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In this paper,based on μ-CMOS sensor technology,the ultra-high-speed camera is used. Through design triggering energy of the drug packet and the synchronous controller are designed,The simultaneous loading of multiple shots in ultra-high speed DIC experimental system is developed.A model experiment is carried out and the distribution characteristics of the strain field in the metro tunnel near the side burst are obtained.The experimental results show that the propagation characteristics of the strain wave in the adjacent tunnel are related to the boundary conditions of the blasting tunnel.The effect of the blasting blasting at different positions on the characteristic points around the tunnel is different.The difference between higher and lower peak compressive strain is more than 4.5 times. The blasting stress concentrated area of the side close to tunnel is followed by the blast side of the straight wall,arched waist interchange,tunnel vault and floor center.

In a high-power semiconductor power module where multiple chips are populated in parallel, the thermal imbalance problem arises. In this article, the next-generation standard high-voltage insulated-gate bipolar transistor module for high-speed railcar traction is investigated to characterize the internal thermal imbalance among paralleling chips and evaluate the impact on temperature distribution in field application. The former is accomplished by a new test algorithm with a purposely designed module sample, while the latter is achieved via an advanced electro-thermal simulation from chip level to system level. The experimentally verified thermal network among paralleling chips reveals the multiple reasons for the thermal imbalance. A comparison between the simulation and experimental results regarding the paralleling chips’ power-cycling scenario helps to confirm the effectiveness of the chip model, the thermal network, and the electro-thermal simulation approach. A further electro-thermal simulation shows that the module internal thermal imbalance can lead to significant junction temperature discrepancy among paralleling chips in traction inverter applications, which should be taken into consideration for the long-term reliability assessment. [ABSTRACT FROM AUTHOR]

A method to derive the junction-to-case level coupling thermal resistances among paralleling chips in the multichip semiconductor power module has been proposed in this article. It is revealed that the traditional structure function methodology (SFM), which is developed for analyzing the self-heating effect of the driving-point chip, cannot be applied directly in the thermal coupling analysis, where the influence of the driving-point chip on the neighboring acceptor chip is concerned. This article shows that by combining the traditional SFM with the frequency-domain analysis (FDA), the effective separation points between the module case and the external cooling setup can be identified in both time and frequency domains, which correspond to the characteristic frequency points in the complex loci of the thermal impedance curves. By extracting the amplitudes at the characteristic frequencies from the complex loci in the FDA, the junction-to-case level coupling thermal resistances can be derived. Both simulation and experimental study have been carried out to verify the concept. The agreement between the two justifies the proposed method. [ABSTRACT FROM AUTHOR]

With the rapid development of wide‐band gap semiconductor chip and package technologies, the voltage class of commercial silicon carbide (SiC) device is gradually improved. This paper concentrates on the latest 3.3‐kV full SiC‐based metal oxide semiconductor field‐effect transistor (MOSFET) device and its application in railway traction. First, compared with the Si‐based insulated‐gate bipolar transistor (IGBT), the SiC‐based MOSFET shows lower switching loss but weaker short‐circuit capacity. Second, in the railway traction application, the SiC‐based MOSFET with high switching frequency could reduce the inverter loss, the harmonic loss and the noise of traction motor. Third, a well‐designed filter is necessary between the inverter and the motor to prevent the motor from terminal overvoltage and insulation problem, which are resulted from long cable and high dv/dt. Finally, a full‐SiC railway traction inverter prototype is built and tested, and shows obvious advantages on miniaturization and lightweight. [ABSTRACT FROM AUTHOR]

SiC MOSFETs have received great attention due to their excellent electrothermal properties. Accurate junction temperature information of SiC MOSFETs ensures safe operation and helps effective thermal management. However, the existing thermal models have limits to correctly predict the thermal behaviors, whose parameter extraction processes are normally complicated. Most of the thermal models generally omit the temperature effects, which greatly impairs their usefulness and effectiveness. Here, a temperature-dependent physical resistor–capacitor (RC) network model is proposed, which can accurately characterize the thermal behavior of SiC MOSFETs particularly under high-temperature conditions. Meanwhile, the boundary conditions are fully investigated and modeled, which guarantees the adaptation of the proposed model for different real-field applications. The proposed method can remarkably simplify the process of parameter extraction since only the steady-state temperature distribution information is required with the assistance of finite-element method (FEM). Finally, the effectiveness and the robustness of the proposed model are validated by FEM simulation and experiments. [ABSTRACT FROM AUTHOR]

