bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology Focus: Offshore Drilling and Completion (April 2015)
Authors: Rylance Martin
Published: February 2016

Technology Focus

To the casual observer of completions and hydraulic fracturing, it might appear that multifractured horizontal wells are a relatively recent concept that materialized just as we required them for unconventionals. However, those in the know will recognize that the marriage of fracturing and stimulation operations with horizontals was forged almost 30 years ago in an environment far removed from unconventionals.

In fact, it was the high-cost, limited-well, offshore environment that drove the need for higher production rates from single wellbores and indeed from horizontals and high-angle wells because of the limitations imposed by platform footprint and achievable step-out geometry. Substantial progress in multifractured horizontal wells was made in the 1990s by operators such as Maersk on the Dan field and BP on the Valhall field, in addition to onshore experiences with various operators such as UPRC in the Austin chalk and Arco in Alaska (the North Slope operational reality being effectively similar to offshore). Therefore, it is with great satisfaction that this month’s technical section includes papers demonstrating technologies from unconventionals that are beginning to be used to develop these offshore opportunities further.

This month’s selections highlight a number of such applications, including open hole and cased hole, ball-drop actuated, and proppant plug staging. Most of the tools and approaches developed (onshore) for high efficiency in low-permeability propped fracturing are not currently wholly applicable to higher-permeability (offshore) environments because they typically depend on overdisplacement by design. However, these technologies are a fast-moving target, with highly cost- and time- efficient coiled-tubing (CT) underdisplacement techniques emerging now across unconventional plays. This means that we should see articles here very soon on these CT-deployed propped-fracturing approaches as they move offshore.

As these innovations gain widespread acceptance, I would expect that the application of offshore fracturing will become a more attractive proposition once again. However, in all cases, the most critical aspects to achieving success will be that the technologies selected not only be fit-for-purpose but also reflect the formation quality and completion philosophy, rather than trying to fit square pegs into round holes. JPT

Recommended additional reading at OnePetro: www.onepetro.org.

SPE 170773 Flushing Away the Profit: The Potential Misapplication of Unconventional Fracturing Technology on a Global Scale by M. Rylance, BP, et al.

OTC 24179 Drilling and Completing Cascade and Chinook Wells: A Design and Execution Case History by Flavio Dias De Moraes, Petrobras, et al.

OTC 25321 Ultrahigh-Strength Proppant Developed for Deep, Offshore Completions by Terry Palisch, Carbo Ceramics, et al.
Assisted-History-Matching Benchmarking: Design-of-Experiments-Based Techniques
Authors: Wilson Adam
Published: February 2016

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 170690, “Assisted-History-Matching Benchmarking: Design-of- Experiments-Based Techniques,” by Eric Bhark, SPE, and Kaveh Dehghani, SPE, Chevron Energy Technology Company, prepared for the 2014 SPE Annual Technical Conference and Exhibition, Amsterdam, 27–29 October. The paper has not been peer reviewed.

As the role of reservoir-flow simulation increasingly affects existing operations and field-development decisions, it follows that rigor, fitness, and consistency should be imposed on the calibration of reservoir-flow models to dynamic data through history matching. To evaluate the applicability of the diverse techniques available, a study was performed to benchmark common assisted-history-matching (AHM) techniques. To benchmark the techniques consistently, a set of standards was defined against which each was evaluated. Of the techniques evaluated, the design-of-experiments (DOE) -based approach uniquely satisfied all requirements.

Introduction

In order to understand the practical utility of the wealth of history-matching techniques reported, a study was performed to benchmark four AHM techniques that have been applied in the oil and gas industry for asset-management applications— DOE-based methods, genetic algorithm, ensemble Kalman filter and smoother, and streamline-based generalized travel-time inversion. The techniques were tested against a comprehensive suite of modeling requirements for various operations-and business-related applications.

While all techniques were found to have unique advantages and limitations, the DOE-based approach was consistently confirmed as the most robust in terms of compatibility with a broad range of asset types, algorithmic simplicity, history-match quality, and uncertainty quantification. The foundation for this proposal lies in the definition of capabilities that, the authors propose, a technique should encompass if any generic history-matching study is to be completed successfully. These involve the capability of a technique to

Parameterize and calibrate any reservoir attribute

Integrate with any type of numerical-simulation method and grid structure for any runtime duration

Quantify any type of reservoir and production response into one or more history-matching metrics for their assimilation into the reservoir model

Generate an ensemble of equivalently calibrated flow models suitable for probabilistic analysis
Impact of Brine Composition on Calcite Wettability: A Sensitivity Study
Authors: AlShaikh Murtdha , Mahadevan Jagannathan
Published: February 2016

Brine composition change has a significant demonstrated impact on the recovery of oil in laboratory corefloods. Although low-salinity waterflood in clastics has been studied extensively, the impact of brine composition on the wettability and recovery in carbonates is relatively less understood and studies are more recent. Wettability measurements by use of contact angles can reflect the surface energy changes caused by adsorption of compounds present in crude oil and the electrostatic, structural components caused by the formation of the double layer.

