scholarly journals Parametric Study of Fuel Distribution Effects on a Kerosene-Based Scramjet Combustor

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Jun Yang ◽  
Xian-yu Wu ◽  
Zhen-guo Wang
Keyword(s):  
Parametric Study ◽  
Equivalence Ratio ◽  
Interaction Analysis ◽  
Objective Functions ◽  
Model Interaction ◽  
Fuel Distribution ◽  
Scramjet Combustor ◽  
Distribution Scheme ◽  
Overall Performance ◽  
The Impact

Generally, the overall performance of scramjet combustor is greatly impacted by the fuel distribution scheme. The current paper mainly conducted a comprehensive parametric study of the impact of fuel distribution on the overall performance of a kerosene-based scramjet combustor. Herein, a 3D supersonic combustor with a recessed cavity and four injection orifices was taken into consideration. The combustor’s performance was analyzed by 3D RANS model. The fuel equivalence ratio for each injection port was taken as the design variables. And the combustion efficiency, the total pressure recovery coefficient, and the drag coefficient were chosen as the objective functions. Some novel data mining methods including DOE technique, Kriging approximation model, interaction analysis, and main effects analysis methods were employed to conduct the parametric study. The distributed fuel injection scheme was optimized by nondominated sorting genetic algorithm. The results show that three objective functions were remarkably affected by both of the total fuel equivalence ratio and the fuel distribution scheme. The objective functions cannot reach the optimal solution at the same time, and there must be a tradeoff among the objective functions.

The Impact of Bar Service Operation Practices on Organizational Performance in Indian Hotel Industry

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohinder C. Dhiman ◽  
Abhishek Ghai
Keyword(s):  
Organizational Performance ◽  
Hotel Industry ◽  
Demographic Variables ◽  
Study Results ◽  
Service Operation ◽  
Managerial Implications ◽  
Overall Performance ◽  
The Impact ◽  
The Relationship ◽  
Bivariate Test

The paper has a two fold purpose - examine the impact of bar service operation practices (BSOP) on organizational performance (OP) and study the relationship between organizational performance and demographic variables. Based on a survey of 362 bar managers perceptions on the impact of bar service operation practices on organizational performance were assessed by 59 practices and 6 demographic variables. Bivariate test and ANOVA were employed to test the working hypothesis in the study. Results indicated that there is a positive relationship between the bar service operation practices and organizational performance. Further, the results indicate some practical and managerial implications to improve organizational overall performance.

A Fracture Mechanics Based Parametric Study of the Copper-to-Copper Direct Thermo-Compression Bonded Interface Using Finite Element Method

2013 ◽  
Author(s):  
Ah-Young Park ◽  
Satish Chaparala ◽  
Seungbae Park
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Parametric Study ◽  
Initial Crack ◽  
Bonding Interface ◽  
Interface Condition ◽  
Large Temperature ◽  
Bonded Interface ◽  
The Impact ◽  
Element Method

Through-silicon via (TSV) technology is expected to overcome the limitations of I/O density and helps in enhancing system performance of conventional flip chip packages. One of the challenges for producing reliable TSV packages is the stacking and joining of thin wafers or dies. In the case of the conventional solder interconnections, many reliability issues arise at the interface between solder and copper bump. As an alternative solution, Cu-Cu direct thermo-compression bonding (CuDB) is a possible option to enable three-dimension (3D) package integration. CuDB has several advantages over the solder based micro bump joining, such as reduction in soldering process steps, enabling higher interconnect density, enhanced thermal conductivity and decreased concerns about intermetallic compounds (IMC) formation. Critical issue of CuDB is bonding interface condition. After the bonding process, Cu-Cu direct bonding interface is obtained. However, several researchers have reported small voids at the bonded interface. These defects can act as an initial crack which may lead to eventual fracture of the interface. The fracture could happen due to the thermal expansion coefficient (CTE) mismatch between the substrate and the chip during the postbonding process, board level reflow or thermal cycling with large temperature changes. In this study, a quantitative assessment of the energy release rate has been made at the CuDB interface during temperature change finite element method (FEM). A parametric study is conducted to analyze the impact of the initial crack location and the material properties of surrounding materials. Finally, design recommendations are provided to minimize the probability of interfacial delamination in CuDB.

