Identical Spans Research Articles

Span Graph Transformer for Document-Level Named Entity Recognition

Named Entity Recognition (NER), which aims to identify the span and category of entities within text, is a fundamental task in natural language processing. Recent NER approaches have featured pre-trained transformer-based models (e.g., BERT) as a crucial encoding component to achieve state-of-the-art performance. However, due to the length limit for input text, these models typically consider text at the sentence-level and cannot capture the long-range contextual dependency within a document. To address this issue, we propose a novel Span Graph Transformer (SGT) method for document-level NER, which constructs long-range contextual dependencies at both the token and span levels. Specifically, we first retrieve relevant contextual sentences in the document for each target sentence, and jointly encode them by BERT to capture token-level dependencies. Then, our proposed model extracts candidate spans from each sentence and integrates these spans into a document-level span graph, where nested spans within sentences and identical spans across sentences are connected. By leveraging the power of Graph Transformer and well-designed position encoding, our span graph can fully exploit span-level dependencies within the document. Extensive experiments on both resource-rich nested and flat NER datasets, as well as low-resource distantly supervised NER datasets, demonstrate that proposed SGT model achieves better performance than previous state-of-the-art models.

Structural Rehabilitation Work On The Viaduct Over The River Po On The A7 Motorway

The work consisted of the static and seismic retrofitting of the bridge over Po River, on northbound carriageway of highway A7, managed by Milano Serravalle Milano Tangenziali S.p.A. under concession of Italian ministry of transportation. The bridge, designed in the 1960s, is made of reinforced concrete, 800 m long, and consists of 11 identical spans, each with a length of about 69 m. The deck width is 18.4 m, of which 14 m is available for traffic.Over the years, the structure has undergone various strengthening and restoration works, of which the most important took place in 1992, when an integrative slab was built over the existing deck and an external cable pre-stressing system was installed for both the caissons and the buffer beams.The continuous inspections of the structure detected deterioration in various parts of the structure, as well as defects in the realization of the pre-stressing system, which has significantly lost its effectiveness.This article will describe the results of the in-depth investigations carried out on the viaduct, the design of the static and seismic interventions of retrofitting, to restore the structure to a level of complete adequacy to current regulations, and the methods of carrying out the works.

Alternate load path behaviour in structures with non-symmetrical design under column missing scenario

In the design and assessment of reinforced concrete (RC) structure against progressive collapse via single column removal scenario, also known as “alternate load path method”, development of secondary mechanisms, i.e. compressive arch action (CAA) and catenary action (CA) in double-span beams has been investigated and identified in many previous researches. The majority of the experimental tests are conducted on symmetrical double-span beams (identical span length and reinforcement detailing at both beam span). However, variations in details of beams adjacent to one another are not uncommon in RC building designs and constructions. Hence, a research study (as presented in this paper) with total of 5 RC frame tests are conducted to investigate the development of secondary mechanisms (CAA and CA) in a double-span beam with unsymmetrical 1) span length and 2) beam detailing. For each unsymmetrical case (span length and beam detailing), there will be 1 unsymmetrical double-span beam, and 2 symmetrical double-span beams (each representing one side of the unsymmetrical double-span beam) to serve as reference for quantifying the development of secondary mechanism in unsymmetrical double-span beams. The behaviour and development of secondary mechanisms are thoroughly analysed based on test observation, measured forces and displacements, etc.

Virtual Learning and Memory Dissonance

This study aimed to find out declarative memory recalls during online classes. Using a qualitative approach, the instruments used were simple and difficult word-sets. The data were collected through Zoom and WhatsApp platforms and later analyzed using interactive analysis. The results revealed two dissonances encountered: Informational Loss and Built-Up Dissonance. Initially, in the simple-word set, the majority of the students encountered Informational Loss 74 times (after 30 seconds) increasing to 97 times (after 30 minutes). In difficult word sets, it occurred 144 times, increasing to 154 times within identical spans. Regarding Built-Up Dissonance, it occurred 19 times (after 30 seconds), decreasing to 13 times (after 30 minutes) in simple word sets, and 27 times (after 30 seconds), increasing to 30 times (after 30 minutes) in difficult word sets. Surprisingly, it was found that in the recall test, linguistic buffering was generally employed instead of visual buffering. This finding helps teachers understand that virtual learning prompts need to be accompanied by activities involving procedural memory to minimize dissonances.

