bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining Conformance Treatment with Mobility Control Improves Oil Sweep Efficiency in Non-Cross Flow Heterogeneous Reservoirs
Authors: Imqam Abdulmohsin , Bai Baojun , Wei Mingzhen
Published: October 2015

On water flooding process, water preferential flow through high permeability, fractures, and large channels; cause a large amount of recycling of water without much benefit to oil production. Preformed particle gels (PPGs) have drawn more attention to reduce the fluid flow in these large opening features and to improve macroscopic oil efficiency. In spite of the successful applications of using PPGs in plugging such large features, there is still need to combine PPGs with other technology to produce more oil from the low permeable rich zones. The ultimate purpose of this study is to investigate the effectiveness of combining conformance control treatment using PPGs with mobility control using polymer to enhance oil recovery from both swept and un-swept oil zones. PPGs was injected into large permeability zones to reduce their permeability while polymer injected after gel to further increase oil recovery from the low permeability zones. Two separate parallel tubes packed with different sand grain sizes were designed to emulate the case when there is non-cross flow heterogenity between the low and the high permeability layers in the reservoir. Experiments were designed to examine the effect of permeability contrast ratio on the performance of coupling PPG and polymer to increase oil recovery. The results show a significant increase in oil recovery from both low and high permeability cores after performing polymer flooding right away after gel treatment. The oil recovery incremental was varied and strongly dependent on permeability contrast ratios. PPGs improved oil sweep efficiency significantly when the core permeability layers became more heterogeneous. Injection profile was improved after the PPG treatment, thus oil recovery from the low permeability cores was increased significantly.
Information and Analytical System for Prevention of Drilling Fluid Loss
Authors: Lind Yuliya B. , Samsykin Aleksei V. , Galeev Sergei R.
Published: October 2015

Drilling fluid losess seem to be the most widespread type of troubles during well construction on Bashkortostan oilfields. Elimination of a loss requires significant time and financial costs, so timely prevention of a loss by means of picking out appropriate drilling fluids for drilling perilous intervals is currently a promising task. And this is suggested to carry out on the base of field data on earlier drilled wells. The authors have developed an information and analytical system for prevention of drilling fluid losses, which includes a database on losses during wells construction at oilfields in Republic of Bashkortostan (RB), and a module of recommending drilling fluids basing on mathematical modeling and tracing of losses areas.
Geomechanical Model and Borehole Stability Prediction For One of the Fields of Perm Region
Authors: Predein Andrey , Klykov Pavel
Published: October 2015

Production of hard-to-recover reserves of Devonian system by drilling horizontal wells is one of the most promising areas of development of deposits in the Perm region. The main problems in the construction of wells with horizontal completion in the sediments of the Devonian system are related to the loss of stability of clay rocks ranging Timan terrigenous sediments. The destruction of clay rocks is a result of factors such as relieving current tectonic stresses and loss of stability of rocks due to the effect of propping microcracks under the influence of drilling mud. The paper presents the results of the determination of key parameters geomechanical model, calculated the wellbore stability, issued recommendations on the selection of the density of the drilling fluid and the most secure well path. Proposed component composition invert emulsion drilling fluids (IEF), designed to meet the real reservoir properties of unstable deposits of Devonian system. The mud is recommended for carrying out pilot projects for the construction of wells with horizontal completion in the sediments of the Devonian system.
Introduction of Gas Engines for Driving Gears of Pumping Machines
Authors: Yakin A. N.
Published: October 2015

Exploitation of oil sucker-rod pumps is one of the main mechanized methods of oil-mining. All machines are equipped with powerful electric engines, control stations, transformer substations, and overhead power lines. But we can do without this equipment, if in order to drive a pumping machine we use gas engine (GE) powered by associated petroleum gas (APG), obtained in the same well. It solves several problems at the same time. Firstly, associated petroleum gas is utilized.

APG is a mixture of hydrocarbon gas dissolved in oil and it's produced in the result of extraction and distillation. (20-500 m3 of gas per ton). In recent years, the public has paid close attention to the problem of utilization of associated gas, as well as increased penalties for inefficient use of valuable raw materials. From 60 billion m3 of associated gas, produced in the country each year, only half is utilized. The rest is simply flared, leading to half a million tons per year of harmful emissions into the atmosphere and tens of billions dollars of lost profit.

Secondly, at the same time it saves energy, because energy costs play a significant part in the cost of oil. Also it ensures uninterrupted oil production in small fields of remote single wells, where it's very expensive to form air lines. On some wells of "RITEK" the volume of associated gas is large enough. This makes the use of internal combustion engine for driving gears of pumping machines more cost-effective than the use of conventional electric drives.
The Algorithm of Integrated Productivity Forecast for Riphean Fractured Carbonate Reservoirs
Authors: Smolentcev Evgeniy , Kozyaev Andrew
Published: October 2015

This paper describes a method of predicting, riphean cavernous-fractured carbonate reservoir productivity integrating of seismic data, borehole imagers, well test survey and PLT. Apart from the description of the methodology itself, the paper contains some practical results of this implementing this approach based on a full-scale filtration model of one of East Siberia's oil fields.
Energy-efficient Natural and Associated Petroleum Gas Dehydration Technology with Composite Adsorbents
Authors: Akhtiamov A. , Konovalova K. , Kurochkin A.
Published: October 2015

Extracted natural and associated petroleum gases contain water vapor, amount of which is determined by pressure, temperature, gas composition and salinity degree of formation water.

