Circular Space Research Articles

Exploring a circular economy solution space A comparative study to develop automated optimisation workflows supported by machine learning for circular design problems

Embedding circular economy (CE) principles in early design requires iterative evaluation across multiple lifecycle phases, with trade-offs between objectives complicating the identification of best solutions. This paper puts forward methods to automatically discover diverse, yet well-performing solution types within complex multi-objective CE design optimisation models. Working with a parametric model derived from a furniture design for CE case study, a comparison is made between weighted-sum single objective optimisation and multi-objective optimisation augmented with clustered solution types targeted by the reference point-based NSGA-II optimisation algorithm. Efficiency of optimisation, quality of results and distinctiveness of solution types presented by each method is compared in an effort to understand which will best assist designers to manage complexity in CE design. The generalisability of the presented methods to larger scale CE design problems is discussed and future areas of work on computational design for CE are extrapolated from the presented results.

Measuring accessibility of movement challenged persons during earthquake evacuation of Dhaka City, Bangladesh: A participatory GIS-Based approach

Although evaluation of the accessibility of people with disability (PWDs) is necessary to design effective transportation policy measures to ensure better mobility for PWDs, little empirical research are available on this subject. This study thus aims to address this gap by developing a methodological framework and applying this framework to assessing the accessibility of earthquake evacuation routes for people with movement-related disabilities (PMDs), one type of PWDs, in the city of Dhaka, Bangladesh. Specifically, this comprehensive accessibility index is composed of four components including accessibility from home to shelter, perceived accessibility of evacuation route, accessibility of entrance of the shelter, perceived accessibility of internal circular space and entrance of the residential building. Participatory GIS approach is employed in the data collection 455 PMDs were surveyed from 13 wards of Dhaka. Accessibility of each considered parameter and the overall indicator are poor in most cases. 45.2% of the wards are found to have relatively poor conditions of overall accessibility during evacuation. Relations of various accessibility components with socio-economic factors and level of disability are examined as well. PMDs with higher levels of disabilities and older PMDs perceive lower accessibilities of evacuation routes, circulation space, and entrance gate of residence, while male and more educated PMDs perceive circular space and entrance gate of residence to be more accessible.

An automated topology optimization interpreter that generates space frames

This paper presents the methodology and theoretical foundation of topology optimization (TO) Results Spaceframe Interpreter, an automatic TO results interpreter that generates a closely associated space frame consisting of welded structural tubing or rectangular bars. TO is a computational technique that uses a finite element (FE) formulation to identify the most weight-efficient structure within a design domain. Density-based TO results in structures that take organic forms and is usually a tedious and cumbersome process to generate a computer-aided-design (CAD) model to manufacture through conventional techniques. The optimal topology frequently resembles a space frame, which is well-known as being a rigid, lightweight structure. The methodology of the TO results interpreter leverages several techniques from volumetric image processing and has four primary processes. First, the results are obtained from commercial FE/TO software and mapped into a cubic grid of voxels. Second, junction locations are extracted and member connectivity that represents a frame is identified. Third, a sizing optimization is incorporated to determine appropriate sectional dimensions of the circular or rectangular space frame members. Fourth, the optimized space frame geometry is imported into a CAD design tool to automatically create a design model. The logic and are implemented within the frame extraction processes. The automated TO interpreter is designed to interact with commercial FE analysis and CAD systems. The interpreter is demonstrated on various spatial examples including aerospace and automotive applications. In each case, the welded space frame closely resembles the TO result, with nearly equivalent stiffness and mass.

Extracting statistical information about shapes in the visual environment

It is well known that observers can use so-called summary statistics of visual ensembles to simplify perceptual processing. The assumption has been that instead of representing feature distributions in detail the visual system extracts the mean and variance of visual ensembles. But recent evidence from implicit testing using a method called feature distribution learning showed that far more detail of the distributions is retained than the summary statistic literature indicates. Observers also encode higher-order statistics such as the kurtosis of feature distributions of orientation and color. But this sort of learning has not been shown for more intricate aspects of visual information. Here we tested the learning of distractor ensembles for shape, using the feature distribution learning method. Using a linearized circular shape space, we found that learning of detailed distributions of shape does not occur for this shape space while observers were able to learn the mean and range of the distributions. Previous demonstrations of feature distribution learning involved simpler feature dimensions than the more complex shape space tested here, and our findings may therefore reveal important boundary conditions of feature distribution learning.

