Search

There is a need for an animal model that closely parallels human cochlea gestational development. This study aims to document porcine inner ear anatomy, and in vitro porcine derived inner ear cell culture characteristics. Twenty-four temporal bone were harvested from 12 adult pigs (Sus scrofa). Six were formalin fixed and their maximal diameters were measured. The cochlea duct length was determined by the insertion length of a Nucleus 22 cochlear implant in two bones. Four formalin fixed bones were sectioned for histology. Cochlear and vestibular tissues were harvested from non-fixed bones, cultured and characterized at different passages (P). Gene and protein expression of multipotent stem/progenitor (Nestin and Sox2), inner ear hair (Myosin VIIa, Prestin) and supporting (Cytokeratin 18 and Vimentin) cell markers were determined. The porcine cochlea was a 3.5 turn spiral. There was a separate vestibular compartment. The cochlear mean maximal diameter and height was 7.99 and 3.77 mm, respectively. Sphere forming cells were identified on phase-contrast microscopy. The relative mRNA expression levels of KRT18, MYO7A and SLC26A5 were significantly positively correlated in cochlear cultures; and MYO7A and SLC26A5; SOX2 and KRT18; NES and SLC26A5 genes were positively correlated in vestibular cultures (p = .037, Spearman correlation [τ] = .900). Inner ear sensory and stem cell characteristics persist in passaged porcine inner ear cells. Further work is required to establish the usefulness of porcine inner ear cell cultures to the study of human inner ear disorders.

Soft silicone has been widely used for anti-icing coating, but the ice adhesion strength is usually scaled with the iced area at a relatively large thickness. On the other hand, a thin rigid poly(vinyl chloride) (PVC) film could be independent of the iced area and was named a low-interfacial-toughness material. Thus, a soft and rigid integrated (SRI) coating was prepared by doping PVC particles into a silicone matrix here. The introduction of PVC particles not only served as phase II to accelerate the stress concentration but also favored the formation of a wrinkle structure. After further introducing plasticizers, this SRI coating not only has a very low ice adhesion strength at a low iced length but also tends to a limit value irrespective of the iced length, which further leads to excellent large-area deicing behavior. Furthermore, the SRI coating demonstrated outstanding chemical stability, mechanical robustness, and on-field repairability.

Imitation learning aims to extract knowledge from human experts' demonstrations or artificially created agents in order to replicate their behaviors. Its success has been demonstrated in areas such as video games, autonomous driving, robotic simulations and object manipulation. However, this replicating process could be problematic, such as the performance is highly dependent on the demonstration quality, and most trained agents are limited to perform well in task-specific environments. In this survey, we provide a systematic review on imitation learning. We first introduce the background knowledge from development history and preliminaries, followed by presenting different taxonomies within Imitation Learning and key milestones of the field. We then detail challenges in learning strategies and present research opportunities with learning policy from suboptimal demonstration, voice instructions and other associated optimization schemes.

Nonlinear mathematical model (NMM) of limited-angle torque motor (LATM) is rarely studied at present because its operating principle is different from conventional rotating electrical machines. In this article, inspired by the NMM of rotating electrical machines, a high-fidelity and computationally efficient model of LATM is proposed, which can completely consider the nonlinear effects, including the electromagnetic torque, flux linkage, and inductance variation with current and rotor position due to magnetic saturation in the stator core. Different from the field-circuit coupling approach (FCCA) considering nonlinear effects, the proposed model exhibits higher computational efficiency since a finite element analysis (FEA) is not involved in the time-stepping simulation. Based on the high-fidelity model, an LATM position-tracking system model is built to simulate the real operation of the LATM system, which provides an accurate means of assessing the position-tracking performance without the actual test platform. The high fidelity of the proposed LATM model is validated by both the FCCA and experimental results.

