To see the other types of publications on this topic, follow the link: GSS coefficient.
Journal articles on the topic 'GSS coefficient'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'GSS coefficient.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
N., Shaheem, and A. V. Venugopalan. "Comparison between different radiological scoring systems in predicting post-PCNL outcome." International Surgery Journal 10, no. 10 (2023): 1606–15. http://dx.doi.org/10.18203/2349-2902.isj20232982.
Full textAbstract:
Background: Various scoring systems, including Guy's stone score (GSS), S.T.O.N.E. score, and Clinical Research Office of the Endourological Society (CROES) nomogram, have been assessed for predicting post-percutaneous nephrolithotomy (PCNL) success in terms of stone-free status (SFS) and complications. Our study aims to determine the optimal predictor of SFS among these systems and assess their efficacy in predicting perioperative factors and complications, using modified Clavien grade. Methods: This prospective hospital-based cohort study involved 107 patients aged ≥18 years who underwent standard PCNL (tract size >24 Fr) within a year. GSS, S.T.O.N.E. score, and CROES nomogram were calculated using preoperative computed tomography (CT) scans. Comparisons between 'stone-free' and 'residual-stone' groups were statistically analyzed. Results: All parameters effectively predicted SFS. S.T.O.N.E. score exhibited excellent discriminatory power (AUC 0.844; 95% CI: 0.762-0.907), followed by GSS (AUC 0.756; 95% CI: 0.663-0.834) and CROES nomogram (AUC 0.749; 95% CI: 0.656-0.828). S.T.O.N.E. score, with an AUC of 0.844, proved the most accurate predictor at ≤7 cut-off. GUY's score correlated positively with operative time and hospital stay (correlation coefficient 0.403, 0.34). S.T.O.N.E. score also positively correlated with these factors (correlation coefficient 0.443, 0.37). CROES nomogram negatively correlated with operative time and hospital stay (correlation coefficient -0.374, -0.314). Conclusions: All scoring systems effectively predict post-PCNL SFS, with S.T.O.N.E. score being the most predictive. GSS and S.T.O.N.E. score associate significantly with operative time and hospital stay. Both GSS and S.T.O.N.E. score show significant associations with perioperative complications assessed by modified Clavien grade.
2
Mo, Guowei, Yunxian Cui, Junwei Yin, and Pengfei Gao. "Influence of ZnO Film Deposition Parameters on Piezoelectric Properties and Film-to-Substrate Adhesion on a GH4169 Superalloy Steel Substrate." Micromachines 13, no. 4 (2022): 639. http://dx.doi.org/10.3390/mi13040639.
Full textAbstract:
ZnO film is widely used in the field of health monitoring sensors, which has high requirements for the piezoelectric coefficient and film-to-substrate adhesion of the ZnO film. In this study, ZnO thin films were grown on a GH4169 superalloy steel (GSS) substrate using magnetron sputtering, and the effects of the sputtering power, argon–oxygen ratio, and sputtering pressure on the piezoelectric coefficient and film-to-substrate adhesion were studied. The composition, microstructure, and crystal orientation of ZnO thin films deposited under different process parameters were analyzed using X-ray diffraction (XRD), a scanning electron microscope (SEM), and an energy spectrum analyzer (EDS). The piezoelectric coefficient d33 was measured using a piezoelectric coefficient measuring instrument. The critical value of adhesion between the film and substrate was measured using the scratch method. The results demonstrated that the ZnO films had the most desirable properties when the sputtering power was 150 W, the argon–oxygen ratio was 25:10, and the sputtering pressure was 0.7 Pa. The XRD results showed that the ZnO film samples had the strongest (002) crystal orientation at 2θ = 34.4°; the SEM photos showed that the film samples were flat and uniform; and the EDS composition analysis results showed that the composition was close to the theoretical value. The maximum d33 coefficient value was 5.12 pC/N, and the maximum value of film-to-substrate adhesion between the ZnO films and GSS substrate was 4220 mN.
3
Reinig, Bruce A., and Roberto J. Mejias. "On the Measurement of Participation Equality." International Journal of e-Collaboration 10, no. 4 (2014): 32–48. http://dx.doi.org/10.4018/ijec.2014100103.
Full textAbstract:
Participation equality is often a key process construct in research models that examine the effects of group support systems (GSS) technology and e-collaboration. GSS are generally thought to reduce the dispersion of participation among team members and thus make participation more equally distributed. However, research conclusions in the literature regarding participation equality are not always consistent with this finding. Researchers have used a variety of approaches to operationalize participation equality including unit-based measures, such as the standard deviation, and dimensionless measures such as the Gini coefficient and the coefficient of variation. Researchers have also varied in their measurement of participation units with some counting phenomena such as comments, words, or remarks. The authors report on an exploratory study that demonstrates conditions in which research conclusions regarding the participation equality construct are dependent on both the participation unit analyzed and whether a unit-based or dimensionless measure is used to compute participation equality. The authors conclude with recommendations for researchers investigating participation equality and practitioners that seek to measure and track participation equality in their collaborative work practices.
4
CHATTERJEE, PRASANTA, DEB KUMAR GHOSH, UDAY NARAYAN GHOSH, and BISWAJIT SAHU. "Non-planar dust-acoustic solitary waves and double layers in a four-component dusty plasma with super thermal electrons." Journal of Plasma Physics 79, no. 5 (2013): 691–98. http://dx.doi.org/10.1017/s0022377813000287.
Full textAbstract:
AbstractThe properties of non-planar (cylindrical and spherical) dust-acoustic solitary waves (DA SWs) and double layers (DLs) in an unmagnetised collisionless four-component dusty plasma, whose constituents are positively and negatively charged dust grains, super thermal electrons and Boltzmannian ions are investigated by deriving the modified Gardner (MG) equation. The well known reductive perturbation method is employed to derive the MG equation and solve it numerically to study the nonlinear features of the finite amplitude non-planar DA Gardner solitons (GSs) and DLs, which are shown to exist for κ around its critical value κc (where, κ is the super thermal parameter and κc is the value of κ corresponding to the vanishing of the nonlinear coefficient of the Korteweg-de Vries (K-dV) equation). It is seen that the properties of non-planar DA SWs and DLs are significantly differs in non-planar geometry from planar geometry. It is also found that the magnitude of the amplitude of positive and negative GSs decreases with κ and the width of positive and negative GSs increases with the increase of κ.
5
Hanisch, F., and J. N. Crowley. "Ozone decomposition on Saharan dust: an experimental investigation." Atmospheric Chemistry and Physics Discussions 2, no. 6 (2002): 1809–45. http://dx.doi.org/10.5194/acpd-2-1809-2002.
Full textAbstract:
Abstract. The heterogeneous reaction between O3 and authentic Saharan dust surfaces was investigated in a Knudsen reactor at approx 296 K. O3 was destroyed on the dust surface and O2 was formed with conversion efficiencies of 1.0 and 1.3 molecules O2 per O3 molecule destroyed for unheated and heated samples, respectively. No O3 desorbed from exposed dust samples, showing that the uptake was irreversible. The uptake coefficients for the irreversible destruction of O3 on (unheated) Saharan dust surfaces depended on the O3 concentration and varied between 3.5 x10-4 and 5.5 x10-6 for the initial uptake coefficient (g0 approx 3 x10-5 at 30 ppbv O3 STP) and between 4.8 x10-5 and 2.2 x10-6 for the steady-state uptake coefficient (gss approx 7 x10-6 at 30 ppbv O3 STP). At very high O3 concentrations the surface was deactivated, and O3 uptake ceased after a certain exposure period. Sample re-activation (i.e. de-passivation) was found to occur over periods of hours, after exposure to O3 had ceased, suggesting that re-activation processes play a role both in the laboratory and in the atmosphere.
6
Hanisch, F., and J. N. Crowley. "Ozone decomposition on Saharan dust: an experimental investigation." Atmospheric Chemistry and Physics 3, no. 1 (2003): 119–30. http://dx.doi.org/10.5194/acp-3-119-2003.
Full textAbstract:
Abstract. The heterogeneous reaction between O3 and authentic Saharan dust surfaces was investigated in a Knudsen reactor at approx 296 K. O3 was destroyed on the dust surface and O2 was formed with conversion efficiencies of 1.0 and 1.3 molecules O2 per O3 molecule destroyed for unheated and heated samples, respectively. No O3 desorbed from exposed dust samples, showing that the uptake was irreversible. The uptake coefficients for the irreversible destruction of O3 on (unheated) Saharan dust surfaces depended on the O3 concentration and varied between 3.5 x 10-4 and 5.5 x 10-6 for the initial uptake coefficient (g0 approx 3 x 10-5 at 30 ppbv O3 STP) and between 4.8 x 10-5 and 2.2 x 10-6 for the steady-state uptake coefficient (gss approx 7 x10-6 at 30 ppbv O3 STP). At very high O3 concentrations the surface was deactivated, and O3 uptake ceased after a certain exposure period. Sample re-activation (i.e. de-passivation) was found to occur over periods of hours, after exposure to O3 had ceased, suggesting that re-activation processes play a role both in the laboratory and in the atmosphere.
