263 research outputs found

    Rendezvous on a Known Dynamic Point on a Finite Unoriented Grid

    Full text link
    In this paper, we have considered two fully synchronous OBLOT\mathcal{OBLOT} robots having no agreement on coordinates entering a finite unoriented grid through a door vertex at a corner, one by one. There is a resource that can move around the grid synchronously with the robots until it gets co-located along with at least one robot. Assuming the robots can see and identify the resource, we consider the problem where the robots must meet at the location of this dynamic resource within finite rounds. We name this problem "Rendezvous on a Known Dynamic Point". Here, we have provided an algorithm for the two robots to gather at the location of the dynamic resource. We have also provided a lower bound on time for this problem and showed that with certain assumption on the waiting time of the resource on a single vertex, the algorithm provided is time optimal. We have also shown that it is impossible to solve this problem if the scheduler considered is semi-synchronous

    Space and move-optimal Arbitrary Pattern Formation on infinite rectangular grid by Oblivious Robot Swarm

    Full text link
    Arbitrary Pattern Formation (APF) is a fundamental coordination problem in swarm robotics. It requires a set of autonomous robots (mobile computing units) to form any arbitrary pattern (given as input) starting from any initial pattern. The APF problem is well-studied in both continuous and discrete settings. This work concerns the discrete version of the problem. A set of robots is placed on the nodes of an infinite rectangular grid graph embedded in a euclidean plane. The movements of the robots are restricted to one of the four neighboring grid nodes from its current position. The robots are autonomous, anonymous, identical, and homogeneous, and operate Look-Compute-Move cycles. Here we have considered the classical OBLOT\mathcal{OBLOT} robot model, i.e., the robots have no persistent memory and no explicit means of communication. The robots have full unobstructed visibility. This work proposes an algorithm that solves the APF problem in a fully asynchronous scheduler under this setting assuming the initial configuration is asymmetric. The considered performance measures of the algorithm are space and number of moves required for the robots. The algorithm is asymptotically move-optimal. A definition of the space-complexity is presented here. We observe an obvious lower bound D\mathcal{D} of the space complexity and show that the proposed algorithm has the space complexity D+4\mathcal{D}+4. On comparing with previous related works, we show that this is the first proposed algorithm considering OBLOT\mathcal{OBLOT} robot model that is asymptotically move-optimal and has the least space complexity which is almost optimal

    Asynchronous Gathering of Robots with Finite Memory on a Circle under Limited Visibility

    Full text link
    Consider a set of nn mobile entities, called robots, located and operating on a continuous circle, i.e., all robots are initially in distinct locations on a circle. The \textit{gathering} problem asks to design a distributed algorithm that allows the robots to assemble at a point on the circle. Robots are anonymous, identical, and homogeneous. Robots operate in a deterministic Look-Compute-Move cycle within the circular path. Robots agree on the clockwise direction. The robot's movement is rigid and they have limited visibility π\pi, i.e., each robot can only see the points of the circle which is at an angular distance strictly less than π\pi from the robot. Di Luna \textit{et al}. [DISC'2020] provided a deterministic gathering algorithm of oblivious and silent robots on a circle in semi-synchronous (\textsc{SSync}) scheduler. Buchin \textit{et al}. [IPDPS(W)'2021] showed that, under full visibility, OBLOT\mathcal{OBLOT} robot model with \textsc{SSync} scheduler is incomparable to FSTA\mathcal{FSTA} robot (robots are silent but have finite persistent memory) model with asynchronous (\textsc{ASync}) scheduler. Under limited visibility, this comparison is still unanswered. So, this work extends the work of Di Luna \textit{et al}. [DISC'2020] under \textsc{ASync} scheduler for FSTA\mathcal{FSTA} robot model

    Arbitrary Pattern Formation on a Continuous Circle by Oblivious Robot Swarm

    Full text link
    In the field of distributed system, Arbitrary Pattern Formation (APF) problem is an extensively studied problem. The purpose of APF is to design an algorithm to move a swarm of robots to a particular position on an environment (discrete or continuous) such that the swarm can form a specific but arbitrary pattern given previously to every robot as an input. In this paper the solvability of the APF problem on a continuous circle has been discussed for a swarm of oblivious and silent robots without chirality under a semi synchronous scheduler. Firstly a class of configurations called \textit{Formable Configuration}(FCFC) has been provided which is necessary to solve the APF problem on a continuous circle. Then considering the initial configuration to be an FCFC, an deterministic and distributed algorithm has been provided that solves the APF problem for nn robots on a continuous circle of fixed radius within O(n)O(n) epochs without collision

    Circle Formation by Asynchronous Opaque Fat Robots on an Infinite Grid

    Full text link
    This study addresses the problem of "Circle Formation on an Infinite Grid by Fat Robots" (CF_FAT_GRIDCF\_FAT\_GRID). Unlike prior work focused solely on point robots in discrete domain, it introduces fat robots to circle formation on an infinite grid, aligning with practicality as even small robots inherently possess dimensions. The algorithm, named CIRCLE_FGCIRCLE\_FG, resolves the CF_FAT_GRIDCF\_FAT\_GRID problem using a swarm of fat luminous robots. Operating under an asynchronous scheduler, it achieves this with five distinct colors and by leveraging one-axis agreement among the robots

    Morbidity profile of 2 months-5years children according to IMNCI classification in paediatrics outpatient department of tertiary care hospital, Joka, Kolkata, India

