In this work, we utilize the quantum renormalization-group (QRG) method to investigate quantum phase transitions (QPT) in a one-dimensional anisotropic spin-1/2 XY model with Dzyaloshinskii–Moriya ...(DM) interaction. Within this model, it has been demonstrated that phase diagrams are influenced by both the anisotropy parameter and DM interaction strength. Particularly noteworthy is our identification of QPT in global entanglement (GE) and tripartite negativity as the number of QRG iterations increases, allowing for a clear distinction between the Spin-fluid and Néel phases. Additionally, both GE and tripartite negativity decrease with rising anisotropy parameter, eventually stabilizing. However, we have observed that the robustness of tripartite negativity exceeds that of GE. To gain deeper insights, we conduct a detailed analysis of the first derivative of GE, unveiling scaling and nonanalytic behavior at the critical point. Our findings provide crucial insights into multipartite entanglement dynamics in condensed matter systems, significantly advancing our understanding of the quantum critical properties in Heisenberg spin models.
The uncertainty principle is regarded as one of basics in quantum mechanics, which sets up a strict lower bound to quantify the prediction on the outcome concerning a set of incompatible ...measurements. In this paper, we investigate the dynamic behaviors of quantum-memory-assisted entropic uncertainty relation (EUR), and quantum coherence in structured reservoir. The results shown that the EUR is smallest in the vanishing limit of noise regardless of the forms of the initial sate we considered, while the coherence keeps the maximal value. During the time-evolution process, the uncertainty bound is lifted and the coherence damps monotonously. Subsequently, the EUR converges to an asymptotic nonzero constant in the long-time limit, yet the coherence asymptotically decays to zero. Moreover, the initial state purity plays a deterministic role in the initial amounts of EUR and coherence, i.e. the larger purity the less EUR and larger coherence. As an application, we employ the EUR to witness the coherence, and prove that the corresponding witnessing efficiencies are only depended on the version of coherence, while are insensitive to the reservoir.
Based on quantum renormalization group (QRG) method, we investigated quantum coherence and quantum phase transition (QPT) in XXZ chain and XY chain, respectively. The results show that both the ...geometric quantum coherence and entropic coherecne can accurately indicate the QPT at critical point after enough iteration steps. Moreover, the increasing anisotropy parameter destroys the coherence in the XXZ chain, while enhances it in the XY chain. In addition, focused on the XXZ chain we analyzed the nonanalytic phenomena and scaling behaviors with different theoretical exponents in detail.
This paper proposes a novel pupil and glint detection method for gaze tracking system using a wearable camera sensor and near-infrared LED array. A novel circular ring rays location (CRRL) method is ...proposed for pupil boundary points detection. Firstly, improved Otsu optimal threshold binarization, opening-and-closing operation and projection of 3D gray-level histogram are utilized to estimate rough pupil center and radius. Secondly, a circular ring area including pupil edge inside is determined according to rough pupil center and radius. Thirdly, a series of rays are shot from inner to outer ring to collect pupil boundary points. Interference points are eliminated by calculating gradient amplitude. At last, an improved total least squares is proposed to fit collected pupil boundary points. In addition, the improved total least squares developed is utilized for the solution of Gaussian function deformation to calculate glint center. The experimental results show that the proposed method is more robust and accurate than conventional detection methods. When interference factors such as glints and natural light reflection are located on pupil contour, pupil boundary points and center can be detected accurately. The proposed method contributes to enhance stability, accuracy and real-time quality of gaze tracking system.
Reliable lubrication is the key to ensure the safe service of space equipment moving parts, but the tribological performance of most lubricating materials in a vacuum environment is substantially ...degraded. Therefore, graphene/diamond-like carbon (DLC) coatings were prepared on 9Cr18 bearing steel substrates using a combination of radio frequency (RF) magnetron sputtering preparation of DLC coatings and airbrush coating graphene layers, and the structural characteristics and tribological properties of the coatings were comparatively investigated for the different times of graphene layer spraying. The results shows that the graphene surface layer formed a stable bond with the DLC substrate, but there were local wrinkles in the graphene sheets deposited by the airbrush, and the surface roughness of the coating increased with the increase of the spraying times. The graphene/DLC coating with 3 times spraying has relatively excellent tribological properties in vacuum, with an average coefficient of friction of about 0.08 and a wear rate of 4.59 × 10−7 mm3N−1 m−1. Based on the tribological testing results, the mechanism of the friction-reduction and wear reduction of the graphene/DLC coatings in vacuum were analyzed. In general, the graphene/DLC coatings have excellent tribological properties in vacuum and hold significant promise for applications in moving parts of aerospace equipment.
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•Graphene/DLC coatings were prepared on 9Cr18 bearing steel by combined radio frequency magnetron sputtering and gun spraying.•The graphene sheet layer spread unevenly on the DLC coating surface in a wrinkled state, and the roughness increased with the times of graphene spraying.•The non-metric stacking of graphene sheet layers and the formation of "micro-bearings" during the friction process were the main reasons for the excellent tribological properties of the graphene/DLC composite coatings in vacuum.
