Meta Structures Research Articles

Multiscale Porous Architecture Consisting of Graphene Aerogels and Metastructures Enabling Robust Thermal and Mechanical Functionalities of Phase Change Materials

AbstractPassive thermal energy storage systems using phase change materials (PCMs) are promising for resolving temporal‐spatial overheating issues from small‐ to large‐scale platforms, yet their poor shape stability due to solid–liquid transition incurs PCM leakage and weak resistance against mechanical disturbance, limiting practical applications. While foam‐stable templates for PCMs have shown complement, they reveal massive leakage and collapse of liquefied PCMs under external loads or impacts. Herein, a multiscale porous architecture consisting of graphene aerogels (GAs) and meta structures enabling robust thermal‐mechanical functionalities of PCMs (3D‐MPGA) toward sustainable phase change thermal energy storage composites is reported. 3D‐printed mechanical metamaterials employing octet‐truss cells provide supportive strength and directionally‐assisted leakage reduction, while GAs serve as porous templates with surface‐interfacial contacts, thereby fixing paraffin wax as PCM inside their nano/micropores. The 3D‐MPGA shows intrinsic thermal characteristics of bulk PCMs, and improved thermal‐mechanical‐chemical stability, confirmed by long‐term heating‐cooling cycle tests over 10 h. Moreover, it exhibits highly reinforced strength (200–5000%) within a low density across ambient and melting temperatures, and maintains original shapes in the liquefied PCMs without severe leakage, against external loads. This work inspires rational strategies for advancing robust thermal‐mechanical functionalities for PCM‐based thermal energy storage systems.

Collecting the energy of the electromagnetic fields over the infrared band based on the metastructures

Predicated on the surface plasmon polariton, this study proposes the metastructures (MSs) constructed from copper and general dielectric films. The MSs are specifically designed to gather electromagnetic (EM) wave energy over the infrared band on the surface. Evidence illustrates that, when EM waves impinge the surface of the MSs, there is a significant surge in surface energy density, confirmed to be a staggering 2022.90 times higher than that of the ancillary EM waves. This substantial multiplication owes its genesis to the enhanced impedance matching between the MSs and free space. Furthermore, the MSs demonstrate the ability to accurately determine refractive indices ranging from 1 to 1.39, as well as measure hydrogen density spanning from 0 g/cm3 to 0.13 g/cm3. This is achieved through the assessment of absorption peak locations, the intensity of absorption, and the field enhancement factor (FEF) at the peak. The subtle absorption peak experiences a shift in alignment with the changes in refractive indices. The relationship between the peak position and the refractive index demonstrates an exceptional degree of linearity, achieving the R2 value of 1. The values of Q, Sλc, and FOM average at 1437, 1.24 μm·RIU−1, and 682.38 RIU−1, respectively. The study also examines the effects of the incident angle of the external electromagnetic (EM) field and the number of dielectric films. Within a limited range of incident angles, an increase in the angle results in a shift of the absorption peak towards shorter wavelengths. The number of films plays a role in modifying the absorption intensity and the field enhancement factor (FEF) at the peaks. The proposed MSs offer improved energy harvesting capabilities from the surface EM fields. They can also be employed for refractive index detection. Besides, the field enhancement phenomenon provides valuable insights into the adsorption and storage of the hydrogen.

Machine learning assisted intelligent design of meta structures: a review

In recent years, the rapid development of machine learning (ML) based on data-driven or environment interaction has injected new vitality into the field of meta-structure design. As a supplement to the traditional analysis methods based on physical formulas and rules, the involvement of ML has greatly accelerated the pace of performance exploration and optimization for meta-structures. In this review, we focus on the latest progress of ML in acoustic, elastic, and mechanical meta-structures from the aspects of band structures, wave propagation characteristics, and static characteristics. We finally summarize and envisage some potential research directions of ML in the field of meta-structures.

