1,733,490 research outputs found
Accumulated testimony: layering French girls' diaries on the Algerian exodus
Full text linkIn 1997, French-Algerian author Leïla Sebbar published an illustrated children’s book, J’étais enfant en Algérie, juin 1962 (‘I was a child in Algeria, June 1962’) in which she creates the fictional account of a young girl from the interior of Algeria leaving her home during the great exodus of the French just prior to Algerian independence. Using the genre of diary writing, Sebbar’s text reads as testimonial of fleeing their country for a homeland they do not know. Although this text is intimate, Sebbar relies on accumulated scraps of collective experience that, when joined to her own, fill in the absence of her homeland. In 2013, French artist Nicole Guiraud published her personal diaries kept before and during her exodus from Algeria from April to July 1962. Her raw representation of traumatic upheaval is couched in a rich paratext including artwork, photographs, and German translations, that simultaneously intensifies her account and distracts the reader from the extreme pain behind her words. In this article I demonstrate how fictional and real accounts published in very different historical contexts convey the exodus experienced by almost one million individuals and how each author deploys a layering technique to simultaneously draw in and distance the reader from extraordinarily painful personal experience
The energy problem in resource constrained wireless networks
Full text linkToday Wireless Sensor Networks are part of a wider scenario involving several wireless and wired communication technology: the Internet Of Things (IoT). The IoT envisions billions of tiny embedded devices, called Smart Objects, connected in a Internet-like structure. Even if the integration of WSNs into the IoT scenario is nowadays a reality, the main bottleneck of this technology is the energy consumption of sensor nodes, which quickly deplete the limited amount of energy of available in batteries. This drawback, referred to as the energy problem, was addressed in a number of research papers proposing various energy optimization approaches to extend sensor nodes lifetime. However, energy problem is still an open issue that prevents the full exploitation of WSN technology.
This thesis investigates the energy problem in WSNs and introduces original solutions trying to mitigate drawbacks related to this phenomenon. Starting from solutions proposed by the research community in WSNs, we deeply investigate critical and challenging factors concerning the energy problem and we came out with cutting-edge low-power hardware platforms, original software energy-aware protocols and novel energy-neutral hardware/software solutions overcoming the state-of-art.
Concerning low-power hardware, we introduce the MagoNode, a new WSN mote equipped with a radio frequency (RF) front-end which enhances radio performance. We show that in real applicative contexts, the advantages introduced by the RF front-end keep packet re-trasmissions and forwards low. Furthermore, we present the ultra low-power Wake-Up Radio (WUR) system we designed and the experimental activity to validate its performance. In particular, our Wake-up Radio Receiver (WRx) features a sensitivity of -50 dBm, has a current consumption of 579nA in idle-listening and features a maximum radio range of about 19 meters. What clearly resulted from the experimental activity is that performance of the WRx is strongly affected by noise. To mitigate the impact of noise on WUR communication we implemented a Forward Error Correction (FEC) mechanism based on Hamming code. We performed several test to determine the effectiveness of the proposed solution. The outcome show that our WUR system can be employed in environment where the Bit Error Rate (BER) induced by noise is up to 10^2, vice versa, when the BER induced by noise is in the order of 10 ́3 or below, it is not worth to use any Forward Error Correction (FEC) mechanism since it does not introduce any advantages compared to uncoded data.
In the context of energy-aware solutions, we present two protocols: REACTIVE and ALBA-WUR. REACTIVE is a low-power over-the-air programming (OAP) protocol we implemented to improve the energy efficiency and lower the image dissemination time of Deluge T2, a well-known OAP protocol implemented in TinyOS. To prove the effectiveness of REACTIVE we compared it to Deluge exploiting a testbed made of MagoNode motes. Results of our experiments show that the image dissemination time is 7 times smaller than Deluge, while the energy consumption drops 2.6 times. ALBA-WUR redesigns ALBA-R protocol, extending it to exploit advantages of WUR technology. We compared ALBA-R and ALBA-WUR in terms of current consumption and latency via simulations. Results show that ALBA-WUR
estimated network lifetime is decades longer than that achievable by ALBA-R. Furthermore, end-to-end packet latency features by ALBA-WUR is comparable to that of ALBA-R.
