Equal Probability Of Occurrence Research Articles

Reshaping structural hysteresis response with semi-active viscous damping

Semi-active control devices offer significant promise for their ability to add supplemental damping and reduce seismic structural responses in an easily controllable manner, and can be used to modify or reshape overall structural hysteretic response. This study uses a spectral analysis of semi-active viscous dampers to compare the impact of three methods of re-shaping structural hysteretic dynamics that resist: motion in all 4 quadrants (1–4), motion away from equilibrium (1–3) and motion towards equilibrium (2–4). Performance is assessed by evaluating reduction factors (RFs) from an uncontrolled structure for maximum displacement (Sd) total base-shear (Fb), and maximum acceleration (Sa) which assess performance in mitigating response damage, a risk of foundation damage and contents damage respectively. Spectra are created using 20 design level earthquakes from the medium suite of the SAC project with equal probability of occurrence and structural periods of T = 0.1–0.5 s. The RF spectra results are presented as median (50th) and 5th, 25th, 75th, and 95th percentile RF to define the distribution and change in risk across the 20 events. Statistical summaries of the results indicate that a 2–4 control method reduces the median value of Sd, Fb and Sa by approximately 10–40%, over all periods up to 5.0 s. These results are consistent over the 5–95th percentile range of all responses for a given period. The other control laws (1–3, 1–4) reduce Sd as much or more, but at a cost of increased base-shear (Fb) in comparison to the uncontrolled state. Overall, the reduction in terms of both displacement and base-shear demand is only available with the semi-active 2–4 control method. Finally, analytical expressions for the median displacement reduction factor are presented and compared to current Eurocode standards for comparison. These results indicate the robustness of simple semi-active viscous dampers could be better managed to mitigate response to the structure, foundation and risk.

Energy-efficient coding for electromagnetic nanonetworks in the Terahertz band

Wireless nanosensor networks (WNSNs) consist of numerous sensors with a nanoscale size and have many applications, such as the Internet of Nano-Things. The energy storage capacity of nanosensors is very limited; thus, energy efficiency has become an important issue in WNSNs. In this study, we investigate energy-efficient coding strategies and an energy consumption model for WNSNs. First, to map source words with equal probability of occurrence into different longer codewords, the average codeword weight minimization coding is presented. An energy consumption model based on energy consumption analysis is then proposed for WNSNs by jointly accounting for the energy consumption of both sender and receiver. Finally, the performance of the proposed coding scheme and energy consumption model is numerically and analytically investigated. Results show that the proposed coding is a promising scheme for WNSNs with a relatively low bit error rate.

Stochastic approach to analyzing the uncertainties and possible changes in the availability of water in the future based on scenarios of climate change

Abstract. The objective of this study was to analyze the changes and uncertainties related to water availability in the future (for the purposes of this study, the period between 2011 and 2040 was adopted), using a stochastic approach, taking as reference a climate projection from climate model Eta CPTEC/HadCM3. The study was applied to the Ijuí River basin in the south of Brazil. The set of methods adopted involved, among others, correcting the climatic variables projected for the future, hydrological simulation using artificial neural networks (ANNs) to define a number of monthly flows and stochastic modeling to generate 1000 hydrological series with equal probability of occurrence. A multiplicative type stochastic model was developed in which monthly flow is the result of the product of four components: (i) long-term trend component; (ii) cyclic or seasonal component; (iii) time-dependency component; and (iv) random component. In general, the results showed a trend to increased flows. The mean flow for a long period, for instance, presented an alteration from 141.6 m3 s−1 (1961–1990) to 200.3 m3 s−1 (2011–2040). An increment in mean flow and in the monthly standard deviation was also observed between the months of January and October. Between the months of February and June, the percentage of mean monthly flow increase was more marked, surpassing the 100 % index. Considering the confidence intervals in the flow estimates for the future, it can be concluded that there is a tendency to increase the hydrological variability during the period between 2011 and 2040, which indicates the possibility of occurrence of time series with more marked periods of droughts and floods.

