Transverse Connection Research Articles

Electrophysiologic characteristics and clinical correlation of right ventricular activation during left bundle branch area pacing (RV-LBBAP study)

BackgroundLeft bundle branch area pacing (LBBAP) results in a right bundle branch (RBB) delay pattern because of preexcitation of the left bundle. The mechanism of right ventricular (RV) activation during LBBAP is largely unknown. ObjectiveThe aim of the study was to analyze the electrophysiologic characteristics of RV activation by mapping the RBB during LBBAP and its clinical correlation. MethodsConsecutive patients who underwent successful LBBAP were included. RBB block, RV paced rhythm, and suboptimal intracardiac electrograms were excluded. LBBAP was performed with continuous recording of His bundle (HB) and RBB electrograms. RV activation was classified into 3 types based on the intracardiac electrogram: type I, RBB mediated; type II, transseptal activation; and type III, fusion pattern. ResultsOverall, 86 patients (94% left bundle branch pacing [LBBP]; 6% left ventricular septal pacing) were included. The mean age was 59.6 ± 12.8 years. Nonselective to selective capture transition was noted in 85% (n = 73). In patients with baseline normal QRS (n = 47), during selective LBBP (S-LBBP; n = 39), the most common pattern was type I (n = 35 [87%]), whereas during nonselective LBBP (NS-LBBP; n = 44), type III pattern (n = 40 [91%]) was common. In patients with left bundle branch block (n = 39), type III pattern was common during both S-LBBP and NS-LBBP. Type I pattern was noted only in patients with retrograde HB activation during S-LBBP. Left ventricular septal pacing showed type II activation in both groups. Patients without retrograde HB activation had higher left ventricular end-diastolic diameter, lower left ventricular ejection fraction, and prolonged HV interval compared with those with retrograde HB activation. ConclusionPhysiologic RBB-mediated (type I) activation of the right ventricle was the most common pattern observed during S-LBBP in patients with intact retrograde HB activation. Type III pattern was the most common pattern observed during NS-LBBP with fusion of multiple wavefronts from anterograde RBB activation, septal myocardial, and transverse interbundle connections.

Axial and eccentric compressive behavior of partially encased channel–concrete composite columns with bolted connections in modular buildings

This paper introduces a novel partially encased channel–concrete composite (PECC) column for modular buildings, aiming to eliminate the need for cast-in-place concrete and facilitate rapid assembly. The PECC column consists of two prefabricated modules connected by high-strength bolts. To evaluate the column's viability, six slender specimens—one bare steel column and five composite columns—were tested under axial and eccentric compression. Variables considered included the presence of concrete, the type of transverse connections, bolt spacing, and load eccentricity ratio. The compression performance of the PECC columns was analyzed by examining their failure patterns, load–deformation responses, initial stiffness, compressive capacity, and ductility. Test results revealed that the PECC columns failed due to global buckling, concrete spalling, and crushing. The bolted connections effectively prevented module separation, enabling the PECC columns to exhibit favorable compressive behavior. The reinforced concrete encased in the channel delayed the column's buckling failure, increasing its initial stiffness and compressive capacity by 98% and 198%, respectively. Using perforated steel plates instead of transverse links between the concrete and the channel enhanced the column's initial stiffness by 20% but had little effect on its compressive capacity. Reducing the bolt spacing improved the column's initial stiffness and compression resistance by 50% and 5%, respectively. Additionally, a finite element model for the PECC columns was developed and validated against test results. Finally, simplified formulas derived from Eurocode 4 were proposed to estimate the resistance of PECC columns under axial and eccentric compression.

