Calibration Constants Research Articles

Forecasting light-duty vehicle demand using alternative-specific constants for endogeneity correction versus calibration

We investigate parameter recovery and forecast accuracy implications of incorporating alternative-specific constants (ASCs) in the utility functions of vehicle choice models. We compare two methods of incorporating ASCs: (1) a maximum likelihood estimator that computes ASCs post-hoc as calibration constants (MLE-C) and (2) a generalized method of moments estimator that uses instrumental variables (GMM-IV) to correct for price endogeneity. In a synthetic study we observe significant coefficient bias with MLE-C when the price-ASC correlation (endogeneity) is large. GMM-IV successfully mitigates this bias given valid instruments but exacerbates the bias given invalid instruments. Despite greater coefficient bias, MLE-C yields better forecasts than GMM-IV with valid instruments in most of the cases examined, including most cases where the price-ASC correlation present in the estimation data is absent in the prediction data. In a market study of U.S. midsize sedan sales from 2002 – 2006 the GMM-IV model predicts the 1-year-forward market better, but the MLE-C model predicts the 5-year-forward market better. Including an ASC in predictions by any of the methods proposed improves share forecasts, and assuming that the ASC of each new vehicle matches that of its closest competitor vehicle yields the best long term forecasts. We find evidence that the instruments most frequently used in the automotive demand literature may be invalid.

A 225C Geothermal Logging Tool

Abstract Geothermal logging tools are difficult to develop due to sustained high temperature operation. Recent commercial component offerings are significantly altering the high temperature geothermal tool problem. This paper implements a new baseline geothermal tool circuit working with five 225C, SOI components. An example tool including up to four spinners (fluid flow measurement), four analog inputs (for pressure, temperature or other sensors), EEPROM storage (program and data), FSK logic (wireline data transmission), and a high-speed UART (tool communication). Field updates of code and calibration constants are supported. Further, this paper demonstrates how the tool electronics can be expanded for more complex applications such as a geothermal well logging camera.

Experimental Verification of the Hole Drilling Method with Inverse Layers Removing

The method for residual stress measurement is presented using through hole-drilling and investigation of the residual stresses relief with the help of incremental layers removing. Drilling the rosette hole from the opposite side - the inverse layers removing - have to be used for evaluation of residual stress near the back side of the object wall in cases when this surface is inaccessible for any hole-drilling instrument. The strain gauge rosette is installed on the opposite side of the drilled wall and a new mechanical task of incremental layers removal must be solved. The calibration constants for residual stress evaluation of HBM RY21 type rosette for this case were derived using numerical modeling by FEA and its experimental verification.

Independent Calibration of Water Vapor Raman Lidar by using Additional Elastic Measurements at Water Vapor Raman Wavelength

A new method for independent calibration of water vapor Raman lidar by using additional measurements of elastic signals at water vapor Raman wavelength was introduced. The water vapor mixing ratio calibration constant was derived from nitrogen mixing ratio calibration constant and Rayleigh to water vapor Raman backscattering cross section ratio. The nitrogen mixing ratio calibration constant with uncertainties of 1~2% can be determined from the nitrogen mixing ratio measurement in an aerosolfree zone in the upper troposphere with the additional elastic measurement and nitrogen Raman measurement, the Rayleigh to water vapor Raman backscattering cross section ratio can be calculated with uncertainties of about 8%, or can be determined experimentally with uncertainties of less than 5%. Using the experimental cross section ratio, a total uncertainty of the water vapor calibration less than 6% is possible to achieve. Because this calibration method utilizes actual lidar signals in nitrogen and water vapor detection channels, the calibration can fully capture lidar state changes.

