The aging precipitation process and its kinetics of Mg-8Zn-4Al-0.3Mn-xRE alloy were analyzed by metallographic microscopy and DSC, and the results showed that the aging precipitation process of Mg-8Zn-4Al-0.3Mn alloy without RE elements was as follows: supersaturated solid solution→ fine diffusion precipitated phase→ recrystallization softening and aggregation and growth of precipitated phase. The aging precipitation process of Mg-8Zn-4Al-0.3Mn alloy with RE element is as follows: supersaturated solid solution→ fine dispersion precipitated phase→ aggregation and growth of precipitated phase. After artificial aging, compared with the alloy without RE, the peak microhardness of alloy 2, 3 and 4 increased by 5.6%, 9% and 13.4%, respectively. With the increase of RE element content, the activation energy of precipitated phase formation of the alloy gradually increases

TEM, XRD and other analytical methods were used to study the structure of the compound phase in the rapidly solidified Al-Ti-La alloy and the structure after high-temperature annealing, analyze the high-temperature stability of the compound phase, and put forward the twin nucleation theory of the compound phase. Rapid solidification of Al-Ti-La alloy to form fine, round, diffuse intermetallic phase, analyzed as Al20Ti2(RE), diamond cubic structure, the compound phase to form twins, its twin surface {111}, twin direction [112], it is believed that the compound phase is formed and grown with twins as crystal nuclei from the melt preferentially other compound phases.

Considering the structural characteristics of the injection mold (the cavity is a slit surface and the cooling hole is elongated), the boundary integral equation for solving the three-dimensional temperature field of the injection mold is derived through the coupling of boundary equation and boundary gradient equation, and the numerical method for calculating the basic solution integral and the analytical method of high-order singular integral are given. Finally, the application of numerical analysis in cooling system design is illustrated by example.

The bioreactor is the key equipment for the entire biological reaction process. According to the characteristics of the anaerobic reaction process, a new idea of anaerobic reactor with both internal and external circulation systems is proposed. The structure, flow experiment and heat transfer experiment of the reactor were introduced. The experimental results show that after the flow is stable, when the external circulation flow is in the range of 400~1 450 L*h-1, the internal circulating liquid velocity of the reactor increases exponentially with the increase of the external circulation flow, and when jacketed heat exchange, the external circulation flow is in the range of 0~1 300 L*h-1 and the cooling water flow is in the range of 250~750 L*h-1, the heat transfer coefficient increases linearly with the increase of external circulation flow or cooling water flow.

Using the equilibrium method, the solubility of cyanic acid in water was determined, and the data correlated with the Apelblat solubility equation was: lnx=-474.8025+(18 932.949 4)/(T)+70.7514lnT, and the average relative error between the calculated value and the experimental value and the literature value was 1.28%.Using temperature as the input vector and solubility as the output vector, RBF neural network was established, and the results showed that The function approximation of RBF neural network can achieve fast convergence of the network, and the average error of the training set is 0.81% and the average error of the test set is 1.64%.

The pulsating wind speed in the wake area of the two extreme bridge sections was measured by the hot wire anemometer, the Strouhal number was converted by the characteristic size of the model height, and the three-component force coefficient of the model was measured by the balance. Based on this, the relationship between the Reynolds number with beam height as the characteristic dimension and the above parameters is analyzed. The experimental results show that the Reynolds number effect in the blunt bridge section represented by П-shaped beam is small and negligible. The Reynolds number effect in the streamlined section represented by the Nanjing Second Bridge cannot be ignored, and the experimental results show that the three-component force coefficient results given by the traditional low Reynolds number wind tunnel test are conservative.

Pile anchor and soil nail support structure are the two most commonly used deep foundation pit support forms in China. According to the characteristics and design calculation method of soil nail and pile anchor support structure, through the example of a large deep foundation pit project in Zhengzhou City, Henan Province, the force and deformation characteristics of the joint support structure of pile anchor and soil nail and its design calculation method are studied, which has certain reference value for similar projects.

The elastic-plastic stiffness matrix of steel tube concrete bending members is derived by using the finite element method of segmented and block rod structure based on fiber model, and a calculation model for calculating the elastic-plastic stable bearing capacity of steel tube concrete bending members is proposed, and the corresponding calculation program is compiled. The proposed method and procedure were used to calculate the elastoplastic ultimate bearing capacity of the axial compression and eccentric compression long column of steel tube concrete with round pipe cross-section, and the theoretical analysis results were in good agreement with the experimental and theoretical results reported in the literature.

