A critical component of visual simultaneous localization and mapping is loop closure detection(LCD),an operation judging whether a robot has come to a pre-visited area.Concretely,given a query image(i.e.,the latest vi...A critical component of visual simultaneous localization and mapping is loop closure detection(LCD),an operation judging whether a robot has come to a pre-visited area.Concretely,given a query image(i.e.,the latest view observed by the robot),it proceeds by first exploring images with similar semantic information,followed by solving the relative relationship between candidate pairs in the 3D space.In this work,a novel appearance-based LCD system is proposed.Specifically,candidate frame selection is conducted via the combination of Superfeatures and aggregated selective match kernel(ASMK).We incorporate an incremental strategy into the vanilla ASMK to make it applied in the LCD task.It is demonstrated that this setting is memory-wise efficient and can achieve remarkable performance.To dig up consistent geometry between image pairs during loop closure verification,we propose a simple yet surprisingly effective feature matching algorithm,termed locality preserving matching with global consensus(LPM-GC).The major objective of LPM-GC is to retain the local neighborhood information of true feature correspondences between candidate pairs,where a global constraint is further designed to effectively remove false correspondences in challenging sceneries,e.g.,containing numerous repetitive structures.Meanwhile,we derive a closed-form solution that enables our approach to provide reliable correspondences within only a few milliseconds.The performance of the proposed approach has been experimentally evaluated on ten publicly available and challenging datasets.Results show that our method can achieve better performance over the state-of-the-art in both feature matching and LCD tasks.We have released our code of LPM-GC at https://github.com/jiayi-ma/LPM-GC.展开更多
A novel structure for a charge pump circuit is proposed, in which the charge-pump （CP） current can adaptively regulated according to phase-locked loops （PLL） frequency synthesis demand. The current follow technolo...A novel structure for a charge pump circuit is proposed, in which the charge-pump （CP） current can adaptively regulated according to phase-locked loops （PLL） frequency synthesis demand. The current follow technology is used to make perfect current matching characteristics, and the two differential inverters are implanted to increase the speed of charge pump and decrease output spur due to theory of low voltage difference signal. Simulation results, with 1st silicon 0. 25μm 2. 5 V complementary metal-oxide-semiconductor （CMOS） mixed-signal process, show the good current matching characteristics regardless of the charge pump output voltages.展开更多
The closed-loop reservoir management technique enables a dynamic and real-time optimal production schedule under the existing reservoir conditions to be achieved by adjusting the injection and production strategies. T...The closed-loop reservoir management technique enables a dynamic and real-time optimal production schedule under the existing reservoir conditions to be achieved by adjusting the injection and production strategies. This is one of the most effective ways to exploit limited oil reserves more economically and efficiently. There are two steps in closed-loop reservoir management： automatic history matching and reservoir production opti- mization. Both of the steps are large-scale complicated optimization problems. This paper gives a general review of the two basic techniques in closed-loop reservoir man- agement; summarizes the applications of gradient-based algorithms, gradient-free algorithms, and artificial intelligence algorithms; analyzes the characteristics and application conditions of these optimization methods; and finally discusses the emphases and directions of future research on both automatic history matching and reservoir production optimization.展开更多
The interference reduction capability of antenna arrays and the power control algorithms have been considered separately as means to decrease the interference in wireless communication networks. In this paper, we prop...The interference reduction capability of antenna arrays and the power control algorithms have been considered separately as means to decrease the interference in wireless communication networks. In this paper, we propose smart step closed-loop power control (SSPC) algorithm in wireless networks in a 2D urban environment with constrained least mean squared (CLMS) algorithm. This algorithm is capable of efficiently adapting according to the environment and able to permanently maintain the chosen frequency response in the look direction while minimizing the output power of the array. Also, we present switched-beam (SB) technique for enhancing signal to interference plus noise ratio (SINR) in wireless networks. Also, we study an analytical approach for the evaluation of the impact of power control error (PCE) on wireless networks in a 2D urban environment. The simulation results indicate that the convergence speed of the SSPC algorithm is faster than other algorithms. Also, we observe that significant saving in total transmit power (TTP) are possible with our proposed algorithm. Finally, we discuss three parameters of the PCE, number of antenna elements, and path-loss exponent and their effects on capacity of the system via some computer simulations.展开更多
