bluuebunny/crossref_metadata_2025_split huggingface dataset:
Principles and Sensitivity Analysis of Automatic Calibration of MPD Methods Based on Dual-Gradient Drilling Solutions
Authors: Cayeux E.. , Daireaux B.. , Dvergsnes E. W. , Siahaan H.. , Gravdal J. E. 
Published: September 2014

Abstract
Dual-gradient drilling (DGD) solutions have been developed to work with greater margins while drilling in deep water environments by mirroring hydrostatic pressure conditions that are closer to the natural ones. Recent attempts have been undertaken to use DGD to actively control the downhole pressure and therefore turning them into managed pressure drilling (MPD) solutions. The pressure control strategy requires the knowledge of how pressure will change along the borehole as a function of the drilling parameters and therefore needs to use numerical hydraulic models. However, the accuracy of the prediction of pressure calculations depends on a certain number of parameters that are not necessarily well known. Some of those significant factors are well defined but are not necessarily measured as extensively as it would have been required. Others are subject to the actual downhole conditions and may change with time. Therefore, they are, in many instances, difficult to assess with enough certainty. As a result, it is necessary to constantly calibrate the downhole pressure calculations in order to match observed values at controlled positions. This calibration process is usually done manually by a human operator, leaving the possibility for possible misinterpretations of the actual calibration data and consequently a potentially erroneous control of the downhole pressure by the MPD control algorithm.
In this paper, we review the sources of uncertainties that can affect the accuracy of the downhole pressure calculations. Thereafter, we explain how automatic calibration of the numerical models can be made in order to match reference measurements. The proposed method also allows for an evaluation of the accuracy by which the downhole pressure calculations can be made. In conjunction with the required precision to control the downhole pressure during a drilling operation, it is possible to assess whether additional measurements or working procedures should be implemented prior to an MPD dual-gradient operation with tight constraints.
Prediction of Gas-Pulsation Frequency To Reduce Slug Length in Gas/Liquid Horizontal-Pipe Flow
Authors: Kadri Usama 
Published: September 2014

Summary
Very long slugs reaching several hundreds of pipe diameters may appear when transporting gas and liquid in horizontal pipes. Such slugs may cause serious operational and system failures. One could avoid the long slugs by pulsating the gas phase at the inlet at a specific range of frequencies. The present paper provides a simplified mathematical expression for the optimum gas-pulsation frequency. Predictions of the pulsation frequency for different flow conditions and pipe diameters are presented. Comparisons with available experiments are satisfactory.
Genetic Diversity, Linkage Disequilibrium, and Genome Evolution in Soft Winter Wheat
Authors: Cabrera Antonio , Souza Ed , Guttieri Mary , Sturbaum Anne , Hoffstetter Amber , Sneller Clay 
Published: September 2014

ABSTRACTUnderstanding genetic diversity within a breeding population is fundamental to its efficient exploitation. The advent of new high‐throughput marker systems offers the opportunity to expand the scope and depth of our investigation of diversity. Our objective was to analyze the genetic diversity of two populations of soft winter wheat (SW) adapted to the eastern United States. The historical population (HP) consisted of 187 lines released or developed from 1808 to 2005. The elite population (EP) consisted of 449 elite modern lines from the Ohio State University breeding program. The HP was genotyped with single nucleotide polymorphism (SNP) and diversity array technology (DArT) markers, while the EP was genotyped with DArTs. Population structure comprised of up to five subgroups was observed on the HP using either SNP or DArT markers and up to six subgroups on the EP. The subgroups could be partly explained by year of release (in HP), class (red versus white wheat) and pedigree (in the EP). Diversity appeared to increase with time; an estimated 11% of the genome exhibited a pronounced linear change over time, while evidence of more subtle changes abound. The DArT markers were associated with greater genome changes than SNP markers. Linkage disequilibrium (LD) that produced an r2 of 0.2 or greater extended to about 5 cM in both populations. The extent of LD decay varied widely across the genome. In conclusion, SW in the eastern United States has a moderate level of structure, appears quite diverse, and diversity may be increasing.
Effects of S1 Recurrent Selection for Provitamin A Carotenoid Content for Three Open‐Pollinated Maize Cultivars
Authors: Dhliwayo Thanda , Palacios‐Rojas Natalia , Crossa Jose , Pixley Kevin V. 
Published: September 2014

