Estimation of Sand Production Rate Using Geomechanical and Hydromechanical Models

This paper aims to develop a numerical model that can be used in sand control during production phase of an oil and gas well. The model is able to predict not only the onset of sand production using critical bottom hole pressure inferred from geomechanical modelling, but also the mass of sand produced versus time as well as the change of porosity versus space and time using hydromechanical modelling. A detailed workflow of the modelling was presented with each step of calculations. The empirical parameters were calibrated using laboratory data. Then the modelling was applied in a case study of an oilfield in Cuu Long basin. In addition, a sensitivity study of the effect of drawdown pressure was presented in this paper. Moreover, a comparison between results of different hydromechanical models was also addressed. The outcome of this paper demonstrated the possibility of modelling the sand production mass in real cases, opening a new approach in sand control in petroleum industry

Research on the influence mechanism of the target countries’ public opinion on Chinese firms’ cross-border mergers and acquisitions and Chinese firms’ coping strategy——A multi-case study

随着中国经济实力的日益增强，越来越多的中国企业走出国门，掀起了一股股中国企业海外并购的热潮。对于企业海外并购这一研究主题，学者们较多关注的是中国企业在海外并购后的整合问题，而对于竞购过程中所面临的舆论干扰问题关注得比较少。因此，本文重点聚焦于以下几个核心问题：中国企业海外并购过程如何受到目标国所在的社会大众舆论的影响？具体有哪些非商业因素影响到中国企业跨国并购的成败？针对目标国社会舆论在并购过程中对中国企业的潜在负面影响，有哪些具体应对措施？ 首先，本文重点针对目标国社会舆论对中国企业海外竞购的影响机理进行现有文献和学术成果的理论综合，分析和论述。其次，选择了4个典型的中国企业海外并购的案例...With China’s remarkably growing economy, an increasing number of Chinese enterprises are going abroad, leading to a boom of Chinese enterprises’ cross-border mergers and acquisitions (M&A). With regard to the topic of cross-border M&As, the majority of scholars have mainly focused on the post-acquisition integration issues of Chinese enterprises, but little on the tough public opinions issues that...学位：管理学硕士院系专业：管理学院企业管理系_企业管理(含财务管理、市场营销、人力资源管理)学号：1762011115422

Self-reported worry and action among Vietnamese citizens during the COVID-19 pandemic in 2021: latent class analysis

Describe the prevalence of and factors associated with self-reported worry and actions of Vietnamese citizens during the COVID-19 pandemic in 2021. A secondary data analysis was implemented using a cross-sectional survey conducted in 2021 among 447 adults living in Hanoi City from July to December 2021 and Ho Chi Minh City from May to October 2021. The hidden layers assessment results retained the 3-class model as the best-fitting one in the study. In this model, 28.4% of participants were in Class 2 - "Low Self-reported Worry and Moderate Action" group, 45.9% of the participants were classified into Class 1-"Moderate Self-reported Worry and Low Action" group, and 25.7% in Class 3 - "High Self-reported Worry and High Action" group. The multinomial logistics model showed that worrying about losing the house because of COVID-19 makes the expected participation risk of staying in latent class 1 lower for subjects high in latent class 3 (p<0.05). Our study identified the latent classes of self-protection action and awareness among Vietnamese citizens. The associated factor that impacted the classes was the fear of losing a house

“False Patellar Duplication†Originated from Synovial Osteochondromatosis in Knee Joint: A Rare Case Report

BACKGROUND: “False patellar duplication†is a situation where there are two pieces in the position of a knee-joint like patella. It can derive from cartilage tumors, soft tissue tumors, or gout tumors, or due to the heterotopic ossification, forming a sub patella in the knee joint. CASE REPORT: A woman, 57 years old, healthy history, she has hospitalized for right knee joint pain since 2 years. Diagnosis: the synovial osteochondromatosis of the right knee. We decided to conduct and arthroscopy and removal. After 18 months surgery, the patient knee joint is currently good, range of motion (ROM) (-10)°- 0°-160°, Lysholm Knee Scoring Scale 85/100 point. CONCLUSION: This is the second case in the world and the first case in Vietnam. This is an experience in the process of diagnosis, arthroscopic treatment and differentiation from the "double patellae" status

