Three-dimensional Space Structure Research Articles

Mechanical response of a novel square dome shell with bistable behavior: Improved analytical method and empirical model

In this study, a novel square dome-shaped shell with a fascinating bistable behavior is proposed, which is able to quickly switch to a new stable configuration within its elastic range under a certain load, due to its elastic instability. Compared to most circular shells currently studied, it is easier to arrange multiple structures in three-dimensional space to obtain multistable responses. Numerical and experimental methods were adopted for the study of the mechanical response of the square shell, and main influence parameters were also investigated. In addition, an improved piecewise fitting method is introduced to establish an empirical formula for predicting the mechanical response of bistable shells, which can be used to guide the design of bistable shells. Finally, two types of metamaterials, uniaxial compressible metamaterials and triaxial compressible metamaterials, are successfully designed according to the above theory, the typical behaviors of which are studied via simulations. This novel structure presented in this paper has broad application prospects in the fields of energy absorption and programmable deformation structures.

Two-Dimensional Self-Trapping Structures in Three-Dimensional Space

Two-Dimensional Self-Trapping Structures in Three-Dimensional Space

Scrutinizing and rooting the multiple anomalies of Nepal earthquake sequence in 2015 with the deviation–time–space criterion and homologous lithosphere–coversphere–atmosphere–ionosphere coupling physics

Abstract. The continuous increasing of Earth observations benefits geosciences and seismicity study but increases greatly the difficulties in understanding and discriminating multiple source data. Although the lithosphere–coversphere–atmosphere-ionosphere (LCAI) coupling paradigm and the deviation–time–space (DTS) criterion were presented for better searching for and understanding the potential seismic anomalies from multiple observations, the strict consistency of spatiotemporal characteristics and homologous physics of multiple-parameter seismic anomalies has not been investigated sufficiently. With the 2015 Nepal earthquake sequence being a typical case, the reported multi-parameter anomalies were systematically reviewed, and their space–time characteristics were summarized thoroughly in this study. Numerical simulation with refined geological structures in three-dimensional space revealed the inhomogeneous crustal stress field alteration (CSFA) along the faults and around the hypocenters of the 2015 Nepal earthquake sequence, which is expected to be the root of the seismic anomalies. The stress-activated positive charge carriers would have given rise to different responses near the ground surface (coversphere), including the microwave dielectric reduction, the additional infrared radiation, and the atmospheric ionization, which subsequently affected the physical properties of the atmosphere and the ionosphere and resulted in abnormal phenomena therein. Based on the DTS criterion and LCAI coupling paradigm, the seismic anomalies of the 2015 Nepal earthquakes were scrutinized strictly, and the retained anomalies were rooted carefully to the regional CSFA as well as its local blocking. Therefore, an integrated LCAI coupling framework with strict space–time correspondence and homologous physics in CSFA was proposed for the 2015 Nepal earthquake sequence. This research provides a definite philosophy as well as a practical solution for scrutinizing the rootable seismic anomalies from multi-parameter observations of earthquakes, which is of scientific meanings for searching earthquake precursors and reaching earthquake prediction.

Calculation of mass transfer process in vertical sedimentation tank and construction of CFD model

The development of a numerical model of mass transfer in a vertical pion is considered. The reconstruction was carried out in a room with a three-dimensional exchange of contaminants and a potential flow. Clear contrast plans were used for numerical integration. The results of the numerical study are presented in this paper. A quirk of the constructed numerical demonstration is the plausibility of agent-based calculation of structures in three-dimensional space. An auxiliary development of this work should be carried out by creating a mass transfer control model in settling tanks based on the model of a culminating liquid jet in a tornado vortex.

