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To measure soil water content (or soil matric suction) in thin layers of about 30mm, conventional gypsum blocks are not suitable. To carry out the task, mini-gypsum blocks were constructed using plaster of Paris in an innovative fashion. A power relationship was found between the soil water content and the mini-gypsum blocks’ readings in kΩ. The calibration results showed that readings of mini-gypsum blocks were sensitive to temperature. A normalized resistance deviation method was adopted to compensate for the effect of temperature on the sensor readings. After calibration, the high coefficient of determination obtained ensured the use of the mini-gypsum blocks for further experiments.

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Aims: Modeling precipitation-runoff processes and forecasting river flow are an essential step in floods management and controlling, designing water structures in watersheds and droughts management.
Materials & Methods: In the present research, WetSpa distributed hydrological model was applied to simulate river flow in Ziarat watershed of Golestan Province. This basin has an area of 95 km2 and it has an average height of 1760 m above sea level. As a distributed, continuous, and physical model, WetSpa is characterized with daily or hourly time series which accounts for processes of precipitation, runoff, and evapotranspiration contexts. The model parameters include distributive and global parameters. To run model, daily data on flow, precipitation, temperature, and evaporation for years 2008–2016 were considered for calibration and validation.
Findings: The results of simulation showed a relatively good compatibility between calculated and measured hydrograph at the basin outlet. According to Nash-Sutcliffe model for calibration periodic model, efficiency coefficient estimated daily hydrographs and maximum flow rate by 57.32% and 84.11% accuracy, respectively. However, given Nash–Sutcliffe coefficient which was equaled to −385.39 and −209.06 for low and high flow, respectively, validation results are not acceptable which it can be attributed to water withdrawal and diversion dam for water harvesting before gauging stations in outle.
Conclusion: Given the calibration results, WetSpa model has great efficiency under high flow circumstances compared to low flow mainly due to model weakness in low flow estimation but as a whole model simulated total flow with acceptable accuracy.

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Residual stress measurement is one of the most interesting research areas in experimental mechanics. Residual stress is introduced to material due to plastic deformation of parts and can be one of the most effective parameters on design and operation of parts. ASTM E837-01 standard studies residual stress determination in parts by hole drilling method and represent calibration coefficients for flat sheets with constant stress profile. However, there is no certain standard on the residual stress measurement by Incremental Hole Drilling Method (IHDM) which is the subject of this study. IHDM can obtain stress profile by using two modified stress calibration coefficients. In this article, the stress calibration coefficients have been extracted for incremental hole drilling by using finite element analysis (FEA). FEA contains both biaxial tension test and pure shear test which a hole has been drilled step by step in the parts by removing elements and the strains changes were determined at three strain gauge positions on the surface. At last, the calibration coefficients are determined for each step and the accuracy of coefficients have been verified by a set of experimental test and a FE analysis. The experimental test contains four-point bending of an AA5056 flat aluminum sheet. The numerical analysis contains four-point bending of a flat sheet. In both cases, the stress profile can be determined easily by using analytical equations. Average analytical stress in each increment has been calculated and compared with the result of numerical incremental hole drilling method. The comparisons show that numerical and experimental results have no significant differences in first six steps but in the last four steps show an increasing errors due to the change in stress profile and hole geometry. Results presents that the calibration coefficients have suitable accuracy in stress profile determination.

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Abstract: Car-Following models are integral parts of capacity analysis, safety research, traffic simulation, and developing advanced vehicle control systems. During the past six decades, various car following models have been developed. GHR is the most well-known stimulus based model, in which the stimulus is the relative velocity of vehicles. In this research, timeto- collision (TTC), as the stimulus, is proposed as a substitute for relative velocity in the GHR model. GHR model is calibrated based on the comprehensive and detailed data gathered in the NGSIM project on I-80 freeway. The Results of GHR model calibration based on the data obtained for the two stimuli indicated that coefficient of determination (R2) increased from 0.233 in the base model to 0.638 in the proposed model. In all, the results indicated that the application of TTC as the stimulus in the GHR model would improve the model's outcome.

