Synthesis of surveillance strategies via belief abstraction

We provide a novel framework for the synthesis of a controller for a robot with a surveillance objective, that is, the robot is required to maintain knowledge of the location of a moving, possibly adversarial target. We formulate this problem as a one-sided partial-information game in which the winning condition for the agent is specified as a temporal logic formula. The specification formalizes the surveillance requirement given by the user by quantifying and reasoning over the agent's beliefs about a target's location. We also incorporate additional non-surveillance tasks. In order to synthesize a surveillance strategy that meets the specification, we transform the partial-information game into a perfect-information one, using abstraction to mitigate the exponential blow-up typically incurred by such transformations. This transformation enables the use of off-the-shelf tools for reactive synthesis. We evaluate the proposed method on two case-studies, demonstrating its applicability to diverse surveillance requirements

Different Bayesian methods for updating the fatigue crack size distribution in a tubular joint

Offshore platforms are prone to fatigue damage. To evaluate the fatigue damage, these platforms are periodically inspected during the in-service lifetime. Inspection activities provide additional information, which includes detection and measurement of crack size. A Bayesian framework can be used to update the probability distribution of the uncertain parameters such as crack size. After updating the distribution of the crack size, it is possible to improve the estimation of joint reliability. The main purpose of this study is to present different methods of Bayesian inference to update the probability distribution of the crack size using the inspection results and to demonstrate how the results are different. Two different methods are presented; analytical (conjugate) and numerical methods. The advantages and shortcomings of each method are discussed. To compare the results of the analytical and numerical methods, two different situations are considered; updating the crack size distribution for a particular joint and updating the crack size distribution for several joints that have almost the same conditions. Although the proposed methodology can be applied to different kinds of structures, an example of tubular joints in a specific jacket platform is presented to demonstrate the proposed approach and to compare the results of two methods

Synthesis of minimum-cost shields for multi-agent systems

In this paper, we propose a general approach to derive runtime enforcement implementations for multiagent systems, called shields, from temporal logical specifications. Each agent of the multi-agent system is monitored, and if needed corrected, by the shield, such that a global specification is always satisfied. The different ways of how a shield can interfere with each agent in the system in case of an error introduces the need for quantitative objectives. This work is the first to discuss the shield synthesis problem with quantitative objectives. We provide several cost functions that are utilized in the multi-agent setting and provide methods for the synthesis of cost-optimal shields and fair shields, under the given assumptions on the multi-agent system. We demonstrate the applicability of our approach via a detailed case study on UAV mission planning for warehouse logistics and simulating the shielded multi-agent system on ROS/Gazebo

System reliability calculation of jacket platforms including fatigue and extreme wave loading

Jacket platforms are redundant structures. Therefore, reliability analysis at system level is more applicable than at component level. Conventionally, system reliability analysis is estimated based on either fatigue loading or extreme environmental loading. The purpose of this study is to perform the structural reliability analysis of a jacket platform under both fatigue and extreme loading. In this study the fatigue limit state is defined based on the crack size, which is obtained by a fracture mechanics approach. The probability of failure for each component is calculated by using Monte-Carlo simulation. Important failure paths are identified by using a searching process. The system failure criterion is evaluated by comparing the platform strength and loading distributions in terms of base shear. In order to define a probabilistic formula for load, a global response surface method is adopted to relate the wave height to the response of the structure. A pushover analysis is also carried out to determine the capacity of the platform. Having calculated the structure strength and loading distributions, the annual probability of failure under extreme wave is calculated and compared to the tolerable probability of failure or target reliability. An application of the approach is presented

Factors other than active relaxation responsible for the lengthening of unloaded unstriated muscle

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Detection of a redshift 3.04 filament

The filamentary structure of the early universe has until now only been seen in numerical simulations. Despite this lack of direct observational evidence, the prediction of early filamentary structure formation in a Cold Dark Matter dominated universe has become a paradigm for our understanding of galaxy assembly at high redshifts. Clearly observational confirmation is required. Lyman Break galaxies are too rare to be used as tracers of filaments and we argue that to map out filaments in the high z universe, one will need to identify classes of objects fainter than those currently accessible via the Lyman Break technique. Objects selected via their Ly-alpha emission, and/or as DLA absorbers, populate the faintest accessible part of the high redshift galaxy luminosity function, and as such make up good candidates for objects which will map out high redshift filaments. Here we present the first direct detection of a filament (at z=3.04) mapped by those classes of objects. The observations are the deepest yet to have been done in Ly-alpha imaging at high redshift, and they reveal a single string of proto-galaxies spanning about 5 Mpc (20 Mpc comoving). Expanding the cosmological test proposed by Alcock & Paczynski (1979), we outline how observations of this type can be used to determine Omega_Lambda at z=3.Comment: 5 pages, LaTeX, 3 PostScript figures; Accepted for publication in A&A-Letter

Lewis acid-induced rearrangment of α-[bis(methylthio)methylene]ethyl-2-styrylcyclopropylcarbinols: unexpected formation of a novel bicyclo[3.2.1]octadiene framework

The α-[bis(methylthio)methylene]ethyl-2-styrylcyclopropylcarbinols 9a-c undergo a simple but unexpected skeletal rearrangement in the presence of stannic chloride in nitromethane to afford bicyclo[3.2.1]octadiene derivatives 10a-c exclusively in good yields. The structure of 10a was conclusively elucidated by X-ray diffraction studies. A possible mechanism governing the formation of 10 is proposed

Wireless Charging: Its types, Standards and Applications

An electrical gadget can be powered without cords by providing electrical via an air pocket to the device in order to re-charge its capacity. The performance and practicality of cordless charging tech have noticeably enhanced lately. The introduction to cordless charging in this paper covers its basics. The evaluation of standards, which includes Qi and the A4WP, is then given, as well as a focus on their communications channels. Next, we put out a cutting-edge idea for cordless charger networking, which enables chargers to be linked for easier data gathering and management. We explain how the wireless charger network can be used to assign users to chargers, which demonstrates the usefulness in terms of a reduction costs for users to find the best chargers to recharge their mobile devices

Using Gravitational Lensing to study HI clouds at high redshift

We investigate the possibility of detecting HI emission from gravitationally lensed HI clouds (akin to damped Lyman-$\alpha$ clouds) at high redshift by carrying out deep radio observations in the fields of known cluster lenses. Such observations will be possible with present radio telescopes only if the lens substantially magnifies the flux of the HI emission. While at present this holds the only possibility of detecting the HI emission from such clouds, it has the disadvantage of being restricted to clouds that lie very close to the caustics of the lens. We find that observations at a detection threshold of 50 micro Jy at 320 MHz (possible with the GMRT) have a greater than 20% probability of detecting an HI cloud in the field of a cluster, provided the clouds have HI masses in the range 5 X 10^8 M_{\odot} < M_{HI} < 2.5 X 10^{10} M_{\odot}. The probability of detecting a cloud increases if they have larger HI masses, except in the cases where the number of HI clouds in the cluster field becomes very small. The probability of a detection at 610 MHz and 233 MHz is comparable to that at 320 MHz, though a definitive statement is difficult owing to uncertainties in the HI content at the redshifts corresponding to these frequencies. Observations at a detection threshold of 2 micro Jy (possible in the future with the SKA) are expected to detect a few HI clouds in the field of every cluster provided the clouds have HI masses in the range 2 X 10^7 M_{\odot} < M_{HI} < 10^9 M_{\odot}. Even if such observations do not result in the detection of HI clouds, they will be able to put useful constraints on the HI content of the clouds.Comment: 21 pages, 7 figures, minor changes in figures, accepted for publication in Ap