A type of 3.3-kV/450-A half-bridge insulated-gate bipolar transistor power module combining the silicon (Si) and silicon carbide (SiC) technologies has been developed and reported in this article, for the miniaturization of the Chinese high-speed railway rolling stock traction inverters. This module is developed by integrating the next-generation industrial standard high-voltage packaging topology and the state-of-the-art 3.3 kV wide bandgap semiconductor chip technology, to reduce the waste power dissipation during operation, which in turn can lead to effective downsizing of key components in the traction inverter design. The module layout characteristics and the SiC Schottky barrier diodes design for substitution of the conventional Si fast recovery diodes will be described in detail. The mechanical, thermal, and electrical performances of the hybrid module are compared comprehensively with the Si-based counterpart. Based on the experimental results, an inverter system level evaluation of both modules is also conducted by electro-thermal simulation. The hybrid module shows advantages in loss reduction leading to great potential of system miniaturization, which is a cost effective solution for massive upgrading of the existing high-speed train traction inverters. [ABSTRACT FROM AUTHOR]

As a classical insulated gate bipolar transistor (IGBT) structure, the trench-gate field-stop (FS) IGBT has been widely used. For more convenient application, physics-based trench-gate FS IGBT models have received great attentions due to its effectiveness in simulating key device properties. However, current IGBT modeling studies for this popular IGBT chip seldom investigate the depletion layer behavior under the trench-gate structure. This article first derives the physics-based miller capacitance formula for the trench-gate structure according to finite element method (FEM) simulation. Another haunting issue for these physics-based IGBT models is that the intrinsic device parameters are difficult to be extracted appropriately. Thus, an FEM FS IGBT model is established in Sentaurus TCAD as the benchmark. Then, an improved parameter extraction procedure for a Fourier-series-based (FSB) IGBT model is proposed based on the improved miller capacitance formula. By the particle swarm optimization algorithm, key device parameters for the FSB IGBT model can be successfully extracted by fitting the simulated waveforms to those by FEM simulation at a randomly selected turn-off operating condition. Parameters extracted through the proposed procedure using the FSB IGBT model with the improved miller capacitance formula are very close to the device parameters of the FEM model. More importantly, the reliability and the robustness of the extracted parameters are further validated by comparing the waveforms of FSB model with those of FEM model at different operating conditions. [ABSTRACT FROM AUTHOR]

The Fourier-series-based insulated-gate bipolar transistor (IGBT) model has been very effective in simulating its switching behaviors and meanwhile, reflecting carrier dynamics. However, in turn-on process, such a model has difficulty in distinguishing the boundary between undepleted area and depletion layer of the drift region due to Gibbs phenomenon and therefore, cannot accurately describe the carrier behavior of carrier storage region (CSR). In this study, the Fourier-series-based model is modified to determine the more precise depletion layer edge for turn on. This is achieved by utilizing the actual characteristics of the carrier concentration gradient at the edge of CSR in turn-on process. Such a modified model is implemented in MATLAB/Simulink and it can better reflect the depletion layer and simulate the distribution of both the carrier concentration and electric field during turn-on process. It corrects the unreasonable voltage tail caused by the error of drift region voltage calculation in previous models. The results of the proposed model under both the resistive load and inductive load are in good agreement with TCAD. Such a modified model can more accurately simulate both carrier dynamics and switching behaviors in the turn-on process. [ABSTRACT FROM AUTHOR]

