Search

To address the low accuracy of conventional bearing fault diagnosis methods that rely on empirical parameters in the scenarios with different noise degrees, this paper presents an adaptive bearing fault diagnosis method combining empirical mode decomposition (EMD) and tile coding. Firstly, the mature adaptive decomposition algorithm, namely the EMD, was employed to decompose the bearing vibration signal. Based on specific criteria, some components were selected as effective signals and further denoised based on spectral averaging to realize adaptive filtering of the bearing vibration signal. Secondly, feature extraction of the filtered signal was conducted using spectral coding based on tile coding. The coding results were input into the K-nearest neighbors (KNN) classifier as features. Finally, for validation, a test dataset with varying noise degrees was constructed to conduct a comparison between the proposed adaptive method and the classic adaptive filtering-based fault diagnosis methods. The results show that when the signal-to-noise ratio is greater than －10 dB, the diagnostic accuracy of the proposed approach exceeds 90% and outperforms that of other methods.

During the daily operation of locomotive, affected by the locomotive itself and external environmental factors, the height of the sand pipe may change, which will lead to wheel slippage failure in severe cases, resulting in safety problems. Therefore, a sand pipe height measurement algorithm based on deep learning is proposed in this paper. Firstly, the object detection of sand pipe in 2D image and the fitting segmentation of rail plane were realized through the deep-learning-based YOLOv3-tiny algorithm and DeepLabv3+ model. Secondly, for the noise point cloud in the measurement environment, this paper implements point cloud filtering through depth value filtering and clustering segmentation. For the foreign matters on the sand pipe that affect the height measurement, the edge extraction and false edge removal are designed to eliminate the influence of foreign matters on the measurement accuracy. Finally, the rail plane is fitted by RANSAC algorithm to achieve 3D high-precision measurement of sand pipe height. Using the proposed algorithm and a 10-division vernier caliper, a comparative experiment is conducted on the height measurement of sand pipes with different positions, shapes and light intensities. The result shows that using this algorithm, the height measurement error of sand pipes can be basically controlled within ± 1 mm, with an average measurement accuracy of 98.74%, indicating that the algorithm has a certain degree of robustness.

Inspection of pantograph state of EMU is one of the basic tasks of vehicle daily maintenance. There are three common inspection methods, including manual visual inspection, fixed-point image detection and on-board image detection. Due to the small number of pantograph fault samples that can be obtained, the present pantograph anomaly identification algorithms based on deep learning perform poorly. Therefore, this paper proposes an on-line recognition method based on feature analysis and independent of the number of fault samples. Visual features of the visible light images of pantograph which collected in real time through 3C device of EMU are used to identify abnormal states of pantograph. Firstly, the light intensity of the operating environment is judged by the image gray feature, and the region of interest (ROI) of the pantograph is segmented by the tracking matching algorithm. Then, the object features in the ROI of each frame such as threshold, contour thickness and tilt angle are extracted to detect abnormal states respectively, including sheep angle missing, front carbon sliding plate defect and bow head tilt, etc. Finally, the characteristic rules of pantograph anomaly determination are designed to realize the identification of abnormal state of pantograph. Test results show that the method and system proposed in this paper can detect abnormal states of the pantograph, such as missing horns, front carbon sliding blocks and bow head tilting, in both day and night environments. The average detection rate of defects is greater than 98%, which shows the method has great stability and practicability.

Aiming at the problem of insufficient detection frame size accuracy in the deep learning based wheelset tread defect detection algorithm, this paper proposes a tread defect detection algorithm based on YOLOv3-tiny and traditional image algorithm, which can realize fast positioning of defects with low CPU consumption and precise measurement of geometric parameters. First, image enhancement is performed on the small samples obtained in the industrial scene, and then the YOLOv3-tiny algorithm is used to perform migration learning on tread defects to achieve rough localization of defects. In order to solve the key problems that the detection frame is too large and too small, traditional image algorithms such as Fourier transform, band-stop filter, and threshold segmentation are used to construct a defect size measurement model, contours of roughly located defects are extracted and detection frame size is optimized, and finally location and size of defect are accurately calculated. Defect location experimental results show that the average accuracy of defect identification is 89.4% and the CPU consumption does not exceed 10% when IoU threshold is 0.5. Experimental results of defect measurement show that the algorithm can optimize 74 out of 90 inspection frames and obtain a more accurate defect size. The above experimental results show that the detection algorithm in this paper is effective in improving size accuracy of detection frame.