Retrieval of precipitable water vapor using MFRSR and comparison with other multisensors over the semi-arid area of northwest China

Precipitable water vapor (PWV) was retrieved using direct solar irradiance at 938nm measured by a multifilter rotating shadowband radiometer (MFRSR) at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) located in the semi-arid area of northwest China from August 2007 to June 2010. Measurement also occurred at Zhangye, China, at the Atmosphere Radiation Measurements (ARM) Program's Ancillary Facility during the dust period from April to June 2008. The line-by-line radiative transfer model (LBLRTM) code combined with the HITRAN 2004 spectral database is used to model the water vapor spectral transmittance throughout the 938-nm spectral response of MFRSR in the retrieval algorithm. Gaussian fitting is proposed to determine the daily calibration constant at the top of atmosphere for a long-term series under an obvious annual change in solar radiation.PWV retrieved by MFRSR over SACOL shows that 90% of PWV values are smaller than 1.52cm, and PWV distribution has a seasonal variation, with maximum in summer and minimum in winter. The comparisons between MFRSR and other measurements show a better agreement between MFRSR and sunphotometer (AERONET's Cimel) PWV retrievals with relative bias of 2.9% and RMS difference of 9.1% than between MFRSR and microwave radiometer (MWR) with relative bias of 10% and RMS difference of 23% over SACOL, and an excellent agreement between MFRSR and sunphotometer with relative bias of 0.56% and RMS difference of 6.1% over Zhangye.To verify satellite PWV products over the semi-arid area of northwest China, the comparisons of PWV from MODIS and AIRS with MFRSR suggest that the agreement between satellite and MFRSR PWV retrievals is not as good as that between MFRSR and other ground-based instruments. MODIS appears to slightly underestimate PWV in a dry atmosphere but overestimate PWV in a moist atmosphere against MFRSR. A method is proposed to correct MODIS PWV products. AIRS PWV products relative to MFRSR show a systematic underestimation.

Evolution of ATLAS conditions data and its management for LHC Run-2

The ATLAS detector at the LHC consists of several sub-detector systems. Both data taking and Monte Carlo (MC) simulation rely on an accurate description of the detector conditions from every subsystem, such as calibration constants, different scenarios of pile-up and noise conditions, size and position of the beam spot, etc. In order to guarantee database availability for critical online applications during data-taking, two database systems, one for online access and another one for all other database access, have been implemented.The long shutdown period has provided the opportunity to review and improve the Run-1 system: revise workflows, include new and innovative monitoring and maintenance tools and implement a new database instance for Run-2 conditions data. The detector conditions are organized by tag identification strings and managed independently by the different sub-detector experts. The individual tags are then collected and associated into a global conditions tag, assuring synchronization of various sub-detector improvements. Furthermore, a new concept was introduced to maintain conditions over all different data run periods into a single tag, by using Interval of Validity (IOV) dependent detector conditions for the MC database as well. This allows on the fly preservation of past conditions for data and MC and assures their sustainability with software evolution.This paper presents an overview of the commissioning of the new database instance, improved tools and workflows, and summarizes the actions taken during the Run-2 commissioning phase in the beginning of 2015.

The LHCb Data Acquisition and High Level Trigger Processing Architecture

The LHCb experiment at the LHC accelerator at CERN collects collisions of particle bunches at 40 MHz. After a first level of hardware trigger with an output rate of 1 MHz, the physically interesting collisions are selected by running dedicated trigger algorithms in the High Level Trigger (HLT) computing farm. This farm consists of up to roughly 25000 CPU cores in roughly 1750 physical nodes each equipped with up to 4 TB local storage space. This work describes the LHCb online system with an emphasis on the developments implemented during the current long shutdown (LS1). We will elaborate the architecture to treble the available CPU power of the HLT farm and the technicalities to determine and verify precise calibration and alignment constants which are fed to the HLT event selection procedure. We will describe how the constants are fed into a two stage HLT event selection facility using extensively the local disk buffering capabilities on the worker nodes. With the installed disk buffers, the CPU resources can be used during periods of up to ten days without beams. These periods in the past accounted to more than 70% of the total time.

별 측광을 통한 야간 에어로졸의 광학적 두께 산출

In this study star photometry was applied to retrieve aerosol optical thickness (AOT) at night. The star photometry system consisted of small refractor, optical filters, CCD camera, and driving mount and was located in Suwon. The calibration constants were retrieved from the astronomical Langley method but standard deviations of these were more than 10% of the mean values. After the calibration the nighttime AOT was retrieved and cloud-screened in clear six days from 25 Nov. 2014 to 17 Jan. 2015. To estimate the quality of the measurements the nighttime AOT was combined with daytime AOT retrieved from sky-radiometer that was located in Seoul and 17 km away from the star photometry system. In spite of the uncertainty of the calibration constants and the spatial difference of two observation systems, the temporal changes of the nighttime AOT coincided with the daytime. The nighttime <TEX>${\AA}ngstr{\ddot{o}}m$</TEX> exponent was about 20% lower and more variable than the daytime because of the uncertainty of the calibration constants. If the calibration process is more precise, the combination of star and sun or sky photometry system can monitor the air pollution day and night constantly.

