Flat Square Research Articles

Estimation of mass and moisture content of flat square lumber in a stack during air-drying process by the vibration method with additional mass

A vibration test to measure the mass of a specimen without weighing it using the difference between the resonance frequency with an additional mass and that without it (vibration method with additional mass, VAM) was applied to Japanese cedar flat square lumber with dimensions of 210 mm × 135 mm × 3000 mm both with and without a pith in the process of air-drying. The longitudinal and bending vibration tests were performed on the specimens with and without an additional mass. The accuracy of VAM that was expressed by the estimated mass by VAM to the measured mass (MVAM/M0) was sufficiently high throughout the air-drying process. The accuracy of VAM for the longitudinal vibration was higher than that for the bending vibration. The moisture content based on the estimated mass by VAM was in the expected range.

A study using physical sphere-in-contact models to investigate the structure of close-packed nanoparticles supported on flat hexagonal, square and trigonal lattices

The tailored design of nanoparticles becomes more important with the advancement of heterogeneous catalysis and materials science. The formation of nanoparticles in catalysts with a specific geometry of the active site becomes necessary to improve activity and selectivity in catalysis. Here we have used physical sphere-in-contact models of various nanoparticles with hexagonal, square and trigonal geometries on flat close-packed surfaces to understand how the distribution of (100) and (111) sites changes as a function of nanoparticle (NP) size in a simplified model of nanoparticle supported metals. The results from this approach clearly show that in 2-layer NPs that have a hexagonal base have 2–3 times more (100) sites than the square and trigonal base NPs as a function of the number of atoms in the NP. In 3D isotropic NPs, this phenomenon is even more pronounced than the 2-layer NPs. We derive equations that estimate the number of (100), (111), the number of atoms and the aspect ratio as a function of n. These equations are important in tailoring the properties of NPs supported on close-packed metal surfaces, which may find applications in materials science, nanotechnology and catalysis.

Absolute Quantification of Glutathione Using Top-Hat Optics for IR-MALDESI Mass Spectrometry Imaging.

Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) uses an infrared laser to desorb neutral biomolecules with postionization via ESI at atmospheric pressure. The Gaussian profile of the laser with conventional optics results in the heating of adjacent nonablated tissue due to the energy profile being circular. A diffractive optical element (DOE) was incorporated into the optical train to correct for this disadvantage. The DOE produces a top-hat beam profile and square ablation spots, which have uniform energy distributions. Although beneficial to mass spectrometry imaging (MSI), it is unknown how the DOE affects the ability to perform quantitative MSI (qMSI). In this work, we evaluate the performance of the DOE optical train against our conventional optics to define the potential advantages of the top-hat beam profile. Absolute quantification of glutathione (GSH) was achieved by normalizing the analyte of interest to homoglutathione (hGSH), spotting a dilution series of stable isotope labeled glutathione (SIL-GSH), and analyzing by IR-MALDESI MSI with either the conventional optical train or with the DOE incorporated. Statistical comparison indicates that there was no significant difference between the quantification of GSH by the two optical trains as evidenced by similar calibration curves. Results support that both optical trains can be used for qMSI without a change in the ability to carry out absolute quantification but providing the benefits of the top-hat optical train (i.e., flat energy profile and square ablation spots)-for future qMSI studies.

Effects of measured and simulated diffraction from a plate on sound source localization.

In daily life, natural or man-made structures influence sound propagation, causing reflections and diffraction with potential effects on auditory spatial perception. While the effect of isolated reflections on binaural localization has been investigated, consequences of edge diffraction on spatial perception have received less attention. Here, effects of edge diffraction on the horizontal localization of a sound source were assessed when a flat square plate occludes the direct sound or produces a reflection in an otherwise anechoic environment. Binaural recordings were obtained with an artificial head for discrete sound source positions along two horizontal trajectories in the vicinity of the plate, including conditions near the incident and reflection shadow boundary. In a listening test, the apparent source position was matched for conditions with and without the plate, resulting in azimuth offsets between the apparent and physical source of up to 12°. The perceived direction of occluded frontal sound sources was laterally shifted to the visible region near the edge of the plate. Geometrical-acoustics-based simulations with different methods to binaurally render diffracted sound paths were technically and perceptually compared to the measurements. The observed localization offset was reproduced with the acoustic simulations when diffraction was rendered considering the individual ear positions.