The amount of water vapor in natural gas is regulated, because the moisture can condense in technological pipelines and vessels, forming liquid plugs, gas hydrates, as well as increase the corrosion rate of technological equipment, especially in the presence of acidic and corrosive substances (carbon dioxide, hydrogen sulfide, mercaptans, chlorine ions, salts).

There are several basic technologies used in oilfield conditions for natural gas dehydration: absorption dehydration, low temperature separation, membrane technology and adsorption dehydration.

Adsorption dehydration technology could be applied at all stages of gas production from the wellhead to the consumer: on the gas field and compressor stations treatment facilities, gas-processing on the gas processing plants and chemical complexes, as well as on the gas distribution stations and CNG stations. While technological scheme of gas dehydration unit fundamentally is not changed, differences relate only to layout solutions and auxiliary equipment.

In addition, in the oil and gas industry adsorption dehydration could be used for the gas field treatment of associated petroleum gas, for dehydration of fuel gases, as well as for dehydration of air and other process gases.

This paper presents new energy efficient technology of adsorption gas dehydration technology, which could be characterized by small weight and size of the final installation, small thermal energy and dehydrated gas consumption for regeneration of the adsorbent, and as a result, low capital and operating expenses, which allows to extend the limits of applicability of adsorption technology and to apply it for treatment of large volumes of gas.

Unit provides required degree of gas dehydration for the specified initial data and is characterized by a high level of industrial and environmental safety. Compared with the absorption dehydration, which is traditionally used for gas in fishing conditions developed installation is characterized by the decrease of capital expenses by 30%, operating expenses in 2-4 times, as well as decrease of the required area. Compared to other technologies (low temperature separation, membrane separation) reduced capital costs could reach 40%.
Introduction of Innovative Set for Real-Time Process Control Used for Watercut Prediction
Authors: Pirozhkov Maksim
Published: October 2015

Nowadays, the problem of enhanced oil recovery methods for already-run wells is literally a sticking point for oil and gas wells in Ugra region. Still the issue of development new oil and gas deposits, as well as the gradual replacement of routine labor with automatic systems and introduction of new innovative technologies is of great importance for oil companies throughout the country. Lets try to imagine how can possibly the abovementioned interdependent problems can be solved by using modern science and technology base. For all the oil companies the question on adequate water cut monitoring and control remains as the paramount one. The methods, using pre-separation of the product to gas and the water-oil emulsion, followed by measuring their flow through gauges are outdated. One of the latest technologies of measurement the oil, gas and water flow without phase separation is multiphase well testing. In many cases, they give a more accurate image of flow parameters under dynamic conditions, and are particularly useful for heavy oils and gas condensates where conventional measurement methods are not suitable because of the difficulty in the phase separation. For decades oil and gas industry tried numerous attempts to find a solution to devise a system that could measure the flow rates of well fluids, without dividing them into phases, without using moving parts and controlling the process. However no one has been able to propose a procedure of continuous monitoring, which among other things would make analysis parameters of the working system with well performance prediction and real-time information on well performance delivery.
Variation Among Maize Hybrids in Response to High Vapor Pressure Deficit at High Temperatures
Authors: Shekoofa Avat , Sinclair Thomas R. , Messina Carlos D. , Cooper Mark
Published: October 2015

Temperature and vapor pressure deficit (VPD) are two important environmental factors influencing stomatal conductance and transpiration. A limited transpiration rate (TRlim) trait expressed under high VPD has been shown to offer an approach to increase crop yield in water‐limited areas. The benefit of the TRlim trait is that it lowers the effective VPD under which plants lose water and so conserves soil water to support crop growth for use during drought periods later in the growing season. Previous studies at moderate temperatures (32°C and lower) identified 12 maize (Zea mays L.) hybrids that express the TRlim trait. A critical question is whether the TRlim trait is also expressed by these hybrids under temperatures up to 38°C, which are relevant in environments where maize may be grown. Five hybrids failed to express the TRlim trait at 38°C but seven hybrids had sustained expression of the trait at 38°C. The loss of expression of the TRlim response in the five hybrids was found to occur in the very narrow range of temperature increase from 36 to 38°C. The genetic differences in water use among these maize hybrids could be useful in selecting hybrids that are especially well adapted for temperature conditions in a targeted production area.
The content and UV-Vis absorbances of bog peat organic matter fractions (Divcivare, Serbia)
Authors: Petrovic Petar , Radmanovic Svjetlana , Djordjevic Aleksandar , Zivotic Ljubomir , Lalevic Blazo
Published: October 2015

