摘要：According to the requirements of a solar dish-Brayton system,a centrifugal compressor stage with a minimum total pressure ratio of 5,an adiabatic efficiency above 75% and a surge margin more than 12% needs to be designed.A single stage,which consists of impeller,radial vaned diffuser,90° crossover and two rows of axial stators,was chosen to satisfy this *** achieve the stage performance,an impeller with a 6:1 total pressure ratio and an adiabatic efficiency of 90% was designed and its preliminary geometry came from an in-house one-dimensional *** vaned diffuser was applied downstream of the *** rows of axial stators after 90° crossover were added to guide the flow into axial *** jet-wake flow,shockwave and boundary layer separation coexisted in the impeller-diffuser region,optimization on the radius ratio of radial diffuser vane inlet to impeller exit,diffuser vane inlet blade angle and number of diffuser vanes was carried out at design ***,an optimized centrifugal compressor stage fulfilled the high expectations and presented proper *** simulation showed that at design point the stage adiabatic efficiency was 79.93% and the total pressure ratio was *** surge margin was 15%.The performance map including 80%,90% and 100% design speed was also presented.

摘要：Mathematical model of solute [C] distribution in twin-roll strip casting process has been setup successfully with Calcosoft for the first time. Simulation result shows that in the center of the molten steel pool between the two rolls there is a vortex flow, which is a solute enriched area. But the highest solute concentration position is at the solidification front of the columnar grain zone near the cooling roll surface. Another solute enriched position is in the back flow above the nip point. Combined with the formation mechanism of microstruoture in final as cast strip, analysis shows that solute enriched area is in the transitional area between columnar and equiaxed grain zone.

摘要：In the case of the given design variables and constraint functions, this paper is concerned with the rapid overall parameters design of trajectory, propulsion and aerodynamics for long-range ballistic missiles based on the index of the minimum take-off *** contrast to the traditional subsystem independent design, this paper adopts the research idea of the combination of the subsystem independent design and the multisystem integration ***, the trajectory, propulsion and aerodynamics of the subsystem are separately designed by the engineering design, including the design of the minimum energy trajectory, the computation of propulsion system parameters, and the calculation of aerodynamic coefficient and dynamic derivative of the missile by employing the software of missile DATCOM. Then, the uniform design method is used to simplify the constraint conditions and the design variables through the integration design, and the accurate design of the optimized variables would be accomplished by adopting the uniform particle swarm optimization(PSO) algorithm. Finally, the automation design software is written for the three-stage solid ballistic missile. The take-off mass of 29 850 kg is derived by the subsystem independent design, and 20 constraints are reduced by employing the uniform design on the basis of 29 design variables and 32 constraints, and the take-off mass is dropped by 1 850 kg by applying the combination of the uniform design and PSO. The simulation results demonstrate the effectiveness and feasibility of the proposed hybrid optimization technique.

摘要：沥青胶砂-集料界面相的低温黏结性能对寒区沥青混合料的低温抗裂性、水稳性等性能有重要影响。基于拉拔试验并采用ImageJ软件对破坏面进行图像分析,通过黏结强度和黏结失效比2个指标,分析不同低温(-10、-20、-30℃)和有水条件下沥青、沥青胶浆、沥青砂浆与石灰岩集料组成的界面相黏结性能。研究结果表明,沥青-集料界面相在-20℃黏结强度最大,黏结失效比随着温度的降低在增大;水的介入会使界面相低温黏结强度的衰减率达到49%,界面连续脱落,黏结失效比增大44%;合适的粉胶比能提高沥青胶浆的低温黏结强度,粉胶比为1.2的沥青胶浆黏结强度为沥青基质的1.44倍,并通过弯曲蠕变劲度试验验证与沥青胶浆低温黏结强度结果的一致性;矿粉和细集料的加入改变了界面的接触形式,破坏位置和黏结失效比也发生了明显变化;沥青胶浆的破坏位置发生于胶浆内部,沥青砂浆的破坏位置多发生于界面处,其黏结失效比远大于沥青胶浆。

