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In the detection of acoustic emission signals due to compressed air leakage, various complicated factors make it difficult to position leakage sources. Specially, although leakage ultrasonic signals are wanted in the detection, the reflected ones belong to interfering factors. In this research, with an air leak scanner, predefined experiments were implemented to find different characters between reflected...
Thomson scattering is a phenomenon taking place for low energy X and gamma ray photons. It is known as the basis of photon reflection from surfaces at grazing angle of incidence. Using existing data on terahertz reflection coefficient, it is shown that Thompson scattering is a plausible explanation for terahertz reflection from surfaces. In the present work, preliminary computation shows that the...
I am creating a new programming language and editor that is aimed towards authoring interactive behaviors. This language is intended to allow more interaction designers to write their own interactive applications. This paper discusses the motivation, method, and design ideas for such a language.
In this paper, we studied and designed a wideband four-arm sinuous antenna for 4-14GHz. To get unidirectional performance, we added a backed reflective cavity at one side of the antenna. It was found that better unidirectional performance was obtained with cavity-backed filled with absorbing material. Also the absorbing properties of the absorbing material were discussed in this paper. In the end,...
In this paper, the confinement loss diagram (CLD) is combined with the modal filtering approach to design low loss single-mode terahertz (THz) Bragg fibers. To filter out the TM01 mode, the confinement loss diagram is exploited to locate a cutoff point which allows the use of a larger air core. Consequently, a lower loss can be obtained while only the HE11 can propagate effectively. The designed Bragg...
We model and compare the uncertainties of the refractive index and the coefficient of absorption of materials in the far-infrared, determined from THz time-domain spectroscopy performed in reflection and in transmission. Our study is experimentally validated. We give rules to select the most appropriate experimental technique regarding studied samples.
A monochromatic millimeter wave system coupled with an infrared temperature sensor has been used to investigate pictorial artworks. The flexibility of the system makes it possible to rapidly reveal buried layer information such as a graphite handmade sketch covered by paintings.
Three well-known methods of layered structure permittivity profile reconstruction on the basis of microwave probing are under consideration. The methods are discrete analog of Gel'fand-Levitan integral equation method supposing Goupillaud model, the method of dynamic deconvolution and the method based on Newton-Kantorovich iterative scheme implementation to Riccati differential equation. The methods...
In designing of anechoic chamber with higher quality, when requirements of quiet zone index are higher, it must use the geometrical theory of diffraction instead of the geometrical optics for accuracy. The utilities of the theory in design have been discussed in this paper. Besides, in analysis of reflectivity versus incident angle of absorbing materials, it's used to use linear interpolating method...
We report about an algorithmic approach to identify substances inside a sample using their complete characteristic absorption spectra from a tomographic measurement with ultrashort THz-pulses. Furthermore we show an algorithmic approach for tomographic reflection measurements.
Critical wavelength concept is proposed in the paper in order to describe the different behaviors of eddy currents and different harmonic losses in solid poles or non-insulated laminated poles of electrical machines. The concept is developed from an eddy current model which is commonly used for the calculation of slotting effects in solid rotors. Two synchronous machines are used for illustrating...
The UWB reflected signal at 4.7 GHz is characterized and measured for the application of short-circuited reflection material analysis with aluminum backing the sample. The sub-pulse with 120-ps pulse width is used to characterize the UWB reflected wave propagation phenomenon in some aluminum plates with different thickness. It was found the normalized amplitude of principal sub-pulse that is generated...
Satellite remote sensing has been an important method of marine monitoring. In this paper, according to the requirements of marine monitoring and marine management, the authors produced figures to show the coastline changes, distributions of suspended sediment and chlorophyll-a based on the data from Landsat-5 and synchronous monitoring data of Yellow River's mouth and Laizhou Bay in different periods...
In this paper it is demonstrated that these assumptions may not be applicable to the absorbing materials commonly used at VHF/UHF frequency bands. If the chamber operates down to VHF/UHF frequencies, then the height of foam impregnated absorber components may vary from 0.9m up to 2.4m or more. The reflectivity of these absorbing materials is critical at VHF/UHF, as the chamber cross-section may span...
Terahertz (THz) waves can penetrate opaque materials and fingerprint spectra appear as those in infrared bands. The technique is expected to be used as a new non-invasive analysis method for various materials. Time domain reflection imaging, in particular, uses THz pulses that propagate in specimens, and in this technique, pulses reflected from the internal boundaries of the specimen indicate the...
The overlay method is used successfully to measure the properties of conductorbacked materials using waveguide probes. However, it is shown here that the method cannot be used with free-space systems that assume plane wave excitation. Since every combination of overlay materials provides exactly the same information about the underlying unknown material, there is insufficient information for obtaining...
This paper summarizes the research and development of multispectral infrared mirror designs based on the surface patterning of coating materials. Three-dimensional structures can be etched into the coating materials to create infrared devices capable of meeting a wide variety of different multispectral performance requirements. The design methodology developed in this work is based on optimizing the...
Reflection plays an important role in improving learning performance. Hence, this study attempts to explore whether learners' reflection levels can be improved when reflection teaching strategies fit with learners' thinking styles in a web-based learning environment. Three reflection teaching strategies, namely constructive, guiding, and inductive, were designed to match with three thinking styles,...
While today's learning management systems (LMSs) provide lot of support for teachers to assist them in holding online courses, they typically do not consider students' individual differences in the composition and structure of courses. In this paper, we introduce a mechanism for extending LMSs' functionality to provide learners with courses that fit their individual learning styles, using adaptive...
The dielectric parameters measurement is very important for not only practical applications such as geophysical prospecting, remote sensing, and material study, but also in theory. We choose open-ended coaxial method. The electromagnetic modeling is used to calculate the reflection coefficient. We collected 64 samples in this nickel-cupper mine and the samples are measured and the data is processed...
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