Experimental Investigation of the Muzzle Blast for the Amphibious Rifles when Shooting Underwater

Designed for amphibious combat forces, the amphibious rifle is a revolutionary new kind of weapon. This firearm's design and the determination of the effect of shooting on the shooter are both dependent on the development of the underwater muzzle blast. In this work, an experiment to evaluate the muzzle blast overpressure and gas bubble characteristics of an amphibious rifle when shooting underwater is performed in order to better understand the weapon's capabilities. This inquiry is focused on the 5.56 mm amphibious rifle with 5.56x45 mm underwater ammunition. The results of the experiments indicated that the Rayleigh-Plesset equation may be used to describe and predict the size of gas bubbles. The experimental data may be utilized to compute the law of change of overpressure based on the experimental results. Also, it is a very important base for studying, designing, making, and mastering weapon technology, which are all very important steps in the development of weapon technolog

NONLINEAR PROPERTIES OF STRUCTURAL HETEROGENEOUS PHOTONIC CRYSTAL FIBERS WITH As2Se3 SUBSTRATE

We examine the possibility of improving the nonlinear properties of photonic crystal fibers (PCFs) with As2Se3 substrates by creating a difference in the diameters of the air holes of the rings around the core. With the new design, all-normal dispersion properties, small effective mode area, high nonlinear coefficient, and low confinement loss were achieved in the long-wavelength range of 2.0–7.0 µm. The highest nonlinear coefficient is 4414.918 W-1.km-1 at 4.5 µm for the lattice constant (Ʌ) of 3.0 µm and the filling factor (d/Ʌ) of 0.85, while the lowest loss is 1.823´10-21 dB/cm with Ʌ = 3.5 µm and d/Ʌ = 0.8. Based on the numerical simulation results, the characteristics of two optimal structures have been analyzed in detail to guide the application in supercontinuum generation

Эмпирическое исследование взаимосвязи между реальным валютным курсом, экспортом и экономическим ростом во Вьетнаме

The article focuses on qualitative and quantitative analysis of the relation between real effective exchange rate, export and economicgrowth in Vietnam. The qualitative analysis results showed that economic growth, real effective exchange rate and export in Vietnam tend to fl uctuate in the same direction. Besides, the estimation result of VECM indicated that economic growth promoted export growth through higher productivity and competitive advantages of products and real exchange rate. Thus, economic growth had a positive impact on export in Vietnam.В статье рассматриваются качественный и количественный анализ соотношения между реальным эффективным валютным курсом, экспортом и экономическим ростом во Вьетнаме. Результаты качественного анализа показали, что экономический рост, реальный эффективный валютный курс и экспорт во Вьетнаме, как правило, колеблются в одном и том же направлении. Кроме того, результаты оценки VECM показывают, что экономический рост способствует росту экспорта за счет повышения производительности и конкурентных преимуществ продукции и реального валютного курса. Таким образом, экономический рост оказал положительное влияние на экспорт во Вьетнаме

Informações contábeis e retornos de ações no mercado de ações do Vietnã: abordagem de aprendizado de máquina

