bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbulent flow of finite-size spherical particles in channels with viscous hyper-elastic walls
Authors: Ardekani M. N. , Rosti M. E. , Brandt L.
Published: June 2019

We study single-phase and particle-laden turbulent channel flows bounded by two incompressible hyper-elastic walls with different deformability at bulk Reynolds number $5600$. The solid volume fraction of finite-size neutrally buoyant rigid spherical particles considered is $10\,\%$. The elastic walls are assumed to be of a neo-Hookean material. A fully Eulerian formulation is employed to model the elastic walls together with a direct-forcing immersed boundary method for the coupling between the fluid and the particles. The data show a significant drag increase and the enhancement of the turbulence activity with growing wall elasticity for both the single-phase and particle-laden flows when compared with the single-phase flow over rigid walls. Drag reduction and turbulence attenuation is obtained, on the other hand, with highly elastic walls when comparing the particle-laden flow with the single-phase flow for the same wall properties; the opposite effect, drag increase, is observed upon adding particles to the flow over less elastic walls. This is explained by investigating the near-wall turbulence, where the strong asymmetry in the magnitude of the wall-normal velocity fluctuations (favouring positive $v^{\prime }$), is found to push the particles towards the channel centre. The particle layer close to the wall contributes to turbulence production by increasing the wall-normal velocity fluctuations, so that in the absence of this layer, smaller wall deformations and in turn turbulence attenuation is observed. For a moderate wall elasticity, we increase the particle volume fraction up to $20\,\%$ and find that particle migration away from the wall is the cause of turbulence attenuation with respect to the flow over rigid walls. However, for this higher volume fractions, the particle induced stress compensates for the decreasing Reynolds shear stress, resulting in a higher overall drag for the case with elastic walls. The effect of the wall elasticity on the overall drag reduces significantly with increasing particle volume fraction.
Making sense of work: finding meaning in work narratives
Authors: Scott Kimberly S.
Published: June 2019

This study examined how individuals make sense of their work narratives – autobiographical stories about their work lives – and the implications for individual well-being. A mixed methods approach was used to investigate relationships between meaning making, pathways to meaningfulness, job characteristics, job involvement, and psychological well-being. Survey responses and narrative themes from life story interviews were collected from 119 adults. A narrative coding scheme was developed to identify pathways to meaningful work. Results show that people made sense of their work lives most often by constructing themes about personal agency. The findings support prior research suggesting that socioeconomic factors, access to resources, and working conditions increase the likelihood of finding and benefiting from meaningful work. For individuals wishing to find meaning in their work, job design characteristics (e.g., decision authority, skill discretion), and developing a sense of agency can be levers for fostering meaning and well-being.
The electoral implications of politically irrelevant cues under demanding electoral systems
Authors: Muraoka Taishi
Published: June 2019

Cognitively demanding electoral systems increase the chance that voters make their choices based on politically irrelevant cues. To illustrate this argument, I analyze the effect of candidate name complexity—a visual cue that contains no politically meaningful information—in Japan, where voters need to write their preferred candidate's name on a blank ballot paper. I find that when electoral systems require voters to weigh a large number of candidates and simultaneously reduce the usefulness of partisan cues, candidates with more complex names tend to receive lower vote shares. By contrast, under less cognitively demanding systems, candidate name complexity has no effect on election outcomes. These findings have important implications for the debate on the “best” electoral system design.
Improving Near‐Surface Retrievals of Surface Humidity Over the Global Open Oceans From Passive Microwave Observations
Authors: Roberts J. Brent , Clayson C. A. , Robertson F. R.
Published: June 2019

Ocean evaporative fluxes are a critical component of the Earth's energy and water cycle, but their estimation remains uncertain. Near‐surface humidity is a required input to bulk flux algorithms that relate mean surface values to the turbulent fluxes. Several satellite‐derived turbulent flux products have been developed over the last decade that utilize passive microwave imager observations to estimate the surface humidity. It is known, however, that these estimates tend to diverge from one another and from in situ observations. Analysis of current state‐of‐the‐art satellite estimates provided herein reveals that regional‐scale biases in these products remain significant. Investigations reveal a link between the spatial coherency of the observed biases to atmospheric dynamical controls of water vapor vertical stratification, cloud liquid water, and sea surface temperature. This information is used to develop a simple state‐dependent bias correction that results in more consistent ocean surface humidity estimates. A principal conclusion is that further improvements to ocean near‐surface humidity estimation using microwave radiometers requires incorporation of prior information on water vapor stratification and sea surface temperature.
Simulation of Remote Sensing of Clouds and Humidity From Space Using a Combined Platform of Radar and Multifrequency Microwave Radiometers
Authors: Jiang Jonathan H. , Yue Qing , Su Hui , Kangaslahti Pekka , Lebsock Matthew , Reising Steven , Schoeberl Mark , Wu Longtao , Herman Robert L.
Published: June 2019

This study presents a simulated simultaneous retrieval of mass mean cloud ice particle effective diameter, ice water content, water vapor, and temperature profiles using a combination of a 94‐GHz cloud radar and multifrequency (118, 183, 240, 310, 380, 664, and 850 GHz) millimeter‐ and submillimeter‐wave radiometers from a space platform. The retrieval capabilities and uncertainties of the combined radar and microwave radiometers are quantified. We show that this combined active and passive remote sensing approach with SmallSat technologies addresses a gap in the current state‐of‐the‐art remote sensing measurements of ice cloud properties, especially deriving vertical profiles of ice cloud particle sizes in the atmosphere together with the ambient thermodynamic conditions. Therefore, this new approach can serve as a plausible candidate for future missions that target cloud and precipitation processes to improve weather forecasts and climate predictions.
Spatial and Temporal Characteristics of Asymmetries in Tropical Cyclones
Authors: Guo Jiahua , Kuang Zhiming
Published: June 2019

