bluuebunny/crossref_metadata_2025 huggingface dataset:
A Vertex-Aligned Model for Packing 4-Hexagonal Clusters in a Regular Hexagonal Container
Authors: Prvan Marina , Burazin Mišura Arijana , Gecse Zoltan , Ožegović Julije
Published: May 2020

This paper deals with a problem the packing polyhex clusters in a regular hexagonal container. It is a common problem in many applications with various cluster shapes used, but symmetric polyhex is the most useful in engineering due to its geometrical properties. Hence, we concentrate on mathematical modeling in such an application, where using the “bee” tetrahex is chosen for the new Compact Muon Solenoid (CMS) design upgrade, which is one of four detectors used in Large Hadron Collider (LHC) experiment at European Laboratory for Particle Physics (CERN). We start from the existing hexagonal containers with hexagonal cells packed inside, and uniform clustering applied. We compare the center-aligned (CA) and vertex-aligned (VA) models, analyzing cluster rotations providing the increased packing efficiency. We formally describe the geometrical properties of clustering approaches and show that cluster sharing is inevitable at the container border with uniform clustering. In addition, we propose a new vertex-aligned model decreasing the number of shared clusters in the uniform scenario, but with a smaller number of clusters contained inside the container. Also, we describe a non-uniform tetrahex cluster packing scheme in the proposed container model. With the proposed cluster packing solution, it is accomplished that all clusters are contained inside the container region. Since cluster-sharing is completely avoided at the container border, the maximal packing efficiency is obtained compared to the existing models.
Adaptive Partial Image Secret Sharing
Authors: Yan Xuehu , Sun Lei , Lu Yuliang , Yang Guozheng
Published: May 2020

In contrast to encrypting the full secret image in classic image secret sharing (ISS), partial image secret sharing (PISS) only encrypts part of the secret image due to the situation that, in general, only part of the secret image is sensitive or secretive. However, the target part needs to be selected manually in traditional PISS, which is human-exhausted and not suitable for batch processing. In this paper, we introduce an adaptive PISS (APISS) scheme based on salience detection, linear congruence, and image inpainting. First, the salient part is automatically and adaptively detected as the secret target part. Then, the target part is encrypted into n meaningful shares by using linear congruence in the processing of inpainting the target part. The target part is decrypted progressively by only addition operation when more shares are collected. It is losslessly decrypted when all the n shares are collected. Experiments are performed to verify the efficiency of the introduced scheme.
Quasielastic Lepton Scattering off Two-Component Dark Matter in Hypercolor Model
Authors: Beylin Vitaly , Bezuglov Maxim , Kuksa Vladimir , Tretiakov Egor
Published: May 2020

The interaction of high-energy leptons with components of Dark Matter in a hypercolor model is considered. The possibility of detection, using IceCube secondary neutrinos produced by quasielastic scattering of cosmic ray electrons off hidden mass particles, is investigated. The dominant contribution to the cross section results from diagrams with scalar exchanges. A strong dependence of the total cross section on the Dark Matter components mass is also found.
Feature-Level Fusion of Finger Vein and Fingerprint Based on a Single Finger Image: The Use of Incompletely Closed Near-Infrared Equipment
Authors: Lv Ge-Liang , Shen Lei , Yao Yu-Dong , Wang Hua-Xia , Zhao Guo-Dong
Published: May 2020

Due to its portability, convenience, and low cost, incompletely closed near-infrared (ICNIR) imaging equipment (mixed light reflection imaging) is used for ultra thin sensor modules and have good application prospects. However, equipment with incompletely closed structure also brings some problems. Some finger vein images are not clear and there are sparse or even missing veins, which results in poor recognition performance. For these poor quality ICNIR images, however, there is additional fingerprint information in the image. The analysis of ICNIR images reveals that the fingerprint and finger vein in a single ICNIR image can be enhanced and separated. We propose a feature-level fusion recognition algorithm using a single ICNIR finger image. Firstly, we propose contrast limited adaptive histogram equalization (CLAHE) and grayscale normalization to enhance fingerprint and finger vein texture, respectively. Then we propose an adaptive radius local binary pattern (ADLBP) feature combined with uniform pattern to extract the features of fingerprint and finger vein. It solves the problem that traditional local binary pattern (LBP) is unable to describe the texture features of different sizes in ICNIR images. Finally, we fuse the feature vectors of ADLBP block histogram for a fingerprint and finger vein, and realize feature-layer fusion recognition by a threshold decision support vector machine (T-SVM). The experimentation results showed that the performance of the proposed algorithm was noticeably better than that of the single model recognition algorithm.
Solving the Nonlinear Boundary Layer Flow Equations with Pressure Gradient and Radiation
Authors: Xenos Michalis A. , Petropoulou Eugenia N. , Siokis Anastasios , Mahabaleshwar U. S.
Published: May 2020

