5,957 research outputs found
Techno-economic evaluation of reducing shielding gas consumption in GMAW whilst maintaining weld quality
A new method of supplying shielding gases in an alternating manner has been developed to enhance the efficiency of conventional gas metal arc welding (GMAW). However, the available literature on this advanced joining process is very sparse and no cost evaluation has been reported to date. In simple terms, the new method involves discretely supplying two different shielding gases to the weld pool at predetermined frequencies which creates a dynamic action within the liquid pool. In order to assess the potential benefits of this new method from a technical and cost perspective, a comparison has been drawn between the standard shielding gas composition of Ar/20%CO2, which is commonly used in UK and European shipbuilding industries for carbon steels, and a range of four different frequencies alternating between Ar/20%CO2 and helium. The beneficial effects of supplying the weld shielding gases in an alternating manner were found to provide attractive benefits for the manufacturing community. For example, the present study showed that compared with conventional GMAW, a 17 per cent reduction in total welding cost was achieved in the case of the alternating gas method and savings associated with a reduction in the extent of post-weld straightening following plate distortion were also identified. Also, the mechanical properties of the alternating case highlighted some marginal improvements in strength and Charpy impact toughness which were attributed to a more refined weld microstructure
Constraints on Beta Functions from Duality
We analyze the way in which duality constrains the exact beta function and
correlation length in single-coupling spin systems. A consistency condition we
propose shows very concisely the relation between self-dual points and phase
transitions, and implies that the correlation length must be duality invariant.
These ideas are then tested on the 2-d Ising model, and used towards finding
the exact beta function of the -state Potts model. Finally, a generic
procedure is given for identifying a duality symmetry in other single-coupling
models with a continuous phase transition.Comment: LaTeX, 6 page
Origine de la minĂ©ralisation des eaux des aquifĂšres discontinus sous couvert forestier de la zone Sud de la CĂŽte dâIvoire : cas de la rĂ©gion dâAbidjan-Agboville
Les eaux souterraines constituent lâune des principales sources dâapprovisionnement en eau potable de la population de la rĂ©gion dâAgboville-Abidjan. Cette Ă©tude se propose dâamĂ©liorer les connaissances sur les nappes souterraines et de dĂ©terminer lâorigine de la minĂ©ralisation des eaux souterraines de la rĂ©gion Ă partir dâune combinaison des mĂ©thodes hydrochimiques et de lâanalyse statistique multivariĂ©e. LâĂ©tude hydrochimique montre que les eaux de la rĂ©gion ont une tempĂ©rature moyenne de 27,7 ± 0,1 °C. Elles sont acides, avec un pH qui varie entre 3,8 et 6,9. Ces eaux sont faiblement minĂ©ralisĂ©es, ce qui confirme un trait chimique bien connu dans le pays et une diversitĂ© de faciĂšs chimiques en rapport avec la nature lithologique des terrains. Cependant, dâimportantes valeurs de la conductivitĂ© ont Ă©tĂ© rĂ©vĂ©lĂ©es dans les eaux de certaines localitĂ©s telles que Gori MâPo (819 ÎŒS.cm-1) et Lobo Akoudzin (503 ÎŒS.cm-1). Dans la rĂ©gion, les eaux souterraines se regroupent en quatre hydrofaciĂšs qui sont dominĂ©s par les eaux bicarbonatĂ©es calciques (61%) et les eaux chlorurĂ©es sodi-potassiques (22%). Les faciĂšs bicarbonatĂ©s sodi-potassiques (10%), et chlorurĂ©s calciques (7%) sont peu reprĂ©sentĂ©s dans ces eaux. Les principaux ions Ă lâorigine de la minĂ©ralisation des eaux sont issus de lâaltĂ©ration des roches, de lâhydrolyse des minĂ©raux silicatĂ©s tels que lâanorthite dans les plagioclases et de la dĂ©composition des minĂ©raux ferro-magnĂ©siens comme la biotite et lâamphibole prĂ©sentes dans les roches. A cela sâajoute le pluviolessivage des sols et une pollution dâorigine humaine liĂ©e aux activitĂ©s anthropiques.Mots clĂ©s. Abidjan-Agboville, analyse multivariĂ©e, eaux souterraines et hydrochimie
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Zenoâs paradox in decision making
Classical probability theory has been influential in modeling decision processes, despite empirical findings that have been persistently paradoxical from classical perspectives. For such findings, some researchers have been successfully pursuing decision models based on quantum theory. One unique feature of quantum theory is the collapse postulate, which entails that measurements (or in decision making, judgments) reset the state to be consistent with the measured outcome. If there is quantum structure in cognition, then there has to be evidence for the collapse postulate. A striking, a priori prediction, is that opinion change will be slowed down (under idealized conditions frozen) by continuous judgments. In physics, this is the quantum Zeno effect. We demonstrate a quantum Zeno effect in decision making in humans and so provide evidence that advocates the use of quantum principles in decision theory, at least in some cases
