scholarly journals Multi-platform app-embedded model for hybrid air-breathing rocket-cycle engine in hypersonic atmospheric ascent

2021 ◽  
pp. 1-23
Author(s):  
S.E. Tsentis ◽  
V.G. Gkoutzamanis ◽  
A.D. Gaitanis ◽  
A.I. Kalfas
Keyword(s):  
Specific Impulse ◽  
Performance Parameters ◽  
Interested Reader ◽  
Component Level ◽  
Air Breathing ◽  
Evaluation Of Performance ◽  
Embedded Model ◽  
The Impact ◽  
Rocket Technology ◽  
Engine Concept

ABSTRACT This paper presents a performance analysis on a novel engine concept, currently under development, in order to achieve hybrid air-breathing rocket technology. A component-level approach has been developed to simulate the performance of the engine at Mach 5, and the thermodynamic interaction of the different working fluids has been analysed. The bypass ramjet duct has also been included in the model. This facilitates the improved evaluation of performance parameters. The impact of ram drag induced by the intake of the engine has also been demonstrated. The whole model is introduced into a multi-platform application for aeroengine simulation to make it accessible to the interested reader. Results show that the bypass duct modelling increases the overall efficiency by approximately 7%. The model calculates the specific impulse at approximately 1800 seconds, which is 4 times higher than any chemical rocket.

scholarly journals Development of a Component-Level Hydrogen Transport Model with OpenFOAM and Application to Tritium Transport Inside a DEMO HCPB Breeder

2021 ◽  
Vol 11 (8) ◽  
pp. 3481
Author(s):  
Volker Pasler ◽  
Frederik Arbeiter ◽  
Christine Klein ◽  
Dmitry Klimenko ◽  
Georg Schlindwein ◽  
...  
Keyword(s):  
Transport Model ◽  
Tritium Concentration ◽  
Minor Role ◽  
Specific Rate ◽  
Component Level ◽  
Diffusion Limited ◽  
Purge Gas ◽  
Choice Of Species ◽  
The Impact ◽  
Tritium Transport

This work continues the development of a numerical model to simulate transient tritium transport on the breeder zone (BZ) level for the EU helium-cooled pebble bed (HCPB) concept for DEMO. The basis of the model is the open-source field operation and manipulation framework, OpenFOAM. The key output quantities of the model are the tritium concentration in the purge gas and in the coolant and the tritium inventory inside the BZ structure. New model features are briefly summarized. As a first relevant application a simulation of tritium transport for a single pin out of the KIT HCPB design for DEMO is presented. A variety of scenarios investigates the impact of the permeation regime (diffusion-limited vs. surface-limited), of an additional hydrogen content of 300 Pa H2 in the purge gas, of the released species (HT vs. T2), and of the choice of species-specific rate constants (recombination constant of HT set twice as for H2 and T2). The results indicate that the released species plays a minor role for permeation. Both permeation and inventory show a considerable dependence on a possible hydrogen addition in the purge gas. An enhanced HT recombination constant reduces steel T inventories and, in the diffusion-limited case, also permeation significantly. Scenarios with 80 bar vs. 2 bar purge gas pressure indicate that purge gas volumetric flow is decisive for permeation.

scholarly journals QiOi: Performance Isolation for Hyperledger Fabric

2021 ◽  
Vol 11 (9) ◽  
pp. 3870
Author(s):  
Jeongsu Kim ◽  
Kyungwoon Lee ◽  
Gyeongsik Yang ◽  
Kwanhoon Lee ◽  
Jaemin Im ◽  
...  
Keyword(s):  
Data Centers ◽  
Component Level ◽  
Isolation Technique ◽  
Cloud Data ◽  
Cpu Scheduling ◽  
Performance Isolation ◽  
Cloud Data Centers ◽  
A New Technique ◽  
The Impact ◽  
Level Performance

This paper investigates the performance interference of blockchain services that run on cloud data centers. As the data centers offer shared computing resources to multiple services, the blockchain services can experience performance interference due to the co-located services. We explore the impact of the interference on Fabric performance and develop a new technique to offer performance isolation for Hyperledger Fabric, the most popular blockchain platform. First, we analyze the characteristics of the different components in Hyperledger Fabric and show that Fabric components have different impacts on the performance of Fabric. Then, we present QiOi, component-level performance isolation technique for Hyperledger Fabric. The key idea of QiOi is to dynamically control the CPU scheduling of Fabric components to cope with the performance interference. We implement QiOi as a user-level daemon and evaluate how QiOi mitigates the performance interference of Fabric. The evaluation results demonstrate that QiOi mitigates performance degradation of Fabric by 22% and improves Fabric latency by 2.5 times without sacrificing the performance of co-located services. In addition, we show that QiOi can support different ordering services and chaincodes with negligible overhead to Fabric performance.