The physical problem under consideration is the boundary layer problem of an incompressible, laminar flow, taking place over a flat plate in the presence of a pressure gradient and radiation. For the mathematical formulation of the problem, the partial differential equations of continuity, energy, and momentum are taken into consideration with the boundary layer simplifications. Using the dimensionless Falkner–Skan transformation, a nonlinear, nonhomogeneous, coupled system of partial differential equations (PDEs) is obtained, which is solved via the homotopy analysis method. The obtained analytical solution describes radiation and pressure gradient effects on the boundary layer flow. These analytical results reveal that the adverse or favorable pressure gradient influences the dimensionless velocity and the dimensionless temperature of the boundary layer. An adverse pressure gradient causes significant changes on the dimensionless wall shear parameter and the dimensionless wall heat-transfer parameter. Thermal radiation influences the thermal boundary layer. The analytical results are in very good agreement with the corresponding numerical ones obtained using a modification of the Keller’s-box method.
Parameter Adjustment Strategy and Experimental Development of Hydraulic System for Wave Energy Power Generation
Authors: Zhang Wei
Published: May 2020

This paper develops the dynamic response of a hydrolic-transmission system of wave-power devices under random wave conditions. Through theoretical calculation and experiment analysis, the mathematical model of the hydrolic-transmission system was built to make clear which parameters are related to electric-energy output. The working characteristics of the main parameters are developed through the designed experimental platform. The charging pressure of the accumulator, which affects the rigidity of the hydrolic-transmission system, is analyzed. The throttle valve opening and symmetrical electric loads, which affect the stability and efficiency of the electric energy output, are analyzed. Thus, the energy output curve under different parameter regulations is drawn. Through the orthogonal experimental method, the law curve is further modified, the design principle of hydraulic system parameters under the sea level condition is established, and the optimal design scheme and regulation strategy to the hydraulic conversion system of the power generation device is obtained, to solve the problem that the multiparameter coupling cannot be adjusted quickly and effectively. The energy regulation response mechanism of the hydrolic-transmission system in the wave energy power-generation system is proved.
Time-Varying Delayed H∞ Control Problem for Nonlinear Systems: A Finite Time Study Using Quadratic Convex Approach
Authors: Emharuethai Chanikan , Niamsup Piyapong , Ramachandran Raja , Weera Wajaree
Published: May 2020

In this manuscript, we consider the finite-time H ∞ control for nonlinear systems with time-varying delay. With the assistance of a novel Lyapunov-Krasovskii functional which includes some integral terms, a matrix-based on quadratic convex approach, combined with Wirtinger inequalities and some useful integral inequalities, a sufficient condition of finite-time boundedness is established. A novel feature presents in this paper is that the restriction which is necessary for the upper bound derivative is not restricted to less than 1. Further a H ∞ controller is designed via memoryless state feedback control and a new sufficient conditions for the existence of finite-time H ∞ state feedback for the system are given in terms of linear matrix inequalities (LMIs). At the end, some numerical examples with simulations are given to illustrate the effectiveness of the obtained result.
Nonlocal Mechanical Behavior of Layered Nanobeams
Authors: Barretta Raffaele , Čanađija Marko , Marotti de Sciarra Francesco
Published: May 2020

The research at hand deals with the mechanical behavior of beam-like nanostructures. Nanobeams are assembled of multiple layers of different materials and geometry giving a layered nanobeam. To properly address experimentally noticed size effects in structures of this type, an adequate nonlocal elasticity formulation must be applied. The present model relies on the stress-driven integral methodology that effectively circumvents known deficiencies of other approaches. As a main contribution, a set of differential equations and boundary conditions governing the underlaying mechanics is proposed and applied to two benchmark examples. The obtained results show the expected stiffening nonlocal behavior exhibiting most of smaller and smaller structures and modern devices.
HMCTS-OP: Hierarchical MCTS Based Online Planning in the Asymmetric Adversarial Environment
Authors: Lu Lina , Zhang Wanpeng , Gu Xueqiang , Ji Xiang , Chen Jing
Published: May 2020

The Monte Carlo Tree Search (MCTS) has demonstrated excellent performance in solving many planning problems. However, the state space and the branching factors are huge, and the planning horizon is long in many practical applications, especially in the adversarial environment. It is computationally expensive to cover a sufficient number of rewarded states that are far away from the root in the flat non-hierarchical MCTS. Therefore, the flat non-hierarchical MCTS is inefficient for dealing with planning problems with a long planning horizon, huge state space, and branching factors. In this work, we propose a novel hierarchical MCTS-based online planning method named the HMCTS-OP to tackle this issue. The HMCTS-OP integrates the MAXQ-based task hierarchies and the hierarchical MCTS algorithms into the online planning framework. Specifically, the MAXQ-based task hierarchies reduce the search space and guide the search process. Therefore, the computational complexity is significantly reduced. Moreover, the reduction in the computational complexity enables the MCTS to perform a deeper search to find better action in a limited time. We evaluate the performance of the HMCTS-OP in the domain of online planning in the asymmetric adversarial environment. The experiment results show that the HMCTS-OP outperforms other online planning methods in this domain.
The Effect of Prolonged Running on the Symmetry of Biomechanical Variables of the Lower Limb Joints
Authors: Gao Zixiang , Mei Qichang , Fekete Gusztáv , Baker Julien S , Gu Yaodong
Published: May 2020

