盒子（公司）

Biocoal is a fossil- free reductant in metallurgical processes. Due to the increasing use, risks associated with selfheating needs to be better understood. In this work, the apparent activation energy and reaction kinetics of a commercial biocoal were investigated using isothermal calorimetry, differential scanning calorimetry, thermogravimetric analysis, and basket heating tests, including the crossing-point method. The derived kinetic parameters were subsequently used to estimate critical storage volumes at 50 degrees C using both the Frank-Kamenetskii theory and a numerical model based on a global apparent reaction-rate expression. The results demonstrate that the activation energy depends strongly on temperature and reaction progress, exhibiting distinct kinetic regimes. At temperatures relevant for self-heating, activation energies obtained from isothermal calorimetry and the crossing-point method were substantially lower than the 87-90 kJ mol(-1) assumed in the N.4 test method for goods classification. As a consequence, the UN N.4 test for classification of goods classified the biocoal as non-self-heating, while both Frank-Kamenetskii theory and the numerical model predicted thermal runaway for container-scale storage volumes. The study highlights that reliance on the fixed activation-energy assumption in the N.4 procedure may lead to false-negative classifications. Recommendations for improved testing strategies are proposed, including multi-temperature calorimetric measurements, clearer definitions of the crossing-point temperature, and consideration of extent of reaction-dependent reaction rates. The findings support recent regulatory actions to classify biocoal as self-heating for maritime transport and underscore the need for revised standards to ensure its safe handling and storage.

PurposeThis paper investigates how farm advisers can develop their practices beyond facilitating farmers' legal compliance to mediate between farmers' and regulatory officials' knowledge and experience of implementing farm-level legal regulation.Design/methodology/approachBuilding on theories of knowledge types and Communities of Practice (CoP), the paper employs a qualitative research design to examine a project aimed at reducing the regulatory burden on farmers, run by advisory organisations in Sweden.FindingsThe studied project developed a four-step method for identifying and processing suggestions for simplified farm regulation. Through internal knowledge sharing, integrating external knowledge, negotiating agreements, developing work models and using their own creativity, they produced and presented proposals to regulatory authorities.Practical implicationsThe study provides a framework for supporting farm advisers in developing their practices by serving as mediators between farmers and regulatory authorities. Implications for policymakers relate to formulating new legislation and updating existing legislation.Theoretical implicationsThe paper refines the understanding of how farm advisers can develop their practices of mediation and knowledge brokerage through CoPs.OriginalityThe paper addresses a key aspect of advisory work - knowledge brokerage - and highlights a new role for advisers as mediators of the knowledge regarding farm-level regulatory issues held by farmers and authorities.

In this work, the undenatured type II collagen (C-II) with an intact triple helix structure was obtained from chicken breast cartilage by the enzymatic extraction method. The self-assembly kinetics of C-II at different parameters of concentration, pH and temperature was characterized by ultraviolet-visible spectroscopy (UV-vis). It occurred at pH 4.5-7.0 and was promoted by rising concentration and temperature in a certain range, and conformed to the first-order dynamics equation. The activation enthalpy (Delta H = 55.76 kJ & sdot;mol- 1) and entropy transition (Delta G = 69.30-71.40 kJ & sdot;mol- 1) revealed that the self-assembly of C-II was a non-spontaneous heat absorption process. It was observed by atomic force microscopy (AFM) that, regulated by concentration, pH and temperature, the C-II self-assemblies displayed diverse nanostructure, such as protofibrils, proto- and nanofilaments, nanofibrils of varying thickness and dense degree. Based on the results of circular dichroism (CD) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), the C-II self-assembly was mainly triggered by hydrophobic effects driven by a partial transition of the left-handed polyproline II (PP II) conformation, and both hydrogen bonding and electrostatic interactions were also involved in the self-assembly process. These results would lay the theoretical foundation for the fabrication and application of controllable C-II self-assemblies.

Abstract The conventional compressive sensing (CS) based on the ℓ1-norm can reconstruct the azimuthal modes for the rotating flow in compressors when the data are undersampled spatially. However, the signal noise and outlier can greatly affect its accuracy. The present work presents the application of the Bayesian compressive sensing (BCS) in the azimuthal mode reconstruction for the rotating flow in a transonic fan. To improve the anti-outlier ability during the mode reconstruction, a heterogeneous noise model (HNM) is introduced to consider the signal outlier encountered at some specific probes. Mode reconstructions for the azimuthal components with different undersampling ratios are carried out to examine the performance of the above methods. It is found that the signal outlier can reduce the dominant mode amplitude and result in the formation of aliasing modes for the BCS and the conventional CS methods. In contrast, the BCS-HNM method can accurately identify the dominant mode order and further recover the mode amplitude in the presence of amplitude or phase outlier. If the undersampling becomes severe, the overall accuracy tends to deteriorate for all the three methods. However, the BCS-HNM still exhibits the highest probability to achieve a successful mode reconstruction and finds the probes with signal outlier. The robustness of the BCS-HNM has also been demonstrated, and it is revealed that the performance of the BCS-HNM method can be maintained over a wider range of signal outlier compared to the other two methods.

To investigate the effect of fuel rod bending on coolant flow and heat transfer in lead-cooled fast reactors, the CFD models of C-shaped bending fuel assembly are established in this paper. Results show that fuel rod bending reduces heat transfer efficiency by 2.1 %, 5.4 %, and 7.4 % under Cases 1-3, respectively. Compared with the normal condition, the coolant velocity in corner and edge subchannels on the bending side decreases, with the maximum temperature rises reaching 11.12 K and 13.5 K under Case 3, respectively. On the bending dorsal side, the coolant velocity in both corner and edge subchannels exceeds the LFR design limit of 2 m/s under Cases 2 and 3. Bending also amplifies the deformation of fuel rods under fluid load, causing stress concentration on the 15th corner rod, the maximum deformation rises by 0.069 mm and the von Mises stress by 2.04 MPa under Case 3.