introduction: the aim of this study was to evaluate the composite surface treated by different powers of erbium-doped yttrium aluminum garnet (er:yag) laser in comparison with bur preparation via scanning electron microscope. methods: fourteen composite resin blocks with 15× 10 × 10 mm dimensions were used in this study. the samples were divided to seven groups as follow: group 1 (power: 1 w, e...

purpose: to evaluate the correlation between corneal power and corneal horizontal white to white diameter in myopic patients scheduled for lasik surgery. methods: overall, in 840 eyes of 420 myopic subjects scheduled for lasik, horizontal white to white diameter and mean corneal power were obtained using orbscan ii. pearson correlation test and regression analysis were used to detect any correl...

this paper presents a control strategy for fuel cell/energy storage power generation system during voltage sag conditions. the hybrid dc power sources are connected to grid using power electronic converters include dc-dc converter and grid connected voltage source inverter. the power from hybrid power sources is controlled during voltage sag by designing of control strategy for dc-dc converter....

The terms of Power, influence and authority could be heard in political world vastly, but using these terms is not leaving only to this realm. Despite its visual simplicity, generally there is not similar and equal perception about term of Power among people. Understanding about by politicians differs from lawyer perception about this term.  What people takes about Power, totally differ from wh...

the present study aimed to answer the question that qajar government as a political system was an authoritarian government? this study deals with the outcomes of qajar authoritarianism and the impact of effective historical-geographical conditions of iran on emergence or continuance of authoritarianism. authoritarianism in this study is not a one-dimensional structure and it is composed of some...

In this paper we define a new type of rings ”almost powerhermitian rings” (a generalization of almost hermitian rings) and establish several sufficient conditions over a ring R such that, every regular matrix admits a diagonal power-reduction.

as renewable energy increasingly penetrates into power grid systems, new challenges arise for system operators to keep the systems reliable under uncertain circumstances, while ensuring high utilization of renewable energy. this paper presents unit commitment (uc) which takes into account the volatility of wind power generation. the uc problem is solved with the forecasted intermittent wind pow...

in this paper, a novel control method for photovoltaic converter connection to the national gridis presented, so in addition to the injection control by solar arrays to the grid, this method cancompensate reactive power and harmonics in the load current. the system will be connected inparallel between the grid and load. the proposed system supplies all load power consumption(including active po...