bluuebunny/crossref_metadata_2025 huggingface dataset:
In situ investigation of as grown Cu(In,Ga)Se2 thin films by means of photoemission spectroscopy
Authors: Calvet Wolfram , Ümsür Bünyamin , Steigert Alexander , Prietzel Karsten , Greiner Dieter , Kaufmann Christian A. , Unold Thomas , Lux-Steiner Martha , Lauermann Iver
Published: April 2019

A UHV-transferred Cu(In,Ga)Se2 (CIGSe) thin film prepared by a three-stage process on an Mo-coated float glass was successfully investigated by detailed UPS/XPS and directly compared with air-transferred and cyanide etched samples from the same batch. Besides the fact that the valence band maximum of the UHV-transferred sample is located 1.19 eV below the Fermi level, pointing to a widened bandgap and type inversion, almost no oxygen or sodium was detected on the surface. After air transfer, Na- and O-containing species were found on the CIGSe surface that could be only partially removed upon cyanide etching. The residual and very low Na1s signal is slightly shifted, which is attributed to a modified band bending at the grain boundaries with Ga-, In-, and Se-related oxides still present on the CIGSe surface after the etching process. Thickness analysis reveals that both the sodium containing surface layer (after air-transfer) and the oxygen containing termination layer (after cyanide etching) are restricted to a few monolayers only. Finally, the topmost CIGSe layer appears to be Cu-free due to the fact that no oxidized Cu was found after air exposure. In addition, the Cu core level does not follow the surface termination induced shift of the valence band after the KCN treatment, pinning its maximum 0.77 eV below the Fermi level. These findings are ascribed to a Cu(In,Ga)7Se11 surface as deduced from XPS core level analysis.
RF-plasma MBE growth of epitaxial metallic TaNx transition metal nitride films on SiC
Authors: Katzer D. Scott , Nepal Neeraj , Hardy Matthew T. , Downey Brian P. , Storm David F. , Jin Eric N. , Meyer David J.
Published: April 2019

RF-plasma molecular-beam epitaxy was used to epitaxially grow 3–150-nm-thick metallic TaNx thin films on hexagonal SiC substrates. Single-phase hexagonal γ-Ta2N films were obtained when the starting substrate temperature was ∼900 °C and the active N to Ta ratio was ∼2.5–3. The films were characterized using in situ reflection high-energy electron diffraction and ex situ atomic force microscopy, contactless sheet resistance, x-ray diffraction, and cross-sectional transmission electron microscopy. Smooth, single-crystal, low-resistivity films of epitaxial, hexagonal γ-Ta2N on SiC are demonstrated for films at least ∼50-nm-thick.
Effect of strontium doping on indium zinc oxide thin film transistors fabricated by low-temperature solution process
Authors: Kim Jin-Hyun , Nguyen Manh-Cuong , Nguyen An Hoang-Thuy , Kim Sang-Woo , Choi Su-Jin , Cheon Jong-Gyu , Ji Hyung-Min , Yu Kyoung-Moon , Cho Seong-Yong , Choi Rino
Published: April 2019

Solution-processed metal oxide semiconductors for thin film transistors (TFTs) require high-temperature annealing to improve the electrical performance. On the other hand, a high-temperature process cannot be applied to flexible substrates, which is an obstacle preventing the application of MOS films to flexible devices. This paper reports a simple method for improving the electrical characteristics of low-temperature solution-processed indium zinc oxide (IZO) TFTs with strontium (Sr)-doping and vacuum annealing. The addition of Sr to the IZO thin film decreased the density of oxygen vacancies due to the strong bonding energy of Sr with oxygen ions and improved the electrical stability of the IZO TFTs. On the other hand, vacuum annealing increased the number of oxygen vacancies in the IZO film resulting from the low oxygen partial pressure, which led to an increase in carrier concentration. By combining these two methods, Sr-doped IZO TFTs with a high field-effect mobility of 8.75 cm2 V−1 s−1 at 2 mol. % of Sr doping were fabricated.
Congo Red Fluorescence for Rapid
In Situ
Characterization of Synthetic Curli Systems
Authors: Kan Anton , Birnbaum Daniel P. , Praveschotinunt Pichet , Joshi Neel S.
Published: April 2019

Curli are proteins produced by many bacteria as a structural component of biofilms, and they have recently emerged as a platform for fabrication of biological materials. Curli fibers are very robust and resistant to degradation, and the curli subunits can tolerate many protein fusions, facilitating the biosynthesis of novel functional materials. A serious bottleneck in the development of more sophisticated engineered curli systems is the rapid quantification of curli production by the bacteria. In this work we address this issue by developing a technique to monitor curli production directly in bacterial cultures, allowing for rapid curli quantification in a manner compatible with many powerful high-throughput techniques that can be used to engineer complex biological material systems.
The Structural Basis for a Transition State That Regulates Pore Formation in a Bacterial Toxin
Authors: Wade Kristin R. , Lawrence Sara L. , Farrand Allison J. , Hotze Eileen M. , Kuiper Michael J. , Gorman Michael A. , Christie Michelle P. , Panjikar Santosh , Morton Craig J. , Parker Michael W. , Tweten Rodney K.
Published: April 2019

