scholarly journals Minding the gap: Learning and visual scanning behaviour in nocturnal bull ants

2021 ◽  
Author(s):  
Muzahid Islam ◽  
Sudhakar Deeti ◽  
J. Frances Kamhi ◽  
Ken Cheng
Keyword(s):  
Significant Role ◽  
Initial Orientation ◽  
Complex Environments ◽  
Visual Scanning ◽  
Cluttered Environment ◽  
Spatial Changes ◽  
Familiar Environment

Insects possess small brains but exhibit sophisticated behaviour, specifically their ability to learn to navigate within complex environments. To understand how they learn to navigate in a cluttered environment, we focused on learning and visual scanning behaviour in the Australian nocturnal bull ant, Myrmecia midas, which are exceptional visual navigators. We tested how individual ants learn to detour via a gap and how they cope with substantial spatial changes over trips. Homing M. midas ants encountered a barrier on their foraging route and had to find a 50-cm gap between symmetrical large black screens, at 1m distance towards the nest direction from the centre of the releasing platform in both familiar (on-route) and semi-familiar (off-route) environments. Foragers were tested for up to 3 learning trips with the changed conditions in both environments. Results showed that on the familiar route, individual foragers learned the gap quickly compared to when they were tested in the semi-familiar environment. When the route was less familiar, and the panorama was changed, foragers were less successful at finding the gap and performed more scans on their way home. Scene familiarity thus played a significant role in visual scanning behaviour. In both on-route and off-route environments, panoramic changes significantly affected learning, initial orientation and scanning behaviour. Nevertheless, over a few trips, success at gap finding increased, visual scans were reduced, the paths became straighter, and individuals took less time to reach the goal.

scholarly journals Radio and X-ray observations of supernovae in dense environments

2017 ◽  
Vol 12 (S331) ◽  
pp. 23-32
Author(s):  
Poonam Chandra
Keyword(s):  
Significant Role ◽  
High Density ◽  
Light Curves ◽  
Core Collapse ◽  
Complex Environments ◽  
X Ray

AbstractHere we discuss the observational properties of supernovae exploding in extremely dense environments, namely Type IIn supernovae (SNe IIn). In SNe IIn, the surrounding environments play significant role in the supernovae energetics and evolution. Thus they are different than other classes of core collapse supernovae, whose energetics are not significantly altered by their environments. Though high density of medium is a prerequisite for radio and X-ray emission, less than 10% on SNe IIn are bright in these bands. This has important implications for their progenitor models. I will discuss the radio and X-ray observations of SNe IIn, which are crucial to unravel their complex environments. We also discuss some individual supernovae belonging to this class and discuss as to how they have refined our understanding of SNe IIn. Finally the importance of well sampled long term light curves in radio and X-ray bands cannot be stressed enough.

scholarly journals Robust and Efficient Trajectory Replanning Based on Guiding Path for Quadrotor Fast Autonomous Flight

2021 ◽  
Vol 13 (5) ◽  
pp. 972
Author(s):  
Yinghao Zhao ◽  
Li Yan ◽  
Yu Chen ◽  
Jicheng Dai ◽  
Yuxuan Liu
Keyword(s):  
Path Planning ◽  
Complex Environments ◽  
Adaptive Optimization ◽  
Autonomous Flight ◽  
Cluttered Environment ◽  
Surrounding Environment ◽  
Optimization Function ◽  
Aerial Vehicle ◽  
Narrow Space ◽  
Searching Method

Path planning is one of the key parts of unmanned aerial vehicle (UAV) fast autonomous flight in an unknown cluttered environment. However, real-time and stability remain a significant challenge in the field of path planning. To improve the robustness and efficiency of the path planning method in complex environments, this paper presents RETRBG, a robust and efficient trajectory replanning method based on the guiding path. Firstly, a safe guiding path is generated by using an improved A* and path pruning method, which is used to perceive the narrow space in its surrounding environment. Secondly, under the guidance of the path, a guided kinodynamic path searching method (GKPS) is devised to generate a safe, kinodynamically feasible and minimum-time initial path. Finally, an adaptive optimization function with two modes is proposed to improve the optimization quality in complex environments, which selects the optimization mode to optimize the smoothness and safety of the path according to the perception results of the guiding path. The experimental results demonstrate that the proposed method achieved good performance both in different obstacle densities and different resolutions. Compared with the other state-of-the-art methods, the quality and success rate of the planning result are significantly improved.

