Complex products with high turnover and short shelf life are characterized by a higher order frequency. Traditional value chain design is mostly based on the time series of order data of complex products and the impact of sales volume on sales cycle, while ignoring the detail information contained in the order frequency, which is difficult to accurately capture the rapidly changing supply and demand relationship between multi-agents. In order to solve this problem, a collaborative design method of complex product lifecycle value chain fusing multi-agent demand frequency characteristics was proposed. Firstly, the frequency sequence extraction method of gated convolution was used to identify the multi-agent requirement; Secondly, the Transformer time series prediction model based on frequency segmentation was integrated into the order frequency information, and the lifecycle value chain was built according to the improved time series frequency multi-head self-attention (seq-fre multi-head attention) structure. The time series and frequency characteristics of different segments corresponded to different attention heads to realize the fusion of multi-stage time series and frequency features; Finally, the new value chain collaborative design method was applied to the multi-agent demand prediction problem of a complex product, and experimental verification was carried out. The result showed that the proposed value chain collaborative design method fusing demand frequency features has high prediction accuracy and good application prospects.

Aiming at the problem that some electromechanical products fail to comprehensively consider the requirements of customer and environment in the conceptual design stage, which affects the detailed design of products, a method for generating green conceptual design scheme of electromechanical products based on the function?structure?requirements of customer and environment (FSRce) model is proposed. Firstly, the nodes in the existing product design tree were extended and associated by selecting appropriate functions and structures from the case library; at the same time, the importance of customer and environment requirements of the product was obtained by means of data mining, expert scoring and other methods to construct the conceptual design space of product based on the FSRce model. Then, the weighted interval roughness method was used to analyze the importance of customer and environment requirements to obtain the relative importance of requirements, and then the fuzzy quality function deployment (FQFD) was used to transform the relative importance of requirements into the engineering characteristic weights of the product. Finally, the matter-element theory was used to construct the matter-element domain of product and the matter-element set of each structure based on engineering characteristics and the satisfaction scores of each structure were obtained by combining the weights of engineering characteristics, and the optimized product conceptual design scheme that met the requirements of customer and environment was selected by comparing the satisfaction. Taking a small industrial blower as an example, the conceptual design scheme was optimized based on the above method. Compared with the original scheme, the optimized blower reduced the energy consumption by 15.38%, reduced the carbon emission by 15.32%, and improved the satisfaction by 44.66%, which verified the feasibility and effectiveness of the proposed method. The proposed method provides a new way to generate the conceptual design scheme of electromechanical products, which can better assist designers to realize the green design of electromechanical products.

In order to improve the folding rate and support performance of deployable mechanisms, a scissor deployable mechanism with variable Poisson motion characteristics is proposed and its kinematics analysis is conducted. Firstly, a thick panel support unit with single-closed-loop was proposed and applied to sandwich structures. Through analyzing the influence of different shape sandwich layers on the support stiffness of sandwich structure by using ANSYS Workbench software, it was found that the sandwich structure with thick plate support unit had better support effect and smaller mass, and the positive and negative Poisson' ratio could be switched by changing the structural design parameters. Secondly, according to the definition of Poisson' ratio, a regular n-sided scissor deployable mechanism with variable Poisson motion characteristics was designed. Based on the screw theory, the screw constraint topology graph of the closed-loop deployable mechanism was drawn to analyze its degree of freedom as 1. The deployable mechanism was divided into three modules, and the principle and process of modular longitudinal expansion were described. Finally, the kinematics model of the m-layer regular n-sided scissor deployable mechanism was established and the prototype of the regular quadrilateral scissor deployable support structure was set up to further verify the variable Poisson motion characteristics of the mechanism, which could provide a theoretical basis for the follw-up research.

The production process of high-performance hydraulic cylinders is flexible and has a long processing cycle. Its production belongs to a typical non-standard, single piece, small batch discrete manufacturing model, which is difficult to optimize and control in design and production. A high-performance intelligent design and manufacturing platform for hydraulic cylinders was designed to address the issues of low software integration and high coupling when using digital design and process control software for hydraulic cylinder production enterprises. Through reconfigurable middleware technology, the platform integrated software interfaces such as AutoCAD and SolidWorks. While integrating neural network algorithms and multi-objective optimization techniques, digital design and production control modules such as graph library, working hour prediction, and flexible process planning were constructed. The digital design and manufacturing platform can achieve full lifecycle control of the design and manufacturing process, providing strong support for manufacturing enterprises to achieve digital transformation.

