bluuebunny/crossref_metadata_2025 huggingface dataset:
Crack localization in plate-like metallic structures using vibration modulated guided waves
Authors: Hu H F , Shen G J , Yang D X , Zhang S F , Yang Y M , Guan F J
Published: May 2022

This paper proposes a method for crack localization in plate-like metallic structures with nonlinear vibration modulated guided waves. A spatially distributed piezoceramic transducer array is used to introduce a low-frequency modal vibration and a high-frequency ultrasonic tone burst into a metallic plate, and the responses are also acquired by the array. Due to the semi-broadband property and similar propagating speed, the nonlinear waves generated from the damage and the linear waves from other structural features overlap both in time and frequency in the acquired response signals. It is difficult to separate them by filtering method, which affects the damage localization result. The conventional pulse inversion technique is extended to extract the nonlinear signals, and then a delay-and-sum imaging method based on the Wigner-Ville distribution is applied to the extracted signals to construct a damage image. The proposed method is experimentally investigated to localize a fatigue crack near a drilled hole in an aluminium plate. The results demonstrate that the fatigue crack is localized accurately and is also distinguished from linear scatters by use of the proposed method.
The Instantaneous Spectral Entropy for Real-time, Online Structural Health Monitoring.
Authors: Civera Marco , Surace Cecilia
Published: May 2022

Entropy measurements have been recently proposed for the damage assessment of civil structures and mechanical systems. Here, a quasi-real-time approach, based on Instantaneous Spectral Entropy (ISE), is proposed for the detection of sudden stiffness reduction, breathing cracks, and other kinds of structural changes. The method, validated on an experimental benchmark, is suitable for nonstationary signals originating from nonlinear structures as well.
Adaptive Gaussian mixture model based structural damage monitoring method under time-varying conditions
Authors: Fang Fang , Kang Yongle , Qiu Lei , Yuan Shenfang , Yu Kaixi , Xue Zhaopeng
Published: May 2022

The low reliability of damage monitoring under Time-Varying Conditions (TVCs) is a key challenge for the practical application of Structural Health Monitoring (SHM) technology to aircraft structures. Among the existing SHM methods, Guided Wave (GW) and piezoelectric sensor based SHM technique is a promising method due to its high damage sensitivity and long monitoring range. Nevertheless the reliability problem still should be addressed. To deal with this problem, an adaptive Gaussian Mixture Model (GMM) based structural damage monitoring method is proposed. The probability distribution of GW features under TVCs is represented by the GMM. The center of each Gaussian component in a GMM is determined adaptively first. Then a global optimal GMM which could change with TVCs is constructed by the expectation maximization algorithm. Finally, along with damage monitoring process, the variation of GMMs is measured by a probabilistic similarity based damage index which allows normalized detection of structural damage. The utility of the proposed method is validated in the hole-edge crack monitoring of an aluminum tension sample under varying loading condition.
Fault classification based on computer vision for steel wire ropes
Authors: Pan Feiyang , Ren Liyuan , Zhou Jianguo , Liu Zhiliang
Published: May 2022

As an actual steel material application, steel wire rope (SWR) is widely used in various industrial cases. However, in real cases, SWRs are inevitably damaged by erosion, friction, etc. Therefore, it is of great importance to monitor SWRs’ surface conditions in case of accidents. In recent years, computer vision recognition of SWR’s surface has been extensively studied. Based on it, we propose an image-processing method to detect local flaws of SWRs, which extracts the features from the illumination area on the surface of the SWR. Firstly, a three-feature dimension descriptor is constructed by combining the edge grayscale value gradient of the illumination area and morphological features of the illumination area. Then, the KNN (k-nearest neighbour) algorithm is used as a classification method to distinguish the local flaws. According to the experiment results, our proposed method has a high accuracy which is about 94.35%, and low time cost. It can be used in future local flaw detection.
A High Reliability Damage Imaging Method Under Environmental Temperature Variations
Authors: Wu Junpeng , Cai Jian , Yang Jiyuan , Zhang Jian , Zhou Zhiquan
Published: May 2022

In Lamb wave-based structural health monitoring (SHM), the environmental temperature variations can easily affect Lamb wave monitoring signals and seriously reduce the reliability of final damage detection results. To resolve the temperature effect problem, a temperature compensation method of improved baseline signal stretch (IBSS) is presented and applied for high reliability damage imaging under large environmental temperature variations in this paper. After the basic principle of IBSS is analyzed, the realization of IBSS is discussed. Then, a IBSS-based high reliability damage imaging method under temperature variation situation is developed. An experimental study is finally arranged.
Vision-based vibration mode shape extraction for identifying cracks in a cantilever beam
Authors: Deng Rongfeng , Lin Yubin , Li Miaoshuo , Gu Fengshou , Ball Andrew
Published: May 2022

