One-way Absorption Research Articles

Research on the Optimization of the Physical Education Teaching Mode Based on Cluster Analysis under the Background of Big Data

With the rise of digital campuses, online learning platforms, and the improvement of educational technology, the interaction between teachers and students has entered a new stage. Especially under the influence of CSCL (Computer Supported Collaborative Learning), computer-assisted collaborative learning, and E-learning (Electronic Learning) network digital learning that emerged in recent times, new technologies are changing the way people learn. Students’ learning is not limited to one-way absorption of knowledge taught by teachers, and the interaction between students and teachers, students and students, and the interaction between students and the teaching environment are increasingly appearing in modern teaching classrooms. This paper optimizes the physical education management based on the clustering algorithm under the background of big data, uses the popular Java language to write codes to realize all the functions of the algorithm, and uses some small examples to prove the correctness of the fuzzy clustering algorithm sex. The algorithm reads a file through the input and output streams FileReader and BufferedReader. The content of the file is the relevant information of the physical education mode. It gives the methods to calculate the cluster center (i.e., the center of mass), calculate the distance, correct the fuzzy classification matrix, and display the matrix. (i.e., output matrix), conversion to deterministic classification method, calculation of classification coefficients, and basic functions such as average fuzzy entropy. According to the data, if the FCM clustering method is not used, but the previous average method is used as the evaluation basis, there will be results that we do not want to see, but if we use the FCM algorithm, the evaluation result is that what we want to see is more specific. From the analysis results, thematic teaching + basic teaching seems to be the most popular mode of physical education.

Ultra-wide unidirectional infrared absorber based on 1D gyromagnetic photonic crystals concatenated with general Fibonacci quasi-periodic structure in transverse magnetization

In this paper, an ultra-wide multiband unidirectional absorber based on 1D gyromagnetic magnetized photonic crystals (GMPCs) comprising ferrite material and isotropic dielectrics is investigated under transverse magnetization for transverse electric mode within the infrared regime by the transfer matrix method. Due to the Voigt magneto-optical effect, the magnetically modulated absorber possesses multiple preeminent one-way absorption bands, which run at 12.24–18.80, 25.25–50.05, 51.13–74.90 and 76.67–93.88 THz and in the reverse propagating direction. The absorber displays a splendid reflection phenomenon. These perfect nonreciprocal results can be ascribed to the destruction of the space-time reversal symmetry on account of the anisotropic gyromagnetic ferrite material and quasi-periodic arrangement of the proposed GMPCs. The comparisons of the absorption capacity among the general Fibonacci sequence, the periodic sequence and Thue–Morse sequence are discussed, and the general Fibonacci sequence has its superiority in the expansion of the one-way absorption bandwidth due to its better self-similarity. Besides, the regulative effects of the magnetic field intensity, damping factor and thicknesses of materials on the one-way absorption features are analyzed specifically. This research provides a promising design approach to the tunable infrared optical isolator, waveguide and circulator through the magnetized materials.

Design of a one-way multichannel and wide-angle absorber based on the one-dimensional superconductor photonic crystals with the cascaded quasi-period structure

In this paper, a one-way multichannel and wide-angle absorber based on the one-dimensional superconductor photonic crystals (SPCs) in the terahertz regime is realized via splicing the classical quasi-period sequences and manipulating the ambient temperature properly, whose characteristics and mechanisms are theoretically investigated by the transfer matrix method. The preeminent absorbing features of the proposed SPCs are ascribed to the temperature and frequency-dependent refractive index of the superconductor components, whose imaginary part plays a role in giving rise to the high dissipation. Additionally, when the thickness of the whole structure is of the order of the incident electromagnetic wavelength, the one-way absorption and the reflection in the opposite direction can be perfectly obtained. The calculated results demonstrate that the relative bandwidths of the one-way effective absorption regions in our proposed SPCs can reach to 51.94%, 30.18%, and 19.12%, respectively, and the maximum angle where the wide-angle absorption region can sustain is up to 84° for TM wave by controlling the related parameters. Moreover, the impacts of the external factors such as temperature and incident angle and the interior elements including the thicknesses of diverse layers and the recursive numbers of the cascading sequences on the absorbing performance are also taken into account. To explicitly verify the reliability of our model, the impedance matching and the average refractive index are introduced for explaining the splendid multichannel absorption. As a whole, our research offers effective guidance for the theoretical excogitation of the multichannel and wide-angle absorber in the optical field.