ABSTRACTMaize (Zea mays L.) cultivars with increased concentrations of provitamin A (proVA) carotenoids can improve the health of millions of consumers who are vitamin A deficient and rely on maize as a staple food. Three open‐pollinated maize cultivars (OPC) were subjected to three cycles of S1 recurrent selection for increased proVA concentration. Agronomic performance of Cycles 0, 1, 2, and 3 for each OPC was evaluated using three replications at 10 locations, and changes in proVA concentration were assessed for hand‐pollinated grain produced at two sites. Selection resulted in significant (P < 0.01 for 11, and P < 0.05 for 1 occurrence) linear increases of 25 to 67% per cycle for total proVA, 28 to 60% for β‐carotene, 18 to 70% for β‐cryptoxanthin, and 11 to 46% for zeaxanthin. These findings are especially significant because, in contrast to recent trends, they demonstrate the feasibility of developing proVA‐enhanced maize while meeting nutritionists’ recommendations not to sacrifice β‐cryptoxanthin and zeaxanthin to increase β‐carotene concentration in grain. Grain yield increased in one but decreased (P < 0.01) in two of the OPCs, and we hypothesize that linkage drag associated with proVA‐enhancing genes from exotic donor lines may be responsible for the negative trends. We conclude that breeding proVA‐enriched maize without sacrificing β‐cryptoxanthin and zeaxanthin concentrations is feasible, but that (i) it remains unknown whether such approaches can achieve the high concentrations of proVA reported elsewhere by using marker‐assisted selection for genes that favor β‐carotene accumulation, and (ii) that grain yield and agronomic performance should be simultaneously selected if useful cultivars are desired.
Phytochemical and Nutraceutical Changes during Recurrent Selection for Storage Pest Resistance in Tropical Maize
Authors: García‐Lara Silverio , Bergvinson David J. 
Published: September 2014

ABSTRACTMaize (Zea mays L.) is a staple crop used for subsistence by smallholder farmers around the world, who usually store grain for gradual use. During the course of storage, losses due to storage pests often reach 20%. Over three cycles of recurrent selection, population improvement to develop sources of resistance to the larger grain borer (Prostephanus truncates) and the maize weevil (Sitophilus zeamais) resulted in a new population called Population 84 (P84). The objective of this study was to evaluate the biophysical, phytochemical, and nutraceutical profile changes in P84 derived from three cycles of selection for resistance. Insect resistance parameters were evaluated using bioassay and biophysical, phytochemical, and nutraceutical parameters. Resistance to storage pests increased by two‐ to threefold after three cycles of selection for maize weevil and larger grain borer, respectively. The major factors related to enhanced resistance are kernel hardness (10% increase) and proportion of pericarp (68% increase) in the kernel. Comparing the phytochemical composition of the pericarp cell wall before and after selection revealed an elevated level of cell wall–bound components (42% increase), including ferulic and diferulic acids (14% and twofold increase, respectively). Increases of 18% in free phenolic acid were found in the endosperm. A significant association between insect resistance with antioxidant activity (r > 0.75) establishes the possibility of seeking increased nutrients beneficial for human health in the same maize germplasm selected for increased insect resistance and stemming from the same compounds. Population 84 is a good source for resistance to postharvest pests with enhanced nutraceutical properties.
Environmental Variability and/or Stability of Stem Fiber Content and Digestibility in Alfalfa
Authors: Lamb JoAnn F. S. , Jung Hans‐Joachim G. , Samac Deborah A. 
Published: September 2014