This paper presents peat soil organic matter characteristics at Divcibare
Mountain (950 m a.s.l, mountain climate). Excessive wetting is caused by
groundwater and floods, and plant litter originates from hydrophilic
vegetation. An investigation was aimed at determining the correlation between
organic matter characteristics (humification degree, stability and
bioavailability) with factors of soil formation and the most important
physico-chemical characteristics of peat. Peat is mild acid and has a low
base saturation. The content of organic matter is higher than 60% at depth of
40?80 cm, and higher than 40% at depths of 0?40 and 80?105 cm, respectively.
Investigated peat had sapric characteristics. A content of humic acids in
total organic matter indicates its unequal humification degree within
profile, moderate to high at depth of 0?40 cm, low at 40?80-cm depth, and
very low beneath 80 cm. A value of Ch/Cf ratio indicates high humus stability
up to 80 cm where it has humate-type humus, while below 80 cm humus is the
humatefulvate type. A low content of fractions separated with 0.1N cold
H2SO4, and cold and hot water, points out a low bioavailability of organic
matter through whole soil profile. UV-Vis indices indicate a low humification
degree of humic acids (increased to 80-cm depth), and a very low humification
degree of fulvic acids (variable, the highest at 60?80-cm depth). Overall
results indicate that particle size of mineral fraction, soil reaction, and
cation exchange capacity had no significant impact on organic matter
characteristics. Soil moisture content, that is alterations of
oxido-reductive conditions throughout soil profile had the crucial impact on
peat organic matter characteristics.
Polymorphism of Pramenka sheep hemoglobin in Central Bosnia
Authors: Vazic Bozo , Rogic Biljana , Drinic Milanka , Savic Nebojsa
Published: October 2015

The study of the hemoglobin polymorphism was performed on blood samples,
taken from areas inhabited by Pramenka sheep in Central Bosnia: the area of
the mountain Vlasic, the upper flow of the river Vrbas and Kupres plateau.
Dupska pramenka sheep inhabits the mountain Vlasic and the areas of
surrounding municipalities. Privorska pramenka sheep inhabits the area around
the upper flow of the river Vrbas and the mountain Vranica and Kupreska
pramenka sheep inhabits Kupres plateau. HbA gene frequency was 0.31 and HbB
gene frequency was 0.69 for Dupska pramenka sheep. Privorska pramenka sheep
had a frequency of 0.33 for the HbA gene, and 0.67 for the HbB gene, in its
population. Kupreska pramenka sheep had the lowest frequency of the HbA gene,
(0.30), and therefore the maximum frequency of the HbB gene. Hemoglobin
genotype frequencies for all investigated types of Pramenka sheep breed are
in equilibrium. Investigated types of Pramenka sheep breed inhabit areas
adjacent to each other. They are phenotypically quite similar and have a
similar frequency of genotype polymorphism of hemoglobin. The difference
between them is not statistically significant.
Effect of nitroxin and humic acid on yield and yield components of faba bean
Authors: Kholdi Abolfazl , Sedaghathoor Shahram , Poursafarali Eshagh
Published: October 2015

Quality and quantity improvement of crops using organic matter and low-cost
method in the field is very important. Bio-fertilizer nitroxin and humic
acid can increase root and shoot biomass through improved intake of
nutrition and they can lead to quality and quantity improvement of product.
An experiment was carried out as a completely randomized block design with 4
treatments to study the effect of nitroxin and humic acid on faba bean
(Vicia faba L.) traits. Trial treatments included control, nitroxin, humic
acid and nitroxin + humic acid. Analysis of variance showed that the effect
of combination of nitroxin + humic acid was significant (p< 1%) on some
traits such as stem height and yield of faba bean. The highest yield (2,315
kg ha-1) was obtained under nitroxin + humic acid treatment.
The possibility of crop cultivation and utilization of edible gum from herb (Dorema ammoniacum D. Don) in dryland farming
Authors: Gholami Barat , Faravani Mahdi
Published: October 2015

Gum ammoniacum (Dorema ammoniacum D. Don) is one of the most important food,
industrial and medicinal plants of Iran which is mainly distributed in
semi-arid and desert areas. It is endangered due to superfluous and
unsustainable harvesting methods. The objective of this study was to evaluate
the possibility of crop cultivation in terms of dryland farming and the best
operation method for collecting gum resin. For this purpose, the effects of
different scarification methods (traditional, concave and staircase) and
cut-off frequencies (5, 10 and 13 times) on gum yield of the five-year-old
plants were studied at Toroq farm in Mashhad. The treatments were studied
under a split plot structure in time experiment which was arranged in a
completely randomized design with three replications. The rate of the root
gum production and the rate of plant survival in the years after the
withdrawal were measured, and finally the data were analyzed. Results showed
no significant differences among cutting methods at p<0.05. The yield of gum
was affected by times of harvesting and the highest yield was observed
(p<0.01) in 13 cut-off times with 31.67 g/plant. The lowest gum yields were
seen in 5 cut-off times with 5.84 g/plant. The traditional cutting method
destroyed crown buds and caused the death of the plant (p<0.01). Reasonable
gum yields and plant regeneration rates were obtained with the use of stairs
method which is an easy method to be applied by the farmers or beneficiaries.
Combination Therapy Reverses Hyperglycemia in NOD Mice With Established Type 1 Diabetes
Authors: Xue Song , Posgai Amanda , Wasserfall Clive , Myhr Courtney , Campbell-Thompson Martha , Mathews Clayton E. , Brusko Todd , Rabinovitch Alex , Savinov Alexei , Battaglia Manuela , Schatz Desmond , Haller Michael , Atkinson Mark A.
Published: October 2015

