scholarly journals Search strategy in a complex and dynamic environment: the MH370 case

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Stefan Ivić ◽  
Bojan Crnković ◽  
Hassan Arbabi ◽  
Sophie Loire ◽  
Patrick Clary ◽  
...  
Keyword(s):  
Success Rate ◽  
Search Algorithm ◽  
Dynamic Environment ◽  
Ocean Surface ◽  
Time Period ◽  
Detection Of Objects ◽  
Local Aggregation ◽  
Order Of Magnitude ◽  
Convergence Zones ◽  
Search Control

AbstractSearch and detection of objects on the ocean surface is a challenging task due to the complexity of the drift dynamics and lack of known optimal solutions for the path of the search agents. This challenge was highlighted by the unsuccessful search for Malaysian Flight 370 (MH370) which disappeared on March 8, 2014. In this paper, we propose an improvement of a search algorithm rooted in the ergodic theory of dynamical systems which can accommodate complex geometries and uncertainties of the drifting search areas on the ocean surface. We illustrate the effectiveness of this algorithm in a computational replication of the conducted search for MH370. We compare the algorithms using many realizations with random initial positions, and analyze the influence of the stochastic drift on the search success. In comparison to conventional search methods, the proposed algorithm leads to an order of magnitude improvement in success rate over the time period of the actual search operation. Simulations of the proposed search control also indicate that the initial success rate of finding debris increases in the event of delayed search commencement. This is due to the existence of convergence zones in the search area which leads to local aggregation of debris in those zones and hence reduction of the effective size of the area to be searched.

scholarly journals Gesture commands for controlling high-level UAV behavior

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
John Akagi ◽  
T. Devon Morris ◽  
Brady Moon ◽  
Xingguang Chen ◽  
Cameron K. Peterson
Keyword(s):  
Search Algorithm ◽  
Dynamic Environment ◽  
List Type ◽  
Hardware In The Loop ◽  
Monte Carlo Tree Search ◽  
Natural Interface ◽  
Constrained Environments ◽  
Novel Variant ◽  
High Level ◽  
Tree Search Algorithm

Abstract Directing groups of unmanned air vehicles (UAVs) is a task that typically requires the full attention of several operators. This can be prohibitive in situations where an operator must pay attention to their surroundings. In this paper we present a gesture device that assists operators in commanding UAVs in focus-constrained environments. The operator influences the UAVs’ behavior by using intuitive hand gesture movements. Gestures are captured using an accelerometer and gyroscope and then classified using a logistic regression model. Ten gestures were chosen to provide behaviors for a group of fixed-wing UAVs. These behaviors specified various searching, following, and tracking patterns that could be used in a dynamic environment. A novel variant of the Monte Carlo Tree Search algorithm was developed to autonomously plan the paths of the cooperating UAVs. These autonomy algorithms were executed when their corresponding gesture was recognized by the gesture device. The gesture device was trained to classify the ten gestures and accurately identified them 95% of the time. Each of the behaviors associated with the gestures was tested in hardware-in-the-loop simulations and the ability to dynamically switch between them was demonstrated. The results show that the system can be used as a natural interface to assist an operator in directing a fleet of UAVs. Article highlights A gesture device was created that enables operators to command a group of UAVs in focus-constrained environments. Each gesture triggers high-level commands that direct a UAV group to execute complex behaviors. Software simulations and hardware-in-the-loop testing shows the device is effective in directing UAV groups.

scholarly journals Analysis of Multisensory-Motor Integration in Olfactory Navigation of Silkmoth, Bombyx mori, using Virtual Reality System

2021 ◽  
Author(s):  
Mayu Yamada ◽  
Hirono Ohashi ◽  
Koh Hosoda ◽  
Daisuke Kurabayashi ◽  
Shunsuke Shigaki
Keyword(s):  
Virtual Reality ◽  
Success Rate ◽  
Wind Direction ◽  
Visual Information ◽  
Search Algorithm ◽  
Search Behavior ◽  
Direction Of Arrival ◽  
Behavioral Experiments ◽  
Direction Information ◽  
Multisensory Information

