Part Of Structure Research Articles

On Selecting Indicators for SEM Models: Trade-Offs Among Variable Type, Quantity, and Quality

To study the dynamics among latent variables, researchers often use structural equation modeling (SEM). The real interest of SEM is often in the structural part, which explains the relationships among the latent variables. The indicators are peripheral; they exist because it is impossible to obtain the latent variables’ scores. Perhaps because the indicators are peripheral in developing substantive theories, how to choose indicators for SEM has received little attention in the literature. The attention has been largely drawn to model estimation and evaluation given a set of indicators, but the importance of indicators for the quality of model estimation has been overlooked. In this paper, we study the trade-offs among the variable types, quantity, and quality of indicators with respect to the quality of estimating structural-level model parameters. Better selections of indicators can substantially improve estimation quality without increasing the sample size. Using many lower-loading indicators is not necessarily inadvisable.

L2 German Word Order Preferences by Immigrant L1 Korean Speakers

Abstract This study examines the L2 German verb placement preferences in 58 Korean immigrant workers in Germany. The verb placement preferences are compared to predictions of Organic Grammar (Vainikka and Young-Scholten, 2011). Assuming an incremental, bottom-up morphosyntactic development, the theory predicts the possibility that L2 acquirers develop only partial clausal structures. Organic Grammar further proposes a two-tree approach of morphosyntactic development and predicts that main clauses with verb-second order (V2) are acquired before subordinate clauses with verb-final order (OV). To test these predictions, participants completed two production tasks. Results show a mixed picture. Some participants’ L2 clausal structure seems to have developed only partially, supporting the incremental approach. Regarding the predicted order of acquisition, however, some participants who showed robust use of targetlike subordination with OV, struggled with V2, preferring V3 instead. This suggests the need for a revision of the two-tree approach to incorporate the V3 preference.

Assessment on wire-arc additive manufactured high strength low alloy steel cylindrical component

Large structural parts are widely manufactured through wire-arc additive manufacturing (WAAM) due to its high deposition rate, flexibility, and low cost. There are a variety of industries where high strength low alloy (HSLA) steel is used, including naval, tool and die manufacturing, construction, and offshore structures. The present article examines the mechanical properties and microstructural evolution of a developed HSLA component. The microstructural analysis was done in the component’s top (TR) and bottom (BR) regions. It reveals almost similar microstructural constituents but with more polygonal ferrite in the TR and bainitic structure in the bottom, with acicular ferrite in both regions. The inclusions in both regions were characterized using energy-dispersive X-ray spectroscopy. This demonstrates that manganese (Mn), as a strong deoxidizer, reacts with oxygen and dissolves entirely within the inclusion, forming a Mn depletion zone. Additionally, grain coarsening was observed in the building direction. The average grain size in the TR and BR was 13.12 μm and 6.54 μm, respectively. Within the regions considered, only 2.47%, 4.06%, and 0.65% variations were observed between yield strength, ultimate tensile strength, and elongation to fracture.

Focal adhesions, reticular adhesions, flat clathrin lattices: What divides them, what unites them?

The majority of cells within multicellular organisms requires anchorage to their surroundings in the form of cell-cell or cell-matrix adhesions. In regards to cell-matrix adhesions the transmembrane receptors of the integrin family have long been recognized as the central scaffold around which these adhesion complexes are built. Via their extracellular domains integrins bind extracellular matrix ligands while their intracellular tails interact with a plethora of proteins that link integrin-based adhesions to the cytoskeleton and turn them also into important signaling platforms. Depending on the specific intracellular interactome of the integrins, different types of integrin adhesion complexes have been classified. The best studied ones are the focal adhesions in which integrins become firmly linked to contractile actomyosin fibers allowing for force transduction. But integrins also form an integral part of adhesion structures that lack the strong actomyosin link and are enriched in endocytic proteins. These have been named reticular adhesions, flat clathrin lattices or clathrin plaques. Initially, the different types of integrin adhesion complexes have been viewed as discrete entities with their own separate life cycles. However, in the past years it has become more and more apparent how closely intertwined they are. In fact, it was shown that they can trigger each other´s biogenesis or can even directly convert into each other. Here, we will describe similarities as well as differences between integrin adhesion complexes focusing on the versatile αvß5 integrins and discuss the recently discovered close links and interconversion modes between the different αvß5 integrin adhesion types.