237 Stable Performance with Reduced Antibiotic Use in Piglets Vaccinated with an E. coli F4/F18 Vaccine for the Prevention of F18-ETEC Post-weaning Diarrhea

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 139-140
Author(s):  
Frédéric A Vangroenweghe
Keyword(s):  
Antibiotic Use ◽  
Watery Diarrhea ◽  
Economic Losses ◽  
Standard Group ◽  
Performance Parameters ◽  
Oral Vaccination ◽  
E Coli ◽  
Technical Performance ◽  
Stable Performance ◽  
The Impact

Abstract Post-weaning Escherichia coli diarrhea (PWD) remains a major cause of economic losses for the pig industry. PWD, caused by enterotoxigenic E. coli (ETEC), typically provokes mild to severe watery diarrhea between 5–10 days after weaning. Recently, an oral live bivalent E. coli F4/F18 vaccine (Coliprotec® F4/F18; Elanco) was approved on the European market, which reduces the impact of PWD provoked by F4-ETEC and F18-ETEC. The objective was to compare technical results and antibiotic use following E. coli F4/F18 vaccination with previous standard therapeutic approach under field conditions. A 1600-sow farm (weaning at 26 days) with diagnosed problems of PWD due to F18-ETEC was selected. Piglets were vaccinated at 21 days with the oral live bivalent E. coli F4/F18 vaccine. At weaning, no standard group medication (ZnO and antibiotics) was applied for prevention of PWD. Several performance parameters were collected: treatment incidence (TI100), mortality and days in nursery. Statistical analysis was performed using JMP 14.0 – comparison of means. Oral E. coli F4/F18 vaccination significantly reduced TI100 (7 ± 2 days to 0 ± 1 days; P < 0.05). Mortality rate remained stable (2.05% in Control to 1.96% in Vaccinated group; P < 0.05). Days in nursery (40 ± 3 days) remained at the same level compared to pre-vaccination. The results show that live E. coli F4/F18 vaccination against PWD has led to similar technical performance parameters and mortality, in combination with a significant reduction in medication use. In conclusion, control of PWD through oral vaccination is a successful option in order to prevent piglets from the negative clinical outcomes of F18-ETEC infection during the post-weaning period.

Effect of Tensile Strain on Performance Parameters of Different Structures of MoS2 Monolayer

2021 ◽  
Author(s):  
Priya kaushal ◽  
Tarun Chaudhary ◽  
Gargi Khanna
Keyword(s):  
Tensile Strain ◽  
Computational Study ◽  
Level Structure ◽  
Charge Carriers ◽  
Performance Parameters ◽  
Mos2 Monolayer ◽  
Higher Temperature ◽  
Silicon Doped ◽  
The Impact ◽  
Biaxial Tensile Strain

Abstract The present work is based on the computational study of MoS2 monolayer and effect of tensile strain on its atomic level structure. The bandgap for MoS2 monolayer, defected MoS2 monolayer and Silicon-doped monolayer are 1.82 eV (direct bandgap), 0.04 (indirect bandgap) and 1.25eV (indirect bandgap), respectively. The impact of tensile strain (0-0.7%) on the bandgap and effective mass of charge carriers of these three MoS2 structure has been investigated. The bandgap decrease of 5.76%, 31.86% and 6.03% has been observed in the three structures for biaxial strain while the impact of uniaxial strain is quite low. The impact of higher temperature on the bandgap under biaxial tensile strain has been also analyzed in this paper. These observations are extremely important for 2D material-based research for electronic applications.

scholarly journals Improving End-of-Life Care: Palliative Care Embedded in an Oncology Clinic Specializing in Targeted and Immune-Based Therapies

2017 ◽  
Vol 13 (9) ◽  
pp. e729-e737 ◽  
Author(s):  
David J. Einstein ◽  
Susan DeSanto-Madeya ◽  
Matthew Gregas ◽  
Jessica Lynch ◽  
David F. McDermott ◽  
...  
Keyword(s):  
Palliative Care ◽  
Usual Care ◽  
End Of Life ◽  
Odds Ratio ◽  
Care Clinic ◽  
Usual Practice ◽  
Embedded Model ◽  
Enrollment Rates ◽  
Oncology Practice ◽  
The Impact