An intelligent recognition approach was proposed, which was based on information fusion and a multi-granularity cascaded forest model (IFMCFM) to tackle the challenge of low reliability in excavator working stage identification methods. Information fusion technology was utilized to merge the category probability vector of the excavator working stage with high-importance features, thereby forming new identification features. The novel features were subsequently fed into the cascaded forest model, which was trained using different proportions of the training set. Subsequent analysis was carried out on the identification results. The identification outcomes of IFMCFM were compared with those of other models, including DAGSVM (directed acyclic graph support vector machine), PCA-SVM (support vector machine based on principal component analysis), LIBSVM (library for support vector machines), and LSTM (long short-term memory). The research findings revealed that the recognition accuracy, recall, and F₁ (harmonic average of accuracy and recall) index of IFMCFM were 95.00%, 95.17%, and 95.02% respectively, indicating good recognition performance when the training set ratio was 80%. In comparison to the other identification models, the highest accuracy and reliability were exhibited by IFMCFM. IFMCFM can effectively identify the operation stage of excavators and has high application value.

Aiming at the problem that the first order reliability analysis method commonly used in engineering has insufficient accuracy in solving the reliability of limit state function with high nonlinearity, a structural reliability analysis method based on parabolic approximation is proposed on the basis of second order reliability analysis method. Firstly, the first order reliability analysis method was used to iteratively solve the most probable point in standard normal space. Then, the vector composed of the most probable point and the coordinate origin was taken as the new coordinate axis, and the approximate parabola was constructed based on the curvature of the most probable point in each direction of the limit state function to improve the approximate accuracy of the boundary region. Finally, the approximate parabola on the new axis was integrated according to the standard normal distribution probability density to solve the structural reliability probability. The first order reliability method, the second order reliability method and the reliability analysis method based on the second order parabola approximation were compared by four examples to verify the feasibility of the proposed method. The results showed that when facing the reliability problems with high nonlinearity, the accuracy of the first order reliability method was low and the second order reliability method might make solving errors in special cases, while the parabolic approximate integral method could effectively improve the accuracy of structural reliability analysis and ensure the stability of the solution. The research results can provide reference for reliability analysis of complex structures.

Hierarchical Bayes or E-Bayes is frequently used to estimate the failure probability when building a zero-failure reliability estimation model utilizing the concept of a distribution curve. The overall accuracy of reliability point estimation is not high bacause of the limited estimation ability. A new double-modified hierarchical Bayes method was proposed for the Weibull distribution data to improve the failure probability estimation and accomplish reliability point estimation. On the basis of hierarchical Bayes, the failure probability estimation error was reduced by correcting the upper and lower limits of the failure probability. Combining weighted least squares method and Weibull distribution reliability function determined parameter estimates and reliability curves, thereby obtaining reliability point estimates. Using Monte-Carlo simulation test, the new method could control the relative error of parameter estimation below 10%, and the obtained reliability was closer to the true value. Through the example analysis, the reliability obtained by the new method was closer to the engineering reality when the hyperparameterctook different values. The applicability analysis of the new method showed that the shape parameter \beta was the key factor affecting the estimation accuracy. The new method had obvious advantages and good robustness when \beta >\mathrm{2.2}. The results of the study can provide a reference for the reliability assessment of other life distribution with zero-failure data.

The impact load is an important factor in the structural design of aerospace equipment. The design of thin-walled structures with high load-bearing capacity and good energy-absorbing characteristics is a research focus. Based on Voronoi algorithm, the pseudo-random arrangement of structure similar to honeycomb hexagon was developed by combining the structural characteristics of bone and honeycomb. According to the arrangement of loose inside and tight outside of the bone, a new type of impact resistant structure was constructed by partition design.The impact resistance simulation of bio-inspired thin-walled structure and uniform honeycomb structure of laser selective melted titanium alloy and laser selective sintered carbon fiber/PEEK (polyether ether ketone) composites was conducted to compare the energy-absorbing characteristics of the two kinds of structure. The simulation results showed that the maximum energy-absorption of the bio-inspired thin-walled structure of laser selective melting titanium alloy and laser selective sintered carbon fiber/PEEK composites was increased by 17.7% and 27.7% respectively, compared with the uniform honeycomb structure under axial impact, and the maximum energy-absorption was increased by 422.6% and 99.2% respectively under lateral impact.The bio-inspired thin-walled structure designed has important application prospects in aerospace field.