Development of a Scaffold-on-a-Chip Platform to Evaluate Cell Infiltration and Osteogenesis on the 3D-Printed Scaffold for Bone Regeneration.

Developing a scaffold for efficient and functional bone regeneration remains challenging. To accomplish this goal, a "scaffold-on-a-chip" device was developed as a platform to aid with the evaluation process. The device mimics a microenvironment experienced by a transplanted bone scaffold. The device contains a circular space at the center for scaffold insert and microfluidic channel that encloses the space. Such a design allows for monitoring of cell behavior at the blood-scaffold interphase. MC3T3-E1 cells were cultured with three different types of scaffold inserts to test its capability as an evaluation platform. Cellular behaviors, including migration, morphology, and osteogenesis with each scaffold, were analyzed through fluorescence images of live/dead assay and immunocytochemistry. Cellular behaviors, such as migration, morphology, and osteogenesis, were evaluated. The results revealed that our platform could effectively evaluate the osteoconductivity and osteoinductivity of scaffolds with various properties. In conclusion, our proposed platform is expected to replace current in vivo animal models as a highly relevant in vitro platform and can contribute to the fundamental study of bone regeneration.

Design of wideband circularly polarized metasurface antenna using characteristic mode analysis

AbstractA wideband circularly polarized metasurface antenna using characteristic mode analysis is presented in this letter, which is composed of two‐layer substrate, 4 × 4 circular patch metasurface, L‐slot, transmission line, and air spacing. Through mode analysis, the metasurface structure can significantly enhance the bandwidth and gain of the antenna, and realize circular polarization (CP). After excitation, the air spacing and the L‐slot can realize 90° difference between the characteristic angles of the two modes of the metasurface, and finally radiate CP. The measurement results show that the prototype has a −10 dB impedance bandwidth from 5.6 to 8.2 GHz (37.7%), a 3‐dB axial ratio bandwidth from 6.2 to 7.8 GHz (22.9%), and a peak gain of 8.7 dBi at 6.4 GHz.

On the Necessity to Replace the Spherical Shape of Black Holes with a Disc Shape and Doubling their Energy

At the present time, black holes are reduced to the parameters of the Schwarzschild sphere. It is shown that Schwarzschild determined only half of the mass and energy of a black hole, and its spherical shape makes it difficult to interact with the external environment. The elimination of this drawback is the main goal of this work, and the substantiation of the shape, structure and parameters of black holes on the basis of the strict laws of the material world is its scientific novelty. The Methods of Research: Used in the work are based on deduction and induction, as well as on the application of reliable laws of physics and the general principles of the theory of knowledge. Work Results: It is proposed to replace the Schwarzschild sphere at the quantum level of the material world with a hole-die, which consists of 2 layers of hexagonal prisms of circular space quanta, formed from 6 regular trihedral prisms of elementary space quanta. The length of all their faces is λG =4.05126∙10-35m and is equal to the wavelength of the gravitational field forming this hole. Its energy and mass are doubled to the energy E = mc2 due to the rotation of the gravitational field in it. The radical change of the disk hole-die by concentric columns per λG quantum is justified. A possible connection between black and white holes is shown. Conclusion: Strict calculated dependences are found and numerical values are obtained on their basis, confirming the new parameters of disk-shaped black holes.

Active shape control for flexible space structures using an optimal gyricity distribution

An active shape control approach for a circular flexible space structure is studied. The shape of these flexible structures may need active shape control due to some particular mission objectives. For example, antenna reflectors may have requirements for their shape accuracy to guarantee communication performance; and some solar sails may change their shape to realize different commissions during interplanetary flight. This paper investigates an active shape control process executed by the gyricity (stored angular momentum) distribution existing in the circular flexible space structure. The shape of the circular flexible space structure is expected to be reformed from a plane plate to a paraboloidal plate. An optimal gyricity distribution is derived based on the optimal control theory for systems described by partial differential equations. Distributed forces can be generated by the optimal gyricity distribution in a rotating field to implement the active shape control. The dynamic model of the circular flexible space structure is established for the active shape control through the finite element method. Numerical simulation validates the functionality of the shape control method, and illustrates the shape-adjusting process of the circular flexible space structure.

