Derive Mean Values Research Articles

On some discrete mean values of higher derivatives of Hardy’s Z-function

Yıldırım obtained an asymptotic formula of the discrete moment of [Formula: see text] over the zero of the higher derivatives of Hardy’s [Formula: see text]-function. We give a generalization of his result on Hardy’s [Formula: see text]-function.

Mean Values of Derivatives of $L$-functions for Cyclotomic Characters in Function Fields

We compute the mean value of derivatives of $L$-functions for cyclotomic characters in function fields. We also show the non-vanishing property of derivatives of $L$-functions for cyclotomic characters in function fields.

Minkowski-Fock states in accelerated frames

An explicit Wigner formulation of Minkowski particle states for noninertial observers is unknown. Here, we derive a general prescription to compute the characteristic function for Minkowski-Fock states in accelerated frames. For the special case of single-particle and two-particle states, this method enables one to derive mean values of particle numbers and correlation function in the momentum space, and the way they are affected by the acceleration of the observer. We show an indistinguishability between Minkowski single-particle and two-particle states in terms of Rindler particle distribution that can be regarded as a way for the observer to detect any acceleration of the frame. We find that for two-particle states the observer is also able to detect acceleration by measuring the correlation between Rindler particles with different momenta.

The decreasing of the influence of parasitic inductance of tested object on the accuracy of its electrical capacitance measurement

This paper gives a description of measurement technique which can be used in practice of carrying out estimation of electrical capacitance of tested object with substantial stray inductance. Electrical capacitance is determined as a ratio of mean value of discharge current to the mean value of time derivative, taken from voltage on unknown capacitance. The decreasing of deleterious impact of stray inductance on accuracy of measurements is achieved by proper selection of the duration of analyzed signals. In proposed technique the duration is limited by instants of time that correspond to the maximum value of discharge current and to the termination of transient. The accuracy of described method for electrical capacitance estimation is affected by noisy components of obtained oscillograms. This deleterious impact can be alleviated by smoothing of time dependence by applying of least square method. Another reason for lost of accuracy is associated with possible influence of skin-effect in conductive elements of discharge circuit, which can cause time dependence of resistance and inner inductance of conductive parts of tested object and discharge circuit. Described technique, however, is based on taking into consideration independent on time parameters of equivalent lamped discharge circuit. Nevertheless, the example of practical implementation has shown that described approach allows to partially mitigate the influence of stray inductance on carried out measurements of electrical capacitance, as the value of relative error turned out to be equal to 2.04%

IDENTIFICATION OF THE FIRST LEVEL MANAGERS’ RELEVANCE IN THE MANAGEMENT CHAIN: CASE STUDY OF WEST LITHUANIA COMPANIES

Assessment of the first level managers only in respect of their compliance with the requirements set for a particular job position isnot sufficient. A tool facilitating identification of the relevance of the first level managers in certain management chain is required asit would ensure effectiveness of their performance and harmony in the management chain. The present article aims at emphasisingthe feasibility of identification of the relevance of the first level managers in the management chain (MLM–FLM–SUB) throughpersonality traits. The research analysed the following members (links) of the management chain: first level managers (FLM), theirdirect supervisors – mid-level managers (MLM) and subordinates (SUB) – working in five furniture manufacturing companies ofthe West Lithuania Region. “The Big Five” method was applied as research instrument to assess personality traits of the first levelmanagers. Quantitative analysis enabled modelling of a graph, which represents a derived mean value of the assessment of thefirst level managers’ personality traits, designated to identify disharmonious chains in companies. When identifying the first levelmanagers’ relevance in the management chain, only individual evaluations performed by the members /links of the chains werereferred to and used as a basis for evaluation of personal traits of particular first level manager only. The obtained data supplementsdirect indicators of FLM performance assessment. KEYWORDS: first level managers, evaluation, personality traits, hierarchy, management chain, harmony, regional problems. DOI: http://dx.doi.org/ 10.15181/rfds.v11i3.610

Intercomparison of Thermal Conductivity Measurements on a Nanoporous Organic Aerogel

