Triangle Structure Research Articles

Rotating Corrected-Based Cavitation Model for a Centrifugal Pump

Cavitation has bothered the hydraulic machinery for centuries, especially in pumps. It is essential to establish a solid way to predict the unsteady cavitation evolution with considerable accuracy. A novel cavitation model was proposed, considering the rotating motion characteristic of centrifugal pump. Comparisons were made with three other cavitation models and validated by experiments. Considerable agreements can be noticed between simulations and tests. All cavitation models employed have similar performance on predicting the pump head drop curve with proper empirical coefficients, and also the unsteady cavitation evolution was well solved. The proposed rotating corrected-based cavitation model (rotating based Zwart-Gerber-Belamri (RZGB)) obtained identical triangle cavity structure with the experiment visualizations, while the others also got triangle structure but with opposite direction. The maximum flow velocity in the impeller passage appears near the shroud, contributing to the typical triangle cavity structure. A preprocessed method for instant rotating images was carried out for evaluating the erosion risk area in centrifugal pump, based on the standard deviation of gray level. The results imply that the unsteady rear part of the attached cavity is vulnerable to be damaged, where the re-entrant flow was noticed. This work presented a suitable cavitation model and reliable numerical simulation approach for predicting cavitating flows in centrifugal pump.

Direct fabricating large-area nanotriangle structure arrays on tungsten surface by nonlinear lithography of two femtosecond laser beams.

Two-dimensional arrays of periodic nanostructures are fabricated on bulk tungsten surface within a single step using collinear propagation of two time-delayed femtosecond laser beams with orthogonal polarizations. It is surprisingly found that the geometric profile of the structure unit exhibits a triangle shape in hundred nanometer scales, and its spatial dimension can be modulated by the ambient air pressure ranging from 1 atm to 10-3 Pa. As the ambient air pressure decreases, the obtained surface structures display a large depth covered with nanowires. Physically, the formation of such triangle structures is originated from the transient physical correlations between the two laser-matter interaction processes, and also affected by the heat transfer effects of the surrounding air. In addition, the experimental measurements reveal that the minimum reflectivity of the nanotriangle surface structures is unprecedentedly reduced to as low as ~2.9% especially within the visible-infrared range.

Coordination Reactions of 5-(2-(4-Bromophenyl)ethynyl)pyrimidine in On-Surface Synthesis

The coordination reactions of 5-(2-(4-bromophenyl)ethynyl)pyrimidine (PEPmBr) molecules on Ag(111) was studied by low-temperature scanning tunneling microscopy (LT-STM). First, vapor deposition of PEPmBr molecules onto Ag(111) at room temperature leads to the formation of a large-scale pinwheel-like self-assembly structure. Then hierarchical coordination reactions were employed to synthesize organometallic dimers and tetramers on Ag(111) surface. In contrast to the releasing of the coordinated Ag atoms and forming covalent bonds, it is found herein that further thermal activation induces the rotation of the C–Ag–C and N–Ag–N coordination bonds, resulting in various organometallic nanoteris with triangle, rectangle, and zigzag structures.

Electromagnetic resonance in the asymmetric terahertz metamaterials with triangle microstructure

We investigate terahertz transmission properties and electromagnetic resonance modes in the asymmetric triangle structures with the change of asymmetric distance and the direction of electric field. When the THz electric field is perpendicular to the split gap of triangle, the electric field can better excite the THz absorption in the triangle structures. Importantly, electromagnetically induced transparency (EIT) characteristics are observed in the triangle structures due to the destructive interference of the different excited modes. The distributions of electric field and surface current density simulated by finite difference time domain indicate that the bright mode is excited by the side of triangle structures and dark mode is excited by the gap-side of triangle. The present study is helpful to understand the electromagnetic resonance in the asymmetric triangular metamaterials.

A density functional theory study on the structural and electronic properties of PbxSbySez(x+y+z= 2, 3) clusters

The structural and electronic properties of neutral ternary PbxSbySezclusters (x + y + z = 2, 3) in their ground states have been explored by means of density functional theory calculations. The geometric structures and binding energies are systematically explored and for the most stable configurations of each cluster type vibrational frequencies, charges on atoms, energy difference between highest occupied and lowest unoccupied molecular orbitals, and the possible dissociations channels have been analyzed. Depending on being binary or ternary cluster and composition, the most energetic structures have singlet, doublet or triplet ground states, and trimers prefer to form isosceles, equilateral or scalene triangle structure.

Coordination-driven self-assembly of chiral palladium(ii)-based supramolecular triangle structures

Chiral structures of palladium(ii)-based triangular supramolecular complexes, with achiral corners and edges, have been characterized in solution.

Resolving the Structure of a Well-Ordered Hydroxyl Overlayer on In2O3(111): Nanomanipulation and Theory.

