bluuebunny/crossref_metadata_2025 huggingface dataset:
The experience in teaching mathematical disciplines using information technologies
Authors: Demidova Olga , Malinina Nataliya
Published: September 2022

The presented material is devoted to the long-term experiment on the introduction of computer technologies in the process of teaching students of technical (and not only technical) specialties and lectors in various courses and disciplines at MAI. The experiment was carried out in teaching completely different courses, such as: combinatorial analysis, operations research, computational mathematics, as well as in the course of information technology, designed to improve the qualifications of teachers.
Mathematical methods of predicting determining factors characteristics of composites based on generalized durability models
Authors: Gusev Evgeny , Bakulin Vladimir
Published: September 2022

The possibility of creating effective methods for predicting the defining characteristics of composites in refined variational formulations has been investigated. The methodology being developed is based on methods related to the theoretical justification of the admissibility of schemes for narrowing the set of acceptable options, in which the desired globally optimal solution continues to be found on the resulting set of smaller dimensions. Comparative computational experiments were carried out on the basis of the developed methods based on the application of necessary and sufficient extremum conditions. The conducted computational experiments have shown the effectiveness of the developed approach associated with the gradual complication of forecasting models and the corresponding sequential refinement of the optimal parameters of the model.
Stability Analysis of helicopter dynamics with incomplete information using MPC
Authors: Kudryavtseva Irina , Petrov Kirill
Published: September 2022

The paper is devoted to the problem of seeking a helicopter motion control using MPC provided that the state vector is not fully observable. It is supposed that the helicopter motion is described by a dynamic system linearized near regimes with different fixed values of the forward speed. To solve the problem for an arbitrary value of the forward speed the interpolation strategy when the system matrices are decomposed in the basis of the finite functions is used. The proposed technique is applied to analyze dynamic behavior of three models of helicopters: ZD559-Lynx, SA330-Puma, S123-Bo105. The MPC approach permits to gain the stability of helicopters with complete and incomplete information in varying a time interval on which the system is under control and an interval over which a desired output is needed to achieve, initial conditions of a motion and values of the forward speed.
Explosive technologies for testing composite constructions of aircraft for strength to heat-power non-stationary loading
Authors: Ostrik Afanasy , Nikolaev Dmitry , Bakulin Vladimir , Bugay Irina
Published: September 2022

Sets of explosive and heating devices for experimental study of strength of composite constructions of aircraft against complex thermal and mechanical action of radiation and particles fluxes of different physical nature are considered. Two new explosive devices for generating low-pulse loads of microsecond duration are proposed. Devices based on thermoelectric heating elements, conductive plates and pyrotechnic compositions applied to the surface of the tested structure have been developed to simulate thermal action of radiation and particles fluxes. A universal test bench using these sets of devices has been developed. This test bench allows testing the strength of composite constructions to the joint action of thermal and mechanical loads having given space-time distributions.
Representation of the thermo-stress state of a plate based on the 3D elasticity theory
Authors: Revenko Victor , Bakulin Vladimir
Published: September 2022

The general formulation of the 3D temperature static problem of the theory of elasticity is considered. A new representation of the general solution of static equations of thermoelasticity is proposed. The three-dimensional stress state of a thick or thin plate are divided into three parts: bending of the plate, symmetric compression of the plate on it’s flat end surfaces and symmetric temperature problem. Third thermoelastic stress state of the plate is studied in detail. It have been reduced to a two-dimensional state after integration the stresses components along the normal to the middle surface. The displacements and stresses in the plate are expressed in terms of two two-dimensional harmonic functions and a particular solution, which is determined by a given temperature on the flat surfaces of the plate. Only the assumption has been used that the normal stresses perpendicular to the middle surface are insignificant. The introduced harmonic functions are determined from the boundary conditions on the lateral surface of the plate. The formula for the experimental determination of the sum of normal stresses has been found through the measured deflections of the end surfaces of the plate.
Effect of vacuuming on gas-dynamic parameters
Authors: Ruleva Larisa , Solodovnikov Sergey
Published: September 2022

The peculiarity of end-to-end temperature registration on models at the beginning of the experiment, then during high-speed pumping of the test unit into a vacuum and when a high-speed flow is applied to the model is experimentally revealed. The dependence of temperature registration on the vacuum depth and the independence of heat flow registration is shown.
An analytical solution of boundary problems of shell deformation mechanics
Authors: Vinogradov Yuri , Kashfutdinov Bulat
Published: September 2022

This paper proposes an algorithm for the analytical (with a controllable error) solution of boundary-value problems of shell deformation mechanics. Decomposition of partial differential equations is per-formed. The obtained ordinary differential equations in matrix form are solved in the form of converging matrix series in the corresponding coordinates. Atthe point of intersection of the coordinates of ordinary differential equations, the algebraic equations of their connection are satisfied. The error control of the solution of the boundary value problem is carried out by comparing the results when the grid of the de-composition of equations is refined. The study solved the problems of deformation a hinged cylindrical shell and a shallow shell fixed on the edges loaded with external pressure.
Application of an actuator made of a material with a shape memory effect for a transformable space structure
Authors: Zimin Vladimir , Krylov Aleksey , Kuvyrkin Georgy , Shakhverdov Artur
Published: September 2022

