Internal Spacer Research Articles

A new perspective on Kaluza–Klein theories

Assuming that the geometry of spacetime is uniquely determined by the energy–momentum tensor of matter alone, i.e. without any interactions, enables us to construct the Lagrangian from which the metric of higher dimensional spacetime follows. From the geodesic equations that follow, it becomes clear that the incorrect mass of elementary particles predicted by Kaluza–Klein theories arises from the assumption that in the absence of gravity the solution to the Einstein field equations reduces to the Minkowski metric. From construction of a consistent theory of 4D electromagnetism, we find that this assumption does not only result in the incorrect mass of elementary particles, but also the incorrect value of the cosmological constant. This suggests that these incorrect predictions, which are often regarded as major flaws of Kaluza–Klein theories, just reflect the inconsistency of the assumption that the solution to Einstein field equations reduces to Minkowski metric in the absence of gravity and Weyl invariance which is the symmetry of gauge theories in 4D spacetime. Abandoning this assumption results in modification of general relativity. We show that the unified description of fundamental interactions naturally incorporates the Higgs mechanism. For non-Abelian gauge fields, we find that the manifold comprising the extra dimensions has to be a group manifold and show that the standard model is realized in 16D spacetime. We show that charge and spin are the same concept, but what makes them different is that the former follows from symmetry of 4D spacetime while the latter follows from symmetry of the internal space.

Hierarchical Magnetic Carbon Nanoflowers for Ultra-Efficient Electromagnetic Wave Absorption.

Porous carbon nanomaterials are widely applied in the electromagnetic wave absorption (EMWA) field. Among them, an emerging flower-like carbon nanomaterial, termed carbon nanoflowers (CNFs), has attracted tremendous research attention due to their unique hierarchical flower-like structure. However, the design of flower-like carbon nanomaterials with different magnetic cores for EMWA has rarely been reported. Herein, a general template method is proposed to achieve a set of high-quality magnetic CNFs, namely Co@Void@CNFs, CoNi@CNFs, and Ni@CNFs. The prepared magnetic CNFs have highly accessible surface area and internal space, rich heteroatom content, multi-scale pore system, and uniform and highly dispersed magnetic nanoparticles, as a result, deliver superior EMWA performance. Specifically, when the thickness is 2.6mm, the Co@Void@CNFs exhibit a maximum refection loss (RLmax) of -56.6dB and an effective absorption bandwidth (EAB) from 8.0 to 12.1GHz covering the whole X band. The CoNi@CNFs have an RLmax of up to -57.6dB and a wide EAB of 5.6GHz at just 1.9mm. For the Ni@CNFs, possess an ultra-broad EAB of 6.1GHz, covering the entire Ku band at 2.0mm. Overall, the hierarchical magnetic carbon nanoflowers proposed here offer new insights toward realizing multifunctional integrated carbon nanomaterials for EMWA.

One Meter Triboelectric Nanogenerator for Efficient Harvesting of Meter‐Scale Wave Energy

AbstractTriboelectric nanogenerators (TENGs) are effective in harvesting high‐entropy low‐frequency wave energy, yet traditional TENGs struggle to align with the meter‐scale wavelengths prevalent in marine environments, significantly impairing their wave energy conversion efficiency. Addressing this, the One Meter TENG (OM‐TENG) is introduced, a pioneering advancement in TENG design that extends the shell size to 1 m. This innovation features a novel lantern‐shaped stacked silicon‐manganese steel sheet configuration, optimizing internal space usage, and achieving a single‐cycle transfer charge of 60.82 µC and a friction layer area density of 1.76 cm−1. Furthermore, by integrating a segmented limiter device for rational control of different sliders, effective contact separation among numerous TENG units is realized. Comprehensive evaluations through theoretical analysis, multiphysics field numerical simulations, sensor data analytics, and comparative experimental measurements have unequivocally demonstrated OM‐TENG's superior capability in capturing meter‐scale wave energy under actual environmental conditions, alongside its remarkable anti‐capsize performance. Achieving peak outputs of 584 V and 444 µA, OM‐TENG can power 96 2 W LEDs and drive wireless communication modules, marking a significant step forward in the efficient utilization of wave energy and the design of large‐scale TENGs.