Due to their special combination of nanostructure and high porosity, aerogels are key materials for high performance thermal insulation. However, measuring reliable thermal conductivity values, which are essential for material’s optimization and as product parameter, is a challenging task in the case of aerogels. Experimentally derived thermal conductivity values for aerogels are so far more or less influenced by the experimental set-up and the experimental conditions and have to be carefully discussed. Here we present results of an intercomparison on thermal conductivity measurements performed for a polyurethane aerogel produced on a pilot scale as stiff panels by BASF. Prior to the intercomparison, the material was checked for reproducibility in production and homogeneity. The dependence of thermal conductivity on atmospheric pressure and temperature was also determined. We discuss the results submitted by 12 participants with respect to the different experimental techniques applied and identify experimental parameters with severe impact on the resulting thermal conductivities. The derived mean values for the thermal conductivity at 20 °C, 40 °C and 60 °C were related with relative uncertainties in the range from 0.6 % to 0.9 %. The dependence of the derived thermal conductivity values on the geographical location of the participating laboratory and the atmospheric weather conditions could be clearly observed and the precision of the results could be significantly improved by correcting for these effects. The values had to be partly corrected up to 2.5 %.

Observations of atmospheric 14CO2 at Anmyeondo GAW station, South Korea: implications for fossil fuel CO2 and emission ratios

Abstract. To understand the Korean Peninsula's carbon dioxide (CO2) emissions and sinks as well as those of the surrounding region, we used 70 flask-air samples collected during May 2014 to August 2016 at Anmyeondo (AMY; 36.53∘ N, 126.32∘ E; 46 m a.s.l.) World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) station, located on the west coast of South Korea, for analysis of observed 14C in atmospheric CO2 as a tracer of fossil fuel CO2 contribution (Cff). Observed 14C ∕ C ratios in CO2 (reported as Δ values) at AMY varied from −59.5 ‰ to 23.1 ‰, with a measurement uncertainty of ±1.8 ‰. The derived mean value Cff of (9.7±7.8) µmol mol−1 (1σ) is greater than that found in earlier observations from Tae-Ahn Peninsula (TAP; 36.73∘ N, 126.13∘ E; 20 m a.s.l., 28 km away from AMY) of (4.4±5.7) µmol mol−1 from 2004 to 2010. The enhancement above background mole fractions of sulfur hexafluoride (Δx(SF6)) and carbon monoxide (Δx(CO)) correlate strongly with Cff (r>0.7) and appear to be good proxies for fossil fuel CO2 at regional and continental scales. Samples originating from the Asian continent had greater Δx(CO) : Cff(RCO) values, (29±8) to (36±2) nmol µmol−1, than in Korean Peninsula local air ((8±2) nmol µmol−1). Air masses originating in China showed (1.6±0.4) to (2.0±0.1) times greater RCO than a bottom-up inventory, suggesting that China's CO emissions are underestimated in the inventory, while observed RSF6 values are 2–3 times greater than inventories for both China and South Korea. However, RCO values derived from both inventories and observations have decreased relative to previous studies, indicating that combustion efficiency is increasing in both China and South Korea.

Asymmetric dimethylarginine and L-homoarginine prospectively relate to carotid wall thickness in a South African cohort.

The L-arginine derivatives asymmetric (ADMA) and symmetric dimethylarginine (SDMA), as well as L-homoarginine may have opposing effects in the pathogenesis of atherosclerosis. We aimed to investigate (i) 5-year changes in arginine derivatives, and (ii) the association between baseline arginine derivatives and follow-up measures of carotid wall thickness in South Africans. This study included men (n = 187) and women (n = 396) who took part in the 2010 and 2015 data collections of the South African arm of the Prospective Urban and Rural Epidemiology (PURE) study. Arginine derivatives were determined in plasma with liquid chromatography-tandem mass spectrometry. Carotid intima-media thickness (cIMT) and cross-sectional wall area (CSWA) were determined with B-mode ultrasonography. Mean values of arginine derivatives did not change over time. In the study group, follow-up cIMT (β = -0.10 p = 0.018) and CSWA (β = -0.12; p = 0.004) inversely associated with baseline L-homoarginine, and cIMT inversely associated with ADMA (β = -0.09; p = 0.033). In women, CSWA inversely associated with both ADMA (β = -0.11; p = 0.034) and L-homoarginine (β = -0.11; p = 0.024). No such associations were found in men. These results suggest that higher levels of L-homoarginine may play a protective role against vascular injury and delay progression of carotid wall thickening in this cohort. The role of ADMA in atherosclerosis deserves further investigation in this population.

