Heat Dissipation Characteristics of IGBT Module Based on Flow-Solid Coupling

With the increase of power level and integration in electric vehicle controllers, the heat flux of the key silicon-based IGBT (Insulated Gate Bipolar Transistor) device has reached its physical limit. At present, third-generation semiconductor devices including SiC MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistor) are gradually replacing the dominant IGBT module. The hybrid IGBT module consists of both and can improve the performance and reduce the cost of controllers. Limits due to the installation space, location, and other conditions in the car make it difficult to meet the requirements of controllers with an air-cooled heatsink due to their large size and limited heat dissipation capacity. A smaller and more powerful water-cooled heatsink case is required to ensure the heat dissipation of the IGBT in the controller. Based on previous experience in finite element numerical simulation, hydrodynamics calculation, and heat transfer calculation, ANSYS Workbench finite element software was used to analyze the thermal resistance of each structure inside the module and the heatsink structure. The fluid characteristics and heat transfer performance of three different flow channel structures were analyzed, and the design of the cooling flow fin was improved to provide a reference for the heat dissipation of the hybrid IGBT module

Performance of feeding Artemia with bioflocs derived from two types of fish solid waste

The production of bioflocs with the solid waste from recirculating aquaculture systems (RAS) and feeding Artemia results in additional nutrient retention and lowers waste discharged from RAS. The solid waste from the drum-filters of two RAS, which stocked European eel (Anguilla anguilla) and Nile tilapia (Oreochromis niloticus), was used as substrate to produce bioflocs in suspended growth reactors, referred to as E-flocs and T-flocs, respectively. Mono-diets consisting of 100% E-flocs and 100% T-flocs were added to culture Artemia, referred as E-Artemia and T-Artemia, respectively, in a laboratory scale test. The efficiency of this feeding regime was investigated. A significant difference was observed in terms of crude protein content (35.59 ± 0.2%) for E-flocs, (29.29 ± 0.95)% for T-flocs, (70.01 ± 0.92)% for E-Artemia and (65.63 ± 0.89)% for T-Artemia. 134 out of the total operational taxonomic units (OTUs) were present in E-flocs and T-flocs from the analysis of high-throughput sequencing data. Most of the shared OTUs belonged to cyanobacteria. C18:1n7 of T-flocs was higher than that of E-flocs (P 0.05). The survival rate of E-Artemia was (22 ± 0.02) %, significantly higher than that of T-Artemia (16% ± 0.02%) (P 0.05). The EPA of Artemia fed with E-flocs was (3.00 ± 0.46)%, significantly higher than that of T-Artemia (1.57 ± 0.19%) (P < 0.05). This study offers a method for reusing the aquaculture waste, which will be helpful to achieve a zero-pollution discharge for aquaculture systems. Keywords: Bioflocs, Fish waste, Artemia, Recirculating aquaculture system, Suspended growth reactor

Research on Heat Dissipation of Multi-Chip LED Filament Package

By studying the substrate material, structure, chip distribution, and array form of the multi-chip light-emitting diode (LED) package, the heat-dissipation capacity of the LED package is improved. Finite element analysis and steady-state thermal analysis are used to simulate and analyze LED packages with different materials and structures. Using the theory of LED illuminance and uniformity, the illuminance of some structures is computed. The results show that the change of substrate material and structure can greatly impact heat dissipation, while changing array forms has little effect on heat dissipation. By improving the spatial distribution of the chip, the temperature superposition problem of the substrate is solved, and the illuminance and uniformity are improved while dissipating heat. The LED filaments of the combined, equidistant, chip-distribution mode have improved heat dissipation. The S-type equal difference has the highest illumination and high illumination uniformity

Heat Dissipation Characteristics of IGBT Module Based on Flow-Solid Coupling

With the increase of power level and integration in electric vehicle controllers, the heat flux of the key silicon-based IGBT (Insulated Gate Bipolar Transistor) device has reached its physical limit. At present, third-generation semiconductor devices including SiC MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistor) are gradually replacing the dominant IGBT module. The hybrid IGBT module consists of both and can improve the performance and reduce the cost of controllers. Limits due to the installation space, location, and other conditions in the car make it difficult to meet the requirements of controllers with an air-cooled heatsink due to their large size and limited heat dissipation capacity. A smaller and more powerful water-cooled heatsink case is required to ensure the heat dissipation of the IGBT in the controller. Based on previous experience in finite element numerical simulation, hydrodynamics calculation, and heat transfer calculation, ANSYS Workbench finite element software was used to analyze the thermal resistance of each structure inside the module and the heatsink structure. The fluid characteristics and heat transfer performance of three different flow channel structures were analyzed, and the design of the cooling flow fin was improved to provide a reference for the heat dissipation of the hybrid IGBT module

The enhancement effect of Nb over CeSi2 catalyst for the low-temperature NH3-SCR performance

