219 research outputs found

    Approximate declarative semantics for rule base anomalies

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    The article of record as published may be found at https://doi.org/10.1016/S0950-7051(99)00032-5Despite the fact that there has been a surge of publications in verification and validation of knowledge-based systems and expert systems in the past decade, there are still gaps in the study of verification and validation (V&V) of expert systems, not the least of which is the lack of appropriate semantics for expert system programming languages. Without a semantics, it is hard to formally define and analyze knowledge base anomalies such as inconsistency and redundancy, and it is hard to assess the effectiveness of V&V tools, methods and techniques that have been developed or proposed. In this paper, we develop an approximate declarative semantics for rule-based knowledge bases and provide a formal definition and analysis of knowledge base inconsistency, redundancy, circularity and incompleteness in terms of theories in the first order predicate logic. In the paper, we offer classifications of commonly found cases of inconsistency, redundancy, circularity and incompleteness. Finally, general guidelines on how to remedy knowledge base anomalies are given

    Exploration with Global Consistency Using Real-Time Re-integration and Active Loop Closure

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    Despite recent progress of robotic exploration, most methods assume that drift-free localization is available, which is problematic in reality and causes severe distortion of the reconstructed map. In this work, we present a systematic exploration mapping and planning framework that deals with drifted localization, allowing efficient and globally consistent reconstruction. A real-time re-integration-based mapping approach along with a frame pruning mechanism is proposed, which rectifies map distortion effectively when drifted localization is corrected upon detecting loop-closure. Besides, an exploration planning method considering historical viewpoints is presented to enable active loop closing, which promotes a higher opportunity to correct localization errors and further improves the mapping quality. We evaluate both the mapping and planning methods as well as the entire system comprehensively in simulation and real-world experiments, showing their effectiveness in practice. The implementation of the proposed method will be made open-source for the benefit of the robotics community

    Decentralized Visual-Inertial-UWB Fusion for Relative State Estimation of Aerial Swarm

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    The collaboration of unmanned aerial vehicles (UAVs) has become a popular research topic for its practicability in multiple scenarios. The collaboration of multiple UAVs, which is also known as aerial swarm is a highly complex system, which still lacks a state-of-art decentralized relative state estimation method. In this paper, we present a novel fully decentralized visual-inertial-UWB fusion framework for relative state estimation and demonstrate the practicability by performing extensive aerial swarm flight experiments. The comparison result with ground truth data from the motion capture system shows the centimeter-level precision which outperforms all the Ultra-WideBand (UWB) and even vision based method. The system is not limited by the field of view (FoV) of the camera or Global Positioning System (GPS), meanwhile on account of its estimation consistency, we believe that the proposed relative state estimation framework has the potential to be prevalently adopted by aerial swarm applications in different scenarios in multiple scales.Comment: Accepted ICRA 202

    Anti-inflammatory effects of Fritillaria ussuriensis maxim

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    Bulbs of Fritillaria ussuriensis Maxim., usually known as Bulbus Fritillariae ussuriensis, (BFU) has been used as antitussive, antiasthmatic and expectorant in traditional herbal medicine. In this study, the aqueous extract of BFU (BFUE) was evaluated for its anti-inflammatory activity. Meanwhile, the content of PGE2 and MDA in inflammatory exudates was measured to explore the anti-inflammatory mechanisms of BFUE. In order to identify the active components of BFU, the total alkaloids (TA), the total flavonoids (TF) and the total saponins (TS) were evaluated for their bioactivities. Results showed that BFUE inhibited carrageenin-induced paw edema, xylene-induced auricular edema and acetic acid-induced vascular permeation in a dose-dependent manner, and it revealed obvious inhibitory effects on the increase of PGE2 and MDA. TF showed the highest anti-inflammatory effects on auricular edema induced by xylene in mice, and TS at a dose of 400 and 200 mg/kg also showed good effects (P 2 and MDA levels, and TF and TS might be the active components for this activity.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Anti-inflammatory effects of Fritillaria ussuriensis maxim

    Get PDF
    Bulbs of Fritillaria ussuriensis Maxim., usually known as Bulbus Fritillariae ussuriensis, (BFU) has been used as antitussive, antiasthmatic and expectorant in traditional herbal medicine. In this study, the aqueous extract of BFU (BFUE) was evaluated for its anti-inflammatory activity. Meanwhile, the content of PGE2 and MDA in inflammatory exudates was measured to explore the anti-inflammatory mechanisms of BFUE. In order to identify the active components of BFU, the total alkaloids (TA), the total flavonoids (TF) and the total saponins (TS) were evaluated for their bioactivities. Results showed that BFUE inhibited carrageenin-induced paw edema, xylene-induced auricular edema and acetic acid-induced vascular permeation in a dose-dependent manner, and it revealed obvious inhibitory effects on the increase of PGE2 and MDA. TF showed the highest anti-inflammatory effects on auricular edema induced by xylene in mice, and TS at a dose of 400 and 200 mg/kg also showed good effects (P 2 and MDA levels, and TF and TS might be the active components for this activity.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Reliability evaluation of reservoir bank slopes with weak interlayers considering spatial variability

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    Reservoir bank slopes with weak interlayers are common in the Three Gorges Reservoir area. Their stabilities are affected by multi-coupled factors (e.g., reservoir water fluctuations, rainfall, and earthquakes in the reservoir area). Meanwhile, the differences in mechanical parameters of reservoir banks make it more difficult to determine the dynamic stability of bank slopes under complex mechanical environments. In this paper, the multiple disaster-causing factors and spatial variability of the landslide were comprehensively considered to study the long-term evolution trend of the bank slopes with weak interlayers. Specifically, the limit equilibrium method combined with the random field was performed to calculate the reliability. Furthermore, the long-term effects of dry-wet cycles on reservoir bank landslides and the sensitivity analysis of the statistical parameters of the random field were discussed. The results show that the earthquake action had the most significant impact on the failure probability of the landslide. The failure probability was more significantly affected by the vertical fluctuation range of the parameters and the coefficient of variation of the internal friction angle. The increase in failure probability under the action of dry-wet cycles was mainly caused by the reduction of the parameters of the weak interlayer. The reliability evaluation method of reservoir bank slopes can be applied to predict the long-term stability of the coastal banks

    Mapping the potential distribution of major tick species in China

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    Ticks are known as the vectors of various zoonotic diseases such as Lyme borreliosis and tick-borne encephalitis. Though their occurrences are increasingly reported in some parts of China, our understanding of the pattern and determinants of ticks’ potential distribution over the country remain limited. In this study, we took advantage of the recently compiled spatial dataset of distribution and diversity of ticks in China, analyzed the environmental determinants of ten frequently reported tick species and mapped the spatial distribution of these species over the country using the MaxEnt model. We found that presence of urban fabric, cropland, and forest in a place are key determents of tick occurrence, suggesting ticks were likely inhabited close to where people live. Besides, precipitation in the driest month was found to have a relatively high contribution in mapping tick distribution. The model projected that theses ticks could be widely distributed in the Northwest, Central North, Northeast, and South China. Our results added new evidence on the potential distribution of a variety of major tick species in China and pinpointed areas with a high potential risk of tick bites and tick-borne diseases for raising public health awareness and prevention response
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