733 research outputs found
Study effect of polyester fibres on engineering and durability properties of high volume fly ash concrete
Need and Growth of infrastructural facilities has been tremendously increased during last two decades across the world and hence the construction industry. In construction industry concrete of various kinds is the key material because of its potential benefits, low inherent energy and recycle values. On the earth concrete is the most consumed material after water; which needs to give due consideration towards the sustainability of concrete industries in particular.
The sustainability issue for concrete construction industry is not arrived due to one or more reasons related to the material or the technology itself. This includes it consumes large quantities of virgin materials; the principal binder in concrete is cement, a major contributor to greenhouse gas emissions that are implicated in global warming and climate change. Cement on other hand also utilizes natural resource in form of lime stone. Huge amount of energy is consumed in mining, blasting, crushing and transportation of these raw materials. Concrete structures suffer from durability issues which have an adverse effect on the resource productivity of the industry. Potential and optimize utilization of cementing material in concrete will definitely lead towards sustainable concrete construction. Use of industry waste and by products like fly ash, silica fume, grounded granular slag to partly replace cementing material to concrete system addresses all three sustainability issues, its adoption will enable the concrete construction industry to become more sustainable.
High Volume Fly Ash (HVFA) concrete is one of the solutions in this context of sustainable concrete construction. Though HVFA concrete technology has been developed way back and being proven technology for construction industries with potential benefits over regular concrete, it has been not become popular in developing countries due to one or other limitations like ductility, impact and abrasion resistance. Authors in this article will describe effect of polyester fibres on engineering properties Impact Strength and Abrasion Resistance of High Volume Fly Ash Concrete design mix M25, M30, M35 and M40. Test samples include replacement of cement by 50%, 55% and 60% class F fly ash. Paper contains test results of key material like fly ash, fibre, mix design for all grade, 60 min. slump comparison, comparative study of impact and abrasion resistance for plain and fibre reinforced HVFA at 28 and 56 days age. Comparative studies of economic gain with HVFA over conventional mix will also be presented to address sustainability issue
Identification of Patient Safety Improvement Targets in Successful Vascular and Endovascular Procedures: Analysis of 251Â hours of Complex Arterial Surgery
AbstractObjectivesTo investigate failures in patient safety for patients undergoing vascular and endovascular procedures to guide future quality and safety interventions.DesignSingle centre prospective observational study.Methods66 procedures (17 thoracoabdominal and 23 abdominal aortic aneurysms, 4 carotid and 22 limb procedures) were observed prospectively over a 9-month period (251 h operating time) by two trained observers. Event logs were recorded for each procedure. Two blinded experts identified and independently categorised failures into 22 types (using a validated category tool) and severity (5-point scale). Data are expressed as median (range). Statistical analysis was performed using Mann–Whitney U, Kruskal–Wallis and Spearman’s Rank tests.Results1145 failures were identified with good inter-assessor reliability (Cronbach’s alpha 0.844). The commonest failure types related to equipment (including unavailability, configuration and other failures) (269/1145 [23.5%]) and communication (240/1145 [21.0%]). A comparatively lower number of technical and psychomotor failures were identified (103 [9.0%]). The number of failures correlated with procedure duration (rho = 0.695, p < 0.001) but not anatomical site of the procedure or pathology of the disease process. Failure rate was higher in patients undergoing combined surgical/endovascular procedures compared to open surgery (median 5.7/h [IQR 4.2–8.1] vs 3.0/h [2.5–3.5]; p < 0.001). The severity of failures was similar (1.5/5 [1–2] vs 1/5 [1–2] respectively; p = 0.095). For combined procedures, failure rates were significantly higher during the endovascular phase (9.6/h [7.5–13.7]) compared to the non-endovascular phase (3.0/h [1.0–5.0]; p < 0.001).ConclusionsFailures in patient safety are common during complex arterial procedures. Few failures were severe, although minor failures during critical stages and accumulation of multiple minor failures may potentially be important. Failures occurred especially during the endovascular phase and were often related to equipment or communication aspects. Interventions to improve procedural safety and quality of care should primarily target these specific areas
A unified model for holistic power usage in cloud datacenter servers