scholarly journals Development of Novel Average Neuro Fuzzy Hybrid Control Technique for Robot Navigation in Unknown Environments

2020 ◽  
Vol 1 (1) ◽  
Keyword(s):  
Mobile Robot ◽  
Robot Control ◽  
Fuzzy Controller ◽  
Hybrid Control ◽  
Robot Navigation ◽  
Control Technique ◽  
Complex Environments ◽  
Cluttered Environment ◽  
Neuro Fuzzy ◽  
Simulation Results

The current research focuses on development and analysis of novel Average Neuro-Fuzzy Controller for path planning and navigation of mobile robot in highly cluttered environment. During the investigation various researches related to robot, control and navigation have been analysed. For mapping the environments several distance sensors mounted on the robot are used. The sensors readings about the environments have been segmented into various sectors (front, left, right and back sectors). Using the sensors reading robots negotiate with the obstacles present in the environments during navigation from start to goal point. Experimental and simulation results obtained during the current research from various exercises are in agreement and are within 3%. Comparisons between results show the effectiveness of the proposed technique for robot navigation in complex environments. This technique can be used to address various engineering optimisation problems.

scholarly journals Collision-free kinematics for hyper-redundant manipulators in dynamic scenes using optimal velocity obstacles

2021 ◽  
Vol 18 (1) ◽  
pp. 172988142199614
Author(s):  
Liangliang Zhao ◽  
Zainan Jiang ◽  
Yongjun Sun ◽  
Jingdong Zhao ◽  
Hong Liu
Keyword(s):  
Degrees Of Freedom ◽  
Inverse Kinematic ◽  
Redundant Manipulators ◽  
Complex Environments ◽  
Dynamic Scenes ◽  
Optimal Velocity ◽  
Cluttered Environment ◽  
Different Types ◽  
Generalized Framework ◽  
Joint Limit

Hyper-redundant manipulators have been widely used in the complex and cluttered environment for achieving various kinds of tasks. In this article, we present two contributions. First, we provide a novel algorithm of relating forward and backward reaching inverse kinematic algorithm to velocity obstacles. Our optimization-based algorithm simultaneously handles the task space constraints, the joint limit constraints, and the collision-free constraints for hyper-redundant manipulators based on the generalized framework. Second, we present an extension of our inverse kinematic algorithm to collision avoidance for the hyper-redundant manipulators, where the workspaces may have different types of obstacles. We highlight the performance of our algorithm on hyper-redundant manipulators with various degrees of freedom. The results show that our algorithm has made full use of dexterity of hyper-redundant manipulators in complex environments, enhancing the performance and increasing the flexibility.

Human Event-Related Potentials to Higher-Order Acoustic Spatial Changes

2002 ◽  
Vol 16 (2) ◽  
pp. 114-118 ◽  
Author(s):  
Timo Ruusuvirta ◽  
Heikki Hämäläinen
Keyword(s):  
Working Memory ◽  
Mismatch Negativity ◽  
Spatial Information ◽  
Free Field ◽  
Event Related Potentials ◽  
Negative Polarity ◽  
Positive Polarity ◽  
Spatial Changes ◽  
Related Potentials ◽  
Human Event

Abstract Human event-related potentials (ERPs) to a tone continuously alternating between its two spatial loci of origin (middle-standards, left-standards), to repetitions of left-standards (oddball-deviants), and to the tones originally representing these repetitions presented alone (alone-deviants) were recorded in free-field conditions. During the recordings (Fz, Cz, Pz, M1, and M2 referenced to nose), the subjects watched a silent movie. Oddball-deviants elicited a spatially diffuse two-peaked deflection of positive polarity. It differed from a deflection elicited by left-standards and commenced earlier than a prominent deflection of negative polarity (N1) elicited by alone-deviants. The results are discussed in the context of the mismatch negativity (MMN) and previous findings of dissociation between spatial and non-spatial information in auditory working memory.

Visual scanning: Comparisons between student and instructor pilots.

