Proper Connection Research Articles

On the selection of a proper connection in describing the dynamics of constrained mechanical systems

This study is focused on a critical issue related to the direct and consistent application of Newton’s law of motion to a special but large class of mechanical systems, involving equality motion constraints. For these systems, it is advantageous to employ the general analytical dynamics framework, where their motion is represented by a curve on a non-flat configuration manifold. The geometric properties of this manifold, providing the information needed for setting up the equations of motion of the system examined, are fully determined by two mathematical entities. The first of them is the metric tensor, whose components at each point of the manifold are obtained by considering the kinetic energy of the system. The second geometric entity is known as the connection of the manifold. In dynamics, the components of the connection are established by using the set of the motion constraints imposed on the original system and provide the torsion and curvature properties of the manifold. Despite its critical role in the dynamics of constrained systems, the significance of the connection has not been investigated yet at a sufficient level in the current engineering literature. The main objective of the present work is to first provide a systematic way for selecting this geometric entity and then illustrate its role and importance in describing the dynamics of constrained systems.

Experimental studies of external panels as a method of structural failure prevention

The openwork facades play a significant role in modern masonry construction, mostly due to their architectural values, as well as some structural aspects, including the use of “lightweight solution”. This type of external facade walls are usually made in-situ, and the safety of their use is ensured by the proper connection (using systemic solutions) with the load-bearing layer of the enclose wall. However, the seasonality of masonry work (in certain climatic zones), extravagant architectural solutions (sloping and hanging facades) or the requirement for disassembly and reassembly of the facade make the in-situ technology completely useless. The only solution in such situations is the use of prefabricated masonry panels. Unfortunately, in the absence of any design guidelines, these elements require an individual approach to design issues using the concept of “design by testing”.The paper presents a unique and experimental research of prefabricated panels forming an openwork facade subjected to out-of-plane bending. Two-stage laboratory tests were carried out. The first one involved checking the feasibility and correctness of the first type of panels in accordance with the architectural idea (concept 1), along with an experimental determination of the basic strength parameters of the panel components. The second stage of study included laboratory tests of panels with a modified structure, proposed by the authors of the paper (concept 2), and a simplified analysis of the load capacity assessment. The applied modification made it possible to prevent structural damage to the elements and ensure safety at every stage of the element's operation, that is, fabrication, installation and use.

Proper (Strong) Rainbow Connection and Proper (Strong) Rainbow Vertex Connection of Some Special Graphs

The proper rainbow vertex connection number of [Formula: see text], denoted by [Formula: see text], is the smallest number of colors needed to properly color the vertices of [Formula: see text] so that [Formula: see text] is rainbow vertex connected. The proper strong rainbow vertex connection number of [Formula: see text], denoted by [Formula: see text], is the smallest number of colors needed to properly color the vertices of [Formula: see text] so that [Formula: see text] is strong rainbow vertex connected. These two concepts are inspired by the concept of proper (strong) rainbow connection number of graphs. In this paper, we first determine the values of [Formula: see text] and [Formula: see text] for some special graphs, such as all cubic graphs of order [Formula: see text], pencil graphs, circular ladders or Möbius ladders. Secondly, we obtain the values of [Formula: see text] and [Formula: see text] for some special graphs, such as all cubic graphs of order [Formula: see text], paths, cycles, wheels, complete multipartite graphs, pencil graphs, circular ladders and Möbius ladders. Finally, we characterize all the connected graphs [Formula: see text] with [Formula: see text] and [Formula: see text].

Graphs with (strong) proper connection numbers [formula omitted] and [formula omitted

In 2016, Lumduanhom et al. determined all graphs of size m with PC-number or SPC-number m−1, m−2, m−3. But we find that the graphs with SPC-number m−3 are not completely characterized. In this article, we characterize all graphs with SPC-number m−3. Moreover, we present all graphs satisfying PC-number or SPC-number m−4.

