A Feature Extraction Method Based on Feature Fusion and its Application in the Text-Driven Failure Diagnosis Field

As a basic task in NLP (Natural Language Processing), feature extraction directly determines the quality of text clustering and text classification. However, the commonly used TF-IDF (Term Frequency & Inverse Document Frequency) and LDA (Latent Dirichlet Allocation) text feature extraction methods have shortcomings in not considering the text’s context and blindness to the topic of the corpus. This study builds a feature extraction algorithm and application scenarios in the field of failure diagnosis. A text-driven failure diagnosis model is designed to classify and automatically judge which failure mode the failure described in the text belongs to once a failure-description text is entered. To verify the effectiveness of the proposed feature extraction algorithm and failure diagnosis model, a long-term accumulated failure description text of an aircraft maintenance and support system was used as a subject to conduct an empirical study. The final experimental results also show that the proposed feature extraction method can effectively improve the effect of clustering, and the proposed failure diagnosis model achieves high accuracies and low false alarm rates

A two-dimensional hybrid with molybdenum disulfide nanocrystals strongly coupled on nitrogen-enriched graphene via mild temperature pyrolysis for high performance lithium storage

A novel 2D hybrid with MoS₂ nanocrystals strongly coupled on nitrogen-enriched graphene (MoS₂/NGg-C₃N₄) is realized by mild temperature pyrolysis (550 °C) of a self-assembled precursor (MoS₃/g-C₃N₄–H⁺/GO). With rich active sites, the boosted electronic conductivity and the coupled structure, MoS₂/NGg₋C₃N₄ achieves superior lithium storage performance

Effect of Grain Coalescence on Dislocation and Stress Evolution of GaN Films Grown on Nanoscale Patterned Sapphire Substrates

Two types of nucleation layers (NLs), including in-situ low-temperature grown GaN (LT-GaN) and ex-situ sputtered physical vapor deposition AlN (PVD-AlN), are applied on cone-shaped nanoscale patterned sapphire substrate (NPSS). The initial growth process of GaN on these two NLs is comparably investigated by a series of growth interruptions. The coalescence process of GaN grains is modulated by adjusting the three-dimensional (3D) temperatures. The results indicate that higher 3D temperatures reduce the edge dislocation density while increasing the residual compressive stress in GaN films. Compared to the LT-GaN NLs, the PVD-AlN NLs effectively resist Ostwald ripening and facilitate the uniform growth of GaN grains on NPSS. Furthermore, GaN films grown on NPSS with PVD-AlN NLs exhibit a reduction of over 50% in both screw and edge dislocation densities compared to those grown on LT-GaN NLs. Additionally, PVD-AlN NLs result in an increase of about 0.5 GPa in the residual compressive stress observed in GaN films

Design and Implementation of Freeway Infrastructure Safety and Emergency Management System

AbstractAs an important content of freeway safety management, the freeway infrastructure safety and emergency management system can bring great social effect. In this article, a comprehensive freeway infrastructure safety and emergency management system was built by following steps: firstly, research significance, research status and the paper framework were illustrated. Secondly, in allusion to five kinds of transportation infrastructure: pavement, bridge, tunnel, side slope and ancillary facility, the existing infrastructure testing indexes were summarized, and the relations between traffic safety and these testing indexes were quantified. Thirdly, according to the different characteristic of five kinds of infrastructures, comprehensive safety evaluation models were proposed in order to evaluate the safety of freeway infrastructure. Fourthly, the system of emergency management and emergency plans were expounded. Finally, the system software was developed on the base of research about system framework, database system and Web GIS technology. This system has strong practicability, which can compensate for the deficiencies of the infrastructure detection in the past and provide a new informationalized management platform for freeway management

Satisfaction of Logistics Dispatchers Who Use Electric Tricycles\linebreak for the Last Mile of Delivery: Perspective from Policy Intervention

