Parallelogram Shape Research Articles

Two-scale minimum compliance optimization of spatially graded plates with variable-height parallelogram microstructures

This work investigates the two-scale design optimization of graded plates with variable-height parallelogram microstructures based on asymptotic homogenization. First, updated unit cell problems, with an emphasis on rotational degrees of freedom, are proposed to evaluate shell-structured microstructures, so that a pointwise effective stiffness calculation can be efficiently conducted with shell elements, which is otherwise computationally prohibitive with solid elements. Then, a two-scale optimization framework seeking minimum compliance is established, where the design variables controlling both in-plane parallelogram shape and out-of-plane stiffener height are introduced to enlarge the design space. In addition, mapping functions are integrated into the optimization formulation and concurrently optimized, enabling the production of well-defined dehomogenized plates. Finally, numerical examples are presented to validate the effectiveness and correctness of the proposed method by comparing the deflections of the graded plates with those of the homogenized plates.

Crystallographic models of ribbons and ribbon-based J-aggregate nanotubes from the geometry of tube ends.

Self-assembly into tubular structures typically proceeds by helical winding of ribbon intermediates, however, only the central parts of the tubes, that retain no information on the ribbon geometry, have received attention so far. We propose the procedure of establishing the crystal structure of ribbons and ribbon-based tubes on the basis of crystallographic analysis of the tube-end geometry, where the terminal parts of the ribbons fold and form characteristic mono/bilayer polygonal shapes. The terminal parts of flattened J-aggregate nanotubes of trimethine cyanine dye were clearly resolved in electron microscopy and atomic force microscopy images, and the original parallelogram shape of ribbons was reconstructed and interpreted as a two-dimensional [1-10]/[010] facetted crystal with inclined molecular π-stacks parallel to the long ribbon side. The back-reconstructed molecular orientations in a tube wall tend to be close to the tube normal. A two-stage "nucleation and growth" type model of the ribbon to tube transition is proposed that takes into account the established ribbon mechanical asymmetry. The model includes closure of the single ribbon loop as a nucleation event and explains, mostly observed in experiments, nearly rectangular shapes of tubes by the transition kinetics. Due to its universal character, the suggested approach can be applied to any ribbon-based tubes, regardless of their chemical composition.

Ethnomathematics at TIFA Yapen as A Source for Learning Mathematics

This study's primary objective is to investigate and elucidate the principles and regulations of ethnomathematics prevalent in the Yapen Islands of Papua, Indonesia, for application in the context of mathematics education in schools. The research methodology involves qualitative research with an ethnographic approach. Data was collected through participant observation techniques and in-depth interviews, and the subsequent data analysis followed a sequence of ethnographic data analysis, domain analysis, and taxonomic analysis. The findings of this research indicate that precise measurements of the tifa's length and width significantly affect the sound (tone) produced when the tifa is struck. The design aspect involves the ability to elucidate the steps and sequence involved in crafting a tifa, ensuring clarity and comprehensibility in the explanation. Furthermore, the ability to explain extends beyond comprehending the manufacturing process to effectively communicating it to the general public. The geometric patterns observed on the tifa include circular shapes on the lid and base, a prism shape near the tifa cover, an isosceles trapezoid shape on the tifa handle, and a parallelogram shape on the tifa handle.

Miskonsepsi Siswa SMP Dalam Memahami Ciri-ciri Bangun Segi Empat

In this study, this qualitative research aimed to describe the misconceptions students of junior high school in understanding characteristics of quadrilateral plane figure. The misconceptions instrument were administered to three students in 8th grade of junior high school. Students understanding were analyzed by misconceptions test with CRI (Certainty of Response Index) method with interviews. The misconceptions in understanding the characteristics of quadrilateral plane figure (trapezoid and parallelogram) were the main result of this study. Students showed the same misconceptions in understanding the characteristics of quadrilateral plane figure. The first, Students assumed the diagonal trapezoid isosceles is the only a pairs of same length segment. The second, students only known the parallelogram and rectangle shape are in the regular quadrilateral shape (if the parallelogram and rectangle has different position or irregular shape then it is no called a quadrilateral). In particular, the results indicated that the students had misconceptions in understanding characteristics of quadrilateral plane figure. The misconception occurs because the ability of student understanding is low or incomplete. So, the teacher should gave more problem and images for understanding the characteristics of plane figure.

