Time Correction Factor Research Articles

An improved creep correction factor for footings on sand using macro-element simulations

In many settlement prediction methods, the creep settlement of shallow foundations on sand is either disregarded or accounted for using time correction factors that lack a reliable basis. These existing settlement correction factors for creep have mainly been derived from a restricted number of long-term settlement measurements and do not consider the influence of factors such as the load level, rate of load application and properties of the soil below the foundation. In this study, a newly proposed one-dimensional elasto-viscoplastic macro-element was used to investigate the factors influencing the time-dependent behaviour of shallow foundations on sand. The safety factor of the foundation, the creep characteristics of the soils and the duration of load application were found to have important effects on the post-construction settlement development. The simulation results were used to develop an enhanced settlement correction factor for creep, which takes into account the identified factors. The improved settlement correction factor was found to be comparable to existing ones when the safety factor of the foundation is 3. The effectiveness of the proposed settlement correction factor is demonstrated using creep settlement measurements from one field footing test and two case histories.

Research on the Coordination Suppression Strategy of Neutral Point Potential and Common Mode Voltage for NPC Three-Level Inverter

A Neutral Point Clamped (NPC) type three-level inverter has the advantages of a low switch voltage and a high-quality output waveform. However, there are inherent problems, such as neutral point potential asymmetry and common mode interferences, which easily affect the symmetry of the three-phase output voltage and the safe operation of the inverter. Firstly, according to the different modulation degrees, the fluctuation of midpoint potential can be suppressed by adding an action time correction factor to the traditional space vector pulse-width (SVPWM) modulation strategy and virtual space vector pulse-width (VSVPWM) modulation strategy, respectively. Secondly, considering the suppression of common mode voltage, a new virtual space vector pulse-width (NVSVPWM) modulation strategy is proposed, which uses a set of new vector synthesis methods. Finally, the simulation and experiment prove that the NVSVPWM strategy with an action time correction factor can suppress the fluctuation of the neutral point potential and common mode voltage at the same time, and the effect is significant.

Compensating Method of Equivalent Current Sources of LSI-Core Macromodel Considering Voltage Fluctuations in On-Chip Power Distribution Network

Electro-magnetic compatibility (EMC) macromodels of a large-scale integrated (LSI) circuit core have been proposed to predict conducted RF emission and power integrity issues not only on a printed circuit board but also inside an LSI. They are equivalent circuit models that consist of lumped element impedance blocks of an LSI-core and equivalent current sources expressing internal switching activities. In conventional macromodeling, equivalent current sources have been extracted under ideal power supply conditions, i.e., with constant supply voltage. However, there exists transient supply voltage fluctuations in an actual on-chip power distribution network (PDN), and the operating current and its equivalent current sources are expected to vary with such fluctuations. Such issues with transient supply voltage fluctuations have not been extensively investigated. We propose a method of compensating the equivalent current sources of a macromodel by introducing amplitude and time correction factors, taking into account the voltage fluctuations in an on-chip PDN.

A new novel-1-step shutdown dose rate method combining benefits from the rigorous-2-step and direct-1-step methods

A new method for the calculation of Shutdown Dose Rates (SDDR) has been developed, the Novel-1-Step (N1S) method. The new method retains the benefits of only requiring a single radiation transport calculation, as in the use of the direct-1-step (D1S) method, while removing the need for pre-calculations to determine dominant nuclides and time correction factors. The N1S method uses a time dependent source and decay data for all nuclides. When reactions in the transport occur leading to unstable daughter nuclide, the correct contribution of photon radiation from all the decay products of a nuclide are calculated with no need for additional external activation calculations. Weights of these decay photons are calculated for each decay time of interest and are analytically determined based on the solutions to the Bateman equations.The N1S method has been implemented into MCNP and preliminary verification calculations performed. These calculations included the FNG ITER shutdown dose rate benchmark and the ITER SDDR cross comparison. For the FNG ITER SDDR benchmark the N1S method showed good agreement, within experimental error, for the first campaign apart from the first decay time where a C/E value of 1.34 was obtained. This overestimation was shown to be due to the decay of 64Cu inside the copper cup of the neutron generator. For the second campaign the N1S method showed an under prediction of up to 20% at short decay times and an over prediction up to 20% at longer decay times. These times are dominated by 56Mn and 58Co respectively and it is likely the difference is due to under and over predictions in the reaction rates leading to these nuclides. The ITER cross comparison showed good agreement between the N1S method and MCR2S (and by association other D1S and R2S codes). Differences seen in the results were shown to be due to difference in the calculated reaction rates using EAF2010, TENDL2019 and FENDL3.2.

