Connection Failure Research Articles

A Survey on Emerging Trends and Applications of 5G and 6G to Healthcare Environments

A delay, interruption, or failure in the wireless connection has a significant impact on the performance of wirelessly connected medical equipment. Researchers presented the fastest technological innovations and industrial changes to address these problems and improve the applications of information and communication technology. The development of the 6G communication infrastructure was greatly aided by the use of Block-chain technology, artificial intelligence (AI), virtual reality (VR), and the Internet of Things (IoT). In this paper, we comprehensively discuss 6G technologies enhancement, its fundamental architecture, difficulties, and other issues associated with it. In addition, the outcomes of our research help make 6G technology more applicable to real-world medical environments. The most important thing that this study has contributed is an explanation of the path that future research will take and the current state of the art. This study might serve as a jumping-off point for future researchers in the academic world who are interested in investigating the possibilities of 6G technological developments.

Long-term outcomes in women diagnosed with heart failure in connection to delivery

Abstract Background Heart failure (HF) among young patients may be from various causes, often triggered by heightened physical demands like pregnancy. Data regarding outcomes of women diagnosed with HF in conjunction to pregnancy and delivery are varied. There remains a notable gap in understanding the outcomes observed in women diagnosed with heart failure in conjunction with delivery. Also, long-term follow-up studies are crucial to elucidate the impact of pregnancy-associated HF on future cardiovascular. Purpose To study the interplay between pregnancy, HF, and subsequent cardiovascular risk. Method Using the personal identification numbers (PINs) that all individuals in Sweden have enables linkage of data between different registers. Data from the National Patient Register (NPR), Swedish Medical Birth Register (MBR) and the Cause of Death Register were also used. All women 18 to 50 years of age registered in the in MBR in the period 1st January 1997 to 31st December 2019 were included. Women with first-time HF in relation to delivery were identified using the international classification code for diseases (ICD-10) I50, I42, I43 and 090.3 together with co-morbidities. Every patient was compared with 5 controls without HF from the Total Population Register matched on age at delivery and calendar year of delivery. Outcomes: all-cause mortality, and any cardiovascular disease (CVD) diagnosed during the observation time. Results A total of 286 cases and 1,430 controls were included. The prevalence of comorbidities at baseline for both patients and controls was low; congenital heart disease (1.4%, vs. 0%), pulmonary hypertension (1.0% vs. 0%), valvular heart disease (5.9% vs. 0%), myocardial infarction 0.7% vs. 0%), arrhythmia (5.9% vs. 0%), hypertension (6.3 % vs. 0.1%), (all p<0.05). Preeclampsia prior to HF diagnosis had 31% of patients vs. 0.2% of controls (p<0.001). Patients exhibited higher mortality rates at 4.9% during median follow up 9.0 (IQR 5.6-13.0) years vs. 0.3%, median follow up 9.4 (6.2-13.5) years and hazard ratios (HR) for all-cause mortality HR (95% CI) of 18.20 (5.99 - 55.31) (p<0.001) compared to controls. During median follow up of 3.2 (0.0-9.2) years 60.1% of patients were diagnosed with CVD both at in-/out-patient settings compared with 4.1% in controls during 9.4 (5.8-13.5) years of follow up. Comparing patients with controls the HR (95% CI) was 22.24 (16.50 - 29.96) p<0.0001 for CVD diagnosis during follow-up, see Figure 1. Conclusion In conjunction with delivery, and in the years thereafter, women with heart failure diagnosis had more than eighteen times higher risk of mortality than women without heart failure. The risk of CVD event in the heart failure group is highest in conjunction with delivery. Figure 1. Cumulative incidence functions for all-cause mortality, CVD in- or out-patient visit adjusted for death as competing risk, comparing cases with controls.

