무한 매질에서의 파전파 현상은 공학과 자연과학의 여러 분야에서 다양한 물리적 현상을 서술하는데 활용되고 있고, 이 문제에 대한 해를 얻기 위하여 해석적 방법 또는 수치적 방법이 개발되어 사용되고 있다. 이 문제에 대한 정확한 해를 얻기 위해서는 무한 영역으로의 에너지 방사를 정확히 고려해야 하고, 이를 위해 다양한 수치적 또는 역학적 모형 또는 경계조건이 개발되었다. 이 연구에서는 층상 waveguide에서의 scalar wave 또는 SH파 전파 문제에 적용할 수 있는 새로운 경계조건을 제안하고자 한다. 이를 위해 waveguide 의 수직방향으로 유한요소 이산화를 적용하여 얻은 SH파의 지배방정식을 변형하여 waveguide의 무한 영역의 영향을 나타내는 경계조건을 유도한다. 층상 waveguide에서의 SH파에 대한 고유모드의 직교성을 이용하여, 새로운 경계조건은 기존의 root-finding absorbing boundary condition와 동등함을 보이고, 이로부터 새로운 경계조건의 차수가 증가할수록 정확성이 증가하고, 또한 이산화된 수준에서도 안정함을 유도할 수 있다. 제안된 경계조건을 층상 waveguide에서의 파전파 문제에 적용하여 그 정확성과 안정성을 검증한다.

At present, an important research area is the search for materials that are compatible with CMOS technology and achieve a satisfactory response rate and modulation efficiency. A strong local field of graphene surface plasmon polariton (SPP) can increase the interaction between light and graphene, reduce device size, and facilitate the integration of materials with CMOS. In this study, we design a new modulator of SPP-based cycle branch graphene waveguide. The structure comprises a primary waveguide of graphene–LiNbO3–graphene, and a secondary cycle branch waveguide is etched on the surface of LiNbO3. Part of the incident light in the primary waveguide enters the secondary waveguide, thus leading to a phase difference with the primary waveguide as reflected at the end of the branch and interaction coupling to enhance output light intensity. Through feature analysis, we discover that the area of the secondary waveguide shows significant localized fields and SPPs. Moreover, the cycle branch graphene waveguide can realize gain compensation, reduce transmission loss, and increase transmission distance. Numerical simulations show that the minimum effective mode field area is about 0.0130l2, the gain coefficient is about 700 cm–1, and the quality factor can reach 150. The structure can realize the mode field limits of deep subwavelength and achieve a good comprehensive performance.

Bar type waveguides are frequently employed as a buffer rod between ultrasonic senor and hard-to-access object in many measurement applications. Difficulty in pulse echo measurements using a buffer rod is caused by spurious echoes due to reflection, mode conversion and interference within the buffer rod of finite size. These spurious echoes degrade the signal to noise ratio (SNR) because of their possible interference with desired target signals. A tapered buffer rod or rods with non-symmetrical cross sections were used before to reduce these unwanted spurious echoes. In this paper, we propose signal processing techniques to remove the spurious echo signals. Experiments were performed in order to examine the refocusing and recovering the initial input waveform in the long range propagation of ultrasonic waves in cylindrical waveguides. Two different time reversal processes (regular TR and reciprocal TR or inverse filtering) are tested and the experimental results were compared

In this paper, numerical simulations are performed for the drying process of potato chip in a microwave oven with multiple waveguides, with the purpose of enhancing the uniformity in temperature distribution. A simulation model is built and simulated using COMSOL Multiphysics software. The simulation model uses 5 different positions of waveguides to see whether it affects the heat distribution in the material. In order to know the final temperature result of the material after it comes out of the cavity on a moving conveyor belt, the average temperature values along the direction of the conveyor belt motion are calculated and plotted. From the results, the best waveguide position is determined to get the best temperature distribution in the potato chips.

This study investigates wave propagation characteristics when guided waves propagate in a waveguide surrounded by non-homogeneous media. Assuming that the medium consists of same size elements, the acoustic properties of each element were determined using SWFEM method. The boundary conditions of each element and the waveguide were determined by random number.

Many new radar techniques have appeared on the electronic scene in recent years, such as a variety of automatic computer processing. However, even with the advent of these sophisticated radar techniques, an old problem continues to plague all radars: the problem of transmission line losses. With the higher performance required today, the Waveguide testing and trouble-shooting techniques remain essentially unchanged in principle. This paper dealt with the rf pulse "Time-domain Reflectometry" to inspect radar wave-guide system and compared with the conventional methods. During the investigation, it was verified that the pulsed TDR for wave-guide is superior to the conventional methods; 1. Disassembling is not needed to locate the discontinity points and measure the reflections of trobled points. 2. The results of the data are more precise. 3. The condition of individual component is able to the photographed and recorded permanently. 4. Since rf pulse TDR is based on the well-known basic radar principle, such a test set requires the minimum of training to operate. With the level of transmission line problems, the prospect of increasing complexity of equipment, and no relief in sight, the benifits must be emphasizied to adopt such a testing procedure.procedure.