Search

C and Mo in the form of solid solution atom or compound phase is distributed in CoCrFeMnNi high entropy alloy (HEA), which have the effects of solution strengthening or second phase strengthening. CoCrFeMnNi–Mo5C0.5 HEA were prepared by adding C and Mo elements to CoCrFeMnNi HEA, and then which heat treatment were carried out by furnace-cooling, air-cooling and water-cooling respectively. the microstructure and phase composition of as-cast or heat treated CoCrFeMnNi–Mo5C0.5 HEA were examined by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD), the mechanical properties of as-cast or heat treated CoCrFeMnNi–Mo5C0.5 HEA were tested by the tensile test and hardness test, and the effects of heat treatment cooling methods on precipitated second phase and mechanical properties of CoCrFeMnNi–Mo5C0.5 HEA were investigated. The results show that precipitated second phase in CoCrFeMnNi–Mo5C0.5 HEA is MC phase, which is rich in Mo, Cr and C elements. With change of heat treatment cooling methods from furnace-cooling, air-cooling to water-cooling respectively, heat treatment cooling rate is increased. With increase of heat treatment cooling rate, the amount and size of precipitated second phase are all decreases, and the position of second phase precipitation changes from grain boundaries to intragranular. The tensile strength and elongation of heat treatment water-cooled CoCrFeMnNi–Mo5C0.5 HEA are 739 MPa and 41% respectively, which are realizes the simultaneous increased of strength and plasticity. With increase of heat treatment cooling rate, the hardness of CoCrFeMnNi–Mo5C0.5 HEA decreases, the uniform plastic deformation and the elongation are all increases, and the plasticity increase. The fractures of as-cast, heat treatment furnace-cooled, air-cooled and water-cooled CoCrFeMnNi–Mo5C0.5 HEA are all brittle fracture with cleavage characteristics, and the plastic deformation occurs mainly in the uniform plastic deformation stage. The fracture mode of as-cast CoCrFeMnNi–Mo5C0.5 HEA is intergranular fracture, the fracture mode of heat treatment furnace-cooled, air-cooled and water-cooled CoCrFeMnNi–Mo5C0.5 HEA are all transgranular fracture.

3D concrete printing technology has enabled the construction of full-scale bridges. However, structural carbon emissions due to higher cement content and limitations of embedded reinforcement have limited its widespread adoption. This paper presents a non-reinforced 3D printed concrete box arch bridge and describes its design, construction, dismantlement, and reconstruction, as well as evaluation of the carrying capacity of reconstructed primary arch ring. The bridge adheres to current technical principles and bridge engineering specifications. By taking into account the mechanical anisotropy and primary stress characteristics of the arch, the design negates the need for reinforcement. The study showcases the reusability and potential carbon emission reduction through block printing, on-site assembly, block removal, and secondary usage. The safety of the reconstructed arch bridge was confirmed through an in-situ load test.

Ultra-High performance concrete (UHPC) has garnered considerable attention in the construction industry due to its exceptional mechanical properties and durability. In the design of UHPC beams, accurately predicting shear strength is crucial. Inspired by the dense blocks in DenseNet, this paper proposes a novel neural network for predicting the shear strength of UHPC beams. A comprehensive database of UHPC beams was initially established through extensive literature data collection, amassing 619 experimental data samples. Preprocessing was subsequently conducted using mahalanobis distance (DM) to eliminate outliers. Subsequently, the database underwent detailed parameter analysis. In practical testing, the novel neural network model exhibited superior accuracy in predicting the shear strength of UHPC beams, surpassing traditional machine learning (ML) models and empirical formulas. Furthermore, it demonstrated excellent generalization capabilities, achieving an R2 value of 0.988 in the training set and 0.964 in the test set. The study introduced the shapley additive explanations (SHAP) method to conduct global and local interpretability analysis of the network model, demonstrating the contributions of each input parameter to the model predictions. Finally, based on this network model, a graphical user interface (GUI) was developed for researchers engaged in UHPC beam design, enabling users to easily input relevant parameters and obtain shear strength predictions. The findings of this study are expected to promote the application of ML models in predicting the complex nonlinear behavior of UHPC structures, providing strong support for engineering practice.

