bluuebunny/crossref_metadata_2025 huggingface dataset:
Case History of Laboratory Design and Field Application of Bio-Polymer Free Fluids for an Open Hole Gravel Pack
Authors: Allogo C. M , Luyster M.. , Nguyen C.. , Ravitz R.. , Perardel A..
Published: September 2014

An operator and its partners operating in the Gulf of Guinea decided to drill and complete a horizontal open hole gravel pack well in deep water field to optimize production. Minimizing formation damage during the drilling and completion operation was a primaryconcern. In addition to preventing formation damage, the relative narrow pressure window, scaling tendency of formation water with divalent brines were concerns requiring the implementation of new fluid systems to mitigate the aforementioned issues. This required intensive laboratory design process and preplanning. Drilling and completion fluids were designed and customized based on results from tests previously mentioned. Compatibility between all fluids with formation water were assessed at 180, 225 and 250°F. Return permeability simulated drilling and completion sequences to prove non damaging properties. Logistic field challenges to handle systems were successfully managed in a remote location by sufficient pre-planning. Selected fluid systems were used in the field to successfully drill and complete the alpha beta open hole gravel pack well, with higher than expected production. Design process, results and field application parameters are discussed in this paper.
Learning from Field Measurements: Engineering Method to Improve Cement Returns in Riserless Deepwater Jobs
Authors: Dooply Mohammed , Peternell Ana , Long Jeffrey
Published: September 2014

With the increased importance of achieving zonal isolation in the shallow riserless sections of deepwater wells, it has become critical to understand the results of the cement placement. Riserless cementing job design has historically been a static process largely independent of the drilling parameters, particularly in these large-diameter boreholes.

Variable borehole shape and quality affects the wellbore cleaning, wellbore stability while drilling and the smooth operation of the casing run. Borehole quality can also compromise cement placement efficiency and mud displacement mechanics. It has become increasingly important to develop a greater understanding of the impact that borehole size and the identification of borehole degradation have in cementing design and placement, to increase the likelihood of achieving zonal isolation objectives.

Caliper tools provide an explicit method that uses physical measurements to evaluate not only wellbore quality but also formation characteristics. Caliper measurement is used to optimize the cementing design by adjusting key parameters such as cement slurry volumes, centralization, pre-flush volumes, and fluids pump rate, so that effective mud removal and optimized cement placement are achieved.

A review the current practices of field measurements and observations to understand and detect cement returns in the deepwater drilling environment and also the applications and key learnings from the engineering workflow led to new development of tools to improve the understanding of the cement volumes required for these particular top hole sections.
Planning for a Necessary Evil in Deepwater Operations: Remedial Cementing
Authors: Shine Joe
Published: September 2014

Drilling operations are presented with challenges for both normal and complex wellbore environments with a focus on minimizing nonproductive time while successfully achieving the well objectives. In some cases, it is likely to reach the well objectives and remedial cementing may play a significant part whether it is due to exploration or wildcat-type wells, complex well construction, or the geological uncertainties. As a necessary evil, being able to plan for contingencies and success when faced with remedial cementing applications can reduce the potential replication of treatments and improve the extent of nonproductive time.

When these situations arise during deepwater operations, there are challenges beyond the traditional cementing scope of work such as multiple temperature and pressure gradients, subsea equipment, and large-bore tubulars. Drilling deeper these factors may also include lithology, wellhead clearances, stuck pipe, failure of barriers, and/or an unstable well. Furthermore, traditional service tools find limited success with remedial operations in large-bore casing/tubulars, often requiring alternative solutions, including pumping through bottom hole assemblies, using inflatable packers, and developing other non-traditional placement techniques.

