A new controller design of electro-hydraulic servo system based on empirical mode decomposition

The signal of electro-hydraulic servo system is non-stationary and time-varying due to the influence of vibration, noise and mechanical impact. The traditional digital filter always suffers delay in time domain and the delay increases along with the increasing of frequency. Considering the features of electro-hydraulic servo system, the Hilbert-Huang transform method is an effective method to decompose the original signal and obtain the noise components. Some improvements are made based on Hilbert Huang transform method and a new real time on-line filtering method is proposed in this paper. This improved filter is able to decompose out the noise components and other interference components from original signal, and remove them off in real time. Based on this new on-line filter, a new controller is also designed. Compared the filtering result with the traditional digital filter, this new controller’s control performance is much better

Theoretical model and characteristics analysis of deflector-jet servo valve’s pilot stage

To analyze the deflector-jet servo valve’s internal flow characteristics, a theoretical model of the complicated flow distribution in the deflector plate is established based on the offset jet attachment theory. When the deflector plate offsets, jet attachment parameters are attained to figure out the jet’s bending and colliding process. On this basis, an analytical method of acquiring the pilot valve’s pressure gain is derived. According to an actual pilot stage’s structure, pressure gain calculations are carried out. Meanwhile, the pilot valve’s mesh model is established for numerical simulation in order to examine the accuracy of the theoretical model. Calculation and numerical simulation show that the final oil jet is not sensitive to the deflector plate’s movement, which directly reveals the pressure stabilizing effect of the V-shaped structure on the deflector plate. Moreover, the experiment on the pressure gain is accomplished and experiment results verify the accuracy of the analytical calculation

Vector matching-based disturbance rejection method for load simulator

Position disturbance is the most troublesome problem for load simulator. It is difficult to work properly for a loading system, when the load-carrying object is moving. Therefore, it is of high significance to compensate for the position disturbance. To achieve this objective, a kind of vector matching-based disturbance rejection (VMBDR) method is proposed. If the input is periodic and the load simulator system satisfies linear superposition, a torque command can be constructed to eliminate the position disturbance of the load-carrying object, according to VMBDR. Fortunately, linear superposition of electric load simulator is verified by experiments, and most of the position disturbance is cyclical. Compared with other methods, the VMBDR does not depend on building a precise mathematical model. Therefore, it has better maneuverability and adaptability. Finally, experimental results show that VMBDR has effective disturbance rejection performance

A new controller design of electro-hydraulic servo system based on empirical mode decomposition

The signal of electro-hydraulic servo system is non-stationary and time-varying due to the influence of vibration, noise and mechanical impact. The traditional digital filter always suffers delay in time domain and the delay increases along with the increasing of frequency. Considering the features of electro-hydraulic servo system, the Hilbert-Huang transform method is an effective method to decompose the original signal and obtain the noise components. Some improvements are made based on Hilbert Huang transform method and a new real time on-line filtering method is proposed in this paper. This improved filter is able to decompose out the noise components and other interference components from original signal, and remove them off in real time. Based on this new on-line filter, a new controller is also designed. Compared the filtering result with the traditional digital filter, this new controller’s control performance is much better

Risk factors of CVD mortality among the elderly in Beijing, 1992 - 2009: An 18-year cohort study

Few researchers have examined the effects of multiple risk factors of cardiovascular disease (CVD) mortality simultaneously. This study was to determine the associations of combined lifestyle and other factors with CVD mortality among the elderly (n = 3,257), in Beijing, China, through data mining of the Beijing Longitudinal Study of Aging (BLSA). BLSA is a representative cohort study from 1992 to 2009, hosted by Xuan Wu Hospital. Competing risk survival analysis was conducted to explore the association between risk factors and CVD mortality. The factors focused mainly on lifestyle, physical condition, and the model was adjusted for age and gender. There were 273 of the 1,068 recorded deaths caused by CVD among the 2010 participants. Living in a suburban area (HR = 0.614, 95% CI: 0.410-0.921) was associated with lower CVD mortality. Increasing age (66-75: HR = 1.511, 95% CI: 1.111-2.055; ≥76: HR = 1.847, 95% CI: 1.256-2.717), high blood pressure (HR = 1.407, 95% CI: 1.031-1.920), frequent consumption of meat (HR = 1.559, 95% CI: 1.079-2.254) and physical inactivity (p = 0.046) were associated with higher CVD mortality. The study provides an instructional foundation for the control and prevention of CVD in Beijing, China

Characterization of monoclonal antibodies that specifically differentiate field isolates from vaccine strains of classical swine fever virus