Technique for determining mass concentrations of aerosol fractions in the surface air from multifrequency lidar sounding data

A technique for determining mass concentrations of aerosol particles smaller than 1.0, 2.5, 10, and 30 µm in the surface air is suggested. The technique involves remote lidar sounding of the atmosphere at the wavelengths λ = 0.355, 0.532, 1.064, 2.13 µm, retrieval of the spectral and spatial distributions of the aerosol extinction coefficient from the lidar signals, and their conversion to the spatial distributions of the concentrations of aerosol fractions on the basis of regression relations between optical and microphysical aerosol parameters. To improve the accuracy and stability of the solution of a system of lidar equations, the calibration constants and lidar ratios at the wavelengths of the sounding radiation are chosen taking into account the multicollinearity of the spectral aerosol extinction coefficients, which is expressed in the form of a multiple regression equation. The regressions were derived within the World Meteorological Organization’s optical model of urban aerosol under wide variations in model parameters which characterize the particle size distribution and the complex refractive index of the aerosol matter. Numerical experiments on remote laser sounding of the mass concentration of aerosol fractions in the atmosphere have shown the robustness of the technique proposed.

Analysis of aerosol scattering properties measured by a nephelometer at a coastal-rural site in the Atlantic southwest of the Iberian Peninsula

Aerosol hemispherical scattering and the backscattering coefficients, σsp, σbsc, have been measured using a 3-wavelength (450, 550 and 700nm) integrating nephelometer over two years (January 2006–May 2008) in the coastal area of the Gulf of Cádiz, in the southwest of the Iberian Peninsula. These coefficients have been carefully analyzed starting with the impact of corrections on the measurements of σsp: i.e., drift calibration constants do not modify the mean value in our data series. However, the selection of dry data (with RH less than 50%) modifies substantially the number of data and the resulting mean value of σsp is now 14% lower, which is compensated when the angular truncation correction is applied. The characterization and features of σsp, σbsc, and the derived parameters αsp (alpha Ångström exponent) and b (the backscatter ratio) has been analyzed, as annual, seasonal and diurnal evolution. A general statistic based on hourly data gives mean values and standard deviation of σsp (500nm)=48±38Mm−1 with a median of 38Mm−1, and σbsc (500nm)=5.6±3.8Mm−1 with a median of 4.6Mm−1. Thus, these values show moderate-low values but with a large range of variation considering the existing measured values over the Iberian Peninsula. The median value of σsp (500nm) is an indicator that events of high aerosol burden are frequent presenting a substantial influence on the daily averages. The alpha Ångström exponent, αsp, derived from the pairs 450/700nm gives a mean value 1.35±0.54 with a median of 1.47 and with the most frequent value of 1.7, thus indicating the prevalence of medium size particles but with a significant influence of fine particles. The b ratio has the same value for mean and median, 0.12±0.02, showing a decrease with increasing values of σsp. Annual and daily cycles have been also analyzed showing the complex behaviour of the optical properties at this coastal site where cold and warn periods show very different characteristics. Besides, the daily cycle is strongly influenced by the breeze conditions. According to the information extracted from the σsp–αsp relationship this rural Atlantic site presents prevalence of mixed marine-continental aerosols but with significant influence of local anthropogenic sources. Desert dust particles were also discriminated which are not frequently reported in the data of “in situ” aerosols.

High accuracy thermal conductivity measurement of aqueous cryoprotective agents and semi-rigid biological tissues using a microfabricated thermal sensor.

