The Insulation Properties of Oil-Impregnated Insulation Paper Reinforced with Nano-TiO 2

Oil-impregnated insulation paper has been widely used in transformers because of its low cost and desirable physical and electrical properties. However, research to improve the insulation properties of oil-impregnated insulation paper is rarely found. In this paper, nano-TiO2 was used to stick to the surface of cellulose which was used to make insulation paper. After oil-impregnated insulation paper reinforced by nano-TiO2 was prepared, the tensile strength, breakdown strength, and dielectric properties of the oil-impregnated insulation paper were investigated to determine whether the modified paper had a better insulation performance. The results show that there were no major changes in tensile strength, and the value of the breakdown strength was greatly improved from 51.13 kV/mm to 61.78 kV/mm. Also, the values of the relative dielectric constant, the dielectric loss, and conductivity declined. The discussion reveals that nano-TiO2 plays a major role in the phenomenon. Because of the existence of nano-TiO2, the contact interface of cellulose and oil was changed, and a large number of shallow traps were produced. These shallow traps changed the insulation properties of oil-impregnated insulation paper. The results show that the proposed solution offers a new method to improve the properties of oil-impregnated insulation paper

JOINT DESIGN AND MOTION RESEARCH OF ENTERTAINMENT ANTHROPOMORPHIC ROBOT

Joint design and motion research is key to the design and research of entertainment Anthropomorphic robot,It direct impact on attitude and balance of robot motion. So,we focus on research Joint structure design and joint movement. Joint of robot hand and foot is designed by human engineering principle and finite element analysis method. Solution of joint position and velocity is obtained base on establishing joint coordinates and calculation. Effective solve robot movement in the process of stability with analysis of the balance of motion. Find a way to achieve robot walking,turning and lateral movement and other humanoid movements by the study the effect of the slip and calculation of the sliding force. A fixed frequency current control method is proposed,and realized robot key gait planning

Financial literacy and risky asset holdings: evidence from China

Although financial literacy is important for participating in financial markets, the level of financial literacy of Chinese consumers is low compared with those in developed countries. Using data from the 2014 China Survey of Consumer Finances, we examine the relation between financial literacy and the risky asset holding behaviour of Chinese households, in the context of an emerging financial market with a distinct institutional background. The findings reveal that consumers with higher levels of financial literacy are more likely to hold risky financial assets than those with lower levels. The potential impacts are derived mainly from advanced financial literacy

Could Ti6Al4V be alternative as a bearing surface articulated with polymer in artificial cervical disc?

In order to study the feasibility for Ti6Al4V (TC4) used as a bearing surface in artificial cervical disc, the wear behaviors of polymer-on-Ti6Al4V pairs were assessed in vitro for 10 million cycles (MC) using a wear simulator. The material of polymer ball included conventional ultra-high molecular weight polyethylene (CPE), cross-linking UHMWPE (XPE) and poly ether ether ketone (PEEK). The artificial cervical disc was simplified and designed as a ball-on-socket model with the material configuration of CPE/TC4, XPE/TC4 and PEEK/TC4, respectively. The wear severity, location and damage type on the articulating surfaces were analyzed by SEM. The results indicated that the CPE and PEEK components revealed severe wear and surface damage with a mix failure mechanism of abrasive wear, ploughed grooves and fatigue cracks. For the polymer balls, the edge zone revealed more severe wear characterized by wear grooves and fatigue cracks as well as squeezing traces than the central zone characterized by linear and arc-shaped sliding scratches. In addition, there was a special damage type characterized by severe arc-shaped wear grooves in the edge zone of the polymer ball. However, TC4 component only indicated scratches after wear testing. The average wear rates were 0.83 ± 0.23 mg/MC, 0.15 ± 0.08 mg/MC and 1.28 ± 0.32 mg/MC for CPE/TC4, XPE/TC4 and PEEK/TC4 pair, respectively. Hence, XPE/TC4 pair was the most wear resistant. Considering the biotribological behavior in totality, TC4 may be alternative as a bearing surface articulated with polymer in artificial cervical disc

Investigation of Whole and Glandular Saliva as a Biomarker for Alzheimer’s Disease Diagnosis