Sanism and Narrative Research: Making Room for Mad Stories

AbstractThis article considers challenges and possibilities that narrative researchers in music education might encounter when attempting to recount stories of Madness. Narrative restorying often follows a three-dimensional space structure that includes the commonplaces of temporality, sociality, and place (Clandinin, 2016; Clandinin et al., 2016; Clandinin & Connelly, 2000). Mad stories, however, do not easily restory into this structure. I center my own experiences of being bipolar to explore how such experiences particularly disrupt dimensions of temporality and sociality and assert that narrative researchers might learn to make room for Madness when telling stories. Moreover, I reflect on the impact of sanism—the oppression that Mad people experience—on Mad stories. In considering how narrative researchers might make space for Mad stories, I offer an expanded four-dimensional narrative structure alongside critical storytelling and draw upon the work of Patricia O'Toole (1994) and Roberta Lamb (1993–1994) to explore how researchers might represent such stories.

The Substructures in the Anticenter Region of the Milky Way

We investigated the observational properties of Triangulum-Andromeda (TriAnd), Monoceros Ring (MRi), and Anti-Center Stream (ACS) in the anticenter region using K giants, M giants, and RGB stars from LAMOST and SDSS survey. The Friends of Friends algorithm was applied to select member stars of these structures. We found a new spur of TriAnd at l ∼ 133° based on member stars selected in this work and compiled from the literature. The distributions of radial velocity and proper motion of its member stars indicate that TriAnd is gradually moving away from the Sun. The comparisons of [Fe/H] and [α/Fe] between TriAnd and thick-disk/halo stars reveal that TriAnd is likely to originate from the thick disk. MRi and ACS are adjacent in space with a boundary around latitude 30°, and there is no significant difference between the two structures in velocity, proper motions, and orbits. We suggested that MRi and ACS probably have a common origin. We made projections of the four structures in three-dimensional space for the exploration of the movements between the Sagittarius (Sgr) stellar stream and MRi, and found that a new spur was formed by the Sgr stream members in the velocity distribution as it passed through the MRi region.

Super-resolution acoustic imaging

This work reports a super-resolution acoustic imaging method that inverses source distribution, strength, and structure in three-dimensional space. The nonlinear coupling process between a low-frequency sound field and a high-frequency plane wave is endowed to break the resolution limit. The reconstructed results for different source strengths and frequencies demonstrate the capability of the proposed method. The results show that the proposed method is very suitable for low-frequency source imaging, which could strengthen the super-resolution analysis capability of acoustic imaging tests and, consequently, lead to deepened physical insights into various propulsion systems in underwater and aerospace systems.

Combining Cryo-EM Density Map and Residue Contact for Protein Secondary Structure Topologies.

Although atomic structures have been determined directly from cryo-EM density maps with high resolutions, current structure determination methods for medium resolution (5 to 10 Å) cryo-EM maps are limited by the availability of structure templates. Secondary structure traces are lines detected from a cryo-EM density map for α-helices and β-strands of a protein. A topology of secondary structures defines the mapping between a set of sequence segments and a set of traces of secondary structures in three-dimensional space. In order to enhance accuracy in ranking secondary structure topologies, we explored a method that combines three sources of information: a set of sequence segments in 1D, a set of amino acid contact pairs in 2D, and a set of traces in 3D at the secondary structure level. A test of fourteen cases shows that the accuracy of predicted secondary structures is critical for deriving topologies. The use of significant long-range contact pairs is most effective at enriching the rank of the maximum-match topology for proteins with a large number of secondary structures, if the secondary structure prediction is fairly accurate. It was observed that the enrichment depends on the quality of initial topology candidates in this approach. We provide detailed analysis in various cases to show the potential and challenge when combining three sources of information.

Rambutan-like CoP@Mo-Co-O hollow microspheres for efficient hydrogen evolution reaction in alkaline solution

Water electrolysis has attracted a lot of attention in recent years for hydrogen production. CoP has been widely investigated as a traditional electrocatalyst for hydrogen evolution reaction (HER). However, the strong bond strength of P–H bond and weak chemical stability are still the key problems in affecting catalytic performance of CoP. In this work, we synthesized rambutan-like CoP@Mo-Co-O hollow microspheres as HER electrocatalyst, solving the two problems of CoP as electrocatalyst. Benefiting from the unique three-dimensional space structure and interface effect between CoP and Mo-Co-O, the synthesized CoP@Mo-Co-O shows a small overpotential of 62 mV at the current density of 10 mA cm−2 for HER, which is much lower than the corresponding overpotential of pure CoP microspheres (117 mV). Rambutan-like CoP@Mo-Co-O hollow microspheres also show robust long-term stability and excellent cycling stability. This work provides a new method for the design and improvement of non-precious HER electrocatalysts.

