Types Of Connections Research Articles

Clarifying the definition of common mycorrhizal networks

Abstract Common mycorrhizal networks (CMNs) are an enigmatic feature of soil and mycorrhizal ecology. The current use of the term ‘common mycorrhizal network’ stipulates a direct, continuous physical link between plants formed by the mycelium of mycorrhizal fungal genets. This means that a specific case (involving hyphal continuity) is used to define a much broader phenomenon of hyphae interlinking among roots of different plants. We here embrace a more inclusive definition of the CMN as a network formed by mycorrhizal fungal genets among roots of different plants, irrespective of the type of connection or interaction, and not limited to direct hyphal linkages. Implicitly, this broader version of the term has been used by many researchers already. We propose using the term ‘common mycorrhizal networks with hyphal continuity’ (CMN‐HC) to capture the more specific case of a continuous link via hyphae between the roots of different plants, which is important to study for some (notable carbon and nutrient exchange), but not all functions of a CMN (e.g. transfer of infochemicals or microbes). In addition, and becoming more general than CMN, we introduce the term ‘common fungal network’ (CFN) to include networks of any type of connection formed between different plants by any type of fungus; this includes also non‐mycorrhizal fungi, and indeed a combination of non‐mycorrhizal and mycorrhizal networks. We assert that this new conceptual framework incorporating three hierarchical terms (CMN‐HC, CMN and CFN), ranging from the most specific to the very broad, can usher in a period of new research activity on fungal networks. Read the free Plain Language Summary for this article on the Journal blog.

Performance evaluation of innovative triangular and spherical ribbed headed studs in composite steel beam-concrete slab junction

Composite structures have now become a popular practice in the construction of bridges and RCC structures. Various advancement has been taken in several decades to ensure the composite action between the concrete and steel interface. Shear connectors were developed to ensure this composite action in between the steel and concrete interface of the composite junction. The two types of connections that are most frequently used in composite construction are headed stud shear connectors and channel connectors. The maximum stress concentration of the headed stud shear connector occurs on the bottom of the headed stud shear connector. As a result of the higher stresses at the bottom of the headed stud shear connector the bending height of the headed stud shear connector varies in between 18 to 33% depending upon the grade of concrete. The present study intends to study the effect of geometric variation in headed stud shear connectors according to the requirement of the cross-section. The geometric variations were made with reference to bending height throughout the shank of headed studs. Based on the stress variation the headed stud shear connector is divided into three different zones. For making these variations the headed stud was distributed into three zones. Zone 1 is the headed region of the connector. Zone 3 is the bottom region with maximum shear concentration and zone 2 is the part of shank connecting the zone 3 and zone 1 of the headed stud shear connector. In present study volume reduction is done in the zone 2 region of the headed stud shear connector and volumetric addition is done in the zone 3 region of the headed stud shear connector. Based on the proposed ideology for creating geometric variations, two different studs are proposed namely spherical ribbed headed studs (SRHS) and triangular ribbed headed studs (TRHS) studs. Performance of the proposed SRHS and TRHS shear connectors was evaluated using six experimental specimen and Finite element analysis. Results show that SRHS and TRHS studs have higher shear carrying capacity, ductility and stiffness compared to conventional headed stud shear connectors.

Sustainability and Resiliency Investigation of Grouted Coupler Embedded in RC ABC Bridge Pier at Vehicle Impact