Simultaneous buckling and fundamental frequency optimization of frames under uncertain loadings

This work presents the optimization of a frame under uncertain loadings when two design criteria are taken simultaneously into account. The uncertainty relates to the applied loading and is inherent to the operation of structures since real structures are designed to sustain a large variety of load cases of practical relevance. The design criteria considered are two of the most important from a practical point of view: buckling load and natural frequency. The technique developed is based in convex modeling where a load space is defined and all the elements of that load space have equal probability of occurrence. The outcome of the technique is an optimal design for which one loading or several loadings of the load space are the most dangerous or harmful to the structure. On the other hand, it is guaranteed that all the other loadings contained in the load space are conservative in the sense that they are less harmful to the optimal design.

Preattentive Memory-Based Comparison of Sound Intensity

Changes in the intensity of repeated, ignored sounds elicit the mismatch negativity (MMN) brain response which reflects preattentive detection of the change. It is generally assumed that the MMN in response to intensity changes reflects a memory-based comparison mechanism rather than being due to differential states of refractoriness of intensity-specific cortical neurons. In the present study, an experimental protocol consisting of 4 oddball blocks and 1 control block was used in order to separate memory-comparison-related effects from refractoriness-related ones. This design allowed an assessment of intensity MMN using physically identical stimuli with equal probability of occurrence in separate blocks, while avoiding contamination by refractoriness. Results were consistent with an MMN in response to intensity change that reflects genuine memory-based comparison.

Phylogenetic analysis of the distribution of chromosomal races of Mus musculus domesticus Rutty in Europe

Robertsonian (Rb) translocation is a common chromosomal rearrangement in the house mouse. In free-living populations, 79 fusions with different combinations of chromosomes 1 to 18 have been found in some 45 populations. An updated list of these fusions is presented and analysed in order to reveal the possible processes by which the fusions spread within or among populations. A widespread hypothesis is that when two populations share the same fusion, it can be assumed that they have a common ancestor. This can serve as the basis for the use of the cladistic methods. While I present such an analysis on the updated list of Rbs, I also point to the problems associated with it in this case because many fusions have multiple origins and exchanges of Rbs between populations are frequent. I have tried to use a different approach, based on a critical and quantitative evaluation of the hypothesis of common ancestry. Assuming that the 153 possible fusions have an equal probability of occurrence, I give the formula to compute the probability that populations share a given number of fusions by chance alone. Only when this probability is lower than a chosen level (say 5%) can the populations be inferred to have a non-independent origin (i.e. they have a common ancestor or they have exchanged chromosomes by introgression). This probability measure is then used as a distance estimate to show the relationship between all the Rb populations. This analysis suggests that although some Rbs must have occurred more than once, most of the populations have non-independent origins. Almost all the populations from northern Africa to Belgium and Germany appear to have close karyotopic relationships and form a major group. Clearly independent Rb populations are mainly found in the periphery of this major group, for example in Scotland, Denmark and Spain. ‘Chromosomal’ flow between Rb populations appears to be a very important process.