Sympathetic stimulated-cardiac fibrosis imposes great significance on both disease progression and survival in the pathogenesis of many cardiovascular diseases. However, there are few effective therapies targeting it clinically. The cardioprotective effect of aldehyde dehydrogenase 2 (ALDH2) has been explored in many pathological conditions, whether it can exert benefit effects on chronic sympathetic stimulus-induced cardiac fibrosis remains unclear. In this study, we determined to explore the role of ALDH2 on isoproterenol (ISO)-induced cardiac fibroblasts (CF) proliferation and cardiac fibrosis. It was found that ALDH2 enzymatic activity was impaired in ISO-induced HCF proliferation and Aldh2 deficiency promoted mouse CF proliferation. Alda-1, an ALDH2 activator, exerted obvious suppressive effect on ISO-induced HCF proliferation, together with the induction of cell cycle arrest at G0/G1 phase and decreased expression of cyclin E1 and cyclin-dependent kinase 2 (CDK2). Mechanistically, the inhibitory role of Alda-1 on HCF proliferation was achieved by decreasing mitochondrial reactive oxygen species (ROS) production, which was partially reversed by rotenone, an inducer of ROS. In addition, wild-type mice treated with Alda-1 manifested with reduced fibrosis and better cardiac function after ISO pump. In summary, Alda-1 alleviates sympathetic excitation-induced cardiac fibrosis via decreasing mitochondrial ROS accumulation, highlighting ALDH2 activity as a promising drug target of cardiac fibrosis.

Dual three-phase (DTP) permanent magnet synchronous machines (PMSM) have been utilized in many applications due to their outstanding performance. However, large stator current harmonics limit the further application of the DTP-PMSM due to the low impedance in the harmonic subspace. To solve this problem, this article proposes a current harmonic suppression strategy based on an extended state observer (ESO). A detailed analysis is carried out to demonstrate the disturbance rejection ability and robustness of the proposed method. The theoretical analysis also shows that the ESO strategy outstands the conventional proportional-integral controller and advanced proportional resonance (PR) controller in terms of harmonic reduction. The advantages are verified by simulation and experimental results under different operating conditions. The proposed strategy still works well when considering other factors that may cause harmonic distortion, such as magnetic circuit saturation, saliency ratio, over-modulation of the inverter, the voltage drop caused by electric devices, and dead time. Meanwhile, some limitations are also pointed out. The proposed strategy can also be easily applied to other multiphase PMSM types.

In oil exploitation, the short maintenance period and the poor real-time performance of dynamometer card sensors limit the timely working state diagnosis for sucker rod pumps (SRP). The motor is the power source of the SRP that provides all the energy required to lift the oil from underground to surface. The motor power output is highly associated with the working state of the entire equipment. Thus, this article proposes a new strategy to predict the working state of SRP based on motor power. First, seven novel features are extracted from motor power data to support the modeling and diagnosing processes, with the consideration of the significant parameters such as valve's working points and the operating cycle of SRP. Moreover, a custom-designed multiple hidden conditional random fields model with time window is employed as the classifier to identify different working states. At last, the proposed method is validated by a set of motor power data collected from wells by a self-developed device. The experimental result demonstrates the effectiveness of the proposed method for the working state diagnosis of SRPs.

Non-coding RNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs/miRs), have significant regulatory effects on a number of biological processes in myocardial ischemia/reperfusion (I/R) injury, including cell differentiation, proliferation and apoptosis. In the present study, the expression levels of lncRNAs, miRNAs and mRNAs were evaluated in a mouse model of myocardial I/R injury. The potential functions of these differentially expressed genes were then analyzed via Gene Ontology and pathway analyses. Additionally, the interactions between lncRNA-miRNA-mRNA were predicted by constructing a competing endogenous RNA regulatory network. It was found that 14,366 lncRNAs, 151 miRNAs and 9,377 mRNAs were differentially expressed in mice hearts after I/R compared with the Sham group (fold change >2; P