Taking significant merits of high spatial resolution of image sensing, the vibration mode shape of a cantilever beam (CB) is obtained from the free vibration process for local crack identification and structural health monitoring. This vision-based vibration measurement uses a cost-effective rolling shutter camera and a computationally efficient singular value decomposition (SVD). It shows that vibration modes of a continuous structure such as a CB are mainly determined by spatial resolution and less rely on temporal resolution. Moreover, images recorded by the camera maintain the critical information about mode profiles though distortions are introduced into the image. Decomposing the images by SVD allows the vibration modes to be extracted with good degree of accuracy. Both simulation study and experimental verification shows that this novel approach allows different sizes of cracks and locations to be identified.
Investigation of Spur Gear Dynamics with Gear MeshImpacts Induced by Tooth Wear
Authors: Sun Xiuquan , Zhang Ruiliang , Wang Zuolu , Wang Tie , Gu Fengshou , Ball Andrew D. , Liang Bo
Published: May 2022

Tooth wear is one of the most common faults in gear transmission systems. However, due to its limited influences on gear dynamics, the condition monitoring of gear wear experiences more challenges. To investigate the relationship between tooth wear and gear dynamics, this study develops an eight-degree of freedom dynamic model which takes into account the gear mesh impact induced by tooth wear. In this model, the gear mesh impact force induced by tooth wear was calculated as an extra input excitation for the gear dynamic model. Besides, a comparative study was carried out to explore the real reason that causes the poor dynamic behaviour due to the wear from two points of view: 1) the reduction in gear mesh stiffness; 2) the increase in gear mesh impact force. The simulation results show that the wear causes a slight reduction in gear mesh stiffness, thus leading to the decrease in the amplitude of gear mesh frequency. This is not consistent with the phenomena observed in the lab experiment which shows the increase in the gear vibrations. The second simulation of impact force demonstrates that the wear causes an increase in the impact force which further leads to the increase in the amplitude of gear mesh frequency. This study investigates the cause for the deterioration in gear dynamics induced by gear wear, which can benefit the early condition monitoring and fault diagnosis of the gear tooth wear.
Dynamic Characteristics Analysis of a Coupled Multi-crack Rotor System
Authors: Xiong Libo , Hua Chunrong , Yang Funing , Dong Dawei , Ouyang Huajiang
Published: May 2022

This paper establishes a coupled model for multi-crack rotor using Timoshenko beam element with six degrees of freedom, and derives the stiffness matrix in the equations of motion accounting for the coupling between multiple cracks (the interaction between cracks). Then the effects of crack orientation angles (the relative angle between cracks, γ) on dynamic characteristics of the coupled multi- crack rotor near 1/3 and 1/2 subcritical speeds are analysed. The coupling between cracks induces more complex nonlinear dynamic characteristics such as large magnitudes of the super-harmonic components, which can be used as the indicators of early crack and for multi-crack identification. This work has a promotive significance for the application of the model-based method in the field of multi-crack detection of actual rotors.
Debonding detection of scarf-repaired composite laminates with laser ultrasonic Lamb waves
Authors: Xu Yao , Tao Chongcong , Qiu Jinhao
Published: May 2022

In this article, the Lamb wave at low frequency range is chosen to detect the debonding of scarf surface at different depths. The structure of interest is made up of two carbon fiber reinforced laminates with a scarf angle of 5° bonded together by an adhesive film. A 3D finite element model is established to calculate the propagation of Lamb waves with an artificial defect. Based on the wave front of out-of-plane displacement at different timepoint, the debonding area is located when propagating waves convert mode or reduce phase velocity. For validation, experiments are also conducted with wave-visualization technique. Lamb waves are excited by laser ultrasonic system and received by an acoustic emission sensor. The results agree with the simulation ones, which verify that the laser ultrasonic Lamb waves are effective for debond detection on the inclined plane of scarf-repaired composite laminates.
Peridynamic Simulation of Cracking Behavior in Thermal Barrier Coatings
Authors: Wang H , Cai ZW , Wang WZ , Liu YZ
Published: May 2022

Cracking-induced fracture in thermal barrier coatings (TBCs) is one of the most severe failure mechanisms among TBCs failure cases. Current numerical simulation of cracking behavior in TBCs are mostly developed by FEM-based methods, which have their own disadvantages. The concept of peridynamic (PD) is proposed and developed these years to deal with discontinuous problems, providing new ideas to simulate crack initiation and propagation in TBCs. In this paper, a PD-based numerical model of TBCs is built to discuss cracking behavior in the top coat (TC) layer. Simulation results validate the effectiveness and accuracy of PD in TBCs cracking analysis, compared with SEM observations. And effects of pre-existed cracks in TC, which could obviously interfere original crack propagation path, are also proved and discussed. It could be concluded that PD would be a powerful tool in TBCs crack propagation predictions if provided with more supportive experiment data.
Research on Intelligent Vehicle Path Tracking BasedonMPCand Fuzzy Control
Authors: Zhenxin Shi , Yanxue Wang , Jianbo Feng
Published: May 2022

In order to improve the path tracking accuracy of the intelligent vehicle at high speed and establish a practical track tracking controller, this paper based on MPC algorithm, establish a vehicle monorail model, by controlling the front wheel Angle, to achieve the intelligent vehicle to the fifth-order polynomial obstacle avoidance path tracking.With the yaw angular velocity and the error of sidesaw Angle of the center of mass as the double input, the yaw moment is output by the fuzzy controller and applied to the wheel to reduce the deviation of the trajectory under high speed condition.The CarSim/Simulink co-simulation model was built to verify the results, and the results show that the proposed control method can reduce the deviation of path tracking under high speed conditions, and the tracking effect is good.
A tacholess order tracking method based on extended intrinsic chirp component decomposition for gears under large speed variation conditions
Authors: Zhao Hongyang , Jiang Yuan , Niu Gang
Published: May 2022