Pathology of reinforced concrete constructions seismic rehabilitation assistance

In severe stress, reinforced concrete structures are generally classified into three categories: red, where significant damage has occurred to the load-bearing structure; orange, where damage to the structural part is considered slight; and yellow, where the structural part is sound. The last two classes are necessarily exposed to several remedial techniques such as rehabilitation, repair, reinforcement, etc. Unfortunately, these techniques are not well detailed in all seismic building codes and regulations. Classroom buildings must be upgraded to increase their lifespan, make them more functional, and comply with new seismic building regulations. In an earthquake, structural elements are damaged (cracks, concrete bursts, steel plasticization, breakage, etc.) due to faulty execution and architectural design, which are highly detrimental to the building's response to an earthquake. For this reason, the present work aims to test a set of cases under severe loading and compare them with the healthy state to get an idea of the remediation operation. The remediation operation will be based on the diagnosis and reporting of the results.

Extended Dummy Node Rule for analysis and characterization of pin-jointed periodic cellular materials: An approach based on Bloch-wave method

Micro-truss lattice materials are a class of hybrid periodic cellular solids that consist of a combination of solids and voids. The material is partitioned into cells structured in a given cell topology tessellated to form an almost unbounded micro-truss framework. The Bloch-wave method is one technique that can describe the propagation of a wave function over a periodic infinite lattice. It demonstrated the effectiveness of modeling the static and dynamic responses of lattices of various topologies. However, the Bloch-wave method presents limitations when applied to unit cell topologies whose structural elements extend across their envelopes to adjacent unit cells, as a given unit cell may not contain the full nodal parameters and periodicity information necessary to describe the kinematic and static wave propagations across the periodic lattice. The first part of this paper presents the Dummy Node Rule (DNR), which overcomes this limitation. The rule introduces dummy nodes at the intersection points between cell envelopes and elements extending between the adjacent unit cells, which are initially treated as part of the finite unit cell structure. Then, the rule establishes mathematical relationships between the static and kinematic wave functions propagating across dummy nodes and those propagating across the connected cell elements. The second part of the paper describes DNR for specific applications such as (a) the development of static and kinematic systems of the unit cell finite structure, which aids in the determinacy analysis of periodic lattice structures, and (b) the development of the Cauchy–Born kinematic boundary condition that is used to homogenize the kinematic response of the infinite periodic structure to an assumed macroscopic strain field, which in turn, forms the effective properties of the lattice material. Furthermore, the last part of the paper shows examples where the scheme is applied for the stiffness characterization of selected lattice topologies.

Hubungan Kecerdasan Linguistik dengan Kemampuan Semantik Anak Gangguan Neurodevelopmental di Sekolah Luar Biasa Kota Surakarta

Background: Neurodevelopmental disorders are associated with disorders that lead to brain development characterized by an inability to reach normal limits of cognitive, emotional and motor development. This is also characterized by a delay in the language development process. Cognitive-linguistic is the ability to use language, both written and spoken, in various forms to express ideas. One of them is semantic skill. Semantics is the part of language structure that is related to the meaning of expressions and the meaning structure of speech. Objectives: This study aims to determine the relationship between cognitive-linguistic and semantic skill in children with neurodevelopmental disorders in special schools in Surakarta City. Methods: This research is a quantitative research with a descriptive correlational research design. The sampling technique used is purposive sampling with 60 respondents. The research instrument uses a linguistic intelligence test (Cognitive Linguistic Evaluation) and a semantic ability questionnaire. The statistical test used in this study is Kendall's Tau. Results: The results of the Kendall's Tau test showed a ρ value of 0.000 (ρ < 0.05) and a correlation strength of 0.417. This means that there is a relationship between cognitive-linguistic and semantic skill, with a moderate correlation strength and a positive correlation direction. This means that the higher the child's cognitive-linguistic, the higher their semantic skill. Conclusion: There is a relationship between cognitive-linguistic and semantic skill in children with neurodevelopmental disorders in special schools in Surakarta City. Keywords: Cognitive-Linguistic, Semantic, Neurodevelopmental Disorders

Sensory experience beyond vision: Shah Tahmasb’s sixteenth-century garden in Qazvin