Line feature based self-calibration method for dual-axis scanning LiDAR system

LiDAR calibration is an essential step for acquiring accurate three-dimensional point-cloud. To enhance the convenience of calibration of dual-axis scanning LiDAR, a line feature based self-calibration method is proposed, which corrects point-cloud error by establishing observation model and estimating model parameters. The model parameters are estimated by minimizing the square error of line feature points, referring as straight edges extracted from point-cloud. The experimental results verify the effectiveness of the proposed method on improving point-cloud accuracy, the horizontal and vertical angular errors are reduced to 0.10° and 0.08° after calibration with reductions of 64% and 68%, respectively. The analysis on parameter correlation finds that, parameters can be divided into groups according to the introduced point-cloud error: dimension error, trapezoid and parallelogram shape distortion. A de-correlation strategy combining inter-group and stepwise intra-group de-correlation thus can be implemented, which can be applied for point-cloud quality enhancement in in-situ environmental perception scenes.

Effect of underactuated parallelogram shape-shifting for environmental adaptation movement of a three modular in-pipe robot.

This paper presents an in-pipe robot with three underactuated parallelogram crawler modules, which can automatically shift its body shape when encountering obstacles. The shape-shifting movement is achieved by only a single actuator through a simple differential mechanism by only combining a pair of spur gears. It can lead to downsizing, cost reduction, and simplification of control for adaptation to obstacles. The parallelogram shape does not change the total belt circumference length, thus, a new mechanism to maintain the belt tension is not necessary. Moreover, the proposed crawler can form the anterior-posterior symmetric parallelogram relative to the moving direction, which generates high adaptability in both forward and backward directions. However, whether the locomotion or shape-shifting is driven depends on the gear ratio of the differential mechanism because their movements are only switched mechanically. Therefore, to clarify the requirements of the gear ratio for the passive adaptation, two outputs of each crawler mechanism (torques of the flippers and front pulley) are quasi-statically analyzed, and how the environmental and design parameters influence the robot performance are verified by real experiments. From the experiments, although the robot could not adapt to the stepped pipe in vertical section, it successfully shifted its crawler's shape to parallelogram in horizontal section only with our simulated output ratio.

PENERAPAN MEKANISME COMPLIANT PADA MEKANISME GERAK GRIPPER

Innovation is a term for applying an idea that can form a new product or improve an existing product. The parallelogram shape is the most popular mechanism used in gripper because of its configuration that causes the tip to hold its orientation when closed and open. The drawback of this form is the large number of components needed and requires an assembly process in order to achieve the desired motion. A compliant mechanism can overcome this shortcoming because objects can be made simpler without the need for an assembly process. The advantages and disadvantages of the compliant gripper have been obtained from the design, test results, and comparisons. The design obtained with dimensions of P 186.27 X W 157.55 X H 10 mm uses a leaf-type flexure with varying thickness. The thicker it is the greater the force required to use the gripper. the results printed using a 3d printer also reflect the data that has been obtained regarding the style. The thinner the flexure, the more susceptible the tool is to external forces such as shocks. The comparisons made show that the advantages of the gripper are the minimum required components, no assembly process required, and a smaller mass compared to the reference mechanism. Disadvantages obtained are the decrease in the width of the opening distance and the orientation of the finger that changes according to changes in the angle at the fulcrum.

ТОПЫРАҚТЫҢ БЕТКІ ҚАБАТЫН ӨҢДЕУГЕ АРНАЛҒАН БЕЛСЕНДІ ЖЕТЕКГІ БАРАЙНАЛМАЛЫ ЖҰМЫСШЫ БӨЛІКПЕН ҚАРЫҚША ҚАЛЫПТАСУЫН ЗЕРТТЕУ

For the surface tillage, it is common to utilize machines and tools, and their tillage implements are set in motion through contact with the soil and by the tractor's PTO. The furrow produced by the rotating tillage implements is characterized by an uneven bottom that matches the furrow length and aligns with the direction of the movement of the machine-tractor aggregates. However, an analysis of research suggests that this scenario does not fully capture the process of furrow formation by the cutting blade of the concerned tillage implement powered by the tractor's PTO. For the reasons outlined above, determining the tillage implement parameters to achieve the desired quality of surface soil tillage is quite challenging. This article, therefore, delves into the process of furrow formation using the power driven tillage implement.The objective of this study is to develop a methodology for determining the parameters of the furrow formed by the power driven tillage implement’s cutting blade. Experiments were conducted in a soil box filled with sandy soil, considering approach angles ranging from 30 to 90° and kinematic parameters varying between 0.8 and 2.2. The findings reveal that the cutting blade of the rotating implement, designed in an elliptical fashion, generates a furrow that takes on a parallelogram shape when seen from above. At a small approach angle, the implement's cutting blade produces a short, narrow furrow that deviates from the implement's path and remains within the implement's working width.