Fatigue Strength Analysis of Rail Fastening Baseplate

Superstructural elements of a railway track experience dynamic loads varying over time. As a consequence, this is accompanied by the initiation and accumulation of fatigue damages. Defects in intermediate rail fastening are quite difficult to identify using flaw detection methods, and some can be destructed. In particular, rail fastening baseplates often fail due to insufficient fatigue strength.Purpose: To investigate the fatigue strength of rail fastening baseplate.Methodology: Development of the mathematical model of deformation based on the finite element method (FEM). Strength analysis of the baseplate using the model of a variable-thickness slab resting on a nonlinear elastic foundation. The latter is modeled by a set of rods with nonlinear deformation and parameters determined by compression tests of the baseplate. A mathematical model developed in COSMOS software for the FE analysis of the stress-strain state of the baseplate at a time-varying load from rolling equipment and assembly forces from attaching the baseplate to the sleeper and rail.Research findings: The cyclic loading parameters are obtained at dangerous points of the baseplate and its durability is analyzed at different loads with respect to unevenness of track settlement and failure of bolt connections of rail fasteners. The influence of these factors on actual loads on the rail fastener is determined. It is found that the service life of the baseplate mainly depends on the dynamic load.

Shear performance of perfobond leiste (PBL) connectors in engineered cementitious composites (ECC)

Substituting normal concrete with ductile Engineered Cementitious Composites (ECC) is a promising way to address the safety and durability issues caused by cracking in steel-concrete composite structures. To realize a synergistic deformation behavior between steel and ECC, Perfobond Leiste (PBL) shear connectors are preferred to be used owing to their superior shear resistance, shear stiffness, and excellent fatigue performance. This research comprehensively investigated the shear performance of PBL connectors in ECC through experimental, numerical, and analytical approaches. Firstly, the shear load-slip relationships of PBL connectors in ECC and concrete were studied through push-out tests of 36 H-shaped specimens. It indicated that the fracture of penetrating bars dominated the final failure of PBL connectors in ECC, whereas premature concrete spalling happened in concrete specimens. By establishing a refined finite element model, the parametric study was then conducted to clarify the influence of the compressive strength of ECC, hole diameter, penetrating bar diameter, and penetrated plate thickness on the shear characteristics of PBL connectors in ECC. Finally, an analytical model for predicting the shear carrying capacity of PBL connectors embedded in ECC was derived, matching well with the test results.

Mechanical model analysis of column-footing joints with combined socket-corrugated pipe connection

The socket connection method is widely used in precast column, particularly in seismic regions. However, reducing the socket-depth to lower costs may lead to shear failure in the socketed part of the columns. To address this issue and achieve cost objectives, a new approach combines shallow sockets with corrugated pipes for column-footing joints. Comparative tests were conducted to investigate failure in columns with socket-corrugated pipe connections (SCPC), shallow sockets (SSC), and cast-in-place (CIP). Furthermore, finite element models were employed to validate the experimental and simplified model results. The findings suggest potential shear failure in shallow socket connections, which can be mitigated by using the combined socket-corrugated pipe method that alters force transmission paths. As the axial load ratio increases, both the ultimate lateral load capacity of the specimen and the local stresses at the column base increase. In addition, the ultimate lateral load capacity of the column and the stress of the connection reinforcement are increased by increasing the strength of the longitudinal reinforcement, consequently amplifying the extent of joint area damage. Finally, a simplified strut-and-tie model of the SCPC, validated against numerical and experimental data, accurately represents force paths, ultimate lateral load capacity and failure modes in socket joints.

Investigation of the electrical quality and long-term stability of aluminum ground stud connections in automotive applications

