bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparative Study on N-Dot Acceleration Technique
Authors: Yang Shubo , Wang Xi 
Published: September 2016

For aero-engines, the throttle command is often changed dramatically, which will perturb the control error (defined as actual rotor speed minus desired rotor speed) of the primary set-point controller. When the perturbation is amplified by the gain, the controller will output unreasonable values of control variables, i.e. the mass of fuel flow, and cause abnormal engine operation. For this reason, limit protection controllers are applied to constrain the controlled variables at a safe level. Besides, the transient control modes are required to provide smooth, stall free operation of the engine.
The schedule-based approach, which is the traditional transient control mode, is easy to implement but the performance of acceleration and deceleration will suffer from degradation or manufacturing errors. With the development of digital control system, N-dot control mode has been adopted in some modern aero-engines, which focuses on rotor acceleration rather than rotor speed. To some extent, this method can overcome the obstacles of the schedule-based approach.
In terms of N-dot control mode, there are two main methods: direct control and indirect control. The former one suggests using a differentiator to get the actual N-dot value, then minus it by the desired N-dot value to get the error of N-dot. When the error is reduced to zero by a controller, the actual N-dot value follows the desired N-dot value. The latter one suggests inputting the desired N-dot value to an integrator for a rotor speed value, which essentially transforms the N-dot command to the speed command. With this transformation, the familiar set-point controller can be used to control the engine following the N-dot command indirectly.
This paper presents implementation schemes of the two types of N-dot control, and focuses on a comparative study of them. To avoid integral windup issue when the indirect method switches controllers, such as from N-dot controller to set-point controller, we have introduced a logic to determine whether the integrator is operational. This design allows flexible switchings.
After frequency domain analysis, we find out that the essential difference between the two schemes lies in the magnitude of crossing frequency. The direct N-dot control, with a higher crossing frequency, has faster responses but is sensitive to noise. While the indirect N-dot control, with a lower crossing frequency, has slower responses but can suppress noise. When the dynamic nature of sensor and actuator is considered, the direct N-dot control with a higher crossing frequency may cause the close-loop system unstable.
Using a reliable aero-engine mathematical model, we designed a set of simulations to test the two N-dot schemes. The simulation results showed that the direct N-dot control performed better than the indirect one under ideal situation. When noise or dynamic nature of sensor and actuator was taken into consideration, however, the indirect N-dot control was more robust, which confirmed the analysis above.
A Study on the Emissions of Alternative Aviation Fuels
Authors: Riebl Sebastian , Braun-Unkhoff Marina , Riedel Uwe 
Published: September 2016

Currently, the aviation sector is seeking for alternatives to kerosene from crude oil, as part of the efforts combating climate change by reducing greenhouse gas (GHG) emissions, in particular carbon dioxide (CO2), and ensuring security of supply at affordable prices.
Several synthetic jet fuels have been developed including sustainable bio-kerosene, a low-carbon fuel. Over the last years, the technical feasibility as well as the compatibility of alternative jet fuels with today’s planes has been proven However, when burning a jet fuel, the exhaust gases are a mixture of many species, going beyond CO2 and water (H2O) emissions, with nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbons (UHC) including aromatic species and further precursors of particles and soot among them. These emissions have an impact on the local air quality as well as on the climate (particles, soot, contrails). Therefore, a detailed knowledge and understanding of the emission patterns when burning synthetic aviation fuels is inevitable.
In the present paper, these issues are addressed by studying numerically the combustion of four synthetic jet fuels (Fischer-Tropsch fuels). For reference, two types of crude-oil based kerosenes (Jet A-1 and Jet A) are considered, too. Plug flow calculations were performed by using a detailed chemical-kinetic model validated previously. The composition of the multi-component jet fuels were imaged by using the surrogate approach. Calculations were done for relevant temperatures, pressures, residence times, and fuel equivalence ratios φ.
Results are discussed for NOx, CO as well as benzene and acetylene as major soot precursors. According to the predictions, the NOx and CO emissions are within about ± 10% for all fuels considered, within the parameter range studied: T = 1800 K, T = 2200 K; 0.25 ≤ φ ≤ 1.8; p = 40 bar; t = 3 ms. The aromatics free GtL (Gas to Liquid) fuel displayed higher NOx values compared to Jet A-1/A. In addition, synthetic fuels show slightly lower (better) CO emission data than Jet A-1/A. The antagonist role of CO and NOx is apparent. Major differences were predicted for benzene emissions, depending strongly on the aromatics content in the specific fuel, with lower levels predicted for the synthetic aviation fuels. Acetylene levels show a similar, but less pronounced, effect.
Analysis of High Pressure Turbine Nozzle Guide Vanes Considering Geometric Variations
Authors: Högner Lars , Nasuf Alkin , Voigt Paul , Voigt Matthias , Vogeler Konrad , Meyer Marcus , Berridge Christopher , Goenaga Frederic 
Published: September 2016

