Condition monitoring of axial piston pump

Condition Monitoring is an area that has seen substantial growth in the last few decades. The purpose for implementing condition monitoring in industry is to increase productivity, decrease maintenance costs and increase safety. Therefore, condition monitoring can be used not only for planning maintenance but also for allowing the selection of the most efficient equipment to minimize operating costs. Hydraulic systems are widely used in industry, aerospace and agriculture and are becoming more complex in construction and in function. Reliability of the systems must be supported by an efficient maintenance scheme. Due to component wear or failure, some system parameters may change causing abnormal behaviour in each component or in the overall circuit. Research in this area has been substantial, and includes specialized studies on artificial fault simulation at the University of Saskatchewan. In this research, an axial pump was the focus of the study. In an axial piston pump, wear between the various faces of components can occur in many parts of the unit. As a consequence, leakage can occur in locations such as between the valve plate and barrel, the drive shaft and oil wiper, the control piston and piston guide, and the swash plate and slippers. In this study, wear (and hence leakage) between the pistons and cylinder bores in the barrel was of interest. Researchers at the University of Saskatchewan, as well as at other research institutions, have been involved in studies to detect wear in pumps using a variety of condition monitoring algorithms. However, to verify the reliability and indeed, limitations of some of the approaches, it is necessary to test the algorithms on systems with “real” leakage. To introduce actual wear in the piston of pumps can be very difficult and very expensive. Hence, introducing piston wear in an “artificial” manner would be of great benefit in the evaluation of various condition monitoring techniques.Since leakage is a direct consequence of piston wear, it is logical to conclude that varying the leakage in some prescribed manner can be used to artificially simulate wear. A prime concern, therefore, is to be able to precisely understand the dynamic relationships between the wear and leakage and the effect it has on the output flow or pressure waveform from the pump.Introducing an artificial leakage to simulate the wear of pistons is a complex task. The creation of an artificial leakage path was not simply a process of providing a resistive short to the tank at the outlet of the pump port as was done in other studies. The objective was to create a leakage environment that would simulate leakage from a single piston (or combination of several pistons thereof). The complexity of the flow and pressure ripple waveforms (which various condition monitoring algorithms did require) was such that a more comprehensive leakage behaviour had to be modeled and experimentally created. A pressure control servo valve with a very high frequency response was employed to divert the flow from the pump outlet with a prescribed waveform directly to the tank to simulate the piston leakage from the high pressure discharge chamber to the pump case drain chamber as the simulated worn piston made contact with the high pressure chamber. The control algorithm could mimic the action of a single worn piston at various degrees of wear. The experimental results indicated that the experimental system could successfully introduce artificial leakage into the pump which was quite consistent with a unit with a “real” worn piston. Comparisons of the pressure ripples from an actual faulty pump (worn piston) and the “artificial” faulty pump (artificial leakage) are presented

Modeling Arctic Intermediate Water: The effects of Neptune parameterization and horizontal resolution

Arctic Intermediate Water (AIW), advected from the North Atlantic Ocean, has a potential influence on climate in the Arctic region, but is poorly simulated in coarse resolution models. In this study, a coupled ice-ocean model is used to investigate features of AIW by conducting two sensitivity experiments based on Neptune parameterization and horizontal resolution. The results show that both experiments improve the modeling of temperature profiles in the western Eurasian Basin, mainly as a result of more realistic volume and heat transport through the Fram Strait. Topographical flows are well reproduced using Neptune parameterization or a finer horizontal resolution. In the eddy-permitting model with relatively higher resolution, the velocity field is more realistic than in the Neptune parameterization model, and complex inflow and outflow belts of barotropic structure are well reproduced. The findings of this study suggest that increased model resolution, as provided by an eddy-resolving model, is needed to reproduce realistic circulation and thermohaline structure in the Arctic, since the Rossby radius of deformation is only several kilometers in the Arctic Ocean. This paper focuses on the external heat input rather than internal mixing process, and obtains a conclusion that the heat input from the Fram Strait is a main factor to reproduce AIW in the Eurasian Basin successfully, at least for the western part

Acoustic Vortex in Waveguide with Chiral Gradient Sawtooth Metasurface

The acoustic vortex states with spiral phase dislocation that can carry orbital angular moment (OAM) have aroused many research interests in recent years. The mainstream methods of generating acoustic vortex are based on Huygens-Fresnel principle to modulate the wavefront to create spatial spiral phase dislocation. In this work, we propose an entirely new scenario to generate acoustic vortex in a waveguide with chiral gradient sawtooth metasurface. The physical mechanism of our method is to lift the degenerate dipole eigenmodes through the scattering effect of the chiral surface structure, and then the superposition of them will generate both and order vortices in place. Compared to the existing methods of acoustic vortex production, our design has many merits, such as easy to manufacture and control, the working frequency is broadband, sign of vortex order can be readily flipped. Both the full-wave simulations and experimental measurements validate the existence of the acoustic vortices. The torque effect of the acoustic vortices is also successfully performed by rotating a foam disk as a practical application. Our work opens up a new route for generating acoustic vortex and could have potential significances in microfluidics, acoustic tweezers and ultrasonic communication, etc

