Absolute Value Of Difference Research Articles

IgA rheumatoid factor in rheumatoid arthritis.

Rheumatoid factor (RF) is a well-established marker for the diagnosis and classification of rheumatoid arthritis (RA). Most studies evaluated IgM RF or isotype-nonspecific total RF assays. We evaluated the added value of IgA RF in this context. An international sample cohort consisting of samples from 398 RA patients and 1073 controls was tested for IgA RF with 3 commercial assays. For all RA patients and 100 controls essential clinical and serological data for ACR/EULAR classification were available. The sensitivity of IgA RF for diagnosing RA was lower than the sensitivity of IgM RF. Differences in numerical values between IgA RF assays were observed. With all assays, the highest IgA RF values were found inpatients with primary Sjögren's syndrome. Double positivity for IgM RF and IgA RF had a higher specificity for RA than either IgM RF or IgA RF. The sensitivity of double positivity was lower than the sensitivity of either IgA RF or IgM RF. Single positivity for IgA RF was at least as prevalent in controls than in RA patients. Adding IgA RF to IgM RF and anti-citrullinated protein antibodies (ACPA) did not affect RA classification. However, combined positivity for IgA RF, IgM RF and IgG ACPA had a higher specificity and lower sensitivity for RA classification than positivity for either of the antibodies. IgA RF showed a lower sensitivity than IgM RF. Combining IgA RF with IgM RF and ACPA did not improve sensitivity of RA classification. Combined positivity (IgA-RF/IgM-RF/ACPA) increased specificity.

A head-to-head comparison between Guardian Connect and FreeStyle Libre systems and an evaluation of user acceptability of sensors in patients with type 1 diabetes.

A user-calibrated real-time continuous glucose monitoring (rt-CGM) system is compared to a factory-calibrated flash glucose monitoring (FGM) system and assessed in terms of accuracy and acceptability in patients with type 1 diabetes (T1D). Ten participants with T1D were enroled from a specialist diabetes centre in Singapore and provided with the Guardian Connect with Enlite Sensor (Medtronic, Northridge, CA, USA) and first-generation Freestyle Libre System (Abbott Diabetes Care, Witney, UK), worn simultaneously. Participants had to check capillary blood glucose four times per day. At the end of week 1 and week 2, participants returned for data download and were given a user evaluation survey. Accuracy evaluation between Guardian Connect and Freestyle Libre includes the overall mean absolute relative difference value (9.7±11.0% vs. 17.5±10.9%), Clarke Error Grid zones A+B (98.6% vs. 98.1%), sensitivity (78.9% vs. 63.4%), and specificity (93.4% vs. 81.0%). Notably, time below range (<3.9mmol/L) was 10.5% for FGM versus 2% for rt-CGM. From the evaluation survey, 90% of participants perceived rt-CGM to be accurate versus 40% for FGM, although the majority found both devices to be easy to use, educational, and useful in improving glycaemic control. However, due to the cost of sensors, only 30% were keen to use either device for continuous monitoring. Although rt-CGM was superior to FGM in terms of accuracy, the value of glucose trends in both devices is still useful in diabetes self-management. Patients and clinicians may consider either technology depending on their requirements.

PENGARUH STRUKTUR MODAL, KEBIJAKAN UTANG, DAN UMUR PERUSAHAAN TERHADAP NILAI PERUSAHAAN DENGAN UKURAN PERUSAHAAN SEBAGAI VARIABEL MODERASI

This research aims to test the influence of capital structure, debt policy, and the age of companies on the value of property and real estate sector companies listed on the Indonesia Stock Exchange in 2016-2020. The study also tested whether the size of companies was able to moderate their respective relationships between capital structure, debt policy, and the age of the company to the company's value. The study used a quantitative approach with a comparative causal type. The population in this study is all property and real estate sector companies listed on the Indonesia Stock Exchange in 2016-2020. Sampling techniques using purposive sampling. The data used in this study is secondary data accessed through the IDX website. Data analysis uses multiple regression analysis to hypothesize capital structure, debt policy, and corporate age, as well as an analysis of the value of absolute difference for capital structure, debt policy, and the age of the company to the company's value with the size of the company as a moderation variable. The results of this study showed that the structure of capital and age of the company had a positive and significant effect on the value of the company, while the debt policy had a negative and significant effect on the value of the company. The moderation variable is the size of the company being able to moderate the relationship between the capital structure and debt policy to the value of the company, but not able to moderate the relationship between the age of the company to the value of the company.