The aim of this study was to examine whether there are kinematic and kinetic differences in the lower limb and whether the symmetry of the lower extremities is different after prolonged-running. Fifteen healthy male amateur runners (age: 22 ± 1 years, height: 173 ± 8 cm, mass: 65 ± 7 kg, BMI: 21.62 ± 2 kg/m2) were recruited as participants for this study. A Vicon eight-camera motion capture system and Kistler force plate were used to collect kinematic and kinetic parameters. A motorized treadmill, 15-point Borg scale and heart rate bands were used to monitor fatigue during a running-induced fatigue protocol. Paired sample T tests were used to check statistical difference (p = 0.05) between the lower limbs and the symmetry changes in pre-fatigue and post-fatigue running sessions. The symmetry angle (SA) of the knee flexion angle, hip flexion angle and hip extension angle in post-fatigue was significantly greater than in pre-fatigue, increasing by 4.32%, 10.71%, and 23.12%, respectively. Moreover, the SA of hip flexion moment increased by 2.61%. However, the knee extension velocity and hip flexion velocity became more symmetrical than in pre-fatigue (p < 0.05), the SA decreased by 5.91% and 5.45%, respectively. Differences in limb function during post-fatigue may lead to changes of symmetry in the lower limbs. The variables of asymmetry may be used as a compensation mechanism to maintain gait stability. Physical therapy assessment of fatigue injuries and long-distance running training programs may want to consider the changes in symmetry due to limb dominance.
On (ψ, ϕ)-Rational Contractions
Authors: Fulga Andreea
Published: May 2020

In this paper, we examine the notion of ( ψ , ϕ )-contractions by involving rational forms in the context of complete metric spaces. We note that some well-known fixed point theorems for rational forms can be deduced from our main results. We also consider some examples to indicate the validity of the presented results.
A Vector Field Texture Generation Method without Convolution Calculation
Authors: Du Xiaofu , Liu Huilin , Tseng Hsien-Wei , Meen Teen-Hang
Published: May 2020

In the LIC algorithm process, symmetrical streamline tracing is used to symmetrically convolve the original values of all the primitive values that pass by to obtain the resulting texture. In this process, streamline tracking and convolution consume a lot of computing resources. To generate more expressive textures for vector fields with less time consumption, a novel method named random increment streamline (RIS) is put forward, which can generate streamline textures without convolution calculations. First, the mesh unit filling preprocessing (MUFP) method is presented to transform an undressed irregular grid into a special kind of regular grid named a “texture pixel”, and the point location and interpolation processes of all sampling points in the texture pixels are calculated before streamline tracking. Second, the random increment streamline method is used to generate line integral convolution style textures without any convolution calculations, thus greatly reducing the algorithm’s time consumption. Third, the vector directions at each point in the static vector field are clearly expressed using the periodic cyclic animation method. Finally, several simplifications of the RIS algorithm are discussed, which help to achieve a better visual effect with faster speed. The programming results show that the method is faster and more applicable than the traditional LIC method and provides clearer expression of the vector field.
Pyrroloindole-Based Dynamic Combinatorial Chemistry
Authors: Gianga Tiberiu-Marius , Răsădean Dora-Maria , Pantoș G. Dan
Published: May 2020

We report a new class of building blocks for Dynamic Combinatorial Chemistry (DCC) based on the pyrroloindole scaffold. The attachment of l-cysteine on the α, α′ positions of the core makes the molecule suitable for disulfide exchange in aqueous dynamic combinatorial libraries (DCLs). The synthesis of the core follows a modified version of the Knoevenagel–Hemetsberger approach. The new building block (l-PI) is fluorescent (Φ = 48%) and relatively stable towards thermal and photodegradation. The chirality of the cysteine is transferred to the electron-rich pyrroloindole core. Homo- and heterochiral DCLs of l-PI with electron-deficient l- and d-naphthalenediimide (NDI) lead to similar library distributions regardless of the enantiomer used. When no salt is present, the major component is a dimer, while dimers and tetramers are obtained at increased ionic strength.
Enhancing the Robustness of Dynamical Decoupling Sequences with Correlated Random Phases
Authors: Wang Zhenyu , Casanova Jorge , Plenio Martin B.
Published: May 2020

We show that the addition of correlated phases to the recently developed method of randomized dynamical decoupling pulse sequences can improve its performance in quantum sensing. In particular, by correlating the relative phases of basic pulse units in dynamical decoupling sequences, we are able to improve the suppression of the signal distortion due to π pulse imperfections and spurious responses due to finite-width π pulses. This enhances the selectivity of quantum sensors such as those based on NV centers in diamond.
Statistical Inference for the Inverted Scale Family under General Progressive Type-II Censoring
Authors: Gao Jing , Bai Kehan , Gui Wenhao
Published: May 2020

Two estimation problems are studied based on the general progressively censored samples, and the distributions from the inverted scale family (ISF) are considered as prospective life distributions. One is the exact interval estimation for the unknown parameter θ , which is achieved by constructing the pivotal quantity. Through Monte Carlo simulations, the average 90 % and 95 % confidence intervals are obtained, and the validity of the above interval estimation is illustrated with a numerical example. The other is the estimation of R = P ( Y < X ) in the case of ISF. The maximum likelihood estimator (MLE) as well as approximate maximum likelihood estimator (AMLE) is obtained, together with the corresponding R-symmetric asymptotic confidence intervals. With Bootstrap methods, we also propose two R-asymmetric confidence intervals, which have a good performance for small samples. Furthermore, assuming the scale parameters follow independent gamma priors, the Bayesian estimator as well as the HPD credible interval of R is thus acquired. Finally, we make an evaluation on the effectiveness of the proposed estimations through Monte Carlo simulations and provide an illustrative example of two real datasets.
A Phenotypic and Genotypic Evaluation of Developmental Toxicity of Polyhexamethylene Guanidine Phosphate Using Zebrafish Embryo/Larvae
Authors: Song Jeongah , Eghan Kojo , Lee Sangwoo , Park Jong-Su , Yoon Seokjoo , Pimtong Wittaya , Kim Woo-Keun
Published: May 2020