Predicting onset conditions of a free piston Stirling engine

This research predicts the onset conditions of the free piston Stirling engines using analytical solution of the governing equations and averaging-based Lyapunov technique. In this regard, firstly, the linear dynamic equations of the free piston Stirling engines are extracted. Then, the analytical solutions of the motion equations of the displacer and the power pistons are obtained. Afterwards, these analytical solutions are put into the mean value of the time derivative of Lyapunov function to obtain a convenient relation which provides meaningful information regarding the onset condition of free piston Stirling engines. The mentioned procedure has been verified by the results of multiple numerical simulations and the experimental data (B10-B and SUTech-SR-1). In addition, the results of this method have been validated by the outcomes obtained from the state-space technique. Lastly, by comparing the results of the simulation works and the experiments, it has been confirmed that this method is capable of precisely predicting the onset condition of free piston Stirling engines. Besides, the proposed approach could be used as a powerful tool to predict the behavior of various free piston Stirling engines regardless of whether they meet the onset condition or not.

Experimental results for structural design of Wire-and-Arc Additive Manufactured stainless steel members

Additive Manufacturing has recently gained great importance to produce metallic structural elements for civil engineering applications. While a lot of research effort has been focused on different technologies (such as Powder Bed Fusion), there is still quite limited knowledge concerning the structural response of Wire-and-Arc Additive Manufactured (WAAM) metallic elements, as very few experimental campaigns aimed at assessing their geometrical and mechanical properties have been carried out. The paper presents selected results of a wide experimental campaign focused on the assessment of the main geometrical and mechanical properties of Wire-and-Arc Additive Manufactured (WAAM) stainless steel material, carried out at the Topography and Structural Engineering Labs of University of Bologna. In detail, the focus is on the characterization of the surface irregularities by means of various measuring techniques and on the evaluation of the main material mechanical properties, including tensile and compressive strengths, Young's modulus and post elastic behavior. Tests results have been interpreted through statistical tools in order to derive mean values and gather information about the variability of both geometrical and mechanical parameters.

P839Lifetime cost-effectiveness of diagnostic artificial intelligence tool for evaluating individuals with stable chest pain. The co-operative ARTICA registry database

Abstract Background Non-invasive cardiac imaging testing has been often favored as an initial test for symptomatic patients with at least intermediate pre-test likelihood (pt-lk) of obstructive CAD. Despite this condition, uncertainty remains regarding the optimal testing strategies. It is known that intelligence applied with automatic decision support system (AI DSS) is able to correctly identify absence of significant CAD versus standard care (SD) in patients with stable chest pain (SCP). No evidence of long-term cost-effectiveness about AI DSS has been published in this setting. Purpose The aim is to determine the cost-effectiveness of AI DSS when applied to individuals without known CAD presenting with stable chest pain syndrome. Methods 1725 subjects, 982 males, age 61±12 years, with SCP were referred for clinical evaluation by human standard care (SD) and AI DSS administration during same day visit on a 2 years period. Exercise treadmill test (ETT), coronary tomographic angiography (CTA), invasive coronary angiography (ICA), stress echocardiography (SE)/gated myocardial perfusion scintigraphy (gMPS) and follow up/no tests (FNT) alone and combined strategies were analyzed. For the post-diagnosis follow up period of 16±3 months, we employed a Markov model based on 1-year cycle to account for outcomes for those correctly diagnosed with CAD. All subjects performed CTA to verify presence of CAD. CAD was defined as ≥70% stenosis in at least one major epicardial coronary artery vessels. Monte Carlo simulation was performed to derive mean values for costs and QALYs at different CAD prevalence of 15%, 50% and 80%. Results Data from ARTICA registry about lifelong costs based upon different diagnostic strategies in subjects with 15%, 50% and 80% CAD pt-lk are shown in Table. Lifelong costs related to strategies FNT (€) ETT-SE/gMPS-ICA (€) SE/gMPS-ICA (€) CTA-ICA (€) CTA-SE/gMPS-ICA pt-lk CAD 15% AI DSS 350 8,250 8,850 10,450 11,020 SD 1,015 11,100 12,715 12.215 12,215 pt-lk CAD 50% AI DSS 1,610 17,375 19,540 20,410 20,110 SD 1,855 19,650 21,340 22,950 22,115 pt-lk CAD 80% AI DSS 2,910 28,210 30,875 31,215 31,765 CD 4,110 32,715 34,815 35,755 35,660 Conclusion Data from ARTICA registry demonstrate that automatic use of AI DSS result in improved costs and enhanced effectiveness when compared with human SD in subjects with stable chest pain.

