111 research outputs found

    GROUNDWATER TREATMENT TECHNOLOGIES FOR THE NATIONAL PROGRAM "CLEAN WATER AND ENVIRONMENTAL SANITARY" OF HOCHIMINH CITY AND SOUTHERN PROVINCES

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    Joint Research on Environmental Science and Technology for the Eart

    Two-Phase Defect Detection Using Clustering and Classification Methods

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    Autonomous fault management of network and distributed systems is a challenging research problem and attracts many research activities. Solving this problem heavily depends on expertise knowledge and supporting tools for monitoring and detecting defects automatically. Recent research activities have focused on machine learning techniques that scrutinize system output data for mining abnormal events and detecting defects. This paper proposes a two-phase defect detection for network and distributed systems using log messages clustering and classification. The approach takes advantage of K-means clustering method to obtain abnormal messages and random forest method to detect the relationship of the abnormal messages and the existing defects. Several experiments have evaluated the performance of this approach using the log message data of Hadoop Distributed File System (HDFS) and the bug report data of Bug Tracking System (BTS). Evaluation results have disclosed some remarks with lessons learned

    Experiment-based Comparative Analysis of Nonlinear Speed Control Methods for Induction Motors

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    Field-oriented control (FOC) for induction motors is widely used in industrial applications. By using a fast and accurate torque controller based on a stator current controller it is possible to flexibly implement advanced speed control methods to achieve proper performance both in transient and steady-state states. In this study, a deadbeat controller was used for the current loop. The nonlinear methods used for the outer loop controller were backstepping, flatness-based control, and exact feedback linearization with state derivative. The dynamic responses of these three controls were compared through various experimental results. The advantages and disadvantages of the different control structures were analyzed and evaluated in detail. Based on this evaluation, an appropriate scheme can be specified when deployed in practice

    Review and Evaluation of Agricultural Policies in Years 2015-2017

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    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

    Cost optimization of two-stage helical gearboxes with second stage double gear-sets

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    In practice, the cost of a gearbox plays a very important role in the trade. Therefore, reducing the cost of gearboxes is an important task not only when manufacturing the gearboxes but also when designing them. In order to reduce the cost of a gearbox, there are many solutions in which determining the optimal partial gear ratios of a gearbox is an effective measure. This is because it not only the size, the mass but also the cost of a gearbox depends greatly on the partial gear ratios. This work presents a method for calculating the cost function of two-stage helical gearboxes with second-stage double gear-sets based on the mass of the components that construct the gearbox. The cost objective function is minimized to achieve the optimal transmission ratios. Furthermore, screening experiments are carried out with nine important input parameters that have significant effects on the optimum transmission ratio of the second stage. These parameters are the total gearbox ratio, the coefficient of wheel face width of the first stage, coefficient of wheel face width of the second stage, the allowable contact stress of the first stage, the allowable contact stress of the second stage, the output torque, the cost of gearbox housing, the cost of gears, and the shaft cost. The experimental results of were analysed by using the Analysis of Variance (ANOVA) method with the help of Minitab 19 software. The results demonstrate that the effective weight of the input parameters and their interactions on the output response was investigated. Also, a regression model for computing the optimal transmission ratio of the second stage was proposed. This brings significance not only in the design process but also in manufacturing since the gearbox cost can decreas

    Liquid pumping and mixing by PZT synthetic jet

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    In this paper, a PZT synthetic jet that can function as both an efficient pumping and mixing device is developed. Compare with the conventional design where the practice of controlling the internal flow is undertaken by microvalves structure, this approach promotes the durability and allows the device to work with different liquids at high Reynold number without losing of backflow from the diffuser, therefore provides efficient mixing. The pumping performance is applicable for commercialized counterparts while the homogeneous medium was obtained at downstream in the experiments, which was further confirmed by simulation. Notably, the chaotic mixing feature of the device is also applicable for immiscible liquids with the micro-droplet formation result at the outlet

    SIP-MBA: A secure IoT platform with brokerless and micro-service architecture

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    The Internet of Things is one of the most interesting technology trends today. Devices in the IoT network are often geared towards mobility and compact in size, thus having a rather weak hardware configuration. There are many light weight protocols, tailor-made suitable for limited processing power and low energy consumption, of which MQTT is the typical one. The current MQTT protocol supports three types of quality-of-service (QoS) and the user has to trade-off the security of the packet transmission by transmission rate, bandwidth and energy consumption. The MQTT protocol, however, does not support packet storage mechanisms which means that when the receiver is interrupted, the packet cannot be retrieved. In this paper, we present a broker-less SIP-MBA Platform, designed for micro-service and using gRPC protocol to transmit and receive messages. This design optimizes the transmission rate, power consumption and transmission bandwidth, while still meeting reliability when communicating. Besides, we implement users and things management mechanisms with the aim of improving security issues. Finally, we present the test results by implementing a collect data service via gRPC protocol and comparing it with streaming data by using the MQTT protocol.Web of Science12759358

    IoHT-MBA: An Internet of Healthcare Things (IoHT) platform based on microservice and brokerless architecture

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    Internet of Thing (IoT), currently, is one of the technology trends that are most interested. IoT can be divided into five main areas including: Health-care, Environmental, Smart city, Commercial and Industrial. The IoHT-MBA Platform is considered the backbone of every IoT architecture, so the optimal design of the IoHT-MBA Platform is essential issue, which should be carefully considered in the different aspects. Although, IoT is applied in multiple domains, however, there are still three main features that are challenge to improve: i) data collection, ii) users, devices management, and iii) remote device control. Today's medical IoT systems, often too focused on the big data or access control aspects of participants, but not focused on collecting data accurately, quickly, and efficiently; power redundancy and system expansion. This is very important for the medical sector - which always prioritizes the availability of data for therapeutic purposes over other aspects. In this paper, we introduce the IoHT Platform for Healthcare environment which is designed by microservice and brokerless architecture, focusing strongly on the three aforementioned characteristics. In addition, our IoHT Platform considers the five other issues including (1) the limited processing capacity of the devices, (2) energy saving for the device, (3) speed and accurate of the data collection, (4) security mechanisms and (5) scalability of the system. Also, in order for the IoHT Platform to be suitable for the field of health monitoring, we also add realtime alerts for the medical team. In the evaluation section, moreover, we describe the evaluation to prove the effectiveness of the proposed IoHT Platform (i.e. the proof-of-concept) in the performance, non-error, and non affected by geographical distance. Finally, a complete code solution is publicized on the authors' GitHub repository to engage further reproducibility and improvement.Web of Science12760159
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