Increased occurrences of natural and man-made dynamic loading caused by high strain rate dynamic impact load have been recently reported. Different statistical results indicate that vehicular impacts occur more frequently compared to the other dynamic loads. However, existing literature primarily focuses on enhancing survivability and determining damage levels specifically in relation to faster bridge construction methods used as an accelerated bridge construction (ABC). In this context, the present study investigates the dynamic behavior of a commonly used connection type in ABC, namely grouted coupler that connects pre-cast elements like bridge piers and foundations. To execute the research, both the static and dynamic performance of grouted couplers embedded in pier foundation subjected to high strain rate loading incurred by high velocity vehicular impact are examined. A representative non-traditional reinforced concrete (RC) bridge pier is selected for the study with the standardized geometry and selected material properties. The use of splice sleeves as coupler materials and specified cross-sectional hollow cast iron cylinders filled with high strength concrete grout is employed for developing Finite Element (FE) modeling, extracting data from published journals. A commercial software, ANSYS, has been utilized to develop FE models to capture post impact respective static and dynamic behaviors, and the simulation results are then compared with the analytical. This also includes determining material performance via FE simulations. By considering dynamic loading, the dynamic impact factor (DIF) has been evaluated for the reinforcing steel bar adjacent and embedded into the coupler. In addition, dynamic simulations, and material modulus in demand to sustain impact are determined. Thus, the research necessitates mesh-independent sensitivity studies to investigate DIF corresponding to the precise outcomes. The findings of this study manifests valuable information that aids to opt for the suitable coupler connections, considering material properties, and adequate post impact execution. Consequently, it will serve as a useful design tool for design offices, structural practitioners, and forensic structural engineers.

Failure analysis and numerical drive structure optimization design of Cr12Mo1V1 electrical connection die

A type of Cr12Mo1V1 electric connection die occured brittle fracture after 200 times of service, and its life was much lower than the design life of the die. In this paper, the 5M1E failure analysis method was adopted, combined with the characteristics of Cr12Mo1V1 cold-work die steel, scanning electron microscopy, direct reading spectrometer, Rockwell hardness tester, metallographic microscope and other means were used to analyze and test the macro fracture morphology, material composition, mechanical properties and microstructure of Cr12Mo1V1 electric connection die. The crimping process of the die was simulated by Deform software. The results show that the material composition is not up to standard, the strength is too low, the internal eutectic carbide is not uniform, the size of carbide exceeds the standard and so on are the root causes of the short life and brittle fracture of the die. In addition, the unreasonable designs of the crack slot and round hole of the die lead to excessive stress concentration in the crimping process of the die, which is too the main reason for the brittle fracture failure of the die. In view of the above factors, the paper puts forward some measures to prolong the life of the electric connection die from the aspects of raw materials, heat treatment, forging process and die structure design.

Measuring social and emotional functioning as a facet of positive youth development among children and adolescents in special education and mental health treatment

AbstractThis study assessed the validity of a set of social and emotional functioning constructs derived from the PYD short form (PYD‐SF) measure within a sample of children and adolescents with one or more mental health diagnoses related to social, emotional, or behavioral challenges. Using repeated measures design, responses to the PYD‐SF and the Social‐emotional assets and resilience scale were collected over two years from 369 students enrolled in special education. Multilevel factor analyses parsed within‐person variability from between‐person differences to understand the internal consistency of the target measures when used with clinical and special education populations. Associations between the social‐emotional constructs from the PYD‐SF and an assessment of social‐emotional assets and resilience were examined. A two‐level confirmatory factor analysis using seven PYD factors and the Social‐Emotional Assets and Resilience Scale indicated a very good model fit; all factor loadings were statistically significant at both levels. Results supported the validity and internal reliability of the social‐emotional constructs from the PYD‐SF measure for assessing the social and emotional competencies of youth with social, emotional, and/or behavioral challenges, but with the caveat that researchers should consider a higher degree of specificity when using it with youth from this population. The broad factors utilized in previous work should be reframed to emphasize separate types of connection. When keeping this revised framing in mind, the social‐emotional constructs of the PYD‐SF measure provide a tool for teachers, parents, and clinicians to use in treatment planning and identifying strategies to support positive development for diverse youth.

Experimental and FE analysis of the behavior of steel column base connections under tension and bending moment

Most design procedures represent the steel base connection by assuming either a perfectly hinged or a fully rigid connection. However, these kinds of connections are, in fact, semi-rigid or flexible and their actual behavior is complicated. Most of the previous studies investigated these base connections experimentally under moments and axial compression only, which is completely different in the case of axial tension and moment. Therefore, experimental and numerical investigations with variable base plate thicknesses and diameters and arrangements of the anchor bolts were carried out to verify the behavior of this kind of base connection under axial tension and moment. Full-scale steel columns with hinged base plate connections were tested under the effect of two simultaneous actions, axial tension force and bending moment. Moreover, Finite Element (FE) models were developed and verified against the experimental results to conduct a parametric study. The investigated parameters were the base plate thickness and anchor bolt diameter and arrangement. The base plate connections under the effect of axial tension with moment instead of axial compression caused reductions in the rotational stiffness up to 99%. In addition, using only two bolts in this type of connection concentrated stresses on the base plate that led to big deformations. The small base plate thickness deformed easily under the effect of tension force which induced big initial gaps between the steel base plate and the Base beam and subsequently decreased the moment resistance and rotational stiffness of the base plate connection. The big elongation of the anchor bolts with small diameters increased the gap between the steel plate and the Base beam.