Increase in the operational functionality of space technology leads to the necessity of creating large-sized transformable systems. The development of adequate models which are used in computational experiments to simulate the opening of transformable space structures is of great importance. Significant progress has been made in the field of creating large-sized transformable space antennas: the ratio of the mass of the reflector to its working area has decreased to 0.5–1.5 kg/m2. Despite the significant progress achieved in the design of such structures, the task of ensuring smooth and reliable deployment of large-sized transformable space structures, while ensuring their subsequent functioning, remains important. An important area of applied research in the field of shape memory materials is the creation of thermomechanical force actuators that deploy large-sized space structures. Actuators with shape memory effect makes the opening process easy to control, ensuring its shock-free nature. As an active element of the force actuator, it is proposed to use a wire made of titanium nickelide material with a shape memory effect. To develop a functional model of the actuator’s active element made of a shape memory material, a series of experimental and theoretical studies was carried out.
Spinale Muskelatrophie im Erwachsenenalter
Authors: Walter Maggie C. , Hiebeler Miriam
Published: September 2022

Die 5q-assoziierte spinale Muskelatrophie (SMA) ist eine fortschreitende
autosomal rezessive Motoneuronerkrankung mit einer Inzidenz von 1:11 000
Lebendgeburten, die durch den Verlust des Survival Motor Neuron 1-Gens (SMN1)
verursacht wird 1. Additiv zur bisherigen
multidisziplinären supportiven pulmonalen, gastroenterologischen,
orthopädischen, neuropädiatrischen und neuromuskulären
Behandlung wurden in den letzten Jahren 3 bahnbrechende
erkrankungsmodifizierende Therapien der 5q-assoziierten spinalen Muskelatrophie
(SMA) zugelassen, die Phänotypen und Therapielandschaft entscheidend
verändert und damit neue Standards für die Beeinflussung von
Neurodegeneration ermöglicht haben: Nusinersen/Spinraza als
Antisense-Oligonukleotidtherapie, Onasemnogene abeparvovec/Zolgensma als
eine AAV9-basierte Genersatztherapie, und Risdiplam/Evrysdi als ein
„small Molecule Modifier“ des pre-mRNA Splicings.
Qualitätsentwicklung in der Intensivpflege – ein Update
Authors: Friesacher Heiner
Published: September 2022

Was ist eigentlich qualitativ gute Intensivpflege? Der folgende Beitrag geht dieser Frage nach und beschreibt zudem, was Qualität im Handlungsfeld der Intensivstation überhaupt bedeutet und wie komplex die intensivpflegerischen Tätigkeiten mittlerweile sind.
The Accuracy of Hestia and Simplified PESI to Predict the Prognosis in Pulmonary Embolism: Systematic Review with Meta-analysis
Authors: Palas Miguel , Silva Beatriz Valente , Jorge Cláudia , Almeida Ana G. , Pinto Fausto J. , Caldeira Daniel
Published: September 2022

Introduction Pulmonary embolism (PE) patients at low risk of early complications may be considered for early discharge or home treatment. Last decades evidence has been growing about the safety of several clinical prediction rules for selecting those patients, such as simplified Pulmonary Embolism Severity Index (sPESI) and Hestia Criteria. The aim of this review was to compare the safety of both strategies regarding 30-days mortality, venous thromboembolism recurrence and major bleeding.

Methods A systematic literature search was conducted using MEDLINE, CENTRAL and Web of Science on 6th January 2022. We searched for studies that applied both Hestia Criteria and sPESI to the same population. Sensitivity, specificity and diagnostic odds ratio were calculated for both stratification rules. Both Hestia and sPESI criteria of low risk were evaluated to set the number of patients that could be misclassified for each 1000 patients with PE. The estimates were reported with their 95% confidence intervals (95%CI).

Results This systematic review included 3 studies. Only mortality data was able to be pooled. Regarding mortality, the sensitivity, specificity and diagnostic odds ratio was 0.923 (95%CI: 0.843–0.964), 0.338 (95%CI: 0.262–0.423) and 6.120 (95%CI: 2.905–12.890) for Hestia Criteria; and 0.972 (95%CI: 0.917–0.991), 0.269 (95%CI: 0.209–0.338) and 12.738 (95%CI: 3.979–40.774) for sPESI score. The negative predictive values were higher than 0.977. The risk of misclassification of high-risk patients in low risk was 5 (95%CI: 3–11) with Hestia and 2 (95%CI: 1–6) with sPESI, for each 1000 patients with PE in terms of mortality.