Polyhexamethylene guanidine-phosphate (PHMG-P), a guanidine-based cationic antimicrobial polymer, is an effective antimicrobial biocide, potent even at low concentrations. Due to its resilient bactericidal properties, it has been used extensively in consumer products. It was safely used until its use in humidifiers led to a catastrophic event in South Korea. Epidemiological studies have linked the use of PHMG-P as a humidifier disinfectant to pulmonary fibrosis. However, little is known about its harmful impacts other than pulmonary fibrosis. Thus, we applied a zebrafish embryo/larvae model to evaluate developmental and cardiotoxic effects and transcriptome changes using RNA-sequencing. Zebrafish embryos were exposed to 0.1, 0.2, 0.3, 0.4, 0.5, 1, and 2 mg/L of PHMG-P from 3 h to 96 h post fertilization. 2 mg/L of PHMG-P resulted in total mortality and an LC50 value at 96 h was determined at 1.18 mg/L. Significant developmental changes were not observed but the heart rate of zebrafish larvae was significantly altered. In transcriptome analysis, immune and inflammatory responses were significantly affected similarly to those in epidemiological studies. Our qPCR analysis (Itgb1b, TNC, Arg1, Arg2, IL-1β, Serpine-1, and Ptgs2b) also confirmed this following a 96 h exposure to 0.4 mg/L of PHMG-P. Based on our results, PHMG-P might induce lethal and cardiotoxic effects in zebrafish, and crucial transcriptome changes were linked to immune and inflammatory response.
Clostridium perfringens Epsilon-Toxin Impairs the Barrier Function in MDCK Cell Monolayers in a Ca2+-Dependent Manner
Authors: Nagahama Masahiro , Seike Soshi , Ochi Sadayuki , Kobayashi Keiko , Takehara Masaya
Published: May 2020

Epsilon-toxin produced by Clostridium perfringens significantly contributes to the pathogeneses of enterotoxemia in ruminants and multiple sclerosis in humans. Epsilon-toxin forms a heptameric oligomer in the host cell membrane, promoting cell disruption. Here, we investigate the effect of epsilon-toxin on epithelial barrier functions. Epsilon-toxin impairs the barrier integrity of Madin-Darby Canine Kidney (MDCK) cells, as demonstrated by decreased transepithelial electrical resistance (TEER), increased paracellular flux marker permeability, and the decreased cellular localization of junctional proteins, such as occludin, ZO-1, and claudin-1. U73122, an endogenous phospholipase C (PLC) inhibitor, inhibited the decrease in TEER and the increase in the permeability of flux marker induced by epsilon-toxin. The application of epsilon-toxin to MDCK cells resulted in the biphasic formation of 1,2-diacylglycerol (DAG) and inositol-1,4,5-triphosphate (IP3). U73122 blocked the formation of DAG and IP3 induced by the toxin. Epsilon-toxin also specifically activated endogenous PLC-γ1. Epsilon-toxin dose-dependently increased the cytosolic calcium ion concentration ([Ca2+]i). The toxin-induced elevation of [Ca2+]i was inhibited by U73122. Cofilin is a key regulator of actin cytoskeleton turnover and tight-junction (TJ) permeability regulation. Epsilon-toxin caused cofilin dephosphorylation. These results demonstrate that epsilon-toxin induces Ca2+ influx through activating the phosphorylation of PLC-γ1 and then causes TJ opening accompanied by cofilin dephosphorylation.
AFB1 Induced Transcriptional Regulation Related to Apoptosis and Lipid Metabolism in Liver of Chicken
Authors: Liu Xueqin , Kumar Mishra Shailendra , Wang Tao , Xu Zhongxian , Zhao Xiaoling , Wang Yan , Yin Huadong , Fan Xiaolan , Zeng Bo , Yang Mingyao , Yang Deying , Ni Qingyong , Li Yan , Zhang Mingwang , Zhu Qing , Chen Feng , Li Diyan
Published: May 2020

