bluuebunny/crossref_metadata_2025_split huggingface dataset:
Finite Element Model Based Full Spectrum Response Analysis of a Cracked Rotor With Internal and External Damping
Authors: Roy Dipendra Kumar , Tiwari Rajiv 
Published: January 2020

Abstract
The ratio of internal and external damping is one of the important fault parameters and it leads to instability of a rotor shaft at higher spin speeds. The crack in a rotor is one of the sources of its instability due to the crack internal damping. A rotor with crack internal damping that originates from the rubbing action between the two crack faces. For a sustained stable operation of the rotor, it is imperative to analyze rotor parameters such as the internal and external damping and other parameters, like the additive crack stiffness and disc eccentricity. Therefore, the present work considers a full spectrum response analysis of a transverse cracked shaft based on the finite element method. The rotary and translations of inertia are considered including of gyroscopic effect in the rotor system. The transverse crack is modeled based on the switching crack assumption. The crack in the rotor gives forcing with multiple harmonics with the forward and backward. The equation of motion has been developed for the rotor system having four degrees of freedom at each node and using MATLAB™ Simulink the responses are generated for a numerical example.
Fluid Thermal Network Studies on Cooled Nozzle Guide Vane
Authors: Kukutla Pol Reddy , Prasad B. V. S. S. S. 
Published: January 2020

Abstract
The aerothermal analysis is reported with the help of one-dimensional network modeling for the impingement cum film cooled gas turbine vane. The purpose of this one-dimensional simulation is to obtain the optimized film hole diameters of each row by analyzing the coolant flow distribution and overall effectiveness variations. FlownexR2017 commercial code is used to determine the detailed steady-state performance of the cooling vane. The results show that it is a useful simulation tool to obtain improved effectiveness of film cooling rows in a relatively short turn around time.
Performance Enhancement of a Hydraulic Savonius Turbine by Optimizing Overlap and Gap Ratios
Authors: Kerikous Emeel , Thévenin Dominique 
Published: January 2020

Abstract
Due to the significant increase in the human population, satisfying its energy demand becomes a major challenge at present and in the future. Hydropower is a form of renewable energy that converts the potential or kinetic energy of water to useful mechanical power. Considering the low speed of streaming water, hydraulic Savonius turbines can be effectively used for such conditions. Such turbines are robust and very simple to manufacture. However, Savonius turbines suffer from a poor efficiency. For this purpose, an optimization process was done to improve the power density of a hydraulic Savonius turbine while keeping its simple structure. Here in this study, the two main geometry parameters, i.e., 1) the overlap ratio, 2) the gap ratio, are served. Furthermore, the optimal operating range for both parameters is presented. To achieve this goal, many different geometries of the turbine are simulated by using the computational fluid dynamics (CFD) code Star-CCM+. In the optimization process, all simulations are driven by the in-house software OPAL++. The output power coefficient (Cp) is considered as a single target function to be maximized. The performance of the optimal geometry is compared with the standard design over the whole range of operation, leading to an improvement in the performance of the turbine by about 8%.
Simulation of Pollutant Emissions in a Small-Sized Combustion Chamber With a Gas Fuel for Various Regime Modes
Authors: Gurakov Nikita I. , Zubrilin Ivan A. , Chechet Ivan V. , Anisimov Vladislav M. , Matveev Sergey S. , Idrisov Dmitry V. , Anisimov Michail Y. 
Published: January 2020

