An intelligent control method based on artificial neural network for numerical flight simulation of the basic finner projectile with pitching maneuver

In this paper,an intelligent control method applying on numerical virtual flight is proposed.The proposed algorithm is verified and evaluated by combining with the case of the basic finner projectile model and shows a good application prospect.Firstly,a numerical virtual flight simulation model based on overlapping dynamic mesh technology is constructed.In order to verify the accuracy of the dynamic grid technology and the calculation of unsteady flow,a numerical simulation of the basic finner projectile without control is carried out.The simulation results are in good agreement with the experiment data which shows that the algorithm used in this paper can also be used in the design and evaluation of the intelligent controller in the numerical virtual flight simulation.Secondly,combined with the real-time control requirements of aerodynamic,attitude and displacement parameters of the projectile during the flight process,the numerical simulations of the basic finner projectile’s pitch channel are carried out under the traditional PID(Proportional-Integral-Derivative)control strategy and the intelligent PID control strategy respectively.The intelligent PID controller based on BP(Back Propagation)neural network can realize online learning and self-optimization of control parameters according to the acquired real-time flight parameters.Compared with the traditional PID controller,the concerned control variable overshoot,rise time,transition time and steady state error and other performance indicators have been greatly improved,and the higher the learning efficiency or the inertia coefficient,the faster the system,the larger the overshoot,and the smaller the stability error.The intelligent control method applying on numerical virtual flight is capable of solving the complicated unsteady motion and flow with the intelligent PID control strategy and has a strong promotion to engineering application.

Mussel-inspired PTW@PDA composites for developing high-energy gun propellants with reduced erosion and enhanced mechanical strength

The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.

A Post-Quantum Cross-Domain Authentication Scheme Based on Multi-Chain Architecture

Due to the rapid advancements in network technology,blockchain is being employed for distributed data storage.In the Internet of Things(IoT)scenario,different participants manage multiple blockchains located in different trust domains,which has resulted in the extensive development of cross-domain authentication techniques.However,the emergence of many attackers equipped with quantum computers has the potential to launch quantum computing attacks against cross-domain authentication schemes based on traditional cryptography,posing a significant security threat.In response to the aforementioned challenges,our paper demonstrates a post-quantum cross-domain identity authentication scheme to negotiate the session key used in the cross-chain asset exchange process.Firstly,our paper designs the hiding and recovery process of user identity index based on lattice cryptography and introduces the identity-based signature from lattice to construct a post-quantum cross-domain authentication scheme.Secondly,our paper utilizes the hashed time-locked contract to achieves the cross-chain asset exchange of blockchain nodes in different trust domains.Furthermore,the security analysis reduces the security of the identity index and signature to Learning With Errors(LWE)and Short Integer Solution(SIS)assumption,respectively,indicating that our scheme has post-quantum security.Last but not least,through comparison analysis,we display that our scheme is efficient compared with the cross-domain authentication scheme based on traditional cryptography.

Crystallization thermodynamics of 2,4(5)-dinitroimidazole in binary solvents

2,4(5)-Dinitroimidazole(2,4(5)-DNI)is an important organic intermediate,and itself can also be used for energetic material.In this work,the solubility of 2,4(5)-DNI in(methanol+water,acetonitrile+water,acetone+water)binary solvents were measured by using a dynamic test method from 278.15 K to 323.15 K under 101.1 k Pa.The Jouyban–Acree model,van't Hoff–Jouyban–Acree model,Apelblat–Jouyb an–Acree model,Ma model,and Sun model were used to correlate the experimental data.The values of relative average deviation(RAD)and root-mean-square deviation(RMSD)were very small,indicating that the error between the experimental value and the correlated value was very small.The thermodynamic parameters such as dissolution enthalpy,dissolution entropy and Gibbs energy were calculated based on solubility data.High-purity of 2,4(5)-DNI was efficiently obtained by using cooling and dilution crystallization method.

Differential flatness-based distributed control of underactuated robot swarms

This paper proposes a distributed control method based on the differential flatness(DF) property of robot swarms. The swarm DF mapping is established for underactuated differentially flat dynamics, according to the control objective. The DF mapping refers to the fact that the system state and input of each robot can be derived algebraically from the flat outputs of the leaders and the cooperative errors and their finite order derivatives. Based on the proposed swarm DF mapping, a distributed controller is designed. The distributed implementation of swarm DF mapping is achieved through observer design. The effectiveness of the proposed method is validated through a numerical simulation of quadrotor swarm synchronization.

