We propose a design of a dielectric (silicon nitride) optical leaky wave antenna (OLWA) with periodic semiconductor (silicon) corrugations, capable of producing narrow beam radiation. The optical antenna radiates a narrow beam because a leaky wave (LW) with low attenuation constant is excited at one end of the corrugated dielectric waveguide. We show that pointing angle, beam-width, and operati...

background: in diagnostic radiology lead apron, are usually used to protect patients and radiology staff against ionizing radiation. lead apron is a desirable shield due to high absorption and effective attenuation of x-ray photons in the diagnostic radiology range. objective: although lead aprons have good radiation protection properties, in recent years, researchers have been looking for alte...

The melting process during laser powder bed fusion (LPBF) is accompanied by complex physical phenomena, which can be rarely scaled with acceptable effort to utilize the in component design obtain tailored mechanical properties adequate machine productivity. A constitutive law relating melt pool geometry parameters thereby plays an essential role practically fostering productivity and quality LP...

Siemens Healthcare, Knoxville, TN, USA A new positron annihilation imaging modality is described that enables nondestructive measurement of the linear attenuation coefficients (LACs) of positron beams in heterogeneous materials. This positron attenuation tomography (PAT) technique utilizes a positron emission tomography (PET) system embedded within a uniform static magnetic field, such as is fo...

The shielding calculations of bulk shielding for Advanced Proton Therapy Facility (APTRON) which is under design in Shanghai were carried out. The thickness of radiation shielding walls for the accelerator and treatment rooms of APTRON were determined by Monte Carlo simulation and empirical methods [1~3]. Assumptions of beam loss scenarios and workloads of different energy at LINAC, synchrotron...

A cone beam circular half-scan scheme is becoming an attractive imaging method in cone beam CT since it improves the temporal resolution. Traditionally, the redundant data in the circular half-scan range is weighted by a central scanning plane-dependent weighting function; FDK algorithm is then applied on the weighted projection data for reconstruction. However, this scheme still suffers the at...

Abstract Cone-beam computed tomography (CT) with circular scanning trajectory is known to suffer from so called cone-beam artifacts. Cone-beam artifacts are errors in the reconstructed volume due to incomplete radon data. These artifacts increase with increasing distance of the reconstructed plane from the midplane, i.e. the plane containing the X-ray source. Theoretically, the midplane represe...

Abstract In order to solve the problems of difficult measurement, inaccurate results and serious interference diffusion attenuation in nondestructive evaluation grain size magnesium alloy components with complex profile, sound field models plane, cylindrical conical parts based on multiple Gaussian beam method are studied, mechanism ultrasonic propagation medium curved test blocks analyzed, An ...