Geometric variations caused by manufacturing scatter can influence the aerodynamic performance of turbomachinery components. In case of nozzle guide vanes (NGVs), the capacity is of particular importance due to its influence on the entire engine behaviour, since often the narrowest cross section of the turbine, which limits the capacity, is found in the first NGV stage.
Within this scope, the present paper illustrates different methods in order to quantify the impact of geometric variations of high pressure turbine (HPT) NGVs with respect to capacity change during the development process. At first, in the design phase, a parametric CAD model of the NGV can be used to perform an initial assessment of the effect caused by different geometric variations onto capacity. The results of this study can for example be used to set the tolerances for the subsequent manufacturing process.
As soon as the first real hardware components become available, their geometry can nowadays be accurately captured using optical measurement techniques. Consequently, reverse engineering (RE) methods can be used to enable numerical assessment of geometric variability since manufacturing scatter is determined and incorporated into the subsequent CFD analysis. The process to perform this assessment is described in the second part of the paper and its results are compared to the initial CAD-based study. The investigation is conducted using an example of a state-of-the-art NGV stage provided by Rolls-Royce.
Model Based Diagnostics of AE-T100 Micro Gas Turbine
Authors: Mahmood Mariam , Martini Alessio , Traverso Alberto , Bianchi Enrico 
Published: September 2016

The growing environmental impacts and dwindling supply of conventional fuels have led to the development of more efficient and clean energy systems. Micro gas turbines (mGT) have emerged as energy conversion technology, which offer promising features like high fuel flexibility, low emissions level, and efficient cogeneration of heat and power (CHP). Numerical simulation is a vital tool to predict the off-design performance of mGT cycles, and it also helps in cycle optimization. Starting from a model available at Ansaldo Energia, for steady state simulation of mGT T100 cycles based on user requirements, within the cooperation between University of Genova (Unige) and Ansaldo Energia, a new more comprehensive simulation tool has been developed through the incorporation of additional components, features, and involving a more detailed mathematical approach. The most important upgrades involved a number of different air path flows and the power electronics, which takes into account the power consumption from auxiliary components as well as the generator and inverter efficiencies.
Once the model has been verified against the existing tools, it was used in real operating conditions at the Ansaldo Energia test rig. The mGT performance has been assessed for different power levels, starting from 100 kW (nominal power) to 60 kW and then back to 100 kW, with 10 kW steps. The two tests at 100 kW operating conditions have been carried out with two different ambient temperatures: 20°C and 25°C, respectively. Data have been acquired under stable operating conditions, considering the recuperator cold outlet temperature as the stability indicator.
Finally the new model AE-T100 has been used also for diagnosis of the whole mGT cycle. The model has been successfully applied to a special mGT equipped with an on-purpose damaged recuperator, identifying the causes of performance degradation.
Numerical and Experimental Investigation of Heat Transfer in a Low Flow Single Stage Centrifugal Compressor
Authors: Cui Michael , Hohlweg William 
Published: September 2016

