Frustum Of Pyramid Research Articles

A novel 3D Z-shape design of compression-twist coupling metamaterial

Compression-twist coupling (CTC) metamaterials are the type of mechanical metamaterials which can convert the axial deformation into circumferential deformation. In order to design CTC metamaterials, connecting two lattice layers with chiral oblique rods is an effective method, and the unit cell is a cube with 2D Z-shape structure on the lateral side. In this study, a new 3D spatial Z-shape CTC structure is firstly proposed by rotating the upper layer with different angles in the traditional 3D Z-shape structure. Then, the torsion angles are analyzed with changes of unit cell geometries by theoretical method, finite element simulation and experiments. Finally, by extending the new 3D Z-shape structures, the typical pyramid frustum and oblique-rod-enhanced structures are designed and their mechanical behaviors are studied.

Changes in monthly surface area, water level, and storage of 194 lakes and reservoirs in the Yangtze River Basin during 1990–2021 using multisource remote sensing data

Long-term, high spatiotemporal resolution of surface water area, water level, and storage changes in the Yangtze River Basin (YRB) has great scientific and practical importance for improving the management of water resources. Here, three distinct area estimations were first derived using the water classification enhancement method, automated water extraction method based on random forest, and the modified normalized difference water index. The optimized area data was determined by comparing against Sentinel-2 with the minimum root mean square error. A new area data was constructed with the optimized area as the primary data, while the remaining datasets were employed to fill in gaps. The elevation-area relationship was used to derive monthly water level. Changes in water storage were calculated by applying the pyramidal frustum formula from surface water area and water level data. Finally, a new comprehensive dataset of the monthly area, level, and storage changes in the 119 lakes and 75 reservoirs across the YRB with area larger than 10 km2 from 1990 to 2021 were first reconstructed. The spatiotemporal trends of surface water area/level/storage in lakes and reservoirs over 11 sub-basins of the YRB were quantified from 1990 to 2021, as well as before (1990–2003) and after (2003−2021) the construction of the Three Gorges Dam (TGD). During 1990–2021, there was a marked decrease in surface water area/level/storage in most of the YRB sub-basins, which contain 79 % of the lakes and 30 % of the reservoirs. After TGD was constructed, the surface water in lakes decreased by 10 %, while that of reservoirs remained consistent with the pre-construction. The surface water area/level/storage in the lower sub-basins of YRB exhibited a decline to an upward trend before and after the construction of TGD. This study provides a new comprehensive dataset for understanding the dynamic changes of water resource and climate change.

Experimental and numerical response and failure of laterally impacted carbon/glass fibre-reinforced hybrid composite laminates

The paper presents low-velocity impact tests and finite element simulations of carbon/glass fibre-reinforced hybrid composite laminates struck by a pyramidal frustum impactor in order to examine crushing deformations and failure mechanisms. Three mass ratios between the carbon and glass fibre (1:2, 1:1 and 2:1) are considered to compare the influence of the fibre hybridisation on the impact resistance of these laminates. This investigation is an essential step in the design process when ship structural crashworthiness is considered. The experimental results are presented in terms of the force-displacement responses and permanent deformations. Aspects of particular relevance to the deformation and fracture behaviour of hybrid-composite structures subjected to accidental loads are discussed, especially fibre/matrix debonding and fibre damage. Glass fibre shows better impact resistance than carbon fibre, despite the higher modulus of the latter. A series of simulations performed by the LS-DYNA finite element solver are used to calibrate the material failure criteria based on the experimental data, and the sensitivity of the failure criteria to mesh sizes is investigated.

Assembly of DNA triangular pyramid frustum for ultrasensitive quantification of exosomal miRNA

Early screening of biomarkers benefits therapy and prognosis of cancers. MiRNAs encapsulated in tumor-derived exosomes are emerging biomarkers for early diagnosis of cancers. Nevertheless, traditional methods suffer certain drawbacks, which hamper their wide applications. In this contribution, we have developed a convenient electrochemical approach for quantification of exosomal miRNA based on the assembly of DNA triangular pyramid frustum (TPF) and strand displacement amplification. Four single-stranded DNA helps the formation of primary DNA triangle with three thiols for gold electrode immobilization at the bottom and three amino groups on overhangs for the capture of silver nanoparticles. On the other hand, target miRNA induced strand displacement reaction produces abundant specific DNA strands, which help the DNA structural transition from triangle to TPF. Amino groups are thus hidden and the declined silver stripping current can be used for the evaluation of target miRNA concentration. This biosensor exhibits excellent analytical performances and successfully achieves analysis of exosomal miRNAs from cells and clinical serum samples.