Efficacy Assessment of Timber Based In-Plane Strengthening of Wooden Floors on the Seismic Response of Masonry Structures by means of DEM Analyses

Masonry buildings are highly vulnerable to seismic loading, and their dynamic response is strongly influenced by the timber floor in-plane deformability and by the quality of the wall-to-floor connections. Understanding the behavior of timber floors and roofs and their interaction with the masonry walls is therefore important for the protection of historical buildings. In a previous research project, different timber-based dry-connected floor strengthening solutions were tested under in-plane loads. The experimental results show a significant increase in shear strength and stiffness.Discrete Element Method is here used to evaluate the effectiveness of the strengthening solutions in avoiding the triggering of the out-of-plane collapse of masonry walls, first on a simple masonry cell, and then on a heritage listed masonry building. A detailed cyclic model of the floor behavior was implemented: the unreinforced and reinforced floors were described by beams connected with non-linear springs, reproducing the experimental hysteretic response. Both the case studies highlight the effectiveness of the strengthening solutions in reducing the out-of-plane displacements of masonry walls, confirmed also by a comparison with the ideal rigid diaphragm case. The reinforced floor is able to transfer the seismic forces to the shear-resistant walls. The out-of-plane displacements are compatible with the wall capacity, and the reinforced floor hysteretic cycles contribute to dissipate part of the input energy. Moreover, a proper connection design can also cap the transferred seismic forces to an acceptable level for shear-resistant walls.

Pull-out tests on injected steel anchors in a masonry tuff wallet

Recent seismic events demonstrated that the high vulnerability of existing masonry buildings is often related to the out-of-plane failure of perimetral walls. Lack of a proper connection with adjacent walls or slabs may favorite a premature overturing failure (first mode) significantly compromising the performance of the entire building. Nowadays, several strengthening techniques are available on the market and they are effective in increasing the connection with adjacent walls. The use of mechanical anchors made with classic (steel) or innovative (composite) materials is an effective and widely used technique. They can be often installed operating from the exterior of the building, thus reducing the disruption of the intervention and the downtime related to installation process. Although many experimental and analytical studies demonstrating the effectiveness of the injected anchors are available in literature, several aspects still need to be investigated.This research paper deals with the experimental response of injected steel anchors extracted from a full-scale tuff-masonry wall. The wall was fabricated in a laboratory environment and six anchors were extracted varying the diameter of the bar, the location (center or side of the wall) and the axial pressure.A direct comparison of the results and of the observed failure mode is reported. The main outcomes and the variability of the strength of the anchors with the main studied variables are discussed.

Cytokines, NK cells and regulatory T cell functions in normal pregnancy and reproductive failures.

Pregnancy brings about an intricate assortment of dynamic changes, which causes proper connection of genetically discordant maternal and foetal tissues. Uterine NK cells are immune cells populating the endometrium and play a major role in implantation and also regulate placentation. This review mainly aims explore the role of uterine NK cells in implantation and how it is affecting in adverse pregnancy outcomes. Though the functions of uterine NK (uNK) cells are not clearly understood, NK cell activity plays a vital role during immunomodulation which is the main step in implantation and sustaining the early pregnancy. Cytokines, cell surface receptors of NK cells and hormones such as progesterone modulate the NK cell activity in turn affect the implantation of the embryo. Altered NK cell activity (number and functionality) would be an important attributing factor in adverse pregnancy outcomes. Furthermore, T regulatory cells and cytokines also modulate the immune responses in the decidua which in turn contributes to successful implantation of embryos. Immunological responses and interactions in the Foetus-maternal interface is crucial in the successful implantation of allogenic foetus resulting in a healthy pregnancy. NK cells, Treg cells and cytokines play a major role in successful implantation which remains an enigma. Comprehending pregnancy-induced immunological changes at the foetus-maternal interface will allow newer therapeutic strategies to improve pregnancy outcomes.

Nonlinear Static Analysis of Core Wall RCC Framed Buildings

RCC framed buildings mainly consists of shear walls and columns for resisting lateral force due to earthquakes. In most of the framed buildings shear walls are provided in the outer frames. In addition to shear walls provided in the outer frames, RCC lift -well (core wall) is also provided in the inner core of the buildings to accommodate lift. Core wall also acts as shear wall contributing to the lateral resistance to the buildings. In the present study, nonlinear static analysis is performed to study the behaviour of high rise RCC buildings, the buildings have a centralised lift core wall with a door opening and shear walls in outer frames. The flange of core wall is joined together at regular interval by floor and slabs and connecting beams to provide proper connection in between flange. This Residential G+14 RCC framed building is lying in seismic zone 4 and analysed as per guidelines of is 1893 (part 1) 2016 and ETABS 17.0.1. Responses namely lateral loads, story drift, base shear, story displacement and the formation of plastic hinges compared for two types of buildings, namely with core wall and without core wall to understand the effect of core wall against the lateral loads.