Order tracking has been considered as the most effective non-stationary signal analysis technique for condition monitoring and fault diagnosis. Conventional order tracking is performed with a reference signal measured by the auxiliary device, which is expensive and inconvenient to install. In order to to break the constraint of the traditional order tracking technique, some tacholess order tracking methods have been developed in the past few years. However, current tacholess order tracking approaches are only applicable to slightly varying speed applications. To overcome the shortcoming above, a novel tacholess order tracking method is proposed in this paper. In the proposed method, each mode of the vibration signal is reconstructed by a method called extended intrinsic chirp component decomposition, and the Hilbert transform is used to estimate the instantaneous phase of reference shaft. Then the vibration signal is resampled to the angle domain, and the fault characteristic orders can be identified in the order spectrum accurately. The effectiveness of the proposed method has been validated by a simulated meshing gear vibration signal. The result illustrates that the proposed method can realize gears fault diagnosis under large speed variation conditions.
Measurement of natural frequency of track based on Bayesian estimation
Authors: Yue Guodong , Dong Jing , Ren Bo , Zhang Xiaochen , Cai Xiaoyong , Li Zhiguang
Published: May 2022

Track modal parameters obtained by the vibration test contain uncertain factors due to the influence of the test environment, the test equipment, the operator, and the simplification of the modal analysis process. In order to estimate the statistical characteristics of the physical parameters of the track, the conjugate prior distribution is selected in the Bayesian estimation method, and the posterior distribution is derived from the experimental data, and the estimated value of the mean and variance of the natural frequency of the track are obtained. The reliability of the method is verified by simulation and experiment. The results show that when only a few samples can be obtained, the full use of prior information and test data can estimate the frequency parameters and reduce the length of the confidence intervals of the mean and the variance. The proposed method has practical reference value in engineering.
Research on Fault Diagnosis of Rolling Bearing Based on SEMSCNN and GRU Model
Authors: Youfu Tang , Teng Wang , Tao Wang , Na Lei
Published: May 2022

In this paper, a deep neural network model fault diagnosis method based on the fusion of SENet-MSCNN and GRU is proposed to address the problem of low diagnosis rate caused by the fact that the normal samples are much larger than the fault samples in the collected rolling bearing vibration big data. The method takes the time-domain vibration signal as input and fuses the spatial features extracted by SE-MSCNN and the temporal features extracted by GRU to bring into the fully connected layer for identification, to realize the intelligent diagnosis of rolling bearing adaptive feature extraction. Finally, the method is applied to the simulated signal and experimental data for testing and analysis respectively. The results show that the model can reach 100% fault recognition rate under variable speed conditions, and at the same time has strong noise immunity, adaptivity and robustness. Thus, providing an effective new way for intelligent diagnosis of rolling bearing vibration big data.
Natural characteristics for transverse vibration of Euler Bernoulli beams with variable end constraints
Authors: Song Shizhe , Dong Dawei , Yan Bing , Xu Fanghui , Huang Yan
Published: May 2022

The transverse vibration of Euler Bernoulli beam with mass of ends and springs is studied. The exact frequency equation is derived and natural frequencies and the corresponding mode shapes are calculated. With the linearly increasing mass of ends, natural frequencies and the rate of frequency change of the beam system initially decrease sharply and then level out, which demonstrates that the beam system is transforming from the free beam to the pinned beam. When the springs are added at two tips, the natural characteristics of the beam are affected by mass of ends and spring stiffness. If the added mass has much lower magnitude than that of the beam, the stiffness of springs exerts major impact on the increase of natural frequencies. While the added mass of ends is increased to the same magnitude of the beam, the natural characteristics of the beam are determined by both the mass of ends and spring stiffness. As the growing magnitude of added mass, mass of ends performs a dominant role in decreasing the natural frequencies. Therefore, spring stiffness and mass of ends should be first considered to establish different dynamic models accurately.
Study on Prognostics and Health Management of Fluid Loop System for Space Application
Authors: Cao Zhi , Zhang Junhua , Li Zhenxiang , Zhao Xin , Guo Dong , Fu Hongyong
Published: May 2022

Prognostics and Health Management (PHM) is an important technical means to realize condition-based maintenance of complex systems. As a complex space application engineering, the space application fluid loop system has the requirements of high safety, high reliability and long life. Therefore, this paper adopts PHM technology to comprehensively study the space application fluid loop system from two aspects of architecture and key technology respectively. Firstly, this paper introduces the current status of health management of fluid loop system for space application and the problems to be solved urgently. Secondly, the PHM system architecture and key technologies such as condition monitoring, health assessment, fault diagnosis, fault prediction and health management are described, and the PHM system research scheme of fluid loop for space application is established. Finally, a case study is carried out by taking the fluid loop main engine of the core power equipment as an example. The analysis results show that the PHM technology can effectively reduce the system failure rate, improve the system safety and reliability, and provide a strong guarantee for the long-term on-orbit operation of the system.
Aerodynamic modelling of a novel vertical axis wind turbine concept
Authors: Morgan Laurence , Leithead William
Published: May 2022

This paper introduces the X-Rotor, a hybrid vertical-horizontal axis turbine concept designed to lower the cost of energy in the floating offshore environment. The development of a double multiple streamtube (DMS) simulation tool is presented alongside a thorough discussion of the secondary correction factors included in the model. New corrections for streamline curvature effects applicable to an airfoil where the blade normal plane is not aligned with the rotor plane are derived.