Direct ink writing of 3D-Honeycombed CL-20 structures with low critical size

3D-Honeycombed CL-20 structures with low critical size of detonation have been fabricated successfully for intelligent weapon systems using a micro-flow direct ink writing(DIW) technology.The CL-20-based explosive ink for DIW technology was prepared by a two-component adhesive system with waterborne polyurethane(WPU) and ethyl cellulose(EC).Not only the preparation of the explosive ink but also the principle of DIW process have been investigated systematically.The explosive ink displayed stro ng shea rthinning behavior that permitted layer-by-laye r deposition from a fine nozzle onto a substrate to produce complex shapes.The EC content was varied to alter the pore structure distribution and rheological behavior of ink samples after curing.The deposited explosive composite materials are of a honeycombed structure with high porosity,and the pore size distribution increases with the increase of EC content.No phase change was observed during the preparation process.Both WPU and EC show good compatibility with CL-20 particles.Apparently high activation energy was realized in the CL-20-based composite ink compared with that of the refined CL-20 due to the presence of non-energetic but stable WPU.The detonation performance of the composite materials can be precisely controlled by an adjustment in the content of binders.The 3D honeyco mbed CL-20 structures,which are fabricated by DIW technology,have a very small critical detonation size of less than 69 μm,as demonstrated by wedge shaped charge test.The ink can be used to create 3D structures with complex geometries not possible with traditional manufacturing techniques,which presents a bright future for the development of intelligent weapon systems.

Extended optimal guidance law with impact angle and acceleration constriants

The extended optima straints of miss distance and Schwartz inequality. To reduce guidance law with terminal conmpact angle is derived by the terminal acceleration and eliminate gravity disturbance absolutely, the object function, which designs the weight of control command to be the power function of time-to-go＇s reciprocal, is given. And the gravity is considered when building the state equation. Based on the parsing express of the guidance command change with varying time and adjoint system analysis method, the command characteristics and the non-dimensional miss distance of the guidance law are analyzed, a design principle of guidance order coefficients is discussed. Finally, based on the requirement of engineering, the method to calculate the guidance condition and maximal required acceleration of the guidance law is given. The simulation demonstrates that not only the guidance law can satisfy the terminal position and impact angle constraints, but also the terminal acceleration can be converged toward zero, which will support a good situation for the terminal angle of attacking control.

Time-to-go weighted optimal trajectory shaping guidance law

For maneuvering target, the optimal trajectory shaping guidance law which can simultaneously achieve the designed specifications on miss distance and final impact angle was deduced using optimal control theory based on the time-to-go weighted function. Based on the same cost function, the closed-form solutions of the guidance law were derived when the initial displacement of missile, final impact angle, heading error and target maneuver was introduced into the lag-free guidance system. To validate the closed-form solutions, the simulation of the lag-free system was done and the simulation results exactly matched the closed-form solutions and only when the exponent is greater than zero, the final acceleration approaches to zero.

Primary analysis and screening of microRNAs in gastric cancer side population cells

AIM: To explore the micro RNA(mi RNA) profiles and to determine the key mi RNAs within the side population(SP) cells of the gastric cancer cell line MKN-45. METHODS: We used fluorescence-activated cell sorting and Hoechst 33342 labeling to obtain SP cells from the human gastric carcinoma cell line MKN-45. The mi RNA expression profiles of the SP and major population(MP) cells were examined using a mi RNA gene chip, and key mi RNAs were obtained according to aberrant expression and the mi RNAs' possible targets as predicted by bioinformatics. RESULTS: Using a significance criterion of a 1.5-fold or greater difference in expression level, we observed an increase in the expression of 34 mi RNAs and a decrease in the expression of 34 mi RNAs when comparing SP to MP cells. Using quantitative real-time reverse transcription-polymerase chain reaction to test for differentially expressed mi RNAs combined with bioinformatics results, we found that the downregulated mi RNAs, such as hsa-mi R-3175 and hsa-mi R-203, and the upregulated mi RNAs, including hsa-mi R-130 a, hsa-mi R-324-5p, hsa-mi R-34 a, and hsa-mi R-25-star, may be important in maintaining and regulating the characteristics of SP cells. CONCLUSION: There are key mi RNAs expressed within the SP cells of the gastric cancer cell line MKN-45, andinclude hsa-mi R-3175, hsa-mi R-203, hsa-mi R-130 a, hsami R-324-5p, hsa-mi R-34 a, and hsa-mi R-25-star.