Experimental investigation on alternate load path mechanisms in double-span beams with unsymmetrical span lengths and reinforcement ratios

In the design and assessment of reinforced concrete (RC) structures against progressive collapse via single column removal scenarios, also known as the “alternate load path (ALP) method”, the development of secondary mechanisms in double-span beams, i.e. compressive arch action (CAA) and catenary action (CA), has been thoroughly investigated and identified in many previous studies. The majority of the experimental tests were conducted on symmetrical double-span beams (identical span length and steel reinforcement ratio for both beams). However, variations in span length and reinforcement details of beams adjacent to one another are common in RC buildings due to architectural requirements. Hence, an experimental study with a total of 6 tests was conducted to investigate the development of ALP mechanisms (CAA and CA) in double-span RC frames with unsymmetrical 1) span length and/or 2) longitudinal reinforcement ratio. The 6 tests included 3 symmetrically-designed specimens that served as the baseline to facilitate comparison and quantification of the ALP development for the other 3 unsymmetrical continuous beams. The behaviour and development of ALP mechanisms in all the 6 specimens were analysed at structural level including general observations and measurements of the external forces, displacements, and strains. Last but not least, a simplified method that was initially developed based on symmetrical test data was employed to validate unsymmetrical test results, with the aim to provide a robust and simple tool for preliminary design considerations of the ALP mechanisms.

Experimental and meso-scale investigation of size effect on fracture properties in three-point concrete beams (TPB)

In this study, the size effect on concrete fracture parameters has been investigated in three distinct groups. While the geometry is similar across each group, the span-to-height ratio varies among the three groups. The study investigates the impact of three different span-to-height ratios (1.85, 2.65, and 4) and five different notch-to-beam height ratios (0.1, 0.2, 0.3, 0.4, and 0.5) by using three-point notched beams (TPB). Beams with identical spans but different heights are used. A new method is proposed to determine the fracture properties of concrete based on the Boundary Effect Method (BEM). A proposed formula for the fictitious cracks is presented based on the results of numerical analyses at the mesoscale and used in the BEM to determine the values of tensile strength and fracture toughness with the effects of span-to-height ratio. The established mesoscale fracture model reproduces the load-displacement curves of 3 PB specimens concrete, which verifies the rationality of the model with the experimental results. Numerical simulation reveals that the fictitious crack length in concrete is highly sensitive to the size of aggregates, their distribution and spacemen’s dimensions. Discussion on BEM based on principles of mathematical fitting and data processing is provided for more objective quasi-brittle fracture experiments and modeling. The size effect law (SEL) is limited by its requirement for sample geometries to be similar, which introduces some additional error when applied to samples with dissimilar geometries. To minimize this error, this study proposes a new formulation within the BEM method. It is found that the fracture parameters predicted by the BEM method using the proposed formulation for different geometries are consistent with the size effect law (SEL) for similar geometries.

Progressive Collapse Analysis of Single-Layer Latticed Domes With Fabricated Joints

Progressive collapse accidents of single-layer latticed domes seriously threaten public safety. The progressive collapse-resisting capacity (PCRC) is gradually becoming an essential requirement in the design of spatial structures. Currently, the joint system used in spatial structures can be divided into two categories: welded joints and fabricated joints. The semi-rigidity of fabricated joints may have a significant influence on the PCRC of single- layer latticed domes. In this study, the PCRCs of single-layer fabricated latticed domes with identical span and rise-to-span ratio are evaluated based on the critical progressive collapse load (CPCL). The collapse mechanism of single-layer latticed domes with different grid forms is revealed by progressive analysis. In addition, the effects of joint rigidity, grid form and type of initial failure are further evaluated. The results indicate that the collapse mechanism of single-layer latticed domes includes the radial propagation type and the circumferential propagation type. The latticed domes with quadrilateral grids have much lower PCRC than those with triangular grids. The CPCLs of weld-jointed latticed domes are 5% to 22% higher than those of the fabricated latticed domes with the same grid form. The above influence should be fully considered in the progressive collapse-resisting design of latticed domes with fabricated joints.

