The Leibniz University Hannover, long form in German Gottfried Wilhelm Leibniz Universität Hannover, is a public research university located in Hanover, Germany. Founded on 2 May 1831, it is one of the largest and oldest science and technology universities in Germany. In the 2014/15 school year it enrolled 25,688 students, of which 2,121 were from foreign countries. It has nine faculties which offer 190 full and part degree programs in 38 fields of study. It was named University of Hannover in 1978. In 2006, it was named after Gottfried Wilhelm Leibniz, the 18th century mathematician and philosopher. In 2018, Leibniz University Hannover was adopted as the official English name.Leibniz University Hannover is a member of TU9, an association of the nine leading Institutes of Technology in Germany. It is also a member of the Conference of European Schools for Advanced Engineering Education and Research (CESAER), a non-profit association of leading engineering universities in Europe. The university sponsors the German National Library of Science and Technology (TIB), the largest science and technology library in the world.
In this paper, we study a novel approach to asynchronous hyperproperties by reconsidering the foundations of temporal team semantics. We consider three logics: , and , which are obtained by adding quantification over so-called time evaluation functions controlling the asynchronous progress of traces. We then relate synchronous to our new logics and show how it can be embedded into them. We show that the model checking problem for with Boolean disjunctions is highly undecidable by encoding recurrent computations of non-deterministic 2-counter machines. Finally, we present a translation from to Alternating Asynchronous Büchi Automata and obtain decidability results for the path checking problem as well as restricted variants of the model checking and satisfiability problems.
Structural global reliability evaluation under dynamic excitations often involves highly complex failure boundaries and multiple interacting limit states, resulting in prohibitively high computational cost when using traditional probabilistic integration methods. This paper aims to address this challenge by proposing an enhanced computational framework based on the decoupled multi-dimensional probability density evolution method (M-PDEM) combined with an extended absorbing boundary condition strategy. Specifically, the proposed framework achieves both theoretical and numerical decoupling by transforming the original high-dimensional integration in the space of basic random variables into a series of one-dimensional generalized density evolution equations (GDEEs) defined in the response space. Rigorous theoretical conditions are established to guarantee decoupling feasibility, requiring separability of the residual joint probability density function (PDF) and factorization of the failure domain into finite unions or differences of hyper-rectangular sets. A robust three-step numerical implementation is derived, incorporating (i) discrepancy-optimized probabilistic space partitioning, (ii) finite-volume solution of the GDEEs using a weighted essentially non-oscillatory (FV-WENO) scheme, and (iii) rule-based aggregation of reliability metrics for AND-, OR-, and general Boolean combinations of correlated limit-state events. Numerical examples, including a single-degree-of-freedom (SDOF) oscillator with AND-type limit states, an Euler-Bernoulli beam with OR-type limit states failure, and a nonlinear concrete frame under seismic loads with a general limit-state specification, validate that the proposed methodology substantially reduces computational complexity while preserving high accuracy (with relative errors consistently below 1%) at a moderate computational cost, with the accuracy controlled by the number of representative points used in the probabilistic-space partition. Overall, this enhanced decoupled M-PDEM with absorbing boundaries provides a unified, efficient, and accurate solution to structural dynamic reliability problems involving multiple and potentially coupled failure criteria.
Fractured rock masses exhibit complex deformation and failure behavior governed by the interaction between stress redistribution and evolving internal structure. However, existing numerical approaches struggle to simultaneously represent diffuse damage within intact material and discrete fracture along structural interfaces. To address this limitation, this study proposes a coupled finite–discrete element method and phase-field method (FDEM–PFM) framework that integrates bulk damage evolution with interfacial decohesion and block interaction in a unified formulation. Hereby, the phase-field method describes mesh-independent crack initiation and diffuse damage in the bulk, while the finite-discrete element method captures interface opening, sliding, contact, and post-failure block kinematics. This coupling enables a physically consistent transition from continuum damage to discrete fracture, overcoming the limitations of conventional approaches that treat these mechanisms separately. The predictive capability of the model is first assessed through validation against three loading configurations: uniaxial compression, direct shear, and biaxial compression under varying confinement. The framework accurately reproduces stress–strain responses, failure patterns, and pressure-dependent strength, demonstrating its ability to capture bulk damage, shear-dominated interface failure, and confinement effects within a single modeling approach. Building on this validation, a parametric study is conducted to investigate the influence of interfacial stiffness on stress transfer, energy partitioning, and failure mode transition. The results reveal three distinct regimes. At high stiffness, deformation is governed by bulk damage in a stress-controlled regime. At intermediate stiffness, bulk damage and interface failure interact, producing a coupled structure–stress response. At low stiffness, deformation localizes near interfaces, leading to a strain-controlled regime dominated by phase-field damage. These findings demonstrate that interfacial stiffness governs the transition between fundamentally different failure mechanisms and plays a central role in the macroscopic response of fractured rock. The proposed FDEM–PFM framework provides a robust and physically consistent tool for modeling structure–stress interactions, bridging the gap between continuum damage mechanics and discrete fracture dynamics.