Chemically functionalized cellulose nanofibrils-based gear-like triboelectric nanogenerator for energy harvesting and sensing

Cellulose is the most abundant natural polymer with low cost, high strength, good chemical modification property and biodegradability. In this work, a cellulose-based triboelectric material is prepared by surface amino modification and silver nanoparticle coating treatment of cellulose nanofibrils (CNFs), and a novel and simple CNF-based gear-like triboelectric nanogenerator (TENG) is designed. The three-dimensional space structure increases the frictional contact area by approximately four times compared with an ordinary planar structure. This gear-like structure shows good flexibility and integration, and the maximum open-circuit voltage can reach 286 V when three pairs of gear-like structures are assembled. The maximum power density is 0.43 W/m2 with a load resistance of 5 × 107 Ω, and the resulting electrical output can directly power 60 light-emitting diodes. Moreover, TENG exhibits exceptional sensitivity and responsiveness when used as a self-powered sensor. It can reflect the change in the state of human touch through electric signals and also respond to the changes in small forces caused by water drop and vibration in the substrate. This study not only introduces a green CNF-based triboelectric material, but also presents for the first time a high-performance TENG with a gear-like structure and applies it to self-powered sensing.

Non-negative constrained inverse eigenvalue problems – Application to damage identification

Abstract Damage identification using eigenvalue shifts is ill-posed because the number of identifiable eigenvalues is typically far less than the number of potential damage locations. This paper shows that if damage is defined by sparse and non-negative vectors, such as the case for local stiffness reductions, then the non-negative solution to the linearized inverse eigenvalue problem can be made unique with respect to a subset of eigenvalues significantly smaller than the number of potential damage locations. Theoretical evidence, numerical simulations, and performance comparisons to sparse vector recovery methods based on l 1 -norm optimization are used to validate the findings. These results are then extrapolated to the ill-posed nonlinear inverse eigenvalue problem in cases where damage is large, and linearization induces non-negligible truncation errors. In order to approximate the solution to the non-negative nonlinear least squares, a constrained finite element model updating approach is presented. The proposed method is verified using three simulated structures of increasing complexity: a one-dimensional shear beam, a planar truss, and a three-dimensional space structure. For multiple structures, this paper demonstrates that the proposed method finds sparse solutions in the presence of measurement noise.

Internal wave attractors in 3D geometries : A dynamical systems approach

We study the propagation in three dimensions of internal waves using ray tracing methods and traditional dynamical systems theory. The wave propagation on a cone that generalizes the Saint Andrew's cross justifies the introduction of an angle of propagation that allows to describe the position of the wave ray in the horizontal plane. Considering the evolution of this reflection angle for waves that repeatedly reflect off an inclined slope, a new trapping mechanism emerges that displays the tendency to align this angle with the upslope gradient. In the rather simple geometry of a translationally invariant canal, we show first that this configuration leads to trapezium-shaped attractors, very similar to what has been extensively studied in two-dimensions. However, we also establish a direct link between the trapping and the existence of two-dimensional attractors. In a second stage, considering a geometry that is not translationally invariant, closer to realistic configurations, we prove that although there are no two-dimensional attractors, one can find a structure in three-dimensional space with properties similar to internal wave attractors: a one-dimensional attracting manifold. Moreover, as this structure is unique, it should be easy to visualize in laboratory experiments since energy injected in the domain would eventually be confined to a very thin region in three-dimensional space, for which reason it is called a super-attractor.

