Amount Of Historical Information Research Articles

Bipartite containment of heterogeneous multi‐agent systems under denial‐of‐service attacks: A historical information‐based control scheme

AbstractA distributed control scheme based on historical information is designed to solve the problem of stable control of multi‐agent systems under denial of service (DoS) attacks in this article. It achieves the control objective of bipartite output containment control, that is, the output states of the followers smoothly enter the target area. The control scheme updates the states of followers through historical information in the control protocol when agents are subjected to DoS attacks. A distributed state observer with a storage module is designed to efficiently estimate the state of followers and store the observed information as history information. The historical information of control protocol calls is not necessarily the real state information in the existence of DoS attacks. Consequently, a closed‐loop feedback state compensator is designed. Then, the state compensator is converted from the time domain to the frequency domain for stability analysis using the Nyquist criterion. It is obtained that an upper bound on the amount of historical information can achieve the bipartite output trajectories containment of the controlled system. The output trajectories of the followers converge into two dynamic convex hulls, one of which is surrounded by multiple leaders, and the other is a convex hull with opposite signs of the leaders. Finally, a numerical simulation is used to verify the proposed control scheme, and the operability of the scheme is further demonstrated in a physical experiment.

Following the footsteps of giants: modeling the mobility of historically notable individuals using Wikipedia

The steady growth of digitized historical information is continuously stimulating new different approaches to the fields of Digital Humanities and Computational Social Science. In this work we use Natural Language Processing techniques to retrieve large amounts of historical information from Wikipedia. In particular, the pages of a set of historically notable individuals are processed to catch the locations and the date of people’s movements. This information is then structured in a geographical network of mobility patterns.We analyze the mobility of historically notable individuals from different perspectives to better understand the role of migrations and international collaborations in the context of innovation and cultural development. In this work, we first present some general characteristics of the dataset from a social and geographical perspective. Then, we build a spatial network of cities, and we model and quantify the tendency to explore of a set of people that can be considered as historically and culturally notable. In this framework, we show that by using a multilevel radiation model for human mobility, we are able to catch important features of migration’s behavior. Results show that the choice of the target migration place for historically and culturally relevant people is limited to a small number of locations and that it depends on the discipline a notable is interested in and on the number of opportunities she/he can find there.

Memory mechanism with weighting promotes cooperation in the evolutionary games

Abstract Memory normally plays an important role when investigating the collective behaviours in real world. Each rational player can get a more reasonable strategy by comprehensively considering certain amount of historical information within its memory scope. Motivated by the fact, we here propose a memory mechanism with weighting whose core lies in three aspects: (i) Each player applies a memory rule to compare its own historical accumulated payoffs inside the range of memory length and to take the maximal one and corresponding strategy as historical optimal accumulated payoff and historical optimal strategy; (ii) Each neighbour of a player is endowed with a weighting which is the ratio of historical optimal accumulated payoff of each neighbour to the total historical optimal accumulated payoff of all neighbours of the player; (iii) Each player interacts with a neighbour selected by probability equal to weighting, and then updates its historical optimal strategy according to Fermi function. The asynchronous updating algorithm is used to study the evolution of cooperation with different memory lengths on a regular lattice. Simulation results show that the proposed mechanism effectively promotes cooperation in three classical social dilemmas. Moreover, it is revealed that the cooperation level, by and large, increases first and then decreases as the memory length increases in the prisoner’s dilemma and snowdrift game, and that the cooperation level increases as so does the memory length in the stag-hunt game.

Memory-based conformity enhances cooperation in social dilemmas

The problem of how cooperative behaviors emerge in real world has been widely investigated and it is found that cooperative behaviors are closely related to memory, which means a rational player can get a more reasonable strategy by comprehensively considering certain amount of historical information within its memory scope. On the other hand, due to the potential risk during pursuing high payoff in human society, selecting the most common strategy for a player inside the interaction range is relatively safer, at least its payoff is not much lower than average, which is known as conformity. Motivated by these facts, we here propose a mechanism of conformity with memory whose core lies in two facts: (i) Each player first applies a memory rule to compare its own historical payoffs with a limited memory length and to take the strategy corresponding to the maximal payoff as historical optimal strategy; (ii) Each player can get the virtual optimal strategy by selecting the most common strategy from its neighbors’ historical optimal strategies according to the conformity rule. The asynchronous updating algorithm, together with the virtual strategy, is used to study the evolution of cooperation with different memory lengths on a regular lattice. Simulation results show that the proposed mechanism remarkably promotes cooperation in three classical evolutionary social dilemmas. More specifically, it is revealed that the cooperation level decreases gradually as the memory length increases in the prisoner’s dilemma and snowdrift game, and that the cooperation level increases as so does the memory length in the stag-hunt game.