1976 ◽  
Author(s):  
Joseph DeMaio ◽  
Stanley Parkinson ◽  
Barry Leshowitz ◽  
John Crosby
Keyword(s):  
Visual Scanning

Economic Views of L. Trotsky

2004 ◽  
pp. 142-157
Author(s):  
M. Voeikov ◽  
S. Dzarasov
Keyword(s):  
Civil War ◽  
20Th Century ◽  
Significant Role ◽  
Historical Perspective ◽  
Russian Revolution ◽  
Russian History ◽  
History Of

The paper written in the light of 125th birth anniversary of L. Trotsky analyzes the life and ideas of one of the most prominent figures in the Russian history of the 20th century. He was one of the leaders of the Russian revolution in its Bolshevik period, worked with V. Lenin and played a significant role in the Civil War. Rejected by the party bureaucracy L. Trotsky led uncompromising struggle against Stalinism, defending his own understanding of the revolutionary ideals. The authors try to explain these events in historical perspective, avoiding biases of both Stalinism and anticommunism.

The Role of Muslim Women in Civil Society In Promoting Values and Principles for Building Peace: Action Guide from The Qur’ān

Sains Insani ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 30-36
Author(s):  
Che Amnah Bahari ◽  
Fatimah Abdullah
Keyword(s):  
Civil Society ◽  
Lifelong Learning ◽  
Significant Role ◽  
Textual Analysis ◽  
Muslim Women ◽  
Peace Building ◽  
Analysis Method ◽  
Pluralistic Society ◽  
Women And Children

The whole world, the Muslim in particular has witnessed conflicts in different areas, which have hindered the developmental efforts of the nations concerned. It should be learned that most victims of these conflicts are women and children. This article attempts to elaborate the role of Muslims Women as a crucial segment in civil society in initiating peace building through nurturing process. It maintains that the adoption of the principles and values derived from the Qur’ān and Sunnah of the Prophet is necessary as a process of lifelong learning.  Those identified values constituted the framework of this article and it adopts the textual analysis method.   This article concludes that through the implementation of those values and frameworks for peace building, women as one of the important segments of civil society are able to play significant role towards initiating peace building and promoting peaceful co-existence in pluralistic society. Abstrak: Dunia Islam khususnya telah menyaksikan konflik di pelbagai daerah yang berbeza. Konflik ini telah menghalang usaha kearah pembangunan Kawasan yang berkenaan. Kebanyakan mangsa konflik ini adalah wanita dan kanak-kanak. Artikel ini cuba untuk menghuraikan peranan wanita Islam sebagai segmen penting dalam masyarakat madani dalam membangun proses kedamaian dengan mendidik dan memupuk prinsip dan nilai murni janaan al-Qur’an. Penggunaan prinsip dan nilai yang dikutip dari ayat-ayat Qur'an dan hadis Rasulullah adalah keperluan yang mendesak sebagai wadah bagi proses pembelajaran sepanjang hayat. Nilai-nilai yang dikenal pasti merupakan rangka kerja artikel ini, dan metod yang dirujuk adalah analisis teks. Artikel ini menyimpulkan bahawa melalui pelaksanaan nilai-nilai dan kerangka kerja Islam bagi proses kedamaian, wanita Islam dalam masyarakat madani mampu memainkan peranan penting dalam memulakan pembinaan keamanan dan menggalakkan kehidupan yang harmonis, sejahtera dan saling bantu membantu dalam masyarakat majmuk.

Ethnic niching in a segmented labour market: Evidence from Spain

2012 ◽  
Vol 9 (3) ◽  
pp. 249-262 ◽  
Author(s):  
Mikolaj Stanek ◽  
Alberto Veira
Keyword(s):  
Social Capital ◽  
Labour Market ◽  
Significant Role ◽  
Immigrant Workers ◽  
Structural Factors ◽  
Immigrant Communities ◽  
Logit Models ◽  
Human And Social Capital

Using the Spanish National Immigrant Survey (NIS-2007) we identify the ethnic niches where workers from five main immigrant communities concentrate. We then implement logit models in order to assess how structural factors and human and social capital variables affect the odds of working in these niches. We observe that the strong segmentation of the Spanish labour market strongly favours the concentration of immigrants in certain occupational niches. Nevertheless, variables related to human and social capital still play a significant role in the placement of immigrant workers in different niches, all of which are not equally attractive. 

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