Purpose: Patients with advanced cancer benefit from early involvement of palliative care. The ideal method of palliative care integration remains to be determined, as does its effectiveness for patients treated with targeted and immune-based therapies. Materials and Methods: We studied the impact of an embedded palliative care team that saw patients in an academic oncology clinic specializing in targeted and immune-based therapies. Patients seen on a specific day accessed the embedded model, on the basis of automatic criteria; patients seen other days could be referred to a separate palliative care clinic (usual care). We abstracted data from the medical records of 114 patients who died during the 3 years after this model’s implementation. Results: Compared with usual care (n = 88), patients with access to the embedded model (n = 26) encountered palliative care as outpatients more often ( P = .003) and earlier (mean, 231 v 109 days before death; P < .001). Hospice enrollment rates were similar ( P = .303), but duration was doubled (mean, 57 v 25 days; P = .006), and enrollment > 7 days before death—a core Quality Oncology Practice Initiative metric—was higher in the embedded model (odds ratio, 5.60; P = .034). Place of death ( P = .505) and end-of-life chemotherapy (odds ratio, 0.361; P = .204) did not differ between the two arms. Conclusion: A model of embedded and automatically triggered palliative care among patients treated exclusively with targeted and immune-based therapies was associated with significant improvements in use and timing of palliative care and hospice, compared with usual practice.

Quantum Effects on the Performance of SOI Double-Gate Mosfet

2013 ◽  
Vol 685 ◽  
pp. 185-190
Author(s):  
Slimani Samia ◽  
Djellouli Bouaza
Keyword(s):  
Gate Dielectric ◽  
Quantum Effects ◽  
Double Gate ◽  
Performance Parameters ◽  
Tunnel Current ◽  
High Permittivity ◽  
High Drive ◽  
Double Gate Mosfet ◽  
The Impact ◽  
Current Drain

In spite of progress in silicon technology, the end of Mosfet scaling can be anticipated for the year 2015 so the introduction of high permittivity gate dielectric is the envisaged solution to reduce the current leakage that drives up power consumption. In this paper we investigate the impact of different gate length on SOI double gate MOSFET when SiO2 is replaced by ZrO2 as the gate dielectric using Nextnano Simulator. The impact of the quantum effects also observed on performance parameters of the DG-MOSFET such as on current, off current, drain induced barrier lowering, and sub-threshold. It is observed that less EOT with high permittivity reduces the tunnel current and serves to maintain high drive current.

Investigations on thermodynamic processes of a novel pneumatic drive asymmetric Gifford-McMahon cycle cryorefrigerator

2021 ◽  
pp. 1-21
Author(s):  
Debashis Panda ◽  
Suraj Kumar Behera ◽  
Ashok Kumar Satapathy ◽  
Sunil K. Sarangi
Keyword(s):  
Numerical Model ◽  
Performance Parameters ◽  
Pneumatic Drive ◽  
Governing Equations ◽  
Expansion Process ◽  
Intake Process ◽  
The Impact ◽  
First Time ◽  
Thermodynamic Processes ◽  
Dead Centre

Abstract In this paper, a numerical and experimental investigation is conducted on a novel pneumatic-drive asymmetric Gifford-McMahon cycle cryorefrigerator for the first time. In the pneumatic-drive asymmetric Gifford-McMahon cycle cryorefrigerator, the duration of the assistance space exhaust process is kept higher than that of the assistance space intake process. Therefore, the displacer moves faster at the lower dead centre and slower at the upper dead centre inside the expander cylinder, which makes the duration of expansion process longer. The numerical model solves the governing equations of the refrigerant and dynamics of free-floating displacer iteratively to illustrate the refrigeration mechanisms. Additionally, the model computes the performance parameters of the cryorefrigerator, like refrigerating capacity, and specific refrigerating capacity. By adopting the numerical model, the impact of the loitering time on the thermodynamic processes is elaborated. It is perceived that, both refrigerating capacity and specific refrigerating capacity reduces with an increase in the loitering time. The experimental cooling characteristics are studied for different values of discharge to suction pressure ratios of helium compressor.

