Element failure probability of soil slope under consideration of random groundwater level

YesThe instability of soil slopes is directly related to both the shear parameters of the soil material and the groundwater, which usually causes some uncertainty. In this study, a novel method, the element failure probability method (EFP), is proposed to analyse the failure of soil slopes. Based on the upper bound theory, finite element discretization, and the stochastic programming theory, an upper bound stochastic programming model is established by simultaneously considering the randomness of shear parameters and groundwater level to analyse the reliability of slopes. The model is then solved by using the Monte-Carlo method based on the random shear parameters and groundwater levels. Finally, a formula is derived for the element failure probability (EFP) based on the safety factors and velocity fields of the upper bound method. The probability of a slope failure can be calculated by using the safety factor, and the distribution of failure regions in space can be determined by using the location information of the element. The proposed method is validated by using a classic example. This study has theoretical value for further research attempting to advance the application of plastic limit analysis to analyse slope reliability.National Natural Science Foundation of China (grant no. 51564026), the Research Foundation of Kunming University of Science and Technology (grant no. KKSY201904006) and the Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province (grant no. ZJRM-2018-Z-02)

Experimental and simulation study of ultrasonic elliptical vibration cutting SiCp/Al composites: chip formation and surface integrity study

SiCp/Al composites are considered as a typical difficult-to-machining material due to the presence of reinforcing particles in the matrix. As the aerospace and military industries demand high dimensional accuracy, high efficiency and low damage for SiCp/Al composites, traditional cutting (TC) methods are no longer sufficient. Ultrasonic elliptical vibration cutting (UEVC) is a cutting technique suitable for difficult-to-machining materials. Its intermittent cutting characteristics can reduce the cutting force, and when the tool cuts the workpiece at ultrasonic frequency, similar to a dynamic impact behavior of the tool on the workpiece with ultrasonic frequency, improve the machinability of the material. In this paper, a multiphase based simulation model is developed that integrates the relationship between three phases and the random distribution of particles. The cutting process of SiCp/Al composites under UEVC and TC is simulated and the removal mechanism of SiCp/Al composites under UEVC is analyzed. The effects of dynamic impact on the UEVC of composites were discussed in terms of chip formation, cutting force and surface morphology. Finally, the correctness of the simulation results was verified by the relevant cutting experiments. The results showed that the UEVC produced more continuous serrations, easier fracture of SiC particles and improved machining performance of SiCp/Al composites compared with the TC. The cutting forces were reduced by 26% and 23%, and the surface roughness was reduced by 19% and 28% at two cutting depths of 25 μm and 50 μm, respectively

Development and psychometrics of a new Emotion-focused Regulation Questionnaire in Chinese

Individuals' strategies of emotion regulation play an important role in maintaining their mental health. However, few multi-strategy measures considered rumination subtypes (brooding and reflection) and covered five emotion -focused strategies. Across four samples (total N = 2398), the current study developed a new Emotion-focused Regulation Questionnaire in Chinese to survey five emotion-focused strategies including two subtypes of rumination, resulting in a six-factor theoretical framework. Exploratory factor analysis of samples 2 and 3 demonstrated a replicable five-factor structure consisting of Distraction, Brooding, Cognitive Rethinking (an integration of reflection and reappraisal), Acceptance, and Expressive Suppression, which is also the best model supported by confirmatory factor analysis of sample 4. The new EfRQ demonstrated acceptable to good internal consistencies (0.726 <= Cronbach's alpha <= 0.869 and 0.735 <= Macdonald's omega <= 0.871), and moderate test-retest reliabilities with ICCs ranging from 0.531 to 0.668. The convergent, discriminant, and criterion validity of EfRQ was supported by its associations with a range of constructs. Multivariate hierarchical regression analyses demonstrated its incremental validity beyond existing ER-related measures. Thus, the EfRQ is a reliable and valid instrument that would be useful in research and clinical environment

Influence of thermal aging on AC leakage current in XLPE insulation

Cross-linked polyethylene (XLPE) has been widely used as cable insulation material because of its excellent dielectric properties, thermal stability and solvent resistance. To understand the influence of thermal aging on AC leakage current in XLPE insulation, all XLPE specimens were aged in oven in temperature range from 120 °C to 150 °C, and a series of tests were conducted on these XLPE specimens in different aging stages to measure the characteristic parameters, such as complex permittivity, leakage current and complex dielectric modulus. In the experiments, the effects of thermal aging, temperature and frequency on the AC leakage current in XLPE insulation were studied by analyzing complex dielectric constant and dielectric relaxation modulus spectrum, the change of relaxation peak and activation energy. It has been found that the active part of leakage current increases sharply with the increase of aging degree, and the test temperature and frequency have an influence on AC leakage current but the influence of test temperature is mainly reflected in the low frequency region. In addition, it has been shown by the experiments that the reactive part of leakage current exhibits a strong frequency dependent characteristic in the testing frequency range from 10-2 Hz to 105 Hz, but the influence of test temperature and thermal aging on it is relatively small

Modeling and analysis of the cutting temperature of titanium alloys for quasi-intermittent vibration assisted swing cutting