Classical swine fever virus (CSFV) is a major animal pathogen threatening the global pork industry. To date, numerous anti-CSFV monoclonal antibodies (mAbs) and their recognizing epitopes have been reported. However, few mAbs were systematically characterized for the capacity to differentiate field CSFV isolates from CSF vaccine strains, and the molecular basis associated with antigenic differences between vaccines and field isolates is still largely unknown. In the present study, recombinant CSFV structural glycoproteins E2 of both virulent and vaccine strains and Erns of vaccine strain were expressed using eukaryotic cells and murine mAbs generated against E2 and Erns. After serial screening and cloning of the hybridomas, the viral spectra of mAbs were respectively determined by indirect fluorescent antibody assay (IFA) using 108 CSFVs, followed by Western blot analysis using expressed glycoproteins of all CSFV sub-genotypes including vaccine strains. The antigenic structures recognized by these mAbs were characterized by epitope mapping using truncated, chimeric, and site-directed mutated E2 and Erns proteins. We have identified two vaccine-specific, one field isolate-specific, and two universal CSFV-specific mAbs and five novel conformational epitopes with critical amino acid (aa) motifs that are associated with these five mAbs: 213EPD215, 271RXGP274, and 37LXLNDG42 on E2 and 38CKGVP42, W81, and D100/V107 on Erns. Particularly, E213 of E2 is field isolate-specific, while N40 of E2 and D100/V107 of Erns are vaccine strain-specific. Results from our study further indicate that N40D of E2 mutation in field strains was likely produced under positive selection associated with long-term mass vaccination, leading to CSFV evasion of host immune response. Taking together, this study provides new insights into the antigenic structure of CSFV E2 and Erns and the differentiating mAbs will contribute to the development of a diagnostic strategy to differentiate C-strain vaccination from natural infection (DIVA) of CSFV in terms of elimination of CSF in China

1H NMR-based metabolomics of paired tissue, serum and urine samples reveals an optimized panel of biofluids metabolic biomarkers for esophageal cancer

IntroductionThe goal of this study was to establish an optimized metabolic panel by combining serum and urine biomarkers that could reflect the malignancy of cancer tissues to improve the non-invasive diagnosis of esophageal squamous cell cancer (ESCC).MethodsUrine and serum specimens representing the healthy and ESCC individuals, together with the paralleled ESCC cancer tissues and corresponding distant non-cancerous tissues were investigated in this study using the high-resolution 600 MHz 1H-NMR technique.ResultsWe identified distinct 1H NMR-based serum and urine metabolic signatures respectively, which were linked to the metabolic profiles of esophageal-cancerous tissues. Creatine and glycine in both serum and urine were selected as the optimal biofluids biomarker panel for ESCC detection, as they were the overlapping discriminative metabolites across serum, urine and cancer tissues in ESCC patients. Also, the were the major metabolites involved in the perturbation of “glycine, serine, and threonine metabolism”, the significant pathway alteration associated with ESCC progression. Then a visual predictive nomogram was constructed by combining creatine and glycine in both serum and urine, which exhibited superior diagnostic efficiency (with an AUC of 0.930) than any diagnostic model constructed by a single urine or serum metabolic biomarkers.DiscussionOverall, this study highlighted that NMR-based biofluids metabolomics fingerprinting, as a non-invasive predictor, has the potential utility for ESCC detection. Further studies based on a lager number size and in combination with other omics or molecular biological approaches are needed to validate the metabolic pathway disturbances in ESCC patients

Studying the Inflammatory Responses to Amyloid Beta Oligomers in Brain-Specific Pericyte and Endothelial Co-Culture From Human Stem Cells

Background: Recently, the in vitro blood–brain barrier (BBB) models derived from human pluripotent stem cells have been given extensive attention in therapeutics due to the implications they have with the health of the central nervous system. It is essential to create an accurate BBB model in vitro in order to better understand the properties of the BBB, and how it can respond to inflammatory stimulation and be passed by targeted or non-targeted cell therapeutics, more specifically extracellular vesicles.Methods: Brain-specific pericytes (iPCs) were differentiated from iPSK3 cells using dual SMAD signaling inhibitors and Wnt activation plus fibroblast growth factor 2 (FGF-2). The derived cells were characterized by immunostaining, flow cytometry, and RT-PCR. In parallel, blood vessels organoids were derived using Wnt activation, BMP4, FGF2, VEGF, and SB431542. The organoids were replated and treated with retinoic acid to enhance the blood–brain barrier (BBB) features in the differentiated brain endothelial cells (iECs). Co-culture was performed for iPCs and iECs in the transwell system and 3D microfluidics channels.Results: The derived iPCs expressed common markers PDGFRb and NG2, and brain-specific genes FOXF2, ABCC9, KCNJ8, and ZIC1. The derived iECs expressed common endothelial cell markers CD31, VE-cadherin, and BBB-associated genes BRCP, GLUT-1, PGP, ABCC1, OCLN, and SLC2A1. The co-culture of the two cell types responded to the stimulation of amyloid β42 oligomers by the upregulation of the expression of TNFa, IL6, NFKB, Casp3, SOD2, and TP53. The co-culture also showed the property of trans-endothelial electrical resistance. The proof of concept vascularization strategy was demonstrated in a 3D microfluidics-based device.Conclusion: The derived iPCs and iECs have brain-specific properties, and the co-culture of iPCs and iECs provides an in vitro BBB model that show inflammatory response. This study has significance in establishing micro-physiological systems for neurological disease modeling and drug screening