Conclusion The risk of misclassification of patients presenting with low-risk pulmonary embolism with the intent of early discharge or home treatment with both Hestia Criteria and sPESI score is low and these data supports methods for this purpose.
The 10th Costal Cartilage Graft in Secondary Cleft Rhinoplasty—A Versatile Rib
Authors: Ujam Atheer B. , Vig Navin , Nasser Nasser
Published: September 2022

Autologous costal cartilage for rhinoplasty is an excellent graft material providing both volume and quality of cartilage required for nasal reconstruction. Commonly, the 5th, 6th, 7th, and 8th rib costal cartilages have been harvested but other ribs such as the 10th rib are often overlooked and yet offer an excellent graft option for columellar, alar rim, nasal tip, and dorsal augmentation grafts. The use of the 10th rib costal cartilage in patients with complex secondary cleft nasal deformity has scant reference in the literature. We demonstrate our simple and quick 10th rib cartilage harvesting technique and elicit its use in secondary rhinoplasty and cleft lip nasal deformities. The advantages of harvesting the 10th rib cartilage and our long-term results demonstrating ease of harvest, stability, and predicable outcomes are with several clinical cases. The senior author has used the 10th rib graft successfully in a variety of challenging secondary cleft rhinoplasty procedures with excellent and consistent outcomes. We advocate the use of the 10th rib graft in such procedures as it is easy to harvest, is a dynamic cartilage graft, and offers predictable results with low levels of complications.
Imaging of Metabolic Bone Diseases: The Spine View, Part I
Authors: Bazzocchi Alberto , Isaac Amanda , Dalili Danoob , Fotiadou Anastasia , Kariki Eleni P. , Kirschke Jan S. , Krestan Christian R. , Messina Carmelo , Oei Edwin H.G. , Phan Catherine M. , Prakash Mahesh , Sabir Nuran , Tagliafico Alberto , Aparisi Francisco , Baum Thomas , Link Thomas M. , Guglielmi Giuseppe , Aparisi Gómez Maria Pilar
Published: September 2022

Metabolic bone diseases comprise a wide spectrum. Of them, osteoporosis is the most frequent and the most commonly found in the spine, with a high impact on health care systems and on morbidity due to vertebral fractures (VFs).

This article discusses state-of-the-art techniques on the imaging of metabolic bone diseases in the spine, from the well-established methods to the latest improvements, recent developments, and future perspectives.

We review the classical features of involvement of metabolic conditions involving the spine. Then we analyze the different imaging techniques for the diagnosis, characterization, and monitoring of metabolic bone disease: dual-energy X-ray absorptiometry (DXA) and DXA-based fracture risk assessment applications or indexes, such as the geometric parameters, Bone Strain Index, and Trabecular Bone Score; quantitative computed tomography; and magnetic resonance and ultrasonography-based techniques, such as radiofrequency echographic multi spectrometry. We also describe the current possibilities of imaging to guide the treatment of VFs secondary to metabolic bone disease.
Imaging of Metabolic Bone Diseases: The Spine View, Part II
Authors: Aparisi Gómez Maria Pilar , Isaac Amanda , Dalili Danoob , Fotiadou Anastasia , Kariki Eleni P. , Kirschke Jan S. , Krestan Christian R , Messina Carmelo , Oei Edwin H.G. , Phan Catherine M. , Prakash Mahesh , Sabir Nuran , Tagliafico Alberto , Aparisi Francisco , Baum Thomas , Link Thomas M. , Guglielmi Giuseppe , Bazzocchi Alberto
Published: September 2022

Metabolic bone diseases comprise a wide spectrum. Osteoporosis, the most frequent, characteristically involves the spine, with a high impact on health care systems and on the morbidity of patients due to the occurrence of vertebral fractures (VFs).

Part II of this review completes an overview of state-of-the-art techniques on the imaging of metabolic bone diseases of the spine, focusing on specific populations and future perspectives. We address the relevance of diagnosis and current status on VF assessment and quantification. We also analyze the diagnostic techniques in the pediatric population and then review the assessment of body composition around the spine and its potential application. We conclude with a discussion of the future of osteoporosis screening, through opportunistic diagnosis and the application of artificial intelligence.
Factors Associated with Pulse Methylprednisolone Treatment Failure in COVID-19-Related Multisystem Inflammatory Syndrome in Children (MIS-C)
Authors: Sugunan Sheeja , Bindusha S. , Niyas H. R. , Geetha S. , Chinchilu R V
Published: September 2022

Objective This article determines the occurrence and variables associated with pulse methylprednisolone treatment failure in children with coronavirus disease 2019 (COVID-19)-related multisystem inflammatory syndrome in children (MIS-C).

Methods This prospective observational study was undertaken at a tertiary care teaching hospital in Kerala, India. Children admitted with COVID-19-related MIS-C who were treated with pulse methylprednisolone as first-line therapy were included in the study. Depending on the response to the treatment, they were divided into two groups. The clinical, laboratory parameters, and follow-up findings at 3 months were compared between the two groups

Results Seventy-six patients were admitted with MIS-C during the study period. Sixty received pulse methylprednisolone as the first-line therapy. Of the 60 patients who received pulse methylprednisolone, 50 responded to treatment, while 10 required repeat immunomodulation. Need for noninvasive or invasive ventilation (relative risk [RR]: 13.14, 95% confidence interval [CI]: 3.147–54.88), six or more organ involvement (RR: 4.667, 95% CI: 1.349–16.149), thrombocytopenia (RR: 6.43, 95% CI: 0.87–47.6, p 0.003), and abnormal chest X-ray findings at admission (RR: 4.5, 95% CI: 1.46–13.8), were found to be associated with increased risk of treatment failure with pulse methylprednisolone therapy. Note that 88% of patients with coronary artery involvement showed resolution at 3-month follow-up.

