bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Turbine Engine Price Estimation Using Artificial Neural Network
Authors: Rowlands David Olusina , Savill Mark 
Published: October 2018

Gas turbine engine prices vary widely. Any organisation planning to invest in a project involving the use of gas turbine engines, as prime mover, must perform a robust economic analysis to guide the organisations investment decisions. One major element that could greatly influence the outcome of an economic analysis, and eventual organisational decisions and planning, is gas turbine engine acquisition price.
This study applies artificial neural networks to estimate gas turbine engine price. A supervised network learning strategy has been adopted to train the network from a dataset of historical records of gas turbine engine performance parameters and engine price. Numerical gradient checking has been performed to validate the computed cost function with quantified similarity obtained in the order of 10−9. The challenge of neural network overfitting has been minimized by applying a regularization technique. As such, the developed network closes reflects real world observations. To validate the network predictions, the developed neural network has been used to estimate the price of known gas turbine engine units with 95% to 99.9% accuracy.
Condensing Turbine Exhaust Steam in a Steam Surface Condenser Using Multiple Sources of Cooling Water
Authors: Nadig Ranga 
Published: October 2018

Scarcity and restrictions in the use of cooling water has prompted power plant developers to explore multiple sources of cooling mediums to condense turbine exhaust steam in a steam surface condenser. The cooling mediums can have different chemistries dictating selection of different tube and tubesheet materials. The flowrate, inlet temperature and temperature rise for the cooling mediums can be different. Some cooling mediums may not be available during certain times of the year. The resulting steam surface condenser will include multiple smaller tube bundles of various sizes operating with different flowrates and temperatures.
The challenges in designing a condenser that employs multiple sources of cooling medium with different chemistries, flowrates and inlet temperatures are enormous. To ensure reliable operation a number of thermal, hydraulic and mechanical design issues must be carefully evaluated. Determining performance of the entire condenser at off-design conditions with variations in flowrates and inlet temperatures of one or more cooling water streams (or absence thereof) can be complicated.
This paper highlights the major concepts that need to be addressed while designing a steam surface condenser that employs multiple sources of cooling medium to condense the turbine exhaust steam. Critical thermal, hydraulic and mechanical design issues that can impact the performance and reliability of the overall condenser are addressed.
Testing Spark Ignition Engines Converted to Operate on JP-8
Authors: Seibert Michael , DuBois Terry , Scenna Richard , Thampan Tony 
Published: October 2018

Testing was performed on commercially available 1 kW spark ignition generators that were modified to operate on JP-8 and other heavy fuels. This approach is motivated by the US Military mandate that only one fuel, JP-8, be taken to the battlefield, and the increased electrical demands at the squad and platoon level. Small units require a portable power source that can meet their energy demands, particularly battery charging. While diesel engines can operate on JP-8, their weight limits their mobility at the platoon level. Spark ignition engines have better power density at the 1 kW level, but must be modified to burn logistically available fuel.
Multiple approaches have been pursued to enable these engines to operate on JP-8. In the present study, the longer term effects of three approaches are examined and compared to an unmodified spark ignition generator operating on gasoline. These approaches include A) chemically altering the fuel as it flows to the engine to create a higher octane mixture, B) modifying the carburetor and using ether starter fluid to preheat the cylinder, and C) electrically heating the cylinder while modifying the fuel system for direct injection. The different generators were characterized by oil sampling at 15 hour intervals. Oil testing included flash point, viscosity, wear elements, and additives. Oil quality and emissions vary with load. Different approaches to conversion perform better at different loads.
It was determined that multiple start-stop cycles with no load resulted in fuel dilution of the lubricating oil in several of the modified engines. Response varied with some of the modified engines maintaining low fuel dilution similar to the gasoline fueled engine while others indicated 15–20% fuel in the oil. During operation at full load, the modified JP-8 burning generators showed 3–5% fuel dilution in the oil while the unmodified gasoline generator was less than 1%.
These experiments illustrate the challenges in developing portable, reliable JP-8 burning power sources. While further research and development is needed in each approach, it was shown that converted spark ignition engines are a promising path to portable logistic power. Oil analysis was shown to identify future research and development efforts to improve this technology.
Comprehensive Energy Modeling of Tri-Sol: A Three-in-One Solar Concentrating BIPV/Thermal/Daylighting System
Authors: Lawless Sean , Gorthala Ravi 
Published: October 2018