Effect of Carrier Gas Flow Rate on the Morphology and Luminescence Properties of CsPbBr3 Microcrystals

All-inorganic halide perovskites, especially lead perovskite microcrystals, have attracted more and more attention because of their excellent photoelectric properties and chemical stability. Herein, high quality CsPbBr3 microcrystals with three different stable morphologies, namely microplate, frustum of a square pyramid and pyramid, were synthesized by the chemical vapor deposition (CVD) method through altering the flow rate of a carrier gas and were comparatively studied in structure and optical property. The photoluminescence (PL) results showed that the CsPbBr3 microplate has the best luminescence property. The structural characterization results by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray rocking curves (XRC) and Raman revealed that the flow rate of the carrier gas could manipulate the morphology evolution of CsPbBr3 microcrystals and further impact their luminescence properties.

High Cadence Monitoring of Reservoir Volume Fluctuations Using PlanetScope Imagery

Satellite images, which are effectively used to monitor changes in water areas, water management and planning, and to determine the measures to be taken against possible natural disasters, provide data with high temporal and spatial resolution. This study represents the monitoring of temporal surface water dynamics and estimating the volume fluctuations by combining the in-situ data with remotely sensed area data for Kemer Dam, containing the Arapapıştı Canyon (Turkey). Also, it demonstrates the production of the underwater topography in the water reservoir areas of absent or difficult to obtain bottom topography by integrating the in-situ water level and the PlanetScope Remote Sensing data in GIS environment. The temporal changes of dynamic volume of the reservoir above the lowest water level were estimated by the Hypsometric Relationship equation, Pyramidal Frustum Model and TIN-based Calculation method and their accuracy were evaluated using in-situ data. The simplicity and ease of application of the Pyramidal Frustum method, as well as its relatively low RMSE and Standard Error Rate of the Regression (SER) values, compared to other methods in this study, increase its usability in such studies. PlanetScope Imagery will make an important contribution to hydrological studies by producing daily images in high-resolution. Mission characteristics of satellite images (e.g. spatial, temporal and spectral resolution and, geometric accuracy), data sparseness, concurrency in parameters, chosen volume calculation method and linearity of hypsometry are important components that affect the performance of the Volume Fluctuation Monitoring studies using satellite images.

Using Multisource Satellite Data to Investigate Lake Area, Water Level, and Water Storage Changes of Terminal Lakes in Ungauged Regions

Lake area, water level, and water storage changes of terminal lakes are vital for regional water resource management and for understanding local hydrological processes. Nevertheless, due to the complex geographical conditions, it is difficult to investigate and analyze this change in ungauged regions. This study focuses on the ungauged, semi-arid Gahai Lake, a typical small terminal lake in the Qaidam Basin. In addition to the scant observed data, satellite altimetry is scarce for the excessively large fraction of outlier points. Here, we proposed an effective and simple algorithm for extracting available lake elevation points from CryoSat-2, ICESat-2 and Sentinel-3. Combining with the area data from Landsat, Gaofen (GF), and Ziyuan (ZY) satellites, we built an optimal hypsographic curve (lake area versus water level) based on the existing short-term data. Cross-validation was used to validate whether the curve accurately could predict the lake water level in other periods. In addition, we used multisource high-resolution images including Landsat and digital maps to extract the area data from 1975 to 2020, and we applied the curve to estimate the water level for the corresponding period. Additionally, we adopted the pyramidal frustum model (PFM) and the integral model (IM) to estimate the long-term water storage changes, and analyzed the differences between these two models. We found that there has been an obvious change in the area, water level, and water storage since the beginning of the 21st century, which reflects the impact of climate change and human activities on hydrologic processes in the basin. Importantly, agricultural activities have caused a rapid increase in water storage in the Gahai Lake over the past decade. We collected as much multisource satellite data as possible; thus, we estimated the long-term variations in the area, water level, and water storage of a small terminal lake combining multiple models, which can provide an effective method to monitor lake changes in ungauged basins.

Ethnomathematics: geometric analysis of historical buildings ngawen temple in Magelang

The analysis of historical buildings Ngawen Temple has a purpose of knowing the history and knowing the approach to the geometry. This type of research is descriptive research with a qualitative approach. The data collection techniques used in this research are interviews and documentation (observation) directly. The interview was done with the temple officers who were around the building, and the documentation was taken directly. The data analysis technique is done by analyzing the buildings related to the geometry, such as the shape of the building on the Ngawen temple. The results of this study were obtained namely, Ngawen Temple set in Buddhism. The Ngawen temple complex consists of five temples that line the parallel from north to south. Temple building facing the east. From the south of Ngawen Temple I, II, III, IV, and V, with each temple to plan the square. One of the uniqueness of Ngawen temple is the existence of 4 lion statues in every corner of temple II and temple IV. The shape of the Ngawen temple resembles the geometry of the cuboid, the rectangular pyramidal frustum, and the rectangular pyramid.

