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Rapid Design and Manufacture of Ultralight Cellular Materials
This paper details the design, manufacture and testing of regular metallic lattice structures
with unit cell sizes in the range 0.8mm to 5mm and truss elements of 100-500 µm in diameter [1].
The structures were manufactured using Selective Laser Melting (SLM) technology from 316L
stainless steel. Compression tests have shown yield loadings of over 3.5kN despite being only
18mm by 18mm by 10mm in height, the results are favourably comparable to current
commercially available metallic foams. Software has been developed that creates slice files
without the use of CAD software or STL files and is capable of producing lattices within a
volume defined by a STL file.Mechanical Engineerin
High velocity impact resistance of fibre metal laminates
The high velocity impact resistance of fibre metal laminates (FMLs) based on combinations of three
different aluminium alloys (6161-O, 6061-T6, 7075-T6) and a glass fibre reinforced epoxy resin have
been investigated both experimentally and numerically. A series of perforation tests on multilayer
configurations, ranging from a simple 2/1 lay-up to a seven ply 4/3 laminate. High velocity impact was
conducted using a projectile gas-gun launcher, operating in the velocity range between 119 m/s and
252 m/s.[1] The impact response of fibre metal laminates samples was characterised by determining
the energy required to perforate the panels. A stereoscopic Digital Image Correlation (DIC) method
was adopted to measure full-field deformations and strain for FMLs which providing the full field
strain history and 3D measurements up to sample perforation. The perforation resistance of the panels
was predicted using the finite element analysis package Abaqus/Explicit. A vectorized user-defined
material subroutine (VUMAT) was employed to define Hashin’s 3D rate-dependant damage criteria
for the composite layers. The subroutine was implemented into the commercial finite element software
ABAQUS/Explicit to simulate the deformation and failure of FMLs. Agreement between the
predictions of the finite element models and the experimental data was good across the range of
configurations. Ballistic limit of those FMLs was obtained from both the experimental tests and
numerical approaches
Use of conventional optical fibers and fiber Bragg gratings for damage detection in advanced composite structures: A review
Structurally integrated sensors which are capable of continuous structural health monitoring represent an attractive option in view of their potential for providing real-time assessment/ warning of structural damage. In recent years, optical fiber systems have attracted a considerable amount of attention and have been shown to be a very attractive option for health monitoring in advanced composite materials. These sensors have either been embedded or surfacebonded to the host material thereby allowing continuous assessment of the health of the structure. Structural health assessment takes the form of damage detection and/or monitoring of specific health indicators. In the former approach, the optical fiber systems are generally optimized to increase their sensitivity to the presence of damage in the composite structure, while the latter approach relies on the examination of characteristic changes in the monitored parameter to infer a loss in structural integrity. To this end, many investigators have demonstrated the potential of optical fiber sensors, most particularly intensity-based optical fiber systems and fiber Bragg grating sensors for structural health monitoring of advanced composite materials. The initial part of this paper provides an up-to-date review of the applications of optical fiber sensors in composite materials, focussing particularly on the use of intensitybased optical fiber systems and fiber Bragg grating sensors for damage detection. These optical fiber systems have been shown to be capable of detecting impact damage, transverse cracking, and delamination, and have the ability to monitor strain in structures. The introduction of optical fiber sensors into a composite material can inadvertently produce a geometrical discontinuity in the vicinity of the sensor. Numerous experimental investigations have also been performed to assess the possible reduction in the properties of the host structure. A review of the findings of these investigations reported in the literature is also given. This review article cites 161 references
LR characterization of chirotopes of finite planar families of pairwise disjoint convex bodies
We extend the classical LR characterization of chirotopes of finite planar
families of points to chirotopes of finite planar families of pairwise disjoint
convex bodies: a map \c{hi} on the set of 3-subsets of a finite set I is a
chirotope of finite planar families of pairwise disjoint convex bodies if and
only if for every 3-, 4-, and 5-subset J of I the restriction of \c{hi} to the
set of 3-subsets of J is a chirotope of finite planar families of pairwise
disjoint convex bodies. Our main tool is the polarity map, i.e., the map that
assigns to a convex body the set of lines missing its interior, from which we
derive the key notion of arrangements of double pseudolines, introduced for the
first time in this paper.Comment: 100 pages, 73 figures; accepted manuscript versio
Scaling the Non-linear Impact Response of Flat and Curved Composite Panels
The application of scaling laws to thin flat and curved composite panels exhibiting nonlinear response when subjected to low-velocity transverse impact is investigated. Previous research has shown that the elastic impact response of structural configurations exhibiting geometrically linear response can be effectively scaled. In the present paper, a preliminary experimental study is presented to assess the applicability of the scaling laws to structural configurations exhibiting geometrically nonlinear deformations. The effect of damage on the scalability of the structural response characteristics, and the effect of scale on damage development are also investigated. Damage is evaluated using conventional methods including C-scan, specimen de-plying and visual inspection of the impacted panels. Coefficient of restitution and normalized contact duration are also used to assess the extent of damage. The results confirm the validity of the scaling parameters for elastic impacts. However, for the panels considered in the study, the extent and manifestation of damage do not scale according to the scaling laws. Furthermore, the results indicate that even though the damage does not scale, the overall panel response characteristics, as indicated by contact force profiles, do scale for some levels of damage