In this study, the impact of ion composition on the contact angles and interfacial tensions (IFTs) between crude oil, brine, and restored/aged calcite-mineral surface is studied by use of a drop-profile-analysis method. A 13-factor experimental design is used to quantify the impact of six salts and seven interactions. This experimental method design, following the Taguchi method (Roy 1990), is used to identify the combination of different salts that leads to the lowest oil-wetness and highest water-wetness as measured through the contact angles. In addition, the impact of the total dissolved solids (TDS) on both the wettability and the IFT is studied for the selected crude oil/brine system.

The analysis of variance of the measurements shows that the Alkali/Alkaline Earth metal chloride concentration has a significant impact on the wettability measured with static contact angles. The interactions between sodium chloride and sodium sulfate concentration; between sodium chloride and magnesium chloride salt concentration; and between sodium chloride and calcium chloride concentration are significant. The most-favorable interaction response is obtained at the highest sodium sulfate concentration along with lower sodium chloride, calcium chloride, and magnesium chloride concentrations.

Therefore, a combination of higher concentration of sulfate anions with lower cation concentration and reduced salinity can lead to more-water-wet conditions. This composition is found to lead to the lowest contact angle or the most-water-wet condition. It is interesting to note that the lowest contact angle of approximately 29 ° (highly water-wet) is obtained with a relatively high TDS content of 134.5 g/L. This observation is in line with some of the recent studies reported in the literature on carbonate-rock corefloods and offers a fundamental explanation.
Semi-quantitative estimation of Escherichia coli levels in public drinking water sources in northern Haiti
Authors: Gerges Daniel I. , LaPlant William G. , Hyde James N. , Previl Harold , Forrester Janet
Published: February 2016

Prior research in Milot, Haiti, documented that public water sources are commonly fecally contaminated, as indicated by the presence of Escherichia coli. However, the degree of contamination was not assessed. In this study, the degree of fecal contamination in public drinking water sources was determined. Further, the usefulness of sanitary inspection surveys to predict fecal contamination was evaluated. A convenience sample of public water sources was tested using a semi-quantitative assay, which estimates the most probable number (MPN) of E. coli/100 mL of water. Each source was evaluated using the World Health Organization sanitary inspection score and classified as improved or unimproved. Sixty-three water sources were tested, of which 27 (43%) had <1 MPN/100 mL, 19 (30%) were contaminated from 1 to 100 MPN/100 mL, and 17 (27%) were contaminated with >100 MPN/100 mL. Some improved water sources were contaminated with >100 MPN/100 mL. The sanitary inspection score did not distinguish between sources that were and were not contaminated with E. coli. In Milot, Haiti, public water sources can be highly contaminated with E. coli. Since neither the categorization of a water source as improved or unimproved nor the sanitary inspection score can predict contamination, routine microbiological testing is justified.
Update on fluid biomarkers for concussion
Authors: Zetterberg Henrik , Morris Huw R , Hardy John , Blennow Kaj
Published: February 2016

Concussions are difficult to diagnose and symptoms may not appear immediately. As an accurate initial diagnosis has profound implications for the clinical management, there is an unmet need for better diagnostic tools. Fluid biomarkers for CNS injury may represent such tools. These markers are often proteins, peptides or other molecules with selective or high expression in the brain, which can be measured in the cerebrospinal fluid or blood as they leak out or get secreted into the biofluid in response to the injury. Here, we review the literature on fluid markers of neuronal, axonal and astroglial injury and response mechanisms to diagnose CNS injury upon head impact and to determine when the injurious process has resolved.
Diaphragm Pacing as a Rehabilitative Tool for Patients With Pompe Disease Who Are Ventilator-Dependent: Case Series
Authors: Smith Barbara K. , Fuller David D. , Martin A. Daniel , Lottenberg Lawrence , Islam Saleem , Lawson Lee Ann , Onders Raymond P. , Byrne Barry J.
Published: February 2016

Background and Purpose

Pompe disease is an inherited disorder notable for severe, progressive ventilatory compromise. Although ventilatory failure has been attributed to myofiber dysfunction secondary to diaphragmatic glycogen accumulation, neural involvement of the phrenic motor system is also a prominent feature. Direct diaphragm pacing supplements respiratory function in other disorders of the phrenic motor system. Accordingly, it is hypothesized that augmented neuromuscular activity via diaphragm pacing would promote weaning from mechanical ventilation in patients with Pompe disease who are unresponsive to conventional, muscle-directed treatments.

Case Description

Three patients with Pompe disease developed diaphragm paresis that resulted in chronic mechanical ventilation dependence. After preoperative inspiratory muscle strengthening exercises failed to improve function, fine-wire pacing electrodes were laparoscopically implanted into the diaphragm. Diaphragm conditioning was initiated the first postoperative week and consisted of gradual increases in stimulation parameters, lengthening of stimulation sessions, and ventilator weaning. Ventilation and intramuscular electromyographic activity were recorded periodically during conditioning to quantify diaphragm neuromuscular function.

Outcomes

During paced breathing without mechanical ventilation, tidal volumes increased, and 2 patients were weaned from daytime ventilator dependence within the first 3 months of pacing, which has been sustained over the long-term. A third patient reduced reliance on daytime ventilation, but weaning was delayed by malacia of the large airways. In all patients, pacing appeared to facilitate spontaneous phrenic motor unit activity during independent breathing without ventilator or pacer support.

