Zigzag Arrangement Research Articles

COVID-19 실내 확산 방지를 위한 급배기 특성 CFD 분석

The outbreak of COVID-19 still seriously affects our daily lives despite the actions with governmental level to prevent the situation from getting worse. Among various infection routes of COVID-19, airborne spread needs to be carefully handled in the perspective of HVAC. In particular, cluster infection in multi-use facilities which unspecified number of people use is now the big issue. One of the most simple solution is to dilute virus pollution through the proper ventilation. Therefore, this study analyzes the effect of the location of diffusers and the ventilation rate on the indoor air distribution in the large space through a numerical method. The results show that the zigzag arrangement was the most suitable for ventilation because of its high average and minimum air velocity.

RETRACTED: The effect of the zigzag arrangement of lithium-ion batteries inside the air duct of an office building for heating and evaluation of the impact of the number of air outlets in different seasons of the year

This paper examines a hybrid battery system for heating an office building. Lithium cells have been one of the most common devices with high energy storage. However, the heat generated when they are placed close to each other has been a significant problem in these systems. A system is designed in this paper to use heat for heating a residential unit. The battery packs are placed inside the air duct, and each pack has 81 batteries 18,650. The batteries are arranged in a zigzag pattern. The airflow passes through the batteries, cools the batteries, and then is directed into the building. For each floor of the building, one of the ventilation units is considered with a battery. The model with three outlets causes the highest maximum temperature (TMax) of battery cells and the minimum heat transfer coefficient (HETC) among different models, while the 1-outlet one has the lowest TMax of battery cells and the maximum HETC. However, using the single-outlet model leads to the maximum pressure drop (ΔP), and the outlet air has the minimum temperature. At the same time, using the three-outlet model creates the minimum ΔP, and the outlet air temperature (TOutlet) has the maximum value. The model with 3 outlets can reduce the required heating energy consumption (ENC) by 23% in spring.

Wave attenuation by multiple slotted barriers with a zig-zag arrangement -A physical and numerical approach

In the present study, scattering of surface gravity waves by multiple slotted vertical barriers arranged in a zig-zag manner is analyzed by employing Computational Fluid Dynamics (CFD) and validated with physical model tests. The porosity of the vertical slotted barrier is varied from 10% to 40%, and the number of slotted barriers varied from 1 to 6. The results from CFD correlate well with the laboratory measurements on the scattering coefficients for a wide range of input conditions giving a high level of confidence. For relatively short waves (h/λ > 0.3, h- water depth and λ- wave length), slotted barriers up to 3 numbers and porosity from 20% to 30% are required to achieve wave transmission coefficient in the range of 0.2 to 0.3. For relatively long waves (h/λ < 0.3), slotted barriers of 5 to 6 numbers and porosity in the range of 10% to 20% are needed to obtain wave transmission of 0.2 to 0.3. The results presented in this study can be used for a wide range of wave damping applications in the field of coastal engineering.

Effect of Manufacturing Tolerance in Flow Past a Compressor Blade

Abstract This paper presents the effect of manufacturing tolerance on performance and stability boundaries of a transonic fan using a Reynolds-averaged Navier–Stokes simulation. The effects of tip gap and stagger angle variations were analyzed through a series of single passage and double passage simulation; based on which an optimal arrangement was proposed for random tip gap and random stagger angle variation for a whole annulus rotor. All simulations were carried out using NASA rotor 67 as a test case and AU3D as an in-house computational fluid dynamics solver. Results illustrate that the stagger angle variation mainly affects efficiency and its circumferential variation must be as smooth as possible. Furthermore, the tip gap variation affects the stability boundary as well as performance and its optimal configuration mandates a zigzag arrangement of blades around the annulus, i.e., larger tip gap between two smaller ones.

Influence of the Different Types of Auxiliary Noncarboxylate Organic Ligands on the Topologies and Magnetic Relaxation Behavior of Zn-Dy Heterometallic Single Molecule Magnets.