Home Range: A Weighted Normal Estimate and Tests of Underlying Assumptions

A robust estimation procedure is proposed to identify and reduce the influence of extreme locations for the bivariate normal home-range method. Tests are proposed for validating the underlying probability distribution from observed animal locations. Location data from a black bear (Ursus americanus) are used to demonstrate the effect of outliers on size and orientation of home-range estimates and to illustrate the goodness-of-fit tests. J. WILDL. MANAGE. 49(2):513-519 Burt (1943:351) defined the home range as area traversed by the individual in its normal activities of food gathering, mating, and caring for young. He believed that occasional sallies and exploratory moves outside the area should not be included as part of the home range. However, a lack of standard conventions for identifying such extreme locations has resulted in potentially arbitrary home-range estimates (Schoener 1981). Hayne (1949) recognized that biological understanding of an animal's home range required information about the intensity of use within the area. Furthermore, he believed that knowledge of the use pattern was important to define the limit of the home range. This pattern of use has subsequently been termed the utilization distribution or UD (Jennrich and Turner 1969, Van Winkle 1975, Anderson 1982). When the observed UD matches a simple probability distribution, we can readily obtain estimates of home-range size, shape, and orientation. These parameters provide a basis for important behavioral and ecological interpretations. Three commonly used methods to estimate home range are the minimum convex polygon, circular bivariate normal, and general bivariate normal methods. These approaches and their underlying probability distributions are discussed by Metzgar (1973); their biological assumptions, sample size biases, and sensitivity to extreme locations have been criticized by several authors (Jennrich and Turner 1969, Dixon and Chapman 1980, MacDonald et al. 1980, Schoener 1981, Anderson 1982). Typically, home-range methods are applied without evaluating the fit of the assumed probability distribution to the observed data. The method selected seems to be based on tradition rather than underlying properties of the data. I this paper we describe a robust estimator t minimize the problems of outliers for the general bivariate normal method and propose procedures for testing the goodness-of-fit of the assumed probability distributions. Location data from a black bear are used to illustrate the good ess-of-fit test and to demonstrate the effect of outliers on size and orientation for bivariate normal and minimum convex polygon home ranges. We wish to thank R. K. Steinhorst for valuable assistance during the development of the statistical methods. Data for our example were provided by J. Unsworth and the Idaho Dep. of Fish and Game. L. J. Nelson, D. F. Stauffer, and D. H. Johnson provided comments on the manuscript. Computer time for this project was provided by the Computing Cent., Univ. of Idaho. This is Contrib. No. 270 from the For., Wildl. and Range Exp. Stn., Univ. of Idaho. This content downloaded from 157.55.39.132 on Thu, 15 Sep 2016 04:56:52 UTC All use subject to http://about.jstor.org/terms 514 HOME RANGE * Samuel and Garton J. Wildl. Manage. 49(2):1985 UNIFORM DISTRIBUTION Metzgar (1973) described the frequency distribution of locations for an animal with equal probability of occurrence per unit of area throughout its home range. This bivariate uniform distribution assumes that the animal has no area of highest activity (center of activity), although an arithmetic center exists. A uniform UD may be appropriate for animals that perceive the environment in a fine-grained fashion (Schoener 1981), whose home ranges are uniform, and that lack a center of activity. The minimum convex polygon (MCP) appears to be an appropriate method to represent the homerange boundary of a uniform UD. The MCP method defines a distinct boundary as Metzgar (1973) suggested for the uniform UD, and Stickel (1954) found that home ranges of uniform use were accurately represented by similar polygon methods. However, because the MCP method does not consider the distribution of use within the home range (Macdonald et al. 1980, Voigt and Tinline 1980), the calculation of potential interaction measures (Macdonald et al. 1980, Voigt and Tinline 1980) by proportional home-range overlap (Owings et al. 1977, Nelson and Mech 1981, Seegmiller and Ohmart 1981) assumes an underlying uniform use pattern and may produce dramatically different values from that of a bivariate normal (Macdonald et al. 1980).

Dynamics of Hierarchy Formation: the Sequential Development of Dominance Relationships