Despite successful clinical applications, teleoperated robotic surgical systems face particular limitations in the functional endoscopic sinus surgery (FESS) in terms of incompatible instrument ...dimensions and robot set-up. The endoscope remains manually handled by an assistant when the surgeon performs bimanual operations. This paper introduces the development of the Foot-controlled Robot-Enabled EnDOscope Manipulator (FREEDOM) designed for FESS. The system features clinical considerations that inform the design for providing reliable and safe endoscope positioning with minimal obstruction to the routine practice. The robot structure is modular and compact to ensure coaxial instrument manipulation through the nostril for manual procedures. To avoid rigid endoscope motions, a new compliant endoscope holder is proposed that passively limits the lens-tissue contact forces under collisions for patient-side protection. To facilitate hands-free endoscope manipulation that imposes minimal distractions to the surgeon, a foot-wearable interface is further designed to relieve the assistant's workload. The foot control method owns a short learning curve (mean 3.4 mins), and leads the task to be more ergonomic and surgeon-centered. Cadaver and clinical studies were both conducted to evaluate the surgical applicability of the FREEDOM to assist endoscope manipulation in FESS. The system was validated to be safe (IEC-60601-1) and easy for set up (mean 3.6 mins), from which the surgeon could perform various three-handed procedures alone in FESS without disrupting the routine practice.
Quantum coherence (QC) as a crucial physical resource plays the vital role in recent researches of quantum information science, whereas the QC within an open system unavoidably deteriorates due to ...the system–environment interacting. In this paper, we analyze the dynamics of QC when the initial state is exposed to Markovian and non-Markovian reservoirs, respectively. We analytically derive the dynamical conditions under which the QC is frozen in the Markovian reservoir and explore the underlying physical mechanisms by investigating the trade-off relation between QC and mixedness of system. In the non-Markovian reservoir, we demonstrate the damped revivals of QC and show that these revivals can be effectively enhanced by increasing the memory degree of reservoir. These findings might provide an insightful physical interpretation for the dynamical phenomena of QC exhibiting in complex systems.
In order to explore the influence of space ultraviolet radiation on spacecraft lubricating materials, an in-situ friction experimental device simulating space ultraviolet radiation was developed in ...the laboratory, and the experimental verification was carried out. This paper firstly introduced the design index, structure and working principle of the space ultraviolet irradiation simulation device, and then calibrated and tested the parameters of the whole device, and also conducted a virtual operation of the device's operation effect by simulation software, and the results showed that it met the design index. Finally, the validation tested of the ultraviolet irradiated in-situ friction experimental device were described in detail. By using the device to irradiate the samples, it was found that the in-situ ultraviolet irradiation device could achieve the expected irradiation effect, and the irradiation would lead to changes in the surface structure and properties of the PTFE material, while also achieving the need for in-situ spatial friction property testing of the material, providing favorable conditions for future testing.
Compared to conventional linear and circular segments, the parametric curve has advantages in approximating and machining, guaranteeing higher machining precision and better machining quality. ...Therefore, in Computer Numerical Control (CNC) systems, parametric toolpath has become more and more popular for its high-performance in practical machining and the performance of the parametric interpolator has become a standard to illustrate the advanced CNC systems. In this paper, adaptive-feedrate planning and the iterative interpolator have been developed to generate sampling points with respect to error and higher order kinematic constraints. Firstly, a jerk-limited feedrate profile and look-ahead algorithm are utilized to provide reachable feedrate at critical points. Afterwards, normal jerk (i.e. the jerk in a normal direction) are limited to improve machining precision and quality. In theory, it is proved that the normal jerk limitations have relationship with curvature derivative and a novel iterative interpolator is proposed to ensure the normal jerk limitation by considering the corresponding constraints at curvature derivative extreme points. Finally, simulation and experiments are conducted to demonstrate the efficiency and contour performance of the proposed method compared to conventional method and time-optimal method.
To investigate atomic oxygen effects on tribological properties of Mo/MoS2-Pb-PbS film and further enlarge application range, atomic oxygen exposure tests were carried out for 5 h, 10 h, 15 h, and 20 ...h by the atomic oxygen simulator with atomic oxygen flux of 2.5 × 1015 atoms/cm2·s. The exposure time in test was equivalent to the atomic oxygen cumulative flux for 159.25 h, 318.5 h, 477.75 h, and 637 h at the height of 400 km in space. Then, the vacuum friction test of Mo/MoS2-Pb-PbS thin film was performed under the 6 N load and 100 r/min. By SEM, TEM, and XPS analysis of the surface of the film after atomic oxygen erosion, it was observed that atomic oxygen could cause serious oxidation on the surface of Mo/MoS2-Pb-PbS film, and the contents of MoS2, PbS, and Pb, which were lubricating components, were significantly reduced, and oxides were generated. From AES analysis and the variation in the main element content, Mo/MoS2-Pb-PbS thin film showed self-protection ability in an atomic oxygen environment. Hard oxide generated after atomic oxygen erosion such as MoO3 and Pb3O4 could cause the friction coefficient slight fluctuations, but the average friction coefficient was in a stable state.
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