Non-metricity with boundary terms: 𝖿(𝖰,𝖢) gravity and cosmology

We formulate f(Q,C) gravity and cosmology. Such a construction is based on the symmetric teleparallel geometry, but apart form the non-metricity scalar Q we incorporate in the Lagrangian the boundary term C of its difference from the standard Levi-Civita Ricci scalar R̊. We extract the general metric and affine connection field equations, we apply them at a cosmological framework, and adopting three different types of symmetric teleparallel affine connections we obtain the modified Friedmann equations. As we show, we acquire an effective dark-energy sector of geometrical origin, which can lead to interesting cosmological phenomenology. Additionally, we may obtain an effective interaction between matter and dark energy. Finally, examining a specific model, we show that we can obtain the usual thermal history of the universe, with the sequence of matter and dark-energy epochs, while the effective dark-energy equation-of-state parameter can be quintessence-like, phantom-like, or cross the phantom-divide during evolution.

Analysis, design, and installation of vibration isolation for lightweight helipads

This case study discusses the design and manufacturing steps for the installation of a vibration isolation solution for two lightweight helidecks installed on the rooftop of an existing medical center building. The design stage involved the analysis of the relevant information, involving several specialties, such as Acoustics (for sources of vibration and acoustic performance requirements), Heliport Design[AR1] (for the type of aircraft, MTOW, number of supports, static and dynamic loads), and Structural (for the types of connections to the existing building structure). A collaborative effort between CDM Stravitec and the helideck supplier led the design through a progressive and iterative process where a final design that responded to the strong acoustical requirements and the complex nature of a fully functional and integrated lightweight helideck. Along the design, compromises where made ensure that requirements are met for both acoustic and structural performance. The solution delivered was a prefabricated box, which could easily be installed on site, comprised the necessary components, such as springs and uplift restraints to deal with the challenging aspects of the isolation of lightweight helidecks. The paper also discusses the challenges and best practices encountered during the production and installation of the system.

Universal Sea/Fem Based Method for Estimation of Vibroacoustic Coupling Loss Factors in Realistic Ship Structures

Abstract Despite the fact that there is an existing body of literature addressing the computation of Coupling Loss Factors (CLFs) via the Finite Element Method (FEM), no publications have sufficiently taken into account real structural joints in their approach. Previous research has focused on academic cases of trivial connections, rarely involving more than two steel plates. To enable Statistical Energy Analysis (SEA) on a real ship, a methodology for determining CLFs for non-trivial systems is proposed, considering realistic boundary conditions and irregularities that can occur in marine structures. Based on the method, a library of CLFs is created by selecting the tested connections to enable modelling of about 90% of the acoustic paths on an existing jack-up vessel. Boundary conditions were set by introducing spring elements with a stiffness calibrated to the type of connection and taking the adjacent structure into account. In previous works, CLFs were determined for basic connections of rectangular plates. The lack of scantling variations, ignoring discontinuities and only defining parallel edges in the considered models, lead to the overestimation of energy transmission in real structures. To consider the influence of the above, random deviations from the initial stiffness of the springs at individual edges and point restraints at random points are introduced in this paper.

Ultrasensitive and ultrastretchable metal crack strain sensor based on helical polydimethylsiloxane.