Detections of the position-vectors of the multi targets located in a circular space based on an asymmetric coupling semiconductor lasers network.

We present a novel scheme for the detections of the position-vectors of the multi targets distributed in a circular space using multi channels of the probe chaotic waves emitted by the asymmetric coupling semiconductor lasers network (ACSLN), where these probe waves possess the attractive features of the time-space uncorrelation and wide bandwidth. Using these features, the accurate measurement for the position-vectors of the multi targets can be achieved by correlating the multi channels of the probe waves with their corresponding reference waves. The further research results show that the detections for the position-vectors of the multi targets possess very low relative errors that are no more than 0.22%. The ranging-resolutions for the multi targets located in a circular space can be achieved as high as 3 mm by optimizing some key parameters, such as injection current and injection strength. In addition, the ranging-resolutions exhibit excellent strong anti-noise performance even when the signal-to-noise ratio and relative noise intensity appear obvious enhancement. The detections for the position-vectors of the multi targets based on the ACSLN offers interesting perspectives for the potential applications in the driverless cars and the object tracking system with omnidirectional vision.

Scattering of fermionic isodoublets on the sine-Gordon kink

The scattering of Dirac fermions on the sine-Gordon kink is studied both analytically and numerically. To achieve invariance with respect to a discrete symmetry, the sine-Gordon model is treated as a nonlinear sigma -model with a circular target space that interacts with fermionic isodublets through the Yukawa interaction. It is shown that the diagonal and antidiagonal parts of the fermionic wave function interact independently with the external field of the sine-Gordon kink. The wave functions of the fermionic scattering states are expressed in terms of the Heun functions. General expressions for the transmission and reflection coefficients are derived, and their dependences on the fermion momentum and mass are studied numerically. The existence condition is found for two fermionic zero modes, and their analytical expressions are obtained. It is shown that the zero modes do not lead to fragmentation of the fermionic charge, but can lead to polarization of the fermionic vacuum. The scattering of the diagonal and antidiagonal fermionic states is found to be significantly different; this difference is shown to be due to the different dependences of the energy levels of these bound states on the fermion mass, and is in accordance with Levinson’s theorem.

Numerical Study of the Bubble Behavior of a Ladle with Different Purging Plug Designs

The purging plug determines the downtime and usage efficiency of the ladle‐refining process. Therefore, the optimization of its geometry can improve the ladle performance. Herein, suitable boundary conditions for numerical simulations are derived by combining water model experiments with numerical simulations. Furthermore, the influence of various parameters, such as the distribution shape of the circular slits and spacing between the circles on the bubble size, is investigated. The results show that rectangular distribution facilitates the reduction of bubble size compared to circular distribution because of the larger slit spacing to bubble diameter () of the rectangular distribution. In addition, distributing more circular slits around the edge of the purging plug reduces the pressure gradient generated by the velocity difference from the center of the bubble plume to the sides and increases , which can decrease the probability of coalescence. Therefore, it is beneficial to reduce the overall bubble size in the ladle when the circular slits are more distributed at the edge of the purging plug.