Periodic detection of wheel tread is necessary for train operation safety. Reference positioning of inner side benchmark is a traditional method for tread detection but there are problems of positioning error caused by field factors in wheel tread dynamic detection such as reference tilt by hunting, foreign matter and light interference. A reference positioning method for wheel tread dynamic detection is proposed in this paper. After extracting the point cloud data through structured light calibration, center-line extraction and other algorithms, reference feature points of the inner side are segmented combined with tread features, and an iterative re-weighted least squares line fitting (IRLS-LF) method is used to realize robust positioning of the inner side benchmark. Under the dynamic tilt condition, the experimental man-machine comparison deviations of flange height and thickness based on IRLS-LF positioning results are ±0.1mm and ±0.2mm respectively, and the both deviation range widths based on LSLF positioning results and fixed-parameter algorithm positioning results are about 0.8 mm. Experimental results show that this method can effectively solve the datum positioning deviation caused by field factors, and effectively ensure the measurement accuracy and robustness of wheel tread dynamic detection.

The environment of operation and maintenance of locomotives and rolling stocks is complex. Factors such as dust and reflection make point cloud missing, noise and false points, which seriously affect the accuracy of locomotive robot brake shoe image detection. To this end, this paper presents an size measurement algorithm of locomotive brake shoe for locomotive robot based on 3D image. Firstly, it realizes automatic transformation between the template region of interest (ROI) and measurement ROI according to the camera perspective transformation and point cloud registration algorithm, which makes up for the repeated positioning error of the locomotive robot to a certain extent. For the problem of point cloud missing and noise caused by reflection, RANSAC algorithm is used to fit the reference ROI in plane to make up for the loss of precision. The algorithm of automatic filtering of ordered point cloud is used to filter the point cloud between brake disc and brake shoe effectively. For the difficulty of edge discrimination by the false point cloud caused by lock brake and specular reflection of brake disc surface, this paper designs a filtering operator to preliminarily separate the edge of brake shoe and extract the ROI on the side of the brake shoe. Then, according to the imaging characteristics of the brake shoe, the gradient-based edge extraction and tracking algorithm is used to realize the accurate extraction of point cloud boundary of brake shoe and the accurate measurement of brake release gap. Finally, the accurate dimension measurement is realized by using the statistical method of sorting strategy. By the algorithm presented in this paper, accurate measurement can be realized under the condition that slack gap is less than 2mm. The method is used to measure the brake shoe in different shape, position and lighting complex environment, and the Vernier Caliper is used to measure it. The results show that the measuring accuracy of brake shoe wear size is within ±1mm range, and the algorithm has certain robustness.

Single cell sequencing (SCS) is a technique for precise analysis of cells at an individual level, which provides a new perspective on the identification of individual cell types, functions, states and interactions with other cells, and greatly deepens the understanding of cellular heterogeneity and genetic and molecular functional diversity. With the continuous optimization of various technical aspects, SCS technology has been widely used in many research areas, and the study of the hematopoietic system is an example of its application. SCS has not only assisted in the construction of relevant hematopoietic cell profiles under physiological and pathophysiological conditions in basic research, but also explored possible pathways of hematopoietic cell development and differentiation in clinical practice. Moreover, in the process of clinical diagnosis and treatment, it can effectively promote the deciphering of mechanisms of disease occurrence, progression and prognosis, and facilitate the exploration of potential factors of phenomena such as significant differences in individual outcomes and ease of relapse. Therefore, this paper reviews the technical overview and development trend of SCS and its application in the hematopoietic system, with a view to providing references for subsequent positive and reasonable application of SCS.

Slider is one of the main parts of a rocket projectile,which determines the stability and safety of a rocket launch. A slider structure design that satisfies the suspended-type launch was introduced in this research. Based on the theoretical analysis of offtrack speed and time,the slider structure was designed. By using numerical simulations,the strength of front slider under two different situations,ontrack and offtrack,was checked. The results show that the strength of slider meets the design requirement. The designed slider was applied to a rocket projectile flying test and the design feasibility was verified.

As the national policy encourage to reduce the fuel consumption and oil prices rising gradually,to reduce fuel consumption of the vehicle is widely concerned.The fuel consumption is closely related to the transmission efficiency,and the rear axle plays an important role in auto transmission system and different lubricant has a great influence on the transmission efficiency of rear axle,the viscosity of the lubricant,the losses of gear meshing and churning losses are analyzed,a lot of experiments are conducted to investigate the influence of viscosity of lubricant on transmission efficiency of rear axle.It is found that relatively low viscosity lubricant contributes to improving the transmission efficiency of rear axle and makes an important significance on reducing vehicle fuel consumption.