This paper will present methods to improve the success of cement placement while performing remedial cementing operations in an effort to reduce nonproductive time and execute common contingency planning. In addition, specific well situations and events executing these methods will demonstrate the impacts to remediate the necessary evil.
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

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

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.
Predicting Maize Phenology: Intercomparison of Functions for Developmental Response to Temperature
Authors: Kumudini S. , Andrade F. H. , Boote K. J. , Brown G. A. , Dzotsi K. A. , Edmeades G. O. , Gocken T. , Goodwin M. , Halter A. L. , Hammer G. L. , Hatfield J. L. , Jones J. W. , Kemanian A. R. , Kim S.-H. , Kiniry J. , Lizaso J. I. , Nendel C. , Nielsen R. L. , Parent B. , Stöckle C. O. , Tardieu F. , Thomison P. R. , Timlin D. J. , Vyn T. J. , Wallach D. , Yang H. S. , Tollenaar M.
Published: September 2014

Accurate prediction of phenological development in maize (Zea mays L.) is fundamental to determining crop adaptation and yield potential. A number of thermal functions are used in crop models, but their relative precision in predicting maize development has not been quantified. The objectives of this study were (i) to evaluate the precision of eight thermal functions, (ii) to assess the effects of source data on the ability to differentiate among thermal functions, and (iii) to attribute the precision of thermal functions to their response across various temperature ranges. Data sets used in this study represent >1000 distinct maize hybrids, >50 geographic locations, and multiple planting dates and years. Thermal functions and calendar days were evaluated and grouped based on their temperature response and derivation as empirical linear, empirical nonlinear, and process‐based functions. Precision in predicting phase durations from planting to anthesis or silking and from silking to physiological maturity was evaluated. Large data sets enabled increased differentiation of thermal functions, even when smaller data sets contained orthogonal, multi‐location and ‐year data. At the highest level of differentiation, precision of thermal functions was in the order calendar days < empirical linear < process based < empirical nonlinear. Precision was associated with relatively low temperature sensitivity across the 10 to 26°C range. In contrast to other thermal functions, process‐based functions were derived using supra‐optimal temperatures, and consequently, they may better represent the developmental response of maize to supra‐optimal temperatures. Supra‐optimal temperatures could be more prevalent under future climate‐change scenarios, but data sets in this study contained few data in that range.
Opportunities Exist to Improve Alfalfa and Manure Nitrogen Crediting in Corn following Alfalfa
Authors: Yost Matt A. , Coulter Jeffrey A. , Russelle Michael P. , Davenport Mae A.
Published: September 2014

We conducted a survey of Minnesota growers to determine the adoption of extension N rate guidelines for fertilizer and manure for first‐ and second‐year corn (Zea mays L.) following alfalfa (Medicago sativa L.) (AC and ACC, respectively). There were 421 and 273 valid responses for AC and ACC, respectively. Adoption rates during 2009 to 2011 were higher without manure; almost one‐half of respondents adopted N rate guidelines for AC and about one‐third adopted for ACC. With manure, adoption decreased to only 29% for AC and 25% for ACC. In all cases, the odds of nonadoption increased when corn followed fair or good alfalfa stands relative to poor stands. In most cases, the odds of nonadoption also increased when corn yield goal was used as a factor for determining fertilizer N rates for AC and ACC. Nonadoption of N rate guidelines in AC increased the odds of nonadoption in ACC, whether manure was applied or not. Respondents’ past experience and soil testing lab recommendations were rated as the most reliable information sources for N management. The high frequency and rate of excess N application in this rotation highlights a pressing need for enhanced research and stakeholder engagement to increase adoption of alfalfa and manure N credits. In particular, there is a need to discourage manure applications to AC and ACC, which often require little or no applied N beyond alfalfa N credits. Efforts should involve multiple stakeholders and may require improved, more site‐specific, N rate guidelines for AC and ACC.
Potato Gas Exchange Response to Drought Cycles under Elevated Carbon Dioxide
Authors: Fleisher David H. , Barnaby Jinyoung , Sicher Richard , Resop Jonathan P. , Timlin D. J. , Reddy V. R.
Published: September 2014