Summary Background In patients with papillary thyroid cancer (PTC) with clinical negative central lymph nodes (cN0), the use of prophylactic central lymph node dissection remains controversial. Contralateral central lymph node metastasis (CCLNM) occurs in 3.88–30.63% of patients with cN0 PTC. Therefore, the present meta-analysis aimed to obtain evidence for CCLNM risk factors in unilateral cN0 PTC. Materials and methods Relevant studies were identified in the PubMed, SCIE, and Wanfang databases up to Oct 31, 2019. The included patients had undergone lobectomy or total thyroidectomy with bilateral central lymph node dissection and were diagnosed pathologically with PTC. Revman 5.3 software was applied for statistical analysis. Results Thirteen studies comprising 2449 patients were included. The factors associated with increased CCLNM risk in patients with cN0 disease were: age P P = 0.0007), extrathyroidal extension (OR = 1.63; 95% CI = 1.17–2.28; P = 0.004), tumor size ≥1 cm (OR = 2.63, 95% CI 1.85–3.74, P P P Conclusion The meta-analysis identified that age

Acute pancreatitis (AP) is one of the leading causes of hospital admission for gastrointestinal disorders. Although lipid peroxides are produced in AP, it is unknown if targeting lipid peroxides prevents AP. This study aimed to investigate the role of mitochondrial aldehyde dehydrogenase 2 (ALDH2), a critical enzyme for lipid peroxide degradation, in AP and the possible underlying mechanisms. Cerulein was used to induce AP in C57BL/6 J male mice and pancreatic acinar cells were used to elucidate underlying mechanisms in vitro. Pancreatic enzymes in the serum, lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), and Bcl-2, Bax and cleaved caspase-3 were measured. ALDH2 activation with a small-molecule activator, Alda-1, reduced the levels of the pancreatic enzymes in the serum and the lipid peroxidation products MDA and 4-HNE. In addition, Alda-1 decreased Bax and cleaved caspase-3 expression and increased Bcl-2 expression in vivo and in vitro. In conclusion, ALDH2 activation by Alda-1 has a protective effect in cerulein-induced AP by mitigating apoptosis in pancreatic acinar cells by alleviating lipid peroxidation.

Objective: To explore the biomechanical efficacy of arthroscopic all-inside anterior talofibular ligament (ATFL) suture augmentation repair, plus suture augmentation repair and anterior tibiofibular ligament-distal fascicle (ATiFL-DF) transfer augmentation repair, so as to provide a basis for the accurate selection of ATFL repair in clinical practice. Methods: Twenty-four (12 pairs) fresh frozen human cadaver ankle specimens were used. Six of the ankle specimens were set as the normal group, and the other 18 ankle specimens were used to establish ATFL injury models. The ATFL was then repaired using arthroscopic all-inside ATFL suture augmentation repair (suture augmentation group), plus suture augmentation repair (plus suture augmentation group) and ATiFL-DF transfer augmentation repair (biological augmentation group), respectively. After the repaired ATFL was separated, the ankle specimens were fixed on an electronic universal testing machine with a customized fixture for the tensile test, and the ultimate failure load (N) and stiffness (N/mm) of the ankle specimens were compared. Results: The ultimate failure load of the plus suture augmentation group (229.3 ± 66.7 N) was significantly higher than that in the normal group (148.2 ± 39.4 N, p = 0.045) and the biological augmentation group (131.3 ± 38.8 N, p = 0.013). There was no statistical difference in ultimate failure load between the suture augmentation group (167.2 ± 47.2 N), the normal group and the biological augmentation group. The stiffness of the plus suture augmentation group (26.2 ± 8.2 N/mm) was significantly higher than that in the normal group (12.1 ± 3.8 N/mm, p = 0.005) and the biological augmentation group (12.7 ± 5.2 N/mm, p = 0.007). The stiffness of the suture augmentation group (23.6 ± 7.0 N/mm) was significantly higher than that in the normal group (p = 0.024) and the biological augmentation group (p = 0.033). There was no statistical difference in stiffness between the plus suture augmentation group and the suture augmentation group, and no statistical difference in stiffness between the normal group and the biological augmentation group. Conclusions: The tensile strength and rigidity of plus suture augmentation repair were significantly better than those of normal ATFL, suture augmentation repair and ATiFL-DF transfer augmentation repair. Suture augmentation repair can obtain tensile strength similar to normal ATFL and ATiFL-DF transfer augmentation repair, and suture augmentation repair can obtain rigidity significantly better than normal ATFL and ATiFL-DF transfer augmentation repair. ATiFL-DF transfer augmentation repair can obtain tensile strength and rigidity similar to normal ATFL.