Multifunctional and tunable ultra-broadband linear to circle polarization converter based on VO2-integrated material

Considering that the metastructures (MSs) previously proposed usually perform in a single state, herein, a multifunctional and tunable ultra-broadband linear to circle (LTC) polarization converter based on phase transition material vanadium dioxide ( V O 2 ) is proposed in the terahertz (THz) region. By manipulating the temperature, the function of the LTC polarization conversion (PC) can be conveniently switched between transmission and reflection states. When the environment temperature is low, V O 2 presents the insulating state, and the MS can achieve ultra-wideband LTC PC from 0.57–0.83 THz with a relative bandwidth (RB) of 37.3%. When the temperature exceeds 68°C, LTC PC with the frequency bandwidth of 0.83–1.20 THz and 0.83–1.17 THz can be obtained in a reflection state when electromagnetic waves propagate forward and backward, whose RBs are 36.4% and 34.0%, respectively. Meanwhile, a broadband linear to linear (LTL) PC can also be realized in the range of 1.19–1.41 THz for the forward incident wave and 1.16–1.37 THz for the backward incident wave. The designed MS offers an effective method to realize four different functions and has tremendous potential value in realizing THz modulation devices, electromagnetic cloaking, and communication systems.

Design and Optimization of Lightweight Lithium-Ion Battery Protector with 3D Auxetic Meta Structures

This research study involves designing and optimizing a sandwich structure based on an auxetic structure to protect the pouch battery system for electric vehicles undergoing ground impact load. The core of the sandwich structure is filled with the auxetic structure that has gone through optimization to maximize the specific energy absorbed. Its performance is analyzed with the non-linear finite element method. Five geometrical variables of the auxetic structures are analyzed using the analysis of variance and optimized using Taguchi’s method. The optimum control variables are double-U hierarchal (DUH), the cross-section’s thickness = 2 mm, the length of the cell = 10 mm, the width of the cell = 17 mm, and the bending height = 3 mm. The optimized geometries are then arranged into three different sandwich structure configurations. The core is filled with optimized DUH cells that have been enlarged to 200% in length, arranged in 11 × 11 × 1 cells, resulting in a total dimension and mass of 189 × 189 × 12 mm and 0.75 Kg. The optimized sandwich structure shows that the pouch battery cells can be protected very well from ground impact load with a maximum deformation of 1.92 mm, below the deformation threshold for battery failure.

Short Text Topic Learning Using Heterogeneous Information Network

With the explosive growth of short texts on users' preferences, learning discriminative and coherent latent topics from short texts is a critical work, since many practical applications require semantic understandings that short texts convey explicitly and implicitly. However, existing short text topic learning methods face the challenge of fully capturing semantically related co-occurrence phrases. Therefore, this paper proposes a novel Heterogeneous Information Network-based Short Text Topic learning approach (HIN-ShoTT) in terms of parts of speech, without depending on any auxiliary information. Specifically, HIN-ShoTT can be decomposed into three phases: i) seeking semantic relations among words, where HIN-ShoTT models multiple semantic relations among words based on a Heterogeneous Information Network (HIN) in terms of parts of speech; ii) extracting co-occurrence phrases and filtering noises, where HIN-ShoTT defines parts-of-speech meta structures to guide co-occurrence phrase extraction and a self-adapting threshold filtering module is proposed for discarding noises; and iii) inferring topics, where HIN-ShoTT models the generative process of co-occurrence phrases to make topic learning effective with the abundant corpus-level information. Our experimental results on three real-world datasets not only show that HIN-ShoTT performs well, but also demonstrate that it is feasible to incorporate HIN into short text topic learning for accuracy improvement.

Testing Structuration Theory in E-Government System Assimilation: Mediating Role of Pakistani Cotton Ginners’ Absorption Capacity

Electronic Government (e-government) is a significant and vital application of the information and communication technologies (ICTs) to enable functional relations and communication with key government stakeholders. Governments have launched E-Government system for the basic objective of delivery and transfer of electronic information as well as services to their targeted citizens and for enhancing interaction with businesses and commerce. Therefore, assimilation and integration of E-Government systems in organizations is a strategic need. However, existing literature on E-Government system assimilation and meta-structures of organization (signification, domination, and legitimization) is limited. Therefore, in this paper, based upon structuration theory, we have developed a theoretical model with the aim to investigate the effect of organizational meta-structures of signification, domination, and legitimization on E-Government system assimilation with mediating effect of E-government absorption capacity. To test the proposed model, data collected from 292 ginning firms listed in the Pakistan Cotton Ginning Association (PCGA). The results confirm the direct relation between organizational meta structures and E-Government system assimilation and also support the mediating relationship of E-Government absorption capacity between the E-Government system assimilation and organizational meta structures. Moreover, the theoretical and managerial implications along with limitations and direction for future research also have been discussed in this study.

