Remaining useful life prognostics for the electro-hydraulic actuator using relevance vector machine and optimized on-line incremental learning

The electro-hydraulic actuator plays a significant role in the automatic flight control system, so it is vital to predict the remaining useful life (RUL) for the electro-hydraulic actuators. Relevance vector machine (RVM) is flourishing in the field of RUL prognostics and gradually applied to the prediction of complex systems or components, but the general RVM cannot achieve on-line prediction efficiently due to its high computational complexity, besides, the sparse RVM model which is only based on historical data set could cause a large prediction error in the long term. To deal with these plights, an optimized incremental learning algorithm based on RVM is presented taking full advantage of the on-line updating samples to improve the precision of prognostics

Cellular automaton modeling of semisolid microstructure formation

Computer modeling of semi-solid structure formation is of significance in both understanding the mechanisms of globular structure formation and determining the effect of solidification conditions on final microstructure. A modified cellular automaton (mCA) model has been developed, which is coupled with macroscopic models for heat transfer calculation and microscopic models for nucleation and grain growth. The mCA model is applied to A356 Al alloy – one of the most widely used semi-solid alloys, to predict grain morphology and grain size during semi-solid solidification, and determines the effects of pouring temperature on the final microstructure. The modeling results show that the lower the initial temperature, the finer grain size will be obtained. In addition, the model can be used to predict the solutal micro-segregation

Macerals of lignite and the effect of alkali treatment on the structure and combustion performance of lignite

Suppressing the spontaneous combustion of lignite is of great significance for safe transportation and efficient utilization of lignite. Taking the Shengli lignite as the research object, two different macerals, inertinite and huminite, were selected by optical microscope, and treated with NaOH respectively to study the relationship between the structure and combustion reaction performance of different macerals and lignite treated with NaOH. The structure of the prepared coal samples was characterized by SEM-EDS, XPS, FT-IR, XRD and Raman, and the changes of the main functional groups were analyzed. The effect of NaOH treatment on the combustion performance of different maceral lignite was investigated by TGA. The results showed that the ignition temperature of huminite lignite was about 10 ℃ earlier than that of inertinite, but the comprehensive combustion characteristic index of inertinite lignite was slightly higher than that of huminite. After the NaOH treatment, the lignite of different macerals showed a hysteresis of combustion, there were two obvious weight losses in the range of 200−500 ℃ and 650−800 ℃, respectively, and the mass loss was mainly concentrated in the second weight loss, in particular, the effect of huminite lignite was more significant, and the temperature corresponding to the maximum combustion reaction rate was about 60 ℃ behind that of inertinite. The kinetic analysis of the combustion process of the coal samples showed that the activation energy of combustion reaction of lignite with different macerals significantly increased after the NaOH treatment, and the huminite lignite was higher than that of inertinite lignite. The XPS/FT-IR results revealed that the contents of carboxylic oxygen-containing functional groups in different macerals of lignite treated by NaOH decreased, the main reason is that in the process of NaOH treatment, Na+ interacted with the carboxylic oxygen-containing functional groups in lignite to form the sodium carboxylate structure, and the relative amount of the sodium carboxylate structure in huminite coal was relatively large. It is believed that the inhibitory effect on the combustion of lignite with different macerals is attributed to the stability of the sodium carboxylate structure, and the number of the sodium carboxylate structure formed by combining with Na is the main reason for the difference in its combustion performance. The XRD/Raman analysis indicates that the formation of the sodium carboxylate structure in lignite leads to the increase of the order degree of carbon microcrystalline structure, and the order degree of huminite lignite is higher than that in inertinite

Characterization of a Novel Influenza Virus in Cattle and Swine: Proposal for a New Genus in the Orthomyxoviridae Family

We have recently reported the isolation of a novel virus, provisionally designated C/swine/Oklahoma/1334/2011 (C/OK), with 50% overall homology to human influenza C viruses (ICV), from a pig in Oklahoma. Deep RNA sequencing of C/OK virus found a matrix 1 (M1) protein expression strategy that differed from that of ICV. The novelty of C/OK virus prompted us to investigate whether C/OK virus could exist in a nonswine species. Significantly, we found that C/OK virus was widespread in U.S. bovine herds, as demonstrated by reverse transcription (RT)-PCR and serological assays. Genome sequencing of three bovine viruses isolated from two herds in different states further confirmed these findings. To determine whether swine/bovine C/OK viruses can undergo reassortment with human ICV, and to clarify the taxonomic status of C/OK, in vitro reassortment and serological typing by agar gel immunodiffusion (AGID) were conducted. In vitro reassortment using two human ICV and two swine and bovine C/OK viruses demonstrated that human ICV and C/OK viruses were unable to reassort and produce viable progeny. Antigenically, no cross-recognition of detergent split virions was observed in AGID between human and nonhuman viruses by using polyclonal antibodies that were reactive to cognate antigens. Taken together, these results demonstrate that C/OK virus is genetically and antigenically distinct from ICV. The classification of the new virus in a separate genus of the Orthomyxoviridae family is proposed. The finding of C/OK virus in swine and bovine indicates that this new virus may spread and establish infection in other mammals, including humans

Pediatric-inspired regimen for adolescent and adult patients with Philadelphia chromosome-negative acute lymphoblastic leukemia: a prospective study from China