Civil air defense engineering peacetime and wartime function conversion is an important guiding ideology of civil air defense engineering construction and development, civil air defense engineering main structure reinforcement transformation must meet the three indicators of reliability, rapid and economical, post-column technology is the main structure of civil air defense engineering to improve the structural resistance level of more practical method, wooden column is an easy to process and install and economically feasible post-column form. Using the beamless plate structure, the stress-strain relationship and possible failure characteristics of the concrete and steel bars in the concrete and components on the slabs, walls and columns were analyzed by the step-by-step loading test of the water bladder. The test results show that the wooden column can be used for the reinforcement and transformation of the main structure of civil air defense engineering.

Based on the experimental study of two groups of six short limb shear wall (SLW) specimens under low cycle repeated loading, the above test wall was numerically analyzed by nonlinear analysis. The strain distribution law of each specimen shows that the strain distribution of a single wall limb basically conforms to the flat section assumption, and the force performance of the T-shaped truncated interview piece is significantly better than that of the one-line truncated interview piece. The calculation of the internal force when the specimen yields shows that the internal force of the left and right wall limbs is not equal. The comparison of the calculation of the internal forces of different specimens accumulates data for the improvement of the structural design method of this type.

The combination test of two matrix strengths and five volumetric contents of steel fibers was carried out, and the significance of the influence of steel fiber volume content and concrete matrix strength on the continuous energy consumption in a certain deflection interval after improving the ultimate flexural strength and reaching the ultimate bending strength was studied by ANOVA, and the toughening effect of different combinations of steel fiber volume content and matrix strength was compared. The results show that the volume content and matrix strength of steel fiber are significant factors affecting the flexural toughness of steel fiber concrete.

In gray system theory, gray clustering decision is to generate a gray clustering matrix by analyzing and calculating the collected scattered information through the whitening function and gray clustering weights, so as to classify the research objects. Based on the application of gray clustering decision, the application of gray clustering decision in pavement performance evaluation is discussed by taking the performance evaluation of a certain section of highway asphalt pavement as an example.

On the basis of molecular thermodynamic theory, a quantitative correlation model between the separation factor of fullerenes and column temperature, carbon number and mobile phase composition in high performance liquid chromatography was established, and the model was tested with C70 and C60~C96 experimental data from different sources, and the results showed that the model had wide applicability and satisfactory reliability.

The frequency of securities investment Risk describes the frequency of adverse results within a specified period of time, reflecting the urgency of risk negativity. Although people recognize the urgency of negativity in risk measurement, the measurement and control of frequency risk are often limited to qualitative analysis and lack theoretical support. Starting from the analysis of the essential attributes of the frequency risk of securities investment, from a quantitative point of view, by introducing the frequency coefficient, a measurement model of frequency risk is proposed, and the estimation method of frequency risk is given, especially the two estimation methods of frequency coefficient. Finally, it is theoretically proved that by constructing a securities portfolio, the frequency risk can be effectively reduced, which provides a useful reference for the in-depth study of frequency risk.

The construction of the "Digital Yellow River" project aims to realize the information management of the Yellow River and ultimately realize the modernization of the Yellow River water conservancy. Focusing on the three centers of "flood threat, contradiction between supply and demand of water resources, and deterioration of ecological environment", the implementation of the "Digital Yellow River" project is comprehensively driven by seven aspects: flood prevention and mitigation, water quantity scheduling, water quality monitoring, soil erosion control and monitoring, water conservancy project operation and management, e-government and the Yellow River network. The key supporting technologies of the "Digital Yellow River" include geographic information system, remote sensing technology, satellite global positioning system, communication network technology, spatial data (warehouse) database and virtual reality technology." The key to the Digital Yellow River project is the construction of the Yellow River Basin model.

The reconstruction of three-dimensional shapes from a sequence of plane contour lines has a wide range of applications, and the handling of key problems such as positioning and branching in reconstruction directly affects the accuracy and practical value of three-dimensional shapes. The key problems such as branching problem, positioning, smoothness and continuity that need to be solved when using the method are analyzed, and the solution of branching and positioning problem is improved, and it is proposed to transform the multi-branch problem into several single-branch problems according to the perimeter ratio of multiple contours to solve the branching problem and particle alignment for positioning, so as to improve the accuracy of reconstruction.

