bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficacy of Combining Multiple Electromagnetic Navigation Bronchoscopy Modalities for Diagnosing Lung Nodules
Authors: Song Ju Yeun , Shin Sun Hye , Yoo Hongseok , Jeong Byeong-Ho , Um Sang-Won , Kim Hojoong , Kwon O Jung , Lee Kyungjong
Published: December 2022

Electromagnetic navigation bronchoscopy (ENB) is one of the non-invasive methods used for lung nodule biopsy. We evaluated the efficacy of combining radial endobronchial ultrasound (R-EBUS)-guided transbronchial lung biopsy (TBLB) with ENB-guided TBLB or transbronchial needle aspiration (TBNA) for diagnosing lung nodules. Forty patients with a lung nodule underwent ENB-TBLB or TBNA, followed by R-EBUS-TBLB if available. The final diagnosis was benign or malignant, depending on the surgical pathology or 24-month follow-up computed tomography (CT). We compared the sensitivity, negative predictive value, and accuracy between combinations of procedures. The mean nodule size was 21.65 mm, and 60.0% of the nodules were solid. The bronchus was within the nodule in 67.5% and 65.0% of cases examined using CT and R-EBUS, respectively. The accuracies of ENB-TBLB alone, ENB-TBLB/TBNA, and R-EBUS-TBLB plus ENB-TBLB/TBNA were 74.4%, 82.5%, and 90.0%, respectively. The sensitivity levels of the aforementioned procedures were 69.8%, 78.8%, and 87.9%, respectively. Among 21 patients who underwent both ENB-TBLB and R-EBUS-TBLB, the latter revealed malignant cells in three of nine patients (33.3%) with benign ENB-TBLB results. Combined ENB-TBLB/TBNA and R-EBUS-TBLB had increased sensitivity and diagnostic accuracy for lung nodules. ENB and R-EBUS are complementary; using both modalities improves the sensitivity and accuracy of lung nodule diagnoses.
The Age-Related Course of COVID-19 in Pediatric Patients—1405 Cases in a Single Center
Authors: Stopyra Lidia , Kowalik Aleksandra , Stala Justyna , Majchrzak Ida , Szebla Justyna , Jakosz Mateusz , Kwinta Przemko
Published: December 2022

Since the beginning of the pandemic, many reports have pointed to age as the most important risk factor for severe COVID-19 in adults, but this relationship is less clear in children. Between March 2020 and April 2022, 1405 pediatric COVID-19 patients were included in our prospective study, which aimed to analyze the disease’s characteristics in three age groups: infants, toddlers (1–5 years), and children (5–18 years). We observed male prevalence of the disease in infants and toddlers compared to female prevalence in children. Comorbidities appeared most often in children. In the first pandemic wave, the vast majority of pediatric patients were children, but later, the percentage of infant and toddler patients increased significantly. A total of 74% of hospitalized children were younger than five years. Upper respiratory tract symptoms were most common in infants and toddlers, and lower respiratory tract symptoms and gastroenterocolitis were more common in children. Neurological symptoms appeared similarly in all age groups. The activities of ALT, CK, and LDH were the most elevated in infants, along with D-dimers. The median length of hospitalization fluctuated between three and four days and was highest in infants. Severe courses were more common in adolescents.
Impact of Exercise-Induced Pulmonary Hypertension on Right Ventricular Function and on Worsening of Cardiovascular Risk in HIV Patients
Authors: Madonna Rosalinda , Ridolfi Lorenzo , Morganti Riccardo , Biondi Filippo , Fabiani Silvia , Forniti Arianna , Iapoce Riccardo , De Caterina Raffaele
Published: December 2022

Background and Aim: Exercise-induced pulmonary hypertension (ExPH) predicts clinical outcomes, such as all-cause mortality and cardiovascular (CV) hospitalizations, in patients with dyspnea on effort. We investigated its prognostic significance in human immunodeficiency virus (HIV)-affected patients. Methods: In 52 consecutive HIV patients with either low (n = 47) or intermediate probability (n = 5) of PH at rest, we evaluated—at time 0 and after 2 years—the prognostic determinants of CV risk, according to the 2015 European Society of Cardiology (ESC)/European Respiratory Society (ERS) Guidelines. Patients were classified with or without ExPH at stress echocardiography (ESE) and cardiopulmonary exercise test (CPET). We then related ExPH at time 0 with clinical worsening (CV risk score increase >20% after 2 years). Results: Right ventricle (RV) systolic function was significantly reduced in patients with ExPH compared to those without ExPH at CPET. This also occurred in patients with intermediate/high probability compared to those with low probability of ExPH at ESE. The former exhibited worse values of TAPSE and FAC (p < 0.001 and p = 0.01, respectively). A significantly higher proportion of patients with ExPH (CPET) or with intermediate/high probability of ExPH (ESE) had higher sPAP (p < 0.001), mPAP (p = 0.004) and higher TRV (p = 0.006), as well as higher right atrial area (p < 0.001) and indexed right atrial volume (p = 0.004). Total pulmonary vascular resistance (expressed by the ratio between TRV and the velocity-time integral at the level of the right ventricular outflow tract) was higher both in patients with ExPH and in those with intermediate/high probability of ExPH (p < 0.001). Patients with intermediate/high probability of ExPH at ESE showed a trend (p = 0.137) towards clinical worsening compared to those with low probability of ExPH. No patients with low probability of ExPH had a >20% increased CV risk score after 2 years. We found an association between higher NT-proBNP and the presence or intermediate/high probability of ExPH after 2 years (p = 0.048 at CPET, p = 0.033 at ESE). Conclusions: The assessment of ExPH may predict a trend of increasing CV risk score over time. If confirmed at a longer follow-up, ExPH could contribute to better risk stratification in HIV patients.
Progress in Hematopoietic Stem Cell Transplantation and Cellular Therapies
Authors: Cenariu Diana , Bumbea Horia , Colita Anca , Constantinescu Catalin , Desmirean Minodora , Iluta Sabina , Lysák Daniel , Mussetti Alberto , Tichil Ioana , Tanase Alina , Tomuleasa Ciprian
Published: December 2022