FAKTOR-FAKTOR YANG MEMPENGARUHI KUALITAS LAPORAN KEUANGAN PEMERINTAH DAERAH DENGAN KOMITMEN ORGANISASI SEBAGAI PEMODERASI

This study aims to show the effect of human resource competence, utilization of information technology and managerial control on the quality of the financial reports of the Takalar Regency Government with organizational commitment as moderating. This research uses quantitative research with descriptive paradigm. The data used is primary data. The research population is the Regional Government of Takalar Regency. The sampling technique used was purposive sampling with a total sample of 85 people. Data analysis used multiple linear regression analysis and moderated regression analysis with absolute difference value approach. The results of this study indicate that the competence of human resources, utilization of information technology and managerial control have a significant positive effect on the quality of financial reports. Organizational commitment is not able to moderate the variables of human resource competence and the use of information technology on the quality of financial reports, but organizational commitment is able to moderate the managerial control variables on the quality of financial reports. This research is practically expected to be an input to improve the quality of financial reports by increasing KSDM, information technology and managerial control. And theoretically it is expected to add to the accounting research literature related to LKPD.

Speed of Sound Measurements of Binary Mixtures of Hydrofluorocarbons [Pentafluoroethane (R-125), 1,1-Difluoroethane (R-152a), or 1,1,1,2,3,3,3-Heptafluoropropane (R-227ea)] with Hydrofluoroolefins [2,3,3,3-Tetrafluoropropene (R-1234yf) or trans-1,3,3,3-Tetrafluoropropene (R-1234ze(E))

Speed of sound data measured using a dual-path pulse-echo instrument are reported for three binary refrigerant mixtures, R-125/1234yf, R-1234yf/152a, and R-1234ze(E)/227ea, at compositions of (0.33/0.67) and (0.67/0.33) mole fraction. The speed of sound was studied at temperatures ranging from 230 K to 345 K from pressures slightly above the bubble point curve up to 20 MPa for the mixtures containing R-1234yf and 49 MPa for the R-1234ze(E)/227ea mixtures. The relative combined expanded speed of sound uncertainty ranged from 0.039 % to 0.317 % with a mean uncertainty over all state points of less than 0.10 %. The reported data are compared to the most recent mixture models in REFPROP for each blend studied. Comparisons of available mixture models for the R-125/1234yf and R-1234yf/152a blends exhibit average absolute deviation values ranging from 0.10 % to 0.27 %, and the average absolute deviations for R-1234ze(E)/227ea blends range from 0.62 % to 0.94 %. The comparisons show that only minor adjustments are required to the R-125/1234yf and R-1234yf/152a mixture models to represent the speed of sound data within its uncertainty. However, significant adjustments are needed to improve the current mixture models for the R-1234ze(E)/227ea blend. Deficiencies with the R-1234ze(E)/227ea mixture model are not unexpected since it (1) utilizes a pure-fluid EOS R-1234ze(E) that has been shown to inaccurately represent R-1234ze(E) speed of sound values and (2) uses binary interaction parameters for the chemically similar mixture of R-1234yf/227ea.

