Founded in 2012, the National Joint Engineering Research Center of High Performance Metal Wear Resistant Materials Technology at Jinan University, one of the"211"key national universities in China, specializ...Founded in 2012, the National Joint Engineering Research Center of High Performance Metal Wear Resistant Materials Technology at Jinan University, one of the"211"key national universities in China, specializes in the research and development of iron based wear resistant materials and their casting technologies to provide support to the production process.展开更多
A theoretical and modulation study of a dipole antenna located in rectangular waveguide is presented. The aim is to determine the nature and dimensions which allow us to attain the simulations in free space. We compar...A theoretical and modulation study of a dipole antenna located in rectangular waveguide is presented. The aim is to determine the nature and dimensions which allow us to attain the simulations in free space. We compare the behavior of a dipole antenna modeled by MOM-GEC with those obtained in free space. A method of moment (MoM) approach combined to the generalized equivalent circuit (GEC) modeling is applied to compute the input impedance of a dipole antenna resonating at 1.8 GHz. A parametric study is conducted to investigate the wall effects on the antenna performances. Also we study the convergence of the input impedance as a function of test function number. The current values with integral method (MOM) are compared with the computed values obtained from numerical methods such as the combined MOM-GEC. The simulated values agree with values obtained from numerical methods.展开更多
In a previous work, we developed a consistent TAC (tissue attenuation coefficient) estimator using bubble echoes. Based on temporal averaging, we can improve the estimation precision of TAC for the tissue bounded betw...In a previous work, we developed a consistent TAC (tissue attenuation coefficient) estimator using bubble echoes. Based on temporal averaging, we can improve the estimation precision of TAC for the tissue bounded between two vessels. In this paper, we extend it to use frequency diversity for saving interrogation time by transmit multiple narrowband signals in each pulse. At first, we analyze the deterministic and stochastic properties of the diversity signals. Then a multi-band maximum likelihood diversity combiner is developed. We also provide diversity gains of different diversity estimators for comparing their estimation efficiencies. In the experimental work, we design a simplified phantom for demonstrating the performance of the purposed estimator. It is shown that the TAC estimation rate can be improved by frequency diversity. The convergence rates of single-band and multi-band estimators are compared and it is shown that the multi-band estimator is more consistent than the single-band estimator.展开更多
文摘Founded in 2012, the National Joint Engineering Research Center of High Performance Metal Wear Resistant Materials Technology at Jinan University, one of the"211"key national universities in China, specializes in the research and development of iron based wear resistant materials and their casting technologies to provide support to the production process.
文摘A theoretical and modulation study of a dipole antenna located in rectangular waveguide is presented. The aim is to determine the nature and dimensions which allow us to attain the simulations in free space. We compare the behavior of a dipole antenna modeled by MOM-GEC with those obtained in free space. A method of moment (MoM) approach combined to the generalized equivalent circuit (GEC) modeling is applied to compute the input impedance of a dipole antenna resonating at 1.8 GHz. A parametric study is conducted to investigate the wall effects on the antenna performances. Also we study the convergence of the input impedance as a function of test function number. The current values with integral method (MOM) are compared with the computed values obtained from numerical methods such as the combined MOM-GEC. The simulated values agree with values obtained from numerical methods.
文摘In a previous work, we developed a consistent TAC (tissue attenuation coefficient) estimator using bubble echoes. Based on temporal averaging, we can improve the estimation precision of TAC for the tissue bounded between two vessels. In this paper, we extend it to use frequency diversity for saving interrogation time by transmit multiple narrowband signals in each pulse. At first, we analyze the deterministic and stochastic properties of the diversity signals. Then a multi-band maximum likelihood diversity combiner is developed. We also provide diversity gains of different diversity estimators for comparing their estimation efficiencies. In the experimental work, we design a simplified phantom for demonstrating the performance of the purposed estimator. It is shown that the TAC estimation rate can be improved by frequency diversity. The convergence rates of single-band and multi-band estimators are compared and it is shown that the multi-band estimator is more consistent than the single-band estimator.