    Get PDF
    Background: Every year, more than 10 million children die in developing countries before they reach their fifth birthday. Seven in 10 of these deaths are due to acute respiratory infections mostly pneumonia, diarrhoea, measles, malnutrition & combination of these illnesses. The rationale of our study is to assess the profile of childhood illness in the paediatrics out- patient department at ESI-PGIMSR and MC, Joka, Kolkata, India so that the same burden can be minimised & to promote healthy upbringing of children below five years of age.Methods: This was an observational study of cross-sectional design conducted among the mother-child pair (child belonging to the age group of 2 months-5 years) visiting Pediatrics OPD during the study period i.e. 4 weeks. Convenience sampling method was used. The participants whose guardians did not give consent for the study & were seriously ill were excluded from this study.  A pre-designed and pre-tested interview schedule was used. After giving a brief introduction about the topic, verbal consent was taken & face to face interview was conducted in local language. Data was compiled & computed in SPSS software version 20.Results: According to the IMNCI classification, 15.9% of the study subjects had severe pneumonia, 17.8% had pneumonia. 1.9% of the study subjects had severe dehydration. None of the respondents presented with some dehydration. Only 1% of the respondents presented with anemia. 4.9% of the respondents presented with severe malnutrition, 13.8% of them had malnutrition according to IMNCI classification.31.7% of the respondents had primary immunisation.67.3% of them had been breastfed. Among them 41.2% of them were breastfed 8 times & more a day.92% of them had supplementary feeding as rice, 33.3% of them had supplementary feeding as baby food. 69.3% of them had complained of change in food habit during illness.Conclusions: Proper counselling to parents regarding prevention of common morbidities like pneumonia, diarrhoea, malnutrition etc. should be provided at each and every possible hospital contact. Awareness about danger signs & symptoms of urgent hospitalisation should be imparted using pamphlets or other health educational materials. Health workers also should undergo proper training so that proper classification of the conditions as well as efficient management could be provided

    Ex-situ Studies of Captive Breeding of Ompok bimaculatus (Bloch, 1794) in Tripura

    Get PDF
    Broodstock (37 males and 83 females) of Ompok bimaculatus was sampled from Rivers Feni, Muhuri, Gomoti and also from Hurijala wetland of Tripura during November 2008 to February 2010. During sampling of fish species, water samples from different locations were also sampled in order to know the water quality characteristics of the habitat. The broodstock was provided specific live feed and water quality during acclimatization. The maturity cycle of the species was examined with gonad during the monsoon period. During breeding season the gravid females and males were identified with some specific phenotypic characteristics. Induced spawning was done under some particular aquaculture conditions only

    EFFECT OF ULTRA-DILUTED HISTAMINE ON HYPOXIC CHICK LUNG TISSUE INFLAMMATORY CHANGES

    Get PDF
    Objectives: Since its discovery, the role of histamine in inflammation is controversial; thus, according to some authority, it is mainly pro-inflammatory, and according to others, it is anti-inflammatory in nature. In this scenario, we thought that the contradictory results are dose dependent, thus in this study, our aim was to find the specific role of ultra-diluted histamine in pulmonary inflammation. Materials and Methods: Ultra-diluted histamine ( ~1 pg/ml) was administered in chick lung hypoxic inflammation in an restricted organoid culture along with lysozyme, ovalbumin, and blank controls. Results: The ultra-diluted histamine showed a significant role as an anti-inflammatory and bronchodilator agent and the anti-inflammatory action was found similar to lysozyme. Conclusion: Ultra-diluted histamine may be used as an anti-inflammatory agent

    Glacier-Surface Velocity Derived Ice Volume and Retreat Assessment in the Dhauliganga Basin, Central Himalaya – A Remote Sensing and Modeling Based Approach

    Get PDF
    Himalayan glaciers are a storehouse of fresh water and play a significant role in influencing the runoff through numerous perennial rivers flowing over the Indo-Gangetic plains, providing freshwater to the second largest populated country in the world. For suitable management of this water resource, measurement of glacier-ice volume is extremely important in the current scenario of climate change and water scarcity. To address this concern, the present study endeavors to find a suitable methodology to quantify glacier volume and retreat in the Central Himalaya. Herein, two methods were implemented to estimate the total glacier ice volume – conventional area-based scaling method and glacier-surface velocity based modeling technique. The availability of field data allowed a validation assessment to be carried out on two Himalayan glaciers (Chhota Shigri and Satopanth). Here, we propose a volume-area power law, appropriate for the application in the context of Himalayan glaciers. The ice volume of 15 glaciers larger than 1 km2 calculated using a spatially distributed ice thickness model is 3.78 × 109 m3 (f = 0.8), with an overall uncertainty of 18.4%. The total volume of the remaining glaciers in the basin, calculated using a tuned volume-area scaling relation is 2.71 × 109 m3. A sensitivity analysis is performed to evaluate the influence of input parameters on the model and volume-area scaling performance. The study also incorporates investigation of the glacier bed topography for discrete identification of the overdeepening sites in the glacier valley which are potential lake formation sites in the future. A total of 54 overdeepening sites covering an area of 2.85 km2 have been identified. In addition, the relative glacier area loss of the glaciers is investigated using historical CORONA and Landsat satellite imageries. Glaciers with a smaller area and those with lower mean ice thickness near the terminus shrank significantly more, as compared to the larger ones. The total area of the selected larger glaciers is estimated to be 68 km2 in 2015 and deglaciation of 4.7 km2 is observed over the period of 48 years that accounts for 6.9% of the total area in 1968
    corecore