Experimental tests of two span continuous concrete beams reinforced with hybrid GFRP-Steel bars

The current paper aimed at investigating the flexural performance of five large-scale continuous concrete beams reinforced by both steel bars and glass fibre reinforced polymer (GFRP). All the studied specimens had the same geometrical dimensions, with 200 mm width, 300 mm depth, and two identical spans of 2600 mm. The quantity of longitudinal steel reinforcement, GFRP reinforcement, and hybrid reinforcement ratio at the top and bottom layers of beams were the key parameters explored in this study. The experimental findings indicated that using the hybrid reinforcement of steel and GFRP in multi-span continuous concrete beams exhibited a ductile behaviour. However, the hybrid ratio of steel bars/GFRP is critical for restricting the extent of moment redistribution ratios. Moreover, using the same hybrid reinforcement ratios at sagging and hogging regions led to a limited moment redistribution. On the other hand, the hybrid beams strengthened by various hybrid ratios in the critical sections of the tested beams demonstrated a remarkable moment redistribution up to 43 %.The test results were compared with the available theoretical model and equations for predicting the beams’ moment capacity. It was found that the ACI.440.2R-08 reasonably predicted the flexural capacity of tested beams whereas the Yinghao and Yong equation underestimated the flexural capacity in the hogging sections. It was also shown that using the collapse mechanism with plastic hinges at sagging and hogging sections yielded good predictions for the loading capacity of hybrid reinforced concrete continuous beams.

Resonance of railway vehicles induced by floating-slab tracks: mechanism and countermeasures

For a railway vehicle moving over a series of floating-slab (FS) tracks with identical spans at a constant speed, track-induced resonance on the railway vehicle could occur when any of the frequencies of the FS track coincides with any of those implied by the wheel loads. Under this condition, the wheel–rail interaction will be aggravated and the ride comfort of railway vehicles will be deteriorated. This paper presents an experimental and numerical investigation of the mechanism and countermeasures for the resonant response of a metro vehicle induced by eccentric wheels travelling on FS tracks. The characteristics of the resonant response of the metro vehicle are revealed through the field tracking tests. A vehicle–track model considering the FS tracks and eccentric wheels is developed to analyse the resonant mechanism. Several countermeasures, including optimal design of FS track structure and elimination of wheel eccentric wear, are proposed to restrain the resonant vibration. The results show that the resonance caused by the eccentric wheels moving over FS tracks is the root causes for the ride comfort reduction of the metro vehicle. The field tests validate that re-profiling eccentric wheels can significantly eliminate the resonance phenomenon and enhance vehicle dynamics performances.

Improving the Efficiency of I-Beams with a Thin Transverse Corrugated Web Plate

The article describes a way to increase the stability of the transversely corrugated thin web plate of an I-beam due to the use of a double corrugation profile (multi-corrugation). The results of a numerical experiment (performed at LIRA-CAD software) of a large-scale models of beams with transversely corrugated web plates of various profiles (including double corrugation profile), with identical spans, cross sections, boundary conditions, loads, and material characteristics are presented. Distribution diagram of normal and shear stresses in cross sections, deflections, and the forms of buckling of corrugated web plates with safety factors for various models are presented. Based on the calculation results, a comparative analysis of the stress-strain state of the beam models was completed.

Resonance and cancellation phenomena in two-span continuous beams and its application to railway bridges

The objective of this study is to evaluate the vibratory response of two-span continuous beams subjected to moving loads and, in particular, to investigate the maximum resonance and cancellation of resonance phenomena. The main practical interest is the evaluation of the maximum acceleration response in railway bridges, which is one of the most demanding Serviceability Limit States for traffic safety according to current regulations. Two-span continuous bridges, in their simplest version (i.e. uniform identical spans), present antisymmetric and symmetric modes with closely spaced natural frequencies, leading to a more involved dynamic behaviour than that of simply-supported bridges. First, the free vibration response of a Bernoulli-Euler two-span beam after the passage of a single load at constant speed is formulated analytically, and non-dimensional speeds leading to cancellation or maximum response in free vibration are obtained for each mode. Then, these conditions are equated to resonant speeds induced by equidistant load series, and span length-to-characteristic distance ratios causing cancelled out resonances, or remarkably prominent ones, are obtained. Based on the previous derivations, a methodology for detecting which could be the most aggressive trains for a particular structure based on pure geometrical considerations is discussed. Finally, the applicability of the theoretical derivations is shown through the numerical analysis of two real bridges belonging to the Swedish railway network.

