Sequential decisions in the control of a space-ship (finite fuel)

1967 ◽  
Vol 4 (3) ◽  
pp. 584-604 ◽  
Author(s):  
John Bather ◽  
Herman Chernoff
Keyword(s):  
Optimal Policy ◽  
Point Of View ◽  
Control Procedure ◽  
Theoretical Point ◽  
New Approach ◽  
Final Approach ◽  
The Mean ◽  
The Difference ◽  
Miss Distance ◽  
Quadratic Case

This paper is a sequel to [1] and considers a more realistic formulation of the same question: that of finding an optimal policy for controlling the path of a space-ship as it moves towards its target. The difference here is that we no longer suppose there is an infinite quantity of fuel, always available at a fixed price, for modifying the current direction of motion. This complicates the problem of reducing the final miss distance, by introducing an extra variable. As before, we shall be particularly concerned to find a control procedure which always minimizes the mean square terminal miss. From the theoretical point of view we are also interested to see whether the techniques used to approximate the optimal policy can be extended, and how far we shall be forced to adopt a new approach. Results are derived which provide bounds on the form of the optimal policy. The derivation depends on a comparison technique whose validity is intuitively obvious, but which is still only a conjecture. However, further confirmation is obtained in the quadratic case from asymptotic expansions giving the form of the solution both when the space-ship is far away from its target and during its final approach.

Sequential decisions in the control of a space-ship (finite fuel)

1967 ◽  
Vol 4 (03) ◽  
pp. 584-604 ◽  
Author(s):  
John Bather ◽  
Herman Chernoff
Keyword(s):  
Optimal Policy ◽  
Point Of View ◽  
Control Procedure ◽  
Theoretical Point ◽  
New Approach ◽  
Final Approach ◽  
The Mean ◽  
The Difference ◽  
Miss Distance ◽  
Quadratic Case

This paper is a sequel to [1] and considers a more realistic formulation of the same question: that of finding an optimal policy for controlling the path of a space-ship as it moves towards its target. The difference here is that we no longer suppose there is an infinite quantity of fuel, always available at a fixed price, for modifying the current direction of motion. This complicates the problem of reducing the final miss distance, by introducing an extra variable. As before, we shall be particularly concerned to find a control procedure which always minimizes the mean square terminal miss. From the theoretical point of view we are also interested to see whether the techniques used to approximate the optimal policy can be extended, and how far we shall be forced to adopt a new approach. Results are derived which provide bounds on the form of the optimal policy. The derivation depends on a comparison technique whose validity is intuitively obvious, but which is still only a conjecture. However, further confirmation is obtained in the quadratic case from asymptotic expansions giving the form of the solution both when the space-ship is far away from its target and during its final approach.

A Statically Balanced Gough/Stewart-Type Platform: Conception, Design, and Simulation

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
Marco Carricato ◽  
Clément Gosselin
Keyword(s):  
Sufficient Conditions ◽  
Parallel Manipulators ◽  
Point Of View ◽  
Theoretical Point ◽  
Constant Force ◽  
Parallel Mechanisms ◽  
End Effector ◽  
Neutral Equilibrium ◽  
The Difference ◽  
Elastic Elements

Gravity compensation of spatial parallel manipulators is a relatively recent topic of investigation. Perfect balancing has been accomplished, so far, only for parallel mechanisms in which the weight of the moving platform is sustained by legs comprising purely rotational joints. Indeed, balancing of parallel mechanisms with translational actuators, which are among the most common ones, has been traditionally thought possible only by resorting to additional legs containing no prismatic joints between the base and the end-effector. This paper presents the conceptual and mechanical designs of a balanced Gough/Stewart-type manipulator, in which the weight of the platform is entirely sustained by the legs comprising the extensible jacks. By the integrated action of both elastic elements and counterweights, each leg is statically balanced and it generates, at its tip, a constant force contributing to maintaining the end-effector in equilibrium in any admissible configuration. If no elastic elements are used, the resulting manipulator is balanced with respect to the shaking force too. The performance of a study prototype is simulated via a model in both static and dynamic conditions, in order to prove the feasibility of the proposed design. The effects of imperfect balancing, due to the difference between the payload inertial characteristics and the theoretical/nominal ones, are investigated. Under a theoretical point of view, formal and novel derivations are provided of the necessary and sufficient conditions allowing (i) a body arbitrarily rotating in space to rest in neutral equilibrium under the action of general constant-force generators, (ii) a body pivoting about a universal joint and acted upon by a number of zero-free-length springs to exhibit constant potential energy, and (iii) a leg of a Gough/Stewart-type manipulator to operate as a constant-force generator.