In this work, we first synthesized a Zn-Dy complex, [Zn6Dy2(L)6(tea)2(CH3OH)2]·6CH3OH·8H2O (H2L = N-3-methoxysalicylidene-2-amino-3-hydroxypyridine, teaH3 = triethanolamine, 1), by employing H2L, anhydrous ZnCl2, and Dy(NO3)3·5H2O reacting with auxiliary ligand teaH3 in the mixture of CH3OH and DMF. When teaH3 and the solvent CH3OH in the reaction system of 1 were replaced by the auxiliary ligand 2,6-pyridinedimethanol (pdmH2) and the solvent MeCN, another Zn-Dy complex, [Zn4Dy4(L)6(pdm)2(pdmH)4]·10CH3CN·5H2O (2), was obtained. For 1, its crystal structure can be viewed as a dimer of two Zn3DyIII units. However, for 2, four DyIII form a zigzag arrangement, and each of its terminals linked two ZnII ions. Interestingly, although the structural topologies of 1 and 2 are different, the coordination geometries of DyIII in 1 and 2 are all triangular dodecahedron (TDD-8). The difference is that the continuous shape measure (CShM) values of DyIII in 1 are larger than the corresponding values in 2. Magnetic investigation revealed that the diluted sample 1@Y exhibits two magnetic relaxation processes, while 2 only exhibits a single relaxation process. Ab initio calculations indicated that, in the crystal lattice of 1, two complexes exhibiting slightly different CShM values of DyIII result in the double relaxation behavior of 1@Y. However, for 2, one of two DyIII fragments possesses a fast quantum tunneling of magnetization (QTM), resulting in its magnetic process presented at T < 1.8 K, so 2 exhibits single relaxation behavior. More importantly, the theoretical calculations also clearly indicated that the weak ligation at equatorial sites of DyIII in 1 and 2 ensure 1@Y and 2 possess SMM behavior, although the coordination geometry of DyIII (TDD-8) in 1 and 2 severely deviates from the ideal polyhedron and its axial symmetry is low.

Application of EHD combination and triangular blades to enhance the cooling rate of hot barriers

Cooling of fixed heat sources applying forced convection is one of the most significant issues in increasing heat transfer. In this study, the cooling method of cylindrical ribs was investigated under the influence of forced convection as well as electric field induction. Cylindrical barriers are mounted at the bottom of the channel with an optimal zigzag arrangement. Heat transfer methods are studied with a compound of EHD and turbulence generators in the ranges of Re = 500 to Re = 3500. In the active method, Corona wind is used to disturb mainstream patterns and direct them towards ribbons. In the passive method, by installing turbulence generators on the areas of interest between cylindrical barriers. Also, by crossing the forced mainstream through the channel, a pressure gradient emerged that raises the speed and torsion of the flow followed by an increased heat transfer rate. The results reveal that the secondary flow resulted from corona wind is more effective in lower Reynolds numbers. In the passive method, the rise of Reynolds number improved the effects of this method.

Mechanical properties of intrinsic and defective hybrid polyaniline (C3N)-BC3 nanosheets in the armchair and zigzag configurations: a molecular dynamics study

In this paper, by the means of molecular dynamics simulations, the mechanical properties of defective hybrid C3N-BC3 in both armchair and zigzag arrangements have been studied. For the purpose of using this hybrid in nanotransistors and nonodiodes due to its special electrical properties, the mechanical properties of this nanosheet have been studied under various conditions. First, the failure stress, failure strain, and Young’s modulus of defect-free hybrid C3N-BC3 have been investigated. The findings denoted that the hybrid C3N-BC3 has moderate mechanical properties compared to pure C3N and pure BC3 in both armchair and zigzag structures. Then, the effect of circular and square defects has been investigated and it showed that sheets with circular defects have slightly better mechanical properties. Then, the effect of size, density, and positions of circular defects in both armchair and zigzag configurations have been analyzed and discussed. The findings showed that defects have a weakening impact on mechanical properties including failure stress and strain and Young’s modulus. However, the effect of these flaws on Young’s modulus is less than their effect on failure stress and strain. For instance, by increasing the density of circular holes in the C3N part of the hybrid in the armchair arrangement, the failure stress decreased nearly to about 50% whereas Young’s modulus diminished 15%.

