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We propose a dynamic combined-mode traffic network model considering transfer behaviors. We assume that travelers can be classified into two classes: one class is pure-mode travelers who complete a trip by single transportation mode, and another is combined-mode travelers who cover a journey by car, bus, and so forth. The multimode point queue model is used to model the interaction of cars and buses on the network. We present an integrated variational inequality formulation to capture the complex traveler choice behaviors such as departure time choices, transfer point, and route choices. Finally, a numerical example is given to illustrate the effectiveness of the proposed heuristic algorithm and model., Author(s): ShuGuang Li (corresponding author) [1]; QingHua Zhou [2] 1. Introduction Over the past decades, many researchers have been devoted to static multimodal network models and algorithms. Recently, Bliemer [1] [...]

An increasing number of extra-long highway tunnels have been built and put into operation around the world, but the quantified segmentation criteria for evaluating the in-tunnel operational status have not yet been enacted up till the present moment. Meanwhile, ventilation facilities could not satisfy the dynamic requirements of fresh air demand under fast spatial-temporal variation of traffic conditions and operating environment. In this study, the operational data collected from an extra- long highway tunnel were deeply analyzed using big data technology. By combining traffic flow and environmental monitoring data, a data-driven perception model based on the Random Forests was structured. The prediction results show that the proposed model provides better performances as compared to contrast models, indicating it had better ability to adapt to the dynamic changes of in-tunnel operational status while realizing accurate prediction. The designed intelligent control strategies of ventilation facilities and traffic operation applying for different operational status would provide a theoretical basis and data support for lifting the level of intelligent control as well as promoting energy saving and consumption reducing in extra-long highway tunnels., 1. Introduction By the end of 2016, 815 extra-long highway tunnels with a total length of 3622.7 km were built in China [1]. Owing to the influence of traffic volume [...]

Applying big data technology, this study presents a customer segmentation method of Electronic Toll Collection (ETC) based on vehicle behavioral characteristics. A segmentation index system of ETC customers comprising Recency, Frequency, and Monetary is extracted and constructed using ETC data. The whole-sample clustering analysis of ETC customers is accomplished with the Clustering LARge Applications (CLARA) algorithm while overcoming the invalidation problem of big data clustering. A decision tree on ETC customer segmentation is constructed and transformed into a set of segmentation rules. Empirical results indicate that the proposed method is better able to analyze travel characteristics and to present values and appreciation potentials for ETC customer classification. This method provides an innovative idea for implementing precision marketing and establishing hierarchical discount rates for ETC customers. Furthermore, it provides theoretical support to increase the ETC customer scale and payment ratio, thus improving the decision-making level in expressway operation and management., 1. Introduction Electronic Toll Collection (ETC) is an essential part of the Intelligent Transportation System (ITS). ETC not only reduces travel time and energy consumption but also saves infrastructure and [...]

Lung adenocarcinoma is the most common non-small-cell lung cancer. In this paper, we aim to investigate the expression of chemokine ligand 1 (cx3cl1) and chemokine ligand 28 (CCL28) in spinal metastases of lung adenocarcinoma and their correlation with clinical features and prognosis. We analyzed the clinical data of 40 patients with lung adenocarcinoma and spinal metastases who underwent surgery in our hospital from January 2018 to January 2021 retrospectively. The expression levels of cx3cl1 and CCL28 in bone metastases were detected by immunohistochemistry, and the staining results were sorted and classified. Combined with the follow-up results and clinicopathological data, we statistically analyzed the expression of cx3cl1 and CCL28 in spinal bone metastases and their correlation with prognosis. Among the 40 patients with spinal metastasis of lung adenocarcinoma, 7 cases were strongly positive for cx3cl1, 25 cases were moderately positive, and 8 cases were weakly positive and negative. CCL28 was strongly positive in 9 cases, moderately positive in 26 cases, weakly positive and negative in 5 cases. The expression of cx3cl1 was correlated with ECOG score (P = 0.005) and visceral organ metastasis (P = 0.004), but not with age, sex, and the number of bone metastases (P > 0.05). The expression of CCL28 was correlated with ECOG score (P = 0.022) and visceral organ metastasis (P = 0.003), but not with age, sex, and the number of bone metastases (P > 0.05). The OS of patients with strong cx3cl1 positive was significantly shorter than that of patients with medium positive and weak positive (P < 0.001). The survival time was 10, 7, and 4 months, respectively. The OS of patients with strong positive CCL28 was significantly shorter than that of patients with medium positive and weak positive CCL28 (P = 0.004). The survival time was 12, 8, and 4 months, respectively. Univariate analysis showed that ECOG score (P < 0.001), chemotherapy (P = 0.032), visceral organ metastasis (P = 0.002), cx3cl1 expression (P < 0.001), and CCL28 expression (P = 0.004) were the risk factors of OS. Cox regression analysis showed that the expression of cx3cl1 was an independent risk factor for OS in patients with spinal metastasis of lung adenocarcinoma (P = 0.044). Cx3cl1 and CCL28 were highly/strongly positive in spinal metastases of lung adenocarcinoma. The level of cx3cl1 can be used as an index to judge the clinical prognosis of patients with spinal metastasis of lung adenocarcinoma, which can better reflect the prognosis of patients than CCL28. [ABSTRACT FROM AUTHOR]