The as-cast (Fe50Mn30Co10Cr10)97C2Mo1 HEA (high entropy alloy) was cold rolled to 90 % (CR90 %), followed by annealing at different temperatures (400 °C, 500 °C, 600 °C). Their microstructure and mechanical properties have been systematically investigated. The results show that this HEA has a single FCC structure, and that annealing at 500 °C and 600 °C leads to the formation of Cr-rich σ phase. The CR90 % HEA exhibits the tensile strength of 1926 MPa and 4 % elongation. However, annealing at 400 °C and 500 °C makes the tensile strength improve to ∼2078 MPa and ∼2060 MPa, respectively, while their plasticity does not change significantly. Annealing at 600 °C results in a significant reduction in the strength (∼1650 MPa) while a slight increase in plasticity. The element segregation and the formation of nano-sized (Fe, Mn)-rich precipitates are contributed to the significant increase in tensile strength of the HEA annealed at 400 °C. Nevertheless, annealing at 600 °C leads to a decrease in the density of defects (e.g. dislocations) caused by cold rolling and the increase in the grain size, which finally resulting in a reduction in strength.

The interlocking can effectively improve the mechanical properties of concrete. However, the strength of 3D printed concrete with interlocking interfaces, fabricated using non-automated methods, is reduced due to the time-consuming interface processing. Additionally, studies on the effects of interlocking on the mechanical properties, failure modes, and anisotropic behavior of 3D printed concrete are not yet systematic. In order to address these issues, a printing forming scheme and nozzles were designed for interlayer interlocking 3D printing, and the mechanical properties of interlayer interlocking 3D printed concrete were tested. Firstly, the forming scheme and nozzles are specifically designed for the preparation of 3D printed concrete with interlocking interfaces between the layers. Furthermore, extrudability tests are carried out to determine the appropriate printing parameters for interlayer interlocking 3D printed concrete. Finally, specimens were printed, and interfacial splitting tests, interlayer interfacial shear tests, and compression tests were conducted. The results reveal that: (1) by utilizing the appropriate extrusion rate of the rotating shaft and nozzle travel speed, better-formed interlayer interlocking concrete filaments can be obtained. (2) the interlayer interlocking 3D printed specimens exhibit higher strength. The interfacial splitting tensile strength is increased by about 14.5–30.7 %, and the interlayer interfacial shear strength is increased by about 7.8–18.0 % compared to those with smooth interlayer interfaces. (3) the interlayer interlocking 3D printed concrete exhibits a reduction in the anisotropic coefficient of about 13.7–25.5 %, and the anisotropy is significantly weakened.

High-voltage switchgear is a key control and protection unit in power systems. The reliable operation of the operating mechanism is essential for the reliable opening and closing of the switchgear. This is a vital guarantee for the safety and stability of the power systems. The spring operating mechanism is a commonly used actuator for circuit breakers at 12–252 kV. However, a reliability estimation method that is convenient, practical and accurate is still lacking. The aim of this paper is to explore a reliability estimation method based on a stress–strength interference reliability theory and a fatigue life theory. The changing rules of the reliability of the main axis, and the closing pawl and opening pawl in the spring operating mechanism during operations, are achieved. The accuracy of the calculated reliability based on theories of stress–strength interference and fatigue life is verified by adopting a test data statistical reliability model based on Weibull distribution. The results show that the reliability estimation method based on stress–strength interference and fatigue life theories has a high degree of confidence. The maximum tolerance is 0.024. The study would help in providing a useful reference for the optimization and durability estimation of a spring operating mechanism and its key components in high-voltage circuit breakers.

