Frequency Estimation Using Time-Frequency Based Methods

Any periodic signal can be decomposed into a sum of oscillating functions. Traditionally, cosine and sine segments have been used to represent a single period of the periodic signal (Fourier Series). In more general cases, each of these functions can be represented by a set of spectral parameters such as its amplitude, frequency, phase, and the variability of its instantaneous spectral components. The accuracy of these parameters depends on several processing variables such as resolution, noise level, and bias of the algorithm used. This thesis presents some background of existing frequency estimation techniques and proposes a new technique for estimating the instantaneous frequency of signals using short sinusoid-like basis functions. Furthermore, it also shows that the proposed algorithm can be implemented in a popular embedded DSPmicroprocessor for practical use. This algorithm can also be implemented using more complex features on more resourceful processing processors in order to improve estimation accurac

Constrained Assortment Optimization under the Cross-Nested Logit Model

We study the assortment optimization problem under general linear constraints, where the customer choice behavior is captured by the Cross-Nested Logit model. In this problem, there is a set of products organized into multiple subsets (or nests), where each product can belong to more than one nest. The aim is to find an assortment to offer to customers so that the expected revenue is maximized. We show that, under the Cross-Nested Logit model, the assortment problem is NP-hard, even without any constraints. To tackle the assortment optimization problem, we develop a new discretization mechanism to approximate the problem by a linear fractional program with a performance guarantee of $\frac{1 - \epsilon}{1+\epsilon}$, for any accuracy level $\epsilon>0$. We then show that optimal solutions to the approximate problem can be obtained by solving mixed-integer linear programs. We further show that our discretization approach can also be applied to solve a joint assortment optimization and pricing problem, as well as an assortment problem under a mixture of Cross-Nested Logit models to account for multiple classes of customers. Our empirical results on a large number of randomly generated test instances demonstrate that, under a performance guarantee of 90%, the percentage gaps between the objective values obtained from our approximation methods and the optimal expected revenues are no larger than 1.2%

A Tourists' Travel Intention in the Context of Covid-19 in Viet Nam

The novel coronavirus pneumonia has seriously affected the development of tourism in Vietnam and even the whole world. Combining the current of VietNam's mitigation and the gradual recovery of tourism, this paper puts the research perspective on tourists' travel intention, and constructs a new theoretical structure by using TPB and TRA theory, This study presents the findings of a research which examined the relationship Subject norms and perceived behavioral control have a significant impact on Attitude and tourists' desire to travel;  the Attitude and desire to travel has a significant positive impact on tourists' travel intention, a little empirical study investigates these relationships together. This article investigates these relationships using SEM with data 437 tourists in the Vietnam. Findings of the study revealed that Attitude mediates the relationship between Subject norms, Perceived Behavioral Control, and Travel intention. Desire to travel mediates the relationship between Subject Norm, Perceived Behavioral Control and Travel intention. Based on the study findings, implications for theory and practice are discussed. Keywords: COVID-19, Theory of planned behaviour(TPB), Theory of reasoned action(TRA),Viet Nam DOI: 10.7176/EJBM/13-14-07 Publication date:July 31st 202

Anti-inflammatory activity of methyl ferulate isolated from Stemona tuberosa Lour

AbstractObjectiveTo evaluate the anti-inflammatory activity of methyl ferulate (MF) isolated from the roots of Stemona tuberosa (S. tuberosa) Lour (Stemonaceae) in lipopolysaccharide activated macrophage cells.MethodsMethanol extracts of a root powder of S. tuberosa were prepared for isolation of a potential anti-inflammatory agent using ultrasound extraction combined with repeated chromatography on silica gel. After the quantitative analyses, anti-inflammatory activity of the isolated compound was evaluated by measurement of cytokine release, NO generation, expression of cyclooxygenase-2 and phosphorylation of mitogen activated protein kinases including p38 and c-Jun NH2-terminal kinase using quantitative kits and Western blotting with specific antibodies.ResultsThe isolation process yielded a potential anti-inflammatory compound with a purity level of 99% determined by high performance liquid chromatography. The compound was identified as MF by using nuclear magnetic resonance. MF strongly inhibited the release of pro-inflammatory cytokines from macrophages, including IL-6, TNFα, IFNγ, yet it did not affect the anti-inflammatory cytokine IL-10. Phosphorylation of p38 and c-Jun NH2-terminal kinase were clearly reduced in MF-treated macrophages stimulated with lipopolysaccharide. cyclooxygenase-2 expression and NO generation by macrophages were also suppressed when the cells were treated with MF.ConclusionsThe data suggested that MF is a possible inhibitor of the mitogen activated phosphor kinase pathway and could be a potential anti-inflammatory agent isolated for the first time in medicinal plant S. tuberosa