Cloud datacenters are compute facilities formed by hundreds and thousands of heterogeneous servers requiring significant power requirements to operate effectively. Servers are composed by multiple interacting sub-systems including applications, microelectronic processors, and cooling which reflect their respective power profiles via different parameters. What is presently unknown is how to accurately model the holistic power usage of the entire server when including all these sub-systems together. This becomes increasingly challenging when considering diverse utilization patterns, server hardware characteristics, air and liquid cooling techniques, and importantly quantifying the non-electrical energy cost imposed by cooling operation. Such a challenge arises due to the need for multi-disciplinary expertise required to study server operation holistically. This work provides a unified model for capturing holistic power usage within Cloud datacenter servers. Constructed through controlled laboratory experiments, the model captures the relationship of server power usage between software, hardware, and cooling agnostic of architecture and cooling type (air and liquid). An exciting prospect is the ability to quantify the amount of non-electrical power consumed through cooling, allowing for more realistic and accurate server power profiles. This work represents the first empirically supported analysis and modeling of holistic power usage for Cloud datacenter servers, and bridges a significant gap between computer science and mechanical engineering research. Model validation through experiments demonstrates an average standard error of 3% for server power usage within both air and liquid cooled environments
Dynamic nuclear polarization and spin-diffusion in non-conducting solids
There has been much renewed interest in dynamic nuclear polarization (DNP),
particularly in the context of solid state biomolecular NMR and more recently
dissolution DNP techniques for liquids. This paper reviews the role of spin
diffusion in polarizing nuclear spins and discusses the role of the spin
diffusion barrier, before going on to discuss some recent results.Comment: submitted to Applied Magnetic Resonance. The article should appear in
a special issue that is being published in connection with the DNP Symposium
help in Nottingham in August 200
Production and Decay of D_1(2420)^0 and D_2^*(2460)^0
We have investigated and final states and
observed the two established charmed mesons, the with mass
MeV/c and width MeV/c and
the with mass MeV/c and width
MeV/c. Properties of these final states, including
their decay angular distributions and spin-parity assignments, have been
studied. We identify these two mesons as the doublet predicted
by HQET. We also obtain constraints on {\footnotesize } as a function of the cosine of the relative phase of the two
amplitudes in the decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by
sending mail to: [email protected]
Measurement of the branching fraction for
We have studied the leptonic decay of the resonance into tau
pairs using the CLEO II detector. A clean sample of tau pair events is
identified via events containing two charged particles where exactly one of the
particles is an identified electron. We find . The result is consistent with
expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS
94/1297, CLEO 94-20 (submitted to Physics Letters B
Study of the B^0 Semileptonic Decay Spectrum at the Upsilon(4S) Resonance
We have made a first measurement of the lepton momentum spectrum in a sample
of events enriched in neutral B's through a partial reconstruction of B0 -->
D*- l+ nu. This spectrum, measured with 2.38 fb**-1 of data collected at the
Upsilon(4S) resonance by the CLEO II detector, is compared directly to the
inclusive lepton spectrum from all Upsilon(4S) events in the same data set.
These two spectra are consistent with having the same shape above 1.5 GeV/c.
From the two spectra and two other CLEO measurements, we obtain the B0 and B+
semileptonic branching fractions, b0 and b+, their ratio, and the production
ratio f+-/f00 of B+ and B0 pairs at the Upsilon(4S). We report b+/b0=0.950
(+0.117-0.080) +- 0.091, b0 = (10.78 +- 0.60 +- 0.69)%, and b+ = (10.25 +- 0.57
+- 0.65)%. b+/b0 is equivalent to the ratio of charged to neutral B lifetimes,
tau+/tau0.Comment: 14 page, postscript file also available at
http://w4.lns.cornell.edu/public/CLN
Measurement of the Decay Asymmetry Parameters in and
We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\
decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for
the decay mode and \aLC = -0.45\pm 0.31 \pm
0.06 for the decay mode . By combining these
measurements with the previously measured decay rates, we have extracted the
parity-violating and parity-conserving amplitudes. These amplitudes are used to
test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures
as uuencoded postscript. Also available as
http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p
Observation of the Charmed Baryon Decays to , , and
We have observed two new decay modes of the charmed baryon into
and using data collected with the
CLEO II detector. We also present the first measurement of the branching
fraction for the previously observed decay mode . The branching fractions for these three modes relative to
are measured to be , , and , respectively.Comment: 12 page uuencoded postscript file, postscript file also available
through http://w4.lns.cornell.edu/public/CLN
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