7
UCHYIGIT, GULDEN, and KEITH CLARK. "A NEW FEATURE SELECTION METHOD FOR TEXT CLASSIFICATION." International Journal of Pattern Recognition and Artificial Intelligence 21, no. 02 (2007): 423–38. http://dx.doi.org/10.1142/s0218001407005466.
Full textAbstract:
Text classification is the problem of classifying a set of documents into a pre-defined set of classes. A major problem with text classification problems is the high dimensionality of the feature space. Only a small subset of these words are feature words which can be used in determining a document's class, while the rest adds noise and can make the results unreliable and significantly increase computational time. A common approach in dealing with this problem is feature selection where the number of words in the feature space are significantly reduced. In this paper we present the experiments of a comparative study of feature selection methods used for text classification. Ten feature selection methods were evaluated in this study including the new feature selection method, called the GU metric. The other feature selection methods evaluated in this study are: Chi-Squared (χ2) statistic, NGL coefficient, GSS coefficient, Mutual Information, Information Gain, Odds Ratio, Term Frequency, Fisher Criterion, BSS/WSS coefficient. The experimental evaluations show that the GU metric obtained the best F1 and F2 scores. The experiments were performed on the 20 Newsgroups data sets with the Naive Bayesian Probabilistic Classifier.
8
Eroglu, Emre. "Discussing Total Electron Content over the Solar Wind Parameters." Mathematical Problems in Engineering 2022 (February 28, 2022): 1–14. http://dx.doi.org/10.1155/2022/9592008.
Full textAbstract:
Modeling and forecasting of Total Electron Content (TEC) values by an Artificial Neural Network model (ANNm) have high agreement on November 2003, 2004 superstorms. The work discusses Solar Wind Parameters (SWp) from OMNI (Operating Missions as a Node on the Internet) and TEC (TECU) data (International Reference Ionosphere) IRI-2012, IRI-2016 on November 20, 2003 (Dst = –422 nT) and on November 08, 2004 (Dst = –374 nT) Geomagnetic Storms (GSs). The paper commences with a 120-hour GS exhibition of SWp and proceeds with the correlation data of the variables, their hierarchical tracks, and inner dispersions. The ANNm with SWp as the input and TEC data as the output are introduced. The performance of the ANNm for 2003 and 2004 superstorms is adequate. The Correlation Coefficient (R) and Root Mean Square Error (RMSE) of the ANNm are 97.5%, 1.17 TECU (IRI-2012), and 97.9%, 1.09 TECU (IRI-2016) for the 2003 GS and 97.0%, 0.89 TECU (IRI-2012), and 98.0%, 1.61 TECU (IRI-2016) for 2004 GS. Parameters effect of the R constant of TEC data points out to the dynamic pressure (nPa), the magnetic field Bz component (nT), the flow speed (km/s), and the proton density (1/cm3). Besides, the absolute total error and the variance of the predicted TEC data for November 2003 and November 2004 GSs are 0.06 (0.30%) with 0.013 variance (IRI-2012), 0.09 (0.49%) with 0.016 variance (IRI-2016) for 2003 storm and 0.13 (0.73%) with 0.033 variance (IRI-2012), and 0.11 (1.06%) with 0.035 variance (IRI-2016) for 2004. It means that the paper models TEC data with considerable consistency over the SWp.
9
Rossi, Gemma Caterina Maria, Federica Bettio, Mariano González-Pérez, Aba Briola, Gemma Ludovica Maria Pasinetti, and Luigia Scudeller. "The 17-Item Computer Vision Symptom Scale Questionnaire (CVSS17): Translation, Validation and Reliability of the Italian Version." International Journal of Environmental Research and Public Health 19, no. 5 (2022): 2517. http://dx.doi.org/10.3390/ijerph19052517.
Full textAbstract:
Background. To validate the 17-item Computer Vision Symptom Scale questionnaire (CVSS17) in Italian. Methods. Cross-sectional validation study on video terminal (VDT) users and a reference sample of subjects not working at a VDT (control group), cognitively able to respond to a health status interview. The Italian self-administered version of the CVSS17 questionnaire was administered to all participants. The reliability and validity of the Italian translation of the CVSS17 were tested using standard statistical methods for questionnaire validation. The Rasch analysis was performed as well. Results. A total of 216 subjects were enrolled. Concerning the reliability, the Cronbach’s alpha coefficient was 0.925 (from 0.917 to 0.924), and the test–retest stability was 0.91 (<0.001). Concerning the validity, the control group had significantly better scores, and there were good correlations between responses to the CVSS17 and analogous domains of the GSS. Conclusion. The Italian version of the CVSS17 has shown psychometric properties comparable to those of the Spanish version, having good validity, discriminatory power, internal consistency and reliability. The questionnaire is a specific measure of vision-related quality of life in Italian-speaking VDT workers and can be used both in clinical practice and for research purposes.
10
Panggoa, Risliana. "The Suitability of Building Permit Proposal and Implementation in Kecamatan Makale Kabupaten Tana Toraja." JURNAL PEMBANGUNAN WILAYAH & KOTA 8, no. 1 (2012): 87. http://dx.doi.org/10.14710/pwk.v8i1.11561.
Full textAbstract:
The development of a city is always influenced by the activities of the community which requiredland for the activities to take place. Limited land availability demanded a sound control mechanismto ensure the sustainability of the economic growth. The general society has not yet fullyunderstood Building Permit (Izin Mendirikan Bangunan ‐ IMB) as the instrument of control ofspatial use, resulting in mismatches between the actual building and the one proposed in the IMB.This research aimed to find the factors driving the mismatches in the IMB implementation withinthe local Makale community’s understanding to concept of IMB. The study employed quantitativedescriptive methods using frequency distribution tables and factor analysis. Factor analysis showedhow lack of understanding and awareness in the concept of IMB, together with poor policy andexecution by the local government have prevented the fully implementation. Some of theviolations found included total building area, building function, Basic Structural Coefficient(Koefisien Dasar Bangunan ‐ KDB), Building Line (Garis Sempadan Bangunan ‐ GSB), and River Line(Garis Sempadan Sungai ‐ GSS). The study concluded the need for IMB awareness promotionthrough socialization along with the technical procedures, enhancement of IMB monitoring andevaluation processes, finalization of IMB as regional regulation, and enforcement.Keywords: city development, land use control, IMB, law enforcement
11
Bekir Erhan, Orhan, Karaçam Aydin, and Astuti Yuni. "The Examination of Game Skills of Children Aged 5-6 Years Participating in Movement Education." IgMin Research 2, no. 6 (2024): 419–24. http://dx.doi.org/10.61927/igmin196.
Full textAbstract:
This study examines the game skills of children aged 5-6 years participating in movement education programs. Given the crucial role of physical and cognitive skill development in early childhood, the study aims to explore how structured physical activities influence children’s motor skills, cognitive abilities, and social interactions. A descriptive survey model was employed involving 144 parents of children participating in movement education. The Game Skills Scale (GSS) was utilized to measure children’s game skills, and data were analyzed using SPSS 25, with t-tests for pairwise comparisons and Pearson’s correlation coefficient applied to determine relationships between variables, with a significance level set at p < 0.05. The results indicate that the game skills of children participating in movement education are notably high, with no significant differences based on gender or age. Furthermore, the duration of participation in movement education did not significantly impact the children’s game skills. These findings underscore the importance of incorporating structured physical activity programs in early childhood education to promote comprehensive development. The study contributes to the existing literature by highlighting the multifaceted benefits of movement education and providing insights for optimizing early childhood physical activity interventions.
12
Wang, Yingjie, Fangju Liu, Xin Zhou, et al. "Alleviation of Oral Exposure to Aflatoxin B1-Induced Renal Dysfunction, Oxidative Stress, and Cell Apoptosis in Mice Kidney by Curcumin." Antioxidants 11, no. 6 (2022): 1082. http://dx.doi.org/10.3390/antiox11061082.