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An extended octagonal ring (EOR) transducer was designed and developed to measure forces inside the compression chamber of a large square baler in different directions. The transducer was calibrated by applying forces in three directions simultaneously and independently. The sensor revealed excellent linearity along with small cross sensitivities. Horizontal and vertical primary sensitivities of the sensor were 1,479.7 and 1387.8 μVkN-1V-1, while horizontal and vertical cross sensitivities were 0.64 and 2.85% of the sensor primary sensitivities, respectively. The sensor was used to measure the forces inside the compression chamber of a large square baler in different directions.

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This paper presents the closed-form calibration procedure of a 5-Dof Mitsubishi robot. In this method only the joint angle information is required. But due to the limitation of the robot degrees of freedom it is not possible to attach the end-effector of the robot directly to the ground; however, we can use a bar with two ball end joints for this purpose. By doing this, the robot can move freely in space. The most limiting factor of the closed-loop calibration of robot is that we cannot measure the non-moving joints, and we have to use other joint to estimate the motion of these joints. A novel approach to estimate the non-moving degrees of freedom are presented in the paper that can be extended to other robots. Experimental results validate the proposed method and the deviation of the joint parameters compared with the nominal values of the robot parameters delivered in the catalogue is very limited and are in an acceptable ranges.

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Fluctuations in fiscal policy affect monetary policy and the central bank, because the government’s general budget is highly dependent on oil prices and its fluctuations. Therefore, this paper designs a New Keynesian model for Iran with nominal rigidities (prices and wages) and analyzes the impact of technology, oil price, government spending and money supply shocks on macroeconomic variables (inflation, output) in economy of Iran. The data in this article are related to the fixed prices in the year 2004 and run annually from 1966 to 2008 on a per capita basis. Having logarithms taken, the variables are de-traded through Hodrick - Prescott filter. The final model equations are linearized around the steady state and using Uhlig (1999) approach, accidental equations are also linearized and are specified as space state pattern in Matlab software. Finally, the calibration of parameters are assessed, variables are simulated and compared with real data. The results show that the recommended model can simulate the impact of shocks on macroeconomic variables. It also shows that inflation rises in response to all shocks except that of technology. As the figures show, it is also revealed that non-oil output increases in response to technology, oil price, government spending and money supply.

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Ramsey model is one of the most important basic models to study intertemporal resource allocation. This model is derived from microeconomic optimal principle so it has a key role in macroeconomics with micro foundations. Hence, in many economic researches it is considered as a reference theory. Application of this model in economy of Iran will provide an appropriate theorem framework for explaining empirical facts of the Iranian economy and will introduce a new approach to researchers. The main idea of this study is generalizing Ramsey model through including terms of trade and its calibration in the economy of Iran. For this purpose first, the model is explained. Then, the first order condition is derived and mathematical optimal path of variables is solved.  Finally, the model is calibrated by GAMS package for economy of Iran in time period (2006-2036). The results indicate that there is a feasible solution for model and the optimal path of variables can be observed. The optimal path of Gross National Production and Consumption are increasing but the optimal path of capital stock and investment is primarily increasing then decreasing. In the final section of this paper a sensitivity analysis is presented. Some scenarios are designed for the important parameters of model like time preferences rate, intertemporal substitution elasticity of consumption, labour growth rate and output elasticity of capital. Sensitivity analysis shows that output elasticity of capital and labour growth rate increased the social welfare and shifted optimal path of variables upward. But time preferences rate and intertemporal substitution elasticity of consumption had inverse effect on social welfare and optimal path of variables.

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The aim of this paper is to analyze the sensor errors in measurement while drilling (MWD) instrument used in directional drilling operations. The MWD consist of three orthogonal accelerometers, three orthogonal magnetometers and one temperature sensor. The system formulation is achieved through the system analysis and functional consideration. The obtained formulation is validated and verified by comparing the results obtained from measurements and simulations. The accelerometers calibration, to estimate bias factors, scale factors and non-orthogonal factors of sensors, is done using optimal non-linear Newton Raphson algorithm by considering the high temperature calibration coefficients. The accuracy of the experimental results, obtained from several measurement while drilling systems in Iranian national oil drilling company shows the effectiveness of the approach.
 
