bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and Numerical Investigations on the Origins of Rotating Stall in a Propeller Turbine Runner Operating in No-Load Conditions
Authors: Houde Sébastien , Dumas Guy , Deschênes Claire
Published: March 2018

Hydraulic turbines are more frequently used for power regulation and thus spend more time providing spinning reserve for electrical grids. Spinning reserve requires the turbine to operate at its synchronous rotation speed, ready to be linked to the grid in what is termed the speed-no-load (SNL) condition. The turbine's runner flow in SNL is characterized by low discharge and high swirl leading to low-frequency high amplitude pressure fluctuations potentially leading to blade damage and more maintenance downtime. For low-head hydraulic turbines operating at SNL, the large pressure fluctuations in the runner are sometimes attributed to rotating stall. Using embedded pressure transducer measurements, mounted on runner blades of a model propeller turbine, and numerical flow simulations, this paper provides an insight into the inception mechanism associated with rotating stall in SNL conditions. The results offer evidence that the rotating stall is in fact associated with an unstable vorticity distribution not associated with the runner blades themselves.
Analysis of Mode and Dynamic Stability for Wind Turbine Rotating Blades
Authors: Zhang Jian-Ping , Gong Zhen , Guo Liang , Wu Helen
Published: March 2018

For large-scale offshore wind turbine rotating blades (NREL 5MW), the theoretical model of vibration due to fluid-structure interaction (FSI) is established, and the basic equations for modal analysis are given. Based on ANSYS workbench platform, the blade modal characteristics at different rotating speeds are analyzed, and further research on dynamic stability is carried out. The results indicate that the FSI and the blade rotation have a great influence on modal frequencies, which increase with the rotating speed of the blade under FSI. When the frequency of the periodic wind speed is close to the first-order natural frequency of the blade, both the maximum flapping displacement and the maximum von Mises stress increase with time, and the vibration divergence appears. At the safe tower clearance of 4.50 m, the critical value of the blade maximum von Mises stress shows a linear upward trend with the increase of the elasticity modulus, which provides technical references for optimization design and safe operation of wind turbine blades.
Long-Term Extreme Response Analysis of Marine Structures Using Inverse SORM
Authors: Giske Finn-Idar G. , Leira Bernt Johan , Øiseth Ole
Published: March 2018

In this paper, the first-order reliability method (FORM) found in connection with structural reliability analysis is first used in an inverse manner to efficiently obtain an approximate solution of the full long-term extreme response of marine structures. A new method is then proposed where the second-order reliability method (SORM) is used to improve the accuracy of the approximation, resulting in an inverse SORM (ISORM) approach. This method is compared with exact results obtained using full numerical integration. The new method is seen to achieve significantly improved accuracy, yet keep the number of required short-term response analyses within acceptable levels.
Friction and Wear Reduction Mechanisms of the Reciprocating Contact Interfaces Using Nanolubricant Under Different Loads and Speeds
Authors: Ahmed Ali Mohamed Kamal , Xianjun Hou , Essa F. A. , Abdelkareem Mohamed A. A. , Elagouz Ahmed , Sharshir S. W.
Published: March 2018

This study aims to reveal the roles and mechanisms of Al2O3/TiO2 hybrid nanoparticles into the lube oils which could reinforce engine components durability via reducing the friction, wear, or fuel economy in automotive engines. The tribological tests were carried out under different sliding speeds from 0.21 to 1.75 m/s and loads from 30 to 250 N using a reciprocating tribometer to simulate the ring/liner interface in the engine according to ASTM G181. The tribological results using hybrid nanolubricants suggested that the friction coefficient and wear rate of the ring decreased in the ranges 39–53% and 25–33%, respectively, compared to nanoparticles-free lube oil. The combined evidence of the worn surfaces analysis confirmed that the key mechanisms in antifriction and antiwear are a combination of the nanoparticles rolling mechanism and the replenishment mechanism of tribofilms on the sliding contact interfaces. In addition, a tribofilm formed on the rubbing surfaces is not only from the nanoparticles but also from Fe which is formed as a result of iron debris particles and oil additive package such as P and S originating from zinc dialkyldithiophosphate.
Identification of Dynamic Characteristics of Hybrid Bump-Metal Mesh Foil Bearings
Authors: Zhao Zilong , Feng Kai , Zhao Xueyuan , Liu Wanhui
Published: March 2018

