Search

The new version of the gear accuracy standard GB/T 10095.1—2022 has been released, and the standard of accuracy of rack is written with reference to the gear accuracy standard. The manufacturing technology and the processing accuracy of racks have changed greatly, so the standard of accuracy of rack has been revised. The main differences between the 2022 version of the standard of accuracy of rack and the 1988 version are: terms and symbols; definition of total tooth profile deviation; measurement of the rack pair; adding the parts detection method of flame cutting large modulus racks for lifting and lowering of offshore platforms, as well as five measurement tools that can be used in the production process of racks. Analysis is conducted concerning the added and the revised parts.

BackgroundThere is usually a strong coupling of neutronics-thermal hydraulics (N-TH) fields inside nuclear reactors.PurposeThis study aims to accurately simulate the multi-physics fields in nuclear reactors by developing a three-dimensional N-TH coupling code MORPHY tailored to advanced complex reactors.MethodsFirst of all, a three-dimensional triangular-z nodal variational nodal method (VNM) was employed for neutronics calculation. and the stiffness confinement method (SCM) was used to solve the neutron temporal-spatial equation; thermal hydraulic calculations were based on the one-dimensional multi-channel model and the one-dimensional cylindrical thermal conductivity model. Then, the accuracy of neutron dynamics was verified by TWIGL benchmark, Dodds benchmark, and the typical pressurized water reactor (PWR) benchmark NEACRP. Finally, the effects of different coupling methods and angle discrete orders on the results were analyzed and compared against reference solutions by PARCS.ResultsVerification results of TWIGL benchmark show that the deviation of relative power from the reference results is less than 0.5%. Compared with the results of Dodds benchmark, it verifies the MORPHY code's ability to describe unstructured meshes. The transient coupling calculation capability of MORPHY is verified by NEACRP benchmark.ConclusionsNumerical solutions by MORPHY are in good agreement with reference results of the TWIGL, Dodds and NEACRP benchmark problems. It is concluded that MORPHY can adapt to the transient N-TH coupling analysis of nuclear reactor cores.

BackgroundWith the improvement of the understanding of the physical mechanism of neutron transport and the development of high performance computing technology, high-fidelity neutronics calculation has attracted widespread attention worldwide. Both deterministic method and Monte Carlo method are employed by various institutions to achieve high-fidelity goals. NECP-X code uses one-step deterministic method whilst OpenMC uses the Monte Carlo method.PurposeThis study aims to verify the feasibility and accuracy of both NECP-X and OpenMC in modelling high-fidelity reactor cores.MethodsBased on BEAVRS2.0.1 benchmark, two high-fidelity models for pressurized water reactor (PWR), i.e., MODEL 1 consisted of 21 fuel assemblies and MODEL 2 consisted of 193 fuel assemblies, were established. Then, NECP-X (one-step deterministic method) and OpenMC (Monte Carlo method) were respectively adopted in these two high-fidelity models to calculate the effective multiplication factor, the reactor power distribution and the control rod worth of different control rod assemblies inserted in the hot zero power (HZP) condition. Finally, calculated results were compared and analyzed.ResultsUnder the HZP condition, the effective multiplication factor deviation between NECP-X and OpenMC is less than 1.40×10-3. The effective multiplication factor deviation of different control rod assemblies inserted is less than 5.9×10-4, and the deviation of control rod worth is less than 4.9×10-4. The average relative deviations of the reactor power distribution between NECP-X and OpenMC are less than 0.6%.ConclusionsNumerical results calculated by two different codes are in good agreement with each other. The feasibility and accuracy of NECP-X and OpenMC in high-fidelity reactor core modeling are preliminarily verified in this study, which lays a foundation for future applications and improvements.

