49 research outputs found
A dictionary of Sango
No full textCreated by Charles R. Taber (author) & W. J. Samarin (project director: field work collection and preparation of data).This dictionary is intended to be a companion volume to the one entitled A Grammar of Sango,* which was written in 1963 by William J. Samarin. Since the Sango language and its use are described at some length in the Grammar (i-iii), nothing further will be said in this volume
Tractable Reserve Scheduling Formulations for Alternating Current Power Grids with Uncertain Generation
No full textThe increasing penetration of wind power generation introduces uncertainty in the behaviour of electric power grids. This work is concerned with the problem of day-ahead reserve scheduling (RS) for power systems with high levels of wind power penetration, and proposes a novel set-up that incorporates an alternating current (AC) Optimal Power Flow (OPF) formulation. The OPF-RS problem is non-convex and in general hard to solve. Using a convex relaxation technique, we focus on systems with uncertain generation and formulate a chance-constrained optimization problem to determine the minimum cost of production and reserves. Following a randomization technique, we approximate the chance constraints and provide a-priori feasibility guarantees in a probabilistic sense. However, the resulting problem is computationally intractable, due to the fact that the computation time complexity grows polynomially with respect to the size of the power network and scheduling horizon. In this thesis, we first use the so-called scenario approach to approximate a convex set which contains almost surely the probability mass distribution of underlying random events. We rely on the special property of reserve scheduling problems which leads to linear constraint functions with respect to the uncertain parameters. We can therefore formulate a robust problem for only the vertices of the approximated set. Using the proposed approach, the number of scenarios is reduced significantly which is beneficial for the tractability. Such a formulation requires the power network state to only be feasible for all vertices of the convex approximated set. To even further relax such a requirement, we develop a novel RS formulation by considering the network state as a non-linear parametrization function of the uncertainty. By using a conic combination of matrices, only three positive semidefinite constraints per time step are considered. Unlike existing works in RS, our proposed parametrization has a practical meaning and is directly related to the distribution of reserve power. Such a reformulation yields a reduction in computational complexity of OPF-RS problems. Finally, we extend our results to a more realistic size of power grids, using sparsity pattern and spatiality (multi-area) decomposition of the power networks, leading to a decomposed semidefinite programming (SDP) problem. To solve the SDP in a distributed setting, we formulate a distributed consensus optimization problem, and then the alternating direction method of multipliers (ADMM) algorithm is employed to coordinate local OPF-RS problems between neighbouring areas. The theoretical developments in aforementioned cases were validated on a realistic benchmark system and a discussion on the tractability of the resulting optimization problems by means of computational time analysis is presented.Mechanical, Maritime and Materials EngineeringDelft Center for Systems and Control (DCSC
Tractable Stochastic Model Predictive Control using Conditional Value at Risk Optimization
No full textA numerically tractable Stochastic Model Predictive Control (SMPC) strategy using Conditional Value at Risk (CVaR) optimization for discrete-time linear time-invariant systems, with state and input constraints, subject to additive uncertainty, is presented. SMPC strategies make use of the probabilistic description of uncertainty to define chance constraints which allow a certain admissible level of constraint violation. SMPC strategies require the initial state of a system to be within a particular set, referred to as feasibility set, probabilistically, such that the derived control input, when applied to the system, gives rise to states that are also within the feasibility set satisfying all chance constraints on the system. This leads to recursive feasibility of the SMPC strategy. Such strategies are restrictive in nature when the uncertainty in the system is unbounded, as in the case of White Gaussian noise. In such a case, the feasibility set is very small and leads to a strategy that is very conservative. To reduce this conservatism, some constraint violations are permitted. However, such violations affect the closed-loop behaviour of the system leading to performance degradation. This performance degradation can be quantified as a penalty on the system for violating constraints, and intuitively, it can be thought of as a risk taken by the system in that undesirable state. An approach following the exact penalty method is proposed using the CVaR function to determine the penalty cost. The same optimal solution as the original constrained problem is obtained from a single unconstrained minimization. Since accurate computation of the expected value of risk using the CVaR function is not possible, a scenario-based approximation of the CVaR is used to obtain an overall tractable and computationally efficient SMPC strategy. An extensive simulation study of the double integrator system is provided to present the functionality of the proposed method.Electrical Engineerin
PREPARATION OF EDUCATIONAL CENTRE OFFICERS INTERPERSONALCO-OPERATION OF CONSCRIPTION SERVICEMEN
No full textModern tendencies of understanding the problem of military personnel preparation in educational modernization are considered in this article. The practical meaning of applying the preparation program for interpersonal cooperation is claimed.