Most animals survive and thrive due to navigation behavior to reach their destinations. In order to navigate, it is important for animals to integrate information obtained from multisensory inputs and use that information to modulate their behavior. In this study, by using a virtual reality (VR) system for an insect, we investigated how an adult silkmoth integrates visual and wind direction information during female search behavior (olfactory behavior). According to the behavioral experiments using the VR system, the silkmoth had the highest navigation success rate when odor, vision, and wind information were correctly provided. However, we found that the success rate of the search signifcantly reduced if wind direction information was provided that was incorrect from the direction actually detected. This indicates that it is important to acquire not only odor information, but also wind direction information correctly. In other words, Behavior was modulated by the degree of co-incidence between the direction of arrival of the odor and the direction of arrival of the wind, and posture control (angular velocity control) was modulated by visual information. We mathematically modeled the modulation of behavior using multisensory information and evaluated it by simulation. As a result, the mathematical model not only succeeded in reproducing the actual female search behavior of the silkmoth, but can also improve search success relative to the conventional odor source search algorithm.

scholarly journals Impact of cytochrome P450 2C19 polymorphisms on the clinical efficacy and safety of voriconazole: an update systematic review and meta-analysis

2021 ◽  
Author(s):  
Ying Zhang ◽  
Xu Hao ◽  
Kelu Hou ◽  
Lei Hu ◽  
Jingyuan Shang ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Adverse Events ◽  
Success Rate ◽  
Clinical Efficacy ◽  
Search Algorithm ◽  
Efficacy And Safety ◽  
Increased Risk ◽  
Significant Difference ◽  
The Impact ◽  
Cyp2c19 Polymorphisms

Aims: To assess the impact of cytochrome P450 (CYP) 2C19 polymorphisms on the clinical efficacy and safety of voriconazole. Methods: We systematically searched PubMed, EMBASE, CENTRAL, ClinicalTrials.gov, and three Chinese databases from their inception to March 18, 2021 using a predefined search algorithm to identify relevant studies. Studies that reported voriconazole-treated patients and information on CYP2C19 polymorphisms were included. The efficacy outcome was success rate. The safety outcomes included overall adverse events, hepatotoxicity and neurotoxicity. Results: A total of 20 studies were included. Intermediate metabolizers (IMs) and Poor metabolizers (PMs) were associated with increased success rates compared with normal metabolizers (NMs) (risk ratio (RR): 1.18, 95% confidence interval (CI): 1.03~1.34, I2=0%, p=0.02; RR: 1.28, 95%CI: 1.06~1.54, I2=0%, p=0.01). PMs were at increased risk of overall adverse events in comparison with NMs and IMs (RR: 2.18, 95%CI: 1.35~3.53, I2=0%, p=0.001; RR: 1.80, 95% CI: 1.23~2.64, I2=0%, p=0.003). PMs demonstrated a trend towards an increased incidence of hepatotoxicity when compared with NMs (RR: 1.60, 95%CI: 0.94~2.74, I2=27%, p=0.08), although there was no statistically significant difference. In addition, there was no significant association between CYP2C19 polymorphisms and neurotoxicity. Conclusions: IMs and PMs were at a significant higher success rate in comparison with NMs. PMs were significantly associated with an increased incidence of all adverse events compared with NMs and IMs. Researches are expected to further confirm these findings. Additionally, the relationship between hepatotoxicity and CYP2C19 polymorphisms deservers clinical attention.

scholarly journals A Unifying View on Individual Bounds and Heuristic Inaccuracies in Bidirectional Search

2020 ◽  
Vol 34 (03) ◽  
pp. 2327-2334
Author(s):  
Vidal Alcázar ◽  
Pat Riddle ◽  
Mike Barley
Keyword(s):  
Lower Bound ◽  
Heuristic Search ◽  
Search Algorithm ◽  
Substantial Improvement ◽  
Full Potential ◽  
The Past ◽  
Heuristic Search Algorithms ◽  
Bidirectional Search ◽  
Order Of Magnitude ◽  
The Cost

In the past few years, new very successful bidirectional heuristic search algorithms have been proposed. Their key novelty is a lower bound on the cost of a solution that includes information from the g values in both directions. Kaindl and Kainz (1997) proposed measuring how inaccurate a heuristic is while expanding nodes in the opposite direction, and using this information to raise the f value of the evaluated nodes. However, this comes with a set of disadvantages and remains yet to be exploited to its full potential. Additionally, Sadhukhan (2013) presented BAE∗, a bidirectional best-first search algorithm based on the accumulated heuristic inaccuracy along a path. However, no complete comparison in regards to other bidirectional algorithms has yet been done, neither theoretical nor empirical. In this paper we define individual bounds within the lower-bound framework and show how both Kaindl and Kainz's and Sadhukhan's methods can be generalized thus creating new bounds. This overcomes previous shortcomings and allows newer algorithms to benefit from these techniques as well. Experimental results show a substantial improvement, up to an order of magnitude in the number of necessarily-expanded nodes compared to state-of-the-art near-optimal algorithms in common benchmarks.