Fatigue and Ultimate Strength Evaluation of GFRP-Reinforced, Laterally-Restrained, Full-Depth Precast Deck Panels with Developed UHPFRC-Filled Transverse Closure Strips

A depth precast deck panel (FDDP) is one element of the prefabricated bridge element and systems (PBES) that allows for quick un-shored assembly of the bridge deck on-site as part of the accelerated bridge construction (ABC) technology. This paper investigates the structural response of full-depth precast deck panels (FDDPs) constructed with new construction materials and connection details. FDDP is cast with normal strength concrete (NSC) and reinforced with high modulus (HM) glass fiber reinforced polymer (GFRP) ribbed bars. The panel-to-girder V-shape connections use the shear pockets to accommodate the clustering of the shear connectors. A novel transverse connection between panels has been developed, featuring three distinct female-to-female joint configurations, each with 175-mm projected GFRP bars extending from the FDDP into the closure strip, complemented by a female vertical shear key and filled with cementitious materials. The ultra-high performance fiber reinforced concrete (UHPFRC) was selectively used to joint-fill the 200-mm transverse joint between adjacent precast panels and the shear pockets connecting the panels to the supporting girders to ensure full shear interaction. Two actual-size FDDP specimens for each type of the three developed joints were erected to perform fatigue tests under the footprint of the Canadian Highway Bridge Design Code (CHBDC) truck wheel loading. The FDDP had a 200-mm thickness, 2500-mm width, and 2400-mm length in traffic direction; the rest was over braced steel twin girders. Two types of fatigue test were performed: incremental variable amplitude fatigue (VAF) loading and constant amplitude fatigue (CAF) loading, followed by monotonically loading the slab ultimate-to-collapse. It was observed that fatigue test results showed that the ultimate capacity of the slab under VAF loading or after 4 million cycles of CAF exceeded the factored design wheel load specified in the CHBDC. Also, the punching shear failure mode was dominant in all the tested FDDP specimens.

Reinforcement of Insufficient Transverse Connectivity in Prestressed Concrete Box Girder Bridges Using Concrete-Filled Steel Tube Trusses and Diaphragms: A Comparative Study

To address the issue of insufficient transverse connectivity in prestressed concrete box girder (PCB) bridges, this study investigates two transverse strengthening methods—installing diaphragms and utilizing concrete-filled steel tube trusses (CFSTTs). A finite element model was developed for a typical 30 m PCB bridge and was validated by on-site load test results for reliability. Based on the deflection and load distribution of PCB bridges before and after reinforcement, as well as the maximum stress and strain of the diaphragms and the CFSTTs, comparative analyses were conducted on diaphragms of different thicknesses and materials, as well as on CFSTTs of various strength grades. The results show that the addition of a transverse partition and CFSTTs can effectively improve the load distribution of the PCB bridge and reduce the maximum deflection of the girder, especially when using the CFSTT reinforcement method. The unique structural design improves the reinforcement effect of the material in the post-elastic stage. When using CFSTTs, increasing the steel tube wall strength significantly reduces the maximum deflection of the main girder. For example, using steel tubes with yield strengths of 235 MPa and 420 MPa filled with concrete of 50 MPa compressive strength reduced the maximum deflections by 15.32% and 24.55%, respectively, and improved the load distribution coefficients by up to 7.31% and 11.57%. Additionally, steel diaphragms demonstrated better reinforcement effects compared with concrete diaphragms. The load transverse distribution coefficients for the CFSTT-reinforced PCB bridge were calculated using the hinge plate (beam) and the rigid plate (beam) methods, showing minimal differences between the two approaches. The findings of this study provide valuable insights into the design of diaphragm and CFSTT reinforcement in PCB bridges, aiding in the selection of optimal reinforcement strategies.

Sliding connectors for cyclic construction of steel-UHPC composite truss arch bridges: design method and feasibility study

To break through the three major technical bottlenecks of traditional long-span arch bridges, which are excessive self-weight, high cost and difficult construction, a new steel-ultra high performance concrete (UHPC) composite truss arch bridge scheme and a matching cyclic construction method were proposed. The main arch can be divided into several times for closure from the inside out. Special transverse connection devices need to be installed between the arch ribs constructed with successive closures by step. The devices can not only ensure the stability of the arch ribs constructed subsequently, but also do not cause serious stress superposition on the already closed arch ribs. Therefore, sliding connectors for the cyclic construction of new arch bridges and the corresponding simplified modeling method were proposed in this paper. Subsequently, the working mechanism was analyzed, and the design method was proposed. Finally, the feasibility of sliding connectors and the correctness of the corresponding design method were verified by the experiment. The results indicate that it is necessary to install a transverse sleeve structure in the sliding connector, which plays a key role in transverse adjustment. The design of key dimensions in sliding connectors is controlled by the maximum vertical and longitudinal displacements of the inner arch. The outer arch could slide freely under the premise of ensuring stability, and the mechanical superposition response of the inner arch was relatively small. For the inner arch, the vertical displacement at the crown only increased by 10.94 %, and the maximum compressive stress in the UHPC arch ribs only increased by 16.3 %. The sliding connector also has the potential for further optimization to achieve smaller stress superposition.