 

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The Hargreaves-Samani (HS) equation, which estimates reference evapotranspiration (ET0) using only temperature as input, should be most suitable for ET0 prediction based on weather forecasting data. In the current study, the HS equation is calibrated with daily ET0 by the Penman-Monteith equation, and is evaluated to check the possibility of predicting daily ET0 based on weather forecast data. The HS equation is likely to overestimate daily ET0 in the humid regions of China. Coefficients a and c are calculated as 0.00138 and 0.5736 according to local calibration. The calibrated HS equation performs considerably better than the original one. The proposed equation could be an alternative and effective solution for predicting daily ET0 using public weather forecast data as inputs. The error of daily ET0 prediction increases with the increase in the error of daily temperature range (TR) or daily mean temperature (Tmean). This error is likely to be more sensitive to the error in TR than in the Tmean. Ensuring that TR errors are less than 2°C is necessary for perfect estimations of ET0 based on public weather forecast data using the calibrated HS equation.

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The measurement of hydrodynamic loads on submerged bodies is one of the principal uses of water tunnels. Due to the limitations of the water tunnel, an accurate force balance is necessary. This paper describes the design, fabrication and calibration of a new six-component force moment balance system for measuring the forces and moments acting on the model, in static and dynamic water tunnel testing. A balanced team performed many areas for designing balance system such as structural design, balance technology, design of calibration mechanism, balance calibration etc. A six-component balance, ability to measure the three elements of force and three components of moment simultaneously and instantly on cavitating and non- cavitating models in a water tunnel. The concept used in the balance design is the bending beam and the strain gage principle. The electrical signals are proportional to the forces applied to the model. By considering the relationship between the applied force and the balance’s output signal and by using the calibration models, the forces and moments exerted on the model in the water tunnel can measure directly. For calibrate multi component balance, a new six-degree of freedom calibration rig designed and constructed. The system is designed based on applicability of formal experimental design techniques, using gravity for balance loading and balance position and alignment relative to gravity. The six-component balance was calibrated by this rig. The standard error between the measured values and the values obtained from calibration model is less than 0.1 percent of maximum loading was achieved.

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Cracks due to manufacturing processes or in-service applications can propagate and cause failure in structures. Therefore, it is of interest to find a suitable fracture assessment method for predicting crack initiation. Main approaches for fracture assessment of structures are global approach and local approach. In the global approach, it is assumed resistance against fracture can be measured by a critical values of a far from crack tip parameter like K or J. In this study, Beremin model of local approach is used for predicting brittle fracture which studies stress and strain fields at the crack tip. The model introduces unknown parameters which have to be calibrated using experimental fracture data. The purpose of this study is evaluating of conventional calibration methods of local approach parameters using the experimental brittle fracture data of three point bending specimens, determining limitations, and finally presenting a new calibration method to produce suitable parameters for predicting brittle fracture of the specimens by using local approach to fracture. This study shows that conventional calibration method using experimental fracture data of three point bending specimens has limitation in some cases. Also, by introducing location parameter of Weibull distribution as a stress triaxiality criteria in Beremin model, a new rational method for predicting brittle fracture of the three point bending specimens with different constraints is presented.

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Failure of mechanical structures may be caused by presence of some defects like cracks. These defects are generally created due to manufacturing processes or in-service applications. Failures due to cleavage fracture usually lead to catastrophic effects, thus studies of such failures are important. Main approaches for fracture assessment of structures are global approach (classical fracture mechanics) and local approach. In the previously presented models of local approach, unknown parameters are introduced which have to be calibrated using experimental fracture data. Despite of existing different calibration methods, obtaining suitable parameters for predicting brittle fracture based on local approach, has been limited in some cases. The purpose of this study is presenting a rational method for predicting brittle fracture in specimens of different shapes to transform it into full scale cases. In this paper, by considering the location parameter of Weibull distribution as a stress triaxiality criteria and modifying the Beremin model, predicting brittle fracture in specimens of different shapes are studied. Also, independence of the parameters from their shapes is shown and eventually a linear relation between location parameter of Weibull distribution and triaxiality factor for the material is presented.