Representing and Experiencing Islamic Domes: Images, Cosmology, and Circumambulation

Lindsay Jones developed the concept of “ritual-architectural event”, according to which the meaning of a sacred building depends upon the participant’s experience of it in the course of the rituals they perform. Starting from such approach, and taking the Islamic dome as my subject-matter, I examine the correlations that link architectural forms, ritual performance, and participants’ experience into a whole. I first survey a corpus of images related to domes in two types of manuscripts (poetry, and pilgrimage narratives), showing how these images suggest cosmological patterns. The second part unfolds these representations, proceeding from cosmology to ritual. The third and last part focuses on circumambulation as the ritual experience that best embodies the previously identified cosmological patterns. The connection between the three dimensions discussed here is ascertained by the fact that the combination of circle and square structures relates both to Islamic graphic representations and ritual practices. An aesthetic/spiritual experience is awakened both in the mind and in the bodily senses of the viewer/practitioner: When Muslims stand under a dome, in front of the mihrab, thus facing Mecca, and when they behold the dome under which they stand, the view of this circular space possibly translates into a kind of mental and spiritual circumambulation. The conclusion suggests that the meaning attached to sacred architecture places is triggered by a complex of interactions between patterns referred respectively to the mind, bodily actions, and cultural settings.

Influence of meteorological conditions and topography on the active space of mountain birds assessed by a wave-based sound propagation model.

The active space is a central bioacoustic concept to understand communication networks and animal behavior. Propagation of biological acoustic signals has often been studied in homogeneous environments using an idealized circular active space representation, but few studies have assessed the variations of the active space due to environment heterogeneities and transmitter position. To study these variations for mountain birds like the rock ptarmigan, we developed a sound propagation model based on the parabolic equation method that accounts for the topography, the ground effects, and the meteorological conditions. The comparison of numerical simulations with measurements performed during an experimental campaign in the French Alps confirms the capacity of the model to accurately predict sound levels. We then use this model to show how mountain conditions affect surface and shape of active spaces, with topography being the most significant factor. Our data reveal that singing during display flights is a good strategy to adopt for a transmitter to expand its active space in such an environment. Overall, our study brings new perspectives to investigate the spatiotemporal dynamics of communication networks.

Schwarzschild Sphere and Nastasenko Hole, Justification of their Structure and basic Parameters

At the present time, black holes are reduced to the parameters of the Schwarzschild sphere. It is shown that Schwarzschild determined only half of the mass and energy of a black hole, and its spherical shape makes it difficult to interact with the external environment. The elimination of this drawback is the main goal of this work, and the substantiation of the shape, structure and parameters of black holes on the basis of the strict laws of the material world is its scientific novelty. The Methods of Research: Used in the work are based on deduction and induction, as well as on the application of reliable laws of physics and the general principles of the theory of knowledge. Work Results: It is proposed to replace the Schwarzschild sphere at the quantum level of the material world with a hole-die, which consists of 2 layers of hexagonal prisms of circular space quanta, formed from 6 regular trihedral prisms of elementary space quanta. The length of all their faces is λG = 4.05125∙10-35m and is equal to the wavelength of the gravitational field forming this hole. Its energy and mass are added to the energy E = mc2 due to the rotation of the gravitational field in it. The connection between the hole-die and the black and white holes, which change radially to the quantum λG in concentric columns, is justified. Conclusions: Strict calculated dependences are found and numerical values are obtained on their basis, which confirm the new parameters of black holes.

Efficient numerical algorithm with the second-order time accuracy for a two-dimensional nonlinear fourth-order fractional wave equation

In this article, we construct an efficient numerical algorithm with the second-order time accuracy for a two-dimensional nonlinear fourth-order fractional wave equation. We introduce an auxiliary variable to transform the fractional fourth-order wave problem into a low order coupled system, and then integrate the resulting equations by using Riemann–Liouville fractional integral. For the obtained fractional integral system, we use the Crank–Nicolson scheme in time with the weighted and shifted Grünwald integral (WSGI) approximation and the finite element method in space to arrive at the fully discrete coupled system. We show the detailed numerical algorithms and carry out numerical tests by taking two two-dimensional examples on rectangular and circular space domains to verify the effectiveness and convergence efficiency for our algorithm.

Direction Finding and Tracking using Single-Ring Circular Array Antenna and Space Division Table

Single-ring circular array antennas can be applied to direction finding systems in order to use nose-section in other purposes, and the interferometry is a proper direction finding method to those systems. We usually make the interferometer baseline long enough to achieve good angular accuracy. However, an interferometer with baseline longer than a half-wavelength has the ambiguity problem. In this paper, we present a novel method for solving the ambiguity problem in interferometry systems. This technique is based on the amplitude comparison method and the space division table, and it can place a target within the angular region in which the ambiguity problem does not occur by roughly estimating direction-of-arrival. The Monte Carlo simulation results show that proposed method can effectively remove the ambiguity problem in the system.

