On a bounded strictly pseudoconvex domain in $\Bbb{C}^n$, $n>1$, the smoothness of Cheng-Yau solution to Fefferman's complex Monge-Ampere equation up boundary is obstructed by local curvature invariant boundary. For domains $\Bbb{C}^2$ which are diffeomorphic ball, we motivate and consider problem determining whether global vanishing this obstruction implies biholomorphic equivalence unit ball....

In this paper, we consider the reconstruction problem of photoacoustic tomography (PAT) with a flat observation surface. We develop a direct reconstruction method that employs regularization with wavelet sparsity constraints. To that end, we derive a wavelet-vaguelette decomposition (WVD) for the PAT forward operator and a corresponding explicit reconstruction formula in the case of exact data....

Nowadays, concrete with strength higher than 50 MPa is utilized due to the ever increasing need for higher strength and prolonged healing properties. Despite the widespread use of high-strength concrete, only a few research projects have been conducted on the punching shear strength of high-strength concrete slabs. Reinforced concrete flat slabs are widely employed in structural systems. The lo...

machines using ball end mill cutters; the determination of the optimum tool and the minimization of the machining times for each surface. In the proposed methodology, the accessibility problem is first analyzed and then the optimal tool is selected from a database of tools. Next, and depending on the machining method, we select automatically the optimum sweeping method and the associated machin...

Camera calibration is a critical problem in computer vision. This paper presents a new method for extrinsic parameters computation: images of a ball rolling on a flat plane in front of the camera are used to compute roll and pitch angles. The calibration is achieved by an iterative Inverse Perspective Mapping (IPM) process that uses an estimation on ball gradient invariant as a stop condition. ...

[Purpose] This study examined the effects of a ball-backrest chair combined with an accelerometer on the pain and trunk muscle endurance of a computer worker with low-back pain (LBP). [Subject and Methods] A 36-year-old male with a flat back who complained of LBP at the L3-5 level was the subject. He used the ball-backrest chair when working at a computer for 1 week. [Results] After using the b...

The standard cosmological model posits a spatially flat universe of infinite extent. However, no observation, even in principle, could verify that the matter extends to infinity. In this work we model the universe as a finite spherical ball of dust and dark energy, and obtain a lower limit estimate of its mass and present size: the mass is at least 5× 10M⊙ and the present radius is at least 50 ...