The cholesterol-dependent cytolysins (CDCs) are the archetype for the superfamily of oligomeric pore-forming proteins that includes the membrane attack complex/perforin (MACPF) family of immune defense proteins and the stonefish venom toxins (SNTX). The CDC/MACPF/SNTX family exhibits a common protein fold, which forms a membrane-spanning β-barrel pore. We show that changing the relative stability of an extensive intramolecular interface within this fold, which is necessarily disrupted to form the large β-barrel pore, dramatically alters the kinetic and temperature-dependent properties of CDC pore formation. These studies show that the CDCs and other members of the CDC/MACPF/SNTX superfamily have the capacity to significantly alter their pore-forming properties to function under widely different environmental conditions encountered by these species.
Chlamydia trachomatis Lipopolysaccharide Evades the Canonical and Noncanonical Inflammatory Pathways To Subvert Innate Immunity
Authors: Yang Chunfu , Briones Michael , Chiou Janice , Lei Lei , Patton Michael John , Ma Li , McClarty Grant , Caldwell Harlan D.
Published: April 2019

Chlamydia trachomatis
is the most common bacterial cause of sexually transmitted infections (STI).
C. trachomatis
STI are commonly asymptomatic, implying a pathogenic strategy for the evasion of innate inflammatory immune responses, a paradox as the
C. trachomatis
outer membrane contains lipopolysaccharide (LPS), a known potent agonist of inflammatory innate immunity. Here, we found that
C. trachomatis
LPS is not capable of engaging the canonical TLR4/MD-2 or noncanonical caspase-11 inflammatory pathways. The inability of
C. trachomatis
LPS to trigger innate immunity inflammatory pathways is related to its unique fatty acid structure. Evolutionary modification of the LPS structure likely evolved as a pathogenic strategy to silence innate host defense mechanisms. The findings might explain the high incidence of asymptomatic chlamydial genital infection.
Comparative Transcriptomic Profiling of Yersinia enterocolitica O:3 and O:8 Reveals Major Expression Differences of Fitness- and Virulence-Relevant Genes Indicating Ecological Separation
Authors: Schmühl Carina , Beckstette Michael , Heroven Ann Kathrin , Bunk Boyke , Spröer Cathrin , McNally Alan , Overmann Jörg , Dersch Petra
Published: April 2019

Yersinia enterocolitica
is a major diarrheal pathogen and is associated with a large range of gut-associated diseases. Members of this species have evolved into different phylogroups with genotypic variations. We performed the first characterization of the
Y. enterocolitica
transcriptional landscape and tracked the consequences of the genomic variations between two different pathogenic phylogroups by comparing their RNA repertoire, promoter usage, and expression profiles under four different virulence-relevant conditions. Our analysis revealed major differences in the transcriptional outputs of the closely related strains, pointing to an ecological separation in which one is more adapted to an environmental lifestyle and the other to a mostly mammal-associated lifestyle. Moreover, a variety of pathoadaptive alterations, including alterations in acid resistance genes, colonization factors, and toxins, were identified which affect virulence and host specificity. This illustrates that comparative transcriptomics is an excellent approach to discover differences in the functional output from closely related genomes affecting niche adaptation and virulence, which cannot be directly inferred from DNA sequences.
Mining Twitter to understand the cardiac rehabilitation barriers and patients’ perceptions
Authors: Krittanawong Chayakrit , Tunhasiriwet Anusith , Zhang HongJu , Aydar Mehmet , Sun Tao , Hassan Virk Hafeez Ul , Herzog Eyal
Published: April 2019

Cardiovascular disease (CVD) is the most common cause of death worldwide. Cardiac rehabilitation (CR) is increasingly recognised as an essential part of clinical care for patients with CVD. CR is a complex intervention that encompasses a multidisciplinary approach that focuses on health education, modification of cardiovascular risk factors, exercise training, physical activity and stress management. In the current American Heart Association/American College of Cardiology guidelines, cardiac rehabilitation is a class IA recommendation for secondary prevention of acute myocardial infarction, percutaneous coronary intervention and cardiac surgery and Class II recommendation for chronic stable heart failure. Despite proven effectiveness, however, participation in traditional CR remains low. Although the reasons for participation and non-participation in CR have been well described, the use of Twitter to explore public perceptions of CR has not yet been formally reported. To the best of our knowledge, the analysis of Twitter for insights on CR is a novel investigation that is relevant for addressing significant problems related to CR awareness in the digital age.

We performed data mining of Twitter to assess patients’ perceptions regarding CR and the reasons for their participation and non-participation in CR between 23 July 2015 and 22 October 2017.

We analysed a total of 5515 Twitter messages. Tweets associated with CR were often used to self-report on health status either before or after participating in CR or contained emotional language with positive or negative comments, advertisements or updated news.