scholarly journals Water balance of selected floodplain lake basins in the Middle Bug River valley

2014 ◽  
Vol 18 (4) ◽  
pp. 1457-1465 ◽  
Author(s):  
J. Dawidek ◽  
B. Ferencz
Keyword(s):  
Water Balance ◽  
River Valley ◽  
Floodplain Lake ◽  
Water Balance Components ◽  
River Waters ◽  
Main River ◽  
Time Period ◽  
Order Of Magnitude ◽  
Gains And Losses ◽  
Lake Basins

Abstract. This study is the first attempt in the literature on the subject of comparing water balance components for floodplain lake basins, depending on the type of a lake connection to the parent river. Research was carried out in the Bug River valley in 2007–2011 water years. Four types of connections were distinguished in the area under study. Simple water balance equation could only be used with regard to the lakes connected to the main river via the upstream crevasses. Detailed and individual water balance equations were developed with reference to the other types of lakes. Water gains and losses varied significantly in the lakes under study. Values of horizontal water balance components (inflow and outflow) of the floodplain lake in Wola Uhruska considerably prevailed over the vertical ones (precipitation and evaporation). Inflow of the Bug River waters was diverse during the time period under study and amounted from 600 000 to 2 200 000 m3 yr−1. Volumes of precipitation and evaporation were rather stable and amounted to approx. 30 000 m3 yr−1. The lowest disparity between horizontal and vertical water balance components was observed in the inter-levee lake. Both upstream inflow of rivers water and outflow from the lake (ranged from 0 in 2008 to 35 000 m3 yr−1 in 2009) were usually an order of magnitude higher than precipitation and evaporation from the lake surface (700–800 m3 yr−1). Study showed that the values and the proportion between aforementioned vertical and horizontal water balance elements were determined by the type of a lake connection to the Bug River. Storage volume showed no relationship to the type of connection, but resulted from individual features of the lakes (location within the valley, precipitation and evaporation volume, difference between water inflow and outflow).

scholarly journals Study on Composing Dense Formations in a Dynamic Environment of Multirotor UAVs by Distributed Control

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Shudao Zhou ◽  
Ao Shen ◽  
Min Wang ◽  
Shuling Peng ◽  
Zhanhua Liu
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Dynamic Model ◽  
Distributed Control ◽  
Distributed Algorithm ◽  
Search Algorithm ◽  
Dynamic Environment ◽  
Step Motion ◽  
Aerial Vehicles ◽  
Path Search ◽  
The Membership Function

In order to make multirotor unmanned aerial vehicles (UAV) compose a desired dense formation and improve the practicality of UAV formation, a distributed algorithm based on fuzzy logic was proposed. The airflow created by multirotor UAVs was analyzed according to the structure of the multirotor UAV and the characteristic equation of the fluid. This paper presented a dynamic model for the process of formation of and path search algorithm based on this model. The membership function in this model combines the factors of position, flow field, and movement. Integrating the dynamic model and its desired position in formations, each UAV evaluates the surrounding points and then selects the direction for step motion. Through simulation, this algorithm was improved by a by-step formation approach, and the effectiveness of this method in dense formation of multirotor UAVs was proved.

scholarly journals The isotopic composition of methane in the stratosphere: high-altitude balloon sample measurements

2011 ◽  
Vol 11 (24) ◽  
pp. 13287-13304 ◽  
Author(s):  
T. Röckmann ◽  
M. Brass ◽  
R. Borchers ◽  
A. Engel
Keyword(s):  
Isotopic Composition ◽  
Isotope Effects ◽  
Mixing Ratio ◽  
Kinetic Isotope ◽  
Time Period ◽  
Order Of Magnitude ◽  
Stratospheric Balloon ◽  
Single Balloon ◽  
Kinetic Fractionation ◽  
The Individual

Abstract. The isotopic composition of stratospheric methane has been determined on a large suite of air samples from stratospheric balloon flights covering subtropical to polar latitudes and a time period of 16 yr. 154 samples were analyzed for δ13C and 119 samples for δD, increasing the previously published dataset for balloon borne samples by an order of magnitude, and more than doubling the total available stratospheric data (including aircraft samples) published to date. The samples also cover a large range in mixing ratio from tropospheric values near 1800 ppb down to only 250 ppb, and the strong isotope fractionation processes accordingly increase the isotopic composition up to δ13C = −14‰ and δD = +190‰, the largest enrichments observed for atmospheric CH4 so far. When analyzing and comparing kinetic isotope effects (KIEs) derived from single balloon profiles, it is necessary to take into account the residence time in the stratosphere in combination with the observed mixing ratio and isotope trends in the troposphere, and the range of isotope values covered by the individual profile. The isotopic composition of CH4 in the stratosphere is affected by both chemical and dynamical processes. This severely hampers interpretation of the data in terms of the relative fractions of the three important sink mechanisms (reaction with OH, O(1D) and Cl). It is shown that a formal sink partitioning using the measured data severely underestimates the fraction removed by OH, which is likely due to the insensitivity of the measurements to the kinetic fractionation in the lower stratosphere. Full quantitative interpretation of the CH4 isotope data in terms of the three sink reactions requires a global model.