Prediction of critical properties and boiling point of fluorine/chlorine-containing refrigerants

In this work, molecular groups were used as the descriptor of molecular structures, combining with multi-layer perceptron algorithm to establish the prediction models of boiling point, critical temperature and critical pressure of fluorine/chlorine-containing refrigerants. The absolute average deviation values of the three prediction models between the calculated and experimental data in total datasets are 2.93%, 3.13% and 4.46%, respectively. Furthermore, in order to understand how the group features influence the prediction of properties, an interpretable method, Shapely Additive exPlanation (SHAP) was employed to interpret the proposed models, which computed the contributions of group features, and verified that the present models effectively building the relationship between the molecular groups and thermophyical properties.

Fused-Lasso Regularized Cholesky Factors of Large Nonstationary Covariance Matrices of Replicated Time Series

The smoothness of subdiagonals of the Cholesky factor of large covariance matrices is closely related to the degree of nonstationarity of autoregressive models for time series data. Heuristically, one expects for nearly stationary covariance matrix entries in each subdiagonal of the Cholesky factor of its inverse to be approximately the same in the sense that the sum of the absolute values of successive differences is small. Statistically, such smoothness is achieved by regularizing each subdiagonal using fused-type lasso penalties. We rely on the standard Cholesky factor as the new parameter within a regularized normal likelihood setup which guarantees: (a) joint convexity of the likelihood function, (b) strict convexity of the likelihood function restricted to each subdiagonal even when n < p, and (c) positive-definiteness of the estimated covariance matrix. A block coordinate descent algorithm, where each block is a subdiagonal, is proposed, and its convergence is established under mild conditions. Lack of decoupling of the penalized likelihood function into a sum of functions involving individual subdiagonals gives rise to some computational challenges and advantages relative to two recent algorithms for sparse estimation of the Cholesky factor, which decouple row-wise. Simulation results and real data analysis show the scope and good performance of the proposed methodology. Software for our method is freely available in R language. Supplementary materials for this article are available online.

Comparison of different registration methods in cone-beam computed tomography for breast boost radiation therapy

Abstract Introduction: The aim of this study is to compare patient geometrical uncertainties in the treatment of breast boost three-dimensional conformal radiation therapy (3D-CRT) considering both manual alignment and automatic different registration methods in cone-beam computed tomography (CBCT). Methods: A total of 85 patients were chosen for this study. A total of 254 registrations of CBCT vs planning computed tomography (CT) were retrospectively performed using automatic registration algorithms from Elekta XVI system (Clipbox and Mask) to detect patient setup uncertainties. All CBCTs were also matched manually by three health professionals. Mean shift values obtained with manual registration performed by health professionals were used as reference. Absolute value of difference between automatic algorithm shifts and reference values shifts was collected for each enrolled patient considering the three different spatial directions (x, y ,z), and the magnitude was calculated (δm for Mask and δc for Clipbox). Results: Data analysis showed a significant difference in δm and δc. t-Test statistics showed a high difference between Mask and Clipbox, in particular mean δm = (1.3 ± 0.1) mm and δc = (3.3 ± 1.2) mm (p-value &lt;0.0001). Mask algorithm was performed in a very similar way with respect to the reference alignment, and the differences between these two procedures were of the order of 1 mm. Clipbox algorithm showed larger differences with manual registration. Conclusions: These results suggest that the Mask algorithm may be the optimal choice for patient setup verification in clinical practice for breast boost treatment in 3D-CRT.

A comparative study of seismic tomography models of the Chinese continental lithosphere