On the decidability of population size histories from finite allele frequency spectra

Understanding the historical events that shaped current genomic diversity has applications in historical, biological, and medical research. However, the amount of historical information that can be inferred from genetic data is finite, which leads to an identifiability problem. For example, different historical processes can lead to identical distribution of allele frequencies. This identifiability issue casts a shadow of uncertainty over the results of any study which uses the frequency spectrum to infer past demography. It has been argued that imposing mild ‘reasonableness’ constraints on demographic histories can enable unique reconstruction, at least in an idealized setting where the length of the genome is nearly infinite. Here, we discuss this problem for finite sample size and genome length. Using the diffusion approximation, we obtain bounds on likelihood differences between similar demographic histories, and use them to construct pairs of very different reasonable histories that produce almost-identical frequency distributions. The finite-genome problem therefore remains poorly determined even among reasonable histories. Where fits to few-parameter models produce narrow parameter confidence intervals, large uncertainties lurk hidden by model assumption.

The grand challenges to air pollution

The grand challenges to air pollution

The Role of Prior Model Calibration on Predictions with Ensemble Kalman Filter

This paper, based on a real world case study (Limmat aquifer, Switzerland), compares inverse groundwater flow models calibrated with specified numbers of monitoring head locations. These models are updated in real time with the ensemble Kalman filter (EnKF) and the prediction improvement is assessed in relation to the amount of monitoring locations used for calibration and updating. The prediction errors of the models calibrated in transient state are smaller if the amount of monitoring locations used for the calibration is larger. For highly dynamic groundwater flow systems a transient calibration is recommended as a model calibrated in steady state can lead to worse results than a noncalibrated model with a well-chosen uniform conductivity. The model predictions can be improved further with the assimilation of new measurement data from on-line sensors with the EnKF. Within all the studied models the reduction of 1-day hydraulic head prediction error (in terms of mean absolute error [MAE]) with EnKF lies between 31% (assimilation of head data from 5 locations) and 72% (assimilation of head data from 85 locations). The largest prediction improvements are expected for models that were calibrated with only a limited amount of historical information. It is worthwhile to update the model even with few monitoring locations as it seems that the error reduction with EnKF decreases exponentially with the amount of monitoring locations used. These results prove the feasibility of data assimilation with EnKF also for a real world case and show that improved predictions of groundwater levels can be obtained.

Preaching History in a Social Studies Methods Course: A Portrait of Practice

This article presents a portrait of practice of one social studies methods professor engaged in teaching his course and analyzes the choices the professor makes during the semester. These choices are linked to his philosophy of social studies education with particular attention paid to his passionate belief in the American story as the core of elementary social studies education. Through interviews, extensive field notes collected during the semester, and a collection of all corresponding documents, a portrait of the social studies methods professor (Dr. Henry Merrill) emerges. Merrill uses Hirsch, Ravitch, and Hakim as the foundation on which he builds his methods course. He believes his preservice teachers are “knowledge conveyors” and therefore need to know large amounts of historical information in order to pass that information on to their students. However powerful or flawed we may view Merrill, the issue remains that the idea of “common practice” in social studies methods courses may not be too common.

Diatoms as indicators of wetland salinity in the Upper South East of South Australia

Wetland degradation in the Upper South East of South Australia is an urgent management concern. Scant recent environmental data is available for the region and long-term monitoring data is lacking. Usually a palaeoecological analysis is able to reveal environmental change in the medium-to long-term past. However, the region is not conducive to palaeoecological investigation due to a fluctuating upper groundwater aquifer and alkaline soils whiclh have destroyed most microfossils. It was found that the diatom assemblage was preserved in the wetlands of the region for the period of European settlement. Analysis of the diatom assemblage enabled production of an inferred salinity curve. In combination with a small amount of historical information that was available, the salinity trend for the wetlands, for the period of European agricultural activities, was identified. It was found that, while groundwater salinity has been increasing, the wetland areas have experienced a freshening of surface water. This is due to an increase of throughflow of surface water, a result of constructed drainage systems flushing salts from the wetlands. Despite the freshening of wetlands they continue to degrade due to the changed hydrology, an impact of the drainage structures.

WANDALÁA sources Politik zwischen den Zeilen: Arabische Handschriften der Wandalá in Nordkamerun. By HERMANN FORKL, with the co-operation of REINHARD WEIPERT. Berlin: Klaus Schwarz Verlag, 1995. Pp. 559. No price given (ISBN 3-87997-245-1).

The Wandalá community of northern Cameroon and adjoining portions of north-eastern Nigeria have a long tradition of state forms of government. In recent centuries, following conversion to Islam, they have composed an historiography in Arabic, an effort entailing the adaptation of alien characters to the names and titles of a language whose sound system differs considerably from the one for which the symbols were originally intended. Some individual examples of this literature have already been published, at least in translation, but with widely varying degrees of formality and precision. The volume reviewed here offers a critical edition and an accurate, persuasively annotated translation of all seventeen known Wandalá historical manuscripts in Arabic. Nine of the manuscripts are state chronicles that convey greater or lesser amounts of historical information arranged according to the remembered sequence of Wandalá monarchs. One composition is a dramatic patriotic epic, probably attributable to the days of the intrusive eastern warlord Rabih Fadl Allah at the dawn of the present century but couched in the form of a narrative of the defense of the Wandalá kingdom against an eighteenth-century invasion from Borno. Four documents are lists of local authorities at the south-eastern town of Mime. Two manuscripts list title officials of the central court together with some of their duties, while a third describes some of the tax obligations incumbent upon various groups of subjects.