Optimization of Superplastic Forming Process of AA7075 Alloy for the Best Wall Thickness Distribution

This work aims to optimize the process parameters for improving the wall thickness distribution of the sheet superplastic forming process of AA7075 alloy. The considered factors include forming pressure p (MPa), deformation temperature T (°C), and forming time t (minutes), while the responses are the thinning degree of the wall thickness ε (%) and the relative height of the product h*. First, a series of experiments are conducted in conjunction with response surface method (RSM) to render the relationship between inputs and outputs. Subsequently, an analysis of variance (ANOVA) is conducted to verify the response significance and parameter effects. Finally, a numerical optimization algorithm is used to determine the best forming conditions. The results indicate that the thinning degree of 13.121% is achieved at the forming pressure of 0.7 MPa, the deformation temperature of 500°C, and the forming time of 31 minutes

Factors Affecting Demand for Accounting Services of Enterprises Using Cloud Accounting in Hanoi

Purpose: The article analyzes the impact of factors affecting the demand for accounting services of enterprises using cloud accounting in Hanoi.   Theoretical framework: This paper uses model Factors Affecting Demand for Accounting Services of Enterprises Using Cloud Accounting.   Design/Methodology/Approach: The research method uses a questionnaire survey of accountants, chief accountants, business managers of enterprises in Hanoi. After the survey results are available, data processing is performed by statistical methods to determine the weight and frequency of the selected factors, and the data is processed on SPSS statistics 25 software to estimate the impact of the selected factors, factors affecting the demand for accounting services of enterprises using cloud accounting in Hanoi.   Findings: Research results show that Cost Of Using Accounting Service, Trademark, Introduction, Accounting Professional Qualification, Benefits Of Using Accounting Services, Characteristics Of Businesses Using Cloud Accounting, Supplier's Support have a positive impact on the demand for accounting services of enterprises. businesses using cloud accounting in Hanoi.   Research, practical   &   social   implications: Based on the research results, the author has proposed recommendations to improve the demand for accounting services of businesses using cloud accounting in Hanoi.   Originality/Value: This study fills the gap in the Demand for Accounting Services of Enterprises Using Cloud Accounting in Hanoi

Modeling of parallel power MOSFETs in steady-state

In high-power applications, multiple power MOSFETs are connected in parallel and treated as a single switch in order to handle much larger total currents. In this paper, a parallel power MOSFETs model from the turnoff state until they reach their steady state is introduced. The model represents the relationship between each power MOSFET's gate voltage and the current distribution among them. The study's key purpose is to use the model for dealing with the asymmetry in sharing current and power loss between these semiconductor devices during the steady state region.Comment: 10 pages, 7 figures, The 2023 INTERNATIONAL SYMPOSIUM ON ADVANCED ENGINEERING (ISAE2023

Multi-layer heterogeneous ensemble with classifier and feature selection.

Deep Neural Networks have achieved many successes when applying to visual, text, and speech information in various domains. The crucial reasons behind these successes are the multi-layer architecture and the in-model feature transformation of deep learning models. These design principles have inspired other sub-fields of machine learning including ensemble learning. In recent years, there are some deep homogenous ensemble models introduced with a large number of classifiers in each layer. These models, thus, require a costly computational classification. Moreover, the existing deep ensemble models use all classifiers including unnecessary ones which can reduce the predictive accuracy of the ensemble. In this study, we propose a multi-layer ensemble learning framework called MUlti-Layer heterogeneous Ensemble System (MULES) to solve the classification problem. The proposed system works with a small number of heterogeneous classifiers to obtain ensemble diversity, therefore being efficiency in resource usage. We also propose an Evolutionary Algorithm-based selection method to select the subset of suitable classifiers and features at each layer to enhance the predictive performance of MULES. The selection method uses NSGA-II algorithm to optimize two objectives concerning classification accuracy and ensemble diversity. Experiments on 33 datasets confirm that MULES is better than a number of well-known benchmark algorithms

Development of a nutritional model to define the energy and protein requirements of cobia, Rachycentron canadum

This study assessed the protein and energy requirements of Cobia (Rachycentron canadum) using a bio-energetic factorial approach. Using a series of inter-related studies, several parameters were defined to enable the construction of a bio-energetic factorial model for this species. The studies included two controlled laboratory experiments and also extensive field-data collection from commercial and research farms in Vietnam. The devised model includes parameters for both maintenance and protein demands; the effect of fish live-weight on maintenance protein (LW0.697), lipid (LW0.972), and energy demands (LW0.815); the efficiencies of protein, lipid and energy utilisation at various protein, lipid and energy intake levels; and the variability in whole body composition with varying live-weight. The protein utilisation efficiencies (0.456·[protein intake]−0.445), lipid utilisation efficiencies (1.292·[lipid intake]−1.120) and energy utilisation efficiencies (0.651·[energy intake]−48.41) were similar to other carnivorous fish species. However, the maintenance requirements for both energy (74.3kJ/kgBW0.8/d−at 28°C) and protein (0.99g/kgBW0.7/d at 27.9°C) were about double to other species. Using this modelling approach it was possible to iteratively derive optimal dietary protein and energy specifications for this species

First record of Cantharellus minor from Vietnam with identification support from a combination of nrLSU and nrSSU phylogenetic analysis