Elevated carbon dioxide (CO2) influences photosynthesis (AN), transpiration (ET), and water use efficiency (WUE) for well‐watered potato (Solanum tuberosumL.). Little is known regarding effects of short‐term drought and CO2. Two experiments, differing in the quantity of solar radiation, were conducted in soil‐plant‐atmosphere‐research chambers. Plants were grown at ambient (aCO2) or twice‐ambient CO2(eCO2) and received one of three irrigation treatments: no water stress (C), short‐term (11–16 d) water‐withholding during vegetative and post‐tuber initiation stages (VR), or post‐tuber initiation (R) only. Canopy conductance to CO2transfer (τ) and water vapor (Gv), light use efficiency (α), dailyAN, and ET decreased at the onset of each drought and were correlated with volumetric water content. The rate of decrease was similar for R and VR.Gvdeclined more sharply thanAN, resulting in higher WUE. SeasonalANdeclined with the pattern of C > R > VR and was higher for eCO2C and R treatments. Seasonal WUE was higher for eCO2at all irrigation treatments. Total dry matter, harvest index, and leaf area were reduced (p< 0.05) for droughted treatments and total dry matter and harvest index were also higher for eCO2VR pots. Relative responses to drought and CO2were similar among experiments, with greater magnitude of response under high solar radiation. Findings were similar to those reported under longer‐term water‐withholding studies, suggesting that interactions between CO2and drought on carbon assimilation and water use are conserved across production zones with varying radiation and rainfall patterns.
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

Understanding 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

Maize (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

Maize (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

High 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.
Spatially Nonstationary Relationships between Copper Accumulation in Rice Grain and Some Related Soil Properties in Paddy Fields at a Regional Scale
Authors: Qu Mingkai , Li Weidong , Zhang Chuanrong , Huang Biao , Zhao Yongcun
Published: September 2014

Previous studies on the relationships between trace metal accumulation in plants and related soil properties have commonly assumed spatial stationarity by using traditional (global) regression techniques such as ordinary least squares regression (OLS). In this study, geographically weighted regression (GWR) was used to explore the relationships between the Cu concentration in rice (Oryza sativaL.) grain and a set of perceived soil properties, including total Cu in the soil, pH, and soil organic matter in Jiaxing, China. It was found that GWR performed much better than OLS in characterizing the relationships, in terms of the coefficient of determination (R2), corrected Akaike information criterion, ANOVA test, sum of squared residuals, and spatial autocorrelations of residuals. The GWR analysis showed that the relationships between grain Cu and the three related soil properties were not constant across space and there was great spatial non‐stationarity. Results also indicated that GWR could reveal the spatial variations of the relationships ignored by OLS and thus could be used to explain the local causes of Cu accumulation in rice grain. This study demonstrated the advantages of local spatial modeling techniques in modeling the accumulation of hazardous materials in soil–plant systems at regional scales.
Influence of Calcium Carbonate and Charcoal Applications on Organic Matter Storage in Silt‐Sized Aggregates Formed during a Microcosm Experiment
Authors: Kaiser Michael , Ghezzehei Teamrat A. , Kleber Markus , Myrold David D. , Berhe Asmeret Asefaw
Published: September 2014

Silt‐sized aggregates (2–53 μm) can store a high percentage of organic matter (OM) in agricultural soils. This study aimed to determine whether additions of charcoal and CaCO3may enhance the retention of organic C (OC) and total N (Nt) in silt‐sized aggregates. We used artificial soil mixtures without a silt component (89% sand, 10% clay, 1% OM) to emulate sandy soils with little natural structure. Charcoal and/or CaCO3were added, and the resulting mixtures were incubated for 16 wk in the dark. The newly formed silt‐sized fraction was separated and analyzed for OC and Ntconcentrations and characterized using FTIR and scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDS). Compared to the control treatment, CaCO3addition had no positive effects on C and N retention in the silt‐sized fraction (17–20 g kg−1OC, 0.15–0.17 g kg−1Nt) whereas the silt‐sized fraction from treatments with charcoal additions showed significantly higher OC and Ntconcentrations (50–56 g kg−1OC, 0.31–0.85 g kg−1Nt). Silt‐sized fractions from the charcoal treatments also showed a significant increase in the proportion of C=O groups. These initial results justify more detailed investigations into the improvement of the structure and nutrient retention of sandy soils by charcoal and CaCO3applications.
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.
Expression of p27Kip1 and E-cadherin in Head and Neck Squamous Cell Carcinoma of Indonesian Patients
Authors: E.I Auerkari , V Joewono , D.R Handjari , A.T Sarwono , A.W Suhartono , K Eto , M.A Ikeda
Published: September 2014