With the target of reducing the friction torque of tapered roller bearing,the globally optimal solution of bearing inner structural parameters is obtained by using the genetic algorithm.The friction torque,gearbox transmission efficiency,and vehicle fuel consumption and sliding distance are tested before and after the bearings are optimized.The results show that,the bearing friction torque is reduced,the gearbox transmission efficiency is increased,and the vehicle fuel consumption is slightly decreased while the vehicle sliding distance is highly improved.

The aspect ratio of sheet material is an important characteristic parameter. In this study, the mica sheet was used as the research object, and polystyrene sphere was introduced as the fulcrum material. The shape of polystyrene sphere was obviously different from the mica sheet. The experimental results reveal that when the mass ratio of mica sheet to polystyrene sphere is 1 : 3, the number of mica sheet in vertical orientation reaches the maximum. The length and thickness of 200 mica sheets were randomly collected, and its statistical average value of aspect ratio is 15. 37. The fulcrum material brings a huge number of fulcra, which significantly increases the probability of vertical mica sheet. This method can quickly and intuitively measure the length and thickness of mica sheets at the same time, and effectively improve the efficiency and accuracy of the aspect ratio of mica sheets. [ABSTRACT FROM AUTHOR]

Near zero expansion oxide functional ceramics Zr0.5Hf0.5V1.4P0.6O7 was synthesized by the traditional solid-state method and then the thermal expansion properties of the synthesized samples were explored. X-ray diffraction(XRD), Raman spectra and thermal dilatometry were used to investigate the coefficient of thermal expansion (CTE), isotropy and phase transition of Zr0.5Hf0.5V1.4P0.6O7.Hf4+/P5+ double ion doping results in the material has smaller coefficient of thermal expansion. The investigation results show that the samples are single cubic phase with the space group of Pa3 in the crystal structure. The linear expansion coefficient of Zr0.5Hf0.5V1.4P0.6O7 is calculated to be - 1. 56 x 10-6 K-1 in the temperature range from 334 K to 673 K and has near-zero thermal expansion characteristic in a wide temperature range. Due to the influence of the internal microstructure of the solid solution, there is a certain gap between the expansion test results and the X-ray diffraction results at variable temperature. The near zero thermal expansion (NZTE) property of Zr0.5Hf0.5V1.4P0.6O7 provides a basis for the synthesis of materials with controllable expansion coefficient of negative thermal expansion materials. [ABSTRACT FROM AUTHOR]

Near zero expansion oxide functional ceramics Zr0.5Hf0.5V1.4P0.6O7 was synthesized by the traditional solid-state method and then the thermal expansion properties of the synthesized samples were explored. X-ray diffraction(XRD), Raman spectra and thermal dilatometry were used to investigate the coefficient of thermal expansion (CTE), isotropy and phase transition of Zr0.5Hf0.5V1.4P0.6O7.Hf4+/P5+ double ion doping results in the material has smaller coefficient of thermal expansion. The investigation results show that the samples are single cubic phase with the space group of Pa3 in the crystal structure. The linear expansion coefficient of Zr0.5Hf0.5V1.4P0.6O7 is calculated to be - 1. 56 x 10-6 K-1 in the temperature range from 334 K to 673 K and has near-zero thermal expansion characteristic in a wide temperature range. Due to the influence of the internal microstructure of the solid solution, there is a certain gap between the expansion test results and the X-ray diffraction results at variable temperature. The near zero thermal expansion (NZTE) property of Zr0.5Hf0.5V1.4P0.6O7 provides a basis for the synthesis of materials with controllable expansion coefficient of negative thermal expansion materials. [ABSTRACT FROM AUTHOR]