Investigation of aerodynamic effects of rotation on 6-DOF motion of flat square plate based on free flight experiments

Plate-like debris is common windborne debris in windstorms. Although the 3-degree-of-freedom (3-DOF) motion (two translational DOFs and one rotational DOF) of flat plates has been widely investigated in previous studies, the 6-DOF motion is more likely to occur in real storms. We investigate the 6-DOF motion by performing free flight experiments of a square plate with different initial orientations under uniforms flow in a wind tunnel. Two cameras are used to record the flight motion of the plate. Then the recordings are processed in an image analysis software to estimate the kinematics of the plate. We first investigate the characteristics of the rotational motion. According to the rotational characteristics, the plate trajectories are categorized into four flight patterns: flutter, tumbling, transition, and quasi-translation. Then we explore the rotational effects on the aerodynamics. We propose a hypothesis that the magnitude and direction of the rotational forces depend on the angular velocity and the relative wind velocity. We also propose a hypothesis that the rotational moment has negligible influences on the direction of the instantaneous moment. These hypotheses are supported by the experimental results. These verified hypotheses may be helpful for modelling the aerodynamics of the 6-DOF motion of flat plates.

The effect of whole-body vibration therapy on mechanical nociceptive thresholds and postural stability in horses with thoracolumbar pain

ObjectivesTo determine the effects of WBV on thoracolumbar pain, multifidus muscle CSA, and postural stability in horses with thoracolumbar pain AnimalsTen horses with thoracolumbar pain ProceduresHorses received WBV for 30 minutes once daily, 5 days per week, for 30 days. Mechanical nociceptive thresholds (MNTs) at T13, T18, L3, L6, S2 were assessed on days 0, 1, 14, and 30. Ultrasound of the multifidus muscle cross-section area (CSA) and postural sway (2 conditions: flat square stance and standing on proprioceptive balance pads) were assessed on days 0 and 30. ResultsMNTs were significantly lower than baseline on day 1 (P<0.001) and day 14 (P=0.004). MNTs were significantly higher than baseline on day 30 (P<0.001). Mediolateral accelerations were significantly lower on day 30 compared to day 0 (P< 0.001). Multifidus muscle cross-sectional area was significantly increased on day 30 compared to day 0 (P = 0.0005). Clinical relevanceWBV may exacerbate pain in horses with thoracolumbar pain when used short-term (<14 days). Long-term use (4 weeks) is needed to improve thoracolumbar pain. Four weeks of once daily WBV is sufficient to improve postural stability and increase multifidus muscle CSA.

The Relationship Of The Talking Stick Learning Method With The Students Learning Activity

This study aims to determine the relationship between the talking stick learning method and the active learning of students in grade IV SDN Tejo 1 Mojoagung. This research is applied to class IV in mathematics subjects, especially the subject matter of building flat squares, rectangles and triangles. This study uses a type of quantitative research on correlation or looking for the level of relationship between two variables, the subject used by the researcher is the entire sample in grade IV students. The sample used was 24 students, consisting of 11 men and 13 women. The data collection method is carried out using questionnaires for student responses and the relationship between the Talking Stick method and student learning activity, observation to find out student learning activity and documentation. The data collection instrument uses observation and questionnaire, after collecting data on the sample. The next step is to analyze the data obtained using descriptive statistics and inferential statistics. after the data is said to be valid the results are calculated using the help of SPSS for windows 22.0. hypothesis test using the two-mean difference test with r table. This test is affected by two variances. The results of the study were students' responses to the application of the Talking Stick learning method with the active learning of students in grade IV SDN 1 Mojoagung, namely in the very good category where there were 24 students, range 14, minimum score 86, maximum value 100, average or mean 98.33, sum 2360, standard deviation 4,280. observations between researchers and students about student learning activity before the method is applied with after there is a difference students look more active and comfortable with the talking stick learning method. The result of the correlation between variables X and Y with categories is very strong where the rxy value is 0.998 obtained from the questionnaire of the relationship between the two variables.