Study on the noise reduction mechanism and application of the noise simulation analysis of care robots

Abstract Currently, robots on the market have varying operational requirements due to their different functions. The care robots are primarily used to serve people under care. Therefore, reducing the amount of noise they make while moving is important. This study measured their noise in an anechoic room. This study found that the most noise is produced when they move forward and backward at full speed. The robot’s vibration signal was measured and compared with the noise source to propose the most effective way to reduce the noise. Due to the robot's small internal space, methods for noise reduction are limited. The care robot’s development must adopt quick customizable 3D printing technologies, produce sound absorption/insulation materials independently, determine the best sound absorption/insulation material and structural configuration, use impedance tubes to measure the sound absorption coefficient and sound insulation performance, and select the appropriate materials and implement them into the robot for actual tests. These results indicate that the noise value of the main contributing frequency can be reduced by 15dB at most. Furthermore, this study also used an acoustic simulation analysis to calculate and simulate the vibration and noise of the care robot. The vibration and noise signals during the robot's operation were measured and compared to provide a reference for manufacturers in design. Finally, experimental materials were added to the simulation and compared with the noise reduction results. The results show similar trends. Therefore, the model developed in this study may provide a fast, low-cost, and feasible method for the noise reduction of care robots.

Flowing between string vacua for the critical non-Abelian vortex with a deformation of N=2 Liouville theory

It has been shown that non-Abelian solitonic vortex string supported in four-dimensional (4D) N=2 supersymmetric QCD (SQCD) with the U(2) gauge group and Nf=4 quark flavors becomes a critical superstring. This string propagates in the ten-dimensional space formed by a product of the flat 4D space and an internal space given by a Calabi-Yau noncompact threefold, namely, the conifold. The spectrum of low-lying closed string states was found and interpreted as a spectrum of hadrons in 4D N=2 SQCD. In particular, the lowest string state appears to be a massless Bogomol’nyi-Prasad-Sommerfield (BPS) baryon associated with the deformation of the complex structure modulus b of the conifold. It was recently shown that the Coulomb branch of the associated string sigma model which opens up at strong coupling can be described by N=2 Liouville theory. Building on these results we switch on quark masses in 4D N=2 SQCD and study the interpolation of the initial U(2) SQCD with Nf=4 quarks to the final SQCD with the U(4) gauge group and Nf=8 quarks. To find the true string vacuum which arises due to the mass deformation we solve the effective supergravity equations of motion associated with the deformed world sheet Liouville theory. We show that the massless BPS baryon b survives the deformation and that finding of the spectrum of low-lying massive hadrons in the final SQCD is linked to the Calogero problem. Published by the American Physical Society 2024

Evaluation of the Protection of Historical Buildings in Universities Based on RCM-AHP-FCE

The accumulation of years imbues historical buildings within universities with a profound sense of heritage, evident not only in the temporal imprints within their internal spaces but also in the evolution of their external surroundings. This cultural legacy subtly enriches students’ spatial awareness of history and fosters a collective memory of campus context. Current scholarly inquiry into university historical buildings primarily revolves around comprehensive considerations encompassing the preservation of these edifices, the overarching planning of academic institutions, and the safeguarding of the distinctive features inherent to historical structures. However, the predominant focus lies on qualitative analyses, leaving a pressing need for quantitative assessments and the establishment of an evaluation framework to gauge the efficacy of historical building preservation in academia. Addressing this gap, this study employs the Analytic Hierarchy Process (AHP) and Fuzzy Comprehensive Evaluation (FCE) to formulate the University Historical Building Protection Evaluation Framework (UHBPEF). Drawing from the examination and categorization of the primary instructional edifices within the Yujiatou campus of Wuhan University of Technology through the Research Classification Method (RCM), along with the consolidation of insights from experts and academic stakeholders, this study underscores the imperative of enhancing the scientific precision and pertinence of the university’s strategy for preserving historical buildings. By employing both qualitative and quantitative methodologies, this study offers innovative insights into the challenges facing historical building preservation in university settings, therefore propounding effective preservation strategies and offering a roadmap for future endeavors in this domain.