Weighted meta paths and networking embedding for patent technology trade recommendations among subjects

Most patent technology recommendations are based on link prediction of a homogeneous trade network and multiple-attribute matching. We constructed a heterogeneous information network (HIN) with four types of nodes and seven types of relations; designed a heterogeneous relation traversal algorithm based on the meta paths and meta structures inspired by the depth first search (DFS) strategy; obtained subject-relation sequences; and then calculated the weight of each meta path and meta structure through logistic regression. Using the relation sequence corpus of the weighted meta paths and meta structures among subjects, the patent technology trade recommendation model based on network embedding (PSR-vec) was proposed. The model was trained by using the Skip-gram method to obtain a vector-space representation for all subjects. Finally, the recommendation target was achieved by measuring the cosine similarity of the subject vectors. Through empirical research on the electronic information patent data, we observed that the PSR-vec model with weighted meta paths and meta structures was more precise than that with a single meta path or meta structure, which indicated that the patent technology trade was influenced by multiple factors. Second, the PSR-vec model combining weighted meta paths and meta structures was more precise than the unweighted model, which reflected more differences in multiple factors affecting trade. Third, compared to Deep Walk, Node2vec, Metapath2vec, and GraphSAGE methods, the PSR-vec model had a higher precision of up to 80%. Eventually, the recommendation subjects of PSR-vec included the holding relation, the supply relation, and the loose relation, which increased the diversity of the recommendation results. Our research thus provided a decision-making method for effective docking among patent technology trade subjects.

Theorizing regulatory governance within its ecology: the structure of management in an age of globalization

ABSTRACTThis article examines regulatory governance (‘RG’) within its own ecology. It considers RG as an ideology of governance, as its own set of techniques to that end, and as a methodology and psychology of the relations of regulatory organisms to one another and to their context. The object is first to chart the structures and modalities of this ecology, and second to understand the properties that makes RG both coherent (singularly as the method of regulating a field, as the framework for the use of RG techniques, and as an ideology of governance), and structural (as a means of structuring regulation as an exercise of ordering power. After a brief introduction, the article introduces the regulatory context through a close reading of the operation of global garment supply chains in Bangladesh, examining RG in action within the ecology of global production. It then theorizes the meta structures of RG within this ecology as a mechanics for governance within institutions, and as an ideology for ordering systems of governance among institutions.

Tailoring the flow of acoustic waves by architectured metamaterials

Today, sound is an indispensable component in numerous industrial and consumer products, such as musical instruments, cars, building technology, medical diagnostics, and many others. Acoustic characteristics are among their most important properties, greatly influencing their function and our society at large. Recent development of acoustic metamaterials opens a door to an unprecedented large design space for acoustic properties such as negative bulk modulus, negative density, and refractive index. These novel concept expands paves the way for the design of a new class of acoustic materials and devices with great promise for diverse applications, such as broadband noise insulation, sub-wavelength imaging and acoustic cloak from sonar detection. In this invited talk, I will present our development of advanced design and micro/nanofabrication techniques, to enable exploration architectured meta structures for acoustic waves. These structures show promise on focusing and rerouting ultrasound through broadband metamaterials. As example, our study on the sound absorption of thin composite aerogel foams using a bimodal porous structure predicts a possible route to perfect thin film absorber by increasing the amount of epoxy resin. In a second case, bifunctional acoustic lens can be implemented in practice with subwavelength unit cells exhibiting effective anisotropic parameters. Lastly I will report our study on a prototype hydraulic hydrogel actuators with excellent optical and sonic transparency.

Sapiens Mitochondrial DNA Genome Circular Long Range Numerical Meta Structures are Highly Correlated with Cancers and Genetic Diseases mtDNA Mutations

Using the circular nature of the 16k base-pairs human mtDNA genome, we are looking for hypothetical proportions between the C+A and T+G bases. Remarkable proportions are thus discovered, the length of which may be much greater than the length of the genome. We then analyze the impact of evolution on these “numerical resonances” by comparing the referenced mtDNAs of Sapiens, Neanderthal and Denisova. Then, by analyzing 250 characteristic mutations associated with various pathologies, we establish a very strong formal causal correlation between these numerical meta structures and these referenced mutations. To summarize, we should think then research on the following situation: (a) Inputs: 250 cases of mtDNA mutations1 associated with various human diseases. (b) An operator: The exhaustive search for mtDNA genome “Fibonacci resonances” associated with these mutations. (c) A “binary” output: a common behavior of the mtDNA genome resulting from these 250 mutations disorders.

