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The purpose of this paper is to describe a multi‐robot solution to the problem of chemical source localization, in which a team of inexpensive, simple vehicles with short‐range, low‐power sensing, communication, and processing capabilities trace a chemical plume to its source emitter

The source localization problem is analyzed using computational fluid dynamics simulations of airborne chemical plumes. The analysis is divided into two parts consisting of two large experiments each: the first part focuses on the issues of collaborative control, and the second part demonstrates how task performance is affected by the number of collaborating robots. Each experiment tests a key aspect of the problem, e.g. effects of obstacles, and defines performance metrics that help capture important characteristics of each solution.

The new empirical simulations confirmed previous theoretical predictions: a physics‐based approach is more effective than the biologically inspired methods in meeting the objectives of the plume‐tracing mission. This gain in performance is consistent across a variety of plume and environmental conditions. This work shows that high success rate can be achieved by robots using strictly local information and a fully decentralized, fault‐tolerant, and reactive control algorithm.

This is the first paper to compare a physics‐based approach against the leading alternatives for chemical plume tracing under a wide variety of fluid conditions and performance metrics. This is also the first presentation of the algorithms showing the specific mechanisms employed to achieve superior performance, including the underlying fluid and other physics principles and their numerical implementation, and the mechanisms that allow the practitioner to duplicate the outstanding performance of this approach under conditions of many robots navigating through obstacle‐dense environments.

In light of the current international concerns with security and terrorism, interest is increasing on the topic of using robot swarms to locate the source of chemical hazards. The purpose of this paper is to place this task, called chemical plume tracing (CPT), in the context of fluid dynamics.

This paper provides a foundation for CPT based on the physics of fluid dynamics. The theoretical approach is founded upon source localization using the divergence theorem of vector calculus, and the fundamental underlying notion of the divergence of the chemical mass flux. A CPT algorithm called fluxotaxis is presented that follows the gradient of this mass flux to locate a chemical source emitter.

Theoretical results are presented confirming that fluxotaxis will guide a robot swarm toward chemical sources, and away from misleading chemical sinks. Complementary empirical results demonstrate that in simulation, a swarm of fluxotaxis‐guided mobile robots rapidly converges on a source emitter despite obstacles, realistic vehicle constraints, and flow regimes ranging from laminar to turbulent. Fluxotaxis outperforms the two leading competitors, and the theoretical results are confirmed experimentally. Furthermore, initial experiments on real robots show promise for CPT in relatively uncontrolled indoor environments.

A physics‐based approach is shown to be a viable alternative to existing mainly biomimetic approaches to CPT. It has the advantage of being analyzable using standard physics analysis methods.

The fluxotaxis algorithm for CPT is shown to be “correct” in the sense that it is guaranteed to point toward a true source emitter and not be fooled by fluid sinks. It is experimentally (in simulation), and in one case also theoretically, shown to be superior to its leading competitors at finding a source emitter in a wide variety of challenging realistic environments.

Social entrepreneurs engage in collective action to adapt and solve social problems in complex environments. Through collective action, they mobilise and access resources to create positive social change in local communities. While previous studies explain the role of social identity in promoting cooperation, this paper aims to examine shared meaning as a predictor of collective action in social entrepreneurial ventures (SEVs). This study was conducted among founders of SEVs focusing on their engagement in collective action.

The study adopted a cross-sectional survey to achieve its objectives. The population comprised 558 SEVs registered with the Kampala Capital City Authority in Uganda. A sample size of 226 social ventures was determined using Krecjie and Morgan and participants were selected using the simple random sampling technique. The questionnaires were distributed by two research assistants, and 210 completed questionnaires were returned. Structural equation modelling was used to analyse survey data and test the study hypotheses.

The study findings show that shared meaning in the form of teamwork and group efficacy predict collective action in SEVs.

The results have implications for social entrepreneurship researchers, practitioners and policymakers. Firstly, creating social ties by belonging to different groups in the community creates common understanding among social entrepreneurs and other actors fostering cooperation to solve problems in the local community. Secondly, understanding each other’s perspective well enough facilitates a shared view of social problems for combined action.

SEVs should provide relevant information using the right channels in local communities to promote collaboration. Failure to use the right communication channels may prevent collective action. Managers in social ventures should allow for open information sharing between themselves and the partners that they work with to address social problems. This enables them to share both the good and bad feedback. It also enables the growth of teams and improves how they work. The teams should be developed with specific responsibilities so that everyone is clear on what they should do while addressing social problems.

The researchers argue that shared meaning develops when social entrepreneurs interact with the local community and other stakeholders prompting joint action to address social problems. This study extends knowledge on collective action using the activity domain theory.

Aarhus Kommunes Biblioteker (Teknisk Bibliotek), Ingerslevs Plads 7, Aarhus, Denmark. Representative: V. NEDERGAARD PEDERSEN (Librarian).

This study analyses how media choices can be used in the construction of social identity.

We approach the topic through the analytical lens of identity work. We present a case study of a community of IT students during their first year of studies, including participant observation, focus groups, and surveys. We focus on what community means to the individuals located within a specific social context. This allows us to examine ICT use and adoption holistically as a key aspect of community formation and identity maintenance.