Aflatoxin B1 (AFB1) leads to a major risk to poultry and its residues in meat products can also pose serious threat to human health. In this study, after feeding 165-day-old Roman laying hens for 35 days, the toxic effects of aflatoxin B1 at different concentrations were evaluated. The purpose of this study was to explore the mechanism of liver toxicosis responses to AFB1. We found that highly toxic group exposure resulted in liver fat deposition, increased interstitial space, and hepatocyte apoptosis in laying hens. Furthermore, a total of 164 differentially expressed lnRNAs and 186 differentially expressed genes were found to be highly correlated (Pearson Correlation Coefficient > 0.80, p-value < 0.05) by sequencing the transcriptome of control (CB) and highly toxic group (TB3) chickens. We also identify 29 differentially expressed genes and 19 miRNAs that have targeted regulatory relationships. Based on the liver cell apoptosis and fatty liver syndrome that this research focused on, we found that the highly toxic AFB1 led to dysregulation of the expression of PPARG and BCL6. They are cis-regulated by TU10057 and TU45776, respectively. PPARG was the target gene of gga-miR-301a-3p, gga-miR-301b-3p, and BCL6 was the target gene of gga-miR-190a-3p. In summary, highly toxic AFB1 affects the expression levels of protein-coding genes and miRNAs in the liver of Roman layer hens, as well as the expression level of long non-coding RNA in the liver, which upregulates the expression of PPARG and downregulates the expression of Bcl-6. Our study provides information on possible genetic regulatory networks in AFB1-induced hepatic fat deposition and hepatocyte apoptosis.
Health-Related Quality of Life Outcomes from Botulinum Toxin Treatment in Spasticity
Authors: Roncoroni Lorenzo Pietro , Weiss Daniel , Hieber Leonhard , Sturm Justine , Börtlein Axel , Mayr Ingo , Appy Matthias , Kühnler Benedicta , Buchthal Joachim , Dippon Christian , Arnold Guy , Wächter Tobias
Published: May 2020

Objective: The effects of botulinum toxin injections (BoNT) on health-related quality of life along the complex spectrum of spasticity needs further characterization to guide practitioners in a real-life therapeutic environment. Methods: In this study, we analyzed 50 consecutive and unselected patients with spasticity before and four weeks after re-injection of botulinum toxin. Health-related quality of life in terms of the EuroQol (EQ) as well as further motor and non-motor characteristics were assessed. Results: BoNT improved the EQ visual analog scale (EQ VAS). In addition, state of health and pain maxima improved. The EQ VAS improvement correlated with pre-injection characteristics of the EQ VAS and life satisfaction in the “movement disorders” domain. Conclusion: EQ VAS is sensitive for monitoring HR-QoL outcomes in an unselected real life observational cohort. This study may inform future studies intended to validate prediction variables that could inform on HR-QoL effects of BoNT treatment in spasticity.
In Vitro Toxicokinetics and Phase I Biotransformation of the Mycotoxin Penitrem A in Dogs
Authors: Uhlig Silvio , Ivanova Lada , Voorspoels Pauline , Fæste Christiane Kruse
Published: May 2020

The tremorgenic mycotoxin penitrem A is produced by Penicillium species as a secondary metabolite on moldy food and feed. Dogs are sometimes exposed to penitrem A by consumption of spoiled food waste or fallen fruit. The lipophilic toxin crosses the blood-brain barrier and targets neuroreceptors and neurotransmitter release mechanisms in the central and peripheral nervous systems. Typical symptoms of penitrem A intoxication are periodical or continuous tremors, which can be passing, persistent or lethal, depending on the absorbed dose. There is presently no information on the biotransformation and toxicokinetics of penitrem A in dogs. The aim of the present study was therefore to identify potential metabolites of the toxin by performing in vitro biotransformation assays in dog liver microsomes. Analyses by liquid chromatography coupled to high-resolution mass spectrometry led to the provisional identification of eleven penitrem A phase I metabolites, which were tentatively characterized as various oxidation products. Furthermore, elimination parameters determined in in vitro assays run under linear kinetics were used for in vitro-to-in vivo extrapolation of the toxicokinetic data, predicting a maximal bioavailability of more than 50%. The metabolite profile detected in the in vitro assays was similar to that observed in the plasma of an intoxicated dog, confirming the predictive capability of the in vitro approach.
Rethinking Stormwater: Analysis Using the Hydrosocial Cycle
Authors: Wilfong Matthew , Pavao-Zuckerman Mitchell
Published: May 2020

Water management and governance continues to rely on the scientific and engineering principles of the hydrologic cycle for decision-making on policies and infrastructure choices. This over-reliance on hydrologic-based, technocratic, command-and-control management and governance tends to discount and overlook the political, social, cultural, and economic factors that shape water-society relationships. This paper utilizes an alternative framework, the hydrosocial cycle, to analyze how water and society shape each other over time. In this paper, the hydrosocial framework is applied to stormwater management in the United States. Two hydrosocial case studies centered on rain and stormwater are investigated to highlight how stormwater management can benefit from a hydrosocial approach. The insights and implications from these case studies are then applied to stormwater management by formulating key questions that arise under the hydrosocial framework. These key questions are significant to progressing stormwater management to more sustainable, resilient, and equitable outcomes for environmental and public safety and health. This paper frames a conversation for incorporating the hydrosocial framework into stormwater management and demonstrates the need for an interdisciplinary approach to water management and governance issues.
Consistent Boundary Conditions for Age Calculations
Authors: Deleersnijder Eric , Draoui Insaf , Lambrechts Jonathan , Legat Vincent , Mouchet Anne
Published: May 2020