ABSTRACTHigh concentration and low digestibility of stem fiber constituents in herbage of alfalfa (Medicago sativa L.) can limit dry matter intake and energy availability in ruminant (dairy and beef) production systems. Stem neutral detergent fiber (NDF), acid detergent lignin (ADL), and stem in vitro neutral detergent fiber digestibility (IVNDFD) are impacted by the environment. We identified 45 individual alfalfa plants that differed in stem NDF and ADL concentrations, ADL as a proportion of NDF (ADL/NDF), and stem IVNDFD after 16 and 96 h of digestion. All plants were vegetatively propagated and established in replicated trials and sampled 12 times (spring and early and late summer harvests for 2 yr at two field locations). A subset of clones were evaluated in two greenhouses and harvested for two regrowth cycles. Stability analyses demonstrated that stem ADL/NDF, NDF, and 96‐h IVNDFD were more environmentally stable among the alfalfa clones in the field environments tested than stem 16‐h IVNDFD or ADL. All stem fiber quality traits were considered consistent between the two field environments, but no relationship in trait responses were demonstrated between field and greenhouse environments. These results suggested that stem 96‐h IVNDFD, NDF, and ADL/NDF would be the traits to use in a field selection program to develop alfalfa with improved nutrient value.
Career Motivations, Perceptions of the Future of Dentistry and Preferred Dental Specialties Among Saudi Dental Students
Authors: Halawany Hassan S 
Published: September 2014

Aim:The purpose of this study was to determine the career motivations, perceptions of the future of dentistry and preferred postgraduate specialties of Saudi dental students.Methods:A pretested, self-administered, 16-item questionnaire was distributed to first- through fifth-year dental students at King Saud University in Saudi Arabia. Descriptive statistics were calculated, and the level of significance was set at 5%.Results:Of the 530 potential participants, 329 students (198 male and 131 female respondents) completed the questionnaire. High professional status (71.4%), a secure career (67.8%), a high income (78.1%), flexible working hours (54.4%), a wide range of career options after graduation (59.3%), opportunities for self-employment (69.3%) and good job opportunities abroad (65.3%) were endorsed to a great/considerable extent by the respondents. “It takes time to establish a practice” (62.3%), “Postgraduate education is a necessity” (72.4%) and “The increasing number of dental institutions is a threat to the profession” (59.3%) were endorsed to a great or considerable extent by the respondents. The most popular specialty among the male students was oral maxillofacial surgery (20.1%) and among female students was operative dentistry (23.4%).Conclusion:The career motivations of this group of dental students seemed to relate to socioeconomic aspects of dentistry and perceptions of the future of dentistry seemed to relate to the need for postgraduate education.
Evaluation of Light Curing Distance and Mylar Strips Color on Surface Hardness of Two Different Dental Composite Resins
Authors: Mousavinasab Seyed Mostafa , Barekatain Mehrdad , Sadeghi Elahe , Nourbakhshian Farzaneh , Davoudi Amin 
Published: September 2014

Introduction:Hardness is one of the basic properties of dental materials, specially composite resins which is relevant to their polymerization. The aim of this study was to evaluate the effect of light curing distance and the color of clear Mylar strips on surface hardness of Silorane-based (SCR) and Methacrylate-based composite resins (MCR).Materials and methods:40 samples of MCRs (Filtek Z250) and SCRs (Filtek P90) were prepared in size of 5 mm×2 mm (80 samples in total). The samples divided into 8 groups (10 samples in each one) based on the color of clear Mylar strips (white or blue) and distance from light curing source (0 mm or 2 mm). All the samples cured for 40 second and stored in incubator for 24 hours in 37°C temperature. Surface hardness test was done by Vickers test machine and the collected data were analyzed by one-way ANOVA and paired T-test by using SPSS software version 13 at significant level of 0.05.Results:MCRs cured with blue Mylar strips from 0 mm distance had the highest (114.5 kg/mm2) and SCRs cured with white Mylar strips from 2 mm distance had the lowest (42.2 kg/mm2) mean of surface hardness. Also, the results of comparison among SCRs and MCRs showed significant differences among all groups (all P values <0.01).Conclusion:The hardness decreased as the distance increased and the blue Mylar strips provided higher hardness than clear ones. Also, Filtek Z250 showed higher hardness compared to Filtek P90.
Analysis of Coal With Coal-Mule and Biomass Co-Combustion in Slurry Form/Analiza Współspalania Węgla Z Mułem Węglowym I Biomasą W Postaci Zawiesiny
Authors: Kijo-Kleczkowska Agnieszka 
Published: September 2014

