Tri-axis convective accelerometer with closed-loop heat source

In this paper, we report the details and findings of a study on tri-axis convective accelerometer, which is designed with the closed-loop type heat source and thermal sensing hotwire elements. The closed-loopheat source enhances the convective flow to the central part where a hotwire is placed to measure the vertical component of acceleration. The simulation was conducted using numerical analysis, and the devicewas prototyped by additive manufacturing. The device, functioning as a tilt sensor and an accelerometer,was tested up to acceleration of 20 g. The experiments were successfully conducted and the experimental results agreed reasonably with those obtained by numerical analysis. The results demonstrated that the closed-loop heat source could reduce the cross effect between the acceleration components. The scalefactor and cross-sensitivity had the values of 0.26 micro�V/g and 1.2%, respectively. The cross-sensitivity andthe effects of heating power were also investigated in this study

A Solution of Plane Stress Problem Subjected to Horizontal Shear Force by Using Polynomial Airy Stress Function

Many structural analysis problems in civil engineering and mechanical engineering can be treated as plane stress and plane strain problems introduced in the theory of elasticity. One of the popular analytical methods to tackle plane analysis is to determine Airy stress function. In general, the Airy stress function depends on the analyzed domain and the applied loads; however, the number of problems that can be solved by employing this method is limited because of the formidable challenges of guessing trial function. In many cases, the trial Airy stress functions are selected based on the results of a simple beam model or experimental results. This paper introduces a solution of the plane stress subjected to horizontal shear forces by using a polynomial Airy stress function, in which the trail function is predicted from the results of the elementary beam theory of an equivalent model. The numerical investigation on stress distributions was presented, and it showed that although the internal shear force acting on cross-sections have not appeared, shear stress still appeared, and the shear stress diagram had both negative and positive areas

A Solution of Plane Stress Problem Subjected to Horizontal Shear Force by Using Polynomial Airy Stress Function

Many structural analysis problems in civil engineering and mechanical engineering can be treated as plane stress and plane strain problems introduced in the theory of elasticity. One of the popular analytical methods to tackle plane analysis is to determine Airy stress function. In general, the Airy stress function depends on the analyzed domain and the applied loads; however, the number of problems that can be solved by employing this method is limited because of the formidable challenges of guessing trial function. In many cases, the trial Airy stress functions are selected based on the results of a simple beam model or experimental results. This paper introduces a solution of the plane stress subjected to horizontal shear forces by using a polynomial Airy stress function, in which the trail function is predicted from the results of the elementary beam theory of an equivalent model. The numerical investigation on stress distributions was presented, and it showed that although the internal shear force acting on cross-sections have not appeared, shear stress still appeared, and the shear stress diagram had both negative and positive areas

A Review of Occupational Stress among Certain Jobs in Vietnam

Background: Stress in the modern workplace is globally considered a risk factor for workers’ health and safety. However, a review of the prevalence and associated factors of occupational stress in developing countries like Vietnam was largely lacking. This review aimed to describe the situation of occupational stress among certain jobs from studies carried out in Vietnam. Methods: The review was implemented by using key words to search on online and offline, international and national database. After going through 2 stages of selections, total 25 eligible articles were chosen and used for this review. Results: The results showed the prevalence of occupational stress was varied and ranged from 6.4% to 90.4%. The study population focused on health workers, factory workers, students, academic staff and officers. The prevalence of each occupation ranged from 6.4% to 90.4% in health workers; 20.7% to 89.6% in factory workers; and 22.8% to 68.3% in students. Conclusions: In conclusion, the prevalence of occupational stress was very varied between and within each occupation. Therefore, a new way to develop in enhancing the occupational stress data, particularly in developing countries, is urgently needed

Identify and predict incorrect prices by Machine Learning Model

Electronic commerce (e-commerce) brings huge advantages to businesses for selling products through multiple online shops. However, companies have difficulties in supervising the prices of products set by different retail shops on e-commerce platforms. Addressing these difficulties, we suggest a method to identify and predict products that sell at incorrect prices using a machine learning model combined price analysis. The study uses four machine learning models: K-nearest Neighbor (KNN), Random Forest (RF), Support Vector Machine (SVM), and Multinomial Naive Bayes (MNB) and two text-based information extraction methods: BoW and TF-IDF to find to the best method. The research results show that the RF model and text-based information extraction method by the BoW provide more average accuracy than other specific models, when experimenting on the filter dataset the average accuracy after 10 runs are RF: 98.06%, SVM: 83.92%, MNB: 92.21%, KNN: 94.06%. Experimental results on the product dataset have an accuracy of RF: 83.02%, SVM: 55%, MNB: 79.33%, KNN: 79.36%