Twitter users wrote mainly positive comments about CR, suggesting the platform has the potential to disseminate both the benefits of CR and its research to the public on the worldwide scale.
Deciphering the complexity of the 4q and 10q subtelomeres by molecular combing in healthy individuals and patients with facioscapulohumeral dystrophy
Authors: Nguyen Karine , Broucqsault Natacha , Chaix Charlene , Roche Stephane , Robin Jérôme D , Vovan Catherine , Gerard Laurene , Mégarbané André , Urtizberea Jon Andoni , Bellance Remi , Barnérias Christine , David Albert , Eymard Bruno , Fradin Melanie , Manel Véronique , Sacconi Sabrina , Tiffreau Vincent , Zagnoli Fabien , Cuisset Jean-Marie , Salort-Campana Emmanuelle , Attarian Shahram , Bernard Rafaëlle , Lévy Nicolas , Magdinier Frederique
Published: April 2019

Background

Subtelomeres are variable regions between telomeres and chromosomal-specific regions. One of the most studied pathologies linked to subtelomeric imbalance is facioscapulohumeral dystrophy (FSHD). In most cases, this disease involves shortening of an array of D4Z4 macrosatellite elements at the 4q35 locus. The disease also segregates with a specific A-type haplotype containing a degenerated polyadenylation signal distal to the last repeat followed by a repetitive array of β-satellite elements. This classification applies to most patients with FSHD. A subset of patients called FSHD2 escapes this definition and carries a mutation in the SMCHD1 gene. We also recently described patients carrying a complex rearrangement consisting of a cis-duplication of the distal 4q35 locus identified by molecular combing.

Methods

Using this high-resolution technology, we further investigated the organisation of the 4q35 region linked to the disease and the 10q26 locus presenting with 98% of homology in controls and patients.

Results

Our analyses reveal a broad variability in size of the different elements composing these loci highlighting the complexity of these subtelomeres and the difficulty for genomic assembly. Out of the 1029 DNA samples analysed in our centre in the last 7 years, we also identified 54 cases clinically diagnosed with FSHD carrying complex genotypes. This includes mosaic patients, patients with deletions of the proximal 4q region and 23 cases with an atypical chromosome 10 pattern, infrequently found in the control population and never reported before.

Conclusion

Overall, this work underlines the complexity of these loci challenging the diagnosis and genetic counselling for this disease.
Evaluation of additional confinement for three-dimensional geoinclusions under general stress state
Authors: Punetha Piyush , Nimbalkar Sanjay , Khabbaz Hadi
Published: April 2019

Three-dimensional cellular geoinclusions (e.g., geocells, scrap tires) offer all-around confinement to the granular infill materials, thus improving their strength and stiffness. The accurate evaluation of extra confinement offered by these geoinclusions is essential for predicting their performance in the field. The existing models to evaluate the additional confinement are based on either a plane-strain or axisymmetric stress state. However, these geoinclusions are more likely to be subjected to the three-dimensional stresses in actual practice. This note proposes a semi-empirical model to evaluate the additional confinement provided by cellular geoinclusions under the three-dimensional stress state. The proposed model is successfully validated against the experimental data. A parametric study is conducted to investigate the influence of input parameters on additional confinement. Results reveal that the simplification of the three-dimensional stress state into axisymmetric or plane-strain condition has resulted in inaccurate and unreliable results. The extra confinement offered by the geoinclusion shows substantial variation along the intermediate and minor principal stress directions depending on the intermediate principal stress, infill soil, and geoinclusion properties. The magnitude of additional confinement increases with an increase in the geoinclusion modulus. The findings are crucial for accurate assessment of the in situ performance of three-dimensional cellular geoinclusions.
Surface fuel loads following a coastal–transitional fire of unprecedented severity: Boulder Creek fire case study
Authors: Peterson Kate F. , Eskelson Bianca N.I. , Monleon Vicente J. , Daniels Lori D.
Published: April 2019

British Columbia experienced three years with notably large and severe wildfires since 2015. Multiple stand-replacing wildfires occurred in coastal–transitional forests, where large fires are typically rare, and thus, information on post-fire carbon is lacking. Because of their carbon storage potential, coastal–transitional forests are important in the global carbon cycle. We examined differences in surface fuel carbon among fire severity classes in 2016, one year after the Boulder Creek fire, which burned 6 735 ha of coastal–transitional forests in 2015. Using remotely sensed indices (dNBR), we partitioned the fire area into unburned (control), low-, moderate-, and high-severity classes. Field plots were randomly located in each class. At each plot, surface fuel carbon was quantified by type, namely coarse, small, and fine woody material, duff, and litter, and carbon mass by fuel type was compared among severity classes. Total surface fuel carbon did not differ significantly between burned and unburned plots; however, there was significantly less duff and litter carbon in burned plots. Remotely sensed severity classes did not properly capture wildfire impacts on surface fuels, especially at lower severities. Pre-fire stand characteristics are also important drivers of surface fuel loads. This case study provides baseline data for examining post-fire fuel carbon dynamics in coastal–transitional British Columbia.
Bott–Chern harmonic forms on complete Hermitian manifolds
Authors: Piovani Riccardo , Tomassini Adriano
Published: April 2019

Let [Formula: see text] be a Hermitian manifold of complex dimension [Formula: see text]. Assume that the torsion of the Chern connection [Formula: see text] is bounded, and that there exists a [Formula: see text]exhausting function [Formula: see text] such that [Formula: see text] are bounded. We characterize [Formula: see text] Bott–Chern harmonic forms, extending the usual result that holds on compact Hermitian manifolds. Finally, if [Formula: see text] is Kähler complete, [Formula: see text], with [Formula: see text] bounded, and the sectional curvature is bounded, then we get a vanishing theorem for [Formula: see text] Bott–Chern harmonic [Formula: see text]-forms, if [Formula: see text].
How to produce an arbitrarily small tensor to scalar ratio
Authors: Brooker D. J.
Published: April 2019