From Acting What’s next to Speeding Trap: Co-Evolutionary Dynamics of an Emerging Technology-Leader
JEL Classifications: O33, O53, L63[[abstract]]How does technological innovation emerge and evolve? We approach such an inquiry by synthesizing the perspectives of dynamic capabilities and co-evolutionary dynamics to portray organizational routines and multi-phase strategic renewals of an emerging technology-leader. To untangle the emergence of technological innovation, we conducted a longitudinal case study on the first and the largest dedicated semiconductor foundry, TSMC, located in the emerging economy of Taiwan. The firm-case of TSMC illustrates two unique co-evolutionary paths, that is, transforming from industry-latecomer to technology-leader and from process innovation to product innovation. We found multi-motor co-evolutionary dynamics between TSMC and the semiconductor industry, where its co-evolutionary mechanism of managed selection in its creating phase of mature process-innovation (1987-1998) has migrated to hierarchical renewal in its extending phase of advanced process-innovation (1999-2001), and then to holistic renewal in its modifying phase of product-innovation (2002-2007). During such paths, our research discovered a unique type of organizational routines, acting what’s next because TSMC has proactively searched for potential problems sooner than its competitors. However, such routines, although driving technological innovation, also lead to a unique type of success-trap, that is, speeding trap. When an emerging technology-leader fundamentally changes the industrial structures to over-specs, the growth driven by technology speeding may trap such a leader in a loop of over-exploration.[[sponsorship]]The authors are grateful to the research grant from the National Science Council (NSC) in Taiwan. The earlier manuscript of this paper was presented at the 2009 Annual Meeting of Academy of International Business (AIB) in San Diego, USA.[[notice]]補正完畢[[journaltype]]國外[[ispeerreviewed]]Y[[booktype]]紙本[[booktype]]電子版[[countrycodes]]CA
Measuring attitude towards Buddhism and Sikhism : internal consistency reliability for two new instruments
This paper describes and discusses the development and empirical properties of two new
24-item scales – one measuring attitude toward Buddhism and the other measuring attitude
toward Sikhism. The scale is designed to facilitate inter-faith comparisons within the
psychology of religion alongside the well-established Francis Scale of Attitude toward
Christianity. Data were obtained from a multi-religious sample of 369 school pupils aged
between 13 and 15 in London. Application of the two scales demonstrated that adolescents
had a more positive attitude to Buddhism than Sikhism. The findings confirm the reliability
of the scales and commend them for further use
A Multi-telescope Campaign on FRB 121102: Implications for the FRB Population
We present results of the coordinated observing campaign that made the first
subarcsecond localization of a Fast Radio Burst, FRB 121102. During this
campaign, we made the first simultaneous detection of an FRB burst by multiple
telescopes: the VLA at 3 GHz and the Arecibo Observatory at 1.4 GHz. Of the
nine bursts detected by the Very Large Array at 3 GHz, four had simultaneous
observing coverage at other observatories. We use multi-observatory constraints
and modeling of bursts seen only at 3 GHz to confirm earlier results showing
that burst spectra are not well modeled by a power law. We find that burst
spectra are characterized by a ~500 MHz envelope and apparent radio energy as
high as erg. We measure significant changes in the apparent
dispersion between bursts that can be attributed to frequency-dependent
profiles or some other intrinsic burst structure that adds a systematic error
to the estimate of DM by up to 1%. We use FRB 121102 as a prototype of the FRB
class to estimate a volumetric birth rate of FRB sources Mpc yr, where is the number of bursts per
source over its lifetime. This rate is broadly consistent with models of FRBs
from young pulsars or magnetars born in superluminous supernovae or long
gamma-ray bursts, if the typical FRB repeats on the order of thousands of times
during its lifetime.Comment: 17 pages, 7 figures. Submitted to AAS Journal
Self-similarity and Reynolds number invariance in Froude modelling
This review aims to improve the reliability of Froude modelling in fluid flows where both the Froude number and Reynolds number are a priori relevant. Two concepts may help to exclude significant Reynolds number scale effects under these conditions: (i) self-similarity and (ii) Reynolds number invariance. Both concepts relate herein to turbulent flows, thereby excluding self-similarity observed in laminar flows and in non-fluid phenomena. These two concepts are illustrated with a wide range of examples: (i) irrotational vortices, wakes, jets and plumes, shear-driven entrainment, high-velocity open channel flows, sediment transport and homogeneous isotropic turbulence and (ii) tidal energy converters, complete mixing in contact tanks and gravity currents. The limitations of self-similarity and Reynolds number invariance are also highlighted. Many fluid phenomena with the limitations under which self-similarity and Reynolds number invariance are observed are summarised in tables, aimed at excluding significant Reynolds number scale effects in physical Froude-based models
Evaluating Tuberculosis Case Detection in Eritrea
We used results from a national tuberculosis prevalence survey in Eritrea to calculate case detection rate (CDR) and compared it with the published CDR. The CDR obtained from the survey was ≈40%, whereas the CDR published by the World Health Organization was 3× lower (14%)
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