1H NMR in a quasi-one-dimensional zig-zag spin chain of hambergite, Be2BO3(OH)

One-dimensional spin chains are important testbeds for the investigation of quantum many-body systems. Here, we introduce a new quasi-one-dimensional chain of spin-1/2 1H nuclei in hambergite (Be2BO3(OH)) crystal. The distinctive feature of hambergite is the zig-zag arrangement of the spins in the chains compared to the systems reported earlier. A single crystal of hambergite was investigated experimentally using 1H nuclear magnetic resonance at different orientations in the external magnetic field. The experimental spectra were compared with the Van Vleck’s second moments calculated from the structural data. For the orientation of the chain along the external magnetic field the resonance resembles that of the linear spin chains and the calculated contributions to the second moment from spins within one chain of hambergite amount to 96%. For other orientations the spectra demonstrate features specific to the zig-zag chain. Our results show that 1H nuclei in hambergite crystals could serve a good model of a well-isolated zig-zag spin chain.

A numerical study of the effect of channel spacers on the performance of cross-flow forward osmosis membrane modules

In this paper, we perform two-dimensional simulations of cross-flow forward osmosis (FO) membrane modules in the presence of draw and feed channel spacers. For this purpose, the equations corresponding to the conservation of mass, momentum, and convection-diffusion for the mass fraction of solute are solved using a commercial finite volume flow solver. We consider six configurations of channel spacers being constructed by the symmetric and asymmetric placement of cavity, submerged, and zigzag arrangements. We will study the effect of the spacers’ geometrical parameters such as diameter and relative distance in these configurations as well as the solute resistivity of the porous support layer on the performance of the FO membrane modules in terms of water flux, external concentration polarization (ECP) factors, and pressure drop per unit length of the membrane. Our results reveal that increasing the solute resistivity of the porous support layer has an adverse effect on the water flux, whereas the impact on the ECP factors is positive. In addition, it turns out that the submerged configurations, where the spacer filaments are not in direct contact with the membrane surface, produce the highest water flux through the membrane; however, they have an adverse effect on the pressure drop along the membrane surface.

The manufacturing of a surface anchor structure for the electroless plating of a three-dimensional antenna integrated with a mobile device case

This study proposes a method to improve the manufacturing process of a surface anchor structure for the injection molding along with bonding properties of the plating layer for antennas, which can be applied to the Laser Direct Plating (LDP) process for the production of a three-dimensional antenna integrated with a mobile device case. By adjusting parameters such as the output of the laser processing, scanning speed, and pulse recurrence frequency, a micro anchor structure was developed on the surface of the injection mold. The measurement of the surface roughness using a 3D surface profiler showed that the roughness improved by approximately 3.6 times, from 0.96 to 3.24 µm. In addition, the zigzag arrangement of the micro anchor structure was improved by 1.2 times compared to the even arrangement. Furthermore, if the micro anchor structure contained a wall after laser processing, the bonding strength of the plating solution was 69%; with no wall, it was 94% or higher. Thus, the existence of walls resulted in a difference of 1.4 times in the bonding strength. The laser processing improved the bonding strength of the plating solution on the micro anchor structure by approximately 19 times.

Online acoustic emission source localization in concrete structures using iterative and evolutionary algorithms

This study is motivated by the need to develop an efficient online structural health monitoring (SHM) framework to accurately localize damage induced acoustic emission (AE) sources in concrete structures. Experimental studies are carried out in concrete slabs considering pencil lead break (PLB) as artificial damage source to initialize acoustic emission (AE) waves. A simplified yet robust Iterative Planar Source (IPS) localization algorithm based on arrival time (ToA) is proposed first to identify arbitrarily selected several damage source locations for (1) rectangular (2)circular, and (3) zig-zag distributed AE sensor network arrangements. The results of the proposed localization algorithm are then compared with those obtained from an evolutionary particle-swarm optimization (PSO) algorithm for each sensor network arrangement to assess the performance of the AE source monitoring strategy. It is found that the zig-zag arrangement of the distributed AE sensors is the most efficient sensor network arrangement for damage source localization. The obtained results clearly represent the accuracy and robustness of the proposed online monitoring framework for localizing damage induced acoustic emission sources in concrete structures without extensive manual intervention.