Aluminium metal foam production methods, properties and applications- a review

Aluminium metal foam has a cellular structure. It's lightweight with these unique physical and mechanical properties and widely used in structural and functional applications. This paper's studies show the possible ways to produce Aluminium metal foam and its different properties and, based on that, the field it has applications. During the studies, it is observed that the Aluminium metal foam can develop in two ways: solid route and liquid route, after acquiring unique properties, such as light in weight to strength, suitable acoustic properties, and shock and energy absorption capabilities. The application will be selected based on properties and open or closed pore cells obtained in Aluminium metal foam. The significant finding from the review is that Aluminium metal foam has broad applications. However, the main lacunas that are still Aluminium metal foam are commercially not used because it is challenging to get good properties such as attaining uniform distribution and percentage of porosity in the prepared foam sample and uniform pore size. Another critical factor is that the cost will be high if the liquid or solid route develops the metal foam. So powder metallurgy process is the best method to produce metal foam to get better surface integrity and a proper network connection between each pore.

Hairpin Windings for Electric Vehicle Motors: Modeling and Investigation of AC Loss-Mitigating Approaches

The hairpin winding configuration has been attracting attention as a solution to increase the power density of electric vehicle motors by enhancing the slot-filling factor. However, this winding configuration brings high AC losses during high-speed operation and we require new approaches to tackle this challenge. This paper considers reducing AC losses by proposing two main methods: correct transposition of conductors in parallel paths, and enhancing the number of conductor layers in a slot. First, the proper connection of conductors in parallel paths is considered, and the essential rules for this purpose are described. Next, the paper uses a numerical approach to deal with the effect of incorrect conductor transposition in winding paths on generating additional AC losses due to circulating currents. Finally, the impact of the number of conductor layers in the mitigation of AC losses is also discussed in detail. According to the results, by increasing the number of layers, ohmic losses in the layer near the slot opening dramatically decrease. For instance, ohmic losses in the layer near the slot opening of the eight-layer setup were 82% less than the two-layer layout.

Degree sums and proper connection number of graphs

An edge-colored graph G is called properly connected if any two vertices are connected by a properly colored path. The proper connection number of a graph G , denoted by p c ( G ) , is the smallest number of colors that are needed to color G such that it is properly connected. A separating vertex of G is bad if it is contained in at least three blocks, each of which contains at most three vertices. Let G be a graph of order n without bad vertices. In this paper, we show that if the degree sums of any three nonadjacent vertices of a graph G is at least 3 n / 4 and n > 48 , then p c ( G ) = 2 , which generalizes the results due to Borozan et al. (2012) and Chang et al. (2019).

Global stiffness and residual stresses in spinal fixator systems: A validated finite element study on the interconnection mechanism

Posterior spinal fixation systems are the gold standard to treat different column disorders using rods and screws. The proper connection between them is guaranteed by the Interconnection Mechanism (IM), consisting of different metallic subcomponents held together through the application of tightening torque. The response of the fixation system is defined by its overall stiffness, which in turn is governed by the local residual stress field arising during tightening. Although literature computational models for studying spinal fixation are becoming increasingly anatomically complex, most studies disregard completely the realistic modeling of the IM, namely choosing elastic-plastic material models and proper contact interactions. In this frame, the present study aims at increasing awareness in the field of spinal fixation modeling by investigating the mechanical response of the IM in terms of overall stiffness and local residual stresses. Once validated through dedicated experiments, the results of the proposed model have been compared with the current literature, highlighting the key role of the IM in the reliable modeling of spinal fixation.

