Shape Of Swarm Research Articles

Continuous Sculpting: Persistent Swarm Shape Formation Adaptable to Local Environmental Changes

Continuous Sculpting: Persistent Swarm Shape Formation Adaptable to Local Environmental Changes

Enhancing ion mobility spectrometry performance through a programmable ion swarm shaping method based on Bradbury-Nielsen gates

The ion gate is a critical element in drift tube ion mobility spectrometry (IMS) as it directly influences the resolving power and sensitivity of the system. However, the conventional Bradbury-Nielsen gate (BNG) often leads to deformation of the ion swarm shape, resulting in reduced resolving power and significant discrimination effects. To address these limitations, we propose a novel method that incorporates a cutting phase following the gate opening. This approach effectively reduces trailing edge deformation, resulting in a maximum resolving power of over 100 and increased signal intensity. Additionally, this method maintains high resolving power even during longer gate opening times. Remarkably, this method not only significantly reduces the mobility discrimination effect but also enables the achievement of reverse discrimination by adjusting the duration of the cutting phase. Consequently, it demonstrates the potential to selectively amplify the peak height of target ions. Our method offers straightforward implementation across all IMS systems utilizing the BNG, thereby significantly improving system performance.

Human-swarm Interactions for Formation Control Using Interpreters

In this work, we develop a novel Human-Swarm Interaction (HSI) framework for formation control using the notion of an interpreter, enabling the user to control a robotic swarm's shape and formation using abstraction. The user conveys their intended commands by drawing shapes through arm gestures and motions which are recorded by an off-the-shelf wearable device. We propose a novel interpreter system, which acts as an intermediary between the user and the swarm to simplify the roles of both. The interpreter takes in high level input in the form of shapes drawn by the user, and translates it into swarm control commands by planning in the shape space using novel shape morphing dynamics (SMD), which is also used for user feedback. The proposed interpreter employs machine learning, estimation and optimal control techniques to translate the users intention into swarm control parameters. The dynamics of the swarm are realized by means of a novel decentralized formation controller based on distributed linear iterations and dynamic average consensus. Theoretical guarantees of convergence along with convergence rate of the proposed swarm controller are given. The resulting shape morphing dynamics are illustrated and discussed through simulations. The entire framework is demonstrated theoretically as well as experimentally in a 2D environment, with a human controlling a swarm of simulated robots in real time with the help of a Graphical User Environemnt (GUI).

Scaling of size, shape and surface roughness in Antarctic krill swarms

Abstract Antarctic krill are obligate swarmers and the size and shape of the swarms they form can have a major influence on trophic interactions and biogeochemical fluxes. Parameterizing variability in size and shape is therefore a useful step toward understanding the operation of the Southern Ocean ecosystem. We analyse the relationships between the length L, thickness T, perimeter P, and area A of 4650 vertical cross-sections of open-ocean krill swarms obtained within the Atlantic sector of the Southern Ocean in summer 2003. Our data show that these parameters are tightly interrelated. The thickness T increases on average as L0.67 and has a log-normal distribution within each length class. The perimeter and area scale with L and T as P∼L0.77T and A∼L0.86T0.48. The swarm aspect ratio, T/L, decreases approximately as L-0.32. The surface roughness (defined as P/A) has a weak dependence on swarm length and decreases approximately as T-0.46, which can be explained only by the appearance of indentations and cavities in the swarm shape. Overall, our study finds that there are distinct limits to the size and shape of swarms that Antarctic krill appear to be capable of forming and we explore the potential explanatory factors contributing to these limitations.

Morphogenesis in robot swarms.

Morphogenesis allows millions of cells to self-organize into intricate structures with a wide variety of functional shapes during embryonic development. This process emerges from local interactions of cells under the control of gene circuits that are identical in every cell, robust to intrinsic noise, and adaptable to changing environments. Constructing human technology with these properties presents an important opportunity in swarm robotic applications ranging from construction to exploration. Morphogenesis in nature may use two different approaches: hierarchical, top-down control or spontaneously self-organizing dynamics such as reaction-diffusion Turing patterns. Here, we provide a demonstration of purely self-organizing behaviors to create emergent morphologies in large swarms of real robots. The robots achieve this collective organization without any self-localization and instead rely entirely on local interactions with neighbors. Results show swarms of 300 robots that self-construct organic and adaptable shapes that are robust to damage. This is a step toward the emergence of functional shape formation in robot swarms following principles of self-organized morphogenetic engineering.

Swarm shape and its dynamics in a predator-swarm model

Swarm shape and its dynamics in a predator-swarm model

Observations on the behaviour of a repeatedly absconding Apis andreniformis colony in northern Thailand

SummaryI observed a colony of Apis andreniformis in a mango orchard in northern Thailand over a period of 10 days in September 2009. Here I report on colour variability of the workers, and swarm shape and movement patterns as it absconded three times in that period. Twice the swarm built comb. Workers constructed resin bands to repel ants, and defended against hornets by shimmering and forming a tail. They were not aggressive toward me. Workers on the mantle ventilated, head downwards, in the heat of the day when struck by sunlight. Dancing occurred on the crown of the swarm, all but one observed dance of short (1–2 sec) duration. One longer, staggering dance may have indicated a pending relocation by the swarm.

