Traditional vortex flowmeter has weak adaptability to pipeline environment, small measuring range ratio, and is easily interfered by various noises, so it cannot be applied to harsh industrial environments such as petrochemical and metallurgical environments. An intelligent vortex flowmeter with high accuracy, wide measuring range and strong environmental adaptability was proposed. In hardware design, MSP430 series single chip microcomputer with built-in low-power hard core fast Fourier transform (FFT) multiplier was used as the main control core, and the adaptive band-pass filtering and automatic gain control amplification were carried out on the weak signal output by piezoelectric vortex sensor to obtain a more stable analog frequency signal; the analog frequency signal was digitally collected and calculated to obtain a stable pulse signal related to the actual flow, so as to better overcome the interference of field mechanical vibration and electromagnetic signals, improve the environmental adaptability of the vortex flowmeter, and enhance the comprehensive measurement accuracy of the system. In software design, FFT algorithm was used as an auxiliary method to avoid high frequency signal section and greatly enhance the accuracy of measurement in the case of low flow rate and weak signal. The field test results show that the designed vortex flowmeter runs stably, and the relative indication error and repeatability error meet the standards of the first level meter in the national standard Vortex Flowmeter (JJG 1029—2007), so it has a very wide range of applicability in the measurement of water and gas medium vortex flow under various industrial environments.
The thrust tile plays roles such as supporting the mechanical rotating body and reducing the friction coefficient of the mechanical movement in the large-scale water-turbine generator units. In its running state, the oil temperature and tile temperature are used as monitoring indicators, but the lag of tile temperature monitoring becomes the main factor restricting the safe and reliable operation of water-turbine generator units. An intelligent online monitoring system of elastic metal-plastic thrust tiles was proposed, which integrated key technologies such as sensor, data acquisition, network communication and data fusion, as to form a data analysis and diagnosis model. On the basis of the current standards, by optimizing the installation dynamic acceptance standards and the unit running state standards, the running state of the thrust tiles was judged to make early warnings and diagnosis. Since the intelligent online monitoring system of elastic metal-plastic thrust tiles was put into use in the 1# Hongjiadu Hydropower Station, the force ratio has been in a reasonable range, and the installation and operation of the units are in good conditions. Compared with the traditional thrust tiles and the old standards, the intelligent online monitoring system of elastic metal-plastic thrust tiles can give yellow warnings and diagnosis to the thrust tile failure in the early stage, effectively avoid the failure and shutdown, and meet the concepts such as safety, intelligence and green.
Affected by the particularity of non-load-bearing body, there are many challenges in the mixed-line production of load-bearing body and non-load-bearing body. A processing technological scheme of using automatic guided vehicle (AGV) to realize the mixed-line assembly of chassis of load-bearing body and non-load-bearing body was put forward. Taking a project as an example, the layout of the assembly loop was designed, and the dynamic, split and integral mixed-line assembly processes were adopted to cover the assembly process flow of the load-bearing body and the non-load-bearing body in the same assembly loop. A three-drive four-follow omni-directional wheel structure layout suitable for the assembly process flow was designed, in which the requirements of heavy load assembly were ensured with the help of three-lift design. An innovative locking mechanism of AGV lifting-sliding platform was designed, so that the sliding platform could be locked in the whole lifting stroke, and both X and Y directions could be locked at the same time. The technological difficulties of transferring the AGV loaded vehicles between chassis assembly lines were solved, and the planned production takt of 75 JPH was achieved.