Conclusion More than 80% of children with MIS-C can be treated successfully with corticosteroids. The need for ventilator support, abnormal chest X-ray findings, and thrombocytopenia at admission were found to be factors associated with pulse methylprednisolone treatment failure.
Evaluation of Cognitive Domain in Objective Exam of Physiotherapy Teaching Program by Using Bloom's Taxonomy
Authors: Zahoor Al-Wardha , Farooqui Sumaira Imran , Khan Amna , Kazmi Syed Abid Mehdi , Qamar Naveed , Rizvi Jaza
Published: September 2022

Objective For the development and growth in conceptual understanding of education, evaluation is one of the key factors of it. Improving a student's cognitive level is highly dependent upon the questions being asked in exams. The primary aim of this study is to analyze the cognitive level of physiotherapy exam papers using Bloom's taxonomy.

Material and Methods The study was performed in a Private Medical University, Doctor of Physical Therapy Program in all 5 years of mid-term examination of 2019. One thousand and eighty multiple-choice questions were evaluated on revised Bloom's taxonomy of cognitive domain.

Results It was found that most lower order cognitive questions were asked from first- and second-year students, whereas third- to fifth-year students were asked higher order cognitive questions ranging from 27.5 to 38%.

Conclusion The examination analyzed the efficacy of education being provided. It helped in finding the subject content that needs greater emphasis and clarification. The faculty should give consideration on higher order cognitive level questions to encourage critical thinking among students and the medical colleges should develop the policy on construction of question papers according to the goal of each study year.
Fatigue among Cancer Patients Receiving Radiation Therapy in a Selected Hospital, Mangalore
Authors: Raju Giya , Crasta Glinivia Reesha , Rodrigues Jane , Johny Jelmol , Dsouza Jelvita , T. Denitha
Published: September 2022

Introduction Cancer is a group of diseases characterized by the uncontrolled proliferation of aberrant cells. Radiation therapy is one of the cancer treatments options. It uses high-energy waves to attack tumor cells, as well as adjacent cells. The majority of cancer patients report feeling tired at the start of treatment or after a few weeks of radiation therapy. It is one of the most disabling and ongoing side effects of anticancer therapy among cancer patients. As a result, cancer-related fatigue can be a troubling symptom for most people getting anticancer treatment which is commonly underdiagnosed by the health care team. This research study aids us in assessing fatigue in cancer patients who receive radiation therapy as a treatment.

Materials and Methods A quantitative descriptive research design was used in this study to collect data from 138 cancer patients who were undergoing radiation therapy both inpatient and outpatient departments of the selected Medical College Hospital in Mangaluru. The samples for this study were chosen using a purposive sampling technique. Data were collected by administering baseline proforma and Fatigue Assessment Scale.

Results Majority of the patients were experiencing substantial fatigue, that is, 105 (76.08%) of patients were experiencing fatigue, 8 (5.79%) were experiencing extreme fatigue. and only 25 (18.11%) were experiencing no fatigue. Mean percentage shows that the majority, that is, 57%, of the patients with cancer experience physical fatigue and 50.25% experience mental fatigue. There is no significant association found between fatigue and selected demographic variables except for marital status (p = 0.015). Hence H0 is accepted at 0.05 level of significance, except for one selected variable.

Conclusion The present study concluded that fatigue is one of the common symptoms and adverse effects experienced among cancer patients who receive radiation therapy. Health care professionals should consider the impact of fatigue on the individual and effective fatigue management to be provided to improve the quality of life
The Study of Spray-Freeze-Drying Technique for Development of Novel Combination pMDIs, Part I: Study on the Preparation Method
Authors: Xi Quan , Miao Jia-Ying , Cao Zhen , Wang Hao
Published: September 2022

Clinically available pressurized metered-dose inhalers (pMDIs) mainly directly use micronized drugs as inhalable microparticles. Although technology for preparing pMDIs has proven to obtain clinically appropriate aerosol performance, the fine particle fraction and delivered dose content uniformity (DDCU) of pMDIs still need to be improved. DDCU problem is usually exacerbated by patients' handling errors prior to taking a dose. In this study, novel phospholipid microparticle inhalation pMDIs were prepared by a spray-freeze-drying process using mometasone furoate and formoterol fumarate dihydrate as model drugs and distearoylphosphatidylcholine as an excipient. Combined with the material composition, the atomization and freeze-drying processes were also studied. Our data showed that both atomization parameters of gas–liquid ratio and freeze-drying curve settings met the requirements of drug design. According to aerodynamic performance in vitro and DDCU evaluation, the performance of the phospholipid microparticle inhalation pMDI was better than that of the micronized drug microparticle pMDI. In conclusion, preparing pMDIs with particle engineering has the potential to ensure accuracy of quantification and to improve the efficiency of drug deposition in lungs in clinical practice.
Social stability risk assessment and economic competitiveness in China
Authors: Zhang Ruilian , Worden Sandy , Xu Junzhuo , Owen John R. , Shi Guoqing
Published: September 2022