The majority of crack sensors do not offer simultaneously both a significant stretchability and an ultrahigh sensitivity. In this study, we present a straightforward and cost-effective approach to fabricate metal crack sensors that exhibit exceptional performance in terms of ultrahigh sensitivity and ultrahigh stretchability. This is achieved by incorporating a helical structure into the substrate through a modeling process and, subsequently, depositing a thin film of gold onto the polydimethylsiloxane substrate via sputter deposition. The metal thin film is then pre-stretched to generate microcracks. The sensor demonstrates a remarkable stretchability of 300%, an exceptional sensitivity with a maximum gauge factor reaching 107, a rapid response time of 158 ms, minimal hysteresis, and outstanding durability. These impressive attributes are attributed to the deliberate design of geometric structures and careful selection of connection types for the sensing materials, thereby presenting a novel approach to fabricating stretchable and highly sensitive crack-strain sensors. This work offers a universal platform for constructing strain sensors with both high sensitivity and stretchability, showing a far-reaching significance and influence for developing next-generation practically applicable soft electronics.

Mechanical stability of posterior implant-supported monolithic zirconia cantilever on titanium-base abutments. An invitro study.

Investigate survival and technical complications of two-unit posterior implant-supported cantilever made of monolithic zirconia on titanium-base abutments (Zr-TiB) vs. porcelain-fused-to-metal on castable gold abutments (PFM-GA) using two different implant connections, internal butt-joint (IBJ) and internal conical (IC). Forty-eight implants (4.3 mm diameter) were divided into four groups (n = 12) to support 2-unit mandibular premolar cantilevers with two different materials (Zr-TiB vs. PFM-GA) and two connection types (IBJ vs. IC). Tested groups were as follows: (1) IBJ/Zr-TiB; (2) IBJ/PFM-GA; (3) IC/Zr-TiB; and (4) IC/PFM-GA. Specimens were thermomechanical aged (1,200,000 cycles, 98 N, 5-55°C) with occlusal axial load on the pontic. Catastrophic and non-catastrophic events were registered, and removal torque values measured before and after aging. Specimens surviving aging were subjected to loading until failure. Survival, total complication rates, torque loss (%), and bending moments were calculated. From 48 specimens, 38 survived aging. Survival rates significantly varied from 16.7% (IC/PFM-GA) to 100% (IBJ/Zr-TiB; IBJ/PFM-GA; IC/Zr-TiB) (p < .01). Internal conical connection revealed significantly higher torque loss (IC/ZrTiB - 67%) compared to internal butt-joint (IBJ/Zr-TiB - 44%; IBJ/PFM-GA - 46%) (p < .01). Bending moments were higher in internal butt-joint connections than in internal conical (p < .05). Two-unit posterior implant-supported cantilever FDPs replacing mandibular premolars composed of monolithic zirconia on titanium-base abutments demonstrated higher mechanical stability compared to porcelain-fused-to-metal on castable gold abutments in this invitro study. The internal conical connection combined with porcelain-fused-to-metal on gold abutments revealed a high number of failures; therefore, their clinical use may be considered cautiously for this indication.

Progressive collapse analysis on modular steel construction based on a simplified joint model

Modular steel construction (MSC), as a kind of highly prefabricated assembly building, has the advantages of high industrialization, perfect energy saving and great being environmentally friendly. Due to the special characteristics of its detail construction, there is an urgent need to study its progressive collapse resistance performance. Based on the experimental and refined simulating results, a simplified model of inter-module connection was proposed and shown to be accurate enough for capturing the collapse properties of the MSC by comparing with a sub-structure push-down test. Then the collapse responses of a typical four-story, nine-span MSC under different local failure conditions were intensively studied using the proposed model. The MSC survived in the local failure scenarios of the side-columns, the corner-columns or even the mid-modular unit. However, in the scenario of side-modular unit failure, the inter-module connections of all four stories were damaged due to excessive overturning moments, leading to the collapse of the span where the unit fails. Nevertheless, the rest part of MSC still did not collapse. Therefore, it can be concluded that the modular steel construction with inter-module connections by bolts and shear keys has good performance on progressive collapse resistance. Moreover, further research into this type of inter-module connection would be worthwhile.