Purpose. The article is devoted to actual educational state policy and focused on applying modern pedagogical technologies in educational process including military servicemen preparation for interpersonal cooperation in education.
Methodology. The research is based on comparative analysis, synthesis and objectivity.
Results. The author analyses the essence of the concept of interpersonal co-operation exposed by both Russian and foreign scholars and psychologists, emphasizes systematic approach and suggests realizing it in an educational organization by making servicemen preparation programs that have social and practical value.
Practical implications. Research results can be applied in the field of military and psychological and pedagogical education
REVIEW - The Psychology of Speaking in Tongues. By John P. Kildahl. Harper and Rowe
No full textThe author of this book criticizes the charismatic renewal movement. He finds fault with it because it has been disruptive and has led to irrational excesses which result in community disintegration. He, therefore judges the charismatic experience, not merely for what it does to the individual Christian, or even to those who comprise a small, select
company, but primarily for its effect on the total Christian community
Review of The silent language, by Edward T. Hall
No full textThis book on anthropology contains what at first glance looks like a Bingo board. The author describes it as "a sort of cultural equivalent of the periodic tables of chemistry" (p. 171). Both companions miss the mark. More to the point is the name "map of culture." Its purpose is to show the 100 basic complexes of activities observable in human behavior covered by the term culture
Questions and orthography in Sango
No full textTo read the Version of Record please visit http://tbt.sagepub.com/content/14/1/30.full.pdf+htmlSango is a creole language (derived from Ngbandi) spoken in the Central African Republic and adjoining parts of the Congo (Leopoldville, Chad, and Cameroon) by over one million people. The author discusses problems met with
in the course of the current translation of the OT and revision of the NT
Questions and orthography in Sango
No full textTo read the Version of Record please visit http://tbt.sagepub.com/content/14/1/30.full.pdf+htmlSango is a creole language (derived from Ngbandi) spoken in the Central African Republic and adjoining parts of the Congo (Leopoldville, Chad, and Cameroon) by over one million people. The author discusses problems met with
in the course of the current translation of the OT and revision of the NT
Review of Jamaa: a charismatic movement in Katanga, by Johannes Fabian
No full textLanguage is crucial in this description and analysis of a priest-inspired, Catholic, and African religious movement. But its task is primarily ethnographic. The author, however, is neither an 'anthropologicalinguist' nor a 'linguistic anthropologist'. The study of language was forced on him, as it were, by the phenomenon he sought to understand. The lesson he learned was that if one wanted to study rapid social change, he must study it through the material in which it is manifested, namely, language (4)
An incipient ethnic model for urban Sango
No full textIn a study to determine whether speakers of Sango could distinguish between urban and rural varieties of the language, 171 inhabitants of Bangui, capital of the Central African Republic, were asked to identify the relative age, gender, ethnicity, and provenience (urban vs. rural) of persons speaking Sango, based on tape-recorded samples. Analysis reveals that judgments were poorer than expected for age and gender, largely random for ethnicity, and interestingly suggestive for provenience. Moreover, speakers who were identified as Yakoma (or Riverine) were also associated with urbanity, a fact that implies a certain "ideal" or norm of urban Sango. This finding is linked with conclusions from other studies by the author