In this paper, construct a toy a model which demonstrates that large field single scalar inflation can produce an arbitrarily small scalar to tensor ratio in the window of e-foldings recoverable from CMB experiments. This is done by generalizing the [Formula: see text]-attractor models to allow the potential to approach a constant as rapidly as we desire for super-Planckian field values. This implies that a non-detection of [Formula: see text] alone can never rule out entirely the theory of large field inflation.
Anomaly of dark matter
Authors: Das Abhishek , Sidharth B. G.
Published: April 2019

Latest observations by Riess and coworkers in 2017 have reconfirmed their earlier observation that the universe is accelerating some 8% faster than the currently accepted cosmological model described. In this paper, we argue that this discrepancy can be eliminated by considering a universe consisting only of matter and dark energy. Interestingly, recently Mark Swissbank, R. Genzel et al. have concluded that nearly en billion years ago dark matter concentration was negligible.
The relation between the composition, structure and absorption properties of ultra-high frequency radio waves of poly(vinylidene fluoride)/magnetite nanocomposites
Authors: Ramazanov M. A. , Hajiyeva F. V. , Shirinova H. A. , Mamedov H. M.
Published: April 2019

In the presented work, nanocomposites based on poly (vinylidene fluoride) (PVDF) and magnetite Fe3O4 nanoparticles were prepared. The structure and content of nanocomposite materials were studied by using scanning electron microscope (SEM), atomic-force microscope (AFM) and X-Ray diffraction (XRD). Magnetic properties of PVDF[Formula: see text]+[Formula: see text]Fe3O4 nanocomposites have been studied upon increasing nanoparticle content in polymer matrix upto 20%, revealing superparamagnetic behavior as Fe3O4 nanoparticles in polymer matrix act out like single-domain particles. It has also been observed that PVDF[Formula: see text]+[Formula: see text]Fe3O4-based nanocomposites can absorb the electromagnetic waves in the high frequency range 0.1–30 GHz. It has been shown that the absorption of high frequency radio waves by PVDF[Formula: see text]+[Formula: see text]Fe3O4 nanocomposites can be explained by the different molecular structures and also by the scattering of the radio waves at the boundary of nanoparticle-polymer matrix.
Structural, electronic, optical and elastic properties of layered rhombohedral compounds ALaSe2(A=K, Rb): Insights from an ab initio study
Authors: Azzouz L. , Halit M. , Allal A. , Maabed S. , Bouchenafa M. , Ahmed R. , Seddik T. , Bouhemadou A. , Khenata R.
Published: April 2019

We report the results of first-principles calculations regarding the structural parameters, elastic moduli, electronic structure and optical properties of the ternary rhombohedral layered compounds, KLaSe2 and RbLaSe2. These calculations were performed by employing the pseudo-potential plane-wave (PP-PW) method. Although the calculated structural parameters (a, c, V, c/a, bond-length d) using different exchange and correlation approximations are found in nice harmony with the available experimental data, the best agreement is obtained with the GGA-PW91 functional. The effect of the K–Rb substitution is noted very clearly on the degree of ionic bonding of the A–Se bond (A[Formula: see text]=[Formula: see text]K, Rb). The electronic band structure and the density of states (DoS) plots reveal the semiconducting characteristics of both compounds with an indirect bandgap energy, E[Formula: see text] of about 2 eV. The mechanical stability of the ALaSe2 compounds is investigated for the first time by calculating the single-crystal elastic constants C[Formula: see text] using the stress-strain approach. In order to understand the linear optical properties of the studied systems, frequency-dependent polarized optical functions were computed for an energy range from 0.0 eV to 18 eV. Our calculated optical spectra reveal the isotropic nature of the optical properties of the ALaSe2 compounds.
Phase shift of solitary wave in a one-dimensional granular chain
Authors: Yang Xian-Qing , Yang Yao , Jiao Yang , Zhang Wei
Published: April 2019

In this paper, both the fifth-order Runge–Kutta numerical scheme and binary collision approximation are used to study the phase shift. Both numerical and theoretical results are shown that the solitary wave after head-on collision propagates along the chain behind the reference wave in both even and odd numbers of grain chains. It is the well-known feature of the appearance of the phase shift. Those results are in agreement with the experimental results. Furthermore, it is found that the phase shift is not only related to the collision position of the waves, but also to the position where the time is measured. The value of phase shift increases nonmonotonously with increasing the velocity of the opposite propagation of the wave. Binary collision approximation is applied to analyze the phase shift, and it is found that theoretical results agree well with numerical results, especially in the case of phase shift in odd chain.
Physical properties of high-temperature solid alkali chlorides by molecular dynamics simulation using a recent EIM interatomic potential
Authors: Cui Xiandai , Zhu Jiaoqun , Xu Hong , Cheng Xiaomin , Zhou Weibing
Published: April 2019