Empirical Shape-Based Estimation of Settling Microplastic Particles Drag Coefficient

Microplastics (MP) are found in nature in various forms. The transport and settling process of MP particles in water streams is highly influenced by particle size and shape. In order to investigate the impact of particle shape, an experimental analysis of settling behavior of flat square particles and 3D cubic particles in flowing water was conducted. The analysis is based on tracking the settling trajectories of particles of various size and using this information for calculating the drag coefficient cd in relation to the Reynolds number Re in the range of 80 to 280 for cubes and 50 to 110 for flat particles. The results were correlated with two shape parameters, sphericity ϕ and a newly proposed shape descriptor dimensionality δ. The final output is a model for particle shape-based cd estimation, mainly serving as an illustration of the potential of the proposed methodology.

Stress corrosion cracking failure of X80 carbon steel U-bend caused by Desulfovibrio vulgaris biocorrosion

Sulfate reducing bacteria (SRB) are widely present in oil and gas industry, causing pitting corrosion on pipeline steel. Stress corrosion cracking (SCC) often occurs in the presence of mechanical stress before pitting perforation failure, leading to economic losses and even catastrophic accidents. In this study, stress distribution simulation using the finite element method (FEM), corrosion analysis techniques and electrochemical corrosion measurements were employed to investigate the SCC mechanism of X80 pipeline steel caused by Desulfovibrio vulgaris, which is a common SRB strain used in microbiologically influenced corrosion (MIC) studies. It was found that D. vulgaris MIC caused sharp microcracks on an X80 U-bend coupon after only 2 weeks of immersion at 37 °C in the deoxygenated ATCC 1249 culture medium inoculated with D. vulgaris. The X80 U-bend coupon's weight loss-based uniform corrosion rate for the 12 cm2 surface was 60% of that for the unstressed flat square coupon (2.3 mg cm−2 vs. 3.8 mg cm−2). This was likely because the square coupon had wide MIC pits, providing a larger effective surface area for more sessile cells (4.2×108 cells cm−2 on square coupon vs. 2.4×108 cells cm−2 on U-bend coupon) to attach and harvest more electrons. An SCC failure occurred on an X80 U-bend pre-cracked at the outer bottom after a 6-week immersion in the D. vulgaris broth. Apart from MIC damage, this could also be because D. vulgaris metabolism increased the availability hydrogen atoms on the steel surface, and promoted the diffusion of hydrogen atoms into the metal lattice, thus increasing the brittleness of the steel.

X80 U-bend stress corrosion cracking (SCC) crack tip dissolution by fast corroding Desulfovibrio ferrophilus IS5 biofilm

Stress corrosion cracking (SCC) is a serious problem threatening structural integrity and safety. Metal corrosion pits can develop into more harmful cracks under mechanical stress. It is known in abiotic corrosion that fast corrosion does not necessarily cause more severe SCC. This is because fast corrosion can prevent or dissolve crack tips and convert them into less harmful pits if the uniform corrosion rate is fast enough. This work experimentally proved the hypothesis that the same phenomenon occurs in biotic corrosion. It was found that a highly corrosive SRB (sulfate reducing bacterium) strain, namely Desulfovibrio ferrophilus (strain IS5), caused fast uniform corrosion and dull pits, but no SCC cracks against X80 carbon steel U-bend coupons (stressed). In comparison, Desulfovibrio vulgaris, a far less corrosive SRB strain caused less corrosion, but generated sharp pits and SCC cracks in a 3-month lab test. This work also revealed that the X80 U-bend had a 44% higher sessile cell count and 34% higher weight loss after a 14-d D. ferrophilus incubation in deoxygenated enriched artificial seawater culture medium at 28 °C when compared with the (flat) square coupons (no stress). This weight loss trend was corroborated by transient electrochemical measurements.