The stability of oil-free high-speed turbo-machinery can be effectively improved by increasing the damping characteristic of the gas foil bearing (GFB). Novel hybrid bump-metal mesh foil bearings (HB-MFBs) have been previously developed. Prior experimental results show that the parallel combination of bump structure and metal mesh not only can improve the structure stiffness but also provide better damping property compared with the bump-type foil structure. To investigate the dynamic behavior of floating HB-MFBs and promote its application, this study measured the dynamic force coefficients of HB-MFBs on a rotating test rig. The vibrations of HB-MFBs with different mesh densities (40%, 32.5%, and 25%) and a generation І bump-type foil bearing (BFB) with similar size are measured under static and impact loads to estimate the bearing characteristics. Static load test results show that the linear stiffness decreases when the air film is generated (from 0 rpm to 20 krpm) but increases gradually with speed (from 20 krpm to 30 krpm, and 40 krpm). Moreover, the dynamic force coefficients of HB-MFBs indicate the significant influence of metal mesh density on bearing dynamic characteristics. The growth in block density increases the dynamic stiffness and damping coefficients of bearing. The comparison of HB-MFB (32.5% and 40%) and BFB emphasizes the good damping characteristics of HB-MFB.
Vibration Response Characteristics of Quasi-Periodic Sandwich Beam With Magnetorheological Visco-Elastomer Core Under Random Support Excitations
Authors: Ying Z. G. , Ni Y. Q. , Huan R. H.
Published: March 2018

The vibration control of a sandwich beam with supported mass subjected to random support motion excitations can be performed using magnetorheological visco-elastomer core with adjustable dynamic properties. The periodic distributions of geometrical and physical parameters of the sandwich beam can improve its vibration response characteristics. To further improve characteristics or reduce responses, the quasi-periodic sandwich beam with supported mass under random excitations is studied. The facial layer thickness and core layer modulus of the sandwich beam are considered as quasi-periodic distributions. The partial differential equations for the horizontal and vertical coupling motions of the sandwich beam are derived and converted into ordinary differential equations for multi-degrees-of-freedom (DOFs) vibration. The expressions of frequency response and response spectral densities of the sandwich beam are obtained. Numerical results are given to illustrate the greatly improvable vibration response characteristics of the sandwich beam and the outstanding relative reduction localization of antiresonant responses. The proposed quasi-periodic distribution and analysis method can be used for the vibration control design of sandwich beams subjected to random excitations.
Steady-State Calibration of a Diesel Engine in Computational Fluid Dynamics Using a Graphical Processing Unit-Based Chemistry Solver
Authors: Gao Jian , Grover Ronald O. , Gopalakrishnan Venkatesh , Diwakar Ramachandra , Elwasif Wael , Dean Edwards K. , Finney Charles E. A. , Whitesides Russell A.
Published: March 2018

The prospect of analysis-driven precalibration of a modern diesel engine is extremely valuable in order to significantly reduce hardware investments and accelerate engine designs compliant with stricter fuel economy regulations. Advanced modeling tools, such as CFD, are often used with the goal of streamlining significant portions of the calibration process. The success of the methodology largely relies on the accuracy of analytical predictions, especially engine-out emissions. However, the effectiveness of CFD simulation tools for in-cylinder engine combustion is often compromised by the complexity, accuracy, and computational overhead of detailed chemical kinetics necessary for combustion calculations. The standard approach has been to use skeletal kinetic mechanisms (∼50 species), which consume acceptable computational time but with degraded accuracy. In this work, a comprehensive demonstration and validation of the analytical precalibration process is presented for a passenger car diesel engine using CFD simulations and a graphical processing unit (GPU)-based chemical kinetics solver (Zero-RK, developed at Lawrence Livermore National Laboratory, Livermore, CA) on high performance computing resources to enable the use of detailed kinetic mechanisms. Diesel engine combustion computations have been conducted over 600 operating points spanning in-vehicle speed-load map, using massively parallel ensemble simulation sets on the Titan supercomputer located at the Oak Ridge Leadership Computing Facility. The results with different mesh resolutions have been analyzed to compare differences in combustion and emissions (NOx, carbon monoxide CO, unburned hydrocarbons (UHC), and smoke) with actual engine measurements. The results show improved agreement in combustion and NOx predictions with a large n-heptane mechanism consisting of 144 species and 900 reactions with refined mesh resolution; however, agreement in CO, UHC, and smoke remains a challenge.
Conceptualizing Obesity as a Chronic Disease: An Interview With Dr. Arya Sharma
Authors: Sharma Arya M. , Goodwin Donna L. , Causgrove Dunn Janice
Published: March 2018

Dr. Arya M. Sharma challenges the conventional wisdom of relying simply on “lifestyle” approaches involving exercise, diet, and behavioral interventions for managing obesity, suggesting that people living with obesity should receive comprehensive medical interventions similar to the approach taken for other chronic diseases such as Type 2 diabetes or hypertension. He purports that the stigma-inducing focus on self-failing (e.g., coping through food, laziness, lack of self-regulation) does not address biological processes that make obesity a lifelong problem for which there is no easy solution. Interdisciplinary approaches to obesity are advocated, including that of adapted physical activity. Physical activity has multifaceted impacts beyond increasing caloric expenditure, including improved sleep, better mood, increased energy levels, enhanced self-esteem, reduced stress, and an enhanced sense of well-being. The interview with Dr. Sharma, transcribed from a keynote address delivered at the North American Adapted Physical Activity Symposium on September 22, 2016, in Edmonton, AB, Canada, outlines his rationale for approaching obesity as a chronic disease.
Independent Associations and Interactions of Perceived Neighborhood and Psychosocial Constructs on Adults’ Physical Activity
Authors: Dwyer Laura A. , Patel Minal , Nebeling Linda C. , Oh April Y.
Published: March 2018