Thermophysical properties of phase change material NaCl and KCl were calculated using molecular dynamics (MD) simulations and a recent EIM interatomic potential. Density, thermal expansion coefficient, specific heat capacity were computed using equilibrium MD (EMD) simulations. The results are very close to the experimental values. The thermal conductivity was computed using two non-equilibrium MD (NEMD) methods and the results were compared with the experimental data. They appear to be relatively reasonable. Binary NaCl/KCl systems have also been investigated. The specific heat capacity with different compositions are calculated. They are very close with recent experimental results.
Room-temperature and flexible PEDOT:PSS–WO3 gas sensor for nitrogen dioxide detection
Authors: Shinde Swapnil , Jiang Chang-Yuan , Zheng Cheng-Xuan , Wang Yi-Zhen , Lin Keh-Moh , Koinkar Pankaj M.
Published: April 2019

In this paper, a resistance type gas sensor which consists of tungsten oxide (PEDOT:PSS), [Formula: see text] particles and silver finger electrodes was prepared on glass as well as (PET) substrates. The structural and surface morphological properties of the sensors were studied using (XRD), UV-visible, (FTIR), (FE-SEM) and 3D optical microscopy. The influence of fabrication parameters on the sensibility for nitrogen dioxide [Formula: see text] detection is discussed. Experimental results reveal that the sensor with [Formula: see text] content of 2 g/mL shows the highest response rate of 2.31 with increasing concentration up to 80 ppm of nitrogen dioxide gas. The response of the flexible gas sensor reveals improved sensing performance after 500 bending tests.
Influence on crack profiles of multi-layered Al/CFRP hybrid composites by using FE simulation
Authors: Yoon Sung-Min , Park Soo-Jeong , Kim Yun-Hae
Published: April 2019

This study aims to investigate a finite element analysis on Al/CFRP Hybrid composites with a flaw in-between bonding surfaces. 2D model was considered to simplify the 4-layered structures with a circular flaw. The determination of debonding condition on multi-layered hybrid composites is subtle because the crack paths are unpredictable. In this model, the crack profiles depend on the applied stress, materials, bonding strengths and initial shapes of the flaw. The main idea is to find the key reason of failure on this material by means of fracture mechanics approach. The crack opening profiles are interesting to determine what kinds of factors are more influential for the structure. Williams expansion was used to analyze the profiles by the simulation results. We finally take into account the results to discuss the main fracture mechanism with the influential factors.
Study on improvement of tensile strength in lap-welding of pure titanium using disk laser
Authors: Kim Ji Sung , Kim Jong-Do
Published: April 2019

Laser welding has the benefit of hardly causing welding deformation as it requires less heat input than existing welding methods. The heat input is determined by the laser output and welding speed, and the penetration depth, bead width, joining length, and bead shape are varied depending on these two welding parameters. In this study, bead and lap welding were performed on a thin pure titanium plate with a thickness of 0.5 mm using a disk laser with a maximum output of 3.3 kW. Weldability was evaluated by observing the penetration depth, bead width, joining length, and bead shape for different laser outputs and welding speeds. Results show that a weld zone with excellent joining length can be obtained for an output of 1.1 kW and speed of 2.5 m/min, as well as for an output of 1.3 kW and speed of 3.5 m/min in lap welding. Tensile-shear test was conducted with the specimens under these two conditions to investigate their mechanical characteristics.
Sensing mechanism analysis on one-dimensional photonic crystal with air slot-porous silicon-air slot F–P cavity
Authors: Chen Ying , Gao Xinbei , Luo Pei , Xu Yangmei , Cao Jinggang , Xie Jinchao
Published: April 2019

Based on the evanescent wave resonance, a photonic crystal sensing structure with air slot-porous silicon-air slot Fabry–Perot cavity (F–P cavity) is proposed. Taking the F–P cavity as the sensing unit, when the gas to be detected is filled into the sensing unit, the refractive index of the air slot will be changed and the refractive index of the porous silicon layer will also be varied, both of which will shift the resonant peak and greatly increase the sensitivity of the sensor. By adjusting the structural parameters, the quality factor (Q value) can be optimized. A model for the relationship between the resonant wavelength and the refractive index of the detected organic gas was established, and the refractive index sensing performance was analyzed. The results show that the Q value of the structure can attain to 12312.2 and the sensitivity is about 8661.708 nm/RIU, which can provide effective theoretical reference and technical guidance for organic gas detection with low concentration.
Interactive decision support system for planned student scheduling using same-time scheduling in timetable
Authors: Guleria Sanjeev K. , Lal Arvind K.
Published: April 2019

Student scheduling takes place after the timetable is prepared. This is a very simple activity. This study is aimed at creating an interactive decision support system for planning related to student scheduling. This planning creates constraints at the pre-timetabling stage so that the complex part of student scheduling is easy at the post-timetabling stage. This study aims to address simultaneous study of backlog courses alongwith regular courses. Two methodologies are suggested to create these constraints which can be used to create different sets of courses scheduled at the same time. These methodologies employ assignment problem iteratively to arrive at courses to be scheduled at the same time. This research work has been tested with the real datasets of four semesters.
Interaction solutions for the (2+1)-dimensional Ito equation
Authors: Tang Yaning , Ma Jinli , Xie Wenxian , Zhang Lijun
Published: April 2019

In this paper, two classes of interaction solutions of the (2[Formula: see text]+[Formula: see text]1)-dimensional Ito equation are studied in the case of Hirota bilinear form. As the results, the interaction solutions between the rational function and a periodic function as well as the interaction solution between the hyperbolic function and a periodic function are obtained. Based on the interaction solutions, a new transformation is proposed to analyze and discuss the influence of parameters. Furthermore, two kinds of lump solutions can be obtained via the limit behavior of the interaction solutions and the dynamical properties of these solutions are also illustrated.
Study on the Structural Parameters and Response Characteristics of the Tilted Antenna of Directional Electromagnetic Wave Resistivity Measuring Instrument
Authors: Xie Xicao , Wu Jie
Published: April 2019