scholarly journals Effect of irrigation machines on soil compaction

2014 ◽  
Vol 60 (Special Issue) ◽  
pp. S1-S8
Author(s):  
J. Jobbágy ◽  
P. Findura ◽  
F. Janík
Keyword(s):  
Soil Moisture ◽  
Soil Compaction ◽  
Field Measurements ◽  
Penetration Resistance ◽  
Technological Operation ◽  
Performance Parameters ◽  
Shallow Soil ◽  
Average Resistance ◽  
The Impact

The analysis of soil compaction with chassis of a wide-span irrigation machine Valmont was determined. The sprinkler had 12 two-wheeled chassis (size of tyre 14.9'' &times; 24''). During the evaluation of soil compaction, we monitored the values of penetration resistance and soil moisture during the operation of the sprinkler. Considering the performance parameters of the pump, the sprinkler was only half of its length (300 m) in the technological operation. In this area, also field measurements were performed in 19 monitoring points spaced both in tracks and outside the chassis tracks. The analysis showed the impact of compression with sprinkler wheels. The correction of obtained results of penetration resistance was applied in connection with soil moisture (mass) values according to Act No. 220/2004 (Lhotsk&yacute; et al. 1985). The results of average resistance ranged from 1.2 to 3.26 MPa. The values of the max. resistance ranged from 2.3 to 5.35 MPa. The results indicated a shallow soil compaction; however, it is not devastating.

Full Frontal Crashworthiness of Carbon Fiber Composite Front Bumper Crush Can (FBCC) Structures

2017 ◽  
Author(s):  
Y. Dixit ◽  
P. Begeman ◽  
G. S. Dhaliwal ◽  
G. Newaz ◽  
D. Board ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
High Speed ◽  
Fiber Composite ◽  
Video Tracking ◽  
Carbon Fiber Composite ◽  
Component Level ◽  
Frontal Crash ◽  
Impact Performance ◽  
Testing Method ◽  
The Impact

This research study highlights the testing method and relevant results for assessing impact performance of a carbon fiber composite front bumper crush can (FBCC) assembly subjected to full frontal crash loading. It becomes extremely important to study the behavior of lightweight composite components under a crash scenario in order to apply them to automotive structures to reduce the overall weight of the vehicle. Computer-aided engineering (CAE) models are extremely important tools to virtually validate the physical testing by assessing the performances of these structures. Due to lack of available studies on carbon fiber composite FBCCs assemblies under the frontal crash scenario, a new component-level test approach would provide assistance to CAE models and better correlation between results can be made. In this study, all the tests were performed by utilizing a sled-on-sled testing method. An extreme care was taken to ensure that there is no bottoming-out force for this type of test while adjusting the impact speed of sled. Full frontal tests on FBCC structures were conducted by utilizing five high-speed cameras (HSCs), several accelerometers and a load wall. Excellent correlation was achieved between video tracking and accelerometers results for time histories of displacement and velocity. The standard deviation and coefficient of variance for the energy absorbed were very low suggesting the repeatability of the full frontal tests. The impact histories of FBCC specimens were consistent and in excellent agreement with respect to each other. Post-impact photographs showed the consistent crushing of composite crush cans and breakage of the bumper beam from middle due to the production of tensile stresses stretched caused by straightening of the bumper curvature after hitting the load wall.

Performance Improvements of Random Dopant Fluctuation-Induced Variability in Negative Capacitance MOSFETS

2019 ◽  
Vol 19 (01) ◽  
pp. 2050002
Author(s):  
W. F. Lü ◽  
L. Dai ◽  
Z. F. Zhao ◽  
M. Lin
Keyword(s):  
Performance Improvement ◽  
Decisive Role ◽  
Feedback Mechanism ◽  
Negative Capacitance ◽  
Performance Parameters ◽  
Performance Improvements ◽  
Random Dopant Fluctuation ◽  
Statistical Variations ◽  
The Impact ◽  
Random Dopant

In this paper, we investigate the impact of random dopant fluctuation (RDF) on the statistical variations in negative capacitance MOSFETs (NCFETs) through a device simulation coupled with the Landau–Khalatnikov (LK) equation. Compact models for feedback mechanisms that are based on the internal gate voltage amplification in NCFETs are proposed. The results show that internal voltage amplification plays a decisive role in performance improvement of device variability. Further, our simulation study demonstrates that owing to the feedback mechanism, the dispersions of the performance parameters in NCFETs exhibit different statistical distribution characteristics compared to their MOSFET counterparts. Our study may provide further insight regarding device and/or circuit designs utilizing NCFETs.

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