Search

With the rapid development of wind energy, the subsynchronous oscillations (SSO) involved with wind conversion systems, has been the focus of academic concern. To analyse the subsynchronous control interaction (SSCI) issue of multi-converters (wind-power converter and widespread SVGs), the state matrix of a typical PMSGs-based offshore wind farm system including SVGs is constructed . It is proposed that SVGs in wind farm may cause SSCI issue by their uncoordinated control targets. Under certain conditions, the SSCI between SVGs forms the dominant oscillation mode, delivered with variation of the SSO frequency. By calculating the influence factors along with different converters, it can be concluded that unreasonable parameter configuration of converters and variations of operating conditions affect the SSCI characteristics. At last, time domain simulation is used to verify the SSCI mechanism and characteristics of the PMSG-based offshore wind farm and SVGs.

Owing to the challenges faced by two-lane entrance ramps in merging areas on expressways in handling the growing traffic volume, designers are considering implementing three-lane entrance ramps. This approach alleviates capacity bottlenecks and facilitates efficient, safe, and green operations. However, according to the traditional design strategy, the long auxiliary lanes will bring large land occupation and construction consumption, creating obstacles to the reconstruction. To address this issue, this study proposes two new strategies and discusses the applicability of each scheme. A VISSIM microsimulation model was developed and calibrated using the collected data, and five evaluation indicators assessing environmental protection, capacity, traffic efficiency, safety, and construction consumption were selected. This study also presents a comprehensive evaluation(CE) method that combines the CRITIC (Criteria Importance Through Intercriteria Correlation) method and TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution), which considers the association between indicators and offers a more rational evaluation, aiming to recommend optimal designs for various traffic cases. The results indicate that two-lane ramps are still the preferred choice for lower traffic volumes and merging ratios, whereas three-lane ramps demonstrate excellent potential for application under heavy traffic conditions. The CE reveals substantial improvements in optimal designs, with capacity, delay, CO emissions, and conflicts showing maximum enhancements of approximately 20%, 45%, 5%, and 55%, respectively.

Artificial intelligence approaches inspired by human cognitive function have usually single learned ability. The authors propose a multimodal foundation model that demonstrates the cross-domain learning and adaptation for broad range of downstream cognitive tasks.

As the offshore wind installations are moving further from shore, the transmission distance also increases. Synthesize the cost of construction and maintenance, as well as the technical maturity, grid-connection via AC network will still be a preferred power delivery method for offshore wind power projects in the near future. However, according to the “8•9” blackout in the UK, there is sub-synchronous oscillation (SSO) risk in the AC network connected offshore wind projects, which was attributed to the mismatch between the power electronic source and the power grid. In this article, both eigenvalue analysis and time-domain simulation method are used to evaluate the operating SSO stability of grid integration of large scale offshore wind power. It suggests that transmission system via long distance cables naturally forms a weak AC network, and the SSO characteristics of AC grid connected offshore wind farm is closely related to the wind turbine parameters, offshore distance and the active power output level. At last, the principle of parameter configuration in offshore wind turbines is proposed based on different offshore distances.

Flexible AC transmission systems have shown effective functionalities in promoting the system operation security and service reliability. Facing with series-compensated lines, subsynchronous resonance (SSR) may jeopardise the stability and mechanical facilities. The control strategy and simulation model of a unified power flow controller (UPFC) based on the dq decoupling control are deduced and constructed. Considering the impacts of grid-connected wind farms, SSR characteristics of the series-compensated system with UPFC are studied by the complex torque coefficient method and time-domain simulation. The results verify the capability of UPFC in attenuating SSR in wind farm integrations by utilising subsynchronous damping controllers coordinated with UPFC's main controllers. It also suggests that the shunt transformer−converter has a slight effect on SSR, whereas the series transformer−converter affects the system resonance characteristics significantly. Simulations are carried out on a typical power system model integrated with wind turbines.

Cellular immunotherapy has become a potential therapeutic method for different diseases. Herein, we reported clinical trial results of Cytokine-induced killer (CIK) cells used for patients with hepatitis B, cirrhosis and liver cancers from 2000 to 2015. Results showed CIK cell therapeutic effects were closely positively associated with CIK cell numbers, treated times and HBV genotypes. Different stages of HBV patients treated with > 1010 CIK cells per time for more than ten times exhibited remarkable decrease of HBV DNA numbers (P < 0.01), ALT and AST gradually recovered to normal scope, cytokine factors such as IFN-γ, IL-1b, IL-2, IL-4, IL-6, IL-10, IL-22 and IL-27 exhibited obvious increase, lifespan of patients with cirrhosis and hepatocellular carcinoma were extended, and that all the patients felt better in sleep, diet and pain during the period of CIK therapy. In conclusion, CIK cell therapy is a good alternative therapeutic method and can be effectively used for treatment of different stages of HBV patients.