Hematological malignancies are considered to be one of the most important causes of mortality and morbidity in the modern world [...]
Steroid Response after Trabeculectomy—A Randomized Controlled Trial Comparing Dexamethasone to Diclofenac Eye Drops
Authors: Ahmadzadeh Afrouz , Kessel Line , Schmidt Bo Simmendefeldt , Bach-Holm Daniella
Published: December 2022

This prospective randomized controlled trial aimed to compare changes in intraocular pressure in three different anti-inflammatory regimens following trabeculectomy. Sixty-nine patients were randomized to receive either postoperative prophylaxis with topical preservative-free dexamethasone (DEX), diclofenac (DICLO), or their combination (DEX+DICLO). Our main outcome measure was an intraocular pressure (IOP) change of a minimum 4 mmHg following the withdrawal of anti-inflammatory prophylaxis 9 weeks after trabeculectomy. We found that the IOP decreased ≥ 4 mmHg in 18.6% of eyes after cessation of the topical steroid DEX (n = 3/22) and DEX+DICLO (n = 5/21), whereas a decrease in IOP was not observed in the DICLO group. In conclusion, IOP decreased in nearly 1/5 of patients after cessation of topical steroidal anti-inflammatory prophylaxis after trabeculectomy. This points toward a steroid-induced increase in IOP even after trabeculectomy. Thus, increased postoperative IOP may be related to steroid use, and the success or failure of a trabeculectomy cannot be fully evaluated before anti-inflammatory prophylaxis with steroids is stopped or changed to non-steroidal eye drops.
Persistent Inflammation in Cerebral Palsy: Pathogenic Mediator or Comorbidity? A Scoping Review
Authors: Paton Madison C. B. , Finch-Edmondson Megan , Dale Russell C. , Fahey Michael C. , Nold-Petry Claudia A. , Nold Marcel F. , Griffin Alexandra R. , Novak Iona
Published: December 2022

Research has established inflammation in the pathogenesis of brain injury and the risk of developing cerebral palsy (CP). However, it is unclear if inflammation is solely pathogenic and primarily contributes to the acute phase of injury, or if inflammation persists with consequence in CP and may therefore be considered a comorbidity. We conducted a scoping review to identify studies that analyzed inflammatory biomarkers in CP and discuss the role of inflammation in the pathogenesis of CP and/or as a comorbidity. Twelve included studies reported a range of analytes, methods and biomarkers, including indicators of inflammatory status, immune function and genetic changes. The majority of controlled studies concluded that one or more systemic biomarkers of inflammation were significantly different in CP versus controls; most commonly serum or plasma cytokines such as tumor necrosis factor, Interleukin (IL)-6 and IL-10. In addition, differences in inflammation were noted in distinct subgroups of CP (e.g., those with varying severity). The available evidence supports the pathogenic role of inflammation and its ongoing role as a comorbidity of CP. This review shows that inflammation may persist for decades, driving functional impairment across development and into adulthood. However, inflammation is complex, thus further research will increase our understanding.
Coping and Co-Occurrence of Gaming Disorder and Substance Use in Recovering Substance Users
Authors: Burleigh Tyrone L. , Griffiths Mark D. , Sumich Alexander , Wang Grace Y. , Kuss Daria J.
Published: December 2022

Background: There are a wide range of negative effects associated with both substance use disorders and behavioural disorders and their co-occurrence. Understanding the way in which at-risk populations (e.g., substance-abstinent users) interact with potentially addictive behaviours (e.g., gaming) and substance use—while navigating life stressors through differing coping styles—can inform preventative strategies. Methods: Therefore, the present study investigated 64 clinical participants and 138 general population participants. Each cohort was required to complete a battery of psychometric scales exploring problematic behaviours, problematic substance use, co-occurrence, and coping styles. Additional exploratory direct comparisons of gamers in the clinical cohort and gamers in the general cohort were carried out. Results: The study’s findings suggest that gamers from different populations (i.e., general and clinical) share similar at-risk behaviours. These problematic behaviours were more pronounced among abstinent substance use gamers, and more specifically among poly-substance use gamers. Conclusions: The findings of the present study add to the literature and suggest that dysfunctional coping style and the co-occurrence of problematic behaviours may have an impact on the assessment and potential treatment of substance abstinent gamers. The findings offer support for an integrated treatment approach, wherein both substance use and the other problematic behaviours (e.g., gaming) are considered in tandem.
Operational Modal Analysis of Offshore Wind Turbine Tower under Ambient Excitation
Authors: Zhang Peng , He Zhengjie , Cui Chunyi , Ren Liang , Yao Ruqing
Published: December 2022

