Ôn thi IELTS

This paper examines the cash holdings behavior of Vietnamese listed companies, focusing on whether a target cash level exists that maximizes firm value and the speed at which firms adjust towards this target. The study finds that the average cash holding for these firms is approximately 10%.

6p viaburame 14-03-2025 2 1   Download

In this paper, the problem of exponential stability of linear time-delay systems with mixed discrete and distributed delays is studied. Based on an asymmetric Lyapunov–Krasovskii functional approach, sufficient conditions are derived in terms of linear matrix inequalities to guarantee the exponential convergence of the system state trajectories with a prescribed decay rate.

14p viaburame 14-03-2025 1 1   Download

Currently, cricket farming is becoming more and more popular since it brings high economic efficiency to farmers. Crickets can be raised in a small area, are easy to care for, have a short harvest time, and have no pollution problem. This paper provides insight into the effects of three types of food on the growth and development of crickets (Gryllus bimaculatus) and proposes the rearing process of crickets.

10p viaburame 14-03-2025 2 1   Download

This article presents the frequency and trends of meteorological drought in Thai Binh province for the period 1991-2021 and forecasts drought trends for the period 2025-2065 based on climate change scenarios. The PED drought index is calculated using the corresponding daily temperature and rainfall data for each of these periods.

11p viaburame 14-03-2025 1 0   Download

This paper presents optimization results of the Al6061 surface roughness in turning ultra-precision based on the central composite design method (CCD) and the grey wolf optimization algorithm (GWO). The experimental matrix is built with three independent variables including spindle speed, feed rate and depth of cut. With the experimental data, the roughness regression model is established.

7p viaburame 14-03-2025 1 1   Download

Red phosphorus is an important ingredient in the manufacture of pyrotechnic smoke and is likely to be in service for many years. One of the most effective ways to use smoke screens is to protect special vehicles from laser and infrared guidance systems. In this work, the formulation, obscurant and emission characteristics of the smoke composition in smoke devices used in special vehicles were determined and evaluated.

11p vinatis 30-07-2024 4 2   Download

Hypertrophic cardiomyopathy (HCM) is a common genetic cardiovascular disease and a major cause of sudden death. It is also involved in increasing morbidity and mortality of various cardiovascular diseases. Genetic factors have been found to be important in determining the phenotypic manifestation of cardiac hypertrophy. However, only 50–60% of HCM patients have been identified as having pathogenic variants in known genes, suggesting that more studies are needed to find more disease genes.

15p xuanphongdacy06 18-09-2024 6 1   Download

Air pollution is getting worse in Viet Nam in recent years, particularly in big cities. The most important source of pollution are traffic and industrial activities. The paper "A Review on Current Status of Urban Air Pollution in Ho Chi Minh city and Ha Noi" reviews air pollution situation in Ho Chi Minh city and Ha Noi. We also recommend policies to tackle the problem: (i) upgrade the national air quality standard, (ii) install systematic and high-quality network of monitor stations, and (iii) remove means of transport that unmet emission regulations.

11p xuanphongdacy09 29-09-2024 3 1   Download

In recent years, the understanding of processes on material surfaces has drawn considerable interest from scientists. The adsorption stage is important for further insights into surface interactions and photocatalytic reactions. In this study, we use density functional theory computations to investigate the adsorption of sulfamethoxazole (SMX) molecules on the rutile-TiO2 (001) surface (r-TiO2 ).

8p viyoko 01-10-2024 3 1   Download

This study aims to contribute to the development of a GaN/Ga2O3 diode that can be utilized in high-power device applications. The simulated device is calibrated against experimental GaN and Ga2O3 diodes, considering the effect of thickness of GaN layer and its doping concentration on the performance of GaN/Ga2O3 diodes. The band structures of devices are investigated to revial which factors that affect the properties of GaN/Ga2O3 diode.

6p viling 11-10-2024 5 1   Download

Disposed batteries contain the hazardous sources that directly impact on the environment. Proper disposal of used batteries is a vital matter because of toxit component found in types of batteries. This study focuses on the reutilization of the disposed Zn-battery graphite to produce graphene oxide (GO) via electrochemical exfoliation.

8p viling 11-10-2024 4 1   Download

In mathematics, a conic section (or just conic) is a curve obtained as the intersection of a cone (more precisely, a right circular conical surface) with a plane. In this paper "Some new identities on the conic sections", we construct some new identities and proposed the concept of the power of a point with respect to a conic.

12p runordie3 27-06-2022 8 4   Download

Seed propagation of Mycetia balansae Drake is not easy, due to low germination rate and low viability, so it is very rare in nature. In order to conserve this plant as well as to use for commercial purposes in cooperation with Tue Linh Co.Ltd, providing a large number of plants is necessary and in vitro tissue culture technology could be solve this problem. Therefore, the study on "Callus induction and plant regeneration in vitro from leaf explants of mycetia balansae drake" was carried out.

8p xuanphongdacy09 29-09-2024 4 1   Download

This paper is devoted to the study of existence, uniqueness and other properties of solutions of a 3-order nonlinear integrodifferential equation (IDE) in three variables in an arbitrary Banach space.

12p viengfa 28-10-2024 4 2   Download

This paper investigates the problem of finite-time stability for discrete-time neural networks with sector-bounded neuron activation functions and interval-like timevarying delay. The extended reciprocally convex approach is used to establish a delay-dependent sufficient condition to ensure finite-time stability for this class of systems.

12p viling 11-10-2024 1 1   Download

The fuzzy time series model has become a research topic attracting attention because of its practical value in the field of time series forecasting, specifically, it is useful for time series with small observations or the one of strong fluctuations. This paper introduces a fuzzy time series model based on hedge algebra with a new formula for calculating forecasting values.

9p viengfa 28-10-2024 2 1   Download

In this study, the researcher focuses on exploring the impact of the European Union–Vietnam Free Trade Agreement and the European Green Deal on Vietnamese exports. This article used qualitative methods, including collecting and analyzing secondary data. The objective is to understand the requirements and standards set by the European market and the advantages that the free trade agreement impacts on the quality and competitiveness of Vietnamese export products.

16p viengfa 28-10-2024 3 0   Download

Creating credit is the main income-generating activity for banks. However, granting credit always comes with risks. Credit risk is the risk of losing part or all of a debt due to failure to pay on time or default. Credit risk is considered the most important risk affecting banking performance. Therefore, this study measured the effect of credit risk on the financial performance of Vietnamese commercial banks.

13p vibecca 01-10-2024 4 1   Download

Iceberg lettuce is one of the most important vegetables economically and nutritionally, but its perishable nature poses challenges for storage and long-distance transportation. This study investigated the effect of maturity stages on the quality of iceberg lettuce for export under cold storage conditions.

12p vibecca 01-10-2024 2 2   Download

The score function is used to compare intutionistic fuzzy numbers. In this paper, a novel score function of intuitionistic fuzzy sets (IFSs) is investigated. The novel score function was constructed by combining the polynomial and exponential functions working on the degree of membership and degree of non-membership of intuitionistic fuzzy sets.

11p vibecca 01-10-2024 4 1   Download