More metal fiber content of blended electromagnetic shielding (EMS) fabric results in higher shielding effectiveness (SE) of the fabric. However, there is little information about the influence of the metal fiber content on the SE considering the fabric structure. This study constructs an index of metal fiber content per unit area (MFCPUA), and discusses the influence of the metal fiber content on the SE of the EMS fabric when fabric parameters are changed. Computations for the MFCPUA and the thickness and porosity of the metal fiber arrangement are given, and then experiments are designed to test the SE of different EMS fabric samples. According to the experimental results, the influence of the MFCPUA on the SE is analyzed and influence mechanism is discussed when the fabric weaves, emission frequencies and weft and warp densities are changed. The results show that the MFCPUA and the SE are in positive increase relation; the frequency and the SE are in the negative increase relation when the metal fiber content is unchanged. The influence of the fabric weave type on the SE depends on the length of the yarn floats; the SE values of fabric with the same weave are the same when the MFCPUA is the same regardless of the fabric density.
We report a brand new recycling route of waste marble powder, by means of surface modification with homemade nano-TiO 2 particles to produce low cost coating materials for the application in air quality improvement. The as-prepared nano-TiO 2 in anatase phase exhibits excellent photocatalytic characteristic, reflected by the high degradation rate of over 95% of methylene blue within 6 hours of UV irradiation. The prepared coating consisting of nano-TiO 2 clad marble powder was tested by monitoring the decomposition rate of formaldehyde gas. A high degradation efficiency of about 95% within 9 hours of illumination is achieved, demonstrating a promising potential for removing the harmful and toxic organic pollutants in air while applying this coating in buildings both interiorly and exteriorly.
Purpose
– The purpose of this paper is to explore the influence of hole on shielding effectiveness (SE) of electromagnetic shielding (EMS) fabric under incident polarization wave, and to propose a “Key Size” theory to explain the influence mechanism.
Design/methodology/approach
– “Key Size” parameters describing hole shape are established, and a number of representative samples with rectangular and oval holes are made. SE of the samples are tested by waveguide testing system. Influence of the hole on the SE of the samples is analyzed according to vertical or horizontal maximum size and polarization wave direction. Finally, the “Key Size theory” and “Secondary Size theory” are proposed to explain the influencing mechanism.
Findings
– The hole influences on the SE are related to the vertical and the horizontal maximum size of the holes and the direction of the polarization wave. As the direction of the polarization wave is vertical (or horizontal), greater maximum size results in lower SE. As the maximum size is constant, greater maximum size causes lower SE. As the maximum size reaches to a certain value, a dividing point of the SE occurs. As the direction of the polarization wave is consistent with the direction of the maximum size, same hole area results in same SE.
Originality/value
– The explored influences and mechanism provide an important guiding reference for the hole design of the EMS fabric, and can be applied to the holes design of the EMS garment, composite materials, and tents.
The spontaneous emission of a two-level atom, located in an isotropic photonic crystal with dynamically modulated photonic band edge, has been studied. When the photonic band edge is modulated with step functions or triangle functions, the evolution of atomic population on the upper level has been discussed. When the photonic band edge is modulated with step functions, the dynamics of atomic population depends not only on the detuning value of the atomic transition frequency from the band edge, but also on the time point of stepping. With the different time point of stepping, the dynamics of atomic population after stepping is different. When the photonic band edge is modulated with triangle functions, the atomic population oscillates quasi-periodically while decaying in general. The oscillation frequency, peak and valley values, and the decaying rate of oscillation can be modulated by choosing the frequency and initial phase of triangle functions.
A triple-cathode plasma surface alloying technology has been invented, which has been used to carburize on a surface of pure titanium in an operation of hydrogen-free. A plasma carburized layer has been obtained on a sample of pure titanium, which features were examined with GDA and ToF_SIMS. The result is pointed that this kind of carburized layer possesses some special and interesting characteristics.
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