含盐遗址重塑土的吸力测定及土水特征曲线拟合

Under the long-term impacts of influencing factors including water and soluble salts, the Site of Yarkhoto Ancient City which is a precious earthen heritage is subjected to irreversible deterioration. Exfoliation of surface crusts on the remaining walls is one of the commonly observed pathologies. The behaviors of unsaturated soils are dependent on suction, thus making it crucial to obtain reliable soil-water retention curve (SWRC) for investigating the deterioration mechanisms of earthen heritages. The slurries with different NaCl contents are prepared from the local soils. The total suction and matric suction during desiccation are determined using five methods (vapor equilibrium, water potentiometer, filter paper, pressure plate and high-capacity tensiometer), and the discrepancies are further discussed. Meanwhile, two models, i.e., van Genuchten (vG) and Fredlund & Xing (FX), are adopted to model the SWRC. The results show that NaCl has insignificant effect on the matric suction but induces osmotic suction, leading to a great increase in the total suction especially at high water contents. The general trend of water retention behavior of soils obtained by various methods is consistent. Based on the data obtained by different methods, the errors of curve fitting can be minimized, and a reliable SWRC on drying path is acquired in the full suction range. Both vG and FX models can model the experimental data well, which provides a scientific basis for further quantitative analysis of the evolution process of surface crusts cracking in earthen heritages

8-Methyl-5-methyl­ene-2-oxotricyclo[5.3.1.13,9]dodecan-endo-8-ol

The title compound, C14H20O2, crystallizes with homochiral chains of mol­ecules hydrogen bonded together along the b axis. Adjacent chains in the ab plane contain mol­ecules of the same chirality, leading to a chiral segregation of the mol­ecules into layers

Parameter Selection and Uncertainty Measurement for Variable Precision Probabilistic Rough Set

In this paper, we consider the problem of parameter selection and uncertainty measurement for a variable precision probabilistic rough set. Firstly, within the framework of the variable precision probabilistic rough set model, the relative discernibility of a variable precision rough set in probabilistic approximation space is discussed, and the conditions that make precision parameters α discernible in a variable precision probabilistic rough set are put forward. Concurrently, we consider the lack of predictability of precision parameters in a variable precision probabilistic rough set, and we propose a systematic threshold selection method based on relative discernibility of sets, using the concept of relative discernibility in probabilistic approximation space. Furthermore, a numerical example is applied to test the validity of the proposed method in this paper. Secondly, we discuss the problem of uncertainty measurement for the variable precision probabilistic rough set. The concept of classical fuzzy entropy is introduced into probabilistic approximation space, and the uncertain information that comes from approximation space and the approximated objects is fully considered. Then, an axiomatic approach is established for uncertainty measurement in a variable precision probabilistic rough set, and several related interesting properties are also discussed. Thirdly, we study the attribute reduction for the variable precision probabilistic rough set. The definition of reduction and its characteristic theorems are given for the variable precision probabilistic rough set. The main contribution of this paper is twofold. One is to propose a method of parameter selection for a variable precision probabilistic rough set. Another is to present a new approach to measurement uncertainty and the method of attribute reduction for a variable precision probabilistic rough set

Detection of low-dimensional chaos in drill bit torsional vibration time series

The near-bit strap-down measurement-while-drilling (MWD) system has been developed in this paper. By means of triaxial magnetometers, calculation method for bit rotational velocity was developed to monitor the drill bit torsional vibration. A number of techniques were applied to perform a nonlinear analysis of the experimental data of torsional vibration. Estimate delay time with mutual information and calculated the embedding dimension through Cao’s method, after reconstruct the phase space, the chaotic characteristics of the system were analyzed by calculating the correlation dimension and the largest Lyapunov exponent. We show that the largest Lyapunov exponent is positive and the correlation dimension is more than two, which is a strong indicator for the chaotic behaviour of the system. We also found that chaotic characteristics of the drill bit torsional vibration even existed in the whole drilling process, and thus the techniques based on phase space dynamics can be used to analyze and to predict drill bit torsional vibration. The results of this paper are of interest to applied and theoretical mechanics and petroleum engineering

Towards universal health coverage: achievements and challenges of 10 years of healthcare reform in China.