Fuzzy-Swarm Intelligence-Based Short-Term Load Forecasting Model as a Solution to Power Quality Issues Existing in Microgrid System

Load demand is highly stochastic and uncertain. This is because it was highly influenced by a number of variables like load type, weather conditions, time of day, the seasonality factor, economic constraints, and other randomness effects. The loads are categorized as holiday loads (national and religious), weekdays, and weekend days. The nonlinearity and uncertain characteristics of electrical load in a microgrid are one of the major sources of power quality problems in a microgrid system, and they can be handled using an accurate load forecast model. The fuzzy load prediction model can effectively handle these nonlinearity and uncertainty characteristics to have an accurate load forecast, but the main challenge with this model is its inability to accommodate a large volume of historical load and weather information when the membership function of the input and output fuzzy variables and the number of the fuzzy rules are tremendous. The swarm intelligence load forecast model based on particle swarm optimization algorithms can improve the limitations of the fuzzy system and increase its forecasting performance. The parameters of time, temperature, historical load, and error correction factors are considered as the Fuzzy and Fuzzy-PSO model input variables, while the forecasted industrial load is the only output variable. The Gaussian membership function is considered for both the input and output fuzzy variables. A 3-year historical hourly load data of an Ethiopian industrial system is used to train and validate both prediction models. The mean absolute percentage error (MAPE) is used to evaluate the performance of these prediction models. The Fuzzy-PSO load prediction model shows results that have superior performance to the fuzzy-alone load prediction results.

Development of an Elongated Ellipsoid Heat Source Model to Reduce Computation Time for Directed Energy Deposition Process

Directed Energy Deposition (DED) Additive Manufacturing process for metallic parts are becoming increasingly popular and widely accepted due to their potential of fabricating parts of large dimensions. The complex thermal cycles obtained due to the process physics results in accumulation of residual stress and distortion. However, to accurately model metal deposition heat transfer for large parts, numerical model leads to impractical computation time. In this work, a 3D transient finite element model with Quiet/Active element activation is developed for modeling metal deposition heat transfer analysis of DED process. To accurately model moving heat source, Goldak’s double ellipsoid model is implemented with small enough simulation time increment such that laser moves a distance of its radius over the course of each increment. Considering thin build-wall of Stainless Steel 316L fabricated with different process parameters, numerical results obtained with COMSOL 5.6 Multi-Physics software are successfully validated with experiment temperature data recorded at the substrate during the fabrication of 20 layers. To reduce the computation time, elongated ellipsoid heat input model that averages the heat source over its entire path is implemented. It has been found that by taking such large time increments, numerical model gives inaccurate results. Therefore, the track is divided into several sub-tracks, each of which is applied in one simulation increment. In this work, an investigation is done to find out the correct simulation time increment or sub-track size that leads to reduction in computation time (5–10 times) but still yields sufficiently accurate results (below 10% of relative error on temperature). Also, a Correction factor is introduced that further reduces computation error of elongated heat source. Finally, a new correlation is also established in finding out the correct time increment size and correction factor value to reduce the computation time yielding accurate results.

A one–dimensional elasto-viscoplastic macro-element model for creep analysis of shallow foundations on sand

Footings on sand can exhibit considerable long-term creep settlement. However, most settlement prediction methods account for creep by using either a reduced long-term equivalent sand stiffness or applying an arbitrary time correction factor. In this paper, a novel elasto-viscoplastic macro-element model for shallow foundations on sand under vertical loading is developed that provides a simple and efficient tool for footing settlement prediction explicitly accounting for creep in a realistic manner. By incorporating an isotach relationship postulated for the load-settlement behaviour of shallow foundations on sand, the macro-element is constructed based on the non-stationary flow surface theory and the time effect is incorporated using visco-plasticity. The proposed model, which requires only three input parameters, is shown to be capable of satisfactorily reproducing the load-settlement responses of footings tested in the field and in the geotechnical centrifuge at typical working loads. The proposed model can also reproduce effects seen in practice such as post-creep stiffening and settlements induced by unload-reload cycles.