Changes in chemical and physical properties resulting from water adsorption play an important role in the characterization and performance of device-relevant materials. Studies of model oxides with well-characterized surfaces can provide detailed information that is vital for a general understanding of water–oxide interactions. In this work, we study single crystals of indium oxide, the prototypical transparent contact material that is heavily used in a wide range of applications and most prominently in optoelectronic technologies. Water adsorbs dissociatively already at temperatures as low as 100 K, as confirmed by scanning tunneling microscopy (STM), photoelectron spectroscopy, and density functional theory. This dissociation takes place on lattice sites of the defect-free surface. While the In2O3(111)-(1 × 1) surface offers four types of surface oxygen atoms (12 atoms per unit cell in total), water dissociation happens exclusively at one of them together with a neighboring pair of 5-fold coordinated In atoms. These O–In groups are symmetrically arranged around the 6-fold coordinated In atoms at the surface. At room temperature, the In2O3(111) surface thus saturates at three dissociated water molecules per unit cell, leading to a well-ordered hydroxylated surface with (1 × 1) symmetry, where the three water OWH groups plus the surface OSH groups are imaged together as one bright triangle in STM. Manipulations with the STM tip by means of voltage pulses preferentially remove the H atom of one surface OSH group per triangle. The change in contrast due to strong local band bending provides insights into the internal structure of these bright triangles. The experimental results are further confirmed by quantitative simulations of the STM image corrugation.

The microstructure, strain state and optical properties of FePt nano-clusters in MgO matrix

The FePt nano-clusters (NCs): MgO nanocomposite films were successfully fabricated by pulsed laser deposition at 650 °C. In-situ reflection high-energy electron diffraction (RHEED) analysis indicates the existence of epitaxial strain in the FePt cluster. This strain was identified quantitatively (1.2% and 0.66% at in-plane and out-of-plane direction) via strain mapping by geometric phase analysis (GPA) at nano-scale. A further microstructure investigation by transmission electron microscopy (TEM) shows the lop-angle triangle structure of FePt NCs, which is considered to be caused by the strain difference in two directions. Two absorption peaks has been observed in the range of 4–6.5 eV by ultraviolet–visible, which were attributed to the existence of grain boundary and defects caused by the embedding of FePt in MgO. This work provided important information for its further research and performance improvement in many potential applications.

Effect of molecular architecture on morphology in the nanostructures and its applications in superhydrophobicity and organic photovoltaics

Morphological structures with respect to the effect of carbazole derivatization, which are based on conjugated donor–acceptor moieties, are presently explored. In this work, light management studies, organic photovoltaics devices and surface properties are systematically investigated. Two carbazole derivatives Cz–Bt (carbazole–benzothiadiazole) and Cz–Bt–BT (carbazole–benzothiadiazole–bithiophene) are electrosprayed, resulting in triangle and spike (2-D and 3-D pyramids) structures, respectively. These 2-D and 3-D pyramids differ due to an additional bithiophene unit at the molecular level, which has imparted a higher degree of rotational freedom. The effects of derivatives, solution concentrations and solvents vapor pressure on morphology are studied. Further, these submicron-size pyramids are characterized by enhancement in light absorption due to scattering and multi-reflection. It is observed that 2-D pyramids enhance up to 44.4%, whereas 3-D pyramids enhance up to 18.7% of light absorption. Subsequently, these structures are characterized in organic photovoltaics architecture, using various layer design strategies, and, thus, we able to obtain insights about layer addition, with respect to structures size and morphology. In addition, the effect of fabrication procedure assisting in an increase in hydrophobicity is also demonstrated.

Families of Rational Solutions of Order 5 to the KPI Equation Depending on 8 Parameters

In this paper, we go on with the study of rational solutions to the Kadomtsev-Petviashvili equation (KPI). We construct here rational solutions of order 5 as a quotient of 2 polynomials of degree 60 in x, y and t depending on 8 parameters. The maximum modulus of these solutions at order 5 is checked as equal to 2(2N + 1)2 = 242. We study their modulus patterns in the plane(x, y) and their evolution according to time and parameters a1, a2, a3, a4, b1, b2, b3, b4. We get triangle and ring structures as obtained in the case of the NLS equation.

Nuclear cluster structure effect on elliptic and triangular flows in heavy-ion collisions

The initial geometry effect on collective flows, which are inherited from initial projectile structure, is studied in relativistic heavy-ion collisions of $^{12}$C + Au by using a multi-phase transport model (AMPT). Elliptic flow ($v_2$) and triangular flow ($v_3$) which are significantly resulted from the chain and triangle structure of $^{12}\mathrm{C}$ with three-$\alpha$ clusters, respectively, in central $^{12}\mathrm{C}$+$^{197}\mathrm{Au}$ collisions are compared with the flow from the Woods-Saxon distribution of nucleons in $^{12}\mathrm{C}$. $v_3/v_2$ is proposed as a probe to distinguish the pattern of $\alpha$-clustered $^{12}\mathrm{C}$. This study demonstrates that the initial geometry of the collision zone inherited from nuclear structure can be explored by collective flow at the final stage in heavy-ion collisions.