Emerging meta-organisations and adaptation to global climate change: Evidence from implementing adaptation in Nepal, Pakistan and Ghana

As developing countries move from policy to implementing adaptation to climate change, formal operational structures are emerging that exceed the expertise of any one actor. We refer to these arrangements as ‘meta-organisations’ that comprise many autonomous component organisations tackling adaptation. The meta-organisations set standards, define purposes, and specify appropriate means-ends criteria for delivering adaptation. Using empirical data from the three cases, Nepal, Pakistan and Ghana, the study identifies and analyses six attributes of the meta and component organisational structures. We argue that organisational structures are crucial to understanding adaptation, specifying policy and implementation. Our analysis demonstrates that while each country promotes similar objectives, the emerging structures are quite distinct, shaped by country-specific attributes and issues that lead to different outcomes. Nepal’s priority for a formal process has come at the cost of delayed implementation. Pakistan’s devolved approach lacks legitimacy to scale up the process nationally. Ghana’s use of existing decentralised structures and budgets relegates adaptation below other development priorities. These divergent structures arise from the different needs for legitimacy and accountability, and the relative priority attached to adaptation against other needs.

Donor-Activated Lithiation and Sodiation of Trifluoromethylbenzene: Structural, Spectroscopic, and Theoretical Insights

Aiming to shed new light on the stability and constitution of the organometallic intermediates involved in direct ortho-metalation processes, using trifluoromethylbenzene (1) as a case study, this paper investigates the deprotonation of 1 using group 1 alkyl bases tBuLi and nBuNa in the presence of the Lewis donors TMEDA (N,N,N′,N′-tetramethylethylenediamine), THF, and PMDETA (N,N,N′,N″,N″-pentamethyldiethylenetriamine). A systematic and comprehensive study combining structural, spectroscopic, and theoretical studies reveals that these donors strongly influence the final outcome of the reactions, not only by activating the alkali-metal bases and facilitating deprotonation of 1 but also by tuning the regioselectivity of the reaction. Thus, while using tBuLi/TMEDA, ortho-metalation of 1 is preferred, switching to THF gives a complex mixture of products with the meta-regioisomer being the major species crystallizing from hexane solution. This donor effect is significantly reduced when nBuNa is employed, as ortho-regioselectivity is observed almost exclusively using THF, TMEDA, or PMDETA. DFT calculations computing the relative energies of the ortho-, meta-, and para-regioisomers obtained from these metalating systems have also been carried out. Reinforcing the experimental findings, these theoretical studies show that although in all cases the product of ortho-metalation is the most thermodynamically preferred, the energy difference between the three possible modeled regioisomers is much larger for the Na systems than for the Li ones. The structures of key reaction intermediates [(TMEDA)·Li(C6H4-CF3)]2 (2), [(TMEDA)·Na(C6H4-CF3)]2 (3), and [(PMDETA)·Na(C6H4-CF3)]2 (4) have been elucidated by X-ray crystallographic studies. All compounds exhibit a similar dimeric arrangement with a four-atom core constituting a {MCMC} ring. Interestingly for Na derivatives 3 and 4 unusual Na···F dative interactions are found, which appear to contribute to the overall stability of these compounds, therefore favoring ortho-metalation of 1, as the meta or para structures do not contain these additional interactions.

Microstructure and micro-Raman studies of nitridation and structure transition of gallium oxide nanowires

Abstract Here we present a detailed study on nitridation and structure transition in monoclinic gallium oxide (β-Ga2O3) nanowires grown on Si substrates with chemical vapor phase epitaxy. The nanowires were systematically nitridated at different temperatures. Their morphologies and microstructures were precisely characterized using field-emission scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and confocal micro-Raman spectroscopy. It is found that heat treatment of Ga2O3 nanowires in the gas of ammonia results in rich substructures including the Ga2O3 phase, the crystalline GaN phase, and other meta structures. The identification of these structures helps to understand some interesting phenomena observed in nanostructures, such as the microstructural origin of the unknown Raman lines in GaN nanowires.