An improved thermal-needle approach for accurate and fast measurement of thermal conductivity of aqueous and soft biomaterials was developed using microfabricated thermal conductivity sensors. This microscopic measuring device was comprehensively characterized at temperatures from 0 °C to 40 °C. Despite the previous belief, system calibration constant was observed to be highly temperature-dependent. Dynamic thermal conductivity response during cooling (40 °C to –40 °C) was observed using the miniaturized single tip sensor for various concentrations of CPAs, i.e., glycerol, ethylene glycol and dimethyl sulfoxide. Chicken breast, chicken skin, porcine limb, and bovine liver were assayed to investigate the effect of anatomical heterogeneity on thermal conductivity using the arrayed multi-tip sensor at 20 °C. Experimental results revealed distinctive differences in localized thermal conductivity, which suggests the use of approximated or constant property values is expected to bring about results with largely inflated uncertainties when investigating bio-heat transfer mechanisms and/or performing sophisticated thermal modeling with complex biological tissues. Overall, the presented micro thermal sensor with automated data analysis algorithm is a promising approach for direct thermal conductivity measurement of aqueous solutions and soft biomaterials and is of great value to cryopreservation of tissues, hyperthermia or cryogenic, and other thermal-based clinical diagnostics and treatments.

Reevaluated martian atmospheric mixing ratios from the mass spectrometer on the Curiosity rover

The Sample Analysis at Mars (SAM) instrument suite of the Mars Science Laboratory (MSL) Curiosity rover is a miniature geochemical laboratory designed to analyze martian atmospheric gases as well as volatiles released by pyrolysis of solid surface materials (Mahaffy et al., 2012). SAM began sampling the martian atmosphere to measure its chemical and isotopic composition shortly after Curiosity landed in Mars׳ Gale Crater in August 2012 (Mahaffy et al., 2013). Analytical methods and constants required for atmospheric measurements with SAM׳s quadrupole mass spectrometer (QMS) were provided in a previous contribution (Franz et al., 2014). Review of results obtained through application of these constants to repeated analyses over a full martian year and supporting studies with laboratory instruments offer new insights into QMS performance that allow refinement of the calibration constants and critical reassessment of their estimated uncertainties. This report describes the findings of these studies, provides updated calibration constants for atmospheric analyses with the SAM QMS, and compares volume mixing ratios for the martian atmosphere retrieved with the revised constants to those initially reported (Mahaffy et al., 2013). Sufficient confidence is enabled by the extended data set to support calculation of precise abundances for CO rather than an upper limit. Reanalysis of data acquired on mission sols 45 and 77 (at solar longitudes of 175° and 193°, respectively) with the revised constants leads to the following average volume mixing ratios: CO2 0.957(±0.016), N2 0.0203(±0.0003), Ar 0.0207(±0.0002), O2 1.73(±0.06)×10−3, CO 7.49(±0.026)×10−4.

FT-IR spectra of 18O-, and 13C-enriched CO2 in the ν3 region: High accuracy frequency calibration and spectroscopic constants for 16O12C18O, 18O12C18O, and 16O13C16O

In this report, we extend our Fourier transform infrared (FT-IR) spectroscopy measurements of CO2 in the ν3 region (2200–2450cm−1, 65–75THz) to the 18O-, and 13C-substituted isotopologues, using the JPL Bruker IFS-125HR Fourier Transform Spectrometer (JPL-FTS). High quality (S/N∼2000) spectra were obtained separately for each of the 18O-, and 13C-isotopically enriched samples. The absolute wavenumber accuracies were better than 3×10−6cm−1 (∼100kHz) for strong, isolated transitions, calibrated against the highest accuracy reported CO and 16O12C16O (626) frequency measurements. The JPL-FTS performance and calibration procedure is shown to be reliable and consistent, achievable through vigorous maintenance of the optical alignment and regular monitoring of its instrumental line shape function. Effective spectroscopic constant fits of the 00011←00001 fundamental bands for 16O12C18O (628), 18O12C18O (828), and 16O13C16O (636) were obtained with RMS residuals of 2.9×10−6cm−1, 2.8×10−6cm−1, and 2.9×10−6cm−1, respectively. The observed bands encompassed 79 lines over the Jmax range of P67/R67, 47 lines over P70/R62, and 60 lines over P70/R70 for 628, 828, and 636, respectively. These results complement our recent work on the 17O-enriched isotopologues (Elliott et al., 2014), providing additional high-quality frequency measurements for atmospheric remote sensing applications.

