62,168 research outputs found
The New White Flight
White charter school enclaves—defined as charter schools located in school districts that are thirty percent or less white, but that enroll a student body that is fifty percent or greater white— are emerging across the country. The emergence of white charter school enclaves is the result of a sobering and ugly truth: when given a choice, white parents as a collective tend to choose racially segregated, predominately white schools. Empirical research supports this claim. Empirical research also demonstrates that white parents as a collective will make that choice even when presented with the option of a more racially diverse school that is of good academic quality.
Despite the connection between collective white parental choice and school segregation, greater choice continues to be injected into the school assignment process. School choice assignment policies, particularly charter schools, are proliferating at a substantial rate. As a result, parental choice rather than systemic design is creating new patterns of racial segregation and inequality in public schools. Yet the Supreme Court’s school desegregation jurisprudence insulates racial segregation in schools ostensibly caused by parental choice rather than systemic design from regulation. Consequently, the new patterns of racial segregation in public schools caused by collective white parental choice largely escapes regulation by courts.
This article argues that the time has come to reconsider the legal and normative viability of regulating racial segregation in public schools caused by collective white parental choice. The article makes two important contributions to the legal literature on school desegregation. First, using white charter school enclaves as an example, it documents the ways in which school choice policies are being used to allow whites as a collective to satisfy their preference for segregated predominately white schools. Second, the article sets forth both constitutional and normative arguments for regulating the private choices that result in stark racial segregation patterns in public schools
Improving Message Delivery Performance in Opportunistic Networks using a Forced-stop diffusion scheme
The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-40509-4_11The performance of mobile opportunistic networks strongly depends on contact duration. If the contact lasts less than the required transmission times, some messages will not get delivered, and the whole diffusion scheme will be seriously affected.
In this paper we propose a new diffusion method, called Forced-Stop, that is based on controlling node mobility to guarantee a complete message transfer. Using the ONE simulator and realistic mobility traces, we compared our proposal with the classical Epidemic diffusion.
We show that Forced-Stop improves the message delivery performance, increasing the delivery ratio up to 30\%, and reducing the latency of message delivery up to 40\%, with a limited impact on buffer utilisation and message relaying.
These results can be a relevant indication to the designers of opportunistic network applications that could integrate in their products strategies to inform the user about the need to temporarily stop in order to favor the overall data delivery.This work was partially supported by the Ministerio de EconomĂa y Competitividad, Programa Estatal de InvestigaciĂłn, Desarrollo e InnovaciĂłn Orientada a los Retos de la Sociedad, Proyectos I+D+I 2014, Spain, under Grant TEC2014-52690-R, the Generalitat Valenciana, Spain, under Grant AICO/2015/108, the SecretarĂa Nacional de EducaciĂłn Superior, Ciencia, TecnologĂa e InnovaciĂłn del Ecuador(SENESCYT), and the Universidad Laica Eloy Alfaro de Manabi, Ecuador.Herrera Tapia, J.; Hernández Orallo, E.; Tomás DomĂnguez, AE.; Manzoni, P.; Tavares De Araujo Cesariny Calafate, CM.; Cano Escribá, JC. (2016). Improving Message Delivery Performance in Opportunistic Networks using a Forced-stop diffusion scheme. En Ad-hoc, Mobile, and Wireless Networks. Springer. 156-168. https://doi.org/10.1007/978-3-319-40509-4_11S156168Pelusi, L., Passarella, A., Conti, M.: Opportunistic networking: data forwarding in disconnected mobile ad hoc networks. IEEE Commun. Mag. 44(11), 134–141 (2006)Ferretti, S.: Shaping opportunistic networks. Comput. Commun. 36, 481–503 (2013)Keränen, A., Ott, J., Kärkkäinen, T.: The ONE simulator for DTN protocol evaluation. In: Proceedings of the Second International ICST Conference on Simulation Tools and Techniques, Rome (2009)Tsai, T.-C., Chan, H.-H.: NCCU Trace: social-network-aware mobility trace. IEEE Commun. Mag. 53, 144–149 (2015)AnAverage WhatsApp User Sends Messages per Month, 15 September 2015. http://www.statista.com/chart/1938/monthly-whatsapp-usage-per-userNiu, J., Guo, J., Cai, Q., Sadeh, N., Guo, S.: predict and spread: an efficient routing algorithm for opportunistic networking. In: Wireless Communications and Networking Conference (WCNC), 2011 IEEE, pp. 498–503, CancĂşn (2011)Thakur, G.S., Kumar, U., Helmy, A., Hsu, W.-J.: On the efficacy of mobility modeling for DTN evaluation: analysis of encounter statistics andspatio-temporal preferences. In: 7th International Wireless Communications and Mobile Computing Conference (IWCMC), pp. 510–515, Istanbul (2011)Warthman, F.: Delay-and Disruption-Tolerant Networks (DTNs) a tutorial, version 2.0. In: The InterPlaNetary (IPN) Internet Project. InterPlanetary Networking Special Interest Group (IPNSIG) (2012)Battestini, A., Setlur, V., Sohn, T.: A large scale study of text messaging use. In: 12th International Conference on Human Computer Interaction with Mobile Devices and Services MobileHCI, pp. 1–10, Lisbon (2010)Förster, A., Garg, K., Nguyen, H.A., Giordano, S. On context awareness and social distance in human mobility traces. 