For nano-nylon 6, the effects of process factors such as melt temperature, mold temperature, holding pressure and injection speed on the tensile strength of molded parts with welded and non-welded lines were studied. The results show that the tensile strength of weld-wired nano-nylon 6-injection molded parts is significantly lower than that of pure nylon 6 and weld-free nano-nylon 6-injection molded parts. With the increase of melt temperature, mold temperature, holding pressure and injection speed, the tensile strength of nano-nylon 6 injection molded parts increases. Among the selected process factors, the holding pressure has the greatest influence on the tensile strength of the weld line of the injection molded parts.

Taking the volume rate of steel fiber, steel fiber type, treatment method of recycled coarse aggregate and specimen size as parameters, the influence of steel fiber on the compressive performance of recycled concrete was discussed by comparing it with steel fiber natural concrete. The test results show that the compressive strength of steel fiber recycled concrete is slightly lower than that of steel fiber natural concrete, and the addition of steel fiber can improve the compressive strength of recycled concrete to a certain extent, and the size effect coefficient of the cubic compressive strength of steel fiber recycled concrete is not significantly different from that of steel fiber natural concrete. According to the statistical analysis of the test data, the influence coefficient of milled steel fiber (MF) on the compressive strength of natural concrete is 0.25, and the influence coefficient on the compressive strength of pre-wet water recycled concrete is 0.35, and the reinforcement effect of steel fiber on recycled concrete is better than that of natural concrete.

The concept of pavement maintenance and maintenance decision based on life cycle cost analysis method is introduced, the considerations and analysis process of the method are systematically expounded, the analysis method, cost composition and maintenance effect in maintenance and maintenance decision are discussed, the differences of analysis methods under different investment entities are discussed, maintenance cost, user cost (including wheel consumption, fuel consumption and warranty material consumption) and residual value cost model are introduced, and finally a simple example of life cycle cost analysis method is given.

In order to analyze the temperature stress of the porous concrete base layer of asphalt pavement, a three-dimensional finite element model of asphalt pavement of porous concrete base layer was established. Through numerical calculation method, the temperature field of asphalt pavement of porous concrete base layer was analyzed, and the maximum temperature gradient variation range in each natural zone was proposed. The effects of surface thickness, thickness and modulus of porous concrete base layer and foundation modulus on temperature stress were studied. The calculation results with the same conditions are comparatively analyzed, and the results show that the temperature stress of the base layer decreases with the increase of the surface thickness, increases with the increase of the base layer to the foundation modulus ratio, and increases with the increase of the base layer thickness.

The test was to study the mix ratio of recycled concrete porous bricks by using industrial waste residue as coarse and fine aggregate. The KP1 perforated bricks of reclaimed concrete of A, B and C were made by vibration extrusion molding by orthogonal test, and the compressive strength, shrinkage performance and freeze-thaw cycle tests were carried out according to the method specified in the test method > of < wall bricks (GB/T 2542-2003). The results of the test were evaluated according to the > of < concrete porous bricks (JC 943-2004), and the results showed that the strength grade of class A could reach MU15, and the strength grade of class B and C could reach MU10. The shrinkage performance of perforated bricks is small, the freeze-thaw cycle test results meet the requirements, and the price is low, which can be used as an alternative to clay bricks for masonry structure houses.

Through the test of the stress performance of nine 9 mm×350 mm×200 mm 2200 MPa reinforced concrete eccentric compression columns, the load-deflection curve, load-rebar strain curve, load-concrete compressive strain curve and failure morphology of eccentric compression column were analyzed. The experimental results show that the 500 MPa grade steel bar has good synergy with concrete in the column, and its strength is fully exerted. On the basis of experimental and theoretical analysis, the design value of 500 MPa grade steel bar in concrete column is proposed with the design value fy=500 MPa and the calculation formula of compressive bearing capacity.

Based on the strain consolidation model such as sand wells, considering the change of initial effective stress along the depth, ignoring the influence of well resistance and vertical drainage consolidation, applying the logarithmic relationship between the average pore ratio and the average effective stress, a layered calculation model of nonlinear radial drainage consolidation of sand wells is established, and the analytical solution of radial drainage consolidation under constant load is obtained. Under the action of variable load, the load in the change stage is divided into a series of discontinuous and dramatic loads, and the recursive formula of the effective stress is derived. The results show that the average consolidation degree of radial drainage of the soil layer increases with the burial depth due to the increase of self-weight stress with depth. If the self-weight stress in the entire thickness range is taken as the average, the calculated settlement amount will be small and the radial average consolidation degree will be large.

