New numerical radius inequalities for Hilbert space operators are given. These inequalities improve a well-known inequality of F. Kittaneh. We also show that the inequalities obtained here are sharp. A refinement of the triangle inequality is also shown.

中文翻译：

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Hilbert空间算子数值半径的新估计

给出了希尔伯特空间算子的新的数值半径不等式。这些不等式改善了F. Kittaneh的众所周知的不等式。我们还表明，这里获得的不平等现象非常明显。还显示了三角形不等式的细化。