Two dimensional semiconductors with possible high room temperature mobility

We calculated the longitudinal acoustic phonon limited electron mobility of 14 two dimensional semiconductors with composition of MX$_2$, where M (= Mo, W, Sn, Hf, Zr and Pt) is the transition metal, and X is S, Se and Te. We treated the scattering matrix by deformation potential approximation. We found that out of the 14 compounds, MoTe$_2$, HfSe$_2$ and HfTe$_2$, are promising regarding to the possible high mobility and finite band gap. The phonon limited mobility can be above 2500 cm$^2$V$^{-1}$s$^{-1}$ at room temperature

Supply Chain Management of Fresh Produce: Melons in Western China

The western part of China has a long history and reputation of growing a variety of quality melons largely due to its semi arid agronomic environment. In the past decade, the industry suffered from the interrelated issues of unreliable quality and intense price competition. Even though both the government and supply chain stakeholders are aware of the problems, there is a need to look at the issues from a supply chain perspective and new ways of managing the melon supply chains are to be explored. This paper analysed the melon supply chain in western China in the areas of logistical efficiency and supply chain relationship management. The results of the analysis offer insights for improving the efficiency of the melon supply chain and the competitiveness the industry. The results also shed lights for other supply chains of fresh produce in developing countries in general.melon, China, supply chain, value chain, Crop Production/Industries, Industrial Organization, O13, O5, Q13,

High-efficiency and positivity-preserving stabilized SAV methods for gradient flows

The scalar auxiliary variable (SAV)-type methods are very popular techniques for solving various nonlinear dissipative systems. Compared to the semi-implicit method, the baseline SAV method can keep a modified energy dissipation law but doubles the computational cost. The general SAV approach does not add additional computation but needs to solve a semi-implicit solution in advance, which may potentially compromise the accuracy and stability. In this paper, we construct a novel first- and second-order unconditional energy stable and positivity-preserving stabilized SAV (PS-SAV) schemes for $L^2$ and $H^{-1}$ gradient flows. The constructed schemes can reduce nearly half computational cost of the baseline SAV method and preserve its accuracy and stability simultaneously. Meanwhile, the introduced auxiliary variable is always positive while the baseline SAV cannot guarantee this positivity-preserving property. Unconditionally energy dissipation laws are derived for the proposed numerical schemes. We also establish a rigorous error analysis of the first-order scheme for the Allen-Cahn type equation in $l^{\infty}(0,T; H^1(\Omega) )$ norm. In addition we propose an energy optimization technique to optimize the modified energy close to the original energy. Several interesting numerical examples are presented to demonstrate the accuracy and effectiveness of the proposed methods

Reliability Research of Power Distribution System For Important Units at the Airfield

Important power units at the airport are the direct units of aviation security, the reliability of power supply and distribution system directly affect the safety of it for aviation security. This paper analyzes the important units of electricity power supply system into the units of reliability. The basic reliability model and the mission reliability model are constructed respectively and the corresponding reliabilities are calculated. Then the paper studies on the relationship between two kinds of reliability as well as the influence on the reliability of power supply and distribution system, providing theoretical basis of planning, equipment selection, engineering design, reliable operation and maintenance management for important units of power supply system

Comparing the reduction of poverty rate between China and Gabon through One Belt and Road Project

The value of economic development and reduction of poverty has been at the forefront of research in many countries. However, little is thought about both China-Gabon. Data were collected employing a survey questionnaire approach to a sample of 210 financial sectors in China and Gabon. The results regarding Gabon show that governance reform can bring significant macro-financial benefits. Additionally, the results proposed that financial development significantly influence poverty reduction. Similarly, the results regarding china show development of the monetary sector significantly and positively impact poverty reduction during which, has been implemented for many years long term. This paper seeks to analyze causality between Gabon. There's an urgent need to enhance administration curb corruption order to increase domestic income, strengthen public management quality expenditure, business environment, promote investment both private sector