This paper studies the relationship between accounting information reflected in financial statements and stock return in Vietnam Stock Market. The authors propose a research model to define the relationship. Besides, machine learning algorithms are used in researching and forecasting, with data obtained from observed firms during the period from 2009 to 2020. Research results show that gradient boosting algorithm has the best self-reporting performance and finan-cial ratios also have great impact on stock returns, including operating income growth, stock earnings volatility, dividend yield, earnings before tax-to-equity ratio, cash holding ratio, and accrual quality. Based on the research results, the authors make some recommendations for investors, firms, and policy makers.Este artículo estudia la relación entre la información contable reflejada en los estados financieros y el rendimiento de las acciones en el mercado de valores de Vietnam. Se propone un modelo de investigación para definir la relación. Además, los algoritmos de aprendizaje automático se utilizan en la investigación y la previsión, con datos obtenidos de empresas observadas durante el período de 2009 a 2020. Los resultados de la investigación muestran que el algoritmo gradient boosting tiene el mejor rendimiento de autoinforme y los índices financieros también tienen un gran impacto en la rentabilidad de las acciones, al incluir el crecimiento de los ingresos operativos, la volatilidad de las ganancias de las acciones, el rendimiento de los dividendos, la relación entre las ganancias antes de impuestos y el capital, la relación de tenencia de efectivo, y la calidad de la acumulación. Sobre la base de los resultados de la investigación, se hacen algunas recomendaciones para inversionistas, empresas y formuladores de políticas.Este artigo estuda a relação entre as informações contábeis refletidas nas demonstrações financeiras e o retorno das ações no mercado de ações do Vietnã. Os autores propõem um modelo de pesquisa para definir a relação. Além disso, algoritmos de aprendizado de máquina são usados em pesquisas e previsões, com dados obtidos de empresas observadas durante o período de 2009 a 2020. Os resultados da pesquisa mostram que o algoritmo gradient boosting tem o melhor desempenho de autorrelato e os índices financeiros também têm grande impacto nos retornos das ações, incluindo crescimento da receita operacional, volatilidade do lucro das ações, rendimento de dividendos, lucro antes do índice de impostos sobre o patrimônio líquido, índice de retenção de caixa e qualidade de acumulação. Com base nos resultados da pesquisa, os autores fazem algumas recomendações para investidores, empresas e formuladores de políticas

TOTAL PHENOLIC CONTENT, ANTIOXIDANT CAPACITY AND STARCH HYDROLYTIC ENZYME INHIBITION OF THE EXTRACTS FROM UNPOLISHED COLORED RICES

The different colors of rice are contributed by various phenolic compounds, which have various health benefits. However, phenolic compounds, which are mostly existed in rice bran and easily lost during milling. Therefore, the consumption of unpolished rice is recommended to prevent from many diseases. The objective of this study is to determine total phenolic and flavonoid contents, antioxidant capacity and diabetic enzyme inhibition potential of the extracts of the different unpolished colored rices. Three kinds of unpolished colored rices (unpolished white rice, unpolished red rice and unpolished black rice) grown in Vietnam were used to extract their bioactive compounds by alcoholic solvent extracting method. The results showed that the highest level of total phenolic content (TPC) was found in unpolished red rice (470.96 µg FAE/g db sample), while the lowest was in unpolished white rice (135.84 µg FAE/g db sample). TPC of rice in free form was considerably higher than that in the bound form. Total flavonoid content in free form was also significantly higher than bound form. Total flavonoid content in free form of unpolished black rice (126.75 µg RE/g db sample) was higher than that in the others. In the present study, unpolished red rice extract possessed the best antioxidant activity (78.79%) in most cases, and showed the strongest inhibitory potential against alpha-amylase (78.56%) and amyloglucosidase (36.13%) as well. As a result, extracts of unpolished colored rices could act like both antioxidant and enzyme inhibitors and have a potential to be used in prevention of type 2 diabetes

Anharmonic EXAFS and its Parameters of HCP Crystals: Theory and Comparison to Experiment

A new theory for ab initio calculation of the anharmonic Extended X-ray Absorption Fine Structure (EXAFS) and its parameters of hcp crystals has been developed based on the single- shell model. Analytical expressions for the anharmonic contributions to the amplitude and to the phase of EXAFS and a new anharmonic factor have been derived. The EXAFS cumulant expressions are formulated based on the anharmonic correlated Einstein model. The EXAFS function and its parameters contain anharmonic effects at high temperature and appoach those of the harmonic model at low temperature. Numerical results for Zn agree well with the experimental values

Attention correlated appearance and motion feature followed temporal learning for activity recognition