The Effect of Waking Suggestion on Post-Hypnotic Amnesia

1981 ◽  
Vol 11 (1) ◽  
pp. 44-46 ◽  
Author(s):  
D.P. Fourie
Keyword(s):  
Point Of View ◽  
The Other ◽  
Hypnotic Susceptibility ◽  
The Subject ◽  
The Mean ◽  
The Difference ◽  
The One ◽  
The Relationship ◽  
Female Subjects

It is increasingly realized that hypnosis may be seen from an interpersonal point of view, meaning that it forms part of the relationship between the hypnotist and the subject. From this premise it follows that what goes on in the relationship prior to hypnosis probably has an influence on the hypnosis. Certain of these prior occurences can then be seen as waking suggestionns (however implicitly given) that the subject should behave in a certain way with regard to the subsequent hypnosis. A study was conducted to test the hypothesis that waking suggestions regarding post-hypnotic amnesia are effective. Eighteen female subjects were randomly divided into two groups. The groups listened to a tape-recorded talk on hypnosis in which for the one group amnesia for the subsequent hypnotic experience and for the other group no such amnesia was suggested. Thereafter the Stanford Hypnotic Susceptibility Scale was administered to all subjects. Only the interrogation part of the amnesia item of the scale was administered. The subjects to whom post-hypnotic amnesia was suggested tended to score lower on the amnesia item than the other subjects, as was expected, but the difference between the mean amnesia scores of the two groups was not significant.

scholarly journals Bipartite Structures in Social Networks: Traditional versus Entropy-Driven Analyses

Entropy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 277
Author(s):  
Wilhelm Rödder ◽  
Andreas Dellnitz ◽  
Friedhelm Kulmann ◽  
Sebastian Litzinger ◽  
Elmar Reucher
Keyword(s):  
Social Networks ◽  
Maximum Entropy ◽  
Point Of View ◽  
Theoretical Point ◽  
Generic Structure ◽  
New Approach ◽  
Affiliation Networks ◽  
Principle Of Maximum Entropy ◽  
Affiliation Network ◽  
Principle Of Maximum

A special type of social networks is the so-called affiliation network, consisting of two modes of vertices: actors and events. Up to now, in the undirected case, the closeness of actors in such networks has been measured by their jointly-attended events. Indirect contacts and attenuated and directed links are of minor interest in affiliation networks. These flaws make a veritable estimation of, e.g., possible message transfers amongst actors questionable. In this contribution, first, we discuss these matters from a graph-theoretical point of view. Second, so as to avoid the identified weaknesses, we propose an up-and-coming entropy-based approach for modeling such networks in their generic structure, replacing directed (attenuated) links by conditionals: if-then. In this framework, the contribution of actors and events to a reliable message transfer from one actor to another—even via intermediaries—is then calculated applying the principle of maximum entropy. The usefulness of this new approach is demonstrated by the analysis of an affiliation network called “corporate directors”.

A new approach to the measurement of the quantitative effects of inherent and environmental factors on the composition of the milk of individual cows and of herds, with particular reference to lactose content

1968 ◽  
Vol 35 (1) ◽  
pp. 91-105 ◽  
Author(s):  
J. P. Walsh ◽  
J. A. F. Rook ◽  
F. H. Dodd
Keyword(s):  
Quantitative Estimation ◽  
Relative Importance ◽  
New Approach ◽  
Mean Values ◽  
Stage Of Lactation ◽  
Bulk Milk ◽  
Wide Range ◽  
The Mean ◽  
The Difference ◽  
Effect Of Age

Summary(1) A tentative scheme is proposed for the quantitative estimation of the effects of various factors on one major milk constituent, lactose, from analyses of the milk of individual cows within herds. The potential lactose content in the milk of individual cows is predicted from the observed potassium-to-lactose ratio in the milk, and the difference between the predicted potential and the actual lactose content is partitioned into fractions that are attributed to effects due to age, inter-quarter difference and changes with stage of lactation. The scheme was applied to 2 commercial herds, one (herd A) producing milk of low and the other (herd B) milk of normal SNF content.(2) Lactation mean values for fat, SNF and lactose contents of the milk of individual cows showed a wide range of the same order in each of the 2 herds. Of the mean difference in SNF percentage of 0·30 between the herds, 0·14, or 47%, was due to a difference in lactose content.(3) The predicted potential milk lactose content of the cows in the 2 herds ranged from 5·04 to 5·66 (g/100 g milk water). Herd mean values were 5·394 for herd A and 5·244 for herd B.(4) Herd mean values for the effect on the lactose content (g/100 g milk water) of age, of changes with stage of lactation and of inter-quarter difference were −0·127, −0·080, and 0·073 respectively in herd A, and −0·197, −0·058 and −0·078, respectively, in herd B.(5) The relative importance of the various factors in accounting for differences between the herds in the lactose content of their bulk milk were: predicted potential lactose content 61%, effect of age 28%, effect of changes with stage of lactation 9% and effect of inter-quarter difference 2%.(6) The errors attached to the estimation of potential milk lactose content and the effects of age, of changes with stage of lactation and of inter-quarter difference are discussed.