The DMS model is successfully validated against experimental data and against higher fidelity lifting line (LLT) simulations. Strong agreement is observed between the LLT simulations and the DMS simulations for both rotor averaged and azimuthally varying outputs, indicating that the DMS simulations can be used for future control simulations.
Development of a multi rotor floating offshore system based on vertical axis wind turbines
Authors: Jamieson P , Simao Ferreira C , Dalhoff P , Störtenbecker S , Collu M , Salo E , McMillan D , McMorland J , Morgan L , Buck A
Published: May 2022

The upscaling of wind turbines results in fewer units per installed MW reducing infrastructure and maintenance costs of offshore wind farms. Multi rotor systems (MRS), comprising many wind turbine rotors on a single support structure, are potentially a means to maximize the upscaling benefit in achieving larger unit capacities than is feasible or economic with the conventional, 3-bladed horizontal axis wind turbine (HAWT). The MRS has an inherent upscaling advantage which, for a system with many rotors compared to a single rotor, reduces the total weight and cost of rotor-nacelle assemblies by a large factor. An innovative MRS design is presented based on vertical axis wind turbine (VAWT) rotors of the 2-bladed, H-type. Many disadvantages of VAWT design compared to HAWT in a single rotor system (reduced power performance and higher drive train torque, for example) are resolved in the MRS configuration. In addition, reduced component number and simpler components is advantageous for reliability and O&M cost. This MRS concept has many synergies arising from the choice of VAWT rotors. Results comprise a high-level evaluation of system characteristics and the first stage of more detailed investigation of aerodynamics of the high aspect ratio VAWT.
Development of MOST, a fast simulation model for optimisation of floating offshore wind turbines in Simscape Multibody
Authors: Sirigu M. , Faraggiana E. , Ghigo A. , Bracco G.
Published: May 2022

the paper presents the development of an innovative non-linear, time domain numerical model for the simulation of offshore floating wind turbines, named MOST. The model is able to evaluate the movement of the platform in six degrees of freedom, the power production and the load cycles acting on the blades. MOST is implemented in Matlab-Simulink environment using Simscape Multibody. The aerodynamics is modelled with the blade element momentum theory and the hydrodynamics is modelled using WEC-Sim, a Simscape library developed by NREL and SANDIA. The use of Simscape offers great flexibility to quickly introduce complex dynamic systems such as hybrid wave-wind platforms, flexible platforms, or sea water active ballast systems. Additionally, Matlab provides useful toolboxes and extensive libraries for advanced control systems, linearisation analysis, parallelisation and generation of C code. The results of MOST are then compared to FAST, an open-source code widely used in the academic research. The case study is a 15 MW reference wind turbine installed on the Volturn US platform. The comparison shows a good agreement between the two codes with a significant reduction of the simulation time.
Investigation of manufacturing-related deviations of the bearing clearance on the performance of a conical plain bearing for the application as main bearing in a wind turbine
Authors: Rolink Amadeus , Jacobs Georg , Müller Matthias , Jakobs Timm , Bosse Dennis
Published: May 2022

The use of a segmented conical plain bearing for the application as main bearing in a wind turbine offers multiple advantages. The main bearing can be designed very compact. In addition, in case of a main bearing damage, individual bearing segments can be exchanged on the tower without the use of an external crane, in contrast to the repair procedure of rolling bearings. It is well known from conventional applications of plain bearings that the bearing clearance has a major influence on the load carrying capacity. Therefor the realization of narrow tolerances in the manufacturing of the bearing components is necessary. In this paper, the influence of the manufacturing tolerances on the performance of conical plain bearings is investigated. The influence of the tolerances on the load carrying capacity can be determined by conducting elastohydrodynamic (EHD) simulations. Finally, an evaluation of the robustness of the conical bearing concept against manufacturing-related deviations is carried out.
Validating the next generation of turbine interaction models
Authors: Levick T , Neubert A , Friggo D , Downes P , Ruisi R , Bleeg J
Published: May 2022

It is important to validate turbine interaction models to understand the uncertainties and biases inherent when we model wind farm power output for future wind farms. We present here a repeatable and model-agnostic methodology developed for validating wind farm production models. Power data from the Supervisory Control and Data Acquisition systems of wake-free turbines are used with turbine power curves to generate inlet wind speeds representative of average conditions on the front row of a wind farm. These wind speeds are used, with other model inputs, to run models and predict a modelled power time series for each turbine. The modelled and measured power time series are compared to derive mean bias error metrics. The methodology is applied at 6 offshore wind farms to test established and novel turbine interaction models. We compare the distributions errors predicting power at turbines across models and wind farms. We find that the new models, CFD. ML and the Stratified Eddy Viscosity model, perform well with respect to the established WindFarmer Eddy Viscosity model, and see increased errors for the largest wind farms. We discuss methodological uncertainties in the input wind speed derivation that may cause biases in the overall distributions at windspeeds near the turbine low wind speed cut-in and rated power, and make suggestions for future methodological refinements.
Assessment of Vortex Induced Vibrations on wind turbines
Authors: Manolas Dimitris I. , Chaviaropoulos Panagiotis K. , Riziotis Vasilis A.
Published: May 2022