Abstract
The study shows the results of the emission simulation in a small-sized combustion chamber. The influence of temperature and equivalence ratio on CO and CxHy in the combustion chamber was investigated. Experiments and calculations were carried out for the following modes: temperature at the inlet of the combustion chamber Tinlet = 323 ... 523 K; equivalence ratio φ = 0.2 ... 0.33; normalized flow rate at the inlet of the combustion chamber λ = 0.1 ... 0.3. The simulation of combustion of natural gas was carried out.
The studies were conducted using CFD software and experimental methods. Measurements of the combustion products composition were carried out by the method of sampling collection and subsequent chromatographic analysis. The flow and combustion processes were simulated in a three-dimensional steady formulation using the Reynolds-averaged Novier-Stokes equations (RANS) and in a transient formulation using the Large Eddy Simulation (LES) method. The combustion processes were simulated by Flamelet Generated Manifold model in conjunction with the probability density function method (PDF). In addition to the above methods, the method of the reactor network model (RNM) was used to simulate the emission. As a result, a comparison of the calculated and experimental data of concentrations values of combustion products and emissions indices averaged over the combustion chamber outlet was conducted. According to the results of the calculated-experimental study obtained: - the simulated concentrations values of the main combustion products such as CO2 and H2O qualitatively and quantitatively coincide with the experimental data (the discrepancy is less than 5%) for all three approaches — RANS, LES, RNM; - when modeling CO emissions, the discrepancy between the calculated emission indices obtained by the RANS and LES methods is greatly underestimated relative to the experimental data, whereas the values calculated by the RNM method deviate from the experiment by less than 10%; - mass concentration values of unburned hydrocarbons obtained by the RANS method are overestimated relative to the experimental values, while using the LES with RNM methods, the discrepancy does not exceed 10%.
A Comparative Study of Scroll Expander Performance Using CO2 and Zeotropic Mixtures As Working Fluids
Authors: Narasimhan Arun Kumar , Guillen Perez Diego , Goswami D. Yogi 
Published: January 2020

Abstract
Scroll expanders are generally used for low temperature power generation applications due to their inherently small built-in volume ratio. The working fluid and operating conditions play an important role in the expander performance as well as its physical size and volume ratio. Hence, a comparative study of scroll expander performance was carried out between two different working fluids, R433C and supercritical (s-CO2). The s-CO2 Brayton cycle achieved a maximum cycle efficiency of 13.6% at an expander supply pressure of 11 MPa. Two separate scroll geometries were modeled for supercritical Organic Rankine Cycle (SORC) using R433C and s-CO2 Brayton cycle for the operating conditions that provided the maximum cycle performance. The s-CO2 scroll geometry achieved a maximum expander efficiency of 80% with a volume ratio of 2.5 and a diameter of 19 cm. The high inlet temperatures required a much higher volume ratio of 6.2 and scroll diameter of 30 cm for the R433C based SORC leading to greater leakages and lower expander efficiency of 62%. The comparative study shows that s-CO2 is better suited for scroll expander than R433C at such high expander supply temperatures.
Experimental Investigation of Droplet Velocity Fields From Elliptic Injectors in Subsonic Cross Flow
Authors: Uzair Alvi Ather , Thakur Amit , Jangam Srinivas , Kumar P. Pratheesh , Iyengar Venkat S. 
Published: January 2020

Abstract
The flow field associated with a liquid jet injected transversely into a crossflow, also referred as transverse jet has numerous applications in industrial, environmental and natural systems. Examples of these applications include air-breathing engines (gas turbine afterburners, ramjet and scramjet combustors), rocket engines, environmental control systems and natural flows. Earliest research of a jet in a crossflow has been motivated by applications related to environmental problems such as plume dispersal from exhaust or pipe stacks or liquid effluent dispersal in streams. This method of liquid fuel/air mixture preparation enhances flame stabilization, fuel conversion efficiency, and reduction in emissions. In gas turbine applications because of the very limited residence time available for effective fuel air mixing, detailed investigations into spray characteristics of different injector configurations in a crossflow environment is desirable for identifying promising configurations with measurements in the near field to acquire reliable spray data for development of CFD models. The velocity field of a liquid jet in the near field ejecting out from an elliptic injector into a crossflow of air were investigated experimentally at conditions relevant to gas turbine applications. A rig was set up to investigate the injection of liquid jet in subsonic cross flow with a rectangular test section of cross section measuring 100 mm by 140 mm. Experiments were done with a two injector configurations a circular 0.8mm diameter plain orifice injector and a elliptic injector with an equivalent effective area of 0.7 mm (minor axis) by 0.95 mm (major axis) which was flush mounted on the bottom plate of test section. PIV technique was used to measure droplet velocity field and distributions in the near field of the spray. Measurements were performed at a distance of 5 mm from the bottom wall in the span wise plane and the results were compared with a circular injector. It was seen that no significant differences were observed in the u and v velocity components for the elliptic and circular injectors where the geometry changes are small suggesting that parameters like velocity are not significantly affected by small changes in injector exit geometry. Further for elliptic jets it was observed that increasing the crossflow velocity and maintaining the same liquid flow rate lead to an increase in the lateral spread of the spray with no significant change in the mean vorticity values.
Dynamic Analysis of End Conditions for Shell Side Pipings of STHE
Authors: Pagar Nitin D. , Gawande S. H. 
Published: January 2020

