Terahertz wireless communication through atmospheric atmospheric turbulence and rain

This dissertation focusses on terahertz (THz) wireless communication technology in different weather conditions. The performance of the communication links is mainly studied under propagation through atmospheric turbulence and rain. However, as real outdoor weather conditions are temporally and spatially varying, it is difficult to obtain reproducible atmospheric conditions to verify results of independent measurements making it a challenge to measure and analyze the impact of outdoor atmospheric weather on communication links. Consequently, dedicated indoor weather chambers are designed to produce controllable weather conditions to emulate the real outdoor weather as closely as possible. To emulate turbulent air conditions, an enclosed chamber is developed into which air with controllable airspeeds and temperatures are introduced to generate a variety of atmospheric turbulence for beam propagation. To emulate varying rain conditions, an enclosed chamber is built in which pressurized air forces drops of water through an array of 30 gauge needles. In order to study and compare propagation features of THz links with infrared (IR) links under identical weather conditions, a THz and IR communications lab setup with a maximum data rate of 2.5 Gb/s at 625 GHz carrier frequency and 1.5 μm wavelength, are developed. A usual non return-to-zero (NRZ) format is applied to modulate the IR channel but a duobinary coding technique is used for driving the multiplier chain-based 625 GHz source, which enables signaling at high data rate and higher output power. The power and bit-error rate (BER) on the receiver side are measured, which can be used to analyze the signal performance. To analyze the phase change in the turbulence chamber due to the refractive index change induced by turbulence, a Mach-Zehnder Interferometer with He-Ne laser at 632.8nm is developed. In the same weather conditions, the impact on THz in comparison with IR link is not equivalent due to the spectral dependence on atmospheric turbulence and rain. In the experiment, after THz (625 GHz) and IR (1.5 μm) beams propagate through the same condition, performance of both channels is analyzed and compared. Kolmogrov theory is employed to simulate the atmospheric turbulence which leads to attenuation of THz and IR signals. Mie scattering theory is employed to simulate the attenuation of THz and IR beams due to rain. Under identical turbulence conditions, THz links are superior to IR links. However, the performance of THz and IR links are comparable under identical rain conditions

Students’ Attitudes towards Code-switching in the Bilingual Classroom of Accounting English

This study examines interviews with 58 undergraduates to explore if participants with different language proficiency view code-switching primarily as a) a necessary means because of a lack of words of the target language, or b) a hindrance as a result of interruption in the course of the target language learning. For many decades, bilingual teaching has been dominated by the principle that teachers should use only the target language and avoid using the mother tongue. However, reports show that code-switching is a common phenomenon both in China and abroad. So it is meaningful to study the students’ attitudes toward this phenomenon in order to make this course more effective. Bilingual education is one of the compulsory courses in universities according to the curriculum standard issued by the Ministry of Education in China mainland. It is one of the key points in the Target Evaluation System of School-Running Level for assessing the newly upgraded universities. So accounting English is one of the major courses in the newly upgraded financial university in Hunan province. But bilingual education is not the same as that in the western countries such as those in North America for integrated purposes in the target language society. Students as well as teachers don’t speak the target language in daily lives after class. It is just one of their professional knowledge and competence in case it may be used in future jobs. So, code-switching can not be avoided, and the students’ attitudes toward this should be studied. This report describes several aspects of attitudes from affect, cognition and behaviorist perspectives. It includes attitudes to the code-switching and the bilingual linguistic competence development line. Attitude and linguistic behavior theory was used. This is a working theory which is based on the idea that one linguistic variety is comparable to another, revealing  something of the cognitive component of their attitude. It is characterized by the mentalist approach and behaviorist current. The methods used in our study are known as qualitative and quantitative studies such as interviews, questionnaires and classroom observations. The informants were chosen from the students in three grades in the university majoring in accounting. Detailed information has been processed by the author using SPSS. The studies we have performed showed that bilingual linguistic competence is not acquired in a linear order, it is a curve line. In conclusion, we state that the students’ attitudes vary a lot and the mother tongue is their crutch in their immature stage. Keywords: code switching, bilingual, accounting Englis