Wetting behavior of textured silicon surfaces- an experimental study

The behavior of a liquid on a solid surface has shown great interest in a variety of applications related to surfaces and its interfaces. In this paper, the wetting behavior of DI water on micropatterned silicon surfaces fabricated through photolithography and deep reactive ion etching (DRIE) is investigated. Micro pillars of both solid and hollow geometries at a varying pitch and its arrangement in an array has been examined with static contact angle measurement. However, the results concluded that the arrangement of pillars in an array plays an important role as hollow geometries in the case of chain type arrangement provide both hydrophilic and hydrophobic surface properties, while the same hollow geometries in case of zig-zag orientation experiences only hydrophobicity at a varying pitch. Decreased WCA with increased pitch has been observed in the case of a zig-zag arrangement, due to the effect of capillary and gravitation forces. Also the existence of air pockets at sharp corner in the case of hollow square assists in providing maximum contact angle (WCA = 144°) as compared to hollow circle and solid geometries; thus a non-sticky behavior would be possible between the droplet and the patterned surface, due to less adhesion force.

Experimental investigation on bed shear stress distribution in the roughened compound channel

The roughness in the floodplains in a compound canal and its impact on hydraulic parameters such as the shear stress and their estimation are one of the problems that have attracted the attention of engineers. In this research, the aim is to investigate the effect of artificial on the floodplain of the compound channel on hydraulic parameters. In experiments, slope of channel bed was 0.0015 and three different discharges have been used. The four types of rigid roughness were used to investigate the effect of these parameters. These roughness elements were arranged with zigzag state with two distances of 4 k and 8 k (k is the height of roughness) in the floodplain. A Preston tube with an external diameter of 3 mm that equipped with dynamic pressure sensors was used to compute the shear stress. The Patel calibration curve was used in order to convert the difference between the static and dynamic pressure measured by the Preston tube to the shear stress values. The results showed that for the zigzag arrangement with the density of 4 k, the shear stress is reduced due to the high roughness density and the greater roughened area. In a rough bed, the shear stress in floodplain was significantly higher than smooth bed, and the stress distribution is such that it has descending trend from the main channel toward the wall of the floodplain. The shear stress increase for roughness with a spacing of 8 k is 22–36% higher than the similar hydraulic condition in a smooth bed and the shear stress for condition with the presence of a cylinder with D = 3 cm and roughness spacing of 8 k was 14–18% higher than the shear stress of bed without a cylinder and the same roughness density. The shear stress for condition of the presence of a cylinder with D = 6 cm and roughness spacing of 4 k is 24–30% more than the roughened plain with distances of 4 k.

Structural analysis of intramolecular 1,5-type O⋯O and S⋯O interactions in diethyl 2-oxo and diethyl 2-thioxo-1H benzo[d]imidazole-1,3(2H)-dicarboxylate: Experimental and theoretical study

Four compounds derived from 2-hydroxy and 2-mercaptobenzimidazole were synthesized and characterized by FT-IR spectroscopy, nuclear magnetic resonance and elemental analysis. Two of the resulting compounds –diethyl 2-oxo-1H benzo[d]imidazole-1,3(2H)-dicarboxylate and diethyl 2-thioxo-1H benzo[d]imidazole-1,3(2H)-dicarboxylate– were crystallized and analyzed by X-ray diffraction. The former presented intermolecular interactions of bidentate hydrogen-bonds and the formation of R22(10) rings via C–H⋯OC, resulting in a stacking arrangement while the latter had a zig-zag arrangement due to the intermolecular aromatic interaction C–H⋯OC. A computational conformational study was made to support and explain the resulting structures stabilities. Furthermore, a QTAIM analysis was performed to study the nature of the intramolecular 1,5-type O⋯O and S⋯O interactions.

A Unified Mechanism on the Formation of Acenes, Helicenes, and Phenacenes in the Gas Phase.