A numerical model was developed in the TRNSYS environment (a transient simulation software) for Tri-Sol, a novel three-in-one solar energy system that produces electricity, hot water, and daylight for commercial buildings, to simulate its annual performance in terms of the three useful energy streams. Even though this model was developed for Tri-Sol, it can also be used for calculating the annual performance of similar concentrating PV/thermal (PV/T) and daylighting systems for various geographical locations. The model simultaneously calculates the codependent electrical and thermal performances, and calculates the useful daylight harvested by the building. The model is versatile and flexible in that any configuration of the modeled system can be properly designed using by changing parameters and inputs inside of TRNSYS.
This model was used to predict the annual performance a single Tri-Sol PV/T module and a single Tri-Sol unit with five such modules as a function of its tilt and geographical location. Then, this model was used to compute the monthly performance of a Tri-Sol array for a 10,000 ft.2 building for varying geographical locations at a fixed tilt angle. These results show the utility and the power of the model for designing combined PV/T-daylighting solar technologies such as Tri-Sol.
Gas Turbine Fouling Offshore: An Analysis of Engine Air Flow
Authors: Madsen Stian , Yildirim Mehmet Serkan , Bakken Lars E. 
Published: October 2018

Optimized operation of gas turbines is discussed for a fleet of eleven LM2500PE engines at a Statoil North Sea offshore field i n Norway. Three engines are generator drivers whilst eight engines are compressor drivers. Several of the compressor drive engines are running at peak load (T5.4 control), hence the production rate is limited by the available power from these engines. The majority of the engines discussed run continuously without redundancy, hence gas turbine uptime is critical for the field’s production and economy.
Two of the compressor drive engines are instrumented with a new static P2 probe in order to have an inlet depression measurement and thus be able to monitor compressor air flow. Compressor air flow has been used as an additional parameter to efficiency, in order to have better analysis methods and better documentation of deterioration rates. The performance gain with online water wash at high water-to-air ratio and upgraded inlet air filter systems, as well as successful operation at longer intervals between offline wash/maintenance stops are thus documented.
An approach for developing a compressor map for mass flow based on field measurements, predictions and deterioration has been performed, as well as correction methods for engine load and ambient conditions in order to be able to compare performance points in various conditions and engine control modes. When monitoring compressor air flow, the Reynolds number effects on axial compressor performance can be analyzed.
Understanding the gas turbine performance deterioration is of vital importance. Trending of its deviation from the engine baseline facilitates load-independent monitoring of the gas turbine’s condition. Instrument resolution and repeatability are key factors in order to have reasonable results on the performance analysis. Based on previous tests and analysis, the compressor air flow rate is the most sensitive parameter for detecting performance deterioration. Unfortunately, gas turbines for offshore operation, are normally not equipped with any air flow measurement devices.
Developmental outcomes of an individualised complementary feeding intervention for stunted children: a substudy from a larger randomised controlled trial in Guatemala
Authors: Martinez Boris , Cardona Sayra , Rodas Patricia , Lubina Meri , Gonzalez Ana , Farley Webb Meghan , Grazioso Maria del Pilar , Rohloff Peter 
Published: October 2018