One-way absorption properties in asymmetric single-negative-based Cantor photonic crystals

In this work we theoretically study the one-way optical properties in asymmetric triadic-Cantor-set (TCS) photonic crystals (PCs), air/TCSN/G/TCSM/air, where TCSN is the stage N TCS composed of a lossy epsilon-negative (ENG) material and a lossy mu-negative (MNG) material. In addition, the defect layer G is a dielectric. Our results show that the absorption spectra are different in forward and backward propagation. Specially, it is first discovered that the one-way properties will disappear if the layer thicknesses are large. Besides, the layer thickness limit is smaller when the TCS stage is larger. Additionally, comparing with previous studies, we find that the type of interaction between the defect and non-defect modes is decided by the layer materials of the PC structure.

Non-symmetric flexural wave scattering and one-way extreme absorption.

The possibility of asymmetric absorption and reflection for flexural waves is demonstrated through analytical and numerical examples. The emphasis is on the one-dimensional (1D) case of flexural motion of a beam for which combinations of point scatterers are considered, which together provide asymmetric scattering. The scatterers are attached damped oscillators characterized by effective impedances, analogous to effective configurations in 1D acoustic waveguides. By selecting the impedances of a pair of closely spaced scatterers it is shown that it is possible to obtain almost total absorption for incidence on one side, with almost total reflection if incident from the other side. The one-way absorption is illustrated through numerous examples of impedance pairs that satisfy the necessary conditions for zero reflectivity for incidence from one direction. Examples of almost total and zero reflection for different incidences are examined in detail, showing the distinct wave dynamics of flexural waves as compared with acoustics.

Gender geography in Japan: the trajectory, fruits of research and future challenges

The indication by female geographers outside of Japan that, due to the original dearth of female geographers, a gender perspective had been missing from geography held true for Japan as well. In 1993, Yoshida was the first person to discuss the importance of a gender perspective in a Japanese journal of geography. Nearly 25 years have passed since its publication, and the aim of this paper is to investigate what developments have taken place in Japanese geography on gender research. As the accomplishments of feminist geography in English-speaking countries was merely ‘imported’ to Japan around 1990, there is no firm starting point of ‘feminist’ geography, which originated in women’s liberation movement of the 1970s, in the country. Rather, it can be said that Japanese geographers, regardless of sex, undertake gender geography, which does not limit a particular sex as the sole subject and/or object of research. The results of research on gender geography by men geographers began to appear from the year 2000. The use of life history method emerged as a trend in research since 2000. While there has been gradual progress in research on gender geography in Japan, the number of researchers are still by no means large. While Japanese geography has hitherto involved a one-way absorption of the fruits of overseas research on gender/feminist geographies, at least based on studies that have already accumulated in Japan, it is now necessary that Japanese study results also be communicated to overseas.

Investigation of one-way absorption properties in an asymmetric photonic crystal containing a semiconductor defect.

We theoretically study the one-way absorption in two 1D defective asymmetric photonic crystals, air/(DB)NA(BD)M/air and air/(DB)NA(BD)MA(DB)NA(BD)M/air, where A and B are dielectrics, D is the semiconductor, n-InSb, and N, M are stack numbers with N≠M. It is revealed that their absorption spectra exhibit one-way properties. We also find that the number of one-way absorption peaks depends on the symmetry and number of defect layers, which are similar to the defect modes in the transmittance spectra of the usual symmetry photonic crystals. Additionally, effects of the incident angles for both TE and TM waves on the one-way feature are also presented. At a large incident angle, the TE wave is almost reflected, whereas the TM wave can have a partial absorption.