Tuning the acid site on the surface of the catalyst tends towards facilitating the selective reduction of NOx by NH3 (NH3-SCR). In this study, a set of catalysts for the Nb/CeSi2 with different loadings of niobium were synthesized and evaluated in terms of NH3-SCR over a broad temperature range. The results indicated that a catalyst for 20Nb/CeSi2 exhibited the best low-temperature NH3-SCR performance while maintaining excellent SO2/H2O resistance. These catalysts were also characterized by BET, XRD, Raman, NH3-TPD, and H2-TPR to further explore the correlations between catalyst structure and performance after adding niobium. For the Nb/CeSi2 catalysts, the surface structure was blocked by niobium species, resulting in varying degrees of reduction in the specific surface areas. Also, the total acidity decreased with the declines of the specific surface areas while the acidity per unit was enhanced, which facilitates the occurrence of the SCR reaction. Furthermore, in situ DRIFTS results indicated that SCR reaction could occur following the Eley-Rideal (E-R) mechanism and Langmuir-Hinshelwood (L-H) mechanism simultaneously over 20Nb/CeSi2 catalyst, which could be attributed to the interaction between niobium and ceria in favor of the activation of inert surface nitrate, considered the primary factor for the improvement of the catalyst performance at low-temperature

Two-dimensional fiber-optic vector vibroscope using only one multi-mode tilted fiber grating

Orientation-recognized two-dimensional vibration sensor based on a polarization-controlled cladding-to-core recoupling is demonstrated experimentally. A compact structure in which a short section of multi-mode fiber stub containi

Strategic differentiation of subcommunities composed of evergreen and deciduous woody species associated with leaf functional traits in the subtropical mixed forest

The joint assembly of evergreen and deciduous tree species, typical karst vegetation of evergreen and deciduous broad-leaved mixed forests through respective subcommunities, play an important role in maintaining biodiversity in subtropical karst regions, and leaf functional traits can strategically specify plant resource utilization. However, it is unclear how these assembled subcommunities of evergreen and deciduous species maintain differentiation strategies. This study surveyed 53 forest plots of 20 m × 20 m dividing 212 adjacent lattices in a typical karst forest. Leaf traits of woody plants were measured regarding the specific leaf area (SLA), leaf dry matter content (LDMC), leaf tissue density (ltd), and leaf C, N, and P contents. The differences between deciduous and evergreen subcommunities were compared using the community-weighted means (CWM). The SLA and LDMC of the deciduous subcommunity were greater than the evergreen subcommunity; meanwhile, the leaf C, C/N and C/P ratios of the evergreen subcommunity were significantly higher than those of the deciduous subcommunity. However, the leaf N, P and N/P ratios of the deciduous subcommunity were significantly enhanced than the evergreen subcommunity. Moreover, both subcommunities showed significant negative correlations between SLA, leaf N and ltd, LDMC, signifying a trade-off of leaf-economic trait in deciduous and evergreen subcommunities. Furthermore, principal component analysis (PCA) on leaf functional traits specified the strategic differentiation mainly located at the side of the resource acquisition with high SLA and leaf N content for the deciduous subcommunity and situated at the side of the resource conservation with high LDMC and ltd for the evergreen subcommunity. In conclusion, the trade-off correlated with leaf functional trait differentiation suggested a resource acquisition strategy for the deciduous subcommunity and a resource conservation strategy for the evergreen subcommunity in the subtropical climate-dominating mixed forest of karst ecosystem

Image_3_Single-cell profiling of T cells uncovers a tissue-resident memory-like T-cell subset associated with bidirectional prognosis for B-cell acute lymphoblastic leukemia.tif

IntroductionThe character and composition of leukemia-related T cells are closely related to the treatment response and prognosis for patients. Though B cell-acute lymphoblastic leukemia (B-ALL) patients have benefited from immune-based approaches, such as chimeric antigen receptor T cells therapy, some of them still end with poor prognosis, especially for adult patients. Therefore, deep understanding of the developmental relationship between T cell subtypes in relation to B-ALL patient prognosis is urgently needed.MethodsWe analyzed the peripheral blood T cell single-cell RNA sequencing data of three B-ALL patients, using data from 11 healthy individuals as controls. In total, 16,143 and 53,701 T cells from B-ALL patients and healthy adults, respectively, were objectively analyzed for detailed delineation of 13 distinct T cell clusters. Cluster-specific genes were used as marker genes to annotate each T cell subtype.ResultsUnbiased analysis enabled the discovery of circulating CD103+ T cell (CD3+CD103+MKI67+), also defined as tissue-resident memory-like T (Trm-like) cell, populations were elevated in B-ALL patients, which expressed high level of cell proliferation and exhaustion related genes. In addition, cell fate trajectory analysis showed these Trm-like cells, which shared T-cell receptor (TCR) clonotypes with exhausted T (Tex) cells and effector T (Teff) cells, were supposed to transition into Teff cells; however, mainly transformed into Tex cells in leukemia environment. More importantly, Trm-like cells transformation into Teff cells and Tex cells potentially led to favorable or poor prognosis for B-ALL patients, respectively.ConclusionIn sum, a circulating Trm-like cell subset with high level expression of cell proliferation and exhaustion related genes was elevated in B-ALL patients. The bidirectional developmental potential of these T cells into Teff or Tex is closely associated with favorable or poor prognosis, respectively. Together, our study provided a unique insight of alteration of leukemia related T cells, also showed a potential immunotherapy direction and prognosis assessment model for B-ALL patients.</p