H-type reinforced concrete poles are nowadays widely used as an economical and cost-effective substitute for wooden poles in power transmission lines. Although these poles are frequently subjected to biaxial loading in real field application, their biaxial interaction curves yet await detailed investigation. The current study was aimed at developing the biaxial bending interaction curves for H-type utility poles considering the measurements stipulated by the relevant standards and codes. Towards this, two commonly used H-type electric poles (i.e., 9 and 12 m ones with a normal strength of 400 kgF) were constructed, cured, and loaded at angles of 0, 30, 60, and 90 degrees with respect to their minor principal axes. The experimental results were described in terms of load-displacement curves, developed strains, cracking pattern, failure modes, and biaxial loading interaction curve. The obtained interaction diagrams can be reliably used to estimate the loading capacity of electric poles under biaxial loading in real field applications.

In order to study self-starting characteristics for H-type wind turbine, firstly, the effect of low Reynolds number and large separated flow on aerodynamic characteristics of airfoil were analyzed in detail, then two H-type wind turbines with different aerodynamic configurations were tested in a low speed wind tunnel for collecting the static torques at different phase angles and time-rotating speed curves in starting process. Based on theoretical analysis and experimental data, the cause of self-stating problem of H-type wind turbine has been revealed. The aerodynamic profile parameters of the wind turbine are closely related to the dependency of starting on initial phase position, and the minimum static torque determines whether the wind turbine has potential to start from rest. The time-rotating speed curves exhibit two different starting behaviour features, determined by the minimum dynamic torque in driving force conversion stage. Unless both the minimum static torque and minimum dynamic torque in driving force conversion stage are greater than the friction torque, the self-starting of the wind turbine cannot be realized. The typical self-starting behavior characteristics is that the time-rotating speed curve includes four different stages of initial linear acceleration, plateau, rapid acceleration and stable equilibrium with the final tip speed ratio more than 1.

In this paper, we investigate special points in which poles of the Green’s function of the D3/D7 branes are skipping. The system that we consider is SU (N c) N=4 SYM theory coupled to N_f flavors N=2 hypermultplets. We fluctuate the scalar field and find that there is no such special values of frequency and momentum to skip the poles. This behavior is different than scalar field in the AdS black brane background.