SNR Model for Generalized Droop With Constant Output Power Amplifier Systems and Experimental Measurements

Submarine optical transmission systems are commonly operated with constant output power amplifiers. The Gaussian Noise (GN) model of propagation was generally developed in the context of constant gain amplification and accounts for amplified spontaneous emission (ASE) noise and nonlinear interference (NLI) noise. Recently, new models have been proposed and developed to predict signal-to-noise ratio (SNR) models for systems with constant output power amplification that account for the phenomenon known as signal droop, or more broadly, generalized droop (GD). Here we describe a GD model within the context of noises as generated in the GN model, and then further including other distributed noise generation such as might occur for crosstalk in multicore optical fibers. The model results in simple expressions for SNR, signal power, and noise powers as a function of the number of identical spans. We provide numerical modeling confirmation of the analytical model for different formats, and experimental transmission data that is fully consistent with the model.

Kashmir from Barriers of Discomfort to Hope: A Case of Hurriyat Conference

<em>The State of Jammu and Kashmir has witnessed turmoil, political instability, social unrest, and discomfort not only during the independence movement but also after the signing of instrument of accession with the Union of India. It has also suffered a lot from the outcomes of some minor incidents during the contemporary period. There are divided and dynamic opinions that have emerged in the state for these underlying crises. The prime civil servants and most prestigious political leaders of the state attribute this development entirely to the state of retardation, whereas others transmit it to the shortage of the government policy to resolve the political aspirations of entities of this geographical area. It might even be a hot discussion whether or not peace emerges from development. There is no denial in the actual incontrovertible fact that the State of Jammu and Kashmir and its geographical area is blessed and bestowed with substantial human and natural resources. However, at an identical span, it is littered with lots of disturbances and lower development than other states which are economically less productive and insufficient in agricultural production. This study endeavors to explore those factors which have made the state handicapped and dependent teeming with disturbances.</em>

Resonance of high-speed trains moving over a series of simple or continuous beams with non-ballasted tracks

For a train composed of a number of identical cars moving over a bridge at high speeds, train-induced resonance on the bridge may occur when any of the frequencies of the bridge coincides with any of those implied by the wheel loads. On the other hand, for a vehicle moving over a series of bridges with identical spans at constant speeds, bridge-induced resonance on the vehicle may occur when any of the frequencies of the vehicle coincides with any of those of the bridges. The objective of this paper is to provide a complete coverage for the train-induced and bridge-induced resonances on the train-bridge system using both the analytical and finite element approaches. Focus will be placed on the interacting resonant mechanism between the two subsystems of the moving train and the bridge. In addition, a vehicle-bridge interaction (VBI) element considering the rails effect is developed. The numerical examples indicate that the train-induced resonance on the bridges takes place at higher speeds, but the bridge-induced resonance on the train cars at lower speeds. Neglecting the rails effect may underestimate slightly the beam response in the high-speed range, and less slightly the moving vehicle response for all speeds considered.

A theoretical investigation on influences of slab tracks on vertical dynamic responses of railway viaducts

A railway viaduct model consisting of infinite spans of elastically-supported girders carrying a slab track of infinite length is established to investigate the influence of the slabs on the vertical dynamic response of the viaduct, when a moving harmonic point load or a moving sprung wheel is applied. The infinite rail, the discontinuous slabs and girders of identical span lengths are idealized as Euler–Bernoulli beams. The rail fasteners, the cushion layer beneath the slab and the elastic bearings at the girder supports are represented by discretely distributed springs of hysteretic damping. Due to the repetitive nature of the girders, the model can be divided into periodic three-beam units by the span length of the girder, and then solved analytically in the frequency domain using the property of periodic structure. Besides the first natural frequency of the girder with elastic bearings, it is found that the resonance frequency of the slab on the cushion layer has a significant influence on the dynamic response of the track and the girder. Parametric excitations due to the moving wheel periodically passing the discontinuous slabs contribute significantly to the wheel/rail interactions.