An increasing number of therapies have proven effective at reversing hyperglycemia in the nonobese diabetic (NOD) mouse model of type 1 diabetes (T1D), yet situations of successful translation to human T1D are limited. This may be partly due to evaluating the effect of treating immediately at diagnosis in mice, which may not be reflective of the advanced disease state in humans at disease onset. In this study, we treated NOD mice with new-onset as well as established disease using various combinations of four drugs: antithymocyte globulin (ATG), granulocyte-colony stimulating factor (G-CSF), a dipeptidyl peptidase IV inhibitor (DPP-4i), and a proton pump inhibitor (PPI). Therapy with all four drugs induced remission in 83% of new-onset mice and, remarkably, in 50% of NOD mice with established disease. Also noteworthy, disease remission occurred irrespective of initial blood glucose values and mechanistically was characterized by enhanced immunoregulation involving alterations in CD4+ T cells, CD8+ T cells, and natural killer cells. This combination therapy also allowed for effective treatment at reduced drug doses (compared with effective monotherapy), thereby minimizing potential adverse effects while retaining efficacy. This combination of approved drugs demonstrates a novel ability to reverse T1D, thereby warranting translational consideration.
β-Cell MicroRNAs: Small but Powerful
Authors: Filios Stephen R. , Shalev Anath
Published: October 2015

Noncoding RNA and especially microRNAs (miRs) have emerged as important regulators of key processes in cell biology, including development, differentiation, and survival. Currently, over 2,500 mature miRs have been reported in humans, and considering that each miR has multiple targets, the number of genes and pathways potentially affected is huge. Not surprisingly, many miRs have also been implicated in diabetes, and more recently, some have been discovered to play important roles in the pancreatic islet, including β-cell function, proliferation, and survival. The goal of this Perspective is to offer an overview of this rapidly evolving field and the miRs involved, reveal novel networks of β-cell miR signaling, and provide an outlook of the opportunities and challenges ahead.
Fuzzy Cellular Automata Models for Crowd Movement Dynamics at Signalized Pedestrian Crossings
Authors: Chai Chen , Wong Yiik Diew , Er Meng Joo , Gwee Evan Tat Meng
Published: October 2015

Crowd movement dynamics at a signalized pedestrian crossing constitutes a complex system affected by many factors. Existing crowd simulation models seldom consider cognition and decision making of individual pedestrians. In this study, a fuzzy cellular automata (FCA) model was developed to simulate pedestrian movements at crowded signalized pedestrian crossings that incorporated pedestrian decision-making processes. The proposed FCA model incorporated fuzzy logic into a conventional cellular automata (CA) model. In contrast to existing models and applications, the proposed FCA model used fuzzy sets and membership functions to simulate individuals’ decision making process. Four fuzzy sets were applied for each decision: stop or go (stop–go) decision, moving direction, velocity change, and congregation. Membership functions of each input factor as well as weight factors of each fuzzy set at different movement zones were calibrated on the basis of field observations. Model performance was assessed by comparisons of trajectories between estimation and observation, interactions with conflicting vehicles and pedestrians, and congregation phenomena. Through a simulation experiment and comparison with existing approaches, simulation results show that the FCA model can well replicate crowd movement dynamics in real-world pedestrian crossings.
Microscopic Simulation of Synchronized Flow in Oversaturated City Traffic
Authors: Hermanns Gerhard , Hemmerle Peter , Rehborn Hubert , Koller Micha , Kerner Boris S. , Schreckenberg Michael
Published: October 2015

Synchronized flow has been found recently in studies of empirical GPS probe-vehicle data collected in oversaturated city traffic. In this paper, results of simulations with a three-phase microscopic model from Kerner and Klenov are presented. These results show features of synchronized flow. The effect of the driver's speed adaptation was found to play the key role in understanding the emergence of synchronized flow in over-saturated city traffic. The physical meaning of the speed adaptation effect in oversaturated city traffic was explained, and the influence of the speed adaptation effect on the average speed and travel time in oversaturated city traffic was investigated.
Modern Air Combat Developments and Their Influence on Neck and Back Pain in F-16 Pilots
Authors: Thoolen Stijn J. J. , van den Oord Marieke H. A. H.
Published: October 2015