In this article, we examine the grand compendium of verses composed by Abdi Beg Shirazi (1515–80/1) in the middle decades of the sixteenth century, which portrays the royal Sa’ādat-Ābād complex of the second Safavid ruler Shah Tahmasb (1524–76). Through careful reading and interpretation of these poems, both individually and as part of the larger structure of the compendium, we revisit the symbolism and mode of perception of gardens in the early-modern Persianate world. Contributing to the scholarship on the sensory turn, we argue that Shirazi’s portrayal of royal gardens as a terrestrial paradise relied on senses and experiences rather than on the formal properties of these gardens. The poet presented the garden as a set of cognitive episodes rather than visual frames. As such, Abdi Beg Shirazi’s text offers a compelling insight into the perception and reception of gardens in the early-modern Persianate world that helps expand the scope of current scholarship on the subject.

On the use of modal works of cutting forces to optimize machining conditions in the presence of vibrations

The use of Virtual Machining models may be a valuable approach in the designing stage of a machining operation as long as the models are sufficiently accurate. When vibration risks are suspected, stability analysis approaches to predict regenerative chatter phenomena are generally used. However, although these approaches, when applicable, allow efficient numerical optimization of the process around an operating point, they often require other strong assumptions such as neglecting transient phenomena or oversimplifying kinematics. On the other hand, time domain approaches with detailed matter removal modelling allow to monitor the continuous evolution of cutting conditions and represent various phenomena that the models can reproduce (regenerative chatter, forced vibrations, non-linear behaviours). The amount of data produced is, however, considerable and often costly to analyse. It may therefore be interesting to deduce, from these data, scalar indicators allowing easier and more relevant analysis of the simulation results.In this work, the modal work of the cutting forces upon the workpiece vibratory displacements is proposed as an indicator to discriminate different tool paths. A one degree of freedom theoretical problem and a face milling operation on extruded aluminum profiles extracted from automotive structural part are used to explain and show the relevance of such indicator.

Molecular analysis of the 2022 mpox outbreak and antiviral activity of dihydroorotate dehydrogenase inhibitors against orthopoxviruses

Monkeypox virus (MPXV) has caused a large pandemic outbreak in 2022 with more than 90.000 confirmed cases and 181 deaths. Notably, signs of microevolution and host adaption have been observed. Here, we demonstrate that viral genomes from Franconia, Bavaria acquired different mutations. Three isolates obtained from diagnostic samples, submitted from suspected Mpox cases, show differences in their replication capacities. One MPXV isolate which shows the fastest replication kinetics and higher viral loads, possesses a unique non-synonymous mutation (D616L) in the A11L protein (gene OPG136), which encodes for a protein that is part of a major viral core structure. In regard to pandemic preparedness and future outbreaks, we analyzed the antiviral activity of dihydroorotate dehydrogenase (DHODH) inhibitors, and show that they are active against MPXV, vaccinia virus (VACV), and cowpox virus (CPXV) and therefore likely against orthopoxviruses in general. In agreement with that, we also demonstrated that chemical optimization leads to compounds with EC50 values in the sub-nanomolar range, associated with low cytotoxicity, which forms a good basis for future drug development from this chemical series.

Facile Construction of Polypropylene Foam with Dense Oriented Cell Structure and Enhancing-ductility Mechanism

Common polypropylene (PP) foam exhibited intrinsic inferior ductility and mechanical strength, which restricted its application as lightweight structural parts. To improve the ductility and mechanical strength of PP foam, the highly oriented PP component with fibrillar structure (cold-drawn fiber, CDF) was blended with isotropic PP resin to prepare PP/CDF foam via a facile foam injection molding process. During foaming at 170°C, CDF was not melted completely. Then, the remaining fibrils acted as shish structure and induced the crystallization of PP chains on its surface to form oriented kebab crystals, and the viscoelasticity and melt strength of the system were significantly improved, which promoted the nucleation of the bubble and the elongation of the cells, constructing a dense oriented cell structure with a large number of slender cylindrical cell walls for the foam. Such cell wall structure was prone to large plastic deformation and continuous elongation under load, which reduced stress concentration and absorbed a significant amount of tensile energy. As a result, a ductile and strong PP/CDF foam was successfully constructed, which exhibited roughly 465% increase in strain at break and 15% increase in tensile strength, respectively compared with PP foam.