The traditional g-C3N4 photocatalytic materials have some problems such as high recombination rate of photo-generated electrons and holes, low utilization rate of visible light, low quantum efficiency, small specific surface area and large internal resistance. Their photocatalytic performance is poor. By using a series of methods such as calcination and hydrothermal reaction and taking the g-C3N4 nano-sheets as the substrate, different contents of CdS were compounded with the g-C3N4 nano-sheets, and the CdS/g-C3N4 photocatalytic composites with different ratios were prepared by up-conversion and heterojunction construction. Characterizing instruments or methods such as scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet-visible spectrophotometer and BET were used to investigate the composition, micro-morphology, specific surface area and photocatalytic properties of photocatalytic composites. Rhodamine B was regarded as a pollutant, and its degradation performance under visible light was analyzed. It is found that the 7% CdS/C3N4 photocatalytic composites are superior to the 5% CdS/C3N4 photocatalytic composites and the pure g-C3N4 nano-sheets in the degradation of rhodamine B. Such a result show that the mechanism of up-conversion and heterojunction construction can effectively reduce the recombination rate of photo-generated electrons and holes, improve the utilization rate of visible light, and thus improve the photocatalytic rate of materials.
The abundance measurement results of uranium and plutonium isotopes can provide valuable information for the development of nuclear science and the exploitation and utilization of scarce resources, and the ionization emission law has a decisive influence on the accuracy of abundance measurement. Using thermal ionization mass spectrometry (TIMS), the ionization emission law of uranium and plutonium isotopes was studied by controlling the currents of sample zone and ionization zone as well as the amount of sample coating. Findings: when the current of ionization zone and the amount of sample coating are consistent, with the increase of the current of sample zone, uranium isotopes (234U, 235U, 236U and 238U) and plutonium isotopes (238Pu, 239Pu, 240Pu, 241Pu and 242Pu) all show obvious mass fractionation effect, and when the sample is vaporized and ionized from the sample zone, the ratio of the isotopes with small mass numbers is larger than that of the isotopes with large mass numbers. When the coating amount is small, 235U/238U shows higher precision in the TIMS isotope analysis. The relative standard deviations of 239Pu and 235U are 0.003 0% and 0.001 5% respectively under the conditions of 3~5 μg of amount of sample coating, 25~30 min of stabilization time and (1.2~2)×10-11 A of electrical signal, meeting the relative standard deviations of 0.5% and 0.05% in relevant national standards.
Started from the indexes such as chromaticity, acid value, emulsion resistance, rotating oxygen bomb value, paint film tendency index (MPC value), sediment (sludge and n-pentane insolubles), the new turbine oil and the running turbine oil of a power plant were taken as samples, to carry out the open cup aging test and infrared spectrum test, and thus, the correlation between the antioxidant performance and the oxidation stability of turbine oil was judged, and the evaluation indexes of oxidation stability were determined. Findings: all indexes of antioxidant performance are positively correlated with oil aging time and oil oxidation degree; rotating oxygen bomb value and paint film tendency index should be taken as the main evaluation indexes of oxidation stability of turbine oil together with the acid value and sediment mentioned in Glossary on Electric Power Oil (DL/T 419—2015); the precipitated sludge produced after oil aging contains carbonyl compounds and ester-based compounds, so the sludge and other sediments should be removed in time at the initial stage of oil oxidation to avoid the accumulation of aging products and the production of macromolecular sludge.
As a kind of mixed concrete matrix, steel fiber reinforced concrete has a good crack resistance effect when applied to beam structures, but the expression of its cracking and failure mechanism is a difficult point in finite element modeling. A general plastic damage model of concrete was constructed. According to the Sidoroff energy equivalence principle and considering the plastic damage characteristics of concrete, typical plastic damage factors of concrete were deduced, and the plastic constitutive parameters of steel fiber reinforced concrete were defined. The uniaxial inelastic stress-strain curve of steel fiber reinforced concrete which is easy to be iteratively converged and whose numerical value fits the actual situation was obtained. The finite element model was established, the cracking characteristics and bearing capacity of steel fiber reinforced concrete composite beams were investigated, and the separate modeling using random function was carried out, as to demonstrate the feasibility and applicability of finite element modeling of steel fiber reinforced concrete composite beams. It is found out that the established finite element model can be used in post-processing analysis to investigate the cracking and damage of beam structures with different thickness of steel fiber reinforced concrete, and to realize accurately and reliably simulation of steel fiber reinforced concrete composite beams. In a specific trabecular structure with a small number of steel fibers, a certain number of steel fibers can be randomly generated, so that the separated modeling can be realized, and the stress changes of steel fibers can be more intuitively understandable.
