The multicriteria ABC inventory classification has been widely adopted by organizations for the purpose of specifying, monitoring, and controlling inventory efficiently. It categorizes the items into three groups based on some certain criteria, such as inventory cost, part criticality, lead time, and commonality. There has been extensive research on such a problem, but few have considered that the judgments about criteria’s importance order usually exhibit a substantial degree of variability. In light of this, we propose a new methodology for handling the multicriteria ABC inventory classification problem using the social choice theory. Specifically, the pessimistic and optimistic results for all possible individual judgments are obtained in a closed-form manner, which are then balanced by the Hurwicz criterion with a “coefficient of optimism”. The CRITIC (Criteria Importance Through Intercriteria Correlation) method is used to aggregate the individual judgments into a collective choice, according to which the items are classified into Groups A, B, and C. Through a numerical experiment, we show that the proposed methodology not only considers all possible preferences among the criteria, but also generates flexible classification schemes.

Species diversity is a crucial index used to evaluate the stability and complexity of forest ecosystems. Studying the relationship between stand structure and understory herbaceous plants species diversity is useful for managers to formulate the best forest structure optimization method with the goal of improving herbaceous species diversity. In this research, Platycladus orientalis plantations in Beijing were taken as the research object. Pearson’s correlation analysis was used to explore the single-factor correlation between stand structure and understory herbaceous plants species diversity; furthermore, a typical correlation analysis and multiple linear regression were used to explore the multi-factor correlation and analyze the dominant stand structure parameters affecting understory herbaceous plants species diversity. In the range of stand structures studied, the results showed that canopy density was negatively correlated with the Shannon–Wiener index and Simpson index (p < 0.01), and tree density was negatively correlated with the Shannon–Wiener index (p < 0.05). In terms of stand spatial structure, the mingling degree was positively correlated with the Shannon–Wiener index, Simpson index, Margalef richness index and Pielou evenness index (p < 0.05), while the uniform angle was negatively correlated with the Pielou evenness index (p < 0.05). The correlation coefficient of the first group of typical variables in the typical correlation analysis was 0.90 (p < 0.05); from this group of typical variables, it can be concluded that canopy density is the most influential indicator affecting the comprehensive index of understory herbaceous plants species diversity, with a load of −0.690, and the Shannon–Wiener index and Simpson index are the most responsive indicators of changes in the comprehensive index of stand structure, with loads of 0.871 and 0.801, respectively. In the process of the management of Platycladus orientalis plantations under a low altitude, south slope, thin soil layer and hard soil parent material, in order to improve the herbaceous species diversity, the canopy density of the overstory and tree density should be appropriately reduced. Additionally, it is necessary to regulate the horizontal spatial structure of stands. When the trees are randomly distributed and the mingling degree is high, the species diversity of herbs can be increased.

In the background of the development of global low-carbon economy, to blossom the low-carbon transport is necessary for every country. Railway is recognized as a green transport with low-power consumption, less pollution, which is one of the most important infrastructures developed actively around the world. With the approaching era of high-speed railway, railway passenger demand has been paid much more attention. As passengers with different trip purposes are influenced by different factors when choosing means of transport, this paper will classify passengers by trip purposes and find the main influential factors according to different types of passengers with the aid of rough set. Then put forward initiatives aimed at improving passenger satisfaction, and enhance the positive attitude of passengers towards rail transportation.

The proton sensor is an important part of the proton magnetometer, which is mainly responsible for generating a polarizing magnetic field and receiving induced signals. This paper presents the design scheme of the proton sensor, including the selection of the internal coil structure of the sensor, the selection of the internal solution, and the design of the sensor shielding layer. Then introduces the proton sensor of the Canadian GSM-19T proton magnetometer, which is one of the world’s leading proton magnetometers. And the performance of the two sensors is compared and analyzed by designing sensor performance test experiment. The experimental results show that the initial amplitude of the test signal of the proton sensor is 2.2V, and the signal decay time constant is 0.86s, the performance is similar to that of the Canadian proton sensor.

Let K/k be a finite Galois extension of number fields, and let H K be the Hilbert class field of K. We find a way to verify the nonsplitting of the short exact sequenceby finite calculation. Our method is based on the study of the principal version of the Chebotarev density theorem, which represents the density of the prime ideals of k that factor into the product of principal prime ideals in K. We also find explicit equations to express the principal density in terms of the invariants of K/k. In particular, we prove that the group structure of the ideal class group of K can be determined by reading the principal densities.