The rapid advancement in the electrification of modern vehicles has led to a continuous increase in electrical consumers for various comfort and safety functions. Ground studs serve as the electrical interface between the conductive vehicle body and the onboard network. Drawn arc stud welding is an economical and established joining process for producing ground stud joints. The circuits in the onboard network are increasingly subject to greater demands regarding current-carrying capacity and long-term stability. Reliable signal and power transmission require minimal contact resistance at the electrical connection points of the ground stud system and must withstand various operating and environmental conditions over the entire service life. In this study, a ground stud made of AlMg5, with a ZnNi-coated steel cap nut was used on a 2.0 mm thick sheet of AlMg3. The electrical connection of the ground studs was made using tinned copper cable lugs and 35 mm² cables. To analyze the electrical resistance behavior in an accelerated test, the ground studs were subjected to a superimposed load with a cyclic current profile for 1008 hours under changing climatic conditions. The results show that under the chosen operational and environmental conditions, accelerated aging and intermittent resistance behavior occur. A characteristic drop in resistance during the test indicates the failure point of the electrical connection. The cause of failure can be attributed to media penetration into the electrical contact zone. A failure of the electrical connection was observed after 512 hours.

Developing a novel anticipated inherent risk assessment approach applicable in early stages of process design

Inherently Safer Design (ISD), as one of the most fundamental approaches to process safety, focuses on the innate design features. Numerous tools have been developed to assess ISD and risk-based indices are one of the most elevated of them. Existing indices are limited in modelling consequences or are challenging to adapt in terms of probability. This study introduces the Anticipated Inherent Risk Index (AIRI), a robust tool for rapid risk assessment of the worst anticipated scenarios. It incorporates Furthest Effect Distance of the release from the largest connection, by software, and Representative Failure frequency, which is a relative dataset calculated from renown databases. This presents a relative risk map upon major consequences and their likelihood. AIRI applied to a PDH Fractionation Subunits shows that Heat Pump Compressor Suction Drum (AIRI≈3399) in PP Splitter Section, followed by Propylene Trim Condenser (AIRI≈1931) and PP Splitter Reboiler/Condenser (AIRI≈1798) are the equipment with the highest risk. AIRI is a competent tool for early high-level analysis of equipment risk, which gives useful indications on design and how to improve it. This tool also has the potential to be equipped with vaster frequency datasets and effects analysis and to be incorporated into other process safety studies.

Electrical contact reliability investigation of high-speed electrical connectors under fretting wear behavior

Fretting is one of the common phenomena during the use of electrical connectors, which is usually affected by the working environment and has a significant impact on the electrical contact life. In this work, the influence of different fretting wear conditions on electrical contact failure is studied by combining theoretical analysis, finite element simulation and experimental verification. The mechanical and electrical properties are related through experiments in different environments. It can be concluded that the main causes of electrical contact failure are contact structure deterioration and surface coating loss. Increased fretting cycles aggravate the surface fretting wear of high-speed electrical connectors. The failure of electrical connectors can be delayed by a decrease in frequency and amplitude in addition to an increase in coating thickness. The insertion and withdrawal force gradually decreases due to continuous wear. The failure mechanism of electrical contact during wear is also explained. It provides theoretical guidance for predicting the life of electrical connectors.

Modeling the service life of temporary airfield operational surfaces under multi-pass aircraft trafficking

Expeditionary Airfield (EAF) surfacing systems are designed to create temporary aircraft operating surfaces. Modeling the service life of EAF surfacing systems including the matting system, aircraft, and subgrade, has historically proven difficult, exacerbated by variability between systems and the multitude of mechanisms that can constitute failure. The study presented herein outlines the development and implementation of a performance modeling approach that includes a multi-scale scheme that accounts for local characteristics of the connection points of the EAF matting system, coupled to the global characteristics of the matting array to predict cyclic passes to failure. Finite element studies were conducted for an EAF surfacing system brickwork configuration subjected to aircraft strut loads over varying California Bearing Ratio (CBR) subgrades to calibrate a transfer function to full-scale trafficking experiments. The proposed framework is then used to predict the rate of subgrade deformation for additional lay patterns, which successfully ranked the performance of each relative to full-scale trafficking experiments. An approach is proposed to couple the rate of subgrade deformation with local finite element models to capture increasing joint damage as permanent deformation accumulates, and supplemented by a variable amplitude cycle counting and damage accumulation algorithm that yields reasonable agreement with full-scale experiments while capturing the transition in failure mechanisms at higher CBR values. The results of the study presented herein captures the propensity for end connector and subgrade failure over a range of subgrade CBRs and shows promise for a broader performance framework that can be extended to other EAF surfacing systems, aircraft types, and specific matting lay patterns.