Background: Neighborhood and psychosocial variables are related to physical activity (PA), yet interactions between these factors in predicting PA are infrequently studied. Methods: This analysis examines the independent associations and interactions between self-reported neighborhood and psychosocial variables in relation to moderate to vigorous PA (MVPA) among adults from a US panel sample. Results: In adjusted models, neighborhood social capital was positively associated with meeting MVPA guidelines. Fewer barriers, greater self-efficacy, and greater autonomous motivation also corresponded with greater odds of meeting MVPA guidelines. An interaction between social capital and autonomous motivation showed that social capital was only associated with MVPA when autonomous motivation was high. Participants who reported both high autonomous motivation and high social capital were most likely to meet MVPA guidelines. Conclusions: Neighborhood social capital, barriers, self-efficacy, and autonomous motivation may be important correlates in promoting adults’ PA. Future directions include using objective neighborhood and PA data in similar analyses and investigating associations of neighborhood and psychosocial variables with multiple PA activities. Intervention research to promote PA should also examine whether effects of interventions targeting psychosocial constructs are moderated by features of an individual’s neighborhood or whether perceived social capital can be addressed in interventions in conjunction with psychosocial variables.
Diffusion-weighted imaging is helpful in the accurate non-invasive diagnosis of breast abscess: correlation with necrotic breast cancer
Authors: Wang Cuiyan , Eghtedari Mohammad , Yang Wei Tse , Dogan Basak Erguvan
Published: March 2018

Clinical differentiation of atypical breast abscesses from necrotic tumour in premenopausal women is challenging and may delay appropriate therapy. In this case report, we present a 36-year-old woman with signs, symptoms and conventional imaging features of malignancy who underwent breast MRI. On diffusion-weighted imaging (DWI), profoundly low apparent diffusion coefficient values were a distinguishing sign of breast abscess from necrotic breast cancer, and helped manage the patient conservatively. We present a companion case of necrotic breast tumour highlighting significant differences in DWI.
Are methodological quality and completeness of reporting associated with citation-based measures of publication impact? A secondary analysis of a systematic review of dementia biomarker studies
Authors: Mackinnon Shona , Drozdowska Bogna A , Hamilton Michael , Noel-Storr Anna H , McShane Rupert , Quinn Terry
Published: March 2018

Objective

To determine whether methodological and reporting quality are associated with surrogate measures of publication impact in the field of dementia biomarker studies.

Methods

We assessed dementia biomarker studies included in a previous systematic review in terms of methodological and reporting quality using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) and Standards for Reporting of Diagnostic Accuracy (STARD), respectively. We extracted additional study and journal-related data from each publication to account for factors shown to be associated with impact in previous research. We explored associations between potential determinants and measures of publication impact in univariable and stepwise multivariable linear regression analyses.

Outcome measures

We aimed to collect data on four measures of publication impact: two traditional measures—average number of citations per year and 5-year impact factor of the publishing journal and two alternative measures—the Altmetric Attention Score and counts of electronic downloads.

Results

The systematic review included 142 studies. Due to limited data, Altmetric Attention Scores and electronic downloads were excluded from the analysis, leaving traditional metrics as the only analysed outcome measures. We found no relationship between QUADAS and traditional metrics. Citation rates were independently associated with 5-year journal impact factor (β=0.42; p<0.001), journal subject area (β=0.39; p<0.001), number of years since publication (β=-0.29; p<0.001) and STARD (β=0.13; p<0.05). Independent determinants of 5-year journal impact factor were citation rates (β=0.45; p<0.001), statement on conflict of interest (β=0.22; p<0.01) and baseline sample size (β=0.15; p<0.05).

Conclusions

Citation rates and 5-year journal impact factor appear to measure different dimensions of impact. Citation rates were weakly associated with completeness of reporting, while neither traditional metric was related to methodological rigour. Our results suggest that high publication usage and journal outlet is not a guarantee of quality and readers should critically appraise all papers regardless of presumed impact.
Perceptions of rounding checklists in the intensive care unit: a qualitative study
Authors: Hallam Bethany Danae , Kuza Courtney C , Rak Kimberly , Fleck Jessica C , Heuston Melanie M , Saha Debjit , Kahn Jeremy M
Published: March 2018

Background

Rounding checklists are an increasingly common quality improvement tool in the intensive care unit (ICU). However, effectiveness studies have shown conflicting results. We sought to understand ICU providers’ perceptions of checklists, as well as barriers and facilitators to effective utilisation of checklists during daily rounds.

Objectives

To understand how ICU providers perceive rounding checklists and develop a framework for more effective rounding checklist implementation.

Methods

We performed a qualitative study in 32 ICUs within 14 hospitals in a large integrated health system in the USA. We used two complementary data collection methods: direct observation of daily rounds and semistructured interviews with ICU clinicians. Observations and interviews were thematically coded and primary themes were identified using a combined inductive and deductive approach.