ObjectiveStunting is a common cause of early child developmental delay; Guatemala has the fourth highest rate of stunting globally. The goal of this study was to examine the impact of an intensive community health worker-led complementary feeding intervention on early child development in Guatemala. We hypothesised that the intervention would improve child development over usual care.DesignA substudy from a larger individually randomised (1:1 allocation ratio), parallel-group superiority trial, with blinding of study staff collecting outcomes data.SettingRural, indigenous Maya communities in Guatemala.Participants210 stunted children (height-for-age z-score ≤−2.5) aged 6–24 months, previously randomised to usual care (106) or an intensive complementary feeding intervention (104). 84 in the intervention and 91 in the usual care arm agreed to participate.InterventionsCommunity health workers conducted monthly home visits for 6 months, providing usual care or individualised complementary feeding education.Main outcome measuresThe primary outcomes were change in z-scores for the subscales of the Bayley Scales of Infant Development (BSID), Third Edition.Results100 individuals were included in the final analysis, 47 in the intervention and 53 in the usual care arm. No statistically significant differences in age-adjusted scores between the arms were observed for any subscale. However, improvements within-subjects in both arms were observed (median duration between measurements 189 days (IQR 182–189)). Mean change for subscales was 0.45 (95% CI 0.23 to 0.67) z-scores in the intervention, and 0.43 (95% CI 0.25 to 0.61) in the usual care arm.ConclusionsAn intensive complementary feeding intervention did not significantly improve developmental outcomes more than usual care in stunted, indigenous Guatemalan children. However, both interventions had significant positive impacts on developmental outcomes.Trial registration numberNCT02509936.StageResults.
Effects of artificial sweeteners on feed palatability and performance in weaned pigs
Authors: Lee Chang Hee , Yun Won , Lee Ji Hwan , Kwak Woo Gi , Oh Han Jin , An Ji Seon , Liu Shu Dong , Cho Jin Ho 
Published: October 2018

In experiment 1, a total of 30 weaning pigs were allotted to three dietary treatments to check the palatability of the dietary feed. Diet treatments were as follows: reference diets = basal diets + 0.05% saccharin (50% Saccharin-natrium), TRT1 = 0.03% saccharin–neotame mix (50% Saccharine-natrium + 2% Neotame), TRT2 = 0.02% neotame (10% Neotame), and TRT3 = 0.02% saccharin–neotame mix (10% Saccharine-natrium + 10% Neotame). TRT2 group was significantly higher than other treatments in palatability (P < 0.05). In experiment 2, a total of 52 weaning pigs were allotted to four dietary treatments. In the average daily gain and average daily feed intake over 1 wk, the TRT2 group was significantly higher than the TRT1 and TRT3 groups (P < 0.05). The concentration of triglyceride in the blood was highest in the TRT1 treated group and the lowest in the TRT2 group (P < 0.05). The Lactobacillus was significantly higher in the TRT2 and TRT3 treatments compared with 0.05% saccharin (50% Saccharine-natrium) (P < 0.05). There was no significant difference in the number of Escherichia coli (P < 0.05). In conclusion, diets supplemented with neotame could improve palatability, and artificial sweeteners can affect nutrient digestibility, blood characteristic, and fecal microbiota.
A Functional Angle of Up to 35° at the Distal Interphalangeal Joint Can Be Achieved with Headless Compression Screw Fusion
Authors: Ingoe Helen M. A. , O’Hare Jonathan F. , Middleton Alan 
Published: October 2018

Background: Arthrodesis of the distal interphalangeal (DIP) joint reliably improves symptomatic arthritis. A range of successful surgical techniques including tension band wiring, plate fixation and headless compression screws have been described and produce stable painless unions. For best functional outcome, the fusion angle should be between 10 and 61 degrees. In the past, it has been difficult to achieve more than 10 degrees of flexion with a headless compression screw. Higher fusion angles have been reported using tension band wiring techniques. However, metalwork prominence is a common problem and may require revision surgery to rectify this. Headless compression screws are reported to cause iatrogenic fractures due to the size of the screw relative to the small diameter of the phalanx. This case series achieves an angle of up to 35 degrees with a good functional outcome.Methods: Open fusion of the DIP joint with a headless cannulated compression screw, of 2.2 mm in diameter, was undertaken in fifteen digits. Patients received standard departmental follow up to radiographic union. Patients self-reported function using the Michigan Hand Questionnaire post operatively. The fusion angles achieved were assessed on postoperative radiographs.Results: All patients went on to a stable union without any patients requiring revision surgery as a result of fracture or protrusion of metalwork. Complications were observed in two patients which included one superficial infection (n = 1) and a discomfort requiring removal of metalwork (n = 1). Functional scores measured post operatively showed favourable outcomes.Conclusions: In this series, successful fusions of the DIP joints, at an angle up to 35 degrees were achieved using small diameter headless compression screws, which provided benefits including early mobilization and favourable functional outcome scores.
Omega-3 Therapy Is Associated With Reduced Gastrointestinal Bleeding in Patients With Continuous-Flow Left Ventricular Assist Device
Authors: Imamura Teruhiko , Nguyen Ann , Rodgers Daniel , Kim Gene , Raikhelkar Jayant , Sarswat Nitasha , Kalantari Sara , Smith Bryan , Chung Ben , Narang Nikhil , Juricek Colleen , Burkhoff Daniel , Song Tae , Ota Takeyoshi , Jeevanandam Valluvan , Sayer Gabriel , Uriel Nir 
Published: October 2018

