我正在尝试安装ionic-cordova应用程序，并在运行bower install时显示以下错误。使用npm config delete proxy和.bowerrc文件中的bower删除了npm中的代理设置。没有错，为什么会发生这种情况
bower retry Request to http://bower.herokuapp.com/packages/ionic failed with ESOCKETTIMEDOUT, retrying in 2.0s
bower retry Request to http://bower.herokuapp.com/packages/ydn.db failed with ESOCKETTIMEDOUT, retrying in 1.1s
bower retry Request to http://bower.herokuapp.com/packages/ngCordova failed with ESOCKETTIMEDOUT, retrying in 1.2s
bower retry Request to http://bower.herokuapp.com/packages/angular-mocks failed with ESOCKETTIMEDOUT, retrying in 1.8s
bower retry Request to http://bower.herokuapp.com/packages/angular-md5 failed with ESOCKETTIMEDOUT, retrying in 1.9s
bower retry Request to http://bower.herokuapp.com/packages/angular-translate failed with ESOCKETTIMEDOUT, retrying in 1.2s
bower retry Request to http://bower.herokuapp.com/packages/angular-translate-loader-partial failed with ESOCKETTIMEDOUT, retrying in 2.0s
bower retry Request to http://bower.herokuapp.com/packages/angular-aria failed with ESOCKETTIMEDOUT, retrying in 1.7s
bower retry Request to http://bower.herokuapp.com/packages/moment failed with ESOCKETTIMEDOUT, retrying in 1.5s
bower retry Request to http://bower.herokuapp.com/packages/jszip failed with ESOCKETTIMEDOUT, retrying in 1.1s
bower retry Request to http://bower.herokuapp.com/packages/oclazyload failed with ESOCKETTIMEDOUT, retrying in 1.1s
bower retry Request to http://bower.herokuapp.com/packages/ckeditor failed with ESOCKETTIMEDOUT, retrying in 1.2s
bower retry Request to http://bower.herokuapp.com/packages/angular-ckeditor failed with ESOCKETTIMEDOUT, retrying in 1.9s
bower retry Request to http://bower.herokuapp.com/packages/angular-messages failed with ESOCKETTIMEDOUT, retrying in 2.0s