航空发动机空中起动供油特性分析

本文研究航空发动机空中因富油问题导致起动困难,在分析起动供油的基础上,设计了高空修正模块来补偿飞行高度对供油特性的影响。并通过模拟试验进行了比较和分析。结果表明方案可行,能够解决发动机空中起动时的富油状态问题。     

New evidence on sources of macroeconomic fluctuations in sub-Saharan African countries

Following a global vector autoregressive (GVAR) approach, this paper presents new evidence on the validity of international transmission of economic shocks from key trading partners as sources of macroeconomic fluctuations in sub-Saharan African (SSA) countries. The GVAR model was estimated for 21 SSA countries grouped into three country classes—oil-rich, other-resources-rich and non-resource-based economies, to account for output shocks from crucial trading partner countries—United States, United Kingdom, China and Europe. Furthermore, the generalized forecast error variance decompositions results reveal that output shocks from key trading partners constitute significant contributors to changes in key macroeconomic indicators—real gross domestic product, inflation, exchange rate and short-term interest rate, in the SSA region. The generalized impulse response functions indicate that these economic shocks have more significant impacts on oil-rich countries than on other country groups. A key recommendation from this study is that SSA countries, especially the resource-rich economies, need to strengthen and diversify their economic structure, including the trade basket.