Effect of Co-fermentation with Monascus and Aspergillus oryzae on Flavor Substances and Microfloral Structure of Soybean Paste

In order to explore the effect of co-fermentation with Monascus and Aspergillus oryzae on the quality of soybean paste, the volatile flavor components in soybean pastes produced using pure and mixed cultures of A. oryzae (Piniang M003) and Monascus (PM001) were determined by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and comparatively analyzed by principal component analysis (PCA), and Illumina MiSeq sequencing technology was used to analyze the changes in the microbial community structure during the mixed culture fermentation process. Meanwhile, the correlation between the major microorganisms and the major flavor substances was analyzed. The results showed that the composition and content of flavor substances and the composition and relative abundance of microbial communities in the soybean paste produced by co-fermentation were significantly better than those in the soybean paste fermented with A. oryzae monoculture. The major flavor substances in soybean paste were significantly positively correlated with dominant genera such as Aspergillus, Bacillus, Monascus and Leuconostoc. The flavor quality of the soybean paste produced with a mixed culture of A. oryzae and Monascus in a ratio of 3:1 (m/m) was best. The results of the study showed that the mixed culture fermentation with Monascus and A. oryzae could significantly improve the flavor quality of soybean paste, which will be informative for the improvement of the flavor quality of soybean paste

Magnetic-field-induced electronic instability of Weyl-like fermions in compressed black phosphorus

Revealing the role of Coulomb interaction in topological semimetals with Dirac/Weyl-like band dispersion shapes a new frontier in condensed matter physics. Topological node-line semimetals (TNLSMs), anticipated as a fertile ground for exploring electronic correlation effects due to the anisotropy associated with their node-line structure, have recently attracted considerable attention. In this study, we report an experimental observation for correlation effects in TNLSMs realized by black phosphorus (BP) under hydrostatic pressure. By performing a combination of nuclear magnetic resonance measurements and band calculations on compressed BP, a magnetic-field-induced electronic instability of Weyl-like fermions is identified under an external magnetic field parallel to the so-called nodal ring in the reciprocal space. Anomalous spin fluctuations serving as the fingerprint of electronic instability are observed at low temperatures, and they are observed to maximize at approximately 1.0 GPa. This study presents compressed BP as a realistic material platform for exploring the rich physics in strongly coupled Weyl-like fermions.Comment: 10 pages, 4 figure

Effect of Different Cultivars of Broad Bean on the Quality of Pixian Broad Bean Chili Paste

To elucidate the influence of various broad bean raw materials on the quality of Pixian broad bean chili paste (PBCP), an investigation was undertaken utilizing five distinct cultivars of broad beans to prepare PBCP and physicochemical indices, free amino acids and volatile profiles were analyzed. The results revealed notable disparities (P1, a total of 11 key flavor substances were screened, with most of these substances being relatively abundant in PBCPs fermented by CH23 and YD. Overall, qualities of PBCPs fermented by CH18, CH23, and TCX were better than that fermented by SCZG and YD. However, defect was observed in the physical appearance of PBCP fermented by TCX. Consequently, CH18 and CH23 were more appropriate for the processing of PBCP. This research underscores the significance of broad bean cultivar as an instrumental factor driving the variances in physicochemical and sensory attributes of PBCP, and it thereby advocates the selection of raw material to improve the quality of final products

Metformin Uniquely Prevents Thrombosis by Inhibiting Platelet Activation and mtDNA Release

Thrombosis and its complications are the leading cause of death in patients with diabetes. Metformin, a first-line therapy for type 2 diabetes, is the only drug demonstrated to reduce cardiovascular complications in diabetic patients. However, whether metformin can effectively prevent thrombosis and its potential mechanism of action is unknown. Here we show, metformin prevents both venous and arterial thrombosis with no significant prolonged bleeding time by inhibiting platelet activation and extracellular mitochondrial DNA (mtDNA) release. Specifically, metformin inhibits mitochondrial complex I and thereby protects mitochondrial function, reduces activated platelet-induced mitochondrial hyperpolarization, reactive oxygen species overload and associated membrane damage. In mitochondrial function assays designed to detect amounts of extracellular mtDNA, we found that metformin prevents mtDNA release. This study also demonstrated that mtDNA induces platelet activation through a DC-SIGN dependent pathway. Metformin exemplifies a promising new class of antiplatelet agents that are highly effective at inhibiting platelet activation by decreasing the release of free mtDNA, which induces platelet activation in a DC-SIGN-dependent manner. This study has established a novel therapeutic strategy and molecular target for thrombotic diseases, especially for thrombotic complications of diabetes mellitus

