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1

Application of textual representation methods for clinical numerical data in early sepsis diagnosis

Zhang Weimin, Zhou Luyao, Shao Min, Wang Cui, Wang Yu

International Journal of Applied Mathematics and Computer Science

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2024

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Vol. 34, no. 4

535--548

EN

Sepsis is a severe infectious disease with high incidence and mortality rates worldwide. Early diagnosis of sepsis in newly admitted intensive care unit patients is crucial to reduce mortality and improve patient outcomes. The manual diagnostic methods heavily rely on subjective clinical experience, while traditional machine learning methods require time-consuming feature engineering and the performance is limited by the knowledge acquired from scarce datasets. Therefore, to address the aforementioned issues, this study proposes a novel textual representation method for clinical numerical data, leveraging pre-trained language models from the field of natural language processing for sepsis prediction. Specifically, this study innovatively transforms structured clinical numerical data of patients into unstructured textual descriptions. This transformation reframes sepsis prediction into a text classification task, leveraging the rich prior semantic knowledge embedded in pre-trained language models to enhance prediction performance. The proposed method is validated using real ICU clinical data. When employing RoBERTa-base, it achieved an F1 score of 79.03%, which represents an improvement of five percentage points compared with commonly used machine learning classifiers. The experiments confirmed that the proposed method enhances the performance of early sepsis diagnosis and introduces new insights for clinical diagnosis of sepsis.

2

An in-vitro cell culture system for accurately reproducing the coupled hemodynamic signals at the artery endothelium

Liang Lixue, Wang Xueying, Chen Dong, Wang Yanxia, Luo Xiaoyue, Liu Bo, Wang Yu, Qin Kai-rong

Biocybernetics and Biomedical Engineering

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2024

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Vol. 44, no. 3

501--512

EN

Microfluidics has been an effective technology to reconstruct the in-vivo physiological hemodynamic microenvironment, which is significantly important for preventing and curing circulatory system-related diseases. However, these existing microfluidic systems have failed to accurately reproduce the arterial blood pressure, shear stress, circumferential strain, as well as their coupling relationship, and have not taken into account whether the cells at various locations in the culture chamber are subjected to consistent mechanical stimulation. To solve the above shortcomings, this study developed an in-vitro endothelial cell culture system (ECCS) containing a microfluidic chip and afterload components based on the hemodynamic principles to reappear the desired hemodynamic signals and their coupling relationship accurately, while a relatively uniform area of stress and strain distribution was selected in the microfluidic chip for a more reliable cell mechanobiology study. The sensitivity of global hemodynamic behaviors of the ECCS was analyzed, and numerical simulation and in-vitro experiments were implemented to verify the performance of the proposed ECCS. Finally, the cellular hemodynamic response was tested using human umbilical vein endothelial cells, demonstrating that the proposed in-vitro ECCS has better biological effectiveness. In general, the proposed ECCS in this study provided a more accurate and reliable tool for reproducing the in-vivo hemodynamic microenvironment and showed good potential in the mechanobiology study.

3

Efficient and sensitive quantification of polar tobacco volatile organic compounds by a micro thermal-assisted sampling device using reduced graphene oxide coupling with thermal desorption-gas chromatography/mass spektrometry

Lai Yanhua, Han Bing, Wu Jiahui, Weng Shouhui, Chen Senlin, Wang Junxia, Wang Yu, Pan Xiaowei, Lin Yun, Tao Hong, Zhang Zhuomin, Li Gongke

Acta Chromatographica

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2024

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Vol. 36, no. 3

263--272

EN

It still remains a great challenge to selectively enrich and sensitively quantify the trace volatile organic compounds (VOCs) in real samples with complex matrix. In this study, an integration method combining a selective enrichment medium of reduced graphene oxide (rGO) with a specially designed micro thermal-assisted purge-and-trap sampling device was developed for efficient enrichment and sensitive quantification of trace tobacco VOCs coupling with thermal desorption (TD)-gas chromatography/ mass spectrometry (GC/MS). The prepared rGO has been proved to possess excellent enrichment selectivity and capacity for tobacco polar VOCs with the multi-layer structure, good thermal stability and large specific surface area. The specially designed sampling device was efficient and suitable for enriching and sampling trace polar tobacco VOCs coupling with rGO medium. Under the optimized sampling and analytical conditions, the established analytical method could be actually applied for quantification of typical tobacco polar VOCs with the good recoveries of 72.9–128% and the satisfied RSDs of 1.8–19.9% (n 5 3). The results suggested that the developed method was selective, sensitive and reliable for enrichment and quantification of trace tobacco polar VOCs.