INTRODUCTION: Neck and back pain in fighter pilots remains a serious occupational problem. We hypothesized that recent advances such as the joint helmet mounted cueing system (JHMCS) in modern air combat might contribute to the development of spinal complaints in F-16 pilots.METHODS:
Surveyed were 59 F-16 pilots of the Royal Netherlands Air Force who were compared to 49 F-16 pilots who filled in a similar questionnaire in 2007. The prevalence of neck and back pain, work situations, and capacity of the pilot were analyzed.RESULTS: The self-reported 1-yr prevalence
of regular or continuous neck and lower back pain in 2014 were 22% and 31%, respectively, compared to both being 12% in 2007. Age, military flying experience, total number of flying hours, flying hours on the F-16, and total number of hours flown with night vision goggles (NVG) were significantly
higher in 2014. In 2014, 95% flew with JHMCS, compared to 0% in 2007. Flying with JHMCS (88%), NVG (88%), type of flight (63%), and sitting posture (50%) were the most reported causes of flight-related neck pain. Sitting posture (89%), duration of flight (56%), and seat (44%) were among the
reported causes of back pain.DISCUSSION: The increasing trend of neck and lower back pain might be caused by multiple changes in both the work situation and capacity of the pilots since 2007. Future innovations will increase the load on the pilot’s spine. To successfully address
their spinal problems in the future, fighter pilots must be monitored continuously.Thoolen SJJ, van den Oord MHAH. Modern air combat developments and their influence on neck and back pain in F-16 pilots. Aerosp Med Hum Perform. 2015; 86(11):936–941.
Bias from Differential Exposure Measurement Error in a Study of Flight Attendants
Authors: Johnson Candice Y. , Grajewski Barbara
Published: October 2015

BACKGROUND: Self-reported occupational exposures are often used in epidemiological studies when actual exposure measurements are unavailable, which could cause measurement error and bias study results. This study provides a numeric example of this potential bias.METHODS:
A study of block hours and preterm birth was used as an illustrative example. This study included 577 flight attendants, ages 18-45 yr, who gave birth to a term (37 or greater gestational weeks) or preterm (20-36 gestational weeks) infant between 1992 and 1996. Flight attendants self-reported
the number of block hours flown during the first trimester of pregnancy; the number of block hours flown during the first trimester of pregnancy was also calculated from airline records. No adjustment for confounding was performed for this illustrative example.RESULTS: Although
flight attendants having term and preterm births self-reported similar hours worked during the first trimester (median 213 vs. 215 block hours), airline records showed that flight attendants having term births worked more hours than those having preterm births (median 146 vs. 104 block hours).
Using self-reported block hours, there was no association between block hours and preterm birth; when using airline records, an inverse association was observed.DISCUSSION: In this example, differential measurement error from use of self-reported block hours obscured an inverse
association apparent when using airline records, demonstrating the importance of accurate exposure assessment for identifying occupational risk factors for health outcomes.Johnson CY, Grajewski B. Bias from differential exposure measurement error in a study of flight attendants.
Aerosp Med Hum Perform. 2015; 86(11):990–993.
Development and Validation of the Cognition Test Battery for Spaceflight
Authors: Basner Mathias , Savitt Adam , Moore Tyler M. , Port Allison M. , McGuire Sarah , Ecker Adrian J. , Nasrini Jad , Mollicone Daniel J. , Mott Christopher M. , McCann Thom , Dinges David F. , Gur Ruben C.
Published: October 2015

BACKGROUND: Sustained high-level cognitive performance is of paramount importance for the success of space missions, which involve environmental, physiological, and psychological stressors that may affect brain functions. Despite subjective symptom reports of cognitive fluctuations
in spaceflight, the nature of neurobehavioral functioning in space has not been clarified.METHODS: We developed a computerized cognitive test battery (Cognition) that has sensitivity to multiple cognitive domains and was specifically designed for the high-performing astronaut
population. Cognition consists of 15 unique forms of 10 neuropsychological tests that cover a range of cognitive domains, including emotion processing, spatial orientation, and risk decision making. Cognition is based on tests known to engage specific brain regions as evidenced
by functional neuroimaging. Here we describe the first normative and acute total sleep deprivation data on the Cognition test battery as well as several efforts underway to establish the validity, sensitivity, feasibility, and acceptability of Cognition.RESULTS: Practice
effects and test-retest variability differed substantially between the 10 Cognition tests, illustrating the importance of normative data that both reflect practice effects and differences in stimulus set difficulty in the population of interest. After one night without sleep, medium
to large effect sizes were observed for 3 of the 10 tests addressing vigilant attention (Cohen’s d = 1.00), cognitive throughput (d = 0.68), and abstract reasoning (d = 0.65).CONCLUSIONS: In addition to providing neuroimaging-based novel information on the effects of spaceflight
on a range of cognitive functions, Cognition will facilitate comparing the effects of ground-based analogues to spaceflight, increase consistency across projects, and thus enable meta-analyses.Basner M, Savitt A, Moore TM, Port AM, McGuire S, Ecker AJ, Nasrini J, Mollicone DJ, Mott
CM, McCann T, Dinges DF, Gur RC. Development and validation of the Cognition test battery for spaceflight. Aerosp Med Hum Perform. 2015; 86(11):942–952.
The influence of the curing conditions of concrete on durability after freeze-thaw accelerated testing
Authors: Al-Assadi G. , Casati M. J. , Gálvez J. C. , Fernández J. , Aparicio S.
Published: October 2015