Finite element simulation of hybrid manufacturing of Ti–6Al–4 V by arc-directed energy deposition and friction stir processing

ABSTRACT FSP is a novel technology that can improve the microstructure and mechanical properties of ADED. In this study, an FSP-ADED hybrid manufacturing finite element model was constructed for stress and strain simulating the Ti–6Al–4 V alloy. The results show that continuous shrinkage of the deposition wall was broken after inter-layer FSP. The minimum tensile RS was obtained near the wall top. The tensile RS was increased after the deposition of the second layer; however, the overall stress level was lower than that of ADED alone. After two layers of FSP, the average value of longitudinal stress in the stirred zone was reduced by 54%. The warping deformation of hybrid manufactured components was reduced by 30.9%. It was proved that FSP-ADED hybrid manufacturing is an effective method to reduce RS and deformation of titanium alloy large-scale structural parts in the aerospace field.

Online in situ detection of deposited height deviation during additive manufacturing

Deposited height deviation (DHD) of printed layers is a common surface defect that restricts vertical printing accuracy during the additive manufacturing process. The accumulation of DHD layer by layer inevitably leads to the failure of subsequent additive manufacturing tasks. Therefore, accurate online measurement of DHD is crucial. This study proposed a novel amplification computer-vision measurement (ACVM) method that effectively utilizes both melt pool images and temperature information, achieving a DHD detection sensitivity of approximately 9.96 μm. Theoretical connections between image features and DHD, as well as the theoretical associations between instantaneous temperature characteristic and DHD, have been systematically deduced. Based on these two theoretical relationships, DHD can be accurately and synchronously detected directly through the positions of image features and temperature. A single-camera dual-channel multi-signal detection (SDMD) system was developed and implemented within a laser-engineered net shaping (LENS) additive manufacturing system. Subsequently, an online measuring and verification experiment was designed to assess the height deviation of thin-walled structural parts. The experimental results demonstrated that the ACVM method provided an early response to DHD. The method exhibits significant technical application value in quality control in future.

Thermo‐Mechanical Study on Auxetic Shape Memory Periodic Open Cellular Structures—Part I: Characterization of Reentrant Geometry and Effective Heat Conductivity

Periodic open cellular structures (POCS) are additively manufactured supports for heterogeneous catalysts in the field of chemical reaction engineering. Constructed from a repeated unit cell, POCS offer excellent heat transport characteristics due to heat conduction in the continuous solid matrix. However, when inserted into tubular reactors, a loose fit between structure and tube wall results. This considerably hinders heat transfer across the wall. The novel POCS concept presented in this work aims at an intensified wall heat transfer by utilizing a reentrant structure design to ensure auxetic behavior. If the POCS is made of shape memory alloy, it can recover its original shape. Combining these two effects with an initial radial oversize, an interference fit with the tube is established. This contribution comprises the geometric description of reentrant POCS and heat conduction simulations for characterization of the effective heat conductivity, yielding scaling correlations dependent on geometric parameters. Moreover, the effective radial heat conductivity of POCS in cylindrical shape is explicitly investigated. The influencing factor identified is the ratio of tube diameter and cell size: while the ratio increases, the effective radial heat conductivity decreases, but remains well above the effective heat conductivity of the unit cell.

Inflammatory bowel disease and risk of ophthalmic inflammation-related diseases: a two-sample Mendelian randomization study.