Settlement patern of Lusatian culture in Podlasie (NE Poland) and man-environment interaction

Abstract Three sites from network of 27 structures of the Late Bronze/Early Iron Age Lusatian culture from NE Poland (Biebrza and Narew river basins) and man-environment interaction were study. These circular structures have a relatively uniform location, structure, type of construction and dimension. Two areas within these structure coud be distinguished: a protective area consisting of a system of ditches and embankments and a central area consisting of a flat central square with only some archaeological traces of economic activity. Determining the function of the structures is extremely difficult. Their structure does not indicate the defensive function of the objects. Their location near peat bogs may suggest their use as corals for grazing animals and intensive agricultural use of the environment are reflected in the valley bottom sediments. There are many indications that we are dealing here rather with a kind of stable socio-administrative-religious centre concentrating dispersed in the microregion population of the Lusatian culture.

Designing a Learning Trajectory of Area and Perimeter of Flat Shapes with Realistic Mathematics Education Approach for Fourth Grade Elementary School

This study was motivated by the lack of students' understanding of the concept of learning mathematics in elementary schools in measuring the area and perimeter of flat shapes. Therefore, the researchers designed and developed a learning trajectory of area and perimeter of flat shapes, square and rectangle, with Realistic Mathematics Education approach. The study used design research as methodological approach consisting of three phases, the preparatory phase, the experimental phase, and the retrospective analysis phase. The learning trajectory was tested with 14 students, 4 students for one to one and 10 students for experimental process. The data were gathered from interviews with several students, observations from videos during the learning process, and analysis of students' worksheets. The findings of the study showed that the learning trajectory of area and perimeter of flat shapes with Realistic Mathematics Education approach triggered students to develop their mathematical reasoning on the concept of area and perimeter of flat shape, square and rectangle.

Lattice Green/Neumann function for the 2D Laplacian operator defined on square lattice on cylinders, tori and other geometries with some applications

The lattice Green functions for the discrete planar Laplacian defined on regular square lattice wrapped around cylinders and tori are rigorously defined and obtained in an exact analytic form. The method of images well-known in potential theory is implemented to derive for many other geometries with free boundaries (semi-infinite or finite cylinders and strips, rectangle) the related exact lattice Green-Neumann functions needed to readily solve discrete Neumann problems or, via a Neumann-to-Dirichlet mapping, discrete Dirichlet problems for these flat square lattices. Some applications are thus proposed as explicit expressions of two-point resistances for related resistor networks, and some probability-based characteristics regarding the associated Pòlya’s random walks.

Epitaxial GaSb films directly grown on on-axis Si(001) with low defect density by MBE

In recent years, GaSb-on-Si direct heteroepitaxy has been highly desirable to extend the operating wavelength range into mid-infrared and high-mobility applications, such as free-space communications, gas sensing, and hyperspectral imaging. High-quality GaSb films on Si remain challenging due to the high density of defects generated during the growth. For this purpose, epitaxial GaSb films were grown by molecular beam epitaxy on on-axis Si(001). Due to the large lattice mismatch (12.2%) between GaSb and Si, here, we proposed a radical design and growth strategy with the primary objective of achieving the annihilation of antiphase boundaries (APBs) and the reduction of threading dislocation density (TDD). Benefitting from a V-grooved Si hollow structure, we demonstrated the growth of emerging-APB-free GaSb film on Si(001) with low mosaicity. Moreover, by introducing InGaSb/GaSb dislocation filtering layers, the atomically flat surface root mean square roughness is improved to 0.34 (on Si) and 0.14 nm (on GaAs/Si). Moreover, the corresponding TDD can be reduced to 3.5 × 107 and 2 × 107 cm−2, respectively, one order of magnitude lower than the minimum value found in the literature. These reported results are a powerful lever to improve the overall quality of epitaxial Si-based antimonide, which is of high interest for various devices and critical applications, such as laser diodes, photo-detectors, and solar cells.