Comparative Seismic Analysis of Conical and Pyramidal Frustum Shaped Commercial Building (G+6) at Janakpuri, Delhi

In the modern building construction, the trend of constructing structures that are economical as well as aesthetically appealing is increasing. These structures often employ ideas and architectural features that are diverse from the emblematic conventional structures. The unconventionally shaped building has irregularities in the distribution of mass, stiffness and strength along the height of the building. Conical and pyramidal frustum shaped building are those structures that have remarkable shape and utilizes both inclined and vertical columns. In these structures, the floor area of the plan changes at each specific storey. With the intensification in complexity and innovation of the building construction, earthquake forces have become an imperative factor to be considered while construction of these avantgarde structures. The Indian Standard code IS-1893: 2002 (Part-I) describes the approach for the structures with irregularities considering the varying mass, floor-area ratio and stiffness of the storeys. The objective of the paper is systematic seismic analysis of a conical and pyramidal frustum shaped commercial building(G+6) at Janakpuri, Delhi using STAAD. Pro V8i. The buildings are located in seismic zone IV. The result of the analysis aids to understand and compare the storey drift, storey displacement and stiffness of the structures subjected to earthquake forces.

ANALYSIS OF HISTORICAL BUILDINGS NGAWEN TEMPLE IN MAGELANG

The analysis of historical buildings Ngawen Temple has a purpose of knowing the history of Ngawen Temple and knowing the approach to the Ngawen Temple's geometry. This research type is descriptive research with a qualitative approach. The subject of this research is the historical building of Ngawen Temple. The data collection techniques used in this research are interviews and documentation (observation) directly. The interview was done with the temple officers around the building, and the documentation was taken directly. The data analysis technique is done by analyzing the buildings related to the geometry, such as the building's shape on the Ngawen Temple. The results of this study were obtained; namely, Ngawen Temple set in Buddhism. The Ngawen Temple complex consists of 5 (five) temples that line the parallel from north to south. Temple building facing the east. From the south of Ngawen Temple I, II, III, IV, and V, each temple plans the square. One of Ngawen Temple's uniqueness is the existence of 4 lion statues in every corner of temple II and Candi IV. Another uniqueness is the temple's architecture, found in a lion's statue that supports the four sides of the temple building reconstructed from the five buildings. The lion statue's carved style resembles the lion symbol of Singapore's country and serves the rainwater that comes out through the statue's mouth. The Ngawen Temple's shape resembles the cuboid's geometry, the rectangular pyramidal frustum, and the rectangular pyramid

Theoretical study on optoelectronic properties of GaAs nanostructures

In this paper, GaAs frustum of a cone, cone, frustum of a hexagonal pyramid and hexagonal pyramid array models were designed (frustum is a portion of a cone or pyramid after the top is removed), and the influence of geometric parameters on the photoelectric emission characteristics was studied. And we used MATLAB to calculate and analyze the influence of geometric parameters on the carrier distribution and quantum efficiency of nanostructures. It is found that increasing the bottom diameter of the pyramid can effectively improve the optoelectronic characteristics of the photocathode. Compared with the cone structure, the frustum structure array has better light absorption characteristics in the short wave region, and has better quantum efficiency.

Polymer self-heating during incremental forming

• Polymer sheets are formed by Incremental Forming with the aid of frictional heating. • The temperature is controlled as a function of tool rotation and traveling speed. • The influence of the temperature on significant process features is investigated. • A thermo-mechanical numerical model is developed with a commercial FEM code. • A phenomenological model of the heat exchange is described. The study investigates the suitability of friction heating, generated by the forming tool rotation, to form polymer sheets during single-point incremental forming, and the possibility to control the temperature of the sheet by the selection of proper processing parameters. Polycarbonate sheets were formed to produce a square pyramid frustum geometry, varying the tool rotation speed and the traveling speed and monitoring the temperature. Load measurements were performed during the process, as well as the evaluation of the surface roughness and the elastic springback, to determine the influence of these processing conditions. Moreover, a thermo-mechanical numerical model was developed to understand the main phenomena involved. The results confirmed that the processing temperature, which increases with the tool rotation speed and decreases with the traveling speed, influences the sheet forming process and can be controlled by the selection of the processing speeds. A phenomenological model of the heat exchange was introduced to better explain the temperature evolution during the process and how it is influenced by the processing speeds.

