摘要：In spacecraft electronic devices,the deformation of solder balls within ball grid array(BGA)packages poses a significant risk of system ***,accurately measuring the mechanical behavior of solder balls is crucial for ensuring the safety and reliability of *** finite element simulations have been extensively used to study solder ball deformation,there is a significant lack of experimental validation,particularly under thermal cycling *** is due to the challenges in accurately measuring the internal deformations of solder balls and eliminating the rigid body displacement introduced during ex-situ thermal cycling *** this work,an ex-situ three-dimensional deformation measurement method using X-ray computed tomography(CT)and digital volume correlation(DVC)is proposed to overcome these *** incorporating the layer-wise reliability-guided displacement tracking(LW-RGDT)DVC with a singular value decomposition(SVD)method,this method enables accurate assessment of solder ball mechanical behavior in BGA packages without the influence of rigid body *** results reveal that BGA structures exhibit progressive convex deformation with increased thermal cycling,particularly in peripheral solder *** method provides a reliable and effective tool for assessing internal deformations in electronic packages under ex-situ conditions,which is crucial for their design optimization and lifespan predictions.

摘要：依托可视化多相流实验平台,利用储罐温度控制流体黏度,开展垂直管较高黏度油气两相流动特性实验研究。记录不同黏度(60、100、290、480 mPa·s)、表观气速(1~60 m/s)和表观液速(0.02~0.55 m/s)下管内流型、持液率和压降,得到156组实验数据,分析不同黏度液体对气液两相流动的影响和现有模型产生误差的主要原因。结果表明:总压降随着液体黏度的增加而增加,随着表观气速的增大先减小后增大;总压降最小值受表观液速及其黏度的共同影响。根据实验数据重新拟合了压降预测模型,采用10井次生产数据对新模型验证的平均绝对误差(mean absolute deviation,MAD)值为13.48%,较其他预测模型准确度提高了10%,新模型能够为稠油生产和运输设计提供理论参考。

摘要：新能源发电的大规模并网,造成电网转动惯量整体比重下降,对AGC系统的控制性能提出了更高的要求。为提升AGC系统的动态性能,首先,设计非线性函数并和传统PI控制器串联形成非线性PI控制器,改善了传统AGC控制器由于参数固化而对负荷波动显现的不适应性;其次,为求取非线性PI控制器最优参数,对传统粒子群算法进行改进,将混沌理论融入优化算法中,增强了种群的全局搜索能力和粒子多样性。以双区域互联电网AGC系统为研究对象,验证了所提方法的可行性和有效性。

摘要：线夹在电网系统中占据着关键的位置,其性能和稳定性直接关系到电网的安全与稳定。对线夹的常见问题、技术创新与建议、实践指导进行了深入探讨。经过研究,提出了一系列的技术创新和改进策略,如选择新型合金、优化设计、改进制造工艺以及引入现代化的监测和预警系统。还建议电网维护和管理部门强化线夹的日常管理,而线夹的设计和制造商则需持续进行技术培训和质量控制以满足日益增长的市场需求。总之,为确保电网的长期稳定运行,对线夹的研究、创新和改进是至关重要的。