Age can be evaluated at any time and position to understand transport processes taking place in the aquatic environment, including for reactive tracers. In the framework of the Constituent-oriented Age and Residence time Theory (CART), the age of a constituent or an aggregate of constituents, including the water itself, is usually defined as the time elapsed since leaving the boundary where the age is set or reset to zero. The age is evaluated as the ratio of the age concentration to the concentration, which are the solution of partial differential equations. The boundary conditions for the concentration and age concentration cannot be prescribed independently of each other. Instead, they must be derived from boundary conditions designed beforehand for the age distribution function (the histogram of the ages, the age theory core variable), even when this variable is not calculated explicitly. Consistent boundary conditions are established for insulating, departure and arrival boundaries. Gas exchanges through the water–air interface are also considered. Age fields ensuing from consistent boundary conditions and, occasionally, non-consistent ones are discussed, suggesting that the methodology advocated herein can be utilized by most age calculations, be they used for diagnosing the results of idealised models or realistic ones.
Impact of Nanoscale Magnetite and Zero Valent Iron on the Batch-Wise Anaerobic Co-Digestion of Food Waste and Waste-Activated Sludge
Authors: Kassab Ghada , Khater Dima , Odeh Fadwa , Shatanawi Khaldoun , Halalsheh Maha , Arafah Mazen , van Lier Jules B.
Published: May 2020

As a potential approach for enhanced energy generation from anaerobic digestion, iron-based conductive nanoparticles have been proposed to enhance the methane production yield and rate. In this study, the impact of two different types of iron nanoparticles, namely the nano-zero-valent-iron particles (NZVIs) and magnetite (Fe3O4) nanoparticles (NPs) was investigated, using batch test under mesophilic conditions (35 °C). Magnetite NPs have been applied in doses of 25, 50 and 80 mg/L, corresponding to 13.1, 26.2 and 41.9 mg magnetite NPs/gTS of substrate, respectively. The results reveal that supplementing anaerobic batches with magnetite NPs at a dose of 25 mg/L induces an insignificant effect on hydrolysis and methane production. However, incubation with 50 and 80 mg/L magnetite NPs have instigated comparable positive impact with hydrolysis percentages reaching approximately 95% compared to 63% attained in control batches, in addition to a 50% enhancement in methane production yield. A biodegradability percentage of 94% was achieved with magnetite NP doses of 50 and 80 mg/L, compared to only 62.7% obtained with control incubation. NZVIs were applied in doses of 20, 40 and 60 mg/L, corresponding to 10.8, 21.5 and 32.2 mg NZVIs/gTS of substrate, respectively. The results have shown that supplementing anaerobic batches with NZVIs revealed insignificant impact, most probably due to the agglomeration of NZVI particles and consequently the reduction in available surface area, making the applied doses insufficient for measurable effect.
An Experimental Setup to Investigate Non-Newtonian Fluid Flow in Variable Aperture Channels
Authors: Lenci Alessandro , Chiapponi Luca
Published: May 2020

Non-Newtonian fluid flow in porous and fractured media is of considerable technical and environmental interest. Here, the flow of a non-Newtonian fluid in a variable aperture fracture is studied theoretically, experimentally and numerically. We consider a shear-thinning power-law fluid with flow behavior index n. The natural logarithm of the fracture aperture is a two-dimensional, spatially homogeneous and correlated Gaussian random field. An experimental device has been conceived and realized to allow the validation of the theory, and several tests are conducted with Newtonian and shear-thinning fluids and different combinations of parameters to validate the model. For Newtonian fluids, experimental results match quite well the theoretical predictions, mostly with a slight overestimation. For non-Newtonian fluids, the discrepancy between experiments and theory is larger, with an underestimation of the experimental flow rate. We bear in mind the high shear-rates involved in the experiments, covering a large range where simple models seldom are effective in reproducing the process, and possible interferences like slip at the wall. For all test conditions, the comparison between analytical and numerical model is fairly good.
The Impact of Permafrost Degradation on Lake Changes in the Endorheic Basin on the Qinghai–Tibet Plateau
Authors: Liu Wenhui , Xie Changwei , Wang Wu , Yang Guiqian , Zhang Yuxin , Wu Tonghua , Liu Guangyue , Pang Qiangqiang , Zou Defu , Liu Hairui
Published: May 2020

Lakes on the Qinghai–Tibetan Plateau (QTP) have experienced significant changes, especially the prevailing lake expansion since 2000 in the endorheic basin. The influence of permafrost thawing on lake expansion is significant but rarely considered in previous studies. In this study, based on Landsat images and permafrost field data, the spatial-temporal area changes of lakes of more than 5 km2 in the endorheic basin on the QTP during 2000–2017 is examined and the impact of permafrost degradation on lake expansion is discussed. The main results are that permafrost characteristics and its degradation trend have close relationships with lake changes. Lake expansion in the endorheic basin showed a southwest–northeast transition from shrinking to stable to rapidly expanding, which corresponded well with the permafrost distribution from island-discontinuous to seasonally frozen ground to continuous permafrost. A dramatic lake expansion in continuous permafrost showed significant spatial differences; lakes expanded significantly in northern and eastern continuous permafrost with a higher ground ice content but slightly in southern continuous permafrost with a lower ground ice content. This spatial pattern was mainly attributed to the melting of ground ice in shallow permafrost associated with accelerating permafrost degradation. Whereas, some lakes in the southern zones of island-discontinuous permafrost were shrinking, which was mainly because the extended taliks arising from the intensified permafrost degradation have facilitated surface water and suprapermafrost groundwater discharge to subpermafrost groundwater and thereby drained the lakes. Based on observation and simulated data, the melting of ground ice at shallow depths below the permafrost table accounted for 21.2% of the increase in lake volume from 2000 to 2016.
Evaluation of Satellite-Derived Soil Moisture in Qinghai Province Based on Triple Collocation
Authors: Zhu Hongchun , Zhang Zhilin , Lv Aifeng
Published: May 2020

