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1
Content available Research on a square Cassegrain-type solar concentrating reflector with a double pyramid
Zhang Y., Yang H., Jiang P., Mao S., Yu M.
Optica Applicata
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2016
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Vol. 46, nr 3
461--471
EN
A structure of a solar concentrating reflector is designed in this paper to improve the usage of solar energy. For the dark image which is the result of the secondary mirror in the new type of the Cassegrain solar concentrating system, a double pyramid system is used to improve this phenomenon. By eliminating the dark image, the system enhanced the concentration ratio and the working efficiency. Meanwhile, both the primary and secondary mirrors are shaped into a square section in order to get a better match with a square photovoltaic receiver. While the length of the primary mirror is 89m and the block ratio is 20%, the concentration ratio is equal to 118.86.
2
Content available remote Performance of water-soluble composite sulfate sand core for magnesium alloy castings
Jiang P., Liu F., Fan Z., Jiang W., Liu X.
Archives of Civil and Mechanical Engineering
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2016
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Vol. 16, no. 3
494--502
EN
A novel water-soluble sand core hardened by twice microwave heating was fabricated using composite solution of magnesium sulfate and sodium sulfate as a binder. The tensile strength, water absorption rate, gas evolution and water-soluble rate of the water-soluble composite sulfate sand core (WCSSC) were studied. The micro-morphology of WCSSC was observed by scanning electron microscope (SEM). The results show that tensile strength of WCSSC is 1.2 MPa, and the 4 h storage tensile strength exceeds 1 MPa, and also the water-soluble rate is about 42.65 kg/(min m2), which indicates that WCSSC possesses good moisture resistance and water-soluble collapsibility. The microscopic analysis demonstrates that there are some micro-cracks or holes in the bonding bridge that decreases the strength of WCSSC after being put in humidistat for several hours.
3
Content available Theoretical analysis of a hollow laser beam transmitting in an off-axis Cassegrain optical antenna system
Mi C, Jiang P, Yang H., Ke S, Li B, Liu J.
Optica Applicata
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2014
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Vol. 44, nr 3
421--431
EN
The optical model of a Cassegrain optical antenna with a confocal double-parabolic reflector structure has been designed, and the propagation characteristics of a hollow laser beam, which could avoid the loss of energy caused by the subreflector center reflection in the optical antenna, has been researched in this paper. By detailed analysis and numerical calculations of a receiving Cassegrain antenna with different deflection angles, the coupling efficiency curve and 3-D distributions of the receiving light intensity for different inclined angles have been obtained.
4
Content available The forward-wave and backward-wave behaviors of electromagnetic waves in two-dimensional photonic crystals
Jiang P, Yang H., Xie K.
Optica Applicata
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2014
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Vol. 44, nr 1
17--27
EN
The negative refractions are discussed in detail to demonstrate two different two-dimensional photonic crystal structures that undergo negative refractions associated with the backward-wave and forward-wave phenomenon, respectively. The presentation of the left-handed property of effective negative index photonic crystal is followed by a discussion of a backward flowing phase and causality. The forward-wave negative refraction occurs in photonic crystals as a result of anisotropy. This paper is based on the theoretical analysis and is illustrated with the results of finite element method simulations.
5
Content available A new design of a photonic crystal fiber with a beam shaping effect and flexible management of dispersion and confinement loss
Huang Y., Jiang P, Yang H., Yu M.
Optica Applicata
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2014
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Vol. 44, nr 3
375--387
EN
A new design of a guiding-index photonic crystal fiber which possesses a beam shaping effect and flexible control of dispersion has been proposed in this paper. It can shape a Gaussian beam into a circular hollow beam with certain dimension, which can be used in optical communication systems with a Cassegrain antenna to improve transmission efficiency by avoiding the loss of energy caused by the subreflector center reflection. In addition, its dispersion and confinement loss can be changed in a broad range by slightly adjusting structural parameters under condition that the hollow beam dimension remains about the same. Fairly practical properties, zero dispersion or flattened dispersion, can be obtained when structural parameters are set appropriately. A series of models with different parameters are analyzed and compared. Results of numerical simulation show that the ultra-low dispersion of 1.802 ps/km/nm can be obtained when λ = 1.31 μm. Several modest design parameters are given as well.
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