移相法实现单边带信号的调制

本文单边带（ＳＳＢ）信号的２种产生方法，即滤波法和移相法。重点对移相法的产生ＳＳＢ信号的方法作了祥细的讨论并给出了具体的电路，这种产生ＳＳＢ信号的方法具有载波法抑制比低、低成本、不需要滤波器，对相位误差和增益误差要求不高等突出特点。     

Viewpoint: Soda taxes – Four questions economists need to address

The popularity of soda taxes as a public health policy has grown rapidly in the last few years. While the evidence that the tax works in reducing the purchases of soda is emerging, there are a number of questions that are yet to be answered before the broader effectiveness of this measure can be determined. Beyond health effects, there is more specifically a need to better understand the economic mechanisms of change, redistributive effects, as well as causal and spillover effects in food systems and economy more broadly.     

Universal Pareto dominance and welfare for plausible utility functions

We study Pareto efficiency in a setting that involves two kinds of uncertainty: Uncertainty over the possible outcomes is modeled using lotteries whereas uncertainty over the agents’ preferences over lotteries is modeled using sets of plausible utility functions. A lottery is universally Pareto undominated if there is no other lottery that Pareto dominates it for all plausible utility functions. We show that, under fairly general conditions, a lottery is universally Pareto undominated iff it is Pareto efficient for some vector of plausible utility functions, which in turn is equivalent to affine welfare maximization for this vector. In contrast to previous work on linear utility functions, we use the significantly more general framework of skew-symmetric bilinear (SSB) utility functions as introduced by Fishburn (1982). Our main theorem generalizes a theorem by Carroll (2010) and implies the ordinal efficiency welfare theorem. We discuss three natural classes of plausible utility functions, which lead to three notions of ordinal efficiency, including stochastic dominance efficiency, and conclude with a detailed investigation of the geometric and computational properties of these notions.