Based on the plane strain problem, the Druck-Prager yield criterion was used to study the influence of different surface inclination angles on the construction mechanical properties of different construction methods of biased continuous arch tunnels. Through the analysis of the mechanical characteristics of the secondary lining of the tunnel and the force of the middle partition wall, the optimal construction method was determined. The simulation results show that when the ground inclination angle is 5°~15°, it is advisable to excavate the side with a small burial depth first. When the inclination angle of the ground is 15°~30°, if the stability of the middle partition wall can be ensured, it is advisable to excavate the side with a smaller burial depth first; On the contrary, it is advisable to excavate the side with a larger burial depth first; The safety factor of the wall foot of the first excavation cave chamber is small, and attention should be paid to strengthening it during construction.

As a natural polymer material, chitosan (CTS) has certain molecular recognition and chiral recognition functions after modification. Vanillin (3,4-dioxanemethylene-benzaldehyde) was grafted onto the chain of chitosan, and then a novel liquid chromatography stationary phase was prepared by bonding it with silica gel by coupling agent γ-glycidyl etheroxypropyltrimethoxysilane. The grafting rate of vanillin grafted chitosan (VCTS) was prepared, and the molecular weight was determined. Vanillin-grafted chitosan (VCTS) was then used as the raw material for the reaction to prepare the bonded silica gel stationary phase (VCTS-KH560-Si), and characterized by Fourier transform infrared spectroscopy, thermal analysis and mass analysis to prove that the bonding products were stable. The separation properties of chiral substances were studied, and the separation effects were discussed

The melting point, heat of melting, decomposition temperature and other properties of trans-ferulic acid were experimentally studied by differential scanning calorimetry and thermogravimetric analysis method, and the conditions for the determination of trans-ferulic acid by DSC-60 differential scanning calorimeter were determined, that is, under the conditions of a heating rate of 10°C·min-1 and a nitrogen flow rate of 20 mL·min-1, the sample could be analyzed to obtain a more accurate DSC curve, and under these conditions, the melting point of trans-ferulic acid was 174.64 °C and the heat of melting was 150.00 J·g-1. The decomposition temperature was 190 °C. Under the condition of nitrogen atmosphere, the DTA-TGA spectrum of ferulic acid was determined by DTG-60 differential thermal-thermogravimetric analyzer, and there was significant weight loss between 190 °C and 260 °C, which confirmed that ferulic acid began at 190 °C in nitrogen atmosphere

Volatile fatty acids (VFA) are important control indicators for anaerobic fermentation reactions, and it is necessary to determine an accurate, precise, simple and fast test method. In the experiment, GC-122 gas chromatograph, N2000 chromatography workstation, organic carrier 402 as packing material, and FID as detector were used to determine the VFA in the anaerobic fermentation broth sample after formic acid pretreatment under the conditions of column temperature of 200°C and carrier gas (N2) flow rate of 52.0 mL/min. The results show that the separation effect of this method is good, the recovery rate of each component is between 94%~108%, the coefficient of variation is less than 3%, the repeatability is good, and the test time is short.

The nano-inorganic composite powder was dispersed in acrylic resin to prepare infrared reflective coating with thermal insulation, and coated on the glass substrate, and the thermal insulation effect was detected by a self-made detection device. Several main factors such as coating film thickness, nanocomposite powder addition and dosage were investigated on the thermal insulation performance of coatings. The results show that the addition of nano-powder plays an important role in the heat insulation of the coating, and the coating prepared after adding the powder has obvious thermal insulation effect, and the heat insulation effect is enhanced with the increase of powder addition within the scope of experimental research. Simulation experiments show that the heat insulation coating can reduce the indoor temperature by 9°C compared with ordinary coatings.

