2,342 research outputs found

    Autonomous power expert system

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    The Autonomous Power Expert (APEX) system was designed to monitor and diagnose fault conditions that occur within the Space Station Freedom Electrical Power System (SSF/EPS) Testbed. APEX is designed to interface with SSF/EPS testbed power management controllers to provide enhanced autonomous operation and control capability. The APEX architecture consists of three components: (1) a rule-based expert system, (2) a testbed data acquisition interface, and (3) a power scheduler interface. Fault detection, fault isolation, justification of probable causes, recommended actions, and incipient fault analysis are the main functions of the expert system component. The data acquisition component requests and receives pertinent parametric values from the EPS testbed and asserts the values into a knowledge base. Power load profile information is obtained from a remote scheduler through the power scheduler interface component. The current APEX design and development work is discussed. Operation and use of APEX by way of the user interface screens is also covered

    Experimental study of the long-term shortening of reinforced concrete columns under maintaining concentric axial load

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    This paper presents the results of an experimental study to measure the shortening of reinforced concrete (RC) columns under long-term maintaining concentric axial load. Long-term axial deformation due to shrinkage and creep of the concrete were recorded beside deformation due to mechanical load. Eight RC cylinder - columns (content of reinforcement 1.5% and 2%) with diameter of 150 mm and height of 600 mm were tested during the period of 600 days to determine their shortening. The experimental results showed that the long-term deformation of RC columns occurs primarily during the first year of loading. The deformation creep of concrete is much greater than the shrinkage deformation. The reinforcement content has a significant effect on the long-term deformation of concrete columns

    Experimental study of the long-term shortening of reinforced concrete columns under maintaining concentric axial load

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    This paper presents the results of an experimental study to measure the shortening of reinforced concrete (RC) columns under long-term maintaining concentric axial load. Long-term axial deformation due to shrinkage and creep of the concrete were recorded beside deformation due to mechanical load. Eight RC cylinder - columns (content of reinforcement 1.5% and 2%) with diameter of 150 mm and height of 600 mm were tested during the period of 600 days to determine their shortening. The experimental results showed that the long-term deformation of RC columns occurs primarily during the first year of loading. The deformation creep of concrete is much greater than the shrinkage deformation. The reinforcement content has a significant effect on the long-term deformation of concrete columns

    Factors influencing the occurrence of labour accidents in Vietnamese residential construction projects

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    There was a sharp increase in the annual injury rate and the annual death rate per 100,000 employees in the Vietnam construction industry (VCI) from 2000 to 2006. This study aimed to identify and analyze factors affecting the occurrence of labour accidents (OLA) in residential construction projects. A survey questionnaire was used to collect data from construction practitioners. The results show that labour accidents in the VCI resulted from factors related to unqualified construction resources, unsafe human behaviour and poor management. The results can be used to gain insight into the OLA in order to deal with high labour accident rate and to develop safety programs in Vietnam as well as in other developing countries

    Pedagogy undergraduates’ perception on twenty-first century skills

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    Teachers head up their students to the bright future, their role is indispensable, especially in the 21st century, which expects them to be energetic and flexible to apply knowledge to the daily life and carrier task. Examining the perception on 21st century skills teaching of pedagogy teacher-to-be undergraduates - plays a vital role in identifying deficits in teachers’ professional development; as well as organizing training programs to enhance their knowledge and skills. To the best of our knowledge, no study to date has examined pedagogy undergraduates’ perception in Vietnam. This study aimed at examining Vietnamese undergraduates' perception on teaching the 21st century skills. Our crosssectional study used the 21st Century Skills Teaching Scale. Descriptive analysis and ANOVA were performed in this research. The results showed that: (1) Vietnamese pedagogy students had a high level of perception on teaching the 21st century skills; (2) there was no gender difference in their perception; and (3) there was no significant difference in their perception regard to their school years and (4) there was significant difference between those having joined soft skill courses at their university and those having not joined anyone

    Antioxidant and Hepatoprotective Effects of Procyanidins fromWild Grape (Vitis amurensis) Seeds in Ethanol-Induced Cells and Rats