SCHWARZSCHILD SPHERE AND NASTASENKO SPINNERET

The study of black holes deepens the understanding of the structure of the foundations of the material world and the Universe, which is an urgent and important task that has not yet been fully resolved. Its solution is the main goal of this work, and the substantiation of the shape and structure of black holes on the basis of strict laws of nature is its scientific novelty. The research methods used in the work are based on deduction and induction, on the application of reliable laws of physics and the general principles of the theory of knowledge. Other methods are partially taken into account, because this work is related to scientific discoveries, the search for which is difficult to formalize. Results and its discussion. The paper puts forward a hypothesis that at the quantum level of the material world, the Schwarzschild sphere should be replaced by a spinneret of two layers of hexagonal prisms of circular space quanta, which are formed by six regular trihedral prisms of elementary space quanta with face length λG = 4.05126×10-35 m, of equal to the length waves of the gravitational field that forms them. Conclusions. It is shown that the spinnerets radius R = λG and its mass change by quantum jumps, and its internal structure consists of cylindrical layers, the radius of which increases from the first axial cylinder to the peripheral one by the quantum value λG. The spinnerets can have the properties of a black and white hole, which corresponds to the principles of Einstein's GR.

Parabolic Boundary-Value Problems in a Piecewise Homogeneous Wedge-Shaped Cylindrically Circular Space

Parabolic Boundary-Value Problems in a Piecewise Homogeneous Wedge-Shaped Cylindrically Circular Space

Spatial voting models in circular spaces: A case study of the U.S. House of Representatives

The use of spatial models for inferring members’ preferences from voting data has become widespread in the study of deliberative bodies, such as legislatures. Most established spatial voting models assume that ideal points belong to a Euclidean policy space. However, the geometry of Euclidean spaces (even multidimensional ones) cannot fully accommodate situations in which members at the opposite ends of the ideological spectrum reveal similar preferences by voting together against the rest of the legislature. This kind of voting behavior can arise, for example, when extreme conservatives oppose a measure because they see it as being too costly, while extreme liberals oppose it for not going far enough for them. This paper introduces a new class of spatial voting models in which preferences live in a circular policy space. Such geometry for the latent space is motivated by both theoretical (the so-called “horseshoe theory” of political thinking) and empirical (goodness of fit) considerations. Furthermore, the circular model is flexible and can approximate the one-dimensional version of the Euclidean voting model when the data supports it. We apply our circular model to roll-call voting data from the U.S. Congress between 1988 and 2019 and demonstrate that, starting with the 112th House of Representatives, circular policy spaces consistently provide a better explanation of legislators’s behavior than Euclidean ones and that legislators’s rankings, generated through the use of the circular geometry, tend to be more consistent with those implied by their stated policy positions.

Flow regimes in a multi-gap circular Couette-Taylor system with opposite rotating cylinders

This work investigates the flow structure in the gaps of a multi-cylinder circular Couette-Taylor system, which is a model of a two-rotor heat generator. The initial information for studying the flow structure was data on the magnitude of the resistance torque to rotors opposed rotation, as well as on the nature of the amplitude-frequency spectrum of pulsations of this torque, depending on the viscosity of the working fluid and the rotational speed of the heat generator rotors. The obtained data allow comparing the nature of hydrodynamic processes in the single and obtained multi-gap circular space of Couette-Taylor and calculating the parameters of structural formations in the multi-gap working space of the heat generator. At relative rotational speeds of rotors (3-50) rad/s, the main energy of flow pulsations (up to 90%) is found in the amplitude-frequency spectra in the frequency range (12-70) Hz. It is associated with vortices first described by Taylor, which are extended low-frequency regularly alternating spirals and vortex structures with right and left rotation in the region of higher frequencies (200– 500) Hz; their frequency is determined by the width of the annular gaps of the multi-cylinder system.