BackgroundBilateral lesions are common in papillary thyroid carcinoma (PTC). For patients with unilateral PTC, occult carcinoma that is not detected preoperatively, but pathologically after surgery, might remain in the contralateral lobe. In this situation, inadequate surgical extent could cause relapse and even lead to re-operation. Here, we explore the frequency and investigate the risk factors of contralateral occult PTC in unilateral PTC through a retrospective study conducted by our team and published articles online, respectively.MethodsWe collected the patients’ clinical data in our hospital, whose cancer was determined to be confined to the unilateral lobe by preoperative image examination (N = 204). These patients underwent initially total or near-total thyroidectomy and included their clinical data in the meta-analysis. We searched related literature in the PubMed, Embase, MEDLINE, Cochrane, and Web of Science databases until December 7, 2020, in order to perform a meta-analysis. The relevant articles were examined and the eligible studies were included to assess the association between clinicopathologic factors and contralateral occult PTC.ResultsThe meta-analysis included nine studies (involving 4347 patients). Of these, eight studies were from the databases, and one study was our retrospective data. The meta-analysis showed that the prevalence of contralateral occult PTC was 26.6% in all patients. A tumor size > 1 cm, ipsilateral multifocality, contralateral benign nodule, and central lymph node metastasis were significantly associated with contralateral occult PTC. In contrast, sex, age, ETE, capsular invasion, BRAF mutation, Hashimoto thyroiditis, and lateral lymph node metastasis were insignificantly associated with contralateral occult PTC.ConclusionThe meta-analysis identified a tumor size > 1 cm, ipsilateral multifocality, contralateral benign nodule, and CLNM as being significant risk factors for contralateral occult PTC. These findings may guide the extent of surgery in unilateral PTC patients.

Dual three-phase permanent magnet synchronous motor (PMSM) is a major area of interest within the field of motors since it inherits the advantages of both the PMSM and multiphase machines. While dual three-phase PMSM (DTP-PMSM) system has a more severe carrier frequency harmonic problem due to the low impedance in the harmonic subspace, which will not only decrease the efficiency but also produce the high-frequency audible noise. This study proposes an improved space vector pulse-width modulation (SVPWM) strategy by changing the sequence of the pulse-width modulation wave. The improved SVPWM strategy with a 10 kHz carrier frequency has the same effect as the conventional SVPWM with a 20 kHz carrier frequency, which will significantly decrease the switching loss, lead to lower size of inductance, capacitance and eliminate the high-frequency audible noise. Three existing mainstream SVPWM strategies in DTP-PMSM system are introduced and the proposed strategy can be used in them without affecting their original advantages. The switching times are also minimised to reduce the switching loss. The theoretical derivation is proposed to prove the harmonic suppression ability of the proposed SVPWM and the implementation procedure is given then. The simulation and experimental results proved the effectiveness of the strategy.

The dynamometer cards (DC) are the data shown as closed curves collected from Sucker Rod Pumps, which are essential evidence to monitor the working states in modern oil are engineering. To meet the actual needs of oil fields, recently, the computer-aided diagnosis techniques are becoming useful measurements to help engineers monitoring the wells. Nevertheless, how to collect the various kinds of fault data from a well is always a puzzle for the application of the computer-aided methods, because of a well hardly experiences many types of faulty working states. The typical solution for this problem is building an album containing DCs collected from different wells, but this approach neglects the property differences between wells, which may influence the diagnosis accuracy. In order to address this tough issue, in this paper, a novel approach regarding generating DCs is proposed based on the analysis of the mechanism of a sucker rod pump (SRP) at normal and several faulty scenarios. This method could use the productive parameters and operation rules of a well to calculate the DCs at different working states based on dynamic mechanism analysis. Subsequently, according to the data support of generating DCs, the Hidden Markov Models under a specifically designed framework is used to build the relationships between DCs and working states. At last, the proposed method is verified experimentally through the productive parameters of many wells collected from an oilfield, and then some conventional techniques are employed in the comparison studies. The obtained results demonstrate the effectiveness of the proposed method for diagnosing the working states of Sucker Rod Pumps.

