163 research outputs found
A Survey of Route Recommendations: Methods, Applications, and Opportunities
Nowadays, with advanced information technologies deployed citywide, large
data volumes and powerful computational resources are intelligentizing modern
city development. As an important part of intelligent transportation, route
recommendation and its applications are widely used, directly influencing
citizens` travel habits. Developing smart and efficient travel routes based on
big data (possibly multi-modal) has become a central challenge in route
recommendation research. Our survey offers a comprehensive review of route
recommendation work based on urban computing. It is organized by the following
three parts: 1) Methodology-wise. We categorize a large volume of traditional
machine learning and modern deep learning methods. Also, we discuss their
historical relations and reveal the edge-cutting progress. 2)
Application\-wise. We present numerous novel applications related to route
commendation within urban computing scenarios. 3) We discuss current problems
and challenges and envision several promising research directions. We believe
that this survey can help relevant researchers quickly familiarize themselves
with the current state of route recommendation research and then direct them to
future research trends.Comment: 24 pages, 13 figure
The Research of the Impact of Unconventional Emergencies on the Yield of Stock and Bond Markets
Unconventional emergencies will have an impact on financial markets. Studying on unconventional emergenciesâ impact on the financial markets is benefit to improve investorsâ risk awareness, and avoid the risks of unconventional emergencies. This paper uses ARIMA model to study the impact of Wenchuan earthquake on the stock market and bond market return. The results show that, because of investorsâ âflight-to-qualityâ behavior, Wenchuan earthquake had a negative impact on China's stock market, while had a positive impact on the bond market.Key words: Unconventional emergencies; stock market; bond market; ARIMA mode
The Method of Oilfield Development Risk Forecasting and Early Warning Using Revised Bayesian Network
Oilfield development aiming at crude oil production is an extremely complex process, which involves many uncertain risk factors affecting oil output. Thus, risk prediction and early warning about oilfield development may insure operating and managing oilfields efficiently to meet the oil production plan of the country and sustainable development of oilfields. However, scholars and practitioners in the all world are seldom concerned with the risk problem of oilfield block development. The early warning index system of blocks development which includes the monitoring index and planning index was refined and formulated on the basis of researching and analyzing the theory of risk forecasting and early warning as well as the oilfield development. Based on the indexes of warning situation predicted by neural network, the method dividing the interval of warning degrees was presented by â3Ïâ rule; and a new method about forecasting and early warning of risk was proposed by introducing neural network to Bayesian networks. Case study shows that the results obtained in this paper are right and helpful to the management of oilfield development risk
Review of the high bedâlow ditch system as an alternative to lowland paddy in tropical and subtropical Asia
Many forms of traditional raised bed systems could be found around the world. Several of them have been identified as Globally Important Agricultural Heritage Systems (GIAHS) sites by Food and Agriculture Organization of the United Nations. Unlike traditional raised bed systems with similar structures in the Americas, the high bedâlow ditch (HBLD) system in tropical and subtropical Asia, which is originated and developed from rice production, has been playing an important role in enhancing food security and maintaining farmer livelihood for centuries. Moreover, products provided by HBLD system are not only important for the livelihood of the local farmers, but also important for people living in the nearby towns and cities especially for vegetable and fruit supply. In this system, the ditches or sunken beds can be used to lower the groundwater table, retain nutrients and soil particles washed from the bed, grow rice or aquatic vegetables, and raise fish or shrimp. The HBLD system can also help to reduce salinity in coastal lowlands due to the presence of ditches. The raised beds can be used to grow various upland crops. Compared with rice monocropping, the adoption of HBLD system significantly improves the cropping intensity, productivity, employment, and income of farmers. Famersâ long-term practices fully demonstrate that this system is a type of sustainable agriculture with strong adaptability to the changes of natural environment. However, it should also be noted that the large-scale development of HBLD systems is not simply dependent on natural conditions, but is also determined by specific socioeconomic factors, such as good transportation facilities, a well market system, and a sufficient supply of labor. As a model of equilibrium between food production and high levels of biodiversity maintenance, the HBLD system is an important agricultural heritage system with global significance, and it should be well preserved and utilized in new ways to realize its important multiple functions under conditions of rapid urbanization in lowland and coastal regions
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Evaluating impacts of fish stock enhancement and biodiversity conservation actions on the livelihoods of smallâscale fishers on the Beijiang River, China
Inappropriate development and overexploitation have seriously degraded aquatic resources in China. Stakeholders identified three fish stock enhancement and biodiversity conservation scenarios for the Beijiang River: S1, increased fish restocking; S2, no fishing season and habitat conservation; and S3, strict pollution control. Potential impacts of these actions on the livelihoods of fishers were evaluated using applied economic modeling. Baseline costs and benefits came from logbooks from 30 fishers and a survey of 90 households in three villages. The financial net benefit for a household was US1651 and US1835 annually. Pollution control would benefit other resource users and is a prerequisite for ecological restoration
The parallax and 3D kinematics of water masers in the massive star-forming region G034.43+0.24
We report a trigonometric parallax measurement of 22 GHz water masers in the
massive star-forming region G034.43+0.24 as part of the Bar and Spiral
Structure Legacy (BeSSeL) Survey using the Very Long Baseline Array. The
parallax is 0.33050.018 mas, corresponding to a distance of
kpc. This locates G034.43+0.24 near the inner edge of
the Sagittarius spiral arm and at one end of a linear distribution of massive
young stars which cross nearly the full width of the arm. The measured
3-dimensional motion of G034.43+0.24 indicates a near-circular Galactic orbit.
The water masers display arc-like distributions, possibly bow shocks,
associated with winds from one or more massive young stars
Priming of jasmonate-mediated antiherbivore defense responses in rice by silicon
Although the function of silicon (Si) in plant physiology has long been debated, its beneficial effects on plant resistance against abiotic and biotic stresses, including insect herbivory, have been well documented. In addition, the jasmonate (JA) signaling pathway plays a crucial role in mediating antiherbivore defense responses in plants. However, potential interactions between JA and Si in response to insect attack have not been examined directly. To explore the role JA may play in Si-enhanced resistance, we silenced the expression of allene oxide synthase (OsAOS; active in JA biosynthesis) and CORONATINE INSENSITIVE1 (OsCOI1; active in JA perception) genes in transgenic rice plants via RNAi and examined resulting changes in Si accumulation and defense responses against caterpillar Cnaphalocrocis medinalis (rice leaffolder, LF) infestation. Si pretreatment increased rice resistance against LF larvae in wild-type plants but not in OsAOS and OsCOI1 RNAi lines. Upon LF attack, wild-type plants subjected to Si pretreatment exhibited enhanced defense responses relative to untreated controls, including higher levels of JA accumulation; increased levels of transcripts encoding defense marker genes; and elevated activities of peroxidase, polyphenol oxidase, and trypsin protease inhibitor. Additionally, reduced Si deposition and Si cell expansion were observed in leaves of OsAOS and OsCOI1 RNAi plants in comparison with wild-type plants, and reduced steady-state transcript levels of the Si transporters OsLsi1, OsLsi2, and OsLsi6 were observed in Si-pretreated plants after LF attack. These results suggest a strong interaction between Si and JA in defense against insect herbivores involving priming of JA-mediated defense responses by Si and the promotion of Si accumulation by JA
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