Azimuthally asymmetric perturbations are important to hurricanes because they can influence the track, structure, and intensity of a hurricane. In this work, we applied space‐time spectral analysis on both dynamic and thermodynamic fields of these perturbations and found two distinct power peaks in most of the fields. We obtained the structure of each mode by first filtering the fields through a frequency‐wavenumber spectral window selected for each mode and then regressing these fields on an index based on the filtered radar reflectivity. We found that the fast‐propagating wave is dominated by perturbations near the eyewall, and its structure is similar to that of the unstable mixed vortex Rossby inertia gravity wave. The other peak corresponds to a slow‐propagating wave that has comparable perturbations in and beyond the eyewall. The slow wave has a retrograde intrinsic propagating speed and has a vertical structure that resembles that of convectively coupled waves.
Constraints on Seismic Anisotropy in the Mantle Transition Zone From Long‐Period SS Precursors
Authors: Huang Quancheng , Schmerr Nicholas , Waszek Lauren , Beghein Caroline
Published: June 2019

The mantle transition zone (MTZ) of Earth is demarcated by solid‐to‐solid phase changes of the mineral olivine that produce seismic discontinuities at 410 and 660‐km depths. Mineral physics experiments predict that wadsleyite can have strong single‐crystal anisotropy at the pressure and temperature conditions of the MTZ. Thus, significant seismic anisotropy is possible in the upper MTZ where lattice‐preferred orientation of wadsleyite is produced by mantle flow. Here, we use a body wave method, SS precursors, to study the topography change and seismic anisotropy near the MTZ discontinuities. We stack the data to explore the azimuthal dependence of travel‐times and amplitudes of SS precursors and constrain the azimuthal anisotropy in the MTZ. Beneath the central Pacific, we find evidence for ~4% anisotropy with a SE fast direction in the upper mantle and no significant anisotropy in the MTZ. In subduction zones, we observe ~4% anisotropy with a trench‐parallel fast direction in the upper mantle and ~3% anisotropy with a trench‐perpendicular fast direction in the MTZ. The transition of fast directions indicates that the lattice‐preferred orientation of wadsleyite induced by MTZ flow is organized separately from the flow in the upper mantle. Global azimuthal stacking reveals ~1% azimuthal anisotropy in the upper mantle but negligible anisotropy (<1%) in the MTZ. Finally, we correct for the upper mantle and MTZ anisotropy structures to obtain a new MTZ topography model. The anisotropy correction produces ±3 km difference and therefore has minor overall effects on global MTZ topography.
Near‐Earth Solar Wind Forecasting Using Corotation From L5: The Error Introduced By Heliographic Latitude Offset
Authors: Owens M. J. , Riley P. , Lang M. , Lockwood M.
Published: June 2019

Routine in situ solar wind observations from L5, located 60° behind Earth in its orbit, would provide a valuable input to space weather forecasting. One way to utilize such observations is to assume that the solar wind is in perfect steady state over the 4.5 days it takes the Sun to rotate 60°, and thus, near‐Earth solar wind in 4.5 days time would be identical to that at L5 today. This corotation approximation is most valid at solar minimum when the solar wind is slowly evolving. Using STEREO data, it has been possible to test L5‐corotation forecasting for a few months mostly at solar minimum, but the various contributions to forecast error cannot be disentangled. This study uses 40+ years of magnetogram‐constrained solar wind simulations to isolate the effect of latitudinal offset between L5 and Earth due to the inclination of the ecliptic plane to the solar rotational equator. Latitudinal offset error is found to be largest at solar minimum, due to the latitudinal ordering of solar wind structure. It is also a strong function of time of year: maximum at the solstices and very low at equinoxes. At solstice, the latitudinal offset alone means L5‐corotation forecasting is expected to be less accurate than numerical solar wind models, even before accounting for time‐dependent solar wind structures. Thus, a combination of L5‐corotation and numerical solar wind modeling may provide the best forecast. These results also highlight that three‐dimensional solar wind structure must be accounted for when performing solar wind data assimilation.
Genome-wide methylation in alcohol use disorder subjects: implications for an epigenetic regulation of the cortico-limbic glucocorticoid receptors (NR3C1)
Authors: Gatta Eleonora , Grayson Dennis R. , Auta James , Saudagar Vikram , Dong Erbo , Chen Ying , Krishnan Harish R. , Drnevich Jenny , Pandey Subhash C. , Guidotti Alessandro
Published: June 2019