Extension and evaluation of a model for automatic drainage solution management in tomato crops grown in semi-closed hydroponic systems

In the present paper, a model previously developed to simulate the course of Na+ accumulation in closed hydroponic systems as a function of plant water consumption was further extended so as to be operative also in semi-closed and open systems, and evaluated in two experiments with hydroponic tomato. In the first experiment, the efficiency of the model to predict the Na+ concentration in the recycled solution not only in a closed but also in an open and a semi-closed system was comparably tested. In the second experiment, the model was applied in two semi-closed systems differing in the target drainage fraction (0.3 or 0.6) and an open system used as control. The model proved to be functionally efficient in restricting nutrient and water discharge in semi-closed hydroponic systems, in comparison with open systems, as well as in mitigating salt accumulation in the root zone, in comparison with constantly closed systems. The semi-closed system did not improve yield in comparison with the closed system or water use efficiency in comparison with the open system because the Na concentration in the irrigation water used in the present study (2mM) was relatively low, but improved appreciably the nutrient use efficiency in comparison with the open system. However, the model failed to accurately predict the course of Na+ accumulation both in the closed and the semi-closed hydroponic system when applied in a different cultivar (‘Belladona’) than that used for model calibration (‘Formula’). This failure is ascribed to marked differences in Na+ exclusion efficiency between these two cultivars. Thus, when using this model in semi-closed hydroponic tomato crops, different calibration constants are needed for cultivars with strong genotypic differences in Na+ exclusion efficiency. The model performance in a crop of the tomato cultivar used for its calibration (i.e. ‘Formula’) was acceptable for commercial crops, regardless of the applied drainage fraction. On-line monitoring of the actual drainage fraction instead of the use of a mean target value might further improve the ability of the model to predict the actual Na concentration in the root zone of semi-closed tomato crops.

Pressure-dependent calibration of the OH and HO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; channels of a FAGE HO&amp;lt;sub&amp;gt;x&amp;lt;/sub&amp;gt; instrument using the Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC)

Abstract. The calibration of field instruments used to measure concentrations of OH and HO2 worldwide has traditionally relied on a single method utilising the photolysis of water vapour in air in a flow tube at atmospheric pressure. Here the calibration of two FAGE (fluorescence assay by gaseous expansion) apparatuses designed for HOx (OH and HO2) measurements have been investigated as a function of external pressure using two different laser systems. The conventional method of generating known concentrations of HOx from H2O vapour photolysis in a turbulent flow tube impinging just outside the FAGE sample inlet has been used to study instrument sensitivity as a function of internal fluorescence cell pressure (1.8–3.8 mbar). An increase in the calibration constants CHO and CHO2 with pressure was observed, and an empirical linear regression of the data was used to describe the trends, with ΔCHO = (17 ± 11) % and ΔCHO2 = (31.6 ± 4.4)% increase per millibar air (uncertainties quoted to 2σ). Presented here are the first direct measurements of the FAGE calibration constants as a function of external pressure (440–1000 mbar) in a controlled environment using the University of Leeds HIRAC chamber (Highly Instrumented Reactor for Atmospheric Chemistry). Two methods were used: the temporal decay of hydrocarbons for calibration of OH, and the kinetics of the second-order recombination of HO2 for HO2 calibrations. Over comparable conditions for the FAGE cell, the two alternative methods are in good agreement with the conventional method, with the average ratio of calibration factors (conventional : alternative) across the entire pressure range, COH(conv)/COH(alt) = 1.19 ± 0.26 and CHO2(conv)/CHO2(alt) = 0.96 ± 0.18 (2σ). These alternative calibration methods currently have comparable systematic uncertainties to the conventional method: ~ 28% and ~ 41% for the alternative OH and HO2 calibration methods respectively compared to 35% for the H2O vapour photolysis method; ways in which these can be reduced in the future are discussed. The good agreement between the very different methods of calibration leads to increased confidence in HOx field measurements and particularly in aircraft-based HOx measurements, where there are substantial variations in external pressure, and assumptions are made regarding loss rates on inlets as a function of pressure.