Cancer cells exhibit characteristic damage of DNA and its expression. The expression of the tumor suppressors E-cadherin and p27Kip1 has been tested on 57 head and neck squamous cell carcinomas (HNSCC) of Indonesian subjects. HNSCC tumor samples including both primary and (unrelated) nodal cases were obtained from the archives of Indonesian hospitals, in accordance with acknowledged ethical requirements. Only modest correlation was found between reduced expression of E-cadherin or p27Kip1 with increased malignancy of primary and nodal growth. The observed strong correlation regardless of malignancy between the expressed levels of E-cadherin and p27Kip1 suggests that also in combination these would not help to better predict the outcome of HNSCC.
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.
A Comparison of the Bacterial Microflora Found on the Surface of American
Kestrel and House Wren Eggs
Authors: Potte Beth A. , Hyde Emily J. , Pier Holly N. , Rutter Michael A. , Voss Margaret A.
Published: September 2014

It is generally accepted that avian eggs acquire a microflora during ovipositioning. The goal of this study was
to identify and compare the eggshell microflora of two avian species, House Wrens and American Kestrels. Differences in
the nesting habitats and incubation behavior of these species suggest that their eggshell microfloras also should differ.
Culture-dependent techniques were combined with sequencing of the 16S rRNA gene to identify bacteria in samples taken
from American Kestrel eggs during late incubation. These data were compared to previously collected data from House
Wren eggs. In both studies, bacteria were isolated from three different phyla, Actinobacteria, Firmicutes and Proteobacteria.
The eggshell microflora of Kestrels was dominated by bacteria in the Actinobacteria and Firmicutes phyla during late
incubation, whereas the eggshell microflora of House Wrens was dominated by bacteria in the Gamma-Proteobacteria
subphylum during pre- and late-incubation and bacteria within the Fimicutes phylum during early incubation. Actinobacteria
genera on House Wren and American Kestrel eggshells differed, but the prominent genera in the Gamma-
Proteobacteria and Firmicutes phyla, Pseudomonas and Staphylococcus, respectively, were similar between bird species.
Thus, our results suggest that the microflora of avian eggshells have both variable (i.e., phyla) and conserved (i.e., specific
genera) aspects of bacterial diversity.
Thermally activated building systems in context of increasing building energy efficiency
Authors: Stojanovic Branislav , Janevski Jelena , Mitkovic Petar , Stojanovic Milica , Ignjatovic Marko
Published: September 2014

One of the possible ways to provide heating to the building is to use
thermally activated building systems. This type of heating, besides providing
significant increase in building energy efficiency, allows using
low-temperature heating sources. In this paper, special attention is given to
opaque part of the building fa?ade with integrated thermally activated
building systems. Due to fact that this type of system strongly depends on
temperature of this construction-thermal element and type and thickness of
other materials of the fa?ade, influence of these parameters on energy
efficiency was analyzed in this paper. Since the simplest and most promising
way of using geothermal energy is to use it directly, for our analysis this
source of energy was selected. Building energy needs for heating were
obtained for real residential multi-family building in Serbia by using
EnergyPlus software. The building with all necessary input for simulation was
modeled in Google SketchUp with aid of Open Studio Plug-in. Obtained results
were compared with measured heating energy consumption. The results show that
thermally activated building systems represent good way to increase building
energy efficiency and that applying certain temperatures within this element,
low-energy house standard can be achieved.
Pumps used as turbines power recovery, energy efficiency, CFD analysis
Authors: Bogdanovic-Jovanovic Jasmina , Milenkovic Dragica , Svrkota Dragan , Bogdanovic Bozidar , Spasic Zivan
Published: September 2014

As the global demand for energy grows, numerous studies in the field of
energy efficiency are stimulated, and one of them is certainly the use of
pumps in turbine operating mode. In order to reduce time necessary to
determine pump characteristic in turbine operating mode problem was studied
by computational fluid dynamics approach. The paper describes various
problems faced during modeling (pump and turbine mode) and the approaches
used to resolve the problems. Since in the majority of applications, the
turbine is a pump running in reverse, many attempts have been made to predict
the turbine performance from the known pump performance, but only for best
efficiency point. This approach does not provide reliable data for the design
of the system with maximum energy efficiency and does not allow the
determination of the head for a wide range of flow rates. This paper presents
an example of centrifugal norm pump operating in both (pump and turbine)
regime and comparison of experimentally obtained results and computational
fluid dynamics simulations.
Serbian energy efficiency problems
Authors: Gvozdenac Dusan , Kljajic Miroslav , Gvozdenac-Urosevic Branka
Published: September 2014