Environmental factors, including substance abuse and stress, cause long-lasting changes in the regulation of gene expression in the brain via epigenetic mechanisms, such as DNA methylation. We examined genome-wide DNA methylation patterns in the prefrontal cortex (PFC, BA10) of 25 pairs of control and individuals with alcohol use disorder (AUD), using the Infinium®MethylationEPIC BeadChip. We identified 5254 differentially methylated CpGs (pnominal < 0.005). Bioinformatic analyses highlighted biological processes containing genes related to stress adaptation, including the glucocorticoid receptor (encoded byNR3C1). Considering that alcohol is a stressor, we focused our attention on differentially methylated regions of theNR3C1gene and validated the differential methylation of several genes in the NR3C1 network. Chronic alcohol drinking results in a significant increased methylation of theNR3C1exon variant 1H, with a particular increase in the levels of 5-hydroxymethylcytosine over 5-methylcytosine. These changes in DNA methylation were associated with reduced NR3C1 mRNA and protein expression levels in PFC, as well as other cortico-limbic regions of AUD subjects when compared with controls. Furthermore, we show that the expression of several stress-responsive genes (e.g.,CRF,POMC, andFKBP5) is altered in the PFC of AUD subjects. These stress-response genes were also changed in the hippocampus, a region that is highly susceptible to stress. These data suggest that alcohol-dependent aberrant DNA methylation ofNR3C1and consequent changes in other stress-related genes might be fundamental in the pathophysiology of AUD and lay the groundwork for treatments targeting the epigenetic mechanisms regulatingNR3C1in AUD.
Virome heterogeneity and connectivity in waterfowl and shorebird communities
Authors: Wille Michelle , Shi Mang , Klaassen Marcel , Hurt Aeron C , Holmes Edward C
Published: June 2019

Models of host-microbe dynamics typically assume a single-host population infected by a single pathogen. In reality, many hosts form multi-species aggregations and may be infected with an assemblage of pathogens. We used a meta-transcriptomic approach to characterize the viromes of nine avian species in the Anseriformes (ducks) and Charadriiformes (shorebirds). This revealed the presence of 27 viral species, of which 24 were novel, including double-stranded RNA viruses (Picobirnaviridae and Reoviridae), single-stranded RNA viruses (Astroviridae, Caliciviridae, Picornaviridae), a retro-transcribing DNA virus (Hepadnaviridae), and a single-stranded DNA virus (Parvoviridae). These viruses comprise multi-host generalist viruses and those that are host-specific, indicative of both virome connectivity (host sharing) and heterogeneity (host specificity). Virome connectivity was apparent in two well described multi-host virus species -avian coronavirus and influenza A virus- and a novel Rotavirus species that were shared among some Anseriform species, while virome heterogeneity was reflected in the absence of viruses shared between Anseriformes and Charadriiformes, as well as differences in viral abundance and alpha diversity among species. Overall, we demonstrate complex virome structures across host species that co-exist in multi-species aggregations.
Correction: Waldenström macroglobulinemia treatment algorithm 2018
Authors: Gertz Morie A.
Published: June 2019

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Two QTLs controlling Clubroot resistance identified from Bulked Segregant Sequencing in Pakchoi (Brassica campestris ssp. chinensis Makino)
Authors: Zhu Hongfang , Zhai Wen , Li Xiaofeng , Zhu Yuying
Published: June 2019

Clubroot, caused by Plasmodiophora Brassicae, is a serious soil-borne disease in worldwide. In recent years, progression of clubroot is rapid and serious in Shanghai, China. In this study, The inheritance of clubroot resistance (CR) were determined in pakchoi using F2 segregation population that were developed by crossing highly resistant line ‘CR38’ and susceptible line ‘CS22’. Two novel QTLs, qBrCR38-1 and qBrCR38-2, was identified by BSA-seq (Bulked Segregant Sequencing) resistant to P. brassicae physiological race 7. Two significant peak qBrCR38-1 and qBrCR38-2 were observed by three statistical methods between interval of 19.7–20.6 Mb in chromosome A07 and 20.0–20.6 Mb in chromosome A08, respectively. In addition, Polymorphic SNPs identified within target regions were converted to kompetitive allele-specific PCR (KASP) assays. In target regions of qBrCR38-1 and qBrCR38-2, there were twenty SNP sites identified, eleven KASP markers of which are significantly associated to CR (P < 0.05). Seven candidate genes were identified and found to be involved in disease resistance (TIR-NBS-LRR proteins), defense responses of bacterium and fungi and biotic/abiotic stress response in the target regions harboring the two QTLs. Two novel QTLs and candidate genes identified from the present study provide insights into the genetic mechanism of CR in B.rapa, and the associated SNPs can be effectively used for marker-assisted breeding.
Transcriptomic analysis of 3D Cardiac Differentiation of Human Induced Pluripotent Stem Cells Reveals Faster Cardiomyocyte Maturation Compared to 2D Culture
Authors: Branco Mariana A. , Cotovio João P. , Rodrigues Carlos A. V. , Vaz Sandra H. , Fernandes Tiago G. , Moreira Leonilde M. , Cabral Joaquim M. S. , Diogo Maria Margarida
Published: June 2019

Human induced pluripotent stem cells (hiPSCs) represent an almost limitless source of cells for disease modelling and drug screening applications. Here we established an efficient and robust 3D platform for cardiomyocyte (CMs) production from hiPSCs, solely through small-molecule-based temporal modulation of the Wnt signalling, which generates more than 90% cTNT+ cells. The impact of performing the differentiation process in 3D conditions as compared to a 2D culture system, was characterized by transcriptomic analysis by using data collected from sequential stages of 2D and 3D culture. We highlight that performing an initial period of hiPSC aggregation before cardiac differentiation primed hiPSCs towards an earlier mesendoderm lineage differentiation, via TGF-β/Nodal signaling stabilization. Importantly, it was also found that CMs in the 3D microenvironment mature earlier and show an improved communication system, which we suggested to be responsible for a higher structural and functional maturation of 3D cardiac aggregates.
Tolvaptan activates the Nrf2/HO-1 antioxidant pathway through PERK phosphorylation
Authors: Fujiki Tamami , Ando Fumiaki , Murakami Kana , Isobe Kiyoshi , Mori Takayasu , Susa Koichiro , Nomura Naohiro , Sohara Eisei , Rai Tatemitsu , Uchida Shinichi
Published: June 2019