Abstract FMR1, a new m6A reader, is known to be involved in the regulation of cancer progression. However, its role, regulatory mechanism, and clinical significance in colorectal cancer (CRC) are elusive. Here, we showed that FMR1 was upregulated in CRC, and it promoted proliferation and metastasis of CRC cells in vitro and in vivo. Mechanically, FMR1 recognized the m6A-modification site in EGFR mRNA, a key molecule in cancer occurrence and targeted therapy, sustained its stability and maintained its expression in an m6A-dependent manner, thereby promoting the tumorigenesis and metastasis of CRC. And the effect of FMR1 knockdown in CRC cells could be abolished by METTL3. Furthermore, FMR1 shRNA plasmid carried by attenuated Salmonella has an effective anti-tumor effect in vivo. Collectively, we identified the METTL3/FMR1/EGFR axis in the progression of CRC. This novel mechanism indicated that the METTL3/FMR1/EGFR axis is a potential target for early therapeutic intervention in CRC progression.

Even though switching in vacuum is a technology with almost 100 years of history, its recent developments are still changing the future of power transmission and distribution systems. First, current switching in vacuum is an eco-friendly technology compared to switching in SF6 gas, which is the strongest greenhouse gas according to the Kyoto Protocol. Vacuum, an eco-friendly natural medium, is promising for reducing the usage of SF6 gas in current switching in transmission voltage. Second, switching in vacuum achieves faster current interruption than existing alternating current (AC) switching technologies. A vacuum circuit breaker (VCB) that uses an electromagnetic repulsion actuator is able to achieve a theoretical limit of AC interruption, which can interrupt a short-circuit current in the first half-cycle of a fault current, compared to the more common three cycles for existing current switching technologies. This can thus greatly enhance the transient stability of power networks in the presence of short-circuit faults, especially for ultra- and extra-high-voltage power transmission lines. Third, based on fast vacuum switching technology, various brilliant applications emerge, which are benefiting the power systems. They include the applications in the fields of direct current (DC) circuit breakers (CBs), fault current limiting, power quality improvement, generator CBs, and so forth. Fast vacuum switching technology is promising for controlled switching technology in power systems because it has low variation in terms of opening and closing times. With this controlled switching, vacuum switching technology may change the “gene” of power systems, by which power switching transients will become smoother.

Abstract Fast clearing of a short‐circuit fault is vital to increase the transmission capacity of power grid transmission lines and improve the transient stability of a power system. A fast vacuum circuit breaker (FVCB) is a good candidate to realize quick elimination of a short‐circuit fault. The original contribution of this paper is to present the design of a 72.5 kV single‐break FVCB and its verification of short‐circuit breaking performance. A specially designed 72.5 kV vacuum interrupter, with floating shields and reduced mass of moving components, was developed. An electromagnetic repulsion actuator was used to provide a high initial opening speed, V1, of 5 m/s over half of the full‐contact gap and a relatively low average opening speed, V2, of 1.59 m/s in the full contact gap of 30 mm. The high‐designed V1 and low‐designed V2 were achieved with the aid of a deliberately designed oil buffer. The opening and closing time of the designed 72.5 kV FVCB was 1.2 ± 0.04 ms and 18 ± 0.20 ms respectively. The terminal fault test duty of T100s(b), carried out on the 72.5 kV FVCB, demonstrated both the 40 kArms and 80 kArms short‐circuit current breaking performance. The short‐circuit current breaking arcing time windows of FVCB, including the minimum arcing time, the maximum arcing time, and the middle arcing time, was verified to fulfill the requirement of the international standard, IEC 62271‐100 2017, and the Chinese standard, GB/T 1984–2014, both for the 40 kArms and 80 kArms switching cases, respectively. Further development of the 72.5 kV single‐break FVCB would benefit the development of ultra‐ or extra‐high voltage FVCBs by reducing essential numbers of series‐connected breaking units.

