Cost Evaluation of Optical Packet Switches Using Both Limited-Range and Full-Range Converters for Contention Resolution

Author(s):  
V. Eramo ◽  
M. Listanti ◽  
A. Germoni
2018 ◽  
Vol 120 (5) ◽  
pp. 1-40
Author(s):  
Jack Schneider ◽  
Rebecca Jacobsen ◽  
Rachel S. White ◽  
Hunter Gehlbach

Purpose/Objective Under the reauthorized Every Student Succeeds Act (ESSA), states and districts retain greater discretion over the measures included in school quality report cards. Moreover, ESSA now requires states to expand their measurement efforts to address factors like school climate. This shift toward more comprehensive measures of school quality provides an opportunity for states and districts to think intentionally about a basic question: What specific information should schools collect and report to their communities? Setting This study took place in the community surrounding a small, highly diverse urban school district. Population/Participants Forty-five local residents representing a range of demographic backgrounds participated in a modified deliberative poll with an experimental treatment. Intervention/Program/Practice We randomly assigned participants into two conditions. In the first, participants accessed the state web portal, which houses all publicly available educational data about districts in the state. In the second condition, participants accessed a customized portal that contained a wider array of school performance information collected by the research team. Research Design This mixed-methods study used a modified deliberative polling format, in conjunction with a randomized controlled field trial. Data Collection and Analysis Participants in both conditions completed a battery of survey items that were analyzed through multiple regressions. Findings/Results When users of a more holistic and comprehensive data system evaluated unfamiliar schools, they not only valued the information more highly but also expressed more confidence in the quality of the schools. Conclusions/Recommendations We doubt that more comprehensive information will inevitably lead to higher ratings of school quality. However, it appears—both from prior research, from theory, and from this project—that deeper familiarity with a school often fosters more positive perceptions. This may be because those unfamiliar with particular schools rely on a limited range of data, which fail to adequately capture the full range of performance variables, particularly in the case of urban schools. We encourage future exploration of this topic, which may have implications for school choice, parental engagement, and accountability policy.


Author(s):  
Bettina Albers

The topic of the previous work of Albers and Wilmanski was the study of monochromatic surface waves at the boundary between a porous medium and a vacuum. This article is an extension of this research to the propagation of surface waves on the interface between a porous halfspace and a fluid halfspace. Results for phase and group velocities and attenuations are shown in dependence on both the frequency and the surface permeability. In contrast to classical papers on surface waves where only the limits of the frequency ω →0, ω →∞ and the limits of the surface permeability (fully sealed and fully open boundary) were studied, we investigate the problem in the full range of both parameters. For the analysis we use the ‘simple mixture model’ which is a simplification of the classical Biot model for poroelastic media. The construction of a solution is shown and the dispersion relation solved numerically. There exist three surface waves for this boundary: a leaky Rayleigh wave and both a true and a leaky Stoneley wave. The true Stoneley wave exists only in a limited range of the surface permeability.


The North American Arctic was one of the last regions on Earth to be settled by humans, due to its extreme climate, limited range of resources, and remoteness from populated areas. Despite these factors, it holds a rich and complex history relating to Inuit, Iñupiat, Inuvialuit, Yupik, and Aleut peoples and their ancestors. The artifacts, dwellings, and food remains of these ancient peoples are remarkably well preserved due to cold temperatures and permafrost, allowing archaeologists to reconstruct their lifeways with great accuracy. Furthermore, the combination of modern Elders’ traditional knowledge with the region’s high-resolution ethnographic record allows past peoples’ lives to be reconstructed to a level simply not possible elsewhere. Combined, these factors yield an archaeological record of global significance—the Arctic provides ideal case studies relating to issues as diverse as the impacts of climate change on human societies, the complex process of interaction between indigenous peoples and Europeans, and the dynamic relationships between environment, economy, social organization, and ideology in hunter-gatherer societies. In this book, each Arctic cultural tradition is described in detail, with up-to-date coverage of recent interpretations of all aspects of their lifeways. Additional chapters cover broad themes applicable to the full range of arctic cultures, such as trade, stone tool technology, ancient DNA research, and the relationship between archaeology and modern arctic communities. The resulting volume, written by the region’s leading researchers, is by far the most comprehensive coverage of North American arctic archaeology ever assembled.


2019 ◽  
Vol 67 (4) ◽  
pp. 329-338
Author(s):  
Zbyněk Zachoval ◽  
Jakub Major ◽  
Ladislav Roušar ◽  
Ján Rumann ◽  
Jan Šulc ◽  
...  

Abstract Full-width sharp-edged broad-crested rectangular weirs in the range 0.1 < h/L ≤ 0.3 situated in rectangular channels are frequently used in submerged flow conditions. To determine the discharge for the submerged flow, submergence coefficient and modular limit shall be known. This article deals with their determination upon a theoretic derivation and experimental research. The equation for modular limit has been determined from energy balance with simplifications. To validate it, extensive experimental research was carried out. However, the derived equation is too complicated for practical use which is why it was approximated by a simple equation applicable for the limited range. The equation for submergence coefficient was derived by modifying Villemonte’s application of the principle of superposition and its coefficients were determined using the data from experimental research of many authors. The new system of equations computes the discharge more accurately than other authors’ equations, with the error of approximately ±10% in full range of the measured data.


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