水下小型声探测系统因具有体积小、重量轻的特点易装载于航空反潜机动平台上。新型水下小尺寸扩展式基阵声探测系统不仅具有航空用探测设备的特点又兼具扩展后可以形成更大的孔径尺寸,有效地提高系统灵敏度、阵处理增益和定向精度等优势...水下小型声探测系统因具有体积小、重量轻的特点易装载于航空反潜机动平台上。新型水下小尺寸扩展式基阵声探测系统不仅具有航空用探测设备的特点又兼具扩展后可以形成更大的孔径尺寸,有效地提高系统灵敏度、阵处理增益和定向精度等优势,必将发展为现代反潜战中较为有效的探潜手段之一。结合研制的新型水下小尺寸扩展式基阵声探测系统,开展了工程用系统定向性能水池实验研究。系统设计前端基于模拟退火波束优化算法,中心频率下实测全景波束较优,逼近-30 d B期望旁瓣级的设计要求。后端通过合理的多波束比幅测向算法得到了较好的定向性能,能够满足<3°标准差的指标。实测的定向结果验证了该型水下小尺寸扩展式基阵声探测系统的工程实用性,也为进一步开展工程有效性和稳定性的研究提供了前期的实验参考。展开更多
In this paper, we focus on energy-efficient transceiver and relay beamforming design for multi-pair two-way relay system. The multi-antenna users and the multi-antenna relay are considered in this work. Different from...In this paper, we focus on energy-efficient transceiver and relay beamforming design for multi-pair two-way relay system. The multi-antenna users and the multi-antenna relay are considered in this work. Different from the existing works, the proposed algorithm is energy-efficient which is more applicable to the future green network. It considers both the sum-MSE problem and the power consumption problem for the users under the relay power constraint. Based on the optimal condition decomposition(OCD) method, the energy-efficient precoders at the users can be designed separately with limited information exchanged. The proposed relay beamforming algorithm is based on the alternative direction method of multipliers(ADMM) which has simpler iterative solution and enjoys good convergence. Simulation results demonstrate the performance of the proposed algorithms in terms of power consumption and MSE performance.展开更多
本文在结合分析已有的三种技术成熟的声纳系统:干涉侧扫声呐、多波束测深声呐和合成孔径声呐的核心技术及 主要功能特点的基础上,在硬件方面创新设计出一种基于多波束测深和合成孔径技术原理的多波束阵列结构,在方位向采样 间距过大时,...本文在结合分析已有的三种技术成熟的声纳系统:干涉侧扫声呐、多波束测深声呐和合成孔径声呐的核心技术及 主要功能特点的基础上,在硬件方面创新设计出一种基于多波束测深和合成孔径技术原理的多波束阵列结构,在方位向采样 间距过大时,剔除图像中伪目标,提高成像准确率;软件方面,团队创新提出结合 n 阶 AR 数学模型和卡尔曼滤波法的多波 束等效相位中心法,尝试解决现有声纳成像多用的的等效相位中心法存在的二维运动近似误差和估计误差积累问题。展开更多
After grouting the ducts in a large band beam and one-way slab post-tensioned floor system in a large shopping mall （in excess of 1.5 km2 in plan）, doubts arose concerning the level of initial prestress and the stre...After grouting the ducts in a large band beam and one-way slab post-tensioned floor system in a large shopping mall （in excess of 1.5 km2 in plan）, doubts arose concerning the level of initial prestress and the strength and serviceability of the slabs was questioned. To assess the strength of the slabs, it was assumed, as a worst case scenario, that some spans may have been constructed with zero initial prestress. Load tests on prototype specimens, with similar dimensions and reinforcement quantities as the floor slabs, were performed to assess the stress development in initially unstressed, but fully grouted, tendons. Unexpected bond failures occurred at the junctions of slab and band beam where the abrupt change in section depth caused a sudden change in tendon stress. The maximum stress that was developed in the initially unstressed tendons at these locations was about 60% of the strength of the tendons.展开更多
文摘水下小型声探测系统因具有体积小、重量轻的特点易装载于航空反潜机动平台上。新型水下小尺寸扩展式基阵声探测系统不仅具有航空用探测设备的特点又兼具扩展后可以形成更大的孔径尺寸,有效地提高系统灵敏度、阵处理增益和定向精度等优势,必将发展为现代反潜战中较为有效的探潜手段之一。结合研制的新型水下小尺寸扩展式基阵声探测系统,开展了工程用系统定向性能水池实验研究。系统设计前端基于模拟退火波束优化算法,中心频率下实测全景波束较优,逼近-30 d B期望旁瓣级的设计要求。后端通过合理的多波束比幅测向算法得到了较好的定向性能,能够满足<3°标准差的指标。实测的定向结果验证了该型水下小尺寸扩展式基阵声探测系统的工程实用性,也为进一步开展工程有效性和稳定性的研究提供了前期的实验参考。
基金supported by China National S&T Major Project 2013ZX03003002-003National Natural Science Foundation of China under Grant No. 61176027, No.61421001111 Project of China under Grant B14010
文摘In this paper, we focus on energy-efficient transceiver and relay beamforming design for multi-pair two-way relay system. The multi-antenna users and the multi-antenna relay are considered in this work. Different from the existing works, the proposed algorithm is energy-efficient which is more applicable to the future green network. It considers both the sum-MSE problem and the power consumption problem for the users under the relay power constraint. Based on the optimal condition decomposition(OCD) method, the energy-efficient precoders at the users can be designed separately with limited information exchanged. The proposed relay beamforming algorithm is based on the alternative direction method of multipliers(ADMM) which has simpler iterative solution and enjoys good convergence. Simulation results demonstrate the performance of the proposed algorithms in terms of power consumption and MSE performance.
文摘本文在结合分析已有的三种技术成熟的声纳系统:干涉侧扫声呐、多波束测深声呐和合成孔径声呐的核心技术及 主要功能特点的基础上,在硬件方面创新设计出一种基于多波束测深和合成孔径技术原理的多波束阵列结构,在方位向采样 间距过大时,剔除图像中伪目标,提高成像准确率;软件方面,团队创新提出结合 n 阶 AR 数学模型和卡尔曼滤波法的多波 束等效相位中心法,尝试解决现有声纳成像多用的的等效相位中心法存在的二维运动近似误差和估计误差积累问题。
文摘After grouting the ducts in a large band beam and one-way slab post-tensioned floor system in a large shopping mall （in excess of 1.5 km2 in plan）, doubts arose concerning the level of initial prestress and the strength and serviceability of the slabs was questioned. To assess the strength of the slabs, it was assumed, as a worst case scenario, that some spans may have been constructed with zero initial prestress. Load tests on prototype specimens, with similar dimensions and reinforcement quantities as the floor slabs, were performed to assess the stress development in initially unstressed, but fully grouted, tendons. Unexpected bond failures occurred at the junctions of slab and band beam where the abrupt change in section depth caused a sudden change in tendon stress. The maximum stress that was developed in the initially unstressed tendons at these locations was about 60% of the strength of the tendons.
