40 research outputs found
Idiopathic Ventricular Arrhythmias Originating From the Pulmonary Sinus Cusp Prevalence, Electrocardiographic/Electrophysiological Characteristics, and Catheter Ablation
AbstractBackgroundIdiopathic ventricular arrhythmias (VAs) originating from the pulmonary sinus cusp (PSC) have not been sufficiently clarified.ObjectivesThe goal of this study was to investigate the prevalence, electrocardiographic characteristics, mapping, and ablation of idiopathic VAs arising from the PSC.MethodsData were analyzed from 218 patients undergoing successful endocardial ablation of idiopathic VAs with a left bundle branch block morphology and inferior axis deviation.ResultsTwenty-four patients had VAs originating from the PSC. In the first 7 patients, initial ablation performed in the right ventricular outflow tract failed to abolish the clinical VAs but produced a small change in the QRS morphology in 3 patients. In all 24 patients, the earliest activation was eventually identified in the PSC, at which a sharp potential was observed preceding the QRS complex onset by 28.2 ± 2.9 ms. The successful ablation site was in the right cusp (RC) in 10 patients (42%), the left cusp (LC) in 8 (33%), and the anterior cusp (AC) in 6 (25%). Electrocardiographic analysis showed that RC-VAs had significantly larger R-wave amplitude in lead I and a smaller aVL/aVR ratio of Q-wave amplitude compared with AC-VAs and LC-VAs, respectively. The R-wave amplitude in inferior leads was smaller in VAs localized in the RC than in the LC but did not differ between VAs from the AC and LC.ConclusionsVAs arising from the PSC are not uncommon, and RC-VAs have unique electrocardiographic characteristics. These VAs can be successfully ablated within the PSC
A generic classifier-ensemble approach for biomedical named entity recognition
In named entity recognition (NER) for biomedical literature, approaches based on combined classifiers have demonstrated great performance improvement compared to a single (best) classifier. This is mainly owed to sufficient level of diversity exhibited among classifiers, which is a selective property of classifier set. Given a large number of classifiers, how to select different classifiers to put into a classifier-ensemble is a crucial issue of multiple classifier-ensemble design. With this observation in mind, we proposed a generic genetic classifier-ensemble method for the classifier selection in biomedical NER. Various diversity measures and majority voting are considered, and disjoint feature subsets are selected to construct individual classifiers. A basic type of individual classifier – Support Vector Machine (SVM) classifier is adopted as SVM-classifier committee. A multi-objective Genetic algorithm (GA) is employed as the classifier selector to facilitate the ensemble classifier to improve the overall sample classification accuracy. The proposed approach is tested on the benchmark dataset – GENIA version 3.02 corpus, and compared with both individual best SVM classifier and SVM-classifier ensemble algorithm as well as other machine learning methods such as CRF, HMM and MEMM. The results show that the proposed approach outperforms other classification algorithms and can be a useful method for the biomedical NER problem.<br /
Research on Steering Stability Control Strategy of Four-wheel Independent Electric Drive Special Vehicles
In order to solve the steering stability problem of a special four-wheel independent electric vehicle, a dynamic model of the vehicle was established to analyze the cause of vehicle instability. A steering stability controller was designed, which included the upper yaw moment controller and the lower driving force distribution controller. Based on the sliding mode control algorithm, the yaw moment controller determines the yaw moment required while the vehicle is moving by controlling the yaw rate and sideslip angle. Based on the safety distribution method, the driving force distribution controller selects the sum of tire utilization rate as the optimization function to realize the optimal distribution of yaw moment. Software of MATLAB/Simulink and CarSim were used to build a co-simulation platform, and the designed steering stability controller was analyzed and verified. The simulation results show that the steering stability controller is helpful to improve the steering ability and handling stability of the vehicle in the extreme working conditions
Do <i>Miscanthus</i><i> lutarioriparius</i>-Based Oriented Strand Boards Provide Environmentally Benign Alternatives? An LCA Case Study of Lake Dongting District in China
Miscanthus lutarioriparius(M. lutarioriparius) in Lake Dongting District are in the situation of being discarded due to the government’s environmental policy, the decomposition of which will bring another pollution risk. The purpose of this study is to environmentally analyze the production of M. lutarioriparius-based oriented strand particleboards(M.OSB) as alternatives to the conventional artificial boards. The production systems were evaluated from a cradle-to-gate perspective using the Life Cycle Assessment(LCA)methodology. Our results showed that the M.OSB had an overall better profile than wood panels, identifying the production of starch adhesives and bio-fuels as the main environmental hotspots. It was also found that annual harvesting and utilization of M. lutarioripariuscould ease the burden to the environment during the decomposition of this plant, and further improve the environmental performance of M.OSB. Sensitivity analyses were conducted on the key parameters, suggesting that there are opportunities for improvement. This study provides useful information for enterprises and policymakers on where to focus their activities, with the aim of making the future of M. lutarioriparius utilization more technically and environmentally favourable
Design of lateral dynamic control objectives for multi-wheeled distributed drive electric vehicles