Discussion

The findings are consistent with the view that diaphragm pacing has potential rehabilitative value to reduce reliance on mechanical ventilation in people with Pompe disease, but further study is needed. Diaphragm pacing represents a paradigm shift in the management of respiratory insufficiency for Pompe disease that warrants further controlled examination.
Non-invasive brain stimulation and robot-assisted gait training after incomplete spinal cord injury: A randomized pilot study
Authors: Raithatha Ravi , Carrico Cheryl , Powell Elizabeth Salmon , Westgate Philip M. , Chelette II Kenneth C. , Lee Kara , Dunsmore Laura , Salles Sara , Sawaki Lumy
Published: February 2016

BACKGROUND:

Locomotor training with a robot-assisted gait orthosis (LT-RGO) and transcranial direct current stimulation (tDCS) are interventions that can significantly enhance motor performance after spinal cord injury (SCI). No studies have investigated whether combining these interventions enhances lower extremity motor function following SCI.

OBJECTIVE:

Determine whether active tDCS paired with LT-RGO improves lower extremity motor function more than a sham condition, in subjects with motor incomplete SCI.

METHODS:

Fifteen adults with SCI received 36 sessions of either active ( n = 9) or sham ( n = 6) tDCS (20 minutes) preceding LT-RGO (1 hour). Outcome measures included manual muscle testing (MMT; primary outcome measure); 6-Minute Walk Test (6MinWT); 10-Meter Walk Test (10MWT); Timed Up and Go Test (TUG); Berg Balance Scale (BBS); and Spinal Cord Independence Measure-III (SCIM-III).

RESULTS:

MMT showed significant improvements after active tDCS, with the most pronounced improvement in the right lower extremity. 10MWT, 6MinWT, and BBS showed improvement for both groups. TUG and SCIM-III showed improvement only for the sham tDCS group.

CONCLUSION:

Pairing tDCS with LT-RGO can improve lower extremity motor function more than LT-RGO alone. Future research with a larger sample size is recommended to determine longer-term effects on motor function and activities of daily living.
Factors influencing acceptance of disability among stroke patients in Tianjin, China:A cross-sectional study
Authors: Chai Qianwen , Yuan Zhifang , Jin Yi , Zhang Qing
Published: February 2016

BACKGROUND:

Stroke has become the leading cause of acquired disability worldwide. Psychological maladjustment and related reactions for stroke disability has subsequently revealed a negative impact on stroke rehabilitation process. Acceptance of disability (AOD) is widely confirmed as a critical factor for psychosocial regulation and disability acceptance.

OBJECTIVE:

This study aims to investigate acceptance of disability and its influencing factors among stroke patients in China.

METHODS:

A total of 220 hospitalized stroke patients were investigated using questionnaire on demographics and disease characters, Adaptation Of Disability Scale-Revised, and other psychological instruments: Medical Coping Modes Questionnaire (MCMQ), Functional Activities Questionnaire (FAQ), Self-Rating Depression Scale (SDS), and Perceived Social Support Scale (PSSS).

RESULTS:

The mean score of AOD is 74.15 (range 32∼128), which reflected a moderate level of disability acceptance among stroke patients in China. Statistical analysis showed that confrontation, the understanding of stroke, self-rating depression, ability of functional activities and family support were major factors affecting acceptance of disability among disabled stroke patients, which explained 49.6% of the total variance.

CONCLUSIONS:

In clinical practice, professionals should identify patients with low levels of disability acceptance and explore effective psychological intervention model on the theoretical foundation of different dimensions in AOD theory and related predictors.
Is non-invasive neuromuscular electrical stimulation effective in severe chronic neurogenic dysphagia? Reporton a post-traumatic brain injury patient
Authors: Calabrò Rocco Salvatore , Nibali Valeria Conti , Naro Antonino , Floridia Daniela , Pizzimenti Maria , Salmeri Lucia , Salviera Carlo , Bramanti Placido
Published: February 2016

BACKGROUND:

Neurogenic dysphagia is a difficulty in swallowing induced by nervous system disease. It often causes serious complications, which are preventable if dysphagia is properly managed. There is growing debate concerning the usefulness of non-invasive neuromuscular electrical stimulation (NMES) in treating swallowing dysfunction.

OBJECTIVE:

Aim of this study was to assess the effectiveness of Vitalstim© device, and to investigate the neurophysiological mechanisms underlying functional recovery.

METHODS:

A 34-year-old man, affected by severe chronic dysphagia following traumatic brain injury, underwent two different intensive rehabilitation trainings, including either conventional rehabilitation alone or coupled to Vitalstim training. We evaluated patient swallowing function in two separate sessions ( i.e. before and after the two trainings) by means of ad hoc swallowing function scales and electrophysiological parameters (rapid paired associative stimulation). The overall Vitalstim program was articulated in 6 weekly sessions for 6 weeks.

RESULTS:

The patient did not report any side-effect either during or following both the intensive rehabilitation trainings. We observed an important improvement in swallowing function only after Vitalstim training. In fact, the patient was eventually able to safely eat even solid food.