Fuzzy gain scheduling control apply to an RC Hovercraft

The Fuzzy Gain Scheduling (FGS) methodology for tuning the Proportional – Integral – Derivative (PID) traditional controller parameters by scheduling controlled gains in different phases, is a simple and effective application both in industries and real-time complex models while assuring the high achievements over pass decades, is proposed in this article. The Fuzzy logic rules of the triangular membership functions are exploited on-line to verify the Gain Scheduling of the Proportional – Integral – Derivative controller gains in different stages because it can minimize the tracking control error and utilize the Integral of Time Absolute Error (ITAE) minima criterion of the controller design process. For that reason, the controller design could tune the system model in the whole operation time to display the efficiency in tracking error. It is then implemented in a novel Remote Controlled (RC) Hovercraft motion models to demonstrate better control performance in comparison with the PID conventional controller

DARK SOIL PITS AND GRAVES IN VOLCANIC CAVE C6.1, KRONG NO, DAK NONG PROVINCE: DOCUMENTATION AND DISCUSSION

Dark soil pits and graves are critical documents discovered in volcanic cave C6.1. As a result of the investigation and excavation of cave C6.1 conducted in 2017, 2018, and 2019, we have discovered vestiges of nine dark soil pits and seven relatively intact graves, together with teeth and other human remains scattered in the cultural layer. This is an important source of information on the racial composition of the prehistoric inhabitants of the Central Highlands during the Neolithic period, as well as the paleoenvironment, environmental adaptations, and flora and fauna that prehistoric inhabitants exploited for their livelihoods. This article introduces documents and reconstructs the socioeconomic picture of the prehistoric inhabitants of cave C6.1. It also contributes scientific documents for the general conservation and promotion of heritage to develop sustainable cultural tourism in Dak Nong Province

BIODIVERSITY AND DISTRIBUTION PATTERNS OF FREE-LIVING NEMATODES COMMUNITIES IN BALAI RIVER, BENTRE PROVINCE

Nematodes communities in Ba Lai river, Ben Tre province were investigated in September of 2015 (eight stations from estuary to upstream). The results showed that the nematodes communities have characterized by high density and biodiversity, providing useful information of nematodes assemblages in freshwater habitas, in particular inland river. Also the results indicated that the distribution of nematodes communities in Ba Lai river was strongly discriminated between in and outside of dam with two groups. The Ba Lai dam may be reasons for cause  the nematodes distribution discontinuity. Present study is a pioneering attempt to record the impact of the dam on benthic-invertebrate in Vietnam

Review and Evaluation of Agricultural Policies in Years 2015-2017

This journal article describes main results of the OECD Annual Report published in 2018, titled “Review and evaluation of agricultural policy in 2017” for 51 selected countries in the world, including Vietnam. The report is closely prepared by MARD and OECD experts. The journal article emphasizes more on Vietnam by updating and adjusting data, information and policies in 2017 and 2018. The description presents the changing trend of agricultural policies applied in the world, considering whether this trend is in the direction of achieving sustainable productivity growth, environmental protection, and adaptation to climate change. On average in the last 20 years, trend of world policies has been better but far to catch above purposes. The development of international trade has made the commodity movement more freely and price gaps narrowed between countries and regions. This trend made agricultural markets developed more toward reflecting the scarcity of good and services. Average level of total agricultural supports has been reducing. Consequently, the world price indices and the total support have been converted between countries and commodities. However, the total agricultural support reduction is mainly in developed countries like OECD countries. Emerging and developing countries have increased their agricultural supports. Relative to GDP, the level of the total agriculture support in Vietnam has been reducing.Inside the total agricultural support, producer supports accounted 78% while general service support accounted only for 14%. Inside the producer support, market price support accounted for more than 50% in many countries. Payments based on outputs and inputs also accounted more than 50% in many countries. In Vietnam, the producer support is very small, negative level in 2015 and 2016 and became positive in 2017 and 2018. The agricultural producer support in 2017 is about 900 million USD. In the overall service support, many countries mainly invest in infrastructure construction, for example in Japan and Vietnam over 70%, while investments in other items are too small, for example that in Vietnam is only about 16%.In conclusion, OECD suggests that market price support should be reduced and finally eliminated. Similarly, output and input payments should be reduced and eliminated. Future policies should focus on general support service that helps producers to achieve sustainable productivity growth in the context of a changing and uncertain climate. OECD especially emphasizes on appropriate investments in research, together with efforts to ensure that the outputs of this research reach farmers. OECD also emphasizes on research that help producers to better manage risks including business risk, weather risk, and climate changes. Agricultural production and climate changes are strongly interacted. Future research should be the better co-operation between public and private sectors with the leading role of public sector. The future research should be co-operated more strongly between countries and regions because of the differences in histories, cultures, geology and climate