Building a grid-semantic map for the navigation of service robots through human–robot interaction

AbstractThis paper presents an interactive approach to the construction of a grid-semantic map for the navigation of service robots in an indoor environment. It is based on the Robot Operating System (ROS) framework and contains four modules, namely Interactive Module, Control Module, Navigation Module and Mapping Module. Three challenging issues have been focused during its development: (i) how human voice and robot visual information could be effectively deployed in the mapping and navigation process; (ii) how semantic names could combine with coordinate data in an online Grid-Semantic map; and (iii) how a localization–evaluate–relocalization method could be used in global localization based on modified maximum particle weight of the particle swarm. A number of experiments are carried out in both simulated and real environments such as corridors and offices to verify its feasibility and performance

Morphology in the total electron content under geomagnetic disturbed conditions: results from global ionosphere maps

International audienceUsing 8-year global ionosphere maps (GIMs) of TEC products from the Jet Propulsion Laboratory (JPL), we make a statistical study on the morphology of the global ionospheric behaviors with respect to the geomagnetic disturbances. Results show that the behaviors of TEC during geomagnetic storm present clear seasonal and local time variations under geomagnetic control in a similar way as those of NmF2 (Field and Rishbeth, 1997). A negative phase of TEC occurs with high probability in the summer hemisphere and most prominent near the geomagnetic poles, while a positive phase is obvious in the winter hemisphere and in the far pole region. A negative storm effect toward lower latitudes tends to occur from post-midnight to the morning sector and recedes to high latitude in the afternoon. A positive storm effect is separated by geomagnetic latitudes and magnetic local time. Furthermore, ionospheric responses at different local time sectors with respect to the storm commencement shows very different developing processes corresponding to the evolution of the geomagnetic storm. A daytime positive storm effect is shown to be more prominent in the American region than those in the Asian and European regions, which may suggest a longitudinal effect of the ionospheric storm

On-line detection method for outliers of dynamic instability measurement data in geological exploration control process

Considering the characteristics of the vibration data detected by the unstable regulation process in the grinding and grading control system and the shortcomings of the traditional wavelet anomaly detection method, an online anomaly detection method combining autoregressive and wavelet analysis is proposed. By introducing the improved robust AR model, this method can overcome the problem that the time and frequency of traditional anomaly detection using wavelet analysis method cannot be well balanced and ensure the rationality of normal detection of process data. Considering the characteristics of parameter change and dynamic characteristics in the process of grinding and grading, the proposed method has the ability of on-line detection and parameter updating in real time, which ensures the control parameters of time-varying process control system. In order to avoid the problem that the traditional anomaly detection method needs to set the detection threshold, introduce the HMM to analyse the wavelet coefficients and update the HMM parameters online, which can ensure that the HMM can well reflect the distribution of the abnormal value of the process data. Through the experiment and application, it is proven that the anomaly data detection method proposed in this paper is more suitable for the detection data in the process of unstable regulation

Model shape correction method for high-frequency force balance technique

This study proposed the mode shape correction formulae for the high frequency force balance technique. The presented formulae respectively give the mode shape for translational modes and torsional modes, meaning that there is no need to distinguish the traditionally concerned along wind case and cross-wind case anymore. This treatment makes the mode shape correction much simpler especially when wind blows to a building obliquely. Comparison with some experimental results of other researchers shows the reliability of the proposed formulae. The mode coupling effect is also analyzed and discussed through an actual super-tall building, the Guangzhou East Tower. The results show that the mode shape coupling effect is significant and cannot be ignored

Research on vehicle handling inverse dynamics based on optimal control while encountering emergency collision avoidance

Vehicle driving safety is the urgent key problem to be solved of vehicle independent development while encountering emergency collision avoidance with high speed. And it is also the premise and one of the necessary conditions of vehicle active safety. A new technique for vehicle handling inverse dynamics which can evaluate the emergency collision avoidance performance is proposed. Firstly, the steering angle input of 3-DOF vehicle mode is established. The steering angle input imposed by driver is the control variable, and accurately tracking the expected path was the control object. The optimal control problem can be converted into a nonlinear programming problem while using the state variables conversion, which was solved by the sequential quadratic programming (SQP) algorithm. The results show that vehicle can well track the expected path in high speed

Global scale annual and semi-annual variations of daytime NmF2 in the high solar activity years

Abstract The annual and semi-annual variations of the ionosphere are investigated in the present paper by using the daytime F2 layer peak electron concentration (NmF2) observed at a global ionosonde network with 104 stations. The main features are outlined as follows