scholarly journals Impact of Dataset Size on Classification Performance: An Empirical Evaluation in the Medical Domain

2021 ◽  
Vol 11 (2) ◽  
pp. 796
Author(s):  
Alhanoof Althnian ◽  
Duaa AlSaeed ◽  
Heyam Al-Baity ◽  
Amani Samha ◽  
Alanoud Bin Dris ◽  
...  
Keyword(s):  
Empirical Evaluation ◽  
Classification Performance ◽  
Support Vector ◽  
Robust Model ◽  
Original Distribution ◽  
C4.5 Decision Tree ◽  
Dataset Size ◽  
Overall Performance ◽  
Medical Domain ◽  
The Impact

Dataset size is considered a major concern in the medical domain, where lack of data is a common occurrence. This study aims to investigate the impact of dataset size on the overall performance of supervised classification models. We examined the performance of six widely-used models in the medical field, including support vector machine (SVM), neural networks (NN), C4.5 decision tree (DT), random forest (RF), adaboost (AB), and naïve Bayes (NB) on eighteen small medical UCI datasets. We further implemented three dataset size reduction scenarios on two large datasets and analyze the performance of the models when trained on each resulting dataset with respect to accuracy, precision, recall, f-score, specificity, and area under the ROC curve (AUC). Our results indicated that the overall performance of classifiers depend on how much a dataset represents the original distribution rather than its size. Moreover, we found that the most robust model for limited medical data is AB and NB, followed by SVM, and then RF and NN, while the least robust model is DT. Furthermore, an interesting observation is that a robust machine learning model to limited dataset does not necessary imply that it provides the best performance compared to other models.

Characteristics of Flame Bases for V-Gutters Stabilized Premixed Flames

2013 ◽  
Author(s):  
Fan Gong ◽  
Yong Huang
Keyword(s):  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Equivalence Ratio ◽  
Premixed Flames ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Heat Conducting ◽  
Inlet Velocity ◽  
The Impact

The objective of this work is to investigate the flame stabilization mechanism and the impact of the operating conditions on the characteristics of the steady, lean premixed flames. It’s well known that the flame base is very important to the existence of a flame, such as the flame after a V-gutter, which is typically used in ramjet and turbojet or turbofan afterburners and laboratory experiments. We performed two-dimensional simulations of turbulent premixed flames anchored downstream of the heat-conducting V-gutters in a confined passage for kerosene-air combustion. The flame bases are symmetrically located in the shear layers of the recirculation zone immediately after the V-gutter’s trailing edge. The effects of equivalence ratio of inlet mixture, inlet temperature, V-gutter’s thermal conductivity and inlet velocity on the flame base movements are investigated. When the equivalence ratio is raised, the flame base moves upstream slightly and the temperature gradient dT/dx near the flame base increases, so the flame base is strengthened. When the inlet temperature is raised, the flame base moves upstream very slightly, and near the flame base dT/dx increases and dT/dy decreases, so the flame base is strengthened. As the V-gutter’s thermal conductivity increases, the flame base moves downstream, and the temperature gradient dT/dx near the flame base decreases, so the flame base is weakened. When the inlet velocity is raised, the flame base moves upstream, and the convection heat loss with inlet mixture increases, so the flame base is weakened.