Calibration study of the X-T relation for the BESIII drift chamber**Supported by National Natural Science Foundation of China (11205184, 11205182, 11121092, 11179020) and Joint Funds of National Natural Science Foundation of China (U1232201)

Offline calibration plays an important role in BESIII offline data processing. In order to achieve good spatial and momentum resolution, it is necessary to implement high precision offline calibration for the BESIII drift chamber. This paper studies the time-to-distance relations, which are important calibration constants for track reconstruction. The parameterization of the time-to-distance relation, studies of left-right asymmetry and studies of variation with entrance angle are performed. The impact of dead channels on the time-to-distance relation is given special attention in order to reduce the shift in measured momentum for tracks passing near dead cells. Finally we present the resolutions for barrel Bhabha events (|cosθ|<0.8) from a J/ψ data set taken in 2012. The average spatial resolution is 123 μm and the momentum resolution for 1.548 GeV/c Bhabha tracks is 11.9 MeV/c.

Polarization analysis and corrections of different telescopes in polarization lidar

Telescopes in polarization lidar often modify the input polarization of the return signal, such that the telescope may significantly impact the depolarization estimates of aerosol and introduce error to the polarization lidar measurements. The error cannot be corrected by a traditional calibration constant. We present a method to correct the polarization effect of the telescope. We analyze the polarization effect of a telescope on the basis of the Mueller formalism, and introduce an algorithm for correcting the depolarization parameter of aerosol. A Newton telescope and a Cassegrain telescope are often chosen as the receiver in lidar. Their polarization models are established, and the Mueller matrices are calculated. The components of these matrices are dependent on wavelength, incident angle of the incoming light, and surface properties. The polarization impact of the telescope in lidar can be calibrated by a parameter, and the effects of different telescopes are discussed. The polarization crosstalk induced by the Newton telescope is obvious. The depolarization parameters change greatly with coating and wavelength, and they are calculated and presented. Whereas the crosstalk of a Cassegrain telescope is much smaller, the error can reach the level of 10−3 and can be negligible. The method presented in this paper could also be upgraded by taking into account all of the optical devices instead of only the telescope.

Annular shape silver lined proportional counter for on-line pulsed neutron yield measurement

An annular shape silver lined proportional counter is developed to measure pulsed neutron radiation. The detector has 314mm overall length and 235mm overall diameter. The central cavity of 150mm diameter and 200mm length is used for placing the neutron source. Because of annular shape the detector covers >3π solid angle of the source. The detector has all welded construction. The detector is developed in two halves for easy mounting and demounting. Each half is an independent detector. Both the halves together give single neutron pulse calibration constant of 4.5×104 neutrons/shot count. The detector operates in proportional mode which gives enhanced working conditions in terms of dead time and operating range compared to Geiger Muller based neutron detectors.

Transfer method to calibrate the normalized radiance for a CE318 Sun/sky radiometer

A transfer method is introduced to derive the normalized radiance for CE318 Sun/sky radiometer using viewing solid angles and extraterrestrial calibration constants. The new transfer method has a good consistency at different parts of the sky scanning. Error analysis suggests that the uncertainty of the transferred method is about 2.0%–2.4%. The normalized radiances are used as input of the aerosol inversion to test the performance of the new transfer method. The residuals of the inversion (e.g., difference between fitted and measured radiance) are chosen as the index of the radiance calibration accuracy. Analyses of one year’s measurements in Beijing suggest an average sky residual of 3.3% for almucantar scanning (while 3.7% for the AERONET method), which suggest a better accuracy of the transfer method when used in aerosol retrieval.

Effect of liner design on performance of a HICOM® mill over the predicted liner life cycle

The life cycle performance of two alternative mill liner designs have been predicted using DEM with a calibrated wear model and using a geometric mill liner evolution method. The HICOM 110 mill was used as a case study to demonstrate how such a model can be used to help understand the full life cycle performance of a mill. This mill was chosen because of the availability of validated calibration constants for the wear model for this mill. The comparison of the evolution sequences shows that initial small differences in wear profiles for different lifters can lead to quote a different life cycle behaviour — both for the erosion behaviour of the liner and for the performance of the mill. They also demonstrate that the wear predicted for the new liner does not necessarily well reflect the whole of life wear process as the feedback between the wear and flow can strongly influence the liner life cycle.