CONCLUSIONS:

This is the first report objectively suggesting (by means of rPAS) a correlation between the brain neuroplastic changes induced by Vitalstim and the swallowing function improvement. It is hypothesizable that Vitalstim may have targeted cortical (and maybe subcortical) brain areas that are recruited during the highly coordinated function of swallowing, and it may have thus potentiated the well-known neuroplastic changes induced by repetitive and intensive swallowing exercises, probably thanks to metaplasticity phenomena.
Transfer effects of errorless Goal Management Training on cognitive function and quality of life in brain-injured persons
Authors: Bertens Dirk , Kessels Roy P.C. , Boelen Danielle H.E. , Fasotti Luciano
Published: February 2016

BACKGROUND:

Previous findings had shown that the addition of errorless learning to traditional Goal Management Training (GMT) resulted in superior results when training everyday tasks in persons with executive deficits after brain injury.

OBJECTIVE:

To investigate the additional effects of an errorless GMT on cognitive function and quality of life after acquired brain injury.

METHODS:

This is a supplementary analysis of findings from an RCT in which 67 patients with executive impairments after acquired brain injury were randomly allocated to an experimental errorless GMT ( n = 33) or conventional GMT ( n = 34) to train two individually chosen everyday tasks. Objective cognitive function using neuropsychological tests, subjective cognitive complaints and quality of life using questionnaires were assessed before and after training.

RESULTS:

No significant interaction effects between these three types of outcome measures and the two forms of GMT were found. Irrespective of treatment, performance on two executive tests (Modified Six Elements Test; p = 0.006, Zoo Map test; p = 0.001) improved and daily executive function problems as reported by the participants (EFI; p = 0.001) and proxies (DEX; p = 0.01) diminished.

CONCLUSIONS:

Besides the previously found superiority of errorless GMT when training everyday tasks, additional improvements in cognition and quality of life did not differ between the two treatments.
Application of 7-azaisatins in enantioselective Morita–Baylis–Hillman reaction
Authors: He Qing , Zhan Gu , Du Wei , Chen Ying-Chun
Published: February 2016

7-Azaisatin and 7-azaoxindole skeletons are valuable building blocks in diverse biologically active substances. Here 7-azaisatins turned out to be more efficient electrophiles than the analogous isatins in the enantioselective Morita–Baylis–Hillman (MBH) reactions with maleimides using a bifunctional tertiary amine, β-isocupreidine (β-ICD), as the catalyst. This route allows a convenient approach to access multifunctional 3-hydroxy-7-aza-2-oxindoles with high enantiopurity (up to 94% ee). Other types of activated alkenes, such as acrylates and acrolein, could also be efficiently utilized.
INFRARED CONTINUUM AND LINE EVOLUTION OF THE EQUATORIAL RING AROUND SN 1987A
Authors: Arendt Richard G. , Dwek Eli , Bouchet Patrice , Danziger I. John , Frank Kari A. , Gehrz Robert D. , Park Sangwook , Woodward Charles E.
Published: February 2016

Spitzer observations of SN 1987A have now spanned more than a decade. Since day ∼4000, mid-infrared (mid-IR) emission has been dominated by that from shock-heated dust in the equatorial ring (ER). From 6000 to 8000 days after the explosion, Spitzer observations included broadband photometry at 3.6–24 μm, and low and moderate resolution spectroscopy at 5–35 μm. Here we present later Spitzer observations, through day 10,377, which include only the broadband measurements at 3.6 and 4.5 μm. These data show that the 3.6 and 4.5 μm brightness has clearly begun to fade after day ∼8500, and no longer tracks the X-ray emission as well as it did at earlier epochs. This can be explained by the destruction of the dust in the ER on timescales shorter than the cooling time for the shocked gas. We find that the evolution of the late time IR emission is also similar to the now fading optical emission. We provide the complete record of the IR emission lines, as seen by Spitzer prior to day 8000. The past evolution of the gas as seen by the IR emission lines seems largely consistent with the optical emission, although the IR [Fe ii] and [Si ii] lines show different, peculiar velocity structures.
THE IMPACT OF ACCURATE EXTINCTION MEASUREMENTS FOR X-RAY SPECTRAL MODELS
Authors: Smith Randall K. , Valencic Lynne A. , Corrales Lia
Published: February 2016

Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption models exist, there are no useful scattering models in standard X-ray spectrum fitting tools, such as XSPEC. Nonetheless, X-ray halos, created by scattering from dust grains, are detected around even moderately absorbed sources, and the impact on an observed source spectrum can be significant, if modest, compared to direct absorption. By convolving the scattering cross section with dust models, we have created a spectral model as a function of energy, type of dust, and extraction region that can be used with models of direct absorption. This will ensure that the extinction model is consistent and enable direct connections to be made between a source's X-ray spectral fits and its UV/optical extinction.
PAN-CHROMATIC OBSERVATIONS OF THE RECURRENT NOVA LMC 2009a (LMC 1971b)
Authors: Bode M. F. , Darnley M. J. , Beardmore A. P. , Osborne J. P. , Page K. L. , Walter F. M. , Krautter J. , Melandri A. , Ness J.-U. , O’Brien T. J. , Orio M. , Schwarz G. J. , Shara M. M. , Starrfield S.
Published: February 2016

Nova LMC 2009a is confirmed as a recurrent nova (RN) from positional coincidence with nova LMC 1971b. The observational data set is one of the most comprehensive for any Galactic or extragalactic RN: optical and near-IR photometry from outburst until over 6 years later; optical spectra for the first 6 months, and Swift satellite ultraviolet (UV) and X-ray observations from 9 days to almost 1 year post-outburst. We find M