Computer-aided fault detection for sucker rod pump is a crucial technology to monitor wells in the oil production. According to the detection results, engineers could take corresponding measures to ensure wells operating in a safe and productive state. Generally, the conventional approaches to address this problem are mainly based on dynamometer cards, but these methods have obvious defects in security risks and high maintenance cost in the application. Noteworthy, the motor is the energy resource of sucker rod pump and the change of motor’s power could reflect the variation of the working states. Therefore, in this paper, a novel method based on motor power for detecting the working state of the sucker rod pump is proposed. In this method, a set of the labeled motor power curve is essential. To obtain this vital information resource, the motor power curves are labeled by transforming them into dynamometer cards, which fully consider many crucial factors in this process. Moreover, to obtain useful information from motor power data, eight novel features are defined by analyzing the mechanism of motor work and the data distribution of the curve. Subsequently, the hidden Markov model (HMM), a probabilistic model with the double stochastic process, is employed to map the relationships between motor power data and working states. At last, the proposed method is verified experimentally using an oil dataset collected from oil field including six different working states, and then this technique is compared with some other methods. In the comparison, the proposed method gives 91.7% correct diagnosis that is higher than the 72.9% of SVM and the 62.5% of ANN. The experimental results show that the performance using the method proposed in this paper is satisfactory.

Due to its 2D-layered structure, MoS2 has drawn a lot of attention in energy storage device. Herein, yolk–shell MoS2 (YS-MoS2) microspheres were fabricated through a facile hydrothermal method with the presence of PEG-800. Both the shell and the core of the microsphere are composed of numerous self-assembly ultrathin nanosheets. In addition, the interlayer spacing of the synthesized YS-MoS2 is larger than the standard value of MoS2. As a supercapacitor electrode material, the YS-MoS2 showed high specific capacitance (343.0 F·g−1 at 0.25 A·g−1) and excellent cyclic stability (120% of the initial specific capacitance was retained after 1000 cycles at 2.0 A·g−1). The excellent electrochemical performances of synthesized YS-MoS2 may be ascribed to its yolk-shell structure, hierarchical porous structure and expanded interlayer spacing.

This paper introduces the SemEval-2021 shared task 4: Reading Comprehension of Abstract Meaning (ReCAM). This shared task is designed to help evaluate the ability of machines in representing and understanding abstract concepts.Given a passage and the corresponding question, a participating system is expected to choose the correct answer from five candidates of abstract concepts in cloze-style machine reading comprehension tasks. Based on two typical definitions of abstractness, i.e., the imperceptibility and nonspecificity, our task provides three subtasks to evaluate models’ ability in comprehending the two types of abstract meaning and the models’ generalizability. Specifically, Subtask 1 aims to evaluate how well a participating system models concepts that cannot be directly perceived in the physical world. Subtask 2 focuses on models’ ability in comprehending nonspecific concepts located high in a hypernym hierarchy given the context of a passage. Subtask 3 aims to provide some insights into models’ generalizability over the two types of abstractness. During the SemEval-2021 official evaluation period, we received 23 submissions to Subtask 1 and 28 to Subtask 2. The participating teams additionally made 29 submissions to Subtask 3. The leaderboard and competition website can be found at https://competitions.codalab.org/competitions/26153. The data and baseline code are available at https://github.com/boyuanzheng010/SemEval2021-Reading-Comprehension-of-Abstract-Meaning.