ChemInform Abstract: Crystal Structures of o‐, m‐, and p‐Nitrophenylferrocenes and Their Relevance to Other Sterically Crowded Phenylferrocenes

The crystal structures of the nitrophenylferrocenes [Fe(η-C5H5)(η-C5H4R)][R =o-(1), m-(2), or p-O2NC6H4(3)] have been determined. All three structures consist of discrete molecules with the iron atom η5-bonded to both cyclopentadienyl rings with bond lengths in the range 1.997(9)–2.120(10)A. The steric constraints of the nitro group lead to different conformations in the three structures. Thus in the ortho structure, the o-nitro group intersects the phenyl ring at angle (Θ′) of 42.3(1)° and the phenyl ring intersects the cyclopentadienyl (cp) ring at an angle (Θ) of 43.6(1)°. Corresponding angles in the less crowded meta and para structures are 10.3(1), 17.4(1)(meta) and 2.9(1), 12.5(1)°(para) respectively. These structures are discussed in conjunction with that of 2,2′,5,5′-tetramethyl-1,1′-bis(2″,4″,6″-trimethylphenyl)ferrocene, (4), and other ortho-substituted phenylferrocenes. Iron-57 Mossbauer and 13C n.m.r. data for (4) are presented and discussed. The 13C data have been used in an estimation of Θ for a number of ortho-substituted phenylferrocenes. A critical survey of known structures of ferrocene derivatives is also presented.

Crystal structures of o-, m,- and p-nitrophenylferrocenes and their relevance to other sterically crowded phenylferrocenes

The crystal structures of the nitrophenylferrocenes [Fe(η-C5H5)(η-C5H4R)][R =o-(1), m-(2), or p-O2NC6H4(3)] have been determined. All three structures consist of discrete molecules with the iron atom η5-bonded to both cyclopentadienyl rings with bond lengths in the range 1.997(9)–2.120(10)A. The steric constraints of the nitro group lead to different conformations in the three structures. Thus in the ortho structure, the o-nitro group intersects the phenyl ring at angle (Θ′) of 42.3(1)° and the phenyl ring intersects the cyclopentadienyl (cp) ring at an angle (Θ) of 43.6(1)°. Corresponding angles in the less crowded meta and para structures are 10.3(1), 17.4(1)(meta) and 2.9(1), 12.5(1)°(para) respectively. These structures are discussed in conjunction with that of 2,2′,5,5′-tetramethyl-1,1′-bis(2″,4″,6″-trimethylphenyl)ferrocene, (4), and other ortho-substituted phenylferrocenes. Iron-57 Mossbauer and 13C n.m.r. data for (4) are presented and discussed. The 13C data have been used in an estimation of Θ for a number of ortho-substituted phenylferrocenes. A critical survey of known structures of ferrocene derivatives is also presented.

The computer simulation of meta structures

This paper outlines the results of a research project dealing with a dynamic prediction system for space oriented architecture in Meta Structures using interactive computer graphics techniques. Meta Structures in architecture are variable, space-enclosing, support systems that allow maximum dimensional changes with minimum effort and/or adjustment. Examples of Meta Structures range from the simple umbrella to the complex, variable support system of Skylab II. The use of real time computer graphics has been investigated to improve the design of structures which until now could only be vizualised through expensive scaled models. This investigation has initiated the development of a computing model which allows the user to interactively define a Meta Structure via linguistic and analog control and to simulate the real time motion of structures that are considered to be part of the indeterminate set. The user may deploy a designed structure in real time observing the transformations on the Vector General 3DR graphics display which is controlled by a PDP 11/45 using the GRASS language developed by Dr Thomas A. Defanti at the University of Illinois, Chicago Circle. This observation can be compared to watching an automobile convertible top being automatically deployed from its stored position to its unfolded position.

Conversion of neobarenes into anions of neodicarbaundecaboranes(13)

1. Anions of neodicarbaundecaboranes(13) are formed smoothly by heating neobarenes with caustic potash in butyl and amyl alcohols, methyl- and ethylcellosolves, and ethylene glycol. 2. On the basis of the oxidative cleavage of phenylneodicarbaundecaborane(13) and phenyldicarbaundecaborane(13), which leads to identical products (tolune, ethylbenzene, styrene, phenylacetylene, benzaldehyde, and acetophenone), the idea of a mutual rearrangement of the ortho and meta structures in the intermediate products of the oxidation of derivatives of neodicarbaundecaborane(13) and dicarbaundeca-borane(13) has been proposed.