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Dynamic soft tissue identification plays an important role in robotic‐assisted minimally invasive surgery to achieve realistic force feedback for precise and safe surgical operations. This article studies a dynamic soft tissue identification method by combination of the Hunt Crossley contact model with an iterated Kalman filter. The dynamic system equation of tool‐tissue interaction is constructed by combining mechanical tool's kinematic dynamics with the Hunt Crossley contact dynamics. Upon this, an iterative Kalman filter is developed for online soft tissue identification by integrating the maximum a posteriori principle into the Kalman filtering framework to optimize the posterior state estimate to account for the strong nonlinearity of the Hunt Crossley contact model. Results and comparison analysis demonstrate that the proposed method can effectively identify the Hunt‐Crossley model parameters, resulting in improved accuracy compared with the conventional recursive least square method and extended Kalman filter. [ABSTRACT FROM AUTHOR]

In order to adapt to the development of lightweight equipment, and further improve the wear resistance of ZL109 aluminum alloy, the influence of nickel-coated carbon nanotubes as an electrolyte additive on the preparation and wear resistance of microarc oxidation ceramic coatings on ZL109 aluminum alloy surface was investigated. In this work, 0.4 g/L, 0.8 g/L, 1.2 g/L, 1.6 g/L, and 2 g/L nickel-coated carbon nanotubes were added to the electrolyte respectively. The microarc oxidation ceramic coatings were prepared under bipolar pulse constant pressure mode, which were analyzed from the aspects of morphology, chemical composition, and wear resistance property. The results show that the nickel-coated carbon nanotubes possess a great influence on ceramic coatings. The morphology of ceramic coatings was significantly changed. In this work, the coating prepared by 1.2 g/L nickel-coated carbon nanotubes exhibits excellent wear resistance property. [ABSTRACT FROM AUTHOR]

A composite ceramic coating containing h-BN particles was prepared on the ZL109 alloy via plasma electrolytic oxidation. The h-BN particles were modified by Polyethylene glycol to improve the dispersibility. The results revealed that the h-BN particles in the electrolyte were inertly incorporated into the coating. Meanwhile, the incorporation of h-BN particles can reduce the porosity and slightly increase the roughness of the composite ceramic coating. Furthermore, the growth rate of the coating and the conversion of γ-Al2O3 and α-Al2O3 were promoted by the incorporation of h-BN particles via the change of the current. In addition, due to the presence of h-BN particles, the composite ceramic coating had a lower friction coefficient and a lower wear rate under dry sliding condition. [ABSTRACT FROM AUTHOR]

Abstract: The ion penetration and diffusion technique with enhanced dielectric barrier discharge at atmospheric pressure is put forward in this paper. The fundamentals and characteristics of the ion penetration and diffusion technique are enlarged upon. The authors conducted some theoretical analysis and calculations. An experiment of ion penetration and diffusion technique with enhanced dielectric barrier discharge at atmospheric pressure was designed. The research result shows that white layers and diffusion layers on the treated steel surface are thicker than those achieved by normal plasma penetration technology within the same treated time. The total nitride layer thickness of 260 μm and the white layer thickness of 20 μm were achieved, and the surface hardness was about 1000 HV0.1, which was comparable to the normal glow discharging nitride result at low pressure. From the XRD pattern, the nitride layer was mainly compounded of γ′ and ε phases, which were finer than those obtained by normal glow discharge nitriding. [Copyright &y& Elsevier]

In this work, we introduce a chaotic system with infinitely many equilibrium points laying on two closed curves passing the same point. The proposed system belongs to a class of systems with hidden attractors. The dynamical properties of the new system were investigated by means of phase portraits, equilibrium points, Poincaré section, bifurcation diagram, Kaplan–Yorke dimension, and Maximal Lyapunov exponents. The anti-synchronization of systems was obtained using the active control. This study broadens the current knowledge of systems with infinite equilibria. [ABSTRACT FROM AUTHOR]