High-definition (HD) vector maps are essential to trajectory forecasting, yet existing methods often use them only as passive context and remain dependent on identity-consistent tracking histories. We propose a unified geometry-centric forecasting framework that treats road-space geometry as an active computational substrate for both future prediction and history recovery under tracking-available and no-tracking conditions. The framework uses a common road-space representation and topology-guided decoupled decoder architecture across both settings, while differing only in how motion history is constructed. With reliable tracking, agent history is incrementally aggregated across shifting local frames for efficient streaming inference. Without tracking, frame-wise detections are projected into lane-space occupancy memories, from which target-specific history is recovered through geometry-conditioned querying. The decoder then generates topology-consistent motion intents and realizes them as final trajectories using surrounding-agent interactions. Experiments on Argoverse 2 (AV2), Argoverse 1 (AV1), and the Waymo Open Motion Dataset (WOMD) show that the proposed framework achieves competitive performance under reliable tracking and supports low-latency streaming inference, reaching 44.32ms per frame with pre-encoded maps. Under no-tracking conditions, the occupancy-based pathway preserves most of the tracking-available performance on the primary K=6 metrics, with relative increases in minFDE6, minADE6, and MR6 limited to 6%–8% on AV2 and below 3% on AV1 and WOMD. Additional validation on real sensor data with annotated detections and a tracking-by-detection association pipeline shows that the occupancy-based pathway remains robust to tracking identity errors, whereas identity-dependent methods degrade substantially. These results demonstrate that actively exploiting road-space geometry can substantially reduce trajectory forecasting’s reliance on upstream tracking.
Abstract This study proposes a novel bonded straight iron-based shape memory alloy (Fe-SMA) plate system using hybrid anchorage for the shear strengthening of reinforced concrete (RC) T-beams and presents a comprehensive experimental evaluation of its structural performance. Unlike existing Fe-SMA shear-strengthening configurations that rely on mechanically complex anchorage or exhibit limited prestress transfer, the proposed hybrid-anchored configuration enables the reliable application of active prestressing without hydraulic anchorages while allowing flexible vertical or diagonal strengthening layouts. Fifteen specimens were tested under three-point bending to evaluate the effects of shear-span ratio ( λ = 1.0, 1.5, 2.0), activation temperature (150°C, 250°C), Fe-SMA inclination angle ( β = 90°, 45°), and bonding condition. The results demonstrate that the proposed system significantly improves the shear behavior of RC T-beams. Compared with unstrengthened specimens, activated Fe-SMA plates increased the maximum shear capacity by up to 43%, reduced internal stirrup stress, and enhanced postcracking stiffness by approximately 30%. The system also significantly improved crack-control performance, reducing the maximum diagonal crack width by more than 60% and increasing the initial cracking shear force by up to 116%, which effectively delayed crack propagation and mitigated brittle failure. Diagonal strengthening ( β = 45°), oriented perpendicular to the principal tensile stress direction, produced more uniform crack distributions and superior confinement. Bonded configurations provided additional advantages, ensuring a more uniform transfer of self-prestress and achieving shear capacity increases up to three times greater than those in unbonded specimens. The theoretical values closely matched the experimental results, confirming that the contribution of the activated Fe-SMA exceeded that of the stirrups by more than a factor of 2. Overall, the proposed bonded Fe-SMA strengthening system offers active crack control, substantial shear performance enhancement, and ease of installation, providing a practical and durable solution for upgrading existing concrete bridges and structural members.
