46,606 research outputs found
Relay selection for wireless communications against eavesdropping: a security-reliability trade-off perspective
No full textThis article examines secrecy coding aided wireless communications from a source to a destination in the presence of an eavesdropper from an SRT perspective. Explicitly, security is quantified in terms of the intercept probability experienced at the eavesdropper, while the outage probability encountered at the destination is used to measure transmission reliability. We characterize the SRT of conventional direct transmission from the source to the destination and show that if the outage probability is increased, the intercept probability decreases, and vice versa. We first demonstrate that the employment of relay nodes for assisting source-destination transmission is capable of defending against eavesdropping, followed by quantifying the benefits of SRS as well as MRS schemes. More specifically, in the SRS scheme, only the single "best" relay is selected for forwarding the source signal to the destination, whereas the MRS scheme allows multiple relays to participate in this process. It is illustrated that both the SRS and MRS schemes achieve a better SRT than conventional direct transmission, especially upon increasing the number of relays. Numerical results also show that, as expected, MRS outperforms SRS in terms of its SRT. Additionally, we present some open challenges and future directions for wireless relay aided physical-layer security
Impact damage of composite laminates with high-speed waterjet
No full textRain erosion may cause substantial damage to aircrafts during supersonic flight. Such event is investigated here via high-speed waterjet impact on composite laminates. An experimental setup is developed to produce waterjets with the speed up to 700m/s and a finite element model of the waterjet-composite impact event is established. The consistency of experiment and simulation results validates the adopted numerical methods. The distribution of the water-hammer pressure is non-uniform and the maximum pressure occurs near the contact periphery when the water is about to eject laterally. After a high-speed (300∼560m/s) waterjet impacts a composite laminate, the impacted surface depression is observed, and the typical surface damage presents a central region with no visible surface damage surrounded by a faded “failure ring” with resin removal, matrix cracking and minor fiber fracture. Delamination occurs at the interfaces of adjacent layers with unequal dimensions and longitudinal matrix cracking appears on the back surface. Both the velocity and the diameter of waterjets are crucial factors on CFRP damage extents. Water-hammer pressure, the stagnation pressure and propagation of stress waves are failure mechanisms for most matrix damage in CFRP impacted by waterjets.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Structural Integrity & Composite
Effect of density value and gradient distribution on the deformation mechanism of foamed concrete
No full textFoamed concrete is an essential material in engineering that can be categorized into two types based on density distribution, namely uniform foamed concrete (UFC) and gradient foamed concrete (GFC). However, there exists a research gap concerning the mesoscopic deformation mechanism of UFC and GFC. The objective of this research is to bridge this gap by examining the quasi-static compression characteristics of UFCs with three distinct densities and GFCs with different density sequences. The results reveal that the strength of pore walls significantly influences the failure mechanism of UFCs with varying densities. Specifically, UFCs with low density exhibit weak pore-wall strength, leading to stress concentration at the pore-wall junction. During compression, these weak pore walls are widely dispersed within the specimen, resulting in a powdering failure mode. Conversely, UFCs with high density possess stronger pore walls, which prevent the powdering failure mode by maintaining adequate pore-wall strength. Nevertheless, the existence of a dominant crack within the specimen results in a splitting failure mode. In the context of GFCs, deformation occurs in a sequence from low to high density, with each layer exhibiting a failure mode corresponding to its density. Note that the last-deforming layer in this brittle gradient foam cannot attain the strength of the corresponding uniform foam. This is due to the failure of the second layer, which results in uneven contact surfaces and prompts the third layer to crack simultaneously. Finally, a statistical model is developed to forecast the compressive Stress–strain curve of foamed concrete, demonstrating remarkable agreement with experimental data
sj-docx-1-sci-10.1177_00368504221150060 - Supplemental material for Soil legacy effects on biomass allocation depend on native plant diversity in the invaded community
No full textSupplemental material, sj-docx-1-sci-10.1177_00368504221150060 for Soil legacy effects on biomass allocation depend on native plant diversity in the invaded community by Weitao Li, Xiaoting Bi and Yulong Zheng in Science Progress</p
Assessment of Self-Archiving in Institutional Repositories: Depositorship and Full-Text Availability
No full textThis research evaluates the success of open access self-archiving in several well-known institutional repositories. Two assessment factors have been applied to examine the current practice of self-archiving: depositorship and the availability of full text. This research discovers that the rate of author self-archiving is low and that the majority of documents have been deposited by a librarian or administrative staff. Similarly, the rate of full-text availability is relatively low, except for Australian repositories. By identifying different practices of self-archiving, repository managers can create new strategies for the operation of their repositories and the development of archiving policies
sj-xlsx-2-ade-10.1177_16878140211037767 – Supplemental material for Long-short term memory and gas path analysis based gas turbine fault diagnosis and prognosis
No full textSupplemental material, sj-xlsx-2-ade-10.1177_16878140211037767 for Long-short term memory and gas path analysis based gas turbine fault diagnosis and prognosis by Hongyu Zhou, Yulong Ying, Jingchao Li and Yaofei Jin in Advances in Mechanical Engineering</p
Load and environmental effects on the corrosion behavior of a Ti6Al4V alloy
No full textThis paper focuses on the static mechanical behavior of Ti-6Al-4V titanium alloy when exposed to several aggressive environments. Flat samples, with very light notches (i.e. Kt = 1.16), were tested under static loads, in inert environment and aggressive solutions: the samples gage sections were exposed to air and immerged in a NaCl solution (3.5%) and in a methanol solution (95%). The results of this experimental tests were analyzed and then compared with previous data coming from fatigue tests, carried out in paraffin oil, air, 3.5 wt.% NaCl, and in a methanol solution (95%), with the intent to decouple the effect of the alternating load and of the aggressive environment
sj-pdf-3-ade-10.1177_16878140211037767 – Supplemental material for Long-short term memory and gas path analysis based gas turbine fault diagnosis and prognosis
No full textSupplemental material, sj-pdf-3-ade-10.1177_16878140211037767 for Long-short term memory and gas path analysis based gas turbine fault diagnosis and prognosis by Hongyu Zhou, Yulong Ying, Jingchao Li and Yaofei Jin in Advances in Mechanical Engineering</p
sj-xlsx-1-ade-10.1177_16878140211037767 – Supplemental material for Long-short term memory and gas path analysis based gas turbine fault diagnosis and prognosis
No full textSupplemental material, sj-xlsx-1-ade-10.1177_16878140211037767 for Long-short term memory and gas path analysis based gas turbine fault diagnosis and prognosis by Hongyu Zhou, Yulong Ying, Jingchao Li and Yaofei Jin in Advances in Mechanical Engineering</p
Information Literacy and Librarian-Faculty Collaboration: A Model for Success:
No full textIn the age of information explosion and technological advancement, issues of information storage, organization, access, and evaluation have become necessarily important in our societies. Addressing issues of information literacy and designing how they can be best integrated in students' learning process are of critical importance. Library professionals in the United States, particularly in the academia, have realized the importance of information literacy and have attempted in various ways to address these issues. The ultimate goal is to make information literacy an integral part of the academic curriculum, thus helping students to succeed not only during their years in college but also for their lifelong career choices. This article will look at ways of how information literacy can best be incorporated into students' academic experience, and how this process can make students' learning meaningful and successful. Specifically, the author will examine the model of librarian-faculty collaboration in integrating information literacy into the curriculum, as demonstrated in the Ohio Five Colleges' Information Literacy Program.Publisher version of this article is available at: http://www.white-clouds.com/iclc/cliej/cl24.ht
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