Salivary Aβ40, Aβ42, t-tau, and p-tau 181 are commonly employed in Alzheimer’s disease (AD) investigations. However, the collection method of these biomarkers can affect their levels. To assess the impact of saliva collection methods on biomarkers in this study, 15 healthy people were employed in the morning with six saliva collection methods. The chosen methods were then applied in 30 AD patients and 30 non-AD controls. The levels of salivary biomarkers were calculated by a specific enzyme-linked immunosorbent assay. The receiver operating characteristic was utilized to assess salivary biomarkers in AD patients. The results demonstrated that the highest levels of salivary Aβ40, Aβ42, t-tau, and p-tau were in different saliva collection methods. The correlations between different saliva biomarkers in the same collection method were different. Salivary Aβ40, Aβ42, t-tau, and p-tau had no significant association. Salivary Aβ42 was higher in AD than in non-AD controls. However, p-tau/t-tau and Aβ42/Aβ40 had some relevance. The area under the curve for four biomarkers combined in AD diagnosis was 92.11%. An alternate saliva collection method (e.g., USS in Aβ40, UPS in Aβ42, t-tau, SSS in p-tau 181) was demonstrated in this study. Moreover, combining numerous biomarkers improves AD diagnosis

Novel electro-hydraulic position control system for primary mirror supporting system

In the field of modern large-scale telescope, primary mirror supporting system technology faces the difficulties of theoretically uniform output force request and bias compensation. Therefore, a novel position control system combining hydraulic system with servo motor system is introduced. The novel system ensures uniform output force on supporting points without complicating the mechanical structure. The structures of both primary mirror supporting system and novel position system are described. Then, the mathematical model of novel position control system is derived for controller selection. A proportional–derivative controller is adopted for simulations and experiments of step response and triangle path tracking. The results show that proportional–derivative controller guarantees the system with micrometer-level positioning ability. A modified proportional–derivative controller is utilized to promote system behavior with faster response overshoot. The novel position control system is then applied on primary mirror supporting system. Coupling effect is observed among actuator partitions, and relocation of virtual pivot supporting point is chosen as the decoupling measurement. The position keeping ability of the primary mirror supporting system is verified by rotating the mirror cell at a considerably high rate. The experiment results show that the decoupled system performs better with smaller bias and shorter recovery time

Dynamic navigation : integrating GL-STGCNN and MPC for collision avoidance with future awareness

Existing ship dynamic collision avoidance methods mostly rely on the instantaneous motion information of surrounding ships to make decisions. This makes it difficult to adapt to changes in the motion states of surrounding ships, which may lead to collisions between ships. To improve the safety of dynamic collision avoidance methods, this paper combines the multi-ship trajectory prediction model GL-STGCNN with model predictive control for ship dynamic collision avoidance tasks. Firstly, the interaction between ships is extracted through GL-STGCNN to predict the future trajectories of surrounding ships. Then, the objective function based on the artificial potential field method and the velocity obstacle method is optimized to control the ship to complete the dynamic collision avoidance task. The performance of the dynamic collision avoidance method is verified and analyzed in the ship navigation scenario simulated by AIS data. The experiments show that the new ship dynamic collision avoidance method not only complies with the COLREGs, but also can flexibly select the collision avoidance method according to different scenarios. In addition, the theoretical collision avoidance threshold distance based on the MPC objective function shows a high degree of fit with the actual collision avoidance trigger distance observed in the simulation verification

The power flow algorithm for AC/DC microgrids based on improved unified iteration method

In response to the complexity of the Jacobian matrix inversion process in the power flow algorithm for AC/DC microgrids, leading to large memory requirements and susceptibility to convergence issues, a novel power flow algorithm based on an improved unified iteration method for AC/DC microgrids is proposed. Firstly, the fundamental equations of the unified iteration method and the characteristics of DC systems are analyzed. The reactive power correction terms and voltage phase correction differences are removed from the modified equations of the unified iteration method, and result in a reduction in the order of the Jacobian matrix in the power flow algorithm. Subsequently, the improved IEEE 11-node system is subjected to simulation verification to attain precise power flow solutions for hybrid AC/DC microgrids. The theoretical analysis identifies the main influencing parameters of active and reactive power errors and assesses their impact factors. Finally, experimental validation of the improved power flow algorithm is carried out on a physical platform, clarifying the applicability range of the proposed method. The research results indicate that within allowable error margins, the proposed approach reduces the difficulty of Jacobian matrix inversion, resulting in an 80% increase in computational speed compared to the unified iteration method. It is suitable for microgrid systems with short electrical distances and small magnitudes of node voltage amplitudes and phase differences