A method of rapidly demarcating the critical commutation failure (CF) region of a multi-infeed high-voltage direct-current (HVDC) system is proposed. Based on the nodal impedance matrix and nodal voltage interaction factor, for different AC fault conditions—both balanced and unbalanced—a method of calculating the extinction angles of converters in multi-infeed HVDC systems is deduced in detail. First, the extinction angles of convertor stations under single-phase, double-phase, and three-phase ground faults and line-to-line faults occurring at any bus in an AC system are calculated. The minimum extinction angle serves as a CF criterion. If the calculated extinction angle for a certain bus is smaller than the minimum extinction angle, then a fault at that bus will cause CF of the HVDC system and put that bus into a failed bus set. The critical failure impedance boundaries of the topology diagram can therefore be demarcated by examining every bus in the AC system. The validity and accuracy of the proposed index and the method were verified by calculation results based on the three-infeed HVDC system model of the IEEE 39-bus system. Finally, the critical failure impedance boundary was demarcated in the IEEE 118-bus system to demonstrate the application in a wider range of systems. [ABSTRACT FROM AUTHOR]

Aiming at the cyclic impact deformation and failure of tunnel surrounding rock under shear stress, a self-developed rotation-impact simulation test platform was used to determine the number of failures, stress-strain curves, and energy in the process of cyclic impact failure. The failure process of rock under different impact velocities and shear stresses has been systematically studied. Results show that, under the same impact speed, the shear stress will increase with the increase in the rotation speed, but an upper limit will exist. When the rotation speed reaches this upper limit, the shear stress will no longer increase. The presence of shear stress will reduce the number of impacts required for rock failure. When the impact speed is 7.2 m/s, the number of impacts at the maximum rotation speed is 60% of the static state. When the impact velocity is 16.8 m/s, this value is only 33.3%. At the same impact velocity, the stress-strain curves under different rotation speeds do not change significantly, but with the increase in the rotation speed, the slope of the elastic stage of the stress-strain curve gradually decreases, and the corresponding stress of the rock sample decreases when the maximum strain is reached. With the increase in shear stress, the crushing specific energy required for rock failure gradually decreases. The greater the impact velocity, the more obvious the impact of shear stress on energy dissipation. In the tunnel process, when the surrounding rock is subjected to impact loads from different directions, only the axial strain analysis will have certain safety hazards, and timely support and reinforcement work are required. [ABSTRACT FROM AUTHOR]

In geotechnical engineering and geological survey, the stratum structure and its corresponding physical and mechanical properties are the most concerned. The stratum structure not only affects the safety of the project but also plays a decisive role in the construction method and construction sequence. In this paper, a new type of stratum geological interface recognition system is adopted, and an R-20 rotary drilling rig is used to conduct on-site drilling experiments for a granite site with no ventilation. The research results show that the system can monitor and record the main parameters (axial pressure, drilling rate, rotation speed, flushing fluid pressure, and torque) of the drilling rig during the drilling process. The comparative analysis of monitoring data and on-site survey results shows that different drilling parameters have different sensitivities to changes in the formation structure. According to the prediction accuracy, the ranking from high to low is drilling rate, axial pressure, torque, rotation speed, and flushing fluid pressure. In drilling engineering, by observing the change law of drilling rig parameters, not only can the position of the special rock mass interlayer be predicted, but also the stratum structure and strength can be identified, and the prediction formula is also given. Based on the established drilling specific energy formula, the energy analysis method is used to predict the formation structure and compressive strength, and the corresponding prediction formula is given. The research results show that, compared with the single drilling parameter prediction method, the rock-soil structure and strength identification method based on energy theory has higher prediction accuracy and can meet engineering needs. [ABSTRACT FROM AUTHOR]