Full textAbstract:
Aflatoxin B1 is a contaminant widely found in food and livestock feed, posing a major threat to human and animal health. Recently, much attention from the pharmaceutical and food industries has been focused on curcumin due to its strong antioxidant capacity. However, the therapeutic impacts and potential mechanisms of curcumin on kidney damage caused by AFB1 are still incomplete. In this study, AFB1 triggered renal injury in mice, as reflected by pathological changes and renal dysfunction. AFB1 induced renal oxidative stress and interfered with the Keap1–Nrf2 pathway and its downstream genes (CAT, SOD1, NQO1, GSS, GCLC, and GCLM), as manifested by elevated oxidative stress metabolites and reduced antioxidant enzymes activities. Additionally, AFB1 was found to increase apoptotic cells percentage in the kidney via the TUNEL assay, along with increased expression of Cyt-c, Bax, cleaved-Caspase-3, Caspase-9, and decreased expression of Bcl-2 at the transcriptional and protein levels; in contrast, for mice given curcumin, there was a significant reversal in kidney coefficient, biochemical parameters, pathological changes, and the expression of genes and proteins involved in oxidative stress and apoptosis. These results indicate that curcumin could antagonize oxidative stress and apoptosis to attenuate AFB1-induced kidney damage.
13
Triveni, S., and N. Maheshbabu. "THE SELF-EFFICACY AND PERCEIVED SOCIAL SUPPORT AMONG HIV-POSITIVE ADOLESCENTS: A CORRELATIONAL STUDY." International Journal of Current Research and Modern Education (IJCRME) 7, no. 2 (2022): 1–9. https://doi.org/10.5281/zenodo.6804946.
Full textAbstract:
Human immunodeficiency virus weakens a person’s immune system by destroying the important cells that fight disease and infection. Untreated HIV affects and kills CD4 cells, which are a type of immune cell called T cell. Over a period of time, as HIV kills more CD4 cells, body is more likely to get various types of conditions and cancers.The purpose of this study was to assess the significant differences and relationship between General Self-efficacy and Perceived Social Support among HIV-Positive Adolescents across gender.The data was collected from HIV-Positive adolescents using purposive sampling method. A sample of 84 Adolescents (39 males & 45 females) aged from 13 to 24 years were selected from 3 HIV home-care Centres with Permission. The data was collected using the instruments such as General Self-Efficacy Scale (GSS) and Multidimensional Scale of Perceived Social Support (MSPSS). Further, the collected data was analysed using Mann-Whitney U-test and Spearman’s coefficient correlation test. The findings of the study revealed that there is no significant difference in General Self-Efficacy andthere is no significant difference in Perceived Social Support among male & female HIV Positive adolescents. It was also observed that there is a significant positive relationship between General Self-efficacy and Perceived Social Support among HIV positive adolescents.
14
Triveni, S., and N. Maheshbabu. "THE SELF-EFFICACY AND PERCEIVED SOCIAL SUPPORT AMONG HIV-POSITIVE ADOLESCENTS: A CORRELATIONAL STUDY." International Journal of Current Research and Modern Education (IJCRME) 7, no. 2 (2022): 1–9. https://doi.org/10.5281/zenodo.6820778.
Full textAbstract:
Human immunodeficiency virus weakens a person’s immune system by destroying the important cells that fight disease and infection. Untreated HIV affects and kills CD4 cells, which are a type of immune cell called T cell. Over a period of time, as HIV kills more CD4 cells, body is more likely to get various types of conditions and cancers.The purpose of this study was to assess the significant differences and relationship between General Self-efficacy and Perceived Social Support among HIV-Positive Adolescents across gender.The data was collected from HIV-Positive adolescents using purposive sampling method. A sample of 84 Adolescents (39 males & 45 females) aged from 13 to 24 years were selected from 3 HIV home-care Centres with Permission. The data was collected using the instruments such as General Self-Efficacy Scale (GSS) and Multidimensional Scale of Perceived Social Support (MSPSS). Further, the collected data was analysed using Mann-Whitney U-test and Spearman’s coefficient correlation test. The findings of the study revealed that there is no significant difference in General Self-Efficacy and there is no significant difference in Perceived Social Suppor tamong male & female HIV Positive adolescents. It was also observed that there is a significant positive relationship between General Self-efficacy and Perceived Social Support among HIV positive adolescents.
15
Nakagami, Koji. "Effects of sites and years on the coefficients of rising plate meter calibration under varying coefficient models." Grassland Science 62, no. 2 (2016): 128–32. http://dx.doi.org/10.1111/grs.12117.
Full text
16
Abredu, Pearl, Cai Li, and Frank Kofi Essien. "A Paradigm Shift in Unemployment Based on the Role of Business Ownership: Ghana as Case." Int'l Journal of Management Innovation Systems 7, no. 1 (2022): 16. http://dx.doi.org/10.5296/ijmis.v7i1.20033.
Full textAbstract:
Both researchers and policymakers have given the relationship between entrepreneurship and unemployment a lot of thought. The changes in the area of unemployment in the country has caused many people to move into owning their businesses. This activity has initiated a relief to the government since its responsibility is to create lucrative jobs to its citizens. This paper seeks to address the paradigm shift in unemployment in Ghana, the role of business ownership. The study explained the determinants of unemployment, and the entrepreneurship drive to unravel unemployment in the country. Using a cross-sectional dataset, the study focused on Ghana’s economic growth as well as the country’s unemployment rate. Using an online survey of 400 respondents and data from the Ghana Statistical Service (GSS) and the Global Entrepreneurship Monitor dataset as its key element in addressing the usefulness of the study. The researcher investigated a paradigm shift in unemployment using the SPSS tool (version 23.0) and regression for the data analysis. With a Cronbach Alpha of 0.898 which explains the reliability statistics of the study variables, the research result shows that at a coefficient of 0.73, Business ownership will have an aid to employment rate with a highly significant P-value of 0.000. Recommendation from the study is that Policymakers should investigate and assess the elements that influence entrepreneurship by placing reduction on the interest put on loan offered to young entrepreneurs.
17
Zhang, Mei Jie, Hou Zhi Wang, Hua Zhi Gu, and Ao Huang. "Analysis on Resistance Coefficients and Optimization of Structure and Properties of Porous Permeable Refractory." Key Engineering Materials 368-372 (February 2008): 1155–57. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.1155.
Full textAbstract:
The resistance coefficients through which gas flow permeable refractory are important properties and have great effect on the gas blowing parameters and gas-liquid two phase flowing characteristics in the metallurgy furnace such as ladles, tundish. In this paper, the resistance coefficients were measured according to the Forchheimer’s law. The results show when the gas flow rate is fixed, the viscosity resistance coefficient and inertia resistance coefficient decrease as the apparent porosity and average pore diameter increase. The viscous resistance coefficient is more lager than the inertial resistance coefficient. The resistance coefficients were analyzed by dimensional analysis and the statistical correlations between the resistance coefficients and parameters of porous permeable refractory were got based on the experimental data. In order to get high strength at low resistance coefficients, the raw materials particle degree were adjusted.
18
Chreng, Karodine, Han Soo Lee, and Soklin Tuy. "A Hybrid Model for Electricity Demand Forecast Using Improved Ensemble Empirical Mode Decomposition and Recurrent Neural Networks with ERA5 Climate Variables." Energies 15, no. 19 (2022): 7434. http://dx.doi.org/10.3390/en15197434.
Full textAbstract:
By conserving natural resources and reducing the consumption of fossil fuels, sustainable energy development plays a crucial role in energy planning. Specifically, demand-side planning must be researched and anticipated based on electricity consumption at the grounded level. Due to the global warming crisis, atmospheric conditions are among the most influential components that have altered electricity consumption patterns. In this study, 66 climate variables from the ERA5 reanalysis and the observed power demand at four grid substations (GSs) in Cambodia were examined using recurrent neural networks (RNNs). Using the cross-correlation function between power demand and each climate variable, statistically significant climate variables were sorted out. In addition, a wide range of feedback delays (FDs) was generated from the data on power demand and defined using 95% confidence intervals. The combination of the improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) technique with a nonlinear autoregressive neural network with exogenous inputs (NARX) and a nonlinear autoregressive neural network (NAR) produced a hybrid electricity forecasting model. The data were decomposed into the intrinsic mode functions (IMFs) and were then used as inputs in optimized NARX and NAR models. The performance of the various benchmarked models was analyzed and compared using mainly statistical indicators such as the normalized root mean square error (NMSE) and the coefficient of determination (R2). The hybrid models perform exceptionally well in predicting electricity demand, and the ICEEMDAN-NARX hybrid model with correlated climate variables performs the best among the tested experiments as a useful prediction tool.
19
Mo, Guowei, Yunxian Cui, Junwei Yin, and Pengfei Gao. "Development and Characterization of ZnO Piezoelectric Thin Film Sensors on GH4169 Superalloy Steel Substrate by Magnetron Sputtering." Micromachines 13, no. 3 (2022): 390. http://dx.doi.org/10.3390/mi13030390.