The condition of an offshore wind turbine (OWT) should be monitored to assure its reliability against various environmental loads and affections. The modal parameters of the OWT can be used as an indicator of its condition. This paper combines the Kalman filter, the random decrement technique (RDT), and the stochastic subspace identification (SSI) methods and proposes an RDT-SSI method to estimate the operational frequency of an OWT subjected to ambient excitation. This method imposes no requirement on the input/loads; therefore, it is relatively easy for field application. An experimental study with a small-scale OWT was conducted to verify the accuracy of the proposed RDT-SSI method. The test results implied that the frequency estimated by the RDT-SSI method is close to that estimated by an impact hammer test. Moreover, the small-scale OWT was buried at different embedment depths to simulate the influence of the scouring phenomenon, and the frequency of the OWT decreased with decreasing embedment depth. Additionally, the bolts at the root of the turbine blades were also loosened to investigate their influence on the frequency. As more blades were loosened, the identified frequency of the OWT also decreased, indicating that the proposed RDT-SSI method can be employed for the health monitoring of an OWT.
A CHEMTAX Study Based on Picoeukaryotic Phytoplankton Pigments and Next-Generation Sequencing Data from the Ulleungdo–Dokdo Marine System of the East Sea (Japan Sea): Improvement of Long-Unresolved Underdetermined Bias
Authors: Hyun Myung Jin , Won Jongseok , Choi Dong Han , Lee Howon , Lee Yeonjung , Lee Charity Mijin , Park Chan Hong , Noh Jae Hoon
Published: December 2022

The CHEMTAX program has been widely used to estimate community composition based on major pigment concentrations in seawater. However, because CHEMTAX is an underdetermined optimization algorithm, underdetermined bias has remained an unsolved problem since its development in 1996. The risk of producing biased results increases when analyzing the picophytoplankton community; therefore, this study tested a new method for avoiding biased CHEMTAX results using the picophytoplankton community around the East Sea (Japan Sea). This method involves building a linear model between pigment concentration data and community composition data based on DNA sequencing to predict the pigment range for each operational taxonomic unit, based on the 95% prediction interval. Finally, the range data are transformed into an initial ratio and ratio limits for CHEMTAX analysis. Three combinations of initial ratios and ratio limits were tested to determine whether the modeled initial ratio and ratio limit could prevent underdetermined bias in the CHEMTAX estimates; these combinations were the modeled initial ratio and ratio limit, the modeled initial ratio with a default ratio limit of 500 s, and an initial ratio from previous research with the default ratio limit. The final ratio and composition data for each combination were compared with Bayesian compositional estimator-based final ratio and composition data, which are robust against underdetermined bias. Only CHEMTAX analysis using the modeled initial ratio and ratio limit was unbiased; all other combinations showed significant signs of bias. Therefore, the findings in this study indicate that ratio limits and the initial ratio are equally important in the CHEMTAX analysis of biased datasets. Moreover, we obtained statistically supported initial ratios and ratio limits through linear modeling of pigment concentrations and 16s rDNA composition data.
A Multi-Model Diagnosis Method for Slowly Varying Faults of Plunger Pump
Authors: Yu Changli , Yan Haodong , Zhang Xingming , Ye Hua
Published: December 2022

As the energy supply component of hydraulic transmission systems, the plunger pump is widely used in the field of ship and ocean engineering. Thus, its fault diagnosis is of great importance. The multi-model fault diagnosis method based on the Kalman filter is slow in detection and isolation in the process of slowly varying fault diagnosis, and it may be diagnosed as a false failure. In this article, to improve the performance of the multi-model fault diagnosis method, we combine the method and support vector machine and propose a new method by fusing the conditional probability of the multi-model with the posterior probability of the support vector machine. The experimental results on a marine plunger pump illustrate the effectiveness of the proposed method. With the appropriate weight coefficient, the detection speed and isolation speed of the joint multi-model method are improved after the combination of the support vector machine, and the new method has better robustness.
Numerical Assessments of Tidal Stream and Wave Energy in Coastal Shelf Seas
Authors: Guillou Nicolas , Lavidas George , Chapalain Georges
Published: December 2022

Tidal stream and wave energy resources may have the potential to complement the exploitation of wind power currently promoted, in industrial countries, as one of the alternatives to fossil fuel energies [...]
The Predictive Role of Systemic Inflammatory Markers in the Development of Acute Kidney Failure and Mortality in Patients with Abdominal Trauma
Authors: Vunvulea Vlad , Budișcă Ovidiu Aurelian , Arbănași Emil Marian , Mureșan Adrian Vasile , Arbănași Eliza Mihaela , Brînzaniuc Klara , Niculescu Raluca , Cocuz Iuliu Gabriel , Ivănescu Adrian Dumitru , Hălmaciu Ioana , Mărginean Lucian , Kaller Réka , Russu Eliza , Suciu Bogdan Andrei
Published: December 2022