This work relates the curing conditions of concrete with the damage caused by rapid freeze-thaw cycles (ASTM C 666). The “potential” durability of concrete after testing is also studied. In countries with a continental climate, the curing of concrete in summer is performed under high-temperature and low-humidity conditions, and during the winter the concrete undergoes freezing and thawing. This paper shows the experimental results of the behaviour of concrete specimens cured under climatic summer conditions and then subjected to freeze-thaw cycles. Curing of the specimens includes conditions of good and bad practice in relation to wetting and protection of the concrete. Mechanical properties, cement hydration, volume and pore sizes, oxygen permeability, chloride diffusion and water penetration under pressure tests of the concrete are assessed. These tests were performed before and after the application of the freeze-thaw cycles. Statistical analysis of the correlation among variables is also included.
Population genetic structure and demographic history of Aphanius fasciatus (Cyprinodontidae: Cyprinodontiformes) from hypersaline habitats in the eastern Adriatic
Authors: Buj Ivana , Miočić-Stošić Jure , Marčić Zoran , Mustafić Perica , Zanella Davor , Mrakovčić Milorad , Mihinjač Tanja , Ćaleta Marko
Published: October 2015

In order to investigate the phylogeography and population genetic structure of the South European toothcarp (Aphanius fasciatus), we analysed gene sequences of two mitochondrial markers (cytochrome b and mtDNA control region) in samples from eight localities along the eastern Adriatic coast and combined them with sequences from other Mediterranean localities. Since the South European toothcarp primarily inhabits hypersaline water bodies, it is a good model species for understanding patterns of colonization and dispersal of species adapted to variable conditions. The eastern Adriatic populations are separated into two groups of genetically related populations. The Northern group contains the populations from Sečovlje, Pag, Dinjiška, Nin and Pantan, whereas the Southern group contains the populations from Ston, Ulcinj and Narta. The majority of divergence events date back to the Pleistocene epoch and it is likely that sea level changes during glacial cycles played a significant role in shaping the recent genetic structure of this species. Our results imply pronounced intraspecific structuring of this species, whereas great environmental variations resulted in a smaller intrapopulational genetic diversity of A. fasciatus than seen in other Mediterranean fishes.
e-REAL: Enhanced Reality Lab
Authors: Salvetti Fernando , Bertagni Barbara
Published: October 2015

e-REAL - enhanced reality lab - is a fully-immersive and multitasking environment, designed to experience challenging situations in a group setting, engaging all participants simultaneously on different levels: with peers, thematic experts and learning facilitators, both on site and remotely. e-REAL is a lab based on visual thinking and knowledge visualization, facilitated by enhanced (or augmented) reality tools. It is a highly interactive and face-to-face lab that promotes proactive data and information research (everything is available, but learners have to actively look for it) - allowing knowledge sharing with remote teams and integrating training on soft skills with those that are technical and specialized.
Dynamic Stress Dissipated Energy Rating of Materials with Maxwell Rheological Behavior
Authors: Bratu Polidor
Published: October 2015

This paper presents dynamic analysis of rheological behavior of materials modeled as a body under stationary harmonic dynamic action.Excitation force is inertial, because of rotation of eccentric mass, applied directly to the Maxwell rheological body.Based on theoretical and experimental results are highlighted functions for defining both the energy dissipated as hysteresis loops in physical conditions of linear behavior of the components of the Maxwell model.In this context are represented the representative sets of curves that outlines the progress of dissipation made in relation with the dynamic system parameters.
On the Use of Higher-Order Frequencies in Crack Identification in Columns Subjected to Important Tip Mass
Authors: Gillich Gilbert Rainer , Muntean Florian , Nitescu Codrin Nistor , Iancu Vasile , Praisach Zeno Iosif , Korka Zoltan Iosif
Published: October 2015

The paper present a novel non-destructive evaluation method designed to assess damage in structural elements subjected to important axial loads, as columns are. In the prior research a reliable damage detection method was developed for beams subjected to own mass, that consider the relation existing between the energy stored in the beam in certain vibration modes and the related natural frequencies. First we found the mathematical relations expressing the healthy pillar mode shapes and frequencies with respect to the top mass. Afterward, by means of FEM, we derived the natural frequencies for the numerous damage cases, in order to define the frequency shift curves. Analogous to the case of beams, the damage location is characterized by patterns that are derived from the mode shape curvatures square of the healthy beam. The damage location becomes an inverse problem while the damage position is found by interpreting frequency measurements made on the healthy and damaged beam.
The Damping Study for Dammar Composites Reinforced with Natural Fibers
Authors: Bolcu Dumitru , Stănescu Marius Marinel , Miriţoiu Cosmin Mihai , Burada Cristian Oliviu
Published: October 2015

In this paper we have studied the vibration damping for composite bars made by dammar based natural resin, the reinforcement being made by flax, cotton, silk and hemp fibers. There were made rectangular section samples (5x10 mm) with 220 mm length. The bars were clamped, the free length being 100 mm, 120 mm, 140 mm, 160 mm and 180 mm. For each bar, the free vibrations made by an initial deformation, obtained by inserting an external force in the free end, were recorded. In each case, the measured vibration was under-damped.
Vibration Analysis of Insufficiently Repaired Well Pump - A Case Study
Authors: Jovanović Dragan , Jovanović Milena , Raos Miomir , Živković Nenad , Stanković Milena , Protić Milan
Published: October 2015

Vibration analysis of the repaired well pump is to determine whether vibrations occur due to an insufficient pump repair or due to some new malfunction that happened after the repair. This paper presents vibration analysis of well pump as well as the applied corrections in order to lower the vibration levels. Vibration measurement of well pump is conducted on measurement points defined by standard ISO 10816-1.
Experimental and Theoretic Viscoelastic Behavior of Functional Spinal Unit, In Stress Relaxation Test
Authors: Stoia Dan Ioan , Vigaru Cosmina , Rusu Lucian
Published: October 2015