Results

We conducted 89 interviews and performed 114 hours of observation. Among study ICUs, 12 used checklists and 20 did not. Participants described the purpose of rounding checklists as a daily reminder for evidence-based practices, a tool for increasing shared understanding of patient care across care providers and a way to increase the efficiency of rounds. Checklists were perceived as not helpful when viewed as overstandardising care and when they are not relevant to a particular ICU’s needs. Strategies to improve checklist implementation include attention to the brevity and relevance of the checklist to the particular ICU, consistent use over time, and integration with daily work flow.

Conclusion

Our results provide potential insights about why ICU rounding checklists frequently fail to improve outcomes and offer a framework for effective checklist implementation through greater feedback and accountability.
Systemic inflammation and suicide risk: cohort study of 419 527 Korean men and women
Authors: Batty G David , Jung Keum Ji , Lee Sunmi , Back Joung Hwan , Jee Sun Ha
Published: March 2018

Background

Data from only one study have been used to examine the relationship between systemic inflammation and later suicide risk, and a strong positive association was apparent. More research is needed, particularly looking at gender, not least because women are seemingly more vulnerable to inflammation-induced mood changes than men.

Methods

The Korean Cancer Prevention Study had a cohort of over 1 million individuals aged 30–95 years at baseline examination between 1992 and 1995, when white blood cell count, our marker of systemic inflammation, was assessed.

Results

A mean of 16.6 years of mortality surveillance gave rise to 1010 deaths from suicide in 106 643 men, and 1019 deaths from suicide in 312 884 women. There was little evidence of an association between our inflammation marker and suicide mortality in men after multiple adjustments. In women, however, those in the second inflammation quartile and higher experienced around 30% increase risk of death (HR 1.35; 95% CI: 1.11–1.64).

Conclusions

Higher levels of systemic inflammation were moderately related to an elevated risk of suicide death in women but not in men.
The Stereotactic Intracerebral Hemorrhage Underwater Blood Aspiration (SCUBA) technique for minimally invasive endoscopic intracerebral hemorrhage evacuation
Authors: Kellner Christopher Paul , Chartrain Alexander G , Nistal Dominic A , Scaggiante Jacopo , Hom Danny , Ghatan Saadi , Bederson Joshua B , Mocco J
Published: March 2018

Background

Endoscopic intracerebral hemorrhage (ICH) evacuation techniques have gained interest as a potential therapeutic option. However, the instrumentation and techniques employed are still being refined to optimize hemostasis and evacuation efficiency.

Objective

We describe the application of a specific endoscopic technique in the treatment of ICH called the Stereotactic Intracerebral Hemorrhage Underwater Blood Aspiration (SCUBA) technique. It differs from previously described minimally invasive ICH interventions in that it combines two separate neuroendoscopic strategies in two phases, the first under dry-field conditions and the second using a wet-field strategy.

Methods

All patients who underwent endoscopic ICH evacuation with the SCUBA technique from December 2015 to September 2017 were included.

Results

The SCUBA technique was performed in 47 patients. The average evacuation percentage was 88.2% (SD 20.8). Active bleeding identified to derive from a specific source was observed in 23 (48.9%) cases. Active bleeding was addressed with irrigation alone in five cases (10.6%) and required electrocautery in 18 cases (38.3%). Intraoperative bleeding occurred in 3 patients (6.4%) and postoperative bleeding occurred in a single case (2.1%).

Conclusions

The SCUBA technique provides surgeons with a defined strategy for true endoscopic hematoma evacuation. In particular, the fluid-filled cavity in SCUBA Phase 2 has the potential to provide several advantages over the traditional air-filled strategy, including clear identification and cauterization of bleeding vessels and visualization of residual clot burden. Further investigation is necessary to compare this technique to others that are currently used.
Stratigraphic analysis of Late Wisconsin and Holocene glaciolacustrine deposits exposed along the Nottawasaga River, southern Ontario, Canada
Authors: Mulligan Riley P.M. , Eyles Carolyn H. , Bajc Andy F.
Published: March 2018

Analysis of 56 outcrop exposures in cut banks along the Nottawasaga River in southern Simcoe County, Ontario, Canada, has led to the identification of eight stratigraphic units (SU1–SU8) that represent a record of changing environmental conditions during deglaciation and exhibit strong controls on shallow groundwater flow in the region. The stratigraphic succession is floored by the Late Wisconsin Newmarket Till (SU1), which is locally overlain by ice-proximal debris flow deposits (SU2). These glacial sediments are overlain by glaciolacustrine silt rhythmites (SU3) that pass upwards into deltaic sand (SU4) and channelized fluviodeltaic sand and gravel (SU5). Lying above the fluvial deposits are widespread interbedded glaciolacustrine sands and silt (SU6), which coarsen up-section toward the ground surface. The succession is locally capped by fluviodeltaic (SU7) and younger fluvial (SU8) deposits. These SUs record sedimentary environments that existed during deglaciation of the region and provide insight into the evolution of glacial lakes Schomberg and Algonquin and the Nipissing phase of the upper Great Lakes. The environmental changes described from sediments along the Nottawasaga River provide insights into basin-scale events that occurred throughout the upper Great Lakes during deglaciation. Qualitative observations of groundwater discharge from sediments at outcrop faces are used to characterize the hydraulic function of the stratigraphic units as well as possible preferential groundwater flow pathways in the shallow subsurface.
Analysis of the structure of climate networks under El Niño and La Niña conditions
Authors: Graciosa Juan Carlos , Pastor Marissa
Published: March 2018