Time reversal damage localization in concrete based on two-dimensional meso-scale modeling

In this article, a damage localization method in concrete materials based on time reversal theory and meso-scale finite element simulation considering random heterogeneous properties is developed. In this article, concrete is regarded as a multiphase composite material consisting of cement mortar matrix, coarse aggregates, and interface transition zones. Compared to other methods, which assume that concrete is homogeneous, the meso-scale model considers the intricacies of concrete inhomogeneity and can therefore better characterize the interaction between stress waves and internal structures of concrete material. Through the meso-scale method, acoustic phenomena including reflection, transmission, and diffraction among internal structures of concrete can be modeled. Furthermore, a novel time reversal based, damage imaging method is developed using the envelope of the refocused damage scattering signal to monitor the health condition of concrete. The scattered signal received by each sensor is time reversed and reemitted via numerical computation. To decrease the dispersion effect, the autocorrelation function of the refocused signals is computed to generate an image of the estimated damage. A time correction factor is introduced to decrease the influence of the elongated wave packet. Numerical and experimental results indicate that the proposed damage imaging method can locate damage with high spatial resolution in heterogeneous concrete material. Moreover, owing to the meso-scale modeling, the propagation of high-frequency stress waves in concrete can be analyzed more accurately.

Are workers on board vessels involved with chemicals from treated ballast water sufficiently protected? – A decadal perspective and risk assessment

Ballast Water Managements Systems (BWMS) installed on vessels may use Active Substances (AS) to inactivate organisms. This paper provides new insights in the global issue of noxious Disinfection By-Products (DBP) produced with primarily oxidant-based BWMS, and the risk assessment for workers, including port State control officers, while performing tasks on a vessel that involve exposure to treated ballast water. The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection – Ballast Water Working Group (GESAMP-BWWG) plays a role in the certification process of BWMS that make use of AS evaluating potential negative effects. All BWMS that passed GESAMP-BWWG Final Approval until mid 2019 were analyzed providing an overview of chemicals in the treated ballast water before and after neutralization. The ballast tank cleaning scenario, the sampling scenario, and the ballast tank inspection scenario all showed elevated human health risks using the Derived Minimal Effect Levels approach. The most critical exposure occurs in the ballast tank cleaning scenario through the inhalation of volatile DBP, such as tribromomethane. This substance may cause acute effects such as headache, dizziness and also has carcinogenic properties. The two risk reducing options available in the GESAMP-BWWG Tier 2 calculations were compared, one being mitigation measures such as protective gloves and coveralls, the other option is taking into account a time correction factor. The results showed that the trihalomethanes in air are most problematic, however, there is a possibility that the calculated values may be overestimated as generally worst case assumptions were used.

Forecasting slope deformation field using correlated grey model updated with time correction factor and background value optimization

Developing precise models to characterize the slope instability mechanism quantitatively and predict slope movement behavior accurately remains a challenge in engineering geology. This paper updates the traditional GM (1,1) grey model to the TGM (1,1,p,q) grey model by adding a nonlinear time correction factor and optimizing the weighting coefficients of the background values using Genetic Algorithm. Furthermore, the TGM (1,1,p,q) has been updated to the TGM (1,n,p,q) correlated grey model by using a multivariate model of multiple monitoring boreholes to characterize the integrated deformation field. Taking the Majiagou reservoir bank landslide as an example, the time-series data of five monitoring boreholes were compared with their predicted values. The results show that the prediction accuracy of the updated grey model TGM (1,1,p,q) is acceptable, and the accuracy of the correlated updated grey model TGM (1,n,p,q) is much better. TGM (1,n,p,q) holds the potential of attaining a satisfactory prediction accuracy for the landslide deformation field forecasting.

Independent assessment of source transit time for the BEBIG SagiNova® high dose rate brachytherapy afterloader