Due to its unique technological characteristics, coal mining and production often encounter an acid corrosion environment caused by acid gases. Acid erosion and a series of chemical reactions caused by it often led to the deterioration of coal, rock, support structure, etc. and induced serious safety accidents. To further explore the macro-mesoscopic damage evolution law and failure mechanisms of rock masses under corrosion conditions through numerical simulation, a zonal refined numerical model that can reflect the acid corrosion characteristics of sandstone is established based on CT and digital image processing (DIP). The uniaxial compression test of corroded sandstone is simulated by ABAQUS software. Comparing the numerical simulation results with the physical experiment results, we found that the three-dimensional finite element model based on CT scanning technology can genuinely reflect sandstone's corrosion characteristic. The numerical simulation results of the stress-strain curve and macroscopic failure mode of the acid-corroded sandstone are in good agreement with the experimental results, which provides a useful method for further studying the damage evolution mechanism of the acid-corroded rock mass. Furthermore, the deformation and damage evolution law of the corroded sandstone under uniaxial compression is qualitatively analyzed based on the numerical simulation. The results show that the rock sample's axial displacement decreases gradually from top to bottom under the axial load, and the vertical variation is relatively uniform. In contrast, the rock sample's removal gradually increases with the increase of axial pressure, and the growth presents a certain degree of nonuniformity in the vertical. The acid-etched rock sample's damage starts from both the end and the middle; it first appears in the corroded area. Moreover, with the displacement load increase, it gradually develops and is merged in the middle of the rock sample and forms macroscopic damage. [ABSTRACT FROM AUTHOR]

Desert sand is one of the current research hotspots in alternative materials for concrete aggregates. In the process of practical application, compressive strength is an essential prerequisite for studying other properties. Based on the current research situation, a prediction technology of compressive strength of desert sand concrete (DSC) is proposed based on an artificial neural network (ANN) and a particle swarm optimization (PSO). The technology is a prediction model that adjusts the network architecture by using the PSO method based on the ANN optimization model. Water-binder ratio, sand ratio, replacement rate of desert sand, desert sand type, fly ash content, silica fume content, air content, and slump were selected as the neural network's inputs. The compressive strength data of 118 different combinations of influencing variables were tested to establish the dataset. The results show that the PSO method is efficient for the ANN in DSC compressive strength research. Furthermore, referring to this method, DSC is applied to the shotcrete of tunnels in construction engineering successfully, and the dust particle content during construction is evaluated. [ABSTRACT FROM AUTHOR]

The paper aims to solve the problem that the primary support of the deep-buried large-section loess tunnel of the Haolebaoji-Ji'an Railway was damaged due to excessive force. Based on indoor tests, on-site construction feedback, and monitoring measurement data, the surrounding rock deformation and structural forces with different support schemes were compared and analyzed. The engineering application methods and mechanism of the support resistant limiting damper (SRLD) technology were studied. The results show that for the deep-buried large-section loess tunnels, under the premise of ensuring the self-supporting capacity of the surrounding rock is not significantly reduced, and the loose pressure is not significantly increased, the resistance-limiting and high-ductility support concept that can control the deformation and the energy release of the surrounding rock is reasonable and feasible. The support resistant limiting damper (SRLD) is a reasonable and practical resistance-limiting and high-ductility support method, which successfully solved the failure of the primary support of the deep-buried large-section loess tunnel. The SRLD's integrity and safety are guaranteed, the materials are easy to obtain, the processing is convenient, and the construction is simple and easy to operate. The SRLD is a safe and economic support structure. [ABSTRACT FROM AUTHOR]

The physicomechanical deterioration characteristics of sandstone subjected to H2SO4, HCl, and H2O solutions of different pH values are studied by the method of long-term accelerated immersion. The quantitative relationships between the damage variables based on CT (computer tomographic identification technology) numbers and the immersion time, the uniaxial compressive strength, the peak point strain, and the elastic modulus of rock samples are analyzed. The test results indicate that the pH value of immersion solutions, the dissolution rate of Ca2+ and Na+, and the quality change of rock samples show visible stage characteristics under acidic environment. With the soaking time extended, the pH value of solutions increases gradually, and the quality change of rock samples decreases gradually. The smaller the pH value of immersion solutions is, the higher the dissolution rate of Ca2+ and Na+ is. However, the cation dissolution rate under a weak acid environment with a high pH value has little difference with that under the distilled water (pH = 7). With the increase of the soaking time and the acidity, the compaction stage of rock samples becomes longer, the elastic stage becomes shorter, the deterioration degree of mechanical parameters becomes more extensive, and the destruction of sandstone samples shows ductility characteristics increasingly. The corrosion degree of corroded sandstone samples is quantitatively represented by microscopic damage variables based on CT numbers. The regression analysis results show that damage variables of acid-corroded sandstone samples have a power function relationship with soaking time and an exponential function relationship with peak strength, peak point strain, and elastic modulus. [ABSTRACT FROM AUTHOR]