Social stability risk assessment (SSRA) has become the mainstream policy instrument for assessing potential risks of large-scale development projects across all sectors in China. In this paper, fuzzy qualitative comparative analysis (fsQCA) is used to quantify the impact of SSRA policy on economic competitiveness across China’s 31 provinces using a SSRA policy dataset (2003–2020) and a provincial economic competitiveness dataset (2019–2020). QCA combines Boolean algebra and set theory to identify configurations of conditions that are necessary or sufficient for a given outcome. Rather than following the mainstream statistical method of developing a single causal model that best fits the data, QCA explores multiple concurrent causality. A typology of SSRA policies was developed to guide our analysis. The research concluded that to support high economic competitiveness within provinces, SSRA policies must be structured around solving social stability problems and addressing a specific industry issue (e.g., pollution) in a particular industry (e.g., resources). Policies that only include one of these factors or that focus on the performance of government officials were found to contribute to low economic competitiveness. Reorienting the focus of SSRA policies could support more rigorous risk assessments and enhance economic competitiveness, particularly in provinces that host large-scale development projects. These findings have implications for China’s policymakers given their dual objectives of driving economic reform while maintaining a harmonious society.
Detection of islands and droplets on smectic films using machine learning
Authors: Hedlund Eric , Hedlund Keith , Green Adam , Chowdhury Ravin , Park Cheol S. , Maclennan Joseph E. , Clark Noel A.
Published: September 2022

Machine learning techniques have been developed to identify inclusions on the surface of freely suspended smectic liquid crystal films imaged by reflected light microscopy. The experimental images are preprocessed using Canny edge detection and then passed to a radial kernel support vector machine (SVM) trained to recognize circular islands and droplets. The SVM is able to identify these objects of interest with an accuracy that far exceeds that of conventional tracking software, especially when the background image is non-uniform or when the target features are in close proximity to one another. This method could be applied to tracking objects in a variety of visually inhomogeneous fluid environments, in order to study growth dynamics, the development of spatial order, and hydrodynamic behavior.
Characterising the woody vegetation in contrasting habitat types in the lower Fitzroy River, Western Australia
Authors: Freestone Fiona L. , Canham Caroline A. , Setterfield Samantha A. , Douglas Michael M. , Beesley Leah S. , Loomes Robyn C.
Published: September 2022

Context Riverine systems consist of distinct habitats along a landscape gradient and characterising the composition and structure of vegetation in these habitats can support environmental water-management decisions. However, in many regions, including northern Australia, there is a paucity of hydro-ecological data. Aims We aimed to characterise the species composition and the structure of riparian and floodplain woody vegetation of the lower Fitzroy River. Methods We surveyed woody vegetation in different habitats within the riparian zone and floodplain. Multivariate analysis was used to assess differences in the composition of riparian woody species among the four habitat types and univariate analysis was used to compare vegetation structure, recruitment, and environmental variables among habitats. Key results The composition and the physical structure of woody species differed among habitat types of the lower Fitzroy River, indicating a zonation of riparian and floodplain vegetation in response to fluvial processes and water availability. The floodplain was characterised by sparsely distributed Eucalyptus microtheca and a sparse (∼30%) canopy cover. In contrast, the riverbank habitat type had very large trees (mean basal area = 0.26 m2), with a dense canopy cover (∼80%) and was dominated by Melaleuca argentea, M. leucadendra and Barringtonia acutangula. Both the top of bank and off-channel wetlands represent a more intermediary environment, characterised by greater species richness and greater seedling recruitment. Conclusions Identifying these habitat types and characterising their physical and biological properties, such as the relationship between flooding and the composition of woody species, provides a framework to assist the management of large floodplain river systems.
Microscope instrument in-flight characterization
Authors: Chhun Ratana , Hardy Emilie , Rodrigues Manuel , Touboul Pierre , Métris Gilles , Bergé Joel , Boulanger Damien , Christophe Bruno , Danto Pascale , Foulon Bernard , Guidotti Pierre-Yves , Huynh Phuong-Anh , Lebat Vincent , Liorzou Françoise , Robert Alain
Published: September 2022

Since the MICROSCOPE instrument aims to measure accelerations as low as a few 10−15 m s−2 and cannot operate on ground, it was necessary to have a large time dedicated to its characterization in flight. After its release and first operation, the characterization experiments covered all the aspects of the instrument design in order to consolidate the scientific measurements and the subsequent conclusions drawn from them. Over the course of the mission we validated the servo-control and even updated the PID control laws for each inertial sensor. Thanks to several dedicated experiments and the analysis of the instrument sensitivities, we have been able to identify a number of instrument characteristics such as biases, gold wire and electrostatic stiffnesses, non linearities, couplings and free motion ranges of the test-masses, which may first impact the scientific objective and secondly the analysis of the instrument good operation.
Biased self-diffusion on Cu surface due to electric field gradients
Authors: Kimari Jyri , Wang Ye , Kyritsakis Andreas , Zadin Veronika , Djurabekova Flyura
Published: September 2022