Evidence of Formation of 1–10 nm Diameter Ice Nanotubes in Double-Walled Carbon Nanotube Capillaries

Water exhibits rich phase behaviors in nanoscale confinement. Since the simulation evidence of the formation of single-walled ice nanotubes (INTs) in single-walled carbon nanotubes was confirmed experimentally, INTs have been recognized as a form of low-dimensional hydrogen-bonding network. However, the single-walled INTs reported in the literature all possess subnanometer diameters (<1 nm). Herein, based on systematic and large-scale molecular dynamics simulations, we demonstrate the spontaneous freezing transition of liquid water to single-walled INTs with diameters reaching ∼10 nm when confined to capillaries of double-walled carbon nanotubes (DW-CNTs). Three distinct classes of INTs are observed, namely, INTs with flat square walls (INTs-FSW), INTs with puckered rhombic walls (INTs-PRW), and INTs with bilayer hexagonal walls (INTs-BHW). Surprisingly, when water is confined in DW-CNT (3, 3)@(13, 13), an INT-FSW freezing temperature of 380 K can be reached, which is even higher than the boiling temperature of bulk water at atmospheric pressure. The freezing temperatures of INTs-FSW decrease as their caliber increases, approaching to the freezing temperature of two-dimensional flat square ice at the large-diameter limit. In contrast, the freezing temperature of INTs-PRW is insensitive to their diameter. Ab initio molecular dynamics simulations are performed to examine the stability of the INT-FSW and INT-PRW. The highly stable INTs with diameters beyond subnanometer scale can be exploited for potential applications in nanofluidic technologies and for mass transport as bioinspired nanochannels.

Experimental Study for Load-Settlement Behavior of Flat and Shell Footings on Sandy Silt Soil

Shell foundations are often used to raise the carrying capacity of a structure on weak soils. In cases where large superstructure loads must be transferred to poorer soils, shell foundations are more cost-effective than ordinary shallow foundations. Advances in the study and design of shell-type foundations have shown their superiority over traditional footings in poorer soils. The current study aims to investigate shell shape’s influence on ultimate load capacity. Seven footing types’ models were created along with an appropriate testing box. The soil needed for the study was from the region north of Mosul city, classified as silt with low plasticity (sandy silt) soil. A laboratory model experimentally determined the ultimate load capacities for inverted and upright conical, inverted and upright pyramid, and hemispherical shell foundations on silty soil. The achieved results were associated with those for conventional flat squares and circles. According to the findings, the “upright conical” shell footing has a load capacity of 12.7 kN, higher than the other foundations, and its efficiency was 51%. When comparing foundations, the “upright pyramidal” shell footing has better settling characteristics and a settlement factor of 0.017. As the shell factor decreases, the shell foundation begins to behave more like a flat foundation, which reduces the maximum load capacity of the shell foundation.

Displacement Calculation for Service Loads of Reinforced Concrete Beams and Slabs Using Physically Non-Linear Analysis

This paper aims to use non-linear physical analysis to calculate the displacement of beams and slabs in a cracked state. This study uses the commercial software SAP2000 to perform a numerical analysis using the finite element formulation, applying the multi-layer method. Initially, a parametric study was carried out to evaluate the vertical displacement for service loads of reinforced concrete beams and slabs using different spans, support conditions and geometry. In order to validate the finite element model, the study compared displacement values for linear analysis using Bares tables. Subsequently, simplified methods of displacement calculation in the long term are applied, using an abacus from Comité Euro-International du Béton (CEB). These values are then compared with the physically non-linear analysis in the long-term cracked state with SAP2000. Two structural codes were used in the numerical and analytical methods, Regulamento de Estruturas de Betão Armado e Pré-Esforçado (REBAP) and Eurocode 2 (EC2), to evaluate their differences in deformation control. Therefore, the main goal is to establish comparisons between the two methods of analysis in order to show that non-linear finite element modelling provides values that are lower than the analytical calculation, thus allowing greater economy in the design of structural reinforced concrete elements. In addition, it can be noted that EC2 has some inconsistencies in the design of simply supported slabs, requiring a greater thickness than a flat square slab and that indirect deformation for REBAP is underestimated for beams and, in some cases, for slabs.