Enhanced and one-way absorptance of LiNiO2 thin films in one-dimensional photonic crystals

The refractive index of LiNiO2 thin films is complex and exhibits both dielectric and metallic properties. With LiNiO2 thin films coated on or inserted in photonic crystals (PCs), it is possible to enhance the absorptance in the designed (AB)nLiNiO2(BA)m PC structures. One-way absorption in the photonic bandgap of (AB) PCs has been observed via changing the optical transmitting direction. The positions, width, and strength of the absorption peaks depend on the thickness of the LiNiO2 films, the incident angles, and the transverse electric/transverse magnetic modes. The photonic band structure can be employed to determine the allowed and forbidden photonic modes and the related optical properties for (AB) PC and (AB)nLiNiO2 PCs. These novel absorption characteristics can enrich the optoelectric properties of LiNiO2 thin films.

Experimental investigation of multiple near-perfect absorptions in sandwich structures containing thin metallic films.

We experimentally investigated near-perfect optical absorption in sandwich structures comprising a thin metallic film whose thickness is larger than the skin depth, a top dielectric layer and a truncated photonic crystal. Single and multiple near-perfect absorptions were realized by tuning the thickness of the top layer. Based on the electromagnetic field intensity distributions at the absorption wavelengths, single near-perfect absorption originated from the tunneling effect of the optical Tamm state, while multiple near-complete absorptions mainly originated from Fabry-Perot resonances. Additionally, the structures showed good one-way absorption properties. The experimental results agreed well with theoretical values. These structures may be important for the fabrication of single or multichannel perfect absorbers.

Development and Validation of an in vitro Experimental GastroIntestinal Dialysis Model with Colon Phase to Study the Availability and Colonic Metabolisation of Polyphenolic Compounds.

The biological effects of polyphenols depend on their mechanism of action in the body. This is affected by bioconversion by colon microbiota and absorption of colonic metabolites. We developed and validated an in vitro continuous flow dialysis model with colon phase (GastroIntestinal dialysis model with colon phase) to study the gastrointestinal metabolism and absorption of phenolic food constituents. Chlorogenic acid was used as model compound. The physiological conditions during gastrointestinal digestion were mimicked. A continuous flow dialysis system simulated the one-way absorption by passive diffusion from lumen to mucosa. The colon phase was developed using pooled faecal suspensions. Several methodological aspects including implementation of an anaerobic environment, adapted Wilkins Chalgren broth medium, 1.10(8) CFU/mL bacteria suspension as inoculum, pH adaptation to 5.8 and implementation of the dialysis system were conducted. Validation of the GastroIntestinal dialysis model with colon phase system showed a good recovery and precision (CV < 16 %). Availability of chlorogenic acid in the small intestinal phase (37 ± 3 %) of the GastroIntestinal dialysis model with colon phase is comparable with in vivo studies on ileostomy patients. In the colon phase, the human faecal microbiota deconjugated chlorogenic acid to caffeic acid, 3,4-dihydroxyphenyl propionic acid, 4-hydroxybenzoic acid, 3- or 4-hydroxyphenyl acetic acid, 2-methoxy-4-methylphenol and 3-phenylpropionic acid. The GastroIntestinal dialysis model with colon phase is a new, reliable gastrointestinal simulation system. It permits a fast and easy way to predict the availability of complex secondary metabolites, and to detect metabolites in an early stage after digestion. Isolation and identification of these metabolites may be used as references for in vivo bioavailability experiments and for investigating their bioactivity in in vitro experiments.