Inverter has a wide range of application scenarios, and there is a difficult point in its design to avoid its high-frequency electromagnetic interference and electromagnetic pollution to the electrical equipment. According to the application requirements of vehicle inverter, a sine wave vehicle inverter was designed and implemented. The hardware frame structure with Boost voltage-up circuit and full-bridge inverter circuit as the core was designed. The LC filter was optimized, the series impedance and parallel impedance were calculated, and the system function of low-pass filter was obtained, which made the output waveform closer to the sine wave. The control technology such as voltage differential feedback was adopted, the digital controller SMT32 adopted bipolar SPWM digital control mode to generate the driving control signal, and the PID double closed-loop control adjustment was used to realize the rapid stability of the output voltage. The test on the designed sine wave vehicle inverter is carried out, showing that the output power can reach more than 200 W, the efficiency exceeds 85%, and the total harmonic distortion (THD) value is less than 1% under resistive load and less than 3% under inductive load, which can fully meet the application requirements of various load types of electrical equipment.
The “smart hand” automatic storage robot was built on the embedded platform of Jetson TX2 motherboard, and a binocular camera was installed in the traditional robot hand, so that the target could be captured by the architectural design of the visual system. The binocular camera scanned the spatial layout, and the vision inspection system platform and the line structured light scanning measurement platform completed the path planning in the specified coordinate systems, i.e. the pixel coordinate system, the image coordinate system, the camera coordinate system and the world coordinate system. Convolutional neural network (CNN) was used for visual classification, SSD model was used for training, verification and deployment, and the object recognition under CNN framework was realized. The designs of system circuit and mechanism were carried out. The chassis of the mechanism was equipped with various sensors such as anti-falling, infrared ranging, etc. Through the claw force sensing system, the grasping force of grasping objects was adjusted. Finally, the objects were placed in the designated place to complete the storage work.
Muon detection has the advantages such as wide detection range and wide application field, but its miniaturization, low power consumption and expansibility are challenged by the requirements of field detection. With silicon photomultiplier (SiPM) and scintillator as main components, a set of position sensitive readout electronics system, the core system of Muon detector, was developed. The overall structure design of the system was carried out, and the system was divided into front-end acquisition board, data processing board, main control board and power board. The data processing board played a key role in the logic processing of the system function, and achieved the functions such as digital signal discrimination, voltage stabilization compensation, data reporting, etc., by introducing modular and process designs such as noise reduction, time calibration, temperature reading, temperature-voltage conversion, data framing and data transmission. The actual measurement shows that such a system can stably read out the signal data of 400 channels in two layers, and the temperature coefficient of the temperature-voltage curve is 0.021, which is not much different from the specified value of SiPM bias voltage (0.021 5 V/℃) which varies with temperature, thus realizing the environmental temperature compensation. The system meets the requirements of miniaturization, easy expansibility and strong practicability, and provides a flexible solution for Muon detection.