摘要：随着社会的不断发展,城市与山区公路在建设方面有着全新的发展。因为山区公路本身的特殊性,设计过程中在安全、环境保护以及行车舒适性等方面均有较高的要求,但是又因为环境本身的条件约束,导致在公路的规划与设计过程中存在许多的问题。对此,本文从山区公路设计现状着手,详细分析山区公路设计中存在且应当的主要问题,希望可以为今后相关工作提供理论性指导。

摘要：激素受体阳性/HER-2阴性(hormone receptor positive/HER-2 negative,HR+/HER2-)乳腺癌化疗敏感性差,新辅助化疗并未带来明显获益。新辅助内分泌治疗(neoadjuvant endocrine therapy,NET)可以取得与新辅助化疗相似的客观缓解率和更低的毒性,成为一种有效的替代手段。同时,CDK4/6抑制剂改变了HR+/HER2-乳腺癌的治疗格局,对NET的优化选择提出了新的临床问题。在临床实践中应依据肿瘤生物学、疗效与肿瘤负荷,采用适应性研究设计,优化患者治疗策略,进行个体化、精准化治疗。本文就NET的应用价值、疗效评估及联合治疗等方面进行综述。

摘要：《水土保持规划编制规范》(SL/T 335—2024)经水利部2024年第19号公告发布,于2024年11月24日正式实施。此次修订是在系统总结原标准执行情况的基础上,根据新形势和新要求,以存在的问题和需求为导向,衔接协调相关规划编制要求,经过充分讨论、广泛征求意见和咨询专家后系统开展的。修订后进一步明确了水土保持规划分类,优化了标准框架结构,深化细化了标准内容。修订后的标准对规范新时期水土保持规划编制工作具有重要意义,将进一步健全全国水土保持规划体系,推动水土保持高质量发展。

摘要：文章以某航空维修基地项目实施为基础,针对项目方案对混凝土材料提出的表观质量和高抛免振捣的特殊性能与施工要求,从高抛免振捣清水混凝土配置、施工过程及管控要点、实施效果等方面介绍了高抛免振捣清水混凝土技术的应用要点,以供同类工程参考。

摘要：Very high flow coefficient centrifugal compressor stages are mostly performance of this type of stages is critical to the entire centrifugal applied as the first stages of multistage compressors. The compressors, but surprisingly little related information is available in the open literature. A centrifugal compressor with high inlet flow coefficient of 0.2, presenting a narrow operating range and unstable running situation even at design speed during the test, is investigated here. To reveal flow details in this centrifugal compressor, numerical simulations have been carried out and indicate that excessive impeller flow diffusion results in the poor performance of this centrifugal compressor. With the same inlet flow coefficient, six redesign cases coming from an in-house one-dimensional analysis program are proposed together with impeller trimming and equal flow area design method for corresponding vaneless diffuser. Performance comparison among these redesign centrifugal compressors is presented and the most suitable one is recommended for test in the future. In addition, three redesign cases with lower inlet flow coefficient developed by means of flow trimming are shown in the end to satisfy potential application areas. Finally, the results in this study can provide valuable reference information for multistage centrifugal compressor design.

摘要：在储层钻探开发过程中,准确提取、识别与评价地层中的裂缝对指导油气勘探的钻探和开发具有重要意义.针对传统方法对裂缝区域分割不精细的问题,提出一种基于深度学习的FMI(Formation Micro-Scanner Image)测井图像裂缝分割方法.首先,利用F-Criminisi算法对原始FMI测井图像中缺失像素信息的空白条带进行图像修复.接着构建以U-Net为基础的生成对抗网络,并引入双重注意力机制,构建裂缝分割模型,实现复杂背景下对裂缝的精确分割,结合像素与边缘信息设计损失函数,使模型更准确分割测井图像中的裂缝与背景区域,使分割结果中的裂缝边界更清晰.本文利用实测碳酸盐岩储层FMI测井图像对提出的模型进行了测试.结果表明,所提裂缝分割方法的Dice系数相较于经典的分割模型U-Net提升5%.该方法能够精确地提取FMI测井图像中的裂缝信息,为后续裂缝参数的定量计算和测井解译提供了基础,具备较强的实用性.