While the main goal of energy optimization approaches is motes lifetime maximization, in recent years a new research branch in WSN emerged: Energy Neutrality. In contrast to lifetime maximization approach, energy neutrality foresees the perennial operation of the network. This can be achieve only making motes use the harvested energy at an appropriate rate that guarantees an everlasting lifetime. In this thesis we stress that maximizing energy efficiency of a hardware platform dedicated to WSNs is the key to reach energy neutral operation (ENO), still providing reasonable data rates and delays. To support this conjecture, we designed a new hardware platform equipped with our wake-up radio (WUR) system able to support ENO, the MagoNode++. The MagoNode++ features a energy harvester to gather energy from solar and thermoelectric sources, a ultra low power battery and power management module and our WUR system to improve the energy efficiency of wireless communications. To prove the goodness in terms of current consumption of the MagoNode++ we ran a series of experiments aimed to assess its performance. Results show that the MagoNode++ consumes only 2.8 μA in Low Power Mode with its WRx module in listening mode.
While carrying on our research work on solutions trying to mitigate the energy problem, we also faced a challenging application context where the employment of WSNs is considered efficient and effective: structural health monitoring (SHM). SHM deals with the early detection of damages to civil and industrial structures and is emerging as a fundamental tool to improve the safety of these critical infrastructures. In this thesis we present two real world WSNs deployment dedicated to SHM. The first concerned the monitoring of the Rome B1 Underground construction site. The goal was to monitor the structural health of a tunnel connecting two stops. The second deployment concerned the monitoring of the structural health of buildings in earthquake-stricken areas. From the experience gained during these real world deployments, we designed the Modular Monitoring System (MMS). The MMS is a new low-power platform dedicated to SHM based on the MagoNode. We validated the effectiveness of the MMS low-power design performing energy measurements during data acquisition from actual transducers
Intergenerational conflict at US airlines:an unresolved Oedipal Complex?
Full text linkPurpose – The purpose of this study is to investigate how, if at all, organizational dynamics changed at US airlines after an industry wide modification to mandatory retirement age regulations in 2007. Findings challenge assumptions that society, organizations, and employees will all unequivocally benefit from abolishing mandatory retirement by investigating the impact of age related policy changes on US airline pilots.Design/methodology/approach: Forty-three semi-structured interviews were conducted with captains and copilots from US airlines between September 2010 and July 2011. From this data set, two informant subgroups emerged: 1) senior captains averaging 59 years of age; and 2) junior pilots averaging 43.5 years of age. Findings: Findings revealed that both senior and junior pilots reported retirement age policy changes created an antagonistic environment, pitting employees against each other in competition over scarce resources.Implications: Considerable research has been conducted identifying the policy and practice changes that employers need to adopt to retain older workers. However, few studies consider the psychological impact of these age-related workplace changes on employees or the organizational psychodynamics they might trigger. Originality/value: This article makes two main contributions. First, through use of the psychoanalytic construct of the Oedipus complex, the paper sheds light on some of the psychodynamic consequences of age related policy changes. Second, it challenges assumptions about workforce aging and the underlying causes of intergenerational conflict, highlighting ways that policy changes intended to eradicate discrimination against older workers can result in age discrimination against younger employees.Limitations: Article findings are based on empirical materials collected during an eleven month snapshot-in-time between September 2010 and July 2011 and interview data is based on a small subgroup of US airline pilots who self-selected to participate in the study. Therefore, findings are not unbiased and may not be generalizable across all airlines’ pilot workgroups.<br/
Self and stuff: accumulation in francophone literature and art
Full text linkNatalie Edwards, Amy L. Hubbel
Mr. William B. Fyfe: Master Architect of Calvin College and Seminary
No full textAn interview with Mr. William B. Fyfe, master architect of Calvin College and Seminary campuses, filmed April 1, 1991. Produced and directed by Amy L. Huizinga
Summary of Companion Guidelines on Replication and Reproducibility in Education Research
No full textRiegelman, Amy L.. (2019). Summary of Companion Guidelines on Replication and Reproducibility in Education Research. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/202954
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