Background: Abdominal trauma is defined as a variety of injuries to the abdominal wall, solid or hollow intra-abdominal organs, and various intra-abdominal vessels. Recently, there has been a significant amount of interest in the establishment of a reliable biomarker that can predict the outcome in patients with an abdominal injury. The purpose of this study is to confirm the predictive role of inflammatory biomarkers and underlying risk factors and the risk of acute kidney insufficiency (AKI) developing and mortality in abdominal trauma patients; Materials and methods: The current study was intended as an observational, analytical, retrospective cohort study and included all patients over 18 years of age with a diagnosis of abdominal trauma confirmed through a CT scan admitted to the County Emergency Clinical Hospital of Targu-Mureș, Romania between January 2017, and December 2021; Results: Non-survivor patients had a greater age (p = 0.02), as well as a higher prevalence of ischemic heart disease (IHD) (p = 0.007), history of myocardial infarction (MI) (p = 0.002), peripheral arterial disease (PAD) (p = 0.01), chronic kidney disease (CKD) (p = 0.01), and all risk factors (p = 0.0004 and p < 0.0001). In terms of injured organs, we have in the second group a higher incidence of kidney injury (p = 0.003) and hemoperitoneum (p = 0.008). Multivariate analysis showed a high baseline value for all inflammatory biomarkers that are independent predictors of adverse outcomes for all recruited patients. Furthermore, for all hospitalized patients, the history of MI (p = 0.03; p = 0.001; and p = 0.003), PAD (p = 0.01; p = 0.01; and p = 0.002), obesity (for all p < 0.0001), CKD (p < 0.001; p = 0.01; and p = 0.001), and kidney injury (p = 0.02; p = 0.004; and p = 0.01) were independent predictors of all outcomes. Moreover, IHD (p = 0.008 and p = 0.02), tobacco (p < 0.0001 and p = 0.02), and hemoperitoneum (p = 0.009 and p = 0.01) were predictors of mortality and composite endpoint, but not for AKI risk, as well as atrial fibrillation [AF] (p = 0.04) as predictors of the composite endpoint Conclusions: Higher monocyte to lymphocyte ratio (MLR), platelets to lymphocyte ratio (PLR), systemic inflammatory index (SII), neutrophil to lymphocyte ratios (NLR), aggregate inflammatory systemic index (AISI), and systemic inflammatory response index (SIRI) levels at admission, according to our data, highly predict AKI risk and death.
The Transformation of Fishermen’s Livelihoods in the Context of a Comprehensive Fishing Ban: A Case Study of Datang Village at the Poyang Lake Region, China
Authors: Ma Hongzhi , Zhong Yexi , Ou Minghui , Wang Wenhui , Feng Xinghua
Published: December 2022

How fishermen produce and live has been a hot topic of academic concern in recent years. However, existing research has focused excessively on marine fishermen. Inland fisheries make a significant but often overlooked contribution to rural livelihoods in developing countries. In this paper, we constructed a framework for fishermen’s livelihood strategies and used questionnaires and in-depth interviews to study 275 households of inland fishermen in a professional fishing village at Poyang Lake. The results show that (1) the impact of the comprehensive fishing ban has led to significant changes in the livelihood capital of inland fishermen, leading to fishermen being forced to change their livelihood strategies. (2) The current livelihood strategies can be divided into four categories, which are non-fishing employment, self-employment, public welfare positions and retirement respectively. (3) Livelihood capital such as age, education, social interaction and fishing rights influence their choice of livelihood strategies. (4) The fishing ban proposal generally meets the interests of fishermen, but there is some capacity for improvement in terms of implementation details and policy flexibility. Based on these findings, we recommend that the government conducts further in-depth research and adjusts and improves its policy options in good time. To the satisfaction of all parties, the current policy protects the environment and achieves sustainable human development, making Chinese contributions and proposing Chinese plans to address global environmental change.
Localization of the Urban Planning Process with the Knowledge-Based Sustainable Development Approach
Authors: Abedini Asghar , Aram Farshid , Khalili Amin , Hasanlouei Meysam Saket , Asadi Hiva
Published: December 2022

In recent decades, the concept of a knowledge-based city has been proposed as one of the most important concepts in urban planning. The present study evaluates the ability to localize urban planning indicators in the city of Urmia and determine the desirability of knowledge-based city indicators to provide coherent policies and strategies to achieve sustainable development and a knowledge-based city. Localization is the adaptation of global patterns and methods of development and planning to the internal conditions of the local community. In order to collect data from documents and library studies, experts’ opinions have been used by the Delphi method. Then, indicators related to local urban planning and knowledge-based city were extracted. The present study’s statistical population is 20 specialists and experts related to the research topic through the survey method. In order to analyze the research data, a one-sample t-test was used to assess the ability to localize aspects of urban planning in the city of Urmia. In order to investigate the degree of correlation and factor load of each urban planning indicator, confirmatory factor analysis was used. Using the Swara technique, the desirability and knowledge-based city indicators’ priority level has been evaluated and analyzed. The research results indicate that each of the economic, social, physical, environmental, and managerial aspects of urban planning can be localized in the city of Urmia. Moreover, the situation of Urmia in some aspects is in a situation of incompatibility in terms of the feasibility of the knowledge-based city’s policies. In order to improve the current situation and achieve the desired goals, suggestions have been made in various aspects.
Behavior of Mold Electromagnetic Stirring for Round Bloom Castings and Its Eccentric Stirring Problem
Authors: Wang Pu , Xiao Hong , Zhang Zhuang , Li Shaoxiang , Zhang Jiaquan
Published: December 2022