The El Niño-Southern Oscillation (ENSO) is the most important driver of natural climate variability and is characterized by anomalies in the sea surface temperatures (SST) over the tropical Pacific ocean. It has three phases: neutral, a warming phase or El Niño, and a cooling phase called La Niña. In this research, we modeled the climate under the three phases as a network and characterized its properties. We utilized the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) daily surface temperature reanalysis data from January 1950 to December 2016. A network associated to a month was created using the temperature spanning from the previous month to the succeeding month, for a total of three months worth of data for each network. Each site of the included data was a potential node in the network and the existence of links were determined by the strength of their relationship, which was based on mutual information. Interestingly, we found that climate networks exhibit small-world properties and these are found to be more prominent from October to April, coinciding with observations that El Niño occurrences peak from December to March. During these months, the temperature of a relatively large part of the Pacific ocean and its surrounding areas increase and the anomaly values become synchronized. This synchronization in the temperature anomalies forms links around the Pacific, increasing the clustering in the region and in effect, that of the entire network.
Circular geodesic radiation in Schwarzschild spacetime: A semiclassical approach
Authors: Bernar Rafael P. , Crispino Luís C. B. , Higuchi Atsushi
Published: March 2018

Extreme curvature settings and nontrivial causal structure of curved spacetimes may have interesting theoretical and practical implications for quantum field theories. Radiation emission in black hole spacetimes is one such scenario in which the semiclassical approach, i.e. quantum fields propagating in a nondynamical background spacetime, adds a very simple conceptual point of view and allows us to compute the emitted power in a straightforward way. Within this context, we reexamine sources in circular orbit around a Schwarzschild black hole, investigating the emission of scalar, electromagnetic and gravitational radiations. The analysis of the differences and similarities between these cases provide an excellent overview of the powerful conceptual and computational tool that is quantum field theory in curved spacetime.
Electromagnetic fields in vicinity of tidal charged static black hole
Authors: Turimov Bobur
Published: March 2018

In this paper, we study the contribution of the tidal charge in the electromagnetic field in the vicinity of the black hole in the braneworld, and present an analytical solution of Maxwell equations for the dipolar configuration of the vector potential of the electromagnetic field of the stationary current loop generated by the charged matter surrounding the black hole. In order to find the location of the current loop we find the radius of the stable circular orbit of the test particle, by considering the particle motion around the tidal charged black hole. Furthermore, we study the dipolar magnetic field in both interior and exterior regions of the current loop, respectively. Although all results are compared with those previously obtained in Schwarzschild space.
Neanderthal and Denisovan ancestry in Papuans: A functional study
Authors: Akkuratov Evgeny E. , Gelfand Mikhail S. , Khrameeva Ekaterina E.
Published: March 2018

Sequencing of complete nuclear genomes of Neanderthal and Denisovan stimulated studies about their relationship with modern humans demonstrating, in particular, that DNA alleles from both Neanderthal and Denisovan genomes are present in genomes of modern humans. The Papuan genome is a unique object because it contains both Neanderthal and Denisovan alleles. Here, we have shown that the Papuan genomes contain different gene functional groups inherited from each of the ancient people. The Papuan genomes demonstrate a relative prevalence of Neanderthal alleles in genes responsible for the regulation of transcription and neurogenesis. The enrichment of specific functional groups with Denisovan alleles is less pronounced; these groups are responsible for bone and tissue remodeling. This analysis shows that introgression of alleles from Neanderthals and Denisovans to Papuans occurred independently and retention of these alleles may carry specific adaptive advantages.
ONE SIZE (DOES NOT) FIT ALL: EVIDENCE OF SIMILARITIES AND DIFFERENCES BETWEEN PRODUCT INNOVATION MANAGEMENT IN HIGH- AND LOW-TECH MANUFACTURING FIRMS
Authors: KEARNEY CLAUDINE , McCARTHY KILLIAN J. , HUIZINGH EELKO K. R. E.
Published: March 2018

Most literature on product innovation management (PIM) has developed through a small number of high-tech manufacturer studies. It is assumed that, for other types of firms, ‘one size fits all’. This research addresses this issue by investigating PIM in both high- and low-tech firms. Building on Cormican and O’Sullivan’s (2004) Best Practice Model (BPM) this paper analyzes PIM of 112 high-tech in comparison to 184 low-tech manufacturing firms in the Netherlands. The empirical results show significant sector-level differences in the impact of the five constructs and, in some cases, insignificant and even opposite effects. Our findings show that one size does not fit all, and blindly following the theory can not only have a suboptimal effect but may even have a negative effect. Furthermore, there are some similarities in high- and low-tech PIM, for example Communication and Collaboration is the only construct that is positive and significant in all cases. The implications of these results in relation to high- and low-tech manufacturing firms are discussed.
Identifying Policy Measures for Reducing Expected Air Pollution Across Israel and Analyzing their Expected Effects
Authors: Lavee Doron , Menachem Ofer
Published: March 2018