Green pellet pressing is critical step in the preparation of oxide ceramic fuel that decides density, strength and microstructure of green pellets and pellets. The medium mode floating pressing properties of calcined alumina and Comeo alumina powder were compared, and the causes and solving measures of green pellets appearance defects were studied. The results show that the density of calcined alumina compact is much higher than that of Comeo alumina compact, but the strength of calcined alumina compact is much lower than that of Comeo alumina compact. The formability and compressibility of Comeo alumina and calcined alumina are opposite. With the increase of pressing pressure, the density and strength of Comeo alumina green pellets and calcined alumina green pellets gradually increase, but the influence of the properties of pressing powder on the density and strength is greater than the pressing parameters. The pressing curves of Comeo alumina green pellets and calcined alumina green pellets accord well with Huang Peiyun's double logarithm equation. Alumina is an inelastic compression in the pressing process, and there are work hardening and friction in the medium die. The density and strength of green pellets are related to powder strength, powder morphology and pressing pressure, but have nothing to do with pressing time, reducing time and demoulding pressure. With the increase of pressing pressure, the number of capping, blasting and crushing of calcined alumina green pellets decreases, and with the increase of demoulding maintenance pressure, the number of lid, blasting and crushing increases, and the degree of crushing deepens. Increasing the pressing pressure and decreasing the demoulding maintenance pressure are beneficial to reduce the defects such as lid dropping, head blasting and crushing, and when the pressure is 160 kN, macroscopic cracks appear on the surface of the green pellets. The low addition of zinc stearate makes the friction phenomenon of the medium die serious, resulting in side scratches and cracks. Zinc stearate plays the role of lubrication of the inner wall of the middle mold in the pressing stage. The sintering experiments show that the density of the pellet decreases gradually with the increase of zinc stearate addition, and the porosity of the pellet increases obviously. Zinc stearate acts as a pore-forming agent in the sintering stage. So when adding zinc stearatethe role of lubrication and pore-making should be considered at the same time.

Objective: To explore the clinical manifestations and genetic basis for a rare case of Generalized arterial calcification of infancy (GACI)., Methods: A 44-day-old female infant who was treated at Baoding Hospital of Beijing Children's Hospital Affiliated to Capital Medical University on August 26, 2022 was selected as the study subject. Clinical data of the child was collected, and Trio-whole exome sequencing (Trio-WES), whole genome copy number variation sequencing (CNV-seq) and minigene splicing assay were carried out to analyze the pathogenicity of the variants., Results: The child had presented with fever and high inflammatory indicators, for which treatment with various antibiotics was ineffective. Ultrasound had revealed extensive arterial calcification and arterial wall thickening. The child was suspected for GACI with arteritis related to the primary disease. Her fever was relieved by treatment with glucocorticoid and biological agents. Trio-WES revealed that she has harbored compound heterozygous variants of the ABCC6 gene, namely c.4404-1G>A and c.4041+5G>T, for which the latter was unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics, the variants were classified as likely pathogenic (PVS1+PM2_Supporting) and variant of unknown significance (PM2_Supporting+PM3+PP3), respectively. The result of CNV-seq was negative. And the minigene splicing assay has further verified that both variants can result in alternative splicing., Conclusion: For pyrexia with unknown causes and refractory to conventional treatment, it is necessary to recommend early genetic testing to avoid missed diagnosis of GACI.

Background: Acute cerebral infarction is a form of Trousseau syndrome (TS), but is relatively rare and often overlooked by clinicians. The aim of this study was to investigate the clinical, laboratory and imaging features of acute cerebral infarction in non-small cell lung cancer (NSCLC) patients with TS., Methods: Clinical data, laboratory examination and imaging data of 25 NSCLC patients with TS presented with acute cerebral infarction were collected retrospectively for analysis., Results: Of the 25 patients, 18 males and 7 females, aged 39-78 years old, including 22 cases of adenocarcinoma, 2 cases of squamous cell carcinoma, and 1 case of large cell carcinoma; all patients had clinical symptoms and signs of acute cerebral infarction; plasma D-dimer was significantly increased, and prothrombin time and activated partial thromboplastin time were shortened to varying degrees; all patients showed acute multiple cerebral infarction foci involving multiple intracranial arterial blood supply areas on plain head magnetic resonance imaging (MRI) [diffusion-weighted imaging (DWI) sequence], the blood supply vessel lumen corresponding to the infarction foci did not show moderate to severe stenosis on the head MR angiography (MRA)., Conclusions: NSCLC with multiple acute cerebral infarctions is a rare manifestation of TS, which is characterized by multiple acute cerebral infarctions involving multiple arterial blood supply areas with significant hypercoagulability. Improving the early understanding of this disease can provide some help for clinical diagnosis and treatment.