Several international centers have used and reported pediatric-inspired regimens for adolescent and adult patients with Philadelphia chromosome-negative acute lymphoblastic leukemia (Ph- ALL). However, there is a lack of prospective data on the Chinese population. Herein, we performed a prospective study with a pediatric-inspired regimen (IH-2014 regimen) in treating adolescent and adult Ph- ALL patients in our center. From 2014 to 2021, a total of 415 patients aged between 14 and 65 years (median age, 27) were included in this study. After a median follow-up of 40.8 months, the 5-year overall survival, disease-free survival, and event-free survival rates were 53.8%, 51.1% and 45.0%, respectively. The regimen was generally well tolerated and safe, and the overall chemotherapy-related mortality was 3.6%. Age ≥ 40 years and persistent detectable minimal residual disease (MRD) post-induction were independent prognostic factors. Traditional risk factors for adult patients combined with MRD post-induction exhibit predictive significance for survival and relapse, which is helpful in the selection of subsequent treatment. Patients with high risk factors who can achieve deep MRD response after induction do not derive benefit from allogeneic hematopoietic stem cell transplantation

Differential tissue tropism and transmission efficiency of two dominant influenza D clades with overlapping but distinct receptor binding fine specificities in ferrets.

Influenza D virus (IDV) utilizes bovines as a primary reservoir causing periodical spillover to pigs and other hosts. In this study, we utilized ferrets to study IDV with a focus on the role of the Hemagglutinin-Esterase-Fusion (HEF) protein in the replication, tissue tropism, and transmission of two dominant clades of IDV- swine D/OK, and bovine D/660. In addition to swine D/OK, we rescued a chimeric virus (D/OK660HEF) expressing the bovine D/660 HEF using reverse genetic system. Two isogenic IDVs differing only in the HEF protein were characterized in ferrets with respect to viral shedding, tissue tropism, transmission, and pathogenesis. Ferrets intranasally infected with D/OK and D/OK660HEF showed similar levels of viral shedding but exhibited slight differences in transmission efficiency to contact sentinel ferrets. Specifically, D/OK replicated mostly in the upper respiratory tract and transmitted to 2/3 naive ferrets, while D/OK660HEF replicated in both upper and lower respiratory tract (trachea) but transmitted only to 1/3 naive ferrets. Both direct inoculated and contact sentinel ferrets seroconverted at 14 days post-infection, which indicated an association with viral replication fitness and transmission efficiency. Distinct receptor fine specificities plus six amino acid mutations in the receptor binding domain of the HEF protein between swine D/OK and bovine D/660 viruses may explain the different tissue tropism and transmission efficiency observed between these two viruses. Furthermore, while no detectable virus titers were observed in the lungs and intestines of ferrets, fluorescent RNAscope probe-based in-situ hybridization assay detected viral RNAs in these tissues. Finally, deep-sequencing revealed ferret-adapted mutations in PB1, PB2, and M segments that have not appeared in natural IDV isolates from bovines or pigs which need further characterization. Taken together, results of this study demonstrate that IDV is optimized for replication and spread in mammals and subtle mutations in HEF protein may affect viral tropism and transmission efficiency

A framework for modeling fault propagation paths in air turbine starter based on Bayesian network

Any minor fault may spread, accumulate and enlarge through the causal link of fault in a closed-loop complex system of civil aircraft, and eventually result in unplanned downtime. In this paper, the fault propagation path model (FPPM) is proposed for system-level decomposition and simplifying the process of fault propagation analysis by combining the improved ant colony optimization algorithm (I-ACO) with the Bayesian network (BN). In FPPM, the modeling of the fault propagation path consists of three models, namely shrinking model (SM), ant colony optimization model (ACOM), and assessment model (AM). Firstly, the state space is shrunk by the most weight supported tree algorithm (MWST) at the initial establishment stage of BN. Next, I-ACO is designed to improve the structure of BN in order to study the fault propagation path accurately. Finally, the experiment is conducted from two different perspectives for the rationality of the well-trained BN’s structure. An example of practical application for the propagation path model of typical faults on the A320 air turbine starter is given to verify the validity and feasibility of the proposed method. </jats:p

Remaining useful life prognostics for the rolling bearing based on a hybrid data-driven method

Rolling bearing is the core part of rotating mechanical equipment, so developing an effective remaining useful life prognostics method and alarming the impending fault for rolling bearing are of necessity to guarantee the reliable operation of mechanical equipment and schedule maintenance. The relevance vector machine is one of the substantially used methods for remaining useful life prognostics of rolling bearing. However, the accuracy generated by relevance vector machine drops rapidly in the long-term prognostics. To remedy this existing shortcoming of relevance vector machine, a novel hybrid method combining grey model, complete ensemble empirical mode decomposition and relevance vector machine are put forward. In the hybrid prognostics framework, the grey model is applied to gain a “raw” prediction result based on a trained model and produce an original error sequence. Subsequently, a new smoother error sequence reconstructed by complete ensemble empirical mode decomposition method is used to train relevance vector machine model, by which the future prediction error applied to correct the raw prediction results of grey model is projected. Ultimately, the online learning technique is used to implement dynamic updating of the “old” hybrid model, so that the remaining useful life of rolling bearing throughout the run-to-failure data set could be accurately predicted. The experimental results demonstrate the satisfactory prognostics performance. </jats:p