Evidence Base of Clinical Studies on Qi Gong: A Bibliometric Analysis
© 2020 The Authors Objective: This bibliometric study aimed to systematically and comprehensively summarize the volume, breadth and evidence for clinical research on Qigong. And this bibliometric analysis also can provide the evidence of this field. Design: Bibliometric analysis. Methods: All types of primary and secondary studies on humans were included: systematic reviews, randomized clinical trials, non-randomized controlled clinical studies, case series and case reports. Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Chinese Scientific Journal Database, Chinese Academic Conference Papers Database and Chinese Dissertation Database, PubMed and the Cochrane Library were searched from the date of inception to December 10, 2018. Bibliometric information, such as publication information, disease/condition, Qigong intervention and research results were extracted and analyzed. Results: A total of 886 clinical studies were identified: including 47 systematic reviews, 705 randomized clinical trials, 116 non-randomized controlled clinical studies, 12 case series and 6 case reports. The studies were conducted in 14 countries. The top 15 diseases/conditions studied were: diabetes, chronic obstructive pulmonary disease, hypertension, stroke, cervical spondylosis, lumbar disc herniation, insomnia, knee osteoarthritis, low back pain, and osteoporosis, Coronary heart disease, breast cancer, periarthritis of shoulder, depression, metabolic syndrome. Of the various Qigong exercises reported in these 886 clinical studies, Ba Duan Jin was the most frequently researched in 492 (55.5%) studies, followed by Health Qigong 107 (12.1%), Dao Yin Shu 85 (9.6%), Wu Qin Xi 67 (7.6%) and Yi Jin Jing 66 (7.4%). The most frequently used comparisons in randomized trials were maintaining normal way of life unchanged 149 (18.1%), the remaining controls included conventional treatment, mainly western medicine, Chinese herbal medicine, acupuncture, health education, psychological therapy, Yoga, Tai Chi and other non-drug therapy. The most frequently reported outcomes were physical function, quality of life, symptoms, pain and mental health indicators. Beneficial results from practicing Qigong were reported in 97% of studies. Conclusions: Qigong research publications have been increasing gradually. Reports on study types, participants, Qigong Intervention, and outcomes are diverse and inconsistent. There is an urgent need to develop a set of reporting standards for various interventions of Qigong. Further trials of high methodological quality with sufficient sample size and real world studies are needed to verify the effects of Qigong in health and disease management
Interpretations of suppression
We review the two main interpretations of suppression proposed in
the literature. The phase transition (or deconfining) scenario assumes that
below some critical value of the local energy density (or of some other
geometrical quantity which depends both on the colliding systems and on the
centrality of the collision), there is only nuclear absorption. Above this
critical value the absorptive cross-section is taken to be infinite, i.e. no
can survive in this hot region. In the hadronic scenario the
dissociates due both to nuclear absorption and to its interactions with
co-moving hadrons produced in the collision. No discontinuity exists in
physical observables. We show that an equally good description of the present
data is possible in either scenario.Comment: 12 pages, LaTeX, uses epsfig and ioplppt; review talk given by A.
Capella at the International Symposium on Strangness in Quark Matter,
Santorini (Greece), April 1997; Figs. 1 and 2 not available but can be found
in Refs. 13 and 6 respectivel
Central exclusive production of longlived gluinos at the LHC
We examine the possibility of producing gluino pairs at the LHC via the
exclusive reaction pp -> p+gluino+gluino+p in the case where the gluinos are
long lived. Such long lived gluinos are possible if the scalar super-partners
have large enough masses. We show that it may be possible to observe the
gluinos via their conversion to R-hadron jets and measure their mass to better
than 1% accuracy for masses below 350 GeV with 300/fb of data.Comment: 13 pages, 9 figures. Minor corrections to version
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