Mechanism of twist in incremental sheet forming of thermoplastic polymer

Single point incremental forming (SPIF) is one of the procedures with the most potential in aerospace development and human implants. However, twist phenomena occur frequently and affect the processing defects, which strongly influence the geometric accuracy of the formed parts. This work reveals the mechanism of twist phenomena in detail and figures out the optimal solution of the principal challenge during industrial application and artificial bone processing by SPIF. A new analytical model is proposed to calculate the twist angle based on the law of conservation of energy. Meanwhile, a novel alternate spiral tool trajectory is established according to the linear interpolation of the two adjacent contour lines. Based on the case studies including pyramid frustum shape with constant wall angle and truncated cone shape with varying wall angle, SPIF formed parts by using the alternate spiral trajectory are compared with that by traditional unidirectional spiral trajectory, to effectively understand the advantages of the developed tool trajectory strategy. It shows that the proposed alternate spiral trajectory provides an effective way to effectually restrain the twist, and finally improves the geometric accuracy of target part in practical application of SPIF.

Volumetric shrinkage estimation of benchmark parts developed by rapid tooling mold insert

This paper estimates the volumetric shrinkage for thermoplastic Polypropylene (PP) injection molded components made using digital Acrylonitrile butadiene styrene (ABS) mold. The parameters affecting volumetric shrinkage for the digital ABS mold are mold temperature and injection temperature, cooling time, hold pressure and injecting speed. Therefore, twelve standard benchmark CAD model were selected with different geometric attributes. Subsequently, simulation analysis was performed on all CAD model using Moldflow® (MFA) simulation software. Additionally, regression analysis is applied to identify the effect of injection molding parameters on the volumetric shrinkage of part made using rapid tooling mold insert of digital ABS material. It is found that maximum volumetric shrinkage (18.75%) is observed for square pyramid frustum, conical frustum, and solid torus. On the contrary, hollow rectangular prism shows minimum shrinkage effect having 12.61% of volumetric shrinkage. This study predicted that shrinkage is the main concern for these three geometric features (i.e., square pyramid frustum, conical frustum, and solid torus) and must be looked for its minimization. The results are experimentally validated, with 3D scanner integrated with COMET plus and Inspect plus softwares. Since shrinkage estimation for digital ABS mold using Rapid Tooling technique has not been attempted before, therefore, this study provides guidance for the optimum parameter selection and assigning suitable shrinkage compensation values for digital ABS mold made using direct rapid tooling.

Design of the novel hot incremental sheet forming experimental setup, characterization of formability behavior of polyether-ether-ketone (PEEK)

In this work, a novel incremental sheet forming assisted by heat transfer through radiation was developed to improve the formability of PEEK. By means of a series of experiments forming PEEK sheets to the pyramid frustum with constant wall angle (CWA) and varying wall angle cone (VWA), the forming forces, formability, geometric accuracy, and twisting were recorded and analyzed. Different roles of the step down and temperature during the forming process were identified and discussed. The micro-mechanism of fracture was revealed through characterization of the distinct fracture patterns by using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Experimental researches indicate that the developed forming process offers economical and technical benefits in artificial bone reconstruction by using PEEK.

Improvement of UV emission in ZnO thin film caused by a transition from polycrystalline to monocrystalline

ZnO thin films and ZnO nanostructures have good UV emission properties, which are ideal materials for preparing short-wavelength light-emitting devices. In this study, Fe-doped ZnO thin films were prepared by sol-gel method using ferric chloride as the doping source. Compared with undoped ZnO thin films, the UV emission of low-concentration Fe-doped ZnO thin films did not show significant changes. However, the UV emission of high-concentration Fe-doped (≥4 at.%) ZnO thin films was significantly enhanced and the refractive index had also increased largely. It is observed by a scanning electron microscope (SEM) that the high-concentration Fe-doped ZnO thin film has a two-layer structure: the upper layer is composed of the frustum of hexagonal pyramid (FHP) shaped nanostructures, and the bottom layer in contact with the substrate is composed of polycrystalline spherical grains. Selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM) show that the upper FHP-shaped nanostructure is a single crystal with high crystalline quality, while the bottom layer is polycrystalline. Therefore, the formation of single crystal ZnO nanostructures greatly improves the optical quality of ZnO thin films. At present, as far as we know, the experimental results of partially converting polycrystalline ZnO into single crystal ZnO to greatly improve the UV emission performance of ZnO thin films have rarely been reported. The ZnO thin film with a two-layer structure prepared here is a candidate material for preparing UV light-emitting devices.