The Chinese mainland is subject to complicated plate interactions that give rise to its complex structure and tectonics. While several seismic velocity models have been developed for the Chinese mainland, apparent discrepancies exist and, so far, little effort has been made to evaluate their reliability and consistency. Such evaluations are important not only for the application and interpretation of model results but also for future model improvement. To address this problem, here we compare five published shear-wave velocity models with a focus on model consistency. The five models were derived from different datasets and methods (i.e., body waves, surface waves from earthquakes, surface waves from noise interferometry, and full waves) and interpolated into uniform horizontal grids (0.5° × 0.5°) with vertical sampling points at 5 km, 10 km, and then 20 km intervals to a depth of 160 km below the surface, from which we constructed an averaged model (AM) as a common reference for comparative study. We compare both the absolute velocity values and perturbation patterns of these models. Our comparisons show that the models have large (> 4%) differences in absolute values, and these differences are independent of data coverage and model resolution. The perturbation patterns of the models also show large differences, although some of the models show a high degree of consistency within certain depth ranges. The observed inconsistencies may reflect limited model resolution but, more importantly, systematic differences in the datasets and methods employed. Thus, despite several seismic models being published for this region, there is significant room for improvement. In particular, the inconsistencies in both data and methodologies need to be resolved in future research. Finally, we constructed a merged model (ChinaM-S1.0) that incorporates the more robust features of the five published models. As the existing models are constrained by different datasets and methods, the merged model serves as a new type of reference model that incorporates the common features from the joint datasets and methods for the shear-wave velocity structure of the Chinese mainland lithosphere.

The influence of task type and movement speed on lower limb kinematics during single-leg tasks

BackgroundSingle-leg squats and step-downs are commonly used to assess kinematic variables that may be linked to injuries. Task type and movement speed may influence the outcomes of interest because of different balance requirements. Research questionWhat is the influence of task type and movement speed on lower limb kinematics? MethodsThis is a cross-sectional within-subjects study where 22 physically active females performed three single-leg functional tasks (Squat, Anterior step-down, and Lateral step-down) at three movement speeds (slow [5 s], fast [2 s], and self-selected), while three-dimensional kinematic variables were recorded. Displacement values from the initial position in single-leg support until 60° or peak knee flexion were calculated. Two-way repeated measures ANOVA was used to compare tasks and speeds, and Cohen’s d effect size (ES) was calculated for significant pairwise comparisons. ResultsAt 60°, lateral step-down presented the greatest hip adduction (large ES) and internal rotation (small ES). The anterior step-down had the lowest knee abduction displacement while the squat had the greatest (small to medium ES). At peak knee flexion, values increased but differences between tasks followed a similar pattern. Slow speed induced smaller displacement angles at the knee and hip (trivial to small ES). SignificanceWhen knee abduction is the variable of interest, the SLS may be the best test since it elicits the greatest displacement, but when evaluating hip motion, SDLAT might be best. Knee abduction and internal rotation were lowest in the slow condition, suggesting that faster speed may be more appropriate to detect abnormal movement patterns. However, the small difference in absolute values (i.e., degrees of movement) may indicate that the differences are not clinically significant, particularly for speed comparisons. Researchers and clinicians should take this into consideration when choosing the most appropriate task and the instruction to give during its execution.

Subjective visual vertical deviation in patients with early-onset direction-changing horizontal positional nystagmus

ObjectiveOtolithic dysfunction is investigated in cases of direction-changing horizontal positional nystagmus (DCHPN) due to peripheral vestibular disorders. MethodsThe static-subjective visual vertical (S-SVV) was conducted in DCHPN cases within 48 h after onset. ResultsThe absolute values of S-SVV deviations of patients with Light cupula and lateral canal-benign paroxysmal positional vertigo-cupulolithiasis (L-BPPV-Cup) were significantly different from those of healthy subjects (p < 0.001, p < 0.05, respectively), whereas there were no significant differences in those of patients with L-BPPV-Canalolithiasis-geotropic (L-BPPV-Can-g) or L-BPPV-Can-ageotropic (L-BPPV-Can-a) versus healthy subjects. Significant differences were found in S-SVV (+: deviation to the affected side, −: deviation to the unaffected side) between patients with Light cupula and those with L-BPPV-Can-g, L-BPPV-Can-a and L-BPPV-Cup (p < 0.01, p < 0.05, and p < 0.001, respectively), as well as between those with L-BPPV-Can-g and L-BPPV-Cup (p < 0.01). The S-SVV in patients with Light cupula, L-BPPV-Can-g, and L-BPPV-Can-a deviated more to the affected side, whereas that in patients with L-BPPV-Cup deviated more to the unaffected side. ConclusionMild otolithic dysfunctions were found in patients with DCHPN due to the presence of peripheral vestibular disorders within 48 h after onset. The extent of otolithic (utricular) disorders in patients with DCHPN is estimated in decreasing order as follows: Light cupula > L-BPPV-Cup > L-BPPV-Can-g and L-BPPV-Can-a. Many patients with L-BPPV-Cup likely suffer from disorders of the pars externa of the utricular macula, whereas many patients with L-BPPV-Can-g likely suffer from disorders of the pars interna of the utricular macula. L-BPPV-Can-a and L-BPPV-Can-g must be induced by a common mild utricular disorder.