V
 = −8.4 ± 0.8r ± 0.7s and expansion velocities between 1000 and 4000 km s−1. Coronal line emission before day 9 indicates shocks in the ejecta. Strengthening of He ii
λ4686 preceded the emergence of the super-soft source (SSS) in X-rays at ∼63–70 days, which was initially very variable. Periodic modulations, P = 1.2 days, most probably orbital in nature, were evident in the UV and optical from day 43. Subsequently, the SSS shows an oscillation with the same period but with a delay of 0.28P. The progenitor system has been identified; the secondary is most likely a sub-giant feeding a luminous accretion disk. Properties of the SSS infer a white dwarf (WD) mass 1.1 M
⊙ ≲ M
WD ≲ 1.3 M
⊙. If the accretion occurs at a constant rate,

yr−1 is needed, consistent with nova models for an inter-eruption interval of 38 years, low outburst amplitude, progenitor position in the color–magnitude diagram, and spectral energy distribution at quiescence. We note striking similarities between LMC 2009a and the Galactic nova KT Eri, suggesting that KT Eri is a candidate RN.
STRUCTURE, STABILITY, AND EVOLUTION OF MAGNETIC FLUX ROPES FROM THE PERSPECTIVE OF MAGNETIC TWIST
Authors: Liu Rui , Kliem Bernhard , Titov Viacheslav S. , Chen Jun , Wang Yuming , Wang Haimin , Liu Chang , Xu Yan , Wiegelmann Thomas
Published: February 2016

We investigate the evolution of NOAA Active Region (AR) 11817 during 2013 August 10–12, when it developed a complex field configuration and produced four confined, followed by two eruptive, flares. These C-and-above flares are all associated with a magnetic flux rope (MFR) located along the major polarity inversion line, where shearing and converging photospheric flows are present. Aided by the nonlinear force-free field modeling, we identify the MFR through mapping magnetic connectivities and computing the twist number

for each individual field line. The MFR is moderately twisted (

) and has a well-defined boundary of high squashing factor Q. We found that the field line with the extremum

is a reliable proxy of the rope axis, and that the MFR's peak

temporarily increases within half an hour before each flare while it decreases after the flare peak for both confined and eruptive flares. This pre-flare increase in

has little effect on the AR's free magnetic energy or any other parameters derived for the whole region, due to its moderate amount and the MFR's relatively small volume, while its decrease after flares is clearly associated with the stepwise decrease in the whole region's free magnetic energy due to the flare. We suggest that

may serve as a useful parameter in forewarning the onset of eruption, and therefore, the consequent space weather effects. The helical kink instability is identified as the prime candidate onset mechanism for the considered flares.
STRUCTURE AND STABILITY OF MAGNETIC FIELDS IN SOLAR ACTIVE REGION 12192 BASED ON NONLINEAR FORCE-FREE FIELD MODELING
Authors: Inoue S. , Hayashi K. , Kusano K.
Published: February 2016

We analyze a three-dimensional (3D) magnetic structure and its stability in large solar active region (AR) 12192, using the 3D coronal magnetic field constructed under a nonlinear force-free field (NLFFF) approximation. In particular, we focus on the magnetic structure that produced an X3.1-class flare, which is one of the X-class flares observed in AR 12192. According to our analysis, the AR contains a multiple-flux-tube system, e.g., a large flux tube, with footpoints that are anchored to the large bipole field, under which other tubes exist close to a polarity inversion line (PIL). These various flux tubes of different sizes and shapes coexist there. In particular, the latter are embedded along the PIL, which produces a favorable shape for the tether-cutting reconnection and is related to the X-class solar flare. We further found that most of magnetic twists are not released even after the flare, which is consistent with the fact that no observational evidence for major eruptions was found. On the other hand, the upper part of the flux tube is beyond a critical decay index, essential for the excitation of torus instability before the flare, even though no coronal mass ejections were observed. We discuss the stability of the complicated flux tube system and suggest the reason for the existence of the stable flux tube. In addition, we further point out a possibility for tracing the shape of flare ribbons, on the basis of a detailed structural analysis of the NLFFF before a flare.
FORMING THE COLD CLASSICAL KUIPER BELT IN A LIGHT DISK
Authors: Shannon Andrew , Wu Yanqin , Lithwick Yoram
Published: February 2016

Large Kuiper Belt objects are conventionally thought to have formed out of a massive planetesimal belt that is a few thousand times its current mass. Such a picture, however, is incompatible with multiple lines of evidence. Here, we present a new model for the conglomeration of Cold Classical Kuiper Belt objects, out of a solid belt only a few times its current mass, or a few per cent of the solid density in a Minimum Mass Solar Nebula. This is made possible by depositing most of the primordial mass in grains of centimeter size or smaller. These grains collide frequently and maintain a dynamically cold belt out of which large bodies grow efficiently: an order-unity fraction of the solid mass can be converted into large bodies, in contrast to the

efficiency in conventional models. Such a light belt may represent the true outer edge of the solar system, and it may have effectively halted the outward migration of Neptune. In addition to the high efficiency, our model can also produce a mass spectrum that peaks at an intermediate size, similar to the observed Cold Classicals, if one includes the effect of cratering collisions. In particular, the observed power-law break observed at

for Cold Classicals, one that has been interpreted as a result of collisional erosion, may be primordial in origin.
THE MASS ACCRETION RATE OF GALAXY CLUSTERS: A MEASURABLE QUANTITY
Authors: De Boni C. , Serra A. L. , Diaferio A. , Giocoli C. , Baldi M.
Published: February 2016