Coderivatives at infinity of set-valued mappings

In this paper, the concept of coderivatives at infinity of set-valued mappings is introduced. Well-posedness properties at infinity of set-valued mappings as well as Mordukhovich's criterion at infinity are established. Fermat's rule at infinity in set-valued optimization is also provided. The obtained results, which give new information even in the classical cases of smooth single-valued mappings, provide complete characterizations of the properties under consideration in the setting at infinity of set-valued mappings

Effect of Different Types of Liquid Natural Rubbers on the Modification of DGEBA-Based Epoxy Resin

Diglycidyl ether of bisphenol A (DGEBA)-based epoxy and varying content of hydroxyl terminated liquid natural rubber (HTNR) or carboxyl-terminated liquid natural rubber (CTNR) were cured using an aromatic amine hardener. The ultimate aim of the study was to modify the brittle epoxy matrix by liquid rubber to improve the toughness characteristics. Tensile, flexural, and fracture toughness behaviors of neat as well as modified networks have been studied to observe the effect of different types of  liquid natural rubber modification. The morphological evolution of the toughened networks was examined by scanning electron microscope (SEM), and the observations were used effectively to explain the impact properties of the network having varying content of liquid natural rubbers. The results showed that the impact resistance of both HTNR-modified DGEBA and CTNR-modified DGEBA was superior to that of the pure epoxy resin, among which the impact resistance of CTNR-modified DGEBA was better than that of HTNR-modified DGEBA. For all the composites with HTNR or CTNR, the impact resistance increased with elastomer concentration up to 15.0 parts per hundred parts of resin (phr). Higher concentration of the elastomers resulted in larger particles and gave lower impact values. These results allow the conclusion that 15 phr is the maximum content of HTPB or CTNR that might be added in DGEBA composites for a positive effect upon the impact strength

Anatomical Study of Femoral Condylar Index in Magnetic Resonance Imaging: Implication to Total Knee Replacement Surgery for Vietnamese People

BACKGROUND: The femoral rotation angle is important element in total knee replacement (TKR). AIM: To measure this angle, we determine through the axes: the transepicondylar axis (cTEA and sTEA), the posterior condylar axis (PCA), the anteroposterior axis (APA – Whiteside axis). METHODS: Measuring the angles created by the four axes: cTEA, sTEA, PCA and APA in magnetic resonance imaging (MRI); determining the femoral rotation angle and application TKR. RESULTS: the angle between APA and cTEA: 90.41° ± 3.35°, the angle between APA and sTEA: 94.47° ± 3.31°, the angle between APA and PCA: 96.40° ± 4.59°, the angle between cTEA and sTEA: 4.00° ± 1.02°, the angle between cTEA and PCA: 6.53° ± 2.55°, the angle between sTEA and PCA: 3.48° ± 1.91°. CONCLUSION: The angle between sTEA and PCA is the angle that best represents the femoral rotation angle. However, in case of sTEA or PCA is difficult to identify, it can be measure via the APA or cTEA. These angles don’t differ by age, gender and place of knee joint

Criblage virtuel sur grille de composés isolés au Vietnam

Criblage virtuel sur grille de composés isolés au Vietna

Isolation and identification of phenolic compounds from the leaf extract of Cassia alata L.

Cassia alata is one of the most important species of the genus Cassia which is rich in anthraquinones and polyphenols. This plant is used as a medicinal material of which the leaves are known to have laxative and antibiotic properties. In our study, the methanol leaf extract of C. alata showed a significant antibacterial activity against human pathogenic bacteria strains Staphylococcus aureus and Bacillus cereus. The organic layers such as n-hexane, ethyl acetate, and aqueous layers, were prepared by partitioning the methanol extract with n-hexane and ethyl acetate successively.  We successfully isolated and identified the structures of five compounds from C. alata leaves. Their structures were elucidated by MS and NMR spectroscopic methods as well as comparison with literature data. These compounds were determined to be methyl 2,4,6-trihydroxybenzoate (1), kaempferol (2), (-)epiafzelechin (3), kaempferol-3-O-glucoside (4) and kaempferol-3-O-gentiobioside (5). Keywords. Cassia alata L., epiafzelechin, kaempferol, kaempferol-3-O-glucoside, kaempferol-3-O-gentiobioside