A method for investigating the behavioral sequences used in forming dominance hierarchies is presented. There are four possible sequences for the formation of the first two dominance relationships in groups of three individuals (triads). Designating the winner in the first relationship formed as the initial dominant, the loser as the initial subordinate, and the animal not involved as the bystander, the four possible sequences are: (1) the initial dominants goes on to dominate the bystander (Double Dominance), (2) the bystander later dominates the initial subordinate (Double Subordinance), (3) the bystander later dominates the initial dominant (Bystander Dominates Initial Dominant), and (4) the initial subordinate later dominates the bystander (Initial Subordinate Dominates Bystander). Although each sequence has an equal probability of occurrence if dominance relationships are formed randomly, two of the sequences have different implications for the formation of the empirically common linear and near linear hierarchies than the other two. Linear and near linear hierarchies are, by definition, composed of all or nearly all triads with transitive dominance relationships (A dominates B, B dominates C, and A dominates C), while hierarchies far from linearity have many triads with intransitive relationships (A dominates B, B dominates C, and C dominates A). Double Dominance and Double Subordinance sequences guarantee the formation of triads with transitive dominance relationships, but the other two sequences can give triads with either transitive or intransitive relationships. Linear and near lincar hierarchies are ensured, therefore, by a preponderance of Double Dominance and Double Subordinance sequences in the component triads of larger groups. In an application of the method developed, sequences of dominance relationships formed in groups of three and four chickens were analyzed. In both experiments Double Dominance and Double Subordinance composed the overwhelming majority of all sequences - 91 % in triads and 87 % in tetrads. A further set of results indicated that intransitive relationships were common in constructed triads where chickens met only as component pairs and not in real triads where all three met together at the same time. These results suggest that hierarchy formation can be best viewed as a developmental process where preceding dominance interactions influence succeeding ones. This view was characterized as the jigsaw puzzle model of hierarchy formation, and it was contrasted with the more classical approach of explaining hierarchy structures by differences in the individual characteristics of group members. Many species beside chickens form linear and near linear hierarchies, and it was hypothesized that Double Dominance and Double Subordinance sequences also compose the majority of sequence occurrences in many of these species. The data available for other species were reviewed and offered tentative support for the hypothesis.

Some relationships between speech production and perception.

EMG studies of the American English vowel pairs /i-I/ and /e-epsilon/ reveal two different production strategies: some speakers appear to differentiate the members of each pair primarily on the basis to tongue height; for others the basis of differentiation appears to be tongue tension. There was no obvious reflection of these differences in the speech wave-forms or formant patterns of the two groups. To determine if these differences in production might correspond to differences in perception, two vowel identification tests were given to the EMG subjects. Subjects were asked to label the members of a seven-step vowel continuum, /i/ through /I/. In one condition each item had an equal probability of occurrence. The other condition was an anchoring test; the first stimulus, /i/, was heard four times as often as any other stimulus. Compared with the equal-probability test labelling boundary, the boundary in the anchoring test was displaced toward the more frequently occurring stimulus. The magnitude of the shift of the labelling boundary was greater for subjects using a production strategy based on tongue height than for subjects using tongue tension to differentiate these vowels, suggesting that the stimuli represent adjacent categories in the speakers' phonetic space for the former, but not for the latter, group.