Abstract
Shell and tube heat exchangers [STHE] play a very vital role in energy conversion systems, process industries like chemical, pharmaceutical, refineries etc. and in different power plants. For designing shell and tube heat exchangers, the tubes vibrational response (internally) to any random excitations of fluid flow need to be understandable. Also, circumferential inlet pipe or tube at the entrance region of the shell side, generally subject to the fluid thrust in the bends of typical pipe arrangements. It produces loadings forces and moments, leading to unavoidable vibrations. The goal of vibration analysis is to ensure that fatigue damage or fretting wear does not occur, as well as, predicted frequencies, amplitudes shall be within acceptable limits criteria. This paper reports the vibration analysis of different piping arrangement of different end conditions to understand its effects on frequencies and modes so that a designer must mitigate it, at the initial stage. Axial, lateral and torsional vibrations are analyzed for different end conditions. The boundary conditions used are both ends fixed, one end fixed and other end free, both ends free and one end fixed-other end attached to a weight. Analytical procedure is carried out to determine the frequencies for axial, lateral and torsional cases. FEA analysis and experiment using an FFT analyzer is carried out to check the convergence of the results. Very useful results are established which generates the philosophy to protect the pipings from the resonant frequencies subjected to different end conditions.
Feasibility of an Offshore Wind Farm in the North Sea Region
Authors: Pichitkul Auraluck , Sankar Lakshmi N. , Jagoda Jechiel 
Published: January 2020

Abstract
Preliminary design and feasibility investigation of a 2-MW wind turbine for offshore wind farm operation are presented in this study. A region in the North Sea, to the west of the West Frisian Islands offshore of Dutch coast is selected as a potential wind farm site due to its high availability of wind resources. Based on the wind data of the selected site and operating requirements of the wind farm, preliminary sizing and conceptual design of wind turbine rotor blades are carried out. Performance of the rotor design is first assessed by classical blade element-momentum theory, followed by state-of-the-art commercial CFD software. Economics and feasibility analysis of this wind turbine operating in an offshore wind farm setting is conducted using DOE/NREL scaling cost model. The feasibility investigation results reveal that the cost of energy (COE) for operating the current wind turbine design at the selected wind farm site is considerably lower than the average COE in the Netherlands, indicating high potential of commercially making profits. Environmental impact studies have also been done.
PD-L1 expression is an unfavourable prognostic indicator in Asian renal cell carcinomas
Authors: Yeong Joe , Zhao Zitong , Lim Jeffrey Chun Tatt , Li Huihua , Thike Aye Aye , Koh Valerie Cui Yun , Teh Bin Tean , Kanesvaran Ravindran , Toh Chee Keong , Tan Puay Hoon , Khor Li Yan 
Published: January 2020

Background/aimsThe programmed cell death receptor 1 (PD-1) checkpoint inhibitor, nivolumab, has been approved for the treatment of metastatic renal cell carcinoma (RCC). However, the understanding of the expression and distribution of PD ligand 1 (PD-L1) in the tumour immune microenvironment and its prognostic role in an Asian cohort is limited. Our group investigated PD-L1 protein expression in a cohort of Asian patients with RCC of mixed ethnicity, using two commercially available antibody clones.MethodsE1L3N and SP263 anti-PD-L1 clones were used to categorise RCCs of various histological subtypes, diagnosed at our institution between 1995 and 2008, into PD-L1-positive or PD-L1-negative groups, based on a 1% Tumour Proportion Score (TPS) cut-off.ResultsIn total, 267 (83%) clear cell (cc)RCC and 55 (17%) non-ccRCC cases were studied. Overall PD-L1 protein expression rates for the entire cohort were 13% and 8% for the E1L3N and SP263 clones, respectively. Patients bearing PD-L1-positive tumours experienced significantly decreased disease-free survival (DFS; E1L3N: p=0.01; SP263: p=0.03) but not overall survival, compared with those with PD-L1-negative tumours. Multivariate survival analysis further confirmed the results of the E1L3N clone (HR 1.85, 95% CI 1.10 to 3.13, p=0.02), but not SP263, after adjusting for pathological stage, histological subtype and grade. The addition of PD-L1 (E1L3N) TPS to clinicopathological features significantly increased the prognostic value for DFS (∆LRχ2=5.25; p=0.022), compared with clinicopathological features alone.ConclusionsPD-L1 protein expression was associated with an unfavourable prognosis in our study cohort. PD-L1 (E1L3N) expression was an independent prognostic indicator of clinical outcome in all RCCs when using a 1% cut-off.
Weak decays of triply heavy tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$
Authors: Xing Ye 
Published: January 2020

