Abstract: Recent entity and relation extraction works focus on investigating how to obtain a better span representation from the pre-trained encoder. However, a major limitation of existing works is that they ignore the interrelation between spans (pairs). In this work, we propose a novel span representation approach, named Packed Levitated Markers (PL-Marker), to consider the interrelation between the spans (pairs) by strategically packing the markers in the encoder. In particular, we propose a neighborhood-oriented packing strategy, which considers the neighbor spans integrally to better model the entity boundary information. Furthermore, for those more complicated span pair classification tasks, we design a subject-oriented packing strategy, which packs each subject and all its objects to model the interrelation between the same-subject span pairs. The experimental results show that, with the enhanced marker feature, our model advances baselines on six NER benchmarks, and obtains a 4.1%-4.3% strict relation F1 improvement with higher speed over previous state-of-the-art models on ACE04 and ACE05. Our code and models are publicly available at https://github.com/thunlp/PL-Marker

Abstract: In this paper, the hysteresis performance of an assembled bolt-connected buckling-restrained brace (AB-BRB) is experimentally discussed by a parametric study, and five changing factors are selected to analyze the corresponding influence in static behaviors. The deformation modes of core plates are compared, the critical points of hysteresis curves are analyzed, and six static indices for hysteresis responses are assessed. Afterwards, the seismic evaluations of AB-BRB applied into structural retrofit are conducted, based on an aged 3-span-3-story and 5-span-10-story reinforced concrete frame. The numerical model is established and verified for both local AB-BRB and integral frame structure, and the simulation details as well as selection strategies are suggested during the process. The nonlinear time history analyses, incremental dynamic analyses and seismic fragility analyses are all performed, and three dynamic indices, three limit states, three fractile probabilities, three comparing conditions and two intensity levels are well discussed for assessment, before and after retrofitting, respectively. In general, the influences of shell thickness are less than shell height, and a larger gap clearance may transfer the deformation pattern into end-wave modes. Less bolt number may affect the assembly operation and global buckling capacity, which proves the effectiveness of bolt design equation in a sense. Bolt number contributes greatly to the macro hysteresis trends, and less tightening bolts may weaken the retraining property, accompanied with the bolt-slippage occurrence under huge vertical thrusts transferred from core plates. The seismic indices for each ground motion are below limitations and are more uniform with less discreteness after retrofitting with AB-BRB. The structural capacity can be guaranteed safely, and the damage degree of the integrated system can be controlled with the application of AB-BRB, illustrating the apparent retrofitting superiority in performance enhancement and providing reference for the follow-up research of AB-BRB in the earthquake-prone areas.

Abstract: Span-based methods with the neural networks backbone have great potential for the nested named entity recognition (NER) problem. However, they face problems such as degenerating when positive instances and negative instances largely overlap. Besides, the generalization ability matters a lot in nested NER, as a large proportion of entities in the test set hardly appear in the training set. In this work, we try to improve the span representation by utilizing retrieval-based span-level graphs, connecting spans and entities in the training data based on n-gram features. Specifically, we build the entity-entity graph and span-entity graph globally based on n-gram similarity to integrate the information of similar neighbor entities into the span representation. To evaluate our method, we conduct experiments on three common nested NER datasets, ACE2004, ACE2005, and GENIA datasets. Experimental results show that our method achieves general improvements on all three benchmarks (+0.30 \sim 0.85 micro-F1), and obtains special superiority on low frequency entities (+0.56 \sim 2.08 recall).

Abstract: Sodium/potassium-ion batteries (SIBs/PIBs) are supposed to replace the conventional lithium-ion batteries (LIBs) in the near future in view of their lower cost and abundant reserves of sodium/potassium resources. Nowadays, it...