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In this paper, the incremental hole-drilling method is used to measure experimentally with accuracy non-uniform residual stresses in each ply of fiber metal laminate (FML) composites. Integral method was used for the approximation of residual stress. This method, considered a constant and uniform residual stress analysis at each hole-drilling depth increment. At the first, finite element method is used to calculation of the calibration coefficients matrix of the incremental hole drilling process. The calibration coefficients matrix determined by a finite element analysis can be used directly in the experiment. Calibration coefficients matrix used to relate the measured strain relaxation field with the existing residual stresses prior to the hole-drilling process. Also, for the experimental determination, released strains induced by high speed drilling process on FML composites with a stacking sequence of [AL/02/902]S have been quantified. At the end, the experimental measurements are compared with the theoretical predictions of the classical laminate theory. The good agreements between the experimental and theoretical results show that, incremental hole-drilling technique can be improved to be successfully applied for measuring non-uniform residual stresses in FML composites.

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Interest rate Ad valorem tariffs are considered as the most prominent trade tools extensively used in the framework of Spatial Equilibrium Models (SEMs) to analyze agricultural and food trade policies around the world. However the results obtained from such models have been criticized because of their inadequacy in producing any observed data within the base period. Hence a positive spatial and temporal trade model which incorporates ad valorem tariffs was developed throughout the ongoing study. The calibrated model helps researchers to perform a substantially flawless empirical trade study in the real world. A numerical example is finally presented at the end of the article to justify the findings of the model, and to compare welfare analysis of the calibrated vs. the uncalibrated model.  

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Accurate measurement of unsteady pressure fluctuations along a surface requires experimental set up with high spacing resolution and high frequency domain. Therefore, in recent decades extensive studies have been conducted on remote microphone approach. In this method, instead of using flash mounted sensors, they installed remotely and connected to the model surface through one or several continuously connected tubes. Surface pressure fluctuations will travel within the tubing in the form of sound waves and they will be measured when passing over the remote pressure sensor, mounted perpendicular to the tubing. In the present study, an analytical solution of sound waves propagation inside the rigid tubes is used for modelling of the remote microphone system and to investigate the effects of its parameters on dynamic response. In order to verify the accuracy of proposed modeling, the dynamic response of a typical remote microphone has been obtained through experimental calibration. Comparing the analytical and experimental results indicates high accuracy of the analytical modeling. Results show that changes in tubing diameter leads to occurrence of resonance and creating harmonics in two frequency regions. The amplitude of low-frequency harmonics depends on the length of the damping duct and decreases with increasing of its length. Instead, the amplitude and frequency of high-frequency harmonics depend on the length of the first tube and they decrease with the increase of first tube length. Also, Increase of the first and second tube lengths lead to an increase in phase of dynamic response of the remote microphone system.

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Texture analyzer is one of the important tools for analyzing and evaluating texture properties including hardness, softness, extensibility, tightness, fragility, adhesiveness, adhesion, compressibility, flexibility, shearability, elasticity, gel strength and springiness In this research, a texture analyzer was designed which, based on software and data processing ideas, while increasing the accuracy of performance and measurements, it provided calibration capabilities to make the output data close to real data  . The main features of the texture analyzer are the ability to carry out the test in controlled temperature and humidity to analyze the texture parameters in order to reduce error in regions with different temperature and humidity. The results of the tests show that by carefully calibrating the calibration process and designing the calibration filter, the accuracy of the analyzer's performance is improved to 0.05% of the read value. Also, using the micro-stapling algorithm and the use of the screw mechanism, the movement of the jaw is precisely less than 0.005 mm and the speed of 0.1 millimeter per second is controllable. All of these features, along with the USB connection with any personal computer, will be able to communicate directly with the EXCEL program, and save and simplify data analysis under the EXCEL program. The results of the tests show that there is no statistically significant difference between the relative humidity of the texture analyzer and the relative humidity for each sample (p <0.05). Texture hardness of different samples of biscuits containing resistant starch was evaluated by commercial (C) and designed (D) instrument and there was no significant difference between the hardness of the texture obtained from both devices.