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    In the present study, we characterized the antioxidant and hepatoprotective mechanisms underlying of wild grape seed procyanidins (WGP) against oxidative stress damage in ethanol-treated HepG2 cell and Sprague-Dawley (SD)-rat models. In HepG2 cells, WGP not only diminished the ethanol (EtOH, 100 mM)-induced reactive oxygen species (ROS) formation and cytochrome P450 2E1 (CYP2E1) expression, but also renovated both the activity and expression of antioxidant enzymes including catalase, superoxide dismutase, and glutathione peroxidase. Additionally, to investigate the hepatoprotective effect of WGP, rats were orally administered 10 or 50 mg/kg WGP once daily for seven days prior to the single oral administration of EtOH (6 g/kg). The results show that WGP administration decreased the EtOH-induced augment of the levels of serum aspartate transaminase and alanine transaminase as well as serum alcohol and acetaldehyde. WGP treatment upregulated the activities and protein levels of hepatic alcohol dehydrogenase, aldehyde dehydrogenase, and antioxidant enzymes but downregulated the protein expression level of liver CYP2E1 in EtOH-treated rats. Moreover, the decreased phosphorylation levels of mitogen activated protein kinases (MAPKs) by ethanol were induced in both HepG2 cell and rat models. Overall, pretreatment of WGP displayed the protective activity against EtOH-mediated toxicity through the regulation of antioxidant enzymes and alcohol metabolism systems via MAPKs pathways

    Efficient and adaptive incentive selection for crowdsourcing contests

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    The success of crowdsourcing projects relies critically on motivating a crowd to contribute. One particularly effective method for incentivising participants to perform tasks is to run contests where participants compete against each other for rewards. However, there are numerous ways to implement such contests in specific projects, that vary in how performance is evaluated, how participants are rewarded, and the sizes of the prizes. Also, the best way to implement contests in a particular project is still an open challenge, as the effectiveness of each contest implementation (henceforth, incentive) is unknown in advance. Hence, in a crowdsourcing project, a practical approach to maximise the overall utility of the requester (which can be measured by the total number of completed tasks or the quality of the task submissions) is to choose a set of incentives suggested by previous studies from the literature or from the requester’s experience. Then, an effective mechanism can be applied to automatically select appropriate incentives from this set over different time intervals so as to maximise the cumulative utility within a given financial budget and a time limit. To this end, we present a novel approach to this incentive selection problem. Specifically, we formalise it as an online decision making problem, where each action corresponds to offering a specific incentive. After that, we detail and evaluate a novel algorithm, HAIS, to solve the incentive selection problem efficiently and adaptively. In theory, in the case that all the estimates in HAIS (except the estimates of the effectiveness of each incentive) are correct, we show that the algorithm achieves the regret bound o

    BIẾN ĐỘNG CỦA TRƯỜNG NHIỆT ĐỘ VÀ MỐI QUAN HỆ CỦA NÓ VỚI ENSO TRONG VÙNG BIỂN NINH THUẬN - BÌNH THUẬN

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    In this paper, our aim was to examine the role of ENSO in the recent climate variations. Analyzed results on temporal variability of thermal fields in period of 38 years (Jan. 1979-Aug. 2016) showed that Ninh Thuan - Binh Thuan waters were subjected to the significant impact of the ENSO phases (warming and cooling) as well as other processes related to seasonal, inter-seasonal, yearly and mutlti-yearly variations such as in the periods 1986-1989, 1996-2000 and 2009-2011. In order to clarify above issues, authors carried out the analysis of the temporal -spatial changes of temperature fields (include air temperature and sea surface temperature) in Ninh Thuan - Binh Thuan region. The temperature data were exploited from The National Centers for Environmental Prediction (NCEP) and Climate Forecast System Reanalysis (CFSR) in the form of hourly time-series products with spatial resolution of 0.3o (1979-2010) and 0.20o (2011-8/2016). The results showed that 2016 was quite similar to 1998 and 2010 when the coral bleaching occurred in the study area.Các kết quả phân tích trường nhiệt độ trong 38 năm (1/1979 - 8/2016) đã cho thấy vùng biển Ninh Thuận - Bình Thuận chịu sự tác động không nhỏ của các pha ENSO (ấm, lạnh) mà còn có liên quan đến các quá trình khác có chu kỳ mùa, liên mùa, năm, nhiều năm thể hiện tại các giai đoạn 1986-1989; 1996-2000 và 2009-2011. Để góp phần làm sáng tỏ vấn đề trên, chúng tôi đã tiến hành phân tích sự thay đổi nền nhiệt độ của nhiệt độ không khí, nhiệt độ nước bề mặt biển. Các số liệu nhiệt độ sử dụng trong nghiên cứu này được khai thác từ Hệ thống Dự đoán Khí hậu Phân tích lại (CFSR) theo bước thời gian 1 giờ với độ phân giải ngang 0,3° (1979-2010) và 0,2o (2011-8/2016) của Trung tâm Dự báo Môi trường Quốc gia Hoa Kỳ (NCEP). Kết quả phân tích cho thấy năm 2016 có nét khá tương đồng với năm 1998 và 2010, các năm được phát hiện đã xảy ra hiện tượng tẩy trắng san hô tại khu vực nghiên cứu
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