Adaptive weighting impact angle optimal guidance law considering seeker's FOV angle constraints

In this paper, a new adaptive optimal guidance law with impact angle and seeker’s field-of-view(FOV) angle constraints is proposed. To this end, the generalized optimal guidance law is derived first. A changeable impact angle weighting(IAW) coefficient is introduced and used to modify the guidance law to make it adaptive for all guidance constraints. After integrating the closed-form solution of the guidance command with linearized engagement kinematics, the analytic predictive models of impact angle and FOV angle are built, and the available range of IAW corresponding to constraints is certain. Next, a calculation scheme is presented to acquire the real-time value of IAW during the entire guidance process. When applying the proposed guidance law, the IAW will keep small to avoid a trajectory climbing up to limit FOV angle at an initial time but will increase with the closing target to improve impact position and angle accuracy, thereby ensuring that the guidance law can juggle orders of guidance accuracy and constraints control.

3D direct writing and micro detonation of CL-20 based explosive ink containing O/W emulsion binder

The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a novel CL-20 based explosive ink formulation have been developed successfully for MEMS initiation systems via DIW technology.We designed PVA/GAP into an oil-in-water(O/W)emulsion,in the way that the aqueous solution of PVA as water phase,the ethyl acetate solution of GAP as oil phase,the combination of Tween 80 and SDS as emulsifier,BPS as a curing agent of GAP.The ideal formulation with good shear-thinning rheology properties and clear gel point was prepared using only 10 wt%emulsion.The dual-cured network formed during the curing process made the printed sample have good mechanical properties.The printed samples had satisfactory molding effect without cracks or fractures,the crystal form of CL-20 not changed and the thermal stability have improved.Deposition of explosive inks via DIW in micro-scale grooves had excellent detonation performances,which critical detonation size was 1×0.045 mm,detonation velocity was 7129 m/s and when the corner reaching 150°can still detonated stably.This study may open new avenues for developing binder systems in explosive ink formulations.

Research on Maintenance Information Management System for Distributed Manufacture System

An architecture and design of a maintenance information management system for distributed manufacture system is presented in this paper, and its related key technologies are studied and implemented also. A frame of the maintenance information management system oriented human-machine monitoring is designed, and using object-oriented method, a general maintenance information management system based on SQL server engineering database and adopted client/server/database three-layer mode can be established. Then, discussions on control technologies of maintenance information management system and remote distributed diagnostics and maintenance system are emphasized. The system is not only able to identify and diagnose faults of distributed manufacture system quickly, improve system stability, but also has intelligent maintenance functions.

Design and manufacture of a 100 kA coaxial pulsed power cable for plasma generator and PPS in ETC guns

Based on our previous pulsed current and internal overvoltage test data and the experience of common commercial high power cables,a 100 kA coaxial pulsed power cable is designed and manufactured to adapt the coaxial electric energy breech transmission between the plasma generator and the pulsed power supply(PPS) in electrothermal-chemical(ETC) guns.The index parameters are analyzed and determined.Semi-conductor layers and a shield stiffener are introduced to prevent the deformation and burst of the pulsed power cable structurally.The semi-conductor layer can eliminate the air gap and balance the electric field in the cable.The shield stiffener can multiply the mechanical strength to restrain the strong electrodynamic force produced by the core dislocation of the outer conductor.The multi-coupling of electromagnetic field,stress field and thermal field analysis are established to assist in aided design of electrical strength,mechanical strength and temperature rise characteristics.Both a DC voltage withstand test and pulsed discharge tests are introduced to verify and inspect the performance and dynamic response of the pulsed power cable.The 25 kV/5 min DC voltage withstand test result shows that the sample leakage current is nearly 3 μA and no abnormal phenomena of the pulsed power cable sample occurred.The pulsed discharge tests show that the sample can sustain the 100 kA peak current.Furthermore,this 100 kA coaxial pulsed power cable can satisfy the ETC test requirements.

Two types of coaxial self-balancing robots

Two types of coaxial self-balancing robots(CSBR)were proposed,one can be used as a mobile robot platform for parts transporting in unmanned factory or as an inspector in dangerous areas,and the other can be used as a personal transporter ridden in cities.Mechanical designing and control structures as well as control strategies were described and compared in order to get a general way to develop such robots.A state feedback controller and a fuzzy controller were designed for the robot using DC servo motors and the robot using torque motors,respectively.The experiments indicate that the robots can realize various desired operations smoothly and agilely at the velocity of 0.6 m/s with an operator of 65 kg.Furthermore,the robustness of the controllers is revealed since these controllers can stabilize the robot even with unknown external disturbances.