Experimental and Numerical Evaluation of Concentrically Loaded RC Columns Strengthening by Textile Reinforced Concrete Jacketing

Nowadays, Textile Reinforced Concrete (TRC) has become a very popular strengthening technique for concrete structures. This paper presents an investigation on the applicability of TRC for strengthening reinforced concrete column. Both experimental and numerical studies are conducted to evaluate the confinement effects of various TRC strengthening schemes. The experimental study is performed on a series of six reinforced concrete square columns tested to failure. Two of them were un-strengthened as references, the other four were strengthened by one or two layers of Carbon Textile Reinforced Concrete (CTRC). The results indicated that the application of carbon TRC enhanced the ductility and ultimate strength of the specimens. Failure of all strengthened columns was together with tensile rupture of textile reinforcements at the corners of column. Finite element models of the CTRC strengthened columns based on ATENA software package were developed and verified with the experimental results. The analytical results show that in the specimen corner areas, textile reinforcements are subjected to a 3D complicated stress state and this may be the cause of their premature failure

Linking Ethical Leadership to Employee Creative Performace: The Role of Leader-Member Exchange and Work Engagement

Purpose: The purpose of this research is to investigate the mediating role of leader-member exchange (LMX) and work engagement in the relationship between ethical leadership and creative performance.   Theoretical framework: The study is based on the theoretical foundation that ethical leadership positively influences creative performance. It further posits that this relationship is mediated by both leader-member exchange (LMX) and work engagement.   Design/Methodology/Approach: Data for this study was collected from a Vietnamese service firm, with a sample comprising 78 leaders and 354 employees. The collected data was analyzed using structural equation modeling (SEM) to examine the proposed relationships.   Findings: The findings of the study indicate a significant and positive correlation between ethical leadership and creative performance. Additionally, the study reveals that ethical leadership exerts an influence on both leader-member exchange (LMX) and work engagement, which subsequently enhance employees' demonstration of creativity in their work.   Research, practical & social implications: This research sheds light on the mediating mechanisms through which ethical leadership impacts creative performance. The findings highlight the importance of fostering positive leader-member relationships and promoting work engagement in order to enhance employees' creative behaviors. Practically, the study suggests that organizations should prioritize the development of ethical leadership qualities to foster a creative work environment. Moreover, the research contributes to the broader social implications by emphasizing the significance of ethical leadership in promoting creativity and innovation within organizations.   Originality/Value: This research contributes to the existing literature by examining the mediating role of leader-member exchange and work engagement in the relationship between ethical leadership and creative performance. The study provides valuable insights into the mechanisms through which ethical leaders can enhance creativity in the workplace. The findings of this research contribute to the understanding of the importance of ethical leadership and its impact on organizational outcomes, thereby adding to the originality and value of the study

Carrageenophyte-attached and planktonic bacterial communities in two distinct bays of Vietnam: Eutrophication indicators and insights on ice-ice disease