Spatial and temporal variability of snowfall over Greenland from CloudSat observations

Abstract. We use the CloudSat 2006–2016 data record to estimate snowfall over the Greenland Ice Sheet (GrIS). We first evaluate CloudSat snowfall retrievals with respect to remaining ground-clutter issues. Comparing CloudSat observations to the GrIS topography (obtained from airborne altimetry measurements during IceBridge) we find that at the edges of the GrIS spurious high-snowfall retrievals caused by ground clutter occasionally affect the operational snowfall product. After correcting for this effect, the height of the lowest valid CloudSat observation is about 1200 m above the local topography as defined by IceBridge. We then use ground-based millimeter wavelength cloud radar (MMCR) observations obtained from the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit, Greenland (ICECAPS) experiment to devise a simple, empirical correction to account for precipitation processes occurring between the height of the observed CloudSat reflectivities and the snowfall near the surface. Using the height-corrected, clutter-cleared CloudSat reflectivities we next evaluate various Z–S relationships in terms of snowfall accumulation at Summit through comparison with weekly stake field observations of snow accumulation available since 2007. Using a set of three Z–S relationships that best agree with the observed accumulation at Summit, we then calculate the annual cycle snowfall over the entire GrIS as well as over different drainage areas and compare the derived mean values and annual cycles of snowfall to ERA-Interim reanalysis. We find the annual mean snowfall over the GrIS inferred from CloudSat to be 34±7.5 cm yr−1 liquid equivalent (where the uncertainty is determined by the range in values between the three different Z–S relationships used). In comparison, the ERA-Interim reanalysis product only yields 30 cm yr−1 liquid equivalent snowfall, where the majority of the underestimation in the reanalysis appears to occur in the summer months over the higher GrIS and appears to be related to shallow precipitation events. Comparing all available estimates of snowfall accumulation at Summit Station, we find the annually averaged liquid equivalent snowfall from the stake field to be between 20 and 24 cm yr−1, depending on the assumed snowpack density and from CloudSat 23±4.5 cm yr−1. The annual cycle at Summit is generally similar between all data sources, with the exception of ERA-Interim reanalysis, which shows the aforementioned underestimation during summer months.

Transport Scaling of Dune Dimensions in Shallow Flows

AbstractDune dimensions in sand‐bedded rivers are often thought to scale with flow depth (h), with height (H) scaling as 1/6h and length (L) as 5h, even though substantial scatter about the relations has been observed. Transport stage has been shown to affect bedform geometry, but this control is often ignored in favor of depth scaling relations. Here, we use a series of flume experiments to systematically test controls on dune dimensions and variability. Experiments involved three sets of runs under five constant transport stages, ranging threshold to washout conditions, at three different flow depths. The mobile bed was repeatedly scanned during a 10‐hr equilibrium period to derive mean values and quantify the variability. The results show that dune‐depth scaling is not consistent because of a transport stage effect. Dune height increases with transport stage until a point when H decreases. Length remains nearly constant with transport stage until further increases in transport stage leads to lengthening. In general, dunes grow higher when significant bedload transport occurs but become flatter and longer in the presence of substantial suspension. Ultimately, dunes scale with transport stage, which is a function of slope, grain size, and h. The results are used to derive transport stage relations to guide predictions of dune dimensions in rivers and reconstructions of paleoflows based on dimensions estimated from cross strata. The relations incorporate the nonlinear response of dune dimensions with transport stage and provide metrics of uncertainty to include in predictions.

Mean values of derivatives of L-functions in function fields: III

AbstractIn this series of papers, we explore moments of derivatives of L-functions in function fields using classical analytic techniques such as character sums and approximate functional equation. The present paper is concerned with the study of mean values of derivatives of quadratic Dirichlet L-functions over function fields when the average is taken over monic and irreducible polynomials P in 𝔽q[T]. When the cardinality q of the ground field is fixed and the degree of P gets large, we obtain asymptotic formulas for the first moment of the first and the second derivative of this family of L-functions at the critical point. We also compute the full polynomial expansion in the asymptotic formulas for both mean values.