A new approach for heat transfer coefficient determination in triply periodic minimal surface-based heat exchangers

The development of additive manufacturing offers increasing opportunities in heat transfer. A wider range of materials is used in the 3D printing process of heat exchangers based on the Triply Periodic Minimal Surface. Due to the complexity of these structures, it is difficult to precisely determine the values describing the heat transfer process in these devices. One of the parameters describing the heat transfer process in heat exchangers is the heat transfer coefficient. This study describes a new method for determining the heat transfer coefficient in a heat exchanger based on a gyroidal lattice. The proposed new method allows for determining the heat transfer coefficient values without interfering with the internal space of the compact heat exchanger. The developed formula can be used in the indirect method of determining the value of the heat transfer coefficient in two-phase flow with boiling or condensation of the working medium. The thermal tests were carried out in the range of working flow rates 4–24 kg/h; the media temperature was 20 and 50 °C, the heat flux was from 0.1 to 0.4 kW. Tests were conducted for laminar flow in the 20 < Re < 200 range.

The impact of structural analysis of works of fine art on enhancing the creativity of artists and interior designers

This article explores the impact of structural analysis of a work of art on enhancing the creativity of designers and artists. The results of the study showed that consistent adherence to all stages of the artistic and compositional aspect of the analysis of an art object can have a significant impact on increasing creative capabilities in the development of creative thinking, as well as obtaining the necessary instrumental skills for creating various types of internal spaces using objects of fine art. As part of this study, recommendations were also drawn up for the practical use of associative components to create the desired emotional atmosphere in various types of interiors. The results of the study allowed us to propose a methodological approach based on a sequential process, which includes art tasks for students and recommendations for integrating the creative process from the field of art into art education. The proposed approach can also be applied to improve creative skills through analysis in other types of fine arts and will provide an opportunity to replenish and expand the knowledge base in this area.

Attapulgite-intercalated g-C3N4/ZnIn2S4 3D hierarchical Z-scheme heterojunction for boosting photocatalytic hydrogen production

Construction of hierarchical architecture with suitable band alignment for graphitic carbon nitride (g-C3N4) played a pivotal role in enhancing the efficiency of photocatalysts. In this study, a novel attapulgite-intercalated g-C3N4/ZnIn2S4 nanocomposite material (ZIS/CN/ATP, abbreviated as ZCA) was successfully synthesized using the freeze-drying technique, thermal polymerization, and a simple low-temperature hydrothermal method. Attapulgite (ATP) was intercalated into g-C3N4 to effectively regulate its interlayer structure. The results reveal a substantial enlargement of its internal space, thereby facilitating the provision of additional active sites for improved dispersibility of ZnIn2S4. Notably, the optimized photocatalyst, comprising a mass ratio of ATP, g-C3N4, and ZnIn2S4 at 1:1:2.5 respectively, achieves an outstanding hydrogen evolution rate of 3906.15 μmol g−1h−1, without the need for a Pt co-catalyst. This rate surpasses that of pristine g-C3N4 by a factor of 475 and ZnIn2S4 by a factor of 5, representing a significant improvement in performance. This significant enhancement can be primarily attributed to the higher specific surface area, richer active sites, broadened light response range, and efficient interfacial charge transfer channels of the ZCA composite photocatalyst. Furthermore, the Z-scheme photocatalytic mechanism for the sandwich-like layered structure heterojunction was thoroughly investigated using diverse characterization techniques. This work offers new insights for enhancing photocatalytic performance through the expanded utilization of natural minerals, paving the way for future advancements in this field.

Landscape Ecological Structures and Patterns for Green Space Conservation in Forest Monasteries in Northeast Thailand

The green spaces in Wat Pah play an important role in forest conservation in Thailand. This study identified and analyzed the structures and patterns of landscape ecology in Wat Pah Nanachart, Ubon Ratchathani Province, to guide a conceptual framework for green space conservation in forest monasteries. Spatial analysis and modeling using geoinformatics technology were employed to recognize and characterize these landscapes. Information on the green space conservation and management of Wat Pah was also obtained using an in-depth interview and site observation. The results revealed that most of the green space in Wat Pah is forest, characterized by an ecological matrix and a dry evergreen forest. The forest structure can be divided into three canopies, dominated by the Dipterocarpaceae family, which has regenerated into upper and lower canopies. It is an edge matrix and ecological corridor connected to the internal and external green spaces of Wat Pah. It plays an important role in supporting cultural, religious, and aesthetic activities for ordained monks and Buddhists. The spatial landscape model can be divided into three main zones: Thoranisangha, Buddhawas, Sanghawas. Thoranisangha is an open space covered with traditional and artificially planted tree species. It is located in front of the temple and designed for public utilities in the context of managing and conserving the remaining trees. Buddhawas is a semi-open space mostly covered with traditional tree species. It represents Buddhism’s identity and uniqueness and is used for religious ceremonies and dissemination—listening to sermons, meditating, and praying. Meanwhile, Sanghawas is covered with natural forest and contains residences for monks that are designed to be in harmony with the forest ecosystem.