Based on vector spectrum analysis, an analysis method for two-channel vibration signals - vector power spectrum analysis is proposed. Starting from the basic theory of vector spectrum, the conclusion that the sum of the energy of any two channels perpendicular to each other on the same section of the rotor under each frequency response is a certain value, and the representation method of vector power spectrum analysis is given on this premise, and then the AR model in the power spectrum estimation of the parametric model is used to realize the AR power spectrum estimation of dual-channel data integration. Due to the cumbersome calculation process, a simplified algorithm is proposed, and the processing of the two signals can be synchronized with each other, and finally this analysis method is realized by C++Builder 5.0 programming, and its practicality is verified with actual data.

Since G = L(3,2)SL(3.2), the elements in L(3,2) can be represented as third-order matrices on GF(2). Using fundamental group theory and matrix methods, the GF(3) module decomposition of the group L(2,2) is discussed, and in particular, the decomposability of the GF(3) module of L(2,2) is studied. It is considered that the GF(3) module of L(2,2) can be decomposed into the direct sum of irreducible modes, if V is the extraordinary mode of G and t∈G, o(t)=2 can make V/Cv(t)=2, then V=V1V0, where V1 is the G natural mode and V0=CV(G); If V/CV(G) is a G natural module, then V = V0, where G is irreducible and /C(G) is a G natural module, and | C(G)|≤2,V0≤CV(G

In previous studies on model selection, it is generally assumed that a model is selected, and then the distribution family determined by the model is compared to find the optimal distribution function and numerical characteristics, ignoring the uncertainty of the model itself. The method and application of Bayes method in model selection are introduced, and an example is given to show that using Bayes method to select a model can not only reduce the influence of model uncertainty in model selection, but also extend the model according to the actual situation and the deepening of problem understanding.

Due to the water hammer effect of the water diversion system and the strong nonlinear characteristics of the water turbine, it is difficult to achieve satisfactory results in improving the stability of the power system by using conventional speed regulation control for the hydro generator set. The fuzzy power system stabilizer (FGPSS) on the governor side of hydroelectric generator set was designed based on fuzzy control theory, and its effect was simulated by SIMULINK. The results show that FGPSS can better improve the dynamic performance of the unit and has strong robustness.

Nickel-cadmium batteries have good charge and discharge performance, especially for high-voltage, high-current nickel-cadmium battery packs, it is necessary to design special charging equipment that meets the requirements of charge and discharge characteristics for different charging voltages and discharge currents of nickel-cadmium battery packs. For the heating and overcharge problems in the fast charging of large-capacity nickel-cadmium batteries, a charging method is proposed to superimpose short-term deep discharge pulses during the fast charging process to reduce battery polarization, reduce battery heating, and extend the service life of nickel-cadmium battery packs. The specific process of implementing the method with a single-chip microcomputer, the principle of hardware control system formed by a single-chip mechanism, and the program design idea of software to realize the optimal charging and discharging curve of nickel-cadmium battery were analyzed.

Based on the principle of non-chemical pulping technology of wheatgrass and explosion method, the polysaccharide content in the filtrate of wheatgrass pulp was tested and analyzed, and a livestock animal feed in line with local reality was developed, and comparative feeding was carried out. This technology can not only solve the problem of COD of papermaking wastewater and reduce pulp transportation costs, but also can be used for the preparation of industrial raw materials such as ethanol and gluformaldehyde.

The pyrolysis characteristics of the combustible components of municipal solid waste (MSW) were discussed and analyzed in detail from the aspects of industrial analysis and pyrolysis gas components. From the experimental results, it can be seen that the composition and properties of the combustibles in the garbage are very different, and the direct incineration treatment will inevitably bring difficulties to the design of the incinerator. Pyrolysis combustion treatment technology is a technology that makes it easier and more effective to control the secondary pollution brought by solid waste to the city.

Co-metabolic conversion rate is related to the consumption of growth substrate during the growth period and the consumption of biomass and/or energy substances in the absence of growth substrate. By comparing the three co-metabolic kinetic models (1~3) proposed earlier on dormant cells, the common characteristics of the three models in the presence of high concentrations of growth matrix are obtained, and the expression of non-growth matrix transformation in the presence of growth matrix is proposed, and the equation formed by combining this expression with cell growth expression describes another complete model (4), which covers the characteristics of model 1~3 and is applicable to the co-metabolic dynamics of dormant cells and growing cells. Model (4) describes the transformation of non-growth substrates and the consumption of growth substrates and biomass, predicting that co-metabolism leads to an increase in the amount of substances required for biological growth and the rate of decay as well