This study analyzes the effects of setting policy measures for reducing the emission of air pollutants. The study focuses on five main air pollutants, PM[Formula: see text], PM[Formula: see text], O3, NO2 and SO2. Appropriate policy measures for improving air quality were determined based on data on current and expected air quality obtained by dispersion models, as well as on expected emission inventories for the target years 2015 and 2020. The scenario anticipated to result from implementing these measures was also analyzed by dispersion models. The findings indicate that “business as usual” (BAU) policy measures are not sufficient for meeting the target values for the target years. This study identifies additional policy measures that can considerably improve air quality. However, the concentrations of several pollutants are still expected to exceed their target values in many areas, requiring an even greater expansion of the proposed measures for their reduction.
Green’s Function and Eshelby’s Tensor Based on Mindlin’s 2nd Gradient Model: An Explicit Study of Cylindrical Inclusion Case
Authors: Selmi Abdellatif
Published: March 2018

Based on Mindlin’s 2nd gradient model that involves two length-scale parameters, Green’s function, Eshelby tensor and Eshelby-like tensor for an inclusion of arbitrary shape are derived. It is proved that the Eshelby tensor consists of two parts: the classical Eshelby tensor and a gradient part including the length-scale parameters, which enable the interpretation of the size effect. When the strain gradient is not taken into account, the obtained Green’s function and Eshelby tensor reduce to its analogue based on the classical elasticity. For the cylindrical inclusion case, the Eshelby tensor in and outside the inclusion, the volume average of the gradient part and the Eshelby-like tensor are explicitly obtained. Unlike the classical Eshelby tensor, the results show that the components of the new Eshelby tensor vary with the position and the inclusion dimensions. It is demonstrated that the contribution of the gradient part should not be neglected.
China’s Engagement in the Danube Sub-Region: Opportunities and Challenges
Authors: Long Jing
Published: March 2018

Encouraged by China’s “[Formula: see text] Cooperation” mechanism and the “Belt and Road Initiative (BRI)”, many Central and Eastern European countries (CEECs) expect more Chinese engagement in the development of the Danube sub-region. Located in the Danube sub-region, CEECs share common development needs in waterway transport, environmental protection, energy supply and ecological conservation, all of which are great opportunities for China. Nevertheless, China is still faced with some challenges when participating in the Danube sub-regional cooperation with the European Union (EU) and CEECs. When exploring the feasibility of cooperation in the sub-region, China needs to strive for strategic synergy with the EU, and in particular the EU Strategy for Danube Region (EUSDR), make full use of the existing sub-regional platforms and mechanisms for better understanding of recent developments as well as regulations and standards implemented in the sub-region, and expand cooperation with countries along the river, in order to better drive the development of the sub-region.
Managing Leadership in the Indo-Pacific: The United States’ South Asia Strategy Revisited
Authors: Yang Xiaoping
Published: March 2018

The United States’ South Asia strategy has been based on the calculation of its overall national security priorities. In practice, when U.S. priorities are at odds with those of other regional powers, Washington tends to adopt a “no-expectations” psychological approach toward its regional partners to avoid disappointment, a technical “de-hyphenation strategy” to improve policy efficiency, and practical cost-benefit analysis to evaluate the effectiveness of its South Asia strategy. However, Washington often has to come to terms with the realities on the ground with regard to its leadership role in South Asia. For the time being, Washington has articulated its strategic objective in South Asia, that is, a regional balance of power in favor of the United States vis-a-vis its perceived competitor, China. Therefore, it has conducted conditional cooperation with Pakistan and Afghanistan on land, and committed support for India on security issues in the Indian Ocean, so as to hedge against China’s growing presence in South Asia. The enhancement of U.S.-India defense and security cooperation has fueled China’s suspicion of India’s intention to join the U.S.-led coalition against it. By the logic of balance of power, the United States will continue to regard India as a strategic counterweight to China, which is likely to increase the possibility of strategic tensions and conflicts between China and India that may finally entangle the United States.
Liquefaction of loess landslides as a consequence of irrigation
Authors: Peng Jianbing , Zhuang Jianqi , Wang Gonghui , Dai Fuchu , Zhang Fanyu , Huang Weiliang , Xu Qiang
Published: March 2018