Abstract
Combustion technology of coal-water fuels creates a number of new possibilities to organize the combustion process fulfilling contemporary requirements e. g in the environment protection. Therefore an in-depth analysis is necessary to examine the technical application of coal as energy fuel in the form of suspension. The paper undertakes the complex research of the coal with coal-mule and biomass co-combustion. The mathematical model enables the prognosis for change of the surface and the centre temperatures and a mass loss of the fuel during combustion in air and in the fluidized bed.
Chances and Threats of Hard Coal Mining Development in Poland – The Results of Experts Research/Szanse I Zagrożenia Dla Rozwoju Górnictwa Węgla Kamiennego W Polsce – Wyniki Badań Eksperckich
Authors: Dubiński Józef , Turek Marian 
Published: September 2014

Abstract
The actual situation of hard coal mining in Poland has been presented. In particular, these factors, which have impact on the competiveness of mining sector were highlighted and need of its improving has been stressed. Outlining present situation of hard coal mining an attention was paid to its specific threats. The primary analytical material is based on the results of questionnaire conducted among 92 specialists and experts from the mining sector. The questions were related to chances and threats for development of hard coal mining in Poland. The factors determining them were grouped in such domains as economy, technology, geology, social and law aspects. Moreover, the special attention was paid to the problem of increasing and high costs of coal production which constitute significant threat for the financial and economic situation of the mining enterprises. Also the adverse influence of these high cost on the competitiveness of Polish hard coal with other world producers and with other energy carriers was emphasized. The conclusions summarize the achieved results of analysis.
Electromagnetic Compatibility Tests of Mining Mobile Inspection Robot/Badania Kompatybilności Elektromagnetycznej Górniczego Mobilnego Robota Inspekcyjnego
Authors: Kasprzyczak Leszek , Pietrzak Roman 
Published: September 2014

Abstract
The articles presents the methodology and results of electromagnetic compatibility tests conducted on a non-commercial prototype of the Mining Mobile Inspection Robot. The tests were carried out in an accredited laboratory of the Institute of Innovative Technologies EMAG in compliance with European standards harmonized with the 2004/108/EC (EMC) directive. In the article the testing stands were characterized along with the test types, performance criteria and test results. The testing methodology and the selection of standards can be a pattern to conduct electromagnetic compatibility tests for similar products designed for the mining industry.
Maintenance Plan for a Fleet of Rotary Drill Rigs/Harmonogram Utrzymania I Konserwacji Floty Obrotowych Urządzeń Wiertniczych
Authors: Rahimdel Mohammad Javad , Ataei Mohammad , Khalokakaei Reza , Hoseinie Seyed Hadi 
Published: September 2014

Abstract
In this paper a basic methodology was used for the reliability modeling and developing a maintenance program for a fleet of four drilling rigs. Failure and performance data was collected from Sarcheshmeh Copper Mine in Iran for a two-year period. Then the available data was classified and analyzed and reliability of all subsystems and whole rigs were modeled and studied. The failure data showed that, in all rigs, electrical, hydraulic and drilling systems are the most frequent failing subsystems of the machine. The reliability analysis showed that transmission system is the most reliable subsystem in all studied rigs. In order to calculate the reliability of whole fleet, it was assumed that operation of at least two drilling rigs is essential for satisfying the production goals. Therefore, probabilistic possibility of all fleet’s states were calculated. In this paper, 80% is selected as the desired level of reliability for developing of preventive maintenance program for each subsystem of the drilling rigs. Finally, the practical approaches were suggested for improving the maintenance operation and productivity of the studied fleet.
The Hot-Wire Anemometer/Anemometr Z Grzanym Włóknem
Authors: Kiełbasa Jan 
Published: September 2014