Universal health coverage (UHC) has been identified as a priority for the global health agenda. In 2009, the Chinese government launched a new round of healthcare reform towards UHC, aiming to provide universal coverage of basic healthcare by the end of 2020. We conducted a secondary data analysis and combined it with a literature review, analysing the overview of UHC in China with regard to financial protection, coverage of health services and the reported coverage of the WHO and the World Bank UHC indicators. The results include the following: out-of-pocket expenditures as a percentage of current health expenditures in China have dropped dramatically from 60.13% in 2000 to 35.91% in 2016; the health insurance coverage of the total population jumped from 22.1% in 2003 to 95.1% in 2013; the average life expectancy increased from 72.0 to 76.4, maternal mortality dropped from 59 to 29 per 100 000 live births, the under-5 mortality rate dropped from 36.8 to 9.3 per 1000 live births, and neonatal mortality dropped from 21.4 to 4.7 per 1000 live births between 2000 and 2017; and so on. Our findings show that while China appears to be well on the path to UHC, there are identifiable gaps in service quality and a requirement for ongoing strengthening of financial protections. Some of the key challenges remain to be faced, such as the fragmented and inequitable health delivery system, and the increasing demand for high-quality and value-based service delivery. Given that China has committed to achieving UHC and 'Healthy China 2030', the evidence from this study can be suggestive of furthering on in the UHC journey and taking the policy steps necessary to secure change

Towards universal health coverage: lessons from 10 years of healthcare reform in China.

Universal health coverage (UHC) is driving the global health agenda. Many countries have embarked on national policy reforms towards this goal, including China. In 2009, the Chinese government launched a new round of healthcare reform towards UHC, aiming to provide universal coverage of basic healthcare by the end of 2020. The year of 2019 marks the 10th anniversary of China's most recent healthcare reform. Sharing China's experience is especially timely for other countries pursuing reforms to achieve UHC. This study describes the social, economic and health context in China, and then reviews the overall progress of healthcare reform (1949 to present), with a focus on the most recent (2009) round of healthcare reform. The study comprehensively analyses key reform initiatives and major achievements according to four aspects: health insurance system, drug supply and security system, medical service system and public health service system. Lessons learnt from China may have important implications for other nations, including continued political support, increased health financing and a strong primary healthcare system as basis

Detection of low-dimensional chaos in drill bit torsional vibration time series

The near-bit strap-down measurement-while-drilling (MWD) system has been developed in this paper. By means of triaxial magnetometers, calculation method for bit rotational velocity was developed to monitor the drill bit torsional vibration. A number of techniques were applied to perform a nonlinear analysis of the experimental data of torsional vibration. Estimate delay time with mutual information and calculated the embedding dimension through Cao’s method, after reconstruct the phase space, the chaotic characteristics of the system were analyzed by calculating the correlation dimension and the largest Lyapunov exponent. We show that the largest Lyapunov exponent is positive and the correlation dimension is more than two, which is a strong indicator for the chaotic behaviour of the system. We also found that chaotic characteristics of the drill bit torsional vibration even existed in the whole drilling process, and thus the techniques based on phase space dynamics can be used to analyze and to predict drill bit torsional vibration. The results of this paper are of interest to applied and theoretical mechanics and petroleum engineering

Rapid FRD determination for multiplexed fibre systems -- I. The quasi-near field model and its uncertainties

Focal Ratio Degradation (FRD) in fibres is a crucial factor to control in astronomical instruments in order to minimize light loss. As astronomical instrumentation has advanced, the integration of large populations of fibres has become common. However, determining FRD in multiplexed fibre systems has become a challenging and time-consuming task. The Integral Field Unit for the Fiber Arrayed Solar Optical Telescope (FASOT-IFU) represents the most densely arranged fibre-based IFU in a single unit. Due to the close packing of fibres in the V-groove of the slit end, measuring FRD is particularly challenging as the output spots are prone to overlapping with adjacent fibres. In this paper, a novel method based on the quasi-near field model is proposed to enable rapid FRD measurement in highly multiplexed fibre systems like IFUs and multi-object observation systems. The principle and uncertainties associated with the method are investigated. The method's validity is demonstrated by applying it to determine the FRD in FASOT-IFU, with the achieved FRD performance meeting the acceptable requirements of FASOT-IFU, where the output focal ratio primarily falls within the range of 5.0-7.0. The results indicate that the proposed method offers several advantages, including the simultaneous and rapid measurement of FRD in multiple fibres with high accuracy (error smaller than 0.35 in F-ratio). Furthermore, besides FRD, the method exhibits potential for extensive measurements of throughput, scrambling, and spectral analysis.Comment: 10 pages, 12 figures, submitted to MNRA