Tolvaptan, a vasopressin type 2 receptor antagonist initially developed to increase free-water diuresis, has been approved for the treatment of autosomal dominant polycystic kidney disease in multiple countries. Furthermore, tolvaptan has been shown to improve the renal functions in rodent models of chronic kidney disease (CKD); however, the underlying molecular mechanisms remain unknown. CKD is characterized by increased levels of oxidative stress, and an antioxidant transcription factor—nuclear factor erythroid 2-related factor 2 (Nrf2)—has been gaining attention as a therapeutic target. Therefore, we investigated the effects of tolvaptan and a well-known Nrf2 activator, bardoxolone methyl (BARD) on Nrf2. To determine the role of tolvaptan, we used a renal cortical collecting duct (mpkCCD) cell line and mouse kidneys. Tolvaptan activated Nrf2 and increased mRNA and protein expression of antioxidant enzyme heme oxygenase-1 (HO-1) in mpkCCD cells and the outer medulla of mouse kidneys. In contrast to BARD, tolvaptan regulated the antioxidant systems via a unique mechanism. Tolvaptan activated the Nrf2/HO-1 antioxidant pathway through phosphorylation of protein kinase RNA-like endoplasmic reticulum kinase (PERK). As a result, tolvaptan and BARD could successfully generate synergistic activating effects on Nrf2/HO-1 antioxidant pathway, suggesting that this combination therapy can contribute to the treatment of CKD.
Seeking Maxwell’s Demon in a non-reciprocal quantum ring
Authors: Manaselyan Aram , Luo Wenchen , Braak Daniel , Chakraborty Tapash
Published: June 2019

A non-reciprocal quantum ring, where one arm of the ring contains the Rashba spin-orbit interaction but not in the other arm, is found to posses very unique electronic properties. In this ring the Aharonov-Bohm oscillations are totally absent. That is because in a magnetic field the electron stays in the non-Rashba arm, while it resides in the Rashba arm for zero (or negative) magnetic field. The average kinetic energy in the two arms of the ring are found to be very different. It also reveals different “spin temperature” in the two arms of the non-reciprocal ring. The electrons are sorted according to their spins in different regions of the ring by switching on and off (or reverse) the magnetic field, thereby creating order without doing work on the system. This resembles the action of a demon in the spirit of Maxwell’s original proposal, exploiting a non-classical internal degree of freedom. Our demon clearly demonstrates some of the required features on the nanoscale.
Hybrid-state free precession in nuclear magnetic resonance
Authors: Assländer Jakob , Novikov Dmitry S. , Lattanzi Riccardo , Sodickson Daniel K. , Cloos Martijn A.
Published: June 2019

The dynamics of large spin-1/2 ensembles are commonly described by the Bloch equation, which is characterized by the magnetization’s non-linear response to the driving magnetic field. Consequently, most magnetic field variations result in non-intuitive spin dynamics, which are sensitive to small calibration errors. Although simplistic field variations result in robust spin dynamics, they do not explore the richness of the system’s phase space. Here, we identify adiabaticity conditions that span a large experiment design space with tractable dynamics. All dynamics are trapped in a one-dimensional subspace, namely in the magnetization’s absolute value, which is in a transient state, while its direction adiabatically follows the steady state. In this hybrid state, the polar angle is the effective drive of the spin dynamics. As an example, we optimize this drive for robust and efficient quantification of spin relaxation times and utilize it for magnetic resonance imaging of the human brain.
Straightforward chemo- and stereoselective fluorocyclopropanation of allylic alcohols: exploiting the electrophilic nature of the not so elusive fluoroiodomethyllithium
Authors: Colella Marco , Tota Arianna , Großjohann Angela , Carlucci Claudia , Aramini Andrea , Sheikh Nadeem S. , Degennaro Leonardo , Luisi Renzo
Published: June 2019

The not so elusive carbenoid fluoroiodomethyllithium disclosed its electrophilic nature in an unprecedented direct and stereoselective fluorocyclopropanation of allylic alcohols.
Disulfide phosphatidylcholines: alternative phospholipids for the preparation of functional liposomes
Authors: Du Yawei , He Wei , Zhou Wenya , Li Xinsong
Published: June 2019

Disulfide phosphatidylcholine-based liposomes can be triggered and completely destroyed in a reductive tumor microenvironment resulting in a fast release of encapsulated drugs.
Variation of nuclearity in NiII complexes of a Schiff base ligand: crystal structures and magnetic studies
Authors: Ghosh Tanmoy Kumar , Mahapatra Prithwish , Jana Subrata , Ghosh Ashutosh
Published: June 2019