4

Quasi-periodic Inspection and Preventive Maintenance Policy Optimisation for a system with Wiener Process degradation

Gao Wenke, Wang Yu, Zhang Xiwen, Wang Zhuangzhuang

Eksploatacja i Niezawodność

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2023

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Vol. 25, no. 2

art. no. 162433

EN

Periodic inspection policy is performed for some degradation systems to check their degradation states, whereas it is usually difficult to implement on time due to impact of some random factors. Inspections and some maintenance actions are implemented in an inspection window with random, and thus how to optimize the inspection windows and the degradation threshold of the system to perform preventive maintenance (PM) are beneficial in practice. To this end, an optimisation of quasi-periodic inspection and PM policy with inspection window is proposed for a degradation system whose degradation followed Wiener process with a linear drift. Assume that PM can change the degradation rate and inspections are randomly performed in each inspection window. After optimisation, the optimal interval of the inspection window, the degradation threshold of PM and PM policy are determined by minimising the long-term running cost rate of the system. Finally, modeling and optimisation are illustrated using the degradation process of an axial piston pump, and the sensitivity analysis of some key parameters is conducted.

5

Analysis of the cracking mechanisms in pre-cracked sandstone under radial compression by moment tensor analysis of acoustic emissions

Wang Guozhu, Luo Xulin, Song Lei, Wang Yu, Han Mouwang, Song Zhaocun, Wu Linjun, Wang Zukun

Archives of Civil Engineering

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2022

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Vol. 68, nr 3

447--468

EN

Rock masses, especially those with different pre-existing cracks, are prone to instability and failure under tensile loading, resulting in different degrees of engineering disasters. Therefore, to better understand the effect of pre-existing cracks with different dip angles on the tensile instability failure behaviour of rocks, the mechanism of crack initiation, propagation and coalescence in precracked sandstone under radial compression loading is investigated through numerical simulations. The temporal and spatial evolution of acoustic emission (AE) events is investigated by the moment tensor (MT), and the fracture mode of micro-cracks is determined. The results show that the pre-existing cracks weaken the specimens. The strength, crack initiation points and macro-failure modes of the specimens differ significantly depending on the dip angle of the pre-existing crack. For different dip angles of the pre-existing cracks, all the micro-cracks at the crack initiation point are tensile cracks, which are dominant during the whole loading process, and mixed cracks are mainly generated near the upper and lower loading ends after the peak stress. Of the total number of events, more than 75% are tensile cracks; approximately 15% are shear mode cracks; and the remainder consist of mixed mode cracks. The study reveals the instability and failure mechanism of pre-cracked rock, which is of great significance to ensure the long-term stability of rock mass engineering.

6

Primary nonlinear damped natural frequency of dielectric composite beam reinforced with graphene platelets (GPLs)

Qian Qiangfei, Wang Yu, Zhu Fan, Feng Chuang, Yang Jie, Wang Shuguang

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e53, 2022

EN

The present study deals with the primary damped natural frequency of dielectric composite beam reinforced with graphene platelet (GPL). The beam is subjected to pre-stress in the longitudinal direction and external electrical loading throughout the beam thickness direction for tuning the frequency characteristics. The material properties of the composites required for structural analysis are determined by effective medium theory (EMT) and rule of mixture. Using Timoshenko beam theory and Hamilton’s principle, the governing equations for damped nonlinear free vibration of the beam are derived and solved numerically by differential quadrature (DQ) and direct iterative methods. The effects of the attributes of the electrical loading and the GPL fillers on the damped free vibration characteristics are investigated. The analysis shows that when the GPL concentration is greater than the percolation threshold, the voltage of the electrical loading and GPL aspect ratio start to play a vital role in the damped vibration. The nonlinear damped frequency of the hinged-hinged (H–H) beam decreases by 83.8% when the voltage increases from 0 to 30 V. It is found that there exist two critical AC (alternating current) frequencies, i.e., approximate 10−3 Hz and 102 Hz, around which the primary damped natural frequency has a sudden jump as AC frequency either slightly increases or decreases. The vibration characteristics presented demonstrate the potential of developing smart composite structures whose vibration characteristics can be actively tuned by changing the attributes of the applied electrical loading.