Full textAbstract:
At present, piezoelectric sensors are primarily applied in health monitoring areas. They may fall off owing to the adhesive’s durability, and even damage the monitored equipment. In this paper, a piezoelectric film sensor (PFS) based on a positive piezoelectric effect (PPE) is presented and a ZnO film is deposited on a GH4169 superalloy steel (GSS) substrate using magnetron sputtering. The microstructure and micrograph of ZnO piezoelectric thin films were analyzed by an X-ray diffractometer (XRD), energy dispersive spectrometer (EDS), scanning electron microscope (SEM), and atomic force microscope (AFM). The results showed that the surface morphology was dense and uniform and had a good c-axis-preferred orientation. According to the test results of five piezoelectric sensors, the average value of the longitudinal piezoelectric coefficient was 1.36 pC/N, and the average value of the static calibration sensitivity was 19.77 mV/N. We selected the sensor whose parameters are closest to the average value for the dynamic test experiment and we drew the output voltage response curve of the piezoelectric film sensor under different loads. The measurement error was 4.03% when repeating the experiment six times. The research achievements reveal the excellent performance of the piezoelectric film sensor directly deposited on a GH4169 superalloy steel substrate. This method can reduce measurement error caused by the adhesive and reduce the risk of falling off caused by the aging of the adhesive, which provides a basis for the research of smart bolts and guarantees a better application in structural health monitoring (SHM).
20
Manganaro, Roberta, Stella Marchetta, Raluca Dulgheru, et al. "Correlation between non-invasive myocardial work indices and main parameters of systolic and diastolic function: results from the EACVI NORRE study." European Heart Journal - Cardiovascular Imaging 21, no. 5 (2019): 533–41. http://dx.doi.org/10.1093/ehjci/jez203.
Full textAbstract:
Abstract Aims The present study sought to evaluate the correlation between indices of non-invasive myocardial work (MW) and left ventricle (LV) size, traditional and advanced parameters of LV systolic and diastolic function by 2D echocardiography (2DE). Methods and results A total of 226 (85 men, mean age: 45 ± 13 years) healthy subjects were enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study. Global work index (GWI), global constructive work (GCW), global work waste (GWW), and global work efficiency (GWE) were estimated from LV pressure-strain loops using custom software. Peak LV pressure was estimated non-invasively from brachial artery cuff pressure. LV size, parameters of systolic and diastolic function and ventricular-arterial coupling were measured by echocardiography. As advanced indices of myocardial performance, global longitudinal strain (GLS), global circumferential strain (GCS), and global radial strain (GRS) were obtained. On multivariable analysis, GWI was significantly correlated with GLS (standardized beta-coefficient = −0.23, P &lt; 0.001), ejection fraction (EF) (standardized beta-coefficient = 0.15, P = 0.02), systolic blood pressure (SBP) (standardized beta-coefficient = 0.56, P &lt; 0.001) and GRS (standardized beta-coefficient = 0.19, P = 0.004), while GCW was correlated with GLS (standardized beta-coefficient = −0.55, P &lt; 0.001), SBP (standardized beta-coefficient = 0.71, P &lt; 0.001), GRS (standardized beta-coefficient = 0.11, P = 0.02), and GCS (standardized beta-coefficient = −0.10, P = 0.01). GWE was directly correlated with EF and inversely correlated with Tei index (standardized beta-coefficient = 0.18, P = 0.009 and standardized beta-coefficient = −0.20, P = 0.004, respectively), the opposite occurred for GWW (standardized beta-coefficient =−−0.14, P = 0.03 and standardized beta-coefficient = 0.17, P = 0.01, respectively). Conclusion The non-invasive MW indices show a good correlation with traditional 2DE parameters of myocardial systolic function and myocardial strain.
21
Gao, Chenyang, Yahua He , and Yuelin Gao. "A Multi-Strategy Enhanced Hybrid Ant–Whale Algorithm and Its Applications in Machine Learning." Mathematics 12, no. 18 (2024): 2848. http://dx.doi.org/10.3390/math12182848.
Full textAbstract:
Based on the principles of biomimicry, evolutionary algorithms (EAs) have been widely applied across diverse domains to tackle practical challenges. However, the inherent limitations of these algorithms call for further refinement to strike a delicate balance between global exploration and local exploitation. Thus, this paper introduces a novel multi-strategy enhanced hybrid algorithm called MHWACO, which integrates a Whale Optimization Algorithm (WOA) and Ant Colony Optimization (ACO). Initially, MHWACO employs Gaussian perturbation optimization for individual initialization. Subsequently, individuals selectively undertake either localized exploration based on the refined WOA or global prospecting anchored in the Golden Sine Algorithm (Golden-SA), determined by transition probabilities. Inspired by the collaborative behavior of ant colonies, a Flight Ant (FA) strategy is proposed to guide unoptimized individuals toward potential global optimal solutions. Finally, the Gaussian scatter search (GSS) strategy is activated during low population activity, striking a balance between global exploration and local exploitation capabilities. Moreover, the efficacy of Support Vector Regression (SVR) and random forest (RF) as regression models heavily depends on parameter selection. In response, we have devised the MHWACO-SVM and MHWACO-RF models to refine the selection of parameters, applying them to various real-world problems such as stock prediction, housing estimation, disease forecasting, fire prediction, and air quality monitoring. Experimental comparisons against 9 newly proposed intelligent optimization algorithms and 9 enhanced algorithms across 34 benchmark test functions and the CEC2022 benchmark suite, highlight the notable superiority and efficacy of MSWOA in addressing global optimization problems. Finally, the proposed MHWACO-SVM and MHWACO-RF models outperform other regression models across key metrics such as the Mean Bias Error (MBE), Coefficient of Determination (R2), Mean Absolute Error (MAE), Explained Variance Score (EVS), and Median Absolute Error (MEAE).
22
Zechel, Christina, Mira Loy, Christiane Wegner, et al. "Molecular signature of stem-like glioma cells (SLGCs) from human glioblastoma and gliosarcoma." PLOS ONE 19, no. 2 (2024): e0291368. http://dx.doi.org/10.1371/journal.pone.0291368.
Full textAbstract:
Glioblastoma multiforme (GBM) and the GBM variant gliosarcoma (GS) are among the tumors with the highest morbidity and mortality, providing only palliation. Stem-like glioma cells (SLGCs) are involved in tumor initiation, progression, therapy resistance, and relapse. The identification of general features of SLGCs could contribute to the development of more efficient therapies. Commercially available protein arrays were used to determine the cell surface signature of eight SLGC lines from GBMs, one SLGC line obtained from a xenotransplanted GBM-derived SLGC line, and three SLGC lines from GSs. By means of non-negative matrix factorization expression metaprofiles were calculated. Using the cophenetic correlation coefficient (CCC) five metaprofiles (MPs) were identified, which are characterized by specific combinations of 7–12 factors. Furthermore, the expression of several factors, that are associated with GBM prognosis, GBM subtypes, SLGC differentiation stages, or neural identity was evaluated. The investigation encompassed 24 distinct SLGC lines, four of which were derived from xenotransplanted SLGCs, and included the SLGC lines characterized by the metaprofiles. It turned out that all SLGC lines expressed the epidermal growth factor EGFR and EGFR ligands, often in the presence of additional receptor tyrosine kinases. Moreover, all SLGC lines displayed a neural signature and the IDH1 wildtype, but differed in their p53 and PTEN status. Pearson Correlation analysis identified a positive association between the pluripotency factor Sox2 and the expression of FABP7, Musashi, CD133, GFAP, but not with MGMT or Hif1α. Spherical growth, however, was positively correlated with high levels of Hif1α, CDK4, PTEN, and PDGFRβ, whereas correlations with stemness factors or MGMT (MGMT expression and promoter methylation) were low or missing. Factors highly expressed by all SLGC lines, irrespective of their degree of stemness and growth behavior, are Cathepsin-D, CD99, EMMPRIN/CD147, Intβ1, the Galectins 3 and 3b, and N-Cadherin.
23
Sovilj, Milan. "Axial Dispersion in a Three-Phase Gas-Agitated Spray Extraction Column." Collection of Czechoslovak Chemical Communications 63, no. 2 (1998): 283–92. http://dx.doi.org/10.1135/cccc19980283.
Full textAbstract:
The continuous-phase axial dispersion coefficients of the three-phase gas-liquid-liquid system in a gas-agitated spray extraction column 10 cm i.d. at 20 °C were examined. The system used was water as continuous phase, toluene as dispersed phase, and air as gaseous phase. The rise in the gas phase superficial velocity increased the continuous-phase axial dispersion coefficient. A non-linear dependence between the continuous-phase axial dispersion coefficient and the continuous phase superficial velocity was observed. No correlation was found between the continuous-phase axial dispersion coefficient and dispersed phase superficial velocity. The increase in the gas phase hold-up corresponded to a slight increase in the continuous-phase axial dispersion coefficient. The increase in the dispersed phase hold-up generated a growth of the continuous-phase axial dispersion coefficient. A comparison was made of the continuous-phase axial dispersion coefficients of the three-phase (air-water-toluene) and two-phase (water-toluene) systems.
