1,180 research outputs found

    High-resolution numerical approximation of traffic flow problems with variable lanes and free-flow velocities

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    This paper develops macroscopic traffic flow models for a highway section with variable lanes and free-flow velocities, that involve spatially varying flux functions. To address this complex physical property, we develop a Riemann solver that derives the exact flux values at the interface of the Riemann problem. Based on this solver, we formulate Godunov-type numerical schemes to solve the traffic flow models. Numerical examples that simulate the traffic flow around a bottleneck that arises from a drop in traffic capacity on the highway section are given to illustrate the efficiency of these schemes. Ā© 2005 The American Physical Society.published_or_final_versio

    Mechanical properties of composites filled with SMA particles and short fibers

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    ArticleCOMPOSITE STRUCTURES. 79(1): 90-96 (2007)journal articl

    Experimental investigation of a solar collector integrated with a pulsating heat pipe and a compound parabolic concentrator

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    The paper reports an experimental investigation of a newly proposed solar collector that integrates a closed-end pulsating heat pipe (PHP) and a compound parabolic concentrator (CPC). The PHP is used as an absorber due to its simple structure and high heat transfer capacity. The CPC has a concentration ratio of 3.4 and can be readily manufactured by three-dimensional printing. The CPC can significantly increase the incident solar irradiation intensity to the PHP absorber and also reduce the heat loss due to the decrease in the area of the hot surface. A prototype of the solar collector has been built, consisting of a PHP absorber bent by 4 mm diameter copper tube, CPC arrayed by 10 Ɨ 2 CPC units with the collection area of 300 Ɨ 427.6 mm2, a hot water tank and a glass cover. HFE7100 was utilized as the working fluid at a filling ratio of 40%. The operating characteristics and thermal efficiency of the solar collector were experimentally studied. The steady and periodic temperature fluctuations of the evaporation and condensation sections of the PHP absorber indicate that the absorber works well with a thermal resistance of about 0.26 Ā°C/W. It is also found that, as the main factor to the the thermal performance of the collector, thermal resistance of the PHP absorber decreases with increasing evaporation temperature. The collector apparently shows start-up, operational and shutdown stages at the starting and ending temperatures of 75 Ā°C. When the direct normal irradiance is 800 W/m2, the instantaneous thermal efficiency of the solar collector can reach up to 50%.The work was financially supported by the National Natural Science Foundation of China (51506004), Beijing Natural Science Foundation (3162009), Scientific Research Project of Beijing Educational Committee (KM201410016001) and Research Fund of Beijing University of Civil Engineering and Architecture

    Induction of resistance in cucumber against seedling damping-off by plant growth-promoting rhizobacteria (PGPR) Bacillus megaterium strain L8

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    Bacillus megaterium L8, a plant growth-promoting rhizobacterium (PGPR), was isolated and evaluated for its ability to induce resistance in cucumber against seedling damping-off caused by Pythium aphanidermatum. Root-splitting challenge experiments showed that L8 treatment of cucumber roots more effectively suppressed seedling damping-off than did the control as judged by seedling survival rate (83.45 versus 31.68% at 28 days), indicating that strain L8 is capable of inducing systemic disease resistance in cucumber. To explore the potential mechanism underlying the induced systemic resistance (ISR) mediated by L8, the expression profile of several plant defense-related enzymes: superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) were monitored in the roots treated with L8 or P. aphanidermatum and untreated leaves in a time course of 13 days. Levels of SOD, POD, CAT, PPO and PAL activities in the treated roots and untreated leaves of cucumber seedlings were all significantly higher as compared with the control and respectively peaked in the roots at 3, 3, 5, 5 and 5 days and correspondingly in the leaves at 5, 3, 5, 5 and 5 days post-inoculation. The enhanced expression patterns of the above enzymes following L8 or P. aphanidermatum treatment suggested that systemic induction of plant defense enzymes by L8 might account for its ability to provide effective protection for cucumber from seedling damping-off caused by the soil-borne fungal pathogen P. aphanidermatum.Key words: Plant growth-promoting rhizobacteria (PGPR), defense enzymes, damping-off of cucumber seedlings, induced resistance

    Corticosterone mediates electroacupuncture-produced anti-edema in a rat model of inflammation

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    <p>Abstract</p> <p>Background</p> <p>Electroacupuncture (EA) has been reported to produce anti-edema and anti-hyperalgesia effects on inflammatory disease. However, the mechanisms are not clear. The present study investigated the biochemical mechanisms of EA anti-inflammation in a rat model.</p> <p>Methods</p> <p>Three experiments were conducted on male Sprague-Dawley rats (n = 7ā€“8/per group). Inflammation was induced by injecting complete Freund's adjuvant (CFA) subcutaneously into the plantar surface of one hind paw. Experiment 1 measured plasma corticosterone (CORT) levels to see if EA regulates CORT secretion. Experiment 2 studied the effects of the adrenal gland on the therapeutic actions of EA using adrenalectomy (ADX) rats. Experiment 3 determined whether a prototypical glucocorticoid receptor antagonist, RU486, affects EA anti-edema. EA treatment, 10 Hz at 3 mA and 0.1 ms pulse width, was given twice, for 20 min each, once immediately after CFA administration and again 2 h post-CFA. Plasma CORT levels, paw thickness, indicative of the intensity of inflammation, and paw withdrawal latency (PWL) were measured 2 h and 5 h after the CFA injection.</p> <p>Results</p> <p>EA significantly increased plasma corticosterone levels 2 h (5 folds) and 5 h (10 folds) after CFA administration compared to sham EA control, but EA alone in naive rats and CFA alone did not induce significant increases in corticosterone. Adrenalectomy blocked EA-produced anti-edema, but not EA anti-hyperalgesia. RU486 (15 Ī¼l, 15 Ī¼g/Ī¼l), a prototypical glucocorticoid receptor antagonist, also prevented EA anti-edema.</p> <p>Conclusion</p> <p>The data demonstrate that EA activates the adrenals to increase plasma corticosterone levels and suppress edema and suggest that EA effects differ in healthy subjects and in those with pathologies.</p

    Ecological Supply Chain Based on By-Product Exchange

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    In this paper, the concept and primary design principles of ecological supply chain (ESC) are discussed. And the paper shows that companies can gain economical, social and environmental efficiencies simultaneously from implementing ecological supply chain management (ESCM). The cooperation processing based on by-product exchange in ESC is discussed with the decision-making criterion of eco-efficiency maximization. Accordingly, a pricing model is given. A case study of Guangxi Guitang Group is analyzed at last, which shows the multi-win brought by ESCM

    Evidence Base of Clinical Studies on Qi Gong: A Bibliometric Analysis

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    Ā© 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
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