Thermally enhanced anoxic biodegradation is emerging as a promising method for removing PAHs from soil, but some PAHs remained in the soil after thermally enhanced bioremediation due to low bioavailability of PAHs. Surfactants can improve the bioavailability of PAHs, but the effect of surfactants on microorganisms and the biodegradation of PAHs is unclear under high temperature. In this study, the effects of surfactant Tween 80 on the desorption of PAHs, indigenous micro organisms and anoxic biodegradation of PAHs in deep soils were investigated under thermally enhanced conditions (50 ). The results showed that he desorption of PAHs in soil increased as surfactant concentration increased. After 120 d of anoxic incubation, the addition of low concentrations of Tween 80 (300 and 800 mg/L) increased the abundance of potential degrading bacteria of PAHs in soil by 0.19-1.96 times compared to the control, and promoted the anoxic biodegradation of PAHs. Three - and four-ring PAHs degradation rates increased by 8.56%-16.61% and 5.56%-15.41%, respectively, relative to the control treatment. The addition of high concentrations of Tween 80 (2 000, 5 000 and 10 000 mg/L) reduced the abundance of potential PAHs degrading bacteria in the soil by 61.11%-80.64% compared to the control soil, and inhibited PAHs degrada tion, with 12.45%-38.96% and 26.72%-38.60% reduction in three - and four-ring PAHs degradation rates relative to the control treatment, respectively. And the degree of inhibition increased with the increase of Tween 80 concentration. [ABSTRACT FROM AUTHOR]

[Purpose/Significance] Information ecology, as a kind of overall scenario of user information interaction behavior, reveals the basic logic of information flow among information elements in a particular environment. The study of information ecology in traditional information environment has been relatively mature. With the arrival of the metaverse, its characteristics of virtualization, immersion and decentralization have transformed user information interaction behavior, which in turn has brought about changes of the ecological interaction mechanism. We need to analyze the ecological mechanism of information interaction in the metaverse environment, in order to provide reference for relevant information theory research and promote the birth of metaverse informatics. [Method/Process] This paper stands on the information ecology perspective, takes the four ecological elements of information people, information, information environment and information technology as the entry point, and divides the information interaction ecology under the metaverse environment into three layers of architecture: information interaction, information data and information technology. Among them, the information interaction layer contains information users and information environment. Unlike the information ecological chain, each information user in the information interaction ecology under the metaverse environment is an integration of information producer, transmitter and consumer. Unlike the linear information flow in the information ecological chain, the information flow in the metaverse will show a wave-like diffusion. The information data layer provides the information resources in the information interaction ecology, and in this layer, we discuss the process from production to management of information resources under the metaverse environment. The information technology layer is the implementation path and basic support of the whole information interaction ecology, and in this layer we introduce several information technologies commonly used in the metaverse information interaction ecology. Through the above three-layer architecture, we have discussed the ecological composition of information interaction, information interaction logic, and information movement process as a whole to constitute the user information ecological mechanism under the metaverse enviornment. [Results/Conclusions] This paper constructs an ecological mechanism of user information interaction in the metaverse with a hierarchical architecture from the physical environment to the interaction scene, and provides strategies for the development of this mechanism from the perspectives of user, resource, technology, and governance. Taking the metaverse as the theoretical background, this study re-examines and expands the traditional information ecology theory, with the aim to provide a boost to the development of metaverse informatics. It is worth stating that the ecological mechanism of metaverse information interaction proposed in this paper is a theoretical prediction based on existing research, and the empirical conditions are insufficient. [ABSTRACT FROM AUTHOR]

The deposition of corrosion products in the core causes CRUD (corrosion related unidentified deposit) induced power shift and CRUD induced localized corrosion, threatening the safety and economy of the reactor. Zinc addition is regarded as a widely used method to effectively alleviate corrosion product deposition in reactor core. Despite the wide spread use of zinc, the understanding of mass balance, thermodynamic equilibrium and kinetic substitution of zinc in the primary circuit is still not clear. This paper focuses on the balance and thermodynamic kinetic behaviors of zinc in the primary circuit from the perspectives of theoretical mechanism and numerical calculation analysis. A mass balance model of zinc in the primary circuit was established to evaluate the addition, removal, deposition, precipitation and substitution of zinc in the primary circuit. The thermodynamic equilibrium and substitution kinetics of zinc in coolant were also evaluated. Theoretical analysis shows that zinc in the coolant is involved in hydrolysis and chemical reactions with iron, nickel, silicon and other elements. Zinc mainly exists in the form of zinc hydroxide under the prototypical conditions of coolant water chemistry. When zinc replaces the iron and nickel elements in the oxide corrosion layer, it tends to replace the divalent ions at the tetrahedral positions in the normal spinel, and the ability of zinc to replace the divalent ions in the inverse spinel needs to be evaluated in combination with the hydrolysis and chemical equilibrium of zinc. Numerical analysis shows that the mass balance prediction results of the model are in good agreement with the observation value from Diablo Canyon 1 reactor plant. Gradually reducing zinc addition amount is an effective means to maintain the zinc concentration in the specific optimal range. Zinc addition can effectively alleviate corrosion release up to about 50% and the thickness of CRUD deposition after zinc addition is 42% of that before zinc addition. This study can provide theoretical support to develop the optimal zinc addition technique.