Numerical Design Calculation of T-stubs at Elevated Temperatures

AbstractThe failure of steel connections can lead to the progressive collapse of the entire structure. Accurate modelling of steel connections at elevated temperature allows structural fire engineers to design steel structures that may deal with the severity of a fire. The prEN 1993-1-14 proposes numerical design calculation for the static design check of steel connections. This paper presents a component-based finite element model (CBFEM) to design the T-stubs at elevated temperatures. The generated model is verified and validated against the results from the analytical model and experimental study. The resistance, failure modes and the load-deformation curves are used to validate and verify the CBFEM models for steel connection design at elevated temperatures. The results stated that the CBFEM is a practical design tool to model bolted connections at elevated temperatures and it is possible to apply the recommended 5% plastic limit strain by EN 1993-1-5 for fire design of bolted connections.

Experimental Study on the Competitive Failure of Headed Stud Connectors under Freeze–Thaw Cycles

Experimental Study on the Competitive Failure of Headed Stud Connectors under Freeze–Thaw Cycles

Structural behaviour and construction of a monumental ice structure

This paper investigates the use of ice-based materials combined with Fiber-Reinforced Polymer (FRP) to enhance the bending capacity of ice sculptures. Through three-point bending tests and ABAQUS simulations, the study analyses the mechanical behaviour of GFRP and cellulose ice, both separately and together. The results show that FRP improves tensile resistance while cellulose ice adds mass and ductility. An ABAQUS simulation with a layered shell partially captures the mechanical behaviour but has limitations in modelling beyond the elastic phase due to assumptions of perfect connection and material failure. Applied to a monumental sculpture by artist KAWS, incorporating a steel framework, GFRP mould, and ice-based material, the study confirms the potential of combining FRP and cellulose ice to achieve improved structural performance in ice-based sculptures.

Simplified formulas for calculating bearing capacities of standing seam metal roof systems under uniformly distributed downward and upward loads

Finite Element (FE) models of standing seam metal roof systems (SSMRSs) are established and verified by experimental results. A comprehensive parametric study on the bearing capacities of SSMRSs under uniformly distributed loads through FE simulations encompassing 281 SSMRSs is conducted. Simplified formulas for calculating the bearing capacities of SSMRSs under uniformly distributed loads are proposed as functions of fundamental parameters, including roof panel thickness, roof panel width, purlin spacing, material strength, friction coefficient, and support head width. These simplified formulas avoid the necessity for calculating the effective section during the verification of bending failure and avoid the necessity for wind uplift experiments during the verification of connection failure of the SSMRSs in conventional building codes and guidelines. The results show that for per 0.1 mm increase in roof panel thickness, the ultimate bearing capacities under downward and upward loads increase by about 14.03 % and 19.88 %; for per 100 mm increase in roof panel width, they decrease by about 27.14 % and 36.45 %; for per 200 mm increase in purlin spacing, they decrease by about 12.82 % and 5.01 %; for per 20 MPa increase in material strength, they increase by about 11.40 % and 2.24 %; for per 0.1 increase in friction coefficient, they increase by about 3.16 % and 9.01 %. Future studies can focus on the ultimate bearing capacities of SSMRSs under non-uniform loads with temporal and spatial fluctuation.