Mean values of derivatives of L-functions in function fields: II

This is the second part of our investigation of mean values of derivatives of L-functions in function fields. In this paper, specifically, we prove several mean values results for the derivatives of L-functions in function fields when the average is taken over all discriminants, i.e., over all monic polynomials of a prescribed degree in Fq[T]. We establish exact formulas for the mean value of the μ-th derivative of L-functions in function fields at the critical point and we compute a few particular examples.

Mean values of derivatives of L-functions in function fields: I

We investigate the first moment of the second derivative of quadratic Dirichlet L-functions over the rational function field. We establish an asymptotic formula when the cardinality of the finite field is fixed and the genus of the hyperelliptic curves associated to a family of Dirichlet L-functions over Fq(T) tends to infinity. As a more general result, we compute the full degree three polynomial in the asymptotic expansion of the first moment of the second derivative of this particular family of L-functions.

Assessment of Cavitation Erosion With a URANS Method

An assessment of the cavitation erosion risk by using a contemporary unsteady Reynolds-averaged Navier–Stokes (URANS) method in conjunction with a newly developed postprocessing procedure is made for an NACA0015 hydrofoil and an NACA0018-45 hydrofoil, without the necessity to compute the details of the actual collapses. This procedure is developed from detailed investigations on the flow over a hydrofoil. It is observed that the large-scale structures and typical unsteady dynamics predicted by the URANS method with the modified shear stress transport (SST) k-ω turbulence model are in fair agreement with the experimental observations. An erosion intensity function for the assessment of the risk of cavitation erosion on the surface of hydrofoils by using unsteady RANS simulations as input is proposed, based on the mean value of the time derivative of the local pressure that exceeds a certain threshold. A good correlation is found between the locations with a computed high erosion risk and the damage area observed from paint tests.

Making do with what we have: use your bootstraps

Key Points a jack knife is a pocket knife that is put to many tasks, because it's ready to hand. Often there could be a better tool for the job, such as a screwdriver, a scraper, or a can-opener, but these are not usually pocket items. In statistical terms, the expression implies making do with

Analysis of the Proximal Phalanx Size as a Guide for an Akin Closing Wedge Osteotomy

The Akin closing wedge osteotomy for correction of hallux valgus interphalangeus has experienced a resurgence in popularity. Commonly, the size of the osteotomy is visually judged intraoperatively. We present a means of performing the osteotomy more objectively. Radiographs of 101 feet were studied to derive mean values for dimensions of the hallux proximal phalanx in the general population. Based on these we calculated the size of osteotomy required for given corrections. The mean hallux width 5 mm distal to the apex of the articular surface differed between males and females. In males the mean width was 18 mm (95% CI 17.5 to 18.8) and in females 15 mm (95% CI 14.5 to 15.5). For a 10 degree correction, an osteotomy with a 3 mm base would be required. Although the Akin osteotomy dimensions are commonly estimated, a more objective method of planning the osteotomy is presented. The method can also be applied to any closing wedge osteotomy. We believe this method of the Akin osteotomy can improve the accuracy of the surgery.

Ca II TRIPLET SPECTROSCOPY OF SMALL MAGELLANIC CLOUD RED GIANTS. II. ABUNDANCES FOR A SAMPLE OF FIELD STARS

We have obtained metallicities of ~ 360 red giant stars distributed in 15 Small Magellanic Cloud (SMC) fields from near-infrared spectra covering the CaII triplet lines using the VLT + FORS2. The errors of the derived [Fe/H] values range from 0.09 to 0.35 dex per star, with a mean of 0.17 dex. The metallicity distribution of the whole sample shows a mean value of [Fe/H] = -1.00 +- 0.02, with a dispersion of 0.32 +- 0.01, in agreement with global mean [Fe/H] values found in previous studies. We find no evidence of a metallicity gradient in the SMC. In fact, on analysing the metallicity distribution of each field, we derived mean values of [Fe/H] = -0.99 +- 0.08 and [Fe/H] = -1.02 +- 0.07 for fields located closer and farther than 4 deg. from the center of the galaxy, respectively. In addition, there is a clear tendency for the field stars to be more metal-poor than the corresponding cluster they surround, independent of their positions in the galaxy and of the clusters' age. We argue that this most likely stems from the field stars being somewhat older and therefore somewhat more metal-poor than most of our clusters.