Under the new situation of high-quality development of the manufacturing industry, the logistics system and the manufacturing industry in Hebei Province have shown new changes. And their collaborative development has shown new features. Taking the statistical data of Hebei Province from 2010 to 2019 as the study basis and the synergetic theory as the basic research method, the evaluation index system of high-quality collaborative development between the logistics system and the manufacturing industry was established, and the measurement analysis was carried out to objectively evaluate the synergy degree between the logistics system and the manufacturing industry. It is found that the collaborative development between the logistics system and the manufacturing industry in Hebei Province has the characteristics of stages: at the end of the first stage (2010—2014), the synergy degree is low, and the order degree of the manufacturing industry is higher than that of the logistics system; at the end of the second stage (2014—2017), the synergy degree reached its peak, and the rise of overall synergy depends on the order degree of the logistics system; at the end of the third stage (2017—2019), the synergy degree decreased slightly. Enlightenments for today: to make a certain prediction on the coordination law of deep integration between the logistics system and manufacturing industry, when the order of one rises, do not neglect the promotion of the other; after the structural adjustment of the manufacturing industry, there will be a long “dormant period”, so it is particularly necessary to effectively shorten such a “dormant period”; Beijing and Tianjin are within the jurisdiction of Hebei Province, so the industrial clusters cannot be connected into pieces or form a competition system in policies, which is a major challenge to the high-quality development of manufacturing industry in Hebei Province.
In order to accurately judge the law of failure of industrial products and obtain a more accurate life of industrial products, the parameter estimation of generalized Pareto distribution under stepwise Ⅰ-type mixed censorship was discussed. The maximum likelihood estimation (MLE) and Bayes estimation of shape parameters in the generalized Pareto distribution were constructed. Bootstrap confidence interval and highest posterior density (HPD) confidence interval of shape parameters were obtained by Bootstrap method and Gibbs sampling method respectively. Monte Carlo numerical simulation method was used to compare the MIE and Bayes estimation effects of shape parameters. Two removal schemes were designed, and the trial calculation by numerical simulation and a case study were carried out. The results show: when the sampling size is small, the average relative deviation of Bayes estimation is below 0.3, which is better than MLE, and while the sampling size is large, the MLE is more accurate; in terms of scheme selection, the scheme with a large amount of removal can save testing cost, and under the same confidence level, the HPD confidence interval is better than the Student-t confidence interval.
In order to study the influences of vibration mixing method on various properties of concretes, the concretes were tested based on the actual project and by taking the control variable method as the research criterion. Based on the experimental data, the influences of vibration mixing process on the workability, mechanical properties and durability (frost resistance) of concrete, as well as the improving effect compared with common mixing method, were investigated. It is found that the performances of concretes by vibration mixing method are obviously improved compared with that by common mixing method. Under the vibration mixing process, the fluidities of concretes with different mix ratios all increase, and the overall slump difference is in the range of 10~15 mm; the vibration mixing process is beneficial to improve the compressive strength of different types of concretes, with compressive strength of C35 ordinary concrete increases by 11.7%, of C40 ordinary concrete increases by 10.8%, of C50 ordinary concrete increases by 8.5%, and the overall gaining effect of about 10%. Under the two mixing processes, with the increase of freeze-thaw cycles, the mass loss rate and the change rate of compressive strength of C40 ordinary concrete show an increasing trend. When the freeze-thaw cycles reach 75 times, the gaining effect of vibration mixing process can reach about 50%. Therefore, in practical engineering applications, it is suggested to select the vibration mixing technology as the optimal scheme to improve the engineering quality of concretes.
Taking the 30202 working goaf facing roadway in Muduchaideng Mine in Erdos deep mining area as the engineering background, the mechanism of rock burst in the goaf facing roadway with hard roof and wide coal pillar was studied through research methods such as theoretical analysis and field measurement, and the prevention technology of rock burst was put forward. Through the layer division of the three loading zones and the analysis on the lateral supporting pressure, the mechanism of rock burst in the goaf facing roadway with hard roof and wide coal pillar was obtained: the thick hard roof strata in the high key strata (delayed loading zone) in the goaf is loaded onto the low hard strata (immediate loading zone) overlaying on the wide coal pillar, forming a cantilever beam structure, which leads to high stress concentration of the wide coal pillar and induces the rock burst. Based on this, the technological scheme of rock burst prevention and control was obtained: cutting off the exposed roof of the adjacent goaf, relieving the pressure source of the section coal pillar, making it fully collapse, and making the coal pillar in a state of “low stress and low disturbance”.