scholarly journals The comparative method for policy studies: the thorny aspects

2019 ◽  
Vol 10 (1) ◽  
pp. 56-67
Author(s):  
Tatiana-Camelia Dogaru Cruceanu
Keyword(s):  
Comparative Research ◽  
Comparative Method ◽  
Policy Research ◽  
Point Of View ◽  
Decision Makers ◽  
Theoretical Point ◽  
Policy Studies ◽  
New Approach ◽  
The Past ◽  
Policy Systems

Abstract Over the past decades, the comparative method has attracted the attention of the theorists, and studies based on this approach have increased in applied policy research. In their daily and strategically policy decisions, the decision makers from local, regional and national levels use more and more the comparative research methods, especially due to interlinked relationship and the need for bench learning and benchmarking practices. The comparative method allows the actors to analyse other experiences, and thus to take decisions more efficient. This is a normal, an inevitable situation, when the unit of analysis is a country, a field of matters or a process where researchers compare cases from empirical or theoretical point of view. The purpose of this paper is to provide a critical view on the capacity of comparative method to foster knowledge in policy studies. The intention is to see and to explore the utility of comparative method for policy studies and policy analysis, since a new approach “evidence-based policymaking” arise, emphasising the importance of using evidence from other political and policy systems.

scholarly journals From the Kalman Filter to the Particle Filter: A Geometrical Perspective of the Curse of Dimensionality

2016 ◽  
Vol 2016 ◽  
pp. 1-18
Author(s):  
Olivier Pannekoucke ◽  
Pierrick Cébron ◽  
Niels Oger ◽  
Philippe Arbogast
Keyword(s):  
Kalman Filter ◽  
Particle Filter ◽  
High Dimension ◽  
Convergence Property ◽  
Curse Of Dimensionality ◽  
Finite Sample ◽  
New Approach ◽  
The Mean ◽  
Finite Sampling ◽  
The Difference

The aim of this contribution is to provide a description of the difference between Kalman filter and particle filter when the state space is of high dimension. In the Gaussian framework, KF and PF give the same theoretical result. However, in high dimension and using finite sampling for the Gaussian distribution, the PF is not able to reproduce the solution produced by the KF. This discrepancy is highlighted from the convergence property of the Gaussian law toward a hypersphere: in high dimension, any finite sample of a Gaussian law lies within a hypersphere centered in the mean of the Gaussian law and of radius square-root of the trace of the covariance matrix. This concentration of probability suggests the use of norm as a criterium that discriminates whether a forecast sample can be compatible or not with a given analysis state. The contribution illustrates important characteristics that have to be considered for the high dimension but does not introduce a new approach to face the curse of dimensionality.

Study on Improvement of Analytic Depletion Calculation Method

2013 ◽  
Author(s):  
Kai Huang ◽  
Hongchun Wu ◽  
Liangzhi Cao ◽  
Youqi Zheng
Keyword(s):  
Trajectory Analysis ◽  
Time Integration ◽  
Concentration Function ◽  
Point Of View ◽  
Reading Process ◽  
Theoretical Point ◽  
Calculation Algorithm ◽  
Programming Technique ◽  
New Approach ◽  
Time Consumption

The transmutation trajectory analysis (TTA) method is a traditional analytic depletion calculation algorithm. It’s capable of providing very accurate solutions with cutoff value being sufficiently small, but the main drawback is expensive time consumption. In this paper, the depletion problem was rephrased as a directed-graph module with additional properties attributed to vertices and edges. Based on this model a new approach for TTA implementation was conducted, to which dynamic programming technique could be introduced easily. Besides it, a new analytic algorithm is proposed based on the above model, which gives each nuclide a time dependent concentration function instead of a scalar value that other algorithms could only offer. One of the advantages brought by this algorithm is making time integration value calculations straightforward. Both of these two approaches are programmed. The resulting TTA code was proved to be very efficient, the running time for a typical ORIGEN2 problem with cutoff equals to 10−15 could be of the same magnitude with time spent on library reading process. The codes are analyzed in terms of time and space complexities, which could offer a theoretical point of view on their behaves.