The impact of counterfeit risk management on healthcare supply chain performance: an empirical analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mauro Falasca ◽  
Scott Dellana ◽  
William J. Rowe ◽  
John F. Kros
Keyword(s):  
Risk Management ◽  
Supply Chain ◽  
The United States ◽  
Equation Modeling ◽  
Significant Positive Effect ◽  
Healthcare Organizations ◽  
Content Type ◽  
Overall Performance ◽  
The Impact ◽  
Positive Effect

PurposeThis study develops and tests a model exploring the relationship between supply chain (SC) counterfeit risk management and performance in the healthcare supply chain (HCSC).Design/methodology/approachIn the proposed theoretical model, HCSC counterfeit risk management is characterized by HCSC counterfeit risk orientation (HCRO), HCSC counterfeit risk mitigation (HCRM) and HCSC risk management integration (HRMI), while performance is represented by healthcare logistics performance (HLP) and healthcare organization overall performance (HOP). Partial least squares structural equation modeling (PLS-SEM) and survey data from 55 HCSC managers are used to test the research hypotheses.FindingsHCRO has a significant positive effect on HCRM, while HCRM has a positive impact on HRMI. With respect to HLP, HCRM has a nonsignificant effect, while HRMI has a significant impact, thus confirming the important mediating role of HRMI. Finally, HLP has a significant positive effect on the overall performance of healthcare organizations.Research limitations/implicationsAll study participants were from the United States, limiting the generalizability of the study findings to different countries or regions. The sample size employed in the study did not allow the authors to distinguish among the different types of healthcare organizations.Originality/valueThis study delineates between a healthcare organization's philosophy toward counterfeiting risks vs actions taken to eliminate or reduce the impact of counterfeiting on the HCSC. By offering firm-level guidance for managers, this study informs healthcare organizations about addressing the challenge of counterfeiting in the HCSC.

Describing the Mechanism of Instability Suppression Using a Central Pilot Flame With Coupled Experiments and Simulations

2021 ◽  
Author(s):  
Jihang Li ◽  
Hyunguk Kwon ◽  
Drue Seksinsky ◽  
Daniel Doleiden ◽  
Jacqueline O’Connor ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Equivalence Ratio ◽  
Vortex Breakdown ◽  
Eddy Simulation ◽  
Breakdown Region ◽  
Large Eddy ◽  
Rate Oscillations ◽  
Combustion Oscillation ◽  
The Stability ◽  
The Impact

Abstract Pilot flames are commonly used to extend combustor operability limits and suppress combustion oscillations in low-emissions gas turbines. Combustion oscillations, a coupling between heat release rate oscillations and combustor acoustics, can arise at the operability limits of low-emissions combustors where the flame is more susceptible to perturbations. While the use of pilot flames is common in land-based gas turbine combustors, the mechanism by which they suppress instability is still unclear. In this study, we consider the impact of a central jet pilot on the stability of a swirl-stabilized flame in a variable-length, single-nozzle combustor. Previously, the pilot flame was found to suppress the instability for a range of equivalence ratios and combustor lengths. We hypothesize that combustion oscillation suppression by the pilot occurs because the pilot provides hot gases to the vortex breakdown region of the flow that recirculate and improve the static, and hence dynamic, stability of the main flame. This hypothesis is based on a series of experimental results that show that pilot efficacy is a strong function of pilot equivalence ratio but not pilot flow rate, which would indicate that the temperature of the pilot gases as well as the combustion intensity of the pilot flame play more of a role in oscillation stabilization than the length of the pilot flame relative to the main flame. Further, the pilot flame efficacy increases with pilot flame equivalence ratio until it matches the main flame equivalence ratio; at pilot equivalence ratios greater than the main equivalence ratio, the pilot flame efficacy does not change significantly with pilot equivalence ratio. To understand these results, we use large-eddy simulation to provide a detailed analysis of the flow in the region of the pilot flame and the transport of radical species in the region between the main flame and pilot flame. The simulation, using a flamelet/progress variable-based chemistry tabulation approach and standard eddy viscosity/diffusivity turbulence closure models, provides detailed information that is inaccessible through experimental measurements.

scholarly journals ¿Cómo entrenar una habilidad compleja en cirugía?: Evaluación cualitativa de una estrategia basada en simulación