Abstract
This study analyses the behaviour of a hot-wire anemometer incorporated into a bridge circuit in the function of the voltage Uz supplying the bridge circuit and hence the current Iw flowing through the hot wire. The dependence of differential voltage ΔU on Iw and the value of derivative d(ΔU)/dIw as a function of the current supplying the hot-wire element were determined. These data enable the determination of working conditions of the constant-resistance (i.e. the constant-temperature) hot-wire anemometer.
Verification of Mathematical Description of Changes in Air Temperature and Humidity in Headings Ventilated with Auxiliary Ventilation System/Weryfikacja Metematycznego Opisu Zmian Temperatury I Wilgotności Powietrza W Wyrobiskach Przewietrzanych Lutniciągiem Tłoczącym Z Dadatkowym Wentylatorem O Zmienianej Prędkości Obrotowej
Authors: Nowak Bernard , Piątek Jan 
Published: September 2014

Abstract
The article presents verification of the mathematical model which was developed in earlier works, describing, through distributions of temperature, specific humidity, and flow rate of both fresh and exhaust air in the dead end headings ventilated with forcing duct line ventilation system, the climatic conditions existing in those headings. On the route of the considered duct line, an additional fan with a variable rotational speed was installed in order to avoid recirculation of the air between the inside of the duct line and the heading. The task of this auxiliary fan is an increase in the volumetric flow rate of fresh air at the mine face. The above-mentioned verification was based on a comparison of the calculation results obtained from the numerical solution of ordinary differential equations of the first order and algebraic equations with the results of measurements carried out in the selected mine heading. Wide comparative material was obtained by changing the location of the auxiliary fan in the duct line for a given heading length, and the heading length itself. 14 research variants were obtained in this way, in which, in addition to the already mentioned temperatures and humidity of the air, also the rotor speeds of the auxiliary fan were compared. The results of calculations and measurements have been presented in a graphical form. Their comparison was carried out using statistical methods.
Methodology of Calculation the Terminal Settling Velocity Distribution of Irregular Particles for High Values of the Reynold’s Number/Metodologia Wyliczania Rozkładu Granicznej Prędkości Opadania Ziaren Nieregularnych Dla Wysokich Wartości Liczb Reynoldsa
Authors: Surowiak Agnieszka , Brożek Marian 
Published: September 2014

Abstract
Settling velocity of particles, which is the main parameter of jig separation, is affected by physical (density) and the geometrical properties (size and shape) of particles. The authors worked out a calculation algorithm of particles settling velocity distribution for irregular particles assuming that the density of particles, their size and shape constitute independent random variables of fixed distributions. Applying theorems of probability, concerning distributions function of random variables, the authors present general formula of probability density function of settling velocity irregular particles for the turbulent motion. The distributions of settling velocity of irregular particles were calculated utilizing industrial sample. The measurements were executed and the histograms of distributions of volume and dynamic shape coefficient, were drawn. The separation accuracy was measured by the change of process imperfection of irregular particles in relation to spherical ones, resulting from the distribution of particles settling velocity.
The Role of Geostationary Earth Orbit Communication Satellites in Chinese Area Positioning System
Authors: Ma Lihua 
Published: September 2014

Abstract
The Chinese Area Positioning System (CAPS) is an area positioning system based on Geostationary Earth Orbit (GEO) communication satellites. Transponders on the satellites are used to retransmit navigation message and ranging signals generated from the ground master station, while users receive navigation signals to perform navigation and positioning tasks. Meanwhile, CAPS also develops bidirectional communication receivers using abundant transponders resources on Slightly Inclined Geostationary Orbit (SIGSO) communication satellites, thus realizing integration of navigation and communication in the coverage region.
Anatomical variations of the sphenoid sinus - a study of 200 cases -
Authors: Lupascu M. , Comsa Gh. I. , Zainea V. 
Published: September 2014

Abstract
Our study on the anatomical variation of pneumatisation of the sphenoid sinuses was performed on 200 tomographical studies, evaluating the anatomical variations of the sphenoid sinuses and the Onodi cells, the types of pneumatisation according with the types described by Hammer and Radberg, as well as the extensions of pneumatisation towards the anterior clinoid processes, pterygoid processes and sphenoidal wings; the frequency of intrasphenoidal protrusions and dehiscences of internal carotid artery, optic nerve, Vidian canal and foramen rotundum and the presence of primary and secondary septa attached to their canals.