The use of spectral information in the development of novel techniques for speech-based cognitive load classification

The cognitive load of a user refers to the amount of mental demand imposed on the user when performing a particular task. Estimating the cognitive load (CL) level of the users is necessary to adjust the workload imposed on them accordingly in order to improve task performance. The current speech based CL classification systems are not adequate for commercial use due to their low performance particularly in noisy environments. This thesis proposes many techniques to improve the performance of the speech based cognitive load classification system in both clean and noisy conditions. This thesis analyses and presents the effectiveness of speech features such as spectral centroid frequency (SCF) and spectral centroid amplitude (SCA) for CL classification. Sub-systems based on SCF and SCA features were developed and fused with the traditional Mel frequency cepstral coefficients (MFCC) based system, producing an 8.9% and 31.5% relative error rate reduction respectively when compared to the MFCC-based system alone. The Stroop test corpus was used in these experiments. The investigation into cognitive load information in the form of spectral distribution in different subbands shows that the information distributed in the low frequency subband is significantly higher than the high frequency subband. Two different methods are proposed to utilize this finding. The first method, called the multi-band approach, uses a weighting scheme to emphasize the speech features in low frequency subbands. The cognitive load classification accuracy of this approach is shown to be higher than a system based on a non-weighting scheme. The second method is to design an effective filterbank based on the spectral distribution of cognitive load information using the Kullback-Leibler distance measure. It is shown that the designed filterbank consistently provides higher classification accuracies than other existing filterbanks such as mel, Bark, and equivalent rectangular bandwidth. A discrete cosine transform based speech enhancement technique is proposed in order to increase the robustness of the CL classification system and found to be more suitable than other methods investigated. This proposed method provides a 3.0% average relative error rate reduction for the seven types of noise and five levels of SNR used. In particular, it provides a maximum of 7.5% relative error rate reduction for the F16 noise (in NOISEX-92 database) at 20 dB SNR

Capital diversion in Vietnamese state-owned enterprises

Purpose – The authors estimated the hidden overhead (capital diversion or wasteful use of capital) of Vietnam state-owned enterprises (SOEs). Design/methodology/approach – The authors used a panel data set of 10,200 Vietnam SOEs observed over the period 2010–2018. The authors modeled and estimated the hidden overhead by using a stochastic production frontier. The hidden overhead parameter is modelled as the technical inefficiency in the production function. Findings – Vietnam SOEs are very capital intensive. The hidden overhead (or the wasteful use of capital) is very high with an average rate of 69%. Research limitations/implications – Alternative estimation methods should be used to account for endogeneity in production inputs. Lack of comparison with the Vietnam private firms. Originality/value – The paper proposes an original way to quantify hidden overhead (or capital diversion) in the Vietnam SOEs. The finding (a capital diversion rate of 69% on average) is astonishing. It calls for an urgent and profound reform of the Vietnam SOEs

Influence of Time Dependence of Dynamic Laser Parameter on the Three Modes Random Laser Operation

In this report we demonstrate the transformation of the photon density curves in operation of a three modes random laser when the gain coefficients of modes depending on time.Supposing gain coefficients having Gaussian profile and using Matlab language, we have solved the basic equations describing the operation of a three modes random laser. The received results give us more real knowledge about the appearance of modes in random laser

Exploiting secure performance of full-duplex decode and forward in optimal relay selection networks

In the presence of an illegitimate user, we investigate the secrecy outage probability (SOP) of the optimal relay selection (ORS) networks by applying decode-and-forward (DnF) based full-duplex (FD) relaying mode. The closed-form expressions for the allocations of the end-to-end signal-to-interference-plus-noise ratio (SINR) in each wireless network are derived as well as the closed-form expression for the exact SOP of the proposed ORS system is presented under Rayleigh fading schemes. As an important achievement, SOP is also compared between orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) schemes. Our results reveal that the SOP of the suggested scheme can be considerably influenced by several parameters involved, including the number of relays, the average signal-to-noise ratio (SNR) of eavesdropper links, transmit power and the average residual self-interference (SI) enforced on the FD relays.Web of Science244767

ANALYSIS OF THE POPULARITY OF VOCABULARY USED WHEN PERFORMING SPEAKING ACTIVITIES IN THE CLASS OF FIRST-YEAR ENGLISH LANGUAGE STUDENTS IN THE DIRECTION OF DISCOURSE ANALYSIS