In this paper, a mold electromagnetic stirring (M-EMS) model was established to investigate the behavior of M-EMS for round bloom castings under different conditions, and an electromagnetic-flow-heat transfer-solidification coupling model was established to explore the problem of eccentric stirring for various formats of round blooms. The results show that the magnetic flux density decreased with the increase in the current frequency, but the electromagnetic torque increases first and then decreases with it, and the same structure of M-EMS for round blooms has the same optimal current frequency at any current intensity. The electromagnetic torque and electromagnetic force both increase as a quadratic function of the current intensity, and the electromagnetic torque, which drives the steel flow, can directly characterize the real M-EMS performance. The mold copper tube has a significant magnetic shielding effect on M-EMS, the stirring intensity decreases rapidly as the tube thickness increases, and the optimal stirring frequency decreases as well. In fact, the deviation between the stirrer center and the geometric center of the strand can result in the eccentric stirring phenomenon. When blooms with a section size of Φ350 mm are produced by Φ650 mm SMS-Concast casting machine, the upper region of the inner arc side and the lower region of the outer arc side are subject to a stronger washing effect, which makes the temperature of the inner and outer arcs show alternating differences. The jet flow from the five-port nozzle can suppress the difference in initial solidification symmetry between the inner and outer arcs of round blooms caused by eccentric stirring. This paper reveals the magnetic shielding effect of the mold copper tube and the magnetic field loss of the air between the stirrer and the inner and outer arcs of the copper, which lead to the stirring intensity and the eccentric stirring phenomenon.
Collagen and Keratin Hydrolysates to Delay the Setting of Gypsum Plaster
Authors: Voinitchi Constantin , Gaidau Carmen , Capatana Tudorie Fanica , Niculescu Mihaela , Stanca Maria , Alexe Cosmin-Andrei
Published: December 2022

Leather and wool waste represent a high concern due to the low level of valorization and circular economy demands for upcycling of biomass resources. Both biomasses can be easily processed as protein hydrolysates and used as functional additives due to the amphiphilic and tunable properties of collagen and keratin proteins. The chemical, physical, and structural investigations of collagen and keratin hydrolysate properties showed that the chelating abilities due to carboxylic groups can be exploited for gypsum retardant additives. The molecular weights and amino acid compositions of three different hydrolysates showed only slight influences on the setting time of gypsum; all three proteins delayed the setting time of gypsum between 60 and 120 min, as compared to the commercial plaster with a 30 min setting time. Higher molecular weight and more carboxylic active groups showed slight improvements in the setting time of mortars. The improved properties of keratin hydrolysate as compared to low molecular collagen hydrolysate were attributed to foaming and conductive properties. The mechanism of mortar setting delaying through calcium ions complexation by protein hydrolysates was shown by electric conductivity evolution of plasters with and without protein additives over time, supported by foaming properties, amino acid, and functional groups’ composition. Lower bending strength values for the higher concentration of proteins do not reduce the potential to use the protein hydrolysates as retardant additives in mortar fabrication.
Experimental Research on Sheared Edge Formation in the Shear-Slitting of Grain-Oriented Electrical Steel Workpieces
Authors: Bohdal Łukasz , Kułakowska Agnieszka , Patyk Radosław , Kułakowski Marcin , Szada-Borzyszkowska Monika , Banaszek Kamil
Published: December 2022

This study sought to experimentally develop guidelines for shaping 0.3-mm-thick cold-rolled grain-oriented ET 110-30LS steel using a shear-slitting operation. Coated and non-coated steel was used for the analysis. The coated sheet had a thin inorganic C-5 coating on both sides applied to the C-2 substrate. The first part of this paper presents an analysis of the quality of the cut surface depending on the adopted machining parameters, which were the control variables on the production lines. The second part presents an analysis of the magnetic parameters of the cut samples, which allowed for the specific impact of the quality of the cut edge on the selected magnetic features. Finally, an optimization task was developed to obtain a set of acceptable solutions on the plane of controllable process variables such as slitting speed and horizontal clearance. The obtained results can be used to control the shear-slitting process on production lines and obtain high-quality workpieces.
Effect of Temperature Cycling Pretreatment on the Thermal Stability of Sm2(Co, Fe, Zr, Cu)17 Magnets in the Mild Temperature Range
Authors: Wu Hulin , Long Zhimei , Li Zhongsheng , Song Kaiqiang , Li Chaoqun , Cong Dalong , Shao Bin , Liu Xiaowei , Sun Jianchun , Ma Yilong
Published: December 2022