To investigate the causal effect of inflammatory bowel disease (IBD) on ocular inflammation using Mendelian randomization (MR) analysis. Genetic instruments associated with inflammatory bowel disease (IBD), ulcerative colitis (UC), and Crohn's disease (CD) were derived from the largest genome-wide association studies (GWAS) published to date. The FinnGen research project was utilized to identify genetic risk variants associated with conjunctivitis, keratitis, iridocyclitis, chorioretinitis, episcleritis, and optic neuritis. All participants were of European ancestry. Three methods which included inverse variance weighting (IVW), weighted median (WM), and MR-Egger regression were performed to estimate the causal association in this study. IVW took the inverse variance of each study as the weight to calculate the weighted average of effect sizes, to summarize the effect sizes of multiple independent studies, which could provide the most precise estimated results. IVW was used as the primary outcome, while WM and MR-Egger were used to improve the estimation of IVW. A nominal causal effect of genetically predicted IBD on risk of non-infectious conjunctivitis, keratitis, iridocyclitis, and optic neuritis, but not on chorioretinitis or episcleritis. After Bonferroni correction, the results showed that genetically predicted UC was significantly associated with an increased risk of iridocyclitis (IVW: OR, 1.17; 95%CI, 1.10-1.24, P=2.54×10-7). CD was significantly associated with conjunctivitis (IVW: OR, 1.05; 95%CI, 1.03-1.08, P=3.20×10-5), keratitis (IVW: OR, 1.06; 95%CI, 1.02-1.09; P=1.13×10-3), and iridocyclitis (IVW: OR, 1.09; 95%CI, 1.04-1.14; P=1.43×10-4). IBD causally poses a risk of inflammation of conjunctiva, cornea, Iris-ciliary body complex, and optic neuritis. CD is more closely associated with the eye inflammation than UC. These impliy that the relationship of IBD and different parts of the eye structure are different, and provide novel evidence linking based on the association of the gut-eye axis.

The Complex Structure of the Abell 548–Abell 3367 Region

Archival XMM and ROSAT X-Ray data are used to investigate the structure of the Abell 548–Abell 3367 region. Based on previous optical studies, this is a region likely to be rich in structure, although studies are in disagreement regarding the connection between Abell 3367 and Abell 548. We use the available archival X-Ray data together with kinematic data of counterpart galaxies to address this question and determine the structure in this region. The region is particularly rich in X-Ray structure elongated along a SW-NE axis and consisting of numerous extended X-Ray sources. In general, the structure consists of many galaxy groups and clusters which appear segregated in X-Ray luminosity, with the least luminous ~30% toward the outer region of the clusters, possibly tracing a filament. We find evidence to suggest a supercluster of three clusters at redshifts ~0.04, 0.045, and 0.06. Several of the X-Ray sources coincident with Abell 3367 have counterpart galaxy redshifts consistent with Abell 548, while others are significantly higher. This supports the formation of a supercluster consisting of Abell 548 and Abell 3667, with the higher-redshift X-Ray source being a background object. In addition, they are part of a larger structure consisting of a previously identified cluster at redshift 0.04 and two groups at redshift ~0.06. There is also filamentary structure at z ~0.103. The ubiquity of groups in the large-scale structure suggests that they provide an environment where galaxies are in close proximity and evolution via interaction can proceed well before the galaxies make their way into the dense central region of a cluster.

Assessing the impact of structural modifications in the construction of surveillance network for Peste des petits ruminants disease in Nigeria: The role of backbone and sentinel nodes.

Peste des petits ruminants (PPR) is a highly contagious disease affecting mainly sheep and goats. Livestock movements contribute to the spread of the disease by introducing it to naive areas or exposing susceptible animals to it in infected regions. Because of its socio-economic impact, the Food and Agriculture Organisation (FAO) and the World Organization for Animal Health (WOAH) have set the goal to eradicate it by 2030, one of the key steps being the improvement of surveillance networks. The present study aimed to provide tools to identify areas that could serve as sentinel nodes, i.e. areas that may be rapidly infected at the onset of epidemics. Using data from a market survey conducted in Northern Nigeria, we reconstructed the small ruminants mobility network and simulated the diffusion of PPR virus through animal movement. From the analysis of simulation outcomes, we investigated which nodes could act as sentinel nodes under specific conditions for disease transmission. We considered several modified networks to get around the problem of data only being available for part of the overall network structure and to account for potential errors made during the field study. For each configuration, we simulated the spread of PPR using a stochastic Susceptible-Infectious (SI) model based on animal movements to assess the epidemics' extent and the presence of recurrent patterns to identify potential sentinel nodes. We extracted the backbone of the reference network and checked for the presence of sentinel nodes within it. We investigated how the origin (seed) of the epidemics could affect the propagation pattern by comparing and grouping seeds based on their respective transmission paths. Results showed that the isolated backbone contains 45% of sentinel nodes that remain stable or undergo only minor changes in 9 out of 11 configurations. On top of that, the characteristics of sentinel nodes identified in the backbone are not influenced by the severity of the disease. The H index, in-degree, and eigenvector are the most essential variables. This study provides an overview of the major axes of animal movements in Nigeria and the most vulnerable locations that should be prioritized for monitoring livestock diseases like PPR.