We depict everyday interactions in which the choice of an older information communication technology, Internet Relay Chat, serves participants in their quest for social belongingness in their community and in distinguishing the community positively from other social groups. This chapter describes how identity work is accomplished by adopting and valuing shared, social views about users versus non-users, including: (1) emphasizing the skills and efforts needed for using Internet Relay Chat (IRC), (2) undermining the use of other technologies, and (3) deploying and referencing IRC jargon and “insider humor” within the broader community.

By examining online and offline social interactions in a defined community over time, we expose the process of identity work in a holistic manner. Our analysis emphasizes the underlying process where media choices can be harnessed to fulfill the need to identify with groups and feel affirmed in one’s claims to both personal and social identity.

Human presence tends to decrease biodiversity and often results in the local extinction or even global extinction of megafauna. The focus here is on how humans have affected wolf populations in what are now known as the contiguous 48 United States. While the arrival of indigenous peoples to the region produced the extinction of some species and a reduction in wolf populations, the cultural values and economic system, i.e., capitalism, utilized by the European invaders led to anthropogenic decimation of wildlife species on an unprecedented scale and the near local extinction of wolves. Although capitalism almost led to the local extinction of wolves in the contiguous 48 US states, it also produced an educated, affluent urban class concerned with protecting endangered species. Unlike farmers and ranchers, this urbanized class does not view wildlife as a potential economic threat. The vast majority of contemporary Americans, i.e., 96%, do not engage in sport hunting, so most do not view apex predators as unwanted competitors for game species. Moreover, many individuals who belong to the urban affluent class, even those who do not engage in wildlife viewing or other forms of outdoor recreation, value biodiversity. Since the late twentieth century, this has resulted in the preservation of existing wolf populations and reintroducing wolves to some of their historical ranges. These trends are likely to continue in the coming decades. However, capitalism should not be viewed as a system that initially decimated wolf populations and eventually created an economic class that saved them. It is argued that, due to its growth imperative, if left unchecked, capitalism will ultimately destroy wolves and many other species that have been granted temporary reprieves from extinction.

IT is evident from the numerous press cuttings which are reaching us, that we are once more afflicted with one of those periodical visitations of antagonism to Public Libraries, which occasionally assume epidemic form as the result of a succession of library opening ceremonies, or a rush of Carnegie gifts. Let a new library building be opened, or an old one celebrate its jubilee, or let Lord Avebury regale us with his statistics of crime‐diminution and Public Libraries, and immediately we have the same old, never‐ending flood of articles, papers and speeches to prove that Public Libraries are not what their original promoters intended, and that they simply exist for the purpose of circulating American “Penny Bloods.” We have had this same chorus, with variations, at regular intervals during the past twenty years, and it is amazing to find old‐established newspapers, and gentlemen of wide reading and knowledge, treating the theme as a novelty. One of the latest gladiators to enter the arena against Public Libraries, is Mr. J. Churton Collins, who contributes a forcible and able article, on “Free Libraries, their Functions and Opportunities,” to the Nineteenth Century for June, 1903. Were we not assured by its benevolent tone that Mr. Collins seeks only the betterment of Public Libraries, we should be very much disposed to resent some of the conclusions at which he has arrived, by accepting erroneous and misleading information. As a matter of fact, we heartily endorse most of Mr. Collins' ideas, though on very different grounds, and feel delighted to find in him an able exponent of what we have striven for five years to establish, namely, that Public Libraries will never be improved till they are better financed and better staffed.

The great magnitude differences between the integral tunnel and its structure details make it impossible to numerically model and analyze the global and local seismic behavior of large-scale shield tunnels using a unified spatial scale, even with the help of supercomputers. The paper aims to present a combined equivalent & multi-scale simulation method, by which the tunnel's major mechanical properties under seismic loads can be represented by the equivalent model, and the seismic responses of the interested details can be studied efficiently by the coupled multi-scale model.

The nominal orthotropic material constants of the equivalent tunnel model are inversely determined by fitting the modal characteristics of the equivalent model with the corresponding segmental lining model. The critical sections are selected by comprehensive analyzing of the integral compression/extension and bending loads in the equivalent lining under the seismic shaking and the coupled multi-scale model containing the details of interest is solved by the mixed time explicit integration algorithm.

The combined equivalent & multi-scale simulation method is an effective and efficient way for seismic analyses of large-scale tunnels. The response of each flexible joint is related to its polar location on the lining ring, and the mixed time integration method can speed-up the calculation process for hybrid FE model with great differences in element sizes.

The orthotropic equivalent assumption is, to the best of the authors’ knowledge, for the first time, used in the 3D simulation of the shield tunnel lining, representing the rigidity discrepancies caused by the structural property.

The purpose of this paper is to examine the history of the Conferences on Historical Analysis & Research in Marketing (CHARM) from their inception in 1983 through 2007 focusing on the influence of Stanley C. Hollander, who co‐founded the CHARM conference and whose drive and determination fueled its growth for the first 20 years.

This study uses traditional historical narrative based on personal interviews, archival research, and content analysis of CHARM Proceedings.

The history of CHARM is described and Hollander's role in developing the conference is highlighted.

There is no written history of CHARM. This story is a major part of Hollander's legacy.