Sub-6GHz 4G/5G Conformal Glasses Antennas

The difficulty of antenna design applied to glasses is that the structure of glasses is too single, and the space available for antenna design is greatly limited. In this background, the integrated design of 4G antennas and 5G antennas applied to glasses is proposed in this paper. The most important highlight of this design is that it makes full use of the limited three-dimensional space structure provided by glasses and achieves the perfect combination of the antenna and glasses in the physical structure. Specifically, two antennas for 4G communication are arranged on two glasses frames, and four antennas for 5G communication are arranged on two glasses legs. In this way, we can make full use of the space provided by the glasses to design antennas and ensure that there is a certain distance between the 4G antennas and 5G antennas so that the performance of both 4G antennas and 5G antennas can be guaranteed. The 4G antenna consists of a loop structure printed on the frame and leg of the glasses and a parasitic branch strip printed on the front of the leg of the glasses. The resonance modes of the 4G antenna are mainly loop, monopole, and dipole modes, which can cover two 4G bands of 0.824-0.96 GHz and 1.71-2.69 GHz. Each 5G antenna mainly comes from the open slot mode etched on the metal ground surface of an FR4 substrate of the glasses leg. In addition, the slot antennas operate in two 5G bands of 3.3-3.6 GHz and 4.8-5.0 GHz. Finally, the glasses and the antennas are fabricated based on FR4 substrates and measured. The measured results show that the proposed antennas perform well and have the potential to be used in 4G/5G communications through glasses.

Characterization of a Nanocrystalline Structure Formed by Crystal Lattice Transformation in a Bulk Steel Material

The formation of nanocrystalline structures in bulk metal materials is of great significance for both investigating the structural features of nanocrystalline materials and enhancing the value of bulk metal materials in engineering applications. Herein, we report a nanocrystalline structure formed by lattice transformation in a three-dimensional bulk metal material. We characterized its phase composition, three-dimensional features, and boundary structure. This nanocrystalline structure had microscale length and height and nanoscale width, which gave it a “nanoplate” structure in three-dimensional space. We observed edge dislocations in the interior of the nanocrystalline structure. A unique transitional boundary that contributed to maintaining its nanoscale size was found at the border between the parent phase and the nanocrystalline structure.

The Research of the Digital Core Construction Based on Marching Cubes

Digital core technology as a new numerical simulation method, through the core sample reflection of the real core of the complex internal structure, from the micro level in the theory study of core pore structure and residual oil and to improve oil recovery, to provide technical guidance for the production. In order to realize the core of the pore structure in three-dimensional space, this article will Micro - CT image and the Marching Cubes algorithm effectively, realize the three-dimensional reconstruction of digital core. First by using Micro - CT acquisition core section in CT scan images of different time, using the improved Marching Cubes algorithm, gives the method of constructing digital core, will the constructed three-dimensional digital imaging cores and realize the visualization of core pore structure model. The results show that the method presented in this paper the three dimensional data weight building, reconstruction results with complete data volume has the very good consistency, to verify the effectiveness of the new method and advanced.

Design and tailoring of patterned ZnO nanostructures for energy conversion applications

ZnO is a typical direct wide-bandgap semiconductor material, which has various morphologies and unique physical and chemical properties, and is widely used in the fields of energy, information technology, biomedicine, and others. The precise design and controllable fabrication of nanostructures have gradually become important avenues to further enhancing the performance of ZnO-based functional nanodevices. This paper introduces the continuous development of patterning technologies, provides a comprehensive review of the optical lithography and laser interference lithography techniques for the controllable fabrication of ZnO nanostructures, and elaborates on the potential applications of such patterned ZnO nanostructures in solar energy, water splitting, light emission devices, and nanogenerators. Patterned ZnO nanostructures with highly controllable morphology and structure possess discrete three-dimensional space structure, enlarged surface area, and improved light capture ability, which realize the efficient carrier regulation, achieve highly efficient energy conversion, and meet the diverse requirements of functional nanodevices. The patterning techniques proposed for the precise design of ZnO nanostructures not only have important guiding significance for the controllable fabrication of complex nanostructures of other materials, but also open up a new route for the further development of functional nanostructures.

