105 research outputs found
FMI Compliant Approach to Investigate the Impact of Communication to Islanded Microgrid Secondary Control
In multi-master islanded microgrids, the inverter controllers need to share
the signals and to coordinate, in either centralized or distributed way, in
order to operate properly and to assure a good functionality of the grid. The
central controller is used in centralized strategy. In distributed control,
Multi-agent system (MAS) is considered to be a suitable solution for
coordination of such system. However the latency and disturbance of the network
may disturb the communication from central controller to local controllers or
among agents or and negatively influence the grid operation. As a consequence,
communication aspects need to be properly addressed during the control design
and assessment. In this paper, we propose a holistic approach with
co-simulation using Functional Mockup Interface (FMI) standard to validate the
microgrid control system taking into account the communication network. A
use-case of islanded microgrid frequency secondary control with MAS under
consensus algorithm is implemented to demonstrate the impact of communication
and to illustrate the proposed holistic approach.Comment: Proceedings of the IEEE PES ISGT Asia 2017 conferenc
Pathways for the Development of Future Intelligent Distribution Grids
The next decade will bring several technical and organisational challenges to the electrical distribution grids, which are becoming an important pillar of the energy transition. Distribution system operators will play a crucial role and thus need to find innovative solutions that will prepare them for these changes. Allowing the variations in the size, organisation and technical characteristics of distribution grids, this paper presents the pathways for the distribution system operators developed within the scope of the UNITED-GRID project. These were developed in close cooperation with distribution grids and demonstration sites in the Netherlands, France and Sweden. Investment decision tools based on future scenarios and future-readiness assessment form the first step to steer the distribution system operators towards the necessary technical and digital innovations that increase the observability and controllability of the grid. Secondly, the guidelines present new types of business models that can be integrated into the operators’ portfolios. Thirdly, a workshop methodology is proposed to define the new internal requirements that make distribution system operators more agile to face the fast impacts of the energy transition. Case studies from the demonstration sites are used as examples in the paper
Firm-specific News and Anomalies
This study investigates the relation between idiosyncratic volatility and future returns around the firm-specific news announcements in the Korean stock market from July 1995 to June 2018. The excess returns of decile portfolios that are formed by sorting the stocks based on news and non-news idiosyncratic volatility measures. The Fama and French three-factor model is also examined to see whether systematic risk affects news and non-news idiosyncratic volatility profits. The pricing of our news and non-news idiosyncratic volatility are confirmed in the cross-sectional regression using the Fama and MacBeth method. Market beta, size, book to market, momentum, liquidity, and maximum return are controlled to determine robustness. Our empirical evidence suggests that the pricing of the non-news idiosyncratic volatility is more strongly negative compared to the news idiosyncratic volatility, which is contrary to the limited arbitrage explanation for the negative price of the idiosyncratic volatility. We find that the non-news idiosyncratic volatility has a robust negative relation to returns in non-January months. Macro-finance factors drive the conditioned on the missing risk factor hypothesis, the pricing of idiosyncratic volatility. This study contributes to a better understanding of the role of the conditional idiosyncratic volatility in asset pricing. As the Korean stocks provide a fresh sample, our non-U.S. investigation delivers a useful out-of-sample test on the pervasiveness of the non-news volatility effect across the emerging markets
ỨNG DỤNG TƢ LIỆU ẢNH VIỄN THÁM VÀ CÔNG NGHỆ GIS THÀNH LẬP BẢN ĐỒ NGUY CƠ CHÁY RỪNG TỈNH ĐẮK LẮK
Forest fire is one of the disasters causing threats to the forests and the ecosystem and socio-economic aspects throught out the world. Forest fire also leads to an increase in green house gases emisstions. Air pollution due to smoke causes prolonged effects on human health such as respiratory and cardiovascular problems. Knowledge of flammable materials and their potential fire behavior in different forest types is essential in forest fire management. Remote Sensing and GIS can play an important role in detecting burnt forest and developing the spatial models to predict potential forest for fire risk. This study demonstrates the effective use of remote sensing imagery and geographic information system for establishing the forest fire hazard map at scale of 1:100.000 for Daklak province. Landsat ETM image captured in 2011 and Weighted Overlay tool in ArcGIS software were used in this study. Eight parameters of forest types, daily average temperature during dry season, daily average precipitation in dry season, daily average wind speed, slope, terrain direction, distant between burned field to forest and distant from resident to forest were used as main inputs in GIS model. The study result shown that, the total fire area at low fire risk is 219,344 ha (accounting for 35.9% of total area of forest in Daklak province), medium fire risk is 130,207 ha (21.3%), high fire risk is 220,565 ha (36.1%) and very high fire risk is 41,488 ha (6.8%).ReferencesAmparo, A.B., Oscar, F.R., 2003. An intelligent system for forest fire risk