A unified low-temperature reaction mechanism on the formation of acenes, phenacenes, and helicenes-polycyclic aromatic hydrocarbons (PAHs) that are distinct via the linear, zigzag, and ortho-condensed arrangements of fused benzene rings-is revealed. This mechanism is mediated through a barrierless, vinylacetylene mediated gas-phase chemistry utilizing tetracene, [4]phenacene, and [4]helicene as benchmarks contesting established ideas that molecular mass growth processes to PAHs transpire at elevated temperatures. This mechanism opens up an isomer-selective route to aromatic structures involving submerged reaction barriers, resonantly stabilized free-radical intermediates, and systematic ring annulation potentially yielding molecular wires along with racemic mixtures of helicenes in deep space. Connecting helicene templates to the Origins of Life ultimately changes our hypothesis on interstellar carbon chemistry.

Vortex shedding patterns in flow past a streamwise oscillating square cylinder at low Reynolds number using dynamic meshing

We present a two-dimensional numerical study for uniform flow past a streamwise oscillating square cylinder at a Reynolds number of 200. To overcome the limitations with an oscillating inlet flow as used in earlier studies, a dynamic meshing feature is used to oscillate the cylinder. A parametric study is carried out by varying amplitude and frequency of cylinder oscillation. Two symmetric modes, named here as S-II-I and S-IV-D, have been found. In S-II-I mode, a pair of vortices are shed symmetrically on each side of the cylinder in one cycle (S-II mode), and in S-IV-D mode, two pairs of vortices of opposite sense are shed on each side of the cylinder. A vortex flapping mode has also been obtained for low to moderate amplitude and frequency ratios. A new mode of vortex shedding termed the “vortex dipole” mode is found and involves the alternate arrangement of vortex pairs unlike the zigzag arrangement of single vortices in a Kármán vortex street. As in most nonlinear oscillators, vortex shedding becomes chaotic when forced sufficiently strongly and is usually associated with nonlinear interactions between competing frequencies. Many modes observed in the current study become chaotic when the peak cylinder velocity becomes comparable with the inlet velocity. The 0-1 test for chaos is applied to the time series of lift coefficient to show that the signals are truly chaotic. We also observe chaos due to mode competition when shedding transitions from an antisymmetric to symmetric modes.

Synthesis and characterisation of new Ni2Mn, Ni2Mn2 and Mn8 clusters by the use of 2-pyridyl oximes

The initial employment of methyl 2-pyridyl ketoxime, (py)C(Me)NOH, in mixed metal Ni/Mn cluster chemistry, provided access to complexes [NiII2MnIII{(py)C(Me)NO}6](ClO4) (1) and [NiII2MnIII2{(py)C(Me)NO}6(OMe)2(MeOH)2](ClO4)2 (2) that display a linear and a zig-zag metal arrangement, respectively. 1 and 2 are synthesized by reacting Ni(ClO4)2·6H2O, (py)C(Me)NOH, Mn(ClO4)2·6H2O and NaOMe in different molar ratios (2:6:1:6, 1; 1:3:1:3, 2) in MeOH, and they are the first examples of 3d–3d′ mixed-metal clusters bearing (py)C(Me)NOH. The employment of phenyl 2-pyridyl ketoxime, (py)C(ph)NOH, instead of (py)C(Me)NOH, provided access to the octanuclear homometallic compound [MnII4MnIII4O4(NO3)2{(py)C(ph)NO}8(HCO2)2(MeOH)2] (3) that possesses a double-butterfly {MnII4MnIII4(μ4-O)2(μ3-O)2}12+ core. 3 joins the small family of Mn/(py)C(ph)NO− clusters. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on 1 and 2 and revealed the presence of antiferromagnetic exchange interactions between the metal ions (JMn–Ni = −6.34 ± 0.14 cm−1 in 1;JMn–Ni = −4.57 ± 0.08 cm−1, JMn–Mn = −12.72 ± 0.12 in 2) and a diamagnetic ground state for both compounds.