Heat transfer is an integral part of centrifugal compressor working process. The heat transfer can be generated by compressed gas (internal heating) or external heat sources (external heating). The heat transfer affects compressor performance directly through two mechanisms: dissipate impeller shaft power to heat to generate thermal losses; add extra thermal energy (enthalpy) to working fluid to distort stage performance value. The impacts of both these mechanisms are inversely proportional to the flow coefficient of the compressor. To optimize the compressor design and to evaluate their performance accurately, the physical mechanisms that control thermal fluid flow and heat transfer inside centrifugal compressors need to be studied.
The current work investigates both internal and external heat transfer inside a single stage centrifugal compressor with low design flow coefficient. An integrated conjugate heat transfer (CHT) model of the compressor stage includes both the solid parts (impeller, guide vanes, and stationary walls) and the test gas. The heat transfer processes between the solid and fluid surfaces were quantified using the ANSYS CFX software. The stage studied was tested in a closed loop arrangement with both nitrogen and R134a gases over a range of speeds from choke to surge flow. The gas temperatures and pressures were measured throughout the flow path from inlet flange to discharge. The temperatures of the solid components were obtained for the regions with large temperature gradients. The concept of thermal losses is introduced to characterize the dissipation of the shaft work to heat. The fundamental physical mechanisms of thermal fluid flow inside the compressor are defined and the influence of heat transfer on the centrifugal compressor stage performance is quantified.
Complete Genome Sequence of Feline Calicivirus Strain GX01-2013 Isolated from Household Cats in Guangxi, Southern China
Authors: He Ping , Zhou Huabo , Zhao Weifeng , He Jianqiao , Li Ruikai , Ding Yangbao , Chen Quanjiang , Liu Lin , Wei Zuzhang , Huang Weijian , Chen Ying 
Published: September 2016

ABSTRACT
Here, we report the complete genome of a feline calicivirus (FCV) originating from household cats in Guangxi, southern China, in September 2013. To understand its genetic characteristics, we isolated FCV strain GX01-2013 from MDCK cells and determined its complete genome sequence.
Identification and Whole-Genome Sequencing of Four Enterovirus D68 Strains in Southern China in Late 2015
Authors: Chen Long , Shi Lei , Yang Hong , Gu Da-Yong , Meng Jun , Xu Yun-Qing , Yao Xiang-Jie , Zhang Hai-Long , Cheng Jin-Quan , Ma Han-Wu , Zhang Ren-Li , He Ya-Qing 
Published: September 2016

ABSTRACT
Four enterovirus D68 (EV-D68) strains from four children with influenza-like illness were identified in Shenzhen, southern China, in late 2015. Here, we announce the availability of these viral genomes in GenBank. The genomic sequences of these EV-D68 strains showed the closest phylogenetic relationship to strains from northern China.
Complete Genome Sequence of the Intracellular Bacterial Symbiont TC1 in the Anaerobic Ciliate
Trimyema compressum
Authors: Shinzato Naoya , Aoyama Hiroaki , Saitoh Seikoh , Nikoh Naruo , Nakano Kazuma , Shimoji Makiko , Shinzato Misuzu , Satou Kazuhito , Teruya Kuniko , Hirano Takashi , Yamada Takanori , Nobu Masaru K. , Tamaki Hideyuki , Shirai Yumi , Park Sanghwa , Narihiro Takashi , Liu Wen-Tso , Kamagata Yoichi 
Published: September 2016

ABSTRACT

A free-living ciliate,
Trimyema compressum
, found in anoxic freshwater environments harbors methanogenic archaea and a bacterial symbiont named TC1 in its cytoplasm. Here, we report the complete genome sequence of the TC1 symbiont, consisting of a 1.59-Mb chromosome and a 35.8-kb plasmid, which was determined using the PacBio RSII sequencer.
Impact of the Nordic hamstring and hip extension exercises on hamstring architecture and morphology: implications for injury prevention
Authors: Bourne Matthew N , Duhig Steven J , Timmins Ryan G , Williams Morgan D , Opar David A , Al Najjar Aiman , Kerr Graham K , Shield Anthony J 
Published: September 2016