The irredeemable magnetic losses of Sm(Co, Fe, Zr, Cu)7.8 permanent magnets caused by oxidation are very important for their practical application. In this work, the simulated results with R2 ≥ 98% based on the data of the temperature cycling test and the long-term isothermal test for the original samples confirmed that the magnetic flux losses reached 9.38% after the 5000th cycle in range R.T.–300 °C, and 7.15% after oxidated at 180 °C for 10 years, respectively. Demagnetization curves showed that the low-temperature oxidation mainly led to the remanence attenuation, while the coercivity remained relatively stable. SEM observation and EDS analysis revealed that an oxide outer layer with a thickness of 1.96 μm was formed on the surface of the original sample at 180 °C for 180 days, in which there was no enrichment or precipitation of metal elements. However, once a Cu, O-rich outer layer with a thickness of 0.72 μm was grown by using a temperature cycling from −50–250 °C for three cycles, the attenuation of magnetic properties could be inhibited under the low-temperature oxidation. This work suggested that the magnetic attenuation of Sm2Co17-type permanent magnets in the low-temperature field could not be ignored, and provided a simple method to suppress this attenuation of magnetic properties below 300 °C.
Acousto–Optic Modulation and Deflection of Terahertz Radiation
Authors: Nikitin Pavel Alekseevich , Gerasimov Vasily Valerievich , Khasanov Ildus Shevketovich
Published: December 2022

It is known that one of the ways to increase the energy efficiency of acousto–optic devices is to use ultrasound beams with a higher power density. It has been established experimentally that the use of a partially electroded ultrasonic transducer significantlyincreases the energy efficiency of the acousto–optic modulator of terahertz radiation. In addition, the operation of an acousto–optic deflector of terahertz radiation with the use of a sectioned ultrasound transducer was theoretically investigated. It showed that a deflector of this kind enables one to achieve higher angular resolution.
Temperature and Infill Density Effects on Thermal, Mechanical and Shape Memory Properties of Polylactic Acid/Poly(ε-caprolactone) Blends for 4D Printing
Authors: Li Ang , Chen Xin-Gang , Zhang Lan-Ying , Zhang Yang-Fei
Published: December 2022

Polylactic acid (PLA)/poly(ε-caprolactone) (PCL) blends have exhibited good shape memory properties and degradable characteristics in various 4D printing fields such as biomedicine, flexible electronics, and soft robotics, where the service temperature fluctuates easily by environment temperature and polymer characteristics. In this work, printed PLA/PCL 4D samples with different infill densities were prepared by material extrusion printing of pre-extruded filaments and characterized under different temperatures. The results show that the microstructures of printed samples are not influenced by printing process and have similar unique orientation as that of filaments. The thermal properties are stable and show obvious phase transition temperatures, while the mechanical properties decrease slightly in low temperature region and then decrease rapidly when temperature is over 60 °C. The increase in infill density can further improve the storage modulus more than 40% and have no significant influence on the thermal properties. The printed samples also exhibit good shape memory performances with fast recovery speeds less than 22 s. Furthermore, a two-step model is provided to predict the effective modulus of printed PLA/PCL samples and agrees well with experimental data. The results prove that temperature and infill density have different influences on the thermal, mechanical and shape memory properties of PLA/PCL blends.
Mesoscale Analysis of the Effect of Interfacial Transition Zone on the Compressive Damage of Concrete Based on Discrete Element Method
Authors: Lei Jian-Jun , Wu Ze-Xiang , Wen Zheng-Jun , Cheng Zi-Shan , Zhu Ran
Published: December 2022

The coarse aggregate–mortar interface transition zone (ITZ) has a great influence on the mechanical properties of concrete, which cannot be easily studied using laboratory tests in the mesoscale. In this paper, a series of axial compression tests were conducted using the discrete element method (DEM) on concrete specimens for four phases: coarse aggregates, mortars, aggregate–mortar interface transition zones, and voids. The effects of ITZ strength on macroscopic stress and microscopic cracks under different strength reduction factors were investigated through axial compression testing. With the increase in interface transition strength, the compressive strength of the concrete becomes stronger; moreover, the number of cracks decreases, and the anisotropy of contact orientation becomes weaker. Meanwhile, the direction of crack development and the damage mode of compressed concrete specimens were also dependent on the coarse aggregate–mortar interface strength coefficient.
Effect of Cu on the Microstructure and Mechanical Properties of a Low-Carbon Martensitic Stainless Steel
Authors: Ma Jun , Song Yuanyuan , Jiang Haichang , Rong Lijian
Published: December 2022