24
Li, Nie, Tian, Zhao, and Zhang. "The Impact of Equilibrium Gas Pressure and Coal Particle Size on Gas Dynamic Diffusion in Coal." Processes 7, no. 9 (2019): 571. http://dx.doi.org/10.3390/pr7090571.
Full textAbstract:
The diffusion coefficient of gases in coal varies with time. This study aims to develop an unsteady dynamic diffusion (UDD) model based on the decay of diffusion coefficient with time and the change of integral. This study conducted a series of gas desorption and diffusion experiments with three different combinations of particle sizes and gas pressures and compared the diffusion coefficients of the three models. The UDD model exhibited good fitting results, and both the UDD and bidisperse models fitted the experimental data better than the unipore model. In addition, the dynamic diffusion coefficient (DDe) decreased rapidly in the initial stage but gradually decreased to a stable level in the later stage. All the effective diffusion coefficients of the three models negatively correlated with the particle size. In the unipore model, the diffusion coefficient of coal samples with three particle sizes increased with gas pressure. In the bidisperse and UDD models, the diffusion coefficients (Dae, Die, and DDe) of 0.25–0.5 mm and 0.5–1.0 mm coal samples increased with gas pressure. However, DDe and Dae of 1.0–1.25 mm coal samples increased first and then decreased. Furthermore, Die decreased first and then increased, with no sign of significant pressure dependence. Finally, the correlation and significance between the constant and diffusion coefficient in the UDD model was investigated.
25
Limonova, A. S., A. I. Ershova, A. V. Kiseleva, et al. "Validation of genetic risk scores for hypertension in the Central Russian population." Cardiovascular Therapy and Prevention 22, no. 12 (2024): 3801. http://dx.doi.org/10.15829/1728-8800-2023-3801.
Full textAbstract:
Aim. To validate and evaluate the accuracy of 4 genetic risk scores (GRSs) for hypertension (HTN), previously created on European samples, on a population sample of the Ivanovo Oblast.Material and methods. For genetic analysis, targeted next-generation sequencing was used on a sample of the Central Russia (n=1682) based on the biobank collection. Four GRSs associated with HTN, previously developed for the European population, were selected for validation. The coefficient of determination and the area under the ROC curve were used as quality metrics for regression models. Additional validation was carried out to include all nucleotide sequence variants, regardless of linkage disequilibrium level. A combined GRS was compiled based on coefficients from individual GRSs using the clumping + thresholding (C+T) method.Results. The study demonstrated that the predictive value of previously developed GRSs when used for Central Russian population is lower than in the original studies. The proportion of explained variance was 0,5-0,8%. The best predictive ability (proportion of explained variance — 2,5%) was demonstrated using previously developed GRSs (Evangelou E, et al., 2018), which includes the largest number of nucleotide sequence variants (n=852).Conclusion. GRSs for HTN, developed on European samples, is not recommended for Russian population without preliminary validation. To create original GRSs, combining statistical parameters (β-coefficients and p-value) from different GRS is not recommended.
26
Sobieszuk, Paweł, Filip Ilnicki, and Ryszard Pohorecki. "Contribution of Liquid- and Gas-Side Mass Transfer Coefficients to Overall Mass Transfer Coefficient in Taylor Flow in a Microreactor." Chemical and Process Engineering 35, no. 1 (2014): 35–45. http://dx.doi.org/10.2478/cpe-2014-0003.
Full textAbstract:
Abstract Gas-liquid microreactors find an increasing range of applications both in production, and for chemical analysis. The most often employed flow regime in these microreactors is Taylor flow. The rate of absorption of gases in liquids depends on gas-side and liquid-side resistances. There are several publications about liquid-side mass transfer coefficients in Taylor flow, but the data about gas-side mass transfer coefficients are practically non existent. We analysed the problem of gas-side mass transfer resistance in Taylor flow and determined conditions, in which it may influence the overall mass transfer rate. Investigations were performed using numerical simulations. The influence of the gas diffusivity, gas viscosity, channel diameter, bubble length and gas bubble velocity has been determined. It was found that in some case the mass transfer resistances in both phases are comparable and the gas-side resistance may be significant. In such cases, neglecting the gas-side coefficient may lead to errors in the experimental data interpretation.
27
Sugimoto, Shogo, and Hiroshi Sugimoto. "Thermal transpiration flows induced by differences in accommodation coefficients." Physics of Fluids 34, no. 4 (2022): 042005. http://dx.doi.org/10.1063/5.0084455.
Full textAbstract:
The behavior of a rarefied gas between two parallel plates, each having its uniform temperature but having a square wave-like distribution of the accommodation coefficients, is numerically analyzed using the Direct Simulation Monte Carlo method. The gas temperature near the plate becomes close to the plate temperature only if the accommodation coefficient of the wall is large enough. A lower accommodation coefficient leads to the difference between the gas temperature and the adjacent wall. This temperature distribution induces a gas flow similar to the well-known thermal transpiration flow along the plate. When only one plate has a wave-like distribution of the accommodation coefficients, an array of vortical flow is induced between the plates. The magnitude of the vortex is linear to the difference in the accommodation coefficients. When both plates have a wave-like distribution of the accommodation coefficients, a one-way flow through the channel between the plates is induced. This flow depends on the phase difference of the discontinuity point. The size of one-way flow is nonlinear to the difference in accommodation coefficients.
28
Sun, Qisong, Junguo Hu, Junjie Jiang, et al. "Effect of Soil Volumetric Water Content on the CO2 Diffusion Coefficient." Sustainability 15, no. 16 (2023): 12637. http://dx.doi.org/10.3390/su151612637.
Full textAbstract:
Purpose: The soil air diffusion coefficient (Ds) is particularly important for the study of soil gas diffusion movement, and there are still many uncertainties in the widely used methods; as such, a method was designed to in situ measure the soil gas diffusion coefficient. Methods: Four different soil media were selected and studied by means of a designed in situ measurement of soil gas diffusion coefficients, and these were compared and analyzed with the predictions of several commonly used prediction models. In addition, they were combined with gas transport models to validate the results of the empirical models that were obtained by the in situ measurements. Results: The results of the data indicate that increasing the volumetric soil moisture content decreases the soil gas diffusion coefficient, with changes in the soil gas diffusion coefficient for the small-grained quartz sand medium being similar to those predicted by the Buckingham model. The soil gas diffusion coefficients for the large-grained quartz sand were similar to the Millington and Quirk model predictions at low humidity; for increased humidity, it was instead similar to the Buckingham model predictions. The soil gas diffusion coefficients of the two active media were closer to those of the SWLR model with high Cm. In addition, the R2 of the measured data was verified, by empirical modeling, to be greater than 0.54, and inversion experiments were conducted to verify that the results were consistent with those of the SWLR model. Conclusion: When measuring relative diffusion coefficients in the field, we recommend the in situ measurement method, which is more reflective of the actual situation in natural environments and provides more accurate data support for soil carbon flux studies.
29
Aousgi, F., S. Hadded, and H. Aroui. "On the Pressure and Temperature Dependence of the Absorption Coefficient of NH3." International Journal of Spectroscopy 2011 (October 31, 2011): 1–7. http://dx.doi.org/10.1155/2011/816548.
Full textAbstract:
The effects of pressure and temperature on the absorption coefficient of ammonia (NH3) gas self-perturbed and perturbed by nitrogen (N2) gas have been measured. We varied the gas pressure from 10 to 160 Torr and the temperature from 235 to 296 K in order to study the absorption coefficient at the center and the wings of lines in the ν4 band of NH3. These measurements were made using a high resolution (0.0038 cm-1) Bruker Fourier-transform spectrometer. These spectra have been analyzed using the method of multipressure technique permitting to succeed to an evolution of the absorption coefficient with the pressure and the quantum numbers J and K of the NH3 molecule. The results show that the absorption coefficient varies as a quadratic function of the pressure at the center of a given line. However, it has a linear evolution in the wings of the line. Moreover, the absorption coefficients are inversely proportional to temperature in the wings when NH3 lines are broadened by N2. The retrieved values of these coefficients were used to derive the temperature dependence of N2 broadening NH3 lines. The absorption coefficients were shown to fit closely the well-known exponential law.
30
Elesin, Andrey V., Alfiya Sh Kadyrova, and Anatoly I. Nikiforov. "Identification of the permeability field for three-dimensional reservoir using the results of geophysical well survey." Georesursy 23, no. 1 (2021): 106–11. http://dx.doi.org/10.18599/grs.2021.1.11.