Evaluating the reliability of satellite-based and reanalysis soil moisture products is very important in soil moisture research. The traditional methods of evaluating soil moisture products rely on the verification of satellite inversion data and ground observation; however, the ground measurement data is often difficult to obtain. The triple collocation (TC) method can be used to evaluate the accuracy of a product without obtaining the ground measurement data. This study focused on the whole of Qinghai Province, China (31°–40° N, 89°–103° E), and used the TC method to obtain the error variance for satellite-based soil moisture data, the signal-to-noise ratio (SNR) of the same data, and the correlation between the same data and the ground-truth soil moisture, using passive satellite products: Soil Moisture Active Passive (SMAP), Soil Moisture Ocean Salinity (SMOS), Fengyun-3B Microwave Radiation Imager (FY3B), Fengyun-3C Microwave Radiation Imager (FY3C), and Advanced Microwave Scanning Radiometer 2 (AMSR2); an active satellite product Advanced Scatterometer (ASCAT), and reanalysis data Goddard Earth Observing System Model version 5 (GEOS-5) land modeling system. The TC results for the passive satellite data were then compared with the satellite-derived enhanced vegetation index (EVI) to explore the influence of vegetation coverage on the results. The following conclusions are drawn: (1) for the SMAP, SMOS, FY3B, FY3C, and AMSR2 satellite data, the spatial distributions of the TC-derived error variance, the SNR of the satellite-derived soil moisture, and the correlation coefficient between the satellite-derived and ground-truth soil moisture, were all relatively similar, which indirectly verified the reliability of the TC method; and (2) SMOS data have poor applicability for the estimation of soil moisture in Qinghai Province due to their insufficient detection capability in the Qaidam area, high error variance (median 0.0053), high SNR (median 0.43), and low correlation coefficient with ground-truth soil moisture (median 0.57).
Dynamic Changes of Soil Erosion in the Taohe River Basin Using the RUSLE Model and Google Earth Engine
Authors: Wang Hao , Zhao Hu
Published: May 2020

The Taohe River Basin is the largest tributary and an important water conservation area in the upper reaches of the Yellow River. In order to investigate the status of soil erosion in this region, we conducted a research of soil erosion. In our study, several parameters of the revised universal soil loss equation (RUSLE) model are extracted by using Google Earth Engine. The soil erosion modulus of the Taohe River Basin was calculated based on multi-source data, and the spatio-temporal variation characteristics of the soil erosion intensity were analyzed. The results showed the following: (1) the average soil erosion modulus of the Taohe River Basin in 2000, 2005, 2010, 2015 and 2018 were 1424, 1195, 1129, 1099 and 1124 t·ha−1·year−1, respectively, and the overall downward trend was obvious. (2) The ranges of soil erosion in the Taohe River Basin in 2000, 2005, 2010, 2015 and 2018 are basically the same—mainly with slight erosion—and the soil erosion in the middle and lower reaches was more serious. (3) When dealing with the vegetation cover factor and conservation practice factor in the RUSLE model, Google Earth Engine provided a new approach for soil erosion investigation and monitoring over a large area.
Effects of Distinct Revegetation Methods on Growth and Microbial Properties of Vallisneria natans
Authors: Wang Ning , Li Qi , Jiang Mengqi , Zhang Weizhen , Zhang Hao , Song Qixuan , Hu Zhongda , Zhang Jibiao , Zheng Zheng
Published: May 2020

This study investigated the effects of the mud-sinking (MS) method, agar gel-sinking (AS) method and agar gel-sinking with artificial aquatic mat (ASA) method on the growth, physiological characteristics, water purification capacity, and associated microbial community of the different organs of Vallisneria natans (V. natans). Results showed that the growth of agar-based growth (group AS and ASA) were more effective than the mud-wrapped method (group MS), exhibiting longer length, higher fresh weight and biomass of agar-based V. natans with the artificial aquatic mat (group ASA) being higher than those of other groups. MS caused a stress response in the oxidative system, which then inhibited photosynthesis. Results of water quality measurements showed that the three planting methods positively affected water purification without significant differences (p > 0.05). Besides, there was no significant difference (p > 0.05) between the microbial communities in terms of the roots and those found in rhizosphere soils in the MS group with high throughput sequencing. Meanwhile, the addition of agar in the AS and ASA groups increased the diversity of rhizosphere soil microbial communities and reduced the diversity of root microbial communities. Microbial community compositions in the rhizosphere soil and root differed significantly (p < 0.05). High throughput sequencing and scanning electron microscopy (SEM) also revealed that the biofilm on the surfaces were different, with Proteobacteria and Cyanophyta consistently dominating. This study provides new insights on the more effective revegetation methods of V. natans, researched the environmental impact of the addition of agar, and provides some theoretical support for the revegetation of submerged macrophytes under ecological restoration.
Condition for the Incipient Motion of Non-Cohesive Particles Due to Laminar Flows of Power-Law Fluids in Closed Conduits
Authors: Tamburrino Aldo , Traslaviña Cristóbal
Published: May 2020