Connection strength analysis for composite fuselage gate structures of civil aircraft

Civil aircraft boarding gate is an important channel for passengers to enter and exit the aircraft, and is also an important part of the aircraft structure, with the function of maintaining cockpit pressure. Traditional boarding doors are made of metal, and with the large number of composite materials used in the bearing structure of civil aircraft, composite boarding doors are also used in new civil aircraft. The strength of the connection inside the new composite boarding gate is related to the safety of passengers and crew. This paper focuses on the connection problem of the internal structure of composite boarding gate, aiming to analyze its connection strength under working conditions. This paper establishes a real finite element model of the boarding gate according to the loading condition and force transmission characteristics of the civil aircraft door and analyzes the connection strength of the structure such as the skin and the transverse and longitudinal beams, the skin and the side frame, the transverse and longitudinal beams connection, and the stop block in turn. The study shows that the strength of the connecting structures of the boarding gate designed by using composite materials is reasonable and can meet the service requirements of the boarding gate, thus demonstrating the rationality of the boarding gate structure designed with composite materials.

Experimental investigation and evaluation of shear performance of hollow slab beams strengthened by cavity grouting method

After 20 years of service, multiple web shear cracks were observed in 20 m-span prestressed concrete hollow slab beams. Shear enhancement is required to improve structural safety. To evaluate the strengthening effect of the new material on the hollow slab beam structure, fiber-reinforced cementitious composites (FRCC) were used to fill the cavities at the beam ends, and a comprehensive field load test was carried out on the shear-resistant performance of the actual bridge. The web principal stresses changed before and after strengthening under various working conditions, which were analyzed and compared with the performance of the traditional channel steel technique. The findings show that the web principal stresses are significantly reduced by more than 50 % after filling with FRCC, notably superior to the channel steel technique. In addition, both methods can reduce mid-span deflections by 10–20 %. The channel steel technique specifically enhances transverse connection capabilities. Furthermore, strain responses in the beam end sections were reduced by about 30–45 %. Finally, finite element simulations of single beam strengthening were also conducted to complement the experimental analysis. The simulation results show that the shear span ratio (λ), FRCC length and strand prestress loss remarkably impact the strengthening effect. The ultimate load capacity of the strengthened specimens decreases with the increase of λ and prestress loss and increases with the increase of FRCC length. In conclusion, the utilization of FRCC presents a superior alternative for shear enhancement in prestressed concrete hollow slab beams, offering substantial reductions in web principal stresses and enhanced structural performance compared to the traditional strengthening method.

ВАРІАНТИ ВИКОРИСТАННЯ ВЛАСТИВОСТІ УНІФІКАЦІЇ ПРИ ВИБОРІ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ РІШЕНЬ З’ЄДНАНЬ “МЕТАЛ+КОМПОЗИТ”

Possibility of unification property realization in application to variants of structural-technological solutions of “metal+composite” joints.It is drawn that this property is important for up-today vehicle engineering structures at different goals of its manufacturing. It is shown that there are three possible options can be revealed in metal-composite heterogenous joints realization: with monolithic, cylindrical and sheet transversal fastening connections.Possibility of application sheet transversal fastening elements produced on metal strips is considered exactly. Also, possibility of implementation strips of different materials and thickness is analyzed.The property of unification is most fully manifested at the stages of design, technological preparation of production and production itself. Variants of technological processes for manufacturing sheet fasteners on metal strips using stamping methods or laser cutting are proposed. An analysis of the advantages and disadvantages of these technical processes showed that the most rational method is stamping with bending.Options for route technical processes for forming transversal connections on metal tips using sheet reinforcing elements are proposed.Options for equipment are proposed, with the help of which serial production of teeth on metal strips is possible. It should be noted among these equipment options metal stamps for stamping teeth and using an electro-hydraulic device for bending them.Examples of implementation of design and technological solutions with sheet micro-elements in the manufacture of high-pressure vessels and in the strengthening of bolted joints are given.