prediction and fire fighting management in Galicia. Expert Systems with Applications 25(6), 545-554. Chuvieco, E., Congalton, R.G., 1989. Application of remote sensing and geographic information systems to forest fire hazard mapping. Remote Sensing of the Environment 29, 147-159. Dong, X.U., 2005. Forest fire risk zone mapping from satellite images and GIS for Baihe Forestry Bureau, Jilin, China. Journal of Forestry Research 16(3), 169-174. Gholamreza, J.G., Bahram, G., Osman, M.D., 2012. Forest fire risk zone mapping form Geographic Information System in Northern Forests of Iran (Case study, Golestan province). International Journal of Agriculture and Crop Science 4(12), 818-824. Phạm Ngọc Hưng, 2001. Thiên tai khô hạn cháy rừng và giải pháp phòng cháy chữa cháy rừng ở Việt Nam. Nxb. Nông nghiệp, Hà Nội, 224tr. Phạm Ngọc Hưng, 2004. Quản lý lửa rừng ở Việt Nam. Nxb. Nghệ An, 231tr. Jaiswal, R.K., Mukherjee, S., Raju, D.K., Saxena, R., 2002. Forest fire risk zone mapping from satellite imagery and GIS. International Journal of Applied Earth Observation and Geoinformation 4, 1-10. Lazaros, S.I, Anastaios, K.P., Panagiotis, D.L., 2002. A computer-system that classifies the prefectures of Greece in forest fire risk zones using fuzzy sets [J]. Forest Policy and Economics 4, 43-54. Mariel, A., Marielle, J., 1996. Wildland fire risk mapping using a geographic information system and including satellite data: Example of "Les Maures" forest, south east of France [J]. EARSeL Advances in Remote Sensing 4(4), 49-56. Shailesh Nayak, Sisi Zlatanova, 2008. Remote sensing and GIS technologies for monitoring and prediction of disasters. Springer-Verlag Environment Science and Engineering, 127pp. William, A.T., Ilan, V., Hans, S., 2000. Using forest fire hazard modeling in multiple use forest management planning [J]. Forest Ecology and Management 134(2), 163-176. Bộ Nông nghiệp và Phát triển nông thôn, 2004. Cẩm nang ngành lâm nghiệp - Chương "Phòng cháy và chữa cháy rừng". Chương trình hỗ trợ ngành lâm nghiệp và đối tác, 89tr. Chi cục Kiểm lâm Đắk Lắk, 2012. Báo cáo chuyên đề "Thực trạng cháy rừng, nguyên nhân và các giải pháp phòng cháy chữa cháy rừng". Tài liệu lưu trữ tại Viện Địa lý, 27tr. Forest fire is one of the disasters causing threats to the forests and the ecosystem and socio-economic aspects throught out the world. Forest fire also leads to an increase in green house gases emisstions. Air pollution due to smoke causes prolonged effects on human health such as respiratory and cardiovascular problems. Knowledge of flammable materials and their potential fire behavior in different forest types is essential in forest fire management. Remote Sensing and GIS can play an important role in detecting burnt forest and developing the spatial models to predict potential forest for fire risk. This study demonstrates the effective use of remote sensing imagery and geographic information system for establishing the forest fire hazard map at scale of 1:100.000 for Daklak province. Landsat ETM image captured in 2011 and Weighted Overlay tool in ArcGIS software were used in this study. Eight parameters of forest types, daily average temperature during dry season, daily average precipitation in dry season, daily average wind speed, slope, terrain direction, distant between burned field to forest and distant from resident to forest were used as main inputs in GIS model. The study result shown that, the total fire area at low fire risk is 219,344 ha (accounting for 35.9% of total area of forest in Daklak province), medium fire risk is 130,207 ha (21.3%), high fire risk is 220,565 ha (36.1%) and very high fire risk is 41,488 ha (6.8%)
Unexpected cases in field diagnosis of African swine fever virus in Vietnam: The needs consideration when performing molecular diagnostic tests
Background: The first confirmed case of African swine fever (ASF) in Vietnam was reported officially in February 2019. To date, ASF virus (ASFV) have been detected in 63/63 provinces in Vietnam. Currently, real-time polymerase chain reaction (PCR) is considered to be a powerful tool for viral detection in field samples, including ASFV. However, some recent reports have suggested that mismatches in primer and probe binding regions may directly affect real-time PCR qualification, leading a false-negative result.Aim: This study aims to further examine a conflicting result obtained from two OIE recommended methods, conventional PCR and real-time PCR, for ASFV detection.Methods: Two ASF suspected pigs from different provinces in the north of Vietnam were selected for this study based on clinical signs and postmortem lesions. The different results obtained by OIE-recommended conventional PCR and real-time PCR were further analyzed by the Sanger sequencing method and virus isolation in combination with hemadsorption (HAD) test using porcine alveolar macrophages cells.Results: The results showed that when the primer sequence matched perfectly with the sequences of field isolates, a mutation in probe binding region was found, indicating that a single mismatch in the probe binding site may cause a false-negative result by real-time PCR in detecting ASFV in clinical samples in Vietnam. An agreement between conventional PCR, using PPA1/PPA2 primers and two golden standard methods, virus isolation in combination with HAD assay, and sequencing method was observed in this study.Conclusion: A single mismatch in the probe binding site caused a failse-negative result by realtime PCR method in field diagnosis of ASFV. The needs consideration when selecting the appropriate molecular diagnostic methods is based on the current databases of ASFV sequences, particularly for epidemiological surveillance of ASF.
Keywords: African swine fever, PCR, Pigs, Real-time PCR, Vietna
SIP-MBA: A secure IoT platform with brokerless and micro-service architecture
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
- …