The results of an experimental study on the condition of incipient transport of non-cohesive particles due to the flow of a power-law fluid in a rectangular pipe are presented in this article. The pipe can change its inclination, and experiments were carried out with positive and negative slopes. From a dimensional analysis, the parameters that define the condition of incipient motion were found and validated with experimental data. Thus, the threshold condition is well defined by a particle Reynolds number and a Galileo number, properly modified to take into account the power-law rheology of the fluid. The experimental data are also presented in a standard Shields diagram, including the data obtained in other studies carried out in open-channel laminar flows of Newtonian and power-law fluids.
Complex Networks Theory for Evaluating Scaling Laws and WDS Vulnerability for Potential Contamination Events
Authors: Nicolini Matteo
Published: May 2020

In the last few years, water utilities have recognized the importance of evaluating the safety of water distribution networks from the potential risks of contamination, arising from failures or from intentional (targeted) or random attacks. Research literature has been recently focused on the optimal design of efficient detection systems, generally expressed as the problem of the optimal placement of monitoring sensors. In this paper, we introduce a methodology for calculating an index of vulnerability that represents the tendency of an injected contaminant to spread over the network. Epanet quality simulations are performed in order to determine the distribution function of the number of potentially contaminated nodes. The results show how such distribution is overall fitted by a stretched exponential law. The comparison with an auto-similar, tree-like network (described by a power-law) allows the determination of the Vulnerability Index, which quantifies how “far” the behavior of a given system deviates from pure scale-freeness. It is analytically calculated by a two-fold approximation of the stretched exponential and provides an alternative way of evaluating robustness against random water contamination. Different networks can then be directly compared, in order to assess and prioritize control measures and interventions.
Meteorological Variability and Groundwater Quality: Examples in Different Hydrogeological Settings
Authors: Lasagna Manuela , Ducci Daniela , Sellerino Mariangela , Mancini Susanna , De Luca Domenico Antonio
Published: May 2020

Rainfall and temperature variability causes changes in groundwater recharge that can also influence groundwater quality by different processes. The aim of this study is the analysis of the hydrogeochemical variations over time due to meteorological variability in two different study areas in Italy: an alluvial aquifer in the Piedmont Po plain and an alluvial-pyroclastic aquifer in the Campanian plain. The examined plains show groundwater with natural quality not satisfying the European drinking water standards, or anthropogenic contamination. The peculiar natural quality is due, in the Campanian plain, to the closeness of volcanic areas, and to the presence of reducing conditions. In Piedmont plain a test site is characterized by a point-source contamination by heavy metals, due to the presence of past industrial activities. In all the examined areas there is a diffuse nitrate contamination. The fluctuations of the ions As, F, Fe, Mn, Cr VI, NO3, and Cl were analyzed and compared, using statistical methods, with the variations over time in precipitation, temperature, and piezometric levels, sometimes significant. Results highlight the importance of the groundwater and meteorological monitoring and the key role of the recharge variation in the hydrogeochemical processes. The linking degree between rainfall/temperature variability and hydrogeochemistry is variable, in function of the typology of chemical species, their origin, and of the aquifer characteristics. The fluctuation of climate variables determines sudden changes in the geochemistry of shallow unconfined aquifers (e.g., in the Piedmont plain), while semiconfined or confined aquifers (e.g., in the Volturno-Regi Lagni plain) react with a greater delay to these variations. Moreover, natural quality is more affected by climatic variations than anthropogenic contamination, which is the result of multiple environmental and anthropic factors.
Diet selection of introduced black ratsRattus rattus L. in relation to plant availability on Berlenga Island, Portugal / Préférence alimentaire des rats noirs introduits Rattus rattus L. en relation avec la disponibilité de la flore sur l’île de Berlenga, Portugal
Authors: Nascimento Tania , Oliveira Nuno , Fagundes Ana Isabel , Tejada-Baena Carlos , Luís Antonio
Published: May 2020

Les rongeurs introduits ont un impact fort sur la faune et la flore locales insulaires. La présence de rats noirs (Rattus rattus) sur l’île de Berlenga peut constituer une menace pour les espèces endémiques et indigènes, en particulier pour la flore. Comprendre la position trophique des rats noirs est essentiel pour engager les efforts de gestion et les actions de conservation des écosystèmes. Dans ce but, nous avons étudié leurs préférences et la sélection de proies par les rats noirs en hiver et au printemps, lorsque les ressources alimentaires sont les plus abondantes. Le régime alimentaire a été étudié en analysant les contenus stomacaux et intestinaux de 23 rats noirs. La détermination de la disponibilité floristique via l’étude de 561 parcelles de 2 × 2 m a également été réalisée. Le régime des rats noirs est principalement composé de plantes (94,1 % / 13 espèces identifiées). Les 5,9 % restants sont composés d’invertébrés de 7 groupes distincts. La totalité des plantes consommées sont indigènes, mais aucune espèce endémique n’a été retrouvée dans les contenus stomacaux. Les graines constituent la majeure partie du bol alimentaire. Cette diète spécifique peut affecter la flore dans son ensemble, à la fois par prédation et dispersion. Des preuves de prédation d’oiseaux ont été trouvées. Des restes de plumes sont présents dans 22 % des estomacs analysés. L’étude montre que les rats noirs ne sont pas totalement des généralistes mais des consommateurs intermédiaires sélectifs et que la grande disponibilité d’une source d’alimentation n’est pas le seul facteur de sélection des proies.