The lateral dynamic control system for electric vehicles aims to improve vehicle performance, making it critical to propose reasonable lateral dynamic control objectives. Therefore, in this study, a novel lateral dynamic control objectives is proposed for multi-wheeled distributed drive electric vehicles. Initially, utilizing the classical two-degrees-of-freedom (2DOF) vehicle model, two initial yaw rate references were established for handling characteristics of manoeuvrability and stability, respectively. The yaw rate references consider the vehicle velocity, steering wheel angle and road friction coefficient limitations. Considering the vital role of the sideslip angle in ensuring vehicle stability, a sophisticated weighting factor was developed based on a detailed analysis of the vehicle dynamics within the sideslip angle-sideslip angle rate phase plane. The weighting factor was determined based on the position of the vehicle state in the phase plane. This factor was adeptly applied to harmonise our dual control objectives, culminating in an integrated control aim that encapsulates the individual benefits of each. Finally, the lateral dynamic control objective was realised using a direct yaw moment control (DYC) system. The effectiveness of the proposed control objective was validated through hardware-in-the-loop (HIL) simulations
Research on Speed Sensorless Vector Control System of Asynchronous Motor Based on MRAS
This paper analysed the basic principle of speed sensorless vector control system. Based on speed and current closed loop vector control, combined with a simple and feasible current hysteresis control strategy, the whole speed sensorless system of asynchronous motor is simulated in MATLAB/Simulink. The method uses the Model Reference Adaptive System (MRAS). The observation and analysis of waveform shows that the system has good static performance and robustness. The control effects are also as similar as the vector control system which contains speed sensor
Analyzing Macro-Level Ecological Change and Micro-Level Farmer Behavior in Manas River Basin, China
Environmental degradation is closely related to unreasonable land use behaviors by farmers. In this study, participatory rural assessment (PRA) is used to conduct a detailed survey of farmers and plots and to collect relevant natural and social statistics. The accuracy of remote sensing data is verified by comparative analysis, and the change in status of various land use types in each research period is reflected by the change in the dynamic degree and change in range. We examine how farmers’ attitudes and behaviors affect environmental degradation, using a sample of 403 farmers in China’s Manas River Basin. Due to age, education, income and other differences, farmers’ land use behaviors, as well as their attitude toward and feelings about environmental degradation, vary greatly. We found that most farmers considered the environment to be very important to their lives and crop production, but nearly 21% did not know the causes of environmental degradation and nearly 8% did not consider the environmental impacts of their crop production activities. A new model for oasis expansion—land integration—is presented here. This model can increase the area of cultivated land, reduce cultivated land fragmentation, save irrigation water, improve the field microclimate and form a good ecological cycle. Through land transfer, ecological compensation and ecological protection incentives, the government should guide farmers’ land use behaviors toward cooperation with the river basin’s ecological protection and land use planning
Analysis of Ecological and Economic Benefits of Rural Land Integration in the Manas River Basin Oasis
Land consolidation is an effective means of promoting the regularization of fragmented arable land, optimizing the allocation of land resources and improving the environment in farming areas, as well as an important means of increasing the economic returns of farming households, and it is important to scientifically assess the ecological and economic benefits of agricultural land consolidation. In this study, participatory rural assessment (PRA) was used to investigate, in detail, the meaning, satisfaction and changes in farmland rehabilitation before and after implementation. The accuracy of the remote sensing data was verified through an experiment on the net cultivation coefficient. We used a sample of 447 farmers from nine villages in Manas County to study the differences in plot area, crop unit value, income and irrigation before and after the farmers’ integration. We found that, after the integration of farmland, the cultivated area increased significantly, the crop unit yield increased by at least 42.66%, the average income of farmers increased by a value of RMB 4324/ha and the water savings were all higher than 7.18 m3/ha. At the same time, after the integration of farmland, the number of plots was significantly reduced, the arable land became more regular and the microclimate of the farmland improved significantly. The government and individuals should follow the concept and construction requirements of the “community of life in mountain, water, forest, lake, grass and sand”, consider the economic and ecological benefits of land consolidation, ensure the quality of farmland ecosystems, actively explore new models of land consolidation and stimulate the economic vitality of rural areas
Microstructure, mechanical properties and corrosion resistance properties of Ni-Co- Mn-Sn-Gd magnetic shape memory alloys
Ni-Mn-Sn alloy is considered to be one of the most potential refrigerant, sensor and driver materials, but its practical application is hindered to a large extent due to the inherent brittleness of intermetallic compounds.The microstructure, martensitic transformation, mechanical properties and seawater corrosion resistance of Ni45Co5Mn38Sn12-xGdx(x=0.3, 0.6, 1, 1.5, atom fraction/%, the same below) magnetic shape memory alloy were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electron universal capacity testing machine and electrochemical workstation.The experimental results show that when the content of Gd is 0.3%, a mottled precipitate phase appears, and a particle precipitate phase is found around the mottled precipitate phase. The two precipitates increase gradually and are connected together in a network distribution. The doping of Gd increases the concentration of valence electrons in the alloy matrix, which leads to the increase of the alloy martensitic transformation temperature. When Gd content is 1.5%, the compressive strength of the alloy can reach 1258 MPa and the compressive fracture strain can reach 13.7%. In addition, the corrosion resistance of Ni-Co-Mn-Sn-Gd alloy is better than that of 304 stainless steel, and the corrosion resistance of the alloy gradually increases with the increase of Gd content