugate Fourier spectrum of an object to be recognized. The filter is recorded by using computer-generated holographic techniques. Because of the property of self-focusing, the optical path of the recognition system becomes much simpler and is convenient to adjust. The experiments on the pattern recognition are performed. It is shown that this filter is suitable for recognizing the objects with different scales.

In this paper we introduce a new phase type combined optical element. The element is combined with Dammann grating and Fresnel zone plate in the same substrate by microelectronics technique, hence it has splitting functions of the Dammann grating and self-focusing function of the Fresnel plate. It can produce uniform multiple images by itself. We experimentally designed and fabricated an 9x9 multiple image element, and results show that the element can realize the multiple images we require and the intensity of each image is the same. Relative error is less than 5%.

Usually in reconstruction of Fourier computer-generated hologram[FCGH] the lens is necessary to make imaging at finite distance instead of imaging at infinite originally. The reconstructed images are mutual inverted ( one upright image,another inverted image) both appear in a same plane. Whether the imaging lens in reconstruction FCGH will be able to omit? Whether two reconstructed images will be able to separate in spatial? Whether two images have an identical direction and different shape in the same plane? It is the motivation for us to do this study. Through theoretic analysis and experimental reconstruction these assume can be realized essentially.

A new type of diffractive optical bar code produced by computer-generated holographic technology is proposed. The message in the proposed bar code is hidden in the diffracted light of the bar code element and can be read from the first diffraction order. In contrast to the conventional hidden bar code, which needs a lens to focus the diffracted light, the proposed hidden bar code has a property of self-focusing. This self-focusing ability is achieved by modulating a function of the Fresnel zone plate into the bar code format. Consequently, the read-out process for the information in this hidden bar code avoids the use of a lens. Experiments have shown the feasibility of the proposed bar code and confirmed that it can perform better than the conventional hidden bar code.

A new type of computer-generated hologram (CGH) is described in this research. Upon the base of a two-channel CGH, it can generate four independent images in four different directions with the addition of positive or negative quadratic phase factors on the object spectrum; it has the character of self-focus. Results of the experiment are provided.