Four NiII complexes have been synthesized by changing the reaction conditions and stoichiometry of the reactants. The magnetic coupling in the NiII4 complex is ferromagnetic whereas that in the NiII6 complex is antiferromagnetic.
Snowball formation for Cs+ solvation in molecular hydrogen and deuterium
Authors: Ortiz de Zárate Josu , Bartolomei Massimiliano , González-Lezana Tomás , Campos-Martínez José , Hernández Marta I. , Pérez de Tudela Ricardo , Hernández-Rojas Javier , Bretón José , Pirani Fernando , Kranabetter Lorenz , Martini Paul , Kuhn Martin , Laimer Felix , Scheier Paul
Published: June 2019

Features of the solvation of Cs+ by H2 or D2 are unveiled by means of a combined experimental and computational work.
Mechanistic study on Cu-catalyzed CO2 electroreduction into CH4 at simulated low overpotentials based on an improved electrochemical model
Authors: Ou Lihui , Chen Junxiang , Chen Yuandao , Jin Junling
Published: June 2019

A CO coverage-dependent electrochemical model is firstly applied to Cu-catalyzed CO2 electroreduction into CH4 production at low overpotentials.
The mechanical and thermal properties of MoS2–WSe2 lateral heterostructures
Authors: Qin Huasong , Pei Qing-Xiang , Liu Yilun , Zhang Yong-Wei
Published: June 2019

We investigate the mechanical and thermal transport properties of MoS2–WSe2 lateral heterostructures using molecular dynamics simulations.
Deciphering the grounds of the suitability of acylhydrazones as efficient photoswitches
Authors: Moreno Miquel , Gelabert Ricard , Lluch José M.
Published: June 2019

Calculations on several acylhydrazones are carried out to explain their diverse photochemistry experimentally observed. Results disclose the role of the intramolecular proton transfer or the loss of the azidic proton in the large Stokes shift.
Impact of ferrous iron dosing on iron and phosphorus solids speciation and transformation in a pilot scale membrane bioreactor
Authors: Wu Hao , Wang Yuan , Ikeda-Ohno Atsushi , Miller Christopher J. , Waite T. David
Published: June 2019

Dosing of a pilot scale MBR with a ferrous salt for P removal results in a mix of FePO4(s)and P adsorbed to amorphous iron oxyhydroxides. Increase in the proportion of FePO4(s)is desired given the higher ratio of P : Fe in the biosolids produced.
Towards a spectroscopic protocol for unambiguous detection of quantum coherence in excitonic energy transport
Authors: Marcus Max , Knee George C. , Datta Animesh
Published: June 2019

We propose a witness for quantum coherence in EET that can be extracted directly from two-pulse pump–probe spectroscopy experimental data.
A proteotranscriptomic study of silk-producing glands from the orb-weaving spiders
Authors: dos Santos-Pinto José Roberto Aparecido , Esteves Franciele Grego , Sialana Fernando J. , Ferro Milene , Smidak Roman , Rares Lucaciu Calin , Nussbaumer Thomas , Rattei Thomas , Bilban Martin , Bacci Júnior Maurício , Palma Mario Sergio , Lübec Gert
Published: June 2019

A proteotranscriptomic approach provides a biochemical basis for understanding the intricate spinning process and complex structural features of spider silk proteins.
Oxygen reduction reaction mechanism on a phosporus-doped pyrolyzed graphitic Fe/N/C catalyst
Authors: Dipojono Hermawan K. , Saputro Adhitya G. , Fajrial Apresio K. , Agusta Mohammad K. , Akbar Fiki T. , Rusydi Febdian , Wicaksono Dedy H. B.
Published: June 2019

The interaction between neighbouring FeN4 and Psubs sites of a P-doped pyrolyzed Fe/N/C catalyst promotes four-electron reduction through associative and dissociative mechanisms.
In situ catalyst exsolution on perovskite oxides for the production of CO and synthesis gas in ceramic membrane reactors
Authors: Dimitrakopoulos Georgios , Ghoniem Ahmed F. , Yildiz Bilge
Published: June 2019

In situ exsolution of nickel nano-particles on both sides of ceramic membrane reactors to accelerate the co-production of CO and synthesis gas through CO2 splitting and CH4 partial oxidation, respectively.
Scalable framework for green large cognitive radio networks
Authors: Daha Belghiti Imane , Berrada Ismail , El Kamili Mohamed
Published: June 2019

Cognitive radio networks (CRNs) have the capacity to be aware of the conditions of their operating environment, and dynamically reconfigure their own characteristics in order to reach the best available performances. These performances may be seriously impacted when the number of users in CRNs grows significantly. This study deals with efficient energy consumption and interference avoidance in large CRNs. To enhance the network lifetime, a new framework combining cognitive hierarchical clustering and the coalitional game is introduced. In this study, a new CRLEACH protocol is proposed and the well‐known LEACH protocol is used in CRNs. The authors prove theoretically that their coalition model with a new strategic learning algorithm leads to Nash equilibrium. Finally, the network performances of their framework are illustrated by numerical results.
Fabrication of soft ferromagnetic multilayer‐structure sensor for measurement of microampere direct currents
Authors: Wang Tao , Wang Bicong , Chen YuYi
Published: June 2019