A simple and cost effective method to detect adulteration in ghee with vegetable oils through microscopic examination of sterols

Plant sterols together called as phytosterols, and animal sterols mainly cholesterol differ from each other in their crystal shapes, apart from other differences in terms of chemical structure, melting points, etc. When viewed under the microscope, after their isolation from the samples in purified state, phytosterols crystals appear hexagonal in shape while those of cholesterol acquire parallelogram shape. But the mixture of phytosterols and cholesterol shows the crystal structure with re-entry angle (Swallow’s tail).On the basis of this characteristic crystal shape, detection of vegetable oils in milk fat up to a level of 15 percent could be confirmed with this simple cost effective method . However, this approach cannot be applied for the detection of body fats in milk fat because of the existence ofcommon sterol (cholesterol) in them

A Study Absorbance and Attenuation Coefficient and Impedance of Y-Type (Ba22 Co2-x Znx Fe12 O22) for Microwaves

In this research, a compound was prepared from hexagonal Ferrite with a chemical formula of (Ba2Co2-xZnxFe12O22) When the values of (x = 0.8,1,1.2), to study its absorbance ,attenuation coefficient, impedance to the microwaves within therange of X-band (8-12 GHz) and test it using Network Analyzer .The ceramic method (Solid state reaction) was used to to prepare three formulas of this compound:(Ba2Co1.2Zn0.8Fe12O22), (Ba2CoZnFe12O22), and (Ba2Co0.8Zn1.2Fe12O22). Nine samples were prepared with Parallelogram shape to fit the wave guide of the device to test them properly . The tests of the absorbance, the attenuation coefficient and the impedence were carried out for these samples. The results showed that the increase of sintering temperature lead to increase the attenuation coefficient and the absorbance. The best values were found at T= 1250C.It has been found that the compound (Ba2CoZnFe12O22) has the best value of the absorbance and the impedence.

Accuracy Bound for Positioning the 5R Planar Parallel Manipulator Subjected to Uncertainties in Dimensions and Actuations

This article is aimed to determine the accuracy bound for positioning the 5R planar parallel manipulator under the uncertainties in its dimensions and actuation. The accuracy bound is investigated numerically using the interval analysis and multi-dimensional bisection method (MDBM). These numerical methods can give multiple solutions within the workspace of the manipulator. Then, the exact solution is utilized for comparison with the numerical solutions. It is shown that the interval analysis via the interval Newton method gives the guaranteed bounds for positioning accuracy. Meanwhile, the MDBM and the exact solution coupling with the Monte Carlo simulation produce a scattered random value in a parallelogram shape inside the solution yielded by the interval Newton method. Overall, those three methods give nearly a good agreement in terms of that accuracy, but they are different at computation time.

Experimental study on seismic performance of steel slit damper under additional tensile load

Hysteretic steel dampers of the flexural/shear yield-type may resist unanticipated tensile load because of their installation pattern, boundary conditions, and scale difference with the frame. In this study, the effect of unexpected additional tensile loads on a flexural yield-type steel slit damper was experimentally analyzed. To this end, two experimental boundary conditions were applied as the experimental variables: 1) shear loading only, and 2) combined shear and tensile loading. Experimental results showed that the damper hysteresis under shear load has a typical parallelogram shape, whereas that under combined shear–tensile loading shows a butterfly-shaped curve. The effect of additional tension is proportional to the aspect ratio and maximum deformation angle of the damper. The plastic deformation capacity according to the cyclic hysteresis of the damper under additional tensile load was found to be similar to that of the damper under shear loading only, and the amount of plastic energy absorbed until failure was measured to be equal or higher. However, the dissipated energy of the damper under additional tensile load contains a substantial amount of unstable energy owing to out-of-plane deformation. According to the test results, the hysteresis of the damper under additional tension was found to be lower than the existing predicted curve for the evaluation of the plastic energy, and a design value was proposed for the predicted curve of the flexural yield-type steel slit damper under an additional tensile load.

Compression Behavior and Vibrational Properties of New Energetic Material LLM-105 Analyzed Using the Dispersion-Corrected Density Functional Theory.