Introduction: The dwell time and transit time components contribute to the overall delivered dose to patients in high dose rate (HDR) brachytherapy treatments. The transit time results from source entry and exit as well as source movements between dwell positions. It depends on various parameters such as the source speed profile, source indexer distance to dwell position, and step size. Usually brachytherapy treatment planning systems do not apply a correction for transit time and the afterloader unit itself adjusts the final dwell times taking account of the transit time. The independent verification of transit time for each HDR afterloader is recommended before clinical use. Some published reports have used a video camera and/or stopwatch to perform this task. To the best of our knowledge, there is no published report of transit time measurement for the recently released BEBIG SagiNova® HDR afterloader unit. The goal of this study is to independently evaluate the corrected source transit time of this afterloader unit without using a video camera or stopwatch. Materials and Methods: The assessed unit was a newly installed SagiNova® 60Co HDR afteroloader (software version 1.2.4; Eckert & Ziegler BEBIG GmbH). A dosimetric method was used. The measurements were performed using a previously commissioned PTW source check4п (type 33005) well- type ionization chamber and UNIDOS E® electrometer. A 30 cm plastic needle and a 100 cm transfer tube were used to accurately place the source at the point of maximum response (‘sweet spot’) of the well chamber. Plans were generated using SagiPlan version 2.0 to irradiate the well chamber for dwell times of 3, 5, 10, 15, 20, 30, 40, 60, and 120 s. All the measurements were repeated three times. The transit time following its correction by the afterloader software were assessed using the ESTRO-recommended approach of obtaining transit time correction factors and another strategy established for teletherapy sources. The results obtained using the two strategies were also compared. Results: For the measured setup, the transit time was 0.7 s using both methods. The mean ESTRO transit time correction factor was 0.93 (range 0.88 to 0.99 for dwell times of 3 to 120 s). Conclusion: This work demonstrates an accurate dosimetry-based method to measure source transit time during the commissioning step of HDR BT afteroloaders, using a practical approach and available standard equipment. It also shows the consistency of the results between the two dosimetric methods of obtaining source transit time. The results suggest that the afterloader software correction does not completely eliminate this effect, which results in slightly longer irradiation times.

Prediction of Come‐Up Time Correction Factor for Heat Processing of Food in Containers Using Come‐Up Heating Medium Temperatures

AbstractA general formula was derived for predicting come‐up time correction factors needed to accurately estimate the values of food in containers subjected to time variable heating medium temperatures during the come‐up period of heat sterilization process. It would be applicable to any food with any mode of heat transfer regardless to container geometry because it was derived from empirical formulas containing and values, which were developed for food temperature estimation. From this general formula, a new procedure was developed for calculating the come‐up time correction factors by using experimental come‐up heating medium temperatures. In this investigation, however, come‐up time correction factors were calculated by the developed procedure using time‐temperature data obtained from mathematical functions representing assumed come‐up heating medium temperature history curves. By comparing the results with those calculated from theoretical formulas, which were derived by substituting these mathematical functions for the general formula, it was found that the come‐up time correction factors could be accurately calculated by the developed procedure.Practical ApplicationsThe and values, which are accurately estimated from the heating curve, may be used for determining (thermal diffusivity) and (surface heat transfer coefficient/thermal conductivity) necessary to heat penetration simulation for heat conduction food in containers, which are approximated by cylinders, slabs, or spheres.

Comparison of Experiments to Computational Fluid Dynamics Models for Mixing Using Dual Opposing Jets in Tanks With and Without Internal Obstructions

This paper documents testing methods, statistical data analysis, and a comparison of experimental results to computational fluid dynamics (CFD) models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an 8-foot-diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors, such as turbulence, pump fluctuations, and eddies, required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations—or scatter—occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times was shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy and determined statistical correction factors that can be applied to CFD models and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending using a pump with dual opposing jets, which recirculate fluids in the tank to promote blending when fluids are added to the tank. In all, 85 tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full-scale, liquid radioactive waste storage tank. Also, different jet diameters and different horizontal orientations of the jets were investigated with respect to blending. Two types of blending tests were performed. The first set of 81 tests blended small quantities of tracer fluids into solution. Data from these tests were statistically evaluated to determine blending times for the addition of tracer solution to tanks, and blending times were successfully compared to computational fluid dynamics (CFD) models. The second set of four tests blended bulk quantities of solutions of different density and viscosity. For example, in one test, a quarter tank of water was added to three quarters of a tank of a more viscous salt solution. In this case, the blending process was noted to significantly change due to stratification of fluids and blending times increased substantially. However, CFD models for stratification and the variability of blending times for different density fluids were not pursued, and further research is recommended in the area of blending bulk quantities of fluids. All in all, testing showed that CFD models can be effectively applied if statistically validated through experimental testing, but, in the absence of experimental validation, CFD models can be extremely misleading as a basis for design and operation decisions.