Abstract: Most existing reading comprehension datasets focus on single-span answers, which can be extracted as a single contiguous span from a given text passage. Multi-span questions, i.e., questions whose answer is a series of multiple discontiguous spans in the text, are common real life but are less studied. In this paper, we present MultiSpanQA, a new dataset that focuses on multi-span questions. Raw questions and contexts are extracted from the Natural Questions dataset. After multi-span re-annotation, MultiSpanQA consists of over a total of 6,000 multi-span questions in the basic version, and over 19,000 examples with unanswerable questions, and questions with single-, and multi-span answers in the expanded version. We introduce new metrics for the purposes of multi-span question answering evaluation, and establish several baselines using advanced models. Finally, we propose a new model which beats all baselines and achieves state-of-the-art on our dataset.

Abstract: Synthetic Aperture Radar Interferometry (InSAR) using satellite data is revealing a promising tool for monitoring long-term deformation phenomena in critical infrastructural systems. Nevertheless, its use in structural engineering is still quite limited and a general understanding of its potential is still missing, especially when dealing with bridge structures for which specific methods of data processing and displacement assessment with error quantification need to be developed, accounting for the type of deformation phenomena and for the orientation of the bridge. In order to partly fill this research gap, this paper proposes a post-processing methodology to derive two-dimensional displacement configurations of multi-span bridges with properly defined error bounds, using both ascending and descending Synthetic Aperture Radar acquisitions. In order to obtain an engineering meaningful estimate of the uncertainties affecting the reconstructed bridge deformations, both random and systematic errors are quantified, accounting for the orientation of the bridge with respect to the Line-Of-Sights of the satellites, the hypothesized deformation plane and the accuracy of InSAR measurements. The proposed procedure has been applied to the illustrative case study of the Albiano-Magra Bridge in Italy, collapsed on 8 April 2020. The results, referred to the monitoring period 2015–2020, demonstrate the effectiveness of the proposed method in supporting engineering assessments. In particular, an initially temperature-induced stationary deformation phenomenon has been observed, with all spans moving upwards or downwards during summer and winter. Afterwards, displacements of increasing amplitude for two side spans have been observed during the three years preceding the failure, providing information on the possible cause of collapse.

Abstract: Nested entities are observed in many domains due to their compositionality, which cannot be easily recognized by the widely-used sequence labeling framework.A natural solution is to treat the task as a span classification problem.To learn better span representation and increase classification performance, it is crucial to effectively integrate heterogeneous factors including inside tokens, boundaries, labels, and related spans which could be contributing to nested entities recognition.To fuse these heterogeneous factors, we propose a novel triaffine mechanism including triaffine attention and scoring.Triaffine attention uses boundaries and labels as queries and uses inside tokens and related spans as keys and values for span representations.Triaffine scoring interacts with boundaries and span representations for classification.Experiments show that our proposed method outperforms previous span-based methods, achieves the state-of-the-art F1 scores on nested NER datasets GENIA and KBP2017, and shows comparable results on ACE2004 and ACE2005.

Abstract: Shear span ratio (SSR) is a key factor affecting the structural and seismic behavior of shear walls. Existing experimental studies on the seismic behavior of shear walls with SSR less than 1.0 are limited. In order to study the seismic behavior of squat reinforced concrete (RC) shear walls, 16 specimens (of which four specimens were subjected to coupled tension-shear force) with SSR of 0.5, 0.75, and 1.0 were fabricated and subjected to horizontal low-cycle repeated loading tests. The parameters considered in the test included the SSR, axial load ratio (ALR), and horizontal reinforcement ratio (HRR). The seismic behavior of the 16 squat RC shear wall specimens was investigated by analyzing their failure modes, hysteretic behaviors, and energy dissipation capacities. This study also assessed the validity of shear strength capacity formulae for shear walls with low SSR adopted in the design codes used currently in China, America, Canada and Europe. Five failure modes were observed in the 16 specimens, namely, diagonal compression-sliding (DCS) failure, diagonal compression (DC) failure, shear-bending (SB) failure, shear sliding (SS) failure, and tensile shear (TS) failure. For the specimens under compression, the failure mode of the specimens changed from shear failure to shear-bending failure with the increase in SSR. Also, the shear strength capacity was significantly reduced as SSR increased, while the deformation capacity and energy dissipation capacity increased significantly. The specimens under tension with SSR of 0.5 suffered TS failure. Vertical tension significantly decreased the shear strength capacity and energy dissipation capacity of the shear walls, however their ductility factor and ultimate displacement increased. The increase in ALR from 0.3 to 0.5 enhanced the shear strength capacity of the shear walls but the energy dissipation capacity reduced. With the increase in HRR, the shear strength capacity and energy dissipation capacity of the shear walls improved slightly. The shear strength capacities of shear walls assessed according to the four design codes were all conservative for the specimens suffering DC failure and DCS failure, while the opposite was true for the specimens with TS failure. For the specimens suffering SB failure, only the ACI 318-19 calculation results were not conservative compared to the test results.