Background
Gastrointestinal bleeding (GIB) is a common complication seen in patients supported with left ventricular assist devices (LVADs) and is related to increased inflammation and angiogenesis. Omega-3 is an unsaturated fatty acid that possesses anti-inflammatory and antiangiogenic properties. This study aims to assess the prophylactic efficacy of treatment with omega-3 on the incidence of GIB in LVAD patients.

Methods and Results

Among consecutive 166 LVAD patients enrolled in this analysis, 30 patients (49 years old and 26 male) received 4 g/d of omega-3 therapy for 310±87 days and 136 patients in the control group (58 years old and 98 male) were observed for 302±102 days. One-year GIB-free rate was significantly higher in the omega-3 group as compared with the control group (97% versus 73%;
P
=0.02). Omega-3 therapy was associated with the occurrence of GIB in both the univariate (hazard ratio, 0.12; 95% CI, 0.02–0.91;
P
=0.040) and multivariate Cox proportional hazard ratio analyses (hazard ratio, 0.13; 95% CI, 0.02–0.98;
P
=0.047). The frequency of GIB was significantly lower in the omega-3 group (0.08±0.42 versus 0.37±0.93 events/y;
P
=0.01), accompanied by significantly lower blood product transfusion and shorter days in the hospital. The frequency of GIB remained lower among the omega-3 group after matching for patient background characteristics (96% versus 73%,
P
=0.028).

Conclusions
LVAD patients treated with omega-3 had a significant increase in freedom from GIB. A randomized controlled study is warranted to evaluate the use of omega-3 in LVAD patients.
Later Wet Seasons with More Intense Rainfall over Africa under Future Climate Change
Authors: Dunning Caroline M. , Black Emily , Allan Richard P. 
Published: October 2018

AbstractChanges in the seasonality of precipitation over Africa have high potential for detrimental socioeconomic impacts due to high societal dependence upon seasonal rainfall. Here, for the first time we conduct a continental-scale analysis of changes in wet season characteristics under the RCP4.5 and RCP8.5 climate projection scenarios across an ensemble of CMIP5 models using an objective methodology to determine the onset and cessation of the wet season. A delay in the wet season over West Africa and the Sahel of over 5–10 days on average, and later onset of the wet season over southern Africa, is identified and associated with increasing strength of the Saharan heat low in late boreal summer and a northward shift in the position of the tropical rain belt over August–December. Over the Horn of Africa rainfall during the “short rains” season is projected to increase by over 100 mm on average by the end of the twenty-first century under the RCP8.5 scenario. Average rainfall per rainy day is projected to increase, while the number of rainy days in the wet season declines in regions of stable or declining rainfall (western and southern Africa) and remains constant in central Africa, where rainfall is projected to increase. Adaptation strategies should account for shorter wet seasons, increasing rainfall intensity, and decreasing rainfall frequency, which will have implications for crop yields and surface water supplies.
Neural Networks for Postprocessing Ensemble Weather Forecasts
Authors: Rasp Stephan , Lerch Sebastian 
Published: October 2018

