As a kind of flexible aircraft, the aerodynamic configuration of airship is maintained by superpressure of internal gas completely. And the pressure difference must be controlled in a safe range. Aiming at these issue...
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ISBN:
(纸本)9781479947249
As a kind of flexible aircraft, the aerodynamic configuration of airship is maintained by superpressure of internal gas completely. And the pressure difference must be controlled in a safe range. Aiming at these issues, the models of pressure difference and solar radiation are built. Combining with the airship thermodynamic model, pressure control is achieved. A method of direct control is presented. According to the pressure value of atmosphere and the desired pressure difference, the internal pressure of airship that needs to be maintained can be figured out. And the change of internal gas can be obtained accordingly. Aiming at the hovering phase, the models and the control method are simulated. The control results of pressure difference and the thermodynamic properties are obtained, which illustrate the effectiveness of control method.
Tea,a globally cultivated crop renowned for its uniqueflavor profile and health-promoting properties,ranks among the most favored functional beverages ***,diseases severely jeopardize the production and quality of tea l...
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Tea,a globally cultivated crop renowned for its uniqueflavor profile and health-promoting properties,ranks among the most favored functional beverages ***,diseases severely jeopardize the production and quality of tea leaves,leading to significant economic *** early and accurate identification coupled with the removal of infected leaves can mitigate widespread infection,manual leaves removal remains time-con-suming and *** robots for pruning can significantly enhance efficiency and reduce ***-ever,the accuracy of object detection directly impacts the overall efficiency of pruning *** complex tea plantation environments,complex image backgrounds,the overlapping and occlusion of leaves,as well as small and densely harmful leaves can all introduce interference *** algorithms perform poorly in detecting small and densely packed *** address these challenges,this paper collected a dataset of 1108 images of harmful tea leaves and proposed the YOLO-DBD *** model excels in efficiently identifying harmful tea leaves with various poses in complex backgrounds,providing crucial guidance for the posture and obstacle avoidance of a robotic arm during the pruning *** improvements proposed in this study encompass the Cross Stage Partial with Deformable Convolutional Networks v2(C2f-DCN)module,Bi-Level Routing Atten-tion(BRA),Dynamic Head(DyHead),and Focal Complete Intersection over Union(Focal-CIoU)Loss function,enhancing the model’s feature extraction,computation allocation,and perception *** to the baseline model YOLOv8s,mean Average Precision at IoU 0.5(mAP0.5)increased by 6%,and Floating Point Operations Per second(FLOPs)decreased by 3.3 G.
A high precision and novel modeling method, to identify the aerodynamic parameters of the parafoil based on CFD(Computational Fluid Dynamics) is proposed. By solving the governing equations and the k-ε equations, the...
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ISBN:
(纸本)9781538629185
A high precision and novel modeling method, to identify the aerodynamic parameters of the parafoil based on CFD(Computational Fluid Dynamics) is proposed. By solving the governing equations and the k-ε equations, the effects of leading edge incision of the parafoil on aerodynamic performance and stability are investigated. It is concluded that increasing the length and slope of the leading edge incision can decrease the lift coefficient and increase the drag coefficient, the stall angle of attack and lift to drag ratio are also decreased. The slope angle and the length have different effects on aerodynamic performance of the parafoil. Increasing the length affects the pressure distribution of the upper and lower wing surface. Increasing the slope leads to airflow separation at the trailing edge of the parafoil. Then, the variation of lift coefficients with time is obtained by adding different types of wind into the flow field on the basis of field velocity approach. By comparing the flow field of different models, it can be found that reducing the incision length and the slope are beneficial to enhance the stability of the parafoil.
Near space aircraft enters a glide phase after the boost phase.A low glide altitude can reduce the hostile warning time to enhance penetration *** a lower boost phase altitude is *** trajectory optimization of the boo...
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ISBN:
(纸本)9781538629185
Near space aircraft enters a glide phase after the boost phase.A low glide altitude can reduce the hostile warning time to enhance penetration *** a lower boost phase altitude is *** trajectory optimization of the boost phase for a three-stage solid rocket is an optimal control problem subject to various *** problem is reformulated as a nonlinear programming by using Gauss pseudospectral method（GPM）.The angle of attack sequence satisfying the constraint conditions can be obtained by using sequential quadratic programming（SQP）.Finally,simulation results verify the effectiveness of the algorithm.