Modern wind turbines are prone to Vortex Induced Vibrations (VIV). In the present work, an engineering semi-empirical framework is proposed that assesses VIV aero-elastic instabilities of wind turbine configurations. The procedure employs engineering tools relying on airfoil polars. It uses the state-of-the-art aero-elastic tool hGAST along with the EUROCODE VIV framework for steel structures extended to wind turbine configurations. The aero-elastic tool provides the missing modal input data (i.e. modal frequencies, total structural plus aerodynamic modal damping and modeshapes) to evaluate the semi-analytical expressions of the displacement and load amplitudes. Numerical results for single- and two-bladed configurations of the NREL 5MW Reference Wind Turbine (RWT) during assembly are presented, assessing turbine loads under the most unfavourable VIV scenarios examined.
Lifetime extension and opex reduction by adapting the operational strategy of wind farms
Authors: Loepelmann P. , Fischer B.
Published: May 2022

The increasing complexity of the requirements for the operation of wind turbines challanges conventional operating strategies. If revenues are generated from the power exchange, it makes sense to react to price fluctuations during operation. How should such responses be designed? What are the implications for the profitability of wind farm projects from an owner’s perspective? By carrying out a case study, this paper assesses connecting and disconnecting wind turbines depending on electricity prices using economic criteria. The results of the case study show that it is sensible to shut down turbines in economically unfavorable situations. Lost low revenues are recovered by future revenues over a significantly extended lifetime of the turbines, and the profitability of the project increases considerably.
Fast DAQ system with image rejection for axion dark matter searches
Authors: Ahn S. , Lee M.J. , Yi A.K. , Yeo B. , Ko B.R. , Semertzidis Y.K.
Published: May 2022

A fast data acquisition (DAQ) system for axion dark matter
searches utilizing a microwave resonant cavity, also known as axion
haloscope searches, has been developed with a two-channel digitizer
that can sample 16-bit amplitudes at rates up to 180
MSamples/s. First, we realized a practical DAQ efficiency of greater
than 99% for a single DAQ channel, where the DAQ process includes
the online fast Fourier transforms (FFTs). Using an IQ mixer and two
parallel DAQ channels, we then also implemented a software-based
image rejection without losing the DAQ efficiency. This work extends
our continuing effort to improve the figure of merit in axion
haloscope searches, the scanning rate.
Microwave metasurface hologram for holographic imaging and its data encryption applications
Authors: Li Zhenfei , Rukhlenko Ivan D , Zhu Weiren
Published: May 2022

Benefiting from the prominent performance in high-density information storage and fast accessing of two-dimensional data, holography has attracted tremendous attentions. The wavefront recording of traditional holographic devices such as diffraction optical elements suffers from the design complexity and poor resolution as it relies on phase accumulation in the propagating mode, which is achieved by gradually varying the refractive index or thickness of the medium. Ultrathin metasurfaces made of engineered meta-atoms can overcome these limitations owing to their outstanding design flexibility and subwavelength thicknesses. In contrast to the traditional bulky holographic components, the performance of metasurfaces is determined by the electromagnetic response of the meta-atoms with spatially varying in-plane geometric parameters or rotation angles, which enables them to flexibly control the phase, amplitude, wavelength, and polarization of electromagnetic wave. Because of the design flexibility and the capacity of arbitrary wavefront manipulation, metasurfaces are emerging as a promising candidate for holographic memory systems. Here, we review the fast-growing field of metasurface holograms from design principles to recent advances in microwave regime. At the end of the review, we discuss potential applications of the metasurface holography and present a future research outlook.
Microscopic fringe projection profilometry systems in Scheimpflug condition and performance comparison
Authors: Hu Yan , Zheng Kaijie , Liang Zhongwei , Feng Shijie , Zuo Chao
Published: May 2022

The high-frequency fringe images provided by magnifying lenses with low distortion render the microscopic fringe projection profilometry (MFPP) with better measurement accuracy. In order to extend the depth of field limited in the microscopic environment, the Scheimpflug principle is commonly used in both single-camera-based and multi-camera-based MFPP systems by increasing the mutual overlap range of different views in the object space. In this paper, to compare the performance of single-camera-based and dual-camera-based MFPP systems, we set up MFPP systems and performed 3D measurements of plates, standard balls, and some specifically designed samples. By analyzing the various factors affecting measurement accuracy and integrity, we verified and concluded that the dual-camera-based system wins in measurement accuracy while the single-camera-based system has better integrity, which may provide a reference for the system design in the implementation of industrial applications.
A numerical approach to characterize the compression and relaxation behavior of uncured prepreg laminates in the process of hot press-forming
Authors: Li Zhefu , Liu Weiping , Sun Baozhong , Yue Guangquan , Tan Yuan , Zhang Jian
Published: May 2022