The human inner ear compared with that of other mammalian species is very complex. Although the mouse’s cochlea is frequently studied the mouse’s inner ear continues to develop postnatally whilst the human inner ear is fully developed by the third month of gestation which leads one to question the applicability of findings based on research on mice to human regenerative therapies. Here, we report a novel in vitro culture of adult porcine (Sus scrofa) inner ear cells developed from post-mortem labyrinth specimens. Anatomical findings based on maximal transverse and vertical axial diameters and the length of the cochlear duct suggest that the pig’s cochlea is similar to the human cochlea. In vitro cultures of porcine cochlear and vestibular cells showed the persistence of both inner ear hair cell (HC), supporting cell (SC) and stem/progenitor cell characteristics across passages up to 6 based on scanning electron microscopy, fluorescence immunocytochemistry and quantitative reverse transcription polymerase chain reaction (RT-qPCR). Our findings showed that porcine cochlear and vestibular epithelia maintained multipotent stem/progenitor cell populations into adulthood although their regenerative capacities differed across the passages. The development of a viable and reproducible method to culture porcine inner ear cells provides an important investigative tool that can be utilized to study and evaluate the pathophysiological causes and cellular consequences of human inner ear disorders.

It is generally believed that firms' engagement in Corporate Social Responsibility (CSR) activities can effectively reduce their cost of capital. This article provides value insights to the inverse relationship between the CSR rating and the cost of debt (COD). We first investigate the determinants of CSR ratings from both executive level and the firm’s level. Various board-related factors are associated with different dimensions of the CSR rating. We demonstrate that CSR is negatively associated with COD measured by interest paid over total debt. The relationship is most obvious when CSR rating is lagged by one period relative to COD, implying the time effect of CSR on COD. This effect is also most relevant in large size companies. Further analysis shows an increase in CSR leads to higher probability of decrease in COD and vice versa.

Background Bladder urothelial carcinoma (BLCA), one of the most common urinary system malignancies, has a high morbidity and metastasis rate. The enhancer RNAs (eRNAs), are derived from enhancer regions and contribute to enhancer function, whereas their roles in BLCA tumorigenesis and bone metastasis are still unclear.Method The RNA sequencing data of patients with BLCA were retrieved from The Cancer Genome Atlas (TCGA) databases and the normalized gene expression profile of eRNA in BLCA (annotated by Ensemble ID) were downloaded from the eRic database. The differential expression eRNAs and genes were evaluated and identified between primary BLCA with and without bone metastasis. The prognostic bone metastasis-specific eRNAs (PBMSEs) were screened by Lasso regression, and based on them, the risk scores were identified and predict models were constructed. Their accuracy were tested by the area under the curve (AUC) of the receiver operator characteristic (ROC) curve. Additionally, in order to explore the bone metastasis-specific regulation network, the relationship among key PBMSEs, differentially expressed target genes of eRNAs and signaling pathways were identified by Pearson correlation analysis. ResultsA total of 832 eRNAs were detected, with 37 PBMSEs annotated by Ensemble ID in univariate Cox regression analysis. Based on them, the first prediction model was constructed with the AUC of 0.920. Besides, we uncovered 166 DEGs between primary BLCA with and without bone metastasis. A total of 23 eRNAs and 109 target genes annotated by official gene symbol were uncovered in which31 PBMSEs and target genes revealed prognostic. Based on them, another prediction model was constructed with the AUC of 0.742. Moreover, we identified EMP1 as a PBMSE which regulated the target genes of APOLD1 and GPRC5A, and tumorigenesis-related pathways of KRAS signaling, inflammatory response, IL2-stat5 signaling and epithelial mesenchymal transition (EMT).Conclusion Our study identifies eRNAs as reliable indexes for prognosis and bone metastasis prediction in BLCA patients and provides well-applied prediction models for them. The bone metastasis-specific regulation network was also explored in which PBMSE (EMP1) could mediate target genes (APOLD1, GPRC5A) and tumorigenesis-related pathways (KRAS signaling, inflammatory response, EMT) in the tumorigenesis and bone metastasis of BLCA.

It is generally difficult to obtain accurate optimisation functions during parameters matching and optimisation process of the hybrid system, especially in the optimisation variable field containing both a continuous set and a discontinuous set and when the control strategy has an important influence on the system performance. To aim at the fuel economy of the parallel hydraulic hybrid system, a global parameter matching and control strategy based on the simulation model were proposed. The AMESim simulation model as the judgment module of the optimisation algorithm was used to match and optimise the main parameters and control strategies in the hybrid system. The communication of underlying parameters was developed by the VBA in EXCEL platform. Parameters match was implemented on a truck crane chassis in practice. The test results indicated that the rate of fuel saving reached 15.2%, which was generally consistent with the theoretical analysis. The parameters were met the energy-saving requirements of hybrid vehicles.