The objective of the study was to design a simulation model that approximates the real viscoelastic behavior of spinal units in stress relaxation tests. The spinal units were sampled from porcine and used in fresh condition, without frizzing or drying. The mechanical tests were conducted on Mecmesin5i testing machine using the appropriate devices for compression tests. On the other hand, using Maxwell constitutive equation for relaxation, a Simulink model was created. At the end, the relaxation curve derived from the simulation model was draw next to experimental obtained data in order to represent the fitting.
Viscoelastic Behavior Simulation of Cortical Bone Tissues Using Burgers Rheological Model
Authors: Perescu Alexandru , Suciu Oana , Neamțu Adela , Nes Cristian Sorin , Bereteu Liviu
Published: October 2015

The elastic properties of cortical bone tissue and other types of bone have been determined by the classical methods such as tensile stress and shearing stress. In recent years, by nanoindentation method, it has developed techniques for measuring the viscoelastic properties of bone tissues. In the same time, they show effects the dependent on time due to loading. The time dependent behavior of such viscoelastic materials may be described by constitutive equations whose variables are stress, deformation and time. These equations may be expressed by means of rheological models. Furthermore, bone tissues present both the phenomenon of creep and relaxation, indicating that they have a rheological behavior. In this paper viscoelastic behavior of bone is simulated numerically, and analyzed in Simulink, using Burgers rheological model.
Influence of Carpal Tunnel Syndrome Induced by Vibratory Actions upon Fingers Mobility
Authors: Cotoros Diana , Baritz Mihaela , Stanciu Anca Elena
Published: October 2015

Carpal Tunnel Syndrome (CTS) is a kind of neuropathy developed due to irritated tendons that may affect the passageway made of ligaments and bones, located at the wrist (base of palm). People affected by CTS develop symptoms such as pain in the carpal area, sometimes reflected along the entire arm, swelling, difficulties in finger motions, reduced range of motion due to pressure upon the median nerve. The present paper performs a case study upon a female subject affected by CTS. The subject is investigated and then guided to perform some exercises using the software attached to the used equipment (sensory gloves), over a controlled period of time with rehabilitation purposes.
Assessment of the Occupational Effects of Vibrations on the Human Body
Authors: Barbu Daniela Mariana , Cotoros Diana Laura
Published: October 2015

Vibration is a complex mechanical oscillation of solids that can be transmitted directly to the body. By exposing the body to vibration, tissues begin to move from their natural position. In the work setting, there are basically three types of vibration that are medical significant: whole body vibration, segmental vibration and human resonance. When the body comes directly in contact with mechanical vibration, a direct adverse physiological and physical effect occurs on that body. This type of effects interferes with work efficiency and productivity of labor and, in some situations, can put the workers at risk for injury. In ergonomics, any factor that has the potential to impair the worker’s function may be a significant issue and therefore must be eliminated or reduced to the greatest extent possible. In this context, the paper presents an assessment of the effects that vibrations may have on the human body and find ways to prevent or eliminate them. In order to strengthen theoretical information, a case study is presented.
Generalization of the Krylov-Bogoliubov Method for Nonlinear Oscillators
Authors: Cveticanin Livija
Published: October 2015

In this paper the Krylov-Bogoliubov method for solving nonlinear oscillators is considered. Based on the original method, developed for the oscillator with small nonlinearity, a generalization is made to oscillators with strong nonlinearity. After rewriting the equation into two first order differential equations, the averaging procedure is introduced. Truly nonlinear differential equations are investigated where the linear term does not exist nor the linearization of the equation is possible. Solution is assumed in the form of the Ateb-function. After averaging the approximate solution for the oscillator is obtained. A numerical example is tested. It is shown that the difference between the analytical approximate solution and the exact numerical one is negligible.
On the Open Problem: An Optimal Analytical Solution for Duffing Oscillator
Authors: Marinca Vasile , Ene Remus Daniel , Ghita Eugen Ioan
Published: October 2015

Based on the Optimal Homotopy Perturbation Method (OHPM), an analytical approximate solution to Duffing’s nonlinear oscillator problem is obtained. Using renormalization group method, Kirkinis [1] obtained an asymptotic solution to Duffing’s nonlinear oscillation problem. Kirkinis then asked if his asymptotic solution is optimal. In this paper, a negative answer to this open problem is given by means of OHPM.
Dispersion of Multi-Walled Carbon Nanotubes in Portland Cement Concrete Using Ultra-Sonication and Polycarboxylic Based Superplasticizer
Authors: Yousefi Ali , Muhamad Bunnori Norazura , Khavarian Mehrnoush , Majid Taksiah A.
Published: October 2015