Abstract: Potential harm is understudied and largely overlooked

Abstract: Aspect Sentiment Triplet Extraction (ASTE)is a new fine-grained sentiment analysis task that aims to extract triplets of aspect terms, sentiments, and opinion terms from review sentences.Recently, span-level models achieve gratifying results on ASTE task by taking advantage of the predictions of all possible spans.Since all possible spans significantly increases the number of potential aspect and opinion candidates, it is crucial and challenging to efficiently extract the triplet elements among them.In this paper, we present a span-level bidirectional network which utilizes all possible spans as input and extracts triplets from spans bidirectionally.Specifically, we devise both the aspect decoder and opinion decoder to decode the span representations and extract triples from aspect-to-opinion and opinion-to-aspect directions.With these two decoders complementing with each other, the whole network can extract triplets from spans more comprehensively.Moreover, considering that mutual exclusion cannot be guaranteed between the spans, we design a similar span separation loss to facilitate the downstream task of distinguishing the correct span by expanding the KL divergence of similar spans during the training process; in the inference process, we adopt an inference strategy to remove conflicting triplets from the results base on their confidence scores.Experimental results show that our framework not only significantly outperforms state-of-the-art methods, but achieves better performance in predicting triplets with multi-token entities and extracting triplets in sentences contain multitriplets 1 .

Abstract: Stay cables in cable-stayed bridges are subjected to various types of dynamic excitation mechanisms under environmental loads. The excited vibrations can have a large amplitude because of low vibration frequencies and small inherent damping of cables. As cables become longer (the longest cables are around 600 m in cable-stayed bridges with a main span of 1000 m), more modes are vulnerable to wind and rain-wind induced vibrations, posing challenges to vibration mitigation. This paper presents a comprehensive review of recent advances in stay cable vibration mitigation, including theoretical modeling of cable damping system and techniques for enhancing multimode damping. Recent results on cable damping measurements, understanding of cable vibrations, and relevant aerodynamic countermeasures are also recalled. The reflections can provide guidance for cable vibration control design of cable-supported bridges and for the maintenance/upgrade of cable vibration mitigation system of existing bridges.

Abstract: We propose a novel monitoring that enables to localize PDL in multi-span transmission using only Rx-side DSP and experimentally demonstrate sufficient accuracy within error of 1km with eighty-two polarization combinations in three-span, 180-km transmission line.

Abstract: Long-span cable-supported bridge is one of crucial transportation infrastructures. Structural health monitoring (SHM) system that is used to assess structural service conditions and detect early damage has drawn a growing attention in engineering structural society. It provides a real-time monitoring of various structural changes under operational and extreme conditions. Yangluo Bridge over Yangtze River in Wuhan city of China is a 1280 m central span suspension bridge with an orthotropic steel box girder. Taking the SHM system of Yangluo Yangtze River Bridge as an example, this paper presents an implementation of SHM system on the bridge in terms of sensor layout, data acquisition strategy, data transmission, data processing, and abnormal alarm framework. With such an SHM system, the typical monitoring results are demonstrated such as operational environments, loadings, structural deformation, strains, dynamic properties, and structural responses. The SHM system of Yangluo Yangtze River Bridge is continuously gathering data and monitoring structural behavior. It is anticipated that it will provide either scientific or technological supports to the service comfort and safety of the bridge.

