Improving Seq2Seq Grammatical Error Correction via Decoding Interventions

The sequence-to-sequence (Seq2Seq) approach has recently been widely used in grammatical error correction (GEC) and shows promising performance. However, the Seq2Seq GEC approach still suffers from two issues. First, a Seq2Seq GEC model can only be trained on parallel data, which, in GEC task, is often noisy and limited in quantity. Second, the decoder of a Seq2Seq GEC model lacks an explicit awareness of the correctness of the token being generated. In this paper, we propose a unified decoding intervention framework that employs an external critic to assess the appropriateness of the token to be generated incrementally, and then dynamically influence the choice of the next token. We discover and investigate two types of critics: a pre-trained left-to-right language model critic and an incremental target-side grammatical error detector critic. Through extensive experiments on English and Chinese datasets, our framework consistently outperforms strong baselines and achieves results competitive with state-of-the-art methods.Comment: Accept to Findings of EMNLP 202

How Well Do Large Language Models Understand Syntax? An Evaluation by Asking Natural Language Questions

While recent advancements in large language models (LLMs) bring us closer to achieving artificial general intelligence, the question persists: Do LLMs truly understand language, or do they merely mimic comprehension through pattern recognition? This study seeks to explore this question through the lens of syntax, a crucial component of sentence comprehension. Adopting a natural language question-answering (Q&A) scheme, we craft questions targeting nine syntactic knowledge points that are most closely related to sentence comprehension. Experiments conducted on 24 LLMs suggest that most have a limited grasp of syntactic knowledge, exhibiting notable discrepancies across different syntactic knowledge points. In particular, questions involving prepositional phrase attachment pose the greatest challenge, whereas those concerning adjectival modifier and indirect object are relatively easier for LLMs to handle. Furthermore, a case study on the training dynamics of the LLMs reveals that the majority of syntactic knowledge is learned during the initial stages of training, hinting that simply increasing the number of training tokens may not be the `silver bullet' for improving the comprehension ability of LLMs.Comment: 20 pages, 6 figure

Stress Analysis of CFG Pile Composite Foundation in Consolidating Saturated Mine Tailings Dam

Cement fly-ash gravel (CFG) pile is a widely used ground reinforcement technique. This paper aims to address the mechanical characteristics of CFG composite foundation in consolidating saturated mine tailings (MTs) dam. The field static load tests were employed to explore the bearing capacity of the CFG composite foundation, and finite element (FE) models in three dimensions validated through comparison with experimental results were used to discuss the pile-soil stress distribution and pile-soil stress ratio of the CFG composite foundation. The results indicate that the distribution of earth pressure and pile stress is relatively homogeneous and stable over depth and load, while the development of CFG composite foundation bearing capacity is insufficient, in which the developed bearing capacity of CFG piles is less than 50% of its characteristic value. Additionally, compared with the laboratory model test results, the pile-soil stress ratio decreases with the increasing of the load in FEM results proved to better conform to the actual engineering conditions. Furthermore, the deformation modulus and thickness of cushion exert significant influence on pile-soil stress ratio and integral bearing capacity of CFG composite foundation

Experimental and numerical studies on progressive debonding of grouted rock bolts

Understanding the mechanism of progressive debonding of bolts is of great significance for underground safety. In this paper, both laboratory experiment and numerical simulation of the pull-out tests were performed. The experimental pull-out test specimens were prepared using cement mortar material, and a relationship between the pull-out strength of the bolt and the uniaxial compressive strength (UCS) of cement mortar material specimen was established. The locations of crack developed in the pull-out process were identified using the acoustic emission (AE) technique. The pull-out test was reproduced using 2D Particle Flow Code (PFC2D) with calibrated parameters. The experimental results show that the axial displacement of the cement mortar material at the peak load during the test was approximately 5 mm for cement-based grout of all strength. In contrast, the peak load of the bolt increased with the UCS of the confining medium. Under peak load, cracks propagated to less than one half of the anchorage length, indicating a lag between crack propagation and axial bolt load transmission. The simulation results show that the dilatation between the bolt and the rock induced cracks and extended the force field along the anchorage direction; and, it was identified as the major contributing factor for the pull-out failure of rock bolt

New non-destructive method for testing the strength of cement mortar material based on vibration frequency of steel bar: Theory and experiment