Abstract Previous studies mainly focused on the behaviours of single‐break vacuum circuit breakers (VCBs) in switching capacitor banks. The prestrike characteristics of double‐break VCBs subjected to axial magnetic fields (AMFs) and transverse magnetic fields (TMFs) in capacitive making operations, to find a proper structure of double‐break VCBs for capacitive switching are experimentally investigated here. Special attention is given to the prestrike gap, inrush current interruption, prestrike voltage, prestrike electric field strength and erosion on contact surfaces of double‐break VCBs. The results show that the 50% prestrike gap d50 and the scatter in prestrike gaps are significantly reduced by nearly 50% by the TMF double‐break VCB compared with the AMF double‐break VCB. The 50% prestrike arcing time ta50 of the TMF double‐break VCB can be reduced by 37.0% compared with the AMF double‐break VCB. The voltage distribution ratio between two vacuum interrupters (VIs) is more balanced in the TMF double‐break VCB (6:4) than in the AMF double‐break VCB (7:3) when prestrike occurs. The TMF double‐break VCB can reduce the erosion caused by inrush currents on contact surfaces compared with the AMF double‐break VCB. In switching capacitor banks, the TMF double‐break VCB is superior to the AMF double‐break VCB.

BackgroundAlthough emerging evidence supports the relationship between necroptosis (NEC) related genes and hepatocellular carcinoma (HCC), the contribution of these necroptosis-related genes to the development, prognosis, and immunotherapy of HCC is unclear.MethodsThe expression of genes and relevant clinical information were downloaded from TCGA-LIHC, LIRI-JP, GSE14520/NCI, GSE36376, GSE76427, GSE20140, GSE27150, and IMvigor210 datasets. Next, we used an unsupervised clustering method to assign the samples into phenotype clusters base on 15 necroptosis-related genes. Subsequently, we constructed a NEC score based on NEC phenotype-related prognostic genes to quantify the necroptosis related subtypes of individual patients.ResultsWe divided the samples into the high and low NEC score groups, and the high NEC score showed a poor prognosis. Simultaneously, NEC score is an effective and stable model and had a good performance in predicting the prognosis of HCC patients. A high NEC score was characterized by activation of the stroma and increased levels of immune infiltration. A high NEC score was also related to low expression of immune checkpoint molecules (PD-1/PD-L1). Importantly, the established NEC score would contribute to predicting the response to anti-PD-1/L1 immunotherapy.ConclusionsOur study provide a comprehensive analysis of necroptosis-related genes in HCC. Stratification based on the NEC score may enable HCC patients to benefit more from immunotherapy and help identify new cancer treatment strategies.