Abstract: Displacement is an essential indicator of the functioning and safety of long-span cable-supported bridges under operational conditions. However, displacement estimation is challenging as these bridges are simultaneously subjected to various loading conditions such as temperature, wind, and vehicles. This article investigates an approach for estimating bridge displacement responses under multiple loads using a residual autoencoder model. Monitoring data of a cable-stayed bridge are collected to validate the proposed approach, including comprehensive measurements of the various loads and the displacement responses. Characteristics of temperature, wind, and vehicle loads are taken as the input, and the displacement responses at the mid-span of the main girder and top of the two pylons are taken as the output. The results showed the effectiveness of the proposed approach with an accuracy higher than 95%, which clearly outperformed other models such as long short-term memory networks in accuracy and efficiency. The effects of different types of loads are also investigated, and the wind load is found to be the most influential. Furthermore, multistep ahead prediction is carried out using the proposed approach, and good accuracy is achieved even 5 min ahead. The proposed approach can shed light on early warning of the malfunction of the bridge.

Abstract: The dynamic response characteristics, including maximum jump height and unbalanced tension, of isolated-span transmission lines after ice-shedding are investigated by means of experiments. A reduced-scale modelling method for ice-shedding from conductor lines is presented and verified with numerical simulations and full-scale test results in the literature. A parameter study on dynamic responses of isolated-span conductors under three ice-shedding scenarios, including whole span ice-shedding, partial ice-shedding and unzipping ice-shedding, is carried out by means of reduced-scale modelling tests. The effects of these parameters on the maximum jump height at typical positions and unbalanced tension in the tension tower are obtained. It is observed that the partial ice-shedding scenario may be the worst situation for electrical insulation clearance rather than the whole span ice-shedding scenario. Moreover, the position of maximum jump height along the span of isolated-span transmission lines after ice-shedding could be at around 2/5 of span length, which is different from the conventional opinion that the position is at the midpoint. The results may provide a foundation for the defining of the insulation clearance for an isolated-span transmission line and the structure design of tension tower arms in an iced zone.

Abstract: The realization of practical lithium–sulfur (Li–S) batteries is contingent on the development of innovative electrode design having high-energy, high-power and long-lifespan. Herein, we propose a compact, high-performance, 2D sulfurized-polyacrylonitrile/graphene (2D-SPAN/G)...

Abstract: In this paper, a field study is carried out to monitor the natural frequencies of Malahide viaduct bridge which is located in the north of Dublin. The bridge includes a series of simply supported spans, two of which collapsed in 2009 and were replaced. The replaced spans are stiffer than most of the others and these differences resulted in higher natural frequencies. An indirect bridge monitoring approach is employed in which acceleration responses from an instrumented train are used to estimate the natural frequencies of each span of the viaduct showing the locations of the two replaced spans with higher stiffness. For the indirect approach, an Ensemble Empirical Mode Decomposition (EEMD)-based Hilbert Huang Transform (HHT) technique is employed to identify the natural frequency of each span. This is carried out by analysing the Instantaneous Frequencies (IFs) from the calculated intrinsic mode functions. The average of the IFs calculated using 41 runs of the instrumented train (with varying carriage mass and speed for each run) are used to estimate the natural frequencies. To assess the feasibility of the indirect approach, a bespoke set of direct measurements was taken using accelerometers attached successively on each span of the viaduct. The free and forced vibrations from each span are used to estimate the first natural frequencies. The frequencies obtained from drive-by measurements are compared to those from direct measurements which confirms the effectiveness of indirect approaches. In addition, the instantaneous amplitudes of the drive-by signals are used to indicate the location of the stiffer spans. Finally, the accuracy and robustness of the indirect approaches for monitoring of multi span bridges are discussed.