Micro-macro performance evolution behavior of fine-grained porous asphalt mixture exposed to ultraviolet-water-heat-load coupling action

In the Yangtze River Delta of China, porous asphalt pavement is significantly affected by UV radiation, water, heat, and traffic load. Therefore, research on its long-term performance evolution behavior under multi-factor coupling effect contributes to conducting engineering practice. The key pavement performance evolution of fine-grained porous asphalt mixture (PA-13), using SBS/crumb rubber (CR) composite modifier or TPS modifier, with multiple void ratios was studied. The evolution of high-temperature stability, water stability, and meso-drainage performance of PA-13, among the simulated 5-year service process, was respectively evaluated by dynamic creep test, immersion Marshall test, CT scanning and three-dimensional reconstruction. The findings demonstrate that the negative impacts of coupled conditions are mainly concentrated in the later stage of service. Under cyclic effect, the good anti-permanent deformation ability of SBS/CR PA-13 helps to alleviate the attenuation of its void structure and permeability. Besides, the transverse connectivity of void is more obvious than the vertical connectivity throughout the entire service process. In general, SBS / CR PA-13 has better anti-attenuation ability than TPS PA-13 in high temperature stability, water stability and drainage performance, indicating SBS/CR porous asphalt mixture is more suitable for application in high temperature and rainy areas.

ANALISIS PENINGKATAN PERKERASAN LENTUR KE PERKERASAN KAKU PADA RUAS JALAN BUARAN - BENDANPETE STA 0+00 - 1+700 JEPARA JAWA TENGAH .

Afif Junaidhi, Nim 191230000357, Analysis of the improvement of flexible pavement to rigid pavement on the buaran - bendanpete sta 0+00 - 1+700 jepara central java road 2023., Yayan Adi Saputro, S.T., M.T., Nor Hidayati, S.T., M.T., Civil Engineering, Faculty of Science and Technology1, Nahdlatul Ulama University1 Jepara1. With roads, everyone can increase their mobility while fulfilling important activities. As time goes by and the length of service lasts, road conditions eventually decline, both in terms of service level and structural condition. The method used for analysis of rigid pavement on roads is the 2017 Pavement Design Manual1 Method and the method used for planning road surface drainage dimensions refers to SNI 03-3424-1994 concerning Procedures for Road Surface Drainage Planning. The results of rigid pavement planning research calculations using the 2017 Pavement Design Manual method resulted in a concrete plate thickness of 275 mm, a thin concrete layer1 (LMC) of 100 mm, a class A aggregate drainage layer of 150 mm. Connections in rigid pavement are divided into two, namely longitudinal connections with tie bars using Ø 161- 6001 threads, and transverse connections with dowels using plain reinforcement D 32 - 300. The material used is planned to use concrete. The calculation results obtained are that the channel base width is 65 cm, the wet channel height is 35 cm, and the guard height is 40 cm

A rare variant of mullerian agenesis: a case report and review of the literature

IntroductionMenstruation is a developmental milestone and usually marks healthy and normal pubertal changes in females. Menarche refers to the onset of first menstruation in a female. The causes of primary amenorrhea include outflow tract abnormalities, resistant endometrium, primary ovarian insufficiency, and disorders of the hypothalamus, pituitary, or other endocrine glands. A rare variant of mullerian agenesis, which warrants an individualized approach to management, is presented here.Case reportWe present here the case of a 25-year-old Indian female with pain in the lower abdomen and primary amenorrhea. After a thorough history, clinical examination, imaging, and diagnostic laparoscopy, two small uteri, a blind upper half vagina, bilateral polycystic ovaries, and a blind transverse connection between the two uteri—a horseshoe band cervix—were detected, which confirmed the diagnosis of mullerian agenesis. There was evidence of adenomyosis in the mullerian duct element. This is a rare form of Müllerian abnormality with an unusual presentation.ConclusionMullerian agenesis is the most common cause of primary amenorrhea with well-developed secondary sexual characteristics. There are various forms of mullerian agenesis. Most of the cases are managed by a multidisciplinary team. Rare variants warrant an individualized approach to management.