Solder interconnects are essential to the reliability of electronic devices. The addition of alloying elements was reported to provide beneficial effects to the microstructure and mechanical reliability of lead-free solder alloys. In this work, the effects of Sb addition on the mechanical behavior of SAC305 solder alloy were investigated. Based on differential thermal analysis, it was observed that melting point of SAC-Sb solder was slightly higher than that of SAC305. The mechanical behavior was studied at different temperatures (25 °C–125 °C) and strain rates (1 × 10−4 – 1 × 10−2 1/s) for SAC-Sb and SAC 305 solders as a comparison. From the results, ultimate tensile strength of SAC-Sb (10–72 MPa) was generally higher than that of SAC305 (4.54–61.5 MPa) at the aforementioned test conditions. A linear relation between the UTS and yield strength and temperature was identified for test results of SAC305, but the relation was found to be nonlinear for SAC-Sb solder because of solution strengthening effect of Sb in the Sn matrix. Parameters of Anand model were estimated based on mechanical behavior of SAC-Sb and SAC305 solders. Next, the model was used to evaluate thermal fatigue life of an insulated gate bipolar transistor (IGBT) module with SAC-Sb and SAC305 as chip-to-directed bonding copper (DBC) and DBC-to-baseplate attachment materials by finite element modeling. The increase of maximum inelastic strain in one thermal cycle in SAC-Sb solder joints was lower than that in SAC305 solder joints. This result indicates that SAC-Sb solder can provide a considerably better fatigue life under harsh service conditions. [ABSTRACT FROM AUTHOR]

A state-of-the-art 3.3-kV/450-A hybrid power module for the next generation traction inverter of rolling stock is reported in this paper, combining the silicon (Si) insulated-gate bipolar transistor (IGBT) and silicon carbide Schottky barrier diodes (SBDs) chips. Compared with the existing hybrid technology at the same voltage level, this module is characterized by a half-bridge topology, in which 6 IGBT and 12 SBD chips are integrated in each switch. The outnumbering of the diodes represents a promising mitigation to the low availability of SBDs at this voltage level. Both static and dynamic test of this module and an equivalent Si-based module are carried out comparatively. Apart from describing the features of compactness, low-inductance, and good current distribution among chips, this module is characterized by low turn-on current overshooting and turn-on loss of IGBTs, negligible diode reverse recovery time and loss, as well as flexible allowance of IGBT turn-on current rising rate $\boldsymbol{dI}/\boldsymbol{dt}$. A parameterized study is carried out to benchmark the advantage of this new topology. Based on the experimental results, the performance of the hybrid module in a three-phase traction inverter circuit is also evaluated by means of electro-thermal simulation. The hybrid module distinguishes itself by describing much lower power loss and junction temperature than its Si-based counterpart. [ABSTRACT FROM AUTHOR]

We present in this paper an advanced electromagnetic (EM)-electrothermal analysis approach for the semiconductor power devices, with illustration on the insulated-gate bipolar transistor (IGBT) modules. This method distinguishes itself by dynamically integrating the EM domain into the circuit-type electrothermal coupling analysis, thus enabling the multi-dimensional simulation that spans in time from nanoseconds to seconds, and in space from chip level to system level. In particular, it contains a parametric-extracted electrothermal model of the IGBT chip and a comprehensive 0-D thermal network as well as an EM network extracted from the 3-D module packaging structure for each paralleling chip. The incorporation of the EM, as well as thermal networks representing the 3-D packaging structure, reveals essential information about the current imbalance, power dissipation imbalance, and thermal imbalance inside the IGBT module with paralleling chips, which have a strong influence on the module reliability. To demonstrate the application of this approach, an unfavorably designed 1700-V/450-A half-bridge IGBT power module is evaluated in the simulation circuit, with experimentally verified electrothermal IGBT chip model and thermal as well as EM networks. The results have shown that the EM-electrothermal analysis can successfully reveal the dynamic interaction among different physical domains and, thus, the current as well as temperature imbalance among the paralleling chips inside the power module. The predicted current imbalance also agrees with that from the experimental test. [ABSTRACT FROM AUTHOR]