Effect of surface texture on the transverse vibration for sawing

The transverse vibration of bandsaw blade in the sawing process is a well-known cause of material loss, bandsaw wear, and poor surface quality of workpiece. Five types of surface textures with inverted triangle structure on blade of bandsaw were developed to study their influences on the transverse vibration for sawing. These surface textures with the same total area were designed to identical size with different depths and identical depth with multiple sizes, respectively. The experiments on sawing 45# steels showed that the surface textured bandsaw could reduce the root mean square error (RMSE) of the lateral force by 38.22~48.42% in time domain. Compared with the non-textured bandsaw, the reduction occurred between 300 and 400 Hz in frequency domain. It was probably due to the different effects of dynamic pressure produced by cutting fluids in surface texture. In addition, the textures with the depth to diameter ratio δ = 0.01 showed the best result in this study.

Roles of clustering properties for degree-mixing pattern networks

The clustering coefficients have been extensively investigated for analyzing the local structural properties of complex networks. In this paper, the clustering coefficients for triangle and square structures, namely [Formula: see text] and [Formula: see text], are introduced to measure the local structure properties for different degree-mixing pattern networks. Firstly, a network model with tunable assortative coefficients is introduced. Secondly, the comparison results between the local clustering coefficients [Formula: see text] and [Formula: see text] are reported, one can find that the square structures would increase as the degree [Formula: see text] of nodes increasing in disassortative networks. At the same time, the Pearson coefficient [Formula: see text] between the clustering coefficients [Formula: see text] and [Formula: see text] is calculated for networks with different assortative coefficients. The Pearson coefficient [Formula: see text] changes from [Formula: see text] to 0.98 as the assortative coefficient [Formula: see text] increasing from [Formula: see text] to 0.45, which suggests that the triangle and square structures have the same growth trend in assortative networks whereas the opposite one in disassortative networks. Finally, we analyze the clustering coefficients [Formula: see text] and [Formula: see text] for networks with tunable assortative coefficients and find that the clustering coefficient [Formula: see text] increases from 0.0038 to 0.5952 while the clustering coefficient [Formula: see text] increases from 0.00039 to 0.005, indicating that the number of cliquishness of the disassortative networks is larger than that of assortative networks.

A Compact Triangular Slot Array Multiband Antenna for Wireless Applications

A novel compact triangular slot array multi-broadband planar antenna is proposed for mobile handsets in the paper. The antenna has an inverted triangle structure radiator with fourteen units triangular slot array and coplanar waveguide (CPW) feed structure. The antenna can cover more than ten mobile applications in three broad-bands with -10dB bandwidth of 69.57% (0.613-1.267GH) for UHF (606-806MHz), GSM900 (880-960MHz), LTE44 (703-803MHz), CDMA2000 (825-880,885-960MHz), 30.17% (1.97-2.67GHz) for DCS1800 (1710-1880MHz),TD-SCDMA (1880-2025MHz,2300-2400MHz), WCDMA (1920-2170MHz,1755-1880MHz), LTE33-41 (1900-2690MHz), Bluetooth, GPS, COMPASS, GLONSS, GALILEO, WLAN (802.11b/g/n:2.4-2.48GHz), and 31.17%(4.17-5.71GHz) for WLAN (802.11a/n:5.15-5.35GHz) wireless applications. The antenna is fabricated on a 1.6 mm-thick FR4 substrate with dielectric constant of 4.4, and the size is 60*55mm2. The good agreement between the measurement results and the simulation validates the proposed design approach and meets the requirements for various wireless applications.

Efficient Vector Influence Clustering Coefficient Based Directed Community Detection Method

Community detection algorithms are important for determining the character statistics of complex networks. Compared with the conventional community detection algorithms, which always focus on undirected networks, our algorithm is concentrated on directed networks such as the WeChat moments relationship network and the Sina Micro-Blog follower relationship network. To address disadvantages such as lower execution efficiency and higher deviation of precision that current directed community detection algorithms always have, we propose a new approach that is based on the triangle structure of community basis and modeled on the local information transfer process to precisely detect communities in directed networks. Based on the directed vector theory in probability graphs and the dynamic information transfer gain (ITG) of vertices in directed networks, we propose the novel ITG method and the corresponding target optimal function for evaluating the partition quality in a community detection algorithm. Then, we combine ITG and the target function to create the new community detection algorithm ITG-directed weighted community clustering for directed networks. With extensive experiments using artificial network data sets and large, real-world network data sets derived from online social media, our algorithm proved to be more accurate and faster in directed networks than several traditional, well-known community detection methods, such as FastGN, order statistics local optimization method, and Infomap.