The Flipped Classroom Model Improves Undergraduate Test Performance in Human Physiology

The intent of this study was to assess whether a flipped classroom based curriculum affects student performance in a comprehensive human physiology course intended for sophomore level undergraduate students. In year one, students (n = 32) received a traditional lecture based instruction lasting 2 hours and 40 minutes each Saturday for one semester. In year two, a separate group of students (n = 50) were required to watch the previous year's recorded lecture prior to class and then attend class where they received a weekly quiz (worth ~12.5% of their grade; cumulatively) followed by an interactive group‐based question and answer period designed to require integration of the information in the lecture. Students in the traditional lecture did not receive quizzes and there was no interactive or group‐based portion of the class. Identical homework assignments and access to tutoring was provided to both sections. Student performance in both sections was assessed based on performance on identical exams. At time of abstract submission, the students in the flipped section have completed two examinations over an identical span of time as the traditional class covering the first 13 chapters of Dee Unglaub Silverthorn's Human Physiology an Integrated Approach (6th Edition). To date, overall examination averages were higher in the flipped classroom (77 ± 1.7 vs. 83 ± 1.5; P = 0.02). Taken together, these data provide evidence that flipped classroom styles can be equally effective or improve performance in the instruction of physiology at the undergraduate level.

Facilitated sequence counting and assembly by template mutagenesis.

Presently, inferring the long-range structure of the DNA templates is limited by short read lengths. Accurate template counts suffer from distortions occurring during PCR amplification. We explore the utility of introducing random mutations in identical or nearly identical templates to create distinguishable patterns that are inherited during subsequent copying. We simulate the applications of this process under assumptions of error-free sequencing and perfect mapping, using cytosine deamination as a model for mutation. The simulations demonstrate that within readily achievable conditions of nucleotide conversion and sequence coverage, we can accurately count the number of otherwise identical molecules as well as connect variants separated by long spans of identical sequence. We discuss many potential applications, such as transcript profiling, isoform assembly, haplotype phasing, and de novo genome assembly.

Live-load response of in-service bridge constructed with precast, prestressed selfconsolidating concrete girders

Results are reported from two rounds of live-load tests of the first Alabama precast, prestressed concrete bridge constructed with self-consolidating concrete (SCC) girders. One span each of bulb-tee BT-54 girders and BT-72 girders were constructed with SCC. Identical spans were constructed with vibrated concrete girders. Tests were conducted just before opening the bridge to traffic and after one year of service. Measured SCC and vibrated concrete girder deflections are directly compared. After accounting for differences in concrete stiffness, measured SCC and vibrated concrete girder strains are also com- pared. Results indicate no significant difference in the flexural response of SCC and vibrated concrete girders to full service loads. Superposition test re- sults confirm linear-elastic response to service loads after one year of service, and no significant deterio- ration of the service-load performance was detected. Concerns about service-load performance should not restrict the implementation of SCC in the construc- tion of precast, prestressed girders.

System Performance Prediction With the Gaussian Noise Model in 100G PDM-QPSK Coherent Optical Networks

We demonstrate that the transmission BER, OSNR penalty, and system margin can be accurately predicted for multiple fiber types using the back-to-back response together with the Gaussian Noise model of nonlinear penalties. We first experimentally quantify the 1600 km link performance of SMF, MDF, and LAF fiber types in a coherent, WDM PDM-QPSK system at both 28 and 32 GBaud employing all-EDFA amplification and nearly identical span lengths to isolate fiber performance effects. We quantify the BER, OSNR transmission penalty, and link margin versus per-channel launch power in both linear and nonlinear transmission regimes. We demonstrate that the total system performance can be directly and accurately predicted using the fiber parameters α, D, and γ, the number spans and noise figures, and back-to-back performance of the transmitter-receiver pair. We also show that the system margins scale as (α |D|/γ2)1/3 as predicted by the Gaussian Noise model of nonlinear penalties in uncompensated systems.

Direct experimental measurement of SRS-induced spectral tilt in multichannel multispan communication systems

Nonlinear SRS-induced tilt of the spectrum of a multichannel DWDM signal is studied experimentally in standard singlemode fibreoptic communication lines. It is found that at a fixed spectral bandwidth and total power the nonlinear SRS tilt is independent of the number of channels, radiation source type, and the initial tilt (positive or negative). In a multispan line consisting of identical spans the total nonlinear tilt of the spectrum (in dB) is proportional to the number of spans, spectral width and total power.