Incorporating Time-Corrected Life Cycle Greenhouse Gas Emissions in Vehicle Regulations

Beginning with model year 2012, light-duty vehicles sold in the U.S. are subject to new rules that regulate tailpipe greenhouse gas (GHG) emissions based on grams of CO(2)-equivalent per mile (gCO(2)e/mi). However, improvements in vehicle technology, lower-carbon fuels, and improvements in GHG accounting practices which account for distortions related to emissions timing all contribute to shifting a greater portion of life cycle emissions away from the vehicle use phase and toward the vehicle production phase. This article proposes methods for calculating time-corrected life cycle emissions intensity on a gCO(2)e/mi basis and explores whether regulating only tailpipe CO(2) could lead to an undesirable regulatory outcome, where technologies and vehicle architectures with higher life cycle GHGs are favored over technologies with lower life cycle emissions but with higher tailpipe GHG emissions. Two life cycle GHG assessments for future vehicles are presented in addition to time correction factors for production and end-of-life GHG emissions. Results demonstrate that, based on the vehicle designs considered here, there is a potential for favoring vehicles with higher life cycle emissions if only tailpipe emissions are regulated; moreover, the application of time correction factors amplifies the importance of production emissions and the potential for a perverse outcome.

Evaluation of Some Solar Models with a New Software Package

Everybody uses solar energy in one form or the other. It is a source of life to human beings, plants and animals. Indeed, sun is fuel of life. In this article, we briefly discuss the usefulness of solar energy and developed a computer software package, SolarSoft for the evaluation of Bowen and evaporative fraction models. With a decade data from four Meteorological sites in Nigeria, we estimated two solar laws of Wien and Stefan-Boltzmann. Besides, we evaluated local standard time meridian, local solar time, and time correction factor, Equation of time, as well as declination, elevation, maximum elevation for Northern and Southern hemispheres, Azimuth, Zenith and hour angles. A dynamic class library was developed for all the models, which other developers will find salutary in their works. SolarSoft functions to specifications. Photovoltaic system Engineers will benefit tremendously using our package to obtain not only elevation angle, but also its maximum values for photovoltaic system simulation. Virtually every Atmospheric Scientists will benefit from the use of SolarSoft as an efficient, flexible and accurate research tool. General Terms Software, Solar

The ENEA-IRP thoron calibration facility

To check the consistency of a (220)Rn measurement, performed by passive alpha track detector (ATD), the use of an accurate (220)Rn exposure calibration facility is mandatory. The ENEA Radon Service developed a new CR-39 ATD-Tn, coupled to the radon ATD-Rn and, to assess its sensitivity, had to design a small calibration facility, which has been recently modified to improve the spatial homogeneity exposure conditions inside the chamber, to get a continuous monitoring of the (220)Rn concentration and to reduce radon contamination. A better knowledge of the circuit response allowed selecting the best-operating conditions and how to regulate the thoron concentration. The active thoron monitor has been changed to serve as a continuous sampling and measuring device rather than a grab one; particular care has been devoted to assess the (216)Po losses on the device's inner surfaces and to evaluate the chamber transit time correction factor.

A Radiobiological Analysis of Multicenter Data for Postoperative Keloid Radiotherapy

To identify factors significantly affecting recurrence rates after postoperative external beam radiotherapy (XRT) of keloids, and to delineate any radiation dose response and effects of radiation dose per fraction. A comprehensive literature review was performed to compile a database of 2,515 resected keloids (36.9% earlobe). Postoperative XRT was 45- to 100-kV X-rays in 27.0% or 120- to 250-kV X-rays in 11.1%, Co-60 in 1.9%, Sr-90 in 4.7%, 1.5- to 9-MeV electrons in 26.5%, and no XRT in 28.8%. In the 1,791 irradiated patients, the median radiation parameters were as follows: total dose, 15 Gy (range, 6-30 Gy); dose per fraction, 5.0 Gy (range, 2-15 Gy); fractions, 3 (range, 1-10); and time, 7 days (range, 0-33 days). Multivariate stepwise logistic regression correlated decreased keloid recurrence with earlobe location (p = 1.98E-10; odds ratio, 0.34), biologically effective dose (p = 1.01E-27), and treatment with electron beam or Co-60 vs. other techniques (p = 0.0014; odds ratio, 0.72). Different radiobiological models calculated values of α/β = 1.12 to 2.86 (mean, 2.08) and time (repopulation) correction factors for biologically effective dose from 0.98 to 2.13 Gy per day (mean, 1.34) starting 10 days after surgery. Different models (with α/β = 2.08) predicted that doses needed for 90% and 95% control with 3 fractions of postoperative electron beam were 16.0 to 16.2 Gy and 18.3 to 19.2 Gy, respectively, in less than 10 days for earlobe keloids and 21.5 to 22.2 Gy and 23.4 to 24.8 Gy, respectively, in less than 10 days for other sites. Postoperative keloid radiotherapy requires moderately high doses and optimal technique to be effective. The relatively low α/β ratio indicates that radiotherapy with a limited number of fractions and high doses per fraction is the best strategy.

