Complexification through gradual involvement and reward providing in deep reinforcement learning

Training a relatively big neural network within the framework of deep reinforcement learning that has enough capacity for complex tasks is challenging. In real life the process of task solving requires system of knowledge, where more complex skills are built upon previously learned ones. The same way biological evolution builds new forms of life based on a previously achieved level of complexity. Inspired by that, this work proposes ways of increasing complexity, especially a way of training neural networks with smaller receptive fields and using their weights as prior knowledge for more complex successors through gradual involvement of some parts, and a way where a smaller network works as a source of reward for a more complicated one. That allows better performance in a particular case of deep Q-learning in comparison with a situation when the model tries to use a complex receptive field from scratch

Terrain relative navigation based on deep feature template matching and visual odometry

The main hurdle for terrain relative navigation systems is the incongruity of visual features between a patch of a satellite reference map and a view from an onboard UAV camera. Images are taken during different time of year, under different weather, vegetation and lighting conditions, with different angles of observation. This work proposes the usage of deep feature template matching, where features are extracted during unsupervised training using a triplet loss. It provides semantic understanding, agnostic to terrain transformations. In order to overcome struggling to navigate over featureless terrains, the work proposes additional usage of visual odometry with the procedure of sticking to the map after encountering enough features, with the procedure of hypothesizing over possible locations. Passing a fragment of the reference map through the trained feature extractor, applying an entropy filter and then a path-finding algorithm allows planning a flying path over areas rich of features relevant for navigation

ПОДХОД К ИМИТАЦИИ ПРОЦЕССА ПРИНЯТИЯ РЕШЕНИЙ В СИСТЕМЕ МОДЕЛИРОВАНИЯ ВОЕННЫХ ДЕЙСТВИЙ

The main requirement to imitating modeling of military operations adequacy. Proceeding from it is necessary that the behavior of modeling objects has been as much as possible approached to behavior of real objects in the same conditions of conditions or, at least, did not contradict logic of common sense and requirements of authorized documents. It creates necessity of working out of the mechanism, allowing to formalize administrative experience of commanders of corresponding levels and automatically to deduce decisions, on the basis of parameters of a current situation and preliminary set solving rules.As a rule, in decision-making process, the commander operates with difficult formalizable information at level of complex categories. Contrary to it, the object condition in modeling system is described in the form of a set of values of concrete parameters. For transformation of set of parameters of objects to parameters of higher level the method of the analysis of hierarchies is used.Thus there is the second problem demanding the permission synthesis of the device of decision-making on the basis of the received complex concepts. Use of the mechanism of an indistinct logic conclusion for this purpose is offered. In this case preference of a choice of this or that variant of behavior is set depending on character of crossing of the indistinct sets defined by the expert which functions of an accessory are constructed on axes generated before complex parameters. In quality konsekvents solving rules in advance generated strategy of behavior of modeling objects in this connection in offered algorithm actually there is no stage defuzzyfication act, and for accumulation of the conclusions the formula of algebraic association isused. The offered approach allows to carry out an automatic choice of alternative of behavior during modeling without participation of the operator.Главное требование к имитационному моделированию военных действий – адекватность. Исходя из этого необходимо, чтобы поведение модельных объектов было максимально приближено к поведению реальных объектов в тех же условиях обстановки или, как минимум, не противоречило логике здравого смысла и требованиям уставных документов. Это создает необходимость разработки механизма, позволяющего формализовать управленческий опыт командиров соответствующих уровней и автоматически выводить решения на основании параметров текущей ситуации и предварительно заданных решающих правил.Как правило, в процессе принятия решений, командир оперирует сложно формализуемой информацией на уровне комплексных категорий. В противоположность этому, состояние объекта в системе моделирования описывается в виде набора значений конкретных параметров. Для преобразования множества параметров объектов в параметры более высокого уровня предлагается использовать метод анализа иерархий.Вторая задача, требующая своего разрешения, синтез аппарата принятия решений на основе полученных комплексных понятий. Для этого предлагается использование механизма нечеткого логического вывода. В этом случае предпочтительность выбора того или иного варианта поведения задается в зависимости от характера пересечения определенных экспертом нечетких множеств, функции принадлежности которых построены на осях сформированных ранее комплексных параметров. В качестве консеквентов решающих правил выступают заранее сформированные стратегии поведения модельных объектов, в связи с чем в предлагаемом алгоритме фактически отсутствует этап дефаззификации, а для аккумулирования заключений используется формула алгебраического объединения. Предлагаемый подход позволяет осуществлять автоматический выбор альтернативы поведения в ходе моделирования без участия оператора

A variational derivation of P(N) equations and boundary conditions in planar and three-dimensional geometries.

