Dynamics Characteristics of Groundwater Exploitation in Tianjin, P.R. China

Abstract

We characterize observable sets for 1-dim Schrödinger equations in R: i∂ t u = (−∂ 2x + x 2m )u (with m ∈ N := {0, 1, . . . }). More precisely, we obtain what follows: First, when m = 0, E ⊂ R is an observable set at some time if and only if it is thick, namely, there is γ > 0 and L > 0 so thatSecond, when m = 1 (m ≥ 2 resp.), E is an observable set at some time (at any time resp. ) if and only if it is weakly thick, namelyFrom these, we see how potentials x 2m affect the observability (including the geometric structures of observable sets and the minimal observable time). Besides, we obtain several supplemental theorems for the above results, in particular, we find that a half line is an observable set at time T > 0 for the above equation with m = 1 if and only if T > π 2 .2010 Mathematics Subject Classification. 93B07, 35J10.

Experimental Study on the Relationship between Fatigue and Unsafe Behavior of Urban Rail Transit Drivers

“…Sun ( 31 ) made a clear distinction between unsafe behavior and human error, defining intentional misbehavior as unsafe behavior and unintentional negligence or forgetting as human error. According to Wang ( 32 ), there are similarities and differences between human unsafe behavior and human error: human unsafe behavior focuses on the behavior that causes accidents, while human error is focused on the mistakes of the behavior itself.…”

Machining Strategy and Experimental Study of Ultrasonic-Assisted Bidirectional Progressive Spiral Milling of Carbon Fiber Holes

“…The end cutting edge cuts continuously, and the processing form and insert milling are similar. At the same time, the calculation of the undeformed cutting parameters and material removal volume ratio of the milling cutter edge and the end cutting edge shows that, when the machining aperture and tool diameter are determined, the ratio of material volume of the peripheral edge and end cutting edge is constant and is not affected by the machining parameters [11]. Traditional spiral milling holes often adopt the cylindrical milling cutter, material removal is mostly conducted by the bottom edge, a weak blade is the main part that completes the processing of the hole wall [12,13], and the material removal in the process of the cutting tool's weak blade is the focus.…”