22,515 research outputs found
Transparency effect in the emergence of monopolies in social networks
Power law degree distribution was shown in many complex networks. However, in
most real systems, deviation from power-law behavior is observed in social and
economical networks and emergence of giant hubs is obvious in real network
structures far from the tail of power law. We propose a model based on the
information transparency (transparency means how much the information is
obvious to others). This model can explain power structure in societies with
non-transparency in information delivery. The emergence of ultra powerful nodes
is explained as a direct result of censorship. Based on these assumptions, we
define four distinct transparency regions: perfect non-transparent, low
transparent, perfect transparent and exaggerated regions. We observe the
emergence of some ultra powerful (very high degree) nodes in low transparent
networks, in accordance with the economical and social systems. We show that
the low transparent networks are more vulnerable to attacks and the
controllability of low transparent networks is harder than the others. Also,
the ultra powerful nodes in the low transparent networks have a smaller mean
length and higher clustering coefficients than the other regions.Comment: 14 Pages, 3 figure
A 5D Building Information Model (BIM) for Potential Cost-Benefit Housing: A Case of Kingdom of Saudi Arabia (KSA)
The Saudi construction industry is going through a process of acclimatizing to a shifting fiscal environment. Due to recent fluctuations in oil prices, the Saudi construction sector decided to adjust to current trade-market demands and rigorous constitutional regulations because of competitive pressures. This quantitative study assesses and compares existing flat design vs. mid-terrace housing through cost estimation and design criteria that takes family privacy into consideration and meets the needs of Saudi Arabian families (on average consisting of seven members). Five pilot surveys were undertaken to evaluate the property preference type of Saudi families. However, Existing models did not satisfy the medium range family needs and accordingly a 5D (3D + Time + Cost) Building Information Modelling (BIM) is proposed for cost benefiting houses. Research results revealed that mid-terrace housing was the best option, as it reduced land usage and construction costs. While, 5D BIM led to estimate accurate Bill of Quantities (BOQ) and the appraisal of construction cost
Millimetre Wave Power Measurement
There is currently no traceable power sensor for millimetre wave frequencies above 110 GHz. This thesis investigates a novel approach to remove this limitation by combining the placement of a uniquely designed microchip directly in waveguide. The design of the chip is novel in that it does not rely on a supporting structure or an external antenna when placed in the waveguide.
The performance of the design was primarily analysed by computer simulation and verified with the measurement of a scale model. The results show
that it is feasible to measure high frequency power by placing a chip directly in waveguide. It is predicted that the chip is able to absorb approximately 60% of incident power. Any further efficiency would require modification of the chip substrate. However, this proposed design should allow the standards institutes a reference that will enable the calibration of equipment to beyond
110 GHz
ISS Space Plasma Laboratory: An ISS instrument package for investigating the opening/closing of solar and heliospheric magnetic fields
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140428/1/6.2014-1422.pd
A review of advances in pixel detectors for experiments with high rate and radiation
The Large Hadron Collider (LHC) experiments ATLAS and CMS have established
hybrid pixel detectors as the instrument of choice for particle tracking and
vertexing in high rate and radiation environments, as they operate close to the
LHC interaction points. With the High Luminosity-LHC upgrade now in sight, for
which the tracking detectors will be completely replaced, new generations of
pixel detectors are being devised. They have to address enormous challenges in
terms of data throughput and radiation levels, ionizing and non-ionizing, that
harm the sensing and readout parts of pixel detectors alike. Advances in
microelectronics and microprocessing technologies now enable large scale
detector designs with unprecedented performance in measurement precision (space
and time), radiation hard sensors and readout chips, hybridization techniques,
lightweight supports, and fully monolithic approaches to meet these challenges.
This paper reviews the world-wide effort on these developments.Comment: 84 pages with 46 figures. Review article.For submission to Rep. Prog.
Phy
Integrating Atomic Layer Deposition and Ultra-High Vacuum Physical Vapor Deposition for In Situ Fabrication of Tunnel Junctions
Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin,
pristine dielectrics on metal substrates, which is essential to many electronic
devices. Tunnel junctions are an excellent example which require a leak-free,
ultrathin dielectric tunnel barrier of typical thickness around 1 nm between
two metal electrodes. A challenge in the development of ultrathin dielectric
tunnel barrier using ALD is controlling the nucleation of dielectrics on metals
with minimal formation of native oxides at the metal surface for high-quality
interfaces between the tunnel barrier and metal electrodes. This poses a
critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor
deposition. In order to address these challenges, a viscous-flow ALD chamber
was designed and interfaced to an UHV magnetron sputtering chamber via a load
lock. A sample transportation system was implemented for in situ sample
transfer between the ALD, load lock, and sputtering chambers. Using this
integrated ALD-UHV sputtering system, superconductor-insulator-superconductor
(SIS) Nb/Al/Al2O3/Nb Josephson tunnel junctions were fabricated with tunnel
barriers of thickness varied from sub-nm to ~ 1 nm. The suitability of using an
Al wetting layer for initiation of the ALD Al2O3 tunnel barrier was
investigated with ellipsometry, atomic force microscopy, and electrical
transport measurements. With optimized processing conditions, leak-free SIS
tunnel junctions were obtained, demonstrating the viability of this integrated
ALD-UHV sputtering system for the fabrication of tunnel junctions and devices
comprised of metal-dielectric-metal multilayers.Comment: 25 pages, 13 figures, 1 tabl
Bioinspired reorientation strategies for application in micro/nanorobotic control
Engineers have recently been inspired by swimming methodologies of microorganisms in creating micro-/nanorobots for biomedical applications. Future medicine may be revolutionized by the application of these small machines in diagnosing, monitoring, and treating diseases. Studies over the past decade have often concentrated on propulsion generation. However, there are many other challenges to address before the practical use of robots at the micro-/nanoscale. The control and reorientation ability of such robots remain as some of these challenges. This paper reviews the strategies of swimming microorganisms for reorientation, including tumbling, reverse and flick, direction control of helical-path swimmers, by speed modulation, using complex flagella, and the help ofmastigonemes. Then, inspired by direction change in microorganisms,methods for orientation control for microrobots and possible directions for future studies are discussed. Further, the effects of solid boundaries on the swimming trajectories of microorganisms and microrobots are examined. In addition to propulsion systems for artificial microswimmers, swimming microorganisms are promising sources of control methodologies at the micro-/nanoscale
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