Full textAbstract:
A model problem of the permeability field identification for a three-dimensional reservoir opened by a large number of wells in the conditions of stationary single-phase fluid filtration is considered. The permeability field is determined in the process of solving the inverse coefficient problem by on known values of bottomhole pressure. The solving problem algorithm is constructed so that the proportionality coefficients of the layers permeability on wells obtained from the results of geophysical well survey are preserved. The influence of various types of errors on the identification results is studied.
31
Oguejiofor, J. Obi, and Jacinta Ifeoma Obidile. "Effects of Computer-aided Instruction on Students’ Performance in Use of English in Tertiary Institutions in Anambra State, Nigeria." Global Journal of Arts, Humanities and Social Sciences 11, no. 10 (2023): 58–68. http://dx.doi.org/10.37745/gjahss.2013/vol11n105868.
Full textAbstract:
The research departs from the realization that technological advancement, especially Information and Communication Technology (ICT) is greatly changing the process of teaching and learning, in higher institutions. While this process of change may not yet be so speedy in Nigeria, there is no doubt that the traditional or conventional teaching process is gradually giving way, and the ICT based teaching is setting into the fora of higher education. Using the quasi-experimental design involving pretest, posttest and non-randomized control and experimental groups, the study examined the achievement scores of students taught Use of English using computer-assisted instruction (CAI) and conventional method of teaching. The population of the study comprised all the year one students offering the Use of English. The sample of the study consisted of one thousand and eighteen students drawn from two Universities in Anambra State. Two research questions guided the study and three null hypotheses were tested at 0.05 level significance. The instrument for data collection was Use of English Achievement Test (UEAT) made up of 30 multiple choice test items with four options (A-D) from GSS 101 curriculum. The instrument was validated by three experts and a reliability coefficient of 0.80 was obtained using Kuder-Richardson Formula 20. Data collected were analyzed using mean scores to answer the research questions and Analysis of Covariance (ANCOVA) to test the null hypotheses. Findings revealed a significant difference in the post test scores of students in the control group and experimental group. Although, students in the experimental group (taught Use of English using CAI) had higher mean scores than their counterparts taught using the conventional method of teaching. Also there was no significant difference in the mean scores of male and female students taught Use of English using CAI. Based on the findings it was recommended that Computer-Assistant Instruction should be encouraged in the teaching and learning of Use of English.
32
Hayder Abd Al-kaream Muhsin. "EXPERIMENTAL STUDY OF LIQUID DISPERSION IN BUBBLE COLUMN." Diyala Journal of Engineering Sciences 1, no. 1 (2008): 56–85. http://dx.doi.org/10.24237/djes.2008.01105.
Full textAbstract:
The main object of this study is to investigate the influence of column diameter and superficial gas velocity on liquid phase dispersion coefficients (axial and radial dispersion coefficients), mixing times, gas holdup, and bubble dynamics (bubble diameter and rise velocity). The liquid phase dispersion, gas holdup, and bubble dynamics (Db and Vb0) were measured for the air-water system in bubble columns of two different diameters,15 and 30 cm. The superficial gas velocity, Ug, was varied in the range 1-10 cm/s, spanning both the homogeneous and heterogeneous flow regimes. The height of liquid in the column was kept constant at 130 cm for the two column. Axial and radial dispersion coefficients and mixing times were measured at various axial and radial locations inside the columns (Z = 25, 75, 125 cm and r/R = 0, 0.45, 0.85), bubble dynamics were measured at three axial location (Z=25, 75, 125 cm). From the experimental data it was found that, the value of the radial dispersion coefficient (Dr,L) and axial dispersion coefficient (Dax,L), gas holdup, bubble diameter and bubble rise velocity, increase with increasing superficial gas velocity. The results emphasise the significant influence of the column diameter on the hydrodynamics. Gas holdup showed a decrease with increasing column diameter, while the radial dispersion coefficient (Dr,L), axial dispersion coefficient (Dax,L), bubble diameter and bubble rise velocity increased with increasing column diameter. A statistical analysis was performed to get a general correlations for the axial liquid dispersion coefficient as a function of the mixing time and dispersion height (Hd), this correlations are: Dax,L=0.15 H2d /θ0.3 for 30 cm column diameter and Dax,L=0.11 H2d /θ0.3 for 15 cm column diameter.
33
Maciuk, Kamil. "DOP coefficients in GNSS observations." Budownictwo i Architektura 14, no. 1 (2015): 065–72. http://dx.doi.org/10.35784/bud-arch.1668.
Full textAbstract:
Integrated GNSS (GPS+GLONASS) satellite measurements carry a number of benefits. The main advantages are especially possibilities of conducting measurements in areas where use of a single satellite system was not impossible so far. In this paper number of visible satellites and DOP coefficients values in terms artificial horizon obstacles were analysed. Paper also discusses benefits of including additional observations from other navigation satellite systems.
34
Li, Jiming, David Ransom, Luis San Andre´s, and John Vance. "Comparison of Predictions With Test Results for Rotordynamic Coefficients of a Four-Pocket Gas Damper Seal." Journal of Tribology 121, no. 2 (1999): 363–69. http://dx.doi.org/10.1115/1.2833948.
Full textAbstract:
Experiments and field applications have demonstrated that multiple-pocket gas damper seals effectively eliminate subsynchronous vibration and attenuate imbalance response at the critical speeds in turbomachinery. A one-control volume, turbulent bulk-flow model for the prediction of the seal leakage and rotordynamic force coefficients of centered multiple-pocket damper seals is hereby detailed. Comparisons of numerical predictions with experimental force coefficients for a four-pocket damper seal are presented. The bulk-flow model and experiments indicate the seal direct stiffness and damping force coefficients are insensitive to journal speed while the cross-coupled stiffnesses increase slightly. However, the current model overpredicts the direct damping coefficient and underpredicts the direct stiffness coefficient for increasing test pressure ratios. Computed results show that the force coefficients of multiple-pocket gas damper seals are also functions of the rotor excitation frequency.
35
Tofig, Samadov, Novruzova Sudaba, and Samadzade Adil. "PROGNOSIS OF HYDROCARBON RECOVERY COEFFICIENTS OF OFFSHORE GAS AND GAS-CONDENSATE FIELDS." Technology audit and production reserves 4, no. 2 (48) (2019): 34–37. https://doi.org/10.15587/2312-8372.2019.180542.
Full textAbstract:
<em>One of the main and important sections of the offshore gas and gas condensate field’s development project is the forecast of hydrocarbon recovery coefficient. The most accurate forecast of the hydrocarbon recovery factor of offshore gas and gas condensate deposits is of particular importance for the quality management of their development processes through the timely establishment and implementation of the necessary priority measures. In view of this, the object of research is prediction of hydrocarbon recovery of offshore gas and gas condensate deposits at different stages of their development. The task of selection of models of prediction of coefficients of current and final gas and condensate recovery of sea gas and gas condensate deposits is investigated by creation of special models of their determination for different periods before watering. It is noted that for long-term gas and gas condensate fields, the use of evolutionary models is more efficient and efficient for accurate forecasting of recoverable gas reserves at certain stages of development. Evolutionary models were constructed in two stages – preliminary analysis stage (training interval) and prediction stage (examination interval). As a result of the research, reliable models are proposed for forecasting the coefficients of current and final gas and condensate recovery of offshore gas and gas condensate deposits by different stages of development. A distinctive feature of this definition of hydrocarbon recovery field coefficient prediction models is the use of balance and recoverable deposit reserves data for different stages of development. The study used geological and field data on the VII horizon of the Sangachal-Sea-Duvanna-Sea-Hara-Zira field (Azerbaijan). On the basis of selected mathematical models, coefficients of current and final hydrocarbon recovery can be determined at different stages and efficiency of the process of development of deposits can be estimated. The obtained results will create opportunities to control the development strategy of the deposit and to select the optimal method of determining geological and technical measures used to increase the coefficient of final hydrocarbon recovery</em>
36
Hu, Wulong, Yao Jiang, Daoyi Chen, Yongshui Lin, Qiang Han, and Yifei Cui. "Impact of Pore Geometry and Water Saturation on Gas Effective Diffusion Coefficient in Soil." Applied Sciences 8, no. 11 (2018): 2097. http://dx.doi.org/10.3390/app8112097.