Doping-induced transition from polycrystals to single crystals in ZnO thin films

The growth of high quality ZnO thin films is a hot research topic in the field of optoelectronic materials. In this study, high quality ZnO thin films with a double-layer structure were obtained by sol-gel method. Al-doping induced transition from polycrystals to single crystals in the ZnO thin films was found. The results show that Al-doping improves the c-axis orientation of ZnO thin films. When the Al-doping concentration is higher than 4at%, the frustum of hexagonal pyramid (FHP) shaped ZnO nanostructures are formed on the polycrystalline ZnO thin films surface. As the Al-doping concentration further rises, the areal density of the FHP-shaped nanostructures also gradually increases and the size becomes more uniform. Both SAED patterns and high-resolution TEM images indicate that the FHP-shaped ZnO nanostructures are single crystals. It is of great scientific significance to transform polycrystalline ZnO into single crystal ZnO by Al-doping combined with a simple heat-treatment process. Compared with pure ZnO thin films, the FHP-shaped nanostructures on the surface show better UV emission performance, suggesting these materials are ideal ones for the preparation of ZnO-based UV emitters. The authors propose that the growth mechanism of FHP-shaped ZnO nanostructure is a multi-step solid-solid reaction dominated by surface diffusion of zinc atoms.

Research on manufacturing of pyramidal frustum parts using single point incremental forming process

The incremental sheet metal forming is a flexible “die-less” process used to manufacture sheet metal parts in cold pressing domain. Especially talking about single point incremental forming, it is a process which does not require a special die to allow the sheet metal forming. To implement this process, a fixing device and a simple rounded tool are needed. The paper presents some research on the influence of a support plate upon the parts dimensional precision. Because, the main advantage of single point incremental forming process is the flexibility, in experiments, a fixing device that it was initial designed for incremental deformation of frustum cone parts, is used to deform pyramidal frustum parts. Different configurations of pyramidal frustum parts are simulated using a finite element method and a special software tool named TMPG, to check if the sheet material, deep drawing steel DC05, can be deformed without fracture. The manufactured parts are measured using a 3D scanner, and a comparison with the 3D CAD models of the original parts is made.

A Numerical-Experimental Investigation of the Wrinkling Defect in Incremental Forming of Thin Polycarbonate Sheets

Incremental forming is a relatively new technology, whose deformation strategy is similar to the layered manufacturing principle of rapid prototyping approach. It promises a flexible, short time and inexpensive way to form sheet products of metals or polymers. Conversely, the process suffers from some peculiars defects, like twisting and wrinkling, which can be particularly evident when forming thin thermoplastic sheets. With the aim to enhance understanding of the wrinkling phenomenon, an experimental campaign on the single point incremental forming of thin polycarbonate sheets and FE analyses were performed. In particular, fixed wall angle square pyramid frusta were incrementally formed by varying two parameters, i.e. their wall angle and the vertical step depth per revolution of the toolpath. The investigation of the forming forces, the deformation states and the sheets thinning highlights the effects of the combined action of the above-mentioned parameters and plans the way to predict the occurrence of the twisting defect.

Experimental and Numerical Investigation of the Influence of Process Parameters in Incremental Sheet Metal Forming on Residual Stresses

The aim of this study is to analyze the co-relation between the geometrical accuracy of parts formed by single-point incremental forming (SPIF) and the resulting distribution of the residual stresses induced in the material as a function of the different process parameters of the SPIF process. The study was performed for a pyramidal frustum manufactured by varying the process parameters of SPIF, i.e., tool diameter, tool step-down, and wall-angle. The hole-drilling strain gage method was used to determine the residual stresses in the manufactured pyramids. Further, small strips were laser cut from the pyramids, and the curvature of the strips was measured. The curvature of the strips is a result of the intensity and distribution of the residual stresses, which in turn depends on the selected values of the process parameters. A validated numerical model of SPIF was used to determine the residual stresses parallel and perpendicular to the direction of tool motion at the center of a strip cut from the numerical model in clamped, unclamped, and trimmed states. Further, the change in the bending moment of a strip that occurred upon unclamping and trimming was calculated. Experimental and numerical investigations reveal that the most significant parameter in residual stress build-up and the reduction of geometrical accuracy is the wall angle. Upon unclamping, the highest change in the residual stresses and bending moment occurred with the largest tool step-down and tool diameter. Upon trimming, the magnitude of the residual stresses and bending moment changed the most with the largest tool step-down in both directions, whereas the change was highest with the smallest tool diameter in the transverse direction of the tool motion. Furthermore, upon trimming, the geometric deviations were highest with the large wall angles in the transverse direction of the tool motion. Overall, the effect of changing process parameters on the residual stress state and geometrical accuracy was more pronounced in the transverse direction of the tool motion.