Evaluation of biomechanics using different traction devices in distalization of maxillary molar with clear aligners: a finite element study

The study aimed to mechanically evaluate the tooth displacement of molar distalization by clear aligners combined with micro-implant through different traction devices using finite element analysis. A three-dimensional finite element model of complete maxillary dentition was constructed. Simultaneously move the maxillary first and second molars 0.2 mm distally at the height of 4 mm and 6 mm of micro-implant, and 150 g force was applied to button, precision cut and angelbutton respectively. Initial tooth movement in six different conditions of anterior tooth and molars was analyzed and calculated with ANSYS software. All the upper anterior tooth exhibited uncontrolled labial tipping and intrusion upon the six conditions, and the central incisor showed the largest tendency of crown labial inclination. Among the absolute values of crown-root displacement difference of the anterior tooth in sagittal direction, the angelbutton was the smallest, which means the torque control ability was superior to others. However, button played a more accurate role in the sagittal and vertical control of canine. With the increase of micro-implant height, the torque control ability of anterior tooth was decreased, but the intrusion trend increased. The controlled distal inclination with extrusion of the first molar and uncontrolled distal inclination with intrusion of the second molar were observed, and the angelbutton had more effective horizontal and vertical control on molars, which was close to bodily movement than others. As a new type of traction device, angelbutton has excellent anchorage control effect in clear aligners therapy of molar distalization, which further realizes the accurate expression of orthodontic force.

Complex function solution for deformation and failure mechanism of inclined coal seam roadway

The stressed environment of the inclined coal seam roadway is complex and changeable, and the damage degree of surrounding rock increases, threatening the safe mining of coal mines. In order to take targeted support measures to control the stability of roadway surrounding rock, it is very important to study the stress and deformation characteristics of roadway surrounding rock in inclined coal seam. Therefore, this paper analyzes the deformation and failure law of inclined coal seam roadway according to the theory of complex variable function. It optimizes the solution process and accuracy of the mapping function coefficient and deduces the analytical solution of surrounding rock stress and deformation inclined coal seam roadway. The deformation and failure mechanism of surrounding rock in inclined coal seam roadway is revealed theoretically, and further use numerical simulation and physical simulation tests for supplementary analysis and verification. The results show that the stress and deformation of roadway surrounding rock in inclined coal seam show obvious asymmetric distribution characteristics. The stress and deformation of roadway surrounding rock on the right side are greater than on the left side. The two sides of the roadway, the right side of the roof and the roof angle of the right side, are the key positions of roadway stress concentration and deformation. According to the variation law of stress and deformation distribution of roadway surrounding rock, roadway cyclic deformation and failure theory is put forward. The numerical simulation and physical simulation tests show that the deformation and failure law of roadway is consistent with the theoretical analysis results, and there are differences in numerical values. The cyclic deformation and failure mechanism of roadway in inclined coal seam is verified, which can provide theoretical guidance for roadway support design.

Peran Literasi EkonomiDalam Memoderasi Pengaruh Iklan dan Konformitas terhadap Perilaku Konsumtif

This study aims to analyze the effect of advertising and conformity on consumptive behavior with economic literacy as a moderating variable. The population in this study were all active students of the 2017 Semarang State University Accounting Economics Education Study Program, totaling 92 students, all of whom were used as research respondents. Methods of data collection using a questionnaire. The data analysis method used is descriptive statistical analysis and Moderated Regression Analysis (MRA) with absolute difference value test. The results showed that advertising had a positive and significant effect on consumptive behavior by 19.01%. Conformity has a positive and significant effect on consumptive behavior by 25.20%. Economic literacy is not able to moderate the effect of advertising and conformity on consumptive behavior.