The unique crystalline structure and strong covalent bonding of TiB2 coating give it ultra-high hardness and chemical stability, but it also suffers from poor toughness and weak bonding with metal substrates. Herein, Ni-doped TiB2 coating was prepared by combining high-power pulse magnetron sputtering technology and radio frequency magnetron sputtering technology. Additionally, SEM, EPMA, XRD, XPS, nanoindentation instrument, scratch tester, high-temperature friction and wear testing machine were used to comparatively study the micromorphology, chemical composition, phase structure, mechanical properties, and tribological properties of TiB2-Ni coatings with different Ni contents. Results showed that the Ni-doped TiB2-Ni coating possessed a small amount of Ni element solidly dissolved in the TiB2 lattice, and the excess Ni element existed in the form of a metallic phase, forming a nanocomposite structure at the grain boundaries, which restricted the growth of TiB2 grains, and caused the refinement and nanometerization of the columnar grains of the coating. Besides, the Ni doping brought about a significant decrease in the hardness and elastic modulus of the TiB2 coatings. With the increase of the Ni content, the adhesion strength between the coating and the substrate and the toughness of coatings continuously increased, while the friction coefficient of the coating decreased first and then increased. Moreover, the wear morphology indicated the wear of the coating belonged to abrasive wear and adhesive wear. In conclusion, Ni doping improved the toughness of the TiB2-Ni coatings by generating Ni metal phase in the grain boundaries, which could absorb the fracture energy through deformation during crack expansion. The TiB2-Ni coating with a Ni content of 4.9% (atomic fraction) exhibited good hardness and toughness.

In order to evaluate the accuracy and reliability of the subchannel code, it is necessary to quantitatively give the uncertainty of the calculation results. The uncertainty analysis is conducted by using the statistical method based on propagation of input uncertainties, and the uncertainty range of the subchannel code calculation results can be obtained quantitatively. Based on the assumption that the uncertainty of model parameters obeys normal distribution, the statistical method is used to determine the distribution of the uncertainty of model parameters to replace the traditional expert judgment. Through the calculation of the pressurized water reactor sub-channel and bundle tests (PSBT) benchmark, the ability of the subchannel code COBRA-IV to predict the experimental results is analyzed, and the uncertainty interval satisfying the tolerance limit of the calculation results is obtained. The results demonstrate that the experiment data is well enveloped by the obtained uncertainty bands and the model calibrated by the statistical mean value presents a good improvement of calculations.

Objective: To study the epidemiological and molecular characteristics of Campylobacter jejuni in poultry in Hubei province, we used multilocus sequence typing method to classify 47 local C. jejuni strains., Methods: Genomic DNA of each isolated strain was extract, seven housekeeping genes including aspA, g1nA, g1tA, glyA, pgm, tkt and uncA were amplified by PCR and sequenced, and then the sequences of genes were analyzed using MLST database., Results: There were a total of 38 sequence types and 10 clonal complexes, and ST353 and ST464 complexes were the largest amount of the population of C. jejuni analyzed, of which 2 new allelic profile and 25 new sequence types were found. Phylogenetic tree shows that sequence types from different types of poultry and different regions were different., Conclusion: Forty-seven C. jejuni strains isolated from poultry in Hubei were analyzed using MLST and showed abundant genetic diversity, it will provide scientific data to the epidemiological investigation of C. jejuni in Hubei, China.