Immunization of Mice with Recombinant Protein CobB or AsnC Confers Protection against Brucella abortus Infection

Due to drawbacks of live attenuated vaccines, much more attention has been focused on screening of Brucella protective antigens as subunit vaccine candidates. Brucella is a facultative intracellular bacterium and cell mediated immunity plays essential roles for protection against Brucella infection. Identification of Brucella antigens that present T-cell epitopes to the host could enable development of such vaccines. In this study, 45 proven or putative pathogenesis-associated factors of Brucella were selected according to currently available data. After expressed and purified, 35 proteins were qualified for analysis of their abilities to stimulate T-cell responses in vitro. Then, an in vitro gamma interferon (IFN-γ) assay was used to identify potential T-cell antigens from B. abortus. In total, 7 individual proteins that stimulated strong IFN-γ responses in splenocytes from mice immunized with B. abortus live vaccine S19 were identified. The protective efficiencies of these 7 recombinant proteins were further evaluated. Mice given BAB1_1316 (CobB) or BAB1_1688 (AsnC) plus adjuvant could provide protection against virulent B. abortus infection, similarly with the known protective antigen Cu-Zn SOD and the license vaccine S19. In addition, CobB and AsnC could induce strong antibodies responses in BALB/c mice. Altogether, the present study showed that CobB or AsnC protein could be useful antigen candidates for the development of subunit vaccines against brucellosis with adequate immunogenicity and protection efficacy

Xanthohumol alleviates oxidative stress and impaired autophagy in experimental severe acute pancreatitis through inhibition of AKT/mTOR

Severe acute pancreatitis (SAP) is a lethal gastrointestinal disorder, yet no specific and effective treatment is available. Its pathogenesis involves inflammatory cascade, oxidative stress, and autophagy dysfunction. Xanthohumol (Xn) displays various medicinal properties,including anti-inflammation, antioxidative, and enhancing autophagic flux. However, it is unclear whether Xn inhibits SAP. This study investigated the efficacy of Xn on sodium taurocholate (NaT)-induced SAP (NaT-SAP) in vitro and in vivo. First, Xn attenuated biochemical and histopathological responses in NaT-SAP mice. And Xn reduced NaT-induced necrosis, inflammation, oxidative stress, and autophagy impairment. The mTOR activator MHY1485 and the AKT activator SC79 partly reversed the treatment effect of Xn. Overall, this is an innovative study to identify that Xn improved pancreatic injury by enhancing autophagic flux via inhibition of AKT/mTOR. Xn is expected to become a novel SAP therapeutic agent

Highly potent multivalent VHH antibodies against Chikungunya isolated from an alpaca naïve phage display library

Background Chikungunya virus (CHIKV) is a re-emerged mosquito-borne alphavirus that can cause musculoskeletal diseases, imposing a substantial threat to public health globally. High-affinity antibodies are need for diagnosis and treatment of CHIKV infections. As a potential diagnostic and therapeutic agent, the multivalent VHH antibodies is a promising tookit in nanomedicine. Here, we developed potent multivalent VHH antibodies from an alpaca naïve phage display library targeting the E2 glycoprotein of the CHIKV virus. Results In the present study, we generated 20 VHH antibodies using a naïve phage display library for binders to the CHIKV E2 glycoprotein. Of these, multivalent VHH antibodies Nb-2E8 and Nb-3C5 had specific high-affinity binding to E2 protein within the nanomolar range. The equilibrium dissociation constant (KD) was between 2.59–20.7 nM, which was 100-fold stronger than the monovalent antibodies’ affinity. Moreover, epitope mapping showed that Nb-2E8 and Nb-3C5 recognized different linear epitopes located on the E2 glycoprotein domain C and A, respectively. A facile protocol of sandwich ELISA was established using BiNb-2E8 as a capture antibody and HRP-conjugated BiNb-3C5 as a detection antibody. A good linear correlation was achieved between the OD450 value and the E2 protein concentration in the 5–1000 ng/mL range (r = 0.9864, P < 0.0001), indicating its potential for quantitative detection of the E2 protein. Conclusions Compared to monovalent antibodies, multivalent VHH antibodies Nb-2E8 and Nb-3C5 showed high affinity and are potential candidates for diagnostic applications to better detect CHIKV virions in sera. Graphical Abstrac