14,164 research outputs found
A Hormone Inspired System for On-line Adaptation in Swarm Robotic Systems
Individual robots, while providing the opportunity to develop a bespoke and specialised system, suffer in terms of performance when it comes to executing a large number of concurrent tasks. In some cases it is possible to drastically increase the speed of task execution by adding more agents to a system, however this comes at a cost. By mass producing relatively simple robots, costs can be kept low while still gaining the benefit of large scale multi-tasking. This approach sits at the core of swarm robotics.
Robot swarms excel in tasks that rely heavily on their ability to multi-task, rather than applications that require bespoke actuation. Swarm suited tasks include: exploration, transportation or operation in dangerous environments. Swarms are particularly suited to hazardous environments due to the inherent expendability that comes with having multiple, decentralised agents. However, due to the variance in the environments a swarm may explore and their need to remain decentralised, a level of adaptability is required of them that can't be provided before a task begins. Methods of novel hormone-inspired robotic control are proposed in this thesis, offering solutions to these problems. These hormone inspired systems, or virtual hormones, provide an on-line method for adaptation that operates while a task is executed. These virtual hormones respond to environmental interactions. Then, through a mixture of decay and stimulant, provide values that grant contextually relevant information to individual robots. These values can then be used in decision making regarding parameters and behavioural changes.
The hormone inspired systems presented in this thesis are found to be effective in mid-task adaptation, allowing robots to improve their effectiveness with minimal user interaction. It is also found that it is possible to deploy amalgamations of multiple hormone systems, controlling robots at multiple levels, enabling swarms to achieve strong, energy-efficient, performance
Explosive Jumping: Extreme Morphological and Physiological Specializations of Australian Rocket Frogs (Litoria nasuta)
Anuran jumping is an ideal system for examining the relationships between key morphological, physiological, and kinematic parameters. We used the Australian rocket frog (Litoria nasuta) as a model species to investigate extreme specialization of the vertebrate locomotor system for jumping. We measured the ground reaction forces applied during maximal jumps using a custom-designed force platform, which allowed us to calculate instantaneous measures of acceleration, velocity, power output, and total jump distance. We quantified the mechanical properties of the plantaris longus muscle using the work loop technique. We found that L. nasuta achieved the second-longest relative jumping distance for any anuran (55.2 body lengths for one individual) and the highest published anuran values for isolated net mean muscle power output measured using work loops (93.5 W kg(-1) muscle mass), hindlimb length to snout-vent length ratio (2.02), and relative hindlimb muscle mass (33% of body mass). Litoria nasuta also had a higher ratio of tibia length to snout-vent length than 19 related species. We found that the mean power output expended during the takeoff phase of jumping in the individual that jumped the farthest was about three times greater than our estimate of available muscle power output
U.S. Biodiesel Development: New Markets for Conventional and Genetically Modified Agricultural Products
With environmental and energy source concerns on the rise, using agricultural fats and oils as fuel in diesel engines has captured increasing attention. Substituting petroleum diesel with biodiesel may reduce air emissions, increase the domestic supply of fuel, and create new markets for farmers. U.S. agricultural fats and oils could support a large amount of biodiesel, but high production costs and competing uses for biodiesel feedstocks will likely prevent mass adoption of biodiesel fuel. Higher-priced niche markets could develop for biodiesels as a result of environmental regulations. Biodiesel has many environmental advantages relative to petroleum diesel, such as lower CO, CO2, SOx, and particulate matter emissions. Enhancing fuel properties by genetically modifiying oil crops could improve NOx emissions, cold flow, and oxidative stability, which have been identified as potential problems for biodiesel. Research activities need to be directed toward cost reduction, improving fuel properties, and analyzing the economic effects of biodiesel development on U.S. agriculture.biodiesel, biodiesel blends, fatty acid esters, soybean, oil crops, animal fats, plant genetics, diesel engines, alternative fuels, Resource /Energy Economics and Policy,
Development of models for the sodium version of the two-phase three dimensional thermal hydraulics code THERMIT
Several different models and correlations were developed
and incorporated in the sodium version of THERMIT, a thermal-
hydraulics code written at MIT for the purpose of analyzing
transients under LMFBR conditions. This includes: a mechanism
for the inclusion of radial heat conduction in the sodium coolant
as well as radial heat loss to the structure surrounding the test
section. The fuel rod conduction scheme was modified to allow
for more flexibility in modelling the gas plenum regions and
fuel restructuring. The formulas for mass and momentum exchange
between the liquid and vapor phases were improved. The single
phase and two phase friction factors were replaced by correlations
more appropriate to LMFBR assembly geometry.
The models incorporated in THERMIT were tested by running
the code to simulate the results of the THORS Bundle 6A experiments
performed at Oak Ridge National Laboratory. The results demonstrate
the increased accuracy provided by the inclusion of these effects."Sponsored by U.S Department of Energy, General Electric Co. and Hanford Engineering Development Laboratory.
Centralizing the International Operations of Multinationals
The thesis to this Article is that, ideally, international decision making should be managed from a central control point, leaving day-to-day management and operational control within each of the operating locations. The purpose of the central location would be, basically, to get an overview of the world, to put together the pieces of the global enterprise in such a manner as to be able to take advantage of the shifting trade, financial, monetary and development whims of not only the free world but, more recently, the communist world which is wont to enter the international monetary and development markets in a major way
Friendly Fire in a Simulated Firearms Task
Factors such as poor visibility, lack of situation awareness and bad communication have been shown to contribute to friendly fire incidents. However, to the authors’ knowledge, an individual’s ability to inhibit their motor response of shooting when a non-target is presented has not been investigated. This phenomenon has been modeled empirically using the Sustained Attention to Response Task (SART; Robertson, Manly, Andrade, Baddeley, & Yiend, 1997) computer task. The SART is generally a high Go/low No-Go detection task whereby participants respond to numerous neutral stimuli and withhold to rare targets. In the current investigation, we further investigate the SART using a simulated small arms scenario to test whether lack of motor response inhibition can be modeled in a more ecologically valid environment. Additionally, we were interested in how error rates were impacted in low Go/high No-Go versions of the task. Thirteen university students completed a computer and simulated small arms scenario in a SART and low Go condition. Both the computer and small arms scenario revealed similar speed-accuracy trade-offs indicating participants’ inability to halt their pre-potent responses to targets even in a more ecologically valid environment. The SART may be used in future studies to model friendly fire scenarios
EVIDENCE-SCIENTIFIC TESTS FOR lNTOXICATION-ADMISSIBILITY
It is the purpose of this comment to examine the admissibility and probative value of the tests available for determining the amount of alcohol in the human system
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