The aim of this paper is to analyze and explore the most suitable energy
policy instruments for energy efficiency improvement in Serbia. The analysis
has been carried out with a focus on energy indicators for Serbia and EU27.
It encompasses a period of twenty-two years and is directed towards the
consideration of amendments that need to be made in the National Energy
Efficiency Policy. Despite constant attempts to improve and increase energy
efficiency and to expand utilization of renewable energy sources, it seems
that accomplished results are still very modest. The comparative analysis of
the situation in the area of energy efficiency in Serbia and in the EU takes
into consideration deficiencies in the energy policy in Serbia and proposed
measures for overcoming them. The Multiple Criteria Decision Analysis method
is used for analyzing the extent of key influences on success in the
implementation of energy efficiency policy in Serbia and also for the
interpretation of results. The analysis shows that identified energy policy
instruments are such that the success in their implementation will depend on
a reformed institutional approach. This method can be applied in any other
country.
Assessment of the turkey’s electric power policies in terms of sustainability
Authors: Atis Selcuk , Onat Nevzat , Guney Irfan
Published: September 2014

This study, using statistical data published by the Turkish Electricity
Transmission Company, analyzes key parameters such as installed capacity and
energy demand growth rates, investment plans and emission rates, taking into
consideration the expected increase in use through the year 2023. The results
of the analyses were compared to relevant data from around the world. The
weight of domestic - and especially renewable - resources in investment plans
for the next 10 years was discussed. Recommendations for an investment plan
to support sustainable development in Turkey are listed. Consequently, the
lack of investment in domestic and renewable energy projects decreases the
competitive power of Turkey vis-?-vis Organisation for Economic Co-Operation
and Development countries in terms of many parameters. For a sustainable
development, the country must make significant changes in its
foreign-dependent energy production policies. Any future policies must
encourage supplying local resources to meet the continuously increasing
demand. Qualifications for incentive mechanisms applied to investments in
renewable energy should be developed. The impact of the private sector on the
installation of new plants must also be increased by quickly completing the
privatization process.
Croatia's rural areas - renewable energy based electricity generation for isolated grids
Authors: Protic Sonja , Pasicko Robert
Published: September 2014

Several Western Balkan states face the consequences of the Yugoslavian war,
which left hometowns with dilapidated electricity grid connections, a high
average age of power plant capacities and low integration of renewable
energy sources, grid bottlenecks and a lack of competition. In order to
supply all households with electricity, UNDP Croatia did a research on
decentralized supply systems based on renewable energy sources.
Decentralized supply systems offer cheaper electricity connections and
provide faster support to rural development. This paper proposes a developed
methodology to financially compare isolated grid solutions that primarily
use renewable energies to an extension of the public electricity network to
small regions in Croatia. Isolated grid supply proves to be very often a
preferable option. Furthermore, it points out the lack of a reliable
evaluation of non-monetizable aspects and promotes a new interdisciplinary
approach.
Integrating the flexibility of the average Serbian consumer as a virtual storage option into the planning of energy systems
Authors: Batas-Bjelic Ilija , Skokljev Ivan , Puksec Tomislav , Krajacic Goran , Duic Neven
Published: September 2014

With the integration of more variable renewable energy, the need for storage
is growing. Rather than utility scale storage, smart grid technology (not
restricted, but mainly involving bidirectional communication between the
supply and demand side and dynamic pricing) enables flexible consumption to
be a virtual storage alternative for moderation of the production of
variable renewable energy sources on the micro grid level. A study,
motivated with energy loss allocation, electric demand and the legal
framework that is characteristic for the average Serbian household, was
performed using the HOMER software tool. The decision to shift or build
deferrable load rather than sell on site generated energy from variable
renewable energy sources to the grid was based on the consumer's net present
cost minimization. Based on decreasing the grid sales hours of the micro
grid system to the transmission grid from 3,498 to 2,009, it was shown that
the demand response could be included in long-term planning of the virtual
storage option. Demand responsive actions that could be interpreted as
storage investment costs were quantified to 1?2 per year in this article.
Effects of climate change on regional energy systems focussing on space heating and cooling: A case study of Austria
Authors: Hausl Stephan , Themessl Matthias , Gadocha Sabine , Schardinger Ingrid , Biberacher Markus , Castellazzi Bernhard , Gobiet Andreas
Published: September 2014