We explore the possibility of measuring the mass accretion rate (MAR) of galaxy clusters from their mass profiles beyond the virial radius R
200. We derive the accretion rate from the mass of a spherical shell whose inner radius is 2R
200, whose thickness changes with redshift, and whose infall velocity is assumed to be equal to the mean infall velocity of the spherical shells of dark matter halos extracted from N-body simulations. This approximation is rather crude in hierarchical clustering scenarios where both smooth accretion and aggregation of smaller dark matter halos contribute to the mass accretion of clusters. Nevertheless, in the redshift range z = [0, 2], our prescription returns an average MAR within 20%–40% of the average rate derived from the merger trees of dark matter halos extracted from N-body simulations. The MAR of galaxy clusters has been the topic of numerous detailed numerical and theoretical investigations, but so far it has remained inaccessible to measurements in the real universe. Since the measurement of the mass profile of clusters beyond their virial radius can be performed with the caustic technique applied to dense redshift surveys of the cluster outer regions, our result suggests that measuring the mean MAR of a sample of galaxy clusters is actually feasible. We thus provide a new potential observational test of the cosmological and structure formation models.
MODELING THE EARLY MULTIWAVELENGTH EMISSION IN GRB 130427A
Authors: Fraija N. , Lee W. , Veres P.
Published: February 2016

One of the most powerful gamma-ray bursts, GRB 130427A was swiftly detected from GeV γ-rays to optical wavelengths. In the GeV band, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope observed the highest-energy photon ever recorded of 95 GeV and a bright peak in the early phase followed by emission temporally extended for more than 20 hr. In the optical band, a bright flash with a magnitude of 7.03 ± 0.03 in the time interval from 9.31 to 19.31 s after the trigger was reported by RAPTOR in r band. We study the origin of the GeV γ-ray emission, using the multiwavelength observation detected in X-ray and optical bands. The origin of the temporally extended LAT, X-ray, and optical flux is naturally interpreted as synchrotron radiation, and the 95 GeV photon and the integral flux upper limits placed by the high-altitude water Cerenkov observatory are consistent with synchrotron self-Compton from an adiabatic forward shock propagating into the stellar wind of its progenitor. The extreme LAT peak and the bright optical flash are explained through synchrotron self-Compton and synchrotron emission from the reverse shock, respectively, when the ejecta evolves in the thick-shell regime and carries a significant magnetic field.
PENTACARBON DIOXIDE (C5O2) FORMATION AND ITS ROLE AS A TRACER OF SOLAR SYSTEM EVOLUTION
Authors: Förstel Marko , Maksyutenko Pavlo , Mebel Alexander M. , Kaiser Ralf I.
Published: February 2016

Carbon monoxide is the second most abundant molecule on icy grains in the interstellar medium. These grains are under the influence of ionizing radiation, which induces the chemical reaction within the ice. Here we report the first observation of subliming pentacarbon dioxide (C5O2) after irradiation of pure carbon monoxide ice with energetic electrons. Our results show that pentacarbon dioxide is a stable reaction product in a carbon monoxide matrix that survives the sublimation in star-forming regions at sublimation temperatures of 175 K. Along with carbon suboxide (C3O2), this molecule can serve as a powerful tracer of the temperature history of formerly carbon monoxide rich ices in molecular clouds and star-forming regions.
The motives for service users visiting the wellness centres in Slovenia
Authors: Rančić Milica , Blešić Ivana , Đorđević Jasmina , Bole David
Published: February 2016

The word “wellness” is usually used to indicate a healthy balance of the mind, the body and the spirit that results in an overall feeling of the well-being. The wellness centers have become an inseparable part of the hotel facilities, at the instance of the users who come to these centers because of different motives. The purpose of this research is to examine the characteristics of a healthy-living market segment and its motivational behavior to wellness facilities in Slovenia. Hence, the objectives of this research are as follows: to identify the motivational characteristics of the tourists visiting the wellness centers and to study the relationship between the tourists’ healthy-living behavioral patterns and the motivational behavior in relation to the wellness facilities in Slovenia.
High-k MNOS-Like Stacked Dielectrics for Non-Volatile Memory Application
Authors: Khomenkova Larysa , Normand Pascal , Gourbilleau Fabrice , Slaoui Abdelilah , Bonafos Caroline
Published: February 2016

Charge-trapping memories such as SONOS and MONOS have attracted considerable attention as promising alternatives for next-generation flash memories due to dielectric layer’s scalability, process simplicity, power economy, operation versatility. Nevertheless, the continued miniaturization of the devices forces an application of high-k dielectrics. In this work high-k stacked dielectric structures based on the combination of Hf-based and SiNx materials were fabricated. Their structural and electrical properties versus deposition conditions are studied by means of FTIR-ATR and high-resolution TEM techniques. All samples demonstrated smooth surface (roughness below 1 nm) and abrupt interfaces between the different stacked layers. No crystallization of Hf-based layers was observed after annealing at 800°C for 30 min, demonstrating their amorphous nature and phase stability upon annealing. Electrical characterization was carried out for all samples through capacitance-voltage (C-V) measurements of MIS capacitors. Uniform C-V characteristics were measured along the samples for all stacks. Besides, significant flat-band hysteresis due to charging of the stacks caused by carrier injection from the substrate was observed for the structures with pure HfO2 layers.
Electrical Characterization and Parameter Extraction of Junctionless Nanowire Transistors
Authors: Rudenko Tamara , Barraud Sylvain , Georgiev Yordan M. , Lysenko Vladimir , Nazarov Alexei N.
Published: February 2016