针对停车场视觉建图的回环检测方法对目标级别的语义信息关注较少、在长时间大范围的建图过程中地图一致性与持久性较差的问题,设计了一种语义回环检测算法。该算法基于语义实例,使用图匹配方法找到回环帧并进行帧间位姿估计,生成回环...针对停车场视觉建图的回环检测方法对目标级别的语义信息关注较少、在长时间大范围的建图过程中地图一致性与持久性较差的问题,设计了一种语义回环检测算法。该算法基于语义实例,使用图匹配方法找到回环帧并进行帧间位姿估计,生成回环约束。在同准确率下,该回环检测算法的召回率均高于基于ORB(oriented fast and rotate brief)描述子和词袋法的回环检测方案。在停车场建图与定位试验中,建图轨迹与轨迹真值的绝对误差均小于1 m,定位误差均小于0.3 m,满足对应的技术要求。试验结果表明,本文提出的语义回环检测算法的回环检测性能优于传统回环检测算法,适用于停车场视觉建图任务。展开更多
基金supported by the Key Research and Development Program of Hubei Province(2020BAB113)。
文摘A critical component of visual simultaneous localization and mapping is loop closure detection(LCD),an operation judging whether a robot has come to a pre-visited area.Concretely,given a query image(i.e.,the latest view observed by the robot),it proceeds by first exploring images with similar semantic information,followed by solving the relative relationship between candidate pairs in the 3D space.In this work,a novel appearance-based LCD system is proposed.Specifically,candidate frame selection is conducted via the combination of Superfeatures and aggregated selective match kernel(ASMK).We incorporate an incremental strategy into the vanilla ASMK to make it applied in the LCD task.It is demonstrated that this setting is memory-wise efficient and can achieve remarkable performance.To dig up consistent geometry between image pairs during loop closure verification,we propose a simple yet surprisingly effective feature matching algorithm,termed locality preserving matching with global consensus(LPM-GC).The major objective of LPM-GC is to retain the local neighborhood information of true feature correspondences between candidate pairs,where a global constraint is further designed to effectively remove false correspondences in challenging sceneries,e.g.,containing numerous repetitive structures.Meanwhile,we derive a closed-form solution that enables our approach to provide reliable correspondences within only a few milliseconds.The performance of the proposed approach has been experimentally evaluated on ten publicly available and challenging datasets.Results show that our method can achieve better performance over the state-of-the-art in both feature matching and LCD tasks.We have released our code of LPM-GC at https://github.com/jiayi-ma/LPM-GC.
文摘A novel structure for a charge pump circuit is proposed, in which the charge-pump （CP） current can adaptively regulated according to phase-locked loops （PLL） frequency synthesis demand. The current follow technology is used to make perfect current matching characteristics, and the two differential inverters are implanted to increase the speed of charge pump and decrease output spur due to theory of low voltage difference signal. Simulation results, with 1st silicon 0. 25μm 2. 5 V complementary metal-oxide-semiconductor （CMOS） mixed-signal process, show the good current matching characteristics regardless of the charge pump output voltages.
基金the Important National Science & Technology Specific Projects of China (Grant No. 2011ZX05024-004)the Natural Science Foundation for Distinguished Young Scholars of Shandong Province, China (Grant No. JQ201115)+2 种基金the Program for New Century Excellent Talents in University (Grant No. NCET-11-0734)the Fundamental Research Funds for the Central Universities (Grant No. 13CX05007A, 13CX05016A)the Program for Changjiang Scholars and Innovative Research Team in University (IRT1294)
文摘The closed-loop reservoir management technique enables a dynamic and real-time optimal production schedule under the existing reservoir conditions to be achieved by adjusting the injection and production strategies. This is one of the most effective ways to exploit limited oil reserves more economically and efficiently. There are two steps in closed-loop reservoir management： automatic history matching and reservoir production opti- mization. Both of the steps are large-scale complicated optimization problems. This paper gives a general review of the two basic techniques in closed-loop reservoir man- agement; summarizes the applications of gradient-based algorithms, gradient-free algorithms, and artificial intelligence algorithms; analyzes the characteristics and application conditions of these optimization methods; and finally discusses the emphases and directions of future research on both automatic history matching and reservoir production optimization.
文摘The interference reduction capability of antenna arrays and the power control algorithms have been considered separately as means to decrease the interference in wireless communication networks. In this paper, we propose smart step closed-loop power control (SSPC) algorithm in wireless networks in a 2D urban environment with constrained least mean squared (CLMS) algorithm. This algorithm is capable of efficiently adapting according to the environment and able to permanently maintain the chosen frequency response in the look direction while minimizing the output power of the array. Also, we present switched-beam (SB) technique for enhancing signal to interference plus noise ratio (SINR) in wireless networks. Also, we study an analytical approach for the evaluation of the impact of power control error (PCE) on wireless networks in a 2D urban environment. The simulation results indicate that the convergence speed of the SSPC algorithm is faster than other algorithms. Also, we observe that significant saving in total transmit power (TTP) are possible with our proposed algorithm. Finally, we discuss three parameters of the PCE, number of antenna elements, and path-loss exponent and their effects on capacity of the system via some computer simulations.
文摘针对停车场视觉建图的回环检测方法对目标级别的语义信息关注较少、在长时间大范围的建图过程中地图一致性与持久性较差的问题,设计了一种语义回环检测算法。该算法基于语义实例,使用图匹配方法找到回环帧并进行帧间位姿估计,生成回环约束。在同准确率下,该回环检测算法的召回率均高于基于ORB(oriented fast and rotate brief)描述子和词袋法的回环检测方案。在停车场建图与定位试验中,建图轨迹与轨迹真值的绝对误差均小于1 m,定位误差均小于0.3 m,满足对应的技术要求。试验结果表明,本文提出的语义回环检测算法的回环检测性能优于传统回环检测算法,适用于停车场视觉建图任务。