BackgroundThe architectural and morphological adaptations of the hamstrings in response to training with different exercises have not been explored.PurposeTo evaluate changes in biceps femoris long head (BFLH) fascicle length and hamstring muscle size following 10-weeks of Nordic hamstring exercise (NHE) or hip extension (HE) training.Methods30 recreationally active male athletes (age, 22.0±3.6 years; height, 180.4±7 cm; weight, 80.8±11.1 kg) were allocated to 1 of 3 groups: (1) HE training (n=10), NHE training (n=10), or no training (control, CON) (n=10). BFLHfascicle length was assessed before, during (Week 5) and after the intervention with a two-dimensional ultrasound. Hamstring muscle size was determined before and after training via MRI.ResultsCompared withbaseline, BFLHfascicles were lengthened in the NHE and HE groups atmid-training(d=1.12–1.39, p<0.001) andpost-training(d=1.77–2.17, p<0.001) and these changes did not differ significantly between exercises (d=0.49–0.80, p=0.279–0.976). BFLHvolume increased more for the HE than the NHE (d=1.03, p=0.037) and CON (d=2.24, p<0.001) groups. Compared with the CON group, both exercises induced significant increases in semitendinosus volume (d=2.16–2.50, ≤0.002) and these increases were not significantly different (d=0.69, p=0.239).ConclusionNHE and HE training both stimulate significant increases in BFLHfascicle length; however, HE training may be more effective for promoting hypertrophy in the BFLH.
Effective psychological and psychosocial approaches to reduce repetition of self-harm: a systematic review, meta-analysis and meta-regression
Authors: Hetrick Sarah E , Robinson Jo , Spittal Matthew J , Carter Greg 
Published: September 2016

ObjectiveTo examine the efficacy of psychological and psychosocial interventions for reductions in repeated self-harm.DesignWe conducted a systematic review, meta-analysis and meta-regression to examine the efficacy of psychological and psychosocial interventions to reduce repeat self-harm in adults. We included a sensitivity analysis of studies with a low risk of bias for the meta-analysis. For the meta-regression, we examined whether the type, intensity (primary analyses) and other components of intervention or methodology (secondary analyses) modified the overall intervention effect.Data sourcesA comprehensive search of MEDLINE, PsycInfo and EMBASE (from 1999 to June 2016) was performed.Eligibility criteria for selecting studiesRandomised controlled trials of psychological and psychosocial interventions for adult self-harm patients.ResultsForty-five trials were included with data available from 36 (7354 participants) for the primary analysis. Meta-analysis showed a significant benefit of all psychological and psychosocial interventions combined (risk ratio 0.84; 95% CI 0.74 to 0.96; number needed to treat=33); however, sensitivity analyses showed that this benefit was non-significant when restricted to a limited number of high-quality studies. Meta-regression showed that the type of intervention did not modify the treatment effects.ConclusionsConsideration of a psychological or psychosocial intervention over and above treatment as usual is worthwhile; with the public health benefits of ensuring that this practice is widely adopted potentially worth the investment. However, the specific type and nature of the intervention that should be delivered is not yet clear. Cognitive–behavioural therapy or interventions with an interpersonal focus and targeted on the precipitants to self-harm may be the best candidates on the current evidence. Further research is required.
25-year trends in gender disparity for obesity and overweight by using WHO and IOTF definitions among Chinese school-aged children: a multiple cross-sectional study
Authors: Song Yi , Wang Hai-Jun , Dong Bin , Ma Jun , Wang Zhiqiang , Agardh Anette 
Published: September 2016

ObjectivesWe sought to explore 25-year trends of gender disparity in the prevalence of obesity and overweight both in urban and rural areas among Chinese children from 1985 to 2010.MethodsData included 1 280 239 children aged 7–18 years enrolled in the Chinese National Survey on Students's Constitution and Health (CNSSCH), which is the largest nationally representative sample of school-aged children in China. Obesity and overweight were defined according to both WHO and the International Obesity Task Force (IOTF) definitions. Logistic regression was used to estimate the prevalence OR (POR) of gender for obesity and overweight prevalence in different surveys.ResultsThe prevalence of obesity increased (WHO definition: from 0.10% to 4.3%; IOTF definition: from 0.03% to 2.2%) over the past 25 years in urban and rural areas among Chinese children and it was much higher among boys than girls at each survey point (p<0.01). The increasing trend was significant in all age subgroups (p<0.01). Although the prevalence of obesity continuously increased in boys and girls, the changing pace was more rapid in boys than in girls. PORs of boys versus girls for obesity also increased over time, and the estimates of PORs were higher in urban areas than in rural areas at each survey point.ConclusionsThe gradually increasing gender disparity in urban and rural areas suggests that the prevalence of obesity and overweight in boys, and especially in urban boys, contributes to a large and growing proportion of obese and overweight children.
Prescriber preferences for behavioural economics interventions to improve treatment of acute respiratory infections: a discrete choice experiment
Authors: Gong Cynthia L , Hay Joel W , Meeker Daniella , Doctor Jason N 
Published: September 2016