Under strong electric fields, an arc of strong current flowing through plasma can link two metal surfaces even in ultra high vacuum. Despite decades of research, the chain of events leading to vacuum arc breakdowns is hitherto unknown. Previously we showed that a tall and sharp Cu nanotip exposed to strong electric fields heats up by field emission currents and eventually melts, evaporating neutral atoms that can contribute to plasma buildup. In this work, we investigate by means of molecular dynamics (MD) simulations whether surface diffusion biased by the presence of an electric field gradient can provide sufficient mass transport of atoms toward the top of the nanotip to maintain supply of neutrals for feeding plasma. To reach the necessary timescales and to add electric field in MD, we utilized a novel combination of collective variable-driven hyperdynamics acceleration and coupling to a finite element mesh. In our simulations, we observed biased self-diffusion on Cu surfaces, that can contribute to the continuous replenishment of particle-emitting nanotips. This mechanism implies a need to reduce the rate of surface diffusion in devices that are susceptible to vacuum arcs. Finding suitable alloys or surface treatments that hinder the observed biased diffusion could guide the design of future devices, and greatly improve their efficiency.
The influence of contact metals on epitaxially grown molybdenum disulfide for electrical and optical device applications
Authors: Tsai Po-Cheng , Yan Coung-Ru , Chang Shoou-Jinn , Lin Shih-Yen
Published: September 2022

Bottom-gate transistors with mono-layer MoS2 channels and polycrystalline antimonene source/drain contact electrodes deposited at 75 °C are fabricated. Significant performance enhancement of field-effect mobility 11.80 cm2 V−1·s−1 and >106 ON/OFF ratio are observed for the device. Increasing photocurrents are also observed for the MoS2 transistor under light irradiation, which is attributed to the reduced carrier recombination at the metal/2D material interfaces. The results have demonstrated that besides the matching of work function values with the 2D material channel, the crystallinity of the contact electrodes is the other important parameter for the Ohmic contact formation of 2D material devices.
Reflectivity of Different Texturing Structures Fabricated by Femtosecond Laser Etching
Authors: Liang Long , Liu Wenwen
Published: September 2022

Femtosecond laser etching is applied to fabricate cylindrical, quadrangular and circular hole micro-structures to explore the variation patterns of their reflectivity. The results show that the cylindrical and quadrangular texturing structures have the optimal anti-reflection effect (the reflectivity is always below 6%) in the wavelength range of 350-1000 nm, which is of reference value for the study of fabricating low-reflectivity texturing on monocrystalline silicon surfaces.
Analysis of piping and support weld defects of VVP system in nuclear power plant and study on treatment measures
Authors: Li Cheng
Published: September 2022

The main steam system(VVP) support of nuclear power plant protects the main pipe by welding the guard plate on the main pipe. This paper takes defect treatment of the VVP main steam system(VVP) pipe and support weld in a nuclear power plant as an example. From the analysis of the effective mechanism of the weld generation to the proposal, discussion and implementation of the final scheme, the technical points are comprehensive described, defect types were determined by penetrant testing and metallographic observation, and further root reason analysis was carried out. Accordingly, the defects are eliminated by technical means to avoid the expansion of defects and ensure the safe and stable operation of the unit. The analysis and treatment scheme of the defects in this project provides a technical scheme for inspection and maintenance in the nuclear power field, and provides an important reference for the future treatment of defects.
Research on Sealing Assembly and Adjustment Method of Assembled Cabin Door of Space Station
Authors: Liu Shufen , Zhang Bin , Wang Tianming , Yi Zhuoxun , Huang Ning , Cui Xiaohang , Zhang Xun , Yu Junyu
Published: September 2022

For the new assembled sealed cabin door of space station, its structural characteristics, sealing working principle and sealing assembly and adjustment difficulties are analyzed. The static simulation based on the minimum loading point deformation is studied to obtain the minimum compression ratio boundary. Based on the maximum operating force, the sealing stress calculation and simulation analysis are carried out to obtain the maximum compression rate boundary. It realizes the transformation of multiple open constraints into the compression rate interval, which effectively improves the assembly and adjustment accuracy and efficiency of the assembled cabin door.
Analysis of Austempering Characteristics of Cr12MoV Die Steel
Authors: Wang Huizhen , Zhai Yuewen , Zhou Leyu , Zhang Zibo , Liu Bo
Published: September 2022

The characteristics of microstructure and properties of Cr12MoV die steel with austempering were investigated by scanning electron microscope, electron backscattered scattering detection, X-ray diffractometer and Rockwell hardness tester. The results indicated that the tempering process reduced retained austenite apparently, especially after direct quenching process which decreased the volume fraction of retained austenite from 24.8% to 8.5%. Prolonging the holding time of isothermal quenching from 3h to 5h promoted the transformation of lower bainite and reduced the content of residual austenite. The bainite formed in isothermal combined with the secondary hardening caused by austenite decomposition made the hardness of 55.9-56.6HRC similar to that of 57.2HRC by direct quenching and tempering.
Effect of heat treatment process on microstructure and hardness of Ni48Co30Cr16Al3Ti3 high entropy alloy
Authors: Li Xin , Wang Chenglei , Zhang Zhenjun , Tan Hong , Xie Yingguang , Qin Haiqing , Liu Chong , Liang Mulin , Liu Weijie , Yang Jijie
Published: September 2022