The potential properties of carbon nanotube-cement based materials strongly depend on the dispersion of carbon nanotubes (CNTs) within the cement matrix and the bonding between CNTs and the hydrated cement. The homogeneous dispersion of CNTs in the cement matrix yet is one of the main challenges due to strong van der Waals forces between nanotubes. In this study, a polycarboxylic ether based superplasticizer and ultra-sonication technique was used for dispersion of multi-walled carbon nanotubes (MWCNTs). Portland cement concrete specimens with different concentrations of MWCNTs (0.04 and 0.1 % by the weight of cement), with and without the presence of superplasticizer were investigated. Compressive strength test results revealed a significant improvement in mechanical properties of sample containing 0.1 % MWCNTs and 0.2 % superplasticizer. Moreover, field emission scanning electron microscopy (FESEM) images of fractured surfaces of hardened specimens showed a good dispersion of MWCNTs within the cement matrix. This method was developed to facilitate the uniform dispersion of MWCNTs in the cementitious concrete for better reinforcement in nanoscale and mechanical properties enhancement by transfer of load between the nanotubes and matrix.
Drying Shrinkage of Fly Ash Mortar Mixed with Seawater
Authors: Bautista John Wilmer , Crockett John Benedict , Liu Beatrice Ann , Obra Timothy John , Roxas Cheryl Lyne
Published: October 2015

Drying shrinkage in mortar produces cracks and micro-cracks which affect the durability of a structure. The effects of seawater as a substitute to freshwater and fly ash as a partial replacement for cement were investigated in this study in order to address the predicted water shortage by 2025 and the increasing carbon footprint from carbon dioxide emissions worldwide. Moreover, these materials are also more economical alternatives to freshwater and cement. Rectangular prism specimens with varying fly ash content (10%, 15%, 20%, 25%, and 30%) were cast to measure the drying shrinkage in mortar while 50-mm cube mortar specimens were prepared to determine the compressive strength. This study investigated whether the addition of fly ash and seawater reduced the drying shrinkage of mortar. From the results, it was found that mortar specimens with 20% fly ash replacement achieved the highest early and late strengths. Partial substitution of fly ash would result to shrinkage in mortar while substitution of seawater to freshwater counteracts the effects of fly ash, thus producing less shrinkage. Fly ash content between 20%-25% combined with seawater produces the least shrinkage value without compromising the minimum required compressive strength.
Experimental Study on the Effect of Macroroughness on Tsunami Flow and Loading of Building
Authors: Moon Wei Chek , Chiew Lerk Qing , Cheong Kah Win , Tee Yi Cong , Chun Jan Bong , Lau Tze Liang
Published: October 2015

This study experimentally investigated the effect of nearby buildings, termed macroroughness on the tsunami loading. The hydraulic experiment was conducted in a 1 m x 1 m with 40 m long wave flume at a scale of 1:100. Nominal wave height of 40 mm was simulated in this study. Both the building model and the macroroughness elements consisted of 66 mm high solid blocks. Wave pressures exerted on frontal and back faces of the building model were discussed in detail in this paper. Experimental results showed that the macroroughness elements had a significant impact on tsunami loading in the inundation zone. Sheltering effect was exhibited by the seaward macroroughness elements, showing significant reduction in the front face pressures. With the presence of the landward macroroughness elements, the wave pressures at the back face of the building model increased significantly at the initial impact.
Influence of Crumb Rubber on Impact Energy of Steel Fiber Concrete Beams
Authors: Noaman Ahmed Tareq , Abu Bakar Badorul Hisham , Akil Hazizan Md.
Published: October 2015

This paper presents the impact energy of steel fiber concrete beams at first crack and failure with different replacement ratios of crumb rubber. The test was carried out using simple low velocity drop weight test rig for both normal concrete (NC) and steel fiber concrete (SFC). The crumb rubber with particle size of 1 – 2 mm was added with replacement ratios of 5%, 15%, and 25% by volume of fine aggregate. Six batches consisting of 6 beams (100x100x500 mm) containing 0.5% of hooked end steel fibers were tested under impact load in accordance with ACI Committee 544. The specimens were tested at the age 90 days after curing in water. The results show a reduction in the compressive strength for both NC and SFC with the incorporation of crumb rubber with greater reduction at higher crumb rubber content. However, the measured impact energy for both NC and SFC was foundincreasing with the crumb rubber replacement.
Influence of Initial Silica Modulus of Na2SiO3 on the Compressive Strength of Alkali Activated Ultrafine Palm Oil Fuel Ash Based Mortar
Authors: Elbasir Otman M.M. , Megat Johari Megat Azmi , Ahmad Zainal Arifin
Published: October 2015

The influence of silica modulus (Ms) on the compressive strength of alkali activated ultrafine palm oil fuel ash based mortar has been investigated. Two alkali activated mortar mixtures, S1 and S2 were prepared using sodium silicate (Na2SiO3) with initial silica moduli, Ms of 3.3 and 2, respectively. The Na2SiO3 was used in combination with sodium hydroxide (NaOH) with NaOH concentration of 10 M. The results indicate that the S2 mortar mixture has higher strength than the S1 mortar mixture at all testing ages, with 28 day strength of 27.18 MPa and 32.8 MPa recorded by S1 and S2 mortar mixture, respectively. Hence, lower Ms leads to higher compressive strength. The higher compressive strength of S2 is corroborated by the formation of more C-S-H as implied by the Fourier Transform Infra-red (FTIR) spectra analysis.