Fatigue performance analysis of precast segmental assembled concrete beams

In recent years, assembled bridges have become widely utilized in bridge construction, raising concerns about durability-related bridge diseases over time. These issues significantly impact the fatigue life of assembled bridges, necessitating an in-depth exploration of their fatigue performance. While existing research primarily concentrates on the transverse connection of multiple longitudinal beams, there is a notable dearth of studies on longitudinal precast segmental assembled bridges. This paper addresses this gap by establishing a fatigue benchmark finite element model for segmental assembled concrete beams, building upon existing experiments. The study employs numerical simulation to analyze the entire fatigue process, examining stress distribution, damage development, and considering the influence of reinforcement corrosion. Furthermore, a fatigue life prediction method, based on fatigue residual strength (R), is proposed for predicting the fatigue life (N) of concrete in precast segmental assembled beams. Results reveal that prestressed and ordinary reinforcements experience increasing stress with loading cycles, peaking around 100,000 cycles. Throughout fatigue loading, compressive stress in concrete remains low, preventing fatigue compression failure. However, tensile stress near joints gradually rises, initiating cracks at the mid-span beam’s bottom. With continued cyclic loading, these cracks propagate towards the loading point. The upper and lower limits of fatigue life predicted by the fatigue life prediction method closely align with the compressive fatigue test values of concrete, proposed fatigue life prediction method is efficient and accurate.

Finite element analysis of different pedicle screw internal fixations for first lumbar vertebral fracture in different sports conditions.

Lumbar fractures are the most common spinal injuries, and surgery is required for severe fracture. This study aimed to investigate the variations in motion and stress in varying states of activity after minimally invasive and traditional open pedicle screw placement for L1 vertebral fracture stabilization. We studied a male volunteer (26 years old) with no history of chronic back pain or lumbar spine trauma. We used the finite element method for this investigation. Using finite element software, we created a three-dimensional model of L1 vertebral compression fracture. We also constructed models for four percutaneous pedicle screws spanning the fractured vertebra and four screws traversing the damaged vertebra with transverse fixation. In all three-dimensional movement directions, the open pedicle fixation system experienced maximum stress higher than its percutaneous counterpart. With axial spinal rotation, von Mises stress on the traditional open pedicle screw was considerably lower than that with percutaneous pedicle fixation, but peak stress was elevated at the transverse connection. Traditional open pedicle fixation displayed less maximum displacement than percutaneous pedicle internal fixation. During axial spinal movements, high peak stress is observed at the transverse connection. Patients should avoid excessive axial rotation of the spine during recovery.

Magnetoinduced spin Nernst effect in topological nodal-line semimetals

The spin Nernst effect (SNE) of a topological nodal-line semimetals (TNLSMs) nanowire in a four-terminal cross-bar device is studied. Based on the nonequilibrium Green’s function method combining with the tight-binding Hamiltonian, the spin Nernst coefficients Ns3z, Ns3x and Ns3y of the two thermal transport models (kz-y case and kx-y case) under a perpendicular magnetic field are obtained. The traditional SNE describes the transverse voltage and spin current caused by the longitudinal thermal gradient. The transverse spin current is generated by the spin–orbit interaction rather than the perpendicular magnetic field. Here we find that the spin Nernst coefficients are equal to zero at the zero-magnetic field, but have finite values for non-zero magnetic fields in TNLSMs. The spin Nernst coefficient is closely related to the strength of the magnetic field and temperature. With the increase of the magnetic field strength, the peak height of the spin Nernst coefficient increases. These results indicate that the SNE is induced by the perpendicular magnetic field in the present TNLSMs system, which can be considered as an anomalous spin Nernst phenomenon. In addition, we find that Ns3z displays a series of peaks when the transmission coefficient TLR jumps from one integer plateau to another, and the spin Nernst coefficient Ns3i (i=x,y,z) is an odd function of the Fermi energy EF with Ns3z/x/y(−EF)=−Ns3z/x/y(EF) in connection mode kz-y. For the kx-y connection mode, due to the presence of the mass term m opening the energy gap, a sudden jump of the transmission coefficient TLR in the vicinity of the energy gap edge causes a very larger peak for the spin Nernst coefficient Ns3z/x/y, and the symmetrical properties of the spin Nernst coefficient Ns3z/x/y are completely broken in the strong magnetic field. These results indicate that the spin Nernst coefficient in TNLSMs strongly depends on the thermal gradient direction and the transverse lead connection direction. The spin Nernst coefficient in TNLSMs has strongly spatial anisotropy, which can be used as the characterization of the experimental detection of TNLSMs.