Compact ultra‐wideband fractal monopole antenna with high gain using single layer superstrate

ABSTRACTA novel technique is applied on fractal monopole antenna to enhance gain for ultra wideband (UWB) applications. The fringing field effect of the antenna is increased by using dielectric superstrate, and it is designed by fabricating rectangular conductor on single side of the superstrate with dimension 10 × 21.5 mm2. The fractal structure is designed by the identical triangle structure in the radiating patch. The dielectric superstrate is placed on the fractal monopole antenna. At the time of feeding, the conductor of the superstrate is connected through ground plane of the antenna. The overall dimension of the fractal monopole antenna with superstrate is 24.5 × 21.6 × 3.15 mm3. The measurement result of the reflection coefficient is below −10 dB indicating impedance bandwidth of 3.1 to 11 GHz. The measured radiation patterns are also improved and peak gain of the conventional antenna increases approximately 1.6 dB by using superstrate with reference to conventional design. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:482–488, 2017

The Maker-Platform Eco-system Model in Internet Environment: A Case Study of Haier

Enterprises can adapt themselves to a dynamic environment by conducting product innovation and management innovation. In this paper, however, we think that enterprises have to engage in management innovation, but not merely product innovation in Internet environment. In case study of Haier, we conclude that its management innovation process, which experiencing bureaucracy triangle structure, inverted triangle structure, eventually maker-platform eco-system mode, meeting the requirements of the Internet environment. As three key nodes of the maker-platform eco-system, open-source platform provide resources for the existence of eco-system, diversified small-micro businesses offer the ecosystem with vitality and Internet facility is essential to upgradation of the ecosystem. At last, we discuss the potential implications of this new model to transformation of large businesses and establishment of maker-platform, as well as some issues that may hinder the positive effects of this model.

Creation and measurement of broadband squeezed vacuum from a ring optical parametric oscillator.

We report a 65 MHz-bandwidth triangular-shaped optical parametric oscillator (OPO) for squeezed vacuum generation at 860 nm. The triangle structure of our OPO enables the round-trip length to reach 45 mm as a ring cavity, which provides a counter circulating optical path available for introducing a probe beam or generating another squeezed vacuum. Hence our OPO is suitable for the applications in high-speed quantum information processing where two or more squeezed vacua form a complicated interferometer, like continuous-variable quantum teleportation. With a homemade, broadband and low-loss homodyne detector, a direct measurement shows 8.4 dB of squeezing at 3 MHz and also 2.4 dB of squeezing at 100 MHz.

PROPER AFFINE DEFORMATIONS OF THE ONE-HOLED TORUS

A Margulis spacetime is a complete at Lorentzian 3-manifold M with free fundamental group. Associated to M is a noncompact complete hyperbolic surface ∑ homotopy-equivalent to M. The purpose of this paper is to classify Margulis spacetimes when ∑ is homeomorphic to a one-holed torus. We show that every such M decomposes into polyhedra bounded by crooked planes, corresponding to an ideal triangulation of ∑. This paper classifies and analyzes the structure of crooked ideal triangles, which play the same role for Margulis spacetimes as ideal triangles play for hyperbolic surfaces.

Fluorescent incisionless cholangiography as a teaching tool for identification of Calot's triangle.

Intraoperative incisionless fluorescent cholangiogram (IOIFC) has been demonstrated to be a useful tool to increase the visualization of Calot's triangle. This study evaluates the identification of extrahepatic biliary structures with IOIFC by medical students and surgery residents. Two pictures were taken, one with xenon light and one with near-infrared (NIR) light, at the same stage during dissection of Calot's triangle in ten different cases of laparoscopic cholecystectomy (LC). All twenty pictures were organized in a random fashion to remove any imagery bias. Twenty students and twenty residents were asked to identify the biliary anatomy. Medical students were able to accurately identify the cystic duct on an average 33.8% under the xenon light versus 86% under NIR light (p=0.0001), the common hepatic duct (CHD) on an average 19% under the xenon light versus 88.5% under NIR light (p=0.0001), and the junction on an average 24% under xenon light versus 80.5% under NIR light (p=0.0001). Surgery residents were able to accurately identify the cystic duct on an average 40% under the xenon light versus 99% under NIR light (p=0.0001), the CHD on an average 35% under the xenon light versus 96% under NIR light (p=0.0001), and the junction on an average 24% under the xenon light versus 95.5% under NIR light (p=0.0001). IOIFC increases the visualization of Calot's triangle structures when compared to xenon light. IOIFC may be a useful teaching tool in residency programs to teach LC.