AbstractWe study masses, lifetimes and weak decays of the triply heavy tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯. The masses of tetraquark are explored under two different models. Further more, our calculations show a possibility of existence for the stable triply heavy tetraquark $$b{\bar{c}} b{\bar{q}} $$bc¯bq¯ with $$J^P=1^+$$JP=1+ which should be verified in experiment. Following the heavy quark expanding(HQE), the lifetimes of tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ can be expressed as the summation of different dimension operators. Particularly, we obtain the lifetimes of $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ at the next-to-leading order(NLO) given as $$\tau (T^{\{bb\}}_{\{{\bar{c}}{\bar{q}}\}})=0.70\times 10^{-12}s$$τ(T{c¯q¯}{bb})=0.70×10-12s. Besides, we construct the weak decays Hamiltonian of $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ in hadronic level under the SU(3) flavor symmetry. The discussion of the Hamiltonian can deduce the decay amplitudes and width relations of the tetraquarks. Following the choosing rules, we collect some golden channels for the mesonic decays of tetraquarks, which will be helpful to search for triply heavy tetraquarks $${b{\bar{c}}}{b{\bar{q}}}$$bc¯bq¯ in future experiments.
Improved Sleep Quality Improves Blood Pressure Control among Patients with Chronic Kidney Disease: A Pilot Study
Authors: Ali Waleed , Gao Guimin , Bakris George L. 
Published: January 2020

<b><i>Background:</i></b> Despite the abundance of data documenting the consequences of poor sleep quality on blood pressure (BP), no previous study to our knowledge has addressed the impact of sleep improvement on resistant hypertension among patients with chronic kidney disease (CKD). <b><i>Methods:</i></b> The aim of this pilot study was to determine whether improved sleep quality and duration will improve BP control in patients with resistant hypertension and CKD. It was a prospective single-center cohort study that involved 30 hypertensive subjects with CKD presenting with primary resistant hypertension and poor sleep quality or duration &#x3c;6 h/night. Sleep quality and duration were modified using either sleep hygiene education alone or adding sleep medication. The cohort’s BP was followed every 3 months for 6-month duration. The average home and clinic BPs were collected at each follow-up visit. The primary outcome baseline change in systolic BP (SBP) and diastolic BP (DBP; home and clinic) at 3 and 6 months after documented sleep improvement. Secondary outcomes included change from baseline in mean arterial pressure, and delta SBP after sleep improvement. <b><i>Results:</i></b> African American patients represented 50% of the cohort. All patients had evidence of CKD with GFR ≤60 mL/min and were obese with 40% having type 2 diabetes mellitus. The primary endpoint of change in clinic SBP and DBP was significantly reduced at 3 months, baseline 156 ± 15/88 ± 8 vs. 3 months 125 ± 14/73 ± 7 (<i>p</i> &#x3c; 0.0001). This difference persisted at 6 months. However, there was no further reduction in-home or clinic BPs between the 3- and 6-month periods. Home and clinic average delta SBP change at 3 months from baseline was –34.4 ± 15 and –30.8 ± 19 mm Hg respectively. Delta SBP change was associated with sleep improvement of &#x3e;6 h/night, that is, gaining an extra 3–4 h’ sleep duration, home; <i>R</i><sup>2</sup> = 0.66, <i>p</i> &#x3c; 0.0001 and clinic; <i>R</i><sup>2</sup> = 0.49, <i>p</i> &#x3c; 0.0001. <b><i>Conclusion:</i></b> Optimizing sleep quality and duration to &#x3e;6 h/night improved BP control and was associated with a significant delta change in SBP within 3 months of follow-up. Physicians should obtain a sleep history in patients with CKD who present with resistant hypertension.
Estimating Myocardial Infarction Size With a Simple Electrocardiographic Marker Score
Authors: Lee Daniel C. , Albert Christine M. , Narula Dhiraj , Kadish Alan H. , Panicker Gopi Krishna , Wu Edwin , Schaechter Andi , Pester Julie , Chatterjee Neal A. , Cook Nancy R. , Goldberger Jeffrey J. 
Published: January 2020