Repair strategies and objectives of the Autostrada dei Parchi motorway structures

The Autostrada dei Parchi, comprising the A24 and A25 motorways, is the key infrastructure of Central Italy, linking the West- and East Coasts of the Country, and is located mainly within the Region Abruzzo. It represents the only effective transverse connection, as roads and railway are obsolete and allow for very low capacity.A24+A25 contain a remarkable amount of structural works and run in a quite unfavourable environment, practically all in mountain range, with large temperature excursions, frequent rain/snow fall and high seismicity. Owned and managed by the State, they were designed and built starting in the sixties, at a time when neither professionals nor codes of practice were accounting for durability, seismic engineering was primordial and structural standards, referring to actions, zoning as well as to specifications, were rather poor.In year 2003, Strada dei Parchi SpA (SdP), a private company, took them in charge as a State Concession, through a European tender, inheriting the maintenance problems when structures already needed deep repair and strengthening, also according to new specifications on road, seismic, durability and strategic infrastructure performance.Providing general maintenance and retrofit requires important investments, released by the State on proposal of SdP, as they are far to be covered by the tolls paid by motorway users. Thus, the task is met within complex procedures and timing.Within this framework, the company fulfils the task with a proactive management of the works, based on the compliance with the standards and the search for overall sustainability. Priorities are: first, those linked to users’ safety; then to durability, according to the data of a permanent monitoring and the optimization of repair or rebuilt, before damage may affect the structural reliability. All this coordinated with the undelayable maintenance of the road platform and with the effects of “spot events”.

Performance monitoring of assembled beam bridges using displacement spectrum similarity measure

The assembled beam bridge is a widespread construction, with transverse connections uniting precast beams to jointly support loads. These connections, while crucial, are the most vulnerable elements in such structures. Therefore, the development of an effective index for continuous condition assessment remains the cornerstone of structural health monitoring. The Displacement Spectrum Similarity Measure index, as per ideal conditions in numerical simulations, has shown insensitivity to short-term vehicle loads and sensitivity to transverse connection stiffness. This study extends its scope to address potential real-world interference factors, including measurement errors and deck pavement damage. Specifically, we introduce Gaussian white noise to simulate measurement errors and incorporate additional vehicle loads to emulate the impact of pavement damage. Numerical simulations confirm the robustness of the index against these challenges. Additionally, a real-time index extraction scheme is proposed and implemented on an operational bridge. The results reveal a close alignment between the transverse connection condition assessed by the index and the findings obtained through on-site surveys, thereby substantiating the viability and effectiveness of the index for real-world engineering contexts.

Numerical design calculation of the high-strength steel welds

This study focused on the design of fillet welds fabricated using high-strength steel (HSS). Herein, we present a numerical design calculation (NDC) method for assessing weld strength using the regular inclined shell element model (RISEM) in the finite element method (FEM). The NDC uses the FEM to design joints according to standardised procedures. The inclined shell element in the RISEM represents the geometry and stiffness of the welds, which controls the stresses in the plane. We recommend using a common inclined shell element with rigid links to accurately represent the geometry and rigidity of fillet welds. A new strength criterion is proposed based on the stresses on the inclined shell element, using the maximum equivalent stress as an indicator. An experiment was conducted on the transverse fillet lap-welded connection from the S700 MC Plus steel plate and OK AristoRod 13.12 electrode at room temperature. The deformation capacity of the welded connection was measured via a non-contact process using the digital image correlation (DIC) technique. This method was validated by comparing the RISEM and test results using finite element (FE) simulations. Additionally, the weld resistance computed from the analytical model of prEN 1993–1–8:2020 was in good agreement.