Structural assumption on design of rounded rectangular bellows under pressure

Bellows is a flexible component whose volume can be changed by compression or expansion under pressure. Rounded rectangular type bellows is most applied where the internal space of application is strict. The Expansion Joint Manufacturers Association (EJMA) code is world-recognized code for design by formulas method. However, the calculation formulas of stress and deformation in EJMA code does not consider the shape of corner. Therefore, this study proposed a structural assumption of curved beam model to calculate the stress and deformation for rounded rectangular bellows under pressure load by formula calculation method. A parametric study by means of finite element analysis (FEA) was performed to assess the impact of different structural parameters and the applicable scope was investigated. The experimental and numerical results showed that the proposed method can obtain a suitable precision and safe result when ratio of wave height to corner radius is lower than 35 % and the ratio of length of short side length to corner radius is in range 5–20. This study will enrich existing bellows design code and help industry designers to accelerate the optimization iteration in preliminary design stage instead of FEA.

Dendrimer Platforms for Targeted Doxorubicin Delivery-Physicochemical Properties in Context of Biological Responses.

The unique structure of G4.0 PAMAM dendrimers allows a drug to be enclosed in internal spaces or immobilized on the surface. In the conducted research, the conditions for the formation of the active G4.0 PAMAM complex with doxorubicin hydrochloride (DOX) were optimized. The physicochemical properties of the system were monitored using dynamic light scattering (DLS), circular dichroism (CD), and fluorescence spectroscopy. The Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) method was chosen to determine the preferential conditions for the complex formation. The highest binding efficiency of the drug to the cationic dendrimer was observed under basic conditions when the DOX molecule was deprotonated. The decrease in the zeta potential of the complex confirms that DOX immobilizes through electrostatic interaction with the carrier's surface amine groups. The binding constants were determined from the fluorescence quenching of the DOX molecule in the presence of G4.0 PAMAM. The two-fold way of binding doxorubicin in the structure of dendrimers was visible in the Isothermal calorimetry (ITC) isotherm. Fluorescence spectra and release curves identified the reversible binding of DOX to the nanocarrier. Among the selected cancer cells, the most promising anticancer activity of the G4.0-DOX complex was observed in A375 malignant melanoma cells. Moreover, the preferred intracellular location of the complexes concerning the free drug was found, which is essential from a therapeutic point of view.

The Influence of Climatic and Geographical Conditions on the Volume and Spatial Solutions of Shopping and Entertainment Centers of the Republic of the Congo

The article examines the main climatic and geographic conditions of the Republic of Congo. It was revealed that design in the Republic of Congo is carried out in a warm and humid climate. Based on examples of analyzed construction experience in humid climates, the author made proposals for architectural techniques for organizing the space of shopping and entertainment centers at three hierarchical levels. At the urban planning level, the author proposed organizing the landscape of streets and park areas in such a way as to organize the natural drainage of water from the surface and from the upper balls of the soil. At the level of building formation, techniques are associated with organizing the collection of rainwater through the shaping of the building. The possibilities of protecting retail spaces from rain using canopies are also considered. At the spatial level, it is proposed to drain the swampy area on the territory of the shopping and entertainment center by creating canals. It is proposed to design public areas of shopping centers in such a way that public areas, using their shape, can collect surface water from rain. Further research by the author will be aimed at creating volumetric-spatial methods for organizing shopping center buildings, taking into account the warm, humid climate of the region. Also, further research will be aimed at studying the ventilation of internal open spaces of shopping and entertainment centers. These studies are aimed at creating comfortable urban hygienic conditions within the boundaries of public centers, which should become shopping and entertainment centers.