EVC has proven to be an effective means of machining difficult-to-process materials. QVASC inherits EVC's intermittent cutting and friction reversal advantages, eliminating EVC cutting residues and improving machining quality. In order to deeply understand the cutting mechanism of QVASC, it is necessary to understand the cutting heat generation and tool surface temperature distribution in the process of QVASC. In this paper, the kinematic and frictional characteristics of the QVASC machining process are analyzed, the heat generation and heat transfer model of QVASC machining process is established, and the cutting temperature prediction model considering the characteristics of QVASC machining is proposed. According to whether there is heat convection and frictional shear stress distribution between the tool and the environment, the heat flow distribution of the front surface of the tool is divided into four regions, and the heat flux of the tool is calculated respectively. On this basis, the tool temperature of QVASC is solved by using the heat balance equation in the form of the partial differential equation. Finally, a systematic comparison experiment was carried out, and the effects of cutting depth, cutting speed, tool swing frequency, and amplitude on cutting temperature were studied by single factor method. The results show that the average cutting temperature of QVASC is 10 % lower than that of OC, which verifies the advantage of QVASC in reducing cutting temperature. Under different cutting depth, cutting speed, tool swing frequency and amplitude, the change trend of theoretical and experimental cutting temperature is the same, and the average error between them is 9 %, 8 %, 10 % and 9 %, respectively, which is within the acceptable range, proving the validity of the theoretical model. This research contributes to a deep understanding of the cutting process of QVASC and effectively determines the optimal cutting parameters

FROM CUTTING TO CASTING: IMPACT AND INITIAL BARRIERS TO THE PONSETI METHOD OF CLUBFOOT TREATMENT IN CHINA

In 2005, a nationwide clubfoot treatment program focused on the Ponseti method -an effective, affordable and minimally-invasive method- was initiated in China. The purpose of this study was to evaluate and identify barriers to the program. A qualitative study (rapid ethnographic study) was conducted using semi-structured interviews of 44 physicians who attended four of the 10 Ponseti training workshops, focus groups with parents of children with clubfoot, and observation. Several barriers to the Ponseti method are quite unique due to China's size, socio-economics, culture, politics, and healthcare systems. The barriers were classified into seven themes: (i) physician education, (ii) caregiver compliance, (iii) culture, (iv) public awareness, (v) poverty, (vi) financial constraints for physicians/hospitals, and (vii) challenges of the treatment process. A number of suggestions that could be helpful in reducing or eliminating the effects of these barriers were also identified: (i) pamphlets explaining clubfoot and treatment for caregivers, (ii) directories of Ponseti providers, (iii) funding/financial support, and (iv) improving public awareness. The information from this study provides healthcare planners with knowledge to assist in meeting the needs of the population and continued implementation of effective and culturally appropriate awareness and treatment programs for clubfoot throughout China

Design of an online video edge detection device for bottle caps based on FPGA

An online video edge detection device for bottle caps is designed and implemented using OV7670 video module and FPGA based control unit. By Verilog language programming, the device realizes the menu type parametric setting of the external VGA display, and completes the Roberts edge detection of real-time video image, which improves the speed of image processing. By improving the detection algorithm, the noise is effectively suppressed, and clear and coherent edge images are derived. The design improves the working environment, and avoids the harm to human body

Removal Modeling and Experimental Verification of Magnetorheological Polishing Fused Silica Glass

Compared to conventional polishing methods, magnetorheological polishing has no subsurface damage and a has good polishing effect, which is suitable for fused silica glass surface processing. However, the existing magnetorheological polishing material removal model has low processing efficiency and uneven removal, which cannot realize the deterministic processing of parts. The material removal (MR) model of fused silica glass is established by convolving the dwell time with the material removal function. The residence time is Fourier transformed. The consequence of process variable such as machining time, workpiece rotational frequency, machining gap and X-direction deflection on the MR of workpiece interface are analyzed. Experiments verify the validity of the material removal model. The surface precision PV value of the workpiece surface under the optimal process parameters was decreased from 7.959 nm to 0.609 nm for machining. The experiment results indicate that the established MR model can be implemented as the deterministic MR of the optical surface and ameliorate the surface accuracy of the workpiece surface

A case report of laparoscopic surgery for Mayer-Rokitansky-Küster-Hauser syndrome with preservation of functional primordial uterus

Abstract Background In the past, the primary treatment for MRKH syndrome (Mayer-Rokitansky-Küster-Hauser syndrome) with a functional primordial uterus was surgical removal of the functional primordial uterus. In rare instances, the endometrium of the functional primordial uterus is well developed, and surgical preservation of the functional primordial uterus provides the possibility of preserving reproductive function for these patients. Case presentation A 14-year-old female was diagnosed with type I MRKH syndrome with a functional primordial uterus through physical examination and imaging investigations. We freed the functional primordial uterus through laparoscopic surgery and excised a portion of the lower myometrium to create an outlet at a lower uterine segment, which we then intermittently anastomosed to the tip of the artificial vagina. The patient recovered well after the surgery, and a re-examination showed no significant abnormalities. Conclusion We were successful in preserving the functional primordial uterus using laparoscopic surgery in a patient with MRKH syndrome and connecting it to an artificial vagina through reconstructive surgery to ensure unobstructed menstrual drainage and preserve the reproductive potential of the patient