This paper investigates the satisfaction factors of logistics dispatchers who used electric tricycles for the last mile of delivery under policy intervention, and a questionnaire survey is conducted on the last-mile dispatchers in Nanjing. Based on four principal components extracted by exploratory factor analysis, the structural equation model (SEM) for the relationship between exogenous variables (sound policy, legality, and standardizing system) and endogenous variables (perceived convenience and satisfaction) is established to obtain the factors influencing the satisfaction of dispatchers. The results indicate that the correlation coefficients between the perceived convenience, sound policy, legality, standardizing system and the dispatchers’ satisfaction are 0.606, 0.448, 0.242 and −0.366, respectively. The correlations between perceived convenience, sound policy, legality and dispatchers’ satisfaction are significantly positive. The correlations between standardizing system and dispatchers’ satisfaction are negative. Finally, corresponding improvement policies are proposed based on the analysis of the model. The research results help improve the dispatcher’s satisfaction during the last-mile distribution process and provide support for standards by using electric tricycles and the formulation of new policies

The Uncapacitatied Dynamic Single-Level Lot-Sizing Problem under a Time-Varying Environment and an Exact Solution Approach

The dynamic lot-sizing problem under a time-varying environment considers new features of the production system where factors such as production setup cost, unit inventory-holding cost, and unit price of manufacturing resources may vary in different periods over the whole planning horizon. Traditional lot-sizing theorems and algorithms are no longer fit for these situations as they had assumed constant environments. In our study, we investigated the dynamic lot-sizing problem with deteriorating production setup cost, a typical time-varying environment where the production setup is assumed to consume more preparing time and manufacturing resources as the production interval lasts longer. We proposed new lot-sizing models based on the traditional lot-sizing model considering the changing setup cost as a new constraint, called uncapacitatied dynamic single-level lot-sizing under a time-varying environment (UDSLLS-TVE for short). The UDSLLS-TVE problem has a more realistic significance and higher research value as it is closer to reality and has higher computational complexity as well. We proposed two mathematical programming models to describe UDSLLS_TVE with or without nonlinear components, respectively. Properties of the UDSLLS-TVE models were extensively analyzed and an exact algorithm based on forward dynamic programming (FDP) was proposed to solve this problem with a complexity of O (n2). Comparative experiments with the commercial MIP solver CPLEX on synthesized problem instances showed that the FDP algorithm is a global optimization algorithm and has a high computational efficiency

Study and application of a new blockage remover in polymer injection wells

With the extensive application of polymer flooding technology in offshore oilfields, the plugging in polymer injection wells has become more and more severe, which seriously affects the oil displacement effect and regular production of oilfields. In this paper, a new kind of blockage remover has been developed and evaluated by rheological behavior experiments, dissolution experiments and core flooding experiments. The results reveal that this new blockage remover can effectively reduce the viscosity of polymer and completely degrade the reservoir blockage with low corrosion rate. It is beneficial to long-term production of oil wells in offshore oilfield. Results of core flooding experiments show that this new blockage remover can relieve polymer damage and improve permeability. The agent has been applied in LD10-1 oilfield in 2016, the daily injection rate increased significantly after stimulation. Keywords: Polymer injection wells, Formation plugging, Blockage remover, Performance evaluation, Field applicatio

Modeling the Capacitated Multi-Level Lot-Sizing Problem under Time-Varying Environments and a Fix-and-Optimize Solution Approach

In this study, we investigated the time-varying capacitated lot-sizing problem under a fast-changing production environment, where production factors such as the setup costs, inventory-holding costs, production capacities, or even material prices may be subject to continuous changes during the entire planning horizon. Traditional lot-sizing theorems and algorithms, which often assume a constant production environment, are no longer fit for this situation. We analyzed the time-varying environment of today’s agile enterprises and modeled the time-varying setup costs and the time-varying production capacities. Based on these, we presented two mixed-integer linear programming models for the time-varying capacitated single-level lot-sizing problem and the time-varying capacitated multi-level lot-sizing problem, respectively, with considerations on the impact of time-varying environments and dynamic capacity constraints. New properties of these models were analyzed on the solution’s feasibility and optimality. The solution quality was evaluated in terms of the entropy which indicated that the optimized production system had a lower value than that of the unoptimized one. A number of computational experiments were conducted on well-known benchmark problem instances using the AMPL/CPLEX to verify the proposed models and to test the computational effectiveness and efficiency, which showed that the new models are applicable to the time-varying environment. Two of the benchmark problems were updated with new best-known solutions in the experiments