AbstractEnsemble weather predictions require statistical postprocessing of systematic errors to obtain reliable and accurate probabilistic forecasts. Traditionally, this is accomplished with distributional regression models in which the parameters of a predictive distribution are estimated from a training period. We propose a flexible alternative based on neural networks that can incorporate nonlinear relationships between arbitrary predictor variables and forecast distribution parameters that are automatically learned in a data-driven way rather than requiring prespecified link functions. In a case study of 2-m temperature forecasts at surface stations in Germany, the neural network approach significantly outperforms benchmark postprocessing methods while being computationally more affordable. Key components to this improvement are the use of auxiliary predictor variables and station-specific information with the help of embeddings. Furthermore, the trained neural network can be used to gain insight into the importance of meteorological variables, thereby challenging the notion of neural networks as uninterpretable black boxes. Our approach can easily be extended to other statistical postprocessing and forecasting problems. We anticipate that recent advances in deep learning combined with the ever-increasing amounts of model and observation data will transform the postprocessing of numerical weather forecasts in the coming decade.
Integration of a Ground-Based Lightning Warning System into a Mining Operation in the Democratic Republic of the Congo
Authors: Clulow Alistair D. , Strydom Sheldon , Grant Bryan , Savage Michael J. , Everson Colin S. 
Published: October 2018

Abstract
Central Africa is a global lightning hot spot, with the tropical areas including the top 10 highest lightning-flash-rate densities in the world. There are no lightning-locating-system networks available across most of Africa, however, and it becomes necessary to make use of real-time, ground-based lightning early warning systems. Such a system was established in the southern Congo basin at the Kinsevere copper mine and has been operational since early 2015. The early warning system includes an electrical-field meter and a lightning-flash sensor, which produce two states of warning. Two years of data (July 2015–June 2016 and July 2016–July 2017) indicated a clear annual and daily peak in lightning activity, with an average lightning warning duration of 1.18 h and a maximum storm duration of 8.60 h. The seasonal flash occurrence was reasonably constant over the two years but was variable at a monthly level during the lightning season. Analysis of alarm state showed that the majority of events start with an escalation to an alarm state of 2 but that, over two years, 69.3% escalated further to an alarm state of 3. Alarm-duration analysis indicated that more time was spent in alarm state 3 (warning) than alarm state 2 (caution). It was concluded that a single warning state would be suitable at this location and would simplify the warning system but that appropriate alarm-activation thresholds in electric field and flash distance need further assessment.
Lessons from the Left in Lima: Susana Villarán and the Fleeting Return of Progressive Politics to City Hall
Authors: Dosh Paul , Coyoli Julia Smith 
Published: October 2018

Amid a rightward shift in Latin America, how can the left gain ground in cities characterized by entrenched neoliberalism? The case of Susana Villarán, the progressive mayor who led Lima, Peru, from 2011 to 2014, illustrates the uphill battle facing the left. Villarán’s surprise election put a leftist in City Hall for the first time in 25 years. She confronted unrelenting opposition but defied expectations and beat back a recall election only to face a punishing defeat in her reelection bid. Weak policy-making capacity and a lack of party machinery forced her to expend all her political capital on the recall battle, leaving her with nothing to secure reelection. Her trajectory suggests an important lesson for progressives in cities where the left is weak: a headline-grabbing win by an individual leftist is no substitute for a robust left base. Absent the latter, simply electing a progressive mayor is likely to prove a fleeting victory. En medio de un movimiento hacia la derecha en América Latina, ¿cómo puede la izquierda ganar terreno en ciudades caracterizadas por un neoliberalismo atrincherado? El caso de Susana Villarán, la alcaldesa progresista que gobernó Lima, Perú, de 2011 a 2014, ilustra la batalla cuesta arriba que enfrenta la izquierda. La sorprendente victoria electoral de Villarán logró colocar a alguien de la izquierda en la alcaldía por primera vez en 25 años. Ella se enfrentó a una oposición implacable, pero desafió las expectativas y ganó una revocatoria solo para enfrentar una derrota contundente en su intento por la reelección. Dado la poca capacidad para crear políticas públicas y la ausencia de una maquinaria electoral partidista, se vio forzada a gastar todo su capital político en la batalla por la revocatoria, lo cual la dejó sin recursos para conseguir la reelección. Su trayectoria presenta una lección importante para los progresistas en ciudades donde la izquierda es débil: una victoria llamativa por parte de un individuo de la izquierda no funge como substituto para una base robusta de la izquierda. Lo anterior sugiere que cuando esta base se encuentra ausente, es probable que el simple acto de elegir un alcalde progresista sea una victoria efímera.