Recent advances in deep neural networks have been successfully demonstrated with fairly good accuracy for multi-class activity identification. However, existing methods have limitations in achieving complex spatial-temporal dependencies. In this work, we design two stream fusion attention (2SFA) connected to a temporal bidirectional gated recurrent unit (GRU) one-layer model and classified by prediction voting classifier (PVC) to recognize the action in a video. Particularly in the proposed deep neural network (DNN), we present 2SFA for capturing appearance information from red green blue (RGB) and motion from optical flow, where both streams are correlated by proposed fusion attention (FA) as the input of a temporal network. On the other hand, the temporal network with a bi-directional temporal layer using a GRU single layer is preferred for temporal understanding because it yields practical merits against six topologies of temporal networks in the UCF101 dataset. Meanwhile, the new proposed classifier scheme called PVC employs multiple nearest class mean (NCM) and the SoftMax function to yield multiple features outputted from temporal networks, and then votes their properties for high-performance classifications. The experiments achieve the best average accuracy of 70.8% in HMDB51 and 91.9%, the second best in UCF101 in terms of 2DConvNet for action recognition

Large-scale Vietnamese point-of-interest classification using weak labeling

Point-of-Interests (POIs) represent geographic location by different categories (e.g., touristic places, amenities, or shops) and play a prominent role in several location-based applications. However, the majority of POIs category labels are crowd-sourced by the community, thus often of low quality. In this paper, we introduce the first annotated dataset for the POIs categorical classification task in Vietnamese. A total of 750,000 POIs are collected from WeMap, a Vietnamese digital map. Large-scale hand-labeling is inherently time-consuming and labor-intensive, thus we have proposed a new approach using weak labeling. As a result, our dataset covers 15 categories with 275,000 weak-labeled POIs for training, and 30,000 gold-standard POIs for testing, making it the largest compared to the existing Vietnamese POIs dataset. We empirically conduct POI categorical classification experiments using a strong baseline (BERT-based fine-tuning) on our dataset and find that our approach shows high efficiency and is applicable on a large scale. The proposed baseline gives an F1 score of 90% on the test dataset, and significantly improves the accuracy of WeMap POI data by a margin of 37% (from 56 to 93%)

AGING OF WATERBORNE PAINT BASED ON THE ACRYLIC RESIN EMULSION AND ORGANIC PIGMENT

Aging of waterborne paint on the base of acrylic resin emulsion with and without green Luconyl have been investigated by general appearance assessment, adhesion change, FT-IR and discoloration. The obtained results showed that the both of paint-formulas coatings had no cracks, blisters, flacks and there was no change of adhesion during the aging process. However, IR analysis indicated that there were some changes in chemical structures of coating with and without Green Luconyl during aging process. To specify, IR spectrums of initial and aged coating no containing Green Luconyl illustrated aging process led content of O-H and C=C increased significantly but baseline of spectra was fairly unchanged. For coating filled Green Luconyl, IR spectrums’ shape was fairly stable but baseline saw a clear reduce during accelerated weather exposure. Moreover, SEM images indicated that surfaces morphology of samples changed differently depending on in presence of organic pigment. Surface of aged coating without Luconyl saw rougher than surface of coating with Luconyl after aging process. Hence, the weather aging test had more significant influence on paint coating in absence of Luconyl than paint coating in presence of Luconyl. It was explained that the macroradical produced in aging process would attack into conjugated double bonds of Luconyl instead of double bonds of AC-261 leading to aged coating filled Luconyl become more opaque than initial while coating no filled Luconyl had significant changes in chemical structure during aging process. Although this was a hypothesis, it saw a suitable with the obtained results. The paint coating in presence of Luconyl illustrated significant color change, especially, showed the loss of green color while the other paint coating showed slight color change

Analyzing the Determinants of Services Trade Flow between Vietnam and European Union: Gravity Model Approach

This paper aims at analyzing the determinants of services trade flows between Vietnam and European Union. In this respect, a gravity model has been estimated with panel data and pooled, random and fixed effect estimation covering the period of ten years from 2002 to 2011 for total services trade, services exports and services imports between Vietnam and European Union separately. The estimated results on total services trade indicate that bilateral services trade flows between Vietnam and its European partner countries are mainly affected by GDP per capita gap between Vietnam and partner countries, population of partner countries, real effective exchange rate, colonial relationship and being former members of CMEA