ObjectiveTo elicit prescribers' preferences for behavioural economics interventions designed to reduce inappropriate antibiotic prescribing, and compare these to actual behaviour.DesignDiscrete choice experiment (DCE).Setting47 primary care centres in Boston and Los Angeles.Participants234 primary care providers, with an average 20 years of practice.Main outcomes and measuresResults of a behavioural economic intervention trial were compared to prescribers' stated preferences for the same interventions relative to monetary and time rewards for improved prescribing outcomes. In the randomised controlled trial (RCT) component, the 3 computerised prescription order entry-triggered interventions studied included: Suggested Alternatives (SA), an alert that populated non-antibiotic treatment options if an inappropriate antibiotic was prescribed; Accountable Justifications (JA), which prompted the prescriber to enter a justification for an inappropriately prescribed antibiotic that would then be documented in the patient's chart; and Peer Comparison (PC), an email periodically sent to each prescriber comparing his/her antibiotic prescribing rate with those who had the lowest rates of inappropriate antibiotic prescribing. A DCE study component was administered to determine whether prescribers felt SA, JA, PC, pay-for-performance or additional clinic time would most effectively reduce their inappropriate antibiotic prescribing. Willingness-to-pay (WTP) was calculated for each intervention.ResultsIn the RCT, PC and JA were found to be the most effective interventions to reduce inappropriate antibiotic prescribing, whereas SA was not significantly different from controls. In the DCE however, regardless of treatment intervention received during the RCT, prescribers overwhelmingly preferred SA, followed by PC, then JA. WTP estimates indicated that each intervention would be significantly cheaper to implement than pay-for-performance incentives of $200/month.ConclusionsPrescribing behaviour and stated preferences are not concordant, suggesting that relying on stated preferences alone to inform intervention design may eliminate effective interventions.Trial registration numberNCT01454947; Results.
Proposal for a material with negative thermal expansion
Authors: Abdullah Mikrajuddin 
Published: September 2016

I propose a model of a material that exhibits negative thermal expansion (NTE) properties and criteria for the occurrence of linear and volumetric NTE. I derived the criteria for an arbitrary force between rigid units in the material. These criteria are also discussed specifically for the Lennard–Jones (6–12) potential and in more detail for metal–organic framework (MOF) materials comprising rigid units connected by organic linkers. Qualitatively, the model predictions can explain some observed results. Surprisingly, the model can produce equations for the transition temperature from NTE to positive thermal expansion (PTE), [Formula: see text] K, which is exactly the same as the temperature at which the glass transition begins to occur in most polymers, i.e., [Formula: see text] K.
High-Order Drug Combinations Are Required to Effectively Kill Colorectal Cancer Cells
Authors: Horn Thomas , Ferretti Stéphane , Ebel Nicolas , Tam Angela , Ho Samuel , Harbinski Fred , Farsidjani Ali , Zubrowski Matthew , Sellers William R. , Schlegel Robert , Porter Dale , Morris Erick , Wuerthner Jens , Jeay Sébastien , Greshock Joel , Halilovic Ensar , Garraway Levi A. , Caponigro Giordano , Lehár Joseph 
Published: September 2016

Abstract
Like classical chemotherapy regimens used to treat cancer, targeted therapies will also rely upon polypharmacology, but tools are still lacking to predict which combinations of molecularly targeted drugs may be most efficacious. In this study, we used image-based proliferation and apoptosis assays in colorectal cancer cell lines to systematically investigate the efficacy of combinations of two to six drugs that target critical oncogenic pathways. Drug pairs targeting key signaling pathways resulted in synergies across a broad spectrum of genetic backgrounds but often yielded only cytostatic responses. Enhanced cytotoxicity was observed when additional processes including apoptosis and cell cycle were targeted as part of the combination. In some cases, where cell lines were resistant to paired and tripled drugs, increased expression of antiapoptotic proteins was observed, requiring a fourth-order combination to induce cytotoxicity. Our results illustrate how high-order drug combinations are needed to kill drug-resistant cancer cells, and they also show how systematic drug combination screening together with a molecular understanding of drug responses may help define optimal cocktails to overcome aggressive cancers. Cancer Res; 76(23); 6950–63. ©2016 AACR.