Microstructures and mechanical properties of pure copper manufactured by high-strength laser powder bed fusion

Pure copper is widely used in motor windings, heat exchangers and aerospace engines because of its high electrical and thermal conductivity. High-strength laser powder bed fusion (HS-LPBF) not only allows rapid production of components with complex geometry and high spatial resolution, but also offers various advantages such as small focal spot diameter, fine powder, and small layer thickness, providing advantages for forming complex structural parts in fields such as engines and heat exchangers. A single factor single layer experiment was performed by varying the hatch spacing (H), and the range of hatch spacing was determined according to the overlap rate. The degree of influence of process parameters on the relative density of pure copper specimens was analyzed using an orthogonal experiment, and a comparative study of the phase composition, microstructure and mechanical properties of pure copper specimens was carried out by varying the laser power. The characteristics of pure copper formed by HS-LPBF were analyzed. In addition, the effect of heat treatment on the microstructure and mechanical properties of pure copper specimens was investigated, and the fracture morphology of the specimens was observed comparatively. The results show that the HS-LPBF technique can effectively increase the energy density and improve the specific surface area of the powder and the laser absorptivity due to its small focal spot diameter, fine powder and layer thickness, thus reducing the minimum energy required to melt pure copper powder. The optimum process parameters were obtained by orthogonal experiment with a relative density of 98.1 % of the specimen. The highest hardness, ultimate tensile strength and elongation were obtained at a laser power of 260 W with 84 HV, 320 MPa and 17.8 %, respectively. This ultimate tensile strength is 18 % higher than the highest ultimate tensile strength that has been reported so far. In addition, the average grain size of the optimal specimens was 3.6 µm. Mechanical properties such as hardness, tensile strength and elongation of pure copper parts can be significantly improved by precisely controlling the process parameters, in particular laser power and hatch spacing.

Multi-Metal Additive Manufacturing by Extrusion-Based 3D Printing for Structural Applications: A Review

Additive manufacturing (AM) is a rapidly developing technical field that is becoming an irreplaceable tool to fabricate unique complex-shaped parts in aerospace, the automotive industry, medicine, and so on. One of the most promising directions for AM application is the design and production of multi-material components with different types of chemical, structural, and architectural gradients that also promote a breakthrough in bio-inspired approaches. At the moment there are a lot of different AM techniques involving various types of materials. This paper represents a review of extrusion-based AM techniques using metal-polymer composites for structural metal parts fabrication. These methods are significantly cheaper than powder bed fusion (PBF) and directed energy deposition (DED) techniques, though have a lower degree of part detail. Thus, they can be used for low-scale production of the parts that are not rentable to produce with PBF and DED. Multi-material structures application in machinery, main aspects of feedstock preparation, the subsequent steps of extrusion-based 3D printing, and the following treatment for manufacturing single-metallic and multi-metallic parts are considered. Main challenges and recommendations are also discussed. Multi-metallic extrusion-based 3D printing is just a nascent trend requiring further wide investigation, though even now it shows pretty interesting results.

Research on passive adaptive wall-climbing cleaning and inspection robot of marine cylindrical steel structure based on conical magnetic adsorption wheel

The marine growth cleaning and structural defect detection of steel structures of offshore underwater facilities are essential parts of the inspection and maintenance of offshore platforms. However, a majority part of underwater structures of offshore facilities, such as offshore wind turbines, Jacket platforms, Jack-up platforms, etc., are cylindrical structures. Compared with the planar structures, cylindrical structures have large curvature, and less supporting area, and therefore put forward higher requirements for the performance of the attached surface working robot. This paper proposes a wall-climbing cleaning robot that can move freely on the wall of cylindrical steel structures and passively adapt to cylindrical structures with various curvatures and diameters. According to the structural characteristics of the robot, a static failure model is established to analyze the different instability forms of the robot and the minimum critical magnetic adsorption force is determined. To ensure the minimum mass and the maximum magnetic adsorption force of the conical magnetic adsorption wheelsets, the effects of air gap and cone angle on the performance of the conical magnetic adsorption wheelsets were analyzed parametrically, and the optimal structural size was obtained. Finally, the mobility and capability of the robot on the surface of the different diameter cylindrical structures has been validated through prototype experiments.