Numerical investigation of energy dissipation and vortex characteristics on the S-shaped region of a reversible pump-turbine

In order to meet the regulation needs of power system, the pump-turbine is prone to operate in the S-shaped region during frequent start-up, leading to unit vibration and grid connection failure. In this paper, the S characteristic experiment was carried out, and the entropy production, unstable flow and vortex structure under turbine, runaway, turbine breaking, reverse pump conditions with optimum guide vane opening are detailed analyzed. The relationship between the energy dissipation and flow field characteristics is clarified. The results show that the runner entropy production is the largest in all components, and the wall entropy production is greater than the fluctuating entropy production under turbine condition. With the decrease in discharge, the fluctuating entropy production and wall entropy production first increase and then decrease, reaching the maximum values in the runaway condition. The circumferential movement trend of water enhances, and forms circumferential flow in the vaneless region. The separation vortex formed on the blade suction surface extends from the blade inlet to the middle of the flow channel, inducing a high entropy production. Under the turbine braking condition, the tangential velocity increases rapidly in the vaneless region. The circumferential flow develops into water ring, blocking the water flows into the runner. Under the reverse pump condition, the water flows in the opposite direction, with negative tangential and streamwise velocities. The absolute flow angle becomes obtuse, and a large-scale reverse vortex is formed. The runner inlet is blocked by the water ring, and the flow channel is almost completely filled with the low-speed region. The proportion of the guide vanes entropy production reaches maximum. Unstable flow leads to the increase in vorticity. Separation vortex, bypassed vortex, and reverse flow vortex leads to an increase in VST, forming a high VST region at corresponding positions. Due to the rotational motion accompanying the development of separated vortex, it leads to the increase in CFT. In addition, the circumferential flow and water ring have higher tangential velocities, which can lead to high CFT regions.

Research on cyclic behavior of precast bridge piers with ECC-socket connections

Precast bridge piers with socket connections (SCPs) have been widely studied and certainly applied in recent years. To reduce the punching failure of socket connections, decrease their construction difficulty, and improve their application in complex environment areas, the embedment depth of SCPs needs to be decreased and the cyclic behavior of SCPs needs to be improved. In this study, engineered cementitious composite (ECC) was firstly introduced to the SCPs, a novel precast bridge piers with ECC-socket connections (SCEs) were proposed. Subsequently, 3D finite element models (FEMs) were established and validated against experimental results. Then, a detailed parametric study was conducted to investigate the cyclic behaviors of SCEs, including the embedment depth, ECC height, axial compression ratio, reinforcement ratio, and concrete compressive strength. Finally, a simplified calculation model was proposed to evaluate the bearing capacity and failure mode of SCEs. The results show that the shear damage of the embedded section is more severe for traditional shallow socket connections. Compared to traditional SCPs, the cyclic behavior of SCEs is better and influenced by ECC height and embedment depth, as well as axial compression ratio, reinforcement ratio, and concrete compressive strength. The simplified calculation model is suitable to evaluate the bearing capacity and failure mode of SCEs.

Timber-timber composite (TTC) joints made of short-supply chain beech: Push-out tests of inclined screw connectors

This paper presents the results of experimental investigations on six-layered, homogeneous glulam beams made of Italian short supply chain beech (Fagus sylvatica L.). At first, the beams were produced and mechanically characterized for bending, then, they were employed to realize timber-timber composite joints and tested under quasi-static monotonic loading. The test configurations were adopted to reproduce connections used in timber-to-timber composite structures for applications in new constructions. Outcomes in terms of connection stiffness, strength, static ductility and failure modes are presented and discussed. Moreover, the experimental stiffness were used to carry out analytical verification at the serviceability and ultimate limit states to extend the validity of the proposed screw and specimen’s configurations.

Experimental study on seismic behaviour of thick-flange steel beam to square CFST column joints with internal diaphragms

Composite structures made of concrete-filled steel tubular (CFST) columns and steel beams have gained widespread usage in high-rise and long-span structures, and beam-to-column joints strengthened by an internal diaphragm (ID) are expected to be efficient joint patterns. However, the thickness ratio (ηbc) limit of beam-to-column flanges is not considered sufficiently in current design codes and existing studies. Moreover, the previous tests rarely included specimens with a beam flange thickness reaching 40 mm. Thus, three joint specimens were designed and tested under cyclic loadings to further investigate the mechanical properties of the ID-type joints and guide engineering applications. The effects of the thickness ratio of the beam-to-column flange were mainly considered in this study. All beam flange thicknesses were 40 mm. Two failure modes were observed, including excessive development of beam plasticity and failure of local connections. Specifically, as the thickness of column walls decreased, the seismic behaviour, such as the resistance, stiffness and ductility of the joints, deteriorated obviously. Two out of three joint specimens satisfied the AISC requirements for composite special moment frames (C-SMF). Based on the test results, the limit value of the thickness ratio of beam-to-column flange (ηbc) has been proposed for design purposes.