An ultrasonic humidifier that can be applied to small devices or laboratories to regulate humidity, which humidifies by humidifying the oscillator excitation to produce uniform mist water particles with a diameter of several microns. After analyzing the working process of the humidifier, the dynamic mathematical model of humidifier humidification was derived according to the principle of mass balance, and the dynamic performance simulation and experimental analysis of a specific device were carried out. The results show that the step response time constant simulated by the dynamic mathematical model established in this paper and the relative humidity of the humidifier outlet under different duty cycles are close to the experimental results, which can better reflect the humidification process in the humidifier. In addition, simulation and experimental results also show that the humidification device can control the humidity of the outlet within a wide range according to the different working time cycles of the humidifier.

Flange, gasket and bolted connection system are important contents in the design of pressure vessels and pipelines, and are also the key parts that are prone to problems in the process of engineering design and use. Due to the engineering application needs, the non-standard pipe flange, gasket, bolt and valve connection system with a nominal diameter of 450 mm were designed, and a new gasket covered by expanded graphite and 0Cr18Ni10Ti was developed. At the same time, considering the influence of flange rotation and internal pressure on the force and deformation of flange, gasket, bolt and valve, the three-dimensional finite element technology is applied to analyze the overall stress distribution of the flange connection system in the bolt pretensioning process and the pressurization process. The results show that the stress strength of flanges, bolts, etc. meets the requirements, and the gasket stress and residual compression pressure meet the density

At present, there is no absorption tower structure design code in China, and by analyzing the relevant specifications of domestic thin-walled tower structure, it is concluded that the dynamic characteristics calculation method of thin-walled tower structure is basically reduced to two categories: only considering the structure itself and only considering the solid-liquid coupling effect. According to the finite element theory, the structure of flue gas desulfurization absorption tower with high tower is modeled by finite element and dynamic characteristics are analyzed, and the stiffness distribution is deeply understood. By comparing the results of finite element analysis with the calculation results according to the formulas in the structural specifications of various thin-walled towers in China, it is concluded that the basic self-vibration period of the absorption tower structure can be calculated according to the formula in the > of < steel tower vessels, with an error of 4.5%.

In order to obtain the influence of various parameters on the bit error rate of MIMO system under Nakagami-related fading, a new MIMO-OFDM system model is first given. Then, the channel bit error rate of the spatially correlated MIMO-OFDM system based on STBC coding under the flat fading of Nakagami-m is studied, an expression of bit error rate is given, and the influence of spatial correlation and distribution parameters on the bit error rate of the system is analyzed. Finally, the bit error rate performance simulation of STBC under space-dependent conditions is given to verify the effectiveness of the theoretical analysis. The results show that when neither the Rayleigh nor the Rice distribution is sufficient to describe the channel characteristics, the Nakagami distribution is used to compare the actual measured data, and the channel fading is based on Na

A distributed denial-of-service attack (DDoS) detection algorithm suitable for mobile Ad Hoc networks is proposed, and the Kolmogorov complexity estimation algorithm based on sequence analysis is improved. The new algorithm analyzes the flow in the network and calculates the complexity of the sequence feature set, and detects distributed denial-of-service attacks through the complexity analysis. Simulation results show that the false detection rate and detection time of the proposed algorithm are better than the traditional complexity estimation algorithm.

An adaptive color image watermarking algorithm based on space-time chaos in the discrete cosine transformation domain (DCT domain) is proposed. The algorithm uses the spatiotemporal chaos model to generate chaotic sequences to scramble and encrypt the binary watermark, and determines the watermark embedding intensity by combining the improved human vision model (HVS) image block classification method and the RGB component characteristics of color images, and finally the watermark is repeatedly embedded in the DCT intermediate frequency transformation coefficient of each component of the color image RGB. Experimental results show that the algorithm has very good robustness against various noise, filtering and compression attacks, and watermarks with similarity of 30.25 and 0.914 can still be extracted when subjected to attacks with a compression ratio of 0% and a shear of 869%, respectively.

According to the theoretical analysis of the influencing factors of power consumption and engine output power of cold milling machine, the working speed of the machine was selected as the power adaptive control parameter. On this basis, a simulation model of the system is established, and the use of engine power and its operation efficiency before and after using the adaptive control system are simulated and verified. The results show that it is reasonable and effective to select the machine operation speed as the power adaptive control parameter. The power adaptive system can automatically adjust the machine to work near the rated power of the engine, which improves the rated power utilization rate and operating efficiency of the machine by more than 10.2% and 6.32% respectively under the given conditions. This study provides a reference for rational use of engine power and improvement of machine operation efficiency.

