用反射波法进行桩基无损检测

桩基础质量的检测是保证基础工程安全的重要措施。针对传统的检测方法静荷载试验法和钻孔取芯法存在的设备笨重、成本高、工期长和检测数量少的缺点 ,提出了用反射波法进行桩基无损检测 ,该法较传统的检测法具有成本低、效率高和可靠性高的特点。最后 ,将反射波法用于天津市红桥区工商行大厦砼钻孔灌注桩桩基的无损检测 ,结合实测的桩基速度波分析了检测到的桩基缺陷类型及判断原则。     

Are experienced people affected by a pre-set default option—Results from a field experiment

The objective of the present paper is to investigate the robustness of the well-known result that pre-set default options determine people's choices. We do so by conducting a field experiment among environmental economists attending a large international conference on environmental economics. The participants were, at the time of registration, randomly allocated to different treatments related to carbon offsetting. What differs from earlier default studies is that our subjects have good knowledge about the good at hand. We investigate whether the choices of these experienced individuals are affected by a pre-set default option, and we also study the effect of a treatment with no pre-set default option. Our results, together with previous findings, indicate that the effect of a default option attenuates with experience.