In order to reduce the risk of the integrated leakage rate measurement test of reactor containment and make the leakage rate test results more conservative and reliable, an optimization method for the integrated leakage rate measurement stage duration of containment for China's nuclear power plants is proposed based on the air stability criteria, function curvature criteria and data distribution criteria. Combined with the adjustment method for the containment integrated leakage rate measurement stage duration of the French Power Group, the determination requirements for the end of integrated leakage rate measurement test for containment were clarified, and an optimization method was proposed to add the criteria for determining the stability of air inside the containment and the termination of integrated leakage rate measurement. Taking 20 groups of containment pressure test samples as examples, the integrated leakage rate measurement stage duration for containment was calculated. The results showed that 17 groups of samples met the optimization conditions, of which 15 groups of samples were able to meet the integrated leakage rate measurement termination criteria within 16 h, and 2 groups of samples met all acceptance criteria within 19.25 h and 18.25 h, respectively. The proposed optimization method can shorten the duration of the integrated leakage rate measurement stage for reactor containment, which is more conservative and reliable than the French method.

The container reach stacker (hereinafter referred to as reach stacker) plays a crucial role in practical port operations. With the increasing attention of society to energy and environmental issues, the electrification trend of reach stackers is becoming more and more significant, and the number of electric reach stackers on the market has been steadily rising year by year. The electric energy consumption performance directly affects endurance capacity, working efficiency and working cost of electric reach stackers, which is one of the important performance of electric reach stackers. Various factors such as driving behavior, operation conditions and equipment malfunctions will have diverse effects on the energy consumption of electric reach stackers. Therefor, by collecting the actual operating data of the customer side of electric reach stackers and based on the LightGBM (light gradient boosting machine) model, the energy consumption modeling for the driving and operational processes of electric reach stackers was conducted at the micro and macro levels, respectively. The SHAP (Shapley additive explanations) theory was used to quantitatively analyze the impact of different operation conditions and behaviors on the energy consumption of reach stackers, while simultaneously identifying energy consumption anomalies caused by equipment malfunctions. The results show that the energy consumption model based on SHAP-LightGBM can accurately predict and analyze the driving and operational energy consumption of reach stackers, which provides valuable input for the design and optimization of energy consumption strategy for electric reach stackers. Additionally, the energy consumption model establishes a theoretical energy consumption benchmark for the actual operational processes of electric reach stackers, effectively guiding driving behavior and identifying energy consumption anomalies caused by malfunctions.

Under the action of elasticity and errors, the efficient and precise modeling of gear contact is a crucial foundation for studying the transmission accuracy of gears. In order to accurately analyze the influence of elasticity and errors on the transmission accuracy of involute cylindrical gears, a semi-analytical contact model for gears considering elastic error is proposed. Taking the involute helical cylindrical gear as an example, firstly, the error tooth surface model of gear was established by combining the tooth surface equation and the tooth profile error, and the error tooth surface equation was obtained. Then, the semi-analytical contact model of gear under the action of elastic error was established by combining analytical method and finite element method, and the deformation coordination equation and force balance equation were derived. Finally, the complete and local finite element model of the gear was conducted, and the transmission error of the gear was calculated by extracting the compliance matrix of the contact tooth surface. The influence of the tooth profile error and elastic deformation on the transmission accuracy of gear was analyzed by using the semi-analytical model, and compared with the finite element simulation results, which verified the efficiency and accuracy of the semi-analytical model. The research results can provide theoretical guidance for the application of involute cylindrical gears in engineering.