The composition of the bacterial community of carrageenophyte-attached and planktonic bacteria was studied in two bays of Vietnam with contrasting anthropogenic inputs to assess their role as ecological indicators. Clear differences (~73% dissimilarity) between carrageenophyte-attached bacteria and bacterioplankton were detected in terms of genus composition: mainly Agaribacter, Ruegeria, Alteromonas, the Pir4 lineage and Vibrio for the carrageenophytes and Candidatus Actinomarina, HIMB 11, NS groups and SAR clades for the bacterioplankton. The copiotrophic nature, potential for complex-polymer degradation, and ability to form and defend biofilms were common features inferred for the carrageenophyte-attached microbiome. Significant differences between the bays were detected in the concentration of most inorganic nutrients. More eutrophic conditions and presumptive wastewater pollution in Cam Ranh (CR) bay were primarily indicated by the dominance of Rubripirellula, Leptobacterium, Hypnocyclicus and Porphyrobacter and their correlations with phosphate. In terms of bacterioplankton, the influence of intensive aquaculture in CR bay was suggested by the dominance of the NS5 and NS4 marine groups, the SUP05 cluster, Flavobacteriaceae unclassified and SAR 11 clade III as well as their strong correlations with ammonium and phosphate. The link between silicate and other inorganic nutrients suggests freshwater input in CR bay. Arenicellaceae unclassified and Formosa were also potential indicators of eutrophication. Operational taxonomic units (OTUs) of Marinagarivorans, Cobetia, Vibrio, Alteromonas and Pseudoalteromonas were typical of the carrageenophytes showing ice-ice disease symptoms. Vibrio and Alteromonas were also common among healthy macroalgae, and differences at the OTU level suggested potential succession of species from the healthy to the diseased state. The probable beneficial roles of some bacteria, such as Ruegeria, Cutibacterium and unidentified members of the family Rhizobiaceae, were discussed. This study provides pioneering insights into the bacterial community composition of carrageenophytes and highlights their ecological value as strong indicators of the sources of organic matter, anthropogenic impacts and health status of marine systems.Fil: Kopprio, Germán Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz - Institute of Freshwater Ecology and Inland Fisheries; Alemania. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; VietnamFil: Cuong, Le Huu. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; Vietnam. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; VietnamFil: Luyen, Nguyen Dinh. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; Vietnam. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; VietnamFil: Duc, Tran Mai. Vietnam Academy of Science and Technology. Nhatrang Institute of Technology Research and Application; VietnamFil: Ha, Tran Hong. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; VietnamFil: Huong, Le Mai. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; Vietnam. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; VietnamFil: Gärdes, Astrid. Leibniz - Institute of Freshwater Ecology and Inland Fisheries; Alemania. University of Applied Sciences; Alemania. Alfred-Wegener-Institut. Helmholtz-Zentrum für Polar und Meeresforschung; Alemani

An Updated Loop-Mediated Isothermal Amplification Method for Rapid Diagnosis of H5N1 Avian Influenza Viruses

We designed a new set of primers for reverse transcriptase loop-mediated isothermal amplification (RTLAMP) to specifically amplify the HA gene of avian influenza viruses subtype H5N1. By testing nine H5N1 virus strains and 41 clinical samples collected in Northern Vietnam, we found that the new primers showed higher sensitivity and specificity than the previously published RT-LAMP primers and were comparable to the RT-PCR method currently recommended by WHO. These results suggest that our RT-LAMP assay may be a better choice as a diagnostic tool for current H5N1 influenza virus infection

On Construction of Bit-Interleaved Coded Modulation Systems with Iterative Decoding

A new construction of Bit-Interleaved Coded Modulation systems with Iterative Decoding (BICM-ID) is proposed to achieve the best performance over white additive Gaussian noise (AWGN) channels, assuming that the ideal feedback (IF) holds for iterative decoding. For a class of so-called regular IF mappings, new upper bounds for error probabilities are presented for both cases of BICM-ID systems using overall and in-line interleaving. Search results for component Recursive Systematic Convolutional (RSC) codes with and without puncturing are reported for 4-PSK and 8-PSK signal sets

Combining heterogeneous classifiers via granular prototypes.

In this study, a novel framework to combine multiple classifiers in an ensemble system is introduced. Here we exploit the concept of information granule to construct granular prototypes for each class on the outputs of an ensemble of base classifiers. In the proposed method, uncertainty in the outputs of the base classifiers on training observations is captured by an interval-based representation. To predict the class label for a new observation, we first determine the distances between the output of the base classifiers for this observation and the class prototypes, then the predicted class label is obtained by choosing the label associated with the shortest distance. In the experimental study, we combine several learning algorithms to build the ensemble system and conduct experiments on the UCI, colon cancer, and selected CLEF2009 datasets. The experimental results demonstrate that the proposed framework outperforms several benchmarked algorithms including two trainable combining methods, i.e., Decision Template and Two Stages Ensemble System, AdaBoost, Random Forest, L2-loss Linear Support Vector Machine, and Decision Tree