L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正...L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正交投影干扰抑制与单快拍稀疏分解的波达方向(direction of arrival,DOA)估计方法。通过子空间投影抑制DME干扰,然后使用单快拍数据构建伪协方差矩阵,对伪协方差矩阵求高阶幂,之后进行奇异值分解,并利用约束条件求解稀疏解得到期望信号来向的估计值。所提方法使用高阶伪协方差矩阵降低了噪声影响,仅用单快拍就可以准确估计LDACS信号的入射方向。仿真结果表明,改进单快拍高级幂(improved single snapshot high order power,ISS-HOP)L1-SVD算法的估计精度优于ISS-HOP-MUSIC算法。该方法可以有效抑制DME干扰,提高OFDM接收机性能。展开更多
针对L波段数字航空通信系统(L-band digital aeronautic communication system,LDACS)可用频谱资源有限且易受大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出一种基于降维循环谱和残差神经网络的频谱感知方法。首...针对L波段数字航空通信系统(L-band digital aeronautic communication system,LDACS)可用频谱资源有限且易受大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出一种基于降维循环谱和残差神经网络的频谱感知方法。首先理论推导分析了DME信号的循环谱特征;然后利用Fisher判别率(Fisher discriminant rate,FDR)提取循环频率能量最大的向量,通过主成分分析(principal component analysis,PCA)进行预处理特征增强;最后给出数据处理后的循环谱向量与卷积神经网络相结合的实现过程,实现了DME信号的有效检测。仿真结果表明,该方法对噪声不敏感,当信噪比不低于-15 dB时,平均检测概率大于90%。当信噪比不低于-14 dB,检测概率接近100%。展开更多
目的:探讨基于CT三维重组技术的R.E.N.A.L.评分系统在腹腔镜肾部分切除术中的临床应用价值。方法:搜集我院2020年6月至2024年1月经手术治疗的79例肾肿瘤患者的临床及术前影像资料,根据术前肾脏CT三维重组结果,分析血管变异与肾脏热缺血...目的:探讨基于CT三维重组技术的R.E.N.A.L.评分系统在腹腔镜肾部分切除术中的临床应用价值。方法:搜集我院2020年6月至2024年1月经手术治疗的79例肾肿瘤患者的临床及术前影像资料,根据术前肾脏CT三维重组结果,分析血管变异与肾脏热缺血时间、手术总时间、术中出血量及术后并发症之间的关系,并进行R.E.N.A.L.评分。采用Logistic回归筛选出肾热缺血时间大于20 min的独立危险因素。结果:有无血管变异在肾脏热缺血时间、手术总时间、术中出血量及术后并发症之间无明显差异(P > 0.05)。R.E.N.A.L.总评分是肾热缺血时间大于20 min的独立危险因素(P P Objective: To explore the clinical application value of R.E.N.A.L. scoring system based on CT three-dimensional reconstruction technology in laparoscopic partial nephrectomy. Methods: The clinical and preoperative imaging data of 79 patients with renal tumors who underwent surgical treatment in our hospital from June 2020 to January 2024 were collected. According to the results of preoperative renal CT three-dimensional reconstruction, the relationship between vascular variation and renal warm ischemia time, total operation time, intraoperative bleeding and postoperative complications was analyzed, and R.E.N.A.L. score was performed. Logistic regression was used to screen out independent risk factors for renal warm ischemia time greater than 20 min. Results: There was no significant difference in renal warm ischemia time, total operation time, intraoperative blood loss and postoperative complications between the presence or absence of vascular variation (P > 0.05). The total R.E.N.A.L. score was an independent risk factor for renal warm ischemia time greater than 20 min (P P < 0.05). Conclusion: CT three-dimensional reconstruction can clearly understand the anatomical location of the kidney, tumor and blood vessels before surgery, thereby reducing the occurrence of perioperative complications.展开更多
文摘L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正交投影干扰抑制与单快拍稀疏分解的波达方向(direction of arrival,DOA)估计方法。通过子空间投影抑制DME干扰,然后使用单快拍数据构建伪协方差矩阵,对伪协方差矩阵求高阶幂,之后进行奇异值分解,并利用约束条件求解稀疏解得到期望信号来向的估计值。所提方法使用高阶伪协方差矩阵降低了噪声影响,仅用单快拍就可以准确估计LDACS信号的入射方向。仿真结果表明,改进单快拍高级幂(improved single snapshot high order power,ISS-HOP)L1-SVD算法的估计精度优于ISS-HOP-MUSIC算法。该方法可以有效抑制DME干扰,提高OFDM接收机性能。
文摘目的:探讨基于CT三维重组技术的R.E.N.A.L.评分系统在腹腔镜肾部分切除术中的临床应用价值。方法:搜集我院2020年6月至2024年1月经手术治疗的79例肾肿瘤患者的临床及术前影像资料,根据术前肾脏CT三维重组结果,分析血管变异与肾脏热缺血时间、手术总时间、术中出血量及术后并发症之间的关系,并进行R.E.N.A.L.评分。采用Logistic回归筛选出肾热缺血时间大于20 min的独立危险因素。结果:有无血管变异在肾脏热缺血时间、手术总时间、术中出血量及术后并发症之间无明显差异(P > 0.05)。R.E.N.A.L.总评分是肾热缺血时间大于20 min的独立危险因素(P P Objective: To explore the clinical application value of R.E.N.A.L. scoring system based on CT three-dimensional reconstruction technology in laparoscopic partial nephrectomy. Methods: The clinical and preoperative imaging data of 79 patients with renal tumors who underwent surgical treatment in our hospital from June 2020 to January 2024 were collected. According to the results of preoperative renal CT three-dimensional reconstruction, the relationship between vascular variation and renal warm ischemia time, total operation time, intraoperative bleeding and postoperative complications was analyzed, and R.E.N.A.L. score was performed. Logistic regression was used to screen out independent risk factors for renal warm ischemia time greater than 20 min. Results: There was no significant difference in renal warm ischemia time, total operation time, intraoperative blood loss and postoperative complications between the presence or absence of vascular variation (P > 0.05). The total R.E.N.A.L. score was an independent risk factor for renal warm ischemia time greater than 20 min (P P < 0.05). Conclusion: CT three-dimensional reconstruction can clearly understand the anatomical location of the kidney, tumor and blood vessels before surgery, thereby reducing the occurrence of perioperative complications.