Chaotic systems with hidden attractors, infinite number of equilibrium points and different closed curve equilibrium have received much attention in the past six years. In this work, we introduce a new family of chaotic systems with different closed curve equilibrium. Using the methods of equilibrium points, phase portraits, maximal Lyapunov exponents, Kaplan–Yorke dimension, and eigenvalues, we analyze the dynamical properties of the proposed systems and extend the general knowledge of such systems. [ABSTRACT FROM AUTHOR]

In this paper we investigate the existence and multiplicity of homoclinic solutions for the following damped vibration problem: u¨+q(t)u˙−L(t)u+Wu(t,u)=0, where q:R→R is a continuous function, L∈C(R,Rn2) is a symmetric and positive definite matrix for all t∈R and W∈C1(R×Rn,R). The novelty of this paper is that, assuming lim|t|→+∞Q(t)=+∞ (Q(t)=∫0tq(s)ds) and L is coercive at infinity, we establish one new compact embedding theorem. Subsequently, supposing that W satisfies the global Ambrosetti-Rabinowitz condition, we obtain some new criterion to guarantee the existence of homoclinic solution of (DS) using the mountain pass theorem. Moreover, if W is even, then (DS) has infinitely many homoclinic solutions. Recent results in the literature are generalized and significantly improved. [ABSTRACT FROM AUTHOR]

Background: Ameloblastoma is an aggressively growing, highly recurrent odontogenic jaw tumor. Its association with BRAFV600E mutation is an indication for BRAFV00E‐inhibitor therapy The study objective was to identify a sensitive low‐cost test for BRAFV600E‐positive ameloblastoma. We hypothesized that immunohistochemical staining of formalin‐fixed paraffin‐embedded tissues for BRAFV600E mutation is a low‐cost surrogate for BRAFV600E gene sequencing when laboratory resources are inadequate for molecular testing. Methods: Tissues from 40 ameloblastoma samples were retrieved from either formalin‐fixed paraffin‐embedded blocks, RNAlater™ stabilization solution or samples inadvertently pre‐fixed in formalin before transfer to RNAlater™. BRAFV600E mutation was assessed by Direct Sanger sequencing, Amplification Refractory Mutation System‐PCR and immunohistochemistry (IHC). Results: BRAFV600E mutation was detected by IHC, Amplification Refractory Mutation System‐PCR and Direct Sanger sequencing in 93.33%, 52.5% and 30% of samples respectively. Considering Direct Sanger sequencing as standard BRAFV600E detection method, there was significant difference between the three detection methods (휒2 (2) = 31.34, p < 0.0001). Sensitivity and specificity of IHC were 0.8 (95% CI: 0.64–0.90) and 0.9 (95% CI: 0.75–0.99) respectively, while positive predictive value and negative predictive value (NPV) were 0.9 and 0.8 (Fischer's test, p < 0.0001) respectively. Sensitivity and specificity of Amplification Refractory Mutation System‐PCR detection method were 0.7 (95% CI: 0.53–0.80) and 0.9 (95% CI = 0.67–0.98) respectively, while PPV and NPV were 0.9 and 0.6 respectively (Fischer's test, p < 0.0001). Conclusion: Low‐cost and less vulnerability of IHC to tissue quality make it a viable surrogate test for BRAFV600E detection in ameloblastoma. Sequential dual IHC and molecular testing for BRAFV600E will reduce equivocal results that could exclude some patients from BRAFV600E‐inhibitor therapies. [ABSTRACT FROM AUTHOR]

The purpose of this work was to improve reliability and durability of high-silicon aluminum alloy piston skirts for diesel engines. Novel ceramic matrix composites were fabricated on ZL109 aluminum alloy substrates by two steps combining microarc oxidation (MAO) with electrophoresis deposition (EPD). MoS 2 is incorporated into an aluminum oxide matrix during processing. The effects of the ceramic matrix composites on anti-wear and self-lubricating were investigated using a reciprocating test method and cylinder liner samples (boron copper cast iron) as the sliding partner. Compared to the high-silicon aluminum alloys substrate, the friction coefficient of ceramic matrix composites against the liner material was reduced by 35% under dry sliding, the wear loss was decreased by 95%, the worn surfaces were flat and smooth, and friction coefficient was relatively stable. The mechanisms by which the observed advantages were produced are discussed. [ABSTRACT FROM AUTHOR]