The eukaryotic genome is organized at varying levels into chromosome territories, transcriptional compartments and topologically associating domains (TADs), which are architectural features largely shared between different cell types and across species. In contrast, within TADs, chromatin loops connect enhancers and their target genes to establish unique transcriptomes that distinguish cells and tissues from each other and underlie development and differentiation. How these tissue-specific and temporal stage-specific long-range contacts are formed and maintained is a fundamental question in biology. The widely expressed L im d omain b inding 1 protein, LDB1, plays a critical role in connecting enhancers and genes by forming complexes with cell-type specificity across diverse developmental pathways including neurogenesis, cardiogenesis, retinogenesis and hematopoiesis. Here we review the multiple roles of LDB1 in cell fate determination and in chromatin loop formation, with an emphasis on mammalian systems, to illuminate how LDB1 functions in normal cells and in diseases such as cancer. • During development, transcriptional enhancers interact over long genomic distances with target genes • Enhancer-gene interactions are highly cell type specific and influence cell fate decisions • The diverse class of nuclear LIM-homeodomain and LIM-only proteins play a central role in development and differentiation • LDB1 binds to LIM proteins at enhancers mediating contact with target genes in diverse cell types from C. elegans to man [ABSTRACT FROM AUTHOR]

Enhancers establish proximity with distant target genes to regulate temporospatial gene expression and specify cell identity. Lim domain binding protein 1 (LDB1) is a conserved and widely expressed protein that functions as an enhancer looping factor. Previous studies in erythroid cells and neuronal cells showed that LDB1 forms protein complexes with different transcription factors to regulate cell-specific gene expression. Here, we show that LDB1 regulates expression of liver genes by occupying enhancer elements and cooperating with hepatic transcription factors HNF4A, FOXA1, TCF7 and GATA4. Using the glucose transporter SLC2A2 gene, encoding GLUT2, as an example, we find that LDB1 regulates gene expression by mediating enhancer-promoter interactions. In vivo, we find that LDB1 deficiency in primary mouse hepatocytes dysregulates metabolic gene expression and changes the enhancer landscape. Conditional deletion of LDB1 in adult mouse liver induces glucose intolerance. However, Ldb1 knockout hepatocytes show improved liver pathology under high-fat diet conditions associated with increased expression of genes related to liver fatty acid metabolic processes. Thus, LDB1 is linked to liver metabolic functions under normal and obesogenic conditions., (Published by Oxford University Press on behalf of Nucleic Acids Research 2022.)

The eukaryotic genome is organized at varying levels into chromosome territories, transcriptional compartments and topologically associating domains (TADs), which are architectural features largely shared between different cell types and across species. In contrast, within TADs, chromatin loops connect enhancers and their target genes to establish unique transcriptomes that distinguish cells and tissues from each other and underlie development and differentiation. How these tissue-specific and temporal stage-specific long-range contacts are formed and maintained is a fundamental question in biology. The widely expressed Lim domain binding 1 protein, LDB1, plays a critical role in connecting enhancers and genes by forming complexes with cell-type specificity across diverse developmental pathways including neurogenesis, cardiogenesis, retinogenesis and hematopoiesis. Here we review the multiple roles of LDB1 in cell fate determination and in chromatin loop formation, with an emphasis on mammalian systems, to illuminate how LDB1 functions in normal cells and in diseases such as cancer., (Published by Elsevier B.V.)

HOX cluster genes are activated sequentially in their positional order along the chromosome during vertebrate development. This phenomenon, known as temporal colinearity, depends on transcriptional silencing of 5' HOX genes. Chromatin looping was recently identified as a conserved feature of silent HOX clusters, with CCCTC-binding factor (CTCF) binding sites located at the loop bases. However, the potential contribution of CTCF to HOX cluster silencing and the underlying mechanism have not been established. Here, we demonstrate that the HOXA locus is organized by CTCF into chromatin loops and that CTCF depletion causes significantly enhanced activation of HOXA3 to -A7, -A9 to -A11, and -A13 in response to retinoic acid, with the highest effect observed for HOXA9. Our subsequent analyses revealed that CTCF facilitates the stabilization of Polycomb repressive complex 2 (PRC2) and trimethylated lysine 27 of histone H3 (H3K27me3) at the human HOXA locus. Our results reveal that CTCF functions as a controller of HOXA cluster silencing and mediates PRC2-repressive higher-order chromatin structure., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)