An experimental study of cold-formed steel connections with screwed clip angle under tension and shear loads

This paper aims to investigate the performance of typical cold-formed steel (CFS) beam-to-beam connections between floor bearers and floor joists through a series of full-scale experiments. The investigated connections consisted of a lipped channel (floor joist), an unlipped channel (floor bearer), a thin-walled clip angle (connector), and a self-drilling screw (fastener). In this study, customised T-shaped and H-shaped CFS connection specimens were tested to examine the performance under tension and shear loads, respectively. Two sizes of self-drilling screws, 10 G and 14 G, were used with the selected load bearing clip angle. The fabricated connection specimens were subjected to displacement-controlled tension and shear loads. The experiments uncovered the ultimate connection strengths, load-displacement relationships, and failure mechanisms of the designed CFS connections under the applied loads. Moreover, the experimental tensile and shear strengths of the connections were compared with the strengths predicted by the standard design equations. It was found that the screw pullout on the anchored leg of the clip angle was the main mode of failure under the tensile load. On the other hand, two different failure modes—fracturing of 10 G screws or shear buckling of the cantilevered leg of the clip angle with 14 G screws—were observed in the H-shaped specimen under the applied shear load. Among the designed connection specimens, the maximum tensile load capacity was 30.86 kN and the maximum shear load capacity 88.15 kN. The standard design calculations predicted screw pullout failure under tension, while the shear bucking failure mode of the clip angle under shear load was overlooked.

Clustering Uniformity Methods for Energy Efficiency in Wireless Sensor Networks

The wireless sensors that make up a wireless sensor network (WSN) are randomly deployed in nature and cannot be artificially replaced when their batteries are depleted. Failure of communication connection between wireless sensors causes continuous connection attempts, which results in a lot of power dissipation and shortens the lifetime of the WSN. In this paper, we propose to extend the lifetime of WSNs by limiting the appropriate distance between the cluster head (CH) node and the communicating sensor nodes (SNs) so that a group of clusters of appropriate size can be formed on a two-dimensional plane. To equalize cluster size, sensor nodes with the shortest distance communicate with each other to form member nodes, and nodes with closer distances are bring together to form clusters. The simulation results show the improvement rate of cluster uniformity over the shortest distance-based clustering method for clustering based on the proposed cluster uniformity algorithm. The proposed method can improve the cluster uniformity of the network by about 20%. In addition, the power consumption of the proposed method is analyzed according to the difference in the density of sensor nodes in the cluster groups to examine the improvement in power consumption.

A Comprehensive Survey of Load Balancing Techniques in Multipath Energy-Consuming Routing Protocols for Wireless Ad hoc Networks in MANET

As technology progresses, networking undergoes continuous evolution to align with contemporary trends. Mobile Ad hoc Networks (MANETs) have emerged as a pivotal technology facilitating communication among mobile nodes sans a central administering node. MANETs find diverse applications spanning communication networks to battlefield scenarios. Nonetheless, MANETs encounter various challenges, including load balancing, energy efficiency, packet loss, and connection failures. Routing, among these challenges, assumes a pivotal role in defining network performance and connectivity capacity within MANETs. Moreover, the energy consumption of mobile nodes, often reliant on batteries with limited rechargeability, presents a significant concern in MANETs. This paper delves into diverse techniques devised to tackle the issues of energy efficiency and load balancing in MANETs. Additionally, it offers a comparative analysis to consolidate the survey findings. The outcomes of this study enrich our comprehension of energy-efficient and load-balanced routing protocols in MANETs, thereby facilitating the design and deployment of efficient networking solutions.