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In: Sixth IEEE Workshop on Mobile Computing Systems and Applications (WMCSA 2004), Low Wood (2004)Feng, Z., Chin, K.-W.: A unified study of epidemic routing protocols and their enhancements. In: IEEE 26th International Parallel and Distributed Processing Symposium Workshops PhD Forum (IPDPSW), pp. 1484–1493, Shanghai (2012)Vardalis, D., Tsaoussidis, V.: Exploiting the potential of DTN for energy-efficient internetworking. J. Syst. Softw. 90, 91–103 (2014)Rango, F.D., Amelio, S., Fazio, P.: Epidemic strategies in delay tolerant networks from an energetic point of view: main issues and performance evaluation. J. Networks 10(01), 4–14 (2015)Herrera-Tapia, J., Manzoni, P., Hernández-Orallo, E., Calafate, C.T., Cano, J.-C.: Power consumption evaluation in vehicular opportunistic networks. In: IEEE 12th CCNC 2015 Workshops - VENITS, pp. 925–930, Las Vegas (2015)Erramilli, V., Crovella, M.: Forwarding in opportunistic networks with resource constraints. In: Proceedings of the third ACM workshop on Challenged networks - CHANTS 2008, pp. 41–47, San Francisco (2008)Fathima, G., Wahidabanu, R.: Buffer management for preferential delivery in opportunistic delay tolerant networks. Int. J. Wirel. Mob. Netw. (IJWMN) 3, 15–28 (2011)Pan, D., Ruan, Z., Zhou, N., Liu, X., Song, Z.: A comprehensive-integrated buffer management strategy for opportunistic networks. EURASIP J. Wirel. Commun. Netw. 2013(1), 1–10 (2013)Hernández-Orallo, E., Herrera-Tapia, J., Cano, J.-C., Calafate, C.T., Manzoni, P.: Evaluating the impact of data transfer time in contact-based messaging applications. IEEE Commun. Lett. 19, 1814–1817 (2015)de Abreu, C.S., Salles, R.M.: Modeling message diffusion in epidemical DTN. Ad Hoc Netw. 16, 197–209 (2014
Robotic Wireless Sensor Networks
In this chapter, we present a literature survey of an emerging, cutting-edge,
and multi-disciplinary field of research at the intersection of Robotics and
Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor
Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system
that aims to achieve certain sensing goals while meeting and maintaining
certain communication performance requirements, through cooperative control,
learning and adaptation. While both of the component areas, i.e., Robotics and
WSN, are very well-known and well-explored, there exist a whole set of new
opportunities and research directions at the intersection of these two fields
which are relatively or even completely unexplored. One such example would be
the use of a set of robotic routers to set up a temporary communication path
between a sender and a receiver that uses the controlled mobility to the
advantage of packet routing. We find that there exist only a limited number of
articles to be directly categorized as RWSN related works whereas there exist a
range of articles in the robotics and the WSN literature that are also relevant
to this new field of research. To connect the dots, we first identify the core
problems and research trends related to RWSN such as connectivity,
localization, routing, and robust flow of information. Next, we classify the
existing research on RWSN as well as the relevant state-of-the-arts from
robotics and WSN community according to the problems and trends identified in
the first step. Lastly, we analyze what is missing in the existing literature,
and identify topics that require more research attention in the future
Recommended from our members
Multimedia delivery in the future internet
The term “Networked Media” implies that all kinds of media including text, image, 3D graphics, audio
and video are produced, distributed, shared, managed and consumed on-line through various networks,
like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white
paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked
challenges of the Networked Media in the transition to the Future of the Internet.
Internet has evolved and changed the way we work and live. End users of the Internet have been confronted
with a bewildering range of media, services and applications and of technological innovations concerning
media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace
of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more
than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so
regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected
to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising
to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged
that in a near- to mid-term future, the Internet will provide the means to share and distribute (new)
multimedia content and services with superior quality and striking flexibility, in a trusted and personalized
way, improving citizens’ quality of life, working conditions, edutainment and safety.
In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe
network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as
community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of
interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and
innovative applications “on the move”, like virtual collaboration environments, personalised services/
media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content
combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P
networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to
contribute towards such a vision.
Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6)
and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily
contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way
ahead in the area of Content Aware media delivery platforms
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