The directional logging-while-drilling measurements enable to monitor the distance to formation boundaries and their orientation and facilitate proactive well placement, and thus can provide directionality information useful in detecting physical parameters such as bed boundaries, formation dip and formation azimuth, so the oil and gas recovery can be greatly improved. The characteristics of a kind of electromagnetic wave resistivity logging while drilling (LWD) tool with tilted antennas are computed via the magnetic-current-source dyadic Green’s function for horizontally stratified anisotropic media. The current characteristic at the formation interface of the tilted antennas is compared with that of the axial antenna, and how the LWD tool with tilted antennas to detect the formation interface position and orientation is revealed. The amplitude-attenuation and phase-shift characteristics of LWD tool with tilted antennas are analyzed, and how to design the angle of tilted antenna is presented. The relationship between the emitting frequency and emitting-receiving antenna space parameters is expounded, and the emitting-receiving antenna space parameter suitable for different frequencies is presented. The detection characteristic of the electromagnetic wave measuring instrument is studied. For the highly deviated well formation model, the directional response characteristics of the different relative dip angle isotropic and anisotropic formation are numerically simulated and analyzed. The directional response characteristics of the two kinds of coil arrangement (unilateral arrangement and symmetrical arrangement) are analyzed by numerical simulation, and the solution to reduce or eliminate the influence of the directional response of the isotropy on the directional response is obtained. The conclusions obtained by theoretical analysis and numerical simulation provide a guide for the instrument principle research and application.
A Statistical Test Generation Based on Mutation Analysis for Improving the Hardware Trojan Detection
Authors: Liu Yanjiang , Zhao Yiqiang , He Jiaji , Xin Ruishan
Published: April 2019

Hardware Trojan has become a major threat to the security and trustworthiness of integrated circuit (IC) employed in critical applications. Due to the presence of process variations and measurement noises, all existing side-channel Trojan detection approaches suffer from low detection sensitivity or even false negatives with increasing circuit size and decreasing Trojan size. In this paper, we propose a statistical test generation approach based on mutation analysis, which generates a set of test vectors aiming at activating the hardware Trojan inserted into the low activity nodes. Such approach not only enhances the controllability of low activity nodes through increasing the switching activity of it, but also improves the observability by propagating the artificial designed errors introduced by the mutant to the outputs. Simulation results of a set of ISCAS’85 and ISCAS’89 benchmark circuits show that the proposed approach improves the activity of low activity nodes 463% at most compared with the Multiple Excitation of Rare Occurrence (MERO) approach and increases the Trojan coverage with 84.08% reduction in test length. Moreover, the test vectors generated by the proposed approach and the MERO approach, respectively, are exerted to the circuit under test. Experimental results demonstrate that the Mahalanobis distance margin of the proposed approach is much greater than the MERO approach, and thus provide a comparable robustness with decreasing Trojan size.
Novel Monopole Microstrip Antennas for GPS, WiMAX and WLAN Applications
Authors: Bag Biplab , Biswas Priyabrata , Biswas Sushanta , Sarkar Partha Pratim , Ghoshal Dibyendu
Published: April 2019

In this paper, two novel low-profile monopole antennas are presented for simultaneous operation in GPS (Global Positioning System), WLAN (Wireless Local Area Network) and WiMAX (Worldwide Interoperability for Microwave Access) applications. The antennas constitute of a T-shaped microstrip feed line and directly coupled strips to generate multiple bands. The proposed antennas are printed on one side of a low-cost FR4 epoxy substrate and partial ground plane (metal plane is etched partially) are fabricated on the other side of the substrate. The overall dimension of antenna is [Formula: see text][Formula: see text]mm3. Measured results show that the antenna1 (quad band) covers the four distinct operating bands of 320[Formula: see text]MHz (2.17–2.49[Formula: see text]GHz), 190[Formula: see text]MHz (3.31–3.50[Formula: see text]GHz), 270[Formula: see text]MHz (5.18–5.45[Formula: see text]GHz) and 700[Formula: see text]MHz (5.5–6.20[Formula: see text]GHz). Antenna2 (penta band) covers the frequency bands of 1.29–1.98[Formula: see text]GHz (center frequency 1.61[Formula: see text]GHz), 2.78–2.91[Formula: see text]GHz (center frequency 2.83[Formula: see text]GHz), 3.59–3.94[Formula: see text]GHz (center frequency 3.75[Formula: see text]GHz), 5.15–5.33[Formula: see text]GHz (center frequency 5.24[Formula: see text]GHz) and 5.39–6.06[Formula: see text]GHz (center frequency 5.56[Formula: see text]GHz). The detail antenna design and parametric analyses are discussed in steps. The characteristic of radiation pattern and gain are measured. The measured and simulated results are in good agreement. The antennas are designed using a simulation software HFSS v.15.
Pattern Dynamics of a Diffusive Toxin Producing Phytoplankton–Zooplankton Model with Three-Dimensional Patch
Authors: Jia Dongxue , Zhang Tonghua , Yuan Sanling
Published: April 2019