극동 우데게족 우주관 분석

The purpose of this paper is to examine the originality and hybridity of these worldviews through the udege's conception of the shape of the universe and the structure of the universe as a three-tiered world based on the mythological data of the udege. In the concept of the udege, the shape of the universe was transformed into an inseparable unity in the mythological concept, and a flat square in the topographical and ecological concept. In the concept of the udege, the universe is a three-tiered structure of upper, middle, and lower worlds, and each world is further divided into multiple layers. Little is known about the structure of the upper ugu buga (ulije na, ba na) in the udege's conception, the emergence and completion of the relay bar in the concept of the udege is a process to establish the order of the universe, and it goes through the stages of existence of the original ocean→the appearance of the earth→the appearance of three suns and the death of two suns by a cultural hero. In the notion of the udege, the hegi uhe ba is structured as a first floor for kengma oyoni, a second floor for dokini oyoni, and a third floor for buniga. The cosmological view of the udege is located at the midpoint between the northern tungus tribe, the southern tungus tribe, and the paleoasiatic nivh.

Influence of Thermal Boundary Conditions and Number of Channels on the Performance of Heat Sinks with Rectangular Minichannels.

This paper aims to contribute to the analysis of a heat sink designed for the active cooling of small flat surfaces. The heat transfer device investigated here consists of a flat square substrate and a cover, separated by parallel channels with a rectangular cross-section. The cold air flowing in the channels is sucked from the environment, and the bottom of the substrate adheres closely to the hot surface of the device to be cooled. The thermal problem is tackled by considering two different conditions: the first one assuming one long side of the channel is heated and the three other sides are adiabatic (version 1L) and the second one assuming high conductivity of the walls (version 4), in both the H1 and H2 boundary conditions. Moreover, to investigate the effect of the number of channels on the performance of the heat sink, the number of channels is changed between 1 and 20. The results, presented in terms of the f Re product, Nusselt number, maximum surface temperature, and thermal resistance, reveal that both the thermal boundary conditions and the number of channels significantly affect the performance of the investigated heat transfer device.

An Efficient Unconditionally Stable Method for Dirichlet Partitions in Arbitrary Domains

A Dirichlet $k$-partition of a domain is a collection of $k$ pairwise disjoint open subsets such that the sum of their first Laplace--Dirichlet eigenvalues is minimal. In this paper, we propose a new relaxation of the problem by introducing auxiliary indicator functions of domains and develop a simple and efficient diffusion generated method to compute Dirichlet $k$-partitions for arbitrary domains. The method only alternates three steps: 1. convolution, 2. thresholding, and 3. projection. The method is simple, easy to implement, insensitive to initial guesses and can be effectively applied to arbitrary domains without any special discretization. At each iteration, the computational complexity is linear in the discretization of the computational domain. Moreover, we theoretically prove the energy decaying property of the method. Experiments are performed to show the accuracy of approximation, efficiency and unconditional stability of the algorithm. We apply the proposed algorithms on both 2- and 3-dimensional flat tori, triangle, square, pentagon, hexagon, disk, three-fold star, five-fold star, cube, ball, and tetrahedron domains to compute Dirichlet $k$-partitions for different $k$ to show the effectiveness of the proposed method. Compared to previous work with reported computational time, the proposed method achieves hundreds of times acceleration.