This article presents a review of various methods for extracting the key parameters of junctionless (JL) MOSFETs, namely, the threshold voltage, flat-band voltage, doping concentration, carrier mobility, and parasitic series resistance. The applicability and limitations of different methods are analyzed using numerical simulations and experimental data for planar and tri-gate nanowire JL transistors with various nanowire widths.
Hopping Conduction in Structures with Ge Nanoclusters Grown on Oxidized Si (001)
Authors: Lysenko Vladimir , Gomeniuk Y.V. , Kudina Valeriya N. , Garbar Nikolay , Kondratenko Sergey , Melnichuk Yevgenij Ye. , Kozyrev Yurii N.
Published: February 2016

Conductivity and capacitance in structures with Ge nanoclusters grown on oxidized Si (001) with different morphology have been investigated for the temperature range 120-290 K and frequencies 1 kHz-1MHz in co-planar geometry. It was found that structures exhibited T-1/3 conductivity dependence. The Mott’s variable range hopping through quasi-band of localized states at the Fermi level of Ge nanoclusters and their interfaces was found to be the dominant transport mechanism in the surface conductivity channel. The quasi-band width depends of surface morphology varying in the range 110-130 meV, while the middle of the band is located at Ev+140 meV. The peak of reduced conductivity and capacitance were observed under conditions when Fermi level is in the middle of this band.
Morphology of the Interface “Silicon Wire - Nerve Fiber"
Authors: Klimovskaya A. , Vysotskaya N. , Chaikovsky Yu. , Korsak A. , Lichodievskiy V. , Ostrovskii I.
Published: February 2016

Recently study of the “silicon wire - nerve tissue’ interface has been in the focus of attention due to its potential use in recovering nervous system damage caused by injuries or diseases. The key objective of this research was to test the physicochemical state of the interface and to study its properties. Although much research has been done in this field, the process of interface formation was not thoroughly described from the surface physics point of view. In the current research specimens of the “silicon wire - nerve fiber" interface were made. Experiments were carried out in vivo. The interface morphology and mechanisms of adhesion were examined in more detail and a physical model of intermolecular interaction of silicon surface and nerve fiber was proposed.
Multichannel Fiber-Optic Ring Converters for Optical Sensors of Physical Quantities
Authors: Shapar V. , Lysenko Vladimir , Bondarenko Alla V.
Published: February 2016

The substantial achievements in the area of manufacturing technology for optical fiber bundles and fiber-optic transducers (FOTs) stimulated interest in their application in various sensors of physical quantities as well as in measuring instruments. Being insensitive to electromagnetic interferences, FOTs demonstrated high sensitivity to measured physical quantities. They made it possible to perform contactless measurements in many cases of hindered access to the objects under investigation. Their spark-and explosion-safety as well as manufacturing simplicity make FOT-based measuring instruments especially useful for application in coal-mining and oil-and-gas industry where the safety problems are of vital importance.
The Device-Technological Simulation of Local 3D SOI-Structures
Authors: Kogut Igor T. , Holota Victor I. , Druzhinin Anatoly , Dovhij V.V.
Published: February 2016

This paper presents the device-technological simulation of local 3D SOI structures. These structures are created by use microcavities under surface of silicon wafer. Is shown that proposed microcavities could be use as a constructive material for CMOS transistor array on the bulk silicon and 3D SOI-CMOS transistor array, as well as the sensitive elements and their combinations. Such structures allow creation and monolithic integration the CMOS, SOI-CMOS circuits and sensitive elements for IC and SoC.
Enhancement of Electron Spin Relaxation Time in Thin SOI Films by Spin Injection Orientation and Uniaxial Stress
Authors: Ghosh Joydeep , Osintsev Dmitry , Sverdlov V. , Selberherr Siegfried
Published: February 2016

The electron spin properties of semiconductors are of immense interest for their potential in spin-driven applications. Silicon is a perfect material for spintronics due to a long spin lifetime. Understanding the peculiarities of the subband structure and details of spin propagation in thin silicon films in the presence of the spin-orbit interaction is under scrutiny. We have performed simulations to obtain the surface roughness limited, acoustic-and optical-phonon mediated spin relaxation time, when the film is under shear strain. The degeneracy between the non-equivalent valleys is lifted by strain, which in turn subdues the dominating inter-valley relaxation components and increases the spin lifetime. We also elaborate on the injection orientation sensitive spin relaxation model and predict that the spin relaxation time is maximum, when the spin is injected in-plane, relative to the (001) oriented silicon film.
Magnetic Properties of Doped Si Whiskers for Spintronics
Authors: Druzhinin Anatoly , Ostrovskii Igor , Khoverko Yuriy , Yatsukhnenko Sergij
Published: February 2016

