Model reduction of unstable systems based on balanced truncation algorithm

Model reduction of a system is an approximation of a higher-order system to a lower-order system while the dynamic behavior of the system is almost unchanged. In this paper, we will discuss model order reduction (MOR) strategies for unstable systems, in which the method based on the balanced truncation algorithm will be focused on. Since each MOR algorithm has its strengths and weakness, practical applications should be suitable for each specific requirement. Simulation results will demonstrate the correctness of the algorithms

Weak Lefschetz property of graded Gorenstein algebras associated to the Apéry set of a numerical semigroup

It has been conjectured that all graded Artinian Gorenstein algebras of codimension three have the weak Lefschetz property over a field of characteristic zero. In this paper, we study the weak Lefschetz property of associated graded algebras A of the Apéry set of M-pure symmetric numerical semigroups generated by four natural numbers. These algebras are graded Artinian Gorenstein algebras of codimension three

Some algorithms related to consistent decision table

Rough set theory is useful mathematical tool developed to deal with vagueness and uncertainty. As an important concept of rough set theory, an attribute reduct is a subset of attributes that are jointly sufficient and individually necessary for preserving a particular property of the given information table. Rough set theory is also the most popular for generating decision rules from decision table. In this paper, we propose an algorithm finding object reduct of consistent decsion table. On the other hand, we also show an algorithm to find some attribute reducts and the correctness of our algorithms is proof-theoretically. These our algorithms have polynomial time complexity. Our finding object reduct helps other algorithms of finding attribute reducts become more effectively, especially as working with huge consistent decision table

Condensation Heat Transfer of R410A Inside Multiport Minichannels with Different Cross-sectional Geometry

Condensation heat transfer of R410a in a multiport mini-channels tubes with different cross-sectional geometry is experimentally investigated. Three tubes with aspect ratio of 0.395, 0.385 and 0.446, and hydraulic diameters of 1.147 mm, 1.135 mm and 0.846 mm with number of channels (7, 11 and 18) are tested in this study. The experimented range of heat flux is from 3 to 15 kW/m2, mass flux from 50 to 500 kg/m2s. The data show that the heat transfer coefficient increases with heat flux, mass flux and vapor quality. A performance comparison was conducted among the 3 tested tubes and it was found out that the number of channels increases heat transfer coefficient significantly at low heat flux and mass flux, while this effect is damped at higher heat/mass flux condition. In addition, it was found that heat transfer in small hydraulic diameter and high aspect ratio channels deteriorated. Possible mechanism to this deterioration is proposed. Finally, a new correlation is developed to predict the heat transfer coefficient of R410a in a multiport mini-channels tube

The lasting effects of innovation on firm profitability: panel evidence from a transitional economy

This study is the first to study the lasting effects of innovation on firm profitability in Vietnam. Using a unique panel dataset for the period 2005–2015, our results show that innovators achieve higher profit in comparison with non-innovating firms. The positive effects of innovation on firm profitability are observed not only in the short term but also in the longer term. The benefits of innovation for firm profitability can be seen in higher export probability, better productivity, better access to formal credit, and the ability to secure government support, but only after innovation

EXTRACURRICULAR SPORTS: POPULAR CONTENTS AND FORMS AMONG STUDENTS IN THE DORMITORY OF VIETNAM NATIONAL UNIVERSITY HO CHI MINH CITY

This article is written to provide thorough information about popular contents and forms of extracurricular sports performed by university students at a dormitory of Vietnam National University Ho Chi Minh City (VNUHCMC). The study uses document references, surveys, and statistical mathematics to investigate what extracurricular sports are favored by the students and how they organize their practices. The results indicate that the majority of students choose to practice football, volleyball, badminton, athletics, and martial arts. They play with themselves and/or in teams, without instructors, from 30 minutes to 02 hours in the afternoon after school time and/or in the morning, at the dormitory and/or sports centers.  Article visualizations

PHYSICAL CONDITION OF MALE STUDENTS AT VIETNAM NATIONAL UNIVERSITY OF HO CHI MINH CITY DORMITORY

The purpose of the study is to provide information about the current physical condition of 19-year-old male students of the Vietnam National University of Ho Chi Minh City (VNUHCMC) dormitory. The research used the methods of synthesizing sport-related documents, interviewing experts, applying pedagogical tests, and statistical analysis to determine appropriate physical fitness assessment tests. Afterward, the figures for the physical condition of male students at the VNUHCMC dormitory were compared with that of the average Vietnamese people, of Hanoi National University (HNU), University of Danang (UD), Can Tho University (CTU), and Ho Chi Minh City (HCMC) students at the same age and gender, and with the standard shown in Decision 53/2008/BGDDT of the Ministry of Education and Training. The results show that the “good” group accounts for 28.75%, the “acceptable” group for 23.19% and the “failed” group for 48.06%. It is notable that the agility, leg muscular strength, endurance, and motor skills of 19-year-old male students at the VNUHCMC dormitory are greater than the average physical fitness of Vietnamese people, as well as students of the same age and gender at HNU, UD, and CTU. Their endurance is also higher than that of male HCMC pupils of the same age, but their leg muscular strength and motor abilities are almost comparable.  Article visualizations

Sub-National Institutions and Firm Survival in Vietnam

By combining two sets of survey data - provincial competitiveness index (PCI) from VNCI-VCCI and USAID and annual enterprise census from Vietnam General Statistics Office (GSO) for the period between 2005 and 2011, we estimate the effects of sub-national institutions measured by Provincial Competitiveness Index on firm survival in Vietnam. Our results show that sub-national institutions have a positive effect on firm’s survival in both short-run and long-run. The effect, however, diminishes over time, indicating that newly entered firms are more likely to survive

Sub-National Institutions and Firm Survival in Vietnam

By combining two sets of survey data - provincial competitiveness index (PCI) from VNCI-VCCI and USAID and annual enterprise census from Vietnam General Statistics Office (GSO) for the period between 2005 and 2011, we estimate the effects of sub-national institutions measured by Provincial Competitiveness Index on firm survival in Vietnam. Our results show that sub-national institutions have a positive effect on firm’s survival in both short-run and long-run. The effect, however, diminishes over time, indicating that newly entered firms are more likely to survive