Constraint structure in modified Faddeev-Jackiw method

We show that in modified Faddeev-Jackiw formalism, first and second class constraints appear at each level, and the whole constraint structure is in exact correspondence with level by level method of Dirac formalism.Comment: 11 pages, No figure

Coordinated Sensor-Based Area Coverage and Cooperative Localization of a Heterogeneous Fleet of Autonomous Surface Vessels (ASVs)

Sensor coverage with fleets of robots is a complex task requiring solutions to localization, communication, navigation and basic sensor coverage. Sensor coverage of large areas is a problem that occurs in a variety of different environments from terrestrial to aerial to aquatic. In this thesis we consider the aquatic version of the problem. Given a known aquatic environment and collection of aquatic surface vehicles with known kinematic and dynamic constraints, how can a fleet of vehicles be deployed to provide sensor coverage of the surface of the body of water? Rather than considering this problem in general, in this work we consider the problem given a specific fleet consisting of one very well equipped robot aided by a number of smaller, less well equipped devices that must operate in close proximity to the main robot. A boustrophedon decomposition algorithm is developed that incorporates the motion, sensing and communication constraints imposed by the autonomous fleet. Solving the coverage problem leads to a localization/communication problem. A critical problem for a group of autonomous vehicles is ensuring that the collection operates within a common reference frame. Here we consider the problem of localizing a heterogenous collection of aquatic surface vessels within a global reference frame. We assume that one vessel -- the mother robot -- has access to global position data of high accuracy, while the other vessels -- the child robots -- utilize limited onboard sensors and sophisticated sensors on board the mother robot to localize themselves. This thesis provides details of the design of the elements of the heterogeneous fleet including the sensors and sensing algorithms along with the communication strategy used to localize all elements of the fleet within a global reference frame. Details of the robot platforms to be used in implementing a solution are also described. Simulation of the approach is used to demonstrate the effectiveness of the algorithm, and the algorithm and its components are evaluated using a fleet of ASVs

On Uniserial Modules in the Auslander-Reiten Quiver

This article begins the study of irreducible maps involving finite-dimensional uniserial modules over finite-dimensional associative algebras. We work on the classification of irreducible maps between two uniserials over triangular algebras, and give estimates for the number of middle terms of an almost split sequence with a uniserial end term.Comment: 28 pages; to be published in Journal of Algebr

Cadmium Uptake by Wheat (Triticum aestivum L.): An Overview

Cadmium is a toxic heavy metal that may be detected in soils and plants. Wheat, as a food consumed by 60% of the world's population, may uptake a high quantity of Cd through its roots and translocate Cd to the shoots and grains thus posing risks to human health. Therefore, we tried to explore the journey of Cd in wheat via a review of several papers. Cadmium may reach the root cells by some transporters (such as zinc-regulated transporter/iron-regulated transporter-like protein, low-a ffinity calcium transporters, and natural resistance-associated macrophages), and some cation channels or Cd chelates via yellow stripe 1-like proteins. In addition, some of the effective factors regarding Cd uptake into wheat, such as pH, organic matter, cation exchange capacity (CEC), Fe and Mn oxide content, and soil texture (clay content), were investigated in this paper. Increasing Fe and Mn oxide content and clay minerals may decrease the Cd uptake by plants, whereas reducing pH and CEC may increase it. In addition, the feasibility of methods to diminish Cd accumulation in wheat was studied. Amongst agronomic approaches for decreasing the uptake of Cd by wheat, using organic amendments is most effective. Using biochar might reduce the Cd accumulation in wheat grains by up to 97.8%

Event Detection in Twitter Using Multi Timing Chained Windows

Twitter is a popular microblogging and social networking service. Twitter posts are continuously generated and well suited for knowledge discovery using different data mining techniques. We present a novel near real-time approach for processing tweets and detecting events. The proposed method, Multi Timing Chained Windows (MTCW), is independent of the language of the tweets. The MTCW defines several Timing Windows and links them to each other like a chain. Indeed, in this chain, the input of the larger window will be the output of the smaller previous one. Using MTCW, the events can be detected over a few minutes. To evaluate this idea, the required dataset has been collected using the Twitter API. The results of evaluations show the accuracy and the effectiveness of our approach compared with other state-of-the-art methods in the event detection in Twitter

Awareness and attitude of radiographers towards radiation protection

    Whereas radiology departments have potential to present hazardous effects due of ionizing radiations, awareness and knowledge of application protection guidelines and instruments among radiology technicians has an important role to safe working in these places. Therefore radiographers' knowledge regarding radiation and their healthy behaviors during work time evaluated by a special questionnaire form including different relative questions. The level of participants' awareness about necessity of application film-badge and following the periodical examination were 70% and 63% respectively. Most of them are familiar with radiation adverse effects and they apply the protection devices for themselves and patients by 83.1% and 78.9%. based on the obtained data, the employees have a good awareness about construction protection especially in door shielding and wall. Their knowledge around dose limit was acceptable and there is a significant relationship between their awareness about Maximum permissible dose and their education level (p< 0.008). Taking part in different relative courses and continuously educations will affected on radiographers' awareness about  important aspects of their activities in workplace and will be ensured working with ionizing radiation.

The effect of viewing conditions on reader performance in radiographic images

Accurate interpretation of radiographic images is dependent on viewing conditions. Recently the number of radiology departments has been increased so it needs to use a workstation for reporting. The aim of this study was assess monitor performance and the effect of viewing conditions on object detection. This investigation aimed to quantify the effects of changes in box brightness and ambient light level on reader performance. Radiographs of the contrast-details phantom were taken in multiple exposures and were viewed by six observers. The viewing test was performed in 50,100 and 150 lux of ambient light in compound with 1000,1500 and 2000 cd m-2 box brightness. The percentage of uniformity was also 85. The results were analyzed by SPSS software. Low contrast visibility generally increased when the ambient light was 100 lux. The greatest performance was obtained in 2000 cd m-2 brightness and 15% non uniformity in mentioned ambient lighting. Reader performance not affected by ambient light and view box luminance although it seems those factors influenced on detection of low-contrast features in some studies.