Reversed austenite is of vital importance in low-carbon martensitic stainless steel because it improves impact toughness. However, a proper amount of reversed austenite is obtained by tempering at a critical temperature, which reduces the strength of the steel. Therefore, how to improve strength–toughness matching is an important problem. Copper (Cu) is an effective strengthening element in steels. However, there is little in-depth discussion on the role of Cu on the microstructure and mechanical properties of low-carbon martensite steel. In this work, the effect of different Cu content on the reversed austenite formation, tensile strength, and impact toughness of a low-carbon martensitic stainless steel (0Cr13Ni4Mo) was systematically investigated through use of a transmission electron microscope (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT), and other characterization methods and mechanical property tests. The results showed that the addition of Cu decreased the phase transition temperatures of martensite and austenite and increased the volume fraction of the reversed austenite. APT results indicated that Cu-rich clusters first formed with alloying elements such as ferrum (Fe) and nickel (Ni) and then grew to be precipitates through rejection of the alloying elements. The Ni atoms diffused towards the interface between the precipitates and the martensite matrix, which provided heterogeneous nucleation sites for the reversed austenite. Cu precipitations strengthened tensile strength during tempering. However, it generated temper brittleness in the steel at a tempering temperature of 450 °C, resulting in the impact energy of the 3Cu-steel being only 7 J. A good combination with higher tensile strength (863 MPa) and ductility (192 J) was obtained when tempering at 600 °C in the presence of Cu-rich precipitates and a sufficient volume fraction of the reversed austenite. The results provide guidance for the design of steels with reversed austenite and Cu and promote the development of high-strength and high-toughness steels.
Dynamic Simulation and Parameter Analysis of Harpoon Capturing Space Debris
Authors: Wu Chunbo , Yue Shuai , Shi Wenhui , Li Mengsheng , Du Zhonghua , Liu Zhi
Published: December 2022

This paper aims to study the penetration effect of harpoons on space debris to ensure the sustainable development of the space environment and solve the increasingly serious space debris problem. Firstly, a harpoon system was designed to capture space debris. Secondly, based on the Johnson–Cook dynamic constitutive model and fracture failure criterion, the finite element models of aluminum alloy plates were established. Then, the ballistic limit theory for the aluminum alloy target predicted the minimum launch velocity of the harpoon. Finally, the validation experiment was set up to verify the correctness of the model. The results show that the error between the simulation results of the speed for the harpoon embedded in the target and the theoretical results of the ballistic limit is 9.1%, which provides guidance for active space debris removal technology.
Facile Synthesis of CoOOH Nanorings over Reduced Graphene Oxide and Their Application in the Reduction of p-Nitrophenol
Authors: Chen Huihui , Yang Mei , Yue Jun , Chen Guangwen
Published: December 2022

A facile and one-step route has been employed for the synthesis of highly uniform CoOOH nanorings assembled on the surface of reduced graphene oxide (CoOOH/rGO nanocomposite). The physicochemical properties of the obtained CoOOH/rGO nanocomposite were characterized using X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 physical adsorption (BET) and X-ray photoelectron spectroscopy (XPS). The TEM and SEM results confirmed that CoOOH nanorings (edge length ∼ 95 nm) were uniformly decorated on reduced graphene oxide nanosheets using the simple precipitation–oxidation–reduction method. When used as a catalyst for the reduction of p-nitrophenol to p-aminophenol in the presence of excess NaBH4, the resulting CoOOH/rGO nanocomposite exhibited good activity and stability. When the initial concentration of p-nitrophenol was 1.25 × 10−4 mol·L−1, p-nitrophenol could be fully reduced within 3.25 min at room temperature. The apparent rate constant was estimated to be 1.77 min−1, which is higher than that of pure CoOOH nanorings. Moreover, p-nitrophenol could still be completely reduced within 6 min in the fifth successive cycle. The superior catalytic performance of the nanocomposite is attributed to the synergistic effect between the highly dispersed CoOOH nanorings and the unique surface properties of the reduced graphene oxide nanosheets, which greatly increased the concentration of p-nitrophenol near CoOOH nanorings on reduced graphene oxide surface and improved the local electron density at the interface.
Effect of Mg Powder’s Particle Size on Structure and Mechanical Properties of Ti Foam Synthesized by Space Holder Technique
Authors: Luo Hongjie , Zhao Jiahao , Du Hao , Yin Wei , Qu Yang
Published: December 2022

Titanium foam has been the focus of special attention for its specific structure and potential applications in purification, catalyst substrate, heat exchanger, biomaterial, aerospace and naval industries. However, the liquid-state foaming techniques are difficult to use in fabricating Ti foam because of its high melting temperature and strong chemical reactivity with atmospheric gases. Here, the fabrication of Ti foams via the powder metallurgy route was carried out by utilizing both magnesium powders and magnesium particles as spacer holders, and Ti powders as matrix metal. The green compacts containing Ti powder, Mg powder and Mg particles were heated to a certain temperature to remove the magnesium and obtain the Ti foam. The results show that the porosities of the obtained Ti foam are about 35–65%, and Young’s modulus and yield strength are found to be in the ranges of 22–126 MPa and 0.063–1.18 GPa, respectively. It is found that the magnesium powders play a more important role than the magnesium particles in the deformation and the densification of the green compact during the pressing, and the pore structure of Ti foam depends on the amount and the size of the magnesium spacer holders after sintering.
Impacts of SiC-MOSFET Gate Oxide Degradation on Three-Phase Voltage and Current Source Inverters
Authors: Kim Jaechang , Kwak Sangshin , Choi Seungdeog
Published: December 2022

In this paper, the performance variations of SiC MOSFET-based voltage and current source inverters under gate oxide degradation are studied. It is confirmed that the turn-on and turn-off delays of SiC MOSFETs change significantly by high electric field stress, which accelerates the gate oxide degradation. Variations in the turn-on and turn-off delays of switching devices extend or reduce the duty error of voltage source inverters and current source inverters. The performance variations of the voltage and current source inverter due to the duty error changes caused by the gate oxide degradation are analyzed through simulations. As a result, the gate oxide degradation worsens the performance of the voltage source inverter. Furthermore, the negative gate oxide degradation, which lowers the threshold voltage, decreases the performance of the current source inverter.
Hierarchical Reinforcement Learning for Multi-Objective Real-Time Flexible Scheduling in a Smart Shop Floor
Authors: Chang Jingru , Yu Dong , Zhou Zheng , He Wuwei , Zhang Lipeng
Published: December 2022