Most landslides on the Loess Tableland (Shaanxi, China) are of the sliding-flow type, with long run-out distances. These landslides, which tend to be triggered by irrigation, result in loss of life and damage to infrastructure. In order to reveal the characteristics and mechanisms of sliding-flow landslides, field investigations, surveys and indoor tests, including consolidated undrained triaxial tests and ring-shear tests, were conducted. The apparent friction of sliding-flow loess landslides triggered by irrigation in the study area ranged from 0.01 to 0.25, with a mean of 0.159. These values are lower than those associated with the landslides triggered by the Wenchuan Earthquake. The deviation stress decreased to about 99% of its peak value, while the path of the effective stress revealed that the effective normal stress approached zero. Consequently, saturated loess samples were highly liquefiable under consolidated undrained triaxial tests. The pore pressures increased sharply and up to their peak value (mean of 130 kPa), corresponding to 92% of the applied normal stress. The path of effective stress did not reach the failure line. The loose structure and macro-pore content of loess provide the framework for static liquefaction to occur as a consequence of the generation of fine particles.
Failure dynamics of landslide scars on the lower continental slope of the Tyrrhenian Calabrian margin: insights from an integrated morpho-bathymetric and seismic analysis
Authors: Casalbore Daniele , Martorelli Eleonora , Bosman Alessandro , Morelli Eleonora , Latino Chiocci Francesco
Published: March 2018

The collection of high-resolution multibeam bathymetry off the tectonically controlled Tyrrhenian Calabrian margin (southern Tyrrhenian Sea) allowed us to recognize several mass-wasting processes, including shelf-indenting canyons and several landslide scars ranging over different spatial scales. In this paper, we aim to characterize two large submarine landslides (S1 and S2) affecting an area of
c.
7 and 14 km
2
, respectively; both scars occur within water depths of 700–1000 m on slope gradients of 1.5−3°. S1 is interpreted as a disintegrative landslide, because most parts of the related landslide deposits were evacuated from the scar and are not recognizable on the present-day bathymetry, whereas the landslide deposits of S2 are well-preserved and mostly confined within the scar, indicating a different post-failure evolution. Based on the integration of multibeam bathymetry and single-channel seismic profiles, both the landslides are interpreted as translational failures, whereas their different post-failure behaviour has been associated with differences in material properties (inferred by headscarp morphology), depth of their failure plane and frontal confinement. We also suggest that thick contourite deposits recognized in the area may represent an important preconditioning factor for the development of these landslides, similarly to that observed in the nearby Capo Vaticano scar complex.
A Low-Complexity Approach to Distributed Cooperative Caching with Geographic Constraints
Authors: Avrachenkov Konstantin , Goseling Jasper , Serbetci Berksan
Published: March 2018

We consider caching in cellular networks in which each base station is equipped with a cache that can store a limited number of files. The popularity of the files is known and the goal is to place files in the caches such that the probability that a user at an arbitrary location in the plane will find the file that she requires in one of the covering caches is maximized.

We develop distributed asynchronous algorithms for deciding which contents to store in which cache. Such cooperative algorithms require communication only between caches with overlapping coverage areas and can operate in asynchronous manner. The development of the algorithms is principally based on an observation that the problem can be viewed as a potential game. Our basic algorithm is derived from the best response dynamics. We demonstrate that the complexity of each best response step is independent of the number of files, linear in the cache capacity and linear in the maximum number of base stations that cover a certain area. Then, we show that the overall algorithm complexity for a discrete cache placement is polynomial in both network size and catalog size. In practical examples, the algorithm converges in just a few iterations. Also, in most cases of interest, the basic algorithm finds the best Nash equilibrium corresponding to the global optimum. We provide two extensions of our basic algorithm based on stochastic and deterministic simulated annealing which find the global optimum.

Finally, we demonstrate the hit probability evolution on real and synthetic networks numerically and show that our distributed caching algorithm performs significantly better than storing the most popular content, probabilistic content placement policy and Multi-LRU caching policies.
TriAL
Authors: Libkin Leonid , Reutter Juan L. , Soto Adrián , Vrgoč Domagoj
Published: March 2018

Navigational queries over RDF data are viewed as one of the main applications of graph query languages, and yet the standard model of graph databases—essentially labeled graphs—is different from the triples-based model of RDF. While encodings of RDF databases into graph data exist, we show that even the most natural ones are bound to lose some functionality when used in conjunction with graph query languages. The solution is to work directly with triples, but then many properties taken for granted in the graph database context (e.g., reachability) lose their natural meaning.

Our goal is to introduce languages that work directly over triples and are closed, i.e., they produce sets of triples, rather than graphs. Our basic language is called TriAL, or Triple Algebra: it guarantees closure properties by replacing the product with a family of join operations. We extend TriAL with recursion and explain why such an extension is more intricate for triples than for graphs. We present a declarative language, namely a fragment of datalog, capturing the recursive algebra. For both languages, the combined complexity of query evaluation is given by low-degree polynomials. We compare our language with previously studied graph query languages such as adaptations of XPath, regular path queries, and nested regular expressions; many of these languages are subsumed by the recursive triple algebra. We also provide an implementation of recursive TriAL on top of a relational query engine, and we show its usefulness by running a wide array of navigational queries over real-world RDF data, while at the same time testing how our implementation compares to existing RDF systems.
ProgressER
Authors: Altowim Yasser , Kalashnikov Dmitri V. , Mehrotra Sharad
Published: March 2018