Vertical and Horizontal Comparison as well as Referential Perfection of the Cohesion Between Inspection and Supervision in China and South Korea Under the Background of Judicial Reform

As China revised the Criminal Procedure Law in 2018, new requirements were put forward for procuratorial organs in the investigation of duty crimes, that is, proper connection and mutual cooperation. However, the cases investigated by the newly established national highest supervisory agency, the supervisory committee, are transferred to the people’s procuratorates. Thus, when the handling methods of cases accepted by the people’s procuratorates are based on the inconsistency between the provisions of the Supervision Law and the Criminal Procedure Law, the supervisory agencies and procuratorial agencies are faced with the connection of litigation procedures. From a horizontal point of view, this paper compares the procedures of cohesion between inspection and supervision in China and South Korea. Meanwhile, it grasps the unclear jurisdiction and intervention in the current cohesion process vertically to discuss the necessity and adaptability of system design. It puts forward that the evidence chain connection, the system establishment of case handling communication and coordination, and the procuratorate’s early intervention and the supervisory agency’s opinion are the rational thinking to promote the procedure cohesion, which helps clarify the duty crime case handling and ensures the logical consistency of the inspection and supervision cohesion system.

Investigating the Relation between Thrust Networks and Thrust Surfaces for Masonry Domes subjected to Vertical Loads: A Case Study

ABSTRACT Thrust Network Analysis and Thrust Surface Analysis are two well-established methods for studying the stability of vaulted masonry structures. Working within the framework of limit analysis and adopting the well-known Heyman hypotheses, both methods search for generalized statically admissible stress fields in historical masonry constructions. Although these two methods are sometimes considered to be linked, it is still unclear how this link can effectively be exploited from a practical standpoint. In this paper, we focus our attention on the conditions that enable establishing a proper connection between the two methods, which are based on different structural models, and we apply them to a case study, the dome of Pisa Cathedral. The analogies and differences in the results obtained are highlighted, and the feasibility in practice of a possible method combining thrust network and thrust surface is checked.

Conductance of electrostatic wire junctions in bilayer graphene

The conductance of electrostatic wire junctions in bilayer graphene, classified as trivial-trivial or trivial-topological regarding the confinement character on each junction side, is calculated. The topological side always corresponds to a kink-antikink system, as required for a proper connection with a trivial side. We report a conductance quench of the trivial-topological junction, with a conductance near quantization to $4{e}^{2}/h$, which is only half of the maximum value allowed by the Chern number of a kink-antikink system. The analysis allowed us to uncover the existence of a chiral edge mode in the trivial wire under quite general conditions. A double junction, trivial-topological-trivial, displays periodic Fano-like conductance resonances (dips or peaks) induced by the created topological loop.

Multi-electrode platform for selective electrochemical sensing: 3D-printed insulating plastic is turned into a five-electrodes chip

We report a method to turn a 3D-printed plastic piece into a five-electrodes chip for multiple analytes detection. A chip containing Pd, Ni, and Ru working electrodes is used to sense hydroquinone, acetaminophen, salicylic acid, and hydroxychloroquine at once. The analysis is sequentially achieved simply by changing the proper electrode connection, without changing mobile parts, neither adding reactants, nor electrolytes. This strategy is an alternative for low-cost selective electrochemical detection.

Designing a robust cyber‐attack detection and identification algorithm for DC microgrids based on Kalman filter with unknown input observer

In recent years, microgrids (MGs) have attracted much attention from researchers due to the aggregation of distributed generation (DG) sources for visibility purposes, proper connection of these DGs and the power system, as well as more efficient control of the sources. However, high reliance on communication networks makes MGs vulnerable to deliberate cyber-attacks. Also, since the basis of attack detection is to process monitoring and state estimation of the system, this paper presents a Kalman filter (KF) algorithm to monitor the network while modelling MGs in the state space. Moreover, as uncertainty and disturbance are two critical challenges in modelling and estimating states of a system, robust detection of cyber-attacks along with separation of the effect of disturbances and uncertainties are of particular importance. Therefore, in this study, a novel attack reconstruction algorithm is designed using a combination of an unknown input observer method and KF for robust attack detection. Simulation results show excellent performance of the proposed approach in detecting, identifying and neutralizing the effect of cyber-attacks in the presence of disturbance and noise.