Visualizing road connectivity under traffic influence: a CiteSpace-based method

ABSTRACT The connectivity of roads under the influence of traffic is determined by the topological connections established by the road network and the transport connections formed by moving vehicles between two roads simultaneously. A thorough examination of this connectivity is crucial for comprehending traffic patterns and providing guidance to address transportation issues such as traffic congestion. However, existing methods ignore the intuitive representation and explanation of this connectivity, limiting the understanding of actual traffic patterns. This study aimed to intuitively visualize the connectivity of roads under the influence of traffic using CiteSpace, a bibliometric tool for analyzing the relationship between literature keywords. Here, the literature was replaced by trajectory, and keywords were replaced by roads. We then presented the connectivity of roads under the influence of traffic in a network, where nodes represented roads and edges represented the topological and transport connections between roads. A case study was conducted in Beijing, demonstrating the dynamic connectivity of roads under the influence of traffic in the visualized network. By comparing the visualized network with the topological road network, we identified three types of road connectivity under the influence of traffic: roads with topological connections but lacking transport connections, roads with transport connections but lacking topological connections, and roads with both topological and transport connections. This finding further revealed the traffic relationship between roads. Additionally, we simultaneously presented the multidimensional traffic characteristics in the visualized network, aiding in predicting traffic states.

Carbon Nanohoops: Multiple Molecular Templates for Exploring Spectroscopic, Electronic, and Thermoelectric Properties.

A combination of density functional theory (DFT) methods and quantum transport theory (QTT) has been used to investigate the spectroscopic, electronic, and thermoelectric properties of carbon nanohoop molecules with different molecular templates. The connectivity type, along with inherent strain, impacts the transport behavior and creates a destructive quantum interference (DQI), which proves itself to be a powerful strategy to enhance the thermoelectric properties of these molecules, making them promising candidates for thermoelectric applications.

Nisu reconfiguration: establishing gender-reversed fan-celebrity fantasies in Chinese society

ABSTRACT Millions of Chinese celebrity fans online increasingly engage in nisu queer fandom—female fans imagining cisgender male celebrities as their girlfriends, wives, etc.—in a male-female gender binary social context. Based on unobtrusive observation and semi-structured interviews among nisu fans of four Chinese actors, this article foregrounds fans’ own perspectives to analyze how their gender awareness shapes their formation of gender-reversed fan-celebrity fantasies and thus their confrontations with mainstream gender ideologies. Findings are presented in two parts. First, nisu fans build three types of fan-celebrity connections: 1) praising actor(s) for performing feminine qualities, 2) gazing at actor(s) from a dominant position, and 3) appreciating actor(s)’ potential gender non-binary charisma. Second, nisu fans understand both how their emerging awareness and expressions of gender beliefs challenge traditional gender norms and how their practices remain intuitive and implicit rather than political. I conclude that nisu fans’ playful gender reconfiguration with fandom ultimately inspires meaningful developments of gender discourses in broader Chinese society.

Spatiotemporal hierarchical transmit neural network for regional-level air-quality prediction

Air pollution has become a growing problem owing to its harmful effects on human health, making accurate air quality prediction an important task to avoid serious environmental impacts. Recently, graph-neural-network-based methods have emerged as promising approaches to modeling the spatial dependencies between adjacent stations. However, they have limitations in capturing the hierarchical temporal features of the time series, which include trends, and periodic components. They also overlook dynamic correlations between stations and multiple types of connections, resulting in generated graphs that lack dynamics. In this paper, we proposed a spatiotemporal hierarchical transmit neural network for the prediction of air quality by extracting long-term periodic features and short-term spatiotemporal dependencies. It incorporates a periodic feature extraction component (PFEC), a scene dynamic graph module (SDGM), a spatiotemporal extraction component (STEC), and a transmit attention (TransATT) component. The PFEC applies discrete Fourier transform and trend decomposition techniques to extract long-term periodic features from the spatiotemporal graph. The SDGM generates dynamic graphs by combining node features of time series with predefined graphs to encode diverse station relationships. The STEC comprises of two convolutional operations and attention mechanisms, enabling the model to capture the short-term spatiotemporal dependencies. TransATT integrates the extracted short-term spatiotemporal dependencies and long-term periodic features, allowing the model to transmit with short- and long-term features. To demonstrate the effectiveness of the proposed model, we conducted experiments on three real-world datasets and found that our approach outperforms state-of-the-art methods.