scholarly journals SHELL WORDS IN ANATOMY A CONTRASTIVE STUDY OF BULGARIAN AND ENGLISH ANATOMICAL SYSTEMS

2018 ◽  
Vol 28 (7) ◽  
pp. 2283-2287
Author(s):  
Ivaylo Dagnev ◽  
Mariya Saykova ◽  
Maya Yaneva
Keyword(s):  
Point Of View ◽  
Semantic Features ◽  
Theoretical Point ◽  
Contrastive Study ◽  
Anatomical Terminology ◽  
General Terms ◽  
Reference Potential ◽  
The Difference ◽  
Anatomical Objects ◽  
Shell Nouns

Shell words are a particular category of lexemes that make up an open-ended functionally defined class of abstract nouns having the potential to be as conceptual shells for complex, proposition-like pieces of information. Examples include: “fact”, “case”, “idea”, “problem”, “position”, “cause”, “situation”, “something”, etc. The idea of a particular class of words that group semantic features, but are not related to a referent is also found in many authors. Such words have greater reference potential and thus become useful for naming different referents (onomasiological salience). From a theoretical point of view, the need for a context to determine the meaning of a single lexeme is in fact equivalent to deleting the difference between polysemy and vagueness. Shell nouns are indexical words or "hollow words, envelopes" because their meaning is incomplete; they only point to what can fill the envelope, but still give it some structure. Thus, the meaning associated with these shell units is both context-related and in turn generates a linguistic context. At first glance it seems strange that generalized words such as shells are not hyperonimic, but in connection with the nature of the anatomical terms (physically perceived) it is important to note that it is precisely words from the basic level that are conceptualized as sensory and functional gestalts. The eventual clash between the specificity of the object and the abstract nature of terms causes the conflict in terminology. Once again, the choice of a linguistic rather than a terminological approach to the names of the anatomical objects is argued. The current research assumes that shell function may be applicable to specific nouns, i.e. anatomical terms, the so-called termini generales. In both Bulgarian and English anatomical terminologies, there are about 190 such terms that are head words in anatomical expressions and occur in all parts of anatomy, e.g. terms such as: glava (en – head), greben (en – crest), gynka (en –fold), klon (en – branch), list (en – leaf), plocha (en – plate), sloy (en – layer), tyalo (en – body), vryzka (en – “link”, “connection”), etc. What is special about them is that with their help are formed the names of organs in the different systems. Their semantic value is contextually defined. They "mark” large branches in the anatomical terminology system and are expressions of terminological multiplicity. Obtained through specialization of commonly used nouns, general terms are a manifestation of re-terminologization through metaphorical projection. In our view, termini generales have lost their metaphorical status (if they have one) and some of them serve as shell nouns. We also perform a cross-linguistic Bulgarian – English analysis of shells in both anatomical systems.

scholarly journals Durata e costo delle visite in medicina generale: il progetto DYSCO

2003 ◽  
Vol 4 (2) ◽  
pp. 109-114 ◽  
Author(s):  
Livio Garattini ◽  
Emanuela Castelnuovo ◽  
Davide Lanzeni ◽  
Cecilia Viscarra ◽  
DYSCO VISITE Gruppo di studio DYSCO VISITE
Keyword(s):  
Methodological Approach ◽  
Point Of View ◽  
Theoretical Point ◽  
Ambulatory Visit ◽  
Real Cost ◽  
Number Of Patients ◽  
Travelling Time ◽  
The Mean ◽  
Number Of Visits ◽  
The Times

In Italy, general practitioners (GPs) operating within the National Health Service (NHS) are paid according to the number of patients followed, without relation to the number of visits performed. This means that, from a theoretical point of view, the marginal cost of an adjunctive medical examination equals to zero. Since this view is clearly little realistic, in this paper we expose a methodological approach to estimate the real cost of a GP visit, starting from data collected in the DYSCO study, a national survey on the medical costs of dystimia in Italy. 46 GPs were asked to record the number and duration of ambulatory and domiciliar visits, along with the time spent in administrative tasks, during 4 weeks, each randomly chosen within a season (spring, summer, autumn, winter). In order to assign a monetary value to each visit, the total fee reimbursed by the NHS to a GP was divided by the total time spent on work, and then again by the number of visits conducted during this time. The calculations performed revealed that the mean duration of a ambulatory visit amounts to about 10 minutes, while a domiciliar visit (including travelling time) lasts almost the double. An interesting result was that summer visits have significantly longer duration than the mean, and consequently cost more. The mean cost of a GP’s ambulatory visit resulted about 12 Euro; a domiciliar visit costs almost 23 Euro. The times and costs calculated in this study are consistent with other calculations performed by other authors in Europe and Italy, confirming the appropriateness of the employed methodology.

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