This paper takes the Dizong tunnel engineering as its background. Combined with the on-site monitoring data, the wavelet packet program based on MATLAB was compiled to study the vibration response of the four-story masonry building in a typical southwestern mountainous area of China under the blasting load. The results showed that the maximum particle velocity increased to the 3rd floor and attenuation occurred on the 4th floor. The particle velocity in the z-direction was the largest and should be paid attention. The dominant frequency of the building showed a trend from high frequency to low frequency, the duration became short, and the acceleration decreased to the 4th floor. With the increase of the building floor, the main frequency domain of the building decreased and then gradually tended to the low-frequency domain. The high-frequency particle velocity gradually decreased, gathered to the low frequency, and developed from the dispersed multiband to the concentrated low-frequency band. The total energy value of vibration increased to the 3rd floor and then decreased to the 4th floor. The energy of the building was between 0 and 171.6 Hz. The higher the floor was, the more concentrated the energy was in the low-frequency domain. [ABSTRACT FROM AUTHOR]

The 28 days cured cement mortar samples were soaked in HCl (pH = 1 and 2) and H2O (pH = 7) solutions for 90 days. By monitoring the ion concentration of H+ and Ca2+ and measuring the changes in weight loss, longitudinal wave velocity, and uniaxial compressive strength values of the corroded mortar, the physicochemical and mechanical properties of the mortar specimens were studied. Experimental results indicate that the process of the mortar sample subjected to HCL erosion has apparent stage characteristics. In the initial stage of corrosion, the chemical reaction increased the porosity of the specimen, which leads to the decrease of longitudinal wave velocity of the samples. At the same time, the corrosion solution continuously penetrates into the mortar pore system, which leads to the increase of the mass, and it is considered that the diffusion process plays a leading role during this period. Moreover, the colloidal compounds generated by the chemical reaction can not only fill the pore space but also block the continuous reaction, which led to the increase of the longitudinal wave velocity of the specimen. With the prolonging of corrosion time and infiltration path, the pH value and the concentration of Ca2+ tend to be stable, the diffusion action is weakened, and the chemical reaction is continuous, which led to the decrease of the mass and wave velocity gradually. It is considered that the chemical reaction plays a leading role in this process. Based on the induction and analysis of the test results, a generalized porosity model regarding the increase of the porosity and the decrease of effective bearing area of the mortar sample was proposed. The relation between the uniaxial compressive strength and the corrosion time of the corroded mortar is deduced, and the unknown parameters are determined based on the regression analysis of the test data. [ABSTRACT FROM AUTHOR]

The influence of acid solution and immersion time on the physicomechanical properties of sandstone is investigated. Uniaxial compression tests on sandstone samples are conducted to determine the variations of relative mass, deformation, and strength characteristics of sandstone subjected to different pH sulfuric acid corrosion values. The changes of pH and Mg2+ and Ca2+ concentration of immersion solutions are monitored during soaking. The corrosion mechanism of sandstone attacked by the acid solution is discussed with the results of SEM tests. Based on the nondestructive CT scanning test, the damage variables of acid-corroded sandstone are deduced, and the damage degree of sandstone is quantitatively analyzed. The results indicate that the deformation characteristics of sandstone samples under acid attack are characterized by the softening of rock, and the softening degree gradually increases with the increase of the acidity and the soaking time. The peak strength of sandstone samples declines as soaking time extends. The chemical effects lead to a large amount of dissolution of the rock mineral assemblage, resulting in the large-scale development of the pores inside the rock, which changes the macroscopic mechanical properties. The damage variables of acid corrosion sandstone based on CT numbers are deduced, and the quantitative relationship between damage variables and immersion time is established, which provides a basis for constructing a damage constitutive model of sandstone in the acidic environment. [ABSTRACT FROM AUTHOR]

The problem of scheduling jobs with delivery times on parallel machines is studied, where each job can only be processed on a specific subset of the machines called its processing set. Two distinct processing sets are either nested or disjoint; that is, they do not partially overlap. All jobs are available for processing at time 0. The goal is to minimize the time by which all jobs are delivered, which is equivalent to minimizing the maximum lateness from the optimization viewpoint. A list scheduling approach is analyzed and its approximation ratio of 2 is established. In addition, a polynomial time approximation scheme is derived. [ABSTRACT FROM AUTHOR]