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Space traveling wave tube (TWT) is one kind of microwave vacuum tube for communication, which must have high reliability, high power. The life of the space TWT is requested for a long lifetime of 10–15 years. In order to shorten the testing process, accelerated aging tests are performed at higher than normal operating temperature and currents of cathode. But in the process of the actual test, the...
In absence of the other navigation system, cruise missile INS error will be cumulated continuously with the increase of endurance. Therefore, this article proposes a novel practical INS error estimation and compensation method based on continuous observation to feature target. With the observation sequence and pseudo observation sequence, the residual error sequence is constructed. And the error estimation...
Space traveling wave tube (TWT) is one kind of microwave vacuum tube for communication, which must have high reliability, high power. The life of the space TWT is requested for a long lifetime of 10–15 years. In order to shorten the testing process, accelerated aging tests are performed at higher than normal operating temperature and currents of cathode. But in the process of the actual test, the...
On the basis of a binary stochastic differential game model representing the relationship between cartelized energy suppliers and a government on behalf of consumers, we study the decision-making behaviors of a government and suppliers with time-inconsistent preference in both cooperative and non-cooperative scenarios by making comparison with the benchmark model for game players with time-consistent...
Pulmonary nodules are potential manifestation of lung cancer. Accurate segmentation of juxta-vascular nodules and ground glass opacity (GGO) nodules are an important and active area of research in medical image processing. At present, the classical segmentation algorithm of pulmonary nodules can not accurately obtain the boundary information of pulmonary nodules. In order to solve the problem, a new...
A three-dimensional (3-D) large signal model of beam-wave interaction in a folded waveguide (FW) slow wave circuit is described. The 3-D code carries out with numerical solutions of the structure, without using the analytical formulations of the eigenmodes. This model can also be used in helix TWTs and coupled-cavity TWTs.
High-order algorithms of Particle-in-cell (PIC) method can reduce the numerical noises, increase the sizes of space grids, and reduce the CPU time. Four-order interpolation algorithms for charge conservation in PIC simulations are presented. The methods may be used for the case that a particle trajectory is a zigzag line.
The Magnetic Focus Simulator (MFS) is a three-dimensional finite-element method code. It is used to model the magnetic field in the microwave tube and supplies the external magnetic field for the Electron Optics Simulator (EOS) and the Beam Wave Interaction Simulator (BWIS).
A low cost agricultural waste buckwheat hull after extracted natural pigment was used as bisorobent for removal of a cationic dye methylene blue from aqueous solution. The sorbent was characterized by FTIR, scanning electron microscopy (SEM), and potentiometric mass titration. The results showed that buckwheat hull is porous material with functional groups such as hydroxyl and carboxyl, and the pHzcp...
A one dimensional nonlinear time-dependent theory for helix traveling wave tubes in beam-wave interaction is studied. A generalized electromagnetic field is applied to the expression of radio frequency field. The substitution of a spatial average over a wavelength for a time average over a wave period is used in the equation of radio frequency field. The space charge field of electron beam is treated...
This paper presents the application of hierarchical vector finite element method (FEM) with second-order basis for modeling slow-wave structures (SWSs) in microwave tubes, and consequently, a robust, fast and efficient multigrid eigensolver (MGES) is developed to simulate the SWSs.
This paper presents a new framework for the assembly planning of aircraft which integrates assembly sequence planning (ASP) with CAPP on the basis of the standardized mathematical model of polychromatic sets. This paper fulfills three main tasks including the selection of location mode and assembly equipments, assembly sequence planning, and assembly process planning based on a unified model, which...
In this paper, the inverse kinematics and dynamics of the 3-RRRT parallel manipulator with three translational degrees of freedom are investigated. First, the equations of kinematics have been formulated by using close-vector approach. Then, the angular velocities and accelerations of the manipulator are developed. Furthermore, the inverse dynamics for the manipulator is performed by using Lagrange...
This paper presents an amphibious snake-like robot's design. This amphibious snake-like robot, mainly composed by 8 Modular Universal Units, is waterproof and can move smoothly in the water while pressurized with O-rings and other essential accessories. The control equations for each gait are introduced. Due to its special joint design and the feature of being densely covered by vanes, the robot is...
The control of a snake-like robot is a challenging problem because of the complex dynamics. In this paper, we present a novel method, called passive creeping, to control the serpentine locomotion of the snake-like robot. The kernel of this method is composed of the following two concepts: 1) dynamic shift brings the tendency toward the serpentine locomotion; and 2) energy links the environments and...
Through the application of the constraint accession method for configuration design to the new parallel robot manipulator (PRM) of the partly degrees of freedom (DOF), and three new types of 3-DOF PRM are designed in the paper. According to the kinematics theory, the constrains, the degrees of freedom, position and velocity are analyzed. Using space coordinate transformation theory of Jacobian matrix...
A snake-like robot can locomote in various environments; and it can manipulate objects when one end is fixed. A method of dynamic modeling for locomotion-manipulation of the snake-like robot is developed in order to unify the dynamic equations of two states. A virtual structure for orientation and position and the product-of-exponentials formula describe the mechanism and the kinematics of the robot...
In this paper, we propose a new interference alignment (IA) scheme designing jointly the linear transmitter and receiver for the 2 user MIMO X channel system, using minimum total mean square error criterion, subject to each transmitter power constraint. Considering the channel estimation errors, we further propose a robust design for the IA. Iterative method is used to obtain the optimal solutions...
This paper presents an advanced switched model approach for vapor compression cycle (VCC) systems with shut-down and start-up operations. Building upon recent work [2], a full dynamic system model with switched moving-boundary components is presented that is able to accommodate severe transients in heat exchanger dynamics. These new switched heat exchanger models are created with uniform model structures,...
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