Study the magnetic properties of Si whiskers, the concentration of which corresponds to a dielectric and metal side of metal-insulator transition, is performed. Percolation laws of the magnetic clusters formation, that is important for development of spintronic devices, are considered.
The Effect of Incorporation of Hydrocarbon Groups on Visible Photoluminescence of Thermally Treated Fumed Silica
Authors: Vasin Andriy , Verovsky Igor , Tyortykh Valentyn , Bolbukh Yulia , Kisel Dmytriy , Rudko Galyna , Gule Yevgeniy , Piryatinsky Yurii , Starik Sergii , Nazarov Alexei , Lysenko Vladimir
Published: February 2016

Methyl, methoxy and alcoxy groups with different number of carbon atoms were chemically grafted onto the surface of fumed silica nanoparticles. After chemical modification the nanopowders were annealed in vacuum at 700 °C. The effect of the amount of carbon atoms in grafted hydrocarbon groups and type of bonding to silica surface (Si-C v.s. Si-O-C) were studied. It was demonstrated that carbon incorporation results in the development of broad band photoluminescence that covers the wholevisible spectral range. Increasing of carbon incorporation resulted in increasing of photoluminescence intensity and red shift of the photoluminescence band maximum.
Bainitic Steels, their Characteristics and Applications
Authors: Shimanov Maxim , Korpala Grzegorz , Terzic Adnan , Kawalla Rudolf
Published: February 2016

Abstract. Excellent combination of mechanical properties makes bainitic steels very attractive for commercial application. The most potential benefit of bainitic steels is found in the lightweight design of car bodies. The chemical composition, productions process and the austenite state control the properties of those steels. To reach the target of the correct component design it is important to focus on transformation kinetics. High carbon steels have been investigated, which contain approximately 0.5% C, 1.5% Si, 1.5% Mn, 0.9% Cr and 1.5% Cu. It’s expected to form a carbide free bainitic microstructure due to the Si addition. The residual austenite in the microstructure of high carbon bainitic steels ensures the forming ability besides the high strength. Maximum tensile strength is 1650 MPa and elongation is around 30%. Those steels can be used to produce large scale components.
Upgraded Railway Front Searchlight Design Plastic Deformations by its Vibrations with Resonance Frequencies
Authors: Abulkhanov Stanislav Rafaelevich , Goryainov Dmitrii Sergeevich
Published: February 2016

Natural frequencies of the four upgraded front searchlight designs were received in ANSYS software environment. In the first case serial front searchlight incandescent electric lamp was replaced by a LED group which was mounted on the one-piece cylinder backing. The second front searchlight design had the backing which was upgraded by a radial ribs and concentric rigidity ferrules. Analyze of the backing deformation character by vibrations with the natural frequencies established a number of design solutions which make it possible to raise front searchlight vibration resistance. By the front searchlight model were established that the natural frequencies of the searchlight with the one-piece backing appertain to the whole range of the train vibrations. Natural frequencies of the backing with perforation, rigidity ferrules, and radial ribs appertain to the low frequencies of the railway locomotive vibrations spectrum. On basis of devised methodology of analyze of the deformation and natural frequencies of the surface carrying a LED group the vibration-proof searchlight design was introduced and researched.
Testing Criterion Models of Destruction of Materials with Different Rheological Properties under Edge Cutting Machining
Authors: Alekseev V.P. , Khaimovich Alexander I.
Published: February 2016

In this article we perform comparative analysis of the criteria of fracture during blade machining simulation, characterized by high intensity of the strain rate (about 10-6 s-1). For each 3D virtual experiment a milling processing model has been developed in DEFORM software package. The character of chip segmentation during the simulation was determined the accepted failure criterion. The adequacy of the model was evaluated by full-scale experiment based on geometry of real chips.
Formation of Hard Alloys of Chromium Carbide and Titanium Powder Mixtures by Explosive Pressing
Authors: Kharlamov V.O. , Krokhalev Aleksandr Vasilevich , Kuz’min S.V. , Lysak V.I.
Published: February 2016

The production of a new type of hard alloys by explosive compaction of chromium carbide (Cr3C2) and titanium powder mixtures was investigated. The phase composition of the fabricated alloys was studied using scanning electron probe microanalysis. The chemical composition of the alloy components does not change, and no redistribution of the elements was observed. The formation characteristics of the interfaces between the material components during shock wave processing were investigated using electron microscopy. The explosion compaction of high melting carbide and metal powder mixtures results in the formation of consolidated hard alloys during the compaction stage.
Stamping of Hemispheric Surface Parts in Die Tool Equipped with Steel Elastic Element
Authors: Nesterenko Elena
Published: February 2016

In the present investigation, the innovated drawing method combined with calibration process by elastic steel element of hemispheric surface part is studded. During drawing process strong meridional lengthen strength appears. That influence on necking and differential deformation distribution. In its tern, that influence on sizes and surface accuracy. Elastic element, produced of spring steel and placed along with solid punch designed to calibrate part in final drawing stage due to elastic strength happened in it. A simulation of hemispheric surface part drawing with elastic element was held. Experiment demonstrates positive influence of elastic element to decrease necking till 15-18% from started thickness. The produced part has correct strain-stress state, exact surface and minimum dispersion of dimensions.