Ecological Diversity of Micromycetes in Aerial Environments of Russian Libraries

The structure of micromycete communities in the library aerial environment was investigated in 57 Russian cities located in seven federal districts (Northwestern, Central, Southern, Volga, Ural, Siberian, and Far Eastern). A total of 107 micromycete species belonging to 41 genera were isolated and identified. Due to mostly similar conditions, the aerial ecosystem of internal spaces of the library storage facilities was relatively stable, with moderate diversity and high evenness, as was confirmed by the relevant indices: the Shannon index varied from 2.7 to 3.4, the McIntosh diversity index, from 22.7 to 140.8, and the Menhinick index, from 2.1 to 3.0. The Simpson’s dominance index and the Berger–Parker index did not exceed 0.11 and 0.24, respectively. The McIntosh and Pielou’s evenness indices were 0.71–0.78 and 0.79–0.85, respectively. High similarity of the taxonomic structures, independent of climatic conditions of the studied regions, was revealed, as was confirmed by the values of the Stugren–Radulescu and Morisita–Horn coefficients: 0.08‒0.77 and 0.04‒0.47, respectively. The typical members of the studied mycobiota were Aspergillus versicolor (7.5‒14.3), Cladosporium cladosporioides (17.5‒40.5), C. herbarum (0.8‒53.6), and Penicillium aurantiogriseum (6.5‒32.4). Most other species were scarce, with frequencies of occurrence not exceeding 7.1%.

Simulation of Dynamic Path Planning of Symmetrical Trajectory of Mobile Robots Based on Improved A* and Artificial Potential Field Fusion for Natural Resource Exploration

With the rapid development of new-generation artificial intelligence and Internet of Things technology, mobile robot technology has been widely used in various fields. Among them, the autonomous path-planning technology of mobile robots is one of the cores for realizing their autonomous driving and obstacle avoidance. This study conducts an in-depth discussion on the real-time and dynamic obstacle avoidance capabilities of mobile robot path planning. First, we proposed a preprocessing method for obstacles in the grid map, focusing on the closed processing of the internal space of concave obstacles to ensure the feasibility of the path while effectively reducing the number of grid nodes searched by the A* algorithm, thereby improving path search efficiency. Secondly, in order to achieve static global path planning, this study adopts the A algorithm. However, in practice, algorithm A has problems such as a large number of node traversals, low search efficiency, redundant path nodes, and uneven turning angles. To solve these problems, we optimized the A* algorithm, focusing on optimizing the heuristic function and weight coefficient to reduce the number of node traversals and improve search efficiency. In addition, we use the Bezier curve method to smooth the path and remove redundant nodes, thereby reducing the turning angle. Then, in order to achieve dynamic local path planning, this study adopts the artificial potential field method. However, the artificial potential field method has the problems of unreachable target points and local minima. In order to solve these problems, we optimized the repulsion field so that the target point is at the lowest point of the global energy of the gravitational field and the repulsive field and eliminated the local optimal point. Finally, for the path-planning problem of mobile robots in dynamic environments, this study proposes a hybrid path-planning method based on a combination of the improved A* algorithm and the artificial potential field method. In this study, we not only focus on the efficiency of mobile robot path planning and real-time dynamic obstacle avoidance capabilities but also pay special attention to the symmetry of the final path. By introducing symmetry, we can more intuitively judge whether the path is close to the optimal state. Symmetry is an important criterion for us to evaluate the performance of the final path.

Rational design of polymer-based insulating scaffolds for high-capacity lithium metal batteries

Lithium metal is a promising anode material for next-generation high-energy–density secondary batteries. However, the uncontrolled growth of Li dendrites leads to infinite volume expansion and poor cycling stability. Herein, we propose a designable insulating polydopamine (PDA)-coated porous polytetrafluoroethylene (PTFE) scaffold. A porous PTFE (pPTFE) scaffold with micron-sized pores was fabricated, which provided bottom-up Li deposition owing to its insulating nature. Furthermore, the PDA-coated porous PTFE (PDA-pPTFE) scaffold provided internal space for Li growth and homogenized the Li-ion flux with abundant polar functional groups in the PDA, enabling “bottom-up” Li deposition within the scaffold without dendrite growth. This uniquely designed scaffold demonstrated excellent performance in half and symmetric cells with a small voltage hysteresis and dendrite-free Li plating. Moreover, when coupled with high-loading NCM cathodes (∼4 mA h cm−2), the PDA-pPTFE-based full cells exhibited stable cycling and rate performance, even with a low NP ratio of 1.0 at a rate of 1/3C, and exhibited a high energy density of 801 W h L−1. These results indicated the potential of the PDA-pPTFE scaffold as an anode material for highly stable next-generation rechargeable batteries.