A Parallel Local Search Algorithm for Clustering Large Biological Networks

2017 ◽  
Vol 27 (03n04) ◽  
pp. 1750007
Author(s):  
Gaetano Coccimiglio ◽  
Salimur Choudhury
Keyword(s):  
Local Search ◽  
Biological Networks ◽  
Clustering Algorithm ◽  
Search Algorithm ◽  
Local Search Algorithm ◽  
Effective Technique ◽  
User Input ◽  
Time Period ◽  
Cluster Quality

Clustering is an effective technique that can be used to analyze and extract useful information from large biological networks. Popular clustering solutions often require user input for several algorithm options that can seem very arbitrary without experimentation. These algorithms can provide good results in a reasonable time period but they are not above improvements. We present a local search based clustering algorithm free of such required input that can be used to improve the cluster quality of a set of given clusters taken from any existing algorithm or clusters produced via any arbitrary assignment. We implement this local search using a modern GPU based approach to allow for efficient runtime. The proposed algorithm shows promising results for improving the quality of clusters. With already high quality input clusters we can achieve cluster rating improvements upto to 33%.

scholarly journals EFFECT OF SURFACTANTS ON UPTAKE OF GIBBERELLIN A3 BY SOUR CHERRY LEAVES

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1167d-1167
Author(s):  
Moritz Knoche ◽  
Martin J. Bukovac
Keyword(s):  
Field Experiments ◽  
Biological Response ◽  
Sour Cherry ◽  
Flower Initiation ◽  
Abaxial Surface ◽  
Adaxial Surface ◽  
Response Data ◽  
Time Period ◽  
Order Of Magnitude ◽  
Spur Formation

Gibberellin A3 (GA) applied to virus-infected sour cherry (Prunus cerasus L., `Montmorency') trees inhibits flower initiation and promotes spur formation. However, response to a given dose may vary. Differential foliar absorption has been suggested as a major source of this variation. Therefore, we studied if surfactants would reduce variation in GA absorption. Uptake through the abaxial surface exceeded that through the adaxial surface by about one order of magnitude (adaxial surface 1.1 vs 7.8% in 1988, 0.7 vs 16.6% in 1989). GA uptake was markedly affected by surfactants. Over a 24-hr uptake period, Activator 90 and Ortho X-77 were most effective (abaxial surface 38.3 and 37.4% in 1989), whereas Regulaid did not affect GA uptake. L-77 significantly depressed absorption (abaxial surface 9.1% in 1989). In addition to the level of uptake, surfactants also changed GA absorption kinetics. Penetration increased linearly over a 96-hr time period when Regulaid was included. However, with Ortho X-77, uptake was rapid initially but levelled off within 96 hr. These findings will be discussed in relation to biological response data obtained in the field experiments.

scholarly journals Instance Segmentation on Real time Object Detection using Mask R-CNN

2019 ◽  
Vol 9 (1) ◽  
pp. 2932-2935
Keyword(s):  
Image Processing ◽  
Search Algorithm ◽  
Human Interaction ◽  
Unique Object ◽  
Detection Of Objects ◽  
Morphological Transformations ◽  
Processing Techniques ◽  
Instance Segmentation ◽  
Image Mask ◽  
Real World Problems

In the ever-advancing field of computer vision, image processing plays a prominent role. We can extend the applications of Image processing into solving real-world problems like substantially decreasing Human interaction over the art of driving. In the process of achieving this task, we face several challenges like Segmentation and Detection of objects. The proposed thesis overcomes the challenges effectively by introducing Instance segmentation and Binary masks along with Keras and Tensorflow. Instance segmentation is used to delineate and detect every unique object of interest according to their pixel characteristics in an image. Mask RCNN is the superior model over the existing CNN models and yields accurate detection of objects more efficiently. Unlike conventional Neural Networks which employs selective search algorithm to identify object of interest, Mask RCNN employs Regional Proposal Networks(RPN) to identify object of interest. For better results Image pre-processing techniques and morphological transformations are employed to reduce the noise and increase pixel clarity

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