With the development of intelligent manufacturing, machine tools are considered the “mothership” of the equipment manufacturing industry, and the associated processing workshops are becoming more high-end, flexible, intelligent, and green. As the core of manufacturing management in a smart shop floor, research into the multi-objective dynamic flexible job shop scheduling problem (MODFJSP) focuses on optimizing scheduling decisions in real time according to changes in the production environment. In this paper, hierarchical reinforcement learning (HRL) is proposed to solve the MODFJSP considering random job arrival, with a focus on achieving the two practical goals of minimizing penalties for earliness and tardiness and reducing total machine load. A two-layer hierarchical architecture is proposed, namely the combination of a double deep Q-network (DDQN) and a dueling DDQN (DDDQN), and state features, actions, and external and internal rewards are designed. Meanwhile, a personal computer-based interaction feature is designed to integrate subjective decision information into the real-time optimization of HRL to obtain a satisfactory compromise. In addition, the proposed HRL framework is applied to multi-objective real-time flexible scheduling in a smart gear production workshop, and the experimental results show that the proposed HRL algorithm outperforms other reinforcement learning (RL) algorithms, metaheuristics, and heuristics in terms of solution quality and generalization and has the added benefit of real-time characteristics.
Modeling and Characteristic Analysis of a Cylinder Block/Valve Plate Interface Oil Film Model for 35 MPa Aviation Piston Pumps
Authors: Wang Tianzhao , Fang Jingjing , Liu Hao , Chen Lijun , Ouyang Xiaoping , Guo Shengrong , Zhao Xiaojun , Lu Yijie
Published: December 2022

Oil film characteristics are critical to the high-reliability operation of high-pressure aviation piston pumps (APPs). However, there is still a lack of research on oil film modeling and characteristic analysis of high-pressure APPs. This paper takes the oil film at the cylinder block/valve plate interface of a 35 MPa high-pressure APP as the research object. By introducing a full oil film computational fluid dynamics (CFD) model considering non-isothermal and cavitation effects under multi-field coupling conditions, a cylinder block/valve plate interface oil film model is established, which includes a viscous wedge geometric model, multi-body dynamics model, and full oil film CFD model. The mesh independence test and force balance error analysis ensure the accuracy of the model calculation. Based on the established model, the oil film’s lubricating, sealing, load-bearing, and overturning characteristics are comprehensively and systematically analyzed, and the evolution law of different oil film characteristics with pressure changes is revealed. Moreover, suggestions for improving the structure and operating conditions of a 35 MPa high-pressure APP are proposed to optimize the oil film characteristics of the cylinder block/valve plate interface.
Real-Time Neural Classifiers for Sensor and Actuator Faults in Three-Phase Induction Motors
Authors: Sanchez Oscar D. , Martinez-Soltero Gabriel , Alvarez Jesus G. , Alanis Alma Y.
Published: December 2022

The main steps involved in a fault-tolerant control (FTC) scheme are the detection of failures, isolation and reconfiguration of control. Fault detection and isolation (FDI) is a topic of interest due to its importance for the controller, since it provides the necessary information to adjust and mitigate the effects of the fault. Generally, the most common failures occur in the actuator or in sensors, so this article proposes a novel model-free scheme for the detection and isolation of sensor and actuator faults of induction motors (IM). The proposed methodology performs the task of detecting and isolating faults over data streams just after the occurrence of the failure of an induction motor (IM), by the occurrence of either disconnection, degradation, failure, or connection damage. Our approach proposes deep neural networks that do not need a nominal model or generate residuals for fault detection, which makes it a useful tool. In addition, the fault-isolation approach is carried out by classifiers that differentiate characteristics independently of the other classifiers. The long short-term memory (LSTM) neural network, bidirectional LSTM, multilayer perceptron and convolutional neural network are used for this task. The proposed sensors’ and actuator’s fault detection and isolation scheme is simple. It can be applied to various problems involving fault detection and isolation schemes. The results show that deep neural networks are a powerful and versatile tool for fault detection and isolation over data streams.
Bootstrapping Not Independent and Not Identically Distributed Data
Authors: Hrba Martin , Maciak Matúš , Peštová Barbora , Pešta Michal
Published: December 2022

Classical normal asymptotics could bring serious pitfalls in statistical inference, because some parameters appearing in the limit distributions are unknown and, moreover, complicated to estimated (from a theoretical as well as computational point of view). Due to this, plenty of stochastic approaches for constructing confidence intervals and testing hypotheses cannot be directly applied. Bootstrap seems to be a plausible alternative. A methodological framework for bootstrapping not independent and not identically distributed data is presented together with theoretical justification of the proposed procedures. Among others, bootstrap laws of large numbers and central limit theorems are provided. The developed methods are utilized in insurance and psychometry.