In this paper, the Turing pattern formation in a diffusive toxin producing phytoplankton–zooplankton model with three-dimensional patch is investigated. Firstly, the conditions for the existence of Hopf bifurcation and stationary pattern are obtained based on the linear stability analysis. Then, the amplitude equations are derived by using nonlinear analysis and standard multiple-time-scale analysis. This study shows that there exists a pattern transition from spot pattern to stripe pattern with the decrease of the amount of toxicity, and the death rate of zooplankton also has a significant effect on the pattern structure. The obtained results suggest that the toxicity of phytoplankton and the death rate of zooplankton both play vital roles in the spatial distribution of population density.
Flip-Flip Bifurcation in a Mathematical Cardiac System
Authors: Kitajima Hiroyuki , Yazawa Toru
Published: April 2019

We study the intersection of double-flip (period-doubling) bifurcations in a parameter plane. We derive normal forms for discrete-time and continuous-time systems. Using these normal forms, we clarify the bifurcation structure around the flip-flip bifurcation point. We apply these analytical results to a system of coupled ventricular cell models. We determine the coexistence of in-phase and anti-phase two-periodic solutions. We make the simplest model for generating discordant alternans and clarify that two parameters (free concentration of potassium ions in the extracellular compartment and the conductance of the gap junction) play key roles in generating discordant alternans.
Smale Horseshoe in a Piecewise Smooth Map
Authors: Li Denghui , Chen Hebai , Xie Jianhua
Published: April 2019

We investigate the chaotic dynamics of a two-dimensional piecewise smooth map. The map represents the normal form of a discrete time representation of impact oscillators near grazing states. It is proved that, in certain region of the parameter space, the nonwandering set of the map is contained in a bounded region and that, restricted to the nonwandering set, the map is topologically conjugate to the two-sided shift map on two symbols.
On a One-Parameter Discrete-Time Z4-Equivariant Cubic Dynamical System
Authors: Gritsans Armands
Published: April 2019

The lemniscate sine and cosine are solutions of a [Formula: see text]-equivariant planar Hamiltonian system for all of which nontrivial solutions are nonhyperbolic periodic orbits. The forward Euler scheme is applied to this system and the one-parameter discrete-time [Formula: see text]-equivariant cubic dynamical system is obtained. The discrete-time system depending upon a parameter exhibits rich dynamics: numerical simulation shows that the system has attracting closed invariant curves, multiple periodic orbits and attracting sets exhibiting chaotic behavior. The approximating system of ordinary differential equations is constructed. We discuss the existence of closed invariant curves for the discrete-time system.
Hopf Bifurcation in a Delayed Diffusive Leslie–Gower Predator–Prey Model with Herd Behavior
Authors: Zhang Fengrong , Li Yan , Li Changpin
Published: April 2019

In this paper, we consider a delayed diffusive predator–prey model with Leslie–Gower term and herd behavior subject to Neumann boundary conditions. We are mainly concerned with the impact of time delay on the stability of this model. First, for delayed differential equations and delayed-diffusive differential equations, the stability of the positive equilibrium and the existence of Hopf bifurcation are investigated respectively. It is observed that when time delay continues to increase and crosses through some critical values, a family of homogeneous and inhomogeneous periodic solutions emerge. Then, the explicit formula for determining the stability and direction of bifurcating periodic solutions are also derived by employing the normal form theory and center manifold theorem for partial functional differential equations. Finally, some numerical simulations are shown to support the analytical results.
Multistability and Hidden Attractors in the Dynamics of Permanent Magnet Synchronous Motor
Authors: Singh Jay Prakash , Roy Binoy Krishna , Kuznetsov Nikolay V.
Published: April 2019

This paper attempts to find some interesting and unique properties in the dynamics of a permanent magnet synchronous motor (PMSM). When compared with the existing literature on the dynamics of a PMSM, we find some interesting and unique behaviors which have not been reported so far. These are (i) occurrence of multistability, (ii) existence of hidden attractors and (iii) equilibrium point with two stable node-foci and one saddle point index-1. The above-said unique behaviors in the dynamics of a PMSM are not found in the literature to the best of authors’ knowledge. Three different cases with (a) [Formula: see text] (voltage/frequency) control, (b) constant load torque and (c) constant direct and quadrature-axis voltage, and load torque are considered to show the multistability in the dynamics of a PMSM. The multistability is confirmed by using the bifurcation analysis. In another case, when the load torque is selected as a feedback of quadrature-axis voltage, the system depicts hidden attractors (point, periodic and transient chaotic). An adaptive sliding mode control is designed to control the hidden transient chaotic behavior of the system. The simulation results confirm the suppression of the transient chaotic attractors with smaller stabilization time and chattering free control input.
Phase Space Analysis of the Nonexistence of Dynamical Matching in a Stretched Caldera Potential Energy Surface
Authors: Katsanikas Matthaios , Wiggins Stephen
Published: April 2019