Social media is profoundly changing our society with its unprecedented spreading power. Due to the complexity of human behaviors and the diversity of massive messages, the information spreading dynamics are complicate...
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This paper proposes a procedure for using an EGARCH-M model in conjunction with Elman neural network when estimating the return series of USD/CNY exchange *** analysis shows that the returns of USD/CNY exchange rate a...
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ISBN:
(纸本)9781509009107
This paper proposes a procedure for using an EGARCH-M model in conjunction with Elman neural network when estimating the return series of USD/CNY exchange *** analysis shows that the returns of USD/CNY exchange rate are fat-tails and have volatility *** EGARCH-M model captures the asymmetry in volatility and the correlation between the return and its past volatility,and the Elman neural network is applied to fit the nonlinear characteristic of the return *** comparing the evaluation index of different models,it proves that the approach of Elman neural network with volatility updating derives a satisfactory empirical *** the forecast of the return series illustrates the excellent performance of the model in the end.
In order to realize safe and accurate homing of powered parafoils with insufficient altitude,a multiphase homing trajectory planning scheme is proposed making use of basic flight characteristics of powered *** the bas...
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ISBN:
(纸本)9781509009107
In order to realize safe and accurate homing of powered parafoils with insufficient altitude,a multiphase homing trajectory planning scheme is proposed making use of basic flight characteristics of powered *** the basis of geometric relationships of each phase trajectory,the problem of trajectory planning is transformed to a parameters optimizing ***,a new particle swarm optimization（PSO） algorithm based on chaos searching（CPSO） is proposed,of which global searching ability and the speed of convergence is significantly ***,CPSO is applied as a tool to optimize the established objective function,and the designed parameters of the multiphase homing trajectory are *** simulation results show that the multiphase homing trajectory of powered parafoils can fulfill the requirements of fixed-point homing and upwind landing under the condition of insufficient initial altitude,which is simple in control and facile in practice as well.
Cooperative targets assignment of multiple Unmanned Combat Aerial Vehicles(UCAVs) is the basis and key issue of multi-UCAVs cooperative combat. The kill probability is taken into consideration in cooperative targets a...
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ISBN:
(纸本)9781479947249
Cooperative targets assignment of multiple Unmanned Combat Aerial Vehicles(UCAVs) is the basis and key issue of multi-UCAVs cooperative combat. The kill probability is taken into consideration in cooperative targets assignment problem, for which a multi-objective MIP model is proposed. The objectives include minimizing the number of launch points taking part in a mission and minimizing the launch time range. An improved efficacy coefficient method is developed to transform the problem to a single-objective MILP model. Numerical experiments show the effectiveness of the proposed approach.
Current trends in software system, such as cloud and big data platform, are leading to rapid and continuing changes. At the same time, these systems will have to react to these changes at runtime to satisfy the potent...
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This paper focus on the simulation experiments of controlling a car by EEG based on imaginary *** collected fourteen channels of brain electroencephalogram（EEG） signals transmitted by Emotiv Epoc+ Neuro *** of emoti...
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ISBN:
(纸本)9781509009107
This paper focus on the simulation experiments of controlling a car by EEG based on imaginary *** collected fourteen channels of brain electroencephalogram（EEG） signals transmitted by Emotiv Epoc+ Neuro *** of emotiv’s own processing and analysis methods,in our program,we wrote wCCA algorithm to preprocess EEG signals,and used Common Spatial Pattern（CSP） to extract the feature of ***,by KNN algorithm we classified the extracted features as imagining feet ＆ righthand movement and neutral state,which correspond to the three control commands（turn forward,turn right,stop） respectively,so that it can control the motions of the simulated car constructed in *** addition,we applied the method of online-learning to greatly improving the classification accuracy,which avoid the time-consuming and laborious off-line training and is closer to real-time status of *** simulation experiments results show that the methods of processing and classification in EEG have better feasibility and *** establishes a basis of practical application for EEG-controlled automobile.
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