A surface texture produced by three-step microarc oxidation (MAO) was optimized to improve the tribology performance of a self-lubricating composite coating for diesel engine piston skirts. WS 2 was introduced into the self-lubricating composite coating as a self-lubricating additive. The effects of MAO's varying electrical parameters in terms of stages and action time on the microstructure and chemical composition of the coatings were analyzed by XPS mapping, micron CT, SEM, XRD, and EDS mapping. Furthermore, friction-wear tests under dry lubricating were employed to evaluate the self-lubricating property of the composite coating. Compared to the bare ZL109 aluminum alloy, the optimized composite coating's friction coefficients were reduced by 60%. Notably, the wear loss of cylinder liner samples matched with the optimized composite coating was almost zero under this work condition. Image 1 • An optimized self-lubricating coating for Al–Si piston skirts was fabricated. • The surface texture was optimized for the self-lubricating coating. • Varying electrical parameters and action time were analyzed for the texture. [ABSTRACT FROM AUTHOR]

A corrosion-resistant non-crystalline coating was fabricated by plasma electrolytic oxidation (PEO) on Q235 low carbon steel for ship pipes. The distribution and composition of chemical elements and phases of PEO coatings were analyzed by an orthogonal experiment, and the formation mechanism of PEO coatings was discussed. The corrosion current densities and corrosion potentials were measured. The results indicated that the formation of a transition layer mainly containing Fe3O4 was crucial for achieving an excellent coating quality. Furthermore, the corrosion current density of coated steel was reduced by 78% compared with the bare steel. [ABSTRACT FROM AUTHOR]

INS/GNSS (inertial navigation system/global navigation satellite system) integration is a promising solution of vehicle navigation for intelligent transportation systems. However, the observation of GNSS inevitably involves uncertainty due to the vulnerability to signal blockage in many urban/suburban areas, leading to the degraded navigation performance for INS/GNSS integration. This paper develops a novel robust CKF with scaling factor by combining the emerging cubature Kalman filter (CKF) with the concept of Mahalanobis distance criterion to address the above problem involved in nonlinear INS/GNSS integration. It establishes a theory of abnormal observations identification using the Mahalanobis distance criterion. Subsequently, a robust factor (scaling factor), which is calculated via the Mahalanobis distance criterion, is introduced into the standard CKF to inflate the observation noise covariance, resulting in a decreased filtering gain in the presence of abnormal observations. The proposed robust CKF can effectively resist the influence of abnormal observations on navigation solution and thus improves the robustness of CKF for vehicular INS/GNSS integration. Simulation and experimental results have demonstrated the effectiveness of the proposed robust CKF for vehicular navigation with INS/GNSS integration. [ABSTRACT FROM AUTHOR]

Background: With the increasingly severe energy shortage and climate change problems, developing wind power has become a key energy development strategy and an inevitable choice to protect the ecological environment worldwide. The purpose of this study was to investigate the prevalence of low back pain (LBP) and analyze its risk factors among operation and maintenance personnel in wind farms (OMPWF).Methods: A cross-sectional survey of 151 OMPWF was performed, and a comprehensive questionnaire, which was modified and combined from Nordic Musculoskeletal Questionnaires (NMQ), Washington State Ergonomics Tool (WSET) and Syndrome Checklist-90(SCL-90) was used to assess the prevalence and risk factors of LBP among OMPWF.Results: The prevalence of LBP was 88.74 % (134/151) among OMPWF. The multivariable model highlighted four related factors: backrest, somatization, squatting and lifting objects weighing more than 10 lb more than twice per minute.Conclusions: The prevalence of LBP among OMPWF appears to be high and highlights a major occupational health concern. [ABSTRACT FROM AUTHOR]

