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  • American Institute of Physics  (14,735)
  • MDPI Publishing  (10,327)
  • 2015-2019  (25,062)
  • 1980-1984
  • 2016  (25,062)
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  • 2015-2019  (25,062)
  • 1980-1984
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  • 1
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    American Institute of Physics
    In:  Journal of the Acoustical Society of America, 140 (4). pp. 2695-2702.
    Publication Date: 2020-07-16
    Description: The Green's function (GF) for the scalar wave equation is numerically constructed by an advanced geometric ray-tracing method based on the eikonal approximation related to the semiclassical propagator. The underlying theory is first briefly introduced, and then it is applied to acoustics and implemented in a ray-tracing-type numerical simulation. The so constructed numerical method is systematically used to calculate the sound field in a rectangular (cuboid) room, yielding also the acoustic modes of the room. The simulated GF is rigorously compared to its analytic approximation. Good agreement is found, which proves the devised numerical approach potentially useful also for low frequency acoustic modeling, which is in practice not covered by geometrical methods.
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2016-12-31
    Description: The issue of unitary evolution during creation and evaporation of a black hole remains controversial. We argue that some prominent cures are more troubling than the disease, demonstrate that their central element—forming of the event horizon before the evaporation begins—is not necessarily true, and describe a fully coupled matter-gravity system which is manifestly unitary.
    Electronic ISSN: 1099-4300
    Topics: Chemistry and Pharmacology , Physics
    Published by MDPI Publishing
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  • 3
    Publication Date: 2016-12-31
    Description: In this work, the one-parameter Fisher–Rényi measure of complexity for general d-dimensional probability distributions is introduced and its main analytic properties are discussed. Then, this quantity is determined for the hydrogenic systems in terms of the quantum numbers of the quantum states and the nuclear charge.
    Electronic ISSN: 1099-4300
    Topics: Chemistry and Pharmacology , Physics
    Published by MDPI Publishing
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  • 4
    Publication Date: 2016-12-31
    Description: We provide an upper bound for the amount of information a human translator adds to an original text, i.e., how many bits of information we need to store a translation, given the original. We do this by creating a Bilingual Shannon Game that elicits character guesses from human subjects, then developing models to estimate the entropy of those guess sequences.
    Electronic ISSN: 1099-4300
    Topics: Chemistry and Pharmacology , Physics
    Published by MDPI Publishing
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  • 5
    Publication Date: 2016-12-31
    Description: Since the weight of overburden is sustained by both the backfill body and the unmined solid coal in coal mining with compacted backfilling (CMCB) panels, the stress and deformation characteristics of the surrounding rocks in coal mining are radically changed. The overburden movement control mechanism by coordinating with backfill body and shield in CMCB was studied systematically in this paper. Based on the analysis of deformational and structural characteristics of surrounding rock in CMCB panels, the methods of theoretical analysis, numerical simulation and engineering test are employed. The results show that the fracture of the main roof is mainly controlled by the filling ratio φ and is non-correlated to the shield supporting pressure p. However, p has a significant control effect on the deflection of roof within the shield canopy length, and adversely affects the filling ratio. With the increase of the filling ratio of the gob, the maximum sagging of the immediate and the main roofs, the peak front and the influence range of the abutment pressures are gradually reduced. Correspondingly, the stable period of internal pressure of backfill body in the gob is shortened. Engineering practice shows that the sagging of the gob roof, the distribution of the abutment pressure, the distribution of the internal pressure in the backfill body, and the ground surface sagging results obtained by the in-situ measurement are approximately corresponding to the theoretical analysis and numerical simulation results.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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  • 6
    Publication Date: 2016-12-31
    Description: The transport of nutrients in forest soils predominantly occurs along preferential flow pathways (PFP). This study investigated the composition of phosphorus (P) forms in PFPs and soil matrix in several temperate beech forests with contrasting soil P contents in Germany. The PFPs were visualized using dye tracer experiments. Stained and unstained soil was sampled from three profile cuts per plot and analyzed for P fractions. The results show that labile P concentrations were highest in the O-layer and had the same range of values at all sites (240–320 mg·kg−1), although total P (TP) differed considerably (530–2330 mg·kg−1). The ratio of labile P to TP was significantly lower in the P-rich soil compared to the medium and P-poor soils. By contrast, the ratio of moderately labile P to TP was highest at the P-rich site. The shifts in P fractions with soil depth were generally gradual in the P-rich soil, but more abrupt at the others. The contents of labile and moderately labile P clearly differed in PFPs compared to soil matrix, but not statistically significant. The studied soils are characterized by high stone contents with low potential for P sorption. However, indications were found that labile organically bound P accumulates in PFPs such as biopores.