Climate change affects regions differently and therefore also climate change
effects on energy systems need to be analyzed region specific. The objective
of the study presented is to show and analyze these effects on regional
energy systems following a high spatial resolution approach. Three regional
climate scenarios are downscaled to a 1 km resolution and error corrected for
three different testing regions in Austria. These climate data are used to
analyze effects of climate change on heating and cooling demand until the
year 2050. Potentials of renewable energies such as solar thermal,
photovoltaic, ambient heat and biomass are also examined. In the last process
step the outcomes of the previous calculations are fed into two energy system
models, where energy system optimizations are executed, which provide
information concerning optimal setups and operations of future energy
systems. Due to changing climate strong changes for the energy demand
structure are noticed; lower heat demand in winter (between -7 and -15% until
2050) and - strongly differing between regions - higher cooling demand in
summer (up to +355%). Optimization results show that the composition of
energy supply carriers is barely affected by climate change, since other
developments such as refurbishment actions, price developments and regional
biomass availabilities are more influencing within this context.
Characteristics of basin inflows a statistical analysis for long-term/mid-term hydrothermal scheduling
Authors: Sutlovic Elis , Cujic-Coko Snjezana , Medic Ivan
Published: September 2014

The presented paper focuses on the characteristics of reservoir inflows and
the appropriate inflow model for long-term/mid-term hydrothermal scheduling.
The goal was to find the type of distribution that best fits the observed
series of monthly and weekly average inflows in most cases for a model which
considers the inflows as independent random variables without time
correlation. Also, the objective was to explore the correlation between the
inflows during time periods (for weekly and monthly intervals, respectively),
and to investigate whether the more complex model of reservoir inflow as a
dependent random variable is advisable for optimal long-term/mid-term
hydrothermal scheduling. Differences in the characteristics of monthly and
weekly inflows, which have been noticed during the analysis, are discussed.
Numerical results are presented.
Detailed analysis of the effect of the turbine and compressor isentropic efficiency on the thermal and exergy efficiency of a Brayton cycle
Authors: Zivic Marija , Galovic Antun , Virag Zdravko
Published: September 2014

Energy and exergy analysis of a Brayton cycle with an ideal gas is given. The
irreversibility of the adiabatic processes in turbine and compressor is taken
into account through their isentropic efficiencies. The net work per cycle,
the thermal efficiency and the two exergy efficiencies are expressed as
functions of the four dimensionless variables: the isentropic efficiencies of
turbine and compressor, the pressure ratio, and the temperature ratio. It is
shown that the maximal values of the net work per cycle, the thermal and the
exergy efficiency are achieved when the isentropic efficiencies and
temperature ratio are as high as possible, while the different values of
pressure ratio that maximize the net work per cycle, the thermal and the
exergy efficiencies exist. These pressure ratios increase with the increase
of the temperature ratio and the isentropic efficiency of compressor and
turbine. The increase of the turbine isentropic efficiency has a greater
impact on the increase of the net work per cycle and the thermal efficiency
of a Brayton cycle than the same increase of compressor isentropic
efficiency. Finally, two goal functions are proposed for thermodynamic
optimization of a Brayton cycle for given values of the temperature ratio and
the compressor and turbine isentropic efficiencies. The first maximizes the
sum of the net work per cycle and thermal efficiency while the second the net
work per cycle and exergy efficiency. In both cases the optimal pressure
ratio is closer to the pressure ratio that maximizes the net work per cycle.
Exergo-ecological evaluation of heat exchanger
Authors: Stanek Wojciech , Czarnowska Lucyna , Szczygiel Ireneusz , Rojczyk Marek
Published: September 2014