2021 ◽  
Vol 113 (1) ◽  
pp. 101-110
Author(s):  
Juan I. Cobián ◽  
◽  
Federico Ferrero ◽  
Martín P. Alonso ◽  
Alberto M. Fontana
Keyword(s):  
Work Teams ◽  
Technical Skills ◽  
Role Playing ◽  
Professional Activity ◽  
High Fidelity Simulation ◽  
Future Studies ◽  
Raising Awareness ◽  
Simulation Based ◽  
Overall Performance ◽  
The Impact

Background: Learning complex tasks in surgical requires the coordination and integration of technical and non-technical skills have an impact on the performance of work teams. Objective: The aim of this study is to report the results of a simulation-based educational strategy for training in complex surgical skills considering the participants’ perceptions. Material and methods: In 2019, 10 healthcare professionals participated in a 20-hour course divided in 6 hours of online training and 14 hours of onsite training. The strategy designed included the integration of case resolution activities, role-playing, practice with synthetic and virtual simulators and high-fidelity simulation. At the end of the course, a questionnaire was administered to explore participants’ perceptions on what they had learned and on their attitude changes. Results: Fifty percent of the participants perceived their skills and knowledge improved at the end of the course compared with their perception at the beginning of the course while 80% perceived the impact of the course on their professional activity was good or excellent. All the participants agreed with the need for improving non-technical skills. The experience was rated as positive or very positive by all participants, who were eager to repeat it. Conclusion: The participants’ perceptions of this educational program demonstrates that this method is highly accepted. Raising awareness of non-technical skills during the reflection stage suggests the need for changes in attitude and in self-perception of efficacy. We believe that simulation-based training offers the possibility of improving the overall performance of the surgical team. Future studies should focus on this goal.

scholarly journals What impact does postgraduate clinical training have on empathy among Japanese trainee dentists?

2020 ◽  
Author(s):  
Toshiko Yoshida ◽  
Sho Watanabe ◽  
Takayuki Kono ◽  
Hiroaki Taketa ◽  
Noriko Shiotsu ◽  
...  
Keyword(s):  
Clinical Training ◽  
Interaction Analysis ◽  
Healthcare Providers ◽  
Japanese Version ◽  
University Hospital ◽  
Simulated Patients ◽  
Patient Anxiety ◽  
Significant Difference ◽  
Education Support ◽  
The Impact

Abstract Background: Enhancing empathy in healthcare education is a critical component in the development of a relationship between healthcare providers and patients that would ensure better patient care; improved patient satisfaction, adherence to treatment, patients’ medication self-efficacy, improved treatment outcomes, and reduced patient anxiety. Unfortunately, however, the decline of empathy among students has been frequently reported. It is especially common when the curriculum transitions to a clinical setting. However, some studies have questioned the significance and frequency of this decline. Thus, the purpose of this study was to determine the impact of postgraduate clinical training on dental trainees’ empathy from cognitive, behavioral, and patients’ perspective.Methods: This study included 64 trainee dentists at Okayama University Hospital and 13 simulated patients (SPs). The trainee dentists carried out initial medical interviews with SPs twice, at the beginning and the end of their clinical training. The trainees completed the Japanese version of the Jefferson Scale of Empathy for health professionals just before each interview. The SPs evaluated the trainees’ communication using an assessment questionnaire immediately after the interviews. All interviews were videotaped and analyzed using the Roter Interaction Analysis System. The hypothesis was that empathy in the trainees would have reduced at the end of their clinical training. The results were compared between the beginning and the end. The data were analyzed utilizing paired t-test and the Wilcoxon signed-ranks test.Results: No significant difference was found in the self-reported empathy of trainees at the beginning and the end of the clinical training (107.73 vs. 108.34, p=0.643). Similarly, there was no difference in the SPs’ evaluation of trainees’ communication (10.73 vs. 10.38, p=0.434). Communication behavior in the emotional responsiveness category for trainees in the beginning was significantly higher than that at the end (2.47 vs. 1.14, p=0.000).Conclusions: Overall, a one-year postgraduate dental training program neither reduced nor increased trainee dentists’ empathy levels. Providing regular education support in this area may help trainees foster their empathy.

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