Quantitative measurements of direct currents are achieved by using multilayer‐structure current sensor (NiFe/Cu/NiFe/Cu/Cr) carrying wide‐frequency alternating currents (20 Hz–100 MHz). It was found that the impedance of the current sensor was reduced in the presence of direct currents, and decreased with increasing direct currents at medium frequency. In addition, the measurement sensitivity increased with increasing the amplitude of the alternating current. The authors also observed that the resistance variation in response to the direct currents was much larger than that of impedance and reactance at medium frequency. This current sensor was capable of measuring the direct current of at least 40 μA, exhibiting a resistance variation of 0.00674 Ω. Consequently, the ferromagnetic multilayer films may serve as a super‐sensitive current sensor for the measurement of currents.
Improving deep image denoising using pseudo‐ground‐truth images
Authors: Jung S.‐W.
Published: June 2019

Deep neural networks, especially convolutional neural networks, have been successfully applied to image denoising tasks. Along with advances in network architectures, many attempts have been made to find an alternative loss function to the widely used L1‐loss and L2‐loss. However, the perception‐distortion tradeoff was recently demonstrated; thus, advanced loss functions such as adversarial loss from generative adversarial networks can only improve the perceptual image quality at the expense of distortion. This Letter shows that distortion can be further decreased when an image denoising network is trained using modified versions of ground‐truth (GT) (defined as pseudo‐ground‐truth (PGT)) images that are obtained by combining the original GT images and initially denoised images. Experimental results show that the proposed denoising network that is trained to predict both PGT and GT images produces denoised images closer to GT images.
Regression analysis of FMCW–LiDAR beat signals for non‐linear chirp mitigation
Authors: Tsuchida H.
Published: June 2019

The performance of a frequency‐modulated continuous wave (FMCW)–light detection and ranging (LiDAR) is severely limited by the inherent non‐linear chirp when laser diodes with direct frequency modulation are used as light sources. To overcome this limitation, optoelectronic feedback techniques were reported for chirp linearisation. The author propose and demonstrate an alternative technique that is based on regression analysis of FMCW–LiDAR beat signals. It is shown that the waveform of the laser frequency modulation accompanied by the non‐linear chirp is analytically expressed in terms of the Fourier series containing both the odd and even harmonics. The analytical expression is utilised in the regression analysis to calculate the unknown distances. A relative accuracy below 1 mm is obtained in the proof‐of‐principle experiment.
Design of compact single‐ended‐to‐balanced filtering power divider with wideband common‐mode suppression
Authors: Li Sai , Wang Xuedao , Wang Jianpeng , Ge Lei
Published: June 2019

A new design of single‐ended‐to‐balanced (SETB) filtering power divider (FPD) with wideband common‐mode (CM) suppression is presented. To effectively realise high suppression of CM noise, a hybrid structure constructed by both the double‐side parallel‐strip line (DSPSL) and a half‐mode defected ground structure (HMDGS) serving as the mid‐inserted conductor plane are adopted. Besides, due to the effect of HMDGS, the rejection of second harmonics for the differential‐mode (DM) transmission is also improved. Meanwhile, by employing two pairs of dual‐mode resonators symmetrically coupled with a stepped‐impedance input feed line and adding a DSPSL stub, wideband‐filtering performance with high selectivity is achieved. For validation, a prototype of the proposed SETB‐FPD centred at 5.9 GHz with a 3‐dB fractional bandwidth (FBW) of 27% is designed, fabricated and measured. Results indicate that the proposed SETB FPD exhibits good performances of high selectivity, wide upper stop band, good isolation between two balanced output ports and 30‐dB suppression of CM noise over the DM pass band.
23 × 12 μm three‐stage amplifier using sub‐threshold active cascode compensation capable of driving very‐large‐load with no‐upper‐limit
Authors: Yan Zhanke , Zhang Chunming , Wang Menghai , Chen Haifeng
Published: June 2019

An ultra‐area‐efficient three‐stage amplifier is proposed by using sub‐threshold active cascade compensation, which is able to drive very‐large or ultra‐large capacitive loads without sacrificing stability and power. Besides, external feed‐forward path and slew‐rate enhancer can significantly improve the large‐signal transient response of the circuit. Designed and verified in 28 nm CMOS technology, the proposed amplifier occupies die area of 0.00028 mm2 and consumes a power of 16.5 µW from 1.05 V supply. In addition, it can provide over 85 dB DC gain and is stable for any load larger than 4 nF, while the size of the entailed compensation capacitance is only 40 fF.
Measurement of temperature and strain simultaneously with high spatial resolution for a long sensing range
Authors: Pradhan Himansu Shekhar , Sahu Prasant Kumar
Published: June 2019

This study presents a Brillouin distributed sensor (BDS) with high spatial resolution for the monitoring of temperature and strain simultaneously. Fourier deconvolution (FD), Fourier regularised deconvolution (FRD), and Fourier regularised denoising deconvolution (FRDD) algorithms have been explored to measure the Brillouin backscattered power using the optical time‐domain reflectometry technique. The improvement of temperature and strain resolutions along with the spatial resolution using the FRDD algorithm is observed for 50 km sensing range. The numerical simulation process of the proposed sensing system has been simultaneously incorporated to extract temperature and strain information. The simulation results show that the temperature and strain resolutions are observed as 5°K and 138 μɛ, respectively, using FRDD compared with the FD algorithm which shows temperature and strain resolutions as 54°K and 1588 μɛ, respectively, at a 50‐km distance. A high spatial resolution of 9 m is observed of the proposed BDS over the sensing range of 50 km using the FRDD algorithm. In addition, the denoising capability of the proposed FRDD algorithm is validated using the experimentally obtained Rayleigh backscattered signal.
Galactocentric acceleration in VLBI analysis
Authors: MacMillan D. S. , Fey A. , Gipson J. M. , Gordon D. , Jacobs C. S. , Krásná H. , Lambert S. B. , Malkin Z. , Titov O. , Wang G. , Xu M. H.
Published: June 2019

Aims. The IVS Working Group on Galactic Aberration (WG8) was established to investigate issues related to incorporating the effect of Galactic aberration in IVS analysis. The circular motion of the solar system barycenter around the Galactic center causes a change in aberration, which in the case of geodetic VLBI observing is over time scales of several decades. One of the specific goals was to recommend a Galactic aberration model to be applied by the IAU ICRF3 working group in the generation of ICRF3 as well as in other IVS analysis. Studies made by working group members have shown that the three-dimensional acceleration vector of the solar system barycenter can be estimated from VLBI delay observations.