Development of CAD software package of intellectualized casting technology

Based on the numerical simulation of solidification, a computer aid design(CAD) software package of casting technique was developed to design the rising system intelligently. The software can calculate the size and locate the situations of the isolated melts. According to the liquid shrinkage of each isolated melts and the standard parameters of risers in the database, the riser’s situation and the size can be identified intelligently as long as the riser’s shape is selected. 3-D software and simulation analysis of CAST soft/computer aid engineering(CAE) software show that the design of the riser and the running system is feasible.

Test on an Optimized Cylindrical Non-contact Piezoelectric Actuator

An optimization design for the cylindrical non-contact piezoelectric actuator is presented after analyzing the acoustic radiation pressure and acoustic viscous force.By adding the specific microstructure on the rotor to alter the near-field sound effect and maximize the use of high intensity acoustic field induced by the stator to drive the rotor,the rotor speed is increased.The finite element analysis of the acoustic field induced by a variety of rotors with different structures is conducted,A prototype is manufactured,the speed-test system for the actuator is built,and the driving characteristics are measured.The results suggest that the rotation speed of the rotor can reach 4 167r/min,which demonstrates that the driving characteristics of cylindrical non-contact piezoelectric actuator are successfully improved using the optimization method proposed.

Method for high reliability evaluation of explosive initiator based on sensitivity distribution order restricted theory

Based on the hypothesis testing theory and sampling inspection, and utilizing the distribution parameters obtained by order restricted method, the matter of reliability index verification is transformed into testing the scale parameters of distribution. Thus, a lower stimulus level is selected, and small sample size specimens are tested to verify the high reliability at required stimulus level. Analysis for mean square error of verification test stimulus level is taken, and the result demonstrates that it is reasonable to confirm the test scheme using the order restricted estimation. The new method is used for reliability verification of the stab detonator comparing with run-down method. The result shows that it is available for verification of high reliability explosive initiator by small sample size.

Measurement of time-varying electron density of the plasma generated from a small-size cylindrical RDX explosion by Rayleigh microwave scattering

It is challenging to measure the electron density of the unsteady plasma formed by charged particles generated from explosions in the air,because it is transient and on a microsecond time scale.In this study,the time-varying electron density of the plasma generated from a small cylindrical cyclotrimethylenetrinitramine(RDX)explosion in air was measured,based on the principle of microwave Rayleigh scattering.It was found that the evolution of the electron density is related to the diffusion of the detonation products.The application of the Rayleigh microwave scattering principle is an attempt to estimate the electron density in explosively generated plasma.Using the equivalent radius and length of the detonation products in the bright areas of images taken by a high-speed framing camera,the electron density was determined to be of the order of 10^(20)m^(−3).The delay time between the initiation time and the start of variation in the electron-density curve was 2.77–6.93μs.In the time-varying Rayleigh microwave scattering signal curve of the explosively generated plasma,the electron density had two fluctuation processes.The durations of the first stage and the second stage were 11.32μs and 19.20μs,respectively.Both fluctuation processes increased rapidly to a peak value and then rapidly attenuated with time.This revealed the movement characteristics of the charged particles during the explosion.

Design and application of wireless signal strength measurement system on the near-ground

The wireless communication system's performance is greatly constrained by the wireless channel characteristics,especially in some specific environment.Therefore,signal transmission will be greatly impacted even if not in a complicated topography.Testing results show that it is hardly to characterize the radio propagation properties for the antenna installed on the ground.In order to ensure a successful communication,the radio frequency(RF)wireless signal intensity monitor system was designed.We can get the wireless link transmission loss through measuring signal strength from received node.The test shows that the near-ground wireless signal propagation characteristics still can be characterized by the log distance propagation loss model.These results will conduce to studying the transmission characteristic of Near-Earth wireless signals and will predict the coverage of the earth's surface wireless sensor network.

Extended trajectory shaping guidance law considering a first-order autopilot lag

To satisfy the terminal position and impact angel constraints,an optimal guidance problem was discussed for homing missiles. For a stationary or a slowly moving target on the ground,an extended trajectory shaping guidance lawconsidering a first-order autopilot lag（ ETSG L-C FAL） was proposed. To derive the ETSG L-C FAL,a time-to-go- nth power weighted objection function was adopted and three different derivation methods were demonstrated while the Schwartz inequality method was mainly demonstrated.The performance of the ETSG L-C FAL and the ETSG L guidance laws was compared through simulation.Simulation results showthat although a first-order autopilot is introduced into the ETSG L-C FAL guidance system,the position miss distance and terminal impact angle error induced by the impact angle is zero for different guidance time.