    Electronic ISSN: 1999-4907
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by MDPI Publishing
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  • 7
    Publication Date: 2016-12-31
    Description: To make driving assistance system more humanized, this study focused on the prediction and assistance of drivers’ perception-response time on mountain highway curves. Field tests were conducted to collect real-time driving data and driver vision information. A driver-vision lane model quantified curve elements in drivers’ vision. A multinomial log-linear model was established to predict perception-response time with traffic/road environment information, driver-vision lane model, and mechanical status (last second). A corresponding assistance model showed a positive impact on drivers’ perception-response times on mountain highway curves. Model results revealed that the driver-vision lane model and visual elements did have important influence on drivers’ perception-response time. Compared with roadside passive road safety infrastructure, proper visual geometry design, timely visual guidance, and visual information integrality of a curve are significant factors for drivers’ perception-response time.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI Publishing
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  • 8
    Publication Date: 2016-12-31
    Description: Parks have the potential to increase physical activity at the community level by providing opportunities to be active. In order to inform interventions to promote physical activity in parks, insight is needed concerning park user characteristics, the activity level of park users, the types of activities performed and associations between park areas and temporal variables with observed physical activity levels. Park user characteristics (sex, age, ethnicity and activity level) were recorded within pre-defined park areas in two parks in Ghent (Belgium) using the System for Observing Play and Recreation in Communities (SOPARC). Most park users were male, adult, and engaged in vigorous-intensity physical activity (48%). Most popular activities were biking (38%), sitting (23%) and walking (15%); accordingly, trails were used most and had the highest levels of physical activity compared to other park areas. Parks were used least frequently in the morning, during the weekend and by seniors. Therefore, active park use during morning periods, on weekend days and by seniors should be promoted and urban planners should consider that different park areas can possibly elicit varying activity levels among park users.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI Publishing
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  • 9
    Publication Date: 2016-12-31
    Description: Mercury is a toxic metal and is used in small scale gold mining. In Portovelo, Ecuador, mercury has been an environmental and health problem for decades. The target of this study was to assess the mercury concentration in the urine of miners from Portovelo/Zaruma to establish a prevalence of high values. Eight hundred and sixty-five (865) urine samples were collected and analysed for their mercury content, using cold vapor atom absorption spectroscopy. The prevalence of high mercury values (>25 μg/L) was estimated. Forty-four (44) miners with mercury levels >15 μg/L filled in a questionnaire for characteristics and possible confounders, and were examined for intoxication symptoms to establish the ten points medical score sum. The median urine value was 1.8 μg/L; 78.3% of miners were below 7 μg/L and were not at risk of an intoxication, whereas 5.9% of miners exceeded the limit of 25 μg/L and were probable to experience intoxication symptoms. The medical score sum had a range of 2 to 8 points with a median of 6. The low prevalence of high mercury concentrations shows that the politics and techniques to eliminate the use of mercury are being successfully implemented. Further studies are needed to identify factors enabling this process.
    Print ISSN: 1661-7827
    Electronic ISSN: 1660-4601
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by MDPI Publishing
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  • 10
    Publication Date: 2016-12-31
    Description: The near-repeat phenomenon refers to the increased risk of repeat victimization not only at the same location but at nearby locations up to a certain distance and for a certain time period. In recent research, near-repeat victimization has been repeatedly confirmed for different crime types such as burglaries or shootings. In this article the near-repeat phenomenon is analyzed for each day of the week separately. That is, the near-repeat pattern is evaluated for all consecutive Mondays, Tuesdays, Wednesdays, etc. included in the dataset. These consecutive weekdays represent the fictive set of consecutive dates to allow for spatial and temporal analysis of crime patterns. Using these principles, it is hypothesized that street robberies cluster in space and time and by the same day of the week. This research analyzes street robberies from 2009 to 2013 in Vienna, Austria. The overall research goal investigates whether near-repeat patterns of robberies exist by weekdays and in an additional step by time of day, and whether these near-repeat patterns differ from each other and from purely spatial patterns. The results of this research confirm the existence of near-repeat patterns by weekday and especially by time of day. Distinctive locations have been identified that differ greatly per weekday and time of day. Based on this information, law enforcement agencies in Austria can optimize strategic planning of police resources in combating robberies.
    Electronic ISSN: 2220-9964
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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