Methods. Among the working group members, three methods were used to estimate the acceleration vector. One is to directly estimate the acceleration vector as a global parameter. The second is to estimate the acceleration vector from source proper motions determined from estimated source position time series. A third method estimated a global reference frame scale parameter for each source and derived the acceleration vector from these estimates. The acceleration vector estimate consists of a galactocentric component along with the non-galactocentric components.

Results. The geodetic reference frame VLBI estimates of the galactocentric aberration constant from the different working group members are in the range 5.1–6.4 μas yr−1. These estimates are relatively close to independent estimates of 4.8–5.4 μas yr−1 that can be derived from astrometric measurements of proper motions and parallaxes of masers in the Milky Way galaxy. Based on the most recent geodetic VLBI solutions, we find an upper bound of 0.8 μas yr−1 for the non-galactocentric component of the secular aberration.

Conclusions. The working group made a recommendation only for the galactocentric component of the observed acceleration vector. For the recommended galactocentric aberration constant, the working group chose a geodetic value to be consistent with geodetic VLBI applications. The recommended value 5.8 μas yr−1 was estimated directly in a global solution that used the ICRF3 solution data set: 1979–May 2018.
An Experimental Microstructural Characterization of High-quality, Load-preserved Fabric 1-D Consolidated Kaolinite Samples
Authors: Chow Jun Kang , Li Zhaofeng , Wang Yu-Hsing
Published: June 2019

This paper describes a microstructural characterizations of high-quality, load-preserved fabric 1-D consolidated kaolinite samples, which covers from the beginning stage of clay sample preparation to the final stage of the microstructural analyses. To achieve this goal, a tailor-made oedometer is produced using the 3-D printing technique. First, a uniform kaolinite sample is prepared from a slurry state and then positioned into the 3-D printed oedometer for 1-D consolidation tests. Then, together with the applied loadings, the whole oedometer containing the consolidated kaolinite sample is submerged into the liquid nitrogen. This aims for preparing the dry sample by freeze drying, and at the same time, preserving the fabric associations for the subsequent microstructural characterizations. Afterwards, the sample is cut in half while frozen. An observation plane along the centre with the morphological information preserved is used for the scanning electron microscopy (SEM) analyses, and the remaining section is undergone the mercury intrusion porosimetry to obtain complementary information on the pore-size distribution. By ensuring the position and orientation of the SEM images taken, the number of SEM images, as well as the amount of particles and voids identified are maximized to enhance the statistical representation of the analysed results. In each sample, at least 3000 particles are identified, and the voids are segmented using proper binary images, of which their irregular shapes are further described using an equivalent ellipse. Fabric tensors are used to quantify the directional behaviour of the voids and particles. In addition, the shape evolution of the pores is examined to further understand the associated deformation mechanism. These comprehensive analyses provides quantitative evidences that the loading response of clay under 1-D consolidation is mainly governed by the inter-aggregate pores.
Development of a pore gas pressure transducer used in unsaturated soils at high water content
Authors: Chen Rui , Chen Zhongkui , Ng Charles Wang Wai , Liu Jian
Published: June 2019

Pore gas pressure in soil is an important parameter in many geoscience applications such as evaluating the effects of trapped pore gas pressure on water infiltration through soil mass, optimizing the design of gas extraction wells in landfills and assessing the performance of landfill covers in reducing landfill gas emission. In addition, it has been observed that pore gas pressure affects slope stability in unsaturated soils. However, the pore gas pressure build-up induced by water infiltration is generally ignored in most slope stability analysis by assuming gas pressure to be zero. Therefore, pore gas pressure measurement in soils is crucial to better understand the unsaturated soil behaviour. However, most of current measuring techniques of pore gas pressure are affected by water interruption during the measurement in unsaturated soils, especially at high water content. In this study, a novel gas pressure transducer was developed to measure the pore gas pressure in unsaturated soil within a wide range of water content. The newly developed pore gas pressure transducer mainly consists of an electrical pressure sensor package and an integrated membrane filter which can prevent water leaching through the membrane but allow gas to pass it freely. The performance of the gas pressure transducer was evaluated by a series of permeation tests. The results show that the developed gas pressure transducer has a good repeatability to monitor gas pressure and has a relatively fast response to the gas pressure change in compacted soils. This transducer is able to measure pore gas pressure range of 0~50 kPa of soils within a relatively high range of soil water content.
Characterization of transverse anisotropy in Poisson's ratio using three-point radial deformation measurements
Authors: Toker Nabi Kartal , Büyükyılmaz Kemal Sercan
Published: June 2019