In this paper, we continue our studies of the two-dimensional caldera potential energy surface in a parametrized family that allows for a study of the effect of symmetry on the phase space structures that govern how trajectories enter, cross, and exit the region of the caldera. As a particular form of trajectory crossing, we are able to determine the effect of symmetry and phase space structure on dynamical matching. We show that there is a critical value of the symmetry parameter which controls the phase space structures responsible for the manner of crossing, interacting with the central region (including trapping in this region) and exiting the caldera. We provide an explanation for the existence of this critical value in terms of the behavior of the Hénon stability parameter for the associated periodic orbits.
Cosmological Einstein–Maxwell model with g-essence
Authors: Razina Olga , Tsyba Pyotr , Meirbekov Bekdaulet , Myrzakulov Ratbay
Published: April 2019

In this paper, we study the model of the late universe with the homogeneous, isotropic and flat Friedmann–Robertson–Walker metric, where the source of the gravitational field is based on the fermion and boson fields, with the Maxwell term [Formula: see text] in four dimensions. The actuation of the Maxwell term for the Einstein gravity makes it possible to find new approaches to solve the problem of the observed accelerated expansion of the universe. Energy conditions have been obtained and studied. These conditions impose very simple and model-independent restrictions on the behavior of energy density and pressure since they do not require a specific equation-of-state of matter. To consider the model, the energy conditions NEC, WEC, DEC are realized, and the SEC condition is violated. The boson and fermion fields are responsible for the accelerated regime at early times, but since the total pressure tends toward zero for large times, a transition to a decelerated regime occurs. Maxwell field is crucial only in the early times.
Design of Tuneable Vibration Absorber by Using Inertial Actuator with Proof-Mass Acceleration Feedback
Authors: Mao Qibo , Huang Shizuo
Published: April 2019

This study is concerned with design of a tuneable vibration absorber by using an inertial actuator (IA) with its proof-mass acceleration used as feedback signal. Acceleration feedback control loop can produce virtual mass effect, and the natural frequency of the IA can be shifted. The main advantage of the proposed IA-based tuneable vibration absorber is that the control loop is very simple and does not require any low-pass filter or integrator. Finally, the experimental results are presented to verify the tuning capability and control performance of the proposed vibration absorber.
Discrete Distribution for the Stochastic Range of a Wiener Process and Its Properties
Authors: El-Hadidy Mohamed Abd Allah
Published: April 2019

We introduce the discrete distribution of a Wiener process range (DDWPR). Rather than finding some basic distributional properties including hazard rate function, moments, stress-strength parameter and order statistics of this distribution, this paper studies some basic properties of the truncated version of this distribution. The effectiveness of this distribution is established using a data set.
A class of linear codes of length 2 over finite chain rings
Authors: Cao Yonglin , Cao Yuan , Dinh Hai Q. , Fu Fang-Wei , Gao Jian , Sriboonchitta Songsak
Published: April 2019

Let [Formula: see text] be a finite field of cardinality [Formula: see text], where [Formula: see text] is an odd prime, [Formula: see text] be positive integers satisfying [Formula: see text], and denote [Formula: see text], where [Formula: see text] is an irreducible polynomial in [Formula: see text]. In this note, for any fixed invertible element [Formula: see text], we present all distinct linear codes [Formula: see text] over [Formula: see text] of length [Formula: see text] satisfying the condition: [Formula: see text] for all [Formula: see text]. This conclusion can be used to determine the structure of [Formula: see text]-constacyclic codes over the finite chain ring [Formula: see text] of length [Formula: see text] for any positive integer [Formula: see text] satisfying [Formula: see text].
Overestimation Analysis of Interval Finite Element for Structural Dynamic Response
Authors: Li Tuanjie , Dong Hangjia , Zhao Xi , Tang Yaqiong
Published: April 2019

Dynamic response analysis plays an important role for the structural design. For engineering structures, there exist model inaccuracies and structural parameters uncertainties. Consequently, it is necessary to express these uncertain parameters as interval variables and introduce the interval finite element method (IFEM), in which the elements in stiffness matrix, mass matrix and damping matrix are all the function of interval parameters. The dependence of interval parameters leads to overestimation of dynamic response analysis. In order to reduce the overestimation of IFEM, the element-based subinterval perturbation for static analysis is applied to dynamic response analysis. According to the interval range, the interval parameters are divided into different subintervals. With permutation and combination of each subinterval, the upper and lower bounds of displacement response are obtained. Because of the large number of degrees of freedom and uncertain parameters, the Laplace transform is used to evaluate the dynamic response for avoiding to frequently solve the interval finite element linear equations. The numerical examples illustrate the validity and feasibility of the proposed method.
Nonlinear Large Deformation of Graphene Sheets Using a Nonlocal-Based ANCF Method
Authors: Wang Qingtao , Zhao Zhen , Zhang Yang , Pang Zhaojun , Niu Fuzhou
Published: April 2019

A novel nonlinear model of single-layered graphene sheets (SLGSs) subject to large deformation is proposed using the absolute nodal coordinate formulation (ANCF) and the nonlocal elasticity theory. The geometrical definition of SLGSs is described by ANCF thin plate element while the strain energy is expressed by nonlocal theory. Then, the formulation of elastic force and the Jacobian of the elastic force is derived. We verify the proposed model by comparing the results with other published results and conduct corresponding numerical case study to clarify the influence of boundary conditions (BCs), nonlocal parameters, side length and aspect ratio. Large deformation problem of SLGSs with several BCs and different loading modes are simulated to study the mechanical nonlinearity of the SLGSs.