Magnesium is a biodegradable material that has potential application in cardiovascular stent development: its excellent mechanical properties and blood compatibility make it highly useful in interventional therapy. Nevertheless, the following shortcomings restrict its further application: antihyperplasia function and promoting surface endothelialization. In this study, we immobilized a specific link peptide of endothelial cells, Arg-Glu-Asp-Val (REDV), onto polydopamine (PDA)-deposited Mg–Zn–Y–Nd alloy surface via covalent reaction to improve the growth of the endothelial cells. The PDA/REDV coating with optimized parameters maintained the good blood compatibility of the Mg–Zn–Y–Nd alloy at the biomimetic speed of the blood flow and significantly inhibited the growth of the vascular smooth muscle cells and macrophage attachment/activation, which indicated its better functions in antihyperplasia and anti-inflammation. In particular, the PDA/REDV coating not only showed consistent results in promoting the attachment of endothelial cells as reported elsewhere, but also displayed the ability of enhancing the viability of endothelial cells (or inhibiting apoptosis), suggesting its pro-endothelialized function through different pathways. In summary, this PDA/REDV coating addressed the above-mentioned shortcomings of the magnesium alloy, which may promise its wider application.

In this study, an over-current protection method for permanent magnet synchronous motor (PMSM) voltage source inverter (VSI) employing small DC-link capacitor is proposed. Since VSI with small DC-link capacitor has become popular for its long lifetime and compactness. However, the small DC-link capacitor brings the risk of excessive voltage in the DC-link capacitor when the traditional `all-turn-off' over-current protection is utilised. In order to avoid the damage for VSI caused by excessive pumping-up voltage, based on the analysis for the `all-turn-off' method, the proposed method could eliminate reversal current flowing into the DC-link capacitor through switching logic. Consequently, the electro-magnetic energy stored in PMSM windings is converted into mechanical energy and pumping-up voltage is cancelled. Detailed analysis of the proposed method is presented. The effectiveness of the proposed method is verified by simulation and experiments.

In oil field production, dynamometer card is the key source of information to analyze the down-hole operating conditions of sucker rod pumping. However, under different operating conditions, most of the existing diagnostic technologies are incapable to extract features from dynamometer cards automatically and comprehensively. Based on the mechanism analysis of dynamometer card, a useful diagnostic method with novel feature extraction method is proposed for diagnosing the operating condition of sucker rod pumping. A novel barycentric decomposition strategy is applied to divide the dynamometer cards, which can automatically adjust divided regions according to the shape change of dynamometer card. The curve moments are extracted from the parts of divided results to obtain the comprehensive features for the follow-up algorithm. Subsequently, the hidden Markov model with mixture density function is designed as a classifier to map the relationship between the operating condition and the features of dynamometer card. This technique is successfully carried out in a fault dynamometer card atlas that is collected from productive field. Finally, the experimental results confirm the validity of the proposed diagnosis approach.

Down-hole operating condition diagnosis based on dynamometer card is a key subject for sucker rod pumping in oil extraction engineering. In this technology, feature extraction and diagnostic model are two indispensable elements. To accurately and automatically diagnose the operating condition by computer, a novel diagnostic method for sucker rod pumping is proposed. The first novel idea is to extract seven geometric features, which are obtained from dynamometer card using barycentric decomposition algorithm and valve working position. The second novel idea focuses on the use of continuous hidden Markov model (CHMM) to create classifiers for diagnosing the down-dole operating conditions and then clonal selection algorithm (CSA) is used to optimize the selection of initial parameters for CHMM. Finally, the proposed method is tested on an oil field dynamometer card set. Furthermore, this technique is compared with some other existing approaches. The simulation results demonstrate that the performance using the method proposed in this paper is satisfactory.