Modified WS 2 by silane coupling agent were encapsulated in the dimples fabricated on the surface of cylinder liner samples by hot-pressing method. The tribological properties, anti-adhesion performance of the samples as well as the releasing behavior of modified WS 2 in the dimples were tested by a reciprocating tribotester. Moreover, the anti-erosion performance of modified WS 2 was examined by ultrasonic vibration test. The results indicate that the composite lubrication structure has good anti-friction and anti-adhesion effects. Furthermore, the release rate of WS 2 in the dimples is decreased by 102.2% due to the introduction of silane coupling agent. Additionally, the synergistic effect among the dimples, the solid lubricant and the silane coupling agent can explain the anti-friction and sustained release mechanisms. [Display omitted] • Modified WS 2 by silane coupling agent were encapsulated in the dimples. • The tribological properties and anti-adhesion performance were tested. • The release rate of WS 2 in the dimples were analyzed. • The synergetic lubrication mechanism was proposed [ABSTRACT FROM AUTHOR]

Integrated MIMU/GNSS/CNS (micro-electro-mechanical system-based inertial measurement unit/global navigation satellite system/celestial navigation system) is a promising strategy for UAV (unmanned aerial vehicle) navigation. However, given its strong nonlinearity and involvement of kinematic model error, integrated MIMU/GNSS/CNS UAV navigation presents the difficulty in achieving optimal navigation solutions. This paper presents a method of cubature rule-based distributed optimal fusion combined with identification and prediction of kinematic model error to address the above problem in nonlinear integrated MIMU/GNSS/CNS. This method is in a distributed structure to simultaneously process observations from integrated MIMU/GNSS and MIMU/CNS subsystems for the subsequent global fusion. A theory for identification of kinematic model error is established using the concept of Mahalanobis distance. Further, the standard cubature Kalman filter is modified with the model prediction filter to serve as the local filters in integrated MIMU/GNSS and MIMU/CNS subsystems to hinder the disturbance of kinematic model error. Based on the above, an optimal fusion technique is developed to fuse the filtering results of each subsystem for achieving globally optimal state estimation in the sense of mean square error. Simulations and experimental results as well as comparison analysis demonstrate that the proposed distributed optimal fusion method can effectively identify and predict kinematic model error and further achieve globally optimal fusion results, leading to improved performance for integrated MIMU/GNSS/CNS UAV navigation. [ABSTRACT FROM AUTHOR]

Ceramic based self-lubricating coating was successfully fabricated on Al-based plasma electrolytic oxidation (PEO) ceramic coating in this work. The coating was reinforced with thermosetting polyimide (PI) containing tungsten disulfide (WS 2) fillers. The morphology, chemical composition and phase structure of the PEO, PEO/PI and PEO/PI/WS 2 coatings were observed by SEM, EDS and XRD, respectively. Tribological properties of the coatings were comparatively investigated using a reciprocating pin-on-block tribotester under different conditions. Under dry sliding conditions, the friction coefficient of PEO/PI/WS 2 coating was about 0.4, which was 50% lower than that of PEO coating. Meanwhile, the wear rate of counter pin cooperated with PEO/PI/WS 2 coating was only 0.04 mg min−1, which was 90.9% lower than that of PEO coating. Under step loading conditions, the load was ultimately increased to 70 N and the total duration time was about 35 min, while the corresponding values of PEO coating were 30 N and 13 min, respectively. These are owed to the hard ceramic coating and the soft self-lubricating coating, which can improve the load capacity and decrease the friction, of the ceramic based self-lubricating coating. Image 1 • A self-lubricating coating was successfully fabricated on ZL109 aluminum alloy. • The introduction of WS 2 in the self-lubricating coating shows excellent tribological properties. • The combination of soft lubricating coating and hard supporting ceramic coating is the main anti-friction mechanism. [ABSTRACT FROM AUTHOR]