Variability and predictability of Antarctic krill swarm structure

Swarming is a fundamental part of the life of Euphausia superba, yet we still know very little about what drives the considerable variability in swarm shape, size and biomass. We examined swarms across the Scotia Sea in January and February 2003 using a Simrad EK60 (38 and 120 kHz) echosounder, concurrent with net sampling. The acoustic data were analysed through applying a swarm-identification algorithm and then filtering out all non-krill targets. The area, length, height, depth, packing-concentration and inter-swarm distance of 4525 swarms was derived by this method. Hierarchical clustering revealed 2 principal swarm types, which differed in both their dimensions and packing-concentrations. Type 1 swarms were generally small (<50 m long) and were not very tightly packed (<10 ind. m −3), whereas type 2 swarms were an order of magnitude larger and had packing concentrations up to 10 times greater. Further sub-divisions of these types identified small and standard swarms within the type 1 group and large and superswarms within the type 2 group. A minor group (swarm type 3) was also found, containing swarms that were isolated (>100 km away from the next swarm). The distribution of swarm types over the survey grid was examined with respect to a number of potential explanatory variables describing both the environment and the internal-state of krill (namely maturity, body length, body condition). Most variables were spatially averaged over scales of ∼100 km and so mainly had a mesoscale perspective. The exception was the level of light (photosynthetically active radiation (PAR)) for which measurements were specific to each swarm. A binary logistic model was constructed from four variables found to have significant explanatory power ( P<0.05): surface fluorescence, PAR, krill maturity and krill body length. Larger (type 2) swarms were more commonly found during nighttime or when it was overcast during the day, when surface fluorescence was low, and when the krill were small and immature. A strong pattern of diel vertical migration was not observed although the larger and denser swarms tended to occur more often at night than during the day. The vast majority of krill were contained within a minor fraction of the total number of swarms. These krill-rich swarms were more common in areas dominated by small and immature krill. We propose that, at the mesoscale level, the structure of swarms switches from being predominantly large and tightly packed to smaller and more diffuse as krill grow and mature. This pattern is further modulated according to feeding conditions and then level of light.

Multibeam echosounder observations reveal interactions between Antarctic krill and air-breathing predators

A multibeam echosounder (MBE) was deployed on an inflatable boat (length = 5.5 m) to observe swarms of Antarctic krill Euphausia superba in the nearshore environment off Livingston Island, South Shetland Islands, Antarctica. Visual observations of air-breathing predators, including penguins and fur seals, were made from the boat at the same time. MBEs extend the 2-dimensional acoustic observations that can be made with conventional vertical echosounders to 3 dimensions, enabling direct observation of the surface areas and volumes of entire krill swarms. Krill swarms exhibited a wide range of various size metrics (e.g. height, length and width) but only a narrow range of surface-area-to-volume ratios or 'roughnesses', suggesting that krill adopt a consistent group behavior to maintain swarm shape. The variation in R was investigated using generalized additive models (GAMs). GAMs indicated that the presence of air-breathing predators influenced swarm shape (R decreased as the range to predators decreased, and the swarms became more spherical), as did swarm nearest-neighbor distance (R decreased with increasing distance) and swarm position in the water column (R decreased in the upper 70% of the water column). Therefore, swarm shape appears to be influenced by a combination of behavioral responses to predator presence and environ- mental variables. MBEs have the potential to contribute much to studies of krill, and can provide data to improve our understanding of the behavior of krill in situ.

Measurement of Ion Swarm Distribution Functions in Miniature Low-Temperature Co−Fired Ceramic Ion Mobility Spectrometer Drift Tubes

Measurements of the performance of a miniature, portable 12-mm-diameter, 57-mm-length low-temperature cofired ceramic (LTCC) ion mobility spectrometer drift tube were undertaken to verify models of ion transport and determine the physical shape of the ion "swarms" in the LTCC tube. Simplified two-dimensional Gaussian models of ion swarm shape were fit to measured data to extract geometrical shape parameters. Results indicate that tube-transfer function effects that produce asymmetric ion swarms are minimized in the tube reducing temporal dispersion. Data are presented that illustrate the swarm shape as a function of gate time, electric field magnitude, and total charge in the ion swarm. Characterization and understanding of the ion transport mechanisms and effects that limit the resolution and other performance parameters of miniature IMS drift tubes is essential to the development of practical, robust, portable systems for "first responder" and homeland security missions.

Myxococcus cells respond to elastic forces in their substrate.

Elasticotaxis describes the ability of Myxococcus xanthus cells to sense and to respond to elastic forces within an agar gel on which they rest. Within 5 min of the application of stress, each cell begins to reorient its long axis perpendicular to the stress force. The cells then glide in that direction, and the swarm becomes asymmetric. A quantifiable assay for the strength of elasticotaxis is based on the change in swarm shape from circular to elliptic. By using a collection of isogenic motility mutants, it has been found that the ability to respond to stress in agar depends totally on adventurous (A) motility, but not at all on social (S) motility or on the frz genes. In fact, S- mutants (which are moving only by means of A motility) respond to the applied stress more strongly than does the wild type, despite the fact that their spreading rates are slower than that of the wt strain. Based on the swarming and elasticotactic phenotypes of isogenic frizzy strains that were also defective either in A or S motility, frz behaves as if part of the S motility system.

Biomass and population structure of a large aggregation of krill near Prydz Bay, Antarctica

Biomass and population structure of a large aggregation of krill near Prydz Bay, Antarctica