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Economic textbooks relate the principle of comparative advantage using examples of two products and two countries, the 2x2 case. We shall suggest an approach describing any finite number of products m and countries n, th...

Good air tightness of filter membranes is necessary for opening excavation chamber under high pressure. To improve the value of air tightness, one should understand the pore structure and permeability change of filter me...

Advanced geological prediction is one essential part in tunnel construction, and 3D E-SCAN resistivity device is introduced. In this device, the current and measuring electrodes are arranged on the tunnel face, which can...