Driving Scene Perception Network: Real-time Joint Detection, Depth Estimation and Semantic Segmentation

As the demand for enabling high-level autonomous driving has increased in recent years and visual perception is one of the critical features to enable fully autonomous driving, in this paper, we introduce an efficient approach for simultaneous object detection, depth estimation and pixel-level semantic segmentation using a shared convolutional architecture. The proposed network model, which we named Driving Scene Perception Network (DSPNet), uses multi-level feature maps and multi-task learning to improve the accuracy and efficiency of object detection, depth estimation and image segmentation tasks from a single input image. Hence, the resulting network model uses less than 850 MiB of GPU memory and achieves 14.0 fps on NVIDIA GeForce GTX 1080 with a 1024x512 input image, and both precision and efficiency have been improved over combination of single tasks.Comment: 9 pages, 7 figures, WACV'1

Effects of Educational Productivity on Career Aspiration Among United States High School Students

The purpose of this study was to examine the effects of mathematics-related educational productivity on student career aspiration. We developed a structural model describing the relationship between educational productivity and career aspiration based on Walberg's (1981, 1992) theory of educational productivity. Using data from the Longitudinal Study of American Youth (LSAY), we identified eight mathematics-related factors of educational productivity descriptive of educational outcome, motivation, instructional characteristics, and psychological environment. Statistical results of the structural model supported Walberg's theory of educational productivity from the perspective of student career aspiration (as the educational outcome) in the context of mathematics education. Suggestions were made to enhance student career aspiration and improve the quality of mathematics education.Cette étude avait comme but d'analyser les effets qua la productivité éducationnelle en mathématiques sur les aspirations professionnelles des élèves. En nous appuyant sur la théorie de la productivité éducationnelle de Walberg (1981,1992), nous avons développe un modèle structural qui décrit le rapport entre la productivité éducationnelle et les aspirations professionnelles. Des données de l’étude longitudinale de la jeunesse américaine (Longitudinal Study of American Youth, LSAY) ont permis d'identifier huit facteurs mathématiques de la productivité éducationnelle qui ont des incidences sur la production des élèves, leur motivation, leurs caractéristiques pédagogiques et leur environnement psychologique. Les statistiques qui découlent du modèle structural appuient la théorie de Walberg sur la productivité éducationnelle quant aux aspirations professionnelles des élèves (comme mesure de la production) dans le contexte des cours de mathématiques. Nous proposons des stratégies pour rehausser les aspirations professionnelles des élèves et pour améliorer la qualité de l’enseignement en mathématiques

catena-Poly[[trimethyl­tin(IV)]-μ-(1,1′-binaphthyl-2,2′-diyl phospho­nato)]

In the title polymeric coordination compound, [Sn(CH3)3(C20H12O4P)]n, the Sn atom exhibits a distorted trigonal-bipyramidal coordination geometry with the phosphate O atoms of the 1,1′-binaphthyl-2,2′-diyl phospho­nate ligands in axial positions and equatorial sites occupied by the three methyl groups. Adjacent Sn atoms are bridged by coordination to the two O atoms of each 1,1′-binaphthyl-2,2′-diyl phospho­nate ligand, forming a one-dimensional chain structure parallel to the b axis

Robust Parameter Design of Functional Responses Based on Bayesian SUR Models

As for the robust parameter design of functional responses, a Bayesian Seemingly Unrelated Regression (SUR) model is proposed to take into account the model uncertainty and response variability in this paper. First of all, the SUR model is used to build the functional relationship between the output responses and the input factors at different time points. Also, Bayesian analysis of the SUR model is performed to consider the influence of the model parameter uncertainty on the research results. Secondly, the process means and variances of the functional responses at different time points are estimated by the posterior samples of the simulated responses. Moreover, an integrated performance index (i.e. mean square error) is establish by using the above process means and variances. Then, the optimal parameter settings may be found by minimizing the MSE performance index. Finally, the advantages of the proposed method are illustrated by an example from the literature