Background: A previously identified sample XC02, which was collected from a pine forest (Pinus kesiya Royle ex Gordon), in Xuan Tho Commune, Da Lat, Lam Dong Province, Vietnam, was identified as Cantharellus minor based on morphology and nrLSU phylogeny analysis. Sequence analysis of multiple genes are becoming more and more common for phylogenetic analysis of mushrooms.Method: Total DNA was isolated from sample XC02. The primer NS1, NS4 were applied to amplify the target gene the nuclear ribosomal small subunit DNA (nrSSU). For phylogenetic analysis, individual and concatenated datasets (nrSSU and nrLSU-nrSSU) were constructed. Phylogenetic tree was constructed with MEGA 6.0 with a 1000 replicate bootstrap based on the neighbor joining, maximum likelihood, maximum parsimony method.  Results: A concatenated dataset containing a total of 14 sequences from Cantharellus, Craterellus (Cantharellaceae, Canthraellales) and Hydnum (Hydnaceae, Cantharellales) were constructed. For the specimen XC02, the phylogenies based on the first, second, and third datasets (nrLSU, nrSSU, and nrLSU-nrSSU) and the morphological analysis, reported in our previous study, strongly confirmed the identity of XC02 as Cantharellus minor.Conclusion: The combination between the morphological analysis and phylogenetic analysis is confirmed as the best approach for the identification of Cantharellus and other mushroom species that we collected in the Central Highlands, Vietnam.Keywords: nrLSU; Cantharellus, Cantharellus minor; nrSSU; nrLSU; phylogeny analysis; Vietna

Slip Resistance Test Apparatus of Synthetic Rubber Trackpad on Photovoltaic Surface

The increasing development of the solar energy industry in many countries has led to a rising frequency of human and robot presence in this area. To ensure occupational safety, various protective equipment, including rubber material, is commonly used for slip resistance while moving on the surface of solar PV panels. Therefore, the slip resistance test apparatus is built for testing the slip resistance between the synthetic rubber trackpad and the photovoltaic panel (PV) surface. Synthetic rubber is a man-made material, so it is difficult to control the parameters of its mechanical and chemical properties absolutely. Variations in wet/dry working conditions or Shore hardness are factors that make slip computation more challenging. Therefore, an apparatus with the principle of converting the reciprocating motion of the screw and the casters into the rotation of the hinge is introduced to adjust the tilt angle of the upper surface, detect and evaluate the slippage of the rubber trackpad by sensors. Some parameters related to accuracy such as vibration and theoretical-empirical assessment, are also mentioned. In addition to designing a reliable apparatus, the article also succeeded in providing a safety standard for synthetic rubber with Shore A30-A40 when moving on PV surfaces.Comment: 4 pages, 10 figures, The 20th International Conference on Ubiquitous Robots (UR 2023

A case study on trade in threatened Tiger Geckos (Goniurosaurus) in Vietnam including updated information on the abundance of the Endangered G. catbaensis

Tiger geckos of the genus Goniurosaurus are considered as a susceptible reptile group, due to their restricted distribution ranges, specialisation to specific microhabitats and generally low population densities. While still new species have been discovered recently, Goniurosaurus species are threatened by extinction through habitat loss and collection for the pet trade. Of the 19 described species, for only eight species, the conservation status has been assessed within the IUCN Red List between 2016 and 2018 and all have been classified in the threat categories VU (Vulnerable), EN (Endangered) and CR (Critically Endangered). Goniurosaurus spp. are popular in the international pet market at least since the 1990s and several species experienced local extirpations as a consequence of massive over-collection in the past. However, tiger geckos have not been paid much attention for conservation, amongst others, due to the lack of comprehensive knowledge on their conservation status and biology. This study provides an overview of international trade in Goniurosaurus based on available data from 1999 to 2018 in the U.S. as well as data from online surveys and interviews in Europe and Vietnam, with the main focus on species native to Vietnam. All five tiger gecko species known from Vietnam were found in the local trade as wild captures for the national and international market and / or in the U.S. and Europe for relatively higher prices. We found that entire trade chains are very long (including several transfers and dealers involved) and that keeping and transport happen under poor conditions. We herein provide updated information on the abundance of the Endangered Cat Ba Tiger Gecko, which was recently shown to not only occur at its type locality, Cat Ba Island, Hai Phong City, North Vietnam, but also to inhabit small offshore islands in the Ha Long Bay, Quang Ninh Province. While the wild effective population was found to be relatively stable on four islands in Ha Long Bay, consisting of about 124 and 129 individuals in July 2017 and April 2018, respectively, the abundance of other sub-populations, impacted by anthropogenic pressures were found to be very low (2–10 individuals). Based on our findings, we propose stringent conservation measures to more efficiently protect wild tiger gecko populations, such as the inclusion in the Governmental Decree in Vietnam, the assessment of remaining species in the IUCN Red List of Threatened Species and the inclusion in the Appendices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

Hidden in the jungle of Vietnam: a new species of Quasipaa (Amphibia, Anura, Dicroglossidae) from Ngoc Linh Mountain

A new species of Quasipaa is described from Ngoc Linh Mountain of the Kon Tum Massif in central Vietnam. The new species is morphologically distinguishable from its congeners on the basis of a combination of the following diagnostic characters: SVL 79.6–84.3 mm in males and 64.6–69.9 mm in females; head broader than long; vomerine teeth present; external vocal sacs absent; tympanum slightly visible; dorsum with lines of thick ridges and small round tubercles; flanks covered by oval and round tubercles; supratympanic fold present; dorsolateral fold absent; ventrolateral sides, ventral surface of arms, and all fingers with spines in males; the absence of spines on chest and belly in males; toes fully webbed to distal portion of terminal phalanx; in life, dorsum dark brown, chest and belly immaculate white. Phylogenetic analyses found that the genetic divergence of the new species and its congeners ranged from 4.2–5.1% (compared with Quasipaa boulengeri) to 7.6–8.1% (compared with Q. shini) in the 16S gene