In the pre-forming process of uncured prepreg laminates with hot press, the compaction stress is an important parameter that affects the performance and quality of the final product. Therefore, it is necessary to explore the compaction response of the prepreg during manufacturing processes. In this study, the compression and relaxation viscoelastic behaviors of uncured prepreg laminates were investigated in different temperatures, displacements, velocities, and thicknesses. The results show that the power law model and the fractional viscoelastic model could accurately describe the compression and relaxation behaviors, respectively. The theoretical fitting curves match very well with experimental data at each condition and the R-squared value is greater than 0.95. The effect mechanism of compression and relaxation viscoelastic behaviors is analyzed and the obtained results could provide a reference for the process of hot press-forming and numerical simulation.
Kinetochore size scales with chromosome size in bimodal karyotypes of Agavoideae
Authors: Plačková Klára , Zedek František , Schubert Veit , Houben Andreas , Bureš Petr
Published: May 2022

Background and Aims

In eukaryotes, the total kinetochore size (defined as a chromosomal region containing CENH3-positive nucleosomes) per nucleus strongly correlates with genome size, a relationship that has been hypothesized to stem from general intracellular scaling principles. However, if larger chromosomes within a karyotype required larger kinetochores to move properly, it could also be derived from the mechanics of cell division.

Methods

We selected seven species of the plant subfamily Agavoideae whose karyotypes are characterized by the presence of small and very large chromosomes. We visualized the kinetochore regions and chromosomes by immunolabelling with an anti-CENH3 antibody and DAPI (6′-diamidino-2-phenylindole) staining. We then employed 2D widefield and 3D super-resolution microscopy to measure chromosome and kinetochore areas and volumes, respectively. To assess the scaling relationship of kinetochore size to chromosome size inside a karyotype, we log-transformed the data and analysed them with linear mixed models which allowed us to control for the inherent hierarchical structure of the dataset (metaphases within slides and species).

Key Results

We found a positive intra-karyotype relationship between kinetochore and chromosome size. The slope of the regression line of the observed relationship (0.277 for areas, 0.247 for volumes) was very close to the theoretical slope of 0.25 for chromosome width based on the expected physics of chromosome passage through the cytoplasm during cell division. We obtained similar results by reanalysing available data from human and maize.

Conclusions

Our findings suggest that the total kinetochore size to genome size scaling observed across eukaryotes may also originate from the mechanics of cell division. Moreover, the potential causal link between kinetochore and chromosome size indicates that evolutionary mechanisms capable of leading kinetochore size changes to fixation, such as centromere drive, could promote the size evolution of entire chromosomes and genomes.
News in Astronomy & Geophysics – June 2022
Authors: Bowler Sue , Gunn Alastair
Published: May 2022

A digest of some of the big stories from the past two months
On St Teresa of Avila’s mysticism: epilepsy and/or ecstasy?
Authors: Huberfeld Gilles , Pallud Johan , Drouin Emmanuel , Hautecoeur Patrick
Published: May 2022

Saint Teresa of Avila experienced a rich palette of feelings and symptoms precisely documented in her writings. Huberfeld et al. review them, focusing on her ecstasies, in the light of present neurological and psychiatric knowledge, and attempt to differentiate epileptic versus psychological versus mystic manifestations.
Splenectomy modulates the immune response but does not prevent joint inflammation in a mouse model of RA
Authors: Khanfar Esam , Olasz Katalin , Gajdócsi Erzsébet , Jia Xinkai , Berki Timea , Balogh Péter , Boldizsár Ferenc
Published: May 2022

The spleen is the largest secondary lymphoid organ which is involved in the development of B cells and also in systemic (auto)immune responses. Using the recombinant human G1 domain-induced arthritis (GIA) model in splenectomized and control BALB/c mice, we investigated the role of the spleen in the induction and pathogenesis of autoimmune arthritis. Splenectomized mice developed GIA with a similar clinical picture to the control group. However, we observed significant alterations in the humoral and cellular immune responses in splenectomized mice. In the sera of the splenectomized mice, we found lower pro-inflammatory cytokine and anti-rhG1 IgM levels, but higher IL-4, anti-rhG1 IgG1 and anti-CCP and RF antibodies. The arthritis induction in the splenectomized group was associated with a significant expansion of activated helper T cells and an increase in the proportion of the circulating B1 and marginal zone B cell subsets. Importantly, immunization of the splenectomized mice with rhG1 induced the formation of germinal centers in the inguinal- and mesenteric lymph nodes (i/mLNs) which showed an active immune response to rhG1. Finally, both B and T cells from the mLNs of the splenectomized mice showed decreased intracellular Ca2+ signaling than those of the control group. Collectively, these findings indicate that the presence of the spleen is not critical for the induction of GIA, and in its absence the autoimmune arthritis is most likely promoted through the compensatory activity of the i/mLNs. However, our data implies the immunological role of the spleen in arthritis which could be further assessed in human RA.
Associated factors and short-term mortality of early versus late acute kidney injury following on-pump cardiac surgery
Authors: Li Shengnan , Liu Ming , Liu Xiang , Yang Dong , Dong Nianguo , Li Fei
Published: May 2022

OBJECTIVES

Acute kidney injury (AKI) is common following cardiac surgery. The aim was to investigate the characteristics of AKI that occurred within 48 h and during 48 h to 7 days after cardiac surgery.

