Self-gravitational force calculation for infinitesimally thin disks is important for studies on the evolution of galactic and protoplanetary disks. Although high-order methods have been developed for hydrodynamic and magneto-hydrodynamic equations, high-order improvement is desirable for solving self-gravitational forces for thin disks. In this work, we present a new numerical algorithm that is of linear complexity and of high-order accuracy. This approach is fast since the force calculation is associated with a convolution form, and the fast calculation can be achieved using Fast Fourier Transform. The nice properties, such as the finite supports and smoothness, of B-splines are exploited to stably interpolate a surface density and achieve a high-order accuracy in forces. Moreover, if the mass distribution of interest is exclusively confined within a calculation domain, the method does not require artificial boundary values to be specified before the force calculation. To validate the proposed algorithm, a series of numerical tests, ranging from 1st-to 3rd-order implementations, are performed and the results are compared with analytic expressions derived for 3rd-and 4th-order generalized Maclaurin disks. We conclude that the improvement on the numerical accuracy is significant with the order of the method, with only little increase of the complexity of the method.

Engineering cost index is one of the core tools to reflect the change of supply and demand in construction market and the level of productivity development. This paper comprehensively analyzes the actuality of compilation and application of engineering cost index from some representative provinces and cities in China, and systematically introduces and contrasts the application of engineering cost index in developed and developing countries or regions, providing reference for the engineering cost index during the transition to market economy in our country in the transition period, making it the edge tool to control engineering cost in a reasonable way.

In high current applications that use several parallel-connected SiC MOSFETs (e.g., automotive traction inverters), optimal current sharing is integral to overall system reliability. Threshold voltage (VTH) variation in SiC MOSFETs is a prevalent reliability issue that can cause current mismatch in parallel-connected devices. Using experimental measurements and compact modelling, a technique has been developed for characterising the impact of VTH variation in up to 8 parallel-connected SiC MOSFETs. This model can predict the allowable VTH variation for optimal current sharing. It can also be used to evaluate the impact of other parameters, including gate driver synchronisation, on current sharing in parallel devices.

With the popularization of electronic communication and social media, people-related information data has increased massively, which brings about a series of "privacy data risks" such as information data leakage. Conducting the personal behavior data as the index, the application domain as the criterion layer, and the personal privacy price as the goal, the personal privacy pricing model is established based on the analytic hierarchy process. Then we get the revised model of private pricing by combing the privacy valuation function and the market supply and demand relationship. Taking brand, quality, strategic factors into consideration, we establish the group privacy pricing system, national privacy pricing model.