Role of Histone Chaperone APLF in Mammalian Embryo Development

Embryonic development involves orchestrated events regulated by a plethora of factors. Epigenetic regulation is one such key aspect regulating embryonic development. We are investigating the role played by Aprataxin and PNK‐like factor (APLF), a histone chaperone, in regulating cellular transitions in the context of embryonic development. APLF is documented as a DNA damage‐specific histone chaperone and has already been studied in our lab in the context of the generation of induced pluripotent stem cells and breast cancer metastasis as a regulator of epithelial to mesenchymal transition.We are looking into the expression profile, functional role, and mechanism of action of APLF in embryonic development. The expression study in pre‐and post‐implantation mouse embryos and mouse trophoblast stem cells (TS) through different days of differentiation showed a dynamic expression pattern of APLF, clearly indicating prospective functional significance. The localization of APLF in mouse embryos was enhanced in trophectoderm (TE) and lineages derived from TE, which contributes to the extraembryonic lineage crucial for developing a proper maternal‐fetal connection. Functional studies by sh RNA mediated knockdown (KD) of Aplf in mouse embryos by microinjection induced the hatching of embryos in vitro at E3.75, with a significant increase in Cadherin 1 (Cdh1) and Caudal‐type homeobox 2 (Cdx2) expression. Hatching is a crucial event whereby the embryo breaks out of the protective sheath called zona pellucida and prepares itself to attach itself to the uterine wall by the process of implantation. The Aplf KD embryos failed to implant in vivo. Rescue experiments neutralized the effects of AplfKD both in vitro and in vivo. We used differentiated TS cells as our model system to understand the mechanism behind the observed phenotype in Aplf KD embryos. Reduced expression of Snail Family Transcriptional Repressor 2 (Snai2) and TEA Domain Transcription Factor 4 (Tead4), and the gain in Cdh1 level, marked the differentiation of AplfKD TS cells. Embryo implantation is one of the pioneer developmental stages where EMT comes into action. Significantly high level of epithelial marker Cdh1 and downregulation of mesenchymal marker Snai2 in Aplf KD TS cells would have impaired the crucial EMT process operational during implantation.Further studies are being conducted to unravel the underlying mechanism completely. Hence, our findings suggest a novel role for APLF during the implantation and post‐implantation development of mouse embryos. As we observed these phenotypes in the mouse embryo, we checked APLF expression in the human placenta, and interestingly, our preliminary studies showed its expression in cytotrophoblast and syncytiotrophoblast cells. As we have seen that a delicate balance of APLF is crucial to achieve implantation and attain proper pregnancy, we anticipate that it would contribute to establishing a felicitous maternal‐fetal connection.

Some results on the total properk-connection number

AbstractIn this paper, we first investigate the total proper connection number of a graphGGaccording to some constraints ofG¯\overline{G}. Next, we investigate the total proper connection numbers of graphGGwith large clique numberω(G)=n−s\omega \left(G)=n-sfor1≤s≤31\le s\le 3. Finally, we determine the total properkk-connection numbers of circular ladders, Möbius ladders and all small cubic graphs of order 8 or less.

Mechanical performance of pre-engineered closed section beam-column connections in CFS frames: Experimental investigation

The mechanical performance of connector types is essential for promoting the application of pre-engineered lightweight cold-formed steel structures with closed sections. In this paper, two types of pre-engineered fabricated beam-column connections with popular connectors were innovatively proposed, and full-scale static experiments were implemented. The mechanical performance and the component parameter variations of the pre-engineered fabricated connections were systematically investigated and quantificationally compared. It’s worth noting from experimental results that the ultimate capacity and initial stiffness of the proposed beam-column connections with the core-pulling rivets increased by 79.3% and 34.3%, respectively compared to those of self-tapping screws. The ultimate moment and initial stiffness of connections with self-tapping screws can be promoted with the diameter dimension increase of self-tapping screws. The ultimate moment and initial stiffness of the connection with lateral angle steels decreased by 29.9% and 40.6%, respectively than those with beam supports up and down. The proper connection types and connectors can be comprehensively determined based on the mechanical performance and engineering construction requests.