A Systematic Survey of General Sparse Matrix-Matrix Multiplication

SpGEMM (General Sparse Matrix-Matrix Multiplication) has attracted much attention from researchers in fields of multigrid methods and graph analysis. Many optimization techniques have been developed for certain application fields and computing architecture over the decades. The objective of this paper is to provide a structured and comprehensive overview of the research on SpGEMM. Existing optimization techniques have been grouped into different categories based on their target problems and architectures. Covered topics include SpGEMM applications, size prediction of result matrix, matrix partitioning and load balancing, result accumulating, and target architecture-oriented optimization. The rationales of different algorithms in each category are analyzed, and a wide range of SpGEMM algorithms are summarized. This survey sufficiently reveals the latest progress and research status of SpGEMM optimization from 1977 to 2019. More specifically, an experimentally comparative study of existing implementations on CPU and GPU is presented. Based on our findings, we highlight future research directions and how future studies can leverage our findings to encourage better design and implementation.Comment: 19 pages, 11 figures, 2 tables, 4 algorithm

Predictive Value of Hemodynamic Indicators for Bronchopulmonary Dysplasia in Preterm Infants

BackgroundIn China, the growing prevalence of bronchopulmonary dysplasia (BPD) in increased number of survived very preterm and extremely preterm infants, seriously endangers the life and impairs quality of life in this population. There are different degrees of hemodynamic changes in preterm infants in the process of developing BPD, however, there are relatively few studies about the correlation between the occurrence of BPD and hemodynamic indicators in preterm infant.ObjectiveTo examine predictive value of the hemodynamic indexes for BPD in premature infants.MethodsOne hundred and sixty-one premature infants (hospitalized within 1 hour of birth, gestational age <32 weeks) were selected from Xinxiang Central Hospital from September 2018 to December 2020. The general data (gestational age, birth weight, sex, and mode of delivery) were collected; the basic diseases and other complications of preterm infants were collected, compared between two groups of infants divided by the prevalence of BPD (n=65) or not (n=96) . PI values (measured at 1, 12, 48, 72 and 96 hours after delivery, and on the 5th, 6th, and 7th days after delivery, respectively) , and serum lactic acid levels (measured at 1, 12, and 24 hours after admission, respectively) were collected. Mean arterial pressure (MAP) levels measured by arterial pressure monitoring at 1, 12 and 24 hours after admission for 33 infants (16 in BPD group and 17 in the control group) with critical or extremely critical conditions suggested by neonatal critical illness score were also collected. Compare the results between two groups, the receiver operating characteristic (ROC) curve was plotted to evaluate the predictive value of PI, serum lactic acid and MAP for BPD in preterm infants.ResultsSixty-five out of the 161 cases 〔40.3% (65/161) 〕were diagnosed with BPD. Preterm infants with and without BPD had no statistically significant differences in gestational age, birth weight, gender, and mode of delivery (P>0.05) . Preterm infants with BPD had higher incidence of neonatal asphyxia, neonatal respiratory distress syndrome, neonatal pneumonia, and retinopathy of prematurity than those without (P<0.05) . Preterm infants with and without BPD had no statistically significant differences in sepsis, pulmonary hemorrhage, PDA, IVH, purulent meningitis and anemia (P>0.05) . PI values at 1, 12 and 24 hours after birth differed significantly between the two groups (P<0.05) . Serum lactic acid at 1 hour after admission differed significant between the two groups (P<0.05) . MAP levels at different time periods showed no significant differences between critical and extremely critical preterm infants with and without BPD (P>0.05) . In predicting BPD, the PI at 1-hour, 12-hour, and 24-hour was 0.847〔95%CI (0.788, 0.906) , P<0.001〕, 0.776〔95%CI (0.705, 0.846) , P<0.001〕, 0.695〔95%CI (0.613, 0.778) , P<0.001〕, respectively; the optimal cutoff value was chosen as 0.55, 1.15, 1.45, with the sensitivity of 76.9%, 86.2%, 81.5% and the specificity of 75.0%, 60.4%, 51.0%; serum lactic acid at 1 hour after birthhad an AUC of 0.762〔95%CI (0.686, 0.837) , P<0.001〕, the optimal cutoff value was chosen as 6.55, with the sensitivity of 81.5%, and the specificity of 68.7%.ConclusionIn preterm infants with a gestational age <32 weeks, the change of hemodynamic indicatou PI and lactic acid value maybe correlated with the occurrence of BPD. PI value within 24 hours after birth may be an earlypredictor for BPD, but further research is still needed