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Considering the strong nonlinearity of Unmanned Aerial Vehicles (UAVs) resulting from high Angle of Attack (AoA) and fast maneuvering, we present a multi-model predictive control strategy for UAV maneuvering, which has a small amount of online calculation. Firstly, we divide the maneuver envelope of UAV into several sub-regions on the basis of the gap metric theory. A novel algorithm is then developed to determine the ploytopic model for each sub-region. According to this, a Robust Model Predictive Control based on the Idea of Comprehensive optimization (ICE-RMPC) is proposed. The control law is designed offline and optimized online to reduce the computational expense. Then, the ICE-RMPC method is applied to design the controllers of sub-regions. In addition, to guarantee the stability of whole closed-loop system, a multi-model switching control strategy based on guardian maps is put forward. Finally, the tracking performance of proposed control strategy is demonstrated by an illustrative example.

The hypersonic vehicle has problems with multiple systems coupling and multivariate design. Hence, it is difficult to determine the surrogate model structure of the hypersonic vehicle under larger samples. To solve this problem, this paper proposes a surrogate model structure optimization method based on the idea of PIO algorithm. The method can independently search for a polynomial surrogate model structure that satisfies the accuracy and prediction performance requirements. Through comparative analysis, utilizing this method outperforms Davidson’s genetic programming algorithm. Furthermore, it was applied to the global aerodynamic data fitting and control design of a hypersonic vehicle, and the simulation results reveal that the error of the prediction data obtained by this method was less than 5%, which has a good fitting effect and can meet the engineering application requirements.

An integrated approach that considers the performance limitations of tracking control systems for air-breathing hypersonic vehicles is proposed. First, a set of ascent trajectories is obtained as candidates for tracking control through a trajectory design method that considers the available acceleration. Second, the basic theory of performance limitations, which is adopted to calculate the limits on control performance through the trajectory, is integrated. The open-loop dynamics of air-breathing hypersonic vehicles is responsible for these limits on the control system. Comprehensive specifications on stability, tracking accuracy, and robustness are derived, and the flight envelope with constraints and control specifications is identified. Simulation results suggest that trajectory design should consider restrictions on control performance to obtain reliable solutions. Keywords: Bandwidth constraints, Hypersonic vehicles, Performance limitations, Robust performance, Trajectory tracking control

Aiming to the complex operation condition and strong coupling dynamic characteristics of hypersonic vehicles, this paper develops a parametric model which is suitable to the control integrated design. First, the necessities and research status of the control integrated design of hypersonic vehicles are discussed. Then, the typical hypersonic waverider shape is geometrically parametrized using the quadratic curve and class/shape function methods. After that, the forces and moments of the hypersonic vehicle are estimated based on the surface element method in combination with the engineering estimation formulas, and the nonlinear dynamic parametrization model is built. Furthermore, the analytical expressions of forces and moments are obtained by means of the sensitive analysis strategies as a result that the complicated nonlinear dynamics model is changed to the iterative design model. Finally, an illustrative example is provided to verify the feasibility of this proposed method, and the according results show that the developed parametrization model enables to meet the requirements of the control integrated design.

The emphasis of this paper lies in the development of an efficient approach to reproduce the behaviors of the scramjet-powered hypersonic system with high fidelity. The modeling of the dual-mode scramjet powered hypersonic vehicle dynamics with shock interaction, Ram-to-Scram transition, and finite rate chemistry reaction is firstly introduced. The structure of surrogate model is identified with the implement of iterative fractional factorial design (IFFD). In order to declare the reliability of the surrogate models, ν-gap metric is applied to distinguish the difference among these surrogate models in terms of closed-loop performance. The results show that the influence of Mach number on the aerodynamics should not be overlooked, and the effect of propulsion system to the aerodynamic pitch moment is dramatic. Further, the partial Kriging model appears to have the closest plants throughout the flight envelope compared with the full Kriging model and polynomials model. Nevertheless, considering the briefness of analytical expression, the polynomials model may be an alternative approach for design-oriented modeling.

This paper has researched the influence on body shape design of hypersonic vehicle on flight performance and control stability. Control-oriented parametric model is established, and some important geometric parameters of the parametric model are put into the expression of aerodynamic coefficient to measure the degree of influence on performance. The results show that the length of the elevator influences the control effect and the upper angle of forebody effects on the balanced force and moment significantly. Consequently, the geometric parameters are easily determined in model design and the number of iterations between body system and control design is reduced.

This paper studies the conditions of the successful takeoff and climbing of the aerospace vehicle. By analyzing the longitudinal kinematics model and dynamic model of the vehicle, the take-off constraints determined by integrating with the lift-drag ratio, thrust-to-weight ratio, flight speed and take-off weight. Moreover, the algebraic form of the maximum take-off weight is also derived to ensure that the aircraft can successfully take off under a fixed configuration. Finally, the simulation results verify the effectiveness of the proposed methods.

In order to optimize the structure of anvils, finite element method is used to simulate two kinds of structures, one of which has a support ring but the other one does not. According to the simulated results, it is found that the maximum value of pressure appears at the center of culet when the bevelled angle is about 20°. Comparing the results of these two kinds of structures, we find that the efficiency of pressure transformation for the structure without support ring is larger than that for the structure with support ring. Considering the effect of von Mises stress, two kinds of tungsten carbide opposite anvils have been manufactured with bevelled angle of 10°. The experimental results for these two anvils are in good agreement with the simulation.