The effects of fins number, metal foam, and helical coil on the thermal storage enhancement of the phase change material: An experimental study

Phase change materials (PCMs) are commonly used to store thermal energy as latent heat storage. The low thermal conductivity of PCMs elongates the charging/discharging process time. Using porous media and fins to improve the PCMs’ conductivity are two suggested solutions that have been evaluated in recent research studies. The present work experimentally analyzed the effect of fins usage over a helical tube, the number of fins, and filling the coil internal space with porous media during the energy storage in Paraffin PCM. The thermal conductivity of the PCM is enhanced through the utilization of porous metal foams made of copper, which have a porosity of 0.9 and a pore density of 12 pores per inch. The sole effects of using porous media or fins, in line with their simultaneous effects, and the number of fins on the system’s heat transfer enhancement are investigated. The heat transfer enhancement has been evaluated by examining parameters like the temperature distribution of different points of the heat storage tank, the charging/discharging time, the mean temperature response, the Stefan number, and the obtained discharge power. Results indicate that using either fins or porous media in the storage tank can remarkably improve thermal performance. Furthermore, the best heat transfer enhancement is obtained when using fins and porous media simultaneously. Also, using more fins beside the porous media could further reduce the charge/discharge time. For instance, comparing the cases with only 25 fins, only porous media and the case combined cases reveal respectively about 8.5%, 11%, and 25% decrease in the time of charging process. Also, the best case with 35 fins beside the porous metal foam can reduce the charging/discharging time by about 25%-28%.

Spatial Network Structure and Shift Path Prediction of Ecological Welfare Performance in Chinese Cities—Evidence from 284 Cities

Ecological welfare performance (EWP) serves as a crucial measure for assessing the green development of a region. Exploring the spatial characteristics, network structure, and transfer paths of its specific stages is crucial for grasping an internal space’s EWP and optimizing urban ecological planning. This research employed a two-stage DEA model to assess the EWP of 284 Chinese cities from 2007 to 2022 and decompose it into an ecological–economic transition stage (L1) and an economic welfare transition stage (L2). Second, a social network analysis (SNA) was conducted to describe the EWP sub-stages’ network structure and construction mechanism. Finally, the transmission path process of EWP was revealed through Markov chains. It is found that (1) the overall trend of EWP is rising and then falling, with L2 as the critical constraint; (2) the network structure of the two stages is complex, dominated by industrial structure, urbanization, and healthcare level; and (3) ‘club integration’ constrains the transfer across EWP in the short term. Compared with L2, which has a lower probability of interstate transfer, L1 has a greater likelihood of transfer to a higher level. This paper provides suggestions for the optimal allocation of ecological resources in Chinese cities through the analysis of EWP.

On the universal exceptional structure of world-volume theories in string and M-theory

A universal structure of world-volume theories of 12-BPS branes in string and M-theory in terms of exceptional generalised geometry is observed. Previous constructions are extended in two ways: from internal d-dimensional space to full 11- or 10-dimensional spacetimes, by coupling to the tensor hierarchy gauge fields, and from Ed(d) with d≤6 to E7(7) and E8(8). This is done by a clarification of the role of the tensor hierarchy and its end in the context of brane world-volume theories. The exceptional structure of the gauged σ-model of the Kaluza-Klein monopole is provided as a new example.

Space in Music: what we call ‘space’ in music and what it really is

This article proposes a division of the concept of space in music into four spaces, namely the internal, external, intrinsic and extrinsic spaces. Having reviewed these concepts in texts from numerous authors and composers, we aggregate a variety of concepts into these four main categories of space in music. We also present possible transgressions of the boundaries of these concepts, with the understanding that these transgressions are common practice for contemporary composers. Currently, these practices of transgression tend to be confused because of the lack of a clear definition for the spaces in question.