7

Bargaining power and U.S. military aid in the post-cold war era

Wang Yu

Security and Defence Quarterly

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2021

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Vol. 35, No. 3

7--23

EN

This study examines the effect of bargaining power on the allocation of U.S. military assistance. Conceptualising U.S. military assistance as an aid-for-policy deal, it applies a two-tiered stochastic frontier model to a data sample of the post-Cold War era. It shows that the bargaining effect accounts for a huge variation in U.S. military aid distribution. The volume of U.S. military assistance in equilibrium is lower than the baseline volume by 4% at the mean and by 6% at the median. The donor U.S. extracts a slightly larger portion of the transaction surplus at these central points. However, the game of surplus division is not always about equally strong hagglers as it may first appear. In fact, the quartile values show substantial variance in bargaining performance and, hence, an outcome of surplus division across transactions. The bargaining effect is highly significant in the allocation of U.S. military assistance in the post-Cold War era. The donor U.S enjoys a bargaining advantage at the mean and median, but rich variations are noticeable.

8

Investigations of mechanical properties of API P110 steel casing tubes operated in deep-sea sour condensate well conditions

Yao Zilin, Wang Yu, Yang Xuefeng, Gao Anping, Zhang Rong, Jia Yanjie

Polish Maritime Research

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2020

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nr 3

121--129

EN

Due to the complexity of the marine environment, in deep-sea drilling, all kinds of strings are corroded by different deepsea conditions for a long time, accompanied by high temperature and high pressure, which lead to the continuous change of mechanical properties of materials. In order to solve the problem that the material mechanical parameters cannot be accurately described in the performance analysis of the casing, deep-sea simulated corrosion and material damage experiments of P110 material were carried out in this paper. Mass loss and tensile experiments on corrosion-damaged test pieces were conducted under different corrosion experimental periods. The changes in mechanical properties of the material were analyzed. Equations of the variation of the equivalent yield strength and the equivalent tensile strength were obtained. The results show that the equivalent yield strength and the equivalent tensile strength decrease with the increase of the weight loss rate. Based on the experimental results and finite element analysis, a method for establishing the material corrosion model was proposed in this paper. The deep-sea drilling corrosion performance model of P110 material was established, which greatly reduced the error caused by the material uniformity assumption in finite element analysis. This paper provides a theoretical basis for the analysis of reliability and life of P110 materials in wells.

9

Tree-ring reconstruction of June-July mean temperatures in the northern Daxing’an Mountains, China

Jiang Yangao, Wang Yu, Zhang Junhui, Han Shijie, Coombs Cassius E.O., Escobedo Maricely, Wang Junwei, Wang Xiaoguang, Hao Lin, Li Guode, Tong Yijiang, Gu Yue, Dong Shengzhong, He Haisheng, Yang Jingyu

Geochronometria

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2020

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Vol. 47, no.1

13--22

EN

In this study, the mean temperature of June to July was reconstructed for the period of 1880 to 2014 by using the Larix gmelinii tree-ring width data for the Mangui region in the northern Daxing’an Mountains, China. The reconstruction accounts for 43.6% of the variance in the temperature observed from AD 1959–2014. During the last 134 years, there were 17 warm years and 17 cold years, which accounted for 12.7% of the total reconstruction years, respectively. Cold episodes occurred throughout 1887–1898 (average value is 14.2°C), while warm episodes occurred during 1994–2014 (15.9°C). Based on this regional study, the warmer events coincided with dry periods and the colder events were consistent with wet conditions. The spatial correlation analyses between the reconstructed series and gridded temperature data revealed that the regional climatic variations were well captured by this study and the reconstruction represented a regional temperature signal for the northern Daxing’an Mountains. In addition, Multi-taper method spectral analysis revealed the existence of significant periodicities in our reconstruction. Significant spectral peaks were found at 29.7, 10.9, 2.5, and 2.2 years. The significant spatial correlations between our temperature reconstruction and the El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Solar activity suggested that the temperature in the Daxing’an Mountains area indicated both local-regional climate signals and global-scale climate changes.