Mm-Wave Radar-Based Vital Signs Monitoring and Arrhythmia Detection Using Machine Learning.

A non-contact, non-invasive monitoring system to measure and estimate the heart and breathing rate of humans using a frequency-modulated continuous wave (FMCW) mm-wave radar at 77 GHz is presented. A novel diagnostic system is proposed which extracts heartbeat phase signals from the FMCW radar (reconstructed using Fourier series analysis) to test a three-layer artificial neural network model to predict the presence of arrhythmia in individuals. The effect of person orientation, distance of measurement and movement was analyzed with respect to a reference device based on statistical measures that include number of outliers, mean, mean squared error (MSE), mean absolute error (MAE), median absolute error (medAE), skewness, standard deviation (SD) and R-squared values. The individual oriented in front of the radar outperformed almost all other orientations for most distances with an expected d = 90 cm and d = 120 cm. Furthermore, it was found that the heart rate that was measured while walking and the breathing rate which was measured for a motionless individual generated results with the lowest SD and MSE. An artificial neural network (ANN) was trained using the MIT-BIH database with a training accuracy of 93.9 % and an R2 value = 0.876. The diagnostic tool was tested on 15 subjects and achieved a mean test accuracy of 75%.

Fluid-responsiveness, blood volume and perfusion in preoperative haemodynamic optimisation of hip fracture patients; a prospective observational study.

Preoperative resuscitation strategies in patients with hip fracture (HF) are lacking. We aimed to investigate fluid-responsiveness, peripheral perfusion index (PPI) and blood volume (BV)-status in patients with HF undergoing resuscitation in the preoperative phase. In a prospective observational study, we evaluated preoperative fluid-responsiveness, indices of perfusion and BV before and after lumbar epidural analgesia in 50 patients with HF shortly after admittance. Initially, 18 (36%) patients were fluid-responsive (≥10% increased SV in response to 250 ml fluid bolus) and 13 (26%) presented hypovolaemia (deviation of measured BV from estimated BV ≤ 0.9). According to fluid-responsiveness, no difference in absolute values of cardiac index (CI) (2.7L [2.1-3.3] vs. 2.8 L [2.3-3.4], p= .5) was seen, but cardiac output (CO) rose significantly in the hypovolaemic patients: 9% [5-18] vs. 1% [-3-7], p= .004. After epidural analgesia, 26 (52%) patients were again fluid-responsive and 15 (30%) were hypovolaemic. CI was now significantly lower in fluid-responsive patients (2.2L [1.7-2.7] vs. 2.9 L [2.3-3.5], p= .001). Prior to epidural analgesia, no significant trend towards hypovolaemic patients having lower indices of perfusion was seen. After epidural analgesia, more patients with hypovolaemia presented with PPI≤1.5 (8 (53%) vs. 3 (9%), p= .001) and absolute values of PPI were also significantly lower if IBV was low (1.4 [0.9-3.2] vs. 3.2 [2.4-4.8], p= .01). PPI correlated with hypovolaemia after epidural analgesia (rho 0.4 [0.1-0.7], p= .007). Preoperative fluid-responsivity in HF patients might be attributable to elements of hypovolaemia and sympathetic compensatory ability conjointly, confounding the use of SV-guided resuscitation. PPI could be associated with BV, which may support clinicians during perioperative haemodynamic optimisation.