Ni48Co30Cr16Al3Ti3 HEA was made by suspension melting, and treated by different heat treatment methods. The microstructure, phase composition and microhardness of the prepared alloy samples were analyzed by means of XRD, SEM, X-ray energy spectrum analyzer and microhardness tester. And the results show that the Ni48Co30Cr16Al3Ti3 HEA after different heat treatments has face centered cubic structure, and the alloy structure presents dendrite morphology. Under different heat treatment conditions, the diffraction peaks of the alloy samples treated by secondary aging at (800°C×12h+1000°C×4h) are the highest and strongest, and the precipitates of the alloy samples treated by aging at (800°C×12h) are the most dense and subtle. The distribution of elements in the samples are relatively uniform, but after heat treatments, part of the alloy grain structure and grain boundaries dissolve, the degree of dissolution increases with the increase of heat treatment time, so that some elements are not distributed in the alloy structure and grain boundaries. The microhardness value of alloy samples first increases and then decreases with the prolongation of heat treatment time, and the microhardness values of the samples were the highest after aging treatment at (800°C×12h), which was 357HV1.
Charge density wave in low dimensional materials
Authors: Zhu Hua , Han Hui
Published: September 2022

Charge density wave(CDW) is an important physical phenomenon and has always been one of the significant research contents in condensed matter physics. The study of CDW helps people to have a deeper understanding of the interactions between various particles in low-dimensional systems. At the same time, the control of CDW in the material can effectively control the physical properties such as superconductivity. The study of CDW originated from one-dimensional and quasi-one-dimensional materials. This paper introduces the origin of CDW and the main formation mechanism of CDW at this stage. Discuss the common regulation methods of CDW and the competitive relationship with other physical properties. Finally, the possible research directions in related fields and the potential applications of CDW are prospected.
Research on Surface Quality of 38CrMoAl Polished Based on Abrasive Water Jet
Authors: Wang Jiasheng , Yuan Yuefeng , Xie Fei
Published: September 2022

Because the screw surface is slender and complex, it is difficult to process by traditional polishing methods. In order to improve the surface quality of screw, the abrasive water jet polishing (AWJP) technology was used to polish 38CrMoAl steel, which is commonly used in screw. The effects of different inlet pressure, target distance and abrasive particle size on surface roughness are analyzed. The experimental results show that with the increase of inlet pressure, the surface roughness first decreases and then increases. With the increase of target distance, the surface roughness first decreases and then increases. The smaller the abrasive particle size, the better the polishing effect.
Fluorinated poly(aryl ether nitrile)s containing pendant cyclohexyl groups toward low k materials
Authors: Liu Chenchen , Liu Shuning , Feng Xiaofang , Bai Zhongxiang , Lin Guo , Xia Yunqing , Wang Lingling , Liu Xiaobo
Published: September 2022

To obtain low k materials with good comprehensive performances, fluorinated poly(aryl ether nitrile)s containing pendant cyclohexyl groups (FCPEN) have been designed and synthesized via nucleophilic aromatic substitution polymerization. The polymer exhibits excellent dielectric properties with a dielectric constant of 2.96 and a dielectric loss of 3.95 × 10-3 at at 1 MHz. Besides, FCPEN displays satisfactory thermostability with a 5% weight loss temperature (T
d5%) of 489 °C and a glass transition temperature (T
g) of 191 °C. The resultant film shows good mechanical performance and optical transmittance. The outstanding comprehensive properties indicate that FCPEN is a promising low k material for the fabrication of microelectronic devices used in 5G communication.
Enhancing the dielectric properties of poly (arylene ether nitrile) by introducing co-modified BaTiO3
Authors: Xia Yunqing , Lin Guo , Liu Chenchen , Bai Zhongxiang , Liu Shuning , Liu Xiaobo
Published: September 2022

In this study, a facile co-modification of dopamine (DA) and methylphenyldimethoxysilane (MPDS) was utilized to functionalize barium titanate (BaTiO3) nanoparticles with organic functional film. With the organic film coated on surface of BaTiO3, the compatibility between BaTiO3 and PEN matrix was greatly enhanced, which led to the promotion in thermal and dielectric properties. Results indicated that the glass transition temperature (Tg) of BaTiO3@(MPDS+PDA)/PEN composite showed increment from 171.9°C to 181.2°C. Besides, the dielectric constant of PEN composite containing 20 wt.% of BaTiO3@(MPDS+PDA) improved to 9.32 with a relative low dielectric loss compared to BaTiO3/PEN under the same additive ratio.
Effect of Ce addition on microstructure and hardness of (Ni2CoFe)86Ti8Al6 high entropy alloy
Authors: Liu Chong , Wang Chenglei , Zhang Zhenjun , Tan Hong , Xie Yingguang , Qin Haiqing , Li Xin , Liang Mulin , Liu Weijie , Yang Jijie
Published: September 2022