Poisson's ratio (v) of rock specimens can be experimentally determined from radial deformation measurements in an unconfined compression test. This is commonly achieved by mounting a compressometer with diametric or perimetric measurement capability, both of which assume the specimen cross-section remains a circle. If there is anisotropy among the horizontal directions, this assumption fails and measurements err. In this study, a compressometer with three radial deformation measurements is developed. The accuracy of new compressometer in determining the mean of the two v values along the two axes of anisotropy is theoretically investigated, assuming the deformed specimen is an ellipse in cross-section. Then, to capture separate v values along the axes of anisotropy, data from actual tests employing the new device were analysed in two different approaches: Assuming the centroid of the cross-section remains stationary (1) does not produce physically reasonable results. Assuming the specimen moves laterally and v values are constant (2) is possible through a grid search-type optimization algorithm. This results in calculation of the orientation of axes of anisotropy with respect to the compressometer, as well as the corresponding v value.
Estimation of the shear strength of a coarse soil with high fines content by parallel gradation method
Authors: Kouakou N'guessan MoÏse , Cuisinier Olivier , Masrouri Farimah , Lavallée Emmanuel , Le Borgne Tangi
Published: June 2019

The determination of the mechanical properties of soils containing particles larger than the allowable size of standard laboratory equipments is complex. It is indeed necessary to remove the coarsest fraction to carry out the tests. This scalping poses a problem of reliability of the results at the scale of the structure. Parallel gradation is the method commonly used for estimating the shear strength of heterogeneous granular soils from tests on their finer fraction. However, the effect of high fines content on the estimation of shear strength by this method is not well understood. The results of this study show that the parallel gradation method can predict the friction angle of the initial soil with high fines content when the modelled soil has a similar skeleton as the initial soil. However, the cohesion of the initial soil is overestimated.
Study on the Shear Band of Sand with Various Particle Characteristics Using PIV Analysis
Authors: Kajiyama Shintaro , Nakata Yukio , Miyamoto Ryota , Taue Masato
Published: June 2019

The phenomenon of ground undergoing large plastic deformation, leading to collapse, occurs due to the localization of unstable deformation. The investigation of shear band is important in order to understand the destructive phenomenon. Therefore, a series of experiments were conducted on sands with different particle characteristics so that behaviour of the shear band of sand under plane strain compression could be investigated. Specifically, Toyoura sand and two kinds of coral sand, hereafter referred to as coral sand A (with smaller average particle size) and coral sand B (with larger average particle size) were used. The shear band was evaluated using PIV (Partial Image Velocimetry) analysis. As a result, it became clear that the relationship between shear inclination angle and internal friction angle does not hold for the two kinds of coral sand because the shear inclination angle is low. The ratio of the average value of the shear band width to the average grain size at the peak was 10 to 20 times, 7 to 10 times, and 5 to 8 times in the order of Toyoura sand, coral sand A, and coral sand B. The sample standard deviation was 0.1 to 0.9 mm, 0.9 to 1.6 mm, and 1.4 to 1.9 mm.
Shrinkage Curves for Powder and Granular Bentonites
Authors: Wijaya Martin , Leong Eng Choon , Abuel-Naga Hossam
Published: June 2019

Bentonite is one of the most commonly used materials in geotechnical engineering applications especially for isolation purposes due its low permeability and its highly expansive nature. For instance, Geosynthetic Clay Liners (GCL) self-healing ability relies on the swelling properties of the bentonite to close any holes in the GCL while the low permeability of the bentonite serves to reduce the infiltration of leachate to the surrounding soil. However, different types of bentonite have different shrinkage or swelling properties and hence affects the effectiveness of the GCL. A method to assess the wetting/drying induced volume change of the bentonite is through its shrinkage curve. This paper focuses on the shrinkage behaviour of reconstituted granular and powder bentonites which are used in GCL. Photogrammetry method is used to measure the volume change of specimen during drying. The shrinkage curves of the bentonites are then compared with other bentonites from the literature.
An evaluation of contact models for particle-scale simulation of clay
Authors: Bandera Sara , O'Sullivan Catherine , Angioletti-Uberti Stefano , Tangney Paul
Published: June 2019

Geotechnical engineers are well aware that the particle surface chemistry and the pore fluid composition can significantly influence the mechanical behaviour of clay. Reference is often made to the Derjaguin-Landau-Vervey-Overbeek (DLVO) theory, which enables the electrochemical interactions between charged particles to be estimated. Hitherto, the absence of an effective framework for particle-scale simulation of clay has inhibited a direct link between these electrochemical interactions and clay behaviour (e.g. load:deformation response) or fabric (i.e. the development of a disperse or flocculated fabric). Ebrahimi [1] demonstrated the viability of using molecular dynamics simulations where the clay grains are simulated as ellipsoidal particles whose interactions are described by an analytical expression called the Gay-Berne (GB) potential. While promising when compared to other approaches documented in the literature, Ebrahimi's work considered only a single clay mineralogy and did not explicitly account for the pore fluid composition. This paper considers the use of the Gay-Berne potential in particle-scale modelling of clay from a more general perspective. Calibration of the GB model parameters to predict kaolinite particle interactions reveals a lack of generality in Ebrahimi's approach. The Gay-Berne potential cannot simulate situations in which attractive and repulsive interactions co-exist, which lead to the classical “cardhouse” fabric, as is the case of kaolinite particles interacting via an acidic pore fluid.