Full textAbstract:
Gas flow in soil plays a crucial role in terrestrial ecosystems, and numerical simulation of their movement needs to know their effective diffusion coefficients. How pore structure influences the effective diffusion coefficient has been studied intensively for dry porous media, but much remains unknown for unsaturated soils. Here, we employed the X-ray tomography technique at the pore scale to directly obtain the soil structures, the geometry of their pores and the water distribution under different water saturation levels were calculated using a morphological model. The results show that pore structures including porosity, interface area of gas–solid–water and pore diameter are closely related to water saturation. The increase of mean pore diameter with gas saturation can be fitted into a power law. We also investigated the impact of pore geometry and water saturation on the effective diffusion coefficients, which is independent of the molecular mass of gas after normalization. As the normalized effective Knudsen diffusion coefficient increases with average pore diameter following a power law, with the scaling factor related to pore geometry and the exponent is a constant, we explained and proved that the Knudsen diffusion coefficient increases with gas saturation, also following a power law.
37
Ahmed, Abubakar S., Murtala Ahmed, and Aliyu Bello. "Molecular Dynamics Simulation Study of the Diffusion of Carbon Dioxide in Heptane: Application in Natural Gas Cleaning." Journal of Chemical Engineering and Industrial Biotechnology 9, no. 2 (2023): 48–57. http://dx.doi.org/10.15282/jceib.v9i2.9495.
Full textAbstract:
Using solvents to remove carbon dioxide is an effective way to purify natural gas. Diffusion of solute in solvent is key to natural gas purification. In this study, molecular dynamics (MD) simulations of the diffusion of carbon dioxide in heptane at different temperatures and pressures were performed to simulate the conditions of industrial purification process. The diffusion coefficients were measured in two different configurations; pure solvent and binary solute-solvent systems. The diffusion coefficients of the binary system were observed to be in the order of 10-9 m2/s. An increased temperature was observed to increase the diffusion coefficient of the carbon dioxide in heptane while an increase in pressure reduced the value of the diffusion coefficient. The diffusion coefficient was also observed to follow an Arrhenius-type relationship with respect to temperature. The activation energy of the system increased from 9.228 kJ/mol to 11.139 kJ/mol with pressure increase. A linear relationship was detected between the diffusion coefficient and the viscosity of the system and an increased viscosity of the system results in a decreased diffusion coefficient. The results of the research showed that carbon dioxide behavior in heptane offers the theoretical backing for the development of a new natural gas desulphurization solvent.
38
Zhu, Wei Yao, Zhen Zhang, and Jia Deng. "Gas Flow Mechanism in Tight Reservoir and Productivity Prediction Model of Fractured Wells." Advanced Materials Research 868 (December 2013): 711–17. http://dx.doi.org/10.4028/www.scientific.net/amr.868.711.
Full textAbstract:
Flow mechanism in tight reservoir is different from that in normal reservoir because of the nanoscale and micro-scale holes in the reservoir. Beskok-Karniadakis model can describe gas diffusion and flow. In this paper, Beskok-Karniadakis model was applied and optimized in consideration of the tight gas productivity influenced by both Knudsen diffusion and desorption. Furthermore, tight gass productivity of fractured vertical wells was obtained with the method of permeability resistance. In combination of examples and theory, the influence of diffusion coefficient, half-length of fractures and fracture conductivity on well gas productivity was analyzed. The results show that free gas has a close connection with total productivity. Diffusion coefficients are not the same in different reservoir, and this can also influence the productivity. For fracture conductivity, the productivity goes up with the fracture conductivity increases. A method to provide guidance of effective productivity is gotten with optimizing the conductivity.
39
D’Souza, Rohan J., and Dara W. Childs. "A Comparison of Rotordynamic-Coefficient Predictions for Annular Honeycomb Gas Seals Using Three Different Friction-Factor Models." Journal of Tribology 124, no. 3 (2002): 524–29. http://dx.doi.org/10.1115/1.1456086.
Full textAbstract:
A two-control-volume bulk-flow model is used to predict rotordynamic coefficients for an annular, honeycomb-stator/smooth-rotor gas seal. The bulk-flow model uses Hirs’ turbulent-lubrication model, which requires a friction factor model to define the shear stresses at the rotor and stator wall. Rotordynamic coefficients predictions are compared for the following three variations of the Blasius pipe-friction model: (i) a basic model where the Reynolds number is a linear function of the local clearance, fs=ns Rems (ii) a model where the coefficient is a function of the local clearance, and (iii) a model where both the coefficient and exponent are functions of the local clearance. The latter models are based on data that shows the friction factor increasing with increasing clearances. Rotordynamic-coefficient predictions shows that the friction-factor-model choice is important in predicting the effective-damping coefficients at a lower frequency range (60∼70 Hz) where industrial centrifugal compressors and steam turbines tend to become unstable. At a higher frequency range, irrespective of the friction-factor model, the rotordynamic-coefficient predictions tend to coincide. Blasius-based Models which directly account for the observed increase in stator friction factors with increasing clearance predict significantly lower values for the destabilizing cross-coupled stiffness coefficients.
40
Szpunar, Tadeusz, and Paweł Budak. "Sposoby uaktualniania charakterystyki wydobywczej odwiertu gazowego przez okresową modyfikację wielkości współczynnika przepływu laminarnego." Nafta-Gaz 76, no. 4 (2020): 239–48. http://dx.doi.org/10.18668/ng.2020.04.03.
Full text
41
Peng, J. P., and M. Carpino. "Calculation of Stiffness and Damping Coefficients for Elastically Supported Gas Foil Bearings." Journal of Tribology 115, no. 1 (1993): 20–27. http://dx.doi.org/10.1115/1.2920982.
Full textAbstract:
The stiffness and damping coefficients of an elastically supported gas foil bearing are calculated. A perfect gas is used as the lubricant, and its behavior is described by the Reynolds equation. The structural model consists only of an elastic foundation. The fluid equations and the structural equations are coupled. A perturbation method is used to obtain the linearized dynamic coefficient equations. A finite difference formulation has been developed to solve for the four stiffness and the four damping coefficients. The effect of the bearing compliance on the dynamic coefficients is discussed in this paper.
42
Ma, Ce, Eric Shero, Nishith Verma, Stephen Gilbert, and Farhang Shadman. "Permeation of Moisture and Oxygen Through Polymeric O-Rings." Journal of the IEST 38, no. 2 (1995): 43–46. http://dx.doi.org/10.17764/jiet.2.38.2.k6491358g0l83691.
Full textAbstract:
The permeation coefficients of H2O and O2 through polymeric O-rings were obtained in this study. Increases of trace level impurities in an ultra-high purity nitrogen purge gas due to the permeation processes were measured using an atmospheric pressure ionization mass spectrometer (APIMS). In this paper, the experimental results of nine different O-ring samples (Kalrez, Chemraz, Teflon, Vespel, Viton) are reported. The Kalrez "wet" O-ring showed the lowest moisture permeation coefficient of 1.5×-1010 [cm3 gas(STP). cm polymer]/[cm2 polymer · sec · torr] and Vespel displayed the lowest oxygen permeation coefficient of 0.01×-1010 [cm3 gas(STP) · cm polymer]/[cm2 polymer · sec · torr] and room temperature. In addition, permeation coefficients at 50°C and 75°C are presented. The activation energies varied from about 18 to 51 kJ/mole/°K for both H2O and O2.
43
Younis, M. A. "New Approach to Determine the Heat+transfer Coefficients for Cooling Tower Packing." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 203, no. 2 (1989): 75–84. http://dx.doi.org/10.1243/pime_proc_1989_203_193_02.
Full textAbstract:
The heat input response technique was developed to determine the heat-transfer coefficients for a forced draught cooling tower packing. The method was applied to a counter current type air-water contact system in a packed bed. A temperature change was alternately imposed on inlet air at the tower bottom and on inlet water at the tower top. Outlet temperatures of air and water were measured with time. From zeroth moments of these temperature changes, water-film and air-film heat-transfer coefficients have been estimated. Finally, the effect of the water/air loading ratio and the packing material, such as wood, aluminium wire netting and plastic PVC on the values of the heat-transfer coefficients was experimentally tested. An empirical relationship between the gas-side heat-transfer coefficient, liquid-side heat-transfer coefficient and water/gas ratio has been established within the range of the tested data.
44
Wang, Chun-Hung, K. R. V. Manikantachari (Raghu), Artëm E. Masunov, and Subith S. Vasu. "Determination of the Diffusion Coefficients of Binary CH4 and C2H6 in a Supercritical CO2 Environment (500–2000 K and 100–1000 atm) by Molecular Dynamics Simulations." Energies 17, no. 16 (2024): 4028. http://dx.doi.org/10.3390/en17164028.