The 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is a newly energetic material with an excellent performance and low sensitivity and has attracted considerable attention. On the basis of the dispersion-corrected density functional theory (DFT-D), the high-pressure responses of vibrational properties, in conjunction with structural properties, are used to understand its intermolecular interactions and anisotropic properties under hydrostatic and uniaxial compressions. At ambient and pressure conditions, the DFT-D scheme could reasonably describe the structural parameters of LLM-105. The hydrogen bond network, resembling a parallelogram shape, links two adjacent molecules and contributes to the structure stability under hydrostatic compression. The anisotropy of LLM-105 is pronounced, especially for Raman spectra under uniaxial compression. Specifically, the red-shifts of modes are obtained for [100] and [010] compressions, which are caused by the pressure-induced enhance of the strength of the hydrogen bonds. Importantly, coupling modes and discontinuous Raman shifts are observed along [010] and [001] compressions, which are related to the intramolecular vibrational redistribution and possible structural transformations under uniaxial compressions. Overall, the detailed knowledge of the high-pressure responses of LLM-105 is established from the atomistic level. Uniaxial compression responses provide useful insights for realistic shock conditions.

Hydromechanical Coupling Characteristics of the Fractured Sandstone under Cyclic Loading-Unloading

The mechanical and hydraulic properties of rock mass play a crucial role in underground engineering. To study the effect of hydraulic pressure, confining pressure, and axial cyclic loading-unloading on variation of the deformation and permeability in fractured rock mass, the coupling triaxial experiment of sandstone was conducted. The concept of permeability recovery rate (PRR) and permeability enhancement reduction rate (PERR) was proposed to characterize the change in permeability. The results show that the permeability of fractured sandstone quadratically varies with the change of hydraulic pressure and confining stress. In detail, the permeability decreases with the decrease of hydraulic pressure and increases with the decrease of confining stress, respectively. Compared with the single-fracture permeability, the double-fracture permeability is more sensitive to the change of hydraulic pressure. Furthermore, the permeability of fractured sandstone is more dependent on the hydraulic pressure than the confining stress. With the performance of axial cyclic loading-unloading, the permeability spirals down, and both the axial and radial residual strains quadratically evolve. Following the first axial cyclic loading-unloading, an obvious deformation memory phenomenon characterized by a parallelogram shape in axial stress-strain curves was observed for the sandstone. The cumulative PRR of 85%-95% was maintained in double-fracture sandstone. On the contrary, a fluctuation of cumulative PRR characterized by “V shape” was observed for single-fracture sandstone. The enhancement effect of axial cyclic loading on the permeability was characterized by the decrease of PERR for double-fracture sandstone and increase of PERR with a greater gradient for single-fracture sandstone.

A 0.07-mm2 162-mW DAC Achieving >65 dBc SFDR and < −70 dBc IM3 at 10 GS/s With Output Impedance Compensation and Concentric Parallelogram Routing

A digital-to-analog converter (DAC) with small-size non-cascoded current cells is proposed to achieve small area, low-power consumption, and high linearity over a wide bandwidth. An output impedance compensation (OIC) technique using a compensation resistor, implemented by a PMOS with code-dependent gate voltage control, is proposed to remedy the nonlinearity induced by the insufficient output impedance of the non-cascoded current cells. In addition, a proposed concentric parallelogram routing (CPR) technique, in which the subcells of each current cell are arranged such that they form a parallelogram shape with a common centroid, is used to reduce both the mismatch error and the routing-induced timing skew among the current cells. The DAC, implemented in a 28-nm CMOS process, achieves >65-dBc spurious-free dynamic range (SFDR) and < −70-dBc third-order intermodulation distortion (IM3) over the entire Nyquist bandwidth at 10 GS/s while consuming 162 mW from a single 1.1 V supply.

Solution-grown composite single crystals of poly(L-lactic acid)-b-polystyrene block copolymers and poly(L-lactic acid) homopolymers

In the present work, composite single crystals (CSCs) composed of poly (L-lactic acid) (PLLA) homopolymer and poly (L-lactic acid)-b-polystyrene (PLLA-b-PS) block copolymers (BCPs) were prepared by solution co-crystallization. The effects of crystallization temperature (Tc), mass ratio of BCP/homopolymer and PS block length on the morphology and growth habit of the CSCs were investigated. Particularly, parallelogram CSCs with four {110} crystal planes as edges tend to be formed at a low Tc and a small BCP/homopolymer mass ratio for the BCP with a short PS block. The parallelogram shape of the crystals indicates the growth rates along four {110} crystal planes are different in two directions. It is proposed that the folded surface free energy is reduced after incorporation of PLLA-b-PS BCP into the crystals, leading to accelerated growth and concave surface structure along the long side direction. The chain folding of the PLLA block in the CSCs was also discussed. It is found that, in order to match the chain folding of PLLA homopolymer, the PLLA block in the BCPs adopts more chain folds in the CSCs than that in the single crystals formed by neat BCPs.