The effects of different Ce contents on the microstructure and hardness of (Ni2CoFe)86-xTi8Al6Cex (x = 0, 0.1, 0.3, 0.5, 0.7, 1.0 molar ratio) high entropy alloys were systematically studied. The results show that the addition of Ce promotes the precipitation of new FCC and BCC phases. The precipitates were promoted by Ce, and the grains and structures were refined by Ce. With the gradual increase of Ce content, the hardness gradually increases. The microhardness (HV) of (Ni2CoFe)85Ti8Al6Ce HEA is 458.6. The increase of precipitate volume fraction and fine grain strengthening are the main reasons for the increase of hardness.
Research on system identification method of buffer system based on experimental signal pre-processing
Authors: Yu Bin , Tan Ruoyu , Zheng Jieji , Li Baoyu , Fan Dapeng , Xie Xin
Published: September 2022

In order to obtain the theoretical model of a gun buffer system, the dynamic vibration characteristics of the buffer system were studied by force hammer experiments, and the vibration acceleration response curves of the buffer system after being excited by the impact load were obtained. The acquired signals were processed by noise reduction, detrending, data smoothing and frequency domain integration, and the second-order free vibration model was used to identify the stiffness, damping and other parameters of the system, and compared with the experimental results. The deviation between the calculated results of the identification model and the experimental results is less than 4%, which compared with the general direct identification method, the error is reduced by about 10%. This method can provide a simple and fast technical way for the accurate identification of vibration system models.
The Design Theory of the Shaving Cutter of Conjugate Curved Gears
Authors: Zhu Jiao , Zhang Luhe , Tang Yu , Chen Bingkui
Published: September 2022

Based on the existing research on the conjugate curve gear, the meshing equation of the shaving process is deduced according to the gear meshing principle and the working principle of the disc shaving cutter, so as to obtain the tooth surface equation of the shaving cutter corresponding to the conjugate curve gear, which provides a theoretical basis for the design of the shaving cutter of the conjugate curve gear.
Lightweight design of brake callipers based on OSF response surface algorithm
Authors: Zhang TongShuai , Chen XiuSheng , Zhang LiangZheng , Song JiuLing , Sun WenXue
Published: September 2022

In this paper, ANSYS Workbench software is used to establish the brake caliper finite element model, finite element analysis of the model. Under the premise of satisfying the strength, stiffness and stability of the caliper model, Workbench DesignXplorer module was used to optimize the caliper parts' dimensions, and a two-level response surface model was constructed based on OSF algorithm. The caliper mass was taken as the main output parameter, and the lightweight design was carried out through MOGA multi-objective optimization. In terms of material lightweight, new vermicular cast iron was selected to replace QT450, QT600 and Q235 materials. After lightweight design, the yield strength and tension and compression strength of calipers were satisfied, and the mass was reduced by 15.4%
Research on Power Load Prediction Based on Elman Network with Improved Particle Swarm Optimization
Authors: Liu Shijian , Zhang Li , Xia Huiwen
Published: September 2022

Because electricity is so difficult to store, the electric power department needs to store enough power in advance, whether customers use it or not. To lower the cost of the electric power department in this aspect, it is essential to realize high-precision power load forecasting. The Elman neural network (ElmanNN) prediction model based on the improved Particle Swarm Optimization (IPSO) algorithm is constructed. The Particle Swarm Optimization (PSO) algorithm is brought in, and the learning factor of the algorithm is optimized for the limitation that the PSO algorithm can easily obtain the local optimal solution. Finally, the improved algorithm is applied to the ElmanNN. The improved ElmanNN solves the problems of slow training speed and is effortless to obtain the local minimum. Finally, simulation experiments verify that the ElmanNN model based on the improved PSO algorithm has a smaller prediction error in power load prediction.
Dynamic model of fine-pitch gear pair considering multi-clearance coupling
Authors: Zeng Xi , Zhang Luhe , Tang Yu , Li Zhaoyang , Chen Bingkui
Published: September 2022

In this paper, the parallel shaft fine-pitch involute plastic-powder metallurgy engagement spur gear pair produced according to the recommended backlash value of DIN standard is taken as research object. The coupling between the backlash and the bearing radial clearance is considered. And the expression of the dynamic backlash is derived. A three-degree-of-freedom two-state dynamic mathematical model of the parallel shaft gear transmission system is established. The time-domain curves of gear displacement, velocity, engagement force and dynamic backlash are obtained. The results of mathematical model show that a larger backlash range than DIN standard recommended is more conducive to smooth transmission.
Research on multi-cylinder synchronous control system of multi-directional forging hydraulic press
Authors: Xu Cong , Xu Xiao , Liu Zhao , wang Xin
Published: September 2022

A master-slave synchronization control strategy based on RBF network adaptive sliding mode control is proposed to solve the problem of lack of effective control strategy and control accuracy in the process of synchronous motion of three horizontal cylinders of multi-directional die forging hydraulic press in VL ball cage forming process. According to the high-order nonlinear mathematical model of the single-cylinder electro-hydraulic servo system, the RBF network adaptive sliding mode controller is designed. The joint simulation model is established by using AMEsim and MATLAB to solve the tracking accuracy and synchronous control accuracy of the system, and the control effect is verified by comparing with the conventional PID control. The simulation results show that the RBF network adaptive sliding mode controller has strong robustness, and the three horizontal cylinder displacement synchronization controllers of the multi-directional die forging press designed in this paper have good synchronization performance.