Computer assisted proof of homoclinic chaos in the spatial equilateral restricted four-body problem

We develop constructive, computer assisted arguments for proving the existence of transverse homoclinic connections for hyperbolic periodic orbits in Hamiltonian systems. These arguments are applied at a number of non-perturbative parameter and energy values in the spatial equilateral circular restricted four-body problem: a six dimensional vector field. The idea is to formulate the desired connecting orbits as solutions of certain two point boundary value problems for orbit segments which originate and terminate on the local stable/unstable manifolds attached to a periodic orbit. These boundary value problems are studied via a Newton-Kantorovich argument in an appropriate Cartesian product of Banach algebras of rapidly decaying sequences of Chebyshev coefficients. Perhaps the most delicate part of the problem is controlling the boundary conditions, which must lie on the local stable/unstable manifolds of the periodic orbit. For this portion of the problem we use a parameterization method to develop Fourier-Taylor approximations equipped with mathematically rigorous a-posteriori error bounds. This requires validated computation of a finite number of Fourier-Taylor coefficients via Newton-Kantorovich arguments in appropriate Cartesian product of rapidly decaying sequences of Fourier coefficients, followed by a fixed point argument to bound the tail terms of the Taylor expansion. After some geometric considerations in the energy manifold, transversality of the connection follows as a direct consequence of the Newton-Kantorovich argument.

Deformation behaviour of high‐strength steel welds using DIC

AbstractThis paper focuses on the deformation and strength behaviour of high‐strength steel (HSS) transverse fillet welds. The behaviour of six lap‐welded fillet joints made of high‐strength steels (HSSs) is investigated under tension load through experiment. Due to some weaknesses in the deformation measurement using traditional techniques, the digital image correlation technique (DIC) is used to measure the deformation of transverse fillet weld connections. The development of the deformation on the specimen throughout the loading process was analysed using DIC measurement. The deformation of transverse fillet lap‐welded connections from HSS is always less than 1 mm. The strength calculated from the weld's fracture surface area shows better results than the theoretical weld area because it provides the real strength of the weld. In most cases, the weld failure did not occur along the throat section. Moreover, it is confirmed that the analytical models offered by prEN 1993‐1‐8:2020 are conservative for all the specimens.

Hamiltonian structure of rational isomonodromic deformation systems

The Hamiltonian approach to isomonodromic deformation systems is extended to include generic rational covariant derivative operators on the Riemann sphere with irregular singularities of arbitrary Poincaré rank. The space of rational connections with given pole degrees carries a natural Poisson structure corresponding to the standard classical rational R-matrix structure on the dual space L*gl(r) of the loop algebra Lgl(r). Nonautonomous isomonodromic counterparts of isospectral systems generated by spectral invariants are obtained by identifying deformation parameters as Casimir elements on the phase space. These are shown to coincide with higher Birkhoff invariants determining local asymptotics near to irregular singular points, together with the pole loci. Pairs consisting of Birkhoff invariants, together with the corresponding dual spectral invariant Hamiltonians, appear as “mirror images” matching, at each pole, the negative power coefficients in the principal part of the Laurent expansion of the fundamental meromorphic differential on the associated spectral curve with the corresponding positive power terms in the analytic part. Infinitesimal isomonodromic deformations are shown to be generated by the sum of the Hamiltonian vector field and an explicit derivative vector field that is transversal to the symplectic foliation. The Casimir elements serve as coordinates complementing those along the symplectic leaves, defining a local symplectomorphism between them. The explicit derivative vector fields preserve the Poisson structure and define a flat transversal connection, spanning an integrable distribution whose leaves may be identified as the orbits of a free Abelian local group action. The projection of infinitesimal isomonodromic deformation vector fields to the quotient manifold under this action gives commuting Hamiltonian vector fields corresponding to the spectral invariants dual to the Birkhoff invariants and the pole loci.