Advantages of Tissue Level Implants in Case of Alveolar Ridge and Mucosal Atrophy

In the modern market, there is a great variety of dental implants, which differ from each other in design, geometry, connection type, surface treatment technology, etc. However, the most fundamental and main differentiating component between implants is how the implants are inserted into the bone and how it is positioned concerning the soft tissues. Accordingly, they are divided into sunken, i.e., bone level implants and non-sunken, i.e., tissue level implants, in which case the implant-abutment connection, or interface, is located at the gum level. This study shows advantages of tissue level - implants in atrophy of the alveolar ridge, also studies comparison of bone loss in case of bone - level implants and tissue level implants.

Conduits of the Kremlin’s Informational Influence Abroad? How German-Language Alternative Media Outlets Are Connected to Russia’s Ruling Elites

Extant research on alternative media in Western democracies has focused on scrutinizing their content, organization, production, and audiences. However, the extent to which alternative outlets are linked to powerful foreign actors has not yet been analyzed, despite the fact that a plethora of outlets have openly sided with Russia after its full-scale invasion of Ukraine in February 2022, spreading the Kremlin’s propagandistic narratives. To fill this gap, this study adopts a case study approach. It selects Germany as a revelatory case of a key target country of Russia’s foreign influence efforts, raising the question of how and to what extent German-language alternative media outlets are connected to Russia’s ruling elites. Grounded in qualitative analysis of a wide range of documents, this study proposes a categorization that divides the connections into three different types: organizational, media, and personal connections. Subsequently, it is demonstrated that half of the analyzed German-language alternative media outlets maintain at least one of these three types of connections to the Kremlin. These findings contribute to our knowledge of alternative media, as well as Russia’s overt and covert foreign influence operations, the so-called “active measures.” They also highlight the need for more transparency in alternative media landscapes in democratic contexts across the globe.

Grid Integration for Electric Vehicles: A Realistic Strategy for Environmentally Friendly Mobility and Renewable Power

The promotion of electric vehicles (EVs) as sustainable energy sources for transportation is advocated due to global considerations such as energy consumption and environmental challenges. The recent incorporation of renewable energy sources into virtual power plants has greatly enhanced the influence of electric vehicles in the transportation industry. Vehicle grid integration offers a practical and economical method to improve energy sustainability, addressing the requirements of consumers on the user side. The effective utilisation of electric vehicles in stationary applications is highlighted by technological breakthroughs in the energy sector. The continuous advancement in science and industry is confirming the growing efficiency of electric vehicles (EVs) as virtual power plants. Nonetheless, a thorough inquiry is imperative to elucidate the principles, integration, and advancement of virtual power plants in conjunction with electric automobiles, specifically targeting academics and researchers in this field. The examination specifically emphasises the energy generation and storage components used in electric vehicles. In addition, it explores several vehicle–grid integration (VGI) configurations, such as single-stage, two-stage, and hybrid-multi-stage systems. This study also considers the various types of grid connections and the factors related to them. This detailed investigation seeks to offer insights into the various facets of incorporating electric vehicles into virtual power plants. It takes into account technology improvements, energy sustainability, and the practical ramifications for users.

Experimental and numerical investigation of steel–concrete composite beam subjected to contact explosion

The steel–concrete composite beam, consisting of a concrete slab, a steel beam, and shear connectors, is extensively utilized in bridge engineering due to its effective utilization of material properties and convenient construction. Considering the significant impact of explosive incidents on bridge safety, and the limited experimental research on blast performance of composite beams, this study tested three small-scale SC composite beams arranged with commonly used shear connectors, including studs, PBL ribs, and combination connectors, under contact explosion with 200 g of TNT. Finite element (FE) models, validated by the experimental data, were established to conduct damage analysis to understand the damage mode and characteristics of SC composite beams. The results showed that the SC composite beams exhibit a localized damage pattern concentrated in the mid-span of the beams under contact explosions. The concrete spalling on the bottom surfaces could be divided into two parts by the top flange of the steel beam. The concrete slab, which absorbs more than 94 % of the total internal energy of the SC composite beams, plays the most important role in reducing the damage to the beams under contact explosion. In some aspects, the type of shear connectors influences the crack pattern, concrete spalling degree, the deformation of the steel beam, and the difference in acceleration response between the concrete slab and steel beam, but on the whole, it has a limited effect on the damage mode and degree of SC composite beams subjected to contact explosion.