Entity resolution (ER) is the process of identifying which entities in a dataset refer to the same real-world object. In relational ER, the dataset consists of multiple entity-sets and relationships among them. Such relationships cause the resolution of some entities to influence the resolution of other entities. For instance, consider a relational dataset that consists of a set of research paper entities and a set of venue entities. In such a dataset, deciding that two research papers are the same may trigger the fact that their venues are also the same. This article proposes a progressive approach to relational ER, named ProgressER, that aims to produce the highest quality result given a constraint on the resolution budget, specified by the user. Such a progressive approach is useful for many emerging analytical applications that require low latency response (and thus cannot tolerate delays caused by cleaning the entire dataset) and/or in situations where the underlying resources are constrained or costly to use. To maximize the quality of the result, ProgressER follows an adaptive strategy that periodically monitors and reassesses the resolution progress to determine which parts of the dataset should be resolved next and how they should be resolved. More specifically, ProgressER divides the input budget into several resolution windows and analyzes the resolution progress at the beginning of each window to generate a resolution plan for the current window. A resolution plan specifies which blocks of entities and which entity pairs within blocks need to be resolved during the plan execution phase of that window. In addition, ProgressER specifies, for each identified pair of entities, the order in which the similarity functions should be applied on the pair. Such an order plays a significant role in reducing the overall cost because applying the first few functions in this order might be sufficient to resolve the pair. The empirical evaluation of ProgressER demonstrates its significant advantage in terms of progressiveness over the traditional ER techniques for the given problem settings.
A Fine-grained Event-based Modem Power Model for Enabling In-depth Modem Energy Drain Analysis
Authors: Chen Xiaomeng , Meng Jiayi , Hu Y. Charlie , Gupta Maruti , Hasholzner Ralph , Ekambaram Venkatesan Nallampatti , Singh Ashish , Srikanteswara Srikathyayani
Published: March 2018

Cellular modems enable ubiquitous Internet connectivities to modern smartphones, but in doing so they become a major contributor to the smartphone energy drain. Understanding modem energy drain requires a detailed power model. The prior art, an RRC-state based power model, was developed primarily to model the modem energy drain of application data transfer. As such, it serves well its original purpose, but is insufficient to study detailed modem behavior, e.g., activities in the control plane.

In this paper, we propose a new methodology of modeling modem power draw behavior at the event-granularity, and develop to our knowledge the first fine-grained modem power model that captures the power draw of all LTE modem radio-on events in different RRC modes. Second, we quantitatively demonstrate the advantages of the new model over the state-based power model under a wide variety of context via controlled experiments. Finally, using our fine-grained modem power model, we perform the first detailed modem energy drain in-the-wild study involving 12 Nexus 6 phones under normal usage by 12 volunteers spanning a total of 348 days. Our study provides the first quantitative analysis of energy drain due to modem control activities in the wild and exposes their correlation with context such as location and user mobility.
Tied Kronecker Product Graph Models to Capture Variance in Network Populations
Authors: Moreno Sebastian , Neville Jennifer , Kirshner Sergey
Published: March 2018

Much of the past work on mining and modeling networks has focused on understanding the observed properties of
single
example graphs. However, in many real-life applications it is important to characterize the structure of
populations
of graphs. In this work, we analyze the distributional properties of probabilistic generative graph models (PGGMs) for network populations. PGGMs are statistical methods that model the network distribution and match common characteristics of real-world networks. Specifically, we show that most PGGMs cannot reflect the natural variability in graph properties observed
across
multiple networks because their edge generation process assumes independence among edges. Then, we propose the
mixed Kronecker Product Graph Model
(mKPGM), a scalable generalization of KPGMs that uses tied parameters to increase the variability of the sampled networks, while preserving the edge probabilities in expectation. We compare mKPGM to several other graph models. The results show that learned mKPGMs accurately represent the characteristics of real-world networks, while also effectively capturing the natural variability in network structure.
Continuous-Time User Modeling in Presence of Badges
Authors: Khodadadi Ali , Hosseini Seyed Abbas , Tavakoli Erfan , Rabiee Hamid R.
Published: March 2018

User modeling plays an important role in delivering customized web services to the users and improving their engagement. However, most user models in the literature do not explicitly consider the temporal behavior of users. More recently, continuous-time user modeling has gained considerable attention and many user behavior models have been proposed based on temporal point processes. However, typical point process-based models often considered the impact of peer influence and content on the user participation and neglected other factors. Gamification elements are among those factors that are neglected, while they have a strong impact on user participation in online services. In this article, we propose interdependent multi-dimensional temporal point processes that capture the impact of badges on user participation besides the peer influence and content factors. We extend the proposed processes to model user actions over the community-based question and answering websites, and propose an inference algorithm based on Variational-Expectation Maximization that can efficiently learn the model parameters. Extensive experiments on both synthetic and real data gathered from Stack Overflow show that our inference algorithm learns the parameters efficiently and the proposed method can better predict the user behavior compared to the alternatives.