On stability of linear dynamic systems with hysteresis feedback

The stability of linear dynamic systems with hysteresis in feedback is considered. While the absolute stability for memoryless nonlinearities (known as Lure’s problem) can be proved by the well-known circle criterion, the multivalued rate-independent hysteresis poses significant challenges for feedback systems, especially for proof of convergence to an equilibrium state correspondingly set. The dissipative behavior of clockwise input-output hysteresis is considered with two boundary cases of energy losses at reversal cycles. For upper boundary cases of maximal (parallelogram shape) hysteresis loop, an equivalent transformation of the closed-loop system is provided. This allows for the application of the circle criterion of absolute stability. Invariant sets as a consequence of hysteresis are discussed. Several numerical examples are demonstrated, including a feedback-controlled double-mass harmonic oscillator with hysteresis and one stable and one unstable poles configuration.

Taxonomy of the Lateral Strain Patterns at the Sphenobasilar Synchondrosis for Osteopathic Cranial Manipulative Medicine.

Lateral strain is a type of nonphysiologic cranial dysfunction that occurs at the sphenobasilar synchondrosis. In this dysfunction, the sphenoid and occiput rotate in the same directions along 2 vertical axes. There is currently no consensus on the nomenclature for this cranial dysfunction. In this article, the authors provide a standard nomenclature for lateral strains using the historical writings of pioneers in osteopathic medicine, including William Gardner Sutherland, DO, Anne L. Wales, DO, and Harold Magoun, DO. The authors establish the following consensus: (1) Lateral strains are named for the side to which the basisphenoid shifts; (2) The more prominent greater wing of the sphenoid is on the same side to which the basisphenoid shifts; (3) In vault and fronto-occipital holds, the holds form a parallelogram shape, with the index fingers pointing to the same side as the more prominent greater wing; and (4) The hand that is on the side of the prominent greater wing will shift anteriorly while the hand on the opposite side will shift posteriorly.

Ionic liquid mediated morphologically improved lanthanum oxide nanoparticles by Andrographis paniculata leaves extract and its biomedical applications

Greener synthesis of ionic liquid (IL) assisted lanthanum oxide (La2O3) nanoparticles (NPs) was followed using Andrographis paniculata leaves extract by hydrothermal method at low temperature. The IL assisted La2O3 (La2O3-IL) NPs were characterized by various properties such as structural, spectral, optical, morphological, and biological studies. Powder X-ray diffraction studies confirm that La2O3-IL NPs crystallize in the form of body-centered cubic structure and average crystalline size is shown ∼43 nm. FTIR and Laser Raman spectroscopy confirm the La–O, O–H and various functional groups. The La–O stretching vibration band attributes at 639 cm−1. The optical property of La2O3-IL NPs was characterized by UV-Vis and photoluminescence spectroscopy. The sharp and intense absorbance peak observed in the UV region at 288 nm can be assigned. In the PL spectrum, we observe two different emission bands like blue and green emission. The morphological and particle size determination were investigated by SEM with EDX spectra and TEM analyses. The agglomerated particles of hexagonal, spherical, and parallelogram shape are observed in the TEM images. The chemical elements, binding energies as well as La metal states on the surface of these synthesized NPs were determined using XPS. La2O3 NPs for good biological activities regarding antibacterial and anti-inflammatory potentials could be utilized in different biological applications to the food and biomedical industries. La2O3-IL has a high percentage of inhibitions than La2O3 and standard diclofenac.

Meso-macro numerical modeling of noncircular braided composite parts based on braiding process parameters

In the past few decades, the applications of composite structures reinforced with braided preforms have been growing increasingly in various industries due to their intrinsic properties. Therefore, their mechanical properties are worth studying experimentally, analytically and numerically. In this respect, the goal of the current study is to perform a finite element modelling on biaxially and triaxially braided composites with constant arbitrary cross-section. Thus, the braid angles formed by clockwisely and counter-clockwisely moving of carriers on noncircular parts, have been initially demonstrated to be unequal, unlike in circular parts. As a result, considering a parallelogram shape for the representative unit cell (RUC), the geometrical relationships for a RUC of 2D biaxially and triaxially braided composite are derived and implemented in VUMAT subroutine. Then, after determination of 3D effective stiffness matrix for each RUC, the finite element modelling is performed to predict bending behavior of final braided composite part. In these simulations, the stiffness variation all over the part is considered and mechanical behavior of composite parts is predicted based on the initial parameters of the braiding process. The obtained results from both experimental and simulations showed an acceptable agreement.