Abstract Background As thyroid fine needle aspiration (FNA) shows a certain limitation in the diagnosis of conventional smears, novel approaches like liquid-based cytology (LBC) have been gradually applied recently. Studies have shown the difference between the conventional smears (CSs) and liquid-based smears on fine needle aspiration cytology (FNAC) diagnosis, but the impacts of different liquid-based preparation (LBP) methods, including membrane-based and sedimentation, on diagnosis are still not clear. In this study, the effects of liquid-based smears prepared by different methods on the cytological interpretation were studied. Methods A total of 221 thyroid liquid-based FNAC cases from January 2017 to October 2018 were collected. We retrospectively studied and compared the effects of the membrane-based and sedimentation LBP methods through The Bethesda System for Reporting Thyroid Cytopathology (TBS) diagnosis and risk of malignancy assessment. Besides, we made an evaluation on the diagnostic differences in the effects of different preparation methods on the cell morphology and tissue structure of papillary thyroid carcinoma (PTC) for more accurate FNAC diagnosis. Results Among the 221 cases reviewed, membrane-based method was applied in 153 cases and sedimentation in 68 cases. According to the diagnostic criteria of 2017 TBS, TBSVI and TBSV thyroid could be cytologically diagnosed by membrane-based (49.0% (75/153) and 25.5% (39/153)) and sedimentation (52.9(36/68) and 25(17/68)) methods, and both were confirmed as PTC through histopathological diagnosis after operation, with the malignancy degree as high as 100%. In addition, of the 30 cases that were diagnosed as TBSIII thyroid nodules with the membrane-based method, 15 cases were pathologically malignant after an operation, with the malignancy degree of 50% (15/30), while that in 11 cases using the sedimentation method was 45.4% (5/11). PTC could be detected in both the TBSIV and TBSII thyroid nodules diagnosed by membrane-based method, with the sensitivity of 87.0% (114/131) lower than that by sedimentation method (91.4% (53/58)), showing the lower consistency with the histopathological result (K = 0.635 vs K = 0.757). Among the membrane-based smears, 23.5% (36/153) had fewer follicular epithelial cells, 55.6% (20/36) of which were considered to be suspicious for PTC from cell karyotype and tissue arrangement. While among the sedimentation smears, 16.2% (11/68) had fewer follicular epithelial cells, and 63.6% (7/11) was suspicious for PTC. In 72.5% (95/131) membrane-based smears of PTC, the papillary and swirling structures were not obvious, showing as crowded syncytial cell masses, while in 55.2% (32/58) sedimentation smears, both structures were visible with obvious three-dimensional papillary structure, and the fibrovascular axis still remained. Conclusion LBP technique is feasible for FNAC diagnosis, and the sedimentation shows more advantages, like higher PTC detection rate and good consistency with postoperative histopathological diagnosis. A clear understanding of the subtle differences in the effects of membrane-based and sedimentation methods on the cell morphology and tissue structure could be conducive to the definitive diagnosis of PTC before operation.

Liquefaction evaluation on the sands induced by earthquake is of significance for engineers in seismic design. In this study, the random forest (RF) method is introduced and adopted to evaluate the seismic liquefaction potential of soils based on the shear wave velocity. The RF model was developed using the Andrus database as a training dataset comprising 225 sets of liquefaction performance and shear wave velocity measurements. Five training parameters are selected for RF model including seismic magnitude (Mw), peak horizontal ground surface acceleration (amax), stress-corrected shear wave velocity of soil (Vs1), sandy-layer buried depth (ds), and a new introduced parameter, stress ratio (k). In addition, the optimal hyperparameters for the random forest model are determined based on the minimum error rate for the out-of-bag dataset (ERROOB) such as the number of classification trees, maximum depth of trees, and maximum number of features. The established random forest model was validated using the Kayen database as testing dataset and compared with the Chinese code and the Andrus methods. The results indicated that the random forest method established based on the training dataset was credible. The random forest method gave a success rate for liquefied sites and even a total success rate for all cases higher than 80%, which is completely acceptable. By contrast, the Chinese code method and the Andrus methods gave a high success rate for liquefaction but very low for nonliquefaction which led to the increase of engineering cost. The developed RF model can provide references for engineers to evaluate liquefaction potential.

The current liquefaction evaluation methods mainly focus on the success rate for liquefied sites so that the evaluation result tends to be conservative at different seismic intensities. Therefore, a new formula about liquefaction evaluation by introducing logistic regression theory is proposed to solve the deficiencies of the current evaluation method, which is based on 225 sets of shear wave velocity data reported by Andrus. The reliability of the new formula is verified based on 336 sets of Vs data collected from the Kayen database. The performance of the new formula on liquefaction evaluation is compared with existing liquefaction evaluation methods including the Andrus method and the Chinese code method. Compared with the Andrus method and Chinese code method, the success rates of liquefaction evaluation given by the new formula under different seismic intensities are more balanced between liquefied site and nonliquefied site. The new formula at 50% probability of liquefaction is more adaptable for a wide range of seismic intensities, ground water table, and sand buried depth. In addition, the new formula at different probabilistic levels of liquefaction can be adopted based on the importance of the engineering site in risk analysis.