The methodology of multicriterial assessment of Petri nets’ apparatus

This article emphasizes the effectiveness and relevance of the using of the apparatus of Petri nets for modeling of complex computing systems. Due to the fact that the methods of analysis existing in this theory do not allow estimating the resources required to build the desired model of the system, there is a problem of shortage of criteria for its evaluation in terms of the complexity of the construction. In the article we consider the method of analysis of a random Petri net based on the complexity of its building and relationships of internal units - subnets. The purpose of this article is a software implementation of such an assessment within the theory of PN structures. Due to the fact, that structural approach allows to perform the operation of decomposition of the original system, this model can be divided into subnets of minimal dimension, that will allow to make its quantitative assessment - ranking. To determine the total assessment of the input and output data of the system we will perform the analysis of head and tail positions of the net taking into account the weights of the input and output arcs of these positions. In order to identify an extent of the cost required to build the system, the number of operations of union of subnet transitions and positions. These subnets have minimal dimension in the original PN. Thus, the article demonstrates the formal implementation of assessment technique modules with using of algebra of sets, and the rules of splitting the PN structure into elementary blocks are formulated. The example of a comparative assessment of the two Petri nets based on the proposed complexity criteria is given; the plots of PN in different coordinate systems are displayed. The article presents the results of the research - a plot of PN structures in three-dimensional space, implemented using described software. It demonstrates the accuracy of PN assessment by structural analysis in comparing with a non-automated visual one. This approach can be applied for comparative assessment of computer systems in terms of complexity of their construction and size of input and output data.

Coordinated formation control design with obstacle avoidance in three-dimensional space

This paper considers a problem of coordination formation control for multiple unmanned vehicles based on the behavioral control and virtual structures in three-dimensional space. The repulsive forces effect among unmanned vehicles to avoid collision with others and move them to the balance points on the spherical surface whose center is the virtual leader. The unmanned vehicles do not have specific identities or roles within the formation. The proposed method does not require specific orders or positions of the unmanned vehicles. The formation can transform automatically when unmanned vehicles enter or exit the formation. This paper also proposes a technique for avoiding obstacles based on the behavioral structure. In this technique, when an unmanned vehicle gets close to an obstacle, while moving toward its target, two kinds of potential fields with rotational vectors are applied to lead the unmanned vehicle to avoid the obstacle. Simulations are also given to verify the effectiveness of theoretical results.

Wave-based control of under-actuated flexible structures with strong external disturbing forces

Wave-based control of under-actuated, flexible systems has many advantages over other methods. It considers actuator motion as launching a mechanical wave into the flexible system which it absorbs on its return to the actuator. The launching and absorbing proceed simultaneously. This simple, intuitive idea leads to robust, generic, highly efficient, precise, adaptable controllers, allowing rapid and almost vibrationless re-positioning of the system, using only sensors collocated at the actuator–system interface. It has been very successfully applied to simple systems such as mass–spring strings, systems of Euler–Bernoulli beams, planar mass–spring arrays, and flexible three-dimensional space structures undergoing slewing motion. In common with most other approaches, this work also assumed that, during a change of position, the forces from the environment were negligible in comparison with internal forces and torques. This assumption is not always valid. Strong external forces considerably complicate the flexible control problem, especially when unknown, unexpected or unmodelled. The current work extends the wave-based strategy to systems experiencing significant external disturbing forces, whether enduring or transient. The work also provides further robustness to sensor errors. The strategy has the controller learn about the disturbances and compensate for them, yet without needing new sensors, measurements or models beyond those of standard wave-based control.

Three-Dimensional Simulation of Virtual Plants Branch Structure Based on Quasi Binary-Tree and L System

In order to simulate the plant branch structure in three-dimensional space, and extract the growth more efficiently, this paper presented a new method to simulate the structure of plant branch based on quasi binary-tree structure and three-dimensional L system. The results of the actual trees simulation shows that this method can describe the plants branch structure efficiently and provide a new way for the simulation of plants.