Background

Myocardial infarction (
MI
) size is a key predictor of prognosis in post‐
MI
patients. Cardiovascular magnetic resonance (
CMR
) is the gold standard test for
MI
quantification, but the
ECG
is less expensive and more widely available. We sought to quantify the relationship between
ECG
markers and cardiovascular magnetic resonance infarct size.

Methods and Results

Patients with prior
MI
enrolled in the
DETERMINE
(Defibrillators to Reduce Risk by Magnetic Resonance Imaging Evaluation) and PRE‐DETERMINE Trial and Registry were included.
ECG
leads were analyzed for markers of
MI
: Q waves, fragmented
QRS
, and T wave inversion.
DETERMINE
Score=number of leads with [Q waves×2]+[fragmented
QRS
]+[T wave inversion]. Left ventricular ejection fraction (
LVEF
) and infarct size as a percentage of left ventricular mass (
MI
%) were quantified by cardiovascular magnetic resonance. The Modified Selvester Score estimates
MI
size from 37
ECG
criteria. In 551 patients (aged 62.1±10.9 years, 79% men, and
LVEF
=40.3±11.0%),
MI
% increased as the number of
ECG
markers increased (
P
<0.001). By univariable linear regression, the
DETERMINE
Score (range 0–26) estimated
MI
% (
R
2
=0.18,
P
<0.001) with an accuracy approaching that of
LVEF
(
R
2
=0.22,
P
<0.001) and higher than the Modified Selvester Score (
R
2
=0.09,
P
<0.001). By multivariable linear regression, addition of the
DETERMINE
Score improved estimation of
MI
% over
LVEF
alone (
P
<0.001) and over Modified Selvester Score alone (
P
<0.001).

Conclusions

In patients with prior
MI
, a simple
ECG
score estimates infarct size and improves infarct size estimation over
LVEF
alone. Because infarct size is a powerful prognostic indicator, the
DETERMINE
Score holds promise as a simple and inexpensive risk assessment tool.
Ethnic Diversity and Growth: Revisiting the Evidence
Authors: Montalvo José G. , Reynal-Querol Marta 
Published: January 2020

Abstract
The relationship between ethnic heterogeneity and economic growth is complex. Empirical research working with cross-country data finds a negative, or statistically insignificant, relationship. However, analysis at the city level finds a positive effect of diversity on wages and productivity. Generally there is a trade-off between the economic benefits of diversity and the costs of heterogeneity. Using cells of fixed size, we find that the relationship between diversity and growth is positive for small geographical areas. In the case of Africa, we argue that the explanation is the increase in trade at the boundaries between ethnic groups due to ethnic specialization.
Accountability, Political Capture, and Selection Into Politics: Evidence from Peruvian Municipalities
Authors: Artiles Miriam , Kleine-Rueschkamp Lukas , León-Ciliotta Gianmarco 
Published: January 2020

Abstract
We estimate the effects of political accountability on the selection of politicians when accountability mechanisms are prone to political capture. We compare the characteristics of candidates running in municipalities where the previous incumbent was ousted from office through a recall referendum with those who run where the recall referendum failed by a small margin. Having a recalled incumbent in the previous term causes a negative selection of candidates in terms of their education and previous experience. They are also less representative of indigenous groups. The results are driven by localities where the accountability institution is likely used for political purposes.
Living without a Soul: Why God and the Heavenly Movers Fall Outside of Aristotle’s Psychology
Authors: Cohoe Caleb 
Published: January 2020

Abstract
I argue that the science of the soul only covers sublunary living things. Aristotle cannot properly ascribe ψυχή to unmoved movers since they do not have any capacities that are distinct from their activities or any matter to be structured. Heavenly bodies do not have souls in the way that mortal living things do, because their matter is not subject to alteration or generation. These beings do not fit into the hierarchy of soul powers that Aristotle relies on to provide unity to ψυχή. Their living consists in their activities, not in having a capacity for activity.