The influence of common faults of electronically controlled engine oxygen sensors on engine emissions and conversion efficiency of three-way catalytic converters was studied on the engine fault simulation test bench. The results show that if the oxygen sensor is disconnected, the fuel injection pulse width and emission of the engine remain basically unchanged for the idle condition. For common working conditions, the power of the engine increases slightly, fuel consumption increases more, CO and HC emissions increase, and NOx emissions decrease. If the exhaust hole of the oxygen sensor is blocked, the performance change of the engine is similar to the disconnection fault of the oxygen sensor. The concentration of exhaust pollutants before and after the three-way catalytic converter can be detected separately, and the performance of the three-way catalytic converter can be judged. Under common working conditions, if the conversion efficiency of the three-way catalytic converter is low, the three-way catalytic converter is replaced by replacing the new oxygen sensor

Aiming at the structural control problem under earthquake excitation, an instantaneous optimal predictive control algorithm is proposed, which comprehensively considers the influence of displacement, control force input energy and seismic wave energy on the structure in the control process, which solves the problem that the traditional open-loop control must know the external disturbance information in the whole process, and uses the fine integration method to solve the exponential matrix in the control process to avoid solving the eigenvalues and eigenvectors of the dynamic state matrix. The calculation of the exponential matrix in the algorithm is simplified, and the calculation efficiency is improved, so that the algorithm has the advantages of high efficiency, high precision, insensitivity to step size, and unconditional convergence. In the example, the method in the paper is compared with the LQG algorithm, which proves that the effectiveness of the proposed algorithm is better than the LQG algorithm.

Combined with the structural characteristics of rigid arch bridge, ANSYS is used to establish its spatial structure analysis model, using the deflection method to find the lateral distribution coefficient of the load at each calculation point, and drawing various charts according to the calculation results, the results show that the transverse distribution coefficient of the load of the rigid arch bridge has different longitudinal and transverse changes along the longitudinal and transverse laws of the bridge, and when a single transverse load transverse distribution coefficient is calculated, it will have a large deviation from the actual situation. The basic value principle of the transverse load distribution coefficient in the simplified calculation of rigid arch bridge is summarized: the transverse distribution coefficient of the span load of the secondary side arch piece can be calculated by taking the solid abdominal section beam and the middle abdominal hole beam and the main arch leg (including arch foot). The lateral load distribution coefficient obtained by the middle arch support point and the lever principle method can be safely calculated by the side ventral beam.

A set of vectors is introduced, the definition of Jennings composite sequence is newly derived by the method of truth value description, and the proof of the theorem of period and linear complexity of the sequence is simplified and supplemented. In order to measure the stability of the sequence, the weight complexity WCk(u∞) is introduced, and its lower limits of 1-weight complexity and 2-weight complexity are given. When 1=k

Aiming at the heavy metal cadmium pollution accident in the Beijiang River Basin in December 2005, a one-dimensional river heavy metal migration and transformation model was established, and the parameters of the model were determined and verified by combining the measured data of the pollution accident. From the calculation results, when the cadmium concentration value in the water body is large, the calculated value of the heavy metal model fits well with the measured value, while when the cadmium concentration value is low, the fitting effect is not ideal, in addition, the cadmium concentration in the water body decreases from upstream to downstream with the movement of the water flow, which indicates that the heavy metal is gradually deposited in the bottom mud under the action of adsorption and sedimentation.

The "chimney effect" is a general principle that regulates the natural ventilation of the interior space of a building. This paper explains the basic principles of the "chimney effect" in architectural design and the factors influencing architectural design based on this principle: seasonal factors and environmental factors. Combined with examples of contemporary architecture, the specific design patterns and methods of applying this principle are summarized: patio atrium, solar chimney, breathing double-layer curtain wall and environmental wind tower. The breathing double-layer curtain wall is a design mode that reduces the pollution of the outside air to the interior and avoids air turbulence through this principle. The discussion of the "chimney effect" aims to play a beneficial role in saving resources and reducing environmental load.