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Recently, flexible strain sensors with excellent stretchability and sensitivity have attracted increasing interests. Most flexible strain sensors have multifunctional applications in human motion monitoring, transparent and wearable electronic systems, however, they also can be applied in other fields such as structural health monitoring (SHM). In this paper, a flexible strain sensor which was assembled by adhering graphene mesh film on liquid crystal polymer substrate constructed by an efficient, low-cost fabrication strategy for applying in SHM is presented. By means of monitoring the relative resistance change of graphene mesh film of the strain sensor, the strain caused by the minor displacement of the structure could be detected. The experiment results showed that the strain sensor had a high gauge factor (375–473) under different tensile strain (0.1–1.4%) and good stability (1000 test cycles). It can be verified that the sensor has high sensitivity and good stability, which makes it have potential application in SHM. [ABSTRACT FROM AUTHOR]

A piezoresistive pressure sensor with the electrostatic self-detecting structure was developed in the paper, which can solve the issue of low efficiency and time-consuming drawbacks of the traditional method in testing and calibrating the sensor with the specialized equipment. The theoretical model of the composite membrane piezoresistive sensor was established, the analytical model of the electrostatic force driven by an electrostatic voltage was obtained, a feasible fabrication process based on flip-chip process was proposed based on the MEMS processing, the pressure sensor and its detection structure were manufactured to verify the validity of the model in the paper. From the experiment results, it can be verified that the sensitivity of the pressure sensor was 1.77 mV/hPa and the non-linearity was 1.19% respectively. At the same time, the electrostatic force used to test sensor calibration could replace the loaded pressure in the range between 110 and 500 hPa. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) ceramics play a key role in various engineering applications due to their desirable properties, however, they are typical hard-brittle materials and famous for their poor machinability. Ultrasonic-assisted grinding, a processing method hybridizing the conventional grinding and ultrasonic vibration (UV) machining, is employed as the one applicable machining method for hard-brittle materials. This study focuses on internal grinding of SiC ceramics with the assistance of the UV, and its ductile-brittle transition behavior in the grinding process were investigated experimentally. Following the processing principal of internal grinding and UV machining (i.e., UV-assisted internal grinding, UVAIG), the UVAIG experiment rig were constructed. Conventional internal grinding (CIG) tests, i.e., internal grinding without UV, were also performed on the constructed rig for comparison. In addition, the grinding force and the grinding chips variation behavior with the UV amplitude were also investigated to explore the ductile-brittle transition mechanism in UVAIG. The experiment results evidence that (1) ductile mode grinding is easily achieved in UVAIG, and the critical depth of the cut is deeper in UVAIG than that in CIG, i.e., 0.072 μm in CIG and 0.093 μm in UVAIG; (2) increasing of the critical depth of cut in UVAIG is likely owing to the lower grinding force in UVAIG than that in CIG; and (3) the ultrasonic vibration acted on the axis of the grinding wheel helps in the removal of material on the work-surface, but decreases the grinding energy in the ductile-brittle transition. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the predictive factors of therapeutic efficacy for chronic subdural hematoma (CSDH) patients receiving atorvastatin combined with dexamethasone therapy by using clinical imaging characteristics in conjunction with computed tomography (CT) texture analysis (CTTA). Clinical imaging characteristics and CT texture parameters at admission were retrospectively investigated in 141 CSDH patients who received atorvastatin combined with dexamethasone therapy from June 2019 to December 2022. The patients were divided into a training set (n = 81) and a validation set (n = 60). Patients in the training data were divided into two groups based on the effectiveness of the treatment. Univariate and multivariate analyses were performed to assess the potential factors that could indicate the prognosis of CSDH patients in the training set. The receiver operating characteristic (ROC) curve was used to analyze the predictive efficacy of the significant factors in predicting the prognosis of CSDH patients and was validated using a validation set. The multivariate analysis showed that the hematoma density to brain parenchyma density ratio, singal min (minimum) and singal standard deviation of the pixel distribution histogram, and inhomogeneity were independent predictors for the prognosis of CSDH patients based on atorvastatin and dexamethasone therapy. The area under the ROC curve between the two groups was between 0.716 and 0.806. As determined by significant factors, the validation's accuracy range was 0.816 to 0.952. Clinical imaging characteristics in conjunction with CTTA could aid in distinguishing patients with CSDH who responded well to atorvastatin combined with dexamethasone. [ABSTRACT FROM AUTHOR]

Multi-pole arrangements in magnetorheological plane finishing technology have been investigated in this study. A method of combining the material removal mechanism of micro-points using the empirical Preston equation is proposed to establish a prediction model for surface flatness, and the new Semiconductor Equipment and Materials International (SEMI) standard has been used to evaluate workpiece surface flatness. Based on the model, the effects of process parameters (polishing time, speed ratio, translational amplitude, polishing gap, etc.) on the flatness of workpieces with different shapes are predicted through simulation, and the effects of multi-pole arrangements are explored. The results of the analysis indicate that with changes in process parameters, the extent of change in surface flatness differs based on the shape of the workpiece. After polishing, concave workpieces show the highest levels of surface flatness. From simulations of magnetic pole arrangements, it is also found that magnetic field generators with different magnetic pole arrangements can be used for workpieces with different shapes to improve their surface flatness. Experiments with a workpiece with its shape measured using a white light interferometer showed that the surface flatness improved from being 33.561 μm initially to 21.822 μm after polishing, thereby demonstrating the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Magnetorheological finishing, considered as a promising polishing technique that can finish a nano-level smooth surface and free of surface or subsurface damage, has been widely utilized in ultra-smooth polishing of hard-to-machine materials. However, there are still several practical weaknesses in magnetorheological finishing (MRF) applied for wafer surface polishing. In this study, a new method using MRF effect was proposed for wafer polishing. Concretely, porous foam was used as a storage carrier of MR slurry, and thus, MR slurry can be bounded in porous foam in the finishing process (cluster MR-porous foam polishing, CMRPP). In this paper, an experimental rig was constructed to achieve CMRPP mechanism, the processing principle and material removal process in CMRPP were analyzed, and CMRPP experiments were conducted to investigate the effects of porous foam on surface polishing. The results indicate the following: (1) The polishing forces in CMRPP were increased compared to that of a cluster MR polishing without porous foam (CMRP), and CMRPP can get a greater shear force than of CMRP at a same normal force; (2) CMRPP can well hinder the solid-liquid separation and sustain the stability of the slurry performance; (3) CMRPP achieved a higher volumetric removal rate than that of CMRP and improving of material removal efficiency; (4) CMRPP can effectively achieve a nano-level smooth surface compared to that of CMRP. [ABSTRACT FROM AUTHOR]