A novel damage detection method in beam-like structures based on the relation between modal kinetic energy and modal strain energy and using only damaged structure data

Dynamic damage detection methods, in which changes in the dynamic properties of structures such as frequencies and mode shapes are used to identify the location of damage, are generally based on the comparison between damaged and undamaged states of structures. In this study, a damage detection method in beam-like structures is introduced in which the location of damage is determined using only dynamic data of damaged structure. In this method, in the constituent elements of a beam, the absolute difference value between a coefficient of the modal strain energy of one element and a coefficient of the modal kinetic energy of the same element or another element of that beam is introduced as an indicator of the damage location. These coefficients depend only on displacement, rotation, and the element length of damaged structure; they are independent of data such as mechanical properties and geometrical characteristics of the cross section. Thus, this method does not require any mechanical and geometric data from the damaged structure or the base model; it only needs modal displacements and the length of damaged beam elements. Satisfactory capability of the proposed method in detecting damage is presented using finite element model of damaged beams with diverse geometries and boundary conditions. The results of dynamic tests performed on an existing damaged reinforced concrete bridge and the experimental model of a damaged steel cantilever beam are also used to validate the proposed method.

Performance evaluation and equivalent conversion of waterborne epoxy resin emulsified asphalt based on different evaporation methods

To accurately and effectively evaluate the performance of waterborne epoxy resin emulsified asphalt (WEREA), two emulsifiers and two waterborne epoxy resin (WER) systems were selected to prepare WEREA, and three evaporation methods of direct heating, room temperature (25 °C), and medium temperature (80 °C) were designed to obtain the evaporation residue of WEREA. The results demonstrate that the direct heating evaporation method is not suitable for obtaining the evaporation residue of WEREA, while the room-temperature and medium-temperature evaporation methods are feasible. Under the room-temperature and medium-temperature evaporation methods, the performances of WEREA show a consistent variation with the change of relevant variables. However, there are also some differences in numerical values. Considering the high and low-temperature performance and mechanical performance of WEREA, the cationic WEREA containing 20% type Ⅰ WER system or 30% type II WER system is recommended. Moreover, an equivalent conversion relationship of performance of WEREA under these two evaporation methods was established through linear regression analysis. Therefore, the performance of WEREA can be evaluated based on the medium-temperature evaporation method, which is simple and effective. And then, its performance after curing under room-temperature conditions can be obtained through equivalent conversion. This study is of great significance for the accurate and efficient performance evaluation of WEREA and its large-scale application.

Volatility forecasting using intraday information with the CARR models for the China stock markets

ABSTRACT This study mainly focuses on utilizing the range-based CARR and CARRX models to explore the non-trading effects during the lunch break and overnight periods in volatility changes forecasting for the two stock markets in China. We find that the price difference in absolute values between the close price in day t-1 and the open price in day t are able to predict the volatility change in the morning trading session significantly. The price range during the lunch break and the trading volume change percentage in the morning session appear positive correlation with the volatility in the afternoon trading session.

Dew point pressure of gas condensates, modeling and a comprehensive review on literature data

The accurate and in-time prediction of gas condensates dew point pressure (PDew) is of great importance regarding the technical and economic points of view for fluid characterization, reservoir performance calculations, planning the development of gas condensate reservoirs, and design and optimization of production systems. Although the laboratory tests provide the most accurate and reliable results, it is an expensive and time-consuming process sometimes associated with some errors. Artificial intelligence-based methods have emerged as promising tools in different aspects of engineering. In this study, after a thorough analysis of the gas condensate data samples, the application of different intelligent modeling is investigated. A databank of 721 data samples is gathered, and different intelligent methods approaches are used for modeling. The results of three different data mining methods are combined using Committee Machine Intelligent Systems (CMIS) in an attempt to receive more accurate results. Three different methods of arithmetic, geometric, and harmonic approaches are utilized to develop the CMIS model. It was concluded that the harmonic CMIS yields the best predictions by average absolute relative deviation (AARD) and R2 values of 3.456% and 0.9702, respectively. This novel CMIS model could successfully outperform all the developed initial models. Additionally, a literature review showed that the proposed model could outperform the previously published models including artificial intelligence, equation of state, and correlation-based method considering both prediction accuracy and data coverage.