Multigroup P\sb{N} theory is a widely-used approximation to multigroup transport theory. However, there are aspects of multigroup P\sb{N} theory that are not satisfactory, particularly regarding boundary conditions at a boundary having a prescribed incident flux. Historically, P\sb{N} boundary conditions at such a boundary have been assumed to be in the form given by Marshak or Mark, although Federighi and Pomraning have considered other possibilities for the case of one energy group. In this work we introduce two new variational principles. The first principle, unambiguously leads from a steady-state, first order, slab geometry multigroup transport problem to a multigroup P\sb{N} problem. The variationally-derived P\sb{N} problem consists of the conventional multigroup P\sb{N} equations and variational boundary conditions. At a boundary with a prescribed incident flux, these conditions are new and consistitute a generalization of Pomraning's boundary conditions applied to each energy group. For a vacuum boundary, these conditions reduce the Federighi's boundary condition applied to each energy group. Therefore, we refer to these newly developed P\sb{N} boundary conditions as the Generalized Federighi-Pomraning (GFP) boundary conditions. The second variational principle introduced in this work leads from a steady-state, even-parity slab geometry, multigroup transport problem to a multigroup, second-order P\sb{N} problem. This problem consists of the multigroup second-order P\sb{N} equations and Marshak boundary conditions. We generalize the second-order variational procedure to the three-dimensional geometry and obtain the general geometry multigroup second-order P\sb{N} equations and the three-dimensional Marshak-like boundary conditions. We also show how the first-order variational principle can be used to derive rigorous boundary conditions for the even-order P\sb{N} approximations and that these P\sb{N} approximations can provide accurate numerical results. Finally, a numerical comparison of the Generalized Federighi-Pomraning, Mark, Marshak and (newly developed by Larsen and Pomraning) variational-asymptotic boundary conditions shows that outside the asymptotic limit in which the variational-asymptotic and GFP boundary conditions are always superior, different boundary conditions perform best in different physical situations.Ph.D.Nuclear EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/105775/1/9208641.pdfDescription of 9208641.pdf : Restricted to UM users only

On stress, strength, and failure in asteroids during planetary entry

Efforts to characterize the danger posed by asteroids have motivated an effort to model their entry and breakup in Earth’s atmosphere. These models, crucial to planetary defense efforts, necessitate an understanding of the physics underlying fragmentation — including knowledge of key governing physical properties such as strength. Recovered meteorites provide some of the best evidence for these properties. However, their measured strengths are often orders of magnitude higher than those inferred from meteor observations. In this thesis, we seek to provide a full-field description of the stresses that develop in monolithic meteors as they enter the atmosphere and deform, to shed light on the fragmentation process. To quantify those stresses, we develop a simple model of meteor entry that treats the bolide as a deformable body subject to suitable aerodynamic, inertial, and centrifugal loads. We apply these external loads via the Meteor Equations in conjunction with modified Newtonian aerodynamic theory at high Mach numbers. First, we compute an analytical series-solution to the stress field in an idealized case and show that, unlike what is classically assumed, the tensile stresses in asteroids may be as much as 20 times lower than the ram pressure. Then, we conduct finite-element simulations of meteor falls attendant to non-ideal asteroids, and show that our conclusions hold for all but the most irregularly shaped bodies, where geometric stress concentrations may cause early fragmentation. Finally, we simulate the breakup process in select cases by recourse to the discontinuous Galerkin / Cohesive Zone method, confirming that cracks nucleate in accordance with our analytical predictions. We conclude that this factor is an important parameter in the modeling of asteroid entry and fragmentation and that, in combination with Weibull-type size-strength scaling laws, may help shed some light on the observed discrepancy between meteor and meteorite strengths.S.M

THE APPROACH TO IMMITATION DECISION-MAKING PROCESS IN SYSTEM OF MODELLING OF MILITARY OPERATIONS

The main requirement to imitating modeling of military operations adequacy. Proceeding from it is necessary that the behavior of modeling objects has been as much as possible approached to behavior of real objects in the same conditions of conditions or, at least, did not contradict logic of common sense and requirements of authorized documents. It creates necessity of working out of the mechanism, allowing to formalize administrative experience of commanders of corresponding levels and automatically to deduce decisions, on the basis of parameters of a current situation and preliminary set solving rules.As a rule, in decision-making process, the commander operates with difficult formalizable information at level of complex categories. Contrary to it, the object condition in modeling system is described in the form of a set of values of concrete parameters. For transformation of set of parameters of objects to parameters of higher level the method of the analysis of hierarchies is used.Thus there is the second problem demanding the permission synthesis of the device of decision-making on the basis of the received complex concepts. Use of the mechanism of an indistinct logic conclusion for this purpose is offered. In this case preference of a choice of this or that variant of behavior is set depending on character of crossing of the indistinct sets defined by the expert which functions of an accessory are constructed on axes generated before complex parameters. In quality konsekvents solving rules in advance generated strategy of behavior of modeling objects in this connection in offered algorithm actually there is no stage defuzzyfication act, and for accumulation of the conclusions the formula of algebraic association isused. The offered approach allows to carry out an automatic choice of alternative of behavior during modeling without participation of the operator