One-way absorption of terahertz waves in rod-type and multilayer structures containing polar dielectrics

One-way absorption can be obtained at terahertz frequencies in low-profile rod-type and multilayer dielectric structures with broken spatial inversion symmetry, which contain either a rod layer or an ultrathin homogeneous layer made of a polar dielectric. Perfect absorption for one of the two opposite incidence directions and perfect reflection for the other one are observed at the edge of the polaritonic gap in a wide range of the incident angle variation, when the thickness of the entire structure is of the order of the incident wavelength. Moreover, this regime appears in a wide frequency range, in which the forward-to-backward absorption contrast is strong. The exploited mechanism is connected with the parameter adjustment that enables the location of the polaritonic gap of the polar dielectric, of which the lossy part of the structure is made, inside the stop band arising due to the periodicity of the lossless part of the structure that is made of a nondispersive dielectric. It also exploits absorption enhancement in the lossy part by backing it with the highly reflecting lossless part, which has alternating stop and pass bands.

One-way absorption behaviour in defective 1D dielectric-metal photonic crystal

In this paper, the one-way absorption property in one-dimensional dielectric/metal photonic crystal structure with a dielectric defect layer is studied. The effects of incident angle and state of polarization on one-way absorption behaviour of the anti-resonant (AR) mode are investigated. The normally incident wave from left to right propagation is totally allowed to penetrate to the structure but right to left propagation totally reflected at the same wavelength. It is found that, with increasing of the incident angle, the AR mode shifts to the lower wavelengths and its intensity decreases. Simultaneously, another AR mode with reversed one-way property appears at higher wavelength. The one-way behaviour on absorption is observed at the both states of polarizations but is localized on different wavelengths. Those effects, are suggesting that the proposed structure can be used as a direction sense polarization splitter or reflector/antireflector device.

Conflicts and Adjustments of Foreign Wives Married to Korean Men: Filipina Wives in Rural Korea

The number of the international marriage has been rapidly growing in Korea since 1990s. According to the Korea National Statistics Office, 11.4% of the total number of marriages reported in 2004 are those contracted between Koreans and foreign nationalities. It means that more than one out of 10 marriages in Korea turns out to be international marriage. What is noteworthy is that the number of marriages between Korean men and women of other nationalities more than double that between Korean women and foreign men.<BR> This study examines the conflicts and adjustments of foreign wives in rural Korea. It focuses on the experience of Filipina wives. For this study, I have conducted formal and informal interviews as well as participant observation between september 2003 and september 2004. I have met with more than 50 Filipina wives in South Cholla Province and conducted in-depth interviews with 20 of them.<BR> Previous studies and various reports on the foreign wives in Korea view them as the passive victims of the macro socioeconomic forces such as globalization, unequal economic development between countries, feminization of poverty, gendered international labor market and the patriarchal local family system. The “victim perspective” portrays the female marriage migrants from the poor country as passive pawns trapped between the dire poverty of their home country and the oppressive demand of the Korean patriarchal family system. Female marriage migrants tend to be represented as the unified and generalized category of people.<BR> In this study I deal with them as multiple social actors from various socio-cultural backgrounds with diverse motives opting for the international marriage. I think that they can see the possibilities open to them as well as dangers entailed in them. In adjusting to and positioning themselves in Korean society they make use of various socio-cultural resources and networks<BR> Their adjustment strategies and future life plans suggest that the international marriage between foreign women and Korean men should not be understood as the one-way absorption of foreign wives into the Korean society. Foreign wives carry the strong potential as the agents of socio-cultural changes in rural Korean society. Their family reproduction involves the transnational networks and strategies.

Electromagnetic-wave absorption in highly collisional plasmas

An experimental and theoretical investigation of basic plasma-physics processes relating to the absorption of electromagnetic waves in collisional plasmas is described. One-way absorption of 63 dB at 4 GHz was demonstrated in a section of plasma-loaded rectangular C-band waveguide. The ultraviolet photoionization plasma-production technique employed permits independent variation of the plasma-density profile and electron-collision frequency. A theoretical model for the absorption and scattering processes, which includes scattering contributions from the plasma-vacuum interface, and partial reflections and collisional absorption in the bulk plasma, is in reasonable agreement with the experimental results.