Random coincidence summing of gamma rays and dead time count loss corrections in HPGe-detector based gamma ray spectrometry

Random coincidence summing of gamma rays and dead time count losses are a potential source of errors in gamma ray spectrometry. In this work, the magnitudes of count rate losses due to the random coincidence summing and dead time effect, alongwith corresponding corrections, have been studied. Experiments were performed in two independent gamma ray spectroscopic laboratories (referred as LAB-A & LAB-B), utilizing low activity reference nuclides 65 Zn and 60 Co. The low activity reference radionuclide 65 Zn was produced by using 10 MW nuclear reactor (PARR-1) at PINSTECH for use in one Lab. The gamma ray spectra were acquired using HPGe-detector based gamma ray spectrometers at fixed shaping times of the amplifier and positions of the reference nuclides. The MCA dead times of the spectrometers were varied to incur the count rate losses to the peaks of interest. Three procedures were adopted to determine the dead time and random summing correction factors. The corrections to count rate data measured at LAB-A, which represented a maximum of 46% losses, were obtained within standard deviation figures of 2.9%, 1.3% and 0.4% and in LAB-B case the losses of 41%, were corrected to within 1.8%, 1.1% and 0.6%, respectively with the described three procedures. The best-achieved precision (difference between the measured count rate with negligible dead time and the average of corrected count rates) in the case of LAB-A and LAB-B were within 1 x 10 ―3 and 2 x 10 ―2 %. The new procedure on the basis of fitting function is also evolved as a result of this study, which has produced the highly consistent results. The experimental data from the literature are also incorporated in this study for comparison purposes.

Accounting for Time-Dependent Effects in Biofuel Life Cycle Greenhouse Gas Emissions Calculations

This paper proposes a time correction factor (TCF) to properly account for the timing of land use change-derived greenhouse gas emissions in the biofuels life cycle. Land use change emissions occur at the outset of biofuel feedstock production, and are typically amortized over an assumed time horizon to assign the burdens of land use change to multiple generations of feedstock crops. Greenhouse gas intensity calculations amortize emissions by dividing them equally over a time horizon, overlooking the fact that the effect of a greenhouse gas increases with the time it remains in the atmosphere. The TCF is calculated based on the relative climate change effect of an emission occurring at the outset of biofuel feedstock cultivation versus one amortized over a time horizon. For time horizons between 10 and 50 years, the TCF varies between 1.7 and 1.8 for carbon dioxide emissions, indicating that the actual climate change effect of an emission is 70-80% higher than the effect of its amortized values. The TCF has broad relevance for correcting the treatment of emissions timing in other life cycle assessment applications, such as emissions from capital investments for production systems or manufacturing emissions for renewable energy technologies.

Design and air–water calibration of a waveguide connector for TDR measurements of soil electric permittivity in stony soils

Time Domain Reflectometry (TDR) is one of the most widely used methods for measuring soil water content. TDR determines water content by measuring the apparent relative electric permittivity of the soil or relative permittivity ( ɛ ra ), which is directly related to soil water. For TDR waveguides used in stony soils, the connection between the Trase TDR probe head (Model Trase System 6051X1, Soilmoisture Equipment Co., USA) and the waveguides can be difficult because of the lack of parallelism between the waveguides. Such a lack of parallelism is caused by the occurrence of a large amount of rock fragments in the soil profile, which produces air gaps and compression zones around the waveguides causing errors in the estimation of ɛ ra when the Trase TDR probe head is connected to the waveguides. For this reason, a new type of flexible connector that minimises the existing problems has been designed. The signal travel time correction factor t 0 , which accounts for signal travel in the designed flexible waveguide connector, and the electrical path length of the waveguide L e have been calibrated. In addition, a software for analysing the waveform obtained using the Trase TDR system has been developed. The calibration results were considered to be good and the sensitivity of soil water content values to the estimates of t 0 was low. Higher values of soil apparent electric permittivity were found when the waveform was measured with the flexible connector than when the Trase connector was used; mainly with the waveguides 150 mm long and when the soil water content in the superficial layer was high.