Timely and accurately obtaining the strength of pouring material, e.g., concrete, cement mortar, is of great significance for engineering construction. In this paper, a non-destructive, economical and accurate strength detection method that suites for on-site using is proposed for the steel bar cement mortar material. The method based on the relationship between the vibration frequency of the steel bar and the properties of the mortar material, which is obtained by solving the Euler-Bernoulli beam problem. Both Particle Flow Code (PFC) software simulation (calibrated) and Split Hopkinson pressure Bar experiment on test samples of cement mortar and steel bar were performed to verify the theoretically obtained relationship. Studies on samples of various aggregate ratio further confirmed such correspondence. Results show that the dynamic stiffness of the cement mortar material dominates the calculation of the vibration frequency of steel bar, while the combined effect of the density, length, elastic modulus, inertia moment of the steel bar can be safely ignored. A single-valued mapping relation exists in between the dynamic stiffness coefficient and the Uniaxial Compressive Strength (UCS) of the cement mortar sample, i.e., increased dynamic stiffness coefficient with increasing UCS. Both experimental and predicted results showed a linear relationship between the vibration frequency of the steel bar and the strength of the mortar material. Fitted linear relations were proposed with coefficients depending on sample size and aggregate ratio and might serve as a good indicator for the strength of the mortar material. Further studies on the effect of internal defects of the mortar materials as well as on samples of more size and aggregate ratio are required to make the proposed method a practical too

Zmienność ciśnienia górotworu i obciążenia osiowe działające na segmenty obudowy w rejonie przodka spowodowane obecnością uskoków

The cohesion and internal friction angle were characterized as quadratic functions of strain and were assumed to follow the Mohr-Coulomb criterion after the yield of peak strength. These mechanical parameters and their variations in post-peak softening stage can be exactly ascertained through the si-multaneous solution based on the data points of stress-strain curves of triaxial compression tests. Taking the influence of the fault into account, the variation of strata pressure and roadway convergence with coal advancement, the temporal and spatial distribution of axial bolt load were numerically simulated by FLAC3D (Fast Lagrangian Analysis of Continua) using the ascertained post-peak mechanical parameters according to the cohesion weakening and friction strengthening model. The change mechanism of axial load of single rock bolt as abutment pressure changes was analyzed, through the comparison analysis with the results of axial bolt load by field measurements at a coal mine face. The research results show that the simulated results such as the period of main roof weighting, temporal and spatial distribution of axial bolt load are in accordance with field measurement results, so the validity of the numerical model is testified. In front of the working face, the front abutment pressure increases first and then decreases, finally tends to be stable. A corresponding correlation exists between the variation of axial bolt load and rock deformation along the bolt body. When encountered by a fault, the maximum abutment pressure, the influential range of mining disturbance and the roadway convergence between roof and floor before the working face are all increased. In the roadways along the gob, axial bolt loads on the side of the working face decrease, while the other side one increases after the collapse of the roof. As superficial surrounding rock mass is damaged, the anchoring force of rock bolts will transfer to inner rock mass for balancing the tensile load of the bolts.Zwięzłość skał oraz kąt tarcia wewnętrznego zdefiniowano jako kwadratowe funkcje naprężenia, następnie przyjęto że ich rozkład po osiągnięciu naprężenia granicznego opisany jest wzorem Mohra-Coulomba. Wymienione parametry mechaniczne i ich zmienność po osiągnięciu naprężenia granicznego obliczyć można dokładnie poprzez jednoczesne rozwiązanie oparte o analizę punktów na krzywej wykresu rozciągania uzyskanych w testach ściskania trójosiowego. Uwzględniając wpływ obecności uskoku, zmienność ciśnienia w górotworze i konwergencji chodnika wraz z postępem przodka, rozkłady naprę-żeń i obciążeń działających na segmenty obudowy i ich zmienność w czasie i przestrzeni modelowano w oparciu o pakiet FLAC3D (Fast Lagrangian Analysis of Continua), wykorzystując uprzednio obliczone wielkości parametrów mechanicznych dla stanu po osiągnięciu naprężenia granicznego, zgodnie z mo-delem słabnącej zwięzłości i wzmocnionego tarcia. Mechanizm zmiany naprężeń osiowych działających na pojedynczy segment obudowy analizowano w odniesieniu do ciśnienia warstw sąsiadujących, poprzez analizę porównawczą wyników pomiarów obciążeń segmentów obudowy w rejonie przodka. Wykazano, że wyniki symulacji: okresy obciążenia stropu, rozkłady naprężeń i obciążeń działających na elementy obudowy i ich zmienność w czasie i przestrzeni zgodne są z wynikami pomiarów w miejscu, w ten sposób potwierdzając wiarygodność modelu numerycznego. W rejonie przodka ciśnienie warstw sąsiadujących w górotworze najpierw rośnie, następnie maleje, a w końcu stabilizuje się. Istnieje odpowiednia korelacja pomiędzy zmiennością rozkładu naprężeń i obciążeń działających na elementy obudowy a odkształceniem warstw skalnym wzdłuż konstrukcji obudowy. W przypadku wystąpienia uskoku, występuje maksymalne ciśnienie warstw otaczających- poważny czynnik powodujący wszelkiego rodzaju zaburzenia a także nasilenie konwergencji chodnika pomiędzy stropem a podłożem w rejonie przed przodkiem. W chodnikach wzdłuż zrobów, obciążenia osiowe obudowy działające z jednej strony maleją, po drugiej zaś stronie rejonu przodkowego rosną po zawale stropu. Płytka warstwa otaczającego górotworu ulega zniszczeniu, siła podtrzymująca obudowę przeniesiona zostanie wewnątrz górotworu, tak by zrównoważyć naprężenia rozciągające działające na obudowę