10

The influence of pollution accumulation on coating aging of UHV line insulators with different suspension height in coal-ash polluted area

Lan Lei, Mu Lin, Wang Yu, Yuan Xiaoqing, Wang Wei, Li Zhenghui

Archives of Electrical Engineering

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2020

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Vol. 69, nr 1

39--56

EN

Room temperature vulcanized (RTV) silicone rubber is widely used to prevent pollution flashover with its excellent hydrophobicity and hydrophobicity transfer. However, RTV coatings are at the risk of deterioration and failure in heavily polluted operating environment. In this paper, RTV coated insulators with different suspension heights operating in coal ash polluted areas were sampled. Pollution degree, pollution composition and aging degree of coatings were tested. The result shows that the insoluble pollution contains Al(OH)3 filler precipitated from RTV coating, which indicates the aging of the RTV coating. The top surface coating is more affected by ultraviolet and rainwater than the bottom surface resulting in more serious degradation. As the pollution degree of the lower phase insulator is heavier than that of the upper phase insulator, the erosion effect of pollution on the RTV coating is more intense. The fillers and rubber molecules of RTV continuously precipitate into the pollution layer, leading to further aging. Therefore, the overall aging degree of the lower insulator coating is more serious than that of the upper insulator coating.

11

Availability analysis for a multi-component system with different k-out-of-n:G warm standby subsystems subject to suspended animation

Wang Yu, Guo Linhan, Wen Meilin, Yang Yi

Eksploatacja i Niezawodność

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2019

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Vol. 21, no. 2

289--300

EN

Industrial equipment or systems are usually constructed as a multi-component series system with k-out-of-n:G subsystems to fulfill a specified function. As a common type of standby, warm standby is considered in the multi-component series system with k-outofn:G standby subsystems. When a subsystem fails, the non-failed subsystems are shut off and cannot fail, which is defined as suspended animation (SA). If the SA is ignored the non-failed subsystems are assumed to keep working in the SA time, which will cause inaccuracy in the availability analysis for the system. In this paper, we focus on the SA to construct an availability model for a multi-component series system with k-out-of-n:G warm standby subsystems. Multiple continuous time Markov chains are constructed to model the system availability. A Monte Carlo simulation has been carried out to verify our method. Several interesting findings are obtained. 1) The failure rates of subsystems with SA and their limits are derived. 2) The closed-form expressions for the stationary availability of the system and subsystems, mean time to failure, mean time to repair and stationary failure frequency are obtained considering SA. 3) The system stationary availability is a monotone function for its parameters. 4) The SA effect on the stationary availability should be emphasized in two cases, one is both the value of n/k and the failure rate of active components in a k-out-of-n subsystem are relatively large or small, the other is both the value of n/k and the repair rate are relatively small.

PL

Aby urządzenia i systemy przemysłowe mogły pełnić swoje określone funkcje, zwykle buduje się je w postaci wieloelementowych systemów szeregowych składających się z podsystemów typu k-z-n: G. W pracy rozważano zagadnienie rezerwy ciepłej w wieloelementowym systemie szeregowym składającym się z podsystemów rezerwowych typu k-z-n: G. W przypadku awarii jednego z takich podsystemów, pozostałe, działające podsystemy wyłącza się, dzięki czemu nie mogą one ulec uszkodzeniu. Procedurę taką określa się, przez analogię z organizmami żywymi mianem anabiozy (suspended animation) lub wygaszania. Pominięcie zjawiska wygaszania, prowadzi do założenia, że podsystemy, które nie uległy uszkodzeniu pracują w czasie wygaszenia, co skutkuje nieprawidłowościami w analizie gotowości systemu. W artykule koncepcję wygaszania podsystemów wykorzystano do budowy modelu gotowości wieloelementowego systemu szeregowego składającego się z podsystemów typu k-z-n: G stanowiących rezerwę ciepłą. W celu zamodelowania gotowości systemu, skonstruowano łańcuchy Markowa z czasem ciągłym. Przedstawioną metodę zweryfikowano za pomocą symulacji Monte Carlo. Uzyskano szereg interesujących wyników. 1) Obliczono intensywność uszkodzeń podsystemów wygaszonych i ich wartości graniczne. 2) Wyprowadzono, z uwzględnieniem procedury wygaszania, wyrażenia w postaci zamkniętej dla stacjonarnej gotowości rozważanego systemu i podsystemów oraz określono średni czas do uszkodzenia, średni czas do naprawy oraz stacjonarną częstotliwość uszkodzeń. 3) Gotowość stacjonarna systemu jest funkcją monotoniczną dla parametrów wejściowych systemu. 4) Należy podkreślić wpływ wygaszania na stacjonarną gotowość systemu w dwóch przypadkach: gdy stosunek n/k i intensywność uszkodzeń aktywnych elementów k-tego spośród n podsystemów są względnie niskie lub względnie wysokie, oraz gdy stosunek n/k i intensywność napraw są względnie niskie.