METHODS

Patient data were extracted from Medical Information Mart for Intensive Care III database. AKI was defined according to the Kidney Disease Improving Global Outcomes guideline and divided into early (within 48 h) and late (during 48 h to 7 days) AKI. Multivariable logistic regression models were established to investigate risk factors for AKI. Cox proportional hazards model was used to analyse 90-day survival.

RESULTS

AKI occurred in 51.2% (2741/5356) patients within the first 7 days following cardiac surgery, with the peak occurrence at 36–48 h. The incidence of early and late AKI was 41.9% and 9.2%, respectively. Patients with late AKI were older and had more comorbidities compared to early AKI patients. Risk factors associated with early AKI included age, body mass index, congestive heart failure and diabetes. While late AKI was related to atrial fibrillation, estimated glomerular filtration rate, sepsis, norepinephrine, mechanical ventilation and packed red blood cell transfusion. In Cox proportional model, both late and early AKIs were independently associated with 90-day mortality, and patients with early AKI had better survival than those with late AKI.

CONCLUSIONS

AKI that occurred earlier was distinguishable from AKI that occurred later after cardiac surgery. Time frame should be taken into consideration.
Effect of preservation solution and distension pressure on saphenous vein’s endothelium
Authors: Pimentel Matheus Duarte , Lobo Filho José Glauco , Lobo Filho Heraldo Guedis , de Castro Miguel Emílio , Pinheiro Paiva Sergimar Kennedy , Silva Matos João Igor , Mesquita Fernandes Matheus Augusto , Fechine Jamacaru Francisco Vagnaldo
Published: May 2022

OBJECTIVES

Approaches to improve saphenous vein (SV) patency in coronary artery bypass graft (CABG) surgery remain relevant. This study aimed to evaluate the effects of different preservation solutions and different pressures of intraluminal distention on the endothelium of SV segments in CABG.

METHODS

Forty-two SV segments obtained from 12 patients undergoing CABG were divided into 7 groups. Group 1 (control) was prepared without preservation or intraluminal distension, while the other 6 groups were preserved in autologous heparinized autologous arterial blood or normal saline (NS), with distention pressures 30, 100 and 300 mmHg. To assess the effects of using these solutions and pressures on the endothelium, the grafts were analysed by scanning electron microscopy, with the measurement of endothelial damage degree.

RESULTS

Segments in group 1 showed minimal endothelial damage. SV grafts preserved with NS had significantly greater endothelial damage both compared to the control group and compared to groups preserved with autologous arterial blood (P < 0.001). Segments distended with pressures up to 100 mmHg showed less damage when compared to those distended at 300 mmHg, with the ones subjected to higher pressures presenting a maximum degree of damage, with considerable loss and separation of endothelial cells, extensive foci of exposure of the basement membrane and numerous fractures of the intimate layer, without differences regarding the solution used.

CONCLUSIONS

Preparation of SV using NS and with intraluminal distension pressures above 100 mmHg is factors related to increased damage to the venous endothelium.
One Full or Two Fractional Doses of Inactivated Poliovirus Vaccine for Catch-up Vaccination in Older Infants: A Randomized Clinical Trial in Bangladesh
Authors: Aziz Asma B , Verma Harish , Jeyaseelan Visalakshi , Yunus Mohammad , Nowrin Samarea , Moore Deborah D , Mainou Bernardo A , Mach Ondrej , Sutter Roland W , Zaman Khalequ
Published: May 2022

Background

The polio eradication endgame called for the removal of trivalent oral poliovirus vaccine (OPV) and introduction of bivalent (types 1 and 3) OPV and inactivated poliovirus vaccine (IPV). However, supply shortages have delayed IPV administration to tens of millions of infants, and immunogenicity data are currently lacking to guide catch-up vaccination policies.

Methods

We conducted an open-label randomized clinical trial assessing 2 interventions, full or fractional-dose IPV (fIPV, one-fifth of IPV), administered at age 9–13 months with a second dose given 2 months later. Serum was collected at days 0, 60, 67, and 90 to assess seroconversion, priming, and antibody titer. None received IPV or poliovirus type 2-containing vaccines before enrolment.

Results

A single fIPV dose at age 9–13 months yielded 75% (95% confidence interval [CI], 6%–82%) seroconversion against type 2, whereas 2 fIPV doses resulted in 100% seroconversion compared with 94% (95% CI, 89%–97%) after a single full dose (P < .001). Two doses of IPV resulted in 100% seroconversion.

Conclusions

Our study confirmed increased IPV immunogenicity when administered at an older age, likely due to reduced interference from maternally derived antibodies. Either 1 full dose of IPV or 2 doses of fIPV could be used to vaccinate missed cohorts, 2 fIPV doses being antigen sparing and more immunogenic.