Full textAbstract:
The self-diffusion coefficients of carbonaceous fuels in a supercritical CO2 environment provide transport information that can help us understand the Allam Cycle mechanism at a high pressure of 300 atm. The diffusion coefficients of pure CO2 and binary CO2/CH4 and CO2/C2H6 at high temperatures (500 K~2000 K) and high pressures (100 atm~1000 atm) are determined by molecular dynamics simulations in this study. Increasing the temperature leads to an increase in the diffusion coefficient, and increasing the pressure leads to a decrease in the diffusion coefficients for both methane and ethane. The diffusion coefficient of methane at 300 atm is approximately 0.012 cm2/s at 1000 K and 0.032 cm2/s at 1500 K. The diffusion coefficient of ethane at 300 atm is approximately 0.016 cm2/s at 1000 K and 0.045 cm2/s at 1500 K. The understanding of diffusion coefficients potentially leads to the reduction in fuel consumption and minimization of greenhouse gas emissions in the Allam Cycle.
45
Nguyen, Tien-Quang, Maja Glorius, and Cornelia Breitkopf. "A New Approach to Determine Gas Diffusion Coefficients in Porous Solids by EIS: Application for NH3 and CO2 Adsorption on Zirconia and Zeolite Type 5A." Advances in Mathematical Physics 2018 (October 4, 2018): 1–11. http://dx.doi.org/10.1155/2018/5462659.
Full textAbstract:
A new theoretical approach has been established to define transport coefficients of charge and mass transport in porous materials directly from impedance data; thus four transport coefficients could be determined. In case of ammonia adsorption on sulfated zirconia, the diffusion coefficient was figured out to be approximately the mobility diffusion coefficient of ammonium ions: 1.2 x 10-7 cm2/s. The transport of carbon dioxide was examined for samples of zeolite type 5A in different hydration states. By impedance spectroscopy measurements, the diffusion coefficient of water vapor at 373 K is estimated to be about 7 x 10-6 cm2/s. The influence of carbon dioxide adsorption on diffusion coefficients is studied based on two pellet types of zeolite 5A. The difference between polar and non-polar gas adsorption in porous solids is considered as changed characteristic of impedance.
46
Wu, Yao, Lihua Yang, Tengfei Xu, and Haoliang Xu. "Combined Effect of Rarefaction and Effective Viscosity on Micro-Elasto-Aerodynamic Lubrication Performance of Gas Microbearings." Micromachines 10, no. 10 (2019): 657. http://dx.doi.org/10.3390/mi10100657.
Full textAbstract:
Elastic deformation and gaseous rarefaction effects are of great importance to the static and dynamic characteristics of gas microbearings. Based on the effective viscosity model of Veijola, the governing equations can be solved by the partial derivative method, finite element procedure, and relaxed iterative algorithm. The numerical results showed that the maximum gas pressure is relatively lower compared to a microbearing with a rigid liner at a local pressure peak region, owing to the film thickness of two converging-diverging profiles and the existence of bimodal pressure inside the elastic microbearing liner. However, the effect of bearing flexibility provides a marginal increase in the load capacity on account of the integral area of pressure distribution is larger than the rigid bearing liner. The friction coefficient and direct stiffness coefficients increase as the elastic modulus decreases while the direct damping coefficients become smaller at high eccentricity ratios and bearing numbers. Since the Poiseuille flow rate increases in connection with an increasing Knudsen number, the effective viscosity of the lubricant leads to a decreased load carrying capacity, friction coefficient, and direct stiffness coefficient, which produces an increase in the direct damping coefficients.
47
Angura, Michael Terfa, Joseph Olaiya Fatoki, Veronica Enemarie, and B. A. Fakolade. "Constraints Militating against Effective Implementation of the 3-Year Upper Basic Science and Technology Curriculum in Nigeria." VillageMath Educational Review (VER) 3, no. 1 (2022): 205–18. https://doi.org/10.5281/zenodo.6372095.
Full textAbstract:
This study examined the constraints militating against effective implementation of the 3-year Upper Basic Science and Technology curriculum in North Central Nigeria. It employed a cross sectional survey design. The population comprised all 10,688 Basic Science and Technology teachers in North Central Nigeria. The sample consisted of 288 teachers randomly selected from 72 government and private secondary schools in the study area. Basic Science and Technology Teachers Questionnaire (BSTTQ) was used for data collection. The instrument was validated by three experts, two in Science Education and one in Test and Measurement. The reliability coefficient of the instrument was determined using Cronbach alpha and the measure of internal consistence of instrument was obtained as 0.89. The three research questions which guided the study were answered using mean and standard deviation, while the three null hypotheses were tested at 0.05 level of significance using t-test. The findings revealed that teacher related constraints such as number of unqualified teachers, nonpayment of salaries among others, militates against effective implementation of the curriculum in government secondary schools (GSS) to great extent, while the same constraints affect the implementation of the curriculum in private secondary schools (PSS) moderately. In the same way, instructional materials and facilities constraints the effective implementation of the 3-year Upper Basic Science and Technology curriculum in government schools to a great extent compared to private secondary schools that are affected moderately. It was recommended based on the findings that the government through the Ministry of Education (MOE) and State Universal Basic Education Boards (SUBEB) should ensure that the teacher-related constraints that hinder effective implementation of the curriculum are solved especially in government secondary schools by employing more qualified teachers in the four areas of the subject. More instructional materials such as projectors, instructional television, and internet should be provided especially in government secondary schools for effective implementation of the curriculum. Also more facilities such as furniture, workshops and laboratories should be provided to a great extent in both government and private secondary schools, if actually the 3-year Upper Basic Science and Technology curriculum is to be implemented effectively in Nigeria.
48
Amani, Mohamad, and Arezoo Safaviyan. "Sub-Basins Prioritization Using Morphometric Analysis-Remote Sensing Technique and GIS-Golestan-Iran." International Letters of Natural Sciences 38 (May 2015): 56–65. http://dx.doi.org/10.18052/www.scipress.com/ilns.38.56.
Full textAbstract:
Sub-basins prioritization is one of the most important resolutions of development sustainability and natural resources comprehended management. In this study, 11 sub-basins of Lohender in east Golstan province about 272/63cm Prioritized using computation and morphometric analysis and using GIS and RS techniques. Erosion mode in each sub-basin specified through Sediment Yield Index approximation. In morphometric analysis, parameters like canal length, bifurcation ratio, discharge density, sub-basins shape coefficient, round coefficient, stretch coefficient and compressive coefficients were computed thus these parameters divided to two classifications: linear coefficients and figurative coefficient. In order to study annual sediment index, from fields applied maps, land coverage, slope, soil type and topographic map scale 1:50000 were used. Finally, each sub-basin Priority determined due to Sediment Yield Index (SYI) and total average of morphometric parameters. According to morphometric parameters, the BS sub-basin and according to SYI parameter, A5 sub-basin showed more critical mode and combination of both showed that B2 sub-basin showed the worst situation.
49
Amani, Mohamad, and Arezoo Safaviyan. "Sub-Basins Prioritization Using Morphometric Analysis-Remote Sensing Technique and GIS-Golestan-Iran." International Letters of Natural Sciences 38 (May 6, 2015): 56–65. http://dx.doi.org/10.56431/p-21x716.
Full textAbstract:
Sub-basins prioritization is one of the most important resolutions of development sustainability and natural resources comprehended management. In this study, 11 sub-basins of Lohender in east Golstan province about 272/63cm Prioritized using computation and morphometric analysis and using GIS and RS techniques. Erosion mode in each sub-basin specified through Sediment Yield Index approximation. In morphometric analysis, parameters like canal length, bifurcation ratio, discharge density, sub-basins shape coefficient, round coefficient, stretch coefficient and compressive coefficients were computed thus these parameters divided to two classifications: linear coefficients and figurative coefficient. In order to study annual sediment index, from fields applied maps, land coverage, slope, soil type and topographic map scale 1:50000 were used. Finally, each sub-basin Priority determined due to Sediment Yield Index (SYI) and total average of morphometric parameters. According to morphometric parameters, the BS sub-basin and according to SYI parameter, A5 sub-basin showed more critical mode and combination of both showed that B2 sub-basin showed the worst situation.
50
Mathias, Simon A., Marco Dentz, and Qingquan Liu. "Gas Diffusion in Coal Powders is a Multi-rate Process." Transport in Porous Media 131, no. 3 (2019): 1037–51. http://dx.doi.org/10.1007/s11242-019-01376-x.
Full textAbstract:
AbstractGas migration in coal is strongly controlled by surface diffusion of adsorbed gas within the coal matrix. Surface diffusion coefficients are obtained by inverse modelling of transient gas desorption data from powdered coals. The diffusion coefficient is frequently considered to be dependent on time and initial pressure. In this article, it is shown that the pressure dependence can be eliminated by performing a joint inversion of both the diffusion coefficient and adsorption isotherm. A study of the log–log slope of desorbed gas production rate against time reveals that diffusion within the individual coal particles is a multi-rate process. The application of a power-law probability density function of diffusion rates enables the determination of a single gas diffusion coefficient that is constant in both time and initial pressure.