Comparative Study of Different Methods in Vibration-Based Terrain Classification for Wheeled Robots with Shock Absorbers

open access articleAutonomous robots that operate in the field can enhance their security and efficiency by accurate terrain classification, which can be realized by means of robot-terrain interaction-generated vibration signals. In this paper, we explore the vibration-based terrain classification (VTC), in particular for a wheeled robot with shock absorbers. Because the vibration sensors are usually mounted on the main body of the robot, the vibration signals are dampened significantly, which results in the vibration signals collected on different terrains being more difficult to discriminate. Hence, the existing VTC methods applied to a robot with shock absorbers may degrade. The contributions are two-fold: (1) Several experiments are conducted to exhibit the performance of the existing feature-engineering and feature-learning classification methods; and (2) According to the long short-term memory (LSTM) network, we propose a one-dimensional convolutional LSTM (1DCL)-based VTC method to learn both spatial and temporal characteristics of the dampened vibration signals. The experiment results demonstrate that: (1) The feature-engineering methods, which are efficient in VTC of the robot without shock absorbers, are not so accurate in our project; meanwhile, the feature-learning methods are better choices; and (2) The 1DCL-based VTC method outperforms the conventional methods with an accuracy of 80.18%, which exceeds the second method (LSTM) by 8.23%

Bis(4-ammonio-4-methyl­pentan-2-one-κO)dioxalato-κ4 O 1,O 2-copper(II)

The title compound, [Cu(C2O4)2(C6H14NO)2], was synthesized by mixing diacetonamine hydrogen oxalate and copper sulfate in ethanol/water. The mol­ecule is centrosymmetric, so two pairs of equivalent ligands lie trans to each other. The CuII center, located on a position with 2/m site symmetry, is six-coordinated by four O atoms from two oxalate ligands at short distances and the carbonyl O atoms from the 4-amino-4-methyl­pentan-2-one ligands at longer distances. Mol­ecules are linked through inter­molecular N—H⋯O hydrogen bonds between the amino groups and carbonyl O atoms; no intra­molecular hydrogen bonds are formed

The impact of ESG performance on firms’ technological innovation: evidence from China

Technological innovation is crucial for creating sustainable corporate value and shaping competitive advantage in the market. ESG, as an indicator of corporate value practices, plays a significant role in enterprise technological innovation. However, there is little empirical evidence to support this claim. This study analyzes the relationship between ESG performance and technological innovation in Chinese A-share listed enterprises from 2011 to 2021. The statistical data shows that strong ESG performance has a significant positive impact on corporate technological innovation. ESG performance can promote corporate technological innovation through external mechanisms, such as enhancing corporate network location and increasing institutional shareholding. Additionally, internal mechanisms, such as reducing labor costs and easing financing constraints, can also promote corporate technological innovation. The impact of ESG performance on corporations exhibits heterogeneity, with ESG performance promoting innovation more strongly among labor-intensive firms, non-state-owned firms, highly competitive industries, and mature firms. Based on the study results, it is recommended that enterprises actively practice ESG development concepts, optimize their equity structure, strengthen information communication with stakeholders, and alleviate problems such as information asymmetry to improve their technological innovation. The government should focus on enterprise characteristics, improve ESG development policies, and promote enterprise innovation through ESG performance

Sea Ice Extraction via Remote Sensed Imagery: Algorithms, Datasets, Applications and Challenges

The deep learning, which is a dominating technique in artificial intelligence, has completely changed the image understanding over the past decade. As a consequence, the sea ice extraction (SIE) problem has reached a new era. We present a comprehensive review of four important aspects of SIE, including algorithms, datasets, applications, and the future trends. Our review focuses on researches published from 2016 to the present, with a specific focus on deep learning-based approaches in the last five years. We divided all relegated algorithms into 3 categories, including classical image segmentation approach, machine learning-based approach and deep learning-based methods. We reviewed the accessible ice datasets including SAR-based datasets, the optical-based datasets and others. The applications are presented in 4 aspects including climate research, navigation, geographic information systems (GIS) production and others. It also provides insightful observations and inspiring future research directions.Comment: 24 pages, 6 figure

The Changing Patterns in Grasslands and Soil Fertility along the Eastern Eurasian Steppe Transect across China–Mongolia–Russia