Magnetostructural Studies on Zigzag One-Dimensional Coordination Polymers Formed by Tetraamidatodiruthenium(II,III) Paddlewheel Units Bridged by SCN Ligands

We report herein on three zigzag one-dimensional coordination polymers of {[Ru2(μ-NHOCR)4](μ-SCN)}n (R = o-Me-C6H4 (2), m-Me-C6H4 (3), p-Me-C6H4 (4)) formula. These new compounds have been obtained by reaction of the corresponding [Ru2(μ-NHOR)4(THF)2](BF4) complex with (NBu4)(SCN) under different synthetic conditions. The crystal structure of [Ru2(μ-NHOCC6H4-o-Me)4(THF)2](BF4) (1), 2 and 3 are presented. A cis-(2,2) arrangement of the amidate ligands of the [Ru2(μ-NHOCR)4]+ units is observed in all cases. Interestingly, the structures of 2 and 3 show linkage isomerism in alternated tetraamidatodiruthenium units whose axial positions are occupied by the same type of donor atom of the SCN ligands. This results in zigzag chains with a Ru-S-C angle of 98.97° and Ru-N-C angle of 169.36° in the case of 2 and 97.99° and 159.26°, respectively, in the case of 3. The magnetic data obtained for 2–4 are indicative of a σ2π4δ2(π*δ*)3 ground state (S = 3/2) and a large zero-field splitting (ZFS) in all cases (D = 54.57, 62.72 and 43.00 cm−1 for 2–4, respectively). Similar small antiferromagnetic interactions between diruthenium units (zJ = −0.93, −0.79 and −1.11 cm−1 for 2–4, respectively) are estimated for all the polymers, suggesting an analogous zigzag arrangement of the chains for 4.

Investigating the Impact of Ultrasonic Irradiation Power, Concentrations of Reactant, and Reaction Period on Morphology of Novel Nano Hg(II) Metal–Organic Coordination Polymer

In the present work, using sonochemical method, novel mercury (II) metal–organic supramolecule with nano-rods shape, [Hg(1,10-phen)Cl2]n (1) (1,10-then = 1,10-phenanthroline) was prepared. The impact of the synthesis elements including duration, irradiation power, and concentrations was investigated and enhanced. Nano rods and nano flowers morphologies were obtained by applying diverse sonication time, power and concentration. The samples were categorized via IR spectroscopy, scanning electron microscopy, single crystal X-ray analysis, elemental analysis, X-ray photoelectron spectroscopy and X-ray powder diffraction. Based on the X-ray structure analysis, it was observed that two nitrogen atoms of the “1,10-phen” ligand and four chloride bridging atoms with symmetrical octahedral geometry and a HgN2Cl4 donor set coordinate the Hg(II) atom. A one-dimensional zig-zag polymer is created by the crystal forms. The nearby chains attached to π–π of nearby aromatic circles of “1,10-phen” and other weak interactions. Hence, as a result of the weak interactions, it is possible for the 1D zig-zag arrangement to create a three dimensional metal–organic coordination polymer. Through thermolyzing the compound 1 with oleic acid as a surfactant at the temperature of 180 °C, HgO nanoparticles were obtained. Using SEM, the as-synthesized HgO nanoparticles were further tested in terms of the morphology and size.

Unusual packing of soft-shelled nanocubes.

Space-filling generally governs hard particle packing and the resulting phases and interparticle orientations. Contrastingly, hard-shaped nanoparticles with grafted soft-ligands pack differently since the energetically interacting soft-shell is amenable to nanoscale sculpturing. While the interplay between the shape and soft-shell can lead to unforeseen packing effects, little is known about the underlying physics. Here, using electron microscopy and small-angle x-ray scattering, we demonstrate that nanoscale cubes with soft, grafted DNA shells exhibit remarkable packing, distinguished by orientational symmetry breaking of cubes relative to the unit cell vectors. This zigzag arrangement occurs in flat body-centered tetragonal and body-centered cubic phases. We ascribe this unique arrangement to the interplay between shape and a spatially anisotropic shell resulting from preferential grafting of ligands to regions of high curvature. These observations reveal the decisive role played by shell-modulated anisotropy in nanoscale packing and suggest a plethora of new spatial organizations for molecularly decorated shaped nanoparticles.