Large aperture reflector antenna is the key equipment for deep space exploration and satellite communication. In order to continuously improve the observation performance, the antenna aperture is increasing, and the antenna pointing accuracy requirements are higher and higher. With the increase of antenna aperture, the stiffness of antenna decreases while the windward area increases, which leads to serious flexible deformation of antenna and difficult to guarantee its performance. In order to investigate the influence of flexible deformation of large aperture reflector antenna on electrical performance under ambient wind load, a beam pointing analysis model for antenna is proposed. Firstly, the computational fluid dynamics method was used to numerically simulate the wind pressure distribution on the antenna surface, and the wind pressure coefficient of the antenna surface was obtained. Then, the deformation law of the antenna structure under different wind speed conditions was analyzed by using the independent characteristic of wind pressure coefficient and wind speed. Finally, according to the deformation characteristics of the antenna structure, the variation patterns of gain loss and pointing deviation of the antenna under different working states were analyzed. The results show that the proposed model can quickly evaluate the deformation and beam pointing characteristics of large aperture antennas under wind load, which provides theoretical guidance for the subsequent wind-resistant structure design and system control study of antennas.

In the current civil aircraft cabin door operation panel design, there is a lack of unified standards and specifications for human-machine efficacy and interface design, and the design process overly relies on personal experience and personal preferences, resulting in poor human-machine efficacy of the designed operation panel during use. For this purpose, the design principles for the display and operation of the civil aircraft cabin door operation panel were discussed based on the ergonomics principle, and a design scheme of centralized cabin door operation panel and regional control panel was proposed. Firstly, the information organization, coding, display elements and display forms of the cabin door operation panel were determined through questionnaire survey. Then, the three-dimensional models of the cabin door operation panel, the regional control panel and the aircraft were conducted. Finally, the ergonomics simulation software DELMIA was used to conduct dynamic operation simulation on the layout, key size and touch area of the operation panel. The simulation results showed that the designed cabin door operation panel could enhance the human-machine efficacy, improve the safety and efficiency of the operation, and reduce the misoperation and workload of flight attendants. The designed operation panel and regional control panel not only realize centralized monitoring and management and regional actuation control for the entire cabin door, but also can be used as a human-machine interaction device, which is suitable for the cabin and cargo hold of large-sized wide-body aircraft in the future, and has a very broad application prospect.

Power battery is the core component of new energy vehicle, and its electrochemical and thermal performances are the key to the large-scale promotion and application of new energy vehicle. However, the electrochemical and thermal performances at the macro scale are affected not only by the electrode material characteristics at the micro scale, but also by the battery structural parameters at the mesoscale. In order to reveal the influence mechanism of battery material parameters, electrode structure parameters and battery working parameters on the performance of power battery, taking 18650 nickel-cobalt-manganese ternary power battery lithium as the research object, the influence law of the above parameters on the electrochemical and thermal performances of power battery was explored by constructing the battery electrochemical-thermal coupling model. The material-structure-performance cross-scale correlation effect of power battery was analyzed comprehensively. The results showedt hat the effects of battery material parameters, electrode structural parameters and battery working parameters on the performances of power battery had the characteristic of strong cross-scale correlation.The design and performance optimization of power battery at a single scale can not achieve optimal results, and the material-structure-performance cross-scale design and optimization is the fundamental way to improve the safety and dynamic performances of power battery.

In order to further improve the response speed and lightweight extent of piezoelectric wavefront correctors, the dynamics simulation and optimization method of unimorph piezoelectric deformable mirrors for high dynamic shape control was studied. Firstly, based on the parameterized finite element model of unimorph piezoelectric deformable mirror, an efficient and high-precision electromechanical coupling dynamics simulation analysis method was proposed. Then, through orthogonal traversal of multi-dimensional design parameters (material type, geometric dimension and fixation mode of the optical reflector and piezoelectric ceramic), the influence of different parameters on the dynamic shape control performance of unimorph piezoelectric deformable mirrors was explored. Finally, the optimized design scheme of the unimorph piezoelectric deformable mirror with expected response bandwidth and actuation displacement performance was obtained. The experimental results show that the natural frequency and mirror actuation displacement amplitude of the developed unimorph piezoelectric deformable mirror are in line with expectations, which verifies the effectiveness of the proposed dynamics simulation and optimization method and provides a scientific theoretical method for the efficient development of high-bandwidth unimorph piezoelectric deformable mirrors.