Vocabulary learning is extremely important when learning a foreign language. Fluency in a language depends on vocabulary and its use in specific situations. Speaking well is using vocabulary flexibly and speaking fluently. Researching the popularity of vocabulary is analyzing the prevalence of vocabulary used by linguistics students in communication from discourse analysis. This is a topic the research team is working on. This project will help the researchers learn about common vocabulary that students often use to communicate outside or in the classroom. Thereby understanding whether the vocabulary that students use is diverse, rich, and for the right purpose or not. This study will help students have a more comprehensive view of the ways to use words in communication. In addition, it also helps students improve their communication vocabulary, helps in exams and can be useful for later work. In this study, the research team will investigate the students' ability to use spoken vocabulary, i.e., frequency and extent of vocabulary usage.  Article visualizations

A SURVEY OF STUDENTS’ ABILITY OF IDENTIFYING ERRORS IN WRONG SOLUTIONS FOR THE MATHEMATICAL PROBLEMS RELATED TO THE MONOTONICITY OF FUNCTIONS

The monotonicity of a function plays an important role in the general mathematics curriculum in Vietnam, because it is considered as an effective tool for solving mathematical problems involved with the monotonic intervals of functions, their extreme, absolute maximum value and absolute minimum value. Normally, students commit errors in solving these problems because of their complexity and difficulty. In addition, specific characteristics of knowledge also make children make mistakes. The sample consisted of 362 students, and they had the task of identifying errors in false assumptions. From the results of the survey, it was found that when dealing with the monotonicity of the functions, students were still misled.  Article visualizations

UAV based satellite-terrestrial systems with hardware impairment and imperfect SIC: Performance analysis of user pairs

We investigated the outage performance of non-orthogonal multiple access (NOMA) in satellite-terrestrial systems which contain hardware impairments. An unmanned aerial vehicle (UAV) was implemented to forward signals from a satellite to users on the ground. A two-user model was applied to achieve spectral efficiency. In practical, real-life scenarios, the UAV and ground users encounter issues with imperfect hardware. We examined the performance gap between two users experiencing practical problems such as hardware impairment and imperfect successive interference cancellation (SIC). To implement a practical scenario, Shadow-Rician fading was adopted in the satellite links, and Rician fading was employed in the terrestrial links for ground users. In the main results, we derived the closed-form expression of the outage probability, and to evaluate the system performance of two NOMA users, we obtained the approximate expressions for high signal-to-noise ratios (SNR). Finally, we produced Monte-Carlo simulations to verify the analytical expressions and demonstrate the effect of the main system parameters, such as the number of transmit antennas on the satellite, transmit SNR, and level of hardware impairment on the system performance metric.Web of Science911793711792

SYNTHESIS OF SILVER NANOPARTICLES DOPED IN THE ZEOLITE FRAMEWORK BY CHEMICAL REDUCTION METHOD

ABSTRACT Silver ions (Ag+) were introduced at first into the porous zeolite 4A lattice by an ion-exchange route. And then silver nanoparticles (AgNPs) were synthesized in the zeolite framework by chemical reduction method using hydrazine hydrate (N2H4. H2O) as reducing agent. The synthesized AgNPs/zeolite product was characterized by ultraviolet-visible spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed the maximum absorption wavelength (lmax) of AgNPs/zeolite at 427 nm and the average size of the metallic AgNPs doped in the zeolite of about 30 nm. The synthesis process has been considered as suitable one to prepare AgNPs/zeolite with AgNPs content in zeolite of about 1.2% on large scale. The obtained AgNPs/zeolite product has been used for production of porous ceramic water filters with efficiently bacterial disinfection effect for treatment of drinking water

Geo-chemical fractionations of arsenic and lead in the surface sediments of Thuy Trieu lagoon, Khanh Hoa province

The sequential extraction method of Tessier et al. was applied to identify the phase associations of As and Pb in the surface sediment of Thuy Trieu lagoon. The results showed that these two metals were mainly found in the residual fractions. Meanwhile, the carbonate fractions stayed at the lowest portions. Levels of arsenic and lead as Fe-Mn oxide fractions were higher than those as organic fractions and exchangeable fractions. Exchangeable fractions and carbonate fractions of two elements seemed to increase in rainy season. Generally, the mobility of Pb was higher than that of As. In the sediments of Thuy Trieu lagoon, Pb levels cannot currently cause adverse effects on the ecosystems. On the contrary, the risk of As was assessed as moderate level