Thermodynamic optimization of thermal devices requires information about the
influence of operational and structural parameters on its behaviour. The
interconnections among parameters can be estimated by tools such as CFD,
experimental statistic of the deviceetc. Despite precise and comprehensive
results obtained by CFD, the time of computations is relatively long. This
disadvantage often cannot be accepted in case of optimization as well as
online control of thermal devices. As opposed to CFD the neural network or
regression is characterized by short computational time, but does not take
into account any physical phenomena occurring in the considered process. The
CFD model of heat exchanger was built using commercial package Fluent/Ansys.
The empirical model of heat exchanger has been assessed by regression and
neural networks based on the set of pseudo-measurements generated by the
exact CFD model. In the paper, the usage of the developed empirical model of
heat exchanger for the minimisation of TEC is presented. The
optimisationconcerns operational parameters of heat exchanger. The TEC
expresses the cumulative exergy consumption of non-renewable resources. The
minimization of the TEC is based on the objective function formulated by
Szargut. However, the authors extended the classical TEC by the introduction
of the exergy bonus theory proposed by Valero. The TEC objective function
fulfils the rules of life cycle analysis because it contains the investment
expenditures (measured by the cumulative exergy consumption of non-renewable
natural resources), the operation of devices and the final effects of
decommissioning the installation.
Lab-scale investigation of Middle-Bosnia coals to achieve high-efficient and clean combustion technology
Authors: Smajevic Izet , Hodzic Nihad , Kazagic Anes
Published: September 2014

This paper describes full lab-scale investigation of Middle-Bosnia coals
launched to support selection an appropriate combustion technology and to
support optimization of the boiler design. Tested mix of Middle-Bosnia brown
coals is projected coal for new co-generation power plant Kakanj Unit 8
(300-450 MWe), EP B&H electricity utility. The basic coal blend consisting of
the coals Kakanj: Breza: Zenica at approximate mass ratio of 70:20:10 is low
grade brown coal with very high percentage of ash - over 40%. Testing that
coal in circulated fluidized bed combustion technique, performed at
Ruhr-University Bohum and Doosan Lentjes GmbH, has shown its inconveniency
for fluidized bed combustion technology, primarily due to the agglomeration
problems. Tests of these coals in PFC (pulverized fuel combustion) technology
have been performed in referent laboratory at Faculty of Mechanical
Engineering of Sarajevo University, on a lab-scale PFC furnace, to provide
reliable data for further analysis. The PFC tests results are fitted well
with previously obtained results of the burning similar Bosnian coal blends
in the PFC dry bottom furnace technique. Combination of the coals shares, the
process temperature and the air combustion distribution for the lowest NOx
and SO2 emissions was found in this work, provided that combustion efficiency
and CO emissions are within very strict criteria, considering specific
settlement of lab-scale furnace. Sustainability assessment based on
calculation economic and environmental indicators, in combination with Low
Cost Planning method, is used for optimization the power plant design. The
results of the full lab-scale investigation will help in selection optimal
Boiler design, to achieve sustainable energy system with high-efficient and
clean combustion technology applied for given coals.
Sustainable port infrastructure, practical implementation of the green port concept
Authors: Pavlic Bostjan , Cepak Franka , Sucic Boris , Peckaj Marko , Kandus Bogomil
Published: September 2014

The overall idea and research interest related with the development of
sustainable port infrastructure evolved around the core requirements of
continuous reduction of negative environmental impacts without jeopardising
economic growth. The growth of trade activities and need for competitiveness
on the global market are forcing ports around the world to systematically and
continuously evaluate all possibilities for the optimisation and related
costs reduction. On the implementation level, the greatest challenge is how
to empower workers, who operate machines and work on the shop floor, to
achieve enduring performance improvements. Presented research work provides a
methodological approach for finding realistic solutions to the problem of the
future development challenges of seaports. The case study shown in this
research represents a practical application of the green port concept with
the emphasis on the overall energy efficiency improvement based on testing,
deployment and demonstration of energy efficient solutions. Additional
emphasis was placed on the state-of-the-art technologies and developing pilot
initiatives based on modern energy solutions designed to improve efficiency
in fuel consumption and emissions reduction in rubber tired gantry cranes.