Non-destructive testing and pre-warning analysis on the quality of bolt support in deep roadways of mining districts

The bolt support quality of coal roadways is one of the important factors for the efficiency and security of coal production. By means of a self-developed technique and equipment of random non-destructive testing, non-destructive detection and pre-warning analysis on the quality of bolt support in deep roadways of mining districts were performed in a number of mining areas. The measured data were obtained in the detection instances of abnormal in-situ stress and support invalidation etc. The corresponding relation between axial bolt load variation and roadway surrounding rock deformation and stability was summarized in different mining service stages. Pre-warning technology of roadway surrounding rock stability is proposed based on the detection of axial bolt load. Meanwhile, pre-warning indicators of axial bolt load in different mining service stages are offered and some successful pre-warning cases are also illustrated. The research results show that the change rules of axial bolt load in different mining service stages are quite similar in different mining areas. The change of axial bolt load is in accord with the adjustment of surrounding rock stress, which can consequently reflect the deformation and stability state of roadway surrounding rock. Through the detection of axial bolt load in different sections of roadways, the status of real-time bolt support quality can be reflected; meanwhile, the rationality of bolt support design can be evaluated which provides reference for bolting parameters optimization. Keywords: Deep roadways, Bolt support quality, Random nondestructive testing, Surrounding rock stability, Prediction and pre-warnin

applicationoffuzzyoptimalselectionofsimilarslopestotheevaluationofslopestability

The numerical calculation method is widely used in the evaluation of slope stability, but it cannot take the randomness and fuzziness into account that exist in rock and soil engineering objectively. The fuzzy optimization theory is thus introduced to the evaluation of slope stability by this paper and a method of fuzzy optimal selection of similar slopes is put forward to analyze slope stability. By comparing the relative membership degrees that the evaluated object sample of slope is similar to the source samples of which the stabilities are detected clearly, the source sample with the maximal relative membership degree will be chosen as the best similar one to the object sample, and the stability of the object sample can be evaluated by that of the best similar source sample. In the process many uncertain influential factors are considered and characteristics and knowledge of the source samples are obtained. The practical calculation indicates that it can achieve good results to evaluate slope stability by using this method

Mechanical behavior of sandstone during post-peak cyclic loading and unloading under hydromechanical coupling

This paper investigates mechanical behaviours of sandstone during post-peak cyclic loading and unloading subjected to hydromechanical coupling effect, confirming the peak and residual strengths reduction laws of sandstone with water pressure, and revealing the influence of water pressure on the upper limit stress and deformation characteristics of sandstone during post-peak cyclic loading and unloading. Regarding the rock strength, the experimental study confirms that the peak strength σp and residual strength σr decrease as water pressure P increases. Especially, the normalized strength parameters σp/σpk and σr/σre was negatively and linearly correlated with the P/σ3. Moreover, the Hoek-Brown strength criterion can be applied to describe the relationship between effective peak strength and effective confining stress. During post-peak cyclic loading and unloading, both the upper limit stress σp(i) and crack damage threshold stress σcd(i) of each cycle tend to decrease with the increasing cycle number. A hysteresis loop exists among the loading and unloading stress–strain curves, indicating the unloading deformation modulus Eunload is larger than the loading deformation modulus Eload. Based on experimental results, a post-peak strength prediction model related to water pressure and plastic shear strain is established