Objective: To explore the clinical manifestations and laboratory examination characteristics of neonatal dengue fever., Method: A retrospective analysis of 12 cases of neonatal dengue fever treated in the Guangdong Women and Children's Hospital and Guangzhou Women and Children's Medical Center was conducted, and related literature was reviewed., Result: Twelve cases of neonatal dengue fever included 9 males and 3 females; their age was 30 min after birth to 29 d, the age of onset was 30 min-24 d. (1) CLINICAL FEATURES: fever was present in 11 cases, rash in 6 cases, bleeding in 1 case, jaundice in 5 cases, cough in 1 case, coagulopathy in 2 cases. (2) Mothers' perinatal conditions: 7 mothers were confirmed to have dengue fever, 2 mothers had suspected dengue fever, and in 3 mothers the dengue fever was excluded. Eight mothers prenatally had fever. (3) LABORATORY TESTS: Thrombocytopenia was found in 11 cases (19×10(9)-156×10(9)/L), activated partial thromboplastin time prolonged in 11 cases (44.0-89.8 s), fibrinogen decreased in 5 cases (1.17-3.02 g/L), aspartate aminotransferase (AST) increased in 5 cases (28-78 U/L), creatine kinase (CK-MB) increased in 4 cases (13-86 U/L), hypokalemia in 1 case (2.8-5.1 mmol/L ), C- reactive protein (CRP) increased in 6 cases (0.04-46.05 mg/L). (4) Treatment and prognosis: platelet transfusion was used in 2 cases, anti-infective therapy was given to 6 cases, intravenous gamma globulin treatment was used in 5 cases, hospitalization was 4-17 d, 10 cases were cured, 2 cases were discharged after condition was improved. Literature search was performed with "neonatal dengue" as keywords at Wanfang, Weipu, and CNKI, no relevant reports were found. Pubmed search was done with "neonatal dengue" and "case report" as keywords, 15 reports were retrieved during 1990 and 2014, which reported 30 cases, all acquired the disease via vertical transmission; the main clinical manifestations were fever, rash, petechiae, anemia, jaundice, tachycardia, and hepatomegaly; laboratory test: all had visible purpura due to thrombocytopenia; anti-infective treatment, platelet transfusion and symptomatic treatment were given, and all the 30 cases of infants were cured., Conclusion: The clinical manifestations of neonatal dengue fever are characterized by fever and the disorder of blood coagulation system. The course of disease is mild, lack of specific clinical symptoms, and the prognosis is good. Mother to infant vertical transmission of dengue virus is one of the ways of transmission.

Objective: In order to study the role of SS2 Type IV Secretion System VirD4 in evasion of the host innate immune killing, we constructed a knockout mutant AVirD4. Then we studied its biological activity and virulence., Methods: The two VirD4 flanking DNA sequences were amplified using genome of 05ZYH33 as template. We also amplified the Cm sequence of shuttle vector pSET1, and through overlap extension PCR we connected the three fragments together. Using suicide vector pSET4s, we constructed the recombinant gene knockout vector pSET4s::VirD4. The mutant AVirD4 was successfully constructed by allelic replacement. Virulence of mutant strain was compared with wild type strain 05ZYH33 through in vitro bactericidal assays, competitive infection and challenge experiment of CD1 mice., Results: Mutant strain AVirD4 was constructed successfully, its virulence attenuated compared to the wild type strain., Conclusion: These findings indicated that Type IV Secretion System component VirD4 contributed to the virulence of S. suis with important functions in evading innate immunocyte killing.

Objective: To study the effect of the volatile oil from nutmeg on liver microsomal cytochrome P450 in mice., Method: Mice were administered the volatile oil from nutmeg at 0.4, 0.8 and 1.2 mg x g(-1), respectively, twice a day for 10 days. And then, the contents of liver microsomal cytochrome P450 (CYP), cytochrome b5 (Cytb5), MDA and GST in serum were examined by UV chromatography method., Result: The contents of liver CYP, Cytb5 and GST in serum were increased significantly (P < 0.01) and the contents of MDA was reduced significantly (P < 0.01)., Conclusion: The volatile oil from nutmeg showed induction effect on the hepatic microsomal CYP in mice.

DNA fragment containing human alpha-defensin 5 mature peptide (mHD-5) coding sequence with biased codons of E. coli was amplified by PCR, which was subsequently cloned into the plasmid pMAL-p2x in order to create pMAL-p2x-mHD-5 expression vector. The plasmid pMAL-p2x-mHD-5 was transferred into engineered strain BL21(DE3) to express heterogeneous fusion protein (MBP-mHD-5). The soluble MBP-mHD-5 targeted protein inducible expressed by IPTG was accounted for about 30% under optimized conditions. The recombinant mHD-5 (rmHD-5) peptide was successfully purified through a separation process including affinity chromatography, Factor Xa digestion and ion exchange chromatography. The bioactivity of rmHD-5 was examined by bacteria-inhibition tests in liquid culture. The growth of E. coli ATCC25922 was dramatically suppressed with an inhibition rate of 90%, with the presence of 62.5 microg/mL rmHD-5 in the media. These results indicate that the strategy of soluble expression of fusion protein in E. coli can be a useful and practical way to produce bioactive defensins.