Three-dimensional concrete printing is a promising technology and attracts the significant attention of research and industry. However, printable and mechanical capacities are required for 3D printable cementitious materials. Moreover, the quantitative analysis methods of printable performance are limited and have low sensitivity. In this study, the orthogonal experiment through samples combining 3D concrete printing method with fly ash, silica fume, and ground granulated blast furnace slag was designed to obtain the printable and mechanical property influence of various mix proportions. Furthermore, multiple industrial wastes were utilized to improve material sustainability. Meanwhile, the static and dynamic extrusion pressure measured by the original 3D printing extrudability tester were verified to achieve a high-sensitivity evaluating indicator. Thereby, a novel high-sensitivity quantitative analysis method of printable capacity was established to explore the influence of industrial wastes usage on the printability of 3D printable mortars. The optimum dosage of fly ash, silica fume, and ground granulated blast furnace slag was 20 wt.%, 15 wt.%, and 10 wt.%, respectively, based on printable and mechanical property experiments. Furthermore, the optimum dosage was employed to print the sample and achieved a higher compressive strength (56.3 MPa) than the control cast.

This study examines the cyclic behavior of calcareous sand obtained from the South China Sea. A series of undrained cyclic triaxial tests were performed on the calcareous sand with various relative densities, cyclic stress ratios, and effective confining pressures. The test results show that whereas the effective confining pressure exhibited a small influence on the cyclic behavior of the calcareous sand, the effect of changes in CSR and relative density was notable. Due to its angular nature, the liquefaction resistance of calcareous sand was much higher than that of silica sand. In addition, differences between calcareous and silica sands in terms of pore pressure generation characteristics and deformation responses were also observed.

It is effective to open the bus-coupler circuit breaker in case of a short-circuit fault. A fast vacuum circuit breaker (FVCB) is an ideal bus-coupler circuit breaker due to its high velocity. The objective of this study was to develop and test a 252 kV/2500 A-40 kA multi-break bus-coupler FVCB. The 252 kV FVCB contained 12 FVCB units. Each phase consisted of four FVCB units connected in series. Each FVCB unit had an electromagnetic repulsion mechanism with an average opening velocity reaching 6.5 m/s. Test results showed the opening time was 1.11 ± 0.08 ms. The capacitance of the voltage grading capacitor of each break was determined to be 10 nF. The prototype 252 kV bus-coupler FVCB passed all partial test duties according to the IEC 62271-100: 2008 and IEC 62271-1: 2007 standards, which include an insulation test and a terminal fault test among others. A 252 kV/2500 A-40 kA multi-break bus-coupler FVCB can be used to quickly cut off a short-circuit fault and effectively limit a short-circuit current.

The prestrike phenomenon in vacuum circuit breakers (VCBs) is interesting but complicated. Previous studies mainly focus on the prestrike phenomenon in single-break VCBs. However, experimental work on prestrike characteristics of double-break VCBs cannot be found in literature. This paper aims to experimentally determine the probabilistic characteristics of prestrike gaps in a double-break VCB consisting of two commercial vacuum interrupters (VIs) in series under direct current (DC) voltages. As a benchmark, single-break prestrike gaps were measured by short-circuiting one of the VIs in a double break. The experimental results show that the 50% prestrike gap d50 of each VI in a double break, which is calculated with the complementary Weibull distribution, was significantly reduced by 25% to 72.7% compared with that in a single break. Due to the voltage-sharing effect in the double-break VCB, scatters in prestrike gaps of each VI in a double break was smaller than that in a single break. However, without the sharing-voltage effect, d50 of the low-voltage side in the double break was 65% higher than that of the same VI in the single break, which could be caused by the asynchronous property of mechanical actuators, the difference of the inherent prestrike characteristics of each VI and the unequal voltage-sharing ratio of VIs.