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Mathematical models have the potential to provide a cost-effective, objective, and flexible approach to assessing management decisions, particularly when these decisions are strategic alternatives. In some instances, mathematical model is the only means available for evaluating and testing alternatives.  However, in order for this potential to be realized, models must be valid for the application and must provide results that are credible and reliable. The process of ensuring validity, credibility, and reliability typically consists of three elements: verification, validation, and calibration. Model verification, validation and calibration are essential tasks for the development of the models that can be used to make predictions with quantified confidence. Quantifying the confidence and predictive accuracy of model provides the decision-maker with the information necessary for making high-consequence decisions. There appears to be little uniformity in the definition of each of these three process elements. There also appears to be a lack of consensus among model developers and model users, regarding the actions required to carry out each process element and the division of responsibilities between the two groups. This paper attempts to provide mathematical model developers and users with a framework for verification, validation and calibration of these models. Furthermore, each process element is clearly defined as is the role of model developers and model users. In view of the increasingly important role that models play in the evaluation of alternatives, and in view of the significant levels of effort required to conduct these evaluations, it is important that a systematic procedure for the verification, validation and calibration of mathematical models be clearly defined and understood by both model developers and model users.

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Acceptable estimation of reference Evapotranspiration (ET₀) values by the Penman-Monteith FAO (PM FAO) equation requires accurate solar radiation (R_s) data. R_s values could be estimated using the Angstrom’s radiation model. The aim of this study was to determine the a_s and b_s coefficient (as Angstrom’s parameters) for the Ardabil plain as an arid and cold region. Angstrom’s radiation model and PM FAO equation were calibrated for the study area, by optimizing the a_s and b_s parameter using Generalized Reduced Gradient (GRG) method. Measured R_sdata were collected from the Ardabil Synoptic Station and measured ET₀ data were determined using three lysimeters that were installed at the Hangar Research Station. Calibrated results showed that optimized a_s and b_s values were 0.117 and 0.384, respectively. Compared to the original models, errors including RMSE, AE and RE values were decreased and fitted parameters including R² and regression line slope (m) were improved in the calibrated models. The GMER values for the original models showed that Angstrom’s radiation model overestimated the R_s values and PM FAO equation underestimated the ET₀ values. Locally calibrated models estimated R_s and ET₀ values better than the original one. Nash-Sutcliffe efficiency coefficient (NSE) values proved that R_s and ET₀ estimation by the original models were not satisfactory, but were acceptable in the case of the calibrated models. However, calibration of Angstrom’s radiation model and PM FAO equation is necessary for each region.
 

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Deriving the accurate dynamic model of robots is pivotal for robot design, control, calibration, and fault detection. To derive an accurate dynamic model of robots, all the terms affecting the robotchr('39')s dynamics are necessary to be considered, and the dynamic parameters of the robot must be identified with appropriate physical insight. In this paper, first, the kinematics of the ARAS-Diamond spherical parallel robot, which has been developed for vitreoretinal ophthalmic surgery, are investigated, then by presenting a formulation based on the principle of virtual work, a linear form of robot dynamics is derived, and the obtained results are validated in SimMechanics environment. Furthermore, other terms affecting the robot dynamics are modeled, and by using the linear regression form of the robot dynamics with the required physical bounds on the parameters, the identification process is accomplished adopting the least-squares method with appropriate physical consistency. Finally, by using the criteria of the normalized root mean squared error (NRMSE) and using different trajectories, the accuracy of the identified dynamic parameters is evaluated. The experimental validation results demonstrate a good fitness for the actuator torques (about 75 percent),  and a positive mass matrix in the entire workspace, which allows us to design the common model-based controllers such as the computer torque method, for precise control of the robot in vitreoretinal ophthalmic surgery.