Clinical Trial Registration

NCT03890497.
Inductive Stimuli of the Startle Response and Critical Points of Psychological Treatment in a Severe Burn Patient
Authors: Zhang Yan , Luo Lun , Li Pan , Chen Zi
Published: May 2022

Severe burn patients often have anxiety, depression, and stress-related disorders. The case we reported was very nervous and exhibited a long-term high-frequency startle response, which disrupted his sleep seriously and decreased treatment compliance. However, after psychological treatment, his startle response in the daytime and nervousness gradually improved, but the startle response at night remained unchanged. Furthermore, after his wife was given three sessions of psychological treatment to manage her fear of surgery, the startle response at night was significantly reduced. Herein, we summarize the inductive stimuli of the startle response and the critical points of psychological treatment in this case to provide the clinical experience for future research.
Impact of HIV on Anal Squamous Cell Carcinoma Rates in the United States, 2001-2015
Authors: Zhang Elizabeth R , Pfeiffer Ruth M , Austin April , Clarke Megan A , Hayes Jennifer , Horner Marie-Josèphe , Monterosso Analise , Pawlish Karen S , Engels Eric A , Shiels Meredith S
Published: May 2022

Background

Incidence of anal squamous cell carcinoma (SCC) has increased in the United States. People living with HIV (PLWH) have an elevated risk of anal SCC, and changes in the number of anal SCCs among PLWH may have influenced general population trends.

Methods

Data were obtained from a linkage of HIV and cancer registries in 12 US regions. The proportion of anal SCCs occurring among PLWH was estimated by sex, age group, and race and ethnicity. To assess the impact of anal SCCs among PLWH on general population trends, annual percent changes (APCs) in incidence rates including and excluding anal SCCs among PLWH were estimated.

Results

Between 2001 and 2015, 14.5% of 16 110 anal SCC diagnoses occurred in PLWH. In 2013-2015, 35% of anal SCCs among men occurred in PLWH, but only 2% among women. The proportion of anal SCCs among PLWH was highest among 20- to 49-year-olds and Black and Hispanic individuals. General population anal SCC trends among men were strongly influenced by anal SCCs among PLWH: rates increased 4.6%/y (95% confidence interval [CI] = 1.4% to 8.0%) from 2001 to 2009 followed by a statistically non-significant decline (APC = −2.7%/y, 95% CI = −7.1% to 2.0%) from 2009 to 2015, but without anal SCCs among PLWH, rates were stable (APC = 0.7%/y, 95% CI = −0.8% to 2.3%). Anal SCC rates among women increased 3.8%/y (95% CI = 3.2% to 4.4%) during 2001-2012 and then declined statistically non-significantly (APC = −3.8%/y, 95% CI = −6.9% to −0.6%), and anal SCCs among PLWH had little impact on these trends.

Conclusions

During 2001-2015, anal SCCs among PLWH contributed strongly to changes in incidence trends in the general US population among men, but not women.
Facing Agoraphobia Situations
Authors: Craske Michelle G. , Barlow David H.
Published: May 2022

This chapter reviews the process of conducting in vivo exposure practices to guide clients in facing agoraphobia situations. Essential throughout all aspects of in vivo exposure is for the therapist to be directive and confident and to encourage clients to continue despite high levels of anxiety. The goal of exposure therapy is not immediate reduction in fear and anxiety; rather, the goal is for the client to learn something new as a result of exposure. If the client’s greatest worry is that fear and anxiety will remain elevated for the entire duration of the practice, then the corrective learning is about the client’s toleration of sustained anxiety. In general, the principle emphasized throughout the treatment is that exposure and cognitive restructuring serve to develop a new set of nonfearful associations between stimulus, response, and meaning. The chapter then considers the inhibitory model of exposure therapy.
Medications
Authors: Craske Michelle G. , Barlow David H.
Published: May 2022

This chapter discusses medications for anxiety and panic. In the workbook, medication is not described as a more or less effective form of treatment in comparison to cognitive behavioral therapy (CBT) but as a more or less appropriate treatment dependent on different beliefs and life circumstances. Medications are described, so that clients may understand their effectiveness and side effects, as well as issues in discontinuing medications. The chapter then details a program to help wean clients from medication as part of an ongoing treatment regimen. In this program, withdrawal effects from medication, particularly benzodiazepines, are managed using the skills taught in the workbook. However, the issue of combining medications with CBT of the sort outlined in this guide and the corresponding workbook is complicated. There is some evidence that benzodiazepines do not combine well with CBT, and there is some evidence that, overall, the combination of medications with CBT is less efficacious in the long term than CBT alone.
Establishing Your Hierarchy of Agoraphobia Situations
Authors: Barlow David H. , Craske Michelle G.
Published: May 2022

This chapter evaluates the process of establishing a hierarchy of agoraphobia situations. Too much anxiety leads to too much avoidance, and avoidance prevents corrective learning. Thus, approaching rather than avoiding situations or experiences is critical to overcoming fear and anxiety. But first, it is necessary to identify the specific situations that one avoids and develop skills to help one to approach those situations. The list should include mildly anxiety-provoking as well as very anxiety-provoking situations. These will be the situations that one will face over and over again in this treatment program. It is also important to identify one’s own unhelpful ways of coping, and to develop lists of superstitious objects, safety signals, distractions, and safety behaviors.