With the developing of voltage source converter based multi-terminal dc transmission (VSC-MTDC) technology, DC grid of meshed topology is the trend of VSC-MTDC; moreover, it will be widely used for large scale renewable energy integration. For DC grid of meshed topology, the control aspect is of great importance, while the randomness and volatility of renewable energy will affect the stability of DC grid. The control stability of the VSC-MTDC, especially the control of DC voltage, will face new challenges. This paper focus on the developing trend of VSC-MTDC, the control requirements of DC grid of meshed topology and the effects of large scale renewable energy to the VSC-MTDC are analysed. And mainstream coordinating control strategies under the new situation are compared through the way of theoretical analysis. Simulations based on PSCAD/EMTDC are carried out in a five-terminal meshed VSC-MTDC system with an isolated wind farm, a passive network and three ac synchronized power grids, proving the accuracy of theoretical analysis. Then control characteristics and applicability of the coordinating control strategies for meshed VSC-MTDC with large scale renewable energy integration are concluded.

The equivalent sample theory and its application in analysis of networked control system (NCS) are presented. After analyzing NCS's scheduling in master-slave mode, the characteristics of time delay and sample are summarized. Looking on master station visiting the slave station as a special sample process, the theory of equivalent sample is presented. And based on it, the stability of a kind of NCS is analyzed. The criterion to determine the upper bound of transmission delay is introduced, which guarantees the stability. Finally, an example with simulation shows the availability and usability of this analysis method.

In the light of the broad range of hypersonic flight conditions, a design method of switching control based on guardian maps is proposed to guarantee the global stability within the flight envelope. First, a linear parameter varying (LPV) model of a hypersonic vehicle is established over a range of hypersonic flight conditions. The parameters of controller are determined by pole placement technology with the target pole locations at the boundaries of the parameters variation range. Second, a new range of flight conditions that ensures system stability with current controller is analyzed based on guardian maps. The execution of the iterative process is used to determinate the set of controller parameters overall the flight envelope with initial target pole locations. By switching controller parameters the closed-loop performance is guaranteed over the entire flight envelope. The simulation shows that the proposed design method has the ability to ensure the global stability over the flight envelope, and achieving good tracking performance.

The Flush Airdata Sensing (FADS) system and its pressure model are presented briefly. The improved algorithm for calculating the impact pressure, static pressure and modifying coefficient are studied. First, the non-linear equations are simplified using Moore-Penrose inverse. Then the impact pressure and static pressure are computed with the improved iteration and BP neural network. Both the two improved algorithms meet the requirements of the flush airdata sensing system on precision, reliability and speed. BP neural network has great advantages on real-time requirements, for it needs only 5% time to reach the required precision comparing to the original algorithm.

Cancer stem cells (CSCs) are proposed to be responsible for high recurrence rate in cervical carcinoma. Reagents that can suppress the proliferation and differentiation of CSCs would provide new opportunities to fight against tumor recurrence. Doxycycline has been reported as a potential anti-cancer compound. However, few studies investigated its inhibitory effect against cervical cancer stem cells.HeLa cells were cultured in cancer stem cell conditional media in a poly-hema-treated dish. In this non-adhesive culture system, HeLa cells were treated with cisplatin until some cells survived and formed spheroids, which were then collected and injected into the immunodeficient mice. Cisplatin was administered every three days for five times. The tumor xenografts with CSC enrichment were cultured in cancer stem cell specific medium again to form tumorsphere, which we called HeLa-CSCs. Expression of cancer stem cell markers in HeLa-CSCs was measured by flow cytometry and qPCR. HeLa-CSCs were then treated with doxycycline. Proliferation and differentiation rates were determined by the size of spheres formed in vitro and tumor formed in vivo.We developed a new strategy to selectively enrich CSCs from human cervical carcinoma cell line HeLa, and these HeLa-CSCs are CD133+/CD49f+ cell populations with significantly enhanced expression of stem cell markers. When these HeLa-CSCs were treated with doxycycline, the colony formation, proliferation, migration and invasion, and differentiation were all suppressed. Meanwhile, stem cell markers SOX-2, OCT-4, NANOG, NOTCH and BMI-1 decreased in doxycycline treated cells, so as the surface markers CD133 and CD49f. Furthermore, proliferation markers Ki67 and PCNA were also decreased by doxycycline treatment in the in vivo xenograft mouse model.Cancer stem cells are enriched from sphere-forming and chemoresistant HeLa-derived tumor xenografts in immunodeficient mice. Doxycycline inhibits proliferation, invasion, and differentiation, and also induces apoptosis of these HeLa-CSCs in vitro and in vivo.

In thc coursc of TF/TA 2 (Terrain Following/ Terrain Avoidance/ Threat Avoidance), it is necessary to do flight mission planning by which to obtain the optimal flight route based on the information of terrain feature. culture and threats in the mission area. so as to increase the aircraft's survivability in the flight mission. This paper uses Genetic Algorithm to optimize the flight route. The description of the cost function in the low altitude flight and penetration is discussed. The special structures of the chromosomes and genes in the algorithm arc designed. Furthermore, simulations in different types of flight areas are presented. Their results show that this method is better than Dynamic Programming and thc gradient method.

I am an unmarried young woman. Recently I have been troubled by my love problem. It is like this: A year ago I began falling in love with a young man. He is a member of the Communist Party and is very serious and responsible in his studies and work; last year he was voted a progressive worker in the factory. In the past six months we have come to a definite understanding, and we get along very well. But because his father's income is not good, and his mother does not have a job, and his brothers and sisters are too young, his family is not financially secure. My close girlfriends at the factory try very hard to advise me [against him]: "When you select a mate, the economic factors are most important. With your qualifications you can be much more selective." Some even say: "In selecting a [boy] friend, you have to be more practical. You have to find someone with a better financial condition. This one of yours has "baggage" in the older generation and "burden" in the younger generation. How can you live com...