ON THE INABILITY OF INTERVAL TIME SAMPLING TO REFLECT FREQUENCY OF OCCURRENCE DATA1

Interval time sampling yields the result, percentage of intervals scored. It is rudimentary to note that this measure per se does not constitute a response dimension. It is a useful behavioral measure, therefore, only to the extent that it accurately reflects the nature and degree of the fundamental dimensions from which it is drawn i.e., frequency and duration. The correspondence between scored intervals and response duration is fairly well understood (Journal of Applied Behavior Analysis, 1975, 8, 463–469; 1977, 10, 325–332). This study determined the correspondence between scored intervals and response frequency. Eleven, 30‐minute experimental sessions that differed along the variables of frequency of occurrence and time per response (the average length of a response per session) were computer simulated. In the first group of four sessions, the frequencies were 45, 100, 150, and 300; in these sessions, all responses ranged from one to three seconds. In the second group of four sessions, the frequencies were 31, 61, 101, and 152; in these sessions, all responses ranged from three to nine seconds. In the last group of three sessions, the frequencies were 25, 34, and 50; here, all responses ranged from nine to 27 seconds. The response distribution within the above ranges was rectangular, with each whole second represented once. The responses were selected by a random number generator, and on each trial every number in the distribution had an equal probability of occurrence. These provisions produced a linear pattern of responding. The time per response in the three groups of sessions were 2, 6, and 18 seconds. For all sessions, event recordings were made and analyzed. The analysis consisted of using partial interval time sampling to determine the percentage of intervals scored; this total was subdivided into intervals containing (1) single responses, (2) multiple responses, (3) continuing responses, and (4) response initiations or terminations. The analysis was performed when the length of the observation interval was 5, 10, 20, 30, 60, and 120 seconds. An additional session drawn from a study that contained real‐life data was subjected to this same analysis. The most significant results were derived by finding the ratio of scored intervals containing single responses to the total intervals scored. If every scored interval contained a single response, this ratio would equal 1.0; if no scored interval contained a single response, the ratio would be 0.0. It can be seen that this ratio is an objective expression of the validity of interval time sampling as a measure of response frequency. Of 66 data points (11 sessions × six observation lengths per session), only five were equal to or greater than 0.80. These five points were all found in just two sessions (f = 45, 100). A validity index of less than 0.50 was observed in 49 of the 66 points. Also, the validity index increased, peaked, and then decreased within sessions as the length of the observation interval was increased. The results from the real‐life session were in close agreement with those obtained from the simulations. The importance of these and previous findings lies in the demonstration that changes in scored intervals need not represent true behavior change. The data indicate that there are many combinations of behavioral frequency and duration where interval time sampling cannot produce valid measurement results.

Some relationships between articulation and perception

EMG studies of the American English vowel pairs /i‐ɪ/ and /e‐ε/ reveal two different production strategies: some speakers appear to differentiate the members of each pair primarily on the basis of tongue height; for others the basis of differentiation appears to be tongue tension. To determine if these production differences correspond to perception differences, two vowel identification tests were given to the EMG subjects. Subjects were asked to label the members of a seven‐step vowel continuum, /i/ through /ɪ/. In one test each item had an equal probability of occurrence. The other was an anchoring test: the first stimulus, /i/, was heard four times as often as any other. Compared with the equal‐probability test labelling boundary, the boundary in the unequal‐probability test was displaced toward the anchor stimulus. However, the magnitude of the shift was greater for subjects using a production strategy based on tongue height than for subjects using tongue tension to differentiate the vowels. [This work was supported by NIH Grants NS‐13617, NS‐05332, HD‐01994, and RR‐05596 to Haskins Laboratories; and SUNY Research Foundation.]

MODIFIED POISSON PROBABILITY LAW FOR POINT PATTERN MORE REGULAR THAN RANDOM1

MAPPING, and using map evidence, for incisive, descriptive statements about spatial distributions is a fundamental operation in geographic research. In terms of their abstract properties, map distributions exist in one of the three lowest geometric dimensions -the use of points, lines, and areas to represent a distribution. Map analysis is the description of the density and pattern of this geometry. The map itself may serve as the descriptive statement, or the many subtleties of map distributions may be summarized into symbols, words, or numbers. Highly regular or obviously systematic patterns are found infrequently in geographic investigations. Usually, the patterns display no obvious order or system. In interpreting such patterns, there is a temptation to dismiss analysis with the statement that the distribution is irregular or, possibly, to say that it is a distribution. To say that a distribution is irregular neither effectively describes it nor suggests cause. To say that a distribution is random, in a nontechnical sense, is to say that the pattern has no discernible order and that cause is undeterminable. In the terminology of mathematical statistics, the term random has a precise meaning which refers to the process generating a pattern and the pattern is the realization of a theoretical process. A process is synonymous with pure chance because each event has an equal probability of occurrence. In terms of a map pattern, pure chance means that each map location has an equal probability of receiving a symbol. Since it is highly unlikely that geographic distributions, particularly locational patterns involving human decisions, are the result of equally probable events, it is expected that most map patterns reflect some system or order. It is for this reason that map patterns are examined for evidence of a spatial process. The search for