This paper analyses the adaptation and change in species along the north-south Eastern Eurasian Steppe Transect across China – Mongolia – Russia and considers the implications for climate change and management. The plant community diversity, above-ground biomass, N:P ratios of community and of dominant species, soil N (nitrogen), soil P (phosphorus) and AP (available phosphorus) contents were studied along a 1400 km north-south transect. The main findings were: (1) the community diversity and productivity decreased with the increase in latitude and a significant negative correlation was found between the many plant characteristics and latitude (P \u3c 0.05) – decreasing diversity, biomass and N:P ratios; (2) soil AP content was lowest in Inner Mongolia, whereas no significant change in soil total P with latitude was found in China-Mongolia-Russia transect, a significant positive correlation was detected between the soil nutrient (N and AP) and latitude (P \u3c 0.05); (3) a significant positive correlation was evident between plant community P content and soil AP content (P \u3c 0.01), but a negative correlation was found between community N:P ratio and soil AP content (P \u3c 0.05). The soil AP content can be used as a soil properties indicator to reflect the plant communities P content and N: P ratio. It is suggested that greater human activities in Inner Mongolia may be an important factor affecting soil AP content, community N:P and plant growth

Impact of hypertension and smoking on the rupture of intracranial aneurysms and their joint effect

Background In general population, the prevalence of intracranial aneurysm reaches as high as three percent. The goal of the study was to analyze retrospectively the independent risk factors for the rupture of intracranial aneurysms and their joint effect. Methods The records and angiographies of continuous 519 intracranial aneurysm patients treated at our center between February 2013 and July 2014 were retrospectively analyzed. Ruptured group and unruptured group were included in the study according to their clinical and imaging information. Univariate analysis and multivariate logistic regression analysis was used to identified independent risk factors for the rupture of intracranial aneurysms. We assessed the joint effect of independent risk factors for the rupture of intracranial aneurysms with an additional logistic regression analysis. Results The results of multivariate analysis show that hypertension (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.05–2.18) and smoking (odds ratio [OR], 1.57; 95% confidence interval [CI], 1.06–2.33) were independent risk factors for rupture of intracranial aneurysms. The joint risk of hypertension and smoking was higher (OR, 2.28; 95% CI, 1.29–4.02) than the risks of hypertension (OR, 1.74; 95% CI, 1.11–2.72) and smoking (OR, 1.86; 95% CI, 1.05–3.29) independently. Conclusions Hypertension and smoking increase of the rupture risk of intracranial aneurysms. And the joint risk of hypertension and smoking was higher than the risks of hypertension and smoking independently

Stent-assisted coiling of very small wide-necked intracranial aneurysms: Complications, anatomical results and clinical outcomes

Background and objective Treatment of very small (≤3mm) wide-necked intracranial aneurysms remains controversial, we investigated the efficacy and safety of stent-assisted coiling of such aneurysms. Methods From September 2008 to December 2012, 112 very small wide-necked intracranial aneurysms in 108 patients were embolized with stent-assisted coiling. We assessed the initial neurological conditions, complications and anatomic results. The follow-up results were evaluated with DSA and mRS. Results Stent deployment was successful in 104 of 108 procedures (96.3%). 11 complications (10.2%) occurred during procedures, including 5 events of aneurysm rupture, 3 events of thromboembolism. The rate of complication, rupture and thromboembolism was not statistically different between the ruptured and unruptured patients (P=0.452, P=0.369, P=1.000, respectively). The initial aneurysmal occlusion was Raymond scale (RS) 1 in 34 patients (31.5%), RS2 in 53 patients (49.1%), and RS3 in 21 patients (19.4%). 79 aneurysms were available for anatomic follow-up of 12–47 months, stable occlusion in 45 aneurysms (57.0%), progressive complete occlusion in 34 aneurysms (43.0%). 95 patients(88.0%) were available for a clinical follow-up of 12–52 months, 92 patients (96.8%) had favorable clinical outcomes (mRS ≤2), 3 patients (3.2%) had morbidity (mRS: 3–5). The morbidity was not statistically different between the ruptured and unruptured patients (P=1.000). Conclusions Stent-assisted coiling of very small wide-necked intracranial aneurysms may be effective and safe. Because of low risk of rupture in such aneurysms, the coiling of unruptured such aneurysms must be selective. The long-term efficacy and safety of coiling such aneurysms remains to be determined in larger prospective series